JP2000087892A - Two-stage compressor and air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the shortage of inflow of gas to high stage side compression mechanism from low stage side compression mechanism and to prevent the excessive outflow of gas from low stage side compression mechanism. SOLUTION: Low stage side compression mechanism 5L and high stage side compression mechanism 5H are stored in a casing 31 to constitute a two- stage compressor for compressing a low pressure fluid in two stages by both compression mechanisms 5L, 5H to discharge a high pressure fluid. A discharge port 53 of the low stage side compression mechanism 5L and an intake port 52 of the high stage side compression mechanism 5H are communicated by an intermediate passage 55. An injection pipe 2B for introducing an intermediate pressure refrigerant of intermediate pressure between a low pressure fluid and a high pressure fluid is communicated with the intermediate passage 55. The cylinder volume of the high stage side compression mechanism 5H is set to be not more than 85% of the cylinder volume of the low stage side compression mechanism 5L.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-stage compressor and an air conditioner, and more particularly to a measure for improving efficiency.

[0002]

2. Description of the Related Art Conventionally, a two-stage compressor has been disclosed in
As disclosed in Japanese Patent Publication No. 087074, there is a configuration in which a low-stage compression mechanism and a high-stage compression mechanism are provided in a casing.

[0003] In the low-stage compression mechanism, a suction-side refrigerant pipe of a refrigerant circuit is connected to a suction port to supply low-pressure refrigerant. On the other hand, the discharge port of the low-stage compression mechanism is connected to the suction port of the high-stage compression mechanism via an intermediate passage in the casing. The discharge port of the high-stage compression mechanism is opened to a high-pressure chamber in the casing, and the suction-side refrigerant pipe of the refrigerant circuit is connected to the high-pressure chamber of the casing.

[0004] The low-stage compression mechanism sucks the low-pressure refrigerant in the refrigerant circuit and compresses the refrigerant into an intermediate-pressure refrigerant. Thereafter, the high-stage compression mechanism sucks the intermediate-pressure refrigerant, and the high-stage compression mechanism compresses the intermediate-pressure refrigerant into a high-pressure refrigerant and discharges the compressed high-pressure refrigerant.

[0005] In this two-stage compressor, the temperature of the discharged refrigerant is suppressed from rising.

[0006]

However, in the above-described two-stage compressor, the relationship between the cylinder capacity of the high-stage compression mechanism and the cylinder volume of the low-stage compression mechanism is not considered at all, and the optimum condition is not considered. There is a problem that it is not necessarily operated at a high speed and the efficiency is not always high.

In particular, in the case of two-stage compression, since the specific volume (gas density) of the low-stage compression mechanism and the high-stage compression mechanism are different, the volume of the silidane between the low-stage compression mechanism and the high-stage compression mechanism is different. In this case, there is a problem that the amount of refrigerant flowing from the low-stage compression mechanism to the high-stage compression mechanism is insufficient, and the mass flow rate of the discharged refrigerant is not stable.

Conversely, if the cylinder capacity of the high-stage compression mechanism is smaller than the cylinder capacity of the low-stage compression mechanism more than necessary, the amount of refrigerant flowing out of the low-stage compression mechanism becomes excessive. At that time, the intermediate-pressure refrigerant is guided from the refrigerant circuit to the two-stage compressor, and the intermediate-pressure refrigerant and the refrigerant discharged from the low-stage compression mechanism are combined and supplied to the high-stage compression mechanism so that the economizer effect is exhibited. There is something that is. However, in this case, the intermediate-pressure refrigerant does not flow or decreases from the gas-liquid separator of the refrigerant circuit, and as a result, the economizer effect is not exhibited.

SUMMARY OF THE INVENTION The present invention has been made in view of the above point, and it is possible to prevent a shortage of gas inflow from a low-stage compression mechanism to a high-stage compression mechanism and to prevent gas from flowing from the low-stage compression mechanism. It is an object of the present invention to prevent an excessive amount of outflow and ensure that an intermediate pressure fluid flows in.

[0010]

SUMMARY OF THE INVENTION-Summary of the Invention-In the present invention, the relationship between the cylinder capacity of a low-stage compression mechanism and the cylinder volume of a high-stage compression mechanism is appropriately set.

Means taken by the present invention in order to achieve the above object are as follows: -Solution means- Specifically, as shown in FIG. A two-stage compressor in which a compression mechanism (5L) and a high-stage compression mechanism (5H) are housed, and the two-stage compression mechanism (5L, 5H) compresses the low-pressure fluid in two stages and discharges the high-pressure fluid. . Further, the discharge port (53) of the low-stage compression mechanism (5L) and the suction port (52) of the high-stage compression mechanism (5H) communicate with each other via an intermediate passage (55). ) Communicates with an introduction pipe (2B) for introducing an intermediate pressure fluid intermediate between the low pressure fluid and the high pressure fluid. In addition, the cylinder capacity of the high-stage compression mechanism (5H) is set to 85% or less of the silidan volume of the low-stage compression mechanism (5L).

A second solution is the first solution, wherein the low-stage compression mechanism (5L) and the high-stage compression mechanism (5H) are the silidan of the low-stage compression mechanism (5L). The cylinder capacity of the high-stage compression mechanism (5H) is 65% of the volume
It is configured for a low compression ratio set within a larger range of 85% or less.

[0013] In a third aspect of the present invention, in the first aspect, the low-stage compression mechanism (5L) and the high-stage compression mechanism (5H) are formed of a silidium of the low-stage compression mechanism (5L). The cylinder capacity of the high-stage compression mechanism (5H) is 45% of the volume
And a high compression ratio set in the range of 65% to 65%.

The fourth solution means is the two-stage compressor (30) according to any one of the first to third solution means.
And a heat source side heat exchanger (22), a first expansion mechanism (E1), a gas-liquid separator (23), a second expansion mechanism (E2), and a use side heat exchanger (24) are connected in this order, Circulating refrigerant circuit (2
0), the intermediate-pressure refrigerant is supplied between the two-stage compressor (30) and the gas-liquid separator (23).
To the two-stage compressor (30).

According to the above-mentioned specific matter, in the present solution, when the low-stage compression mechanism (5L) and the high-stage compression mechanism (5H) are driven, for example, in the fourth solution, the refrigerant circuit ( The low-pressure refrigerant returning from 20) flows into the low-stage compression mechanism (5L) and is compressed.

On the other hand, since the intermediate-pressure refrigerant is supplied to the intermediate passage (55) from the gas-liquid separator (23), the intermediate-pressure refrigerant discharged from the low-stage compression mechanism (5L) and the gas-liquid separator (2
The intermediate-pressure refrigerant from 3) merges in the intermediate passage (55) and flows into the high-stage compression mechanism (5H).

In the high-stage compression mechanism (5H), the intermediate-pressure refrigerant is compressed, and the high-pressure refrigerant flows out to the refrigerant circuit (20), and the refrigerant circulates in the refrigerant circuit (20).

At the time of the two-stage compression, the high-stage compression mechanism (5
H) The volume of the cylinder chamber (6s) is
Since the volume of the cylinder chamber (6s) in L) is set to 85% or less, the inflow of the high-stage compression mechanism (5H) is insufficient, or conversely, the outflow of the low-stage compression mechanism (5L). The amount is not excessive.

[0019]

Therefore, according to the present invention, the cylinder capacity of the high-stage compression mechanism (5H) is reduced by the low-stage compression mechanism (5H).
The low-stage compression mechanism (5L) and the high-stage compression mechanism (5H) can be operated in an optimal state because a predetermined ratio is set for the cylinder volume of L), and high-efficiency operation can be performed. Can be.

That is, since the amount of refrigerant flowing into the high-stage compression mechanism (5H) does not become insufficient, the mass flow rate of refrigerant gas discharged from the high-stage compression mechanism (5H) is stabilized, and the efficiency is improved. Can be achieved.

Further, since the discharge amount of the refrigerant from the low-stage compression mechanism (5L) does not become excessive, a predetermined intermediate-pressure refrigerant flows reliably from the gas-liquid separator (23), so that the economizer effect is reduced. It can be surely demonstrated.

According to the second solution, the cylinder capacity of the high-stage compression mechanism (5H) is reduced by the low-stage compression mechanism (5H).
L) greater than 65% and 85
%, The highest efficiency can be exhibited for a low compression ratio operated under general air-conditioning temperature conditions.

According to the third solution, the cylinder capacity of the high-stage compression mechanism (5H) is reduced by the low-stage compression mechanism (5H).
When the volume is set in the range of 45% to 65% with respect to the cylinder volume of L), the highest efficiency can be exhibited for a high compression ratio operated under cold district conditions.

Further, according to the fourth solution, the pressure (intermediate pressure) of the intermediate-pressure refrigerant can be maintained at the optimum intermediate pressure, so that the economizer effect can be maximized and the efficiency can be greatly improved. Can be planned. That is, since the cooling capacity and the heating capacity can be improved, the COP
(Coefficient of performance) can be improved.

[0025]

Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 2, the air conditioner (10)
Is a heat pump type air conditioner, which is configured to be switchable between a cooling operation and a heating operation.

The refrigerant circuit (20) of the air conditioner (10)
Are a compressor (30), a four-way switching valve (21), an outdoor heat exchanger (22) as a heat source side heat exchanger, a first expansion valve (E1) as a first expansion mechanism, and a gas-liquid separator ( 23), a second expansion valve (E2) serving as a second expansion mechanism, an indoor heat exchanger (24) serving as a use-side heat exchanger, and an accumulator (25) are sequentially connected by a refrigerant pipe (26). Equipped with a refrigerant circuit (2M).

The four-way switching valve (21) switches between a cooling operation indicated by a solid line in FIG. 2 and a heating operation indicated by a broken line in FIG.

The refrigerant circuit (20) is provided with an injection pipe (2B). The injection pipe (2B) is an introduction pipe for injecting an intermediate-pressure gas refrigerant, which is an intermediate-pressure fluid, into the compressor (30), and has one end connected to the gas-liquid separator (23) and the other end connected to the compressor (30). ). That is, the gas-liquid separator (23) stores an intermediate-pressure refrigerant having an intermediate pressure between the condensing pressure of the refrigerant as the high-pressure fluid and the evaporation pressure of the refrigerant as the low-pressure fluid. The injection pipe (2B) converts the gas-phase intermediate-pressure gas refrigerant of the gas-liquid separator (23) into a compressor (30).
Injection.

The first expansion valve (E1) and the second expansion valve (E2)
Is composed of a motor-operated valve whose opening can be adjusted freely. And
The intermediate-pressure refrigerant depressurized by the first expansion valve (E1) or the second expansion valve (E2) is stored in the gas-liquid separator (23).

The compressor (30) is configured to control the operating capacity steplessly or in multiple steps. The compressor (30) is a two-stage compressor as a feature of the present invention,
As shown in FIG. 1, a motor (40), a low-stage compression mechanism (5L) and a high-stage compression mechanism (5H) are housed in a closed casing (31).

The motor (40) includes a stator (41) fixed to an inner peripheral surface of a casing (31), and a stator (41).
And a rotor (42) disposed at the center of the rotor.
The drive shaft (32) is connected to the center of the rotor (42). The drive shaft (32) extends downward and is connected to the low-stage compression mechanism (5L) and the high-stage compression mechanism (5H).

The bottom of the casing (31) is formed as an oil reservoir (33) for lubricating oil. The lower end of the drive shaft (32) is immersed in the lubricating oil of the oil reservoir (33). ing.
Although not shown, a centrifugal oil pump (not shown) is provided at the lower end of the drive shaft (32), and lubricating oil passes through an oil supply passage (34) in the drive shaft (32) and is compressed at a lower stage. It is supplied to the sliding parts of the mechanism (5L) and the high-stage compression mechanism (5H).

The low-stage compression mechanism (5L) and the high-stage compression mechanism (5H) are located below the motor (40) and are arranged vertically. Each of the low-stage compression mechanism (5L) and the high-stage compression mechanism (5H) is constituted by a so-called swing type rotary compressor.

The low-stage compression mechanism (5L) and the high-stage compression mechanism (5H) have substantially the same configuration, and the high-stage compression mechanism (5H) is provided above the low-stage compression mechanism (5L). Is arranged. As shown in FIG. 3, the compression mechanisms (5L, 5H) each include a piston (61) housed in a cylinder chamber (6s) formed in a cylinder (60). A middle plate (6 m) is provided between the cylinders (60) of the two compression mechanisms (5L, 5H), and a lower plate (6d) is provided on the lower surface of the low-stage cylinder (60) and closed. The upper surface of the high-stage side cylinder (60) is provided with an upper plate (6u) and is closed.

On the other hand, the piston (61) of each of the compression mechanisms (5L, 5H) is formed in an annular shape, and the eccentric shaft (62) is rotatably fitted therein. The eccentric shaft (62) is formed eccentric to the drive shaft (32).

Each cylinder (60) has a suction passage (51,
52) is formed, and one end of the suction passage (51, 52) opens to the cylinder chamber (6s) to form a suction port. The middle plate (6m) has a discharge passage (53) for the low-stage compression mechanism (5L), while the upper plate (6u) has a discharge passage (54) for the high-stage compression mechanism (5H). ) Is formed,
One end of each of the discharge passages (53, 54) opens to the cylinder chamber (6s) to form a discharge port. Although not shown, each of the discharge passages (53, 54) is provided with a discharge valve that opens a discharge port when a predetermined discharge pressure is reached.

In the cylinder (60), a cylindrical bush hole (63) is formed between the suction port and the discharge port so as to open in the cylinder chamber (6s). The piston (61) has a blade (6
4) is integrally formed. The tip side of the blade (64) has a pair of swinging bushes (6
b) has been inserted through.

The blade (64) is provided in the cylinder chamber (6s).
To the low-pressure chamber and the discharge passage (5
It is divided into a high-pressure chamber that leads to (3, 54). The piston (61) is connected to the swinging bush (6) through the blade (64).
It is configured to swing around the fulcrum b) and revolve around the cylinder chamber (6s) to compress the refrigerant.

The suction passage (5) of the low-stage compression mechanism (5L)
1) is connected to the suction-side refrigerant pipe (2r) of the main refrigerant circuit (2M). The suction-side refrigerant pipe (2r) is configured as a suction pipe that supplies a low-pressure gas refrigerant to the low-stage compression mechanism (5L).

On the other hand, an annular intermediate passage (55) is formed in the middle plate (6m). Then, the injection pipe (2B) is connected to the middle plate (6m), and the injection pipe (2B) communicates with the intermediate passage (55). That is, the intermediate passage (55) is supplied with an intermediate-pressure gas refrigerant and is configured to have an intermediate-pressure atmosphere.

The discharge passage (53) of the low-stage compression mechanism (5L) communicates with the intermediate passage (55), while the suction passage (52) of the high-stage compression mechanism (5H) communicates with the intermediate passage (55). ), And the intermediate-pressure refrigerant is supplied to the high-stage compression mechanism (5H).

The discharge passage (54) of the high-stage compression mechanism (5H) is opened in the casing (31), and the inside of the casing (31) is configured to have a high-pressure atmosphere. The upper part of the casing (31) has a main refrigerant circuit (2
M) is connected to the discharge side refrigerant pipe (2d). The discharge-side refrigerant pipe (2d) is configured as a discharge pipe that discharges a high-pressure gas refrigerant.

The upper plate (6u) is provided with a muffler (65) for covering the discharge passage (54) of the high-stage compression mechanism (5H).

The change in the characteristics of the refrigerant in the refrigerant circuit (20) will be described in detail with reference to FIG.

First, the refrigerant in the compressor (30) is
It is compressed from the low pressure state at the point 1 to the high pressure state of the condensation pressure at the point 4. This high-pressure gas refrigerant is condensed in the outdoor heat exchanger (22) or the indoor heat exchanger (24) and becomes a high-pressure liquid refrigerant at point 5.
This high-pressure liquid refrigerant is decompressed to an intermediate-pressure refrigerant by the first expansion valve (E1) or the second expansion valve (E2) to the point 6 and stored in the gas-liquid separator (23). ) To separate into intermediate-pressure liquid refrigerant and intermediate-pressure gas refrigerant.

The separated intermediate-pressure gas refrigerant is injected into the compressor (30) (see point 3) via the injection pipe (2B), while the intermediate-pressure liquid refrigerant is supplied from point 7 to the second expansion valve ( E2) or the first expansion valve (E1) reduces the pressure to the low-pressure two-phase refrigerant to point 8. The low-pressure two-phase refrigerant evaporates in the indoor heat exchanger (24) or the outdoor heat exchanger (22), changes to point 1, and returns to the compressor (30).

As a feature of the present invention, the cylinder capacity of the high-stage compression mechanism (5H) is set to 85% or less of the cylinder volume of the low-stage compression mechanism (5L). For example, the cylinder (60) in the high-stage compression mechanism (5H) is formed smaller in height than the cylinder (60) in the low-stage compression mechanism (5L).

More specifically, the high-stage compression mechanism (5
In the air conditioner (10) applied to the general air-conditioning temperature condition, the cylinder volume of H) is set within a range of more than 65% and 85% or less of the cylinder volume of the low-stage compression mechanism (5L). It is configured for a low compression ratio.

The cylinder capacity of the high-stage compression mechanism (5H) is 45% to 65% of the cylinder volume of the low-stage compression mechanism (5L) in the air conditioner (10) applied to cold regions. Is configured for a high compression ratio set within the range.

The basic principle of the cylinder volume relationship between the high-stage compression mechanism (5H) and the low-stage compression mechanism (5L) will be described in detail with reference to the Mollier line in FIG.

First, the dryness x6 (wt%) of the intermediate-pressure refrigerant (see point 6 in FIG. 4) flowing into the gas-liquid separator (23) is expressed by the following equation.

[0053]

(Equation 1)

Is as follows. H is the enthalpy of each point shown in FIG.

Next, the refrigerant circulation amount G1 (kg / h) of the low-stage compression mechanism (5L) is set such that the rotation speed is a (rph), the cylinder volume is V1 (m ³ ), and the suction gas density is If ρs (kg / m ³ ),

[0056]

(Equation 2)

Is as follows.

The circulation amount G2 (kg / h) of the intermediate-pressure refrigerant is obtained from the heat balance (economizer heat balance) of the gas-liquid separator (23) as follows:

[0059]

(Equation 3)

Is as follows.

The enthalpy H3 at the point 3 on the Mollier diagram in FIG.

[0062]

(Equation 4)

Is obtained.

On the other hand, when the cylinder capacity of the high-stage compression mechanism (5H) is V2 (m ³ ), the above equations (2) and (3)
Therefore, the refrigerant circulation amount G2 is as follows:

[0065]

(Equation 5)

Is obtained.

Since the refrigerant circulation amount of the high-stage compression mechanism (5H) is (G1 + G2), if the suction gas density of the high-stage compression mechanism (5H) is ρm (kg / m ³ ), The following equation is derived from the refrigerant circulation amount (G1 + G2),

[0068]

(Equation 6)

The cylinder volume ratio (V1 / V2) between the high-stage compression mechanism (5H) and the low-stage compression mechanism (5L) is derived.

In the above-described air conditioner (10), the pressure of the intermediate-pressure refrigerant (the intermediate pressure Pm), which is theoretically the most efficient
Is the high pressure as PH and the low pressure as PL,

[0071]

Equation 7

Is obtained.

Under various operating conditions where the condensing temperature Tc and the evaporating temperature Te are different, the cylinder volume ratio of the low-stage compression mechanism (5L) and the high-stage compression mechanism (5H) is determined by changing the two types of refrigerant (R410A, R22). ) Is as shown in Table 1.

[0074]

[Table 1]

Based on the above Table 1, the high-stage compression mechanism (5H)
The cylinder volume of the cylinder of the low-stage compression mechanism (5L) is greater than 65% and 85% or less,
Or, it is set in the range of 45% to 65%. still,
The optimum intermediate pressure Pm in Table 1 is the COP during the cooling operation.
It is the pressure value when (coefficient of performance) is highest.

Next, in the above-mentioned theoretical formulas and the like, the compressor efficiency and the volumetric efficiency are both set to 100%. However, in consideration of the actual work of the compressor, etc., the compressor of the low-stage compression mechanism (5L) is used. Assuming that the efficiency and the volumetric efficiency are ηtad1 and ηv1, and the compressor efficiency and the volumetric efficiency of the high-stage compression mechanism (5H) are ηtad2 and ηv2, the characteristic change of the refrigerant is as shown by the broken line in the Mollier diagram of FIG. Become.

Therefore, the refrigerant circulation amount G1 '(kg / h) of the low-stage compression mechanism (5L) corresponding to the above equation (2) is:

[0078]

(Equation 8)

Is obtained.

The enthalpy H2 'at point 2' in FIG.
Is as follows:

[0081]

[Equation 9]

Is obtained.

The circulation amount G2 ′ (kg / h) of the intermediate-pressure refrigerant corresponding to the above equation (3) is obtained from the heat balance (economizer heat balance) of the gas-liquid separator (23) as follows.

[0084]

(Equation 10)

## EQU10 ##

The enthalpy H 3 ′ at the point 3 ′ on the Mollier diagram in FIG. 5 corresponds to the above equation (4), and from the heat balance at this point 3 ′,

[0087]

[Equation 11]

Is as follows.

The enthalpy H4 'at the point 4' on the Mollier diagram in FIG. 5 is used to find the entropy s3 'at the enthalpy H3' and the enthalpy H4 ^* at the intersection of the high pressure PH of the refrigerant and the entropy s3 '. Then,

[0090]

(Equation 12)

Is obtained.

On the other hand, assuming that the cylinder volume of the high-stage compression mechanism (5H) is V2 (m ³ ), the high-stage compression mechanism (5H)
Is (G1 ′ + G2 ′), and if the suction gas density of the high-stage compression mechanism (5H) is ρm3 ′ (kg / m ³ ), it corresponds to the above equation (6). Circulation volume (G1 '+
G2 '), the following equation is derived.

[0093]

(Equation 13)

The cylinder volume ratio (V1 / V2) between the high-stage compression mechanism (5H) and the low-stage compression mechanism (5L) is derived.

Therefore, if the intermediate pressure Pm of the intermediate-pressure refrigerant is represented by the above equation (7), the cylinder volume ratio of the high-stage compression mechanism (5H) and the low-stage compression mechanism under various operating conditions is calculated. The derivation is as follows.

First, using refrigerant R410A, ηtad1 = 6
In the case of 0%, ηtad2 = 60%, ηv1 = 90%, ηv2 = 90%, the cylinder volume ratio is as shown in Table 2.

[0097]

[Table 2]

Using refrigerant R410A, η tad1 = 7
In the case of 0%, ηtad2 = 70%, ηv1 = 95%, ηv2 = 95%, the cylinder volume ratio is as shown in Table 3.

[0099]

[Table 3]

Further, using refrigerant R22, η tad1 = 60
%, Ηtad2 = 60%, ηv1 = 90%, ηv2 = 90%, the cylinder volume ratio is as shown in Table 4.

[0101]

[Table 4]

As shown in Tables 2 to 4, under general air-conditioning temperature conditions (Tc / Te = 42/3, 46 / 1.5), the cylinder volume ratio is 65% to 70%, (Tc / Te =
42 / -25), the cylinder volume ratio is 45% to 5%.
5%.

Based on the above-described principle, in the present invention, the cylinder capacity of the high-stage compression mechanism (5H) is set to 85% or less of the cylinder volume of the low-stage compression mechanism (5L). The COP improvement rates in Tables 2 to 4 are as follows:
This is a value during the cooling operation.

-Air Conditioning Operation- Next, the air conditioning operation of the air conditioner (10) will be described.

First, during the indoor cooling operation, the four-way switching valve (21) is switched to the solid line side in FIG. The refrigerant discharged from the compressor (30) exchanges heat with outside air in the outdoor heat exchanger (22) and condenses. This liquid refrigerant is reduced in pressure by the first expansion valve (E1), becomes an intermediate-pressure refrigerant having an intermediate pressure between the condensing pressure and the evaporation pressure, and accumulates in the gas-liquid separator (23).

Among the intermediate-pressure refrigerant in the gas-liquid separator (23), the intermediate-pressure liquid refrigerant is decompressed by the second expansion valve (E2), and then exchanges heat with indoor air in the indoor heat exchanger (24). To evaporate and cool the room air. Thereafter, the gas refrigerant returns to the compressor (30) via the accumulator (25), and performs the refrigerant circulation operation.

On the other hand, during the heating operation, the four-way switching valve (21)
Is switched to the broken line side in FIG. The refrigerant discharged from the compressor (30) exchanges heat with the indoor air in the indoor heat exchanger (24) and condenses while heating the indoor air. Thereafter, the liquid refrigerant is reduced in pressure by the second expansion valve (E2), becomes an intermediate-pressure refrigerant, and accumulates in the gas-liquid separator (23).

Among the intermediate-pressure refrigerants in the gas-liquid separator (23), the intermediate-pressure liquid refrigerant is decompressed by the first expansion valve (E1), and then exchanges heat with the outside air in the outdoor heat exchanger (22). And evaporate. Thereafter, the gas refrigerant returns to the compressor (30) via the accumulator (25), and performs the refrigerant circulation operation.

In the above-described air-conditioning operation, since the injection pipe (2B) is provided, the gas-liquid separator (2B) is provided.
The intermediate-pressure gas refrigerant of 3) is injected into the compressor (30).

Changes in the characteristics of the refrigerant during the cooling operation and the heating operation are as shown in FIG. 4 or FIG. Then, during the heating operation, the refrigerant flowing through the indoor heat exchanger (24) serving as the condenser is added with the intermediate-pressure gas refrigerant G2, so that the refrigerant circulation amount increases and the heating capacity improves.

On the other hand, during the cooling operation, the low-pressure two-phase refrigerant at point 8 has an increased enthalpy from point 6 to point 7, so that the amount of heat of the refrigerant evaporated in the indoor heat exchanger (24) increases. The cooling capacity is improved.

Further, as shown in FIG. 6, the power of the X portion is reduced.

Next, the compression operation of the compressor (30) will be described.

The drive shaft (32) is driven by driving the motor (40).
Rotates, and the pistons (61) of the low-stage compression mechanism (5L) and the high-stage compression mechanism (5H) swing around the center of the bush hole (63) as a fulcrum to revolve. And the main refrigerant circuit (2M)
The low-pressure gas refrigerant returning from the accumulator (25) flows into the cylinder chamber (6s) from the suction passage (51) of the low-stage compression mechanism (5L), and is compressed by the swing of the piston (61).

On the other hand, since the intermediate-pressure refrigerant is supplied to the intermediate passage (55) from the gas-liquid separator (23), the discharge valve of the low-stage compression mechanism (5L) is located inside the cylinder chamber (6s). It opens when the refrigerant pressure reaches an intermediate pressure. After that, the intermediate-pressure refrigerant discharged from the low-stage compression mechanism (5L) and the intermediate-pressure refrigerant supplied from the gas-liquid separator (23) merge in the intermediate passage (55), and the high-stage compression mechanism (5H) Into the cylinder chamber (6s).

At this time, the volume of the cylinder chamber (6s) of the high-stage compression mechanism (5H) is set to be 85% or less of the volume of the cylinder chamber (6s) of the low-stage compression mechanism (5L). In addition, the inflow of the high-stage compression mechanism (5H) is not insufficient, and the outflow of the low-stage compression mechanism (5L) is not excessive.

The high-stage compression mechanism (5H) compresses the intermediate-pressure refrigerant and discharges the high-pressure refrigerant into the casing (31). This high-pressure refrigerant is supplied to the stator (4) of the motor (40).
It passes between 1) and the rotor (42) and is discharged to the main refrigerant circuit (2M). This high-pressure refrigerant circulates through the refrigerant circuit (20) as described above.

-Effect of Embodiment 1- Therefore, according to the present embodiment, the high-stage compression mechanism (5
Since the cylinder volume of H) is set at a predetermined ratio to the cylinder volume of the low-stage compression mechanism (5L), the low-stage compression mechanism (5L) and the high-stage compression mechanism (5H) operate in an optimal state. And efficient driving can be performed.

That is, since the amount of refrigerant flowing into the high-stage compression mechanism (5H) does not become insufficient, the mass flow rate of the refrigerant gas discharged from the high-stage compression mechanism (5H) is stabilized, and the efficiency is improved. Can be achieved.

Also, since the amount of refrigerant discharged from the low-stage compression mechanism (5L) does not become excessive, a predetermined intermediate-pressure refrigerant flows reliably from the gas-liquid separator (23), and the economizer effect is reduced. It can be surely demonstrated.

If the cylinder capacity of the high-stage compression mechanism (5H) is set to be more than 65% and 85% or less of the cylinder capacity of the low-stage compression mechanism (5L), the operation is performed under the general air-conditioning temperature condition. The highest efficiency can be exhibited in the device to be performed.

If the cylinder capacity of the high-stage compression mechanism (5H) is set to 45% to 65% or less of the cylinder volume of the low-stage compression mechanism (5L), the apparatus operates in cold district conditions. , The highest efficiency can be exhibited.

On the other hand, since the pressure of the intermediate-pressure refrigerant (intermediate pressure) can be maintained at the optimum intermediate pressure, the economizer effect can be maximized, and the efficiency can be greatly improved. That is, since the cooling capacity and the heating capacity can be improved, the COP can be improved.

Further, since the refrigerant is compressed in two stages, an increase in the discharge temperature of the refrigerant can be suppressed.

Further, since the rotary compressor in which the piston (61) and the blade (64) are integrated is applied, the blade (64) and the piston (61) are compared with the rolling piston type rotary compressor. Does not come into contact with Therefore, wear of the blade (64) can be suppressed.

In particular, in the high-stage compression mechanism (5H),
Although the temperature of the discharged refrigerant increases, there is no wear of the blade (64), so that the influence of friction can be more reliably suppressed.

As a result, the foreign matter due to the abrasion does not flow in the refrigerant circuit (20), and the blockage of the circuit can be reliably prevented.

[0128]

[Embodiment 2] In this embodiment, as shown in FIG. 7, the entire interior of the casing (31) is replaced with a high-pressure atmosphere (high-pressure dome) as shown in FIG. Is composed of a low-pressure atmosphere and an intermediate-pressure atmosphere.

That is, the casing (31) is provided with the partition member (3M), and the motor (40) is connected to the partition member (3M).
The lower stage compression mechanism (5L) and the higher stage compression mechanism (5H) are stored in the first closed chamber (3A) above the partition member (3A).
M) in the second closed chamber (3B) below. still,
The low-stage compression mechanism (5L) is disposed above the high-stage compression mechanism (5H).

A suction side refrigerant pipe (2r) is connected to an upper portion of the casing (31), and the first closed chamber (3A) is configured to have a low pressure atmosphere. An injection pipe (2B) is connected to the center of the casing (31), and the second closed chamber (3B) is configured to have an intermediate pressure atmosphere.

The suction passage (5) of the low-stage compression mechanism (5L)
1) communicates with the first closed chamber (3A) through a low pressure passage (56) penetrating the upper plate (6u) and the partition member (3M), and discharges the low-stage compression mechanism (5L). Passage (53)
Communicates with the second closed chamber (3B).

An intermediate passage (55) vertically passing through the upper plate (6u), the low-stage cylinder (60), and the middle plate (6m) is provided with a second closed chamber (3B) and a high-stage compression mechanism. (5H) communicates with the suction passage (52).

The discharge passage (54) of the high-stage compression mechanism (5H) communicates with the muffler (65) provided in the lower plate (6d). A high-pressure passage (57) vertically extending through the lower plate (6d), the high-stage cylinder (60), and the middle plate (6m) is connected to the muffler (65) and the discharge-side refrigerant pipe (2d). ing.

On the other hand, a sealing means (3s) is provided in a portion of the drive shaft (32) penetrating the partition member (3M). The sealing means (3s) includes a flange (3f) formed on the drive shaft (32) and a boss (3b) formed on the upper plate (6u).

The upper surface of the boss portion (3b) is in contact with the lower surface of the flange portion (3f) and the lower surface of the partition member (3M) so that the space between the first sealed chamber (3A) and the second sealed chamber (3B) is formed. Sealed. The boss (3b) and the flange (3f)
The thrust bearing of the drive shaft (32) is also used. In addition to the weight of the drive shaft (32) and the piston (61, 61), the boss (3b) is formed by the magnetic pull force of the motor (40). ).

Although not shown, a spiral pump is provided between the drive shaft (32) and the shaft hole of the upper plate (6u). The spiral pump supplies the lubricating oil supplied from the oil supply path (34) to the shaft hole of the upper plate (6u) between the boss (3b) and the flange (3f). In the present embodiment, the accumulator (25) is not provided in the main refrigerant circuit (2M).

Therefore, according to the second embodiment, the low-pressure gas refrigerant returning from the main refrigerant circuit (2M) is supplied to the first closed chamber (3M).
A), and in particular, since the main refrigerant circuit (2M) is not provided with an accumulator, the low-pressure refrigerant passes between the stator (41) and the rotor (42) of the motor (40). The liquid refrigerant evaporates, flows into the low-stage compression mechanism (5L) through the low-pressure passage (56), and is compressed.

On the other hand, since the intermediate-pressure refrigerant is supplied from the gas-liquid separator (23) to the second closed chamber (3B), the intermediate-pressure refrigerant discharged from the low-stage compression mechanism (5L) and the gas-liquid Separator (2
The intermediate-pressure refrigerant supplied from 3) joins in the second closed chamber (3B), passes through the intermediate passage (55), flows into the cylinder chamber (6s) of the high-stage compression mechanism (5H), and is compressed. You.

Thereafter, the high-pressure refrigerant discharged from the high-stage compression mechanism (5H) passes through the high-pressure passage (57), is discharged to the main refrigerant circuit (2M), and circulates in the refrigerant circuit (20).

The other structures, functions and effects such as the cylinder volume ratio of the low-stage compression mechanism (5L) and the high-stage compression mechanism (5H) are the same as those in the first embodiment.

[0141]

Third Embodiment In this embodiment, as shown in FIG. 8, the low-stage compression mechanism (5L) is constituted by a rotary compressor as in the first embodiment, while the high-stage compression mechanism (5H) is used. ) Is composed of a scroll compressor.

The high-stage compression mechanism (5
H) is configured by housing a fixed scroll (70) and a revolving scroll (71) in a casing (31). The fixed scroll (70) and the orbiting scroll (71) are provided with spiral (involute) wraps (7c, 7d) standing in front of a disk-shaped end plate (7a, 7b). The two end plates (7a, 7b) are vertically arranged with their front faces facing each other, and the two wraps (7c, 7
d) are engaged with each other.

The outer peripheral edge of the end plate (7a) of the fixed scroll (70) is fixed to the casing (31). A cylindrical scroll shaft (7e) protrudes from the center of the rear surface of the end plate (7b) of the orbiting scroll (71).
The rear side (lower side) of the head plate (7b) is a casing (31)
And is slidably mounted on a frame (72) fixed to the frame.

The upper end of the drive shaft (32) is supported by a bearing (73) fixed to a frame (72), and an eccentric part (74) is formed so as to protrude. Shaft (7e) is inserted.

The revolving scroll (71) is prevented from rotating by, for example, an Oldham ring provided between the revolving scroll (71) and the frame (72), and the rotation of the drive shaft (32) causes the axial center of the drive shaft (32) to rotate. It is configured so that only the revolving motion is performed on the fixed scroll (70) with the center as the center. Then, the compression chamber formed between the two wraps (7c, 7d) contracts while moving helically from the outside toward the center and compresses the refrigerant.

On the other hand, inside the casing (31) below the frame (72), the discharge passage (5L) of the low-stage compression mechanism (5L) is provided.
3) communicates, and the injection pipe (2B) communicates to form an intermediate pressure atmosphere, which is formed in the intermediate passage (55). The end plate (7a) of the fixed scroll (70)
The inside of the casing (31) above the discharge side refrigerant pipe (2
d) is connected to form a high-pressure atmosphere.

The outside of the two wraps (7c, 7d) is formed as a suction chamber (75), and the suction chamber (75) communicates with a suction passage (52) formed in a frame (72). It communicates with the intermediate passage (55).

In the end plate (7a) of the fixed scroll (70), a discharge passage (54) is formed in the center, and an auxiliary valve (76) is provided. The auxiliary valve (76) opens and closes the auxiliary passage (7f). When the high-pressure refrigerant that is being compressed by the fixed scroll (70) and the revolving scroll (71) reaches the discharge pressure of the high-pressure atmosphere, the auxiliary valve (76) opens. It is configured to allow only discharge to a high-pressure atmosphere.

Accordingly, the refrigerant compressed by the low-stage compression mechanism (5L) is discharged to the intermediate passage (55) in the casing (31), and after the intermediate-pressure refrigerant in the injection pipe (2B) has joined, Flows into the suction passage (52) of the side compression mechanism (5H).

On the other hand, the orbiting scroll (71) of the high-stage compression mechanism (5H) rotates eccentrically due to the rotation of the drive shaft (32), and performs only orbiting with respect to the fixed scroll (70). While being formed sequentially between the wraps (7c, 7d),
Shrink while moving toward the center.

The intermediate-pressure refrigerant flows into the compression chamber from the suction chamber (75), is compressed, and is discharged from the discharge passage (54) in principle. During the compression, when the high-pressure refrigerant is compressed to a high-pressure atmosphere, the auxiliary valve (76) opens and discharges into the high-pressure atmosphere.

As a result, the refrigerant is discharged without being over-compressed. Other configurations, functions, and effects such as the cylinder volume ratio of the low-stage compression mechanism (5L) and the high-stage compression mechanism (5H) are the same as those in the first embodiment.

[0153]

Other Embodiments The low-stage compression mechanism (5L) and the high-stage compression mechanism (5H) in each of the above embodiments have a piston (61) and a blade (64) formed integrally. Although a so-called swing type rotary compressor or scroll compressor is applied, the present invention may apply a rolling piston type rotary compressor in which a piston (61) and a blade (64) are separated.

In contrast to the third embodiment, the low-stage compression mechanism (5L) may be constituted by a scroll compressor, and the high-stage compression mechanism (5H) may be constituted by a rotary compressor.

In the first embodiment, the high-stage compression mechanism (5H) is arranged above the low-stage compression mechanism (5L). The low-stage compression mechanism (5L) may be arranged above.

In the second embodiment, the motor (40) is housed in the first closed chamber (3A), and the low-stage compression mechanism (5L) and the high-stage compression mechanism ( 5H), but the motor (40) and the high-stage compression mechanism (5H) are housed in the first closed chamber (3A), and the low-stage compression mechanism (5L) is housed in the second closed chamber (3B). ) May be stored. That is, the high-stage compression mechanism (5H) is disposed above the low-stage compression mechanism (5L), and the first closed chamber (3A) and the second closed chamber (3B) are formed by the middle plate (6m). Then, the first closed chamber (3A) is set to a high pressure atmosphere, and the second closed chamber (3B) is set to an intermediate pressure atmosphere.

In each embodiment, the air conditioner (10) capable of performing the cooling operation and the heating operation has been described. However, the present invention is directed to a cooling-only air conditioner that performs only the cooling operation and a heating device that performs only the heating operation. It may be a dedicated air conditioner.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a compressor according to a first embodiment.

FIG. 2 is a refrigerant circuit diagram showing the first embodiment.

FIG. 3 is a plan sectional view showing a low-stage compression mechanism and a high-stage compression mechanism.

FIG. 4 is a Mollier chart showing refrigerant characteristics of the refrigerant circuit of the first embodiment.

FIG. 5 is a Mollier chart showing refrigerant characteristics in consideration of compressor efficiency and the like.

FIG. 6 is a state diagram showing a relationship between pressure and volume of the compressor of the first embodiment.

FIG. 7 is a longitudinal sectional view showing a compressor according to a second embodiment.

FIG. 8 is a refrigerant circuit diagram showing Embodiment 2.

[Explanation of symbols]

 10 Air conditioner 20 Refrigerant circuit 2B Injection pipe 30 Compressor 31 Casing 40 Motor 5L Low stage compression mechanism 5H High stage compression mechanism 51, 52 Suction passage 53, 54 Discharge passage 55 Intermediate passage

Claims (4)

[Claims] A low-stage compression mechanism (5) is provided on a casing (31).
L) and the high-stage compression mechanism (5H) are housed, and the two-stage compression mechanism (5L, 5H) compresses the low-pressure fluid in two stages and discharges the high-pressure fluid. The discharge port (53) of the mechanism (5L) and the suction port (52) of the high-stage compression mechanism (5H) communicate with each other via an intermediate passage (55). The introduction pipe (2B) that introduces the intermediate pressure fluid that is intermediate with the high pressure fluid communicates, while the cylinder capacity of the high stage compression mechanism (5H) is larger than that of the low stage compression mechanism (5L). A two-stage compressor characterized by being set to 85% or less. 2. The two-stage compressor according to claim 1, wherein the low-stage compression mechanism (5L) and the high-stage compression mechanism (5H) have a capacity relative to the volume of the sillidan of the low-stage compression mechanism (5L). A two-stage compressor wherein the cylinder capacity of the high-stage compression mechanism (5H) is configured for a low compression ratio set within a range of greater than 65% and 85% or less. 3. The two-stage compressor according to claim 1, wherein the low-stage compression mechanism (5L) and the high-stage compression mechanism (5H) have a capacity with respect to the silidan volume of the low-stage compression mechanism (5L). A two-stage compressor, wherein the cylinder capacity of the high-stage compression mechanism (5H) is configured for a high compression ratio set within a range of 45% to 65%. 4. The two-stage compressor (30) according to any one of claims 1 to 3, a heat source side heat exchanger (22), a first expansion mechanism (E1), and a gas-liquid separator (30). 23) and the second expansion mechanism (E2)
And the use-side heat exchanger (24) are connected in order to form a refrigerant circuit (20) through which the refrigerant circulates, and between the two-stage compressor (30) and the gas-liquid separator (23). Is
An air conditioner, wherein an inlet pipe (2B) for supplying an intermediate-pressure refrigerant from a gas-liquid separator (23) to a two-stage compressor (30) is connected.