Brake system damping device

Abstract

A brake system damping device includes a first chamber on which hydraulic pressure is to be applied, a second chamber with a compressible medium located therein, and a first separating element configured to separate the first and second chambers. The damping device further includes a third chamber with a compressible medium located therein and a second separating element configured to separate the second and third chambers. The second and third chambers are connected in a medium-conducting manner via a passage in the second separating element. The first separating element is configured to move a closure element to close the passage when the hydraulic pressure in the first chamber has reached a predefined pressure value. The first and second separating elements form an assembly in which the first and second separating elements extend along an axis and the first separating element is covered radially on the outside by an envelope surface.

Claims

1. A brake system damping device, comprising: a first chamber on which hydraulic pressure is to be applied; a second chamber in which a compressible medium is located; a first separating element configured to separate the first chamber from the second chamber; a third chamber in which a compressible medium is located; a second separating element configured to separate the second chamber from the third chamber, the second chamber connected to the third chamber in a medium-conducting manner by a passage configured in the second separating element; and a closure element configured to be moved with the first separating element, the passage configured to be closed by the closure element as soon as the hydraulic pressure in the first chamber has reached a predefined pressure value, wherein the first separating element and the second separating element are configured to be preassembled to form an assembly in which the first and second separating elements extend along an axis and the first separating element is covered radially on the outside at least in certain portions by an envelope surface, wherein the envelope surface is formed by a hollow cylindrical sleeve disposed on the first separating element, and wherein the hollow cylindrical sleeve has a first axial end and a second axial end, the first and second axial ends being open ends.

2. The brake system damping device as claimed in claim 1, wherein the hollow cylindrical sleeve is configured with a radially external interference fit configured to press into a housing that receives the assembly.

3. The brake system damping device as claimed in claim 1, wherein the hollow cylindrical sleeve is configured with a radially internal first insertion bevel configured to facilitate pushing of the envelope surface onto the first separating element.

4. The brake system damping device as claimed in claim 1, wherein the hollow cylindrical sleeve is configured with a radially external second insertion bevel configured to facilitate insertion of the hollow cylindrical sleeve into a housing that receives the assembly.

5. The brake system damping device as claimed in claim 1, wherein the hollow cylindrical sleeve is configured with a radially external shoulder configured for support on a housing that receives the assembly.

6. The brake system damping device as claimed in claim 1, wherein the second separating element is supported by a cover that simultaneously delimits the third chamber.

7. The brake system damping device as claimed in claim 6, wherein the second separating element is fully enclosed by the cover and the first separating element.

8. The brake system damping device as claimed in claim 1, wherein the first separating element has an annular sealing bead that bears in a sealing manner against the second separating element.

9. The brake system damping device as claimed in claim 8, wherein the annular sealing bead bears against a cover that supports the second separating element.

10. The brake system damping device as claimed in claim 1, wherein the first separating element is formed in one piece with the closure element.

11. The brake system damping device as claimed in claim 1, wherein the first separating element is configured with a diaphragm.

12. The brake system damping device as claimed in claim 1, wherein the first separating element is produced from an elastomer.

13. The brake system damping device as claimed in claim 12, wherein the elastomer is ethylene propylene diene rubber.

14. The brake system damping device as claimed in claim 1, wherein the hollow cylindrical sleeve is pushed onto the first separating element to form the envelope surface.

15. The brake system damping device as claimed in claim 1, further comprising: a cover that supports the second separating element and delimits the third chamber, wherein the first axial end includes a shoulder projecting radially outwardly, the shoulder having a first axial surface that engages the cover.

16. The brake system damping device as claimed in claim 15, wherein the assembly is received in a housing, and the shoulder has a second axial surface that is supported on the housing.

17. The brake system damping device as claimed in claim 16, wherein the first axial end has a first insertion bevel on a radially internal side of the hollow cylindrical sleeve that is configured to facilitate pushing of the envelope surface onto the first separating element, and the second axial end has a second insertion bevel on a radially external side of the hollow cylindrical sleeve that is configured to facilitate insertion of the envelope surface into the housing.

18. The brake system damping device as claimed in claim 1, further comprising: a cover that supports the second separating element and delimits the third chamber, wherein the first axial end circumferentially surrounds the cover, and the second axial end circumferentially surrounds the first separating element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the solution according to the disclosure are explained in greater detail below on the basis of the enclosed schematic drawings. In the drawings:

(2) FIG. 1 shows a first exemplary embodiment of a brake system damping device according to the disclosure,

(3) FIG. 2 shows the brake system damping device in FIG. 1 in the case of a first applied hydraulic pressure,

(4) FIG. 3 shows the brake system damping device in FIG. 1 in the case of a second applied hydraulic pressure,

(5) FIG. 4 shows a diagram with characteristic lines as a function of pressure and volume take-up in brake system damping devices and

(6) FIG. 5 shows a second exemplary embodiment of a brake system damping device according to the disclosure,

(7) FIG. 6 shows a third exemplary embodiment of a brake system damping device according to the disclosure in three first steps of its mounting,

(8) FIG. 7 shows the exemplary embodiment according to FIG. 6 in two further steps of its mounting, and

(9) FIG. 8 shows the exemplary embodiment according to FIG. 6 in two last steps of its mounting.

DETAILED DESCRIPTION

(10) A brake system damping device 10 having a housing 12 and a cover 14 is represented in FIG. 1. There is arranged in housing 12 a supply line 16, in which in the present case no hydraulic pressure is applied, represented by means of a crisscrossed arrow 18. Supply line 16 discharges into a first chamber 20 which adjoins a first separating element 22, here a roller diaphragm. As seen from first chamber 20, a second chamber 24 is located behind first separating element 22, which second chamber 24 is adjoined by a second separating element 26, wherein in the direction of view a third chamber 28 is located behind second separating element 26.

(11) As seen in detail, these chambers 20, 24, 28 and separating elements 22, 26 have the following appearance. First chamber 20 is surrounded by a housing inner wall 30 and a first separating element inner wall 32 of first separating element 22, referred to below as a roller diaphragm. A closure element 34 from which separating element 22 extends further to the outside to a diaphragm fold 36 is arranged to be formed centrally in separating element 22 and formed in one piece with it. A diaphragm fold recess 38 is located within diaphragm fold 36 or is surrounded by it. Adjoining diaphragm fold 36, separating element 22 extends up to a diaphragm collar 40 which engages around a coupling rim 42 of housing 12. Separating element 22 configured as a roller diaphragm bears with a part of its separating element inner wall 32 in a sealing manner against housing inner wall 30, and faces toward second chamber 24 with a first separating element outer wall 44. Second chamber 24 is surrounded by first separating element outer wall 44 and a second separating element inner wall 46 of second separating element 26.

(12) Second separating element 26 extends with a diaphragm retaining apparatus 48 into diaphragm fold recess 38. A passage 50 which connects second chamber 24 to third chamber 28 is arranged centrally in second separating element 26. Passage 50 is guided through second separating element inner wall 46, second separating element 26 and a second separating element outer wall 52. Third chamber 28 is surrounded by second separating element outer wall 52 and a cover inner wall 54 of cover 14.

(13) In the represented starting state of brake system damping device 10, no hydraulic pressure is initially applied in first chamber 20 in which a brake medium is located. Separating element 22, which is produced from an elastomer, is therefore located here substantially in its basic form. In this case, it bears against housing inner wall 30 in such a manner that first chamber 20 is hermetically sealed off from second chamber 24, wherein a gas, here specifically air, is located in second chamber 24. This gas is also located in third chamber 28 which is connected to second chamber 24 by means of passage 50. Both chambers 24, 28 thus form a joint gas volume available for damping. As a result of the greater elasticity of this gas volume, a better damping action is achieved during braking or when applying a hydraulic pressure on first chamber 20.

(14) If a hydraulic pressure is applied in first chamber 20, separating element 22 deforms in such a manner that the gas volume in second chamber 24 is reduced. Closure element 34 moves into second chamber 24. From a specific hydraulic pressure which is set above a pressure range which is relevant for damping, closure element 34 bears against second separating element inner wall 46 of second separating element 26 and closes passage 50 to third chamber 28. Second separating element 26 acts like a stop here. States of brake system damping device 10, in the case of which separating element 22 or closure element 34 thereof against second separating element 26 and closes passage 50, are represented in FIG. 2 and FIG. 3.

(15) As a result of closed passage 50, third chamber 28 is thus separated from second chamber 24, as a result of which only the remaining gas volume in second chamber 24 can be used for the further damping. The elasticity and damping action is only small since second chamber 24 is barely able to take up further volume. This effect is intentional since the travel of a brake pedal connected to the brake system is thus also no longer significantly lengthened. In the case of the state represented in FIG. 3 of brake system damping device 10, separating element 22 and second separating element 26 bear seamlessly or across the full surface against one another so that second chamber 24 disappears entirely or has no volume any more. In this case, the travel of the brake pedal is no longer lengthened.

(16) As soon as the hydraulic pressure applied in first chamber 20 decreases, separating element 22 moves back into its starting state or its starting position.

(17) FIG. 2 shows brake system damping device 10 from FIG. 1, but in a state in the case of which a first hydraulic pressure is applied on first chamber 20, represented by means of an arrow 56 in the region of supply line 16.

(18) As already mentioned, closure element 34 bears against second separating element inner wall 46 of second separating element 26 and closes passage 50 to third chamber 28. Only the remaining volume in second chamber 24 can thus be used for the further damping. In the representation of FIG. 2, this is primarily the region around diaphragm retaining apparatus 48. The effects on the damping and the braking process have already been listed in detail in the description relating to FIG. 1 and are therefore not described again here.

(19) FIG. 3 represents brake system damping device 10 from FIG. 1, but in a state in which a second hydraulic pressure is applied on first chamber 20, represented by means of an arrow 58 in the region of supply line 16.

(20) As already mentioned, closure element 34 bears against second separating element inner wall 46 of second separating element 26 and closes passage 50 to third chamber 28. Separating element 22 and second separating element 26 furthermore bear seamlessly against one another so that second chamber 24 no longer has any volume. The effects associated with this on damping and the braking process have already been listed in detail in the description in relation to FIG. 1 and are therefore not described again here.

(21) FIG. 4 shows a diagram of the relationship between a pressure 60 and a volume take-up 62 in such brake system damping devices. Here, pressure 60 is plotted on the x-axis and volume take-up 62 is plotted on the y-axis. A first characteristic line 64 and a second characteristic line 66 extend from a coordinate origin of the diagram. The diagram also shows a vertical, dashed line 68 which intersects the x-axis and a horizontal, dashed line 70 which intersects the y-axis.

(22) First characteristic line 64 shows the relationship between pressure and volume take-up for a brake system damping device with a small volume of medium which is available for damping. For the sake of simplicity here, the volume of second chamber 24 in FIG. 1 is assumed for said characteristic line 64.

(23) Second characteristic line 66 which extends above first characteristic line 64 shows the relationship between pressure and volume take-up for a brake system damping device with a comparatively large volume of medium which is available for damping. For the sake of simplicity, the total volume of second and third chamber 24, 28 in FIG. 1 is assumed here for characteristic line 66.

(24) A predefined pressure value 68 which forms the upper limit of a pressure range which is relevant for pulsation damping in such brake systems is represented with vertical, dashed line which intersects the x-axis. This relevant pressure region thus extends from the coordinate origin up to the dashed line.

(25) A volume stop 70 for brake system damping device 10 according to the disclosure is represented with the horizontal, dashed line which intersects the y-axis. This volume stop lies approximately at the volume of second chamber 24 in FIG. 1.

(26) By means of corresponding configuration of the respective volumes of second and third chamber 24, 28, brake system damping device 10 is matched to the relevant pressure range and the desired elasticity or damping action in this pressure range. In the case of optimum matching, as represented in the diagram of FIG. 4, dashed lines 68, 70 intersect with characteristic line 66 at a point.

(27) FIG. 5 represents a brake system damping device 10 which differs from that in FIG. 1 only in the region in which first separating wall 22 configured as a roller diaphragm faces with first separating element outer wall 44. Separating element 22 itself and the region which separating element 22 faces with first separating element inner wall 32 correspond entirely with FIG. 1, and are not described again here.

(28) The main difference from brake system damping device 10 in FIG. 1 is that, instead of third chamber 28 and associated passage 50 in FIG. 1, brake system damping device 10 here in FIG. 5 has a first sub-chamber 72 with a passage 74 and a second sub-chamber 76 with a second passage 78. The two sub-chambers 72, 76 are separated by means of a separating wall 80. A further difference to FIG. 1 lies in second separating element 26 extending up to housing inner wall 30 here in FIG. 5 and separating cover 14 from it.

(29) All of the further features correspond to those in FIG. 1. Second chamber 24 is thus also surrounded here by first separating element outer wall 44 and a second separating element inner wall 46 of second separating element 26. Second separating element 26 also extends here with a diaphragm holding apparatus 48 into diaphragm fold recess 38 of separating element 22. Moreover, sub-chambers 72, 76 are next to separating wall 80, like third chamber 28 in FIG. 1, surrounded by second separating element outer wall 52 and a cover inner wall 54 of cover 14.

(30) The mode of operation here is similar to brake system damping device 10 in FIG. 1. If a hydraulic pressure is applied in first chamber 20, separating element 22 also deforms here such that the gas volume in second chamber 24 is reduced. Closure element 34 moves into second chamber 24 and, from a specific hydraulic pressure which ideally corresponds to the upper limit of the relevant pressure region bears against second separating element 26 and closes passages 74, 78 to sub-chambers 72, 76.

(31) As soon as the hydraulic pressure applied in first chamber 20 is reduced, separating element 22 configured as a roller diaphragm moves back into its starting state or its starting position. As a result of this, passages 74, 78 are then opened again and sub-chambers 72, 76 are connected again to second chamber 24.

(32) FIGS. 6 to 8 illustrate an exemplary embodiment of a brake system damping device 10 in the case of which the second separating element 26 is likewise configured with a passage 50 and sub-chambers 72 and 76 by means of at least one separating wall 80. The second separating element 26 is furthermore configured, at its jacket outer wall 82 of the third chamber 28, such that said second separating element forms a fluid-tight interference fit 84 with the cover 14 there.

(33) In the case of the brake system damping device 10 as per FIGS. 6 to 8, it is furthermore the case that the first separating element 22 and the second separating element 26 and also the cover 14 are to be preassembled to form an assembly 86 in which the first and second separating elements 22, 26 extends along an axis 88 and the first separating element 22 is covered radially on the outside at least in certain portions by means of a hollow cylindrical sleeve 92, which is pushed onto the first separating element 22.

(34) FIG. 6 shows, on the left, the cover 14 and, in the center, the second separating element 26 pre-mounted thereon by means of the interference fit 84. Furthermore, FIG. 6 shows, on the right, the first separating element 22 pre-mounted onto the second separating element 26 and onto the cover 14. Here, the cover 14 and the first separating element 22 fully enclose the second separating element 26. It is also possible in FIG. 6 to see the two chambers 24 and 28 thus formed. Furthermore, on the first separating element 22, it is possible to see the diaphragm collar 40 thereof and also a sealing bead 94, by means of which the first separating element 22 seals radially at the outside against the second separating element 26 and axially against the cover 14.

(35) FIG. 7 shows the in this case hat-shaped sleeve 92 and the mounting thereof on the preassembled assembly 86 composed of cover 14, second separating element 26 and first separating element 22. The sleeve 92 has a substantially hollow cylindrical jacket wall 96, which extends in an axial direction, and a shoulder 98, which, to the left of said jacket wall as seen in FIG. 7, projects substantially in a radial direction. At the transition from the jacket wall 96 to the shoulder 98, there is formed a radially internal first insertion bevel 100. Said insertion bevel 100 facilitates the pushing of the sleeve 92 onto the first separating element 22 and, there, in particular onto the sealing bead 94 (see FIG. 7, left). With the pushing of the sleeve 92 onto the sealing bead 94, the latter is forced radially against the second separating element 26 and also axially against the cover 14 in order to seal in fluid-tight fashion there. The insertion bevel 100 furthermore also facilitates the further pushing of the sleeve 92 with the jacket wall 96 thereof radially at the outside onto a collar portion 102, which encompasses the second separating element 26 at its jacket outer wall 82, of the cover 14 (see FIG. 7, right). The sleeve 92 is pushed onto the assembly 86 until said sleeve comes to bear with its shoulder 98 against the cover 14.

(36) Finally, FIG. 8 illustrates how the assembly 86 is to be mounted together with the sleeve 92 into the housing 12. Here, it can be seen that the sleeve 92 is equipped, at its end region, facing toward the housing 12, of its jacket wall 96, with a radially external second insertion bevel 104, by means of which the insertion into the bulge, which forms the chamber 20, of the housing 12 is facilitated. As the assembly 86 is inserted together with the sleeve 92, the envelope surface 90 thereof simultaneously protects the first separating element 22 with its sealing bead 94 against damage owing to friction along the housing inner wall 30 (see FIG. 8, left). At the same time, a force-fitting interference fit 106, which seals in fluid-tight fashion, is formed between the envelope surface 90 and the housing inner wall 30.

(37) As the last step of the mounting, cover 14 is fixed externally on housing 12 by means of a caulking 108 and in this manner the arrangement of first separating element 22, second separating element 26, cover 14 and sleeve 92 is arranged in housing 12 in a stationary manner (see FIG. 8, right).