JP2701927B2 - Variable speed scroll compressor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a scroll compressor used as a refrigerant compressor for refrigeration, air conditioning, refrigerators and the like.

[Prior Art] A conventional scroll compressor is provided with a plurality of holes for liquid refrigerant injection in a fixed scroll head plate as described in JP-A-6-126396, and the liquid refrigerant on the refrigeration apparatus side is supplied from these holes. An example is disclosed in which injection is performed to reduce the temperature of the gas discharged from the compressor.

[Problems to be solved by the invention]

In recent years, scroll compressors have been driven by inverters,
Momentum to adjust the refrigerant flow rate of the compressor is increasing.

In the above prior art, the operation frequency range is about 30 Hz to about 120 Hz, the capacity control width is 1: 4, and the control width is relatively small. When it is desired to increase the capacity control width to 1:10, there is a problem regarding an appropriate liquid refrigerant flow rate control method or an appropriate compressor structure for increasing the speed of a scroll compressor.

In the present invention, a light alloy such as an aluminum alloy is used as the material of the orbiting scroll in order to achieve a high speed compressor, while a cast iron material is used on the fixed scroll side. In the case of such a combination of different materials, the temperature of the working chamber of the compressor tends to increase due to the difference in the linear expansion coefficient and the sliding characteristics between the two, and this has a bad effect on both performance and reliability. I found it experimentally. This will be described with reference to FIGS. 5 and 6. In the conventional machine, both scroll members use cast iron material or the like, and since they are made of the same material, the amount of thermal deformation of the members due to thermal expansion is substantially the same. Therefore, as shown in FIG. 5, the performance (total adiabatic efficiency) of the conventional apparatus is constant regardless of the temperature of the discharge gas temperature _Td . On the other hand, in the case of a combination of different materials targeted by the present invention,
As _Td increases, the performance decreases significantly. This axial displacement W _k of the end plate of the orbiting scroll 6 is increased T _d is rises, this is caused to lower the compression performance. This reduction in compression performance, it mechanical loss in contact root surface and the sliding of mating with the temperature rise, for example, extend relatively lap tip of the orbiting scroll side increases, also increases the panel displacement W _k As a result, a large amount of oil in the back pressure chamber (41 in FIG. 2) leaks into the suction chamber 5f through the outer peripheral portion of the head plate, so that the suction refrigerant gas is heated and the suction amount (volume efficiency) of the compressor is reduced. This is due to the decline. Then, the heating action of the suction gas by the oil increases in a low frequency range. Further, the range of the number of rotations of the motor is also expanded by expanding the capacity control width. As a result, the motor efficiency in the low-speed region is deteriorated, the heat generation is increased, the temperature inside the compressor is increased, and the above-mentioned adverse effects appear. The above phenomenon is a new technical problem caused by expanding the operation range by combining different materials. Figure 6 is technical problem (internal heating degree [Delta] T _s and a change in the pressure P _b in the back pressure chamber with the suction chamber associated with the performance degradation) of difference to conventional machine when the capacity control range around 1:10 This is shown in comparison with the case of FIG. From FIG. 6, it is apparent that the above-mentioned technical problems (deterioration of performance due to temperature rise, etc.) with the expansion of the capacity control width, which is the object of the present invention, become a serious problem especially in a low frequency region. Particularly, as the orbiting scroll is made of aluminum, the necessary range of cooling of the compressor body and the like is wider than that of the conventional machine as shown in FIG. An object of the present invention is to solve the above technical problem.

[Means for solving the problem]

The above object can be attained by obtaining a high compression performance even in a wide frequency range and stabilizing the behavior of the end plate of the orbiting scroll by disclosing a proper cooling method for the entire compressor.

That is, the feature of the present invention consists of a fixed scroll member comprising a head plate and a spiral wrap provided upright on the head plate, and a head plate and a spiral wrap provided upright on the head plate. An orbiting scroll member of a different material that is lighter than the fixed scroll member and has a larger linear expansion coefficient. The two scroll members are engaged with each other with the wrap inside, and the orbiting scroll member does not rotate with respect to the fixed scroll member. A variable speed scroll compressor in which a scroll compressor configured to perform a revolving motion is incorporated in a refrigerating device and the compressor is driven by an inverter over a wide operating frequency range, wherein a liquid injection pipe of the refrigerating device is provided. Liquid injection injection pores provided in the end plate of the fixed scroll member with high-pressure liquid refrigerant from Liquid injection means for injecting into the compression chamber of the compressor, and discharge gas temperature adjusting means for the compressor, which makes the liquid injection flow ratio variable according to the drive frequency during the operation of the compressor. Have prepared.

Another feature of the present invention is to provide a four-way valve for switching the flow direction of the compressor and the refrigerant and a decompression device for decompressing the high-pressure liquid refrigerant in the indoor and outdoor heat exchangers and the main pipe, and to cool the discharge gas. In the refrigerating apparatus having the liquid refrigerant injection pipe, the discharge gas temperature of the compressor or the superheat amount of the discharge gas temperature is set to different values depending on the case of the cooling operation and the time of the heating operation. The temperature is controlled by an electronic expansion valve installed in the liquid injection pipe.

[Action]

In the present invention, the high-pressure liquid refrigerant is decompressed to perform an injection in the compression chamber, and the flow rate of the refrigerant is controlled using an electronic expansion valve. In this case, the flow rate of the refrigerant is controlled by detecting the temperature of the discharged gas or the temperature of the oil at the lower part of the compressor in the heat-sensitive section and based on those temperatures. Second
In the scroll compressor as shown in the figure, the oil of the bottom chamber is circulated inside the compressor, and the temperature of the oil can be lowered by the cooling method described above. By reducing the temperature of the oil, the amount of oil leaking from the back pressure chamber into the suction chamber can be suppressed, and the heating of the suction gas by the oil can be reduced.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment in which a compressor 100 driven by an inverter 200 is incorporated in a refrigerant device having liquid ejection circuits 107 and 109. 90 is a four-way valve that switches the flow of the refrigerant gas. 103 and 105 are main refrigerant pipes. 102 is an outdoor heat exchanger, 104 is a decompression device (throttling mechanism), and 106 is an indoor heat exchanger. In FIG. 1, the flow of the refrigerant during the cooling operation (cooling mode) is indicated by arrows. Reference numeral 201 denotes a power supply unit. FIG. 2 and FIG. 3 show the structure of a variable speed scroll compressor having a liquid injection function. In FIG. 2, the compressor 100 is accommodated in the upper part of the sealed container 1 and the motor part 3 is accommodated in the lower part.
The interior of the sealed container 1 includes an upper chamber 1a (discharge chamber) and a motor room.
It is divided into 1b and 1c.

The compressor unit 100 forms a compression chamber (closed space) 7 by interlocking the fixed scroll member 5 and the orbiting scroll member 6 with each other. The fixed scroll member 5 is made of a cast iron material (hereinafter referred to as “FC material”) having relatively excellent self-lubricating properties.
The disk-shaped end plate 5a is provided with a wrap 5b standing upright on the end plate 5a and formed into an involute curve or a curve similar thereto, and has a discharge port 10 at the center and a suction port 16 at the outer periphery. The end plate 5a has pores for liquid injection injection.
5g penetrates. FIG. 3 shows the specific positions of the pores 5g. One fine hole 5g is provided at a portion relatively close to the discharge port 10 along the inner curve of the fixed scroll wrap 5b. For cooling the refrigerant gas and the entire compressor, one pore is sufficient. The position of the fine hole 5g in the figure has a positional relationship of communicating with the discharge pressure side about 100 degrees as the crank rotation angle. This hole position is an appropriate position in terms of performance and cooling in the case of a variable speed scroll compressor. The orbiting scroll member 6 has a disk-shaped end plate 6a and a lap 6b which stands upright and has the same shape as the wrap of the fixed scroll.
And a boss 6c formed on the anti-lapping surface of the head plate. The material of the orbiting scroll is an aluminum alloy (hereinafter referred to as an Al alloy) in order to realize a high-speed compressor.
And light alloys. This is because at high speeds, the centrifugal force acting on the orbiting scroll increases, and this force prevents an increase in load on the orbiting bearing (excessive bearing surface pressure).
Further, by using the orbiting scroll for Al, an effect peculiar to the scroll compressor that the behavior of the end plate (small displacement in the axial direction) of the orbiting scroll is stabilized with a reduction in centrifugal force appears. The frame 11 has a bearing at the center, and a rotating shaft 14 is supported on the bearing.
Is inserted into the boss 6c so as to be capable of turning motion.

The fixed scroll member 5 is fixed to the frame 11 by a plurality of bolts, and the orbiting scroll member 6 is made of aluminum alloy as base metal and is subjected to a surface treatment appropriate for the sliding properties of the aluminum materials (such as a Kanigenmekki treatment). The orbiting scroll member 6 is supported on the frame 11 by an Oldham mechanism 12 comprising an Oldham ring and an Oldham key. The orbiting scroll member 6 is configured to make a revolving motion without rotating with respect to the fixed scroll member 5. A motor shaft 14b fixed to the rotor 3b is integrally connected to the lower part of the rotating shaft 14, and the motor unit 3 is directly connected. Inlet of fixed scroll member 5
A vertical suction pipe 17 is connected to 16 through the closed container 1, and the upper chamber 1 a in which the discharge port 10 is open is connected to passages 18 a and 18 b.
Through the motor room 1b. The upper motor room 1b communicates with the lower motor room 1c via a passage 19 between the motor stator 3a and the side wall of the closed casing 1. The upper motor chamber 1b communicates with a discharge pipe 20 penetrating the closed casing 1.

11a is a frame foot for fixing the electric motor 3 to the frame.

Reference numeral 22 denotes an oil reservoir at the bottom of the closed container. In the drawing, solid arrows indicate the flow direction of the refrigerant gas, and broken arrows indicate the flow direction of the oil.

The closed container 1 is formed by an upper head plate 2a, a body part 2b, and a lower head plate 2c. For the main bearing portion 40, a rolling bearing having high reliability against oil film shortage is used.

In a space 41 (referred to as a “back pressure chamber”) surrounded by the back surface of the orbiting scroll member 6 and the frame 11, a thrust direction due to gas pressure in a plurality of closed spaces formed by both the orbiting and fixed scrolls is provided. (This force is a repelling force for pushing down the orbiting scroll member 6 downward.)
Pressure (low pressure side pressure) and a pressure intermediate to the discharge pressure (indicated by the symbol pm). This intermediate pressure is set by providing a hole 6d in the end plate 6a of the orbiting scroll 6 and guiding the gas inside the scroll to the back pressure chamber via this hole to apply a gas force to the back surface of the orbiting scroll. The method of applying the intermediate pressure is disclosed in JP-A-53-119412 and JP-A-55-37.
No. 520, etc., so a detailed description is omitted.

 Next, the flow of the lubricating oil will be described with reference to FIG.

The lubricating oil 22a is stored in the lower part of the closed container 1. Spindle 14
The lower end is immersed in oil at the bottom of the container, and has an eccentric shaft portion 14a on the upper portion of the main shaft. The eccentric shaft portion 14a engages with the orbiting scroll member 6 as a scroll compression element portion via the orbiting bearing 39. ing. In the main shaft 14, a central vertical hole 13 for supplying oil to each bearing portion is formed from the lower end of the main shaft to the upper end surface of the main shaft. Reference numeral 13a denotes an oil-lifting pipe connecting the lower end of the main shaft and an oil tank at the bottom 22. The orbiting scroll boss 6 is located below the eccentric shaft 14a.
Balance weight 8 on the upper part of the main bearing with the tip of c facing
Are integrally formed by engaging with the main shaft 14. Lubricant
The lower end of the oil pump pipe 13a immersed in 22a has a high discharge pressure Pd.
Slewing bearing 39 and main bearing on the other hand
Since the area around 40 is in an atmosphere of intermediate pressure Pm, (Pd−
Under the pressure of Pm), the lubricating oil 22a at the bottom of the container rises in the central vertical hole 13. Thus, lubrication to each bearing is
It is performed by differential pressure lubrication by center hole lubrication.

The lubricating oil 22 rising in the central vertical hole 13 is supplied to the auxiliary bearings 9 and 9 'and the main bearing 40 and the eccentric shaft 14a.
Is supplied to the revolving bearing portion via a hydraulic chamber in a gap between the bottom surface of the boss portion of the revolving scroll boss portion 6c and the upper end surface of the eccentric shaft portion 14a.

The oil supplied to the bearings 39 and 40 reaches the back pressure chamber 41.
The oil flowing into the back pressure chamber mixes with the refrigerant gas and flows out to the compression chamber 7 via the back pressure hole 6d. On the other hand, the oil in the back pressure chamber moves to the side space 11f of the adjacent orbiting scroll and returns to the back pressure chamber again, enters the sliding surface of the end plates of both scrolls, and then enters the suction chamber.
Discharge to 5f. In this way, the oil in the back pressure chamber moves to the suction chamber and, consequently, to the compression chamber. When the hot oil is mixed with the refrigerant gas, the refrigerant gas is heated and its temperature rises. The oil that has reached the compression chamber is pressurized together with the refrigerant gas, cooled together with the refrigerant gas injected through the liquid-injection pores 5g, and discharged to the discharge chamber 1a above the fixed scroll 5 and further to the motor chamber 1b. And move. In this motor room, the refrigerant gas and oil are separated, and the oil falls to the lower part of the chamber and is supplied again to each sliding portion. Thus, the oil 22a is circulating inside the compressor, and the temperature of the oil affects the temperature level of the entire compressor.

In FIG. 2, an electronic expansion valve 145 having a wide range of flow control and capable of fine-grained control is used as a pressure reducing device provided in the liquid injection piping 107, 109. In controlling the flow rate of the refrigerant of the electronic expansion valve 145, the temperature of the discharge pipe 95 (discharge gas temperature T _d ) is detected by the heat sensing unit 146, and the valve opening of the expansion valve 145 is set via the air conditioning control unit 155. Do it. The liquid injection pipe 10 is set so that the temperature of _Td or the heating degree (superheat amount) of the discharge gas itself becomes constant.
Determine the amount of liquid refrigerant flowing through 7. That performs a superheat control connexion T _d in Injiekushiyon flow. Practically, superheat amount SH (T _d ) of discharge gas temperature
Around 20-30 degrees is appropriate. The specific method of controlling T _d is
This is shown in FIG.

Figure 4 is the temperature of the oil 22a of the compressor bottom 22 as well as detected by the heat detecting unit 161, and discharge described above in having in both the gas temperature T _d proper liquid refrigerant flow (Injiekushiyon flow G _inj)
Is an embodiment in which is controlled. Reference numeral 155 denotes an air-conditioning control unit, which includes an interface such as an A / D converter and a microcomputer unit (arithmetic circuit unit). The air conditioning control unit 155 includes temperature detection units 151 and 161.
And a control valve 150. In the case of a scroll compressor, as described above, the oil 22a
Is circulated in the interior, and by setting the flow rate of the injection based on the temperature of the oil, the temperature of the scroll member can be adjusted more accurately, and the temperature of the entire compressor can be adjusted more accurately. It has been experimentally revealed that there is a correlation between the temperature of the oil in the bottom chamber and the degree of heating of the suction gas, and the above-mentioned heating of the suction gas is greatly reduced by cooling the oil temperature and, consequently, the oil in the back pressure chamber. Can be reduced. When the compressor speed increases, the opening time of the liquid refrigerant injection pores 5g becomes shorter than at low speeds, so that the _Td control cannot be properly performed by the refrigerant control using the capillary tube, which has been observed so far. According to the electronic expansion valve 145 of the present invention, since the controllability is good, sufficient cooling is possible even during high-speed operation.

The operation and effect of the present invention will be described based on FIG. 8 and FIG. For eighth conventional machine in figure is relatively narrow width of the capacity control as indicated by the broken line, (the ratio of the intake gas flow rate G _r flowing liquid Injiekushiyon flow G _inj and the suction pipe 94) and the liquid Injiekushiyon flow ratio ξ is 0.2 In this case, the compressor characteristics such as compressor input and volume efficiency have not changed. On the other hand, in a low frequency range which is the target of the present invention, for example, when H _d = 15 Hz, the injection flow ratio is ξ.
= 0.8 to 0.9, the flow rate of the injection is relatively increased to about 0.8 to 0.9, so that each performance value is dramatically improved as well as exerting the cooling effect. In the figure, each performance is represented by a ratio based on the value when ξ = 0. In particular, the improvement of the volume efficiency η _v has been remarkable. The improvement of the cooling and heating capacity is due to the fact that the efficiency of the inverter motor deteriorates at a low frequency, thereby increasing the heat load of the compressor, and the relative increase in the liquid injection amount. These specific performance improvements are achieved by suppressing the relative thermal deformation of the orbiting scroll side due to the cooling of the oil or refrigerant gas in the compressor, so that the wrap ends of both scrolls do not contact each other and reduce mechanical loss. to it, also internal heating degree to displacement W _k of the orbiting scroll due to the oil less becomes the back pressure chamber intake gas is due effect was reduced. These functions and effects are that the capacity control width is set to 1:10 and that they are directly related to the motor characteristics in the low frequency range. Becomes FIG. 9 is an explanatory diagram showing the capacity control width of the present invention as compared with that of the conventional machine. For conventional machines large drop in refrigerant flow rate G _r at low speeds, which exert large effect cooling action of the liquid Injiekushiyon case of the present invention to, it can be seen that a larger capacity control range can be established. As described above, in this embodiment, the discharge gas temperature of the compressor is also adjusted by the valve opening of the electronic expansion valve provided in the liquid injection pipe, and the liquid injection flow rate ratio (injection flow rate and Another characteristic is that the ratio of the cooling flow rate to the low-pressure suction side is made variable.

FIG. 10 shows an embodiment in which the control of the discharge gas temperature _Td differs between the cooling operation and the heating operation in the amount of superheat. In the heating operation, the flow of the refrigerant in FIG. 1 is reversed at the heat exchanger. In the figure, ΔT _dC is the superheat amount during the cooling operation, and ΔT _dH is the superheat amount during the heating operation, and the air-conditioning control unit (microcomputer unit) 155 is set so that ΔT _dH > ΔT _dC . As described above, the use of the above-described electronic expansion valve is optimal for changing the amount of superheat depending on the operation mode. By increasing ΔT _dH during the heating operation, the amount of heat generated from the electric motor 3 can be reduced.
Since the heat can be exhausted to 6, the aim is to use it effectively to improve the heating capacity.

As described above, according to the present embodiment, the scroll compressor in which the fixed scroll member is made of cast iron and the orbiting scroll is made of a material having a different linear expansion coefficient such as an aluminum alloy is incorporated in the refrigerating apparatus, and the inverter has a wide operating frequency. The variable speed scroll compressor that drives the compressor over a range has a liquid injection function for injecting the high-pressure side liquid refrigerant into the compression chamber, so that the scroll head plate is caused by a difference in expansion coefficient between the two scroll members. This has the effect of suppressing the displacement _Wk increasing effect) and realizing a wider capacity control width.

〔The invention's effect〕

 According to the present invention, the following effects can be obtained.

(1) In a compressor having a combination in which both scroll members are made of different materials, it is possible to prevent both scroll wraps from coming into contact with each other in the axial and radial directions due to a rise in temperature.
Reliability such as improved performance and prevention of galling of sliding parts can be ensured compared to conventional machines.

(2) The capacity control width of the variable speed scroll compressor can be made wider at about 1:10, and the range of the operating pressure ratio can be expanded.

(3) By setting the injection flow ratio to about イ ン = 0.8, the cooling and heating capacity can be significantly improved in a low frequency range.

(4) By controlling the liquid injection flow rate by making the superheat amount of the discharge gas temperature different between the heating operation and the cooling operation, the heating capacity can be further improved, and the comfort of the air conditioner can be improved. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a view showing a cycle configuration of a refrigerating apparatus of the present invention, FIGS. 2 and 4 are longitudinal sectional views showing an entire structure of a hermetic scroll compressor, and FIG. FIG. 5 to FIG. 7 are explanatory diagrams for explaining the problems of the prior art, FIG. 8 and FIG. 9 are explanatory diagrams showing the effects of the present invention, and FIG. It is a figure which shows the Example which made the superheat amount of the discharge gas different at the time of driving | operation. 5: fixed scroll, 6: orbiting scroll, 3 ...
Electric motor, 1b ... electric motor room, 14 ... main shaft, 17 ... suction pipe,
19 ... discharge pipe, 22 ... oil, 145 ... electronic expansion valve, 146 ...
Temperature sensing part, 107,109… liquid piping, 200…
Inverter.

Continued on the front page (72) Inventor Tetsuya Arata 502 Kandate-cho, Tsuchiura-shi, Ibaraki Pref.Hitachi, Ltd.Mechanical Research Laboratory Co., Ltd. 72) Inventor Takao Mizuno 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture Inside the Shimizu Plant of Hitachi Ltd. (56) References JP-A-63-29083 (JP, A) JP-A-52-57507 (JP, A) 1983-205059 (JP, A) Real opening 63-21787 (JP, U)

Claims (2)

(57) [Claims] A fixed scroll member comprising a head plate and a spiral wrap provided upright on the head plate; and a fixed scroll member comprising a head plate and a spiral wrap provided upright on the head plate. Equipped with a revolving scroll member made of a dissimilar material that is lighter than the scroll member and has a larger linear expansion coefficient, these two scroll members mesh with each other with the wrap inside, and the revolving scroll member rotates with respect to the fixed scroll member without rotating. A variable speed scroll compressor incorporating a scroll compressor configured to cause the compressor to drive the compressor over a wide operating frequency range with an inverter, wherein a high pressure from a liquid injection pipe of the refrigerator is used. The pressure of the liquid refrigerant passes through a liquid injection injection hole provided in the end plate portion of the fixed scroll member. Liquid injection means for injecting into the compression chamber of the compressor, and discharge gas temperature adjusting means for the compressor, which makes the liquid injection flow ratio variable according to the drive frequency during the operation of the compressor. A variable speed scroll compressor characterized by the following. 2. The electronic expansion valve according to claim 1, wherein said discharge gas temperature adjusting means is provided in said liquid injection pipe and adjusts a valve opening degree in accordance with a driving frequency. 2. The variable speed scroll compressor according to claim 1, wherein: