JPH0648088Y2 - Lubricating oil cooling structure in engine - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Field of Industrial Application) The present invention relates to an engine, and more particularly to a structure for cooling lubricating oil supplied to each sliding portion of the engine.

(Prior Art) In a vehicle engine such as an automobile, a predetermined amount of lubricating oil is constantly circulated and fed to a crank / piston system on the cylinder block side and a valve operating system on the cylinder head side. That is, the lubricating oil is pumped up by an oil pump from an oil pan integrally provided at the lower end of the cylinder block, and is guided to a main gallery integrally formed on the cylinder block. From here, a part of the lubricating oil is applied to the lubrication of the crank system such as the crank bearing and the crank pin, and the other part is applied to the lubrication of the piston system such as between the piston and the cylinder bore. Still another part is raised to the cylinder head side and applied to lubrication of the valve train. Then, the lubricating oil that has finished lubrication of the crank system and the piston system is directly returned to the oil pan, and the lubricating oil that has finished lubrication of the valve operating system is dropped from the cylinder head side to the cylinder block side and again in the oil pan. It is stored. Such a lubricating oil circulation path is provided in the engine.

The lubricating oil is constantly replenished and circulated to each sliding portion including the rotating portion of the engine to reduce frictional resistance and ensure smooth operation, as well as to cool the lubricating portion and prevent corrosion.
Alternatively, it plays a role of maintaining airtightness of the combustion chamber.

In this way, the lubricating oil has a more effective sliding effect, that is, even if there is a very small roughness on the sliding surface, the solid friction between the sliding surfaces does not occur, and the lubricating oil is not generated between the sliding surfaces. An oil film with a proper thickness must be formed.

To do this, it is necessary to select a lubricant with appropriate characteristics,
Conditions such as viscosity, anti-wear properties, heat and oxidation safety are considered.

(Problems to be solved by the invention) By the way, it is common to say that no matter what characteristics are selected for the lubricating oil, the lubricating oil must be within the range where the oil temperature does not exceed the allowable operating temperature. Moreover, the temperature should be as high as possible before use. That is, when the engine is driven in an extremely low temperature environment, the oil temperature of the lubricating oil is unlikely to rise, so that the friction (friction loss) becomes large while the viscosity of the lubricating oil remains high. On the other hand, when the engine is driven at extremely high temperatures and the oil temperature of the lubricating oil rises above the allowable operating temperature, the lubricating oil deteriorates rapidly,
Lubrication is lost. Therefore, if the oil temperature is set within the range not exceeding the allowable operating temperature of the lubricating oil and at the allowable operating temperature or at a temperature as high as possible close to the allowable operating temperature, the viscosity of the lubricating oil is reduced and friction is reduced.
Generally, the allowable operating temperature of lubricating oil is approximately 120 ° C, and the temperature at which rapid deterioration occurs is approximately 140-150 ° C.

Even at normal temperature, if the engine is driven at high rotation speed for a long time, it is inevitable that the oil temperature of the lubricating oil rises. Some engines are roughly divided into those that have no cooling function for lubricating oil or those that have a water-cooled oil cooler. FIG. 4 shows temperature characteristics of engine cooling water and lubricating oil with respect to engine speed. In the figure, the broken line change A is the temperature characteristic of the engine cooling water, and since the heat is radiated by the radiator, the change in temperature rise is relatively small. The one-dot chain line change B is a lubricating oil characteristic used in an engine equipped with a water-cooled oil cooler in the oil circulation path. Even if the engine speed exceeds about 6000 rpm, the allowable operating temperature of the lubricating oil is still up to 120 ° C. It will never rise. This allowable operating temperature is reached when the engine speed rises to the so-called red zone, and therefore the lubricating oil does not deteriorate. However, in this case, the lubricating oil is always cooled even within a range not exceeding the allowable operating temperature, and the oil temperature is often lowered to deviate from the optimum operating range. Hard to say. A two-dot chain line change C is a temperature characteristic of lubricating oil used in an engine having no oil cooler in the oil circulation path. Since the lubricating oil naturally radiates heat during circulation, the oil temperature rises almost linearly. Then, when the engine speed reaches about 6000 rpm, the oil temperature exceeds the allowable operating temperature of 120 ° C and rises as it is. Therefore, the lubricating oil used for engines without such an oil cooler is
It will deteriorate immediately.

The present invention has been made by paying attention to the above circumstances. The lubricating oil is constantly maintained at an allowable operating temperature or a high oil temperature close to the allowable operating temperature to supply oil to each sliding portion. It is an object of the present invention to provide a lubricating oil cooling structure for an engine, which enables control of the oil temperature of the engine and achieves a high level of lubricating characteristics.

[Constitution of device]

(Means and Actions for Solving the Problem) That is, the present invention is provided with an oil pan for collecting lubricating oil in the lower part of a cylinder block and a cylinder in the upper part, and the water is provided along the cylinder outer peripheral part of the cylinder block. A jacket is provided, an oil circulation path is provided for sucking up the lubricating oil in the oil pan and supplying it to each sliding part, and for returning it to the oil pan in order. One end of the heat pipe is inserted into the water jacket. The other end is fitted in the middle part of the oil circulation path, and the heat pipe has a temperature switch function that acts as a heat pipe only when the lubricating oil in the oil circulation path reaches a predetermined temperature or higher. A lubricating oil cooling system for an engine, characterized in that heat of the lubricating oil in the oil circulation path is conducted to a water jacket to cool the lubricating oil, and the oil temperature is always maintained at a substantially predetermined temperature. It is a construction.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.
A cylinder block 1 shown in FIG. 1 is mounted on the upper end of a cylinder head (not shown) to form an engine body. The upper part of the cylinder block 1 is a cylinder 2, and the piston 3 is placed in the cylinder bore 2a.
Is slidably inserted. Further, a skirt 4 is integrally connected to the lower portion of the cylinder 2, and a crank cover 5 is integrally assembled to the lower portion. Bearing members 7a, 7b for rotatably supporting the crankshaft 6 are integrally formed in the skirt 4 and the crank cover 5. An oil pan 8 is attached to the lower part of the crank cover 5,
A reservoir 9 for collecting the lubricating oil is formed. This reservoir 9
Oil pump 10 is immersed in the lubricating oil of the oil strainer attached to the outer side of the crank cover 5.
11 and a high-pressure oil pipe 12 communicate with each other. Further, the oil strainer 11 communicates with a main gallery 14 provided on the outer peripheral portion of the lower end of the cylinder 2 via a high pressure oil passage 13. That is, when the oil pump 10 is driven, the lubricating oil in the oil pan 8 is guided to the oil strainer 11 via the high pressure oil pipe 12, filtered there, and then filtered through the high pressure oil passage 13 to the main gallery 14. It is supposed to be sent to. The main gallery 14 and the cylinder head communicate with each other via an upper oil circulation system (not shown) so that oil can be supplied to a cam shaft of a valve operating system provided in the cylinder head. Also, from the main gallery 14 again, the crankshaft 6 and its bearing members 7a, 7b
The lubricating oil is supplied to the piston system such as the crank system, which is the sliding part between the piston 3 and the cylinder, the sliding part between the piston 3 and the cylinder bore 2a, and the sliding part between the piston 3 and the connecting rod 15. Will be cooled. After lubricating oil is supplied to lubricate each sliding portion or is used for cooling, all the lubricating oil returns to the oil pan 8 again and collects in this way. Oil circulation
16 are formed.

On the other hand, a water jacket 17 is integrally provided above the outer peripheral surface of the cylinder 2, and an oil jacket 18 is integrally provided below the water jacket 17. The water jacket 17 has an upper end surface opened so as to communicate with the water jacket provided on the cylinder head. Further, attachment mouths 17a and 18a are integrally formed on the peripheral surface portions of the water jacket 17 and the oil jacket 18 which face each other, and these opening surfaces are attached to a heat pipe 19 described later. The flanges 20a, 20b are closed tightly. One end of the oil supply pipe 21 is fitted and inserted into the flange 20b on the oil jacket 18 side, and the tip end thereof is opened in the oil jacket 18. The other end of the oil supply pipe 21 opens into the main gallery 14, and an oil pressure regulator 22 is connected to the middle portion thereof.
The oil pressure regulator 22 is a main gallery.
The oil pressure of the lubricating oil sent from the oil supply pipe 21 from 14 is sensed, and when the oil pressure exceeds a predetermined value, the oil pressure is released to supply the lubricating oil to the oil jacket 18. In addition, the oil pressure of the lubricating oil pumped from the oil pump 10 increases as the engine speed increases. However. Since the amount of the lubricating oil supplied to each sliding part including the valve operating system does not change, the oil pressure of the lubricating oil introduced from the main gallery 14 to the oil supply pipe 21 rises as the engine speed increases. . The oil pressure regulator 22 is normally set to open at the hydraulic pressure of the lubricating oil that is pumped when the engine speed is about 6000 rpm, and to close at the hydraulic pressure below that speed. On the other hand, an overflow pipe 23 connects the upper end of the skirt 4 and the oil jacket 18. This overflow pipe
Reference numeral 23 is for overflowing the lubricating oil introduced into the oil jacket 18 into the skirt 4 when the lubricating oil reaches a predetermined amount. The returned lubricating oil is finally collected in the reservoir 9 of the oil pan 8.

Next, the heat pipe 19 with the temperature switch function will be described. This is a known heat pipe called a variable conductance heat pipe (VCHP for short). A feature of this type of heat pipe compared to other pipes is that it keeps the temperature of the heat generating component attached to the evaporation part almost constant regardless of the amount of heat generated by the heat generating component. Having such a temperature control function
Initially, a non-condensable gas was generated inside the heat pipe made of a combination of sodium and stainless steel, which was discovered in the subsequent study process. In other words, when the evaporation part of the heat pipe is heated, the generated hydrogen gas collects in the condensing part and reaches a gas equilibrium state. Since the vapor of the working fluid and the non-condensable gas are separated from each other, there is a clear boundary surface between the two, and the non-condensable gas effectively blocks the occupied condensing part and locally Stop heat transfer. The position of the boundary surface moves according to the amount of thermal energy transmitted. Therefore, by selecting the position of the gas boundary surface appropriately, the temperature of the heat receiving part can be kept within a narrow temperature range.

The operating principle of such a temperature switch function is
This can be explained based on the drawings (A) and (B). As shown on both sides, the lower end evaporation part of the heat pipe P is inserted into the oil tank A filled with oil, the upper end condensation part is inserted into the water tank B filled with cooling water, and the oil tank A is inserted.
The oil inside is heated by a heating body (not shown). In the figure (A),
The heat pipe P is in an internal state where the oil temperature is, for example, about 100 ° C., and the saturated vapor pressure of water, which is the working liquid enclosed therein, is low, so that the effective condensation length is short. The condensing part on the cooling water side is filled with N ₂ gas, which is a non-condensable gas, so at the above oil temperature, there is no vapor condensing action from where the gas interface does not reach the condensing part, and latent heat of vaporization is taken from the oil. Nothing. The so-called heat pipe function is not exerted, and therefore the temperature rise similar to the change without the oil cooler described above with reference to FIG.

As shown in FIG. 3B, when the oil temperature rises to, for example, about 130 ° C., the vapor pressure of the working fluid rises, compressing the N ₂ gas and reducing the gas volume. As a result, the effective condensing unit length increases, and the condensing unit exchanges heat with the cooling water in the water tank B to condense. This condensate returns to the evaporator and evaporates again, removing latent heat of vaporization from the oil. That is, the heat pipe action is not achieved until the oil temperature is increased, and the oil is cooled to prevent the oil temperature from rising. Also, if the oil temperature decreases, the vapor pressure decreases, the N ₂ gas expands, and the effective condensing part length decreases, so that no heat conduction action is performed again.

Fig. 3 shows the external shape of the heat pipe 19 with a temperature switch function that is actually used. That is, as described above, it is a sealed cylindrical body having a certain thickness and formed in a substantially U shape, and the working liquid and the non-condensable gas are enclosed therein. Further, flanges 20a, 20b for closing the opening surfaces of the attachment ports 17a, 18a of the water jacket 17 and the oil jacket 18 are integrally attached to the upper piece and the lower piece, respectively. This is also as described above.

Then, as the engine is driven, oil is supplied to each sliding portion, and the oil temperature of the lubricating oil rises. As shown in FIG. 5, the oil temperature change D increases proportionally until the engine speed reaches about 6000 rpm. That is, as shown in FIG. 1 again, the oil pressure regulator 22 is
Since the hydraulic pressure of the lubricating oil guided from the oil pump 10 through the main gallery 14 has not reached the set pressure, the valve is closed. Therefore, since there is no supply of lubricating oil to the oil jacket 18 and the oil temperature does not rise, the heat pipe
19 does not have any heat conduction effect. In this way, there is no cooling effect on the lubricating oil, and the temperature rise is exactly the same as the two-dot chain line change C described above with reference to FIG.

When the engine speed further increases and reaches about 6000 rpm, the oil pressure regulator 22 is opened and the lubricating oil is guided to the oil jacket 18 when the hydraulic pressure reaches the set pressure. At this time, if the oil temperature is equal to or higher than a predetermined temperature, the temperature switch function of the heat pipe 19 operates, and the heat of the lubricating oil is taken by the cooling water of the water jacket 17 to decrease. Again, as shown in Fig. 5, the oil temperature of the lubricating oil is about 120 ° C.
The oil temperature does not change even if the engine speed is increased. Therefore, the lubricating oil is constantly cooled and maintained at the allowable operating temperature or a high temperature close to it. In a state where the oil is returned to the oil pan 8 again via the overflow pipe 23 and then oil is supplied to each sliding portion, the viscosity is lowered to reduce friction, and an extremely efficient lubricating action is obtained.

In the above embodiment, the oil jacket 18 for inserting the one-end evaporating portion of the heat pipe 19 is provided on the outer peripheral portion of the cylinder 2. However, the present invention is not limited to this, and the cross-sectional area of the main gallery 14, for example, may be changed. The heat pipe 19 may be made larger, and the evaporating portion at one end thereof may be fitted therein, or it may be immersed in the lubricating oil collected in the reservoir 9 of the oil pan 8. The point is that there is no problem in providing it in the middle of the oil circulation path 16 as long as space is provided.

Further, the shape structure of the cylinder block 1 and the heat pipe 19 is not limited to the above-mentioned embodiment, and it is needless to say that various modifications can be made within the scope of the present invention.

[Effect of device]

As described above, according to the present invention, by using the heat pipe with the temperature switch function, each sliding part is kept in a state where the oil temperature of the lubricating oil is always maintained at the allowable operating temperature or a high oil temperature close to it. It is possible to refuel. In other words, the oil temperature of the lubricating oil is controlled to bring about the effect of raising the level of this lubricating characteristic.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of an essential part of an engine showing an embodiment of the present invention, FIGS. 2 (A) and 2 (B) are diagrams for explaining the operating principle of a heat pipe with a temperature switch function, and FIG. Fig. 4 is a perspective view of the heat pipe, Fig. 4 is a temperature characteristic diagram of lubricating oil used for engines with engine cooling water and a water-cooled oil cooler and lubricating oil used for engines without an oil cooler with respect to engine speed, and Fig. 5 is the present invention. FIG. 3 is a temperature characteristic diagram of the lubricating oil used in the engine with the heat pipe with respect to the engine speed. 8 …… Oil pan, 2 …… Cylinder, 1 …… Cylinder block, 17 …… Water jacket, 16 …… Oil circulation path, 19 ……
heat pipe.

Front page continuation (72) Inventor Ren Hirako 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Inventor Masatoshi Ninoyu 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Industrial Co., Ltd. (72) Inventor Yasuyuki Makikawa 8-1-1 Tsukaguchihonmachi, Amagasaki, Hyogo Sanryo Electric Co., Ltd. Industrial Systems Research Institute (72) Inventor Masao Fujii 8-1-1 Tsukaguchihonmachi, Amagasaki, Hyogo No. Sanryo Electric Co., Ltd. Central Research Laboratory (72) Inventor Hitoshi Inoue 1-2-2 Wadasaki-cho, Hyogo-ku, Kobe, Hyogo Prefecture Mitsubishi Electric Co., Ltd. (56) References JP, U)

Claims (1)

[Scope of utility model registration request] 1. A cylinder block having an oil pan for collecting lubricating oil at its lower portion and a cylinder at its upper portion, a water jacket provided along the cylinder outer peripheral portion of the cylinder block, and an inside of the oil pan. The oil circulation path that sucks up the lubricating oil from the engine and supplies it to the sliding parts of the engine and returns it to the oil pan in order, one end of which is in the water jacket and the other end is in the middle of the oil circulation path. The heat pipe function works only when the temperature of the lubricating oil in the oil circulation path rises above a certain temperature and the heat of the lubricating oil in the oil circulation path is guided to the water jacket to cool the lubricating oil and increase the oil temperature. A lubricating oil cooling structure for an engine, comprising: a heat pipe having a temperature switch function for always maintaining a substantially predetermined temperature.