JPH05133368A - Two-stage compression refrigerator provided with check valve device - Google Patents

Abstract

PURPOSE:To improve a two-stage compression/two-stage expansion refrigerating cycle by preventing refrigerating gas from its reverse flow from a communication path between low/high-step compressing elements to a gas-liquid separator arranged between a condenser and an evaporator, in a two-stage compression refrigerator of using a two-stage compressor. CONSTITUTION:A two-stage refrigerating compressor 1 having a two-stage compressing mechanism of connecting a delivery side of a low-stage compressing element 7 to a suction side of a high-stage compressing element 9 in series through a communication path, condenser 13, first expanding device 15, gas- liquid separator 17, second expanding device 19 and an evaporator 21 are successively connected by pipes. A refrigerant injection passage 72 of connecting the halfway of the communication path to the gas-liquid separator of the two- stage compressor is constituted to arrange a check valve device, which permits an inflow of fluid to only the communication path from a gas-liquid separator 2, on the halfway of this refrigerant injection passage 72.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improving the durability of a refrigeration cycle having a two-stage compression function by preventing backflow in the refrigeration system.

[0002]

2. Description of the Related Art In recent years, in the field of refrigeration equipment, as part of securing low-temperature heat sources and high-temperature heat sources, research into practical use of refrigerant compressors suitable for high compression ratio operation has been active.

In particular, various multi-stage rotary compressors have been proposed as a measure for reducing the pressure difference between the compression chamber and the suction chamber to reduce the amount of leakage gas during compression and improve the compression efficiency. There is.

Specifically, a two-stage compression refrigeration cycle system diagram in which a low rig piston type rotary two-stage compressor and the same compressor are connected has been proposed in the configurations of FIGS. -72205).

In the same figure, a compression motor 1005 is connected to the upper part of a closed container 1003 and a rotary shaft 1005c of the drive motor 1005 is connected to the lower part of the closed container 1003. Is a high-pressure compression mechanism 1
009), an oil sump is arranged in the lower part, and the low pressure compression mechanism 100
7. The back surface of the vane 1007c (1009c) that divides each cylinder of the high-pressure compression mechanism 1009 into the suction chamber and the compression chamber communicates with the internal space of the closed container 1003.
The back pressure biasing force to 007c (1009c) is formed by the reaction force of the spring device and the pressure inside the sealed container 1003.

The refrigerant gas discharged from the low pressure compression mechanism 1007 is
It is connected to the external gas-liquid separator 1017 via the discharge pipe 1007e, and is again closed via the communication pipe 1009d '.
It flows into the internal space of 003 to cool the drive motor 1005.

The discharged refrigerant gas re-flowing into the closed container 1003 sucks the lubricating oil at the bottom of the closed container 1003 when passing through the suction pipe 1009d provided with the oil absorption pipe 1023, and is introduced into the high pressure compression mechanism 1009. Is used for cooling the sliding surface and sealing the compression chamber gap.

The discharged refrigerant gas recompressed by the high-pressure compression mechanism 1009 is discharged through the discharge pipe 1009e to the outside condenser 1
013, the first expansion valve 1015, gas-liquid separator 1
017, the second expansion valve 1019, the evaporator 1021, and the low pressure compression mechanism 1 again through the suction pipe 1007d.
Return to 007.

Although not shown in the embodiments, as described in the description, in order to improve the large torque fluctuation at the time of compression, which is a drawback of the low rig piston rotary compressor, the crankshaft eccentric direction of the rotary shaft 1005c is improved. By 180 degrees, and vanes (1007c, 1009c) of both compression mechanisms (low pressure compression element mechanism 1007, high pressure compression element mechanism 1009)
The mounting direction is shifted by 75 to 80 degrees between the high-stage side and the low-stage side. As a result, measures have been proposed to reduce the fluctuation compared to the rotary one-stage compressor.

A two-stage compression refrigeration cycle is constructed by such a component arrangement, and is devised so that the internal space of the closed container 1003 is maintained at an intermediate pressure between the condensation pressure and the evaporation pressure of the refrigerant.

Further, as described in Japanese Patent Application Laid-Open No. 60-128990, in a heat pump water heater and a heat pump type air conditioner, it is better to use a two-stage compression refrigeration cycle. It is known that the efficiency of the refrigeration cycle is improved as compared with the case of using, and in particular, in the case of a heat pump water heater having a large temperature difference, the compressor discharge temperature can be lowered, so that overheating of the compressor can be prevented. There is.

[0012]

However, utilizing this well-known technique, the intermediate passage between the discharge side of the low-stage compression element and the suction side of the high-stage compression element of the two-stage compressor, and the two-stage expansion refrigeration When the two-stage expansion refrigeration cycle using the two-stage compressor is operated by connecting the downstream side of the gas-liquid separator in the cycle by piping, the following trouble may occur.

That is, as is well known, the suction cylinder volume of the high pressure compression element mechanism 1009 in the two-stage compressor is set to be equivalent to the volume of the refrigerant gas discharged from the low pressure compression element mechanism 1007. In the discharge stroke transient period, excess and deficiency occur between the volume of the refrigerant gas discharged from the low pressure compression element mechanism 1007 and the suction cylinder volume of the high pressure compression element mechanism 1009, and as a result, the two compression elements communicate with each other. Pressure pulsation occurs in the intermediate passage, and the discharge pressure in the low-pressure compression element mechanism 1007 increases instantaneously, and the suction pressure in the high-pressure compression element mechanism 1009 decreases instantaneously, and the compression ratio fluctuates. As a result, when the pressure on the discharge side of the high-pressure compression element mechanism 1009 is low as in the initial stage of starting the two-stage compressor, the refrigerant gas in the intermediate passage is separated from the gas-liquid separator 10.
17 and the normal refrigeration cycle cannot be performed. Therefore, as a countermeasure against this, the intermediate passage and the gas-liquid separator 1017 are used.
There is also a method in which a stop valve type on-off valve is provided between and, and after the compressor is started, an appropriate time is delayed and the valve is opened after the pressure of the gas-liquid separator 1017 has risen. Two-stage compression / two-stage expansion refrigeration due to complicated control of the refrigeration cycle piping system due to the need for means for detecting the pressure in each passage and means for opening / closing the stop valve based on the pressure detection. There is a problem that the cost of the device is increased and the device is increased in size.

Further, during the hot water supply operation and the air conditioning heating operation in the winter in the two-stage compression / two-stage expansion refrigeration cycle, when the surface of the heat exchanger on the heat absorber side is frosted, the pipe to the heat absorber side and the radiator side. Immediately after starting the defrosting operation by switching the piping to the solenoid valve etc., a large amount of high-pressure liquid refrigerant on the radiator side flows into the suction side of the two-stage compressor, causing liquid compression in the low-pressure compression element mechanism. , The pressure in the intermediate passage rises abnormally. On the other hand, since the pressure on the gas-liquid separator 1017 side drops sharply by switching to the defrosting operation,
The pressure in the intermediate passage becomes higher than that in the gas-liquid separator 1017, and the refrigerant flows backward from the intermediate passage of the two-stage compressor to the side of the gas-liquid separator 1017 in the same manner as in the above case, causing damage to the refrigeration cycle piping system control device. There was a problem of inviting.

In view of the above-mentioned conventional problems, the present invention is a two-stage compression two-stage expansion refrigeration cycle using a two-stage compressor, and a gas-liquid arranged between a condenser and an evaporator at the initial stage of starting the compressor. It is an object of the present invention to improve the efficiency of a two-stage compression refrigeration system by preventing the refrigerant gas from flowing back into the separator from the communication path between the low-stage compression element and the high-stage compression element.

Further, according to the present invention, in a two-stage compression two-stage expansion refrigeration cycle using a two-stage compressor, a simple means for backflow from the discharge side of the bottom stage compression element to the gas-liquid separator at the initial stage of compressor startup or the like. The present invention aims to reduce the cost, reduce the reliability, and reduce the size of the two-stage compression refrigeration system.

[0017]

In order to solve the above problems, the present invention provides a two-stage compression mechanism in which the discharge side of a low-stage compression element and the suction side of a high-stage compression element are connected in series via a communication passage. The two-stage refrigerant compressor, the condenser, the first expansion device, the gas-liquid separator, the second expansion device, and the evaporator, which are included, are sequentially pipe-connected,
A check valve that forms a refrigerant injection passage that connects the gas-liquid separator to the middle of the communication passage of the two-stage compressor, and allows fluid to flow only from the gas-liquid separator to the communication passage in the middle of the refrigerant injection passage. The device is arranged.

Further, according to the present invention, the valve body of the check valve device is configured to contact the end face of the compression section connecting pipe forming the introduction path from the gas-liquid separator to perform the check function.

[0019]

The operation of the above means is as follows.

According to the present invention, the gas pressure of the communication passage between the low-stage compression element and the high-stage compression element is such that the gas pressure is between the condenser and the evaporator of the two-stage compression two-stage expansion refrigeration cycle at the initial stage of compressor startup. When the fluid pressure is higher than that of the provided gas-liquid separator, the refrigerant injection passage is closed, and the gas in the communication passage is sucked and compressed by the high-stage compression element without flowing back to the gas-liquid separator side. After that, it is discharged to the condenser of the compressor external piping system, and with the passage of time after the compressor is started, the pressure inside the gas-liquid separator rises above the gas pressure in the communication passage, the refrigerant injection passage is opened, and the gas-liquid The non-evaporated refrigerant from the separator flows into the communication passage, merges with the discharge gas from the low-stage compression element, is sent to the high-stage compression element, and cools the high-stage compression element.

Further, according to the present invention, the gas pressure in the communication passage between the low-stage compression element and the high-stage compression element is 2 at the initial stage of compressor startup.
When the fluid pressure is higher than the fluid pressure of the gas-liquid separator provided between the condenser and the evaporator of the two-stage compression two-stage expansion refrigeration cycle,
The pressure difference causes the valve body of the check valve device to move to the side of the end face of the compressor connection pipe to close the end face of the compressor connection pipe, shut off the refrigerant injection passage, and shut off the refrigerant from the communication passage to the gas-liquid separator. Backflow is prevented. When the pressure in the gas-liquid separator rises above the gas pressure in the communication passage with the passage of time after the compressor is started, the valve element of the check valve device separates from the end surface of the compressor connection pipe due to the pressure difference, and refrigerant injection occurs. The passage opens, joins the discharge fluid from the low-stage compression element, and is sent to the high-stage compression element to cool the high-stage compression element.

[0022]

EXAMPLE A rolling piston type rotary two-stage refrigerant compressor according to a first embodiment of the present invention and a two-stage compression two-stage expansion refrigeration cycle piping system using the same will be described below.
This will be described with reference to FIGS.

FIG. 1 is a rolling piston type rotary two-stage compressor 1 equipped with an accumulator 2, a condenser 13,
FIG. 2 shows a piping system of a two-stage compression two-stage expansion refrigeration cycle in which a first expansion valve 15, a gas-liquid separator 17, a second expansion valve 19 and an evaporator 21 are sequentially connected, and FIG. 2 is a rolling piston type rotary two-stage compression. A cross section of the machine 1 and FIG. 3 show details of essential parts of the two-stage compression mechanism.

An electric motor 5 is arranged in an electric motor chamber 8 in an upper space of the closed container 3, and a two-stage compression mechanism 4 is arranged below the electric motor chamber 8. An outer peripheral portion and a bottom portion thereof are constituted as an oil sump 35.

The stator 5a of the electric motor 5 is shrink-fitted and fixed to the inner wall of the closed container 3. The two-stage compression mechanism 4 is composed of an upper high-stage compression element 9, a lower low-stage compression element 7, and a flat plate-shaped middle plate 36 arranged between both compression elements (7, 9). The discharge cover A37 of the element 7 and the outer peripheral portion of the middle plate 36 are welded and fixed to the inner wall of the closed container 3 at several places (not shown).

The cylinder volume of the high-stage compression element 9 is set to about 45 to 65% of the cylinder volume of the low-stage compression element 7.

An upper bearing member 11 attached to the upper side surface of the second cylinder block 9a of the high-stage compression element 9 and a lower bearing member 12 attached to the lower side surface of the first cylinder block 7a of the low-stage compression element 7. Drive shaft 6 supported by and
Is connected and fixed to the rotor 5b of the electric motor 5.

The first crankshaft 6a and the second crankshaft 6b of the drive shaft 6 are arranged so that their eccentric directions are offset from each other by 180 degrees.

Reference numerals 7b and 9b denote the first crankshaft 6 of the drive shaft 6.
a, the first piston and the second piston mounted on the second crankshaft 6b, 38 and 39 are the first piston 7b and the second piston
A vane that abuts on the outer peripheral surface of the piston 9b and divides the cylinders of the low-stage compression element 7 and the high-stage compression element 9 into a suction chamber and a compression chamber, and 40 and 41 urge the rear surfaces of the vanes 38 and 39. It is a coil spring.

The rear end of the coil spring 41 of the high-stage compression element 9 is supported by the inner wall of the closed container 3, but the rear end of the coil spring 40 of the low-stage compression element 7 is hermetically mounted on the first cylinder block 7a. It is supported by the closed cap 42.

Back chamber B4 of the vane 39 of the high-stage compression element 9
3 is open to the oil sump 35, but the back chamber A44 of the vane 38 of the low-stage compression element 7 is sealed off at its end by the cap 42 and is cut off from the oil sump 35.

The discharge cover A37 of the low-stage compression element 7 is attached to the first cylinder block 7a together with the lower bearing member 12 to form a low-stage discharge chamber 45, and the bottom thereof is a discharge chamber oil sump 46.

The discharge chamber oil sump 46 is fixed to the discharge cover A37 and is partitioned from the upper space of the low-stage discharge chamber 45 by a partition plate 48 having a plurality of small holes 47, and the bottom portion thereof is the discharge cover A37 and the lower bearing member. The back chamber A44 of the vane 38 communicates with an oil return passage 49 including an oil return hole A49a and an oil return hole B49b.

The discharge cover B50 formed by damping steel plate is
The high-stage discharge chamber 51 is formed by being arranged so as to surround the outer circumference of the upper bearing member 11.

The muffling chamber 52, which is recessed at the end of the rotor 5b of the electric motor 5, has an annular passage 53 between it and the projecting portion 50a of the discharge cover B50 that surrounds the outer periphery of the projecting portion 11a of the upper bearing member 11. Communicating with the high-stage discharge chamber 51, and the inner surface of the end ring 5c of the rotor 5b and the discharge cover B50.
To the inner space of the closed container 3 via an annular passage 54 between the protruding portion 50a and

The low-stage discharge chamber 45 and the suction chamber 56 of the high-stage compression element 9 have a gas passage A5 provided in the lower bearing member 12.
5a, a gas passage B55b provided in the first cylinder block 7a, and a gas passage C55c provided in the intermediate plate 36, which communicates with each other.

The bypass passage 57 branched from the middle of the communication passage 55 is provided in the second cylinder block 9a of the high-stage compression element 9.
And a bypass passage A57 provided in the upper bearing member 11
a and a bypass passage B57b, the downstream side of which is opened to the high-stage discharge chamber 51.

The bypass passage A57a is provided with a bypass valve device 58 consisting of a thin steel plate valve body 58a (not shown in FIG. 4) having a cutout portion on its outer peripheral portion and a coil spring 58b. The valve device 58 allows the fluid flow only from the communication passage 55 to the high-stage discharge chamber 51.

The coil spring 58b has a shape memory alloy characteristic in which its spring constant increases when the temperature of the coil spring 58b itself rises, and the urging force to the valve body 58a increases.

Gas passage B5 forming part of the communication passage 55
5b communicates with the downstream side of the gas-liquid separator 17 via a communication pipe 59, and forms a refrigerant injection passage 72.

The communication pipe 59 is the first cylinder block 7a.
The outer periphery of the connecting portion is sealed with an O-ring 66, and a valve body 60 having a shape similar to that of FIG. 4 is arranged between the end portion and the gas passage B55b to form a check valve device 71. There is.

The check valve device 71 is configured to allow the fluid to flow only from the gas-liquid separator 17 into the gas passage B55b.

The middle plate 36 is provided with an oil injection passage 61 having a throttle part in the middle of the passage. The upstream side thereof is the oil sump 35 and the downstream side thereof is the rear chamber A of the vane 38.
44 and the compression chamber of the high-stage compression element 9 are provided so as to intermittently communicate with each other.

The downstream passage A61a of the oil injection passage 61 and the rear chamber A44 are opened when the vane 38 is advanced to the piston 7b side by a stroke of approximately half or more,
It opens at the sliding end surface of the vane 44 to shut off at other times.

The downstream passage B61b of the oil injection passage 61 and the compression chamber of the high-stage compression element 9 start to open when the vane 39 advances to the piston 7b side to the stroke of approximately one third, and approximately three minutes. When the stroke 1 is retreated, the sliding end surface of the piston 9b opens to a position where interruption is started (see FIG. 5).

The shaft core of the drive shaft 6 has a penetrating shaft hole 62.
Is provided, and the pump device 63 is attached to the lower part thereof.

Helical oil grooves 64, 64 are formed on the outer peripheral surface of the drive shaft 5 supported by the upper bearing member 11 and the lower bearing member 12.
a is provided, the upstream side of the spiral oil groove 64 communicates with the downstream side of the pump device 63 via a radial oil hole branched from the shaft hole 62, and the downstream side of the spiral oil groove 64 has a silencing chamber 52. Not open to.

A downstream side of the accumulator 2 communicates with a suction chamber (not shown) of the low-stage compression element 7, and a discharge pipe 7e is provided above the closed container 3.

A second expansion valve 19 is provided at the bottom of the gas-liquid separator 17.
Is connected to a liquid pipe 65, the outer surface of the body of the gas-liquid separator 17 is coated with a polyethylene film, and the polyethylene foam material 67 is heated and foamed to about 5 mm.
Has been heat-insulated.

FIG. 6 shows an opened state of the bypass passage 57 immediately after the compressor is started cold, a state in which the valve body 60 closes the end of the communication pipe 59, a downstream side passage 61a of the oil injection passage 61 and the rear chamber A44. A state in which the vane 38 blocks the space between and is shown.

Next, the structure of the check valve device of the rolling piston type rotary two-stage refrigerant compressor of the second embodiment of the present invention will be described with reference to FIG.

The inner diameter of the suction pipe of the accumulator used in the conventional one-stage compressor is made about 1.5 times larger than that of the suction pipe of the accumulator to follow the suction action of the compressor. The gas pressure causes a pulsation phenomenon, and the gas whose pressure rises cyclically flows into the suction chamber and is compressed in that state, thereby increasing the suction efficiency). The downstream side of the accumulator 202 is connected to the suction side of the low stage compression element 207, as in the case of the first embodiment.

Low-stage discharge chamber 245 of low-stage compression element 207
Is formed by the discharge cover A237 and the first cylinder block 207a attached to the first cylinder block 207a so as to surround the lower bearing member 212 that supports the drive shaft 6, and the internal volume thereof is the first embodiment. It is smaller than the example configuration.

The high-stage compression element 209 is the low-stage compression element 20.
The suction / compression action starts at a phase delay of about 60 to 80 degrees with respect to the suction / compression timing of No. 7, and the low-stage discharge chamber 245
It is arranged to reduce the compression power in the low-stage compression element 207 by suppressing the excessive pressure rise in the inside.

The upper part of the low-stage discharge chamber 245 communicating with the back chamber A244 is connected to the suction side of the high-stage compression element 209 via the communication passage 255, and the communication passage 255 is formed on the way.
The second accumulator 202b connected to is connected at its upstream side to a gas-liquid separator (not shown) similar to that in the case of the first embodiment, and at the downstream end of the connecting portion, the first accumulator 202b is connected. A valve body 206 similar to the example is mounted.

A coil spring 270 for closing the open end of the connecting portion from the gas-liquid separator 17 is biased to the valve body 206, and the spring constant of the coil spring 270 decreases as the temperature of the coil spring 270 increases and the coil spring 270 moves toward the valve body 206. It has a shape memory characteristic that reduces the biasing force of. The end face of the communication pipe 59 and the valve body 20
The check valve device 271 is constituted by 6 and the coil spring 270.

The other structure is the same as that of the first embodiment, and the description thereof is omitted. The operation of the two-stage compressor configured as above and its refrigeration cycle will be described.

In FIGS. 1 to 6, when the drive shaft 6 is rotationally driven by the motor 5, the low-stage compression element 7 always starts sucking and the refrigerant gas from the accumulator 2 flows into the suction chamber of the low-stage compression element 7. To do. While the volume of the low-stage suction chamber increases as the crank angle of the drive shaft 6 advances, the compression action in the low-stage compression chamber also progresses at the same time, and the compressed refrigerant gas pressure gradually increases.

The compressed refrigerant gas is supplied to the lower bearing member 1 when the low-stage crank angle advances by about 170 degrees after the start of the suction action.
The liquid is discharged into the low-stage discharge chamber 45 from a discharge port (not shown) provided in No. 2.

The refrigerant gas discharged to the low-stage discharge chamber 45 is
Through the oil return passage 49 composed of the oil return hole A49a and the oil return hole B49b, the lubricating oil that accumulates at the bottom of the discharge chamber oil sump 46 flows back into the back chamber A44, and the back face of the vane 38 is brought to the first piston 7b. Back pressure is applied to the side of.

Immediately after starting, the refrigerant gas discharged to the low-stage discharge chamber 45 is delivered to the suction chamber 56 of the high-stage compression element 9 via the communication passage 55 composed of the gas passage A55a, the gas passage B55b, and the gas passage C55c. To be done.

60 to 80 from the start of inhalation of the low-stage compression element 7
After a delay, the high-stage compression element 9 also starts the suction / compression action.

Immediately after starting, the low-stage discharge chamber 45 and the communication passage 5
The refrigerant gas of 5 is higher than the condenser 13 and the gas-liquid separator 17 which are connected to the internal space of the closed container 3 and the rolling piston type rotary two-stage compressor 1 by piping.

Therefore, as shown in FIG.
The pressure difference between the discharged refrigerant gas passing through 5 and the gas-liquid separator 17 causes the valve body 60 to move to close the end of the connecting pipe 59 of the gas-liquid separator 17, and the refrigerant injection passage 72 to close. Refrigerant gas in the communication passage 55 is prevented from flowing back to the gas-liquid separator 17.

Further, the pressure of the refrigerant gas in the communication passage 55 is higher than the pressure in the high-stage discharge chamber 51 communicating with the internal space of the closed container 3, and the valve body 58a of the bypass valve device 58 has the coil spring 58.
It moves toward the coil spring 58b against the urging force of b to open the bypass passage 57, and a part of the refrigerant gas passing through the communication passage 55 flows out to the high-stage discharge chamber 51 and flows into the suction chamber 56. The pressure drops. As a result, the vane 39 of the high-stage compression element 9 that depends on the biasing force of only the coil spring 41 causes a jumping phenomenon that occurs when the refrigerant gas whose pressure has risen suddenly flows into the suction chamber 56 and suddenly retracts. Instead, the second piston 9b retreats following the movement of the outer peripheral surface of the second piston 9b, and a smooth light load compression action is started without producing a collision noise between the vane 39 and the second piston 9b or leakage of compressed gas.

Since the suction / compression action of the high-stage compression element 9 starts 60 to 80 degrees after the suction / compression action of the low-stage compression element 7 starts, the low-stage compression chamber 45 to the low-stage discharge chamber 45 starts. Between the volume of the refrigerant gas discharged to the high-pressure compression element 9 and the volume of the suction chamber of the high-stage compression element 9, and the excess / deficiency amount is the drive shaft 6
Changes with the crank angle of. As a result, there is a crank angle range in which the amount of the refrigerant gas discharged to the low-stage discharge chamber 45 is insufficient and a surplus crank angle range, so that the refrigerant gas in the low-stage discharge chamber 45 and the communication passage 55 is pressurized. Pulsation occurs. This pressure pulsation tends to occur more intensely as the rotational speed of the drive shaft 6 increases.

The discharged refrigerant gas discharged into the high-stage discharge chamber 51 flows into the muffling chamber 52 through the annular passage 53, and thereafter,
It is delivered to the internal space of the closed container 3 via the annular passage 54.

With the lapse of time after the cold start of the compressor, the pressures of the electric motor chamber 8, the condenser 13 and the gas-liquid separator 17 communicating with the electric motor chamber 8 rise, and the bypass valve device 5 in the bypass passage 57 is increased.
The valve body 58a of No. 8 is biased by the coil spring 58b whose spring constant is increased by the gas pressure and temperature rise of the high-stage discharge chamber 51 to close the bypass passage 57 and close the end of the communication pipe 59. The body 60 moves toward the communication passage 55 to open the refrigerant injection passage 72 between the gas-liquid separator 17 and the communication passage 55.

The lubricating oil in the oil sump 35, which is acted upon by the discharge pressure, together with the coil spring 41 of the high-stage compression element 9 and the vanes 3.
A small amount of gas flows into the suction chamber 56 and the compression chamber through the sliding surface gap while urging the back surface of 9 and backing the sliding surface of the vane 39. Further, the lubricating oil is decompressed through the downstream passage B61b of the oil injection passage 61 having the throttle passage portion and is intermittently supplied to the compression chamber to seal the oil film in the compression chamber gap and lubricate the sliding surface of the second piston 39. Be offered to.

The lubricating oil in the oil sump 35 is the downstream passage A61a of the oil injection passage 61 having the throttle passage portion.
After the pressure is reduced to a level equivalent to the discharge pressure of the low-stage compression element 7 via the vane 38, the vane 38 of the low-stage compression element 7 moves to the first piston 7
During the time point of advancing to about 1/3 to the side of b and retreating to about 1/3 again, the opening of the downstream passage A61a to the back chamber A44 is opened and flows into the back chamber A44. ..

The lubricating oil that has flowed into the rear chamber A44 lubricates the sliding surface of the vane 38, and also flows into the low-stage discharge chamber 45 through the oil return hole B49b and the oil return hole A49a and mixes with the discharged refrigerant gas. And flows into the suction chamber 56 of the high-stage compression element 9. The lubricating oil that has flowed into the suction chamber 56 of the high-stage compression element 9 merges with the lubricating oil that has flowed in via the back chamber B43 and the downstream passage 61b to provide sealing of the compression chamber gap and lubrication and cooling of the sliding surface. To be done.

The lubricating oil in the oil sump 35 is supplied to the shaft hole 62 by the viscous pump action of the spiral oil groove 64 provided on the surface of the drive shaft 6 and the pump device 62 provided at the lower end of the drive shaft 6. Oil is supplied to the bearing surfaces of the lower bearing member 12 and the upper bearing member 11 that support the drive shaft 6 and the inner surfaces of the first piston 7b and the second piston 9b via the radial holes 69. The lubricating oil supplied to the spiral oil groove 64a is discharged from the upper end of the bearing of the upper bearing member 11 to the muffling chamber 52 by the viscous pump action, and the two-stage compressed high-pressure discharge gas discharged from the high-stage discharge chamber 51. After mixing, it is discharged into the electric motor chamber 8 through the annular passage 54.

The discharged refrigerant gas from which the lubricating oil has been separated in the electric motor chamber 8 is sent to the refrigeration cycle outside the compressor via the discharge pipe 7e.

The non-evaporated refrigerant, which has been decompressed via the condenser 13 and the first expansion valve 15 and expanded to the discharge pressure of the low-stage compression element 7, flows into the gas-liquid separator 17 and becomes gas. It is separated into liquid and liquefied refrigerant is collected at the bottom of the gas-liquid separator 17.

The non-evaporated refrigerant gas in the upper space inside the gas-liquid separator 17 is connected to the communication pipe 5 that opens to the upper space inside the gas-liquid separator 17.
After flowing into the communication passage 55 in the rolling piston type rotary two-stage compressor 1 via 9 and joining the discharge refrigerant gas of the low-stage compression element 7 to lower the low-stage discharge refrigerant gas temperature,
It flows into the suction chamber 56 of the high-stage compression element 9.

The second-stage compression discharge refrigerant gas of the high-stage compression element 9 sucks the non-evaporated refrigerant gas of the gas-liquid separator 17 to suppress an abnormal temperature rise. As a result, the reduction of the sliding portion clearance is reduced, and the abnormal temperature rise of the electric motor 5 is suppressed to reduce the compressor input.

On the other hand, the liquefied refrigerant collected at the bottom of the gas-liquid separator 17 is passed through the liquid pipe 65 to the second expansion valve 19 and the evaporator 2.
After the second expansion and heat absorption through 1 in sequence, it returns to the accumulator 2 again.

Since the refrigerant in the gas-liquid separator 17 is insulated and soundproofed by the polyethylene foam member surrounding the outer periphery of the body of the gas-liquid separator 17, when the refrigerant flows into the gas-liquid separator 17. The collision sound between the refrigerant and the inner wall of the gas-liquid separator is prevented from propagating to the outside, and the refrigerant does not absorb much heat.

When the frost forms on the surface of the heat exchanger on the heat absorber side during the hot water supply operation or the air conditioning heating operation in the winter in the two-stage compression / two-stage expansion refrigeration cycle, the pipe to the heat absorber side and the radiator side Immediately after the defrosting operation is started by switching the piping to the low pressure compression element 7 for a while immediately after the defrosting operation is started, the high pressure liquid refrigerant on the radiator side flows into the suction side of the second stage refrigerant compressor 1. The liquid is compressed in the compression chamber, and the pressure in the communication passage 55 rises abnormally. On the other hand, since the pressure in the gas-liquid separator 17 and the electric motor chamber 8 drops sharply by switching to the defrosting operation, the pressure in the communication passage 55 becomes higher than that in the gas-liquid separator 17 and the electric motor chamber 8, and the communication passage 55
Although the refrigerant tries to flow back from the gas-liquid separator 17 to the gas-liquid separator 17, the valve body 60 moves to the side of the communication pipe 59, closes the end of the communication pipe 59, and closes the refrigerant injection passage 72, as in the case described above. At the same time, the bypass valve device 58 operates to open the bypass passage 57, the refrigerant pressure in the communication passage 55 decreases, and the compression load on the high-stage compression element 9 is reduced.

Next, the operation of the second embodiment will be described with reference to FIG. The refrigerant gas that has flowed into the first accumulator 202 by the operation of the two-stage compressor has its periodic pressure pulsation suppressed, flows into the suction chamber of the low-stage compression element 207 via the suction pipe 202a, and is compressed. , Are sequentially delivered to the suction side of the high-stage compression element 209. Since the supercharging action of the first accumulator 202 is suppressed, the suction gas volume to the low-stage compression element 207 per one rotation of the drive shaft 6 does not change much even if the compressor operating speed changes, The low-stage discharge gas is delivered at a substantially constant rate with respect to the cylinder volume of the high-stage compression element 209. As a result, the low-stage discharge gas pressure is kept substantially constant without abnormal pressure rise even when the compressor operating speed fluctuates, and overcompression of the low-stage compression element 207 in the compression chamber is reduced.

The non-evaporated refrigerant that has flowed into the second accumulator 202b from the gas-liquid separator (not shown) is the check valve 2
The gas flows into the suction side of the high-stage compression element 209 together with the low-stage discharge gas via 06.

On the other hand, the low-stage discharge chamber 245 having a small internal volume
The low-stage discharge refrigerant gas discharged to the diffuser diffuses without separating the lubricating oil and entrains the lubricating oil that has flowed into the adjacent back chamber A244 from the oil reservoir 35 through the oil injection passage 261 and slides in the back chamber A244. After lubricating the surface, it is delivered to the high-stage compression element 209.

After the compressor is stopped, the temperature of the coil spring 270 is lowered and the spring constant thereof is increased, and the valve body 58a is moved to the second accumulator 202b side to block the inflow passage thereof, and the compressor is stopped. Second accumulator 202
The liquid refrigerant is prevented from flowing into the communication passage 255 via b.

The other operations are similar to those of the first embodiment, and the description thereof will be omitted.

As described above, according to the above embodiment, the low-stage discharge chamber 45 of the low-stage compression element 7 and the suction chamber 5 of the high-stage compression element 9 are provided.
6, a two-stage refrigerant compressor 1 having a two-stage compression mechanism connected in series via a communication passage 55, a condenser 13, and a first expansion device 1.
5, the gas-liquid separator 17, the second expansion device 19, and the evaporator 21 are sequentially connected by piping, and the communication passage 5 of the two-stage refrigerant compressor 1 is connected.
5, a refrigerant injection passage 72 that connects the gas-liquid separator 17 to the middle thereof is formed, and the refrigerant injection passage 7 is formed.
By arranging the check valve device 71 that allows the fluid to flow only from the gas-liquid separator 17 to the communication passage 55 in the middle of 2,
Low-stage compression element 7 and high-stage compression element 9 such as the initial stage of compressor startup
When the refrigerant gas pressure of the communication passage 55 between the and is higher than the refrigerant pressure of the gas-liquid separator 17 provided between the condenser 13 and the evaporator 21 of the two-stage compression two-stage expansion refrigeration cycle, The refrigerant injection passage is closed to prevent the refrigerant gas in the communication passage 55 from flowing backward to the gas-liquid separator 17 side to prevent the liquid refrigerant in the gas-liquid separator 17 from flowing out, and also to the low-stage compression element 7 By configuring the normal refrigeration cycle in which the refrigerant gas compressed in step 1 is compressed by the high-stage compression element 9 and then sent to the condenser 13, the start-up of the refrigeration cycle is accelerated, and the refrigerant in the gas-liquid separator 17 has a predetermined pressure. When it exceeds, the refrigerant injection into the two-stage refrigerant compressor 1 can be automatically started, and the startup of the highly efficient two-stage compression and two-stage expansion refrigeration cycle device can be accelerated.

Further, by preventing the refrigerant from flowing back through the refrigeration cycle piping system, unnecessary movement of the lubricating oil and the liquid refrigerant is prevented, and the failure and damage of each component device constituting the refrigeration cycle piping system are prevented. can do.

Further, according to the above embodiment, the check valve device 71
Since the valve body 60 is configured to abut the end face of the communication pipe 59 forming the introduction path from the gas-liquid separator 17 to perform the check function, the check valve device is small in size and low in cost with simple means. 71 can be configured, and the reliability and size of the two-stage compression refrigeration system can be improved.

Although the rolling piston type rotary two-stage compressor has been described in the above embodiment, the present invention is also applied to other rotary two-stage compressors, reciprocating two-stage compressors, scroll two-stage compressors and the like. The same action and effect can be expected with the configuration in which the example diagram is applied and developed.

In the above embodiment, the lubricating oil under the action of the high-stage discharge gas pressure is collected in the closed container. However, due to the size of the closed container and the oil separation ability,
A lubricating oil passage may be configured to collect the lubricating oil in an oil separation device on the discharge side provided outside the compressor and introduce the lubricating oil into the inside of the compressor.

[0090]

As is apparent from the above embodiments, the present invention has a two-stage compression mechanism in which the discharge side of the low-stage compression element and the suction side of the high-stage compression element are connected in series via a communication passage. Refrigerant compressor, condenser, first expansion device, gas-liquid separator, second
The expansion device and the evaporator are sequentially connected by piping, and a refrigerant injection passage that connects the middle of the communication passage of the two-stage refrigerant compressor and the gas-liquid separator is formed, and the gas-liquid separator is formed in the middle of the refrigerant injection passage. By arranging the check valve device that allows the fluid to flow into only the communication passage, the refrigerant gas pressure in the communication passage between the low-stage compression element and the high-stage compression element is compressed by the two-stage compression at the initial stage of compressor startup. When the refrigerant pressure of the gas-liquid separator provided between the condenser and the evaporator of the stage expansion refrigeration cycle is higher than that, the refrigerant injection passage is closed, and the refrigerant gas in the communication passage is To prevent the liquid refrigerant in the gas-liquid separator from flowing out,
The refrigerant gas compressed by the low-stage compression element is compressed by the high-stage compression element and then sent to the condenser to form a normal refrigeration cycle, which accelerates the start-up of the refrigeration cycle and causes the refrigerant in the gas-liquid separator to reach a predetermined pressure. When it exceeds, the refrigerant injection into the two-stage refrigerant compressor can be automatically started, and the startup of the highly efficient two-stage compression two-stage expansion refrigeration cycle device can be accelerated.

Further, by preventing the refrigerant from flowing back through the refrigeration cycle piping system, it is possible to prevent unnecessary movement of the lubricating oil and the liquid refrigerant, and to prevent the failure and damage of each component equipment constituting the refrigeration cycle piping system. can do.

Further, according to the present invention, the discharge side of the low-stage compression element and the suction side of the high-stage compression element are connected in series via a communication passage.
A two-stage refrigerant compressor having a two-stage compression mechanism, a condenser, a first expansion device, a gas-liquid separator, a second expansion device, and an evaporator are sequentially connected by piping, and the middle of the communication passage of the two-stage refrigerant compressor Constitutes a refrigerant injection passage communicating with the liquid separator,
A check valve device that allows fluid to flow only from the gas-liquid separator into the communication passage is arranged in the middle of the refrigerant injection passage, and the valve body of the check valve device forms an introduction passage from the gas-liquid separator. Since it is configured to come into contact with the end face of the compression section connecting pipe to perform the check function, a small-sized and low-cost check valve device can be configured with simple means, and the reliability of the two-stage compression refrigeration system can be improved. And miniaturization can be achieved.

[Brief description of drawings]

FIG. 1 is a piping system diagram of a two-stage compression refrigeration cycle using a two-stage refrigerant compressor according to the first embodiment of the present invention.

FIG. 2 is a vertical sectional view of the compressor.

FIG. 3 is a sectional view of a main part of compression in the compressor.

FIG. 4 is an external view of a bypass valve used in the compressor.

5 is a partial plan view taken along the line AA in FIG.

FIG. 6 is a sectional view of the main part of the compression showing the operating states of the bypass valve device and the check valve device in the compressor.

FIG. 7 is a view showing a second embodiment of the present invention, which is provided with a check valve device;
Cross-sectional view of the main part of compression of a three-stage refrigerant compressor

FIG. 8 is a piping system diagram of a two-stage compression refrigeration cycle using a conventional two-stage refrigerant compressor.

FIG. 9 is an explanatory plan view of a compression mechanism in the compressor.

FIG. 10 is a detailed cross-sectional view of a lubricating device in the compressor.

[Explanation of symbols]

 3 Airtight container 5 Electric motor 7 Low-stage compression element 8 Electric motor room 9 High-stage compression element 13 Condenser 15 First expansion valve 17 Gas-liquid separator 19 Second expansion valve 21 Evaporator 55 Communication passage 57 Bypass passage 58 Bypass valve device 58a Valve body 58b Coil spring 59 Communication pipe 60 Valve body 72 Refrigerant injection passage 206 Check valve 270 Coil spring 271 Check valve device

Claims (2)

[Claims] 1. A two-stage refrigerant compressor, a condenser, and a first expansion device having a two-stage compression mechanism in which a discharge side of a low-stage compression element and a suction side of a high-stage compression element are connected in series via a communication passage. , The gas-liquid separator, the second expansion device, and the evaporator are sequentially connected by piping,
A refrigerant injection passage that connects the middle of the communication passage of the two-stage refrigerant compressor and the gas-liquid separator is formed, and liquid flows only from the gas-liquid separator into the communication passage in the middle of the refrigerant injection passage. A two-stage compression refrigeration system equipped with a check valve device that allows 2. The check valve device according to claim 1, wherein the valve body of the check valve device comes into contact with the end face of the compression section connecting pipe forming an introduction path from the gas-liquid separator to perform a check action. A two-stage compression refrigeration system equipped.