JPS60132009A - Exhaust valve temperature controlling method of internal combustion engine - Google Patents

Abstract

PURPOSE:To maintain an exhaust valve at a predetermined temperature and avoid low temperature corrosion by adjusting the heat-exchanging area of a heat exchanger which cools down an evaporated gas from a heat siphon according to an engine load, in a device which cools down the exhaust valve by the heat siphon. CONSTITUTION:A cooling material chamber 5 filled with a primary cooling material is formed in the umbrella portion 1 of an exhaust valve. And the primary cooling material which cools down the umbrella portion 1 and is evaporated condenses in the condensed pipe 15 of a heat exchanger 3, and after that, it returns to the cooling material chamber 5. A secondary cooling material is supplied to the outer circumference of the condensed pipe 15, and a secondary cooling material layer 16 and a pressed air layer 17 are formed. Thus, pressure of the air layer 17 is controlled by a pressure regulating valve 26 according to an engine load, and supply volume of the cooling material is controlled by adjusting a flow rate controlling valve 23 and a throttle valve 24. Thereby, level of the secondary cooling material layer 16 is adjusted, heat exchanging area is controlled, and low-temperature corrosion of the exhaust valve due to excessive cooling can be prevented.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an exhaust valve device for an internal combustion engine, and in particular to an exhaust valve device for an internal combustion engine that cools a valve head portion exposed to high temperatures regardless of changes in heat load and optimally controls its humidity. It's about what you're trying to get.

[Technical Background of the Invention and Problems Therewith] There are two methods of cooling exhaust valves for internal combustion engines: one that applies the principle of a closed thermosiphon, and the other that uses water to forcefully cool the exhaust valve.

In the former case, the problem was how to extract the heat from the steam to the outside. Conventionally, heat was dissipated by intermittent contact movement between the cylindrical wall of the valve stem chamber and the valve stem, but this method could not be put to practical use because the heat dissipation could not keep up with the increase in heat load and caused sticking.

In the latter case, it is not possible to maintain the desired high temperature and the product is constantly overcooled, resulting in low-temperature corrosion or damage due to increased local thermal stress, reducing its reliability and service life. was low.

Incidentally, damage to exhaust valves is relatively often caused not only by a high degree of heat generation, but also by the so-called jamming phenomenon, in which foreign matter adheres to the valve seat surface. It is known that this foreign matter adhesion is particularly significant at temperatures above a certain level. Therefore, it is important to maintain the temperature below this temperature, and to do so, two requirements must be met: cooling and monitoring the temperature.However, none of the above methods can satisfy these two requirements. This was a problem because I was unable to do so.

[Purpose of the Invention] This invention was made in view of the above-mentioned problems.The purpose of this invention is to cool the exhaust valve and monitor its temperature while applying the principle of heat syphon, thereby reducing the thermal load fluctuations of the internal combustion engine. An object of the present invention is to obtain an exhaust valve adjustment control method for an internal combustion engine that can control the exhaust valve to an optimum temperature and safely operate the internal combustion engine.

[Summary of the Invention] In order to achieve the above object, the present invention provides an exhaust valve for an internal combustion engine having a closed heat exchanger pipe, in which a primary coolant is stored inside the exhaust valve, and the vaporized secondary coolant is drawn out from the inside of the exhaust valve. The secondary coolant is condensed through indirect heat exchange, and when the condensed coolant is returned to the exhaust valve, the heat load fluctuation of the internal combustion engine is detected, and the secondary coolant is vaporized according to the detected value. -The temperature of the exhaust valve is controlled by increasing or decreasing the heat exchange area for the sub-cooled NI material. This allows the exhaust valve to be cooled while monitoring the temperature, thereby preventing overcooling or insufficient cooling.

[Embodiments of the Invention] Hereinafter, a preferred embodiment of the exhaust valve temperature control method for an internal combustion engine according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic longitudinal sectional view showing an example of an exhaust valve device for an internal combustion engine, which is the first step in explaining the method of the present invention.

As for the cooling method, a primary coolant P is sealed in the valve head part 1 in advance, and this vaporized coolant PG is led out from the exhaust valve body 2 and heat exchanged with the secondary cooling US outside to dissipate the heat. The heat syphon principle is applied to indirectly cool the valve head part 1 by returning the condensed secondary coolant P1 into the valve head part 1. On the other hand, a mechanism that simplifies the structure of the heat exchanger 3 and can quickly control the heat exchange area of the heat exchanger 3 in order to maintain the adjustment of the valve head section 1 in an optimal state according to changes in the heat load of the engine. It's Toshide.

As shown in the figure, reference numeral 2 is an exhaust valve body provided in the cylinder head of the engine to close the exhaust valve 1, and the exhaust valve body 2 is integrally formed with a valve shaft 4 at one end thereof. It consists of a valve head part 1.

The inside of the exhaust valve main body 2 is formed hollow along the outer shape, and a coolant chamber 5 is formed in the valve head portion 1 to be filled with cooling water P serving as a primary coolant. Further, a coolant vaporizing chamber 6 is formed in the valve shaft portion 4 and has an upper end open to the outside and a lower end communicating with the coolant chamber 5.
It is designed to accommodate the vaporized coolant (steam) PG rising from the pipe. The valve head portion 1 exposed to a high humidity atmosphere is cooled by the heat of vaporization taken away when the cooling water in the coolant chamber 5 vaporizes, and the vaporized coolant is transferred to the exhaust valve body 2 as described later. It is led out, condensed and liquefied by heat exchange with the secondary coolant S, and returns to the coolant chamber 5 to flow again.

Although not shown, the valve stem 4 is provided with an air spring for urging the exhaust valve body 2 upward and a hydraulic tappet for pushing down against the urging force of the air spring. The exhaust valve main body 2 is driven up and down to open and close the exhaust port.

As a means for guiding the vapor in the coolant vaporizing chamber 6 to the outside and condensing it, a vaporized coolant guide pipe 8 is inserted into the coolant vaporizing chamber 6 from the fixed side while closing the lower open upper end of the coolant vaporizing chamber 6. There is. This guide pipe 8 has one end open and the @ end connected to a connecting pipe 9 extending perpendicularly thereto, and the open end 10 thereof is inserted into the coolant vaporization chamber 6 . In order to seal between the open lower part of the coolant vaporization chamber 6 and the guide pipe 8 while allowing the vertical movement of the exhaust valve body 2 and the rotation for improving the tightness when seated, the inner wall of the open lower part is used. A seal ring 11 made of polyhard rubber is provided.

The connecting pipe 9 is fixed to a cylinder head (not shown),
A heat exchanger 3 for condensing steam through indirect heat exchange with cooling water S serving as a secondary coolant is connected to the end extending at right angles via a bellows joint 12 for absorbing engine vibrations. This heat exchanger 3 has an upper end open to a ladder 13 at the top, a lower end connected to a connecting pipe and a lower end opened to a ladder 14, and a number of condensing pipes 15 standing upright, and covering these condensing pipes 15. A pressure regulating chamber 1 forms a water-cooled layer 16 of a secondary coolant and a pressurized air layer 17 for adjusting its height on the outer periphery of the condensed pipe 15.
It consists of 8. A water supply pipe 19 and a discharge pipe 20 for supplying and discharging cooling water S are provided at the lower part of the pressure regulating chamber 18 on the side of the water cooling layer 16.
are connected. A cooling water pump 21 with a constant rotation speed and a constant discharge amount is connected to the water supply pipe 19, and a bypass pipe 22 connected to the input/output port of this pump 21 is connected to the water supply pipe 19. A flow rate control valve 23 is provided to control the amount of cooling water supplied. The drain pipe 20 is also provided with a throttle valve 24 that controls the amount of cooling water discharged. A predetermined amount of cooling water is supplied to the lower part of the pressure regulating chamber 18 by control with the valve 23. On the other hand, pressurized air A is supplied to the upper part of the pressure regulating chamber 18 on the pressurized air layer 17 side. A compressed air supply pipe 25 is connected, and a compressed air layer 17 is connected to this supply pipe 25.
By controlling the pressure regulating valve 26, the pressure inside the pressurized air layer 17 can be reduced to raise the height of the water cooling layer 16, or conversely, the pressure can be increased to increase the height of the water cooling layer. 16 can be lowered in height. In this case, the rotation speed of the cooling water pump 21 is constant and the discharge amount is also constant, so instead of controlling only the pressure regulating valve 26, the throttle valve 24 and the flow rate IJ Ill are controlled together with the pressure regulating valve 26.
By controlling the valve 23 in conjunction with the valve 23, it becomes possible to easily and stably adjust the height of the water cooling layer 16.

By adjusting the height of the water cooling layer 16 in this way, the contact area (heat exchange area) between the PG on the secondary coolant side and the cooling water S serving as the secondary coolant can be increased or decreased. It has become. -The above pressure regulating valve 26, throttle valve 2
4. The flow control valve 23 constitutes a pressure adjusting means that adjusts the pressure balance between the secondary coolant pressure and the pressurized gas pressure to increase or decrease the heat exchange area of the secondary coolant with respect to the vaporized coolant.

Note that the amount of cooling water can be adjusted by changing the rotational speed of the cooling water pump 21, but in this case, the control on the motor side becomes complicated and the flow of water becomes unstable. Moreover, since the temperature of the steam PG in the condensed pipe 15 is 100° C. or higher and the pressure is higher than atmospheric pressure, there is a risk that the cooling water S will boil when controlling the amount of water that causes a change in water pressure.

Therefore, it is preferable to adjust the height of the cold water tank 16 while the pressure is applied.

Further, 27 is an air vent valve provided in the upper header 13 of the heat exchanger 3.

By the way, various sensors for detecting thermal load are provided in the components of the internal combustion engine such as the exhaust valve body 2. The exhaust valve main body 2 is provided with a valve temperature sensor 30, for example, a thermal lightning pair, for detecting the exhaust valve temperature Tl11 from the valve stem portion 4 along the surface of the valve head portion 1. The vaporized coolant guide pipe 8 is provided with a vapor temperature sensor 31 for detecting the vapor temperature Tv of the coolant vaporizing chamber 6, such as a thermal lightning pair, and a pressure sensor 32 for detecting the vapor pressure P of the same chamber 6. It is being

Further, the heat exchanger 3 is provided with a water level sensor 33 for detecting the cold water tank water level H. This water level sensor 33 is
An upright water level pipe 34 communicates with the outside of the pressure regulation chamber 18 at its upper and lower parts and has a double layer of a pressurized air layer 179 and a water cooling layer 16 formed therein, similar to the pressure regulation chamber 18; A scale 37 is inserted into this water level pipe 34 from above through a seal ring 35 and moves up and down according to the water level of the water cooling layer 16 by a float 36 installed at the lower end.
A photoelectric lamp 38 reads the graduations of this scale 37.
The height of the water cooling layer 16 can be detected at all times.

As shown in FIG. 2, a rotation sensor 40 that detects the engine rotation speed N from the rotation of the crankshaft gear 39 and a rack position sensor 42 that detects the position of the fuel rack 41 are provided, both of which are photoelectrically operated. It consists of lamps, etc.

These valve temperature sensors 3O1, the temperature sensor 31, the pressure sensor 32, the water level sensor 33, the rotation sensor 4O, and the rack position sensor 42 are electrically connected to the control unit 43 as shown in FIG. A temperature signal, a steam pressure signal, a water cooling layer level signal, an engine rotation speed signal, and a rack position signal are input to the control section 43. A data setting device 44 is connected to the control section 43, and inputs data values necessary for obtaining a predetermined exhaust valve temperature value 10- and an optimum exhaust valve temperature into the control section 43 in advance. The output side of the control section 43 is connected to the pressure regulating valve 26, the throttle valve 24, the flow rate control valve 23, and the air vent valve 27, and the operation of these valves is controlled by issuing an operation command signal.

Here, the functions of the control section 43 will be explained. Control unit 4
3, when the pressurized air pressure of the heat exchanger 3 is changed to increase or decrease the heat exchange area, and when the height of the water cooling layer 16 is adjusted,
The exhaust valve temperature is controlled in response to this, and the relationship between the exhaust valve temperature and the pressurized air pressure, in other words, the height of the water cooling layer 16 and the pressurized air pressure are the exhaust valve temperature or the steam temperature. , steam pressure, gas temperature in cylinder, exhaust gas dryness,
It is related to engine speed, fuel rack position, etc.

All values except the exhaust valve temperature correspond to the exhaust valve temperature singly or in combination. Therefore, the temperature of the exhaust valve main body 2 can be controlled by directly or indirectly detecting the exhaust valve temperature using the various sensors described above and controlling the pressure regulating means based on the detected value.

Fluctuations in these values detected by various sensors mean heat load fluctuations in the internal combustion engine of the present invention. Specifically, the functions of the control section 43 will be explained. There are two functions, a fixed value control function and an arbitrary control function, and these are selectable.

First, the fixed control function controls the pressure regulating valve 26 and the like in order to keep the detected value at a preset desired constant value.

Taking the exhaust valve temperature Tm as an example, a desired exhaust valve temperature Tlll0 is input in advance to the control unit 43 via the data setter 44 and stored.

Then, the exhaust valve temperature signal detected from the valve temperature sensor 30 is converted into temperature, and the converted exhaust valve portion iTi+ is compared with a desired exhaust valve temperature 1mo.

If Tm<Tm0, the cooling is too much, so pressure regulating valve 2
6 is opened, while an operation command signal is issued to the pressure regulating valve 26, the flow rate control valve 23, and the throttle valve 24 in order to operate the flow rate control valve 23 and the throttle valve 24 in the direction of closing them. On the other hand, T
ll1>TI! If it is 10, there is insufficient cooling, so an operation command signal is issued to the pressure regulating valve 26 to close it and to the flow rate control valve 23 and throttle valve 24 to open them. Also below 1ji Tlll0
In this case, the operation of the joint venture will be stopped at that point.

Note that the case where the steam pressure is 1] and the cold water layer level H is exactly the same as the above case. Among these, the cold water layer level signal has a function as a feedback signal, so it is used to issue a warning if the height of the cold water layer 16 does not change even if the joint venture controlled by the control unit 43 is activated. It can also be done.

Next, the optional control function is to control the pressure regulating means so as to change the exhaust valve temperature Tl11 in accordance with the engine load. That is, when the engine load fluctuates, the amount of heat generated changes, so the temperature difference within the exhaust valve body 2 changes significantly. Therefore, the thermal stress also changes significantly. Therefore, in order to protect the exhaust valve body 2, it is necessary to control the temperature level of the exhaust valve body 2 within a certain range and to a temperature level that minimizes the generation of thermal stress.

Therefore, a relational expression between the engine output and the measured exhaust valve temperature is created in advance based on experiments or the like, and this is controlled via the setting device 44 as the optimum exhaust valve humidity data for the engine output. The information is stored in the section 43. Since the engine output, that is, the load, is approximately determined by the engine rotation speed N and the fuel rack position, these signals detected from the rotation sensor N and rack position sensor L are converted into their respective physical units, and the converted measurement The values N and L are first compared with the stored desired values No and Lo, and the comparison is repeated until they match. If they match, the optimum exhaust valve concentration T at that time is stored in advance.
mo (or the above temperature Tvo, water cooling layer water cooling 1''). Then, compare this optimum exhaust valve temperature Tlll0 with the actual exhaust valve temperature Tm obtained from the valve temperature sensor 30, and then set the exhaust valve temperature T11 to the optimum exhaust valve temperature as in the fixed value control function. The pressure regulating valve 26, the flow rate control valve 23, and the throttle valve 24 are controlled.

In particular, unlike the valve temperature sensor 30, steam temperature sensor 31, pressure sensor 32, etc., which are directly subjected to thermal stress, the water level sensor 33 is not affected by heat and is therefore less likely to be damaged.

Therefore, even if the valve temperature sensor 30 or the like is damaged, the optimum water cooling layer 16 for the engine output can be determined in advance based on the water cooling layer water level 14- signal from the water level sensor 33 and the engine load signal from the rotation sensor ++-40 and rack position sensor 42. By storing the height of the pressure as data, it is possible to control a similar pressure adjustment membrane.

In order to smoothly adjust the pressure based on the above-mentioned sieving process in the control unit 43, the control unit 43 outputs an operation command signal to the air vent valve 27 as necessary to adjust the amount of air in the heat exchanger 3. It is supposed to be done.

The operation of this embodiment having the above configuration will be described.

When the valve head portion 1 is heated by the exhaust gas in the valve operating state in which the exhaust valve body 2 is rotating and moving up and down, the temperature of the cooling water P in the coolant chamber 5 rises, and when it vaporizes, it absorbs heat from the surroundings. to cool the valve head part 1. Then, this vaporized steam PG rises in the coolant vaporization chamber 6, passes through the guide pipe 8 and the connecting pipe 9, and reaches the condensed pipe 15 of the heat exchanger 3, where the cooling water in the pressure regulation chamber 18 It is condensed and liquefied through indirect heat exchange with S.

The liquefied cooling water PL flows down the connecting pipe 9 and the guide pipe 8, flows back into the coolant chamber 5, and repeats the cycle of vaporizing again. In this cycle, when the engine load fluctuates, these physical units are determined from various signals from the valve temperature sensor 30, steam temperature range 31, pressure sensor 32, water level sensor 33, rotation range 40, and rack position sensor 42. The control unit 43 performs the conversion and compares these converted values with corresponding values input in advance. This comparison may be performed for all heat load elements depending on the control level and required standards, or may be limited to only one, for example, only the exhaust valve temperature Tm. Based on the comparison result, the control unit 43 controls the pressure regulating valve 26, the flow rate control valve 23, and the throttle valve 2 so that the exhaust valve temperature Tm becomes a desired constant value or an optimal exhaust valve temperature.
4, an operation command signal in the opening direction or the closing direction is output. now,
Taking the exhaust valve temperature Tll+ as an example, 7m is too cold.
If <Tmo, the control unit 43 operates to open the pressure regulating valve 26 and close the flow rate control valve 23 and the throttle valve 24. These operations increase the amount of pressurized air in the pressure regulation chamber 18, increasing the pressurized air pressure, which overcomes the pressure of cooling water, which is the secondary coolant, and suppresses its inflow into the pressure regulation chamber 18. , the height of the water cooling layer 16 is reduced. Therefore, the contact area of the vaporized coolant PG with the secondary coolant S decreases, the heat exchange rate in the heat exchanger 3 decreases, and the amount of condensed and liquefied vaporized coolant PG decreases. As a result, the coolant chamber 5
The liquefied secondary coolant PL flowing back into the exhaust valve body 2 for cooling is reduced, the cooling of the exhaust valve body 2 is suppressed, and its temperature is increased, thereby making it possible to control the exhaust valve temperature Tl11 to a desired value. can. On the other hand, if Tm>Tm0, cooling is insufficient this time, so the control unit 43 controls the pressure adjustment means to increase the heat exchange area of the cooling water S with respect to the steam PG. As a result, the amount of condensation and liquefaction increases, and the exhaust valve main body 2 is further cooled to lower its temperature, thereby making it possible to control the exhaust valve temperature TI to a desired value.

In this way, according to the above embodiment, the exhaust valve temperature of the engine can be maintained at a constant temperature or an optimum temperature according to changes in heat load (exhaust valve temperature, steam temperature, engine fan rotation speed, rack position, etc.). Therefore, the exhaust valve can be controlled to a desired temperature regardless of fluctuations in heat load. As a result, sulfuric acid corrosion under low loads, vanadium corrosion under high loads, etc. can be effectively avoided, and the service life can be dramatically improved. Furthermore, since the exhaust valve can be controlled to a desired temperature even in response to changes in heat load, changes in temperature of the valve head portion 1 can be reduced. As a result, changes in thermal stress applied to the valve head portion 1 are reduced, making it possible to sufficiently withstand high-temperature fatigue, and significantly improving lifespan and reliability.

Furthermore, since the exhaust valve temperature is sufficiently appropriate even in a high heat load atmosphere, the high temperature strength of the material is sufficiently high.

Therefore, expensive materials for the exhaust valve, e.g.
There is no need to use c80A or the like; conventionally used heat-resistant alloys are sufficient.

On the other hand, foreign matter generated by combustion adheres to the valve seat surface particularly at high temperature levels and damages the valve seat surface. This is because even if the material is made of expensive material with high temperature strength, the valve seat surface will still become hot, so the situation is the same. However, according to this embodiment, since the temperature of the exhaust valve can be controlled to be below the temperature at which foreign matter adheres, such scratches can be avoided, and from this point of view as well, the life of the exhaust valve can be improved.

In addition, the relationship between the heat load of the engine and the exhaust valve temperature (temperature level and thermal stress level) can be estimated in advance by calculation, and the exhaust valve temperature, steam temperature, steam pressure, etc. during actual operation can be controlled using this calculated value. Since the comparison can be made in the section 43, the cooling temperature control is accurate and easy.

In addition, since the cooling water outlet temperature of the heat exchanger 3 is 100° C. or higher, the exhaust heat can be utilized.

In addition, in the one in Figure 1, the vaporized secondary coolant PG entering the heat exchanger 3 and the condensed secondary cooling UPL coming out of the heat exchanger 3 pass through the same passage, but it is necessary to separate them. You may also communicate through

That is, the heat exchanger 3 in FIG. 4 includes a condensing chamber 70 that accommodates steam PG rising from a communication pipe 9 and condenses it into liquid, and condensing tubes 71 arranged horizontally and in multiple stages within this condensing chamber 70. , consisting of pressure regulating chambers (not shown) provided before and after the condensing chamber 70 (in the front and back directions of the page) to which the condensing pipe 71 is connected. A water-cooled layer of the secondary coolant S and a pressurized air layer that pressurizes the secondary coolant S are formed in this pressure regulating chamber, and cooling water at a constant pressure is supplied and discharged to the water-cooled layer through a water supply pipe 63 and a drain pipe 64. , pressurized air is supplied to the pressurized air layer through a compressed air supply pipe 65. By adjusting the pressure balance between cooling water and pressurized air, the number of condensing pipes 71 filled with cooling water is increased or decreased, and as a result, as in the case of Fig. 1, primary cooling and secondary cooling It is possible to change the contact area with the coolant.

In such an external condensing type heat exchanger 3, the condensing pipe 71 provided in the condensing chamber 70 is tapered along the flow of the steam PG so that the steam PG and the condensate PL do not flow together. The sides are lowered and the whole structure is slanted. The connecting pipe 9 and vaporized coolant guide pipe 8 connected to the heat exchanger 3 are also steam PG.

and the condensate PL are separated so that they do not mix.

Separation means for the connecting tube 9 is achieved by dividing the connecting tube 9 into upper and lower sections using a partition plate 72, with the upper section serving as a passage for steam and the lower section serving as a passage for condensate. Further, the separation means of the guide tube 8 has a double-tube structure, with the inner tube 73 serving as a passage for the steam PG, and the outer tube 74 serving as a passage for the condensed liquid PL. It is difficult for steam PG to enter the lower end of the outer tube 74, and condensate P
It is filled with a porous substance 75 such as sintered alloy or steel wool so that L can easily come out.

Further, the inner pipe 73 itself has a double pipe structure so that the steam PG rising therein is not cooled by the condensate.

Therefore, the steam and condensate are completely separated, so that the condensing capacity of the heat exchanger 3 can be significantly improved. Also, since the guide tube 8 will come into contact with the condensate PL, it can be expected that the wetness m of the steam PG will be lower.
This lower temperature has the advantage that the seal ring 11 (see FIG. 1) in contact with the guide tube 8 does not reach a high temperature, and the life of the seal ring 11 is improved.

[Effect of the invention] In summary, according to this invention, the following advantages 21- It has a great effect.

(1) The temperature of the exhaust valve is controlled by detecting the heat load fluctuation of the internal combustion engine and increasing or decreasing the heat exchange area of the secondary coolant to the vaporized secondary coolant according to the detected value. The exhaust valve temperature can be accurately controlled and stabilized regardless of heat load fluctuations.

(2) By stabilizing the exhaust valve temperature, it is possible to prevent overcooling or insufficient cooling of the exhaust valve temperature, effectively avoiding metal corrosion and damage caused by these, and improving the reliability of the exhaust valve temperature and the lifespan. This allows the internal combustion engine to be operated safely.

[Brief explanation of drawings]

The figures are views showing a preferred embodiment of an exhaust valve device for an internal combustion engine according to the present invention, in which FIG. 1 is a schematic vertical sectional view of the entire device according to the first embodiment, and FIG. 2 is a rotation sensor and a rack. FIG. 3 is a block diagram showing the input/output system of the control section, and FIG. 4 is a schematic vertical sectional view of the heat exchanger 22 and its surroundings according to the second embodiment. In the figure, 2 is the exhaust valve body, 3 is the heat exchanger, and P
is the primary coolant, PG is the evaporative coolant, PL is the condensing coolant, and S is the secondary coolant. Patent applicant: Patent attorney representing Ishikawajima-Harima Heavy Industries Co., Ltd.
Nobuo Kinutani 23-

Claims (1)

[Claims] In the exhaust valve of an internal combustion engine that has a closed thermosiphon pipe, the vaporized secondary coolant drawn out from inside the exhaust valve is condensed by indirect heat exchange with the secondary coolant, and this condensed secondary coolant is When the exhaust valve is returned to the exhaust valve, the humidity of the exhaust valve is controlled by detecting the heat load fluctuation of the internal combustion engine and increasing or decreasing the heat exchange area of the secondary coolant with respect to the vaporized-secondary coolant according to the detected value. An exhaust valve temperature control method for an internal combustion engine, characterized in that: