DE19956598A1 - Valve for controlling liquids - Google Patents

Abstract

The invention relates to a valve for controlling liquids, comprising a first valve element (6), which controls the impingement of a pressure upon a high-pressure chamber (15), a control element (3), which controls the actuation of the first valve element (6) and a second valve element (8), which controls the impingement of a pressure upon a valve member (26). According to the invention, the control element (3) is configured as a piezo actuator and also controls the actuation of the second valve element (8).

Description

State of the art

The invention relates to a valve for controlling liquid keiten according to the preamble of claim 1.

EP 0 477 400 A1 describes a valve which is common today wrote. There is a stepped hole in the valve housing ses an actuating piston of the valve member in one part the small diameter stepped bore is slidably attached arranges. A larger piston that can be moved by a piezo actuator ben is larger in part of the stepped bore Diameter arranged. There is a between the two pistons hydraulic pressure chamber filled with a pressure medium trained so that a hydraulic translation of a Movement of the piezo actuator takes place. That is, if the larger one Piston through the piezo actuator by a certain distance is moved, the actuating piston of the valve member one around the ratio of the piston diameters increased stroke because the piston of the piezo actuator has a larger Surface as the actuating piston of the valve member. The valve member, the actuating piston of the Valve member, the piston moved by the piezo actuator and the piezo actuator in a row on a common axis. Furthermore, from the generic publication US 5,738,071 with a hydraulically operated fuel injector  an injector housing known, which one Has hydraulic fluid inlet and a needle control chamber. A hydraulic unit inside the injector leads Fuel to the injector housing under pressure. The Hydraulic unit includes an electromagnetically operated Control valve for the hydraulic fluid and can Open and close hydraulic fluid inlet. On Needle valve element comprises the pressure of the needle Hydraulic closing surface exposed to the control chamber. Additional is a needle control using the electromagnet valve provided, which is mounted in the injector housing and the needle control chamber with a high pressure fluid source connect or shut off. This enables slow response of the hydraulic fluid control valve direct control of the fast responding needle vein tils thanks to the only fast-acting elec tromagnets.

However, this system is disadvantageous in that only that Control pressure side is controlled. In other words, in the case of such a System that represents high efficiency and high pressure generated only very locally, a small pre-injection quantity to represent, is a second control on the High pressure side necessary. Two such controls are each but very critical in the energy balance of the control unit watch.

Advantages of the invention

The valve according to the invention with the characteristic feature len of claim 1 has the advantage that by controlling the two controls by the Piezo actuator can only be supplied to the system once must, so that the energy balance towards a low Power consumption can be optimized. The use of a only control element as a sequential control  also a simple structure and thus a smaller war cost and cost framework of the entire system.

In a particularly advantageous embodiment, these are first and second valve element connected in series, whereby the space requirement of the three components, d. H. of the piezo actuator as well as the first and second controls on a mini mum is reducible, since the first control as an actuator serving organ of the second valve element. Hence is no additional actuating element between the piezo actuator and second valve element necessary.

It is advantageous between the first and second valve ment provided a gap. In this way, the first can Valve element and then the second valve element switched become. In other words, it's a circuit of the first Valve element without simultaneous switching of the second Valve element possible.

Is preferred between the first valve element and the High pressure room arranged a first control room, which can be acted upon by pressure from a control rail. The Control room enables an adequate transmission pressure applied via the first valve element the high pressure room. Here, the first control room can Perform pressure translation from the control rail to the high pressure room ren. That is, depending on the requirements, the tax rail predetermined pressure with a suitable translation ratio Ratio, about 1: 3 transferred to the high pressure room who the. Of course, the degree of transmission, depending on which it is filling requirements freely selectable.

To reduce the pressure in the first control room To be able to introduce the first control room is advantageous ter way to open with a through the first valve element connected or closable leakage oil channel. So can  depending on the position of the first valve element, a high pressure generated in the first control room and consequently in the high pressure room or the pressure in the control room and thus in the high-pressure room be stretched.

In another particularly advantageous embodiment form is between the second valve element and the valve member arranged a second control room, which in turn is pressurized by the control rail. Hereby can both control rooms with the same, in the control rail existing pressure can be applied.

Analogous to the first control room, the second control room is included an outlet throttle connected by the second Ven tilelement is opened or closed. this makes possible varying the pressure in the second control room and thus the application of pressure to the valve member.

Preferably in the valve according to the invention Control liquids the control rail with a decentra len control pressure pump connected, depending on the requirements system offers the possibility of only that valve according to the invention for controlling liquids replace, but the same decentralized control pressure pump maintain. It also allows the separation between the egg General valve for controlling liquids and the de central control pressure pump a better use of space in the With regard to the respective assembly conditions.

The first control chamber and / or second is / are Control room trained as a hydraulic translator. Hydrau The translators are of various dimensions rations and translation ratios inexpensively Lich and also lead to a simple structure of the entire valve.

drawing

In the drawing is an embodiment of the invention shown. The embodiment will follow in the the description explained in more detail. It shows:

Figure 1 is a schematic view of a fuel injection valve according to an embodiment of the invention.

Fig. 2 is an enlarged section of the arrangement of the first and second control valve shown in FIG. 1; and

Fig. 3 in diagram form the interaction between the switching position of the piezo actuator, the pressure at the nozzle and the nozzle stroke.

Description of the embodiment

In the embodiment shown in Fig. 1, the valve according to the invention is used in a fuel injection system in which the injection pump and the injection nozzle form a unit (so-called pump-nozzle unit (PDE)). Such an injection system is shown in FIG. 1. The injection valve 1 consists of a decentralized pump unit, not shown, and a control unit 2 . The control unit 2 comprises a piezo actuator 3 arranged in a housing (not shown ) with a piston 4 which controls a pump control valve 6 by means of hydraulic transmission 5 .

Here, the pump control valve 6 in Fig. 1 via a spring 7 in the closed position of the pump Steuererven valve 6 is biased. The pump control valve 6 is followed in series by an injector control valve 8 in FIG. 1, which in turn is biased into the closed position by a spring 9 . Here, a gap hv is formed between the pump control valve 6 and the injector control valve 8 . Its mode of operation will be described later.

The pump control valve 6 in FIG. 1 is hydraulically connected on the one hand to the control rail 10 and on the other hand to a first control chamber 11 . A piston 12 adjoins the control chamber 11 downward in FIG. 1 and is biased into the control chamber 11 by means of a spring 13 . In addition, the piston 12 is formed with a central piston 14 which opens into a high-pressure chamber 15 . Here, the control chamber 11, together with pistons 12 , 14, act as a high-pressure pump.

The high pressure chamber 15 is formed with a well-known to run valve 16 which controls the inlet 17 of the fuel in the high pressure chamber 15 . Finally, the high-pressure chamber 15 in FIG. 1 is connected to a nozzle 18 constructed in a known form.

In addition to the connection of the control rail 10 to the pump control valve 6 , the control rail 10 is also connected to the second control chamber 19 via an inlet throttle 20 . The control chamber 19 in this case has an outlet throttle 21 which opens into the injector control valve 8 and, if this control valve 8 is in the appropriate position, enables an outflow into a leak oil channel 22 . This leakage oil channel 22 is also connected to the first control chamber 11 , wherein the connection can be interrupted by the pump control valve 6 .

In FIG. 1, two pistons 23 , 24 adjoin the control chamber 19 in the form of a hydraulic transmission with pressure chamber 25 connected between them. Between valve member 26 and piston 24 , another piston 27 is angeord net, which biases the valve member 26 into its closed position via a sealing spring 28 .

In Fig. 2, the interaction between the pump control valve 6 and injector control valve 8 is shown in an enlarged view. Here, in the respectively closed position of the two control valves 6 , 8, a gap hv is formed between these two components. Furthermore, in the area of the gap hv there is a control edge 29 , long, which can engage a slide area 30 of the pump control valve 6 , thereby interrupting the connection between the control chamber 6 and the leakage oil channel 22 .

In the present exemplary embodiment of the injection valve 1 according to the invention, a 3/2-seat slide valve is used as the pump control valve 6 and a 2/2-valve with inlet 20 and outlet throttle 21 is used as injector control valve 8 .

Mode of action

In the following, the operation of the injection valve 1 according to the invention will be described with reference to the flow charts of FIG. 3. If the piezo actuator 3 is energized, the piston 4 moves in FIG. 1 to the right and, by means of the hydraulic transmission 5, causes a shift of the control valve 6 against the spring 7 to the right until the gap hv is compensated. As a result, the control rail 10 connected to a decentralized control pump (not shown) comes into connection with the first control chamber 11 and thus acts on the control chamber 11 with the pressure specified in the control rail 10 . At the same time, the leak oil connection between the leak oil channel 22 and the first control chamber 11 is partially closed, so that a pressure builds up in the control chamber 11 . This pressure is transmitted by means of the piston 12 to the piston 14 and thus to the pressure chamber 15 . However, a ratio in the ratio of d1 / d2 takes place accordingly to the diameters of the pistons 12 and 14 . In the pressure chamber 15 , the fuel supplied by the inlet valve 16 is pressurized by means of the applied pressure from the piston 14 and fed to the nozzle 18 and the valve member 26 is pressurized with this pressure in the opening direction with respect to the injection opening.

At the same time, however, the pressure of the control rail 10 on the second control chamber 19 and by means of the hydraulic translation of the pistons 23 , 24 and 27 with a transmission ratio of d3 / d4 on the valve member 26 is brought up. Here, the gear ratios between d1 / d2 and d3 / d4 are selected such that the valve member 26 remains in its closed position. At the same time, however, the pressure transmitted from the high-pressure chamber 15 to the valve member 26 continues to increase.

If the piezo actuator 3 is now energized, the control valve 6 executes a further movement in FIG. 1 to the right, so that the connection between the first control chamber 11 and the leakage oil channel 22 is closed, as a result of which the same pressure in the first control chamber 11 as in the control rail 10 sets.

At the same time, the control valve 8 is moved to the right against the spring 9 in FIG. 1 and opens the connection between the outlet throttle 21 and leakage oil channel 22 , whereby the pressure in the second control chamber 19 decreases. Consequently, also takes the in the "right strand" of Fig. 1, acting pressure on the valve member 26 from, whereas the increases by the applied in Fig. 1, "the left strand" pressure to the valve member 26. Accordingly, the inlet opening of the nozzle 18 is opened and a pre-injection VE occurs, as can be seen from the three diagrams of FIG. 3. If the energization of the piezo actuator 3 is now reduced, the control valves 6 , 8 are moved into their intermediate position - control valve 6 - and their closed position - control valve 8 - due to the springs 7 , 9 . At the same time, pressure equalization takes place on the valve member 26 with respect to the pressures of the left leg and the right leg of FIG. 1. Accordingly, the valve member 26 is returned to its closed position so that no further injection process takes place.

If the main injection H is now to be carried out, only the piezo actuator 3 has to be energized, so that the same states of the individual components of the injection valve according to the invention as in the pre-injection VE set. With regard to the main injection and its characteristics, reference is again made to the three diagrams in FIG. 3.

In connection with the nozzle pressure / time diagram of Fig. 3 it should be noted that the pressure drop after the nozzle opening results in both the pre-injection and the main injection from the fact that the liquid can only be replenished at the speed of sound. There is therefore a drop in pressure after opening the nozzle, which is only compensated for by subsequent delivery. The pressure drop in the main injection is greater than in the pre-injection, since a larger volume of liquid is withdrawn.

The present invention can of course also be used differently designed valves with hydraulic but also mechanical translators can be used.

The previous description of the exemplary embodiment ge according to the present invention is for illustrative purposes only Purposes and not to limit the invention. As part of Various changes and modifications to the invention NEN possible to the scope of the invention as well as its equiva leave lente.

Claims (10)

1. Valve ( 1 ) for controlling liquids with a first valve element ( 6 ), which controls the pressurization of a high pressure chamber ( 15 ), with a control element ( 3 ), which controls the actuation of the first valve element ( 6 ), and with a second valve element ( 8 ), which controls the pressurization of a valve member ( 26 ), characterized in that the control element ( 3 ) is designed as a piezo actuator and additionally controls the actuation of the second valve element ( 8 ). 2. Valve for controlling liquids according to claim 1, characterized in that the first and second valve elements ( 6 , 8 ) are connected in series. 3. Valve for controlling liquids according to claim 2, characterized in that a gap (hv) is provided between the first and second Ven tilelement ( 6 , 8 ). 4. Valve for controlling liquids according to one of claims 1 to 3, characterized in that between the first valve element ( 6 ) and the high-pressure chamber ( 15 ), a first control chamber ( 11 ) is arranged, which by pressure from a control rail ( 10 ) can be acted upon. 5. Valve for controlling liquids according to claim 4, characterized in that the first control chamber ( 11 ) can perform a pressure ratio from the control rail ( 10 ) to the high-pressure chamber ( 15 ). 6. Valve for controlling liquids according to claim 4 or 5, characterized in that the first control chamber ( 11 ) with egg nem through the valve element ( 6 ) to be opened or closable drain oil channel ( 22 ) is connected. 7. Valve for controlling liquids according to one of claims 1 to 6, characterized in that between the second valve element ( 8 ) and valve member ( 26 ) a second control chamber ( 19 ) is arranged, which is acted upon by pressure from the control rail ( 10 ) . 8. Valve for controlling liquids according to claim 6, characterized in that the second control chamber ( 19 ) is connected to an outlet throttle ( 21 ) which is opened or closed by the second valve element ( 8 ). 9. Valve for controlling liquids according to one of claims 4 to 8, characterized in that the control rail ( 10 ) is connected to a decentralized control pressure pump. 10. Valve for controlling liquids according to one of claims 4 to 9, characterized in that the first control chamber ( 11 ) and / or the second control chamber ( 19 ) is / are designed as hy draulic translator.