JP3063104B2 - Alcohol engine lubrication system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a lubricating device for an alcohol engine using alcohol as a fuel.

[Conventional technology]

Conventionally, in a two-cycle engine, an exhaust valve is arranged in an exhaust port formed in a cylinder head, or exhaust holes are provided in the entire circumference of the cylinder liner, and scavenging holes are provided in the entire circumference of the cylinder liner. There is a uniflow scavenging type in which the scavenging efficiency and the intake efficiency are increased by preventing the exhaust gas from being disturbed, and the asymmetric scavenging type is capable of performing the rear intake.

By the way, when configuring a two-stroke engine, there is a type in which a crankcase functions as a compressor. Such a two-cycle engine is disclosed, for example, in Japanese Patent Application No. 1-182452 filed by the present applicant.

Also, environmental pollution due to exhaust gas exhausted from a vehicle engine has become a problem, and alcohol engines have recently attracted attention. In an alcohol engine,
The content of carbon dioxide and carbide in the exhaust gas is gasoline,
It is much less than fuel such as light oil.

However, in a two-cycle alcohol engine using alcohol fuel, there is a problem that ignitability deteriorates. In other words, alcohol has a higher latent heat for vaporization than gasoline, light oil, etc. For example, alcohol requires a vaporization latent heat of 5% of fuel while gasoline requires a vaporization latent heat of 0.7% of fuel. This is because alcohol fuel has a property that it is difficult to vaporize. In addition, the alcohol fuel injected from the alcohol injector, ie, the fuel injection nozzle, into the compressed air in the intake passage or the combustion chamber lowers the temperature of the compressed air or the combustion chamber wall due to vaporization, thereby deteriorating the ignition.

Therefore, in an insulated engine using alcohol as fuel,
If the entire engine body is heated to a high temperature and heat is taken from the high-temperature wall to vaporize the inhaled alcohol fuel, the latent heat of vaporization is provided, so that the vaporization of the alcohol fuel is promoted and a good mixture is obtained. Will be generated.

[Problems to be solved by the invention]

However, when the temperature of the entire engine is raised to a high temperature, oil cannot be stored in the crank chamber. Usually, in such a two-stroke engine, the crank journal of the crank shaft, the large diameter portion of the connecting rod and the small diameter portion of the connecting rod are generally used. Various measures have been taken for the lubrication system for lubricating the rotating sliding parts. Further, if the temperature of the sliding portion becomes high with respect to the sliding motion between the piston ring and the cylinder liner, the problem of seizure occurs. Accordingly, the present applicant has developed an alcohol insulated engine previously filed as Japanese Patent Application No. 1-182455 for a lubrication system for a sliding portion of an alcohol engine.

Further, in a two-cycle alcohol engine, water easily dissolves in the alcohol fuel, so rust and corrosion occur in the fuel system or the fuel supply system, and troubles and the like are likely to occur. Further, in the alcohol engine, since a large amount of water is generated by combustion, there is a problem that a sliding trouble easily occurs in the combustion chamber or the cylinder liner.

On the other hand, the use of alcohols such as methanol as a fuel, due to the low combustion temperature, fewer emissions NO _X, and there is no discharge of the smoke, emission of CO ₂ is compared to petroleum fuels, reduced by half, low It has ideal characteristics as a pollution engine. Therefore, for the alcohol engine, it is important for the development of a methanol engine to eliminate the above-mentioned disadvantages among the above-mentioned characteristics.

However, when operating in two cycles using methanol fuel in an alcohol engine, the scavenging of the crankcase causes methanol to enter the bearing system, piston, piston ring, and other parts, and the lubrication system deteriorates extremely. , The reciprocating motion of the piston, the sliding motion of the sliding portion, etc. cannot be continued. By the way, the viscosity of methanol is 0.
It is 6 centistokes, and considering the load condition of the engine, it is not possible to maintain a good fluid lubrication state with an alcohol engine. Further, when a general lubricating oil is used as a lubricating material in a sliding portion of an alcohol engine, the oil enters the combustion chamber and burns, thereby giving adverse effects such as generation of hydrocarbons.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems. In an alcohol engine using an alcohol fuel, it is possible to prevent troubles such as rust and corrosion due to moisture generated by combustion, and to provide a bearing system, a piston, and a piston for alcohol. In order to prevent intrusion into parts such as rings, general lubricating oil is not used as a lubricant to be supplied to sliding parts such as cylinder liners, crankshafts, connecting rods, etc. Uses a light oil with a relatively high viscosity of 3.8 centistokes and low vaporization, but a high cetane number. The light oil itself has a lubricating function and easily burns even if light oil is mixed into the combustion chamber. Therefore, it is possible to reduce the adverse effect of burning with fuel alcohol and deteriorating exhaust gas. Providing a lubricating device for an alcohol engine that can form a coating layer of solid lubricant such as CaF on the sliding surface between the liner liner and reduce the coefficient of friction during boundary lubrication to avoid adhesion at the sliding part It is to be.

[Means for solving the problem]

The present invention is configured as follows to achieve the above object. That is, the present invention provides a solid lubricant coating layer formed on each sliding surface of a ceramic piston ring and a ceramic cylinder liner, and a cylinder opened on the sliding surface for supplying a lubricating liquid to the sliding surface. A lubricating fluid passage communicating with a number of through holes formed in a peripheral direction of a lower portion of the liner, a lubricating fluid passage for supplying the lubricating fluid to a sliding portion between a crankshaft and a connecting rod, and supplying the lubricating fluid to each of the lubricating fluid passages The present invention relates to a lubricating device for an alcohol engine, comprising a pump, using alcohol as fuel, and using light oil as the lubricating liquid supplied by the pump.

The lubricating device for an alcohol engine uses CaF as the solid lubricant constituting the coating layer.

[Action]

Since the lubricating device for an alcohol engine according to the present invention is configured as described above, when the engine is partially loaded, the sliding surface between the cylinder liner and the piston ring and the sliding portion between the crankshaft and the connecting rod are preferably filled with the lubricating liquid. If the combustion chamber becomes hot when the engine is under heavy load, the solid lubricant layer such as CaF formed on the sliding surface between the piston ring and the cylinder liner The function reduces the coefficient of friction during boundary lubrication, achieves good lubrication, and avoids adhesion.

In particular, since the lubricating system of this alcohol engine uses light oil as the lubricating liquid, the light oil has a large cetane number. Therefore, even if light oil is mixed into the combustion chamber, it can be burned with the fuel alcohol if the temperature rises. Thus, the generation of hydrocarbons in the exhaust gas can be suppressed, the adverse effect is reduced, and a sufficient lubrication function can be performed on the sliding surface.

〔Example〕

Hereinafter, an embodiment of a lubrication device for an alcohol engine according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view showing an embodiment of a lubricating device for an alcohol engine according to the present invention, and FIG. 2 is an enlarged sectional view of a portion A in FIG.

The alcohol engine incorporating the lubricating device according to the present invention shown in FIG. 1 uses alcohol as fuel. The alcohol engine of this embodiment is operated in two cycles. The cylinder head is fixed to the cylinder block 6 via a gasket, and an exhaust valve is arranged on the cylinder head. (Not shown), a two-cycle engine using the crankcase 12 as a compressor, and the scavenging action is performed by airflow in a certain direction with respect to the cylinder center line. , Which improves the efficiency of the engine. Further, in this embodiment, a two-cycle alcohol engine is described, but the lubricating device for an alcohol engine according to the present invention is also applicable to a four-cycle alcohol engine.

In this alcohol engine, a cylinder liner 4 is fitted to a cylinder 23 formed in the cylinder block 6. The combustion chamber 8 is a chamber formed by the lower surface of the cylinder head, the cylinder liner 4 and the piston head 34 of the piston 7. The combustion chamber 8 can be configured to have a heat insulating structure by manufacturing the lower surface of the cylinder head, the cylinder liner 4 and the piston head 34 from a ceramic material. Since the cylinder liner 4 is a part that provides a sliding surface 28 on which the piston 7 reciprocates, the cylinder liner 4 is made of zirconia (Zr
O ₂ ) or a ceramic material such as silicon carbide (SiC). In particular, as shown in FIG. 2, a coating layer 11 made of a solid lubricant such as CaF is formed. The crankcase 12 is formed by a crankcase 16 below the cylinder block 6.

The piston 7, which reciprocates in the cylinder or the cylinder liner 4, is constituted by a piston head 34 and a piston skirt 36. The entire piston 7 can be made of aluminum material. Alternatively, the piston skirt 36 is made of aluminum, and the piston head 34 is made of zirconia, aluminum titanate (Al).
A heat insulating structure can be formed by using a heat insulating material such as ₂ TiO ₅ ) or a ceramic material. By manufacturing the piston 7 from an aluminum material, the sliding surface 41 of the piston 7 opposing the cylinder liner 4 is made into Al ₂ O ₃ , and metal contact with the cylinder liner 4 can be avoided. The piston ring 10 is fitted in the piston ring groove 35 of the piston 7. As shown in FIG. 2, the piston ring 10
Like the cylinder liner 4, it is a sliding part, and therefore, like the cylinder liner 4, is preferably made of a ceramic material such as zirconia, silicon carbide, silicon nitride (Si ₃ N ₄ ), or a composite material. In particular, in the piston ring 10, a coating layer 11 made of a solid lubricant such as CaF is formed on a sliding surface 21 with the cylinder liner 4.

In order to coat the sliding surface 28 of the cylinder liner 4 and the sliding surface 21 of the piston ring 10 with the coating layer 11 using a solid lubricant such as CaF, for example, a CaF
And a piston 11 is reciprocated to slide the piston ring 10 against the cylinder liner 4 to form a reaction film on the sliding surfaces 21 and 28. It is fixed to the sliding surfaces 21 and 28.

In the two-stroke alcohol engine, an intake passage 18 communicating with an intake port 20 formed in the cylinder liner 4 is provided below the cylinder block 6. Intake passage
In order to introduce the intake air into the intake passage 18, the intake passage 18
It communicates with a communication hole 37 formed in the crankcase 16 that constitutes 12. An intake passage 13 having a check valve 19 is connected to the crankcase 16, and the intake passage 13 is provided with an alcohol injector 40 for sucking alcohol fuel into the crank chamber 12 together with intake air. In some cases, the intake passage 13 can communicate with a compressor of a turbocharger. With the above configuration,
The alcohol fuel injected from the alcohol injector 40 into the intake passage 13 becomes a mixture with the intake air and is sucked into the crank chamber 12 through the check valve 19. The air-fuel mixture sucked into the crank chamber 12 is sucked into the combustion chamber 8 from the communication hole 37 of the crank case 16 through the intake passage 18 and the intake port 20 of the cylinder liner 4.

Further, the two-stroke alcohol engine has the following configuration in addition to the above configuration. In order to reciprocate the piston 7, a small diameter portion 29 of a connecting rod 25 is connected to the piston 7 so as to be rotatable and slidable. That is, a metal serving as a bearing made of an aluminum material which is resistant to moisture is incorporated between the piston pin 17 and the piston pin hole formed in the piston pin boss of the piston 7 (not shown). Is rotatably fitted to the small-diameter portion 29 via the metal 14. The large-diameter portion 24 of the connecting rod 25 is rotatably connected to the crankpin 19 of the crankshaft 38. The entire surface of the crankshaft 38 is plated with an Fc material. In a crankpin hole 27 formed in the large-diameter portion 24 of the connecting rod 25, a metal 15 serving as a bearing made of a water-resistant aluminum material is incorporated between the crankpin 39 and the crankpin hole 27. Further, since the crankshaft 38 is rotatably mounted on the bearing portion 30 of the cylinder block 6, the crankshaft 38
The 38 crank journals 26 are provided between the bearings 30 and the metal 15 which is a bearing made of moisture-resistant aluminum material.
Is incorporated.

The lubricating device of the alcohol engine is applied to sliding parts such as a sliding part between the cylinder liner 4 and the piston ring 10 or the piston skirt 36, a rotary sliding part where metal such as the crankshaft 38 and the connecting rod 25 is interposed. It is configured to supply light oil as lubricating oil to be supplied. A large number of through-holes 9 are formed in the peripheral direction of the lower part of the ceramic cylinder liner 4 so as to communicate with a sliding portion which is a sliding surface between the piston ring 10 and the piston skirt 36. These through holes 9 communicate with the light oil reservoir 2 formed in the lower peripheral direction of the cylinder block 6, and serve to supply the light oil supplied to the light oil reservoir 2 to the inner wall surface of the cylinder liner 4. The light oil supply pump 1 supplies light oil from a light oil tank to each sliding portion, and supplies light oil to a light oil reservoir 2 through a light oil passage 3. Further, the light oil supply pump 1
Light oil is supplied to the metal 15 of the crank journal 26 of the crankshaft 38 through the light oil passage 5. The light oil passage 32 is formed in the crankshaft 38, and the crank journal
The light oil supplied to 26 is supplied to the crankpin 39 through the light oil passage 32. The light oil supplied to the crank pin 39 is supplied to the metal 15 between the large diameter portion 24 of the connecting rod 25 through the light oil passage 33. Further, the light oil supplied to the light oil passage 32 of the crankshaft 38 is supplied to the metal 14 between the small diameter portion 29 of the connecting rod 25 and the piston pin 17 through the light oil passage 31 formed in the connecting rod 25.

〔The invention's effect〕

The lubricating device for an alcohol engine according to the present invention is configured as described above, and has the following effects.
Since the lubricating device for an alcohol engine is configured as described above, when the engine is partially loaded, the sliding surfaces of the cylinder liner and the piston ring and the sliding portions of the crankshaft and the connecting rod are made of a lubricating fluid made of light oil. The fluid lubrication can be performed well. When the engine is under a high load, the temperature of the combustion chamber is high, and the coating layer of solid lubricant such as CaF formed on each sliding surface between the piston ring and the cylinder liner is formed by boundary lubrication. The friction coefficient at the time can be reduced, and good lubrication can be achieved to prevent adhesion. By forming the coating layer of a solid lubricant such as CaF on each of the sliding surfaces, the coating layer has a friction coefficient of 0.1 or less at a high temperature and has a lubricating function on a high-temperature surface where light oil supplied as a lubricating liquid is lost. Can work well.

Furthermore, if light oil is used as the lubricating liquid, the light oil has a high cetane number, so even if light oil is mixed into the combustion chamber, the light oil can be burned together with the fuel alcohol by increasing the temperature of the combustion chamber. Compared with the case where a lubricating oil is used, the generation of hydrocarbons in the exhaust gas can be greatly suppressed, the adverse effect is reduced, and a sufficient lubricating function can be achieved.

When the piston skirt is made of aluminum, the outer peripheral surface of the piston skirt, which is a sliding surface with respect to the cylinder liner, is made of Al ₂ O ₃ so that it comes into metallic contact with the cylinder liner. Can be avoided, and a desirable state can be provided for the sliding surface.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view for explaining an embodiment of a lubricating device for an alcohol engine according to the present invention, and FIG. 2 is an enlarged sectional view of a portion A in FIG. 1 ... light oil supply pump (pump), 3,5,31,32,33 ... light oil passage (lubricating liquid passage), 4 ... cylinder liner, 7 ... piston, 8 ... combustion chamber, 9 ... through Hole, 10 ... piston ring, 11
…… Coating layer of solid lubricant, 12 …… Crankcase, 14,15 ……
Metal (sliding part), 21, 28 ... sliding surface, 25 ... connecting rod,
38 ... Crankshaft.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01M 1/06 F01M 9/04 F01M 9/12 F02F 1/00

Claims (2)

(57) [Claims] 1. A coating layer of a solid lubricant formed on each sliding surface of a ceramic piston ring and a ceramic cylinder liner, and a cylinder liner opening on the sliding surface for supplying a lubricating liquid to the sliding surface. A lubricating fluid passage communicating with a number of through holes formed in a lower peripheral direction, a lubricating fluid passage for supplying the lubricating fluid to a sliding portion between a crankshaft and a connecting rod, and a pump for supplying the lubricating fluid to each of the lubricating fluid passages A lubricating device for an alcohol engine, comprising: using alcohol as a fuel and using light oil as the lubricating liquid supplied by the pump. 2. The accumulator engine lubrication system according to claim 1, wherein CaF is used as said solid lubricant constituting said coating layer.