JP4274886B2 - Heat pump air conditioner - Google Patents

Description

  The present invention relates to a heat pump air conditioner that performs heating using a heat pump cycle.

In order to realize a comfortable indoor temperature environment, an air conditioner using a heat pump cycle has been widely used. However, when heating is performed using a heat pump cycle, the water temperature in the outside air freezes on the surface of the heat sink due to the outside air temperature and the surface temperature of the heat sink, and the heat exchange efficiency of the heat sink decreases. There was a problem that the ventilation resistance of the heat absorber deteriorated. Therefore, as shown in Patent Document 1, the frost formation state of the heat absorber is determined, and when the frost is formed, control is performed to perform a defrosting operation.
JP-A-8-197937

  However, in such a conventional heat pump cycle frost detection method, since frost formation is detected only from the low pressure of the heat pump cycle, it is difficult to accurately determine the frost formation state. In addition, the frost phenomenon is largely attributed to the amount of moisture (humidity) contained in the outside air, and when trying to construct a device that detects the frost phenomenon in combination with humidity detection, a sensor for accurately detecting the humidity. However, it is difficult to employ this humidity detection method.

  Accordingly, an object of the present invention is to provide a heat pump type air conditioner that is relatively inexpensive and can detect a frosting phenomenon easily and accurately.

In order to solve the above-mentioned problem, the invention according to claim 1 is provided in a compressor that pressurizes the refrigerant circulating in the pipe and the air conditioning duct, and transmits heat of the refrigerant pressurized to the compressor to the conditioned air. An indoor heat exchanger, an expansion valve that adiabatically expands the refrigerant radiated by the indoor heat exchanger, an outdoor heat exchanger that transfers the heat of outdoor air to the adiabatically expanded refrigerant, and the air conditioning duct. A heat pump air conditioner provided with a switching door that switches between a heating passage through which the conditioned air passing through the air conditioning duct passes through the indoor heat exchanger and a bypass passage through which the conditioned air bypasses the indoor heat exchanger. When a temperature sensor is provided at the refrigerant inlet of the outdoor heat exchanger, the frost formation state of the outdoor heat exchanger is estimated from the refrigerant temperature detected by the temperature sensor, and it is determined that the frost state is present. , The outdoor heat exchanger The defrosting mode operation is performed to remove the frost that has arrived. In the defrosting mode, the refrigerant passes through the compressor in the order of the indoor heat exchanger and the outdoor heat exchanger and returns to the compressor. The bypass passage is blocked, and the conditioned air is allowed to pass through the heating passage .

  In order to solve the above-mentioned problem, in the heat pump type air conditioner according to claim 1, at least the room temperature is detected, and the refrigerant discharge amount of the compressor changes according to the target room temperature. Features.

  According to the first aspect of the present invention, by estimating the frost formation state of the outdoor heat exchanger from the refrigerant temperature at the inlet of the outdoor heat exchanger, the outdoor heat exchange can be performed relatively inexpensively without complicating the heat pump cycle. The frosting state of the vessel can be determined.

  According to the second aspect of the invention, in addition to the effect of the first aspect of the invention, the refrigerant discharge amount of the compressor changes according to the target indoor temperature, thereby increasing the refrigerant discharge amount to the target indoor temperature. In addition to being able to adjust quickly, after reaching the target indoor temperature, the refrigerant discharge amount can be reduced to reduce the load on the compressor.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an operating state in a cooling mode of a heat pump air conditioner according to the present invention, FIG. 2 is a schematic diagram showing an operating state in a heating mode, and FIG. 3 is a schematic diagram showing an operating state in a dehumidifying mode. FIG. 4 is a schematic diagram showing an operation state in the defrost mode, and FIG. 5 is an explanatory diagram showing a flowchart for executing the defrost mode.

  The heat pump type air conditioner of the present embodiment shows a case where the heat pump type air conditioner is applied to a vehicle air conditioner, and uses carbon dioxide (CO2) phase-changed between a supercritical phase and a gas phase as a refrigerant. As shown in FIG. 4, the heat pump air conditioner 1 includes a compressor 2 that pressurizes the refrigerant, a sub gas cooler 3 that functions as a heater that exchanges heat between the pressurized refrigerant and the outside air, and an operation. The outdoor heat exchanger 4 that functions as a heat absorber and a radiator according to the mode, the first expansion valve 5 that adiabatically expands the refrigerant radiated by the sub gas cooler 3 and the outdoor heat exchanger 4, and the adiabatically expanded refrigerant evaporates. There are provided an evaporator 6 as a heat absorber and an inter-refrigerant heat exchanger 7 for exchanging heat between the high-pressure refrigerant on the downstream side of the outdoor heat exchanger 4 and the low-pressure refrigerant on the downstream side of the evaporator 6.

  The compressor 2 is a constant capacity compressor, and the number of revolutions is changed according to demand, the amount of refrigerant discharged is increased by increasing the number of revolutions, and the amount of refrigerant discharged is reduced by lowering the number of revolutions. ing. Further, the room temperature is detected, and the refrigerant discharge amount of the compressor 2 is controlled to change according to the temperature difference from the target room temperature.

  The sub gas cooler 3 is disposed in the air conditioning duct 8, and the refrigerant pressurized by the compressor 2 is introduced through the passage P1, and the heat generated when the refrigerant is pressurized is used as a heating heat source in the air conditioning duct 8. Heat is transmitted to the passing conditioned air, and the switching door 9 switches between a heating passage 8a through which the conditioned air passes through the sub gas cooler 3 and a bypass passage 8b that bypasses the sub gas cooler 3.

  The outdoor heat exchanger 4 is configured so that the refrigerant radiated by the sub gas cooler 3 is introduced through the passage P2 and is disposed in front of the vehicle so that heat can be exchanged with the outdoor air. Further, a temperature sensor 17 for measuring the refrigerant temperature is provided at the refrigerant inlet 4a portion of the outdoor heat exchanger 4, and the frost formation state of the outdoor heat exchanger 4 is estimated from the refrigerant temperature detected by the temperature sensor 17. It is like that.

  In the first expansion valve 5, the refrigerant cooled by the outdoor heat exchanger 4 is introduced through the passage P3. Further, the first expansion valve 5 has a variable throttle function, so that the throttle amount can be controlled, and is controlled so that the throttle valve is throttled as the outlet temperature of the outdoor heat exchanger 4 increases. . Furthermore, when the outdoor heat exchanger 4 outlet temperature of the refrigerant rises beyond the normal control range due to frost formation on the outdoor heat exchanger 4, it is controlled to forcibly open the throttle valve. .

  The evaporator 6 is disposed in the low pressure passage P4 located on the downstream side of the first expansion valve 5 and is disposed on the upstream side of the sub gas cooler 3 in the air conditioning duct 8 and is adiabatically expanded by the first expansion valve 5. Is introduced into the air conditioning duct 8 to take heat away from the conditioned air passing through the evaporator 6 to cool and dehumidify.

  The inter-refrigerant heat exchanger 7 performs the first expansion by exchanging heat between the high-pressure refrigerant in the relatively high temperature state downstream of the outdoor heat exchanger 4 and the low-pressure refrigerant adiabatically expanded by the evaporator 6 during the cooling operation. The refrigerant flowing into the valve 5 can be cooled and the refrigerant sucked into the compressor 2 can be heated.

  In the low pressure passage P4, an accumulator 10 is provided between the evaporator 6 and the inter-refrigerant heat exchanger 7, and the refrigerant passing through the evaporator 6 is gas-liquid separated by the accumulator 10, and only the gas-phase refrigerant is heated between the refrigerants. It passes through the exchanger 7 and is sucked into the compressor 2.

  A passage P2 connecting the sub-gas cooler 3 and the outdoor heat exchanger 4 is provided with a three-way valve 11. By switching the three-way valve 11, a route for connecting the outdoor heat exchanger 4 to the passage P2 (first switching position) And the path | route (2nd switching position) which connects the outdoor heat exchanger 4 to the return path | route P5 connected to the upstream of the accumulator 10 in the downstream of the evaporator 6 is switched.

  Further, the upstream side of the three-way valve 11 of the low pressure passage P2 and the passage P3 are communicated by a first bypass passage P6 provided with an electromagnetic valve 12, and at the downstream side of the inter-refrigerant heat exchanger 7 and the first expansion. The upstream side of the valve 5 and the outlet side of the outdoor heat exchanger 4 are communicated with each other by a second bypass passage P7 provided with a second expansion valve 13.

  In the passage P3, a first check valve 14 that allows refrigerant to pass from the outdoor heat exchanger 4 toward the inter-refrigerant heat exchanger 7 between the outdoor heat exchanger 4 and the communication portion of the first bypass passage P6. And a second check valve 15 that allows passage of the refrigerant in the direction of the outdoor heat exchanger 4 is provided downstream of the second expansion valve 13 in the second bypass passage P7. The return passage P5 is provided with a third check valve 16 that allows passage of refrigerant from the outdoor heat exchanger 4 to the compressor 2 in the return direction.

  And the heat pump type air conditioner 1 comprised in this way is drive | operated by the air_conditioning | cooling mode, heating mode, and dehumidification mode as FIG. 1-3 shows. Further, when the outdoor heat exchanger 4 is frosted, it is operated in the defrost mode as shown in FIG. In the schematic diagrams of FIGS. 1 to 4, a path through which the refrigerant flows is indicated by a solid line, and a path through which the refrigerant is not supplied is indicated by a broken line.

<Cooling mode>
In the cooling mode operation of the heat pump air conditioner 1, the refrigerant pressurized by the compressor 2 is changed to the sub-switch by switching the three-way valve 11 to the first switching position as shown in FIG. Gas cooler 3 → (three-way valve 11) → outdoor heat exchanger 4 → refrigerant heat exchanger 7 → first expansion valve 5 → evaporator 6 → accumulator 10 → refrigerant heat exchanger 7 The circulation route is configured.

  In the air conditioning duct 8, the conditioned air inflow side of the sub gas cooler 3 is blocked by the switching door 9, and only the cooling air that has passed through the evaporator 6 passes through the bypass passage 8a and is blown into the vehicle interior. Yes.

<Heating mode>
In the heating mode operation of the heat pump type air conditioner 1, as shown in FIG. 2, the first expansion valve 5 is shut off, the three-way valve 11 is switched to the second switching position, and the electromagnetic valve 12 is opened, whereby the compressor 2 The refrigerant pressurized in the sub-gas cooler 3 → (electromagnetic valve 12) → refrigerant heat exchanger 7 → second expansion valve 13 → outdoor heat exchanger 4 → (three-way valve 11) → accumulator 10 → refrigerant heat exchange. A circulation path is formed in which the gas passes through the container 7 and is sucked into the compressor 2.

  In the air conditioning duct 8, the opening degree of the bypass passage 8 b is adjusted by the switching door 9, and the conditioned air passes through the heating passage 8 a of the subgas cooler 3 and the throttled bypass passage 8 b to adjust the temperature of the heating air. As a result, air is blown into the passenger compartment. In this state, the evaporator 6 is not functioning.

<Dehumidification mode>
In the dehumidifying mode operation of the heat pump type air conditioner 1, the refrigerant pressurized by the compressor 2 by opening the first expansion valve 5 and opening the electromagnetic valve 12 as shown in FIG. A circulation path is formed in which the valve 12), the inter-refrigerant heat exchanger 7, the first expansion valve 5, the evaporator 6, the accumulator 10, and the inter-refrigerant heat exchanger 7 pass in this order and are sucked into the compressor 2.

  In the air conditioning duct 8, the opening degree of the bypass passage 8 b is adjusted by the switching door 9, and the conditioned air cooled through the evaporator 6 is heated through the heating passage 8 a of the subgas cooler 3, It is adjusted to an appropriate temperature and blown into the passenger compartment.

<Defrost mode>
The defrosting mode operation of the heat pump air conditioner 1 is executed to defrost when the outdoor heat exchanger 4 is frosted, and the three-way valve 11 is switched to the first switching position as shown in FIG. By shutting off the solenoid valve 12, the refrigerant pressurized by the compressor 2 is sub-gas cooler 3 → (three-way valve 11) → outdoor heat exchanger 4 → inter-refrigerant heat exchanger 7 → first expansion valve 5 → evaporator 6 A circulation path is formed in which the refrigerant passes through the order of the accumulator 10 → the heat exchanger 7 between refrigerants and is sucked into the compressor 2.

  That is, the refrigerant circulation path in the defrosting mode is the same as the refrigerant circulation path in the cooling mode, but the switching position of the switching door 9 in the air conditioning duct 8 is different, and the switching door 9 is the same as in the dehumidifying mode. The bypass air passage 8b is shut off, and the conditioned air cooled by passing through the evaporator 6 is heated through the heating passage 8a of the sub gas cooler 3 so as to be adjusted to an appropriate temperature and blown into the vehicle interior. It has become. Of course, even in this case, the opening degree of the bypass passage 8b can be adjusted by the switching door 9.

  Therefore, in the present embodiment, in order to automatically operate the defrost mode, the frost formation of the outdoor heat exchanger 4 is automatically detected, and the refrigerant is detected by the temperature sensor 17 provided in the refrigerant inlet 4a portion of the outdoor heat exchanger 4. When the temperature is detected and the refrigerant temperature is lower than the predetermined temperature, it is determined that the outdoor heat exchanger 4 is frosted, and the defrosting mode operation is performed. When the refrigerant temperature measured by the above becomes higher than another predetermined temperature, control is performed so as to return to the heating mode operation.

  In step S11, it is determined whether or not the outlet side conditioned air temperature TSC of the sub-gas cooler 3 is equal to or lower than a predetermined temperature (60 ° C. in the present embodiment). In order to reduce the amount of refrigerant circulating inside, the compressor 2 rotational speed is reduced (step S16).

  If the outlet side air-conditioning air temperature TSC of the sub-gas cooler 3 is 60 ° C. or less in step S11, the temperature difference ΔT between the target air-conditioning air temperature Xm and the outlet-side air-conditioning air temperature TSC of the sub-gas cooler 3 is It is determined whether or not there is a predetermined temperature difference (3.33 ° C. in this embodiment) or more (step S12).

  If the temperature difference ΔT is 3.33 ° C. or more in step S12, the heating capacity is insufficient, so the compressor 2 rotation speed is increased to increase the amount of refrigerant circulating in the cycle (step S14), If the temperature difference ΔT is smaller than 3.33 ° C., the heating capacity is appropriate, so that the compressor 2 rotation speed is maintained as it is to maintain the amount of refrigerant circulating in the cycle (step S15).

  After adjusting the heating capacity in steps S14 to S16, it is determined whether or not the outside air temperature is lower than a predetermined temperature (3 ° C. in the present embodiment) (step S20). If the outside air temperature is lower than 3 ° C., the process proceeds to step S22.

  In step S21, the refrigerant temperature on the inlet side of the outdoor heat exchanger 4 when the outside air temperature is relatively high is determined, and the refrigerant temperature on the inlet side of the outdoor heat exchanger 4 is determined from a predetermined temperature (−6 ° C. in the present embodiment). If it is higher, the process proceeds to step S25, and if the refrigerant temperature on the inlet side of the outdoor heat exchanger 4 is -6 ° C or lower, it is determined that the heat exchange portion of the outdoor heat exchanger 4 is frosted. Then, the heating mode operation is stopped and the defrosting mode operation is started.

  In step S22, the refrigerant temperature on the inlet side of the outdoor heat exchanger 4 when the outside air temperature is relatively low is determined, and the refrigerant temperature on the inlet side of the outdoor heat exchanger 4 is lower than a predetermined temperature (−10 ° C. in the present embodiment). If it is higher, the process proceeds to step S25, and if the refrigerant temperature on the inlet side of the outdoor heat exchanger 4 is -10 ° C or lower, it is determined that the heat exchange portion of the outdoor heat exchanger 4 is frosted. Then, the heating mode operation is stopped and the defrosting mode operation is started.

  After the defrosting mode operation is started in step S23, the inlet side refrigerant temperature of the outdoor heat exchanger 4 is checked in step S24, and the inlet side refrigerant temperature of the outdoor heat exchanger 4 is set to a predetermined temperature (7 in this embodiment). When the temperature is lower than (° C.), the process proceeds to step S23 and the defrosting operation is continued. When the refrigerant temperature on the inlet side of the outdoor heat exchanger 4 is 7 ° C. or higher, the process proceeds to step S25 (step S24).

  In step S25, it is determined whether or not the heating switch is turned on. If the heating switch is turned on, the process proceeds to step S10 to continue the heating mode operation, and if the heating switch is turned off, the heating mode operation is ended. .

  With the above configuration, in the heat pump air conditioner 1 of the present embodiment, the refrigerant inlet 4a of the outdoor heat exchanger 4 can be obtained by attaching the relatively inexpensive temperature sensor 17 to the refrigerant inlet 4a portion of the outdoor heat exchanger 4. Since the frosting state of the outdoor heat exchanger 4 is estimated from the refrigerant temperature at, the frosting state of the outdoor heat exchanger 4 can be determined at a relatively low cost without complicating the heat pump cycle.

  In addition, the refrigerant discharge amount of the compressor 2 changes according to the target indoor temperature, so that the refrigerant discharge amount can be increased and quickly adjusted to the target indoor temperature, and after reaching the target indoor temperature, the refrigerant discharge amount can be reduced. This can reduce the load on the compressor 2.

  In the heat pump type air conditioner of the present embodiment, the carbon dioxide gas as the refrigerant changes phase between the supercritical phase and the gas phase, but other substances are used as the refrigerant, and the liquid phase In the case where the present invention is applied to a heat pump type air conditioner configured to change between a gas phase and a gas phase, the present invention is not limited to this embodiment, and various other embodiments can be used without departing from the scope of the present invention. The same effect can be obtained.

  Further, the compressor 2 of the present embodiment is a constant capacity compressor, changing the rotational speed as required, increasing the rotational speed to increase the refrigerant discharge amount, and decreasing the rotational speed to reduce the refrigerant discharge amount. However, the same effect can be obtained even when the discharge amount of the refrigerant is changed without being affected by the rotation speed of the compressor using a variable displacement compressor.

The schematic diagram which shows the driving | running state in the air_conditioning | cooling mode of the heat pump type air conditioner in one Embodiment of this invention. The schematic diagram which shows the driving | running state in the heating mode of the heat pump type air conditioner in one Embodiment of this invention. The schematic diagram which shows the driving | running state in the dehumidification mode of the heat pump type air conditioner in one Embodiment of this invention. The schematic diagram which shows the driving | running state in the defrost mode of the heat pump type air conditioner in one Embodiment of this invention. Explanatory drawing which shows the flowchart which performs the defrost mode in one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Heat pump type air conditioner 2 ... Compressor 3 ... Indoor heat exchanger 4 ... Outdoor heat exchanger 4 ... This outdoor heat exchanger 4a ... Refrigerant inlet 13 ... Expansion valve 17 ... Temperature sensor

Claims (2)

A compressor (2) that pressurizes the refrigerant circulating in the pipe, and an indoor heat exchanger (3 ) that is disposed in the air conditioning duct (8) and transmits the heat of the refrigerant pressurized to the compressor (2) to the conditioned air. ), An expansion valve (13) for adiabatically expanding the refrigerant radiated by the indoor heat exchanger (3), an outdoor heat exchanger (4) for transferring the heat of outdoor air to the adiabatically expanded refrigerant, and the air conditioning duct ( 8) A heating passage (8a) through which the conditioned air passing through the air conditioning duct (8) passes through the indoor heat exchanger (3), and the conditioned air flows into the indoor heat exchanger (3). A heat pump air conditioner comprising a switching door (9) for switching between a bypass passage (8b) that bypasses
A temperature sensor (17) is provided at the refrigerant inlet (4a) of the outdoor heat exchanger (4),
When the frost formation state of the outdoor heat exchanger (4) is estimated from the refrigerant temperature detected by the temperature sensor (17) and it is determined that the frost formation state, the outdoor heat exchanger (4) Shift to defrost mode operation to remove frost that has arrived,
In the defrost mode, the refrigerant passes through the compressor (2) in the order of the indoor heat exchanger (3) and the outdoor heat exchanger (4) and returns to the compressor (2).
The heat pump air conditioner characterized in that the bypass passage (8b) is blocked by the switching door (9) and the conditioned air is passed through the heating passage (8a) . In the heat pump type air conditioner according to claim 1,
A heat pump air conditioner that detects at least a room temperature and changes a refrigerant discharge amount of the compressor (2) according to a target room temperature.

Images