EP2055927B1

EP2055927B1 - Actuator arrangement and injection valve

Info

Publication number: EP2055927B1
Application number: EP20070021324
Authority: EP
Inventors: Enio Biasci; Edoardo Giorgetti; Claudio Malasoma
Original assignee: Continental Automotive GmbH
Current assignee: Continental Automotive GmbH
Priority date: 2007-10-31
Filing date: 2007-10-31
Publication date: 2010-05-26
Anticipated expiration: 2027-10-31
Also published as: EP2055927A1; DE602007006816D1

Description

The invention relates to an actuator arrangement and injection valve.
Actuator arrangements are in wide spread use, in particular injection valves for instance for internal combustion engines comprise actuator arrangements, which comprise solid state actuator units. In order to inject fuel, the solid state actuator unit is energized so that a fluid flow through the fluid outlet portion of the injection valve is enabled.
In order to enhance the combustion process in view of the creation of unwanted emissions, the respective injection valve may be suited to dose fluids under very high pressures. The pressures may be in case of a gasoline engine, for example in a range of up to 200 * 10⁵ kg/(m*s²) or in the case of diesel engines in a range of up to 2,000 * 10⁵ kg/(m*s²). In order to enable fast response times electric energy needs to be transmitted to or from the actuator arrangement in a very fast way.
US 6,814,314 B discloses a fuel injection valve, which comprises a piezoelectric or magnetostrictive actuator. To compensate for temperature expansion, at least one damping element made of a solid is present and exhibits an almost static behavior at a high deformation rate and is elastically or plastically deformable at a low deformation rate.
US 4,725,002 A discloses a metering valve with a piezoelectric control member. The metering valve comprises a damping piston connected axially to the piezoelectric control member to compensate slow changes in the length of the piezoelectric control member. A valve housing defines with the end face of the piston a damping chamber, which is filled with a damping liquid.
WO 02/40858 A discloses an injector housing with an actuator comprising a head plate. A first damping disc is arranged between the head plate of the actuator and a housing body. Means for exerting a force are arranged in the housing body, by means of which the actuator is pressed against the first damping disc.
The object of the invention is to create an actuator arrangement that is simply to be manufactured and which enables reliable operation.
This object is achieved by the features of the independent claims. Advantageous embodiments of the invention are given in the sub-claims.
According to a first aspect the invention is distinguished by an actuator arrangement, comprising a housing body with a recess, and a solid state actuator unit within the recess with a longitudinal axis comprising electric pins being electrically coupable to a power supply. The solid state actuator unit comprises a first axial end area designed to act as drive side and a second axial end area facing a free volume of the recess, wherein the free volume is filled at least in part with a damping body and the damping body comprises micro plastic balls.
This has the advantage that undesired movements of the solid state actuator unit can be prevented and vibrations within the actuator arrangement can be limited due to the fact that the damping body is designed to dampen movements of the solid state actuator unit in the second axial end area. Thus, the damping of the actuator arrangement can be carried out especially reliable. In particular, electric connections and resistance weldings between the electric pins of the solid state actuator unit and the power supply can be protected against undesired movements and vibrations. Moreover, the damping body within the actuator arrangement is simply to be manufactured. In addition, the micro plastic balls can be applied in a simple manner, can be processed fast and in that way contribute to a low production time for the actuator arrangement. The damping body may comprise liquid, solid state or gel, wherein the gel corresponds to a visco-elastic fluid.
In an advantageous embodiment of the invention the damping body comprises a silicon based filler. By this, the damping of the actuator arrangement can be carried out especially reliable. Since the silicon is not liquid but viscid after drying, an additional separation from the damping body to the rest of the free volume may be omitted.
In a further advantageous embodiment of the invention the damping body comprises a foam. This has the advantage that the damping of the actuator arrangement is especially reliable, whereas the foam can be processed fast and in that way contributes to a low production time for the actuator arrangement.
In a further advantageous embodiment the damping body comprises micro rubber balls. By this, the damping of the actuator arrangement can be carried out especially reliable. Also the micro rubber balls can be applied in a simple manner, can be processed fast and in that way contribute to a low production time for the actuator arrangement.
In a further advantageous embodiment the damping body comprises a channel being designed to penetrate and provide a fluid communication between the free volume and at least a part of the surface of the solid state actuator unit. This has the advantage that the channel as a simple element allows a continuous oxygen flow within the actuator arrangement. In particular it provides an oxygen flow advantageous for ceramic and therefore, prevents breaking of the ceramic.
According to a second aspect the invention is distinguished by an injection valve with a valve assembly within a recess and an actuator arrangement of the first aspect of the invention, comprising a solid state actuator unit within the recess, wherein the solid state actuator unit is being designed for acting on the valve assembly.
Exemplary embodiments of the invention are explained in the following with the help of schematic drawings. These are as follows:

Figure 1,: an actuator arrangement,
Figure 2,: a specific actuator arrangement in an injection valve.

Elements of the same design and function that appear in different illustrations are identified by the same reference characters.
Figure 1 shows an actuator arrangement 10 comprising a housing body 12 with a recess 14, and a solid state actuator unit 16 within the recess 14 of the housing body 12 with a longitudinal axis A comprising electric pins 18 being electrically coupable to a power supply. For example, the electric pins 18 might be coupled by weldings, in particular resistance weldings, or soldered connections to an electric conductor 70 (figure 2), which is supplied with electric energy. In particular, injection valves for instance for internal combustion engines may comprise the actuator arrangement.
The solid state actuator unit 16 comprises a solid state actuator 20. The solid state actuator 20 changes its length in axial direction depending on a control signal applied to it such as electric energy supplied to it. The solid state actuator unit 16 is typically a piezo actuator unit. It may however also be any other solid state actuator unit known to the person skilled in the art such as a magnetostrictive actuator unit.
The solid state actuator unit 16 comprises a first axial end area 22 designed to act as drive side and a second axial end area 24, which is facing away from the first axial end area 22, facing a free volume 26 of the recess 14, in particular directly facing it. The electric pins 18 can be arranged in optional direction, for instance in axial direction of the solid state actuator unit 16 or perpendicular to it. In particular, the electric pins 18 protrude in the free volume 26. On the drive side of the solid state actuator unit 16 facing the first axial end area 22 optional actuating elements are arranged such as a valve needle or a rotor.
An actuator housing enclosing the solid state actuator 20 may comprise a spring tube 28, a top cap 30 and a bottom cap 31. Part of the top cap 30 may form at least part of the second axial end area 24. Part of the bottom cap 31 may form at least part of the first axial end area 22 comprising the drive side of the solid state actuator unit 16. The solid state actuator unit 16 further comprises a piston 32, which is coupled to the top cap 30 or may in one peace form part of the top cap 30. It may apply an axial preload force on the solid state actuator unit 16.
The energizing of the solid state actuator unit 16 may cause undesired movements and vibrations within the actuator arrangement 10, which for example might stress weldings. By filling the free volume 26 at least in part with a damping body 34 with the damping body 34 beeing mechanically coupled to the second axial end area 24 of the solid state actuator unit 16, undesired movements of the solid state actuator unit 16 can be prevented and vibrations within the second axial end area 24 of the actuator arrangement 10 can be limited. In particular, electric connections and resistance weldings between the electric pins 18 of the solid state actuator unit 16 and the power supply can be protected against undesired movements and vibrations. The damping body 34 comprises micro plastic balls such as micro rubber balls or combinations of the same with a silicon based filler or a foam.
Therefore, some kind of elasticity for damping is provided. And by this, the damping body 34 within the actuator arrangement 10 is simply to be manufactured. In the case of the silicon based filler or the foam, there has to be no additional separation from the damping body 34 to the rest of the free volume 26, since none of them is fluid. By using the micro plastic balls, especially the micro rubber balls, an additional limitative element such as a spring rest may be advantageous. Typically, the micro plastic balls show dimensions of a radius in a range of 0.3 mm up to 1.0 mm, whereas an especially advantageous radius is 0.5 mm.
The damping body 34 may comprise a channel 36 being designed to penetrate and provide a fluid communication between the free volume 26 and at least a part of the surface of the solid state actuator unit 16. For instance, the channel 36 may provide fluid communication between at least a part of the shell of the solid state actuator unit 16 and the free volume 26. Therefore, the channel 36 as a simple element allows a continuous oxygen flow within the actuator arrangement 10. In particular, it prevents breaking of the ceramic by providing an oxygen flow advantageous for ceramic.
Figure 2 shows an injection valve 38 that may be used as a fuel injection valve for an internal combustion engine. The injection valve 38 comprises a valve assembly 40, the solid state actuator unit 16 and a connector 42.
The injection valve 38 has a two- part housing body 44, 46 with a tubular shape which has the central longitudinal axis

A. The housing body 44, 46 of the injection valve 38 comprises the recess 14 which is axially led through the housing body 44, 46.

The valve assembly 40 comprises a valve body 48 and a valve needle 50. The valve body 48 has a valve body spring rest 52 and the valve needle 50 comprises a valve needle spring rest 54, both spring rests 52, 54 supporting a spring 56 arranged between the valve body 48 and the valve needle 50. Between the valve needle 50 and the valve body 48 a bellow 58 is arranged which is sealingly coupling the valve body 48 with the valve needle 50. By this a fluid flow between the recess 14 and a chamber 60 is prevented. Furthermore, the bellow 58 is formed and arranged in a way that the valve needle 50 is actuable by the solid state actuator unit 16.
A fluid outlet portion 62 is closed or open depending on the axial position of a valve needle 50. By changing its length, the solid state actuator 20 can exert a force to the valve needle 50. The force from the solid state actuator 20 being exerted to the valve needle 50 in an axial direction allows or prevents a fluid flow through the fluid outlet portion 62. Furthermore, the injection valve 38 has a fluid inlet portion 64 which is arranged in the housing body 44, 46 and which for instance is coupled to a not shown fuel connector. In this example, the fuel connector is designed to be connected to a high pressure fuel chamber of an internal combustion engine, the fuel is stored under high pressure, for example, under the pressure above 200 · 10⁵ Pa (200 bar).
The valve assembly 40 is arranged in the injection valve 38 facing the first axial end area 22 on the drive side of the solid state actuator unit 16 sharing a part of the recess 14 of the housing body 44 of the actuator arrangement 10 along the longitudinal axis A.
A thermal compensator unit 66 is arranged facing the second axial end area 24 of the solid state actuator unit 16 and facing the free volume 26 and is mechanically coupled to the piston 32 of the solid state actuator 20. The thermal compensator unit 66 enables to set an axial preload force on the solid state actuator unit 16 via the piston 32 to compensate changes of the fluid flow through the fluid outlet portion 62 in the case of temperature changes of the injection valve 38.
The injection valve 38 further comprises the connector 42 with a non-conductive connector body 68 in which an electric conductor 70 is arranged. Electric energy can be supplied to the electric conductor 70 of the connector 42. Furthermore, the solid state actuator unit 16 comprises an adapter 72 consisting of terminal elements 74. The electric conductor 70 of the connector 42 is electrically coupled to one of the terminal elements 74 of the adapter 72 which is electrically coupled to another of the terminal elements 74 which on its part is electrically coupled to the electric pins 18 of the solid state actuator 20. Consequently, electric energy can be simply supplied to the solid state actuator 20 via the connector 42.
The damping body 34, which is filled at least into a part of the free volume 26, may be conterminous to limitative elements facing the second axial end area 24 of the solid state actuator unit 16. For example, the limitative element may be a spring rest of the thermal compensator unit 66. In this case, especially reliable damping of undesired movements of the solid state actuator unit 16 and vibrations within the second axial end area 24 of the actuator arrangement 10 is accomplished.
In the following, the function of the injection valve 38 will be described in detail:

The fluid is led from the fluid inlet portion 64 through the housing body 44, 46 to the fluid outlet portion 62.

The valve needle 50 prevents a fluid flow through the fluid outlet portion 62 in the valve body 48 in a closing position of the valve needle 50. Outside of the closing position of the valve needle 50, the valve needle 50 enables the fluid flow through the fluid outlet portion 62.
The solid state actuator 20 may change its axial length if it is energized. By changing its length the solid state actuator 20 may exert a force on the valve needle 50. The valve needle 50 is able to move in axial direction out of the closing position. Outside the closing position of the valve needle 50 there is a gap between the valve body 48 and the valve needle 50 at the first axial end area 22 of the injection valve 38 facing away from the solid state actuator 20. The spring 56 can force the valve needle 50 via the valve needle spring rest 54 towards the solid state actuator 20. In the case the solid state actuator 20 is de-energized, the solid state actuator 20 shortens its length. The spring 56 can force the valve needle 50 to move in axial direction in its closing position. It is depending on the force balance between the force on the valve needle 50 caused by the solid state actuator 20 and the force on the valve needle 50 caused by the spring 56 whether the valve needle 50 is in its closing position or not.
If the solid state actuator 20 is energized, undesired movements and vibrations can occur at the top cap 30 of the actuator housing. A rigidly coupling of the adapter 72 to the top cap 30 let the forces caused by the vibrations be transmitted directly from the top cap 30 of the actuator housing to the adapter 72. Thus, for example electric connections between the electric pins 18 of the solid state actuator unit 16 and the power supply may be stressed. By filling the free volume 26 at least in part with a damping body 34, undesired movements of the solid state actuator unit 16 can be prevented and vibrations within the second axial end area 24 of the actuator arrangement 10 can be limited, which enables reliable operation.

Claims

Actuator arrangement (10), comprising
- a housing body (12) with a recess (14), and

- a solid state actuator unit (16) within the recess (14) with a longitudinal axis (A) comprising electric pins (18) being electrically coupable to a power supply, wherein the solid state actuator unit (16) comprises a first axial end area (22) designed to act as drive side and a second axial end area (24) facing a free volume (26) of the recess (14), wherein the free volume (26) is filled at least in part with a damping body (34), characterized in that
the damping body (34) comprises micro plastic balls.
Actuator arrangement according to claim 1, wherein the damping body (34) comprises a silicon based filler.
Actuator arrangement according to one of the preceding claims, wherein the damping body (34) comprises a foam.
Actuator arrangement according to claim 1, wherein the micro plastic balls are micro rubber balls.
Actuator arrangement according to one of the preceding claims, wherein the damping body (34) comprises a channel (36) being designed to penetrate and provide a fluid communication between the free volume (26) and at least a part of the surface of the solid state actuator unit (16).
Injection valve (38) with a valve assembly (40) within a recess (14) and an actuator arrangement (10) according to one of the preceding claims, comprising a solid state actuator unit (16) within the recess (14), wherein the solid state actuator unit (16) is designed for acting on the valve assembly (40).