SPRING BRAKE ACTUATOR AND RETAINING DEVICE FOR SUCH SPRING BRAKE ACTUATOR

Abstract

A spring brake actuator (2) for use in a commercial vehicle includes a cylinder housing (4) including a spring brake piston (10) for applying a braking force, a spring guide (12) attached to the spring brake piston (10). The spring guide (12) includes a valve (14) and a retaining device (16) for retaining the valve (14). The retaining device (16) includes a basic body (34) and clamping portions (36) for clamping the retaining device (16) to the spring guide (12). The clamping portions (36) are arranged at the basic body (34) along a circumference (38) thereof, and the clamping portions (36) are spaced apart from each other forming slits (40) between the clamping portions (36) to allow for a circulation of air through the slits (40).

Claims

1. A spring brake actuator (2), in particular a parking or emergency spring brake actuator (2) for use in a commercial vehicle, said actuator (2) comprising: a cylinder housing (4) including a cylinder housing base (6), a spring brake piston (10) located in said cylinder housing (4) for applying a braking force, a spring guide (12) attached to the spring brake piston (10), a compression spring (8) located between the cylinder housing base (6) and the spring guide (12) of the spring brake piston (10), said compression spring (8) operable to push the spring brake piston (10) away from the base (6), wherein the spring guide (12) includes a valve (14) and a retaining device (16) for retaining the valve (14), the retaining device (16) including a basic body (34) and clamping portions (36) for clamping the retaining device (16) to the spring guide (12), wherein the clamping portions (36) are arranged at the basic body (34) and along a circumference (38) of the basic body (34), wherein the clamping portions (36) are spaced apart from each other forming slits (40) between the clamping portions (36) to allow for a circulation of air through the slits (40).

2. The spring brake actuator (2) according to claim 1, wherein the basic body (34) has a disc shape.

3. The spring brake actuator (2) according to claim 1, wherein the retaining device (16) includes a circular groove (50) arranged circumferentially around a longitudinal axis (42) of the basic body (34).

4. The spring brake actuator (2) according to claim 3, wherein the circular groove (50) is V-shaped (52).

5. The spring brake actuator (2) according to claim 3, wherein the retaining device (16) has a first side (44) and a second side (46), the second side (46) arranged axially opposite the first side (44), wherein the circular groove (50) is arranged only at the first side (44).

6. The spring brake actuator (2) according to claim 1, wherein the clamping portions (36) extend diagonally outwards from the basic body (34) at an angle (54) of 1°-60° relative to the longitudinal axis (42).

7. The spring brake actuator (2) according to claim 1, wherein the clamping portions (36) are integrally formed with the basic body (34).

8. The spring brake actuator (2) according to claim 1, wherein the basic body (34) comprises 5-20 clamping portions (36).

9. The spring brake actuator (2) according to claim 1, wherein the slits (40) between the spaced apart clamping portions (36) have a width (w.sub.s) of 0.3-2 mm.

10. The spring brake actuator (2) according to claim 1, wherein the basic body has a thickness (t.sub.b) of 0.5-2 mm.

11. The spring brake actuator (2) according to claim 1, wherein the clamping portions (36) define a circular shoulder (48) for positioning the retaining device (16) in the spring guide (12).

12. The spring brake actuator (2) according to claim 1, wherein the retaining device (16) is partially or completely made of sheet metal and/or plastic, wherein the sheet metal is steel or aluminum sheet metal, wherein the plastic is one or more of crystalline or semi crystalline plastic, polypropylene terephtalate (PPT), polyamide (PA), polyoxymethylene (POM), polyphthalamide (PPA), or polypropylene (PP).

13. A retaining device (16) for retaining a valve (14), the retaining device (16) comprising: a basic body (34) and clamping portions (36) for clamping the retaining device (16) to a spring guide (12), wherein the clamping portions (36) are arranged at the basic body (34) and along a circumference (38) of the basic body (34), wherein the clamping portions (36) are spaced apart from each other forming slits (40) between the clamping portions (36) to allow for a circulation of air through the slits (40).

14. The retaining device (16) according to claim 13, wherein the retaining device (16) includes a circular groove (50) arranged circumferentially around a longitudinal axis (42) of the basic body (34).

15. The retaining device (16) according to claim 14, wherein the circular groove (50) is V-shaped (52).

16. The retaining device (16) according to claim 14, wherein the retaining device (16) has a first side (44) and a second side (46), the second side (46) arranged axially opposite of the first side (44), wherein the circular groove (50) is arranged only at the first side (44).

17. The retaining device (16) according to claim 13, wherein the clamping portions (36) extend diagonally outwards from the basic body (34) at an angle (54) of 1°-60° relative to the longitudinal axis (42).

18. The retaining device (16) according to claim 13, wherein the clamping portions (36) are integrally formed with the basic body (34).

19. The retaining device (16) according to claim 3, wherein the clamping portions (36) define a circular shoulder (48) for positioning the retaining device (16) against a corresponding circular shoulder defined in the spring guide (12).

20. The spring brake actuator (2) according to claim 11, wherein the spring guide (12) defines a receiving space (30) having a receiving space shoulder (32) abutting the circular shoulder (48) of the retaining device (16) disposed within the receiving space (30).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] This present disclosure will now be described with reference to the accompanying drawings which illustrate, by way of example and not by way of limitation, one of several possible embodiments of the brake actuator proposed herein, and wherein:

[0026] FIG. 1 is a sectional view of a spring brake actuator according to an aspect of the disclosure;

[0027] FIG. 2 is an enlarged sectional view of the spring brake actuator according to FIG. 1 showing a retaining device according to an aspect of the disclosure;

[0028] FIG. 3 is a perspective view of one side of the retaining device according to an aspect of the disclosure;

[0029] FIG. 4 is a perspective view of another side of the retaining according to an aspect of the disclosure; and

[0030] FIG. 5 is a sectional view of the retaining device according to an aspect of the disclosure.

DETAILED DESCRIPTION

[0031] FIG. 1 shows a cross-sectional schematic view of a spring brake actuator 2. The spring brake actuator 2 includes a cylinder housing 4. Inside the cylinder housing 4, a compression spring 8 and a pressure chamber 23 are arranged. The compression spring 8 rests on the left side of FIG. 1 against a cylinder housing base 6 and on the opposite side on a spring guide 12 of a spring brake piston 10. The spring brake piston 10 is shown being held in a brake release position by a positive pressure inside the pressure chamber 23.

[0032] The spring brake piston 10 is adapted to act upon a diaphragm 24 of the spring brake actuator 2, which transmits the inflicted force to a rod 26 which, in turn, transmits the applied power to the wheel brakes (not shown).

[0033] The spring brake actuator 2 furthermore includes a release bolt 29. The release bolt 29 is utilized to release the spring brake actuator 2 in case of malfunctions, for example. The spring brake actuator 2 moreover includes a flange 18 which is utilized to connect a service brake 27 to the spring brake actuator 2. The service brake 27 includes a service brake pressure chamber 25 into which a pressure may be built up to generate a force upon the service diaphragm 28 which transmits the inflicted force to the rod 26.

[0034] In the event that both the spring brake actuator 2 and the service brake 27 are operated simultaneously, pressure is released from the service brake pressure chamber 25 through an internal breathing valve 20 and via a tubular stem 22 through a retaining device 16 and a check valve 14 into the pressure chamber 23. With the help of this arrangement, whenever the spring brake actuator 2 and the service brake 27 are operated simultaneously (which is also called compounding), the braking forces of the two brakes do not add up and damage the rod 26 or parts of the wheel brakes.

[0035] FIG. 2 shows a detailed view of a portion of the spring brake actuator 2 having the retaining device 16. As can be seen from FIG. 2, the retaining device 16 retains the check valve 14 and attaches it to the spring guide 12. The retaining device 16 holds the check valve 14 in place and also allows for a passage of air through the retaining device 16. The retaining device 16 is attached in a receiving space 30 and held in position with the help of a receiving space shoulder 32.

[0036] FIG. 3 shows a detailed perspective of the retaining device 16. The retaining device 16 comprises a basic body 34 and clamping portions 36. The clamping portions 36 are arranged along a circumference 38 of the basic body 34. The clamping portions 36 are spaced apart from each other forming slits 40 in between the clamping portions 36 to allow for a circulation of air through the slits 40. The slits have a width w.sub.s. In FIG. 3, a first side 44 of the basic body 34 is shown. Furthermore, a longitudinal axis 42 of the retaining device 16 is illustrated. The basic body 34 illustrated in FIG. 3 includes eight clamping portions 36. Also, the retaining device 16 includes a circular groove 50 arranged circumferentially around the longitudinal axis 42. The groove 50 facilitates the capability of the clamping portions 36 to be bendable inwardly towards the longitudinal axis 42 to allow for an easy assembly of the retaining device 16.

[0037] FIG. 4 shows the retaining device 16 from another side showing a second side 46 of the basic body 34. It can be seen from FIG. 4 that the clamping portions 36 include a circular shoulder 48. This circular shoulder 48 may be brought into alignment with the receiving space shoulder 32 (see FIG. 2) to center and accommodate the retaining device 16 in the desired position.

[0038] FIG. 5 shows a cross-sectional view of the retaining device 16 including the basic body 34 and clamping portions 36. The retaining device 16 includes the circular groove 50 arranged circumferentially around the longitudinal axis 42 of the basic body 34. The circular groove 50 is V-shaped 52. Furthermore, the circular groove 50 is arranged at the first side 44 of the basic body 34, only. The basic body 34 has a thickness t.sub.b while the clamping portions 36 extend diagonally outwards from the basic body 34 at an angle 54.

[0039] The above detailed description illustrates and describes what is considered as a preferred embodiment of the invention. It should of course be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the present disclosure. It is therefore intended that the present disclosure may not be limited to the exact form and detail shown and described herein, nor to anything less than the whole of the present disclosure disclosed herein and as claimed hereinafter. Further, the features described in the description, the drawings, and the claims disclosing the invention may be essential for the invention considered alone or in combination. In particular, any reference signs in the claims shall not be construed as limiting the scope of the invention. The wording “comprising” does not exclude other elements or steps. The wording “a” or “an” does not exclude a plurality.

LIST OF REFERENCES (PART OF SPECIFICATION)

[0040] 2 spring brake actuator

[0041] 4 cylinder housing

[0042] 6 cylinder housing base

[0043] 8 compression spring

[0044] 10 spring brake piston

[0045] 12 spring guide

[0046] 14 check valve

[0047] 16 retaining device

[0048] 18 flange

[0049] 20 internal breathing valve

[0050] 22 tubular stem

[0051] 23 pressure chamber

[0052] 24 diaphragm

[0053] 25 service brake pressure chamber

[0054] 26 rod

[0055] 27 service brake

[0056] 28 service diaphragm

[0057] 29 release bolt

[0058] 30 receiving space

[0059] 32 receiving space shoulder

[0060] 34 basic body

[0061] 36 clamping portions

[0062] 38 circumference of the basic body

[0063] 40 slits

[0064] 42 longitudinal axis

[0065] 44 first side of basic body

[0066] 46 second side of basic body

[0067] 48 circular shoulder

[0068] 50 circular groove

[0069] 52 V-shape

[0070] 54 clamping portions extending angle

[0071] w.sub.s width of slits

[0072] t.sub.b thickness of basic body