JPS58152187A - Air conditioning apparatus - Google Patents

Abstract

PURPOSE:To prevent the discharging of lubricating oil due to its foaming, by operating a compressor at a low or intermediate speed for a certain while after starting of the compressor, and then operating the same at a high speed. CONSTITUTION:Coolant is passed in the direction shown by arrows in the drawing. However, since both of the cycle and a compressor are cool at the time just after starting of the compressor, the coolant is drawn into the compressor 1 from a suction port S in the phase of liquid, and after being compressed by the compressor 1, is then discharged from a discharge port (d). Taking the time (t) passed after starting operation of the compressor 1 at the axis of abscissa and the speed of rotation of the compressor 1 at the axis of ordinate, the speed of rotation of a compressor motor is controlled as shown by a curve 10 in the drawing, whereby the compressor performs gas compressing operation at an intermediate speed, so that the possibility of lubricating oil to cause foaming is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a capacity-controlled air conditioner, and particularly to a method of controlling a compressor during startup.

Compressors using variable speed electric motors typically start up gradually. Initially, both the compressor and the cycle are cold, so liquid refrigerant flows into the suction port of the compressor and is discharged from the discharge port by the compressor. At this time, the refrigerant dissolved in the lubricating oil accumulated in the chamber becomes bubbles and evaporates, causing a phenomenon called foaming. The degree of this forming increases as the rotation speed of the compressor increases and as the compressed refrigerant becomes more liquid.

In a compressor that is used at a high rotation speed, the rate of the above-mentioned forming increases, and eventually the lubricating oil is discharged from the discharge pipe along with the refrigerant, and the amount of oil in the compressor chamber decreases. There was a problem.

The present invention has been made to solve the above problems. That is, the purpose is to prevent lubricant oil from being discharged due to forming by controlling the compressor to operate at a low or medium rotational speed for a certain period of time immediately after startup, and then at a high rotational speed.

The present invention has determined that the discharge of lubricating oil is due to forming in the compressor chamber, and the gasification rate of the compressed refrigerant that influences the degree of forming.

This was done by focusing on the rotation speed of the compressor, especially the former. Immediately after startup, in order to increase the gasification rate of compressed refrigerant,
The objective is to control the compressor to operate at a low or medium speed until the compressor performs a gas compression operation.

Hereinafter, the present invention will be explained according to the embodiments shown in FIGS. 1 to 3. Figure 1 is a diagram of a refrigeration cycle, where 1 is a variable speed motor driven compressor, and 2 is a condenser.

3 is an expansion valve, 4 is an evaporator, S is a suction side of the compressor 1,
d is the discharge side part. The refrigerant flows in the direction of the arrow in the figure, but immediately after operation, both the cycle and the compressor are cooled, so the refrigerant is liquefied.The refrigerant is sucked in from the suction part S as a liquid refrigerant, and is compressed by the compression unit 1111. It will be discharged to the discharge section d. (So-called liquid compression state) Furthermore, the second
This will be explained in detail with reference to a sectional view of the compressor 1 shown in the figure. 5 is
The variable speed electric motor has a stator section, 6 a rotor section, 7 a compressor machine section, 8 a lubricating oil interface when stationary, and 9 a tightly closed chamber. The liquid refrigerant flowing in from the suction part S is compressed by the compression machine part 7 and discharged into the chamber 9.
There is liquid lubricating oil in the discharge area. However, in a saturated state, this lubricating oil contains a portion of the refrigerant that occupies the interior of the chamber.

The refrigerant evaporates. This is a so-called forming phenomenon. This forming phenomenon spreads throughout the chamber 9 and reaches the vicinity of the discharge portion d.

Eventually, not only the refrigerant but also the lubricating oil will be discharged.

However, in the present invention, since the rotation speed control method shown in FIG. 3 is adopted, the amount of the lubricating oil discharged can be reduced. That is, in FIG. 3, when the time t from the start of operation is plotted on the horizontal axis and the rotational speed of the compressor is plotted on the vertical axis, the rotational speed of the compressor motor is controlled as shown by curve 10. Conventionally, if the compressor is controlled as shown by curve 11, the compressor will rotate at high speed while remaining in a cold state, leading to the discharge of lubricating oil, but as in the case of the present invention.

If the control is performed as shown in curve 10, the compressor will completely switch to gas compression operation at an intermediate rotation speed, and forming will be less likely to occur. According to the implementation results, the duration time at intermediate rotation speed is 2~
Foaming could be sufficiently suppressed within 3 minutes. Since this duration varies depending on the type of compressor, etc., it goes without saying that it can be changed as appropriate.

According to the present invention, it is possible to prevent lubricating oil from being discharged when starting a cold compressor by simply changing the rotation speed control method after starting the compressor, which uses a variable speed electric motor as the drive source. Locks can be avoided.

[Brief explanation of the drawing]

FIG. 1 is a diagram of a refrigeration cycle, FIG. 2 is a sectional view of a variable speed motor-driven compressor, and FIG. 3 is a diagram of a rotation speed control mode after startup of the present invention. 1... Compressor, 2... Condenser, 3... Expansion valve, 4
...Evaporator, S...Suction part, d...Discharge part, 5.
... Stator of variable speed electric motor, 6... Rotor part, 7.
... Compression machine part, 8... Lubricating oil interface, 9... Close-tight chamber, 10... Rotation speed control mode of the present invention, 11
...Conventional rotation speed control style, t...Time after startup,
N... Compressor rotation speed. Figure l Figure 2 Figure 3 Procedural amendment (method) Indication of the case 1982 Patent Application No. 33873 Title of the invention Person who makes amendments to air conditioner 451 1 (4 types 2 gods [1 standing Work place 1
', 2i M l,: 1) Win
Scope of Claims in the Specification and the Denomination of the Specification.

Claims (1)

[Claims] 1. In an air conditioner consisting of a compressor driven by a variable speed electric motor and a heat exchanger that absorbs and radiates heat by expanding and condensing refrigerant, the number of revolutions is gradually increased after the start of operation, and the number of revolutions is increased until a certain number of revolutions is reached. An air conditioner that operates for a certain period of time and then controls the compressor to further increase the rotation speed.