JPS6151232B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cooling/refrigeration system for a refrigerated vehicle that is capable of cooling the inside of the freezer and cooling the driver's cabin at the same time.

[Conventional technology]

In recent years, as the installation of air-conditioning devices in automobiles has become commonplace, there has been an increasing demand for cooling the driver's cabin in refrigerated vehicles as well.

For this reason, conventionally, in Japanese Utility Model Application No. 51-7813, an evaporator for cooling the driver's cabin is connected in series downstream of the evaporator for freezing to obtain the freezing effect of the freezer and the cooling effect of the driver's cabin. A device has been proposed.

[Problem that the invention seeks to solve]

However, in the conventional device described above, a freezing evaporator is provided on the upstream side, a cooling evaporator is provided on the downstream side, and these evaporators are directly connected, making it difficult to achieve both freezing and cooling effects. It was hot.
In other words, if the evaporation pressure is set to obtain a relatively low evaporation temperature suitable for refrigeration, the evaporation pressure in the cooling evaporator will become too low, causing a problem of frosting in the cooling evaporator. . Therefore, if the expansion valve is designed so that a considerable amount of the refrigerant has finished evaporating at the outlet of the cooling evaporator, a large proportion of the refrigerant flowing into the cooling evaporator has already become gas refrigerant, so it is not noticeable in the cooling evaporator. There is a problem that only the cooling effect due to heat can be obtained, and the cooling capacity is very small, resulting in insufficient cooling.

In view of the above points, it is an object of the present invention to satisfactorily achieve both freezing and cooling effects.

[Means for solving problems]

In order to achieve the above object, the present invention includes: (a) a cooling evaporator that cools the inside of a driver's cabin; (b) a cooling blower that blows air to the cooling evaporator; and (c) a (d) an evaporation pressure adjustment valve connected in series to the outlet side to adjust the evaporation pressure of the refrigerant, and (d) a refrigeration evaporator connected in series to the outlet side of the evaporation pressure adjustment valve to cool the inside of a freezer that stores objects to be frozen. (e) A refrigeration blower for blowing air to the refrigeration evaporator; (f) A refrigeration blower installed at least on the inlet side of the refrigeration evaporator to adjust superheat of the refrigerant at the outlet of the refrigeration evaporator. (g) a compressor and condenser forming a refrigeration cycle together with the cooling/refrigeration evaporator, evaporation pressure adjustment valve, and automatic expansion valve; Adopt the technical means of providing a vessel.

[Effect]

According to the above technical means, by the action of the evaporation pressure regulating valve, the evaporation pressure in the upstream cooling evaporator is set to a relatively high pressure suitable for cooling action, while the downstream cooling evaporator The evaporation pressure in the vessel can be set to a low pressure suitable for refrigeration. Therefore, refrigerant evaporation temperatures suitable for cooling and freezing can be independently obtained in the cooling evaporator and freezing evaporator, respectively.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a system diagram of a refrigeration cycle of an embodiment of the device of the present invention, where 1 is a compressor that compresses refrigerant, and the gaseous refrigerant that has become high temperature and high pressure by this compressor 1 is sent to a condenser 2. In the condenser 2, heat is radiated to the air sent from the condenser blower 2a, and the air is liquefied. Further, the refrigerant liquefied by the condenser 2 is sent to the receiver 3, where the gaseous refrigerant that has not yet been liquefied is separated. A dryer 4 is disposed on the outlet side of the receiver 3 and is used to remove moisture mixed into the refrigerant. The liquid refrigerant from which water has been removed in the dryer 4 expands adiabatically when passing through the automatic expansion valve 5, and becomes low temperature.
The pressure becomes low and is sent to the cooling evaporator 6 located in the driver's cab of the refrigerated vehicle.

The refrigerant then exchanges heat with the air sent from the cooling blower 7 in the cooling evaporator 6, removes the heat of vaporization for the liquid refrigerant from the air, and has a pressure determined by the evaporation pressure regulating valve 8. The air is evaporated under the first evaporation pressure (for example, 1.9 Kg/cm ² G), and at this time, the heat of vaporization due to evaporation of the refrigerant is removed and the air is cooled by the cooling blower 7 driven by the electric motor. The air conditioner is sent to the driver's cabin to cool the inside of the driver's cabin.

The refrigerant that has undergone heat exchange in the cooling evaporator 6 is sent to the evaporation pressure regulating valve 8, where it is adiabatically expanded again and the evaporation pressure is changed to a second evaporation pressure lower than the first evaporation pressure (for example, 0.5 kg/cm ² G) and then sent into the freezing evaporator 9.

The refrigerant sent to the refrigeration evaporator 9 exchanges heat again with the air in the freezer (not shown) sent from the refrigeration blower 10 driven by an electric motor, and is left behind in the cooling evaporator 6 from the air. The liquid refrigerant takes away the heat of vaporization for evaporation, and evaporates under the second evaporation pressure adiabatically expanded by the evaporation pressure regulating valve 8. At this time, the air that has been cooled by being deprived of the heat of vaporization due to the evaporation of the refrigerant is sent into the freezer by the freezing blower 10, thereby freezing the interior of the freezer.

Here, the cooling evaporator 6 and the freezing evaporator 9
The flow rate of the liquid refrigerant sent to the temperature sensing cylinder 18, which will be described later, is
is automatically adjusted by the automatic expansion valve 5 provided at the outlet of the freezing evaporator 9 so that the superheat amount of the freezing evaporator 9 becomes the superheat amount set in the automatic expansion valve 5. If the cooling evaporator 6 and the freezing evaporator 9 are controlled to cool down, for example, and the heat load on the cooling evaporator 6 and the freezing evaporator 9 is reduced, the throttle amount of the automatic expansion valve 5 will gradually increase to reduce the amount of liquid refrigerant. At that time, the cooling evaporator 6
If the evaporation pressure of the cooling evaporator 6 attempts to drop below the set pressure of the evaporation pressure adjustment valve 8, the throttling amount of the evaporation pressure adjustment valve 8 increases to maintain the evaporation pressure of the cooling evaporator 6 at the set value of the evaporation pressure adjustment valve 8. On the other hand, the evaporation pressure of the refrigeration evaporator 9 decreases as the throttling amount of the evaporation pressure adjustment valve 8 increases, and becomes an evaporation pressure commensurate with the air temperature in the freezer where the refrigeration evaporator 9 is stored. ,
All of the liquid refrigerant sent by the automatic expansion valve 5 is evaporated in the refrigeration evaporator 9.

The refrigerant completely vaporized in the refrigeration evaporator 9 is sent to the compressor 1 again to complete the refrigeration cycle.

Reference numeral 11 denotes a defrosting passage, which leads the high-temperature, high-pressure refrigerant discharged from the compressor 1 directly to the freezing evaporator 9 to melt the frost attached to the freezing evaporator 9.
12 is installed in this defrosting passage 11, and the defrosting passage 1
The defrosting valve is a defrosting valve that opens and closes 1, and is made of, for example, a solenoid valve. 13 is an accumulator installed between the refrigeration evaporator 9 and the compressor 1 in the refrigeration cycle, which compresses the refrigerant that has been cooled and liquefied in the refrigeration evaporator 9 while remaining in liquid form, mainly during defrosting. This prevents it from being introduced into the machine 1.

Reference numeral 14 denotes a bypass passage that directly introduces the liquid refrigerant from which water has been removed in the dryer 4 into the freezing evaporator 9 by bypassing the automatic expansion valve 5, the cooling evaporator 6, and the evaporation pressure regulating valve 8. , used when cooling the driver's cabin is not required. Reference numerals 15 and 16 indicate first and second on-off valves (for example, electromagnetic valves) that serve as switching means for switching the flow of refrigerant to either the bypass passage 14 or the cooling evaporator 6; It is installed on the inlet side of the automatic expansion valve 5 of the cycle. Reference numeral 17 denotes an automatic expansion valve disposed on the exit side of the first on-off valve 15 of the bypass passage 14, which adiabatically expands the liquid refrigerant passing through the bypass passage 14. 18,1
Reference numerals 9 denote temperature-sensitive cylinders of the automatic expansion valves 5 and 17, respectively, which are installed at the outlet of the refrigeration evaporator 9.

Here, the automatic expansion valve 5 is used to adjust the superheat of the refrigerant at the outlet of the refrigeration evaporator 9 as described above, so it introduces the refrigerant pressure at the outlet of the refrigeration evaporator 9, and adjusts the introduced pressure and the Hot cylinder 18
This is a so-called external equalization type expansion valve that controls the valve opening depending on the internal pressure.

Next, the electric circuit of the cooling/refrigeration system for a refrigerated vehicle having the above structure will be explained based on FIG. 2.

In FIG. 2, reference numeral 20 denotes a DC power source such as an on-board battery, and one terminal (for example, a negative terminal) is grounded to the vehicle body side. 21 is fuse, 22
is a frozen switch. Reference numeral 23 denotes a freezing thermostat, which is disposed inside the freezer and is energized only when the temperature inside the freezer is above a set temperature.
Reference numeral 24 denotes a refrigeration relay, which includes an excitation coil 24a and normally open contacts 24b and 24c that close only when the excitation coil 24a is excited. 25 is a defrosting switch, and 26 is a rectifier. 1a is compressor 1
This is a magnetic clutch that connects and disconnects the transmission of driving force from, for example, an engine for driving a refrigerated vehicle. 27
29 is a cooling switch, and 29 is a cooling thermostat installed near the outlet of the cooling evaporator 6, which is energized only when the temperature in the operating room is above a set temperature. 28 is a cooling relay, which includes an excitation coil 28a, a normally open contact 28b that closes only when the excitation coil 28a is excited, and an excitation coil 28a.
It consists of a normally closed contact 28c that opens only when energized.

Next, the operation of the cooling/refrigeration system having the above configuration will be explained. The apparatus constructed as described above can be operated in three ways: cooling/freezing operation, freezing operation, and cooling operation, by opening and closing the on-off valves 15 and 16, which constitute switching means.

First, when only freezing is performed in the freezer, the air conditioner switch 27 is left turned off, and only the freezing switch 22 is turned on.

At this time, the refrigeration thermostat 23 senses the temperature inside the freezer, and if the temperature is higher than the set temperature (for example -10°C), the voltage from the power supply 20 is switched to the refrigeration relay 24.
The excitation coil 24a is excited to close the normally open contacts 24b and 24c. When the normally open contact 24c closes, the voltage from the power supply is applied to the defrosting switch 25, and when defrosting is not required and the defrosting switch 25 closes the refrigeration blower 10 side, the refrigeration blower 1
0, and the refrigerating blower 10 starts rotating. Furthermore, when the normally open contact 24b closes, a current flows through the magnetic clutch 1a that transmits the driving force to the condenser blower 2a and the compressor 1.
a and compressor 1 are started to operate.

In addition, the voltage from the power supply 20 is applied to the cooling relay 28.
It is transmitted to the normally closed contact 28c of the air conditioner switch 2.
7 is turned off, the excitation coil 28a is not excited, so current flows to the first on-off valve 15 via this normally closed contact 28c, and the first on-off valve becomes open.

In this state, only the first on-off valve 15 is open and the second on-off valve 16 is closed, so the refrigerant discharged from the compressor 1 passes through the condenser 2, receiver 3, and dryer 4, and then flows into the bypass passage 14 in its entirety. After being adiabatically expanded by the automatic expansion valve 17, it is introduced into the freezing evaporator 9, where it exchanges heat and cools the freezer.
After that, it returns to the compressor 1 again.

In this case, the refrigerant does not flow into the cooling evaporator 6 at all, so unnecessary refrigerant flows into the cooling evaporator 6 when there is no need to cool the driver's cabin, such as in winter, and even if the cooling evaporator 6 is It is possible to cool the inside of the driver's cabin by exchanging heat even if the amount of heat is reduced, thereby preventing the occurrence of a situation that would cause discomfort to the occupants.

Additionally, the compressor 1 and condenser 2 are originally designed to have a capacity sufficient to allow sufficient heat exchange between the evaporators 6 and 9 for cooling and freezing. Since the refrigerant is directly introduced only into the freezing evaporator 9, the refrigeration capacity for cooling the inside of the freezer can be significantly increased, and rapid freezing inside the freezer becomes possible.

When the temperature inside the freezer falls from above the set temperature of the freezing thermostat 23 to the set temperature value, the freezing thermostat 23 is turned off and the first on-off valve 1 is turned off.
5 is closed, and the refrigeration blower 10, condenser blower 2a, and compressor 1 that have been operating until then stop operating.

Next, when cooling the driver's cabin and freezing the freezer at the same time, both the cooling switch 27 and freezing switch 22 are turned on.

At this time, the temperature inside the driver's compartment is set to a predetermined temperature (for example, 25
C), the cooling thermostat 29 closes, the excitation coil 28a of the cooling relay 28 is excited, the normally closed contact 28c opens, and the normally open contact 28b closes.

Therefore, in this state, current does not flow to the first on-off valve 15, but current flows to the second on-off valve 16, which closes the first on-off valve 15 and opens only the second on-off valve 16. The discharged refrigerant is liquefied in the condenser 2, then passes through the receiver 3 and dryer 4, and then flows to the automatic expansion valve 5, where it expands adiabatically, and then evaporates in the cooling evaporator 6. The first pressure is maintained at the set pressure by the evaporation pressure regulating valve 8.
A portion of the liquid refrigerant is evaporated by the evaporation pressure, and at this time, the heat of vaporization is removed from the air in the driver's cabin to cool the driver's cabin. Furthermore, after that, the wet vapor that has partially evaporated the liquid refrigerant in the cooling evaporator 6 is adiabatically expanded by the throttling action of the evaporation pressure regulating valve 8, and then in the freezing evaporator 9 at a second evaporation pressure lower than that of the cooling evaporator. All the remaining liquid refrigerant is evaporated, and at that time, the heat of vaporization is taken from the air inside the freezer to freeze the inside of the freezer, and then the compressor 1 is turned on again.
Return to

Simultaneous operation of cooling and freezing is sometimes performed as described above, but in that case, the evaporation pressure of the refrigerant in the cooling evaporator 6 is controlled by the evaporation pressure regulating valve 8 to the first evaporation pressure (for example, 2.1 Kg/ cm ² G, this is the refrigerant R
In the case of 12, the evaporation temperature is controlled to 0° C.), and a cooling temperature suitable for the cooling action is obtained, and frost formation in the evaporator 6 is prevented. On the other hand, the evaporation pressure in the refrigeration evaporator 9 is set to a second evaporation pressure (for example, 0.5 Kg/cm ² G, which is equal to the refrigerant R
In the case of 12, the evaporation temperature corresponds to -20°C), and a low cooling temperature suitable for refrigeration can be obtained.

Here, the function of the automatic expansion valve 5 will be specifically described based on FIG. A valve body 53 is disposed between the refrigerant outlet portion 52 communicating with the inlet side of the cooling evaporator 6, and the valve opening degree of the valve body 53 changes in response to the displacement of the diaphragm 55 via a pin 54. and thereby adjust the refrigerant flow rate. The gas pressure Pf in the thermosensor tube 18 that senses the refrigerant temperature on the outlet side of the refrigeration evaporator 9 is applied to the chamber 56 above the diaphragm 55, while the chamber 57 below the diaphragm 55 is
The outlet refrigerant pressure Pe of the refrigeration evaporator 9 is applied via the pressure take-off pipe 58, and the coil spring 59
A pressing force Ps is applied to the lower surface of the diaphragm 55. Therefore, when the operation of the refrigeration cycle is stable, the diaphragm 55 and the valve body 53 move to a position where the relationship Pf=Pe+Ps holds.
The valve body 53 remains stationary at the opening degree at that time, keeping the refrigerant flow rate constant.

By the way, since the superheat (degree of superheating) of the refrigerant at the outlet of the freezing evaporator 9 is determined by the refrigerant temperature and refrigerant pressure, the expansion valve is opened according to the pressure Pf and the refrigerant pressure Pe at the evaporator outlet. By controlling the temperature, the automatic expansion valve 5 can control the superheat of the refrigerant at the outlet of the freezing evaporator 9 to a predetermined value, and the cooling capacity of the freezing evaporator 9 can be effectively exhibited.

At this time, if only the room temperature in the driver's cabin falls below the predetermined temperature and the temperature inside the freezer is still above the predetermined temperature, the cooling thermostat 29
is turned off, the power supply to the second on-off valve 16 is stopped, and the second on-off valve 16 is turned off.
The on-off valve 16 will be closed, but the excitation coil 28 of the cooling relay 28 will also no longer be energized.
The normally closed contact 28c closes and the first on-off valve 15
energization is started, and the first on-off valve 15 is opened. Therefore, in this case, the cooling in the driver's cabin is stopped, the bypass passage 14 is opened, and only the freezing in the freezer can be effectively performed. Conversely, if only the temperature inside the freezer falls below the predetermined temperature and the inside of the operating room is still above the predetermined temperature, the refrigeration thermostat 23 is turned off, the operation of the refrigeration blower 10 is stopped, and the forced heat exchange inside the freezer is started. make it stop.

In addition, even if the temperature in either the operator's compartment or the freezer falls below the set temperature and one of the thermostats 23, 29 is turned off, the other thermostat 23, 29 will not turn on. If so, current will flow through the magnetic clutch 1a and the condenser blower 2a, so the compressor 1
There is no problem that the condenser blower 2a and the condenser blower 2a stop.

Further, when it becomes necessary to remove frost adhering to the vicinity of the freezing evaporator 9, the defrosting switch 25 senses the state and energizes the defrosting valve 12 to open the defrosting passage 11. At this time, the refrigerant does not flow to the condenser 2 side because various flow path resistances such as automatic expansion valves 5 and 17 are provided on the condenser 2 side, and almost the entire amount flows into the defrosting passage 11. It is directly introduced into the freezing evaporator 9, and the freezing evaporator 9 is defrosted. Note that at this time, the refrigeration blower 10 is stopped, so even if the high-temperature, high-pressure refrigerant discharged from the compressor 1 flows into the refrigeration evaporator 9, the temperature inside the freezer does not rise immediately.

Next, if only the driver's cabin is to be cooled, only the cooling switch 27 is turned on and the freezing switch 22 is turned off.

Even in this case, the excitation coil 2 of the cooling relay 28
If 8a is energized and the normally open contact 28b is closed,
Condenser blower 2a and magnetic clutch 1
A is energized, and the condenser blower 2a and the compressor 1 are operating, but the operation of the refrigeration blower 10 is stopped.

Therefore, in this state, heat exchange in the freezing evaporator 9 is suppressed, and conversely, the amount of heat exchange in the cooling evaporator 6 increases.

When the temperature in the operating room falls below a predetermined temperature, the cooling thermostat 29 is turned off and the operation of the compressor 1 and condenser blower 2a is stopped. However, since the cooling evaporator 6 remains cold for a while, the cooling blower 7 is made to continue operating even if the cooling thermostat 29 is turned off.

When both the air conditioning of the driver's cabin and the freezing of the freezer are not needed, it is sufficient to turn off both the air conditioner switch 27 and the freezing switch 22. However, in the device configured as described above, the rectifier 26 is connected during the electrical wiring to the condenser blower 2a. Since the condenser blower 2a continues to rotate by inertia after the switches 27 and 22 are turned off, even if the drive motor of the condenser blower 2a works as a generator, the electromotive force is generated by the rectifier 26. Due to the action, the magnetic clutch 1a
There is no possibility that the force will be transmitted to the side, and therefore, the disconnection of the magnetic clutch 1a will not be impaired.

In the above embodiment, the bypass passage 14 was branched on the inlet side of the automatic expansion valve 5 of the refrigeration cycle, but as shown in FIG. Even so, the above-mentioned operating effect can be obtained. Furthermore, in the embodiment shown in FIG. 3, there is no need to install a separate automatic expansion valve 17 in the bypass passage 14.
Therefore, one automatic expansion valve 5 can handle adiabatic expansion of the refrigerant in both the cooling evaporator 6 and the freezing evaporator 9, which also has the excellent effect of significantly reducing costs. become.

Furthermore, in the embodiment described above, two valves, the first and second on-off valves 15 and 16, were used as switching means for switching the flow of refrigerant to either the bypass passage 14 or the cooling evaporator 6; It goes without saying that the same effect can be obtained by disposing a three-way valve at the branch point of the bypass passage 14.

Moreover, in the embodiment described above, the bypass passage 1
Even if 4 is abolished, the first and second on-off valves 1
Even if 5, 16 and the automatic expansion valve 17 are also eliminated, it is possible to cool the driver's cabin of the refrigerated vehicle and freeze the freezer. At this time, cooling and freezing are controlled exclusively by starting and stopping the operation of the cooling and freezing blowers 7 and 10. The electric circuit in this case is wired as shown in Fig. 4, and the cooling fan 7 starts operating only when the cooling switch 27 and thermostat 29 are closed, and the refrigeration fan 10 starts operating only when the cooling switch 27 and thermostat 29 are closed. 22 and thermostat 23 are closed, and the condenser blower 2a and magnetic clutch 1a are set to start operating only when either cooling or freezing switches 27, 22 and thermostats 29, 23 are closed. Start driving. Also in this case, the temperature-sensitive cylinder 18 of the automatic expansion valve 5 installed on the inlet side of the cooling evaporator 6 is installed on the outlet side of the freezing evaporator 9.

In this case, if refrigeration is performed even when cooling is not required, a very small amount of cold air will flow into the driver's cab, but this is because the air conditioner in the driver's cab is a mixture of cold and warm air. This problem does not occur in refrigerated trucks that use

〔Effect of the invention〕

As explained above, according to the present invention, the refrigeration evaporator 9 is connected in series downstream of the cooling evaporator 6 via the evaporation pressure regulating valve 8, and an automatic Since the superheat of the refrigerant at the outlet of the freezing evaporator 9 is adjusted by the expansion valve 5, the cooling temperature in the cooling evaporator 6 and the cooling temperature in the freezing evaporator 9 can be adjusted to the cooling effect and the freezing effect, respectively. Suitable individual temperatures can be set, and the evaporation pressure adjustment valve 8
By this action, frost formation on the cooling evaporator 6 can be reliably prevented.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a refrigeration cycle that constitutes one embodiment of the device of the present invention, Fig. 2 is an electrical wiring diagram of the device illustrated in Fig. 1, and Fig. 3 is a diagram of a refrigeration cycle that constitutes another embodiment of the device of the present invention. The system diagram, FIG. 4 is an electrical wiring diagram of another embodiment of the device of the present invention, and FIG. 5 is a schematic configuration diagram for explaining the operation of the automatic expansion valve 5 of the device of the present invention. 1... Compressor, 2... Condenser, 5... Automatic expansion valve, 6... Cooling evaporator, 7... Cooling blower,
8...Evaporation pressure adjustment valve, 9...Refrigerating evaporator, 1
0... Refrigeration blower, 14... Bypass passage, 1
5, 16... An on-off valve serving as a switching means, 18,
19...Temperature cylinder.

Claims (1)

[Scope of Claims] 1. (a) A cooling evaporator that cools the inside of the operating room; (b) A cooling blower that blows air to the cooling evaporator; (c) On the outlet side of the cooling evaporator. an evaporation pressure adjustment valve connected in series to adjust the evaporation pressure of the refrigerant; (d) a refrigeration evaporator connected in series to the outlet side of the evaporation pressure adjustment valve to cool the inside of a freezer storing objects to be frozen; ) A refrigeration blower that blows air to the refrigeration evaporator; (f) A temperature-sensitive cylinder installed at least on the inlet side of the refrigeration evaporator to adjust superheat of the refrigerant at the outlet of the refrigeration evaporator. (g) a compressor and a condenser that form a refrigeration cycle together with the cooling/refrigeration evaporator, evaporation pressure adjustment valve, and automatic expansion valve; A cooling/freezing device for a refrigerated vehicle, which is characterized by: