Conductive polymer drive for actuating eccentric members of a motor

Abstract

A gear drive assembly (33) includes a housing (24), an external base (28) movable with respect to the housing, and an external gear member (12) associated with the external base. The assembly includes an internal gear member (14) surrounded by the external gear member and in meshing relation therewith. The assembly also includes a plurality of conductive polymer actuators (26) defining actuator sets. Each actuator set is coupled at one portion thereof to the housing with another portion thereof being coupled to the external base. Each actuator is constructed and arranged to deflect when voltage is applied thereto such that when voltage is selectively applied to the actuator sets, deflection of the actuators causes the external base to move causing the external gear member to move in an orbiting manner with respect to the internal gear member.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood from the following detailed description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like parts, in which:

FIG. 1 is a view of conventional eccentric gear assembly for use in a motor.

FIGS. 2 a-2d show conventional movement of an external gear base, of an eccentric gear assembly, by actuators.

FIGS. 3 a-3d show the phases of motion of a conventional eccentric gear.

FIG. 4 is an enlarged view of a conductive polymer drive assembly in accordance with the principles of an embodiment of the present invention.

FIG. 5 is a view of the drive assembly of FIG. 4 driving an eccentric gear assembly.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT

There is a need to be able to cause motion of an eccentric gear assembly without using the conventional, numerous and expensive electro-mechanical actuators, such as the type shown in FIG. 2.

Accordingly, if a planar film of an elastomeric polymer with dielectric properties is coated on its opposing sides with a compliant thin film of conducting material, it becomes a variable capacitor device that changes shape when voltage is applied. One such device is disclosed in U.S. Pat. No. 6,583,533, the content of which is hereby incorporated by reference into this specification. A variety of polymer materials may be used for such devices, depending on the desired performance and operating conditions. When a voltage is applied to the electrodes, the Maxwell stress from the static charge on each electrode film compresses the dielectric elastic polymer in thickness. In addition, the repulsive forces resulting from the like charges on each electrode act to increase the area of the structure. Because the polymer sandwiched between the electrode films acts as an incompressible fluid, the volume of the film tends to remain constant when a force is applied in one dimension. As the force from the electrode films causes the thin film to get thinner (decreasing in the Z dimension), the X and Y dimensions increase to maintain a constant volume. Thus, electrical energy is converted into mechanical motion.

The properties of the above-mentioned electro-active polymer device include high energy and power density, high energy conversion efficiency, quiet operation, simple fabrication with few parts and low-cost component material compared to traditional electric motors. The performance of electro-active polymer systems exceeds that of electromagnetic technology.

Thus, employing the above principles and with reference to FIG. 4, a conductive polymer drive assembly is shown, generally indicated at 22, in accordance with an embodiment of the present invention. The drive assembly 22 includes a housing 24 and a plurality of conductive polymer actuators or piezoelectric elements 26 and an external gear base 28. The housing 24 has surface defining a generally annular opening 23. The actuators are disposed in the opening 23. The actuators 26 preferably of the type disclosed in U.S. Pat. No. 6,583,533, constructed and arranged to change shape or deflect when voltage is applied. The actuators 26 form a generally annular shape between the housing and the external gear base 28. Thus, the actuators 26 form sector bars around an axis of an eccentric gear assembly. In the embodiment, the actuators 26 are attached to each other to define arc-shaped sets 34 of conductive polymer members or piezoelectric elements. Four sets 34 are shown. One end 30 of each set 34 is attached to the housing 24 (via tab 29 extending into opening 23) and the other end 32 is attached to the external gear base 28 (via tab 31). A space 27 is associated with each set 34 of actuators 26 to accommodate deflection of the actuators 26 as will be explained below.

The base 28 is movable with respect to the housing 24 and is associated with the external gear or member 12 (FIG. 5) via leading pins 36. Drive member or external gear 12 has internal gear teeth 35 that mesh with external teeth 37 of the internal gear 14 in the conventional manner. The drive assembly 22, together with the external gear 12 and the internal gear 14 define a gear drive assembly, generally indicated at 33. Hence, selectively energizing the sets 34 of actuators 26 (e.g., applying voltage via wires W) causes orbital motion of the external gear base 28 and the attached leading pins 36 which produces motion of the external gear 12 similar to that of FIG. 2a-2d, but without using the mechanical actuators 22. This causes the internal gear and thus shaft 40 coupled thereto to rotate. The leading pins 36 also help to limit displacements, and can be of the type disclosed in U.S. Pat. No. 5,324,240, or U.S. Pat. No. 1,089,181, the content of each of these patents is hereby incorporated by reference into this specification. In the embodiment, the leading pins 36 are disposed in opening 38 that are larger than the diameter of the pins 36. The pins 36 are used to transfer motion of the gear base 28 to the external gear 12 or can be driven to directly move the external gear 12, thus providing driving orbital motion especially when the source of motion cannot be controlled by an X-Y displacement.

The leading pins are optional, since the external member 12 can be driven by the actuators 26 to move the external gear 12.

The location of the leading pins 36 can be generally centered with respect each set 34 of actuators 26 or, as shown in FIG. 4, can be angular varying to be generally adjacent to the ends of the sets 34 of actuators 26.

The internal gear 14 is coupled with a shaft 40 so that the drive assembly 22 (FIG. 4) and thus the gear drive assembly 33 (FIG. 5) are useful in vehicle window lift motors. However, the gear assembly 33 can be used in vehicle power seat motors and in non-automotive electric motors. The use of the actuators 26 reduces cost of the drive assembly 22 since no conventional electro-mechanical actuators are required.

The foregoing preferred embodiments have been shown and described for the purposes of illustrating the structural and functional principles of the present invention, as well as illustrating the methods of employing the preferred embodiments and are subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within the spirit of the following claims.

Claims

1. A drive assembly for moving eccentric members of a motor, the eccentric members including an external member and a cooperating internal member surrounded by the external member, the drive assembly comprising: a housing,an external base constructed and arranged to be associated with the external member, anda plurality of conductive polymer actuators defining actuator sets, each actuator set being coupled at one portion thereof to the housing with another portion thereof being coupled to the external base, each actuator being constructed and arranged to deflect when voltage is applied thereto such that when voltage is selectively applied to the actuator sets, deflection of the actuators causes the external base to move with respect to the housing.

2. The drive assembly of claim 1, wherein each actuator set is of generally arc shape and together the sets define a generally annular shape between the housing and the external base.

3. The drive assembly of claim 1, in combination with the external member, the external member being associated with the external base such that movement of the base moves the external member.

4. A gear drive assembly comprising: a housing,an external base movable with respect to the housing,an external gear member associated with the external base, the external gear member having internal gear teeth,an internal gear member surrounded by the external gear member and having external gear teeth, the external gear teeth being constructed and arranged to mesh with the internal gear teeth, anda plurality of conductive polymer actuators defining actuator sets, each actuator set being coupled at one portion thereof to the housing with another portion thereof being coupled to the external base, each actuator being constructed and arranged to deflect when voltage is applied thereto such that when voltage is selectively applied to the actuator sets, deflection of the actuators causes the external base to move causing the external gear member to move in an orbiting manner with respect to the internal gear member.

5. The gear drive assembly of claim 4, wherein each actuator set is of generally arc shape and together the actuator sets define a generally annular shape between the housing and the external base.

6. The gear drive assembly of claim 5, wherein four actuator sets are provided.

7. The gear drive assembly of claim 4, wherein the internal gear member is coupled with a shaft.

8. The gear drive assembly of claim 5, wherein the housing has surfaces defining a generally annular opening, the actuator sets being disposed in the opening.

9. The gear drive assembly of claim 8, wherein the housing includes tabs extending into the opening, the one portion of each actuator set being coupled to an associated tab.

10. The gear drive assembly of claim 9, wherein the external base includes a plurality of tabs, the another portion of each actuator set being coupled to an associated tab of the external base.

11. The gear drive assembly of claim 4, further including a plurality of leading pins coupled to the external base, the external gear member having surfaces defining openings, each opening receiving an associated leading pin, each opening being larger than a diameter of the leading pin, the leading pins transferring motion of the external base to the external gear member upon engaging the surfaces defining the openings.

12. The gear drive assembly of claim 11, wherein four evenly spaced leading pins are provided.

13. The gear drive assembly of claim 6, further including a plurality of leading pins coupled to the external base, the external gear member having surfaces defining openings, each opening receiving an associated leading pin, each opening being larger than a diameter of the leading pin, the leading pins transferring motion of the external base to the external gear member upon engaging the surfaces defining the openings.

14. The gear drive assembly of claim 13, wherein four evenly spaced leading pins are provided with each pin being generally adjacent to an end of an associated actuator set.

15. A method of causing an external gear member to move about an internal gear member, the method comprising: providing a housing; an external base movable with respect to the housing; an external gear member associated with the external base, an internal gear member surrounded by the external gear member and operatively associated therewith; and a plurality of conductive polymer actuators coupled between the housing and the external base, andapplying voltage to the actuators causing the actuators to deflect and thereby causing the external base to move causing the external gear member to move in an orbiting manner with respect to the internal gear.

16. The method of claim 15, wherein the actuators define actuator sets and each actuator set is of generally arc shape and together the actuator sets define a generally annular shape between the housing and the external base, the method including: applying voltage to the actuator sets causing the actuator of the set to deflect.

17. The method of claim 15, further providing a plurality of leading pins coupled to the external base, the external gear member having surfaces defining openings, each opening receiving an associated leading pin, each opening being larger than a diameter of the leading pin, the method including: transferring motion of the external base to the external gear member by the leading pins upon the leading pins engaging the surfaces defining the openings.

18. The method of claim 17, wherein four evenly spaced leading pins are provided.