Pump for a vehicle brake system with a valve

Abstract

Piston pump (10) with a valve (34) through which a fluid can selectively flow, which has a receptacle (40) for movably guiding a spherical locking body (38) and a valve seat (44), wherein the valve seat (44) is formed on a housing section (12) of the piston pump (10), which forms a cylinder bore (16) in which a piston (26) is displaceably guided, characterized by that the valve seat (44) is spatially adapted to the spherical shape of the blocking body (38), that downstream immediately behind the valve seat (44), on a component (36) forming the receptacle (40), a free space (84) projecting radially outwards from the spherical blocking body (38) is formed for temporarily receiving fluid passing through the valve seat (44) and that an outflow line (48) is provided downstream of the valve seat (44) and the free space (84) is formed diametrically opposite the outflow line (48).

Description

Background of the invention

[0001] The invention relates to a pump, in particular a piston pump, with a valve through which a fluid can selectively flow, which has a receptacle for movably guiding a spherical blocking body and a valve seat spatially adapted to the spherical shape of the blocking body.

[0002] Piston pumps are used, among other things, in well-known vehicle braking systems, particularly those with anti-lock braking systems (ABS). There, they control the pressure in the wheel brake cylinders. In ABS, for example, they are used to return brake fluid from one or more wheel brake cylinders to a master cylinder. ABS often works in combination with an anti-skid control system (ASR), which also uses piston pumps. Another well-known system, the electronic stability program (ESP), improves driving safety even further compared to ABS and ASR by influencing the vehicle's lateral dynamics. Piston pumps are also used in this system.

[0003] Known pumps used particularly for vehicle braking systems have valves to control the direction of fluid flow through the pump. These valves are generally designed as spring-loaded check valves and serve as inlet and outlet valves. The spring-loaded check valves are preferably designed in the form of ball-seat valves, comprising a blocking body in the form of a ball and a valve seat spatially adapted to the spherical shape of the blocking body. In the ball-seat valves serving as outlet valves, the ball is usually guided in a receptacle formed in an outlet valve cover of the known piston pumps. When fluid flows out through an outflow bore formed in the piston pumps, the ball opens the outlet area according to the following principle: The ball moves tangentially from the sealing seat towards the cover base of the outlet valve cover base and the outflow bore.The ball opens only slightly because a back pressure builds up behind the ball. In addition, the fluid flowing out draws the ball into the discharge groove directly adjacent to the valve seat. Overall, this creates a high back pressure in the pump chamber of conventional piston pumps, resulting in high component stress. Furthermore, due to the reasons outlined above, conventional piston pumps exhibit high drive torque and, consequently, high system performance.

[0004] Pumps according to the features of the preamble of claim 1 are known, for example, from DE 100 22 808 A1.

[0005] DE 199 18 121 A1 further discloses a pump in which a valve seat of a valve is formed on a pin-shaped projection which projects into an open end of a piston. Underlying task

[0006] The invention is based on the object of specifying a pump which can be used in particular for vehicle braking systems, in which only a low component load occurs during operation and which also has a low drive torque and a low system power. Inventive solution

[0007] This object is achieved according to the invention with the pump mentioned at the outset, in which a free space projecting radially outwards from the spherical blocking body is formed downstream immediately behind the valve seat for temporarily receiving fluid passing through the valve seat.

[0008] The free space designed according to the invention creates an outflow cross-section when fluid flows through the valve that is significantly larger than the outflow cross-sections of known pumps. This prevents a throttling effect caused by an insufficient outflow cross-section. This prevents back pressure from building up in the pump according to the invention, resulting in significantly reduced system and component loads.

[0009] In the invention, an outflow line is provided downstream of the valve seat, and the free space is formed essentially diametrically opposite the outflow line. Fluid from the pump according to the invention can flow through the open valve into the outflow line and thus be led out of the pump. Thus, according to the invention, a valve-controlled pump outlet can be created that is not associated with back pressures that would place stress on the component. Advantageous developments of the invention

[0010] In a practical development of the invention, the free space is formed by a concave recess in the component forming the receptacle. The component forming the receptacle can be, for example, an exhaust valve cover.

[0011] Preferably, the clearance is formed by a convex edge design of the component forming the receptacle. A convex edge design of the component forming the receptacle can be achieved with minimal manufacturing effort. Alternatively, the clearance can also be formed by a phase formed on the component forming the receptacle. Just like a convex edge design, a phase can also be realized with minimal manufacturing effort and thus cost-effectively.

[0012] In a further practical development of the invention, the clearance has a depth that is at least 25% of the diameter of the spherical blocking body. By specifying such a clearance depth according to the invention, the throttling effect known from the prior art, with its associated back pressure, can be effectively prevented, while at the same time maintaining known basic functions of the valve, in particular a fluidically optimal outflow upstream of the spherical equator. For this purpose, the clearance should preferably have a maximum height that is at least 25% of the diameter of the spherical blocking body.

[0013] In an alternative practical development of the invention, the valve seat has a valve seat passage with a predetermined mean diameter, wherein the clearance preferably has a depth that is at least 33% of the predetermined mean diameter, in particular to maintain the known, advantageous basic functions of the valve in terms of flow. For this purpose, the clearance should preferably have a maximum height that is at least 33% of the predetermined mean diameter.

[0014] In a particularly practical development of the invention, the pump has a piston which is displaceably guided in a housing section of the pump, wherein the piston has a receiving means for receiving an inlet valve, a sealing element adjoining the receiving means for sealing the piston against the housing section and a piston rod adjoining the sealing element, and wherein the sealing element is formed integrally with the receiving means.

[0015] According to the invention, the sealing element is formed integrally with the receiving means. This has the advantage that, in contrast to pumps known from the prior art, which are used in particular for vehicle braking systems, the functions of the sealing element and the receiving means provided for receiving an inlet valve are performed by just one component. Thus, the invention eliminates one component compared to known solutions, with the result that the assembly and disassembly of the pump according to the invention can be carried out very easily and the tolerance chain is significantly shortened. Furthermore, the manufacturing costs of the pump can be significantly reduced by eliminating one component achieved according to the invention. Finally, the pump according to the invention can be designed to be significantly smaller than known pumps by eliminating one component.

[0016] The inlet valve preferably has a valve seat formed on the piston rod. This design solution according to the invention enables simple assembly and disassembly of the pump. For example, to disassemble the pump, the piston rod adjoining the sealing element must be removed from the sealing element. The inlet valve, which is preferably designed as a seat valve, together with its individual components, comprising, for example, a shut-off body and a spring element, can then be removed without great effort from the receiving means formed integrally with the sealing element. The sealing element, which is received in the cylinder of the pump so as to be longitudinally movable and on which the receiving means is formed integrally, can finally be removed from the cylinder without any problem.

[0017] In a further advantageous development of the invention, a preloading element, preferably in the form of a helical spring, is provided, which bears against the sealing element and with which the piston is urged outwards from the housing section. The preload force transmitted from the preloading element to the sealing element always holds the piston in the outward position. In this way, according to the invention, the outer end face of the piston can be pressed against the eccentric of an eccentric drive in order to convert a translational drive movement provided by the eccentric drive into a reciprocating pumping movement of the piston. By means of the preloading element, the pump according to the invention can be used in conjunction with eccentric drives, which are preferably used in braking systems to drive the pumps.

[0018] In a practical development of the invention, the sealing element is designed in the form of a sealing ring with a sealing ring opening, and the piston rod is received in the sealing ring opening, wherein the piston rod is preferably received in the sealing ring opening with a clearance fit. This clearance fit allows the piston rod to be easily centered in the sealing ring opening. Furthermore, a clearance fit enables the piston rod to be easily released from the sealing ring opening, which is necessary for disassembly purposes. Brief description of the drawings

[0019] In the following, exemplary embodiments of a pump according to the invention are explained in more detail with reference to the attached schematic drawings. It shows: Fig. 1 a longitudinal section of a pump according to the invention, Fig. 2a a longitudinal section of the receptacle and the valve seat of an outlet valve of a piston pump known from the prior art, Fig. 2b a three-dimensional representation of the exhaust valve from Fig. 2a resulting outflow area, Fig. 3a a longitudinal section of the receptacle and the valve seat of an outlet valve of the pump according to the invention, and Fig. 3b a three-dimensional representation of the exhaust valve from Fig. 3a resulting outflow area.

[0020] The Fig. 1 shows a pump according to the invention in the form of a piston pump 10. The piston pump 10 comprises two housing sections 12 and 14, wherein a cylinder bore 16 is formed in the housing section 12, in which a piston 26 is slidably guided. The piston 26 comprises a sealing element in the form of a sealing ring 18, a receiving means 20 for an inlet valve 22 designed as a ball seat valve, which is formed integrally with the sealing ring 18 and in this case is designed as an inlet valve cover, and a piston rod 62 which connects to the sealing ring 18. The piston rod 62 is formed in two pieces and comprises two piston rod elements 28, 30, wherein the piston rod element 28 is firmly received in the piston rod element 30 by means of a press fit in order to create a force-locking connection between the two piston rod elements 28, 30.Due to the intended two-piece design of the piston rod 62, a piston rod 62 can be realized that is cost-effective to produce, since according to the invention a cost-effective rod-shaped piston rod element 28 is connected to a piston rod element 30 that can be provided very cost-effectively in the form of a plastic injection-molded part, turned part, cast part or cold-forged part.

[0021] The receiving means 20 designed as an inlet valve cover and the sealing ring 18 together form a one-piece valve cover / sealing ring combination 24. The piston rod element 30 is received in the sealing ring opening 32 of the sealing ring 18 for connecting the piston rod 62 to the sealing ring 18.

[0022] The piston pump 10 further comprises an outlet valve 34 designed as a ball seat valve, which is arranged within an outlet valve cover 36, wherein a ball 38 of the ball seat valve 34 is guided in a receptacle 40 formed in the outlet valve cover 36. The outlet valve cover 36 can be partially machined or cold-forged. A coil spring 42 supported on the cover base presses the ball 38 against a valve seat 44 formed in the housing section 12 of the piston pump 10, which valve seat 44 adjoins an outlet hole 46 formed in the housing section 12. Brake fluid flowing from the outlet hole 46 through the outlet valve 34 flows via an outflow bore in the form of a radial channel 48 between the outlet valve cover 36 and the housing section 12 toward the pump outlet (not shown).

[0023] Furthermore, a prestressing element in the form of a helical spring 50 is arranged in the cylinder bore 16 formed in the housing section 12. One end of the spring rests against the sealing ring 18 and the other end is supported on the bottom of the housing section 12. The helical spring 50 is prestressed in order to press the two-piece piston rod 62 against the circumference of the eccentric of an eccentric drive (not shown) via the sealing ring 18, against which the piston rod 62 rests with its end face arranged within the piston pump 10. In this way, the outer end face of the piston rod element 28 can always be held in contact with the eccentric. By rotating the eccentric, the entire piston 26 is driven in an axially reciprocating stroke movement, which in a known manner causes brake fluid to be pumped.

[0024] The valve seat 52 of the ball inlet valve 22, which can be produced, for example, by ball stamping, is formed on the end face of the piston rod element 30. This inventive design of the valve seat 52 on the piston rod element 30 of the piston rod 62, in conjunction with the inventive one-piece design of the sealing ring 18 with the receiving means 20 designed as an inlet valve cover in the form of the valve cover / sealing ring combination 24, offers significant advantages during the assembly and disassembly of the piston pump 10. To disassemble the piston pump 10, the piston rod element 30, which is received in the sealing ring opening 32 with a clearance fit, must be pulled out of the sealing ring opening 32. The clearance fit provided according to the invention enables the piston rod element 30 to be easily released from the sealing ring 18.The individual components of the seat valve 22, i.e., the ball 54 and the coil spring 56, can then be easily removed from the receiving means 20. Finally, after pulling the integral valve cover / sealing ring combination 24 out of the cylinder bore 16, the coil spring 50 can be removed from the cylinder bore 16. The assembly of the piston pump 10 is correspondingly simple, with the provided clearance fit enabling easy centering of the piston rod element 30 in the sealing ring opening 32.

[0025] Furthermore, a snap connection in the form of a snap lug 58 is formed on the sealing ring 18, which engages around a shoulder formed on the piston rod element 30. By means of the snap lug 58, the piston rod 62 can be held on the sealing ring 18 during assembly of the piston pump 10, in particular during assembly on the cylinder bore 16, thereby significantly simplifying the assembly of the piston pump 10 according to the invention. The holding function thus realized according to the invention can alternatively also be realized by thermal deformation after the valve cover / sealing ring combination 24 has been placed on the piston rod element 30. According to the invention, the snap lug 58 merely performs the described holding function, which is advantageous for assembly purposes.During operation of the piston pump 10, the spring force of the coil spring 50 ensures that the valve cover / sealing ring combination 24 permanently rests against the piston rod element 30 in the axial direction, despite the clearance fit advantageous for assembly purposes. Furthermore, the snap-in nose 58 acts as a protective seal between the cylinder bore 16 and the piston rod element 30. A sealing lip 60 is also formed on the sealing ring 18 of the valve cover / sealing ring combination 24, which radially seals the cylinder chamber between the piston 26 and the cylinder bore 16 in a pressure-tight manner.

[0026] Finally, the piston pump 10 has a radial bore 96 formed in the piston rod element 30 and a central axial bore 98 through which fluid can flow from outside the piston pump through the inlet valve 22.

[0027] The Fig. 2a shows an outlet valve cover or a receptacle and a valve seat of an outlet valve of a known piston pump, wherein a three-dimensional representation of the resulting outflow area for the outlet valve is shown in Fig. 2b is shown.

[0028] The Fig. 3a shows the outlet valve cover 36 and the valve seat 44 of the outlet valve 34 of the piston pump 10 according to the invention, wherein a three-dimensional representation of the resulting outflow area for the outlet valve 34 is shown in Fig. 3b is shown.

[0029] In the Fig. 2a, Fig. 2b, Fig. 3a and Fig. 3b, the areas which are filled with flowing fluid when flowing through the outlet valve 34 are schematically marked with dots.

[0030] In the exhaust valve cover 36 (cf. Fig. 3a) of the piston pump 10 according to the invention, a circular cylindrical receptacle 40 is formed in which the ball 38 in Fig. 2a to 3b (not shown) of the outlet valve 34. A free space 84 projecting radially outward from the ball 38 is formed in the outlet valve cover 36 of the piston pump 10 according to the invention in order to briefly accommodate the fluid passing through the valve seat 44 and an outflow cross-sectional area 80 as the fluid flows through the outlet valve 34. The free space 84 is formed essentially diametrically opposite an outflow line 48 leading out of the receptacle 40, wherein fluid from the piston pump 10 according to the invention can flow via the open outlet valve 34 into the outflow line 48 and thus out of the piston pump.

[0031] The open space 84 (cf. Fig. 3a) is formed by a concave cavity 82 of the exhaust valve cover 36 and can alternatively be designed as a chamfer, convex radius or groove.

[0032] Compared to the state of the art (cf. Fig. 2a) has the effect of preventing a throttling effect caused by a build-up of fluid downstream behind the valve seat 44. This reduces the back pressure in the pump interior, which results in lower system and component loads and consequently a reduction in the drive torque and system performance. The free space 84 formed in the outlet valve cover 36 has no influence on the basic functions of the ball seat valve; in particular, an outflow is realized in front of the ball equator. A minimal opening of the ball, known from the prior art as a result of the back pressure developing behind the ball, is avoided by the free space 84 according to the invention. In particular, it is avoided that the ball is forced into an outflow groove 86 (cf. Fig. 2a) is drawn, as is the case with the known solution.

[0033] According to the invention, the clearance 84 has a depth 88 that is at least 25% of the diameter of the sphere, and furthermore a height 90 that is at least 25% of the diameter of the spherical blocking body. By dimensioning the clearance 84 in this way according to the invention, the throttling effect known from the prior art with the associated back pressure can be effectively prevented, and at the same time, known basic functions of the exhaust valve 34, in particular a fluidically optimal outflow upstream of the sphere's equator, can be maintained. Alternatively, the advantageous dimensions of the clearance 84 can also be related to the mean diameter 92 of the valve seat passage 94, wherein in the present case, a clearance depth 88 that is at least 33% of the mean diameter and a clearance height 90 that is at least 33% of the predetermined mean diameter represent advantageous dimensions of the clearance 84.

Claims

[1] Piston pump (10) with a valve (34) through which a fluid can selectively flow, which has a receptacle (40) for movably guiding a spherical locking body (38) and a valve seat (44), wherein the valve seat (44) is formed on a housing section (12) of the piston pump (10), which forms a cylinder bore (16) in which a piston (26) is displaceably guided, characterized by , that the valve seat (44) is spatially adapted to the spherical shape of the blocking body (38), that downstream immediately behind the valve seat (44), on a component (36) forming the receptacle (40), a free space (84) projecting radially outwards from the spherical blocking body (38) is formed for temporarily receiving fluid passing through the valve seat (44) and that an outflow line (48) is provided downstream of the valve seat (44) and the free space (84) is formed diametrically opposite the outflow line (48). [2] Piston pump according to claim 1, characterized by that the free space (84) is formed by a concave hollow of the component (36) forming the receptacle (40). [3] Piston pump according to claim 1, characterized by that the free space (84) is formed by a convex edge design of the component (36) forming the receptacle (40). [4] Piston pump according to claim 1, characterized by that the free space (84) is formed by a phase formed on the component (36) forming the receptacle (40). [5] Piston pump according to one of claims 1 to 4, characterized by that the free space (84) has a depth which is at least 25% of the diameter of the spherical locking body (38). [6] Piston pump according to one of claims 1 to 5, characterized bythat the free space (84) has a height which is at least 25% of the diameter of the spherical locking body (38). [7] Piston pump according to one of claims 1 to 6, characterized by that the valve seat (44) has a valve seat passage (86) with a predetermined mean diameter. [8] Piston pump according to claim 7, characterized by that the free space (84) has a depth which is at least 33% of the predetermined mean diameter. [9] Piston pump according to claim 7 or 8, characterized by that the free space (84) has a height which is at least 33% of the predetermined mean diameter. [10] Piston pump according to one of claims 1 to 9, characterized byin that the piston pump (10) has a piston (26) which is displaceably guided in a housing section (12) of the piston pump (10), wherein the piston (26) has a receiving means (20) for receiving an inlet valve (22), a sealing element (18) adjoining the receiving means (20) for sealing the piston (26) against the housing section (12) and a piston rod (62) adjoining the sealing element (18), and wherein the sealing element (18) is formed integrally with the receiving means (20). [11] Piston pump according to claim 10, characterized by that the inlet valve (22) has a valve seat (52) which is formed on the piston rod (62). [12] Piston pump according to claim 10 or 11, characterized by that a prestressing element, preferably in the form of a helical spring (50) is provided, which bears against the sealing element (18) and with which the piston (26) is forced out of the housing section (12). [13] Piston pump according to one of claims 11 to 12, characterized by that the sealing element (18) is designed in the form of a sealing ring with a sealing ring opening (32) and the piston rod (62) is received in the sealing ring opening (32).

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