Linear motor

• US 5,055,725 A
• Filed: 11/13/1989
• Issued: 10/08/1991
• Est. Priority Date: 11/13/1989
• Status: Expired due to Fees

• Current Assignee: Laurence Lasota
• Original Assignee: Laurence Lasota
• Inventors: LaSota, Laurence
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): JONES, JUDSON
• Application Number:
  US07/435,564
• Time in Patent Office: 694 Days
• Field of Search: 310/12, 310/13, 310/14, 310/15, 310/16, 310/17, 310/18, 310/19, 310/20, 310/23, 318/135, 335/253, 335/254, 335/255, 335/77
• US Class Current: 310/14
• CPC Class Codes: H02K 7/06 Means for converting reciprocating motion into rotary motion or vice versa

Abstract

A linear motor provides stepwise, incremental advance of a movable member. A linear motor includes an electric coil surrounded by a magnetic core. A co-axially aligned magnetic movable pole member and a magnetic plunger extend through the core and coil. Opposed faces of the movable pole member and the plunger are separated by an air gap. A biasing spring is connected between the plunger and the pole member to bias the pole member away from the plunger when electric current has been removed from the coil to re-establish the air gap between the pole member and the plunger. Latches act on the pole member and the plunger to provide unidirectional movement of the pole member and plunger when a magnetic field induced in the core when current is applied to the coil causes advance of the plunger into contact with the pole member. When current is removed from the coil, the magnetic field collapses and the biasing spring urges the pole member away from the plunger to re-establish the air gap for the next sequential energization of the coil. A latch release device is provided to release the latches and enable the pole member and the plunger to be retracted to a start position. In one embodiment, pairs of latches are associated in an opposite orientation with each of the pole member and the plunger. A latch control mechanism switches the latches between positions to provide bi-directional, incremental advance over the pole member and the plunger in opposite directions.

Claims

1. A linear motor comprising:

a coil formed of a plurality of windings;

a magnetic core surrounding the coil;

a magnetic pole member movably disposed within and extending partially outward from one end of the coil and the core;

a magnetic plunger movably disposed within and extending partially outward from another end of the coil and the core, the plunger being co-axially aligned with the pole member and normally spaced from one end of the pole member by an air gap;

the core, the pole member and the plunger forming a magnetic flux path when current is applied to the coil to urge the plunger into contact with the pole member to close the air gap therebetween;

biasing means, connected between the pole member and the plunger, for biasing the pole member and the plunger apart to re-establish the air gap therebetween and to advance the pole member an incremental distance equal to the length of the air gap; and

unidirectional latch means for allowing successive one direction movements of the pole member and the plunger with respect to the core and the coil upon each successive energization and de-energization of the coil.

2. The linear motor of claim 1 wherein the biasing means comprises:

a coil spring having first and second ends, the first end acting on the pole member and the second end acting on the plunger.

5. The linear motor of claim 1 wherein the unidirectional latch means comprises:

a first pair of latches associated with and acting on the pole member and a second pair of latches associated with and acting on the plunger;

each latch of each of the first and second pair of latches comprising;

a wedge member having a first flat surface and a second flat surface inclined with respect to the first surface;

a post;

the inclined surface of the wedge member acting on the post; and

biasing means urging each wedge member to a first position in which each wedge member is wedged between the post and one of the pole member and plunger to prevent movement of the pole member and the plunger in one direction, but allowing movement of the pole member and the plunger in an opposite direction.

6. The linear motor of claim 1 wherein the unidirectional latch means comprises:

a first pair of latches associated with and acting on the pole member;

a second pair of latches associated with and acting on the plunger;

each latch of the first and second pair of latches comprising an eccentric cam;

biasing means acting on each of the cams of the first and second pair of latches for biasing each of the cams to a first position in which the eccentric portions of the cams in each pair of latches engages one of the pole member and plunger to prevent movement of the pole member and the plunger in a first direction, but allowing movement of the pole member and the plunger in an opposite, reverse direction.

9. The linear motor of claim 1 wherein the unidirectional latch means comprises:

a pair of end plates, each mounted on and extending outward from opposite ends of the magnetic core;

first and second pairs of sprags associated with and acting on the pole member and plunger, respectively;

each of the first and second pairs of sprags comprising;

opposed notches formed in each end plate mounted on the end of the magnetic core;

a pair of links engaging one of the pole member and the plunger at one end and the notches at another end; and

means for biasing the links of each of the first and second pairs of sprags into a first position in which the links are wedged between the notch and one of the pole member and the plunger to prevent movement of the pole member and the plunger in one direction, but allowing movement of the pole member and the plunger in a opposite direction.

10. The linear motor of claim 1 further including:

latch release means for releasing the unidirectional latch means to enable retraction of the pole member and the plunger to a start position in a direction opposite to the direction of advance movement of the pole member and the plunger.

3. A linear motor comprising:

a coil formed of a plurality of windings;

a magnetic core surrounding the coil;

a magnetic pole member movably disposed within and extending partially outward from one end of the coil and the core;

a magnetic plunger movably disposed within and extending partially outward from another end of the coil and the core, the plunger being co-axially aligned with the pole member and normally spaced from one end of the pole member by an air gap;

the core, the pole member and the plunger forming a magnetic flux path when current is applied to the coil to urge the plunger into contact with the pole member to close the air gap therebetween;

biasing means, connected between the pole member and the plunger, for biasing the pole member and the plunger apart to reestablish the air gap therebetween and to advance the pole member an incremental distance equal to the length of the air gap, the biasing means including;

a tubular sleeve surrounding the opposed ends of the pole member and the plunger and the air gap therebetween;

pin means extending through the opposed ends of the pole member and the plunger and disposed in opposite ends of the sleeve for mounting the sleeve to the pole member and the plunger;

a coil spring surrounding the tubular sleeve, the coil spring having first and second ends each joined to one of the pin means such that the first end of the spring acts on the pole member and the second end of the spring acts on the plunger; and

a slot formed in one end of the tubular sleeve and receiving one of the pins means therethrough, the slot defining the length of the air gap when the biasing means urges the pole member and the plunger apart; and

unidirectional latch means for allowing successive one direction movements of the pole member and the plunger with respect to the core and the coil upon each successive energization and deenergization of the coil.

4. A linear motor comprising:

a coil formed of a plurality of windings;

a magnetic core surrounding the coil;

a magnetic pole member movably disposed within and extending partially outward from one end of the coil and the core;

a magnetic plunger movably disposed within and extending partially outward from another end of the coil and the core, the plunger being co-axially aligned with the pole member and normally spaced from one end of the pole member by an air gap;

the core, the pole member and the plunger forming a magnetic flux path when current is applied to the coil to urge the plunger into contact with the pole member to close the air gap therebetween;

biasing means, connected between the pole member and the plunger, for biasing the pole member and the plunger apart to re-establish the air gap therebetween and to advance the pole member an incremental distance equal to the length of the air gap; and

unidirectional latch means for allowing successive one direction movements of the pole member and the plunger with respect to the core and the coil upon each successive energization and deenergization of the coil, the unidirectional latch means including;

at least one first latch associated with and acting on the pole member and at least one second latch associated with and acting on the plunger;

each of the first and second latches comprising;

a plate member having first and second angularly disposed legs;

an aperture formed in one of the first and second legs of the plate member and slidably receiving one of the pole member and the plunger therethrough; and

means, connected between the magnetic core and the first and second latches, for biasing the first and second latches to a first position in which the pole member and the plunger are freely moveable in one direction therethrough and a second position in which the plate member of the first and second latches engages the pole member and the plunger to prevent movement of the pole member and the plunger in an opposite direction.

7. A linear motor comprising:

a coil formed of a plurality of windings;

a magnetic core surrounding the coil;

a magnetic pole member movably disposed within and extending partially outward from one end of the coil and the core;

a magnetic plunger movably disposed within and extending partially outward from another end of the coil and the core, the plunger being co-axially aligned with the pole member and normally spaced from one end of the pole member by an air gap;

the core, the pole member and the plunger forming a magnetic flux path when current is applied to the coil to urge the plunger into contact with the pole member to close the air gap therebetween;

first biasing means, connected between the pole member and the plunger, for biasing the pole member and the plunger apart to re-establish the air gap therebetween and to advance the pole member an incremental distance equal to the length of the air gap;

unidirectional latch means for allowing successive one direction movements of the pole member and the plunger with respect to the core and the coil upon each successive energization and deenergization of the coil; and

first and second end caps attached to opposite ends of the magnetic core;

the unidirectional latch means further comprising;

first and second angularly disposed planar, ramp surfaces formed in each of the first and second end caps;

a roller disposed between and acting on each ramp surface and one of the pole member and the plunger; and

second biasing means for urging each roller to a first position in which the roller is wedged between the ramp surface and one of the pole member and plunger to prevent movement of the pole member and the plunger in one direction, but allowing movement of the pole member and the plunger in an opposite direction.

8. A linear motor comprising:

a coil formed of a plurality of windings;

a magnetic core surrounding the coil;

a magnetic pole member movably disposed within and extending partially outward from one end of the coil and the core;

a magnetic plunger movably disposed within and extending partially outward from another end of the coil and the core, the plunger being co-axially aligned with the pole member and normally spaced from one end of the pole member by an air gap;

the core, the pole member and the plunger forming a magnetic flux path when current is applied to the coil to urge the plunger into contact with the pole member to close the air gap therebetween;

biasing means, connected between the pole member and the plunger, for biasing the pole member and the plunger apart to re-establish the air gap therebetween and to advance the pole member an incremental distance equal to the length of the air gap; and

unidirectional latch means for allowing successive one direction movements of the pole member and the plunger with respect to the core and the coil upon each successive energization and deenergization of the coil, the unidirectional latch means including;

each of the pole member and the plunger having a plurality of angularly disposed teeth formed on an exterior portion thereof;

a first pair of pawls associated with and engaging the teeth on the pole member;

a second pair of pawls associated with and engaging the teeth on the plunger; and

means, connected between each of the first and second pairs of pawls, for urging the pawls in each of the first and second pairs of pawls to a first position engaging the teeth on the pole member and the plunger to allow unidirectional movement of the pole member and the plunger in one direction and preventing movement of the pole member and plunger in an opposite direction.

11. A linear motor comprising:

a coil formed of a plurality of windings;

a magnetic core surrounding the coil;

a magnetic pole member movably disposed within and extending partially outward from one end of the coil and the core;

a magnetic plunger movably disposed within and extending partially outward from another end of the coil and the core, the plunger being co-axially aligned with the pole member and normally spaced from one end of the pole member by an air gap;

the core, the pole member and the plunger forming a magnetic flux path when current is applied to the coil to urge the plunger into contact with the pole member to close the air gap therebetween;

biasing means, connected between the pole member and the plunger, for biasing the pole member and the plunger apart to re-establish the air gap therebetween and to advance the pole member an incremental distance equal to the length of the air gap;

unidirectional latch means for allowing successive one direction movements of the pole member and the plunger with respect to the core and the coil upon each successive energization and de-energization of the coil; and

latch release means for releasing the unidirectional latch means to enable retraction of the pole member and the plunger to a start position in a direction opposite to direction of advance movement of the pole member and the plunger, the latch release means including;

first and second end caps fixedly mounted in opposite ends of the magnetic core, the first and second end caps being formed of a non-ferrous material;

first and second magnets of opposite polarity slidably disposed within opposite ends of the magnetic core inward of the first and second end caps, respectively, and forming a part of the magnetic core flux path;

the pole member and the plunger slidably extending through the first and second end caps and the first and second permanent magnets, respectively; and

at least one pin connected to each of the first and second permanent magnets and acting on the unidirectional latch means spaced from the first and second permanent magnets such that when the first and second magnets slide outward from the coil when an electric current of one polarity is applied to the coil, the pin moves the latch means to a position allowing movement of the pole member and the plunger in a direction opposite the direction of incremental advance of the pole member and the plunger.

12. A linear motor comprising:

a coil formed of a plurality of windings;

a magnetic core surrounding the coil;

a magnetic pole member movably disposed within and extending partially outward from one end of the coil and the core;

a magnetic plunger movably disposed within and extending partially outward from another end of the coil and the core, the plunger being co-axially aligned with the pole member and normally spaced from one end of the pole member by an air gap;

the core, the pole member and the plunger forming a magnetic flux path when current is applied to the coil to urge the plunger into contact with the pole member to close the air gap therebetween;

biasing means, connected between the pole member and the plunger, for biasing the pole member and the plunger apart to reestablish the air gap therebetween and to advance the pole member an incremental distance equal to the length of the air gap;

unidirectional latch means for allowing successive one direction movements of the pole member and the plunger with respect to the core and the coil upon each successive energization and deenergization of the coil; and

latch release means for releasing the unidirectional latch means to enable retraction of the pole member and the plunger to a start portion in a direction opposite to direction of advance movement of the pole member and the plunger, the latch release means including;

first and second end caps fixedly mounted on opposite ends of the magnetic core and formed of a ferrous material;

a solenoid formed of a magnetically coupled core and coil concentrically disposed about the magnetic core of the linear motor;

a plunger associated with the solenoid and slidably mounted on the magnetic core of the linear motor; and

at least one latch release rod connected to the plunger at one end and to each of the unidirectional latch means of the pole member and the plunger at an opposite end;

the pole member being attracted to the solenoid when current of a first polarity is applied to the coil of the solenoid to move the unidirectional latch means through the latch release rods to a position allowing movement of the pole member of the plunger in a direction opposite to the direction of incremental advance of the pole member and the plunger.

13. linear motor comprising:

a coil formed of a plurality of windings;

a magnetic core surrounding the coil;

a magnetic pole member movably disposed within and extending partially outward from one end of the coil and the core;

a magnetic plunger movably disposed within and extending partially outward from another end of the coil and the core, the plunger being co-axially aligned with the pole member and normally spaced from one end of the pole member by an air gap;

the core, the pole member and the plunger forming a magnetic flux path when current is applied to the coil to urge the plunger into contact with the pole member to close the air gap therebetween;

biasing means, connected between the pole member and the plunger, for biasing the pole member and the plunger apart to re-establish the air gap therebetween and to advance the pole member

unidirectional altach means for allowing successive one

unidirectional latch means for allowing successive one direction movements of the pole member and the plunger with respect to the core and the coil upon each successive energization and de-energization of the coil; and

latch release means for releasing the unidirectional latch means to enable retraction of the pole member and the plunger to a start portion in a direction opposite to direction of advance movement of the pole member and the plunger, the latch release means including;

first and second end caps fixedly mounted on opposite ends of the magnetic core and forming a part of the magnetic flux path of the magnetic core;

the pole member and the plunger slidably extending through the first and second end caps, respectively; and

a rod formed of a shape memory material extending between and connected to the magnetic core and the unidirectional latch means associated with each of the pole member and the plunger;

the rod changing shape when heated to cause movement of the unidirectional latch means to a position allowing the pole member and the plunger to be moved in a direction opposite to the direction of incremental advance of the pole member and the plunger.

14. A linear motor comprising:

a coil formed of a plurality of windings;

a magnetic core surrounding the coil;

a first magnetic movable member movably disposed within and extending partially outward from one end of the coil and the core;

a second magnetic movable member movably disposed within and extending partially outward from the other end of the coil and the core, the second magnetic movable member being co-axially aligned with the first magnetic movable member and normally spaced from one end of the first magnetic movable member by an air gap;

the magnetic core and the first and second magnetic movable members forming a magnetic flux path when current is supplied to the coil to urge the second magnetic movable member into contact with the first magnetic movable member to close the air gap therebetween;

biasing means, connected between the first and second magnetic movable members, for biasing the first magnetic movable member and the second magnetic movable member apart to re-establish the air gap therebetween and to advance the second magnetic movable member;

an insulated rod connected to the first magnetic movable member and extending through a bore in the second magnetic movable member;

an output fork spaced from the second magnetic movable member and connected to a movable load, the rod slidably connected to the output fork;

bi-directional latch means, associated with and acting on the first and second magnetic movable members, for allowing selective movement of the first and second magnetic movable members in one direction, while blocking movement of the first and second magnetic movable members in an opposite direction; and

latch control means for moving the bi-directional latch means from positions allowing movement of the first and second magnetic movable members in one direction to positions allowing movement of the first and second magnetic movable members only in a second, opposite direction.

15. The linear motor of claim 14 wherein the bi-directional latch means comprises:

first and second pairs of latches, each of the first and second pair of latches including first and second latch members, each of the first and second pairs of latches respectively associated with the first and second magnetic movable members;

each of the first and second pairs of latches having the first and second latch members thereof arranged in opposite orientation such that one of the first and second latch members of each of the first and second pairs of latches is disposed in a position to prevent movement of the associated magnetic movable member in one direction and to allow movement of the associated magnetic movable member in an opposite direction, while the other of the first and second latch members of each of the first and second pair of latches is disposed to allow movement of the associated first and second magnetic movable members in one direction, but prevents movement of the associated first and second magnetic movable members in an opposite direction.

16. A linear motor comprising:

a coil formed of a plurality of windings;

a magnetic core surrounding the coil;

a first magnetic movable member movably disposed within and extending partially outward from one end of the coil and the magnetic core;

a second magnetic movable member movably disposed within and extending partially outward from the other end of the coil and the magnetic core, the second magnetic movable member being co-axially aligned with the first magnetic movable member and normally spaced from one end of the first magnetic movable member by an air gap;

the magnetic core and the first and second magnetic movable members forming a magnetic flux path when current is supplied to the coil to urge the second magnetic movable member into contact with the first magnetic movable member to close the air gap therebetween;

a rotator body;

a guide rod connected to the second magnetic movable member and extending through the first magnetic movable member to the rotator body;

biasing means extending between one end of the first magnetic movable member and the rotator body;

a contact body rotatably mounted on the rotator body;

an electrical contact mounted in the contact body and electrically connected between an electrical power source and the magnetic coil to carry electric current to the coil; and

means, mounted in the rotator body, for rotating the electrical contact during each operation of the linear motor.