JP2001027466A - Refrigerating unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent abnormal stop of a refrigerating unit due to action of a high pressure switch acting with high delivery pressure of a compressor at the time of restart by preventing the deliver pressure of the compressor from exceeding a set level of the high pressure switch when the refrigerating unit is restarted. SOLUTION: The refrigerating unit comprise a compressor 3 compressing refrigerant for cooling or heating circulation air for keeping an appropriate temperature in a freezer to produce high temperature high pressure gas refrigerant, a solenoid valve 6 positioned at the inlet of a condenser 4 and opened, at the time of cooling, to introduce the gas refrigerant into the condenser 4, and a hot gas bypass solenoid valve 7 positioned at the inlet of an evaporator 10 and opened, at the time of heating the circulation air, to introduce high temperature high pressure gas refrigerant to the evaporator 10 and also opened, at the time of cooling the circulation air, to introduce gas refrigerant to the evaporator for a predetermined time and then closed to bring about normal operation for cooling the circulation air.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant temperature suitable for maintaining freshness of fresh foods or the like, which is loaded on a truck or the like used for transporting fresh foods or the like and is transported. The present invention relates to a sub-engine type land transportation refrigeration unit (hereinafter simply referred to as a refrigeration unit) for controlling the temperature to a predetermined temperature.

[0002]

2. Description of the Related Art In order to prevent quality deterioration during transportation of freight such as fresh foods transported between remote locations, the freight is maintained at an appropriate temperature suitable for maintaining the freshness of the freight. Transport between the grounds is taking place. For this purpose, transportation by a vehicle equipped with a refrigeration unit capable of freely controlling the temperature in a cargo compartment (hereinafter, referred to as a freezer in the present specification) is performed.

FIG. 3 is an overall view of a vehicle equipped with such a refrigeration unit and capable of controlling the temperature in a freezer for storing the cargo to be transported to a temperature suitable for the stored cargo. As shown in the drawing, the refrigeration unit mounted on the vehicle includes a condensing unit 1 installed below the outside of the freezer 100 and an evaporator unit 2 installed above the front end of the freezer 100. And the evaporator unit 2 are connected by refrigerant pipes 40, 50 and 60.

FIG. 4 is a view schematically showing components of the condensing unit 1 and the evaporator unit 2 constituting the refrigeration unit shown in FIG. As shown in FIG. 4, inside the condensing unit 1 installed below the freezer 100,
A compressor 3 is provided, and is driven by power of an engine (not shown).

When the high-pressure, high-temperature gas refrigerant adiabatically compressed by the compressor 3 cools the freezer 100, the condenser inlet solenoid valve 6 is controlled to open and the hot gas bypass solenoid valve 7 is controlled to close. Is cooled by the outside air introduced by the condenser fan 5 and condensed and liquefied.

The condensed and liquefied refrigerant flows out of the condenser 4, passes through a refrigerant pipe 40 connecting the condensing unit 1 and the evaporator unit 2 installed in the freezer 100, and then an expansion valve 12 arranged in the evaporator unit 2. And is adiabatically expanded by the action of the expansion valve 12 and flows into the evaporator 10. The refrigerant flowing into the evaporator 10 removes the heat of the air circulating in the freezer 100 sent into the evaporator 10 by the evaporator fan 11, thereby cooling the circulating air and keeping the inside of the freezer 100 at a low temperature.

[0007] That is, the circulating air sent into the evaporator 10 by the evaporator fan 11 is deprived of heat by the latent heat of evaporation of the refrigerant adiabatically expanded by the expansion valve 12 and cooled, and then again by the evaporator fan 11 to the evaporator unit 2. Is blown out into the freezer 100 from a not-shown outlet provided in the refrigerator 100, circulates in the freezer 100 as cooled and cooled circulating air, and cools the cargo in the freezer 100 to a temperature suitable for maintaining freshness. Hold.

[0008] Further, in the evaporator 10, the gas refrigerant which has taken heat from the circulating air in the freezer 100 and which has been sent into the evaporator 10 and evaporates is supplied to a refrigerant pipe 50 connecting the evaporator unit 2 and the condensing unit 1.
, Is returned to the compressor 3 via the suction pressure regulating valve 8 arranged in the condensing unit 1, and is further adiabatically compressed to repeat the above-described cooling step.

On the other hand, when heating the circulating air in the freezer 100 to a temperature suitable for the stored cargo, the condenser inlet solenoid valve 6 is closed and the hot gas bypass solenoid valve 7 is opened to control the temperature. Is performed. That is, the gas refrigerant which has been adiabatically compressed by the compressor 3 to have a high pressure and a high temperature passes through the hot gas bypass solenoid valve 7 and after the condensing unit 1 and the expansion valve 12 of the evaporator unit 2 installed in the freezer 100. The refrigerant enters the evaporator 10 at a high temperature, bypassing the expansion valve 12 via the refrigerant pipe 60 connecting the flow side, where the evaporator fan 1
Freezer 10 sent to evaporator 10 by 1
Heat is exchanged with the circulating air in the chamber 0 to heat the circulating air.

[0010] The heated circulating air is blown into the freezer 100 from an outlet (not shown) of the evaporator unit 2 by the evaporator fan 11, and circulates inside the freezer 100 as heated circulating air. Heat the cargo to bring it to the right temperature. Further, the evaporator 10 exchanges heat with the circulating air in the freezer 100, and the refrigerant whose temperature has decreased is condensed and liquefied, and the refrigerant piping 50
Through the suction pressure regulating valve 8 in the condensing unit 1
, And returns to the compressor 3 as a gas refrigerant, is further adiabatically compressed, and repeats the above-described heating step.

A high-pressure switch 9 is provided in the middle of the high-pressure, high-temperature gas refrigerant side pipe which is discharged from the compressor 3 and supplied to the condenser inlet solenoid valve 6 or the hot gas bypass solenoid valve 7. When the pressure exceeds a preset pressure, for example, about 3.0 MPa, the high pressure switch 9 is operated to abnormally stop the refrigeration unit.

FIG. 5 shows the freezer 100 as described above.
FIG. 4 is a diagram showing a control flow for cooling or heating the circulating air to make the temperature inside the freezer 100 appropriate for keeping freshness of cargo stored in the freezer 100 and the like.

As shown in the figure, at the same time as the operation of the refrigeration unit is started, the circulating air needs to be cooled or heated by the operation mode determiner 13 in order to reach the temperature required for maintaining the freshness of the cargo. The operation mode of the refrigeration unit is determined, and if cooling is necessary, the condenser inlet solenoid valve 6 shown in FIG. 4 is opened and the hot gas bypass solenoid valve 7 is closed to perform heating. If there is
By controlling the condenser inlet electromagnetic valve 6 to be closed and the hot gas bypass electromagnetic valve 7 to be opened, the circulating air in the freezer 100 is cooled or heated so that the temperature in the freezer 100 is optimal for maintaining the freshness of the stored cargo. Temperature.

Next, FIG. 6 shows the pressure change after the start of the cooling operation when the cooling operation by the refrigeration unit is required by the above-mentioned operation mode judging device 13, that is, the pressure is discharged from the compressor 3 shown in FIG. It is a figure showing a change of a refrigerant pressure. As shown in the figure, the pressure of the refrigerant discharged from the compressor 3 immediately after the start of the cooling operation temporarily rises suddenly, then decreases as the operation progresses, and becomes steady and stable.

For this reason, in the above-mentioned conventional refrigeration unit, when the temperature of the outside air introduced by the condenser fan 5 during the cooling operation is high, the condensation capacity of the condenser 4 is reduced, and the pressure on the discharge side of the compressor 3 is reduced. High pressure switch 9 during operation.
Does not operate and the refrigeration unit does not stop abnormally.

However, once the refrigeration unit is stopped, the liquid refrigerant remaining in the condenser 4 and the refrigerant from the outlet of the condenser 4 to the expansion valve 12 which is automatically throttled when the refrigeration unit is stopped. Since the liquid refrigerant in the pipe 40 makes it difficult for the high-pressure gas refrigerant to flow into the condenser 4 when the compressor 3 starts, the pressure on the discharge side of the compressor 3 temporarily increases immediately after the start of the cooling operation,
The set pressure value of the high pressure switch 9 is set to, for example, 3.0 MPa.
Overshoot of about 0.2 MPa may occur, which causes a problem that the high-pressure switch 9 is activated and the refrigeration unit is abnormally stopped.

As a means for solving such a problem, the capacity of the condenser 4 is increased to increase the condensing capacity, the pressure on the discharge side of the compressor 3 during the operation of the refrigeration unit is reduced, or the capacity of the condenser fan 5 is increased. By increasing the condensing capacity and lowering the pressure on the discharge side of the compressor 3 during the operation of the refrigeration unit, even if there is an increase in the pressure on the discharge side of the compressor 3 immediately after the start of the operation of the compressor 3, the high-pressure pressure switch setting value HPs
To prevent the high pressure switch 9 from operating.

However, in this way, if the abnormal stop of the refrigerating unit due to the operation of the high-pressure switch 9 which may occur when the compressor 3 is started after the stop has been stopped is prevented, the capacity of the condenser 4 is increased. In the means, the size of the refrigeration unit is increased due to the increase in the size of the condensing unit 1, which leads to an increase in weight and cost. In addition, the elimination means in which the capacity of the condenser fan 5 is increased to increase the amount of outside air includes: In addition to the increase in weight and cost described above, there is a problem that noise increases.

[0019]

SUMMARY OF THE INVENTION The present invention is directed to a high-pressure pressure which is caused by an overshoot of a compressor discharge pressure exceeding a high-pressure pressure switch set value which occurs when a refrigeration unit during a cooling operation is temporarily stopped and restarted. In order to eliminate the malfunction of the conventional refrigeration unit, which may cause the refrigeration unit to stop abnormally due to the operation of the switch, the size of the condensing unit must be increased due to an increase in the capacity of the condenser and the condenser fan. Compressor discharge pressure exceeding the high pressure switch setting, which occurs when the refrigeration unit is restarted once, without increasing the weight and cost, and without increasing the noise level generated by the condenser fan etc. during operation Compressor discharge pressure at restart By the high-pressure pressure switch actuated actuated by high pressure, and to provide a refrigeration unit that can prevent the abnormal stop of the refrigeration unit.

[0020]

Therefore, the refrigerating unit of the present invention has the following means.

(1) circulating air circulating in the freezer to cool the cargo stored in the freezer to an appropriate temperature;
Alternatively, the condenser unit is provided with a compressor that recovers the heated refrigerant from the evaporator unit, compresses the refrigerant, converts the refrigerant into a high-temperature, high-pressure gas refrigerant, and discharges the refrigerant to the condenser or the evaporator according to cooling or heating of the circulating air.

(2) It is interposed between the compressor discharge port and the condenser, and is opened when cooling the circulating air, and is cooled from the compressor discharge port to the condenser for cooling and condensing and liquefying the high-temperature high-pressure gas refrigerant. A solenoid valve at the inlet of the condenser to introduce a gas refrigerant in a high-temperature and high-pressure state is provided.

(3) It is interposed between the compressor discharge port and the evaporator and is opened when heating the circulating air, and a high-temperature, high-pressure gas refrigerant from the compressor discharge port is introduced into the evaporator to remove the circulating air. When heating and cooling the circulating air, it is opened together with the condenser inlet solenoid valve, which is opened when the compressor is started, and introduces a high-temperature, high-pressure gas refrigerant from the compressor discharge port to the evaporator for a predetermined time. A hot gas bypass solenoid valve, which is closed after a predetermined time has passed, shuts off the introduction of the high-temperature, high-pressure gas refrigerant into the evaporator, and sets an operation state for cooling the normal circulating air, is provided.

The opening time of the hot gas bypass solenoid valve, which is opened when the circulating air is heated and opened when the compressor is started also when the circulating air is cooled,
The so-called predetermined time during which the hot gas bypass solenoid valve is opened when cooling the circulating air naturally depends on the design conditions of the refrigeration unit, but it is 1 minute or less, preferably 10 minutes or less.
It is preferable to set the time to about seconds.

The refrigeration unit according to the present invention is characterized in that
Since the means of (3) is adopted, when the refrigeration unit is once stopped and then restarted to cool the circulating air, by opening the condenser inlet solenoid valve and the hot gas bypass solenoid valve, Some of the high-temperature, high-pressure gas refrigerant discharged from the compressor is not used for cooling the circulating air, but rather heats the circulating air, but is introduced into the condenser because it is introduced into the evaporator. The flow rate of the gas refrigerant from the compressor can be reduced, the pressure of the high-temperature and high-pressure gas refrigerant discharged from the compressor is reduced, and the pressure of the high-temperature and high-pressure gas refrigerant discharged from the compressor is reduced by the compressor discharge port and the condenser. Exceeds the pressure setting of the high pressure switch interposed between the inlet solenoid valve and the hot gas bypass solenoid valve Eliminates the bets occurs, it is possible to prevent the abnormal stop of the refrigeration unit by the operation of the high pressure switch.

Further, in order to prevent the pressure of the gas refrigerant in the high temperature and high pressure state discharged from the compressor from exceeding the pressure set value of the high pressure switch, the capacity of the conventionally used condenser and condenser fan is increased. This eliminates the need to increase the size, size and size of the condensing unit, resulting in an increase in weight, cost, and running cost, and increases the noise level associated with the increase in the size of the condenser fan. Disappears.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a refrigeration unit of the present invention will be described below with reference to the drawings. In the drawings, the same or similar members as those shown in FIGS. 3 to 6 are denoted by the same reference numerals, and description thereof is omitted as much as possible.

FIG. 1 is a view showing a first embodiment of a refrigeration unit according to the present invention. In the same manner as shown in FIGS. FIG. 3 is a diagram showing a control flow for setting the temperature inside the refrigerator to a temperature appropriate for the cargo carried in the freezer 100.

As shown in the figure, in the present embodiment, at the same time when the operation of the refrigeration unit is started, the circulating air that causes the operation of the refrigeration unit to circulate in the freezer 100 is stored in the freezer 100 at the operation mode determiner 13. Then, the operation mode of cooling or heating by the conveyed cargo is determined, and when the operation mode is determined to be the cooling operation mode, the condenser inlet solenoid valve 6 and the hot gas bypass solenoid valve 7 are opened. The hot gas bypass solenoid valve 7 is provided with a timer or the like that outputs a signal for closing the hot gas bypass solenoid valve 7 when a preset predetermined time has elapsed after the start of driving of the compressor 3. A control device for controlling the opening and closing of the omitted hot gas bypass solenoid valve 7 is provided.

Since the refrigeration unit of the present embodiment is configured as described above, the operation mode of cooling or heating is determined at the same time as the operation of the refrigeration unit is started.
When the operation mode is determined to be the cooling operation mode, the hot gas bypass solenoid valve 7 is opened at the same time as the condenser inlet solenoid valve 6 is opened, as shown in FIG. Is compressed by the compressor 3
The discharged high-pressure gas refrigerant flows to the condenser 4 via the condenser inlet electromagnetic valve 6, and also flows to the evaporator 10 of the evaporator unit 2 via the refrigerant pipe 60 via the hot gas bypass electromagnetic valve 7.

As a result, the elapsed time t after the start of operation is t
2 shows the relationship between the pressure and the gas refrigerant pressure HP discharged from the compressor 3. As shown in FIG. 2, the gas refrigerant pressure HP temporarily increases immediately after the start of operation and becomes a high pressure. Only the amount of the gas refrigerant flowing into the evaporator 10 via the hot gas bypass solenoid valve 7 is reduced at least, and does not exceed the high pressure switch setting value HPs, and the high pressure switch 9 does not operate. Therefore, it is possible to eliminate the abnormal stop of the refrigeration unit which may be caused by the operation of the high pressure switch 9.

That is, according to the refrigeration unit of this embodiment, the components of the condensing unit 1 and the evaporator unit 2 and the refrigerant pipes are not changed, and the temporary increase in the high pressure immediately after the cooling operation is started. The operation of the high pressure switch 8 can be avoided. Thereafter, a predetermined time determined by a test or the like, for example, 1
After a lapse of 0 sec, a signal for closing the hot gas bypass solenoid valve 7 is output from the control device, so that the hot gas bypass solenoid valve 7 is closed and normal cooling operation can be performed.

When the hot gas bypass solenoid valve 7 is closed after the predetermined time, as shown in FIG. 2, the gas refrigerant pressure HP rises for a predetermined time. By the time the hot gas bypass solenoid valve 7 is closed, for example, 10
Since the second time has elapsed, the liquid refrigerant remaining in the condenser 4 and the liquid refrigerant in the refrigerant pipe 40 from the condenser 4 to the expansion valve 12 make it difficult for the liquid refrigerant to flow when the compressor 3 is started. The expansion valve 12, which was in the throttled state when the refrigeration unit was stopped, is changed from the throttled state to the open state, and is in an operating state in which the liquid refrigerant is allowed to pass to perform adiabatic expansion. The rise of the gas refrigerant pressure HP accompanying the stagnation of the hot gas bypass solenoid valve 7 is suppressed.
The rise of the gas refrigerant pressure HP will not cause the high pressure switch setting value HPs to be exceeded, and the high pressure switch 9 will not cause an abnormal stop of the refrigeration unit due to the operating state.

As described above, according to the refrigeration unit of the present embodiment, the condenser inlet solenoid valve 6 and the hot gas bypass solenoid valve 7 are opened simultaneously with the start of operation of the refrigeration unit performing the cooling operation. When a predetermined period of time has elapsed after the start of the operation of the compressor 3, the high-pressure gas refrigerant compressed and discharged by the compressor 3 by closing the hot gas bypass solenoid valve 7 is discharged from the condenser inlet electromagnetic valve. It flows to the condenser 4 via the valve 6 and also to the evaporator 10 of the evaporator unit 2 via the refrigerant pipe 60 via the hot gas bypass solenoid valve 7.

As a result, the pressure increase in which the gas refrigerant pressure HP temporarily increases immediately after the start of operation is reduced by the amount of the gas refrigerant flowing into the evaporator 10 via the hot gas bypass solenoid valve 7, and the high pressure switch is set. Value HP
s is not exceeded, the high-pressure switch 9 is not operated, and the abnormal stop of the refrigeration unit that may be caused by the operation of the high-pressure switch 9 can be eliminated.

Thereafter, after a predetermined time determined by a test or the like, for example, 10 seconds after the start of operation, a signal for closing the hot gas bypass solenoid valve 7 is output from the control device, so that the hot gas bypass solenoid valve is output. 7 is closed and normal cooling operation is performed.

When the hot gas bypass solenoid valve 7 is closed, the gas refrigerant pressure HP discharged from the compressor 3 also increases. However, the operation starts until the hot gas bypass solenoid valve 7 is closed. For example, the liquid refrigerant remaining in the condenser 4 and the liquid refrigerant in the refrigerant pipe 40 from the condenser 4 to the expansion valve 12 due to the lapse of the predetermined time, the expansion valve 12 opens the throttled state. Operating state and the adiabatic expansion of the liquid refrigerant by the evaporator 10, the gas refrigerant pressure HP
Is suppressed, and the hot gas bypass solenoid valve 7 is closed, so that the gas refrigerant pressure HP does not exceed the high pressure switch setting HPs, and the high pressure switch 9 is activated. It does not cause the refrigeration unit to stop abnormally.

In the above-described embodiment, the control device that closes the hot gas bypass solenoid valve 7 operates only in the cooling operation mode of the refrigeration unit, and does not operate in the heating operation mode. The closing operation of the hot gas bypass solenoid valve 7 is not performed. Further, the control device is a hot gas bypass solenoid valve 7.
Although an example in which the camera is mounted on the camera is shown, the present invention is not limited to such an embodiment.

[0039]

The refrigeration unit according to the present invention cools the circulating air circulated in the freezer or compresses the heated refrigerant in order to bring the cargo in the freezer to an appropriate temperature, so that the high-temperature, high-pressure gas refrigerant A compressor that discharges to a condenser or evaporator in response to cooling or heating of the cargo, is provided at the inlet of the condenser, is opened when cooling the circulating air, and is heated to a condenser that cools the introduced gas refrigerant and condenses and liquefies. A condenser inlet solenoid valve for introducing high-pressure gas refrigerant is provided at the inlet of the evaporator, and is opened when heating the circulating air.The high-temperature, high-pressure gas refrigerant is introduced into the evaporator to heat and cool the circulating air. When the compressor is operated, a part of the gas refrigerant discharged from the compressor is opened with the solenoid valve at the condenser inlet for a predetermined time. Introduced into porator, and closed after a predetermined time has elapsed, block the introduction into the evaporator, it was assumed to provide a hot gas bypass solenoid valve to the normal state to cool the circulating air.

In the refrigeration unit of the present invention, when the refrigeration unit is temporarily stopped and restarted by the above-described configuration, the condenser inlet solenoid valve and the hot gas bypass solenoid valve are opened, and the high temperature / high pressure state from the compressor is released. Part of the gas refrigerant can be introduced into the evaporator to reduce the flow rate of the gas refrigerant to the condenser, reduce the discharge pressure from the compressor, and reduce the discharge pressure from the compressor to the compressor outlet, condenser inlet solenoid valve and hot gas. It does not exceed the pressure set value of the high pressure switch provided between the bypass solenoid valve and the refrigeration unit.

Further, it is not necessary to increase the capacity of the condenser and the condenser fan to prevent the pressure of the high-temperature and high-pressure gas refrigerant discharged from the compressor from exceeding the pressure set value of the high-pressure switch. An increase in the size and cost of the condensing unit due to the increase in size can be avoided, and the increase in noise level due to the increase in the size of the condenser fan is also eliminated.

[Brief description of the drawings]

FIG. 1 is a view showing a first embodiment of a refrigeration unit according to the present invention, for cooling or heating circulating air in a freezer to bring the temperature in the freezer to an appropriate temperature for the contained transported cargo. Control flow diagram,

FIG. 2 is a diagram showing the relationship between the elapsed time after the start of operation and the refrigerant pressure according to the control flow chart shown in FIG. 1;

FIG. 3 is a cross-sectional view showing the entire vehicle loaded with a freezer;

4 is a diagram showing a schematic configuration of a condensing unit and an evaporator unit constituting a conventional refrigeration unit provided in the vehicle shown in FIG. 3, and a refrigerant pipe configuration;

FIG. 5 is a diagram showing a control flow of the refrigeration unit shown in FIG. 4,

6 is a diagram showing the relationship between the elapsed time from the start of operation according to the control flow shown in FIG. 5 and the refrigerant pressure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Condensing unit 2 Evaporator unit 3 Compressor 4 Condenser 5 Condenser fan 6 Condenser inlet solenoid valve 7 Hot gas bypass solenoid valve 8 Intake pressure regulation valve 9 High pressure switch 10 Evaporator 11 Evaporator fan 12 Expansion valve 13 Operation mode judgment device 40 Refrigerant piping 50 Refrigerant piping 60 Refrigerant piping 100 Freezer HPs High pressure switch setting HP refrigerant pressure

Claims (1)

[Claims] 1. A refrigeration unit for cooling or heating circulating air circulating in the freezer in order to maintain the cargo stored in the freezer at an appropriate temperature.
A compressor that cools the circulating air, or compresses a gas refrigerant to be heated, and discharges the refrigerant as a high-temperature, high-pressure refrigerant,
A condenser inlet solenoid valve that is opened when cooling the circulating air and introduces the high-temperature and high-pressure refrigerant into the condenser,
Opened when heating the circulating air, introduces the high-temperature / high-pressure refrigerant into the evaporator, and opens together with the condenser inlet solenoid valve when cooling the circulating air, and closes after a lapse of a predetermined time to close the high-temperature / high-pressure refrigerant. A refrigeration unit provided with a hot gas bypass solenoid valve for shutting off introduction into the evaporator.