JPH0725452Y2 - Bearing device that rotatably supports the inner shaft inside the outer shaft - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a co-rotating bearing in a double rotating shaft.

[Conventional technology]

FIG. 4 shows a conventional example of a bearing structure in which a shaft and a bearing rotate in the same direction. Reference numeral 2 denotes an inner shaft that rotates in a fixed direction, and a bearing 3 that supports the inner shaft 2 is fixed to the inner surface of the outer shaft 1. The outer shaft 1 rotates in the same direction as the inner shaft 2. Therefore, the bearing 3
Will rotate in the same direction as the inner shaft 2.

The outer shaft 1 is supported by a bearing 4 which is stationary. 3a, 4
Each a indicates a lining layer of bearing metal (white metal, etc.). Reference numerals 5 and 8 are oil grooves provided annularly in the circumferential direction on the bearing surface, and reference numeral 7 is a circumferential oil groove provided on the back surface of the bearing 3. 6 is an oil supply hole for communicating the circumferential oil grooves 5 and 6 of the bearing 3, and 10 is an oil supply hole provided in the outer shaft 1 in a number of 1 or more, to connect the circumferential oil grooves 8 and 7 with each other. There is. Reference numeral 9 denotes an oil supply hole provided in the bearing 4, which guides oil supply from an external oil supply line (not shown) to the circumferential oil groove 8 of the bearing 4.

Oil supply to the rotating bearing 3 is performed by the following route.

The lubricating oil supplied from the outside passes through the oil supply hole 9 and passes through the bearing 4
Reaching the circumferential oil groove 8 and passing through the oil hole 10, the circumferential groove 7 and the oil hole 6 provided in the outer shaft 1 to the circumferential oil groove 5 provided in the bearing surface of the bearing 3. come.

[Problems to be solved by the device]

The above-mentioned conventional technique has the following problems. Although the lubricating oil reaches the circumferential oil groove 5, since the bearing surface of the bearing 3 has no axial oil groove, the oil does not easily spread in the axial direction, and a sufficient amount of oil necessary for fluid lubrication is provided. Insufficient oil film thickness is not formed.

If the bearing surface is provided with an axial oil groove similar to the conventional bearing in order to solve the oil shortage, the load capacity will be significantly reduced.
Because the bearing 3 is rotating, the load surface of the bearing 3 is not constant and changes with rotation. When the axial oil groove is on the load surface (which is necessary once per one rotation), the oil groove causes the fluid lubrication action to disappear, leading to a reduction in the oil film thickness.

Another solution to the shortage of oil quantity is to increase the hydraulic pressure, but it requires a high-pressure oil source and is not a preferable measure from the viewpoint of cost and reliability.

It is an object of the present invention to provide a bearing structure that does not reduce the load capacity and that does not cause an oil shortage in low-pressure oil supply.

[Means for Solving the Problems]

A plurality of pockets (axial grooves) are provided on the bearing surface, and these pockets communicate with the oil supply groove provided on the back surface of the bearing.

The length of the pocket in the axial direction should be about 1/2 of the total width of the bearing to ensure the axial spread of the lubricating oil in the bearing surface.

Place the pockets alternately on one side of the bearing width.

[Action]

Even if the bearing load surface becomes the surface with the pocket,
One side of the entire bearing width, which has no pocket, has a fluid lubrication action, so that the oil film thickness is not reduced or is not significantly reduced.

〔Example〕

 A first embodiment of the present invention is shown in FIG.

2 is an inner shaft that rotates, and 1 is a hollow outer shaft that rotates in the same direction as the inner shaft 2. A fixed outer shaft support bearing 4 rotatably supports the outer shaft 1, and an inner shaft support bearing 3 is fixed to the inner surface of the outer shaft 1. On the bearing surface of the bearing 3, pockets (axial grooves) 11a, 11b are arranged at 180 ° opposing positions in the circumferential direction and on opposite side sides in the bearing width direction. A development view of the bearing surface of the bearing 3 is shown in FIG. Pocket 11a, 11b
Are respectively connected to the bearing rear circumferential oil groove 7 by oiling holes 6a and 6b.

The bearing 4 is a stationary bearing that supports the outer shaft 1. The bearing surface has a circumferential oil groove 8 and is connected to an external oil supply line by an oil supply hole 9. The circumferential oil grooves 8 and 7 are communicated with each other through a plurality of oil supply holes 10 provided in the outer shaft 1.

The lubricating oil supplied from the oil supply hole 9 is the circumferential oil groove 8 and the oil supply hole 10.
To the circumferential oil groove 7 on the back surface of the bearing 3. The oil in the circumferential oil groove 7 passes through the communication holes 6a and 6b, and the bearing surface pocket 1
It is filled with 1a and 11b.

The pocket 11a spreads over one half of the bearing in the axial direction and supplies oil to one half of the bearing. The pocket 11b is spread over one half on the opposite side of the pocket 11a and supplies oil to this half. In this way, the pocket 11
At a and 11b, the oil required for fluid lubrication is supplied to all bearing surfaces.

Since the bearing 3 is rotating, the load surface that bears the bearing load changes in the circumferential direction during one rotation. Pocket
Even if the surface with 11a or pocket 11b becomes the load surface,
Since there is no pocket in one half of the bearing, the fluid lubrication function occurs in one half, and the decrease in oil film thickness is smaller than that with an axial oil groove over the entire width of the bearing, and the bearing function is sufficient. Have.

In the first embodiment, the oil groove on the back surface of the bearing is the circumferential oil 7. However, instead of the circumferential groove 7, an axial oil groove is provided on the back surface of the bearing, and the same effect can be obtained by communicating with the pockets 11a and 11b. effective.

A second embodiment of the present invention is shown in FIG.

Along with the circumferential oil groove on the back surface of the bearing 3, a circumferential oil groove 5 is provided on the bearing surface so as to communicate with the pockets 11a and 11b.
(In this case, the pockets 11a and 11b are axial oil grooves rather than pockets.) In this case, the second embodiment is more suitable for the circumferential oil groove 5 than the first embodiment.
Therefore, the load capacity is inferior, but it has the same operation and effect as those of the first embodiment.

[Effect of device]

A bearing device for rotatably supporting an inner shaft inside an outer shaft according to the present invention comprises a hollow outer shaft rotatably supported by a fixed bearing, and an inner shaft rotatably provided inside the outer shaft. A bearing device comprising an inner shaft support bearing fixed to the inner peripheral surface of the outer shaft to support the inner shaft, and a lubricating oil passage extending from the fixed bearing to the inner shaft support bearing, the bearing of the inner shaft support bearing By arranging on the surface, a pair of pockets communicating with the lubricating oil passage and extending in the axial direction of about 1/2 of the entire bearing width are arranged on the opposite side in the bearing width direction and on the opposite side in the circumferential direction. , Has the following effects.

(A) Since a pair of axial pockets each having a length about ½ of the entire bearing width are provided in the bearing width direction, the lubricating oil is supplied over the entire width of the inner shaft support bearing.

(B) Even if the bearing load surface is the surface provided with the pocket, one side of the entire bearing width without the pocket performs fluid lubrication.

Therefore, the decrease in the oil film thickness is extremely small.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a bearing device according to a first embodiment of the present invention,
FIG. 2 is a developed view of the bearing surface of the above, FIG. 3 is a developed view of the bearing surface according to the second embodiment of the present invention, and FIG. 4 is a sectional view of a conventional device. DESCRIPTION OF SYMBOLS 1 ... Outer shaft, 2 ... Inner shaft 3 ... Inner shaft support bearing, 4 ... Outer shaft support bearing 5 ... Circular oil groove, 6 ... Oil supply hole 7 ... Bearing back circumferential oil groove, 8 ... Circular oil groove 9 ... Refueling hole, 10 ... Refueling hole 11a, 11b ... Pocket

Claims (1)

[Scope of utility model registration request] 1. A hollow outer shaft rotatably supported by a fixed bearing, an inner shaft rotatably provided inside the outer shaft, and an inner shaft fixed to an inner peripheral surface of the outer shaft. In a bearing device comprising an inner shaft supporting bearing to support and a lubricating oil passage extending from the fixed bearing to the inner shaft supporting bearing, a bearing surface of the inner shaft supporting bearing communicates with the lubricating oil passage and a bearing full width About
A pair of pockets extending in the axial direction of 1/2 are arranged on the opposite side in the bearing width direction and on the opposite side in the circumferential direction, respectively. The inner shaft is rotatably supported inside the outer shaft. Bearing device.