JPH05223028A - Manually operable pump for discharge pump of fuel injection pump for internal combustion engine - Google Patents

Abstract

PURPOSE: To enable a valve spring to be assembled without up or bottom engagement and thereby to enable the entire pressure valve to be assembled mechanically in a simple way by using a valve spring which is formed as a linear compression coil spring, as the pressure spring with inwardly attracted end turns at both ends. CONSTITUTION: In a structure in which a closure member 21 of a pressure valve 9 is pressed against the force of a valve spring 23, the valve spring 23 is formed as a linear compression coil spring. The respective end turns 80 of the compression coil spring, receiving the valve closure member 21, are arranged so that spring wire changes over from the outer diameter to a smaller diameter in the plane including an end face 82 of the compression coil spring to define another circle. Thus, the risk that the valve ball is pressed into the valve spring 23 during operation can be avoided by the structure of the valve spring 23 with end turns 80 attracted inwardly at both ends. The valve spring 23 is assembled without up or bottom engagement. In this way, the valve spring 23 is stable and is easy to be handled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manually operable pump for a discharge pump of a fuel injection pump for an internal combustion engine, which comprises a cylinder connected to the casing of the discharge pump, an operating element and a piston rod. A movable piston, the piston forms a pump working chamber together with the cylinder, and the piston has a pin, and the pin controls the outflow from the pump working chamber. The closure member of the type is pressed against the force of the valve spring.

[0002]

PRIOR ART German Federal Patent Application No. 35344
In this type of manually operable pump known from Japanese Patent No. 857, an inward stroke of the piston occurs via the valve tappet against the force of the return spring by the manually operable member.
This valve tappet then impinges a ball valve on the system of the fuel delivery pump, which is connected to said manually operable pump,
At that time, the medium is discharged from the working chamber of the pump into the connected system. During the subsequent automatic return stroke of the piston, the medium is sucked from the suction system of the fuel delivery pump into the working chamber of the pump, the ball valve automatically closing at the end of the return stroke. In this case, pressure valves designed as ball valves are known in various embodiments. (Reliable closing of this pressure valve for the entire life of the injector is an important premise of this valve). The valve closing member is spherical like a known pump,
It may also be shaped like a cone. In that case, the formation of the pressure valve spring has an important meaning. This is because the pressure valve spring plays a very important role in the reliable closing of the valve and must be formed in such a way that a problem-free and simple assembly of the entire pressure valve is possible. The valve springs used in known pumps have a conically tapered end to accommodate a sphere having a diameter smaller than the inner diameter of the valve spring. Optionally, in other words, the sphere cannot be mounted on both sides, which adds to the expense of automatic assembly. In another embodiment of the spring, a so-called diabo with a spring end formed like a hopper by a layer of spring wire abutting each other.
lo) shaped. Even with this configuration, there is a risk that the ball will gradually slide into the valve spring over a long operating time of the pump, which likewise deteriorates the closing accuracy and causes a valve failure.

[0003]

The advantage of the manually operable pump having the construction according to claim 1 is that the ball forming the valve closing member is formed by the construction of the valve spring with the inwardly drawn end wheel at both ends. The indentation of the ball is avoided over a long service life and the ball is reliably guided, which not only avoids the risk of the ball being pushed into the valve spring during operation, but also of both ends of the valve spring. Due to the symmetrical structure, the valve spring can be assembled regardless of the orientation of the top and bottom, so presorting or accurate prepositioning of the spring position is not required.
A simple mechanical assembly of the entire pressure valve is possible. The wire diameter of the pressure valve spring of the present invention can be made larger than that of the known one without changing the strength of the spring due to the large outer diameter of the coil and the long elastic portion, which makes the spring stable. And easy to handle. Further, according to the third aspect of the invention, the valve spring can be incorporated with a predetermined preload by displacing the last end wheel in parallel with the end surface of the valve spring in the direction facing the valve closing member. ,
The wheel receiving the valve closing member is then also located in the plane containing the end wheel. Due to the spherical construction of the valve closing member according to claim 4, mechanical assembly of the pressure valve is advantageous. This is because it is not necessary to consider the embedded position in this case either.

[0004]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a cylinder 1 of a manually operable pump for a discharge pump of a fuel injection pump for an internal combustion engine is connected via a screw-in connecting member 3 in a casing of a fuel injection pump (not shown). Is screwed onto. A piston 5 is arranged in the cylinder 1 so as to be movable in the axial direction, and the piston 5 limits a pump working chamber 7 in the cylinder 1. The cylinder 1 is fitted onto the threaded connecting member 3 and is fixedly connected to the threaded connecting member 3 by means of a crimping point 9 formed as an annular groove. The threaded connecting member 3 is screwed into a casing (not shown) of the fuel injection pump via a male thread 11 provided on the peripheral surface thereof. The screw connection member 3 has a central hole 13
The support sleeve 17 is press-fitted into the central hole, and the central hole is provided with the valve seat 1 through the reduced diameter portion.
5, the valve seat 15 is moved to another reduced diameter portion. A pressure valve 19 is arranged in the central hole 13 and a valve ball 21 serving as a closing member thereof is
A valve spring 23, which is formed as a compression coil spring and is supported by a support sleeve 17, is crimped onto the valve seat 15.
The threaded connecting member 3 forms the second axial limiting portion of the pump working chamber 7 at the end face 24 facing the piston 5.
An O-ring seals the threaded connection member 3 with respect to the cylinder 1, and the O-ring is housed in an annular groove provided on the outer periphery of the portion of the threaded connection member 3 projecting into the cylinder 1. The piston 5 is provided with an end face pintle 27 on the side facing the pump working chamber 7, and a double lip packing 29 cooperating with the cylinder 1 is arranged on the end face pintle 27. The piston 5 has an axial hole 31 and is provided with a hollow cylindrical piston rod 33 on the end face remote from the pump working chamber 7. The hollow chamber 35 of the piston rod 33 forms an annular inner shoulder 37 together with the axial hole 31. The piston 5 transitions to a hollow cylindrical valve tappet 39 on the side facing the pump working chamber 7, which valve tappet 39 comprises a hollow chamber 49. The valve tappet 39 is guided in the axial hole 31 and has an inner shoulder 37 at the end remote from the pump working chamber 7.
Has an outer flange 41 abutting against it, and has a plurality of radial slits 43 and a central pin 45 at the other end. The valve tappet 39 has a stopper 47 formed on the end surface facing the pump working chamber 7.
7 cooperates with the end face 24 of the threaded connecting member 3. The entire manually operable pump working chamber comprises the pump working chamber 7, the hollow chamber 35 of the piston rod 33 and the hollow chamber 49 of the valve tappet 39. The operating element 51, which is made of plastic and is connected to the piston rod 33, is provided with a plate 53 on the side remote from the pump working chamber 7, the outer edge of which is followed by a sleeve 55. The sleeve 55 is provided with an inner groove 57 on its end face side, and the annular raised portion 59 of the stopper ring 61 is engaged in the inner groove 57. An outer ring 63 projects from the outer jacket of the cylinder 1, and a stopper ring 61 is supported on a lower shoulder 65 of the outer ring facing the pump working chamber 7 via a rubber ring 66. A return spring 69 for the piston 5, which is embodied as a compression coil spring, is supported on the upper shoulder opposite to the. The return spring 69 is supported on the opposite side by an annular shoulder 71 of the operating element 51. The piston rod 33 is fixed in the annular groove 73 of the operating element 51. A preloaded retaining spring 75, which is embodied as a compression coil spring, is supported on the second annular shoulder 77 of the actuating element 51 and presses the outer flange 41 of the valve tappet 39 onto the inner shoulder 37 of the piston 5.

The manually operable pump according to the invention operates as follows.

In the rest position shown, the pressure valve 19 is closed and the pump working chamber 7 of the pump and the cavities 35, 49 are filled with air or fuel or a mixture thereof. When pressure acts on the operating element 51 against the return spring 69 as indicated by the arrow in FIG.
The inward stroke of the. In that case, the pin 45 is the pressure valve 1.
The fuel is discharged from the pump working chamber 7 through the pressure valve 19 into the system of the fuel discharge pump adjacent to the threaded connecting member 3 by colliding with the valve ball 21 of No. 9. When the piston rod 33 continues the inward stroke, the stopper 47 cooperates with the end surface 24 of the threaded connecting member 3 to stop the valve tappet 39, and as a result, the pressing force applied to the operating element 51 from the outside is In addition to the force of the return spring 69, the force of the retaining spring 75 must also be overcome.

When the entire inward stroke of the piston 5 is completed,
Air or fuel is discharged from the pump working chamber 7, the hollow chamber 35 and the hollow chamber 49 through the pressure valve 19 to the fuel discharge pump. After the end of the inward stroke, when the force from the outside disappears, the return stroke of the piston 5 is automatically performed in the reverse procedure to reach the valve rest position shown, and the pressure valve is closed. At that time, air or fuel is sucked into the pump working chamber 7 and the hollow chambers 35, 49 from the working chamber of the discharge pump. The alternating suction or discharge of air or fuel from or to the discharge pump fills or empties the injector. During this alternating process, reliable closure of the pressure valve 19 is important. The pressure valve relies on the function of the valve spring, which opens the flow cross section by the opening movement and discharges the valve ball 21 which is abraded by the fuel and presses it against the valve seat again after the discharge.

FIG. 2 is an enlarged view of only the structure of the valve spring 23 according to one embodiment of the present invention and the portion adjacent thereto. The valve spring 23 is located between the support sleeve 17 and the valve ball 21 in the central bore 13 of the threaded connection member 3, as is shown in FIG. The end ring 80 of the valve spring, according to the present invention, spirally draws a three-quarter circle from the circle diameter of the line of the valve spring 23 to a relatively small circle diameter in a plane containing the end face 82 of the valve spring. Are moving. FIG. 3 is a view of only the valve spring 23 of FIG. 2 seen from below. FIG. 4 shows a second embodiment of the valve spring 23 similar to FIG. 2, in which case the end wheel 80
Is additionally offset from the end surface 82 of the valve spring parallel to this towards the center of the valve spring, in addition to the reduction of the helical diameter of the spring wire. Another possible configuration consists in displacing the end wheel 80 outwardly from the end face 82 of the valve spring, which allows the incorporation of the valve spring under preload on the flat end face.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a manually operable pump according to one embodiment of the present invention.

FIG. 2 is a side view of a valve spring according to an embodiment of the present invention.

FIG. 3 is a view of the valve spring shown in FIG. 2 as viewed from below.

FIG. 4 is a view showing a valve spring according to another embodiment of the present invention.

[Explanation of symbols]

1 cylinder, 3 screw connection member, 5 piston, 7 pump working room, 9 caulking point, 11
Male thread, 13 central hole, 15 valve seat, 17 support sleeve, 19 pressure valve, 21 valve ball, 23 valve spring, 24 end face, 25 O ring, 27 end face pintle, 29 double lip packing, 31 axial hole, 33 Piston rod, 35 Hollow chamber, 37
Inner shoulder, 39 valve tappet, 41 outer flange,
43 radial slits, 45 pins, 47 stoppers, 49 hollow chambers, 51 operating elements, 53
Plate, 55 sleeve, 57 inner groove, 59
Annular ridge, 61 stopper ring, 63 outer ring, 65 shoulder, 66 rubber ring, 67 shoulder, 6
9 return spring, 71 annular shoulder, 73 annular groove, 7
5 retaining spring, 77 annular shoulder

Claims (6)

[Claims] 1. A manually operable pump for a discharge pump of a fuel injection pump for an internal combustion engine, the cylinder (1) being connected to the casing of the discharge pump, an operating element (51) and a piston rod. A piston (5) movable by (33) is provided, which piston forms a pump working chamber (7) with the cylinder (1), and the piston (5) forms a pin (45). In the type in which the closing member (21) of the pressure valve (19) for controlling the outflow from the pump working chamber (7) is pressed against the force of the valve spring (23) by this pin, The valve spring (23) is designed as a linear compression coil spring, the last end wheel (80) of this compression coil spring housing the valve closing member (21) being
An internal combustion engine, characterized in that the spring wire rod is formed so as to transition from an outer circular diameter to a relatively small circular diameter in a plane including the end face (82) of the compression coil spring and to draw another circle. A hand-operable pump for the fuel injection pump discharge pump for. 2. The end wheel (80) of each compression valve spring (23) transitions to a relatively small circular diameter and receives the valve closing member (21). )
A hand-operable pump according to claim 1, wherein the plane containing the is offset from the plane containing the end face (82) of the valve spring. 3. Hand according to claim 2, wherein the end wheel (80) of the valve spring (23) is axially outwardly displaced parallel to the plane containing the end face (82) of the valve spring. Operable pump. 4. The hand-operable device according to claim 2, wherein the end wheel (80) of the valve spring (23) is axially inwardly displaced toward the center of the valve spring parallel to the end face (82). Pump. 5. A manually operable pump according to claim 1, wherein the valve closing member (21) of the pressure valve (19) is formed as a sphere. 6. The valve spring (23) comprises a valve closing member (21).
A hand-operable pump according to any one of claims 1 to 5, which is supported on the annular surface formed by the end surface of the sleeve (17) on the side remote from it.