CA1154982A - Compound epicyclic cog belt speed reducer - Google Patents
Compound epicyclic cog belt speed reducerInfo
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- CA1154982A CA1154982A CA000350347A CA350347A CA1154982A CA 1154982 A CA1154982 A CA 1154982A CA 000350347 A CA000350347 A CA 000350347A CA 350347 A CA350347 A CA 350347A CA 1154982 A CA1154982 A CA 1154982A
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Abstract
Inventor: Frank L. Stromotich Title: Compound Epicyclic Cog Belt Speed Reducer ABSTRACT
In a speed reducer, a reaction sun is held stationary relative to a frame and an output sun is coaxial with the reaction sun. An idler carrier assembly, rotatable relative to the frame about the common axis of the two suns, carries a planet shaft supporting a reaction planet and an output planet for conjoint rotation and in radial alignment, respectively, with the reaction sun and the output sun. Rotation of the idler carrier assembly effects orbiting of the planet shaft and its planets about the common axis of the suns. Endless loop force-transmitting elements connect corresponding suns and planets. Rotary input power is applied to the planet shaft effecting conjoint rotation of the planets and orbiting of the planets about the suns' axis. The epicyclic motion of the output planet effects rotation of the output sun. In a preferred embodiment, an input shaft carries a separate input sun coaxial with the other suns; the planet shaft supports an input planet in addition to supporting the output and reaction planets; and the input sun and the input planet are connected by an additional endless loop force-transmitting element. The input shaft is driven by a high-speed electric motor at a speed of at least 3,000 rpm and the velocity ratio of the speed reducer is at least 1,000:1.
In a speed reducer, a reaction sun is held stationary relative to a frame and an output sun is coaxial with the reaction sun. An idler carrier assembly, rotatable relative to the frame about the common axis of the two suns, carries a planet shaft supporting a reaction planet and an output planet for conjoint rotation and in radial alignment, respectively, with the reaction sun and the output sun. Rotation of the idler carrier assembly effects orbiting of the planet shaft and its planets about the common axis of the suns. Endless loop force-transmitting elements connect corresponding suns and planets. Rotary input power is applied to the planet shaft effecting conjoint rotation of the planets and orbiting of the planets about the suns' axis. The epicyclic motion of the output planet effects rotation of the output sun. In a preferred embodiment, an input shaft carries a separate input sun coaxial with the other suns; the planet shaft supports an input planet in addition to supporting the output and reaction planets; and the input sun and the input planet are connected by an additional endless loop force-transmitting element. The input shaft is driven by a high-speed electric motor at a speed of at least 3,000 rpm and the velocity ratio of the speed reducer is at least 1,000:1.
Description
3~32 COMPOUND EPICYCLIC COG BELT SPEED REDUCER
The present invention relates to speed reducers and, more specifically, to a compound epicyclic speed reducer having a high velocity ratio, such as at least 1,000:1, and usable for an e~tended period at high input speed for the driving shaft, such as at least 3,000 revolutions per minute.
A speed reducer having a high velocity ratio between the driving and driven components of the reducer is required in applications where it is desired to increase -the output torque o~ the driven comp~nent greatly o~er the input torque of the driving component, or where it is desired to decrease the output speed of the driven component greatly over the input speed of the driving component.
For achieving a high velocity ratio, "ordinary"
gear trains, that is, trains using gears rotatable about axes stationary relative to each other, are undesirable because many sets of gears in series are required to achieve a high ~elocity ratio. While a higher velocity ratio can be achieved with fewer parts by use of worms, worms require precise machining and, in general t have a lower power transmission efficiency than spur gears.
Epicyclic gear trains offer the advantage of requiring fewer sets of gears to achieve a high velocity ratio, resulting in less weight without substantial reduction in power transmission efficiency as compared to ordinary gear trains. However, the gears o epicyclic speed reducers must be precisely machined and precisely positioned. In addition, there is moxe difficulty in ,~
adjusting the velocity ratio from any designed value for an epicyclic speed reducer than ~or an ordinary speed reducer because changing the size of any one gear in an epicyclic speed reducer usually requires repositioning at least some oE the other gears.
Some of the problems with epicyclic speed reducers can be overcome by exotic design. For example, in the device of U.S. patent No. 3,481,222, issued in the name o Baron on February 12, 1969, a "floating"
orbiting planet shaft is provided so -that the planet gears need not be positioned quite so precisely with respect to the sun gears as in an epicyclic speed reducer having a firmly positioned planet shaft.
A problem common to both ordinary and epicyclic speed reducers using meshing gears is that maximum lnput speed is limited. In producing electric motors of a given power rating, for example, the power to cost and power to weight ratios are substantially higher for a high-speed motor, such as a motor having an output speed in the range o~ 3,000 to 20,000 rpm, than Eor a low-speed motor, such as a motor having an output speed in the range of 1,000 to 31 rpm, so that an inexpen sive high velocity ratio speed reducer capable of handling high input speed would be desirable. Conven-tional speed reducers using meshing gears simply cannot be driven above about 3,000 rpm for extended periods because of heat build-up resulting in rapid wear -- at least without the additional expense of high precision machining and/or exotic and expensive gear materials and lubricants or lubrication systems. At high speed, lubricant is flung from the gears by centrifugal force.
Heat build-up and rapid wear at high speed is even more of a problem with worms. A practical upper limit for the input speed of worm gear reducers is about 2,000 rpm.
Lubrication problems also can be overcome somewhat by exotic design. For example, the "~lart reduction pulley", which has a meshing gear epicyclic reducer, uses "splash lubrication" in which lubricant flung from spinning gears contacts the inner periphery of the specially designed reducer housing and splashes back onto the rotating gears. Nevertheless, even the Hart reduction pulley is recommended for use with a motor having an output speed of only 1,750 rpm.
Naturally, total cost is a primary considera-tion in the selection of an electric motor-speed reducer combination producing a desired output speed and torque. In genexal, where low output speed is required, the cost of the speed reducer portion is much greater than the cost of the electric motor portion. Up to now, to achieYe a desired low output speed, the combination of a high-speed motor and a high velocity ratio speed reducer capable of handling high input speed has not been cost effective, because the additional expense of the high input speed, high velocity ratio speed reducer is substantially greater ~ than the cost savings resulting from using a high-; speed motor. Again, it is apparent that an inexpensive high velocity ratio speed reducer capable of handling high input speed is desirable.
For a specific application, ordinary and epicyclic gear trains can be used in combination. For example, the device of Canadian patent No. 824,402, issued in the name of Zucchellini on October 7, 1969, Z
uses an epicyclic reduce~ drivin~ a worm to achieve exact positioning of a slide that can carry machine tools. The devices of Canadian patent No. 922,926, issued in the name of Lemmens on March 20, 1973, and Canadian patent No. 935,668, issued in the name of Roper on October 23, 1973, use variable pitch pulley belt drives connected to the input shaft or the input and output shafts of an epicyclic speed reducer for providing an infinitely variable transmission.
Ordinary and epicyclic gearing also can be connected in series to overcome a disadvantage of either system when used alone. In the Hart reduction pulley, an initial speed reduction is achieved by an open V-belt drive connecting the oùtput pulle~ of a motor and the input pulley of an epicyclic speed reducer. The result is that the total velocity ratio can be altered through a limited range by changing the velocity ratio of the open V-belt drive without changing the velocity ratio of the epicyclic speed reducer.
The Hart reduction pulley Ealls into a further class of speed reducers that includes the devices of Canadian patent No. ~56,655, issued in the name of Helling on May 17, 1949, and the following United States patents:
Morini No. 3,115,794, issued December 31, 1963; and Philpott et al. No. 3,842,685, issued October 22, 1974.
Each of these devices uses some type of endless loop force-transmitting element, such as a belt or a chain, in conjunction with an epicyclic speed reducer. Also, in each of these devices input power is applied directly to the carrier member for the orbiting planet shaft of the epicyclic reducer. An advantage of using endless loop force-transmitting elements that is not recognized in any of these patents is that higher input speed can be accommodated by speed reducers using endless loop force-transmitting elements rather than meshing gears;
and a disadvantage o each of these devices that is not recognized in any of the patents i5 the decreased maximum input speed permitted by driviny a carrier member directly.
The principal object of the present invention is to provide a compact and light speed reducer having a high velocity ratio, such as at least 1,000:1, providing high power transmission e~ficiency, such as about 90 percent, and usable for an extended period at high input speed, such as at least 3,000 rpm.
It also is an object to provide such a speed reducer in a form adaptable to a variety of applications including use in various motor-speed reducer combina-tions, and in reverted or nonreverted, constant velocity ratio or variable velocity ratio, constant output torque or regulated maximum output torque, and instan-taneous or gradual start-up applications.
The foregoing objects can be accomplished by a compound epicyclic speed reducer comprising: a frame; a reaction sun; means for maintaining said reaction sun stationary relative to said frame; an output sun coaxial with said reaction sun, the common axis of said two suns defining a primary axis; at least two planets, one for each o-f said suns, including a reaction planet and an output planet; planet shaft means for carrying said planets for conjoint rotation;
an idler carrier assembly rotatably supporting said planet shaft means spaced from and extending sub-~ t~ 2 stantiall~ parallel to said primary axis, the axis of said planet shaft means supported by sald idler carrier assembly defining a secondary axis; at least two endless loop force-transmitting elements connecting, respectively, said reaction sun and said reaction planet, and said output sun and said ou~put planet;
and rotary input means for driving said planet shaft means and thereby effecting conjoint rotation of said two planets about said secondary axis, rotation of said reaction planet effecting rotation of said idler carrier assembly about sai.d primary axis for orbiting of said planet shaft means and said planets about said primary axis, and rotation of said output planet about said secondary axis in combination with orbiting of said output planet about said primary axis eEfecting rotation of said output sun.
Such objects also can be accomplished by a compound epicyclic speed reducer comprising: a frame;
at least two suns; means mounting said suns on said frame in coaxial relationship, the common axis of said two suns defining a primary axis; means for maintaining one of said suns stationary relative to said frame; at least two planets, one for each of said suns; planet shaft means for carrying said planets for conjoint rotation; an idler carrier assembly rotatably supporting said planet shaft means spaced from and extending sub-stantially parallel to said primary axis, the axis of said planet shaft means supported by said idler carrier assembly d2fining a secondary axis; at least two endless loop force-transmitting elements connecting, respectively, one of said suns and one of said planets, and the other of said suns and the other of said z planets; rotary input means for e:Efecting rotation of said plane~ shaft means and thereby effecting conjoint rotation of said two planets about said secondary axis, rotation of said planets effecting rotation of said idler carrier assembly about said primary axis for orbiting of said planet shaft and said planets about -said primary axis; and a rotary output member rotatably mounted on said frame and driven by rotation of said planets about said secondary axi.s in combination with orbiting of said planets about said primary axis.
Such objects also can be accomplished by rotary drive mechanism comprisiny a high-speed electric motor having a rotary output member rotating a-t a speed of at least 3,000 rpm~ and a compound epicyclic speed reducer having a velocity ratio of at least 1,000:1 and including: an input shaft rotatable about a first axis by rotation of said motor rotary output member; an output shaft coaxial with the input shaft and rotatable relative thereto; three suns, all concentric about said first axis, including a stationary reaction sun, an input sun rotatable with said input shaft and an output sun rotatable with said output shaft; three planets/
including a reaction planet for said reaction sun, an input planet for said input sun and an output planet for said output sun; planet shaft means carrying said three planets for conjoint rotation; an idler carrier member mounting said planet shaft means spaced from and extending substantially parallel to said first axis for orbiting of said planet shaft means about the primary axis; and three endless loop force-transmitting elements for connecting, respectively, said reaction sun and said reaction planet, said input sun and said input planet, and said cutput sun and said output planet.
In drawings which illustra-te embodiments of the invention, Figure 1 is a somewhat diagrammatic end elevation of a compound epic~clic cog belt speed reducer in accordance with t.he present invention, and Figure 2 is a somewhat diagrammatic vertical ~ection taken along line 2--2 of Figure 1, : 10 Figures 3 and 4 are corresponding somewhat diagrammatic fragmentary vertical axial sections of modified forms of speed reducers in accordance with the present invention showing alternative mountings of an electric motor at the input sides of the reducers, Figure 5 is a somewhat diagrammatic fragmen-tary enlarged vertical axial ssction of another embodi-ment of speed reducer in accoxdance with the present invention having a modified planet carrier assembly, Figure 6 is a somewhat diagrammatic vertical axial section of another embodiment of speed reducer in accordance with the present invention having maximum output torque control mechanism, and Figure 7 is a somewhat diagrammatic end elevation of the speed reducer of Figure 6, Figure 8 is a somewhat diagrammatic vertical axial section of another embodiment of speed reducer in accordance with the present invention having a manually-controlled variable diameter reaction sun for changing the velocity ratio of the reducer, and Figure 9 is a somewhat diagrammatic fragmentary section taken along line 9--9 of Figure 8, Figure 10 is a somewhat diagrammatic fragmen-tary vertical axial section o~ another embodiment o~
speed reducer in accordance with the present invention having a power-controlled variable diameter reaction sun;
Figure 11 is a somewhat diagrammatic fragmentary vertical axial section of another embodiment of speed reducer in accordance with the present invention having alternative reaction suns fc~r variable speed control, Figure 12 is a somewhat diagrammatic vertical axial section of another embodiment of speed reducer in accordance with the present invention, illustrating a nonreverted ~orm, Figure 13 is a somewhat diagrammatic vertical axial section of another embodiment of speed reducer in accordance with the present invention, illustrating an "electric wheel" application in which the spee~
reducer is built into the hub of a wheel and an electric ; motor is mounted outside the hub, and Figure 14 is a somewhat diagrammatic vertical axial section of a speed reducer in accordance with the present invention, illustrating a "drum motor"
application in which the speed reducer and an electric motor are mounted inside a drum for rotating the drum.
; The compound epicyclic speed reducer in accordance with the present invention shown in Figures 1 and 2 includes a mounting base 1 supporting a closed, substantially cylindrical housing 2 having opposite end discs 3 and 4 joined by through-bolts 5. The bolts are the reducer.
Input shaft 6 carries an input sun 11 generally at the axial center of the reducer, and output shaft 8 carries an output sun 12 inside the housing adjacent to the output end disc 4. A reaction sun 13 is mounted stationarily in the housing 2 adjacent to the input end disc 3 by screws 14 and has an axial bore 15 throuyh which the input sha~t 6 passes freely. All of the suns are coaxial about the primary axis of the reducer.
Elongated parallel carrier plates 16, spaced apart axially of the reducer, have corresponding central portions located at opposite sides o~ the input sun 11 and project generally diametrally of the reducer to form an idler planet carrier assembly. The central portions of such carrier plates are journaled on input shaft 6 by bearings 17 so as to be ~reel~
rotatable relative to the input shaft. Corresponding swinging ends of the plates are joined by crossbars 18. A spacer tube 19 encircling to the input shaft generally inside the bore 15 through the reaction sun prohibits substantial movement of the idler carrier assembly axially of the input shaft.
A planet shaft 20 is journaled in corresponding end portions of the carrier plates 16 by bearings 21 and is fxeely rotatable relative to the carrier plates.
Such shaft defines an axis -- the secondary axis of the reducer -- parallel to the primary axis and orbital about the primary axis by rotation of the carrier assembly. An input planet 22, an output planet 23 and a reaction planet 24 all are fixed to shaft 20 at axially spaced locations radially aligned, respectively, with input sun 11, output sun 12 and reaction sun 13.
Each planet is connected to its associated sun by an endless loop force--transmitting element 25, 26 or 27.
Preferably, all of the suns and planets are cog wheels or sheaves and all of the endless loop force-transmitting elements are cog belts. Nevertheless, in an application requ.iring high torque ~ransference or in an applicakion where h:igh temperature or stress would shorten the life of cog belts, the planets and suns can be sprockets and the endless loop ~orce-transmitting elements can be chains~
In operation, rotation of input sun 11 by rotation of input shaft 6 necessarily effects rotation of input planet 22 by force transference by the input endless loop Eorce-transmitting element 25. Since all of the pl~nets are :~ixed to planet shaft 20 to rotate conjointly, reaction planet 24 is rotated by rotation of input planet 22 and, consequently, is driven orbitally around the stationary reaction sun 13 ~y force trans~
ference by the reaction endlests loop force-transmitting element 27. Planet shaft 20, the other planets and the idler carrier assembly are swung around the primary axis of the reducer with the reaction planet. Rotation of output planet 23 about the secondary axis and orbiting of such planet about the primary axis effects rotation of output sun 12, and the output shaft 8 carrying such sun, by force transference by the output endless loop force-transmitting element 26, but at a much slower speed than the rotational speed of the input shaft.
The velocity ratio R of the speed reducer, that is, the rotative speed of input shaft 6 relative to the rotative speed of output shaft 8, depends on the relative sizes of the suns and planets and can be determined by the following equation in which it is assumed that all suns and planets are of the same pitch (same number of teeth per unit circumference) and in which "Ni" represents the number of teeth on a sun or planet "i" as designated in the above description:
The present invention relates to speed reducers and, more specifically, to a compound epicyclic speed reducer having a high velocity ratio, such as at least 1,000:1, and usable for an e~tended period at high input speed for the driving shaft, such as at least 3,000 revolutions per minute.
A speed reducer having a high velocity ratio between the driving and driven components of the reducer is required in applications where it is desired to increase -the output torque o~ the driven comp~nent greatly o~er the input torque of the driving component, or where it is desired to decrease the output speed of the driven component greatly over the input speed of the driving component.
For achieving a high velocity ratio, "ordinary"
gear trains, that is, trains using gears rotatable about axes stationary relative to each other, are undesirable because many sets of gears in series are required to achieve a high ~elocity ratio. While a higher velocity ratio can be achieved with fewer parts by use of worms, worms require precise machining and, in general t have a lower power transmission efficiency than spur gears.
Epicyclic gear trains offer the advantage of requiring fewer sets of gears to achieve a high velocity ratio, resulting in less weight without substantial reduction in power transmission efficiency as compared to ordinary gear trains. However, the gears o epicyclic speed reducers must be precisely machined and precisely positioned. In addition, there is moxe difficulty in ,~
adjusting the velocity ratio from any designed value for an epicyclic speed reducer than ~or an ordinary speed reducer because changing the size of any one gear in an epicyclic speed reducer usually requires repositioning at least some oE the other gears.
Some of the problems with epicyclic speed reducers can be overcome by exotic design. For example, in the device of U.S. patent No. 3,481,222, issued in the name o Baron on February 12, 1969, a "floating"
orbiting planet shaft is provided so -that the planet gears need not be positioned quite so precisely with respect to the sun gears as in an epicyclic speed reducer having a firmly positioned planet shaft.
A problem common to both ordinary and epicyclic speed reducers using meshing gears is that maximum lnput speed is limited. In producing electric motors of a given power rating, for example, the power to cost and power to weight ratios are substantially higher for a high-speed motor, such as a motor having an output speed in the range o~ 3,000 to 20,000 rpm, than Eor a low-speed motor, such as a motor having an output speed in the range of 1,000 to 31 rpm, so that an inexpen sive high velocity ratio speed reducer capable of handling high input speed would be desirable. Conven-tional speed reducers using meshing gears simply cannot be driven above about 3,000 rpm for extended periods because of heat build-up resulting in rapid wear -- at least without the additional expense of high precision machining and/or exotic and expensive gear materials and lubricants or lubrication systems. At high speed, lubricant is flung from the gears by centrifugal force.
Heat build-up and rapid wear at high speed is even more of a problem with worms. A practical upper limit for the input speed of worm gear reducers is about 2,000 rpm.
Lubrication problems also can be overcome somewhat by exotic design. For example, the "~lart reduction pulley", which has a meshing gear epicyclic reducer, uses "splash lubrication" in which lubricant flung from spinning gears contacts the inner periphery of the specially designed reducer housing and splashes back onto the rotating gears. Nevertheless, even the Hart reduction pulley is recommended for use with a motor having an output speed of only 1,750 rpm.
Naturally, total cost is a primary considera-tion in the selection of an electric motor-speed reducer combination producing a desired output speed and torque. In genexal, where low output speed is required, the cost of the speed reducer portion is much greater than the cost of the electric motor portion. Up to now, to achieYe a desired low output speed, the combination of a high-speed motor and a high velocity ratio speed reducer capable of handling high input speed has not been cost effective, because the additional expense of the high input speed, high velocity ratio speed reducer is substantially greater ~ than the cost savings resulting from using a high-; speed motor. Again, it is apparent that an inexpensive high velocity ratio speed reducer capable of handling high input speed is desirable.
For a specific application, ordinary and epicyclic gear trains can be used in combination. For example, the device of Canadian patent No. 824,402, issued in the name of Zucchellini on October 7, 1969, Z
uses an epicyclic reduce~ drivin~ a worm to achieve exact positioning of a slide that can carry machine tools. The devices of Canadian patent No. 922,926, issued in the name of Lemmens on March 20, 1973, and Canadian patent No. 935,668, issued in the name of Roper on October 23, 1973, use variable pitch pulley belt drives connected to the input shaft or the input and output shafts of an epicyclic speed reducer for providing an infinitely variable transmission.
Ordinary and epicyclic gearing also can be connected in series to overcome a disadvantage of either system when used alone. In the Hart reduction pulley, an initial speed reduction is achieved by an open V-belt drive connecting the oùtput pulle~ of a motor and the input pulley of an epicyclic speed reducer. The result is that the total velocity ratio can be altered through a limited range by changing the velocity ratio of the open V-belt drive without changing the velocity ratio of the epicyclic speed reducer.
The Hart reduction pulley Ealls into a further class of speed reducers that includes the devices of Canadian patent No. ~56,655, issued in the name of Helling on May 17, 1949, and the following United States patents:
Morini No. 3,115,794, issued December 31, 1963; and Philpott et al. No. 3,842,685, issued October 22, 1974.
Each of these devices uses some type of endless loop force-transmitting element, such as a belt or a chain, in conjunction with an epicyclic speed reducer. Also, in each of these devices input power is applied directly to the carrier member for the orbiting planet shaft of the epicyclic reducer. An advantage of using endless loop force-transmitting elements that is not recognized in any of these patents is that higher input speed can be accommodated by speed reducers using endless loop force-transmitting elements rather than meshing gears;
and a disadvantage o each of these devices that is not recognized in any of the patents i5 the decreased maximum input speed permitted by driviny a carrier member directly.
The principal object of the present invention is to provide a compact and light speed reducer having a high velocity ratio, such as at least 1,000:1, providing high power transmission e~ficiency, such as about 90 percent, and usable for an extended period at high input speed, such as at least 3,000 rpm.
It also is an object to provide such a speed reducer in a form adaptable to a variety of applications including use in various motor-speed reducer combina-tions, and in reverted or nonreverted, constant velocity ratio or variable velocity ratio, constant output torque or regulated maximum output torque, and instan-taneous or gradual start-up applications.
The foregoing objects can be accomplished by a compound epicyclic speed reducer comprising: a frame; a reaction sun; means for maintaining said reaction sun stationary relative to said frame; an output sun coaxial with said reaction sun, the common axis of said two suns defining a primary axis; at least two planets, one for each o-f said suns, including a reaction planet and an output planet; planet shaft means for carrying said planets for conjoint rotation;
an idler carrier assembly rotatably supporting said planet shaft means spaced from and extending sub-~ t~ 2 stantiall~ parallel to said primary axis, the axis of said planet shaft means supported by sald idler carrier assembly defining a secondary axis; at least two endless loop force-transmitting elements connecting, respectively, said reaction sun and said reaction planet, and said output sun and said ou~put planet;
and rotary input means for driving said planet shaft means and thereby effecting conjoint rotation of said two planets about said secondary axis, rotation of said reaction planet effecting rotation of said idler carrier assembly about sai.d primary axis for orbiting of said planet shaft means and said planets about said primary axis, and rotation of said output planet about said secondary axis in combination with orbiting of said output planet about said primary axis eEfecting rotation of said output sun.
Such objects also can be accomplished by a compound epicyclic speed reducer comprising: a frame;
at least two suns; means mounting said suns on said frame in coaxial relationship, the common axis of said two suns defining a primary axis; means for maintaining one of said suns stationary relative to said frame; at least two planets, one for each of said suns; planet shaft means for carrying said planets for conjoint rotation; an idler carrier assembly rotatably supporting said planet shaft means spaced from and extending sub-stantially parallel to said primary axis, the axis of said planet shaft means supported by said idler carrier assembly d2fining a secondary axis; at least two endless loop force-transmitting elements connecting, respectively, one of said suns and one of said planets, and the other of said suns and the other of said z planets; rotary input means for e:Efecting rotation of said plane~ shaft means and thereby effecting conjoint rotation of said two planets about said secondary axis, rotation of said planets effecting rotation of said idler carrier assembly about said primary axis for orbiting of said planet shaft and said planets about -said primary axis; and a rotary output member rotatably mounted on said frame and driven by rotation of said planets about said secondary axi.s in combination with orbiting of said planets about said primary axis.
Such objects also can be accomplished by rotary drive mechanism comprisiny a high-speed electric motor having a rotary output member rotating a-t a speed of at least 3,000 rpm~ and a compound epicyclic speed reducer having a velocity ratio of at least 1,000:1 and including: an input shaft rotatable about a first axis by rotation of said motor rotary output member; an output shaft coaxial with the input shaft and rotatable relative thereto; three suns, all concentric about said first axis, including a stationary reaction sun, an input sun rotatable with said input shaft and an output sun rotatable with said output shaft; three planets/
including a reaction planet for said reaction sun, an input planet for said input sun and an output planet for said output sun; planet shaft means carrying said three planets for conjoint rotation; an idler carrier member mounting said planet shaft means spaced from and extending substantially parallel to said first axis for orbiting of said planet shaft means about the primary axis; and three endless loop force-transmitting elements for connecting, respectively, said reaction sun and said reaction planet, said input sun and said input planet, and said cutput sun and said output planet.
In drawings which illustra-te embodiments of the invention, Figure 1 is a somewhat diagrammatic end elevation of a compound epic~clic cog belt speed reducer in accordance with t.he present invention, and Figure 2 is a somewhat diagrammatic vertical ~ection taken along line 2--2 of Figure 1, : 10 Figures 3 and 4 are corresponding somewhat diagrammatic fragmentary vertical axial sections of modified forms of speed reducers in accordance with the present invention showing alternative mountings of an electric motor at the input sides of the reducers, Figure 5 is a somewhat diagrammatic fragmen-tary enlarged vertical axial ssction of another embodi-ment of speed reducer in accoxdance with the present invention having a modified planet carrier assembly, Figure 6 is a somewhat diagrammatic vertical axial section of another embodiment of speed reducer in accordance with the present invention having maximum output torque control mechanism, and Figure 7 is a somewhat diagrammatic end elevation of the speed reducer of Figure 6, Figure 8 is a somewhat diagrammatic vertical axial section of another embodiment of speed reducer in accordance with the present invention having a manually-controlled variable diameter reaction sun for changing the velocity ratio of the reducer, and Figure 9 is a somewhat diagrammatic fragmentary section taken along line 9--9 of Figure 8, Figure 10 is a somewhat diagrammatic fragmen-tary vertical axial section o~ another embodiment o~
speed reducer in accordance with the present invention having a power-controlled variable diameter reaction sun;
Figure 11 is a somewhat diagrammatic fragmentary vertical axial section of another embodiment of speed reducer in accordance with the present invention having alternative reaction suns fc~r variable speed control, Figure 12 is a somewhat diagrammatic vertical axial section of another embodiment of speed reducer in accordance with the present invention, illustrating a nonreverted ~orm, Figure 13 is a somewhat diagrammatic vertical axial section of another embodiment of speed reducer in accordance with the present invention, illustrating an "electric wheel" application in which the spee~
reducer is built into the hub of a wheel and an electric ; motor is mounted outside the hub, and Figure 14 is a somewhat diagrammatic vertical axial section of a speed reducer in accordance with the present invention, illustrating a "drum motor"
application in which the speed reducer and an electric motor are mounted inside a drum for rotating the drum.
; The compound epicyclic speed reducer in accordance with the present invention shown in Figures 1 and 2 includes a mounting base 1 supporting a closed, substantially cylindrical housing 2 having opposite end discs 3 and 4 joined by through-bolts 5. The bolts are the reducer.
Input shaft 6 carries an input sun 11 generally at the axial center of the reducer, and output shaft 8 carries an output sun 12 inside the housing adjacent to the output end disc 4. A reaction sun 13 is mounted stationarily in the housing 2 adjacent to the input end disc 3 by screws 14 and has an axial bore 15 throuyh which the input sha~t 6 passes freely. All of the suns are coaxial about the primary axis of the reducer.
Elongated parallel carrier plates 16, spaced apart axially of the reducer, have corresponding central portions located at opposite sides o~ the input sun 11 and project generally diametrally of the reducer to form an idler planet carrier assembly. The central portions of such carrier plates are journaled on input shaft 6 by bearings 17 so as to be ~reel~
rotatable relative to the input shaft. Corresponding swinging ends of the plates are joined by crossbars 18. A spacer tube 19 encircling to the input shaft generally inside the bore 15 through the reaction sun prohibits substantial movement of the idler carrier assembly axially of the input shaft.
A planet shaft 20 is journaled in corresponding end portions of the carrier plates 16 by bearings 21 and is fxeely rotatable relative to the carrier plates.
Such shaft defines an axis -- the secondary axis of the reducer -- parallel to the primary axis and orbital about the primary axis by rotation of the carrier assembly. An input planet 22, an output planet 23 and a reaction planet 24 all are fixed to shaft 20 at axially spaced locations radially aligned, respectively, with input sun 11, output sun 12 and reaction sun 13.
Each planet is connected to its associated sun by an endless loop force--transmitting element 25, 26 or 27.
Preferably, all of the suns and planets are cog wheels or sheaves and all of the endless loop force-transmitting elements are cog belts. Nevertheless, in an application requ.iring high torque ~ransference or in an applicakion where h:igh temperature or stress would shorten the life of cog belts, the planets and suns can be sprockets and the endless loop ~orce-transmitting elements can be chains~
In operation, rotation of input sun 11 by rotation of input shaft 6 necessarily effects rotation of input planet 22 by force transference by the input endless loop Eorce-transmitting element 25. Since all of the pl~nets are :~ixed to planet shaft 20 to rotate conjointly, reaction planet 24 is rotated by rotation of input planet 22 and, consequently, is driven orbitally around the stationary reaction sun 13 ~y force trans~
ference by the reaction endlests loop force-transmitting element 27. Planet shaft 20, the other planets and the idler carrier assembly are swung around the primary axis of the reducer with the reaction planet. Rotation of output planet 23 about the secondary axis and orbiting of such planet about the primary axis effects rotation of output sun 12, and the output shaft 8 carrying such sun, by force transference by the output endless loop force-transmitting element 26, but at a much slower speed than the rotational speed of the input shaft.
The velocity ratio R of the speed reducer, that is, the rotative speed of input shaft 6 relative to the rotative speed of output shaft 8, depends on the relative sizes of the suns and planets and can be determined by the following equation in which it is assumed that all suns and planets are of the same pitch (same number of teeth per unit circumference) and in which "Ni" represents the number of teeth on a sun or planet "i" as designated in the above description:
2~ 12 For illustration, input sun 11, output planet 23 and reaction planet 24 all can have the same number of teeth "x", the relative numbers of teeth o~ the input sun 11 and the input planet 22 can be about 1:2, or x:2x, and the relative numbers of teeth of the input planet 22 and the reaction sun 13 can be about 1:2, or 2x:4x, as shown in the drawings, in which case the velocity ratio equation can be reduced to the following:
17 (2x)(4x) R = 1 (x)(x) _ - l3 (x)(N12) 12 22 In this instance the velocity ratio R is totally dependent on the relative sizes of the output sun 12 and the reaction sun 13. If such suns are the same size, the velocity ratio is infinite, that is, the output shaft ~ will not rotate regardless of whether or not the input shaft is rotated; if the output sun is larger than *he reaction sun, the velocity ratio i5 negative, that is, the output shaft will rotate in the opposite sense from the sense of rotation of the input shaft; and if the output sun is smaller than the reaction sun, the velocity ratio is positive, that is, the output shaft will rotate in the same sense as the sense of rotation of the input shaft.
rro obtain a high ~elocity ratio, either positive or negative, the outpu-t sun should be only slightly larger or smaller than the reaction sun.
Where cog wheels are used, the output sun can ha~e only one more or one less tooth than the reaction sun.
For example, in a represenative installation the output sun can be a cog wheel having 150 teeth and the reaction sun can be a cog wheel having 151 teeth, in which case the velocity xatio is about 1,050:1.
The velocity ratio can be changed substantially by changing the size of one or more of the suns or planets slightly, particularly the output sun or the reaction sun. For example, adding one tGoth to the reaction sun, so that the reaction sun has 152 teeth, cogs, without changing the size of the output sun, so that the output sun still has 150 teeth, results in a velocity ratio of about 525:1, that is, a 50 percent reduction in the velocity ratio. Such a slight change can be accomplished easily without altering the ~rame size or design by substituting one cog wheel for another. In contrast, in known systems using rneshing sun and planet gears, the velocity ratio cannot be changed wi.thout providing cne or more new or additional sets of precisely machined gears, which often necessitates a change i.n ~rame size or design.
The most important advantage o~ a speed : reducer in accordance with the present invention is that such reducer can handle ~ery high input speed for an extended period. Sets of wheels or sprockets connected by endless loop force-transmitting elements can be dri.ven àt a much higher speed than meshing gears of the same size, primarily because by use of flexible endless loop force-transmitting elements transmitted force is spread throu~h several wheel or sprocket teeth, rather than being concentrated on one or two gear teeth as in meshing gears. In addition, spreading transmit-ted force through several teeth allows use of li~hter wheel ox spxocket materials having less strength than would be required for meshing gears transferring the same force.
To accomn~odate the fastest input speed possi~le, the input sun always should be effectively smaller than, or at least no larger than, the input planet so that the planet shaft rotates at a slower speed relative to the carrier assembly than the input shaft. Preferably the input planet is two to ten times larger than the input sun. In the embodiment of the invention shown in Figures 1 and 2, the reduction ratio Rp from the input shaft 6 to the planet shaft 20, that is, the rotative speed of the input shaft relative to the rotative speed of the planet shaft, can be determined b~ the following equati~n:
~12 4N.
Rp = N~
1 ~ N
and, as in the previous illustration, if input sun 11, output planet 23 and re~ction planet 24 have "x"
teeth, input planet 22 has 2x teeth, and reaction sun 13 has 4x teeth, the equation can be reduced as follows:
Rp = ~ = 7 = 2.33:1.
Accordin~ly, the planet shaft would rotate at somewhat less than one-half the spee~ of rotation of the input shaft and in the same sense as the input shaft.
Similarly, it is preEerred that the reaction planet be substantially smaller than the reaction sun, such as no greater than one-half the size of khe reaction sun, so that the idler carrier assembly rotates e~en slowerO The reduction ratio Rc from the input sha~t to the carriex assembly, that is, the rotative speed o~ the input shaft ralati~e to the rotative speed of the carrier assembly, can be determined by the ollowing equation:
R = 1 - --16 which, assuming the same relative sizes o~ the suns and planets as before, reduces to R - - 7:1 Accordingly, the carrier assembly would rotate at one-seventh the speed of xotation of the i.nput shaft, one-third the speed of the speed of rotation of the planet shaft, and in the opposite sense from the sense of rotation of the input shaft and planet shaft.
Using small planets also reduces the inertia of the carrier assembly so that less power is required to start the carrier assembly rotating.
In prior art devices in which a planet carrier assembly is ~otated directly and, in affect, serves as the input component of the reducer, maximum input speed is limited because the planets and planet shaft carried by the carrier assembly rotate faster than, or at about the same speed as, the carrier 9~
assembly. Accordingly, in such prior art devices it is the maximum speed o~ rotation of the planet shaft or carrier member that determines the m~imum input speed, whereas in the present invention ma~imum input speed is limited only by the maximum permissible speed of rotation of the input shaft. Considering that in the present invention the input shaft rotates several times faster than the plane-t shaft, it will be recognized that the speed reducer of the present invention can handle an input speed several times faster, such as 10,000 rpm or even faster, than prior epicyclic speed reducers having carrier members driven directly.
Specialized applications of the speed reducer of the present invention are shown in Figures 3 through 14. As shown in Figure 3, the housing input end disc
17 (2x)(4x) R = 1 (x)(x) _ - l3 (x)(N12) 12 22 In this instance the velocity ratio R is totally dependent on the relative sizes of the output sun 12 and the reaction sun 13. If such suns are the same size, the velocity ratio is infinite, that is, the output shaft ~ will not rotate regardless of whether or not the input shaft is rotated; if the output sun is larger than *he reaction sun, the velocity ratio i5 negative, that is, the output shaft will rotate in the opposite sense from the sense of rotation of the input shaft; and if the output sun is smaller than the reaction sun, the velocity ratio is positive, that is, the output shaft will rotate in the same sense as the sense of rotation of the input shaft.
rro obtain a high ~elocity ratio, either positive or negative, the outpu-t sun should be only slightly larger or smaller than the reaction sun.
Where cog wheels are used, the output sun can ha~e only one more or one less tooth than the reaction sun.
For example, in a represenative installation the output sun can be a cog wheel having 150 teeth and the reaction sun can be a cog wheel having 151 teeth, in which case the velocity xatio is about 1,050:1.
The velocity ratio can be changed substantially by changing the size of one or more of the suns or planets slightly, particularly the output sun or the reaction sun. For example, adding one tGoth to the reaction sun, so that the reaction sun has 152 teeth, cogs, without changing the size of the output sun, so that the output sun still has 150 teeth, results in a velocity ratio of about 525:1, that is, a 50 percent reduction in the velocity ratio. Such a slight change can be accomplished easily without altering the ~rame size or design by substituting one cog wheel for another. In contrast, in known systems using rneshing sun and planet gears, the velocity ratio cannot be changed wi.thout providing cne or more new or additional sets of precisely machined gears, which often necessitates a change i.n ~rame size or design.
The most important advantage o~ a speed : reducer in accordance with the present invention is that such reducer can handle ~ery high input speed for an extended period. Sets of wheels or sprockets connected by endless loop force-transmitting elements can be dri.ven àt a much higher speed than meshing gears of the same size, primarily because by use of flexible endless loop force-transmitting elements transmitted force is spread throu~h several wheel or sprocket teeth, rather than being concentrated on one or two gear teeth as in meshing gears. In addition, spreading transmit-ted force through several teeth allows use of li~hter wheel ox spxocket materials having less strength than would be required for meshing gears transferring the same force.
To accomn~odate the fastest input speed possi~le, the input sun always should be effectively smaller than, or at least no larger than, the input planet so that the planet shaft rotates at a slower speed relative to the carrier assembly than the input shaft. Preferably the input planet is two to ten times larger than the input sun. In the embodiment of the invention shown in Figures 1 and 2, the reduction ratio Rp from the input shaft 6 to the planet shaft 20, that is, the rotative speed of the input shaft relative to the rotative speed of the planet shaft, can be determined b~ the following equati~n:
~12 4N.
Rp = N~
1 ~ N
and, as in the previous illustration, if input sun 11, output planet 23 and re~ction planet 24 have "x"
teeth, input planet 22 has 2x teeth, and reaction sun 13 has 4x teeth, the equation can be reduced as follows:
Rp = ~ = 7 = 2.33:1.
Accordin~ly, the planet shaft would rotate at somewhat less than one-half the spee~ of rotation of the input shaft and in the same sense as the input shaft.
Similarly, it is preEerred that the reaction planet be substantially smaller than the reaction sun, such as no greater than one-half the size of khe reaction sun, so that the idler carrier assembly rotates e~en slowerO The reduction ratio Rc from the input sha~t to the carriex assembly, that is, the rotative speed o~ the input shaft ralati~e to the rotative speed of the carrier assembly, can be determined by the ollowing equation:
R = 1 - --16 which, assuming the same relative sizes o~ the suns and planets as before, reduces to R - - 7:1 Accordingly, the carrier assembly would rotate at one-seventh the speed of xotation of the i.nput shaft, one-third the speed of the speed of rotation of the planet shaft, and in the opposite sense from the sense of rotation of the input shaft and planet shaft.
Using small planets also reduces the inertia of the carrier assembly so that less power is required to start the carrier assembly rotating.
In prior art devices in which a planet carrier assembly is ~otated directly and, in affect, serves as the input component of the reducer, maximum input speed is limited because the planets and planet shaft carried by the carrier assembly rotate faster than, or at about the same speed as, the carrier 9~
assembly. Accordingly, in such prior art devices it is the maximum speed o~ rotation of the planet shaft or carrier member that determines the m~imum input speed, whereas in the present invention ma~imum input speed is limited only by the maximum permissible speed of rotation of the input shaft. Considering that in the present invention the input shaft rotates several times faster than the plane-t shaft, it will be recognized that the speed reducer of the present invention can handle an input speed several times faster, such as 10,000 rpm or even faster, than prior epicyclic speed reducers having carrier members driven directly.
Specialized applications of the speed reducer of the present invention are shown in Figures 3 through 14. As shown in Figure 3, the housing input end disc
3 can have an outward projecting mounting flange 28 on which the base 29 of a standard ~rame motor 30 can be stationarily mounted with the motor output shaft 31 in registration with the speed reducer input sha~t 6.
Such two shafts can be directly connected by a coupling 32.
Alternatively r as shown in Figure 4, the housing input end disc 3 can have outward projecting mounting brackets 33 spaced on opposite sides o~ the input shaf-t 6 such that a flange frame motor 34 can be stationarily mounted on such brackets with its output shaft 35 in registration with the speed reducer input shaft 6 and connected to such input shaft by a coupling 36.
For very high speed or high torque applications, it is preferred that the carrier assembly be balanced, that is, have its center of gravity on the primary axis. In the duplex carrier assembly shown in Fiyure 5, two sets of planets are carried, respectively, by two separate planet sha~ts 20 journaled in opposite end portions o~ the carrier plates 16 by bearings 17.
Each set o planets includes an input planet 22, an output planet 23 and a reaction planet 24, each o the same size as the corresponding planet of the other set. The input shaft 6 carries two identical input suns ll side-by-side between the carrier plates. ~ach input sun is radially aligned with one o the input planets and is connected thereto by an endless loop force-transmitting element 25. A single endless loop force-transmitting element 27 operahly connects the two reaction planets 24 and the reaction sun 13.
Similarly, a single endless loop force-transmitting element would connect the two output planets 23 and the output sun (not shown). In other respects, the embodiment of the present invention shown in Figure 5 is identical to the embodiment shown in Figures 1 and 2. While two sets o~ planets are shown in Figure 5, three or more sets could be provided, preferably spaced uniformly circumferentially around the primar~
axis of the reducer.
The embodiment o the present invention shown in Figures 6 and 7 al~o uses a substantially cylindrical housing 2 h~ving opposite input and output end discs 3 and 4, respectively. Rather than being ; fixed to the input end disc, the reaction sun 13 is fixed on a sleeve 37 journaled in a bearing 38 carried in an aperture through the center of the input end disc. A brake disc 39 also is ~ixed to the sleeve, but outside of the housing, and a clamping brake mechanism 40 is provided to clamp or release the brake disc, thereby resistin~ rotation of the reaction sun or permitting it to rotate Ereely.
The input sha~t 6 of such reducer extends through the bore of sleeve 37 and, as in the previous embodiments, has its inner end portion received in a bearing lO carried in a blind axial bore in the inner end of vutput shaft 8 extending through the housing output end disc 4. The input sun 11 carried by the input shaft is connected to the input planet 22 carried by the planet shaft 20 b~ an endless loop force-transmitting element 25. Such planet shaft is supported for orbiting about the primary axis of the reducer by an idler carrier disc 41 journaled on sleeve 37 by a bearing 42 and freely rotatable relative to such sleeve. A suitable fastener, such as a nut, at the inner end portion o~ slee~e 37 prevents sliding of the carrier disc axially of such sleeve. The output planet 23 and the reaction planet 24 are carried at the opposite end portions of the planet shaft 2~ in radial alignment with their corresponding output and reaction suns 12 and 13, respectively, and are connected to such suns by endless loop force-transmitting elements 26 and 27, respectively.
A further modi~ication of the embodiment shown in ~igures 6 ancl 7 is the provision of a clamping brake mechanism 43 for the idler carrier disc 41.
Such brake is carried at the inner periphery of housing 2 and is actuatable to securely clamp the carrier disc, and thereby pre~ent its rotation, and is releasable for allowing free rotation of the caxrier disc.
1~
In use, with brake 40 ac-tuated for preventing rotation of the brake disc 39 and the reaction sun 13, and with brake 43 released ~or permitting free rotation of the carrier disc, the embodiment o~ Figure 7 operates the same as the embodiment of Figures l and ~. ~owever, the speed reducer o~ Figure 6 can be converted from epicyclic to ordinary operation by simultaneously releasing brake 40 for permitting free rotation of the reaction sun and applying brake 43 for preventing rotation of the carrier disc. In this instance, the primary and secondary axes o~ the reducer remain stationary relative to each other and the reducer acts as a two-stage ordinary speed reducer. The velocity ratio is the product of the ratios of the input and output sets, that is, the product of N22/Nll and Nl2/N23. Thls product will be several times less than the velocity ratio in epicyclic operation.
Brake 40 and brake disc 39 also can be used in cooperation to determine the maximum output torque transferable by output shaft ~. With brake 43 released, the frictional resistance applied by brake 40 to the brake disc can be selected at any desired ~alue so that the reaction sun will slip if the applied torque exceeds a predetermined value. This would be beneficial, for example, if the load driven by the output shaft becomes jammed, preventin~ rotation of the output shaft, whereupon the brake disc would slip in its brake and permit rotation of the reaction sun before the reducer or the motor drivin~ the input shaft is damaged.
Brake 40 and brake disc 39 also can be used in cooperation for ~radual, as opposed to instantaneous, "3~
start-up. As discussed above, the present in~ention permits us~ of light, inexpensive high-speed electric motors for driving input shaft 6. It can take such a motor a substantial period to reach its designed operating speed, and if a substantial load is applied immediately, the motor coulcl stall before the operatiny speed is reached. With bra~e 43 released ~or allowing free rotation of the carrier disc 41 and with brake 40 released enabling free rotation of brake disc 39 and reaction sun 24, e~en if a substantial load is applied to the output shaft, very little torque need be applied to the input sha~t to start the carrier member revolving because the reaction sun is free to rota-te. As the motor reaches its designed output speed, brake 40 can be applied gradually, whereupon the output shaft begins to turn, until finally the brake is fully applied resulting in the reaction sun heing held stationary relative to the housing and the output shaft being rotated at maximum speed in epicyclic operation.
The embodiment of the present invention shown in Figures 8 and 9 is ~ery similar to the embodi-ment shown in Figures 6 and 7, the major differences being that the reaction sun 13 in Figures 8 and 9 is fixed to the housing input end disc 3 and is of variable effecti~e circumferential extent for changing the velocity ratio of the reducer. ~s best seen in Figure 9, the reaction sun 13 includes a central core portion 45 surrounded by a somewhat resilient annular outer strip 46. The adjacent ends of the annular strip do not abut, but rather define a narrow ~ap 47 at the top of the reaction sun. ~uch ends are movable toward and away from each other for reducing or increasiny the effective circumferential extent of the reaction sun by manually turning a worm 48 meshing with a worm gear 49 formed integral with a sleeve nut 50. The sleeve nut, serving as a turnbuckle, receives oppositely threaded screws 51 projecting from plates 52 rigidly attached to the innex peripheries of the opposite end portions of the annular strip 46.
Rotation of worm gear ~9 in one direction will reduce the effective size of the reaction sun while rotation of the worm gear in the opposite direction will increase the effective size of the sun. As previously discussed, even a slight change in the effective size of the reaction sun effects a substan-tially change in the velocity ratio of the reducer.
As shown in Figure 9, an idler pulley 53 can be provided to tension the reaction endless loop force-transmitting element 27 despite changes in the effective size of the reaction sun.
As shown in Figure 10, the modifications of Figures 6 and 7 and Figures 8 and 9 can be combined.
The embodiment of Figure 10, like the embodiment of Figures 6 and 7, has a brake disc 39 and reaction sun 13 both fixed to a sleeve 37 rotatably mounted in the housing input end disc 3. The construction of the reaction sun of the embodiment of Figure 10 is substan-tially identical to the construction of the reaction sun in Figures 8 and 9, with the exception that an electric motor 54 is provided for turning worm 48 to adjust the effective circumferential extent of the reaction sun. Power to the electric motor 5~ is supplied through slip rings 55. Accordingly, the velocity ra~io of the spee~ reducer can be adjusted from a remote location for speed control of the output shaft.
The embodiment o~ the present invention shown in Figure 11 has two reaction suns 13' and 13l' in side-by-side arrangement, each ha~ing its own associated brake disc 39' or 39". The diameters of the two reaction suns are slightly different. The reaction sun 13' adjacent to the housing input end disc 3 is fixed to a sleeve 56 carrying the clutch disc 3~' and extending through the central aperture in such end disc. The other ~eaction sun 13" is fixed to a sleeve 58 extending through the bore of sleeve 56 and carrying the other brake disc 39". Both sleeves are freely rotatable relative to each other and relati~e to the housing input end disc.
The planet shaft 2~ carried by the idler carrier assembly (not shown) has two reaction planets 24' and 24" connected to their corresponding reaction suns by endless loop f~rce-transmitting elements 27' and 271lo Separate brakes (not shown) are provided for the two brake discs. In all other respects, the embodiment of Figure 11 is identical to the embodiment of Figures 6 and 7.
In operation, one or the other of the brake discs is fixed by actuation o~ its associated brake for maintaining the corresponding reaction sun stationary while the other brake disc and reaction sun are free to rotate. Accordingly, either of two velocity ratios can be selected depending on which brake disc and reaction sun are maintained stationary.
~l~L5~Z
Figure 12 illustrates a "nonre~erte~" embodi-ment of the present invention, that is, an embodiment in which the input and output members are not coaxial, using a substantially cylindrical housing 2 having opposite end discs 59 and 60. An output sleeve 8' is journaled in bearings 9' carried in an aperture throuyh the center oF end disc 60 and is freely rotatable relative to such end disc. Inside the housing, an output sun 12 is f.ixed to the output sleeve and a reaction sun 13 having a large central bore 15 recei~ing the sleeve is ~ixed to the housing end disc 60. The suns are coaxial about the axis of the output sleeve --the primary axis of the reducer. An idler carrier disc 41 is rotatably mounted on the inner end portion of the output sleeve by a bearing 42. Sliding of the carrier disc axially of the output sleeve is prevented by a fastener such as a nut 61.
A light, high-speed electric motor 62 is mounted at the outer margin of the idler carrier disc with its output shaft projecting parallel to but spaced ~rom the axis o~ output sleeve 8'. The motor shaft serves as the planet shaft 20' for the output planet 23 and the reaction planet 24 aligned, respect-ively, with output sun 12 and reaction sun 13. Such planets are fixed to the output shaft for conjoint rotation and are connected to their respective suns by endless loop force-transmitting elements 26 and 27.
Power to the electric mo~or is supplied through slip rings 55 mounted on a stationary sleeve 63 projec-ting inward from housing end disc 59 and coaxial with the output sleeve 8'. The speed reducer of Figure 12 can be conveniently mounted with a separate shaft 64 ex-tendin~ through the bores of sleeves 8' and 63, which shaft can be stationary or movable without interferring wi-th operation o~ the reducer. ~lterna-tively, output sleeve 8' can have internal threads complemental to external threads of shaft 64, and sha~t 64 can be nonrotatable, such that rotation of the output sleeve moves shaft 64 axially through the reducer.
In operation, rotation of reaction planet 2 by rotation of the motor output shaft 20' effects rotation of the entire carrier assembly, including the motor, about the stationary reaction sun 13. Rotation of output planet 23 about the axis of the motor output shaft and orbitin~ of such planet about the primary axis of the reducer effects rotation of output sun 12 and output shaft 8' carr~ing such sun. The velocity ratio R of the speed reducer, that is, the rotative speed of the motor output shaft acting as the planet sha~t 20' as compared to the rotative speed of output shaft 8' can be shown to be represented by the following equation:
R 1 Nl3N23 If the t~o planets are the same size, each havin~ "x"
teeth, and the relative numbexs o~ teeth of the reaction planet 24 and the reaction sun 13 is 1:8, or lx:8x, the velocity ratio equation can be reduced to the following:
1 ~ x .~ 7 R ~ - N 3x = N~3 xN12 12 This equation is the same a~; the reduced equation for the embodiment of Figures 1 and 2. Accordin~lY, if the output sun is a co~ wheel having 150 teeth and the reaction sun is a cog wheel having 151 teeth, the velocity ratio is 1,050:1.
Figure 13 illustrates an "electric wheel"
application using an electric motor and a speed reducer in accordance with the present invention for drivin~ each wheel of an electric ~ehicle such as an electric wheelchair ox an electric automobile. The reducer is housed inside the substantially cylindrical central hub 2 of a vehicle wheel 65. Such hub is rotatably mounted on a nonrotatable axle 66 having an axial bore 67. The output shaft of a high-speed electric motor 68 mounted stationarily relative to the axle extends through the axle bore and serves as the input shaft 6' of the reducer. The inner end portion of such shaft carries the input sun 11. There is no output shaft, bu-t rather the output sun 12 is fixed to a side of hub 2. The reaction sun 13 is fixed to the inner end portion of axle 66. All of the suns are coaxial.
A carrier disc ~1 is journaled on the axle and is freely rotatable relative thereto. Such carrier disc carries a planet shaft 20 extending parallel to the primary axis of the reducer and having an input planet 22, an output planet 23 and a reaction planet 24 in radial ali~nment with their xespective suns. The planets are connected to the suns by endless loop force-transmitting elements 25, 26 and 27. As in the previous embodiments, all of the planets rotate con~ointl~.
The operation of the embodiment of Figure 13 is substantially the sa~e as the operation o~ the embodiment of Figures 1 and 2. Rotation o$ the input sun 11 by rotation of the m~to~ oukput shaft effects rotation of the wheel hub 2 and wheel 65 relati~e to the nonrotatable axle 66 carrying the reaction sun.
The velocity ratio of the embodiment of Figure 13 can be changed by removing the output endless loop force-transmittiny element 23, so that there is no force transference between the output planet and sun, and fixing carrier disc 41 to hub 2.
In this instance, the wheel 65 rotates at the same speed as the speed of rotation of the carrier disc, which is faster than the speed of rotation of the output sun 12 with belt 23 connected and the carrier disc free to rotate relative to the hub. Speed shift mechanism, similar to the embodiment of Figures 6 and 7, can be incorporated to select between the two types of operation. Rather than being fixed to an end of the hub, output sun 12 can be rotatable relative to the hub, and a brake or lock provided -to prevent or allow rotation of the output sun relative to the hub.
A further brake or lock $or the carrier disc would be required to prevent rotation of the carrier disc relative to the hub when the output sun is rotatable and to allow rotation of the carrier disc rela-tive to the hub when the output sun is fixed.
~l.5~9~3~
Figure 14 illustrates a "drum motor" applica~
tion using an electric motor and a speed reducer in accordance with the present invenkion in which the high-speed electric motor 69 is mounked inside a cylindrical drum 2, such as a roller drum or a drum dri~ing a belt conveyor. Such drum has opposite end discs 70 and 71. Motor 69 is mounted inside the drum by a mounting sleeve 72 rotatably recelved in an aperture through the center of drum end disc 70. As diagrammatically illustrated at -the right of Figure 14, the motor mounting sleeve is rigidly attached to the frame 72 on which the drum motor is mounted for preventing rotation of the electric motor~ The power connection 74 for the motox e~tends lengthwise through the axial bore of the stationary mounting sleeve 72.
The rotating motor output shaft extends axially of the drum 2 toward drum end disc 71 and serves as the input shaft 6" of the reducer. The free end portion of the input shaft is received in a bore in the inner end of a reaction shaft 75 rotatably mounted in a central aperture in end disc 71. The input sun 11 rotates with input shaft 6"; the output sun 12 is fixed to the inner side of end disc 70; and the reaction sun 13 is fixed to the inner end portion : of reaction shaft 75.
An idler carrier disc 41 is rota$ably mounted on sleeve 75 and supports a planet shaft 20 extending parallel $o the primary axis o~ the reducer and carrying an input planet 22, an output planet 23 and a reaction planet 24 radially aligned with their respective suns. Corresponding suns and planets are connected by endless loop force-transmitting elements 25, 26 and 27.
As diagrammatically illustrated at the left of Figure 14, a brake 76 carried by the stationary frame 73 supporting the drum motor normally is clamped for preventing rotation of reaction shaft 75 and reaction sun 13 relative to the frame. Rotation of the input sun 11 by rotation of shaft 6" effects rotation of all of the planets conjointly, and rotation of the reaction planet 24 effects rotation o-f the entire carrier assembly around the stationary .reaction sun 13. Rotation and orbiting of the output planet 23 effects rotation of the output sun 12, and the drum to which it is attached, relative to the frame. The drum-driving engagement of the input sun 11 wi-th the output sun 12 can be disconnected by releasing brake 76 for allowing rotation of the reaction sun relative to -the frame~
In each embodiment of the invention, the suns and planets of the epicyclic speed reducer are connected by endless loop force-transmitting elements, and input power is transferred directly to a planet shaft supported b~ an idler carrier member, permitting hiyh input speed and easy adjustment of the velocity ratio of the reducer by substitution of one planet or sun for another~
Such two shafts can be directly connected by a coupling 32.
Alternatively r as shown in Figure 4, the housing input end disc 3 can have outward projecting mounting brackets 33 spaced on opposite sides o~ the input shaf-t 6 such that a flange frame motor 34 can be stationarily mounted on such brackets with its output shaft 35 in registration with the speed reducer input shaft 6 and connected to such input shaft by a coupling 36.
For very high speed or high torque applications, it is preferred that the carrier assembly be balanced, that is, have its center of gravity on the primary axis. In the duplex carrier assembly shown in Fiyure 5, two sets of planets are carried, respectively, by two separate planet sha~ts 20 journaled in opposite end portions o~ the carrier plates 16 by bearings 17.
Each set o planets includes an input planet 22, an output planet 23 and a reaction planet 24, each o the same size as the corresponding planet of the other set. The input shaft 6 carries two identical input suns ll side-by-side between the carrier plates. ~ach input sun is radially aligned with one o the input planets and is connected thereto by an endless loop force-transmitting element 25. A single endless loop force-transmitting element 27 operahly connects the two reaction planets 24 and the reaction sun 13.
Similarly, a single endless loop force-transmitting element would connect the two output planets 23 and the output sun (not shown). In other respects, the embodiment of the present invention shown in Figure 5 is identical to the embodiment shown in Figures 1 and 2. While two sets o~ planets are shown in Figure 5, three or more sets could be provided, preferably spaced uniformly circumferentially around the primar~
axis of the reducer.
The embodiment o the present invention shown in Figures 6 and 7 al~o uses a substantially cylindrical housing 2 h~ving opposite input and output end discs 3 and 4, respectively. Rather than being ; fixed to the input end disc, the reaction sun 13 is fixed on a sleeve 37 journaled in a bearing 38 carried in an aperture through the center of the input end disc. A brake disc 39 also is ~ixed to the sleeve, but outside of the housing, and a clamping brake mechanism 40 is provided to clamp or release the brake disc, thereby resistin~ rotation of the reaction sun or permitting it to rotate Ereely.
The input sha~t 6 of such reducer extends through the bore of sleeve 37 and, as in the previous embodiments, has its inner end portion received in a bearing lO carried in a blind axial bore in the inner end of vutput shaft 8 extending through the housing output end disc 4. The input sun 11 carried by the input shaft is connected to the input planet 22 carried by the planet shaft 20 b~ an endless loop force-transmitting element 25. Such planet shaft is supported for orbiting about the primary axis of the reducer by an idler carrier disc 41 journaled on sleeve 37 by a bearing 42 and freely rotatable relative to such sleeve. A suitable fastener, such as a nut, at the inner end portion o~ slee~e 37 prevents sliding of the carrier disc axially of such sleeve. The output planet 23 and the reaction planet 24 are carried at the opposite end portions of the planet shaft 2~ in radial alignment with their corresponding output and reaction suns 12 and 13, respectively, and are connected to such suns by endless loop force-transmitting elements 26 and 27, respectively.
A further modi~ication of the embodiment shown in ~igures 6 ancl 7 is the provision of a clamping brake mechanism 43 for the idler carrier disc 41.
Such brake is carried at the inner periphery of housing 2 and is actuatable to securely clamp the carrier disc, and thereby pre~ent its rotation, and is releasable for allowing free rotation of the caxrier disc.
1~
In use, with brake 40 ac-tuated for preventing rotation of the brake disc 39 and the reaction sun 13, and with brake 43 released ~or permitting free rotation of the carrier disc, the embodiment o~ Figure 7 operates the same as the embodiment of Figures l and ~. ~owever, the speed reducer o~ Figure 6 can be converted from epicyclic to ordinary operation by simultaneously releasing brake 40 for permitting free rotation of the reaction sun and applying brake 43 for preventing rotation of the carrier disc. In this instance, the primary and secondary axes o~ the reducer remain stationary relative to each other and the reducer acts as a two-stage ordinary speed reducer. The velocity ratio is the product of the ratios of the input and output sets, that is, the product of N22/Nll and Nl2/N23. Thls product will be several times less than the velocity ratio in epicyclic operation.
Brake 40 and brake disc 39 also can be used in cooperation to determine the maximum output torque transferable by output shaft ~. With brake 43 released, the frictional resistance applied by brake 40 to the brake disc can be selected at any desired ~alue so that the reaction sun will slip if the applied torque exceeds a predetermined value. This would be beneficial, for example, if the load driven by the output shaft becomes jammed, preventin~ rotation of the output shaft, whereupon the brake disc would slip in its brake and permit rotation of the reaction sun before the reducer or the motor drivin~ the input shaft is damaged.
Brake 40 and brake disc 39 also can be used in cooperation for ~radual, as opposed to instantaneous, "3~
start-up. As discussed above, the present in~ention permits us~ of light, inexpensive high-speed electric motors for driving input shaft 6. It can take such a motor a substantial period to reach its designed operating speed, and if a substantial load is applied immediately, the motor coulcl stall before the operatiny speed is reached. With bra~e 43 released ~or allowing free rotation of the carrier disc 41 and with brake 40 released enabling free rotation of brake disc 39 and reaction sun 24, e~en if a substantial load is applied to the output shaft, very little torque need be applied to the input sha~t to start the carrier member revolving because the reaction sun is free to rota-te. As the motor reaches its designed output speed, brake 40 can be applied gradually, whereupon the output shaft begins to turn, until finally the brake is fully applied resulting in the reaction sun heing held stationary relative to the housing and the output shaft being rotated at maximum speed in epicyclic operation.
The embodiment of the present invention shown in Figures 8 and 9 is ~ery similar to the embodi-ment shown in Figures 6 and 7, the major differences being that the reaction sun 13 in Figures 8 and 9 is fixed to the housing input end disc 3 and is of variable effecti~e circumferential extent for changing the velocity ratio of the reducer. ~s best seen in Figure 9, the reaction sun 13 includes a central core portion 45 surrounded by a somewhat resilient annular outer strip 46. The adjacent ends of the annular strip do not abut, but rather define a narrow ~ap 47 at the top of the reaction sun. ~uch ends are movable toward and away from each other for reducing or increasiny the effective circumferential extent of the reaction sun by manually turning a worm 48 meshing with a worm gear 49 formed integral with a sleeve nut 50. The sleeve nut, serving as a turnbuckle, receives oppositely threaded screws 51 projecting from plates 52 rigidly attached to the innex peripheries of the opposite end portions of the annular strip 46.
Rotation of worm gear ~9 in one direction will reduce the effective size of the reaction sun while rotation of the worm gear in the opposite direction will increase the effective size of the sun. As previously discussed, even a slight change in the effective size of the reaction sun effects a substan-tially change in the velocity ratio of the reducer.
As shown in Figure 9, an idler pulley 53 can be provided to tension the reaction endless loop force-transmitting element 27 despite changes in the effective size of the reaction sun.
As shown in Figure 10, the modifications of Figures 6 and 7 and Figures 8 and 9 can be combined.
The embodiment of Figure 10, like the embodiment of Figures 6 and 7, has a brake disc 39 and reaction sun 13 both fixed to a sleeve 37 rotatably mounted in the housing input end disc 3. The construction of the reaction sun of the embodiment of Figure 10 is substan-tially identical to the construction of the reaction sun in Figures 8 and 9, with the exception that an electric motor 54 is provided for turning worm 48 to adjust the effective circumferential extent of the reaction sun. Power to the electric motor 5~ is supplied through slip rings 55. Accordingly, the velocity ra~io of the spee~ reducer can be adjusted from a remote location for speed control of the output shaft.
The embodiment o~ the present invention shown in Figure 11 has two reaction suns 13' and 13l' in side-by-side arrangement, each ha~ing its own associated brake disc 39' or 39". The diameters of the two reaction suns are slightly different. The reaction sun 13' adjacent to the housing input end disc 3 is fixed to a sleeve 56 carrying the clutch disc 3~' and extending through the central aperture in such end disc. The other ~eaction sun 13" is fixed to a sleeve 58 extending through the bore of sleeve 56 and carrying the other brake disc 39". Both sleeves are freely rotatable relative to each other and relati~e to the housing input end disc.
The planet shaft 2~ carried by the idler carrier assembly (not shown) has two reaction planets 24' and 24" connected to their corresponding reaction suns by endless loop f~rce-transmitting elements 27' and 271lo Separate brakes (not shown) are provided for the two brake discs. In all other respects, the embodiment of Figure 11 is identical to the embodiment of Figures 6 and 7.
In operation, one or the other of the brake discs is fixed by actuation o~ its associated brake for maintaining the corresponding reaction sun stationary while the other brake disc and reaction sun are free to rotate. Accordingly, either of two velocity ratios can be selected depending on which brake disc and reaction sun are maintained stationary.
~l~L5~Z
Figure 12 illustrates a "nonre~erte~" embodi-ment of the present invention, that is, an embodiment in which the input and output members are not coaxial, using a substantially cylindrical housing 2 having opposite end discs 59 and 60. An output sleeve 8' is journaled in bearings 9' carried in an aperture throuyh the center oF end disc 60 and is freely rotatable relative to such end disc. Inside the housing, an output sun 12 is f.ixed to the output sleeve and a reaction sun 13 having a large central bore 15 recei~ing the sleeve is ~ixed to the housing end disc 60. The suns are coaxial about the axis of the output sleeve --the primary axis of the reducer. An idler carrier disc 41 is rotatably mounted on the inner end portion of the output sleeve by a bearing 42. Sliding of the carrier disc axially of the output sleeve is prevented by a fastener such as a nut 61.
A light, high-speed electric motor 62 is mounted at the outer margin of the idler carrier disc with its output shaft projecting parallel to but spaced ~rom the axis o~ output sleeve 8'. The motor shaft serves as the planet shaft 20' for the output planet 23 and the reaction planet 24 aligned, respect-ively, with output sun 12 and reaction sun 13. Such planets are fixed to the output shaft for conjoint rotation and are connected to their respective suns by endless loop force-transmitting elements 26 and 27.
Power to the electric mo~or is supplied through slip rings 55 mounted on a stationary sleeve 63 projec-ting inward from housing end disc 59 and coaxial with the output sleeve 8'. The speed reducer of Figure 12 can be conveniently mounted with a separate shaft 64 ex-tendin~ through the bores of sleeves 8' and 63, which shaft can be stationary or movable without interferring wi-th operation o~ the reducer. ~lterna-tively, output sleeve 8' can have internal threads complemental to external threads of shaft 64, and sha~t 64 can be nonrotatable, such that rotation of the output sleeve moves shaft 64 axially through the reducer.
In operation, rotation of reaction planet 2 by rotation of the motor output shaft 20' effects rotation of the entire carrier assembly, including the motor, about the stationary reaction sun 13. Rotation of output planet 23 about the axis of the motor output shaft and orbitin~ of such planet about the primary axis of the reducer effects rotation of output sun 12 and output shaft 8' carr~ing such sun. The velocity ratio R of the speed reducer, that is, the rotative speed of the motor output shaft acting as the planet sha~t 20' as compared to the rotative speed of output shaft 8' can be shown to be represented by the following equation:
R 1 Nl3N23 If the t~o planets are the same size, each havin~ "x"
teeth, and the relative numbexs o~ teeth of the reaction planet 24 and the reaction sun 13 is 1:8, or lx:8x, the velocity ratio equation can be reduced to the following:
1 ~ x .~ 7 R ~ - N 3x = N~3 xN12 12 This equation is the same a~; the reduced equation for the embodiment of Figures 1 and 2. Accordin~lY, if the output sun is a co~ wheel having 150 teeth and the reaction sun is a cog wheel having 151 teeth, the velocity ratio is 1,050:1.
Figure 13 illustrates an "electric wheel"
application using an electric motor and a speed reducer in accordance with the present invention for drivin~ each wheel of an electric ~ehicle such as an electric wheelchair ox an electric automobile. The reducer is housed inside the substantially cylindrical central hub 2 of a vehicle wheel 65. Such hub is rotatably mounted on a nonrotatable axle 66 having an axial bore 67. The output shaft of a high-speed electric motor 68 mounted stationarily relative to the axle extends through the axle bore and serves as the input shaft 6' of the reducer. The inner end portion of such shaft carries the input sun 11. There is no output shaft, bu-t rather the output sun 12 is fixed to a side of hub 2. The reaction sun 13 is fixed to the inner end portion of axle 66. All of the suns are coaxial.
A carrier disc ~1 is journaled on the axle and is freely rotatable relative thereto. Such carrier disc carries a planet shaft 20 extending parallel to the primary axis of the reducer and having an input planet 22, an output planet 23 and a reaction planet 24 in radial ali~nment with their xespective suns. The planets are connected to the suns by endless loop force-transmitting elements 25, 26 and 27. As in the previous embodiments, all of the planets rotate con~ointl~.
The operation of the embodiment of Figure 13 is substantially the sa~e as the operation o~ the embodiment of Figures 1 and 2. Rotation o$ the input sun 11 by rotation of the m~to~ oukput shaft effects rotation of the wheel hub 2 and wheel 65 relati~e to the nonrotatable axle 66 carrying the reaction sun.
The velocity ratio of the embodiment of Figure 13 can be changed by removing the output endless loop force-transmittiny element 23, so that there is no force transference between the output planet and sun, and fixing carrier disc 41 to hub 2.
In this instance, the wheel 65 rotates at the same speed as the speed of rotation of the carrier disc, which is faster than the speed of rotation of the output sun 12 with belt 23 connected and the carrier disc free to rotate relative to the hub. Speed shift mechanism, similar to the embodiment of Figures 6 and 7, can be incorporated to select between the two types of operation. Rather than being fixed to an end of the hub, output sun 12 can be rotatable relative to the hub, and a brake or lock provided -to prevent or allow rotation of the output sun relative to the hub.
A further brake or lock $or the carrier disc would be required to prevent rotation of the carrier disc relative to the hub when the output sun is rotatable and to allow rotation of the carrier disc rela-tive to the hub when the output sun is fixed.
~l.5~9~3~
Figure 14 illustrates a "drum motor" applica~
tion using an electric motor and a speed reducer in accordance with the present invenkion in which the high-speed electric motor 69 is mounked inside a cylindrical drum 2, such as a roller drum or a drum dri~ing a belt conveyor. Such drum has opposite end discs 70 and 71. Motor 69 is mounted inside the drum by a mounting sleeve 72 rotatably recelved in an aperture through the center of drum end disc 70. As diagrammatically illustrated at -the right of Figure 14, the motor mounting sleeve is rigidly attached to the frame 72 on which the drum motor is mounted for preventing rotation of the electric motor~ The power connection 74 for the motox e~tends lengthwise through the axial bore of the stationary mounting sleeve 72.
The rotating motor output shaft extends axially of the drum 2 toward drum end disc 71 and serves as the input shaft 6" of the reducer. The free end portion of the input shaft is received in a bore in the inner end of a reaction shaft 75 rotatably mounted in a central aperture in end disc 71. The input sun 11 rotates with input shaft 6"; the output sun 12 is fixed to the inner side of end disc 70; and the reaction sun 13 is fixed to the inner end portion : of reaction shaft 75.
An idler carrier disc 41 is rota$ably mounted on sleeve 75 and supports a planet shaft 20 extending parallel $o the primary axis o~ the reducer and carrying an input planet 22, an output planet 23 and a reaction planet 24 radially aligned with their respective suns. Corresponding suns and planets are connected by endless loop force-transmitting elements 25, 26 and 27.
As diagrammatically illustrated at the left of Figure 14, a brake 76 carried by the stationary frame 73 supporting the drum motor normally is clamped for preventing rotation of reaction shaft 75 and reaction sun 13 relative to the frame. Rotation of the input sun 11 by rotation of shaft 6" effects rotation of all of the planets conjointly, and rotation of the reaction planet 24 effects rotation o-f the entire carrier assembly around the stationary .reaction sun 13. Rotation and orbiting of the output planet 23 effects rotation of the output sun 12, and the drum to which it is attached, relative to the frame. The drum-driving engagement of the input sun 11 wi-th the output sun 12 can be disconnected by releasing brake 76 for allowing rotation of the reaction sun relative to -the frame~
In each embodiment of the invention, the suns and planets of the epicyclic speed reducer are connected by endless loop force-transmitting elements, and input power is transferred directly to a planet shaft supported b~ an idler carrier member, permitting hiyh input speed and easy adjustment of the velocity ratio of the reducer by substitution of one planet or sun for another~
Claims (25)
1. A compound epicyclic speed reducer comprising:
a frame;
a reaction sun;
means for maintaining said reaction sun stationary relative to said frame;
an output sun coaxial with said reaction sun, the common axis of said two suns defining a primary axis;
at least two planets, one for each of said suns, including a reaction planet and an output planet;
planet shaft means for carrying said planets for conjoint rotation;
an idler carrier assembly rotatably supporting said planet shaft means spaced from and extending sub-stantially parallel to said primary axis, the axis of said planet shaft means supported by said idler carrier assembly defining a secondary axis;
at least two endless loop force-transmitting elements connecting, respectively, said reaction sun and said reaction planet, and said output sun and said output planet; and rotary input means for driving said planet shaft means and thereby effecting conjoint rotation of said two planets about said secondary axis, rotation of said reaction planet effecting rotation of said idler carrier assembly about said primary axis for orbiting of said planet shaft means and said planets about said primary axis, and rotation of said output planet about said secondary axis in combination with orbiting of said output planet about said primary axis effecting rotation of said output sun.
a frame;
a reaction sun;
means for maintaining said reaction sun stationary relative to said frame;
an output sun coaxial with said reaction sun, the common axis of said two suns defining a primary axis;
at least two planets, one for each of said suns, including a reaction planet and an output planet;
planet shaft means for carrying said planets for conjoint rotation;
an idler carrier assembly rotatably supporting said planet shaft means spaced from and extending sub-stantially parallel to said primary axis, the axis of said planet shaft means supported by said idler carrier assembly defining a secondary axis;
at least two endless loop force-transmitting elements connecting, respectively, said reaction sun and said reaction planet, and said output sun and said output planet; and rotary input means for driving said planet shaft means and thereby effecting conjoint rotation of said two planets about said secondary axis, rotation of said reaction planet effecting rotation of said idler carrier assembly about said primary axis for orbiting of said planet shaft means and said planets about said primary axis, and rotation of said output planet about said secondary axis in combination with orbiting of said output planet about said primary axis effecting rotation of said output sun.
2. A speed reducer as defined in claim 1, in which the input means includes an input sun coaxial with the reaction sun and the output sun, an input planet carried by the planet shaft means for conjoint rotation with the reaction planet and the output planet, an additional endless loop force-transmitting element connecting said input sun and said input planet and means for rotating said input sun, the effective circumferential extent of said input planet being substantially larger than the effective circum-ferential extent of said input sun such that rotation of the input sun at one speed effects rotation of said input planet at a substantially slower speed.
3. A speed reducer as defined in claim 2, in which the effective circumferential extent of the input planet is at least twice the effective circum-ferential extent of the input sun.
4. A speed reducer as defined in claim 1 or 2, in which the effective circumferential extent of the reaction sun is substantially larger than the effective circumferential extent of the reaction planet such that rotation of the reaction planet about the secondary axis at one speed effects orbiting of such planet about the primary axis at a substantially slower speed.
5. A speed reducer as defined in claim 1 or 2, in which the effective circumferential extent of the reaction sun is at least twice the effective circum-ferential extent of the reaction planet such that rotation of the reaction planet about the secondary axis at one speed effects orbiting of such planet about the primary axis at a substantially slower speed.
6. A speed reducer as defined in claim 1, in which the rotary input means includes an electric motor having an output shaft rotating at a speed of at least 3,000 rpm.
7. A speed reducer as defined in claim 1 or 6, in which the velocity ratio of the speed reducer is at least 1,000:1.
8. A speed reducer as defined in claim 1, including a plurality of sets of planets, each set of planets including a reaction planet and an output planet, and a plurality of planet shaft means each carrying one set of planets for conjoint rotation, and in which the idler carrier assembly rotatably supports the plurality of planet shaft means spaced substantially uniformly circumferentially around the primary axis, the endless loop force-transmitting elements connecting, respectively, the reaction sun and all of the reaction planets and the output sun and all of the output planets, and the rotary input means including means for driving all of said planet shaft means.
9. A speed reducer as defined in claim 1, in which the reaction sun is fixed to the frame.
10. A speed reducer as defined in claim 1, in which the reaction sun maintaining means includes brake means actuatable for maintaining the reaction sun stationary relative to the frame and releasable for allowing rotation of the reaction sun relative to the frame.
11. A speed reducer as defined in claim 10, in which the brake means includes a brake disc connected to the reaction sun and rotatable therewith and a clamping brake mechanism actuatable for resisting rotation of said brake disc relative to the frame and releasable for allowing rotation of said brake disc relative to the frame.
12. A speed reducer as defined in claim 10, including carrier brake means actuatable for preventing rotation of the idler carrier assembly about the primary axis and releasable for allowing free rotation of the idler carrier assembly about such axis.
13. A speed reducer as defined in claim 12, in which the idler carrier assembly includes a carrier disc concentric about the primary axis, and the carrier brake means includes a clamping brake mechanism actuatable for resisting rotation of said carrier disc relative to the frame and releasable for allowing free rotation of said carrier disc relative to the frame.
14. A speed reducer as defined in claim 1, in which the reaction sun is of variable effective circumferential extent for varying the velocity ratio of the speed reducer.
15. A speed reducer as defined in claim 14, in which the reaction sun includes a somewhat resilient annular outer strip forming the outer periphery of the reaction sun, and including means for expanding and contracting said annular outer strip to vary the effective circumferential extent of said reaction sun.
16. A speed reducer as defined in claim 15, in which the expanding and contracting means includes a remotely actuatable electric motor.
17. A speed reducer as defined in claim 16, in which the electric motor is mounted on the reaction sun.
18. A speed reducer as defined in claim 1 or 14, including means for tensioning the endless loop force-transmitting element connecting the reaction sun and the reaction planet.
19. A speed reducer as defined in claim 1, including a second reaction sun coaxial with the output sun, a second reaction planet carried by the planet shaft means for conjoint rotation with the other planets, an additional endless loop force-transmitting element connecting said second reaction sun and said second reaction planet and separate brake means, one for each of the reaction suns, each brake means being actuatable to resist rotation of its associated reaction sun relative to the frame and being releasable for allowing rotation of its reaction sun relative to the frame, said separate brake means being independently actuatable and releasable.
20. A speed reducer as defined in claim 19, in which each brake means includes a brake disc connected to one of the reaction suns and rotatable therewith and a clamping brake mechanism actuatable for resisting rotation of its brake disc relative to the frame and releasable for allowing free rotation of its brake disc relative to the frame.
21. A speed reducer as defined in claim 1 or 20, including a hollow output sleeve carrying the output sun and having an axial bore coaxial with the primary axis.
22. A speed reducer as defined in claim 1, including a wheel hub rotatably supported by the frame for rotation about the primary axis, the output sun being fixed to such hub, and the rotary input means including an electric motor stationary relative to the frame and mounted outside of the wheel hub, rotation of the planet shaft means by said electric motor effecting rotation of said wheel hub relative to the frame.
23. A speed reducer as defined in claim 1, including a substantially cylindrical drum supported by the frame for rotation about the primary axis, the rotary input means including an electric motor mounted inside the drum stationary relative to the frame and having a rotary output member extending substantially along the primary axis, the suns, planets and carrier assembly being carried inside the drum, and the output sun being fixed to the drum, rotation of the planet shaft means by rotation of the motor output member effecting rotation of the drum relative to the frame.
24. A compound epicyclic speed reducer comprising:
a frame;
at least two suns;
means mounting said suns on said frame in coaxial relationship, the common axis of said two suns defining a primary axis;
means for maintaining one of said suns stationary relative to said frame;
at least two planets, one for each of said suns;
planet shaft means for carrying said planets for conjoint rotation;
an idler carrier assembly rotatably supporting said planet shaft means spaced from and extending sub-stantially parallel to said primary axis, the axis of said planet shaft means supported by said idler carrier assembly defining a secondary axis;
at least two endless loop force-transmitting elements connecting, respectively, one of said suns and one of said planets, and the other of said suns and the other of said planets;
rotary input means for effecting rotation of said planet shaft means and thereby effecting conjoint rotation of said two planets about said secondary axis, rotation of said planets effecting rotation of said idler carrier assembly about said primary axis for orbiting of said planet shaft and said planets about said primary axis; and a rotary output member rotatably mounted on said frame and driven by rotation of said planets about said secondary axis in combination with orbiting of said planets about said primary axis.
a frame;
at least two suns;
means mounting said suns on said frame in coaxial relationship, the common axis of said two suns defining a primary axis;
means for maintaining one of said suns stationary relative to said frame;
at least two planets, one for each of said suns;
planet shaft means for carrying said planets for conjoint rotation;
an idler carrier assembly rotatably supporting said planet shaft means spaced from and extending sub-stantially parallel to said primary axis, the axis of said planet shaft means supported by said idler carrier assembly defining a secondary axis;
at least two endless loop force-transmitting elements connecting, respectively, one of said suns and one of said planets, and the other of said suns and the other of said planets;
rotary input means for effecting rotation of said planet shaft means and thereby effecting conjoint rotation of said two planets about said secondary axis, rotation of said planets effecting rotation of said idler carrier assembly about said primary axis for orbiting of said planet shaft and said planets about said primary axis; and a rotary output member rotatably mounted on said frame and driven by rotation of said planets about said secondary axis in combination with orbiting of said planets about said primary axis.
25. Rotary drive mechanism comprising a high-speed electric motor having a rotary output member rotating at a speed of at least 3,000 rpm, and a compound epicyclic speed reducer having a velocity ratio of at least 1,000:1 and including: an input shaft rotatable about a first axis by rotation of said motor rotary output member; an output shaft coaxial with the input shaft and rotatable relative thereto; three suns, all concentric about said first axis, including a stationary reaction sun, an input sun rotatable with said input shaft and an output sun rotatable with said output shaft; three planets, including a reaction planet for said reaction sun, an input planet for said input sun and an output planet for said output sun; planet shaft means carrying said three planets for conjoint rotation;
an idler carrier member mounting said planet shaft means spaced from and extending substantially parallel to said first axis for orbiting of said planet shaft means about the primary axis; and three endless loop force-transmitting elements for connecting, respectively, said reaction sun and said reaction planet, said input sun and said input planet, and said output sun and said output planet.
an idler carrier member mounting said planet shaft means spaced from and extending substantially parallel to said first axis for orbiting of said planet shaft means about the primary axis; and three endless loop force-transmitting elements for connecting, respectively, said reaction sun and said reaction planet, said input sun and said input planet, and said output sun and said output planet.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US121,987 | 1980-02-15 | ||
| US06/121,987 US4321842A (en) | 1979-02-19 | 1980-02-15 | Compound epicyclic cog belt speed reducer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1154982A true CA1154982A (en) | 1983-10-11 |
Family
ID=22399903
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000350347A Expired CA1154982A (en) | 1980-02-15 | 1980-04-22 | Compound epicyclic cog belt speed reducer |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1154982A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017009759A1 (en) * | 2015-07-13 | 2017-01-19 | Fondazione Istituto Italiano Di Tecnologia | Rotational speed reducer |
| CN114112379A (en) * | 2021-11-19 | 2022-03-01 | 中国直升机设计研究所 | Method for quickly replacing fault test piece at output end of main speed reducer without deviation |
| EP4040015A1 (en) | 2021-02-09 | 2022-08-10 | Alfredo Tampieri | Compact epicyclic gearing |
-
1980
- 1980-04-22 CA CA000350347A patent/CA1154982A/en not_active Expired
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017009759A1 (en) * | 2015-07-13 | 2017-01-19 | Fondazione Istituto Italiano Di Tecnologia | Rotational speed reducer |
| US10539206B2 (en) | 2015-07-13 | 2020-01-21 | Fondazione Istituto Italiano Di Technologia | Rotational speed reducer |
| EP4040015A1 (en) | 2021-02-09 | 2022-08-10 | Alfredo Tampieri | Compact epicyclic gearing |
| CN114112379A (en) * | 2021-11-19 | 2022-03-01 | 中国直升机设计研究所 | Method for quickly replacing fault test piece at output end of main speed reducer without deviation |
| CN114112379B (en) * | 2021-11-19 | 2023-05-23 | 中国直升机设计研究所 | Quick and unbiased main speed reducer output end fault test piece replacement method |
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