JPS5855349B2 - injection pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has the following characteristics for internal combustion engines: a)
a flanged bushing installed in a receiving hole formed in the housing of the pump to guide the piston; b) a suction hole and a discharge hole are coaxially opposed and coaxially formed in the bushing; d) the piston has a first control edge and a second control line in opposition at its upper end, and a lower control edge below the second control edge, d) cooperating with the first control edge of the piston; said suction hole is opened in a straight line through the bush; and e) said discharge hole is provided to cooperate with the second control edge and the lower control edge of the piston. This applies to a multi-cylinder injection pump that satisfies the following.

In such known injection pumps, a fine uncontrolled jet flows out of the pump chamber at high pressure through its lower control edge at the beginning of the opening of its discharge hole, for example in a pump made of a common aluminum alloy. Particularly noticeable in the case of the housing, there is a problem in that the wall material at the jet guard part is abraded.

To prevent such disadvantages, for example, in the injection pump shown in Austrian Patent No. 806,445, a splash plug is fitted into the flanged piston bush.

The splash stopper is made of a hardened material with a smooth polished surface so that the uncontrolled jet is first deflected and then flows into the suction chamber of the housing.

In some cases, a multi-capacity pump equipped with such a splash stopper may cause an undesirable phenomenon in which the discharge amount becomes unequal among the unit cylinders due to, for example, manufacturing errors in the stoppers.

The object of the present invention is to improve the injection pump of the type described so far with a unique configuration, thereby making it possible to dispense with the above-mentioned splash stopper as an additional component to the bushing, and, moreover, to improve its pump chamber. The purpose is to prevent wall material from being scraped by uncontrolled jets flowing out at high pressure from the pump, and also to prevent uneven discharge amounts among the cylinders in a multi-cylinder pump.

In order to solve this problem, in the present invention, the discharge hole of the bushing is perpendicular to both the axis of the piston and the common axis of the throttle hole and the suction hole. A side hole that communicates with the inside, and is controlled by a lower control edge located approximately below the second control edge of the piston so that only this discharge hole is open at the end of the injection stroke. It is said that

In the basic configuration of the present invention described above, the piston is not provided with the lower side M for the suction hole that extends straight through the flanged bush.
After passing through this suction hole, the pump
No uncontrolled jet flows into the suction chamber of the housing.

On the other hand, a lower control lip is provided on the piston as described above for the outlet hole of the bushing, which outlet opens into a lateral hole which serves as a splash protection.

In this way, as the discharge hole opens, the lower part of the piston is controlled □□
An uncontrolled jet that flows out of the pressure chamber via the rim.
After being loosely cylindrical, it flows out from the bush into the suction chamber.

By appropriately finishing the surface of the side hole of the bush,
It is possible to more effectively suppress the scraping of the wall material at the uncontrolled jet barrier inside the horizontal hole.

Since it is not difficult to make the above-mentioned horizontal holes and discharge holes with very small dimensional errors, uneven discharge amounts caused by such dimensional errors can be prevented.

Other examples of injection pumps according to the invention are also provided with an additional control lip below the first control lip of the piston.

A characteristic example of this is that the lower control edge that cooperates with the discharge hole is arranged in a staggered manner with the additional control edge that cooperates with the suction hole.

In other words, the split leg lines are at different positions by a small dimension compared to the diameter of the discharge hole in the reciprocating direction of the piston, which includes the common axis of the suction and discharge holes. The lower control edge is higher than the additional control edge.

This configuration provides the following effects.

That is, before the suction hole, which is drilled straight through the bushing, is opened for the control release stroke by means of this additional control edge, the discharge hole, which communicates with the aforementioned transverse hole, is opened. Due to the uncontrolled jet flowing out, the maximum pressure in the pump chamber has already been reliably reduced to a lower pressure.

In this way, the unrelieved high pressure from the suction hole is controlled and the jets are prevented from causing scraping of the pump housing wall.

As yet another characteristic embodiment of the present invention, there is one in which the above-mentioned horizontal hole is bored as a blind hole.

According to this configuration, swirling of fuel occurs in the suction chamber, but
It improves the mixing and thus promotes temperature equalization at each suction point of each element, and delivery unevenness between each unit cylinder is avoided very effectively.

As an example of another form according to this invention.

In some cases, the above-mentioned horizontal hole is bored as a through hole with a stepped diameter.

The arrangement results in a swirling flow of fuel within the suction chamber, although there is no appreciable general direction of flow.

This also improves the fuel mixing in the suction chamber, and also influences the flow of the control jet.

In addition, as a characteristic embodiment other than the above within the scope of the present invention, there is one in which the openings at both ends of the side hole toward the suction chamber side have different diameters.

In this case, the controlled jet flow distribution to each end can be designed to have any appropriate proportion, and when the specific shape of the suction chamber is given, the optimal flow condition can be achieved. It is.

The invention will now be described in more detail with reference to some embodiments illustrated in the accompanying drawings.

In the pump housing 1 of FIG. 1, a receiving hole 2 for a piston bushing 4 with a flange portion 3 is bored, one for each unit cylinder of the pump.

The piston 5, which is slidably fitted into the bushing 4, is actuated in a known manner by a cam drive system, not shown in the figures.

This piston (J has a total of two control edges, a first control edge 21' and a second control edge 20', on the upper side, and one lower control edge 20 on the lower side). There is.

Above the piston 5, there is a discharge valve 6 in the enlarged diameter part of the bushing's 4 axially bored holes.

This is pressed against a snap-fit sealing ring 8 in the bushing 4, with the injection conduit (not shown in the figures) being attached by a press-fit screw 7.

The bushing 4, which is placed on the upper end surface of the housing 1 with the floor plan plate 9 for adjusting the idle stroke inserted therein, is firmly attached to the housing 1 using a threaded bolt 10 fitted with a washer 12 and a nut 11. It is being

In the receiving hole 2 of the housing 1, an enlarged diameter portion surrounding the bushing 4 is formed as a suction chamber and/or an overflow chamber 13, and this chamber is sealed by upper and lower Q IJ songs 4.15. has been done.

The suction hole 16, which is bored straight through the bush 4, has an enlarged diameter portion 18 on the suction chamber side.
This is to improve the flow condition.

A discharge hole 17 facing the suction hole 16 on the opposite side communicates with a horizontal hole 19 having approximately the same diameter.

As seen in FIG. 2, in this particular embodiment, the side hole 1
9 is bored as a blind hole.

When the discharge hole 17 is opened by the lower control edge 20 of the piston 5 towards the end of the injection stroke, the flow is controlled (4 jets flow out of the pump chamber at high pressure through the discharge hole 17). It will collide with the wall of the horizontal hole 19 facing the hole 17.

As a result, most of the eruption energy is dissipated,
The fuel jet changes its flow direction toward the side hole 19.

In this way, the outflow to the suction chamber 13 is almost parallel to the wall surface of the suction chamber 13, and since the kinetic energy of the fuel jet flow has already been significantly weakened, the wall material of the housing 1 will not be scraped. There isn't.

FIG. 3 shows a flanged bushing 4 of an injection pump according to the invention, with a piston 5, the additional control edge 21 of which is located below said second control edge 21'.

By arranging the lower control edge 20 and the additional control edge 21 differently by a small dimension A compared to the diameters of the suction holes 16 and the discharge holes 17, the following effect is obtained.

That is, before the lower additional control edge 21 opens the suction hole 16, which is formed straight through the bushing 4, the pressure drop from the maximum pressure in the pump chamber to a lower pressure has already been completed. so that the uncontrolled jet flowing out through this suction hole 16 will not wear out the housing 1 of the pump.

In the bushing 4 shown in FIG. 4, the horizontal hole 19 is configured as a through hole.

According to this configuration, the uncontrolled jet flow IJ separates and advances at both outlets, and both of these branched flows flow into the suction chamber 13 through the outlet openings 22 having a larger diameter than the main body of the lateral hole 19.

This allows the uncontrolled fuel flow to better mix with the suction chamber fuel, which is normally at a different temperature, thereby reducing temperature differences in the fuel, which can cause uneven discharge between each unit cylinder. ) to eliminate the phenomenon of not sleeping.

FIG. 5 shows a bushing 4 according to another characteristic embodiment of the present invention.

In this embodiment, openings 22 at both ends of the side hole 19 on the suction chamber side,
They are constructed with different diameters.

With this configuration and/or with a configuration in which the angle of the horizontal hole 19 with respect to the piston's 5 axes and the angle with respect to the common axis of the suction hole 16 and the discharge hole 17 are arbitrarily selected, the suction Given the specific shape of the chamber, appropriate flow conditions can be achieved.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a partial vertical sectional view of an injection pump according to the present invention taken along line II in FIG.
Partial horizontal sectional view according to I--I, FIG. 3, with a piston having a lower control edge and an additional control edge which are arranged in a slightly different manner. FIG. 4 is a partial vertical sectional view of another embodiment according to the present invention, and FIG. 4 is a horizontal sectional view taken along the line ■-■ in FIG. line ■
- This is a horizontal sectional view showing yet another modification example. 1...Housing, 2...Accommodating hole for the bushing, 3...Flange part of the bushing,
4... Bush, 5... Piston, 6
...Discharge valve, 13...Suction chamber (overflow chamber), 16...Suction hole, 17...
...Discharge hole, 18... Suction chamber side enlarged diameter part of suction hole, 13... Side hole, 20... Lower control edge, 20'... upper second control edge, 21...
...Additional control edge below the first control edge, 2'1'...
. . . upper first control edge, 22 . . . opening.

Claims (1)

[Claims] 1. For internal combustion engines, the following characteristics (a, b, c, d, e): a) installed in a receiving hole made in the housing of the pump to guide histones; b) the suction hole and the discharge hole are arranged coaxially in opposing directions on the bushing; c) the piston has a first opposed control lip at its upper end; a second control edge, and a lower control edge below the second control edge; d) said suction hole cooperating with the first control edge of the piston extends through the bush; e) the discharge hole is bored in a bush so as to cooperate with the second control edge and the lower control edge of the piston; An injection pump having the above configuration, which is further characterized in that it satisfies both the following characteristics (A and I). a) The bushing 4 is provided with a horizontal hole 19 that is bored approximately perpendicularly to the common axis of the suction hole 16 and the discharge hole 17, and also approximately perpendicularly to the axis of the piston 5. The discharge hole 17 is open for communication, and (a) the configuration is controlled by the lower control edge 20 of the piston so that only the discharge hole 17 of the bushing is opened at the end of the injection stroke. 2. In the invention set forth in claim 1, the following additional features are further provided, namely: (1) said piston 5 has an additional control edge 21 which is arranged below said first control edge 21' to cooperate with said first control edge 21'; and (d) a lower part which cooperates with said discharge hole 17. The additional control edge 21 differs from the control edge 20 by a distance A in the reciprocating direction of the piston in a plane in the piston axial direction including the suction hole 16 and the discharge hole 17, and this distance A An injection pump characterized in that it is smaller than the diameter of the hole 17. 3% In the invention described in claim 1 or 2,
An injection pump characterized in that the horizontal hole 19 is bored as a blind hole. 4% In the invention described in claim 1 or 2,
An injection pump characterized in that the horizontal hole 19 is configured as a through hole with a stepped diameter. 5. In the invention according to any one of claims 1 and 2.4, the side hole 19 has openings 2 at both ends toward the suction chamber side.
An injection pump characterized in that two holes are formed to have different diameters.