JPS6024315B2 - Refrigerant compressor operation control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an operation control method for automatically controlling the operation and shutdown of a refrigerant compressor.

FIG. 1 shows a part of a commonly used control circuit for a cold soot compressor.

In the figure which is a circuit connection diagram, 1 and 2 are power lines, 3
is an electromagnetic switch for the compressor, and when the electromagnetic switch 3 is excited, the compressor motor (not shown) starts, and the electromagnetic switch 3
When the compressor motor is demagnetized, the compressor motor stops. 4 is a temperature switch that excites and demagnetizes the electromagnetic switch 3 for the compressor, and a temperature detection end (not shown) detects the temperature of the cooling load of the air in the refrigerator, for example, and depending on the temperature of the cooling load with respect to the set temperature, The movable saddle piece 4a and the fixed contact 4b are connected, or the movable saddle piece 4a and the fixed contact 4c are connected, and the movable saddle piece 4a and the fixed contact 4b are opened.

Figure 2 shows the movable piece 4a of the temperature switch 4, the fixed contact 4b,
A diagram showing the operating procedure of 4c shows the temperature on the shaft and the connection of the internal contacts on the shaft. TN is the temperature at which the compressor starts, TF is the temperature at which the compressor stops, and there is a relationship of TF<TN. Next, the operation will be explained.

When the compressor is operated, the temperature of the cooling load decreases and the temperature reaches TF.
When this happens, the compressor will stop. If it remains stopped, the temperature of the cooling load will rise over time. When the temperature rises to TN, the compressor starts operating again. In FIG. 2, ON on the vertical axis indicates that the movable bush piece 4a and the fixed contact point 4b of the temperature switch 4 are connected, and OFF indicates that the movable bush piece 4a and the fixed contact point 4b are opened. FIGS. 3 and 4 show characteristic curves showing temperature changes in the cooling load and compressor shutdown when the compressor is automatically shut down using such a method. FIG. 3 shows a characteristic curve when the cooling capacity (capacity obtained by operating the compressor) is sufficiently large relative to the cooling load.

The machine axis is time and the vertical axis is the temperature of the cooling load. As the compressor operates, the temperature of the cooling load decreases, and when the temperature reaches TF, the compressor stops, and the temperature increases as time passes. When this temperature reaches the set temperature TN, the compressor starts again and the cooling cycle is repeated. FIG. 4 is a characteristic curve showing the temperature change of the cooling load when the cooling capacity and the cooling load become almost equal as the temperature of the cooling load approaches TF.

The cooling capacity changes depending on the temperature of the cooling load, and it is generally well known that the lower the temperature, the lower the capacity, and conversely the cooling load increases. Figure 4 shows the cooling load per unit time. The temperature drop gradually decreases, and there is almost no temperature drop near the temperature TF, indicating that the compressor will eventually operate constantly. By the way, the purpose of a refrigeration device, which is a cooling equipment for a refrigerator, is to maintain the temperature of stored items at a certain level or lower, and this temperature is almost the same as the set temperature TN shown in the explanation so far. Note that it is common to manage the product temperature using the temperature of a heat medium such as air as a guide, rather than directly detecting the product salt.

On the other hand, when the temperature of the cooling load is the set temperature TN, a refrigerator is usually installed with a capacity that has a cooling capacity greater than the cooling load, so the temperature of the cooling load is necessarily the set temperature TN.
It goes down below. Therefore, the operation of the refrigerator must be controlled by determining how many times the temperature must drop below the set temperature TN to stop the refrigerator. This temperature is the lower limit temperature TF shown in the explanation so far.
It is. However, if this method of determining the lower limit temperature TF is continued, as shown in FIG. 4, operating costs will become higher than necessary due to the constant operation of the compressor.

Figure 5 shows the case where the temperature TF is set close to TN to avoid wasteful operation as shown in Figure 4, and shows that when the cooling load is small, frequent shutdowns of the compressor occur. There is. If the compressor stops operating frequently, a large amount of oil will rise, which not only accelerates the wear of the moving parts, but also raises the risk of overheating and burning out the compressor motor. Furthermore, it is difficult to change the lower limit temperature TF for stopping the compressor each time the cooling load changes on a daily basis. Therefore, the results tend to be as shown in FIGS. 4 and 5. This invention takes into account the above points and adjusts the set temperature T.
Intermediate temperature TFx in the relationship N>TFx>lower limit temperature TF
A second temperature switch that opens and closes when specified and detected, and a time limit switch that operates from time zero after the compressor starts are used, so that even if the temperature of the cooling load has not fallen to the lower limit temperature TF, is below the specified intermediate temperature TFx, and after the compressor is started, if the time set by the time-limited relay 6 described above has elapsed, the compressor is stopped to stop wasteful operation of the compressor and when the cooling load is small. However, the present invention provides a control method that prevents frequent repetition of operation and stop.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Fig. S shows a part of a control circuit of a compressor showing an embodiment of the present invention. In this figure, 5 is a second temperature switch, and when the temperature of the cooling load decreases to the intermediate specified temperature TFx, 5 is a second temperature switch. For example, the movable contact piece 5a is connected to the fixed contact 5c, and when the temperature rises to the set temperature TN, the movable straw piece 5a opens from the fixed contact 5c. Reference numeral 6 denotes a time-limiting relay that operates from time zero when the compressor electromagnetic switch 3 is energized, and returns to zero when the relay 6 is demagnetized.

Reference numeral 7 denotes an auxiliary relay, in which the movable square piece 5a of the second temperature switch 5 is connected to the fixed contact 5c, and the time-limited contact T of the time-limited relay 6 is connected.
When a is closed, it is energized, the rear point xb is opened, and the compressor electromagnetic switch 3 in series therewith is demagnetized.

Others are the same as before. That is, as shown in this control circuit, unlike the conventional one, the movable bush piece 4a of the temperature switch 4
Even if the fixed contact 4b does not open, if the movable bushing piece 5a of the second temperature switch 5 connects with the fixed contact 5c and the set time of the time-limited relay 6 has elapsed, the contact Ta closes and the auxiliary relay 7 is excited, and the contact Xa in parallel with the contact Ta closes.
When the contact Xb opens, the compressor electromagnetic switch 3 is demagnetized and the compressor motor (not shown) is stopped.

At the same time, the time-limited electric appliance 6 is set by the contact Ca working on the electromagnetic switch 3. FIG. 7 is a diagram that collectively shows the operating procedures of the first temperature switch 4 and the second temperature switch 5 shown in FIG. 2, and in this example, the return temperatures of the two switches are set. The set temperature TN is shown as being the same.

The rest is similar to Figure 2. A description will be given using a characteristic curve showing the temperature change of the cooling load and the stoppage of the compressor when the compressor is automatically controlled by the compressor operation control method according to the present invention. FIG. 8 shows a case where the refrigerating function is sufficiently large relative to the cooling load, and the characteristics are the same as those shown in FIG. 3, where there are no particular problems with the conventional operating method. In the figure, "to" indicates the setting time of the time-limited relay 6. Figure 9 shows the characteristics that should be compared with Figure 4, which shows the conventional characteristics.The compressor does not operate until the temperature TF at which the refrigeration function gradually decreases and the cooling load increases, and the set time to of the time-limited relay 6 has elapsed. This indicates that the compressor will automatically stop. In this case, the temperature drops to the temperature TFx of the cooling load during the elapse of time to, but does not reach the temperature TF. Therefore, as in the conventional case, the temperature TF
There is no need to bring the compressor close to the TN, so there is no concern that the compressor will stop operating frequently. Figure 10 shows the characteristics when the cooling load is larger than that shown in Figure 9, and even after time elapses, the intermediate specified temperature T
The compressor continues to be operated until the temperature drops to Fx, and when the temperature reaches the intermediate specified temperature TFx, the compressor is stopped.

FIG. 11 shows the characteristics when the cooling load is very large and does not even reach the intermediate specified temperature TFx, but this is clearly different from the control example shown in FIG. 4 for the slave.

In other words, the saturation temperature in FIG. 11 is a temperature essential for maintaining the product temperature, whereas the saturation temperature in FIG. 4 can be said to be a pointless temperature that unnecessarily lengthens the compressor operating time.
In the above embodiment, the time-limited relay 6 operates after the compressor starts (
However, if a time-limited relay 7' is conveniently used in place of the auxiliary relay 7 in FIG. 6 as shown in FIG. 12, the movable contact piece 5a of the second temperature switch 5 becomes the fixed contact 5c. The compressor can be started after being connected and then stopped after a set time has elapsed.

Figure 13 shows the characteristics equivalent to Figure 9 in this case;
This will be the case. Furthermore, the temperature switches 4 and 5 can be physically integrated. As described above, according to the present invention, the temperature at which the compressor is stopped is automatically determined according to the relative difference between the cooling capacity and the cooling load, so the temperature TF at which the compressor is stopped is set each time for the load. There is no need to manage the temperature, and the required temperature is maintained and the operating time of the compressor is shortened, reducing continuous costs, preventing frequent shutdown of the compressor, and extending the life of the compressor. I can do it.

[Brief explanation of the drawing]

Fig. 1 is a circuit connection diagram showing part of the commonly used control circuit for a compressor, Fig. 2 is a diagram showing the operation procedure of the internal contacts of a general temperature switch, Fig. 3, FIGS. 4 and 5 are characteristic curve diagrams showing temperature changes in the cooling load and compressor operation stop when performed using a conventional operation control method, and FIG. 6 is a compressor control diagram showing an embodiment of the present invention. FIG. 7 is an electrical system diagram showing a part of the circuit; FIG.
9, 9, 10, and 11 are characteristic curve diagrams showing the temperature change of the cooling load and the operation stoppage of the compressor when the operation control method of the present invention is used. 12 is an electrical system diagram showing a partially modified embodiment of the present invention in FIG. 6, and FIG. 13 is a characteristic curve diagram of FIG. 12 corresponding to FIG. 9. In the figure, 3 is an electromagnetic switch for the refrigerant compressor, 4 is a first temperature switch, 5 is a second temperature switch,
6 is a time-limited relay, and 7 is an auxiliary relay. Hakama l diagram 2nd figure 3 figure 4 figure 5 figure 6 figure 7 figure 7 figure 8 figure 9 figure obi l○ figure Hakama River figure - 2 figure figure is figure

Claims (1)

[Claims] 1. Refrigerant compression that starts the compressor when the temperature of the cooling load rises to the compressor start set temperature T_N, and stops the compressor when the temperature of the cooling load falls to the compressor stop set temperature T_F. In the machine operation control method, an intermediate temperature T_F_X between the compressor start set temperature T_N and the compressor stop set temperature T_F is set, and the cooling load is increased by a predetermined time t_O after starting the compressor. If the temperature drops to the compressor stop set temperature T_F, the compressor is stopped at this point, and when the predetermined time elapses, the temperature of the cooling load becomes the intermediate set temperature T_F_X and the compressor stop set temperature. A method for controlling the operation of a refrigerant compressor, characterized in that the compressor is stopped when the predetermined time t_O has elapsed if the temperature has dropped to between T_F and t_F. 2. A refrigerant compressor operation control method in which the compressor is started when the temperature of the cooling load rises to the compressor start set temperature T_F, and the compressor is stopped when the temperature of the cooling load falls to the compressor stop set temperature T_F, An intermediate temperature between the compressor start set temperature T_N and the compressor stop set temperature T_F is set, and from the point at which the temperature of the cooling load falls to the intermediate set temperature T_F_X after the compressor starts. If the temperature of the cooling load further drops to the compressor set temperature T_F by the time the predetermined time t_O′ has elapsed, the compressor is stopped at this point, and the temperature of the cooling load is stopped for the predetermined time t_O.
If the temperature of the cooling load has fallen to a temperature between the compressor stop set temperature T_F and the intermediate set temperature T_F_X when O' has elapsed, the compressor is stopped when the predetermined time t_O' has elapsed. A refrigerant compressor operation control method characterized by: