Linear actuator with threaded captivation sleeve, captive lead screw, and spring pre-load adjustment

• US 6,603,229 B1
• Filed: 11/15/2000
• Issued: 08/05/2003
• Est. Priority Date: 11/15/2000
• Status: Expired due to Term

• Current Assignee: Tritex Corp. (Ametek Incorporated)
• Original Assignee: Tri-Tech, Inc. (TTFI Holdings, Inc.)
• Inventors: Toye, Thomas A. IV
• Primary Examiner(s): Ramirez, Nestor
• Assistant Examiner(s): Cuevas, Pedro J.
• Application Number:
  US09/713,083
• Time in Patent Office: 993 Days
• Field of Search: 310/90, 310/15, 310/12, 310/49.R, 310/80, 310/83, 128/205.24, 251/129.11
• US Class Current: 310/90
• CPC Class Codes: F16H 2025/2075 Coaxial drive motors
• CPC Class Codes: F16H 25/20 Screw mechanisms with automatic reversal F16H25/12
• CPC Class Codes: H02K 7/06 Means for converting reciprocating motion into rotary motion or vice versa

Abstract

In a preferred embodiment, a linear actuator, including: front and rear end bells; a stator structure; a rotor structure having first and second bearings journaled, respectively, in cavities formed in inner surfaces of the front and rear end bells; a captivation sleeve having its proximal end threadedly inserted in a cavity formed in an outer surface of the front end bell; and all foregoing elements being coaxially aligned to permit the insertion therethrough of a lead screw.

Claims

1. A linear actuator, comprising:

(a) front and rear end bells;

(b) a stator structure;

(c) a rotor structure having first and second bearings journaled, respectively, in cavities formed in inner surfaces of said front and rear end bells;

(d) a captivation sleeve having its proximal end threadedly inserted in a cavity formed in an outer surface of said front end bell;

(e) all foregoing elements being coaxially aligned to permit the insertion therethrough of a lead screw inserted through coaxially aligned foregoing elements, said lead screw having a threaded portion extending through said rotor structure and a splined portion extending through said captivation sleeve; and

(f) a cylindrical anti-rotation bearing fixedly inserted in a distal end of said captivation sleeve, said anti-rotation bearing having an opening coaxial with said foregoing elements.

2. A linear actuator, as defined in claim 1, wherein:

said proximal end of said captivation sleeve bears against an outer surface of said first bearing to impose a selected pre-load on said first and second bearings by selectively threadedly rotating said captivation sleeve inwardly or outwardly.

3. A linear actuator, as defined in claim 1, further comprising:

a spring disposed between an outer surface of said first bearing and said proximal end of said captivation sleeve such that pre-load of said first and second bearings is determined by strength of said spring and degree of compression of said spring by said proximal end of said captivation sleeve being inserted into said cavity formed in an outer surface of said front end bell.

4. A linear actuator, as defined in claim 1, wherein:

(a) said anti-rotation bearing has anti-rotation tabs molded integrally therewith; and

(b) said captivation sleeve has slots formed in said distal end thereof into which sleeve said anti-rotation tabs closely fit to prevent rotation of said anti-rotation bearing with respect to said captivation sleeve.

5. A linear actuator, as defined in claim 1, wherein:

said captivation sleeve has locking tabs formed in said distal end thereof and bent over an outer surface of said anti-rotation bearing to lock said anti-rotation bearing axially and radially in place in said captivation sleeve.

6. A linear actuator, comprising:

(a) front and rear end bells;

(b) a stator structure;

(c) a rotor structure having first and second bearings journaled, respectively, in cavities formed in inner surfaces of said front and rear end bells;

(d) a captivation sleeve having its proximal end threadedly inserted in a cavity formed in an outer surface of said front end bell;

(e) a lead screw inserted through coaxially aligned foregoing elements, said lead screw having a threaded portion extending through said rotor structure and a splined portion extending through said captivation sleeve; and

(f) a cylindrical anti-rotation bearing fixedly inserted in a distal end of said captivation sleeve, said anti-rotation bearing having an opening coaxial with said foregoing elements.

7. A linear actuator, as defined in claim 6, wherein:

said proximal end of said captivation sleeve bears against an outer surface of said first bearing to impose a selected pre-load on said first and second bearings by selectively threadedly rotating said captivation sleeve inwardly or outwardly.

8. A linear actuator, as defined in claim 7, further comprising:

a spring disposed between an outer surface of said first bearing and said proximal end of said captivation sleeve such that pre-load of said first and second bearings is determined by strength of said spring and degree of compression of said spring by said proximal end of said captivation sleeve being inserted into said cavity formed in an outer surface of said front end bell.

9. A linear actuator, as defined in claim 7, wherein:

(a) said anti-rotation bearing has anti-rotation tabs molded integrally therewith; and

(b) said captivation sleeve has slots formed in said distal end thereof into which sleeve said anti-rotation tabs closely fit to prevent rotation of said anti-rotation bearing with respect to said captivation sleeve.

10. A linear actuator, as defined in claim 7, wherein:

said captivation sleeve has locking tabs formed in said distal end thereof and bent over an outer surface of said anti-rotation bearing to lock said anti-rotation bearing axially and radially in place in said captivation sleeve.