JPS59155673A - Reed valve for 2-cycle engine - Google Patents

Abstract

PURPOSE:To improve engine characteristic by forming reeds of reed valve provided in suction path of engine with poly-aramid fiber and resin thereby improving durabilit while suppressing resonance and improving suction efficiency. CONSTITUTION:A partition wall 14 having an opening 14a is provided between carburetor side and combustion chamber side in suction path 9 then a housing 15 for fixing a reed valve 12 is secured through screws 16, 16 to the face at the combustion chamber side while covering the opening 14a. The housing 15 is triangular projecting to the direction of combustion chamber and formed with openings 15a, 15a. Reeds 17 (Composed of resin board containing polyaramid fiber such as meshed cloth) of reed valve 12 are arranged in said openings 15a, 15a and secured together with stopper member 18 at the ends on upper and lower sides of housing 15. Reed 17 will move as shown by imaginary line 17' in accordance to pressure condition at A and B to be partitioned by valve 12 thus to open/close the suction path 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a reed valve for a reed pulp type two-stroke engine.

In order to improve the scavenging efficiency of a two-stroke engine and obtain high output, all pulp is required, and the reed valve is one type of this.

Compared to piston pulp and rotary pulp, reed valves have a timing that automatically changes according to the engine's demands and can obtain good output characteristics over a wide range. However, conventional reed valves with good performance cannot be manufactured. was becoming difficult.

5US631, glass fiber reinforced resin, and the like are used as reed materials for reed valves used in conventional two-stroke engines, and various shapes are used to improve the output characteristics of the engine.

The reed valve flexes smoothly and opens easily when fresh air intake is opened, and on the other hand, when the reed valve closes when the piston descends, the pressure inside the crank booth increases, so it is required to be able to withstand the pressure. . Generally, the characteristics required of a reed valve include high material strength and durability, a wide φ opening area due to negative intake pressure, good intake efficiency, and high durability regarding opening and closing operations.

In addition, with the reed pulp system, when the engine rotates at high speeds, the natural frequency of the reed pulp is low, which causes resonance, which disrupts the timing of opening and closing, lowering the intake air volume, and reducing durability. . Therefore, it is further required to increase the natural frequency of the reed valve, to make the reed valve follow the engine speed well, and to prevent damage due to resonance.

The present inventor has devised the present invention in view of the above-mentioned requirements regarding lead pulp for two-stroke engines.

The purpose of the present invention is to have high material strength and durability, high durability against collisions caused by opening/closing operations, good air intake efficiency, and a high natural frequency to generate resonance. An object of the present invention is to provide a reed valve for a two-stroke engine that prevents this from occurring.

The feature of the present invention is that it is reinforced with polyaramid fibers in order to achieve all of the above objectives. C87 fat plate' (r) It is used as a lead material for IJ-dobulp.

A preferred embodiment of the present invention will be described in detail below with reference to all the accompanying drawings.

FIG. 1 shows a longitudinal sectional side view of a two-stroke engine to which the reed valve of the present invention is applied. In FIG. 1, an engine 1 consists of a crankcase 2, a cylinder block 3, and a cylinder head 4. A crankshaft 5 is housed in the crankcase 2, and a slidable piston 6 is inserted into the cylinder block 3. It is connected with connecting rod 7. The cylinder/double block 3 is formed with an intake passage 9, an exhaust passage 10, and a scavenging passage 11 that communicate with the internal combustion chamber 8.The intake passage 9 is provided with a one-way valve that opens during intake and closes during the explosive combustion process. A reed valve 12 is provided. The reed valve 12 is disposed downstream of the carburetor 13 and opens and closes the intake passage periodically in accordance with the movement of the piston.

Next, the structure of the main parts of the reed valve will be explained based on FIG.

The reed valve 12 is located approximately at the center of the intake passage 9, between the carburetor side and the combustion chamber side, and has a partition wall 1 with an opening 14a fully formed therein.
4, and an opening 14a is provided on the combustion chamber side surface of this partition wall 14.
A housing 15 for attaching the lead pulp is fixed with screws 16 and 16 so as to cover the housing 16. As shown in the drawing, the housing 15 has a substantially triangular cross-section protruding toward the combustion chamber 8, and has openings 15a on its upper and lower surfaces, respectively.

It forms t5a. A reed valve lead 17 is disposed in the openings 15a, 15a at an outer position of the discharge, and the lead 17 is combined with a stopper member 18 that is bent in advance to open toward the downstream direction. , stopper member 1
8 to the outer position and screw 19)・Crank 15
It is fixed to the proximal end of the upper and lower surfaces of.

In the above, A divided by the reed valve 12
Depending on the relationship between the pressure states of and B, the reed 17 comes into close contact with the upper and lower surfaces of the crank 15, and
As shown by the diverticula line 17', it bends and its tip moves away from the upper and lower surfaces, resulting in an open state. However, since it is restricted by the stopper member 18 when it is in the open state, it will not open completely.

The reed valve glue 17 is formed into a plate shape, and the opening 1
It is sufficiently thicker than the opening area of 5a, and has a necessary and sufficient thickness to completely seal it. In the present invention, the material for forming the reed 17 of the reed valve is polyaramid (aromatic polyamide) such as mesh-like cloth.
A resin board (for example, epoxy, unsaturated polyester, etc. is used as the resin) is used, which is formed by containing fibers. In addition to the above, the lead 17 may be made of a composite reinforced resin plate made of polyaramid fibers and other fibers such as glass fiber or carbon fiber, or a resin plate reinforced with polyaramid fibers, depending on the required engine characteristics. For example, SUS
A plate bonded to a metal plate such as 63'l or a titanium alloy plate can be used.

The above aramid fiber has a tensile strength σB of 282 kg, for example.
/mA, bending elastic modulus EB is 6300KY/mA, specific gravity ρ
has a value of 1.44, and has sufficient characteristics as a lead. In other words, when using synthetic resin fibers for the reed, in order to increase the material strength, the tensile strength σB of the fiber and the strength σC of the composite material reinforced with the fiber must be high, and in order to widen the opening area of the reed, The flexural modulus EB of the fiber and the flexural modulus Ec of the composite material reinforced with the fiber are low, and the natural frequency of the reed is high.
In order to improve the durability against knocking (collision with the crank), all fibers can satisfy the binary ρB of the fiber. Other polyaramid fibers also satisfy the above conditions and have sufficient properties to be used as leads.

As is clear from the above description, according to the present invention, the reeds of the reed pulp type two-stroke engine are formed using polyaramid fibers and resin plates, so that they have sufficient durability. It follows the engine speed, does not generate resonance, improves intake efficiency, and exhibits effects such as extremely improving engine characteristics.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a two-stroke engine to which a reed valve according to the present invention is applied, and FIG. 2 is an enlarged vertical cross-sectional view of the reed valve. In the drawings, 1 is an engine, 8 is a combustion chamber, 9 is an intake passage, 12 is a reed valve, 15 is a nozzle, 17 is a reed, and 18 is a stopper member. Patent Applicant Honda Motor Co., Ltd. Agent Patent Attorney 2 1) Part 1 Patent Attorney Kuni Ohashi Intention Patent Attorney 2
Yama Yu Figure 1 Figure 2

Claims (1)

[Claims] 1. A reed valve for a two-cycle engine, characterized in that the reed valve is formed entirely of polyaramid fiber and a resin plate in an engine provided with a reed valve in an intake passage of the engine.