WO1993011373A1

WO1993011373A1 - Improvements in helical, bevel and worm gear arrangements

Info

Publication number: WO1993011373A1
Application number: PCT/US1991/008848
Authority: WO
Inventors: Rudolf Richard Castens
Original assignee: Hybo Science, Inc.
Priority date: 1991-11-25
Filing date: 1991-11-25
Publication date: 1993-06-10
Also published as: CN1072250A

Abstract

The invention is comprised of first (10, 60, 110) and second gear members forming a gear pair, one of which is connected to an input shaft (11, 61, 111), the other of which is connected to an output shaft, such that rotational energy from the input shaft (11, 61, 111) is transferred through the respective gear members to the output shaft. Either the first gear member, the second gear member, or both, is manufactured in two parts, an inner member (12, 62, 112) and an outer member (22, 72, 122), the inner member (12, 62, 112) connected to the respective input (12, 62, 112) or output member (22, 72, 122), the outer member (22, 72, 122) defining the gear teeth (13, 63, 126). The inner member (12, 62, 112) defines a subderivative hyperboloidal inner race surface of revolution (14, 64, 114) about the axis of rotation of the gear member (10, 60, 110). The outer member (22, 72, 122) defines a superderivative hyperboloidal outer race surface of revolution (24, 74, 144) about the axis of rotation of the gear member (10, 60, 110). The inner and outer race surfaces are disposed in confronting relationship and define an annular circumferential volume therebetween separating the inner and the outer members. A plurality of thrust transmitting cylindrical rollers (28, 78, 128) are disposed in said volume.

Description

IMPROVEMENTS IN HELICAL, BEVEL AMD WORM GEAR ARRANGEMENTS BACKGROUND OF THE INVENTION

1. Field of the Invention This invention relates generally to torque transmitting couplings, and, specifically, relates to geared couplings of the helical, bevel and worm gear variety which incorporate a self-aligning unidirectional feature.

2. Description of the Prior Art Helical gears, bevel gears and worm gears are widely used. In some instances, it is desired that torque be transmitted between a first gear member and a second gear member of a gear arrangement with respect to one direction of relative rotation of said gear members yet to permit freewheeling, or no torque transfer, with respect to the opposite direction of rotation of the gear members, and hence of the inputs to the gear members. However, efforts to provide such a unidirectional rotational relationship between the gear members have required elaborate adjunct components incorporating many moving parts, unnecessarily increasing the friction losses, wear factor and weight of the equipment in which the helical, bevel or worm gear arrangement is incorporated. A particular example of a widely used and unnecessarily complicated arrangement is the planetary gear unit used in most automobile transmissions. It would be advantageous to have such a gear arrangement which is compact, self-contained and self- aligning without the necessity of extraneous equipment. SUMMARY OF THE INVENTION To this end, I have invented a novel arrangement of helical gear couplings and input/output shafts where torque is transferred through the gear members from the input to the output shaft for one direction of relative rotation thereof, yet the input shaft is decoupled from the output shaft for relative rotation of the shafts in the opposite direction. In addition, by incorporating the unidirectional clutch feature integrally within one or both of the gear members of the gear arrangement in a particular orientation, I have been able to utilize the axial forces generated in gear arrangements of the helical, bevel or worm type to maintain the unidirectional clutch arrangement in a self-aligned, or positively engaged, state. The invention is comprised of first and second gear members forming a gear pair, one of which is connected to an input shaft, the other of which is connected to an output shaft, such that rotational energy from the input shaft is transferred through the respective gear members to the output shaft. Either the first gear member, which is connected to the input shaft, the second gear member, which is connected to the output shaft, or both the first and second gear members, is manufactured in two parts, an inner member and an outer member, the inner member connected to the respective input or output shaft, the outer member defining the gear teeth. The inner member defines a subderivative hyperboloidal inner race surface of revolution about the axis of rotation of the gear member and also defines a first annular shoulder near a first, or larger diameter, end of the inner race surface. The outer member defines a superderivative hyperboloidal outer race surface of revolution about the axis of rotation of the gear member, and may or may not include an annular shoulder connected to one end of the outer race surface. The inner and outer race surfaces are disposed in confronting relationship and define an annular circumferential volume therebetween separating the inner and the outer members. A plurality of thrust transmitting cylindrical rollers are disposed in said volume, all similarly inclined with respect to radial planes. Each roller makes line contact with the inner race surface along a generator of that surface, and also makes line contact with the outer race surface along a generator of the outer race surface. The rollers are supported axially by the first shoulder connected to the inner race surface. Alternatively, the first shoulder may be connected to the outer race surface at a first, or large diameter, end of the outer race surface. A bearing means such as a thrust washer may be interposed between first ends of the rollers and the first shoulder to facilitate sliding movement of the rollers with respect to the shoulder. The arrangement described hereinabove comprises a unidirectional type clutch of the hyperboloidal type incorporated within a gear member, which transmits torque between the inner and outer members with respect to relative rotation of the input or output shaft, to which the inner member is connected, and the outer member in a first direction, yet which permits freewheeling thereof with respect to relative rotation in the opposite direction. Helical, bevel and wormtype gear arrangements are unique in that, due to the tapered or curving gear teeth, a force is directed along the axis of rotation of the respective gear members when the gear members rotate. Because the inner and outer members of the clutch tend to move apart during freewheeling, thereby increasing the distance between the inner and outer race surfaces, the inner and outer race surfaces are arranged so as to take advantage of these axial forces to bias the outer member toward the inner member during freewheeling to thereby maintain the rollers in positive engagement with the inner and outer race surfaces. By "positive" engagement is meant that the cylindrical rollers each are disposed in line contact with the inner race surface along generators of that surface and, additionally, the cylindrical thrust transmitting rollers are in line contact with the outer race surface along generators of that surface. It is an object of the instant invention to provide a helical, bevel or worm gear assembly where rotational energy from the input shaft is transf rred to the output shaft for a first direction of relative rotation of the shafts, yet the output shaft is decoupled from the input shaft for relative rotation thereof in the opposite direction. It is also an object of the present invention to provide a simple, compact and efficient gear arrangement of the helical, bevel or worm gear type which is self-aligning and hence maintains positive engagement between the inner and outer members of either or both gear members of the gear arrangement. In accordance with these and other objects which will become apparent hereinafter, the instant invention will now be described with particular reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a partial cross-sectional elevational view of a bevel gear incorporating the features of my invention. Figure 2 is a cross section taken along lines 2-2 of Figure 1. Figure 3 is a cross section taken along lines 3-3 of Figure l. Figure 4 is an elevational view of a worm member of a worm gear arrangement incorporating the features of my invention. Figure 5 is a_. cross section taken along lines 5-5 of Figure 4. Figure 6 is a cross section taken along lines 6-6 of Figure 4. Figure 7 is a partial cross-sectional elevational view of a helical gear member incorporating the features of my invention. Figure 8 is an exploded view of the helical gear shown in Figure 7. Figure 9 is a partial cross-sectional view of a helical gear constructed in accordance with my invention installed in a planetary gear housing. Figure 10 is a perspective view of a planetary gear housing employing planetary gear arrangements in accordance with my invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings. Figures 1 - 3 show a bevel gear 10 in accordance with my invention integrally connected to a machine-connectable shaft 11, such as by splines, threading, or the like, comprised of a first or inner member 12 rigidly connected to shaft 11, said inner member defining a subderivative hyperboloidal inner race surface of revolution 14 about the axis of rotation 20 of gear 10. First member 12 also defines a first annular shoulder 16 connected to a first end of inner race surface 14. First member 12 may also define a second annular shoulder connected to the inner race surface at a second end thereof. The second element of gear 10 is a second or outer member 22 circumferentially surrounding first member 12 and defining a superderivative hyperboloidal outer race surface of revolution 24 about axis 20 and defining an annular volume with inner race surface 14. Disposed in said annular volume are a plurality of thrust transmitting cylindrical rollers 28, all being similarly inclined with respect to radial planes. Each roller 28 makes line contact with inner race surface 14 along a generator of the inner race surface. Each roller 28 also makes line contact with outer race surface 24 along a generator of that outer race surface. Rollers 28 are supported axially by shoulders 16 and 18. Either shoulder 16 and/or shoulder 18 may be connected to outer member 22. Bearing means such as thrust transmitting annular washer 30 may be placed between first ends of rollers 28 and shoulder 16 to facilitate sliding movement of said rollers with respect to first shoulder 16 when first member 12 rotates with respect to second member 22. Likewise, a second bearing means such as annular thrust washer 34 may be disposed between second ends of rollers 28 and shoulder 18 to facilitate sliding movement of said rollers with respect to shoulder 18 during freewheeling. An oil seal 32 or other means for sealing may be provided between first and second members 12, 22 both at the second as well as the first end of gear 10 to prevent the departure of lubrication and the encroachment of contaminants. Snap rings 36 or other means for retaining first member 12 in association with second member 22 may also be provided near the first end of gear 10. Second member 22 has disposed about its outer periphery a plurality of slanted bevel gear teeth 13 adapted to mesh with corresponding teeth on a second bevel gear (not shown) . Due to the slanted orientation of teeth 13, a net axial force from right to left in Figure 2 is imposed on secondmember 22 during both directions of relative rotation of the bevel gear pair. This net axial force tends to maintain inner and outer race surfaces 14, 24 in positive engagement with rollers 28 during freewheeling of the first member 12 relative to second member 22, thereby eliminating backlash or slippage when switching from rotation of shaft 11, and hence first member 12, in the counter-clockwise direction when viewed from the right in Figure 1 to clockwise rotation of shaft 11; and hence first member 12, when viewed from the right in Figure 2. This shift in direction is between the torque transmitting mode and the freewheeling mode of the unidirectional bevel gear arrangement of my invention. It is also contemplated to provide lubrication to the rollers 28. To this end, I have provided a lubrication inlet bore 42 in metering bolt 40 to fluidly communicate a source of lubricant (not shown) with an inner chamber 43 of first member 12. Lubricant may thereafter pass through radial bore or bores 44 communicating chamber 43 with the annular volume between inner and outer race surfaces 14, 24. Lubrication may exit said annular volume through channel 46 and pass through radial bore or bores 48 and exit through axial bore 50 defined by shaft 11. Alternative or substitute lubricating arrangements may be provided as desired. A mounting or connecting means such as bolt 51 may be employed, in which case a corresponding axial channel 52 should be provided for passage of lubricant therefrom. However, the specific lubrication structure disclosed herein is not intended to limit the scope of my invention to that shown. Referring now to Figures 4 - 6, there is shown a worm gear 60 of a worm gear assembly integrally connected to a machine-connectable shaft 61. Worm gear 60 is comprised of a first, or inner, member 62 rigidly connected to shaft 61. First member 62 defines a subderivative hyperboloidal inner race surface of revolution 64 about the axis of revolution 70 of gear 60. First member 62 may also define a first annular shoulder 66 connected to inner race surface 64 near the first, or large diameter end, of member 62. First member 62 may also define a second annular shoulder^' 68 nearest the second, or small diameter, end thereof. Circumferentially disposed for unidirectional rotation about first member 62 is second, or outer, member 72 which defines a superderivative hyperboloidal outer race surface of revolution 74 about axis 70. Surfaces 64 and 74 define an annular volume therebetween in which is disposed a plurality of cylindrical thrust transmitting rollers 78. All said rollers 78 are similarly inclined with respect to radial planes. Each roller 78 makes line contact with inner race surface 64 along a generator of that surface. Each roller 78 also makes line contact with outer race surface 74 along a generator of the outer race surface. Said rollers are supported axially by shoulders 66, 68. Preferably, a first bearing means such as annular thrust washer 80 is disposed at the interface of first ends of rollers 78 and shoulder 66 to facilitate sliding movement of said rollers with respect to said shoulder 66 during the freewheeling mode. Likewise, a second bearing means such as thrust washer 84 may be provided at the interface of second ends of rollers 78 and shoulder 68 to facilitate sliding movement of rollers 78 with respect to shoulder 68. Sealing means such as oil seal 82 may be provided between first and second members 62, 72 to prevent the escape of lubricant and the entrance of contaminants. Lubrication means may be provided, such as lubricant inlet bore 92 in metering bolt 90 to fluidly communicate a source of lubricant with an inner chamber 93, which in turn is fluidly communicated via bore 94 with the annular volume between surfaces 64, 74. Lubricant is thereupon permitted to flow freely between rollers 78, and by centrifugal force, is carried from the second end to the first end of inner and outer members 62, 72 due to the diverging configuration of the sloping race surfaces 64, 74. Lubricant is carried via channel 96 and radial bore or bores 98 to lubrication outlet bore 100 in shaft 61. A connecting means such as bolt 101 may be employed to connect gear 60 to a machine element, in which case an axial bore 102 corresponding to axial bore 100 should be provided. As for the embodiment of Figures 1 - 3, the lubrication structure is purely exemplary and not intended to limit the scope of my invention. Any other expedient for providing lubrication to said rollers is contemplated. Figures 7 - 8 show a helical gear assembly 110 integrally connected to a shaft 111, which in turn is connectible to a machine element (not shown) . Gear 110 is comprised of a first, or inner, member rigidly connected to shaft 111 and defining, a subderivative hyperboloidal inner race surface of revolution 114 about axis of rotation 120 of gear 110. First member 112 defines an annular shoulder 116 connected thereto at a first, or large diameter, end of inner race surface 114, which coincides with the first, or large diameter, end of inner member 112. Gear 110 also comprises a second, or outer, member 122 disposed circumferentially about first member 112, said second member 122 defining a superderivative hyperboloidal outer race surface of revolution 124 about axis 120, surfaces 114 and 124 being in confronting relationship to one another and defining an annular volume therebetween. First member 112 may also have a second annular shoulder 118 connected thereto opposite the first annular shoulder 116, second annular shoulder 118 being connected to inner race surface 114 near the second, or small diameter, end of first member 112. Second member 122 has connected, to its outer peripheral surface helical gear teeth 126 adapted to mesh with a corresponding set of gear teeth (not shown) o a corresponding gear. Aplurality of thrust transmitting rollers 128 are disposed in said annular volume between inner and outer race surfaces 114, 124, each of said rollers 128 being disposed at an angle with respect to radial planes through axis 120 such that each roller 128 makes line contact with inner race surface 114 along a generator of that surface, and each roller 128 also makes line contact with outer race surface 124 along generators of that surface 124. Shoulders 116, 118 are adapted to support rollers 128 axially thereof. A first bearing means such as first annular thrust washer 130 may be disposed between first ends of rollers 128 and shoulder 116 so as to facilitate sliding movement of rollers 128 relative to shoulder 116 when second member 122 is rotated in the freewheeling mode relative to first member 112. Likewise, a second bearing means such as annular thrust washer 134 may be disposed between second ends of rollers 128 and second shoulder 118 to facilitate the aforementioned sliding movement. In the preferred embodiment, gear 110 is provided with a lubrication arrangement to provide a continuous flow, as needed, of lubricant to rollers 128 to assure smooth performance thereof. To this end, a lubrication inlet channel 142 is disposed centrally through bolt 140, fluidly communicating a source of lubricant (not shown) with a lubrication chamber 143. Chamber 143 is in turn, fluidly communicated with the annular volume between inner and outer race surfaces 114, 124, respectively, via bore 144 disposed radially within first member 112. A plurality of such bores 144 may be utilized to increase flow volume of lubricant. Said lubricant flows via centrifugal force from the second end nearest second thrust washer 134 toward the first end nearest shoulder 116 of first and second members 112, 122, and exits the annular volume via circumferential passageway 146, and in turn is permitted to flow through radial bore(s) 148, and to exit gear 110 via lubricant outlet channel 150 disposed, preferably centrally, in shaft 111. It is to be understood that the lubrication structure set forth for the invention of Figures 7 through 9 may also be varied to suit the circumstances. Therefore, the particular arrangement shown is deemed exemplary and is not intended to limit the scope of this disclosure. Figures 9 - 10 show an application of gear 110 to a planetary gear housing 160 used in the transmission of virtually all internal combustion powered vehicles. In this way, a substantial reduction in weight and inertia related drag losses may be eliminated from the planetary gear system as presently available by replacement of the planetary gears and freewheel, which is located remotely of the planetary gears presently used, with the planetary gears 110 of Figures 7 - 8. Gear 110 may be affixed to planetary gear member 160 by any known expedient such as by press-fitting shaft ill through a corresponding aperture 161 in planetary gear member 160. Gear 110 is then connected to member 160 via any suitable connector such as threaded bolt 162. If the lubrication structure set forth in the drawings is utilized in the arrangement shown in Figure 9, lubrication outlet channel 150 should be fluidly communicated with the interior of the transmission casing via bore 164 defined by bolt 162. A principle benefit of utilizing a helical, bevel or worm gear arrangement comprised of two parts, an inner hyperboloidal race member and an outer hyperboloidal race member with cylindrical thrust transmitting rollers positioned therebetween in line contact with both inner and outer race surfaces, is that the axial forces, that is, forces directed along the axis of rotation of the gear, generated in such gears actually urge the inner and outer race surfaces to maintain line contact with the rollers so as to minimize, or eliminate, any backlash or slippage between the inner and outer race members when the outer race member is switched from freewheeling relative to the inner race member to transmitting torque to or from the inner race member. Because the sloping inner and outer race surfaces, together with the rollers in line contact therewith, form a unidirectional clutch of the hyperboloidal type, the structure and performance of which is fully set forth in my copending United States Patent Application Serial No. 07/418,795, filed October 3, 1989, the disclosure of which is incorporated by reference herein as though fully set forth herein, when the inner race member is freewheeled relative to the outer race member, the inner and outer race members tend to separate from one another in the axial direction during freewheeling, thus tending to increase the distance between the inner and outer race surfaces, because of tangential frictional forces generated between the rollers and the surfaces in the freewheeling condition. The axial forces generated by the helical, bevel and worm gear arrangements commonly known in the art can be used to counteract these separation forces generated in the clutch during freewheeling. The orientation of the inner and outer race surfaces of the gear elements shown in Figures 2, 5 and 7 should be selected such that the axial forces arising out of operation of the outer race member in association with a corresponding gear element tends to move the outer race member axially toward the first, or large diameter end, of the inner race member. For the gear unit shown in Figure 2, outer race member 22 would be urged to the left in the drawing by virtue of the angled orientation of the surface to which teeth 13 are connected to outer race member 22. For the embodiment of Figure 5, outer race member 72 would be moved to the right in the drawing, and the proper orientation of screw threads 63 adopted so as to give rise to a net axial force on outer race member 72 to the right in Figure 5 during freewheeling. Likewise, for the embodiment of Figure 7, because of the orientation of gear teeth 126 and the direction of rotation selected during which outer race member 122 will freewheel with respect to inner race member 112, a net axial force will act upon outer race member 122 during such freewheeling tending to move outer race member 122 to the right in Figure 7, thereby maintaining line contact between rollers 128 and inner and outer race surfaces 114, 124. In this way, the line contact between the rollers and race surfaces is not broken during freewheel, so that when the direction of relative rotation is reversed between inner and outer race members 112, 122 so as to cause locking, torque transmitting engagement between said inner and outer race members through the thrust transmitting rollers, no slippage will occur. Figure .10 shows a planetary gear housing 160 having connected thereto a plurality of planetary gear members 110 constructed in accordance with my invention. Planetary gears 110 are caused to rotate about a sun gear (not shown) in the well known manner. By providing unidirectional helical gears 110, the freewheel ordinarily used in association with housing 160 can be eliminated, thereby reducing the weight and size of the overall planetary gear unit. The instant invention has been shown and described herein in what is considered to be the most practical and preferred embodiment. It is recognized, however, that departures may be made therefrom within the scope of the invention and that obvious modifications will occur to a person skilled in the art.

Claims

What I Claim Is:

1. A gear pair including a first gear member, an input shaft connected to said first gear member, a second gear member, an output shaft connected to said second gear member, at least one of said first or second gear members being comprised of an inner member and an outer member, said inner member being connected to said input or output shaft, said outer member having gear teeth disposed about the periphery thereof, said inner member defining about its outer periphery a subderivative hyperboloidal inner race surface of revolution about the axis of rotation of said gear member, said outer member defining about its inner periphery a superderivative hyperboloidal outer race surface of revolution about the axis of rotation of said gear member, said inner and outer race surfaces defining an annular volume therebetween, a plurality of cylindrical thrust transmitting rollers disposed in said volume, all said rollers being similarly inclined with respect to radial planes and making line contact with the inner race surface along a generator of the inner race surface and line contact with the outer race surface along a generator of the outer race surface, a first shoulder member connected to the inner or outer race member near a first end of said inner or outer race surface, respectively, adapted to support the rollers axially thereof.

2. The gear pair of claim 1, wherein said gear members are bevel gears.

3. The gear pair of claim 1, wherein said gear members are helical gears.

4. The gear pair of claim 1, wherein the gear members are a worm and worm gear.

5. The gear pair of claim 1, further comprising a means at the interface of first ends of said rollers and said first shoulder for facilitating sliding movement of said rollers with respect to said first shoulder when said outer member is rotated relative to said inner member.

6. The gear pair of claim 5, further comprising a second shoulder connected to either the inner or outer member adapted to support the rollers axially thereof opposite said first shoulder, and a second means at the interface of second ends of said rollers and said second shoulder for facilitating sliding movement of said rollers with respect to said second shoulder when said outer member is rotated relative to said inner member.

7. The gear pair of claim 1, further comprising means for lubricating the rollers during operation of the gear pair.

8. The gear pair of claim 5, further comprising means for lubricating said rollers.

9. A gear member comprised of: an inner member connectible for rotation to a machine component; an outer member defining gear teeth about its outer periphery concentrically disposed about said inner member; said inner and outer members being connected by a unidirectional clutch/bearing/freewheel whereby torque is transmitted between said inner and outer members for attempted relative rotation thereof in a first direction, yet said inner member is permitted to freewheel with respect to relative rotation thereof in the opposite direction.

10. The gear member of claim 9, wherein said unidirectional clutch/bearing/freewheel is a unidirectional clutch of the hyperboloidal type.