JPH0151650B2 - - Google Patents

Abstract

PURPOSE:To provide the smooth returning of lubricant oil in a crankchamber to an oil pan by a method wherein the passage area of pressure communicating passage is made large and the balance of pressure between the crankchamber and the cam chamber is kept under a good condition and the splashing of the lubricant oil from the crankchamber to the pressure communicating passage is prevented. CONSTITUTION:A cylinder case 20 and a cylinder head 22 are formed with a pressure communicating passage 66 for communicating a crankchamber 28 with a cam chamber 35. The pressure communicating passage 66 is extended substantially in a non-tangential direction of the rotation of a crankshaft 29 with its opening at the crankchamber 28 being not oppositely faced substantially to the tangential direction of the rotation of the crankshaft 29. Therefore, even if the passage area of the pressure communicating passage 66 is of a large value, the lubricant oil rotated in the rotating direction of the crankshaft 29 is prevented to flow by the inner surfaces of the cylinder case 20 and the crankcase 21 without having an opening of the pressure communicating passage 66 in its rotating direction, and so it may not be flashed directly into the pressure communicating passage 66.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a four-stroke internal combustion engine.

[Conventional technology]

In a four-cycle internal combustion engine, as shown in FIG. 1, a crank chamber 1 and a cam chamber 2 are communicated through a pressure communication passage 3, and blow-by gas entering the crank chamber 1 is introduced into the cam chamber 2. Furthermore, it can be discharged to the carburetor side via the breather 4, and
The pressure balance between the crank chamber 1 and the cam chamber 2 is maintained well, and lubricating oil can be smoothly returned from the cam chamber 2 to the oil pan.

[Problem to be solved by the invention]

However, in conventional four-stroke internal combustion engines in which the crankshaft is vertically placed, especially in outboard motors, the passage area of the pressure communication passage 3 is increased to maintain a good pressure balance between the crank chamber 1 and the cam chamber 2. Then, the crankshaft 5 placed vertically
As the lubricating oil rotates, the lubricating oil tends to flow from the crank chamber 1 through the pressure communication path 3 into the cam chamber 2 as shown by the arrow in Figure 1, and the lubricating oil does not return to the oil pan quickly. This may cause the oil temperature to rise excessively and cause premature deterioration, or it may be necessary to increase the capacity of the oil pan in order to ensure a sufficient amount of circulating oil.

In a four-stroke internal combustion engine with a vertically placed crankshaft, the present invention maintains the pressure balance between the two chambers by allowing air and blow-through gas to freely flow through a pressure communication passage provided between the crank chamber and the cam chamber. The purpose is to reliably prevent lubricating oil from entering the pressure communication path while maintaining its original function of maintaining good pressure.

[Means to solve the problem]

The present invention provides a return oil passage between an oil pan and a crank chamber in which a crankshaft is housed vertically, a cam chamber in which a camshaft is housed, and an oil pan between the crank chamber and the cam chamber. In a four-cycle internal combustion engine in which the pressure communication passages communicate with each other through a pressure communication passage, the crank chamber side opening of the pressure communication passage is provided above the oil level of the lubricating oil in the crank chamber, and the cam chamber side opening of the pressure communication passage is provided above the oil level of the lubricating oil in the crank chamber. Provided above the oil level of the lubricating oil, and with the engine facing the cylinder head above the crankshaft and viewed from the axial direction of the crankshaft, the pressure communication passage is connected to the crankshaft with the plane passing through the cylinder center axis as the boundary. It is provided on the side of the cylinder case on the side in the same direction as the rotational direction of the crankshaft in the cylinder side half of the axial cross section.

[Effect]

According to the present invention, there are the following effects.

In a four-stroke internal combustion engine in which the crankshaft is arranged vertically, the opening on the crank chamber side of the pressure communication passage is provided above the lubricating oil level in the crank chamber, and the opening on the cam chamber side of the pressure communication passage is provided on the cam chamber side. Since the lubricating oil is provided above the lubricating oil level, the lubricating oil that circulates at a constant oil level in the crank chamber and cam chamber does not enter the pressure communication path.

``With the engine facing upward from the crankshaft to the cylinder head and viewed from the axial direction of the crankshaft, the pressure communication passage is connected to the cylinder side half of the cross section of the crankshaft, with the plane passing through the cylinder center axis as the boundary. Since the pressure communication passage is provided on the side of the cylinder case in the same direction as the rotational direction of the crankshaft, the pressure communication passage does not open into the inner surface of the crankshaft chamber facing substantially tangentially to the rotation of the crankshaft. For this reason,
The lubricating oil that travels in the direction of rotation of the crankshaft is blocked by the wall surface of the crankcase because there is no opening of the pressure communication path in the direction of movement of the lubricating oil, which prevents the lubricating oil from entering the pressure communication path. I'm never invited.

According to the above, in a four-stroke internal combustion engine in which the crankshaft is vertically placed, in the pressure communication passage provided between the crank chamber and the cam chamber,
It is possible to reliably prevent lubricating oil from entering the pressure communication path while maintaining the original function of maintaining a good pressure balance between the two chambers by allowing air and blow-by gas to flow freely.

〔Example〕

FIG. 2 is a side view showing an outboard motor to which an internal combustion engine according to an embodiment of the present invention is applied, FIG. 3 is a sectional view showing main parts of the internal combustion engine, and FIG. FIG. 5 is a sectional view taken along the line ``-'' in FIG. 4, and FIG. 6 is a sectional view taken along the line ``-'' in FIG. 3.

A clamp bracket 1 is attached to the stern plate 11 of the hull.
2. A casing 14 is supported via a swivel bracket 13. An internal combustion engine 16 is connected to the upper part of the casing 14 via a plate-shaped intermediate member 15.
is installed. The output of the internal combustion engine 16 is transmitted to the propeller 19 via a drive shaft 17 vertically disposed within the casing 14 and a forward/reverse switching mechanism 18, allowing the propeller 19 to rotate forward or backward.

As shown in FIGS. 3 and 4, the internal combustion engine 16 is a water-cooled four-stroke two-cylinder internal combustion engine,
A cylinder case 20, a crank case 21, a cylinder head 22, and a head cover 23 form the outer shell. A pair of upper and lower cylinders are placed horizontally in the cylinder case 20, and a piston 24 is arranged in each cylinder so as to be able to reciprocate in the horizontal direction.

A space defined by the cylinder case 20 and the cylinder head 22 on the top surface side of the piston 24 is a combustion chamber 25. A portion of the cylinder head 22 facing the combustion chamber 25 includes an ignition plug, an intake port opened by an intake valve 26, and an exhaust valve 27.
An exhaust port is provided which is opened by the valve. Further, a space defined by the cylinder case 20 and the crank case 21 on the back side of the piston 24 is defined as a crank chamber 28 . A crankshaft 29 is vertically disposed in the crank chamber 28 and is supported by a bearing formed at the mating surface of the cylinder case 20 and the crankcase 21.
The upper end of the drive shaft 17 is connected to the lower end of the drive shaft 17 . The crankshaft 29 has a crank pin 31 between its webs 30, and a large end 33 of a connecting rod 32 is connected to the crank pin 31. The small end of the connecting rod 32 is connected to the piston 24 by a piston pin 34. That is, the crankshaft 29 rotates according to the reciprocating motion of the piston 24 based on the explosive force within the combustion chamber 25, and
It is possible to apply rotational force to.

A space defined by the cylinder head 22 and head cover 23 is a cam chamber 35. A camshaft 36 is placed vertically in the cam chamber 35, and the camshaft 36
has its upper end directly supported by the cylinder head 22, and its lower end is connected to a lubricating oil pump 37, which will be described later.
cylinder head 22 through the housing 38 of
is indirectly supported. An intake cam 39 and an exhaust cam 40 are formed on the camshaft 36. The intake cam 39 and the exhaust cam 40 connect to the intake valve 26 and the exhaust valve 27 via rocker arms 42 supported by rocker shafts 41, respectively.
The valve can be opened. A driven wheel 43 is fixed to the upper end of the camshaft 36 that protrudes from the cam chamber 35, and a driving wheel 44 is fixed to the upper end of the crankshaft 29 that protrudes from the crank chamber 28. A belt 45 is wound around the drive wheel 44, and the camshaft 36 can be driven one rotation by one half rotation of the crankshaft 29.

As mentioned above, the housing 38 of the lubricating oil pump 37 is fixedly arranged on the lower surface of the cylinder head 22 coaxially with the camshaft 36. A pump chamber 46 is formed in the lubricating oil pump 37 , and an impeller 48 that is integrated with a connecting shaft 47 that hangs down from the lower end of the camshaft 36 is disposed in the pump chamber 46 . A suction passage 4 is provided at the bottom of the pump chamber 46.
9 is opened, and a discharge passage 5 is provided at the top thereof.
0 is open.

An oil pan 51 is suspended and fixed approximately at the center of the lower surface of the intermediate member 15. Above lubricating oil pump 3
The suction passage 49 of No. 7 lubricates the oil pan 51 through an oil passage 52 formed in the cylinder head 22 and the cylinder case 20, and a suction pipe 53 that communicates with the oil passage 52 and hangs vertically on the intermediate member 15. It is said that it is possible to communicate with oil. That is, the internal combustion engine 16
During operation, the lubricating oil pump 37 is driven together with the rotation of the camshaft 36, so that the lubricating oil in the oil pan 51 can be pumped to the discharge path 50 side.

The lubricating oil pumped by the lubricating oil pump 37 is sent from a discharge passage 50 to a lower oil passage 54 formed toward the crankshaft 29 on the lower surface side of the cylinder head 22 and cylinder case 20. At the same time, the crankshaft 29 is located on the upper surface side of the cylinder head 22 and cylinder case 20.
Oil is supplied to an upper oil passage 55 formed in a direction connecting the camshaft 36 and the camshaft 36. Note that the lower oil passage 54 and the upper oil passage 55 are communicated with each other by a connecting oil passage (not shown) that branches from the middle part of the lower oil passage 54 and extends vertically on the side surface of the cylinder case 20. There is.

The lubricating oil sent to the lower oil passage 54 is supplied to the bearing portion sealed by the oil seal 56 on the lower end side of the crankshaft 29, and lubricates the bearing portion as well as being drilled into the crankshaft 29. The crank pin 31 and the connecting rod 3 are connected to each other through the provided oil passage 58.
After lubricating the big end bearing part formed with the big end part 33 of No. 2, the lubricant is scattered into the crank chamber 28. Further, the lubricating oil flowing toward the crankshaft 29 side of the upper oil passage 55 is supplied to the bearing portion sealed by the oil seal 59 on the upper end side of the crankshaft 29, and lubricates the bearing portion and also lubricates the crankshaft 29 side. After lubricating the big end bearing formed by the crank pin 31 and the big end 33 of the connecting rod 32 through the oil passage 61 drilled in the oil passage 29, the oil is scattered into the crank chamber 28. The lubricating oil scattered within the crank chamber 28 as described above moves downward within the crank chamber 28 and enters the oil pan 51 via the return oil passage 62 formed by the cylinder case 20 and the intermediate member 15. It is starting to return to . Further, the lubricating oil flowing toward the camshaft 36 in the upper oil passage 55 lubricates the bearing portion sealed by the oil seal 63 on the upper end side of the camshaft 36, and then flows downward along the outer peripheral surface of the camshaft 36. and lubricates the cam surfaces of the intake cam 39 and exhaust cam 40. After lubricating the camshaft 36, the lubricating oil moves downward within the cam chamber 35 and returns to the oil pan 51 via a return oil passage 65 formed in the cylinder case 20 and cylinder head 22. There is.

Here, the cylinder case 20 and the cylinder head 22 include a crank chamber 28 and a cam chamber 35.
A pressure communication path 66 is formed to communicate with the.
The pressure communication passage 66 has an opening on the crank chamber 28 side above the lubricating oil level in the crank chamber 28, and an opening on the cam chamber 35 side above the lubricating oil level in the cam chamber 35. Further, when the engine is viewed from the crankshaft 29 with the cylinder head 22 above and from the axial direction of the crankshaft 29, the pressure communication passage 66 is connected to the cross section of the crankshaft 29 with the plane passing through the cylinder center axis as the boundary. It is provided on the side of the cylinder case 20 in the same direction as the rotational direction of the crankshaft 29 in the cylinder side half. The pressure communication passage 66 alleviates pressure fluctuations in the crank chamber 28 due to the reciprocating motion of the piston 24, and
The blow-by gas from the engine to the crank chamber 28 can be discharged to the carburetor side via the breather 67 which is communicated with the cam chamber 35.
The lubricating oil can be smoothly returned from the cam chamber 35 to the oil pan 51 by maintaining a good pressure balance between the cam chamber 35 and the cam chamber 35.

Note that the breather 67 is configured as follows. That is, the breather 67 has the separation chamber 6
8 is formed, and the cam chamber 35 and the separation chamber 68 are communicated via a discharge pipe 69 and a reed valve 70, and are also communicated via a return pipe 71 and a reed valve 72. Therefore, Breather 67
The blow-by gas is introduced into the separation chamber 68 via the discharge pipe 69 and the reed valve 70, and the lubricating oil component in the blow-by gas separated in the separation chamber 68 is sent to the cam chamber 35 via the return pipe 71 and the reed valve 72. At the same time, the blow-by gas from which lubricating oil components have been removed is sent to the vaporizer 7 via a communication pipe 73.
It is possible to discharge to the 4th side.

Next, the operation of the above embodiment will be explained with reference to FIGS. 7 and 8.

During operation of the internal combustion engine 16, when the lubricating oil pump 37 is driven via the camshaft 36 by the rotation of the crankshaft 29, the lubricating oil in the oil pan 51 is lowered by the driving of the lubricating oil pump 37. The oil is fed under pressure to the oil passage 54 and the upper oil passage 55. The lubricating oil forced into the lower oil passage 54 lubricates the cam bearing of the crankshaft 29 and also passes through the oil passage 58 to the crank pin 3.
After lubricating the big end bearing formed by 1 and the big end 33,
It scatters into the crank chamber 28 and rotates around the crankshaft 29. In addition, a part of the lubricating oil pumped into the upper oil passage 55 lubricates the upper bearing of the crankshaft 29 and also lubricates the big end bearing between the crank pin 31 and the big end 33 through the oil passage 61. Thereafter, it scatters into the crank chamber 28 and is carried around by the crankshaft 29. The lubricating oil circulating around the crankshaft 29 gradually falls and returns to the oil pan 51 via the return oil path 62. Further, the remainder of the lubricating oil forced into the upper oil passage 55 lubricates the bearing and cam surface of the camshaft 36 and then gradually falls and returns to the oil pan 51 via the return oil passage 65.

However, in the above embodiment, the crankshaft 2
In a four-cycle internal combustion engine in which 9 is arranged vertically, the opening of the pressure communication passage 66 on the crank chamber 28 side is provided above the oil level of the lubricating oil in the crank chamber 28, and the opening of the pressure communication passage 66 on the cam chamber 35 side is Since the opening is provided above the oil level of the lubricating oil in the cam chamber 35, the lubricating oil circulating at a constant oil level in the crank chamber 28 and the cam chamber 35 does not enter the pressure communication passage 66. do not have. In addition, ``The engine is moved to the crankshaft 2
When viewed from the axial direction of 9, the pressure communication passage 6
6 is the crankshaft 2 in the cylinder side half of the cross section of the crankshaft 29, with the plane passing through the cylinder center axis as the boundary.
Cylinder case 20 on the side in the same direction as the rotation direction of 9
Since the pressure communication passage 66 is provided on the side, the pressure communication passage 66 does not open into the inner surface of the crank chamber facing substantially tangentially to the rotation of the crankshaft 29. For this reason, the lubricating oil that travels along with the direction of rotation of the crankshaft 29 is blocked by the wall surface of the crankcase because the opening of the pressure communication passage 66 does not exist in the direction of movement of the lubricating oil.
This prevents lubricating oil from entering the pressure communication path 66. Even if the passage area of the pressure communication passage 66 is increased,
The lubricating oil that rotates along with the rotation direction of the crankshaft 29 is blocked by the inner surfaces of the cylinder case 20 and the crank case 21, and the pressure communication path 66 is blocked by the inner surfaces of the cylinder case 20 and the crank case 21. Therefore, the lubricating oil used for lubrication around the crankshaft 29 is immediately returned to the oil pan 51 without passing through the cam chamber 35. Additionally, the passage area of the pressure communication passage 66 can be increased, the pressure balance between the crank chamber 28 and the cam chamber 35 is good, and the return of lubricating oil from the cam chamber 35 to the oil pan 51 becomes smooth. . Therefore, the lubricating oil that has lubricated each part of the internal combustion engine 16 smoothly returns to the oil pan 51, and its cooling is promoted to prevent early deterioration. There is no need to increase the capacity more than necessary. In addition, since the passage area of the pressure communication passage 66 is large, the blow-by gas that has entered the crank chamber 28 can smoothly pass through the pressure communication passage 66 to the cam chamber 3.
5 and further passes through the breather 67 to the vaporizer 74.
It can be discharged to the side.

〔Effect of the invention〕

As described above, according to the present invention, in a four-stroke internal combustion engine in which the crankshaft is vertically placed,
Lubricating the pressure communication path between the crank chamber and the cam chamber while maintaining its original function of maintaining a good pressure balance between the two chambers by allowing air and blow-through gas to freely flow through the pressure communication path. Oil infiltration can be reliably prevented.

[Brief explanation of drawings]

FIG. 1 is a model diagram showing a conventional four-stroke internal combustion engine, FIG. 2 is a side view showing an outboard motor to which an internal combustion engine according to an embodiment of the present invention is applied, and FIG. 3 is a model diagram showing the same internal combustion engine. A cross-sectional view showing the main parts of the engine, Fig. 4 is a cross-sectional view taken along line - of Fig. 3, Fig. 5 is a cross-sectional view taken along line - of Fig. 4, and Fig. 6 is a cross-sectional view taken along line - of Fig. 3.
7 and 8 are model diagrams showing the operation of the internal combustion engine according to the same embodiment, respectively. 16... Internal combustion engine, 28... Crank chamber, 29... Crankshaft, 35... Cam chamber, 36... Camshaft, 62...
Return oil passage, 65...Return oil passage, 66...Pressure communication passage.

Claims (1)

[Claims] 1. A return oil passage is formed between the oil pan and the crank chamber in which the crankshaft is housed vertically, and the cam chamber in which the camshaft is housed, and a pressure connection is established between the crank chamber and the cam chamber. In a four-stroke internal combustion engine that communicates with each other through a passage, the opening on the crank chamber side of the pressure communication passage is provided above the oil level of the lubricating oil in the crank chamber, and the opening on the cam chamber side of the pressure communication passage is provided above the oil level of the lubricating oil in the cam chamber. Installed above the oil level, and with the engine facing the cylinder head above the crankshaft and viewed from the axial direction of the crankshaft, connect the pressure communication passage to the cross section of the crankshaft, with the plane passing through the cylinder center axis as the boundary. A four-stroke internal combustion engine characterized in that the engine is provided on a side of a cylinder case in the same direction as the rotational direction of the crankshaft in the cylinder side half.