Throttle device for a pressure damper

Abstract

The invention relates to a throttle device (9) for a pressure damper (1) of a hydraulic brake system of a motor vehicle, comprising a cover element (10) which can be secured to a housing (2) of the pressure damper (1) in the region of an outlet opening (4) of the pressure damper (1) and which has a base (24) and a casing wall (11) protruding from the base (24) and at least substantially closed in the circumferential direction, wherein the base (24) has, on its end face (14) facing the casing wall (11), at least one recess (13) which extends at least substantially radially and opens into an opening (12) in the casing wall (11). According to the invention, the recess (13) and the opening (12) are formed by an at least substantially radially oriented bore (19).

Description

[0001] R. 415016

[0002] - 1 -

[0003] Description

[0004] The present invention relates to a throttling device for a pressure damper of a hydraulic brake system of a motor vehicle, comprising a cover element which can be attached to a housing of the pressure damper in the area of ​​an outlet opening of the pressure damper and which has a base and a shell wall projecting from the base and being at least substantially closed in the circumferential direction, wherein the base has at least one recess extending at least substantially radially on its end face facing the shell wall, which opens into an opening in the shell wall.

[0005] The invention further relates to a hydraulic pressure damper for a hydraulic brake system of a motor vehicle, with a housing having an inlet opening and an outlet opening, wherein a valve body for closing the inlet opening is assigned to the inlet opening, wherein a throttle device is assigned to the outlet opening, and wherein a spring element is held pre-tensioned between the throttle device and the valve body.

[0006] State of the art

[0007] Throttle devices of the type mentioned above are already known from the prior art. Modern motor vehicle braking systems have additional functions that support the driver, particularly with regard to safety. For example, such braking systems actively intervene in braking operation to generate or reduce braking force without requiring any input from the driver. R. 415016

[0008] - 2 - must act independently. Often, a controllable pumping module, such as a piston pump, is activated to provide hydraulic pressure in the brake system independently of accelerator pedal operation. However, the operation of the pumping device can generate noise that impairs the comfort of the driver or passenger. To prevent this, hydraulic pressure dampers are used to reduce or prevent unwanted pressure pulsations in the hydraulic brake system.

[0009] A known pressure damper, for example, has a housing with an inlet and an outlet. A brake circuit is assigned to the inlet to be pressurized by the pressure present in the brake circuit. A movable valve element is also assigned to the inlet, which counteracts the hydraulic pressure. For this purpose, the valve element is pre-tensioned in its closed position by a spring element. The outlet is assigned to a throttling device that defines the hydraulic resistance of the pressure damper. The throttling device is formed by a cover that closes the outlet and has a recess extending transversely across the end face facing the outlet, which is produced by cold forging.The recess, together with the outlet opening, forms an outflow path for the hydraulic medium, which, by opening the valve element, passes it and reaches the outlet opening, whereby the flow cross-section of the recess, which leads to the opening in the casing wall and through which the hydraulic medium can flow, defines the resistance of the throttling device.

[0010] Disclosure of the invention

[0011] The throttling device according to the invention, with the features of claim 1, has the advantage that the outflow path through the throttling device can be manufactured cost-effectively and with less effort. According to the invention, the recess and the opening are formed by a bore that is at least substantially radially oriented. The recess is thus formed neither by cold forging nor by complex machining. R. 415016

[0012] - 3 - is not produced, but rather by a simple radial bore or at least substantially radially oriented bores, which also form the opening in the shell wall and are introduced into the base of the cover or extend into the base, in order to establish the fluid connection between the interior of the pressure damper housing or the outlet opening on the one hand and the opening in the shell wall on the other. A single bore thus provides both the opening and the recess. By an advantageous arrangement of the bore with respect to the surface of the end face of the base, the bore acts like a recess in the base through which the hydraulic medium flows from the outlet opening to the openings or the opening.The positioning and alignment of at least one bore is possible in a single clamping operation with high accuracy and without additional effort, which allows for reduced tolerances for the outflow path, especially compared to cold forging.

[0013] According to a preferred embodiment of the invention, at least two of these bores are provided, so that the cover element has at least two bores that are at least substantially radially oriented and terminate at intervals from each other in the cover element. With an increasing number of bores, the resistance of the throttling device is reduced, so that the desired resistance of the throttling device can also be advantageously adjusted by selecting the number of bores.

[0014] Furthermore, a preferably uniform distribution of the bores over the circumference of the cover element results in advantageous stability and load-bearing capacity of the throttling device with regard to mechanical loads, which may also result from the spring element that preloads the valve element.

[0015] Furthermore, it is preferably provided that the distance of a bore axis of the respective bore to the end face is smaller than the diameter of the respective bore and is selected in particular depending on a desired throttling effect. Because the bore diameter is always larger than the distance to the end face, it is ensured that the bore is R. 415016

[0016] - 4 -

[0017] The end face is open at the edges, creating a recess in the end face or base of the cover through which the hydraulic fluid can escape. Depending on the specific position of the bore axis and the diameter of the respective bore, the flow cross-section of the outflow path or the inflow cross-section into the bore is advantageously defined to ensure the desired effect of the throttling device. Preferably, the apex angle of the bore and / or the drilling depth of the respective bore are also selected depending on the desired throttling effect.

[0018] Furthermore, it is preferably provided that a flow plate rests on the end face, which has a recess for each bore at its edge, aligned with the bore and overlapping it at least partially. According to this embodiment, the outflow cross-section of the outflow path is not defined solely by the bore, but rather by the flow plate, which closes the bore, particularly partially. This allows the respective bore to be manufactured with tighter tolerances because the smallest flow cross-section of the outflow path is defined by the flow plate and its recess(s). This can further reduce manufacturing costs. Preferably, the flow plate is made of a sheet metal part, with the respective recess being, for example, punched or milled.

[0019] Preferably, the respective recess of the flow plate extends at least substantially radially inwards to ensure an advantageous overlap with the respective bore.

[0020] According to a preferred embodiment of the invention, the outer diameter of the flow plate corresponds at least substantially to the inner diameter of the casing wall. This ensures that the flow cross-section or the inflow cross-section into the outflow path is defined solely by the recess(s) of the flow plate and the underlying bore, and that no or at least in R. 415016

[0021] - 5 -

[0022] Essentially, no hydraulic medium can pass the recess on the flow plate and reach the respective opening in the casing wall.

[0023] A stepped bore is particularly preferred, forming a bypass opening on the outside of the casing wall. The bore section located on the outside of the casing wall has a larger diameter than the bore section extending into the base of the cover or the end face. This provides an advantageous bypass opening on the outside alongside the actual bore, allowing for beneficial leakage from the pressure damper, especially when the line adjoining the opening in the casing wall is closed. Preferably, the stepped bore is designed in three parts, with a third section in addition to the two sections mentioned above. This third section provides a chamfer around the bore entrance on the outside of the casing wall for deburring the cylindrical bore section.

[0024] The pressure damper according to the invention, comprising the features of claim 10, is characterized by the throttling device according to the invention. This results in the advantages already mentioned above. Further advantages and preferred features and combinations of features become apparent in particular from the foregoing and from the claims.

[0025] The invention will now be explained in more detail with reference to the drawing. To this end, we show

[0026] Figure 1 shows an advantageous pressure damper in a simplified form.

[0027] Sectional view

[0028] Figures 2A and B show an advantageous throttling device for the pressure damper in different views.

[0029] Figures 3A to C show a further embodiment of the throttle device in different views. R. 415016

[0030] - 6 -

[0031] Figure 1 shows a simplified sectional view of a pressure damper 1 for a hydraulic braking system of a motor vehicle. The pressure damper 1 has a substantially cup-shaped housing 2 with a cylindrical, in this case circular-cylindrical, outer wall, which has an inlet opening 3 on one end face and an outlet opening 4 on the opposite end face. The outer wall 5 of the housing 2 is closed in this respect. The inlet opening 3 is formed in an otherwise closed base 6 of the housing. A movable valve element 7 is also arranged in the housing 2, which, according to the present embodiment, is designed as a spherical element. The inlet opening 3 has an internal valve seat 8, which is shaped and designed such that the valve body 7 can seal against the valve seat 8 to completely close the inlet opening 3.For example, the inlet opening 3 has a chamfer on the inside for the valve seat 8.

[0032] An advantageous throttling device 9 is further associated with the outlet opening 4. The throttling device 9 has a cover element 10, which is also cup-shaped, with a base 24 and with a shell wall 11 projecting from the base 24. The inner diameter of the shell wall 11 is at least slightly larger than the outer diameter of the shell wall 5 of the housing 2 or corresponds to the outer diameter, so that the throttling device 9 with the shell wall 11 can be slid onto the shell wall 5 of the housing 2 in order to cover or close the outlet opening 4 of the pressure damper 1 with the cover element, in particular with the base 24.

[0033] The evaluation unit 9 has two openings 12 in its casing wall, arranged diametrically opposite each other and each opening into a recess 13 formed on the end face 14 of the base 24 facing the pressure damper 1. The pressure damper 1 rests with its end face, which has the outlet opening 4, on the base 24, specifically on the end face 14 of the base 10, and thus essentially closes the outlet opening 4. Hydraulic fluid that has entered the housing 2 by moving the valve element 7 can leave the housing 2 and escape through the recess 13 and the respective associated opening 12. R. 415016

[0034] - 7 -

[0035] A spring element 15, designed as a coil spring, is held pre-tensioned between the end face 14 and the valve element 7 to press the valve element 7 against the valve seat 8. According to the present embodiment, a displaceable guide sleeve 16 is associated with the spring element 15. This guide sleeve has a collar 17 that covers an end face of the spring element 15 facing the valve element 7 and interacts with the valve element 7 or, optionally, as shown in the embodiment of Figure 1, with support balls 18 located between the valve element 7 and the guide sleeve 16.

[0036] Figures 2A and 2B show the throttle device 9 according to an exemplary embodiment in different views. Figure 2A shows a perspective top view of the front face 14, and Figure 2B shows the throttle device 9 in a detailed sectional view.

[0037] The recesses 13 are designed as bores 19, which extend at least substantially radially into the shell wall 11 or into the base 24, thus creating substantially radial recesses or flow paths. The bores 19 simultaneously form the openings 12 in the shell wall 11, so that both a recess 13 and an opening 12 are produced in a single drilling operation. According to the present embodiment, the bores 19 are aligned with each other but terminate at a distance from one another.

[0038] The respective drilling axis is positioned with respect to the end face 14 such that the distance of the drilling axis to the end face 14 is smaller than the diameter of the respective bore 19. This ensures that the respective bore 19 is radially and openly formed in the ground 24 to provide the recess 13.

[0039] Advantageously, the bores 19 are designed as stepped bores. The throttling device 9 preferably has a mounting chamfer 20 on its outer side, which is particularly useful for centering and ensuring a tight seal (see R. 415016).

[0040] - 8 -

[0041] The throttling device 9 serves as a mounting element on a hydraulic block of a brake system, thereby facilitating the assembly of the pressure damper 1 and the throttling device 9. The mounting chamfer 20 is arranged relative to the base 24 such that the respective opening 12 lies partially within or penetrates the mounting chamfer 20. Preferably, the mounting chamfer 20 extends over the entire circumference of the throttling device 9 or the cover element 10, thereby improving ease of assembly.

[0042] Preferably, the respective bore 19 is designed as a stepped bore with a first section forming the recess 13, which has a first diameter, and with a second section located substantially outside the shell wall 11, which has a second diameter that is larger than the first diameter, in order to form a bypass opening 21 in the area of ​​the mounting chamfer 20 through the larger second diameter, which ensures that hydraulic medium can escape in the mounted state of the pressure damper 1 and the coupling device 9 on a hydraulic block, even when the respective channel of the hydraulic block associated with the opening 12 is blocked or closed.

[0043] The diameter of each bore 19 and the position of the bore axis relative to the end face 14 of each bore 19 define the flow cross-section of the respective recess 13, which in turn determines the hydraulic resistance of the coupling device 9. The precise drilling of each bore 19 ensures the desired throttling resistance of the throttling device 9 with only one clamping and one drilling operation for each bore 19.

[0044] Preferably, the bores 19 are drilled first to prevent the drilling tool from wandering. If the outer and inner contours of the throttle device 9 are then produced either by forming tools or by contour turning, it is ensured that burrs do not protrude in the direction of the subsequent components to be mounted. The selection of the point angle of the respective bore 19, in particular from 45° to 180°, and the axial depth of the respective bore 19 can be used to determine both the R. 415016

[0045] - 9 - The hydraulic connection to the interior of the throttle device 9, as well as the spring bearing surface for the spring element 10 on the end face 14, are optimized. Optionally, by using a step drill with a third drilling section, a chamfer around the bore entrance can also be produced in a single drilling operation to deburr the cylindrical bore section. The possibility of clamping in a single setup also has the advantage that the positioning of the bores 19 relative to the bearing surface of the housing 2 or to the end face 14 can be achieved with high accuracy and without additional effort. Overall, this results in a low tolerance for the outflow cross-section or for the flow cross-section of the outflow path formed by the respective recess 13 and the associated opening 12.

[0046] Figures 3A to C show a further embodiment of the throttle device 9 in different views. Figure 3A shows the throttle device according to the further embodiment in a perspective exploded view, Figure 3B shows the throttle device 9 in a top view, and Figure 3C shows the throttle device 9 in a perspective longitudinal section view.

[0047] In contrast to the previous embodiment, the bores 19 in this case extend only slightly into the base 24 of the throttling device 9. They form the respective opening 12 and a short depression 13 located in the end face 14 of the base 24.

[0048] In addition, the throttling device 9 according to this embodiment has a flow plate 22 which rests on the end face 14 in the assembled state. The flow plate 22 is circular in shape and has two radially open recesses 23. The recesses 23 project radially into the flow plate 22 and are aligned with each other, as are the bores 19, so that in the assembled state the recesses 23 are aligned with the bores 19 and overlap at least partially with the bores 19 or the recesses 13. R. 415016

[0049] - 10 -

[0050] The flow plate 22 transfers the functions of outflow path, spring support surface, and housing support surface for the housing 2 to the separate component of the flow plate 22. This is preferably designed as a sheet metal element. Because sheet metal with very low thickness tolerances is readily available and only small tolerances for the width of the outflow are to be expected from a stamping or etching process, maintaining the desired hydraulic cross-section of the outflow paths of the respective recess 23 can be achieved cost-effectively with high precision and repeatability.

[0051] In addition to a continuous spring support surface that can be designed with a high degree of freedom, the flow plate 22 offers significantly higher strength than the cover element 10 itself when using a suitable sheet metal material and is therefore very well suited for surface pressure against sinking when joining the pressure steamer 1.

[0052] Because the bores 19 are located under the front face of the pressure damper 1 and, in this embodiment, are not responsible for the hydraulic cross-section, the drilling tool can be shorter, thicker, and therefore more stable. Furthermore, in this embodiment, the bypass opening 21 can advantageously be produced directly using a step drill.

[0053] The flow plate 22 is preferably clamped between the pressure damper 1 and the cover element 10, thus preventing the flow plate 22 from rotating during operation. Optionally, the flow plate 22 and the outer wall 11 of the throttling device 9 preferably form an anti-rotation device, which is formed, for example, by at least one tongue-and-groove connection between the flow plate 22 and the outer wall 11. For this purpose, for example, a radially inwardly projecting rib is arranged on the inside of the outer wall 11, extending axially along the outer wall 11, and a radial recess in the flow plate 22 is provided to receive the rib, so that the flow plate 22 can be inserted axially into the throttling device 9, but cannot be rotated relative to it. R. 415016

[0054] - 11 -

[0055] According to a further embodiment, the flow plate 22 also has means for positive locking connection with the spring element 15, which in particular prevent the spring element 15 from twisting and / or ensure the centering of the spring element 15, especially during assembly.

Claims

R. 415016 - 12 - Claims 1. Throttle device (9) for a pressure damper (1) of a hydraulic brake system of a motor vehicle, comprising a cover element (10) that can be attached to a housing (2) of the pressure damper (1) in the area of ​​an outlet opening (4) of the pressure damper (1) and has a base (24) and a shell wall (11) projecting from the base (24) and being at least substantially closed in the circumferential direction, wherein the base (24) has at least one recess (13) extending at least substantially radially on its end face (14) facing the shell wall (11), which opens into an opening (12) in the shell wall (11), characterized in that the recess (13) and the opening (12) are formed by a bore (19) oriented at least substantially radially.

2. Throttle device according to claim 1, characterized in that the cover element (10) has at least two at least substantially radially oriented bores (19) which terminate at intervals from each other in the cover element (10).

3. Throttle device according to claim 2, characterized in that the bores (19) are arranged evenly distributed over the circumference of the cover element (10).

4. Throttle device according to one of the preceding claims, characterized in that a distance of a bore center axis of the respective bore (19) to the end face (14) is smaller than a diameter of the respective bore (19).

5. Throttle device according to one of the preceding claims, characterized in that a flow plate (22), in particular made of sheet metal, rests on the end face (14), which for each bore (19) has a marginal and aligned-with-the-bore (19) and R. 415016 - 13 - each bore (19) has at least partially overlapping recesses (23).

6. Throttle device according to claim 5, characterized in that the respective recess (25) extends at least substantially radially inwards.

7. Throttle device according to one of the preceding claims, characterized in that the respective bore (19) extends less radially inwards than the associated recess (23) of the flow plate (22).

8. Throttle device according to one of claims 5 or 6, characterized in that an outer diameter of the flow plate (22) corresponds at least substantially to the inner diameter of the outer wall (11).

9. Throttle device according to one of the preceding claims, characterized in that the respective bore (19) is a stepped bore to form a bypass opening (21) on the outside of the casing wall (11).

10. Hydraulic pressure damper (1) for a hydraulic brake system of a motor vehicle, comprising a housing (2) having an inlet opening (3) and an outlet opening (4), wherein a valve element (17) for closing the inlet opening (3) is associated with the inlet opening (3), and wherein a throttle device (9) is associated with the outlet opening (4), wherein a spring element (15) is held pre-tensioned between the throttle device (9) and the valve element (17), characterized in that the throttle device (9) is designed according to one of claims 1 to 9.

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