JPS586075B2 - Scroll compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a positive displacement fluid compression device, in particular a pair of scroll members each having a spiral body formed on one surface of a side plate, which are stacked one on top of the other so that both spiral bodies mesh with each other at different angles. The present invention relates to a scroll type compressor that compresses fluid by moving a scroll member to the center of a sealed space formed between both spiral bodies through relative circular orbital movement.

The operating principle of such a scroll compressor has been known for a long time and will be explained with reference to FIG.

The two spiral winding bodies 1 and 2 are arranged at different angles to form a spiral winding body 1,
2 are interdigitated to form a confined fluid pocket 3 from mutual contact of the spirals 1 to 2, one spiral 1 relative to the other spiral 2. The center O' of one spiral body 1 is the center of the other spiral body 2.
When the spiral body 1 is moved while inhibiting rotation so as to revolve around the center O with a radius O-O', the fluid pocket 3 gradually decreases in volume and moves toward the center.

That is, the revolution angle of the spiral body 1 is 90° from the state shown in Fig. 1a.
As shown in FIG. 1 b showing 180°, FIG. 1 c showing 180°, and FIG. The volume of the fluid pocket 3 gradually decreases as it moves toward the center.

In Figure 1 a, which has been rotated 360 degrees, both pockets have moved to the center and are connected to each other, and in Figures 1 b, c, which have been further moved by 90 degrees.
As shown in Figure 1d, the fluid pocket 3 narrows and becomes almost zero in Figure 1d.

During this time, the outer fluid pocket that began to open in Figure 1b becomes the first
In the process of moving from Figures c and d to Figure a, new fluid is taken in to create a fluid pocket.

Therefore, if sealed disk-shaped side plates are provided at both ends of the spiral bodies 1 and 2 in the axial direction, and a discharge hole as shown by 4 in FIG. The fluid is compressed and discharged from the discharge hole 4.

That is, in such a scroll type compressor, fluid compression is performed by reducing the volume due to movement of a fluid pocket formed between both spiral bodies.

This fluid pocket is formed between both spirals by the line contact between the spirals and the contact between the tip surface of the spiral and the surface of the other side plate, and these contact areas are caused by the circular orbit movement of one scroll member. The fluid inside the fluid pocket is compressed by sliding movement.

Here, the compression cycle will be explained with reference to Fig. 2. Fig. 2 shows the pressure state in the fluid pocket with respect to the crank angle, and illustrates the case where one compression cycle ends in two revolutions of the crank. are doing.

The compression cycle begins when the outermost end of the spiral body comes into contact with the wall surface of the opposite spiral body, and the suction ends (k in Fig. 2).
The internal pressure gradually increases while the volume inside the fluid pocket decreases until the crank angle reaches 2π (point 1).

However, immediately after point 1 (point m), the two fluid pockets that have been compressed up to this point communicate with the central chamber that communicates with the discharge chamber, forming one pocket.

If the instantaneous discharge hole is not equipped with a valve device, the pressure inside the pocket will rise rapidly until it matches the discharge pressure, but if a valve device is installed, the high pressure in the central chamber will increase rapidly. The fluid and the compressed fluid in the pocket are mixed, resulting in a slight pressure rise, and are compressed by the movement of the spiral body until the discharge pressure is reached (point n). When the discharge pressure is reached, the valve device operates and the pressure in the central chamber increases. High pressure fluid will flow into the discharge chamber.

Therefore, after the central chamber communicates with the discharge chamber, it reaches point o while maintaining a constant pressure.

In this way, one compression cycle is completed at a crank angle of 4π, and in the middle of one compression cycle (in the example shown in FIG. 2, at a crank angle of 2π), another compression cycle k'-1 is completed.
'-m'-...) starts and the cycle continues sequentially to perform the compression operation, but since the line contact between the spiral bodies is made in multiple pairs, all contacts must be made completely. is difficult.

If a gap is created at these contact points, compressed fluid will leak during the compression operation, resulting in a decrease in volumetric efficiency, ie, refrigerating capacity.

This fluid leakage becomes a problem especially where there is a large pressure difference before and after the contact point.

In addition, when fluid leakage from the high-pressure part of the central chamber to the next chamber increases, the pressure inside the fluid pocket increases as shown by the broken line in Figure 2, and the horsepower consumption for the compression operation, that is, the torque required for the compression operation, increases. There was a need to improve sealing performance in the vicinity.

By the way, the curve of the spiral body is normally pitched (a1 in Fig. 3).
-a2, a2-an or b1-b2, b2-b.

The two spiral bodies are brought into line contact at points a1 to an and b1 to bn using a circular expansion line with a constant distance (distance between them). When a relative circular orbital motion is applied to one of the scroll members by the driven crank of the scroll member, the required turning radius of the scroll member is determined by the contact point having the smallest pitch among the errors.

In other words, the wall surface of the spiral wound body having the smallest pitch only contacts the wall surface of the opposite spiral wound body, and gaps are created at all other points where contact should be made, resulting in leakage of compressed fluid.

If this is to be avoided, extremely high precision will be required in the processing of the spiral wound body.

On the other hand, within a range of limited accuracy, the point on the spiral wall at which the orbital radius is determined varies depending on the individual barracks of the part, so fluid leaks can occur from the central chamber to the next chamber. Some occur in chambers closer to the suction surface.

Therefore the performance of the individual compressor (volume efficiency and coefficient of performance)
It is not suitable for mass production because the variation in the results is very large.

Furthermore, even when the above-mentioned error-free scroll members are combined to perform a compression operation, heat is generated during operation, and the temperature around the scroll members increases, and the scroll members also naturally expand thermally, but the temperature rises. If it is uniform over the entire scroll member, there will be no problem because the line contact area between the spiral windings will change evenly, but in actual use, the temperature near the discharge part will rise. is larger than the temperature rise at the outer periphery, so distortion occurs in the spiral due to thermal expansion, and a gap may be created at the wire contact area, and this gap, combined with the gap between the walls of the spiral body, This caused fluid leakage within the high-pressure fluid pocket.

The present invention intentionally prevents fluid leakage in order to prevent fluid leakage from occurring in the vicinity of the central chamber due to errors in wall surface machining of the spiral body or thermal expansion strain caused by temperature rise. The purpose is to generate it in areas that are less affected by it, thereby stabilizing the performance of the product.

The present invention will be explained below with reference to the drawings showing embodiments.

FIG. 4 is a sectional view of a scroll type compressor showing an embodiment of the present invention, and the compressor has a compressor housing 10 consisting of a front end plate 11 and a cup-shaped portion 12 installed therein.

A fixed scroll member 13 and a movable scroll member 14 are disposed inside the housing 10.

Here, the fixed scroll member 13 generally includes a side plate 131, a spiral body 132 formed on one surface thereof, and a spiral body 132 formed on one side of the side plate 131.
32, and a leg portion 133 provided on the side plate 131 on the opposite side from the cup-shaped portion 12. The bottom 121 of the portion 12 is fixed on the inner wall.

Furthermore, the side plate 131 of the fixed scroll member 13 fixed within the cup-shaped portion 12 is connected to the outer circumferential surface of the fixed scroll member 13 and the cup-shaped portion 12.
The internal space of the cup-shaped portion 12 is partitioned into a discharge chamber 16 and a suction chamber 17 by sealing between the inner walls of the cup-shaped portion 12 .

The movable scroll member 14 is composed of a side plate 141 and a spiral body 142 formed on one side of the side plate 141.
are combined with the spiral body 132 of the fixed scroll member 13 so as to be able to perform the action as explained in FIG.

The movable scroll member 14 does not rotate in accordance with the rotation of the main shaft 18 which is rotatably supported by the front end plate 11, but rotates on a circular orbit as explained in FIG. is joined to.

Here, a detailed description of the mechanism for causing the movable scroll member 14 to revolve while inhibiting its rotation will be omitted since it can be implemented by various known mechanisms.

When the movable scroll member 14 is driven, the fluid flowing into the suction chamber 17 in the casing 10 from the suction port 19 formed on the cup-shaped member 12 flows into both spiral bodies 132,1.
42, and is gradually compressed and sent to the center as the movable scroll member 14 moves, and is fed to the side plate 131 of the fixed scroll member 13.
It is fed under pressure to the discharge chamber 16 from the discharge port 134 bored at the top,
Furthermore, it is sent out to the outside of the casing 10 from the discharge port 20.

Here, the spiral body 132 of both scroll members 13,14
, 142, as shown in Fig. 5, the inner wall surface is the wall thickness from the inner end A of the spiral body to point B, which is returned by 2π at the expansion and opening angle, and the wall thickness from point B to the outermost end D of the inner wall surface of the spiral body. Change the thickness B-D
The outer wall surface is formed to be slightly a thinner than the A-B section, and the outer wall surface has a wall thickness from the inner end A to a point C that contacts the above-mentioned point B, and from the point C to the outermost end E of the spiral body outer wall surface. By changing the wall thickness up to the wall thickness, the C-E portion is formed to be slightly thinner than the A-C portion.

For this reason, the A-B part of the inner wall surface of the spiral body and the A-B part of the outer wall surface.
When parts C are operated so that they are in line contact with each other, parts B-D and C-
A gap 2a will be created at the line contact portion of the E section.

On the other hand, the structure is such that line contact between the spiral bodies is reliably made at a point 2π apart from the inner end of the spiral bodies at an expansion/opening angle, that is, at a portion that becomes a high-pressure pocket.

The present invention having such a configuration has both spiral bodies 132,
The wall thickness near the center of 142 is made slightly thicker than other parts to ensure perfect line contact, so even if a slight error △E occurs in the wall surface machining of other parts,
As long as ΔE<2a, there is no effect on the seal at the center, and since the pressure difference is small for leakage from the non-contact portion at the outer periphery, the effect on volumetric efficiency can be suppressed to a small level.

Further, the thin winding strain caused by the rise in temperature that occurs during operation of the compressor is also absorbed by the difference a in wall thickness.

As described above, the present invention changes the wall thickness of the spiral body constituting the scroll member between the central part and the outer peripheral part, and by forming the wall thickness of the outer peripheral part slightly thinner, the high-pressure fluid pocket is Since the line contact between the spiral winding bodies is ensured, it is possible to suppress the decrease in volumetric efficiency due to errors caused in the processing of the scroll member, and it is also possible to suppress variations in performance due to variations in errors to a small level. It is.

It is also possible to suppress fluid leakage due to differences in thermal expansion changes due to temperature rise that occurs during operation of the compressor.

Further, since the sliding portion due to the line contact between the spiral winding bodies is limited, countermeasures against wear of the sliding portion can be easily taken by localized measures.

[Brief explanation of drawings]

1A to 1D are diagrams for explaining the compression principle of the scroll type compressor according to the present invention. A diagram for explaining a cycle, FIG. 3 is an explanatory diagram showing a contact state when a conventional spiral wound body is used, and FIG. 4 is a longitudinal sectional view of a scroll compressor showing an embodiment of the present invention. FIG. 5 is an explanatory diagram showing a contact state when a spiral wound body according to an embodiment of the present invention is used. 13.14...Scroll member, 131.141...
- Side plate, 132, 142... spiral body.

Claims (1)

[Claims] 1. A pair of scroll members each having a spiral wound body formed on one side plate are fitted so that both spirals engage with each other at different angles, and the wall surfaces are in contact to form a sealed fluid pocket between the spiral bodies. By stacking one scroll member on the other and moving it in a relative circular orbit while preventing rotation, the fluid pocket is moved toward the center of the spiral body while its volume decreases, resulting in a unidirectional fluid compression effect. In a scroll compressor that performs A scroll type compressor characterized in that the wall thickness of the spiral coil is formed to be slightly thicker than the wall thickness of the spiral coil from then on to the outermost end of the spiral coil.