JPH10148405A - Refrigerating/air-conditioning equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the lowering of the concentration of a lubricant as caused by the mixing of a refrigerant into the lubricant of a compressor used in a refrigeration cycle of refrigerating/air-conditioning equipment. SOLUTION: In refrigerating/air-conditioning equipment having a refrigerating cycle in which a compressor, a non-application side heat exchanger, a pressure reducing device and an application side heat exchanger are connected sequentially, a heater 12 is provided in the compressor to heat it, a temperature sensor 11 to detect the temperature of the compressor and a delivered gas condensing temperature sensor 28 to detect the condensing temperature of a delivered gas from the compressor. The heater 12 is controlled by a control means 30 based on temperatures detected of the temperature sensor and the delivered gas condensing temperature sensor. Thus, the temperature of a lubricant after the starting in the compressor is kept higher than that of the delivered gas condensing temperature thereby preventing the mixing of a refrigerant into the lubricant in the compressor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration / air conditioner having a refrigeration cycle in which a compressor, a non-use side heat exchanger, a pressure reducing device, and a use side heat exchanger are sequentially connected. The present invention relates to a refrigeration / air conditioner that maintains the temperature of oil higher than the condensation temperature of a discharge gas.

[0002]

2. Description of the Related Art An example of the prior art is disclosed in Japanese Unexamined Patent Publication No. 5-539.
As described in Japanese Patent Publication No. 53-53, in a hermetic compressor, in a structure having a low suction pressure in a closed container, a thrust force generated in a scroll is processed and oil is supplied to a bearing portion of an orbiting scroll. However, in such a conventional example, no consideration is given to lubricity due to the temperature, viscosity, and the like of the lubricating oil in the compressor after the compressor is started.

[0003]

When the temperature of the lubricating oil supplied to the internal mechanism that requires lubrication of the compressor is lower than the condensation temperature of the discharge gas after the start of the compressor,
Refrigerant of the discharge gas dissolves in the lubricating oil, lowering the viscosity of the lubricating oil, and consequently lowering the lubricity of the internal mechanism of the compressor,
Doing so may cause overheating and wear of the internal mechanism.

[0004] The present invention solves the above problems,
The temperature of the lubricating oil in the internal mechanism of the compressor and the oil sump is prevented from lowering than Tc (meaning the discharge gas condensing temperature, hereinafter abbreviated as Tc) after the start of the compressor, An object of the present invention is to provide a refrigeration / air conditioner that ensures lubricity and improves reliability.

[0005]

In order to achieve the above object, a first invention of the present application is directed to a refrigeration system in which a compressor, a non-use side heat exchanger, a pressure reducing device, and a use side heat exchanger are sequentially connected. In a refrigeration / air conditioner having a cycle, a heater provided in the compressor for heating the compressor, a temperature sensor for detecting the temperature of the compressor, and detecting a condensation temperature of gas discharged from the compressor. The heater is controlled based on the discharge gas condensing temperature sensor and the detected temperature of the temperature sensor and the discharge gas condensing temperature sensor so as to maintain the temperature of the lubricating oil in the compressor after startup at a temperature higher than the discharge gas condensing temperature. And control means.

A second invention of the present application is directed to a refrigeration / air conditioner having a refrigeration cycle in which a compressor, a non-use side heat exchanger, a pressure reducing device, and a use side heat exchanger are sequentially connected. A heater provided for heating the compressor, a temperature sensor for detecting a temperature of the compressor, a discharge gas condensing temperature sensor for detecting a condensing temperature of a gas discharged from the compressor, the temperature sensor and a discharge gas condensing Control means for controlling the capacity of the compressor based on the temperature detected by the temperature sensor so as to maintain the temperature of the lubricating oil in the compressor after startup at a temperature higher than the discharge gas condensing temperature.

According to a third aspect of the present invention, in the refrigeration / air conditioner according to the first aspect, the temperature of the lubricating oil after startup in the compressor is determined based on the temperature detected by the temperature sensor and the discharge gas condensation temperature sensor. It has a control means for controlling the capacity of the compressor so as to maintain the temperature higher than the discharge gas condensing temperature.

A fourth invention of the present application is characterized in that a heat insulating material for keeping the compressor warm is provided around the compressor in any one of the first to third aspects.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 3 using an example of an air conditioner using a scroll compressor.

In the figure, a compressor 1 has a casing 2 in which a scroll compression mechanism 5,
A motor 9 and a crankshaft 8 rotatably supported by roller bearings 6 and a lower bearing 7 for transmitting the driving force of the motor to the compression mechanism unit 5 are built in. Are formed. A suction pipe 3 and a discharge pipe 4 are fixed to the casing 2, a temperature sensor 11 of the compressor is provided at an upper part of the casing 2, and a heater 12 is wound around an upper part and a lower part of the outer periphery of the casing.

Next, an example of an air conditioner equipped with the above-described compressor 1 will be described. After the start of the compressor 1, the refrigerant enters the compression chamber of the compression mechanism 5 through the suction pipe 3 and is compressed, and contacts the lubricating oil reservoir 10 through the inner wall of the casing 2 and the gap on the outer periphery of the stator of the motor 9. After the heat exchange, the fluid is discharged from the discharge pipe 4 through the rotor and the stator of the motor.

The refrigerant discharged from the discharge pipe 4 is supplied to the four-way valve 2
0, passes through the outdoor non-use side heat exchanger 21, is cooled by air by a fan 27 driven by a motor 26, and is sent to an expansion valve 22, which is a decompression device, and an indoor use side heat exchanger 23, where the motor The heat is exchanged with the indoor air blown by the indoor fan 25 driven by 24. Then the refrigerant
It returns to the suction pipe 3 of the compressor through the four-way valve 20.

Next, FIG. 2 shows changes in Tc (discharge gas condensing temperature) and the oil temperature (oil temperature 1, oil temperature 2) of the lubricating oil reservoir 10 with elapsed time. In particular, in the normal case where the temperature control of the oil temperature is not performed, at the time t0 immediately before the start of the compressor 1, the oil sump 1
Although the oil temperature of 0 is higher than Tc, the oil temperature tends to decrease until a certain time t1 (for example, about 20 minutes), then increase and stabilize at time t3. On the other hand, Tc (discharge gas condensing temperature) rapidly rises immediately after startup, and thereafter, the temperature rise tends to be gradual and tends to stabilize at time t2.

That is, from the time immediately after the start up until the temperature Tc becomes stable, the temperature of the discharge gas in the compressor 1 is controlled by the inner wall of the casing 2,
Since the temperature is lower than the temperature of the motor 9, the crankshaft 8, the oil sump 10, etc., the discharge gas takes heat from the compression chamber 5 until it leaves the discharge pipe 4, and the oil temperature tends to decrease as described above. Is shown. If the heat retention in the oil reservoir 10 immediately before the start is insufficient, the oil temperature becomes lower than Tc (condensation temperature of the discharge gas) as in the case of the oil temperature 1, and the refrigerant as the discharge gas condenses. The refrigerant mixes with the lubricating oil, and lowers the viscosity of the oil. This lowers the lubrication of the compression chamber 5, the roller bearing 6, the lower bearing 7, the crankshaft 8 and the like in the compressor 1, and causes overheating of the sliding portion and the like. It causes wear.

In the present invention, oil temperature control is performed in order to prevent the above-mentioned decrease in lubrication. In the present embodiment, the control unit 3
The heating temperature of the lubricating oil is controlled by the heater 12 according to 0, and the lubricating oil temperature is changed as shown in FIG. 2 to maintain the oil temperature at a temperature higher than Tc. An example of the control for that is performed as follows. The temperature sensor 11 is provided in the compressor, and a pressure sensor 28 is provided in the discharge pipe 4. The condensing temperature is converted from the discharge pressure detected by the pressure sensor 28. The oil temperature and the discharge gas pressure are detected by the sensors 11 and 28 at fixed time intervals from t0 immediately after the startup, and the detection signals are input to the comparison circuit 31 of the control unit 30. In that case, a signal corresponding to the discharge gas condensing temperature converted from the discharge pressure is input to the comparison circuit. The comparison circuit 31 compares the oil temperature with Tc. If the difference is smaller than a predetermined value at each time, the control unit 3
From 0, a signal for turning on the heater 12 is issued, and heating by the heater is performed. Conversely, if the difference is larger than the predetermined value, a heater OFF signal is output and the heater is not heated. Such control is performed until the minimum expected time t1 of the oil temperature, but the control thereafter may be continued. As described above, according to the present embodiment, the oil temperature and the discharge gas condensing temperature are detected, and the oil temperature is controlled to be heated based on the detection result. Mixing into lubricating oil can be prevented.

(Embodiment 2) Next, a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, a heat insulating material 13 is wound around the compressor 1, and the sensor 11 is provided at fixed short time intervals as in the above-described embodiment.
And 28, the oil temperature and the discharge pressure condensation temperature Tc1 are detected, and the two temperatures are compared by the comparison circuit 31. In the present embodiment, when the compared temperature difference is smaller than the predetermined value, the controller 30 changes the rotation speed of the compressor via, for example, an inverter circuit to reduce the capacity of the compressor, that is, the discharge amount. As a result, FIG.
, The oil temperature is maintained at a temperature equal to or higher than the discharge gas condensing temperature, and it is possible to prevent the refrigerant from being mixed into the oil.

(Embodiment 3) In this embodiment, as shown in FIG. 5, the compressor 1 is heated by the heater 12 and is kept warm by the heat insulating material 13. By combining the capacity control of the compressor, the refrigerant is prevented from being mixed into the oil. In the case of the present embodiment, the heat insulating material may be omitted.

In each of the above embodiments, the heater 12 is provided at the upper and lower portions of the outer periphery of the casing, and the temperature sensor 11
Is provided at the upper part of the casing, these heaters and temperature sensors may be provided inside or near the oil reservoir 10, and the discharge gas condensing temperature is detected instead of the discharge pressure sensor. May be provided in the use side heat exchanger to directly detect. Further, the present invention can be implemented not only as an air conditioner but also as a refrigerator, and a rotary compressor other than a scroll compressor can be used as a compressor.

[0019]

As described above, according to the present invention,
By controlling the heating of the oil temperature in the compressor or controlling the capacity of the compressor, the oil temperature is always maintained at a temperature equal to or higher than the discharge gas temperature, the refrigerant is prevented from being mixed into the oil, and due to poor lubrication inside the compressor. , Abnormal overheating, abnormal wear and the like can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of a compressor unit according to an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the passage of time during the operation of the compressor and the condensing temperature of the discharged gas and the lubricating oil temperature.

FIG. 3 is a schematic view of an air conditioner according to an embodiment of the present invention.

FIG. 4 is a diagram showing the relationship between the passage of time and the discharge gas condensing temperature and the lubricating oil temperature during the operation of the compressor according to the second embodiment of the present invention.

FIG. 5 is a diagram showing a structure of a compressor unit according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a structure of a compressor unit according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor 2 ... Casing 3 ... Suction pipe 4 ... Discharge pipe 5 ... Compression chamber 6 ... Roller bearing 7 ... Lower bearing 8 ... Crankshaft 9 ... Motor 10 ... Oil sump 11 ... Compressor temperature sensor 12 ... Heater 13 ... Heat retention Material 28: Discharge pressure sensor 30: Control unit 31: Comparison circuit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shunji Sasaki 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture Inside Air Conditioning Systems Division, Hitachi, Ltd. (72) Inventor Kunio Sato 390 Muramatsu, Shimizu-shi, Shizuoka Air Conditioning System Business, Hitachi, Ltd. Inside

Claims (4)

[Claims] 1. A refrigeration / air conditioner having a refrigeration cycle in which a compressor, a non-use-side heat exchanger, a pressure reducing device, and a use-side heat exchanger are sequentially connected, wherein the compressor is provided to heat the compressor. Heater, a temperature sensor that detects the temperature of the compressor, a discharge gas condensation temperature sensor that detects the condensation temperature of the discharge gas from the compressor, and a temperature sensor and a discharge gas condensation temperature sensor that detect the condensation temperature. Control means for controlling the heater so as to maintain the temperature of the lubricating oil in the compressor after startup at a temperature higher than the discharge gas condensing temperature. 2. A refrigeration / air conditioner having a refrigeration cycle in which a compressor, a non-use side heat exchanger, a pressure reducing device, and a use side heat exchanger are sequentially connected, wherein the compressor is provided in the compressor and heats the compressor. Heater, a temperature sensor that detects the temperature of the compressor, a discharge gas condensation temperature sensor that detects the condensation temperature of the discharge gas from the compressor, and a temperature sensor and a discharge gas condensation temperature sensor that detect the condensation temperature. Control means for controlling the capacity of the compressor so as to maintain the temperature of the lubricating oil in the compressor after startup at a temperature higher than the discharge gas condensing temperature. 3. The refrigeration / air conditioner according to claim 1, wherein the temperature of the lubricating oil after startup in the compressor is higher than the discharge gas condensing temperature based on the detection temperatures of the temperature sensor and the discharge gas condensing temperature sensor. A refrigeration / air conditioner comprising control means for controlling the capacity of the compressor so as to maintain the temperature of the compressor. 4. The refrigeration / air conditioner according to claim 1, wherein a heat insulating material for keeping the compressor warm is provided around the compressor.