JPS584163B2 - Piston reciprocating internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a reciprocating piston type internal combustion engine, such as a gasoline engine or a diesel engine, which extracts power by converting reciprocating motion of a piston into rotational motion.

In the above-mentioned reciprocating piston internal combustion engine, a predetermined piston clearance is usually provided between the piston and the cylinder wall.

In particular, pistons using aluminum alloy pistons undergo large thermal expansion, so it is necessary to increase the piston clearance.For this reason, in this type of internal combustion engine, during engine operation, the piston clearance When the piston changes its direction of motion, the cylinder wall is struck by the tilt of the piston, producing a hitting sound (piston slap).

The present invention was made for the purpose of reducing the noise caused by such piston slap, and in particular, it is possible to accurately reduce the noise, and at the same time, it is possible to reduce wear on the piston and cylinder and improve their durability. Furthermore, it is an object of the present invention to provide a reciprocating piston internal combustion engine that is improved so that the piston cooling effect can be enhanced.

For this purpose, the present invention provides an oil inlet that communicates with a lubricating oil reservoir through an oil feed pump in the inner surface of the cylinder wall in the piston reciprocating internal combustion engine as described above. The inlet is located outside the piston ring sliding range in the piston sliding direction, facing the outer peripheral surface of the piston skirt part from the bottom dead center position to a predetermined upward stroke, and facing the piston pin axis in the circumferential direction of the cylinder wall. A pair of oil guide grooves are provided on the outer circumferential surface of the skirt portion of the piston facing the pair of oil inlets, each extending along the piston sliding direction. It is characterized by the fact that it has been provided.

Incidentally, as an example of related prior art, Japanese Unexamined Patent Application Publication No. 48-21
As described in Japanese Patent No. 014, there is a piston skirt having a plurality of oil guide grooves extending in the axial direction on the peripheral surface of the skirt. It is characterized by the fact that it is arranged so as to face the oil inlet provided on the inner surface of the cylinder wall, so that oil can be forcibly filled between the piston and the cylinder wall even when the piston is at the top dead center position. have

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

1 to 3 show an embodiment in which the present invention is applied to a diesel engine, in which 1 is a cylinder block, 2 is a cylinder head, and 3 is a cylinder, in which a piston 4 slides. It is inserted so that it can move freely.

Further, a combustion chamber 7 equipped with an intake/exhaust valve 5 and a fuel injection nozzle 6 is formed in the upper part of the cylinder 3, and the piston 4 has a gas ring 8a and an oil ring 8b on its top peripheral surface. A piston ring 8 is fitted into the cylinder 3 so that the piston 4 can reciprocate and slide inside the cylinder 3 while maintaining airtightness. ), and the configuration and functions described above are the same as the conventional ones.

In the present invention, an oil inlet 10 is opened on the inner surface of the cylinder 3 in which the piston 4 reciprocates.

The oil inlet 10 is opened at a location facing the circumferential surface of the piston skirt portion 4a at the bottom dead center position outside the sliding range of the piston ring 8 with respect to the sliding direction of the piston 4, and the oil is jetted from the inlet 10. Oil is gas ring 8a
Alternatively, the oil ring 8b may be provided at a position where it will not be dragged into the combustion chamber 7 side.

In particular, the oil inlet 10 is opened at the upper part of the skirt portion 4a of the piston 4 at the bottom dead center position, that is, at a position close to the oil ring 8b, and when the piston 4 is on a predetermined upward stroke. is arranged to face the skirt portion 4a.

The oil inlet 10 is communicated with an annular oil groove 12 provided in the joint surface between the cylinder block 1 and the crankcase 11, and the oil groove 12 is connected to the oil pump via an oil passage 13 indicated by a dotted line. It is connected to the oil discharge side of No. 15.

The oil pump 15 includes a plunger 17 that is slidably inserted in a pump chamber 16 formed in the upper part of the crankcase 11 in the axial direction thereof, and a pump that urges the plunger 17 in one direction. The end face of the plunger 17, which is made up of a coil spring 18 etc. housed in the chamber 16 and which is biased by the coil spring 18 and protrudes outside the pump chamber 16, is
It is pressed into contact with a pump driving force ram 20 provided on a camshaft 19 that interlocks with a crankshaft (not shown).

Also, check valves 22 (the suction side is not shown) that receive back pressure from a spring 21 are provided on the suction side and the discharge side of the oil pump 15, respectively. Crankcase 1 through 24
It communicates with an oil reservoir 25 provided at the bottom of 1.

Here, the oil inlets 10 are opened in pairs on the left and right sides in FIG. 1 so as to be located on both sides perpendicular to the axial direction of the piston pin with respect to the circumferential direction of the inner surface of the cylinder wall.

According to the present invention, in particular, one oil guide groove 14 extending along the sliding direction of the piston is provided on the outer circumferential surface of the piston skirt portion 4a at locations facing the oil inlets 10, 10. ing.

With this configuration, when the engine is operated, the plunger 17 rotates as the pump drive cam 20 rotates in conjunction with the rotation of the camshaft 19 that is linked to the crankshaft (not shown).
is reciprocated within the pump chamber 16 by the action of the convex portion 20a of the cam 20 and the coil spring 18, and the oil pump 15 operates to discharge lubricating oil from the oil inlet 10 via the oil path 13 and the oil groove 12. Injected into cylinder 3.

At the bottom dead center of the piston 4, this lubricating oil is injected toward the oil guide groove 14 provided opposite the oil inlet 10, filling the oil guide groove 14, and filling the skirt portion 4a of the piston 4. Figure 3 shows a relatively thick high-pressure oil film that is forced into the piston clearance by the injected lubricating oil. Since this oil film is formed over the forced hydraulic action range A shown in FIG.

Therefore, the sound of the piston 4 hitting the inner wall of the cylinder 3 is reduced, and the noise caused by piston slap is reduced.

In this case, the oil inlet 10 is provided on the inner surface of the cylinder 3 at a location facing the piston skirt portion 4a at the bottom dead center position outside the sliding range of the piston ring 8 with respect to the sliding direction of the piston 4 as described above. Therefore, there is no fear that the lubricating oil injected from the injection port 10 will directly enter the combustion chamber 7 side or be dragged in by the gas ring 8a or the oil ring 8b.

Next, while the piston 4 is rising toward the top dead center position, since the oil guide groove 14 is provided so as to extend parallel to the sliding direction of the piston 4, the oil inlet 10 and The oil guide groove 14 maintains an opposing positional relationship.

During this time, that is, while the piston 4 is moving to a position near the top dead center, the lubricating oil injected from the oil inlet 10 by the oil feeding action from the lubricating oil supply source is introduced into the oil guide groove 14 and there. From the skirt portion 4a of the piston 4
The lubricating oil is forcibly lubricated into the gap (piston clearance) between the piston 4 and the inner wall surface of the cylinder 3, and this lubricating oil causes oil to flow inside the piston clearance, especially on the side near the piston land of the piston 4 at the top dead center position. A relatively thick high-pressure oil film is formed.

As a result, even at the top dead center position, the inclination of the piston 4 when changing its direction of motion is restricted, so that the sound of the piston 4 hitting the inner wall of the cylinder 3 is reliably reduced.

Thus, according to the present invention, the lubricating oil jetted out from the oil inlet by the oil feeding action of the oil pump is introduced into the oil guide groove in a concentrated manner without waste, and the oil guide groove faces each oil inlet. As a result, a relatively thick high-pressure oil film is formed near the oil guide groove, and this thick high-pressure oil film is perpendicular to the axial direction of the piston pin. Since it is formed within the piston clearances on both sides of the piston and from the bottom dead center position of the piston to a predetermined upward stroke, the direction of reciprocating movement of the piston is determined not only at the bottom dead center position of the piston but also at its top dead center position. The tilting movement of the piston when changing the position is restricted, and therefore the noise caused by piston slap can be accurately reduced.

In addition, a large amount of lubricating oil is injected between the piston and the inner wall of the cylinder, reducing wear on the piston and cylinder and improving their durability. Because it gets better,
Effects such as being able to enhance the cooling effect of the piston can also be obtained.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of essential parts of an internal combustion engine according to an embodiment of the present invention, FIG. 2 is a side view of the piston in FIG. 1, and FIG.
The figure is a partial sectional view showing an oil groove and an oil inlet in a cross section taken along the line A-A in FIG. 1... Cylinder block, 2... Cylinder head,
3... Cylinder, 4... Piston, 4a... Piston skirt portion, 5... Intake/exhaust valve, 6... Fuel injection nozzle 7... Combustion chamber, 8... Piston ring, 8
a...Gas ring, 8b...Oil ring, 9...
・Conn rod, 10... Oil inlet, 11... Crank case, 12... Oil back, 13... Oil path, 14
...Oil guide groove, 15...Oil pump, 16.
... Pump chamber, 17... Plunger, 18... Coil spring, 19... Camshaft, 20... Pump drive cam, 20a... Convex portion, 21... Spring, 22...
... Check valve, 23 ... Suction pipe, 24 ... Oil strainer, 25 ... Oil reservoir, A ... Forced hydraulic action range.

Claims (1)

[Claims] 1. In an internal combustion engine in which a piston is inserted into a cylinder and the reciprocating motion of the piston is converted into rotational motion, an oil inlet is opened on the inner surface of the cylinder wall to communicate with a lubricating oil reservoir via an oil feed pump. However, this oil inlet is located outside the piston ring sliding range in the piston sliding direction, facing the outer circumferential surface of the skirt portion of the piston from the bottom dead center position to a predetermined upward stroke, and in the circumferential direction of the cylinder wall. are provided in pairs so as to be located on both sides perpendicular to the axial direction of the piston pin, and oil guide grooves extending along the piston sliding direction are provided on the outer peripheral surface of the skirt portion of the piston facing the pair of oil inlets. A piston reciprocating internal combustion engine characterized by having one thread for each.