JPS5813184A - Scroll type compressor - Google Patents

Abstract

PURPOSE:To restrain the leakage of fluid caused by the difference of the change of thermal expansion by changing the thickness of the wall of a scroll body between its central and circumferential part to construct the wall thickness of the circumferential part a little thinner for ensuring the linear contact between scroll bodies in a pocket part of high-pressure fluid. CONSTITUTION:Walls of two scroll bodies near their central parts are constructed a little thicker than in other parts for obtaining perfect linear contact. In this construction, even if a small error is given in the wall processing in other part, it cannot influence the seal at the central part, and even for the leakage of the non-contact part in the circumferential part, the small difference of pressure allows to restrain the influence to the volumetric efficiency at a low level. meanwhile, even when the temperature is risen during the operation of a compressor, since perfect linear contact can be obtained in the parts almost equal in the thermal rising rate, the generation of a gap caused by the difference of the change of thermal expansion at a high-pressure part can be prevented for also restraining the leakage of fluid.

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. Scroll-type compression in which the sealed fluid pocket formed between both spiral bodies is moved to the center of the spiral body by the relative circular motion of the members, reducing the volume and compressing the fluid. It's about machines.

The operating principle of 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,
One spiral 1 is connected to the other spiral 2 in an interdigitated manner so as to form a confined fluid pocket 3 between the mutual contacts of the spirals 2.
While prohibiting the rotation of the spiral winding body 1, so that the center (0) of one spiral winding body 1 revolves around the center (0) of the other spiral winding body 2 with a radius O-0'. Upon movement, the fluid pocket 3 moves toward the center while gradually decreasing its volume. That is, from the state of FIG. 1(a), FIG. 1(b) shows that the revolution angle of the spiral body 1 is 90°, and
As shown in FIG. In Figure 1 (a), which is rotated 360 degrees, both pockets are moved to the center and connected to each other, and then further moved by 90 degrees in Figures 1 (b) and (C). (d
), the fluid pocket 6 is narrowed, as shown in FIG.
), the force is almost zero. During this time, the outer fluid pocket that started to open in Figure 1(b) changes from Figure 1(C)(d) to (a).
In the process of transferring, new fluid is taken in and a fluid pocket is created.

Therefore, if sealed disc-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 in 4 in Fig. 1 is provided in the center of one of the side plates, the outer periphery in the radial direction can be The fluid taken in is compressed and discharged from the discharge hole 4:1.

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 moves due to the line contact between both spiral bodies and the contact between the tip end surface of the spiral body and the surface of the other side plate, thereby compressing the fluid within the fluid pocket.

゛Here, to explain the compression cycle with reference to Fig. 2, Fig. 2 shows the pressure state in the fluid pocket with respect to the crank angle, and exemplifies the case where one compression cycle consists of two revolutions of the crank. are doing.

The compression cycle begins when the outermost end of the spiral body comes into contact with the opposing wall surface of the spiral body, and the suction ends (A in Figure 2).
The internal pressure gradually increases while the volume inside the fluid pocket decreases until the crank angle becomes 2π (point Q). However, immediately after point ρ (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 this 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 fluid in the central chamber will The compressed fluid in the pocket is mixed, causing a slight pressure rise, and is 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 central chamber of high-pressure fluid flows into the discharge chamber. Therefore, after the central chamber communicates with the discharge chamber, it reaches the zero point while maintaining a constant pressure. In this way, when one compression cycle is completed at a crank angle of 4π, there is a gap in the middle of one compression cycle (in the example shown in Fig. 2, the crank angle is 2π).
π) and another compression cycle (a'T , *-m#-
...) starts and the cycle continues sequentially to perform the compression operation, but since the wire contact between the spiral coils is made in multiple pairs, it is difficult to make all the contacts perfectly. . If a gap is created at these points of contact, compressed fluid will leak during the banking operation, resulting in a reduction in volumetric efficiency, ie, refrigeration capacity. This fluid leakage becomes a problem especially where there is a large pressure difference before and after the contact point. Also, if fluid leakage from the high pressure part of the central chamber to the next chamber increases, the second
As shown by diagonal lines in the figure, the pressure inside the fluid pocket increases and the horsepower consumption for the compression operation, that is, the torque required for the compression operation increases, so it was necessary to improve the sealing performance near the central chamber.

By the way, the curve of the spiral body is usually pitched (diagonal lines -a2, a2-an or -b2, b2-bn in Fig. 2).
The two spiral bodies are brought into line contact at points a1 to an and ~bn using a circular expansion line with a constant distance (distance between When a driven crank such as a pusher gives relative circular orbital motion to one 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 processing the thin roll.

On the other hand, within a limited range of accuracy, the point at which the trajectory radius is determined for the spiral type differs depending on individual variations in the parts, so if the fluid leak occurs 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 temperature is very large, and even when the above-mentioned error-free scroll members are combined to perform compression operation, heat is generated during operation and the temperature around the scroll members decreases. As the temperature rises, the scroll member will naturally expand thermally, but if the temperature rise is uniform for the entire scroll member, no problem will occur because the line contact between the spirals will change evenly. However, in actual use, the rise in temperature near the discharge part is greater than the rise in temperature at the outer periphery, which causes distortion in the spiral due to thermal expansion, and the wire A gap may be formed at the contact portion, and this gap, together with the gap between the walls of the spiral body, causes fluid leakage in 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 of this 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. It has Uzing 10.

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 the side plate 1
61, a spiral body 132 formed on one surface thereof, and a leg portion 1 provided on the side plate 131 on the opposite side from the spiral body 132.
33, and the leg portion 163 is connected to the cup-shaped portion 12.
It is fixed onto the inner wall of the bottom part 121 of the cup-shaped part 12 by a port 15 which penetrates the cup-shaped part 12 from the outside and is screwed into the hole. Furthermore, the side plate 161 of the fixed scroll member 13 fixed within the cup-shaped portion 12 seals between its outer peripheral surface and the inner wall of the cup-shaped portion 12, thereby dividing the internal space of the cup-shaped portion 12 into the discharge chamber 16 and the suction chamber. '17.

The movable scroll member 14 includes a side plate 141 and a spiral body 142 formed on one surface thereof.
are combined with the spiral body 162 of the fixed scroll member 16 so as to be able to perform the action as explained in FIG. The movable scroll member 14 rotates in accordance with the rotation of the main shaft 18, which is rotatably supported by the front end play (11). 18
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 as the movable scroll member 14 moves, and is sent to the center of the side plate 131 of the fixed scroll member 16.
It is fed under pressure to the discharge chamber 16 from the discharge port 134 bored at the top,
Further, it is delivered out of the casing 10 from the discharge port 20.

Here, the spiral body 132 of both scroll members 13 and 14
．． 142, as shown in Fig. 5(a), only the outer wall has a step at point C, which is unwound by about 2π radians at the expansion and opening angle from the inner end A, and the A-C part is connected to the C-E part. Although it is formed to be slightly thicker (a) to effect contact, there will be a gap (a) at the C-E portion. However, in the compression line of a scroll compressor, the part C-E corresponds to the relatively low pressure part in Figure 2 (this is a characteristic diagram for the case with a valve device). If the pressure difference before and after the tangent is small and the gap (α) is minute, the influence of fluid leakage will be small. In the example, the section m-1 where high-pressure compression is performed is A in Fig. 5(a).
-' Corresponds to part C, but this part A-C is the above gap (
α) maintains a good seal.

In FIG. 2, if the seal in the high-pressure part of the spiral banknote type is defective, the internal pressure will rise quickly due to gas blow-by, as shown by A-ρ1m'-n'. At this time, the shaded area corresponds to energy loss during compression. Therefore, sealing the high pressure (m-n) part is important for reducing energy loss, and the embodiments are as follows:
The aim is to ensure the sealing of this important area.

By the way, the position M'':: of the above-mentioned point C and the below-mentioned point B does not need to be exact.

In addition, here, the level difference is not necessarily as shown in Fig. 5(a).
It is not necessary to provide them on the outer walls of the spiral bodies 132, 142, and the same effect can be expected even if they are provided only at point B on the inner wall side corresponding to point C, as shown in FIG. 2(b). However, these steps are not necessarily step-like changes as shown in FIGS. 5(a) and 5(b), but may be arbitrary change curves. Actually, when the spiral wound body 132.degree. 142 is processed by a milling machine, the end mill 100 used has a shape as shown in FIG. It is impossible to process j42 into a step-like shape, resulting in a shape as shown in the figure.

Furthermore, as shown in FIG. 5(d), the wall thickness of the spiral bodies 132, 142 may be processed to gradually decrease from near point B or zero point to point E. Of course questions B-E and C-
The distance between E may be gradually decreased. In this case (α′) is B
It is a function of the expansion/opening angle that is 0 at the point or point C and gradually increases outside of it. In this embodiment, the dimensional error absorption effect is small in the portion where the wall thickness decreases little, but the change in wall thickness between and is a reasonable gap change in response to the pressure change in the first part in FIG. Furthermore, considering that the temperature expansion is large near the center, α can be changed at a rate that compensates for the dimensional change due to the temperature expansion.

In the present invention having such a configuration, both spiral bodies 132
, -142, the wall thickness near the center is made slightly thicker than other parts to ensure perfect line contact.
Even if a slight error △E occurs in the wall surface machining of other parts, it will not affect the seal in the center as long as △E < a, and there will be no pressure difference even if there is leakage from non-contact parts on the outer periphery. Since it is small, the effect on volumetric efficiency can be kept small.

Also, regarding the temperature rise that occurs while the compressor is operating,
Since the parts where the rate of rise is almost the same are the parts where perfect line contact can be obtained, it is possible to prevent gaps from occurring due to differences in changes due to thermal expansion in the high pressure part.

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 bodies is ensured, it is possible to reduce compression power loss due to errors in machining of the scroll member and the degree of temperature rise caused by this, and also to suppress a decrease in volumetric efficiency. At the same time, variations in performance due to variations in errors can also be suppressed.

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 the drawing]

FIGS. 1(a) to 1(d) are diagrams for explaining the compression principle of the scroll compressor according to the present invention; FIGS. 1(a) to 1(d) are diagrams showing states at different angular positions; The figure is a diagram explaining the compression cycle of a scroll type compressor, and Figure 3 is an explanatory diagram showing the contact state when using a conventional spiral wound body.
FIG. 4 is a longitudinal sectional view of a scroll compressor showing one embodiment of the present invention, and FIGS. 5(a), (b), (C), and (d) are explanatory diagrams showing several embodiments of the present invention. be. (16), (14)...scroll member (131),
(141)... Side plate (132), (142)... Spiral body Fig. 1 (a)) Fig. 1 (C), 7! /. (d)

Claims (1)

[Claims] A pair of scroll members each having a spiral body formed on one surface of a side plate are stacked so that both spirals mesh with each other at different angles, and the wall surfaces are in contact to form a sealed fluid pocket between the spiral bodies. By moving one of the scroll members in a relative circular orbit while preventing rotation, the fluid pocket is moved toward the center of the spiral body with a decrease in volume, thereby producing a unidirectional fluid compression effect. In a scroll compressor that performs 1. A scroll compressor characterized in that the wall thickness is gradually reduced, or only the inner wall side or the outer wall side is thinner.