JP2012081888A - Air conditioner control device for vehicle and control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for improving fuel economy in the control of an air conditioner during idling.SOLUTION: This air conditioner control device for a vehicle controls an air conditioner comprising a compressor driven by a heat engine for a vehicle and an evaporator for evaporating refrigerant so that the cooling performance of the air conditioner can approach the given target cooling performance. The air conditioner control device for a vehicle includes a cooling performance detection part for detecting the cooling performance of the air conditioner, a target rotational speed determination part which compares the detected cooling performance with the target cooling performance and determines the target rotational speed of the heat engine for a vehicle so that the detected cooling performance approaches the target cooling performance, and an operation mode changeover part which sets the air conditioner to a continuous operation mode when the target rotational speed is larger than a preset determination value and to an on/off operation mode when the determined target rotational speed is smaller than the determination value.

Description

  The present invention relates to a vehicle including an air conditioner configured to include a compressor that is driven by power of a vehicle heat engine and compresses a refrigerant, and more particularly to a vehicle air conditioning control device that controls the air conditioner.

  2. Description of the Related Art Conventionally, there has been proposed a control method for improving fuel efficiency during idling of an internal combustion engine in a vehicle air-conditioning control apparatus that drives a compressor that compresses refrigerant by the power of the internal combustion engine. Specifically, for example, Patent Document 1 proposes a technique for switching the idling rotational speed of an internal combustion engine to one of a plurality of preset rotational speeds according to the load of the air conditioner. In Patent Documents 2 to 5, a technique is proposed in which a thermal load is estimated based on measured values such as compressor operating time, discharge pressure, or inside / outside air temperature, and the idling speed is controlled based on the estimated value. In Patent Document 6, in the on / off operation of the compressor, a thermal load is estimated based on a room temperature change speed when the compressor is on, and when the estimated thermal load is small, a technique for prohibiting idle-up when the compressor is on Has also been proposed.

JP-A-6-99726 JP-A-6-229273 JP-A-57-181942 JP-A-62-111138 JP 2006-336479 A JP-A-6-101515 JP 2001-270323 A

  However, each of the above-described techniques has been limited to improving each part of the control system of the vehicle air conditioning control device. In response to this, the present inventor has found that there is room for improvement by reviewing the entire control system of the vehicle air conditioning control device, or the entire vehicle air conditioning control device and the internal combustion engine control device. On the other hand, an expansion valve for stabilizing the degree of refrigerant superheating as the temperature of the refrigerant flowing out of the evaporator of the air conditioner is widespread (Patent Document 7). However, since the stability of the refrigerant superheat is achieved by reducing the flow rate of the refrigerant while the engine speed is fixed, the present inventor has found that excessive energy loss has occurred in the engine. It was done.

  The present invention was created to solve the above-described conventional problems, and an object of the present invention is to provide a technique for improving fuel efficiency in controlling an air conditioner during idling.

  Hereinafter, effective means for solving the above-described problems will be described while showing effects and the like as necessary.

  The invention of claim 1 is an air conditioning control device for a vehicle that controls the air conditioning device having a compressor driven by a vehicle heat engine and an evaporator for vaporizing a refrigerant so as to approach a given target air conditioning capability. Then, the cooling capacity detection unit that detects the cooling capacity of the air conditioner is compared with the detected cooling capacity that is the detected cooling capacity and the target cooling capacity, and the detected cooling capacity approaches the target cooling capacity. As described above, the target rotational speed determination unit that determines the target rotational speed of the vehicle heat engine, and when the target rotational speed is greater than a preset determination value, the air conditioner is set to a continuous operation mode and the determined And an operation mode switching unit that sets the operation mode of the air conditioner to an on / off operation mode when the target rotational speed is smaller than the determination value.

  According to the above invention, when the target rotational speed of the vehicle engine determined according to the target cooling capacity is higher than a predetermined determination value, the cooling capacity can be operated by adjusting the idling rotational speed. In addition, energy loss due to on / off of the compressor drive can be suppressed. On the other hand, when an idling speed equal to or lower than the determination value is required according to the target cooling capacity, the compressor can be appropriately cooled by turning on / off the compressor drive.

  According to a second aspect of the present invention, the vehicle air conditioning control device further includes a discharge pressure measuring unit that measures a discharge pressure of the compressor, transmits the measured discharge pressure to the vehicle heat engine, and determines the determination value. Is determined by the vehicle heat engine using the measured discharge pressure.

  According to the above invention, since the determination value is determined using the discharge pressure of the compressor, the driving torque of the vehicle heat engine applied to the compressor can be estimated. As a result, it is possible to set a determination value that takes into account the driving torque of the compressor. Therefore, the frequency of the on / off operation mode can be reduced by decreasing the determination value in accordance with a decrease in the driving torque. As a result, it is possible to suppress energy loss due to on / off of the compressor drive.

  According to a third aspect of the present invention, the target rotation speed determination unit includes a superheat degree detection unit that detects a refrigerant superheat degree that is a temperature of the refrigerant that has flowed out of the evaporator, and the target rotation number determination part includes the superheat degree detection unit according to the detected refrigerant superheat degree. The target rotational speed is adjusted.

  According to the above invention, the target rotational speed can be adjusted in accordance with the degree of refrigerant superheat, so that the refrigerant supply amount can be followed quickly with respect to fluctuations in the cooling load. Thereby, for example, it is possible to provide a degree of design freedom such as elimination of the expansion valve or simplification of the configuration of the expansion valve, or a degree of design freedom of reducing the storage capacity of the receiver (gas-liquid separator).

  The invention according to claim 4 is characterized in that the target rotational speed determination unit reduces the target rotational speed in accordance with the detected decrease in the degree of refrigerant superheat.

  According to the above invention, it is possible to quickly detect the surplus state of the refrigerant supply and reduce the target rotational speed. Thereby, a fuel consumption can be improved effectively.

  According to a fifth aspect of the present invention, there is provided a vehicle control device for controlling a vehicle heat engine and an air conditioner, wherein the vehicle air condition control device and the number of revolutions of the vehicle heat engine are controlled to control idling. A vehicle heat engine control unit that determines the minimum rotation speed of the vehicle as the determination value and transmits the determination value to the vehicle air conditioning control device. The vehicle heat engine control unit controls the idling rotation speed of the vehicle heat engine with the target rotation speed as a target value when the target rotation speed is greater than the determination value, and the target rotation speed is the determination value. In the following cases, the idling rotational speed of the vehicle heat engine is controlled using the minimum rotational speed as a target value.

  According to the fifth aspect of the present invention, it is possible to efficiently control the air conditioner while ensuring the reliability of the operation of the vehicle heat engine by cooperative control of the vehicle heat engine and the air conditioner. In this cooperative control, the vehicle heat engine transmits the minimum number of revolutions of idling control as a determination value to the vehicle air conditioning control device. The vehicle air-conditioning control device can know the range of idling rotation speeds that can be continuously operated from the given determination value.

  Thus, in the range of idling rotation speeds that can be continuously operated, the vehicle air conditioning control device can operate the target rotation value of the vehicle heat engine to operate the output of the air conditioning device, while the vehicle air conditioning control device Therefore, efficient operation can be realized by executing on / off control when the target rotational speed is equal to or lower than the determination value.

  The invention according to claim 6 is characterized in that the determination value is determined using a heat engine state quantity including at least one of engine water temperature and ignition timing of the vehicle heat engine.

  According to the above invention, since the determination value is determined using the heat engine state quantity including at least one of the engine water temperature and the ignition timing of the vehicle heat engine, the output torque of the vehicle heat engine caused by warm air is determined. The frequency of the on / off operation mode can be reduced by decreasing the determination value in accordance with the completion of the decrease.

  According to a seventh aspect of the present invention, there is provided an air conditioning control apparatus for a vehicle that controls the air conditioning apparatus having a compressor driven by a vehicle heat engine and an evaporator that vaporizes a refrigerant so as to approach a given target cooling capacity. Then, the cooling capacity detection unit that detects the cooling capacity of the air conditioner is compared with the detected cooling capacity that is the detected cooling capacity and the target cooling capacity, and the detected cooling capacity approaches the target cooling capacity. As described above, a target rotational speed determination unit that determines a target rotational speed of the vehicle heat engine is provided. The target rotational speed determination unit includes a superheat degree detection unit that detects a refrigerant superheat degree that is a temperature of the refrigerant that has flowed out of the evaporator, and adjusts the target rotational speed according to the detected refrigerant superheat degree. It is characterized by.

  According to the above invention, the target rotational speed can be adjusted in accordance with the degree of refrigerant superheat, so that the refrigerant supply amount can be followed quickly with respect to fluctuations in the cooling load. The above-described invention can be implemented even in a configuration that does not switch between continuous operation and on / off control based on the determination value. However, switching based on the judgment value can provide a degree of freedom in design that widens the range of continuous operation (idling speed range), so the adjustment range of the target speed according to the degree of refrigerant superheat is also widened and remarkable. Can produce various effects.

  The present invention can be embodied not only in a vehicle air conditioning control device but also in the form of, for example, a computer program that embodies a control method and a control function, a program medium that stores the program, or a program product.

1 is an overall configuration diagram showing configurations of an internal combustion engine system 10 and an air conditioning control device 50 according to a first embodiment. The flowchart which shows the routine of the air-conditioning control of embodiment. The time chart which shows the mode of an action | operation of the air-conditioning control apparatus 50. FIG. The whole block diagram which shows the structure of the internal combustion engine system 10 and air-conditioning control apparatus 50a concerning 2nd Embodiment. The time chart which shows the operating state of the air-conditioning control apparatus 50a concerning 2nd Embodiment. The chart which compares and shows the adjustment range of the idling rotation speed of embodiment and a modification.

  Hereinafter, two embodiments in which a vehicle air conditioning control device according to the present invention is applied to a vehicle (automobile) equipped with an internal combustion engine will be described with reference to the drawings.

(First embodiment)
FIG. 1 is an overall configuration diagram showing configurations of an internal combustion engine system 10 and a vehicle air conditioning control device 50 (air conditioner system) according to the first embodiment. The internal combustion engine system 10 includes an engine 11 as a control target and an engine ECU 12 as a control device. The air conditioning system includes an air conditioner 20 as a control target and an air conditioner control device 50 as a control device. The air conditioner 20 includes a compressor 21, a condenser 22, a receiver 23, an expansion valve 24, and an evaporator 25. The engine 11 is also called a vehicle heat engine. The engine ECU 12 is also referred to as a vehicle heat engine control unit. The vehicle air conditioning control device 50 is also called an air conditioning control device.

  The compressor 21 is a constant capacity compressor that sucks the refrigerant gas evaporated by the evaporator 25 and pressurizes the refrigerant gas so as to be easily liquefied by the condenser 22. The compressor 21 is driven by the engine 11. Transmission of the driving force is carried out by a pulley 26 mechanically connected to the drive shaft of the compressor 21, a pulley 27 mechanically connected to the crankshaft 14 of the engine 11 via a clutch 57a, two pulleys 26, 27 and the belt 28 connecting the belt 27. The connection and disconnection of the clutch 57a are operated by the air conditioner ECU 59.

  The state quantity of the compressor 21 includes a suction pressure that is a pressure at which the compressor 21 sucks refrigerant and a discharge pressure that is a pressure at which the compressor 21 discharges refrigerant. The required torque (drive torque) of the compressor 21 can be estimated according to the difference between the discharge pressure and the suction pressure. The compressor 21 can also use a variable displacement configuration. However, this embodiment has a remarkable effect that the cooling capacity can be operated by adjusting the rotation speed in a constant displacement compressor.

  The condenser 22 is a condenser that liquefies the pressurized gaseous refrigerant supplied from the compressor 21. The refrigerant is liquefied by performing heat exchange (air cooling) between the pressurized refrigerant discharged from the compressor 21 and air blown from a fan (not shown) or air blown to the condenser 22 as the vehicle travels. Is called.

  The receiver 23 is a gas-liquid separator that separates the liquid-phase refrigerant from the two-phase refrigerant of liquid and gas by the condenser 22 and supplies the separated refrigerant to the evaporator 25. Separation of the liquid phase refrigerant is performed by sending the refrigerant through a pipe whose tip is submerged in the liquid refrigerant stored in the receiver 23. The receiver 23 also has a liquid refrigerant storage function. Supply of the high-pressure liquid refrigerant to the evaporator 25 is performed via the expansion valve 24.

  The evaporator 25 is a device that takes heat away by vaporizing the refrigerant. The evaporator 25 is provided with an evaporator fan 55d for introducing indoor or outdoor air and sending cool air into the vehicle interior. The evaluation fan 55d can lower the room temperature by sending cold air into the passenger compartment. The state quantity of the evaporator 25 includes an evaporator inlet temperature that is the temperature of the air before the heat exchange in the evaporator 25 and an evaporator outlet temperature that is the temperature of the air after the heat exchange in the evaporator 25.

  The expansion valve 24 is a kind of throttle valve, and can generate a pressure difference between the receiver 23 and the evaporator 25. The expansion valve 24 can further expand the high-pressure liquid refrigerant into a low-pressure / low-temperature mist by blowing out the high-pressure liquid refrigerant from a small gap and expanding the refrigerant. Thereby, the low-pressure and low-temperature mist-like refrigerant enables rapid vaporization in the evaporator 25.

  The expansion valve 24 has a function as an automatic adjustment valve that mechanically adjusts the opening according to the degree of refrigerant superheat. For example, as disclosed in paragraph 0002 of Patent Document 7, the automatic adjustment of the opening degree draws the refrigerant flow path on the outlet side of the evaporator 25 into the expansion valve 24 and is sealed in the internal space by the heat of the refrigerant. This can be realized by moving the valve body by thermally expanding the gas being heated.

  The air conditioning control device 50 includes an air conditioner ECU 59, a plurality of sensors 53, 54, 56, 57, 58 for setting the cooling capacity, and a plurality of sensors 51a, 51b, 55a, 55b. The air conditioner ECU 59 is an electronic control device that controls the air conditioner 20, and includes a well-known CPU, ROM, RAM, and the like. The air conditioner ECU 59 has a function of setting a target cooling capacity using a plurality of sensors 53, 54, 56, 57, and 58 and a function of operating the air conditioner 20 using the target cooling capacity Pt (kW) as a target value. is doing. The air conditioner ECU 59 controls the air conditioner 20 while measuring the state quantity of the air conditioner 20 with the plurality of sensors 51a, 51b, 55a, 55b.

  FIG. 2 is a flowchart illustrating a routine of air conditioning control according to the embodiment. This routine is started in response to an ON operation of the A / C switch 52. The air conditioner ECU 59 starts driving the compressor 21 with the clutch 57a in a connected state in response to the actual activation, and starts receiving detection signals from the plurality of sensors 51a, 51b, 55a, 55b.

  In step S10, the air conditioner ECU 59 executes a target performance setting process. The target performance setting step is a step of setting the target cooling capacity Pt of the air conditioner 20. In the present embodiment, the target cooling capacity Pt means the amount of heat that should be exchanged by the evaporator 25 per time. The target cooling capacity Pt is set using the vehicle interior temperature, the outside air temperature, the humidity, the amount of solar radiation, and the traveling speed of the vehicle. The vehicle interior temperature is measured by the room temperature sensor 53. The temperature of the outside air is detected by the outside air temperature sensor 58. The humidity of the outside air is detected by the humidity sensor 54. The amount of solar radiation is detected by the solar radiation sensor 56. The traveling speed of the vehicle is detected by a vehicle speed sensor 57.

  In step S20, the air conditioner ECU 59 executes a cooling capacity detection process. The cooling capacity detection process is a process of detecting the actual detection cooling capacity Pd (kW) of the air conditioner 20. The detected cooling capacity Pd is detected as a measured value of the heat exchange amount by the evaporator 25. This measured value is measured based on the difference between the inlet temperature and the outlet temperature. The evaporator inlet temperature is detected by the inlet temperature detection sensor 55a. The exhaust outlet temperature is detected by the outlet temperature detection sensor 55b.

  In step S30, the air conditioner ECU 59 executes a target rotational speed determination step. The target rotational speed determination step is a step of determining the target rotational speed Nr of the compressor 21. The target rotation speed Nr is a rotation speed determined so that the detected cooling capacity Pd (kW) approaches the target cooling capacity Pt according to a control law of the air conditioner ECU 59. In this way, the air conditioner ECU 59 functions as a target rotational speed determination unit.

  In step S40, the air conditioner ECU 59 determines whether or not the target rotation speed Nr is larger than the determination value Th. The determination value Th is a calculated value of the rotation speed of the compressor 21 at the minimum rotation speed Nm of the crankshaft 14 of the engine 11. This calculated value is calculated using the rotation ratio of the two pulleys 26 and 27 and the minimum rotation speed Nm. The minimum rotational speed Nm is a value given from the engine ECU 12 included in the internal combustion engine system 10.

  The minimum rotational speed Nm is set as the minimum rotational speed for maintaining the drive of the engine 11, for example. That is, the minimum rotation speed Nm is set as the minimum rotation speed at which engine stall of the engine 11 does not occur. The minimum engine speed Nm is set by the engine ECU 12 based on, for example, the engine water temperature, the ignition timing, and the load torque Q of the compressor 21. The load torque Q of the compressor 21 is a torque as a load that the compressor 21 applies to the crankshaft 14 of the engine 11. The minimum rotational speed Nm is set higher when the load torque Q is large.

  The load torque Q is determined by the air conditioner ECU 59 according to the amount of pressurization of the compressor 21. The air conditioner ECU 59 calculates the amount of pressurization based on the difference between the discharge pressure sensor 51b and the suction pressure sensor 51a of the compressor 21, and estimates the load torque Q using the calculated value. The estimation of the load torque Q is performed using a preset correspondence curve or an estimation calculation formula. The load torque Q is transmitted from the air conditioner ECU 59 to the engine ECU 12 in real time.

  The engine water temperature is used to confirm the completion of warm-up, and the minimum rotational speed Nm is set higher until the warm-up is completed. Information about the ignition timing is used to increase the minimum rotation speed Nm when the ignition timing is late. This is because when the ignition timing is late, engine stall is likely to occur due to a decrease in torque. The ignition timing delay is intended to quickly raise the catalyst temperature by raising the exhaust gas temperature during warm-up, thereby quickly raising the exhaust gas purification capability.

  As a result of the comparison determination in step S40, if the target rotation speed Nr is larger than the determination value Th, the process proceeds to step S50. If the target rotation speed Nr is equal to or less than the determination value Th, the process proceeds to step S60. It is done.

  In step S50, the air conditioner ECU 59 sets the operation mode of the air conditioner 20 to the continuous operation mode. The continuous operation mode is an operation mode in which the compressor 21 is controlled to approach the target rotational speed Nr by operating the idling rotational speed Ni of the engine 11 while maintaining the clutch 57a in the connected state. In the continuous operation mode, the air conditioner ECU 59 maintains the clutch 57a in the connected state and transmits the target rotational speed Nr to the engine ECU 12. That is, in the continuous operation mode, the disengagement of the clutch 57a is restricted (including prohibition). On the other hand, the engine ECU 12 adjusts the idling rotational speed Ni so that the compressor 21 approaches the target rotational speed Nr.

  In step S60, the air conditioner ECU 59 sets the operation mode of the air conditioner 20 to the on / off operation mode. The on / off mode is an operation mode in which the cooling capacity of the air conditioner 20 is operated by switching the clutch 57a between connection and disconnection. The idling rotational speed Ni is fixed to the minimum rotational speed Nm in this embodiment.

  The switching operation is turned on when the preset on-threshold temperature is exceeded, for example, according to the measured value of the room temperature sensor 53 (the clutch 57a is connected), and the off operation (clutch is not more than the preset off-threshold temperature). 57a is not connected). Hysteresis is provided by setting the on threshold temperature higher than the off threshold temperature.

  As described above, the air-conditioning control device 50 according to the present embodiment is higher than the minimum rotation speed Nm when the rotation higher than the minimum rotation speed Nm that is the minimum rotation speed for maintaining the drive of the engine 11 is requested. The output of the air conditioner 20 can be continuously controlled in the range of high rotational speed. On the other hand, the air-conditioning control device 50 of the present embodiment can execute on / off control when the air-conditioning device 20 is driven at the minimum rotational speed Nm and the cooling capacity becomes excessive.

  FIG. 3 is a time chart showing how the air conditioning control device 50 operates. The target cooling capacity is expressed by the height of the line as the size of the target cooling capacity Pt. The target compressor speed is expressed as a line height as the target engine speed Nr of the compressor 21. The engine target speed is a target value of the idling speed Ni determined using the target speed Nr of the compressor 21. The air conditioner ON / OFF state indicates a switching state between the ON state (the clutch 57a is connected) and the OFF state (the clutch 57a is not connected) in the on / off operation mode.

  On the other hand, the determination value Th is a value determined by the ignition timing, the engine water temperature, and the load torque Q of the compressor 21 in this example. The minimum rotation speed Nm is a value calculated from the determination value Th.

  At time t1, the air conditioner ECU 59 decreases the compressor target rotational speed as the target cooling capacity decreases. The engine ECU 12 reduces the target engine speed as the compressor target speed Nr given from the air conditioner ECU 59 decreases. However, the ON state of the air conditioner continues. The target cooling capacity Pt is reduced due to, for example, a temperature drop in the passenger compartment. In this state, since the compressor target rotational speed Nr is a value larger than the determination value Th, the air conditioner 20 is controlled in the continuous operation mode (steps S40 and S50).

  At the time t2, the compressor target rotational speed Nr is decreased in accordance with the decrease of the target cooling capacity Pt again. However, the engine ECU 12 operates the idling speed Ni so that the compressor 21 approaches the minimum speed Nm. That is, the engine ECU 12 overrides the request for the compressor target rotational speed Nr and uses the minimum rotational speed Nm as the target value for the idling rotational speed Ni. On the other hand, the air conditioner ECU 59 switches the air conditioner to the OFF state by disengaging the clutch 57a. In this state, since the compressor target rotation speed Nr is a value equal to or less than the determination value Th, the air conditioner 20 is controlled in the on / off operation mode (steps S40 and S60).

  At the time t3, the compressor target rotational speed Nr is decreased in accordance with the decrease of the target cooling capacity Pt again. However, the engine ECU 12 operates the idling rotational speed Ni so that the compressor 21 continues to approach the minimum rotational speed Nm from time t2. In this state, the duty (time ratio) of the ON time of the air conditioner 20 is lower than that at the time t2 to t3. Thus, in the on / off operation mode, the cooling capacity is operated by the duty of the on time.

  At time t4, the air conditioner ECU 59 increases the target compressor speed in accordance with the increase in the target cooling capacity, and switches the air conditioner to the ON state with the clutch 57a connected. The engine ECU 12 increases the target engine speed as the compressor target speed given from the air conditioner ECU 59 increases. The increase in the target cooling capacity occurs when outside air enters the vehicle interior (not shown) by opening a vehicle door (not shown), for example.

  At time t4, the air conditioner ECU 59 restricts the disconnected state of the clutch 57a again. That is, in the continuous operation mode, the operation of the cooling capacity can be performed by operating the engine target speed while the connected state is maintained even when the room temperature is equal to or lower than the off-threshold temperature, that is, when the clutch 57a reaches the disengaged temperature. Done. Such an operation mode is called a continuous operation mode.

  At time t5, the determination value Th decreases. The decrease in the determination value Th occurs due to, for example, the end of the ignition timing delay due to the completion of the catalyst temperature increase, the completion of the warm-up state due to the engine water temperature, and the decrease in the load torque Q of the compressor 21. Note that the minimum rotation speed Nm is a value proportional to the determination value Th, and therefore decreases with the determination value Th.

  At time t6, the air conditioner ECU 59 decreases the target compressor speed Nr as the target cooling capacity Pt decreases. The engine ECU 12 reduces the target engine speed as the compressor target speed Nr given from the air conditioner ECU 59 decreases. However, the idling rotational speed Ni is lowered to a value lower than the determination value Th at times t1 to t4. This is because the state in which the determination value Th has decreased continues at time t5.

  At time t7, the air conditioner ECU 59 reduces the target compressor speed Nr as the target cooling capacity decreases again. However, the engine ECU 12 overrides the request for the compressor target rotational speed Nr and uses the minimum rotational speed Nm that has decreased at time t5 as the target value for the idling rotational speed Ni.

  As described above, in the first embodiment, when the idling speed Ni higher than the minimum speed Nm of the engine 11 is required according to the target cooling capacity, the cooling capacity is operated by adjusting the idling speed Ni. Therefore, energy loss due to the on / off of the drive of the compressor 21 can be suppressed.

  On the other hand, when the idling speed Ni of the minimum speed Nm or less is required according to the target cooling capacity, the compressor 21 can be appropriately cooled by turning on / off the drive while maintaining the minimum speed Nm. In this embodiment, the minimum rotational speed Nm is set appropriately by monitoring state quantities such as ignition timing, engine water temperature, and load torque Q of the compressor 21, that is, it can be reduced. It has also succeeded in suppressing the range to become.

(Second Embodiment)
FIG. 4 is an overall configuration diagram showing configurations of the internal combustion engine system 10 and the air conditioning control device 50a according to the second embodiment. The air conditioning control device 50a is different from the air conditioning control device 50 of the first embodiment in the following two points, and has other configurations in common. The first difference is that the mechanically controlled expansion valve 24 is changed to an electronically controlled expansion valve 24a. The second difference is that a refrigerant superheat sensor 55c is provided. The refrigerant superheat degree sensor 55 c measures the refrigerant temperature in the refrigerant flow path on the outlet side of the evaporator 25. The opening degree of the electronically controlled expansion valve 24 a is adjusted by a command from the air conditioner ECU 59.

  FIG. 5 is a time chart showing an operating state of the air conditioning control device 50a according to the second embodiment. This time chart shows the control contents of the comparative example and the second embodiment when the user raises the set temperature while the A / C switch 52 is in the ON state. In the comparative example, a mechanically controlled expansion valve 24 is used. When the user increases the set temperature, the blower level (air flow rate) of the eva fan 55d is decreased in both the comparative example and the control of the second embodiment.

  The degree of refrigerant superheat decreases due to a decrease in the blower level of the EVA fan 55d. This is because when the blower level of the evaporator fan 55d decreases, the amount of heat exchange in the evaporator 25 decreases and the temperature rise of the refrigerant decreases. In the comparative example, the mechanically controlled expansion valve 24 automatically throttles the valve opening as the refrigerant temperature decreases in the refrigerant flow path on the outlet side of the evaporator 25. As a result, the amount of refrigerant supplied to the evaporator 25 decreases, and the degree of refrigerant superheat returns to an appropriate value. However, in the comparative example, the rotational speed of the engine 11 and the rotational speed of the compressor 21 are maintained even though the supply amount of the refrigerant to the evaporator 25 is decreased.

  On the other hand, in the second embodiment, while the electronically controlled expansion valve 24a maintains the opening degree, the rotational speed of the engine 11 decreases and the refrigerant discharge amount of the compressor 21 decreases. As a result, the surplus state of the refrigerant supply can be quickly detected and the target rotational speed can be reduced, so that the fuel consumption corresponding to the decrease in the rotational speed of the engine 11 is reduced and the fuel efficiency is improved.

  Furthermore, for example, it is possible to provide a degree of freedom in design such as elimination of the expansion valve 24 or simplification of the configuration of the expansion valve 24 or a degree of design in which the storage capacity of the receiver 23 (gas-liquid separator) is reduced. Simplification of the configuration of the expansion valve 24 can, for example, relax accuracy specifications.

(Other embodiments)
The embodiment is not limited to the above contents, and may be implemented as follows, for example.

  In the above embodiment, the minimum rotational speed Nm is set according to the load torque Q of the compressor 21, but the minimum rotational speed is determined according to at least one of the ignition timing and the engine water temperature without using the load torque Q, for example. You may comprise as a modification which sets Nm. However, the above-described embodiment has the advantage that the frequency of the compressor on / off control is reduced by using the load torque Q, and thereby the energy loss due to the compressor on / off can be made smaller than the configuration of the modified example. Have.

  FIG. 6 is a chart showing a comparison of the adjustment range of the idling rotational speed of the embodiment and the modified example. In the embodiment, the rotational speed of the engine 11 can be reduced to the rotational speed N2 without performing on / off control of the compressor 21. That is, in the embodiment, since the minimum rotation speed Nm is set to the rotation speed N2, the operation range A1 is realized as an adjustment range of the idling rotation speed. On the other hand, in the modified example, since the rotation speed that can be reduced without performing the on / off control of the compressor 21 is the rotation speed N3, the adjustment range of the idling rotation speed is limited to the operation range A2. Since the compressor discharge pressure is not measured, the rotation speed N3 cannot be used as the load torque Q, and is set as the maximum value of the load torque Q in a preset operation range.

  However, even in the modified example, since the minimum rotation speed Nm is set according to at least one of the ignition timing and the engine water temperature, the advantage of improving the energy efficiency can be obtained by expanding the adjustment range of the idling rotation speed to the low rotation side. . In the on / off control of the compressor 21, the rotation speed N4 at which engine stall does not occur due to the shock of coupling of the clutch 57a and the rotation speed N1 that is the minimum rotation speed that can be stably idled when the clutch 57a is disconnected are alternately alternated. The number of revolutions is controlled to reciprocate.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine system, 11 ... Engine, 12 ... Engine ECU, 20 ... Air conditioner, 21 ... Compressor, 22 ... Condenser, 23 ... Receiver, 24, 24a ... Expansion valve, 25 ... Evaporator, 26, 27 ... Pulley, 28 ... belt, 50, 50a ... air conditioning control device, 55d ... EVA fan, 56 ... solar radiation sensor, 57 ... vehicle speed sensor.

Claims (7)

An air conditioning control device for a vehicle that controls a cooling capability of an air conditioning device having a compressor driven by a vehicle heat engine and an evaporator that vaporizes a refrigerant so as to approach a given target cooling capability,
A cooling capacity detector that detects the cooling capacity of the air conditioner;
The target cooling speed for comparing the detected cooling capacity, which is the detected cooling capacity, with the target cooling capacity and determining the target rotational speed of the vehicle heat engine so that the detected cooling capacity approaches the target cooling capacity. A decision unit;
When the target rotational speed is larger than a predetermined determination value, the air conditioner is set in a continuous operation mode. When the determined target rotational speed is smaller than the determination value, the operation mode of the air conditioner is set as an on / off operation mode. An operation mode switching unit to
A vehicle air-conditioning control device comprising: The vehicle air conditioning control device further includes a discharge pressure measuring unit that measures the discharge pressure of the compressor, and transmits the measured discharge pressure to the vehicle heat engine,
The vehicle air conditioning control device according to claim 1, wherein the determination value is determined by the vehicle heat engine using the measured discharge pressure.   The target rotation speed determination unit includes a superheat degree detection unit that detects a refrigerant superheat degree that is a temperature of the refrigerant that has flowed out of the evaporator, and adjusts the target speed according to the detected refrigerant superheat degree. Item 3. The vehicle air conditioning control device according to Item 1 or 2.   The vehicle air conditioning control device according to claim 3, wherein the target rotational speed determination unit reduces the target rotational speed in accordance with a decrease in the detected refrigerant superheat degree. A vehicle control device for controlling a vehicle heat engine and an air conditioner,
The vehicle air-conditioning control device according to any one of claims 1 to 4,
A vehicle heat engine controller that controls the number of revolutions of the vehicle heat engine, determines a minimum number of revolutions of idling control as the determination value, and transmits the determination value to the vehicle air conditioning control device;
With
The vehicle heat engine control unit controls the idling rotation speed of the vehicle heat engine with the target rotation speed as a target value when the target rotation speed is greater than the determination value, and the target rotation speed is the determination value. In the following cases, the vehicle control apparatus controls the idling rotation speed of the vehicle heat engine with the minimum rotation speed as a target value.   The vehicle control device according to claim 5, wherein the determination value is determined using a heat engine state quantity including at least one of an engine water temperature and an ignition timing of the vehicle heat engine. An air conditioning control device for a vehicle that controls a cooling capability of an air conditioning device having a compressor driven by a vehicle heat engine and an evaporator that vaporizes a refrigerant so as to approach a given target cooling capability,
A cooling capacity detector that detects the cooling capacity of the air conditioner;
The target cooling speed for comparing the detected cooling capacity, which is the detected cooling capacity, with the target cooling capacity and determining the target rotational speed of the vehicle heat engine so that the detected cooling capacity approaches the target cooling capacity. A decision unit;
With
The target rotational speed determination unit includes a superheat degree detection unit that detects a refrigerant superheat degree that is a temperature of the refrigerant that has flowed out of the evaporator, and adjusts the target rotational speed according to the detected refrigerant superheat degree. A vehicle air-conditioning control device.

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