JPS588825A - Static pressure bearing - Google Patents

Abstract

PURPOSE:To provide a static pressure bearing for conducting a fluid in a high- pressure chamber to the static bearing, and then conducting same to a low- pressure chamber which can lessen the variation of expansion of a bearing gap by making a heat exchange between a part of fluid in the high-pressure chamber and a fluid in the low-pressure chamber to be conducted to a static shaft portion. CONSTITUTION:The interior of an outside casing 11 is partitioned by a bearing casing 5 into a high-pressure chamber 3 and upper and lower-pressure chambers 8, 9. An impeller 2 positioned in the lower low-pressure chamber 9 is fixed on a shaft 16. The shaft 16 is supported by a static pressure bearing 7 comprising a bearing bush 14 fixed on the bearing casing 5 with a circular space 19, and a bearing sleeve 15 fitted close to the shaft 16. A portion of the bearing casing that is exposed to the interior of the high-pressure chamber is covered with a shelter plate 17, and further is coupled thereto by a heat exchanger 18 comprising a supply hole 6' mounted on the casing 5 and a pipe meandering in the circular space 19, which can lessen the variation of a bearing gap 20 caused by thermal expansion and contraction of the bearing casing.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in hydrostatic bearings, and particularly to a hydrostatic bearing in which the amount of stiffening of the bearing gap of the hydrostatic bearing is minimized even if the temperature of a fluid changes rapidly.

Unlike normal ball bearings, hydrostatic bearings have a fixed annular gap between the stationary side and the rotating side (hereinafter referred to as the bearing gap), and pressurized fluid is ejected into this bearing gap. , the shaft is supported by the static pressure of this pressure fluid.

Therefore, in this support structure, the support state changes depending on the pressure of the pressure fluid and the size of the bearing gap.

A conventional hydrostatic bearing has a structure shown in FIG.

That is, the fluid flowing in from the suction port 1 is pressurized by the impeller 2, and most of the fluid passes through the high pressure chamber 3 and enters the discharge port 4.
A part of the liquid is distributed to the static pressure bearing 7 through the supply hole 6 drilled in the bearing casing 5 to lubricate the sliding surfaces, and then divided into an upper low pressure chamber 8 and a lower low pressure chamber 9. It's flowing.

The fluid flowing into the lower low pressure chamber 9 flows through the balance hole 10a.
The fluid that has flowed into the upper low pressure chamber 8 forms a free liquid level within the outer casing 11, is discharged from the overflow pipe 3 through the communication hole 12a, and is discharged from the overflow pipe 3 through the communication hole 12a. Impeller 2 is connected by piping (not shown).
The fish are returned to the suction port 1 of the fish.

To explain the conventional hydrostatic bearing section in more detail in the fiXz diagram, the hydrostatic bearing section 7 is composed of a bearing pusher 14, a bearing sleeve 15 tightly fitted to the shaft 16, and a pusher. A bearing sleeve 15 is inserted into the bush 14 with a bearing gap 2o. The bearing bushing 14 is mounted with an annular space 19 formed between it and the bearing casing 5, and the annular space 19 and the bearing gap 20 allow the inner and outer surfaces of the bearing bushing 14 to come into contact with the fluid. There is.

That is, a portion of the fluid in the high pressure chamber 3 flows directly into the annular space 19 through the supply hole 6 and then into the bearing-r&IU 20 through the bearing supply hole 141.

As a result, if the temperature of the fluid in the high pressure chamber 3 (fluid temperature at the suction port 1) fluctuates rapidly, the inner and outer surfaces are relatively thin and have a small heat capacity, and the inner and outer surfaces are thick walls for fluid flow. Moreover, since it is tightly fitted into the shaft 16 and has a large heat capacity, and only the outer surface is in contact with the fluid, it is difficult to follow changes in the fluid temperature, and the temperature does not change much.

However, the relative thermal expansion and contraction between these two is such that only the bearing bushing 14 is thermally expanding and contracting, and if the fluid temperature rises rapidly, the bearing gap 20 becomes too large. Furthermore, if the fluid temperature suddenly decreases, the bearing gap 20 becomes smaller, making the static pressure support state of the shaft 16 unstable, which may lead to photographing or the like.

In some cases, if the fluid temperature drops too quickly, the bearing clearance becomes zero, causing a phenomenon in which the so-called bearing bush clings to the bearing sleeve, resulting in the bearing seizing.

As described above, conventional hydrostatic bearings have poor reliability against changes in fluid temperature, which may also place restrictions on load fluctuations and other design issues in plants, which may reduce the reliability of the entire plant. This had the disadvantage of lowering the actual value.

The present invention is an attempt to provide a highly reliable hydrostatic bearing that solves the above-mentioned conventional drawbacks.

That is, the present invention does not directly supply the fluid in the high pressure chamber to the bearing gap as in the conventional case, but instead exchanges heat between the fluid m in the high pressure chamber and the fluid staying in the upper low pressure chamber. After alleviating sudden fluctuations in fluid temperature, the fluid is supplied to the bearing gap to reduce the influence of fluid temperature fluctuations on the bearing, while covering the outer surface of the bearing casing exposed in the high pressure chamber. A heat shield plate is provided to alleviate the external influence on sudden changes in fluid temperature, and the bearing clearance is maintained almost constant even if the fluid temperature changes suddenly. do.

The details will be explained below with reference to embodiments shown in the drawings. In FIG. 3, a bearing casing 5 is provided inside the outer casing 11, and the inside of the outer casing 11 is divided into a low pressure chamber and a high pressure chamber 3, and the low pressure chamber is connected to an upper low pressure chamber 8 via a static pressure bearing 7. It is divided into a lower low pressure chamber 9. Reference numeral 14 denotes a bearing bushing, which is attached to the bearing casing 5 with an annular space 19 provided therein.
A hydrostatic bearing 7 is constructed by inserting a bearing sleeve 15 tightly fitted into the bearing sleeve 6 with a bearing gap 20 provided therebetween. An impeller 2 is located in the lower low pressure chamber 9, passes through the upper low pressure chamber 8, and is attached to a shaft 16 supported by a hydrostatic bearing 7. 6°' is a supply hole bored in the bearing casing 5, and is opened so that the high pressure chamber 3 and the upper low pressure chamber 8 communicate with each other. 17 is fever! ! It is a shield plate and is attached with a certain gap so as to cover the outer surface of the bearing casing 5 exposed in the high pressure chamber 3.

In the case of this embodiment, a heat shield plate 17 is attached to a portion corresponding to the upper low pressure chamber 8 and the annular space 19. Reference numeral 18 denotes a heat exchanger, which connects the supply hole 6' and the annular space 19 with a heat transfer tube, and the portion between the supply hole 6' and the annular space 19 is connected to the upper low pressure chamber 8. It is located inside. That is, as shown in FIG. 4 (A-A arrow view in FIG. 3), the heat exchanger 18 is disposed in a planar manner within the upper low pressure chamber 8, and constitutes a necessary heat transfer area.

In the case of this embodiment, the heat exchanger tubes of the heat exchanger 18 are arranged in a planar manner, but they may be arranged three-dimensionally in a zigzag pattern or a grid pattern. However, it is not limited to this. Note that 101 is a balance hole, 10 is an impeller shroud, and 14a is a bearing supply hole.

In the embodiment of the present application configured as above, the operation will be explained next. First, the impeller 2 rotates together with the shaft 16 at a rotational speed that depends on the required fluid flow rate or pressure. The fluid sucked in from the suction port 1 (FIG. 1) by the impeller 2 is pressurized and flows out into the high pressure chamber 3. A portion of the fluid thus pressurized and flowing out into the high pressure chamber 3 flows through the supply hole 6', is guided into the annular space 19, and is forced into the bearing gap 20 through the bearing supply hole 14m. The fluid pumped in this way collides with the wall surface of the bearing sleeve 15 and is divided into upper and lower directions within the bearing gap 20. The fluid thus diverted upward is stored in the outer casing 11, forms a free liquid level, and remains there while flowing out from the overflow pipe 13 (FIG. 1). The fluid thus retained in the outer casing 11 becomes a swirling flow due to the rotation of the shaft 16. Further, fluid remains in the gap between the heat shield plate 17 and the bearing casing 5, forming a kind of heat insulating layer.

Now, when the fluid temperature changes suddenly, the supply hole 6
The fluid flowing into the heat exchanger 18 from ' is turned into a swirling flow and exchanges heat with the fluid staying in the outer casing 11 . For example, when the fluid a degree suddenly rises, it is cooled by the fluid staying in the outer casing 11, and when it suddenly becomes low temperature, it is heated, the sudden temperature change is alleviated, and the annular space 19.

During the heat exchange, the fluid retained in the outer casing 11 is swirling, so it flows outside the heat transfer tubes forming the heat exchanger 18 at a speed commensurate with the rotational speed of the shaft 160. Yes, the heat transfer coefficient improves accordingly. On the other hand, in the high pressure chamber 3, heat conduction to the bearing casing 5 is relaxed by the heat shielding plate 17 and the heat insulating layer of the staying fluid.

As detailed above, according to the present invention, after a part of the fluid in the high pressure chamber is heat exchanged with the fluid staying in the upper low pressure chamber,
Since the fluid is supplied to the bearing gap, even if the temperature of the sucked fluid fluctuates rapidly, the temperature change of the fluid supplied to the bearing gap is alleviated by the above heat exchange, and furthermore, even if the temperature of the fluid sucked in changes rapidly, the temperature change of the fluid supplied to the bearing gap is alleviated. A heat shield plate is provided to cover the outer surface of the bearing casing, so even if the temperature of the sucked fluid fluctuates rapidly, heat transfer to the bearing casing is suppressed.
Sudden temperature changes in the bearing casing are alleviated, and the synergistic effect of these two makes it possible to keep the thermal expansion and contraction of the bearing bushings small and keep the bearing clearance almost constant, resulting in highly reliable hydrostatic bearings. This has significant effects, such as simultaneously improving the reliability of the entire plant and eliminating design constraints.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of a liquid metal pump as a representative example of a conventional example that uses a hydrostatic bearing, and Figure 2 is an enlarged cross-sectional view of only the conventional hydrostatic bearing part. FIG. 3 is an enlarged view of a hydrostatic bearing portion in an embodiment of the present invention, and FIG. 4 is a view taken along the line A--A in FIG. 3. 3... High pressure chamber, 5... Bearing casing, 6.6'.
... Supply hole, 7... Static pressure bearing, End... Upper low pressure chamber, 9
...Lower low pressure chamber, 11...Outer casing, 14...
・Bearing bushing, 15...Bearing sleeve, 16...
Shaft, 17... Heat shielding plate, 18... Heat exchanger, 19.
...Annular space, 20...Bearing clearance. Figure 1 Figure 2/

Claims (1)

[Claims] A bearing casing is provided inside the outer casing, the inside of the outer casing is divided into a high pressure chamber and a low pressure chamber, and the low pressure is further divided into an upper low pressure chamber and a lower low pressure chamber via a static pressure bearing, and one part of the high pressure chamber is divided into an upper low pressure chamber and a lower low pressure chamber. After exchanging heat with the fluid retained in the upper low-pressure chamber, the fluid is guided to the static pressure bearing section, while a heat exchanger plate is installed to cover the outer surface of the bearing casing exposed in the high-pressure chamber. installation, even if the fluid temperature fluctuates rapidly.
A hydrostatic bearing characterized in that the amount of change in a hydrostatic bearing gap due to a change in the amount of thermal expansion of a bearing portion is reduced.