Continuously variable speed converter for cooperative use with a fluid pump

A continuously variable speed converter is provided wherein a plurality of balls are interposed between a pair of friction discs for transmitting rotation of an input shaft to an output shaft connected with a fluid pump. A speed change mechanism is arranged to tilt the rotational axis of each of the balls in each plane, including the axis of the input shaft, to thereby change the output/input speed ratio. Disposed within a main housing carrying the input and output shafts is the fluid pump, which also serves as a pressuring means responsive to fluid delivered by itself so as to apply to the output shaft a thrust force corresponding to the pressure of the fluid, so that efficient power transmission without slippage may be provided between the friction discs and the balls.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a continuously variable speed converter 
and, more particularly, to such a converter of the friction type for 
cooperative use with a fluid pump driven by an engine of a motor vehicle. 
2. Description of the Prior Art 
In a continuously variable speed converter known heretofore, as shown in 
FIG. 1, a pair of friction discs 4 and 5 are carried respectively on 
axially aligned input and output shafts 1 and 2 and, at guide ways 4a and 
5a formed respectively thereon, are in contact with power-transmission 
balls 3, the rotational axis of each of which is angularly adjustable. 
Further, a pressuring ring 8 is keyed on each of the shafts 1 and 2 to 
define between itself and the associated disc 4 or 5 a plurality of 
circumferentially continued rhomboid grooves 7, in each of which a 
pressuring ball 6 is contained. These grooves 7 and balls 6 constitute a 
pressuring device, which serves to automatically adjust the contact 
pressure between the associated discs 4 and 5 and the power-transmission 
balls 3. Namely, when rotational torque which corresponds to the load on 
the output shaft 2 acts on the pressuring device thereof, the pressuring 
balls 6 ride up on the slopes of the grooves 7, generating a thrust force 
based upon such wedge action and, in consequence, the associated discs 4 
and 5 pressure the balls 3 to thereby adjust the contact pressure 
therebetween. 
In the speed converter, the rotational torque acting on the input shaft 1 
becomes larger than that acting on the output shaft 2 when the 
output/input speed ratio is more than 1, while rotational torque acting on 
the output shaft 2 becomes larger than that acting on the input shaft 1 
when the speed ratio is less than 1, and in order to generate thrust force 
corresponding to the larger rotational torque, therefore, such a 
pressuring device has to be provided on each of the input and output 
shafts 1 and 2. This undesirably makes the construction complicated and 
invites increases of manufacturing costs because of the difficulty in 
machining the rhomboid grooves. In addition, since the slopes of the 
rhomboid grooves 7 suffer from wear by the action of great thrust force, 
problems in maintenance remain unsolved. 
SUMMARY OF THE INVENTION 
It is therefore a primary object of the present invention to provide an 
improved speed converter incorporating a pressuring device which is simple 
in construction, is reliable in operation and is freed from notable 
functional deterioration caused by wear. 
Another object of the invention is to provide an improved speed converter 
in which contact pressure of friction engagement portions for power 
transmission is automatically adjusted by a sole pressuring device in 
adaptation to load acting on an output shaft. 
Yet another object of the present invention is to provide an improved speed 
converter of the character set forth above, capable of cooperative use 
with a fluid pump and of generating contact pressure corresponding to load 
on the pump. 
Briefly, these and other objects are achieved by the present invention 
through the provision of a continuously variable speed converter for 
cooperative use with a fluid pump which comprises a main housing, an input 
shaft rotatably carried in the main housing, an output shaft rotatably 
carried in the main housing in axial alignment with the input shaft and 
drivingly connected with the fluid pump to operate the same, a pair of 
friction discs respectively provided on the input and output shafts, a 
plurality of balls held in contact with the friction discs for power 
transmission therebetween, and holding and adjusting means for rotatably 
holding the plurality of balls and for angularly tilting the rotational 
axis of each of the balls in each plane, including the axis of the input 
shaft, so as to adjust the output/input speed ratio. 
The speed converter further comprises pressuring means for applying on one 
of the input and output shafts a thrust force corresponding to the 
pressure of fluid delivered from the pump, whereby contact pressure 
between the friction discs and the balls can be adjusted in adaptation to 
load acting on the fluid pump.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring now the drawings, wherein like reference numerals designate like 
or corresponding parts throughout the several views, and particularly to 
FIG. 2 thereof, there is shown an embodiment, in which a stepless or 
continuously variable speed converter T is incorporated in a pump device 
10 and, at its output shaft 31, is directly connected to a pump rotor 42. 
A main housing 20 is formed, in axial alignment, with an enlarged bore 21 
and a bore 22, in which the speed converter T and pump components P are 
respectively housed. The speed converter T in the enlarged bore 21 
comprises a pair of friction discs 23 and 24 formed in inner ends of the 
input and output shafts 28 and 31 in face-to-face relation with each 
other, a plurality of balls 25, shown being four in number, rolling in 
contact with guide ways 23a and 24a of the friction discs 23 and 24, a 
plurality of retaining rollers 26, also shown being four in number, 
holding the balls 25 in contact with the guide ways 23a and 24a and being 
capable of tilting the rotational axis of each of the balls 25 in each 
plane, including the axis of the input shaft 28, and a retaining case 27 
pivotably retaining support shafts 26a of the rollers 26. The input shaft 
28, protruding from the friction disc 23, is rotatably carried through a 
bearing 30 by an end cover 29 secured to one end of the main housing 20, 
being restrained from axial movement. The output shaft 31, protruding from 
the other friction disc 24, is extended into the bore 22 containing the 
pump components P and is rotatably carried by the main housing 20 through 
a bearing 32, being allowed axial movement. A pulley 11 is keyed on an 
outer end of the input shaft 28 and is driven via a V-belt by a drive 
pulley keyed on an engine rotational shaft, not shown. The output shaft 31 
is formed with a through bore 33 along its longitudinal axis, as well as 
with a spline 34 as its outer surface. 
The pump components P in the bore 22 comprise a pump casing 40 having an 
internal cam bore 40a, a pump rotor 42 mounted on the output shaft 31 
through a spline engagement and received in the cam bore 40a, a plurality 
of radially movable vanes 41 retained by the pump rotor 42 and urged to 
contact with the internal surface of the cam bore 40a, and side plates 43 
and 44 held in contact, respectively, with both side surfaces of the pump 
casing 40 and the pump rotor 42 disposed therebetween. A cap member 45 for 
closing the open end of the bore 22 is also contained within the main 
housing 20, with a pre-loaded spring 46 being interposed between itself 
and the side plate 44, and is prevented by means of a snap ring 47 from 
slipping off. A cylinder 48 containing a piston 49 is formed in the cap 
member 45 in axial alignment with the output shaft 31. The inward open end 
of the cylinder 48 snugly receives a cylindrical sleeve 50 protruding from 
the side plate 44 so as to be closed thereby. A cylindrical sleeve 45a, 
protruding from the cap member 45, is fitted into the side plate 44 to 
define a cavity 75, into which atmospheric air is introduced. The piston 
49 is connected to one end of a rod 53, which is extended into the through 
hole 33 of the output shaft 31 and which is carried by means of bushings 
51 and 52 for rotational and axial movement relative to the output shaft 
31. The other end of the rod 53 is inserted into the retaining case 27 and 
is connected to a forked member 54 engaging both side faces of the 
retaining rollers 26. A compression spring 55 is interposed between the 
forked member 54 and the retaining case 27 to urge the forked member 54 
toward the right, as viewed in FIG. 2. 
Fixed on and over the main housing 20 is an oil reservoir 60, from the 
bottom of which a tubular member 61 is extended to be inserted into a 
vertical hole 62 of the main housing 20. This tubular member 61 defines a 
suction passage which leads to a pump suction area via an annular passage 
63 formed in the housing 20 around the pump casing 40. A horizontal 
passage 64 intersecting with the vertical hole 62 allows the oil reservoir 
60 to communicate with the enlarged bore 21 containing the speed converter 
T and admits working oil into the bore 21 to effect lubrication of the 
parts of the speed converter T. The side plates 44 and 43 are formed, 
respectively, with an arc through hole 66 and an arc slot 65, which 
angularly correspond to a pump delivery area, and the hole 66 and the slot 
65 are respectively in fluid communication with a pressure chamber 67 
defined between the side plate 44 and the cap member 45 and, via a passage 
76, with another pressure chamber, not numbered, defined between the side 
plate 43 and the main housing 20. Fluid under pressure delivered into the 
pressure chamber 67 is connected to a delivery passage 68 formed in the 
housing 20, as shown in FIG. 4, so as to be supplied from an outlet 69 to 
actuators, such as a power steering device, not shown. 
A throttle 70 is formed on the delivery passage 68, and pressurized fluids 
before and behind the throttle 70 are introduced into the cylinder 48. 
Specifically, pressurized fluid in the pressure chamber 67 is introduced 
into the right chamber of the cylinder 48 via a passage 71 and pressurized 
fluid in the delivery passage 68 behind the throttle 70 is introduced into 
the left chamber of the cylinder 48 via passages 72 and 73. A pressure 
force corresponding to the pressure difference between both the 
pressurized fluids acts on the piston 49 to thereby axially displace the 
forked member 54, through the rod 53, against the spring 55, and the 
support shafts 26a of the retaining rollers are thus pivotably moved 
relative to the retaining case 27. By this, the rotational axes of the 
balls 25, which are held in contact with the retaining rollers 26 and with 
the guide ways 23a and 24a of the friction discs 23 and 24, as shown in 
FIG. 3, are angularly tilted in respective planes, each including the axis 
of the input shaft 28, and the output/input speed ratio is automatically 
controlled to maintain constant the difference between the pressures of 
fluids before and behind the throttle 70, so that pressurized fluid may be 
delivered from the outlet 69 approximately at a predetermined flow rate. 
The side plates 43 and 44 are pressured toward each other since they 
receive pump-delivered pressurized fluid at side surfaces thereof which 
are on the opposite side with respect to the other side surfaces being in 
contact with the pump rotor 42. Since the pressure receiving effective 
area A of the side plate 44 is designed to be larger than the pressure 
receiving area B of the side plate 43, a differential force, depending on 
the difference between the areas A and B, is exerted on the side plate 44, 
which thus pressures the side plate 43 toward the right, as viewed in FIG. 
2, through the casing 40. This differential force is further exerted on 
the output shaft 31 and the friction disc 24 through the bearing 32, which 
is in abutting engagement with side plate 43, so as to thereby generate 
contact pressure between the balls 25 and the guide ways 23a and 24a of 
the discs 23 and 24. Pre-load contact pressure is generated by means of 
the spring 46 pressuring the side plate 44. Accordingly, in the situation 
where no load is acting on the pump, such pre-load contact pressure of the 
spring 46 effectively serves to transmit rotation of the input shaft 28 to 
the output shaft 31. Since the pump driving torque in this situation is 
small, even a weak contact pressure to the guide ways 23a and 24a is 
sufficient to prevent slip. When the load to the pump is increased, 
however, the pressure force of fluid against the side plate 44 is 
strengthened in proportion to the pump load, whereby power transmission 
may be performed in adaptation to the driving torque required by the pump. 
FIG. 5 is illustrative of another embodiment which is different from the 
foregoing embodiment in that a piston 81 is provided to apply on the outer 
end of the output shaft 31 a pressure force corresponding to the pump 
load, and in that a centrifugal governor is employed as a control means of 
the output/input speed ratio. Description will hereinafter be made mainly 
with the difference in construction between the embodiments. The pressure 
chamber 67 is defined between the cap member 45 closing the open end of 
the main housing 20 and the side plate 44, and a cylinder 80 opening into 
the pressure chamber 67 is formed at the outer side of the side plate 44 
in axial alignment with the pump rotor 42. The outer end of the output 
shaft 31 is extended into the cylinder 80, within which the piston 81 is 
snugly contained in abutting engagement with the outer end of the shaft 
31. Between the piston 81 and the cap member 45 there are interposed a set 
of washer springs 83 and a thrust bearing 82, the former being in a 
compressed state. Pressurized fluid delivered into the pressure chamber 67 
acts on the side surface 82a of the piston 81 receiving the washer springs 
83. Accordingly, contact force to every rotational friction surface or 
portion of the speed converter T depends upon the washer springs 83 when 
no load is acting on the pump, while it depends upon, in addition to the 
washer springs 83, a pressure of fluid pumped into the pressure chamber 67 
when load to the pump is increased. Thus, the contact force is 
automatically controlled to prevent slip at every rotational friction 
portion, whereby power transmission may be performed reliably in 
adaptation to the load of the pump. 
Further, the centrifugal governor, acting as a control means of the 
output/input speed ratio, comprises an annular V-groove 85 formed on the 
inner side surface of the friction disc 23, a guide disc 86 formed with 
another annular V-groove 87 in face-to-face relation with the groove 85 
and being capable of axially moving the forked member 54 engaging the 
rollers 26, and a plurality of balls 88 disposed between both the 
V-grooves 85 and 87. The guide disc 86 is rotatably carried on a bearing 
bushing 90, which is supported on a pilot rod 89 for axial movement 
therealong. The pilot rod 89 is secured at its one end to the retaining 
case 27 in axial alignment with the input shaft 28. A snap ring 92 is 
provided on the other end of the pilot rod 89 to prevent the bearing 
bushing 90 from falling out. A compression spring 91, having a nonlinear 
characteristic of stress, is interposed in compressed state between the 
forked member 54 and a flange portion of the pilot rod 89 so as to 
pressure the forked member 54 upon the end face of the bearing bushing 90. 
With rotation of the input shaft 28, the balls 88 are rotated together 
with the guide disc 86 and, under the action of centrifugal force, are 
moved radially of the guide disc 86 to axially displace the same. The 
guide disc 86 compresses the spring 91 and moves the forked member 54 to a 
position where it balances the force of the spring 91. Consequently, the 
support shafts 26a of the retaining rollers 26 are pivoted, which results 
in angularly tilting the rotational axes of the balls 25 to control the 
output/input speed ratio. Therefore, the rotational speed of the output 
shaft 31 can be maintained at a predetermined value regardless of any 
changes in the rotational speed of the input shaft 28, whereby pressurized 
fluid can be delivered from the pump at a predetermined flow rate. 
FIG. 6 is illustrative of an alternative embodiment of that illustrated in 
FIG. 5. An anti-friction ball 95 is provided between the outer end of the 
output shaft 31 and the piston 81, and a pre-loaded spring 96 is 
interposed between the piston 81 and the cap member 45. In this particular 
embodiment, since no relative rotation occurs between cylinder 80 and the 
piston 81, reliable sealing therebetween may be achieved. 
Referring now to FIG. 7, there is shown a further embodiment, in which 
elimination of the above-noted piston 81 allows the pump loaded pressure 
to directly act on the outer end of the output shaft 31. Between the 
output shaft 31 and the side plate 44, an O-ring seal 97 is disposed to 
prevent leakage therebetween. Further, a set of washer springs 100, 
together with a thrust bearing 99, are interposed between the cap member 
45 and a spring shoe 98, which is in abutting engagement with the outer 
end of the output shaft 31, so as to apply pre-loaded contact force on the 
output shaft 31. 
As described above, a speed converter according to the present invention is 
arranged to receive at every friction engagement portion a contact force 
which corresponds to the pressure of the fluid from the pump driven by the 
output shaft. Because of the contact force generated in adaptation to the 
driving power to be transmitted by the speed converter, not only can wear 
at the friction engagement portion be decreased, but reliable power 
transmisson can also be attained. Further, in addition to an advantage 
that optimum contact force can be generated using the sole pressuring 
means, whether the output/input speed ratio is more than 1 or less than 1, 
the speed converter can be exact and reliable in operation for a long 
life, since it is simple in construction and is freed from wear-caused 
deterioration in function. 
Obviously many modifications and variations of the present invention are 
possible in light of these teachings. It is therefore to be understood 
that within the scope of the appended claims, the present invention may be 
practiced otherwise than as specifically described herein.