JPH0868322A - Piston cooling device for internal combustion engine - Google Patents

Abstract

PURPOSE: To efficiently cool a piston while applying oil to the whole back surface of a piston, reduce a manufacturing cost, improve assembling performance, and surely recover the oil used for cooling. CONSTITUTION: A recession 38 is opened at a split surface on one side of a crank case 2. Oil is press-fed through an oil supply passage 39 communicated with the recession 38. An injection nozzle 41 is fitted to the recession 38 and operated for injecting the oil from the oil supply passage 39 to a rear surface of the piston D of the injection nozzle 41 on the rear side of the piston back surface in respect to a rotational direction of a crank shaft. A pressurizing part 37 is provided on the other split surface of the crank case 2 for holding the injection nozzle 41 inside the recession at the mating time of the crank case 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston cooling device for an internal combustion engine, which cools the piston by injecting oil on the back surface of the piston.

[0002]

2. Description of the Related Art Conventionally, piston cooling devices of this type are
A crankcase that guides oil to a crank journal that supports the crankshaft of an internal combustion engine and injects the oil from an oil injection hole provided on the upper part (piston side) of the crank journal toward the back surface of the piston, or a crankcase. There was a thing in which an injection nozzle for injecting oil was screwed to the inner wall of the.

[0003]

However, in the former case, since the oil injection hole is offset with respect to the center of the piston, the injected oil is blocked by the crankshaft web, connecting rod, piston pin, etc. The entire back surface was not hit, and the piston could not be cooled efficiently.

In the latter case, the manufacturing cost of the internal combustion engine increases because it is necessary to form a pedestal and a screw hole for screwing the injection nozzle on the inner wall of the crankcase, and to prevent the screw from loosening. In addition, since the assembly work of aligning the injection nozzle and fixing it with a screw is separately required, there is a drawback that the assemblability of the internal combustion engine deteriorates.

By the way, when oil is injected toward the back surface of the piston, when the oil hits the back surface of the piston drops downward, it is hit by the rotating crankshaft and atomized, and diffused in the crankcase. Therefore, there is a concern that oil may leak to the outside from the breather hole that adjusts the atmospheric pressure in the crankcase.

The present invention has been made in order to solve such a problem. Oil is applied to the entire back surface of the piston to cool the piston efficiently, and the manufacturing cost is low and the assemblability is good. An object of the present invention is to provide a piston cooling device for an internal combustion engine, which can surely recover the oil used for cooling.

[0007]

In order to achieve the above object, in a piston cooling device for an internal combustion engine according to the present invention, a crankcase passes through a cylinder bore central axis of a cylinder assembly and is orthogonal to the axial direction of the crankshaft. In a split internal combustion engine, a recess opening on one split surface of the crankcase, an oil supply passage through which oil is pumped through the recess, and an oil from the oil supply passage fitted in the recess Is provided on the split surface on the other side of the crankcase, and an injection nozzle that injects oil onto the back surface of the piston, positioning means that determines the oil injection position of the injection nozzle toward the rear of the piston back surface with respect to the rotation direction of the crankshaft. And a pressing portion for holding the injection nozzle in the concave portion when the crankcases are aligned with each other. .

[0008]

According to the piston cooling device for an internal combustion engine having the above-described structure, the oil pressure-fed to the recess from the oil supply passage is injected from the injection nozzle to the back surface of the piston to cool the piston.

Since the injection nozzle is provided along the split surface of the crankcase, that is, along the central axis of the cylinder bore, the oil injected from the injection nozzle is not blocked by the crankshaft web, connecting rod, piston pin, etc. It hits the entire surface and cools the piston efficiently.

Further, since the recess and the oil supply passage can be simultaneously drilled in the crankcase when drilling another hole in the crankcase, the manufacturing cost of the internal combustion engine does not increase. Moreover, in order to assemble the piston cooling device, the injection nozzle is simply fitted into the recess when the crankcases are aligned, and the oil injection direction of the injection nozzle is determined by the positioning means at that time. It does not decrease.

Further, since the oil is injected toward the rear of the rear surface of the piston with respect to the rotational direction of the crankshaft, the oil that strikes the rear surface of the piston and drops downward quickly joins the airflow generated along the rotational direction of the crankshaft. And fall to the bottom of the crankcase. For this reason, the oil is reliably recovered.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view showing an example of an internal combustion engine to which a piston cooling device according to the present invention is applied.

The internal combustion engine 1 is of a four-cycle single cylinder used in, for example, a motorcycle, and a cylinder assembly 3 is provided on the upper portion of a crankcase 2 of the cylinder assembly 3 while tilting forward. The cylinder assembly 3 has a structure in which a cylinder block 4, a cylinder head 5, and a head cover 6 are fixed on a crankcase 2 in order.

A cylindrical cylinder bore 7 is formed in the cylinder block 4, and a combustion chamber 8 aligned with the cylinder bore 7, an intake port 9 and an exhaust port 10 communicating therewith are formed in the cylinder head. An intake valve 11 and an exhaust valve 12 for opening and closing the intake port 9 and the exhaust port 10 are provided in the cylinder head 5, and a valve operating device 13 for driving the intake and exhaust valves 11 and 12 is built in. There is. An exhaust pipe 14 is connected to the exhaust port 10.

A crankshaft 16 is rotatably supported in the crankcase 2. The crankshaft 16 rotates counterclockwise in FIG. On the other hand, a piston 17 is slidably inserted into the cylinder bore 7, and a piston pin 18 provided on the piston 17 and a crank pin 20 eccentrically mounted on a web 19 of the crankshaft 16 are connected by a connecting rod 21. Be connected. Therefore, the reciprocating motion of the piston 17 is converted into the rotary motion of the crankshaft 16.

Further, in front of the crankshaft 16 (left side in the figure)
A balancer shaft 23 is rotatably supported by the gearbox 24, and a transmission 24 is installed behind the crankshaft 16 (on the right side in the drawing). These devices are lubricated by the oil 25 injected into the bottom of the crankcase 2.

A breather hole 26 for adjusting the atmospheric pressure in the crankcase 2 is provided in the upper portion of the crankcase 2, and a breather chamber for separating the air and the oil component so that the oil 25 does not blow out from the breather hole 26. And a starter motor 28 is installed above the breather chamber 27.

FIG. 2 is a top view of the crankcase 2 taken along the line II-II of FIG. This crankcase 2
It has a structure in which it is divided into left and right at a plane B that passes through the central axis A of the cylinder bore 7 and is orthogonal to the axial direction of the crankshaft 16. Note that FIG. 1 shows a state in which the left half of the crankcase 2 is removed and only the right half is left.

A flat cylinder mating surface 29 is formed on the upper surface of the crankcase 2, and the lower surface of the cylinder bore 7 is closely fixed to the cylinder mating surface 29. At that time, the sleeve 32 of the cylinder bore 7 is inserted into the circular sleeve insertion opening 31 provided on the cylinder mating surface 29, and
A cam chain (not shown) is inserted through a square cam chain opening 33 provided adjacent to 31. The alternate long and short dash line C drawn in FIG. 2 indicates the back surface profile of the piston 17.

The crankcase 2 is provided with a piston cooling device 34 according to the present invention. The piston cooling device 34 is a device that cools the piston 17 by injecting oil onto the back surface of the piston 17, and is configured as follows.

First, a front wall 35 of the breather chamber 27 is located rearward of a lower portion of the sleeve insertion port 31.
On the right half side of 35, for example, a cylindrical thick portion 36 is formed parallel to the axial direction of the crankshaft 16 (see also FIG. 3). On the other hand, on the left half side of the front wall 35, a pressing portion 37 that comes into contact with the end surface of the thick portion 36 is provided.

A cylindrical hole-shaped recess is formed in the thick portion 36.
38 is formed. The recess 38 opens on the right division surface of the crankcase 2. Further, an oil supply passage 39 communicating with the recess 38 is formed coaxially with the recess 38. An oil pipe 40 is externally provided in the oil supply passage 39.
Is connected, and the other end of the oil pipe 40 is connected to an oil pump (not shown). Therefore, the oil discharged from the oil pump (oil 25 injected into the bottom of the crankcase 2) is pressure-fed to the oil supply passage 39 via the oil pipe 40.

Further, an injection nozzle 41 is fitted in the recess 38. The injection nozzle 41 has, for example, a cylindrical nozzle base portion 42 that is closely fitted to the recess 38, and a pipe-shaped nozzle tube 43 that extends from the nozzle base portion 42, and the nozzle base portion 42 has an internal passage. 44 is formed coaxially, and the inner diameter of the nozzle tube 43 communicates with the internal passage 44. The nozzle tube 43 extends in the radial direction of the nozzle base portion 42 and is bent or curved in the middle, and the inner diameter of the tip end portion thereof is narrowed to reduce the oil injection hole.
45 are formed.

When the nozzle base portion 42 is fitted in the recess 38, the internal passage 44 of the nozzle base portion 42 and the oil supply passage 39 communicate with each other. An O-ring is provided between the recess 38 and the nozzle base 42.
46 is interposed, and the oil supply passage 39 and the internal passage 44 are liquid-tightly sealed. When the left and right crankcases 2 are fitted together, the pressing portion 37 contacts the end surface of the thick portion 36 and simultaneously contacts the end surface 47 of the nozzle base portion 42, so that the injection nozzle 41 is held in the recess 38.

As shown in FIGS. 2 and 3, a cutout 50 is formed in the peripheral wall of the recess 38. This notch 50 serves as a positioning means for determining the oil injection direction of the injection nozzle 41, and if the nozzle tube 43 is fitted into the notch 50 when the nozzle base portion 42 of the injection nozzle 41 is fitted in the recess 38. The position of oil injection from the nozzle pipe 43 is determined in the rearward portion D of the piston 17 with respect to the rotation direction of the crankshaft 16.

The piston cooling device 34 is constructed as described above. Next, the operation of the piston cooling device 34 will be described.

The oil pressure-fed to the oil supply passage 39 by the oil pump passes through the inner passage 44 of the nozzle base 42 and the nozzle pipe 43, and is jetted from the oil injection hole 45 at the tip of the nozzle pipe 43 to the back surface of the piston 17 to Cool 17 Here, since the injection nozzle 41 is provided along the split surface of the crankcase 2, that is, along the central axis A of the cylinder bore 7, the oil injected from the injection nozzle 41 is
16 web 19 and connecting rod 21, piston pin 18 etc. hit the entire back surface of piston 17
Cool 17 efficiently.

Further, since the oil injection position D to the rear surface of the piston 17 is set to the rearward portion with respect to the rotation direction of the crankshaft 16, the oil that hits the rear surface of the piston 17 and falls downward is indicated by the arrow E. As shown by (3), the airflow F generated along the rotation direction of the crankshaft 16 quickly joins and falls to the bottom of the crankcase 2. Therefore, the oil does not hit the crankshaft 16 and is not atomized, the oil is prevented from leaking from the breather hole 26, and the oil is reliably collected. The alternate long and short dash line G indicates the bottom dead center position of the piston 17.

This piston cooling device 34 includes an injection nozzle 41
Since the recess 38 into which is fitted and the oil supply passage 39 can be simultaneously machined when drilling another hole of the crankcase 2, the manufacturing cost of the internal combustion engine 1 does not increase.

Moreover, in order to assemble the piston cooling device 34, the injection nozzle 41 is simply fitted into the recess 38 when the crankcase 2 is aligned, and at that time, the nozzle pipe 43 is fitted into the notch 50 serving as the positioning means. For example, since the oil injection direction is easily determined, the assemblability of the internal combustion engine 1 does not deteriorate.

The piston cooling device 34 according to the present invention
Can be applied not only to an internal combustion engine for a motorcycle but also to an internal combustion engine of an automobile, a ship or the like. Further, even in an internal combustion engine of the type in which the crankcase is divided along the axial direction of the crankshaft, the same injection nozzles as in the present embodiment are provided on the division surface of the crankcase, and the nozzle pipe is directed toward the cylinder bore side. Various operational effects can be obtained.

[0032]

As described above, in the piston cooling device for an internal combustion engine according to the present invention, the crankcase is divided by the plane orthogonal to the axial direction of the crankshaft through the center axis of the cylinder bore of the cylinder assembly. At
A recess opening on one split surface of the crankcase,
An oil supply passage through which oil is pumped through the recess, an injection nozzle that is fitted into the recess and injects the oil from the oil supply passage to the back surface of the piston, and an oil injection position of the injection nozzle is set to the crankshaft. Positioning means that is defined on the rear side of the piston rearward with respect to the rotation direction of
It is characterized in that it is provided with a pressing portion which is provided on the other split surface on the other side of the crankcase and which holds the injection nozzle in the recess when the crankcase is aligned.

According to this structure, since the injection nozzle is provided along the split surface of the crankcase, that is, along the center axis of the cylinder bore, the oil injected from the injection nozzle is applied to the crankshaft web, connecting rod, piston pin, and the like. The piston can be efficiently cooled by hitting the entire back surface of the piston without being blocked.

Further, since the recess and the oil supply passage can be simultaneously machined in the crankcase when the other holes of the crankcase are drilled, the manufacturing cost of the internal combustion engine is not increased, and moreover, the piston cooling device can be assembled by using the crankcase. The injection nozzle is simply fitted into the recess when the cases are aligned, and the oil injection direction of the injection nozzle is determined by the positioning means at that time, so the assemblability of the internal combustion engine does not deteriorate.

Furthermore, since the oil is injected toward the rear of the rear surface of the piston with respect to the rotation direction of the crankshaft, the oil that strikes the rear surface of the piston and drops downward quickly joins the airflow generated along the rotation direction of the crankshaft. And fall to the bottom of the crankcase. For this reason, the oil is less likely to be atomized, and the oil is reliably collected.

[Brief description of drawings]

FIG. 1 is a left side view showing an example of an internal combustion engine to which a piston cooling device according to the present invention is applied.

FIG. 2 shows an embodiment of the present invention and is taken along line II-II of FIG.
The top view of the crankcase by the arrow view.

FIG. 3 is an exploded perspective view of a piston cooling device.

[Explanation of symbols]

 1 Internal Combustion Engine 2 Crankcase 3 Cylinder Assembly 4 Cylinder Block 7 Cylinder Bore 16 Crank Shaft 17 Piston 21 Connecting Rod 25 Oil 29 Cylinder Mating Surface 34 Piston Cooling Device 37 Pressing Part 38 Recess 39 Oil Supply Passage 41 Injection Nozzle 42 Nozzle Base 43 Nozzle Pipe 44 Internal passage 45 Oil injection hole 46 O-ring 50 Notch as positioning means A Cylinder bore central axis B Crankcase dividing surface C Piston back surface profile D Oil injection position on piston back surface

Claims (1)

[Claims] 1. An internal combustion engine in which a crankcase is divided by a plane that passes through a cylinder bore center axis of a cylinder assembly and is orthogonal to the axial direction of the crankshaft, and a concave portion that opens on one division surface of the crankcase and the concave portion. Oil supply passage through which oil is pumped, the injection nozzle that is fitted in the recess and injects the oil from the oil supply passage to the back surface of the piston, and the oil injection position of the injection nozzle is the rotation of the crankshaft. The positioning means is defined on the rear side of the piston rearward with respect to the direction, and the pressing portion is provided on the other split surface on the other side of the crankcase and holds the injection nozzle in the recess when the crankcase is aligned. A piston cooling device for an internal combustion engine, which is characterized in that: