JPS603943Y2 - Internal combustion engine intake system - Google Patents

Description

[Detailed description of the invention] This invention relates to an intake system for an internal combustion engine used in small models such as motorcycles, and utilizes the pulsating pressure generated in the crankcase during engine operation effectively to increase the intake stroke. The purpose is to increase the amount of intake air during combustion, improve combustion efficiency, and improve output.

To explain the embodiment with reference to the drawings, in Fig. 1, 1 is a cylinder of a four-stroke engine, 2 is a cylinder head, 2a is a combustion chamber, and 3 and 4 are intake passages and exhaust holes bored in the cylinder head 2. 5 is a piston, 6 is a crankcase that continues below the cylinder 1, and includes an intake passage 3.
An intake valve 3a is arranged at the outlet end of the exhaust passage 4 to partition it from the combustion chamber 2a, and an exhaust valve 4a is arranged at the inlet end of the exhaust passage 4 to partition it from the combustion chamber 2a. valve 3a
, 4a is a rotary cam 7a installed on the cylinder head 2.
, 7b alternately open and close the intake passage 3 and the exhaust passage 4 at required times in relation to the vertical movement of the piston 5 via the rocker arms 8a and 8b, but such a configuration is different from the conventional one. It's no different than anything else.

By the way, in this invention, a through hole 9 is formed on the intake side of the cylinder head 2 near the intake valve 3a, and opens into the intake passage 3 and is inclined toward the outer circumferential wall of the combustion chamber 2a as shown in FIG. This through hole 9 is connected to a replenishment pump device 11 mounted on the crankcase 6 via a nozzle pipe 10a and a connecting pipe 10b.

This replenishment pump device has a cover 11a that also serves as a joint pipe and a passageway that directly communicates with the inside of the crankcase 6.
A plate-shaped piston 12 is fitted into the inside of this casing Ilb, and springs 13a and 13b of a required strength are disposed in the upper and lower parts of the piston 12, so that when the piston 12 is not in operation, the piston 12 are placed in a neutral position by their springs 13a, 13b.

Reference numeral 14 denotes a breather chamber provided in the crankcase 6, which communicates with the outside air through a ventilation pipe 15. A one-way valve 16, for example, a reed valve, which opens only to the atmosphere is provided at the entrance of the chamber. There is.

However, the one-way valve 16 may be provided at any other position as long as it can release positive pressure when the inside of the crankcase 6 becomes positive due to pulsating pressure.

Based on this configuration, the exhaust valve 4 is closed during the intake stroke of the engine.
a closes, the intake valve 3a opens as shown by the dotted line in the figure, and the piston 5 descends, creating a predetermined negative pressure in the intake passage 3. The interior of the cover 11a of the replenishment pump device 11 and the upper chamber of the casing Ilb, which are in communication, also become negative pressure, and due to the negative pressure action, the plate-shaped piston 12 in the casing 11 resists the spring force of the springs 13a and 13b. Dotted line 12'
It is pulled toward the intake passage 3 side as shown in FIG.

When the next stroke (compression) begins and the intake valve 3a closes, the plate-shaped piston 12 in the casing 11 is moved by the springs 13a, 1
Due to the restoring force of 3b and the negative pressure generated in the crankcase 6, it moves to the original position or slightly beyond this to the crankcase 6 side, and the volume on the intake passage 3 side in the casing 11 increases, so that the intake air The intake action continues even after the valve 3 is closed, filling the casing 11 with air-fuel mixture and preparing it for the next intake stroke.

Following this, expansion and exhaust strokes are performed, and pulsating pressure is generated within the crankcase 6, but during this time, the intake valve 3
a is closed, and the positive pressure generated in the crankcase 6 (including the gas pressure) opens the one-way valve 16 and is released from the air breather chamber 14 to the atmosphere, and the casing 11
Since only negative pressure acts on the lower surface of the plate-shaped piston 12 inside, the plate-shaped piston 12 maintains a retracted state and does not affect the stored air-fuel mixture.

Then, when the next intake stroke begins and the intake valve 3a opens again,
The air-fuel mixture stored in the casing llb of the replenishment pump device 11 according to the air-fuel mixture from the carburetor C is transferred to the plate-shaped piston 12.
As a result, the volumetric efficiency of the engine can be increased accordingly.

In addition, at this time, since the through hole 9 provided in the cylinder head 2 is inclined toward the outer circumferential wall of the combustion chamber 2a, the intake air-fuel mixture swirls along the wall surface of the combustion chamber 1a, and actively moves inside the combustion chamber. Since the vortex flow is created as a raw material, the air-fuel mixture is homogenized and combustion is promoted.

Note that even if a flexible diaphragm is provided in the replenishment pump device 11 in place of the plate-shaped piston 12, the function of replenishing the air-fuel mixture remains the same.

Furthermore, Fig. 3 shows an example in which the above-mentioned intake system is applied to a motorcycle equipped with a single-cylinder internal combustion engine, where E is the internal combustion engine, C is the crankcase with a built-in transmission,
K is a carburetor, A is an air cleaner, F is a frame, 1 is an exhaust muffler, 10a and 10b are the above-mentioned nozzle pipe and connecting pipe, and 11 is a replenishment pump device.

As described above, in an internal combustion engine with an intake valve and an exhaust valve in the cylinder head, the cylinder head is provided with a through hole that opens into the intake passage near the intake valve and slopes toward the combustion chamber. The casing of the replenishment pump device connected to the casing is partitioned by a spring-supported reciprocating member, one partitioned chamber is communicated with the inside of the crankcase through a passage, and the other partitioned chamber is communicated with the above-mentioned through hole. A one-way valve that opens only to the atmosphere is installed inside the engine, so that the required amount of air-fuel mixture is reliably stored in the make-up pump device by the action of the pulsating pressure, especially negative pressure, generated in the crankcase when the engine is operating. During the intake stroke, the air-fuel mixture stored in the make-up pump device can be fed into the cylinder along with the air-fuel mixture from the carburetor, reducing engine pumping loss and increasing volumetric efficiency and output. can be increased,
Furthermore, uniform stirring of the air-fuel mixture within the combustion chamber is promoted, and combustion efficiency can be improved.

[Brief explanation of the drawing]

Figure 1 is a sectional view of an embodiment of this invention, and Figure 2 is its X-
A plan sectional view along the X-ray, and FIG. 3 is a schematic side view of an example applied to a motorcycle. In the figure, 1...Cylinder, 1a...Combustion chamber, 2...Cylinder head, 3...Intake passage, 3a...Intake Valve, 4...Exhaust passage, 4a...Exhaust valve, 5...Piston, 6...Crankcase, 9...Through hole , 10a...nozzle pipe, 10b...
Connecting pipe, 11... Replenishment pump device, 12...
... Plate-shaped piston, 13a, 13b ... Spring, 14 ... Air breather chamber, 16 ... One-way valve.

Claims (1)

[Scope of utility model registration request] In an internal combustion engine in which the cylinder head 2 is equipped with an intake valve 3a and an exhaust valve 4a, the cylinder head 2 has a through hole 9 that opens into the intake passage 3 near the intake valve 3a and slopes toward the outer peripheral wall of the combustion chamber 2a. The casing llb of the replenishment pump device 11 connected to the crankcase 6 is partitioned by a reciprocating member supported by a spring, and one partitioned chamber is communicated with the inside of the crankcase 6 by a passage 11c, and the other partitioned chamber is connected to the crankcase 6. The air intake system for an internal combustion engine is provided with a one-way valve 16 that communicates with the through hole 9 and opens only to the atmosphere inside the crankcase 6.