DE1178251B - Device for pressure relief in fuel injection systems for internal combustion engines with injection pump and distributor - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: F02f

German class: 46 c2 - 115/02

Number: 1178 251

File number: B 58816 Ia / 46 c2

Filing date: August 2, 1960

Opening day: September 17, 1964

The invention relates to a device for pressure relief in fuel injection systems for internal combustion engines with an injection pump, which via a line containing a pressure valve and a Distributor feeds several injection nozzles one after the other.

In injection pumps of this type, the injection pump occurs at the end of each injection process with the manifold connecting line as well as in the respective the manifold with the injection nozzle connecting line pressure fluctuations caused by the running in these lines Pressure waves are generated. Depending on whether there is a pressure wave before the termination of this line could still leave or was retained in it, the residual pressure in this line is different large and thus the amount of fuel delivered from this line during the next injection process.

This disadvantage is in a known injection pump, but in which the injection pump with the manifold connecting line a pressure valve is installed, thereby reduced that the The amount of fuel that is not injected is displaced via an overflow channel into which a check valve is installed.

In the case of the injection pump described above, which has a pressure valve in the line between Pump and distributor is equipped, this disadvantage is avoided according to the invention, that separate relief outlets on the one hand for the one connecting the injection pump with the distributor Line and on the other hand for the individual lines connecting the distributor to the injection nozzles are provided, the relief outlets being controlled by the manifold so that the one relief outlet to relieve the common line with this after each injection by a Injector and before the start of the next injection by another injector in connection is set, while the other relief outlet to relieve the individual lines with each of these at least once between two successive injections by the relevant one Single line is connected.

The invention is explained by way of example with reference to the drawing.

Fig. 1 shows schematically the essential parts a first embodiment of a device according to the invention for injecting fuel in a multi-cylinder engine;

F i g. FIG. 2 shows another embodiment of the one shown in FIG. 1 shown device;

Pressure relief device at
Fuel injection systems for internal combustion engines with injection pumps and distributors

Applicant:

Societe Anonyme pour! 'Exploitation of the
Procedes Chimiques et Physiques, Zug (Switzerland)

Representative:

Dr.-Ing. W. Lampert, patent attorney,

Stuttgart W, Breitscheidstr. 4th

Named as inventor:
Pierre Etienne Bessiere,
Neuilly-sur-Seine, Seine (France)

Claimed priority:

France of August 31, 1959 (803 955)

F i g. 3 shows a further embodiment of the in FIG. 1 shown device;

Fig. 4 shows another embodiment of the Distributor of the injector shown in any one of the preceding figures.

It is assumed below that the injector injects fuel in four Makes cylinder of an engine by means of a single pump arrangement with piston and cylinder.

The piston 1 of the pump controls the start of the effective delivery by closing the inlet line 3, while he is the end of the injection period by reopening this line effected by means of a control edge 4 forming a curved path; this edge delimits one in the piston 1 incised groove 5, which is connected to the interior of the cylinder 2 by a channel 6 is. To change the delivery rate of the pump, the piston 1 can be rotated about its axis. Of the Piston is z. B. driven by a cam.

The cylinder 2 is also equipped with a pressure valve 7 (which, for example, can have the shape of a sphere) and a delivery line 8 is provided. The pump can also have two pistons rotating in opposite directions and one common Cylinders are formed.

409 687/83

The delivery line 8 is connected to a distributor housing 9, in the bore 9 a of which a slide 10 rotates.

The rotary valve 10 connects during each of the successive delivery strokes of the piston 1 of the pump, the conveying line 8 in succession with a certain number of not shown injection nozzles via individual lines 11a, 11b, etc., which are connected to the manifold. 9 The successive connections are made by means of a groove 12 in the side surface of the rotary valve 10, which opens into an annular groove 13; this is at the point at which the delivery line 8 opens into the bore 9 α.

For such a device to work properly, it is essential that the pressures, soft immediately before each injection period in the one connecting the pump to the various injection nozzles Lines prevail, from one injection period to the next for all injectors at least are approximately the same. However, it is not necessary that the in these lines between the successive injection periods prevailing pressure over the entire length of the lines the same Has value. On the contrary, it is often useful in the various sections of this line to have different pressures.

So it is often useful between two successive injection periods in the common To maintain a higher pressure in the delivery line 8 than in the individual lines 11a, life, etc.

If a back suction valve is switched on in each individual line, the pressure upstream of this valve should be be so low that the suck back valve closes quickly.

In order to meet these different conditions, according to the invention, separate outlets are provided on the one hand for the common line 8 and on the other hand for the individual lines 11a, 116, etc. These separate outlets can be controlled by the distributor itself, in such a way that after each injection period on the one hand line 8 and on the other hand at least that individual line 11a, Hb , etc. through which the previous injection took place are connected to outlet spaces via different routes will.

For this purpose, as many grooves 14 are made in the surface of the rotary valve 10 lying to the left of the annular groove 13, as there are injection periods during a complete revolution; In the swept by these grooves 14 zone of the bore 9 a opens a relief outlet line 15. The distribution of the grooves 14 on the circumference and the location of the mouth of the line 15 in the wall of the bore 9 α are with respect to the position of the groove 12 and of the mouths of the individual lines 11a, 11b etc. are selected so that the delivery line 8 is connected to the outlet line 15 between two successive injection periods.

So that the pressure maintained in the line 8 is higher than that in the space to which the line 15 leads, either a throttle point 16 or a check valve 17 is in this line (see Fig. 2) are provided, the dimensioning or setting of which determines the residual pressure in the line 8.

For emptying the individual lines 11 a, 11 b etc., a second annular groove 18 and between the two annular grooves 13 and 18 a further longitudinal groove 19 are provided in the rotary valve of the distributor, which opens into the annular groove 18 and extends into the zone in which are the mouths of the individual lines 11 a, 11 b , etc. The groove 19 lies in a radial plane which, with respect to the direction of rotation, is behind the radial plane in which the groove 12 lies. The distance between these two grooves is chosen so that after the end of the injection period through a certain individual line and before the start of the next injection period through the same individual line, this is connected through the groove 19 and the annular groove 18 to a relief outlet line 20, which is connected by the outlet line 15 is different.

In this line 20, either a throttle point 21 or a check valve 22 is provided in order to maintain a residual pressure in each individual line 11a, lib , etc. between two injections, which is the same for all individual lines but is different from the residual pressure in line 8. By maintaining a lower pressure in the individual lines, interference injections are avoided. On the other hand, a high residual pressure in the common line 8 causes an automatic change in the start of injection in the correct sense, since the lower the drive speed of the pump, the later the injection begins.

As already mentioned, it may be expedient not to provide any devices corresponding to the throttle point 21 or the calibrated valve 22 in the outlet line 20, which devices generate a considerable residual pressure in the section of the line 20 located upstream of these devices. This is e.g. B. the case when back suction valves 23 (see Fig. 3) are provided in the individual lines 11a, 11b, etc. If such valves are provided in the individual lines, it is useful to promote the rapid closure of the same as possible. The lower the pressure in front of these valves, the faster this closure takes place. These valves maintain the desired residual pressure between them and the corresponding injection nozzles.

The in F i g. 4 differs from the distributor shown in FIG. 1 in that it has as many grooves 19a as there are individual lines 11a, 11b , etc. The distribution of these grooves 19 a on the rotary valve 10 is such that after each injection period, all the individual lines are connected to the outlet line 20 and to each other at the same time through a single line. The position of the grooves 19a on the circumference of the rotary valve 10 must then be selected so that the connection between the individual lines and the outlet line takes place between two successive injection periods.

The invention can of course be modified. So z. B. the residual pressure in the common line 8 and / or in the individual lines 11a, Ub etc. can be produced by means of a pump with continuous delivery (z. B. a gear pump), the delivery side of which is connected to the corresponding outlet line and a pressure on the desired Contains adjusted exhaust valve. Furthermore, the grooves 14, 12, 19 and 19 a provided on the cylinder surface of the rotary slide valve 10 of the distributor can be at least partially replaced by channels located inside the distributor, which one-

on the one hand with the provided on this annular grooves 13 or 18 in connection and on the other hand in the Surface of the distributor rotary valve open through radial branches which are in the plane of the lines that are to be connected to the ring grooves at the desired moment. Further the piston of the pump can simultaneously form the distributor, in which case it then executes a movement, which consists of an axial alternating movement and a rotary movement about its axis, wherein then the delivery rate is regulated in a different way than by a curved track 4.

Claims (6)

Patent claims: 1. A device for pressure relief in fuel injection systems for internal combustion engines with an injection pump which feeds several injection nozzles one after the other via a line containing a pressure valve and a distributor, characterized in that separate relief outlets on the one hand for the line connecting the injection pump to the distributor (8) and on the other hand for the individual lines (11a, etc.) connecting the distributor to the injection nozzles are provided, the relief outlets being controlled by the distributor so that the one relief outlet (15) to relieve the common line (8) with this after each injection through a Injection nozzle and before the start of the next injection is connected by another injection nozzle, while the other relief outlet (20) for relieving the individual lines (Ha , etc.) with each of them at least once between two successive injections by the concern de individual line is connected. 2. Apparatus according to claim 1, characterized in that both the relief outlet (15) for the common line (8) and for the individual lines (11 α , etc.) contain devices (16, 21; 17, 22) which in maintain the desired pressures in these lines. 3. Apparatus according to claim 2, characterized in that the devices which the desired pressures on the one hand in the common line (8) and on the other hand in the individual lines (Ha, etc.) are maintained so that the pressure in the common Line is larger than that maintained in the individual lines. 4. Apparatus according to claim 1, characterized in that the relief outlet (15) for the common line (8) contains devices, which a desired pressure in this maintained, while the relief outlet (20) of the individual lines (Ha, etc.) no such Contains devices, the individual lines each being provided with a back suction valve (23) are. 5. Device according to one of claims 1 to 4, characterized in that the distributor has two grooves (13, 18), one of which (13) on the one hand with the common line (8) and on the other hand with a groove (12) od . The like. Which connects the groove one after the other with the various individual lines (Πα etc.), and with a certain number of grooves (14) or the like. Which connect the groove to the relief outlet (15) of the common line (8) , while the other groove (18) on the one hand with at least one groove or the like (19), which connects the groove in succession with each individual line (Ua , etc.) in the period between two injections through the same individual line, and on the other hand is in communication with the relief outlet (20) for the individual lines. 6. Apparatus according to claim 5, characterized in that with the relief outlet (20) of the individual lines (11a , etc.) in communication groove (18) of the distributor at the same time with as many grooves (19a) od how individual lines are present, these latter grooves establishing the connection between the groove and the individual lines in each period between two successive injection periods from two different injection nozzles. Considered publications:
U.S. Patent Nos. 2,372,559, 2,385,089. 1 sheet of drawings 409 687/83 9.64 © Bundesdruckerei Berlin