JPH0315366Y2 - - Google Patents

Description

[Detailed description of the invention] This invention provides a temperature detector that detects the temperature of the cooling water in the middle of the pipe where cooling water flows from the automobile radiator to the condensing tank. This is an engine overheat prevention device that stops the engine and prevents overload.

The power of the compressor of an air conditioner installed in a car is generally transmitted from the car's engine through a belt or the like. Therefore, the load on the engine increases due to the operation of the compressor in addition to the feeding, and the radiator 2 shown in FIG. 1 is accompanied by an increase in the temperature of the cooling water, which causes overheating of the engine. As a result, when the temperature of the cooling water rises abnormally, the compressor must be stopped to prevent overheating due to increased engine load. If appropriate measures are not taken, the cooling water pressure will rise against the pressure of the pressurizing valve 1 in the radiator cap at the top of the radiator 2, and a portion of the cooling water will be transferred to the condensing tank connected by the water pipe 4. It will be leaked within 3 days.

Conventionally, this type of engine overheating prevention method has generally been carried out by detecting the upper limit temperature allowed for the cooling water in the radiator 2. However, in this case, the temperature of the cooling water flowing into the condensing tank 3 is not constant due to outside temperature, operating conditions, variations in the pressure of the pressure valve 1 of the radiator cap, clogging of foreign objects, etc. The temperature must be set slightly lower than the permissible temperature. Therefore, in order for the compressor to continue operating, the detected temperature is set even lower, which causes the compressor to shut down at a point below the engine's capacity, which causes the air conditioner to lose its role. There are also disadvantages that cannot be achieved. Furthermore, the temperature detector requires precision, which increases the cost of parts, and furthermore, the permissible water temperature of the radiator 2 differs depending on the type of car, so it lacks versatility.

The present invention eliminates such drawbacks of the conventional technology and prevents overheating of the engine connected to the automobile air conditioner by detecting the temperature of the cooling water in the radiator as it flows into the condensing tank. To provide a highly versatile and inexpensive engine overheat prevention device using parts that do not require precision.

Embodiments of the present invention will be described below with reference to the drawings.

As shown in Fig. 1, the present invention has a radiator cap with a pressure valve 1 at the top that is opened and closed by pressure. A temperature detector 5 is provided that allows the contacts to open and close depending on the temperature. Now, the temperature of the engine cooling water is rising, and the saturated vapor pressure inside the radiator 2 is rising.
When the pressure becomes higher than the pressure specified by the pressurizing valve 1, the pressurizing valve 1 opens and the heated and pressurized cooling water flows through the water pipe 4 and flows into the condensing tank 3. At this point, a temperature detector 5 such as a bimetal connected in the middle of the water pipe 4 operates to stop the compressor of the air conditioner. In this circuit, when the ignition plug switch 6 is closed as shown in Fig. 2, the relay 7 is activated.
The relay contact 7' is closed, and the cooling fan switch 8 is operated to rotate the cooling fan motor 9.
Furthermore, the switch 10 is closed to start the engine operation. When the temperature of the cooling water rises due to engine operation, a thermostat switch 11 near the engine closes. At this time, if the cooling water in the radiator does not reach the pressure of the pressurizing valve 1, the steam of the cooling water has not reached the temperature sensor 5.
Contact 5' of temperature sensor 5 is closed and relay 12
is energized and its contact 12' is closed, so
The compressor magnetic clutch 13 is operating. Therefore, until the cooling water reaches a sufficient temperature, the compressor is operated by the operation of the magnetic clutch 13, and the air conditioner is operated.

When the engine continues to operate and the cooling water becomes superheated, its steam pressure opens the pressurizing valve 1 and causes the cooling water to flow out into the condensing tank 3 through the water pipe 4. The temperature of this superheated cooling water is detected by the temperature detector 5 and the contact 5' is opened, so the relay 12
is de-energized, opening its contact 12'. Therefore, the supply of electricity to the magnetic clutch 13 is cut off, and the drive of the compressor is stopped.

When the compressor stops, the load on the engine decreases, so the temperature of the cooling water in the radiator 2 drops, the saturated vapor pressure in the radiator 2 drops, and low-temperature cooling water returns to the radiator 2 from the condensing tank 3. At this time, the temperature detector 5 detects the compressor re-driving temperature, closes the contact 12', and the magnetic clutch 13 is operated again to drive the compressor.

As described above, by providing the temperature sensor 5 in the middle of the water pipe 4 from the pressure valve 1 of the radiator cap of the radiator 2 to the condensing tank 3, the drive of the compressor of the air conditioner is connected. This can prevent the engine from overheating. Here, the results of comparing the effects of the present invention using actual measured values are shown in Figures 3 and 4, where the horizontal axis is the time axis and the vertical axis is the temperature axis. Temperature changes are represented. Figure 3 shows a case where no temperature sensor is installed, and the temperature on the surface of the water pipe 4 to which the temperature sensor is attached rises according to the solid line curve A, and the temperature of the water inside the pipe rises with a slight delay in time. It rises like the dotted curve B.
Along with this, the temperature of the water in the radiator 2 rises as shown by the broken line C, and finally rises above the curve C.
The engine will stop at point C'. On the other hand, by providing the engine overheat prevention device of the present invention as shown in FIG. 4, the surface temperature of the water pipe 4 is reduced by the solid line D.
controlled within a nearly constant temperature deviation as shown in
Furthermore, the temperature of the water in the pipe is controlled within deviations with a time delay as shown by the dotted line E. Along with this, the temperature of the water in the radiator 2 is changed by the curve F shown by the broken line.
The temperature is almost constant. Therefore, overheating of the engine can be prevented. Moreover, the temperature of the cooling water that returns from the condensing tank 3 to the radiator 2 is sufficiently low, for example, the sensitive temperature of the temperature detector 5 can be set to 95 ± 5 degrees Celsius, and the deviation can be set as large as ± 5 degrees Celsius, so it does not require much accuracy. An inexpensive temperature detector can be selected and used.

[Brief explanation of the drawing]

Fig. 1 is a structural diagram of an embodiment of the engine overheat prevention device of the present invention, Fig. 2 is a circuit diagram of the present invention, Fig. 3 is a curve diagram of an embodiment of the cooling water temperature in a conventional method, and Fig. 4 The figure is a curve diagram of an embodiment of the temperature of cooling water according to the present invention. In the figure, 2...Radiator, 3...Condensing tank, 4...Water pipe, 5...Temperature detector.

Claims (1)

[Scope of utility model registration request] In the engine installed in the vehicle, the temperature of the superheated cooling water is detected and the compressor of the vehicle air conditioner is installed between the water pipe that connects the radiator for cooling water heat dissipation and the condensing tank for cooling the superheated cooling water. An engine overheat prevention device characterized in that a temperature detector for stopping the engine is installed in series to prevent overload of the engine.