A hydraulic unit, in particular for supplying a pressure medium at brake pressure to a brake circuit of a vehicle brake system

Abstract

To provide a liquid pressure unit which is constituted to be compact and inexpensive, and which comprises a buffer mechanism for buffering pressure pulsation of a pressure generator that can be easily mounted.SOLUTION: Well-known liquid pressure units each comprise a pressure generator. However, the pressure generator causes pressure pulsation. In order to buffer the pressure pulsation, a buffer mechanism is used. According to a proposal of the present invention, a throttle element (70) abuts on a first support body (74a) using an upper surface and abuts on a second support body (74b) using a lower surface, in a state that pressure is not acting thereon. The support bodies (74a and 74b) are formed on mutually opposing sides of a gap (72). Advantageously, the throttle element (70) does not have to be provided with an elastic element for pre-tensioning itself in an axial direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The invention relates to a hydraulic unit, in particular for supplying a brake circuit of a vehicle brake system with pressure medium at brake pressure, with the features of the preamble of claim 1 .

[0002] Electronically slip-controllable vehicle brake systems are well known from the state of the art. The main components of such vehicle brake systems form a so-called hydraulic unit, in which, inter alia, a pressure generator, a motor for driving the pressure generator, an electromagnetically operable valve and an electronic control for electrically activating these components are arranged in a housing block. The hydraulic unit supplies the wheel brakes, which are connected to one another in a brake circuit, with pressure medium at brake pressure, which can be adapted for each wheel by means of a number of valves to the slip situation prevailing at the respective wheel. The aim here is to avoid wheel slip caused by targeted braking interventions and the unstable driving situations which result from this. Slip-controllable vehicle brake systems are variously known as vehicle brake systems with antilock brake control (ABS control), antispin control (ASR control) or drive stability control (ESP). [Background technology]

[0003] To deliver the pressure medium, pressure generators are often used, in which the pressure medium is delivered by a piston. Due to the periodic delivery of pressure medium by such pressure generators, pressure pulsations can occur in the connected brake circuit, which are uncomfortable for the passengers and reduce driving comfort.

[0004] To damp the pressure pulsations, it is known to use a damping mechanism on the pressure side of the pressure generator. The damping mechanism comprises a hydraulic cavity whose volume is variable as a function of pressure and a throttle mechanism arranged downstream of this cavity. Throttling mechanisms with a constant throttle cross-sectional area or with a variable pressure-dependent cross-sectional area are also in the state of the art. The latter throttle mechanisms are characterized by adapting their throttling characteristics to the pressure medium-conveying volume or to the prevailing pressure ratio.

[0005] A pressure generator in which a damping mechanism, the throttle cross-sectional area of ​​which is variable depending on the pressure, is arranged downstream in terms of flow technology is disclosed, for example, in US Pat. No. 5,399,323.

[0006] Furthermore, in the pressure generator known from DE 10 200 03 133 A1, a throttle element is arranged on the outer periphery of the pressure generator. This throttle element is located in a gap formed between the pressure generator and a pump receptacle in the housing block of the hydraulic unit. The rigid throttle element, which is embodied as a ring, is pressed against a valve seat by an elastic element. The elastic element is supported on a step on the periphery of the pressure generator. The valve seat is formed on the pump element-side end face of a plug, which seals the pump receptacle against the surroundings.

[0007] Disadvantages of this arrangement are the large number of separate components that are assembled in different work steps, the relatively large installation space required for this throttle mechanism, and the costly precision manufacturing of the individual components of the throttle mechanism so that the resulting throttle characteristic is within the desired tolerance range. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] German Patent Application Publication No. 102011075518A1 [Patent Document 2] German Patent Application Publication No. 102010040157A1 Summary of the Invention

[0009] In contrast, the subject matter according to claim 1 has the advantage that no elastic element for pretensioning the throttle element needs to be provided in the throttle mechanism without substitution. This saves component and assembly costs as well as the installation space required for producing the throttle mechanism. The throttle element according to the invention cooperates with two supports which can be produced cost-free when the pump receptacle is produced in the housing block or when the liner is produced. The pretension of the throttle element can be adjusted by changing the axial distance between the supports, thus allowing a simple adaptation of the throttle and damping properties to the respective application. Furthermore, the variation of the throttle properties can be achieved by the cross-sectional shape, material selection and / or construction of the throttle element and the geometric shape of the supports. In general, arranging the throttle element on the circumference of the piston pump and thus away from the hydraulic cavity of the damping mechanism allows freedom in the shaping of the hydraulic cavity and in the installation process.

[0010] Further advantages and advantageous further configurations of the invention are evident from the dependent claims or the following description.

[0011] An embodiment of the invention is illustrated in the drawings and explained in detail in the following description. [Brief description of the drawings]

[0012] [Figure 1] 1 is a longitudinal cross-sectional view of a portion of a hydraulic unit of a vehicle brake system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The part of the hydraulic unit 10 shown in the figures shows a housing block 12 with a pump receptacle 14 formed therein and opening on the outer surface of the housing block 12. The pump receptacle 14 is cylindrical, extends in the direction of a longitudinal axis XX and is stepped in its internal dimensions from the outside to the inside. A pressure generator 16 is inserted into the pump receptacle 14, which is only partially visible in the figures. The pressure generator 16 is a piston pump, the piston 18 of which is slidably received in a cylindrical liner 20 closed on one side and can be driven for reciprocating motion. As pump drive, for example, a rotationally driven eccentric or cam is used, which acts with its outer periphery on the piston bottom. The piston bottom and the pump drive are not visible in the figures.

[0014] Only the open end of the piston skirt, facing the piston bottom, of the piston 18 is shown. At the open end, a valve seat 22 of an intake valve 24 is formed. The valve seat 22 surrounds an intake valve cross section 26 controlled by an intake valve ball 28. To this end, the intake valve ball 28 is pressed against the valve seat 22 by an intake valve spring 30. The intake valve spring 30 is tensioned under axial pretension between the intake valve ball 28 and a pin 34 which projects centrally into the working space 32 of the piston pump.

[0015] A high-pressure sealing element 36 is fixed on the outer periphery of the piston 18 in the region of the valve seat 22. The high-pressure sealing element is embodied in the form of a ring and seals a guide gap 38 between the piston 18 and the inner wall of the liner 20 by means of a circumferentially extending sealing lip. A piston return spring 40 engages with one of its ends on the end face facing the working chamber 32 of the high-pressure sealing element 36. The opposite end of the piston return spring 40 rests against the closed end of the liner 20 and presses the piston 18 indirectly, via the acting high-pressure sealing element 36, in the direction of the pump drive, not visible in the figure.

[0016] At the closed end of the liner 20 there is a piston pump discharge valve 42, which is also formed as a check valve. It comprises a conically shaped discharge valve seat 44, a discharge cross section 46 surrounded by the discharge valve seat 44 and a discharge valve ball 48 which is spring acted upon to control the discharge valve cross section 46. A discharge valve spring 50 is supported at its base in a blind hole-shaped valve spring receptacle 52 in the centre of the plug 54 and presses the discharge valve ball 48 against the discharge valve seat 44 with its opposite end.

[0017] The plug 54 closes the pump receptacle 14 of the housing block 12 relative to the environment. For this purpose, the plug 54 is pressed into the pump receptacle 14 and can additionally be positively connected to the hydraulic unit by crimping the material of the housing block 12.

[0018] In the region of the closed end of the liner 20, a packing ring 58 is arranged in a circumferentially extending, outwardly opening annular groove 56. This packing ring 58 seals off the different annular chambers 60a, 60b formed around the circumference of the pressure generator 16 in the pump receptacle 14 from one another. The first annular chamber 60a is located on the side of the pump receptacle 14 at the opening closed by the plug 54. It communicates with the discharge valve 42 for conducting the pressure medium and serves to discharge the pressure medium expelled by the piston 18 from the working space 32 by the piston pump. For this purpose, a pressure medium passage 62 emerges from the first annular chamber 60a, which is illustrated as running obliquely in the figure.

[0019] The conveyed pressure medium reaches the damping mechanism through this pressure medium passage 62. Only the damping mechanism's damper installation space 64 in the housing block 12 is shown in the figure. This damping mechanism's damper installation space 64 is arranged immediately to the left of the first pressure medium passage 62. An outlet 66 emerging from the damping part installation space 64 leads into a second annular chamber 60b which, as already mentioned, is sealed off from the first annular chamber 60a by the packing ring 58 of the liner 20.

[0020] Downstream of the discharge 66 of the damping device in the flow direction of the pressure medium, a pressure medium conveying channel 68 emerges from the second annular chamber 60b, via which the pressure generator 16 is connected to one of the brake circuits. The figure shows an example in which the pressure medium channel 62, the discharge 66 and the pressure medium conveying channel 68 are arranged immediately next to one another on the same side of the pressure generator 16.

[0021] Between the inlet, where the discharge 66 of the damping device leads into the second annular chamber 60b, and the outlet, where the pressure-medium-conveying passage 68 leaves the second annular chamber 60b, a throttle element 70 is arranged on the circumference of the piston pump. This throttle element 70 is located in a gap 72 or in a hollow space between the outer circumference of the liner 20 and the inner circumference of the pump receptacle 14. From a hydraulic perspective, the throttle element 70 is located downstream of the installation space 64 for the damping device cavity and upstream of the pressure-medium-conveying passage 68 of the pressure generator 16. The throttle element blocks a direct communication between the discharge 66 and the pressure-medium-conveying passage 68 and represents a flow resistance which counteracts the free flow of pressure medium from the throttle device cavity.

[0022] The throttle element 70 is exemplarily embodied as a closed annular disk with planar upper and lower surfaces that are parallel to one another. The outer and inner diameters of the annular disk are adapted to the size of the gap 72 between the liner 20 and the pump receptacle 14 in such a way that the throttle element 70 is received in the gap 72 so as to be movable in the direction of the longitudinal axis XX of the pressure generator 16. The upper surface of the throttle element 70 is located on the side of the liner 20 facing away from the packing ring 58, whereas the lower surface is arranged on the side of the packing ring 58.

[0023] The throttle element 70 consists of a resilient material, preferably spring steel or plastic.

[0024] The throttle element 70 rests with a peripheral edge region of its upper surface against a first support 74a, which is formed in the housing block 12 so as to lie against the wall of the pump receptacle 14 and extends radially into the pump receptacle 14, partially covering the throttle element 70 along its outer periphery. The first support 74a may extend along the entire inner periphery of the pump receptacle 14, i.e. forming a closed annular shoulder, or may comprise a number of ring segments, each spaced apart from the adjacent ring segments.

[0025] A second support 74b is formed on the liner 20, which also extends into the gap 72 between the liner 20 and the inner wall of the pump receptacle 14. This liner-side second support 74b extends along the inner diameter of the throttle element 70. The liner-side second support cooperates with the underside of the throttle element 70 and partially covers the edge area of ​​the throttle element 70 along its inner circumference. The throttle element 70 is thus arranged between the two supports 74a and 74b, or is held in position by the two supports 74a, 74b.

[0026] It should be pointed out that the disclosed arrangement of the second support 74b on the liner side on the underside of the throttle element 70 and the arrangement of the first support 74a on the hydraulic block side on the upper side of the throttle element 70 are merely exemplary. If necessary, the arrangement of the supports 74a,b may be interchanged.

[0027] The two supports 74a, 74b are spaced apart axially from one another in the direction of the longitudinal axis XX of the pressure generator 16. This distance is chosen to be smaller than the thickness of the throttle element 70, so that the throttle element 70 is concavely curved and rests with its inner or outer periphery, respectively, under axial pretension against the associated supports 74a or 74b. The supports 74a, 74b project, for example at right angles, from the associated circumferential wall, so that a line contact is created between the throttle element 70 and certain edges of the supports 74a, 74b within the gap 72.

[0028] The pressure medium flowing under pressure from the shock absorber installation space 64 into the second annular chamber 60b encounters the throttle element 70 and exerts a pressure on it. The effective pressure acts on the throttle element 70 in such a way that, on the one hand, it is pressed with its outer periphery against the first support 74a on the housing block side, and on the other hand, in the region of the inner diameter 70, it is moved away with its underside from the second support 74b on the liner side. The throttle cross section formed in this way depends on the pressure load in terms of its size. It increases as the pressure load increases or decreases again when the pressure load returns. Correspondingly, different volumes of pressure medium are discharged through the throttle cross section towards the pressure medium conveying channel 68, so that the pressure drop across the throttle element 70 changes accordingly.

[0029] Of course, modifications or supplements to the described embodiment are possible without departing from the invention as defined by claim 1. [Explanation of symbols]

[0030] 10 Hydraulic Unit 12 Housing Block 14 Pump receiving section 16 Pressure Generator 20 Liner 60a First annular chamber 60b Second annular chamber 64 Buffer installation space 68 Pressure medium conveying passage 70 Aperture elements 72 Gap 74a First support 74b Second Support

Claims

1. A housing block (12); a pressure generator (16) disposed within the pump receiving portion (14) of the housing block (12); a damping mechanism arranged downstream of the pressure generator (16) in the flow direction, the damping mechanism including a hydraulic cavity and a throttle element (70) arranged downstream of the hydraulic cavity, In a hydraulic unit (10), in particular for supplying a brake circuit of a vehicle brake system with pressure medium at brake pressure, the throttle element (70) is configured in the shape of a ring and is arranged in the housing block (12) in such a way that it is located around the periphery of the pressure generator (16) in a gap (72) between the pressure generator (16) and the associated pump receptacle (14), the throttle element (70) abuts at its upper surface against a first support (74a) and at its lower surface against a second support (74b) in a state where no pressure is applied thereto, and the supports (74a, 74b) are formed to face each other in the gap (72); The first support (74a) is formed on an inner wall of the pump receiving portion (14); A hydraulic unit, characterized in that the second support (74b) is formed on the periphery of the pressure generator (16), in particular on the periphery of a liner (20) of the pressure generator (16).

2. A housing block (12), a pressure generator (16) disposed within the pump receiving portion (14) of the housing block (12); a damping mechanism arranged downstream of the pressure generator (16) in the flow direction, the damping mechanism including a hydraulic cavity and a throttle element (70) arranged downstream of the hydraulic cavity, In a hydraulic unit (10), in particular for supplying a brake circuit of a vehicle brake system with pressure medium at brake pressure, the throttle element (70) is configured in the shape of a ring and is arranged in the housing block (12) in such a way that it is located around the periphery of the pressure generator (16) in a gap (72) between the pressure generator (16) and the associated pump receptacle (14), the throttle element (70) abuts at its upper surface against a first support (74a) and at its lower surface against a second support (74b) in a state where no pressure is applied thereto, and the supports (74a, 74b) are formed to face each other in the gap (72); The hydraulic unit is characterized in that the supports (74a, 74b) each protrude radially into the gap (72) and cover an edge region of the throttle element (70) along the inner or outer circumference of the throttle element (70), respectively.

3. A housing block (12), a pressure generator (16) disposed within the pump receiving portion (14) of the housing block (12); a damping mechanism arranged downstream of the pressure generator (16) in the flow direction, the damping mechanism including a hydraulic cavity and a throttle element (70) arranged downstream of the hydraulic cavity, In a hydraulic unit (10), in particular for supplying a brake circuit of a vehicle brake system with pressure medium at brake pressure, the throttle element (70) is configured in the shape of a ring and is arranged in the housing block (12) in such a way that it is located around the periphery of the pressure generator (16) in a gap (72) between the pressure generator (16) and the associated pump receptacle (14), the throttle element (70) abuts at its upper surface against a first support (74a) and at its lower surface against a second support (74b) in a state where no pressure is applied thereto, and the supports (74a, 74b) are formed to face each other in the gap (72); 1. A hydraulic unit comprising: a support body having a pump longitudinal axis and a throttle element, the support body being axially spaced apart from one another in the direction of the pump longitudinal axis, such that, when the pressure generator is installed in the pump receiving portion, the throttle element is arranged to be in a position parallel to the pump longitudinal axis and to be in a position parallel to the pump longitudinal axis.

4. A housing block (12), a pressure generator (16) disposed within the pump receiving portion (14) of the housing block (12); a damping mechanism arranged downstream of the pressure generator (16) in the flow direction, the damping mechanism including a hydraulic cavity and a throttle element (70) arranged downstream of the hydraulic cavity, In a hydraulic unit (10), in particular for supplying a brake circuit of a vehicle brake system with pressure medium at brake pressure, the throttle element (70) is configured in the shape of a ring and is arranged in the housing block (12) in such a way that it is located around the periphery of the pressure generator (16) in a gap (72) between the pressure generator (16) and the associated pump receptacle (14), the throttle element (70) abuts at its upper surface against a first support (74a) and at its lower surface against a second support (74b) in a state where no pressure is applied thereto, and the supports (74a, 74b) are formed to face each other in the gap (72); 1. A hydraulic unit comprising: a housing block having a pressure medium conveying passage for conveying a pressure medium to the pressure generator; a pressure medium conveying passage for conveying a pressure medium to the pressure generator;

5. A housing block (12), a pressure generator (16) disposed within the pump receiving portion (14) of the housing block (12); a damping mechanism arranged downstream of the pressure generator (16) in the flow direction, the damping mechanism including a hydraulic cavity and a throttle element (70) arranged downstream of the hydraulic cavity, In a hydraulic unit (10), in particular for supplying a brake circuit of a vehicle brake system with pressure medium at brake pressure, the throttle element (70) is configured in the shape of a ring and is arranged in the housing block (12) in such a way that it is located around the periphery of the pressure generator (16) in a gap (72) between the pressure generator (16) and the associated pump receptacle (14), the throttle element (70) abuts at its upper surface against a first support (74a) and at its lower surface against a second support (74b) in a state where no pressure is applied thereto, and the supports (74a, 74b) are formed to face each other in the gap (72); The hydraulic unit is characterized in that the hydraulic cavity of the shock absorber and the throttle element of the shock absorber are directly connected to associated annular chambers (60a, 60b) provided in the hydraulic unit (10), and the annular chambers (60a, 60b) are sealed from each other.

6. A hydraulic unit as described in any one of claims 1 to 5, characterized in that the throttling element (70) is configured to be elastic and / or is manufactured from an elastic material, in particular from spring steel or plastic.

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