JPS6316562Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a blower control device for an automobile air conditioner.

In the case of automotive air conditioners, especially auto air conditioners, the indoor blower is controlled linearly or in three stages of high speed, medium speed, and low speed using power transistors depending on the deviation from the actual indoor temperature. It is something that However, in such a device, when the terminal voltage of the indoor blower is low, the loss of the power transistor increases, so a large heat sink is required. Since the low-speed rotation of such a blower occupies most of the air conditioning time, the heat sink must be large in order to improve reliability.

Therefore, the object of this invention is to provide a blower control device that reduces the loss of the power transistor and reduces the size of the heat sink.
The gist of this is a power transistor that drives the blower according to an airflow signal, a means for connecting a capacitor fan in parallel with the power transistor when the air conditioning switch is turned off, and a means for connecting the capacitor fan to the power supply voltage when the air conditioning switch is turned on. means for directly connecting the capacitor fan to the power supply voltage; and means for prohibiting the operation of the means for directly connecting the capacitor fan to the power supply voltage when the air conditioning switch is on and the blower air flow rate falls below a predetermined value.
This blower control device for an automobile air conditioner is provided with means for connecting a capacitor fan in parallel with the power transistor when an air conditioning switch is turned on and a blower airflow amount signal falls below a predetermined value.

Therefore, in most automotive air conditioners, the blower air volume is usually low, and when the blower air volume is less than a predetermined value, the capacitor fan is connected in parallel with the power transistor, and the power transistor is turned off. Accordingly, the loss of the power transistor can be reduced, the heat sink can be made smaller, and the above-mentioned object can be achieved.

Examples of this invention will be described below with reference to the drawings.

Fig. 1 shows an embodiment of this invention, in which B is an indoor blower, PT is a power transistor,
F is capacitor blower, E is battery, IGSW
is the ignition switch, BSW is the blower off switch, ACSW is the normally open switch, SW ₁ , SW ₂
and an air conditioning switch consisting of a normally closed switch SW ₃ ,
OA ₁ and OA ₂ are operational amplifiers, T ₁ and T ₂ are transistors, and RY is a normally closed contact RY-b and a normally open contact RY-a.
relay with ZD is a Zener diode, R ₁ ~
R ₁₈ is a resistor, C ₁ and C ₂ are capacitors, V ₅ is a stabilized power supply, and IN is set in three stages depending on the deviation between the actual indoor temperature and the set temperature, for example, H (high speed), M (medium speed), L
This terminal inputs the blower air volume signal (low speed, low speed) to this input terminal IN.
When the signal is applied from a low speed), it is compared and amplified by the operational amplifier OA ₁ , and is input to the power transistor PT via the transistor T ₁ .
The rotation speed of blower B is controlled by PT. In addition,
In this embodiment, the power transistor PT is turned off during low speed signals. The capacitor fan F is rotated by applying power supply voltage when the air conditioning switch ACSW is closed, but the operational amplifier
In the comparison circuit consisting of OA ₂ , when the airflow rate signal is low, transistor T ₂ is turned on and power transistor PT is turned on.
The blower B is connected in parallel with the blower B so that current flows through the blower B.

In the above configuration, if the air conditioning switch ACSW is off (but the ignition switch
IGSW is on, blower off switch BSW is on)
In the winter, when it is cold and warm air is blown from the foot outlet, switch SW ₃ is closed, so the capacitor fan F is connected to the power transistor.
Connected in parallel with PT.

The power transistor PT receives an air blowing amount signal from the input terminal IN via the operational amplifier OA ₁ and the transistor T ₁ to drive the blower B. For example, in this embodiment, the blower B is controlled at three speeds. That is, at high speed and medium speed signals, control is performed by the power transistor PT, and at low speed, the power transistor PT is turned OFF, current flows through the capacitor fan F, and the terminal voltage of the blower B is controlled by the capacitor fan F. is determined to be low, and the blower B is rotated at a low speed. Note that, at this time, the capacitor fan F begins to rotate at a low speed for the first time.

In Figure 2, when the air conditioning switch ACSW is turned on, if the indoor temperature is far away from the set temperature and the airflow rate signal is high or medium speed,
Blower B is controlled at high or medium speed by the power transistor PT, and when the output of the operational amplifier OA ₂ is at a low level, the transistor T ₂ is turned off, and the relay RY is turned off.
When the capacitor fan F is off, it is disconnected from the power transistor PT and rotated by applying the power supply voltage. Also, when the indoor temperature approaches the set temperature and the difference decreases, and the air volume of blower B falls below the predetermined value, that is, when the input terminal
When the input air flow rate signal applied to IN becomes low speed, the output of operational amplifier OA ₂ becomes high level, transistor T ₂ is turned on, relay RY is turned on, and capacitor fan F is turned on as shown in Fig. 3. is now connected in parallel with the power transistor PT,
Current is caused to flow through the capacitor fan F via the blower B, the terminal voltage of the blower B is determined to be low, and the blower B is rotated at a low speed. Note that at this time, the rotation of the capacitor fan F becomes lower due to the voltage drop caused by the blower B, but since the indoor temperature is approaching the set temperature, the heat load is decreasing, so this does not pose a problem.

In this embodiment, the air blowing amount signal has been explained based on an example of a three-stage signal, but it is clear that the present invention is not limited to this and can also be applied to a four-stage signal or a linear control signal.

As described above, according to this invention, in an automotive air conditioner, when the air conditioning switch is off, the capacitor fan is connected in parallel with the power transistor for driving the blower, and when the air conditioning switch is on, the blower air volume is below a predetermined value. Since the capacitor fan is similarly connected in parallel with the power transistor when the power transistor is used, the loss of the power transistor can be reduced and the heat sink can be made smaller.

Furthermore, since the loss of the power transistor is borne by the capacitor fan, it has effects such as power saving.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of this invention, and FIGS. 2 and 3 are circuit diagrams showing various operational aspects of the embodiment. B...Blower, F...Condenser fan,
PT...Power transistor, ACSW...Air conditioning switch.

Claims (1)

[Scope of utility model registration request] A power transistor for driving the blower in accordance with an airflow rate signal, means for connecting a capacitor fan in parallel with the power transistor when the air conditioning switch is off, and means for directly connecting the capacitor fan to the power supply voltage when the air conditioning switch is on. and means for prohibiting the operation of the means for directly connecting the capacitor fan to the power supply voltage when the air conditioning switch is on and the blower airflow rate falls below a predetermined value; and when the air conditioning switch is on and the blower airflow rate signal is 1. A blower control device for an automobile air conditioner, comprising: means for connecting a capacitor fan in parallel with the power transistor when the value falls below a predetermined value.