JP2003035351A - Single cavity type toroidal-type continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently and highly maintain transmission efficiency as a transmission without generating a more excessive pressing load than a required design load to an input disk and an output disk even if a shifting ratio is changed and by reducing dynamic torque loss during operation. SOLUTION: A hydraulic loading mechanism 22 is provided on the rear face 4a side of the input disk 4. A cylinder 24 of the hydraulic loading mechanism is a member provided with a tube part 26, a disk part 28, and an annular edge part 30. The annular edge part is fitted to an outer circumference from the rear face 4a side of the input disk 4 and a space surrounded by the rear face 3a of the annular edge part and a bottom face 28a of the disk part 28 opposing to the rear face 4a is made as a cylinder chamber 32. Pressurized oil of which the pressure is boosted by a pump P is supplied to the cylinder chamber 32 through a pressurized oil conduit 40, oil passages 38a, 18b, 38c, and 38d.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-cavity toroidal type continuously variable transmission used as, for example, a transmission of an automobile.

[0002]

2. Description of the Related Art A toroidal type continuously variable transmission, which is mainly used as a transmission for an automobile, has an input disk and an output disk each of which has a concave cross-section whose surfaces facing each other are sandwiched between these disks. It has a toroidal speed change mechanism that is combined with a rotatable power roller. The input disc is drivingly coupled to the torque input shaft so as to be movable in the direction of the torque input shaft, and the output disc is rotatable relative to the torque input shaft and is movable in a direction away from the input disc. Is mounted opposite the input disc so that it is limited.

In the toroidal type speed change mechanism as described above,
When the input disc rotates, the output disc reversely rotates via the power roller, so the rotational motion input to the torque input shaft is transmitted to the output disc as a rotational motion in the opposite direction and rotates integrally with the output disc. Taken out from the output gear. At this time, the torque input shaft is accelerated to the output gear by changing the inclination angle of the rotation shaft of the power roller so that the peripheral surface of the power roller contacts the outer periphery of the input disc and the center of the output disc, respectively. On the contrary, the torque input shaft is rotated by changing the inclination angle of the rotation shaft of the power roller so that the peripheral surface of the power roller contacts the vicinity of the center of the input disc and the vicinity of the outer periphery of the output disc, respectively. To the output gear. Further, a gear ratio between the two can be obtained almost steplessly by appropriately adjusting the inclination angle of the rotating shaft of the power roller.

In order to adjust the frictional forces generated between the input disc and the power roller and between the power roller and the output disc to always have appropriate magnitudes, the torque input shaft is fixed to the end of the input disc side. A loading cam mechanism that can increase or decrease the pressing force in the input shaft direction according to the input torque is arranged between the loading nut and the input disk. The loading cam mechanism has a cam surface having an uneven shape extending in the circumferential direction.The cam disk is engaged with the torque input shaft and rotates integrally with the torque input shaft. An input disk provided on the surface facing the cam surface of the disk and rotating relatively to the torque input shaft, a substantially circular ring-shaped cage sandwiched between these, and a cage in the circumferential direction of the cage. It is composed of rolling elements which are respectively arranged in openings provided at a plurality of locations. Further, each rolling element is held in the opening of the retainer so as to be rotatable about the radial direction of the retainer as a central axis, and the side surface of each rolling element has unevenness on both cam surfaces of the cam disc and the input disc. Is installed so as to abut.

The torque input shaft is rotatable with respect to the casing of the toroidal type continuously variable transmission by a bearing provided at an end portion on the input disk side and an input side bearing provided at an end portion on the output disk side. Supported by. Separately from this, the output gear is also rotatably supported by a casing of the toroidal type continuously variable transmission by an output side bearing provided on the rear surface of the output gear. The output side bearing and the input side bearing are held back-to-back by support members connected to the casing of the toroidal type continuously variable transmission.For example, when an angular bearing is used, the contact angle directions are opposite to each other. To be combined.

When the torque input to the torque input shaft is transmitted to the output gear, the torque input shaft is attracted toward the input disc by the action of the loading cam mechanism, and the output gear is moved toward the output disc. Pushed out. Therefore, a thrust load in the input disk direction is applied to the input side bearing, and a thrust load in the output disk direction is applied to the output side bearing.

[0007]

In a single-cavity toroidal type continuously variable transmission including only one toroidal type transmission mechanism as described above, the pressing load generated by the loading cam mechanism is proportional to the input torque. Depending on the gear ratio, a pressing load larger than the required design load is generated on the input disk and the output disk.
Therefore, the thrust load applied to the output side bearing and the input side bearing becomes large, the rotational resistance to the bearing portion remarkably increases when transmitting high torque, etc., and the durability of the output side bearing and the input side bearing deteriorates. There is a risk.

Further, it is inevitable that the dynamic torque loss during operation becomes extremely large, and the transmission efficiency of the transmission cannot be maintained sufficiently high.

The present invention has been made in view of the above circumstances, and even if the gear ratio changes, a pressing load that is larger than the required design load is not generated on the input disk and the output disk, and when the operation is performed, An object of the present invention is to provide a single-cavity toroidal type continuously variable transmission that can reduce dynamic torque loss and maintain transmission efficiency as a transmission sufficiently high. Further, according to the present invention, even if the gear ratio changes, a pressing load that is larger than the required design load does not occur on the input disc and the output disc, and dynamic torque loss during operation is reduced to reduce transmission efficiency as a transmission. It is an object of the present invention to provide a single-cavity toroidal type continuously variable transmission that can maintain a sufficiently high value and does not reduce the durability of the output side bearing and the input side bearing.

[0010]

To achieve the above object, a single-cavity toroidal type continuously variable transmission according to a first aspect of the present invention is provided with an input disk drive-coupled to an input shaft and the input shaft. An output disc that is mounted to face the input disc so as to be relatively rotatable with respect to the input disc so as to limit movement in a direction away from the input disc; and the input disc and the output that each have an arcuate concave cross section. A set of toroidal type speed change mechanism composed of a rotatable power roller sandwiched between the discs so as to come into contact with mutually facing surfaces of the discs; an output gear rotating integrally with the output disc;
An output side bearing provided behind the output gear for supporting a thrust load applied from the output disc, and an input side bearing provided at an end of the torque input shaft on the output disc side for supporting a thrust load applied from the input disc. And a single-cavity toroidal-type continuously variable transmission including a pressing mechanism that presses at least one of the input disk and the output disk in a direction in which the input disk and the output disk are brought close to each other,
The pressing mechanism includes a hydraulic drive source, a cylinder connected to the hydraulic drive source, and a piston housed in the cylinder to form a cylinder chamber, and pressurizing oil generated in the hydraulic drive source is supplied to the cylinder. It is a device adapted to press at least one of the input disc and the output disc by supplying the chamber.

According to a second aspect of the present invention, in the single-cavity toroidal type continuously variable transmission according to the first aspect, the pressing mechanism includes a control device for controlling the drive of the hydraulic drive source. The device controls the drive of the hydraulic drive source so that the pressure value of the pressurized oil increases when the temperature of the oil supplied to the cylinder chamber exceeds a predetermined value.

According to a third aspect of the present invention, in the single-cavity toroidal type continuously variable transmission according to the first or second aspect, the reaction force applied to the outer rings of the output side bearing and the input side bearing is opposite to the opposite direction. And a hydraulic actuator that reduces the thrust load input to the output side bearing and the input side bearing.

Further, the invention of claim 4 is the same as that of claim 3.
In the single-cavity toroidal type continuously variable transmission described, a hydraulic drive source that supplies hydraulic pressure to the pressing mechanism,
The hydraulic drive source that supplies hydraulic pressure to the hydraulic actuator is the same hydraulic drive source.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a first embodiment of a single-cavity toroidal type continuously variable transmission according to the present invention.

The single-cavity toroidal type continuously variable transmission according to the present embodiment is configured so that the input shaft 2 as a torque input shaft rotatably driven by a drive source E including an engine and the like can be moved in the axial direction. One input disc 4 drivingly coupled to the input shaft 2 is mounted so as to be rotatable relative to the input shaft 2 and to be opposed to the input disc 4 so that movement in a direction away from the input disc 4 is restricted. And a pair of toroidal speed change mechanisms 10 each having an output disc 6 and a rotatable power roller 8 held between arcuate concave surfaces of the input disc 4 and the output disc 6 facing each other. ing.

The input shaft 2 includes a bearing 12 located at the end of the input disk 4 side opposite to the drive source E and an input side angular bearing 14 located on the output disk 6 side.
It is rotatably supported by the casing of the toroidal continuously variable transmission. The output gear 16 is also disposed between the rear surface of the output disk 6 and the output side angular bearing 18 and is rotatably supported. The input side angular bearing 14 and the output side angular bearing 18 are arranged so as to be back-to-back.

A hydraulic loading mechanism 22 is provided between the input nut 4 and the loading nut 20 fixed to the end of the input shaft 2 on the input disc 4 side. The hydraulic loading mechanism 22 includes a cylinder 24. The cylinder 24 includes a cylindrical portion 26 coaxially arranged on the outer periphery of the input shaft 2 and a disc portion 2 integrally formed on the outer periphery of the cylindrical portion 26.
8 and an annular edge portion 30 that extends from the outer circumference of the disk portion 28 in the axial direction of the input shaft 2, and a part of the inner peripheral side and the outer peripheral side of the tubular portion 26 is the outer circumference of the input shaft 2. The cylinder 24 is slidably provided along the axis of the input shaft 2 by being spline-engaged with the inner circumference of the input disk 4.

The cylinder 24 has an annular edge 30 fitted to the outer periphery from the rear surface 4a side of the input disk 4, and the rear surface 4a and the bottom surface 28 of the disk portion 28 facing the rear surface 4a.
The space surrounded by a is a cylinder chamber 32. The cylinder chamber 32 is kept liquid-tight by seal members 34 and 36. In the cylinder portion 26 and the input shaft 2, a plurality of oil passages 38 a, 38 b, 38 c, 3 are provided toward the cylinder chamber 32.
8d is formed, and the pressurized oil supplied through the pressurized oil introducing pipe 40 is supplied to the oil passages 38a, 38b, 38c, 38d.
And is supplied to the cylinder chamber 32. Pressurized oil introduction pipe 4
Pressurized oil passing through 0 is boosted by the pump P. Pump P
Is controlled by an ECU (Engine Control Unit) 1, and the ECU 1 sets an appropriate pressure value of the pressurized oil from the input torque, the gear ratio, the rotation speed, the frequency, the temperature of the pressurized oil, and the like. Pump P to make pressurized oil of a predetermined pressure value
Drive control. The back surface 4a of the input disk 4 is
It corresponds to the piston of the present invention.

According to the above structure, the pressurized oil generated by the pump P is supplied to the pressurized introduction pipe 40, the oil passages 38a, 38b, 38c,
When supplied into the cylinder chamber 32 of the hydraulic loading mechanism 22 via 38d, the supplied pressurized oil moves in a direction in which the bottom surface 28a of the disk portion 28 of the cylinder 24 and the back surface 4a of the input disk 4 are separated from each other. The input disk 4 moves and is pressed against the output disk 6. As described above, the hydraulic loading mechanism 22 presses the input disk 4 toward the output disk 6 when the pressurized oil is supplied to the cylinder chamber 32.

In this state, the inclination angle of the rotating shaft of the power roller 8 is changed so that the peripheral surface of the power roller 8 contacts the outer periphery of the input disc 4 and the center of the output disc 6, respectively. The speed is increased from 2 to the output gear 16, and conversely, the peripheral surface of the power roller 8 of the power roller 8 is brought into contact with the vicinity of the center of the input disk 4 and the vicinity of the outer circumference of the output disk 6, respectively. By changing the inclination angle of the rotating shaft, deceleration from the input shaft 16 to the output gear is performed. As described above, the hydraulic loading mechanism 22 presses the input disk 4 toward the output disk 6, whereby the rotational driving force transmitted from the drive source E is input to the input disk 4, the power roller 8, the output disk 6, and the output gear. It is transmitted to the output side via 16.

4 to 6 show transmissions of a single cavity type toroidal type continuously variable transmission having a conventional loading cam mechanism and a single cavity type toroidal type continuously variable transmission having a hydraulic loading mechanism of the present embodiment. The calculation result which simulated the efficiency is shown. The broken line connecting the black diamonds is the transmission efficiency of a single-cavity toroidal continuously variable transmission equipped with a loading cam mechanism, and the solid line connecting the black diamonds is the single-cavity toroidal equipped with a hydraulic loading mechanism. It is the transmission efficiency of the type continuously variable transmission. In the calculation, the cavity diameter is 124 mm,
The design traction coefficient in the case of the loading cam mechanism was set to 0.052 and the design traction coefficient in the case of the hydraulic loading mechanism was set to 0.057. Under these conditions, the efficiency calculation of the traction part and the loss torque of the bearing were calculated. .

From the results of FIGS. 4 to 6, it can be understood that the transmission efficiency of the single cavity type toroidal type continuously variable transmission equipped with the hydraulic loading mechanism is improved by 5% at the maximum. Moreover, since the reaction force of the input disk 4 and the output disk 6 can be reduced by adopting the hydraulic loading mechanism, the durability is improved. Further, if the same level of durability is sufficient, the bearing can be downsized, the bearing loss torque can be reduced, and further improvement in efficiency can be expected.

As described above, according to the single-cavity toroidal type continuously variable transmission of this embodiment, the input torque,
Based on the gear ratio, rotation speed, vibration frequency, and temperature of the pressurized oil, E
The CU 1 performs the optimum hydraulic pressure adjustment of the hydraulic loading mechanism 22, and the input disk 4 presses the output disk 6 with the optimum pressing force. Therefore, even if the gear ratio changes, the pressing load that is larger than the required design load is not generated in the input disk 4 and the output disk 6, and the output side angular bearing 18
Also, the durability of the input side angular bearing 14 does not decrease.

Further, it is possible to provide a single-cavity toroidal type continuously variable transmission that can reduce the dynamic torque loss during operation and maintain the transmission efficiency of the transmission sufficiently high.

By the way, when the temperature of the pressurized oil becomes high, the limit traction coefficient is lowered, so that the safety factor of design is lowered and the margin is reduced. Therefore, in this embodiment,
When the oil temperature exceeds 100 ° C., the ECU that receives the temperature information inputs the pump P to increase the pressure of the pressurized oil.
Is controlled to set the traction coefficient to 0.052. As a result, the margin is increased by about 10% as compared with the traction coefficient of 0.057 when the temperature is 100 ° C. or less, and the reliability against gloss slip is improved.

Next, FIG. 2 is a sectional view showing a second embodiment of the single-cavity toroidal type continuously variable transmission according to the present invention. The same components as those shown in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the present embodiment, the output side angular bearing 18
And a hydraulic actuator 5 for exerting an outward hydraulic pressure on the outer rings 18a, 14a of the input side angular bearing 14.
0 is arranged adjacent to the output side angular bearing 18 and the input side angular bearing 14.

A support member 52, which is a constituent member of the hydraulic actuator 50, is provided between the output side angular bearing 18 and the input side angular bearing 14 and extends in the circumferential direction on the inner wall surface of the casing 54 of the toroidal type continuously variable transmission. It is fitted in a circular groove formed along the. Two cylinders 56 and 58, which are coaxial with the input shaft 2 and face each other, are arranged on the inner peripheral portions of both end surfaces of the support member 52. One disk-shaped piston 60, 62 is fitted in each cylinder 56, 58, and each piston surface of these pistons 60, 62 has an outer ring 18a of the output side angular bearing 18 and the input side angular bearing 14 respectively. , 14a.

The cylinders 56, 58 and the pistons 60, 62 constitute the hydraulic pressure actuator 50, and the oil introduced from the hydraulic circuit on the high pressure side (not shown) whose pressure rises according to the traction force is transferred to the casing. It is introduced from a supply hole (not shown) provided in 54 through a common oil passage 64 provided in the support member 52, and each cylinder 5
The oil is supplied into the cylinders 56, 58 through oil holes 66, 68 formed on the bottom surfaces of the cylinders 6, 58.

The output side angular bearing 18 is the output gear 16
And integrally rotates with the output disk 6 and the output gear 16. In this embodiment, a circular ring-shaped recess is provided on the back surface of the output gear 16, and the outer ring 18a of the output side angular bearing 18 is fitted into this recess so that the output side angular bearing 18 has the output gear 16. Since the structure is such that it sunk into the inner diameter portion, the rotational rigidity of the coupling portion between the output gear 16 and the output side angular bearing 18 can be increased. Further, the axial dimension of the input shaft 2 is shortened as compared with the usual serial arrangement, which contributes to downsizing of the toroidal type continuously variable transmission as a whole. On the other hand, the input side angular bearing 1
4 is integrated with the input shaft 2 via a flange member 69, and integrally rotates with the torque input shaft 2 and the flange member 69.

According to the above configuration, the hydraulic actuator 5
0 moves the pistons 60 and 62 in the axial direction of the input shaft 2 according to the pressure of the oil (hydraulic pressure) supplied into the cylinders 56 and 58, so that each of the output side angular bearing 18 and the input side angular bearing 14 The outer rings 18a and 14a are pressed to reduce the thrust load applied to the outer rings 18a and 14a. Therefore, each angular bearing 18, 1
The outer ring 18a, 14a of No. 4 actually receives the force obtained by subtracting the hydraulic pressure of the pistons 60, 62 from the reaction force of the input / output discs 4, 6, so that the angular bearings 18, 1
The thrust load that the No. 4 ball receives from the outer rings 18a, 14a and transmits to the inner ring is significantly reduced. Both outer rings 18a, 14
Since the thrust loads received by a are in the opposite directions and partially cancel each other, the difference between them is transmitted to the casing 54 of the toroidal continuously variable transmission through the support member 52.

FIGS. 4 to 6 show the transmission efficiency of the single-cavity toroidal type continuously variable transmission equipped with the hydraulic loading mechanism and the hydraulic actuator of this embodiment by the solid line connecting the black triangles. It can be understood that the transmission efficiency is improved by about 3% at the maximum as compared with the single cavity type toroidal type continuously variable transmission equipped with the hydraulic loading mechanism (the solid line connecting the black diamond marks).

Therefore, by providing the hydraulic actuator 50 in addition to the hydraulic loading mechanism 22, the thrust load applied to the output side angular bearing 18 and the input side angular bearing 14 is reduced, and each bearing 18 is transmitted when high torque is transmitted. , 14, the durability of the output side angular bearing 18 and the input side angular bearing 14 can be improved. Further, since the load applied to the output side angular bearing 18 and the input side angular bearing 14 is reduced, it is possible to reduce the size and weight of the bearing and bearing peripheral members.

Further, FIG. 3 is a sectional view showing a third embodiment of the single-cavity toroidal type continuously variable transmission according to the present invention. In the present embodiment, a pump that supplies hydraulic pressure to the hydraulic loading mechanism 22 and a pump that supplies hydraulic pressure to the hydraulic actuator 50 are made common, that is, hydraulic pressure is supplied by one pump P, and drive control of this pump P is performed. It is performed by ECU (Engine Control Unit) 2. The ECU 2 sets an appropriate pressure value of the pressurized oil based on the input torque, the gear ratio, the number of revolutions, the frequency, the temperature of the pressurized oil, etc., and the pump P is set so that the pressurized oil has a predetermined pressure value.
Drive control. That is, the ECU 2 optimizes according to the gear ratio so that the optimum pressing force is generated from the input disk 4 to the output disk 6 and the thrust load applied to the output side angular bearing 18 and the input side angular bearing 14 is reduced. The pump P is drive-controlled so that various hydraulic pressures are generated.

According to the present embodiment, by making the hydraulic pressure generation source (pump P) of the hydraulic loading mechanism 22 and the hydraulic actuator 50 common, the effects of the first and second embodiments can be obtained. It is possible to provide a single-cavity toroidal type continuously variable transmission in which the number of valves and pipes is reduced and the size is suppressed with a simple structure.

[0035]

As described above, according to the single cavity type toroidal type continuously variable transmission of the first aspect,
The pressing mechanism includes a hydraulic drive source, a cylinder connected to the hydraulic drive source, and a piston housed in the cylinder to form a cylinder chamber, and the pressurized oil generated by the hydraulic drive source is supplied to the cylinder chamber. Since at least one of the input disc and the output disc is pressed by doing so, even if the gear ratio changes, a pressing load that is larger than the required design load does not occur on the input disc and the output disc. The efficiency can be increased.

According to the single-cavity toroidal type continuously variable transmission of the second aspect, the pressing mechanism is provided with a control device for controlling the drive of the hydraulic drive source, and is supplied to the cylinder chamber by this control device. Since the drive control of the hydraulic drive source is performed so that the pressure value of the pressurized oil becomes high when the temperature of the oil exceeds a predetermined value, a more optimal pressing load is applied to the input disk and the output disk. be able to.

According to the single-cavity toroidal type continuously variable transmission of the third aspect, the reaction force applied to the outer rings of the output side bearing and the input side bearing is opposite to the hydraulic force applied to the outer ring to act on the output side bearing. Also, since the hydraulic actuator for reducing the thrust load input to the input side bearing is provided, the rotational resistance for each bearing decreases when transmitting high torque, so the durability of the output side bearing and the input side bearing is improved. be able to.

Further, according to the single-cavity toroidal type continuously variable transmission of the fourth aspect, the hydraulic drive source for supplying the hydraulic pressure to the pressing mechanism and the hydraulic drive source for supplying the hydraulic pressure to the hydraulic actuator are the same hydraulic pressure. By using the drive source, it is possible to provide a continuously variable transmission in which the number of valves and pipes is reduced and the size is suppressed with a simple structure.

[Brief description of drawings]

FIG. 1 is a sectional view showing a single-cavity toroidal type continuously variable transmission according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a single cavity type toroidal type continuously variable transmission according to a second embodiment of the present invention.

FIG. 3 is a sectional view showing a single-cavity toroidal type continuously variable transmission according to a third embodiment of the present invention.

FIG. 4 is a graph showing a simulation result comparing transmission efficiencies of a conventional device and a device of the present invention in a first speed change state.

FIG. 5 is a graph showing a simulation result comparing transmission efficiencies of a conventional device and a device of the present invention in a second speed change state.

FIG. 6 is a graph showing a simulation result comparing transmission efficiencies of a conventional device and a device of the present invention in a third speed change state.

[Explanation of symbols]

2 input axes 4 input disks 4a Rear of input disc (piston) 6 Output disc 8 power rollers 10 Speed change mechanism (toroidal type speed change mechanism) 14 Input side angular bearing (input side bearing) 16 output gears 18 Output side angular bearing (output side bearing) 22 Hydraulic loading mechanism (pressing mechanism) 24 cylinders 32 cylinder chamber 50 hydraulic actuator ECU1, ECU2 control device P pump (hydraulic drive source)

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 3J051 AA03 AA08 BA03 BD02 BE09                       CA05 CB07 DA09 EA08 EC02                       FA02                 3J552 MA09 NA01 NB01 PA59 PA61                       QB01 RA00 SA46 SA49 SA51                       VA27W VA34Z VA48W VA52W                       VA74Z

Claims (4)

[Claims] 1. An input disk drivingly coupled to the input shaft, and facing the input disk such that the input disk is rotatable relative to the input shaft and its movement in a direction away from the input disk is restricted. 1 and a rotatable power roller that is sandwiched between the input disk and the output disk, each of which has an arcuate concave cross section, so as to abut against the surfaces of the input disk and the output disk that face each other. A pair of toroidal transmissions, an output gear that rotates integrally with the output disc,
An output side bearing provided behind the output gear for supporting a thrust load applied from the output disc, and an input side bearing provided at an end of the torque input shaft on the output disc side for supporting a thrust load applied from the input disc. And a single-cavity toroidal continuously variable transmission including a pressing mechanism that presses at least one of the input disk and the output disk in a direction in which the input disk and the output disk are brought closer to each other, the pressing mechanism is A hydraulic drive source, a cylinder connected to the hydraulic drive source, and a piston housed in the cylinder to form a cylinder chamber, and the pressurized oil generated by the hydraulic drive source is supplied to the cylinder chamber. So that at least one of the input disc and the output disc is pressed. A single-cavity toroidal type continuously variable transmission characterized in that 2. The pressing mechanism includes a control device that controls the drive of the hydraulic drive source, and the control device is configured to apply pressurized oil when the temperature of the oil supplied to the cylinder chamber exceeds a predetermined value. 2. The single-cavity toroidal type continuously variable transmission according to claim 1, wherein the drive control of the hydraulic drive source is performed such that the pressure value of the hydraulic pressure source becomes high. 3. A hydraulic actuator for reducing a thrust load applied to the output side bearing and the input side bearing by causing an oil pressure in a direction opposite to a reaction force received by each outer ring of the output side bearing and the input side bearing to act. The single-cavity toroidal type continuously variable transmission according to claim 1 or 2, further comprising: 4. The single hydraulic drive source according to claim 3, wherein a hydraulic drive source for supplying hydraulic pressure to the pressing mechanism and a hydraulic drive source for supplying hydraulic pressure to the hydraulic actuator are the same hydraulic drive source. Cavity type toroidal type continuously variable transmission.