DE112021004336T5 - refrigeration cycle device - Google Patents

Abstract

A refrigeration cycle device has a heating unit (12, 121, 50), a first expansion unit (13), an outdoor heat exchanging unit (14), a second expansion unit (16), and an indoor evaporating unit (17). The heating unit (12, 121, 50) heats a ventilation air. The first expansion unit (13) expands a refrigerant that flows out of the heating unit (12, 121, 50). The outdoor heat exchange unit (14) exchanges heat between the refrigerant flowing out of the first expansion unit (13) and an outside air. The second expansion unit (16) expands the refrigerant flowing out of the outdoor heat exchange unit (14). The indoor evaporating unit (17) cools the ventilation air before it is heated in the heating unit (12, 121, 50). The first expansion control unit (40b) controls an operation of the first expansion unit (13) so that a supercooling degree (SC1) of refrigerant flowing into the first expansion unit (13) is equal to or lower than a target supercooling degree (SCO). .

Description

Cross reference to related application

The registration is based on Japanese Patent Application No. 2020-139066 , filed August 20, 2020, the contents of which are incorporated herein by reference in their entirety.

field of invention

The present disclosure relates to a refrigeration cycle device and is suitable for use in an air conditioner that dehumidifies and heats a space to be air-conditioned.

State of the art

Conventionally, Patent Literature 1 discloses a refrigeration cycle device applied to a vehicle air conditioner configured to dehumidify and heat the inside of a vehicle cabin, which is a space to be air-conditioned.

The refrigeration cycle device of Patent Literature 1 includes a plurality of heat exchange units such as an indoor condenser, an outdoor heat exchanger, and an indoor evaporator. The indoor condenser is a heater unit that heats ventilation air to be blown into the vehicle cabin by using discharged refrigerant discharged from a compressor as a heat source. The refrigeration cycle device disclosed in Patent Literature 1 further includes a first expansion unit that expands the refrigerant that flows out of the indoor condenser, and a second expansion unit that expands the refrigerant that flows out of the outdoor heat exchanger.

In the refrigeration cycle device of Patent Literature 1, in a dehumidification-and-heating mode for dehumidifying and heating the inside of the vehicle cabin, a refrigerant cycle in which the three heat exchange units are serially connected in the following order from the upstream side of a refrigerant flow is switched: the indoor condenser, the outdoor heat exchanger and the indoor evaporator. In the vehicle air conditioner of Patent Literature 1, the ventilation air cooled and dehumidified in the indoor evaporator is reheated in the indoor condenser and blown into the vehicle cabin, thereby achieving the dehumidification and heating of the inside of the vehicle cabin.

Further, in the refrigeration cycle device of Patent Literature 1, a heating capacity of ventilation air in the indoor condenser in the dehumidification-and-heating mode is adjusted by changing a throttle opening degree of the first expansion unit and a throttle opening degree of the second expansion unit.

citation list

patent literature

Patent Literature 1: JP Patent No. 5585549

Summary of the Invention

In the refrigeration cycle device of Patent Literature 1, the throttle opening degree of the first expansion unit is changed to adjust the heating capacity of the ventilation air in the indoor condenser in the dehumidification-and-heating mode. For example, when the heating capacity of the ventilation air in the indoor condenser is increased, the throttle opening degree of the first expansion unit is decreased. Therefore, a degree of supercooling of the refrigerant on an outlet side of the indoor condenser increases more easily with increasing the heating capacity of the ventilation air in the indoor condenser.

However, if the degree of supercooling of the refrigerant on the outlet side of the indoor condenser becomes unnecessarily large, temperature non-uniformity occurs in ventilation air heated in the indoor condenser, and it is impossible to achieve comfortable dehumidification and warming of the inside of the vehicle cabin . If the degree of subcooling of the refrigerant on the outlet side of the indoor condenser becomes unnecessarily large, there is a possibility that a coefficient of performance (ie, a COP) of the cycle decreases.

In view of the above, an object of the present disclosure is to provide a refrigeration cycle device capable of appropriately adjusting a degree of supercooling of refrigerant on an outlet side of a heating unit.

To achieve the above object, a refrigeration cycle device according to a first aspect of the present disclosure includes a compressor, a heater unit, a first expansion unit, an outdoor heat exchange unit, a second expansion unit, an indoor evaporation unit, a target supercooling degree determination unit, a supercooling degree - Estimation unit and a first relaxation control unit.

The compressor is configured to compress and discharge refrigerant. The heating unit is configured to heat ventilation air to be blown into a space to be air-conditioned by using the refrigerant discharged from the compressor as a heat source. The first expansion unit is configured to expand the refrigerant that flows out of the heater unit. The outdoor heat exchange unit is configured to exchange heat between the refrigerant flowing out of the first expansion unit and outside air. The second expansion unit is configured to expand the refrigerant that flows out of the outdoor heat exchange unit. The indoor evaporating unit is configured to evaporate the refrigerant expanded in the second expansion unit to cool the ventilation air before it is heated in the heating unit. The target supercooling degree determination unit is configured to determine a target supercooling degree of refrigerant flowing into the first expansion unit. The supercooling degree estimating unit is configured to estimate a supercooling degree of the refrigerant flowing into the first expansion unit. The first relaxation control unit is configured to control an operation of the first relaxation unit.

Furthermore, the first relaxation control unit controls the operation of the first relaxation unit so that the degree of supercooling estimated by the degree of supercooling estimating unit is equal to or lower than the target degree of supercooling.

According to the present disclosure, the first relaxation control unit controls an operation of a first relaxation unit so that the supercooling degree is equal to or lower than the target supercooling degree. Therefore, it is possible to suppress an unnecessary increase in the degree of supercooling of the refrigerant that flows out of the heating unit and flows into the first expansion unit.

As a result, the refrigeration cycle device according to the first aspect is able to appropriately adjust the degree of supercooling of the refrigerant on the outlet side of the heater unit.

A refrigeration cycle device according to a second aspect of the present disclosure includes a compressor, a heater unit, a first expansion unit, an outdoor heat exchange unit, a second expansion unit, an indoor evaporation unit, a target supercooling degree determination unit, a lower interface calculation unit, and a first relaxation control unit.

The compressor is configured to compress and discharge the refrigerant. The heater unit is configured to heat ventilation air to be blown into a space to be air-conditioned by using the refrigerant discharged from the compressor as a heat source. The first expansion unit is configured to expand the refrigerant that flows out of the heater unit. The outdoor heat exchange unit is configured to exchange heat between the refrigerant flowing out of the first expansion unit and outside air. The second expansion unit is configured to expand the refrigerant that flows out of the outdoor heat exchange unit. The indoor evaporating unit is configured to evaporate the refrigerant expanded in the second expansion unit to cool the ventilation air before it is heated in the heating unit. The target supercooling degree determination unit is configured to determine a target supercooling degree of refrigerant flowing into the first expansion unit. The lower limit area calculation unit is configured to calculate a lower limit of a throttle passage area of the first expansion unit so that a degree of supercooling of the refrigerant flowing into the first expansion unit becomes equal to the target degree of supercooling. The first relaxation control unit is configured to control an operation of the first relaxation unit.

The first relaxation control unit controls the operation of the first relaxation unit so that a throttle passage area of the first relaxation unit is equal to or larger than the lower limit of a throttle passage area.

According to the present disclosure, the first relaxation control unit controls the operation of the first relaxation unit so that the throttle passage area of the first relaxation unit is equal to or larger than the lower limit of a throttle passage area. Thus, the degree of supercooling of the refrigerant flowing into the first expansion unit can be set equal to or lower than the target degree of supercooling. Therefore, it is possible to suppress an unnecessary increase in the degree of supercooling of the refrigerant that flows out of the heating unit and flows into the first expansion unit.

As a result, the refrigeration cycle device according to the second aspect is able to appropriately adjust the degree of supercooling of the refrigerant on the outlet side of the heater unit.

character list

• 1 14 is an overall configuration diagram of a vehicle air conditioner according to a first embodiment.
• 2 Fig. 12 is a block diagram showing an electric control unit of the vehicle air conditioner of the first embodiment.
• 3 Fig. 12 is a flow chart showing part of a control procedure of the vehicle air conditioner of the first embodiment.
• 4 FIG. 14 is a graph showing a relationship between a degree of supercooling and a density of a refrigerant.
• 5 14 is a Mollier chart showing a state change of refrigerant in a dehumidifying-and-heating mode of a refrigeration cycle device according to the first embodiment.
• 6 Fig. 14 is a flowchart showing part of a control flow of a vehicle air conditioner of a second embodiment.
• 7 14 is an overall configuration diagram of a vehicle air conditioner according to a third embodiment.
• 8th 14 is an overall configuration diagram of a vehicle air conditioner according to a fourth embodiment.
• 9 FIG. 14 is a graph showing temperature changes of a refrigerant and a heat medium in a medium/refrigerant heat exchanger.

Description of the embodiments

Hereinafter, a variety of embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, parts that correspond to items described in the previous embodiment are denoted by the same reference numerals, and redundant description may be omitted. In each embodiment, in a case where only part of the configuration is described, previously described other embodiments can be applied to the other part of the configuration. It is possible to combine not only parts expressly stated to be combinable in each embodiment but also partially to combine embodiments not expressly stated to be combinable as long as there is no problem in combining.

(First embodiment)

In relation to 1 until 5 A refrigeration cycle device 10 according to a first embodiment of the present disclosure will be described. The refrigeration cycle device 10 is applied to a vehicle air conditioner 1 shown in the overall configuration diagram of FIG 1 is shown. In the vehicle air conditioner 1, the refrigeration cycle device 10 adjusts a temperature of ventilation air to be blown into the inside of a vehicle cabin, which is a space to be air-conditioned. The vehicle air conditioner 1 includes the refrigeration cycle device 10, an indoor air conditioning unit 30, a control device 40, and the like.

The refrigeration cycle device 10 uses an HFO-based refrigerant (specifically, R1234yf) as a refrigerant. The refrigeration cycle device 10 forms a subcritical vapor compression refrigeration cycle in which a pressure of high-pressure refrigerant discharged from a compressor 11 does not exceed a critical pressure of the refrigerant. The refrigerant is mixed with a refrigerating machine oil (particularly, a PAG oil) to lubricate the compressor 11 . A part of the refrigerating machine oil circulates in the circuit together with the refrigerant.

The compressor 11 sucks, compresses, and discharges the refrigerant in the refrigeration cycle device 10 . The compressor 11 is arranged at the inside of a vehicle hood on the front side of the vehicle cabin, which is an auxiliary machine room. The compressor 11 is an electric compressor that rotationally drives a fixed stroke type compression mechanism with a fixed discharge capacity by an electric motor. A rotational speed of the compressor 11 (that is, a refrigerant discharge capacity) is controlled by a control signal output from the control device 40, which will be described later.

A refrigerant inlet side of the indoor condenser 12 is connected to a discharge port of the compressor 11 . The indoor condenser 12 is arranged in a case 31 of an indoor air conditioning unit 30, which will be described later. The indoor condenser 12 is a heat exchange unit that exchanges heat between the high-pressure refrigerant discharged from the compressor 11 and the ventilation air to dissipate heat of the high-pressure refrigerant to the ventilation air. Furthermore, the indoor condenser 12 is a heating unit that heats the ventilation air by using a discharged high-temperature, high-pressure refrigerant discharged from the compressor 11 as a heat source.

An inlet side of the heater expansion valve 13 is connected to a refrigerant outlet of the indoor condenser 12 . The heater expansion valve 13 is a first expansion unit that expands refrigerant flowing out of the indoor condenser 12 .

The heater expansion valve 13 is an electric variable throttle mechanism that includes a valve body portion that changes an opening degree of a throttle passage (that is, a valve opening degree) and an electric actuator (specifically, a stepping motor) that displaces the valve body portion. An operation of the heater expansion valve 13 is controlled by a control signal (specifically, a control pulse) output from the control device 40 .

The heater expansion valve 13 has a full open function. In the full-open function, the valve body portion adjusts the valve opening degree to a full-open degree, and the heater expansion valve 13 therefore functions only as a refrigerant passage almost without exerting any flow rate adjustment action or refrigerant pressure reducing action.

A refrigerant inlet side of an outdoor heat exchanger 14 is connected to an outlet of the heater expansion valve 13 . The outdoor heat exchanger 14 is an outdoor heat exchange unit that exchanges heat between the refrigerant flowing out from the heater expansion valve 13 and outdoor air blown by an outdoor air fan (not shown). The outdoor heat exchanger 14 is arranged on the front side at the vehicle hood. Therefore, when the vehicle is running, a running wind flowing into the vehicle hood through a grille can be blown against the outdoor heat exchanger 14 .

An inlet side of a header 15 is connected to a refrigerant outlet of the outdoor heat exchanger 14 . The accumulator 15 is a liquid reservoir on a high-pressure side that has a gas-liquid separating function. The accumulator 15 separates a gas and a liquid of the refrigerant that flows out of the heat exchange unit that functions as a condenser for condensing the refrigerant in the refrigeration cycle device 10 . The accumulator 15 further causes a part of the separated liquid-phase refrigerant to flow out to the downstream side, and stores a remaining liquid-phase refrigerant as a surplus refrigerant of the cycle.

An inlet side of a refrigeration expansion valve 16 is connected to an outlet of the accumulator 15 . The refrigeration expansion valve 16 is a second expansion unit that expands the refrigerant flowing out of the accumulator 15 . The cooling expansion valve 16 has a basic configuration similar to that of the heating expansion valve 13 .

A refrigerant inlet side of an indoor evaporator 17 is connected to an outlet of the refrigeration expansion valve 16 . The indoor evaporator 17 is arranged in the case 31 of the indoor air conditioning unit 30 . The indoor evaporator 17 is a heat exchange unit that exchanges heat between a low-pressure refrigerant expanded by the refrigeration expansion valve 16 and the ventilation air supplied from the indoor fan 32 to evaporate the refrigerant. Furthermore, the indoor evaporator 17 is an indoor evaporating unit that cools the ventilation air by evaporating the low-pressure refrigerant to exert a heat absorbing action. A suction port side of the compressor 11 is connected to a refrigerant outlet of the indoor evaporator 17 .

Next, the indoor air conditioning unit 30 will be described. The indoor air conditioning unit 30 is a unit in which various constituent devices are integrated in the vehicle air conditioner 1 to blow the ventilation air whose temperature has been appropriately adjusted to an appropriate position in the vehicle cabin. The indoor air conditioning unit 30 is arranged inside an instrument panel (that is, the instrument panel) at the very front of the vehicle cabin.

The indoor air conditioning unit 30 includes the case 31 forming an air passage for the ventilation air. The indoor fan 32, the indoor evaporator 17, the indoor condenser 12 and the like are arranged in the air passage formed in the case 31. As shown in FIG. The case 31 is made of a resin (e.g. polypropylene) which has a certain degree of elasticity and excellent strength.

An inside air and outside air switching device 33 is arranged on the most upstream side of the case 31 in a ventilation air flow direction. The inside air and outside air switching device 33 introduces inside air (that is, air inside the vehicle cabin) or outside air (that is, air outside the vehicle cabin) into the case 31 by switching therebetween. An operation of an electric actuator for driving the inside and outside air switching device 33 is controlled by a control signal output from the control device 40 .

An indoor fan 32 is arranged on the downstream side of the indoor air and outdoor air switching device 33 with respect to the ventilation air flow. The indoor blower 32 is an air blower unit that blows air drawn by the inside and outside air switching device 33 toward the inside of the vehicle cabin. The indoor fan 32 is an electric fan in which a multi-blade centrifugal fan is driven by an electric motor. A rotation speed of the indoor blower 32 (that is, an air blowing capacity) is controlled by a control voltage output from the control device 40 .

On the downstream side of the indoor fan 32 with respect to the ventilation air flow, the indoor evaporator 17 and the indoor condenser 12 are arranged in order from the upstream side with respect to the ventilation air flow. In other words, the indoor evaporator 17 is arranged on the upstream side of the indoor condenser 12 with respect to the ventilation air flow. In the casing 31, a cold air bypass passage 35 is formed, which allows the ventilation air that has passed through the indoor evaporator 17 to flow to the downstream side while the indoor condenser 12 is bypassed.

An air mix door 34 is arranged on the downstream side of the indoor evaporator 17 with respect to the ventilation air flow and on an upstream side of the indoor condenser 12 with respect to the ventilation air flow. The air mix door 34 adjusts an air volume ratio between an air volume of the ventilation air passing through the indoor condenser 12 and an air volume of the ventilation air passing through the cold air bypass passage 35 . An operation of an electric actuator for driving the air mix door 34 is controlled by a control signal output from the controller 40 .

On the downstream side of the indoor condenser 12 with respect to the ventilation air flow, there is a mixing space 36 for mixing the ventilation air heated in the indoor condenser 12 and the ventilation air that has passed through the cold air bypass passage 35 and not in the indoor Capacitor 12 is heated, provided. Further, in the most downstream part of the case 31 in the ventilation air flow, opening holes (not shown) through which the ventilation air (an air conditioning air) mixed in the mixing space 36 is blown into the vehicle cabin are provided.

Therefore, a temperature of the conditioning air mixed in the mixing space 36 can be adjusted by adjusting the air volume ratio between the volume of air caused by the air mix door 34 to pass through the indoor condenser 12 and the volume of air caused by the air mix door 34 to pass through the cold air bypass passage 35 is adjusted. Thus, the temperature of ventilation air blown into the vehicle cabin from the opening holes can be adjusted.

As the opening holes, a face opening hole, a foot opening hole, and a defrost opening hole (all not shown) are provided. The face opening hole is an opening hole for blowing the conditioning air toward an occupant's upper body in the vehicle cabin. The foot opening hole is an opening hole for blowing the conditioning air to the occupant's feet. The defrost opening hole is an opening hole through which air conditioning air is blown to an inner surface of a windshield of the vehicle.

Blowing mode switching doors (not shown) are arranged on upstream sides of the opening holes. By opening and closing the respective opening holes, the blow mode switching doors switch the opening holes through which conditioning air is blown out. An operation of electric actuators for driving the blow mode switching doors is controlled by a control signal output from the controller 40 .

Next, an overview of the electric control unit of the vehicle air conditioner 1 will be given with reference to FIG 2 described. The control device 40 is configured with: a known microcomputer having a CPU, ROM, RAM and the like; and a surrounding circuit of the microcomputer. The control device 40 performs various calculations and processing based on a control program stored in the ROM, and controls the operation of the various control target devices 11, 13, 16, 32, 33, 34 and the like associated with an output side of the control device 40 are connected.

As in 2 As illustrated, various sensors used for air conditioning control are connected to an input side of the control device 40 . The various sensors include an inside air temperature sensor 41a, an outside air temperature sensor 41b, a solar radiation amount sensor 41c, a high pressure temperature sensor 41d, a high pressure sensor 41e, a low pressure temperature sensor 41f, a low pressure sensor 41g and a conditioning air temperature sensor 41h.

The inside air temperature sensor 41a is an inside air temperature detector that detects an inside air temperature Tr, which is a temperature in the vehicle cabin. The outside air temperature sensor 41b is an outside air temperature detector that detects an outside air temperature Tam, which is a temperature outside the vehicle cabin. The solar radiation amount sensor 41c is solar radiation amount detection means that detects an amount As of solar radiation irradiated to the inside of the vehicle cabin.

The high-pressure temperature sensor 41 d is a high-pressure temperature detector that detects a discharge temperature Td of the discharged refrigerant discharged from the compressor 11 . The high pressure sensor 41 e is high pressure detection means that detects a discharge pressure Pd of the discharged refrigerant discharged from the compressor 11 .

The high-pressure temperature sensor 41d and the high-pressure sensor 41e are also used to detect an abnormal increase in the discharge temperature Td or the discharge pressure Pd. Upon detecting an abnormal increase in the discharge temperature Td or the discharge pressure Pd, the control device 40 performs compressor protection control for protecting the compressor 11 by stopping the compressor 11 .

A low-pressure temperature sensor 41 f is a low-pressure temperature detector that detects a suction temperature Ts of the suction refrigerant to be sucked into the compressor 11 . The low-pressure sensor 41 g is low-pressure detection means that detects a suction pressure Ps of the suction refrigerant to be sucked into the compressor 11 .

Specifically, the low-pressure temperature sensor 41 f of the present embodiment detects a temperature of an outer surface of a refrigerant pipe extending from the refrigerant outlet of the indoor evaporator 17 to the suction port of the compressor 11 . As the low-pressure temperature sensor, an evaporator temperature detector to detect an evaporator temperature Tefin, which is a temperature of a heat exchange fin of the indoor evaporator 17, may be employed.

The conditioning air temperature sensor 41h is conditioning air temperature detection means that detects a blown air temperature TAV of blown air blown from the mixing space 36 into the vehicle cabin.

Further, to the input side of the control device 40, a control panel 42 is connected, which is arranged near the instrument panel at the very front on the inside of the vehicle cabin, and operation signals from various operation switches provided on the control panel 42 are input to the control device 40. Specific examples of the various operation switches provided on the control panel 42 include an auto switch, an air conditioner switch, an air volume adjustment switch, and a temperature adjustment switch.

The automatic switch is an automatic control requesting unit for an occupant to request that an automatic control operation of the vehicle air conditioner 1 be set or released. The air conditioning switch is a cooling request unit for the occupant to request the indoor evaporator 17 to cool the ventilation air. The air volume adjustment switch is an air volume adjustment unit for the occupant to adjust an air volume of the indoor blower 32 manually. The temperature setting switch is a temperature setting unit for the occupant to set a target temperature Tset in the vehicle cabin.

Moreover, the control device 40 of the present embodiment is configured integrally with a control unit that controls various control target devices connected to the output side of the control device 40 . Therefore, a configuration for controlling the operation of each control target device (that is, hardware and software) constitutes a control unit for controlling the operation of each control target device.

For example, in the control device 40, a configuration that controls the rotation speed of the compressor 11 is a compressor control unit 40a. In the control device 40, a configuration that controls the operation of the heater expansion valve 13 is a first expansion control unit 40b. In the control device 40, a configuration that controls the operation of the refrigeration expansion valve 16 is a second expansion control unit 40c.

Next, a description will be given about an operation of the vehicle air conditioner 1 of the present embodiment having the above configuration. In the vehicle air conditioner 1, an operation mode for appropriately air-conditioning the vehicle cabin is switched. in particular Alternatively, the vehicle air conditioner 1 can be switched between a cooling mode and the dehumidifying-and-heating mode. Operation mode switching is performed by executing a control program stored in the control device 40 .

The control program starts to be executed when the automatic switch is turned on in a state where the air conditioner switch on the control panel 42 is turned on. In the control program, the operation mode is determined based on a target blowout temperature TAO, detection signals from the various sensors, and an operation signal from the control panel 42 . The target blow-out temperature TAO is a target temperature of ventilation air that is blown into the vehicle cabin.

The target blowout temperature TAO is calculated by the following formula F1. $$\text{TAO}=\text{cheese}\times \text{Tset}-\text{kr}\times \text{Tr}-\text{Came}\times \text{tam}-\text{Ks}\times \text{ace}+\text{C}$$

Tset is a setting temperature inside the vehicle cabin set by the temperature setting switch. Tr is a vehicle cabin inside temperature detected by the inside air sensor. Tam is the temperature outside the vehicle cabin detected by the outside air sensor. As is the amount of solar radiation detected by the solar radiation sensor. Kset, Kr, Kam and Ks are control gains and C is a correction constant.

Further, in the control program, control states of the various control target devices are determined in accordance with the determined operation mode. Then, the control device 40 outputs control signals or control voltages to the various control target devices to achieve the control state determined by the control program.

In every predetermined control cycle, until the vehicle air conditioner 1 is requested to stop, the control program repeats a control routine including: reading out detection signals and operation signals; calculating the target outlet temperature TAO; determining the control states of the various control target devices; outputting control signals to the various control target devices; and similar. Each operating mode is described below.

(a) Cooling mode

In the cooling mode, the control states of the various control target devices are determined as described below. The refrigerant discharge capacity of the compressor 11 is determined so that the suction temperature Ts detected by the low-pressure temperature sensor 41f becomes close to the target evaporator temperature TEO. The target evaporator temperature TEO is determined based on the target blowout temperature TAO with reference to a control map stored in the control device 40 in advance.

According to the control map, the target evaporator temperature TEO is decreased as the target blowout temperature TAO is decreased. The target evaporator temperature TEO is determined to be a value within such a range that the indoor evaporator 17 does not freeze.

For the heater expansion valve 13, the control state is determined so that the heater expansion valve 13 is in a fully open state. For the refrigeration expansion valve 16, the throttle opening degree is determined so that a superheat degree SH of the refrigerant on the outlet side of the indoor evaporator 17 becomes close to a predetermined reference superheat degree KSH (3°C in the present embodiment). The degree of superheat SH is calculated using the suction temperature Ts detected by the low-pressure temperature sensor 41f and the suction pressure Ps detected by the low-pressure sensor 41g.

For the indoor blower 32, the blowing capacity thereof is determined based on the target blow-out temperature TAO with reference to a control map stored in the control device 40 in advance. According to the control map, the air-blowing capacity is determined such that when the target blow-out temperature TAO is in an extremely low temperature range or an extremely high temperature range, the air-blowing amount is at its maximum, so that when the target blow-out temperature TAO is closer to a middle one temperature range becomes, the air blowing amount becomes gradually smaller.

For the electric actuator for the air mix door, the control state is determined such that an air passage on the indoor condenser 12 side is fully closed and the cold air bypass passage 35 is fully opened. In the cooling mode, the opening degree of the air mix door 34 can be determined so that the blown air temperature TAV by the Conditioning air temperature sensor 41h becomes close to the target blowout temperature TAO.

Therefore, in the refrigeration cycle device 10 in the cooling mode, the discharged refrigerant discharged from the compressor 11 flows into the indoor condenser 12. In the cooling mode, since the air mix door 34 has closed the air passage on the indoor condenser 12 side, it flows Refrigerant that has flowed into the indoor condenser 12 out of the indoor condenser 12 almost without exchanging heat with the ventilation air.

The refrigerant that has flowed out of the indoor condenser 12 flows into the outdoor heat exchanger 14 via the fully opened heating expansion valve 13. The refrigerant that has flowed into the outdoor heat exchanger 14 dissipates heat to the outdoor air and thereby condenses . The refrigerant flowing out of the outdoor heat exchanger 14 flows into the receiver 15 and is separated into a gas and a liquid.

A liquid-phase refrigerant flowing out of the accumulator 15 flows into the refrigeration expansion valve 16 and is expanded. At this time, the throttle opening degree of the refrigeration expansion valve 16 is determined so that the superheat degree SH of the refrigerant on the outlet side of the indoor evaporator 17 becomes close to the reference superheat degree KSH. The refrigerant expanded by the refrigeration expansion valve 16 flows into the indoor evaporator 17.

The refrigerant that has flowed into the indoor evaporator 17 absorbs heat from the ventilation air and thereby evaporates. The ventilation air is thus cooled. The refrigerant flowing out of the indoor evaporator 17 is drawn into the compressor 11 and compressed again.

With the indoor air conditioning unit 30 in the cooling mode, the ventilation air cooled by the indoor evaporator 17 is blown into the vehicle cabin. As a result, cooling of the vehicle cabin is achieved.

(b) dehumidification-and-heating mode

In the dehumidification-and-heating mode, control states of various control target devices are determined as follows. For the compressor 11 and the indoor fan 32, the control states are determined in a manner similar to the cooling mode.

The throttle opening degree of the heater expansion valve 13 is determined by following a control flow shown in FIG 3 shown is executed. The control flow that 3 is executed as a subroutine of a main routine of the control program. The control steps shown in the flowcharts of 3 and the like are each a function implementation unit included in the control device 40 .

First, at step S1 of 3 the target subcooling degree SCO of the refrigerant flowing out of the indoor condenser 12 and flowing into the heater expansion valve 13, that is, the target subcooling degree SCO of the refrigerant on the outlet side of the indoor condenser 13 is determined. Therefore, step S1 is a target supercooling degree determination unit.

Specifically, at step S<b>1 , the target supercooling degree SCO is determined with reference to the control map previously stored in the control device 40 based on an inlet-side pressure P<b>1 of refrigerant flowing into the heater expansion valve 13 . According to the control map, the target supercooling degree SCO is determined so that a coefficient of performance (ie, a COP) of the cycle is a maximum value.

As the inlet-side pressure P1, a value obtained by subtracting a pressure loss generated when the refrigerant passes through the indoor condenser 12 from the discharge pressure Pd detected by the high-pressure sensor 41e can be used . In the present embodiment, since a ratio of the pressure loss to the discharge pressure Pd is comparatively small, the discharge pressure Pd is employed as the inlet-side pressure P1.

Next, at step S2, a degree of supercooling SC1 of refrigerant flowing out of the indoor condenser 12 and flowing into the heater expansion valve 13 is estimated. Therefore, step S2 is a supercooling degree estimating unit. At step S2, the degree of supercooling SC1 is estimated using a refrigerant discharge flow rate Gr (mass flow rate) of the compressor 11, the throttle passage area A of the heater expansion valve 13, the discharge pressure Pd, and the outside air temperature Tam.

The refrigerant discharge flow rate Gr of the compressor 11 can be calculated from a suction density pcin of a suction refrigerant to be sucked into the compressor 11, the rotational speed of the compressor 11, the discharge capacity of the compressor 11, and the volumetric efficiency of the compressor 11.

The suction density pcin can be determined from the suction temperature Ts and the suction pressure Ps based on the physical properties of the refrigerant. The rotational speed of the compressor 11 can be determined from a control signal that is output from the controller 40 to the compressor 11 . A discharge capacity of the compressor 11 and a volumetric efficiency of the compressor 11 can be obtained from a specification of the compressor 11, test data, and the like.

The orifice area A of the heater expansion valve 13 can be determined based on a specification of the heater expansion valve 13 and a control signal (specifically, a control pulse) that is output from the control device 40 to the heater expansion valve 13 .

The discharge pressure Pd is used to determine the inlet-side pressure P1 in a similar manner to the target supercooling degree determination unit.

The outside air temperature Tam is used to determine the outlet-side pressure P2 of the refrigerant that flows out of the heater expansion valve 13 . The outlet-side pressure P2 is equal to a saturation pressure of the refrigerant in the outdoor heat exchanger 14 connected to the outlet side of the heating expansion valve 13, and the temperature of the refrigerant in the outdoor heat exchanger 14 is substantially equal to the outside air temperature Tam the saturation pressure of the refrigerant at the outside air temperature Tam can be substituted as the outlet-side pressure P2.

At step S2, an inlet-side density pin of the refrigerant flowing into the heater expansion valve 13 is calculated using the following formula F2. $$\mathrm{\rho }\text{in}=G\mathrm{right}2/(2\times \left(\text{<figure-callout id="1" label="P" filenames="DE112021004336T5\_0014.png" state="{{state}}">P</figure-callout>}1-\text{P}2\right)\times \text{A}2)$$

The inlet side density pin and the degree of supercooling SC1 have a correlation as in 4 is shown. Therefore, the degree of supercooling SC1 can be estimated by calculating the inlet-side density pin by the formula F2.

Next, at step S3, it is determined whether the supercooling degree SC1 estimated at step S2 is larger than the target supercooling degree SCO determined at step S1. Therefore, step S3 is a supercooling degree determination unit that determines whether the supercooling degree SC1 is larger than the target supercooling degree SCO.

If it is determined in step S3 that the supercooling degree SC1 is not greater than the target supercooling degree SCO, that is, if the supercooling degree SC1 is equal to or smaller than the target supercooling degree SCO, the process proceeds to step S4. On the other hand, if it is determined in step S3 that the supercooling degree SC1 is greater than the target supercooling degree SCO, the process proceeds to step S5.

At step S4, blow-out temperature control is performed and the process returns to the main routine. In the blowout temperature control, the throttle opening degree of the heater expansion valve 13 is controlled so that the blown air temperature TAV becomes close to the target blowout temperature TAO.

Specifically, when the blown air temperature TAV is lower than the target blow-out temperature TAO, the throttle opening degree of the heater expansion valve 13 is reduced in such a range that the temperature of refrigerant flowing into the outdoor heat exchanger 14 is higher than the outdoor air temperature Tam. When the blown air temperature TAV is higher than the target blow-out temperature TAO, the throttle opening degree of the heater expansion valve 13 is increased.

As a result, in the blowout temperature control, it is possible to adjust an amount of heat dissipation from the refrigerant to the ventilation air in the indoor condenser 12, that is, to adjust the heating capacity of the ventilation air in the indoor condenser 12 by adjusting an amount of heat exchange between the refrigerant and the outdoor air in the outdoor heat exchanger 14 is adjusted.

At step S5, the throttle opening degree of the heater expansion valve 13 is increased by a predetermined amount, and the process returns to the main routine. The degree of supercooling SC1 of the refrigerant flowing out of the indoor condenser 12 and flowing into the heater expansion valve 13, that is, the degree of supercooling SC1 of the refrigerant on the outlet side of the indoor condenser 12 is lowered.

In the dehumidification-and-heating mode, the throttle opening degree of the cooling expansion valve 16 is controlled in a manner similar to that in the cooling mode. In the dehumidification-and-heating mode, the throttle opening degree of the cooling expansion valve 16 is larger than that in the cooling mode because the heating expansion valve 13 is in such a throttling state that a refrigerant expansion action is exerted.

In the dehumidification-and-heating mode, for the air mix door electric actuator, the control state is determined such that the air passage on the indoor condenser 12 side is fully opened and the cold air bypass passage 35 is fully closed. For the opening degree of the air mix door 34, in a manner similar to that in the cooling mode, the control state can be determined so that the blown air temperature TAV becomes close to the target blowout temperature TAO.

Therefore, in the refrigeration cycle device 10, as shown in the Mollier diagram in FIG 5 shown, the discharged refrigerant discharged from the compressor 11 (point a5 in 5 ) into the indoor condenser 12. In the dehumidifying-and-heating mode, the refrigerant that has flowed into the indoor condenser 12 dissipates heat to the ventilation air that has passed through the indoor evaporator 17 and thereby condenses (from point a5 to point b5 in 5 ) since the air passage on the indoor condenser 12 side is opened by the air mix door 34 . As a result, the ventilation air that has passed through the indoor evaporator 17 is heated.

The refrigerant that flows out of the indoor condenser 12 flows into the heater expansion valve 13 and is expanded (from point b5 to point c5 in 5 ). At this time, the throttle opening degree of the heater expansion valve 13 is adjusted so that at least the supercooling degree SC1 of the refrigerant that flows out of the indoor condenser 12 and flows into the heater expansion valve 13 (point b5 in Fig 5 ) is equal to or lower than the target subcooling degree SCO.

The throttle opening degree of the heater expansion valve 13 is further adjusted so that in a range in which the supercooling degree SC1 of the refrigerant flowing out of the indoor condenser 12 and flowing into the heater expansion valve 13 is equal to or lower than the target supercooling degree SCO, the blown air temperature TAV becomes close to the target blown air temperature TAO. The refrigerant expanded by the heater expansion valve 13 flows into the outdoor heat exchanger 14. The refrigerant that has flowed into the outdoor heat exchanger 14 dissipates heat to the outdoor air and thereby condenses (from point c5 to point d5 in 5 ).

The refrigerant flowing out of the outdoor heat exchanger 14 flows into the receiver 15 and is separated into a gas and a liquid. The liquid-phase refrigerant flowing out of the receiver 15 (point d5 in 5 ) flows into the refrigeration expansion valve 16 and is expanded (from point d5 to point e5 in 5 ). At this time, the throttle opening degree of the refrigeration expansion valve 16 is determined so that the superheat degree SH of the refrigerant (point f5 in 5 ) at the outlet side of the indoor evaporator 17 becomes close to the reference superheat degree KSH. The refrigerant expanded by the refrigeration expansion valve 16 flows into the indoor evaporator 17.

The refrigerant that has flowed into the indoor evaporator 17 absorbs heat from the ventilation air and thereby evaporates (from point e5 to point f5 in 5 ). As a result, the ventilation air is cooled and dehumidified. The refrigerant flowing out of the indoor evaporator 17 is sucked into the compressor 11 and compressed again (from point f5 to point a5 in 5 ).

With the indoor air conditioning unit 30 in the dehumidification-and-heating mode, the ventilation air cooled and dehumidified in the indoor evaporator 17 is reheated in the indoor condenser 12 and blown into the vehicle cabin. As a result, dehumidifying and heating of the inside of the vehicle cabin is achieved.

As described above, the vehicle air conditioner 1 of the present embodiment can achieve cooling and moreover dehumidification and heating of the inside of the vehicle cabin.

In the dehumidification-and-heating mode, the refrigeration cycle device 10 performs blow-out temperature control in which the throttle opening degree of the heating expansion valve 13 is changed to adjust the heating capacity of the ventilation air in the indoor condenser 12 . In the blowout temperature control, the throttle opening degree of the heater expansion valve 13 is decreased to increase the heating capacity of the ventilation air in the indoor condenser 12 . In addition, when the heating ability of the indoor condenser 12 is increased, the degree of supercooling SC1 easily increases correspondingly.

However, if the degree of supercooling SC1 is unnecessarily increased, temperature non-uniformity occurs in the ventilation air heated in the indoor condenser 12, and it sometimes becomes impossible to achieve comfortable dehumidification and heating of the inside of the vehicle cabin. Further, if the supercooling degree SC1 greatly exceeds the target supercooling degree SCO, the COP decreases accordingly.

On the other hand, in the refrigeration cycle device 10 of the present embodiment, in the dehumidification-and-heating mode, the throttle opening The degree of cooling of the heating expansion valve 13 is controlled so that the degree of supercooling SC1 estimated at step S2 is equal to or lower than the target degree of supercooling SCO determined at step S1. Therefore, it is possible to suppress an unnecessary increase in the supercooling degree SC<b>1 of the refrigerant that flows out of the indoor condenser 12 and flows into the heater expansion valve 13 .

That is, with the refrigeration cycle device 10 of the present embodiment, it is possible to appropriately adjust the supercooling degree SC1 of the refrigerant on the outlet side of the indoor condenser 12, which is the heating unit. As a result, comfortable dehumidification and warming of the inside of the vehicle cabin can be achieved, and a decrease in COP can be suppressed.

The supercooling degree estimating unit according to the present embodiment estimates the supercooling degree SC1 using the refrigerant discharge flow rate Gr of the compressor 11, the throttle passage area A of the heater expansion valve 13, the inlet-side pressure P1, and the outside air temperature Tam. Therefore, the degree of supercooling SC1 can be accurately determined as described in relation to Formula F2.

Furthermore, the parameters used to estimate the degree of supercooling SC1 can be detected by detectors essential to the blowout temperature control and the compressor protection control. Therefore, in the supercooling degree estimating unit of the present embodiment, there is no need to add a new detector to estimate the supercooling degree SC1.

Further, in the supercooling degree estimating unit of the present embodiment, the supercooling degree SC1 is estimated; therefore, even when the refrigerant that actually flows into the heating expansion valve 13 is in a gas-liquid two-phase state having a degree of dryness, the operation in the dehumidifying-and-heating mode can be continued.

(Second embodiment)

In the present embodiment, a description will be given on an example in which a control form of the heating expansion valve 13 in the dehumidifying-and-heating mode is modified from that in the first embodiment as shown in the flowchart of FIG 6 is shown.

Specifically, at step S11 of 6 the target supercooling degree SCO is determined in a manner similar to the first embodiment. Therefore, step S11 is a target supercooling degree determination unit.

Next, at step S12, the lower limit of a throttle passage area Amin of the heater expansion valve 13 is calculated. The lower limit of the orifice passage area Amin is such an orifice passage area of the heater expansion valve 13 that the supercooling degree SC1 of the refrigerant flowing into the heater expansion valve 13 is equal to the target supercooling degree SCO. Therefore, step S12 is a lower boundary surface calculation unit.

Specifically, at step S12, in a lower limit throttle passage area Amin calculation, the minimum throttle passage area Amin is calculated using the target supercooling degree SCO, the refrigerant discharge flow rate Gr of the compressor 11, the discharge pressure Pd, and the outside air temperature Tam. The refrigerant discharge flow rate Gr of the compressor 11 can be obtained in a manner similar to the first embodiment. The discharge pressure Pd is used to determine the inlet-side pressure P1 in a manner similar to the first embodiment. The outside air temperature Tam is used to determine the outlet-side pressure P2 in a manner similar to the first embodiment.

At step S12, the lower limit of a throttle passage area Amin is calculated by the following formula F3. $$\text{amine}=\text{size}/\mathrm{\rho }\text{Max}\times (\mathrm{\rho }\text{Max}/(2\times \left(\text{<figure-callout id="1" label="P" filenames="DE112021004336T5\_0014.png" state="{{state}}">P</figure-callout>}1-\text{P}2\right)))1/2$$

Note that pmax is an inlet-side density of the refrigerant flowing into the heater expansion valve 13 at the target superheat degree SCO. pmax can be determined by 4 is used, which is described in the first embodiment.

Note that Formula F3 is a formula obtained by modifying Formula F2 described in the first embodiment. That is, the lower limit area calculation unit calculates the lower limit of an orifice passage area Amin by using a formula that is equivalent to the formula used in the supercooling degree determination unit of the first embodiment.

Next, at step S13, it is determined whether the actual throttle passage area A of the heater expansion valve 13 is smaller than the lower limit of a throttle passage area Amin determined at step S12. Therefore, step S13 is a throttle passage area determination unit that determines whether the throttle passage area A is smaller than the lower limit of a throttle passage area Amin.

If it is determined at step S13 that the throttle passage area A is not smaller than the lower limit of a throttle passage area Amin, that is, if it is determined that the throttle passage area A is equal to or larger than the lower limit of a throttle passage area Amin, the process proceeds to Step S14. On the other hand, if it is determined at step S13 that the throttle passage area A is smaller than the lower limit of a throttle passage area Amin, the process proceeds to step S15.

At step S14, in a manner similar to step S4 of the first embodiment, the blowout temperature control is processed and the process returns to the main routine. At step S15, in a manner similar to step S5 of the first embodiment, the throttle opening degree of the heater expansion valve 13 is increased by a predetermined amount and the process returns to the main routine.

The other configurations and operations of the refrigeration cycle device 10 and the vehicle air conditioner 1 are similar to those of the first embodiment. Therefore, the vehicle air conditioner 1 according to the present embodiment can also achieve cooling and dehumidification and heating of the inside of the vehicle cabin in a manner similar to the first embodiment.

In the refrigeration cycle device 10 according to the present embodiment, the throttle opening degree of the heater-expansion valve 13 is controlled so that the throttle passage area A is equal to or larger than the lower limit of a throttle passage area Amin in the dehumidification-and-heating mode. This control allows the supercooling degree SC1 to be equal to or lower than the target supercooling degree SCO. Therefore, it is possible to obtain the same effects as the first embodiment.

That is, also in the refrigeration cycle device 10 of the present embodiment, it is possible to appropriately adjust the degree of supercooling SC1 and the refrigerant on the outlet side of the indoor condenser 12, which is the heating unit.

(Third embodiment)

In the vehicle air conditioner 1 of the present embodiment, compared to the first embodiment, an electric heater 37 is arranged on a downstream side of the indoor condenser 12 in the indoor air conditioning unit 30 with respect to the ventilation air flow as in the overall configuration diagram of FIG 7 is shown.

The electric heater 37 is an auxiliary heating unit that auxiliaryly heats the ventilation air when the blown air temperature TAV of the ventilation air cannot be raised to the target blowout temperature TAO solely by the heating capacity of the refrigeration cycle device 10 in the dehumidifying-and-heating mode. As the electric heater 37, it is possible to employ a positive temperature coefficient (PTC) heater or the like that generates heat by being energized. A calorific value of the electric heater 37 is controlled by a control voltage output from the control device 40 .

Further, a suction temperature sensor 41i as a sensor used for air conditioning control is connected to the input side of the control device 40 of the present embodiment. The suction temperature sensor 41i is suction temperature detection means that detects a suction air temperature Tin of suction air flowing into the indoor evaporator 17 via the inside and outside air switching device 33 .

The supercooling degree estimating unit of the present embodiment estimates the supercooling degree SC1 by using the refrigerant discharge flow rate Gr of the compressor 11, the discharge temperature Td, the discharge pressure Pd, an air blowing amount Airf (a mass flow rate) of the indoor fan 32, the suction air temperature Tein and a heating amount Qh of the electric Heater 37 can be used.

The refrigerant discharge flow rate Gr of the compressor 11 can be calculated in a manner similar to the first embodiment. The air-blowing amount Airf of the indoor fan 32 can be determined from a specification of the indoor fan 32 and a control voltage that is output from the control device 40 to the indoor fan 32 . The amount of heating Qh of the electric heater 37 can be determined based on a specification of the electric heater 37 and an amount of current supplied from the control device 40 to the electric heater 37 .

$$\text{Qc}=\mathrm{\rho }\text{ain}\times \text{Airfc}\times \text{Cair}\times \left(\text{TAV}-\text{Tein}\right)$$

$$\text{Qex}=\text{Gr}\times \left(\text{Hcin}-\text{Hcout}\right)$$

Hier ist Qc ein gesamter Erwärmungsbetrag (das heißt, der gesamte Wärmeaufnahmebetrag der Lüftungsluft) der Lüftungsluft. Qex ist ein Betrag einer Wärmeableitung von dem Kältemittel, das in dem Innen-Kondensator 12 kondensiert wird, zu der Lüftungsluft.The supercooling degree estimating unit of the present embodiment calculates a discharge-side enthalpy Hcout of the refrigerant on the outlet side of the indoor condenser 12 based on the following formulas F4 to F6. $$\text{qc}=\text{Qex}+\text{uh}$$

$$\text{qc}=\mathrm{\rho }\text{no}\times \text{Airfc}\times \text{cair}\times \left(\text{TAV}-\text{thein}\right)$$

$$\text{Qex}=\text{size}\times \left(\text{Hcin}-\text{hcout}\right)$$

Here, Qc is a total heating amount (that is, total heat absorption amount of ventilation air) of ventilation air. Qex is an amount of heat dissipation from the refrigerant condensed in the indoor condenser 12 to the ventilation air.

pair is the density of the suction air. In the present embodiment, a density of air in a predetermined reference condition (for example, 25°C, 101.3 kPa) is employed as the density of suction air. Furthermore, Cair is a specific heat of the air in the reference state.

Airfc is an indoor condenser-side air volume of ventilation air passing through the indoor condenser 12 . In the dehumidification-and-heating mode of the present embodiment, since the air mix door 34 completely closes the cold air bypass passage 35, the indoor condenser-side air volume Airfc is equal to the air-blowing amount Airf. When the cool air bypass passage 35 is opened by the air mix door 34 , the indoor condenser-side air volume Airfc can be determined in accordance with an opening ratio between the opening degree of an air passage on the indoor condenser 12 side and the opening degree of the cool air bypass passage 35 .

Hcin is an inlet-side enthalpy of the refrigerant on the inlet side of the indoor condenser 12. The inlet-side enthalpy Hcin can be determined from the discharge temperature Td and the discharge pressure Pd based on physical properties of the refrigerant.

Therefore, the supercooling degree estimating unit of the present embodiment can calculate the outlet-side enthalpy Hcout by using the formulas F4 to F6. Further, it is possible to estimate the degree of supercooling SC1 of the refrigerant flowing out of the indoor condenser 12 and flowing into the heater expansion valve 13 based on the outlet-side enthalpy Hcout and the discharge pressure Pd. Of course, the degree of dryness can also be estimated if the refrigerant that flows out of the indoor condenser 12 and flows into the heater expansion valve 13 is in a gas-liquid two-phase state.

The other configurations and operations of the refrigeration cycle device 10 and the vehicle air conditioner 1 are similar to those of the first embodiment. Therefore, the vehicle air conditioner 1 according to the present embodiment can also achieve cooling and dehumidification and heating of the inside of the vehicle cabin in a manner similar to the first embodiment. In addition, the refrigeration cycle device 10 of the present embodiment can obtain effects similar to those of the first embodiment.

That is, also in the refrigeration cycle device 10 of the present embodiment, it is possible to appropriately adjust the supercooling degree SC1 of the refrigerant on the outlet side of the indoor condenser 12, which is the heating unit.

The vehicle air conditioner 1 of the present embodiment has, as the auxiliary heating unit, the electric heater 37 that heats the ventilation air. With this configuration, the ventilation air can be heated by the electric heater 37 when the throttle opening degree of the heater expansion valve 13 cannot be reduced to adjust the supercooling degree SC1 to be equal to or lower than the target supercooling degree SCO. As a result, the blown air temperature TAV is increased to reach the target blowout temperature TAO, so that comfortable dehumidification and heating can be achieved.

The supercooling degree estimation unit of the present embodiment estimates the supercooling degree SC1 by using the refrigerant discharge flow rate Gr of the compressor 11, the discharge temperature Td, the discharge pressure Pd, an air blowing amount Airf of the indoor fan 32, the suction air temperature Tein and a heating amount Qh of the electric heater 37 . Therefore, the degree of supercooling SC1 can be accurately estimated only by adding the suction temperature sensor 41i as described in relation to the formulas F4 to F6.

The supercooling degree estimating unit of the present embodiment is also effective when applied to the refrigeration cycle device 10 that does not have the electric heater 37 . In that case, the heating amount Qh of the electric heater 37 may be set to 0.

(Fourth embodiment)

In the present embodiment, a description will be given using a refrigeration cycle device tion 10a given in 8th 12 is illustrated, in which a configuration of the heater unit is modified from the refrigeration cycle device 10 described in the first embodiment. The refrigeration cycle device 10a is applied to a vehicle air conditioner 1 similar to that of the first embodiment. The heater unit of the refrigeration cycle device 10a includes a medium/refrigerant heat exchanger 121, a heater core 53 arranged in a heat medium circuit 50, and the like.

The heat medium circuit 50 is a heat medium circulation circuit that circulates a heat medium. In the heat medium circuit 50, an ethylene glycol aqueous solution is used as the heat medium. In the heat medium circuit 50, a water passage of the medium/refrigerant heat exchanger 121, a heat medium pump 51, an electric heater 52, a heater core 53 and the like are arranged.

The medium/refrigerant heat exchanger 121 is a heat dissipation unit that exchanges heat between the high-pressure refrigerant discharged from the compressor 11 and the heat medium to dissipate heat of the high-pressure refrigerant to the ventilation air. In the present embodiment, a so-called counterflow heat exchanger is employed as the medium/refrigerant heat exchanger 121 . In the counterflow heat exchanger, the flow direction of the refrigerant flowing through the refrigerant passage and the flow direction of the heat medium flowing through the heat medium passage are opposite to each other.

The heat medium pump 51 is a heat medium pressure-feed unit that pressure-feeds the heat medium flowing out of the heater core 53 to the medium/refrigerant heat exchanger 121 . The heat medium pump 51 is an electric water pump that rotates an impeller (ie, an impeller) by an electric motor. A rotational speed (that is, a pressure delivery capacity) of the heat medium pump 51 is controlled by a control voltage that is output from the control device 40 .

The electric heater 52 heats the heat medium that flows out of the medium/refrigerant heat exchanger 121 . The electric heater 52 is an auxiliary heating unit that auxiliaryly heats the ventilation air via the heating medium when the blown air temperature TAV of the ventilation air cannot be raised to the target blowing temperature TAO solely by the heating capacity of the refrigeration cycle device 10 in the dehumidification-and-heating mode. As the electric heater 52, it is possible to use a PTC heater having a configuration similar to that of the electric heater 37 for ventilation air, or a different type heater.

The heater core 53 is a heat exchange unit for heating that heats the ventilation air by exchanging heat between the heating medium flowing out of the medium/refrigerant heat exchanger 121 and the ventilation air. The heater core 53 is arranged in the indoor air conditioning unit 30 in a manner similar to the indoor condenser 12 .

Further, a heat medium temperature sensor 41j as a sensor used for air conditioning control is connected to the input side of the control device 40 of the present embodiment. The heat-medium temperature sensor 41 j is inlet-side heat-medium temperature detection means that detects a heater-core inlet-side heat-medium temperature Twin of the heat medium flowing into the heater core 53 .

The supercooling degree estimating unit of the present embodiment estimates the supercooling degree SC1 by using the refrigerant discharge flow rate Gr of the compressor 11, the discharge temperature Td, the discharge pressure Pd, a heat medium flow rate LQf (a mass flow rate) of the heat medium that is discharged under pressure from the heat medium pump 51, the heater core inlet-side heat medium temperature Twin, the air-blowing amount Airf of the indoor fan 32, the suction temperature Ts, and the heating amount Qh2 of the electric heater 52 are used.

The degree of supercooling SC<b>1 of the present embodiment is a degree of supercooling of the refrigerant that flows out of the medium/refrigerant heat exchanger 121 forming the heater unit and flows into the heater expansion valve 13 .

The refrigerant discharge flow rate Gr of the compressor 11 can be calculated in a manner similar to the first embodiment. The discharge temperature Td and the discharge pressure Pd are used to determine an inlet-side enthalpy Hwcin of the refrigerant on the inlet side of the medium-refrigerant heat exchanger 121 in a manner similar to the third embodiment. The heat-medium flow rate LQf of the heat-medium pump 51 can be determined from a specification of the heat-medium pump 51 and a control voltage that the control device 40 outputs to the heat-medium pump 51 .

The air blowing amount Airf of the indoor fan 32 can be determined in a manner similar to the third embodiment. The suction temperature Ts is used to determine a cooling air temperature Tae of cooling air that is cooled in the indoor evaporator 17 and flows into the heater core 53 . Specifically, the cool air temperature Tae may be set to a value obtained by subtracting a superheat degree (3°C in the present embodiment) of the refrigerant on the outlet side of the indoor evaporator 17 from the suction temperature Ts.

The heating amount Qh2 of the electric heater 52 can be determined based on a specification of the electric heater 52 and the amount of current that the control device 40 outputs to the electric heater 52 .

$$\text{Qwr}=\text{f}\left(\text{LQf},\text{Twin},\text{Airfh},\text{Tae}\right)$$

$$\text{Qwex}=\text{Gr}\times \left(\text{Hwcin}-\text{Hwcout}\right)$$

Hier ist Qwr eine Wärmemenge, die von dem Wärmemedium in dem Heizungskern 53 an die Lüftungsluft abgeleitet wird. Qwex ist ein Betrag einer Wärmeableitung von dem Kältemittel, das in dem Medium/Kältemittel-Wärmetauscher 121 kondensiert wird, an das Wärmemedium.The supercooling degree estimating unit of the present embodiment calculates an outlet-side enthalpy Hwcout of the refrigerant on the outlet side of the medium-refrigerant heat exchanger 121 based on the following formulas F7 to F9. $$\text{Qwr}=\text{Qwex}+\text{uh}2$$

$$\text{Qwr}=\text{f}\left(\text{LQf},\text{twins},\text{Airfh},\text{tae}\right)$$

$$\text{Qwex}=\text{size}\times \left(\text{Hwcin}-\text{Hwcout}\right)$$

Here, Qwr is an amount of heat dissipated from the heat medium in the heater core 53 to the ventilation air. Qwex is an amount of heat dissipation from the refrigerant condensed in the medium/refrigerant heat exchanger 121 to the heat medium.

Airfh is a heater core side air volume of the ventilation air passing through the heater core 53 . In the dehumidification-and-heating mode of the present embodiment, since the air mix door 34 completely closes the cold air bypass passage 35 , the heater core side air volume Airfh is equal to the air blowing amount Airf. When the cool air bypass passage 35 is opened by the air mix door 34 , the heater core side air volume Airfh can be determined in accordance with an opening ratio between the opening degree of an air passage on the heater core 53 side and the opening degree of the cool air bypass passage 35 .

The formula F8 indicates that Qwr is determined based on the heat medium flow rate LQf, the heater core inlet side heat medium temperature Twin, the heater core side air volume Airfh, and the cooling air temperature Tae. That is, the amount of heat exchange between the refrigerant and the heating medium in the heater core 53 can be determined based on the temperature and the air volume of the refrigerant flowing into the heater core 53, the temperature and the air volume of the heating medium flowing into the heater core 53 , and a heat exchange performance of the heater core 53 can be determined.

Therefore, in the present embodiment, the amount of heat dissipation from the refrigerant condensed in the medium/refrigerant heat exchanger 121 to the heat medium based on the heat medium flow rate LQf with respect to a previously stored control map, the heater core inlet side heat medium temperature Twin, the heater core side Air volume Airfh and the cooling air temperature Tae are determined. The heat exchange performance of the heater core 53 can be obtained from a specification of the heater core 53, test data, and the like.

Therefore, in the present embodiment, the outlet-side enthalpy Hwcout can be calculated using Formulas F7 to F9. Further, it is possible to estimate the supercooling degree SC1 of the refrigerant that flows out of the heater core 53 and flows into the heater expansion valve 13 based on the outlet-side enthalpy Hwcout and the discharge pressure Pd. Of course, the degree of dryness can also be estimated if the refrigerant that flows out of the heater core 53 and flows into the heater expansion valve 13 is in a gas-liquid two-phase state.

Other configurations and an operation of the refrigeration cycle device 10a are similar to those of the refrigeration cycle device 10 of the first embodiment. Therefore, the vehicle air conditioner 1 according to the present embodiment can also achieve cooling and dehumidification and heating of the inside of the vehicle cabin in a manner similar to the first embodiment. In addition, the refrigeration cycle device 10a of the present embodiment can obtain effects similar to those of the first embodiment.

That is, also in the refrigeration cycle device 10 of the present embodiment, it is possible to appropriately adjust the supercooling degree SC1 of the refrigerant on the outlet side of the medium-refrigerant heat exchanger 121 constituting the heating unit. As a result, a reduction in the COP of the refrigeration cycle device 10 can be suppressed.

The vehicle air conditioner 1 of the present embodiment includes, as the auxiliary heating unit, the electric heater 52 that heats the heat medium. Therefore, when the throttle opening degree of the heater expansion valve 13 cannot be reduced to adjust the supercooling degree SC<b>1 to be equal to or lower than the target supercooling degree SCO, the heating medium can be heated by the electric heater 52 . As a result, the blown air temperature TAV is increased to reach the target blowout temperature TAO, so that comfortable dehumidification and heating can be achieved.

The supercooling degree estimation unit of the present embodiment estimates the supercooling degree SC1 by using the refrigerant discharge flow rate Gr of the compressor 11, the discharge temperature Td, the discharge pressure Pd, a heat medium flow rate LQf of the heat medium pump 51, the heater core inlet-side heat medium temperature Twin, the air blowing amount Airf of the indoor fan 32, the suction temperature Ts and the heating amount Qh2 of the electric heater 52 can be used. Therefore, the degree of supercooling SC1 can be accurately estimated only by adding the heat medium temperature sensor 41j as described in relation to the formulas F7 to F9.

The supercooling degree estimating unit of the present embodiment is also effective when applied to the refrigeration cycle device 10 a that does not have the electric heater 52 . In that case, the heating amount Qh2 of the electric heater 52 may be set to zero.

(Fifth embodiment)

In the present embodiment, a description will be given by way of an example in which an estimation form of the degree of supercooling SC1 in the degree of supercooling estimating unit is modified from that in the fourth embodiment.

As described in the fourth embodiment, the refrigeration cycle device 10 a employs a counterflow heat exchanger as the medium/refrigerant heat exchanger 121 . In the counterflow heat exchanger, the flow direction of the refrigerant flowing through the refrigerant passage and the flow direction of the heat medium flowing through the heat medium passage are opposite to each other. Therefore, the temperatures of the refrigerant and the heating medium change, as in 9 is shown. In 9 the thick solid line represents a temperature change of the refrigerant, and the thick broken line represents a temperature change of the heating medium.

Accordingly, in the medium/refrigerant heat exchanger 121, a heater core outlet-side thermal medium temperature Twout of the thermal medium that flows out of the heater core 53 and flows into the thermal medium passage has a value that is comparatively close to a water/refrigerant outlet-side refrigerant temperature Tdout of the refrigerant that is discharged flows out of the refrigerant passage. In addition, the heater core outlet-side heat medium temperature Twout has a lower value than the water/refrigerant outlet-side refrigerant temperature Tdout.

Therefore, assuming that the heater core outlet-side heat medium temperature Twout is the water/refrigerant outlet-side refrigerant temperature Tdout, it is possible to estimate the supercooling degree SC1 having a value larger than the actual value, that is, it is possible estimate a worst case subcooling degree SCO1 on the crossing side.

Therefore, the supercooling degree estimating unit of the present embodiment estimates the supercooling degree SC1 by using the discharge pressure Pd, the heat medium flow rate LQf pumped by the heat medium pump 51 under pressure, the heater core inlet-side heat medium temperature Twin, the air blowing amount Airf of the indoor fan 32, and the suction temperature Ts be used. The air-blowing amount Airf is used to determine the heater-core-side air volume Airfh in a manner similar to the fourth embodiment. The suction temperature Ts is used to determine the cooling air temperature Tae in a manner similar to the fourth embodiment.

Then, in a manner similar to Formula F8 of the fourth embodiment, the heater core outlet side heat medium temperature Twout is determined with reference to a pre-stored control map based on the heat medium flow rate LQf, the heater core inlet side heat medium temperature Twin, the heater core side air volume Airfh, and the cooling air temperature Tae. Further, the supercooling degree SC1 of the refrigerant that flows out of the medium-refrigerant heat exchanger 121 and flows into the heater expansion valve 13 is estimated based on the heater core outlet-side thermal medium temperature Twout and the discharge pressure Pd.

The other configurations and the operation of the refrigeration cycle device 10a are similar to those of the fourth embodiment. Therefore, the vehicle air conditioner 1 according to the present embodiment can also achieve cooling and dehumidification and heating of the inside of the vehicle cabin in a manner similar to the fourth embodiment. In addition, the refrigeration cycle device 10a of the present embodiment can obtain effects similar to those of the fourth embodiment.

That is, also in the refrigeration cycle device 10 of the present embodiment, it is possible to appropriately adjust the supercooling degree SC1 of the refrigerant on the outlet side of the medium-refrigerant heat exchanger 121 constituting the heating unit.

For the supercooling degree estimating unit of the present embodiment, an example in which the heater core outlet-side heating medium temperature Twout is used as the water/refrigerant outlet-side refrigerant temperature Tdout has been described; however, the present embodiment is not limited to this. For example, it is possible to use a value obtained by adding a predetermined value to the heater core outlet-side heat medium temperature Twout as the water/refrigerant outlet-side refrigerant temperature Tdout.

The present disclosure is not limited to the above-described embodiments, and can be variously modified as follows without departing from the gist of the present disclosure.

The cycle configuration of the refrigeration cycle device according to the present disclosure is not limited to the configurations of the refrigeration cycle devices 10 and 10a disclosed in the above-described embodiments.

For example, the refrigeration cycle device may be configured as follows. The refrigerant cycle of the refrigeration cycle device can be switched, and in a predetermined operation mode, a refrigerant cycle similar to those in the above-described embodiments is formed. When the refrigerant cycle is switched to the refrigerant cycle similar to those in the above-described embodiments, the same control as that of the above-described embodiments is performed, whereby the same effects as those of the above-described embodiments can be obtained.

In the above-described embodiments, examples have been described in which the header 15 is connected to the refrigerant outlet of the outdoor heat exchanger 14; however, the present invention is not limited thereto. For example, in the refrigeration cycle device having the supercooling degree estimation units described in the third to fifth embodiments, the accumulator 15 can be eliminated and an accumulator can be attached to the refrigerant flow passage from the refrigerant outlet of the indoor evaporator 17 to the suction port of the compressor 11 be provided.

The accumulator is a low-pressure liquid reservoir that separates the refrigerant flowing out of the indoor evaporator 17 into a gas and a liquid, causing the separated gas-phase refrigerants to flow out to the suction port side of the compressor 11 while the separated liquid-phase refrigerant as a excess refrigerant of the circuit is stored. In the refrigeration cycle device including the accumulator, the outdoor heat exchanger 14 can be made to function as an evaporator that evaporates the refrigerant at the time of the blow-out temperature control in the dehumidification-and-heating mode.

The constituent devices of the refrigeration cycle devices 10 and 10a are not limited to the constituent devices disclosed in the above-described embodiments.

For example, as the compressor 11, it is possible to employ an engine-driven compressor that is driven by a rotational driving force transmitted from an internal combustion engine (ie, an engine). In the engine-driven compressor, the refrigerant discharge flow rate Gr can be calculated considering the engine speed, the discharge capacity, the operation rate, or the like.

Further, in each of the third to fifth embodiments described above, an example has been described in which a minimum number of detectors are added to the detectors essential to the blowout temperature control and the compressor protection control, but the addition of the detector is not limited to this. For example, a flow rate sensor can be added as flow rate detection means to directly detect the refrigerant discharge flow rate Gr (a mass flow rate) of the compressor 11 .

In each of the above-described embodiments, an example in which R1234yf is used as the refrigerant for the refrigeration cycle devices 10 and 10a has been described, but the refrigerant is not limited to this. For example, R134a, R600a, R410A, R404A, R32, R407C and the like can be used. Alternatively, a mixed refrigerant obtained by mixing a plurality of these refrigerants or another refrigerant may be used.

In each of the above-described embodiments, an example in which an ethylene glycol aqueous solution is used as the heating medium has been described, but the heating medium is not limited to this. For example, it is possible to use the following media: a solution containing dimethylpolysiloxane, a nanofluid, or the like; an antifreeze liquid; an aqueous liquid medium containing alcohol or the like; and a liquid medium containing oil or the like.

The control modes of the refrigeration cycle devices 10 and 10a are not limited to the control forms disclosed in the above-described embodiments.

For example, the target supercooling degree determining units of the first to third embodiments can determine such a target supercooling degree SCO that can suppress the temperature unevenness generated in the ventilation air. Specifically, the target supercooling degree SCO can be determined in such a manner that the temperature difference obtained by subtracting the minimum temperature of the ventilation air after passing through the indoor condenser 12 or the heater core 53 from the maximum temperature , is equal to or lower than a predetermined reference temperature difference.

The means disclosed in each of the above embodiments can be appropriately combined within an operable range.

For example, as the heating unit of the refrigeration cycle device 10 described in the first and second embodiments, it is possible to employ various dividing devices arranged in the medium/refrigerant heat exchanger 121 and the heating medium circuit 50 described in the fourth embodiment are. In other words, it is possible to apply to the refrigeration cycle device 10a described in the fourth embodiment the supercooling degree estimation unit described in the first embodiment or the lower interface calculation unit described in the second embodiment.

Although the present disclosure has been described in accordance with examples, it should be understood that the present disclosure is not limited to the examples or the structures. The present disclosure also includes various modified examples and modifications within an equivalent range. In addition, the following are also within the scope and spirit of the present invention: various combinations and forms; and other combinations and forms in which only one element, multiple elements, or fewer elements are included in the various combinations and forms.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• JP 2020139066 [0001]
• JP 5585549 [0007]

Claims (9)

Refrigeration circuit device with: a compressor (11) configured to compress and discharge a refrigerant; a heater unit (12, 121, 50) configured to heat ventilation air to be blown into a space to be air-conditioned by using the refrigerant discharged from the compressor (11) as a heat source; a first expansion unit (13) configured to expand the refrigerant flowing out of the heating unit; an outdoor heat exchange unit (14) configured to exchange heat between the refrigerant flowing out of the first expansion unit and outdoor air; a second expansion unit (16) configured to expand the refrigerant flowing out of the outdoor heat exchange unit; an indoor evaporation unit (17) configured to evaporate the refrigerant expanded in the second expansion unit to cool the ventilation air before it is heated in the heating unit; a target supercooling degree determining unit (S1) configured to determine a target supercooling degree (SCO) of the refrigerant flowing into the first expansion unit; a supercooling degree estimating unit (S2) configured to estimate a supercooling degree (SC1) of the refrigerant flowing into the first expansion unit; and a first relaxation control unit (40b) configured to control an operation of the first relaxation unit, wherein the first relaxation control unit controls the operation of the first relaxation unit so that the supercooling degree (SC1) estimated by the supercooling degree estimating unit is equal to or lower than the target supercooling degree (SCO). refrigeration cycle device claim 1 , wherein the degree of supercooling estimating unit estimates the degree of supercooling (SC1) by using a refrigerant discharge flow rate (Gr) of the compressor, an opening degree (A) of the first expansion unit, a discharge pressure (Pd) of the refrigerant discharged from the compressor, and an outside air temperature ( Tam) are used. refrigeration cycle device claim 1 , further comprising a blower unit (32) configured to blow the ventilation air, the heating unit having an indoor condenser (12) that exchanges heat between the refrigerant discharged from the compressor and the ventilation air, and the Subcool degree estimation unit estimates the degree of supercooling (SC1) by using a refrigerant discharge flow rate (Gr) of the compressor, a discharge temperature (Td) of the refrigerant discharged from the compressor, a discharge pressure (Pd) of the refrigerant discharged from the compressor Air blowing amount (Airf) of the blower unit and a suction air temperature (Tein) of the ventilation air flowing into the indoor evaporative unit are used. refrigeration cycle device claim 1 , further comprising a blower unit (32) configured to blow the ventilation air, the heater unit comprising: a medium/refrigerant heat exchanger (121) that heats between the refrigerant discharged from the compressor and a heating medium exchanges a heater core (53) that exchanges heat between the heating medium heated in the medium/refrigerant heat exchanger and the ventilation air; and a heat medium pressure feeding unit (51) that feeds the heat medium heated in the medium/refrigerant heat exchanger (121) to the heater core (53) under a pressure, and the supercooling degree estimating unit estimates the supercooling degree (SC1), by a refrigerant discharge flow rate (Gr) of the compressor, a discharge temperature (Td) of the refrigerant discharged from the compressor, a discharge pressure (Pd) of the refrigerant discharged from the compressor, a heat-medium flow rate (LQf) of the heat-medium pressure feed unit, a heater core inlet side heat medium temperature (Twin) of the heat medium flowing into the heater core, an air blowing amount (Airf) of the blower unit, and a suction temperature (Ts) of the refrigerant to be sucked into the compressor. refrigeration cycle device claim 1 further comprising a blower unit (32) that blows the ventilation air, the heater unit comprising: a medium/refrigerant heat exchanger (121) that exchanges heat between the refrigerant discharged from the compressor and a heat medium; a heater core (53) that exchanges heat between the heating medium heated in the medium/refrigerant heat exchanger and the ventilation air; and a heat-medium pressure-supply unit (51) which pressure-supplies the heat medium heated in the medium/refrigerant heat exchanger (121) to the heater core, the medium/refrigerant heat exchanger being a counterflow type heat exchanger in which a flow direction of the Refrigerant through a refrigerant passage flows, and a flow direction of the heat medium flowing through a heat medium passage are opposite to each other, and the degree of subcooling estimating unit estimates the degree of supercooling (SC1) by comparing a discharge pressure (Pd) of the refrigerant discharged from the compressor with a heat medium flow rate ( LQf) of the heat medium pressure feed unit, a heater core inlet side heat medium temperature (Twin) of the heat medium flowing into the heater core, an air blowing amount (Airf) of the blower unit, and a suction temperature (Ts) of the refrigerant to be sucked into the compressor. Refrigeration circuit device with: a compressor (11) configured to compress and discharge the refrigerant; a heater unit (12, 121, 50) configured to heat ventilation air to be blown into a space to be air-conditioned by using the refrigerant discharged from the compressor as a heat source; a first expansion unit (13) configured to expand the refrigerant flowing out of the heating unit; an outdoor heat exchange unit (14) configured to exchange heat between the refrigerant flowing out of the first expansion unit and outdoor air; a second expansion unit (16) configured to expand the refrigerant flowing out of the outdoor heat exchange unit; an indoor evaporation unit (17) configured to evaporate the refrigerant expanded in the second expansion unit to cool the ventilation air before it is heated in the heating unit; a target supercooling degree determining unit (S11) configured to determine a target supercooling degree (SCO) of the refrigerant flowing into the first expansion unit; a lower limit area calculation unit (S12) configured to calculate a lower limit of a throttle passage area (Amin) of the first expansion unit so that a supercooling degree (SC1) of the refrigerant flowing into the first expansion unit is equal to the target supercooling degree (SCO) becomes; and a first relaxation control unit (40b) configured to control an operation of the first relaxation unit, wherein the first relaxation control unit controls the operation of the first relaxation unit so that a throttle passage area (A) of the first relaxation unit is equal to or larger than the lower limit of a throttle passage area (Amin). refrigeration cycle device claim 6 , wherein the lower limit area calculation unit calculates the lower limit of a throttle passage area (Amin) by using the target supercooling degree (SCO), a refrigerant discharge flow rate (Gr) of the compressor, an inlet-side pressure (P1) of the refrigerant flowing into the first expansion unit , and a downstream pressure (P2) of the refrigerant flowing out of the first expansion unit can be used. refrigeration cycle device claim 7 wherein the lower interface calculation unit uses, as the inlet-side pressure (P1) of the refrigerant flowing into the first expansion unit, a discharge pressure (Pd) of the refrigerant discharged from the compressor. refrigeration cycle device claim 7 or 8th , wherein the lower interface calculation unit uses, as the outlet-side pressure (P2) of the refrigerant flowing out of the first expansion unit, a value determined using an outside air temperature (Tam).

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