EP0925446B2 - Radial piston pump for fuel high-pressure supply - Google Patents

Description

The invention relates to a radial piston pump for high-pressure fuel supply in fuel injection systems of internal combustion engines, in particular in a common rail injection system, with a in a pump housing (2) mounted drive shaft which is formed eccentrically or has a plurality of cam-like elevations in the circumferential direction, and preferably with respect to several Drive shaft arranged radially in a respective cylinder chamber pistons which are reciprocally movable in the cylinder chamber when the drive shaft is rotated, and with a suction-side and a high-pressure side check valve and a component with a cylinder space forming through hole in the radially outer end of a closure element is used, wherein the closure element in the longitudinal direction of the cylinder space forming passage opening is closed to the outside pressure-tight.

By Mannesmann Rexroth GmbH, a radial piston pump has become known in which the cylinder space forming member is provided within a housing flange, that is designed as a gehäuseinneres component. The fuel supply to the suction-side check valve takes place from the piston side facing away from the closure element, ie with respect to the drive shaft radially outside of the piston receiving component. Therefore, there must be provided a radially outer suction space, which is surrounded by the housing flange.

From the DE-A 2 338 489 a valve-controlled high-pressure pump is known in which the valve seat of the suction-side check valve is arranged in the housing. Above this check valve is a suction chamber, which is sealed by a closure element to the outside.

From the DE-A 4 324 689 a piston pump of a hydraulic brake system for a motor vehicle is known in which one of two intake valves is arranged in a closure element.

On this basis, the present invention seeks to provide a more compact design of the radial piston pump.

According to the valve body of the suction-side check valve is provided entirely in a cup-shaped recess of the closure element and sealingly biased against the mouth region formed in the bottom of the cup-shaped recess and communicating with the fuel supply opening in the closing direction. The aforementioned opening can in turn, as mentioned above, communicate with an oblique bore in the closure element and an annular space formed between the closure element and the component.

The valve body could be biased in any manner against the bottom of the cup-shaped recess. However, it has proved to be advantageous in terms of design and assembly when a support for a spring biasing the valve body in the closing direction is provided on the open side of the cup-shaped recess facing the pump piston, which spring is then arranged between the support and the piston-facing side of the valve body. To form the support could be provided ansich any radial projections in the cup-shaped recess ansich. However, it has proven to be advantageous in terms of a simple assembly when the support is formed by a kind of cover element with a flow opening for the fuel to be delivered. The lid member could be provided with an internal thread and screwed onto a corresponding flange portion of the closure member or it could be caulked instead of a screw at several points with the flange portion.

The closure element can be an easily mountable closure screw which is screwed into an internal thread provided at the radially outer end of the component.

It has proved to be advantageous if the passage opening in the component is discontinued or stepped and the closure element is pressed sealingly against a step of the passage opening with a, in particular annular collar-like sealing flange and the intake valve is centrally located inside the Sealing flange is arranged. To seal the closure element at the radially outer end, a sealing means, for example in the form of an elastomeric sealing ring can be used, while the seal is effected to the cylinder chamber by pressing the sealing flange against the step. For this it proves to be advantageous if the closure element can be tightened as a screw against the stage.

The fuel supply to the component via a metering unit, not shown.

An oblique bore extending obliquely to the longitudinal direction of the passage opening into the interior of the closure element with respect to the suction-side check valve can be provided by an annular space in order to fluidly connect the suction side of the check valve to the annular space.

The closure element may have on its side facing the piston a cup-shaped recess in which the suction-side check valve is received.

Figur 1

eine Schnittansicht einer nicht erfindungsgemäßen Ausführungsform einer Radialkolbenpumpe, wobei der Schnitt senkrecht zur Antriebswellenachse verläuft;

Figur 2

eine Schnittansicht entlang der Ebene der Pfeile II-II in Figur 1;

Figur 3

eine vergrößerte Detailansicht eines Ausschnitts aus Figur 2;

Figur 4

eine der Figur 3 entsprechende Detailansicht einer nicht erfindungsgemäßen Radialkolbenpumpe mit abweichend gestaltetem Verschlusselement;

Figur 5

eine der Figur 3 entsprechende Detailansicht einer erfindungsgemäßen Radialkolbenpumpe.

Further features, details and advantages of the invention will become apparent from the drawings and the following description of preferred embodiments of the radial piston pump according to the invention. In the drawing shows:

FIG. 1

a sectional view of a non-inventive embodiment of a radial piston pump, wherein the section is perpendicular to the drive shaft axis;

FIG. 2

a sectional view taken along the plane of the arrows II-II in FIG. 1 ;

FIG. 3

an enlarged detail view of a detail from FIG. 2 ;

FIG. 4

one of the FIG. 3 corresponding detail view of a non-inventive radial piston pump with differently designed closure element;

FIG. 5

one of the FIG. 3 corresponding detail view of a radial piston pump according to the invention.

The FIGS. 1 and 2 show a radial piston pump for high-pressure fuel supply in fuel injection systems of internal combustion engines. The radial piston pump is designed with an integrated demand quantity control. As a control concept, the principle of Saugdrosselregelung is pursued. The fuel supply and dimensioning via a metering unit, not shown.

The radial piston pump comprises a drive shaft 4 mounted in a pump housing 2 with an eccentrically formed shaft section 6. On the eccentric shaft section 6 there is provided an intermediate bushing 8 against which the shaft section 6 is rotatable. The intermediate bush 8 comprises three flattened portions 10 which are each offset by 120 °, against which a respective piston 12 with a block-like abutment portion 14 is supported. The pistons 12 are slidably received in the radial direction in each case in a cylindrical space 18 formed by a solid metallic component 16. To form the cylinder space 18, a passage opening 20 is provided in the component 16. The passage opening 20 is stepped and has a smaller diameter portion 22 forming the actual cylinder chamber 18 and a larger diameter portion 24. In the radially outer end of the passage opening 20, ie in the larger diameter portion 24, a closure element 26 is inserted pressure-tight. The closure element 26 is a closure screw 28, which is screwed with the interposition of an O-ring seal 30 in the larger diameter portion 24 of the through hole 20.

On its side facing the pump piston 12, the screw plug 28 has an annular collar-like sealing flange 31, with which the screw plug 23 is sealingly pressed against an axial step portion 32 between the smaller diameter section and the larger diameter section 22, 24 of the passage opening 20.

In the closure screw 28 is a designated generally by the reference numeral 34 intake-side check valve is integrated. The screw plug 28 and the check valve 34, the smaller diameter portion 22 of the through hole 20 and the compressor-side end face 36 of the pump piston 12 define a compressor or high-pressure chamber 38. When the drive shaft 4 of the in FIG. 1 turned position up to 180 °, so while the in FIG. 1 above shown piston moved out of the cylinder chamber 18 under the action of a compression spring 40. During this suction phase, the volume of the pressure chamber 38 increases and the suction-side check valve 34 opens in a manner to be described in more detail. If after further rotation of the drive shaft 4, the piston 12 is moved in the compression direction, the check valve 34 is closed and a in FIG. 2 illustrated high pressure side check valve 42 opens. The high-pressure fuel in the pressure chamber 38 can then flow via an outgoing from the cylinder chamber 18 branch passage 44 via the high-pressure side check valve 42 and a port 46 to an engine piston or a high-pressure reservoir.

As in detail FIG. 3 can be seen, the closure screw 28 in the axial section 32 of the through hole 20 has a slightly recessed in its radial direction outer diameter and limits together with the inside of the larger diameter portion 24 of the passage opening 20 an annular space 48. In this annular space 48 opens a radial Fuel supply opening 50 in the component 16. Then go from the annular space 48 a plurality of obliquely extending to the longitudinal direction of the through hole 20 holes 52, and open in a central cup-shaped recess 54 in the screw 28th

The suction-side check valve 34 is integrated as follows in the cup-shaped recess 54 of the plug 28: In the piston-facing free end of the cup-shaped recess 54 is a valve seat 56 defining element 58 pressure-tight screwed with adhesive. The element 58 has a central passage opening 60 for a plunger 62 of a valve body 64. The valve body 64 has on the piston-facing side of the element 58 on a valve plate 66 which is sealingly against the valve seat 56 can be applied. On the side facing away from the pump piston 12 side of the element 58 within the cup-shaped recess 54, a spring 68 is provided which biases the plunger 62 of the valve body 64 toward the bottom of the cup-shaped recess 54 so that the valve plate 66 sealingly applied against the valve seat 56 is. The spring 68 is supported at one end against the element 58 and at the other end against an abutment 72 formed by a flange bush element 70. The flange bushing element 70 is crimped in the plunger 62 in such a position that a predetermined opening pressure of the check valve 34 is set. The check valve 34 is mounted outside the closure screw 28 with the desired opening pressure and then integrated by screwing the element 58 into the cup-shaped recess 54 in the closure screw 28.

In the FIG. 4 illustrated embodiment differs from the in FIG. 3 represented in that the element 58 'is not screwed by means of adhesive in the cup-shaped recess 54', but is fixed inextricably by a peel riveting, see reference numeral 74th

At the in FIG. 5 illustrated embodiment, the suction-side check valve 80 comprises a valve body 82 which is housed entirely in a cup-shaped recess 84 of the screw plug 86. The valve body 82 is biased by a spring 88 in the direction of the bottom 90 of the cup-shaped recess 84, wherein the spring 88 is supported against the inside of a cover member 92 which is also cup-shaped in cross-section and a flange 94 of the screw plug 86 engages around and this is caulked at several points, see reference numeral 96.

From an annular space 98 provided also in this embodiment, an oblique bore 100 leads to a central blind bore 102 introduced from the bottom 90 of the cup-shaped recess 84. When the valve body 82 is pressed against the bottom 90 of the cup-shaped recess 84 under the tension of the spring 88, Thus, the valve body 82 completely covers the mouth opening of the blind hole 102, and the check valve 80 is closed.

Claims (10)

1. Radial piston pump for high-pressure fuel supply in fuel injection systems of internal combustion engines, in particular in a common-rail injection system, with a drive shaft (4) which is mounted in a pump casing (2) and which is designed eccentrically or has a plurality of cam-like elevations in the circumferential direction, and with preferably a plurality of pistons (12) which are arranged in a respective cylinder space (18) radially in relation to the drive shaft (4) and which are movable back and forth in the cylinder space during the rotation of the drive shaft (4), and with a suction-side and a high-pressure-side non-return valve (80, 42) and with a component (16) having a passage orifice (20) which forms the cylinder space (18) and into the radially outer end of which a closing element (26, 86) is inserted, the closing element (26, 86) being closed in a pressure-tight manner outwardly in the longitudinal direction of the passage orifice (20) forming the cylinder space, and the fuel feed to the suction-side non-return valve (80, 42) taking place via a fuel feed orifice (50) essentially radial in relation to the longitudinal direction and located in the component (16), characterized in that the suction-side non-return valve (80, 42) is integrated into the closing element (26), and in that the valve body (82) of the suction-side non-return valve (80) is provided in a pot-shaped recess (84) of the closing element (86) and is prestressed in the closing direction sealingly against the issue region of an orifice (102) formed in the bottom (90) of the pot-shaped recess (84) and communicating with the fuel feed.
2. Radial piston pump according to Claim 1, characterized in that the closing element (26) is a screw plug (86) which is screwed into an internal thread provided at the radially outer end of the component (16).
3. Radial piston pump according to one of Claims 1 to 2, characterized in that the passage orifice (20) is of offset or stepped design, and in that the closing element (26) is pressed sealingly with a sealing flange (31), particularly resembling an annular collar, against a step (32) of the passage orifice, and the non-return valve (80) is arranged centrally within the sealing flange (31).
4. Radial piston pump according to Claim 3, characterized in that an annular space (98) is provided, radially on the outside with respect to the sealing flange (31), between the closing element (26, 86) and that wall of the component (16) which delimits the passage orifice (20), the fuel feed orifice (50) issuing into the said annular space.
5. Radial piston pump according to Claim 4, characterized in that an oblique bore (100) extending from the annular space (98) obliquely to the longitudinal direction of the passage orifice (20) into the interior of the closing element (26, 86) towards the suction-side non-return valve (80) is provided.
6. Radial piston pump according to one of the preceding claims, characterized in that the closing element (26, 86) has, on its side facing the piston (12), a pot-shaped recess (84) in which the suction-side non-return valve (80) is received.
7. Radial piston pump according to Claim 1, characterized in that a support for a spring (88) prestressing the valve body (82) in the closing direction is provided on the open side of the pot-shaped recess (84), the said open side facing the piston.
8. Radial piston pump according to Claim 7, characterized in that the support is formed by a cover element (92) having a throughflow orifice.
9. Radial piston pump according to Claim 8, characterized in that the cover element (92) has a pot-shaped cross section and engages over a flange portion (94) of the closing element (86).
10. Radial piston pump according to Claim 8 or 9, characterized in that the cover element (92) is caulked together with the closing element (86) at a plurality of points.

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