JPS6237647A - Refrigerator - Google Patents

Abstract

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

Description

Detailed Description of the Invention (Industrial Utilization ¥1) The present invention relates to a refrigeration system, in particular, a hot gas bypass circuit that connects the outlet side of a compressor and the inlet side of an evaporator with a hot gas bypass circuit equipped with a hot gas valve. At the same time, a passing air temperature setting means for setting the temperature of the air passing through the evaporator, a passing air temperature detecting means for detecting the temperature of the air passing through the evaporator, and based on the outputs of these setting means and the detecting means. The present invention relates to a refrigeration system including a control means for controlling the opening degree of the hot gas valve to adjust the amount of hot gas bypass.

(Prior Art) A refrigeration system of this type applied to a container for refrigeration operation is known as described in Japanese Patent Application Laid-open No. 122863/1983.

This refrigeration system will be briefly explained based on FIG. 6. A gas pipe (52) connecting a compressor (50) and a condenser (51)
) is equipped with a gas valve (53) consisting of a three-force proportional valve, and the gas pipe (5) is connected via the hot gas valve (53).
2) and the liquid pipe (55) on the inlet side of the evaporator (54) with hot gas! <The hot gas valve (56) is connected to the hot gas valve (56), and the evaporator (54) is provided with a supply sensor (SS) that detects the temperature of the blown air.
3) the valve opening degree is controlled based on the temperature detected by the supply sensor (SS) to adjust the amount of hot gas bypassed through the pi and sp pipes (56), and
The outlet air temperature (TS) is adjusted.

Note that (EF) is a fan attached to the evaporator (54), and (M) is a motor of the fan (EF).

Further, the valve opening degree of the hot gas valve (53) is controlled by a proportional system based on the blown air temperature (TS). Furthermore, when this proportional control is used, a control delay occurs at the start of operation or when the load suddenly decreases, resulting in an overshoot in which the outlet air temperature (TS) drops extremely, and the Since stored cargo may suffer from freezing damage, the following measures are taken in the refrigeration equipment to prevent this. That is, the evaporator (54) is provided with a heater (not shown) so that the temperature (TS) of the air blown from the evaporator (54) is lower than a predetermined lower control temperature (TL) (see FIG. 5). When the temperature has decreased, the compressor (50) is stopped and the heater is energized, and the heat generated by the heater is used to raise the blown air temperature (TS).

(Problems to be Solved by the Invention) However, in such a case, in order to control the temperature of the blown air, firstly, a heater must be provided separately, which increases manufacturing costs. , Secondly, the frequency of starting and stopping of the compressor (50) increases,
There was a problem that the life of the compressor (50) was shortened.

Therefore, an object of the present invention is to reduce the valve opening degree of the hot gas valve when the temperature of the air passing through the evaporator (suction or blowout air temperature) falls below a predetermined control lower limit temperature. The control valve opening based on the passing air temperature is forcibly changed to a large opening, and the heat of the hot gas is effectively used to increase the passing air temperature of the evaporator, as in the conventional method. The object of the present invention is to suppress the overshoot of the passing air temperature in the same way as in the past without stopping the compressor or providing a heater.

(Means for solving m points between) The configuration of the present invention will be explained based on FIGS. 1 and 2.

The one shown in FIGS. 1 and 2 connects the outlet side of the compressor (1) and the inlet side of the evaporator (5) with a hot gas bypass circuit (A) equipped with a hot gas valve (7). passing air temperature setting means (SP) for setting the temperature of the air passing through the evaporator (5); passing air temperature detecting means (SS, RS) for detecting the temperature of the air passing through the evaporator (5); A control means (15) that controls the opening degree of the hot gas valve (7) to adjust the amount of hot gas bypass based on the outputs of the setting means (SP) and the detection means (SS, RS).
It is equipped with

Further, a control lower limit temperature setting means (16) for setting a lower control limit temperature lower than the set temperature of the passing air temperature setting means (88, RS), this control lower limit temperature setting means (16) and the detecting means (SS, determination means (17) inputting the output of the hot gas valve (RS) and determining whether the passing air temperature is equal to or lower than the control lower limit temperature; ) is provided with a changing means (18) for changing the opening degree of the valve to a set opening degree that is fully open or close to fully open.

In Fig. 2, (2) is the condenser, (3) is the temperature-sensitive expansion valve,
(EF) is a fan attached to the evaporator (5); (M)
is the fan motor.

(Function) When the determining means (17) determines and outputs that the temperature of the air passing through the evaporator (5) has become equal to or lower than the control lower limit temperature, the changing means (18) The valve opening degree of the valve (6) is forcibly changed to a large opening degree side with respect to the control valve opening degree based on the passing air temperature by the control means (15), and the Evaporator (5)
Since the amount of hot gas to be bypassed is increased, the heat of this hot gas can reduce the over-pursuit of the temperature of the air blown from the evaporator (5), that is, the amount of lowering the temperature to below the control lower limit temperature, and The over/neat time can also be shortened.

Moreover, since the compressor (1) is not particularly stopped,
The frequency of starting and stopping of the compressor (1) is reduced, and the durability of the compressor (1) is also improved.

(Example) The one shown in Fig. 2 is a container refrigeration system.This refrigeration system performs so-called refrigeration operation, which controls the inside of the refrigerator to a set temperature lower than a predetermined temperature, and a refrigerating operation that controls the interior of the refrigerator to a set temperature lower than the predetermined temperature. Two modes of refrigeration operation are possible: a so-called refrigeration operation in which the temperature is controlled.

To explain below, the refrigeration system includes a compressor (1), an air-cooled condenser (2), a water-cooled condenser (3), and a temperature automatic expansion valve (4).
) and the evaporator (5) are sequentially connected through refrigerant piping to form a refrigerant circuit.

A hot gas valve (7) consisting of a three-way proportional control valve is installed in the discharge gas pipe (6) connecting the compressor (1) and the air-cooled condenser (2). The hot gas bypass pipe (8) via the gas pipe (7)
6) and a liquid pipe (9) on the inlet side of the evaporator (5).

Thus, the hot gas valve (7) and the hot gas bypass pipe (8) form a hot gas bypass circuit (A).

In addition, in FIG. 2, (41) and (42) are a temperature sensing cylinder and a pressure equalizing pipe provided in the expansion valve (4), and the pressure equalizing pipe (42)
A three-way valve (43) is installed in the evaporator (5) to selectively equalize the pressure on the outlet side of the evaporator (5) and the pressure on the side of the hot gas bypass pipe (8) to the expansion valve (4). I am trying to make it work as a function.

Further, (D) is a drain pan heater provided below the evaporator (5), and the drain pan heater (D) has a defrost bypass branched from the hot gas bypass pipe (8) via a three-way valve (8a). A pipe (8b) is connected.

Note that (10) is a branch flow n provided in the artificial side liquid pipe (9) of the evaporator (5), and (11) is an accumulator.

Further, the evaporator 4 (5) is provided with a supply sensor (SS) that acts as a passing air temperature detection means that detects the temperature of the passing air, and a supply sensor (SS) that detects the temperature of the blown air, and a return sensor (RS) that detects the temperature of the suction air. has been established.

Note that this refrigeration system performs defrost operation by hot gas bypass, and in order to keep the amount of refrigerant circulated during this defrost operation at an optimal predetermined amount, a pair of first and second refrigerant are installed in the liquid pipe (9). 2 Solenoid on/off valves (13) (14
) is installed so that a predetermined amount of liquid refrigerant can be measured in the liquid pipe section (9a) between these on-off valves (13) and (14).

The operation of the refrigeration system described above is controlled by the control circuit shown in FIG.

This control circuit includes an input poem output section and a central processing section (C
Each electrically connected device is connected to a controller (C) comprising a microcomputer (PU) and a memory section (M), and a power supply section.

That is, ■ The 7ri source of the controller (C) has AC 24V.
The power source (Y) is connected via the operation switch (3-88).

■ The input section of the controller (C) is equipped with the supply sensor (which detects the outlet air temperature (TS) during refrigeration operation).
SS), the return sensor (RS) that mainly detects the intake air temperature (TR) during refrigeration operation, the temperature sensor (Thl) that detects the end of defrost operation, and the passing air temperature setting means of the evaporator (5). As a result, a setting means (SP) for setting the blowing air temperature is connected.

■ The output section of the controller (C) has the first output contact (
Xl), the high pressure switch (63H), the low pressure switch (63L), and the start/stop switch (8) of the compressor (1).
8C) and the parallel circuit of the condenser fan (CF) are connected, and the evaporator fan (E F) start/stop switch 25 (88EF) is connected to the second output contact (X2). 3 output contacts (X
3) is the solenoid (20R) of the first electromagnetic on-off valve (13).
1) is connected, the fourth output contact (X4) is connected to the solenoid (2OR2) of the second electromagnetic on-off valve (14), and the fifth output contact (X5) is connected to the pressure equalization pipe switch of the expansion valve (4). The solenoid (20RS) of the 3-way valve (43) for switching the drain pan heater (D) is connected to the 6th output contact (X6), and the solenoid (20R4) of the 3-way valve (8a) for switching the drain pan heater (D) is connected to the 6th output contact (X6). Furthermore, a drive unit (20 MV) for a hot gas valve (7) is connected.

The refrigerating operation or freezing operation described above is performed depending on the level of the set temperature (TO) of the setting means (SP).

Further, the microcomputer of the controller (C) includes the supply sensor (SS) 11 during refrigeration operation;
A control means (15) for PID controlling the valve opening degree of the hot gas valve (7) based on the output from the setting means (SP); and a set temperature of the setting means (SP) during refrigeration operation. (T
Control lower limit temperature (TL
) for setting the control lower limit temperature setting means (step 6), these setting means (16) and the supply sensor (SS
) for determining whether the blown air temperature (TS) is equal to or lower than the control lower limit temperature (TL); A changing means (18) for changing the opening degree of the hot gas valve (6) to full open is provided.

In the refrigeration system mentioned above, the aim is to control the outlet air temperature (TS) within a range of ±2'C with respect to the set temperature (TO). TS) is within the following predetermined temperature range with respect to the set temperature (To), the control means (15)
The opening degree of the hot gas valve (7) is controlled by PID.

That is, when the blowing air temperature (TS) rises, -1.5℃<
TS-To<2.5℃ Also, when the blowing air temperature (TS) decreases, -1.5℃
<TS-To≦1.0°C, the control means (15) controls the PID
I try to control it.

Moreover, the said changing means (18) is the hot gas valve (7).
Forcibly open II! I'm trying to set it to 2100%.

Further, the evaporator fan (EF) can be operated at high speed or at low speed.

Next, a case in which a refrigeration operation is performed in the refrigeration apparatus in which the set temperature (TO) set by the setting means (SP) is set to a temperature lower than the predetermined temperature will be described based on the flowchart of FIG. 4.

When the operation switch (3-88) is closed, the supply sensor (SS) is selected and the supply sensor (SS) is selected.
The blowing air temperature (TS) is read from SS) (step 100).

Although not shown, the first and second Ti magnetic on-off valves (13) and (14) are connected to each solenoid (20R1) (2OR
2) is energized and opened.

Furthermore, the set temperature (TO) and the blowing air temperature (TS)
After the temperature difference (TS-To) between the two is calculated, a determination is made (step 101). In this temperature difference determination, (1) If the blowing air temperature (TS) is above the PID control temperature range (TS-To≧2°5°C), the blowing air temperature (TS) is It is determined whether the temperature is higher than 15°C (Step 102), and if it is higher than IE';°C, the compressor (1) is operated (Step 103).
At the same time, the evaporator fan (EF) is driven at low speed (step 104), and the process returns to step 102. On the other hand, if the blowing air temperature (TS) is 15°C or less, the compressor ( 1) (step 105), and the evaporator fan (EF) is rotated at high speed (step 106).

Note that the rotational speed of the fan (EF) is determined by the blowing air temperature (T
The purpose of changing the height by S) is to prevent overload operation.

In this case, although not shown, the pressure equalizing pipe (
The three-way valve (43) interposed in the expansion valve (42) is operated to introduce a suction gas pipe (12) (1 m pressure) into the expansion valve (4), and the expansion valve (4) is At the same time as the degree control, the opening degree of the hot gas valve (7) is adjusted to 0%.

■ Also, in step 101, the blowing air temperature (T
If S) is within the control temperature range, the system will shift to PID control as described below, and if the blown air temperature (TS) is below the PID control temperature range (TS-TO≦1.5°C) That is, if the blowing air temperature (TS) is too low, the compressor (1) is operated (step 107), and
The evaporator fan (EF) is operated at high speed, and the operation is shifted to full hot gas bypass operation (described later) (108).

Below, we will first explain the case (2) above. The process proceeds from step 101 to step 102, and the outlet air temperature (TS
) is determined to be 15° C. or lower, the compressor (1) and the evaporator fan (EF) are driven as described above,
The refrigerant discharged from the compressor (1) is
) → Air-cooled condenser (2) → Water-cooled condenser (3) → Expansion valve (4
) → evaporator (5) → compressor (1).

Then, the blowing air temperature (TS) is determined again (step 109), and if the blowing air temperature (TS) is less than 5°C, the blowing air temperature (TS) and the set temperature (TO) are further determined. (step 110), and based on this comparison result,
Control of the opening degree of the hot gas valve (7) is selected from among three options as described later. On the other hand, (1) If the blowing air temperature (TS) is 5° C. or higher, the pull-down operation is controlled based on the suction air temperature (TR) as described later in order to perform the pull-down operation at the start of operation.

However, to explain the above case (■) below, step 1
As a result of the determination in step 10, if (TS-40) is out of the PID control range and is greater than 1°C, this pull-down operation is continued and the blowing air temperature (TS) is determined again in step 110. In addition, if the blowing air temperature (TS) falls below the PID control temperature range and is below -1.5°C in step 110, the hot gas valve (7) is forcibly fully opened (1
00% opening) (step 111), and the compressor (
The entire amount of hot gas discharged from 1) is transferred to the evaporator (5).
), and the hot gas is operated by bypassing the total amount of hot gas to increase the temperature of the blown air using the heat value of the hot gas. That is, the total amount of hot gas discharged from the compressor (1) is transferred from the compressor (1) → hot gas valve (7) → hot gas bypass pipe (8) → evaporator (5) →
It is circulated through the compressor (1). At this time, the three-way valve (8a) installed in the hot gas bypass pipe (8)
is switched to block the flow of hot gas to the defrost bypass pipe (8b).

Then, the temperature difference (TS-To) is further determined (step 112), and if this temperature difference is = 6°C<TS-To<-1.5°C, operation is continued with this hot gas full bypass. , and when TS-To<-8°C, the compressor (1) is stopped; on the other hand, when -1.5°C<TS-T.

If the temperature difference (TS
-To) is determined.

On the other hand, in step 110, the blowing air temperature (T
S) is within the control temperature range, the hot gas valve (7) is opened to the bypass pipe (8), and the opening degree of the hot gas valve (7) is within the control temperature range ( T.S.
) and the set temperature (TO) (step 113).

At this time, the three-way valve (43) interposed in the pressure equalization pipe (42) causes the hot gas bypass pipe (8) side pressure to act on the expansion valve (4) as equalization pressure. As a result, the amount of liquid refrigerant passing through the expansion valve (4) is actively suppressed.

Also during this PID control, the temperature difference (TS-To) is sequentially determined (step 114), and if the temperature difference (TS-To) is within the PID control temperature range, the PID
While the control continues, the temperature difference (TS-TO) is -1
, 5°C (lower control limit temperature If (TL)), the process proceeds to step 111, where the hot gas valve (7) is forcibly fully opened and operation is performed with full gas bypass. Furthermore, the temperature difference (TS-T
o) becomes larger than 2.5°C (control upper limit temperature), the opening degree of the hot gas valve (7) is set to 0% (step 11).
5) Return to step 110 and check the blowout air temperature (TS)
Based on this determination result, operation is continued according to the flow described above.

On the other hand, in the case of (2) and (2), which are not explained in step 101, if the temperature difference (TS-TO) is within the PID control temperature range in step 101, the process proceeds to step 105, and the PID control temperature during the descent is again It is determined whether or not the range is within the range, and operation control is proceeded in the same manner as described above.

In addition, if the temperature difference (TS-To) is -1.5°C or less (control lower limit temperature (TL)), directly step 11
In step 1, the hot gas valve (7) is forcibly opened completely to bypass the entire amount of hot gas.

As described above, the blowing air temperature (TS) is the control lower limit temperature (
TL) or below, even at the beginning of operation, P
Even when ID control is being performed, the hot gas bypass valve (7) is immediately forced to fully open, and the compressor (1) is
) to the evaporator (5), the air blown from the evaporator (5) is heated by the heat of the hot gas and the heat generated by the fan motor (M), and rapidly The temperature rises.

As a result, the overshoot temperature range (Δt
), it is possible to effectively prevent the blowing air temperature (TS) from dropping below the control target (TO-2°C), and the open neat time can also be shortened.

Moreover, since the compressor (1) is not stopped, the frequency of starting and stopping is reduced, and the durability of the compressor (1) is also improved.

Furthermore, the time required from the pull-down operation to stabilization of the control can also be shortened.

Next, in step 109, the blowing air temperature (TS)
A case where it is determined that the temperature is 5° C. or higher will be briefly explained.

In the following steps, at the beginning of operation, the heat load due to the heat of the internal walls of the container is usually large, and this heat load is higher than the outlet air temperature (TS).
Considering that the temperature is reflected better by R), at the beginning of operation, operation control was performed based on this intake air temperature (TR), and the control was quickly shifted to stable control (PID control) at the start of operation. It is determined whether or not this is the first time (first time) (step 116), and if it is the -th time, the return sensor (R
S) is selected and the operation is controlled based on the intake air temperature (TR).

Then, the suction air temperature (TR) and the set temperature (To)
The temperature difference (TR-To) between
temperature difference (e.g. 2
℃), the hot gas valve (10
), that is, full cooling operation is performed at 0% opening.

Moreover, if the temperature difference (TR-To) becomes smaller than 2°C, it can be detected that the temperature of the internal wall surface of the refrigerator has been cooled to near the set temperature (TO).
At the same time, the return sensor (RS) is switched back to the supply sensor (SS), and the operation is controlled based on the blown air temperature (TS) (step 119).

Therefore, in step 119, (TS-TO) is 1
℃ or higher, the compressor (1) is restarted (step 120), the process proceeds to step 113, and the control means (1) is restarted (step 120).
PID the valve opening degree of the hot gas valve (7) using 15).
It's about controlling.

In addition, in the flowchart shown in FIG. 4, the temperature difference (
The compressor (1) is stopped when the temperature difference (T S -To)
is set to 2°C, the blowing air temperature (TS) corresponding to this temperature difference is -1.5 which is the 0 control lower limit temperature (TL).
℃, and if the lower limit temperature (TL) is not exceeded, the compressor (1) is operated as described above.
There is no need to stop the hot gas valve (7) (it is also possible to shift to the opening degree control of the hot gas valve (7), which will be explained next).

On the other hand, in step 117, the temperature difference (TR-To) between the suction air temperature (TR) and the set temperature (To) is 2°C.
If this is the case, full operation will continue.

Next, to briefly explain the case where the set temperature of the temperature setting device (SP) is set to the set temperature or lower and refrigeration operation is performed, by closing the operation switch (3-88), the first and second The electromagnetic on-off valves (13) and (14) are opened by the excitation of each solenoid (20R1) (2OR2), and operation is started.

The compressor (1) is controlled on and off by the temperature sensor (RS) on the suction side, and the expansion valve (4) is controlled on and off.
), the three-way valve (43) is switched so as to guide the pressure on the outlet side of the evaporator (5) to the expansion valve (4), and the hot gas bypass pipe (42) is connected to the hot gas bypass pipe. The three-way valve (8a) installed in the bypass pipe (8) allows the hot gas flowing through the bypass pipe (8) to be connected to the drain pan heater (
D) can be switched to bypass.

In the above embodiment, the opening degree of the hot gas valve (7) was controlled based on the blowing air temperature (TS).
The determination may be made based on the intake air temperature (TR).

In addition, the hot gas valve (
The opening degree set in 6) does not have to be 100%, and the PI
The valve opening may be changed to a larger opening than the valve opening under the D control.

(Effects of the Invention) As described above, according to the present invention, when the temperature of the air passing through the evaporator overshoots the lower limit control temperature, the valve opening degree of the hot gas valve is adjusted to +]ij. Since the control valve opening is changed to a large opening based on the passing air temperature, a large amount of hot gas is supplied to the evaporator, eliminating the need for a separate heater as in the past. , 11Ti The above-mentioned overshoot can be suppressed without stopping the compressor.

Therefore, it is not necessary to provide a heater as in the prior art, and the installation cost can be lowered, and the durability of the compressor can also be improved.

[Brief explanation of drawings]

Figure 1 is a diagram corresponding to claims of the present invention, Figures 2 to 5 are detailed explanatory diagrams of the present invention, Figure 2 is a refrigerant circuit diagram, Figure 3 is a control circuit diagram, and Figure 4 explains operation. Flowchart, 5th
The figure is an explanatory diagram illustrating changes in the temperature of the blown air during operation, and FIG. 6 is a refrigerant circuit diagram of a conventional example. (1)...Compressor (4)...Evaporator (6)...Hot gas valve (8)...Hot gas bypass pipe (15)...
... Control means (16) ... Control lower limit temperature setting means (17) ...
...Judging means (18) ... Changing means (A) ... Hot gas bypass circuit (SS) ...
... Supply sensor (passing air temperature detection means) (SP) ... Setting means (passing air temperature setting means)

Claims (1)

[Claims] (1) The outlet side of the compressor (1) and the inlet side of the evaporator (5) are connected by a hot gas bypass circuit (A) equipped with a hot gas valve (7), and the evaporator (5) is A passing air temperature setting means (SP) for setting the temperature of the air passing through, a passing air temperature detecting means (SS, RS) for detecting the temperature of the air passing through the evaporator (5), and these setting means (
A refrigeration system comprising: a control means (15) for controlling the opening degree of the hot gas valve (7) to adjust the amount of hot gas bypass based on the outputs of the detection means (SS, RS) , a control lower limit temperature setting means (16) for setting a lower control limit temperature lower than the set temperature of the passing air temperature setting means (SP), this control lower limit temperature setting means (16) and the detecting means (SS, RS); determination means (17) inputting the output of the above and determining that the passing air temperature is below the control lower limit temperature; The valve opening degree is controlled by the control means (
15) A refrigeration system characterized by being provided with a changing means (18) for changing the control valve opening to a larger opening.