JPH04203212A - Intake device for internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce intake resistance during high-speed rotation by providing a lead valve which allows intake to flow in a direction of a cylinder only in an intake passage, keeping a lead of the lead valve under a fully-open condition by means of an electromagnet or the like when the rotational number of an internal combustion engine is a specified value or higher. CONSTITUTION:During low rotation of an engine, a small opening rate of a lead 6d is enough because a required intake amount is small. Intake resistance at this time is small, so that a required intake is obtained. Backflow of the intake is prevented by a lead valve 6. When engine speed is increased to be an engine speed value N where torque gaining rate by the prevention of backflow of the intake is equalized to a torque losing rate by the intake resistance at the time of opening the lead 6d through the intake, an electromagnet 7 is operated. The lead 6d is thus attracted to an attraction part 7a of the electromagnet 7 and kept under a fully-open condition. Intake resistance at the time of opening the lead 6d through the intake is eliminated, and a sufficient intake amount is obtained according to engine speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an intake system for an internal combustion engine having a Riet valve for preventing backflow in an intake passage.

[Conventional technology]

An intake system for an internal combustion engine in which a reed valve having a polygonal pyramidal body is provided in an intake passage is described in Japanese Utility Model Application Publication No. 64-25424.

This is because when the engine is running at low speeds, the reed valve prevents intake air from flowing backwards, and when the engine is running at high speeds, the reed valve has a polygonal pyramidal body, so the opening shape of the body is The shape of the reed valve can be approximated to a circular shape as a whole, thereby reducing shape loss of the reed valve.

[Problem to be solved by the invention]

The above-mentioned reed valve can improve the intake volume efficiency compared to a normal reed valve because the opening shape of the main body is close to a circle, but the reed is still opened by intake air, so the intake resistance at that time is still high. exists.

The intake resistance due to the reeds increases as the reeds become more open, and therefore, the higher the engine speed becomes, the more the intake air becomes insufficient.

SUMMARY OF THE INVENTION An object of the present invention is to provide an intake system for an internal combustion engine that maintains the function of preventing backflow of intake air at low engine speeds while providing sufficient intake air even at maximum engine speeds.

[Means to solve the problem]

In order to achieve the above-mentioned object, an intake system for an internal combustion engine according to the present invention has a reed valve in an intake passage communicating with an intake valve of a cylinder that allows intake air to flow only toward the cylinder. The reed valve is characterized in that the reed of the reed valve is held in a fully open position by an electromagnet or the like when the rotational speed exceeds a predetermined number of revolutions.

[For production]

With the above structure, the reed valve can prevent the intake air from flowing backwards when the engine is running at low rotation speeds, and the engine speed increases, resulting in increased torque due to the prevention of the intake air backflow and the intake air opening the reed valve. When the rotational speed reaches a point where the reduction in torque due to the intake resistance is equal, the reed of the reed valve is held in the fully open position by an electromagnet or the like.

As a result, the above-mentioned intake resistance disappears above that rotation speed, and sufficient intake air can be obtained even at maximum rotation.

〔Example〕

In FIG. 1, reference numeral 1 indicates an intake valve, and 2 indicates an intake passage that communicates the intake valve 1 with a surge tank (not shown). The intake passage 2 is formed from a cylinder head 3, an intake pipe 4 connected to a surge tank, and a connecting pipe 5 connecting the cylinder head 3 and the intake pipe 4. The flange 6a of the reed valve 6 is hermetically fastened therebetween.

The reed valve 6 has a plurality of inclined surfaces 6b extending from the flange 6a into the connecting pipe 5, and each inclined surface 6b is provided with an opening 6C. Each opening 6C as a whole is
It is formed to reduce the shape loss of the intake air.

The connecting pipe 5 has a curved surface that gradually widens toward the side where the reed valve 6 is attached, and a lead 6d is cantilevered between this curved surface and the reed valve inclined surface 6b so as to cover the opening. . The curved surface of the connecting tube 5 acts as a stopper to prevent excessive curvature of the lead 6d. A hole 5a is provided in the connecting tube 5 at a position where the tip of the lead 6d comes into contact with the hole 5a.
The same number of electromagnets 7 as the leads 6d are airtightly attached to the outside of the connecting pipe so that the attracting portions 7a of the electromagnets 7 are inserted into the holes 5a.

The intake system for the internal combustion engine of this embodiment operates as follows.

When the engine is running at a low rotation speed, the required amount of intake air is small, so the opening amount of the reed 6d may be small.

Therefore, since the intake resistance at that time is small, the necessary intake air can be obtained, and the reed knob 6 prevents the intake air from flowing backward.

The electromagnet 7 is activated when the engine speed increases and reaches a speed N at which the increase in torque due to the prevention of backflow of intake air is equal to the decrease in torque due to the intake resistance when the intake air opens the lead 6d. let As a result, the lead 6d is attracted to the attraction portion 7a of the electromagnet 7 and held at the fully open position. Therefore, when the rotation speed is equal to or higher than the rotation speed N, there is no intake resistance when the intake lead 6d is opened, and a sufficient amount of intake air corresponding to the rotation speed can be obtained.

Furthermore, in this embodiment, if the reed 6d is used which resonantly vibrates at the predetermined rotational speed N, the reed 6d approaches the adsorption portion 7a of the electromagnet 7 by itself due to the resonant vibration. If the electromagnet 7 is already activated, the reed can be easily held in the fully open position even with a weak magnetic force.
The same effects as described above can be achieved with less power consumption or smaller electromagnets.

〔Effect of the invention〕

As described above, according to the intake system for an internal combustion engine of the present invention, the same torque as before is maintained until the rotation speed at which the increase in torque due to prevention of backflow of intake air and the decrease in torque due to intake resistance when opening the intake reed are equal. Since the reed is held in the fully open position by an electromagnet in the rotation range beyond which there is no intake resistance when the intake air pushes the reed open, it is possible to obtain a sufficient amount of intake air up to the maximum rotation. , it is possible to obtain higher torque than before.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an intake system for an internal combustion engine according to the present invention, and FIG. 2 is a graph showing the relationship between torque and rotational speed. 1... Intake valve, 2... Intake passage, 5...
Connecting pipe, 6... Reed valve, 6d...
Lead, 7...Electromagnet.

Claims (1)

[Claims] There is a reed valve in the intake passage that communicates with the cylinder's intake valve that allows intake air to flow only toward the cylinder, and when the internal combustion engine is at a predetermined rotation speed or higher, the lead of the reed valve is held in the fully open position by an electromagnet or the like. An intake device for an internal combustion engine, characterized in that it is configured to.