Multimode infinitely variable transmission

A multimode infinitely variable traction roller transmission including a toroidal traction roller transmission for infinitely varying the transmission ratio in each of the modes. Power is transmitted from an input shaft to the planet carrier of a planetary transmission whose ring is associated with the output shaft of the transmission and through the toroidal traction roller transmission to the sun of the planetary transmission selectively by way of a chain gear or spur gear transmission provided with clutches for selective engagement thereof, that is, for rotation of the sun in one or the opposite direction. A brake structure is provided for locking the planet carrier in one of the transmission modes. Output shaft speed is increased by increasing output speed of the infinitely variable transmission in the first mode (direct mode), it is further increased by subsequently decreasing the output speed of the infinitely variable transmission in the second mode (inverse regeneration mode) and it is then further increased by again increasing the output speed of the infinitely variable transmission in the third mode (split torque mode). The changeover is smooth thereby providing for a wide ratio range infinitely variable transmission.

BACKGROUND OF THE INVENTION 
The present invention relates to an infinitely variable traction roller 
transmission for the transmission of power over a large transmission ratio 
range. 
Infinitely variable transmissions have generally a relatively limited ratio 
range and a limited torque transmission capability. Partly as a result of 
this they are not used in connection with large cars or trucks. Trucks 
require a full power transmission load capability at very low speeds, for 
example, when climbing a mountain road since, for their large weight, they 
have relatively small engines of relatively low power output and yet, at 
long level road stretches, they reach high speeds. A large transmission 
ratio range is therefore needed to provide sufficient torque at the drive 
wheels at start up or during climbing and to avoid engine overspeed at 
high vehicle travel speeds. 
It is also important that trucks operate efficiently, that is, at optimum 
engine speed independently of the vehicle speed. An infinitely variable 
transmission would therefore be most desirable. Unfortunately no rugged 
infinitely variable transmissions with large transmission ratio range are 
in existence. 
Infinitely variable transmissions and more specifically infinitely variable 
traction roller transmissions are well known. Those with which the present 
invention is concerned are generally of the type as shown, for example, in 
applicant's U.S. Pat. No. 4,086,820 of May 2, 1978, or in applicant's U.S. 
Pat. No. 4,702,118. However, in order to accommodate the power as needed 
in connection with trucks, such transmissions would have to be large and 
heavy and they would require additional mechanical gear shift 
transmissions in order to achieve the needed transmission ratio ranges. 
It is therefore the principal object of the present invention to provide an 
infinitely variable traction roller transmission which is relatively small 
but capable of handling the power for driving heavy trucks at low and high 
truck operating speeds at optimum engine speed. 
SUMMARY OF THE INVENTION 
In a multimode infinitely variable traction roller transmission which has 
coaxial input and output shafts and a parallel transmission shaft 
supported in a housing in spaced parallel relationship from the input and 
output shafts but for rotation with the input shaft, the parallel shaft 
includes two infinitely variable transmission structures with outer toric 
discs mounted on the parallel shaft and inner toric discs mounted on 
opposite ends of a hollow first shaft through which the parallel shaft 
extends and which carries a chain and a spur gear each operatively engaged 
with corresponding chain and spur gears disposed on a second hollow shaft 
which is coaxial with the input and output shafts and which carries the 
sun of a planetary type transmission whose ring is associated with the 
transmission output shaft and whose planet carrier is mounted on one end 
of an intermediate shaft which extends through the second hollow shaft and 
at its other end carries the clutch bell of a first clutch structure for 
engagement with the input shaft. The clutch bell is also provided with a 
brake structure for locking the intermediate shaft and the planet carrier 
when the first clutch structure is disengaged. Second and third clutch 
structures are associated with the chain and spur gears preferably on the 
second hollow shaft for selectively coupling the second hollow shaft and 
the sun associated therewith for rotation in the same or the opposite 
direction of the first hollow shaft. 
The speed of the first hollow shaft with respect to the input shaft is 
infinitely variable by the infinitely variable traction roller 
transmission structures and the transmission is furthemore operable in 
three forward modes and one reverse mode. At one end of the ratio range of 
the infinitely variable transmission structure a switchover from one mode 
to the next provides for continuous infinite ratio change while moving the 
transmission ratio back to the other end of the ratio range so that 
continuously infinitely variable transmission ratio variations can be 
achieved over a large range, that is, over all three modes. It is also 
noted that in the two higher speed modes only a portion of the power 
passes through the infinitely variable transmission structures which keeps 
wear to a minimum.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The traction roller transmission as shown in FIG. 1 has an input shaft 1 
and an output shaft 2 supported in a housing 3 in axial alignment with one 
another; a parallel shaft 4 is rotatably supported in spaced parallel 
relatonship from the input and output shafts 1 and 2. The input shaft 1 
has a spur gear 5 mounted thereon which is in engagement with a spur gear 
6 mounted on the parallel shaft 4 for rotation therewith. The parallel 
shaft 4 has two infinitely variable toroidal traction roller transmission 
structures 7 and 8 associated therewith. Both are identical and generally 
of the type as described, for example, in applicant's earlier application 
Ser. No. 259,043 of Oct. 17, 1988. Transmission structures 7 and 8 have 
toric discs 9 and 11, and 12 and 10 arranged opposite one another so as to 
define toric cavities 15 and 16 therebetween in which motion transmitting 
traction rollers 17 and 18 are pivotally supported in engagement with the 
toric discs so as to be able to transmit motion therebetween at a 
transmission ratio which depends on the pivot position of the traction 
rollers 17 and 18. 
Toric discs 9 and 10 are both mounted for rotation with the parallel shaft 
4 and the toric discs 11 and 12 are both mounted on a first hollow shaft 
19 which is disposed between the infinitely variable toric transmission 
structures 7 and 8 and through which the parallel shaft 4 extends. The 
transmission structure arrangement and its operation is described in 
greater detail in applicant's application Ser. No. 259,043 mentioned 
before. It is noted nevertheless that the arrangement permits infinite 
variation of the transmission ratio between the parallel shaft 4 and the 
hollow shaft 19 which rotates in a direction opposite to that of the 
parallel shaft 4 over a predetermined ratio range. 
The hollow shaft 19 is rotatably supported by ball bearings 13 and 14 and 
is provided with a chain gear 32 and spur gear 33 for transmitting power 
to the output shaft depending on the power transmission mode. 
The input shaft 1 is provided at its inner end with a first clutching 
structure C1 which includes a clutch plate carrier 21 mounted on the input 
shaft 1 and a clutch bell 22 mounted, by way of a mounting plate 23, for 
rotation with an intermediate shaft 24 which is supported at its opposite 
ends on, and extends between, the input shaft 1 and the output shaft 2. A 
plurality of clutch plates 25, 26 are arranged between the clutch bell 22 
and the clutch plate carrier 21, alternately in engagement with one and 
the other, and a piston 27 is disposed in the clutch bell 22 and adapted 
to force the clutch plates 25 and 26 into firm engagement with one another 
against the force of a spring 28 when transmission of power through the 
clutch is desired. A brake band 29 extends around the clutch bell for 
engagement therewith when the clutch bell 22 and the intermediate shaft 24 
are to be locked. The intermediate shaft 24 extends through a second 
hollow shaft 30 which has two clutch structures associated therewith, a 
chain gear (second) clutch structure C2 and a spur gear (third) clutch 
structure C3. The chain gear clutch structure C2 is disposed in a chain 
gear 36 which is rotatably supported on a housing wall 37 by roller 
bearings 38, 39 and which is in power transmitting engagement with the 
chain gear 32 of the first hollow shaft 19 by way of a chain 40. The spur 
gear clutch structure C3 is disposed in a spur gear 41 which is rotatably 
supported on the housing wall 42 by way of ball bearing 43. The chain gear 
clutch structure C2 includes a clutch support plate 44 which is keyed to 
the second hollow shaft 30 by keys 45 and the spur gear clutch structure 
includes a clutch support plate 46 which is integral with the second 
hollow shaft 30. Both clutch structures have clutch discs alternately 
mounted on the respective clutch discs and the respective chain gear and 
spur gear with a clutch engagement member 47 disposed therebetween. The 
clutch engagement member 47 is formed integral with an operating piston 48 
disposed in a cylinder 49 so that the engagement member 47 can be forced 
hydraulically in one direction to engage the clutch structure C2 in the 
chain gear 36 so as to operatively engage the chain gear 36 with the 
second hollow shaft 30 for rotation thereof with, and in the same sense 
as, the first hollow shaft 19, and in the opposite direction for 
engagement of the clutch structure C3 in the spur gear 41 so as to 
operatively engage the spur gear 41 with the second hollow shaft 30 for 
rotation thereof with, and in a sense opposite to that of, the first 
hollow shaft 19. Hydraulic fluid passages are provided in the housing 
walls and in the shafts but they are not shown in full detail to simplify 
the drawing. Also the clutch structures C2 and C3 are normal clutches and 
therefore do not need to be explained in detail. 
Keyed to the hollow shaft 30 for rotation therewith is a sun roller 50 
which forms the center roller of a planetary type traction roller 
transmission of the type disclosed in applicant's U.S. Pat. (Ser. No. 
07/188,132). 
The planetary traction roller transmission includes a traction ring 51 
which is mounted for rotation with the transmission output shaft 2 and has 
a race 52 spaced from the surface of the sun roller 50, with planetary 
rollers 53 being disposed in the annular space between the traction ring 
51 and the sun roller 50. The planetary rollers 53 are supported by a 
carrier 54 which is firmly mounted on the other end of the intermediate 
shaft 24. 
The planetary carrier 54 is either rotated together with the input shaft 1, 
when the clutch structure C1 is engaged, or it is locked non-rotatable 
when the clutch structure C1 is disengaged and the brake band 29 engages 
the clutch bell 22. 
If the clutch structure C2 is engaged, the clutch structure C3 is 
disengaged and the sun roller rotates in the same direction as the input 
shaft rotates but at a relative speed which is variable depending on the 
ratio position of the toroidal traction roller transmission structures 7 
and 8. If the clutch structure C3 is engaged, the clutch structure C2 is 
disengaged and the sun roller rotates in a direction opposite to that of 
the input shaft and at a relative speed which is variable depending on the 
ratio position of the toroidal traction roller transmission structures 7 
and 8. Obviously the arrangement permits a variety of operating modes: The 
sun roller 50 may rotate in either direction and the traction roller 
carrier 54 may either be locked or it may be rotated together with the 
input shaft 1, all while the sun roller speed--in either direction--is 
variable relative to the input shaft speed. 
The arrangement provides for various modes of operation which are explained 
on the basis of FIGS. 2, 3, 4 and 5 in which the power flow through the 
transmission is schematicaly shown: The first forward mode as shown in 
FIG. 2 is a direct mode in which clutch C1 is disengaged and the brake 
band 29 locks the intermediate shaft 24 and the planetary traction roller 
carrier 54. Clutch C2 is disengaged and clutch C3 is engged so that the 
sun 50 rotates in a direction opposite to that of the input shaft 1 at a 
relative speed controlled by the toroidal traction roller transmission 
structures 7 and 8. The sun 50 transmits its motion through the planetary 
rollers 53 to the traction ring 51 and the output shaft 2 which rotates in 
the same direction as the input shaft 1 but at lower speed. 
The path of power is from the input shaft 1 through the spur gears 5 and 6 
to the parallel shaft 4 and through the toroidal traction roller 
transmission structures 7 and 8 over the hollow shaft 19 through clutch C3 
to the hollow shaft 30 and sun 50 and finally through the planetary 
traction rollers 53 to the traction ring 51 and the output shaft 2. 
The second forward mode as shown in FIG. 3 is called inverse regeneration 
mode: Here the clutch C1 is engaged and the brake 29 is released so that 
the intermediate shaft 24 and the planetary traction roller carrier rotate 
together with the input shaft 1. The clutch C2 is engaged and the clutch 
C3 is disengaged so that the sun rotates in the same direction as the 
input shaft at a relative speed which is variable by the toroidal traction 
roller transmission. If the sun rotates at the same speed as the input 
shaft, the planetary rollers 53 are stationary with respect to the sun and 
the traction ring and the output shaft 2 rotate at the same speed as the 
input shaft. The transmission ratio is variable so that the output shaft 
speed varies around the input shaft speed. The path of power is from the 
input shaft 1 through clutch C1, through the intermediate shaft 24 and the 
planetary roller carrier 54 and planetary rollers 53 to the traction ring 
51 and the output shaft 2. Part of the power, as a result of the reaction 
torque of the planetary rollers, is returned through the sun, the 
intermediate shaft 30, chain gears 36 and 32 to the hollow shaft 19 and 
then through the toroidal traction roller transmission structures 7 and 8 
to parallel shaft 4 and through the spur gears 5 and 6 back to the input 
shaft 1 augmenting the torque through clutch C1 and intermediate shaft 24. 
However the infinitely variable toric traction roller transmission 
structures are subjected only to part of the transmitted power through the 
transmission for the adjustment of the transmission ratio. 
The third forward mode as shown in FIG. 4 is a split-torque mode. Here, 
clutch C1 is engaged and the band brake 29 is released so that the 
planetary traction rollers 53 orbit at input shaft speed. Clutch C2 is 
disengaged and clutch C3 is engaged so that the sun roller rotates in a 
direction opposite to that of the input shaft at a somewhat lower 
speed--since gear 5 is somewhat smaller than gear 41 and gear 6 is 
somewhat larger than gear 33--variable by adjustment of the toroidal 
traction roller transmission structures 7 and 8. In this mode the output 
shaft rotates at a speed higher than input shaft speed. 
The path of power is split: The first part goes through the clutch C1, the 
intermediate shaft 24 and the planetary roller carrier to the planetary 
rollers and finally the traction ring 51 to the output shaft. The second 
part passes through the spur gears 5 and 6 through the infinitely variable 
transmission structures 7 and 8 to the hollow shaft 19 and through gears 
33 and 41 and clutch C3 to the sun 50 and to the planetary traction 
rollers 53 where it joins the first part. In this mode which is used by a 
truck for example during level long-distance driving, the transmission 
components are exposed to only relatively little stress. 
The reverse mode as shown in FIG. 5 is similar to the first mode except 
that clutch C2 is engaged and clutch C3 is released so that the sun 
rotates in the same direction as the input shaft 1 and the output shaft 2 
rotates in the opposite direction. 
Such a transmission is capable of covering a large total transmission ratio 
in an infinitely variable manner by the appropriate transfer of the power 
paths and infinite variation of the transmission ratio of the infinitely 
variable traction roller transmission structures. 
The attached operational computer printout gives the transmission ratios 
across the transmission at mode changeover points. 
In this connection it is pointed out that in the first mode (FIG. 2) the 
speed of the output shaft 2 increases with increasing speed of the output 
shaft (speed of hollow shaft 19) of the infinitely variable transmission 
structures. Upon changeover to the second mode at the end of the 
transmission ratio change in the first mode when hollow shaft 19 is at its 
highest relative speed, the transmission output shaft speed further 
increases by reducing the relative speed of the hollow shaft 19 of the 
infinitely variable transmission structures until, at the lowest relative 
speed of the hollow shaft 19, a switchover is made to the third mode (FIG. 
4) in which the transmission output shaft speed is further increased by 
again changing the transmission ratio of the infinitely variable 
transmission structures for increased speed of the hollow shaft 19. As can 
be seen from the printout, the gear ratios may be so selected that, at the 
switchover points, the respective clutch members are all the same speed so 
that no speed adjustment is necessary and the respective clutches can be 
disengaged or respectively engaged instantly without jerking. The 
arrangement actually provides continuous infinite speed variation over the 
full range of the three modes. 
It is noted that the transmission has been described with a planetary type 
traction roller structure as a torque splitting or recombining structure. 
However a planetary type gear structure may be used just as well. Also the 
housing and shafts and other components all include the passages necessary 
for supplying pressurized fluid to the cylinders for the operation of the 
clutches and the brake band. The hydraulic control fluid supply control 
arrangement for the infinitely variable traction roller transmission 
structures is described in applicant's application Ser. No. 07/303,936, 
filed Jan. 30, 1989. The pressurized fluid may be supplied by external 
sources or the transmission may include a fluid pump 35 associated for 
example with the input shaft 1 as shown in FIG. 1. 
In the embodiment described pressurized fluid operated clutches C1, C2 and 
C3 have been utilized mainly because pressurized hydraulic fluid is 
available since such pressurized hydraulic fluid is utilized for the 
operation of the infinitely variable traction roller transmission 
structures 7 and 8. However other types of clutches, for example, 
electrically operated clutches of the type as used in connection with 
automotive air conditioner compressors, could be utilized in connection 
with the transmission according to the present invention.