JPH0658328A - Floating bush bearing - Google Patents

Abstract

PURPOSE:To provide a floating bush bearing which can decrease self-excited vibration caused by dynamic pressure of outside oil film. CONSTITUTION:A groove 11 which extends circularly in the fixed depth from the upper part of a bearing face 4 in reverse rotational direction of a shaft 1, is formed, a pocket 13 to which a filler opening 12 is communicated at the starting terminal in the rotational direction A of the shaft 1, is formed, and a step part 14 is formed at the end terminal. Oil 7 supplied from the filler opening 12 flows in the groove 11 from the pocket 13 in the rotational direction A of the shaft 1, by viscosity of outer oil film 9 which acts by rotation of a bush 2 to rotate together with the shaft 1, and as it approaches the step part 14 formed at the end terminal in the direction A, system is dammed and dynamic pressure is generated. When self-excited vibration occurrs by being by dynamic pressure to act on the outer oil film 9 on the under side this dynamic pressure increases or decreases in response to that vibration in order to depress the vibration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a floating bush bearing.

[0002]

2. Description of the Related Art FIGS. 4 and 5 show an example of a conventional floating bush bearing. In the figures, 1 is a shaft which is rotationally driven in the direction of arrow A, and 2 is a required clearance in the outer peripheral portion of the shaft 1. Cylindrical bushes 4, which are loosely fitted to each other and have a plurality of through holes 3 communicating with the inner and outer sides in the circumferential direction, are formed in the bushes 2.
Shows a bearing surface formed so as to surround the bearing with a required clearance, and a pocket 5 having a crescent-shaped cross section is formed in an upper portion of the bearing surface 4, and an oil supply hole 6 is communicated with the pocket 5.

When oil is supplied from the oil supply hole 6,
The oil 7 that has been supplied is introduced from the outer peripheral side of the bush 2 into the through holes 3
Is guided to the inner peripheral side through and the space between the bearing surface 4 and the shaft 1 is filled with oil 7.

When the shaft 1 is rotationally driven in the direction of the arrow A in such a state, the viscosity of the oil 7 forms an inner oil film 8 between the shaft 1 and the bush 2, and the bush rotates along with the rotation of the shaft 1. Since the outer oil film 9 is also formed between the oil film 2 and the fixed bearing surface 4, the shaft 1 is supported by the bush 2 floating between the oil films 8 and 9.

In the floating bush bearing as described above, the stability of the shaft 1 increases as the bearing load increases,
Conventionally, the shaft 1 and the bush 2 are pushed down by the hydraulic pressure supplied from the pocket 5 to apply a load, thereby increasing the eccentricity of the shaft 1 and pushing down the shaft 1 and the bush 2 lowers both oil films 8 and 9. The shaft 1 is balanced by the balance between the push-up force due to the static pressure on the lower side of both oil films 8 and 9 which is boosted by narrowing the flow path in the rotation direction of the shaft 1 and the total load of the hydraulic pressure and the own weight of the shaft 1. I was trying to stabilize.

[0006]

However, the stabilization of the shaft 1 by the above-mentioned conventional method is considered only as a balance between upper and lower static pressures, and the outer oil film below the alternate long and short dash line shown in FIG. However, there is a drawback in that there is no restraint force for self-excited vibration caused by the dynamic pressure acting in 9.

The present invention has been made in view of the above situation, and an object thereof is to provide a floating bush bearing capable of reducing self-excited vibration due to dynamic pressure of an outer oil film.

[0008]

According to the present invention, a groove portion extending in an arc shape from the upper portion of a bearing surface toward the counter-rotational direction of a shaft at a constant depth is formed, and the starting end of the groove portion in the rotational direction of the shaft is formed. The present invention relates to a floating bush bearing characterized in that a pocket communicating with the oil supply hole and a stepped portion are formed at the ends thereof.

[0009]

Therefore, according to the present invention, the oil supplied from the oil supply hole flows from the pocket in the groove in the rotational direction of the shaft due to the viscosity of the outer oil film that acts due to the rotation of the bush that circulates around the shaft, and the end of that direction is reached. The flow is dammed as it approaches the step formed in the above, and dynamic pressure is generated, and this dynamic pressure responds immediately to the self-excited vibration caused by the dynamic pressure that acts on the lower outer oil film. Increase or decrease to suppress vibration.

Further, the oil in the groove portion is fed from the pocket toward the step portion of the dead end, whereby the static pressure is also increased. As a result, the force of pushing down the shaft acts, and the stability of the shaft due to the balance between the upper and lower static pressures is also enhanced.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show an embodiment of the present invention, in which parts designated by the same reference numerals as those in FIG. 4 represent the same parts.

In a floating bush bearing 10 having a shaft 1, a bush 2, and a bearing surface 4 in substantially the same manner as the floating bush bearing of FIG. 4 described above, the direction of counter rotation of the shaft 1 from the upper portion of the bearing surface 4 (arrow A). A groove portion 11 extending in a circular arc shape with a constant depth in the opposite direction) is formed, a pocket 13 is formed at the start end of the groove portion 11 in the rotation direction of the shaft 1 and a pocket 13 is connected to the oil supply hole 12, and a step is formed at the end. The part 14 is formed.

Here, the depth of the groove 11 is set to such a degree that the viscosity of the oil 7 becomes dominant.

Reference numeral 15 in the drawing is formed on both sides in the width direction (longitudinal direction of the shaft) of the pocket 13 so that the newly introduced oil 7 stays in the pocket 13 and the groove portion 11 so that the oil supply is not delayed. The oil supply branch groove is shown.

Thus, the oil 7 supplied from the oil supply hole 12
Due to the viscosity of the outer oil film 9 acting due to the rotation of the bush 2 rotating around the shaft 1
Flows in the shaft 1 in the rotation direction of the shaft 1 (direction of arrow A), and as it approaches the step portion 14 formed at the end of the shaft 1, the flow is blocked and a dynamic pressure is generated.

When the self-excited vibration caused by the dynamic pressure acting on the outer oil film 9 on the lower side is generated, the dynamic pressure is increased or decreased so as to suppress the vibration in response to the self-excited vibration.

That is, as shown in FIG. 3, when the shaft 1 and the bush 2 are pushed up to the groove portion 11 side by the dynamic pressure of the lower portion of the outer oil film 9 and come close to each other, the gap between the downstream side bearing surface 4 of the step portion 14 and the bush 2 is increased. The merging portion x is narrowed to increase the dynamic pressure on the upper side, so that the shaft 1 is pushed back downward through the bush 2. Further, when the shaft 1 and the bush 2 return to the normal position, the confluence portion x widens and the dynamic pressure on the upper side returns to the original state.

The oil 7 in the groove 11 is
The static pressure is also increased by being fed from 3 toward the stepped portion 14 at the dead end, and as a result, the force of pushing down the shaft 1 acts like the conventional floating bush bearing of FIG. The stability of the shaft 1 is also enhanced by the balance between the static pressures.

Therefore, according to the above-mentioned embodiment, the self-excited vibration caused by the dynamic pressure of the outer oil film 9 can be greatly reduced as compared with the conventional one, and the bearing load is increased by the action of pushing down the shaft 1 by the static pressure. It is also possible to stabilize the shaft 1.

The floating bush bearing of the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

[0022]

According to the floating bush bearing of the present invention described above, the self-excited vibration caused by the dynamic pressure of the outer oil film can be significantly reduced as compared with the conventional one, and the bearing load can be reduced by the action of pushing down the shaft with static pressure. It is possible to obtain an excellent effect that the shaft can be stabilized by increasing the value.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

2 is a development view of the bearing surface of FIG. 1. FIG.

FIG. 3 is a cross-sectional view showing a state in which the shaft and bush of FIG. 1 are close to the groove side.

FIG. 4 is a cross-sectional view showing a conventional example.

5 is a development view of the bearing surface of FIG. 4. FIG.

[Explanation of symbols]

 1 Shaft 4 Bearing Surface 11 Groove 12 Oil Supply Hole 13 Pocket 14 Step

Claims (1)

[Claims] 1. A groove portion extending in an arc shape from the upper part of the bearing surface toward the counter-rotational direction of the shaft at a constant depth is formed, and a pocket communicating with the oil supply hole is formed at a starting end of the groove portion in the rotational direction of the shaft. The floating bush bearing is characterized in that a step portion is formed at each end thereof.