JPH08246838A - Motive power loss reducing device for engine - Google Patents

Abstract

PURPOSE: To improve engine performance, and prevent lubricating oil in a crankcase from leaking out by pressure in this crankcase by preventing a piston from uselessly changing air pressure in the crankcase when the piston reciprocates by driving of an engine. CONSTITUTION: A communicating passage 32 is arranged to communicate the inside of a crankcase 2 and an exhaust passage 23 with each other. A one-way valve 33 is arranged to allow only a flow running toward the exhaust passage 23 from inside of the crankcase 2 among a flow of fluid in this communicating passage 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine power loss reduction device.

[0002]

2. Description of the Related Art Usually, an engine (internal combustion engine) is slidably fitted in a crankcase which has a crankshaft therein and supports it, a cylinder protruding from the crankcase, and a cylinder hole in the cylinder. The combustion chamber is defined by a piston and a connecting rod that connects the piston and the crankshaft to each other, and a space surrounded by the cylinder and the piston in the cylinder hole.

When the engine is driven, a mixture of fuel and air is combusted in the combustion chamber, and its thermal energy causes the crankshaft, the piston, and the connecting rod to interlock, and the piston in the cylinder hole. Can be reciprocated. As a result, the crankshaft is rotated in one direction to enable output.

[0004]

By the way, since the inside of the crankcase and the cylinder hole communicate with each other,
When the piston reciprocates in the cylinder hole due to the driving of the engine, the piston repeatedly advances and retracts toward the inside of the crankcase, whereby the air pressure inside the crankcase is changed.

When the air pressure in the crankcase is fluctuated in this manner, power loss increases, which hinders improvement in engine performance.

Further, the bottom of the crankcase is
Lubricating oil for lubricating the inner peripheral surface of the cylinder hole and the sliding contact portion with the piston is stored, but when the inside of the crankcase is pressurized by the operation of the piston, this pressure is used. Part of the lubricating oil scattered in the crankcase may leak through the mating surface between the crankcase and the cylinder.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and when the piston reciprocates by driving the engine, the piston unnecessarily fluctuates the air pressure in the crankcase. It is an object to prevent the lubricating oil in the crankcase from leaking out by the pressure in the crankcase, while preventing the engine from improving the engine performance.

[0008]

In order to achieve the above object, the power loss reducing apparatus for an engine according to the present invention is provided with a communication passage 32 for communicating the inside of the crankcase 2 and the exhaust passage 23 with each other. Of the fluid flow in 32, the exhaust passage 2 from the inside of the crankcase 2 is the same as above.
A one-way valve 33 that allows only the flow toward 3 is provided.

[0009]

[Operation] The operation of the above configuration is as follows.

When the engine 1 is driven, the cylinder hole 12
When the piston 16 reciprocates inside (arrow A in FIG. 2),
This piston 16 is used in the crank chamber 5 in the crankcase 2.
The crankcase 2
I try to change the internal air pressure.

However, the inside of the crankcase 2 is communicated with the exhaust passage 23 by the communication passage 32 and the one-way valve 33, and the negative pressure of the exhaust pulsation in the exhaust passage 23 causes the fluid in the crankcase 2 to flow. Certain air is sucked toward the exhaust passage 23 (arrow C in FIG. 1), so that the inside of the crankcase 2 is made a negative pressure.

Therefore, as described above, even if the piston 16 repeatedly advances toward and retracts from the crankcase 2, the air pressure in the crankcase 2 is negative,
The occurrence of pressure fluctuations in the air is suppressed, and the reciprocating movement of the piston 16 is prevented from causing unnecessary fluctuations in the air pressure in the crankcase 2.

[0013]

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

In FIGS. 1 and 2, reference numeral 1 is a multi-cylinder (4-cylinder) four-cycle engine (internal combustion engine), which is mounted on a motorcycle or automobile and used as a drive source for traveling.

The engine 1 has a crankcase 2. The crankcase 2 is constituted by an upper case 3 and a lower case 4 which are detachably coupled in the vertical direction, and the inside of the crankcase 2 is a crank chamber 5. It is said that.

A crankshaft 7 is provided in the crank chamber 5, and the crankshaft 7 is sandwiched between the mating surfaces of the upper case 3 and the lower case 4 and supported by a bearing 8. The crankshaft 7 has its shaft. It is supposed to be rotatable around its core 9.

The cylinder 1 is mounted on the upper surface of the crankcase 2.
1 is projected. This cylinder 11 is multiple (4)
A cylinder body 13 having a cylinder hole 12 and a cylinder head 14 which is detachably attached to an upper end which is a protruding end of the cylinder body 13. The axes of the cylinder holes 12 are oriented vertically and parallel to each other. Further, the lower end of each cylinder hole 12 opens toward the crank chamber 5 and communicates with the crank chamber 5, and the upper end of each cylinder hole 12 is closed by the cylinder head 14 as above.

A piston 16 is slidably fitted in each cylinder hole 12 in the axial direction of each cylinder hole 12, and each piston 16 and the crank shaft 7 are connected to each other by a connecting rod 17. There is. A space surrounded by the cylinder 11 and the piston 16 in the cylinder hole 12 is a combustion chamber 18.

The outside of the cylinder 11 is connected to the combustion chamber 18
An intake passage 19 communicating with the intake passage 1 is provided.
On the upstream end side of 9, a carburetor 21 and an air cleaner 22 are sequentially connected. On the other hand, the combustion chamber 18 is connected to the cylinder 1
An exhaust passage 23 that communicates with the outside of the vehicle 1 is provided.

When the piston 16 slides in the cylinder hole 12 toward the crank chamber 5 when the engine 1 is driven, the combustion chamber 18 and the intake passage 19 become negative pressure,
The air 25 outside the cylinder 11 is transferred to the air cleaner 22.
It is sucked into the carburetor 21 side through. This vaporizer 2
The fuel 26 is supplied by the carburetor 21 to the air 25 sucked in 1 to generate the air-fuel mixture 27, and the air-fuel mixture 27 is sucked into the combustion chamber 18 through the intake passage 19.

In the combustion chamber 18, the air-fuel mixture 27 is ignited by a spark plug and burned, and the thermal energy of the air-fuel mixture 27 is applied to the crankshaft 7, the piston 16 and the connecting rod 1.
7 are interlocked with each other, and the piston 16
Are reciprocated (arrow A in FIG. 2). As a result, the crankshaft 7 is rotated in one direction (arrow B in FIG. 2), and the power of the engine 1 can be output via the output chain wheel 29 which is an output unit. Further, the gas after the air-fuel mixture 27 is burned in the combustion chamber 18 is discharged to the outside of the cylinder 11 as the exhaust gas 28 through the exhaust passage 23.

In the lower case 4 of the crankcase 2, the bottom of the crank chamber 5 is an oil pan, in which the lubricating oil 30 is stored. The lubricating oil 30 is used for each bearing 8 and the inner peripheral surface of the cylinder hole 12 and the piston 16
It is sent to the sliding contact part with and lubricates them.

A communication passage 32 for communicating the upper portion of the crank chamber 5 in the crankcase 2 with the exhaust passage 23 near the combustion chamber 18 is provided, and the communication passage 32 is formed of a flexible pipe material. Has been done. In addition, this communication passage 3
Among the fluid (mainly air) flows in No. 2, a one-way valve 33 that allows only one-way flow (arrow C in FIG. 1) from the inside of the crankcase 2 toward the exhaust passage 23 is provided. . The one-way valve 33 is provided in the middle of the communication passage 32 in the longitudinal direction, and the one-way valve 33 is a reed valve.

As described above, when the piston 16 reciprocates in the cylinder hole 12 by the drive of the engine 1 (arrow A in FIG. 2), the piston 16 faces the crank chamber 5 in the crankcase 2. The air pressure in the crankcase 2 is changed by repeatedly advancing and retreating.

However, the inside of the crankcase 2 is communicated with the exhaust passage 23 by the communication passage 32 and the one-way valve 33, and the negative pressure of the exhaust pulsation in the exhaust passage 23 causes the fluid in the crankcase 2 to flow. Is sucked toward the exhaust passage 23 (arrow C in FIG. 1), whereby the inside of the crankcase 2 is made to have a negative pressure or is made to have a negative pressure.

Therefore, as described above, even if the piston 16 repeatedly advances and retracts toward the inside of the crankcase 2, the air pressure in the crankcase 2 is negative (for example, a negative pressure).
-250 mmHg), or the amount of negative pressure is directed, the occurrence of pressure fluctuation (pulsation) in the air is suppressed, and the reciprocating movement of the piston 16 causes the air pressure in the crankcase 2 to fluctuate unnecessarily. Is prevented, that is,
Generation of power loss (pumping loss) is prevented.

The operations of the pistons 16 of the multi-cylinder engine 1 described above are mutually phase-shifted. For this reason, when each piston 16 repeatedly advances and retracts toward the inside of the crankcase 2 and the inside of the crankcase 2 is about to be compressed due to the advance of one piston 16, the other piston 16 retracts to cause the above compression. Therefore, the fluctuation of the air pressure in the crankcase 2 is suppressed to some extent in advance without the action of the communication passage 32 or the one-way valve 33.

On the other hand, when the engine 1 is a single cylinder, when the piston 16 advances toward the inside of the crankcase 2 and the inside of the crankcase 2 is compressed, this pressure is not absorbed by the other pistons. , The pressure of this compression tends to increase. Therefore, in such a single-cylinder engine 1, the power loss during driving may be large.

Therefore, if the single-cylinder engine 1 is provided with the communication passage 32 and the one-way valve 33 described above, the decrease in power loss is significantly prevented as compared with the multi-cylinder engine, and a dramatic improvement in engine performance is achieved. To be done.

An oil separator 3 is provided above the crankcase 2.
4 is provided, and the oil separator 34 is provided at a midway portion in the longitudinal direction of the communication passage 32 extending from the crank chamber 5 to the one-way valve 33. The inside of the oil separator 34 has a labyrinth shape, and when the fluid passes through the inside of the oil separator 34, the lubricating oil 30 is separated from the air, and the lubricating oil 30 naturally flows through the oil return passage 35. Then, it is returned to the crank chamber 5 (arrow D in FIG. 1).

Therefore, it is possible to prevent the lubricating oil 30 from being wasted.

2 to 7, the crankshaft 7 is
Is a crank spindle 38 supported on the crankcase 2 by the bearing 8 and located on the axis 9 thereof, and a crank web 39 radially outwardly projecting from the crank spindle 38.
And a crank pin 40 supported by the crank web 39 at a position eccentric from the crank main shaft 38. One end (large end) of the connecting rod 17 is connected to the crank pin 40, and the other end (small end) of the connecting rod 17 is connected to the piston 16.

A chamfered portion 41 is formed by chamfering a side edge of a front end portion of each crank web 39 in the rotation direction of the crank shaft 7 (arrow B in the drawing). This allows
The cross section of each front end portion of each crank web 39 in the rotational direction is tapered forward in the rotational direction.

In this case, the chamfered portions 41 of the crank webs 39 shown in FIGS. 3 to 7 and the chamfered portions 41 of the crank web 39 shown in FIG. I am doing it.

As described above, by forming the chamfered portion 41 on each crank web 39, the rotating crank shaft 7 causes the air in the crank chamber 5 to scatter with the lubricating oil 30 scattered.
The resistance force received from the engine is reduced, and unnecessary power loss is suppressed, resulting in improved engine performance.

[0036]

According to the present invention, a communication passage for communicating the inside of the crankcase with the exhaust passage is provided, and
Of the fluid flow in the communication passage, a one-way valve that allows only the flow from the inside of the crankcase toward the exhaust passage is provided. Therefore, the following effects are obtained.

That is, when the piston reciprocates in the cylinder hole due to the driving of the engine, the piston repeatedly advances and retracts toward the crank chamber in the crankcase, and tries to change the air pressure in the crankcase. To do.

However, the inside of the crankcase is communicated with the exhaust passage by the communication passage and the one-way valve, and the negative pressure of the exhaust pulsation in the exhaust passage causes the air, which is the fluid in the crankcase, to flow into the exhaust passage. Is sucked toward the inside of the crankcase, so that the inside of the crankcase has a negative pressure.

Therefore, as described above, even if the piston repeatedly advances and retracts toward the inside of the crankcase, the air pressure in the crankcase is a negative pressure, so that the occurrence of pressure fluctuation in the air is suppressed. It

As a result, the reciprocating movement of the piston is prevented from unnecessarily changing the air pressure in the crankcase, the increase in power loss is suppressed, and the engine performance is improved.

Further, as described above, since the inside of the crankcase has a negative pressure, it is possible to prevent the lubricating oil in the crankcase from leaking out from the crankcase.

Further, as described above, since the inside of the crankcase has a negative pressure, there are the following effects.

For example, when the crankshaft is penetrated through the through holes formed in the wall of the crankcase, and the seal material is press-fitted between the inner peripheral surface of these through holes and the outer peripheral surface of the crankshaft. In the case where the amount of the lubricating oil leaking to the outside through the sealing material may be the same between the case where the communication passage and the one-way valve are not provided and the case where the one-way valve is provided,
In the case where the communication passage and the one-way valve are provided, the pressure of the sealing material can be reduced because the pressure inside the crankcase is negative and the leakage is suppressed.

Therefore, also by this, the power loss is reduced and the engine performance is improved.

Moreover, in addition to the above-mentioned improvement in engine performance,
The effect of preventing the leakage of the lubricating oil was obtained by using the exhaust pulsation, and there is no separate pump or the like for making the inside of the crankcase negative pressure.
There is also an advantage that the above-mentioned effects can be obtained with a simple configuration.

[Brief description of drawings]

FIG. 1 is an overall diagram of an engine.

FIG. 2 is a sectional view taken along the line 2-2 of FIG.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;

4 is a cross-sectional view taken along the line 4-4 of FIG.

5 is a view taken along line 5-5 of FIG.

6 is a sectional view taken along the line 6-6 of FIG.

7 is a cross-sectional view taken along the line 7-7 of FIG.

[Explanation of symbols]

 1 Engine 2 Crankcase 5 Crank Chamber 7 Crankshaft 8 Bearing 9 Shaft Center 11 Cylinder 12 Cylinder Hole 16 Piston 17 Connecting Rod 18 Combustion Chamber 23 Exhaust Passage 25 Air 26 Fuel 27 Mixture 28 Exhaust 30 Lubricating Oil 32 Communication Passage 33 One-way valve

Claims (1)

[Claims] 1. A communication passage that connects the inside of the crankcase and the exhaust passage to each other is provided, and among the fluid flows in the communication passage, only the flow from the inside of the crankcase toward the exhaust passage is allowed. Engine power loss reduction device with directional valve.