PARKING BRAKE ASSEMBLY HAVING QUIET APPLY

FREIN DE STATIONNEMENT A SERRAGE SILENCIEUX

English Abstract

A parking brake assembly for a vehicle has a mounting bracket, a handle assembly and a clutching mechanism. The mounting bracket has a stop. The handle assembly is pivotally mounted on the mounting bracket for rotation about a first axis. The handle is moveable between a brake applied position and a brake release position. The handle has an actuator. A cam is pivotally mounted on the handle about a second axis offset from the first axis. The cam has a cam surface which varies radially from the second axis. The cam is biased to engage the stop. A clutch spring frictionally engages the cam and is operably connected to the actuator. Movement of the actuator in response to manual manipulation responsively moves the clutch spring to decrease the frictional engagement, thereby enabling the cam to engage with the stop. In response to releasing the actuator, the clutch spring moves to increase frictional engagement with the cam thereby retaining the cam in a position to engage the stop and prop the handle in a braking position.

French Abstract

Frein de stationnement pour véhicule muni d'un support de fixation, d'une poignée et d'un mécanisme d'embrayage. Le support de fixation est muni d'un dispositif d'arrêt. La poignée est installée de manière pivotante sur le support de fixation afin que puisse s'opérer une rotation autour d'un premier axe. La poignée peut être déplacée entre la position où les freins sont appliqués et la position où les freins sont relâchés. La poignée est munie d'un vérin. Une came est fixée de façon rotative sur la poignée selon un deuxième axe en retrait du premier. La came présente une surface qui varie de façon radiale par rapport au deuxième axe. La came est inclinée de manière à engager le dispositif d'arrêt. Le ressort d'embrayage engage la came par friction et est relié de façon fonctionnelle au vérin. Le mouvement du vérin en réponse au déplacement manuel fait déplacer de manière réceptive le ressort d'embrayage de façon à réduire l'engagement par friction, permettant ainsi à la came d'être engagée avec le dispositif d'arrêt. Si le vérin est relâché, le ressort d'embrayage se déplace de manière à accroître l'engagement par friction avec la came, retenant celle-ci dans une position permettant d'engager l'arrêt et de replacer la poignée en position de freinage.

Claims

I claim:
1. A parking brake for a vehicle comprising:
a mounting bracket having a stop;
a handle assembly pivotally mounted on said mounting bracket for rotation
about a first axis between a brake release position to a brake applied
position;
a cam pivotally mounted on said handle about a second axis offset from said
first axis, said cam biased to engage said stop;
an actuator operably connected to a clutch, said clutch frictionally engaging
said cam for selectively retaining said cam relative to said handle;
wherein movement of said actuator responsively moves said clutch to release
the cam enabling said cam to move relative to the handle, and in response to
releasing
said actuator, said clutch retains said cam relative to said handle to prop
said handle in
a position between the brake release position and the brake applied position.
2. A parking brake as claimed in claim 1 wherein said cam has a cam surface
having a varying radial extent from said second axis.
3. A parking brake as claimed in claim 2 wherein said clutch is a coil spring
engaging said cam.
4. A parking brake as claimed in claim 3 wherein said cam includes a pivot pin
and said coil spring is wound about said pivot pin.
5. A parking brake as claimed in claim 2 wherein said cam surface is a spiral
shape.
6. A parking brake as claimed in claim 2 wherein said cam surface is an
Archimedes spiral.
7. A parking brake as claimed in claim 1 wherein said handle has a pivot pin
for
pivotally mounting the handle to the mounting bracket and said actuator is
slidably
mounted in an end of the handle remote from said pivot pin.
8. A parking brake as claimed in claim 7 wherein said clutch is a coil spring
engaging said cam and said actuator further comprises a rod engaging said coil
spring.
9. A parking brake as claimed in claim 8 wherein said actuator is a button.
10. A parking brake as claimed in claim 9 wherein said cam has a cam surface
having a varying radial extent from said second axis.
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11. A parking brake as claimed in claim 10 wherein said cam includes a pivot
pin
and said coil spring is wound about said pivot pin.
12. A parking brake as claimed in claim 11 wherein said cam surface is a
spiral
shape.
13. A parking brake as claimed in claim 11 wherein said cam surface is an
Archimedes spiral.
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Description

CA 02324030 2000-10-19
PARKING BRAKE ASSEMBLY HAVING QUIET APPLY
Field of the Invention
The present invention relates to parking brakes for vehicles. In particular,
this
invention relates to parking brakes having quiet apply.
Background of the Invention
Conventional parking brakes have a ratchet and pawl arrangement for securing
a parking brake in a locked position. The parking brake handle can be lifted
towards the
locked position, however it cannot be lowered without disengaging the ratchet
and the
pawl. A primary disadvantage of conventional brakes is that when the parking
brake
handle is lifted, the pawl is dragged across the teeth of the ratchet. This
action creates
a loud noise, which is in some cases undesirable.
In order to remove this noise, quiet apply parking brakes have been
introduced.
The quiet apply systems that are currently available tend to be complex and
thus
expensive to make and assemble. Therefore, it is desirable to have a quiet
apply parking
brake that is simple and effective.
Summary of the Invention
The disadvantage of the prior art may be overcome by providing a parking
brake assembly for a vehicle having a quiet apply.
According to one aspect of the invention, there is provided a parking brake
for
a vehicle. The parking brake has a mounting bracket having a stop. A handle
assembly is pivotally mounted on the mounting bracket for rotation about a
first axis
between a brake release position to a brake applied position. A cam is
pivotally
mounted on the handle about a second axis offset from the first axis. The cam
is
biased to engage the stop. An actuator is operably connected to a clutch and
the
clutch frictionally engages the cam for selectively retaining the cam relative
to the
handle. Movement of the actuator responsively moves the clutch to release the
cam
enabling the cam to move relative to the handle. In response to releasing the
actuator,
the clutch retains the cam relative to the handle to prop the handle in a
position
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CA 02324030 2000-10-19
between the brake release position and the brake applied position.
According to another aspect of the invention, there is provided a parking
brake
having a mounting bracket, a handle assembly and a locking mechanism. The
mounting bracket has a stop. The handle assembly is pivotally mounted on the
mounting bracket for rotation about a first axis. The handle is moveable
between a
brake applied position and a brake release position. The handle has an
actuator. The
locking mechanism has a cam pivotally mounted on the handle about a second
axis
offset from the first axis. The cam has a cam surface which varies radially
from the
second axis. The cam is biased to engage the stop. A clutch spring
frictionally
engages the cam and is operably connected to the actuator. Movement of the
actuator
in response to manual manipulation in a first direction responsively moves the
clutch
spring to decrease the frictional engagement, thereby enabling the cam to
engage with
the stop. In response to releasing the actuator, the clutch spring moves to
increase
frictional engagement with the cam thereby retaining the cam in a position to
engage
the stop.
Brief Description of the Drawings
Figure 1 is a perspective view of the parking brake assembly of the present
invention in an unlocked position;
Figure 2 is a side elevational view of the parking brake assembly of Figure 1
in an unlocked position;
Figure 3 is a side elevational view of the parking brake assembly of Figure 1
in a brake applied position;
Figure 4 is a side elevational view of the parking brake assembly of Figure 1
in a locked position;
Figure 5 is a partial exploded perspective view of the locking assembly of the
parking brake assembly of Figure 1;
Figure 6 is a schematic diagram representing the motion of the locking cam of
the parking brake assembly of Figure 1.
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CA 02324030 2000-10-19
Detailed Description of a Preferred Embodiment
Referring to Figure 1, a parking brake assembly 10 of the present invention is
shown. The parking brake assembly 10 generally comprises a handle assembly 12,
a
mounting bracket 14 and a locking mechanism 11.
The mounting bracket 14 is a U-channel member having a longitudinal extent
having upwardly extending walls 42 and 44. Cylindrical shaft 16 extends
through
apertures 24 in walls 42 and 44. An arm 19 extends coplanar with of walls 42,
44 and
is offset longitudinally from shaft 16. Arm 19 supports a stop 18 that extends
at least
partly between the walls 42, 44 and is generally perpendicular to the walls
42, 44.
Mounting bracket 14 is configured to attach to a vehicle (not shown) in any
conventional manner.
Referring to Figure 2, handle assembly 12 comprises an elongate arm 13 with
a grip 20. Handle assembly 12 is pivotally mounted on shaft 16 at one end
region
thereof. Shaft 16 defines a first axis of rotation and allows the arm 13 to
rotate
between a brake release position (Figure 2) and a brake applied position
(Figures 3
and 4). Arm 13 is typically made of stamped metal and has an inverted U-
channel at
the base portion. Handle assembly 12 has a biased button 36 slidably mounted
in the
distal end of arm 13 remote from the shaft 16.
Locking or clutching mechanism 11 generally comprises a pivot pin 22, a rod
35, a clutch spring 30, a second spring 32 and a cam 34. Pivot pin 22 extends
through
apertures 46 in arm 13 so that pin 22 is spaced from shaft 16, defining a
second axis
of rotation. A cam 34 is fixedly mounted on the pivot pin 22.
Rod 35 extends between the actuator or button 36 and clutch spring 30 to
transmit movement of button 36 to the locking mechanism 11.
Cam 34 has a cam surface 37 on the peripheral extent thereof. The outline of
the cam surface 37 has a varying radial extent from the second axis of
rotation,
preferable shape of an Archimedes spiral as shown in Figure 6. The cam 34 has
an
arcuate cable guide (not illustrated).
Referring to Figure 5, the clutch spring 30 has a coiled section 39
terminating
in a tanged end 41 and a tai143. Coiled section 39 surrounds pivot pin 22.
Tanged
end engages arm 13 at aperture 50. The tai143 extends outwardly to
interconnect with
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CA 02324030 2000-10-19
rod 35. The coiled section 39 has an inner diameter which approximates the
diameter
of pin 22. In a relaxed condition, the coiled section 39 will frictionally
engage the pin
22 sufficiently to hold the pivot pin 22 in place. When the tail 43 is moved
in an
unwinding sense relative to the coiled section 39, the coiled section 39
expands
releasing the frictional engagement between the coiled section 39 and the
pivot pin
22.
Second spring 32 extends between pivot pin 22 at aperture 23 and the arm 13
at aperture 52. Spring 32 is shaped to engage apertures 23 and 52 at opposite
ends
thereof. Spring 32 biases the cam 34 to rotate in the locking direction to
engage with
the stop 18.
Referring to Figure 4, a Bowden cable 38 wraps around the arcuate cable
guide and attaches to the arm 13 by a fastener 40. As the arm 13 is rotated in
a
braking sense from the brake release position to the brake applied position,
upward in
the Figures, the arm 13 pulls on the cable 38 to effect a braking event at the
opposite
end. As the arm is rotated in a releasing sense, opposite the braking sense,
the arm 13
releases tension on the cable 38 to release the braking event.
Now that the apparatus has been described, the mode of operation of the
device will now be described.
Referring to Figure 2, the parking brake assembly 10 is shown in the brake
released position. When the handle assembly 12 is rotated to a brake applied
position
without pressing button 36, the cable 38 is pulled and the brake of the
vehicle is
activated in a manner well known in the art. However since the locking
mechanism 11
has not been released, the cam 34 will not rotate to engage stop 18. As a
result, the
handle assembly 12 will be free to counter rotate back to the brake release
position
under the influence of the bias of the brake rotors or calipers.
This particular mode is useful for a vehicle having a mechanical clutch. If
the
vehicle is stopped on an incline, a driver merely lifts on the handle 13 which
engages
the brakes. The driver is able to move the right foot from the brake pedal to
the
accelerator pedal without rolling backwards. Once the clutch is released to
start
engaging, the driver releases the handle 13 which immediately retracts to the
brake
release position, disengaging the brakes allowing the vehicle to proceed up
the
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CA 02324030 2000-10-19
incline.
Referring to Figure 4, once the button 36 is pressed in response to manual
manipulation, rod 35 transmits this movement to the clutch spring 30. The
clutch
spring 30 responsively rotates in an unwinding sense, releasing the frictional
engagement on pivot pin 22 allowing the cam 34 to rotate under the influence
of
spring 32. Cam 34 rotates in a locking direction into engagement with the stop
18.
Once the button 36 is released, the clutch spring 30 counter rotates in a
winding sense
to re-establish the frictional or gripping engagement with pivot pin 22. Once
the
handle assembly 12 is released, the engagement of the cam 34 with the stop 18
will
support or prop the handle 13 which will remain in the rotated or brake
applied
position maintaining tension on cable 38 and thus maintaining the braking
condition.
To unlock the handle assembly 12, button 36 is pressed and held while the
handle assembly 12 is counter rotated from the brake applied position to the
brake
release position. Pressing button 36 actuates rod 35 which rotates the clutch
spring 30
in an unwinding sense so that the clutch spring 30 releases its grip on pivot
pin 22.
As the arm 13 is counter rotated, the engagement with the stop 18 will urge
the cam
34 to return to its original position. The bias of second spring 32 is easily
overcome
by either the driver or the bias of the brake drums or calipers. Once the
handle
assembly is fully rotated to the brake release position, the button 36 is
released, re-
establishing the frictional engagement between the clutch spring 30 and the
cam 34.
Parking brakes of this type may be used on any type of vehicle. This would
include golf carts and the like and any other type of vehicle that would
benefit from
having a parking brake.
Although the invention has been described with reference to certain specific
embodiments, various modifications thereof will be apparent to those skilled
in the art
without departing from the scope of the invention as outlined in the claims
appended
hereto.
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Representative Drawing