JPH0535333B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a refrigeration system, and more particularly, a hot gas valve, a hot gas valve, a condenser, and an expansion mechanism to bypass hot gas to an evaporator to control capacity. The present invention relates to a refrigeration system equipped with a gas bypass path.

(Prior Art) Conventionally, the hot gas discharged from the compressor bypasses the condenser and expansion mechanism to the evaporator to control the temperature of the blown air, as disclosed in, for example, Japanese Patent Laid-Open No. 59-122863. It is known as shown in the publication No.

This conventional example, as schematically shown in FIG.
A hot gas bypass path H is connected to the high pressure gas pipe B connecting the discharge side of the compressor A and the inlet side of the condenser C, bypassing the condenser C and the expansion valve EV and connecting it to the inlet side of the evaporator E. A hot gas valve HV is connected to the hot gas bypass path H, and the evaporator E is provided with a supply sensor SS for detecting the temperature of the air blown out from the evaporator E.
Further, a controller CR is provided which inputs the temperature of the blowing air detected by the supply sensor SS and outputs an opening/closing signal to the hot gas valve HV based on a comparison between this blowing air temperature and a set temperature of the blowing air, and controls the hot gas valve HV. By controlling the opening to a predetermined degree, the temperature of the air blown from the evaporator E is controlled.

(Problems to be Solved by the Invention) As described above, the hot gas valve HV is determined based on the blowing air temperature detected by the supply sensor SS.
When controlling with the controller CR by comparing with the set temperature, the blowing air temperature is compared with the controller CR.
When the upper limit of the control temperature range is reached for the set temperature set in Immediately after starting, the temperature of the blown air rises and exceeds the upper limit, and the operation is switched to full cooling again, and this state is repeated and stabilized thereafter.

For this reason, there was a problem in that it took a long time to stabilize the control during pull-down.

In addition, during pull-down when this problem occurs, in addition to the first pull-down after turning on the power and starting operation, when changing the set temperature and checking the operation by changing the set temperature, the blowing air temperature changes to the set temperature. For example, when the temperature of the blown air is 5°C or more relative to the set temperature, for example, when the temperature of the blown air is 5°C or more relative to the set temperature even after 30 minutes have passed after the defrost operation is completed, and when the temperature of the blown air is 5°C or more relative to the set temperature for 30 minutes or more. This includes the pulldown time when .

An object of the present invention is to shorten the time required to stabilize the control during pulldown even when the heat capacity is large.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention sets the hot gas valve control based on the blowout air temperature, which is affected by the internal heat capacity, at the time of pull-down, so that the suction air temperature is the same as the blowout air temperature. The temperature is stopped until the temperature reaches the stable operation temperature, and the internal heat capacity is small, that is, the container wall, etc. is cooled to near the set temperature, which is read by detecting the suction air temperature, and then the normal operation is determined by the outlet air temperature. As shown in FIGS. 1 to 3, the hot gas is bypassed to the evaporator 4 by bypassing the hot gas valve 10, the condensers 2 and 3, and the expansion mechanism 5. a hot gas bypass passage 8, the hot gas valve 1
The refrigeration system is such that the temperature of the air blown from the evaporator 4 is controlled by opening and closing the evaporator 4.
Supply sensor SS that detects the temperature of the outlet air
, a return sensor RS that detects the temperature of the intake air of the evaporator 4, and an air temperature setting device 21, and also includes a temperature set by the setting device 21, a blowing air temperature detected by the supply sensor SS, and the return sensor RS. The comparison means 22 compares the temperature of the intake air detected by the sensor RS with the set temperature and the temperature of the discharged air.
An output means 23 outputs an opening/closing signal to 0, and a comparison between the blown air temperature and the set temperature by the comparison means 22 during pull-down is performed by the return sensor RS.
When the switching means 25 switches to the comparison between the intake air temperature detected by and the set temperature, and the comparison by the comparison means 22 is switched to the intake air temperature and the set temperature,
The output of the opening/closing signal from the output means 23 to the hot gas valve 10 is stopped, and pull-down operation is performed based on the comparison result between the intake air temperature and the set temperature by the comparison means 22, so that the intake air temperature reaches the set temperature. On the other hand, the controller 20 is provided with a pull-down operation control means 24 for stopping the pull-down operation when the temperature difference reaches a temperature difference for stable operation.

(Function) During pulldown, the opening/closing control of the hot gas valve 10 is stopped even if the blowing air temperature falls within the control range of the set temperature until the blowing air temperature reaches the temperature difference between the set temperature and the temperature during stable operation. The hot gas valve 10 does not bypass the hot gas until the heat capacity inside the refrigerator becomes small. In other words, it detects that the heat capacity becomes small due to the suction air temperature, and the suction air temperature reaches the set temperature to ensure stable operation. When a temperature difference is reached, the pull-down operation is stopped and control is then performed based on the temperature of the blown air, which shortens the time it takes to stabilize control during pull-down.

(Example) What is shown in Fig. 3 shows the refrigerant piping system of a container refrigeration system.
This is no different from the conventional example shown in the figure.

That is, in FIG. 3, 1 is a compressor, 2 is an air-cooled condenser, 3 is a water-cooled condenser, 4 is an evaporator, 5 is a temperature-sensitive expansion valve having a temperature-sensing section 5a, and 6 is an accumulator. Each device is connected by a refrigerant pipe 7, and forms a refrigeration cycle in which the evaporator 4 cools the air inside the refrigerator, and also connects the discharge side of the compressor 1 with the inlet side of the air-cooled condenser 2. The pipe 71 is connected to the condenser 2,
3 and the temperature-sensitive expansion valve 5 are connected to a hot gas bypass passage 8 leading to the evaporator 4, and its outlet side is connected to a low-pressure liquid pipe 7 between the expansion valve 5 and the evaporator 4.
2, and this hot gas bypass path 8
A hot gas valve 10 is interposed at the connection point to the high pressure gas pipe 71.

In the embodiment shown in FIG. 3, a solenoid valve SV ₁ is provided in the high-pressure liquid pipe 73 between the condenser 3 and the expansion valve 5 to enable pump-down operation until an instruction to start the defrost operation is provided. On the upstream side of this solenoid valve SV ₁ , that is, on the condenser 3 side, solenoid valves SV ₂ are installed at regular intervals, and in the liquid pipe section between these solenoid valves SV ₁ and SV ₂ , pump down operation is performed. A certain amount of refrigerant is measured out of the refrigerant to be confined by the solenoid valve _SV2 , and the solenoid valve is closed.
By opening SV ₁ , a certain amount of refrigerant is configured to flow into a defrost circuit that performs defrost operation, that is, a defrost circuit consisting of a compressor 1, a hot gas valve 10, a hot gas bypass passage 8, an evaporator 4, and an accumulator 7. are doing.

In addition, in the one shown in FIG. 3, a drain pan heater 11 is attached to the evaporator 4, and a three-way solenoid valve is installed in the hot gas bypass path 8.
An SV ₃ is interposed so that it is possible to select whether the hot gas is guided to the evaporator 4 via the drain pan heater 11 or directly.

Further, the pressure equalizing pipe 5b of the expansion valve 5 is connected to the low pressure gas pipe 74, and a part of the pressure equalizing pipe 5b is connected to the hot gas bypass path 8,
A control passage 12 is provided for guiding a portion of the hot gas to the pressure equalizing pipe 5b and forcibly reducing the opening degree of the expansion valve 5 by the pressure of this hot gas. A pressure equalizing pipe 5b is connected to the connection site, and the hot gas bypass path 8 is connected to the pressure equalizing pipe 5b.
and the low-pressure gas pipe 74, and a three-way solenoid valve SV ₄ is provided that selectively communicates with one of the two and cuts off communication with the other.

In addition, in FIG. 3, 13 is a dryer, 14 is a liquid indicator, 15 is a manual shutoff valve, and 16 is a dryer.
17 is an indoor fan attached to the evaporator 4, and 17 is an outdoor fan attached to the air-cooled condenser 2.

Further, the hot gas valve 10 is mainly an electric three-way valve, and can control the valve opening degree to the hot gas bypass path 8 from 0 to 100% in proportion to the voltage,
A proportional control valve is used to adjust the capacity by controlling the hot gas bypass amount to the evaporator 4, and at the same time, the opening degree is 100% during defrost operation.
The electric part 20M of the hot gas valve 10 performs PID control of its valve opening degree by a controller 20, which will be described later.

Therefore, in the above configuration, the evaporator 4
A supply sensor SS for detecting the temperature of the blown air is provided on the outlet side of the blown air, and a return sensor RS is provided on the inlet side for detecting the temperature of the suction air, and a setting device 21 for setting the air temperature; A controller 2 that compares the blowout air temperature (ST) detected by the supply sensor SS with a set temperature (SP) of the blowout air, and outputs an opening/closing signal to the hot gas valve 10 based on the comparison result.
0 is used to control the operation of the refrigeration system described above.

The operation control circuit using the controller 20 is as shown in FIG. It is equipped with a central processing circuit CPU and a memory circuit M that constitute a comparison means 22, an output means 23, and a pull-down operation control means 24, and the input side I is connected to the supply sensor SS and return sensor RS, A defrost timer 2D and a temperature sensor TH for detecting the completion of defrosting are connected, and the hot gas valve 10 is connected to the output side O.
Connecting the electric part 20M and the solenoid relays 20R ₁ to 20R ₄ of the solenoid valves SV ₁ to _{SV 4} ,
A compressor motor start/stop control circuit in which a high voltage switch 63H, a low voltage switch 63L, an overcurrent relay 51c, a protection relay 49c of the compressor 1 and an electromagnetic switch 88c of the compressor motor are connected in series, and an indoor fan 16 and an outdoor fan 17 each motor 88EF, 8
8 CFs are connected to each other.

Therefore, in the above configuration, when performing refrigeration operation, the temperature of the air cooled in the evaporator 4 is adjusted based on the set temperature (SP) of the air set by the setting device 21. The temperature difference (ST-
SP), the opening degree of the hot gas valve 10 is set to 0.
~100%, and bypass hot gas according to this opening degree, and when pulling down,
In other words, at the first pull-down after turning on the power and starting operation, or during the pre-use survey (Pre Trip
When changing the set temperature (SP) and checking the operation during inspection), when the blowing air temperature (ST) is, for example, 5°C or more relative to the set temperature (SP), and when the defrost If the blowing air temperature (ST) is 5°C or higher relative to the set temperature (SP) even after 30 minutes have passed after the end of operation, or if the blowing air temperature (ST) is 5°C or higher relative to the set temperature (SP) for 30 minutes or more, When pulling down when the temperature is above ℃, the supply sensor
Switch from SS to return sensor RS, and adjust the discharge air temperature (ST) and set temperature (SP) until the intake air temperature RT reaches the temperature difference (RT - SP) during stable operation from the set temperature (SP). stopping the opening control of the hot gas valve 10 based on the temperature difference;
This is done so that the pull-down operation with full cooling operation continues.

When the suction air temperature RT becomes the temperature difference (RT-SP) with respect to the set temperature (SP), the internal wall surface of the refrigerator is cooled to near the set temperature (SP),
This is the temperature difference when the internal heat capacity decreases, and is normally set to +2°C as shown in the control pattern shown in FIG.

Further, when the temperature difference is 2°C, the blowing air temperature (ST) changes depending on the capacity of the evaporator 4, but if the capacity is large, the set temperature (SP) is controlled as shown in Fig. 5. It is lower than the lower limit of the range. Therefore, the suction air temperature RT
When the difference in temperature from the set temperature (SP) becomes as described above, the pull-down operation is stopped. In this case, the operation of the compressor 1 is stopped to cancel the pull-down operation, but the capacity of the evaporator 4 is small, and the temperature difference between the suction air temperature RT and the set temperature (SP) is 2°C. When , the blowing air temperature (ST)
is within the control range for the set temperature (SP), it is sufficient to shift to the opening control of the hot gas valve 10 based on the blown air temperature (ST) without stopping the compressor 1, or In this case, even if the blown air temperature (ST) is at the lower limit of the control range of the set temperature, the opening degree of the hot gas valve 10 can be increased to 100% without stopping the operation of the compressor 1.
It may be controlled to %.

Further, the opening degree control of the hot gas valve 10 based on the blowout air temperature (ST) is performed based on the temperature difference between the blowout air temperature (ST) and the set temperature (SP), and this temperature difference is the lower limit of the control range. (e.g. -1.5°C), the hot gas valve 10
The opening degree is 100%, and if the temperature difference increases further than the lower limit (for example, -6°C)
The compressor 1 is then stopped.

Further, in the above explanation, the control range for controlling the opening of the hot gas valve 10 is different between when controlling in the descending direction and when controlling in the ascending direction, and usually the control range in the descending direction is +1 ℃≧ST−
SP > -1.5℃, control range in the rising direction is -1.5℃
≦ST−SP＜2.5℃.

Next, the refrigeration operation of the refrigeration system constructed as above will be explained according to the flowchart shown in FIG. 4.

First, the set temperature is set to -3°C or higher, for example 0°C, using the setting device 21, and the blowing air temperature (ST) detected by the supply sensor SS and the set temperature (SP) are centrally calculated by the controller 20. Comparison calculations are performed in the processing circuit CPU.

When the temperature difference (ST-SP) between the set temperature (SP) and the blowing air temperature (ST) exceeds the maximum value of the control range, that is, 2.5°C, the compressor 1 is driven and , outlet air temperature (ST)
For example, when the temperature is higher than 15°C, the indoor fan 16 is driven at a low speed, and when the temperature is below 15°C, the indoor fan 16 is driven at a high speed. The speed control of these indoor fans 16 is to prevent overload operation.

The blown air temperature (ST) decreases as the compressor 1 is driven, but if the blown air temperature (ST) is 5°C or more higher than the set temperature (SP), the operation is started by turning on the power. It is determined whether or not it is the first pulldown after the start, and if it is determined that it is the first pulldown, the supply sensor SS is switched to the return sensor RS based on this judgment, and the intake air detected by the return sensor RS is The temperature RT and the set temperature (SP) are compared and calculated by the central processing circuit CPU of the controller 20. Then, the temperature difference (RT−SP) between the suction air temperature RT and the set temperature (SP)
However, when the temperature difference that is considered to have cooled the internal wall surface to near the set temperature (SP) is, for example, 2°C or more, even if the blowing air temperature (ST) falls within the control range in the downward direction described above, Full cooling operation is performed without controlling the opening degree of the hot gas valve 10, that is, at 0% opening degree.

Furthermore, if the temperature difference (RT-SP) is lower than 2℃, it can be detected that the refrigerator has been cooled to near the set temperature (SP) even if the heat capacity of the internal wall surface is large. If it becomes lower, the return sensor RS to the supply sensor SS
Then, the operation is controlled based on the discharge air temperature (ST).

In addition, in the flowchart shown in FIG. 4, when the temperature difference (RT-SP) becomes lower than 2°C,
Although the compressor 1 is stopped, as mentioned above,
The opening degree of the hot gas valve 10 may be controlled to 100%.

Furthermore, the compressor 1 is stopped in relation to the capacity of the evaporator 4, and the temperature difference (RT-SP)
is set to 2℃, the outlet air temperature (ST) corresponding to this temperature difference is the lower limit of the control range -
This is done when the temperature has decreased by more than 1.5°C, and if the temperature has not decreased by more than the lower limit, there is no need to stop the compressor 1 as described above, and the hot gas valve 10, which will be explained later, is You may shift to opening degree control flow I.

Furthermore, if the compressor 1 is stopped, the blown air temperature (ST) increases, and the temperature difference (ST-SP) between the blown air temperature (ST) and the set temperature (SP) becomes, for example, 1°C or more. , the operation of the compressor 1 is started, and the process moves to the opening degree control flow I of the hot gas valve 10, which will be explained next.

In addition, when controlling the opening degree of the hot gas valve 10 to 100% instead of stopping the compressor 1, if the temperature difference (ST-SP) becomes 1°C or more, the hot gas is turned off at this stage. The flow then shifts to the opening degree control flow I for the valve 10.

In addition, even if the blowout air temperature (ST) is 5°C or higher than the set temperature (SP) and it is not the first pulldown, the blowout air temperature (ST )
is 5°C or more relative to the set temperature (SP), and when the pull-down operation is not performed due to this switching, the blowing air temperature (ST) remains relative to the set temperature (SP) even after 30 minutes have passed after the end of defrost operation. 5℃
In the above cases, and in normal operation (not defrost operation), if the blowing air temperature (ST) is 5°C or more compared to the set temperature (SP) even after 30 minutes have passed after the start of operation, the supply sensor SS The intake air temperature RT detected by the return sensor RS and the set temperature (SP) are compared and calculated in the central processing circuit CPU, and the intake air temperature RT and the set temperature are compared and calculated by the central processing circuit CPU. Until the temperature difference (RT-SP) from (SP) becomes, for example, 2°C,
Full cooling operation is performed with the opening degree of the hot gas valve 10 set to 0%.

On the other hand, when the blowing air temperature (ST) is lower than 5°C, in other words, when it is not during pull-down, that is, when it is not during the pull-down of each of the above-mentioned aspects such as during the first pull-down, the return sensor RS is activated as described above. The hot gas valve 10 is controlled based on the blowing air temperature (ST) detected by the supply sensor SS without being switched, and the control range during descent is -1.5°C.
<ST-SP≦1°C, a predetermined voltage is applied to the motorized part 20M of the hot gas valve 10, and the valve opening is controlled to be proportional to this voltage, and the hot gas discharged from the compressor 1 is is guided to the evaporator 4 at a flow rate corresponding to the opening degree of the hot gas valve 10, and the temperature of the blown air is controlled.

Then, when the temperature difference (ST-SP) becomes less than the lower limit of -1.5°C by controlling the opening degree of the hot gas valve 10, the opening degree of the hot gas valve 10 is changed to 100°C.
%, and even if the opening degree of the hot gas valve 10 is controlled to 100%, the temperature of the blown air continues to fall, for example, if it drops to more than -6°C, the compressor 1 is stopped. It is. By controlling the opening degree of the hot gas valve 10 to 100%, the temperature difference (ST-SP) can be reduced to the lower limit of -1.5°C.
When the absolute value becomes smaller and falls within the control range, the opening degree of the hot gas valve 10 is controlled.

In addition, the temperature difference (ST-
When SP) exceeds the upper limit of 2.5°C, the opening degree of the hot gas valve 10 is controlled to 0%, and full cooling operation is performed.

As described above, the blowing air temperature (ST) is adjusted to the set temperature (SP) by controlling the opening degree of the hot gas valve 10. However, during the pull-down described above, the opening degree control of the hot gas valve 10 is adjusted to the blowing air temperature (ST). ) to the suction air temperature RT. In other words, due to the temperature difference between the suction air temperature RT and the set temperature (SP), the internal wall surface of the refrigerator is cooled to near the set temperature (SP). The hot gas valve 10 detects that the internal heat capacity is decreasing, and the hot gas valve 10 is controlled by the outlet air temperature (ST), which is affected by the internal heat capacity until this detection.
By discontinuing the opening control, the time required for the outlet air temperature (ST) to stabilize with the set temperature (SP) during pull-down can be shortened.

In the embodiment described above, the temperature difference (RT-) between the suction air temperature RT and the set temperature (SP) is
SP) was set to 2℃, but this is an example when the outside temperature is 38℃ and the set temperature (SP) is 0℃.This temperature difference (RT-SP) is the set temperature at the first pulldown. The temperature difference between (SP) and stable operation may be used.

(Effect of the invention) The present invention provides a hot gas valve 10 and a condenser 2, 3.
and a hot gas bypass path 8 that bypasses the expansion mechanism 5 to bypass the hot gas to the evaporator 4, and the refrigeration system is such that the temperature of the air blown from the evaporator 4 is controlled by opening and closing the hot gas valve 10. It is equipped with a supply sensor SS for detecting the temperature of the air blown out from the evaporator 4, a return sensor RS for detecting the temperature of the intake air of the evaporator 4, and an air temperature setting device 21. Set temperature and said supply sensor
Comparison means 22 for comparing the blowing air temperature detected by the SS with the suction air temperature detected by the return sensor RS; and an output means 23 for outputting an opening/closing signal to the hot gas valve 10 based on the comparison result between the set temperature and the blowing air temperature. When pulling down, the comparison means 22 compares the blown air temperature and the set temperature,
A switching means 25 for switching to a comparison between the intake air temperature detected by the return sensor RS and a set temperature.
When the comparing means 22 switches the comparison between the suction air temperature and the set temperature, the output means 23 stops outputting the opening/closing signal to the hot gas valve 10, and the comparing means 22 changes the suction air temperature and the set temperature. The controller 20 includes a pull-down operation control means 24 that performs the pull-down operation based on the comparison result with the temperature and stops the pull-down operation when the intake air temperature reaches a temperature difference for stable operation with respect to the set temperature. Therefore, even if the heat capacity inside the refrigerator is large, such as during the first pulldown, it detects that this heat capacity has become small and starts pulldown operation when the suction air temperature reaches a temperature difference between the set temperature and stable operation. After stopping the hot gas valve 10, the temperature of the blown air can be adjusted by controlling the opening of the hot gas valve 10, and as a result, the time required to stabilize the temperature at the set temperature can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a block diagram explaining the principle of the present invention.
Fig. 2 is a schematic electrical circuit diagram, Fig. 3 is a refrigerant piping system diagram of a refrigeration system showing one embodiment of the present invention, Fig. 4 is a flowchart, Fig. 5 is an explanatory diagram of a control pattern, and Fig. 6 1 is a schematic refrigerant piping system diagram showing a conventional example. 2, 3... Condenser, 4... Evaporator, 5... Expansion mechanism, 8... Hot gas bypass path, 10... Hot gas valve, 20... Controller, 21... Setting device, 22... Comparison means , 23... Output means, 2
4...Pull-down operation control means, SS...Supply sensor, RS...Return sensor, 25...
...Switching means.

Claims (1)

[Claims] 1 includes a hot gas valve 10 and a hot gas bypass passage 8 that bypasses the condensers 2, 3 and the expansion mechanism 5 to bypass the hot gas to the evaporator 4, and blows out the evaporator 4 by opening and closing the hot gas valve 10. A refrigeration device for controlling air temperature,
It includes a supply sensor SS that detects the temperature of the air blown out of the evaporator 4, a return sensor RS that detects the temperature of the intake air of the evaporator 4, and an air temperature setting device 21, and the set temperature by the setting device 21. and the blowing air temperature detected by the supply sensor SS and the suction air temperature detected by the return sensor RS, and outputting an opening/closing signal to the hot gas valve 10 based on the comparison result between the set temperature and the blowing air temperature. Output means 2
3, a switching means 25 for switching the comparison between the blowing air temperature and the set temperature by the comparison means 22 to a comparison between the suction air temperature detected by the return sensor RS and the set temperature during pulldown; When the comparison is switched between the suction air temperature and the set temperature, the output means 23 stops outputting the opening/closing signal to the hot gas valve 10, and the comparison is made based on the comparison result between the suction air temperature and the set temperature by the comparison means 22. The controller 20 has a pull-down operation control means 24 that performs a pull-down operation and stops the pull-down operation when the temperature of the intake air reaches a temperature difference between the set temperature and the temperature for stable operation. Refrigeration equipment.