JP2805545B2 - Breather device in V-type two-cylinder internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Industrial application field The present invention relates to a cylinder having a 90-degree bank angle and a right and left V-shape connected to an upper part of a crankcase forming a crankcase.
A crankshaft and a camshaft located above the crankshaft are rotatably supported on the crankcase in parallel with each other, and a piston slidably fitted to each of the cylinders via a crankpin. The present invention relates to a breather device for a V-type two-cylinder internal combustion engine connected to a crankshaft.

(2) Prior Art Conventionally, such an apparatus is known, for example, from Japanese Utility Model Publication No. 56-23456.

(3) Problems to be Solved by the Invention In the above-described conventional device, gears provided on the camshaft and the crankshaft to mesh with each other are housed, and the gear chamber communicating with the crank chamber has a cover on the side surface of the crankcase. A breather chamber is formed between the breather case and an outer surface of the crankcase, the breather case being fixed to the upper wall surface in the gear chamber, and the breather case being fixed to the outer surface of the crankcase covering the outer end of the breather hole. A deflector is provided on the inner surface of the cover so as to cover the inner end of the breather hole. Thus, the breather gas in the gear chamber enters the chamber between the deflector and the cover from a gas inlet provided in the deflector, separates mist-like oil in the chamber, and is then led out of the breather hole to the breather chamber.

According to such a conventional configuration, a deflector for forming a chamber for separating the mist needs to be fixed to the cover or provided integrally with the cover, which complicates the structure.

In addition, the time when the crank chamber communicates with the breather chamber needs to coincide with the time when the pressure in the crank chamber increases, but it is desirable to realize such a time control function with a simple configuration.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide a breather device in a V-type two-cylinder internal combustion engine that enables mist separation with a simple structure and allows the crank chamber to communicate with the breather chamber in accordance with an increase in the pressure in the crank chamber.

B. Configuration of the Invention (1) Means for Solving the Problems In order to achieve the above object, according to the first feature of the present invention, the crankcase outer surface is provided at a position corresponding to one end of the camshaft. A cover forming a breather chamber is fixed between the crankcase and the crankcase. An opening is formed in the camshaft along the radial direction so as to communicate with the crankcase, and a passage extending to one axial end communicates with the opening. Is provided between the one end of the camshaft and the crankcase, on both cylinder sides on a center line passing through the center between the left and right cylinders at right angles to the axis of the crankshaft on a projection plane perpendicular to the crankshaft. A rotary valve is provided for communicating the passage with the breather chamber in accordance with the position of the crankpin.

According to a second feature of the present invention, the rotary valve is configured to open as the opening of the camshaft becomes horizontal.

(2) Operation According to the configuration of the first feature, the gas in the crank chamber is guided from the opening of the camshaft to the breather chamber via the passage and the rotary valve, and further from the breather chamber to the air cleaner. Thus, when the gas is guided from the opening to the passage, the camshaft is rotating, and the opening is along the radial direction of the camshaft. Therefore, the gas from which excess mist has been removed is introduced into the passage. Moreover, since the camshaft is located above the crankshaft, the breather gas can be led out while securing a sufficient height from the oil level in the crankcase.

In a V-type two-cylinder internal combustion engine having a bank angle of 90 degrees,
The pressure in the crank chamber is maximized when the crank pins are located on both cylinder sides on a center line passing through the center between the left and right cylinders at right angles to the axis of the crank shaft. Can be opened to allow gas to escape from the crank chamber to the breather chamber.

According to the configuration of the second feature, in addition to the action of the first feature, when the direction of the opening is in a state where it is difficult for the scattered mist to enter, the rotary valve is opened, so that the gas is removed from the gas. Mist removal can be further promoted.

(3) Example Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a front view of a V-type two-cylinder internal combustion engine, and FIG.
FIG. 3 is a cutaway sectional view taken along the line II-II of FIG.
FIG. 4 is a graph showing a pressure change in the crankcase, taken along a line I-III.

First, in FIG. 1 and FIG. 2, in this V-type two-cylinder internal combustion engine, right and left cylinders 2, 2 arranged in a V-shape at a bank angle of 90 degrees are provided continuously above a crankcase 1, and A crank chamber 3 is formed in the case 1. A crankshaft 4 is rotatably supported on the crankcase 1, and a camshaft 5 connected to and coupled to the crankshaft 4 at a reduction ratio of 1/2 is parallel at a position above the crankshaft 4. It is rotatably supported. The connecting rods 7, 7 connected to the pistons 6, 6, which are slidably fitted to the respective cylinders 2, 2, are connected via the crank pins 4a so as to have a phase difference of 90 degrees in crank angle. It is connected to the crankshaft 4.

At the upper part of the crankcase 1, there is provided a bearing portion 8 forming a blind hole-shaped bearing hole 8a for supporting one end of the cam shaft 5, and the crank portion is formed so as to cover the outer end of the bearing portion 8. A cover 9 is fixed to the upper outer surface of the case 1, and a breather chamber 10 is provided between the outer surface of the crankcase 1 and the inner surface of the cover 9.
Is defined.

One end of the camshaft 5 is rotatably supported in a bearing hole 8a. The camshaft 5 has a passage 11 extending in the axial direction and having both ends closed, and a passage 11 communicating with the passage 11 An opening 12 is formed in the outer surface of the cam shaft 5 along the radial direction. The camshaft 5 has a pair of cylinders 2, 2
Intake and exhaust valves (not shown) provided corresponding to the
Two sets, ie, four cams 13 each corresponding individually
Are provided integrally at an interval from each other, and the opening 12
Open on the outer surface of the cam shaft 5 between a pair of cams 13 adjacent to each other.

With reference to FIG. 3 as well, between the bearing 8 in the crankcase 1 and one end of the camshaft 5, the communication / blocking state of the passage 11 and the breather chamber 10 is set according to the angular displacement of the camshaft 5. A rotary valve 14 for switching is provided. The rotary valve 14 has a valve hole 24 having an axis extending along the radial direction of the camshaft 5 and formed between the inner and outer surfaces of the bearing portion 8, and a passage 11 having an inner end at a position corresponding to the valve hole 24. And a pair of communication holes 25, 25 formed in the camshaft 5 along one diameter line thereof, each time the camshaft 5 is angularly displaced by 180 degrees. The passage 11 communicates with the breather chamber 10 via one of the holes 25 and 25 and the valve hole 24.

The valve hole 24 is formed in the bearing portion 8 with its axis being horizontal. The two communication holes 25, 25 are formed in the camshaft 5 in parallel with the axis of the opening 12.

By the way, the pressure in the crank chamber 3 fluctuates as shown in FIG. That is, when the pistons 6, 6 of the two cylinders 2, 2 are connected to the crankshaft 4 with a phase difference of 90 degrees in crank angle, the pressure change in the crank chamber 3 by the cylinders 2, 2 is indicated by a broken line. And the pressure in the crank chamber 3 as a whole is represented by a curve C obtained by combining the curves A and B, as shown by two curves A and B shown in FIG. It is. Thus, the pressure in the crank chamber 3 is maximized because the center line L passing through the center between the left and right cylinders 2 orthogonal to the axis of the crank shaft 4 on a projection plane perpendicular to the crank shaft 4 When the crank pin 4a is located at a position P (see FIG. 1) on both cylinders 2 and 2 (see FIG. 1), the communication is performed in such an arrangement that the rotary valve 14 is opened at that time. Holes 25, 25 project from camshaft 5.

Referring again to FIG. 3, the cover 9 forming the breather chamber 10 in cooperation with the crankcase 1 is integrally provided with a partition wall 15 so as to cover the upper part of the bearing portion 8.
Due to 15, an outlet chamber 16 is formed in the upper part of the breather chamber 10. A connecting pipe 17 is attached to the cover 9 such that one end thereof protrudes into the outlet chamber 16. One end of a pipe member 18 is connected to the other end of the connecting pipe 17. The end is connected to an air cleaner 20 via a connection pipe 19. Moreover, the connecting pipe 17 is attached to the cover 9 with an axis along one diameter line of the bearing portion 8.
A communication path 21 that connects the breather chamber 10 to the outlet chamber 16 at a position deviated from the axis of 17 is provided in the cover 9.

Further, the crankcase 1 faces the lower part of the breather chamber 10.
A small-diameter return hole 22 for returning the oil accumulated in the lower part of the breather chamber 10 to the inside of the crank chamber 3 is formed.

Next, the operation of this embodiment will be described. During operation of the engine, gas in the crank chamber 3 is introduced into the passage 11 from the opening 12 of the camshaft 5, and the rotary valve 14
The gas in the passage 11 flows into the breather chamber 10 as the valve is opened each time the angular displacement is made by 180 degrees. Since the camshaft 5 is rotating and the opening 12 extends along the radial direction of the camshaft 5, when flowing into the passage 11 from the opening 12, the mist accompanying the gas is centrifuged. The force will act,
Therefore, the excess mist entrained by the gas is suppressed from entering the opening 12 by the action of the centrifugal force, and the gas from which the excess error has been removed is removed from the passage 11 through the rotary valve.
It will be led to the breather chamber 10 via 14.

Moreover, in the breather chamber 10, gas is prevented from flowing into the connection pipe 17 by direct current by the partition 15.
15 flows from the communication passage 21 through the outlet chamber 16 to the connection pipe 17
As a result, the mist in the gas is removed also in the breather chamber 10, and the oil accumulated in the breather chamber 10 is returned to the crank chamber 3 from the return hole 22. become.

Although the rotary valve 14 is a very simple one in which a valve hole 24 is formed in the bearing portion 8 and a pair of communication holes 25, 25 are formed in the cam shaft 5, the rotary valve 14 The valve can be reliably opened in synchronism with the increase in the pressure, and the gas can be guided to the breather chamber 10. Further, the rotary valve 14 opens when the opening 12 is in a horizontal state. When the opening 12 is in a horizontal state, the mist in the crank chamber 3 is in a state where it is most difficult to enter the opening 12. Thus, it is possible to more reliably prevent the mist from entering the passage 11.

Thus, the gas in the crank chamber 3 is released to the air cleaner 20 via the reservoir chamber 10 in accordance with the increase in the pressure in the crank chamber 3. The gas in the crank chamber 3 is supplied to the camshaft 5 located at a higher position than the crankshaft 4.
Is released from the portion corresponding to the above, and the breather function can be performed from a position that is sufficiently higher than the oil level in the crank chamber 3 and the mist entrainment amount in the gas is small.

C. Effects of the Invention As described above, according to the first feature of the present invention, a cover that forms a breather chamber between the crankcase and the crankcase at a position corresponding to one end of the camshaft is provided on the outer surface of the crankcase. The camshaft is provided with an opening in the radial direction to communicate with the crank chamber and a passage communicating with the opening and extending to one end in the axial direction, and the camshaft is provided between the one end of the camshaft and the crankcase. Is equipped with a rotary valve,
At the opening along the radial direction of the rotating camshaft,
By applying centrifugal force to the mist that accompanies the gas, the gas from which excess mist has been removed can escape from the passage through the rotary valve and breather chamber to the air cleaner, ensuring a sufficient height above the oil level in the crank chamber. The mist can be removed with a very simple configuration at the set position and the breather function can be exhibited.

In addition, the rotary valve moves the passage according to the position of the crankpin on both cylinder sides on a center line passing through the center between the left and right cylinders at right angles to the axis of the crankshaft on a projection plane perpendicular to the crankshaft. It communicates with the breather chamber, and with a very simple configuration, the gas in the crank chamber can be led out to the breather chamber in synchronization with the increase in the pressure in the crank chamber.

According to the second aspect of the present invention, in addition to the configuration of the first aspect, the rotary valve is configured to open when the opening of the camshaft is in a horizontal state. In addition to achieving the effect of the first feature, the rotary valve is opened in a state where the mist in the crank chamber is unlikely to enter the opening, and the mist can be more reliably removed.

[Brief description of the drawings]

The drawings show one embodiment of the present invention, and FIG.
FIG. 2 is a sectional view taken along line II-II of FIG. 1, FIG. 3 is a sectional view taken along line III-III of FIG. 2, and FIG. It is a graph which shows a pressure change. 1 ... Crank case, 2 ... Cylinder, 3 ... Crank chamber, 4 ... Crank shaft, 4a ... Crank pin, 5 ...
Camshaft, 6 piston, 9 cover, 10 breather chamber, 11 passage, 12 opening, 14 rotary valve, L center line

Claims (2)

(57) [Claims] A pair of cylinders (2, 2) are connected to each other in a right and left V-shape at a bank angle of 90 degrees on an upper portion of a crankcase (1) forming a crankcase (3). A camshaft (5) located above the crankshaft (4) is rotatably supported on the crankcase (1) in parallel with each other, and is slidably fitted to each of the cylinders (2, 2). In a V-type two-cylinder internal combustion engine in which the combined pistons (6, 6) are connected to a crankshaft (4) via crankpins (4a), a camshaft (5) is provided on the outer surface of the crankcase (1). A cover (9) forming a breather chamber (10) between the crankcase (1) and the crankcase (1) is fixed at a position corresponding to one end of the camshaft (1), and the camshaft (5) is connected to the crankcase (3). An opening (12) extending in the radial direction to pass therethrough and extending to one end in the axial direction in communication with the opening (12) A passage (11), one end of a camshaft (5) and a crankcase (1).
Between the left and right cylinders (2, 2) perpendicular to the axis of the crankshaft (4) on a projection plane perpendicular to the crankshaft (4)
A rotary valve () that connects the passage (11) to the breather chamber (10) according to the position of the crankpin (4a) on both cylinders (2, 2) on the center line (L) passing through the center between the two. 14) A breather device for a V-type two-cylinder internal combustion engine, wherein the breather device is provided. 2. The rotary valve (14) according to claim 1, wherein said rotary valve (14) is configured to open as said opening (12) of said camshaft (5) becomes horizontal. Breather device for a V-type two-cylinder internal combustion engine.