JPH0571807A - Capacity controller for refrigerating plant - Google Patents

Abstract

PURPOSE:To maintain the step value of a compressor to the change of conditions while using a totally-enclosed type compressor, and to keep the control precision of the object to be cooled of the evaporator of a refrigerating plant. CONSTITUTION:A hot gas bypass 7 is installed between the discharge pipe of a refrigerant circuit 6 and the inlet-side liquid pipe of an evaporator 4, and a decompression- degree adjusting mechanism 8, in which a plurality of pairs composed of decompression mechanisms Cn and on-off valves Rn connected in series with the mechanisms Cn are connected in parallel mutually, is mounted to the hot gas bypass 7. Each on-off valve Rn of the capacity adjusting mechanism 8 is opened and closed in response to required capacity by a capacity control means 20, and the capacity of a compressor 1 is controlled at a plurality of steps. When an outside air temperature, etc., is decreased or when the pressure on the higher pressure side is lowered, the opening of the on-off valves Rn by the capacity control means 20 are changed over in the direction that the quantity of a hot gas bypassed is increased by a changeover means 21. Accordingly, a capacity value at the step of the compressor 1 is maintained under a proper state, and the control precision of an object to be cooled is kept excellent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation controller for a refrigerating machine, and more particularly to an improvement of a compressor which controls a capacity of a compressor by a hot gas bypass.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Utility Model Laid-Open No. Sho 49-4004
As disclosed in Japanese Patent Publication No. 7, in a refrigeration system including a refrigerant circuit in which a compressor, a condenser, a pressure reducing valve, and an evaporator are sequentially connected, and an evaporator cools a cooling liquid in a chiller circuit, A hot gas bypass path for bypass-connecting the discharge line of the refrigerant circuit and the liquid pipe between the pressure reducing valve and the evaporator is provided, and a heat exchanger for exchanging heat with the refrigerant of the evaporator is provided in the hot gas bypass path. By doing so, it is possible to facilitate the adjustment of the hot gas bypass amount, and thus it is a well-known technique to smoothly perform the capacity control even when using a low capacity compressor such as a fully closed compressor. is there.

[0003]

By the way, in recent years,
As the teaching ring unit is used for industrial purposes, it is required to control the outlet water temperature with high accuracy. Here, especially for medium to large units,
With a compressor equipped with multiple unload steps, it is possible to control the evaporator outlet water temperature, but with a small fully enclosed compressor, the unload steps cannot be increased. It was difficult to keep the outlet water temperature constant.

In this case, as a means for adjusting the evaporator outlet water temperature of the cooling liquid without depending on the capacity control of the compressor, for example, a heater for heating the cooling liquid is provided at the evaporator outlet, and the cooling liquid once cooled is provided. It is possible to control the water temperature at the outlet of the evaporator at a constant level by adjusting the heating amount of. But,
In that case, since the cooling liquid is once excessively cooled and the heater power is used, the efficiency becomes very poor.

Therefore, as in the above-mentioned conventional publication,
It is conceivable to adjust the capacity of the evaporator by a hot gas bypass instead of the capacity of the compressor. However, in the above publication, overheating of the refrigerant bypassed by heat exchange with the refrigerant of the evaporator in the hot gas bypass passage. Even if the refrigerant state such as the degree can be maintained properly, the change in capacity is too large when the hot gas bypass passage is opened and when it is closed,
There is a problem that it is difficult to control the water temperature at the outlet of the evaporator at a constant level. On the other hand, an electric expansion valve may be arranged in the bypass passage or a three-way valve may be arranged at a branch point from the bypass passage to control the bypass amount of the refrigerant by PID, but the controller becomes expensive.

It is also conceivable to connect a plurality of sets of an on-off valve and a capillary tube connected in series to the hot gas bypass line in parallel with each other, and control so as to open individually according to the required capacity. Even when the same on-off valve is opened, the hot gas bypass amount changes greatly depending on the pressure condition of the refrigerant circuit, and as a result, the capacity of the compressor changes, which deteriorates the control function. And such a problem is not limited to the chilling unit,
For example, air conditioners that perform cooling annually are also caused.

The present invention has been made in view of the above problems, and an object of the present invention is to arrange a plurality of sets of capillaries and an on-off valve in parallel in a hot gas bypass passage and to adjust the pressure of a refrigerant circuit. It is intended to improve the capacity control accuracy of the compressor by switching the opening / closing control of the opening / closing valve according to the change of the conditions that affect.

[0008]

In order to achieve the above object, the means taken by the invention of claim 1 is, as shown in FIG. 1, a compressor (1), a condenser (2), a main pressure reducing mechanism (3). ) And an evaporator (4) are sequentially connected, and a refrigerating device provided with a refrigerant circuit (6) is assumed.

Then, as an operation control device of the refrigeration system,
The discharge pipe of the refrigerant circuit (6) and the liquid pipe between the main decompression mechanism (3) and the evaporator (4) are connected by bypass to a hot gas bypass passage (7) and the hot gas bypass passage (7). A decompression degree adjusting mechanism (8) which is provided with a plurality of sets of decompression mechanisms (Cn) (n = 1, 2, ...) And on-off valves (Rn) serially connected to the decompression mechanisms connected in parallel with each other. And each opening / closing valve (Rn) of the above-mentioned decompression degree adjusting mechanism (8) is individually opened according to the required capacity of the evaporator (4) side which is the utilization side heat exchanger, and the capacity of the compressor (1) is changed. A capacity control means (20) for controlling a plurality of steps is provided.

Further, the heat medium temperature detecting means (Tha) for detecting the temperature of the heat medium on the heat source side of the condenser (2) which is the heat exchanger on the heat source side, and the output of the heat medium temperature detecting means (Tha) are received. When the temperature of the heat medium on the heat source side becomes equal to or lower than a certain temperature, there is provided switching means (21A) for switching the on-off valve (Rn) opened by the capacity control means (20) so as to increase the hot gas bypass amount in each step. Is provided.

As shown in FIG. 4, the means taken by the invention of claim 2 presupposes a refrigerating apparatus similar to that of the invention of claim 1 above. A similar hot gas bypass passage (7), a pressure reduction degree adjusting mechanism (8), and a capacity control means (20) are provided. Then, the high pressure detecting means (HP) for detecting the high pressure side pressure and the output of the high pressure detecting means (HP) are received, and when the high pressure side pressure becomes equal to or lower than a certain pressure, the hot gas bypass amount in each step is increased. Thus, the switching means (21B) for switching the on-off valve (Rn) opened by the capacity control means (20) is provided.

As shown in FIG. 5, the means taken by the invention of claim 3 is that a compressor (1), a condenser (2), a main decompression mechanism (3) and an evaporator (4) are sequentially connected. The refrigerating apparatus provided with the refrigerant circuit (6) is

As an operation control device for the refrigeration system,
The discharge pipe of the refrigerant circuit (6) and the liquid pipe between the main decompression mechanism (3) and the evaporator (4) are connected by bypass to a hot gas bypass passage (7) and the hot gas bypass passage (7). A decompression degree adjusting mechanism (8) which is provided with a plurality of sets of decompression mechanisms (Cn) (n = 1, 2, ...) And on-off valves (Rn) serially connected to the decompression mechanisms connected in parallel with each other. According to the required capacity on the side of the evaporator (4) serving as the heat exchanger on the use side, the opening / closing valves (Rn) of the pressure reduction degree adjusting mechanisms (8) are individually opened to make the compressor (1) have a plurality of capacities. And a capacity control means (20) for controlling the above step.

Further, the hot gas bypass passage (7)
A pressure reduction degree switching mechanism (9) including an on-off valve (R0) and a pressure reduction mechanism (C0) that are connected in series to the pressure reduction degree adjustment mechanism (8) in parallel, and the refrigerant circuit. The differential pressure detection means (HLP) for detecting when the differential pressure between the high-pressure side pressure and the low-pressure side pressure of (6) is below a certain value, and the output of the differential pressure detection means (HLP), the differential pressure is constant. When it is lower than the value, the on-off valve (R0) of the pressure reduction degree switching mechanism (9)
On the other hand, a switching means (21C) for switching the opening / closing valve (R0) of the decompression degree switching mechanism (9) to be closed when the differential pressure exceeds a certain value.

As shown in FIG. 7, the means taken by the invention of claim 4 presupposes a refrigerating apparatus similar to that of the invention of claim 3 above. A similar hot gas bypass passage (7), a pressure reduction degree adjusting mechanism (8), and a capacity control means (20) are provided. Then, in the hot gas bypass passage (7), a degree of pressure reduction including an on-off valve (R0) and a pressure reduction mechanism (C0) connected in series to the pressure reduction degree adjustment mechanism (8) and connected in parallel with each other. A switching mechanism (9), a heat medium temperature detecting means (Tha) for detecting the temperature of the heat medium on the heat source side of the condenser (2),
The output of the setting means (22) for setting the control target value of the outlet temperature of the use side heat medium to be cooled by the evaporator (4) and the heat medium temperature detecting means (Tha) is received, and the decompression is normally performed. The opening / closing valve (R0) of the temperature switching mechanism (9) is opened, while the temperature of the heat source side heat medium is equal to or higher than a certain temperature, and the control target temperature of the outlet temperature of the use side heat medium set by the setting means (22) is set. And a switching means (21D) for switching the opening / closing valve (R0) of the decompression degree switching mechanism (9) to be closed when is below a predetermined temperature.

As shown in FIG. 8, the means taken by the invention of claim 5 presupposes the same refrigerating apparatus as that of the invention of claim 3, and the operation control device of the refrigerating apparatus is the same as that of claim 3. A similar hot gas bypass passage (7), a pressure reduction degree adjusting mechanism (8), and a capacity control means (20) are provided. Then, in the hot gas bypass passage (7), a degree of pressure reduction including an on-off valve (R0) and a pressure reduction mechanism (C0) connected in series to the pressure reduction degree adjustment mechanism (8) and connected in parallel with each other. When the switching mechanism (9), the high pressure detecting means (HP) for detecting the high pressure side pressure of the refrigerant circuit (6), and the output of the high pressure detecting means (HP), the high pressure side pressure is lower than a certain value. Open / close valve (R0) of the pressure reduction degree switching mechanism (9)
On the other hand, when the high-pressure side pressure is equal to or higher than a certain value, switching means (21E) for switching to close the on-off valve (R0) of the pressure reduction degree switching mechanism (9) is provided.

[0017]

With the above construction, in the invention of claim 1, the temperature of the heat medium on the condenser (2) side (for example, the outside air temperature in the refrigerating apparatus for cooling) is lower than that under normal conditions, and the hot gas bypass passage ( When the hot gas bypass amount of 7) is about to be reduced, the switching means (21A) switches the open / close valve (Rn) that is opened in each step so as to increase the hot gas bypass amount. The reduction of the hot gas bypass amount in each step is prevented, and the capacity value in each step of the compressor (1) is maintained in the same proper state as the value under normal conditions.

According to the second aspect of the invention, when the high-pressure side pressure falls below the normal condition, the switching means (21B) causes the switching valve (Rn) opened by the capacity control means (20) to increase the hot gas bypass amount. Since the hot gas bypass amount is prevented from being reduced, the capacity value of each step of the compressor (1) is maintained in an appropriate state by the same action as that of the invention of claim 1.

In the third aspect of the invention, the opening / closing valve (R0) of the decompression degree switching mechanism (9) is opened under normal conditions, and the decompression degree adjusting mechanism (8) is opened and closed by the capacity control means (20). The capacity of the compressor (1) is step-controlled in accordance with the degree of pressure reduction which is determined by opening and closing each on-off valve (Rn).

When the pressure difference between the refrigerant circuit (6) and the refrigerant circuit (6) increases due to changes in operating conditions, the switching means (21C) closes the on-off valve (R0) of the pressure reduction degree switching mechanism (9). The degree of pressure reduction of the entire bypass passage (7) increases, the bypass amount of the hot gas bypass passage (7) is prevented from increasing, and the capacity value in each step of the compressor (1) is maintained in an appropriate state. ..

In the fourth aspect of the invention, as in the third aspect of the invention, under normal conditions, the pressure reducing degree control of the pressure reducing degree adjusting mechanism (8) by the capacity controlling means (20) controls the compressor (1). While the capacity is controlled, the heat source side heat medium temperature of the condenser (2) is high, and the control target temperature of the use side heat medium temperature of the evaporator (4) is low. The switching means (21D) closes the on-off valve (R0) of the decompression degree switching mechanism (9), so that the decompression degree of the entire hot gas bypass passage (7) increases, and the above-mentioned claim 3
By the operation similar to that of the invention described above, the capacity value in each step of the compressor (1) is maintained in an appropriate state.

In the fifth aspect of the invention, the opening / closing valve (R0) of the decompression degree switching mechanism (9) is opened under normal conditions, and the capacity of the compressor (1) is reduced by the capacity control means (20). While the opening / closing valve (Rn) of the adjusting mechanism (8) is controlled to a predetermined step value according to opening / closing, when the high-pressure side pressure exceeds a certain pressure, the switching means (21E) causes the decompression degree switching mechanism ( Since the on-off valve (R0) of 9) is closed, the degree of pressure reduction of the entire hot gas bypass passage (7) is increased, and each step of the compressor (1) is performed by the same action as the invention of claim 3 or 4. The capacitance value at is maintained in a proper state.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment corresponding to the invention of claim 1
Will be described. FIG. 1 shows a refrigerant piping system of a liquid cooling device according to a first embodiment. The liquid cooling device includes a chilling unit (B) for cooling a machine tool and a circulating liquid of the chilling unit (B). A refrigerating device (A) for cooling. The refrigeration system (A) is a fully-closed compressor (1), a condenser (2) for condensing and liquefying the refrigerant discharged from the compressor (1), and the condenser (2). A main capillary tube (3) as a depressurizing mechanism for depressurizing the refrigerant liquefied in step 1, and an evaporator (4) for evaporating the refrigerant depressurized by the main capillary tube (3) are connected to a refrigerant pipe (5 ), The refrigerant circuit (6) sequentially connected. Further, there is provided a hot gas bypass passage (7) for bypass connection between the discharge line of the refrigerant circuit (6) and the liquid pipe between the capillary tube (3) and the evaporator (4). In the hot gas bypass (7),
A decompression degree adjusting mechanism (8) for adjusting the hot gas bypass amount is provided. The decompression degree adjusting mechanism (8)
An on-off valve (Rn) (n = 1 to 3) connected in series and a capillary tube (Cn) (n = 1 to 3) as a pressure reducing mechanism.
It has multiple pairs of. And each capillary
The pipe diameters of the tubes (C1) to (C3) are set so as to become smaller in order, that is, the pressure reduction degree is sequentially increased from the first capillary tube (C1) to the third capillary tube (C3). ing. That is, the decompression degree adjusting mechanism (8)
By individually opening the first to third on-off valves (R1) to (R3), the hot gas bypass amount is adjusted by the first to third capillary tubes (C1) to (C3) having different degrees of pressure reduction. Is designed to do.

Here, the chiller circuit (10) of the chilling unit (B) is provided in the utilization medium circulating portion of the evaporator (4).
The cooling liquid circulated in the refrigerant circuit (6) is circulated, and the cold heat given in the condenser (2) in the refrigerant circuit (6) is given to the cooling liquid by heat exchange in the evaporator (4), and the cooling liquid is given. It is designed to cool.

At the outlet of the evaporator (4) of the chiller circuit (10), an outlet water temperature sensor (Thw) for detecting the water temperature Two at the outlet of the cooling water evaporator (4) is arranged. The signal of the sensor (Thw) can be input to the controller (20) that controls the operation of the refrigeration system (A).
Further, in the controller (20), a setting circuit (22) for setting a control target value Tws for the outlet temperature Two of the cooling water.
The control target temperature Tws set by the setting circuit (22) is compared with the outlet water temperature Two detected by the outlet water temperature sensor (Thw) by the controller (20), and the difference temperature is calculated. By controlling the opening and closing of each of the on-off valves (R1) to (R3) of the decompression degree adjusting mechanism (8) of the hot gas bypass passage (7) according to the corresponding required capacity,
The capacity of the compressor (1) is controlled in a plurality of steps as described below, and the controller (20) is
Has a function as a capacity control means in the invention of each claim.

Next, on the air inlet side of the condenser (2), an outside air temperature sensor (Tha) as heat medium temperature detecting means for detecting the temperature of the outside air which is the heat medium on the condenser (2) side.
Is arranged, and the signal of the outside air temperature sensor (Tha) can be input to a switching circuit (21A) as a switching means built in the controller (20).

The opening / closing control of each of the opening / closing valves (R1) to (R3) of the pressure reducing degree adjusting mechanism (8) by the controller (20) and the switching circuit (21A) will be described with reference to Tables 1 and 2 below. To do.

[0029]

[Table 1]

[0030]

[Table 2]

Table 1 shows the case of control under normal conditions, and Table 2 shows control when the outside air temperature is below a certain temperature (for example, a temperature of about 13 ° C.), that is, when the outside air is low. That is, under normal conditions, the capacity of the compressor (1) is increased to 80% by opening the third opening / closing valve (R3), and the second opening / closing valve (R3) is opened.
By opening 2), the capacity of the compressor (1) is increased to 60%,
The capacity of the compressor (1) is made 40% by opening the first on-off valve (R1), and combined with 100% by closing all the on-off valves (R1) to (R3), the compressor (1) The capacity is controlled in four steps.

On the other hand, under low outside air conditions, the compressor (1) is opened by opening the second and third on-off valves (R2), (R3).
Capacity of 80%, the first and third on-off valves (R1), (R
By opening 3), the capacity of the compressor (1) becomes 60%,
Open / close control of the open / close valves (R1) to (R3) under the above normal conditions so that the capacity of the compressor (1) is set to 40% by opening the first and second open / close valves (R1) and (R2). I am trying to make it different from. That is, when the outside air is low, the number of open / close valves is increased to compensate for the reduction in the hot gas bypass amount, and the capacity control of the compressor (1) is controlled in four steps with the same capacity as under normal conditions. There is.

Therefore, in the first embodiment, in the refrigeration system (A), the refrigerant discharged from the compressor is condensed and liquefied by the condenser (2) and then decompressed by the main capillary tube (3). By circulating so as to return to the compressor (1) evaporated in the evaporator (4), cold heat obtained by heat exchange with the outdoor air is applied to the cooling liquid of the chilling unit (B) by the condenser (2). .. The controller (20) serving as a capacity control means compares the outlet water temperature Two of the cooling liquid detected by the outlet water temperature sensor (Thw) of the evaporator (4) with the set temperature Tws, and the outlet water temperature Two is set. T
Each open / close valve (R1) of the pressure reduction degree adjusting mechanism (8) is designed so that the capacity of the compressor (1) is increased as the value is higher than ws and is decreased as the temperature approaches the set temperature Tws. (R
3) individually open the capacity of the compressor (1) to 100%,
The outlet water temperature Two is finely controlled by controlling in four steps of 80%, 60% and 40% (see FIG. 2).

At this time, when the outside air temperature detected by the outside air temperature sensor (Tha) is below a certain temperature, the high-pressure side pressure decreases, so the amount of hot gas bypass from the hot gas bypass passage (7) decreases, When the opening / closing control of the opening / closing valves (R1) to (R3) is performed under the same conditions as under normal conditions, the actual capacity of the compressor (1) is 80%,
The values are higher than 60% and 40%, respectively, and the capacity difference between the steps deviates from the proper value by a large amount (see, for example, FIG. 3).

On the other hand, in the first embodiment, when the outside air is low, the number of open operations of the opening / closing valves (R1) to (R3) of the pressure reduction degree adjusting mechanism (21A) at each step is increased to increase the hot gas bypass amount. Therefore, the reduction of the hot gas bypass amount in each step is compensated, and the capacity value of the compressor (1) substantially equal to the capacity value of each step in the normal control as shown in FIG. 2 is secured. Will be. That is, it is possible to improve the control accuracy of the outlet water temperature Two while using an inexpensive fully-closed compressor.

Next, a second embodiment corresponding to the invention of claim 2
Will be described. FIG. 4 shows the piping system of the refrigeration system (A) and the chilling unit (B) in Example 2,
The piping system is the same as the piping system of the first embodiment shown in FIG. 1, but in this embodiment, instead of the outside air temperature sensor (Tha), a high pressure sensor (HP) as a high pressure detecting means for detecting the high pressure side pressure. Is disposed in the discharge pipe.

Then, in the present embodiment, the opening / closing control shown in Table 1 of the above-described Embodiment 1 is performed for each of the opening / closing valves (R1) to (R3) of the decompression degree adjusting mechanism (8) under normal conditions.
When the high-pressure side pressure falls below a certain pressure (for example, a pressure value of about 13 kg / cm ² ), the switching circuit (21B) in the controller (8) switches to the same opening / closing control as shown in Table 2 of the first embodiment. Has been done.

Therefore, also in the second embodiment, the hot gas bypass amount is reduced by decreasing the high-pressure side pressure so as to increase the number of open operations of the opening / closing valves (R1) to (R3) of the pressure reduction degree adjusting mechanism (8). It is possible to compensate by switching and properly maintain the capacity value in each step of the compressor (1). That is, it is possible to obtain the same effect as that of the first embodiment.

Next, a third embodiment corresponding to the invention of claim 3
Will be described. FIG. 5 shows the piping system of the refrigeration system (A) and the chilling unit (B) in Example 3,
In addition to the same configuration as that of the piping system shown in FIG. 1 of the first embodiment, in the present embodiment, in the hot gas bypass passage (7), the pressure reduction degree switching mechanism (9) is connected in series with the pressure reduction degree adjusting mechanism (8). Is provided. The decompression degree adjusting mechanism (9)
A switching capillary tube (C0) having a small pipe diameter, that is, a large degree of pressure reduction and a switching on-off valve (R0) are arranged in parallel. That is, by opening and closing the switching on-off valve (R0), the compressor (1) by the pressure reduction degree adjusting mechanism (8).
The step control pattern of is switched to two modes.

Further, in place of the outside air temperature sensor (Tha), a differential pressure switch (HLP) is provided which is activated when the high and low differential pressure value becomes a certain value (for example, a value of about 10 kg / cm ² ) or less. When the differential pressure switch (HLP) is not operated by the switching circuit (21C) in the controller (8), the switching opening / closing valve (C) of the pressure reduction degree switching mechanism (9) is
0) is closed while the differential pressure switch (HLP) is activated, the switching on-off valve (C0) is opened and closed. That is, in this embodiment, the switching circuit (21C) constitutes the switching means according to the invention of claim 3.

Therefore, in the third embodiment, the switching circuit (21C) causes the switching opening / closing valve (R0) of the pressure reduction degree switching mechanism (9) to operate when the high and low differential pressure detected by the differential pressure switch (HLP) is small. While opening, the high and low differential pressure increases due to changes in operating conditions, resulting in a constant value (10 kg / cm in the above embodiment).
² ) When the above is reached, the switching on-off valve (R0) is controlled to be closed, and by this control, the degree of pressure reduction of the entire hot gas bypass passage (7) is increased and the hot gas bypass amount is reduced.

That is, when the degree of pressure reduction of the entire hot gas bypass passage (7) is constant, and when the high and low differential pressure is small,
As shown in FIG. 2 in the first embodiment, the compressor (1)
The capacity is controlled in four steps of 100%, 80%, 60, and 40%, but when the high and low differential pressure increases, the hot gas bypass amount from the hot gas bypass passage (7) increases, so that As shown in, the capacity value of the compressor (1) is a value deviating from the proper state such as 100%, 50%, 20%, 10%, and the difference between the maximum capacity value and the capacity value of another step. Becomes too large, and as a result, the control accuracy of the outlet water temperature Two deteriorates.

On the other hand, as described above, by controlling the switching on-off valve (R0) to be closed when the high and low differential pressure increases, the actual capacity of each step of the compressor (1) is almost as shown in FIG. Such an appropriate value and the outlet water temperature T
It is possible to prevent the deterioration of the control accuracy of wo.

Next, a fourth embodiment corresponding to the invention of claim 4
Will be described. As shown in FIG. 7, the refrigeration system (A) and the chilling unit (B) in this embodiment have the same circuit configuration as that of the third embodiment, but in this embodiment, the differential pressure switch (HLP) is used. Instead of the above, an outside air temperature sensor (Tha) is attached to the air suction port of the condenser (2), and its signal is connected to the controller (20) so that it can be input. Then, when the outside air temperature detected by the outside air temperature sensor (Tha) is lower than a constant temperature (for example, 23 ° C.) by the switching circuit (21D) in the controller (20), the pressure reduction degree switching mechanism (9) is opened and closed. While opening the valve (R0), the control target temperature Tws of the outlet water temperature set by the setting circuit (22) is a constant value (for example, a value of about 15 ° C).
In the following cases, when the outside air temperature exceeds a certain temperature, the switching on-off valve (R0) is closed and the hot gas bypass passage (7) is closed.
It is controlled so as to increase the overall degree of pressure reduction and reduce the amount of hot gas bypass. That is, the switching circuit (21D)
Functions as the switching means in the invention of claim 4.

Here, the outside air temperature is high and the evaporator (4)
Under the condition that the outlet water temperature is low, that is, the high-pressure side pressure is high and the low-pressure side pressure is low, the high-low differential pressure is large, as described in the third embodiment, the compressor (1 ) The capacity value in each step becomes smaller than the appropriate value, and the control accuracy of the outlet water temperature Two may deteriorate (see FIG. 6). However, in the fourth embodiment, the switching circuit (21D) causes Decompression degree switching mechanism (9)
The on-off valve (R1) is closed and the hot gas bypass amount is reduced. Therefore, the capacity value in each step of the compressor (1) is maintained in a proper state as shown in FIG. 2, and deterioration of the control accuracy of the outlet water temperature Two is prevented.

Next, a fifth embodiment corresponding to the invention of claim 5
Will be described. As shown in FIG. 8, the piping configurations of the refrigeration system (A) and the chilling unit (B) of this example are as follows.
5 is the same as that shown in FIG. 5 in the third embodiment, but a high pressure pressure sensor (HP) is provided instead of the differential pressure switch (HLP), and its signal is a switching circuit (21E) in the controller (20). ) Has been made possible to enter. When the high-pressure side pressure is equal to or lower than a certain pressure (for example, a pressure value of about 13 kg / cm ² ), the switching on-off valve (R0) of the pressure reduction degree switching mechanism (9) is opened, while the high-pressure side pressure exceeds the certain pressure. Then, the switching on-off valve (R0) is closed to increase the degree of pressure reduction of the entire hot gas bypass passage (7) and reduce the hot gas bypass amount. The switching circuit (21E) functions as the switching means in the invention of claim 5.

That is, also in this embodiment, when the pressure on the high pressure side increases, the switching on-off valve (R) of the decompression degree switching mechanism (9) is changed.
By closing 0), the hot gas bypass amount is reduced. Therefore, as in the third or fourth embodiment,
The capacity value in each step of the compressor (1) can be maintained in an appropriate state, and deterioration of the control accuracy of the outlet water temperature Two can be prevented.

In each of the above embodiments, the refrigeration system (A)
Is for cooling the cooling water of the chilling unit (B), but the present invention is not limited to such an embodiment, and can be applied to an air conditioner for cooling the room. ..

Further, in each of the above-mentioned embodiments, the pressure reduction degree of each capillary tube (C1) to (C3) of the pressure reduction degree adjusting mechanism (8) is set to a different value, but each capillary tube (C1) is not always required. ) To (3) need not be different, and may be exactly the same.

[0050]

As described above, according to the invention of claim 1, as the operation control device of the refrigeration system, the discharge pipe and the pressure reducing mechanism of the refrigerant circuit and the liquid pipe between the evaporator are formed by the hot gas bypass passage. By providing a bypass connection, a hot gas bypass passage is provided with a pressure reducing degree adjusting mechanism in which a plurality of groups of a pressure reducing mechanism and an on-off valve connected in series to the hot pressure bypass mechanism are connected in parallel to each other, depending on the required capacity of the evaporator side. Controlling the opening and closing of each on-off valve of the decompression degree adjusting mechanism, and switching the on-off valve to the direction in which the hot gas bypass amount increases when the temperature of the heat source side heat medium of the condenser falls below a certain temperature. As a result, it is possible to prevent the capacity value of each step of the compressor from deviating from the proper state due to the reduction of the hot gas bypass amount. evil The without incurring, it is possible to satisfactorily maintain the control accuracy of the outlet temperature of the usage-side medium to be cooled in the evaporator.

According to the invention of claim 2, as the operation control device of the refrigeration system, the discharge pipe and the liquid pipe between the pressure reducing mechanism of the refrigerant circuit and the evaporator are bypass-connected by the hot gas bypass passage,
The hot gas bypass path is equipped with a decompression degree adjustment mechanism that connects multiple groups of decompression mechanisms and on-off valves connected in series with each other in parallel, and adjusts the decompression degree according to the required capacity of the evaporator side. It controls opening / closing of each on-off valve of the mechanism, and when the high-pressure side pressure falls below a certain pressure, the opening / closing valve is switched to increase / decrease the hot gas bypass amount. It is possible to prevent the displacement of the capacity value of each step of the compressor from the proper state, and therefore, it is possible to obtain the same effect as that of the invention of claim 1 above.

According to the invention of claim 3, as the operation control device of the refrigeration system, the discharge pipe and the pressure reducing mechanism of the refrigerant circuit-the liquid pipe between the evaporators are bypass-connected by the hot gas bypass passage.
The hot gas bypass path is equipped with a decompression degree adjustment mechanism that connects multiple groups of decompression mechanisms and on-off valves connected in series with each other in parallel, and adjusts the decompression degree according to the required capacity of the evaporator side. While controlling the opening and closing of each on-off valve of the mechanism, in the hot gas bypass path, a decompression degree switching mechanism in which the on-off valve and the decompression mechanism are connected in parallel is provided in series to the decompression degree adjusting mechanism, Under normal conditions, the on-off valve of the decompression degree switching mechanism is opened, while the on-off valve of the decompression degree switching mechanism is closed when the high and low differential pressure exceeds a certain level. It is possible to prevent the capacitance value from deviating from the proper state, and thus
The use of the fully-closed compressor makes it possible to maintain good cost control accuracy of the outlet temperature of the use-side medium to be cooled by the evaporator, while maintaining low cost and without degrading the coefficient of performance.

According to the invention of claim 4, as the operation control device of the refrigerating device, the discharge pipe and the pressure reducing mechanism of the refrigerant circuit-the liquid pipe between the evaporators are bypass-connected by the hot gas bypass passage,
The hot gas bypass path is equipped with a decompression degree adjustment mechanism that connects multiple groups of decompression mechanisms and on-off valves connected in series with each other in parallel, and adjusts the decompression degree according to the required capacity of the evaporator side. While controlling the opening and closing of each on-off valve of the mechanism, in the hot gas bypass path, a decompression degree switching mechanism in which the on-off valve and the decompression mechanism are connected in parallel is provided in series to the decompression degree adjusting mechanism, Under normal conditions, while opening the on-off valve of the decompression degree switching mechanism, the heat source side heat medium temperature of the condenser rises above a certain temperature and the control target temperature of the evaporator use side heat medium falls below a certain value. Under the condition of increasing differential pressure,
Since the on-off valve of the decompression degree switching mechanism is closed, it is possible to prevent the capacity value of each step of the compressor from deviating from the proper state due to the increase of the hot gas bypass amount. Therefore, the invention according to claim 3 above The same effect as can be obtained.

According to the invention of claim 5, as the operation control device of the refrigeration system, the discharge pipe and the pressure reducing mechanism of the refrigerant circuit and the liquid pipe between the evaporator are bypass-connected by the hot gas bypass passage.
In the hot gas bypass path, a decompression degree adjusting mechanism is provided in which a plurality of sets of decompression mechanism and on-off valves connected in series to this are connected in parallel to each other. In addition to controlling the opening / closing of each on-off valve, a decompression degree switching mechanism, in which an on-off valve and a decompression mechanism are connected in parallel, is installed in series with the decompression degree adjusting mechanism in the hot gas bypass line under normal conditions. Below, the on-off valve of the decompression degree switching mechanism is opened, while the on-off valve of the decompression degree switching mechanism is closed when the high-pressure side pressure rises above a certain pressure. It is possible to prevent the deviation of the capacitance value from the appropriate state, and therefore, it is possible to obtain the same effect as the invention of claim 3 above.

[Brief description of drawings]

FIG. 1 is a diagram showing a piping system and a signal path of a refrigeration system and a chilling unit according to a first embodiment.

FIG. 2 is a diagram showing the capacity value of each step of the compressor under normal conditions of the first embodiment.

FIG. 3 is a diagram showing a change in capacity value of a step of the compressor under low outside air condition when the on-off valve is opened and closed.

FIG. 4 is a diagram showing a piping system and a signal path of a refrigeration system and a chilling unit according to a second embodiment.

FIG. 5 is a diagram showing a piping system and a signal path of a refrigeration system and a chilling unit according to a third embodiment.

FIG. 6 is a diagram showing a change in capacity value at each step of the compressor under a condition of increasing differential pressure between high and low when the open / close valve is opened and closed.

FIG. 7 is a diagram showing a piping system and a signal path of a refrigeration system and a chilling unit according to a fourth embodiment.

FIG. 8 is a diagram showing a piping system and a signal path of a refrigeration system and a chilling unit according to a fifth embodiment.

[Explanation of symbols]

 1 Compressor 2 Condenser 3 Main decompression mechanism (main capillary tube) 4 Evaporator 6 Refrigerant circuit 7 Hot gas bypass passage 8 Capacity adjustment mechanism 9 Capacity switching mechanism 20 Controller (capacity control means) 21 Switching circuit (switching means) 22 Setting circuit (setting means) HP High pressure sensor (high pressure detection means) HLP Differential pressure switch (differential pressure detection means) Tha Outside air temperature sensor (heat medium temperature detection means)

Claims (5)

[Claims] 1. A refrigeration system comprising a refrigerant circuit (6) in which a compressor (1), a condenser (2), a main decompression mechanism (3) and an evaporator (4) are sequentially connected to each other. A hot gas bypass passage (7) for bypass-connecting the discharge pipe of (6) and the liquid pipe between the main decompression mechanism (3) and the evaporator (4), and the hot gas bypass passage (7), A decompression degree adjusting mechanism (8) in which a plurality of groups of a decompression mechanism (Cn) (n = 1, 2, ...) And an on-off valve (Rn) connected in series to the decompression mechanism are connected in parallel to each other. Each opening / closing valve (Rn) of the pressure reduction degree adjusting mechanism (8) is individually opened according to the required capacity on the side of the evaporator (4) serving as a side heat exchanger, and the capacity of the compressor (1) is set in a plurality of steps. A heat source side heat medium of a condenser (2) which is a heat source side heat exchanger. When the temperature of the heat medium temperature detecting means (Tha) for detecting the temperature and the output of the heat medium temperature detecting means (Tha) is received and the temperature of the heat medium on the heat source side becomes below a certain temperature, the hot gas bypass amount in each step And a switching means (21A) for switching the on-off valve (Rn) opened by the capacity control means (20) so as to increase the temperature. 2. A refrigeration system comprising a refrigerant circuit (6) in which a compressor (1), a condenser (2), a main decompression mechanism (3) and an evaporator (4) are sequentially connected, the refrigeration circuit comprising: A hot gas bypass passage (7) for bypass-connecting the discharge pipe of (6) and the liquid pipe between the main decompression mechanism (3) and the evaporator (4), and the hot gas bypass passage (7), A decompression degree adjusting mechanism (8) in which a plurality of groups of a decompression mechanism (Cn) (n = 1, 2, ...) And an on-off valve (Rn) connected in series to the decompression mechanism are connected in parallel to each other. Depending on the required capacity on the side of the evaporator (4) serving as a side heat exchanger, each opening / closing valve (Rn) of the above-mentioned pressure reduction degree adjusting mechanism (8) is individually opened to set the capacity of the compressor (1) to a plurality of steps. A high-pressure detecting means (HP) for detecting the high-pressure side pressure, and a high-capacity detecting means (HP) Receiving the output of the detection means (HP), when the high side pressure is below a predetermined pressure, the capacity control means to increase the hot gas bypass amount in each step (2
0) An operation control device for a refrigerating machine, comprising: a switching means (21B) for switching an on-off valve (Rn) opened by 0). 3. A refrigeration system comprising a refrigerant circuit (6) in which a compressor (1), a condenser (2), a main decompression mechanism (3) and an evaporator (4) are sequentially connected, the refrigeration circuit comprising: A hot gas bypass passage (7) for bypass-connecting the discharge pipe of (6) and the liquid pipe between the main decompression mechanism (3) and the evaporator (4), and the hot gas bypass passage (7), A decompression degree adjusting mechanism (8) in which a plurality of groups of a decompression mechanism (Cn) (n = 1, 2, ...) And an on-off valve (Rn) connected in series to the decompression mechanism are connected in parallel to each other. Depending on the required capacity on the side of the evaporator (4) serving as the side heat exchanger, the on-off valves (Rn) of the pressure reduction degree adjusting mechanisms (8) are individually opened to set the capacity of the compressor (1) to a plurality of steps. And a capacity control means (20) for controlling, and adjusting the degree of pressure reduction in the hot gas bypass passage (7). Decompression degree switching mechanism (9) consisting of an on-off valve (R0) and decompression mechanism (C0) connected in series to the structure (8) and connected in parallel, and the high pressure side of the refrigerant circuit (6). The differential pressure detecting means (HLP) for detecting when the differential pressure between the pressure and the low-pressure side pressure is below a certain value, and the output of the differential pressure detecting means (HLP). A switching means (21C) for switching the opening / closing valve (R0) of the pressure reduction degree switching mechanism (9) while closing the opening / closing valve (R0) of the pressure reduction degree switching mechanism (9) when the differential pressure exceeds a certain value. An operation control device for a refrigeration system, comprising: 4. A refrigeration system provided with a refrigerant circuit (6) in which a compressor (1), a condenser (2), a main decompression mechanism (3) and an evaporator (4) are sequentially connected, wherein A hot gas bypass passage (7) for bypass-connecting the discharge pipe of (6) and the liquid pipe between the main decompression mechanism (3) and the evaporator (4), and the hot gas bypass passage (7), A decompression degree adjusting mechanism (8) in which a plurality of groups of a decompression mechanism (Cn) (n = 1, 2, ...) And an on-off valve (Rn) connected in series to the decompression mechanism are connected in parallel to each other. Depending on the required capacity on the side of the evaporator (4) serving as the side heat exchanger, the on-off valves (Rn) of the pressure reduction degree adjusting mechanisms (8) are individually opened to set the capacity of the compressor (1) to a plurality of steps. And a capacity control means (20) for controlling, and adjusting the degree of pressure reduction in the hot gas bypass passage (7). A pressure reduction degree switching mechanism (9) including an on-off valve (R0) and a pressure reduction mechanism (C0) connected in series to the structure (8) and connected in parallel to each other, and a heat source side of the condenser (2). Heat medium temperature detecting means (Tha) for detecting the temperature of the heat medium, setting means (22) for setting a control target value of the outlet temperature of the use side heat medium to be cooled by the evaporator (4), and While receiving the output of the heat medium temperature detecting means (Tha), the opening / closing valve (R0) of the decompression degree switching mechanism (9) is normally opened, while the temperature of the heat medium on the heat source side is equal to or higher than a certain temperature and the setting means ( Two
When the control target temperature of the outlet temperature of the heat medium on the use side set in 2) is equal to or lower than a predetermined temperature, the decompression degree switching mechanism (9)
Switching means (21) for switching to close the on-off valve (R0) of
D) and an operation control device for a refrigerating apparatus. 5. A refrigeration system provided with a refrigerant circuit (6) in which a compressor (1), a condenser (2), a main decompression mechanism (3) and an evaporator (4) are sequentially connected, wherein A hot gas bypass passage (7) for bypass-connecting the discharge pipe of (6) and the liquid pipe between the main decompression mechanism (3) and the evaporator (4), and the hot gas bypass passage (7), A decompression degree adjusting mechanism (8) in which a plurality of groups of a decompression mechanism (Cn) (n = 1, 2, ...) And an on-off valve (Rn) connected in series to the decompression mechanism are connected in parallel to each other. Depending on the required capacity on the side of the evaporator (4) serving as the side heat exchanger, the on-off valves (Rn) of the pressure reduction degree adjusting mechanisms (8) are individually opened to set the capacity of the compressor (1) to a plurality of steps. And a capacity control means (20) for controlling, and adjusting the degree of pressure reduction in the hot gas bypass passage (7). Decompression degree switching mechanism (9) consisting of an on-off valve (R0) and decompression mechanism (C0) connected in series to the structure (8) and connected in parallel, and the high pressure side of the refrigerant circuit (6). The high pressure detecting means (HP) for detecting the pressure and the output of the high pressure detecting means (HP) are received, and when the high pressure side pressure is lower than a certain value, the opening / closing valve (R0) of the pressure reducing degree switching mechanism (9) is opened. On the other hand, when the high-pressure side pressure is equal to or higher than a certain value, there is provided a switching means (21E) for switching the opening / closing valve (R0) of the decompression degree switching mechanism (9) so as to be closed. ..