JP2003184873A - Bearing equipment for automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate pre-load control by minimizing pre-load variation in the pivot bearing equipment for supporting the gearing shaft provided with an automatic transmission for vehicles. <P>SOLUTION: Double row outward conical roller bearing 1 equipped on the small diameter section of an output shaft 2 is fixed and sandwiched by a nut 4 that is attached on the shaft extension of the small diameter section and further a ring-shaped plate spring 3 is provided between the side wall 21 of the output shaft 2 and the double row outward conical roller bearing 1. Therefore, the required pre-load is given to the double row outward conical roller bearing 1 by the elastic restoration force of the ring-shaped plate spring 3. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support shaft device for supporting a gear shaft provided in an automatic transmission for a vehicle.

[0002]

2. Description of the Related Art Conventionally, a double row outward tapered roller bearing or a roller bearing is used for supporting an input shaft or an output shaft as a gear shaft of an automatic transmission for a vehicle where a high load acts and axial positioning is required. Double-row outward contact angular contact ball bearings such as angular contact ball bearings are used. Although a preload is applied to these bearings, the method of applying this preload is usually a fixed position preload that can ensure high rigidity.

[0003]

By the way, in the above-mentioned conventional example, since the fixed position preload is set by the fitting amount of the inner ring or the outer ring, the bearing clearance, the assembly width dimension, etc., the dimensional tolerance of each part is set. Must be taken into consideration, and preload management is troublesome. Further, the preload changes due to the temperature change after mounting and the increase / decrease of the applied load, which makes it difficult to set the proper preload.

Accordingly, it is an object of the present invention to reduce preload fluctuation and facilitate preload management in a support shaft device for supporting a gear shaft provided in an automatic transmission for a vehicle.

[0005]

According to a first aspect of the present invention, there is provided a bearing device for an automatic transmission, which is externally fitted to a gear shaft of an automatic transmission so that the gear shaft is rotatable. A bearing device comprising an oblique contact type rolling bearing to be supported, wherein a required preload is applied to the oblique contact type rolling bearing in the form of a constant pressure preload.

A bearing device for a second automatic transmission according to the present invention is
A double-row outward rolling bearing that is externally fitted to a gear shaft of an automatic transmission and includes a double-row outward rolling bearing that rotatably supports the gear shaft. Has a single outer ring having two rows of rolling surfaces and two inner rings, and the required preload is applied to the double row outward rolling bearing in the form of constant pressure preload.

A bearing device for a third automatic transmission according to the present invention is
4. A bearing device comprising a double row outward rolling bearing externally fitted to a gear shaft of an automatic transmission and rotatably supporting the gear shaft according to claim 3, wherein the double row outward rolling bearing is provided. Has a single outer ring having two rows of rolling surfaces, and two inner rings, the gear shaft has a small diameter portion on the shaft end side, and the double row outward rolling bearing has a small diameter portion on the small diameter portion. The two inner rings of the double-row outward rolling bearing that are externally mounted are provided with a side wall surface on the boundary between the small diameter portion and the large diameter portion of the gear shaft, and a fixing member attached to the shaft end side of the small diameter portion of the gear shaft. An elastic body that is sandwiched in the axial direction and that provides an elastic urging force in a direction to bring the two inner rings close to each other between the side wall surface of the gear shaft and the one inner ring or between the fixing member and the other inner ring. Is installed.

A bearing device for a fourth automatic transmission according to the present invention is
5. A bearing device including a double row outward rolling bearing externally fitted to a gear shaft of an automatic transmission and rotatably supporting the gear shaft according to claim 4, wherein the double row outward rolling bearing is provided. Has a single outer ring having two rows of rolling surfaces, and two inner rings, the gear shaft has a small diameter portion on the shaft end side, and the double row outward rolling bearing has a small diameter portion on the small diameter portion. The two inner rings of the double-row outward rolling bearing that are externally mounted are provided with a side wall surface on the boundary between the small diameter portion and the large diameter portion of the gear shaft, and a fixing member attached to the shaft end side of the small diameter portion of the gear shaft. It is sandwiched in the axial direction, and while applying an elastic urging force in the direction of approaching to the other side to one of the two inner rings by hydraulic pressure,
A preload adjusting mechanism for controlling the hydraulic pressure is provided as needed.

A bearing device for a fifth automatic transmission according to the present invention is
A double row outward rolling bearing, which is externally fitted to a gear shaft of an automatic transmission and rotatably supports the gear shaft, wherein the double row outward rolling bearing is provided. Has a single outer ring having two rows of rolling surfaces, and two inner rings, the gear shaft has a small diameter portion on the shaft end side, and the double row outward rolling bearing has a small diameter portion on the small diameter portion. The two inner rings of the double-row outward rolling bearing that are externally mounted are provided with a side wall surface on the boundary between the small diameter portion and the large diameter portion of the gear shaft, and a fixing member attached to the shaft end side of the small diameter portion of the gear shaft. It is sandwiched in the axial direction, and while applying an elastic urging force in the direction of approaching to the other side to one of the two inner rings by hydraulic pressure,
A preload adjusting mechanism for controlling the hydraulic pressure is provided as needed, and the preload adjusting mechanism supplies lubricating oil to a predetermined portion of the automatic transmission in accordance with a change in drive torque output from the automatic transmission. And a hydraulic pump for automatically changing and controlling the supply pressure of the lubricating oil, and the supply pressure of the lubricating oil controlled by the hydraulic pump is applied as the elastic urging force, and the elastic urging force is changed according to the supply pressure. And a pressing element.

A bearing device for a sixth automatic transmission according to the present invention is
As described in claim 6, in the fifth aspect, the pressing element is interposed between the side wall surface of the gear shaft and one inner ring or between the fixing member and the other inner ring, A cylinder ring body that is in contact with the side wall surface side or the fixing member side, and an axial center with respect to the cylinder ring body in a state in which a hydraulic chamber through which the lubricating oil flows in and out is formed. A piston ring body that is slidably mounted in a direction, and a lubricating oil flow path from the hydraulic pump to the hydraulic chamber is provided on the gear shaft.

In short, according to the present invention, the preload is applied to the oblique contact type rolling bearing which supports the gear shaft of the automatic transmission by the constant pressure preload, so that the constant position preload is used as in the conventional example. Pre-load management becomes easy without considering the dimensional tolerance of parts.

In particular, the second structure limits the oblique contact type rolling bearing in the first aspect to a double row outward rolling bearing.

The third structure uses an elastic body as an example of the constant pressure preload mode in the double row outward rolling bearing.

Further, in the above-mentioned fourth structure, by providing the preload adjusting mechanism by the hydraulic control, the preload of the double row outward rolling bearing can be easily adjusted.

In the fifth structure, the preload adjusting mechanism in the fourth structure is composed of a hydraulic pump for supplying lubricating oil to a predetermined portion of the automatic transmission and a pressing element controlled by the hydraulic pump. It is a thing.

In the sixth structure, the pressing element in the fifth structure is limited to the structure of the piston ring body and the cylinder ring body, and the lubricating oil is supplied from the hydraulic pump communicating with the hydraulic chamber of the pressing element. The passage was secured.

[0017]

DETAILED DESCRIPTION OF THE INVENTION The details of the present invention will be described below with reference to the embodiments shown in the drawings.

FIG. 1 is an upper half sectional view showing a bearing device for supporting an output shaft of an automatic transmission for a vehicle according to a first embodiment of the present invention.

The double row outward tapered roller bearing 1 of the illustrated example is externally fitted and mounted on an output shaft 2 as a gear shaft in an automatic transmission for a vehicle, and rotatably supports the output shaft 2.

The double row outward tapered roller bearing 1 comprises a single outer ring 11, a plurality of tapered rollers 12, two cages 13,
It has two inner rings 14.

The outer race 11 has two rows of outer raceways 16 on the inner circumference.
have.

The tapered rollers 12 are the two rows of outer ring rolling surfaces 1 described above.
A plurality of them are arranged on the 6 in the circumferential direction.

The cage 13 rotatably retains the tapered rollers 12 in each row.

The inner ring 14 has one row of inner ring rolling surfaces 17 that are paired with the two rows of outer ring rolling surfaces 16 of the outer ring 11, and are arranged side by side in the axial direction.

An output gear 19 is provided on the outer periphery of the outer ring 11, and the output gear 19 is provided.
Is configured to transmit or cut off power by rotating relative to or synchronously with the output shaft 2 by a shift operation of an automatic transmission or the like.

In the first embodiment, the required preload is applied to the double row outward tapered roller bearing 1 in the form of constant pressure preload.

Specifically, a double row outward tapered roller bearing 1 is externally mounted on the small diameter portion of the output shaft 2 on the axial end side, and two inner rings 14 of the double row outward tapered roller bearing 1 are provided.
Is axially sandwiched by the side wall surface 21 at the boundary between the small diameter portion and the large diameter portion of the output shaft 2 and the nut 4 attached to the shaft end side of the small diameter portion of the output shaft 2.

Further, an annular leaf spring (disc spring) 3 is interposed between the side wall surface 21 of the output shaft 2 and one of the two inner rings 14 while being elastically compressed in the axial direction. ing.

A spacer 15 is interposed between the two inner races 14 of the double row outward tapered roller bearing 1.

The axial length of the spacer 15 is set in accordance with the axial gap between the two inner races 14,
This gap is based on a state in which an appropriate preload is applied to the double-row outward tapered roller bearing 1. In other words, the spacer 15 is
While allowing a proper preload on the double row outward tapered roller bearing 1,
It is designed to prevent excessive preload.

In the above embodiment, the amount of elastic compression of the annular leaf spring 3 is adjusted by tightening the nut 4. Therefore, a required preload is applied to the double row outward tapered roller bearing 1 by the elastic restoring force of the annular leaf spring 3.

Here, if the output shaft 2 is thermally expanded, the annular leaf spring 3 is elastically restored,
When the output shaft 2 is thermally contracted, the annular leaf spring 3 is elastically compressed, so that the preload on the double-row outward tapered roller bearing 1 is kept constant.

Further, when the heat shrinkage of the output shaft 2 is abnormally large, the two inner rings 1 due to the spacer 15 are used.
Since the annular leaf springs 3 are prevented from coming too close to each other, the annular leaf spring 3 is not compressed too much, and the annular leaf spring 3 is prevented from being plastically deformed and the elastic restoring force being abnormally lowered.

As described above, since the required preload is applied in the form of constant pressure preload to the double row outward tapered roller bearing 1 that supports the output shaft 2 in the automatic transmission for a vehicle, the conventional example is used. Compared with the case of using the constant position preload mode, the dimensional tolerance of parts is not considered,
Preload management becomes easy.

Further, since there is no change in the preload due to a change in temperature after assembly and an increase / decrease in applied load, an appropriate preload can always be maintained.

FIG. 2 is an upper half sectional view showing a spindle device of an output shaft of an automatic transmission for a vehicle according to a second embodiment of the present invention.

In the second embodiment, the above-mentioned first embodiment is used.
The configuration different from the double row outward tapered roller bearing 1 is that a preload adjusting mechanism is provided. Other configurations are basically the same.

Specifically, between the side wall surface 21 at the boundary between the small diameter portion and the large diameter portion of the output shaft 2 and the one inner ring,
The preload changer 6 as the pressing element according to claim 5 is interposed.

The preload changer 6 comprises a metallic piston ring 6
1 and a cylinder ring body 62.

The piston ring body 61 and the cylinder ring body 62 are
In both of them, the cross sections of the upper halves are formed in a substantially inverted L shape, and the annular plate portions 66 and 68 and the cylindrical portions 67 and 69, respectively.
It consists of and. The piston ring body 61 and the cylinder ring body 62 are arranged so that the respective cylindrical portions 66 and 67 face each other, and are fitted with a slight gap between inside and outside in the radial direction.

These piston ring body 61 and cylinder ring body 6
The space surrounded by 2 is a hydraulic chamber 65.

A peripheral groove is provided on the outer peripheral surface of the base of the cylindrical portion of the piston ring 61, and an O-ring 71 is fitted therein. Further, circumferential grooves are also provided on the inner circumferences of the annular plate portions 66, 68 of the piston ring body 61 and the cylinder ring body 62, and O-rings 72 are fitted therein.

A return spring 15 such as a disc spring is installed between the two inner rings 14.

By the way, a lubricating oil passage 5 is provided at the axial center of the output shaft 2 so as to penetrate therethrough in the axial direction. Lubricating oil is supplied to the lubricating oil passage 5 by a hydraulic pump (not shown).

A hydraulic chamber 65 of the preload changer 6 penetrates through the lubricating oil flow path 5 in a radially outward direction.
A through hole 51 that opens to the bottom is provided.

The preload changing device 6, the through hole 51, the lubricating oil flow path 5, and the hydraulic pump (not shown) constitute the preload adjusting mechanism.

The operation of the preload adjusting mechanism having the above structure is as follows.
It is as follows.

The hydraulic chamber (65) of the hydraulic pump (not shown) and the preload changer 6 includes the lubricating oil flow path 5 and the output shaft 2.
Since it is connected to the hydraulic chamber 65 of the preload changer 6, the supply pressure of the lubricating oil from a hydraulic pump (not shown) is applied. With this supply pressure,
The piston ring body 61 is axially separated from the cylinder ring body 62 that is in contact with the side wall surface 21 of the output shaft 2, and the two inner rings 14 are elastically biased toward each other ( Axial load) is applied to preload the double row outward tapered roller bearing 1.

When the internal pressure of the hydraulic chamber 65 drops, the return spring 15 installed between the two inner rings 14 causes the inner ring 14 on the enlarged diameter side of the output shaft 2 to
The occurrence of a gap (preload loss phenomenon) between the preload changer 6 and the piston ring 61 is prevented.

By the way, the supply pressure of the lubricating oil applied to the hydraulic chamber 65 of the preload changer 6 is controlled by a hydraulic pump (not shown) according to the increase or decrease of the drive torque output from the automatic transmission. . In other words, if the driving torque increases,
When the supply pressure of the lubricating oil to the hydraulic chamber 65 also rises and the driving torque decreases, the supply pressure of the lubricating oil to the hydraulic chamber 65 also lowers.

Specifically, when the driving force is output by the low gear of the transmission when the vehicle starts or accelerates, the engine speed increases and the driving torque also increases. The supply pressure of the lubricating oil increases, and the preload applied to the double row outward tapered roller bearing 1 increases.

On the other hand, when the vehicle is stopped or running normally,
Although the engine speed will decrease and the drive torque will also decrease,
Along with this, the supply pressure of the lubricating oil to the hydraulic chamber 65 decreases, and the preload applied to the double row outward tapered roller bearing 1 decreases.

As described above, by providing the preload adjusting mechanism 6, the lubricating oil flow path 5, the through hole 51 of the output shaft 2 communicating therewith, and the preload adjusting mechanism including the hydraulic pump (not shown). The preload on the double-row outward tapered roller bearing 1 can be automatically and appropriately controlled according to the increase / decrease in the driving torque output from the automatic transmission.

That is, when the driving torque increases, such as when the vehicle starts or accelerates, the preload applied to the double row outward tapered roller bearing 1 can be appropriately increased, so that the double row outside The rigidity of the tapered roller bearing 1 is increased, and stable acceleration and operation of the vehicle can be secured.

Further, when the driving torque is reduced such as when the vehicle is stopped or when the vehicle is running steadily, the preload applied to the double row outward tapered roller bearing 1 can be appropriately lowered, so that the sliding Resistance can be reduced, leading to improved fuel economy and quietness of the vehicle.

Moreover, for the preload control of the double-row outward tapered roller bearing 1, it is not necessary to separately provide a special sensor or control system.

The present invention is not limited to the above embodiment, and various applications and modifications can be considered.

(1) In Embodiments 1 and 2 described above, a double row outward tapered roller bearing can be used in place of the double row outward tapered roller bearing 1, and two single row oblique contact rolling bearings can be combined. It can also be used.

(2) In the first embodiment, instead of the annular leaf spring 3, a coil spring or any other elastic body can be used.

(3) In the first embodiment, the annular leaf spring 3 may be installed at any position in the axial direction. For example,
For example, the annular leaf spring 3 is installed between the nut 4 and the inner ring 14.

(4) In the second embodiment, the preload changer 6
Was installed between the side wall surface 21 of the output shaft 2 and one of the inner rings 14, but instead of this, the preload changer 6 is installed between the nut 4 and the inner ring 14. Good.

(5) In the second embodiment, the preload changer 6 may be separated from the lubricating oil system in the automatic transmission and a separate control system may be provided. In this case, for example,
It suffices to equip a sensor for detecting the driving torque and use a controller or the like that controls the operation of the preload changer 6 based on the sensor output.

(6) In the second embodiment, the preload changer 6 may be replaced with the following configuration.

That is, the inner ring 14 on the large diameter side of the output shaft 2 is used as a piston, and the output shaft 2 is used as a cylinder.

Concretely, in FIG. 4, a cylindrical portion 18 extending in the axial direction is formed at the end of the inner ring 14 on the large diameter portion side of the output shaft 2 on the large diameter portion side end of the output shaft 2. .

The inner diameter of the cylindrical portion 18 is equal to that of the inner ring 14.
Is larger than the minimum inner diameter portion of the inner ring 14 and has the same outer diameter as the maximum outer diameter of the inner ring 14.

A hydraulic chamber 22 is formed in a space surrounded by the inner ring 14 and the cylindrical portion 18 thereof, the outer peripheral surface of the output shaft 2 and the side wall surface 21 thereof, and a lubricating oil from a hydraulic pump (not shown) is formed. Supply pressure is applied.

A peripheral groove is provided on the outer peripheral surface of the large-diameter portion of the output shaft 2, and the O-ring 7 is provided there.
3 is fitted and contacts the inner peripheral surface of the cylindrical portion 18. Also,
A peripheral groove is also provided on the inner peripheral surface of the inner ring 14 on the large diameter portion side of the output shaft 2, and an O-ring 74 is fitted therein to contact the outer peripheral surface of the small diameter portion of the output shaft 2.

In the above structure, the supply pressure of the lubricating oil from the hydraulic pump (not shown) is applied to the hydraulic chamber 22, so that the inner ring 14 on the large diameter side of the output shaft 2 is provided.
Is in a state of being separated from the side wall surface 21 of the output shaft 2 in the axial direction, so that the two inner races 14 apply a resilient urging force in a direction in which they approach each other.

[0070]

As described above, in the bearing device for an automatic transmission according to claims 1 to 3, the preload is applied to the oblique contact type rolling bearing that supports the gear shaft of the automatic transmission by constant pressure preload. Therefore, compared to the case of using the constant position preload as in the conventional example, it is not necessary to consider the dimensional tolerance of the parts, and the preload management becomes easier. Further, since there is no change in preload due to a change in temperature after assembly or an increase / decrease in applied load, an appropriate preload can always be maintained. Therefore, this contributes to maintenance-free maintenance of the bearing device of the automatic transmission.

Further, in the bearing device for an automatic transmission according to claim 4, by providing a preload adjusting mechanism by hydraulic control,
The preload of the double-row outward rolling bearing can be easily adjusted. Therefore, even if a change in preload occurs due to a change in temperature after assembly or an increase / decrease in applied load, readjustment can be easily performed.

Further, in the bearing device for an automatic transmission according to a fifth aspect, originally, the hydraulic pump for automatically changing and controlling the supply pressure of the lubricating oil supplied to a predetermined portion of the automatic transmission is the preload adjusting mechanism. Since it is used to control the hydraulic pressure of the automatic transmission, the preload on the double row outward tapered roller bearing can be automatically and appropriately controlled according to the increase or decrease of the drive torque output from the automatic transmission. There is no need to install separate sensors and control system separately.

Further, in the bearing device for an automatic transmission according to claim 6, since the pressing element according to claim 5 is constituted by a piston ring body and a cylinder ring body, the bearing device is relatively simple. Manufacturing cost can be reduced. Furthermore, since the gear shaft is provided with a passage for lubricating oil supply from the hydraulic pump that communicates with the hydraulic chamber of the pressing element, it is not necessary to externally attach a lubricating oil supply passage, etc., and the number of assembly steps is reduced. The manufacturing cost of the bearing device can be reduced.

[Brief description of drawings]

FIG. 1 is an upper half sectional view showing a bearing device for supporting an output shaft of an automatic transmission for a vehicle according to a first embodiment of the present invention.

FIG. 2 is an upper half sectional view showing a spindle device for an output shaft of an automatic transmission for a vehicle according to a second embodiment of the present invention.

3 is a cross-sectional view of the main part of FIG.

FIG. 4 is an upper half sectional view showing a spindle device for an output shaft of an automatic transmission for a vehicle according to another embodiment of the present invention.

[Explanation of symbols]

1 Double row outward tapered roller bearing 2 Output shaft 3 annular leaf spring 4 nuts 21 Side wall surface

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 3J012 AB02 AB04 AB11 BB03 CB03                       CB05 DB09 DB14 FB12 GB10                       HB02                 3J063 AA01 AC04 BA04 BA07 BB27                       CA01 CB41 CD03 CD06                 3J101 AA16 AA25 AA32 AA43 AA54                       AA62 FA41 GA11

Claims (6)

[Claims] 1. A bearing device which is externally fitted to a gear shaft of an automatic transmission and includes an oblique contact rolling bearing that rotatably supports the gear shaft, wherein the oblique contact rolling bearing has a constant pressure preload mode. A bearing device for an automatic transmission, characterized in that a required preload is applied to the bearing device. 2. A bearing device comprising a double row outward rolling bearing externally fitted to a gear shaft of an automatic transmission and rotatably supporting the gear shaft, wherein the double row outward rolling bearing comprises: An automatic transmission characterized by having a single outer ring having a row rolling surface and two inner rings, wherein the double row outward rolling bearing is provided with a required preload in the form of a constant pressure preload. Bearing device. 3. A bearing device comprising a double row outward rolling bearing externally fitted to a gear shaft of an automatic transmission and rotatably supporting the gear shaft, wherein the double row outward rolling bearing comprises: It has a single outer ring having a row rolling surface and two inner rings, the gear shaft has a small diameter portion on the shaft end side, and the double row outward rolling bearing is externally mounted on the small diameter portion. The two inner rings of the double-row outward rolling bearing are axially formed by a side wall surface of a boundary between the small diameter portion and the large diameter portion of the gear shaft and a fixing member attached to the shaft end side of the small diameter portion of the gear shaft. An elastic body that is sandwiched between the side wall surface of the gear shaft and one inner ring or between the fixing member and the other inner ring and that provides an elastic biasing force in the direction of bringing the two inner rings close to each other is interposed. A bearing device for an automatic transmission, which is characterized in that 4. A bearing device comprising a double row outward rolling bearing externally fitted to a gear shaft of an automatic transmission and rotatably supporting the gear shaft, wherein the double row outward rolling bearing comprises: It has a single outer ring having a row rolling surface and two inner rings, the gear shaft has a small diameter portion on the shaft end side, and the double row outward rolling bearing is externally mounted on the small diameter portion. The two inner rings of the double-row outward rolling bearing are axially formed by a side wall surface of a boundary between the small diameter portion and the large diameter portion of the gear shaft and a fixing member attached to the shaft end side of the small diameter portion of the gear shaft. A preload adjusting mechanism that is sandwiched between the two inner rings and that applies a resilient biasing force to the other side by hydraulic pressure and that controls the hydraulic pressure as necessary is provided. Bearing device for automatic transmission characterized by: 5. A bearing device comprising a double row outward rolling bearing externally fitted to a gear shaft of an automatic transmission and rotatably supporting the gear shaft, wherein the double row outward rolling bearing comprises: It has a single outer ring having a row rolling surface and two inner rings, the gear shaft has a small diameter portion on the shaft end side, and the double row outward rolling bearing is externally mounted on the small diameter portion. The two inner rings of the double-row outward rolling bearing are axially formed by a side wall surface of a boundary between the small diameter portion and the large diameter portion of the gear shaft and a fixing member attached to the shaft end side of the small diameter portion of the gear shaft. Is sandwiched, while applying a resilient biasing force in the direction of approaching to the other side to one of the two inner rings by hydraulic pressure, a preload adjusting mechanism for controlling the hydraulic pressure is provided as necessary, The preload adjustment mechanism changes the drive torque output from the automatic transmission. A hydraulic pump for automatically changing and controlling the supply pressure of the lubricating oil supplied to a predetermined portion of the automatic transmission, and the supply pressure of the lubricating oil controlled by this hydraulic pump is applied as the elastic urging force. A bearing device for an automatic transmission, comprising: a pressing element that changes the elastic biasing force according to the supply pressure. 6. The bearing device for an automatic transmission according to claim 5, wherein the pressing element is interposed between the side wall surface of the gear shaft and one inner ring or between the fixing member and the other inner ring. In the state where a cylinder annular body that is in contact with the side wall surface side or the fixed member side and a hydraulic chamber through which the lubricating oil flows in and out are formed between the cylinder annular body and the cylinder annular body. And a piston ring body that is slidably mounted in the axial direction, and a lubricating oil flow path from the hydraulic pump to the hydraulic chamber is provided on the gear shaft. Bearing device.