JP4427310B2 - Refrigeration apparatus and operation control method thereof - Google Patents

Description

  The present invention relates to a refrigeration apparatus capable of performing not only cold insulation (cooling) in a cold box but also heat insulation (heating) and an operation control method thereof, and is useful when applied to, for example, a vehicle refrigeration apparatus.

2. Description of the Related Art Conventionally, in a vehicle refrigeration apparatus that can not only keep cold (cool) in a cool box but also keep warm (heated), there are the following two methods for heating for keeping warm.
(1) Hot water heating method (2) Hot gas refrigerant heating method

The hot water heating system is a system in which cooling water of a vehicle engine (its temperature is around 90 ° C.) is introduced into the cold storage chamber and the inside of the cold storage chamber is heated by dissipating heat from the hot water (for example, patents). Reference 1).
In the hot gas refrigerant heating method, refrigerant discharged from a compressor (in a high-temperature and high-pressure gas-phase state, generally referred to as “hot gas”) is directly introduced into the evaporator, and from the hot gas in the evaporator. This is a method of heating the inside of the cool box by dissipating heat. This hot gas refrigerant heating method uses the heat held by the high-temperature and high-pressure gas refrigerant discharged from the compressor to heat the inside of the freezer, so that it is different from the heating method that uses the condensation heat of the gas refrigerant. It is also called a condensation heating cycle.

In such a non-condensation heating cycle, the refrigerant discharged from the compressor is depressurized to a temperature equal to or lower than the internal temperature saturation pressure, and the interior is heated with sensible heat in the overheated region. And the high-low pressure of the refrigerant | coolant discharged from a compressor is controlled by adjusting the refrigerant | coolant gas amount circulated through a heating cycle. That is, when the discharge pressure becomes higher than the set value and surplus refrigerant is generated, the discharge pressure adjustment valve is opened, and the refrigerant amount is adjusted by diverting the surplus refrigerant to the condenser and the receiver side and letting it escape. When the amount of refrigerant gas in the heating cycle is insufficient and the discharge pressure drops to a low pressure below the set value, for example, the low pressure relief valve is opened and the refrigerant is returned from the receiver during the heating cycle to recover the discharge pressure. Control is taking place.
JP-A-10-160321 (paragraph [0016] and FIG. 4)

The following problems have been pointed out in the above two heating methods.
On the other hand, in the hot water heating method, it is necessary to separately construct a pipe for introducing the cooling water into the cold storage, and the mounting of the refrigeration apparatus on the vehicle becomes complicated.

Further, in a normal non-condensed refrigerant heating cycle, a constant heating capacity is obtained by high pressure control by opening / closing operation of a discharge pressure adjusting valve provided between the compressor and the condenser and low pressure control by a constant pressure expansion valve. be able to.
In the conventional discharge pressure regulating valve, the refrigerant gas amount (hot gas amount) during the heating cycle is adjusted, that is, control is performed so as to suppress the high pressure while charging by diverting the surplus refrigerant to the condenser and the receiver. .

Here, the opening / closing control of the discharge pressure regulating valve will be specifically described with reference to FIG.
In this open / close control, the first set pressure P1 and the second set pressure P2 are determined in advance according to various conditions (P1 <P2), and the pressure (high pressure) at the compressor outlet reaches the second set pressure P2. When the pressure rises, it is determined that there is excess refrigerant, and the discharge pressure adjustment valve is opened (valve opening degree 100%). Then, when the refrigerant gas is charged to the condenser side through the discharge pressure regulating valve, the pressure at the compressor outlet decreases due to the decrease in the refrigerant gas amount, so the second hysteresis set pressure P2h (P2h <P2) When the pressure drops to the point, the discharge pressure adjustment valve is closed (valve opening 0%). That is, the discharge pressure regulating valve is provided with hysteresis by the second set pressure P2 and the second hysteresis set pressure Ph2, and is controlled to open and close in the counterclockwise direction as indicated by an arrow in FIG.

  In such conventional operation control, when the refrigeration apparatus starts the heating operation from the operation stop state (hereinafter referred to as “heating operation start time”), or when the operation is switched from the cooling operation to the heating operation ( Hereinafter, it is necessary to charge a relatively large amount of excess refrigerant to the capacitor side by opening the discharge pressure adjustment valve. For this reason, when the discharge pressure adjustment valve is opened at the time of starting the heating operation or switching to the heating operation, the surplus refrigerant is diverted to the condenser or the receiver having a large space capacity, so that a sudden pressure drop occurs. Therefore, the second hysteresis setting pressure P2h The discharge pressure adjusting valve closes in a short period of time. However, since a sufficient amount of excess refrigerant remains on the heating cycle side without being diverted, the discharge pressure of the compressor immediately rises to the second set pressure P2, and the discharge pressure adjustment valve is opened again. .

Similarly, for example, as shown in FIG. 7, after the discharge pressure regulating valve frequently opens and closes for a short time due to fluctuations in the discharge pressure (high pressure), the surplus refrigerant in the heating cycle disappears and the discharge pressure When it settles, the opening and closing is stable.
As described above, if the opening / closing operation of the discharge pressure regulating valve is frequently repeated, not only the durability becomes a problem, but also the opening / closing sound generated by the opening / closing operation is not preferable as operation noise. For this reason, in order to improve the merchantability of the refrigeration apparatus, it is desired to reduce frequent opening and closing of the discharge pressure regulating valve without impairing the heating performance of the refrigeration apparatus.

  The present invention has been made in view of the above circumstances, and an object thereof is a refrigeration apparatus capable of improving frequent opening and closing operations of a discharge pressure regulating valve at the time of heating operation start-up and at the time of heating operation switching. And an operation control method thereof.

In order to solve the above problems, the present invention employs the following means.
The refrigeration apparatus according to the present invention bypasses the condenser, the receiver and the expansion valve, and depressurizes the high-temperature and high-pressure refrigerant discharged from the compressor to a temperature equal to or lower than the internal temperature saturation pressure of the cold storage by the decompression means. By introducing into the evaporator, the evaporator heats the inside of the cool box and heats the inside of the cool box, thereby returning the refrigerant that has become a low-temperature and low-pressure gas phase state to the compressor by this heat release. A refrigeration apparatus that performs a refrigerant heating operation, a pressure detection unit that detects a high pressure of the compressor, and a discharge pressure adjustment that opens and closes during the non-condensing heating operation and performs a high pressure control by diverting excess refrigerant to the condenser side a valve, the operation when switching to the heating operation from start-up and the cooling operation of the heating operation from the operation stop state, a predetermined pressure drop when the detected value of the pressure detecting means detects the high voltage of a predetermined value And is characterized in that it comprises a, a surplus refrigerant flow acceleration control means for forcibly extending the opening time of the normal control for opening the discharge pressure regulating valve until the.

According to the refrigeration apparatus of the present invention, when the detected value of the pressure detecting means detects a high pressure that is equal to or higher than a predetermined value when the heating operation is started from the operation stop state and when the operation is switched from the cooling operation to the heating operation. In order to forcibly extend the open time during normal control that opens the discharge pressure adjustment valve until a predetermined pressure drop occurs, a surplus refrigerant distribution promotion control means is provided. When the operation is switched from the operation to the heating operation, the excess refrigerant can be forcibly diverted to the condenser side, and the high pressure of the compressor can be lowered efficiently.

  In the above-described refrigeration apparatus of the present invention, it is preferable that the surplus refrigerant distribution promotion control means provide a predetermined delay time for maintaining the open state when the discharge pressure regulating valve is switched from the open state to the closed state. Thus, it is possible to efficiently reduce the high pressure of the compressor by diverting the surplus refrigerant to the condenser side within the delay time.

  Further, in the above-described refrigeration apparatus of the present invention, the surplus refrigerant flow promotion control means is in a predetermined open state before closing the discharge pressure adjusting valve when the heating operation is started and when the operation is switched from the cooling operation. It is preferable to provide a maintenance time, whereby the excess refrigerant can be diverted to the condenser side within the open state maintenance time, and the high pressure of the compressor can be lowered efficiently.

The operation control method of the refrigeration apparatus according to the present invention is a high-temperature and high-pressure refrigerant discharged from a compressor, bypasses a condenser, a receiver, and an expansion valve, and the inside temperature of the cool box is saturated by a decompression unit. By reducing the pressure to below the pressure and introducing it into the evaporator, the evaporator releases heat into the cool box and heats the inside of the cool box, and the refrigerant that has become a low-temperature and low-pressure gas phase by this heat release is sent to the compressor. The operation control method of the refrigeration apparatus performing the non-condensed refrigerant heating operation to return to the open and close state, and opens and closes the discharge pressure adjustment valve according to the detected value of the pressure detecting means for detecting the high pressure of the compressor during the non-condensed heating operation , by diverting excess refrigerant to the condenser side performs high-voltage control, the operation when switching to the heating operation from startup and the cooling operation of the heating operation from the operation stop state, the detection value of the pressure detecting means Characterized in that to facilitate the diversion of excess refrigerant by forcibly extending the opening time of the normal control for opening the discharge pressure regulating valve until a predetermined pressure drop when detecting more high value is there.

According to such an operation control method of the refrigeration apparatus, during the non-condensing heating operation, the discharge pressure adjustment valve is opened and closed according to the detected value of the pressure detecting means for detecting the high pressure of the compressor, and the surplus refrigerant is diverted to the condenser side. The high pressure control is performed, and the predetermined pressure is detected when the detected value of the pressure detecting means detects a high pressure equal to or higher than a predetermined value when the operation is stopped to start the heating operation and when the operation is switched from the cooling operation to the heating operation. Opening the discharge pressure adjustment valve until it drops, forcibly extending the open time during normal control to promote the diversion of surplus refrigerant, so when starting the heating operation from the shutdown state and from the cooling operation to the heating operation At the time of operation switching, excess refrigerant can be diverted to the condenser side within the forcedly extended open time, and the high pressure of the compressor can be lowered efficiently.

According to the refrigeration apparatus and its operation control method of the present invention described above, the surplus refrigerant is forcibly diverted to the condenser side when starting the heating operation from the operation stop state and when switching the operation from the cooling operation to the heating operation. Since the high pressure of the compressor can be lowered sufficiently, the following effects can be obtained.
(1) The frequent opening and closing operation of the discharge pressure adjusting valve (for example, a solenoid valve) is prevented, and the reliability and durability of the discharge pressure adjusting valve are improved.
(2) Since the number of opening and closing of the discharge pressure adjusting valve (for example, a solenoid valve) is reduced, the generation of noise due to the opening and closing noise can be reduced.
(3) In the case of a method in which a predetermined delay time is provided before closing the discharge pressure regulating valve, a heating cycle that is likely to occur when the outside air is low in a fixed time stop method in which a predetermined open state maintenance time is provided. Gas shortage can be prevented.

  In this way, in addition to improving the reliability and durability of the discharge pressure regulating valve, it is possible to reduce the operating noise, so that there is a significant effect on the improvement of the commerciality of the refrigeration apparatus.

Hereinafter, an embodiment of a refrigeration apparatus and a control method thereof according to the present invention will be described with reference to the drawings.
<First Embodiment>
FIG. 1 shows a configuration diagram of a vehicular refrigeration apparatus as a refrigeration apparatus according to a first embodiment of the present invention. 2 is an explanatory diagram showing a cooling cycle of the refrigeration apparatus for vehicles, FIG. 3 is an explanatory diagram showing a heating (heating) cycle of the refrigeration apparatus for vehicles, and FIG. 4 is a discharge pressure adjustment in the refrigeration apparatus for vehicles. It is explanatory drawing which shows the opening / closing control of a valve.

  A vehicle refrigeration apparatus 1 shown in FIG. 1 is an apparatus that is mounted on a vehicle such as a truck and cools and heats a container (loading room). The vehicular refrigeration apparatus 1 includes two cold storages 3A and 3B, and can perform not only cold storage (cooling) but also heat retention (heating) in the cold storages 3A and 3B. The cool box 3A is disposed on the front side of the vehicle and is also referred to as a front chamber. The cool box 3B is disposed on the rear side of the vehicle and is also referred to as a rear chamber.

  As shown in FIG. 1, the vehicular refrigeration apparatus 1 includes a compressor 4, a condenser 5, a receiver 6, expansion valves 7A and 7B, evaporators 8A and 8B, and an accumulator 9. These devices are shown in FIG. The refrigerant circulation system of the closed circuit which implement | achieves the cooling (refrigeration) cycle using a refrigerant | coolant is comprised by connecting sequentially through the refrigerant | coolant piping L1 shown inside with a thick continuous line. Moreover, the control apparatus 10 is equipped in the vehicle refrigeration apparatus 1, and the control apparatus 10 has 10 A of control parts, the memory | storage part 10B, and the input part 10C.

The two evaporators 8A and 8B are connected in parallel in the system together with the expansion valves 7A and 7B. More specifically, the refrigerant pipe L1 is branched in parallel with the refrigerant pipe L1-1 and the refrigerant pipe L1-2 between the outlet side of the receiver 6 and the outlet sides of the evaporators 8A and 8B.
One refrigerant pipe L1-1 is provided with an expansion valve 7A and an evaporator 8A in order from the downstream side in the refrigerant flow direction, and an on-off valve SV1 (electromagnetic valve) is provided on the upstream side of the expansion valve 7A. . The on-off valve SV1 opens and closes the refrigerant flow path (refrigerant pipe L1-1), and intermittently introduces the refrigerant to the evaporator 8A.

The other refrigerant pipe L1-2 is provided with an expansion valve 7B and an evaporator 8B in order from the downstream side, and an on-off valve SV2 is provided on the upstream side of the expansion valve 7B. The on-off valve SV2 opens and closes the refrigerant flow path (refrigerant pipe L1-2), and intermittently introduces the refrigerant to the evaporator 8B.
In this case, the evaporator 8A is disposed on the cold storage (front chamber) 3A side, and the evaporator 8B is disposed on the cold storage (rear chamber) 3B side.

Further, a bypass pipe L2 indicated by a thin solid line in FIG. 1 is connected to the refrigerant pipe L1 so as to bypass the condenser 5, the receiver 6, and the expansion valves 7A and 7B described above. One end side (upstream side) of the bypass pipe L2 is connected to the discharge side of the compressor 4, while the other end side (downstream side) of the bypass pipe L2 is branched into two bypass pipes L2-1 and L2-2. One bypass pipe L2-1 is connected to the inlet side of the evaporator 8A, and the other bypass pipe L2-2 is connected to the inlet side of the evaporator 8B.
Further, one bypass pipe L2-1 is provided with an open / close valve SV3 (solenoid valve) that opens and closes the refrigerant flow path (bypass pipe L2-1) and intermittently introduces the refrigerant into the evaporator 8A. The pipe L2-2 is provided with an on-off valve SV4 (solenoid valve) that opens and closes the refrigerant flow path (bypass pipe L2-2) and intermittently introduces the refrigerant to the evaporator 8B.

Therefore, when the on-off valves SV3 and SV4 are opened during the heating operation, the high-temperature and high-pressure refrigerant (hot gas) discharged from the compressor 1 is discharged from the compressor 1 by the bypass pipe L2, and the condenser 5, the receiver 6, and the expansion valve. 7A and 7B can be bypassed and introduced into the evaporators 8A and 8B.
The bypass pipe L2 is provided with a constant pressure expansion valve 11 as a pressure reducing means. In the constant pressure expansion valve 11, during the heating operation, the high-temperature and high-pressure refrigerant discharged from the compressor 4 is in a gas phase state up to a temperature equal to or lower than the internal temperature saturation pressure of the cold storage chambers 3 </ b> A and 3 </ b> B placed in an overheated state. While maintaining the pressure, the pressure is reduced.

  That is, the compressor 4, the constant pressure expansion valve 11, and the evaporators 8A and 8B are sequentially connected via the refrigerant pipe L1 and the bypass pipe L2, so that heating by a non-condensing refrigerant, which is generally called hot gas, is performed. The refrigerant circulation system that realizes the cycle is configured.

The refrigerant pipe L1 is provided with a discharge pressure adjusting valve 12 as discharge pressure adjusting means. The discharge pressure adjusting valve 12 is provided between the high pressure side (discharge side) of the compressor 4 and the inlet side of the condenser 5, and the high pressure side of the compressor 4 (constant pressure expansion valve from the discharge side of the compressor 4). 11 and the discharge pressure adjustment valve 12), that is, the pressure of the refrigerant (hot gas) in a gas phase at high temperature and high pressure discharged from the compressor 4 is a second set pressure (hereinafter referred to as a predetermined pressure). This is a solenoid valve that opens when the pressure is higher than P2. The solenoid valve of the discharge pressure regulating valve 12 used here is preferably an energized closed (normally open) type that enables reduction of power consumption.
Note that one end side of the bypass pipe L2 is connected to the refrigerant pipe L1 through which the high-pressure side refrigerant discharged from the compressor 1 flows upstream of the discharge pressure regulating valve 12.

  Therefore, when the refrigerant pressure on the high pressure side of the compressor 4 is higher than the predetermined pressure P2 during the heating operation in which the refrigerant flows through the bypass pipe L2, the discharge pressure adjustment valve 12 is opened and a part of the high pressure side refrigerant is removed. As an excess refrigerant, the refrigerant is diverted to the refrigerant pipe L1. Since this surplus refrigerant is led to the capacitor 5 and the receiver 6 and charged (stored), the above-described refrigerant pressure on the high-pressure side can be lowered to a predetermined pressure P2 or less. Thus, the refrigerant pressure on the high pressure side of the compressor 4 is adjusted so as not to become too high.

  The receiver 6 and the low pressure side of the compressor 4 (between the outlet side of the evaporators 8A and 8B and the suction side of the accumulator 9 or the compressor 4) are connected by a refrigerant pipe L3 as a refrigerant flow path. The refrigerant pipe L3 is provided with a low-pressure relief valve 13 as an opening / closing means for opening and closing the refrigerant flow path (refrigerant pipe L3) and intermittently circulating the refrigerant, and an on-off valve SV5 (electromagnetic valve).

The low pressure relief valve 13 is connected to the high pressure side of the compressor 4 by a thin pipe L4, and the refrigerant pressure on the high pressure side obtained through the thin pipe L4 is from a first set pressure (hereinafter referred to as a predetermined pressure) P1. It is a valve that opens when it is low. Therefore, during the heating operation (at this time, the on-off valve SV5 is opened), when the refrigerant pressure on the high pressure side of the compressor 4 is lower than the predetermined pressure P1, the low pressure relief valve 13 opens and the receiver 6 When a part of the refrigerant held in the refrigerant is returned to the low pressure side of the compressor 4, the refrigerant is added to the refrigerant in the gas phase at a low temperature and low pressure returning from the evaporators 8 </ b> A and 8 </ b> B to the compressor 4. The refrigerant pressure can be made higher than the predetermined pressure P1.
At this time, the refrigerant held in the receiver 6 flows (returns) from the receiver 6 to the low pressure side due to the differential pressure between the refrigerant pressure of the receiver 6 and the refrigerant pressure on the low pressure side of the compressor 4. In this case, the refrigerant pressure of the receiver 6 is determined by the outside air temperature because the refrigerant is simply held in the receiver 6.

Further, a pressure sensor 16 is installed on the high pressure side of the compressor 4 as pressure detection means on the high pressure side, and the pressure detection value of the refrigerant on the high pressure side by the pressure sensor 16 is compared with a predetermined pressure P2. The opening / closing control of the discharge pressure adjusting valve 12 is performed.
Further, the flow of the refrigerant is restricted in one direction between the compressor 4 and the discharge pressure adjusting valve 12, between the receiver 6 and the on-off valves SV1 and SV2, and between the evaporators 8A and 8B and the accumulator 9. Check valves 14A, 14B, 14C, and 14D are respectively installed.
Moreover, temperature sensors 15A and 15B that detect temperatures (internal temperatures) in the cold storages 3A and 3B are installed in the cold storages 3A and 3B.

  The control unit 10A of the control device 10 is interposed between the compressor 4 and a discharge pressure regulating valve 12, a condenser fan FM2, an evaporator fan FM1F, FM1R, and an engine (not shown) serving as a drive source for the compressor 4. The compressor clutch MCL, the on-off valves SV1 to SV5, the temperature sensors 15A and 15B, and the pressure sensor 16 are connected to each other by signal lines indicated by dotted lines in FIG. ), The open / close control of the discharge pressure adjusting valve 12 and the open / close valves SV1 to SV5, the condenser fan based on the internal temperature detection signal (internal temperature detection value) and the internal temperature set value of each temperature sensor 15A, 15B Operation / stop control of the FM2 and evaporator fans FM1F and FM1R, and further, intermittent control of the compressor clutch MCL (operation / stop control of the compressor 4) ) Is performed.

The control unit 10A normally compares the pressure detection value of the pressure sensor 16 with the predetermined pressure P2 as described above, and opens the discharge pressure adjustment valve 12 if the pressure detection value is equal to or greater than the predetermined value P2.
However, in each operation mode to be described later, when the vehicle refrigeration apparatus 1 starts the heating operation from the operation stop state (hereinafter referred to as “heating operation start”), or the operation is switched from the cooling operation to the heating operation. When the operation is performed (hereinafter referred to as “heating operation switching”), the open pressure of the discharge pressure adjusting valve 12 is forcibly extended to positively divert excess refrigerant to the condenser 5 side, thereby maintaining a constant pressure expansion valve. The control which reduces the refrigerant | coolant amount which flows into the 11 side is implemented. In the following description, such control is referred to as “excess refrigerant distribution promotion control means”, and this excess refrigerant distribution promotion control means is incorporated in the control unit 10A as a control circuit, for example.

  The input unit 10C of the control device 10 is configured to select the internal temperature setting value of each of the cold storages 3A and 3B, the selection of the operation mode, and the heating / cooling time for each cooling storage 3A and 3B (refrigerant to the evaporators 8A and 8B) Used to enter information such as the introduction time). In the storage unit 10B of the control device 10, the internal temperature detection values of the temperature sensors 15A and 15B, the internal temperature setting values of the cold storage units 3A and 3B, and other information are stored.

Here, each operation mode of the vehicle refrigeration apparatus 1 will be described with reference to [Table 1].
In Table 1, the front chamber thermo “ON” indicates that in the cooling operation, the temperature detection value of the temperature sensor 15A is higher than the temperature setting value of the cold storage 3A, and the temperature of the cold storage 3A is determined. This means that the cooling operation is executed. In the case of the heating operation, it is determined that the detected temperature value of the temperature sensor 15A is lower than the set value of the temperature in the cool box 3A, and the heating operation of the cool box 3A is executed. It means to do. Similarly, in the case of the cooling operation, the rear chamber thermo “ON” determines that the temperature detection value of the temperature sensor 15B is higher than the temperature setting value of the cold storage 3B and performs the cooling operation of the cold storage 3B. In the case of the heating operation, it is determined that the temperature detection value of the temperature sensor 15B is lower than the temperature setting value of the cool box 3B, and the heating operation of the cool box 3B is executed. means.

  In addition, in the case of the cooling operation, the front chamber thermo “OFF” determines that the temperature detection value of the temperature sensor 15A is equal to or lower than the temperature setting value of the cold storage 3A and stops the cooling operation of the cold storage 3A. In the case of heating operation, it is determined that the temperature detection value of the temperature sensor 15A is equal to or higher than the temperature setting value of the cold storage 3A, and the heating operation of the cold storage 3A is performed. It means stopping (temperature control stop). Similarly, in the case of the cooling operation, the rear chamber thermometer “OFF” determines that the internal temperature detection value of the temperature sensor 15B is equal to or lower than the internal temperature setting value of the cold storage 3B, and performs the cooling operation of the cold storage 3B. It means to stop (temperature control stop), and in the case of heating operation, it is determined that the temperature detection value of the temperature sensor 15B is equal to or higher than the temperature setting value of the cool box 3B, and the heating operation of the cool box 3B. Is stopped (temperature control is stopped).

  The marks “◎” and “×” indicate “open” and “closed” for the discharge pressure adjusting valve 12 and the on-off valves SV1 to SV5, and “operation” for the condenser fan FM2 and the evaporator fans FM1F and FM1R. And “stop”, and the compressor clutch MCL means “connected” (operation of the compressor 4) and “disengagement” (stop of the compressor 4).

As shown in Table 1, in the vehicle refrigeration apparatus 1, the following operation modes (1) to (5) can be selected.
(1) Cooling operation mode for both the front and rear chambers (2) Heating operation mode for both the front and rear chambers (3) Cooling for the front chamber and heating for the rear chamber (4) Heating for the front chamber and cooling for the rear chamber (5 ) Defrost operation mode

Then, in the control device 10, when any of the operation modes (1) to (5) is selected, the following operation modes (A) to (L) are selectively executed.
(A) Front chamber cooling / rear chamber cooling alternate operation mode (alternate operation of (B) and (C))
(B) Cooling of the front chamber only (temperature control stopped for the rear chamber) (C) Cooling of the rear chamber only (temperature control stopped for the front chamber) Operation mode (D) Simultaneous heating mode of front chamber heating and rear chamber heating (E) Only the front chamber is heated (temperature control is stopped for the rear chamber) (F) Only the rear chamber is heated (temperature control is stopped for the front chamber) Operation mode (G) Front chamber cooling and rear chamber heating alternate operation mode ((B) and ( F) Alternate operation)
(H) Front chamber heating / rear chamber cooling alternate operation mode (alternate operation of (E) and (C))
(I) Defrost operation mode for front chamber only (J) Defrost operation mode for rear chamber only (K) Simultaneous defrost operation mode for front and rear chambers

  That is, when the operation mode (1) is selected, the operation modes (A), (B), (C) are selectively executed, and when the operation mode (2) is selected, the operation modes (D), (E ), (F) are selectively executed, and when the operation mode (3) is selected, the operation modes (G), (B), (F) are selectively executed, and the operation mode (4) is selected. When this occurs, the operation modes (H), (E), and (C) are selectively executed. When the operation mode (5) is selected, any one of the operation modes (I), (J), and (K) is further selected and executed. The details of the operation modes (A) to (K) are as follows.

  When the operation mode (1) is selected, the operation mode (A) is executed if the front chamber thermo and the rear chamber thermo are ON. In the operation mode (A), the operation mode (B) and the operation mode (C) are alternately operated. This alternate operation is performed at intervals of, for example, 2 minutes. Note that the simultaneous operation is not performed at this time, and the alternate operation is performed because, in the cooling operation, when the temperatures of the two chambers are different, the evaporation pressure of the refrigerant is also different.

  When the operation mode (1) is selected, the operation mode (B) is executed if the front chamber thermo is ON and the rear chamber thermo is OFF. The operation mode (A) is also executed in the above-described operation mode (A) and the operation mode (G) described later.

  In the operation mode (B), the following cooling operation is performed. That is, the on-off valves SV2, SV3, SV4, SV5 are closed, and the on-off valve SV1 and the discharge pressure adjusting valve 12 are opened. Further, the evaporator fans FM1F and FM1R and the condenser fan FM2 are operated, and the compressor clutch MCL is connected (the compressor 4 is operated).

  The high-temperature and high-pressure gas-phase refrigerant discharged from the compressor 4 flows through the discharge pressure regulating valve 12 and flows into the capacitor 5. The refrigerant flowing into the condenser 2 gives heat to the outside air, and condenses itself into a high-temperature and high-pressure liquid refrigerant. The liquid refrigerant flows through the receiver 6 and the on-off valve SV1, adiabatically expands in the process of flowing through the expansion valve 7A, becomes a low-temperature and low-pressure liquid refrigerant, and then flows into the evaporator 8A. The liquid refrigerant that has flowed into the evaporator 8A cools the air in the cool box 3A, and evaporates to become a low-temperature and low-pressure gas refrigerant (vapor-phase refrigerant). This low-temperature and low-pressure gas refrigerant flows out of the evaporator 8A, then flows through the accumulator 9, and is sucked into the compressor 4 and compressed. Thereafter, the above process is repeated.

  As shown in FIG. 2, for the Mollier diagram I representing the saturation line, the cooling cycle at this time is as indicated by II in the figure. That is, in the cooling cycle II, the refrigerant is compressed by the compressor 4 from the point a to the point b, the refrigerant is condensed by the condenser 5 from the point b to the point c, and the refrigerant is expanded by the expansion valve 7A from the point c to the point d ( Decompression), from point d to point a is the evaporation of the refrigerant in the evaporator 8A (cooling in the cool box).

  When the operation mode (1) is selected, the operation mode (C) is executed if the front chamber thermo is OFF and the rear chamber thermo is ON. The operation mode (B) is also executed in the above-described operation mode (A) and the operation mode (H) described later.

In the operation mode (C), the following cooling operation is performed in the same manner as in the operation mode (b). That is, the on-off valves SV1, SV3, SV4, SV5 are closed, and the on-off valve SV2 and the discharge pressure adjusting valve 12 are opened. Further, the evaporator fans FM1F and FM1R and the condenser fan FM2 are operated, and the compressor clutch MCL is connected (the compressor 4 is operated).
The refrigerant compressed by the compressor 4 becomes a high-temperature and high-pressure gas phase, is discharged from the compressor 4, flows through the discharge pressure adjustment valve 12, and flows into the capacitor 5. The refrigerant that has flowed into the condenser 2 gives heat to the air outside the box, and condenses itself to become a high-temperature and high-pressure liquid refrigerant (liquid phase refrigerant). This liquid refrigerant flows through the receiver 6 and the on-off valve SV2, adiabatically expands in the process of flowing through the expansion valve 7B, becomes a low-temperature and low-pressure liquid refrigerant, and then flows into the evaporator 8B. The liquid refrigerant that has flowed into the evaporator 8B cools the air in the cool box 3B, and evaporates to become a low-temperature and low-pressure gas refrigerant (vapor-phase refrigerant). This low-temperature and low-pressure gas refrigerant flows out of the evaporator 8B, then flows through the accumulator 9, and is sucked into the compressor 4 and compressed. Thereafter, the above process is repeated.

  When the operation mode (2) is selected, the operation mode (D) is executed if the front chamber thermo and the rear chamber thermo are ON.

  In the operation mode (D), the following non-condensed refrigerant heating operation is performed. That is, the on-off valves SV1, SV2 and the discharge pressure adjusting valve 12 are closed, and the on-off valves SV3, SV4, SV5 are opened. Further, the evaporator fans FM1F and FM1R are operated, and the compressor clutch MCL is connected (the compressor 4 is operated). The capacitor fan FM2 is stopped.

  The refrigerant compressed by the compressor 4 becomes a high-temperature and high-pressure gas phase and is discharged from the compressor 4. This high-temperature, high-pressure, gas-phase refrigerant closes the discharge pressure regulating valve 12 with its pressure lower than the predetermined pressure P2, and therefore does not flow into the capacitor 5, but flows entirely into the constant pressure expansion valve 11. . The refrigerant guided to the constant pressure expansion valve 11 is depressurized while maintaining a gas phase state below the interior temperature saturation pressure of the cold storage chambers 3A and 3B, and then flows through the on-off valves SV3 and SV4 to the evaporators 8A and 8B. be introduced. In the evaporators 8A and 8B, the introduced refrigerant in the gas phase state dissipates heat without condensing, and heats the air in the cold storages 3A and 3B. The radiated refrigerant becomes a low-temperature and low-pressure gas phase, flows out of the evaporators 8A and 8B, flows through the accumulator 9, and is sucked into the compressor 4 and compressed. Thereafter, the above process is repeated.

  Thus, the heating operation with the non-condensing refrigerant is performed. As shown in FIG. 3, with respect to the Mollier diagram I representing a saturation line and an isotherm, the heating cycle at this time is as shown in III. In the heating cycle III, the refrigerant is compressed by the compressor 4 from the point a to the point b, the refrigerant is depressurized by the constant pressure expansion valve 11 from the point b to the point c, and the refrigerant in the evaporators 8A and 8B is from the point c to the point a. Heat dissipation (heating in the cold storage).

When the refrigerant pressure on the high pressure side of the compressor 4 becomes higher than the predetermined pressure P2 during the non-condensed refrigerant heating operation, that is, when the refrigerant pressure detected by the pressure sensor 16 becomes higher than the predetermined pressure P2. The discharge pressure regulating valve 12 is opened, and a part of the high-pressure side refrigerant is diverted and introduced into the condenser 6. As a result, the high-pressure side refrigerant pressure is reduced to a predetermined pressure P2 or less. The refrigerant thus introduced into the capacitor 6 is held by the receiver 6.
Further, as shown in FIG. 6, the discharge pressure adjusting valve 12 is opened when the refrigerant pressure rises to a predetermined pressure P2, and is closed when the pressure drops to the second hysteresis setting pressure P2h. Is provided.

On the other hand, when the refrigerant pressure on the high pressure side of the compressor 4 becomes lower than the predetermined pressure P1 during the non-condensed refrigerant heating operation, the low pressure relief valve 13 is opened and one of the refrigerant held in the receiver 6 is opened. By returning the part to the low pressure side of the compressor 4, it is added to the refrigerant in the gas phase state at a low temperature and low pressure returning from the evaporators 8 </ b> A and 8 </ b> B to the compressor 4. Thereby, the refrigerant pressure on the high-pressure side can be increased to a predetermined pressure P1 or higher.
That is, as shown in FIG. 6, the low-pressure relief valve 13 starts to open when the refrigerant pressure drops to the predetermined pressure P1, and the valve opening increases as the refrigerant pressure further decreases. Note that the low-pressure relief valve 13 is provided with hysteresis so that the opening and closing characteristics do not match as shown in the figure, that is, when the low-pressure relief valve is closed, it is fully closed at the first hysteresis setting pressure P1h.

  Further, as shown in FIG. 6, the predetermined pressures P1 and P2 are set to be lower in P1 than in P2, and in consideration of hysteresis (P1h <P2h), the timing when the discharge pressure adjustment valve 12 is open The time when the low-pressure relief valve 13 is open is set so as not to overlap.

  In the heating operation using the non-condensed refrigerant as described above, the amount of throttle of the constant pressure expansion valve 11 and the system of the non-condensed refrigerant heating cycle including the compressor 4, the constant pressure expansion valve 11 and the evaporators 8A and 8B are circulated. The refrigerant pressure on the high pressure side of the compressor 4 (discharge pressure of the compressor 4) is determined by the circulation flow rate of the refrigerant. Accordingly, when the discharge flow rate adjustment valve 12 is opened and the amount of the refrigerant held in the receiver 6 is increased, the refrigerant pressure on the high-pressure side is lowered when the circulation flow rate of the refrigerant is lowered. Therefore, in order to suppress a decrease in the refrigerant pressure on the high-pressure side, when the refrigerant pressure on the high-pressure side becomes lower than the predetermined pressure P1, the low-pressure relief valve 13 is opened, and a part of the refrigerant held in the receiver 6 By returning to the system of the condensed refrigerant heating cycle and adding it to the refrigerant flowing through the system, the circulation flow rate of the refrigerant is increased.

The refrigerant pressure drop will be described in further detail. The constant pressure expansion valve 11 reduces the pressure of the refrigerant introduced into the evaporators 8A and 8B to a temperature equal to or lower than the internal temperature saturation pressure of the cold storages 3A and 3B. As the refrigerant pressure increases, the opening degree decreases (throttles), and conversely, the opening degree increases as the refrigerant pressure decreases. Therefore, even if the refrigerant pressure on the high pressure side decreases due to a decrease in the circulation flow rate of the refrigerant, the refrigerant pressure on the low pressure side of the compressor 4 does not decrease immediately due to the action of the constant pressure expansion valve 11, and the constant pressure expansion valve 11 Begins to decline after fully opening. For this reason, in order to suppress the decrease in the refrigerant pressure in the non-condensed refrigerant heating cycle as early as possible, it is very effective to replenish the refrigerant according to the decrease in the high-pressure side refrigerant pressure.
Therefore, the refrigerant pressure on the high pressure side communicated with the thin pipe L4 is monitored, and when the refrigerant pressure on the high pressure side becomes lower than the predetermined pressure P1 as described above, the low pressure relief valve 13 is opened and held by the receiver 6. A part of the refrigerant is returned. Note that the low-pressure relief valve 13 may open when the refrigerant pressure is low even during the cooling operation such as the operation mode (A), so that the refrigerant pipe L3 can be reliably closed during the cooling operation. An on-off valve SV5 is provided.

  When the operation mode (2) is selected, the operation mode (E) is executed if the front chamber thermo is ON and the rear chamber thermo is OFF.

  In the operation mode (E), the non-condensed refrigerant heating operation is performed only for the cool box 8A. That is, the on-off valves SV1, SV2, SV4 and the discharge pressure adjusting valve 12 are closed, and the on-off valves SV3, SV5 are opened. Further, the evaporator fans FM1F and FM1R are operated, and the compressor clutch MCL is connected (the compressor 4 is operated). The capacitor fan FM2 is stopped.

  The refrigerant compressed by the compressor 4 becomes a high-temperature and high-pressure gas phase and is discharged from the compressor 4. As long as the pressure of the high-temperature and high-pressure refrigerant is lower than the predetermined pressure P2, the discharge pressure regulating valve 12 does not open, so that it does not flow into the capacitor 5 and is stored in the cold storage 3A by the constant pressure expansion valve 11. After the pressure is reduced while maintaining the gas phase state up to the internal temperature saturation pressure or less, the gas is introduced into the evaporator 8A through the on-off valve SV3. In the evaporator 8A, the introduced refrigerant in the gas phase state dissipates heat without condensing, and heats the air in the cool box 3A. The radiated refrigerant becomes a low-temperature and low-pressure gas phase, flows out of the evaporator 8A, flows through the accumulator 9, and is sucked into the compressor 4 and compressed. Thereafter, the above process is repeated. Thus, the heating operation with the non-condensed refrigerant is performed without condensing the refrigerant (see FIG. 3).

  Also during the non-condensed refrigerant heating operation, when the refrigerant pressure on the high pressure side of the compressor 4 becomes higher than the predetermined pressure P2, the discharge pressure adjustment valve 12 is opened and a part of the refrigerant on the high pressure side is opened. Is introduced into the capacitor 6. As a result, the refrigerant pressure is reduced below the predetermined pressure P2. Note that the refrigerant introduced into the capacitor 6 is held by the receiver 6.

  Even in the non-condensed refrigerant heating operation, when the refrigerant pressure on the high pressure side of the compressor 4 becomes lower than the predetermined pressure P1, the low pressure relief valve 13 is opened and the refrigerant held in the receiver 6 is used. Is returned to the low-pressure side of the compressor 4 to be added to the refrigerant in the gas phase at a low temperature and low pressure returning from the evaporator 8A to the compressor 4. Thereby, the refrigerant pressure can be increased to a predetermined pressure P1 or higher.

  When the operation mode (2) is selected, the operation mode (F) is executed if the front chamber thermo is OFF and the rear chamber thermo is ON.

  In the operation mode (F), the non-condensed refrigerant heating operation is performed only on the cool box 8B. That is, the on-off valves SV1, SV2, SV3 and the discharge pressure adjusting valve 12 are closed, and the on-off valves SV4, SV5 are opened. Further, the evaporator fans FM1F and FM1R are operated, and the compressor clutch MCL is connected (the compressor 4 is operated). The capacitor fan FM2 is stopped.

  The refrigerant compressed by the compressor 4 becomes a high-temperature and high-pressure gas phase and is discharged from the compressor 4. As long as the pressure of the high-temperature and high-pressure refrigerant is lower than the predetermined pressure P2, the discharge pressure regulating valve 12 does not open, so that it does not flow into the capacitor 5 and is stored in the cool box 3B by the constant pressure expansion valve 11. After the pressure is reduced while maintaining the gas phase state to the internal temperature saturation pressure or lower, the gas is introduced into the evaporator 8B through the on-off valve SV4. In the evaporator 8B, the introduced refrigerant in the gas phase state dissipates heat without condensing, and heats the air in the cool box 3B. The radiated refrigerant becomes a low-temperature and low-pressure gas phase, flows out of the evaporator 8B, flows through the accumulator 9, and is sucked into the compressor 4 and compressed. Thereafter, the above process is repeated. Thus, the heating operation with the non-condensed refrigerant is performed without condensing the refrigerant (see FIG. 3).

  Also during the non-condensed refrigerant heating operation, when the refrigerant pressure on the high pressure side of the compressor 4 becomes higher than the predetermined pressure P2, the discharge pressure adjustment valve 12 is opened and a part of the refrigerant on the high pressure side is opened. Is introduced into the capacitor 6. As a result, the refrigerant pressure is reduced below the predetermined pressure P2. Note that the refrigerant introduced into the capacitor 6 is held by the receiver 6.

  Even in the non-condensed refrigerant heating operation, when the refrigerant pressure on the high pressure side of the compressor 4 becomes lower than the predetermined pressure P1, the low pressure relief valve 13 is opened and the refrigerant held in the receiver 6 is used. Is returned to the low-pressure side of the compressor 4 to be added to the refrigerant in the gas phase state at a low temperature and low pressure returning from the evaporator 8B to the compressor 4. Thereby, the refrigerant pressure can be increased to a predetermined pressure P1 or higher.

  Next, when the operation mode (3) is selected, if the front chamber thermo and the rear chamber thermo are ON, the operation mode (G) is executed. In the operation mode (G), the operation mode (B) and the operation mode (F) are alternately operated. This alternate operation is performed at intervals of, for example, 2 minutes.

  When the operation mode (3) is selected, the operation mode (B) is executed if the front chamber thermo is ON and the rear chamber thermo is OFF.

  When the operation mode (3) is selected, if the front chamber thermo is OFF and the rear chamber thermo is ON, the operation mode (F) is executed.

  Next, when the operation mode (4) is selected, the operation mode (H) is executed if the front chamber thermo and the rear chamber thermo are ON. In the operation mode (H), the operation mode (E) and the operation mode (C) are alternately operated. This alternate operation is performed at intervals of, for example, 2 minutes.

  When the operation mode (4) is selected, the operation mode (E) is executed if the front chamber thermo is ON and the rear chamber thermo is OFF.

  When the operation mode (4) is selected, the operation mode (E) is executed if the front chamber thermo is OFF and the rear chamber thermo is ON.

  Next, when the operation mode (5) is selected, if the operation mode (I) is further selected, the defrost operation is performed only on the cool box 3A (evaporator 8A) as follows.

  That is, the on-off valves SV1, SV2, SV4 and the discharge pressure adjusting valve 12 are closed, and the on-off valves SV3, SV5 are opened. Further, the evaporator fan FM1F is stopped, the evaporator fan FM1R and the condenser fan FM2 are operated, and the compressor clutch MCL is connected (the compressor 4 is operated). The refrigerant compressed by the compressor 4 becomes a high-temperature and high-pressure gas phase and is discharged from the compressor 4. As long as the pressure of the high-temperature and high-pressure refrigerant is lower than the predetermined pressure P2, the discharge pressure regulating valve 12 does not open, so that it does not flow into the capacitor 5 and is stored in the cold storage 3A by the constant pressure expansion valve 11. After the pressure is reduced while maintaining the gas phase state up to the internal temperature saturation pressure or less, the gas is introduced into the evaporator 8A through the on-off valve SV3. In the evaporator 8A, the cold storage 3A (evaporator 8A) is defrosted by the introduced gas-phase refrigerant. The low-temperature low-pressure gas-phase refrigerant flowing out of the evaporator 8A flows through the accumulator 9 and is then sucked into the compressor 4 and compressed. Thereafter, the above process is repeated.

  Thus, the defrost operation with the non-condensing refrigerant is performed. Although illustration is omitted, the cold storage 3A closes the on-off valve SV3 when the temperature detection value of a temperature sensor (a sensor for measuring the surface temperature of the evaporator coil, etc.) that determines the end of the defrost reaches the target temperature, and performs the defrost operation. Exit. As defrost operation, timer defrost or manual defrost for controlling the start and end of defrost operation by a timer or manually is also possible.

  Also during the defrost operation, when the refrigerant pressure on the high-pressure side of the compressor 4 becomes higher than the predetermined pressure P2, the discharge pressure adjusting valve 12 is opened, and a part of the refrigerant on the high-pressure side is stored in the condenser 6. To be introduced. As a result, the refrigerant pressure is reduced below the predetermined pressure P2. Note that the refrigerant introduced into the capacitor 6 is held by the receiver 6.

  Also during the defrosting operation, if the refrigerant pressure on the high pressure side of the compressor 4 becomes lower than the predetermined pressure P1, a part of the refrigerant held in the receiver 6 with the low pressure relief valve 13 opened. Is returned to the low-pressure side of the compressor 4 to be added to the refrigerant in the gas phase at a low temperature and low pressure returning from the evaporator 8A to the compressor 4. Thereby, the refrigerant pressure can be increased to a predetermined pressure P1 or higher.

  When the operation mode (5) is selected, if the operation mode (J) is further selected, the defrost operation is performed only for the cool box 3B (evaporator 8B) as follows.

  That is, the on-off valves SV1, SV2, SV3 and the discharge pressure adjusting valve 12 are closed, and the on-off valves SV4, SV5 are opened. Further, the evaporator fan FM1F and the condenser fan FM2 are operated, the evaporator fan FM1R is stopped, and the compressor clutch MCL is connected (the compressor 4 is operated). The refrigerant compressed by the compressor 4 becomes a high-temperature and high-pressure gas phase and is discharged from the compressor 4. As long as the pressure of the high-temperature and high-pressure refrigerant is lower than the predetermined pressure P2, the discharge pressure regulating valve 12 does not open, so that it does not flow into the capacitor 5 and is stored in the cold storage 3B by the constant pressure expansion valve 11. After the pressure is reduced while maintaining the gas phase state to the internal temperature saturation pressure or lower, the gas is introduced into the evaporator 8B through the on-off valve SV4. In the evaporator 8B, the cold storage 3B (evaporator 8B) is defrosted by the introduced refrigerant in the gas phase. The low-temperature and low-pressure gas-phase refrigerant flowing out of the evaporator 8B flows through the accumulator 9, and is then sucked into the compressor 4 and compressed. Thereafter, the above process is repeated.

  Thus, the defrosting operation with the non-condensed refrigerant is performed without condensing the refrigerant. Although illustration is omitted, in the cool box 3B, the defrosting operation is performed by closing the on-off valve SV4 when the temperature detection value of the temperature sensor (sensor for measuring the surface temperature of the evaporator coil, etc.) for determining the end of the defrost reaches the target temperature. Exit.

  Even during the defrost operation, when the refrigerant pressure on the high pressure side of the compressor 4 becomes higher than the predetermined pressure P2, the discharge pressure adjustment valve 12 is opened, and a part of the high pressure side refrigerant is discharged. It is introduced into the capacitor 6. As a result, the refrigerant pressure is reduced below the predetermined pressure P2. The refrigerant introduced into the capacitor 6 is held by the receiver 6.

  Also during the defrosting operation, if the refrigerant pressure on the high pressure side of the compressor 4 becomes lower than the predetermined pressure P1, a part of the refrigerant held in the receiver 6 with the low pressure relief valve 13 opened. Is returned to the low-pressure side of the compressor 4 to be added to the refrigerant in the gas-phase state at a low temperature and low pressure returning from the evaporator 8B to the compressor 4. Thereby, the refrigerant pressure can be increased to a predetermined pressure P1 or higher.

  When the operation mode (5) is selected and the operation mode (K) is further selected, the defrost operation is performed for both of the coolers 3A and 3B (evaporators 8A and 8B) as follows. Is called.

  That is, the on-off valves SV1, SV2 and the discharge pressure adjusting valve 12 are closed, and the on-off valves SV3, SV4, SV5 are opened. Further, the condenser fan FM2 is operated, the evaporator fans FM1F and FM1R are stopped, and the compressor clutch MCL is connected (the compressor 4 is operated). The refrigerant compressed by the compressor 4 becomes a high-temperature and high-pressure gas phase and is discharged from the compressor 4. As long as the pressure of the high-temperature and high-pressure refrigerant is lower than the predetermined pressure P2, the discharge pressure regulating valve 12 does not open, so that it does not flow into the condenser 5 and is kept in the cold storages 3A and 3B by the constant pressure expansion valve 11. After being decompressed while maintaining the gas phase state below the internal temperature saturation pressure, the gas is introduced into the evaporators 8A and 8B through the on-off valves SV3 and SV4. In the evaporators 8A and 8B, the cold storages 3A and 3B (evaporators 8A and 8B) are defrosted by the introduced gas-phase refrigerant. The low-temperature and low-pressure gas-phase refrigerant flowing out of the evaporators 8A and 8B flows through the accumulator 9 and is then sucked into the compressor 4 and compressed. Thereafter, the above process is repeated.

Thus, the defrosting operation with the non-condensed refrigerant is performed without condensing the refrigerant. When the temperature detection value of the temperature sensor (a sensor for measuring the surface temperature of the evaporator coil or the like) for determining the end of the defrost reaches the target temperature, the on-off valves SV3 and SV4 are closed to end the defrost operation.
Even during the defrost operation, when the refrigerant pressure on the high pressure side of the compressor 4 becomes higher than the predetermined pressure P2, the discharge pressure adjustment valve 12 is opened, and a part of the high pressure side refrigerant is discharged. It is introduced into the capacitor 6. As a result, the refrigerant pressure is reduced below the predetermined pressure P2. Note that the refrigerant introduced into the capacitor 6 is held by the receiver 6.

  Also during the defrosting operation, if the refrigerant pressure on the high pressure side of the compressor 4 becomes lower than the predetermined pressure P1, a part of the refrigerant held in the receiver 6 with the low pressure relief valve 13 opened. Is returned to the low pressure side of the compressor 4 to be added to the refrigerant in the gas phase state at low temperature and low pressure returning from the evaporators 8A and 8B to the compressor 4. Thereby, the refrigerant pressure can be increased to a predetermined pressure P1 or higher.

  When the front chamber thermo and the rear chamber thermo are turned off, the stop mode (L) is entered. In the stop mode (L), all the on-off valves SV1 to SV5 except the energized open discharge pressure regulating valve 12 are closed, the condenser fan FM2 is stopped, and the compressor clutch MCL is disconnected (the compressor 4 is stopped). ), Only the evaporator fans FM1F and FM1R are operated.

  As described above, in the vehicular refrigeration apparatus 1, the high-temperature and high-pressure refrigerant discharged from the compressor 4 bypasses the condenser 5, the receiver 6, and the expansion valves 7 </ b> A and 7 </ b> B, and is constant-pressure expansion. The valve 11 is depressurized to below the inside temperature saturation pressure of the cool box 3A, 3B and introduced into the evaporators 8A, 8B. In order to perform a non-condensed refrigerant heating operation for returning the refrigerant that has become a low-temperature and low-pressure gas-phase state by this heat radiation to the compressor 4, a pipe for introducing hot water (engine cooling water) as in the hot water heating system is used. There is no need for construction and there is no need to store the liquid refrigerant in the accumulator, and the inside of the cold storages 3A and 3B can be heated quickly and efficiently.

  The vehicle refrigeration apparatus 1 includes the low pressure relief valve 13 that opens and closes the refrigerant pipe L3 that connects the receiver 6 and the low pressure side of the compressor 4, and the high pressure side refrigerant pressure of the compressor 4 is a predetermined pressure. When the pressure is lower than P1, the low pressure relief valve 12 is opened and a part of the refrigerant held in the receiver 6 is returned to the low pressure side of the compressor 4 to return to the compressor 4 from the evaporators 8A and 8B. By adding to the refrigerant in the gas phase state, the refrigerant pressure on the high-pressure side is set to be higher than the predetermined pressure P1, so that the circulation amount of the refrigerant can be secured and the heating capacity can be kept high. The pressure adjusting means in this case is not necessarily limited to the low pressure relief valve 13 and may be configured to open and close a valve such as an electric valve or an electromagnetic valve based on the pressure detection value of the pressure sensor 16.

  The vehicular refrigeration apparatus 1 described above includes surplus refrigerant distribution promotion control means for forcibly increasing the opening time of the discharge pressure regulating valve 12 when the heating operation is started and when the heating operation is switched. For example, the surplus refrigerant flow promotion control means selects the operation mode (2) from the operation stop state and starts the heating operation of (D), or performs the cooling operation in (A) of the operation mode (1). This is performed when the heating operation is started by switching to (D) of the operation mode (2) from the existing state, and the discharge pressure adjustment valve 12 is normally opened when the pressure becomes higher than the predetermined pressure P2. It is different from open / close control.

At the time of starting the heating operation and switching the heating operation, the discharge pressure adjusting valve 12 is closed at the same time when the heating operation is started. However, since surplus refrigerant is generated in the heating cycle, the pressure sensor 16 detects a high pressure equal to or higher than the predetermined value P2, and the discharge pressure regulating valve 12 is immediately opened.
Therefore, for example, as shown in FIG. 4, when the discharge pressure adjusting valve 12 is switched from the open state to the closed state, a delay time td is provided as the surplus refrigerant distribution promotion control means.

FIG. 4 shows a case where the heating operation is switched, and the discharge pressure adjusting valve 12 is closed at a time T when switching from cooling to heating. Therefore, the discharge pressure P detected by the pressure sensor 16 as the volume of the refrigerant circulation path decreases is To rise. As a result, the discharge pressure adjustment valve 12 is opened at time T1 when the discharge pressure rises to the predetermined value P2. However, since the condenser 5 and the receiver 6 are added to the refrigerant circulation volume, the discharge pressure P increases rapidly. At time ta, the pressure suddenly decreases to Pa.
Since this pressure Pa is lower than the second hysteresis set pressure P2h and higher than the first set pressure P1 (see FIG. 6), in the normal (conventional) opening / closing control, the discharge pressure adjusting valve 12 is at time T2. Closes immediately. Note that the pressure change ΔP in the figure is a differential pressure between the pressure Pa until the heating cycle is settled and the predetermined pressure P2.

However, since the delay time td from the open state to the closed state is provided, the discharge pressure adjusting valve 12 is actually closed at time T3 after the delay time td has elapsed from time T2. For this reason, the discharge pressure adjusting valve 12 is actually opened at time t from time T1 to T3.
That is, this time t is
Since t = ta + td,
Compared to the normal control, the opening time of the discharge pressure adjusting valve 12 is extended by the delay time td, and surplus refrigerant can be diverted to the condenser 5 side within this extended time. In other words, by providing the delay time td, it is possible to increase the amount of surplus refrigerant that opens the discharge pressure adjustment valve 12 longer by the delay time td and leads it from the heating cycle to the condenser 5 side.
Note that the delay time td is a value that can be set as appropriate according to various conditions. For example, a time of about 5 seconds is set.

Accordingly, the opening / closing cycle of the discharge pressure adjusting valve 12 is lengthened by the delay time td, and the amount of surplus refrigerant per cycle charged to the capacitor 5 side increases with the extension of the opening time. The frequent opening and closing of the discharge pressure regulating valve 12 that has occurred until the pressure becomes stable is eliminated or greatly reduced. Note that the number of opening and closing of the discharge pressure adjustment valve 12 required until reaching a stable heating cycle operation varies depending on the surplus refrigerant amount.
Further, since the charge of the surplus refrigerant is faster as the outside air temperature is lower, the surplus refrigerant is provided by setting the predetermined delay time td as described above and opening / closing the discharge pressure adjusting valve 12 (three times in the illustrated example). The surplus refrigerant flow promotion control means that can adjust the charge amount is also advantageous for preventing the phenomenon that the charge amount becomes too large and the refrigerant amount on the heating cycle side becomes insufficient.

<Second Embodiment>
Next, another embodiment of the above-described surplus refrigerant flow promotion control unit will be described with reference to FIG.
In this case, the surplus refrigerant distribution promotion control means has a predetermined open state maintaining time th that is set before the discharge pressure adjusting valve 12 is closed when the heating operation is started and when the heating operation is switched. This open state maintaining time th is, for example, when the cooling operation is switched to the heating operation, and in normal (conventional) control, the discharge pressure adjusting valve 12 is closed simultaneously with the operation switching, whereas only the predetermined open state maintaining time th. This time is set to delay the switching time from the open state to the closed state. The open state maintaining time th is a value appropriately determined according to various conditions, but is normally set to about 30 seconds.

That is, when the cooling operation is switched to the heating operation at time T, the discharge pressure adjusting valve 12 is maintained in the open state until the time T1 when the open state maintaining time th has elapsed from the time T, and the capacitor 5 is started from the heating cycle. The charging time is ensured by diverting excess refrigerant to the side. In other words, when the heating operation is started and when the heating operation is switched, the open state is maintained for a predetermined time th before the discharge pressure adjustment valve 12 is closed, and the surplus refrigerant is forcibly diverted to the condenser 5 side during this time. Let me charge it.
As a result, the surplus refrigerant on the heating cycle side is considerably reduced. Therefore, even if the opening / closing control of the discharge pressure regulating valve 12 is performed normally from the time T1, that is, from the time T1, the predetermined pressure P2 and the second pressure are controlled. Even when the opening / closing control is performed by detecting the hysteresis set pressure P2h, since the surplus refrigerant amount has already decreased considerably, the frequent opening / closing of the discharge pressure regulating valve 12 that occurs until the heating cycle operation becomes stable is prevented. Significantly reduced or eliminated.

  In the above-described refrigeration apparatus and its control method, the delay time td (first embodiment) and the open state maintenance time th (second state) are controlled for the opening / closing control of the discharge pressure regulating valve 12 at the time of starting the heating operation and switching the heating operation. The surplus refrigerant flow promotion control means as in the embodiment) is provided, and the opening time of the discharge pressure regulating valve 12 is positively extended as compared with that during normal control to force the surplus refrigerant on the heating cycle side to the condenser 5 side. Since the excess refrigerant is divided and charged to the capacitor 5 outside the heating cycle, the frequent opening and closing operation of the discharge pressure regulating valve 12 is improved. Accordingly, the valves such as the solenoid valve used as the discharge pressure adjusting valve 12 are increased in durability and reliability, and the operation noise of the refrigeration apparatus due to frequent opening and closing operations of the discharge pressure adjusting valve 12 is also reduced. The refrigeration apparatus has improved merchantability.

In the first and second embodiments described above, the refrigeration apparatus has been described as a vehicular refrigeration apparatus, but the present invention is not limited to this and can be applied to other refrigeration apparatuses.
In addition, as for the surplus refrigerant distribution promotion control means, the delay time td and the open state maintaining time th described above can be used together.
The configuration of the present invention is not limited to the above-described embodiment, and various modifications can be made to the configuration of the refrigeration cycle, for example, and can be changed as appropriate without departing from the scope of the present invention. it can.

It is a lineblock diagram of the refrigeration equipment for vehicles concerning a 1st embodiment of the present invention. It is explanatory drawing which shows the cooling cycle of the said refrigeration apparatus for vehicles. It is explanatory drawing which shows the heating cycle of the said refrigeration apparatus for vehicles. It is explanatory drawing which shows the delay time td as a surplus refrigerant | coolant flow distribution promotion control means in the said refrigeration apparatus for vehicles. It is explanatory drawing which shows the open state maintenance time th as 2nd Embodiment of the surplus refrigerant | coolant distribution | distribution promotion control part which concerns on this invention. . It is explanatory drawing which shows the normal (conventional) control of a discharge pressure regulating valve. It is explanatory drawing which shows the problem of the normal control shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle refrigeration apparatus 3A, 3B Cold storage 4 Compressor 5 Condenser 6 Receiver 7A, 7B Expansion valve 8A, 8B Evaporator 9 Accumulator 10 Control apparatus 10A Control part 10B Storage part 10C Input part 11 Constant pressure expansion valve 12 Discharge pressure adjustment valve 13 Low pressure relief valve 14A-14D Check valve 15A, 15B Temperature sensor 16 Pressure sensor L1 Refrigerant piping L2 Bypass piping L3 Refrigerant piping L4 Narrow piping L5 Bypass piping L6 Bypass piping SV1-SV5 Open / close valve (solenoid valve)
FM1F, FM1R Evaporator fan FM2 Condenser fan MCL Compressor clutch td Delay time (excess refrigerant flow promotion control means)
th open state maintenance time (excess refrigerant distribution promotion control means)

Claims (4)

By introducing the high-temperature and high-pressure refrigerant discharged from the compressor into the evaporator by bypassing the condenser, the receiver and the expansion valve, and reducing the pressure to a temperature equal to or lower than the internal temperature saturation pressure of the cold storage by the decompression means. A refrigerating apparatus that performs a non-condensed refrigerant heating operation in which the evaporator heat is radiated into the cool box and the inside of the cool box is heated, and the refrigerant that has become a low-temperature and low-pressure gas phase by the heat radiation is returned to the compressor. There,
Pressure detecting means for detecting the high pressure of the compressor;
A discharge pressure adjusting valve that opens and closes during the non-condensing heating operation, and distributes excess refrigerant to the condenser side to perform high pressure control;
The discharge pressure adjustment is performed until a predetermined pressure drop is detected when the detected value of the pressure detecting means detects a high pressure equal to or higher than a predetermined value at the time of starting the heating operation from the operation stop state and switching the operation from the cooling operation to the heating operation. Surplus refrigerant distribution promotion control means for forcibly extending the opening time during normal control to open the valve ;
A refrigeration apparatus comprising:   2. The refrigeration apparatus according to claim 1, wherein the surplus refrigerant flow promotion control means provides a predetermined delay time for maintaining the open state when the discharge pressure adjusting valve is switched from the open state to the closed state.   The surplus refrigerant flow promotion control means provides a predetermined open state maintaining time before closing the discharge pressure regulating valve when starting the heating operation and switching the operation from the cooling operation. The refrigeration apparatus according to 1. By introducing the high-temperature and high-pressure refrigerant discharged from the compressor into the evaporator by bypassing the condenser, the receiver and the expansion valve, and reducing the pressure to a temperature equal to or lower than the internal temperature saturation pressure of the cold storage by the decompression means. A refrigerating apparatus for performing a non-condensed refrigerant heating operation for radiating heat in the cool box by the evaporator and heating the cool box and returning the refrigerant that has become a low-temperature and low-pressure gas phase by the heat release to the compressor. An operation control method comprising:
During the non-condensing heating operation, the discharge pressure adjustment valve is opened and closed in accordance with the detection value of the pressure detection means for detecting the high pressure of the compressor, and the excess refrigerant is diverted to the condenser side to perform high pressure control and the operation is stopped. When the heating operation is started from the state and when the operation is switched from the cooling operation to the heating operation, the discharge pressure adjusting valve is set until a predetermined pressure drop is detected when the detected value of the pressure detecting means detects a high pressure of a predetermined value or more. An operation control method for a refrigeration apparatus, characterized by forcibly extending an open time at the time of normal control to promote and diverting a surplus refrigerant.

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