PNEUMATIC BRAKE ACTUATOR AND PUSHROD BOOT FOR SUCH ACTUATOR

Abstract

A rod boot (24) seals a rod opening (20), through which a piston rod of a piston of a pneumatic actuator is guided from a retained position to an extended position. The rod boot is connected to the rod opening (20) and the piston rod (18). A mantle (30) of the rod boot (24) has a first section (34) and a second section (36) opposite from the first section (34). The first section (34) is connected to the rod opening (20) and the second section (36) is connected to a mounting section (38) of the piston rod (18). The second section (36) is inverted inwardly (40) relative to the first section (34), and the longitudinal dimensions of the first section (34) and second section (36) vary relative to each other as a function of a relative position of the first section (34) to the second section (36).

Claims

1. A pneumatic brake actuator (4) for a vehicle, comprising: an actuator housing (6) having a pressure chamber (8) and a piston chamber (10), a piston (12) mounted inside the piston chamber (10) and that reciprocatingly moves between a retained position (14) and an extended position (16) as a function of pressure inside the pressure chamber (8), a piston rod (18) connected to the piston (12), wherein the piston rod (18) is guided through the actuator housing (6) via a rod opening (20), a compression spring (22) that pushes the piston (12) towards the retained position (14), and a rod boot (24) that seals the rod opening (20), wherein the rod boot (24) is connected to the rod opening (20) and the piston rod (18), the rod boot (24) including a mantle (30), the mantle (30) having a first section (34) and a second section (36) opposite from the first section (34), and wherein the first section (34) is connected to the rod opening (20) and the second section (36) is connected to a mounting section (38) of the piston rod (18), wherein the second section (36) is inverted inwardly (40) relative to the first section (34), wherein a longitudinal dimension (I.sub.1) of the first section (34) and a longitudinal dimension (I.sub.2) of the second section (36) vary with respect to each other as a function of a relative position of the first section (34) to the second section (36).

2. The brake actuator (4) according to claim 1, wherein the rod boot (24) extends out of the actuator housing (6) through the rod opening (20) when the piston (12) is in its extended position (14).

3. The brake actuator (4) according to claim 1, wherein a diameter (42) of the mantle (30) tapers from the first section (34) to the second section (36).

4. The brake actuator (4) according to claim 1, wherein the mantle (30) includes a varying thickness.

5. The brake actuator (4) according to claim 1, wherein the mantle (30) includes at least one rib (46).

6. The brake actuator (4) according to claim 5, wherein said rib (46) extends along the longitudinal axis (32).

7. The brake actuator (4) according to claim 5, wherein the mantle (30) includes four ribs (46), said ribs (46) being equidistantly spaced around said mantle (30).

8. The brake actuator (4) according to claim 5, wherein said at least one rib (46) is arranged at the inside (48) of said mantle (30).

9. The brake actuator (4) according to claim 5, wherein the mantle (30) includes at least one groove (52).

10. The brake actuator (4) according to claim 9, wherein said grove (52) is arranged at the outside (50) of said mantle (30) radially adjacent to the at least one rib (46), which is arranged on the inside of said mantle (30).

11. The brake actuator (4) according to claim 1, wherein said first section (34) includes a flange section (54) that secures said first section (34) to the rod opening (20).

12. The brake actuator (4) according to claim 11, wherein said flange section (54) includes a circumferential groove (56) that forms a seal with the rod opening (20).

13. The brake actuator (4) according to claim 11, wherein said second section (36) includes a shoulder (58) that engages with a corresponding shoulder (60) of the piston rod (18) to form a seal therewith.

14. A rod boot (24) for sealing a rod opening (20) for a pneumatic brake actuator of a vehicle, wherein said rod boot (24) is configured to be connected to a rod opening (20) and a piston rod (18), said rod boot comprising: a mantle (30), said mantle (30) having a first section (34) and a second section (36) opposite from the first section (34), and wherein the first section (36) is configured to be connected to a rod opening (20) of a pneumatic brake actuator (4) and the second section (36) is configured to be connected to a mounting section (38) of a piston rod (18) of the actuator (4), wherein the second section (36) is inverted inwardly (40) relative to the first section (34), wherein a longitudinal dimension (I.sub.1) of the first section (34) and a longitudinal dimension (I.sub.2) of the second section (36) vary with respect to each other as a function of a relative position of the first section (34) to the second section (36).

15. The rod boot (24) according to claim 14 for sealing a rod opening (20) of a pneumatic brake actuator (4) of a commercial vehicle, wherein the rod boot (24) is installed in a rod opening (20) of the pneumatic brake actuator.

16. The brake actuator according to claim 1, wherein the longitudinal dimension (I.sub.1) of the first section (34) is longer than the longitudinal dimension (I.sub.2) of the second section (36) when the piston (12) is in the retained position.

17. The brake actuator according to claim 16, wherein the longitudinal dimension (I.sub.1) of the first section (34) is shorter than the longitudinal dimension (I.sub.2) of the second section (36) when the piston (12) is in the extended position.

18. The brake actuator according to claim 2, wherein the rod boot (24) extends into a caliper box (26) from the rod opening (20) when the piston (12) is in its extended position (14).

19. The brake actuator according to claim 18, wherein the piston rod actuates a lever disposed within the caliper box when the piston (12) is in its extended position.

20. The brake actuator according to claim 1, wherein the second section (36) axially overlaps the first section (34) when the piston (12) is in the retained position, wherein the second section (36) is moveable substantially without friction relative to the first section (34) when the piston (12) moves toward the extended position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present disclosure will now be described with reference to the accompanying drawings which illustrate, by way of example and not by way of limitations, one of several possible embodiments of the spring brake actuator provided herein, and wherein:

[0024] FIG. 1 shows a preferred embodiment of pneumatic brake actuator according to the concept of the present disclosure in a sectional view, wherein the piston is in a retained position;

[0025] FIG. 2 shows the preferred embodiment of the pneumatic brake actuator according to FIG. 1, wherein the piston is in an extended position;

[0026] FIG. 3 shows a perspective view of a rod boot according to the concept of the present disclosure; and

[0027] FIG. 4 shows a perspective view of a rod boot according to the concept of the present disclosure.

DETAILED DESCRIPTION

[0028] FIG. 1 shows a vehicle braking system 2. The vehicle braking system 2 includes a pneumatic actuator 4. The pneumatic actuator 4 includes an actuator housing 6. The actuator housing 6 includes a pressure chamber 8 and a piston chamber 10. In the piston chamber 10, a piston 12 is mounted. The piston 12 is configured to reciprocatingly move between a retrained position 14 and in extended position 16 (shown in FIG. 2) as a function of pressure inside the pressure chamber 8.

[0029] A piston rod 18 is connected to piston 12. The piston rod 18 is guided through and out of the actuator housing 6 via a rod opening 20. The pneumatic brake actuator 4 moreover includes a compression spring 22. The compression spring 22 is effective to push the piston 12 towards the retained position 14. The pneumatic brake actuator 4 moreover includes a rod boot 24. The rod boot 24 is configured for sealing the rod opening 20. The rod boot 24 is connected to the rod opening 20 and the piston rod 18.

[0030] The rod boot 24 includes a mantle 30. The mantle 30 has a first section 34 and a second section 36. The second section 36 is opposite from the first section 34. The first section 34 is connected to the rod opening 20. The second section 36 is connected to a mounting section 38 of the piston rod 18. The second section 36 of the rod boot 24 is inverted inwardly 14 relative to the first section 34. A longitudinal dimension I.sub.1 of the first section 34 and a longitudinal dimension I.sub.2 of the second section 36 vary with respect to each other as a function of a relative position of the first section 34 to the second section 36. The braking system 2 moreover includes a caliper box 26. In the caliper box 26 a lever 28 is arranged.

[0031] FIG. 2 shows the actuator of FIG. 1 in an extended position 16. It can be seen that the rod boot 24 now extends out of the actuator housing 6 through the rod opening 20 and into the caliper box 26. The volume that is now occupied by the rod boot 24 inside the actuator housing 6 is minimal.

[0032] FIGS. 3 and 4 show perspective views of the rod boot 24 in perspective views. The rod boot includes the mantle 30. The diameter 42 of the mantle 30 tapers from the first section 34 to the second section 36. Furthermore, the mantle 30 includes a varying thickness. The mantle includes four ribs 46. The ribs 46 extend along a longitudinal axis 32. The ribs 46 are equidistantly spaced around the mantle 30. The ribs 46 are arranged at the inside 48 of the mantle 30. Furthermore, the mantle includes grooves 52. The grooves 52 are arranged at the outside 50 of the mantle 30. The grooves 52 are arranged adjacent to the ribs 46. The mantle 30 includes four grooves 52. A rib 46 at the inside 48 of the mantle 30 forms a groove 52 at the outside 50 of the mantle 30. The mantle 30 has a thickness 44.

[0033] Furthermore, the first section 34 includes a flange section 54. The flange section 54 is configured for securing said first section 34 to the rod opening 20. The flange section 54 includes a circumferential groove 56. The circumferential groove 56 is configured to form a seal with the rod opening 20. The second section 36 includes a shoulder 58. The shoulder 58 is configured for engaging with a corresponding shoulder 60 (see FIGS. 1 and 2) of the piston rod 18, to form a seal therewith.

LIST OF REFERENCE SIGNS (PART OF THE DESCRIPTION)

[0034] 2 braking system [0035] 4 pneumatic brake actuator [0036] 6 actuator housing [0037] 8 pressure chamber [0038] 10 piston chamber [0039] 12 piston [0040] 14 retained position [0041] 16 extended position [0042] 18 piston rod [0043] 20 rod opening [0044] 22 compression spring [0045] 24 rod boot [0046] 26 caliper box [0047] 28 lever [0048] 30 mantle [0049] 32 longitudinal axis [0050] 34 first section [0051] 36 second section [0052] 38 mounting section [0053] 40 inward inversion [0054] 42 mantle diameter [0055] 44 mantle thickness [0056] 46 rib [0057] 48 mantle inside [0058] 50 mantle outside [0059] 52 mantle groove [0060] 54 flange section [0061] 56 circumferential groove [0062] 58 mantle shoulder [0063] 60 rod shoulder