The simplest electric fan wiring diagram is good for its simplicity. But you can make several changes to it to make it more perfect. You can make the fan two-speed, and also take a large current from the sensor using a relay. And it will not hurt to carry out a smooth start of the engine.
In order to save money and simplify the design, a simplified circuit for turning on the cooling fan is used on cars. The circuit includes a fan motor, fuse, temperature sensor and connecting wires. The electric motor is connected to ground, as well as to the positive of the battery through a fuse. A temperature sensor is included in the break in the ground wire.
This circuit is good for its simplicity, no need to use expensive elements, and the number of wires is minimal. But there are also disadvantages to it. For example, a temperature sensor acting as a switch passes a large current through itself, which affects its service life. And another minus is the abrupt start of the engine. The load on the motor rises sharply to the maximum value, and this negatively affects the condition of the electric motor.
Using an electromagnetic relay
The use of a simple relay will slightly complicate the circuit, but will save the temperature sensor from the presence of a large current. A large current will flow through the relay contacts. It is cheaper and easier to replace a relay than a temperature sensor to turn on an electric fan. To carry out the upgrade, you will need a wire and a relay with a bracket for attaching to the body.
Disconnect the temperature sensor, and the wires that were on it must be connected to the normally open pair of contacts of our relay. Half of the job is done, the power section is ready. Now control. We connect one output of the temperature sensor to ground, but the second is connected to the relay coil.
From the second terminal of the coil, you need to stretch the wire to the positive terminal of the battery. It is advisable that the connection is made through a fuse, the magnitude of the operating current of which can be 1 Ampere. The coil draws a small amount of current, so the worst thing that can happen is a short circuit in the wiring. Subsequently, you can connect a forced switch-on button in parallel to the temperature sensor, which you can install in the car.
Application of semiconductors
Instead of an electromagnetic relay, you can use a thyristor switch, or a field-effect transistor design. The essence is the same, only there are no moving contacts, their functions are performed by electrons and holes in the semiconductor crystal. But do not forget about the cooling of thyristors and transistors, install radiators that will be able to provide the necessary heat transfer.
Soft engine start is a very useful function for motor control. This innovation will ensure a gradual increase in the load on the electric motor. Such an undertaking is carried out by using PWM modulation. But along with all the innovations, you can use a second temperature sensor in the cooling system, whose response temperature is 5 degrees lower than that of the main one.
If, when the main sensor is triggered, the fan turns on at full power, then when the second sensor is triggered, its speed should be half as much. To do this, you will have to use a resistor when connecting. The one that is installed on the stove fan is perfect. This will prevent the temperature in the system from reaching extreme values.
