JP2500531B2 - Refrigeration system operation controller - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration system operation control device, and more particularly to a compressor capacity control measure before defrost operation.

[0002]

2. Description of the Related Art Generally, a refrigerating apparatus of this type includes a compressor, a condenser, a receiver, an expansion valve, and an evaporator, as disclosed in JP-A-59-197764. There is a structure in which a refrigerant gas line is connected in order and a hot gas bypass path that bypasses the condenser, the receiver, and the expansion valve is connected. Then, in this refrigeration system, when the frost of the evaporator is detected by an air pressure switch, a timer, etc., hot gas is made to flow from the compressor to the evaporator through the hot gas bypass passage to perform defrost operation, while suction of the compressor is taken. When the gas temperature reaches a predetermined temperature, the defrosting operation is terminated, and the defrosting operation removes the frost from the evaporator to prevent the refrigeration capacity from decreasing.

[0003]

In the above refrigerating apparatus, so-called metering defrosting is performed in which the refrigerant is metered before the defrosting operation and the defrosting operation is performed with a constant amount of the refrigerant. That is, the pump down operation is performed before the defrost operation, the refrigerant is once collected in the receiver or the like, and the defrost operation is performed by using a part of the collected refrigerant.

However, in the conventional pump down operation, since the capacity of the compressor is set to the maximum capacity, as shown in FIG. 4, the capacity of the compressor is low during the steady operation before the pump down operation. In the case of the capacity (A1), when the pump down operation (A2) is performed, the high-pressure refrigerant pressure on the compressor discharge side suddenly rises, which causes a high-pressure cut (HPS cut) (A3). Especially, the capacity of the receiver is small,
Moreover, it tends to occur when the outside air temperature is high. That is,
When the compressor has a low capacity, a large amount of the refrigerant liquid is accumulated in the receiver, and the capacity of the compressor is switched from this state to the maximum capacity, so that the discharged refrigerant gas is compressed and the high pressure is cut. When this high-pressure cut occurs, the compressor stops, so a restart operation is required, and there is a problem that smooth continuous operation cannot be performed.

The present invention has been made in view of the above circumstances, and an object thereof is to enable smooth continuous operation without causing a high pressure cut during pump down operation and to miniaturize a receiver and the like. It is what

[0006]

[Means for Solving the Problems] In order to achieve the above object, the means taken by the present invention is to reduce the capacity of the compressor at the start of the pump down operation, and thereafter to increase the capacity of the compressor. It was done like this.

Specifically, as shown in FIG. 1, the means taken by the invention according to claim 1 is as follows.
1), a condenser (12), an expansion mechanism (EV), and an evaporator (14) are sequentially connected to each other, a refrigerant circulation circuit (1).
A hot gas bypass passage (17) for supplying hot gas discharged from the compressor (11) to the evaporator (14) by bypassing at least the condenser (12), and the hot gas bypass passage (17). It is premised on a refrigeration system provided with a part of the refrigerant circulation circuit (1) that bypasses, and a liquid storage means (18) for confining the refrigerant.

A capacity control means (21) for controlling the capacity of the compressor (11) according to the load, and a liquid storage means (18) for the refrigerant when the evaporator (14) is frosted.
And a pump down control means (23) for performing a pump down operation so as to recover it. Further, there is provided a capacity changing means (24) for setting the capacity of the compressor (11) to a low capacity at the start of operation in the pump down operation of the pump down control means (23) and changing it to a high capacity after a predetermined time. There is. In addition, the pump down control means (2
After the pump down operation by 3) is completed, the liquid storage means (1
Using a part of the refrigerant of 8), the hot gas is compressed by the compressor (1
The defrost control means (22) for defrosting the hot gas bypass passage (17) is provided.

The means taken by the invention according to claim 2 is the capacity changing means (24) in the invention according to claim 1.
However, the capacity of the compressor (11) is set to the minimum capacity at the start of the pump-down operation, and is changed to the maximum capacity after a predetermined time.

[0010]

With the above construction, in the invention according to claim 1,
The refrigerant circulates in the refrigerant circulation circuit (1), cools the air sucked in the evaporator (14), and blows out the cooling air. The capacity control means (21) controls the capacity of the compressor (11) according to the load.

On the other hand, when the evaporator (14) is frosted, first, the pump down control means (23) starts the pump down operation and the pump down control means (2).
In response to the operation signal of 3), the capacity changing means (24) sets the capacity of the compressor (11) to a low capacity, and changes it to a high capacity after a predetermined time. Specifically, in the invention according to claim 2, the capacity of the compressor (11) is set to the minimum capacity in the initial stage of the pump down operation, and then changed to the maximum capacity. Then, this pump-down operation allows the refrigerant to be contained in the liquid storage means (18).

Thereafter, the defrost control means (22) utilizes a part of the refrigerant confined in the liquid storage means (18) to transfer hot gas from the compressor (11) to the hot gas bypass passage (17). To the evaporator (14) and control the defrosting operation to remove the frost from the evaporator (14).

[0013]

Therefore, according to the first aspect of the invention, the capacity of the compressor (11) is set to a low capacity at the start of the pump down operation, and then the capacity of the compressor (11) is changed to a high capacity. Therefore, when the compressor (11) is switched from the low capacity steady operation state to the pump down operation, a large amount of high pressure refrigerant gas is not discharged from the compressor (11), so high pressure cut is prevented. be able to. In particular, even when the outside air temperature is high, the high pressure cut can be prevented, so that a restart operation is not required and a smooth continuous operation can be performed.

Further, even when the refrigerant storage capacity of the liquid storage means (18) is small, the high pressure cut can be prevented, so that, for example, the capacity of the receiver can be reduced and the overall size of the apparatus can be reduced.

Further, according to the second aspect of the invention, since the capacity of the compressor (11) is set to the minimum capacity in the initial stage of the pump down operation, the high pressure cut can be performed more reliably and the receiver can be more reliable. It is possible to reduce the size.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 2, (1) is a refrigerant circulation circuit of a refrigerating apparatus provided in a refrigerating container, which cools the inside of a container body (not shown).

The refrigerant circulation circuit (1) has a capacity of 100%.
Of maximum capacity, 67% of medium capacity, and 33% of minimum capacity, a compressor (11), a condenser (12), a receiver (13), and an electric expansion valve (EV) that is an expansion mechanism. )When,
An evaporator (14), an accumulator (15), and a suction solenoid valve (SV) having a bleed port are sequentially connected by a refrigerant pipe (16) to form a closed circuit. Then, the outside fan (12) is installed in the condenser (12).
a), the inside fan (14a) is attached to the evaporator (14), and the three-way solenoid valve (TV) is interposed between the compressor (11) and the condenser (12). It is set up. One end of a hot gas bypass passage (17) is connected to the three-way solenoid valve (TV), and the other end of the hot gas bypass passage (17) is connected to the electric expansion valve (EV) and the evaporator (1).
4) and the drain pan heater (1
7a) has been formed. The hot gas bypass passage (17) supplies hot gas from the compressor (11) to the evaporator (14) during the defrost operation, and the hot gas bypass passage (17) is supplied to the evaporator (1).
4) and the frost of the drain pan (not shown) are melted.

Further, a liquid storage means (18) is provided between the condenser (12) and the electric expansion valve (EV), and between the receiver (13) and the electric expansion valve (EV). An on-off valve (WV) and a liquid reservoir (19) are provided in the container, and the liquid reservoir (19) and the receiver (13) constitute the liquid reservoir (18). Then, the pump down operation is performed before the defrost operation is performed, and the refrigerant is received by the receiver (1
3) and the liquid reservoir (19).

Further, various sensors are provided in the refrigerating apparatus, (HPS) is a high pressure sensor for detecting the high pressure refrigerant pressure on the discharge side of the compressor (11), and (Th1) is an evaporator (14). , A liquid pipe temperature sensor for detecting the liquid pipe temperature on the inlet side, (Th2) is a gas pipe temperature sensor for detecting the gas pipe temperature on the outlet side of the evaporator (14), and (Th3) is the evaporator (1
4) Suction temperature sensor for detecting the suction air temperature on the air suction side, (Th4) is a discharge temperature sensor for detecting the discharge air temperature on the air discharge side of the evaporator (14), and (Th5) is the compressor (11). Is a suction pipe temperature sensor that detects a suction gas temperature on the suction side of the.

The sensors (HPS), (Th
The detection signals of (1) to (Th5) are input to the controller (2), while the controller (2) is connected to the compressor (1).
1), an electric expansion valve (EV), a suction solenoid valve (SV), a three-way solenoid valve (TV), an opening / closing valve (WV), etc. are controlled. That is, the controller (2)
Performs PID control of the electric expansion valve (EV) by the degree of superheat based on the detection signals of the liquid pipe temperature sensor (Th1) and the gas pipe temperature sensor (Th2) in the refrigerating mode, and the outlet temperature sensor (Th4) in the refrigerating mode. PID control is performed according to the temperature of the blown air based on the detection signal, while the intake solenoid valve (SV) is controlled to close when the evaporation temperature decreases, for example, when the predetermined opening of the electric expansion valve (EV) continues for a certain period of time. are doing.

Further, the controller (2) is provided with a capacity control means (21) for the compressor (11), a defrost control means (22), a pump down control means (23), and a capacity changing means. (24) and are provided. In the refrigerating mode, the capacity control means (21) controls the compressor (1) so that the temperature inside the refrigerator, that is, the suction air temperature detected by the suction temperature sensor (Th3) becomes the set temperature.
While controlling 1) ON / OFF, in the refrigerating mode, the capacity of the compressor (11) is controlled so that the blown air temperature detected by the blowout temperature sensor (Th4) becomes a set temperature. .

The pump down control means (23)
Is a pump-down operation at the time of frost of the evaporator (14). The electric expansion valve (EV) is closed and the opening / closing valve (W
V) is opened to collect the refrigerant in the liquid reservoir (19) and the receiver (13). The capacity changing means (24) changes the capacity of the compressor (11) during pump down operation, and the first timer (T1).
And a second timer (T2). Then, the capacity changing means (24) is configured to have the first capacity when the pump down operation is started.
Until the timer (T1) counts up, the compressor (1
The capacity of 1) is set to the minimum capacity, and then the capacity of the compressor (11) is set to the maximum capacity until the second timer (T2) counts up.

On the other hand, the defrost control means (22)
When the pump down operation of the pump down control means (23) ends, the electric expansion valve (EV) is opened, the opening / closing valve (WV) is closed, and the three-way solenoid valve (TV) is switched, The refrigerant accumulated in the liquid reservoir (19) is used to supply hot gas from the compressor (11) to the evaporator (14) via the hot gas bypass passage (17) to control the defrost operation. It is configured.

Next, the operation of the refrigeration system will be described based on the control flow of FIG.

First, during steady operation, the compressor (1
The refrigerant discharged from 1) is condensed in the condenser (12), expanded by the electric expansion valve (EV), evaporated in the evaporator (14) and returned to the compressor (11), and is stored in the container body. The inside is cooled. Then, during this steady operation, the capacity control means (21) controls the capacity of the compressor (11), and during the refrigerating mode, the suction air temperature detected by the suction temperature sensor (Th3) becomes the set temperature. Compressor (1
While controlling 1) ON / OFF, in the refrigerating mode, the capacity of the compressor (11) is set to 100% and 6% so that the blown air temperature detected by the blowout temperature sensor (Th4) becomes the set temperature.
It is controlled to either 7% or 33%. When the evaporator (14) frosts during the steady operation in the refrigerating mode, the frost is detected by a timer or the like, and step ST1
And the pump down operation is started. That is, the pump down control means (23) causes the electric expansion valve (E
V) is fully closed and the open / close valve (WV) is opened, while the capacity changing means (24) causes the first timer (T1) to count and the capacity of the compressor (11) to be the minimum capacity (33%).
Set to. The first timer (T1) is set to the minimum capacity operating time of the compressor (11) and the valve closing time of the electric expansion valve (EV), for example, 10 seconds.

After that, the process proceeds to step ST2, it is determined whether or not the first timer (T1) has counted up, and the process waits at step ST2 until the count up, and the compressor (11) is operated at the minimum capacity.

Subsequently, when the first timer (T1) counts up, the process proceeds to step ST3, where the capacity changing means (24) changes the capacity of the compressor (11) from the minimum capacity to the maximum capacity, and the second The timer (T2) is counted. Then, the process proceeds to step ST4 and the second timer (T
It is determined whether or not 2) has counted up, and the process waits at step ST4 until the second timer (T2) counts up.

After that, when the second timer (T2) counts up, for example, when 25 seconds elapse, the process proceeds to step ST5, where the pump down control means (23) fully opens the electric expansion valve (EV) and Open / close valve (WV)
While the valve is closed, the compressor (11) is stopped. As a result, only the refrigerant accumulated in the liquid reservoir (19) is stored in the evaporator (1
It will flow to 4).

Then, from step ST5 to step ST
6, the defrost control means (22) causes the compressor (1
1) is started to start defrost operation, the three-way solenoid valve (TV) is switched, and hot gas is bypassed from the compressor (11) using the refrigerant accumulated in the liquid reservoir (19). It will flow to the path (17) and will be fed to the evaporator (14) for defrosting.

Therefore, at the start of the pump down operation, the capacity of the compressor (11) is set to the minimum capacity, and then the capacity of the compressor (11) is changed to the maximum capacity. When 11) is switched from the low capacity steady operation state to the pump down operation, a large amount of high pressure refrigerant gas is not discharged from the compressor (11), so high pressure cut can be prevented. In particular, even when the outside air temperature is high, the high pressure cut can be prevented, so that a restart operation is not required and a smooth continuous operation can be performed.

Further, even when the refrigerant storage capacity of the receiver (13) in the liquid storage means (18) is small, high pressure cut can be prevented, so that the receiver (1)
The capacity of 3) can be reduced, and the overall size of the device can be reduced.

In the above embodiment, the capacity changing means (24) sets the capacity of the compressor (11) to the minimum capacity and the maximum capacity, but as shown in FIG. The capacity of the compressor (11) may be set to the capacity before the pump-down operation, and then changed to the maximum capacity.

Although the liquid reservoir (19) is provided on the high pressure liquid pipe side, it may be provided on the low pressure liquid pipe side.

The present invention is not limited to the refrigerant circulation circuit (1) of the embodiment, and is not limited to the one provided in the refrigerating container.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a refrigerant circuit diagram.

FIG. 3 is a control flow chart of pump down operation.

FIG. 4 is a characteristic diagram of a discharge refrigerant gas pressure of a compressor with respect to time, showing a conventional example.

[Explanation of symbols]

 1 Refrigerant Circulation Circuit 2 Controller 11 Compressor 12 Condenser 14 Evaporator 17 Hot Gas Bypass Path 18 Liquid Storage Means 21 Capacity Control Means 22 Defrost Control Means 23 Pump Down Control Means 24 Capacity Change Means EV Electric Expansion Valve (Expansion Mechanism)

Claims (2)

(57) [Claims] 1. A refrigerant circulation circuit (1) comprising: a variable capacity compressor (11), a condenser (12), an expansion mechanism (EV), and an evaporator (14), which are connected in order; A hot gas bypass passage (17) for supplying the hot gas discharged from the compressor (11) to the evaporator (14) by bypassing at least the condenser (12), and the hot gas bypass passage (17) bypassing the hot gas bypass passage (17). In a refrigerating device provided in a part of a refrigerant circulation circuit (1) and having a liquid storage means (18) for confining a refrigerant, a capacity control means for controlling the capacity of the compressor (11) according to a load. (21) and the refrigerant (1) when the evaporator (14) is frosted.
8), a pump down control means (23) for performing a pump down operation so as to be collected, and the pump down control means (2)
In the pump down operation of 3), the capacity of the compressor (11) is set to a low capacity at the start of operation, and a capacity changing means (24) for changing the capacity to a high capacity after a predetermined time, and a pump by the pump down control means (23). A defrost control means (22) for performing a defrost operation by flowing a hot gas from the compressor (11) to the hot gas bypass passage (17) by utilizing a part of the refrigerant of the liquid storage means (18) after the completion of the down operation.
An operation control device for a refrigeration system, comprising: 2. The operation control device for a refrigerating apparatus according to claim 1, wherein the capacity changing means (24) sets the capacity of the compressor (11) to the minimum capacity at the start of the pump down operation,
An operation control device for a refrigeration system, which is configured to change to a maximum capacity after a predetermined time.