Pump element for pumping a hydraulic pressure medium, particularly in the brake circuit of an electronically slip-controllable braking system in an automobile.

Abstract

The present invention relates in particular to a pump element (10) for pumping a hydraulic pressure medium in the brake circuit of an electronically slip-controllable brake system of an automobile. A known pump element (10) has a pump cylinder (12) in which a pump piston (14) is disposed to be driven to perform a stroke motion. The pump piston (14) together with the pump cylinder (12) defines a pump working chamber (16) into which a pressure medium flows in under control by an inlet valve (20) and out of the pump working chamber under control by an outlet valve (22). The outlet valve (22) includes an outlet valve seal seat (34) and an outlet valve closing member (24) which cooperates with the outlet valve seal seat and is operated by an outlet valve spring (86). An outflow valve (22) has been proposed, which has a seat contour (28) consisting of two conical holes (30;32) with different sizes of conical angles that are concentric and transitional with respect to each other, in which case the outflow valve seal seat (34) which cooperates with the outflow valve closing member (24) is formed in the first conical hole (30) which has a sharper conical angle than the second conical hole (32).

Description

Technical Field

[0001] Background Art The present invention relates to a pump element for pumping hydraulic pressure medium in a brake circuit of an electronically slip-controllable brake device, particularly for motor vehicles, according to the precharacterizing features of claim 1. Such a pump element is known, for example, from Figure 1 of German Patent Application Publication No. 102014212292.

[0002] In this known pump element, the outlet valve comprises a steel ball which is loaded by a coil spring and pressed against an outlet valve seat. The outlet valve seat is formed as a conical seat and has a seat contour formed by a separate conical bore. This conical seat transitions into a cylindrical flow passage at its narrowest point, and the flow passage itself opens into the pump working chamber. Downstream of the conical seat, the pressure medium is led out through a casing component provided with an annular passage and a radial passage branching from the annular passage, to the brake circuit in contact with the pump element.

[0003] Against this background, the object underlying the present invention is to improve such a known pump element in terms of its pumping output, noise generation during operation, service life and reliability, and further to reduce the costs related to the material and manufacturing of the pump element.

[0004] Advantages of the Invention According to the features recited in the characterizing portion of claim 1, in order to solve the above problem, the pump element has an outlet valve provided with a seat contour consisting of two conical bores with different taper angles which are concentric with each other and transition into one another, wherein the outlet valve sealing seat for the outlet valve closing member is arranged in the first conical bore that has an acute taper angle smaller than that of the second conical bore.

[0005] The seat contour of the outlet valve limits radial vibration of the outlet valve closing member, thereby contributing to noise reduction or a decrease in operating noise of the pump element. The resulting pressure vibrations have a smaller amplitude, which avoids wear in the outlet valve and increases the service life and reliability of the pump element or its components.

[0006] Further advantages or advantageous forms of the present invention will become apparent from the dependent claims and / or the following description.

[0007] The outlet valve closing member is structurally adjusted to match the contour of the outlet valve seat so that it can pump high volume flow with low wear even at low temperatures using the pump element.

[0008] The configuration of the outlet valve closing member improves the axial guidance of the outlet valve closing member during its opening or closing motion within the seat contour, and further centers the elastic outlet valve spring relative to the outlet valve closing member. In addition, stroke limiting is achieved.

[0009] If the valve closing member is assembled incorrectly, i.e., with its second end portion facing the seal seat, a recess, notch, groove, or similar feature in the transition from the central portion of the valve closing member to the spring support portion will cause intentional leakage when the outlet valve is closed. This allows for easy detection of misassembly based on leakage measurements during manufacturing, thereby improving assembly quality.

[0010] Furthermore, the outlet valve is protected from foreign particles and the resulting wear by a filter screen located immediately upstream of the outlet valve. The filter screen located within the pump working chamber eliminates the need for a conventionally known ring filter upstream of the inlet valve, thereby avoiding pressure loss caused by such a ring filter. The filter screen is formed as a flat plate and is therefore inexpensive to produce. Instead of a known ring filter, a frame-like ring support element is used, which has multiple open passage windows along its circumferential surface for the pressure medium. The open passage windows have only a negligibly slight throttling effect on the passing pressure medium.

[0011] Finally, the seat contour and the walls of the casing components housing the outlet valve closing member and the outlet valve spring positioned corresponding to the outlet valve closing member form a flow cross-section inside the pump element, through which the pressure medium is defined and flows out of the pump element. In this case, the pressure medium flows around the outlet valve closing member so that optimal opening and closing behavior of the outlet valve closing member is achieved, noise generation is reduced, and the service life of the pump element is extended.

[0012] Embodiments of the present invention are shown in the drawings and described in detail below. The drawings consist of a total of six figures, and corresponding components in the drawings are given a unified reference numeral. [Brief explanation of the drawing]

[0013] [Figure 1] This is a perspective longitudinal cross-sectional view showing a first embodiment of the pump element according to the present invention. [Figure 2] This is a perspective longitudinal cross-sectional view showing a second embodiment of the pump element according to the present invention. [Figure 3] This is a perspective view showing the ring support element as an individual component. [Figure 4] This is a perspective view showing the filter screen as an individual component. [Figure 5] This is a perspective view showing the valve closing member as an individual component. [Figure 6] This is a perspective view showing the casing components as individual parts.

[0014] Description of the Examples Figure 1: The pump element (10) shown herein comprises a pump cylinder (12), a pump piston (14) movably housed within the pump cylinder (12) and driveable to perform periodic, i.e., upward and downward stroke movements in the drawing, a pump working chamber (16) defined by the pump cylinder (12) and the pump piston (14), a piston return element (18) positioned within the pump working chamber (16), an inlet valve (20) that controls the inflow of a pressure medium into the pump working chamber (16), and an outlet valve (22) that controls the outflow of a pressure medium from the pump working chamber (16). The pump cylinder (12) consists of a sleeve body with a surrounding cylinder shaft (12b) that is closed on one side by a cylinder bottom (12a), the cylinder shaft surrounding the pump working chamber (16), and its inner wall guiding the pump piston (14) in the axial and radial directions. A passage (26) is formed at the center of the cylinder bottom (12a), which is closed by an outflow valve closing member (24). The outflow valve (22) is formed as a seat valve and has a seat contour (28), which continues downstream of the passage (26) when viewed in the flow direction of the pressure medium. According to the present invention, the seat contour (28) is formed by two conical holes (30, 32) that are concentric with each other and transition toward each other, and have different conical angles, in which case the outflow valve seal seat (34) for the outflow valve closing member (24) is located in the first conical hole (30) facing the passage (26). This first conical hole (30) has a sharper conical angle than the second conical hole (32) that continues downstream.

[0015] Immediately upstream of the outlet valve (22), a filter screen (36) is positioned inside the pump working chamber (16). This filter screen protects the downstream outlet valve (22) from particles and / or other impurities from the pressurized medium, thereby contributing to the smooth, low-wear operation of the pump element (10) or its outlet valve (22). The inserted filter screen (36) is formed in a plate shape and preferably has a substantially circular outer shape. The filter screen has a number of through-openings (38) for the pressurized medium. Such through-openings (38) may optionally be formed to have a circular opening cross-section or to have an arbitrary free-form cross-section. The filtering action of the filter screen (36) can be adjusted to application-specific specifications without adversely affecting the flow coefficient of the pump element (10) through the selection of the material for the filter screen (36), the material thickness, the number of through-holes (38) present, the opening contours of these through-holes (38), the overall cross-section of the openings, and the spacing between the through-holes (38).

[0016] In the illustrated embodiment, the pump piston (14) is formed from two parts: a solid cylindrical first piston portion (40) located outside the pump working chamber (16), and a hollow cylindrical second piston portion (42) that at least partially enters the pump working chamber (16). The second piston portion (42) has a receiving area into which the first piston portion (40) partially protrudes, and the end face of the first piston portion is in contact with the stepped portion of the second piston portion (42) in a coplanar manner. The second piston portion (42) has a plurality of radial holes (44), which open into an axial hole (46) that penetrates the second piston portion (42). The end of the axial hole (46) facing the pump working chamber (16) forms the inlet valve seat (48) of the inlet valve (20) of the pump element (10). The inlet valve seat is controlled by an inlet valve member (50), which in this embodiment of the present invention is formed as a ball and is biased toward the inlet valve seat (48) by an inlet valve spring (52). The inlet valve spring (52) is a coil spring, and the end of this coil spring opposite to the inlet valve member (50) is supported by a valve cage (54). This valve cage (54) protrudes into the pump working chamber (16), and one end of the valve cage is fixed to a second piston member (42). The valve cage (54) has a passage opening (56) on its circumferential surface, and when the inlet valve member (50) is lifted away from the inlet valve seat (48) against the force of the inlet valve spring (52) based on the formed pressure ratio, the pressure medium reaches into the pump working chamber (16) through this passage opening. Furthermore, an annular shoulder (58) is formed at the piston-side end of the valve cage (54), on which one end of the piston return element (18) rests. This shoulder (58) forms an annular seal lip, which seals the guide of the pump piston (14) in the pump working chamber (16) or pump cylinder (12) from the outside.

[0017] The portion of the pump element (10) that protrudes from the pump cylinder (12) is surrounded by a frame-like ring support element (60). The ring support element is attached to the open end of the pump cylinder (12) on its axial extension. The ring support element (60) is preferably made of plastic and has two opposite ends, each formed as a ring (62, 64; Figure 3), which are joined by longitudinal stays (66) to form a single, rigid component. The longitudinal stays (66) are spaced apart from each other along the perimeter of the ring support element (60) and define a flow window (68; Figure 3) between these longitudinal stays, through which the pressure medium can flow into the inlet valve (20) of the pump element (10) with virtually no restriction from the outside. The upper ring (62) of the ring support element (60), located on the side opposite to the pump cylinder (12), guides the first piston portion (40) of the pump piston (14) and has an internal dimension adjusted to match the external dimension of this first piston portion (40). Furthermore, the upper ring (62) supports a molded seal ring (70) positioned outside the ring support element (60). This molded seal ring (70) seals the guide gap between the outer circumferential surface of the pump piston (14) and the inner diameter of the corresponding pump housing of the pump casing.

[0018] The outlet valve closing member (24) is a rotationally symmetric component comprising a central portion (72; Figure 5) and two integrally molded end portions (74, 76; Figure 5) projecting axially outward from the central portion (72) in opposite spatial directions. The outlet valve member (24) cooperates with the outlet valve seal seat (34) of the seat contour (28) at the first end portion (74). This first end portion (74) has an elliptical longitudinal section. From the first end portion (74), a number of projections (78) or teeth project axially outward in the longitudinal axis direction of the outlet valve closing member (24). The outer surface of the outlet valve closing member is located inside a virtual circle having a diameter corresponding to the diameter of the flow passage (26) at the cylinder bottom (12a) of the pump cylinder (12). Based on the protrusions (78), the outlet valve closing member (24) is guided axially within the flow passage (26) of the pump cylinder (12) during opening or closing movements. The pressure medium flows out of the pump working chamber (16) through the spaces between the protrusions (78) and along the circumferential surface of the first end portion (74) of the outlet valve closing member (24).

[0019] The second end portion (76; Figure 5) of the outflow valve closing member (24) is formed, for example, in the shape of a pin, comprising a cylindrical base (80) and a frustoconical base (82) that tapers outward. In this case, the transition portion of the second end portion (76) from the cylindrical base (80) to the central portion (72) forms a right-angled shoulder portion that extends in an annular manner along the outer circumference, and this shoulder portion forms a spring support portion (84) for the outflow valve spring (86) of the outflow valve. Based on the cylindrical base (80), the outflow valve spring (86) and the outflow valve closing member (24) are centered relative to each other.

[0020] On the circumferential surface of the outlet valve closing member (24), at least one recess (88; Figure 5), particularly a notch, groove, or similar, is formed in the transition area from the central portion (72) to the spring support portion (84) of the second end portion (76), extending in the direction of the longitudinal axis of the outlet valve closing member (24). If the outlet valve closing member (24) is assembled in the wrong orientation, this recess (88) will produce a measurably detectable leak when the outlet valve (22) is not being operated, which will allow for easy verification of the incorrect assembly or monitoring of the assembly quality.

[0021] The outlet valve spring (86) is supported at the end opposite to the pump element (10) within a housing (90) of the casing component (92). The casing component (92) has a wall (94) on its end face facing the pump cylinder (12) that protrudes axially in the direction of the longitudinal axis of the pump element (10) and surrounds the housing (90) for the outlet valve spring (86). The wall (94) is surrounded radially outward by a groove-shaped annular passage (96) that opens toward the pump cylinder (12), and this annular passage opens into at least one radial passage (98; Figure 6) of the casing component (92). The protruding wall (94) of the casing component (92) is positioned opposite the hole wall of the second conical hole (32) of the pump cylinder (12) at an axial distance, thereby forming a flow cross section (100) between the two walls. Through this flow cross section, the pressure medium flowing out from the pump working chamber (16) is defined and flows into the annular passage (96), and further proceeds to the radial passage (98) or flows out from the pump element (10).

[0022] Figure 2 shows, A second embodiment of the pump element according to the present invention is shown, which differs from the first embodiment in that at least the inlet valve closing member (50) is formed identically to the outlet valve closing member (24). Accordingly, both valve closing members (24; 50) are formed as rotationally symmetrical components comprising a central portion (72) and two end portions (74; 76) that are integrally formed on the central portion and protrude axially from the central portion (72) in mutually opposite spatial directions. To avoid repetition, reference is made to the related description with respect to Figure 1 for further configuration or shape details of the valve closing members (24; 50).

[0023] Figure 3 shows the ring support element (60) already described in connection with the description of Figure 1, shown in a perspective view as an individual component. As mentioned above, the ring support element (60) is preferably a plastic body formed as rings (62; 64) and having oppositely located end portions. These rings (62; 64) are connected to each other via a plurality of longitudinal stays (66) distributed over the entire circumference, forming an integral rigid component. The ring support element (60) groups 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) into one assembly group. According to the present invention, the ring support element (60) has a plurality of open flow passage windows (68) on its circumferential surface, through which pressure medium can flow into the inlet valve (20) substantially unobstructed, whereby these flow passage windows reduce the pressure loss coefficient of the pump element (10) or enable low pressure loss flow through the pump element. The number and structural detailed design of these longitudinal stays (66) determine the delivery output of the pump element (10).

[0024] Figure 4 shows A filter screen (36) arranged immediately upstream of an outlet valve (22) in a pump element (10) is shown as an individual component. It can be seen that the filter screen (36) is preferably formed as a flat plate having a thickness of a minimum of 0.05 mm and a maximum of 0.50 mm. The filter screen (36) may basically be provided with an arbitrarily shaped outer contour, and the drawing shows an at least substantially circular shape. The filter screen (36) having an outer diameter of 0.5 mm to 12.0 mm is recommended. The filter screen (36) has a predetermined number of through openings (38) for pressure medium. These through openings (38) may also have any contour, but are preferably circular and have a diameter of 0.02 mm to 1.0 mm. A minimum hole spacing of 0.01 mm to 1.00 mm exists between two through openings (38). Combining these geometric conditions with the material strength of the filter screen (36), the viscosity of the pressure medium, the peak volumetric flow of the pump element (10) and the expected size of foreign particles enables an optimal result to be obtained in terms of pressure loss and strength. The filter screen (36) protects the outlet valve (22) from foreign particles, thereby improving reliability or reducing the risk of failure of the pump element (10) or the outlet valve (22).

[0025] Figure 5, The valve closing elements (24;50) of the outflow or inflow valve are shown as separate components. The illustrated valve closing elements (24;50) are substantially rotationally symmetrical bodies comprising a central portion (72) and two end portions (74;76) projecting axially outward on opposite sides of the central portion (72). The central portion (72) has an outer diameter of 1.0 mm to 8.0 mm; the valve closing elements (24;50) as a whole have an axial length of 2.0 mm to 10.0 mm. The outer periphery of the central portion (72) forms a contact surface with the wall of the housing portion (90) in the casing component (92). The central portion (72) is followed by a first end portion (74) having an elliptical, and thus spherical, longitudinal cross-section. When the outflow valve (22) is closed, this first end portion (74) seals the outflow valve seat (34). From the first end portion (74), a minimum of three and a maximum of seven projections (78) protrude axially outward. The outer surface of the valve closing member (24;50) is located inside a hypothetical outer diameter of 1.0 mm to 8.0 mm. The extended length of the projections (78) is a minimum of 0.2 mm and a maximum of 10.0 mm.

[0026] The second end portion (76) of the valve closing member (24;50), located on the side opposite to the first end portion (74), forms a spring support portion (84) for the piston return element (18). This spring support portion (84) is formed by a right-angled annular shoulder portion, which surrounds a pin-shaped core consisting of a cylindrical base (80) and a frustocone (82). Based on the cylindrical base (80), the piston return element (18) and the valve closing member (24;50) are centered relative to each other.

[0027] The second end portion (76) may be formed with any contour, for example, cylindrical, conical, or ball-shaped, but may also be formed by a web. Furthermore, the second end portion may be intentionally formed longer than the block length of the piston return element (18) in the longitudinal direction of the valve closing member (24;50) to protect the piston return element from damage under operating conditions. A local recess (88) is provided at the transition from the spring support portion (84) to the central portion (72), which is configured, for example, as a groove, notch, or similar. This recess (88) has any free shape and will cause leakage if the valve closing member (24;50) is incorrectly assembled and the spring support portion (84) faces the valve seat (34). Thus, incorrectly assembled components can be detected and removed based on leakage measurements during the assembly of the pump element (10).

[0028] The valve closing member (24;50) may, in principle, be manufactured from any material, in which case the smallest possible mass of the valve closing member provides advantages in terms of opening and closing characteristics.

[0029] Figure 6: The valve closing member (24) of the outlet valve (22), which includes a correspondingly positioned outlet valve spring (86), is housed within the housing (90) of the casing component (92) shown in the figure. In this case, a viewer of the drawing is looking at the end face of the casing component (92) facing the pump cylinder (12) and recognizes an annularly continuous wall (94) surrounded by an annular passage (96). The wall (94), together with the second conical hole (32) of the seat contour (28) provided on the pump cylinder (12), forms a predetermined gap or flow cross section (100), through which the pressure medium is defined and reaches the annular passage (96). At least one side of the annular passage (96) has an opening for a radial passage (98). The flow cross section (100), seat contour (28), annular passage (96), and at least one radial passage (98) are structurally coordinated with each other so that the pressure medium flow around the valve closing member (24) generates the defined opening and / or closing motion of the valve closing member. This reduces noise generation from the pump element (10) and extends the service life of the pump element.

[0030] Of course, modifications or advantageous developments in the embodiments described are possible without departing from the scope of protection defined by the following claims.

Claims

1. In particular, a pump element (10) for pumping a hydraulic pressure medium in the brake circuit of an electronically slip-controllable brake system of an automobile, Pump cylinder (12) and A pump piston (14) is slidably guided and housed within the pump cylinder (12) and is driveable to perform periodic stroke motion. The pump working chamber (16) is defined by the pump cylinder (12) and the pump piston (14), An inlet valve (20) controls the pressure medium flowing into the pump working chamber (16), An outlet valve (22) controls the pressure medium flowing out from the pump working chamber (16) and Equipped with, The outlet valve (22) includes an outlet valve seal seat (34) and an outlet valve closing member (24) that cooperates with the outlet valve seal seat (34). In the pump element (10), The outflow valve (22) has a seat contour (28) consisting of two conical holes (30; 32) that are concentric with each other and transition toward each other, and have different conical angles, and the outflow valve seal seat (34) is positioned in the first conical hole (30) which has a sharper conical angle than the second conical hole (32). A pump element (10) characterized by the following features.

2. The pump element according to claim 1, characterized in that the outflow valve closing member (24) has a central portion (72) and two end portions (74; 76) located on opposite sides of the central portion (72) and each projecting outward from the central portion (72).

3. The first end portion (74) positioned in correspondence with the outlet valve seal seat (34) has an elliptical longitudinal cross-section, The second end portion (76) has an annular spring support portion (84) for the outflow valve spring (86). The pump element according to claim 2, characterized in that...

4. The pump element according to claim 2 or 3, wherein at least three projections (78) protrude axially outward from the first end portion (74), and the projections (78) engage with the flow passage (26) of the pump cylinder (12) adjacent to the seat contour (28) for axial guidance of the outflow valve closing member (24).

5. The pump element according to claim 3 or 4, characterized in that the extended length of the second end portion (74) of the outflow valve closing member (24) in the direction of the longitudinal axis is longer than the block length of the outflow valve spring (86).

6. The pump element according to any one of claims 3 to 5, characterized in that at least one recess, particularly a notch or groove, is formed on the circumferential surface of the outflow valve closing member (24) at the transition portion from the central portion (72) to the spring support portion (84), extending in the direction of the longitudinal axis of the outflow valve closing member (24).

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

8. The outlet valve closing member (24) is housed together with the outlet valve spring (86) within the housing portion (90) of the casing component (92). The casing component (92) has a wall (94) on its end face facing the pump cylinder (12) that surrounds the housing (90), the wall being surrounded by an annular passage (96) on its radially outward side, and a radial passage (98) opening into the annular passage. A pump element according to any one of claims 3 to 7, characterized in that

9. The pump element according to claim 8, characterized in that the end face of the wall (94) of the casing component (92) together with the hole wall of the second conical hole (32) forms a flow cross section (100), and the pressure medium flowing out from the outlet valve (22) reaches the annular passage (96) of the casing component (92) through the flow cross section.

10. The pump element (10) has a frame-shaped ring support element (60), and the ends of the ring support element located on opposite sides are formed to form rings (62; 64), and the rings are joined by longitudinal stays (66) to form an integrated component. The longitudinal stays (66) are spaced apart from each other along the circumferential surface of the ring support element (60), and are arranged such that an open passage window (68) through which the pressure medium can flow is created between each of the two longitudinal stays (66). A pump element according to any one of claims 1 to 8, characterized in that

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