Temperature control system and its control method

Abstract

The present invention provides a temperature control system that can quickly start heating without causing a temporary drop in temperature. [Solution] The refrigerant circuit 3 of the vehicle air conditioning system 1 is equipped with a bypass channel 15 that guides the refrigerant discharged from the compressor 10 to the upstream or downstream of the evaporator 13, bypassing the condenser 11. The control unit has a hot gas heating mode in which a portion of the refrigerant flows through the bypass channel 15 and guides the hot water discharged from the condenser 11 to the heater core 18 using the compressor 10 as a heat source to heat the air, and a high-pressure refrigerant control mode in which the pressure of the refrigerant flowing through the condenser 11 is maintained at or above a predetermined value while the hot gas heating mode is in operation.

Description

Technical Field

[0001] The present disclosure relates to a temperature control system suitable for use in, for example, vehicle air conditioning and a control method thereof.

Background Art

[0002] Patent Document 1 discloses a vehicle air conditioner including a refrigerant circuit having a bypass flow path that bypasses a condenser.

[0003] The vehicle air conditioner of this document is disclosed to warm up and quickly start heating by recovering the heat of a battery or an electric heater with a chiller when starting heating at extremely low outside air temperatures (

[0382] and FIG. 34 of Patent Document 1).

[0004] Further, an assist reheat warm-up mode is disclosed in which the heating expansion valve is closed and refrigerant is not passed through the condenser, but is passed through the chiller via the bypass flow path (

[0390] and FIG. 35 of Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in Patent Document 1, heating cannot be quickly started when there is no auxiliary heat source such as a battery or an electric heater.

[0007] Furthermore, in Patent Document 1, since the indoor heat exchanger does not exchange heat with indoor air in each of the warm-up modes described above, when switching from the warm-up mode to the heating mode and starting heating with the indoor heat exchanger, the heat exchange between the refrigerant flowing through the indoor heat exchanger and the indoor air suddenly begins, causing a rapid drop in refrigerant pressure and a decrease in compressor power, which temporarily reduces heating capacity and results in a problem of slow heating startup.

[0008] This disclosure is made in view of these circumstances and aims to provide a temperature control system and a control method thereof that can suppress temporary temperature drops and quickly start heating. [Means for solving the problem]

[0009] A temperature control system according to one aspect of the present disclosure includes a refrigerant circuit having a compressor for compressing a refrigerant, a high-pressure heat exchanger for dissipating heat from the refrigerant compressed by the compressor, an expansion valve for expanding the refrigerant that has been dissipated heat from the high-pressure heat exchanger, and a low-pressure heat exchanger for evaporating the refrigerant that has been expanded by the expansion valve; a cooler core for cooling air introduced into a room; a heater core for heating the air introduced into the room; a cooler core-side heat medium circulation channel for circulating a heat medium between the cooler core and the low-pressure heat exchanger; a heater core-side heat medium circulation channel for circulating a heat medium between the heater core and the high-pressure heat exchanger; and a cooler core-side heat medium circulation channel or a heater core-side heat medium circulation channel. The refrigerant circuit comprises an external heat exchanger that exchanges heat between a refrigerated heat medium and outside air, a compressor, and / or a control unit that controls the flow rate of the heat medium flowing through the cooler core side heat medium circulation channel, and / or the flow rate of the heat medium flowing through the heater core side heat medium circulation channel, the refrigerant circuit includes a bypass channel that guides the refrigerant discharged from the compressor to the upstream or downstream of the low-pressure side heat exchanger, bypassing the high-pressure side heat exchanger, and the control unit provides a hot gas heating mode in which a portion of the refrigerant flows through the bypass channel and guides the heat medium that has flowed out of the high-pressure side heat exchanger to the heater core using the compressor as a heat source to heat the temperature-controlled object, and while the hot gas heating mode is being performed ,before A high-pressure refrigerant control mode that maintains the pressure of the refrigerant flowing through the high-pressure heat exchanger above a predetermined value, The control unit has, before the high-pressure refrigerant control mode, stops the flow of heat transfer medium to the high-pressure side heat exchanger and circulates the heat transfer medium between the cooler core side heat transfer medium circulation channel and the external heat exchanger to absorb heat from the outside air in an outside air heat absorption mode. It has.

[0010] A control method for a temperature control system according to one aspect of this disclosure is: A control method for a temperature control system comprising: a refrigerant circuit having a compressor for compressing a refrigerant, a high-pressure heat exchanger for releasing heat from the refrigerant compressed by the compressor, an expansion valve for expanding the refrigerant released heat by the high-pressure heat exchanger, and a low-pressure heat exchanger for evaporating the refrigerant expanded by the expansion valve; a cooler core for cooling air introduced into a room; a heater core for heating the air introduced into the room; a cooler core-side heat medium circulation channel for circulating a heat medium between the cooler core and the low-pressure heat exchanger; a heater core-side heat medium circulation channel for circulating a heat medium between the heater core and the high-pressure heat exchanger; and an external heat exchanger for exchanging heat between a heat medium led from the cooler core-side heat medium circulation channel or the heater core-side heat medium circulation channel and outside air, wherein the The refrigerant circuit includes a bypass channel that guides the refrigerant discharged from the compressor to the upstream or downstream of the low-pressure side heat exchanger, bypassing the high-pressure side heat exchanger, and has a hot gas heating mode in which a portion of the refrigerant flows through the bypass channel and the heat transfer medium that has flowed out of the high-pressure side heat exchanger with the compressor as a heat source is guided to the heater core to heat the temperature-controlled object; a high-pressure refrigerant control mode in which the pressure of the refrigerant flowing through the high-pressure side heat exchanger is maintained at or above a predetermined value while the hot gas heating mode is in operation; and an outside air heat absorption mode in which, before the high-pressure refrigerant control mode, the flow of the heat transfer medium to the high-pressure side heat exchanger is stopped and the heat transfer medium is circulated between the cooler core side heat transfer medium circulation channel and the external heat exchanger to absorb heat from the outside air. [Effects of the Invention]

[0011] This allows for a quick start to heating by suppressing temporary temperature drops. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram showing a vehicle air conditioning system according to the first embodiment of this disclosure, specifically illustrating the hot gas heating mode. [Figure 2] This is a schematic diagram showing the first startup control. [Figure 3] This is a schematic diagram showing the second startup control. [Figure 4] This is a schematic diagram showing the third startup control. [Figure 5] This is a flowchart illustrating the switching of startup control. [Figure 6] This is a schematic diagram showing a modified example of Figure 1. [Figure 7] This is a modified example of Figure 1, specifically a schematic diagram showing a direct expansion system. [Figure 8] This is a schematic diagram showing the case where the first startup control is performed in modified example 2 of Figure 7. [Modes for carrying out the invention]

[0013] Embodiments relating to this disclosure will be described below with reference to the drawings. [First Embodiment] The first embodiment of this disclosure will be described below with reference to Figure 1 and other figures. Figure 1 shows a schematic diagram of the vehicle air conditioning system (temperature control system) 1 according to this embodiment. The vehicle air conditioning system 1 includes a refrigerant circuit 3, a heat transfer medium circulation channel 5 on the heater core side, and a heat transfer medium circulation channel 7 on the cooler core side.

[0014] The refrigerant circuit 3 includes a compressor 10 that compresses the refrigerant, a condenser (high-pressure side heat exchanger) 11 that condenses the refrigerant compressed by the compressor 10, an expansion valve 12 that expands the refrigerant condensed by the condenser 11, an evaporator (low-pressure side heat exchanger) 13 that evaporates the refrigerant expanded by the expansion valve 12, and an accumulator 14 that separates the gas and liquid of the refrigerant led from the evaporator 13. As the compressor 10, for example, a scroll compressor or a rotary compressor is used. The operation of the refrigerant circuit 3 is controlled by a control unit (not shown).

[0015] A bypass passage 15 is provided so that the refrigerant discharged from the compressor 10 bypasses the condenser 11. The upstream end of the bypass passage 15 is connected between the compressor 10 and the condenser 11, and the downstream end of the bypass passage 15 is connected between the expansion valve 12 and the evaporator 13.

[0016] A bypass expansion valve 16 is provided in the bypass passage 15. By the bypass expansion valve 16, the high-pressure refrigerant discharged from the compressor 10 is expanded, and the flow rate of the refrigerant flowing through the bypass passage 15 is adjusted. The opening degree of the bypass expansion valve 16 is adjusted by the control unit.

[0017] As described above, by connecting the downstream end of the bypass passage 15 between the expansion valve 12 and the evaporator 13, by adjusting the expansion valve 12 and the bypass expansion valve 16 in the control unit, the variation in the enthalpy of the refrigerant sucked into the compressor 10 can be suppressed, and the refrigerant flowing through the bypass passage 15 and the refrigerant flowing through the condenser 11 can be mixed inside the evaporator 13.

[0018] The heater core side heat medium circulation passage 5 is a passage that mainly supplies warm water (heat medium, coolant) heated by the condenser 11 to the heater core 18 and returns the warm water flowing out from the heater core 18 to the condenser 11.

[0019] An upstream three-way valve 20a is provided on the upstream side (upper side in Figure 1) of the heater core 18, and a downstream three-way valve 20b is provided on the downstream side (lower side in Figure 1) of the heater core 18. The opening degree of the upstream three-way valve 20a is controlled by the control unit, allowing hot water from the heater core side heat transfer medium circulation channel 5 and cold water from the cooler core side heat transfer medium circulation channel 7 to flow to the heater core 18. The downstream three-way valve 20b is controlled by the control unit, allowing hot water flowing out of the heater core 18 to flow to the heater core side heat transfer medium circulation channel 5 and the cooler core side heat transfer medium circulation channel 7. The upstream three-way valve 20a and the downstream three-way valve 20b (hereinafter collectively referred to as the "heater core flow control valve 20") are controlled synchronously by a single actuator. Furthermore, this disclosure is not limited to the three-way valve described above, and other three-way valves or two-way valves may be combined.

[0020] A hot water pump (heater core side pump) 22 is provided downstream of the condenser 11 in the heater core side heat transfer fluid circulation channel 5. The rotational speed, i.e., the flow rate, of the hot water pump 22 is controlled by the control unit.

[0021] The cooler core side heat transfer fluid circulation channel 7 is a channel that primarily supplies chilled water (heat transfer fluid, coolant) cooled in the evaporator 13 to the cooler core 28, and returns the chilled water that flows out of the cooler core 28 to the evaporator 13.

[0022] An upstream three-way valve 30a is provided on the upstream side (upper side in Figure 1) of the cooler core 28, and a downstream three-way valve 30b is provided on the downstream side (lower side in Figure 1) of the cooler core 28. The opening degree of the upstream three-way valve 30a is controlled by the control unit, and it controls the flow of cold water from the cooler core side heat transfer medium circulation channel 7 and hot water from the heater core side heat transfer medium circulation channel 5. Coola Core 28The cooler core side downstream three-way valve 30b is controlled by the control unit and can direct the chilled water flowing out of the cooler core 28 to the cooler core side heat transfer medium circulation channel 7 and the heater core side heat transfer medium circulation channel 5. The cooler core side upstream three-way valve 30a and the cooler core side downstream three-way valve 30b (hereinafter collectively referred to as the "cooler core side flow control valve 30") are controlled synchronously by a single actuator. Note that this disclosure is not limited to the three-way valve described above, and other three-way valves or two-way valves may be combined.

[0023] A chilled water pump (cooler core side pump) 32 is provided downstream of the evaporator 13 in the cooler core side heat transfer fluid circulation channel 7. The rotational speed, i.e., the flow rate, of the chilled water pump 32 is controlled by the control unit.

[0024] The heater core 18 and cooler core 28 are used as an HVAC (Heating Ventilation and Air Conditioning) system (not shown). As shown by the white arrow in Figure 1 indicating airflow A1, the air cooled by the cooler core 28 is heated by the heater core 18 and then guided into the vehicle's passenger compartment.

[0025] An external heat exchanger 38 is connected to the heat transfer medium circulation channel 5 on the heater core side and the heat transfer medium circulation channel 7 on the cooler core side. The external heat exchanger 38 exchanges heat between hot water or chilled water and outside air.

[0026] An external heat exchanger side upstream three-way valve 40a is provided on the upstream side (upper side in Figure 1) of the external heat exchanger 38, and an external heat exchanger side downstream three-way valve 40b is provided on the downstream side (lower side in Figure 1) of the external heat exchanger 38. The opening degree of the external heat exchanger side upstream three-way valve 40a is controlled by the control unit, allowing chilled water from the cooler core side heat medium circulation channel 7 and hot water from the heater core side heat medium circulation channel 5 to flow to the external heat exchanger 38. The external heat exchanger side downstream three-way valve 40b is controlled by the control unit, allowing hot water or chilled water that has flowed out of the external heat exchanger 38 to flow to the cooler core side heat medium circulation channel 7 and the heater core side heat medium circulation channel 5. The external heat exchanger side upstream three-way valve 40a and the external heat exchanger side downstream three-way valve 40b (hereinafter collectively referred to as the "external heat exchanger side flow control valve 40") are synchronously controlled by a single actuator. Furthermore, this disclosure is not limited to the three-way valve described above, and other three-way valves or two-way valves may be combined.

[0027] The control unit consists of, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions are stored in the storage medium in the form of a program, for example. The CPU reads this program into the RAM and performs information processing and calculations to realize the various functions. The program may be pre-installed in ROM or other storage media, provided stored in a computer-readable storage medium, or distributed via wired or wireless communication. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memory.

[0028] Next, the operation of the operating mode using the vehicle air conditioning system 1 with the above configuration will be described.

[0029] <Hot gas heating mode> Figure 1 shows the hot gas heating mode. This mode is used when the outside temperature is extremely low, such as in winter, and sufficient heating capacity cannot be obtained with heat pump operation.

[0030] In this figure, channels carrying hot water are shown with solid lines, channels carrying cold water are shown with dashed lines, and channels without a heat transfer medium (cold or hot water) are shown with dotted lines. This notation is consistent throughout all subsequent figures.

[0031] In the refrigerant circuit 3, the refrigerant compressed by the compressor 10 is sent to the condenser 11 where it condenses. As the refrigerant condenses, the latent heat of condensation is transferred to the hot water, which is the heat transfer medium flowing through the condenser 11, causing it to heat up.

[0032] The liquid refrigerant exiting the condenser 11 is depressurized by the expansion valve 12 and guided to the evaporator 13. In the evaporator 13, the refrigerant evaporates, and the latent heat of vaporization is absorbed from the chilled water, which is the heat transfer medium circulating in the evaporator 13, thereby cooling the chilled water.

[0033] A portion of the refrigerant discharged from the compressor 10 is guided to the upstream side of the evaporator 13 through the bypass channel 15. The refrigerant flowing through the bypass channel 15 is expanded and its flow rate is controlled by the bypass expansion valve 16.

[0034] The flow rate through the bypass channel 15 is determined by the control unit based on the opening of the bypass expansion valve 16 and the expansion valve 12. At this time, the expansion valve 12 is controlled not to be completely closed, allowing refrigerant to flow. In other words, the entire amount of refrigerant is not allowed to flow through the bypass channel 15. This is because if the expansion valve 12 is completely closed, the refrigerant will condense and liquefy in the condenser 11 and accumulate, and the liquid refrigerant stored in the accumulator 14 will move to the condenser 11, potentially increasing the pressure of the low-pressure refrigerant drawn in by the compressor 10.

[0035] In hot gas heating mode, a portion of the refrigerant is diverted through the bypass channel 15 to increase the low pressure of the refrigerant and thereby increase the heating capacity.

[0036] After being heated in the condenser 11, the hot water is circulated through the heater core side heat transfer medium circulation channel 5 by the hot water pump 22. In the hot gas heating mode shown in Figure 1, the heater core side flow control valve 20 is fully opened by the control unit. As a result, heating is performed by the circulation of hot water through the heater core 18.

[0037] The control unit completely closes the cooler core side flow control valve 30 and stops the chilled water pump 32. This prevents chilled water from flowing through the cooler core side heat transfer medium circulation channel 7. In other words, in hot gas heating mode, no heat exchange with the outside air takes place in the cooler core 28.

[0038] The control unit completely closes the external heat exchanger side flow control valve 40. As a result, no heat exchange with the outside air takes place in the external heat exchanger 38.

[0039] As described above, in hot gas heating mode, heating operation is performed using the compressor 10 as a heat source while increasing the pressure value of the low-pressure refrigerant by flowing a portion of the refrigerant through the bypass channel 15.

[0040] <Startup control> When the vehicle air conditioning system 1 starts heating operation using the hot gas heating mode described in Figure 1 from a sufficiently cooled state, the rise in the pressure of the high-pressure refrigerant is slowed due to heat dissipation from the refrigerant to the hot water in the condenser 11, the compressor power does not increase, and the heating capacity does not increase, resulting in a slow start-up of heating. Furthermore, in order to suppress heat dissipation from the refrigerant to the hot water during startup, if hot water is not flowed into the condenser 11 until the refrigerant temperature or refrigerant pressure exceeds a predetermined value, and then the system switches to the hot gas heating mode, if hot water is suddenly flowed into the condenser 11, the amount of heat exchange with the high-pressure refrigerant in the condenser 11 changes rapidly, causing the pressure of the high-pressure refrigerant to drop and potentially reducing the heating capacity. Therefore, the startup control described below is performed. The startup control includes the first startup control in Figure 2, the second startup control in Figure 3, and the third startup control in Figure 4.

[0041] <<First startup control (outside air heat absorption mode)>> Figure 2 shows the first startup control. In the first startup control, an outside air heat absorption mode is used, in which heat is absorbed from the outside air using the external heat exchanger 38. The first startup control is performed, for example, when starting up the compressor 10.

[0042] The control unit completely closes the heater core side flow control valve 20 and the cooler core side flow control valve 30. This prevents hot water from flowing through the heater core side heat transfer medium circulation channel 5 and prevents cold water from flowing through the cooler core side heat transfer medium circulation channel 7.

[0043] Meanwhile, the control unit fully opens the chilled water side flow path of the external heat exchanger side flow control valve 40 and starts the chilled water pump 32 while keeping the hot water pump 22 stopped. As a result, chilled water flows to the external heat exchanger 38. In the external heat exchanger 38, the chilled water absorbs heat from the outside air, and the refrigerant is heated up in the evaporator 13.

[0044] The first startup mode is performed under conditions where the ambient temperature is greater than the temperature of the chilled water flowing through the external heat exchanger 38, i.e., under conditions where the chilled water can absorb heat.

[0045] <<Second startup control (outside air heat absorption stop mode)>> Figure 3 shows the second startup control. In the second startup control, the outside air heat exchange with the outside air is stopped, and the refrigerant temperature is raised in an outside air heat absorption stop mode.

[0046] In the first startup control shown in Figure 2, if the amount of heat absorbed from the outside air falls below a predetermined value, the second startup control is performed.

[0047] The control unit completely closes the heater core side flow control valve 20, the cooler core side flow control valve 30, and the external heat exchanger side flow control valve 40. This prevents hot water from flowing through the heater core side heat transfer medium circulation channel 5, chilled water from flowing through the cooler core side heat transfer medium circulation channel 7, and chilled and hot water from flowing to the external heat exchanger 38. The hot water pump 22 and chilled water pump 32 are stopped. This prevents chilled water from flowing to the external heat exchanger 38, as in the first startup control. Therefore, even if the chilled water temperature becomes higher than the ambient temperature, the chilled water will not dissipate heat in the external heat exchanger 38. The refrigerant is raised to the desired temperature or pressure by the operation of the compressor 10 alone.

[0048] <<Third Startup Control (High-Pressure Refrigerant Control Mode)>> Figure 4 shows the third startup control. The third startup control is a high-pressure refrigerant control mode that controls the pressure of the high-pressure refrigerant when hot water is started to flow into the condenser 11.

[0049] In the second startup control shown in Figure 3, once the refrigerant temperature or pressure reaches the desired value, the third startup control is performed.

[0050] The control unit opens the heater core side flow control valve 20 and completely closes the cooler core side flow control valve 30 and the external heat exchanger side flow control valve 40. The hot water pump 22 is started, while the chilled water pump 32 remains stopped. This starts the flow of hot water through the heater core side heat transfer medium circulation channel 5. Meanwhile, chilled water is not flowed through the cooler core side heat transfer medium circulation channel 7, and neither chilled nor hot water is flowed to the external heat exchanger 38. This starts the flow of hot water through the heater core 18 to begin heating.

[0051] The flow rate of hot water flowing to the condenser 11 is gradually increased. The control unit increases the hot water flow rate at a predetermined rate by adjusting the rotational speed of the hot water pump 22 and / or the opening degree of the upstream three-way valve 20a on the heater core side and / or the opening degree of the downstream three-way valve 20b on the heater core side.

[0052] The control unit controls the pressure value of the high-pressure refrigerant flowing into the condenser 11 to be above a predetermined target value, corresponding to the amount of heat exchange in the condenser 11, which changes in response to the increase in the flow rate of hot water flowing into the condenser 11. The control unit maintains the high-pressure refrigerant at the target value by, for example, adjusting the rotational speed of the compressor 10, the opening degree of the expansion valve 12, the opening degree of the bypass expansion valve 16, etc. Alternatively, the control unit may control the power of the compressor 10 so that the pressure value of the high-pressure refrigerant is above a predetermined target value. The power of the compressor 10 can be calculated by the control unit from the power input to the electric motor of the compressor 10 from the inverter. By controlling the high-pressure refrigerant in this way to maintain the target value, changes in the refrigerant pressure in the condenser 11 are suppressed, and a temporary decrease in heating capacity is suppressed.

[0053] Figure 5 shows flowcharts of the first to third startup controls described above. When the startup control begins, the control unit determines in step S1 whether the refrigerant pressure or refrigerant temperature is above a predetermined value.

[0054] Specifically, it is determined whether one of the following relationships is satisfied until the amount of heat absorbed from the outside air falls below a predetermined value. Low-pressure refrigerant temperature > ambient temperature Low-pressure side refrigerant pressure > Pressure at which the saturation temperature is equal to the ambient temperature High-pressure side refrigerant temperature > Target temperature High-pressure side refrigerant pressure > Pressure at which the saturation temperature reaches the target temperature.

[0055] If "No" is determined in step S1, that is, if it is determined that heat can be absorbed from the outside air, the process proceeds to step S2 and the first startup control shown in Figure 2 is performed.

[0056] If "Yes" is determined in step S1, that is, if the amount of heat absorbed from the outside air is determined to be less than a predetermined value, the process proceeds to step S3.

[0057] In step S3, the control unit determines whether the refrigerant pressure or refrigerant temperature is above a predetermined value. The predetermined value used in step S3 is a value greater than the predetermined value used in step S1.

[0058] Specifically, it is determined whether one of the following relationships is satisfied until the temperature or pressure of the refrigerant becomes sufficiently high. Low-pressure refrigerant temperature > Saturation temperature at target pressure Low-pressure side refrigerant pressure > Target pressure High-pressure side refrigerant temperature > Target temperature High-pressure side refrigerant pressure > Pressure at which the saturation temperature reaches the target temperature.

[0059] If "No" is determined in step S3, that is, if it is determined that the refrigerant temperature or pressure does not meet the required conditions, the process proceeds to step S4, where the second startup control shown in Figure 3 is performed.

[0060] If "Yes" is determined in step S3, that is, if it is determined that the temperature or pressure of the refrigerant has become sufficiently high, the process proceeds to step S5.

[0061] In step S5, the third startup control shown in Figure 4 is performed to gradually increase the hot water flow rate. Then, the system transitions to the hot gas heating mode shown in Figure 1.

[0062] The effects and advantages of this embodiment, as described above, are as follows. In hot gas heating mode, the low pressure of the refrigerant can be increased by providing a bypass channel 15 that bypasses the condenser 11 and directs the refrigerant upstream of the evaporator 13. This increases the heating capacity in hot gas heating mode. In hot gas heating mode, a sudden increase in the flow rate of hot water through the condenser 11 can cause a rapid change in the amount of heat exchanged with the high-pressure refrigerant, potentially leading to a drop in refrigerant pressure and a decrease in heating capacity. Therefore, a high-pressure refrigerant control mode is provided as a third startup control to maintain the refrigerant pressure flowing through the condenser 11 above a predetermined value after switching to hot gas heating mode (see Figure 4). This suppresses changes in refrigerant pressure in the condenser 11, preventing a temporary drop in heating capacity and allowing heating to start quickly.

[0063] In the third startup control, before the hot water is flowed to the condenser 11, the flow of hot water to the condenser 11 is stopped to raise the pressure value of the high-pressure refrigerant as much as possible. Then, as the first startup control, chilled water is circulated between the cooler core side heat transfer medium circulation channel 7 and the external heat exchanger 38 to absorb heat from the outside air. This increases the low pressure of the refrigerant using the outside air, thereby increasing the high pressure of the refrigerant.

[0064] As a second startup control measure, if the amount of heat absorbed from the outside air falls below a predetermined value, an increase in the low pressure of the refrigerant due to heat absorption from the outside air cannot be expected, so the flow of chilled water to the external heat exchanger 38 is stopped. In particular, if the chilled water temperature becomes higher than the outside air temperature and the amount of heat absorbed becomes negative, heat will be released to the outside air. In this case, the flow of the heat transfer medium is stopped because it will have an adverse effect on the hot gas heating mode.

[0065] Furthermore, the above-described embodiment can be modified as follows. <Example 1> In the embodiment shown in Figure 1, etc., an accumulator 14 is used, but a configuration with a receiver 42 may also be used, as shown in Figure 6. The receiver 42 is provided between the condenser 11 and the expansion valve 12 and stores the liquid refrigerant that flows out of the condenser 11. Alternatively, as shown in Figure 6, the downstream end of the bypass passage 15 may be connected between the evaporator 13 and the compressor 10. This reduces the amount of refrigerant circulated in the evaporator 13, thereby reducing pressure loss due to the refrigerant.

[0066] <Modification 2> As shown in Figure 7, the above-described embodiment can also be applied to a direct expansion system. In this figure, the external heat exchanger 38 in Figure 1, etc., where chilled water and air exchange heat, becomes an external heat exchanger 38' where refrigerant and air exchange heat. Also, the cooler core 28 in Figure 1, etc., where chilled water or hot water (heat transfer medium) and air exchange heat, becomes a cooler core 28' where refrigerant and air exchange heat.

[0067] A three-way valve 43 is provided between the external heat exchanger 38' and the expansion valve 12. The three-way valve 43 can switch the flow of refrigerant led from the expansion valve 12 to either the accumulator 14 side or the external heat exchanger 38', according to a command from the control unit.

[0068] A second expansion valve 44 is provided between the external heat exchanger 38' and the cooler core 28'. A second bypass passage 46 is provided between the outlet side of the cooler core 28' and the external heat exchanger 38'. The second bypass passage 46 is provided with an on / off valve 48 that is opened and closed by the control unit. A hot water flow rate control valve 49, whose opening degree is controlled by the control unit, is provided on the upstream side of the heater core 18. The hot water flow rate control valve 49 may also be provided on the downstream side of the heater core 18.

[0069] Even with the direct expansion system shown in Figure 7, hot gas heating mode and 1st to 3rd startup control are possible. Specifically, as shown in Figure 7, in the hot gas heating mode and the third startup control, the second expansion valve 44 and the on-off valve 48 are fully closed, and the three-way valve 43 is switched so that the refrigerant introduced from the expansion valve 12 flows to the accumulator 14. As a result, the refrigerant circulates without flowing to the external heat exchanger 38' and the cooler core 28'. When adjusting the flow rate of hot water during the third startup control, the control unit controls the hot water flow rate adjustment valve 49.

[0070] When performing the first startup control described above (see Figure 2), as shown in Figure 8, the control unit stops the hot water pump 22, fully closes the second expansion valve 44, fully opens the on-off valve 48, and switches the three-way valve 43 so that the refrigerant flows to the external heat exchanger 38'. As a result, the refrigerant, which has been depressurized by the expansion valve 12, is guided to the external heat exchanger 38' and absorbs heat from the outside air.

[0071] Furthermore, in the embodiments described above, the first to third startup controls were used in this order, but this disclosure is not limited thereto, and it is sufficient to use at least the third startup control.

[0072] The temperature control systems and their control methods described in each of the embodiments described above can be understood, for example, as follows.

[0073] A temperature control system (1) according to a first aspect of this disclosure includes a refrigerant circuit (3) having a compressor (10) for compressing a refrigerant, a high-pressure side heat exchanger (11) for releasing heat from the refrigerant compressed by the compressor, an expansion valve (12) for expanding the refrigerant released heat from the high-pressure side heat exchanger, and a low-pressure side heat exchanger (13) for evaporating the refrigerant expanded by the expansion valve; a cooler core (28) for cooling air introduced into a room; a heater core (18) for heating the air introduced into the room; a cooler core side heat medium circulation channel (7) for circulating a heat medium between the cooler core and the low-pressure side heat exchanger; a heater core side heat medium circulation channel (5) for circulating a heat medium between the heater core and the high-pressure side heat exchanger; and a heat medium and outside air led from the cooler core side heat medium circulation channel or the heater core side heat medium circulation channel. The refrigerant circuit includes an external heat exchanger (38) that exchanges heat with the compressor, and a control unit that controls the flow rate of the heat medium flowing through the cooler core side heat medium circulation channel and / or the flow rate of the heat medium flowing through the heater core side heat medium circulation channel. The refrigerant circuit includes a bypass channel (15) that guides the refrigerant discharged from the compressor to the upstream or downstream of the low-pressure side heat exchanger, bypassing the high-pressure side heat exchanger. The control unit has a hot gas heating mode in which a portion of the refrigerant flows through the bypass channel and guides the heat medium that has flowed out of the high-pressure side heat exchanger to the heater core using the compressor as a heat source to heat the temperature-controlled object, and a high-pressure refrigerant control mode in which the pressure of the refrigerant flowing through the high-pressure side heat exchanger is maintained at or above a predetermined value while the hot gas heating mode is being performed.

[0074] By providing a bypass channel that bypasses the high-pressure heat exchanger and directs the refrigerant upstream or downstream of the low-pressure heat exchanger, the low-pressure pressure of the refrigerant can be increased. This allows for increased heating capacity in hot gas heating mode. If the flow of the heat transfer medium to the high-pressure heat exchanger is abruptly changed after switching to hot gas heating mode, the amount of heat exchanged with the high-pressure refrigerant may change rapidly, causing a drop in refrigerant pressure and potentially reducing heating capacity. Therefore, a high-pressure refrigerant control mode has been implemented to maintain the pressure of the refrigerant flowing through the high-pressure heat exchanger above a predetermined value after switching to hot gas heating mode. This suppresses changes in refrigerant pressure in the high-pressure heat exchanger, preventing a temporary drop in heating capacity and allowing heating to start quickly. In high-pressure refrigerant control mode, the flow rate of the heat transfer medium in the heater core side heat transfer medium circulation channel, the opening degree of the expansion valve, and the rotation speed of the compressor are adjusted. In the case of a direct expansion type where the refrigerant flows directly to the cooler core or outdoor heat exchanger, the heat transfer medium flowing through each heat transfer medium circulation is the same refrigerant that flows through the refrigerant circuit.

[0075] In the first embodiment, the temperature control system according to a second aspect of the present disclosure has an outside air heat absorption mode in which, before the high-pressure refrigerant control mode, the control unit stops the flow of the heat transfer medium to the high-pressure side heat exchanger and circulates the heat transfer medium between the cooler core side heat transfer medium circulation channel and the external heat exchanger to absorb heat from the outside air.

[0076] In high-pressure refrigerant control mode, before the heat transfer medium flows to the high-pressure side heat exchanger, the flow of the heat transfer medium to the high-pressure side heat exchanger is stopped to raise the pressure of the high-pressure refrigerant as much as possible. Then, the heat transfer medium is circulated between the cooler core side heat transfer medium circulation channel and the external heat exchanger to absorb heat from the outside air. This allows the high pressure of the refrigerant to be increased by increasing the low pressure of the refrigerant using the outside air.

[0077] In the third aspect of the present disclosure, the temperature control system, in the second aspect, has an outside air heat absorption stop mode in which the control unit stops the flow of the heat transfer medium to the external heat exchanger when the amount of heat absorbed from the outside air in the outside air heat absorption mode falls below a predetermined value.

[0078] If the amount of heat absorbed from the outside air falls below a predetermined value, the increase in the low pressure of the refrigerant due to heat absorption from the outside air cannot be expected, so the flow of the heat transfer medium to the external heat exchanger is stopped. In particular, if the temperature of the heat transfer medium becomes higher than the outside air temperature and the amount of heat absorbed becomes negative, heat will be released into the outside air. In this case, it is necessary to stop the flow of the heat transfer medium as it will negatively affect the hot gas heating mode. In the outside air heat absorption stop mode, it is preferable to stop the flow of the heat transfer medium to the high-pressure side heat exchanger, similar to the outside air heat absorption mode. Furthermore, it is preferable to transition to the high-pressure refrigerant control mode described above after the outside air heat absorption stop mode.

[0079] A control method for a temperature control system according to a first aspect of this disclosure includes a refrigerant circuit having a compressor for compressing a refrigerant, a high-pressure heat exchanger for releasing heat from the refrigerant compressed by the compressor, an expansion valve for expanding the refrigerant released heat by the high-pressure heat exchanger, and a low-pressure heat exchanger for evaporating the refrigerant expanded by the expansion valve; a cooler core for cooling air introduced into a room; a heater core for heating the air introduced into the room; a cooler core-side heat medium circulation channel for circulating a heat medium between the cooler core and the low-pressure heat exchanger; a heater core-side heat medium circulation channel for circulating a heat medium between the heater core and the high-pressure heat exchanger; and the cooler core-side heat medium circulation channel or the heater A control method for a temperature control system comprising: an external heat exchanger that exchanges heat between a heat transfer medium introduced from a core-side heat transfer medium circulation channel and outside air, wherein the refrigerant circuit includes a bypass channel that guides the refrigerant discharged from the compressor to the upstream or downstream of the low-pressure side heat exchanger, bypassing the high-pressure side heat exchanger, and includes a hot gas heating mode in which a portion of the refrigerant flows from the bypass channel and the heat transfer medium flowing out of the high-pressure side heat exchanger, using the compressor as a heat source, is guided to the heater core to heat the temperature control target; and a high-pressure refrigerant control mode in which, while the hot gas heating mode is being performed, the pressure of the refrigerant flowing through the high-pressure side heat exchanger is maintained at or above a predetermined value. [Explanation of symbols]

[0080] 1. Vehicle air conditioning system (temperature control system) 3. Refrigerant Circuit 5 Heater core side heat transfer fluid circulation channel 7. Cooler core side heat transfer fluid circulation channel 10 Compressor 11. Condenser (High-pressure side heat exchanger) 12 Expansion valve 13. Evaporator (low-pressure heat exchanger) 14 Accumulator 15 Bypass channel 16 Bypass expansion valve 18 Heater core 20 Heater core side flow control valve 20a Three-way valve upstream of heater core 20b Three-way valve downstream of the heater core 22. Hot water pump (heater core side pump) 28,28' Coolacore 30 Cooler core side flow control valve 30a Cooler core side upstream three-way valve 30b Cooler core side downstream three-way valve 32. Chilled water pump (cooler core side pump) 38,38' external heat exchanger 40 External heat exchanger side flow control valve 40a External heat exchanger side upstream three-way valve 40b External heat exchanger side downstream three-way valve 42 receivers 43 Three-way valve 44. Second expansion valve 46 Second Bypass Channel 48. Shut-off valves 49 Hot water flow control valve

Claims

1. A refrigerant circuit having a compressor for compressing the refrigerant, a high-pressure heat exchanger for releasing heat from the refrigerant compressed by the compressor, an expansion valve for expanding the refrigerant that has released heat from the high-pressure heat exchanger, and a low-pressure heat exchanger for evaporating the refrigerant that has expanded in the expansion valve, A cooler core that cools the air introduced into the room, A heater core for heating the air introduced into the aforementioned room, A cooler core side heat transfer medium circulation channel for circulating the heat transfer medium between the cooler core and the low-pressure side heat exchanger, A heater core-side heat transfer medium circulation channel for circulating the heat transfer medium between the heater core and the high-pressure side heat exchanger, An external heat exchanger that exchanges heat between the heat medium introduced from the heat medium circulation channel on the cooler core side or the heat medium circulation channel on the heater core side and the outside air, A control unit that controls the compressor and / or the flow rate of the heat medium flowing through the heat medium circulation channel on the cooler core side and / or the flow rate of the heat medium flowing through the heat medium circulation channel on the heater core side, Equipped with, The refrigerant circuit includes a bypass channel that guides the refrigerant discharged from the compressor to the upstream or downstream of the low-pressure heat exchanger, bypassing the high-pressure heat exchanger. The control unit provides a hot gas heating mode in which a portion of the refrigerant flows through the bypass channel and the heat transfer medium discharged from the high-pressure side heat exchanger is guided to the heater core using the compressor as a heat source to heat the temperature-controlled object. While the hot gas heating mode is in operation, a high-pressure refrigerant control mode is in place to maintain the pressure of the refrigerant flowing through the high-pressure heat exchanger above a predetermined value. It has, The control unit has an outside air heat absorption mode in which, before the high-pressure refrigerant control mode, the flow of the heat transfer medium to the high-pressure side heat exchanger is stopped, and the heat transfer medium is circulated between the cooler core side heat transfer medium circulation channel and the external heat exchanger to absorb heat from the outside air.

2. The temperature control system according to claim 1, wherein the control unit has an outside air heat absorption stop mode that stops the flow of the heat transfer medium to the external heat exchanger when the amount of heat absorbed from the outside air in the outside air heat absorption mode falls below a predetermined value.

3. A refrigerant circuit having a compressor for compressing a refrigerant, a high-pressure side heat exchanger for releasing heat from the refrigerant compressed by the compressor, an expansion valve for expanding the refrigerant that has released heat from the high-pressure side heat exchanger, and a low-pressure side heat exchanger for evaporating the refrigerant that has expanded in the expansion valve, A cooler core that cools the air introduced into the room, A heater core for heating the air introduced into the aforementioned room, A cooler core side heat transfer medium circulation channel for circulating the heat transfer medium between the cooler core and the low-pressure side heat exchanger, A heater core-side heat transfer medium circulation channel for circulating the heat transfer medium between the heater core and the high-pressure side heat exchanger, An external heat exchanger that exchanges heat between the heat medium introduced from the heat medium circulation channel on the cooler core side or the heat medium circulation channel on the heater core side and the outside air, A control method for a temperature control system equipped with, The refrigerant circuit includes a bypass channel that guides the refrigerant discharged from the compressor to the upstream or downstream of the low-pressure heat exchanger, bypassing the high-pressure heat exchanger. A hot gas heating mode is provided in which a portion of the refrigerant is flowed through the bypass channel, and the heat transfer medium that has flowed out of the high-pressure side heat exchanger is guided to the heater core using the compressor as a heat source to heat the temperature-controlled object. While the hot gas heating mode is in operation, a high-pressure refrigerant control mode is in place to maintain the pressure of the refrigerant flowing through the high-pressure heat exchanger above a predetermined value. Prior to the high-pressure refrigerant control mode, there is an outside air heat absorption mode in which the flow of heat transfer medium to the high-pressure side heat exchanger is stopped, and the heat transfer medium is circulated between the cooler core side heat transfer medium circulation channel and the external heat exchanger to absorb heat from the outside air. A control method for a temperature control system having the following features.

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