Air disc brake pad assembly and method

Abstract

A method of providing a poka-yoke to prevent incorrect assembly of an air disc brake pad (14) to a brake caliper; the method comprising providing a brake caliper having a first set of brake pad carriers (12), and a second brake caliper having a second set of brake pad carriers (60); each set of brake pad carriers (12, 60) having an inner side (24) and first and second ends 26, 28 for receiving a brake pad (14, 50) the pad being retained in the carrier by a pad retainer 40, and an axis running centrally through the brake pad carriers from end to end, the axis being parallel or substantially so, with the inner side of the brake pad carrier; the first and second ends of the first set of brake pad carriers extending perpendicularly to the axis for receiving brake pads where a vertical pad abutment and a horizontal pad abutment lie perpendicular to one another; the first and second ends 36, 38 of the second set of brake pad carriers extending angularly offset to the perpendicular to the axis for receiving brake pads where the end pad abutments are correspondingly angularly offset from the vertical lying perpendicular to a horizontal pad abutment; and the first brake pads fitting only into the first set of brake pad carriers and not the second set of brake pad carriers, and the second set of brake pads fitting only into the second set of brake pad carriers and not the first set of brake pad carriers.

Description

[0001] Air Disc Brake Pad Assembly And Method

[0002] Description

[0003] The present invention relates to a method of providing a poka-yoke to prevent incorrect assembly of an air disc brake pad to a brake caliper, an air disc brake pad, and an air disc brake pad carrier.

[0004] BACKGROUND TO THE INVENTION

[0005] In an air disc brake for a commercial vehicle, including a heavy goods vehicle, brake calipers actuate brake pads against a rotating disc during braking. The brake pads are a wearable component and need replacing when the friction material on the brake pad wears to a predefined limit. It is important that the replacement brake pads are assembled correctly to the brake caliper.

[0006] Brake pads can be made from different friction materials, suited for particular applications. For example, the friction material specified for a bus may be different to that of a truck.

[0007] As shown in Figure 1 , brake calipers include brake pad carriers which receive the brake pads.

[0008] Different calipers will generally receive pads of different shapes. However, the same calipers can receive pads of different friction materials. This can result in the insertion of brake pads with friction materials which may not be suited to that vehicle.

[0009] To indicate whether the brake pad is of a friction material suited for the vehicle, text marking and colour coding can be used. However, this does not prevent a user from fitting an unsuitable brake pad (e.g. a brake pad with a friction material suited to a truck, where a brake pad with a friction material suited to a bus is required).

[0010] It is an object of the present invention to reduce or substantially obviate the aforementioned problems. STATEMENT OF INVENTION

[0011] According to a first aspect of the present invention there is provided a method of providing a poka-yoke to prevent incorrect assembly of an air disc brake pad to a brake caliper; the method comprising providing a brake caliper having a first set of brake pad carriers, and a second brake caliper having a second set of brake pad carriers; each set of brake pad carriers having an inner side and first and second ends for receiving a brake pad, the pad being retained in the carrier by a pad retainer, and an axis running centrally through the brake pad carriers from end to end, the axis being parallel or substantially so, with the inner side of the brake pad carrier; the first and second ends of the first set of brake pad carriers extending perpendicularly to the axis for receiving brake pads where a vertical pad abutment and a horizontal pad abutment lie perpendicular to one another; the first and second ends of the second set of brake pad carriers extending angularly offset to the perpendicular to the axis for receiving brake pads where the end pad abutments are correspondingly angularly offset from the vertical lying perpendicular to a horizontal pad abutment; and the first brake pads fitting only into the first set of brake pad carriers and not the second set of brake pad carriers, and the second set of brake pads fitting only into the second set of brake pad carriers and not the first set of brake pad carriers.

[0012] The method can be used to prevent the fitting of an ill-suited brake pad to each of the brake pad carriers.

[0013] The first set of brake pad carriers may be used in a first type of vehicle, e.g. a truck, requiring brake pads with a friction material of the first brake pads. The second set of brake pad carriers may be used in a second type of vehicle, e.g. a bus, requiring brake pads with a friction material of the second brake pads.

[0014] The angular offset of the first and second ends of the second brake pad carrier prevents the insertion of the first type of brake pad into the second brake pad carrier and vice versa. This “fool-proofs” the fitting of the correct brake pads for each type of brake pad carrier.

[0015] The first and second ends of the second set of brake pad carriers may be angularly offset by different angles. Alternatively, the first and second ends of the second set of brake pad carriers may be parallel (i.e., offset by the same angle in the same direction) for receiving brake pads where the end pad abutments are correspondingly parallel.

[0016] Alternatively, the first and second ends of the second set of brake pad carriers may be angularly offset from the vertical by substantially the same angle in opposing directions. In other words, the first and second ends may be mirror images of each other.

[0017] Providing the angular offset of the first and second ends in the same angle in opposing directions is advantageous. The resulting symmetry between the first and second ends of the corresponding brake pad carrier may mitigate against the development of unusual wear patterns. The symmetry between the first and second ends may mitigate against non-uniform stresses being applied to the brake pad when the brake is operating in opposite directions (e.g. where the brake pad is fitted to an opposite side of a vehicle).

[0018] The brake pads may be substantially symmetrical. The symmetry may be about a central vertical axis extending perpendicular to the central horizontal axis. As discussed above with respect to the symmetrical angular offsets, this may provide uniform stresses when the brake pad is operating in opposite directions. The brake pads may include abutment tabs or ears. The abutment tabs may provide horizontal abutment between the brake pad and the brake pad carrier. The first and second ends of the brake pads may provide vertical abutment between the brake pad and the brake pad carrier.

[0019] The angular offset of the first and second ends of the brake pad carrier may mitigate the distance the brake pad can drop should the abutment tabs fracture. Reducing the distance the brake pad drops following the fracture may ensure alignment between the brake pad and disc is maintained.

[0020] According to a second aspect of the present invention, there is provided an air disc brake pad, the brake pad including a backplate and a friction material mounted on one side of the backplate, the pad periphery including and inner side, an outer side, and first and second ends, in use, the inner side and first and second ends sitting in a brake pad carrier of a brake caliper and being retained by a pad retainer on the outer side, a central horizontal axis running between the first and second ends of the brake pad, and the first and second ends being angularly offset from a perpendicular to the axis, and in which the friction material is of a particular type for use in a particular application and corresponds to the angular offset of the brake pad ends.

[0021] The angular offsets of the first and second ends of the brake pad ensure that the brake pad can only be fitted to a brake pad carrier with corresponding angular offsets. By providing a brake pad with a friction material which corresponds to angular offsets, only the brake pad with the friction material of a particular type can only be inserted into the brake pad carrier of that type.

[0022] The air disc brake pad may comprise any feature or combination of features of the brake pads of the first aspect of the present invention. The first and second ends may be angularly offset by substantially 3° to 20°. For example, the first and second ends may be angularly offset by substantially 4° to 15°. For example, the first and second ends may be angularly offset by substantially 5° to 10°. For example, the first and second ends may be angularly offset by substantially 6° to 8°.

[0023] The first and second ends of the brake pad may be angularly offset by different angles. Alternatively, the first and second ends may be parallel (i.e., offset by the same angle in the same direction).

[0024] Alternatively, the first and second ends may be angularly offset from the vertical by substantially the same angle in opposing directions. In other words, the first and second ends may be mirror images of each other.

[0025] The brake pad may be substantially symmetrical. The symmetry may be about a central vertical axis extending perpendicular to the central horizontal axis.

[0026] According to a third aspect of the present invention, there is provided an air disc brake pad carrier of a brake caliper, the brake pad carrier having an inner side and first and second ends and a central horizontal axis running centrally through the brake pad carrier from the first end to the second end, the central horizontal axis being parallel or substantially so, with the inner side; the first and second end of the brake pad carrier extending angularly offset to the perpendicular to the axis; in which the angular offset of the first and second ends corresponds to a friction material of a particular type.

[0027] The angular offsets of the first and second ends of the brake pad carrier ensure that only a brake pad with corresponding angular offsets can be inserted. The brake pad carrier is configured to receive a brake pad with a particular friction material corresponding to the angular offsets of first and second ends of the brake pad. This ensures that the brake pad carrier can only receive brake pads which include a suitable friction material.

[0028] The air disc brake pad carrier may comprise any feature or combination of features of the brake pad carriers of the first and second aspects of the present invention.

[0029] The first and second ends of the brake pad carrier may be angularly offset by different angles. Alternatively, the first and second ends may be parallel (i.e., offset by the same angle in the same direction).

[0030] Alternatively, the first and second ends may be angularly offset from the vertical by substantially the same angle in opposing directions. In other words, the first and second ends may be mirror images of each other.

[0031] The inner side and first and second ends may define a brake pad receiving region. The brake pad receiving region may be substantially symmetrical. The symmetry may be about a central vertical axis extending perpendicular to the central horizontal axis.

[0032] BRIEF DESCRIPTION OF THE DRAWINGS

[0033] For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings, in which:

[0034] Figure 1 shows a conventional brake pad inserted into a conventional brake pad carrier;

[0035] Figure 2 shows a side view of a first brake pad assembly including a brake pad carrier and corresponding brake pad according to the present invention; Figure 3a shows a side view the brake pad carrier of Figure 2 with an incompatible brake pad;

[0036] Figure 3b shows a side view the brake pad of Figure 2 with an incompatible brake pad carrier; and

[0037] Figure 4 shows a side view of a second brake pad assembly including a brake pad carrier and corresponding brake pad according to the present invention.

[0038] DESCRIPTION OF PREFERRED EMBODIMENTS

[0039] Referring firstly to Figure 2, an air disc brake pad assembly according to the present invention is generally shown at 10. The brake pad assembly 10 includes an air disc brake pad carrier 12. The air disc brake pad carrier 12 is part of an air disc brake. The air disc brake pad carrier 12 is part of a pair of brake pad carriers in the air disc brake. The air disc brake pad carriers 12 are disposed on opposite sides of a brake disc.

[0040] The brake pad assembly 10 includes an air disc brake pad 14. During use, the brake pad 14 is disposed within the brake pad carrier 12. The brake pad assembly 10 prevents incompatible brake pads from being inserted into incompatible brake pad carriers as described below.

[0041] The brake pad carrier 12 has a base or inner side 16. The brake pad carrier has a first side wall 18. The first side wall 18 extends substantially perpendicular from a first end of the base 16. The brake pad carrier 12 has a second side wall 20. The second side wall 20 extends substantially perpendicular from a second end of the base 16. The second side wall 20 opposes the first side wall 18. The base 16 and side walls 18, 20 define a brake pad receiving region.

[0042] The brake pad receiving region has an inner side 24. The inner side 24 extends along the length of the base 16. The brake pad receiving region has a first end 26. The first end 26 extends along the length of the first side wall 18. The brake pad receiving region has a second end 28. The second end 28 extends along the length of the second side wall 20. The inner side 24 and first and second ends 26, 28 define a surface with a substantially U-shaped cross-section.

[0043] A horizontal axis extends from the first end 26 to the second end 28 which is substantially parallel to the inner side 24. A first angle between the first end 26 and the horizontal axis is offset from the perpendicular to the axis. A second angle between the second end 28 and the horizontal axis is offset from the perpendicular to the axis.

[0044] In this embodiment, the first angle is offset by 5°. The angle is offset in a direction away from the second side wall 20. In other words, an angle between the inner side 24 and the first end 26 in 95°. It will be appreciated that in other embodiments, the first angle may by offset by substantially 3° to 20°. Preferably, the first angle is offset by substantially 5° to 10°.

[0045] In this embodiment, the second angle is offset by 5°. The angle is offset in a direction away from the first side wall 18. In other words, an angle between the inner side 24 and the second end 26 in 95°. It will be appreciated that in other embodiments, the second angle may by offset by substantially 3° to 20°. Preferably, the second angle is offset by substantially 5° to 10°.

[0046] The brake pad 14 can be received in the brake pad carrier 12. The brake pad 14 includes a backplate 29. The brake pad includes a friction material. The friction material is mounted on one side of the backplate 29.

[0047] The brake pad 14 includes a pad periphery 30. The pad periphery 30 includes an inner side 32. The inner side 32 of the pad periphery 30 faces the inner side 24 of the brake pad carrier 12 during use. The pad periphery 30 includes an outer side 34. The outer side 34 of the pad periphery 30 opposes the inner side 32 of the brake pad periphery 30. The pad periphery 30 includes a first end 36. The first end 36 of the pad periphery 30 faces the first end 26 of the brake pad carrier 12 during use. The pad periphery 30 includes a second end 38. The second end 38 of the pad periphery 30 faces the second end 28 of the brake pad carrier 12 during use.

[0048] A central horizontal axis extends from the first end 36 to the second end 38. The central horizontal axis is substantially parallel to the inner side 32. A first angle between the first end 36 and the horizontal axis is offset from the perpendicular to the axis. A second angle between the second end 38 and the horizontal axis is offset from the perpendicular to the axis.

[0049] In this embodiment, the first angle is offset by 5°. The angle is offset in a direction away from the second side wall 20. In other words, an angle between the inner side 32 and the first end 36 in 95°. The first angle of the brake pad 14 corresponds to the first angle of the brake pad carrier 12.

[0050] It will be appreciated that in other embodiments, the first angle may by offset by 5° to 10°, corresponding to the angular offset of the first angle of the brake pad carrier 12.

[0051] In this embodiment, the second angle is offset by 5°. The angle is offset in a direction away from the first side wall 18. In other words, an angle between the inner side 32 and the second end 36 in 95°. The second angle of the brake pad 14 corresponds to the second angle of the brake pad carrier 12.

[0052] It will be appreciated that in other embodiments, the second angle may by offset by 5° to 10°, corresponding to the angular offset of the second angle of the brake pad carrier 12.

[0053] Once inserted, the first and second ends 36, 38 of the brake pad 14 abut the first and second ends 26, 28 of the brake pad carrier. The first and second ends 36, 38 of the brake pad 14 provide vertical abutment between the brake pad 14 and the brake pad carrier 12.

[0054] The brake pad 14 includes abutment tabs 42 or “ears”. The abutment tabs 42 protrude from the first and second ends 36, 38 of the brake pad 14. During use, the abutment tabs 42 sit above the first and second side walls 18, 20. The abutment tabs 42 provide horizontal abutment between the brake pad 14 and the brake pad carrier 12.

[0055] During use, the brake pad 14 is retained by a pad retainer 40 on the outer side 34.

[0056] The angular offsets of the brake pad carrier 12 and brake pad 14 correspond to types of friction materials 52. The corresponding angular offsets of the brake pad 14 and the brake pad carrier 12 ensure that the brake pad carrier 12 requiring a brake pad with a particular friction material can only receive the corresponding brake pad with the friction material and vice versa.

[0057] Referring to Figure 3a, a first incompatible set of a brake pad 50 and a brake pad carrier 12 is shown.

[0058] In Figure 3a, the brake pad carrier 12 is as discussed above with first and second angles having an angular offset of 5°. The brake pad carrier 12 has a first width 80 extending between the first and second ends 26, 28 at a top of the brake pad carrier 12 proximal to the pad retainer 40. The brake pad carrier 12 has a second width 82 extending between the first and second ends 26, 28 at a bottom of the brake pad carrier 12 distal from the pad retainer 40. The first and second angles of brake pad 50 do not include the angular offset corresponding to the friction material required by the brake pad carrier 12. A width between first and second ends of the brake pad 50 is substantially the same at both the top and bottom of the brake pad 50.

[0059] In the pad assembly of Figure 3a, the brake pad 50 cannot be fully inserted into the brake pad carrier 12. As the brake pad 50 is inserted, the brake pad 50 can only be inserted a portion of the way into the carrier 12 before the first and second ends of the brake pad 50 abut the first and second ends 26, 28 of the brake pad carrier 12. In other words, the brake pad 50 reaches a point at which the space between the first and second ends 36, 38 of the brake pad carrier 12 is too narrow for the brake pad 50 to be inserted further. The width of the brake pad 50 is greater than the second width 82 of the brake pad carrier 12. The angular offset of the first and second ends 26, 28 of the brake pad carrier 12 prevent the brake pad 50 from being fully inserted because the brake pad 50 does not include corresponding angular offsets. The brake pad 50 cannot be fully inserted and the pad retainer 40 cannot retain the brake pad. The operator replacing the brake pad 50 will realise that the pad 50 cannot be moved further and that therefore the brake pad 50 and brake carrier 12 are incompatible.

[0060] The insertion of a brake pad 50 with a friction material incompatible with the brake pad carrier 12 is prevented.

[0061] Referring now to Figure 3b, a second incompatible set of a brake pad 14 and a brake pad carrier 60 is shown.

[0062] In Figure 3b, the brake pad 14 is as discussed above with first and second angles having an angular offset of 5°. The first and second angles of brake pad carrier 60 do not include the angular offset corresponding to the friction material of the brake pad 14. A width 84 between first and second ends of the brake pad carrier 60 is substantially the same at both the top and bottom of the brake pad carrier 60.

[0063] In the pad assembly of Figure 3b, the brake pad 14 cannot be fully inserted into the brake pad carrier 60. As the brake pad 14 is inserted, the brake pad 14 can only be inserted a portion of the way into the carrier 60 before the first and second ends 36, 38 of the brake pad 14 abut the first and second ends of the brake pad carrier 60. In other words, the brake pad 14 reaches a point at which the brake pad 14 is too wide to be inserted further.

[0064] The angular offset of the first and second ends 36, 38 of the brake pad 14 prevent the brake pad 14 from being fully inserted because the brake pad carrier 60 does not include corresponding angular offsets in the first and second ends. The brake pad 14 cannot be fully inserted and the pad retainer 40 cannot retain the brake pad 14. The operator replacing the brake pad 14 will realise that the pad 14 cannot be moved further and that therefore the brake pad 14 and brake carrier 60 are incompatible. The insertion of the brake pad 14 with a friction material incompatible with the brake pad carrier 60 is prevented.

[0065] Referring now to Figure 4, a second embodiment of the pad assembly is generally shown at 100. The features of the pad assembly 100 are substantially similar to that of the first embodiment 10. Differences between the first and second embodiment are discussed below.

[0066] In this embodiment, the first and second angles of the brake pad carrier 120 are offset by 5° in the same direction. The angles are offset in a direction away from the first side wall 180. In other words, the angle between the horizontal axis and the first end 260 is 85°. The angle between the horizontal axis and the second end 280 is 95°.

[0067] In other words, the first end 260 and the second end 280 of the brake pad carrier 120 are substantially parallel to each other.

[0068] It can be seen that, as in the first embodiment, the angular offsets of the brake pad 140 correspond to the angular offsets of the brake pad carrier 120. In other words, the first and second ends 360, 380 of the brake pad 140 are parallel to each other. During use the brake pad 140 is retained by the pad retainer 400.

[0069] The brake pad 14 with angular offsets in opposing directions would not be able to be inserted into the brake pad carrier 120. The angular offsets of the brake pad carrier 120 prevent full insertion of the brake pad 14 across its full width because the space between the first and second ends 260, 280 is too narrow.

[0070] The significant advantage of the brake pad assemblies described above is that the brake pads can only be fully inserted into brake pad carriers of the corresponding angular offset and therefore can only be inserted into brake pad carriers of the correct friction material type. For example, the insertion of a brake pad with a friction material suited for a truck cannot be inserted into a brake pad carrier of a bus. Only brake pads with the correct type of friction material and the corresponding angular offset can be inserted into the brake pad carrier. Where a brake pad cannot be fully inserted, the operator is alerted to the fact that the brake pad is incompatible with the brake pad carrier thereby “fool-proofing” the correct assembly of the brake pad assembly.

[0071] The embodiments described above are provided by way of example only, and various changes and modifications will be apparent to persons skilled in the art without departing from the scope of the present invention as defined by the appended claims.

Claims

Claims1 . A method of providing a poka-yoke to prevent incorrect assembly of an air disc brake pad to a brake caliper; the method comprising providing a brake caliper having a first set of brake pad carriers, and a second brake caliper having a second set of brake pad carriers; each set of brake pad carriers having an inner side and first and second ends for receiving a brake pad, the pad being retained in the carrier by a pad retainer, and an axis running centrally through the brake pad carriers from end to end, the axis being parallel or substantially so, with the inner side of the brake pad carrier; the first and second ends of the first set of brake pad carriers extending perpendicularly to the axis for receiving brake pads where a vertical pad abutment and a horizontal pad abutment lie perpendicular to one another; the first and second ends of the second set of brake pad carriers extending angularly offset to the perpendicular to the axis for receiving brake pads where the end pad abutments are correspondingly angularly offset from the vertical lying perpendicular to a horizontal pad abutment; and the first set of brake pads fitting only into the first set of brake pad carriers and not the second set of brake pad carriers, and the second set of brake pads fitting only into the second set of brake pad carriers and not the first set of brake pad carriers.

2. A method of providing a poka-yoke as claimed in claim 1 , in which the first and second ends of the second set of brake pad carriers are parallel for receiving brake pads where the end pad abutments are correspondingly parallel.

3. A method of providing a poka-yoke as claimed in claim 1 , in which the first and second ends of the second set of brake pad carriers are angularly offset from the vertical by substantially the same angle in opposing directions.

4. A method of providing a poka-yoke as claimed in any preceding claim, in which the first brake pads and second set of brake pads comprise different friction materials.

5. An air disc brake pad, the brake pad including a backplate and a friction material mounted on one side of the backplate, the pad periphery including an inner side, an outer side, and first and second ends, in use, the inner side and first and second ends sitting in a brake pad carrier of a brake caliper and being retained by a pad retainer on the outer side, a central horizontal axis running between the first and second ends of the brake pad, the axis being parallel or substantially so, with the inner side of the brake pad; the first and second ends being angularly offset from a perpendicular to the axis; and in which the friction material is of a particular type for use in a particular application and corresponds to the angular offset of the brake pad ends.

6. An air disc brake pad, as claimed in claim 5, in which the first and second ends extend parallel to each other.

7. An air disc brake pad, as claimed in claim 5, in which the first and second ends are angularly offset from the vertical by substantially the same angle in opposing directions.

8. An air disc brake pad, as claimed in claim 7, in which the brake pad is substantially symmetrical about a central vertical axis extending perpendicular to the central horizontal axis.

9. An air disc brake pad, as claimed in any of claims 5 to 8, in which the brake pad includes abutment tabs extending from at least one of the first and second ends for providing horizontal abutment with the brake pad carrier.

10. An air disc brake pad carrier of a brake caliper, the brake pad carrier having an inner side and first and second ends and a central horizontal axis running centrally through the brake pad carrier from the first end to the second end, the central horizontal axis being parallel or substantially so, with the inner side; the first and second ends of the brake pad carrier extending angularly offset to the perpendicular to the axis, in which the angular offset of the first and second ends corresponds to a friction material of a particular type.

11. An air disc brake pad carrier, as claimed in claim 10, in which the first and second ends extend parallel to each other.

12. An air disc brake pad carrier, as claimed in claim 10, in which the first and second ends are angularly offset from the vertical by substantially the same angle in opposing directions.

13. An air disc brake pad carrier, as claimed in claim 12, in which the inner side and first and second ends define a brake pad receiving region, and wherein the brake pad receiving region is substantially symmetrical about a central vertical axis extending perpendicular to the central horizontal axis.

Images