JPH04203519A - Thrust slide bearing for rotary body and screw compressor - Google Patents

Abstract

PURPOSE:To prevent the seizure of the inner peripheral side by the thrust load deformation by forming each projection on the inner and outer peripheral sides on the back surface of one flat plate of a thrust slide bearing constituted of two flat plates and forming the outer peripheral side projection higher than the inner peripheral side projection. CONSTITUTION:A runner 1 as revolution side disc is fixed on the installation stage part 3a of a rotary shaft 3 by a nut 2, and arranged oppositely to a metal 4 as static side flat plate. The nut 2 has the larger diameter than the inside diameter of the metal 4, and has the inner and outer peripheral side projections 2a and 2b in each circumferential form, and the height of the outer peripheral side projection 2b is larger than the inner peripheral side projection 2a. When the nut 2 is tightened on a rotary shaft 3, the outer peripheral side projection 2b contacts the runner 1, and when the nut 2 is tightened furthermore, the nut 2 is warped downward, and the runner 1 deforms upwardly. Finally, the inner peripheral side projection 2a contacts the runner 1, and is tightened with a prescribed torque. In the assembled state, the outer peripheral part of the runner 1 protrudes from the center part, and develops a recessed surface form. The runner 1 restores the flat surface, receiving a thrust load, and the nut 2 develops the action of a spring and cushion.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thrust slide bearing for a rotating body and a screw compressor.

[Conventional technology]

This thrust sliding bearing is composed of two circular parallel flat plates, and has the advantages of being inexpensive and having a simple structure. However, when the load is large and the surface pressure is high, or when the oil temperature is high,
If the viscosity of the lubricating liquid, such as water or mixed refrigerant oil, is low, the thickness of the oil film (water belly) formed on the sliding bearing surface is insufficient, causing fixed contact between the stationary body and the rotating body, leading to seizure. . For such applications, low-viscosity liquid lubrication equipment was developed by machining shallow spiral grooves (spiral groups) on one circular plate to generate dynamic pressure in the lubricant due to rotation to support thrust force. , for example, a submersible pump (JP-A-60-26814
The dynamic pressure effect is remarkable and can increase the seizure limit of circular parallel plate type thrust slide bearings.

However, in order to further increase the seizure limit, it is important to achieve one-surface accuracy, that is, to reduce surface roughness and waviness to prevent uneven contact. Surface roughness and waviness can be improved by careful processing and finishing.

One way to prevent uneven contact is to provide one circular parallel plate with an alignment mechanism to absorb errors in the inclination, or perpendicularity, between the shaft and the rotating flat plate with respect to the stationary flat plate (for example, Japanese Patent Application Laid-Open No. 1983-1999) 26814) is also disclosed.

In addition to the inclination caused by the above-mentioned squareness error, uneven contact occurs on the inner peripheral side of the circular parallel flat plate. This is because when a circular parallel plate supports a load, it deforms into a slightly convex shape. When this phenomenon occurs, solid contact with the other surface is likely to occur on the inner circumferential side, which has a low load-bearing capacity, and is the main cause of lowering the load capacity. . In order to avoid this phenomenon, the inventor of the present application first developed a thrust sliding system in which the rotating side flat plate (hereinafter referred to as runner) is supported from the back side to the rotating shaft on the outer circumferential side of the stationary side flat plate (hereinafter referred to as metal) than the inner diameter. Proposed a method for fixing bearings (Japanese Patent Application Laid-Open No. 1999-1500)
(Refer to Publication No. 13), this effect is remarkable, and seizure on the inner peripheral side can be prevented and the load capacity can be increased.

Figure 10 is a longitudinal cross-sectional view of the proposed thrust plain bearing.
1 is a runner, 2 is a rotating shaft, and 3 is a tightening tool (hereinafter referred to as a nut).

[Problem to be solved by the invention]

The technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 1-150013 is effective in preventing uneven contact on the inner circumferential side, but since the concave deformation of the runner against the metal is too large, it becomes circular during long-term operation. There was a drawback that the outer peripheral side of the parallel plate was worn out. Furthermore, in some cases, uneven contact on the outer circumferential side may lead to seizure.

The runner is fixed to the rotating shaft with a nut, but there is a protrusion on the outer circumference of the nut, and because the protrusion presses the runner from behind, the runner deforms into a concave shape.

The tightening of the nut to fix the runner to the rotating shaft is determined by the torque, and the amount of deformation also increases or decreases depending on the tightening torque.

Therefore, if the launch is securely fixed to the rotating shaft, the amount of deformation will be excessive and the above-mentioned problems will occur.

Furthermore, although the above-mentioned method for preventing uneven contact on the inner peripheral side has increased the seizure resistance limit, the load capacity is insufficient when the lubrication conditions are poor and the supporting load is excessive.

The purpose of the present invention is to alleviate excessive concave deformation of the runner and prevent wear on the outer circumferential side of the circular parallel flat plate, and another purpose of the present invention is to increase the load capacity of the thrust periphery bearing. .

[Means to solve the problem]

The configuration of the present invention adopted to solve the above-mentioned problems is as follows: (1) In a thrust sliding bearing for a rotating body, in a thrust peri-bearing composed of two opposing flat plates, the two plates A load support plate made of a flat plate and elastically supporting the load is provided on the back of one of the flat plates,
The load supporting plate has protrusions on the inner circumferential side and the 9+ circumferential side, and the protrusion on the outer circumferential side is higher than the protrusion on the inner circumferential side, and in (2) and (1), In (3), (1) or (2), a plurality of through holes are provided between the inner circumferential side and the outer circumferential side protrusion of the load support plate, and in (3), (1) or (2), one of the flat plates A spiral group is provided from the inner circumference to the outer circumference, and in (4), (1), (2), or (3), high-pressure lubricating fluid is provided on the inner circumference side of the two flat plates. A screw compressor is characterized in that: (5) a male and female rotor that engages with each other is housed in a casing, and the male and female rotors are arranged such that a radial force is received by a radial bearing provided in the casing; A screw compression screw supporting the rotor shaft of the rotor and receiving axial force by a thrust sliding bearing consisting of a stationary side flat plate provided on the casing and a rotating side flat plate provided at the shaft ends of the male and female rotors. In the machine, the flat plate on the rotating side has a spiral group extending from the inner periphery to the outer periphery, and a load supporting plate made of a flat plate and elastically supporting a load is provided on the back side of the rotating side flat plate, and the load supporting plate The plate has protrusions on the inner circumferential side and the outer circumferential side, and the protrusion on the outer circumferential side is higher than the protrusion on the inner circumferential side, and in (6) and (5), the stationary side flat plate and The present invention is characterized in that a high-pressure lubricating fluid is pumped to the rotating flat plate.

In other words, is the back side of one flat plate equivalent to the flat plate of the bearing material?
The thin flat plate-shaped fastener is supported and fixed by a tool, and the fastener has protrusions on the inner and outer circumferential sides of the surface that contacts the flat plate of the bearing material of the tool, and the protrusions on the outer circumference are higher than the inner circumference. It is.

Furthermore, in order to achieve the above-mentioned other objects, a spiral group extending from the inner periphery to the outer periphery is provided on the bearing material flat plate on the negative side.

Furthermore, in order to increase the load capacity, high-pressure lubricating fluid is pumped to the inner peripheral side of the two flat plates of the bearing.

[Effect]

One circular parallel plate (runner) is tightened like a flat plate on the back! The tightening is fixed to the rotating shaft with (nut). The nut is larger in size than the inner diameter of the other flat plate (metal) of the bearing material, and has protrusions on the inner and outer circumferential sides, with the protrusions on the outer circumferential side being higher than the inner circumferential side.

Therefore, the nut first contacts the runner from the outer circumferential side, and the runner and nut deform (warp) each other, and finally the protrusion on the inner circumferential side comes into contact with the runner. Since the nut is tightened to the rotating shaft with a specified torque, the runner is securely fixed to the rotating shaft.

Furthermore, the deformation of the runner relative to the metal is determined by the step difference between the protrusions on the outer circumferential side and the protrusions on the inner circumferential side of the nut, so that the metal does not deform excessively.

Furthermore, the spiral group provided on the runner toward the outer periphery creates an oil film pressure distribution that gradually increases from the inner periphery to the outer periphery, and a large oil film pressure is obtained on the outer periphery side where the area is larger, thereby increasing the load capacity.

〔Example〕

Examples will be described below.

FIG. 1 is a vertical cross-sectional view of one embodiment of the thrust slide bearing of the present invention, in which 1 is a runner which is a rotating side disc, and the rotating shaft 3 is fixed to the stepped portion 3a by tightening the nut (2). ,
It is arranged opposite to the metal 4 which is a stationary side flat plate.

Nut 2 has a larger diameter (758 mm) than the inner diameter (40 m) of metal 4.
), and has an inner circumferential protrusion 2a and an outer circumferential protrusion 2b.

The inner protrusion 2a and the outer protrusion 2b have a circular shape, and the height of the outer protrusion 2b is 50 μm (+
10 μm) high (see Figure 2). The thickness of nut 2 is 7n
, the runner thickness is 101 m.

When the nut 2 is tightened onto the rotating shaft 3, the outer peripheral protrusion 2b first comes into contact with the runner 1. When tightened further, the nut 2 warps downward in the figure, and the launch 1 deforms to the opposite side, that is, upward (see Figure 3).Finally, the inner protrusion 2a
is in contact with runner L, and the specified torque is 1500 kg-m.
(See Figure 1).

When assembled in this manner, the outer peripheral portion of the runner 1 has a concave shape extending approximately 20 μm (+5 μm) from the central portion. That is, the runner 1 is elastically deformed by the nut 2 and attached to the rotating shaft 3. It is important to maintain both the runner 1 and the nut 2 within their elastic deformation limits. On the other hand, in the conventional example, when the runner was tightened with a torque of 1500 kg-m to securely fix the runner to the rotating shaft, the runner was deformed into a concave shape too much, resulting in plastic deformation.

The lubricating fluid is oil, and is supplied from around the rotating shaft 3 to the inner peripheral side of the runner 1 and metal 4. At this time, the higher the oil supply pressure, the more the lubricating oil acts as static pressure, increasing the load capacity.

Further, a groove (spiral group) 1a shown in FIG. 4 is provided on the surface of the runner 1 (the surface facing the metal 4). This groove 1a has a depth of 30 μm, extends from the inner circumference to the outer circumference, and stops at a position seven disks smaller in radius than the outer diameter of the runner I.

In order to investigate the effect of the nut 2, an element test was conducted in which the rotating shaft 3 was driven with 60 balls and the thrust load was gradually increased.
In this example, the nut withstood more than twice as much thrust load as a normal flat nut.

Furthermore, it was applied to a screw compressor and its load bearing capacity was investigated. FIG. 5 shows an embodiment of the screw compressor of the present invention using the thrust periphery bearing shown in FIG. 12, female rotor 1
3 is rotatably housed in radial bearings 12a, 13a, 12b, 13b and thrust sliding bearings 12t, 13t. At one end of the male rotor 12 is an electric motor rotor (
(not shown) is installed, and the female rotor 13 is driven by the male rotor 12.

Low-pressure, low-temperature refrigerant gas is introduced from the left side in the figure into a space composed of two rotors, that is, the male rotor 12, the female rotor 13, and the main casing 11, and the male rotor 12,
As the female rotor 13 rotates, the closed space is gradually reduced and compressed. The refrigerant gas compressed to high pressure and high temperature is led to the discharge chamber and goes out to the air conditioning or refrigeration cycle unit, and the refrigerant gas returned at low pressure and low temperature is compressed and repeated as described above.

An oil supply hole 11a provided in the casing 11 is provided to each bearing.
Lubricating oil is sent through. Lubricating oil is retained in a portion of the discharge chamber and is pumped to each bearing under high discharge pressure. One end of each bearing communicates with the suction, where it is compressed together with low-pressure refrigerant gas, separated from the refrigerant gas in a discharge chamber, and subsequently circulated. In the process of being compressed together with the refrigerant gas, the male rotor 12, female rotor 13 and casing 11
It also takes charge of the sealing action between the male rotor 12 and the female rotor 13, and the lubricating action of the meshing portion between the male rotor 12 and the female rotor 13. The lubricating oil supplied to the thrust sliding bearing is also 10kg/dG to 28kg/al!
It is pumped at a high discharge pressure of G, and static pressure acts to increase the load capacity. The runner 1 is provided with a spiral group as shown in FIG.

Metal 4 of male rotor 12 in actual working condition of screw compressor
The oil film pressure was actually measured. In addition to the thrust sliding bearing according to the present invention, for comparison purposes, measurements were also taken on a runner provided with grooves of the inflow radial group shown in FIG. 6, and a thrust periphery bearing fixed with a normal nut. 7th
The figure shows the results of the measurements, and Comparison A is the 4th measurement result.
The specimen shown in the figure is a specimen in which the runner is fixed with a conventional nut, and Comparison B is a specimen in which the launch shown in FIG. 6 is secured with a nut of the present invention. FIG. 7 shows that in the thrust periphery bearing of the present invention, the oil film pressure increases from the supply oil pressure toward the outer diameter of the bearing, and after reaching the highest pressure at the end of the spiral group 1a,
On the other hand, in Comparison A, the oil film pressure decreased partially at the inner circumference of the bearing from the supply oil pressure, and increased at the outer side, particularly from the center of the bearing surface to the outer circumference. This is because the runner warps under load, which restricts the flow of lubricating oil at the inner periphery. Even if the oil film pressure increases rapidly on the outer periphery, the launch will continue to warp, so the inner periphery will seize under a light load.

In Comparison B, the pressure decreases from the center to the outer periphery of the bearing surface, and oil film formation is poor, so the metal temperature is about 20 deg higher than the other two sides. However, it can support a higher load than comparison A.

Figure 8 shows the results of a comparison of load resistance and heat resistance. The horizontal axis shows the bearing surface pressure at the support limit W, and the vertical axis shows the oil supply temperature at which lubrication is possible. The thrust sliding bearing according to the present invention has high load-bearing limit and high heat resistance, and covers all operating ranges of screw compressors.

Comparison B showed the second highest performance, although the bearing metal temperature was high. Comparison A is considerably inferior to comparison B. Comparison C is a case where the runner shown in FIG. 7 is fixed with a normal nut, and the load resistance is extremely low. From these results, we can conclude that the lunch deformation (
It can be seen that the effect of the present invention is significant because the warpage (curvature) impairs the load resistance.

Theoretically, the inflow type, which increases pressure from the outer circumference to the inner circumference, has a higher load capacity than the spiral group that goes from the inner circumference to the outer circumference (outflow type), and the inflow type is often used for boat fishing. has been done.

However, in the inflow type, the lubricating fluid tends to scatter from the starting point of the group due to the centrifugal force of rotation, causing oil to run out.The reason why the pressure at the outer periphery is low in Comparison B, indicated by the broken line in Figure 7, is due to oil running out. It is estimated that

By the way, in a screw compressor, the rotor bends due to the reaction force of high-pressure gas. As shown in Figure 9, if you take the rotor in cross section and look at the motor side from the thrust sliding bearing, you will see that a radial load acts in the direction of the arrow in the figure. , the rotor deflects between the two radial bearings. The deflection of the rotor also affects the thrust sliding bearing, and the uneven contact is strong in the left part of the metal in the male rotor 12 and in the upper right part in the female rotor 13.
This problem can be solved using the above-mentioned mechanism (see Japanese Patent Laid-Open No. 60-26814), but the structure is complex and the reliability of the III heart mechanism itself is an important issue to consider.

In contrast, the present invention has the ability to effectively absorb uneven contact due to deflection. In other words, the concave deformation of the runner l occurs because it is pushed by the nut 2 on the back, but when a thrust load is applied, the runner l returns to its original state. trying to return to a flat surface. The oaks 1 to 2 support the reaction force and thrust load of 1 / 1, and the larger the thrust load, the closer the surface becomes to a flat surface. That is, the nut 2 exhibits the action of a spring or a cushion.

In order to exert this spring action, the stress in the runner I and the nut 2 must be within the elastic deformation limit, and
In order to maintain the rigidity of the spring at an appropriate level, it is necessary to increase the distance between the supporting point on the inner circumferential side of the nut 2 and the supporting point on the outer circumferential side. Because of this, in order to keep the runner and nut within the elastic limit,
The height of the protrusion must be made low, and in this case, as shown in FIG.
It approaches the support point, making it impossible to obtain appropriate rigidity, and poor followability against uneven contact due to squareness errors.

It is particularly suitable for equipment that is subject to high surface pressure or is lubricated with a low-viscosity fluid, making it difficult to form a liquid film on the bearing surface, such as refrigeration and air conditioning compressors, especially screw compressors, and submersible pumps. It can be used for.

〔Effect of the invention〕

According to the present invention, the runner or metal of the thrust sliding bearing can be elastically supported from the back side and deformed in advance, so that it is possible to prevent the inner peripheral side from seizing due to thrust load deformation. In addition, since uneven contact due to shaft deflection can be alleviated, seizure resistance can be improved, which is a great industrial effect.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of the thrust 1 to sliding bearing according to an embodiment of the present invention, Fig. 2 is a longitudinal cross-sectional view of the main parts of Fig. 1, and Fig. 3 is an explanatory diagram showing the operating state of the main parts. , FIG. 4 is a plan view of the main parts of another embodiment, FIG. 5 is a longitudinal cross-sectional view of an embodiment of the screw compressor of the present invention, and FIG. Fig. 7 is an explanatory diagram of the oil film pressure measurement results, Fig. 8 is an explanatory diagram of the bearing performance comparison test results,
FIG. 9 is a partial vertical cross-sectional view of the main part of FIG. 5, and FIG. 10 is a vertical cross-sectional view of a conventional slither bearing. 1... Rotating side disc runner), 2... Tightening tool (nut), 3... Rotating shaft, 4... Stationary side flat plate (metal) (
(and 1 other person) Figure 1 Figure 2 Protrusion, 3... Rotating shaft, 4 Stationary side flat plate Figure 3 Figure 4 1... Rotating side disc, 1a... Spiral group Figure 5 Figure 6 Figure 7 Radius r (chicken) Figure 8 Bearing surface pressure Figure 9 Figure 10 / Z b

Claims (1)

[Claims] 1. In a thrust sliding bearing composed of two flat plates facing each other, a load support plate made of a flat plate and elastically supporting the load is provided on the back surface of one of the two flat plates. A thrust sliding bearing for a rotating body, wherein the load support plate has protrusions on an inner circumferential side and an outer circumferential side, and the protrusions on the outer circumferential side are higher than the protrusions on the inner circumferential side. 2. A plurality of through holes are provided between the protrusions on the inner peripheral side and the outer peripheral side of the load support plate, Claim 1
Thrust sliding bearings for rotating bodies as described in section. 3. Claim 1 or 2, wherein one of the flat plates is provided with a spiral group extending from the inner circumference to the outer circumference.
Thrust sliding bearing for the rotating body described. 4. The thrust sliding bearing for a rotating body according to claim 1, 2, or 3, wherein a high-pressure lubricating fluid is pumped to the inner circumferential side of the two flat plates. 5. A stationary side flat plate that houses male and female rotors that mesh with each other in a casing, supports rotor shafts of the male and female rotors so as to receive radial force by radial sliding bearings that are provided in the casing, and that is provided in the casing. In a screw compressor configured to receive axial force by a thrust sliding bearing consisting of a rotating flat plate provided at the shaft end of the male and female rotors, the rotating flat plate is a spiral group directed from an inner circumference to an outer circumference. A load supporting plate made of a flat plate and elastically supporting a load is provided on the back surface of the rotation side flat plate, and the load supporting plate has protrusions on the inner circumferential side and the outer circumferential side. A screw compressor characterized in that the protrusion is higher than the protrusion on the inner peripheral side. 6. The screw compressor according to claim 5, wherein a high-pressure lubricating fluid is pumped to the stationary flat plate and the rotating flat plate.