Note: Descriptions are shown in the official language in which they were submitted.
1 -
VEHICLE WITH CLUTCH/BRAKE INTERLOCK
The invention relates to a vehicle having a
clutch/brake interlock control system ~or assisting a
driver when starting a vehicle on a hill.
When a vehicle with a conventional gear shift is
started on a hill, the driver must ensure that the
clutch is not engaged prematurely before the brake is
released, other~rise the engine stalls, and that the
brake is not released prematurely before the clutch is
engaged, otherwise the vehicle rolls backwards.
Accidents can thus occur, particularly with a new or
inexperienced driver, who may well be under stress
when driving up a hill.
It is the objec-t of the invention -to provide a
clutch/brake interlock system which assists a driver
operating a vehicle on a hill.
In accordance with tl~e present inven-tion, a
vehicle having a clu-tch for engaging and disengaging
a drive transmission -to at least one driven wheel of -the
vehicle; and a duct for conveylng pressurised brake
:Eluid from a source to at least one wheel brake
cylinder, for brake engagement is characterised by a
a clutch/brake interlock control system comprising a
valve in the brake fluid duct, the valve having a
closure member which is urged by a spring towards a
seat to close the duct but which can then be moved awav
from the seat by excess pressure ~rom the source to
allow fluid flow to the brake cylinder to increase
braking pressure; and a solenoid device for o~erriding
the valve spring, the device being energised under the
control of an actuator of the clutch such that when the
transmission is disengaged the valve closure member is
free -to move onto the seat bu-t when the transmission
is engaged the valve closure member is moved away from
the seat to open the valve and hence allow release of
the brake.
With this arrangement, when the vehicle is
started on a hill, -the brake is not released until the
clutch is engaged, but the brake can be engaged when
necessary at all timesO
Preferably, the brake fluid pressure in the duct
down stream of the valve acts on -the valve closure
member to provide a force -tending to hold the valve
closed; and an equilibrium member ~hich is also
subjected to the brake ~luid pressure in the duct down-
stream of the valve acts on the valve closure member
through the valve seat to compensate -the force~ ~
Irrespective of the brake fluid pressure trapped in the
brake cylinderl a comparati~ely weak spring is then
sufficient to open the valve when the clutch is
engaged.
In a pa~ticular construction, the valve closure
member is moun-ted on a valve rod which passes through
an armature o~ the solenoid, the arma-ture being loaded
by a spring to move in a direction to engage the rod
and draw the valve closure member off the sea-t when
a coil o~ the solenoid is unenergised, but moving to
release the valve rod and closure member upon energis-
~tl~n of the coil when the clutch ac-tuator is operated
to engage the tr~n~mi~sion.
An example o~ the relevant part o~ a vehicle con~
~2~
-- 3 -- -
structed in accordance with the presen-t invention is
illustrated diagrammatically in the accompanying
drawings, in which:-
Figure 1 i.s an axial section through the con-trol
system;
Figures 2, 3, and 4 are views similar to Figure 1
but to a smaller scale and showing the system in
different operating con~igurations;and,
Figure 5 is a section -taken partly on -the line
V-V and partly on the line VI-VI in Figure 1.
As shown in the drawings, the vehicle has a
clutch/brake interlock control system generally indi-
cated by the reference numeral 1. The system
incorpora-tes a body 25 incorporating a through duct
Pormed by a connection 10 to a source of pressurised
brake fluid, the connection 10 leading -through an
upstream duct part 13, a valve sea-t 12, a chamber 24,
a downstream duct par-t 13a, and a connection 11 -to a
wheel brake cylinder~ The top of the chamber 24 is
closed by a flanged body 7 on which is mounted a
housing cap 40 The cap 4 supports a spool 3 on which
is mounted a solenoid coil 3. A :Erus-to-conical valve
closure member 5 coopera-tes with the seat 12 and is
~ormed on the end of a valve rod 6 which extends freely
through the ~langed member 7 and through a solenoid
arma-ture 8 which is axially slidable wi-thin the spool 2.
A compara-tively weak spring 9 urges the valve closure
member 5, and wi-th it the valve rod 6, downwards to
bring the closure member into engagement wi-th the seat
12 and close the valve. A s-tronger spring 9a acts
between the ~langed member7 and the armature 8 to urge
the armature upwards. m e armature cooperates wlth a
los-t motion with an enlargemen-t on the upper end of the
valve rod 6, so that when the armature 8 is raised
beyond a certain level, i-t engages the upper end o~ -the
valve rod and carries the valve rod and closure member
upwards with it to the position shown in Figure 1.
The lower part of the chamber 24 incorporates a
cylindrical portion which leads back to the upstream
duct part 13, this cylindrical portion containing a
slidable equilibrium member 21, which is fitted with an
0-sealing ring 23, and has a projecting valve actuator
22. m e pressure on the downstream side of the valve,
in the chamber 24, acts both on the back of the valve
closure member 5, to urge the valve closure member to
the closed position, and also on the underside of the
equilibrium member 21, to urge the member upwards to
compensate the downward force on the valve closure
member. m e valve closure member is therefore effec-t-
ively subject only to the influence of the spring 9,unless it is positively raised by the armature 8
A clutch pedal 14 is depressed to disengage a
clutch in a transmission to driven wheels of -the
vehicleO ~epression of the clutch pedal 14 Gloses a
switch 15, the contacts of which are supported by a
pivoted lever 15a, the equilibrium position of which is
set by a spring ]9 and adjuster 20. When the switch
15 is closed, current from a battery 17 flows through
a connector 16a to close a magnetic relay switch 26,
-through which current then flows from the battery
through a connector 16 to and through the coil 3 9 and
back -through a connector 18 to earth.
In operation, when the clutch pedal 14 ïs
depressed to disengage the transmission to the vehicle
driven wheels, the coil 3 is energised and the arma-ture
8 is drawn dow~lwards, thus freeing the valve closure
member 5 and rod 6 to move downwards to close -the valve
under the action of the spring 9~ Brake fluid down-
stream o~ the valve is thus trapped and the vehicle
brakes will be operated in dependence upon the pressure
-- 5 --
of the trapped fluido If additional braking is
required, the brake pedal is depressed to allow further
fluid pressure to be transmitted, this excess pressure
being sufficient to open the valve, overcoming the
action of the spring 9, as shown in Figure 3. This
brake fluid pressure cannot be released until the
clutch pedal 14 is subsequently released, -to engage the
vehicle transmission. At -that time, as shown in
Figure 4, the switch 15, and hence -the relay switch 26
are opened, deenergising the coil 3, and allowing the
armature 8 to rise under -the action of the spring 9a.
The armature engages the valve rod 6 and draws -the rod
6 and valve closure member 5 upwards, thus opening -the
valve and allowing the leak of brake fluid pressure
from the brake cylinder, and hence release of the brakeO
~e compensatory action of -the equilibrium member 21
avoids the spring 9a having to overcome the full effect
of the brake fluid pressure trapped in the chamber 24
and acting on the back of the valve closure member 5.
This is important as the brake fluid pressure can be as
high as 150 kg/cm20 The brakes can at any time be
reapplied, irrespec-tive of the configura-tion of a valve,
upon application of further brake fluid from the source
by depression o:E the brake pedal.
.
