Hydraulic damping devices for damping pressure flow pulsations and pressure pulses in pressure medium flow within brake circuits of automotive brake control systems, and electronically slip-controllable brake equipment for automobiles having such hydraulic damping devices.

Abstract

To provide a hydraulic damping device for damping pumping flow pulsation and pressure pulse in particularly pressure medium flow in a brake circuit of an automobile brake system, and brake equipment capable of electronically slip-controlling for an automobile with this kind of hydraulic damping device.SOLUTION: A damping device (14) comprises a first damper (16) and at least one second damper (18). The dampers (16; 18) respectively have one hydraulic resistance element (20; 22) and hydraulic capacity (24; 26). Further, the dampers (16; 18) are connected in series with each other, and the hydraulic resistance elements (20; 22) and the hydraulic capacities (24; 26) are respectively located alternately and continuously in a flow direction R.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a hydraulic damping device for attenuating pumping flow pulsations and pressure pulses in the pressure medium flow in the brake circuit of a motor vehicle brake control system, particularly according to the features of claim 1. Furthermore, the present invention relates to an electronically slip-controllable brake installation for a motor vehicle having such a hydraulic damping device according to the features of claim 14.

Background Art

[0002] Brake control systems in motor vehicles are well-known. Brake control systems contribute to increasing safety in road traffic, as proven, and are therefore prescribed by law in many countries for the time being.

[0003] With this type of brake control system, the brake pressure of the vehicle wheel brakes can be electronically controlled so that wheel slip occurring at the assigned wheels of the vehicle occurs for at most a short time. In this way, the vehicle remains steerable during the braking process, does not fall into an unstable driving state during driving operation, and can still stop with a short braking distance. In addition to this, the brake control system can initiate the braking process autonomously, i.e., without the driver's involvement, in response to traffic situations at risk of an accident or dangerous driving states, and furthermore forms the basis for performing a piloted or automated driving operation.

[0004] The brake control system consists of a hydraulic assembly in which a pump or pressure generator and valves for generating and controlling the brake pressure for each wheel are arranged. The pump is operated by a motor attached to this hydraulic assembly and by an electronic control device that electrically drives the motor and the valves as needed.

[0005] Piston pumps are often used as pumps or pressure generators. These piston pumps are periodically operated by a rotationally driven eccentric body and pump a fluid pressure medium to the vehicle's wheel brakes via piping connected to a hydraulic manifold. This periodic pumping of the pressure medium has the drawback of subjecting the flow to pumping pulsations and pressure pulses. These pumping pulsations and pressure pulses occur in different frequency ranges and are transmitted into the passenger compartment via the piping connections leading to the pressure medium, which can be perceived as unpleasant noise by occupants.

[0006] Therefore, known brake control systems use damping devices to attenuate this type of pulsation and pulse. Known damping devices are incorporated into a hydraulic assembly together with a pressure generator and a valve. The damping device comprises a so-called damper consisting of a hydraulic capacity (hydraulische Kapazitaet) and a hydraulic resistance element. A certain amount of pressure medium is buffered in the hydraulic capacity while the hydraulic resistance element obstructs the unimpeded flow of pressure medium. Resistance elements that resist the pressure medium independently of the dominant pressure conditions, so-called static throttles, and resistance elements that resist variably depending on the pressure, so-called dynamic throttles, are known. Furthermore, both fixed-volume and pressure-dependent-variable-volume capacities are known. This type of variable-volume typically includes a medium separator that separates the pressure medium space from a damped space filled with a medium more compressible than the fluid pressure medium. This type of medium separator can be formed, for example, as an actuated piston or an elastically deformable membrane.

[0007] The arrangement of the damper in the brake control system and the components of the damper in the brake circuit of the brake control system is disclosed in Patent Document 1.

[0008] Essentially, attenuators have the disadvantage of taking up valuable space in the hydraulic assembly and, based on their structural design regarding size and / or elasticity, being limited to attenuating only pulsations or pressure pulses occurring within a narrow frequency range. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] German Patent Application Publication No. 102010040157 Specification [Overview of the Initiative]

[0010] In contrast, the hydraulic pressure damping device according to claim 1 has the advantage of smoothing the pressure flow pulsation of a periodically operating pressure generator and damping the pressure pulses in the amount of pressure medium being pumped.

[0011] While pumped flow pulsations are low-frequency (tief) or low-frequency excitations, pressure pulses have significantly higher excitation frequencies. This is because pressure pulses are caused by means of controlling the flow direction by the pump and occur "abruptly" when those means open or close. Pressure pulses result in a change of position of pressure medium particles from their stationary position within the pressure medium. In contrast, pumped flow pulsations follow a continuous transition due to fluctuations in the amount of pressure medium being pumped. Therefore, pumped flow pulsations depend on the rotational angle advanced by the motor shaft, or the contour of the cam or eccentric element positioned on this motor shaft used to operate the pressure generator.

[0012] According to the present invention, the above advantages are achieved in the proposed damping device by connecting two dampers, each having one hydraulic resistance and at least one hydraulic capacitance, in series with respect to each other, and by arranging these hydraulic resistances and capacitances alternately and continuously in the flow direction of the pressure medium. Preferably, the resistance elements and capacitances of the individual dampers are formed differently.

[0013] Other advantages or favorable forms of development of the present invention will become apparent from the dependent claims and / or the following description.

[0014] Dependent claims 2 to 7 relate to the hydraulic resistance of the provided attenuator. These dependent claims are directed to the structural form of the hydraulic resistance of the attenuator, its arrangement in the flow path, and the respective proportions of the total resistance of the hydraulic attenuator.

[0015] Dependent claims 8 to 13 claim details relating to the hydraulic capacity used in the attenuator. These dependent claims relate to the structural form of these capacities, their arrangement in the flow path, the magnitude setting of each amount of hydraulic capacity, and the proportion of each in the total volume of the attenuator.

[0016] As a result, the claimed measures provide an inexpensive and compact damping device that effectively attenuates low-frequency pressure flow pulsations and high-frequency pressure pulses in such a way that vehicle occupants do not perceive them as uncomfortable.

[0017] Claim 14 seeks protection of a local arrangement of damping devices according to claims 1 to 13 within the brake circuit of an electronically slip-controllable vehicle brake system.

[0018] Embodiments of the present invention are shown in the drawings and described in detail below. The drawings consist of two figures in total, and in these figures, the same elements are denoted by the same reference numerals for simplicity. [Brief explanation of the drawing]

[0019] [Figure 1] A diagram of the first embodiment of the present invention is shown. [Figure 2] A diagram of a second embodiment of the present invention is shown. [Modes for carrying out the invention]

[0020] Two embodiments are shown for hydraulic components in a part of a hydraulic circuit using circuit symbols. This part of the hydraulic circuit corresponds to a part of the brake circuit of an automotive brake control system.

[0021] The part shown in FIG. 1 of brake circuit 28 of an automotive brake control system extends between a drivable fluid pressure generator 10 and a wheel brake 12 to which a pressure medium under brake pressure is supplied by this pressure generator 10. The pressure generator 10 is a pressure generator that is driven periodically, and correspondingly this pressure generator pumps the pressure medium periodically, and in so doing generates a pumping flow that varies periodically between a minimum value and a maximum value when observed over time. This is the starting point. The resulting pumping flow variations occur in the relatively low-frequency range, or at low frequencies.

[0022] This pressure generator is preferably a piston pump actuated, for example, by a rotationally driven cam or eccentric. This type of piston pump has a pump control valve for controlling the flow direction through the pressure generator 10. This is usually a valve to which hydraulic pressure is applied, and this valve opens or closes substantially abruptly depending on the decrease in the pressure gradient in the controller. Correspondingly, these pump control valves generate relatively high-frequency pressure pulses in the pressure medium flow pumped in the brake circuit 28.

[0023] Between the pressure generator 10 and the wheel brake 12, a damping device 14 is arranged, exemplarily in the form of a secondary hydraulic low-pass. In principle, higher-order, i.e., third-order, fourth-order, or higher-order low-passes could also be provided.

[0024] The order of the low-pass filter indicates the number of attenuators in the attenuation device 14. Therefore, a second-order low-pass filter includes a first attenuator 16 and a second attenuator 18 each consisting of one hydraulic resistance element 20, 22 and hydraulic capacitances 24, 26. In the embodiment of FIG. 1, downstream of the pressure generator 10, first, the first hydraulic resistance element 20 of the first attenuator 16 is arranged. The first hydraulic capacitance 24 of the first attenuator 16 follows this first hydraulic resistance element in the flow direction R of the pressure medium. The second hydraulic resistance element 22 follows this first hydraulic capacitance, and finally, the second hydraulic capacitance 26 of the second attenuator 18 follows. Therefore, the attenuators 16, 18 are connected in series with each other, and the assigned resistance elements 20, 22 and capacitances 24, 26 are continuous alternately. Further, the resistance elements 20, 22 and the capacitances 24, 26 are each formed with structural differences.

[0025] The first hydraulic resistance element 20 of the first attenuator 16 is a resistance element having a constant throttle cross-section or a static throttle. The size of the throttle cross-section of this throttle is constant and does not depend on the dominant pressure situation. The first resistance element 20 may be formed as a reduced-diameter section in an existing pressure medium pipeline as required, or may be composed of a throttle sleeve with a predetermined throttle cross-section installed in the pressure medium pipeline.

[0026] The first hydraulic capacitance 24 arranged after the first hydraulic resistance element 20 of the first attenuator 16 includes a medium separator 30 and accordingly has a pressure medium storage capacity that depends on the pressure situation. The pressure medium storage capacity increases with an increase in the pressure of the pressure medium. As the medium separator 30, for example, an elastic membrane that separates a pressure medium chamber from a damping chamber filled with a compressible gas, or a spring elastic component such as a spring and / or a piston that is pressurized by an elastomeric body and slidably accommodated in a cylinder has been found to be suitable.

[0027] Downstream of the first hydraulic capacity 24 of the first attenuator 16, a second hydraulic resistance element 22 with variable hydraulic resistance is positioned in the flow path. This type of resistance element has a flow cross-section whose size is variable depending on the dominant pressure conditions and is therefore also called a dynamic throttle. In this type of resistance element, the flow cross-section increases with increasing pressure difference.

[0028] Finally, between the dynamic throttle and the wheel brake 12 is the second hydraulic capacity 26 of the second damper 18. This second hydraulic capacity 26 has a constant pressure medium capacity and can be formed, in particular simply, as an extension of the cross-section of an existing pressure medium conduit, or as a separate hollow body that is in hydraulic contact with this pressure medium conduit.

[0029] The hydraulic resistance elements 20, 22 and hydraulic capacities 24, 26 of each damper 16, 18 are structurally coordinated with respect to their damping effect within the illustrated brake circuit or hydraulic circuit 28. This coordination is based on the following regularity: The total hydraulic flow resistance within the brake or hydraulic circuit 28, consisting of two resistance elements 20 and 22, is 100%. This total flow resistance is generated by approximately 5% to 15% by the first resistance element 20 located after the pressure generator 10, i.e., the static throttle, and approximately 85% to 95% by the second resistance element 22, which faces the wheel brake 12, and therefore the dynamic throttle. In contrast, the total hydraulic capacity of the two dampers 16 and 18 within the hydraulic circuit 28 has an inverse relationship. This means that the variable pressure medium capacity of the first hydraulic capacity 24 of the first damper 16, located on the pump side of the total capacity, determines approximately 85% to 95% of the 100% of the damper 14, while the pressure medium capacity of the second hydraulic capacity 26 of the second damper 18, located on the wheel brake side, determines approximately 5% to 10%.

[0030] The above design rules also apply to the second embodiment of the present invention shown in Figure 2.

[0031] This embodiment differs from the first embodiment shown in Figure 1 in that the hydraulic capacity 24 of the first attenuator 16 is located immediately after the pressure generator 10, followed by the hydraulic resistance element 22, then the second hydraulic capacity 26 of the second attenuator 18, followed finally by the hydraulic resistance element 20, and finally the flowing pressure medium merges with the wheel brake 12. Therefore, in the second embodiment, the damping device 14 differs from the first embodiment shown in Figure 1, starting with the hydraulic capacity 24 and ending with the hydraulic resistance element 20. However, what the two embodiments have in common is that the hydraulic resistance element 22 between the two hydraulic capacities 24 and 26 of the attenuators 16 and 18 is formed as a resistance element with a variable flow cross-section, i.e., a dynamic throttle, and upstream of this dynamic throttle is the first hydraulic capacity 24 having a pressure-dependent variable pressure medium capacity. In other words, in the second embodiment, the hydraulic resistance element 20 with a constant flow cross-section is moved from the inlet to the outlet of the damping device 14.

[0032] Naturally, modifications or additions other than those described in the above embodiments are possible without departing from the scope of protection of the present invention as defined by the claims. [Explanation of Symbols]

[0033] 10. Pressure generator 12-wheel brakes 14 Damping device 16 Attenuator 18 Attenuator 20 Hydraulic resistance elements 22 Hydraulic resistance element 24. Hydraulic capacity 26. Hydraulic capacity 28 Hydraulic circuits, brake circuits 30 media separators

Claims

1. A hydraulic damping device (14) for damping pressure flow pulsations and pressure pulses in a pressure medium flow within a brake circuit (28) of an automobile brake control system, comprising a first damping device (16) and at least one second damping device (18), The first attenuator (16) and the second attenuator (18) each have one hydraulic capacity (24; 26) for buffering the amount of pressure medium, The brake circuit (28) has hydraulic resistance elements (20; 22) that obstruct the flow of pressure medium without obstruction, The first attenuator (16) and the second attenuator (18) are connected in series with each other. The hydraulic capacity elements (24; 26) and the hydraulic resistance elements (20; 22) are arranged alternately and continuously in the flow direction (R) of the pressure medium, At least one of the hydraulic resistance elements (20; 22) has a flow cross-section whose size is variable depending on the pressure, At least one of the hydraulic resistance elements (20; 22) of the first attenuator (16) and the second attenuator (18) has a large flow cross section whose size is constant with respect to pressure, A hydraulic damping device is provided in the brake circuit (28) where the hydraulic resistance element (20), which has a large flow cross section whose size is constant with respect to pressure, is positioned directly toward the pressure generator (10) or the wheel brake (12).

2. The hydraulic damping device according to claim 1, characterized in that the hydraulic resistance element (22), which has a flow cross section whose size is variable depending on the pressure, is arranged between the hydraulic capacities (24; 26) of each of the dampers (16; 18).

3. The hydraulic damping device according to claim 1 or 2, characterized in that at least the hydraulic resistance elements (20; 22) of the first damper (16) and the second damper (18) make individual contributions of different magnitudes to the total flow resistance of the hydraulic damping device (14), and the individual contributions of each hydraulic resistance element are adjusted to each other such that the individual contribution of one of the hydraulic resistance elements (20) is about 5% to 15% of the total flow resistance, and accordingly the individual contribution of the other hydraulic resistance element (22) is about 85% to 95%.

4. The hydraulic damping device according to claim 3, characterized in that the flow resistance of the hydraulic resistance element (20), which has a flow cross-section whose magnitude is constant depending on the pressure, is about 5% to 15% of the total flow resistance of the first damper (16) and the second damper (18).

5. A hydraulic attenuation device according to any one of claims 1 to 4, wherein at least one of the hydraulic capacities (24; 26) of the first attenuator (16) and the second attenuator (18) is provided with a medium separator (30), and the medium separator separates the amount of pressure medium from the amount of attenuation containing a medium with a higher compressibility than the pressure medium.

6. The hydraulic pressure damping device according to claim 5, characterized in that the medium with the higher compressibility is a gas.

7. At least one of the hydraulic capacities (24; 26) of the first attenuator (16) and the second attenuator (18) is equipped with a media separator (30), A hydraulic attenuation device according to any one of claims 1 to 6, characterized in that the hydraulic capacity (24) of the first attenuator (16) equipped with the medium separator (30) is located upstream of the hydraulic capacity (26) of the second attenuator (18).

8. A hydraulic pressure attenuation device according to any one of claims 1 to 7, characterized in that one of the hydraulic pressure capacities (24, 26) of the first attenuator (16) and the second attenuator (18) that attenuates the pressure medium has an amount whose magnitude is constant depending on the pressure.

9. The hydraulic attenuation device according to any one of claims 1 to 8, characterized in that the individual amounts of the hydraulic capacities (24; 26) of at least the first attenuator (16) and the second attenuator (18) are adjusted to each other such that one of the hydraulic capacities (26) is about 5% to 15% of the total amount of the hydraulic attenuation device (14), while the other hydraulic capacities (24) is accordingly about 85% to 95% of the total amount.

10. The individual amounts of the hydraulic capacities (24; 26) of at least the first attenuator (16) and the second attenuator (18) are adjusted such that one of the hydraulic capacities (26) is about 5% to 15% of the total amount of the hydraulic attenuation device (14), while the other hydraulic capacities (24) is adjusted accordingly to be about 85% to 95% of the total amount. The hydraulic pressure damping device according to any one of claims 5 to 7, characterized in that the hydraulic pressure capacity (24) equipped with the media separator (30) is about 85% to 95% of the total amount.

11. An electronically slip-controllable brake system for an automobile, comprising a brake circuit (28) in which an electronically controllable and driveable pressure generator (10) is arranged to pressurize a pressure medium to a wheel brake (12) under brake pressure, the pressure generator (10) periodically pressurizes the pressure medium in the flow direction (R), A brake system comprising a hydraulic pressure damping device (14) for damping pressure flow pulsations and pressure pulses in the brake circuit (28) according to any one of claims 1 to 10, A brake system characterized in that the hydraulic damping device (14) is located downstream of the pressure generator (10) and upstream of the wheel brake (12) in the brake circuit (28).

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