Pump element, in particular for delivering hydraulic pressure medium in a brake circuit of an electronically slip-controllable brake system of a motor vehicle

Abstract

The invention relates to a pump element (10), in particular for delivering hydraulic pressure medium in a brake circuit of an electronically slip-controllable brake system of a motor vehicle. Known pump elements (10) have a pump cylinder (12) in which is arranged a pump piston (14) drivable for reciprocal motion. With the pump cylinder (12), the pump piston (14) defines a pump working chamber (16), which a pressure medium flows into under the control of an inlet valve (20) and flows out of under the control of an outlet valve (22). The outlet valve (22) comprises an outlet valve sealing seat (34) and an outlet valve closing member (24) which interacts therewith and is actuated by an outlet valve spring (86). The invention proposes an outlet valve (22) having a seat contour (28) comprising two mutually concentric tapered bores (30; 32) which have differing taper angles and merge into one another, wherein the outlet valve sealing seat (34) interacting with the outlet valve closing member (24) is formed at a first tapered bore (30), which has a more acute taper angle than a second tapered bore (32).

Description

[0001] Disclosure of the invention

[0002] title

[0003] Pump element, in particular for conveying hydraulic pressure medium in a brake circuit of an electronically controlled brake system of a motor vehicle

[0004] State of the art

[0005] The invention relates to a pump element, in particular for conveying hydraulic pressure fluid in a brake circuit of an electronically controlled brake system of a motor vehicle according to the features of the preamble of claim 1. Such a pump element is known, for example, from Figure 1 of DE 10 2014 212 292 A1.

[0006] In this known pump element, the outlet valve comprises a steel ball, which is pressed against an outlet valve seat by a coil spring. The outlet valve seat is designed as a conical seat and has a seat contour formed by a single conical bore. At its narrowest point, this conical seat transitions into a cylindrical passage, which in turn opens into a pump work chamber. Downstream of the conical seat, the pressure medium is discharged via a housing component with an annular channel and radial channels branching off from it into a brake circuit, which is in contact with the pump element.

[0007] Against this background, the object underlying the invention is to further develop the known pump element and to improve it with regard to its delivery capacity, noise development during operation, service life and reliability and, moreover, to reduce the costs for material and production of the pump element.

[0008] Advantages of the invention

[0009] According to the characterizing features of claim 1, a pump element for achieving the above-mentioned object has an outlet valve with a seat contour of two conical bores which are concentric with one another and merge into one another and have different conical angles, wherein an outlet valve sealing seat for the outlet valve closing member is arranged on a first conical bore which has a more acute conical angle than the second conical bore.

[0010] The seat contour of the outlet valve limits the radial vibration of the outlet valve closing element, thus contributing to noise reduction and lowering the operating noise of the pump element. Inevitably occurring pressure oscillations have smaller amplitudes, which prevents wear on the outlet valve and increases the service life and reliability of the pump element and its components.

[0011] Further advantages or advantageous developments of the invention emerge from the subclaims and / or from the following description.

[0012] The design of the outlet valve closing element is adapted to the seat contour of the outlet valve in such a way that the pump element can deliver high volume flows with low wear even at low temperatures.

[0013] The design of an exhaust valve closing element improves its axial guidance during its opening or closing movement within the seat contour and also ensures centering of the elastic exhaust valve spring relative to the exhaust valve closing element. Furthermore, a stroke limiter is created.

[0014] A recess, notch, groove, or similar feature at the transition from the center section to the spring support of the valve closure element ensures deliberate leakage when the exhaust valve is closed, should the valve closure element be accidentally installed incorrectly, i.e., with the second end section facing the sealing seat. By measuring the leakage during production, incorrect assembly can be easily identified and assembly quality improved.

[0015] Furthermore, the outlet valve is protected from foreign particles and the associated wear by a filter screen arranged immediately upstream of the outlet valve. By using a filter screen arranged in a pump work chamber, a ring filter known from the prior art upstream of the inlet valve is no longer necessary, and pressure losses caused by such a ring filter are avoided. The filter screen is designed as a flat plate and is therefore inexpensive. Instead of the known ring filter, a frame-shaped ring support element is used, which has a plurality of open passage windows for pressure medium along its circumference. Open passage windows have a negligible throttling effect on the pressure medium flowing through.Finally, the seat contour and a wall of a housing component, which accommodates the outlet valve closing element and its associated outlet valve spring, create a flow cross-section within the pump element through which the pressure medium flows out of the pump element in a defined manner. The pressure medium flows around the outlet valve closing element in such a way that optimal opening and closing behavior of the outlet valve closing element is achieved, noise generation is reduced, and the service life of the pump element is increased.

[0016] drawing

[0017] Embodiments of the invention are illustrated in the drawing and are explained in detail in the following description.

[0018] The drawing comprises a total of 6 figures in which corresponding components are provided with identical reference numbers.

[0019] Fig. 1 is a perspective view of a first embodiment of a pump element according to the invention in longitudinal section;

[0020] Fig. 2 is a perspective view of a second embodiment of a pump element according to the invention in longitudinal section;

[0021] Fig. 3 is a perspective view of a ring support element as a single part;

[0022] Fig. 4 is a perspective view of a filter screen as an individual part;

[0023] Fig. 5 is a perspective view of a valve closing element as a single part and

[0024] Fig. 6 is a perspective view of a housing component as an individual part.

[0025] Description of the embodiments

[0026] Fig. 1 :

[0027] The pump element (10) shown here consists of a pump cylinder (12), a pump piston (14) which is movably received in this pump cylinder (12) and can be driven to a periodic, i.e. in the figure up and down, stroke movement, a pump working chamber (16) delimited by the pump cylinder (12) and the pump piston (14), a piston return element (18) arranged in the pump working chamber (16), an inlet valve (20) for controlling the inflow of a pressure medium into the pump working chamber (16) and an outlet valve (22) for controlling the outflow of the pressure medium from the pump working chamber (16).

[0028] The pump cylinder (12) consists of a sleeve body closed on one side by a cylinder base (12a) with a circumferential cylindrical shaft (12b) surrounding the pump working chamber (16), the inner wall of which provides axial and radial guidance for the pump piston (14). In the center of the cylinder base (12a), a passage (26) is formed, closed by an outlet valve closing element (24). The outlet valve (22) is designed as a seat valve and has a seat contour (28) which, viewed in the flow direction of the pressure medium, adjoins this passage (26) downstream. According to the invention, this seat contour (28) is formed by two conical bores (30, 32) which are concentric with one another and merge into one another and have conical angles of different sizes, wherein an outlet valve sealing seat (34) for the outlet valve closing member (24) is arranged on a first conical bore (30) facing the passage (26).This first conical bore (30) has a more acute conical angle than the second conical bore (32) following downstream.

[0029] Immediately upstream of the outlet valve (22), a filter screen (36) is arranged inside the pump working chamber (16). This filter screen protects the downstream outlet valve (22) from particles and / or other contaminants from the pressure medium and thus contributes to trouble-free and low-wear operation of the pump element (10) or its outlet valve (22). The filter screen (36) used is plate-shaped and preferably has a largely circular outer shape. It has a plurality of through-openings (38) for the pressure medium. These through-openings (38) can optionally be designed with a circular opening cross-section or with any desired free-form cross-section.By selecting the material for the filter screen (36), the material thickness, the number of existing through-openings (38), the opening contour of these through-openings (38), the total opening cross-section and the hole spacing between the through-openings (38), the filtering effect of the filter screen (36) can be adjusted to suit the application, without adversely affecting the flow coefficient of the pump element (10).

[0030] In the illustrated embodiment, the pump piston (14) is constructed in two parts and consists of a solid-cylindrical first piston part (40) located outside the pump working chamber (16) and a hollow-cylindrical second piston part (42) that extends at least partially into this pump working chamber (16). A receiving area is formed on the second piston part (42) into which the first piston part (40) extends partially and rests flush with its end face against a step of this second piston part (42).

[0031] The second piston part (42) has a plurality of radial bores (44) which open into an axial bore (46) extending through the second piston part (42). The end of the axial bore (46) facing the pump working chamber (16) forms an inlet valve seat (48) of the inlet valve (20) of the pump element (10). The latter is controlled by an inlet valve member (50), which in this embodiment of the invention is designed as a ball and is urged against the inlet valve seat (48) by an inlet valve spring (52). The inlet valve spring (52) is a spiral spring, the end of which facing away from the inlet valve member (50) is supported on a valve cage (54). This valve cage (54) projects into the pump working chamber (16) and is fixed by one of its ends to the second piston part (42).The valve cage (54) has circumferential through-openings (56) through which pressure medium enters the pump working chamber (16) when the inlet valve member (50) is lifted from the inlet valve seat (48) due to the prevailing pressure conditions, counter to the force of the inlet valve spring (52). Furthermore, a circumferential shoulder (58) is formed at the piston-side end of the valve cage (54), against which one end of the piston return element (18) rests. This shoulder (58) forms a circumferential sealing lip, by which the pump working chamber (16) or the guide of the pump piston (14) in the pump cylinder (12) is sealed from the outside.

[0032] The section of the pump element (10) protruding from the pump cylinder (12) is surrounded by a frame-shaped annular support element (60). The latter is fastened in an axial extension to the open end of the pump cylinder (12). This annular support element (60) is preferably a plastic part with two opposite ends, each designed as a ring (62, 64; Fig. 3), which is connected by longitudinal struts (66) to form a one-piece, rigid component. The longitudinal struts (66) are arranged at a mutual distance from one another along the circumference of the annular support element (60) and define open passage windows (68; Fig. 3) between them, through which a pressure medium can flow from the outside, largely unthrottled, to the inlet valve (20) of the pump element (10).The upper ring (62) of the ring support element (60), facing away from the pump cylinder (12), guides the first piston part (40) of the pump piston (14) and, for this purpose, has internal dimensions that are matched to the external dimensions of this first piston part (40). Furthermore, the upper ring (62) carries a shaped sealing ring (70) arranged outside the ring support element (60). This shaped sealing ring (70) seals a guide gap between the outer circumference of the pump piston (14) and the inner diameter of an associated pump receptacle of a pump housing.

[0033] The outlet valve closing member (24) is a rotationally symmetrical component with a central section (72; Fig.5) and two end sections (74, 76; Fig.5) formed in one piece and projecting axially outwards from this central section (72) in opposite spatial directions.

[0034] The first end portion (74) of the outlet valve member (24) interacts with the outlet valve sealing seat (34) of the seat contour (28). This first end portion (74) has an ellipsoidal longitudinal section.

[0035] A plurality of projections (78) or prongs project axially outward from the first end section (74) in the longitudinal axis direction of the outlet valve closing member (24). Their outer flanks lie within an imaginary circle with a diameter corresponding to the diameter of the passage (26) in the cylinder base (12a) of the pump cylinder (12). The projections (78) guide the outlet valve closing member (24) axially in the passage (26) of the pump cylinder (12) during its opening or closing movement. The pressure medium flows between the projections (78) and out of the pump working chamber (16) along the circumference of the first end section (74) of the outlet valve closing member (24).

[0036] A second end section (76; Fig. 5) of the exhaust valve closing member (24) is, for example, cone-shaped, with a cylindrical base (80) and a truncated cone (82) that tapers outwardly. A transition from the cylindrical base (80) of the second end section (76) to the central section (72) forms a rectangular shoulder extending along the outer circumference, which provides a spring support (84) for an exhaust valve spring (86) of the exhaust valve. The exhaust valve spring (86) and the exhaust valve closing member (24) are centered relative to one another by means of the cylindrical base (80).

[0037] At least one recess (88; Fig. 5), in particular a notch, groove, or the like, extending in the direction of the longitudinal axis of the outlet valve closing member (24) is formed on the circumference of the outlet valve closing member (24) at a transition from the central section (72) to the spring support (84) of the second end section (76). If the outlet valve closing member (24) is accidentally mounted incorrectly, this recess (88) causes a measurable leak when the outlet valve (22) is not actuated, which allows for easy detection of the incorrect assembly or monitoring of the assembly quality.

[0038] The outlet valve spring (86) is supported with its end facing away from the pump element (10) in a receptacle (90) of a housing component (92). On an end face of this housing component (92) facing the pump cylinder (12), there is a wall (94) that projects axially in the direction of the longitudinal axis of a pump element (10) and encloses the receptacle (90) for the outlet valve spring (86). This wall (94) is surrounded radially outwardly by a groove-shaped annular channel (96) that is open toward the pump cylinder (12) and opens into at least one radial channel (98; Fig. 6) of the housing component (92).The projecting wall (94) of the housing component (92) lies opposite a bore wall of the second conical bore (32) of the pump cylinder (12) at an axial distance, whereby a flow cross-section (100) is established between the two walls, through which pressure medium flowing out of the pump working chamber (16) reaches the annular channel (96) and further into the radial channel (98) or flows out of the pump element (10). Fig. 2 shows a second embodiment of a pump element according to the invention, which differs from the first embodiment in that at least the inlet valve closing member (50) is identical to the outlet valve closing member (24).

[0039] Accordingly, both valve closing members (24; 50) are designed as rotationally symmetrical components with a central section (72) and two end sections (74; 76) formed integrally thereon and projecting axially in opposite spatial directions from this central section (72).

[0040] For design details of the valve closing elements (24; 50), reference is made to the relevant explanations in Fig.1 in order to avoid repetition.

[0041] Fig. 3 shows the ring support element (60) already mentioned in connection with the description of Fig. 1 in a perspective view as a single part. As mentioned, this ring support element (60) is preferably a plastic body with opposite ends formed as rings (62; 64). These rings (62; 64) are connected to one another by longitudinal struts (66) distributed around the circumference, forming a one-piece, rigid component.

[0042] The annular support element (60) holds the pump element (10) or the pump cylinder (12) and the pump piston (14) together with the inlet valve (20) and the piston return element (18) as an assembly. According to the invention, the annular support element (60) has a plurality of open passage windows (68) on its circumference, through which pressure medium can flow to the inlet valve (20) largely unhindered and which thus reduce the pressure loss coefficient of the pump element (10) or enable flow through it with low pressure loss. The number and structural details of these longitudinal struts (66) determine the delivery capacity of the pump element (10).

[0043] Fig. 4 shows the filter screen (36) arranged immediately upstream of the outlet valve (22) in the pump element (10) as an individual part. This filter screen (36) is clearly designed as a flat plate which preferably has a thickness of at least 0.05 mm and a maximum of 0.50 mm. The filter screen (36) can in principle be represented with any desired outer contour; the illustration shows an at least approximately circular shape. A filter screen (36) with an outer diameter of between 0.5 mm and 12.0 mm is recommended. The filter screen (36) has a defined number of through-openings (38) for the pressure medium. These through-openings (38) can also have any desired contour, but are preferably circular and have a diameter of between 0.02 mm and 1.0 mm. The minimum hole spacing between two through-openings (38) is between 0.01 mm and 1.00 mm.These geometric conditions, combined with the material strength of the filter screen (36), the viscosity of the pressure medium, the peak flow rate of the pump element (10), and the dimensions of the expected foreign particles, result in an optimum balance of pressure loss and strength. The filter screen (36) protects the outlet valve (22) from foreign particles, thereby increasing the reliability and reducing the risk of failure of the pump element (10) or the outlet valve (22).

[0044] Fig. 5 illustrates the valve closing element (24; 50) of an exhaust or inlet valve as a single part. The valve closing element (24; 50) shown is a nearly rotationally symmetrical body with a central section (72) and two end sections (74; 76) projecting axially outward on opposite sides of this central section (72). The central section (72) has an outer diameter of between 1.0 mm and 8.0 mm; overall, the valve closing element (24; 50) has an axial length of between 2.0 mm and 10.0 mm. The outer circumference of the central section (72) forms a contact surface with a wall of a receptacle (90) in a housing component (92). A first end section (74) with an ellipsoidal and thus spherical longitudinal section adjoins the central section (72). When the outlet valve (22) is closed, this first end section (74) seals the outlet valve seat (34).At least three and a maximum of seven projections (78) project axially outward from the first end section (74). Their outer flanks on the circumference of the valve closure element (24; 50) lie within the imaginary outer diameter with a dimension between 1.0 mm and 8.0 mm. The extension length of the projections (78) is a minimum of 0.2 mm and a maximum of 10.0 mm.

[0045] The second end section (76) of the valve closure member (24; 50), opposite the first end section (74), forms a spring support (84) for the piston return element (18). This spring support (84) is formed by a circumferential, rectangular shoulder surrounding a pin-shaped core consisting of a cylindrical base (80) and a truncated cone (82). The piston return element (18) and the valve closure member (24; 50) are centered relative to one another by means of the cylindrical base (80).

[0046] The second end section (76) can have any desired contour, for example, cylindrical, conical, spherical, or even with webs. Furthermore, it can be intentionally longer in the longitudinal direction of the valve closing member (24; 50) than a block length of the piston return element (18) in order to protect the latter from damage under operating conditions. At the transition from the spring support (84) to the central section (72), there is a local recess (88), which can be designed, for example, as a groove, notch, or the like. This recess (88) can have any desired free form and causes leakage if the valve closing member (24; 50) is inadvertently mounted incorrectly and the spring support (84) is facing the valve seat (34).

[0047] Leakage measurement during assembly of a pump element (10) thus allows incorrectly assembled components to be identified and eliminated. The valve closing elements (24; 50) can, in principle, be made of any material, with the lowest possible mass of a valve closing element offering advantages with regard to opening and closing behavior.

[0048] Fig. 6:

[0049] The valve closing member (24) of the outlet valve (22), including the associated outlet valve spring (86), is accommodated in a receptacle (90) of a housing component (92), which is shown in this figure. The viewer looks at an end face of the housing component (92) facing the pump cylinder (12) and recognizes a circumferentially continuous wall (94) which is surrounded by an annular channel (96). The wall (94), together with the second conical bore (32) of the seat contour (28) on the pump cylinder (12), creates a defined gap or flow cross-section (100) through which the pressure medium enters the annular channel (96) in a defined manner. A radial channel (98) opens out at least on one side of the annular channel (96).

[0050] The flow cross-section (100), the seat contour (28), the annular channel (96), and the at least one radial channel (98) are structurally coordinated with one another such that the pressure medium flow around the valve closure member (24) generates a defined opening and / or closing movement of the same. This reduces the noise generated by the pump element (10) and increases its service life.

[0051] Of course, changes or advantageous developments of the described embodiments are possible without departing from the scope of protection specified by the following claims.

Claims

Claims 1. Pump element (10), in particular for conveying hydraulic pressure medium in a brake circuit of an electronically slip-controllable brake system of a motor vehicle, comprising a pump cylinder (12), a pump piston (14) which is slidably guided in the pump cylinder (12) and can be driven to perform a periodic reciprocating movement, a pump working chamber (16) delimited by the pump cylinder (12) and pump piston (1), an inlet valve (20) for controlling pressure medium flowing into the pump working chamber (16), and an outlet valve (22) for controlling pressure medium flowing out of the pump working chamber (16), wherein the outlet valve (22) comprises an outlet valve sealing seat (34) and an outlet valve closing member (24) interacting with this outlet valve sealing seat (34), characterized in that the outlet valve (22) has a seat contour (28) made up of two conical bores (30;32) with different cone angles, wherein the outlet valve sealing seat (34) is arranged on a first cone bore (30) which has a more acute cone angle than a second cone bore (32); 2. Pump element according to claim 1, characterized in that the outlet valve closing member (24) has a central portion (72) and two end portions (74; 76) arranged on opposite sides of the central portion (72) and each projecting outwardly from the central portion (72).

3. Pump element according to claim 2, characterized in that a first end section (74) associated with the outlet valve sealing seat (34) has an ellipsoidally shaped longitudinal section and that a second end section (76) has a circumferential spring support (84) for an outlet valve spring (86).

4. Pump element according to claim 2 or 3, characterized in that at least 3 projections (78) project outwards in the axial direction from the first end section (74) and that the projections (78) engage in a passage (26) of the pump cylinder (12) adjacent to the seat contour (28) for axial guidance of the outlet valve closing member (24).

5. Pump element according to claim 3 or 4, characterized in that an extension length of the second end portion (74) in the direction of the longitudinal axis of the outlet valve closing member (24) is greater than a block length of the outlet valve spring (86).

6. Pump element according to one of claims 3 to 5, characterized in that at least one depression, in particular a notch or groove, extending in the direction of the longitudinal axis of the outlet valve closing member (24) is formed on the circumference of the outlet valve closing member (24) at a transition from the central section (72) to the spring support (84).

7. Pump element according to one of claims 1 to 6, characterized in that a filter screen (36) is arranged in the pump working chamber (16) immediately upstream of the outlet valve (22).

8. Pump element according to one of claims 3 to 7, characterized in that the outlet valve closing member (24) with the outlet valve spring (86) are accommodated in a receptacle (90) of a housing component (92), wherein the housing component (92) has, on an end face facing the pump cylinder (12), a wall (94) enclosing the receptacle (90), which wall is surrounded radially on the outside by an annular channel (96) into which a radial channel (98) opens.

9. Pump element according to claim 8, characterized in that an end face of the wall (94) of the housing component (92) with a bore wall of the second conical bore (32) forms a flow cross-section (100) through which pressure medium flowing out of the outlet valve (22) enters the annular channel (96) of the housing component (92).

10. Pump element according to one of claims 1 to 8, characterized in that the pump element (10) has a frame-shaped annular support element (60) whose opposite ends are formed into rings (62; 64) which are connected by longitudinal struts (66) to form a one-piece component, wherein the longitudinal struts (66) are arranged along the circumference of the annular support element (60) at a mutual distance such that between each two longitudinal struts (66) there is an open passage window (68) through which pressure medium can flow.

Images