Pressure accumulator for hydraulic assembly
The pressure accumulator in vehicle brake systems uses an elastomeric ring with a lamellar ring to minimize friction and wear, enhancing sealing and reducing production costs by allowing for less precise manufacturing tolerances, thus improving the medium separation in brake systems.
Patent Information
- Application Number
- CN202110649165.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Priority Date
- 2020-06-15
- Filing Date
- 2021-06-10
- Publication Date
- 2024-12-17
- Estimated Expiration
- 2041-06-10
AI Technical Summary
Existing vehicle brake systems face challenges in achieving efficient medium separation between fluid and storage spaces in pressure accumulators, leading to high friction and wear, which complicates the design and increases costs.
A pressure accumulator design featuring a piston with an elastomeric ring and a lamellar ring, where the lamellar ring is fixed to the piston and pressed against the piston guide, providing a lubricating film effect while minimizing friction and wear, and is made of a material with higher elasticity than the elastomeric ring.
The solution reduces friction and wear, allowing for lower production costs and improved performance by enabling the use of coarser dimensional tolerances in manufacturing, while maintaining effective sealing and lubrication.
Smart Images
Figure CN113799752B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a pressure accumulator of a hydraulic assembly of a vehicle brake system, the pressure accumulator having a piston and a seal which seals the piston relative to a piston guide, wherein the seal is provided with an elastomeric ring which is fastened to the piston. Background Art
[0002] For vehicle brake systems of vehicles such as cars and trucks, it is generally known that hydraulic fluid is distributed to the associated vehicle brakes by means of a hydraulic assembly. For such regulation of the brake pressure on the vehicle brake, it is also generally known that one or more pressure reservoirs are provided in the vehicle brake system and in particular in the hydraulic assembly itself. The pressure reservoir is used in particular to improve the response of the associated brake. A pressure reservoir with a piston that can be moved in a piston guide is used. The piston separates the fluid space side, in which the brake fluid is located, from the storage space side. Prestressable elements, such as air cushions and / or mechanical springs, are located on the storage space side. This pressure reservoir is also referred to in particular as a low-pressure pressure reservoir. Summary of the invention
[0003] The object of the present invention is to further develop such a pressure accumulator of a hydraulic assembly of a vehicle brake system and in particular to improve its properties at the medium separation boundary between the fluid space and the storage space.
[0004] According to the present invention, a pressure accumulator of a hydraulic assembly of a vehicle brake system is proposed, the pressure accumulator having a piston and a seal that seals the piston relative to a piston guide, wherein the seal is provided with an elastomeric ring fixed to the piston. A layered ring is also provided, which is fixed to the piston and pressed against the piston guide by the elastomeric ring. The so-called layered ring is understood here to be a ring that forms a "layer" between the piston guide and the elastomeric ring, in other words, the ring thickness of the layered ring in the radial region between the piston guide and the elastomeric ring is smaller relative to its ring width in the axial direction. It refers to a ring that is relatively thin in the radial direction and relatively wide in the axial direction, that is, in particular in this region, it is thinner in the radial direction relative to its length in the axial direction.
[0005] By means of the technical solution according to the present invention, the pre-tensioning of the elastomeric ring is transferred to the lamellar ring, so that the contact pressure transmitted by the elastomeric ring is mapped in the sealing gap between the lamellar ring and the piston guide. Compared with conventional O-ring seals, less friction can be achieved between the seal and the piston guide. As a result, an effect similar to that of a low-friction sealing lip can be achieved with respect to the formation of a lubricating film on the piston guide, without the disadvantages of the sealing lip. For conventional sealing lips, higher dimensional requirements must be made with respect to the fixing of the seal on the piston than are required by the technical solution according to the present invention. The lamellar ring according to the present invention is preferably made of a material with less elasticity than the elastomeric ring, wherein its coefficient of elasticity (elastic modulus) is in particular greater than the coefficient of elasticity of the elastomeric ring. The lamellar ring preferably has a strength greater than 500 N / mm 2 , especially greater than 700N / mm 2 In contrast, the elastomeric ring preferably has an elastic modulus of less than 100 N / mm 2 , especially less than 70N / mm 2 The elastic modulus.
[0006] In an advantageous improvement of the technical solution according to the invention, the lamellar ring has an L-shaped cross section and has retaining legs bent toward the piston. The retaining legs are used to fix the lamellar ring according to the invention on the piston in a positionally determined manner as much as possible. Therefore, in particular, an accurate relative position between the elastomeric ring and the lamellar ring can be ensured throughout the service life of the pressure storage device according to the invention. A lamellar ring of this type preferably also has a sealing leg that rests on the piston guide and with which the above-mentioned layer is formed between the elastomeric ring and the piston guide. According to the invention, an advantageous retaining leg is preferably fixed on the piston in a piston groove. The elastomeric ring is also preferably located in this piston groove, wherein the retaining leg is particularly preferably pressed against the side wall of the piston groove by the elastomeric ring in the axial direction.
[0007] Alternatively, the lamellar ring preferably has a T-shaped cross section and is provided with retaining legs bent toward the piston. Thus, the retaining legs are designed to be wider in the axial direction compared to an L-shaped lamellar ring. This brings further advantages in terms of friction and sliding properties between the piston and the piston guide.
[0008] The retaining legs are preferably arranged on the side of the elastomeric ring that is bent toward the storage space of the piston. The layered ring is thus fixed to the storage space side of the elastomeric ring, so that when the piston is moved into the storage space, the layered ring is pulled, and when the piston is moved out, the layered ring is pushed. This supports the particularly advantageous effect of the layered ring in forming a lubricating film that is similar to a sealing lip. During the movement in, the lubricating film is pulled by the hydraulic fluid, and during the movement out, the lubricating film is pushed away again.
[0009] The lamellar ring according to the invention is further preferably made of plastic, wherein the term plastic in the present case is understood to mean only thermoplastics and thermosetting plastics. This serves in particular to distinguish it from metal or other non-plastic materials.
[0010] Furthermore, the cross section of the elastomeric ring according to the invention is preferably designed to be asymmetrical. In particular, it can be achieved that the lubricating film between the piston and the piston guide does not have the same strength or thickness for both radial directions of movement of the piston. More precisely, an asymmetrical contact pressure curve for controlling leakage is also achieved with the asymmetrical seal during the reciprocating movement of the piston.
[0011] The elastomer ring advantageously has a steep sealing flank from its contact area on the lamellar ring to the fluid space side of the piston. A steep sealing flank is understood to mean that, viewed in cross section, the lateral angle between the surface of the sealing flank and the piston guide is between 12° and 45°, in particular between 15° and 30°. The steep sealing flank serves to push the hydraulic fluid out of the piston guide when the piston is moved out of the storage space.
[0012] Additionally or alternatively, the asymmetrical elastomeric ring has a flat sealing flank from its contact area on the lamellar ring to the storage space side of the piston. A flat sealing flank is understood to mean that, viewed in cross section, the lateral angle between the surface of the sealing flank and the piston guide is between 0° and 10°, in particular between 2° and 8°. The flat sealing flank serves to deposit a certain amount of hydraulic fluid on the piston guide in a targeted manner when the piston is moved into the storage space.
[0013] Preferably, the elastomeric ring of the pressure reservoir according to the invention is fixed on the piston in a piston groove. The piston groove can be produced with relatively rough dimensional tolerances, thereby saving production costs.
[0014] Furthermore, in the pressure reservoir according to the invention, the piston is made of plastic, in particular of fiber-reinforced plastic. This allows the production costs to be further reduced. At the same time, the solution according to the invention also ensures that as little wear as possible occurs on a piston of this type, and in particular that no glass fibers are exposed due to wear of the piston surface. As little wear as possible occurs, otherwise additional guide rings or the like would be required, which would result in a greater overall length of the piston. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The following is a more detailed explanation of an embodiment of the technical solution according to the present invention with reference to the attached schematic drawings. The drawings show:
[0016] Figure 1 shows a hydraulic circuit diagram of a vehicle brake system in which a pressure accumulator is arranged;
[0017] Figure 2 shows a longitudinal section through a first pressure storage device according to the prior art;
[0018] Figure 3 shows a longitudinal section through a second pressure storage device according to the prior art;
[0019] Figure 4 shows a longitudinal section through a first exemplary embodiment of a pressure store according to the invention; and
[0020] Figure 5 A second exemplary embodiment of a pressure store according to the invention is shown in longitudinal section. DETAILED DESCRIPTION
[0021] Figure 1 An embodiment of a vehicle brake system 10 is shown, which is commonly used and installed in a conventional manner in modern motor vehicles. The vehicle brake system 10 comprises four wheel brakes 12, Figure 1 The two wheel brakes 12 shown on the left in FIG. 1 are assigned to the front wheels of the corresponding motor vehicle and are Figure 1 The two wheel brakes 12 shown on the right in the figure are assigned to the rear wheels of the corresponding motor vehicle. Alternative distribution methods are also possible. The vehicle brake system 10 also includes a plurality of hydraulic lines 14, to which components with different functions are connected. These components include a brake actuator 16 with a master brake cylinder, a brake force booster and a brake pedal, as well as a main switching valve 18, a switching valve 20, a damper 22, a return pump 24, a motor 26, an inlet valve 28, an outlet valve 30, a check valve 32 and a pressure storage device 34. These pressure storage devices 34 are connected to the hydraulic lines 14 that are fluid-conducting between the outlet valve 30 and the check valve 32. These pressure storage devices are suitable for, in which the hydraulic fluid or brake fluid supplied from the brake actuator 16 to the wheel brake 12 can be quickly discharged from the wheel brake 12 again by means of the outlet valve 30.
[0022] Figure 2 and 3Two embodiments of conventional pressure storage devices 34 are shown. Both embodiments each have a housing 36 made of aluminum with a cylindrical fluid space 38 formed therein. The fluid space 38 is delimited by an end wall 40 and a cylindrical piston guide 42. A piston 44 is supported movably in the piston guide 42. The piston 44 thus delimits a storage space 46 relative to the fluid space 38. A helical spring 48 made of metal is arranged in the storage space 46, which is supported at the end on a cover 50 likewise made of metal and thus presses the piston 44 toward the fluid space 38. As described above, the fluid space 38 is coupled to the rest of the hydraulic line 14 in a fluid-conducting manner by means of a line 52. The fluid space 38 is thus filled with brake fluid that is also located in the hydraulic line 14.
[0023] The piston 44 is also correspondingly sealed relative to the piston guide 42 by means of a seal, wherein in accordance with Figure 2 In the embodiment shown, a seal 54 is provided in the form of an elastomeric ring with an O-shaped cross section. Figure 3 In the embodiment shown, the seal 56 is designed as an elastomeric ring with a V-shaped cross section, which forms a sealing lip with one of its sealing legs on the piston guide 42. The so-called elastomeric ring is supported on the associated piston 44 in each case in a piston groove 58 extending around its cylindrical circumference and having a rectangular cross section. Figure 3 In the embodiment shown, two guide rings 60 made of a harder plastic than the elastomeric rings are required at the axial end regions of the piston 44, whereby the axial length of the piston 44 is greater than in the embodiment shown. Figure 2 The axial length is longer in the embodiment shown.
[0024] exist Figure 4 and 5 1 and 2 show an embodiment of a pressure storage device 34 according to the invention, wherein Figure 2 and 3 The embodiment shown has correspondingly a housing 36 , a fluid space 38 , an end wall 40 , a piston guide 42 , a piston 44 , a reservoir space 46 , a spring 48 , a cover 50 and a line 52 .
[0025] However, in these exemplary embodiments, the design of the seal between the piston 44 and the piston guide 42 is different from that in the previous embodiment. For this seal, in both embodiments, a layered ring 66 made of plastic is provided on the radial outside of the elastomer ring 64, the layered ring 64 being fixed on the piston 44 and pressed against the piston guide 42 by the elastomer ring 64.
[0026] In accordance with Figure 4In the illustrated embodiment, the lamellar ring 66 has an L-shaped cross section and is provided with a retaining leg 68 bent toward the piston 44 and a sealing leg 70 extending parallel to the piston guide 42. The sealing leg 70 is bent away from the retaining leg 68 toward the fluid space 38. Figure 5 The illustrated embodiment shows a lamellar ring 66 which has a T-shaped cross section and which, in addition to the sealing leg 70 and the retaining leg 68 which is parallel to the piston guide 42, also has a sliding leg 72 which is bent toward the storage space 46. The sliding leg 72 is therefore also located between the outer circumferential surface of the piston 44 and the piston guide 42, so that there, like the sealing leg 70, wear of the material of the piston 44 is avoided when the piston 44 moves back and forth inside the piston guide 42.
[0027] The elastomeric ring 64, which presses the lamellar ring 66 against the piston guide 42, thus establishes a sealed connection between the piston 44 and the piston guide 42 by means of the lamellar ring 66, and at the same time ensures that the piston guide 42 is free from wear by means of the lamellar ring 66. The cross section of the elastomeric ring 64 is designed to be asymmetrical, that is, it has sealing sides with different slopes that are bent toward the lamellar ring 66, so that these sealing sides are not axisymmetric with respect to the radial direction when viewed in the cross section. Here, the elastomeric ring 64 is provided with a steep sealing side 74 from its contact area on the lamellar ring 66 to the side of the fluid space or to the side of the fluid space 38, and with a flat sealing side 76 from its contact area on the lamellar ring 66 to the side of the storage space or to the side of the storage space 46. The flat sealing side 76 has a lateral angle 78 of 10° between the surface of the sealing side 76 and the piston guide 42 when viewed in the cross section. In this case, the steep sealing flank 74 measures at a lateral angle 80 of 25°.
[0028] The elastomer ring 64 is also held in a positionally defined manner on the piston 44 by means of the piston groove 58, just like the seals 54 and 56. Due to the sealing and at the same time anti-friction effect of the lamellar ring 66, the piston groove 58 can be manufactured with relatively coarse dimensional tolerances. Figure 4 and 5 The piston 44 shown may also be made of fiber-reinforced plastic.
[0029] List of reference numerals:
[0030] 10 Vehicle braking equipment
[0031] 12 Wheel brakes
[0032] 14 Hydraulic lines
[0033] 16 Brake actuator
[0034] 18 Main switching valve
[0035] 20 Switching valve
[0036] 22 Damper
[0037] 24 Oil return pump
[0038] 26 Motor
[0039] 28 Inlet valve
[0040] 30 Outlet valve
[0041] 32 Check valve
[0042] 34 Pressure storage
[0043] 36 Housing
[0044] 38 Fluid Space
[0045] 40 end wall
[0046] 42 Piston guide
[0047] 44 Piston
[0048] 46 Storage Space
[0049] 48 Spring
[0050] 50 Lid
[0051] 52 Pipeline
[0052] 54 Seal (O-shaped elastomeric ring)
[0053] 56 Seal (V-shaped elastomer ring)
[0054] 58 Piston groove
[0055] 60 Guide ring
[0056] 62 Seal according to the present invention
[0057] 64 Elastomer Ring
[0058] 66 Lamellar Ring
[0059] 68 Keep your legs
[0060] 70 Sealing Legs
[0061] 72 Sliding Legs
[0062] 74 Steep sealing sides
[0063] 76 Smooth sealing profile
[0064] 78 Side Angle
[0065] 80 lateral angle
Claims
1. A pressure accumulator (34) of a hydraulic assembly of a vehicle brake system (10), the pressure accumulator having a piston (44) and a seal for sealing the piston (44) relative to a piston guide (42), wherein the seal is provided with an elastomeric ring (64) fixed to the piston (44), wherein a lamellar ring (66) is provided, the lamellar ring being fixed to the piston (44) and being pressed against the piston guide (42) by the elastomeric ring (64), and the elastomeric ring (64) being protected from wear on the piston guide (42) by means of the lamellar ring (66), wherein the elastomeric ring (64) has a steep sealing side (74) from its contact area on the lamellar ring (66) to the fluid space side of the piston (44), and the elastomeric ring (64) has a flat sealing side (76) from its contact area on the lamellar ring (66) to the storage space side of the piston (44).
2. The pressure storage device according to claim 1, characterized in that The lamellar ring (66) has an L-shaped cross section and is provided with retaining legs (68) bent toward the piston (44).
3. The pressure storage device according to claim 1, characterized in that The lamellar ring (66) has a T-shaped cross section and is provided with a retaining leg (68) bent toward the piston (44).
4. The pressure storage device according to claim 2, characterized in that The retaining legs (68) are arranged on a side of the elastomeric ring (64) that is bent toward the storage space of the piston (44).
5. The pressure storage device according to claim 3, characterized in that The retaining legs (68) are arranged on a side of the elastomeric ring (64) that is bent toward the storage space of the piston (44).
6. The pressure storage device according to claim 1, characterized in that The lamellar ring (66) is made of plastic.
7. The pressure storage device according to claim 1, characterized in that The cross-section of the elastomeric ring (64) is asymmetrical.
8. The pressure storage device according to claim 1, characterized in that The elastomeric ring (64) is fixed on the piston (44) in a piston groove (58).
9. The pressure storage device according to claim 1, characterized in that The piston (44) is made of plastic.
10. The pressure storage device according to claim 9, characterized in that The piston (44) is made of fiber-reinforced plastic.