CA2289812A1 - Friction plate return mechanism - Google Patents
Friction plate return mechanism Download PDFInfo
- Publication number
- CA2289812A1 CA2289812A1 CA 2289812 CA2289812A CA2289812A1 CA 2289812 A1 CA2289812 A1 CA 2289812A1 CA 2289812 CA2289812 CA 2289812 CA 2289812 A CA2289812 A CA 2289812A CA 2289812 A1 CA2289812 A1 CA 2289812A1
- Authority
- CA
- Canada
- Prior art keywords
- brake plate
- pin
- brake
- moving member
- moving
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 230000007246 mechanism Effects 0.000 title claims abstract description 19
- 230000009471 action Effects 0.000 claims abstract description 12
- 239000012530 fluid Substances 0.000 description 7
- 238000005096 rolling process Methods 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D65/00—Parts or details
- F16D65/38—Slack adjusters
- F16D65/40—Slack adjusters mechanical
- F16D65/52—Slack adjusters mechanical self-acting in one direction for adjusting excessive play
- F16D65/54—Slack adjusters mechanical self-acting in one direction for adjusting excessive play by means of direct linear adjustment
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D55/00—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes
- F16D55/24—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes with a plurality of axially-movable discs, lamellae, or pads, pressed from one side towards an axially-located member
- F16D55/26—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes with a plurality of axially-movable discs, lamellae, or pads, pressed from one side towards an axially-located member without self-tightening action
- F16D55/28—Brakes with only one rotating disc
- F16D55/32—Brakes with only one rotating disc actuated by a fluid-pressure device arranged in or on the brake
- F16D55/34—Brakes with only one rotating disc actuated by a fluid-pressure device arranged in or on the brake comprising an expansible fluid-filled flexible member coaxial with the brake
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D55/00—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes
- F16D2055/0004—Parts or details of disc brakes
- F16D2055/0058—Fully lined, i.e. braking surface extending over the entire disc circumference
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D2121/00—Type of actuator operation force
- F16D2121/02—Fluid pressure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D2121/00—Type of actuator operation force
- F16D2121/14—Mechanical
- F16D2121/16—Mechanical for releasing a normally applied brake
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Braking Arrangements (AREA)
Abstract
A friction plate return mechanism is provided for disengaging a brake plate from frictional contact with a rotor disk in a brake assembly for vehicles. The mechanism includes a pin slidably received in a casing that is mounted to the vehicle. The pin is biased by a spring to a rear position and is fractionally connected using a retaining washer to the brake plate to move the brake plate in a rearward direction away from the rotor disk when a braking force is removed from the plate.
Another retaining washer is received within the casing and axially movable in a predetermined distance. This retaining washer is also fractionally connected to the pin for permitting the pin freely moving in the forward direction with the brake plate during a braking action, but stopping the pin in a rearward movement together with the brake plate except moving together with the retaining washer over the predetermined distance. The advantages of the mechanism include a constant returning force and a constant travel distance of the brake plate regardless of the wearing of the contact surfaces between the brake plate and the rotor disk during the lifetime of the brake assembly.
Another retaining washer is received within the casing and axially movable in a predetermined distance. This retaining washer is also fractionally connected to the pin for permitting the pin freely moving in the forward direction with the brake plate during a braking action, but stopping the pin in a rearward movement together with the brake plate except moving together with the retaining washer over the predetermined distance. The advantages of the mechanism include a constant returning force and a constant travel distance of the brake plate regardless of the wearing of the contact surfaces between the brake plate and the rotor disk during the lifetime of the brake assembly.
Description
FRICTION PLATE RETURN MECHANISM
TECHNICAL FIELD
The present invention relates to a disk brake for vehicles and more particularly to improvements in friction plate return mechanisms for disengaging brake plate from frictional contact with a rotor disk in the disk brake assembly.
BACKGROUND ART
The friction plate return mechanism of the present invention is used in disk brakes for vehicles of the type described in the applicant's PCT patent application PCT/CA97/01014, entitled IMPROVED DISK BRAKE ASSEMBLY and published as W098/29671 in the inventor's name, Bancourt, on July 9, 1998.
The disk brake assembly for a vehicle as described in the applicant's PCT publication W098/29671 generally includes a housing mounted to the vehicle, an annular rotor disk within the housing, and means mounting the disk to the wheel. The disk has at least a first radial planar annular friction surface and the housing includes a first annular brake plate provided adjacent the first friction surface of the disk. The brake plate is axially movable towards and away from the first friction surface and is restrained from rotating with the disk. An annular fluid expandable bladder extends between the first annular brake plate and a radial wall of the housing, so that upon expansion of the bladder the first brake plate moves axially to fractionally engage the first friction surface of the disk. There are provided means for disengaging the first brake plate from frictional contact with the first friction surface of the rotor disk, which is a rolling seal provided between an axially generated surface of the brake plate and an axially generated cylindrical surface of the first radial wall of the housing such that the rolling seal can store energy when force is being applied on the brake plate to fractionally engage the frictional surface of the rotor disk, and the stored energy is sufficient to retract the brake plate from the first friction surface of the rotor disk when the applied force is removed from the brake plate.
The disk brake works well. Improvements regarding the disengaging means, however, are desired because adjustment has to be done to compensate for the increasing of the travel distance of the brake plate during a break action. The increasing of the travel distance is a result of the wearing of the friction surface of the disk. When the travel distance of the brake plate increases, the rolling seal is more resiliently deformed to store more energy so that more braking force is needed to overcome the resistance from the deformed rolling seal.
SUMMARY OF THE INVENTION
It is an aim of the present invention to provide a friction plate return mechanism for the disk brake of the type described above, which overcomes the shortcomings in the prior art.
It is another aim of the present invention to provide a friction plate return mechanism for a disk brake which is enabled to be self-adjusted to maintain a substantially constant travel distance of the brake plate regardless of the wearing of the friction surface of the rotor disk.
It is a further aim of the present invention to provide a friction plate return mechanism which is enabled to be self-adjusted to maintain a substantially constant maximum amount of energy which may be stored by the mechanism to retract the brake plate so that a braking force applied to the brake plate is kept constant regardless of the wearing of the friction surface of the rotor disk.
In accordance with one aspect of the invention, insert claim 1 (change "comprising" to "comprises") In another aspect of the invention insert claim 2 (change "comprising" to "comprises") In a specific embodiment of the present invention, a casing is provided, and both the link member and the stop member are made from a metal retaining washer. Each retaining washer includes a flat ring and a plurality of finger members extending from the flat ring inwardly and forwardly. The finger members are circumferentially positioned and the ends of the finger members define an aperture slightly smaller than the exterior of a pin which acts as the moving member. The ends of the finger members are enabled to be resiliently displaced to permit the pin to be inserted from a rear side through the retaining washer, and the finger members grip the exterior of the pin to prevent the pin from moving in a rearward direction relative to the retaining washer.
However, the pin is enabled to be moved in rearward direction relative to the retaining washer or the retaining washer is enabled to be moved in the forward direction relative to the pin when the force to move the pin or the retaining washer is greater than the friction force between the finger members and the exterior of the pin.
One of the retaining washers acting as the link member receives the pin extending therethrough and mounted to the brake plate in a manner that the front side of the retaining washer faces the rotor disk so that when the brake plate is forcibly moved towards the rotor disk, the finger members of the retaining washer grip the pin and move the pin together in the forward direction.
Once a spring in the housing and connected to the pin is compressed to a certain extent, the pin stops moving forward and is maintained in this position while the retaining washer slides on the pin when the brake plate continues moving forwards to engage the rotor disk in a brake action. The friction force between the finger members and the exterior of the pin brings the brake plate to disengage from the rotor disk when the braking force is removed and the spring force moves the pin in the rearward direction.
The other retaining washer acting as the stop member surrounds the exterior of the pin and is contained within a chamber of the housing. The periphery of the chamber is defined by a circumferentially extending groove which receives the flat ring of the retaining washer. The retaining washer is axially movable within the chamber and the axial movement is limited by the width of the groove. The retaining washer is moved together with the pin in the forward direction in a brake action until the flat ring abuts a front side of the groove, and permits the pin to slide through the retaining washer to continue the forward movement. When the braking force is removed and the pin moves in the rearward direction under the spring force, the retaining washer is moved together with the pin in the rearward direction until the flat ring abuts the rear side of the groove to stop the rearward movement of the pin. The spring force is never greater than the friction force between the finger members and the exterior of the pin and therefore, the finger members are able to grip the pin firmly and to stop the rearward movement.
The friction plate return mechanism according to the present invention presents an advantageous self-adjustment function to compensate for brake wearing so that both the traveling distance of the brake plate and the braking force applied on the brake plate are maintained constant during the service life of the disk brake assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
Having thus described the nature of the invention, the invention will now be described in detail, having reference to the accompanying drawings in which:
Figure 1 is a partial sectional view of a disk brake incorporating a preferred embodiment of the invention;
Figure 2 is an exploded perspective view of the embodiment in Figure 1;
Figure 3 is a front view of the retaining washer used in the embodiment in Figure 1; and Figure 4 is a cross-sectional view taken along line 4-4 in Figure 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, and particularly to Figure l, a friction plate return mechanism 10 is installed to a disk brake 14 for an automobile. The disk brake 14 is not a part of the invention and many different types of disk brakes may incorporate the embodiment of the invention. Therefore, the disk brake is described merely with its basic structure to illustrate the braking operation of the disk brake using the friction plate return mechanism 10. The disk brake 14 generally includes a housing 16 mounted to the automobile, an annular rotor disk 18 within the housing, and mounting member 20 for mounting the disk 18 to the wheel 22 of the automobile. The disk 18 has at least a radial planar annular frictional surface 24 and the housing includes an annular brake plate 26 provided adjacent the friction surface 18 of the disk. The brake plate 26 is movable axially towards and away from the frictional surface 24 but is restrained from rotating with the disk 18. The housing 16 includes an annular radial wall 28 parallel to the brake plate 26, and an annular fluid expandable bladder 30 with a fitting member 32 extending between the annular brake plate 26 and the _ g _ annular radial wall 28. When the brake fluid is pumped into the inside of the bladder 30, the expansion of the bladder 30 moves the brake plate 26 axially to fractionally engage the frictional surface 24 of the disk 18. The friction plate return mechanism 10 is used to move the brake plate 26 for disengaging from frictional contact with the frictional surface 24 of the rotor disk 18 upon release of the brake fluid from the bladder 30.
The friction plate return mechanism 10 includes a cylindrical casing 34 and a pin 36 which are more clearly illustrated in Figure 2. The cylindrical casing 34 is closed at the rear end 38 and has a central opening 40 at the front end 42. The pin 36 is slidably received within the casing 34 and a front portion of the pin 36 protrudes forwardly from the central opening 40. A spiral spring 44 is contained within a bigger chamber 46, and positioned between a front wall 48 of the chamber 46 and an enlarged pin head 50 such that the pin 36 is biased to a rear position in which the pin head 50 contacts the closed end 38 of the cylindrical housing. An enlarged rear portion 52 of the pin 36 prevents the pin 36 from overprotruding forwardly from the cylindrical casing when it abuts the front wall 48 of the chamber 46.
A smaller chamber 54 is defined within the cylindrical casing 34 near the front end 42, and the central opening 40 extends axially through the chamber 54.
Two retaining washers 56 and 58 are provided. The structure and size of the retaining washer 56, 58 are identical and more clearly illustrated in Figures 3 and 4. The retaining washer 56 or 58 is made from an integral metal plate having a central aperture. The metal plate includes an annular outer section forming a flat ring 60 and an annular inner portion forming a plurality of finger members 62 which are circumferentially spaced apart from one another by a plurality of radially extending cuts 64. The finger members 62 are bent in permanent deformation in one direction which is referred to as a forward direction hereinafter. The final opening 66 defined by the ends of the finger members 62 is slightly smaller than the exterior of the pin 36. The finger members 36 are enabled to be resiliently deformed slightly to permit the pin 36 to be inserted from the rear side of the retaining washer 56 therethrough.
However, if the pin 36 is to be moved in the rearward direction relative to the retaining washer 56, the friction force between the exterior of the pin 36 of the finger members 62 is in a trend to move the ends of the finger members 62 together with the pin 36 to further grip the pin 36 and stop the movement thereof. G~Then the pin 36 is moved in the rearward direction by a force greater than or equal to the maximum friction force between the exterior of the pin and the finger members, the retaining washer 56 or 58 is no longer able to stop the rearward movement of the pin 36.
The retaining washer 58 is mounted to the brake plate 26 in fixed relation and receives a front portion of the pin 36 extending therethrough as shown in Figure 1. When break fluid is pumped into the bladder 30 and the disk plate 26 is moved towards the frictional surface 24 of the rotor disk 18, the retaining washer 58 grips the pin 36 to move together with the disk plate 26 in the forward direction against the spring force applied on the pin head 50. After the break action is completed and the brake fluid is released from the bladder 30, the spring force acting on the pin head 50 moves the disk plate 26 rearwardly for disengaging from frictional contact with the frictional surface 24. As the frictional surface 24 wears out, the disk plate 26 has to travel a longer distance from its original position to engage the frictional surface 24. That means the pin 36 would have to travel together with the disk plate 26 over the longer distance and the spring 44 would be more compressed to produce greater spring forces acting on the pin head 50 if the pin 36 was connected to the disk plate 26 in a fixed relation. However, the connection between the retaining washer 58 and the pin 36 is not in a fixed relation. When the pin 36 moves together with the disk plate 26 in the forward direction over a certain distance, and the spring force acting on the pin head 50 is equal to the maximum friction force between the retaining washer 58 and the pin 36, the pin 36 stops moving further while the retaining washer 58 slides on the pin 36 and continues moving together with the disk plate 26 in the forward direction until the disk plate 26 engages the frictional surface 24 of the rotor disk 18.
Practically, the spring forces acting on the pin head 50 will never be greater than the maximum friction force between the retaining washer 58 and the pin 36 and therefore, the spring force is able to move the pin 36 together with the disk plate 26 in the rearward direction for the disengagement. In such a situation, the maximum resistant force which the brake disk 26 has to overcome in a braking action is constant regardless of the wearing of the frictional surface 24 during a lifetime of the brake assembly. The maximum resistant force is equal to the maximum friction force between the retaining washer 58 and the exterior of the pin 36, and therefore, it can be predetermined and achieved by requirements in the designs of the pin 36 and the retaining washer 58.
The retaining washer 56 is mounted on the pin 36 and received in the chamber 54 of the cylindrical casing 34.
The periphery of the chamber 54 is defined by a circumferentially extending groove 68 for receiving the flat ring 60 of the retaining washer 56 and permitting the retaining washer 56 to be axially movable within a range of the width of the groove 68. The retaining washer 56 acts as a self-adjustable stop member, limiting the travel distance of the brake plate 26 during a braking action while compensating for the position change of the frictional surface 24 caused by the wearing over a period of time of performance. When the pin 36 is moved by the disk plate 26 in the forward braking action, the retaining washer 56 is freely moved together with the pin 36 by a little friction force existing between the pin 36 and the retaining washer 56 until the flat ring 60 of the retaining washer 56 abuts the front side of the groove 68. However, the retaining washer 56 stopped by the front side of the groove 68 does not stop the pin 36 in the forward movement and the pin 36 stops only when the spring force acting on the pin head 50 is equal to the maximum friction force between the pin 36 and the retaining washer 58, as described above. It is noted that in this stage, the friction force between the pin 36 and the retaining washer 56 is in a direction opposite to the direction of the friction force between the pin 36 and the retaining washer 58 because the retaining washer 58 is a driving member in the forward movement of the pin 36 while the retaining washer 68 is a driven member. It is also noted that in this movement mode the maximum friction force related to the retaining washer 56 is much smaller than the maximum friction force related to the washer 58, and therefore, the relative movement between the pin 36 and the retaining washer 56 occurs earlier than the relative movement between the pin 36 and the retaining washer 58.
When the braking action is completed and the brake fluid is released from the bladder 30, the disk plate 26 is pulled away from the frictional surface 24 of the disk 18 by the pin 36 under the spring force. Both the retaining washers 56, 58 are the driven members in the rearward movement of the pin 36, and both friction forces acting on the retaining washers 56, 58 are in the same direction. The spring force is equal to the maximum friction force related to the respective retaining washers 56, 58 and gradually reduces as the pin 36 and the brake plate move in the rearward direction. The brake plate 26 is moved away from the frictional surface 24 only over a short distance determined by the width of the groove 68 because when the retaining washer 56 abuts the rear side of the groove 68 during its rearward movement together with the pin 36, the friction force between the pin 36 and the retaining washer 56 stops the pin 36 and the disk plate 26. The reason as discussed above with respect to the retaining washer 58, is that the spring force acting on the pin head 50 is not enough to overcome the maximum friction force between the pin 36 and the retaining washer 56 to make the pin 36 slide through the retaining washer 56 in the rearward movement.
The above described embodiment is an example for illustration of the principal of the invention. Any types of the link member which is enabled to be fractionally connected with the pin 36 can be used to replace the retaining washer 58, such as a rubber ring associated in a fixed relation with the disk plate 26 and surrounding the pin 36 in frictional contact. Any types of stop member able to be fractionally connected to the pin 36 may be used to replace the retaining washer 56. However, the frictional features of the stop member in opposite directions must be different so that the maximum friction force in one direction is much smaller than the friction force in the opposite direction to permit the pin 36 to slide through the stop member with little resistance while the maximum friction force in the opposite direction is sufficient to overcome the spring force acting on the pin 36 to stop the pin 36 in its rearward movement. It is noted that the maximum friction force between the pin 36 and the stop member in the rearward movement of the pin 36 must be not smaller than the maximum friction force between the pin and the link member to ensure the spring force acting on the pin is never greater than the maximum friction force between the pin and the stop member.
Other modifications or changes without departing from the principal of the present invention will be obvious to those skilled in the art. The embodiment described above is exemplary and not intended to limit the scope of the invention which will be solely defined and limited by the appended claims.
TECHNICAL FIELD
The present invention relates to a disk brake for vehicles and more particularly to improvements in friction plate return mechanisms for disengaging brake plate from frictional contact with a rotor disk in the disk brake assembly.
BACKGROUND ART
The friction plate return mechanism of the present invention is used in disk brakes for vehicles of the type described in the applicant's PCT patent application PCT/CA97/01014, entitled IMPROVED DISK BRAKE ASSEMBLY and published as W098/29671 in the inventor's name, Bancourt, on July 9, 1998.
The disk brake assembly for a vehicle as described in the applicant's PCT publication W098/29671 generally includes a housing mounted to the vehicle, an annular rotor disk within the housing, and means mounting the disk to the wheel. The disk has at least a first radial planar annular friction surface and the housing includes a first annular brake plate provided adjacent the first friction surface of the disk. The brake plate is axially movable towards and away from the first friction surface and is restrained from rotating with the disk. An annular fluid expandable bladder extends between the first annular brake plate and a radial wall of the housing, so that upon expansion of the bladder the first brake plate moves axially to fractionally engage the first friction surface of the disk. There are provided means for disengaging the first brake plate from frictional contact with the first friction surface of the rotor disk, which is a rolling seal provided between an axially generated surface of the brake plate and an axially generated cylindrical surface of the first radial wall of the housing such that the rolling seal can store energy when force is being applied on the brake plate to fractionally engage the frictional surface of the rotor disk, and the stored energy is sufficient to retract the brake plate from the first friction surface of the rotor disk when the applied force is removed from the brake plate.
The disk brake works well. Improvements regarding the disengaging means, however, are desired because adjustment has to be done to compensate for the increasing of the travel distance of the brake plate during a break action. The increasing of the travel distance is a result of the wearing of the friction surface of the disk. When the travel distance of the brake plate increases, the rolling seal is more resiliently deformed to store more energy so that more braking force is needed to overcome the resistance from the deformed rolling seal.
SUMMARY OF THE INVENTION
It is an aim of the present invention to provide a friction plate return mechanism for the disk brake of the type described above, which overcomes the shortcomings in the prior art.
It is another aim of the present invention to provide a friction plate return mechanism for a disk brake which is enabled to be self-adjusted to maintain a substantially constant travel distance of the brake plate regardless of the wearing of the friction surface of the rotor disk.
It is a further aim of the present invention to provide a friction plate return mechanism which is enabled to be self-adjusted to maintain a substantially constant maximum amount of energy which may be stored by the mechanism to retract the brake plate so that a braking force applied to the brake plate is kept constant regardless of the wearing of the friction surface of the rotor disk.
In accordance with one aspect of the invention, insert claim 1 (change "comprising" to "comprises") In another aspect of the invention insert claim 2 (change "comprising" to "comprises") In a specific embodiment of the present invention, a casing is provided, and both the link member and the stop member are made from a metal retaining washer. Each retaining washer includes a flat ring and a plurality of finger members extending from the flat ring inwardly and forwardly. The finger members are circumferentially positioned and the ends of the finger members define an aperture slightly smaller than the exterior of a pin which acts as the moving member. The ends of the finger members are enabled to be resiliently displaced to permit the pin to be inserted from a rear side through the retaining washer, and the finger members grip the exterior of the pin to prevent the pin from moving in a rearward direction relative to the retaining washer.
However, the pin is enabled to be moved in rearward direction relative to the retaining washer or the retaining washer is enabled to be moved in the forward direction relative to the pin when the force to move the pin or the retaining washer is greater than the friction force between the finger members and the exterior of the pin.
One of the retaining washers acting as the link member receives the pin extending therethrough and mounted to the brake plate in a manner that the front side of the retaining washer faces the rotor disk so that when the brake plate is forcibly moved towards the rotor disk, the finger members of the retaining washer grip the pin and move the pin together in the forward direction.
Once a spring in the housing and connected to the pin is compressed to a certain extent, the pin stops moving forward and is maintained in this position while the retaining washer slides on the pin when the brake plate continues moving forwards to engage the rotor disk in a brake action. The friction force between the finger members and the exterior of the pin brings the brake plate to disengage from the rotor disk when the braking force is removed and the spring force moves the pin in the rearward direction.
The other retaining washer acting as the stop member surrounds the exterior of the pin and is contained within a chamber of the housing. The periphery of the chamber is defined by a circumferentially extending groove which receives the flat ring of the retaining washer. The retaining washer is axially movable within the chamber and the axial movement is limited by the width of the groove. The retaining washer is moved together with the pin in the forward direction in a brake action until the flat ring abuts a front side of the groove, and permits the pin to slide through the retaining washer to continue the forward movement. When the braking force is removed and the pin moves in the rearward direction under the spring force, the retaining washer is moved together with the pin in the rearward direction until the flat ring abuts the rear side of the groove to stop the rearward movement of the pin. The spring force is never greater than the friction force between the finger members and the exterior of the pin and therefore, the finger members are able to grip the pin firmly and to stop the rearward movement.
The friction plate return mechanism according to the present invention presents an advantageous self-adjustment function to compensate for brake wearing so that both the traveling distance of the brake plate and the braking force applied on the brake plate are maintained constant during the service life of the disk brake assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
Having thus described the nature of the invention, the invention will now be described in detail, having reference to the accompanying drawings in which:
Figure 1 is a partial sectional view of a disk brake incorporating a preferred embodiment of the invention;
Figure 2 is an exploded perspective view of the embodiment in Figure 1;
Figure 3 is a front view of the retaining washer used in the embodiment in Figure 1; and Figure 4 is a cross-sectional view taken along line 4-4 in Figure 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, and particularly to Figure l, a friction plate return mechanism 10 is installed to a disk brake 14 for an automobile. The disk brake 14 is not a part of the invention and many different types of disk brakes may incorporate the embodiment of the invention. Therefore, the disk brake is described merely with its basic structure to illustrate the braking operation of the disk brake using the friction plate return mechanism 10. The disk brake 14 generally includes a housing 16 mounted to the automobile, an annular rotor disk 18 within the housing, and mounting member 20 for mounting the disk 18 to the wheel 22 of the automobile. The disk 18 has at least a radial planar annular frictional surface 24 and the housing includes an annular brake plate 26 provided adjacent the friction surface 18 of the disk. The brake plate 26 is movable axially towards and away from the frictional surface 24 but is restrained from rotating with the disk 18. The housing 16 includes an annular radial wall 28 parallel to the brake plate 26, and an annular fluid expandable bladder 30 with a fitting member 32 extending between the annular brake plate 26 and the _ g _ annular radial wall 28. When the brake fluid is pumped into the inside of the bladder 30, the expansion of the bladder 30 moves the brake plate 26 axially to fractionally engage the frictional surface 24 of the disk 18. The friction plate return mechanism 10 is used to move the brake plate 26 for disengaging from frictional contact with the frictional surface 24 of the rotor disk 18 upon release of the brake fluid from the bladder 30.
The friction plate return mechanism 10 includes a cylindrical casing 34 and a pin 36 which are more clearly illustrated in Figure 2. The cylindrical casing 34 is closed at the rear end 38 and has a central opening 40 at the front end 42. The pin 36 is slidably received within the casing 34 and a front portion of the pin 36 protrudes forwardly from the central opening 40. A spiral spring 44 is contained within a bigger chamber 46, and positioned between a front wall 48 of the chamber 46 and an enlarged pin head 50 such that the pin 36 is biased to a rear position in which the pin head 50 contacts the closed end 38 of the cylindrical housing. An enlarged rear portion 52 of the pin 36 prevents the pin 36 from overprotruding forwardly from the cylindrical casing when it abuts the front wall 48 of the chamber 46.
A smaller chamber 54 is defined within the cylindrical casing 34 near the front end 42, and the central opening 40 extends axially through the chamber 54.
Two retaining washers 56 and 58 are provided. The structure and size of the retaining washer 56, 58 are identical and more clearly illustrated in Figures 3 and 4. The retaining washer 56 or 58 is made from an integral metal plate having a central aperture. The metal plate includes an annular outer section forming a flat ring 60 and an annular inner portion forming a plurality of finger members 62 which are circumferentially spaced apart from one another by a plurality of radially extending cuts 64. The finger members 62 are bent in permanent deformation in one direction which is referred to as a forward direction hereinafter. The final opening 66 defined by the ends of the finger members 62 is slightly smaller than the exterior of the pin 36. The finger members 36 are enabled to be resiliently deformed slightly to permit the pin 36 to be inserted from the rear side of the retaining washer 56 therethrough.
However, if the pin 36 is to be moved in the rearward direction relative to the retaining washer 56, the friction force between the exterior of the pin 36 of the finger members 62 is in a trend to move the ends of the finger members 62 together with the pin 36 to further grip the pin 36 and stop the movement thereof. G~Then the pin 36 is moved in the rearward direction by a force greater than or equal to the maximum friction force between the exterior of the pin and the finger members, the retaining washer 56 or 58 is no longer able to stop the rearward movement of the pin 36.
The retaining washer 58 is mounted to the brake plate 26 in fixed relation and receives a front portion of the pin 36 extending therethrough as shown in Figure 1. When break fluid is pumped into the bladder 30 and the disk plate 26 is moved towards the frictional surface 24 of the rotor disk 18, the retaining washer 58 grips the pin 36 to move together with the disk plate 26 in the forward direction against the spring force applied on the pin head 50. After the break action is completed and the brake fluid is released from the bladder 30, the spring force acting on the pin head 50 moves the disk plate 26 rearwardly for disengaging from frictional contact with the frictional surface 24. As the frictional surface 24 wears out, the disk plate 26 has to travel a longer distance from its original position to engage the frictional surface 24. That means the pin 36 would have to travel together with the disk plate 26 over the longer distance and the spring 44 would be more compressed to produce greater spring forces acting on the pin head 50 if the pin 36 was connected to the disk plate 26 in a fixed relation. However, the connection between the retaining washer 58 and the pin 36 is not in a fixed relation. When the pin 36 moves together with the disk plate 26 in the forward direction over a certain distance, and the spring force acting on the pin head 50 is equal to the maximum friction force between the retaining washer 58 and the pin 36, the pin 36 stops moving further while the retaining washer 58 slides on the pin 36 and continues moving together with the disk plate 26 in the forward direction until the disk plate 26 engages the frictional surface 24 of the rotor disk 18.
Practically, the spring forces acting on the pin head 50 will never be greater than the maximum friction force between the retaining washer 58 and the pin 36 and therefore, the spring force is able to move the pin 36 together with the disk plate 26 in the rearward direction for the disengagement. In such a situation, the maximum resistant force which the brake disk 26 has to overcome in a braking action is constant regardless of the wearing of the frictional surface 24 during a lifetime of the brake assembly. The maximum resistant force is equal to the maximum friction force between the retaining washer 58 and the exterior of the pin 36, and therefore, it can be predetermined and achieved by requirements in the designs of the pin 36 and the retaining washer 58.
The retaining washer 56 is mounted on the pin 36 and received in the chamber 54 of the cylindrical casing 34.
The periphery of the chamber 54 is defined by a circumferentially extending groove 68 for receiving the flat ring 60 of the retaining washer 56 and permitting the retaining washer 56 to be axially movable within a range of the width of the groove 68. The retaining washer 56 acts as a self-adjustable stop member, limiting the travel distance of the brake plate 26 during a braking action while compensating for the position change of the frictional surface 24 caused by the wearing over a period of time of performance. When the pin 36 is moved by the disk plate 26 in the forward braking action, the retaining washer 56 is freely moved together with the pin 36 by a little friction force existing between the pin 36 and the retaining washer 56 until the flat ring 60 of the retaining washer 56 abuts the front side of the groove 68. However, the retaining washer 56 stopped by the front side of the groove 68 does not stop the pin 36 in the forward movement and the pin 36 stops only when the spring force acting on the pin head 50 is equal to the maximum friction force between the pin 36 and the retaining washer 58, as described above. It is noted that in this stage, the friction force between the pin 36 and the retaining washer 56 is in a direction opposite to the direction of the friction force between the pin 36 and the retaining washer 58 because the retaining washer 58 is a driving member in the forward movement of the pin 36 while the retaining washer 68 is a driven member. It is also noted that in this movement mode the maximum friction force related to the retaining washer 56 is much smaller than the maximum friction force related to the washer 58, and therefore, the relative movement between the pin 36 and the retaining washer 56 occurs earlier than the relative movement between the pin 36 and the retaining washer 58.
When the braking action is completed and the brake fluid is released from the bladder 30, the disk plate 26 is pulled away from the frictional surface 24 of the disk 18 by the pin 36 under the spring force. Both the retaining washers 56, 58 are the driven members in the rearward movement of the pin 36, and both friction forces acting on the retaining washers 56, 58 are in the same direction. The spring force is equal to the maximum friction force related to the respective retaining washers 56, 58 and gradually reduces as the pin 36 and the brake plate move in the rearward direction. The brake plate 26 is moved away from the frictional surface 24 only over a short distance determined by the width of the groove 68 because when the retaining washer 56 abuts the rear side of the groove 68 during its rearward movement together with the pin 36, the friction force between the pin 36 and the retaining washer 56 stops the pin 36 and the disk plate 26. The reason as discussed above with respect to the retaining washer 58, is that the spring force acting on the pin head 50 is not enough to overcome the maximum friction force between the pin 36 and the retaining washer 56 to make the pin 36 slide through the retaining washer 56 in the rearward movement.
The above described embodiment is an example for illustration of the principal of the invention. Any types of the link member which is enabled to be fractionally connected with the pin 36 can be used to replace the retaining washer 58, such as a rubber ring associated in a fixed relation with the disk plate 26 and surrounding the pin 36 in frictional contact. Any types of stop member able to be fractionally connected to the pin 36 may be used to replace the retaining washer 56. However, the frictional features of the stop member in opposite directions must be different so that the maximum friction force in one direction is much smaller than the friction force in the opposite direction to permit the pin 36 to slide through the stop member with little resistance while the maximum friction force in the opposite direction is sufficient to overcome the spring force acting on the pin 36 to stop the pin 36 in its rearward movement. It is noted that the maximum friction force between the pin 36 and the stop member in the rearward movement of the pin 36 must be not smaller than the maximum friction force between the pin and the link member to ensure the spring force acting on the pin is never greater than the maximum friction force between the pin and the stop member.
Other modifications or changes without departing from the principal of the present invention will be obvious to those skilled in the art. The embodiment described above is exemplary and not intended to limit the scope of the invention which will be solely defined and limited by the appended claims.
Claims (3)
1. A mechanism for disengaging a brake plate from frictional contact with a rotor disk in a brake assembly for vehicles comprising:
a moving member associated with the vehicle and slidable relative to the vehicle in a forward and a rearward direction of movements of the brake plate;
resilient means associated with the moving member for forcing the moving member moving towards a rearward position;
a friction link member in a fixed relation with the brake plate and fractionally connected with the moving member to move the moving member together with the brake plate in the forward movement towards the rotor disk during a braking action until a resistant force caused from the resilient means is equal to a predetermined maximum friction force between the moving member and the link member, the friction link member moving the brake plate together with the moving member in the rearward direction when a braking force is removed from the brake plate.
a moving member associated with the vehicle and slidable relative to the vehicle in a forward and a rearward direction of movements of the brake plate;
resilient means associated with the moving member for forcing the moving member moving towards a rearward position;
a friction link member in a fixed relation with the brake plate and fractionally connected with the moving member to move the moving member together with the brake plate in the forward movement towards the rotor disk during a braking action until a resistant force caused from the resilient means is equal to a predetermined maximum friction force between the moving member and the link member, the friction link member moving the brake plate together with the moving member in the rearward direction when a braking force is removed from the brake plate.
2. A mechanism for disengaging a brake plate from frictional contact with a rotor disk in a brake assembly for vehicles comprising:
a moving member associated with the vehicle and slidable relative to the vehicle in a forward and a rearward direction of movement of the brake plate;
resilient means associated with the moving member for forcing the moving member moving towards a rearward position;
a link member to connect the brake plate and the moving member; and a stop member associated with the vehicle and slidable relative to the vehicle in the forward and rearward direction within a predetermined distance; the stop member being fractionally connected to the moving member, a maximum friction force in one direction between the moving member and the stop member permitting the moving member to move together with the brake plate in the forward direction during a brake action with a little resistance from the stop member when the stop member is restrained, while a maximum friction force in the opposite direction between the moving member and the stop member prevents the moving member from moving in the rearward direction relative to the stop member so that the brake plate and the moving member are only enabled to move away from the rotor disk in the rearward direction together with the stop member within the predetermined distance when a brake force is removed from the brake plate.
a moving member associated with the vehicle and slidable relative to the vehicle in a forward and a rearward direction of movement of the brake plate;
resilient means associated with the moving member for forcing the moving member moving towards a rearward position;
a link member to connect the brake plate and the moving member; and a stop member associated with the vehicle and slidable relative to the vehicle in the forward and rearward direction within a predetermined distance; the stop member being fractionally connected to the moving member, a maximum friction force in one direction between the moving member and the stop member permitting the moving member to move together with the brake plate in the forward direction during a brake action with a little resistance from the stop member when the stop member is restrained, while a maximum friction force in the opposite direction between the moving member and the stop member prevents the moving member from moving in the rearward direction relative to the stop member so that the brake plate and the moving member are only enabled to move away from the rotor disk in the rearward direction together with the stop member within the predetermined distance when a brake force is removed from the brake plate.
3. A mechanism as claimed in claim 2 wherein the link member is associated in a fixed relation with the brake plate and fractionally connected with the moving member to move the moving member together with the brake plate in the forward movement towards the rotor disk during the braking action until a resistant force caused from the resilient means is equal to a predetermined maximum friction force between the moving member and the link member, the link member moving the brake plate together with the moving member in the rearward direction with the predetermined distance permitted by the stop member when brake force is removed from the brake plate.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2289812 CA2289812A1 (en) | 1999-11-15 | 1999-11-15 | Friction plate return mechanism |
| CA002427951A CA2427951A1 (en) | 1999-11-15 | 2000-11-15 | Friction plate return mechanism |
| PCT/CA2000/001362 WO2001036838A1 (en) | 1999-11-15 | 2000-11-15 | Friction plate return mechanism |
| AU16830/01A AU1683001A (en) | 1999-11-15 | 2000-11-15 | Friction plate return mechanism |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2289812 CA2289812A1 (en) | 1999-11-15 | 1999-11-15 | Friction plate return mechanism |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2289812A1 true CA2289812A1 (en) | 2001-05-15 |
Family
ID=4164620
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2289812 Abandoned CA2289812A1 (en) | 1999-11-15 | 1999-11-15 | Friction plate return mechanism |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU1683001A (en) |
| CA (1) | CA2289812A1 (en) |
| WO (1) | WO2001036838A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102007001213B4 (en) * | 2007-01-05 | 2008-09-04 | Knorr-Bremse Systeme für Nutzfahrzeuge GmbH | Disc brake, in particular for a commercial vehicle |
| DE102012006111A1 (en) | 2012-03-26 | 2013-09-26 | Knorr-Bremse Systeme für Nutzfahrzeuge GmbH | Disc brake, in particular for a commercial vehicle |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1207766A (en) * | 1957-07-10 | 1960-02-18 | Dunlop Sa | Adjustment device by infinitely small increments and brake fitted with such a device |
| US3815716A (en) * | 1973-03-19 | 1974-06-11 | Gen Motors Corp | Automatic piston adjuster |
| US4382491A (en) * | 1980-08-11 | 1983-05-10 | Hurst Performance, Inc. | Drag free disc brake assembly having automatically adjusting caliper |
| DE4031335A1 (en) * | 1990-10-04 | 1992-04-09 | Knorr Bremse Ag | DISC BRAKE, ESPECIALLY DISC DISC BRAKE FOR RAIL VEHICLES |
| US5465816A (en) * | 1994-07-20 | 1995-11-14 | Westinghouse Air Brake Company | Slack adjusting brake cylinder for a brake unit on a railway transit vehicle |
| BR9714120A (en) | 1996-12-31 | 2000-02-29 | Yvon Rancourt Canadense Tecnic | Improving disc brake set |
| AUPO478597A0 (en) * | 1997-01-24 | 1997-02-20 | Woollams, John | Automatic adjuster for spring applied mechanisms |
-
1999
- 1999-11-15 CA CA 2289812 patent/CA2289812A1/en not_active Abandoned
-
2000
- 2000-11-15 AU AU16830/01A patent/AU1683001A/en not_active Abandoned
- 2000-11-15 WO PCT/CA2000/001362 patent/WO2001036838A1/en active Application Filing
Also Published As
| Publication number | Publication date |
|---|---|
| WO2001036838A1 (en) | 2001-05-25 |
| AU1683001A (en) | 2001-05-30 |
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| Date | Code | Title | Description |
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| FZDE | Dead |