JPH0344206B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a cooling device for a vehicle engine that includes a motor that drives an engine cooling fan such as a radiator fan.

[Description of Prior Art] As a conventional cooling device for a vehicle engine, there is one disclosed in, for example, Japanese Utility Model Application Publication No. 59-528. As shown in FIG. 2, this type of vehicle engine cooling system has a thermal switch 101 that closes contacts when it senses that the water temperature in the engine's cooling system, such as a water jacket, has exceeded a predetermined value. Once completed, the power supply 12
3 flows into the coil 117 of the thermal relay 115 via the thermal switch 101. As a result, the coil 117 is energized and the normally open contact 125 of the thermal relay 115 is closed to form a circuit, so that a current iM is applied from the power supply 123 via the normally open contact 125 to the motor that blows cooling air to the radiator. Electric power is supplied to the fan 127, and the motor fan 127 is driven.

However, in the above configuration, after the thermal switch 101 detects that the water temperature of the engine cooling system has exceeded a predetermined value and closes the
If a failure occurs, for example, when the harness coupler of the sensor comes off due to vehicle vibration or the like while the motor fan 127 blows cooling air to the radiator, the power supply from the power source 123 to the motor fan 127 is cut off. Therefore, the motor fan 127
The drive of is stopped. Therefore, if the supply of cooling air to the engine is cut off and the vehicle continues to run in that state, the engine temperature will continue to rise and eventually overheat.

[Object of the Invention] Therefore, the present invention aims to improve the above-mentioned problems.The purpose of the present invention is to prevent a malfunction after a sensor for detecting engine temperature, such as a thermal relay, detects a temperature higher than a predetermined value and closes. To provide a cooling device for a vehicle engine that does not cause the engine to overheat even when the engine is heated.

[Structure of the Invention] A feature of the present invention for achieving the above-mentioned object is that, in a cooling device for a vehicle engine having a motor that drives an engine cooling fan, the motor is connected to a power source of the motor by a first electric wire; The first signal is output when the temperature is above a preset reference value, and the second signal is output when the engine temperature is below a preset reference value.
engine temperature detection means that outputs a signal; and a second electric wire connected to a power source side of the engine temperature detection means, the motor is connected from the time the first signal is input until the reset signal is input. and a reset circuit that outputs the reset signal when the second signal is input.

In the above configuration, when the engine temperature detection means (thermal switch) detects that the temperature of water circulating in the engine cooling system has exceeded a predetermined value, the cooling means (motor fan that blows cooling air to the radiator) is activated. A driving circuit is formed.
Since the circuit is formed as a self-holding relay circuit, the cooling means continues to be driven until the engine temperature detection means detects that the water temperature value has fallen below a predetermined value. Therefore, even if the circuit is opened due to a malfunction such as poor contact in the temperature detection means, the cooling means continues to be driven while the vehicle is running.

[Description of Embodiment] FIG. 1 is a control circuit diagram of a cooling device for a vehicle engine according to an embodiment of the present invention.

In Fig. 1, a thermal switch 1 as an engine temperature detection means has a contact A that closes when the engine cooling water temperature is below a predetermined value (reference value) and a contact A that closes when the water temperature exceeds a predetermined value. Contact B which closes at
It is equipped with A coil 7 of a relay 5 is connected to the contact A via a wiring 3. A wiring 13 having a normally closed contact 9 of the relay 5 and a diode 11, which are opened when the coil 7 is excited, and a wiring 19 having the coil 7 of the relay 15 are connected to the contact B in parallel. ing. The wiring 13 and the wiring 19 are each connected to a wiring 21. The wiring 21 is connected to the wiring 3 with respect to the power supply 23.
The normally open contact 25 of the relay 15 is connected in parallel with the coil 17 and is closed when the coil 17 is excited, and the cooling that is sent from the engine's water jacket to the radiator via an outlet hose or the like. Motor fan 2 for blowing cooling air into water
7.

Here, the reference numeral 27a is a motor that is integrated with the fan of the motor fan 27 so as to drive the fan.

Further, the components of the above-described embodiments are compared with the components described in the claims as follows.

The wiring 3 is the first electric wire, the thermal switch 1 is the temperature detection means, the wiring 13 is the second electric wire, the normally closed contact 9 and the diode 11 of the relay 5 are the drive holding circuit, and the relay 5 coil 7
is the reset circuit. Further, closing of contact A of thermal switch 1 outputs a first signal, closing of contact B outputs a second signal, and normally closed contact 9 of relay 5
The opening of the signal corresponds to the output of the reset signal.

The operation of the above circuit will be explained below.

If the temperature of the cooling water circulating in the engine cooling system is below a predetermined value, the contact A side of the thermal switch 1 is closed, so that the current iA supplied from the power supply 23 flows through the contact A of the thermal switch 1. It flows into the coil 7 and excites the coil 7. The normally closed contact 9 is therefore in an open state, which remains open until the coil 7 is demagnetized. As the engine temperature rises, the temperature of the cooling water also rises, and when it exceeds a predetermined temperature value, the thermal switch 1 detects this and opens the contact A and closes the contact B.
Therefore, the current iB supplied from the power source 23 excites the coil 17 via the contact B of the thermal switch 1, so the normally open contact 25 is closed, and the motor fan 2 blows cooling air from the power source 23 to the radiator.
A current iM flows into the motor fan 27 to drive the motor fan 27. The normally closed contact 9 remains closed until the thermal switch 1 closes the A contact again and excites the coil 7. Therefore, even if contact B opens due to, for example, the harness coupler of thermal switch 1 coming off due to vehicle vibration, a portion iD of current iM is transferred to diode 11 and normally closed contact 9.
Since the flow continues to coil 17 through
7 is self-retained without being demagnetized. Therefore, the motor fan 27 continues to drive until the malfunction of the thermal switch 1 is recovered and the normally closed contact 9 is opened by closing the A contact again, or until the running of the vehicle is stopped. Cooling air is continuously blown from the radiator to the cooling water flowing into the radiator via an outlet hose or the like.

The content explained above only relates to one embodiment according to the present invention, and does not mean that the present invention is limited to the above content only. For example, an electronic circuit control such as a microcomputer may be used instead of a self-holding relay circuit. There is no problem in controlling the drive of the motor fan using means.

[Effect] As explained above, according to the present invention, even if a failure occurs after the means for detecting engine temperature detects a temperature equal to or higher than a predetermined value and drives the cooling device, the engine will not overheat. It is possible to provide a cooling device for a vehicle engine that does not require a cooling device.

[Brief explanation of drawings]

FIG. 1 is a control circuit diagram of a vehicle cooling device according to an embodiment of the present invention, and FIG. 2 is a control circuit diagram of a vehicle cooling device according to an example of the prior art. 1...Thermal switch, 5...Relay, 7...
... Coil, 9 ... Normally closed contact, 11 ... Diode, 15 ... Relay, 17 ... Coil, 25 ...
Normally open contact, 27...Motor fan.

Claims (1)

[Scope of Claims] 1. In a vehicle engine cooling device having a motor that drives an engine cooling fan, the motor is connected to a power source of the motor by a first electric wire, and when the engine temperature is equal to or higher than a preset reference value, an engine temperature detection means which outputs a first signal and outputs a second signal when the engine temperature is below a preset reference value; A drive holding circuit that maintains the drive of the motor from the time when the first signal is input until the time when the reset signal is input, and a reset circuit that outputs the reset signal when the second signal is input. A vehicle engine cooling device characterized by: