JPH09228971A - Oil supply device of scroll fluid machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress foaming of refrigerant dissolved due to the reduction of pressure so as to prevent the wear and burning of a bearing by forming an oil supply groove in such a manner that its cross sectional area is increased toward the direction of flow of lubricant in a scroll fluid machine which forms the oil supply groove in the axial direction. on a surface of a shaft and performs lubrication between the shaft and the bearing. SOLUTION: In a scroll fluid machine, an oil supply hole 18 is formed in a crank shaft 9, and oil in a bottom part of a chamber raises the oil supply hole 18 based on a difference between pressure in an oil collection part and pressure in a back pressure chamber 19 to supply oil into each part. That is, oil to be supplied into a bearing 8 is introduced into an oil chamber 20 formed by a crank part 9b, a slide bearing 8, and a wall face of a turn scroll, then flows into an oil supply groove 21, and is supplied to a rotary slide part of the slide bearing 8 and the crank part 9b. At this time, it is possible to prevent the generation of gas in accordance with the expansion of volume generated by the reduction of supply oil pressure by forming a cross sectional area of the oil supply groove 21 in such a manner that it is increased gradually toward the direction of flow of supply oil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing oil supply structure for a scroll fluid machine used in a compressor, an expander, a fluid pump, etc., and particularly, it is expected that gas, bubbles, etc. will be generated due to pressure reduction in the bearing. The present invention relates to an oil supply device capable of ensuring a stable bearing oil film thickness even with such an oil supply device.

[0002]

2. Description of the Related Art In a conventional apparatus, as described in Japanese Patent Laid-Open No. 57-76201, an oil supply groove for oiling a bearing of a scroll compressor is provided in parallel with a shaft. The refrigerant gas is melted in, and when an oil supply mechanism for supplying oil by a differential pressure is used, there is a possibility that the refrigerant (gas) foams due to the pressure reduction when the oil passes through the bearing. Also,
Since the oil after refueling the orbiting scroll bearing and the bearing of the frame portion is released to the depressurized room, the clogging of the shaft is likely to occur due to the cooling of the refrigerant (gas) in the opening portion.

Also, regarding the oil supply groove described in Japanese Patent Laid-Open No. 63-29083, the optimum oil supply groove position with respect to the load position is not provided. However, similar to the above, foaming of the refrigerant dissolved in the oil Was not disclosed.

On the other hand, in this technical field, there is a shift from the HCFC refrigerant system to the use of chlorine-free HFC refrigerants due to global environmental problems. That is, conventionally, in addition to the lubrication function of the lubricating oil, chlorine contained in the refrigerant serves as an extreme pressure agent for lubrication and shows good lubrication, but HF containing no chlorine is used.
In C type, we cannot expect the lubrication characteristics of the refrigerant itself,
It is becoming more and more difficult for bearings to secure reliability.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention prevents the refrigerant from foaming in the bearing in the oil supplied to the bearing of the scroll compressor and ensures a sufficient oil film thickness. Provide a refueling structure that can be secured.

[0006]

The above-mentioned object can be achieved by arranging the cross-sectional area of the oil supply groove provided on the surface of the crankshaft to be gradually larger in the oil supply flow direction.

Further, in the case of a bearing structure including a plurality of bearings, in which the second bearing is lubricated after the first bearing is lubricated, the second lubrication groove cross-sectional area is larger than the first lubrication groove cross-sectional area. By installing the gas, it is possible to prevent the generation of gas due to the volume expansion caused by the decrease in the hydraulic pressure, and the gas is not caught in the bearing load surface.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In this embodiment, an example in which a scroll fluid machine is used as a compressor will be described.

1 and 2 show an example of a scroll fluid machine. In FIG. 1, 1 is a chamber, 2 is a fixed scroll, and 3 is an orbiting scroll. The fixed scroll 2 and the orbiting scroll 3 are provided with disk-shaped end plates 4 and 5 and spiral wraps 6 and 7 formed upright on the disk-shaped end plates 4 and 5, and these wraps 6 and 7 are engaged with each other inwardly. There is. The orbiting scroll 3 has a slide bearing 8 below it.
Is installed. A crank portion 9b, which is eccentric to the center of a shaft portion 9a of a crankshaft 9, is engaged with the slide bearing 8. The shaft portion 9a of the crankshaft 9 is the upper slide bearing 1 mounted on the frame 10.
1 and a lower slide bearing 12. The crankshaft 9 is rotationally driven by the electric motor 13. Due to the rotation of the crankshaft 9, the orbiting scroll 3 is rotated by the rotation prevention mechanism configured by incorporating the Oldham ring 14 between the orbiting scroll 3 and the frame 10.
Rotation is prevented. Due to this movement, the gas sucked from the suction pipe 15 is rotated by the orbiting scroll 3 and the fixed scroll 2.
Is compressed inside, and is discharged from the discharge pipe 17 through the communication hole from the discharge hole 16 of the fixed scroll 2. The load exerted on the crankshaft 9 through the orbiting scroll 3, the slide bearing 8, and the crank portion 9b of the crankshaft 9 by the compression action of the fluid trapped by the scrolls 2 and 3 is the upper slide bearing 11 and the lower slide bearing. It is received by the bearing 12. An oil supply hole 18 is narrowed in the crankshaft 9, and the oil at the bottom of the chamber 1 has a pressure in an oil sump and a pressure in a back pressure chamber 19 formed between the frame 10 and the orbiting scroll 3. The pressure difference causes the oil supply hole 18 to rise.

The structure for supplying oil to the bearings 8, 11, 12 will be described with reference to FIGS. 2 and 3. The oil supply to the bearing 8 is introduced into an oil chamber 20 formed by the crank portion 9b, the slide bearing 8 and the wall surface of the orbiting scroll 3, and then the outer peripheral surface of the crank portion 9b of the crankshaft 9 is in the axial oil supply flow direction. Oil groove 2 whose cross-sectional area gradually becomes larger
1, and lubricates the rotary sliding portion between the slide bearing 8 and the crank portion 9b of the orbiting scroll. The oil that lubricates the slide bearing 8 lubricates a thrust bearing 22 that is integrally molded in the lower portion of the slide bearing 8, and then is discharged to the back pressure chamber 20.

The upper slide bearing supporting the shaft portion 9a of the crankshaft 9 is supplied with oil by the oil supply hole 23 which is communicated with the oil supply hole 18 and the oil supply hole 23 which is communicated with the oil supply hole 23.
On the outer peripheral surface of the oil supply groove 24 in the axial direction of the oil supply flow direction, the oil supply groove 24 having a gradually larger cross section.

The oil that lubricates the slide bearing 11 flows into the thrust bearing 25 formed on the upper portion of the slide bearing 11, lubricates it, and then is discharged to the back pressure chamber 19.

The oil discharged to the back pressure chamber 19 is discharged to the meshing portion of the scrolls 2 and 3 through the pores 26 provided in the orbiting scroll. Therefore, the pressure in the back pressure chamber 19 becomes an intermediate pressure between the discharge pressure and the suction pressure. Therefore, the oil supply to the slide bearing 8 of the orbiting scroll 3 and the oil supply to the upper slide bearing 11 that supports the shaft portion 9a of the crankshaft 9 is performed by the differential pressure between the discharge pressure and the back pressure chamber.

The lower slide bearing 12 that supports the shaft portion 9a of the crankshaft 9 is supplied with oil by the oil supply hole 27 that allows the oil sucked by the oil supply hole 18 to communicate with the oil supply hole 18.
And through this, and by supplying to the oil supply groove 28 provided in the axial direction on the outer peripheral surface of the shaft portion 9a, the oil is supplied by the centrifugal force generated at the radial distance of the crankshaft 9a. The oil that lubricates the slide bearing 12 is discharged from the upper end of the slide bearing 12 through the oil drain hole 29, and is also partially discharged from the lower end of the slide bearing 12 into the chamber 1.

Of the oil supply grooves 21, 24, 28 in the axial direction,
The oil supply grooves 21 and 28 are the shaft portion 9 of the crankshaft 9.
It is arranged on a line X connecting the center C of a and the center S of the crank portion 9b, and is axially formed on the shaft surface opposite to the eccentric direction of the crank portion 9b. Further, the other oil supply groove 24 and the oil supply hole 23 are axially formed on the axial surface of the crank portion 9b on the X-ray in the eccentric direction. Each of the three oil supply grooves is provided on the shaft surface so as to form an inclined groove.

Taking the oil supply groove 21 of the slide bearing 8 as an example of the inclination, the oil supply inlet 21a is smaller than the oil supply outlet 21b in the groove cross-sectional area.

Assuming that the pressure at the bearing inlet is Pa, the volume is Va, the pressure at the bearing outlet is Pb, and the volume is Vb, the relational expression of the compressed gas is expressed by the following equation.

[0018]

[Equation 1]

From the oil flow, the pressure is Pa> Pb.
Becomes Therefore, the volume has a relationship of Va <Vb.

Although the pressure in the conventional oil supply groove having a uniform cross section is Pa> Pb, the volume change due to the pressure reduction is Va = Vb, so that the gas velocity rises and the bearing clearance increases. It will be an inflow. This causes the gas to flow into the bearing. On the other hand, it is not provided so that the cross-sectional area increases with the flow of refueling. A refrigerant is dissolved in the oil that supplies the bearing, and the oil in the bearing flows from the high pressure side to the low pressure side. With the decrease in pressure, the volume expansion of oil is almost insignificant, but the refrigerant dissolved in the bearing oil foams and becomes gas, which gets caught in the sliding part of the bearing, causing the oil film to run out,
Although the oil film thickness cannot be ensured and seizure occurs, the bubbling of the refrigerant dissolved in the bearing oil is suppressed by omitting the cross-sectional area of the oil supply groove inside the bearing so as to increase along the oil supply flow. Further, it is possible to suppress the generation of gas, eliminate the intrusion of gas into the bearing sliding portion, ensure an oil film thickness, and provide a highly reliable bearing structure.

The second embodiment shows an example of application to a lubrication structure in which a plurality of bearings are sequentially lubricated through one lubrication hole, which will be described with reference to FIG.

A frame 10 for supporting the crankshaft 9
The upper bearing 30 and the lower bearing 31 are first supplied with oil through the oil supply hole 32 that communicates with the oil supply hole 18 of the crankshaft 9 and then through the oil supply groove 33 that is provided on the outer peripheral surface of the shaft portion 9a of the crankshaft 9. Then, the lower bearing 12 is lubricated, opened to the oil chamber 34 between the bearings, then supplied to the oil supply groove 35 for the upper bearing 30, and then drained to the back pressure chamber 19. .

At this time, each oil supply groove is parallel to the surface of the shaft, and the cross-sectional area of the oil supply groove is cut off from the oil supply groove 35 of the upper bearing 30 located downstream of the oil supply groove 33 of the lower bearing 31 located upstream of the oil supply. The area is largely omitted. That is, when the arrangement of the bearings is similar to the singular with respect to the oil supply path, when the volume capable of absorbing the expansion of gas is provided between the bearings,
By increasing the cross-sectional area of the oil supply groove at the outlet from the oil supply groove at the inlet, it is possible to prevent foaming of gas in the bearing. The volume of the oil chamber 34 is determined by the thickness of the bearings and the distance between the bearings from the viewpoint of processing cost, but it is preferable that it is smaller than the expansion change of gas during refueling.

Further, as shown in FIG. 2, the shape of the oil supply groove of the upstream bearing 30 can prevent the foaming of gas in the bearing even if the cross-sectional area of the oil supply groove opened to the oil chamber 34 from the oil supply hole is increased. .

[0025]

According to the present invention, when the oil in which the refrigerant is dissolved passes through the inside of the bearing, it is possible to prevent the dissolved refrigerant from foaming due to the pressure reduction due to the flow, and to foam the bearing sliding surface. Inflow of gas can be blocked, and wear and seizure of the bearing can be prevented.

[Brief description of drawings]

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

FIG. 2 is a partial cross-sectional view of a scroll compressor showing an embodiment of the present invention.

FIG. 3 is a plan view of a crank portion showing an oil supply groove.

FIG. 4 is a partial sectional view of a scroll compressor showing another embodiment of the present invention.

[Explanation of symbols]

8 ... Sliding bearing, 9 ... Crank shaft, 9a ... Shaft part, 9b ... Crank part, 18 ... Oil supply hole.

Claims (1)

[Claims] 1. An oil supply groove is provided on the surface of the shaft in the axial direction,
By flowing the lubricating oil in the lubrication groove in the axial direction,
In a lubrication device for a bearing that lubricates between the shaft and the bearing, the lubrication groove is a groove provided so as to increase in cross-sectional area in the direction of the flow of the lubricating oil. Bearing lubrication device.