JPH0219678A - Scroll compressor - Google Patents

Abstract

PURPOSE:To reduce compression power loss due to leakage of refrigerant gas by making the width of a rolling scroll spiral protrusion larger than the diameter of a fluid bypass hole having specific area and making wider than the width of a fixed scroll spiral protrusion. CONSTITUTION:There is a relation Wo>Wf, between the width Wf of a fixed scroll spiral protrusion 1b and the width Wo of a rolling scroll spiral protrusion 2b. There is also a relation Wo>d, between the width Wo of the rolling scroll spiral protrusion 2b and the diameter (d) of a fluid bypass hole 14, and the area of the fluid bypass hole 14 is set such that the flow speed will be 0.15-0.35 times that of the sound. By such arrangement, refrigerant gas fed from an inside compression chamber 51 into an outside compression chamber 52 does not leak and thereby the refrigerant gas is not re-compressed, resulting in suppression of power loss.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a scroll compressor.

[Conventional technology]

FIG. 5 shows a scroll compressor consisting of a conventional totally hermetic refrigerant compressor proposed in, for example, Japanese Patent Application No. 61-283406. In the figure, 1 is a fixed scroll; A spiral protrusion 1b is provided on the lower surface. Reference numeral 2 denotes an oscillating scroll, which has a spiral protrusion 2b on the upper surface of a base plate portion 2a, and a oscillating shaft portion 2c protruding from the lower part of the center of the base plate portion 2a. 5 each spiral protrusion 1b;
2b is a compression chamber formed by combining them, 3 is each scroll 1
．． 2 is a suction port formed on the outer periphery of 2, 4 is a fixed scroll 1
A discharge port 6 is a main shaft provided in the center of the base plate portion 1a, and an eccentric hole 6b is provided in the large diameter portion 6a at the upper end. 7 is a swing bearing fitted into the eccentric hole 6b and supports the swing shaft portion 2C in the radial direction; 8.9 is a motor rotor and motor stator that drive the main shaft 6; and 10 is a swing scroll when the main shaft 6 is driven. 2 is an Oldham joint that restricts rotational movement without rotation; 11 is a closed container that accommodates each component;
12 is a suction pipe fixed to the closed container 11, and 13 is a discharge pipe fixed to the fixed scroll 1, which sends the compressed gas from the discharge port 4 to the outside of the closed container 1. , 25 supports the fixed scroll 1, and the oscillating scroll 2 is placed in the recess 25a.
This is a bracket that rotatably supports the large diameter portion 6a of the main shaft 6 via a bearing 26, and has an oil return hole 25b and a gas passage 25c. Reference numeral 27 denotes a bracket 25, which supports the motor stator 9 and rotatably supports the main shaft 6, and includes an oil return hole 27a, a gas passage 27b,
27c. 6c is an eccentric oil supply hole provided eccentrically through the main shaft 6, 28 is an oil cap attached to the lower end of the main shaft 6, and 29 is lubricating oil.

In the conventional scroll compressor described above, when the motor rotor 9 rotates, the main shaft 6 rotates, and the oscillating scroll 2 rotates.
revolves while being prevented from rotating by Oldham's joint 10. As a result, the gas passages 27c, 27 from the suction pipe 12
Inhalation gas is taken into the compression chamber 5 through the suction port 3, b, 25c, and the suction port 3, and is gradually compressed and discharged from the discharge port 4 into the discharge pipe 13.

Furthermore, in the figure, 14 is a fluid bypass hole provided in the base plate portion 1a of the fixed scroll 10, 15 is a valve seat formed around the fluid bypass hole 14, and 16 is a discharge hole provided in the base plate portion 1a. One end of the hole opens to the outside of the fixed scroll 1 communicating with the suction pressure space, and the other end communicates with a slit 23 formed concentrically around the fluid bypass hole 14 .

Reference numeral 17 denotes a bypass valve, which is, for example, a circular plate-shaped valve made of hardened and polished steel plate used as a valve material for a refrigerant compressor. A valve seat plug 18 closes the upper part of the valve seat 15 and serves as a stopper for the bypass valve 17. 19 is a valve seat space between the valve seat 15 and the valve seat plug 18, 20 is a communication hole provided in the center of the valve seat plug 18, and 21 is a valve for guiding suction pressure and discharge pressure by switching a three-way solenoid valve (not shown) or the like. This is pressure piping, and is fixed to the communication hole 20 of the valve seat plug 18 and the piping hole 22 of the closed container 11 by brazing or the like. In a scroll compressor, the fixed scroll 1 and the oscillating scroll 2 are combined to form a plurality of symmetrical pairs of compression chambers 5 at the same time, so the fluid bypass holes 14 are also symmetrical corresponding to at least one pair of compression chambers 5. It is necessary to install a pair at appropriate locations.

Furthermore, a slit 23 is formed concentrically outside the fluid bypass hole 14, and this slit 23 and the valve seat space 19
The fluid bypass hole 14 and the discharge hole 16 are communicated with each other through the fluid bypass hole 14 and the discharge hole 16. In addition, a coil spring 24 is provided in the slit 23 so that when the pressure in the valve seat space 19 becomes low, the bypass valve 17 is smoothly pushed up and comes into close contact with the valve seat plug 18 to prevent the bypass valve 17 from flapping. to be placed.

In this conventional scroll compressor, when the compressor is operated at maximum capacity without capacity control, the discharge pressure is guided to the outer end of the pressure pipe 21 by switching the three-way solenoid valve (not shown), etc. The pressure in the space 19 becomes the discharge pressure,
When the discharge pressure acts on the bypass valve 17, the bypass valve 17 is pressed downward and comes into close contact with the valve seat 15, and the discharge hole 16 communicating with the fluid bypass hole 14 and the slit 23 is simultaneously closed by the bypass valve 17, and the compression chamber is closed. The fluid No. 5 is discharged to the outside of the compressor via the discharge pressure 14 and the discharge pipe 13.

When controlling the capacity of the compressor, the suction pressure is introduced to the outer end of the pressure pipe 21 by switching a three-way solenoid valve (not shown), so that the pressure in the valve seat space 19 becomes the suction pressure. Since the fluid bypass hole 14 is provided during the compression process of the compression chamber 5, the pressure in the compression chamber 5 communicating with the fluid bypass hole 14 is higher than the suction pressure. Further, as described above, the coil spring 24 is attached so as to push up the pass valve 17. Therefore, the bypass valve 17 is pushed upward and is held in contact with the valve seat plug 18,
The fluid bypass hole 14 and the discharge hole 16 communicate with each other, and a part of the fluid in the compression chamber 5 is discharged through the fluid bypass hole 14 and the discharge hole 16 to the outside of the fixed scroll 1 communicating with the suction space, and the fluid inside the compression chamber 5 is discharged to the outside of the fixed scroll 1 communicating with the suction space. The compression capacity of is controlled. The capacity of the fluid discharged to the outside of the fixed scroll l is determined by the fluid bypass hole 1.
4, the cross-sectional area and number of slits 23, the diameter and number of discharge holes 16, and the spiral protrusion 1 of fixed scroll 1.
It can be controlled by the position relative to b. Note that the position of the fluid bypass hole 14 is such that the fluid is completely confined by the fixed scroll l and the swinging scroll 2 and the compression chamber 5 is
It is movable within a range from the most upstream position where the compression chamber 5 is formed to the position immediately before the compression chamber 5 communicates with the discharge port 4.

[Problem to be solved by the invention]

Since the conventional scroll compressor is configured as described above, once the amount of refrigerant bypass during capacity control is determined, the position of the fluid bypass hole is determined. However, during capacity control, the refrigerant gas outside where the suction gas is trapped is removed from the fluid bypass hole 14. Valve seat space 19. It is discharged to the outside of the compression chamber through the slit 23 and the discharge hole 16, but at this time, the inlet pressure loss at the compression chamber side opening of the bypass hole 14 and the discharge route (
(The passage area of the fluid bypass hole is the smallest in the discharge path)
Due to the pressure drop, the pressure inside the outer compression chamber increases somewhat compared to the suction gas pressure. Therefore, the area of the fluid bypass hole is designed to reduce the pressure loss in the flow path when the refrigerant bypasses through the bypass hole in order to obtain a predetermined bypass amount during capacity control and to reduce the compression of the bypassed refrigerant gas. So, the velocity of the refrigerant flow is 0.1 of the sound velocity of the refrigerant.
It was determined experimentally to be about 5 to 0.35.

As a result, when trying to increase the bypass amount during capacity control, it is necessary to increase the area of the bypass hole, and at this time, if the fluid bypass hole 14 is a round hole with good workability, its diameter will fluctuate. In some cases, the width was larger than the spiral protrusion width of the moving scroll 2.

For example, in the case of a 4 m spiral protrusion with a 40% bypass, the hole will be about 6 mm in diameter.

As mentioned above, the width of the oscillating scroll volute is set so that the refrigerant to be bypassed during capacity control flows out of the fixed scroll 1 from the compression chamber with a small flow loss in the direction perpendicular to the periphery of the volute of the fluid bypass hole. In this case, consider operation without capacity control, that is, at maximum capacity. This state is shown in Figs. 3 and 4. Fig. 3 shows the fluid bypass hole 14 and the fixed scroll!! FIG. 4 is a cross-sectional plan view showing the relationship between the spiral protrusions lb, 2b and the compression chamber 5, and FIG. 4 is an enlarged sectional view taken along the line IV-IV in FIG. However, if the width of the fluid bypass hole 14 in the direction perpendicular to the periphery of the spiral projection is larger than the width of the oscillating scroll spiral projection, as shown below, the compression chamber 5 close to the discharge port is Compressed refrigerant gas leaks into chamber 52. This will be explained with reference to FIG.

Considering the fixed scroll, the spiral protrusions 1b and 2b of the oscillating scroll, and the fluid bypass hole 14 in the positional relationship shown in FIG. 3, the compression chamber 51 on the side near the discharge port and the compression chamber 52 on the outside are The refrigerant gas, which is communicated through the bypass hole 14 and compressed by - degrees, leaks to the compression chamber 52 on the low pressure side as shown by the arrow. As a result, during maximum operation, recompression of the refrigerant gas occurs, which increases the power to compress the refrigerant gas, resulting in a reduction in compression efficiency.

This invention was made to solve the above-mentioned problems, and aims to reduce compression power loss due to leakage of refrigerant gas during maximum capacity operation, as well as reduce compression power loss due to refrigerant bypassed during capacity control. The purpose of the present invention is to reduce the compression power loss due to the pressure increase on the low-pressure side of the bypassed gas caused by the pressure loss of the gas, and to obtain a scroll compressor with high efficiency.

[Means to solve the problem]

The scroll compressor according to the present invention includes a fixed scroll in which a spiral protrusion is provided at the lower part of the base plate part and a discharge port is provided in the middle 6 part of the base plate part, and a fixed scroll in which the spiral protrusion is provided on the base plate part. In a scroll compressor that includes an oscillating scroll in which a volute protrusion combines a vortex of a fixed scroll with a protrusion to form a compression chamber, and compresses fluid in the compression chamber by the oscillation of the oscillating scroll, the base plate of the fixed scroll is a valve seat space that is provided and introduced so that suction pressure and discharge pressure can be switched;
a fluid bypass hole that is provided in the base plate of the fixed scroll and communicates between the compression chamber and the valve seat space before communicating with the discharge port;
A discharge hole provided in the fixed scroll base plate communicates with the fluid bypass hole through a concentric slit formed on the outside of the fluid bypass hole and a valve seat space, and a discharge hole provided in the valve seat space to which discharge pressure is introduced. a bypass valve that closes the fluid bypass hole and the discharge hole when suction pressure is introduced, and opens the fluid bypass hole and the discharge hole when suction pressure is introduced; and a coil number horn that pushes the bypass valve into the slit. , the area of the fluid bypass hole is set such that the velocity of the flow of the bypassed refrigerant gas is 0.15 to 0.35 with respect to the sonic speed of the refrigerant, and the width of the oscillating scroll spiral protrusion is larger than the diameter of the fluid bypass hole; The width of the fixed scroll spiral protrusion is also wider than that of the fixed scroll spiral protrusion.

[For production]

In this invention, without increasing the pressure loss of the refrigerant gas bypassing through the fluid bypass hole during capacity control,
Gas compression power due to leakage of refrigerant gas from the inner compression chamber to the outer compression chamber during maximum capacity operation can be reduced.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows a cross-sectional view of the same part as in Figure 4 of the scroll compressor according to the present invention, where 1 is a fixed scroll, the width of the spiral protrusion 1b is W, and 14 is a fluid bypass hole, the diameter of which is W. Let it be d. 2 is an oscillating scroll,
If the width of the spiral projection 2b is wo, both spiral projections 1b
, 2b have the relationship w, ,>w.

FIG. 2 is a cross-sectional view showing the relationship between the fluid bypass hole 14, the oscillating scroll spiral protrusion 2b, and the compression chamber 5 at maximum capacity. According to this, the width W of the oscillating scroll spiral protrusion 2b,
There is a relationship w, > d with respect to the diameter d of the fluid bypass hole 14, and in the fluid bypass hole 14, the flow velocity when the refrigerant bypass amount flows is 0.1 with respect to the sound velocity of the refrigerant.
It is set to be 5 to 0.35.

Further, FIG. 2 shows the positional relationship between the outer compression chamber 52 formed by the combination of the fluid bypass hole 14, the fixed scroll 1, and the oscillating scroll 2, and the compression chamber 51 located one space inside. As is clear from this figure, the compressed refrigerant gas does not leak or expand from the inner compression chamber 51 to the outer compression chamber 52, and there is no recompression of the refrigerant gas.
Power loss can be suppressed.

In addition, in this invention, an involute is used for the spiral shape, and even if the widths of the spiral protrusions 1b and 2b of both scrolls are different, if the oscillating radius of the oscillating scroll 2 is adjusted and selected, they will always come into contact at the sides of the volute. .

The x and y coordinates of the fixed scroll outer peripheral surface and the oscillating scroll inner peripheral surface are Xt, yt, and Xo.

As yG, the base circle radius of the involute is a, and the tooth width angle of the width of the fixed scroll spiral protrusion is α(w t ”20α
)2 The tooth width angle of the width of the oscillating scroll spiral protrusion is β(W,
=20β), the swing radius is ε, and the revolution angle is r.
For any involute angle θ, it is expressed as . Then, by partially differentiating each with respect to θ, the slope dy/dx of the tangent at an arbitrary involute angle becomes different, and is the same for both the fixed scroll and the oscillating scroll.

Also, from the properties of involutes, when the involute angle θ is advanced by 2π, the distance between the spiral protrusions is 2πa,
Therefore, the radius of revolution ε is expressed as 2"a-2(a"°β' = a(yc-6-β))
= If so, the spiral protrusions of the oscillating scroll are always fixed, and the outer and inner circumferences of the scrolls can be in contact with each other, and the inner and outer circumferences can be in contact with each other.

Furthermore, when the oscillating scroll material is made of aluminum and the fixed scroll material is made of cast iron, the elastic modulus E is 7000 kg/md for aluminum and 13000 kg/md for cast iron.
kg/-, so if we try to make the strength of the spiral protrusion the same (the pressure of compressed gas acts on the side surface), the wall thickness is such that the second moment of area ■ is proportional to the cube of the wall thickness, Since the bending stiffness is expressed by EXI, in the above numerical example, the wall thickness of the spiral protrusion of the aluminum oscillating scroll is 1.23 times the wall thickness of the spiral protrusion of the cast iron fixed scroll. In addition, the specific gravity is 2.7 for aluminum and 7.2 for cast iron, so even considering the increase in wall thickness, the weight of the oscillating scroll is approximately A of that of conventional cast iron, and in order to maintain balance, the main shaft and The weight of the balancer added to the rotor is also reduced, and the excitation force is also reduced, resulting in a lighter weight, less vibration, and a spiral protrusion width W larger than the diameter d of the fluid bypass hole.
It is possible to produce an aluminum oscillating scroll with 0.
This is particularly advantageous when the fixed scroll is provided with a fluid bypass hole, such as in this type of scroll compressor with a bypass type capacity control mechanism.

〔Effect of the invention〕

As explained above, according to the present invention, the area of the fluid bypass hole is set such that the velocity of the flow of the bypassed refrigerant gas is 0.15 to 0.35 relative to the sound velocity of the refrigerant, and the width of the oscillating scroll spiral protrusion is set to By making the diameter larger than the diameter of the fluid bypass hole and wider than the width of the fixed scroll spiral protrusion, it is possible to reduce compression power loss due to leakage of refrigerant gas during maximum capacity operation, which results in a highly efficient scroll compressor. Become.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the vicinity of the fluid bypass hole of a scroll compressor according to an embodiment of the present invention, FIG. 2 is a cross-sectional plan view showing the relationship between the compression chamber, the fluid bypass hole, and the spiral protrusion, and FIG.
The figure is a cross-sectional plan view showing the relationship between the compression chamber, fluid bypass hole, and spiral protrusion in a conventional scroll compressor, Figure 4 is a cross-sectional view taken along the FIG. 1... Fixed scroll, 1a... Base plate part, ib...
- Spiral protrusion, 2... Oscillating scroll, 2a... Base plate portion, 2b... Spiral protrusion, 4... Discharge port, 5... Compression chamber, 14... Fluid bypass hole, 16 ...Exhaust hole,
17... Bypass valve, 19... Valve seat space, 23...
・Slit, 24...Coil spring. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] A fixed scroll is provided with a spiral protrusion at the bottom of the base plate part and has a discharge port in the center of the base plate part, and a spiral protrusion is provided on the base plate part and this spiral protrusion is combined with the spiral protrusion of the fixed scroll. In a scroll compressor, which is equipped with an oscillating scroll that forms a compression chamber, and which compresses the fluid in the compression chamber by the oscillation of the oscillating scroll, it is installed on the base plate of the fixed scroll and can switch between suction pressure and discharge pressure. The valve seat space to be introduced, a fluid bypass hole that communicates the valve seat space with the compression chamber provided in the base plate of the fixed scroll and before communicating with the discharge port, and a concentric circle formed on the outside of this fluid bypass hole. A discharge hole provided in the fixed scroll base plate communicates with the fluid bypass hole through the slit and the valve seat space, and a discharge hole provided in the valve seat space that communicates with the fluid bypass body bypass hole and the discharge hole when discharge pressure is introduced. and a coil spring that pushes up the bypass valve into the slit, and the velocity of the flow of refrigerant gas bypassing the area of the fluid bypass hole is 0.15 to 0.15 to the sonic speed of the refrigerant.
0.35, and the width of the oscillating scroll volute is larger than the diameter of the fluid bypass hole and wider than the width of the fixed scroll volute.