Device for Choking a Fluid Flow and Corresponding Piston Pump for Delivering Fluids

Abstract

A device for choking a fluid flow includes a pot-like base body, in the base of which a first passage opening is arranged, and a closing body guided axially moveably in the pot-like base body against a spring force of a spring element and having a second passage opening that forms a static choke point with a predefined fixed opening cross section. The closing body in combination with the spring element and the first passage opening forms a dynamic choke point with a dynamic opening cross section that is variably adjustable depending on a pressure difference.

Claims

1. A device for choking a fluid flow, comprising: a pot-like base body including a base having a first passage opening; a spring element; a closing body guided axially moveably in the pot-like base body against a spring force of the spring element and having a second passage opening configured to form a static choke point with a predefined fixed opening cross section; and a delay device configured to delay a closing movement of the closing body in a targeted fashion, the delay device including the spring element, wherein the closing body in combination with the spring element and the first passage opening forms a dynamic choke point with a dynamic opening cross section that is variably adjustable depending on a pressure difference, and wherein the spring element is configured as an elastomer spring.

2. The device according to claim 1, wherein the delay of the closing movement of the closing body is predefined by at least one of a choice of material of the elastomer spring and a geometry for the elastomer spring.

3. A piston pump for delivering fluids, comprising: a piston; a pump cylinder; a pressure chamber arranged between an inlet valve and an outlet valve; and a device for choking a fluid flow, the device located downstream of the outlet valve in the fluid flow, the device including (i) a pot-like base body including a base having a first passage opening, (ii) a spring element, (iii) a closing body guided axially moveably in the pot-like base body against a spring force of the spring element and having a second passage opening configured to form a static choke point with a predefined fixed opening cross section, and (iv) a delay device configured to delay a closing movement of the closing body in a targeted fashion, the delay device including the spring element, wherein the closing body in combination with the spring element and the first passage opening forms a dynamic choke point with a dynamic opening cross section that is variably adjustable depending on a pressure difference, and wherein the spring element is configured as an elastomer spring.

4. The piston pump according to claim 3, wherein the delay of the closing movement of the closing body is predefined by at least one of a choice of material of the elastomer spring and a geometry for the elastomer spring.

5. The piston pump according to claim 4, wherein the delay device is configured such that in a first operating mode of the piston pump, the static choke point is disabled after a predefined number of pump strokes and bridged by a bypass formed by the dynamic choke point.

6. The piston pump according to claim 5, wherein the delay device is configured such that in a second operating mode, the static choke point is enabled and causes a pressure-independent choking of the fluid flow.

7. The piston pump according to claim 6, wherein the piston pump has a higher flow rate in the first operating mode and a lower flow rate in the second operating mode.

8. The piston pump according to claim 3, wherein a longitudinal axis of the elastomer spring is coaxial with the second passage opening.

9. The piston pump according to claim 8, wherein the elastomer spring is configured to compress along the longitudinal axis to move the closing body away from the first passage opening.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 shows a diagrammatic cross-section view of an extract of a first exemplary embodiment of a piston pump according to the disclosure for delivering fluids, with a first exemplary embodiment of a device according to the disclosure for choking a fluid flow.

[0014] FIG. 2 shows a diagrammatic detailed drawing of the piston pump according to the disclosure for delivering fluids from FIG. 1.

[0015] FIG. 3 shows a diagrammatic cross-section view of an extract of a second exemplary embodiment of a piston pump according to the disclosure for delivering fluids, with a second exemplary embodiment of a device according to the disclosure for choking a fluid flow.

[0016] FIG. 4 shows a force-travel curve of a device according to the disclosure for choking a fluid flow from FIG. 1 or FIG. 3.

[0017] FIG. 5 shows a flow-pressure difference curve of a device according to the disclosure for choking a fluid flow from FIG. 1 or FIG. 3, on the first stroke of the corresponding piston pump.

[0018] FIG. 6 shows a flow-pressure difference curve of a device according to the disclosure for choking a fluid flow from FIG. 1 or FIG. 3, on a second stroke of the corresponding piston pump.

[0019] FIG. 7 shows a flow-pressure difference curve of a device according to the disclosure for choking a fluid flow from FIG. 1 or FIG. 3, after the third stroke of the corresponding piston pump.

DETAILED DESCRIPTION

[0020] As evident from FIGS. 1 to 3, the exemplary embodiments shown of a device 10, 10A according to the disclosure for choking a fluid flow comprise a pot-like base body 14, in the base of which a first passage opening 14.1 is arranged, and a closing body 16, 16A guided axially moveably in the pot-like base body 14 against the spring force of a spring element 18, 18A and having a second passage opening 16.1 that forms a static choke point 11 with a predefined fixed opening cross section. The closing body 16, 16A in combination with the spring element 18, 18A and the first passage opening 14.1 here forms a dynamic choke point 12, 12A with a dynamic opening cross section which is variably adjustable depending on a pressure difference. According to the disclosure, a delay device 20, 20A is provided which delays the closing movement of the closing body 16, 16A in a targeted fashion.

[0021] Embodiments of the choke device 10, 10A of a fluid flow according to the disclosure are used in the exemplary embodiments shown in a piston pump 1, 1A for delivering fluids which comprises a piston, a pump cylinder 5 and a pressure chamber arranged between an inlet valve and an outlet valve. The pressure device 10, 10A is here arranged in the fluid flow downstream of the outlet valve of the piston pump 1, 1A. The pump cylinder 5 in the exemplary embodiment shown is inserted in a receiver bore of a fluid block 3 with corresponding fluid channels 3.1, 3.2. The delay device 20, 20A of the choke device 10, 10A is configured such that in a first operating mode of the piston pump 1, 1A, which is characterized by a higher flow rate and high engine speeds, the static choke point 11 is disabled after a predefined number of pump strokes and is bridged by a bypass formed by the dynamic choke point 12, 12A. Also, the delay device 20, 20A is configured such that in a second operating mode of the piston pump 1, 1A, which is characterized by a lower flow rate and low engine speeds, the static choke point 11 is enabled and causes a pressure-independent choking of the fluid flow.

[0022] To be able to achieve as high a flow rate as possible, the initially static choke point 11 is disabled as far as possible on each pump stroke. For good NVH performance however, precisely this static choke point 11 is very important for choking the fluid flow at low engine speeds at which noise-critical maneuvers are normally carried out. At low engine speeds, the integrated inertia according to the disclosure does not affect the closing behavior of the choke device 10, 10A. The pump strokes at low engine speeds are too far apart and the dynamic choke point 12 can close despite the integrated inertia. At high engine speeds, if a high flow rate is required, the dynamic choke point 12 can no longer close since the integrated inertia is too high and the dynamic choke point 12 can no longer close in the short time available. In this way, a direct bypass is created and the static choke point 11 is disabled.

[0023] As further evident from FIGS. 1 and 2, in the first exemplary embodiment shown of the choke device 10 according to the disclosure, the delay device 20 comprises a friction element 22 with a lip 22.1 which is arranged between the closing body 16 and an inner wall 14.2 of the pot-like base body 14 and creates a direction-dependent friction. In the first exemplary embodiment shown, the friction element 22 is thus arranged in a receiver 24 in the closing body 16 which is formed as a peripheral groove, such that the lip 22.1 of the friction element 22 is guided on the inner wall 14.2 of the pot-like base body 14. Due to the lip 22.1 formed, the friction element 22 has a lower friction value in the opening direction of the closing body 16 than in the closing direction of the closing body 16. Thus the friction element 22 has a higher friction value in the closing direction than in the opening direction. In an alternative exemplary embodiment not shown, the closing body 16 is configured as a plastic injection molding on which the friction element 22 is directly molded.

[0024] As further evident from FIG. 3, in the second exemplary embodiment shown of the choke device 10A according to the disclosure, the delay device 20A comprises a spring element 18A formed as an elastomer spring 22A. The delay in the closing movement of the closing body 16A can be predefined simply by suitable choice of material and/or geometry of the elastomer spring 22A.

[0025] As further evident from FIG. 4, the integrated friction element 22 in the first exemplary embodiment, or the elastomer spring 22 used in the second exemplary embodiment, causes the depicted hysteresis of the force-travel curve of the choke device 10, 10A according to the disclosure.

[0026] As further evident from FIG. 5, the first flow-differential pressure curve H1 shown, representing a first pump stroke at high flow rate, has a clear static proportion at lower pressure differences.

[0027] As further evident from FIG. 6, the second flow-differential pressure curve H2 shown, representing a second pump stroke at high flow rate, has a smaller static proportion at low pressure differences, which has almost completely disappeared in the third flow-differential pressure curve H3 shown in FIG. 7, representing a third pump stroke at high flow rate. The course of the flow-differential pressure curves for subsequent pump strokes corresponds to the course of the third flow-differential pressure curve H3 shown.