JP3931559B2 - Air conditioner for electric vehicles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of an air conditioner for an electric vehicle.
[0002]
[Prior art]
There is already known an air conditioner for an electric vehicle that performs cooling by cyclically repeating compression and expansion of gas (refrigerant) between a condenser and an evaporator by a compressor driven by an electric motor.
[0003]
In general, in the case of an electric vehicle, there is a limit to the size of an electric motor that can be used to drive a compressor because of the weight of the vehicle and the amount of power that can be used, and the compression capability of the compressor is also limited.
[0004]
As a result, if the compressor is stopped and the cooling is stopped, and then the compressor is restarted, if there is a large difference in gas pressure between the condenser and the evaporator, a large load is applied to the motor that drives the compressor. As a result, an excessive driving current may flow through the electric motor, or a driving element such as an inverter that drives the electric motor may be damaged.
[0005]
In addition, if the compressor is restarted with a large gas pressure difference between the condenser and the evaporator, there is a high possibility that inconvenience such as running out of oil will occur in the bearing inside the compressor, and the durability of the compressor itself may be impaired. There is also.
[0006]
Therefore, in order to avoid such a problem, in a conventional electric vehicle air conditioner, after the compressor is stopped, the compressor is restarted after waiting for several minutes until the gas pressure between the condenser and the evaporator is balanced. It was.
[0007]
However, according to such a solution, since the evaporator temperature rises during the waiting time, the blowing temperature of the air conditioner also increases, and there is a problem that comfortable cooling cannot be performed during this time.
[0008]
[Problems to be solved by the invention]
As a technique for shortening the waiting time required for restarting the compressor, for example, as shown in Japanese Utility Model Laid-Open No. 7-27909, a constant condenser fan for air cooling the condenser is detected when a restart signal for the compressor is detected. It has been proposed to reduce the load on the electric motor that drives the compressor by driving only for the time and promoting the condensation of the gas (refrigerant) staying in the condenser.
[0009]
However, when such a configuration is applied, the compressor is always restarted after a predetermined time from the start request of the compressor regardless of the pressure of the gas staying in the capacitor. Even when the gas pressure in the condenser is sufficiently low, there is a case where waiting for a predetermined time is required before restarting the compressor, and cooling cannot be started quickly.
[0010]
Moreover, since the driving time of the condenser fan is always constant, if the gas pressure in the condenser when the restart signal is detected is considerably high, the gas pressure is high with insufficient gas condensation. The compressor motor may still be driven, causing problems such as excessive drive current and damage to the drive elements. On the other hand, the gas pressure in the capacitor has already dropped sufficiently at the time of restart signal detection. In such a case, there is a problem that the start of cooling is delayed as described above.
[0011]
OBJECT OF THE INVENTION
Therefore, the object of the present invention is to improve the drawbacks of the prior art described above, so that there is no concern that an excessive driving current flows in the motor driving the compressor or that the driving element driving the motor is damaged. An object of the present invention is to provide an air conditioner for an electric vehicle that can shorten the standby time required for restarting the vehicle.
[0012]
[Means for Solving the Problems]
The present invention is an air conditioner for an electric vehicle that performs cooling by cyclically repeating compression and expansion of gas between a condenser and an evaporator by a compressor driven by an electric motor. In which a condenser fan that cools the air and an electric motor that drives the condenser fan are provided, and a pressure difference detection unit that detects a pressure difference of gas generated between the condenser and the evaporator when the compressor is stopped . The pressure difference detection means is constituted by a drive current detection storage means for detecting and updating and storing a drive current of an electric motor that drives the compressor during a predetermined period during operation of the compressor, and the drive current detection storage means An electric motor that drives a condenser fan according to the detected pressure difference An operation continuation time setting means for setting an operation time, and an electric motor drive control means for operating an electric motor that drives the capacitor fan for the set operation time while watching the elapsed time after the compressor is stopped are provided. It has a configuration.
[0013]
According to such a configuration, first, the pressure difference detecting means detects the gas pressure difference generated between the condenser and the evaporator when the compressor is stopped. Next, the operation duration setting means sets the operation time of the electric motor that drives the condenser fan in accordance with the detected pressure difference. Then, the motor drive control means watches the elapsed time after the compressor stops, and operates the motor that drives the condenser fan until the elapsed time reaches the set operation time. The operating time of the motor that drives the condenser fan is determined according to the gas pressure difference generated between the condenser and the evaporator when the compressor stops, so if the gas pressure difference is large, the operating time of the motor Is set longer, and when the gas pressure difference is small, the operation time of the motor is set shorter. As a result, even when the gas pressure in the condenser is considerably high, the compressor can be restarted after sufficiently cooling and condensing the gas in the condenser. It is possible to reliably prevent an excessive driving current and damage to the driving element. Further, when the gas pressure in the condenser is low from the beginning, the standby time required until the compressor is restarted is greatly reduced, so that the cooling can be restarted quickly.
Furthermore, the condenser cooling by the condenser fan is automatically started from the previous compressor stop time without waiting for the compressor restart request. For example, the compressor is restarted after holding the compressor stopped for a while. In such a case, the compressor can be restarted immediately without waiting.
[0014]
Further , a pressure difference detecting means for detecting a pressure difference of gas generated between the condenser and the evaporator when the compressor is stopped is provided so that a drive current of an electric motor that drives the compressor is It comprises drive current detection storage means for detecting and updating and storing.
[0015]
In this case, as long as the compressor is driven, the drive current detection storage means repeatedly detects and updates and stores the drive current of the electric motor that drives the compressor every predetermined period. Therefore, the drive current detection storage means is stored in the drive current detection storage means. The last drive current, that is, the drive current immediately before the compressor is stopped becomes a value indicating the pressure difference of the gas generated between the condenser and the evaporator when the compressor is stopped. The value of the drive current of the motor that drives the compressor is substantially the same or proportional to the drive torque of the motor, that is, the force that drives the compressor, and the larger the gas pressure difference, the more the compressor is driven. Therefore, the force required for the increase also increases, so that the value of the driving current may be used as a value indicating the pressure difference of the gas generated between the capacitor and the evaporator.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, some embodiments to which the present invention is applied will be described in detail with reference to the drawings. FIG. 1 is a conceptual diagram showing the hardware configuration of an air conditioner 1 for an electric vehicle according to an embodiment to which the present invention is applied.
[0023]
As shown in FIG. 1, the electric vehicle air conditioner 1 is sent from a compressor motor 3 that drives a compressor 2, a condenser 4 that stores gas (refrigerant) compressed by the compressor 2, and the condenser 4. The cooling effect is exhibited by taking away the surrounding heat by using the receiver 5 that relays the compressed gas, the expansion valve 6 for expanding the compressed gas delivered from the receiver 5, and the volume expansion of the compressed gas. And an evaporator 7.
[0024]
A condenser fan 8 that air-cools the condenser 4 is rotated by a condenser motor 9.
[0025]
The controller 10 for driving and controlling these elements includes a CPU, a ROM, a RAM, and the like required for arithmetic processing, and is set by a temperature setting switch for air conditioning (not shown) provided on an instrument panel or the like of an automobile. Based on the deviation between the set temperature and the current value of the evaporator temperature detected by the evaporator temperature sensor 11, the compression efficiency of the gas required for the compressor 2 at that time, specifically, the compressor 2 The target rotation speed of the compressor motor 3 to be driven is obtained, the current value of the rotation speed output from the compressor motor rotation sensor 12 is read, and based on the speed deviation between the rotation speed current value and the target rotation speed. The duty ratio of the inverter 13 is adjusted and the substance supplied to the compressor motor 3 By controlling the Do drive current, the compressor motor 3, thereby achieving the target rotational speed that is needed at that time.
[0026]
That is, the compressor motor 3 has a structure in which the speed is controlled with priority, and when the internal pressure of the condenser 4 is high and a large force is required for the compressor 2 to compress gas, the condenser 4 When the internal pressure is low and the compressor 2 can easily compress the gas, a difference occurs in the value of the drive current required to achieve the same target rotational speed.
[0027]
The compressor motor current detector 14 detects the drive current applied to the compressor motor 3 and feeds back the value to the CPU of the controller 10 via the inverter 13.
[0028]
The difference in gas pressure generated between the condenser 4 and the evaporator 7 is substantially proportional to the magnitude of the drive current flowing through the compressor motor 3 that drives the compressor 2, so that the compressor motor current detector 14 By detecting the detected drive current of the compressor motor 3, the difference in gas pressure generated between the capacitor 4 and the evaporator 7 can be known.
[0029]
That is, the pressure difference detection means in the present embodiment includes the compressor motor current detector 14, the CPU of the controller 10 that detects the value of the drive current at every predetermined period, and the controller that updates and stores the value of the drive current. The driving current detection storage means is formed by 10 RAMs (register I described later).
[0030]
Hereinafter, with reference to the flowchart of FIG. 2 showing the outline of the operation duration setting monitoring process repeatedly executed by the CPU of the controller 10 at predetermined intervals, the processing operation characterized by the electric vehicle air conditioner 1 of the present embodiment is described below. Will be described. As described above, the controller 10 performs the process for obtaining the target rotational speed of the compressor motor 3 and the process related to the adjustment of the duty ratio of the inverter 13 in the same manner as heretofore. The description of the processing is omitted because it is performed in another task, and only the task of the operation duration setting monitoring process directly related to the present invention is described.
[0031]
This operation duration setting monitoring process sets the operation time of the condenser motor 9 that drives the condenser fan 8 according to the difference in gas pressure generated between the condenser 4 and the evaporator 7 when the compressor 2 is stopped. This is a process for driving the condenser motor 9 of the condenser fan 8 during this operation time after the compressor 2 is stopped.
[0032]
The CPU of the controller 10 that has started the operation continuation time setting monitoring process for each predetermined cycle first determines whether or not the cooling execution flag F has been set, that is, the compressor 2 has already stopped and the condenser fan 8 has cooled the condenser 4. Is determined (step a1), and if the cooling execution flag F is not set, it is further determined whether or not the compressor 2 is stopped (step a2).
[0033]
The cooling execution flag F is set when the compressor 2 is stopped and the substantial operation duration setting monitoring process is first executed. Therefore, the cooling execution flag F is executed before the compressor 2 stops. The flag F is never set.
[0034]
Therefore, when the determination result of step a2 is false, that is, when the compressor 2 is being driven, the CPU constituting a part of the drive current detection storage means has the inverter 13 and the compressor motor current detector. 14, the current value of the drive current of the compressor motor 3, that is, the value proportional to the difference in gas pressure generated between the capacitor 4 and the evaporator 7 is read, and this drive current value is stored in the drive current detection memory. The data is updated and stored in the register I constituting a part of the means (step a3).
[0035]
Thereafter, while the compressor 2 is being driven, the processing of step a1 to step a3 is repeatedly performed at predetermined intervals in the same manner as described above, and the register I always stores the latest value of the driving current of the compressor motor 3. It will be updated and stored.
[0036]
If it is detected in the determination process in step a2 that the driving of the compressor 2 has been stopped while such a process is repeatedly executed, the CPU has a drive current value of 0 stored in the register I. It is determined whether or not there is (step a4).
[0037]
Since the value of the drive current stored in the register I does not become 0 at the present stage immediately after the drive of the compressor 2 is stopped, the CPU then determines that the value of the drive current stored in the register I is the first. Is greater than the set value α1 (step a5), and whether the drive current value stored in the register I is between the first set value α1 and the second set value α2 (step a5). a6) Whether or not the value of the drive current stored in the register I is between the second set value α2 and the third set value α3, or is smaller than the third set value α3 Is determined (step a7). The magnitude relationship between the set values α1, α2, and α3 is α1>α2>α3> 0.
[0038]
Here, when the determination result in step a5 is true, the difference in gas pressure generated between the condenser 4 and the evaporator 7 when the compressor 2 is stopped is considerably large, that is, as it is. When the compressor 2 is restarted, it means that excessive current may flow in the compressor motor 3 and the inverter 13 and a problem may occur. Therefore, the CPU as the operation duration setting means cools the capacitor 4 The operation duration t1 of the condenser fan 8 sufficient to sufficiently condense the gas in 4 and restart the compressor 2 safely is set in the operation time storage register t (step a8).
[0039]
If the determination result at step a5 is false and the determination result at step a6 is true, the difference in gas pressure generated between the condenser 4 and the evaporator 7 when the compressor 2 is stopped is detected. This means that it is somewhat large, that is, if the compressor 2 is restarted as it is, an excessive load may be generated in the compressor motor 3 and the inverter 13. The operation duration t2 (where t2 <t1) of the condenser fan 8 sufficient to cool the compressor 4 and sufficiently condense the gas in the condenser 4 to safely restart the compressor 2 is stored in the operation time storage register t. Set (step a9).
[0040]
Similarly, when the determination results of step a5 and step a6 are false and the determination result of step a7 is true, the CPU as the operation duration setting means cools the capacitor 4 and sets the inside of the capacitor 4 The operation duration t3 (where t3 <t2) of the condenser fan 8 sufficient to sufficiently condense the gas and sufficiently restart the compressor 2 safely is set in the operation time storage register t (step a10). ).
[0041]
In this way, the CPU which has set the operation duration time t of the condenser fan 8 in the processing of step a8, step a9 or step a10, then resets the timer T and restarts it, thereby measuring the elapsed time after the compressor stops. (Step a11), and simultaneously, the driving of the condenser motor 9 is started (step a12), the cooling execution flag F is set to 1, and the condenser fan 8 starts cooling the condenser 4 Store internally (step a13).
[0042]
As a result of setting the cooling execution flag F in this way, the determination result in step a1 in the operation continuation time setting monitoring process in the next cycle becomes true. Therefore, the CPU as the electric motor drive control means determines whether or not the elapsed time T after the compressor stops has reached the set value t (step a15), and if the elapsed time T has not reached the set value t, The cycle operation duration setting monitoring process is terminated as it is.
[0043]
Until the elapsed time T after the compressor stops reaches the set value t, in the operation continuation time setting monitoring process after the next period, only the determination process of step a1 and step a15 is repeatedly executed in the same manner as described above. During this time, the driving state of the condenser motor 9 is maintained, and the condenser 4 is continuously cooled by the condenser fan 8.
[0044]
Finally, when the determination result in step a15 is true and it is confirmed that the elapsed time T after the compressor stops has reached the set value t, the CPU as the motor drive control means performs the operation of the capacitor motor 9 Is stopped (step a16), the values of the cooling execution flag F and the register I are reset to 0 (step a17, step a18), and the operation continuation time setting monitoring process for the cycle ends.
[0045]
As a result of resetting the values of the cooling execution flag F and the register I to 0, the determination result of step a1 is false and the determination result of step a2 is true in the operation continuation time setting monitoring process after the next cycle. The value of the register I is determined in the determination process of a4. Since the value of the register I has already been reset to 0 when the capacitor motor 9 is stopped (when the step a18 is executed), The determination result of a4 is necessarily true, and the processing after step a4 is automatically not executed.
[0046]
Therefore, the condenser motor 9 is driven only once after the compressor 2 is stopped.
[0047]
Thereafter, in the operation continuation time setting monitoring process for each predetermined cycle, only the discrimination processes of step a1, step a2, and step a4 are repeatedly executed in the same manner as described above, and during this time, the driving of the compressor 2 is started again. Then, the determination result of step a2 becomes false again, and the sampling of the drive current of the compressor motor 3 is started as in the case described first.
[0048]
In the operation continuation time setting monitoring process that is first executed after the compressor 2 is stopped, when the determination results from step a4 to step a7 are all false, that is, when the compressor 2 stops, the compressor motor 3 If it is determined that the value of the drive current acting on the compressor is sufficiently small, there will be no problem with the compressor motor 3 and the inverter 13 even if the compressor 2 is restarted. The CPU as the means resets the value 0 to the register I that stores the value of the drive current when the compressor is stopped (step a14), and ends the operation duration setting monitoring process of the processing cycle.
[0049]
In this case, since the setting process of the cooling execution flag F is not performed, the situation is exactly the same as the case where the driving process of the condenser motor 9 after the compressor is stopped, and hereinafter, the operation duration setting for each predetermined cycle is performed. In the monitoring process, only the determination process of step a1, step a2, and step a4 is repeatedly executed in the same manner as described above, and the determination result of step a2 becomes false when the driving of the compressor 2 is started again. In the same manner as above, sampling of the drive current of the compressor motor 3 is started.
[0050]
As described above, depending on the magnitude of the gas pressure difference generated between the condenser 4 and the evaporator 7 when the compressor 2 is stopped, that is, depending on the magnitude of the drive current of the compressor motor 3 when the compressor is stopped. Since the length of the operation time t of the condenser motor 9 that drives the condenser fan 8 is determined, the gas in the condenser 4 is sufficiently cooled and condensed even when the gas pressure difference is considerably large. Thus, the compressor 2 can be restarted, and it is possible to reliably prevent an excessive drive current of the compressor motor 3 that drives the compressor 2 and damage to the inverter 13.
[0051]
Further, when the gas pressure in the condenser 4 is low, the value of the standby time t (set value) required until the compressor 2 is restarted is shortened, so that the cooling can be restarted quickly.
[0052]
Furthermore, the cooling of the condenser 4 by the condenser fan 8 is automatically started from the previous stop time of the compressor 2 before the restart request without waiting for the restart request of the compressor 2. In the case where the compressor 2 is restarted after maintaining the stopped state, the compressor 2 can be restarted immediately without waiting.
[0078]
【The invention's effect】
An air conditioner for an electric vehicle according to the present invention includes a pressure difference detecting means for detecting a pressure difference of gas generated between a condenser and an evaporator when the compressor is stopped, and a pressure difference detected by the pressure difference detecting means. The operation duration setting means for setting the operating time of the motor of the condenser fan that cools the condenser according to the size of the condenser, and the condenser fan for the operating time set by the operation duration setting means, watching the elapsed time after the compressor stops An electric motor drive control means for operating the electric motor to be driven, and the operation time of the electric motor driving the condenser fan is determined according to the gas pressure difference generated between the condenser and the evaporator when the compressor stops. Therefore, even if the gas pressure in the capacitor is considerably high, the gas in the capacitor Consists condensed sufficiently cooled to be able to restart the compressor, it is possible to reliably prevent damage to the excess or the driving element of the driving current of the motor for driving the compressor.
Further, when the gas pressure in the condenser is low, the standby time required until the compressor is restarted is greatly shortened, so that the cooling can be restarted quickly.
Furthermore, the condenser cooling by the condenser fan is automatically started from the previous compressor stop time without waiting for the compressor restart request. For example, the compressor is restarted after holding the compressor stopped for a while. In such a case, it is completely different from the prior art (No. 7-27909, etc.) in which cooling of the condenser is started after detection of the restart request of the compressor, and the compressor can be restarted immediately without waiting. It becomes possible.
[0079]
As a pressure difference detecting means for detecting the pressure difference of the gas generated between the condenser and the evaporator when the compressor is stopped, the drive current of the electric motor that drives the compressor is detected and stored at predetermined intervals. Since the drive current detection storage means is used, it is possible to accurately detect the pressure difference of the gas when the compressor is stopped without providing a special pressure sensor, etc., and the manufacturing cost of the air conditioner for electric vehicles Can be reduced.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a block diagram of a hardware configuration of an air conditioner for an electric vehicle according to an embodiment to which the present invention is applied.
FIG. 2 is a flowchart showing an outline of an operation duration setting monitoring process that is repeatedly executed by the controller of the embodiment every predetermined period.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electric vehicle air conditioner 2 Compressor 3 Compressor motor 4 Condenser 5 Receiver 6 Expansion valve 7 Evaporator 8 Capacitor fan 9 Capacitor motor 10 Controller (operation duration setting means, motor drive control means)
11 Evaporator temperature sensor 12 Compressor motor rotation sensor 13 Inverter 14 Compressor motor current detector (pressure difference detection means, drive current detection storage means)

Claims (1)

An electric automotive air conditioner which performs cooling by repeating compression and expansion of the gas cyclically between the condenser and the receiver and the evaporator by a compressor driven by an electric motor, the condenser fan and condenser fan for cooling the condenser And a pressure difference detecting means for detecting a pressure difference of gas generated between the condenser and the evaporator when the compressor is stopped. The drive current detection storage means detects and updates the drive current of the electric motor that drives the compressor during a predetermined period while the compressor is operating, and the pressure difference detected by the drive current detection storage means Depending on the size of the motor that drives the condenser fan And an electric motor drive control means for operating the electric motor that drives the condenser fan for the set operating time, while monitoring the elapsed time after the stop of the compressor. Air conditioner for electric vehicles.

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