Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02651403 2009-01-28
ANTI-ROLLAWAY DEVICE FOR TRUCKS AND EQUIPMENT WITI-I FLUID AND
ELECTRICALLY ACTUATED 13RAKE(S)
BACKGROUND OF TI IF INVI?NTION
[0001] Field of the Invention
[0002] The present invention relates to preventing inadvertent rollaway of
vehicles having
fluid, e.g., air or hydraulic, or electrically controlled parking brake(s).
[0003] Description of Related Art
[0004] Fluid actuated parking brake(s), such as air pressure controlled
parking brake(s) and
hydraulic parking brake(s), or electric parking brake(s) are well-known in the
art. Vehicles
including such brake(s) typically include a parking control valve or servo
controlled brake(s)
operating under the control of an actuation means, such as a lever, knob or
switch, or a switch,
respectively, typically disposed inside the operator compartment of the
vehicle for controlling
the supply of pressurized fluid, e.g., air or hydraulic fluid, or electrical
energy to the brake(s)
whereupon the brake(s) can be set to the fully "on" state in a manner known in
the art.
[0005] It is not uncommon for operators of such vehicles to exit the vehicles
without setting
the parking brake. In many instances, failure to set the parking brake has
resulted in the vehicle
inadvertently moving without an operator being present, a so-called "rollaway"
condition. In
many instances of rollaway, it is not uncommon for such vehicles to collide
with other vehicles,
structures or individuals causing damage to property and equipment, with
resulting workmen's
compensation claims and/or personal injury claims involving serious injury
and/or death.
[0006] It would, therefore, be desirable to provide an anti-rollaway device
that avoids
inadvertent rollaway of vehicles having fluid or electric controlled parking
brake(s).
SUMMARY OFTIII INVINI'ION
[0007] An embodiment of a vehicle anti-rollaway device includes a source of
electrical
power; means responsive to the provision and withholding of electrical power
from the source of
electrical power for controlling the operation of a parking brake of the
vehicle as a function
thereof; and means responsive to the presence and absence of a vehicle
operator at a
predetermined location in the vehicle for controlling said provision and
withholding of electrical
power from the means for controlling.
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[0008] The device can further include means responsive to a change in
pressurized fluid
supplied to a service brake of the vehicle for controlling the operation of
the means for
controlling the operation of the parking brake.
[0009] The device can further include means responsive to the activation of
the parking
brake by the means for controlling the operation of a parking brake for
recording one or more of
the following: a time of activation of the parking brake, a date of activation
of the parking brake,
or a geographic location of the vehicle when activation of the parking brake
occurred.
[0010] The means for controlling the operation of the parking brake can
include a parking
control valve operatively coupled between a source of pressurized fluid and
the parking brake in
the form of a fluid controlled parking brake, said parking control valve
operative for providing
and withholding pressurized fluid from the parking brake in response to a
state of an actuation
means.
[0011] The parking control valve can be either mechanically or electrically
actuated. The
actuation means can include either: (1) a knob or lever operative for
mechanically controlling a
state of the parking control valve, in the form of a mechanically actuated
parking control valve,
to provide or withhold pressurized fluid from the parking brake of the
vehicle; or (2) a parking
control switch operatively coupled to the parking control valve, in the form
of an electrically
actuated parking control valve, for controlling the state of the parking
control valve to provide or
withhold pressurized fluid from the parking brake of the vehicle.
[0012] The means for controlling the operation of the parking brake further
can include a
solenoid valve operatively coupled to receive pressurized fluid from the
source of pressurized
fluid, said solenoid valve responsive to the provision and withholding of
electrical power from
the source of electrical power for controlling the provision of pressurized
fluid to the parking
brake.
[0013] The operation of the solenoid valve can be independent of the slate of
the actuation
means.
[0014] The means for controlling the operation of the parking brake can
further include a
switch responsive to the parking control valve providing and withholding
pressurized fluid to
and from the parking brake for controlling the response of the solenoid valve
to the provision of
electrical power from the source of electrical power.
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[0015] The means responsive to the presence and absence of a vehicle operator
can include a
switch responsive to the presence and absence of the vehicle operator on a
seat of the vehicle.
The means responsive to the presence and absence of a vehicle operator can
further include a
switch responsive to the presence and absence of at least one foot of the
vehicle operator at a
predetermined location in the vehicle.
[0016] The device can further include a speed sensor operative for outputting
a signal
indicative of the speed of the vehicle; and a speed control operatively
coupled between the
source of electrical power and the means for controlling the operation of a
parking brake of the
vehicle, said speed control responsive to the signal output by the speed
sensor for providing and
withholding electrical power to and from the means for controlling the
operation of the parking
brake of the vehicle.
[0017] The speed control can withhold electrical power from the means for
controlling the
operation of a parking brake of the vehicle when the signal output by the
speed sensor indicates
the vehicle is at or below a predetermined speed.
[0018] Another embodiment of a vehicle anti-rollaway device includes a parking
control
valve operative for controlling the supply of pressurized fluid to a parking
brake of the vehicle; a
speed sensor operative for outputting a speed signal corresponding to a speed
of the vehicle; a
speed control responsive to the speed signal for outputting a signal as a
function of the speed
sensor indicating the vehicle is at or below a predetermined speed; a solenoid
valve responsive to
the signal output by the speed control for controlling the supply of
pressurized fluid to the
parking control valve; a first switch operative for controlling the response
of the solenoid valve
to the signal output by the speed control as a function of the supply of
pressurized fluid to the
parking brake of the vehicle; and a second switch operative for controlling
the response of the
solenoid valve to the signal output by the speed control as a function of the
presence of an
operator at a predetermined location in the vehicle.
[0019] When (1) the speed control is outputting the signal, (2) the first
switch is in a first
state in response to the passage of pressurized fluid to the parking brake of
the vehicle via the
parking control valve and the solenoid valve, and (3) the second switch is in
a first state in
response to the presence of an operator at the predetermined location in the
vehicle, in response
to the operator leaving the predetermined location in the vehicle, the second
switch changes state
CA 02651403 2009-01-28
whereupon the solenoid valve becomes responsive to the signal output by the
speed control for
terminating the supply of pressurized fluid to the parking brake of the
vehicle.
[0020] The device can include a third switch operative for controlling the
response of the
solenoid valve to the signal output by the speed control as a function of a
change in a fluid
pressure supplied to a service brake of the vehicle.
[0021] When (1) the speed control is outputting the signal, (2) the first
switch is in a first
state in response to the passage of pressurized fluid to the parking brake of
the vehicle via the
parking control valve and the solenoid valve, and (3) the second switch is in
a first state in
response to the operator being absent from the predetermined location in the
vehicle, in response
to a predetermined change in the fluid pressure supplied to the service brake
of the vehicle, the
third switch can change state whereupon the solenoid valve becomes responsive
to the signal
output by the speed control for terminating the supply of pressurized fluid to
the parking brake of
the vehicle.
[0022] Another embodiment of a vehicle anti-rollaway device for use on a
vehicle equipped
with a parking control valve operative for controlling the supply of
pressurized fluid to a parking
brake of the vehicle includes a speed control operative for outputting a
signal when the speed of
the vehicle is at or below a predetermined speed; a solenoid valve responsive
to the signal output
by the speed control for controlling the supply of pressurized fluid to the
parking brake of the
vehicle; and a first switch operative for controlling the response of the
solenoid valve to the
signal output by the speed control as a function of the presence and absence
of an operator at a
predetermined location in the vehicle, wherein, in response to the operator
moving from the
predetermined location in the vehicle when pressurized fluid is being supplied
to the parking
brake of the vehicle via the solenoid valve and the parking control valve, the
first switch changes
state whereupon the solenoid valve terminates the supply of pressurized fluid
to the parking
brake of the vehicle.
[0023] The device can further include a second switch for controlling the
response of the
solenoid valve to the signal output by the speed control as a function of a
supply of pressurized
fluid to a service brake of the vehicle, wherein in response to the supply and
absence of the
pressurized fluid to the service brake of the vehicle, the second switch
causes the solenoid valve
to be respectively not responsive and responsive, or vice versa, to the signal
output by the speed
control.
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[0024] The device can further include a second, fluid-pressure controlled
switch operative
for controlling the response of the solenoid valve to the signal output by the
speed control as a
function of the supply of pressurized fluid to the parking brake of the
vehicle, wherein in
response to the supply and absence of pressurized fluid being supplied to the
parking brake of the
vehicle, the second switch causes the solenoid valve to he responsive and not
responsive, or vice
versa, to the signal output by the speed control.
[0025] The first switch, the second switch and a control input of the solenoid
valve can be
connected in series with the signal output by the speed control. The solenoid
valve can be
responsive to the signal output by the speed control received at the control
input of the solenoid
valve for controlling the flow of pressurized fluid to the parking brake of
the vehicle.
[0026] Another embodiment of a vehicle anti-rollaway device includes a valve
operatively
coupled between a source of pressurized fluid and a fluid actuated parking
brake of the vehicle;
and a first switch responsive to the presence and absence of' an operator at a
predetermined
location in the vehicle for controlling the state of the valve to supply or
withhold pressurized
fluid to the parking brake of the vehicle.
[0027] The device can further include a second switch responsive to the supply
of
pressurized fluid to a service brake of the vehicle for controlling the
response of the valve to the
state of the first switch.
[0028] The device can further include a speed control responsive to a speed of
the vehicle for
controlling the response of the valve to the state of the first switch.
[0029] The device can further include a second switch responsive to the supply
of
pressurized fluid to the parking brake for controlling the response of the
valve to the state of the
first switch.
[0030] Another embodiment of a vehicle anti-rollaway device includes a first
switch
responsive to the presence and absence of an operator at a predetermined
location in the vehicle
for controlling the on/off state of a parking brake of the vehicle.
[0031] The device can further include a second switch responsive to the supply
of
pressurized fluid to a service brake of the vehicle for controlling the
response of the parking
brake to the state of the first switch.
[0032] The parking brake can be either a servo controlled parking brake or a
fluid controlled
parking brake.
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[0033] The device can further include a speed control operative for
controlling the on/off
state of the parking brake as a function of the speed of the vehicle.
[0034] The device can further include a second switch operative for
controlling the response
of the parking brake to the state of the first switch.
BRIEF DESCRIPTION OF TILE DRAWINGS
[0035] Figs. 1-4 are schematic drawings showing different embodiments of the
vehicle anti
rollaway devices described herein.
DETAILED DESCRIPTION OF TI It' INVENTION
[0036] Embodiments of the invention will now be described with reference to
the
accompanying figures where like reference numbers correspond to like elements.
[0037] With reference to Fig. 1, one embodiment of an anti-rollaway device
includes a speed
control 4 having a power input coupled to the positive terminal of a battery 2
and a speed sensor
input coupled to the output of a speed sensor 6.
[0038] Speed control 4 can be any suitable and/or desirable speed control. One
exemplary,
non-limiting example of a suitable speed control 4 is available from Hewitt
Industries of 5492
Bulsa Avenue, Huntington Beach, California 92649, part number 030-310 or 030-
317.
However, the use of this particular speed control is not to be construed as
limiting the invention
since it is envisioned that any other suitable and/or desirable speed control
that can perform the
functions of speed control 4 described hereinafter can be utilized.
[0039] Speed sensor 6 can be any suitable and/or desirable speed sensor, such
as a vehicle
speedometer or a magnetic sensor configured to detect rotation of a flywheel,
drive shaft or tire
(not shown) of the vehicle. However, this is not to be construed as limiting
the invention since it
is envisioned that any suitable and/or desirable speed sensor that is capable
of outputting a signal
indicative of movement of the vehicle is envisioned.
[0040] A solenoid valve 8 has a solenoid coil 20 operatively positioned
adjacent an air valve
22 of solenoid valve 8. In operation, in response to solenoid coil 20 not
being energized with
electrical power supplied by battery 2 via speed control 4, air valve 22
permits the passage of
pressurized air from an air pressure source 10 of the vehicle to a parking
control valve 12 of the
vehicle. Conversely, in response to solenoid coil 20 being energized with
electrical power, air
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valve 22 blocks the passage of pressurized air from air pressure source 10 to
parking control
valve 12.
[0041] Parking control valve 12 is of the conventional type that is operative
for supplying or
terminating the supply of pressurized air to one or more parking brake(s) of'
the vehicle in
response to actuation or de-actuation of a suitable actuation means 13
typically disposed within a
driver's compartment of the vehicle. For example, by way of actuation means
13, such as a
knob, lever or switch, parking control valve 12 can be set to withhold
pressurized air from the
vehicle parking brake(s), whereupon said parking brake(s) will be set to their
fully "on" or
engaged state in a manner known in the art.
[0042] The output of parking control valve 12 utilized to supply pressurized
air to the vehicle
parking brake(s) is also coupled to an air pressure controlled switch 14 that
is electrically
connected between solenoid coil 20 of solenoid valve 8 and a seat pressure
switch 16.
[0043] Air pressure controlled switch 14 is operative for electrically
connecting solenoid coil
20 to seat pressure switch 16 in response to the output of pressurized air
from parking control
valve 12. In response to the absence of pressurized air output by parking
control valve 12, air
pressure controlled switch 14 will be in its open state whereupon no
electrical connection exists
between solenoid coil 20 and seat pressure switch 16. In operation, air
pressure controlled
switch 14 prevents solenoid coil 20 from drawing electrical power when the
vehicle parking
brake(s) are set to their "on" position in response to the actuation of
parking control valve 12 to
block the passage of pressurized air to the vehicle parking brake(s).
Conversely, if pressurized
air is output by parking control valve 12 to the vehicle parking brake(s), air
pressure controlled
switch 14 will be in its closed state whereupon when seat pressure switch 16
is in its closed state,
solenoid coil 20 will be energized.
[0044] Seat pressure switch 16 is disposed such that when an operator of the
vehicle sits in
the driver's seat of the vehicle, seat pressure switch 16 will be in its open
state. In contrast, when
the operator is not sitting in the driver's seat, seat pressure switch 16 will
he in its closed state.
[0045] The operation of the embodiment of the anti-rollaway device of Fig. 1,
without the
optional pressure sensing mat system 17 shown in Fig. 1 and described
hereinafter, will now be
described.
[0046] In operation of the vehicle with the operator sitting on the driver's
seat and the
parking control valve 12 set to pass pressurized air to air pressure
controlled switch 14 and the
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vehicle parking brake(s), seat pressure switch 16 will be in its open state
and air pressure
controlled switch 14 will be in its closed state.
[0047] In the event the operator leaves the driver's seat when parking control
valve 12 is
passing pressurized air to air pressure controlled switch 14 and to the
vehicle parking brake(s),
seat pressure switch 16 will move to its closed state whereupon electrical
power is provided by
battery 2 to solenoid coil 20 via speed control 4, air pressure controlled
switch 14, and seat
pressure switch 16. In response to energizing solenoid coil 20 with electrical
power, air valve 22
terminates the supply of pressurized air from air pressure source 10 to
parking control valve 12
whereupon the supply of pressurized air to air pressure controlled switch 14
and to the vehicle
parking brake(s) is terminated. In response to termination of pressurized air
thereto, the vehicle
parking brake(s) are set to their fully "on" state.
[0048] Thus, if the vehicle parking brake(s) are not set to their fully "on"
state by operation
of the parking control valve, and the weight of the vehicle operator is not on
the driver's seat, the
vehicle parking brake(s) will be set to their fully "on" state as a result of
the energization of
solenoid coil 20 and the resultant termination of pressurized air to parking
control valve 12 by air
valve 22. If desired, solenoid valve 8 can be a time delay solenoid valve
whereupon the
operation of air valve 22 to terminate the supply of pressurized air to
parking control valve 12 is
delayed for a predetermined or user settable period after solenoid coil 20 is
energized. This
delay helps avoid the inadvertent actuation of the vehicle parking brake(s).
Speed control 4 also
avoids the accidental activation of the vehicle parking brake(s) during normal
vehicle operation
in a manner to be described hereinafter.
[0049] If the vehicle parking brake(s) are set to their fully "on" state by
way of parking
control valve 12 terminating the supply of pressurized air to the vehicle
parking brake(s) and to
air pressure controlled switch 14, air pressure controlled switch 14 will be
in its open state,
thereby preventing solenoid coil 20 from being energized and unnecessarily
draining battery
power when the vehicle parking brake(s) are already set to their fully "on"
state.
[0050] Parking control valve 12 includes a mechanical interlock that prevents
it from passing
pressurized air to air pressure controlled switch 14 and the vehicle parking
brake(s) after the
supply of pressurized air to parking control valve 12 has been terminated
unless activation means
13 is manipulated by the operator in a suitable manner. Thus, when the supply
of pressurized air
to parking control valve 12 is terminated in response to energizing solenoid
coil 20, whereupon
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pressurized air to air pressure controlled switch 14 is terminated and air
pressure controlled
switch 14 opens, the mechanical interlock of parking control valve 12 prevents
the subsequent
passage of pressurized air to air pressure controlled switch 14 when solenoid
valve 20
deenergizes (in response to air pressure controlled switch 14 opening). This
mechanical
interlock avoids the uncontrolled on/off operation of the vehicle parking
brake(s) that would
otherwise be caused by the open/closed operation of air pressure controlled
switch 14 in response
to energization/de-energization of solenoid valve 20 when seat pressure switch
is in its closed
state.
[00511 To avoid the inadvertent supply of electrical power to solenoid coil 20
when the
vehicle is in use above a predetermined speed, speed control 4 is operative
for sensing the output
of speed sensor 6 which outputs a suitable signal indicative of the vehicle in
motion. When the
vehicle is in motion above a predetermined speed and speed sensor 6 is
outputting a signal
indicative thereof to speed control 4, speed control 4 is operative for
terminating or withholding
the supply of electrical power to solenoid coil 20 from battery 2 in order to
avoid inadvertent
operation of solenoid valve 22 and, hence, the vehicle parking brake(s).
Desirably, in response
to the vehicle coming to a stop, speed sensor 6 outputs a corresponding signal
to speed control 4
which is operative in response thereto for coupling solenoid coil 20 to
battery 2 whereupon the
supply of electrical power to solenoid coil 20 is controlled by air pressure
controlled switch 14
and/or seat pressure control switch 16 in the manner described above.
[0052] In the foregoing description, parking control valve 12 was considered
to be a
mechanically actuated parking control valve 12. However, this is not to be
construed as limiting
the invention.
[00531 Optionally, a pressure sensing mat system 17 can be provided that
includes a pressure
sensing mat 19 disposed on the floor of the vehicle. Pressure sensing mat
system 17 is operative
such that when an operator sits in the drivers seat of the vehicle with one or
both of the
operator's feet on pressure sensing mat 19, the output of pressure sensing mat
system 17 will be
in its open state. When one or both feet of the operator are not on pressure
sensing mat 19,
pressure sensing mat system 17 will be in its closed state.
[00541 Pressure sensing mat system 17 can include any suitable and/or
desirable pressure
sensing mat 19, such as, without limitation, a Tapeswitch < Sensing Mat
distributed by
Tapeswitch Ltd., Unit 38, Drumhead Road, Chorley North Industrial Park,
Chorley, Lancashire,
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United Kingdom. As the switching logic of a conventional pressure sensing mat
is opposite to
the logic needed for pressure sensing mat system 17, it is envisioned that the
logical output of
pressure sensing mat 19 will be inverted by a suitable inverting means, e.g.,
by a second, external
switch or a suitable logic inverting circuit connected to the switching
function of pressure
sensing mat 19 in a suitable manner. Thus, in normal operation of pressure
sensing mat 19
without the suitable inverting means, the output (or switching function) of
pressure sensing mat
19 will be in its closed state when one or both feet of the operator are
disposed on pressure
sensing mat 19 and will be in its open state when the feet of the driver are
not disposed on
pressure sensing mat 19. In contrast, with the use of the suitable inverting
means, pressure
sensing mat system 17 will invert this logic so that the output (or switching
function) of pressure
sensing mat system 17 will be in its open state when one or both feet of the
operator are disposed
on pressure sensing mat 19 and will be in a closed state when the feet of the
driver are not
disposed on pressure sensing mat 19.
[0055] For the purpose of simplicity and illustration, the function of
pressure sensing mat
system 17 is shown in Fig. 1 as a switch. However, it is to be appreciated
that pressure sensing
mat system 17 includes not only pressure sensing mat 19 but also includes the
suitable inverting
means for inverting the logic function of a pressure sensing mat 19.
Nevertheless, it is
envisioned that if a pressure sensing mat were available that could provide
the proper logic
switching function, namely, an open state when one or both feet of the
operator are on such
pressure sensing mat and a closed state when one or both feet of the operator
are not on such
pressure sensing mat, then such pressure sensing mat would comprise the
entirety of pressure
sensing mat system 17.
[0056] As shown in Fig. 1, the switching function of pressure sensing mat
system 17 is in
series with the switching functions of air pressure controlled switch 14 and
seat pressure switch
16. The operation of the embodiment of the anti-rollaway device of Fig. 1 with
the optional
pressure sensing mat system 17 being utilized in combination with seat
pressure switch 16 will
now be described.
[0057] In operation of the vehicle with the operator sitting on the drivers
seat with one or
both of the operator's feet on pressure sensing mat 19 of pressure sensing mat
system 17 and
with the parking control valve 12 set to pass pressurized air to air pressure
controlled switch 14
and the vehicle parking brake(s), seat pressure switch 16 will be in its open
state, the switching
CA 02651403 2009-01-28
function provided by pressure sensing mat system 17 will be in its open state,
and air pressure
controlled switch 14 will be in its closed state.
[0058] In the event the operator leaves the driver's scat and the feet of the
operator leave
pressure sensing mat 19 of pressure sensing mat system 17 when air pressure
controlled switch
14 is in its closed state, seat pressure switch 16 will move to its closed
state and the switching
function of pressure sensing mat system 17 will move to its closed state
whereupon electrical
power is provided by battery 2 to solenoid coil 20 via speed control 4, air
pressure controlled
switch 14, seat pressure switch 16, and the switching function of pressure
sensing mat system 17.
In response to energizing solenoid coil 20 with electrical power, air valve 22
terminates the
supply of pressurized air from air pressure source 10 to parking control valve
12, air pressure
controlled switch 14 and the vehicle parking brake(s). In response to
termination of pressurized
air thereto, air pressure controlled switch 14 moves to its open state and the
vehicle parking
brake(s) set to their fully "on" state.
[0059] It is to be appreciated that if the operator's feet leave pressure
sensing mat 19 of
pressure sensing mat system 17 while the operator is sitting on the driver's
seat, or if the driver
leaves the driver's seat while one or both of the driver's feet are still on
pressure sensing mat 19
of pressure sensing mat system 17, electrical power will be withheld from
solenoid coil 20
whereupon the vehicle parking brake(s) will not be set to their fully "on"
state. It is only when
the feet of the operator leave the pressure sensing mat of pressure sensing
mat system 17 and the
operator leaves the driver's seat that electrical power will be provided to
solenoid coil 20
whereupon the vehicle parking brake(s) are set to their fully "on" state.
[0060] With reference to the accompanying Fig. 2, another embodiment of an
anti-rollaway
device includes battery 2 coupled to supply electrical power to an
electrically actuated parking
control valve 12' via seat pressure switch 16 and a parking control switch 28.
[0061] Parking control valve 12' is operative for supplying or terminating the
supply of
pressurized air from air pressure source 10 to one or more brake(s) of the
vehicle in response to
energization or de-energization, respectively, with electrical energy from
battery 2.
[0062] The operation of the embodiment of the anti-rollaway device of Fig. 2
will now be
described.
[0063] In normal operation of the vehicle, in order to set the vehicle parking
brake(s) to the
fully "on" state, parking control switch is set to its open state whereupon
the supply of electrical
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power from battery 2 to parking control valve 12' is withheld. In response,
parking control valve
12 withholds the passage of pressurized air from air pressure source 10 to the
vehicle parking
brake(s). When it is desired to operate the vehicle, parking control switch 28
is set to its closed
state and seat pressure switch 16 is set to its closed state in response to
the operator sitting on the
driver's seat. The setting of seat pressure switch 16 and parking control
switch 28 to their closed
states enables parking control valve 12 to be energized with electrical power
from battery 2. In
response, parking control valve 12' permits pressurized air from air pressure
source 10 to pass to
the vehicle parking brake(s). In response, the vehicle parking brake(s) are
set to their fully "off'
state.
[0064] In the event the operator leaves the driver's seat when parking control
valve 12' is
passing pressurized air to the vehicle parking brake(s), seat pressure switch
16 will move to its
open state whereupon the supply of electrical power to parking control valve
12' from battery 2
is terminated. In response, parking control valve 12' terminates the supply of
pressurized air to
the vehicle parking brake(s).
[0065] If desired, speed control 4, (shown in phantom in Fig. 2) can be
coupled in series
between parking control valve 12' and battery 2. In the embodiment of the anti-
rollaway device
of Fig. 2, speed control 4 is operative for sensing the output of speed sensor
6 which outputs a
suitable signal indicative of the vehicle in motion. When the vehicle is in
motion above a
predetermined speed and speed sensor 6 is outputting a signal indicative
thereof to speed control
4, speed control 4 is operative for terminating or withholding the supply of
electrical power to
parking control valve 12' from battery 2 in order to avoid inadvertent
operation of parking
control valve 12' and, hence, the vehicle parking brake(s), when the vehicle
is in motion.
[0066] Desirably, in response to the vehicle coming to a stop, speed sensor 6
outputs a
corresponding signal to speed control 4 which is operative in response thereto
for passing power
from battery 2 to parking control valve 12' when switches 16 and 28 are in
their closed states.
[0067] While parking control valve 12' has been described as being operative
for supplying
or terminating the supply of pressurized air to one or more brake(s) of the
vehicle in response to
energization or de-energization, respectively, with electrical energy, it is
envisioned that parking
control valve 12' can also or alternatively be operative for supplying or
terminating the supply of
pressurized air to one or more brake(s) of the vehicle in response to de-
encrgization or
energization, respectively, with electrical power from battery 2. In this
case, the various open
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and closed states of switches 16 and 28 in the foregoing description of the
embodiment shown in
Fig. 2 would be reversed, as would the operation of speed control for
providing or withholding
the supply of electrical power to parking control valve 12' when the vehicle
is above or below
the predetermined speed.
[0068] It is envisioned that the embodiment of the anti-rollaway device shown
in Fig. 2 can
also include the switching function of pressure sensing mat system 17 in
series with seat pressure
switch 16. Inasmuch as the operation of the series combination of the
switching function of
pressure sensing mat system 17 and seat pressure switch 16 in the embodiment
of the anti-
rollaway device shown in Fig. 2 will be same as the operation of the series
combination of the
switching function of pressure sensing mat system 17 and seat pressure switch
16 in the
embodiment of the anti-rollaway device shown in Fig. I and described above, a
detailed
description of the operation of the series combination of the switching
function of pressure
sensing mat system 17 and seat pressure switch 16 in the embodiment of the
anti-rollaway device
shown in Fig. 2 will not be presented to avoid unnecessary redundancy.
10069] With reference to the accompanying Fig. 3, yet another embodiment of an
anti-
rollaway device includes battery 2 operative for supplying a positive voltage
to an input of a
logic inverter 34 via the series combination of parking control switch 28 and
scat pressure switch
16. In this embodiment, servo controlled brake(s) 12" are set to the fully
"on" or engaged state
in response to a parking control input 18 thereof being energized with a
sufficiently high positive
voltage from the output of inverter 34. Conversely, servo controlled brake(s)
12" are set to the
fully "off' or disengaged state in response to parking control input 18 being
coupled to a
sufficiently low voltage, e.g., near zero volts or ground, from the output of
inverter 34. When set
to the fully "off' state, servo controlled brake(s) 12" are operative under
the control of a servo
system 32 which is responsive to movement of a lever or pedal in the
operator's compartment of
the vehicle to provide a corresponding braking signal to an operational
control input 24 of servo
controlled brake(s) 12" to control the extent of actuation thereof as a
function of the extent of
actuation of the lever or pedal.
[0070] The operation of the embodiment of the anti-rollaway device of Fig. 3
will now be
described.
[0071] When it is desired to set servo controlled brake(s) 12" to the fully
"on" state, parking
control switch 28 is set to its open state whereupon the electrical connection
between battery 2
13
CA 02651403 2009-01-28
and the input of inverter 34 is terminated. In response, inverter 34 outputs a
suitable positive
voltage, e.g., positive battery voltage, to input 18 of servo controlled
brake(s) 12". In response,
servo controlled brake(s) 12" assume the fully "on" state.
[0072] Seat pressure switch 16 is operative for being in its closed state when
the operator is
sitting on the driver's seat and for being in its open state when the operator
is not sitting on the
driver's seat. In the event the operator leaves the driver's seat when parking
control switch 28 is
set to its closed state, i.e., the "off' state of servo controlled brake(s)
12", seat pressure switch 16
will move to its open state whereupon the electrical connection between
inverter 34 and battery 2
is terminated. In response, inverter 34 outputs a suitable positive voltage,
e.g., positive battery
voltage, sufficient to cause servo controlled brake(s) 12" to be set to the
fully "on" state.
[0073] To ensure inverter 34 outputs a low voltage or ground to input 18 of
servo controlled
brake(s) 12" during normal driving operation of the vehicle, whereupon servo
controlled brake(s)
12" are in the "off' state for control by servo system 32, speed control 4
(shown in phantom in
Fig. 3) can be coupled in parallel with the series combination of' seat
pressure switch 16 and
parking control switch 28. Like the embodiments discussed above, speed control
4 is operative
for sensing the output of speed sensor 6 (shown in phantom) which outputs a
suitable signal
indicative of the vehicle in motion. When the vehicle is in motion above a
predetermined speed
and speed sensor 6 is outputting a signal indicative thereof to speed control
4, speed control 4 is
operative for supplying a suitable positive voltage to the input of' inverter
34, regardless of the
state of seat pressure switch 16 and/or the state of parking control switch
28, whereupon inverter
34 outputs a low voltage to input 18 of servo controlled brake(s) 12",
whereupon said brake(s)
are set to the fully "off' state. As a result, inadvertent application of a
suitable positive voltage
by inverter 34 to input 18 of servo controlled brake(s) 12" and, hence, the
setting of servo
controlled brake(s) 12" to the fully "on" state, is avoided when the vehicle
is in motion above the
predetermined speed.
[0074] Desirably, in response to the vehicle coming to a stop, speed sensor 6
outputs a
corresponding signal to speed control 4 which is operative in response thereto
for terminating the
output of a suitable positive voltage to the input of inverter 34 and for
providing a high
impedance output to the input of inverter 34. As a result of this high
impedance output, the input
of inverter 34 is responsive to the operation of switches 16 and 28 to control
the supply of
positive voltage to the input of inverter 34 from battery 2. For example,
input 18 of servo
14
CA 02651403 2009-01-28
controlled brake(s) 12" receives a low voltage or ground from inverter 34 in
response to parking
control switch 28 being in its closed state and scat pressure switch 16 being
in its closed state in
response to the driver sitting on the driver's seat. As a result of this low
voltage, servo controlled
brake(s) 12" are set to the fully "oft' state. Conversely, when input 18 of
servo controlled
brake(s) 12" receives a suitable positive voltage from inverter 34 in response
to either one or
both of parking control switch 28 and seat pressure switch 16 being in its
open state, servo
controlled brake(s) 12" are set to their fully "on" state.
[0075] If the driver should leave the driver's seat when the vehicle is either
stopped or
moving below the predetermined speed where speed control 4 supplies a high
impedance output
to inverter 34 and the parking control switch is in its closed state, seat
pressure switch 16 will
move to its open state whereupon the positive voltage output by battery 2 to
the input of inverter
32 is terminated and, in response thereto, inverter 34 outputs a suitable
positive voltage to input
18 of servo controlled brake(s) 12", whereupon servo controlled brake(s) 12"
assume their fully
"on" state.
[0076] It is envisioned that the embodiment of the anti-rollaway device shown
in Fig. 3 can
also include the switching function of pressure sensing mat system 17 in
series with seat pressure
switch 16. Inasmuch as the operation of the series combination of the
switching function of
pressure sensing mat system 17 and seat pressure switch 16 in the embodiment
of the anti-
rollaway device shown in Fig. 3 will be same as the operation of the series
combination of the
switching function of pressure sensing mat system 17 and seat pressure switch
16 in the
embodiment of the anti-rollaway device shown in Fig. I and described above, a
detailed
description of the operation of the series combination of the switching
function of pressure
sensing mat system 17 and seat pressure switch 16 in the embodiment of the
anti-rollaway device
shown in Fig. 3 will not be presented to avoid unnecessary redundancy.
[0077] With reference to Fig. 4, another embodiment of an anti-rollaway device
includes the
various elements of the anti-rollaway device shown in Fig. I and further
includes an optional
handbrake control 42 that is connected in parallel with a conventional service
brake valve 44 of
the vehicle. Brake valve 44 operates in a manner known in the art to control
the amount or
pressure of pressurized air that is supplied to the service brake(s) of the
vehicle from air pressure
source 10 as a function of how far a brake pedal 45 of the vehicle is
depressed. Specifically,
when brake pedal 45 is not being depressed (i.e., brake pedal 45 is in its
fully up position), brake
CA 02651403 2009-01-28
valve 44 is closed whereupon pressurized air is withheld from the vehicle
service brake(s) and
the vehicle service brake(s) are set to their fully "off" state. In contrast,
when brake pedal 45 is
fully depressed, brake valve 44 is open whereupon pressurized air from air
pressure source is
provided to the vehicle service brake(s) and the vehicle service brake(s) are
set to their fully "on"
state. Activation of brake pedal 45, and hence brake valve 44, to a position
intermediate its fully
up position and its fully depressed position will result in the pressure of
the pressurized air
provided to the vehicle service brake(s) by brake valve 44 and, hence, the
state of the vehicle
service brake(s) being set intermediate their fully "off' state and their
fully "on" state. As is well
known in the art, the pressure of the pressurized air provided to the vehicle
service brake(s) is
related to the extent that brake pedal 45 is depressed.
[0078] Vehicles that service routes that require numerous stops are often
equipped with a
handbrake control 42 which enables the on/off state of the vehicle service
brake(s) to be
controlled independent of brake valve 44. Examples of such vehicles include
garbage trucks and
delivery vans. However, the invention is not to be construed as being limited
so such vehicles as
the invention can be utilized with any suitable and/or desirable vehicle that
has pressure operated
parking brake(s) and pressure operated service brake(s), e.g., without
limitation, a tractor/trailer.
[0079] Handbrake control 42 includes a lever 48 operated hand valve 46. Handle
48 is
disposed within easy reach of the operator, e.g., on the steering column of
the vehicle. I-land
valve 46 is connected in parallel with brake valve 44. When it is desired to
operate the vehicle
service brake(s) under the control of brake pedal 45 and brake valve 44, hand
valve 46 is set via
lever 48 to its closed state blocking the passage of pressurized air through
hand valve 46. In
contrast, when it is desired to utilize handbrake control 42 to set the
vehicle service brake(s) to
their fully "on" state, hand valve 46 is set via lever 48 to its open state
which shunts pressurized
air around brake valve 44 to the vehicle services brake(s) thereby setting the
vehicle services
brake(s) to their fully "on" state. Thus, when hand valve 46 is set to its
closed state, the vehicle
services brake(s) operate under the control of brake pedal 45 and brake valve
44 in a
conventional manner. In contrast, when hand valve 46 is set to its open state,
pressurized air is
provided to the vehicle service brake(s) which sets the vehicle service
brake(s) to their fully "on"
state.
[0080] A problem with handbrake control 42 is that when hand valve 46 is in
its fully open
state, lever 45 and/or hand valve 46 is/are subject to inadvertent movement,
e.g., due to
16
CA 02651403 2009-01-28
vibration, wear, or the operator inadvertently moving lever 45, whereupon hand
valve 46 moves
from its fully open state to a fully or partially closed state, whereupon the
pressure of pressurized
air supplied to the vehicle service brake(s) is terminated or reduced. If the
pressure of
pressurized air supplied to the vehicle service brake(s) decreases
sufficiently, the vehicle service
brake(s) can partially or fully disengage from the fully "on" state, whereupon
the vehicle can be
subject to uncontrolled movement (rolling).
[0081] To avoid the problem of inadvertent movement of hand valve 46 from its
fully open
state to a fully or partially closed state, a pressure sensing switch 40, in
the form of an on/off
switch, is positioned in a fluid supply line 50 that connects brake valve 44
and hand valve 46 to
the vehicle service brake(s). When the pressure of pressurized air in fluid
supply line 50 is above
a predetermined pressure, e.g., above 90 pound/square inch or 620.528 kPa,
pressure sensing
switch 40 will be in its open state. When the pressure of pressurized air in
fluid supply line 50
drops below this predetermined pressure, pressure sensing switch 40 will be in
its closed state.
[0082] The operation of the embodiment of the anti-rollaway device of Fig. 4,
without
optional pressure sensing mat system 17 shown in Fig. 4. will now be
described.
[00831 In normal operation of the vehicle, parking control valve 12 is set to
pass pressurized
air to air pressure controlled switch 14 and the vehicle parking brakes,
whereupon air pressure
controlled switch 14 will be in its closed state and the vehicle parking
brakes will be in their
"off' state. Hand valve 46 is set to its closed state, whereupon pressure
sensing switch 40 is in
its closed state, and the operator sits on the driver's seat causing seat
pressure switch 16 to be in
its open state. Under these conditions, electrical power is withheld from
solenoid coil 20 by the
open state of seat pressure switch 16 and the service brake(s) of the vehicle
are controlled by
brake pedal 45 and brake valve 44 in a conventional manner. In the event the
operator leaves the
driver's seat under these conditions, seat pressure switch 16 will close
whereupon solenoid coil
20 will receive electrical power from battery 2 thereby causing the vehicle
parking brake(s) to
move to their fully "on" state in the manner discussed above in connection
with the embodiment
shown in Fig. 1.
[0084] If, however, prior to leaving the driver's seat the operator moves
lever 48 to a
position that sets hand valve 46 to its fully open state, pressurized air
supplied to the vehicle
service brake(s) from air pressure source 10 via hand valve 46 sets the
vehicle service brake(s) to
their fully "on" state and sets pressure sensing switch 40 to its open state
as a result of the
17
CA 02651403 2009-01-28
constant supply of pressurized air above the predetermined pressure in fluid
supply line 50.
Thereafter, in response to the operator leaving the driver's seat, seat
pressure switch 16 will
move to its closed state. However, at this time, electrical power is withheld
from solenoid coil 20
by virtue of pressure sensing switch 40 being in its open state.
[0085] In the event the operator is not on the driver's seat when hand valve
46 moves from
its fully open state to a fully or partially closed state, whereupon the
pressure in fluid supply line
50 decreases below the predetermined pressure and the vehicle service brake(s)
fully or partially
release from their fully "on" state, pressure sensing switch 40 will close
thereby completing the
circuit between solenoid coil 20 and the negative terminal of battery 2. Under
these conditions,
solenoid coil 20 will receive electrical power from battery 2 thereby causing
the vehicle parking
brake(s) to move to their fully "on" state in the manner discussed above in
connection with the
embodiment shown in Fig. 1.
[0086] When the vehicle parking brake(s) are set to their fully "on" state in
response to
solenoid coil 20 being energized with electrical power from battery 2, parking
control valve 12
terminates the supply of pressurized air to air pressure controlled switch 14,
whereupon air
pressure controlled switch 14 will move to its open state thereby preventing
solenoid coil 20
from being energized and unnecessarily draining battery power when the vehicle
parking
brake(s) are set to their fully "on" state.
[0087] As discussed above, parking control valve 12 includes a mechanical
interlock that
prevents parking control valve 12 from passing pressurized air to air pressure
controlled switch
14 and the vehicle parking brake(s) absent manipulation of activation means 13
by a vehicle
operator in a suitable manner. Thus, when the supply of pressurized air to
parking control valve
12 is terminated in response to energizing solenoid coil 20 in the manner
described above, when
the pressure of the pressurized air to air pressure controlled switch 14
decreases to the point that
air pressure controlled switch 14 opens, whereupon solenoid coil 20 is de-
energized and air valve
22 once again permits pressurized air to flow to parking control valve 12, the
mechanical
interlock of parking control valve 12 prevents the passage of pressurized air
to air pressured
controlled switch 14, thus avoiding the uncontrolled on/off' operation of the
vehicle parking
brake(s) as a result of the alternating supply and termination of pressurized
air to air pressure
controlled switch 14 in response to air valve 22 passing and not passing
pressurized air to
parking control valve 12.
18
CA 02651403 2009-01-28
[00881 The operation of the embodiment of the anti-rollaway device shown in
Fig. 4 with air
pressure controlled switch 14, seat pressure switch 16, pressure sensing
switch 40, and optional
pressure sensing mat system 17 will now be described.
[00891 Assume that the operator is sitting on the driver's seat with one or
both feet of the
operator on pressure sensing mat 19 of pressure sensing mat system 17 and with
parking control
valve 12 set to pass pressurized air to air pressure controlled switch 14.
Under these conditions,
seat pressure switch 16 will be in its open state, the switching function of
pressure sensing mat
system 17 will be in its open state, and air pressure controlled switch 14
will be in its closed
state. Assume further that hand valve 46 of handbrake control 42 is in its
closed state whereupon
pressure sensing switch 40 is in its closed state. With switches 14, 16 and 40
and the switching
function of pressure sensing mat system 17 in the foregoing states, the
operation of the vehicle
service brake(s) can be controlled by the operator via brake pedal 45 and
brake valve 44 in a
conventional manner.
[00901 Under these conditions, if the operator leaves the driver's seat and
the feet of the
operator leave the pressure sensing mat 19 of pressure sensing mat system 17,
seat pressure
switch 16 and the switching function of pressure sensing mat system 17 will
move to their closed
states whereupon electrical power will be provided to solenoid coil 20 via
speed control 4, the
closed state of air pressure controlled switch 14, the closed state of seat
pressure switch 16, the
closed state of the switching function of pressure sending mat system 17, and
the closed state of
pressure sensing switch 40. In response to energizing solenoid coil 20 with
electrical power, air
valve 22 terminates the supply of pressurized air to parking control valve 12
whereupon the
supply of pressurized air to air pressure controlled switch 14 and to the
vehicle parking brake(s)
is terminated. In response to termination of pressurized air thereto, the
vehicle parking brake(s)
are set to their fully "on" state. The mechanical interlock of parking control
valve 12 prevents
the reintroduction of pressurized air to the vehicle parking brake(s) absent
the operator
manipulating activation means 13 in a suitable manner that enables parking
control valve 12 to
pass pressurized air to the vehicle parking brake(s) and to air pressure
controlled switch 14.
100911 Assume now that the operator of the vehicle moves hand valve 46 to its
fully open
state when the operator is sitting on the driver's seat and/or when one or
both feet of the operator
is/are on pressure sensing mat 19 of the pressure sensing mat system 17, and
when parking
control valve 12 is passing pressurized air to air pressure controlled switch
14 and to the vehicle
19
CA 02651403 2009-01-28
parking brake(s). With hand valve 46 in its fully open state, the vehicle
service brake(s) are set
to their fully "on" state and pressure sensing switch 40 is set to its open
state by the pressurized
air in fluid supply line 50. Under these conditions, pressure sensing switch
40, seat pressure
switch 16 and the switching function or pressure sensing mat system 17 will be
in their open
states, and air pressure controlled switch 14 will be in its closed state. If
the operator then leaves
the driver's seat and the feet of the operator leave pressure sensing mat 19
of the pressure
sensing mat system 17, seat pressure switch 16 and the switching function of
pressure sensing
mat system 17 will move to their closed states. However, since the vehicle
service brake(s) are
to their fully "on" state by the pressurized air in fluid supply line 50 and
since pressure sensing
switch 40 is set to its open state by the pressurized air in fluid supply line
50, automated
activation of the vehicle parking brake(s) in the manner described above will
not occur due to the
open state of pressure sensing switch 40. Under these conditions, hand valve
46 passing
pressurized air to the vehicle service brake(s) via fluid supply line 50
prevents inadvertent
movement of the vehicle.
[00921 Under these conditions, in the event hand valve 46 moves from its fully
open state to
a fully or partially closed state, the air pressure in fluid supply line 50
will drop and the vehicle
service brake(s) will fully or partially release from their fully "on" state .
Should the air pressure
in fluid supply line 50 drop below the predetermined pressure. pressure
sensing switch 40 to
move from its open state to its closed state whereupon electrical power will
be provided to
solenoid coil 20 via speed control 4, the closed state of air pressure
controlled switch 14, the
closed state of seat pressure switch 1 6, the closed state of pressure sensing
switch 40, and the
closed state of the switching function of pressure sensing mat system 17. In
response to
energizing solenoid coil 20 with electrical power, air valve 22 terminates the
supply of
pressurized air to parking control valve 12 whereupon the supply of
pressurized air to air
pressure controlled switch 14 and to the vehicle parking brake(s) is
terminated. In response to
termination of pressurized air thereto, the vehicle parking brake(s) are set
to their fully "on"
state. The mechanical interlock of parking control valve 12 prevents parking
control valve 12
from inadvertently passing pressurized air to air pressure controlled switch
14 and the vehicle
parking brake(s) absent manipulation of activation means 13 by the operator of
the vehicle.
Thus, once the vehicle parking brake(s) are set to their fully "on" state in
response to air valve 22
terminating the supply of pressurized air from air pressure source 10 to
parking control valve 12,
CA 02651403 2009-01-28
pressurized air can only be reintroduced to air pressure controlled switch 14
and to the vehicle
parking brake(s) by operator manipulation of activation means 13, thus
avoiding the inadvertent
on/off operation of the vehicle parking brake(s) in the absence of such
mechanical interlock.
[0093] As can be seen in the embodiment of the anti-rollaway device shown in
Fig. 4,
pressure sensing switch 40 enables the vehicle parking brake(s) to be set to
their fully "on" state
in response to the full or partial release of the vehicle service brake(s)
resulting from a reduction
in the pressure of the pressurized fluid supplied to the vehicle service
brake(s) via hand valve 46.
[0094] While the embodiment of the anti-rollaway device shown in Fig. 4 has
been described
with reference to the use of pressure sensing switch 40, it is envisioned that
any suitable and/or
desirable sensing means which can sense the air pressure inside fluid supply
line 50 above and
below the predetermined pressure and which can perform the switching function
of pressure
sensing switch 40, and/or any suitable and/or desirable means that enables
detection of the
position of the open state or fully/partially-closed state of hand valve 46,
either directly or via
lever 48, and which can perform the switching function of pressure sensing
switch 40 can also or
alternatively be used.
[0095] While the embodiments described in connection with Figs. 1, 2, and 4
have been
described in connection with pressurized air, it is to be appreciated that
these embodiments can
alternatively utilize pressurized hydraulic fluid. Accordingly, the foregoing
description of the
embodiments utilizing pressurized air is not to be construed as limiting the
invention.
[0096] Because the automated activation of the vehicle parking brake(s) in
each of the
forgoing embodiments of the anti-rollaway system involves an electrical signal
(even just a
pulse), it is envisioned that information regarding the event, such as the
time, date, and
geographic position of the event, can be recorded in any suitable and/or
desirable manner, such
as, without limitation, via an optional alarm/recording means 26 (shown in
phantom in Figs. I
and 4) that can be connected to be energized when solenoid coil 20 is
energized. Information
regarding the event can then recovered from alarm/recording means 26,
whereupon management
can be alerted to accidents that were avoided that day and perhaps the need
for additional driver
training or in some cases mandatory safety education or even imposition of
economic deterrents.
[0097] Alarm/recording means 26 can include suitable means known in the
electronics,
instrumentation, and process control industries (e.g. UPS, mobile telephone)
for recording the
activation of the anti-rollaway device and for associating such activation
with a date, time, and
21
CA 02651403 2009-01-28
geographic position of the vehicle when the activation occl.irred.
Alarm/recording means 26 can
further include wired means (e.g., a USB port) and/or wireless means (e.g., RF
communication
via a mobile telephone network or satellite network) for recovering such
information at regular
intervals and/or pre-determined times including, including but not limited to
the time of
occurrence of the activation of the anti-rollaway system. Alarm/recording
means 26 can further
include means for preventing tampering with or altering such information other
than by well-
defined established procedures external to the operation of'the vehicle.
[0098] The alarm function of alarm/recording means 26 can be connected to be
energized
when solenoid coil 20 is energized whereupon said alarm function is activated
when solenoid
coil 20 is energized. The alarm function of alarm/recording means 26 can be an
audible alarm
and/or a visual alarm.
[0099] It is to be appreciated that the alarm function and recording function
of
alarm/recording means 26 can be provided independent of each other. Thus, the
foregoing
description of the alarm/recording means 26 as having a combined alarm
function and recording
function is not to be construed as limiting the invention.
[0100] The present invention has been described with reference to the
preferred
embodiments. Obvious modifications and alterations will occur to others upon
reading and
understanding the preceding detailed description. For example, if desired, any
one or all of the
foregoing embodiments of the anti-rollaway device can include a fuse or switch
(shown in
phantom in Figs. 1 and 4) in series with the supply of battery power to the
anti-rollaway device.
Accordingly, if it is desired to disable the anti-rollaway device for any
reason, e.g., towing of the
vehicle, the fuse can be removed or the switch can be set to an open position
whereupon the anti-
rollaway device will not receive electrical power from battery 2. Moreover,
the various logic
conventions for the disclosed embodiments are not to be construed as limiting
the invention since
it is envisioned that any suitable and/or desirable logic convention that
enables operation of the
various disclosed embodiments is envisioned. The invention is intended to be
construed as
including all such modifications and alterations insofar as they come within
the scope of the
appended claims or the equivalents thereof.
22
