JPH0543940B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a refrigeration system.

In general, container refrigeration equipment operates in two modes: a freezing operation that controls the internal temperature of the container to a freezing range of -5°C to -6°C or lower, and a refrigeration operation that controls the internal temperature of the container to a chilled range that is higher than -5°C to -6°C. For this reason, the capacity of container refrigeration equipment is designed to the required refrigeration capacity during refrigeration operation, for example, the capacity to maintain the internal temperature at -18℃ when the outside temperature is 38℃. .

Therefore, when performing a refrigeration operation that maintains the internal temperature in the chilled region, the capacity is too high under conditions where the outside temperature is low, causing the problem that the desired internal temperature cannot be maintained.

In order to solve the above-mentioned problems, a method has been proposed in which a hot gas bypass pipe is inserted between the high-pressure gas pipe and the low-pressure liquid pipe to guide the hot gas to the evaporator to control the temperature inside the refrigerator. ing.

This conventional type of refrigeration equipment is
3692100 specification and drawings, and also No. 5
As shown in the figure, the condenser C ₁ and the condenser C ₁ are connected in series in the middle of the high-pressure gas pipe B that connects the discharge side of the compressor A and the inlet side of the air-cooled condenser C ₁ . A hot gas bypass pipe H bypassing the water-cooled condenser C ₂ , dryer R, and expansion valve EV is connected, and this hot gas bypass pipe H is connected to the expansion valve EV.
A temperature control valve connected to the low pressure liquid pipe D connecting the outlet side of the EV and the inlet side of the evaporator E, and equipped with a solenoid valve SV and a sensor T for detecting the temperature of the blown air, in the hot gas bypass pipe H. It is equipped with a TV, and the temperature inside the refrigerator in the chilled area can be controlled by controlling the temperature of the blowing air by hot gas bypass.

That is, when performing refrigeration operation, the solenoid valve SV
is opened, and when the blowing air temperature is below a set value, the temperature control valve TV is opened to flow the hot gas into the low pressure liquid pipe D, where it is combined with the liquid refrigerant that has passed through the expansion valve EV and introduced into the evaporator E; The temperature of the blown air is adjusted to keep the temperature inside the refrigerator in the chilled range.

However, according to the conventional device as described above, when the set temperature inside the refrigerator is low, or even if the set temperature is high but the outside temperature is higher than that, the hot gas bypass described above lowers the temperature inside the refrigerator. However, when the set temperature is set high and the outside temperature becomes lower than the set temperature, the temperature control valve TV and solenoid valve SV are activated to bypass the hot gas. Even if it is accomplished,
A problem arises in that the temperature inside the refrigerator cannot be controlled to the set temperature.

The first reason for this is that since the expansion valve EV is usually a temperature-sensitive expansion valve, as the outside temperature decreases, the opening degree of the solenoid valve SV increases.
The bypass amount of hot gas increases, and due to this increase in hot gas amount, the low pressure gas refrigerant on the outlet side of the evaporator E eventually becomes superheated gas, and for this reason, the low pressure gas pipe G is equipped with a temperature sensing part. The opening degree of the expansion valve EV will instead increase, and as a result, even if the outside temperature drops, the required amount of liquid refrigerant supplied to the evaporator E will not decrease or will instead increase. The second reason is that when the outside air temperature drops significantly, the ambient temperature of the air-cooled condenser C ₁ usually drops, and the water used in the water-cooled condenser C ₂ (e.g. As a result, the condensing pressure (temperature) of the condensers C ₁ and C ₂ decreases, and as a result, the discharge pressure (high pressure) of compressor A and the discharge temperature decrease. In other words, this is thought to be due to a decrease in the temperature of the hot gas.

The present invention was devised in view of the above-mentioned conventional problems, and the object is to use an external pressure-equalizing type temperature-sensitive expansion valve and apply the pressure of hot gas to the temperature-sensitive expansion valve. By controlling the degree of opening and reducing the amount of liquid refrigerant passing through the expansion valve, and by controlling the condensing capacity by adjusting the capacity of the condenser, the temperature of the hot gas can be maintained at a high temperature. With these features, it is possible to widen the range of control of the internal temperature by the hot gas in the chilled region.

Accordingly, the configuration of the present invention is such that in a refrigeration system equipped with a compressor, a condenser, an evaporator, and a temperature-sensitive expansion valve having a pressure equalizing pipe, hot gas discharged from the compressor is transferred between the condenser and the temperature-sensitive expansion valve. Bypassing the thermal expansion valve,
providing a hot gas bypass path leading to the evaporator;
A hot gas valve is interposed in the hot gas bypass passage, and a control passage is connected to the pressure equalization pipe in the hot gas bypass passage on the outlet side of the hot gas valve, and controls the opening degree of the expansion valve by the hot gas pressure. and the condenser is provided with a capacity adjusting means for adjusting the condensing capacity of the condenser, and a detector 12 is provided for detecting the condensing capacity of the condenser,
The capacity adjusting means is actuated based on the detection result of the detector 12 to control the condensing capacity of the condenser, and when the hot gas is bypassed, the opening degree of the expansion valve is controlled using the pressure of the hot gas. In addition to reducing the amount of liquid refrigerant passing through the expansion valve, the condensing capacity of the condenser is controlled to maintain a high temperature of the hot gas, thereby making it possible to expand the control range of the temperature of the blown air by the hot gas.

Next, an embodiment of the present invention will be described based on FIG.

In Fig. 1, 1 is a compressor, 2 is an air-cooled condenser,
3 is a water-cooled condenser, 4 is an evaporator, and 5 is a temperature-sensitive expansion valve having a pressure equalization pipe 51 and a temperature-sensing section 52, and these devices are connected by refrigerant piping 6, respectively.
The evaporator 4 forms a refrigeration cycle that cools the air inside the refrigerator.

In FIG. 1, 7 is an integrated accumulator receiver, 8 is a dryer, 9 is a solenoid valve for pump down, 10 is a liquid indicator, and 11
is a flow divider, and F ₁ and F ₂ are fans attached to the evaporator 4.

In the refrigeration cycle configured as described above, the high pressure gas pipe 6a connecting the discharge side of the compressor 1 and the inlet side of the air-cooled condenser 2 is connected to the compressor 1.
The hot gas discharged from each condenser 2,
3. Connect a hot gas bypass path 20 that bypasses the liquid receiver of the accumulator liquid receiver 7 and the temperature-sensitive expansion valve 5 to the evaporator 4, and connects the outlet side thereof to the expansion valve 5 and the evaporator 4. A hot gas valve 21 is interposed in the middle of this hot gas bypass path 20, and the hot gas bypass path 20 on the outlet side of the hot gas valve 21 is connected to the refrigeration cycle. low pressure gas pipe 6 in
A control passage 22 is provided which is connected to the pressure equalizing pipe 51 of the expansion valve 5 connected to c and which controls the opening degree of the expansion valve 5 using hot gas, and in this control passage 22,
A communication cutoff valve 23 is provided to cut off communication between the hot gas bypass path 20 and the pressure equalization pipe 51.

The hot gas valve 21 may be an electromagnetic valve with an on/off function, but mainly an electromagnetic proportional control valve that can control the valve opening from 0% to 100% in proportion to the voltage is used. It is done as if controlled by.

The communication cutoff valve 23 mainly uses a three-way switching valve as shown in FIG. The pressure pipes 51a are connected to each other, and a second pressure equalization pipe 51b is connected to the fixed port, so that the second pressure equalization pipe 51b communicating with the pressure equalization part of the expansion valve 5 is connected to the control passage 22 and the first pressure equalization pipe 51.
This is done as if switching to a.

Furthermore, the outlet side of the hot gas bypass path 20 is connected to the low pressure liquid pipe 6b as described above, and the connection position is not limited;
Preferably, it is connected to the flow divider 11.

The air-cooled condenser 2 also has motors 14a, 14b, and
Three fans F ₃ , F ₄ , F ₅ with 14c are provided,
In detail, as described later, one motor 14
A and the other two motors 14b and 14c can be independently controlled. This constitutes a capacity adjustment means for the condenser 2, and by reducing the number of operating fans F ₃ , F ₄ , F ₅ to three or one, the condenser 2 can be adjusted. It is possible to increase or decrease the condensation capacity of.

Further, on the discharge side of the compressor 1, there is provided a detector 12 consisting of a high pressure switch HPS that detects the condensing pressure of the condenser 2, that is, the high pressure. The condensing capacity of the condenser 2 is detected, and the capacity adjusting means of the condenser 2 is controlled by a controller 24, which will be described later, based on the detection result.

Next, the hot gas valve 21 and the communication cutoff valve 23
The electrical circuit of the refrigeration system, which has a controller 24 that controls the temperature of the blown air and adjusts the temperature of the blown air to a desired temperature, and operates each electrical device, will be described with reference to FIG.

What is shown in Fig. 2 is the electric circuit of the refrigeration system shown in Fig. 1, in which the compressor motor is
MC, two fans F ₁ attached to the evaporator 4,
A parallel circuit of the motors 13 and 13 of _F2 , and one of the three fans _F3 to _F5 provided in the air-cooled condenser 2.
Connect the parallel circuits of the motor 14a of the fan F ₃ and the motors 14b and 14c of the other two fans F ₄ and F ₅ , respectively, and draw out two power lines from the three-phase power line, The controller 24 and the control relay circuit of the electrical device are connected to this power line via a switch SW and a fuse Fu.

That is, a high and low pressure switch HLPS is installed between the power lines.
A series circuit of overcurrent relay OC and relay 88c for compressor motor MC, and a fan installed in evaporator 4.
Relay R ₁ for motors 13, 13 of F ₁ and F ₂ , and further,
Fans F ₃ , F ₄ , F ₅ provided in the air-cooled condenser 2
Among the motors 14a, 14b, 14c, a parallel circuit of relay _R2 for one motor 14a and relay _R3 for the other two motors 14b, 14c is connected, while the output terminal of the controller 24 The electric part 20M of the hot gas valve 21 and the relay 2X
A series circuit between the solenoid relay ^20S1 of the communication cutoff valve ₂₃ and the normally open contact 2X- ² of the relay 2X, and a solenoid valve 9 connected in parallel to this series circuit. Connect the solenoid relay 20S ₂ and the relay 2X, and further,
The detector 12, which is a high pressure switch HPS that detects the high pressure of the air-cooled condenser 2, is connected in series with the relay _R3 and in parallel with the relay _R2 . The detector 12 opens when the pressure becomes lower than a preset high pressure, and opens when the pressure becomes higher than the preset high pressure.

In addition, A is a contact point of a switching relay that switches the control by the controller 24 between refrigeration operation and freezing operation, B is a contact point of a relay that turns ON and OFF when the compressor 1 starts and stops, and SS and RS are contacts during refrigeration and freezing operation. They are a supply sensor and a return sensor that selectively act to detect the temperature of the air blown out or sucked into the evaporator 4, respectively.

Further, the controller 24 closes the contact A of the switching relay, thereby controlling the relay 2X.
The solenoid relay _20S1 is energized, the communication cutoff valve 23 is operated, and the control passage 22 is switched to communicate with the second pressure equalizing pipe 51b.
0M is set to the operable state, the preset temperature SETT input in advance is compared with the internal temperature SUPT detected by the supply sensor SS, and a control signal is output to the electric part 20M of the hot gas valve 21, and the valve 21 The opening degree of the valve is controlled as described later to enable refrigeration operation, and by opening the contact A of the switching relay, the relay 2X and the solenoid relay _20S1 are demagnetized, and the hot gas The motorized part 20M of the valve 21 is made inoperable, and the return sensor RS is activated to control the refrigeration operation.

The operation of the refrigeration system constructed as described above will be explained based on the flowchart shown in FIG.

First, a case will be described in which the switch SW is closed and the contact A of the changeover relay is closed to perform the refrigeration operation.

When the switch SW is closed, operation is started according to the flow of () and () below.

() Relays 88c, R ₁ and R ₂ are energized, and the contacts of each relay 88c, R ₁ and R ₂ are closed,
Compressor motor MC, fan installed in evaporator 4
Motors 13, 13 for F ₁ and F ₂ , and one fan among the three fans F ₃ to F ₅ installed in the condenser 2.
As the motor 14a of _F3 is driven, the relay 2X is energized, and the normally open contacts 2X- ¹ , 2X
- ² is closed, and as a result, the communication cutoff valve 23 is switched to connect the control passage 22 and the second pressure equalizing pipe 51b, and the blowing air temperature SUPT detected by the supply sensor SS is applied to the electric part 20M. A control signal is output by comparing the set temperature SETT and the set temperature SETT, and control of the opening degree of the hot gas valve 21 is started.

As a result, the blowing air temperature SUPT becomes the set temperature SETT
In the following cases, the control signal to the electric part 20M becomes high, the opening degree of the hot gas valve 21 increases, and the bypass amount of hot gas via the hot gas bypass path 20 increases; Air temperature SUPT and set temperature SETT
When they are equal, the opening degree of the hot gas valve 21 is held constant, and the blowing air temperature SUPT is equal to the set temperature SETT.
When higher, the control signal is lower;
The opening degree of the hot gas valve 21 is reduced, and the bypass amount of hot gas is reduced.

Furthermore, at the same time, the hot gas valve 21
During the opening operation, the hot gas flowing through the hot gas bypass passage 20 also acts on the second pressure equalizing pipe 51b of the expansion valve 5 at a pressure corresponding to the valve opening degree, causing the expansion valve 5 to This means that the valve opening will be limited to the one that corresponds to the pressure.

Therefore, the amount of liquid refrigerant passing through the expansion valve 5 decreases in accordance with the valve opening degree, and a desired flow rate of hot gas is guided to the evaporator 4 via the flow divider 11. Heating with hot gas is possible with the refrigerating capacity reduced by reducing the opening of the valve, and by bypassing the hot gas, the temperature of the blown air can be controlled with high accuracy and over a wide range.

() In parallel with the operation in () above, the detector 12 operates by detecting the high pressure of the air-cooled condenser 2, so that the high pressure _P1 of the air-cooled condenser 2 is set to the set high pressure P. When the value is ₀ or more, the detector 12 is closed, the relay R ₃ is energized, and the contact R ₃ is energized.
The motors 14a, 14b, and 14c of the three fans _F3 , _F3 , and _F4 provided in the air-cooled condenser 2 are thereby driven, and the high pressure of the air-cooled condenser 2 is also closed. When the pressure P ₁ is lower than the set high pressure P ₀ , the detector 12
is opened, the relay R ₃ is demagnetized, and the contact R ₃
was also developed, and two of the three motors 1
4b and 14c are stopped.

As described above, when the high pressure of the air-cooled condenser 2 falls below the set high pressure, the fans F ₄ and F ₅ are stopped, so the outside air temperature and therefore the ambient temperature of the air-cooled condenser 2 are reduced. Despite the decrease in T ₁ , the condensing pressure, and hence the high pressure, can be kept high, and as a result, the hot gas can also be kept at a high temperature, that is, the heating ability of the hot gas can be kept high.

Furthermore, since the high pressure can be maintained high, the pressure of the hot gas acting on the expansion valve 23 via the control passage 22 can also be maintained high, so even if the outside air temperature decreases and the high pressure decreases. This prevents the pressure of the hot gas from decreasing and the control range of the expansion valve 5 in the throttle direction to be greatly restricted.

What is shown in FIG. 4 shows the control characteristics of the outlet air temperature SUPT with respect to the outside air temperature of the condenser 2, and the area indicated by () and () is the control area of this embodiment, and the area () shows the control range of the conventional one.

Next, a case will be briefly described in which the contact A of the switching relay of the controller 24 is opened to perform the refrigeration operation.

When contact A of the switching relay is opened, the relay 2X is demagnetized and the normally open contacts 2X- ¹ and 2X- ² are opened.
is opened, and as a result, the communication cutoff valve 23 provided in the control passage 22 is switched to communicate the first pressure equalizing pipe 51a and the second pressure equalizing pipe 51b,
By closing the hot gas valve 21, normal refrigeration operation can be performed. Also in this refrigeration operation, when the high pressure decreases due to a decrease in outside air temperature, the detector 12 activates to shut down the two fans for the air-cooled condenser 2.
High pressure control is possible by stopping F ₄ and F ₅ .

In the above embodiment, the capacity adjustment means provided in the condenser 2 are motors 14a, 14b,
It was composed of fans F ₃ to F ₅ with 14c,
One fan may be used and the motor of this fan may be controlled at two speeds, high and low, by a pole change, or a motor with a frequency converter may be used to control the rotation speed steplessly. You can do it as you like.

Further, in the above embodiment, only the air-cooled condenser 2 among the condensers has a variable capacity, but the water-cooled condenser 3 may also have a variable capacity. In this case, in order to supply water to the water-cooled condenser 3, The motors 14a, 14b of the fans _F3 to _F5 ,
By making the capacity variable similarly to 14c, a capacity adjustment means is constructed.

Furthermore, the embodiment described above is based on the high pressure pressure switch HPS.
The high pressure of the condenser 2 is detected by a detector 12 consisting of a
However, the high pressure corresponding to the condensing pressure fluctuates almost equivalently to the condensing temperature, and the condensing pressure changes depending on the outside air temperature. Since the condensing capacity of the condenser 2 is determined, for example, a temperature switch that detects the condensing temperature may be used as the detector, or a temperature switch that detects the outside air temperature may be used as the detector. The present invention is not limited to a high-pressure switch that detects high pressure as long as it has a configuration that can detect the capability.

As described above, the present invention includes a temperature-sensitive expansion valve 5 in the hot gas bypass passage 20 on the outlet side of the hot gas valve 21.
A control passage 22 is provided which is connected to the pressure equalizing pipe 51 of the hot gas valve 21 and controls the opening degree of the expansion valve 5 using hot gas. Since the control is performed based on the pressure of the expansion valve 5, the amount of liquid refrigerant passing through the expansion valve 5 can be reduced.
The condensing capacity of the condensers 2 and 3 can be adjusted, and a detector 12 for detecting the condensing capacity of the condenser 2 is provided, and the capacity adjusting means is actuated based on the detection result of this detector 12. Since the condensing capacity of the condenser 2 is controlled, the high pressure can be maintained at a high level even if the outside temperature drops.
The hot gas can be maintained at a high temperature, which improves control accuracy using the hot gas, and also allows hot gas to be blown out even when the heat load is low, such as when the set temperature is high or when the outside air temperature is lower than the set temperature. The air temperature can be controlled. In other words, the range of control of the internal temperature using hot gas in the chilled region can be expanded, and the range of possible operation at a high set temperature even under particularly low outside air temperatures can be expanded.

[Brief explanation of the drawing]

Fig. 1 is a refrigerant piping system diagram showing one embodiment of the refrigeration system of the present invention, Fig. 2 is an electric circuit diagram of the refrigeration system shown in Fig. 1, and Fig. 3 is a diagram of the refrigeration system shown in Fig. 1. FIG. 4 is a flowchart showing the operating conditions, FIG. 4 is a control characteristic diagram of the temperature of the blown air relative to the outside temperature, and FIG. 5 is a refrigerant piping system diagram showing a conventional example. 1... Compressor, 2, 3... Condenser, 4... Evaporator, 5... Temperature-sensitive expansion valve, 11... Flow divider, 12...
...Detector, 20...Hot gas bypass path, 21
... Hot gas valve, 22 ... Control passage, 51 ...
pressure equalization tube.

Claims (1)

[Claims] 1 In a refrigeration system equipped with a compressor 1, condensers 2 and 3, an evaporator 4, and a temperature-sensitive expansion valve 5 having a pressure equalization pipe 51, hot gas discharged from the compressor 1 is transferred to the condensers 2 and 3. and a temperature-sensitive expansion valve 5, and a hot gas bypass path 2 leading to the evaporator 4.
0, a hot gas valve 21 is interposed in the hot gas bypass path 20, and the pressure equalizing pipe 51 is connected to the hot gas bypass path 20 on the outlet side of the hot gas valve 21, so that the hot gas pressure
A control passage 22 for controlling the opening degree of the expansion valve 5 is provided, and a capacity adjusting means for adjusting the condensing capacity of the condenser 2 is provided in the condenser 2, and the condensing capacity of the condenser 2 is detected. A detector 12 is provided,
The refrigeration system is characterized in that the capacity adjusting means is actuated based on the detection result of the detector 12 to control the condensing capacity of the condenser 2.