JPS6183446A - Setting structure of temperature sensor for evaporative cooling device - Google Patents

Abstract

PURPOSE:To detect an abnormal temperature up and a liquid level abnormal drop either with a single sensor, by attaching a heat transmission member with a built-in temperature measuring part after exposing its outer circumferential surface to the inside of a water jacket and making its tip end contact with a high temperature part of a cylinder head. CONSTITUTION:A bar heat transmission member 21 is installed in such a position as being situated in a relatively upper part of a water jacket 3 and less than the setting level of a refrigerant liquid level. At this time, an outer circumferential surface of this heat transmission member 21 is attached after exposing its outer circumferential surface to the inside of the water jacket 3 and making its tip end contact with an exhaust port wall 25 of a cylinder head 4. And, a temperature measuring part of a temperature sensor 1 is installed in the inside of an intermediate part of this heat transmission member 21. With this constitution, with a single temperature sensor, detection for refrigerant temperature inside the system and detection for a local temperature rise at the exhaust port wall or the like in time of an abnormal drop in the refrigerant liquid level both are performable.

Description

[Detailed Description of the Invention] Industrial Application Field This invention stores a liquid phase refrigerant up to a predetermined level in a water jacket, cools various parts of an internal combustion engine by boiling and vaporizing the refrigerant, and discharges the generated refrigerant vapor. The present invention relates to a boiling cooling system for an internal combustion engine in which condensation is condensed in a condenser and reused, and particularly to an improvement in the mounting structure of a temperature sensor.

Conventional Technology As a cooling device for automobile engines, etc., a boiling cooling device that utilizes the boiling and condensing cycle of a refrigerant (cooling water) in place of the conventional water-cooled cooling device was developed, for example, in Japanese Patent Publication No. 57-57608.
This is described in Japanese Patent Publication No. 57-62912, etc., but these methods adjust the liquid level in the water jacket using a natural circulation method using the weight of the cooling water, so it is stable. It cannot be expected to secure the liquid level position, and there is a risk of overheating due to exposure of high-temperature parts to the gas phase, resulting in poor reliability and safety.

In response, the present applicant has proposed various boiling cooling devices in which the refrigerant liquid level in the water jacket is controlled to a predetermined level using a refrigerant supply pump (for example, Japanese Patent Application No. 145470/1983). Gansho 58-228148,
Patent application No. 1983-100156, Patent application No. 1983-14037
No. 8, etc.). This consists of a sealed refrigerant circulation system mainly consisting of a water jacket, a condenser, and a refrigerant supply pump, and is equipped with a liquid level sensor corresponding to the set level of the water jacket. (For example, a mixed liquid of water and antifreeze) is stored, and various parts are cooled by boiling and vaporizing the liquid.

The generated vapor is then led to the condenser, condensed, and collected as a liquid phase refrigerant at the bottom of the condenser.Then, the refrigerant supply pump, which operates based on the detection signal of the liquid level sensor, circulates and supplies it to the water jacket again, and the refrigerant liquid level is configured to maintain the above set level.

By controlling the refrigerant liquid level in the water jacket using the refrigerant supply pump in this way, it is possible to reliably maintain the liquid level at the set level even if load conditions change. This prevents exposure of water and secures an appropriate vapor space above the water jacket, allowing stable cooling performance to be achieved.

Problems to be Solved by the Invention In the boiling cooling system as described above, for example, if the liquid level sensor fails and remains in the ON state, the refrigerant supply pump will not operate at all, and the refrigerant liquid level will gradually decrease. Eventually, the exhaust boat wall, combustion chamber wall, etc. will be exposed in the gas phase region, and localized overheating may cause fatal damage such as melting damage and thermal distortion. Therefore, it is necessary to constantly monitor the temperature of the exhaust boat wall etc. using a temperature sensor and detect abnormally high temperatures at an early stage.

On the other hand, the above-mentioned evaporative cooling equipment is generally equipped with a temperature sensor that detects the refrigerant temperature inside the water jacket in order to control the temperature within the system and detect the completion of warm-up. The temperature of the refrigerant in the water jacket detected by the refrigerant is the same whether it is in the liquid or vapor phase, so even if the refrigerant liquid level drops excessively, it will detect the abnormality. It is not possible.

That is, conventionally, a temperature sensor for detecting the refrigerant temperature within the system with high precision and a temperature sensor for detecting abnormal temperature rise of the exhaust boat wall or the like have been required separately.

Means for Solving the Problems The temperature sensor mounting structure of the boiling cooling device according to the present invention is as follows:
A rod-shaped heat transfer member is self-coated at a position relatively above the water jacket and below the set level, and the outer peripheral surface of this heat transfer member is exposed inside the water jacket, and its tip is compared with the cylinder head. The present invention is characterized in that the temperature measuring section of the temperature sensor is placed in contact with a portion subject to a high thermal load, such as an exhaust boat wall or a combustion chamber wall, and inside the intermediate portion of the heat transfer member.

Function The above heat transfer member always receives heat from the exhaust boat wall, etc. that its tip comes into contact with, but if the refrigerant liquid level in the water jacket is above the set level, the above heat transfer member will enter the liquid phase. It is located in the refrigerant and actively causes boiling on its outer circumferential surface. Therefore, the temperature measuring section can accurately detect the boiling point of the refrigerant at that time. On the other hand, when the refrigerant liquid level falls below the set level, the heat transfer member is exposed in the gas phase refrigerant and no cooling effect is provided. Temperatures that are too high or close to the exhaust boat wall temperature are detected. This makes it possible to immediately detect a local temperature rise due to an abnormal drop in the refrigerant liquid level.

Embodiment FIGS. 1 to 3 show a mounting structure for a temperature sensor 1 according to the present invention, and FIG. 4 schematically shows an example of a boiling cooling device to which this mounting structure is applied.

First, to briefly explain the entire boiling cooling system, in FIG. 4, 2 is an internal combustion engine, 3 is a water jacket formed over the cylinder head 4 and cylinder block 5 of this internal combustion engine 2, 6 is a condenser, and 7 is a A refrigerant supply pump that can be driven in both forward and reverse directions, 8 a cooling fan, 9 a reservoir tank installed outside the refrigerant circulation system, and in normal operation, the height of the first liquid level sensor 10 of the water jacket 3 is The liquid phase refrigerant occupies the other side, and the condenser 6
The liquid phase refrigerant is aged up to an appropriate height within the space, and the remaining space is a gas phase refrigerant area. The second solenoid valves 11 and 12 are "closed," and the three-way type third solenoid valve 13 is "flow path B." In this state, the steam generated within the water jacket 3 is sent to the condenser 6, where it is condensed and liquefied by the forced cooling air from the cooling fan 8 linked to the running air and the temperature sensor 1. The liquefied refrigerant is temporarily stored in the lower part of the condenser 6, and from there, the liquid level in the water jacket 3 is increased by driving (forward rotation) the refrigerant supply pump 7 based on the detection by the first liquid level sensor 1o. It is circulated and supplied to keep the level constant.

In addition, when the system temperature fluctuates relatively significantly from the target temperature, the third solenoid valve 13 is set to "flow path AJ" and the refrigerant supply pump 7 is rotated forward or reverse to force the liquid phase refrigerant to be discharged. The refrigerant is introduced into the condenser 6, and the heat radiation amount is variable controlled by lowering and raising the refrigerant liquid level within the condenser 6.

On the other hand, at the start of operation, the first magnetic valve 11 is "open" and the third magnetic valve 11 is "open".
The solenoid valve 13 becomes the "flow path A" and the refrigerant supply pump 7 is driven (reversely) for a certain period of time, liquid phase refrigerant is introduced from the reservoir tank 9 outside the system, and the air in the system is passed through the air exhaust passage 14.
from the system. And once the water is full,
11th! The solenoid valve 11 is "closed" and the second solenoid valve 12 is "open", and the excess refrigerant is discharged using the vapor pressure generated within the system.

Additionally, if the liquid phase refrigerant drops excessively for some reason during the above operation and the temperature flash detected by the % temperature sensor 1 rises abnormally, an alarm buzzer (not shown) is activated and the refrigerant supply pump 7 is activated. Abnormality avoidance operations such as forced refrigerant replenishment are performed.

A second liquid level sensor 5 is provided at the bottom of the condenser 6, which controls the lowering of the liquid level and regulates the lowest liquid level when discharging surplus refrigerant, and controls the refrigerant vapor system. Prevents leakage outside.

Next, the mounting structure of the temperature sensor 1 will be explained based on FIG. 1.2. As shown in FIG. 3, this temperature sensor 1 includes a rod-shaped heat transfer member 21 having a large-diameter mounting base 21 a at its base end, and a molded portion inside the heat transfer member 21 approximately at the center thereof. The heat transfer member 21 is fixed to the cylinder head outer wall 24 on the side of the exhaust port 23 with the heat transfer member 21 protruding into the water jacket 3. The heat transfer member 21 is
For example, the exhaust port wall 25 and the cylinder head outer wall 24 are made of metal with high heat transfer coefficient such as brass.
It is disposed diagonally across the tip 21.
b is in contact with the exhaust port wall 25. Similarly, in order to ensure a sufficient contact area, the tip portion 21 of the heat transfer member 21
b has a conical shape, and the exhaust port wall 25 is formed with a pedestal portion 25a for receiving it. Further, the outer circumferential surface of the heat transfer member 21 is exposed as it is inside the water jacket 3, and is normally submerged in the liquid phase refrigerant whose liquid level is controlled at a set level L.

Therefore, if the refrigerant liquid level is maintained at the set level L, the heat transferred from the exhaust port wall 25 to the heat transfer member 21 is lost due to boiling that occurs on the outer circumferential surface, and affects the thermistor element 22. Never. Similarly, there is no thermal influence from the cylinder head outer wall 24, and the temperature of the liquid phase refrigerant can be detected with extremely high accuracy. If the refrigerant level drops due to failure of the first liquid level sensor 10 or the like and the refrigerant is not refilled normally, the temperature will immediately rise due to the thermal influence from the exhaust port wall 25.

As mentioned above, in the boiling cooling device, the temperature is normally controlled extremely stably, so it is possible to judge that an abnormal state exists even if the temperature rises by a very small value, for example, about 5 to 10 degrees Celsius. , prompt response is possible. same,
It can also be configured to make more accurate judgments based on the gradient of temperature rise.

Further, FIG. 5 shows an embodiment in which fins 21a are provided on the outer peripheral surface of the heat transfer member 21. As shown in FIG. According to this embodiment, a more sufficient heat exchange area can be ensured by the fins 21c, and it is possible to further improve the detection accuracy in the normal state where the fins are immersed in the liquid phase refrigerant.

Similarly, although the thermistor element 22 is used in the temperature measuring section in the above embodiment, a thermocouple or the like may also be used. Further, in addition to the exhaust boat wall 25 described above, a combustion chamber wall, a sub-combustion chamber wall of a diesel engine, etc. can also be configured as a detection target.

Effects of the Invention As is clear from the above explanation, the temperature sensor mounting structure of the evaporative cooling device according to the present invention allows highly accurate detection of the refrigerant temperature in the system with a single temperature sensor and detection of refrigerant liquid level abnormalities. It becomes possible to detect a localized temperature rise on the wall of the exhaust boat when the temperature drops, and it is possible to improve the safety and reliability of the boiling cooling device without increasing the number of sensors.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a cylinder head showing the temperature sensor mounting structure according to the present invention, Fig. 2 is a sectional view taken along line n-■, Fig. 3 is a sectional view of the temperature sensor, and Fig. 4 is a boiling point. FIG. 5 is an explanatory diagram of the overall structure of the cooling device, and FIG. 5 is a sectional view showing different embodiments of the temperature sensor. 1.Temperature sensor, 3.φ water jacket, 4.
...Cylinder head, 21...Heat transfer member, 22...
Thermistor element, 25...exhaust boat wall. Outside 2 people 1 - - - Warm passing 3 - - - War 7〉 τ Kerato 4 - - Cylinder head 2l - - - f Loud sound p o No. 25-1 - Exclusion po M Fallen Figure 3 ■ Figure 5

Claims (1)

[Claims] (1) A water jacket formed in the cylinder head and cylinder block in which liquid phase refrigerant is stored up to a set level specified by a liquid level sensor, a condenser that condenses the refrigerant vapor generated here with outside air, and A boiling cooling device for an internal combustion engine, comprising a refrigerant supply pump that circulates liquid phase refrigerant condensed in the condenser to the water jacket so as to maintain the refrigerant liquid level at the set level based on the detection signal of the surface sensor. A rod-shaped heat transfer member is disposed at a position relatively above the water jacket and below the set level, and the outer circumferential surface of the heat transfer member is exposed inside the water jacket, and its tip is connected to the cylinder. 1. A temperature sensor mounting structure for a boiling cooling device, characterized in that a temperature measuring part of the temperature sensor is placed in contact with a portion of a head that has a relatively high heat load and inside an intermediate portion of the heat transfer member.