JPS6237983Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a refrigeration system, and in particular, a refrigeration system that can stably continue operating under conditions of different outside temperatures. Regarding the configuration of

(Conventional technology) When using a cooling-only chiller equipped with an air-cooled condenser in a region with high temperatures, safety devices are required because when the outside temperature rises extremely, the condensing temperature and pressure rise rapidly. It often happens that the high-pressure switch installed in the refrigeration system activates and completely shuts down the refrigeration equipment.

(Problem that the invention aims to solve) Generally, the compressor stops when the outside temperature is 50°C to 52°C, which narrows the operable range and makes it difficult to use it in tropical regions such as the Middle East. There was a problem that caused some inconvenience.

Further, in ironworks, similar problems to those described above have occurred in refrigeration equipment that cools the cabs of cranes installed in factories with blast furnaces, etc., due to the high ambient temperature.

As a countermeasure against this problem, for example, as shown in Japanese Utility Model Publication No. 51-4321, there is a method of detecting high pressure using a high pressure switch for high pressure control and reducing the capacity of the compressor in the event of overload. However, this still has the following problems.

In other words, the set pressure of the high-pressure switch for high-pressure control is normally set lower than the set pressure of the high-pressure switch for safety equipment, so in an air-cooled cooling system, the high pressure may change depending on the outside temperature. It is effective under conditions where the pressure is higher than the set pressure of the high pressure switch for safety equipment, but the high pressure due to the outside air temperature is lower than the set pressure of the high pressure switch for safety equipment, and the high pressure for high pressure control is Despite the fact that 100% of the compressor function power can be used under conditions where the pressure is higher than the set pressure of the switch. Some of the capabilities will be reduced, and the compression function will not be effectively demonstrated.

In order to deal with this situation, the present invention provides continuous refrigeration with a partially reduced capacity when it is known in advance that the high pressure will be higher than the set pressure of the high pressure switch for the safety device. Ensure that the operation is stable, and conversely, if it is known in advance that the high pressure will not increase as much as mentioned above.
This is intended to enable 100% performance, especially when a selection switch is provided in series with a high-pressure switch for high-pressure pressure control, and the selection switch is closed during high-pressure control operation. When a certain pressure is reached, a solenoid is activated to force the compressor into unload operation, while when the selection switch is released, unload operation is disabled by high pressure control. be.

(Means for Solving the Problems) That is, the present invention provides a compressor with an unloader device that can be switched between activation and deactivation by excitation and demagnetization of a solenoid, and a refrigerating device as a safety device for the compressor. A high-pressure switch for high-pressure control with a set pressure adjusted lower than that of the high-pressure switch installed in the device is provided on the high-pressure side of the refrigeration device, and a selection switch for the unloader device and a high-pressure control switch are provided for the high-pressure control. The invention is characterized in that a circuit in which the high-pressure switch and the solenoid are connected in series is attached to the electric circuit of the refrigeration system.

(Example) Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

Figure 1 shows the basic refrigeration circuit of the refrigeration system of the present invention, which consists of a compressor 1, an air-cooled condenser 4, a liquid receiver, a pressure-reducing expansion valve 6, and a water-cooled evaporator 7. A known refrigerant circulation circuit as shown is formed.

It constitutes an air-cooled chiller exclusively for cooling, which sends chilled water cooled by the water-cooled evaporator 7 to required locations as a cooling heat source.

In the above-mentioned refrigeration system, the equipment system for the unloader attached to the compressor 1 includes unloader devices 2 attached to at least three cylinders of the four-cylinder compressor 1.
a, 2b, 2c, the gas pipe 19 taken out from the high-pressure glass line of the compressor 1, and the three-way solenoid valve SV ₁ ,
Unloading piping 20 with SV ₂ and SV ₃ interposed respectively
a, 20b, 20c and the unloading pipe 20
a, 20b, 20c are three-way solenoid valves SV ₁ , SV ₂ ,
The return pipe 21 is connected to the suction side of the compressor 1 via the SV ₃ .

The compressor 1 reduces the capacity of the compressor 1 from 100% to 75%, 50%, and 25% by energizing and demagnetizing the solenoid for the three-way solenoid valves SV ₁ , SV ₂ , and SV ₃ . It is driven like a car.

The unloader device is not limited to such a multi-stage type, but can be equipped with one unloader device 2 to achieve 100% output and 75
Of course, there is no problem even if the capacity can be controlled in two stages of % output.

The refrigeration circuit is provided with a high-pressure switch 8 on the high-pressure side as a safety device, and a high-pressure switch 9 for high-pressure control in parallel.

The operation of both high pressure switches 8 and 9 is required to meet the following specific conditions.

That is, it is necessary to adjust the set pressure value of the latter high pressure switch 9 to be lower than that of the former high pressure switch (8).
Kg/ ^cm2 , the high pressure air switch 9 for high pressure control is set to 25.5Kg/ ^cm2 , so that the latter high pressure air switch 9 operates in advance when the high pressure rises. There is.

The electrical circuit of the air-cooled chiller is shown in FIG. 2.
an auxiliary relay 14 which is deenergized when any of the other safety devices (such as an overcurrent relay or a temperature fuse) 10-1 _to 10-n is actuated; The start push button switch 17 is closed and energized, and this energization is self-maintained by the normally open contact 15b, while the stop push button switch 18 is opened and deenergized, and the auxiliary relay 15 is energized. It also has an electromagnetic switch 11 for the compressor 1 motor and an electromagnetic switch 12 for the outdoor fan motor FM, which are energized when the temperature regulator 13 is closed at a high temperature.

Note that 15a is a normally open contact of the auxiliary relay 15.

The temperature regulator 13 includes four regulators 13a, 1
3b, 13c, and 13d, and the setting temperature of the regulator 13a is set to be the lowest (for example, the inlet water temperature is 5° C.), and then the temperature is set to become higher in the following order. That is, the temperature of the regulator 13b is 7°C, and the temperature of the regulator 13c is 9°C.
℃, controller 13d is 11℃.

Therefore, the closing contact of the regulator 13a at high temperature is an electromagnetic switch 12 for the outdoor fan motor FM.
However, the three-way solenoid valves SV ₁ , SV ₂ , SV ₃ are used as the closing contacts of the regulators 13b, 13c, and 13d at low temperatures.
Solenoids 3a, 3b, and 3c are connected to each other.

In addition to the above circuit, the present invention is equipped with a high pressure control circuit, which includes a selection switch 16, a high pressure switch 9 for high pressure control, and a solenoid 3a of the unloader solenoid valve _SV1 . These devices 16, 9, and 3a are connected in series in order to form a circuit connected in parallel to the automatic start/stop circuit for the compressor motor and fan motor FM described above.

The high pressure switch 9 for high pressure control is a normally open switch that opens below the set pressure value and closes when the set pressure exceeds the set pressure value, while the selection switch 16 closes when high pressure control is required. This is a single-pole, single-throw switch.

The operating mode of the air-cooled chiller with the above configuration will be explained next.

First, let's compare the relationship between the discharge pressure and the outside air temperature when the standard water volume of the model used and the water volume at the outlet of the evaporator 7 is at an appropriate temperature, for example, 7°C, at 100% loading and unloading (75% loading). The third case is
A diagram is drawn as shown in the figure, and the operating value of the high-pressure switch 8 for safety equipment, and the operating value and return value of the high-pressure switch 9 for high-pressure control are placed on the diagram.

The operation will be described with reference to FIG. 3 obtained in this manner. First, when the outside temperature is high, close the selection switch 16 in advance.
Then, the start push button switch 17 is closed to start operation. If you operate the refrigeration equipment when the outside air temperature is low, the discharge output will be low, so it will start operating in the state shown on the graph at 100% load, but after the outside air temperature gradually rises, high pressure control will start. When the high-pressure switch 9 detects a discharge output of 25.5 Kg/cm ² and closes, the solenoid 3a of the three-way solenoid valve SV ₁ is energized, and the compressor 1 is switched to, for example, 75% load. Since the discharge output decreases, continued operation is performed with reduced capacity.

Even if the outside temperature rises further, the refrigeration system continues to operate at 75% load, resulting in the state shown below.

In this way, even if the outside air temperature rises, the high pressure will not rise abnormally and stable operation will continue. Then, when the outside temperature decreases, the state shifts to →, and when the high pressure switch 9 reaches the return point, the solenoid 3a of the three-way solenoid valve SV ₁ is demagnetized, and the refrigeration system returns to 100% load. Since it switches automatically, you can shift to the → state and continue stable operation in the same way.

According to the operation explanation described above, the operable area is
In the conventional case where the present invention is not implemented, the limit was set at an outside temperature of about 52°C, but with the device of the present invention, the limit point is widened to an outside temperature of 52°C to 56°C, and it is clear that the operable range can be expanded. It shows that.

On the other hand, during periods when the outside temperature does not rise abnormally, the selection switch 16 is opened in advance to perform normal cooling operation. In this case, even if the outside air temperature rises to 49° C., the high pressure will only rise to 26 kg/cm ² , and the compressor 1 will perform at 100% capacity and continue normal operation.

In particular, since the high pressure switch 9 for high pressure control has a predetermined pressure difference between the operating pressure and the return pressure as described above, once the unloader device is activated, the high pressure will drop to the return pressure. During this time, the compressor 1 is operated at 75% capacity, which poses a problem in terms of capacity. However, if the selection switch 16 is opened in advance, this problem can be resolved. It is.

Note that this refrigeration system is capable of unloading operation regardless of the outside temperature. That is, when the inlet water temperature of the evaporator 7 drops to 11° C. or lower, the regulator 13d closes, the solenoid 3a of the three-way solenoid valve SV ₁ is energized, and the unloader operation is switched to 75%. Furthermore, when the inlet water temperature drops below 9℃, the three-way solenoid valve
Solenoid 3b of SV ₂ is energized and changes to 50% unload operation. In this way, unloading operation is performed regardless of the outside temperature.

Further, in this embodiment, a water-cooled evaporator 7 that generates cold water is used, but it goes without saying that an air-cooled evaporator may be used instead.

(Effects of the invention) As is clear from the above explanation, the present invention connects the unloader device 2a to the compressor 1, which can be switched on and off by excitation and demagnetization of the solenoid 3a.
In addition, as a safety device for the compressor 1, the refrigeration equipment is equipped with a high-pressure control high-pressure switch 9 whose set pressure value is adjusted lower than that of the high-pressure pressure switch 8 provided in the refrigeration equipment. While the selection switch 16 of the unloader device, the high pressure switch 9 for high pressure control, and the solenoid 3a are connected in series, the circuit is attached to the electrical circuit of the refrigeration device. Selection switch 1
If the unloader device 2a is closed, even if the outside air temperature rises and the high pressure increases, the unloader device 2a
It is possible to continue operation with the capacity of the compressor forcibly reduced by activating the compressor, and it is also possible to maintain the high pressure within a range that does not activate the high pressure switch 8 for the safety device. It is possible to expand the possible range and provide a device that can withstand use even in high-temperature areas.

Moreover, by opening the selection switch 16,
Since the circuit of the unloader device 2a can be switched to non-operation, it is possible to operate with 100% compression function adapted to low outside temperature conditions, and the durability of the refrigeration device can be improved.

[Brief explanation of the drawing]

FIG. 1 is a refrigeration circuit diagram of an example of the device of the present invention, FIG. 2 is an exploded view of the main parts of the electric circuit, and FIG. 3 is an operating characteristic diagram of the device of the present invention. 1... Compressor, 2a... Unloader device, 3a
... Solenoid, 8 ... High pressure switch for safety equipment, 9 ... High pressure switch for high pressure control, 16
...Selection switch.

Claims (1)

[Scope of utility model registration request] The compressor 1 is equipped with an unloader device 2a that can be switched between activated and immovable by the excitation and demagnetization operations of the solenoid 3a. A high-pressure switch 9 for high-pressure control whose set pressure value is adjusted to a low value is provided on the high-pressure side of the refrigeration system, and a selection switch 1 for the unloader system is installed.
6, the high-pressure switch 9 for high-pressure control, and the solenoid 3a are connected in series, and a circuit is attached to the electric circuit of the refrigeration system.