Arrangement for throttling a fluid flow

Abstract

Arrangement for throttling a fluid flow with a throttling device (10A, 10B) comprising at least one first throttling point (16A, 16B) with a predetermined fixed opening cross-section and at least one second throttling point (18A, 18B) with a dynamic opening cross-section which is variably adjustable depending on a pressure difference, wherein the throttling device (10A, 10B) has a pot-shaped base body (12A, 12B) with a bottom (14A, 14B) on which the at least one second throttling point (18A, 18B) is formed, and a spring-loaded throttling element (20A, 20B) which determines the effective dynamic opening cross-section of the at least one second throttling point (18A, 18B), wherein the base body (12A, 12B) is axially fixed in an inlet bore (5.1) of a fluid channel (5) and is connected to a first bore shoulder (7) between the inlet bore (5.1) and outlet bore (5.2) of the fluid channel (5).

Description

State of the art

[0001] The invention relates to an arrangement for throttling a fluid flow.

[0002] Piston pumps are known in various designs from the prior art. For example, in ABS / ESP hydraulic units of vehicle brake systems, radial piston pumps with multiple pumping elements are often used to pump pressure fluids, with at least one piston being able to be moved back and forth by means of an eccentric. These so-called pumping elements typically consist of a piston, a piston running surface, often designed as a cylinder, inlet and outlet valves, and sealing elements. The valves serve to control the fluid during the pumping movement of the piston. The inlet valve prevents the fluid from flowing back into the intake chamber during the compression phase. The outlet valve prevents the fluid from flowing back from the pressure side into the pump interior and is typically housed in the pump cover.

[0003] The outflow geometry of the pump element influences the noise behavior of the ABS / ESP hydraulic unit and is therefore designed accordingly. This design is usually a suitable taper of the outflow channel, which then represents a throttling effect. This throttling effect creates a hydraulic low-pass filter, which has a positive effect on the noise. The behavior of the dynamic viscosity of the brake fluid in the range between 0° and 120°C can be considered almost constant and the optimal throttling effect is defined for this range. As a result of the large change in the kinematic viscosity of the brake fluid over the required temperature range of -40°C to 120°C, the throttle places a load on the pressure-loaded components of the pump elements and the entire pump drive, especially at low temperatures.The narrowed cross-section results in significantly increased fluid friction at low temperatures, leading to a significant increase in the pump's internal pressure and resulting stress. Therefore, modern systems use dynamic throttles that dynamically adjust the throttling effect depending on the differential pressure.

[0004] For example, published patent application DE 10 2011 079 876 A1 describes a piston pump for pumping fluids in a hydraulic vehicle brake system. The described piston pump comprises a cylinder, a piston movably mounted in the cylinder, and a pressure chamber arranged between an inlet valve and an outlet valve. The pressure chamber is enclosed by a cover. A throttle element designed as a resilient disc is provided downstream of the outlet valve to throttle the fluid flow. The resilient disc is incorporated into the cover, and centering means are provided in the cover to pre-center the throttle element in the cover.The described piston pump comprises a first throttle point with a passage released independently of the differential pressure, which has a defined constant flow cross-section, and a second throttle point with a passage released as a function of the differential pressure, which has a dynamic flow cross-section dependent on the differential pressure.

[0005] From the publication DE 196 20 975 B4, a power steering system for motor vehicles is known, comprising a steering gear, a hydraulic servomotor for assisting a steering torque introduced into the steering gear, and the following additional features: In the servomotor, two working chambers are separated from each other by a piston. A control valve for controlling a pressure medium delivered from a pressure source to and from the two working chambers of the servomotor is connected to the working chambers of the servomotor via two working lines. Damping valves are arranged between the working chambers and the control valve.The damping valves comprise a housing located between two pressure medium connections, with a flow channel connecting the two pressure medium connections, in which at least one point has a flow cross-section that is reduced compared to the cross-section of the pressure medium connections. The point with the reduced flow cross-section is formed by an orifice plate with a variable flow cross-section. The cross-section of the orifice plate can be changed by a flow between the two pressure medium connections in such a way that different cross-sections of the orifice plate can be created depending on the flow direction, the pressure, and the amount of pressure medium.

[0006] The documents DE 42 15 706 A1 and US 4,341,239 A each disclose an arrangement for throttling a fluid flow with a throttling device comprising at least one first throttling point with a predetermined fixed opening cross-section and at least one second throttling point with a dynamic opening cross-section that is variably adjustable depending on a pressure difference. The throttling device comprises a pot-shaped base body with a bottom on which the at least one second throttling point is formed, and a resilient throttling element that determines the effective dynamic opening cross-section of the at least one second throttling point. Disclosure of the invention

[0007] The arrangement according to the invention for throttling a fluid flow with the features of independent patent claim 1 can advantageously be manufactured simply and inexpensively.

[0008] Embodiments of the present invention provide an arrangement for throttling a fluid flow with a throttle device comprising at least one first throttle point with a predetermined fixed opening cross-section and at least one second throttle point with a dynamic opening cross-section that is variably adjustable depending on a pressure difference. The throttle device comprises a pot-shaped base body with a bottom, on which the at least one second throttle point is formed, and a resilient throttle element that determines the effective dynamic opening cross-section of the at least one second throttle point. The base body is axially fixed in an inflow bore of a fluid channel and bears against a first bore shoulder between the inflow bore and an outflow bore of the fluid channel.

[0009] The throttling device designed as a pot throttle with a dynamic throttling point and a static throttling point can advantageously be mounted as a single unit in the fluid channel or housing. The pot-shaped base body is inserted, for example, axially aligned into the bore of the fluid channel and pressed in until it stops and / or axially fixed in another suitable manner. The bore is designed, for example, with a bore shoulder, so that the base body can be pressed in until it stops. At low temperatures, the medium is advantageously backed up against the first throttling device, which acts as a fixed throttle. The resulting back pressure then slightly raises the second throttling device, so that negative effects on the pump drive can be reduced.Bending the throttle element results in a larger flow rate at high pressure and especially at low temperatures where the viscosity of the medium is high, so that the control current of the pump drive for conveying the medium can be positively influenced and advantageously reduced.

[0010] The measures and further developments listed in the dependent claims make advantageous improvements to the arrangement for throttling a fluid flow specified in independent patent claim 1 possible.

[0011] It is particularly advantageous that the base body can be pressed into an inflow bore of a fluid channel and can rest against a first bore shoulder between the inflow bore and an outflow bore of the fluid channel. The first bore shoulder advantageously simplifies the correct installation of the throttle device. The opening movement of the resilient throttle element can advantageously be limited by a stop, which can be designed as a second bore shoulder and can be arranged behind the first bore shoulder in the fluid channel in the flow direction. The second bore shoulder, which acts as a stop for the throttle element, advantageously prevents overexpansion of the throttle element under high pressure, so that no permanent deformation of the throttle element can occur.

[0012] In an advantageous embodiment of the arrangement according to the invention for throttling a fluid flow, the pot-shaped base body can be manufactured as a formed part and / or by machining. The dynamic pot throttle is preferably manufactured using a cost-effective deep-drawn part.

[0013] In a further advantageous embodiment of the arrangement according to the invention, the cup-shaped base body can be designed as a single piece with the resilient throttle element. The throttle element can be designed, for example, as a resilient tab in the cup base, wherein an area of ​​a gap formed between the resilient tab and the cup base in a rest position of the throttle element can represent the predetermined fixed opening cross-section of the at least one first throttle point. The resilient tab can be formed, for example, by fine blanking, laser cutting, etc. The resulting gap provides the desired constant throttle cross-section of a conventional fixed throttle.The throttle element, designed as a resilient tab, can be moved axially from its rest position towards the stop and back depending on the pressure difference between the inflow bore and the outflow bore, and can adjust the effective opening cross-section of the at least one second throttle point accordingly. The resilient tab creates the dynamic throttling effect by moving in the axial direction. The fluid channel is designed by the second bore shoulder so that a stop is provided for the resilient tab. During normal operation of the brake system and with normal brake fluid viscosity, the gap surface forms the constant opening cross-section for throttling. As pressure increases, the tab expands, releasing an increasingly larger flow cross-section. The tab expands until it comes to rest against the second bore shoulder, thereby preventing overstretching.

[0014] In an alternative advantageous embodiment of the arrangement according to the invention for throttling a fluid flow, the pot-shaped base body can have a guide pin on the bottom, onto which a throttle element designed as a spring washer can be pushed. The bottom with the guide pin can be compressed by a forming process and the throttle element designed as a spring washer can be axially fixed on a shoulder under preload. The at least one first throttle point can be designed as an opening in the region of the guide pin in the pot bottom, wherein an area of ​​the opening represents the predetermined fixed opening cross-section of the first throttle point. The at least one second throttle point can be designed as at least one opening in the pot bottom, which in a rest position can be completely covered by the throttle element designed as a spring washer.The throttle element designed as a spring washer can move axially from the rest position towards the stop and back depending on the pressure difference between the inflow bore and the outflow bore and can adjust the effective opening cross-section of the at least one second throttle point accordingly. The base body with the guide pin can be manufactured as a formed part or by machining. The openings for forming the first and second throttle points can be designed as bores and can be produced in a single operation during the manufacture of the base body. The spring washer is preferably designed as a stamped part and is pushed onto the closure pot pin. As pressure increases, the spring washer springs up until it comes to rest on the second bore shoulder and is thus prevented from overstretching.To prevent the spring washer from creating an undesirable sealing effect when pressed open at the bore shoulder, gaps or recesses can be provided on the outer circumference of the spring washer through which the medium can flow. When the pressure decreases, the spring washer springs back and seals again against the shoulder of the pot base.

[0015] Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. In the drawings, like reference numerals designate components or elements that perform the same or similar functions. Short description of the drawings Fig. 1 shows a schematic perspective partial sectional view of a first embodiment of an arrangement according to the invention for throttling a fluid flow. Fig. 2 shows a sectional view of the first embodiment of the arrangement according to the invention for throttling a fluid flow from Fig. 1. Fig. 3 shows a schematic perspective partial sectional view of a second embodiment of an arrangement according to the invention for throttling a fluid flow. Fig. 4 shows a sectional view of the second embodiment of the arrangement according to the invention for throttling a fluid flow from Fig. 3. Embodiments of the invention

[0016] As from Fig. As can be seen from Figures 1 to 4, the illustrated embodiments of an arrangement 1A, 1B according to the invention for throttling a fluid flow each comprise a throttling device 10A, 10B, which has at least one first throttling point 16A, 16B with a predetermined fixed opening cross-section and at least one second throttling point 18A, 18B with a dynamic opening cross-section that is variably adjustable depending on a pressure difference. The throttling device 10A, 10B has a pot-shaped base body 12A, 12B with a base 14A, 14B, on which the at least one second throttling point 18A, 18B is formed, and a resilient throttling element 20A, 20B, which determines the effective dynamic opening cross-section of the at least one second throttling point 18A, 18B.

[0017] As from Fig. 1 to 4, the base body 12A, 12B in the illustrated embodiments is pressed into an inflow bore 5.1 of a fluid channel 5 introduced into a fluid block or a housing 3 and rests against a first bore shoulder 7 between the inflow bore 5.1 and an outflow bore 5.2 of the fluid channel 5. Of course, the base body 12A, 12B can also be axially fixed in the inflow bore 5.1 in another suitable manner. The opening movement of the resilient throttle element 20A, 20B is limited by a stop, which is designed as a second bore shoulder 9 and is arranged behind the first bore shoulder 7 in the fluid channel 5 in the flow direction R. The throttle device 10A, 10B can advantageously be mounted as a structural unit in the fluid block or in the housing 3. The throttle device 10A, 10B is pressed axially into the inlet bore 5.1 of the fluid channel 5 until it stops. The supply bore 5.1 is formed by the first bore shoulder 7 so that the cup-shaped base body 12A, 12B of the throttle device 10A, 10B can be pressed in until it stops.

[0018] As from Fig. 1 and Fig. 2, the cup-shaped base body 12A in the first exemplary embodiment of the arrangement 1A according to the invention for throttling a fluid flow is designed as a single piece with the resilient throttle element 20A. In addition, the cup-shaped base body 12A is manufactured as a cost-effective deep-drawn part. The throttle element 20A in the first exemplary embodiment is designed as a resilient tab 22A in the cup base 14A. The base body 12A is mounted in a fluid channel 5, for example behind a damper volume. The resilient tab 22A can be formed by fine blanking, laser cutting, etc. The resulting gap corresponds in area to the predetermined fixed opening cross-section of the at least one first throttle point 16A.

[0019] The resilient tab 22A now generates the dynamic throttling effect by moving in the axial direction. The fluid channel 5 is formed by the second bore shoulder 9 in such a way that a stop is provided for the resilient tab 22A.

[0020] The second bore shoulder 9 serves to form a stop for the tab 22 to prevent overstretching of the tab 22A under high pressure and thus permanent deformation. During normal operation with normal viscosity, the gap cross-section forms the throttling. With increasing pressure, the tab 22A expands, thereby releasing an increasingly larger flow cross-section. The tab 22A expands until it rests against the second bore shoulder 9 and is thus protected from overstretching. At high pressure and especially at low temperatures, the bending causes a larger flow and thus positively influences the control current of a pump drive for conveying the medium. Fig. 2, the dashed representation of the tab 22A represents the stop position of the tab 22A with maximum stroke ds A or maximum flow cross-section.

[0021] As from Fig. 3 and Fig. 4, the pot-shaped base body 12B in the second exemplary embodiment of the arrangement 1B according to the invention for throttling a fluid flow has a guide pin 19.2B on the base 14B, onto which a throttling element 20B designed as a spring washer 22B with a guide opening 26B is pushed. The spring washer 22B is preferably designed as a stamped part and is pushed onto the guide pin 19.2B. The pot base 14B is then compressed with the guide pin 19.2B by a forming process, so that the spring washer 22B is fixed and secured. The spring washer 22B is pressed under prestress onto a shoulder 14.1B of the pot base 14B and fixed axially, so that the spring washer can seal at an outer edge 28B.

[0022] The pot-shaped base body 12B can be manufactured as a cost-effective formed part and / or by machining. The at least one first throttle point 16B is designed as an opening in the area of ​​the guide pin 19.1B in the pot base 14B, with an area of ​​the opening representing the predetermined fixed opening cross-section of the first throttle point 16B. Fig. In Figure 4, the dashed line and reference numeral 19.2B represent the guide pin before the forming of the base 14B, and reference numeral 19.1B represents the guide pin after the forming process. The at least one second throttle point 18B is designed as at least one opening in the pot base 14B, which, in a rest position, is completely covered by the throttle element 20B designed as a spring washer 22B. The openings in the pot base 14B can be produced as bores during the manufacture of the pot-shaped base body 12B in a single operation.

[0023] At low temperatures, the first throttle point 18B dams up the medium, and the resulting back pressure slightly lifts the outer edge 28B of the spring washer 22B. The spring washer 22B springs back until it rests against the second bore shoulder 9, thus preventing overstretching. To prevent an undesirable sealing effect of the spring washer 22B when pressed open against the second bore shoulder 9, the spring washer 22B has recesses 24B or interruptions on its outer circumference through which the medium can flow. The second bore shoulder 9 represents the stop position of the spring washer 22B and determines the maximum stroke ds. Bor the maximum flow cross-section of the second throttle point 18B. As the pressure decreases, the spring washer 22B springs back and seals again against the shoulder 14.1B on the pot bottom 14B. Bending the spring washer causes a larger flow of the medium at high pressure and especially at low temperatures where the viscosity of the medium is high.

[0024] Embodiments of the present invention provide a simple and cost-effective arrangement for throttling a fluid flow, which advantageously comprises a throttling device designed as a pot throttle with a dynamic throttling point and a static throttling point.

Claims

[1] Arrangement for throttling a fluid flow with a throttle device (10A, 10B) which comprises at least one first throttle point (16A, 16B) with a predetermined fixed opening cross-section and at least one second throttle point (18A, 18B) with a dynamic opening cross-section which is variably adjustable depending on a pressure difference, wherein the throttle device (10A, 10B) has a pot-shaped base body (12A, 12B) with a bottom (14A, 14B), on which the at least one second throttle point (18A, 18B) is formed, and a resilient throttle element (20A, 20B) which determines the effective dynamic opening cross-section of the at least one second throttle point (18A, 18B), wherein the base body (12A, 12B) is axially fixed in an inflow bore (5.1) of a fluid channel (5) and at a first Bore shoulder (7) between the inflow bore (5.1) and an outflow bore (5.2) of the fluid channel (5). [2] Arrangement according to claim 1, characterized by that the opening movement of the resilient throttle element (20A, 20B) is limited by a stop which is designed as a second bore shoulder (9) and is arranged in the flow direction (R) behind the first bore shoulder (7) in the fluid channel (5). [3] Arrangement according to claim 1 or 2, characterized by that the pot-shaped base body (12A, 12B) is produced as a formed part and / or by machining. [4] Arrangement according to one of claims 1 to 3, characterized by that the pot-shaped base body (12A, 12B) is designed in one piece with the resilient throttle element (20A, 20B). [5] Arrangement according to claim 4, characterized byin that the throttle element (20A) is designed as a resilient tab (22A) in the pot base (14A), wherein an area of ​​a gap which is formed between the resilient tab (22A) and the pot base (14A) in a rest position of the throttle element (20A) represents the predetermined fixed opening cross-section of the at least one first throttle point (16A). [6] Arrangement according to claim 4 or 5, characterized by that the throttle element (20A) designed as a resilient tab (22A) is movable axially from the rest position towards the stop and back depending on the pressure difference between the inflow bore (5.1) and the outflow bore (5.2) and adjusts the effective opening cross-section of the at least one second throttle point (18A) accordingly. [7] Arrangement according to one of claims 1 to 3, characterized bythat the pot-shaped base body (12B) has a guide pin (19.2B) on the bottom (14B), onto which a throttle element (20B) designed as a spring washer (22B) is pushed, wherein the bottom (14B) with the guide pin (19.1B) is compressed by a forming process and the throttle element (20B) designed as a spring washer (22B) is axially fixed under prestress on a shoulder (14.1B). [8] Arrangement according to claim 7, characterized by that the at least one first throttle point (16B) is designed as an opening in the region of the guide pin (19.1B) in the pot base (14B), wherein an area of ​​the opening represents the predetermined fixed opening cross-section of the first throttle point (16B). [9] Arrangement according to claim 7 or 8, characterized byin that the at least one second throttle point (18B) is designed as at least one opening in the pot base (14B), which in a rest position is completely covered by the throttle element (20B) designed as a spring washer (22B), wherein the throttle element (20B) designed as a spring washer (22B) is movable axially from the rest position in the direction of the stop and back depending on the pressure difference between the inflow bore (5.1) and the outflow bore (5.2) and adjusts the effective opening cross-section of the at least one second throttle point (18B) accordingly.

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