JP2001027460A - Refrigeration cycle system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a compressor against damage by making the compressor to suck refrigerant gas and lubricant separated in an accumulator efficiently and preventing insufficient lubrication thereby ensuring reliability of the compressor. SOLUTION: Wet refrigerant from an evaporator fed through a suction pipe 56 is subjected to gas/liquid separation and lubricant forms an upper layer while liquid refrigerant forms a lower layer at the bottom of an accumulator 55 because of the difference of specific gravity. The liquid refrigerant is heated above saturation temperature by means of a heater 60 provided on the bottom of the accumulator 55 and evaporated. It is then sucked through a delivery pipe 57 into a compressor and only lubricant stands on the bottom of the accumulator 55. Subsequently, a valve 61 in a delivery pipe 59 laid on the bottom of the accumulator 55 is opened and the lubricant is sucked therefrom into the compressor. The series of operations is controlled by detection signals from a liquid level detector 63, a refrigerant saturation temperature detector 64 and a refrigerant temperature detector 65 mounted on the accumulator 55.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an accumulator used for an air conditioner or a refrigerator.

[0002] The present invention also relates to a refrigeration cycle apparatus in which a compressor, a condenser, a decompression device, an evaporator, and an accumulator are sequentially connected by refrigerant piping.

[0003] The present invention also relates to a refrigeration cycle apparatus in which a compressor, a four-way valve, an indoor heat exchanger, a check valve, a receiver, a pressure reducing device, an outdoor heat exchanger, and an accumulator are sequentially connected by refrigerant piping.

[0004]

2. Description of the Related Art A general refrigeration cycle is shown in FIG.
The compressor (14), the condenser (15), the pressure reducer (16), the evaporator (17), and the accumulator (18) are connected in a ring shape by piping. For example, a known accumulator (18) described in JP-B-57-17187 and JP-B-62-52230 has a suction pipe (2) at an intermediate portion of a cylindrical closed vessel (1) as shown in FIG. A discharge pipe (7) is attached to the bottom. The discharge pipe (7) has one opening protruding into the cylindrical closed container (1), and the cylindrical closed container.
A small hole (8) is provided in the vicinity passing through (1).

[0005] Since the conventional accumulator is configured as described above, the mixed liquid of the lubricating oil and the refrigerant liquid collected at the bottom of the cylindrical closed container (1) is discharged from the small hole (8) through the discharge pipe.
It is sucked into (7) and sent to the compressor (14).

[0006] Generally, in a refrigeration cycle apparatus,
The accumulator is provided in front of the compressor suction side, separates the gas-liquid refrigerant into gas and liquid, prevents the compressor from inhaling the liquid refrigerant, and accumulates the compressor lubricating oil flowing with the refrigerant. It is required to return to the compressor smoothly without staying in the inside. As shown in FIG. 11, a conventional refrigeration cycle includes a compressor (51), a condenser (52), and a decompression device.
(53), an evaporator (54), and an accumulator (55) which are sequentially connected by refrigerant piping.
As shown in FIG. 12, the accumulator (55) disclosed in Japanese Patent Publication No. 4 includes a refrigerant suction pipe (56) and a refrigerant discharge pipe (57), and an oil return pipe (58) is attached to the refrigerant discharge pipe (57). The accumulator (55) further includes a heating device (60) for heating the liquid refrigerant and a detection device (63) for detecting the liquid level in the accumulator (55).

In such a conventional refrigeration cycle apparatus, when the wet refrigerant flows from the suction pipe (56),
The liquid refrigerant accumulates at the bottom of the accumulator (55), and the discharge pipe
From (57), only the gas refrigerant flows out. accumulator
Lubricating oil also accumulates at the bottom of (55), dissolves with the liquid refrigerant, and a mixed fluid of the lubricating oil and liquid refrigerant is sucked into the discharge pipe (57) from the oil return pipe (58) to lubricate the sliding parts of the compressor. It is carried out.
Then, when the liquid level in the accumulator (55) rises above a certain value, this is detected by the level detector (63),
The liquid refrigerant is heated by the heating device (60), becomes a gas refrigerant, and is sucked into the compressor through the discharge pipe (57).

Another conventional refrigeration cycle is as follows:
As shown in FIG. 13, a compressor (71), a four-way valve (72), an indoor heat exchanger (73), a check valve (74a) (74b), a receiver (75), a pressure reducing device (76a) (76b) , Outdoor heat exchanger (77), accumulator (78)
Are sequentially and functionally connected by a refrigerant pipe.

In such a conventional refrigeration cycle apparatus, lubricating oil necessary for normal operation of the compressor (71) is supplied from an accumulator (78). The lubricating oil is present in the accumulator (78) in a state of being dissolved with the refrigerant, accumulates as a mixed fluid with the liquid refrigerant at the bottom of the accumulator, returns to the refrigerating cycle through an oil return hole provided in the discharge pipe of the accumulator, and is sent to the compressor. The lubrication of the sliding part of the compressor is performed.

[0010]

A conventional accumulator as shown in FIG. 11 is provided in front of the suction side of a compressor to prevent refrigerant liquid from flowing into the compressor.
It is required that the lubricating oil flows smoothly, but if a lubricating oil having a specific gravity smaller than the refrigerant liquid is used, the moist refrigerant gas will flow through the suction pipe (2) into the cylindrical closed vessel (1). The liquid mixture collected at the bottom of the cylindrical closed container (1) when it flows into the small closed hole (8) is divided into lubricating oil at the top and refrigerant liquid at the bottom.
, The lubricating oil cannot return to the compressor, and the compressor may be damaged due to wear or the like.

An accumulator as shown in FIG. 12 constituting a conventional refrigeration cycle apparatus as shown in FIG.
In (55), the mixture of liquid refrigerant and lubricating oil stored at the bottom of the accumulator (55) has a layer rich in lubricating oil in the upper layer and a layer rich in liquid refrigerant in the lower layer due to the specific gravity of the two. Depending on the vertical position of the oil return pipe (58), only liquid refrigerant is sucked from the oil return pipe (58), lubricating oil does not return to the compressor, and wear may cause damage to the compressor due to wear. was there. In the above description, the accumulator (55) is based on the assumption that the refrigerant and the lubricating oil are mutually soluble.If the refrigerant does not dissolve in the lubricating oil at all, the refrigerant and the lubricating oil are completely separated in the accumulator (55). The lubricating oil will accumulate in the upper layer of the liquid refrigerant due to the specific gravity of both.
As long as there is no lubricating oil at the position of the oil return pipe (58), the lubricating oil does not return to the compressor, and the lubricating oil stays in the accumulator (55), possibly causing damage to the compressor.

Further, in the accumulator constituting the conventional refrigeration cycle apparatus as shown in FIG. 13, the lubricating oil does not return to the compressor in the same manner as described above, and there is a possibility that the compressor may be damaged.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. Even when lubricating oil and refrigerant are compatible with each other or when refrigerant is not completely dissolved in lubricating oil, lubricating oil is stored in the accumulator. Provided are an accumulator and a refrigeration cycle device that ensure refrigerant reliability and prevent compressor damage by preventing refrigerant gas and lubricating oil from being efficiently sucked into a compressor without stagnation and preventing lubrication failure. The purpose is to do so.

[0014]

According to a first aspect of the present invention, there is provided a refrigeration cycle apparatus in which a compressor, a condenser, a decompression device, an evaporator, and an accumulator are sequentially connected by a refrigerant pipe, and an adjustment valve is provided at the bottom of the accumulator. In a refrigeration cycle device connected to a discharge pipe for injecting lubricating oil to the compressor suction side via a heating device for heating the bottom of the accumulator,
A liquid level detector for detecting a liquid level of the accumulator, a refrigerant temperature detector for detecting a refrigerant temperature in the accumulator, and a refrigerant saturation temperature detector for detecting a refrigerant saturation temperature in the accumulator; Operate the heating device in response to detection of a predetermined level or more by the surface level detector, and terminate the operation of the heating device when the detected temperature of the refrigerant temperature detector becomes higher than the detected temperature of the refrigerant saturation temperature detector. The main configuration is that the regulating valve is opened for a certain period of time.

According to a second aspect of the present invention, there is provided a refrigeration cycle apparatus comprising, in addition to the configuration of the first aspect, a liquid storage device between a condenser and a pressure reducing device constituting the refrigeration cycle.

A refrigeration cycle apparatus according to a third aspect of the present invention is a refrigeration cycle apparatus in which a compressor, a condenser, a receiver, a first decompression device, an evaporator, and an accumulator are sequentially connected by refrigerant piping. Penetrate,
And a discharge pipe connected to the compressor suction side, a second pressure reducing device provided between the receiver of the discharge pipe and the compressor suction side, and a discharge-side pipe of the second pressure reducing device and the condenser And heat exchange between a pipe connecting the evaporator and the receiver, and adjusting the opening degree of the second decompression device until the merging from the receiver to the compressor suction side via the second decompression device. The main configuration is to be a gas refrigerant.

A refrigeration cycle apparatus according to a fourth aspect of the present invention is the refrigeration cycle apparatus according to the third aspect, wherein a temperature-type expansion valve is used as the second pressure reducing device, and a temperature-sensitive cylinder is provided at a discharge-side pipe portion of the temperature-type expansion valve. Is attached.

According to a fifth aspect of the present invention, there is provided a refrigeration cycle apparatus according to the third aspect, wherein an electronic expansion valve is used as the second pressure reducing device, and a pipe immediately after heat exchange with a discharge-side pipe portion of the electronic expansion valve. The main configuration is that a temperature sensor is attached to the electronic expansion valve and the opening degree of the electronic expansion valve is adjusted so that the detected temperature difference becomes a predetermined value or more.

A refrigeration cycle apparatus according to a sixth aspect of the present invention is the refrigeration cycle apparatus according to any one of the first to fifth aspects, which mainly uses a refrigeration cycle lubricating oil which does not dissolve in the liquid refrigerant.

[0020]

According to a first aspect of the present invention, there is provided a refrigeration cycle apparatus including a liquid level detector, a refrigerant saturation temperature detector, and a refrigerant temperature detector, and operating a heating device and a valve based on detection signals from these detectors. Thereby, the lubricating oil can be reliably returned to the compressor.

A refrigeration cycle apparatus according to a second aspect of the present invention adjusts the amount of refrigerant by storing excess refrigerant in a liquid storage device in addition to the operation according to the first aspect of the present invention.

In the refrigeration cycle apparatus according to the third aspect of the present invention, a discharge pipe is provided from the receiver via the second pressure reducing device to the compressor suction side, and the discharge pipe is connected to the discharge side pipe of the second pressure reducing device. Heat exchange is performed between a pipe connecting the condenser and the evaporator to the receiver, and by adjusting an opening degree of the second decompression device, the compressor is suctioned from the receiver via the second decompression device. A part of the refrigerant is vaporized and supplied to the compressor together with the lubricating oil by being made into a gas refrigerant before the refrigerant is joined.

A refrigeration cycle apparatus according to a fourth aspect of the present invention makes the operation according to the third aspect of the present invention more appropriate by operating a thermal expansion valve.

The refrigeration cycle apparatus according to the fifth aspect of the present invention makes the operation according to the third aspect of the present invention more appropriate by operating the electronic expansion valve using a temperature sensor.

According to the refrigeration cycle apparatus according to the sixth aspect of the present invention, in the refrigeration cycle apparatus according to the first to fifth aspects of the present invention, the lubricating oil for the refrigeration cycle that does not dissolve the liquid refrigerant is returned to the compressor together with the vaporized refrigerant. is there.

[0026]

[Embodiment 1] An embodiment of the present invention will be described below with reference to the drawings. The same parts as those of the conventional example shown in FIG. FIG. 1 is a diagram showing a refrigerant circuit of a refrigeration cycle according to the present invention, in which a compressor (51), a condenser (52), a pressure reducing device (53), an evaporator (54), and an accumulator (55) are sequentially connected by refrigerant piping. A circuit having a pipe (59) connected to the compressor suction side at the bottom of the accumulator (55) is formed. FIG. 2 is an explanatory diagram showing the inside of the accumulator according to the present invention. The accumulator (55) includes a refrigerant suction pipe (56) and a refrigerant discharge pipe (57), a heating device (60) provided at the bottom thereof, and a discharge pipe (59) connected to the compressor suction side. I have. The discharge pipe (59) is provided with a valve (61) and the accumulator (5
5) is provided with a liquid level detector (63), a refrigerant saturation temperature detector (64), and a refrigerant temperature detector (65).

Next, the operation of the accumulator in FIG. 2 will be described. When the wet refrigerant flows from the suction pipe (56) of the accumulator (55) during the refrigeration cycle operation, gas-liquid separation is performed in the accumulator (55), and gas refrigerant flows out from the discharge pipe (57). The liquid refrigerant and the lubricating oil accumulate at the bottom of the accumulator (55). When the liquid refrigerant and the lubricating oil are mixed, a layer rich in the lubricating oil accumulates in the upper layer and a layer enriched in the liquid refrigerant accumulates in the lower layer due to the specific gravity of the two. Further, when the liquid refrigerant and the lubricating oil do not dissolve, the lubricating oil separates and accumulates in the lower layer due to the specific gravity of the two. At this time, by using a heating device (60) provided at the bottom of the accumulator (55) to sufficiently heat the refrigerant to the refrigerant saturation temperature or more, the liquid refrigerant remaining in the lower layer evaporates and gasifies, and the discharge pipe ( 57) from the compressor
The liquid refrigerant does not exist in the accumulator (55), and only the lubricating oil accumulates at the bottom of the accumulator (55). Thereafter, by opening the valve (61) on the discharge pipe (59) connected to the compressor suction side provided at the bottom of the accumulator (55), the lubricating oil accumulated at the bottom of the accumulator (55) is sucked into the compressor. To go. If this series of operations is controlled by detection signals from the liquid level detector (63), the refrigerant saturation temperature detector (64), and the refrigerant temperature detector (65) provided in the accumulator (55), the accumulator (55) It is possible to control the return of the lubricating oil accumulated in the compressor to the compressor at a time, avoiding the suction of the liquid refrigerant and the shortage of lubricating oil that may cause compressor damage.
It is possible to ensure the reliability of the compressor.

In FIG. 2, the accumulator (55)
Although the example in which the heating device (60) is accommodated in the inside is shown, the heating device (60) may be provided on the outer bottom of the accumulator (55), and may be configured to heat from the outside. In addition, this heating device (60)
The same effect can be obtained by using an electric heater or a discharge gas from a compressor as a heat source.

The above series of operations will be described with reference to the flowchart of FIG. After a lapse of a fixed time from the start of operation of the refrigeration cycle device, the accumulator (55)
Starts liquid level detection in the inside. Thereafter, the detection of the liquid level does not need to be performed continuously, but may be performed every certain sampling time. When the liquid level is higher than the set value, by turning on the heating device (60), the accumulator (55) is turned on.
The liquid refrigerant accumulated inside is heated to promote gasification of the refrigerant. Thereafter, the detection of the refrigerant saturation temperature and the refrigerant temperature, which are changed by the pressure in the accumulator (55), is started by the detectors (64) and (65). Thereafter, when the refrigerant temperature becomes higher than the refrigerant saturation temperature, that is, when it becomes superheated vapor, it is determined that gasification of the liquid refrigerant has been completed, and the heating device is turned off.
I do. In this state, since the lubricating oil is accumulated at the bottom of the accumulator (55), the lubricating oil is sucked into the compressor by opening the valve (61). After a certain period of time, a series of operations for closing the valve (61) and returning the lubricating oil to the compressor ends. The time interval for detecting the liquid level and the time interval for opening and closing the valve (61) differ depending on the capacity of the accumulator and the heating capacity of the heating device. do it. If the valve (61) is an electromagnetic valve, the valve (61)
The opening / closing timing can be electrically controlled by the detection signal from the liquid level detector (63), and a system with better controllability can be provided. In this way, by forcibly sucking the lubricating oil accumulated in the accumulator (55) into the compressor, the lubricating oil is accumulated in the accumulator (55) even when the liquid refrigerant and the lubricating oil do not melt. This makes it possible to reliably return the lubricating oil to the compressor without intrusion, thereby avoiding the suction of the liquid refrigerant and the shortage of the lubricating oil which may cause damage to the compressor, and ensuring the reliability of the compressor.

Embodiment 2 FIG. FIG. 4 is a diagram illustrating a refrigerant circuit of a refrigeration cycle according to Embodiment 2 of the present invention. Also in this embodiment, the same reference numerals are given to the same or corresponding portions as those in the conventional example shown in FIG. 11 and the first embodiment shown in FIG. FIG. 4 and FIG. 1 showing the first embodiment.
The difference between this is that a liquid storage device (62) is provided between the condenser (52) and the pressure reducing device (53), and the operation of returning the refrigerant and lubricating oil stored in the accumulator to the compressor is described. Is
This is exactly the same as the first embodiment. The accumulator (55) is required to have a function of storing excess refrigerant in addition to a gas-liquid separation function and an oil return function. In this embodiment, as in the first embodiment, the heating device (60) provided at the bottom of the accumulator (55) is turned on to return the lubricating oil from the bottom of the accumulator (55) to the compressor through the pipe (59). At this time, the excess liquid refrigerant accumulated in the accumulator (55) turns on the heating device (60) provided in the accumulator (55),
Although it is gasified and returns during the refrigeration cycle, in this state, the refrigeration cycle is in a state of excess refrigerant. Therefore, by storing this excess refrigerant in the liquid storage device (62),
The refrigeration cycle is operated with an appropriate amount of refrigerant, and lubricating oil can be reliably returned to the compressor without accumulating lubricating oil in the accumulator (55). In addition, the shortage of lubricating oil can be avoided and the reliability of the compressor can be ensured.

Embodiment 3 FIG. An embodiment of the present invention will be described below with reference to the drawings. FIG. 5 is a diagram showing a refrigerant circuit of a refrigeration cycle according to the present invention, in which a compressor (71), a four-way valve (7
2), indoor heat exchanger (73), check valves (74a) (74b), receiver (7
5), the first decompression devices (76a) (76b), the outdoor heat exchanger (77), and the accumulator (78) are connected by refrigerant piping, penetrate the lower part of the receiver (75), and are connected to the compressor suction side And a second pressure reducing device between the receiver (75) and the compressor suction side.
(79), and further provided from the receiver (75) to the second decompression device (7).
On the discharge pipe connected to the compressor suction side via 9), the indoor heat exchanger is connected between the second pressure reducing device and the compressor suction side.
(73) and a circuit provided with a heat exchanger (80a) (80b) for exchanging heat with a pipe leading from the outdoor heat exchanger (77) to the receiver (75).

The operation of the refrigeration cycle apparatus shown in FIG. 5 will be described below. Receiver (75) and indoor heat exchanger (73)
The state of the refrigerant flowing through the pipe connecting the outdoor heat exchanger (77) is a high-pressure liquid, and the state does not change even in the cooling or heating operation. Therefore, the state will be described below under the heating operation. The refrigerant discharged from the indoor heat exchanger (73) passes through the check valve (74a), and the high-pressure refrigerant flows into the receiver (75) together with the lubricating oil. The receiver is connected to the compressor suction side via a refrigerant pipe via a decompression device (79), and a part of the fluid is supplied to this pipe according to the difference between the pressure at the receiver (75) and the pressure at the compressor suction side. Inhaled. This fluid is a mixture of the lubricating oil and the refrigerant when the lubricating oil and the refrigerant are soluble, and a fluid when the lubricating oil and the refrigerant are not soluble. When the refrigerant in the sucked fluid passes through the pressure reducing device (79),
The pressure is reduced and the adiabatic expansion is performed, and a part of the refrigerant is vaporized to become a gas-liquid mixed refrigerant and sent to the suction side of the compressor (71) together with the lubricating oil. At this time, the refrigerant is partially vaporized by the pressure reducing device (79) on the pipe and is in a gas-liquid mixed state, but the heat exchangers (80a) (80b) on the pipe absorb heat and all It evaporates and becomes gaseous and returns to the compressor together with the lubricating oil.

As described above, even when the lubricating oil and the refrigerant do not mix with each other, or when a part of the lubricating oil stays in the accumulator (78), the discharge pipe connected from the receiver (75) to the compressor suction side can be used. Through the heat exchange, all the refrigerant is vaporized and lubricating oil is sent, smoothing the supply of lubricating oil to the compressor, avoiding damage to the compressor due to insufficient lubricating oil, and ensuring compressor reliability. can do.

Embodiment 4 FIG. FIG. 6 is a diagram showing a refrigerant circuit of a refrigeration cycle according to Embodiment 4 of the present invention. The same parts as those in the third embodiment are denoted by the same reference numerals, and the description thereof will not be repeated. FIG.
5 showing Embodiment 3 and Embodiment 3 is different from FIG. 5 in that a temperature expansion valve (83) is provided instead of the pressure reducing device (79), and the discharge side of the heat exchanger (80b) is controlled to control the temperature expansion valve. Pipe temperature tube (8
4).

The difference between this embodiment and the third embodiment in operation is that the temperature of the refrigerant sucked into the compressor (71) together with the lubricating oil is controlled by the temperature type expansion valve (83). By controlling the temperature of the refrigerant sucked into the compressor (71), the pressure difference between the refrigerant and the refrigerant sucked into the compressor (71) through the accumulator (78) is reduced, and the suction pressure is reduced. It is possible to prevent a sharp drop and eliminate shortage of lubricating oil, thereby ensuring the reliability of the compressor.

Embodiment 5 FIG. FIG. 7 is a diagram showing a refrigerant circuit of a refrigeration cycle according to Embodiment 4 of the present invention. The difference between FIG. 7 and FIG. 6 showing the fourth embodiment is that the temperature type expansion valve (83)
In place of this, an electronic expansion valve (81) is provided, and further, in order to control the electronic expansion valve (81), a discharge pipe in which the electronic expansion valve (81) is present and a discharge side of the heat exchanger (80b) are provided. Temperature sensor on piping
(82a) and (82b) are provided respectively.

The difference between this embodiment and the fourth embodiment in operation is that the degree of superheat of the refrigerant sucked into the compressor (71) together with the lubricating oil is controlled by the electronic expansion valve (81). FIG. 8 is a flowchart showing the control of the degree of superheat of the refrigerant. In controlling the degree of superheat of the refrigerant, the degree of superheat of the refrigerant is calculated from the temperature difference between the temperature sensors (82a) and (82b).
(Approx. ° C) by controlling the throttle of the electronic expansion valve (81), further reducing the pressure difference between the refrigerant and the refrigerant drawn into the compressor (71) through the accumulator (78), Of the compressor can be prevented, the shortage of lubricating oil can be eliminated, and the reliability of the compressor can be ensured.

[0038]

Since the present invention is configured as described above, it has the following effects.

According to the first aspect of the present invention, a compressor, a condenser, a decompression device, an evaporator, and an accumulator are sequentially connected by a refrigerant pipe, and lubricating oil is supplied to the compressor suction side via an adjusting valve at the bottom of the accumulator. In a refrigeration cycle device connected to a discharge pipe for injecting a liquid, a heating device for heating the bottom of the accumulator, a liquid level detector for detecting a liquid level of the accumulator, and a refrigerant temperature detector for detecting a refrigerant temperature in the accumulator And a refrigerant saturation temperature detector for detecting a refrigerant saturation temperature in the accumulator is provided, and the heating device is operated in accordance with detection of a predetermined level or more of the liquid level detector, and the detected temperature of the refrigerant temperature detector is increased. When the temperature becomes higher than the temperature detected by the refrigerant saturation temperature detector, the operation of the heating device is terminated, and the adjustment valve is turned off. Since the lubricating oil is opened for a long time, lubricating oil can be reliably returned to the compressor without accumulating lubricating oil in the accumulator, avoiding suction of liquid refrigerant and insufficient lubricating oil that could cause compressor damage. Thus, the reliability of the compressor can be ensured.

According to the invention of claim 2, according to claim 1,
In addition to the invention of the present invention, since the liquid storage device is provided between the condenser and the pressure reducing device, even if the refrigeration cycle has an excess refrigerant,
By storing excess refrigerant in the liquid storage device, the refrigeration cycle is operated with an appropriate amount of refrigerant, and the same effects as those of the sixteenth aspect can be obtained.

According to the third aspect of the present invention, a compressor,
In a refrigeration cycle apparatus in which a condenser, a receiver, a first decompression device, an evaporator, and an accumulator are sequentially connected by a refrigerant pipe, a discharge pipe penetrating a lower portion of the receiver and connected to a compressor suction side is provided. A second decompression device is provided between the receiver and the compressor suction side of the pipe, and heat exchange is performed between the pipe on the discharge side of the second decompression apparatus and the pipe connecting the condenser and the evaporator to the receiver. The main configuration is that the opening degree of the second decompression device is adjusted to be a gas refrigerant before the second decompression device joins the compressor suction side via the second decompression device through the second decompression device. Therefore, even if the lubricating oil stays in the accumulator, the lubricating oil can be recovered by this receiver, so that the lubricating oil can always be returned to the compressor, which is one of the causes of the compressor damage. This eliminates the need for lubricating oil and prevents the compressor from being damaged due to the inhalation of liquid refrigerant. Performance can be improved.

According to the fourth aspect of the present invention, a temperature-type expansion valve is used as the second pressure reducing device, and a temperature-sensitive cylinder is attached to a discharge-side pipe portion of the temperature-type expansion valve. Since the throttle of the control valve is controlled by the temperature difference, the degree of superheat of the refrigerant sucked into the compressor is made appropriate, and a sharp decrease in the pressure of the refrigerant sucked into the compressor is prevented. Damage to the compressor due to lack of lubricating oil can be prevented, and the reliability of the compressor can be improved.

According to the fifth aspect of the present invention, an electronic expansion valve is used as the second pressure reducing device, and a temperature sensor is attached to a discharge side pipe portion of the electronic expansion valve and a pipe immediately after heat exchange. The opening degree of the electronic expansion valve is adjusted so that the detected temperature difference becomes equal to or more than a predetermined value, so that the degree of superheat of the refrigerant drawn into the compressor is made appropriate, and the refrigerant drawn into the compressor is adjusted. Of the compressor can be prevented, and the compressor can be prevented from being damaged due to lack of lubricating oil, so that the reliability of the compressor can be improved.

According to the invention of claim 6, in each of the above-mentioned inventions, lubricating oil for a refrigeration cycle that does not dissolve in the liquid refrigerant is used, so that inexpensive liquid refrigerant or lubricating oil can be used.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of a refrigeration cycle apparatus showing Embodiment 1 of the present invention.

FIG. 2 is a sectional view of an accumulator of the refrigeration cycle apparatus according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing an operation according to the first embodiment of the present invention.

FIG. 4 is a refrigerant circuit diagram of a refrigeration cycle apparatus according to a second embodiment of the present invention.

FIG. 5 is a refrigerant circuit diagram of a refrigeration cycle apparatus showing a third embodiment of the present invention.

FIG. 6 is a refrigerant circuit diagram of a refrigeration cycle apparatus showing a fourth embodiment of the present invention.

FIG. 7 is a refrigerant circuit diagram of a refrigeration cycle apparatus showing Embodiment 5 of the present invention.

FIG. 8 is a flowchart showing control of the degree of superheat of the refrigerant in Embodiment 5 of the present invention.

FIG. 9 is a refrigerant circuit diagram of a general refrigeration cycle device.

FIG. 10 is a sectional view of a conventional accumulator.

FIG. 11 is a refrigerant circuit diagram of a conventional refrigeration cycle device.

FIG. 12 is a cross-sectional view of an accumulator in a conventional refrigeration cycle device.

FIG. 13 is a refrigerant circuit diagram of a conventional refrigeration cycle device.

[Explanation of symbols]

Reference Signs List 1 cylindrical closed container, 2 suction pipe, 7 discharge pipe, 8 small hole, 14 compressor, 15 condenser, 16 pressure reducer, 17
Evaporator, 18 accumulator, 51 compressor, 52
Condenser, 53 decompression device, 54 evaporator, 55 accumulator, 56 suction pipe, 57 discharge pipe, 58 oil return pipe, 59 discharge pipe, 60 heating device, 61 valve, 62
Reservoir, 63 Liquid level detector, 64 Refrigerant saturation temperature detector, 65 Refrigerant temperature detector, 71 Compressor,
72 four-way valve, 73 indoor heat exchanger, 74a check valve,
74b check valve, 75 receiver, 76a pressure reducing device,
76b pressure reducing device, 77 outdoor heat exchanger, 78 accumulator, 79 pressure reducing device, 80a heat exchanger, 80b
Heat exchanger, 81 electronic expansion valve (control valve), 82a temperature sensor, 82b temperature sensor, 83 temperature type expansion valve (control valve), 84 pipe temperature tube.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takayuki Yoshida 3-181, Oka, Shizuoka-shi Mitsubishi Electric Corporation Living Environment Engineering Management Center (72) Inventor Masao Nagano 3-181, Oga, Shizuoka-shi Mitsubishi (72) Inventor Atsushi Edayoshi 3-18-1, Oka, Shizuoka-shi Mitsubishi Electric Corporation Living Environment Engineering Management Center (72) Inventor Masaru Konishi 2-chome Otemachi, Chiyoda-ku, Tokyo 6-2 Nihon Kentei Co., Ltd. (72) Inventor Toshihide Koda 8-1-1, Tsukaguchi Honcho, Amagasaki City Mitsubishi Electric Corporation Central Research Laboratory (72) Inventor Yoshihiro Sumita 8-1-1, Tsukaguchi Honcho Amagasaki City 1 Mitsubishi Electric Corporation Central Research Laboratory (72) Inventor Takashi Okazaki Amagasaki 8-1-1, Ichizukaguchi Honcho Mitsubishi Electric Corporation Central Research Laboratory (72) Inventor Yoshihisa Kito 3-181-1, Oka, Shizuoka-shi Mitsubishi Electric Corporation Shizuoka Works (72) Inventor Osamu Morimoto Ichide Wakayama No. 6-5-66, Mitsubishi Electric Corporation Wakayama Manufacturing Co., Ltd. (72) Inventor Tomohiko Kasai No. 6-5-66 Tehira, Wakayama City Mitsubishi Electric Wakayama Manufacturing Co., Ltd.

Claims (6)

[Claims] 1. A compressor, a condenser, a decompression device, an evaporator, and an accumulator are sequentially connected by a refrigerant pipe, and a discharge pipe for injecting lubricating oil to a compressor suction side is connected to a bottom of the accumulator via an adjustment valve. In the refrigeration cycle apparatus, a heating device for heating the bottom of the accumulator, a liquid level detector for detecting a liquid level of the accumulator, a refrigerant temperature detector for detecting a refrigerant temperature in the accumulator, and a refrigerant in the accumulator A refrigerant saturation temperature detector for detecting a saturation temperature is provided, and the heating device is operated in response to detection of a predetermined level or more of the liquid level detector, and a detection temperature of the refrigerant temperature detector is set to a value of the refrigerant saturation temperature detector. When the temperature becomes higher than the detected temperature, the operation of the heating device is terminated, and the regulating valve is opened for a predetermined time. A refrigeration cycle device characterized by the above-mentioned. 2. A liquid storage device is provided between a condenser and a pressure reducing device constituting a refrigeration cycle.
A refrigeration cycle apparatus as described in the above. 3. A refrigeration cycle apparatus in which a compressor, a condenser, a receiver, a first decompression device, an evaporator, and an accumulator are sequentially connected by refrigerant piping, and penetrates a lower portion of the receiver and is connected to a compressor suction side. A discharge pipe is provided between the receiver and the compressor suction side of the discharge pipe.
Is provided, and the pipe on the discharge side of the second decompressor and the pipe connecting the condenser and the evaporator to the receiver are subjected to heat exchange, and the opening degree of the second decompressor is adjusted. A refrigeration cycle apparatus wherein the refrigerant is converted into a gas refrigerant before it joins the compressor suction side via the second pressure reducing device from the receiver. 4. The refrigeration cycle apparatus according to claim 3, wherein a temperature-type expansion valve is used as the second pressure reducing device, and a temperature-sensitive cylinder is attached to a discharge-side pipe portion of the temperature-type expansion valve. 5. An electronic expansion valve is used as a second pressure reducing device, and a temperature sensor is attached to a discharge side pipe portion of the electronic expansion valve and a pipe immediately after heat exchange, and a temperature difference detected by the temperature sensor is set to a predetermined value or more. 4. The refrigeration cycle apparatus according to claim 3, wherein an opening of the electronic expansion valve is adjusted so as to be adjusted. 6. The refrigeration cycle apparatus according to claim 1, wherein lubricating oil for a refrigeration cycle that does not dissolve in a liquid refrigerant is used.