GB2327713A

GB2327713A - Direct-injection fuel injection valve with solenoid valve control for a multicylinder i.c. engine

Info

Publication number: GB2327713A
Application number: GB9815794A
Authority: GB
Inventors: Ulrich Augustin
Original assignee: Daimler Benz AG
Current assignee: Daimler Benz AG
Priority date: 1997-07-25
Filing date: 1998-07-20
Publication date: 1999-02-03
Anticipated expiration: 2018-07-20
Also published as: ITRM980487A1; FR2766523A1; DE19732070A1; IT1299574B1; FR2766523B1; GB9815794D0; DE19732070C2; GB2327713B; ITRM980487A0

Abstract

The valve 1 has a housing with a stepped bore 3 containing a longitudinally displaceable control piston 5 and a smaller diameter valve body 4 designed as a valve piston which cooperates with the control piston 5. The control piston 5 and valve body 4 have aligned passage bores 7, 8. A high-pressure conduit 11 leads to the valve body 4 and, when the valve body 4 is opened, can be connected to a supply conduit 16 opening into a pressure chamber 17 surrounding a nozzle needle 6. A passage bore 7,8 runs through the control piston 5 and valve body 4 via which a control space 9 delimited by the control piston 5 is constantly connected to the high pressure conduit 11. Due to an inflow throttle 10, when the control space 9 is relieved by means of the injection-influencing solenoid valve 26, the valve body 4 is lifted from its seat 12. A return conduit 22 has a throttle point 19 so that during injection a relief connection from the supply conduit 16 to the return conduit 22 is interrupted by movement of the valve body 4.

Description

1 Directinjection fuel injection valve with solenoid valve control 2327713

The invention relates to a direct-injection fuel injection valve with solenoid valve control for a multi-cylinder internal combustion engine, with a control piston and a valve body cooperating with the latter and located in a valve housing, with a high-pressure conduit which leads to the valve body and, when the valve body is opened, can be connected to a supply conduit opening into a pressure chamber surrounding a nozzle needle, and with a passage bore which runs in the control piston and valve body and via which a control space delimited by the control piston is constantly connected to the high-pressure conduit, with an inflow throttle being interposed, the pressure-loaded control space being capable of being relieved by means of the injection-influencing solenoid valve, furthermore with a return conduit having a throttle point.

A fuel injection valve of this type with solenoid valve control is known from DE 196 12 738 AI, in which the control piston, together with an integrated valve body, is guided in two housing parts and is directly connected to the rear side of the nozzle needle. The valve body is surrounded by an annular space, into which opens, on the one hand, the supply conduit and, on the other hand, a throttle return conduit.

In systems of this type, the high-pressure conduit leading to the injection nozzle is permanently relieved by means of the throttle return, in particular due to the constant connection between the supply conduit and the return conduit via the annular space.

The present invention seeks, by means of measures involving little outlay in terms of construction on each fuel injection valve, to ensure that the overall efficiency of the injection system can be improved substantially.

According to the present invention there is provided a direct-injection fuel injection valve with solenoid valve control for a multi-cylinder internal combustion engine, with a control piston and a valve body cooperating with the latter and located in a valve housing, with a highpressure conduit which leads to the valve body and, when the valve body is opened, can be connected to a supply conduit opening into a pressure chamber surrounding a nozzle needle, and with a passage bore which runs in 2 the control piston and valve body and via which a control space delimited by the control piston is constantly connected to the high-pressure conduit, with an inflow throttle being interposed, the pressureloaded control space being capable of being relieved by means of the injection- influencing solenoid valve, furthermore with a return conduit having a throttle point, wherein, during injection, a relief connection from the supply conduit to the return conduit is interruptable by means of the valve body.

Advantageous developments of the invention are also specified in the subclaims.

Permanent relief during injection is avoided by means of the measures according to the invention, in particular due to the controllable connection between the supply conduit leading to the injection nozzle and the return conduit connected to the low-pressure system, that is to say relief takes place only between injections, not during injections. The return quantity is thus reduced considerably.

The invention is illustrated in the drawing and is explained in more detail below with reference to two embodiments. In the drawing:

Figure 1 shows a longitudinal section through the fuel injection valve according to the invention, Figure 2 shows a greatly enlarged sectional illustration of the upper region of the fuel injection valve, and Figure 3 shows an enlarged illustration of another embodiment of the fuel injection valve, specifically, once again, the upper region. A direct- injection fuel injection valve 1 with solenoid valve control, according to Figure 1, which is preferably used for accumulator-type injection systems of multi-cylinder internal combustion engines, the said systems working on the common rail principle, is composed of a mufti-part valve housing 2, of a control piston 4 guided so as to be longitudinally displaceable in a stepped cylindrical recess 3 of the valve housing 2, of a valve body 5 cooperating with the said control piston and of a springloaded nozzle needle 6 spatially separated from the valve body 5 and control piston 4.

The valve body 5 is designed as a valve piston and lies coaxially with the control piston 4 of larger diameter, which has a passage bore 7 which a passage bore 8 arranged in the valve body adjoins. The control piston 4 and valve piston 5 are both accommodated in the one-part housing part of the valve housing 2.

3 The control piston 4 delimits, on its rear side, a control space 9 into which opens an inflow throttle 10 of the passage bore 7. Due to the arrangement of the inflow throttle 10, when the control space 9 is relieved a higher pressure than in the control space 9 is established at the high-pressure end of the valve piston, the said higher pressure causing the valve body 5 to be lifted off from its valve seat 12. - The control space 9 is connected, via the two passage bores 7, 8 lying coaxially with one another, to a high-pressure conduit 11 running radially in the valve housing 2. The valve piston is provided with a conical seat surface 13 matched to the conical valve seat 12 in the valve housing 2.

A cylindrical tenon 14 formed on the valve piston adjoins this conical shape and delimits an annular space 15, from which a supply conduit 16 leads away, the said conduit opening into a pressure space 17 surrounding the spring-loaded nozzle needle 6.

According to Figure 2, the supply conduit 16 has a branch 18 with a system relief throttle 19 which cooperates with a circumferential groove 20, worked in the upper region of the valve piston 5, with an opening or closing effect. The circumferential groove 20 is connected to a return conduit 22 via an annular interspace 21.

The interspace 21 is formed in equal parts by a shoulder 23 in the control piston 5 and a shoulder 24 in the valve piston 4 and is designed to be -3 substantially larger than the circumferential groove 20.

In the position illustrated, the valve piston 5 resting on the valve seat 12 makes an open relief connection from the supply conduit 16, via the system relief throttle 19, circumferential groove 20 and interspace 2 1, to the low-pressure-side return conduit 22.

As soon as the control space 9 connectable to a relief conduit 25 is relieved by activating the solenoid valve 26 (Figure 1), the valve piston 5 lifts off from its valve seat 12 due to the higher pressure prevailing at the tenon 14 of the valve piston 5 and the lower control edge 20a of the circumferential groove 20 runs over the system relief throttle 19, thereby interrupting relief during injection.

In contrast to the system relief throttle 19 and circumferential groove 20, the annular interspace 21 and return conduit 22 are constantly connected to one - 1 __---1 11) 4 another, irrespective of the particular position of the valve piston 5.

According to Figure 3, the system relief throttle 19 is not located in the valve housing 2, but in the valve piston 5, and is connected to a longitudinal bore 27 leading into the annular interspace 21 and running in the valve piston 5.

At a short distance from the tenon 14, the system relief throttle 19 runs radially and can be connected to the annular space 15 only when the valve piston 5 is in the closing position. The mouth cross-section 19a of the system relief throttle 19 is located in the upper region of the annular space 15, in such a way that, even after a small opening stroke of the valve piston 5, the relief connection is cancelled.

Claims

1. A direct-injection fuel injection valve with solenoid valve control for a multi-cylinder internal combustion engine, with a control piston and a valve body cooperating with the latter and located in a valve housing, with a high- pressure conduit which leads to the valve body and, when the valve body is opened, can be connected to a supply conduit opening into a pressure chamber surrounding a nozzle needle, and with a passage bore which runs in the control piston and valve body and via which a control space delimited by the control piston is constantly connected to the high-press ure conduit, with an inflow throttle being interposed, the pressureloaded control space being capable of being relieved by means of the injection-influencing solenoid valve, furthermore with a return conduit having a throttle point, wherein, during injection, a relief connection from the supply conduit to the return conduit is interruptable by means of the valve body.

2. A fuel injection valve according to Claim 1, wherein the relief connection is a system relief throttle.

3. A fuel injection valve according to Claim 2, wherein the system relief throttle is arranged in the valve housing in a branch of the supply conduit and only in the injection intermission is connected to the return conduit via a circumferential groove provided on the control piston.

4. A fuel injection valve according to Claim 2, wherein the system relief throttle is provided in the valve body and only in the injection intermission can be connected to an annular space surrounding the valve body in the valve- seat region, in such a way that there is a relief connection from the supply conduit opening into the annular space, via the system relief throttle and a longitudinal bore running in the valve body, to the relief conduit.

5. A fuel injection valve according to Claim 1, wherein the control piston, the valve body of smaller diameter and their passage bores lie coaxially with one 6 another, mutually confronting end faces of the control piston and valve body being pressed one onto the other, so as to seal off the passage bores, and, of the passage bores, that one arranged in the control piston has an inflow throttle at its end located on the control-space side.

6. A fuel injection valve according to any one of the preceding claims, wherein the control piston and valve body together form, in the region of their mutually confronting end faces, an annular interspace which is connected to the return conduit in each position of the control piston.

7. A fuel injection valve according to Claims 3 or 4 and 5 and 6, wherein the shallow circumferential groove or the longitudinal bore running in the valve body leads into the annular interspace.

8. A direct-injection fuel injection valve substantially as described herein with reference to and as illustrated in the accompanying drawings.

1 Amendments to the claims have been filed as follows 1. A direct-injection fuel injection valve with solenoid valve control for a multi-cylinder internal combustion engine, with a control piston and a valve body cooperating with the latter and located in a valve housing, with a high- pressure conduit which leads to the valve body and, when the valve body is opened, can be connected to a supply conduit opening into a pressure chamber surrounding a nozzle needle, and with a passage bore which runs in the control piston and valve body and via which a control space delimited by the control piston is constantly connected to the high-press ure conduit, with an inflow throttle being interposed, the control space being pressure loaded being capable of being relieved by means of the injection- influencing solenoid valve, furthermore with a return conduit which is associated with the valve body, wherein, during injection, a relief connection between the supply conduit and the return conduit is interruptable by means of the valve body.

5. A fuel injection valve according to Claim 1, wherein the control piston, the valve body of smaller diameter and their passage bores lie coaxially with one another, mutually confronting end faces of the control piston and valve body being pressed one onto the other, so as to seal off the passage bores, and, of the passage bores, that one arranged in the control piston has an inflow throttle at its end located on the control-space side.

7. A fuel injection valve according to Claims 3, 4, 5 or 6, wherein the shallow circumferential groove or the longitudinal bore running in the valve body leads into the annular interspace.