JPH04339012A - Fan control device of air conditioner for vehicle - Google Patents

Abstract

PURPOSE:To prevent incorrect air blowing due to wrong detection of lock in an air conditioner for vehicle. CONSTITUTION:In a microcomputer 4, an applied voltage Vm and a motor current value Im to a blower motor 1 for driving a blower fan are detected and the lock of the blower motor 1 is detected according to a reference current value based on the applied voltage Vm. The microcomputer 4 is provided with an atmospheric temperature sensor 25 for detecting atmospheric temperature, a vehicle speed sensor 26 for detecting the travelling speed of the vehicle, a blowing mode setting device 23 for transmitting information signals on the ventilating resistance of a blower duct, and an inside/outside air selector switch 24 for environmental conditions by the air conditioner of the vehicle. The reference current value is corrected according to the detected environmental conditions.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fan control device for a vehicle air conditioner.

0002

[Prior Art] In vehicle air conditioners, if the blower motor for blowing air is locked and energized, it will cause burnout of the motor or destruction of the energizing element, so the voltage applied to the motor and the energizing If the detected current value is abnormally large with respect to the voltage applied to the motor, it is determined that the motor is in a locked state, and if the motor is locked, power to the motor is stopped.

0003

[Problems to be Solved by the Invention] However, since vehicle air conditioners are installed in vehicles that are used under various environmental conditions, the motor current value that drives the blower fan varies depending on the environmental conditions. For example, when the ambient temperature drops, the motor current value increases, and when outside air is introduced while the vehicle is running at high speed, the outside air is forced into the ventilation duct and the fan load changes. Similarly, the motor current value increases, and since the air outlets installed at various locations in the vehicle are connected by air ducts, when the air outlet is switched, the ventilation resistance changes accordingly. The load on the blower fan changes, and this change causes the motor current value to fluctuate. For this reason,
If locking is determined based on a fixed reference current value, if the motor current value fluctuates due to changes in environmental conditions as described above, there is a possibility that locking will be incorrectly determined even though the motor is not locked. As a result, abnormal operation of the air conditioner such as stopping of air blowing may occur, and comfortable air conditioning operation may not be ensured.

An object of the present invention is to provide a fan control device for a vehicle air conditioner in which when detecting a lock of a blower motor in a vehicle air conditioner, the blowing operation is less likely to be hindered due to erroneous lock detection. With the goal.

[0005]

[Means for Solving the Problems] The present invention detects the voltage and current value applied to a motor that drives a blower fan of a vehicle air conditioner, and detects the current value based on the reference current value corresponding to the applied voltage. In the fan control device for a vehicle air conditioner, the lock determination means includes an environmental condition detection means for detecting an environmental condition of the vehicle air conditioner; The technical means includes a reference value correction means for correcting the reference current value based on the environmental condition detected by the environmental condition detection means.

[0006]

According to the present invention, in order to detect locking of the blower fan motor, the applied voltage and the current value are detected, and the reference current value for lock determination is once determined based on the applied voltage. Furthermore, it detects the environmental conditions of the vehicle air conditioner, such as detecting the air temperature inside the ventilation duct and inside the vehicle, detecting the vehicle running speed, and detecting the distinction between outside air or inside air and the air outlet. The reference current value is corrected based on the fluctuation tendency of the motor current value according to the conditions determined. As a result, for example, the reference current value can be increased in consideration of the fact that the motor current value increases at low temperatures or when outside air is introduced during high-speed driving, or the reference current value can be increased depending on the ventilation resistance of the ventilation duct to the air outlet of each vehicle. and change the reference current value. As a result, if the motor current value tends to increase, by increasing the reference current value for lock determination, incorrect lock detection can be avoided and the motor will not be stopped. This ensures stable air blowing operation unless the motor actually locks up.

[0007]

[Effects of the Invention] In the present invention, since the reference current value is corrected based on the environmental conditions that cause the motor current value to fluctuate, erroneous locking is less likely to be detected and the air blowing operation is stopped. Less is.

[0008]

[Embodiment] Next, the present invention will be explained based on an embodiment of an air conditioner for a vehicle. The vehicle air conditioner of this embodiment, the circuit diagram of which is shown in FIG.
A blower fan, an evaporator, a heater core, etc. are arranged to automatically select and operate heating, cooling, and air blowing amount according to the set temperature, etc., and the present invention provides a direct current motor for driving the blower fan. (hereinafter referred to as a blower motor).

In FIG. 1, 2 is an ignition switch, 3 is a blower relay for controlling power supply to the blower motor 1, 4 is a microcomputer (hereinafter referred to as microcomputer) for controlling air conditioning, and 5 and 6 are for energizing the blower motor 1. 7 is the power transistor 5,
When the blower motor 1 is energized by 6, the current is partially bypassed and energized, and when the blower motor 1 is started, the bypass resistor is used alone to energize the blower motor 1. Lo (low) is the weakest for the blower fan. has a resistance value such that a fan speed corresponding to . 8 is a Hi relay that bypasses the power transistors 5, 6 and resistor 7 and directly applies the voltage of the battery 9 in order to drive the blower motor 1 at a fan speed corresponding to the strongest Hi (High); 10 is a This is a galvanometric resistor that detects a voltage Vr corresponding to a motor current value Im flowing through the blower motor 1.

On the other hand, the operation panel 20 for giving operation instructions to the microcomputer 4 includes an air volume setting device 21, a room temperature setting device 22, a blowing mode setting device 23, an inside/outside air changeover switch 24, and an air conditioner switch. An operating device is provided, as well as a blower motor lock indicator 30 and the like for displaying when locking of the blower motor 1 is detected. In addition, the microcomputer 4 detects the ambient temperature of the blower motor 1 in order to perform correction according to the environmental conditions of the blower motor 1 when determining a reference current value for detecting locking of the blower motor 1 as described later. The microcomputer 4 includes a sensor 25 and a vehicle speed sensor 26 for detecting the running speed of the vehicle, and further includes other sensors 27 such as an inside air sensor, an outside air sensor, and an outlet temperature sensor for air conditioning control. The actuator 40 includes a compressor, a water valve, and a temperature control damper that are driven according to the target temperature, a suction port switching damper, an outlet switching damper that is driven according to the selection of the air blowing state, and the like.

Although the ambient temperature sensor 25 is installed near the blower motor 1, an internal air sensor or other temperature sensor may also be used. The vehicle speed sensor 26 is used not only to determine whether the blower motor 1 in the vehicle air conditioner is locked, but also to control the vehicle engine. Note that 4a is an A/D converter that digitally converts each operation signal from the operation panel 20 and the detection signal from each sensor, as well as the voltage Vm applied between the terminals of the blower motor 1 and the voltage Vr detected by the galvanometer resistor 10. Convert to signal. 4b is a D/A converter.

Next, a description will be given of how the microcomputer 4 determines whether or not the blower motor 1 is locked in the vehicle air conditioner constructed as described above. The motor current value Im indicates a steady current value when the blower motor 1 is not locked, but when it is locked, it shows a significantly larger value compared to the steady current value, so the lock determination is as follows: This is done by detecting a motor current value Im and determining whether it is larger than a reference current value for lock determination. Since the motor current value Im varies depending on the voltage applied to the blower motor 1 regardless of whether the blower motor 1 is locked or not, the reference current value is determined by the voltage applied to the blower motor 1 by a predetermined calculation formula. is provided as a reference current value group consisting of a plurality of reference current values determined according to.

The determination of the reference current value group will be explained below with reference to FIG.
This will be explained with reference to. Conventionally, the reference current value group for determining whether or not the blower motor 1 is locked has been determined based on the steady current value for the voltage Vm applied to the blower motor 1 and the current value when the lock occurs, so that there is no problem during normal operation. A reference current value group is initially set by making a substantially intermediate value of the current values correspond to each applied voltage Vm (step 1).
1). However, since the motor current value Im varies depending on the environmental conditions of the blower motor 1, the environmental conditions of the blower motor 1 are detected and the initially set reference current value group is corrected according to those environmental conditions. , to avoid false lock detection.

The environmental conditions to be detected include those that cause fluctuations in the motor current value Im, such as the ambient temperature of the blower motor 1, and when introducing outside air into a vehicle air conditioner, the speed of the vehicle. The load on the blower fan changes as outside air is forced into the blower duct, depending on whether the air is being recirculated or outside air is being introduced, and if outside air is being brought in, the speed of the vehicle is being driven, and the blower duct is There is a distinction between air outlets because the airflow resistance is different depending on the airflow resistance. As mentioned above, the ambient temperature sensor 25 and the vehicle speed sensor 26 are provided as sensors for detecting these environmental conditions, but no particular sensor is provided for each detection related to the ventilation resistance of the ventilation duct. A switching signal from an inside/outside air selector switch 24 provided on the operation panel 20 and an air outlet selection signal from an air outlet mode setting device 23 are used to detect environmental conditions.

The microcomputer 4 adjusts the initially set reference current value group to the blower motor 1 according to these environmental conditions.
Temperature correction based on the ambient temperature (step 12), if outside air is introduced (step 13)
ES), vehicle speed correction (step 14), and air outlet correction according to the selected air outlet (step 15).
), to prevent false lock detection.

In temperature correction, the lower the ambient temperature, the larger the reference current value, and the higher the ambient temperature, the smaller the reference current value. In vehicle speed correction when outside air is introduced, the faster the vehicle speed, the larger the reference current value is corrected. In the air outlet correction, the ventilation resistance differs depending on the individual air outlets, and the load on the blower fan varies accordingly, so although it cannot be described as a general tendency, an example thereof is shown in step 15.

As a result of each of the above corrections, for example, as shown in FIG. 3, if the reference current value group is corrected to be large, locking may be erroneously detected even if the motor current value Im is large. There aren't many.

Furthermore, the voltage Vm applied to the blower motor 1
is low, the detected motor current value Im may become larger than the reference current value of the reference current value group corrected according to the above environmental conditions due to variations in the blower motor 1 etc. or other causes. Therefore, even if a lock is detected once, the applied voltage Vm is increased and a re-judgment is made, and the fan operation is stopped only when a lock is detected twice. This prevents the air blowing operation from stopping due to the detection of a lock.

Next, the operation of the vehicle air conditioner will be explained with reference to FIG. 4, focusing on the control operation related to lock determination in the microcomputer 4. ignition switch 2
When turned on, power is supplied to the microcomputer 4 and the microcomputer 4 starts up. When the air volume setting device 21 is set to OFF (NO in step 1), the air conditioning operation according to the operation panel 20 is not performed, and the air conditioner waits until it is turned on. When the air volume setting device 21 is turned on by adjusting the air volume desired by the driver or automatically (AUTO) (YES in step 1), predetermined activation control is performed. In the startup control, for example, when the blower relay 3 is turned on while the power transistors 5 and 6 are turned off, and a voltage V1 (for example, 4V) is applied via the bypass resistor 7, the blower motor 1 is deenergized. At this time, the 2 second timer starts counting.

As the blower motor 1 is energized, the voltage V1 is detected as the voltage Vm applied to the blower motor 1, and the reference current value I1 for determining the lock is determined based on the voltage V1 in steps 11 to 15 described above. (Step 2). On the other hand, motor current value Im is detected based on voltage Vr, and motor current value Im is compared with reference current value I1 to determine whether the motor is locked.

[0021] If the motor current value Im is smaller than the reference current value I1 (NO in step 3), it is determined that the blower motor 1 is operating normally, and the start control is performed after waiting for the completion of the two-second timer. Then, the air conditioning operation is started in accordance with the operation of the operation panel 20, and the voltage Vm applied to the blower motor 1 is changed in accordance with the control operation of the air conditioner, so that the amount of air blown corresponding to the control operation is obtained. Motor current value Im
is larger than the reference current value I1 (YES in step 3), it is repeatedly determined whether or not this continues for 2 seconds (NO in step 4), and the motor current value Im becomes smaller than the reference current value I1 within 2 seconds. If it becomes smaller, the air conditioning operation is started in the same way as in the above case.

If the state in which the motor current value Im is greater than the reference current value I1 continues for 2 seconds (YES in step 4), there is a possibility that the blower motor 1 is locked, but the blower motor 1 is actually locked. Did the motor current value Im exceed the reference current value I1 due to the lock?
Motor current value Im changes to reference current value I due to some external factor.
Whether it exceeded 1 by chance is not determined at this point.

Therefore, the voltage V applied to the blower motor 1
Temporarily change m to voltage V2 (for example, 12V) corresponding to fan speed Hi using Hi relay 8 (step 5)
. When the applied voltage Vm of the blower motor 1 is changed, in the calculation of the reference current value, a reference current value I2 corresponding to the new voltage V2 is calculated.

The locking of the blower motor 1 is re-determined by comparing the motor current value Im with the reference current value I2 corresponding to the voltage V2, and if the motor current value Im is greater than or equal to the reference current value I2 (YES in step 6). ), and repeatedly determines whether this continues for 2 seconds (NO in step 7).
, if the state in which the motor current value Im is larger than the reference current value I2 continues for 2 seconds (YE in step 7).
S) If it is determined that the blower motor 1 is locked and the blower motor 1 is energized for any longer, the blower motor 1 may be burnt out or the power transistors 5 and 6, which serve as energizing elements to energize the blower motor 1, may be damaged, etc. Therefore, the power supply to the blower motor 1 is stopped (step 8), and the motor lock indicator 3 on the operation panel 20 indicates that the lock of the blower motor 1 has been detected.
Displayed by 0.

If the motor current value Im is smaller than the reference current value I2, or if the motor current value Im becomes smaller than the reference current value I2 within 2 seconds (NO in step 6), the applied voltage Vm is compared. The lock was incorrectly detected in the lock determination based on the reference current value I1 because the voltage V1 was low, and the current applied to the blower motor 1 increased due to changing the applied voltage Vm to the voltage V2, resulting in an increase in torque. It is possible that the blower motor 1 started rotating easily due to the increase in voltage V2, or that the ice that had entered the snow melted due to the heat generated by the application of voltage V2 and the lock was released. In this case, the blower motor 1 can be considered not to be locked. Therefore, in such a case, the voltage Vm applied to the blower motor 1 is returned to the original voltage V1 (step 9), the air conditioning operation is started according to the operation on the operation panel 20, and the air conditioner is then controlled. The blower motor 1 is controlled accordingly. Therefore, a blowing operation corresponding to the control operation of the air conditioner can be reliably obtained, and stable operation can be ensured.

In the above embodiment, in the startup control of the blower motor 1, electricity is supplied using a constant voltage only by the bypass resistor 7. It may be something you do. Also, for rejudgment, the applied voltage V of the blower motor 1
m was changed from the voltage at fan speed Lo to the voltage at Hi, but the voltage is constant (
For example, the voltage may be changed to 2 V).

FIG. 5 shows a second embodiment of the present invention. In the first embodiment, the voltage Vm applied to the blower motor 1 is changed according to the control state of the blower fan, but in the second embodiment, the voltage Vm applied to the blower motor 1 is kept constant to generate the duty. Power MOSFE through part 4c
PWM control is performed to change the duty ratio of T5A. In this case, by detecting the voltage Vm applied to the blower motor 1 and the motor current value Im as an average voltage and an average current through integral processing, lock determination can be performed in the same manner as in the first embodiment. In each of the above embodiments, a vehicle air conditioner that performs cooling and heating is shown, but an air conditioner that performs cooling or heating alone may be used, or a blower controller that only controls air blowing may be used.

In each of the above embodiments, the reference current value group is calculated based on the applied voltage, but the reference current value group corresponding to each applied voltage and environmental condition is provided in the memory of the microcomputer. The reference current value corresponding to the operating state may be read out from the reference current value group according to the applied voltage Vm and the detected environmental condition. In each of the above embodiments, the correction is performed based on all of the environmental conditions such as the ambient temperature, vehicle speed, and air outlet, but it is also possible to perform the correction based only on one or more of the environmental conditions. good.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a first embodiment of a vehicle air conditioner according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation for determining a group of reference current values for lock determination in a first embodiment of a vehicle air conditioner showing an embodiment of the present invention.

FIG. 3 is a characteristic diagram showing an example of a determination result of a reference current value group for lock determination in a first embodiment of a vehicle air conditioner according to an embodiment of the present invention.

FIG. 4 is a flowchart for explaining the operation related to the lock determination of the first embodiment of the vehicle air conditioner showing the embodiment of the present invention.

FIG. 5 is a circuit diagram showing a second embodiment of a vehicle air conditioner according to an embodiment of the present invention.

[Explanation of symbols]

1 Blower motor (motor) 4 Microcomputer (vehicle air conditioner fan control device, lock determination means, reference value correction means) 23
Blowout mode setter (environmental condition detection means) 24 Inside/outside air changeover switch (environmental condition detection means) 25 Ambient temperature sensor (environmental condition detection means) 26 Vehicle speed sensor (
Environmental condition detection means) Vm Applied voltage Im Motor current value (current value)

Claims (1)

[Claims] [Claim 1] Detecting the voltage and current value applied to a motor that drives a blower fan of a vehicle air conditioner,
In a fan control device for a vehicle air conditioner, the lock determination device includes lock determination means for determining whether or not the motor is locked based on a reference current value corresponding to the applied voltage. An air conditioner for a vehicle, comprising an environmental condition detecting means for detecting an environmental condition, and a reference value correcting means for correcting the reference current value based on the environmental condition detected by the environmental condition detecting means. fan control device.