DE19916965A1 - Fuel injection system for IC engine has the injectors opened by the pressure in the fuel line and with control valves separate from the injectors - Google Patents

Abstract

A fuel injection system for an IC engine has each injector connected to a common rail by a control valve (4') separated from the injector by a fuel line (3). The injector includes a spring loaded valve element that is opened by the pressure in the fuel line. A return feed (15) with a flow restriction (16) dumps excess fuel back into the fuel tank. The control valve is operated by a solenoid, a piezoelectric element or by a magnetostrictive element, and is mounted away from the thermal effects from the engine.

Description

The invention relates to an injection system, in particular for a common-rail distillery that works according to the Otto principle engine with internal mixture formation, after the closer defined in the preamble of claim 1 ten Art.

A generic injection system is from DE 195 48 526 A1 known. Here, an electro mechanical converter device, for example one magnetostrictive or a piezoelectric pre direction, can be achieved that the injection valve of the Injection system can be controlled precisely and quickly can.

The one used in this injection system spray valve is disadvantageous, however, that in an Er heating the electromechanical transducer  thermal expansion other than the housing of the Injector has. This results in changing temperatures different strokes the valve needle of the injection valve, creating a exact injection quantity only with great effort can be held.

Another disadvantage of the known injection valve is the construction-related length, which a correspondingly large installation space within one Internal combustion engine requires.

It is therefore an object of the present invention To create injection system by means of which one on the one hand fuel very precisely and with high pressure can be injected, and which on the other hand for series production is well suited. Furthermore the injection system according to the invention should be as possible little space in or on an internal combustion engine Claim.

According to the invention, this task is characterized by the drawing part of claim 1 mentioned features solved.

By the directional control valve according to the invention, which directly to open the valve body via the fuel pressure is provided, there is a greatly reduced Sensitivity to thermal expansion within the Injector, because the directional valve as a component for Control of the injection no longer physically with the injector must be connected and therefore not whose thermal expansion is exposed.  

Furthermore, the structure according to the invention a less complicated and therefore cheaper Fer the entire injection system with Wegeven til and the injection valve possible and it results by separating the two components, a total greatly reduced overall length of the injection valve, where through this a correspondingly reduced installation space needed.

Furthermore, the A according to the invention enables spraying system compared to conventional electro magnetic injectors higher injection pressures as well as improved dynamics and thereby shortened Dead times.

If the Erfin a magneto for the actuation of the directional valve strict, piezoelectric or electromagnetic Actuator is provided, so the length of such an actuator for the directional control valve can be reduced and it advantageously results an even smaller installation space for the injection system or on an internal combustion engine.

Further advantageous embodiments of the invention result from the remaining subclaims as well from the following in principle with reference to the drawing illustrated embodiments.

It shows:

Fig. 1 a first embodiment of the inventive SEN injection system with a 2/2-way valve;

Figure 2 shows a second embodiment of the injection system according to the invention with a 2/2-way valve and a return line;

3 shows a third embodiment of the erfindungsge MAESSEN injection with a 4/2-Wegeven til and a return line.

Fig. 4 shows a fourth embodiment of the injection system according to the invention with a 2/2-way valve, a return line and an additional supply line; and

Fig. 5 shows a fifth embodiment of the injection system according to the invention with a 2/2-way valve, a return line and two supply lines.

Fig. 1 shows an injection system 1 with an injection valve 2 , which is connected via an inlet line 3 directly to a directional valve 4 , in this case a 2/2-way valve 4 '. The feed line 3 is used to supply fuel to the injection valve 2 and is based on a fuel tank, not shown. The injection system 1 is intended for use in a gasoline internal combustion engine, not shown, in this case a common rail internal combustion engine with internal mixture formation.

The 2/2-way valve 4 'is of a design known per se and for this reason is only shown schematically in the figures. In the state shown in FIG. 1, the 2/2-way valve 4 'is in the blocking position. In order to bring the 2/2-way valve 4 'into its flow position or open position, a control slide, not shown, is moved. The supply line 3 is thus disconnected and fuel can flow through a housing 5 of the injection valve 2 into a working chamber 6 which is formed within the housing 5 . The 2/2-way valve 4 'is not physically connected to the housing 5 , as a result of which it is not exposed to the thermal expansion thereof.

In the working chamber 6, a valve needle and a valve body 7 is mounted, which has at one end a valve member. 8 The valve member 8 is provided for sealing contact with a valve seat 9 of the housing 5 , an opening 10 of the housing 5 being closed by the valve member 8 .

If fuel is introduced into the working chamber 6 , a pressure is formed there, which lifts the valve member 8 from the valve seat 9 and thus opens the opening 10 for the fuel to exit. In order to be able to close the opening 10 again after the fuel pressure has been reduced, a spring device 11 is provided which is arranged in the working chamber 6 . The Fe dereinrichtung 11 , in this case a helical spring, is supported on one side on the housing 5 and on the other side on a nut 12 which is screwed onto a thread 13 of the valve body 7 .

In order to maintain better guidance for the valve body 7 , it is guided in the lower region of the working chamber 6 by two annular guide elements 14 arranged one behind the other in the axial direction.

The injection valve 2 is operated for injecting fuel into combustion chambers (not shown) of the internal combustion engine as follows: the 2/2-way valve 4 ', which can also be referred to as a servo valve, is used in a manner not shown, for. B. piezo electrically or electromagnetically actuated and switched to its open position, whereby fuel can flow through the feed line 3 into the working chamber 6 men. An actuator required for this is not shown in the figures. The fuel pressure causes a force on the valve member 8 which is oppositely directed to the force generated by the spring device 11 . If the force generated by the fuel pressure rises above that of the spring device 11 , the valve member 8 lifts outward from its valve seat 9 and opens the opening 10 , where fuel can flow out and is injected into the corresponding combustion chamber.

As soon as the 2/2-way valve 4 'is switched into its blocking position, the fuel pressure drops and the valve member 8 closes the opening 10 by the force of the spring device 11 , as a result of which the fuel injection is ended. The injection of fuel is thus completely regulated via the 2/2-way valve 4 '.

In Fig. 2, a further embodiment of an injection system 1 is shown, the structure corresponds in principle to that shown in Fig. 1. All goes out of the working chamber 6 a Rücklauflei device 15 in which there is an adjustable Dros selelement 16 . Via the return conduit 15, the pressure in the working chamber 6 immediately after the injection, that is, the valve 4 'degraded more rapidly after the closing of the 2/2-way, whereby a Besse res response of the valve member 8, in particular during the closing process, and thus a more favorable course of the fuel injection is reached. The fuel is, as is common in common rail internal combustion engines, leads from the return line 15 directly into the fuel tank, if not shown.

The throttle element 16 ensures that sufficient pressure is built up in the working chamber 6 when the 2/2-way valve 4 'is opened. Furthermore, the throttle element 16 determines the closing speed of the valve member 8 .

Fig. 3 shows a further injection system 1 with ähnli chemical structure as shown in Fig. 1 and Fig. 2, wherein a / 2-way valve is 4 "provided in the inlet pipe 3 here 4. The opening of the valve member 8 from the valve seat 9 is analogous to the embodiments of FIGS. 1 and Fig. 2, however, the return line 15 is also connected to the 4/2-way valve 4 "connected, so that the entire injection process including the return of the fuel via the 4/2-way valve 4" ge The 4/2-way valve 4 "can thus assume a blocking position and a flow position, with the return line 15 in the blocking position and the inlet line 3 in the flow position being switched to flow.

Thus, since the return line 15 is closed when fuel flows into the working chamber 6 , the pressure cannot decrease, which inevitably leads to pressure reduction by opening the valve member 8 and thus to fuel injection into the combustion chambers.

According to FIG. 4 is Darge provides another injection system 1, in which the valve member 8 is connected via the valve body 7 having an actuator 17th Branches off from the feed line 3, an additional to line 18 via the 2/2-way valve 4 'from a door element actuator chamber located above the designed as actuator piston Aktua 17 19, the actual feed line 3 while directly into the working chamber 6 runs and thus to the Valve element 8 constantly the system pressure is present. From the Ak tuatorkammer 19 leads as in the injection system 1 according to FIG. 2, the return line 15 in the rail, not shown in this case or the fuel tank back. The actuator chamber 19 is sealed off from the working chamber 6 by means of the actuator element 17 .

Due to the size of the areas below the Aktuatorele element 17 and the valve member 8 or valve seat 9 , the valve member 8 is held in its closed position by the fuel pressure applied via the inlet 3 in the working chamber 6 . This is the case because the area underneath the actuator elements 17 is greater than that acting surface over wel che the pending through the inlet line 3 into the working chamber 6 fuel on the valve member. 8

However, if the 2/2-way valve 4 'is actuated and brought into its flow position, then pressure is applied to the actuator element 17 via the additional supply line 18 by means of introduced fuel, which is due to the actuator chamber 19 sealed against the working chamber 6 for opening of the valve member 8 leads over the valve body 7 . In this way, the fuel flowing into the working chamber 6 via the feed line 3 is injected into the combustion chambers.

In the return line 15 there is in turn the throttle element 16 , as a result of which sufficient fuel pressure can be built up in the actuator chamber 19 . Furthermore, the throttle element 16 again determines the closing speed of the valve member 8 . The throttle element 20 in the inlet line 18 determines the opening speed of the valve member 8 .

When you press the 2/2-way valve 4 'in its Ge closed position, no more fuel is introduced via the inlet line 18 , the pressure in the actuator chamber 19 builds up via the return line 15 and the valve member 8 is beitskammer by the pressure in the Ar 6, as well as the force of the Federein device 11 also present here and acting on the actuator element 17 in its closed position, whereby the injection process is ended.

Fig. 5 shows a further embodiment of an injection system 1 , in which the feed line 3 just opens directly into the working chamber 6 . It is in turn mounted the actuator 17 to the valve body 7, the actuator chamber 19 is, however, in an upper chamber 19a and a lower chamber 19 separates b ge. In this case, there is no connection between the lower chamber 19 b and the working chamber 6 and the constant pressure in the feed line 3 does not therefore act on the actuator element 17 . In addition, the upper chamber 19 a is separated from the lower chamber 19 b by a seal on the actuator element 17, not shown.

However, again the additional feed line 18 is provided, which branches off from the feed line 3 and leads directly to the lower chamber 19 b. In the additional inlet line 18 , the throttle element 20 is also provided in this embodiment. From the lower chamber 19 b, the return line 15 with the adjustable throttle element 16 located therein starts, specifically to the 2/2-way valve 4 '.

The function of the injection system 1 is as follows in this case: in the illustrated closed Stel development of the 2/2-way valve 4 'is connected via the additional supply line 18 is a pressure in the lower chamber 19 b of which, due to the area ratios of Ak tuatorelement 17 and valve member 8, as shown in FIG. 4, in spite of the pressure in the working chamber 6, the Maximum closed senstellung of the valve member 8 causes.

If the 2/2-way valve 4 'is now switched into its flow position and thus the return line 15 is released, the fuel flows via the additional supply line 18 with the throttle element 20 , the lower chamber 19 b, the return line 15 with the throttle element 16 and the 2/2-way valve 4 'back into the rail or the tank. As a result, the pressure acting on the actuator element 17 drops. In this case, the pressure of the fuel supplied via the feed line 3 to the working chamber 6 is sufficient to lift the valve member 8 from its valve seat 9 against the force of the spring device 11 , to open the opening 10 and thus to provide a fuel injection. This injection can be ended again by closing the 2/2-way valve 4 '.

Claims (16)

1. Injection system, in particular for a gasoline-working common rail internal combustion engine with internal mixture formation, with an injection valve, which has a valve body, through which a formed by a housing of the injection valve and with pressurized fuel Workable chamber can be closed and which has at one end a valve member for sealing contact with a valve seat, the valve member lifting outwards from the valve seat and opening an opening for fuel injection, characterized in that the injection valve ( 2 ) at least one directional valve ( 4 ) for opening the valve member ( 8 ) is connected, the valve member ( 8 ) opening by the pressure of the fuel. 2. Injection system according to claim 1, characterized in that a magnetic tostrictive, piezoelectric or electromagnetic actuating element is provided for the actuation of the directional valve ( 4 ). 3. Injection system according to claim 1 or 2, characterized in that an inlet line ( 3 ) for the supply of fuel in the working chamber ( 6 ) is provided. 4. Injection system according to claim 1, 2 or 3, characterized in that the directional valve is designed as a 2/2-way valve ( 4 '). 5. Injection system according to one of claims 1 to 4, characterized in that from the working chamber ( 6 ) of the injection valve ( 2 ) is a return line ( 15 ) for the fuel. 6. Injection system according to claim 5, characterized in that a throttle element ( 16 ) is arranged in the return line ( 15 ). 7. Injection system according to claim 1, 2 or 3, characterized in that the directional control valve is designed as a 4/2-way valve ( 4 "). 8. Injection system according to claim 7, characterized in that from the working chamber ( 6 ) of the injection valve ( 2 ) a return line ( 15 ) for the fuel to the 4/2-way valve ( 4 "). 9. Injection system according to one of claims 1 to 8, characterized in that an actuator element ( 17 ) for opening the valve member ( 8 ) is arranged on the valve body ( 7 ). 10. Injection system according to claim 9, characterized in that an actuator chamber ( 19 ) is arranged between the actuator element ( 17 ) and the housing ( 5 ). 11. Injection system according to claim 10, characterized in that an additional inlet line ( 18 ) in the Aktua gate chamber ( 19 ) opens, and that from the actuator chamber ( 19 ) the return line ( 15 ) starts. 12. injection system according to claim 10, characterized in that the actuator chamber (19) into an upper chamber (19 a) and a lower chamber (19 b) is subdivided, wherein the actuator element (17) between the chambers (19 a, 19 b) located. 13, injection system according to claim 12, characterized in that an additional feed conduit (18) opens out (19 b) in the lower chamber, and that the return line (15) extending from the lower Kam mer (19 b). 14. Injection system according to one of claims 9 to 13, characterized in that the valve member ( 8 ) by the size of the surfaces of the actuator element ( 17 ) and the valve member ( 8 ) and the force acting on these surfaces fuel pressure is held in its closed position. 15. Injection system according to one of claims 1 to 14, characterized in that the valve member ( 8 ) is held in its closed position by a spring device ( 11 ). 16. Injection system according to one of claims 1 to 15, characterized in that on the housing ( 5 ) in the working chamber ( 6 ) Füh approximately elements ( 14 ) for the valve body ( 7 ) are arranged.