JPH06265223A - Refrigeration cycle device - Google Patents

Abstract

PURPOSE:To provide a refrigeration cycle device in which when an inside part of a compressor shows a negative pressure due to a certain condition, a cooling operation is carried out at once to prevented its over-heated state and the compressor is positively protected and its reliability in operation is attained. CONSTITUTION:There is provided a refrigeration cycle in which a compressor K, a condensor 30, a capillary tube 32 acting a pressure reducing device and an evaporator 33 are communicated with each other through a refrigerant pipe. A pressure sensor 36 is arranged at a location where a lower pressure in the refrigeration cycle occurs. A liquid injection circuit 37 branched from a refrigerant pipe Pa between an outputting side of the condensor 30 and the capillary tube 32 during the refrigeration cycle and directly communicating with a mechanism of the compressor is connected and the liquid injection circuit is provided with a solenoid opening or closing valve 35 connected to the pressure sensor 36 and released when the pressure sensor 36 detects a negative pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration cycle apparatus, and more particularly to improvement of a protective structure for a compressor.

[0002]

2. Description of the Related Art For example, a refrigeration cycle apparatus which constitutes an air conditioner includes a refrigeration cycle in which a compressor, a condenser, a decompression device, and an evaporator are sequentially connected via a refrigerant pipe.

The above-mentioned compressor has a very low motion noise as compared with an ordinary rotary compressor, and a suction type compressor, a discharge valve, etc. are unnecessary and the number of parts is small, and the scroll type compressor has good compression performance. Is often used.

The compression mechanism portion of this scroll compressor causes the spiral blade portion of the fixed scroll blade and the spiral blade portion of the orbiting scroll blade to mesh with each other, and these blade portions and the end plate portion of each scroll blade. To form a compressed space.

The orbiting scroll vanes are caused to orbit with respect to the fixed scroll vanes so that the refrigerant gas, which is the gas to be compressed, is sucked in from the outside of the compression space, gradually moved to the center, and compressed and discharged. ing.

[0006]

By the way, an air conditioner is composed of an indoor unit arranged in an air-conditioned room and an outdoor unit arranged outdoors, and the refrigeration cycle equipment is separately housed in each unit. To be done. Then, at the time of installation at the site, each unit is communicatively connected via a refrigerant pipe.

At the time of factory shipment, the refrigerant is sealed in at least one unit side, and after the piping connection at the site, the refrigerant sealing is released and the other unit is electrically connected.

However, for some reason, the cycle test operation may be started without forgetting to release the sealed refrigerant.

Alternatively, from the viewpoint of current global environmental problems, there is a case where a problematic refrigerant gas is temporarily recovered from the apparatus and replaced with a problem-free refrigerant gas. Gas recovery is called pump down, and is performed while the valve on the discharge side of the refrigerant is closed and connected to the recovery device, and the compressor is operating.

In any case, the inside of the hermetically sealed case forming the compressor is likely to be negative pressure. The effect of this is that the scroll blades in the compression mechanism become overheated, each blade thermally expands, and the tip edge contacts the facing end plate portion to cause friction, which may eventually lead to a burning accident. is there.

Such a state is not necessarily limited to the scroll type compressor, and occurs in, for example, a rotary type compressor, but the scroll type compressor is apt to have a remarkable thermal effect due to its structure. .

The present invention has been made in view of the above circumstances, and an object thereof is to immediately perform cooling to reach an overheated state when a negative pressure is generated in the compressor under some conditions. Provided is a refrigerating cycle device which surely protects a compressor and improves reliability.

[0013]

In order to satisfy the above object, the present invention provides a refrigeration cycle in which a compressor, a condenser, a decompression device, and an evaporator are connected to each other through a refrigerant pipe. In the device, a pressure sensor is provided at a low pressure portion in the refrigeration cycle, and a liquid injection circuit that branches from the refrigerant pipe between the condenser outlet side and the pressure reducing device in the refrigeration cycle and directly communicates with the compression mechanism portion of the compressor. And a liquid injection circuit provided with an on-off valve that opens when the pressure sensor detects a negative pressure.

[0014]

According to this structure, when the pressure sensor detects a negative pressure, the opening / closing valve is opened, and the liquid refrigerant discharged from the condenser is introduced into the compression mechanism section of the compressor via the liquid injection circuit. inject.

Therefore, the inside of the compressor is cooled by the liquid refrigerant, so that the compressor does not reach an overheated state and accidents such as burning damage are reliably prevented.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows a scroll type compressor K used in the refrigeration cycle apparatus.

In the figure, reference numeral 1 denotes a closed case, and a support frame 2 is provided in the closed case 1, and a rotary shaft 3 is rotatably supported. A scroll compression mechanism section 4 described later is provided on the upper portion of the rotary shaft 3, and a stator 5 is provided on the lower portion.
An electric motor unit 7 including a rotor 6 and a rotor 6 is provided.

The scroll compression mechanism section 4 includes a fixed scroll blade 8 mounted and fixed to the support frame 2, an orbiting scroll blade 9 pivotally supported by an eccentric portion 3a at the upper end of the rotary shaft 3, and the fixed scroll blade 8. And a valve cover 11 that surrounds the discharge-side space on the side and forms a high-pressure discharge chamber 10 inside.

Both the fixed scroll vane 8 and the orbiting scroll vane 9 have end plates 12 and 13 and the end plate 1.
Spiral blades 14 and 15 provided integrally with the blades 2 and 13
Composed of and. The wing portions 14 and 15 are meshed with each other, and a compression chamber S which is a space portion surrounded by the end plate portions 12 and 13 is formed.

A discharge port 16 is provided through the center of the end plate portion 12 of the fixed scroll vane 8 and communicates with the high pressure discharge chamber 10.

Further, a concave portion 17 is formed in an annular shape around the discharge port 16 in the fixed scroll vane end plate portion 12, and this portion and the compression chamber S are communicated with each other by a plurality of injection holes 18.

The concave portion 17 is provided between the upper end surface of the end plate portion 12 and the flange portion of the valve cover 11, and is the partition plate 1.
It is closed by 9 to form a closed space. This recess 1
An end portion of a communication hole 20 that is provided so as to penetrate from the outer peripheral surface of the end plate portion 12 is open at 7, and an injection pipe 21 to be described later is connected thereto.

On the other hand, a discharge refrigerant pipe 22 which communicates with a condenser (not shown) is connected to the valve cover 11 and communicates with the high pressure discharge chamber 10.

A suction refrigerant pipe 23 communicating with an evaporator (not shown) is connected to a substantially central portion of the closed case 1.

An oil reservoir 24 for collecting lubricating oil is formed on the inner bottom of the closed case 1, and the lower end of the rotary shaft 3 is immersed in the lubricating oil. An oil supply pump 25 is provided at the lower end of the rotary shaft 3 and communicates with an oil supply passage 26 provided on the rotary shaft 3.

FIG. 1 shows a refrigeration cycle circuit of a refrigeration cycle apparatus equipped with the scroll compressor K.

The discharge refrigerant pipe 22 connected to the compressor K.
Communicate with the condenser 30. A capillary tube 32, which is a pressure reducing device, is connected to the refrigerant outlet side of the condenser 30 via a connection valve 31. Furthermore, an evaporator 33 is connected, which is connected via a further connecting valve 34 to the compressor K.
Communicates with the suction refrigerant pipe 23 connected to.

During the transportation from the factory shipment to the installation site, the outdoor unit containing the compressor K and the condenser 30 and the indoor unit containing the evaporator 33 are put together separately. The refrigerant is sealed in either one of the units, and the connection valves 31 and 34 are closed.

After these units are installed, the refrigerant pipes are connected to each other to open the connection valves 31 and 34. In the refrigeration cycle, there is no refrigerant cutoff point, and the refrigerant can freely flow in the cycle.

The refrigerant outlet side of the condenser 30 and the connection valve 31
The other end of the injection pipe 21 is connected to a middle portion of the refrigerant pipe Pa that communicates with the.

An electromagnetic opening / closing valve 35 is provided in the middle of the injection pipe 21.
It has a pressure sensor 36 for detecting the internal pressure of the suction pipe 23 connected to the compressor K.

When the pressure detected by the pressure sensor 36 is lower than the set pressure and the detection signal is received, the electromagnetic on-off valve 35 further states that the pressure inside the suction refrigerant pipe 23 becomes negative. It has a control function that opens when the pressure rises and closes when the pressure in the pipe is higher.

These injection pipes 21, an electromagnetic opening / closing valve 35 equipped with a pressure sensor 36 as a detector, and
The liquid injection circuit 37 is composed of a plurality of injection holes 18 provided in the fixed scroll blade 8 of the compressor K.

When the refrigeration cycle operation is started, however, in the scroll compressor K, the compression mechanism section 4 is driven to introduce the low-pressure refrigerant gas, which is the gas to be compressed, from the suction refrigerant pipe 19 to close the case. Fill within 1.

This refrigerant gas is used for the scroll compression mechanism 4
Is sucked into the compression chamber S formed between the fixed scroll vane 8 and the orbiting scroll vane 9 which constitute the above-mentioned structure through a suction port (not shown).

The refrigerant gas sucked into the compression chamber S is compressed along with the orbiting movement of the orbiting scroll blade 9, and when it reaches a predetermined pressure, it is discharged from the discharge port 16 to the high pressure discharge chamber 10 and further discharged refrigerant pipe. It is led to the external condenser 30 via 22.

As shown by the arrow in FIG. 1 (A), the refrigerant is introduced into the capillary tube 32 through the connection valve 31, where it is decompressed and then introduced into the evaporator 33. In the evaporator 33, the refrigerant evaporates to remove the latent heat of evaporation from the surroundings and perform a refrigerating action.

The evaporated refrigerant is sucked into the compressor K through the connection valve 34 and has the above-mentioned cycle structure.

The pressure sensor 36 detects the pressure in the pipe on the suction side and sends the detection signal to the electromagnetic on-off valve 35.

In a normal operating state, the pressure sensor 36 detects a suction pressure higher than the pressure value set in the electromagnetic on-off valve 35, and the electromagnetic on-off valve 35 receiving the detection signal maintains the closed state. . Therefore, the liquid injection circuit 37 does not have any action.

FIG. 6B shows that the pressure on the suction side becomes negative due to the negative pressure of the compressor K when the refrigeration cycle operation is performed with the connection valve 31 or 34 closed or when the pump is down. Is a state in which the pressure sensor 36 has detected that the pressure has become equal to or lower than the set value.

At this time, the electromagnetic on-off valve 35 receiving the detection signal of the pressure sensor 36 is opened, and a part of the liquid refrigerant discharged from the condenser 30 is guided to the liquid injection circuit 37.
The liquid refrigerant is again injected from the injection pipe 21 shown in FIG. 2 into the compression chamber S from the injection holes 18 through the recess 17 provided in the fixed scroll blade end plate portion 12 in the compressor K.

Although the compression chamber S has already reached a high temperature, it is cooled by the liquid refrigerant injected through the liquid injection circuit 37.

In particular, the blade portions 13 and 14 of the scroll blades 8 and 9 constituting the compression chamber S have a relatively small wall thickness and easily undergo thermal expansion, but if they are cooled by the liquid refrigerant and are in a high temperature overheated state. Therefore, there is no thermal adverse effect.

The temperature of the compression chamber S is lowered to the surroundings,
This leads to a reduction in the temperature of the compression mechanism section 4 and the cooling effect of the entire compressor K can be obtained, thus providing this reliable protection.

When the cause of the pressure drop below the set value on the suction side of the compressor K is eliminated and the pressure sensor 36 detects the set value or more, the electromagnetic on-off valve 35 is closed again and the liquid is closed. The injection circuit 37 is closed. That is, it returns to the normal refrigeration cycle operation.

In the above embodiment, the scroll type compressor is applied as the hermetic type compressor, but the compressor is not limited to the compressor of this type. It can also be used in compressors that compress other types of compressed gas or air.

[0049]

As described above, according to the present invention, a pressure sensor is provided at a low pressure location, and when this pressure sensor detects a negative pressure, the refrigerant between the condenser outlet side and the pressure reducing device is reduced. Since the on / off valve of the liquid injection circuit, which branches from the pipe and directly communicates with the compression mechanism of the compressor, is opened, if the inside of the compressor becomes negative pressure for some reason, immediately cool it. The effect of preventing the overheated state, providing reliable protection for the compressor, and improving reliability can be achieved.

[Brief description of drawings]

FIG. 1A is an embodiment of the present invention, showing a refrigeration cycle circuit of a refrigeration system, particularly showing a normal operation state.
(B) is a refrigeration cycle circuit of the refrigeration system, and particularly shows a negative pressure state.

FIG. 2 is a vertical cross-sectional view of a scroll compressor that is a hermetic compressor used in a refrigeration system.

[Explanation of symbols]

K ... Compressor, 30 ... Condenser, 32 ... Decompression device (capillary tube), 33 ... Evaporator, 36 ... Pressure sensor, 4
... (compressor) compression mechanism part, 37 ... liquid injection circuit, 35 ... (electromagnetic) on-off valve.

Claims (1)

[Claims] 1. A refrigeration cycle apparatus comprising a refrigeration cycle in which a compressor, a condenser, a decompression device, and an evaporator are communicated with each other via a refrigerant pipe, and a pressure sensor is provided at a low pressure portion in the refrigeration cycle. A refrigerant injection pipe is provided between the condenser outlet side of the refrigeration cycle and the pressure reducing device, and a liquid injection circuit that directly communicates with the compression mechanism portion of the compressor is connected to the liquid injection circuit. A refrigeration cycle apparatus comprising an opening / closing valve that opens when a negative pressure is detected by the.