JPH0158768B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a movable journal bearing, and particularly to a dynamic pressure type movable journal bearing.

[Background of the invention]

As a dynamic pressure type movable journal bearing, for example, one shown in US Pat. No. 3,497,276 is known.

The movable journal bearing disclosed in U.S. Pat. No. 3,497,276 is as shown in FIG. Supported without contact. The pad 3a has a fixed pivot 4a,
The pads 3b are supported in point contact with the top of the movable pivot 4b and the bottom 7 of the respective pad groove 6. The fixed pivot 4a is fixed to the bearing housing 8. The movable pivot 4b is supported by an elastic coil spring 10 so as to be movable in the radial direction of the rotary shaft 2 within a hole 9 in the bearing housing 8. One end of the coil spring 10 is restrained by a stroke adjustment screw 12 having a threaded portion that fits into the guide thread groove 11 of the bearing housing 8. The hole 9 has a step 13, and the movable pivot 4b is attached to this step 13.
The structure is such that the movable pivot 4b does not approach the pad 3b side more than a predetermined distance.

When the rotating shaft 2 is stationary, the coil spring 10
The movable pivot 4b pushed toward the rotating shaft 2 by the step 13 of the hole 9 is restrained in the coil spring extension direction.
Top 5 of movable pivot 4b and bottom 7 of pad 3b
is non-contact. That is, the pad 3b has play between the rotating shaft 2 and the movable pivot 4b by the amount of non-contact. This play is to minimize the frictional force on the contact surfaces with the pads 3a and 3b when the rotating shaft 2 starts rotating, so that the rotating shaft 2 can start rotating with a small torque. When the rotating shaft 2 starts rotating, the gas or liquid in the space 14 forms a thin film between the outer surface of the rotating shaft 2 and the surfaces of the three pads 3a and 3b, and the rigidity of the thin film causes the pad 3b to float. As the rotational speed of the rotating shaft 2 increases, the rigidity of the thin film increases, and the flying height of the pad 3b also increases. When the top 5 of the movable pivot 4b contacts the bottom surface 7 of the groove 6 of the pad 3b, the flying height or radial movement distance of the pad 3b is controlled by the stiffness of the coil spring 10. At this time, the stiffness of the thin film matches the stiffness of the coil spring 10. Rotating axis 2
In order to rotate stably at high speeds, the rigidity of the coil spring is set to be relatively stiff so that the rotating shaft is stable at high speeds. That is, if the movable pivot 4b is restrained by the stepped portion 13 and does not stop,
The stiffer rigidity of the coil spring 10 makes the rotating shaft 2 stand still.
The rotating shaft 2 will not begin to rotate unless a large torque is applied directly to it.

Such a movable journal bearing can support the rotating shaft without any problems during steady rotation, but when the rotating shaft is stationary or when the rotating shaft starts rotating,
No countermeasures have been taken for the inconvenience caused by backlash due to non-contact between the top of the movable pivot and the bottom of the pad when the rotation is stopped, that is, during unsteady rotation. That is, during unsteady rotation of the rotating shaft, due to the play, a large collision load is applied between the rotating shaft and the pad due to whirling of the rotating shaft, causing damage to the rotating shaft and the pad. Furthermore, after assembling such a movable journal bearing with a rotating shaft, when transporting this assembly, the rotating shaft is free to move in its radial direction due to the above-mentioned backlash due to the stationary rotating shaft, and the gap between the rotating shaft and the pads is There is a problem in that a collision load is applied to the rotary shaft and pads, causing damage to the rotating shaft and pads.

[Purpose of the invention]

The purpose of the present invention is to eliminate the play between the movable pivot and the pad when the rotating shaft is stationary and during unsteady rotation, thereby preventing collisions between the rotating shaft and the pad when the rotating shaft is stationary and during unsteady rotation. An object of the present invention is to provide a movable journal bearing that can suppress the generation of loads and prevent damage to a rotating shaft and pads.

[Summary of the invention]

The present invention includes: a plurality of pads that support a rotating shaft in the radial direction of the rotating shaft; a movable pivot that supports at least one pad among the pads so that it can move in the radial direction of the rotating shaft; a bearing casing provided with a pivot; a first elastic body that brings the movable pivot into contact with the pad when the rotary shaft is stationary and in unsteady rotation; and a first elastic body that applies a preload to the movable pivot during steady rotation of the rotary shaft. The device is characterized in that it is equipped with a preload loading means having a second elasticity, and is designed to eliminate play between the movable pivot and the pad when the rotating shaft is stationary and during unsteady rotation. be.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIGS. 1 and 2.

In Figure 1, in this case, the movable journal bearing is
A plurality of pads that support the rotating shaft 17 in the radial direction of the rotating shaft 17, a movable pivot 15 that supports at least one pad 16 among the pads so as to be movable in the radial direction of the rotating shaft 17, and the movable pivot 15.
A preload loading means is provided which can change the preload applied to the movable pivot 15 according to the rotational status of the rotating shaft 17, that is, whether the rotating shaft 17 is stationary, unsteady rotation, or steady rotation. It is provided.

In FIG. 1, the preload applying means includes a first elastic body, for example, a coil spring 18a, which brings the movable pivot 15 into contact with the pad 16 to prevent backlash when the rotary shaft 17 is at rest or rotates unsteadily. , a second elastic body, for example, a coil spring 18b, which applies a preload to the movable pivot 15 during steady rotation of the rotating shaft 17. Coil spring 18b
The load required to act on the movable pivot 15 during steady rotation of the rotary shaft 17 is adjusted as shown in FIG.

In FIG. 2, coil spring 18b and coil spring 1
A spring stopper 19, which is a moving body that restrains the spring extension direction at both ends of the spring 8b, and a spring fixing screw 2, which is a restraint body.
0 and a load adjustment screw 22 with a screwdriver groove 21, which is another restraining body that adjusts the preload generated by the coil spring 18b, for example,
A semiconductor type load sensor 27 is attached to a shell 28 installed at the bottom. The load applied to the load sensor 27 is read by a load meter 30 connected with a lead wire 29. When the spring fixing screw 20 is screwed into the shell 28 in the state shown in FIG. 2, the coil spring 18a
The rigidity increases when it is restrained by the spring stopper 19. The load is transmitted to the load sensor 27 in contact with the spring stop 19, and its value is displayed on the load meter 30. In this way, the spring fixing screw 20 is screwed in to a predetermined large load. When a predetermined large load is reached, the load adjustment screw 22
is not in contact with the spring stopper 19, but insert the tip of the screwdriver into the screwdriver groove 21 and remove the spring stopper 1.
In this case, move it upward until it touches 9. After contacting the spring stopper 19, the coil spring 18b
In order to restrict the length of extension, the screw portion 31 is fixed with an adhesive or the like to prevent the screw from loosening. This completes the precise adjustment of the preload generated by the coil spring 18b, and the entire spring fixing screw 20 including the coil spring 18b is removed from the shell 28.

In FIG. 1, after the rotary shaft 17 is assembled with pads such as the pad 16, the movable pivot 15 is inserted into the hole 24 of the bearing housing 23 so that the top thereof is attached to the pad 16.
The pad is inserted into contact with the bottom of the pad groove. Thereafter, the coil spring 18a is inserted into the hole 24 with one end in contact with the movable pivot 15. Thereafter, the spring fixing screw 20 containing the preload-adjusted coil spring 18b is attached to the thread groove 25 of the bearing housing 23, and in this state, the other end of the coil spring 18a is
It comes into contact with the lower end surface of the spring fixing screw 20. after that,
Screw in the spring fixing screw 20 until the rotating shaft 17, pad 16, movable pivot 15, and spring stopper 19 are in contact with each other, and then tighten the screw groove 2
If the screw pitch of No. 5 is 0.5 mm, turn it 1/50 of a turn in the opposite direction, apply 〓 32 between the movable pivot 15 and the spring stopper 19 for about 10 μm, and then tighten the spring fixing screw 20 to the bearing housing 23. Secure with nut 26. Alternatively, the spring fixing screw 20 may be fixed by fixing the threaded portion with an adhesive. In this state, the small preload generated on the coil spring 18a is determined by the spring constant of the coil spring 18a and the distance or stroke between the upper part of the movable pivot 15 and the spring fixing screw 20. Therefore, the coil spring 18a used has a spring constant that can generate a predetermined small preload during the stroke.

A small preload by the coil spring 18a acts to lightly press the pad 16 against the rotating shaft 17. This preload is set to a value that is not so strong as to prevent rotation of the rotating shaft 17 when it starts to rotate. Therefore, in the initial stage of rotation of the rotating shaft 17, that is, in the range from the initial stage of rotation to low speed rotation, stable rotation of the rotating shaft 17 without whirling can be guaranteed by the preload of the coil spring 18a, and the rotating shaft 17 and the pad 16 No collision load occurs between the rotating shafts 1 and 1.
7 rotates steadily like high speed rotation, and pad 16
The flying height of the movable pivot 15 increases, and the movable pivot 15
9, the coil spring 18 is attached to the pad 16.
A large preload b acts additionally, ensuring stable rotation at high speeds. Further, even when the rotation of the rotating shaft 17 is stopped, if the rotational speed decreases, the coil spring 18a supports the pad 16, and stable stopping can be ensured. In addition, even when the rotating shaft 17 is stationary, the coil spring 18a supports the pad 16 without play, so even when transporting the rotating shaft 17 and journal bearing assembly, there is no play between the rotating shaft 17 and the pad 16. No collision loads occur.

According to this embodiment, play between the rotating shaft and the pads can be eliminated from the stationary state of the rotating shaft to the low-speed rotation range. In this case, it is possible to prevent a collision load from being generated between the rotating shaft and the pad, which has the effect of preventing damage to both.

FIG. 3 shows another embodiment of the present invention,
The difference from the embodiment shown in FIG. 1 is that the coil spring 18a is arranged in series with the coil spring 18b,
The spring stop 19 and the movable pivot 15 are in contact with each other when the rotating shaft 17 is in a stationary state.

This embodiment is composed of a spring fixing screw 33 and a coil spring 18a that contacts the upper end of the spring fixing screw 33 and the lower end of the spring support screw 34. The preload produced by coil spring 18b is similarly adjusted as shown in FIG. The preload of the coil spring 18a is determined by adjusting the distance between the spring fixing screw 33 and the spring support screw 34.
7. Set a value that does not prevent rotation at the initial stage of rotation.

When the rotating shaft 17 rotates steadily, the pad 16
floats up, the movable pivot 15 and the coil spring 18
b. The spring fixing screw 33 moves up while contracting the coil spring 18a. A predetermined flying height, that is, the end surface 33a of the spring fixing screw 33 and the spring supporting screw 34
When the distance between the end faces 34a of the coil spring 18b is reached, the two come into contact, and from then on, only the preload of the coil spring 18b acts.

According to this embodiment, when the preload of the coil spring 18b acts, the coil spring 1
Since the preload of 8a is not applied, the coil spring 18
It is only necessary to precisely adjust the preload of the coil spring 18a, and the journal bearing can be assembled without considering the preload of the coil spring 18a.In addition to the effects of the above embodiment, the assembly work can be completed in a short time. There is.

〔Effect of the invention〕

According to the present invention, it is possible to eliminate backlash between the movable pivot and the pad when the rotating shaft is stationary and during unsteady rotation. This has the effect of suppressing the generation of collision loads and preventing damage to the rotating shaft and pad.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view around a movable pivot showing an embodiment of a movable journal bearing according to the present invention, and Fig. 2 shows a coil spring that applies a preload to the movable pivot during steady rotation of the rotating shaft shown in Fig. 1. FIG. 3 is a cross-sectional view showing the preload adjustment situation; FIG. 3 is a cross-sectional view around the movable pivot showing another embodiment of the movable journal bearing according to the present invention; FIG. 4 is a cross-sectional view showing an example of a conventional movable journal bearing. It is a front view. 15...Movable pivot, 16...Pad, 17
... Rotating shaft, 18a, 18b ... Coil spring, 2
3...Bearing housing.

Claims (1)

[Scope of Claims] 1. A plurality of pads that support a rotating shaft in the radial direction of the rotating shaft, and a movable pivot that supports at least one pad among the pads so as to be movable in the radial direction of the rotating shaft. , a bearing casing in which the movable pivot is provided, a first elastic body that brings the movable pivot into contact with the pad when the rotary shaft is stationary or in unsteady rotation, and a preload on the movable pivot when the rotary shaft is in steady rotation. A movable journal bearing comprising: a second elastic body for applying a preload; and a preload applying means having a second elastic body. 2. A coil spring, which is the first elastic body, is inserted into a hole formed in the bearing casing in a radial direction at a position corresponding to the at least one pad, and the movable pivot is inserted into the bearing casing in a manner corresponding to the hole. The coil spring, which is the second elastic body, is stretched between the spring fixing screw to be attached, and the coil spring, which is the second elastic body, is connected to the spring fixing screw and the load adjusting screw provided on the spring fixing screw, and the movable pivot and the coil spring are connected to the spring fixing screw and the load adjusting screw provided on the spring fixing screw. The movable journal bearing according to claim 1, which is stretched between a spring stop that is in contact with and movable in the radial direction. 3. A coil spring, which is the first elastic body, is attached to a spring support screw attached to the bearing casing in a radial direction corresponding to a hole formed in the bearing casing at a position corresponding to the at least one pad. The spring fixing screw is tensioned between the provided spring fixing screw so that it can come into contact with the spring supporting screw during steady rotation of the rotating shaft, and the coil spring that is the second elastic body is connected to the spring fixing screw. The movable journal bearing according to claim 1, wherein the movable journal bearing is tensioned between a load adjusting screw provided on the spring fixing screw and a spring stop that is movable in the radial direction and in contact with the movable pivot.