EP1317618A1

EP1317618A1 - Valve for controlling liquids

Info

Publication number: EP1317618A1
Application number: EP01951348A
Authority: EP
Inventors: Friedrich Boecking
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2000-09-08
Filing date: 2001-05-25
Publication date: 2003-06-11
Also published as: KR20020061614A; JP2004508493A; DE10044389A1; US20030038259A1; WO2002020975A1; CZ20021538A3

Abstract

The invention relates to a valve for controlling liquids. Said valve comprises a piezoactuator (2), a transmission element (3) that transmits the stroke of the piezoactuator (2), a return element (4) and a valve element (5). The transmission element is configured as a tumbler (3) and the valve element (5) is integrated into said tumbler, thereby achieving a high system rigidity at a reduced number of components.

Description

Valve for controlling liquids

State of the art

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

Valves for controlling liquids are known in different configurations. For example, a piezoelectric fuel injection valve is known from US Pat. No. 4,022,166, in which the valve member is controlled via a piezoelectric element. The stroke of the piezoelectric element is transmitted directly to the valve needle via a lever. Furthermore, two return springs are provided in order to hold the valve needle and the lever in their initial position. Because of this configuration with two return springs, which are connected to one another via the lever, a very vibration-sensitive structure is created, which is particularly unsuitable for high-pressure injection, since the vibrations can build up.

Furthermore, injectors are known which use hydraulic translators to translate the stroke of a piezo actuator. However, such solutions generally have one relatively complicated structure and consist of a large number of parts. Since the piezo actuators only have a very small lifting capacity, the effort involved in the known mechanical or hydraulic translators is relatively great.

Advantages of the invention

The valve according to the invention for controlling liquids with the features of claim 1 has the advantage that it is very simple and can be manufactured inexpensively. Due to the design of the translator as a rocker arm and the integration of the valve element in the rocker arm, the valve according to the invention for controlling liquids has only a small number of components. A particularly compact design of the valve according to the invention is thus achieved. This provides maximum system rigidity from the actuator to the valve seat, with a minimum number of contact areas between the individual components being obtained. Furthermore, possible stroke tolerances of the system can be compensated for via the translation. Since the booster is arranged in a fuel-filled space in the valve, good lubrication is provided, which results in less wear.

According to a preferred embodiment of the present invention, the rocker arm and the valve element are formed in one piece. In other words, the valve element is integrated directly in the rocker arm. As a result, the number of individual components can be minimized, since no separate valve element is necessary. The geometric shape of the area of the rocker arm, which serves as a valve element, can be arbitrary. It is only important to note that there is sufficient sealing properties on the valve seat. they are. For example, the area of the rocker arm serving as a valve element can be hemispherical or conical.

According to another preferred embodiment of the present invention, the valve element is designed as a separate ball which can be actuated via the rocker arm.

A recess is preferably formed in the rocker arm to accommodate the valve element. The recess can either be designed in such a way that the valve element is fixed in the recess (e.g. by means of an interference fit) or in such a way that the valve element is arranged loosely in the recess. When the valve element is arranged loosely in the cutout, it must of course be ensured that the travel of the rocker arm is limited when the valve is opened, so that the loose valve element cannot be lost.

The restoring element preferably engages directly on

Rocker arm. A spring such as e.g. used a coil spring. A spring seat is particularly preferably formed in the rocker arm. This can be formed, for example, by a recess arranged in the rocker arm, which receives one end of the spring.

So that the translator designed as a rocker arm has as little scope as possible, the translator is preferably arranged in a guide sleeve. The translator is then guided in this guide sleeve during operation. Here, the guide sleeve can be easily manufactured in advance with very low component tolerances. Thus the transfer only minimal play, which gives the entire system maximum rigidity.

According to another preferred embodiment of the present invention, the valve element is designed as a double-seat valve. The two seats are preferably arranged on a lever side of the rocker arm. The valve can be designed in such a way that it can assume three positions, namely a first position in which the valve element lies against and closes the first valve seat, a second position in which the valve element lies against and closes the second valve seat. and a third position in which the valve element is not in contact with either of the two valve seats, so that both valve seats are open (middle position).

The rocker arm is preferably connected to the piezo actuator via a drawstring. This enables the valve to be easily held in the central position.

In order to easily integrate the valve element in the rocker arm in a double-seat valve, a through opening is preferably formed in the rocker arm, in which a separate valve element, such as e.g. a ball is picked up.

The valve according to the invention is preferably used to control liquids in an injection device for a co-mon-rail system. It is particularly preferably used as a control valve of an injector.

According to the invention, a valve for controlling liquids is thus provided which, due to its small number of components, provides a compact design and thus maximum system rigidity. This allows the The injection process, in particular in the case of fuel injection in storage injection systems, can be carried out more precisely and further improved.

drawings

Several embodiments of the invention are explained in more detail in the following description. Show it:

Figure 1 is a schematic partial sectional view of a

Control valve for a fuel injection valve according to a first embodiment of the present invention;

FIG. 2 shows a schematic partial sectional view of a control valve for a fuel injection valve according to a second exemplary embodiment of the present invention;

FIG. 3 shows a schematic partial sectional view of a control valve for a fuel injection valve according to a third exemplary embodiment of the present invention;

FIG. 4 shows a schematic partial cross-sectional view of a control valve for a fuel injection valve according to a fourth exemplary embodiment of the present invention;

Figure 5 is a graphical representation of the nozzle position of the fuel injection valve as a function of the control valve and

Figure 6 is a graphical representation of the position of the control valve shown in Figure 4 over time.

Description of the embodiments Figure 1 shows a control valve for a fuel injector in a Comrrton rail system. As shown in FIG. 1, the control valve 1 comprises a piezo actuator 2, a mechanical translator designed as a rocker arm 3 and a helical spring 4 used as a reset element. The rocker arm is arranged in a space 25 in the valve.

As shown in FIG. 1, the rocker arm 3 has a hemispherical area 5 which is designed as a valve element. The hemispherical region 5 closes a valve seat 6. Furthermore, the rocker arm 3 is rotatably mounted at two points, namely a first bearing 9 and a second bearing 10. The rocker arm 3 rotates about an imaginary point P, which lies in the middle of the distance between the two bearing points 9 and 10. Furthermore, the rocker arm 3 has a support surface 13 on which a piston 8 rests, which is connected to the piezo actuator 2. The area 5 of the rocker arm 3 closes an outlet from a control chamber 18, in which a control piston 19 is arranged. The control piston 19 is indirectly or directly connected to a valve needle of the fuel injection valve in order to open or close it. A fuel supply line 17 is connected to the control chamber 18 via a throttle 16.

Since the piezo actuator 2 only has a very small stroke, this stroke is transmitted to the rocker arm 3 via the piston 8. The ratio of the rocker arm is a: b, where a is the length of the lever arm between a straight line AA through the bearing points 9 and 10 and a center line BB for a bore to the control chamber 18, which is closed or closed by the area 5 of the rocker arm 3. is opened. The length b is the distance between the axis AA and an axis CC, which forms the center line of the piston 8, which presses the rocker arm 3.

The function of the control valve according to the first embodiment is described below. If fuel which is in contact with an injection needle of the injector under high pressure via the supply line 17 is to be injected, the piezo actuator 2 is activated such that it carries out a stroke in the direction of the piston. This stroke of the piezo actuator 2 is transmitted via the piston 8 to the first lever b of the rocker arm 3. As a result, the rocker arm 3 rotates about the point P on the axis A-A, so that the region 5 of the rocker arm is lifted off the valve seat 6 against the force of the coil spring 4. As a result, the control chamber 18 is connected via a throttle 15 to the chamber 25 in which the rocker arm is arranged. Control chamber 18 is also connected to fuel supply line 17 via throttle 16. If the control valve is now in the open state, fuel flows into the space 25 via the throttle 15. As a result, the pressure in the area of the control space 18 drops, as a result of which the control piston 19 is moved in the direction of the rocker arm 3. As a result, the valve needle of the injector lifts off its seat, so that fuel is injected into a combustion chamber.

When the piezo actuator 2 is deactivated, the rocker arm 3 returns to its starting position via the return spring 4, so that the area 5 of the rocker arm 3 is again in contact with the valve seat 6. As a result, the pressure in the area of the control chamber 18 rises, as a result of which the control piston 19 is moved in the opposite direction. As a result, the valve needle seals the seat of the injector again and the fuel injection is ended. The integral design of the rocker arm with the area 5, which opens and closes as a valve element on the valve seat 6, results in a very compact design with few components. Furthermore, the control valve can thereby be provided as a very rigid system, so that in particular the injection accuracy can be improved in comparison with the prior art.

FIG. 2 shows a second exemplary embodiment of a control valve for an injector for injecting fuel. The same or functionally the same parts are denoted by the same reference numerals as in the first embodiment. Since the second exemplary embodiment essentially corresponds to the first exemplary embodiment, only differences are explained in detail below.

In contrast to the first exemplary embodiment, the rocker arm 3 of the second exemplary embodiment is designed such that it has a cutout 11 in which a separate valve element 5 is arranged. As shown in FIG. 2, the valve element is designed as a valve ball 5. The valve ball 5 is loosely arranged in the recess 11 of the rocker arm 3.

As further shown in Figure 2, the rocker arm 3 is only stored at a bearing 9. Thus, the pivot point of the rocker arm 9 is at the contact area of the bearing 9 with the rocker arm 3 on the line A-A.

In order to increase the rigidity of the system, two protruding bulges 23 and 24 are formed on the side walls of the space 25 for receiving the rocker arm, between which the rocker arm 3 is arranged. These curvatures 23 and 24 serve to guide the rocker arm 3 and further increase the rigidity. system. The lever ratio of the rocker arm 3 is determined by the length of the two arms a: b and can be changed depending on the application by changing the lever arm lengths. To do this, another rocker arm element 3 must simply be installed in the injector, the bearing point 9 of which is shifted to the left or right.

The function of the injector shown in FIG. 2 essentially corresponds to the function of the injector of the first exemplary embodiment, so that reference can be made to the description in the first exemplary embodiment.

FIG. 3 shows a control valve for an injector for injecting fuel in accordance with a third exemplary embodiment of the present invention. The same or functionally identical parts are identified by the same reference numerals as in the two previously described exemplary embodiments. Since the third exemplary embodiment essentially corresponds to the second exemplary embodiment, only differences are explained in detail below.

In contrast to the second exemplary embodiment, no curvatures 23 and 24 are provided in the third exemplary embodiment. Instead, a guide sleeve 20 is provided in the third exemplary embodiment in order to guide the rocker arm 3.

Since the guide sleeve 20 can be easily manufactured in advance and can meet high tolerance requirements, the rigidity of the system can be further improved. Otherwise, the third exemplary embodiment corresponds to the second exemplary embodiment, so that a further description is not necessary.

FIG. 4 shows a valve for controlling liquids in accordance with a fourth exemplary embodiment of the present invention. shown. Identical or functionally identical parts are identified by the same reference symbols as in the exemplary embodiments described above.

The fourth embodiment of the present invention is designed as a double seat valve. A first valve seat 6 and a second valve seat 7 are provided, which can each be opened or closed via a common valve element 5.

As shown in Figure 4, the rocker arm 3 of the valve is designed such that it has a through opening 14. In this through opening 14, a valve element 5 designed as a ball is fixed e.g. secured with a press fit. The rocker arm 3 is rotatably mounted on a first bearing 9. A helical spring 4 is again provided as a resetting device, which acts on the rocker arm 3 via a piston 22. As shown in Figure 4, the spring 4 is arranged such that it lies on a common axis C-C with a piston 8, via which the stroke of the

Piezo actuator 2 is transferred to the rocker arm 3. As in the previous examples, the leverage ratio is again a: b.

Furthermore, two protruding curvatures 23 and 24 are arranged in the housing, which serve to guide the rocker arm 3.

In the closed state, the valve on seat 6 is closed. When the piezo actuator 2 is actuated, the valve is moved against the force of the spring 4 via the rocker arm 3 from the valve seat 6 to the valve seat 7, so that the valve seat 7 is closed. By pulling the piezo actuator 2 by means of a biasing spring (not shown), the rocker arm 3 is pulled over a tension band 9, which is firmly connected to the piston 8 and surrounds the right lever arm of the rocker arm 3 in a U-shape, again lifted off the seat 7, so that a continuous opening from a line 26 to a control chamber 18 is present. As a result, a fluid can flow from the control chamber 18 to the line 26, so that a negative pressure arises in the control chamber 18 and the control piston 19 moves in the direction of the valve ball 5 and, for example, a valve needle connected to the control piston 19 is lifted from its seat by one Allow fuel injection. The valve 1 is reset via the spring 4, so that the ball 5 rests against the seat 6.

FIGS. 5 and 6 show the stroke of the control valve 1 (FIG. 6) or the stroke of the injection valve (FIG. 5) over time. As shown in FIG. 6, the seat 6 is closed in the initial state of the valve 1. If the piezo actuator 2 is now activated, the valve 1 closes briefly on the seat 7, a central position between the seat 6 and the seat 7 then being assumed due to the above-mentioned reset of the piezo actuator, in which a vacuum acts on the control piston 19. As a result of this negative pressure, the needle valve of the injection valve opens during the central position of the control valve, as shown in FIG. 5, in order to inject fuel into a combustion chamber. After deactivating the piezo actuator 2, this takes

Control valve again its basic position on the valve seat 6, which also stops the injection of fuel (see FIGS. 5 and 6).

FIG. 5 shows a small needle stroke before the actual injection, which theoretically occurs in the meantime between the opening of the valve seat 6 and the closing of the valve seat 7. However, due to the inertia of the system, this is of no importance in practice, especially since the switching times of the control valve are very short.

Thus, the present invention relates to a valve for controlling liquids. The valve comprises a piezo actuator 2, a translator 3, which translates a stroke of the piezo actuator 2, a resetting element 4 and a valve element 5. The translator is designed as a rocker arm 3 and the valve element 5 is integrated in the rocker arm, which means a high level System rigidity is achieved with a minimized number of parts.

The preceding description of the exemplary embodiments according to the present invention is only for illustrative purposes and not for the purpose of restricting the invention. Various changes and modifications are possible within the scope of the invention without leaving the scope of the invention and its equivalents.

Claims

Expectations

1. Valve for controlling liquids with a piezo actuator (2), a translator for translating a stroke of the piezo actuator (2), a reset element (4) and a valve element (5), characterized in that the translator as a rocker arm (3 ) is formed and the valve element (5) is integrated in the rocker arm (3).

2. Valve for controlling liquids according to claim 1, characterized in that the rocker arm (3) and the valve element (5) are integrally formed.

3. Valve for controlling liquids according to claim 1, characterized in that the valve element (5) is designed as a ball.

4. Valve for controlling liquids according to one of claims 1 to 3, characterized in that the rocker arm (3) has a recess (11) to receive the valve element (5).

5. Valve for controlling liquids according to one of claims 1 to 4, characterized in that the return element (4) acts directly on the rocker arm (3).

6. Valve for controlling liquids according to one of claims 1 to 5, characterized in that the translator is arranged in a guide sleeve (20).

7. Valve for controlling liquids according to one of claims 1 to 6, characterized in that the valve element (5) is designed as a double-seat valve.

8. Valve for controlling liquids according to claim 7, characterized in that the rocker arm (3) via a tension band (21) is connected to the piezo actuator (2).

9. Valve for controlling liquids according to claim 7 or 8, characterized in that a through opening (14) is formed in the rocker arm (3), in which a separate valve element (5) is received.

10. Use of a valve for controlling liquids according to one of claims 1 to 9 in an injection device for a common rail system.