CA1077305A - Traction controlled in-line transmission - Google Patents
Traction controlled in-line transmissionInfo
- Publication number
- CA1077305A CA1077305A CA299,884A CA299884A CA1077305A CA 1077305 A CA1077305 A CA 1077305A CA 299884 A CA299884 A CA 299884A CA 1077305 A CA1077305 A CA 1077305A
- Authority
- CA
- Canada
- Prior art keywords
- drive
- roller
- rollers
- traction
- input
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H37/00—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00
- F16H37/02—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings
- F16H37/06—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts
- F16H37/08—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing
- F16H37/0833—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing with arrangements for dividing torque between two or more intermediate shafts, i.e. with two or more internal power paths
- F16H37/084—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing with arrangements for dividing torque between two or more intermediate shafts, i.e. with two or more internal power paths at least one power path being a continuously variable transmission, i.e. CVT
- F16H37/0853—CVT using friction between rotary members having a first member of uniform effective diameter cooperating with different parts of a second member
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H15/00—Gearings for conveying rotary motion with variable gear ratio, or for reversing rotary motion, by friction between rotary members
- F16H15/02—Gearings for conveying rotary motion with variable gear ratio, or for reversing rotary motion, by friction between rotary members without members having orbital motion
- F16H15/04—Gearings providing a continuous range of gear ratios
- F16H15/06—Gearings providing a continuous range of gear ratios in which a member A of uniform effective diameter mounted on a shaft may co-operate with different parts of a member B
- F16H15/16—Gearings providing a continuous range of gear ratios in which a member A of uniform effective diameter mounted on a shaft may co-operate with different parts of a member B in which the member B has a conical friction surface
- F16H15/18—Gearings providing a continuous range of gear ratios in which a member A of uniform effective diameter mounted on a shaft may co-operate with different parts of a member B in which the member B has a conical friction surface externally
- F16H15/20—Gearings providing a continuous range of gear ratios in which a member A of uniform effective diameter mounted on a shaft may co-operate with different parts of a member B in which the member B has a conical friction surface externally co-operating with the outer rim of the member A, which is perpendicular or nearly perpendicular to the friction surface of the member B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H37/00—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00
- F16H37/02—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings
- F16H37/06—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts
- F16H37/08—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing
- F16H37/0833—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing with arrangements for dividing torque between two or more intermediate shafts, i.e. with two or more internal power paths
- F16H37/084—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing with arrangements for dividing torque between two or more intermediate shafts, i.e. with two or more internal power paths at least one power path being a continuously variable transmission, i.e. CVT
- F16H2037/088—Power split variators with summing differentials, with the input of the CVT connected or connectable to the input shaft
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Friction Gearing (AREA)
- Transmission Devices (AREA)
- Structure Of Transmissions (AREA)
Abstract
A B S T R A C T
A variable diameter traction roller is connected in line with high torque transmitting gearing of the planetary type to control the over-all transmission drive ratio through an axially shiftable, driven traction roller. The driven traction roller is mounted on a pivotally displaceable bracket through which a tension device exerts a variable contact force and the pitch line angle between traction rollers is varied by a limited amount.
A variable diameter traction roller is connected in line with high torque transmitting gearing of the planetary type to control the over-all transmission drive ratio through an axially shiftable, driven traction roller. The driven traction roller is mounted on a pivotally displaceable bracket through which a tension device exerts a variable contact force and the pitch line angle between traction rollers is varied by a limited amount.
Description
7'~05 'rilIS INVENTION relates to variable speed transmissions.
In Canadian Application Serial No. 284,971 filed August 18, 1977, the transmission disclosed featured a traction drive assembly through which a small fraction of the total torque transmitted by the transmission is utilised to vary and establish the overall transmission drive ratio in a practical and efficient manner by providing a favourable relationship between the drive ratio and the contact pressure in the traction drive assembly. The traction drive assembly is positioned in laterally spaced relationship to the transmission gearing and includes a driven traction roller axially shiftable along a fixed path parallel to the common rotational axis for the transmission input and output shafts. The other traction roller of variable diameter is mounted on a pivotally displaceablè
bracket for limited corrective displacement during axial shift of the driven roller engaged therewith to vary the drive ratio.
~ According to the present invention, there is provided a : change speed transmission, comprising input and output members, a power transmitting gear arrangement drivingly interconnecting said input and output members for establishing a relatively high torque power path therebetween, a low torque biasing gear - arrangement drivingly connected between the input member and the power transmitting gear arrangement for establishing a drive ratio between the input and output members, and a variable traction drive driven by the input bm/p~
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7tî'305 member for controlling, by means of the torque biasing gear arrangement, said drive ratio, said traction drive including a traction roller rotatable about a fixed axis common to the input and output members~
In the preferred embodiment the traction drive includes a roller, whose diameter varies along its length driven by an input shaft about the rotational axis common to the input and an output shaft. A driven traction roller is mounted on a pivotal bracket and is axially shiftable along its spLlne shaft to change the transmission drive ratio. Contact pre~sure between the rollers is changed as a function of the driven roller position and the pitch line curvatures of the roller~
at the contact zone. The contact pressure is thereby varied in an optimum manner characterised by a minimum pressure in the neutral position of the driven roller as predetermined by the drive relation~hips in the gearing which is axially aligned with the variable diameter tr~ction rollerO As an alternative, the axially shiftable roller could be rotatable about a fixed axis common with the input and output shafts ; 20 while the variable diameter roller i~ mounted at an angle thereto on the bracket. In the latter arrangement, a plurality of variable diameter rollers could be mounted by a plurality of brackets for drive engagement with the axially shiftable roller in order to distribute the torque load and thereby increase the load capacity of the transmission.
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~,~ ' `' ' ` ' ' Power transmis~ion through the gearing may be interrupted by release of a hydrosta-tic brake holding a floating carrier for a gear train interconnecting orbit gears in the high torque transmitting gear assembly of the transmission~
The invention will be further described with reference to the accompanying drawings, in which:-Figure 1 is a somewhat simplified and partially schematic side elevational view of an embodiment of transmission in accordance with the present inven-tion, Figures 2, 3 and 4 are enlarged partial sectional views of the gearing taken substantially on planes indicated by section lines 2-2, 3-3 and 4-4 in Figure l;
: Figure 5 is an ~nlarged partial sectional view of the . traction drive assembly taken substantially through a plane `~ 15 indicated by section line 5-5 in Figure 1:
Figure 6 is a graph showing various operational relationships associated with the transmission of Figure 1.
Referring now to Figure 1 in particular, the transmission 12 includes an input shaft 16 and an axially aligned output shaft 18. The input shaft i5 directly connected to an infinitely variable traction drive assembly generally referred to by réference numeral 42 through which selection of the over-all transmission drive ratio is effected. A power transmitting gear assembly 40 drivingly interconnects the input`and output shafts while torque bias 7';'~)5 control means 44 drivingly interconnects the variable traction drive assembly 42 with the powcr transmitting gear assembly 40.
The torque bias control means 44 is arranged to reduce the ordinarily expected load and power requirements imposed on the variable traction drive assembly in performing its drive ratio changing function for the over-all tran~mission.
As more clearly seen in Figures 1, 3 and 4, the power transmitting gear assembly 40 includes a differential planetary gear set 46 formed by a sun gear 48 fixed to the inner end of the input shaft 16. The sun gear 48 is in constant mesh with planet gears 50 rotatably mounted on a carrier 52. The planet gears 50 also mesh with an internal orbit gear 54 having train external gear teeth 56 enmeshed with a floating gear/comprising intermeshing gears 58, 60 drivingly connecting the orbit gear 54 to orbit gear 64 associated with a power path combining planetary gear set 66. The gear train includes intermeshing gears 58 and 60. The parallel axes of the gears in this year . train are rotatable on a carrier. 62 adapted to be retarded against rotation by a hydrostatic braking device 74 of any well-known type connected to a cloced fluid control circuit 22.
The gear set 66 includes planet gears 68 in constant mesh with .~ the orbit gear 64 and rotatably mounted on a carrier 70 fixedto th~ output shaft 18. The planet gears 68 are also in mesh with a sun ~ear 72 that is fixed to the carrier 52 of the : 25 differential gear set 460 ., !
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. ' . ' ' ~ ~ ' ' ' :
1()773~)5 It will be apparent that the :input ~haft 16 will transmit torque through the gear set 46 at a drive ratio dependent on the rotational ~peed of the carrier 52 relative : to the sun gear 48. The carrier 52 is, therefore, rokated at a lower speed than the input sha~t to enable transmission of high torque through gear set 4~ to the orbit gear 54 under control of a relativ~ly low torque drive throu~h the variable traction drive assembly 42. The power path through which low torque is transmitted to the carriex 52 ~or drive rat:Lo control purposes terminates at the sun gear 72 of gear set 66 to ~ which high torque is transmitted from orbit gear 54 through : the gear train formed by gears 58, 60 and 61 ~hen the floating gear carrier 62 is held stationary by the hydrostatic : brake 74. Manual or override control over the transmission: 15 may be exercised through the hydrostatic brake by means of : .
its fluid control circuit 22. A neutral and drive control valve assembly 24 may accordingly be a~sociated with the fluid circuit to selectively restrict 10w therein. A spring or automatically biased torque control valve 26 may also be connected in parallel with the control valve assembly 24.
. Shock protection is provided by an accumulator 28.
A pressure sensor 29 connected to the fluid circuit will be ~ effective to monitor the torque transmitted through the ; gearing and thereby supply a signal to an automatic control 30 for ~hanging the spring tension of the device 152 in order . to compens~te for abrupt increa~es in torque loading on the .y - 6 -~. .
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transmission. Other control arrangements may, of course, be utilised for the brake device 74. A parking brake element 80 i5 al~o provided on the c)utput shaft 18.
It will be apparent that a suitable housiny will be provided for the transmission hereinbefore described, constituting the sta~ionary frame for the gearing. The housing frame supports a fixed pivot 92 about which a slide bracket 120 is pivotally displaceable in a pivotal plane intersecting the common rotational axis of the input and output shafts. The slide bracket 120 rotatably mounts an ; elongated position control screw 124 by means of spaced bearings carried by the bracket 120. The screw 124 is threadedly engaged with a carriage 112 as shown in Figures ; 1 and 5 for displacement of a traction roller element 110 axially along a shaft 118 to which it is splined. The shaft 118 is rotatably mounted on the bracket 120 by a bearing 90 for rotation about an axis parallel to that of the screw shaft 124. A suitable coupling joint 100 connects the spline shaft 118 to a gear 132 ~or transmitting a low control torque to the torque bias control means 40. Gear 132 and gear 134 with which it is enmeshed are fixed axes gears for transmitting the low torque to an orbit gear 136 associated with the torque bias control means 44. The orbit gear 136 is in constant mesh with planet gears 138 as shown in Figures
In Canadian Application Serial No. 284,971 filed August 18, 1977, the transmission disclosed featured a traction drive assembly through which a small fraction of the total torque transmitted by the transmission is utilised to vary and establish the overall transmission drive ratio in a practical and efficient manner by providing a favourable relationship between the drive ratio and the contact pressure in the traction drive assembly. The traction drive assembly is positioned in laterally spaced relationship to the transmission gearing and includes a driven traction roller axially shiftable along a fixed path parallel to the common rotational axis for the transmission input and output shafts. The other traction roller of variable diameter is mounted on a pivotally displaceablè
bracket for limited corrective displacement during axial shift of the driven roller engaged therewith to vary the drive ratio.
~ According to the present invention, there is provided a : change speed transmission, comprising input and output members, a power transmitting gear arrangement drivingly interconnecting said input and output members for establishing a relatively high torque power path therebetween, a low torque biasing gear - arrangement drivingly connected between the input member and the power transmitting gear arrangement for establishing a drive ratio between the input and output members, and a variable traction drive driven by the input bm/p~
. . ~ . . . .
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. .
.
~: -. .
7tî'305 member for controlling, by means of the torque biasing gear arrangement, said drive ratio, said traction drive including a traction roller rotatable about a fixed axis common to the input and output members~
In the preferred embodiment the traction drive includes a roller, whose diameter varies along its length driven by an input shaft about the rotational axis common to the input and an output shaft. A driven traction roller is mounted on a pivotal bracket and is axially shiftable along its spLlne shaft to change the transmission drive ratio. Contact pre~sure between the rollers is changed as a function of the driven roller position and the pitch line curvatures of the roller~
at the contact zone. The contact pressure is thereby varied in an optimum manner characterised by a minimum pressure in the neutral position of the driven roller as predetermined by the drive relation~hips in the gearing which is axially aligned with the variable diameter tr~ction rollerO As an alternative, the axially shiftable roller could be rotatable about a fixed axis common with the input and output shafts ; 20 while the variable diameter roller i~ mounted at an angle thereto on the bracket. In the latter arrangement, a plurality of variable diameter rollers could be mounted by a plurality of brackets for drive engagement with the axially shiftable roller in order to distribute the torque load and thereby increase the load capacity of the transmission.
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~,~ ' `' ' ` ' ' Power transmis~ion through the gearing may be interrupted by release of a hydrosta-tic brake holding a floating carrier for a gear train interconnecting orbit gears in the high torque transmitting gear assembly of the transmission~
The invention will be further described with reference to the accompanying drawings, in which:-Figure 1 is a somewhat simplified and partially schematic side elevational view of an embodiment of transmission in accordance with the present inven-tion, Figures 2, 3 and 4 are enlarged partial sectional views of the gearing taken substantially on planes indicated by section lines 2-2, 3-3 and 4-4 in Figure l;
: Figure 5 is an ~nlarged partial sectional view of the . traction drive assembly taken substantially through a plane `~ 15 indicated by section line 5-5 in Figure 1:
Figure 6 is a graph showing various operational relationships associated with the transmission of Figure 1.
Referring now to Figure 1 in particular, the transmission 12 includes an input shaft 16 and an axially aligned output shaft 18. The input shaft i5 directly connected to an infinitely variable traction drive assembly generally referred to by réference numeral 42 through which selection of the over-all transmission drive ratio is effected. A power transmitting gear assembly 40 drivingly interconnects the input`and output shafts while torque bias 7';'~)5 control means 44 drivingly interconnects the variable traction drive assembly 42 with the powcr transmitting gear assembly 40.
The torque bias control means 44 is arranged to reduce the ordinarily expected load and power requirements imposed on the variable traction drive assembly in performing its drive ratio changing function for the over-all tran~mission.
As more clearly seen in Figures 1, 3 and 4, the power transmitting gear assembly 40 includes a differential planetary gear set 46 formed by a sun gear 48 fixed to the inner end of the input shaft 16. The sun gear 48 is in constant mesh with planet gears 50 rotatably mounted on a carrier 52. The planet gears 50 also mesh with an internal orbit gear 54 having train external gear teeth 56 enmeshed with a floating gear/comprising intermeshing gears 58, 60 drivingly connecting the orbit gear 54 to orbit gear 64 associated with a power path combining planetary gear set 66. The gear train includes intermeshing gears 58 and 60. The parallel axes of the gears in this year . train are rotatable on a carrier. 62 adapted to be retarded against rotation by a hydrostatic braking device 74 of any well-known type connected to a cloced fluid control circuit 22.
The gear set 66 includes planet gears 68 in constant mesh with .~ the orbit gear 64 and rotatably mounted on a carrier 70 fixedto th~ output shaft 18. The planet gears 68 are also in mesh with a sun ~ear 72 that is fixed to the carrier 52 of the : 25 differential gear set 460 ., !
, .
. ' . ' ' ~ ~ ' ' ' :
1()773~)5 It will be apparent that the :input ~haft 16 will transmit torque through the gear set 46 at a drive ratio dependent on the rotational ~peed of the carrier 52 relative : to the sun gear 48. The carrier 52 is, therefore, rokated at a lower speed than the input sha~t to enable transmission of high torque through gear set 4~ to the orbit gear 54 under control of a relativ~ly low torque drive throu~h the variable traction drive assembly 42. The power path through which low torque is transmitted to the carriex 52 ~or drive rat:Lo control purposes terminates at the sun gear 72 of gear set 66 to ~ which high torque is transmitted from orbit gear 54 through : the gear train formed by gears 58, 60 and 61 ~hen the floating gear carrier 62 is held stationary by the hydrostatic : brake 74. Manual or override control over the transmission: 15 may be exercised through the hydrostatic brake by means of : .
its fluid control circuit 22. A neutral and drive control valve assembly 24 may accordingly be a~sociated with the fluid circuit to selectively restrict 10w therein. A spring or automatically biased torque control valve 26 may also be connected in parallel with the control valve assembly 24.
. Shock protection is provided by an accumulator 28.
A pressure sensor 29 connected to the fluid circuit will be ~ effective to monitor the torque transmitted through the ; gearing and thereby supply a signal to an automatic control 30 for ~hanging the spring tension of the device 152 in order . to compens~te for abrupt increa~es in torque loading on the .y - 6 -~. .
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transmission. Other control arrangements may, of course, be utilised for the brake device 74. A parking brake element 80 i5 al~o provided on the c)utput shaft 18.
It will be apparent that a suitable housiny will be provided for the transmission hereinbefore described, constituting the sta~ionary frame for the gearing. The housing frame supports a fixed pivot 92 about which a slide bracket 120 is pivotally displaceable in a pivotal plane intersecting the common rotational axis of the input and output shafts. The slide bracket 120 rotatably mounts an ; elongated position control screw 124 by means of spaced bearings carried by the bracket 120. The screw 124 is threadedly engaged with a carriage 112 as shown in Figures ; 1 and 5 for displacement of a traction roller element 110 axially along a shaft 118 to which it is splined. The shaft 118 is rotatably mounted on the bracket 120 by a bearing 90 for rotation about an axis parallel to that of the screw shaft 124. A suitable coupling joint 100 connects the spline shaft 118 to a gear 132 ~or transmitting a low control torque to the torque bias control means 40. Gear 132 and gear 134 with which it is enmeshed are fixed axes gears for transmitting the low torque to an orbit gear 136 associated with the torque bias control means 44. The orbit gear 136 is in constant mesh with planet gears 138 as shown in Figures
2~ 1 ahd 2, said planet gears being rotata~ly mounted on the same ` ' ' . ' ' '- '; ' ~ ' . .
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carrier 52 associated with the power transmitting gear assembly 40. A sun gear 140 fixed to the input shaft 16 meshes with the planet gear 13~.
The traction roller element 110 which is of substan-tially constant drive diameter is held in frictional drive en~agement with a variable cliameter traction drive element 94 fixed to thP input shaft for rotation therewith about ~he central rotational axis of the transmission. An adju~table tension device 152, such as that disclosed in my prior copending Application aforementioned, bears against the pivotal slide bracket 120 so as to establish the drive engaging pressure between the traction roller elements 110 and 94 at their zone of contact. The zone of co~tact is, of course, shifted by ; rotation of the screw shaft 124 so as to change the transmission - 15 drive ratio and will at the same time change the leverage ratio throuyh which the tension device 152 exerts its force at the zone of contact. Therefore, the contact force will vary for each position of the roller element 110 in accordance with some non-linear function as depicted by curve 168 in Figure 6. The geometry of the arrangement described is such ; that the minimum point 170 on the curve 168 coincides with the neutral condition of the transmission corresponding to a zero drive ratio, the drive ratio being reflected on the ordinate 162. The drive ratio is proportional to the displacement of the roller element 110 as depicted by the ~ 8 _ :, , ' ~ .
7~73(~
straigh~ line curve 158 plotted again~t the roller e1.ement position on the absci3~a 160.
The roller element 110 i~ sh.ifted along shaft 118 between one limit position clS shown in Figure 1 at which the roller elements are of equal diameter as shown by way of example to an opposite limit: po~ition at which the di~neter of roller element 94 is sub~tantially greater than that of roller element 110 in order to vary the dri~e ratio in the drive a~sembly 42 and thereby vary the over-all transmi~ion drive ratio as aforementioned. Ordinarily the roller elements engage each othex along a straight or constant coniaal pitch line corresponding to the pitch angle between the rotational axes of the input shaft 16 and the roller spline ~haft 118.
In order to meet varying torque requirements, the pitch line along which the r~ller elements engage each other iq varied by providing the roller element 94 with a variable pitch curvature 154. The curvature 154 may be de~igned to effect a change in contact pressure as a.function of the transmis~ion drive ratio. A crown curvature 1.56 al~o deviating from the basic pitch angle i~ provided for the roller element 110.
A ~mall amount of pivotal displacement ~f the roller element 110 ~bo~t pivot 92 occur~ during movement of the roller element ~ etween it~ limit position3 for corrective variation in the basi~ pitch ~ngle from-which.the roller curvature~ 154 and 156 ~viate,The curvature~ 154 and 156 are theoretically - g _ . . .
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~o~ s tangent to each other at the contact zone between the roller surfaces for all positions of the roller 110 to minimise slippage. Some corrective modification of the curvature 156 may also be necessary to maintain the intersection between the rotational axis of roller 94 and the pitch line at a constant distance from the pivot point of pivot 92 in order to minimise normal spin moment of traction. Such error compensation will result in some variation in the contact zone area between the engaging roller elements to affect the contact pressure for any given contact force exerted by the ten~ion device 152 at the variable leverage aforementioned.
The resultant contact pressure, dependent-on such variables as the contact force, the contact zone area, the roller curvatures and the leverage ratio will vary as a function of the displacement of the roller 110 as depicted by curve 174 in Figure 6. As shown, this resultant pressure curve 174 also has a minimum peak at the neutral position of the ; roller 110.
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carrier 52 associated with the power transmitting gear assembly 40. A sun gear 140 fixed to the input shaft 16 meshes with the planet gear 13~.
The traction roller element 110 which is of substan-tially constant drive diameter is held in frictional drive en~agement with a variable cliameter traction drive element 94 fixed to thP input shaft for rotation therewith about ~he central rotational axis of the transmission. An adju~table tension device 152, such as that disclosed in my prior copending Application aforementioned, bears against the pivotal slide bracket 120 so as to establish the drive engaging pressure between the traction roller elements 110 and 94 at their zone of contact. The zone of co~tact is, of course, shifted by ; rotation of the screw shaft 124 so as to change the transmission - 15 drive ratio and will at the same time change the leverage ratio throuyh which the tension device 152 exerts its force at the zone of contact. Therefore, the contact force will vary for each position of the roller element 110 in accordance with some non-linear function as depicted by curve 168 in Figure 6. The geometry of the arrangement described is such ; that the minimum point 170 on the curve 168 coincides with the neutral condition of the transmission corresponding to a zero drive ratio, the drive ratio being reflected on the ordinate 162. The drive ratio is proportional to the displacement of the roller element 110 as depicted by the ~ 8 _ :, , ' ~ .
7~73(~
straigh~ line curve 158 plotted again~t the roller e1.ement position on the absci3~a 160.
The roller element 110 i~ sh.ifted along shaft 118 between one limit position clS shown in Figure 1 at which the roller elements are of equal diameter as shown by way of example to an opposite limit: po~ition at which the di~neter of roller element 94 is sub~tantially greater than that of roller element 110 in order to vary the dri~e ratio in the drive a~sembly 42 and thereby vary the over-all transmi~ion drive ratio as aforementioned. Ordinarily the roller elements engage each othex along a straight or constant coniaal pitch line corresponding to the pitch angle between the rotational axes of the input shaft 16 and the roller spline ~haft 118.
In order to meet varying torque requirements, the pitch line along which the r~ller elements engage each other iq varied by providing the roller element 94 with a variable pitch curvature 154. The curvature 154 may be de~igned to effect a change in contact pressure as a.function of the transmis~ion drive ratio. A crown curvature 1.56 al~o deviating from the basic pitch angle i~ provided for the roller element 110.
A ~mall amount of pivotal displacement ~f the roller element 110 ~bo~t pivot 92 occur~ during movement of the roller element ~ etween it~ limit position3 for corrective variation in the basi~ pitch ~ngle from-which.the roller curvature~ 154 and 156 ~viate,The curvature~ 154 and 156 are theoretically - g _ . . .
`:` . ' ' ' ~: ' 1 :
~o~ s tangent to each other at the contact zone between the roller surfaces for all positions of the roller 110 to minimise slippage. Some corrective modification of the curvature 156 may also be necessary to maintain the intersection between the rotational axis of roller 94 and the pitch line at a constant distance from the pivot point of pivot 92 in order to minimise normal spin moment of traction. Such error compensation will result in some variation in the contact zone area between the engaging roller elements to affect the contact pressure for any given contact force exerted by the ten~ion device 152 at the variable leverage aforementioned.
The resultant contact pressure, dependent-on such variables as the contact force, the contact zone area, the roller curvatures and the leverage ratio will vary as a function of the displacement of the roller 110 as depicted by curve 174 in Figure 6. As shown, this resultant pressure curve 174 also has a minimum peak at the neutral position of the ; roller 110.
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Claims (6)
1. A change speed transmission, comprising input and output members, a power transmitting year arrangement drivingly interconnecting said input and output members for establishing a relatively high torque power path therebetween, a low torque biasing gear arrangement drivingly connected between the input member and the power transmitting gear arrangement, for establishing a drive ratio between the input and output members, and a variable traction drive driven by the input member for controlling, by means of the torque biasing gear arrangement, said drive ratio, said traction drive including a traction roller rotatable about a fixed axis common to the input and output members.
2. A transmission according to claim 1, wherein said traction drive further includes a driven roller in engagement with said traction roller, and means mounting the driven roller for rotation about a movable axis generally parallel to a basic pitch line along which the rollers engage, and means for displacing the driven roller along said movable axis to vary the drive ratio.
3. A transmission according to claim 2, wherein said rollers have engaging surfaces characterised by curvatures that deviate from the basic pitch line to maintain optimum contact pressure for all positions of the drive roller.
4. A transmission according to claim 2 or 3, wherein said drive ratio is varied as a linear function of the displacement of the driven roller.
5. A transmission according to claim 2 or 3, wherein said traction drive further includes tension control means for exerting a contact force on one of the rollers at a variable leverage ratio.
6. A transmission according to any one of claims 1 to 3, wherein said traction drive includes engaging rollers, means mounting one of the rollers for rotation about a fixed axis, means mounting the other of the rollers about a pivotally displaceable axis, and means for displacing said other of the rollers along said displaceable axis to vary the drive ratio.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/787,372 US4192201A (en) | 1976-08-20 | 1977-04-14 | Traction controlled in-line transmission |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1077305A true CA1077305A (en) | 1980-05-13 |
Family
ID=25141270
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA299,884A Expired CA1077305A (en) | 1977-04-14 | 1978-03-29 | Traction controlled in-line transmission |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS53129766A (en) |
| AU (1) | AU517774B2 (en) |
| CA (1) | CA1077305A (en) |
| DE (1) | DE2815322A1 (en) |
| FR (1) | FR2387387A1 (en) |
| GB (1) | GB1599953A (en) |
| NL (1) | NL7803812A (en) |
| SE (1) | SE7804209L (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ITTO20050778A1 (en) * | 2005-11-02 | 2007-05-03 | Graziano Trasmissioni Spa | VARIABLE REPORT TRANSMISSION CONTINUOUSLY |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB169463A (en) * | 1920-09-24 | 1922-04-20 | Gaston Castel De Courval | Variable-speed and reversing gearing suitable for motor-vehicles |
| US3820416A (en) * | 1973-01-05 | 1974-06-28 | Excelermatic | Variable ratio rotary motion transmitting device |
-
1978
- 1978-02-27 JP JP2197478A patent/JPS53129766A/en active Pending
- 1978-03-29 CA CA299,884A patent/CA1077305A/en not_active Expired
- 1978-03-30 GB GB12566/78A patent/GB1599953A/en not_active Expired
- 1978-04-06 FR FR7810992A patent/FR2387387A1/en not_active Withdrawn
- 1978-04-06 AU AU34840/78A patent/AU517774B2/en not_active Expired
- 1978-04-08 DE DE19782815322 patent/DE2815322A1/en not_active Withdrawn
- 1978-04-11 NL NL7803812A patent/NL7803812A/en not_active Application Discontinuation
- 1978-04-13 SE SE7804209A patent/SE7804209L/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| NL7803812A (en) | 1978-10-17 |
| JPS53129766A (en) | 1978-11-13 |
| AU3484078A (en) | 1979-10-11 |
| FR2387387A1 (en) | 1978-11-10 |
| SE7804209L (en) | 1978-10-15 |
| AU517774B2 (en) | 1981-08-27 |
| DE2815322A1 (en) | 1978-10-19 |
| GB1599953A (en) | 1981-10-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |