Damping device, in particular for damping pressure pulsations in a brake circuit of a slip-controlled vehicle braking system

Abstract

Damping device (10), in particular for damping pressure pulsations in a brake circuit of a slip-controlled vehicle braking system, comprising: a pressure medium reservoir (14) with variable pressure medium volume and a throttling device (16) that restricts the outflow of pressure medium from the pressure medium reservoir (14), with a base body (20) forming a throttle cross-section (22), a closing element (24) controlling the throttle cross-section (22) depending on the prevailing pressure conditions and with a restoring element (28) clamped between a first support (30a) on the base body (20) and a second support (30b) on the closing element (24) and acting on the closing element (24) with a restoring force in the direction of the throttle cross-section (22), characterized in that that, at least in the non-flowing state of the throttle device (16), the return element (28) is supported on the base body (20) and / or on the closing element (24) at an angle of inclination (36) to a longitudinal axis L of the throttle device (16) that deviates from 90°, that the restoring element (28) acts on the closing element (24) with a resulting total force, which is composed of an axial force component and a radial force component, wherein the closing element (24) performs a tilting movement due to the effective radial force component when lifting off from the throttle cross-section (22).

Description

Disclosure of the invention Prior art

[0001] The invention relates to a damping device, in particular for damping pressure pulsations in a brake circuit of a slip-controlled vehicle braking system.

[0002] Modern vehicle braking systems are often equipped with electronic brake pressure control, for example, to assist the driver in critical driving situations and / or to prevent vehicle instability. Such braking systems are capable of building up or regulating brake pressure at one or more wheel brakes, even if the driver has no intention of braking or has not even pressed the brake pedal. To build up brake pressure in the vehicle's brake circuits, at least one piston pump is usually provided, which is indirectly actuated by an electronically controlled motor via a driven cam or eccentric. Piston pumps are readily available and inexpensive, but due to their operating principle, they have the disadvantage of delivering hydraulic fluid cyclically rather than continuously.A cyclical flow of hydraulic fluid generates pressure pulsations that propagate into the brake circuits and are perceptible inside the vehicle as undesirable operating noise. The damping elements underlying the invention are used to reduce these pressure pulsations and to even out the pressure build-up in the wheel brakes.

[0003] Damping devices, such as those made of Fig. The devices known from DE 10 2011 089 183 A1 comprise a pressure medium reservoir with a variable pressure medium volume and a throttling device that restricts the outflow of pressure medium from the pressure medium reservoir. To achieve a satisfactory damping effect at low pump flow rates, i.e., at low pump motor speeds, a high flow resistance of the throttling device is necessary in addition to a high storage capacity of the pressure medium reservoir.

[0004] On the other hand, high flow resistance is a disadvantage in highly dynamic control maneuvers, i.e., when large quantities of pressure medium are required per unit of time and the drive speed of the pump drive is correspondingly high, because it puts a mechanical strain on the pump drive and reduces the speed and the delivery volume.

[0005] Throttle devices are therefore often designed as valves capable of controlling the throttle cross-section depending on the prevailing pressure conditions. Such throttle devices comprise a base body that forms the throttle cross-section and a closing element that controls this cross-section in a pressure-dependent manner. The closing element interacts with an elastic return element, which applies a mechanical return force to the closing element in the opposite direction of flow through the throttle device.

[0006] Such throttling devices are known, for example, from JP 2015 - 55 170 A or from DE 100 59 382 A1.

[0007] A disadvantage of this type of throttle design is that, when the throttle cross-section is open, the closing element is surrounded by the flow of fluid and centered by the pressure medium flow in the outflow cross-section. Centering forces on the closing element cause it to vibrate, which in turn results in volume flow fluctuations, pressure pulsations, and ultimately undesirable operating noise.

[0008] Against this background, the object of the present invention is to reduce the operating noise of a throttling device or to improve throttling devices with regard to the vibration tendency of their closing elements. This object is achieved by a throttling device according to the features of claim 1. Advantages of the invention

[0009] The invention according to the features of claim 1 has the advantage that the closing element is less strongly excited to vibrations and that a throttling device according to the invention consequently does not generate any operating noise perceptible in the interior of the vehicle. This effect is achieved by radial forces acting transversely to the flow direction through the throttling device and decentering the closing element. The stroke movement of the closing element is no longer caused solely by the axial forces acting in the flow direction through the throttling device, but by a resulting total force on the closing element, which is composed of an axial force component and a radial force component. According to the invention, the radial force component is of mechanical origin and thus advantageously does not depend on the flow conditions such as, for example, the temperature or the viscosity of the hydraulic fluid.Due to the effective radial force, the closing element, when lifted from the throttle cross-section, performs a lateral deflection or tilting movement and is subjected to asymmetrical flow around its circumference. This means that a different amount of pressure medium flows past one circumferential segment of the closing element per unit of time than past any other circumferential segment. The radial force component on the closing element is generated by an elastic restoring element, which acts on the closing element against the flow direction of the throttle. This restoring element is supported on at least one support, which, according to the invention, is inclined at an angle to the longitudinal axis of the throttle that deviates from 90°, or in other words, forms an angle of inclination with the longitudinal axis of the throttle that deviates from 90°.

[0010] Further advantages or advantageous developments of the invention will become apparent from the dependent claims or from the following description.

[0011] Particularly cost-effective elastic return elements are coil springs, which are especially easy to arrange on the side of the closing element facing away from the throttle cross-section and exert a compressive force on the closing element. Alternatively, tension springs, disc springs, or deformable elastomer spring elements are conceivable, as well as spring assemblies in parallel or series connection.

[0012] An advantageous further development of the invention is one in which the mechanically generated radial force component on the closing element is supported or amplified by a flow-induced radial force component. Flow-induced radial force components require asymmetrically designed closing elements and / or throttle cross-sections, which cause a correspondingly asymmetrical flow of pressure medium around the closing element. For example, grooves aligned coaxially to the longitudinal axis of the throttle device can be provided on a limited circumferential section of the closing element and / or the throttle cross-section, and / or wing-shaped projections can be provided on the closing element and / or throttle cross-section. drawing

[0013] An embodiment of the invention is shown in the drawing and is described in detail in the following description.

[0014] They show: Fig. 1: the circuit symbol of a damping device underlying the invention and known from the prior art; Fig. 2: a throttling device designed according to the invention of this damping device in the closed, non-flowing state and Fig. 3: the throttle device according to Fig. 2 in the open state, through which pressure medium flows. Description of an exemplary embodiment

[0015] Fig. Figure 1 shows the basic structure of a damping device 10 using circuit symbols. This device is connected to the pressure side of a driven piston pump 12 and comprises a pressure medium reservoir 14 and a throttle device 16 arranged downstream of this pressure medium reservoir 14, the cross-sectional area of ​​which can be varied. The pressure medium reservoir 14 can be designed, for example, as a piston, bellows, or diaphragm reservoir. It has an elastic and / or spring-loaded separating element inside, which separates a pressure medium-filled chamber from a gas-filled chamber. The pressure medium chamber has a variable volume; the gas-filled chamber can alternatively be connected to the atmosphere.

[0016] The throttling device 16 restricts the outflow of pressure medium from the pressure medium chamber of the pressure medium reservoir into a pressure medium-carrying line 18 of a pressure medium circuit (not shown) and thus acts as a flow resistance. For this purpose, the throttling device 16 has a throttle cross-section whose flow rate varies depending on the pressure level prevailing in the line 18. At lower pressures, a smaller throttle cross-section is established than at higher pressures.

[0017] For example, such throttling devices 16 can be designed in the form of spring-loaded check valves.

[0018] The one in Fig. Figure 2 of the throttling device 16, designed according to the invention, is shown in its closed position and is therefore not permeated by pressure medium in this position. It consists of a base body 20 with the throttle cross-section 22 formed thereon and a closing element 24 that controls the throttle cross-section 22. The throttle cross-section 22 is enclosed by a valve seat 26 designed as an internal cone. The closing element 24 rests against the valve seat 26 with a dome-shaped first end and closes off the throttle cross-section 22 against flowing pressure medium. For this purpose, the closing element 24 interacts with an elastic return element 28, for example implemented in the form of a coil spring. The opening pressure at which the closing element 24 lifts off from the valve seat 26 and releases the throttle cross-section 22 to flowing pressure medium can be determined by the stiffness of this return element 28.The return element 28 is arranged on the side of the closing member 24 facing away from the flow and is clamped between a first support 30a formed on the base body 20 and a second support 30b formed on the closing member 24.

[0019] The pressure medium flows according to Fig. 2 from below the throttle device 16, as illustrated by the flow direction arrow S. The flow direction arrow S runs coaxially to a longitudinal axis L of the throttle device 16. The closing element 24 is therefore subjected by the restoring element 28 to a restoring force acting against the flow direction through the throttle device 16.

[0020] For example, the closing element 24 has a cylindrical cross-section. Its diameter is smaller than the diameter of an outflow channel 32, which connects downstream to the valve seat 26 of the base body 20. Accordingly, the closing element 24 is movably guided with circumferential clearance in the outflow channel 32 and, when the throttle cross-section 22 is open, is surrounded by the outflowing pressure medium. Due to its lateral clearance, the closing element 24 can perform a certain lateral or tilting movement in the outflow channel 32, as described in Fig. 3 is shown.

[0021] According to the invention, at least one of the supports 30a, 30b for the return element 28 is inclined relative to the longitudinal axis L of the throttling device 16 (flow direction arrow S) at an angle of inclination 36 that deviates from 90°. If the support 30b formed on the closing member 24 is involved, the aforementioned angle of inclination 36 is measurable when the closing member 24 assumes the closed position and seals off the throttle cross-section 22 against incoming pressure medium. The magnitude of the angle of inclination 36, which deviates from 90°, can be selected according to the specific application.

[0022] Alternatively, it is conceivable to design the support 30a formed on the base body 20, or both supports 30a and 30b together, to be inclined. In the latter case, an inclination in the same or opposite direction is possible. The figures show an exemplary embodiment of the invention in which only the support 30b formed on the closing element 24 is inclined relative to the longitudinal axis L of the throttling device 16, while the second support 30a on the base body is oriented perpendicular to the longitudinal axis L of the throttling device 16. The claimed invention is expressly not limited to this embodiment.

[0023] Due to the inclination of the support 30b deviating from 90°, the restoring element 28 arranged between the supports 30a and 30b is prestressed to varying degrees along its circumferential direction, thereby exerting an axial force component F on the closing member 24 acting against the flow direction. A and secondly, with a radial force component F acting perpendicular to the direction of flow R acts ( Fig. 3). F A and F R Together, they produce the restoring force F acting on the closing element 24. As a result of the radial force component F R The locking element 24 leads to a Fig. The tilting movement shown in Figure 3 about its center of gravity occurs as soon as it lifts off the valve seat 26 and exposes the throttle cross-section 22. This is the case as soon as the pressure force of the incoming pressure medium on the closing element 24 is greater than the axial force component F acting in the closing direction. Aof the return element. Due to the tilting movement of the closing element 24 within the outflow channel 32, a gap that was originally annular in shape between the outer circumference of the closing element 24 and the wall of the outflow channel 32 now has an asymmetrical cross-section, i.e., a cross-section that changes in dimensions along the circumferential direction. Consequently, different circumferential sections of the closing element 24 are subjected to varying flow intensities per unit of time. Due to this asymmetrical flow, additional flow-induced radial forces act on the closing element 24, which increase the mechanical radial force component F provided by the return element 28. R reinforce and contribute to ensuring that the closing element 24 maintains its tilted position even when exposed to airflow. A closing element 24 exposed to asymmetrical airflow is less prone to pulsations and noise-generating vibrations than a closing element 24 exposed to symmetrical airflow.

[0024] An asymmetrical flow of pressure medium around the closing element 24 can further be supported by design measures on the closing element 24 and / or on the outflow channel 32. According to the Fig. 2 and Fig. In the embodiment shown in Figure 3, a groove 34 is formed on a circumferential section of the closing element 24, which extends, at least in the non-tilted state of the closing element 24, largely coaxially to the flow direction or to the longitudinal axis L of the throttling device. Alternatively, it is possible to provide several such grooves 34. These grooves 34 are only to be arranged on a limited circumferential section of the closing element 24; a remaining second circumferential section of the closing element 24 has no grooves 34.

[0025] The grooves 34 are permeable to the pressure medium and thus reduce the flow resistance in the area of ​​the circumferential section provided with the grooves 34 compared to the flow resistance in the area of ​​the groove-free circumferential section. Consequently, different pressure conditions and thus a pressure difference arise at the various circumferential sections of the closing element 24, which ultimately also generates a radial force F. RThe effect on the closing element 24 is flow-induced. In principle, wing-shaped projections on the closing element 24, aligned in the direction of the longitudinal axis L of the throttling device 16, could also be conceivable to influence or direct the flow around it in order to generate flow-induced radial forces. Wing-shaped projections and flow-through grooves 34 can be provided individually or in combination on the closing element 24, on the wall of the outflow channel 32, or both on the closing element 24 and on the wall of the outflow channel 32. By selecting the number, shape, and / or dimensions of the grooves 34 or the projections, their flow-directing effect and thus the magnitude of the radial force F acting on the closing element 24 can be adjusted. R determine.

[0026] Of course, further modifications or additions are conceivable without deviating from the basic idea of ​​the invention.

Claims

[1] Damping device (10), in particular for damping pressure pulsations in a brake circuit of a slip-controlled vehicle braking system, comprising: a pressure medium reservoir (14) with variable pressure medium volume and a throttling device (16) that restricts the outflow of pressure medium from the pressure medium reservoir (14), with a base body (20) forming a throttle cross-section (22), a closing element (24) controlling the throttle cross-section (22) depending on the prevailing pressure conditions and a restoring element (28) clamped between a first support (30a) on the base body (20) and a second support (30b) on the closing element (24) and acting on the closing element (24) in the direction of the throttle cross-section (22) with a restoring force, characterized by , that, at least in the non-flowing state of the throttle device (16), the return element (28) is supported on the base body (20) and / or on the closing element (24) at an angle of inclination (36) to a longitudinal axis L of the throttle device (16) that deviates from 90°, that the restoring element (28) acts on the closing element (24) with a resulting total force, which is composed of an axial force component and a radial force component, wherein the closing element (24) performs a tilting movement due to the effective radial force component when lifting off from the throttle cross-section (22). [2] Damping device according to claim 1, characterized by , that the elastic restoring element (28) is a spring, in particular a coil spring, which acts on the closing member (24) with a restoring compressive force. [3] Damping device according to claim 1 or 2, characterized by, that means (34) are formed at an end of the closing member (24) facing the throttle cross-section (22) and / or on a circumferential side of the closing member (24), which cause an asymmetric flow around the closing member (24) with pressure medium when the throttle cross-section (22) is open. [4] Damping device according to claim 3, characterized by that the flow-influencing means comprise at least one groove (34) through which pressure medium can flow.

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