GB2043826A

GB2043826A - Rotary Drive Device

Info

Publication number: GB2043826A
Application number: GB7940891A
Authority: GB
Original assignee: Borg Warner Corp
Current assignee: Borg Warner Corp
Priority date: 1979-03-01
Filing date: 1979-11-27
Publication date: 1980-10-08
Also published as: FR2450390A1; JPS55119230A; DE2950448A1

Abstract

A speed-changing drive apparatus comprises a oneway clutch having a plurality of oneway cams or sprags (16), between a pair of concentric rings (12, 14), in combination with a friction strain wave gear. Rotation of an input member 26 causes distortion of one of the rings providing a travelling wave motion to progressively drivingly engage and drivingly disengage all cams in a sequential manner. With the reaction member held against rotation, oscillation or rotation of the input member in either direction causes a unidirectional rotation of one or more of the output members. <IMAGE>

Description

SPECIFICATION Rotary Drive Device Two-function one-way cam or sprag clutches which transmit torque and motion at 1:1 or zero are well known in the art. Typical clutches are described and claimed in U.S. Patents Numbers 2,824,536 issued to H. P. Troendly et al; 2,856,045 issued to E. A. Ferris; 2,888,116 issued to H. P. Troendly et al and 3,019,873 issued to E. A. Ferris et al.

These typical cam or sprag clutches comprise generally a pair of cylindrical rings or races with a plurality of spring actuated cams or sprags therebetween. When in driving-position, the cams or sprags are wedged between the races to transmit torque therebetween. When the drive member is rotated in the opposite direction, the cams or sprags slide or lift off one of the races and the driving connection no longer exists, i.e., the clutch freewheels. If the driver element is oscillated against an elastic resistance, the driven element will be intermittently oscillated at a 1:1 torque and angular velocity in one direction, but as a function of the elastic force in the other direction.Conventionally, torque in is equal to torque out, and rpm in is equal to rpm out or zero, by design limitation thereof; and the torque ratio is always 1:1 or zero, depending on the direction of rotation of the input member.

In the conventional cam or sprag clutches, as depicted in the prior art, each clutch also comprises one or more cages which properly space the cams or sprags and one or more springs or springlike members which bias the cams or sprags into contact with the inner and outer rings.

According to this invention, there is provided a speedchanging drive device which comprises a oneway cam or sprag clutch, generally of conventional construction and having an outer ring and an inner ring with sprags or cams therebetween, and an associated input or driving member. The input or driving member is so constructed to be rotatable and to distort one of the clutch rings from a right circular cylindrical configuration to a generally oval configuration.

Upon rotation of the input member in either direction, i.e., clockwise or counterclockwise, the selected driven or output member or members will rotate at a new velocity in one direction only.

Oscillations of the input member are converted to non-oscillating rotations of the output members in one direction. Thus the direction and velocity of rotation of the output member or members is independent of the direction and velocity of rotation of the input member. Bearing or antifriction means with suitable lubrication means are positioned between the input member and the distorted clutch ring. The input member may be such to distort the inner clutch ring or to distort the outer clutch ring and may take several structural forms.

The output members comprise the inner ring of the clutch, the outer ring of the clutch, or the cage, if used, or individually or in combination.

Any one of these members may under some conditions become a reaction member (held against rotation).

While the direction of rotation of each output member is unidirectional, the direction of all output members is not necessarily the same. For example, rotating an input member which distorts the inner ring of a sprag clutch similar to those illustrated in the noted prior art patents in either a clockwise or counterclockwise direction and with the outer ring held stationary as a reaction member results in the inner ring and the cage rotating in a counterclockwise direction. The rates of rotation of the output members, the inner ring and the cage, are different from each other and from the input member.When the cage is held stationary as a reaction member and the input member (which distorts the inner ring of the clutch) is rotated in either a clockwise or counterclockwise direction, the inner ring will rotate in a counterclockwise direction and the outer ring will rotate in a clockwise direction. Here again the rates of rotation are different from each other and from the input member.

While the prior art sprag clutches are adapted to transmit motion at a 1:1 ratio or zero, depending on direction of rotation, a device according to this invention can be constructed to transmit multiple motions at infinitely variable speed ratios, in two directions simultaneously, by varying the degree of distortion (from circular to oval of different degrees) of at least one of the rings.

One way of carrying out the invention is described in detail below with reference to drawings which illustrate only one specific embodiment, in which: Fig. 1 is a plan schematic view of a typical drive apparatus according to this invention; Fig. 2 is a cross-sectional view of the apparatus taken on line 22 of Fig. 1; Fig. 3 is a plan view similar to Fig. 1 illustrating another embodiment of the input member; Figs. 4, 5 and 6 are partial plan views of still other embodiments of an input member to distort the inner ring; Fig. 7 is a plan view, similar to Fig. 1 showing an input member which distorts the outer ring; Fig. 8 is a longitudinal sectional view of onerotor version of this invention; and Fig. 9 is a sectional view taken on line 99 of Fig. 8.

In Figs. 1 and 2 there is illustrated one embodiment of a drive device constructed according to this invention which is identified as 10 and which comprises an outer ring 12 and an inner ring 14 with a plurality of cams or sprags 16 therebetween. The inner and outer rings are normally cylindrical in section. Also shown is a cage 1 8 having a plurality of openings 20 which substantially evenly spaces the cams or sprags 1 6. A spring means 22, illustrated as a ribbon spring with substantially evenly spaced openings 24, urges the sprags 16, when assembled with the rings, toward the outer ring 12. An input means 26 is also illustrated and is associated with the inner ring 14.Antifriction means 28, such as needle or ball bearings, a layer of antifriction material, such as "Teflon" or grease and/or oil, a sleeve bearing, and the like, is positioned between the input means 26 and the inner ring 14.

In the embodiment of Fig. 1 , the input means 26 comprises a generally cylindrical member 30 and a strut 32, the strut 32 being received in the member 30 and having a length in excess of the inner diameter of the member 30. The input means 26 is rotatable about an axis which coincides with the axes of the rings 12 and 14.

When so assembled, the member 30 becomes distorted to an oval configuration. Alternatively, the input means 26A could be an oval solid member body 34 as illustrated in Fig. 3.

Additionally, the input means 26B could be a pair of rollers 36, 36 connected by a strut 38 rotatable about its center, the rollers having a diameter less than that of the inner race and engaging the interior of the inner race, as is illustrated in Fig. 4.

In Figs. 3 and 4, like reference numbers are used to refer to like parts of Figs. 1 and 2.

Figs. 5 and 6 illustrate other input members 26C and 26D, respectively, which can be used to distort the inner ring 30 of the device.

The input member 26C of Fig. 5 comprises a split assembly of a first part 40 and a second part 42 with springs 44 urging the parts away from each other, thus forming a generally oval configuration. The spring force determines the degree of ovalness of the assembly.

The input member 26D of Fig. 6 is generally similar to that of Fig. 5 and comprises a split assembly of a first part 46 and a second part 48, the parts being urged apart by a hydraulic or pneumatic means comprising cylinders 50 in the part 46 with pistons 52 connected to the part 48.

Hydraulic or pneumatic fluid is supplied to the cylinders 50 from a source 54; the ovalness of the input means 26D can thus be controlled.

When the input means 26 (or 26A, 26B, 26C, 26D) is assembled in the inner ring 14, the inner ring becomes distorted from cylindrical configuration to oval configuration, causing some of the sprags 1 6 to change their angularity with respect to the inner race or ring 1 4. The driving sprags are angled greater than the angle of the non-driving sprags.

When the input means 26 in the Fig. 1 embodiment (and in the other embodiments of Figs. 3 to 6 using a central input means which distorts the inner ring of the device) is rotated, there is a sequential changing of the sprag or cam angle with the outer and inner rings 12 and 14.

The reaction of the cams causes rotation of one or more selected output members when at least one element is held stationary as a reaction member.

The output member can be the outer ring 12, the inner ring 14 and the cage 1 8 and combinations thereof. For example, rotation of the input member 26 in the Fig. 1 structure in either clockwise or counterclockwise direction (as viewed in the drawing) when the outer ring 12 is held stationary will produce rotation of the inner ring 14 and the cage 18 both in a counterclockwise direction at rotational rates which are different from each other and from that of the input means 26. When the cage 1 8 is held stationary and the input member is rotated, the inner ring 14 will rotate in a counterclockwise direction while the outer ring 12 will rotate in a clockwise direction. The rates of rotation of the inner and outer rings, as well as the direction of rotation, will be different. The rates of rotation will also be different from that of the input means.The drive ratios between the input and output members and between multiple output members is dependent upon the member of cams or sprags drivingly engaging the races and the physical size of the drive device itself.

Attention is invited to Fig. 7 showing a drive device 60 with an input member 62 which distorts the ou.ter ring 64 thereof. The device also comprises an inner ring 66, a plurality of cams or sprags 68 between the rings 64 and 66, a cage 70 with openings 72 to space the sprags or cams 68 and a spring means 74. In addition, antifriction means 76, such as needle or ball bearings, a layer of antifriction material such as "Teflon" or grease and/or oil, a sleeve bearing, and the like is positioned between the input member 62 and the outer ring 64. The input member 62 comprises a generally circular member with an oval interior configuration and is rotated about an axis which coincides with the axes of the rings 64 and 66.

When the parts are assembled, the ring 64 becomes distorted to an oval configuration generally matching the interior configuration of the input member. Upon rotation of the input member 62, there is a sequential changing of the angle of cams with the inner and outer rings 66 and 64. The reaction of the driving cams causes rotation of one or more selected output members when at least one element is held stationary as the reaction member. The output member can be the outer ring 64, the inner ring 66, and the cage 70 and combination thereof.

Figs. 8 and 9 illustrate a single rotor version of this invention which comprises an input shaft 1 50 and an output shaft 152, the latter being journaled in spaced bearing 1 54, 1 54 in a housing member 1 56 while the former is journaled in a bearing 1 58 in a housing cover 1 60 and a bearing 1 62 supported in the output shaft 1 52. The speedchanging mechanism 1 64 comprises an input member 1 66 which is generally oval in shape received in a rolier bearing 1 68 in turn surrounded by sprags 1 72 positioned between the output member 170 in the shape of a cup and surrounded by member 170 and an outer race 174. The output member 1 70 becomes distorted by rotation of the input member 1 66 and because of the reaction of the sprags 172, it will rotate at a different speed than that of the shaft 1 50. The output member 1 70 is bolted by bolts 1 76 to a flange 1 78 of the output shaft 1 52. The sprags are axially retained by a ring 1 80 as illustrated.

Claims

1. In a rotary drive device providing at least one unidirectional output which is independent of the direction of rotation of the input, the improvement comprising: a generally cylindrical outer ring a generally cylindrical inner ring; a plurality of cams or sprags between said rings; said cams or sprags being adapted to progressively engage and drivingly connect said rings; and input means to sequentially and progressively drivingly engage and disengage at least two of said cams or sprags with said rings to provide a driving connection therebetween; said last-named means being rotatable about an axis common with said rings and being constructed and arranged so as to progressively distort at least one of the rings from a cylindrical to a generally oval configuration.

2. In a rotary drive device as recited in Claim 1 wherein said last-named means is rotatable about an axis which coincides with the major axis of said cylindrical inner and outer rings.

3. In a rotary drive device as recited in Claim 1 wherein all members are rotatable about a common axis.

4. In a rotary drive device as recited in Claim 1 further comprising antifriction means between one of said rings and said input means permitting efficient relative movement therebetween.

4. A rotary drive device as recited in Claim 1 further containing at least one cage (18, 70) between said rings, said cage having openings (20, 72) therein to receive and space said cams or sprags.

5. A rotary drive device as recited in Claim 2 in which said input means comprises a strut (32, 38) having a length such as to distort said inner ring from cylindrical to oval configuration.

6. A rotary drive device as recited in Claim 5 wherein the strut means is a spring (44).

7. A rotary drive device as recited in Claim 5 wherein the length of the strut means (50, 52) is responsive to hydraulic pressure.

8. A rotary drive device as recited in Claim 5 in which the number of cams or sprags which engage said rings is dependent on the length of said strut means (46, 48) and further comprising means (50, 52) to vary the length of said strut means.

9. A rotary drive device as recited in Claim 1 wherein said input means causes a sequential and progressive wobble action of all sprags at least once per revolution of an input.

10. A rotary drive device substantially as herein described with reference to the accompanying drawings.

New Claims or Amendments to Claims filed on 12 May 1980.

Superseded claims 4 to 10.

New or Amended Claims:

5. In a rotary drive device as recited in Claim 4 further comprising antifriction means between said inner ring and said input member.

6. In a rotary drive device as recited in Claim 4 further comprising antifriction means between said outer ring and said input means.

7. In a rotary drive device as recited in Claim 1 further containing at least one cage between said rings, said cage having openings therein to receive and space said cams or sprags.

8. In a rotary drive device as recited in Claim 2 in which said last-named means comprises a strut means having a length such as to distort said inner ring from cylindrical to oval configuration.

9. In a rotary drive device as recited in Claim 8 wherein the strut means is a spring.

10. In a rotary drive device as recited in Claim 8 wherein the length of the strut means is responsive to hydraulic pressure.

11. In a rotary drive device as recited in Claim 8 in which the number of cams or sprags which engage said rings is dependent on the length of said strut means and further comprising means to vary the length of said strut means.

12. In a rotary drive device as recited in Claim 1 wherein said last-named means causes a sequential and progressive wobble action of all sprags at least once per revoiution of an input member.

13. A rotary drive device substantially as herein described with reference to the accompanying drawings.