JPS6138369A - Refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to refrigerant control in a refrigeration device of a refrigerator or an air conditioner, and more particularly, to refrigerant control suitable for improving the stability and coordination of a refrigeration cycle.

[Background of the invention]

FIG. 5 shows a refrigeration cycle using a conventional electric expansion valve. In FIG. 5, 1 is a compressor, 2 is a condenser, 3 is an evaporator, 4 is an electric expansion valve, 5 is a control circuit for the electric expansion valve, 6 is a compressor suction refrigerant filling sensor, and 7 is an electric expansion valve. It is an evaporation temperature sensor. Further, FIG. 6 shows the relationship between the valve lift and the opening area of the electric expansion valve, and the opening area characteristic (2) is the characteristic of the conventional electric expansion valve. In conventional electric expansion valves, the maximum valve opening area was determined by the maximum refrigerant flow rate in the steady state of the refrigeration cycle. A conventional refrigeration cycle will be explained with reference to FIG. In the steady state of the refrigeration cycle, the electric expansion valve is operated by the control circuit 5 so that the refrigerant superheat degree calculated based on the temperatures detected by the suction refrigerant temperature sensor 6 and the evaporation temperature sensor 7 becomes the set refrigerant superheat degree. Controls the valve opening degree of 4.

Furthermore, in a transient state after the compressor is started, the valve lift is controlled to be maximum, that is, the valve opening area is maximized. The reason why the valve opening area is maximized in this transient state is to prevent the suction pressure from decreasing abnormally after startup.

FIG. 7 shows the pattern of the valve opening area and the temporal change in suction pressure after startup, and the broken line shows the characteristic when the valve opening area characteristic (2) is used.

Conventionally, the capacity of the electric expansion valve, that is, the maximum valve opening area, was selected based on a steady state, so even if the valve opening area was maximized after startup, it was not effective in preventing a drop in suction pressure. However, a stable cycle can be obtained in steady state.

In order to prevent this drop in suction pressure after startup, an electrically operated expansion valve having a large valve opening area at maximum lift, as shown in characteristic (2) in FIG. 6, may be used. However, in the electric expansion valve having the characteristic (2) shown in FIG. 6, the rate of change in the valve opening area with respect to a change in valve lift is large, and therefore, the refrigerant it changes significantly even with a slight change in valve lift.

FIG. 7 shows an example of control of the valve opening area when using an electric expansion valve with a valve opening area % ratio of (2), and the temporal change in suction pressure after startup is shown by a dashed-dotted line. As shown in FIG. 7, when an electric expansion valve having a valve opening area characteristic (3) is used, a drop in suction pressure after startup is prevented. However, in a steady state, the change in valve opening area/change in valve lift is large, so the refrigeration cycle tends to become unstable.

In other words, the coordination in the transient state of the refrigeration cycle is improved (the capacity t' of the electric expansion valve may be increased, but
In a steady state, there was a problem in that the pressure and vorticity of the refrigeration cycle were hunting.

[Purpose of the invention]

The present invention was invented in view of the above-mentioned problems, and it is possible to control the refrigerant to make the refrigeration cycle stable in a steady state, and to improve the continuity of the refrigeration cycle during transient states of the refrigeration cycle such as startup and defrosting. The purpose is to provide an improved refrigerant control method.

[Summary of the Invention] In order to achieve the above object, the present invention provides a compressor, a condenser,
An electric expansion valve and an evaporator are sequentially connected via piping to form a refrigerant circuit, and the above expansion valve has a small valve opening area change/lift change up to a set lift, and above the above set lift, the valve opening changes. The area change/lift change is large, and in the normal state of the refrigerant circuit, the opening area of the expansion valve is controlled within a range where the above valve opening area change is small, and during operation and defrosting, the above valve opening area change is The invention is characterized in that it includes an expansion valve that controls the opening area of the expansion valve over a large range.

An embodiment of the present invention will be described below. FIG. 1 shows the relationship between the valve lift and the valve opening area of the electric expansion valve according to the present invention.

As shown in FIG. 1, the electric expansion valve according to the present invention has a small change in valve opening area with respect to a change in valve lift when the valve lift is up to Q-LM, and when the valve lift is from LM to 1.0, the change in valve opening area is small. FIG. 2 shows an example of the needle shape of the Rokuma Meme Oboro valve, which has the characteristic of having a large change in the valve opening area with respect to the valve opening area. In FIG. 2, 11 is a needle and 12 is an orifice. The needle 11 is formed in such a shape that its diameter rapidly decreases at the tip. Further, the needle 11 is moved up and down by a drive device such as a pulse motor or an electromagnet (not shown). In FIG. 2, the needle position indicated by a solid line indicates the fully closed state, and the broken line indicates the valve lift state shown in FIG. Until the state shown by the broken line in FIG. 2, the needle 11
As the needle 11 moves upward, the valve opening area gradually increases as shown in FIG. 1, and above the broken line position, as the needle 11 rises, the valve opening area increases rapidly.

Although the shape shown in FIG. 2 has been described as an example, the shape of the needle other than the shape shown in FIG. 2 is also possible to obtain the characteristics shown in FIG.

The expansion valve control method of the present invention will be explained below.

By using an expansion valve having the characteristics shown in Fig. 1, it is possible to prevent a drop in suction pressure by controlling the valve lift in the range of LM to 1.0 at startup. Furthermore, in a steady state, the change in valve opening area/valve lift is small, making it possible to stabilize the refrigeration cycle.

Figure 3 shows the control pattern of the valve opening area and the temporal change in suction pressure when an electric expansion valve having the valve opening area percentage shown in Figure 1 is used. During this period, the valve lift is kept constant within the range of LM to 1.0 in FIG. 1, and after a certain period of time, control is shifted to steady state control, for example, superheat degree control as described in the conventional example. Therefore, it is possible to prevent the suction pressure from decreasing after startup, greatly improving the compatibility of the refrigeration cycle, and when controlling the degree of superheating in a steady state, a stable refrigeration cycle can be obtained.Next, in Fig. 1, It has been proven that setting the ratio of the maximum valve opening area AMAx to the valve opening area Aθ required in the steady state by 2 to 4 times is effective in improving the coordination in the transient state.

Next, FIG. 4 shows another embodiment regarding the control pattern of the valve opening area. Figure 4 shows a system in which the valve opening area is changed according to a temporally predetermined pattern in the range of 1.0 from the valve lift (valve lift) LM from the state where the valve is fully open after startup, and the control is shifted to a steady state. In this case, there is little change in the valve opening area, and the refrigeration cycle can be quickly brought to a steady state.

The control method at startup has been explained above, but even in defrosting operation during the heating period, by controlling the valve opening in the range of LM-1,0 (valve lift), it is possible to prevent a drop in suction pressure immediately after the start of defrosting. , this expansion valve control method is particularly effective in shortening defrosting time.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to improve the coordination of the refrigeration cycle at the time of startup and defrosting, it is possible to save power, and by being applicable to heat pumps capable of cooling and heating, Comfort when starting air conditioning or heating is greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between valve lift and valve opening area of an electric expansion valve according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the shape of the needle of the expansion valve, and FIGS. FIG. 4 shows starting characteristic diagrams of refrigeration cycles using electric expansion valves according to embodiments of the present invention. Figure 5 is a configuration diagram of a general refrigeration cycle using a conventional electric expansion valve, Figure 6 is a diagram showing the relationship between valve lift and valve opening area of a conventional electric expansion valve, and Figure 7. 1 is a diagram showing the characteristics after the start of a cycle using a conventional electric expansion valve. l...Compressor 2. ...Condenser 8...Evaporator
4...Electric expansion valve 11...Needle 12...
・Orifice Patent Attorney Akio Takahashi

Claims (1)

[Claims] 1. A compressor, a condenser, an electric expansion valve, and an evaporator are sequentially connected via piping to form a refrigeration cycle, and the expansion valve has a valve opening area change/lift up to a set lift. The change is small, and above the above set lift, the valve opening area change/lift change is large, and in the steady state of the refrigeration cycle, the opening area of the expansion valve is controlled within the range where the above valve opening area change is small, and the start A refrigeration system characterized in that the opening area of the expansion valve is controlled within a range in which the change in the valve opening area is large during cooling and defrosting. 2. The refrigeration system according to claim 1, wherein the valve lift is controlled according to a control pattern set in advance for time during startup and defrosting. 3. The maximum valve opening area of the electric expansion valve is set to 2 to 2 of the valve opening area at the time of valve lift, where the relationship between valve lift and valve opening area changes.
The refrigeration device according to claim 1, which is quadrupled.