EP2078846B1

EP2078846B1 - Actuator arrangement and injection valve

Info

Publication number: EP2078846B1
Application number: EP20080000568
Authority: EP
Inventors: Cristiano Zanoboni
Original assignee: Continental Automotive GmbH
Current assignee: Continental Automotive GmbH
Priority date: 2008-01-14
Filing date: 2008-01-14
Publication date: 2014-12-03
Anticipated expiration: 2028-01-14
Also published as: EP2078846A1

Description

The invention relates to an actuator arrangement and an 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. To enable fast response times electric energy needs to be transmitted to or from the actuator arrangement in a very fast way.
DE 10310499 A1 discloses an injection valve with an actuator, which is coupled to a valve needle for opening and closing an orifice of the injection valve. The injection valve comprises a hydraulic coupler for compensating variation in the length of the actuator due to thermal or mechanical stress.
WO 03/089781 A1 discloses an injection valve with an actuator, which is connected on one side to a valve needle and on the opposite side to a hydraulic piston of a hydraulic length compensator. A working chamber is divided by a tight separating membrane, by which a pressure can be transmitted to a hydraulic fluid by means of a dosing fluid.
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 solid state actuator unit with a longitudinal axis comprising a solid state actuator, a connecting element for connecting the solid state actuator to a compensator unit, electric pins being electrically coupable to a power supply, and a supporting element being designed and arranged to at least partly take in the connecting element and the electric pins. The solid state actuator unit comprises a first axial end area designed to act as drive side and a second axial end area facing away from the first axial end area. The actuator arrangement comprises the compensator unit being arranged facing the second axial end area of the solid state actuator unit along the longitudinal axis of the solid state actuator unit and being in contact with the solid state actuator unit via the connecting element.
This has the advantage that in a simple way the two components, the connecting element and the supporting element, instead of one component as used in general are simply to be manufactured. They may be made of different materials and/or properties. For example, for the supporting element a material can be chosen, which is easy to be welded. Furthermore, the manufacturing of the connecting element and the supporting element can be simplified compared to the case of one component, which may need to be partially hardened. This has the advantage of low production costs.
In an advantageous embodiment the connecting element is fully hardened.
This contributes to the transmission of an axial force of the compensator unit to the solid state actuator without deformation of the connecting element. In particular, the supporting element does not need to comprise a material that can be hardened. Therefore, especially reliable operation of the actuator arrangement may be enabled.
In a further advantageous embodiment the connecting element comprises stainless steel.
This has the advantage that oxidation problems may be reduced, if the connecting element comprises stainless steel.
Therefore, especially reliable operation of the actuator arrangement may be enabled.
In a further advantageous embodiment the supporting element comprises stainless steel.
The supporting element does not need to comprise a material that can be hardened. Thus, a material may be chosen, which is easy to be welded. Therefore, the supporting element may allow the passage of the electric pins and may be easily welded. The supporting element may for example comprise any standard stainless steel. This has the advantage that oxidation problems may be reduced. Therefore, especially reliable operation of the actuator arrangement may be enabled.
In a further advantageous embodiment the supporting element comprises stainless steel, which comprises around 0.05% carbon, 18% chromium and 10% nickel and in particular 0.05% carbon, 18% chromium and 10% nickel.
By this, oxidation problems may be reduced in an especially reliable way. Therefore, especially reliable operation of the actuator arrangement may be enabled.
According to a second aspect the invention is distinguished by an injection valve with a valve assembly within a recess of a housing body 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 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 solid state actuator unit 12 and a compensator unit 14.
The solid state actuator unit 12 has a longitudinal axis A and comprises a solid state actuator 16, a connecting element 18 for connecting the solid state actuator 16 to the compensator unit 14, electric pins 20 being electrically coupable to a power supply, and a supporting element 22 being designed and arranged to at least partly take in the connecting element 18 and the electric pins 20.
For example, the electric pins 20 might be coupled by weldings, in particular resistance weldings, or soldered connections to an electric conductor 64 (figure 2), which is supplied with electric energy. In particular, injection valves for instance for internal combustion engines may comprise the actuator arrangement 10.
The solid state actuator 16 changes its length in axial direction depending on a control signal applied to it such that electric energy supplied to it or is taken away from it. The solid state actuator unit 12 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 12 comprises a first axial end area 24 designed to act as drive side and a second axial end area 26 facing away from the first axial end area 24, in particular facing the compensator unit 14. On the drive side of the solid state actuator unit 12 facing the first axial end area 24 optional actuating elements are arranged such as a valve needle or a rotor.
The compensator unit 14 is arranged facing the second axial end area 26 of the solid state actuator unit 12 along the longitudinal axis A of the solid state actuator unit 12 and is mechanically coupled to the connecting element 18 of the solid state actuator unit 12. The compensator unit 14 enables to set an axial preload force on the solid state actuator unit 12 via the connecting element 18 of the solid state actuator unit 12. In particular, the compensator unit 14 is a thermal compensator unit, which is enabled to compensate temperature changes.
The connecting element 18 of the solid state actuator unit 12 is arranged along the longitudinal axis A of the solid state actuator unit 12. In particular, the connecting element 18 is getting locked within the supporting element 22 and the solid state actuator 16. The supporting element 22 is designed and arranged to at least partly take in the connecting element 18 and the electric pins 20 facing the second axial end area 26 of the solid state actuator unit 12. In particular, the electric pins 20 protrude in the supporting element 22. In particular, the connecting element 18 protrudes in the supporting element 22.
Since the solid state actuator unit 12 comprises two components, the connecting element 18 and the supporting element 22, instead of one component as used in general, the connecting element 18 and the supporting element 22 can be made of different materials and/or properties. Furthermore, the manufacturing of the connecting element 18 and the supporting element 22 can be simplified compared to the case of one component, which needs to be partially hardened. This has the advantage of low production costs. In particular, the connecting element 18 can be fully hardened. Thus, the connecting element 18 may allow the transmission of an axial force of the compensator unit 14 to the solid state actuator 16 without deformation. For the supporting element 22 a material can be chosen, which is easy to be welded. Therefore, the supporting element 22 may allow the passage of the electric pins 20 and may be easily welded. In particular, the supporting element does not need to comprise a material that can be hardened.
For example, if the supporting element 22 comprises any standard stainless steel and/or the connecting element 18 comprises stainless steel, corrosion problems may be reduced in a simple way. For example, the supporting element 22 may comprise about 0.05% carbon, 18% chromium and 10% nickel, which corresponds to X5CrNi18-10 (EN-standard) and is registered at the American Iron and Steel Institute (AISI) as AISI 304. By this, oxidation problems may be reduced in an especially reliable way. Thus, reliable operation of the actuator arrangement may be enhanced. In particular, electric connections and resistance weldings between the supporting element 22, the electric pins 20 of the solid state actuator unit 12 and the power supply can be protected against problems resulting from corrosion.
Figure 2 shows an injection valve 28 that may be used as a fuel injection valve for an internal combustion engine. The injection valve 28 comprises a valve assembly 30, the actuator arrangement 10 and a connector 32. The actuator arrangement 10 comprises the solid state actuator unit 12 and the compensator unit 14.
The injection valve 28 has a two- part housing body 34, 36 with a tubular shape with the central longitudinal axis A. The housing body 34, 36 of the injection valve 28 comprises a recess 38 which is axially led through the housing body 34, 36.
The solid state actuator unit 12 is arranged within the recess 38 of the housing body 34, 36 and comprises the electric pins 20 being electrically coupable to a power supply.
An actuator housing enclosing the solid state actuator 16 of the solid state actuator unit 12 may comprise a spring tube 40 and a cap 42. Part of the cap 42 may form at least part of the first axial end area 24 comprising the drive side of the solid state actuator unit 12. The solid state actuator unit 12 further comprises the connecting element 18 and the supporting element 22. The connecting element 18 may apply an axial preload force on the solid state actuator unit 12.
The valve assembly 30 comprises a valve body 44 and a valve needle 46. The valve body 44 has a valve body spring rest 48 and the valve needle 46 comprises a valve needle spring rest 50, both spring rests 48, 50 supporting a spring 52 arranged between the valve body 44 and the valve needle 46. Between the valve needle 46 and the valve body 44 a bellow 54 is arranged, which is sealingly coupling the valve body 44 with the valve needle 46. By this a fluid flow between the recess 38 and a chamber 56 is prevented. Furthermore, the bellow 54 is formed and arranged in a way that the valve needle 46 is actuable by the solid state actuator unit 12.
A fluid outlet portion 58 is closed or open depending on the axial position of a valve needle 46. By changing its length, the solid state actuator 16 can exert a force to the valve needle 46. The force from the solid state actuator 16 being exerted on the valve needle 46 in an axial direction allows or respectively prevents a fluid flow through the fluid outlet portion 58. Furthermore, the injection valve 28 has a fluid inlet portion 60, which is arranged in the housing body 34, 36 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 bar.
The valve assembly 30 is arranged in the injection valve 28 facing the first axial end area 24 on the drive side of the solid state actuator unit 12 in a part of the recess 38 of the housing body 34 of the injection valve 28 along the longitudinal axis A.
The compensator unit 14, which is in this example a thermal compensator unit, is arranged facing the second axial end area 26 of the solid state actuator unit 12 and is mechanically coupled to the connecting element 18 of the solid state actuator unit 12. In particular, the compensator unit 14 enables to set an axial preload force on the solid state actuator unit 12 via the connecting element 18 to compensate changes of the fluid flow through the fluid outlet portion 58 in the case of temperature changes of the injection valve 28.
The injection valve 28 further comprises the connector 32 with a non-conductive connector body 62 in which an electric conductor 64 is arranged. Electric energy can be supplied to the electric conductor 64 of the connector 32. Furthermore, the solid state actuator unit 12 comprises an adapter 66 comprising terminal elements 68. The electric conductor 64 of the connector 32 is electrically coupled to one of the terminal elements 68 of the adapter 66 which is electrically coupled to another of the terminal elements 68 which on its part is electrically coupled to the electric pins 20 of the solid state actuator 16. Consequently, electric energy can be simply supplied to the solid state actuator 16 or respectively taken away from the solid state actuator 16 via the connector 32.
The connecting element 18 is arranged in-between the solid state actuator 16 and the compensator unit 14, wherein the connecting element 18 may be conterminous to a spring rest of the compensator unit 14.
In the following, the function of the injection valve 28 will be described in detail:
The fluid is led from the fluid inlet portion 60 through the housing body 34, 36 to the fluid outlet portion 58.
The valve needle 46 prevents a fluid flow through the fluid outlet portion 58 in the valve body 44 in a closing position of the valve needle 46. Outside of the closing position of the valve needle 46, the valve needle 46 enables the fluid flow through the fluid outlet portion 58.
The solid state actuator 16 may change its axial length if it is energized. By changing its length the solid state actuator 16 may exert a force on the valve needle 46. The valve needle 46 is able to move in axial direction out of the closing position. Outside the closing position of the valve needle 46 there is a gap between the valve body 44 and the valve needle 46 at the first axial end area 24 of the injection valve 28 facing away from the solid state actuator 16. The spring 52 can force the valve needle 46 via the valve needle spring rest 50 towards the solid state actuator 16. In the case the solid state actuator 16 is de-energized, the solid state actuator 16 shortens its length. The spring 52 can force the valve needle 46 to move in axial direction in its closing position. It is depending on the force balance between the force on the valve needle 46 caused by the solid state actuator 16 and the force on the valve needle 46 caused by the spring 52 whether the valve needle 46 is in its closing position or not.

Claims

Actuator arrangement (10), comprising
- a solid state actuator unit (12) with a longitudinal axis (A) comprising
- a solid state actuator (16),

- a connecting element (18) for connecting the solid state actuator (16) to a compensator unit (14),

- electric pins (20) being electrically coupable to a power supply, and

- a supporting element (22) being designed and arranged to at least partly take in the connecting element (18) and the electric pins (20),
wherein the solid state actuator unit (12) comprises a first axial end area (24) designed to act as drive side and a second axial end area (26) facing away from the first axial end area (24),

- the compensator unit (14) being arranged facing the second axial end area (26) of the solid state actuator unit (12) along the longitudinal axis (A) of the solid state actuator unit (12) and being in contact with the solid state actuator unit (12) via the connecting element (18) and characterized in that the connecting element (18) being locked within the supporting element (22) and the solid state actuator (16).
Actuator arrangement (10) according to claim 1, wherein the connecting element (18) is fully hardened.
Actuator arrangement (10) according to one of the preceding claims, wherein the connecting element (18) comprises stainless steel.
Actuator arrangement (10) according to one of the preceding claims, wherein the supporting element (22) comprises stainless steel.
Actuator arrangement (10) according to claim 4, wherein the stainless steel comprises around 0.05% carbon, 18% chromium and 10% nickel.
Injection valve (28) with a valve assembly (30) within a recess (38) of a housing body (34, 36) and an actuator arrangement (10) according to one of the preceding claims, comprising a solid state actuator unit (12) within the recess (38), wherein the solid state actuator unit (12) is designed for acting on the valve assembly (30).