DE2628591A1 - FUEL INJECTION PUMP FOR INJECTION COMBUSTION MACHINES - Google Patents

Description

DipL-ing. Linen weaver

Dipl.-Ing. Ζϊ - ".. 33ΠΠαΠΠ D:,: i.; Nj. V. v / Sf! 50rsky

8 ^ ar.ohen2, Rosental V Tel. 260 3989

June 25, 1976

Friedmann & Maier Aktiengesellschaft

in Hallein (Austria)

Fuel injection pump for injection internal combustion engines

609882/0402

The invention relates to a fuel injection pump for injection internal combustion engines with at least a pump element inserted into a bore in the pump housing, which has a pump piston liner and a pressure piece which, with the interposition of a pressure valve seat having pressure valve body is pressed against the pump piston liner, with pump piston liner, pressure valve body and pressure piece have essentially the same outer diameter and in a common bore of the injection pump housing are used. Seals inserted between the sealing surfaces do not hold up to high injection pressures and in these cases the end faces of the pump piston liner, Pressure valve housing and pressure piece in contact with one another directly and without interposed seals brought, these end faces are finely ground, polished or lapped so that the end faces pressed against one another even the poetry result. In such a training it is known to interconnect the sealing surfaces by one in one of the in contacting surfaces arranged groove into an inner and an outer ring surface to subdivide the specific To increase surface pressure. The outer ring surface is here for the precise position fixing of the pressure valve body in the Bore in the pressure pump housing is required and there should be the risk of tilting or slanting through this outer annular surface of the pressure valve body can be avoided during installation. Even with such a training, however, are still evident high pressures, which today already have peak values of 1200 bar achieve leakage oil losses, whereby the leakage oil passing through forms so-called firing channels, which develop in the course of the Enlarge the company. An excessive increase in the contact pressure is not possible for reasons of strength.

The invention now relates to such a fuel injection pump, in which the pump piston liner, Pressure valve body and pressure piece are in direct contact with the pressure valve body while avoiding a seal and

609882/0402

the contact surfaces between the pressure valve body and the pump piston liner and between pressure valve body and pressure piece are limited to an inner and an outer ring surface, and consists essentially in that the outer surface of at least one of the pressed against each other, of pressure piece, Pressure valve body and pump piston liner formed parts, in particular the lateral surface of the pressure valve body at least has an annular groove which extends radially inward at least to a radius which is the inner radius of the outer Corresponds to the ring surface. In this way, a suspension is achieved in the area of the outer ring surfaces, which the pressing force in the Reduced area of these outer ring surfaces. As a result, the pressing pressure acting on the unit area of the inner ring surface becomes increases and thereby improves the sealing effect, without the clamping elements causing the compression of the sealing surfaces, like screws or the like., are subject to higher loads. This annular groove expediently extends up to a radius which is at most corresponds to the outer radius of the inner ring surface. The pressing pressure is thus transferred directly to the inner ring surface, while the outer ring surface is largely relieved.

By means of the annular groove or grooves, annular beads are isolated on the outer surface of the component in question, which wear the outer ring surfaces used for sealing. The strength of these annular beads measured in the axial direction determines the Suspension and thus the contact pressure. The stronger these annular beads are, the greater the contact pressure. When the ring groove in the If the lateral surface of the pressure valve body is provided, the mean width of this annular groove determines the strength of the one that delimits it Annular beads. According to the invention, the mean width of the annular groove measured in the axial direction expediently corresponds to one Quarter to a third, preferably approximately half of the axial extent of the pressure valve body. With such a Sufficient resilience of the pressure valve body is achieved in the area of the outer ring surfaces.

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.6 09882/0402

The invention is illustrated schematically in the drawing using an exemplary embodiment. · _:

1 shows a cross section through the injection pump in the area of a pump element. Fig. 2 shows a cross section through the upper parts on a larger scale of a pump element. ■. · '. -

- Fig. I shows a cross-section through the axis of a Furapenelementes a single-digit ^ injection pump "with external drive, soft under the mediation of a flange 100 flanged to the motor housing of the internal combustion engine and is driven by a cam 101 of a shaft mounted in the motor housing ', the roller tappet 102. ". leading approach 103 hindurehragt through an opening in the motor housing. The invention can, however, in the same Way can also be found in a conventional single-digit or multi-digit injection pump with its own camshaft.

A pump piston sleeve 3, a pressure piece 4 and a pressure valve body 5 are accommodated in a bore i of the injection pump housing 2. The pressure valve seat 6, against which the pressure valve cone 7 is pressed by the pressure valve spring 8, is provided in the pressure valve body 5. 9 is a filler piece which serves to center the pressure valve spring 8. 10 is the connection for the fuel line. A chipboard 11 presses the pressure piece h _r _ pressure valve body 5 and the pump piston sleeve 3 against one another. No seals are provided between the pressure valve body 5 and the pump piston liner 3 on the one hand and between the pressure valve body 5 and the pressure piece k on the other hand, but the bare ground or polished or lapped surfaces of these parts lie against one another.

The surfaces of the pressure valve body each have a groove 12 and those in contact with the pressure valve body standing surface of the pressure piece is at 13 ring-

_ 2t _ 6-09882 / 0402

shaped excepted. In this way, there are inner ring surfaces 14 and outer annular surfaces 15 formed on which the contact of the pressure valve body 5 with the pump piston sleeve 3 and the contact of the pressure valve body 5 with the pressure piece 4 is limited. By limiting to this Ring surfaces are thus made smaller the contact surfaces and there is the surface pressure on these contact surfaces enlarged. The two annular grooves -12 are connected by a bore and this bore is connected to a transverse bore 17 the annular gap 18 between pressure valve body S and housing bore 1 in connection. In this way can about the two inner ring surfaces 14 escaping leakage oil back to the suction chamber 19 get to the injection pump. Such a construction shown in Fig. 1 is known.

When not clamped together, there is a slight play on the annular sealing surfaces 14 and 15 on both the lower and upper surfaces of the pressure valve body, i.e. both between pressure valve body 5 and pressure piece 4, as well as between pressure valve body and pump piston liner 3. Bsi an embodiment according to the invention is now this entire game ^ .both see each other in contact with outer annular surfaces 15 slightly greater than the total play between those in contact with each other standing inner ring surfaces 14. This will be the outer ring surfaces 15 relieved and the entire on the inner annular surfaces 14 acting pressing force is increased.

Fig. 2 shows another embodiment of the invention on a larger scale. 'This embodiment differs differs from the embodiment according to FIG. 1 only in that on the lateral surface of the pressure valve body 5 an annular groove 20 is provided. This annular groove extends radially inward over the inner radius R of the annular surfaces in addition almost to the outer radius r of the inner ring surface 14. The mean width a of this measured in the axial direction Annular groove 20 corresponds approximately to half of the axial extension b of the pressure valve body 5. In this way

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~~. In the area of the outer ring surface 15, two flanges 21 are formed, which can spring slightly against one another, so that the specific surface pressure in the area of the outer ring surface 15 is reduced. The specific surface pressure exerted on the inner annular surfaces 14 therefore increases, since the full material cross-section of the pressure valve body 5 is maintained in this area. The sealing effect of the inner ring surfaces is therefore improved.

In the exemplary embodiment of the drawing, the annular groove 2O is provided in the pressure valve body 5. But it can instead of this annular groove 20 or in addition to it, a corresponding annular groove in the annular surfaces 15 adjacent to it Areas of the jacket of the pressure piece 4 urio. the pump piston liner 3 may be provided.

In all cases, the specific surface pressure in the area becomes the same with the overall pressure of the outer ring surfaces 15 and, instead, the specific surface pressure in the area of the inner ring surfaces 14 enlarged so that the sealing effect is improved without increasing the stress on the material.

Claimsι

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6,9882 / (Η0?

Claims (3)

Claims 1 J Fuel injection pump for fuel injection engines with at least one pump element inserted into a bore in the pump housing, which is a pump piston liner and has a pressure piece which, with the interposition of a pressure valve body having the pressure valve seat is pressed against the pump piston liner, with pump piston liner and pressure piece are in direct contact with the pressure valve body and the contact surfaces between Pressure valve body and pump piston sleeve and between pressure valve body and pressure piece on an inner and an outer one Annular area are limited and the pump piston liner, pressure valve body and pressure piece have essentially the same outer diameter have and are inserted into a common bore of the injection pump housing, characterized in that that the outer surface of at least one of the pressure piece (4), pressure valve body (5) and pump piston liner pressed against one another (3) formed parts, in particular the lateral surface of the pressure valve body (5) at least one annular groove (20) which extends radially inwardly at least up to a radius which is the inner radius (R) of the outer annular surface (15) corresponds. 2. Fuel injection pump according to claim 1, characterized in that the annular groove (20) extends up to extends a radius which corresponds at most to the outer radius (r) of the inner annular surface (14). 3. Fuel injection pump according to claim 1 or 2, characterized in that the measured in the axial direction mean width (a) of the annular groove (20) a quarter to a third, preferably approximately half of the axial extent (b) corresponds to the pressure valve body (5). 609882/0402