Patent Application
20170217286
1. Technical Field
The present disclosure relates to an air-conditioning control device, a vehicle air-conditioning device, and a method for determining a fault, in an electromagnetic valve of an air-conditioning control device.
2. Description of the Related Art
As a vehicle air-conditioning device, there has conventionally been a system including a refrigerant passage for cooling and a refrigerant passage for heating, and provided with an ON-OFF valve (for example, three-way valve) for switching the two refrigerant, passages (for example, U.S. Pat. No. 6,640,889). A compressor, a condenser, an expansion valve, and an evaporator are provided on the refrigerant passages, and the compressor is shared by the refrigerant, passage for cooling and the refrigerant passage for heating. This vehicle air-conditioning device controls the ON-OFF valve to cause a refrigerant to flow through one of the two refrigerant, passages, thereby switching an operating mode such as a cooling mode or a heating mode.
An object, of the present disclosure is to provide an air-conditioning control device that can quickly detect an abnormal flow of a refrigerant caused by a fault in an ON-OFF valve with reduced cost, and a vehicle air-conditioning device provided with the air-conditioning control device.
An air-conditioning control device according to one aspect of the present disclosure controls an air-conditioning device including a first heat exchanger and a first opening and closing portion. The first heat exchanger exchanges heat between a high-temperature and high-pressure refrigerant discharged from a compressor and air or a first heating medium which is a coolant. The first opening and closing portion opens and closes a refrigerant passage between the compressor and the first heat exchanger according to a command. The air-conditioning control device further includes a pressure acquisition unit, a temperature acquisition unit, and a determination unit. The pressure acquisition unit, acquires a detection value from a first pressure sensor that detects a pressure of a refrigerant flowing from the first heat exchanger. The temperature acquisition unit acquires a detection value from a first temperature sensor that detects a temperature of the first heating medium flowing through the first heat, exchanger. When a command is issued to cause a refrigerant to flow through the first opening and closing portion in a state where the refrigerant is not flowing through the first, opening and closing portion, the determination unit determines whether or not the first opening and closing portion is normally opened to cause the refrigerant to flow through the first heat exchanger, by using the pressure of the refrigerant detected by the first pressure sensor and the temperature of the first heating medium detected by the first temperature sensor.
A vehicle air-conditioning device according to one aspect of the present disclosure is an air-conditioning control device that controls an air-conditioning device including: a first heat exchanger that exchanges heat between a high-temperature and high-pressure refrigerant discharged from a compressor and air or a first heating medium which is a coolant; and a first opening and closing portion, that opens and closes a refrigerant passage between the compressor and the first heat exchanger according to a command. The vehicle air-conditioning device includes a second heat exchanger that, exchanges heat between a high-temperature and high-pressure refrigerant discharged from the compressor and air or a second heating medium that, is a coolant; a second opening and closing portion that opens and closes a refrigerant passage between the compressor and the second heat exchanger according to a command; a first pressure sensor that detects a pressure of a refrigerant flowing from the first heat exchanger: a second pressure sensor that detects a pressure of a refrigerant flowing from the second heat exchanger; a pressure acquisition unit that acquires detection values from the first pressure sensor and the second pressure sensor; a first temperature sensor that detects a temperature of the first heating medium flowing in the first heat exchanger; a second temperature sensor that detects a temperature of the second heating medium flowing in the second heat exchanger; a temperature acquisition unit that acquires detection values from the first, temperature sensor and the second temperature sensor; and an air-conditioning control unit that controls the vehicle air-conditioning device. The air-conditioning control unit includes: a determination unit that, when a command is issued to cause a refrigerant to flow through the first opening and closing portion in a state where the refrigerant is not flowing through the first opening and closing portion, determines whether or not the first opening and closing portion is normally opened to cause the refrigerant to flow through the first heat, exchanger, by rising the pressure of the refrigerant detected by the first pressure sensor and the temperature of the first heating medium detected by the first temperature sensor. The determination unit further determines that, when a command is issued to cause a refrigerant to flow through the second opening and closing portion in a state where the refrigerant, is not flowing through the second opening and closing portion, determines whether or not the second opening and closing portion is normally opened to cause the refrigerant to flow through the second heat exchanger, by using the pressure of the refrigerant detected by the second pressure sensor and the temperature of the second heating medium detected by the second temperature sensor.
The air-conditioning control unit detects, based on a determination result of the determination unit, an occurrence of an abnormal situation in which the compressor is activated and the first opening and closing portion and the second opening and closing portion are both closed.
According to the present disclosure, an abnormal flow of a refrigerant caused by a fault in an ON-OFF valve can quickly be detected with reduced cost.
Prior to the description of an exemplary embodiment of the present disclosure, a problem of a conventional device will briefly be described. Upon switching an operating mode, if an ON-OFF valve is not opened due to a fault and two refrigerant, passages are thereby simultaneously blocked, a refrigerant discharged from a compressor would have nowhere to go, so the discharge pressure in the compressor would be abnormally increased. To detect such an abnormal condition, one can consider providing a pressure sensor for detecting the pressure of the refrigerant between a discharge port of the compressor and the ON-OFF valve. In this configuration, however, the pressure sensor is exposed to the high-temperature and high-pressure refrigerant discharged from the compressor, so the pressure sensor needs to be configured to have high heat resistance, which leads to an increase in cost. Also, to detect the abnormal condition mentioned above, one can consider the ON-OFF valve detecting its own open or closed state and outputting the detection result to a controller. Such ON-OFF valve, however, is expensive and increases the component cost.
An exemplary embodiment of the present disclosure will be described below in detail with reference to the drawings.
The vehicle air-conditioning device according to the exemplary embodiment, of the present disclosure is a device mounted on a vehicle for performing air-conditioning in a vehicle interior.
The vehicle air-conditioning device according to the exemplary embodiment includes compressor 38, engine cooling portion 40, heater core 44, cooling evaporator 48, expansion valve 37, outdoor condenser (corresponding to a first heat exchanger) 39, check valve 15, water refrigerant evaporator 11, water-refrigerant condenser (corresponding to a second heat exchanger) 12, expansion valve 14, and a coolant pipe and a refrigerant pipe which connect between these components. The vehicle air-conditioning device according to the exemplary embodiment, further includes electromagnetic valves 10 and 13, first temperature sensor 18, second temperature sensor 19, first pressure sensor 16, second pressure sensor 17, and air-conditioning controller (corresponding to an air-conditioning control device) 52. Heater core 44 and cooling evaporator 48 are disposed in an intake passage of HVAC (Heating, Ventilation, and air conditioning) 70. HVAC 70 is provided with fan F1 that circulates intake air.
Compressor 38 is driven by engine power or electric power, compresses the suctioned low-temperature refrigerant to a high-temperature and high-pressure state, and discharges the resultant refrigerant. A low-pressure refrigerant is delivered through a junction pipe from water-refrigerant evaporator 11 or from cooling evaporator 48. The compressed refrigerant is delivered to water-refrigerant condenser 12 or outdoor condenser 89.
Engine cooling portion 40 includes a water jacket that circulates a coolant around the engine and a pump that circulates the coolant through the water jacket and radiates heat from the engine to the coolant flowing through the water jacket. The pump is rotated by engine power, for example. Engine cooling portion 40 may be provided with a radiator that radiates heat to outside air when the amount of waste heat from the engine is increased.
The coolant may be an antifreeze such as LLC (Long Life Coolant) for transporting heat.
Heater core 44 is a device for performing heat exchange between the coolant and air, and is disposed in the intake passage in HVAC 70 that supplies air to the vehicle interior. Heater core 44 is supplied with the heated coolant and radiates heat into the intake air to be sent to the vehicle interior (air to be sent to the vehicle interior) during a heating operation. Heater core 44 can adjust the amount of passing air according to the opening degree of door 44a. Door 44a is openable under an electric control. Door 44a may be referred to as an air-mix door.
Although not particularly limited, the passage for the coolant is configured to cause the coolant to sequentially circulate and flow through, engine cooling portion 40, water-refrigerant condenser 12, heater core 44, and water-refrigerant evaporator 11, and then, back to engine cooling portion 40. Note that various modifications are possible for the passage for the coolant, For example, a first passage for the coolant and a second passage for the coolant may be formed, the first passage causing the coolant to circulate and flow through engine cooling portion 40, water-refrigerant condenser 12, and heater core 44, the second passage causing the coolant, to circulate and flow through water-refrigerant evaporator 11 and a radiator. In addition, the passage for the coolant may be configured such that the coolant delivered from engine cooling portion 40 is separated into two passages to flow through water-refrigerant evaporator 11 and water-refrigerant condenser 12 in a parallel manner, and then, supplied to heater core 44.
Cooling evaporator 48 is a device for performing beat exchange between a low-temperature and low-pressure refrigerant and air, and disposed in the intake passage in HVAC 70. Cooling evaporator 48 is supplied with the low-temperature and low-pressure refrigerant in a cooling mode, a dehumidification mode, and a temperature control mode, and cools the intake air to be supplied to the vehicle interior.
Expansion valve 37 expands a high-pressure refrigerant to a low-temperature and low-pressure state and discharges the refrigerant, to cooling evaporator 48. Expansion valve 37 is disposed close to cooling evaporator 48. Expansion valve 37 may be a thermal expansion valve (TXV) having a function of automatically adjusting the amount of the discharged refrigerant according to the temperature of the refrigerant sent from cooling evaporator 48.
Outdoor condenser 39 has a passage for the flow of the refrigerant and a passage for the flow of the air, is placed near the front of the vehicle in an engine room, for example, and exchanges heat between the refrigerant and the outside air. In the cooling mode or the dehumidification mode, outdoor condenser 39 is supplied with a high-temperature and high-pressure refrigerant, and discharges heat from the refrigerant to the outside air. The outside air is blown over outdoor condenser 39 by a fan, for example. Reservoir tank 39a may be provided to outdoor condenser 39 at the outlet side of the refrigerant.
Water refrigerant-evaporator 11 (evaporator) includes a passage for the flow of the low-temperature and low-pressure refrigerant and a passage for the flow of the coolant, and exchanges heat between the refrigerant and the coolant. In a predetermined operating mode, water-refrigerant evaporator 11 is supplied with the low-temperature and low-pressure refrigerant from expansion valve 14, and transfers heat from the coolant to the low-temperature and low-pressure refrigerant. Thus, water-refrigerant evaporator 11 vaporizes the low-temperature and low-pressure refrigerant. A refrigerant inlet of water refrigerant evaporator 11 is communicated with expansion valve 14 through a pipe, and a refrigerant outlet is communicated with a pipe which is joined to an intake port of compressor 38.
Water refrigerant condenser 12 (condenser) includes a passage for the flow of the high-temperature and high-pressure refrigerant and a passage for the flow of the coolant, and exchanges heat between the refrigerant and the coolant. In a predetermined operating mode, water refrigerant condenser 12 is supplied with the high-temperature and high-pressure refrigerant from compressor 38 and heat is radiated from the high-temperature and high-pressure refrigerant to the coolant. Thus, water-refrigerant condenser 12 condenses the high-temperature and high-pressure refrigerant. A refrigerant inlet of water-refrigerant condenser 12 is communicated with a discharge port of compressor 38 through a pipe, and a refrigerant outlet is communicated with expansion valve 14 through a pipe.
Electromagnetic valves 10 and 13 are valves that switch between opening and closing of the refrigerant pipe under the control from later-described air-conditioning controller 52. Electromagnetic valve 10 (corresponding to a first opening and closing portion) is provided on the refrigerant pipe between compressor 38 and outdoor condenser 39. Electromagnetic valve 13 (corresponding to a second opening and closing portion) is provided on the refrigerant pipe between compressor 38 and water-refrigerant condenser 12. When electromagnetic valve 10 is opened and electromagnetic valve 13 is closed, a refrigerant passage for cooling is formed through which the refrigerant discharged from compressor 38 flows through outdoor condenser 39, expansion valve 37, cooling evaporator 48, and check valve 15, and then, returns to compressor 38. In addition, when electromagnetic valve 10 is closed and electromagnetic valve 13 is opened, a refrigerant passage for heating is formed through which the refrigerant discharged from compressor 38 flows through water-refrigerant condenser 12, expansion valve 14, and water refrigerant evaporator 11, and then, returns to compressor 38.
Expansion valve 14 expands a high-pressure refrigerant sent from water-refrigerant condenser 12 and delivers this refrigerant to water-refrigerant evaporator 11. Expansion valve 14 may be a thermal expansion valve (TXV) having a function of automatically adjusting the flow amount of the refrigerant based on the temperature of the refrigerant at the refrigerant outlet port of water-refrigerant evaporator 11.
Check valve 15 is a valve provided to the refrigerant pipe between compressor 38 and cooling evaporator 48 to prevent, a backflow of the refrigerant in an operating mode in which the refrigerant does not flow into outdoor condenser 39 and cooling evaporator 48.
Second temperature sensor 19 detects the temperature (also referred to as a water temperature) of the coolant and outputs a water temperature signal indicating the water temperature to air-conditioning controller 52. Second temperature sensor 19 detects the temperature of the coolant at the inlet of water-refrigerant condenser 12, for example. Second temperature sensor 19 may detect the temperature at other portions such as at the outlet of engine cooling portion 40, so long as the temperature of the coolant flowing through water refrigerant condenser 12 can be estimated from the detection result.
First temperature sensor 18 detects the temperature (also referred to as an outside temperature) of the outside air and outputs an outside temperature signal indicating the outside temperature to air-conditioning controller 52. First temperature sensor 18 detects the temperature of the outside air, at the inlet, introduced into outdoor condenser 39, for example. First temperature sensor 18 may detect the temperature at other portions such as on a location distant from outdoor condenser 39, so long as the temperature of the outside air flowing in outdoor condenser 39 can be estimated from the detection result.
First pressure sensor 16 detects the pressure of the refrigerant sent from outdoor condenser 39, and outputs a first refrigerant pressure signal indicating the detected pressure to air-conditioning controller 52. First pressure sensor 16 may detect the pressure of the refrigerant in the middle of the refrigerant passage of outdoor condenser 39. Preferably the first pressure sensor is disposed on the refrigerant passage at the downstream side with respect to the refrigerant inlet of outdoor condenser 39. According to this arrangement, heat resistance property allowed for first pressure sensor 16 can be lowered.
Second pressure sensor 17 detects the pressure of the refrigerant sent from water-refrigerant condenser 12, and outputs a second refrigerant pressure signal indicating this detected pressure to air-conditioning controller 52. Second pressure sensor 17 may detect the pressure of the refrigerant in the middle of the refrigerant passage of water-refrigerant condenser 12. Preferably, second pressure sensor is disposed on the refrigerant passage at the downstream side with respect to the refrigerant inlet of water refrigerant condenser 12. According to this arrangement, heat resistance property allowed for second pressure sensor 17 can be lowered.
Air-conditioning controller 52 can be composed of a microcomputer or a sequencer. Air-conditioning controller 52 performs open and close control of electromagnetic valves 10 and 13 by outputting an electromagnetic valve control signal as an opening and closing command. According to this control, the operating mode of the vehicle air-conditioning device is switched.
In addition, air-conditioning controller 52 determines a fault in electromagnetic valves 10 and 13. For this determination, air-conditioning controller 52 acquires the first refrigerant pressure signal indicating the pressure of the refrigerant from outdoor condenser 39 from first pressure sensor 16, and acquires the second refrigerant pressure signal indicating the pressure of the refrigerant from water-refrigerant condenser 12 from second pressure sensor 17. Air-conditioning controller 52 also acquires the outside temperature signal from first temperature sensor 18 and the water temperature signal from second temperature sensor 19.
Air-conditioning controller 52 estimates the temperature of the refrigerant based on the acquired first refrigerant pressure signal. Since a constant relationship is established between pressure and temperature of the refrigerant, the refrigerant temperature can easily be obtained from the refrigerant pressure when the flow of the refrigerant is stopped. Air-conditioning controller 52 determines whether or not following formula (1) is satisfied using the estimated refrigerant temperature and the outside temperature.
(Estimated temperature of refrigerant from outdoor condenser 39)−(outside temperature)<K1 (1)
In formula (1), K1 is a predetermined threshold, and set to a few ° C., for example.
When the flow of the refrigerant in outdoor condenser 39 is stopped, the stagnant refrigerant in outdoor condenser 39 exchanges heat with outside air, so that the difference between the refrigerant temperature and the outside temperature is decreased. If there is a variation in the outside temperature, the pressure of the refrigerant also varies with this variation. On the other hand, when the high-temperature and high-pressure refrigerant is supplied to outdoor condenser 39 from compressor 38, the pressure of the refrigerant in outdoor condenser 39 rises and the estimated refrigerant temperature also rises, regardless of the outside temperature. Therefore, when the determination formula (1) is satisfied, it can be determined that the refrigerant is not flowing in outdoor condenser 39, so that the electromagnetic valve 10 can be determined to be closed.
In addition, air-conditioning controller 52 estimates the refrigerant temperature based on the acquired second refrigerant pressure signal, and determines whether or not following formula (2) is satisfied using the estimated refrigerant temperature and the temperature of the coolant.
(Estimated temperature of refrigerant from water-refrigerant condenser 12−temperature of coolant)<K2 (2)
In formula (2), K2 is a predetermined threshold, and set to a few ° C., for example.
When the flow of the refrigerant in water-refrigerant condenser 12 is stopped, the stagnant refrigerant in water-refrigerant condenser 12 exchanges heat with the coolant, so that the difference between the refrigerant temperature and the coolant temperature is decreased. If there is a variation in the coolant temperature, the pressure of the refrigerant also varies with this variation. On the other hand, when the high-temperature and high-pressure refrigerant is supplied to water-refrigerant condenser 12 from compressor 38, the pressure of the refrigerant in water-refrigerant condenser 12 rises and the estimated refrigerant temperature also rises, regardless of the coolant temperature. Therefore, when the determination formula (2) is satisfied, it can be determined that the refrigerant is not flowing in water-refrigerant condenser 12, so that the electromagnetic valve 13 can be determined to be closed.
Air-conditioning controller 52 makes determination whether formula (1) and formula (2) are satisfied in the following cases. The first case is such that, from a state where electromagnetic valve 10 is opened and electromagnetic valve 13 is closed, electromagnetic valve 10 is switched to be closed and electromagnetic valve 13 is switched to be opened. The second case is such that, from a state where electromagnetic valve 10 is closed and electromagnetic valve 13 is opened, electromagnetic valve 10 is switched to be opened and electromagnetic valve 13 is switched to be closed. The third case is such that, from a state where both electromagnetic valves 10 and 13 are closed, electromagnetic valve 10 is switched to be opened and the operation of compressor 38 is started. The fourth case is such that, from a state where both electromagnetic valves 10 and 13 are closed, electromagnetic valve 13 is switched to be opened and the operation of compressor 38 is started. The fifth case is such that, in a state where it is supposed that electromagnetic valve 10 is opened and electromagnetic valve 13 is closed, the operation of compressor 38 is started. The sixth case is such that, in a state where it is supposed that electromagnetic valve 10 is closed and electromagnetic valve 13 is opened, the operation of compressor 38 is started. The opening or closing of electromagnetic valves 10 and 13 and the start of the operation of compressor 38 are executed after a command is issued from air-conditioning controller 52. If one or both of electromagnetic valves 10 and 13 has a fault, if is likely that both electromagnetic valves 10 and 13 are closed in the first to sixth cases. At this timing, whether formula (1) or (2) is satisfied or not is determined, whereby it can be determined that one of electromagnetic valves 10 and 13, which should be opened, is wrongly closed.
Next, the process for determining a fault in an electromagnetic valve will be described with reference to
In step ST201, air-conditioning controller 52 waits (time delay) until a predetermined time has elapsed. The reason for this is such that air-conditioning controller 52 waits until the refrigerant discharged from compressor 38 flows a little through outdoor condenser 39 or water-refrigerant condenser 12 and the pressure of the refrigerant is increased.
In step ST202, air-conditioning controller 52 acquires the pressure of the refrigerant from outdoor condenser 39, the pressure of the refrigerant from water-refrigerant condenser 12, the outside temperature, and the water temperature. The configuration for performing the process in step ST202 corresponds to a pressure acquisition unit and a temperature acquisition unit.
In step ST203, the refrigerant temperature is estimated based on the pressure of the refrigerant from outdoor condenser 39. In step ST204, the refrigerant temperature is estimated based on the pressure of the refrigerant from water-refrigerant condenser 12.
In step ST205, it is determined whether or not the relationship between the temperature of the refrigerant from outdoor condenser 39 and the outside temperature satisfies formula (1) and the relationship between the temperature of the refrigerant from water-refrigerant condenser 12 and the temperature of the coolant satisfies formula (2). The configuration for performing the process in stop S205 corresponds to a determination unit.
If the determination result in step S205 is YES, air-conditioning controller 52 proceeds to step ST206, and if the determination result in step S205 is NO, air-conditioning controller 52 ends the process for determining a fault in an electromagnetic valve.
In step ST206, air-conditioning controller 52 determines that both electromagnetic valves 10 and 13 are closed, and brings compressor 38 to an emergency stop. Accordingly, even when both, electromagnetic valves 10 and 13 are simultaneously closed due to a fault, an abnormal rise of the pressure of the refrigerant discharged from compressor 38 can be avoided.
As described above, according to the present exemplary embodiment, it is determined whether or not the value obtained by subtracting the outside temperature from the temperature of the refrigerant from outdoor condenser 39 is less than predetermined threshold K1, by using the detection result of first pressure sensor 16, which has low heat resistance property, and first temperature sensor 18, and based on this determination, it is determined whether or not the refrigerant is flowing through the refrigerant passage tor cooling. In addition, it is determined whether or not the value obtained by subtracting the coolant temperature from the temperature of the refrigerant from water refrigerant condenser 12 is less than predetermined threshold K2, by using the detection result of second pressure sensor 17, which has low heat resistance property and second temperature sensor 19. Based on the determination results, it can be determined whether or not the refrigerant is flowing through the refrigerant passage for heating or through the refrigerant passage for cooling, and thus, a fault, in the electromagnetic valve can be determined with reduced cost without the need of an expensive component. In addition, when it is determined that two electromagnetic valves are simultaneously closed, the operation of the compressor is stopped, whereby the damage of a system including the compressor can be avoided.
Note that the present disclosure is not limited to the configuration and method specifically described in the exemplary embodiment. For example, the above-mentioned exemplary embodiment indicates the process for determining a fault in an electromagnetic valve to detect an abnormal condition in which two electromagnetic valves 10 and 13 located on the discharge port of compressor 38 are both closed. However, the present disclosure may be applied to a process for determining, when a command to switch one electromagnetic valve 10 (or electromagnetic valve 13) from a closed state to an open state is issued, whether the target valve is normally brought into the open state.
In addition, the exemplary embodiment indicates the outdoor condenser using air as a first heating medium as the first heat exchanger that exchanges heat between a refrigerant and the first heating medium, and the water-refrigerant condenser using a coolant as a second heating medium as the second heat exchanger that exchanges heat between the coolant and the second heating medium. However, both the first heat exchanger and the second heat exchanger may be configured to exchange heat between a refrigerant and air, or both may be configured to exchange heat between a refrigerant and a coolant.
In addition, the exemplary embodiment illustrates, in the drawing, one example of a pattern of a refrigerant passage and a pattern of a coolant, passage. However, the present, disclosure is similarly applicable to an air-conditioning device having various patterns of a refrigerant passage and various patterns of a coolant passage.
The vehicle air conditioning device according to the present disclosure is applicable to a vehicle, such as an automobile, including an internal combustion engine.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-222794 | Oct 2014 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2015/005294 | Oct 2015 | US |
| Child | 15486485 | US |
