JPH04103969A - Freezer - Google Patents

Abstract

PURPOSE:To avoid useless consumption of fuel and restrict any mechanical consumption of a starter or a stain of engine oil by a method wherein a long or short period of time for terminating an operation of a freezer is judged, and if the long period of time is found, an engine is stopped and in turn if the short period of time is found, the engine is set to an idling operation. CONSTITUTION:In the event that a temperature within a freezer 10 is decreased under a cooling operation and a freezer temperature Ti is less than a set lower limit temperature T2, a freezer temperature Ti and an outside temperature To are read. Then, it is judged if a temperature difference DELTAT between the outside temperature To and the freezer temperature Ti is less than a set temperature difference DELTATo. If the temperature difference is less than the set temperature difference, i.e., it is judged that a period of time for stopping the freezer is a long period of time, an engine 1 is stopped, a compressor 2 is stopped at a step 29 and at the same time motors 5 and 9 are stopped, a cooling operation is stopped and in turn if it is judged that the temperature difference is not less than the set temperature difference, i.e., a time for stopping the freezer is a short period of time, the engine 1 is operated in an idling operation and a compressor 2 is stopped at a step 31 and at the same time the motors 5 and 9 are stopped and a cooling operation is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a refrigeration system suitable for land transport refrigeration systems such as refrigerated cars.

(Prior Art) In conventional refrigeration systems of this type, the compressor is driven by an engine for driving the refrigeration system that is separate from the engine for driving the vehicle, and when the temperature inside the freezer rises to a predetermined temperature, this engine is automatically activated. The engine is started, and when the temperature inside the freezer drops to a predetermined temperature, the engine is automatically stopped to maintain the temperature inside the freezer within a certain range.

(Problems to be Solved by the Invention) In the above-mentioned conventional device, when the temperature outside the freezer is high and the amount of heat input into the freezer is large, the engine starts and stops frequently, and the engine There were problems such as depleting the spark needed to start the engine, shortening its lifespan, and accelerating the contamination of engine oil due to incomplete combustion when starting the engine.

(Means for Solving the Problems) The present invention has been proposed to solve the above problems, and its gist is that by starting and stopping an engine for driving a compressor, In a refrigeration system for adjusting the temperature of a refrigerator, there is provided a means for determining the length of time for which the operation of the refrigeration system should be stopped, and a means for determining the length of time for which the operation of the refrigeration system should be stopped; The refrigeration system is characterized in that it is provided with a control device having a determining means for determining idle operation of the engine when the time is reached.

(Function) In the present invention, the determination means determines the length of time for which the operation of the refrigeration system should be stopped, and the determination means determines to stop the engine if the determination result is a long time, and if the determination result is a short time. Determine engine idle operation.

(Embodiment) An embodiment of the present invention is shown in Figs. 1 and 2, in which Fig. 1 is a system diagram of a refrigeration system, and Fig. 2 is a flowchart.

In FIG. 1, 1 is an engine, 2 is a compressor driven by the engine 1, 3 is a condenser, and 4 is a fan for blowing outside air to the condenser 3, which is driven by a motor 5. 6 is an expansion valve, 7 is an evaporator disposed in the freezer 10, and 8 is a fan for blowing air inside the refrigerator to the evaporator 7, which is driven by a motor 9.

11 is a thermosensor that detects the temperature inside the freezer 10;
2 is a thermosensor that detects the temperature outside the freezer 10;
3 is a control device.

The high-temperature, high-pressure refrigerant gas discharged from the compressor 2 enters the condenser 3, where it exchanges heat with the outside air sent by the fan 4, condenses and liquefies, and becomes a low-temperature, high-pressure liquid refrigerant. This liquid refrigerant enters the expansion valve 6, where it is throttled and adiabatically expanded to become a gas-liquid two-phase gas and liquid at low temperature and low pressure. Next, this refrigerant enters the evaporator trough, where it evaporates and vaporizes by cooling the indoor air sent by the fan 8, becoming a low-temperature, low-pressure superheated refrigerant gas.

This refrigerant gas is then sucked into the compressor 2 and compressed again.

The internal temperature T3 detected by the thermosensor 11 is input to the comparison means 14 of the control device 13, where the setting means 1
It is compared with the set temperature T1 input from 5. The comparison result is output to the determining means 18, where if the internal temperature T1 is equal to or higher than the set upper limit temperature T1, the operation of the engine 1 is determined, and if the internal temperature T is equal to or lower than the set lower limit temperature T2, the operation of the engine 1 is determined. It is decided to stop engine 1.

Also, the temperature inside the refrigerator T detected by the thermosensor 11 and the temperature outside the refrigerator T detected by the thermosensor 12
0 is input to the determining means 16 of the control device 13. This discriminating means 16 consists of an arithmetic comparison means I6a and a setting means 16b. When the temperature inside the refrigerator Ti and the temperature outside the refrigerator T0 are inputted to the calculation comparison means 16a, the temperature difference T between the temperature outside the refrigerator T0 and the temperature inside the refrigerator Ti is calculated, and this temperature difference ΔT is set by the setting means 16a. Set temperature difference Δ input from 16b
It is compared with T0. Then, the temperature difference ΔT is the set temperature difference 6
When the temperature difference ΔT is 10 or more, it is determined that the time to stop the refrigeration system is short, and on the other hand, when the temperature difference ΔT is equal to or less than the set temperature difference Δ70, it is determined that the time to stop the refrigeration system is long.

Note that when the temperature difference ΔT is large, the amount of heat input from outside the refrigerator to the inside of the refrigerator increases, so the temperature rise rate inside the refrigerator is large. Therefore, the time for stopping the refrigeration device is sufficient.

The determination result of the determining means 1G is input to the determining means 18, where if the determination result is for a long time, it is decided to stop the engine 1, and when the determination result is for a short time, it is determined to idle the engine 1. The determined operating mode is output by the output means 19
The engine 1 and its rotational power are then output to a clutch 20 and a motor 5.9, which are interposed in a yarn path that transmits the rotational power to the compressor 2.

Since the clutch 20 is disengaged when the engine 1 is idling, the compressor 2 is stopped and the motor 5.
9 also stops. When a centrifugal clutch is used, the clutch is automatically disengaged when the engine 1 is idling.

A flowchart of the control device 13 is shown in FIG.

First, when the operation switch is turned on in step 21,
In step 22, the internal temperature T becomes the set upper limit temperature T.

It is determined whether or not this is the case, that is, whether or not a driving command has been issued. If it is silent, the engine 1 is started in step 23, and the compressor 2 is driven in step 24, and the motors 5 and 9 are started to perform cooling operation. On the other hand, if the determination in step 22 is negative, the process returns to step 22.

As the temperature inside the freezer 10 decreases due to the cooling operation, it is determined in step 25 whether the internal temperature T has become below the set lower limit temperature T1, that is, whether a stop command has been issued.

If not, the process returns to step 24 and the cooling operation is continued.

If so, in step 26, the internal temperature T and external temperature T6 are read. Next, in step 27, the temperature difference ΔT between the outside temperature T0 and the inside temperature T is reduced to the set temperature difference T.
It is determined whether or not it is less than or equal to 0.

If this is the case, that is, if it is determined that the time for stopping the refrigeration system is too long, the engine 1 is stopped in step 28, the compressor 2 is stopped in step 29, and the motors 5 and 9 are stopped. is stopped, the cooling operation is stopped, and the process returns to step 22.

On the other hand, if the determination in step 27 is negative, that is, if it is determined that the time to stop the refrigeration system is short, the engine 1 is idled in step 30, and the compressor 2 is activated in step 31. At the same time, the motors 5 and 9 are stopped, and the cooling operation is stopped. Next, in step 32, the temperature inside the refrigerator T and the temperature outside the refrigerator T0 are determined.
After reading 1. in step 33. Outside temperature T0 and inside temperature T.

It is determined whether the temperature difference ΔT between the two and the set temperature difference ΔT0T0 or more is greater than or equal to the set temperature difference ΔT0T0. If so, return to step 28 and start engine 1.
stops. Note that when the cooling operation is stopped, the temperature inside the refrigerator T increases due to heat intrusion from outside the refrigerator, and the temperature difference ΔT increases, but the temperature outside the refrigerator T0 decreases more than the increase in the temperature inside the refrigerator T, and the temperature Since the difference ΔT may decrease, step 3
The determination is made in step 3.

On the other hand, when the determination in step 33 is negative, it is determined in step 34 whether or not the internal temperature T is equal to or higher than the set upper limit temperature T1, that is, whether or not an operation command has been issued. If this is the case, the rotation speed of the engine l is increased in step 35, and the process moves to step 24, and cooling operation is performed.If it is determined that the cooling operation is not possible, the process moves to step 30, and the engine l rotation speed is increased.
continues to idle.

As described above, when the internal temperature T becomes equal to or higher than the set lower limit temperature T2 and the operation of the refrigeration system is stopped, the engine 1 is stopped when the determining means 16 determines that the time to be stopped is too long. , fuel waste is avoided.

On the other hand, when it is determined that the time during which the operation of the refrigeration system should be stopped is short, engine 1 is operated at idle without being stopped, so that frequent starting and stopping of engine 1 is eliminated, and engine 1 is started. Wear and tear of the starter is suppressed, and a reduction in its lifespan is prevented.

A second embodiment is shown in FIG.

In FIG. 3, the internal temperature T detected by the thermosensor 11 is input to the comparison means 42 of the control device 41,
Here, it is compared with the set temperature input from the setting means 43, and the comparison result is sent to the determining means 44.

The determining means 42 determines the operation of the refrigeration system when the internal temperature T, becomes equal to or higher than the set upper limit temperature T1, and sets the internal temperature T,
When the temperature exceeds the set lower limit temperature T2, it is decided to stop the refrigeration system. This determination is output via the output means 46, and when the refrigeration system is in operation, the engine 1 and motor 5.9 are started, and when the refrigeration system is stopped, the engine 1 and motor 5.9 are started.
9 is stopped.

Further, the comparison result of the comparison means 42 is inputted to the determination means 45. The determining means 45 includes a time integrating means 4λ, a comparing means 45b, a setting means 45c, and a storing means 45d. When the stop command signal is input from the comparing means 42, the time integrating means 45a starts integrating the time, and then the zero time integrating means 45a accumulates the stop time until the operation command signal is input. Time is comparison means 45b
, and is compared with the set time input from the setting means 45c.

When this stop time is longer than the set time, it is determined that the next stop time of the refrigeration equipment is long, and when the stop time is less than the set time, the next stop time of the refrigeration equipment is determined to be short. This determination result is output to the storage means 45d, and the storage means 45d temporarily stores this determination result, and when the next refrigeration equipment stop command is output from the comparison means 42 to the determination means 44, The above determination result is output to the determining means 44.

Thus, in the determining means 44, when the stop command signal for the refrigeration system is inputted from the comparison means 42, the determination result from the storage means 45 is inputted, and when the stoppage time according to this determination result is long, the engine If the stop time is short based on the above determination result, it is determined to idle the engine 1. This determination result is output to the engine 1 and motors 5 and 9 via the output means 46, thereby stopping the operation of the refrigeration system.

On the other hand, when the operating signal of the refrigeration system is inputted to the determining means 44 from the comparing means 42, the determining means 44 determines to start the engine 1 or to switch the engine 1 from idling operation to steady operation, and this determination result is The signal is output to the engine 1 and motors 5 and 9 via the output means 46, and cooling operation of the refrigeration system is started.

The other configurations and operations are the same as those of the first embodiment shown in FIG. 1, and corresponding members are given the same reference numerals and their explanations will be omitted.

(Effects of the Invention) In the present invention, the time at which the operation of the refrigeration system should be stopped is determined, and when the determination result is a long time, the engine is stopped to avoid wasting fuel.

When the determination result is a short time, the engine is idled without being stopped, so frequent starting and stopping of the engine is eliminated, and wear and tear on the starter and contamination of the engine oil can be suppressed.

[Brief explanation of the drawing]

1 and 2 show a first embodiment of the present invention, FIG. 1 is a system diagram of a refrigeration system, and FIG. 2 is a control flowchart. FIG. 3 is a system diagram of a refrigeration system according to a second embodiment of the present invention. Engine...-1, compressor-2, control? iD device-43, Figure 2

Claims (1)

[Claims] In a refrigeration system that adjusts the temperature inside a freezer by starting and stopping an engine for driving a compressor, there is a means for determining the length of time for which the operation of the refrigeration system should be stopped, and a determination result of this determination means. A refrigeration system comprising: a control device that determines to stop the engine when the determination result is a long time, and determines to idle the engine when the determination result is a short time.