AUTOMATIC SLACK ADJUSTER FOR BRAKING SYSTEMS OF AUTOMOTIVE VEHICLES, BRAKING SYSTEM AND CORRESPONDING WHEELS

Abstract

An automatic slack adjuster (1, 101, 201) for braking systems of automotive vehicles, in particular for drum brakes of commercial vehicles, includes a lever (3, 103, 203) configured to be operatively coupled to a push rod (117, 217) of a brake actuator, and to pivot about a rotational axis (R) when actuated by the push rod (117, 217), the rotational axis (R) having a predetermined fixed location relative to the vehicle. The stroke level of the slack adjuster (1, 101, 201) is moveable between a predetermined zero stroke position (7a, 107a, 207a) and a working stroke range (7b). The invention furthermore relates to a braking system (100) for an automotive vehicle and a wheelset (200) can include the slack adjuster. An electronic detection unit (98, 109, 209) determines the current stroke level of the automatic slack adjuster (1, 101, 201).

Claims

1. An automatic slack adjuster (1, 101, 201) for a braking system of an automotive vehicle, the automatic slack adjuster comprising: a lever (3, 103, 203) configured to be operatively coupled to a push rod of a brake actuator, wherein the lever pivots about a rotational axis (R) when actuated by the push rod (117, 217), the rotational axis (R) having a predetermined fixed location relative to the vehicle, wherein a stroke level of the slack adjuster (1, 101, 201) is moveable between a predetermined zero stroke position (7a, 107a, 207a) and a working stroke range (7b), and an electronic detection unit (9, 109, 209) that determines a current stroke level of the automatic slack adjuster (1, 101, 201).

2. The automatic slack adjuster (1) of claim 1, wherein the electronic detection unit (9) comprises: a stroke indicator element (11) positioned on the automatic slack adjuster (1) such that the lever (3) pivots relative to the stroke indicator element (11) about the rotational axis (R) as a function of the current stroke level of the automatic slack adjuster (1), and a sensor arrangement (13) positioned on the lever (3) in the proximity of the indicator element (11), wherein the sensor arrangement (13) determines a position of the indicator element (13) relative to the sensor arrangement (9).

3. The automatic slack adjuster (1) of claim 2, wherein the sensor arrangement (13) comprises at least one of an inductive sensor, a capacitance sensor, or a hall sensor.

4. The automatic slack adjuster (1) of claim 2, wherein the stroke indicator element (11) further comprises a mounting piece (5) configured to attach the stroke indicator element (11) in a fixed location to the vehicle.

5. The automatic slack adjuster (101) of claim 1, wherein the electronic detection unit (109) comprises: a link (119) that is pivotably coupled to the lever (103) and abuts against a push rod (117) that is operatively coupled to the lever and that actuates lever, and a sensor arrangement (113) arranged at the lever (103), wherein the sensor arrangement (113) determines a relative angle (121) between the link (119) and the lever (103) that is indicative of a current stroke level of the automatic slack adjuster (101).

6. The automatic slack adjuster (101) of claim 5, wherein the sensor arrangement (113) comprises an angular sensor (123) that determines the relative angle (121) between the link (119) and the lever (103).

7. The automatic slack adjuster (101) of claim 5, wherein the link (119) includes a spring element (125) that forces the link (119) against the push rod (117).

8. The automatic slack adjuster (101) of claim 7, wherein the spring element (125) is a torsion spring (127).

9. The automatic slack adjuster (201) of claim 1, wherein the electronic detection unit (209) comprises: a first link (231) that is pivotably coupled to the lever (203) and a second link (229) that is pivotably coupled to a push rod (217) that is operatively coupled to the lever and that actuates the lever, wherein the first link (231) and the second link (229) are coupled to one another by way of a slot guide (233) such that the first and second links (231, 229) slide relative to one another as a function of the current stroke level of the automatic slack adjuster (201), and a sensor arrangement (213) that determines a relative position of the first link (231) to the second link (229) at the slot guide (233).

10. The automatic slack adjuster (201) of claim 9, wherein the sensor arrangement (213) is positioned at the second link (231).

11. The automatic slack adjuster (1, 101, 201) of claim 1, wherein the rotational axis (R) is oriented coaxially to a rotating brake shaft of a braking system.

12. A braking system (1000) for an automotive vehicle, the braking system comprising: a brake actuator (1010) having a push rod (1030), a brake mechanism (1070) that applies a braking force to a wheel (2010) of the vehicle, and an automatic slack adjuster (1) operatively coupled between the brake actuator and the brake mechanism, the automatic slack adjuster comprising: a lever (3, 103, 203) operatively coupled to the push rod, wherein the lever pivots about a rotational axis (R) when actuated by the push rod, the rotational axis (R) having a predetermined fixed location relative to the vehicle, wherein a stroke level of the slack adjuster (1, 101, 201) is moveable between a predetermined zero stroke position (7a, 107a, 207a) and a working stroke range (7b), and an electronic detection unit (9, 109, 209) that determines a current stroke level of the automatic slack adjuster (1, 101, 201).

13. The braking system of claim 12, wherein the electronic detection unit (9) comprises: a stroke indicator element (11) positioned on the automatic slack adjuster (1) such that the lever (3) pivots relative to the stroke indicator element (11) about the rotational axis (R) as a function of the current stroke level of the automatic slack adjuster (1), and a sensor arrangement (13) positioned on the lever (3) in the proximity of the indicator element (11), wherein the sensor arrangement (13) determines a position of the indicator element (13) relative to the sensor arrangement (9).

14. The braking system of claim 12, wherein the electronic detection unit (109) comprises: a link (119) that is pivotably coupled to the lever (103) and abuts against the push rod that is operatively coupled to the lever and that actuates lever, and a sensor arrangement (113) arranged at the lever (103), wherein the sensor arrangement (113) determines a relative angle (121) between the link (119) and the lever (103) that is indicative of a current stroke level of the automatic slack adjuster (101).

15. The braking system of claim 12, wherein the electronic detection unit (209) comprises: a first link (231) that is pivotably coupled to the lever (203) and a second link (229) that is pivotably coupled to the push rod that is operatively coupled to the lever and that actuates the lever, wherein the first link (231) and the second link (229) are coupled to one another by way of a slot guide (233) such that the first and second links (231, 229) slide relative to one another as a function of the current stroke level of the automatic slack adjuster (201), and a sensor arrangement (213) that determines a relative position of the first link (231) to the second link (229) at the slot guide (233).

16. A wheelset (2000) of an automotive vehicle, in particular of a commercial vehicle, comprising an axle or swingarm (2030), a wheel (2010) rotatably mounted to the axle or swingarm, a brake actuator (1010) fixedly mounted to the axle or swingarm and having a push rod, a brake mechanism (1070) fixedly mounted to the axle or swingarm and operatively coupled to the brake actuator (1010), wherein the brake mechanism applies a braking force to the wheel, and an automatic slack adjuster (1) operatively coupled between the brake actuator (1010) and the brake mechanism (1070), the automatic slack adjuster comprising: a lever (3, 103, 203) operatively coupled to the push rod, wherein the lever pivots about a rotational axis (R) when actuated by the push rod, the rotational axis (R) having a predetermined fixed location relative to the vehicle, wherein a stroke level of the slack adjuster (1, 101, 201) is moveable between a predetermined zero stroke position (7a, 107a, 207a) and a working stroke range (7b), and an electronic detection unit (9, 109, 209) that determines a current stroke level of the automatic slack adjuster (1, 101, 201).

17. The wheelset of claim 16, wherein the electronic detection unit (9) comprises: a stroke indicator element (11) positioned on the automatic slack adjuster (1) such that the lever (3) pivots relative to the stroke indicator element (11) about the rotational axis (R) as a function of the current stroke level of the automatic slack adjuster (1), and a sensor arrangement (13) positioned on the lever (3) in the proximity of the indicator element (11), wherein the sensor arrangement (13) determines a position of the indicator element (13) relative to the sensor arrangement (9).

18. The wheelset of claim 16, wherein the electronic detection unit (109) comprises: a link (119) that is pivotably coupled to the lever (103) and abuts against the push rod that is operatively coupled to the lever and that actuates lever, and a sensor arrangement (113) arranged at the lever (103), wherein the sensor arrangement (113) determines a relative angle (121) between the link (119) and the lever (103) that is indicative of a current stroke level of the automatic slack adjuster (101).

19. The wheelset of claim 16, wherein the electronic detection unit (209) comprises: a first link (231) that is pivotably coupled to the lever (203) and a second link (229) that is pivotably coupled to the push rod that is operatively coupled to the lever and that actuates the lever, wherein the first link (231) and the second link (229) are coupled to one another by way of a slot guide (233) such that the first and second links (231, 229) slide relative to one another as a function of the current stroke level of the automatic slack adjuster (201), and a sensor arrangement (213) that determines a relative position of the first link (231) to the second link (229) at the slot guide (233).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The invention will now be described with reference to the accompanying drawings which illustrate, one of several possible embodiments of the automatic slack adjuster proposed herein by way of example and not by way of limitation, and wherein:

[0026] FIG. 1 is an isometric view of an automatic slack adjuster according an aspect of the present disclosure;

[0027] FIG. 2 is a front view of an automatic slack adjuster illustrating another aspect of the present disclosure;

[0028] FIG. 3 is a front view of an automatic slack adjuster illustrating another aspect of the present disclosure; and

[0029] FIG. 4 is an isometric view of the automatic slack adjuster of FIG. 1 installed on a wheelset of a vehicle.

DETAILED DESCRIPTION

[0030] FIG. 1 depicts an automatic slack adjuster 1. The automatic slack adjuster 1 includes a lever 3. The lever 3 is configured to be operatively coupled to a push rod (not shown) of a brake actuator. The lever 3 pivots about a rotational axis R and is actuated by the push rod. The rotational axis R has a predetermined fixed location relative to a vehicle (not shown). The stroke level of the slack adjuster 1 is adjustable between a predetermined zero stroke position 7a and a working stroke range 7b. The automatic slack adjuster 1 comprises an electronic detection unit 9. The electronic detection unit 9 is configured for determining the current stroke level of the automatic slack adjuster 1.

[0031] The electronic detection unit 9 includes a stroke indicator element 11. The stroke indicator element 11 is positioned on the automatic slack adjuster 1 such that the lever 3 pivots relative to the stroke indicator element 11 about the rotational axis R as a function of the current stroke level of the automatic slack adjuster 1. The electronic detection unit 9 further includes a sensor arrangement 13. The sensor arrangement 13 is positioned on the lever 3 in the proximity of the indicator 11. The sensor arrangement 13 is configured to determine the relative position of the indicator element 11 to the sensor arrangement 13. The sensor arrangement 13 comprises an inductive sensor, a capacitance sensor, or a hall sensor. The stroke indicator element 11 further includes a mounting piece 15. The mounting piece 15 is configured to attach the stroke indicator element 11 in a fixed location to the vehicle. The automatic slack adjuster 1 further includes a slack adjuster mechanism 4. The lever 3 includes a mounting interface 5 for coupling the lever 3 to the push rod (not shown).

[0032] FIG. 2 shows an alternative embodiment of an automatic slack adjuster 101. The automatic slack adjuster 101 includes a lever 103 that is configured to be operatively coupled to a push rod 117 via a mounting interface 105. The automatic slack adjuster 101 further includes an electronic detection unit 109. The electronic detection unit 109 is configured for determining the current stroke level of the automatic slack adjuster 101. In this embodiment, electronic detection unit 109 comprises a link 119. The link 119 is pivotably coupled to the lever 103. The link 119 furthermore abuts against the push rod 117. The electronic detection unit 109 further includes a sensor arrangement 113. The sensor arrangement 113 is arranged at the lever 103. The sensor arrangement 113 is configured to determine a relative angle 121 between the link 119 and the lever 103. The relative angle 121 is indicative of the current stroke level of the automatic slack adjuster 101. The automatic slack adjuster 101 further includes a slack adjuster mechanism 104. The automatic slack adjuster 101 is shown in a zero stroke position 107a in FIG. 2. The automatic slack adjuster 101 is attached to the vehicle via a mounting piece 115.

[0033] The sensor arrangement 113 comprises an angular sensor 123. The angular sensor 123 is configured for determining the relative angle 121 between the link 119 and the lever 103. The link 119 comprises a spring element 125. The spring element 125 is configured to force the link 119 against the push rod 117. The spring element 125 is configured as or comprises a torsion spring 127.

[0034] A further alternative embodiment of an automatic slack adjuster 201 is shown in FIG. 3. As already explained with regard to the previous figures, the automatic slack adjuster 201 comprises a lever 203 and a slack adjuster mechanism 204. The lever 203 is connected to a push rod 217 via a mounting interface 205. The automatic slack adjuster 201 is shown in its zero stroke position 207a. The automatic slack adjuster 201 is attached to the vehicle via a mounting piece 215. In this embodiment, electronic detection unit 209 comprises a first link 231 and a second link 229. The first link 231 is pivotably coupled to the lever 203. The second linked 231 is pivotably coupled to the push rod 217. The first link 231 and the second link 229 are coupled to one another by means of a slot guide 233. In this way, the first link 231 and the second link 229 slide relative to one another as a function of the current stroke level of the automatic slack adjuster 201. The electronic detection unit 209 further includes a sensor arrangement 213. The sensor arrangement 213 is configured to determine a relative position of the first link 231 to the second link 229 at the slot guide 233. The sensor arrangement 213 is positioned at the second link 229. Furthermore, as can be seen with reference to FIG. 1-3, the rotational axis R is oriented coaxially to a rotating brake shaft of the braking system.

[0035] In operation, the automatic slack adjuster 1 (and 1′) is mounted to a wheelset 2000 of a vehicle as is shown exemplarily in FIG. 4. The wheelset 2000 includes a braking system 1000 which has a brake actuator 1010 that is configured to actuate a push rod 1030. The push rod 1030 is operatively coupled to the mounting interface 5 of the lever 3 of the automatic slack adjuster 1. The automatic slack adjuster 1 is mounted to a support element 2070 which in the present embodiment is connected to an axle 2030 of the wheelset 2000, just like the brake actuator 1010 is mounted to a corresponding support element 2050 which in turn is connected to the axle 2030.

[0036] The automatic slack adjuster 1 furthermore is coupled to a cam shaft 1050 which transmits the pivoting movement of the slack adjuster 1 to a brake mechanism 1070, for example a drum brake. The brake mechanism 1070 is configured to brake a wheel 2010 of the wheelset 2000.

[0037] The wheelset 2000 shown in FIG. 4 additionally comprises a second wheel 2010′ which is braked by a second braking system 1000′. The second braking system 1000′ is identical in setup as compared to the first braking system 1000, and identical elements are designated with identical reference signs plus an apostrophe.

[0038] Thus, the braking system 1000′ comprises a brake actuator 1010′ that is mounted to a support element 2050′ of the wheelset 2000. The brake actuator 1010′ actuates and comprises a push rod 1030′ which is operatively coupled to a further automatic slack adjuster 1′ that is held to a support element 2070′ connected to the axle 2030.

[0039] The automatic slack adjuster 1′ is operatively coupled to a further brake 1070′, such as a drum brake, by a cam shaft 1050′.

[0040] The embodiments illustrated and described herein above exemplify that the design and installation routine for an automatic slack adjuster having an indicator function is greatly simplified without sacrificing in any way the functionality regarding the read-out of the indicated stroke level.

LIST OF REFERENCE SIGNS

[0041] 1 automatic slack adjuster [0042] 3 lever [0043] 4 slack adjuster mechanism [0044] 5 mounting interface [0045] 7a zero stroke position [0046] 7b working stroke range [0047] 9 electronic detection unit [0048] 11 stroke indicator element [0049] 13 sensor arrangement [0050] 15 mounting piece [0051] 101 automatic slack adjuster [0052] 103 lever [0053] 104 slack adjuster mechanism [0054] 105 mounting interface [0055] 107a zero stroke position [0056] 109 electronic detection unit [0057] 113 sensor arrangement [0058] 115 mounting piece [0059] 117 push rod [0060] 119 link [0061] 121 relative angle between link and lever [0062] 123 angular sensor [0063] 125 spring element [0064] 127 torsion spring [0065] 201 automatic slack adjuster [0066] 203 lever [0067] 204 slack adjuster mechanism [0068] 205 mounting interface [0069] 207a zero stroke position [0070] 209 electronic detection unit [0071] 213 sensor arrangement [0072] 215 mounting piece [0073] 217 push rod [0074] 229 second link [0075] 231 first link [0076] 233 slot guide [0077] 1000 braking system [0078] 1010 brake actuator [0079] 1010′ brake actuator [0080] 1030 push rod [0081] 1030′ push rod [0082] 1050 cam shaft [0083] 1050′ cam shaft [0084] 1070 brake mechanism [0085] 1070′ brake mechanism [0086] 2000 wheelset [0087] 2010 wheel [0088] 2010′ wheel [0089] 2030 axle [0090] 2050 support element [0091] 2050′ support element [0092] 2070 support element [0093] 2070′ support element [0094] R rotational axis