Braking system with simulator unit

Abstract

The invention relates to a braking device (100) for a hydraulic vehicle braking system, comprising at least one simulator unit (1) for generating a reaction force (G) acting against an actuation force (B) and fed back to an actuation element (2) of the braking device (100), the simulator unit having at least one hydraulically operated simulator piston (4) axially movable in a piston bore (3) and at least one sealing element (5) for sealing the simulator piston (4) in the piston bore (3). According to the invention, the sealing element (5) is fastened to the simulator piston (4) and slides on a side surface (6) of the piston bore (3) upon actuation of the simulator piston (4), so that braking devices with different simulator characteristic curves can be produced more economically and efficiently.

Description

[Technical Field]

[0001] The invention relates to a braking device for a hydraulic motor vehicle braking system, in particular for an externally actuatable, electronically controllable brake-by-wire motor vehicle braking system, comprising a simulator unit according to the preamble of claim 1. [Background technology]

[0002] Electronically controlled brake systems, especially so-called brake-by-wire brake systems, are increasingly being used in modern vehicles. Such brake systems offer numerous advantages over conventional brake systems. For example, braking can be performed completely independently of the driver when necessary and can be flexibly adapted to the respective driving situation. Compared to conventional brake systems, the required construction space is reduced, and the brake system can be positioned more flexibly within the vehicle. In normal braking mode, modern brake-by-wire automotive brake systems are indirectly activated in an electronically controlled manner, completely independent of the driver, by sensor-based detection of the driver's braking request. To provide the required system pressure in this normal braking mode, a pressure generator that can be controlled independently of the driver and is usually driven by an electric motor is used.

[0003] In conventional braking systems, when the brake pedal is actuated, pressure from the hydraulic circuit exerts a reaction force that returns the driver to the pedal. This force varies depending on the braking scenario, vehicle load, and road conditions. However, in brake-by-wire systems, such feedback from the wheel brake cylinders to the brake pedal is prevented in normal, externally actuated operating modes by disconnecting the direct hydraulic connection. Therefore, a familiar, comfortable pedal feel must be provided to the driver despite the lack of direct feedback.

[0004] For this purpose, it is known to simulate the feedback using a separate simulator unit, which generates a reaction force acting against the application force and having a defined travel-dependent or stroke-dependent profile, also called the characteristic of the simulator unit, which characteristic should resemble as closely as possible the real feedback found in, for example, a conventional brake system operated by a driver.

[0005] The real feedback is distinguished in particular by the fact that the reaction force initially rises only slightly linearly, but after a certain stroke, the rise becomes increasingly gradual. To achieve such a profile, a complex structure combining various linear and non-linear elastic elements is required, actuated by a simulator piston that is connected by a hydraulic connection directly to the pressure chamber of the master cylinder unit.

[0006] For example, from DE 10 2016 221 403 A1 it is known to arrange the components of the simulator unit in separate bores in the brake equipment housing, which bores are closed by flat covers, such bores usually having complex contours in order to accommodate components of different sizes and sealing elements for sealing the simulator piston.

[0007] The characteristics of the simulator unit or the specific force transfer profile of the simulator unit must be adapted to different vehicle applications. To this end, it is often necessary to change the dimensions of individual components, which affects the bore contours. This necessitates modifying the complex brake equipment housing and manufacturing several variants of this expensive component to achieve different simulator characteristics. Summary of the Invention [Problem to be solved by the invention]

[0008] It is therefore an object of the present invention to make it possible to manufacture brake equipment with different simulator characteristics more efficiently and at lower cost. [Means for solving the problem]

[0009] This object is achieved according to the invention by a braking device having the combination of features set forth in claim 1. The dependent claims specify further advantageous embodiments and developments of the invention.

[0010] The present invention provides a sealing element for sealing the simulator piston, which is fastened to the simulator piston so that when the simulator piston is actuated, the sealing element slides on the side of the piston bore, thus eliminating the need to form radial grooves directly in the side of the piston bore, which can be done more easily and cheaply in the side of the simulator piston.

[0011] In one refinement of the invention, the piston bore can be formed in a separate simulator housing that is fastened to the brake equipment housing and at least partially receives the simulator piston, so that for different versions of the simulator unit only the relatively simple and relatively small simulator housing needs to be changed and no longer the complex brake equipment housing.

[0012] For particularly easy manufacture of the simulator housing, a preferred embodiment of the invention provides the simulator housing to be a cup-like thin-walled shape with a substantially constant wall thickness, for which purpose the simulator housing can be efficiently and inexpensively manufactured from sheet metal, for example by deep drawing.

[0013] To fasten the simulator housing to the brake equipment housing, the brake equipment housing only needs a relatively easily manufactured receiving seat with an interface for sealing fastening of the simulator housing, so that the machining effort and the volume of material removed by cutting from the brake equipment housing are significantly reduced. Furthermore, to facilitate assembly, all components of the simulator unit are housed within the simulator housing and, if necessary, can be shipped pre-installed within the simulator housing, which likewise significantly reduces the assembly effort.

[0014] For an efficient and secure fastening of the simulator unit, the invention proposes that the simulator housing is hydraulically and sealingly fixed to the brake equipment housing by plastic deformation of parts of the brake equipment housing, for example by crimping. In this way, additional seals can be omitted and the assembly cycle time can be reduced.

[0015] In order to prevent a functionally destructive buildup of pressure medium in the simulator housing, the invention proposes that at least one outlet extends through the wall of the simulator housing, through which at least one outlet the invaded pressure medium can escape from the simulator housing.

[0016] In order to ensure the outflow of pressure medium in all operating states of the simulator unit, the invention proposes that the outlet be arranged axially in the region between the working end position of the sealing element and the elastomer element, so that none of the internal components can cover said outlet.

[0017] In order to prevent the escaping pressure medium from leaking into the surroundings, the invention proposes that the outlet opens from the simulator housing into a separate recovery chamber, which is hydraulically sealed and isolated from the surroundings of the brake device.

[0018] In one embodiment of the invention, the recovery chamber may be isolated by a separate cover additionally provided for at least one other component of the braking system, for example a cover for the electronic control unit or the valve assembly.

[0019] In another embodiment of the invention, the recovery chamber may be isolated by a separate isolation element acting directly between the simulator housing and the brake equipment housing.

[0020] In order to be able to arrange the brake device in different spatial orientations and angular positions without further modifications and to simplify the structure of the recovery chamber, the present invention proposes that the recovery chamber annularly surrounds the simulator housing from the radial outside, at least in the area where the discharge outlet opens, or that the recovery chamber surrounds the entire simulator housing.

[0021] In a preferred embodiment of the invention, in order to make the construction of the simulator unit more efficient and inexpensive, the thrust piece provided for introducing the force from the simulator piston into the elastomeric element can be thin-walled with a substantially constant wall thickness, so that said thrust piece can be particularly efficiently and inexpensively stamped out, for example, from sheet metal, ideally in one machining operation.

[0022] Further features and advantages of the present invention will become apparent from the following description. [Brief explanation of the drawings]

[0023] [Figure 1a] 1 shows an external view of an exemplary braking device; [Figure 1b] 1 shows an exemplary braking system with a highly simplified view of its internal structure; [Figure 2] 1 shows an axial cross-sectional detail view of a first embodiment of a braking device with a first variant of an improved simulator unit in an inactivated initial state. [Figure 3] 1 shows a detailed axial section of a second embodiment with a different simulator unit and a differently isolated collection chamber. DETAILED DESCRIPTION OF THE INVENTION

[0024] Figure 1 FIG. 1 shows, by way of example, a typical brake-by-wire braking device 100 for a hydraulic braking system of an automobile.

[0025] To initiate a braking maneuver, the driver uses a brake pedal (not shown here) to actuate an actuating member 2 coupled to said brake pedal. In normal braking mode, this actuation is detected by a sensor device (not shown here) and processed in an electronic control unit 104. The control unit 104 then immediately activates the electric drive unit 102, which generates the required brake pressure using a separate pressure generator (also not shown). A pressure medium reservoir 103 supplies the required pressure medium, for example brake fluid, to the brake system 100.

[0026] An actuation force B from the driver is transmitted to a master cylinder piston 21 which, in a master cylinder unit 20 arranged in the brake equipment housing 101, defines a pressure chamber 22 which is filled with hydraulic medium. In the normal braking mode described above, the pressure chamber 22 is hydraulically connected via a connection 23 to a simulator unit 1 arranged in the brake equipment housing 101 of the brake equipment 100.

[0027] Outside of normal braking operation, at the so-called fallback level, the hydraulic connection 23 is blocked by the shut-off valve 24 and instead the pressure chamber 22 is connected directly to the wheel brakes, also not shown, via further lines not shown here.

[0028] The simulator unit 1 has a piston bore 3 formed in a brake equipment housing 101. A simulator piston 4, a spring element 15 preferably having a linear spring characteristic, a pressure-resistant thrust piece 14, and an elastomer element 7 preferably having a progressive spring characteristic are located in series within the piston bore.

[0029] Upon actuation of the master cylinder unit 10, hydraulic medium is forced from the pressure chamber 11 into the simulator unit 1 and impinges on the simulator piston 4, thus displacing the simulator piston 4 axially in the direction of the elastomeric element 7. A sealing element 5, usually in the form of a sealing sleeve, serves to seal the simulator piston 4 in the piston bore 3 in order to prevent the flow of pressure medium from passing through the simulator piston 4 through a radial gap at the margins.

[0030] In most embodiments, the simulator piston 4 has an axial spacing S relative to the thrust piece 14 in its initial, unactuated position. Upon passing through this axial spacing S, also called the idle stroke, a spring element 15 supported between the simulator piston 4 and the thrust piece 14 is compressed.

[0031] After passing the idle stroke S, the simulator piston 4 abuts against the thrust piece 14 and displaces it, which causes the elastomeric element 7 to be compressed.

[0032] During the actuation operation, the resistance generated within the simulator unit 1, in particular by the spring element 15 and the elastomer element 7, is perceived by the driver as a reaction force G acting against the actuation force B, the magnitude of which varies characteristically along the actuation stroke depending on the structure and design of the individual components of the simulator unit 1.

[0033] Figure 2 FIG. 2 shows a first embodiment of a simulator unit 1 according to the invention in an inactive initial state.

[0034] In contrast to the known embodiment described above, the piston bore 3 is not formed directly in the brake equipment housing 101, but in a separate simulator housing 8 which receives the individual components of the simulator unit 1. In the exemplary embodiment shown, the piston bore corresponds to an inner surface 6 of the simulator housing 8.

[0035] The simulator housing 8 is cup-shaped, has thin walls with a substantially constant thickness over its entire length and is rotationally symmetrical about the central axis M. Such a housing can be produced particularly inexpensively, for example as a deep-drawn part from sheet metal.

[0036] The simulator housing 8 is permanently and hydraulically sealedly connected directly to the braking equipment housing 101. For this purpose, the edge of the simulator housing 8 is flared or flanged radially outwards, and a corresponding circular receiving seat 105 is formed on the braking equipment housing 101. The simulator housing 8 is crimped in the receiving seat 105, with the edge of the simulator housing 8 inserted into the receiving seat 105. During the crimping operation, the material of the braking equipment housing 101 in the edge region of the receiving seat 105 is plastically deformed so that the two parts are permanently forced together, thereby creating a pressure-fit, form-fit and hydraulically sealed connection.

[0037] The hydraulic sealing preferably occurs by direct contact between the simulator housing 8 and the brake device housing 108. However, within the scope of the present invention, the sealing can equally be performed by means of further sealing elements or sealing materials.

[0038] In this embodiment, the thrust piece 14, like the simulator housing 8, is thin-walled and manufactured with a constant wall thickness from sheet metal by deformation, for example by stamping. In cross section, the thrust piece 14 has a centrally located recess 17 which receives the spring element 15 supported between the thrust piece 14 and the simulator piston 4 and prevents said spring element from tilting under load.

[0039] The sealing element 5 of the simulator unit 1 according to the invention is fastened to the simulator piston 4 in a radial groove so that during operation said sealing element slides on the inner surface 6 of the piston bore 3 or simulator housing 8 .

[0040] In practice, for example, wear or excessive pressure can cause small amounts of pressure medium to flow past the sealing element 5 and collect in the simulator housing 8 in the area between the housing base and the simulator piston 4, with the effect of expelling air from this area. If a relatively large amount of incompressible pressure medium collects in this area, the simulator piston 4 can no longer move during operation, which would mean a complete failure of the simulator unit 1.

[0041] To prevent such malfunctions, one or more outlets 10 are provided in the simulator housing 8, through which the pressure medium that has passed through the sealing element 5 into the simulator housing 8 can flow out again. The outlets 10 are openings that penetrate the wall of the simulator housing 8 and can take the form of, for example, bores or slots. In order to ensure that the outflow of pressure medium remains as unhindered as possible, the outlets 10 are arranged axially in the region between the elastomeric element 7 and the sealing element 5 when the sealing element 5 is in its maximum activated position, i.e. at the maximum possible distance from its initial, non-activated position.

[0042] On the outside of the simulator housing 8, an outlet 10 opens into a separate recovery chamber 11 which, in the embodiment shown, surrounds from the outside substantially the entire simulator housing 8. Via an outlet channel 16, the pressure medium passes from the recovery chamber 11 into a drainage system (not shown here) of the braking device 100, which drains the recovered brake fluid back into the brake circuit.

[0043] The recovery chamber 11 is hydraulically sealed and isolated from the environment in order to prevent uncontrolled leakage of pressure medium into the environment of the braking device 100. In the embodiment shown, the recovery chamber 11 is isolated by a cover 12 of another component of the braking device 100, for example a cover of the control unit 104, which cover 12 is correspondingly enlarged and shaped for this purpose.

[0044] Figure 3 FIG. 3 shows another embodiment of the braking device 100 and of the simulator unit 1 .

[0045] In contrast to the embodiment according to FIG. 2, the collection chamber 11 surrounds the simulator housing 8 substantially annularly at the radial periphery of the latter, in particular in the region where the outlet 10 opens.

[0046] To isolate the recovery chamber 11 from the environment, a separate annular isolation element 13 is provided which acts as a direct seal between the simulator housing 8 and the brake device housing 101 .

[0047] In the illustrated embodiment, the axial distance S between the simulator piston 4 and the thrust piece 14, i.e., the idle stroke, is further reduced to zero so that the simulator piston 4 rests on the thrust piece 14 even in the initial, unactivated state. This characteristic of the simulator unit 1 is very progressive from the start, resulting in a firm, direct brake pedal feel, similar to that found in very sporty cars. In this embodiment, the spring element 15 essentially functions as a return spring. After the braking operation ends, the spring element 15 retracts the simulator piston 4 to its initial, unactivated position more quickly and reliably than if it were to retract solely as a result of the relatively inert reaction of the elastomeric element 7. Furthermore, the spring element 15 ensures that the thrust piece 14 is always pressed against and always remains in contact with the elastomeric element 7, regardless of the piston position. The present invention may also include the following aspects: 1. A brake device (100) for a hydraulic vehicle braking system, comprising at least one simulator unit (1) for generating a reaction force (G) acting against an actuation force (B), said reaction force (G) being fed back to an actuating member (2) of the brake device (100), said at least one simulator unit (1) having at least one hydraulically operated simulator piston (4) axially displaceable within a piston bore (3) and having at least one sealing element (5) for sealing said simulator piston (4) within said piston bore (3), characterized in that said sealing element (5) is fastened to said simulator piston (4) and slides on a side surface (6) of said piston bore (3) when said simulator piston (4) is actuated. 2. A brake device (100) as described in 1 above, characterized in that the simulator piston (4) acts mechanically indirectly or directly on the elastomer element (7) along at least a part of its displacement stroke, causing elastic deformation of the elastomer element (7). 3. A brake device (100) as described in 1. or 2. above, characterized in that the piston bore (3) is formed in a separate simulator housing (8) that is fastened to the brake device housing (101) and that at least partially receives the simulator piston (4). 4. The brake device (100) according to claim 3, wherein the simulator housing (8) is a cup-shaped thin-walled part having a substantially constant wall thickness, and is formed as a deep-drawn part, in particular from sheet metal material. 5. The brake device (100) according to 3. or 4. above, wherein the simulator housing (8) is fastened by plastic deformation of a part of the brake device housing (101). 6. The brake device (100) according to any one of the above items 3 to 5, characterized in that at least one exhaust port (10) extends through the wall (9) of the simulator housing (8). 7. A brake device (100) as described in 2. or 6. above, characterized in that the discharge port (10) is arranged axially in the region between the operating end position of the sealing element (5) and the elastomer element (7). 8. A braking device (100) as described in 6. or 7. above, characterized in that the discharge port (10) opens outward from the simulator housing (8) into a separate collection chamber (11) that is hydraulically sealed and isolated from the surroundings of the braking device (100). 9. A braking device (100) according to claim 8, characterized in that the recovery chamber (11) is isolated by a separate cover (12) for other further components of the braking device (100). 10. A brake device (100) as described in item 8., characterized in that the recovery chamber (11) is isolated by an isolation element (13) acting between the simulator housing (8) and the brake device housing (101). 11. A brake device (100) described in any one of 8. to 10. above, characterized in that the recovery chamber (11) surrounds the simulator housing (8) from the radially outside at least in the area where the discharge outlet (10) opens. 12. A brake device (100) described in any one of 2. to 10. above, characterized in that at least one thrust piece (14) configured to introduce force from the simulator piston (4) to the elastomer element (7) is arranged axially between the simulator piston (4) and the elastomer element (7), and at least a portion of the thrust piece (14) is always in contact with the elastomer element (7). 13. A brake device (100) as described in item 12 above, characterized in that at least one spring element (15) is arranged between the simulator piston (4) and the thrust piece (14). 14. The brake device (100) according to item 12 or 13 above, wherein the thrust piece (14) has a thin-wall shape with a substantially constant wall thickness. 15. A brake device (100) according to claim 14, characterized in that the thrust piece (14) is formed from sheet metal, in particular as a stamped part. [Explanation of symbols]

[0048] 1 Simulator unit 2. Operating member 3 Piston bore 4 Simulator Piston 5 Sealing Elements 6 Side 7 Elastomer Elements 8 Simulator cabinet 9. Wall 10 Outlet 11 Recovery Room 12 Cover 13 Isolation elements 14 Thrust piece 15 Spring elements 16 Outlet channel 17. Depression 20 Main cylinder unit 21 Main cylinder piston 22 Pressure Chamber 23 Connection 24 Shut-off valve 100 Brake equipment 101 Brake device housing 102 Drive unit 103 Pressure medium vessels 104 Electronic Control Unit 105 Receptacle B Actuation force G reaction force M center axis S Axial Spacing

Claims

1. A brake device (100) for a hydraulic vehicle brake system, comprising at least one simulator unit (1) for generating a reaction force (G) acting against an actuation force (B), said reaction force (G) being fed back to an actuating member (2) of the brake device (100), said at least one simulator unit (1) having at least one hydraulically operated simulator piston (4) axially displaceable in a piston bore (3) and having at least one sealing element (5) for sealing said simulator piston (4) in said piston bore (3). 100), characterized in that the sealing element (5) is fastened to the simulator piston (4) and slides on a side surface (6) of the piston bore (3) when the simulator piston (4) is actuated, the piston bore (3) is formed in a separate simulator housing (8) fastened to a brake device housing (101) and at least partially receiving the simulator piston (4), and at least one exhaust port (10) extends through a wall (9) of the simulator housing (8).

2. 2. The braking device (100) according to claim 1, characterized in that the simulator piston (4) acts mechanically, indirectly or directly, on an elastomer element (7) along at least a part of its displacement stroke, causing an elastic deformation of the elastomer element (7).

3. 3. The braking device (100) according to claim 1 or 2, characterized in that the simulator housing (8) is formed in a cup-like thin-walled shape with a substantially constant wall thickness or as a deep-drawn part from sheet metal material.

4. The brake device (100) according to any one of claims 1 to 3, characterized in that the simulator housing (8) is fastened by plastic deformation of a part of the brake device housing (101).

5. 3. The braking device (100) according to claim 2, characterized in that the outlet (10) is arranged axially in the region between the working end position of the sealing element (5) and the elastomer element (7).

6. The brake device (100) according to any one of claims 1 to 5, characterized in that the outlet (10) opens outward from the simulator housing (8) into a separate collection chamber (11) that is hydraulically sealed and isolated from the surroundings of the brake device (100).

7. 7. Brake device (100) according to claim 6, characterized in that the recovery chamber (11) is isolated by a separate cover (12) for other further components of the brake device (100).

8. 7. The braking device (100) according to claim 6, characterized in that the recovery chamber (11) is isolated by an isolation element (13) acting between the simulator housing (8) and the braking device housing (101).

9. The brake device (100) according to any one of claims 6 to 8, characterized in that the recovery chamber (11) surrounds the simulator housing (8) from the radially outside at least in the area where the discharge port (10) opens.

10. 3. The braking device (100) according to claim 2, characterized in that at least one thrust piece (14) configured to introduce a force from the simulator piston (4) to the elastomeric element (7) is arranged axially between the simulator piston (4) and the elastomeric element (7), and that the thrust piece (14) is always at least partially in abutment against the elastomeric element (7).

11. 11. Brake device (100) according to claim 10, characterized in that at least one spring element (15) is arranged between the simulator piston (4) and the thrust piece (14).

12. 12. Brake device (100) according to claim 10 or 11, characterized in that the thrust piece (14) is thin-walled with a substantially constant wall thickness.

13. 13. Brake device (100) according to claim 12, characterized in that the thrust piece (14) is formed as a stamped part or from sheet metal material.

Images