Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
1999-03-30
2001-02-27
Budd, Mark O. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C123S446000
Reexamination Certificate
active
06194812
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a controller with an actuator having a controllable length that is accommodated in a housing. The invention also relates to a device for transmitting a deflection of an actuator, in particular of a piezoelectric actuator.
A controller with a piezoelectric actuator is used in automotive engineering, for instance for opening an injection valve of an internal combustion engine. A longitudinal motion of the piezoelectric actuator is transmitted through a suitable configuration to an associated valve closing member, which relieves a back side of a pressure-loadable nozzle needle and thus enables a targeted opening and closure of the injection nozzle.
A piezoelectric actuator, which is known from UK Patent Application GB 2 193 386 A, rests on a diaphragm that defines a pressure chamber which is filled with hydraulic fluid, along with portions of a valve housing and a tappet disposed movably in a guide bore. The diaphragm protects the piezoelectric actuator from being wetted with the hydraulic fluid. The diaphragm is disposed substantially perpendicular to the direction of deflection of the piezoelectric actuator and is secured laterally in the valve housing.
Another version also protects the tappet against being wetted with the hydraulic fluid. There the pressure chamber is defined by a first bellows, which has a platform-like part on which the piezoelectric actuator rests and which extends substantially perpendicular to the direction of motion of the piezoelectric actuator and is tightly joined to the valve housing. The tappet, which is disposed movably in a guide bore, is also joined to the valve housing by a second bellows, which is disposed perpendicular to the direction of motion of the tappet inside the guide bore. The first bellows and the second bellows form a pressure chamber filled with hydraulic fluid. The piezoelectric actuator, as well as the tappet, are both being protected against being wetted with the hydraulic fluid.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a controller with an actuator of controllable length and a device for transmitting the deflection of an actuator, which overcome the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type, which transmit the deflection of an actuator to a tappet, in which the tappet and the actuator are protected against being wetted by an operating fluid and in which a defined motion of the tappet in a guide bore is assured.
With the foregoing and other objects in view there is provided, in accordance with the invention, a controller, comprising a housing having a guide conduit; an actuator accommodated in the housing and having a longitudinal direction and a controllable length; a tappet guided in the guide conduit; a pressure chamber disposed between the actuator and the tappet and filled with an operating medium; at least a first and a second diaphragm disposed crosswise to the longitudinal direction of the actuator and defining the pressure chamber; the first diaphragm associated with the actuator and the second diaphragm associated with the tappet, for causing a deflection of the actuator through the first diaphragm, the operating medium and the second diaphragm to lead to a displacement of the tappet; the first and second diaphragms having equal surface areas; the first and second diaphragms having effective surface areas with which the first and second diaphragms are to be deflected; and the effective surface area of the second diaphragm being less than the effective surface area of the first diaphragm; the guide conduit having a given diameter, and the effective surface area of the second diaphragm predetermined by the given diameter.
In accordance with another feature of the invention, the operating medium is under pressure in the pressure chamber, and the first diaphragm permits the operating medium to exert a force on the actuator prestressing the actuator counter to a deflection direction.
In accordance with a further feature of the invention, the operating medium has a coefficient of thermal expansion compensating for different coefficients of thermal expansion of the actuator and the housing.
In accordance with an added feature of the invention, the actuator has a first area operatively connected to the first diaphragm, the tappet has a second area operatively connected to the second diaphragm, and the first area is larger than the second area.
With the objects of the invention in view there is also provided a device for transmitting a deflection of an actuator, in particular a piezoelectric actuator, comprising a substrate part having first and second recesses formed therein; a first diaphragm tightly joined to the substrate part and tightly closing off the first recess; a second diaphragm tightly joined to the substrate part and tightly closing off the second recess; a connecting conduit disposed in the substrate part and interconnecting the first and second recesses; and the first recess, the second recess and the connecting conduit forming a closed pressure chamber filled with an operating medium.
In accordance with another feature of the invention, the first diaphragm has an area defining the first recess, the second diaphragm has an area defining the second recess, and the area of the first diaphragm is larger than the area of the second diaphragm.
In accordance with a further feature of the invention, the second diaphragm has a lesser rigidity than the first diaphragm and sags farther than the first diaphragm under the same pressure.
In accordance with an added feature of the invention, the operating medium in the pressure chamber has a predetermined pressure.
In accordance with an additional feature of the invention, one of the diaphragms is constructed at least in part of fabric-reinforced plastic, in particular an elastomer.
In accordance with a concomitant feature of the invention, there is provided a filler piece which is disposed between the first and second diaphragms and is preferably adapted to a shape of one of the diaphragms, the filler piece permitting the pressure chamber formed by the first and second diaphragms to be constructed with a small volume, regardless of the shape of the first and second diaphragms.
One substantial advantage of the invention is that the tappet in the guide bore is not hindered in its motion by a bellows, and therefore the tappet can be adapted precisely to the dimensions of the guide bore, and as a result canting in the motion of the tappet can be reliably avoided.
It is also advantageous that a compact transmission device is provided which can be manufactured separately from a housing and then mounted in the housing in a simple way.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a controller with an actuator of controllable length and a device for transmitting the deflection of an actuator, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
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patent: 4803393 (1989-02-01), Takahashi
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patent: 4909440 (1990-03-01), Mitsuyasu et al.
patent: 5821671 (1998-10-01), Trzmiel
patent: 37 13 697 A1 (1988-11-01), None
patent: 44 07 962 C1 (1995-06-01), None
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patent: 0 535 510 A1 (1993-04-01), None
patent: 2 193 386 (1988-
Baranowski Dirk
Fitzner Johannes
Giavi Raimondo
Kirchweger Karl
Klugl Wendelin
Budd Mark O.
Greenberg Laurence A.
Lerner Herbert L.
Siemens Aktiengesellschaft
Stemer Werner H.
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