Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
BACKGROUND OF THE INVENTION
This invention relates generally to vehicles and D re
particularly to vehicles having both a primary motor and an
auxiliary motor.
As is well known, conventional vehicles such as passenger
cars sometimes become stalled in mud or snow or on ice when the
drive wheels, usually the rear wheels, lose traction. With the
increasing popularity of compact passenger vehicles, traction
~problems under such adverse conditions have become more common.
Com~act and subcompact v~ehicles are specially designed to be
light in weight and traction problems are therefore inherent.
Furthermore, compacts and subcompacts generally have small tires
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and wheels which, as is well known, have relatively high rolling
resistance. The increased use of plastics and other lightweight
materials in these and other vehicles has made such traction
problems even more widespread.
Traditional passenger cars having two-wheel drive are
especially susceptible to stalling under adverse road conditions.
It has long been known that full-time four-wheel-drive vehicles,
such as military or recreational vehicles, are especially adapted
for travel under adverse road conditions. Such full-time four- -
wheel-drive vehicles are adapted with front and rear drive axles
operatively and drivingly connected to a single mover such as a
gasoline engine. Vehicles have also been designed with part-time
four-wheel-drive capabilities. In these vehicles wheel locks or
clutches are manually or automatically selectively engageable to
transform the vehicle from a two-wheel-drive to a four-wheel-drive
system. Although full or part-time four-wheel-drive vehicles
have proved highly successful in specific situations, the large
drive mechanisms used in these vehicles are generally unsuitable
in size and weight for the presently popular compact and subcompact
vehicles.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a
vehicle having a lightweight auxiliary drive system.
It is a further object of the ~resent invention to provide
a vehicle having a primary mover and an auxiliary mover.
It is still a further object of the present invention
to provide a vehicle which is selectively driveable through two
axles.
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These and other objects of the present invention which
will become apparent from the following detailed description are
achieved by a vehicle having a primary mover adapted for driving
engagement with a first axle which is drivingly engaged with a
first wheel. The vehicle further comprises a secondary mover
drivingly engaged with a second axle which is selectively drivingly
engageable with a second wheel. Preferably, the secondary mover
comprises an electric motor which is operable in two directions.
The secondary mover may be manually actuatable by the vehicle
operator and automatically disengageable upon the vehicle reaching
a predetermined speed. The secondary mover may be driven by the
primary mover or may be operable from an independent power source
such as a battery. The second axle is a dead axle when the
secondary mover is inoperative. The second wheel therefore
comprises means for overrunning the second axle, preferably in
two directions.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is an isometric view of a vehicle having the
auxiliary drive system of the present invention, a portion of the
vehicle being broken away to show the chassis components.
Figure 2 is a rear elevation view of the rear wheel and
axle assembly of the vehicle of Figure 1.
Figure 3 is a cross-sectional elevation view of the right
rear wheel end assembly of the axle in Figure 2.
Figure 4 is a schematic diagram of an electrical circuit
for the auxiliary drive system of the present invention.
DETAILED DESCRIPTION OF A PRESENTLY PREFERRED EMBQDIMENT
Referring to Figure 1, a subcompact passenger vehicle 10
is shown having a frame 12 upon which is secured the vehicle
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body 14. The vehicle 10 has a forward mo~mted primary mover 20
which is a gasoline engine in the presently preferred em~odiment.
Power for starting the engine 20 is supplied by a twelve volt
battery 18. Much of the electrical system for starting the
engine 20, as for instance the starter and associated wiring, has
not been illustrated in Figure 1 as it is well known in the art.
An electrical generator 19, driven by the engine 20, is adapted to
recharge the battery 18 through a voltage regulator 21 and to
supply electrical power to various electrical accessories in the
vehicle such as a radio, heater, lights, etc.
In the presently preferred embodiment, a manual transmission
22 is drivingly connected to the engine output shaft (not shown).
It should be noted, however, that the present invention may
readily be utilized with a vehicle having an automatic trans-
mission. A transmission output shaft 23 extends downwardly fromthe bottom of the transmission 22 into a right angle differential
unit 24. Right and left front drive axles 25 and 26 are drivingly
engaged with the transmission output shaft 23 through the drive unit
24 and with the front drive wheels 27. The transmission 22 permits
both forward and reverse drive of the axles 25 and 26 as is well
known~in the art. The mechanism for steering the front wheels 27
is not illustrated in Figure 1 as it too is well known in the art.
As can more clearly be seen in Figure 2 the vehicle 10 has
a selectively drivable rear axle assembly 34 contained within a
rear axle housing 36 which extends between the right and left rear
wheels 37 and 37'.
The rear axle housing 36 is bent upward near the center
of the vehicle to provide additional ground clearance, but it
should be understood that a straight axle is within the scope of
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the present invention. The right side of the axle assembly 34
includes right axle shafts 35, 4~ and 50 (see Figure 3) drivingly
connected in series by universal joints 46 and 47. The left side
of the axle assembly 34 comprises an identical series of axle
shafts, including shaft 35', which operate in a manner similar
to the right side of the axle assembly.
A secondary, electric motor 40 is rigidly affixed to the
rear portion of the frame 12 above the rear axle assembly 34 by
brackets 39. The frame 12 is connected to the rear axle housing
36 by rear springs 33 and 33' which act to cushion the frame and
the secondary mover 40 from jolts due to adverse road conditions.
A telescoping slip shaft 42 (see also Figure 1~ extends
from the electric motor 40 into a right angle drive unit 44.
The shaft 42 is adapted to accommodate any variation in distance
between the motor 40 and the axle housing 36, such as those caused
by adverse road conditions. The shaft 42 should be designed to
telescope a distance as required to accommodate anticipated axle
movement.
The drive unit 44 includes a housing 45 integral with the
axle housing 36. The drive unit 44 comprises a worm gear 41
rigidly connected to the axle shafts 35 and 35'. The worm gear
41 is thereby adapted to drive both the right and left wheels
37 and 37' as will be described. The unit 44 also comprises a
worm 43 operati~ely drivingly engaged with the worm gear 41.
The worm 43 is affixed to the telescoping shaft 42 which extends
from the motor 40 and is adapted to be driven thereby.
It should be noted that other types of drive systems can
easily be adapted to replace the drive unit 44. For instance,
other types of gearing such a spiroid, helicoid, or planetary
gearing could be used, as well as belt or chain drive systems
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either alone or in combination with gearing. The worm and worm
gear system disclosed is presently preferred because of its
high torque ratio.
When the electric motor 40 is inoperative, the entire
axle assembly 34, including the axle shafts 35, 35', 48 and 50,
remains stationary. In other words, the axle assembly 34 is
normally a "dead" axle. The associated rear wheel end assemblies
must therefore be adapted to permit free rotation of the rear
wheels 37 and 37' when the rear axle is stationary.
Reerring to Figure 3, the right end axle shaft 50 has
right hand threads 52 near its outer end portion. The wheel end
assembly 53 includes a stationary member 54 which is rigidly secur-
ed to the axle housing 36 and which contains a set of bearings 49
for radially aligning the axle shaft 50.
A threaded steel input clutch member 55 is screwed onto the
threaded outer portion of the axle shaft 50. The input clutch
55 has two frusto conical surfaces 59 and 60, each tapering away
from the other. The stationary member 54 has an annular protub-
erance 51 extending axially outwardly toward the wheel 37. An
annular drag spring 56 is rigidly secured to the protuberance 51
and is slidably engaged with an annular axially inward extension
57 of the input clutch member 55.
A two piece output clutch is rigidly connected to the right
rear wheel by means (such as bolting) well known in the art. The
output clutch members 58 and 68 are held rigidly together by a
clip 78. Together the members 58 and 68 define a cavity 61 in
which the input clutch member 55 is contained. The output clutch
member cavity 61 is defined in part by two frusto conical clutch-
ing surfaces. Surface 69 on clutch member 68 and surface 70
on member 58 are adapted for frictional engagement with the
input clutch member surfaces 59 and 60, respectively. The output
clutch is made in two components 58 and 68 to permit insertion
of the input clutch 55 within the output clutch cavity 61. Output
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clutch member 58 also houses a bearing assembly 71 for radially
allgni.ng the shaft 50. The housing member 36 houses a bearing
assembly 79 for radially aligning the output clutch member 58.
When the axle shaft 50 is driven in a forward direction (as
indicated by the arrow 61 in Figure 3) the input clutch member 55
is held rotationally stationary by the drag spring 56. The
clutch member 55 is therefore screwed outwardly (rightwardly as
viewed in Figure 3) on the input shaft 50 towards the wheel 37
until the input clutching surface 60 frictionally engages the
output clutching surface 70. At this point the input clutch
member 55 is locked between the input shaft 50 and the output
clutch member 58. The locked driving relationship between these
members exists as long as the output clutch member 58 continues
to drive the wheel 37. In this condition the drag spring force
is overcome by the driving forces and the input clutch rotates
with the shaft 50 and wheel 37.
If the driving force applied by the axle shaft 50 should
cease, as for example by stopping the auxiliary motor 40 or by
~rotating the wheel 37 faster than:the rotation of the input shaft
50, the wheel 37 is free to overrun the input shaft 50. When
the wheel 37 overruns the shaft 50, the output clutch member 58
turns the input clutch member 55 in the forward direction 61
relative to the shaft 50 because of the frictional engagemen~ of
: the clutch members 55 and 58. The output clutch member 58 there-
fore moves the input clutch member 55 axially inwardly on the
threaded shaft 50, disengaging the clutch surfaces 60 and 70.
As the input shaft 50 continues to rotate, the drag spring
56 holds the input clutch member 55 rotationally stationary
causing it to reverse its direction and move axially outwardly
toward the wheel 37, thereby re-engaging the output clutch
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member 58. If the rotational speed of the input shaft 50 is
less than that of the output clutch member 58, the input member
55 will be bumped out of engagement each time the drag spring
56 and the shaft 50 attempt to engage the surfaces 60 and 70.
If the wheel 37 slows to a speed less than that of the shaft 50,
the clutch surfaces 60 and 70 are re-engaged as previously
described and the wheel is again driven.
When the auxiliary motor is stopped for any reason, the
input shaft 50 will also stop and the wheel 37 will overrun the
input shaft 50 as just described. As the wheel 37 continues to
-~ rotate it disengages the input clutch member 55 from the output
clutch member 58. Because the shaft 50 is stopped, the drag
spring 56 retains the clutch member 55 between the surfaces 69 and
70 of the output member 58 and no bumping occurs between the
members 55 and 58
A reverse rotation of the axle shaft 50 causes engagement
of the clutch surfaces 59 and 69 whereby the wheel 37 is driven
in the reverse direction. Overru~ing in the reverse direction is
accomplished similarly to that in the forward direction.
It should be noted that the wheel end assemblies will be
operative regardless of whether the wheel end shafts such as 50
have right or left hand threads, as this will only change which
clutching surfaces are engaged for orward and reverse operation.
It should also be noted that the wheel end assemblies 53 and 53'
are essentially identical and simultaneously drive the wheels 37
and 37', respectively. Because of the overruning capabilities of
each assembly 53 and 53', no differential gearing is necessary,
as the slow wheel will always be driven while the faster wheel
overruns.
The preferred auxiliary motor circuit is provided with
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means for disengaging the input clutch member 55 from the out-
put clutch members 58 or 68 when the auxiliary motor 40 is de-
activated. Disengagement of the clutch members is accomplished
by momentarily rotating the wheel end shaft 50 in the direction
opposite that in which it was driving. This brief rotation, one-
quarter turn for example, in the opposite direction assures that
the input clutch member 55 frees itself from locking frictional
engagement with the output clutch. Such a locking condition
could cause the entire system to be backdriven, possibly resulting
in damage to the system. The presently preferred electrical
circuit for accomplishing this disengagement will be described
hereinafter.
Referring again to Figure 1, the auxiliary electric motor
40 is electrically connected directly to the battery 18. It is
therefore possible for the auxiliary motor 40 to be driven for
short periods by the battery 18 without the engine 20 being in
operation. An auxiliary motor on/off switch 66 interrupts the
electrical line 62 and is conveniently located in the vehicle
operator's compartment. It is sufficient for most anticipated
situations that the battery 18 be operative to move the vehicle
at a speed of about 5 m.p.h. for a distance of up to two to
three hundred yards before requiring a recharge. However, if the
engine 20 is running, the generator 19, through the voltage
regulator 21, continuously recharges the battery 18 and the
electric motor 40 is in effect driven by the primary mover.
Alternatively, the electric motor 40 may be electrically connected
directly to the voltage regulator 21 and generator 19 by the wires
64 shown in phantom in Figure 1. In this alternative mode the
secondary mover 40 can be activated only when the primary mover
20 is in operation.
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In the presently preferred embodiment the auxiliary drive
motor 40 is a 12 Volt DC reversible split series electric motor.
It may be run in either the forward or reverse direction. The
motor 40 is controlled by a relay logic system using a multitude
of relays, switches, diodes, capacitors and system status lights.
A preferred electrical circuit for operation of the auxiliary
motor system of the presently preferred embodiment is illustrated
in Figure 4.
In Figure 4, all relays are depicted as coils and are
denoted "R" (e.g. R-l, R-2, etc.). Each relay is operativè to
act upon a corresponding set of contact points denoted "CR" (e.g.,
CR-l, CR-2, etc.).
Power to the electric motor 40 is supplied from the positive
terminal of a 12-volt buss battery. To activate the auxiliary
electric motor 40, the ON SWITCH must momentarily be depressed
to complete the circuit. This activates the SYSTEM-ON LIGHT.
Current from the battery flows through relay R-l which closes the
normally open contact CR-l and allows current from the battery
to flow through relays R-2 and R-3. Normally open contact CR-2
is therefore closed, bypassing the ON SWITCH after it springs to
its normally open position. The auxiliary system can thereby
cperate without the ON SWITCH being closed throughout operation.
Current through relay R-3 simultaneously closes normally open
contact CR-3 and opens normally closed contact CR-3' which effects
a charging of the JOG AND SWITCH capacitor. The operation of the
JOG AND SWITCH portion of the circuit will be described herein-
after.
Before current can reach the motor 40, it must pass
through the OFF SWITCH and the MOTOR OVERSPEED SWITCH, which
are both normally closed, to the normally open contact CR-9.
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Contact CR-9 is closed by relay R-9 when it is activated by
current passing from the battery through the OVER-TEMPERATURE
SWITCl~. The OVER-TEMPERATURE SWITCH is normally closed unless
the motor 40 overheats. Current must also pass through normally
closed contact CR-5 which may be opened by relay R-5 if the
vehicle brake pedal is depressed, or by closing the CLUTCH
SWITCH. In a vehicle having an automatic transmission the
CLUTCH SWITCH would of course be omitted.
On its path to the auxiliary motor 40 current must pass
through the THROTTLE SWITCH, which is closed by a slight
depressing of the throttle, to the normally open contact CR-10.
Relay R-10 closes the contact CR-10 when the IGNITION SWITCH is
closed by the vehicle operator turning the vehicle ignition to
the "on" position.
With all of the previously mentioned switches and contacts
closed the current can reach the contacts CR-6 which is normally
closed and CR-6' which is normally open. When the electric
motor 40 is operated in the forward mode the contact CR-6 remains
closed with the current thereby passing through the diodes D-l
and D-2. Current passing through diode D-l charges the REVERSE
JOG capacitor. Current passing through the diode D-2 activates
relay R-8 which closes the contact CR-8. Current is then per-
mitted to pass through relay MR-F which closes contact CMR-F,
thereby completing a current path from the battery to the
FORWARD terminal of the tor 40.
To operate the electric motor 40 in the reverse mode, the
manual transmission 22 is shifted into reverse. The reverse
setting in the transmission closes the BACKUP LIGHT SWITCH,
thereby activating the relay R-6 which opens the contact CR-6
and closes the contact CR-6'. Current is therefore prevented
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from passing through diodes D-l and D-2 and is permitted to
pass through the diodes D-3 and D-4. Current passing through
diode D-3 charges the FORWARD JOG capacitor. Current passing
through the diode D-4 activates the relay R-7 which closes
the normally open contact CR-7. The relay MR-R is therefore
activated, which closes the contact CMR-R and completes the
circuit to the REVERSE terminal of the electric motor 40 and
drives the motor in the reverse direction.
Several safety features are built into the auxiliary motor
circuit as illustrated in Figure 4. For example~ the IGNITION
SWITCH must be turned on before the system can be activated.
Furthermore, as previously described, the operator must be
touching the accelerator pedal to close the THROTTLE SWITCH and
must be partially engaging the clutch to open the CLUTCH SWITCH.
If any of these switches change position during operation of
the auxiliary motor 40, current flow to the motor will immediately
cease. It can therefore be seen that the vehicle operator must
be in the driver's seat and poised for operation of the vehicle
before the system can be activated. The safety features allevi-
ate the problems of an inadvertent switching on of the auxiliarysystem which may cause an accident if the vehicle is in a location
with narrow clearance, such as a garage or in heavy traffic.
Further safety factors are also built into the auxiliary
motor circuit. For example, the centrifugal MOTOR OVERSPEED
switch breaks the circuit, therefore cutting off current flow
to the motor 40, when the motor reaches a predetermined speed.
Heating of the motor over a predetermined temperature causes
the OVER-TEMPERATURE SWITC~ to open, thereby deactivating the
relay R-9 which closes the contact CR-9', illuminating the
OVER-TEMPER~TURE LIGHT, and opening contact CR-9 thereby termin-
ating current flow to the motor 40.
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As previously noted, when the electric motor is activated
in either the forward or reverse direction, the ~EVERSE JOG or
the FORWARD JOG capacitor, respectively, is charged. Current
ceases to flow through relay R-3, when the circuit leading to
the electric motor 40 is broken, as for example by the OVERSPEED
SWITCH, OVERTEMPRATURE SWITCH, or OFF SWITCH. Contact CR-3
therefore returns to its normally open position while contact
CR-3' returns to its normally closed position. The charged
JOG AND SWITCH capacitor discharges through the relay R-4 which
momentarily closes the normally open contacts CR-4. The charged
REVERSE JOG or FORWARD JOG capacitor therefore discharges
through the relay R-7 or R-8, respectively. The pulse of
current passing through the relays R-7 or R-8 momentarily closes
the contact CR-7 or CR-8, respectively. This permits a pulse
of current to momentarily drive the electric motor 40 in the
reverse or the forward direction, respectively, thereby dis-
engaging the wheel end clutch assembly as previously described.
Under actual driving conditions, if front wheel of the
vehicle 10 of the present invention is stalled on ice for example,
the auxiliary system may be utilized. To activate the system the
driver leaves the ignition switch on, slightly touches the
throttle, and begins to release the clutch. He then depresses
the auxiliary SYSTEM-ON SWITCH, with the SYSTEM-ON LIGHT indicat-
ing such, which fully connects the circuit of the auxiliary drive
motor 40. Rotation of the motor 40 then begins in the selected
direction with the motor 40 driving the rear axle as previously
described.
When the vehicle is out of the road incumberance, the
auxiliary motor 40 may be deactivated by the OFF SWITCH which
breaks the auxiliary motor circuit shown in Figure 4. If the
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driver fails to manually deactivate the system, the MOTOR
OVERSPEED SWITCH automatically breaks the circuit when the
auxiliary motor reaches a predetermined speed. The BRAKE SWITCH
will also deactivate the system upon a slight touching of the
brake pedal.
It should further be noted that the auxiliary system of
the present invention may be modified such that the auxiliary
motor 40 is automatically activated upon slippage of the drive
wheels, Such an automatic auxiliary drive system requires means
for determining when the front drive wheels are slipping. One
such means is a wheel speed sensing device such as a magnetic
pickup 70 (illustrated in phantom in Figure 1) which "reads"
equally circumferentially spaced teeth, ridges or other surface
deviations 71 on the drive wheel 27 or on a ring attached thereto.
Output from the sensor is fed through a logic portion 72 of the
system which compares wheel speed changes with a predetermined
programed permissible speed variation range. Upon deviation from
the permissible range the logic 72 activates a switch 73 which
connects the wires 62, thereby completing the circuit from the
battery 18 to the auxiliary motor 40. The logic 72 is also
adapted to open the switch 73 when the wheel slip condition is
terminated. Wheel speed sensing devices as described are presently
utlized on anti-skid braking systems which are presently avail-
able for passenger automobiles and trucks. Such anti-skid braking
systems could easily be adapted to automatically activate the
auxiliary motor system of the present invention.
It should be noted that other types of auxiliary motors
such as hydraulic pump/motors may be utilized in the vehicle
of the present invention. Hydraulic pump/motors are well known
in the art and have often been utilized in systems involving
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vehicle power transmission. Hydraulic auxiliary movers generally
derive their power from the primary motor and thereby may only
be utilized in applications when such derivitive power is
sufficient. However, hydraulic pump/motors may be switched from
S a forward drive direction to reverse drive direction merely by
the switching of hydraulic valve.
The structure previously described has been for the purpose
of illustrating a presently preferred embodiment of the invention.
It should be understood that many other modifications or altera-
tions may be made without departing from the spirit and the scope
of the invention as set forth in the appended claims.
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