Piezo actuator

• US 20030168937A1
• Filed: 05/09/2003
• Published: 09/11/2003
• Est. Priority Date: 05/25/2000
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Heinz, Rudolf, Boecking, Friedrich, Hedrich, Alexander
• Granted Patent: US 6,781,289 B2
• Time in Patent Office: Days
• US Class Current: 310/328
• CPC Class Codes: F02M 2200/21 Fuel-injection apparatus with piezoelectric or magnetostrictive elements
• CPC Class Codes: F02M 2200/26 Fuel-injection apparatus with elastically deformable elements other than coil springs
• CPC Class Codes: H10N 30/50 having a stacked or multilayer structure
• CPC Class Codes: H10N 30/886 Mechanical prestressing means, e.g. springs springs in general F16F1/00

Abstract

A piezoelectric actuator (1) is proposed, in which a piezoelectric element (2) is present for subjecting an actuating element to a tensile or compressive stress. A sleeve (4; 20) is secured to a foot part (3), to which the piezoelectric element (2) is secured and by way of which the piezoelectric element (2) is kept centered in a housing (8) under mechanical prestressing, and this sleeve surrounds the piezoelectric element (2) in such a way as to stabilize it mechanically, at least in partial regions that are electrically insulated from the piezoelectric element. Between the sleeve (4; 20) and the piezoelectric element (2), a heat-conducting elastomer (6) is placed, and the sleeve (4; 20) comprises a heat-conducting material that is deformable within predetermined limits.

Claims

1. A piezoelectric actuator, having

at least one piezoelectric element for subjecting an actuating element to a tensile or compressive stress, and having

a foot part (3) to which the piezoelectric element (2) is secured and by way of which the piezoelectric element (2) is kept centered in a housing (8) under a mechanical prestressing, characterized in that

a sleeve (4;

20) is secured to the foot part (3) and surrounds the piezoelectric element (2) in such a way as to stabilize it mechanically, at least in partial regions that are electrically insulated from the piezoelectric element.

2. The piezoelectric actuator of claim 1, characterized in that

a heat-conducting elastomer (6) is placed between the sleeve (4;

20) and the piezoelectric element (2).

3. The piezoelectric actuator of claim 1 or 2, characterized in that

the sleeve (4;

20) comprises a heat-conducting material that is deformable within predetermined limits.

4. The piezoelectric actuator of claim 3, characterized in that

the sleeve (4;

20) is of metal, preferably copper or steel.

5. The piezoelectric actuator of claim 3, characterized in that

the sleeve (4;

20) is of plastic.

6. The piezoelectric actuator of one of the foregoing claims, characterized in that

the sleeve (4;

20) together with the piezoelectric element (2) can be press-fitted firmly into a suitable retaining bore (5) in the housing (8) for the piezoelectric actuator (1), optionally via an oblique shoulder (7) on the periphery of the retaining bore (5).

7. The piezoelectric actuator of one of the foregoing claims, characterized in that

the sleeve (20) has recesses (21, 23, 24, 25), preferably holes (21) or oblong slots (24), in its wall.

8. The piezoelectric actuator of one of the foregoing claims, characterized in that

the foot part (3) has an encompassing groove (27), into which a likewise encompassing bead (28) can be latched on the inside diameter of the sleeve (4;

20).

9. The piezoelectric actuator of one of the foregoing claims, characterized in that

centering rings (17) are placed between the piezoelectric element (2) and the sleeve (4;

20).

10. The piezoelectric actuator of one of claims 7-9, characterized in that

after the piezoelectric element (2) with the sleeve (20) has been inserted into a retaining bore (5) in the housing (8) for the piezoelectric actuator (1), the remaining interstices in the retaining bore (5) can be filled at least partially with a heat-conducting elastomer (6).