GB2261919A

GB2261919A - Hand-operated priming pump for a fuel-supply pump of a fuel-injection pump

Info

Publication number: GB2261919A
Application number: GB9224865A
Authority: GB
Inventors: Miklos Mozes
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1991-11-28
Filing date: 1992-11-27
Publication date: 1993-06-02
Anticipated expiration: 2012-11-27
Also published as: DE4139057A1; JPH05223028A; GB2261919B; GB9224865D0

Abstract

A hand-operated priming pump (Fig 1) has a pump working chamber (7, Fig 1) connectable by means of a spring-loaded delivery valve 19 to a working chamber of the fuel-supply pump. The valve spring 23 of the delivery valve is designed as a linear compression spring, whose respective last end turns, 80 receiving the valve closure member 21, are arranged so that the spring wire changes over from the outer diameter of the spring to a smaller diameter over at least part of a circle and preferably 3/4 of a circle. The plane of the end turns may be displaced axially from the plane 82 of the end of the spring (Fig 4). The valve closure member 21 may be a ball. <IMAGE>

Description

1 1 -)-:.1)

DESCRIPTION

HAND-OPERATED PUMP FOR A FUEL-SUPPLY PUMP OF A FUELINJECTION PUMP FOR AN INTERNAL COMBUSTION ENGINE The invention relates to a hand-operated pump for a fuel-supply pump of a fuel-injection pump for an internal combustion engine.

Manually operated priming pumps are known which serve to fill the system when commissioning, or refilling and bleeding after any operation which affects it, such as, for example, changing a filter unit.

In a hand-operated pump known from DE-OS 35344857 the supply stroke of a piston having a valve tappet is initiated by means of a hand-operated member against the force of return springs. at the same time the piston pushes open a ball valve to a system of a fuelsupply pump connected to the pump and in so doing medium is expelled from a working chamber of the pump into the connected system. During the subsequent automatic return stroke of the piston, the medium is drawn from an intake system of the fuel-supply pump into the working chamber of the pump, automatically closing the ball valve at the end of the return stroke. Different design variants are known for the delivery valve which is designed here as a ball and whose reliable closing during the entire serviceable life of the fuel-injection system is an important 1 -2prerequisite for the system to function perfectly. In this way, it is possible, as illustrated in the known pump. for the valve closure member to be both of a spherical and a conical design. In so doing, the design of the delivery valve spring is of great importance, since on the one hand this decisively influences the reliable closing of the valve and also it should be designed in such a way that it is possible to assemble the entire delivery Valve easily and simply using a machine. The valve spring used in the known pump has a conically tapered end for receiving the ball with a smaller diameter than the inner diameter of the spring. This has the disadvantage that it cannot be mounted on both sides, which results in higher automated assembly costs.

With a different design variant of spring, having a so-called diabolo shape the spring ends are funnelshaped by means of spring wire layers lying against each other. However, there is the danger that the ball gradually slides in when the pump is running for a long time, which would likewise result in inaccuracies during the closing process and in the failure of the valve.

In accordance with the present invention, there is provided a handoperated pump for fuel-supply pumps of fuel-injection pumps for internal combustion.

engines having a cylinder connected to a housing of the fuel-supply pump and having a piston which is displaceable by means of an actuating member and a piston rod and the piston forms together with the cylinder a pump working chamber and the piston has pin, by means of which a valve closure member of a a delivery valve controlling an outlet from the pump working chamber is pushed open against the force of a valve spring, wherein the valve spring is a linear compression spring, whose respective end turns which receive the valve closure member are designed in such a way that the spring wire at the spring end face changes over from the outer diameter of the spring into a smaller diameter at least part circle.

This has the advantage that. because the delivery valve spring has inwardly facing end turns at each end, it is possible even during the long running times by reliably guiding the ball, to prevent the ball which forms the valve closure member being pushed in and therefore there is no danger of the valve ball finding its way into the spring (funnel effect). symmetrical design of the spring ends also facilitates that the entire delivery valve can be simply assembled using a machine, since the spring can be installed either way round. Therefore, it is not necessary to pre-sort or to pre-position the spring. The wire diameter of the delivery valve spring of the invention can be greater than that of the known designs, whilst still retaining the stiffness of the spring, because of the greater outer diameter and greater length of the resilient part of the spring. which facilitates the handling of this stable spring.

In addition to this, it is possible by displacing the final end turn parallel to the spring front surface in the direction towards the valve closure member to install a valve spring having a predetermined prestress and the turn receiving the valve closure member then also lies in the plane of the end turn.

Preferably. the end turns are displaced axially inwardly towards the spring's centre, parallel to the spring end surface and the valve closure member is ball-shaped. This has the advantage that it is not necessary to take into consideration the installation position during the automated assembly of the delivery valve.

Specific embodiments of the present invention are described hereinafter, by way of example only, with reference to the accompanying drawings, in which:- Fig.1 is a longitudinal sectional view through the hand-operated pump constructed in accordance with the present invention; Fig.2 is a longitudinal section of a first embodiment of the valve spring having two end turns which change in section to a smaller diameter and which lie in a common plane, the illustration being limited to the inventive part; Fig.3 is a plan view of the valve spring without the ball of Fig.2; and Fig.4 is a second embodiment of the valve spring, where the end turns which change in section to a smaller diameter are displaced out of the plane of the spring end surface parallel to the spring end surface.

With the hand-operated pump i_llustrated in Fig.1 for fuel-supply pumps of fuel-injection pumps for internal combustion engines a cylinder 1 is screwed by way of a screw-down support 3 into a housing of a fuel-supply pump (not illustrated). The cylinder 1 has in its interior a longitudinally displaceable piston 5 which delimits a pump working chamber 7 in the cylinder 1, which is pushed on to the screw-down support 3 and firmly connected thereto by means of caulked points 9 produced by an annular groove. The screw-down support is screwed by way of an outer thread 11 located on its periphery into the housing (not illustrated) of the fuel-supply pump.

The screwdown support has a central bore hole 13. into which is pressed a support sleeve 17 and -6which reduces in diameter to form a valve seat 15. and again reduces in diameter. A delivery valve 19 is arranged in the bore hole 13 and a valve ball 21, functioning as a closure member, of the delivery valve 19 is pushed onto the valve seat 15 by a valve spring 23 as a compression spring which rests on the support sleeve 17. An O-ring 25, which is guided in an annular groove on the periphery of the screw-down support 3 inserted in the cylinder 1, forms the seal between the screw-down support 3 forming with its front surface 24 facing the piston 5 the second axial boundary of the pump working chamber 7 and the cylinder 1.

The piston 5 has on its side facing the pump working chamber 7 an end journal 27 which has a double lip seal 29 which co-operates with the cylinder 1. The piston 5 has an axial bore hole 31 and on the front face remote from the pump working chamber 7 has a hollow cylindrical piston rod 33, whose hollow chamber 35 forms together with the axial bore hole 31 an annular inner shoulder 37. On the side facing the pump working chamber 7, the piston 5 changes to a hollow cylindrical valve tappet 39 having an inner hollow chamber 49, the valve tappet being guided in the axial bore hole 31 and having on its end remote from the pump working chamber 7 an outer band 41 -7resting on the inner shoulder 37 and on the other end a plurality of radial slots 43 and a central pin 45. The front surface of the valve tappet 39 facing the pump working chamber 7 forms a stop 47, which cooperates with the front surface 24 of the screw-down support 3.

The entire working chamber of the hand pump comprises the pump working chamber 7, the hollow chamber 35, the piston rod 33 and the hollow chamber 49 of the valve tappet 39. An actuating member 51 made of a synthetics material is connected to the piston rod 33 and has on its side remote from the pump working chamber 7 a plate 53 with a sleeve 55 extending from its outer edge having an inner groove 57 on its front side which meshes with a bulge 59 of a stop ring 61. An outer ring 63 protrudes from the casing of the cylinder 1 and on its lower shoulder 65 facing the pump working chamber 7 supports the stop ring 61 by way of a rubber ring 66 and on its opposite lying upper shoulder 67 supports a return spring 69 designed as a compression spring for the piston 5. On the opposite side, the return spring 69 pushes against an annular shoulder 71 of the actuating member 51. The piston rod 33 is attached in an annular groove 73 of the actuating member 51. A prestressed retaining spring 75 which is likewise designed as a compression -8spring is supported on a second annular shoulder 77 of the actuating member 51 and holds the outer band 41 of the valve tappet 39 pushed against the inner shoulder 37 of the piston 5.

The hand-operated pump functions as follows. The delivery valve 19 is closed in its normal position and the pump working chamber 7 and the hollow chambers 35 and 49 of the pump are filled with air or fuel or a mixture of the two. A pressure as shown by the arrow in Fig.1 on the actuating member.51 against the force of the return spring 69 produces a supply stroke of the piston 5 and the pin 45 pushes open the valve ball 21 of the delivery valve 19 and at the same time the fuel is pushed out of the pump working chamber 7 by means of the delivery valve 19 into a system of the fuel-supply pump which is contiguous to the screw-down support 3. The continuing supply stroke of the piston rod 33 stops the valve tappet 39 by means of the stop 47 co-operating with the front surface 24 of the screw-down support 3, so that then the pressure force produced from the outside on the actuating member 51, in addition to the force of the return spring 69 and also the force of the retaining spring 75 must be overcome.

With the entire supply stroke of the piston 5, air or fuel is pushed by means of the delivery valve -919 out of the pump working chamber 7, the hollow chamber 35 and the hollow chamber 49 to the fuelsupply pump. After the supply stroke and after the outer pressure force has ceased, the return stroke of the piston 5 occurs automatically in the reverse sequence until it arrives back in the normal position of the pump with a closed delivery valve 19, as illustrated. In so doing. air or fuel is drawn from the working chamber of the fuel-supply pump into the pump working chamber 7 and the hollow chambers 35,49.

By alternating the intake and the compression of the air or fuel from or to the fuel-supply pump, the fuel-injection system is filled and simultaneously bled. With these alternating processes, greater importance is awarded to the reliable closing of the delivery valve 19, which is mainly dependent on the function of the valve spring pressing the valve ball 21 after termination of the supply onto its valve seat 15. the valve ball opening by means of its opening movement a through-flow cross sectional area and being surrounded by fuel.

The enlarged illustration in Fig.2 of the first embodiment is limited to illustrating the design in accordance with the invention of the valve spring 23 and the components contiguous to it. The valve spring 23 is arranged here analogous to that of Fig.1 in the _10bore hole 13 of the screw-down support 3 between the support sleeve 17 and the valve ball 21. The end turns 80 of the valve spring 23 change in section according to the invention in the plane of the spring end surface 82 in the shape of a spiral from the diameter of the windings of the valve spring 23 into a smaller diameter, and in so doing they perform there a three-quarter circle. In order to facilitate a closer examination, Fig.3 is a view seen from below of the valve spring 23 of Fig.2.

Fig.4 is an illustration of a second embodiment of valve spring 23 analogous to Fig.2, where the end turns 80 are also displaced to the spiral-shaped reduction in diameter of the spring wire from the spring front surface 82 parallel to the spring front surface in the direction of the centre of the valve spring. A further design possibility is to displace the end turns 80 outwards from the spring end surface 82, which would facilitate the installation of a prestressed valve spring 23 with a then flat spring end surface.

Claims

-11CLAIMS

1. A hand-operated pump for fuel-supply pumps of fuel-injection pumps for internal combustion engines having a cylinder connected to a housing of the fuelsupply pump and having a piston which is displaceable by means of an actuating member and a piston rod and the piston forms together with the cylinder a pump working chamber, and the piston has a pin by means of which a valve closure member of a delivery valve controlling an outlet from the pump working chamber is pushed open against the force of a valve spring, wherein the valve spring is a linear compression spring, whose respective end turns which receive the valve closure member are designed in such a way that the spring wire at the spring end face changes over from the outer diameter of the spring into a smaller diameter, at least part circle.

2. A hand-operated pump as claimed in claim 1, wherein the smaller diameter portion of the winding extends over three-quarters of a circle.

A hand-operated pump as claimed in claim 1 or 2, wherein each end of the delivery valve spring changes in section into a smaller diameter and the plane of this end winding receiving the valve closure member is displaced out of the spring end face.

4. A hand-operated pump according to claim 3, wherein the end turns of the delivery valve spring are displaced axially outwards, parallel to the spring end face.

5. A hand-operated pump according to claim 3. wherein the end turns of the delivery valve spring are displaced axially inwards in the direction of the spring centre, parallel to the spring end face.

6. A hand-operated pump according to the aforementioned claims, wherein the valve closure member of the delivery valve is a ball.

7. A hand operated pump according to the aforementioned claims, wherein the delivery valve spring is supported on its side remote from the valve closure member on an annular surface formed by means of a front surface of a sleeve.

8. A hand-operated pump substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

z