GB2588179A

GB2588179A - Brake Assembly

Info

Publication number: GB2588179A
Application number: GB1914755.2A
Authority: GB
Inventors: Pike Russell; Zenzen Guido; Maeurer Peter; Becker Marco; Knieper Joerg; Madzgalla Lukas; Roessinger Florian; Schwenzer Philip; Wecker Paul
Original assignee: ZF Active Safety GmbH; TRW Ltd
Current assignee: ZF Active Safety GmbH; TRW Ltd
Priority date: 2019-10-11
Filing date: 2019-10-11
Publication date: 2021-04-21
Anticipated expiration: 2039-10-11
Also published as: GB201914755D0; DE102020126095A1; GB2588179B; CN112648313A

Abstract

A brake pad sub-assembly comprises a bracket (102, fig 2) having a channel (110) and at least one brake pad (104) supported by the bracket (102) and configured to slide along the channel (110) in response to an application force in an engagement direction. The brake pad (104) includes an end portion (114) configured to be seated within the channel (110) and upon which a resilient block 118 is mounted. The resilient block 118 includes a bearing surface that bears upon the channel (110). The end portion (114) is seated within a recess 120 and a spring element 124 is configured to deform in response to the application force. The spring element 124 subsequently provides a recoil force in a disengagement direction opposite to the engagement direction when the application force is lowered or removed.

Description

BRAKE ASSEMBLY

The present invention relates to a brake assembly, particularly but not necessarily exclusively for a motor vehicle. The invention also relates to a brake pad subassembly.

Braking assemblies are well-known. When used in relation to motor vehicles, braking assemblies are commonly used to slow the rotation of one or more wheels of the vehicle, in order to slow the vehicle and to bring it to a halt. In modern times, the most ubiquitous of braking assemblies is known as a disc brake assembly, whereby brake pads are pressed by calipers onto a rotor, in order to slow the rotor and the wheel to which it is attached.

As braking systems have progressed, it has become of increasing importance to minimise noise associated with the braking assemblies. Moreover, preventing or limiting any torques acting on the braking assembly when the brake is released is also important, to ensure the best possible functioning of the braking system whilst minimising the energy consumption of the vehicle.

According to a first aspect, there is provided a brake pad sub-assembly comprising: a bracket comprising a channel; and at least one brake pad supported by the bracket and configured to slide along the channel in response to an application force in an engagement direction; wherein the brake pad includes an end portion configured to be seated within the channel and upon which a resilient block is mounted; wherein the resilient block includes a bearing surface that bears upon the channel, a recess within which the end portion is seated, and a spring element configured to deform in response to the application force, the spring element subsequently providing a recoil force in a disengagement direction opposite to the engagement direction when the application force is lowered or removed.

The resilient block provides a bearing surface that can slide along the channel during application and release of the brakes. The resilience of the block ensures that noise produced by the assembly is low. Moreover, the resilient block ensures reduced corrosion and the avoidance of a galvanic cell being produced within the assembly.

Additionally, the spring element of the resilient block provides a recoil force that ensures that release of the brakes, i.e. lowering or removing the application force, results in complete disengagement of the brake pads from a rotor with which they are being used.

The spring element may be formed unitarily with the resilient block. This simplifies the manufacture and assembly of the sub-assembly.

Deformation of the spring element in response to the application force may cause deformation of the resilient block such that there is an increase in friction between the resilient block and the channel.

Increasing the friction between the resilient block and the channel increases the resistance to movement of the resilient block down the channel. This increased resistance therefore means that increasing the application force causes increased compression of the spring element until the increased frictional force is overcome Deformation of the resilient block in response to the application force may increase a contact area between the resilient block and the channel. The increase in contact area may increase the frictional force between the resilient block and channel.

The spring element may be shaped, or may interact with the resilient block, to transform the deformation of the spring element into the deformation of the resilient block. The compression of the spring clement may therefore be transformed into expansion of the resilient block, for example to increase the contact area between the resilient block and the channel.

The spring element may be formed as a triangular protrusion within the recess of the resilient block.

The triangular protrusion may have a greater width than length.

The use of a triangular protrusion may provide the means by which the direction of the application force is transformed.

The brake pad may be configured to slide along the channel once friction between the resilient block and channel is overcome.

In this way, wear of the brake pad can be compensated by sliding of the brake pad in order to reposition the brake pad relative to a brake rotor. The sub-assembly can therefore adapt throughout its lifetime.

The spring element may be positioned such that the end portion deforms the spring element as the application force is applied.

The resilient block may further include a release element that acts to deform the resilient block to lower friction between the resilient block and the channel when a release force is applied to the brake pad in the disengagement direction.

By including a release element, the disengagement of the brake pad from a brake rotor may be made easier. This ensures that wastage of energy through unwanted contact between the brake pad and brake rotor is limited and also that circumstances where the rotor may deflect, for example duc to cornering or coning due to heating, it is made easier for the brake pads to be removed from contact with the rotor.

The release element may be formed unitarily with the resilient block. This simplifies the manufacture and assembly of the sub-assembly.

Deformation of the resilient block in response to the release force may decrease a contact area between the resilient block and the channel. Friction may be lowered by decreasing this contact area.

The release element may be shaped, or may interact with the resilient block, to transform the deformation of the release portion into the deformation of the resilient block.

The release element may interact with the resilient block such that a height of a portion of the resilient block is decreased as the resilient block is acted on by the release force.

The release element may be formed as an elongate protrusion within the recess of the resilient block.

The release element may be positioned such that the end portion deforms the release portion as the release force is applied.

At least one side wall of the resilient block may have a thickness that is greater at an end including the spring element than at an end including the release element.

The resilient block may include at least one peripheral groove on the bearing surface.

The peripheral groove may be configured to receive a guide element of the channel.

The peripheral groove may be configured to prevent or limit encapsulation of water between the resilient block and the channel.

The resilient block may be formed of an elastomeric material, such as a rubber clastomcr.

The resilient block may be formed of a heat-resistant material.

The material forming the elastomeric block may be a compound material including fibres or other filling materials. Such a material may provide the resilient properties along with heat-resistance suitable for operation at high temperatures.

According to a second aspect, there is provided a brake assembly comprising: a brake pad sub-assembly according to any preceding claim; and a brake caliper configured to apply the application force to the at least one brake pad of the brake pad sub-assembly upon initiation of a braking action by a user.

The brake pad may be configured to provide a braking action to a brake rotor response to the application force.

Two brake pads may be provided, the brake pads being positioned either side of the brake caliper and being configured to provide the braking action by damping the brake rotor therebetween.

Specific embodiments win now be described with reference to the accompanying drawings, in which: Figure 1 shows a perspective view of a brake assembly according to the second aspect; Figure 2 shows a perspective view of the brake assembly with the brake caliper removed, showing the brake pad sub-assembly beneath; Figure 3 depicts a sectional view of an end of the brake pad sub-assembly of Figure 2, showing the interaction of the brake pad with the resilient block and channel; Figure 4 shows a perspective view of the resilient block of Figure 3; Figure 5 shows the effect of a transfer of an application force from the brake pad to the resilient block; Figure 6 shows the effect transfer of a release force from the brake pad to the resilient block; Figure 7 shows a sectional view of the end of the brake pad sub-assembly of Figure 1, showing the guide element of the channel; and Figure 8 depicts a sectional view of an end of a different embodiment of a brake pad sub-assembly, showing the interaction of the brake pad with the resilient block.

Referring to Figure I. a brake pad assembly 100 is shown. The brake pad assembly 100 includes a bracket 102 that supports two opposed brake pads 104. A caliper 106 extends over the top of the brake pads 104 and acts to provide an application force to the brake pads 104, the application force being generated by a piston 108. The application force acts to move the brake pads 104 towards each other, which, when in position on a brake rotor, causes the brake pads 104 to clamp around the brake rotor to slow its rotation.

A brake pad sub-assembly, comprising the bracket 102 and brake pads 104, is shown in Figure 2. The perspective view is reversed when compared to Figure 1. Visible once the caliper 106 is removed, the bracket 102 is substantially U-shaped to extend around the brake pads 104 and supports the brake pads 104 via two channels 110 that extend along the sides of the bracket 102 in a direction between the two brake pads 104.

Movement of the brake pads 104 relative to this channel 110 therefore allows the clamping of the brake pads 104 around a brake rotor in response to an application force.

The brake pads 104 each include a central body 112 and two end portions 114. The central body 112 of each brake pad 104 includes a friction material 116 on a side that faces the other brake pad 104, such that this material comes into contact with the brake rotor during application of the brakes. The end portions 114 extend laterally from the sides of the central body 112 and have a substantially square cross-section.

The end portions 114 are received within the channels 112 of the bracket 102. The channels 110 are parafleh ensuring the ability for the end portions 114 to move freely along the channels 110.

A resilient block 118 is mounted on each end portion 114 and is interposed between the end portion 114 and the channel 110, preventing direct contact of the end portion 114 and the channel 110. Beneficially, the separation of the brake pad 104 and bracket 102, which are generally both metallic, by a resilient block 118, formed of a rubber elastomer or similar, prevents the creation of a galvanic cell between the components. In the present embodiment, the resilient block 118 also ensures that a gap is provided between the brake pad 104 and bracket 102, lowering the potential for wear.

Each resilient block 118 is dimensioned such that it fits snugly within its respective channel 110. in the depicted embodiment, as shown in Figure 3, the resilient blocks 118 are substantially square, with their height being approximately equal to that of the height of the channel 110. With no force applied to the brake pad 104, the end portions 114 are held substantially centrally within a recess 120 in the resilient block 118. This is achieved in the vertical direction (as defined in relation to the orientation shown in Figures 1 and 2) by the side walls 122 of the resilient block 118 having a thickness along part of their length to hold the resilient block 118 in the central position. The positioning is achieved in the lateral direction (as defined by the direction of the channel) by the provision of a spring element 124 and a release element 126.

The spring element 124 is situated on the left side of the recess 120 as viewed in Figures 3 to 6. The spring element 124 is formed unitarily with the resilient block 118 and extends inwards from a front wall 128 of the resilient block 118. The spring element 124 is formed as a substantially triangular shape with a width -i.e. the dimension of the spring element 124 extending between the sides 122 of the resilient block 118 -that is greater than its length -i.e. the dimension of the spring element 124 extending in the direction of the channel 110 As the spring element 124 is resilient, in this case due to its formation as a unitary portion of the resilient block 118, forces exerted on the spring element 124 will result in the compression of the spring clement 124 and the resultant storage of energy as strain energy within the spring element 124 and the resilient block 118 as a whole.

The spring element 124 will therefore provide a resistive force in response to this initial force and will act to provide a recoil force once this initial force is removed. In the present embodiment, the spring element 124, due to its shape, acts as a progressive spring, requiring more force to deform the more the spring element 124 deforms.

In use, the brake pads 104 will be subject to an application force to push them into engagement with the brake rotor in order to provide a braking force for a vehicle to which they are connected. The brake pads 104 will then transfer this force to the resilient blocks 118. As the resilient blocks 118 are in contact with the channel 110, a frictional force will be necessary to be overcome before any sliding movement of the resilient blocks 118 within the channels 110. The movement of the brake pads 104 will therefore necessarily result in a deformation of the spring element 124.

If the brake pads 104 must move a distance greater than that allowed by the deformation of the spring element 124, the resilient block 118 will then slide within the channel 110 until a point at which the brake pads 104 contact the brake rotor. Of course, during this movement the spring element 124 will remain deformed. Therefore, once the application force is removed -once the braking force is no longer required -the strain energy stored by the deformation of the spring dement 124 and resilient Hock 118 will be released in the form of a recoil force. The recoil force acts on the end portions 114 of the brake pad 104 in order to move the brake pad 104 away from the brake rotor. The spring element 124 therefore ensures that the brake pad 104 is separated from the brake rotor once the application force is removed.

In addition to providing energy storage, the spring element 124 of the described embodiment also acts to increase the frictional force between the resilient block 118 and the channel 110. This is achieved due to the shape of the spring element 124 transforming portions of the application force into a force directed towards the sides 122 of the resilient block 118. This transference of force is shown in Figure 5, The transference of force into vertical components not only increases the frictional force through increase of the normal force between the resilient block 118 and the channel 110 but also deforms the resilient block 118 such that there is a greater surface area of the resilient block 118 in contact with the channel 110. The result of this is that as the application force is increased on spring element 124, the static friction& force exhibited between the resilient block 118 and the channel 110 will simultaneously be increased up to a point at which it is overcome by the application force.

The release clement 126 is provided on the opposing, rear wall 130 of the resilient block 118. Similarly to the spring element 124, the release element 126 extends into the recess 120 of the resilient block 118, parallel to the lengthwise direction of the channel 110. The release element 126 is configured such that a force acting on it in a direction away from the brake rotor -i.e. the opposite direction to that of the application force -reduces the resistance of the resilient block 118 to movement, lowering the force required to move the brake pads 104.

The release dement 126 operates with the resilient block 118 to reduce the frictional force of the resilient block 118 on the channel 110. As can be seen in Figure 6, the resilient block 118 has a more elongate form than the spring element 124 and therefore its interaction with the rear wall 130 of the resilient block 118 is slightly different. When a release force is exerted on the release element 126 in the opposite direction to the application force, the release element 126 transforms a portion of this force into a vertical force that pulls a portion of the sides 122 of the resilient block 118 away from the walls 122 of the channel 110. In this way, the normal force between the resilient block 118 and the channel 110 is reduced, alongside a reduction in the area of the resilient block 118 that contacts the channel 110. Thus, the frictional force between the resilient block 118 and the channel 110 will be reduced.

By reducing the frictional force between the resilient block 118 and the channel 110, the result of applying a release force to the release clement 126 is to lower the force required to move the resilient block 118, and therefore the brake pads 104, along the channels 110 away from engagement with the rotor.

In use, the brake pads 104 may sometimes be subjected to a release force imparted from other parts of the assembly, for example the brake rotor. Such forces may commonly be attributable to cornering forces acting on the brake rotor causing deflection thereof, or by heating of the brake rotor causing coning thereof, although other causes are also possible. In such a situation, it is desirable to enable the brake pads 104 to move under influence of the release force to a position where they are no longer in contact with the brake rotor.

With the release force therefore being applied to the brake rotor, this force is transferred via the end portions 114 of the brake pads 104 to the resilient blocks 118.

The end portions 114 are moved into the release elements 126, causing the above-mentioned deflection of the release element 126 and resilient block 118. The force required to move the resilient block 118 is therefore lowered and the brake pads 104 can move more easily away from contact with the brake rotor.

From Figure 6, it can be seen that the thickness of the side walls 122 of the resilient block 118 changes along their length. More specifically, the side walls 122 are thicker at an end adjacent to the spring element 124 than at an end adjacent to the release element 126. The thickness is constant along substantially half of the length of the side wall 122, before ramping down to a decreased thickness for the quarter of the side wall 122 that is closest to the release clement 126. The decreased thickness is, in the present embodiment, approximately half the thickness of the side wall 122 at the spring element 124. By decreasing the thickness of the side wall 122, deflection of the rear wall 130 of the resilient block 118 in response to the release force is made easier.

The position and amount of the decrease in thickness may be varied away from the specifics noted in relation to the depicted embodiment. These are simply options used to illustrate this feature and the skilled person will be aware that they may vary. It is also noted that the change in thickness is not a requirement for the functioning of the release element 126, although it may be advantageous in some embodiments.

It can be seen in Figures 4 to 6 that a groove extends across both of the side walls 122 of the resilient block 118 in a direction parallel to the direction of the channel 110. The groove 132 extends partially through the thickness of the side walls 122 and is located substantially centrally along each side wall 122.

In Figure 7, one use of the groove 132 is shown. The groove 132 receives a guide element 134 that is formed on the upper and lower surfaces of the channel 110 and extends along the length of the channel 110. The interaction of the groove 132 and the guide clement 134 ensures that the resilient block 118 remains within the channel 110 and helps to guide the brake pad 104 during movement.

The groove 132 may, additionally or alternatively, be provided to assist with the channelling of water away from the surfaces of the channel 110. Akin to the tread of a tyre, the groove 132 can act to allow water to drain from the surface of the channel 110 into the groove 132, from which it can then escape from the end of the groove 132. By channelling water away from the surfaces of the channel 110, undesirable altering of the frictional properties of the channel 110 and resilient block 118 can be reduced.

A further embodiment is shown in Figure 8. The cross-sectional view is the same as that of Figure 3 and includes the end portion 214 of a brake pad, the channel 210, and a resilient block 218. In this second embodiment, the end portion 214 includes a detachable cap 236. The detachable cap 236 can be removed to allow the assembly of the resilient block 218, which in this case includes a central aperture 238, onto a boss 240 defined by the end portion 214. The detachable cap 236 can then be attached in order to secure the resilient block 218 in position on the boss 240.

The resilient block 218 includes an aperture 238 such that it may be received on the boss 240 but has a square cross-section along the length of the channel 210 in order to present a flat bearing surface to the channel 210. The aperture 238 and boss 240 fit snugly and are both circular in the present embodiment, although other shapes may be used.

It will be apparent that, rather than moving within the resilient block as in the first embodiment, the end portion 214 of the second embodiment pushes on the outside of the resilient block 218. As such, the spring element 224 and release element 226 are positioned on the outside of the resilient block 218.

When an application force acts on the brake pad, the end portion 214 will therefore push on the spring element 224 from the outside. This will cause deformation of the spring dement 224, storing energy that can then be released as a recoil force as in the first embodiment. The spring element 224 is also still shaped such that its deformation causes force to be transferred to a vertical direction to increase friction.

Similarly, when the release force acts on the brake pad the release element 226 will be pushed on by the end portion 214 from the outside. The release element 226 is shaped such that this will result in a decrease in the frictional force, as described in relation to the first embodiment.

Although the described resilient blocks 218 have specific shapes of spring element 224 and release element, different shapes may also be used. Multiple different arrangements may result in the required transfer of force and/or cause deformation of the resilient block 218 in the required manner and the present application is not intended to be limited to any one specific arrangement, unless specified in the claims.

The resilient block of any embodiment may be tuned in order that it reacts predictably under the forces likely to be imparted upon it. For example, different material compositions may be used, or the resilient block may be adapted in its shape and/or volume. Such changes will alter both how the resilient block deforms when subjected to forces as well as how the resilient block interacts with the channel In order that different resilient blocks may be readily identified, for example such that resilient Hocks with different properties are not applied to the incorrect brake pad assembly, the resilient blocks may include identifying marks. The identifying marks may be codes, numbers, stripes, or some form of colour coding. In one example, the colour of the material making up the resilient block may correspond to the material properties of the resilient block.

Claims

CLAIMSA brake pad sub-assembly comprising: a bracket comprising a channel; at least one brake pad supported by the bracket and configured to slide along the channel in response to an application force in an engagement direction; wherein the brake pad includes an end portion configured to be seated within the channel and upon which a resilient block is mounted; wherein the resilient block includes a bearing surface that bears upon the channel, a recess within which the end portion is seated, and a spring element configured to deform in response to the application force, the spring element subsequently providing a recoil force in a disengagement direction opposite to the engagement direction when the application force is lowered or removed.
2. A brake pad sub-assembly according to claim 1, wherein the spring element is formed unitarily with the resilient block.
3. A brake pad sub-assembly according to claim 1 or claim 2, wherein deformation of the spring element in response to the application force causes deformation of the resilient block such that there is an increase in friction between the resilient block and the channel.
4. A brake pad sub-assembly according to claim 3, wherein deformation of the resilient block in response to the application force increases a contact area between the resilient block and the channel
5. A brake pad sub-assembly according to claim 3 or claim 4, wherein the spring element interacts with the resilient block to transform the deformation of the spring element into the deformation of the resilient block.
6. A brake pad sub-assembly according to any preceding claim, wherein the spring element is formed as a triangular protrusion within the recess of the resilient block.
7. A brake pad sub-assembly according to claim 6, wherein the triangular protrusion has a greater width than length.
8. A brake pad sub-assembly according to ally preceding claim, wherein the brake pad is configured to slide along the channel once friction between the resilient block and channel is overcome.
9. A brake pad sub-assembly according to any preceding claim, wherein the spring dement is positioned such that the end portion deforms the spring element as the application force is applied.
10. A brake pad sub-assembly according to any preceding claim, wherein the resilient block further includes a release element that acts to deform the resilient Hock to lower friction between the resilient block and the channel when a release force is applied to the brake pad in the disengagement direction.
11. A brake pad sub-assembly according to claim 10, wherein the release element is formed unitarily with the resilient block.
12. A brake pad sub-assembly according to claim 10 or claim 11, wherein deformation of the resilient block in response to the release force decreases a contact area between the resilient block and the channel.
13. A brake pad sub-assembly according to any of claims 10 to 12, wherein the release element interacts with the resilient block to transform the deformation of the release portion into the deformation of the resilient block.
14. A brake pad sub-assembly according to any of claims 10 to 13, wherein the release element interacts with the resilient block such that a height of the resilient block is decreased as the release element is acted on by the release force
15. A brake pad sub-assembly according to any of claims 10 to 14, wherein the release element is formed as an elongate protrusion within the recess of the resilient block.
16. A brake pad sub-assembly according to any of claims 10 to 15, wherein the release element is positioned such that the end portion deforms the release portion as the release force is applied.
17. A brake pad sub-assembly according to any of claims 10 to 16, wherein at least one side wall of the resilient block has a thickness that is greater at an end including the spring element than at an end including the release element.
18. A brake pad sub-assembly according to any preceding claim, wherein the resilient block includes at least one peripheral groove on the bearing surface.
19. A brake pad sub-assembly according to claim 18, wherein the peripheral groove is configured to receive a guide element of the channel.
20. A brake pad sub-assembly according to claim 18 or claim 19, wherein the peripheral groove is configured to prevent or limit encapsulation of water between the resilient block and the channel.
21. A brake pad sub-assembly according to any preceding claim, wherein the resilient block is formed of an elastomeric material, such as a rubber elastomer.
22. A brake pad sub-assembly according to any preceding claim, wherein the elastomeric material is formed of a heat-resistant material.
23. A brake assembly comprising: a brake pad sub-assembly according to any preceding claim and a brake caliper configured to apply the application force to the at least one brake pad of the brake pad sub-assembly upon initiation of a braking action by a user.
24. A brake assembly according to claim 23, wherein the brake pad is configured to provide a braking action to a brake rotor in response to the application force.
25. A brake assembly according to claim 23 or claim 24, wherein two brake pads are provided, the brake pads being positioned either side of the brake caliper and being configured to provide the braking action by clamping the brake rotor th ereb etwe en.