JPS609459Y2 - Inclined pad type gas bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inclined pad type gas bearing used at high speeds.

Inclined pad type gas bearings are used in bearings for turbomachines such as blowers, gas circulation machines, gas compressors, superchargers, and expanders.

To explain a conventional inclined pad type gas bearing with reference to FIG. 1, a pad C arranged around an axis a is connected to a pivot seat e having a spherical tip fixed to a bearing housing b via a pivot seat d. The pad C is supported by the rotation of the axis a, and the pad C is tilted in the axis rotation direction around the pivot e.
Loading capacity is generated by the dynamic pressure effect of the gas film.

However, since the contact surfaces of the pivot e and the pivot seat d swing under high surface pressure, a highly hard material is used for both to prevent fretting, and the spherical surface and spherical seat are made with high precision. It had to be processed.

Therefore, the inclined pad type gas bearing has the following problems.

■ Because the pad has a pivot seat, it is thick and heavy, and requires a large storage space.

■ Because the pad is heavy, it is not possible to increase the pad's natural frequency, which causes pad vibration at high speeds, which becomes an obstacle to increasing speed.

■ Manufacturing costs are high because the structure is complex and requires high-precision machining.

The present invention was developed with the aim of providing an inclined pad type gas bearing that is stable in high-speed ranges, has low manufacturing costs, and can be mass-produced. Both ends of a supporting leaf spring curved to a required curvature are fixed to a required position on the outer circumference in the circumferential direction, and an auxiliary leaf spring curved to a required curvature is provided in the space between the supporting leaf spring and the pad. The top of the outer periphery of the auxiliary leaf spring is brought into contact with the top of the inner periphery of the support leaf spring, and both ends of the auxiliary leaf spring are brought into contact with predetermined positions in the circumferential direction of the outer periphery of the pad to form a pad unit. A plurality of the pad units are disposed at required intervals around the shaft passing through the bearing housing, and the pad unit is attached to the top of the bearing housing where the supporting leaf spring contacts the nozzing. This invention relates to an inclined pad type gas bearing characterized in that it is engaged so as to be able to swing in the direction of shaft rotation.

Hereinafter, embodiments of the present invention will be described based on the drawings.

First, the structure of the pad unit 6 will be explained with reference to FIG.

Both ends of a supporting leaf spring 4 made of a thin steel plate, which is curved to have a desired curvature, are fixed to the outer circumferential surface of the arc-shaped pad 3 having a desired curvature, for example, by pivot welding. An auxiliary leaf spring 5 made of a thin steel plate that is curved to have a required curvature is arranged between the leaf spring 4 and the pad 3,
The top of the outer periphery of the auxiliary leaf spring 5 is brought into contact with the top of the inner periphery of the support leaf spring 4, and both ends of the auxiliary leaf spring 5 are brought into contact with predetermined positions on the outer periphery of both ends of the back surface of the pad 3; A pad unit 6 is configured.

In the free state where the supporting leaf spring 4 and the auxiliary leaf spring 5 are simply attached to the pad 3, the height from the top of the outer peripheral surface of the pad 3 to the outer peripheral top of the supporting leaf spring 4 is less than or equal to, as shown in FIG.
This is called the curved height.

) The radius of curvature of the curved portion of the supporting leaf spring 4 is r.

The distance between both ends of the auxiliary leaf spring 5, that is, the span is 1°.

The state in which the pad unit 6 is attached to the bearing housing 2 will be explained with reference to FIGS. 3 and 4. A plurality of the pad units (in this embodiment, a plurality of pad units (in this embodiment, a plurality of pad units) are installed at required positions on the inner circumference of the bearing housing 2 at approximately equal intervals. 4) are arranged as shown in Figure 4, and the contact portions of the supporting leaf springs 4 and the auxiliary leaf springs 5 of the pad unit 6 are brought into contact with the inner circumferential surface of the bearing housing 2, and the corresponding contact portions are brought into contact with the inner peripheral surface of the bearing housing 2. The rotation stop pin 7 locks the pad unit 6 so that it can swing in the circumferential direction.

When the shaft 1 is passed through the bearing housing in which the pad unit is locked, and the outer circumferential surface of the shaft 1 is surrounded by the inner circumferential surface of the pad 3, the support plate spring 4 of the pad unit 6 is When a load is applied, the height of the curved portion of the supporting leaf spring 4 becomes t1, the radius of curvature becomes r, and the span of the auxiliary leaf spring 5 becomes 1.

Further, if the radius of the shaft 1 is R1 and the radius of the inner peripheral surface of the pad 3 is rp, then rp>R.

Fig. 4 shows an example in which four pad units are arranged in the inclined pad type gas bearing of the present invention, but any number of pad units may be used, and it is preferable to arrange three or more pad units as much as possible. It is preferable.

Next, the operation of the present invention will be explained.

When the shaft 1 is in a stopped state, the center of the circular arc on the inner circumference of the pad 3 is in contact with the outer circumference of the shaft 1, but when it starts rotating, the pad 3 touches the fulcrum 8 of the rotation stopper pin 7, as shown in FIG. A wedge-shaped gap is formed between the shaft 1 and the pad 3, and as the rotational speed increases, the dynamic pressure effect of the gas film occurs, and the shaft 1 is tilted toward the rotation direction of the pad 3. It rises from 3.

At the rotational speed ω, the pad 3 is tilted by a small angle θ, and the minimum gap between the shaft 1 and the pad 3, that is, the minimum glass film thickness is hmin.

At this time, the support plate spring 4 receives a force due to the pressure of the gas film generated by the dynamic pressure effect, and the height of the curved portion thereof decreases from t when it is at rest to tl.

In addition, the span of the auxiliary leaf spring 5 increases from 1 to 1□,
Frictional force acts on the contact surface between the auxiliary leaf spring 5 and the pad 3, and the pad exhibits a damping effect.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but includes increasing the surface hardness of the shaft in order to avoid excessive wear and damage to the sliding surface due to contact between the shaft and the pad during startup; Of course, various changes may be made without departing from the gist of the present invention, such as adhering a thin film of Teflon or the like to the sliding surface of the pad to reduce the coefficient of friction.

Since the inclined pad type gas bearing of the present invention has the above-mentioned configuration, ■ By attaching a curved leaf spring to the back of the pad, the function of the inclined pad type bearing can be achieved without using a pivot support mechanism. comes out.

■ Since no pivot support mechanism is required, the structure is simple and the weight of the pad can be reduced.

Therefore, the natural frequency of the vibration system made up of the spring characteristics of the pad and the gas film can be increased, and the speed of the turbomachine can be further increased than in the past.

■ Since no pivot support mechanism is required, the structure is simple and high-precision machining of parts other than the sliding surface of the pad is not required, making mass production possible and significantly reducing manufacturing costs.

■ The preload of the bearing can be easily changed by combining the supporting leaf spring and the auxiliary leaf spring.

■ The auxiliary leaf spring provides a damping effect on the pad.

etc., exhibits various excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a conventional inclined pad type gas bearing, FIG. 2 is a structural explanatory diagram of a pad unit 6 constituting the inclined pad type gas bearing of the present invention, and FIG. 3 is a plan view of the pad unit 6 shown in FIG. Explanatory diagram of the state in which the is installed in the bearing housing, No. 4
The figure shows the overall view of the inclined pad type gas bearing of the present invention and the fifth
The figure is an explanatory view showing the operating state of the inclined pad type gas bearing of the present invention. 1 is a shaft, 2 is a bearing housing, 3 is a pad, 4 is a supporting leaf spring, 5 is an auxiliary leaf spring, 6 is a pad unit, and 7 is a rotation stopper pin.

Claims (1)

[Scope of utility model registration request] Both ends of a support plate spring curved to a desired curvature are fixed to a predetermined position on the circumferential outer circumference of an arc-shaped pad having a predetermined curvature, and the support leaf spring is fixed to a space between the support plate spring and the pad. An auxiliary leaf spring curved to a required curvature is arranged, and the top of the outer periphery of the auxiliary leaf spring is brought into contact with the top of the inner periphery of the support leaf spring, and both ends of the auxiliary leaf spring are connected to the circumference of the outer periphery of the pad. A plurality of pad units are arranged at required intervals around a shaft passing through the bearing housing, and the supporting leaf spring is connected to the bearing housing in contact with the bearing housing at a desired position to form a pad unit. 1. A tilted pad type gas bearing, characterized in that a contacting top portion is locked so that the pad can swing in the direction of shaft rotation.