JP2019010913A - Air conditioner for vehicle - Google Patents

Abstract

To provide an air conditioner for a vehicle capable of eliminating wasting of power.SOLUTION: An air conditioner 1 for a vehicle includes: a compressor 2 having a compression mechanism for compressing a refrigerant accompanying the rotation of a compression rotary shaft 2s; a magnet clutch 21 for connecting a compressor pulley 20 that rotates by the power of an engine 9, to the compression rotary shaft 2s as needed; a pressure detector 3 for detecting the pressure of the refrigerant compressed by the compressor 2; and a control part 4 for controlling the operation of the magnet clutch 21 by a predetermined applied voltage. The control part 4 includes a voltage derivation part 40 for obtaining the applied voltage required to transmit the torque of the compressor pulley 20 to the compression rotary shaft 2s and rotate the compression rotary shaft 2s based on the result of the detection by the pressure detector 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicle air conditioner that can reduce waste of electric power.

  The vehicle air conditioner includes a heat exchange system that warms the conditioned air and a heat exchange system that cools the conditioned air. The heat exchange system that cools the air-conditioning air includes an evaporator that cools the air-conditioning air, a compressor having a compression mechanism that compresses the refrigerant as the compression rotation shaft rotates, a condenser that cools the refrigerant compressed by the compressor, and a refrigerant that has passed through the condenser. An expansion valve for spraying the circulation path in the evaporator is provided.

  The operation of the compressor is sometimes performed by electricity, but often uses the rotational power of the engine. For example, the vehicle air conditioners disclosed in Patent Documents 1 and 2 adopt a configuration using a magnet clutch that connects a compressor pulley that rotates in conjunction with a crankshaft via a belt to a compression rotating shaft as necessary. Furthermore, Patent Document 1 describes a configuration in which the pressure of refrigerant compressed by a compressor is detected and the compressor is stopped based on the detection result. Patent Document 2 describes a configuration in which a cooling fan that cools a condenser is stopped based on a detection result of refrigerant pressure.

Japanese Patent Laid-Open No. Sho 62-158947 JP2013-199245A

  In the conventional configuration, when the magnet clutch is turned on, a certain maximum voltage is applied to the magnet clutch, and unnecessary power is consumed. For example, when the refrigerant pressure is not so high, the torque required to rotate the compression rotation shaft of the compressor may be small. In that case, even if the voltage applied to the magnet clutch is lower than the maximum voltage, the magnet clutch will not slip and the compressor pulley will not run idle, and power is wasted by the difference between the maximum voltage and the actually required applied voltage. It can be said that

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vehicle air conditioner that can reduce waste of electric power.

An air conditioner for a vehicle according to an aspect of the present invention provides:
A compressor having a compression mechanism for compressing the refrigerant with rotation of the compression rotation shaft;
A magnet clutch that connects a compressor pulley that rotates with the power of the engine to the compression rotation shaft as required;
A pressure detector for detecting the pressure of the refrigerant compressed by the compressor;
A vehicle air conditioner comprising: a control unit that controls the operation of the magnet clutch with a predetermined applied voltage;
The control unit includes a voltage deriving unit that obtains the applied voltage necessary to rotate the compression rotating shaft by transmitting torque of the compressor pulley to the compression rotating shaft based on a detection result of the pressure detector. Prepare.

As one form of the vehicle air conditioner which concerns on 1 aspect of this invention,
The controller is
An operation determining unit that determines whether or not the pressure of the refrigerant according to the rotational speed of the engine is obtained;
A mode in which the applied voltage is corrected or the magnet clutch is stopped according to the determination result of the operation determination unit can be mentioned.

  According to the vehicle air conditioner described above, a variable voltage that can transmit the torque of the compressor pulley to the compression rotating shaft is applied to the magnet clutch in accordance with the pressure of the refrigerant, so that waste of electric power accompanying the cooling operation is reduced. Can do.

  By determining whether or not the refrigerant pressure corresponding to the engine speed is obtained, it is possible to grasp the idling of the compressor pulley, the compressor failure, etc., and take necessary measures. For example, the applied voltage is corrected so that the torque of the compressor pulley can be transmitted to the compression rotating shaft. If no increase in the refrigerant pressure is recognized even when the magnet clutch is operated at the maximum voltage, it is determined that the compressor has failed, and the magnet clutch is stopped.

It is a schematic block diagram of the vehicle air conditioner of Embodiment 1. It is a flowchart which shows the control procedure of the vehicle air conditioner of Embodiment 1. It is a graph which shows the relationship between the change of the rotation speed of the engine with progress of time, and the change of the refrigerant | coolant pressure by a compressor. It is a graph which shows the relationship between the pressure of the refrigerant | coolant after compression, and the torque (required torque) required in order to rotate the compression rotating shaft of a compressor. It is a graph which shows the relationship between the applied voltage to a magnet clutch, and the torque (transmission torque) which generate | occur | produces at the time of the applied voltage. It is a graph which shows the relationship between the time passage after starting of a compressor, and the variation | change_quantity of the torque required in order to rotate the compression rotating shaft of a compressor. It is a graph which shows the relationship between the change of the rotation speed of an engine with progress of time, and the change of the rotation speed of a compression rotating shaft.

  Hereinafter, an embodiment of a vehicle air conditioner of the present invention will be described with reference to the drawings. In addition, this invention is not limited to these illustrations, is shown by the claim, and it is intended that all the changes within the meaning and range equivalent to a claim are included.

<Embodiment 1>
≪Overall structure≫
The vehicle air conditioner 1 according to the first embodiment shown in FIG. 1 includes a compressor 2, a condenser 5, a reservoir 6, an expansion valve 7, and an evaporator 8 provided in the refrigerant circulation path 10, and is controlled by the control unit 4. The compressor 2 of this example includes a compression mechanism that compresses the refrigerant as the compression rotation shaft 2s rotates, for example, a scroll-type compression mechanism or a vane-type compression mechanism. As the control unit 4, an EUC (electric control unit) can be used. A pressure sensor (pressure detector) 3 for detecting the pressure of the compressed refrigerant is provided in the refrigerant circuit 10 between, for example, the reservoir 6 and the expansion valve 7 so that the pressure of the refrigerant can be monitored. It has become. The pressure sensor 3 may be provided at any position as long as it is downstream of the compressor 2 and upstream of the expansion valve 7. A known configuration can be used for these members 2, 5, 6, 7, and 8.

  The compressor 2 of this example compresses the refrigerant using the rotational power of the engine 9. Specifically, when the compressor 2 is operated by interlocking the crankshaft of the engine 9 and the compressor pulley 20 with a belt (not shown) or the like, the compressor pulley 20 and the compression rotating shaft 2 s are connected by the magnet clutch 21. By doing so, the compression rotating shaft 2s of the compressor 2 is rotated by the rotational power of the engine 9, and the refrigerant is compressed.

<< Configuration of this example >>
In the vehicle air conditioner 1 of this example, in order to reduce the waste of electric power during cooling, only the electric power necessary for transmitting the torque of the compressor pulley 20 to the compression rotating shaft 2s and rotating the compression rotating shaft 2s is used. The structure which supplies this to the magnet clutch 21 is employ | adopted. Hereinafter, a configuration for reducing waste of power during cooling will be described in detail.

[Voltage adjustment mechanism]
As a configuration for reducing waste of power during cooling, the vehicle air conditioner 1 of the present example includes a voltage adjustment mechanism 2 </ b> A that can finely adjust the applied voltage applied to the magnet clutch 21. The voltage adjustment mechanism 2 </ b> A of this example uses a Pulse Width Modulation (PWM) control circuit provided in the control unit 4 and a relay 22. The PWM control is a control for changing the voltage applied to the magnet clutch 21 by turning the relay 22 on and off at high speed. The relay 22 is connected to a power supply of + B volts.

  Here, PWM control can be performed using a switching element instead of the relay 22. Since the switching element can adjust the application period of the pulse voltage on the microsecond order, the applied voltage can be adjusted with higher accuracy.

[Voltage deriving section]
The vehicle air conditioner 1 of this example includes a voltage deriving unit 40 provided in the control unit 4 as a configuration that reduces waste of power during cooling. The voltage deriving unit 40 transmits the torque of the compressor pulley 20 to the compression rotating shaft 2s based on the detection result of the refrigerant pressure by the pressure sensor 3, and applies it to the magnet clutch 21 necessary for rotating the compression rotating shaft 2s. Obtain the applied voltage. That is, in the voltage deriving unit 40, the magnet clutch 21 exhibits a coupling force that does not cause a problem that the compressor pulley 20 slips and the angular velocity of the compression rotation shaft 2 s is slower than the compressor pulley 20 or the compression rotation shaft 2 s does not rotate. Determine the applied voltage. Here, the applied voltage obtained by the voltage deriving unit 40 is equal to or less than the maximum voltage (+ B volts) that can be applied to the magnet clutch 21.

  For the derivation of the applied voltage, it is preferable to use the correlation between the pressure of the refrigerant and the applied voltage obtained in advance by a test or the like. For example, use of the correlation shown in FIGS. The correlation in FIG. 4 is a correlation between the pressure of the refrigerant compressed by the compressor 2 and the torque required to rotate the compression rotating shaft 2s at that pressure (hereinafter referred to as required torque). Moreover, the correlation of FIG. 5 is a correlation of the applied voltage to the magnet clutch 21 and the torque (transmission torque) generated at the applied voltage. When determining the applied voltage to the magnet clutch 21 using these correlations, the voltage deriving unit 40 acquires information on the pressure of the refrigerant from the pressure sensor 3, and based on the correlation shown in FIG. Find the required torque corresponding to the pressure. And the voltage derivation | leading-out part 40 calculates | requires the applied voltage to the magnet clutch 21 which can obtain the transmission torque more than required torque based on the correlation shown in FIG.

  When the applied voltage is determined by the voltage deriving unit 40 described above, the relay 22 is operated by the PWM circuit of the control unit 4 and the magnet clutch 21 is operated with the applied voltage. When a switching element is used instead of the relay 22, the applied voltage can be controlled more precisely.

[Operation determination unit]
The vehicle air conditioner 1 of this example further includes a configuration that monitors the operation state of the compressor 2 and performs an appropriate response according to the monitoring result. In this example, the operation determination part 41 provided in the control part 4 performs the monitoring. The operation determination unit 41 monitors the rotational speed of the engine 9 and the refrigerant pressure, and monitors whether the refrigerant pressure increases or decreases in conjunction with the increase or decrease of the rotational speed of the engine 9. It is determined whether or not the refrigerant pressure is obtained. Since the rotational speed of the engine 9 and the refrigerant pressure with the passage of time change substantially in parallel, if the rotational speed of the engine 9 and the refrigerant pressure deviate by more than a set value, the operation of the compressor 2 is abnormal. I can judge. That is, the operation determination unit 41 acquires information on the change in the rotation speed of the engine 9 and information on the change in the refrigerant pressure at that time, and the relationship between the rotation speed of the engine 9 and the pressure of the refrigerant exceeds the set value. When the difference is so large, it is determined that the compressor 2 is abnormal.

  The reason why the refrigerant pressure corresponding to the rotational speed of the engine 9 cannot be obtained is that, for example, the belt is slipping with respect to the magnet clutch 21 due to wear of the belt, or the magnet clutch rotates due to the belt being cut or detached. You can mention what you are not doing. In addition, there is a possibility that the compressor 2 breaks down and the compression rotating shaft 2s cannot rotate, and the magnet clutch 21 is slipping.

  The correspondence according to the determination result of the operation determination unit 41 can be broadly divided into the following two. The first response is to correct the voltage applied to the magnet clutch 21 to a higher value. As already described, since the applied voltage is determined based on a correlation obtained in advance, the correlation may be shifted due to aging of each component of the vehicle. There is a possibility that the compression rotating shaft 2s operates normally by correcting the applied voltage.

  The second response is to determine that a failure requiring repair such as a failure of the compressor 2 has occurred and stop the operation of the magnet clutch 21. For example, even if the voltage that can be applied to the magnet clutch 21 is maximized, it is possible to determine that a problem such as a failure of the compressor 2 has occurred if the refrigerant pressure corresponding to the rotational speed of the engine 9 cannot be obtained. In this case, it is preferable to notify the driver of the failure of the compressor 2 by turning on an alarm lamp or sounding a buzzer and prompt the driver to repair the vehicle.

≪Control procedure≫
Next, the control procedure of the vehicle air conditioner 1 of this example will be described based on the flowchart of FIG. 2 and the graphs of FIGS. Refer to FIG. 1 for the components with reference numerals.

  First, when the cooling of the vehicle air conditioner 1 in FIG. 1 is turned on, the control unit 4 applies the maximum voltage to the magnet clutch 21 (denoted as MC in FIG. 2) as shown in step S1 in FIG. In the vehicle air conditioner 1 of this example, the power supply voltage (+ B volts) which is the maximum voltage is applied to the magnet clutch 21 by keeping the relay 22 ON.

  In step S2, the operation determination unit 41 of the control unit 4 determines whether the torque of the compressor pulley 20 is properly transmitted to the compression rotation shaft 2s. The determination can be obtained from the correlation between the rotational speed of the engine 9 and the refrigerant pressure in FIG. 3, the horizontal axis represents time, the vertical axis on the left side represents the engine speed (rpm), the right side represents the refrigerant pressure (MPa), the solid line represents the change in the engine 9 speed, and the dotted line represents the refrigerant pressure. Shows changes. As shown in this graph, if torque transmission is appropriate, the pressure of the refrigerant fluctuates in conjunction with the change in the rotational speed of the engine 9 indicated by the solid line. However, if torque transmission is inappropriate, the refrigerant pressure deviates greatly from the broken line, as shown by the two-dot chain line.

  When the pressure of the refrigerant deviates from the broken line by a predetermined value or more, the operation determining unit 41 determines that the belt is cut, the belt is slipped with respect to the compressor pulley 20, or the magnet clutch 21 is slipping. The clutch 21 is stopped (step S3). At the same time, the control unit 4 notifies the occupant of the failure of the vehicle air conditioner 1 by turning on a warning light indicating the failure of the vehicle air conditioner 1 or sounding an alarm. On the other hand, when the deviation of the measured refrigerant pressure from the broken line is less than a predetermined value, the operation determination unit 41 determines that torque is properly transmitted when the maximum voltage is applied to the magnet clutch 21, The control unit 4 performs the next S4.

  In step S4, the voltage deriving unit 40 of the control unit 4 calculates an applied voltage required for the magnet clutch 21 from the refrigerant pressure. For calculating the applied voltage, the correlation shown in FIGS. The horizontal axis in FIG. 4 is the pressure (MPa) of the refrigerant compressed by the compressor 2, and the vertical axis is the necessary torque (N · m) required to rotate the compression rotating shaft 2s at that pressure. . The correlation between the refrigerant pressure (x) and the required torque (y) can be expressed by a linear expression (y = a × x + b). On the other hand, the horizontal axis in FIG. 5 represents the applied voltage to the magnet clutch 21 and the vertical axis represents the transmission torque (N · m) generated at the applied voltage. The correlation between the applied voltage and the transmission torque can also be expressed by a linear expression. The voltage deriving unit 40 acquires information on the pressure of the refrigerant from the pressure sensor 3, and obtains a necessary torque corresponding to the pressure of the refrigerant based on the correlation shown in FIG. And the voltage derivation | leading-out part 40 calculates | requires the applied voltage to the magnet clutch 21 which can obtain the transmission torque more than required torque based on the correlation shown in FIG.

  In step S <b> 5, the calculated applied voltage is applied to the magnet clutch 21 by PWM control of the relay 22.

  In step S6, the operation determining unit 41 determines again whether the torque of the compressor pulley 20 is properly transmitted to the compression rotating shaft 2s when the magnet clutch 21 is operated with the calculated applied voltage. If a judgment result is YES, it will return to Step S4. By looping S4 to S6, as shown in FIG. 6, the magnet clutch 21 can be operated so that the transmission torque corresponding to the required torque can be exhibited. In FIG. 6, the horizontal axis represents time, the vertical axis represents torque (N · m), the thin line represents the transmission torque, the thick line represents the required torque, and the upper dotted line represents the transmission torque corresponding to the maximum applied voltage. As shown in FIG. 6, according to the vehicle air conditioner 1 of this example, the magnet clutch 21 can be operated with a transmission torque that slightly exceeds the required torque.

  If the determination result in step S6 is No, that is, if the torque is not properly transmitted, the correlation for deriving the applied voltage is not appropriate, or a failure such as a failure of the compressor 2 has occurred. Conceivable. Therefore, the control unit 4 first corrects / overwrites the applied voltage calculation formula as shown in step S7 (step S7). For example, increasing at least one of “a” and “b” in y = a × x + b, which is the correlation between the refrigerant pressure (x) and the required torque (y), can be mentioned.

  After step S7, the process returns to step S1. If the maximum voltage is applied to the magnet clutch 21 in step S1 and it is determined in step S2 that torque is not properly transmitted, it is considered that a failure has occurred in the vehicle air conditioner 1 during traveling. The process proceeds to step S3.

  On the other hand, if the torque is properly transmitted by applying the maximum voltage to the magnet clutch 21, it is considered that the failure does not require at least repair. Therefore, step S4 is performed using the corrected calculation formula, and the correction is performed. An applied voltage based on the equation is applied to the magnet clutch 21 (step S5). If the transmission of torque is appropriate, steps S4 to S6 based on the correction formula are repeated, and if not, the calculation formula is corrected again (step S7).

≪Effect≫
According to the above configuration, as shown in FIG. 6, the applied voltage can be varied and applied to the magnet clutch 21 so that the transmission torque according to the required torque can be exhibited. That is, since an excessive voltage is not applied to the magnet clutch 21, waste of electric power associated with the use of cooling can be reduced. As a result, the energy of the engine 9 used for power generation can be reduced, and the fuel efficiency of the vehicle can be improved. Moreover, even in hybrid vehicles that have become popular in recent years, it is possible to extend the distance traveled by electric power by reducing waste of electric power. As a result, the time / opportunity for operating the engine for power generation can be reduced, and the fuel efficiency of the vehicle can be improved.

<Embodiment 2>
The correlation between the rotational speed of the engine and the rotational speed of the compression rotation shaft of the compressor can also be used to determine whether torque transmission in steps S2 and S6 in the flowchart of FIG. 2 is appropriate. In that case, the vehicle air conditioner 1 of FIG. 1 is provided with a sensor for measuring the rotational speed of the compression rotating shaft 2s.

  FIG. 7 is a graph showing the correlation, in which the horizontal axis represents time and the vertical axis represents the number of rotations (rpm). A thin line is a change in the rotational speed of the engine 9, a thick line is a change in the rotational speed of the compression rotary shaft 2s, and a dotted line is a change in the threshold value for judging that torque transmission is not appropriate. The threshold value changes according to the rotational speed of the engine 9. In this case, if the torque transmission is appropriate, the rotational speed of the compression rotating shaft 2s does not fall below the threshold value. If the torque transmission is inappropriate, the rotational speed of the compression rotating shaft 2s is a two-dot chain line. As shown, it falls below the threshold.

  According to the configuration of this example, since the rotation of the compression rotating shaft 2s is directly monitored, a failure of the vehicle air conditioner 1 can be detected quickly.

  The vehicle air conditioner according to the embodiment can be suitably used to reduce the power consumption of the vehicle.

DESCRIPTION OF SYMBOLS 1 Vehicle air conditioner 2 Compressor 2s Compression rotating shaft 2A Voltage adjustment mechanism 20 Compressor pulley 21 Magnet clutch 22 Relay 3 Pressure sensor (pressure detector)
4 Control Unit 40 Voltage Deriving Unit 41 Operation Determination Unit 5 Capacitor 6 Reservoir 7 Expansion Valve 8 Evaporator 9 Engine 10 Refrigerant Circuit

Claims (2)

A compressor having a compression mechanism for compressing the refrigerant with rotation of the compression rotation shaft;
A magnet clutch that connects a compressor pulley that rotates with the power of the engine to the compression rotation shaft as required;
A pressure detector for detecting the pressure of the refrigerant compressed by the compressor;
A vehicle air conditioner comprising: a control unit that controls the operation of the magnet clutch with a predetermined applied voltage;
The control unit includes a voltage deriving unit that obtains the applied voltage necessary to rotate the compression rotating shaft by transmitting torque of the compressor pulley to the compression rotating shaft based on a detection result of the pressure detector. A vehicle air conditioner provided. The controller is
An operation determining unit that determines whether or not the pressure of the refrigerant according to the rotational speed of the engine is obtained;
The vehicle air conditioner according to claim 1, wherein the applied voltage is corrected or the magnet clutch is stopped according to a determination result of the operation determination unit.

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