JP2004019620A - Scroll compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the impairing of efficiency caused by the difference in compression ratios caused by a pressure difference between compression chambers of two systems of a scroll compressor having the asymmetric shape, to obtain the ideal pressure characteristics. <P>SOLUTION: A ratio V<SB>AS</SB>/V<SB>AD</SB>of a maximum closed volume V<SB>AS</SB>and<SB></SB>a minimum closed volume V<SB>AD</SB>just before discharging, of the compression chamber A of large volume in completing the suction, is controlled to be larger than a ratio V<SB>BS</SB>/V<SB>BD</SB>of a maximum closed volume V<SB>BS</SB>and a minimum closed volume V<SB>BD</SB>just before discharging of the other compression chamber B, and smaller than V<SB>AS</SB>/V<SB>BD</SB>. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a scroll compressor used for a gas compressor such as a refrigerator and a refrigerant compressor used for refrigeration and air conditioning, as well as an air compressor, a vacuum pump, and a helium compressor.
[0002]
[Prior art]
In the prior art, the volume ratio of the asymmetric scroll shape is disclosed in JP-A-56-20701, JP-A-5-202871, and JP-A-8-21381.
[0003]
The scroll compressor disclosed in Japanese Patent Application Laid-Open No. 56-20701 is provided with an asymmetric scroll wrap in which one wrap winding angle of scroll members meshing with each other is larger than the other. In order to make the volume ratio of the compression chamber, in which the volume generated by the asymmetric scroll shape increases, equal to that of the other compression chamber, the winding start end of the scroll member is cut off.
[0004]
The scroll compressor disclosed in Japanese Patent Application Laid-Open No. 5-202871 also employs an asymmetric scroll shape. Similarly to Japanese Patent Application Laid-Open No. 56-20701, in order to make the volume ratio of the compression chamber whose volume increases increase equal to that of the other compression chamber, the preceding compression chamber is opened prior to opening the compression chamber whose volume increases when closed. An opening is provided at the discharge port.
[0005]
The scroll compressor disclosed in Japanese Patent Application Laid-Open No. 8-21381 also employs an asymmetric scroll shape. In this known document, similarly to other known documents, in order to make the volume ratio of the two compression chambers formed between the fixed scroll member and the orbiting scroll member equal, the winding start end of one scroll member is cut off. I have. Furthermore, in order to match the opening timing of the two compression chambers to the discharge port, a part of the winding start end of the fixed scroll member is cut out to make the discharge port an enlarged shape.
[0006]
[Problems to be solved by the invention]
In a scroll compressor, two systems of compression chambers are formed. If the volume ratios of the two compression chambers are significantly different, the ultimate pressure of the gas to be compressed due to the decrease in the working space in the compression stroke and the pressure at the start of compression (suction Pressure) and the ratio (referred to as compression ratio) are always different, so that one compression chamber is always over-compressed or under-compressed under any operating pressure condition. Therefore, a pressure loss due to over-compression or a backflow due to under-compression always exists under any conditions, which causes a reduction in compressor efficiency.
[0007]
In the above-mentioned prior art, it is described that the volume ratio of the compression chambers formed in two systems is the same. However, in the case of a scroll compressor having an asymmetric scroll shape, even when the volume ratio is the same, the two systems of compression chambers are formed at different timings. Always generates a pressure difference, and leakage from one compression chamber to the other compression chamber occurs. Therefore, as shown in FIG. 5, the compression chamber A having a large maximum sealed volume performs compression close to the theoretical value, but the compression chamber B having a small maximum sealed volume has a pressure larger than the theoretical value due to leakage from the compression chamber A. And the actual pressure rise in both compression chambers will differ.
[0008]
That is, the actual compression of the gas is different between the compression chambers A and B, and there is a problem that the pressure ratio in the compression chamber B is larger than that in the compression chamber A. However, in the above-mentioned Japanese Patent Application Laid-Open No. Hei 8-21381, in order to reduce the overcompression that can occur here, a cutout for correcting the discharge timing is provided at the start end side of the fixed scroll spiral body to increase the passage area at the time of discharge. ing. However, these configurations only prevent over-compression after the start of discharge, and do not solve the imbalance in pressure ratio due to the difference in pressure rise.
[0009]
The present invention has been made to solve the above-mentioned problems of the prior art.
[0010]
[Means for Solving the Problems]
The above-mentioned problem is solved by making the volume ratio of the compression chamber A having a large maximum sealed volume larger than the volume ratio of the compression chamber B having a small maximum sealed volume. Thereby, the actual pressure ratio between the compression chamber A and the compression chamber B can be made equal.
[0011]
Since this pressure ratio imbalance is caused by leakage from the compression chambers A to the compression chambers B, the pressure of both the compression chambers, the setting of the gap, the sealing method, and the oil supply to both the compression chambers when performing oil sealing. The pressure rise differs depending on the amount and the like. Therefore, how much the volume ratio of the compression chamber A is made larger than the volume ratio of the compression chamber B differs depending on the form of the compressor. In a scroll compressor having an asymmetric scroll shape, a difference in the maximum sealed volume between the two compression chambers occurs due to a difference in the winding angle of the scroll between the fixed scroll and the orbiting scroll, and thus a pressure difference occurs. Therefore, no imbalance exceeding this pressure difference occurs.
[0012]
Thus the maximum enclosed volume of V _AS of the compression chamber _A, the minimum enclosed volume of the discharge just before a V _AD, the maximum enclosed volume of V _BS of the compression chamber _B, and the minimum closed volume of the discharge just before a V _BD, the compression chambers A The volume ratio _VAS / _VAD may be determined in consideration of the state of leakage in a range larger than the volume ratio _VBS / _VBD of the compression chamber B and smaller than _VAS / _VBD . However, in practice, when the pressure rise at the time of discharge of the compression chamber B exceeds １ ／ times the theoretical pressure difference between the two compression chambers, the discharge timing of both compression chambers becomes close, and the advantage of the asymmetric shape is reduced. Therefore, it is desirable to adjust the volume ratio within this range. Therefore, the volume ratio _V AS _{/ V AD} of the compression chamber A is greater than the volume ratio _V BS _{/ V BD} of the compression chamber B, and _{(V AS + V BS) /} (2 * V BD) compression chamber to enter the smaller range A and a compression chamber B are provided.
[0013]
This volume ratio can be adjusted by any one of the method of adjusting the winding start portion of at least one of the orbiting scroll and the fixed scroll, and the method of adjusting the winding end portion of the spiral body. good. These may be performed simultaneously.
[0014]
This makes it possible to make the actual compression ratios of the compression chamber A, which starts compression first, and the compression chamber B, which starts compression later, almost equal, and realizes almost ideal pressure characteristics, The backflow loss due to loss and insufficient compression can be reduced.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
First Embodiment A first embodiment in which the present invention is applied to a hermetic scroll compressor will be described with reference to FIGS. 1 is a longitudinal sectional view of a compressor, FIG. 2 is a plan view of a scroll spiral body, and FIG. 3 is an enlarged view of a winding start portion of the spiral body of FIG.
[0016]
1 to 3, the orbiting scroll 1 includes a orbiting scroll 1a and an end plate 1b, and the fixed scroll 2 includes a fixed scroll 2a and an end plate 2b. The spiral body is formed by a circular involute curve, and the two scrolls 1 and 2 are engaged with each other to form a compression chamber A formed outside the end wrap of the orbiting scroll and a compression chamber B formed inside the wrap. And asymmetrical scroll shapes formed with a phase shift of about 180 ° with respect to the rotation of the shaft.
[0017]
First, the structure will be described. The orbiting scroll 1 is provided with a orbiting bearing 1c on the back surface, and the eccentric part 6a of the crankshaft 6 supported by the main bearing 5a of the frame 5 is inserted. An Oldham ring 7 is disposed between the orbiting scroll 1 and the frame 5, and the orbiting scroll 1 performs a orbiting motion with its rotation being restricted by the Oldham ring 7.
[0018]
The fixed scroll 2 has a discharge port 8 opened near the center. Further, the winding end of the inner curve of the fixed-side spiral body 2a is extended by about 180 ° to near the winding end of the swirling-side spiral body 1a. Therefore, when the two scrolls 1 and 2 are combined to form a compression chamber, the compression chamber A formed by being confined by the outer curve of the orbiting spiral 1a and the inner curve of the fixed spiral 2a, and the orbiting spiral The compression chamber B formed by being confined by the inner curve 1a and the outer curve of the fixed spiral body 2a has different sizes, and is formed with a phase shift of about 180 ° with respect to the rotation of the crankshaft.
[0019]
In the compression chamber A and the compression chamber B, since the compression chamber A starts compression first, when compared in the same phase, the pressure of the compression chamber A is higher than that of the compression chamber B, and the leakage of the compressed gas is smaller than the compression chamber A. To the compression chamber B. Therefore, the volume ratio of the compression chamber A is set to be larger than the volume ratio of the compression chamber B, and the volume ratio of the compression chamber A is about 2.7 and the volume ratio of the compression chamber B is about 2.4.
[0020]
The adjustment of the volume ratio is performed at the beginning of the winding of the scroll, and the inner wall surface of the scroll of the fixed scroll 2 is extended by about 180 °, so that the maximum sealed volume in the compression chamber A is increased. An extension 1c is provided which extends approximately 37 ° from the winding start angle of the outer wall surface of the spiral scroll 1 necessary for making the ratio the same as that of the compression chamber B.
[0021]
The differential pressure control mechanism 9a controls the pressure in the back pressure chamber 9 including the fixed scroll 2, the orbiting scroll 1, and the frame 5. The controlled back pressure appropriately presses the orbiting scroll 1 against the fixed scroll 2.
[0022]
The motor 10 includes a rotor 10a and a stator 10b. The rotor 10a is attached to the crankshaft 6 below the frame 5. A bearing support plate 11 is provided below the motor 10, and an auxiliary bearing 12 attached to the bearing support plate 11 supports the crankshaft 6 together with a main bearing.
[0023]
The suction pipe 13 is for taking in a working fluid such as a refrigerant gas, and communicates with the fixed scroll 2. The discharge pipe 14 is for discharging the compressed working fluid to the outside of the compressor. The closed case 15 hermetically accommodates the orbiting scroll 1, the fixed scroll 2, and the motor 10.
[0024]
Next, the operation will be described. By starting rotation of the motor 10, the crankshaft 6 rotates and the orbiting scroll member 1 starts to orbit. By this operation, both scroll scrolls 1a, 2a mesh with each other to form compression chambers A, B.
[0025]
A working fluid such as a refrigerant gas flows from the suction pipe 13 and is compressed in the compression chambers A and B. The compression chambers A and B perform a compression operation while reducing the volume in the center direction according to the rotation of the crankshaft, and are discharged from the discharge port 8 into the sealed case 15 and finally passed through the discharge pipe 14 to the outside of the compressor. Is discharged to
[0026]
The pressure in the back pressure chamber 9 rises due to the gas contained in the oil lubricating the main bearing 5a and the like, and is controlled by the differential pressure control mechanism 9a so as to have a constant pressure difference with respect to the suction pressure. This pressure becomes an intermediate pressure between the suction pressure and the discharge pressure, and presses the orbiting scroll 1 against the fixed scroll 2 to realize compression with less leakage loss.
[0027]
Next, a description will be given of the reason why the scroll compressor configured as described above can achieve almost ideal pressure characteristics and reduce power loss due to overcompression.
[0028]
The maximum closed volume of the compression chamber A is formed larger than that of the compression chamber B. After the compression chamber A is formed, the compression chamber B is formed after the crankshaft 6 is rotated by about 180 ° at a crank angle. The compression chambers A and B have the same volume, but the compression chamber A that has started compression first has a higher pressure than the compression chamber B. Therefore, the leakage of the compressed gas that occurs between the compression chambers always occurs in the direction from the compression chamber A to the compression chamber B, and the pressure in the compression chamber B is higher than the ideal compression. On the other hand, the pressure in the compression chamber A does not increase so much because the leakage is small, and almost ideal compression is performed. FIG. 6 shows the pressure changes in the compression chambers A and B at this time, which are shown with respect to the crank angle of the crankshaft 6.
[0029]
As shown in FIG. 6, although the compression chambers A and B have different volume ratios, it can be seen that the actual pressures at the start of discharge are substantially equal. Compared to FIG. 5 showing the pressure change when the volume ratios of the compression chambers A and B are equal, the overcompression loss due to the pressure rise in the compression chamber B is reduced, and almost equal compression is possible in both compression chambers. It can be.
[0030]
Actually, when the pressure rise at the time of discharge of the compression chamber B exceeds 倍 times the theoretical pressure difference between the two compression chambers, the discharge timing of both compression chambers becomes close, and the advantage of forming an asymmetric shape is reduced. It is desirable to determine the volume ratio within this range. For this reason, the volume ratio V _AS / V _AD of the compression chamber A is larger than the volume ratio V _BS / V _BD of the compression chamber B, and is smaller than (V _AS + V _BS ) / (2 * V _BD ). A and the compression chamber B further enhance the effect.
[0031]
Although the above adjustment of the volume ratio is performed by extending the outer wall surface of the scroll 1a of the orbiting scroll 1, the adjustment can be similarly performed by cutting out the outer wall surface of the scroll 2a of the fixed scroll 2. Further, the inner wall surface of the spiral body 1a of the orbiting scroll 1 may be cut off.
[0032]
FIG. 4 is a view showing a second embodiment of the present invention, and is a plan view of a scroll scroll. In FIG. 4, the orbiting scroll 1 is composed of a revolving scroll 1a and an end plate 1b, and the fixed scroll 2 is composed of a fixed scroll 2a and an end plate 2b.
[0033]
The spiral body is formed by a circular involute curve, and the two scrolls 1 and 2 are engaged with each other to form a compression chamber A formed outside the end wrap of the orbiting scroll and a compression chamber B formed inside the wrap. Is an asymmetric scroll shape that is formed out of phase with the rotation of the shaft.
[0034]
Although the volume ratio between the compression chamber A and the compression chamber B is set to about 2.7 and about 2.4 in accordance with the first embodiment described above, in this embodiment, the adjustment of the volume ratio is performed on the end side of the fixed scroll scroll. It is done in.
[0035]
A scroll shape in which the winding start side of the orbiting scroll 1a of the orbiting scroll 1 is cut so that the volume ratio becomes equal in both compression chambers when the inner wall surface of the fixed scroll 2a of the fixed scroll 2 is extended by about 180 °. On the other hand, in order to reduce the volume ratio of the compression chamber B, a notch 2d is formed by cutting the inner wall surface of the spiral 1a of the orbiting scroll 1 by about 75 °. As a result, the volume ratio between the compression chamber A and the compression chamber B can be set to about 2.7 and about 2.4, respectively, and the same effect as in the first embodiment can be exerted.
[0036]
The above adjustment of the volume ratio is performed by notching the inner wall surface of the spiral 1a of the orbiting scroll 1, but extending the inner wall surface of the spiral 2a of the fixed scroll 2 and the outer wall of the spiral 1a of the orbiting scroll 1. The adjustment can be made in the same manner. If the pressure rise during discharge of the compression chamber B exceeds 1/2 of the theoretical pressure difference between the two compression chambers, the discharge timing of the two compression chambers becomes closer and the advantage of the asymmetric shape is reduced. It is desirable to adjust the volume ratio within this range.
[0037]
As described above, the case of the scroll compressor having the spiral formed by the involute of the circle has been described. However, the scroll compressor having the spiral formed by the other curves based on the algebraic spiral or the arc is described. In this case, the same effect is obtained.
[0038]
Further, in the above embodiments, the description of the present invention has been made by taking a closed type high-pressure chamber type scroll compressor as an example. However, the effect is the same when applied to a low-pressure chamber type scroll compressor.
[0039]
According to each embodiment of the present invention, by increasing the volume ratio of the compression chamber A that starts compression first compared to the volume ratio of the compression chamber B that starts compression later, the actual rising pressure in both compression chambers can be reduced. The pressure characteristics can be made substantially equal to each other, and almost ideal pressure characteristics can be realized, and power loss due to overcompression in the compression chamber B or backflow loss due to insufficient compression in the compression chamber A can be reduced.
[0040]
【The invention's effect】
According to the present invention, it is possible to provide a high-performance scroll compressor having a significantly improved compression efficiency.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a first embodiment of the present invention.
FIG. 2 is a plan view of a scroll scroll according to the first embodiment of the present invention.
FIG. 3 is an enlarged view of a winding start portion of the spiral body of FIG. 2;
FIG. 4 is a plan view of a scroll scroll according to a second embodiment of the present invention.
FIG. 5 is a pressure characteristic diagram of a conventional scroll compressor.
FIG. 6 is a pressure characteristic diagram in the example of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Revolving scroll, 2 ... Fixed scroll, 5 ... Frame, 6 ... Crankshaft, 8 ... Discharge port, 10 ... Motor, 13 ... Suction pipe, 14 ... Discharge pipe, 15 ... Sealed case.

Claims (4)

An orbiting scroll having an end plate, a spiral body erected on the end plate and revolving without rotating, and a fixed scroll having an end plate and a spiral body erected on the end plate have two spirals. The spirals of the fixed scroll and the spiral of the orbiting scroll are different from each other in a state where the spirals are substantially 180 degrees apart from each other. In a scroll compressor having an asymmetric scroll shape in which a maximum sealed volume of two compression chambers formed by a plate and a spiral body wall is different,
The ratio V _AS / V _AD of the maximum sealed volume (V _AS ) of the compression chamber A formed by the outer wall surface of the orbiting scroll scroll and the inner wall surface of the fixed scroll, and the minimum sealed volume (V _AD ) immediately before discharge is obtained. The ratio V _BS / V _BD of the maximum sealed volume (V _BS ) of the compression chamber B formed by the inner wall surface of the orbiting scroll spiral and the outer wall surface of the fixed scroll, and the minimum sealed volume (V _BD ) immediately before discharge. A scroll compressor characterized by being larger and smaller than (V _AS + V _BS ) / (2 × V _BD ). An orbiting scroll having an end plate, a spiral body erected on the end plate and revolving without rotating, and a fixed scroll having an end plate and a spiral body erected on the end plate have two spirals. In a scroll compressor having an asymmetric scroll shape in which the bodies are meshed with each other in a state of being shifted by about 180 degrees, and the winding angle of the spiral body of the fixed scroll is larger than the winding angle of the spiral body of the orbiting scroll,
The ratio V _AS / V _AD of the maximum sealed volume (V _AS ) of the compression chamber A formed by the outer wall surface of the orbiting scroll scroll and the inner wall surface of the fixed scroll, and the minimum sealed volume (V _AD ) immediately before discharge is obtained. The ratio V _BS / V _BD of the maximum sealed volume (V _BS ) of the compression chamber B formed by the inner wall surface of the orbiting scroll spiral and the outer wall surface of the fixed scroll, and the minimum sealed volume (V _BD ) immediately before discharge. A scroll compressor characterized by being larger and smaller than (V _AS + V _BS ) / (2 × V _BD ). The scroll compressor according to claim 2, wherein a volume ratio of the compression chamber (A) is adjusted by extending or notching a winding start side of at least one of the orbiting scroll and the fixed scroll. The scroll compressor according to claim 2, wherein the volume ratio of the compression chamber (A) is adjusted by extending or notching at least one end of the orbiting scroll and the fixed scroll.

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