Piston pump

Abstract

A piston pump (10) for supplying pressure fluid into at least one vehicle brake, into a master cylinder, into a pressure fluid reservoir, or into a pressure fluid accumulator of a controlled vehicle brake system, is integrated into an accommodating member (3) in a simple and space-saving manner. A plurality of valve seats (38, 54) of non-return valves (32, 33, 36, 37) are kept as free as possible from pressing or attaching forces in that a sleeve (18, 19) has a radial flange for being secured in position between a closing member (52) and the accommodating member (3).

Description

BACKGROUND OF THE INVENTION

The present invention relates to a piston pump for supplying pressure fluid into at least one vehicle brake, into a master cylinder, into a pressure fluid reservoir or into a pressure fluid accumulator of a controlled vehicle brake system.

A piston pump of this type is e.g. disclosed in DE 100 22 811 A1 and comprises, among others, a sleeve retained in a stepped bore. This sleeve is pressed into the stepped bore by a closing member that abuts axially on a bottom of the sleeve. It is disadvantageous in this type of construction that the pressing and attaching forces introduced into the sleeve may cause a deformation of a seat for a non-return valve. This jeopardizes the operational safety of the vehicle brake system.

A generic piston pump is described in DE 197 53 083 A1. A closing member bears in an axial direction directly against the sleeve, pressing it axially against a bore step. The forces introduced through the sleeve and a conical abutment surface of the sleeve in the area of the non-return valve can cause a deformation of the sleeve in the area of the valve seat.

In view of the above, an object of the invention is to disclose a means permitting an integration of a piston-pump subassembly into an accommodating member, while in particular valve seats of non-return valves can be retained so as to be free from pressing or attaching forces being due to the assembly and from resultant deformations.

SUMMARY OF THE INVENTION

According to the invention, this object is achieved in that the sleeve includes a radial flange, and in that the radial flange is compressed between the closing member and the accommodating member for securing the sleeve in position in an axial direction. This measure is used to retain the pump subassembly in the accommodating member, while the necessary attaching forces are introduced into the sleeve at a point spaced from the seat of non-return valves, thereby preventing that the sealing effect of the non-return valves is impaired.

In a favorable embodiment of the invention, the stepped bore has a bore step with a bore diameter that is designed larger than the radial flange so that an exclusively axial abutment of the radial flange prevails. This prevents an application of force at the periphery of the sleeve which causes out-of-true operation or deformations of the sleeve.

It is furthermore favorable that the sleeve includes a bowl-shaped portion which is used as a support for the resetting spring and has a cylindrical wall and a bottom on which one end of the resetting spring is abutting. This obviates the need for a separate assembly of a separate spring retainer in the accommodating member.

A portion of the sleeve can be substantially V-shaped or U-shaped in cross-section so that an indentation provided between the wall and a collar is used to accommodate the resetting spring, and an outside indentation formed by the collar accommodates a non-return valve in such a fashion that resetting spring, sleeve and non-return valve intersect at least in the area of the portion in a radial direction. An arrangement of the components involved that achieves especially short dimensions is thereby given, and a seat for a non-return valve can be provided in the bottom area of the sleeve. The seat is preferably provided at the collar.

Centering of the spring is enabled when the collar in the seat area has a substantially conical portion, the diameter of said portion corresponding basically to the diameter of the resetting spring and the portion engaging the resetting spring. The conicalness facilitates the placement in the event of an inexact feeding of components.

The mounting space requirement is furthermore reduced when the closing member has a bowl-shaped design and includes a wall and a bottom, and the bowl-shaped portion of the sleeve is accommodated in an inner space of the closing member, and an end surface of the wall maintains the radial flange in abutment on the bore step.

Essential parts of the piston pump, in particular the sleeve and the portion, due to the protuberances are formed as sheet-metal shaped parts being fastened in the area of the radial flange to the closing member by means of calked or pressed engagement.

In principle, the pump of the invention shows a good aspiration behavior, even at low temperatures of the pressure fluid, because the construction allows correspondingly expanded aspiration cross-sections especially as regards the channel routing and the piston configuration.

Further details of the invention can be taken from the following description making reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 shows a cross-sectional, enlarged view of a first and second embodiment of a piston pump separated by an axle center;

FIG. 2 shows an enlarged view of a variant according to FIG. 1;

FIG. 3 shows a third embodiment of a piston pump;

FIGS. 4 a-c show details of different sleeves, which are principally based on the embodiment shown in FIG. 3.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an assembly 1 with a schematically illustrated drive 2, in particular an electric motor, which is flanged to an accommodating member 3 for electromagnetically operable valves, channels, accumulator or damper chambers and to a piston pump 10. An electronic control unit 4 (shown only schematically) is provided on an opposite side of the accommodating member 3. The illustrated assembly 1 is in particular used for slip control or driving stability control in motor vehicles, yet similar or different cases of application are also feasible.

A preferably central stepped bore 5 of the accommodating member 3 accommodates a sealed roller bearing 6 of the drive shaft 7 whose free end is designed as an eccentric 8 projecting into a crank chamber 9 of the stepped bore 5. It is principally possible that the eccentric 8 is ground out directly at the drive shaft 7 or motor shaft, or is designed as a separate component and attached to the drive shaft. For an extended pump operation life the crank chamber 9 can be flooded with leakage fluid, especially with brake fluid, and a reservoir connected to the crank chamber 9 is used for the fluid take-up within the drive 2, the accommodating member 3 or the electronic control unit 4.

The eccentric 8 is equipped with a needle bearing 11 which is closed on one side by a bowl-shaped outside ring 12, the bowl bottom 13 thereof, with a wart-like projection, being movable into abutment on an end surface of the drive shaft in a punctual manner and with low friction. A bottom 14 of the crank chamber 9 has a ball 15 so that the bowl bottom 13 abuts with an outside surface remote from the motor shaft on the ball 15 in a low-friction fashion, and the outside ring 12 that can be rotated relative to the accommodating member 3 does not have any direct contact to the material of the accommodating member 3. This counteracts frictional stress of the accommodating member 3, without having to apply wear-resistant material coatings such as eloxal coatings onto walls of an accommodating member 3 made of aluminum.

As shown in FIG. 1, two pistons 16, 17 of the piston pump 10 which are in each case of bipartite design are arranged and guided within a stepped bore 64, 65, movable in a sleeve 18, 19. The pistons extend with a first hydraulic diameter a supply chamber 30, 31 and reach with an end 20, 21 into the crank chamber 9 where they contact a periphery of the outside ring 12. Another end 22, 23 of the pistons 16, 17 has another, second hydraulically active diameter and projects into a displacement chamber 24, 25. While the second end 22, 23 of the pistons 16, 17 is sealedly guided by way of a sealing and guiding ring 26, 27 in the sleeve 18, 19, another guiding and sealing assembly 28, 29 allows arranging the supply chamber 30, 31 between the mentioned sealing assembly 28, 29 and a non-return valve 32, 33 acting as a suction valve. From a pressure fluid inlet E the pressure fluid propagates via a channel and a filter 34, 35 arranged at a sleeve into the supply chamber 30, 31. During the aspiration stroke, pressure fluid is conveyed into the displacement chamber 24, 25, with the non-return valve (suction valve) 32, 33 open, and during the displacement stroke it is conveyed into a pressure fluid outlet A, with the non-return valve (pressure valve) 36, 37 open. It must be added that the effective hydraulic piston diameter in the displacement chamber 24, 25 along with the hydraulically effective diameter in the supply chamber 30, 31 permits improved aspiration properties in the event of viscous pressure fluid. Further details of the piston pump will be explained by way of FIG. 2 showing the left-hand part of FIG. 1 on an enlarged scale.

As can be seen, the stepped end of the piston 16 which is also split like a fork by at least one groove has a plate-shaped valve seat 38 whose cylindrical wall portion 39 is slipped at least partly onto the end 22. It also carries the guiding and sealing ring 26 on an outside surface. The valve seat 38 includes a stop 40 to secure the sealing ring 26 axially in position. A component 42 which acts additionally as a spring plate for a piston resetting spring 41 and a valve spring 45 or, like in FIG. 2, a separate spring plate abuts in the shoulder area of axially bent legs 43 on a front side of the valve seat 38. Radial legs 44 can abut flatly on the sealing ring 26 in an axial direction so that the sealing ring is fixed in position on the piston 16 and oscillates with it in relation to the accommodating member 3. As is further shown in FIG. 2, the legs 43 of the component 42, which point in the axial direction, can engage into a slot between the cylindrical wall portion 39 of the valve seat 38 and the sealing ring 26, whereby the radial counter pressure of the sealing ring 26 on the sleeve 18 can be increased. A cylindrical component portion 46 prevents the valve spring 45 from bulging.

The piston resetting spring 41 extends through the entire displacement chamber 24 and bears with one end on an abutment 47 that is remote from the piston and also serves as a bottom for the sleeve. According to the embodiment of FIG. 1, the sleeve 18 is shaped like a bowl, and the support 47 is configured as a component bulged like a plate and having a radial flange 48, a wall 49 and a bottom area 50. As becomes apparent, the radial flange 48 abuts flatly on a radial flange 51 of the sleeve 18. While the wall 49 is bulged cylindrically in the direction of the closing member 52, the bottom area 50 includes a collar 53 which points oppositely, that means in the direction of piston 16, and has a seat 54 for a valve member 55 of the non-return valve (pressure valve) 36. Consequently, a bulge provided between collar 53 and wall 49 on the side of the displacement chamber is used to accommodate the resetting spring 41, and a bulge formed by the collar 53 itself is used to accommodate essential parts of the non-return valve 36 such as valve member 55 and valve spring 56 in particular. The mentioned components are hence arranged in each other in such a fashion that they intersect at least in part in a radial direction, what results in mounting space economy. As becomes further apparent from FIGS. 1 and 2, the collar 53 has a largely conical form. Its (outside) diameter initially corresponds substantially to the (inside) diameter of the resetting spring 41, subsequently tapering in the direction of seat 54. This arrangement improves the centering of the resetting spring, in particular during the assembly.

Various measures are possible to support the valve spring 56 of the non-return valve 36. As can be seen in FIG. 1 by way of the embodiment in the right-hand half of the drawing, the valve spring 56′ can be supported axially directly on the closing member 52′, and a substantially plate-shaped retaining component 57′, the shape of which comes close to the shape of the support, is provided with a guiding portion 58′ for the valve spring 56′. A radial flange 59′ of the retaining component 57′ comprises edge portions 60 being bent in such a fashion that they embrace the radial flange 51, 48 of sleeve 19 and support 47′ in order to fix an independently operable modular unit composed of sleeve 19, resetting spring 41, non-return valves 33, 37 and the retaining component 57′. According to a modified embodiment, as can be taken from FIG. 1 in the left-hand half of the drawing (as well as from FIG. 2 on an enlarged scale), it is possible that the retaining component 57, in addition to the guiding portion 58, includes a stop 61 for the valve spring 56. Finally, in a simplified variant according to FIG. 3, the retaining component 57 may be omitted because the valve spring 56″ abuts axially on the closing member 52″ and the latter includes either a dome-shaped elevation 62, 63 or an elevation 64, 65 shaped like a socket, as is shown in dotted lines in FIG. 2. In the event of rationalization of the separate retaining component 57, the independently operable unit is manufactured in that the closing member 52″ is calked with the radial flange 48, 51, as can be seen in FIG. 3.

In all embodiments the sleeve is retained by a closing member 52, 52′, 52″ in the stepped bore of the accommodating member 3. For this purpose, the closing member 52, 52′, 52″ is calked or clinched with the accommodating member 3, as is shown in the Figures. A clinched engagement implies in this context that the closing member 52, 52′, 52″ is made of a material harder than the accommodating member 3, and that the closing member 52, 52′, 52″ in the area of a bore wall is further provided with a contour producing a form lock by means of cold working between the components involved in the event of a relative displacement between closing member 52, 52′, 52″ and accommodating member 3.

In order to integrate the closing member 52 into the independently operable pump assembly even in the type of construction according to FIG. 1, it is possible that it has a substantially concave design for accommodating parts of the pump cartridge (comprising sleeve 18, 19, non-return valves 32, 33, 36, 37), resetting spring 41, piston 16, 17) and includes a wall 66 with an end surface 67 and a bottom 68, while the inside contour has a profiling or fit receiving the retaining component 57 in a clamping manner. This achieves a space-saving, yet easy-to-assemble arrangement. However, provisions must be made to ensure that there is a sufficient flow cross-section for the pressure fluid.

FIGS. 3 a to 3c show design variants of a sleeve 18, which is preferably manufactured by deformation and which includes a radial flange 51. In general, the basic idea of the invention renders it possible to shape essential parts of the pump cartridge, in particular its sleeve 18, 19, including bottom (support 47) as sheet-metal shaped parts or punched parts, without having to fear functional impairment in the area of the non-return valves 36, 37 due to deformations caused by the assembly. This is because starting from the closing member 52, retaining and pressing forces are mainly introduced only into a radial flange 51 of the sleeve 18, 19, from which these forces are then conveyed into a bore step 69 of the accommodating member 3. Based thereon it is possible to impart a one-part design to the sleeve 18c by means of deformation according to FIG. 4c, or to make it up of several parts, as is illustrated in FIGS. 4a, b. In this arrangement, the component forming the bottom or support is molecularly interfaced with the tubular guiding portion of the sleeve 18a,b, and the radial flange can be provided at the bottom according to FIG. 4a, or at the guiding portion according to FIG. 4b, without departing from the spirit of the invention. In all three cases, however, there is calking engagement between closing member 52a,b,c and radial flange 51a,b,c, as has been described already with regard to FIG. 2.

LIST OF REFERENCE NUMERALS

• • 1 assembly
  • 2 drive
  • 3 accommodating member
  • 4 control unit
  • 5 stepped bore
  • 6 roller bearing
  • 7 drive shaft
  • 8 eccentric
  • 9 crank chamber
  • 10 piston pump
  • 11 needle bearing
  • 12 outside ring
  • 13 bowl bottom
  • 14 bottom
  • 15 ball
  • 16 piston
  • 17 piston
  • 18 sleeve
  • 19 sleeve
  • 20 end
  • 21 end
  • 22 end
  • 23 end
  • 24 displacement chamber
  • 25 displacement chamber
  • 26 guiding ring
  • 27 guiding ring
  • 28 sealing assembly
  • 29 sealing assembly
  • 30 supply chamber
  • 31 supply chamber
  • 32 non-return valve
  • 33 non-return valve
  • 34 filter
  • 35 filter
  • 36 non-return valve
  • 37 non-return valve
  • 38 valve seat
  • 39 wall portion
  • 40 stop
  • 41 resetting spring
  • 42 component
  • 43 leg
  • 44 leg
  • 45 valve spring
  • 46 component portion
  • 47 support
  • 48 radial flange
  • 49 wall
  • 50 bottom area
  • 51 radial flange
  • 52 closing member
  • 53 collar
  • 54 seat
  • 55 valve member
  • 56 valve spring
  • 57 retaining component
  • 58 guiding portion
  • 59 radial flange
  • 60 retaining portion
  • 61 stop
  • 62 elevation
  • 63 elevation
  • 64 stepped bore
  • 65 stepped bore
  • 66 wall
  • 67 end surface
  • 68 bottom
  • 69 bore step
  • E inlet
  • A outlet
  • Ax axial direction
  • R radial direction

Claims

1-9. (canceled)

10. A piston pump (10) for supplying pressure fluid for a controlled vehicle brake system, including the following features: a piston (16, 17) is movably arranged in a stepped bore (64) of an accommodating member (3) provided with a closing member (52); the piston (16, 17) is guided in a sleeve (18, 19) at least in sections; the sleeve (18, 19) comprises a non-return valve (32, 33, 36, 37) which is arranged coaxially to the piston (16, 17) and is used for the ventilation of a working chamber (24, 25) into which the piston (16, 17) plunges; a resetting spring (41) is provided within the sleeve (18, 19) between a support (47) and the piston (16, 17), wherein the sleeve (18, 19) includes a radial flange (51), and wherein the radial flange (51) is compressed between the closing member (52) and the accommodating member (3) for securing the sleeve (18, 19) axially in position.

11. The piston pump as claimed in claim 10, wherein the stepped bore (64) has a bore step (69) with a bore diameter designed to be larger than the radial flange (51) for an exclusively axial abutment of the radial flange (51).

12. The piston pump as claimed in claim 10, wherein the sleeve (18, 19) includes a bowl-shaped portion which is used as a support (47) for the resetting spring (41) and has a wall (49) and a bottom area (50) on which one end of the resetting spring (41) is abutting.

13. The piston pump as claimed in claim 12, wherein the portion of the sleeve (18, 19) is bulged to be substantially V-shaped or U-shaped in cross-section so that an indentation provided between the wall (49) and a collar (53) is used to accommodate the resetting spring, and wherein an outside indentation formed by the collar (53) accommodates a non-return valve (36, 37) in such a fashion that resetting spring (41), sleeve (18, 19) and non-return valve (36, 37) intersect each other at least in the area of the portion in a radial direction R.

14. The piston pump as claimed in claim 12, wherein the collar (53) in the seat area has a substantially conical portion, the diameter thereof corresponding basically to the diameter of the resetting spring (41), and wherein the portion engages the resetting spring (41).

15. The piston pump as claimed in claim 12, wherein the closing member (52) has a bowl-shaped design and includes a wall (66) with an end surface (67) and a bottom (68), and wherein the sleeve (18, 19) at least with the support (47) is accommodated in an inner space of the closing member (52), and wherein the end surface (67) retains the radial flange (51) in abutment on the bore step (69).

16. The piston pump as claimed in claim 10, wherein a seat (54) for a non-return valve (36, 37) is provided in a bottom area of the sleeve (18, 19).

17. The piston pump as claimed in claim 16, wherein the seat (54) is provided at the collar (53).

18. The piston pump as claimed in claim 16, wherein the sleeve (18, 19) and in particular the support (47) are designed as sheet-metal shaped parts, and wherein these are fastened in the area of the radial flange (51) to the closing member (52) by means of calked or pressed engagement.