JPH0327783B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuously variable traction roller transmission in which torque is transmitted via a torque transmitting power roller pivotally supported within a housing and engaged with a toroidal input/output disk.

In such a transmission, the power roller is rotatably mounted on the pivot structure so as to cause a change in the diameter of the engagement circle between the power roller and the toroidal input/output disk in accordance with a desired speed ratio. .
The power roller pivot assembly is mounted for axial movement to initiate a change in transmission ratio. This includes, for example, U.S. Patent No. 2 issued May 2, 1978 to Charles E.
This is achieved by a flexible static tension sheet such as that shown in No. 4,086,820.

However, the forces applied to the power roller and, through the power roller pivot assembly, to the tension sheet are significant and therefore require a high strength pivot assembly and appropriate pivot bearings therefor. Also, transmissions are not necessarily vibration-free, which vibrations are transmitted from the power roller to the power roller pivot assembly and its bearings, and ultimately to the transmission housing.

In order to firmly support the power roller and the power roller pivot assembly in a simple, inexpensive manner and essentially vibration-free, the power roller is arranged between and engaged with opposing toroidal input/output disks. A continuously variable power roller transmission is formed in the housing and opposite the power rollers adjacent to the walls of each partially cylindrical support cavity having a center of curvature coinciding with the pivot axis of the pivot structure. It includes a power roller pivot assembly with a pressurized fluid receiving cavity. Pressurized fluid supplied to the support cavity directly supports the power roller pivot assembly. Because it is evenly supported, the pivot structure is not subjected to bending stress,
In addition, since it floats on pressurized fluid, the pivot structure can be easily rotated even when large torque is transmitted through the transmission and a large contact force is applied to the contact area between the power roller and the toroidal disk. .

A traction roller transmission as shown in Fig. 1 has a bearing 1.
It consists of a housing 10 having coaxial input and output shafts 12 and 14 rotatably supported by 6 and 18. The input and output shafts 12 and 14 have toroidal input/output disks 20 and 2 arranged opposite each other such that a toroidal cavity 24 of circular axial cross section is defined therebetween.
2 is installed. Power rollers 26 and 28 are rotatably supported within the toroidal cavity 24.
It engages toroidal input/output disks 20 and 22.

Toroidal input/output disks 20 and 22 are mounted on the ends of shafts 12 and 14 by screws 30 and seated on flanges 32 and 34.
Axial support is provided to the input and output disks 20 and 22 by axial thrust bearing assemblies 36 and 38. Each axial thrust bearing assembly consists of a hydrostatic bearing consisting of a region within a controlled sealing ring 40 that is axially slidably disposed within an annular sealing ring cavity 42 and underpressurized fluid under static pressure. A mechanical axial thrust bearing 44 is included to provide minimal bearing support to avoid damage during start-up operations provided to the axial thrust bearing. The mechanical bearing 44 has an axially movable bearing ring 46 with a disc spring 48 disposed behind it to provide a minimum degree of engagement between the toroidal input/output disks 20 and 22 and the power rollers 26 and 28 at all times. There is a collision.

Power rollers 26 and 28 are connected to input shaft 12 and output shaft 14 by allowing rotation of the power rollers about an axis perpendicular to a plane containing the axes of the input and output shafts.
The power rollers 26 and 28 are rotated on a pivot structure 50 that allows the power rollers 26 and 28 to engage the toroidal input/output disks 20 and 22 in circles of different diameters for adjustment of various power transmission ratios between the movably supported.

For supporting the pivot structure 50, the housing 10
has a semi-cylindrical cavity 52 within which a hydrostatic trunnion support structure 54 extends. The trunnion support structure 54 has a wall 56 surrounding a trunnion support cavity 58 adapted to be pressurized with hydraulic fluid to support the pivot structure 50.
These cavity walls 56 have sealing strips 60 supported adjacent to the semi-cylindrical walls of the housing 10 defining the housing cavity 52. This sealing strip 60
Behind the sealing strip 60 and the housing cavity 52
a number of springs 62 to provide a sealing engagement with the wall of the
is installed.

The power roller 26 is connected to the roller 2 from the pivot structure 50.
6 is supported on the pivot assembly 50 by a shaft 64 projecting into a central hole 66 of the 6. power roller 26
Roller bearings 68 are provided for radial support. In operation, power roller 26 is axially supported by a hydrostatic bearing formed by bearing cavity 70 surrounded by sealing ring 72 . A support roller bearing 74 is provided to support the power roller when insufficiently pressurized fluid is supplied to the bearing cavity 70, for example during start-up. The support bearing 74 is axially movably supported by a disc spring 76 to keep the power roller 26 in engagement with the toroidal input/output disks 20 and 22 at all times.

A pivot assembly 50 is pivoted within housing 10 as best shown in FIG. At both axial ends of the pivot structure 50, the housing 10
are trunnion support members 82 and 8 axially supported by axial thrust bearings 86 and 88.
circular cavities 78 and 80 for rotatably receiving 4;
, the axes of the cavities 78 and 80 being essentially tangent to the center circle of the toroidal cavity defined by the toroidal input/output disk and coterminous with the centerline of curvature of the semi-cylindrical housing cavity 52. Become old and healthy.

Trunnion support members 82 and 84 project toward each other and include an integral control piston 90 arranged along an axis essentially passing through the center of the circle of contact between the surface of power roller 26 and toroidal input/output disks 20 and 22. and 92. Power roller pivot assembly 50 is formed with cylindrical cavities 96 and 98 that receive control pistons 90 and 92, respectively. Pressurized fluid is applied to cylinders 96 and 98 to axially move power roller pivot assembly 50 and thereby move power roller 26 relative to the toroidal input/output disk to initiate a change in transmission ratio. Means 100, 102 are provided for supplying.

As shown in FIG. 2, the sealing ring 72 is provided through holes 108 that provide communication between the sealing ring cavity 106 and the cylinder 96 and through holes 110 that provide communication between the sealing ring cavity 106 and the cylinder 98 on each side of the power roller 26. The power roller 26 is brought into engagement with the power roller 26 by pressurized fluid supplied to the seal ring cavity 106. Cylinders 96,9 are exposed to higher pressure control fluid within holes 108 and 110.
Sealing ring cavity 10 by pressurized fluid from pressurization of 8
Check valves 112 and 114 are respectively disposed to ensure pressurization of 6.

A pressurized lubricant passageway 104 for supplying pressurized lubricant to the trunnion support cavity 58 connects the control piston 90 and It extends through the center of pivot assembly 50 to trunnion support cavity 58 . Passage 104
To avoid leakage of pressurized lubricant from the cylinder 96 to the cylinder 96, the passageway 104 includes a tube 116 that extends into the piston 90 and is slidably sealed therein by a sealing ring 118.

The shaft 64 of the power roller 26 has an axial passage 120 for supplying pressurized lubricant to the roller bore 66 and the bearing 68. The power roller support cavity 70 is located inside the sealing ring 72 in order to force the power roller 26 into direct and firm engagement with the toroidal input/output disks 20 and 22 by the pressure of the lubricant supplied to the trunnion support cavity 58. passageway 122 for supplying pressurized fluid to
passes through the pivot structure 50.

As the input shaft 12 rotates in one direction, the output shaft 14 rotates in the opposite direction at a relative speed that depends on the pivot position of the power roller pivot assembly 50. Because of the positive engagement of the power rollers 26 and 28 with the toroidal input/output disks 20 and 22, the trunnion support cavities 58 behind the power rollers 26 and 28 subject the power roller pivot assembly 50 to essentially no bending loads. It is pressurized to prevent it from being applied.

To change the gear ratio, the power roller moves into a large contact circle with one of the toroidal input/output disks 20 and 22 and into a small contact circle with the other to rotate the power roller pivot structure 50. It is started by changing the gear ratio. Axial movement and rotation of the power roller pivot assembly 50 is facilitated because the power roller and its pivot assembly 50 are floatingly supported by the lubricant within the trunnion support cavity 58. Axial movement of the pivot assembly 50 is achieved by supplying pressurized fluid to one of the cylinders 96, 98 and discharging pressurized fluid from the other.

Lubricating and support fluid is passed through passageway 104 at a pressure sufficient to absorb the forces necessary to support power roller 26 and pivot assembly 50 and hold them in engagement with toroidal input/output disks 20, 22. is supplied to the trunnion support cavity 58. The force required to hold the power roller in engagement with the toroidal input/output disk depends on the torque to be transmitted, and thus the fluid pressure providing the contact force is controlled in dependence on the torque to be transmitted. .

The transmitted torque is transmitted through power rollers 26, 28 and creates an axial trunnion force that must be balanced by differential control fluid pressure within control cylinders 96 and 98. The pressure difference in the control cylinders 96 and 98 is therefore a measure of the torque transmitted, and it is also the force required to engage the power rollers 26, 28 and the toroidal input/output discs 20, 22 to avoid slippage. is a direct measure of

so that the low pressure level remains essentially constant.
Alternatively, if the gear ratio is controlled to be constant to a certain extent depending on the pivot position of the trunnion, for example, if the gear ratio control arrangement is used as described in JP-A-58-54262, high pressure will be transmitted. Self-adjusts according to torque. The high pressure in that case is a measure of the force required to engage the power roller and the toroidal disc. This higher control fluid pressure depends on the direction in which the torque is transmitted, i.e. the direction of rotation in which the torque is transmitted.
This can occur in either cylinder 96 or 98. In any event, with the arrangement described above, the higher control fluid pressure is applied to the bore 108 or the bore while the check valve 114 or 112 is closed to maintain the higher control fluid pressure within the sealing ring cavity 106. Sealing ring cavity 1 through 110
Added to 06. Accordingly, the sealing ring 72 increases as the transmitted torque increases and reduces leakage through the controlled sealing ring 72 from the power roller support cavity 70 into the trunnion support cavity 58 and into the power roller support cavity 70. The power roller 26 is forced toward the power roller 26 with a force that causes an accumulation of pressure within the power roller 26 .

A control arrangement for supplying control fluid to cylinders 96 and 98 is shown schematically in FIG. The trunnion support member 82 has a control shaft 124 connected to rotate integrally with the power roller pivot assembly 50 and move in the axial direction together with the pivot assembly 50. At its free end, the shaft 124 carries a cam assembly 126, which cam replacement 124, at its face 128, supplies fluid to and from the cylinders 96 and 98, as detailed in the aforementioned JP 58-54262. 4 designed to control the discharge of fluid of
It has a precess cam 130 abutted by a control stem 132 of a directional control valve 134. However, the minimum power roller engagement force depends on the minimum control fluid pressure. The desired minimum force also depends on the pivot position of the power roller. The minimum pressure is therefore controlled by a pivot position sensing control valve 136 located in a pressure relief line 138 from control valve 134 and actuated by a circumferential cam 140 on cam assembly 126.

The pivot position sensitive control valve 136 may comprise a cylinder 142 having a piston 144 movably disposed therein, the piston 144 having a spring 146 abutting a cam follower actuated by a cam 140.
energized by. Piston 144 allows control fluid to be discharged into discharge line 150 only when the control fluid pressure is sufficient to open control valve 136 against the force of spring 146 which depends on the pivot position of power roller 26. Preferably, the discharge line 150 is provided with a restriction 152 to avoid rapid pressure changes that could lead to cavitation. A bypass 15 is also preferably provided between the lubricant supply line 156 from the pump 158 and the exhaust line 138 to establish a minimum pressure within the exhaust line 138.
4 is provided, the bypass 154 including an orifice 160 that allows only a relatively small flow, substantially less than that possible through the restriction 152.

Pressurized fluid is supplied to a semi-cylindrical trunnion support cavity 58 via a supply conduit 162 with a flow restriction orifice 164 which is connected to the fluid supply and sealing ring 72 of the power roller 26.
The pivot assembly and power roller support pressures can be controlled depending on the transmitted torque, adjusted by the leakage allowed by the torque.

With this device, precise speed control can be achieved and unnecessary loading of the traction surface is also avoided. Pressurized lubricant is supplied to all hydrostatic bearings by a single pump. However, the supply lines to the various bearings preferably include orifices to ensure proper distribution of pressurized lubricant to the various hydrostatic bearings.

However, the invention is not limited to the apparatus described above and shown in the drawings. For example, a single trunnion assembly could be provided with a control piston arranged in the pivot of the trunnion. Although such a device is simpler than the illustrated device, slight bending forces are generated which can cause precessing movement of the trunnion. However, in relatively low torque transmissions, it is quite easy to accommodate such forces.

It should be noted that in a device such as that shown in FIG. 2, axial thrust bearings 86 and 88 for trunnion support members 82 and 84
is that the axes of cylinders 96 and 98 are preferably large enough to pass through the space surrounded by bearings 86 and 88 to provide proper loading of the axial thrust bearings 86 and 88.

Additionally, a trunnion support cavity 58 is formed between the power roller pivot structure 50 and the housing 10.
may be circular with a curved sealing ring 60 abutting the semi-cylindrical wall of the housing 10;
Alternatively, the straight first sealing strip can be attached to the pivot structure 50.
The second sealing strip portion may be rectangular in cross-section with a partially circular second strip portion aligned in the direction of the axis of the sealing strip portion and perpendicular to the first sealing strip portion. Finally, the trunnion support cavity 58 may be separated by a separation wall 166 and the sealing strip 168 may be arranged within the separation wall 166.

[Brief explanation of drawings]

Fig. 1 is an axial sectional view of the traction roller transmission, Fig. 2 is a sectional view taken along the - line in Fig. 1, and Fig. 3 is a control system for controlling pressurized fluid supply to the traction roller transmission. FIG. [Description of symbols of main parts], 10... Housing, 12... Input shaft, 14... Output shaft, 20, 2
2... Toroidal input/output disk, 24... Toroidal cavity, 26, 28... Power roller,
36, 38...Axial thrust bearing structure, 50...
...Power roller pivot support structure, 58...Trunion support cavity, 70...Power roller support cavity, 72...
... Sealing ring, 82, 84 ... Trunnion support member, 86, 88 ... Axial thrust bearing, 90,
92... Control piston, 96, 98... Cylinder, 100, 102... Pressurized fluid supply means, 10
4... Passage, 112, 114... Check valve, 120
... Axial passage, 122 ... Passage, 126 ... Cam structure, 134 ... Four-way control valve, 136 ... Pivot position sensing control valve, 142 ... Cylinder, 1
44... Piston.

Claims (1)

[Scope of Claims] 1. A housing, coaxial input and output shafts rotatably supported within the housing, facing each other, one supported by the input shaft and the other by the output shaft, with a circular cross section between them. 2 having opposed toroidal surfaces defining a toroidal cavity of
at least two torque transmitting power rollers disposed between the toroidal discs and each engaging the toroidal input/output disc for transmitting torque therebetween; a pivot assembly pivotally mounted within the housing to rotatably support the input and output toroidal disks and permit variation of the torque transmission ratio between the input and output toroidal disks; each having a partially cylindrical wall forming a cavity adjacent thereto, the center of curvature of the partially cylindrical wall substantially coinciding with the pivot axis of said pivot structure, said pivot structure being a cylindrical member of said housing. a trunnion support cavity formed adjacent to the cylindrical wall portion, and further for supplying pressurized fluid to the trunnion support cavity to provide support for the pivot structure on the cylindrical wall portion. A traction roller continuously variable transmission comprising means. 2. In claim 1, the pivot structure defines the support cavity and is shaped to abut an adjacent housing wall and is spring biased into engagement with the housing wall. Traction roller continuously variable transmission with walls carrying sealing strips. 3. In claim 1, the pivot structure has an axial piston and cylinder structure arranged at both ends thereof, and the pivot structure is moved in the axial direction to initiate a change in the gear ratio. means for selectively supplying pressurized fluid to said piston and cylinder assembly. 4. According to claim 3, a trunnion support member is disposed within the housing adjacent an axial end of the pivot assembly and has a pivot axis substantially tangential to a central circle of the toroidal cavity. The piston and cylinder assembly is rotatably supported about the power roller and the toroidal input/output disk in such a manner as to minimize the reaction forces that generate precess motion on the pivot assembly when torque is transmitted. A traction roller transmission having a centerline passing through a plane defined by a circle. 5. In claim 4, an axial thrust bearing is arranged between the trunnion support member and the housing, and the axial thrust bearing is arranged between the transmission pivot and the centerline of the piston and cylinder structure. Traction roller transmission with a radius exceeding a distance of . 6. In claim 5, the trunnion support member includes the piston extending into a cylinder formed in the pivot structure such that the pivot structure is axially movably supported by the piston. , a traction roller transmission in which the pressurized fluid supply means includes a passageway through the trunnion support member. 7. The traction roller transmission of claim 1, wherein each power roller includes a hydrostatic power roller support cavity defining a hydrostatic cavity communicating with the trunnion support cavity and receiving pressurized fluid therefrom. 8. In claim 6, each power roller includes a hydrostatic power roller support cavity having a hydrostatic bearing sealing ring axially movably disposed within an annular sealing ring cavity, said annular sealing ring cavity including said annular sealing ring cavity. A traction roller transmission in communication with at least one of the cylinders of the piston and cylinder arrangement. 9. According to claim 8, a communication passage is provided between the sealing ring cavity and a cylinder formed in the power roller pivot structure, and in the communication passage there is provided a communication passage from the cylinder carrying a higher pressure fluid. A check valve is arranged to supply pressurized fluid to the seal ring cavity to control fluid pressure within the trunnion support cavity and the hydrostatic power roller support cavity in response to the pressure of the higher pressure fluid. Has a traction roller transmission. 10. The traction roller transmission of claim 1, wherein the trunnion support cavity is segmented to provide multiple support cavity chambers. 11. According to claim 1, a source of pressurized fluid is provided to cause selective supply of control fluid to the cylinder to rotate the power roller pivot assembly to a desired ratio pivot position. a traction roller transmission, wherein a control valve is associated with at least one of said pivot structures, and means are provided for controlling the pressure of fluid discharged from said cylinder in response to a pivot position of said transmission. . 12. As defined in claim 11, said means for controlling the discharge pressure of said control fluid is adapted to apply a spring force of a spring-loaded control valve associated with said pivot structure to a pivot point of said pivot structure. A traction roller transmission which is a spring-loaded pressure control valve having a biasing means adapted to be position dependent. 13. The traction roller transmission according to claim 12, wherein the biasing means is a cam follower that abuts against a cam structure that is rotatably mounted to the pivot structure.