JPS6095132A - Reed valve of 2-cycle internal-combustion engine - Google Patents

Abstract

PURPOSE:To compact the whole volume of an engine by arranging an approx. conical valve seat in such a way as facing the carburettor, and thereby making the pipe length of the suction port from a flange as basis for mounting to the suction hole on cylinder side shorter than that of any conventional construction. CONSTITUTION:Valve seat 5 of a reed valve R.V. is formed approx. conically, and its top faces toward the carburettor 9. Together with a guide cone 10, a valve element 8 is fastened to the inside of seat 5 by a bolt 11. The combustion gas G2 blown back from the cylinder side 3 or crank case is hindered by said valve element 8 so as to prevent counterflow to the carburettor 9 side. The guide cone 10 prevents the after flow phenomenon, in which the mixture gas G1 after being inhaled through the suction hole 5b becomes swirl zone.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reed valve for a two-stroke internal combustion engine.

In a two-stroke internal combustion engine, a reed valve, which is a check valve, is installed in the intake pipe of the crankcase that sucks in the new air-fuel mixture, and the cylinder and crankcase are under high pressure during the expansion stroke of the piston. This prevents the combustion gas inside from flowing back into the carburetor.

An example of the current shape of a reed valve is shown in FIG. 1. A reed valve 1 is assembled to an intake port 3a in the approximate center of an intake passage 4 that communicates a carburetor 2 and a cylinder 3, and has seven cylinders as shown in the figure. A suction port 1 is opened on the outer surface of the valve seat 1a on the cylinder 3 side of the valve seat 1a.
b is brought into contact with an elastic petal-shaped valve body IC that can be opened and closed. Therefore, the new air-fuel mixture from the carburetor 2 (arrow G+ in the figure) pushes open the valve body 1c and is introduced into the cylinder 3 side, and the combustion gas G2 during the expansion process of the piston P is blocked by the valve body 1c. carburetor 2
It acts to prevent the flow from flowing backwards in the upstream direction.

According to this reed valve shape, for the purpose of reducing suction resistance when sucking the air-fuel mixture from the carburetor 2,
Since the reed nozzle 1 itself is shaped like a pyramid to face the cylinder 3 side and follow the flow of the air-fuel mixture, the length of the suction passage 4 corresponds to the length of the reed nozzle 1. The length of the intake port 3a forming the downstream side becomes long.

In other words, the length L+75' of the intake port 3B from the flange flange 1d, which is the mounting base end of the valve seat 1a, to the intake hole 3b of the cylinder 3 becomes relatively long, and therefore the bulk volume of the entire engine increases. There are also circumstances that mean that it has no choice but to grow proportionally. On the other hand, when the shape of the lead nozzle 1 is configured as shown in the figure, the base of the valve body IC is fixed by the set screw 4, and the free tip is opened from the top of the pyramid-shaped valve seat 1a. , due to the blockage, the intake air-fuel mixture G1 from the carburetor 2 flows into the valve body 1c.
, to create a vortex at the position immediately after the valve seat 1a passes, that is, near the top of the valve seat 1a, making it easy to cause a so-called wake phenomenon. As a result, the intake resistance increases, leading to a decrease in intake efficiency and even a decrease in engine output.

The present invention has been made in view of these circumstances, and provides a reed valve for a two-stroke internal combustion engine that aims to improve the air-fuel mixture intake efficiency and reduce the bulk of the engine by further improving the current type reed valve. The purpose is to

To achieve this objective, the present invention is characterized by the following configuration. In other words, the valve seat is formed into a substantially conical shape and has its top facing the carburetor side, and the valve seat opens and closes so that the intake flow through the intake port opened in this valve seat is allowed only in the downstream direction. The reed valve is configured to include a flexible valve body that is brought into close contact with the inner circumferential surface.

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIGS. 2 to 4, the valve seats 5 of the reed valves R and V of the embodiment are formed into a substantially conical shape with a smooth surface at the center, and the entire circumferential surface of the conical portion 5a is filled with air-fuel mixture. A large number of suction ports 5b through which G is conducted are radially bored at equal intervals.
There is C. A flange collar portion 5C at the base end of the conical portion 5a is integrally provided on the outer circumferential surface of the hem portion of the conical portion 5a. These are all molded from Al 4 (or synthetic resin material, etc.), and as shown in Fig. 2, the flange 5C is sandwiched between the suction pipe 6 forming the suction passage and the end on the intake port 3a side of the cylinder 3. It is assembled in an airtight manner using fastening screws 7'', and the top of the conical portion 5a is directed toward the carburetor 9 with the flange flange 5C as the starting point.Therefore, the flange flange at the base end of the installation The distance from 5C to the cylinder suction hole 3b, ie, the pipe length L2 of the intake port 3a, is shorter than that of the conventional type.

On the other hand, a valve body 8 is assembled in close contact with the valve seat 5 formed as described above. In other words, all the suction ports 5 radially opened in the conical portion 5a of the valve seat 5
In order to close and open the valve body 8, the valve body 8 is formed by continuously forming a number of petal-shaped parts 8a corresponding to the number of inlets 5b and petal-shaped parts 8a having a size equal to or larger than those of the inlets 5b. (see Figures (a) and (b)), it has appropriate flexibility and elasticity so that the intake port 5b can be opened and closed by the air-fuel mixture G1 from the carburetor 9, and also allows the intake air flow only in the downstream direction. It is molded from a fibrous substance that has a

Next, the valve seat 5 and the valve body 8 assembled so as to be wrapped inside the valve seat 5 are assembled together with a guide cone 10 formed in the shape of a spindle and shaped like the core of a flower. The reed valves R and V are formed by being tightened together with the long fastening bolts 11. Said Gaitoko-71
0 is shaped into a tapered conical shape as shown in the figure, and the Shinmae Aiki G1 from the carburetor 9 pushes each petal-shaped part 8a of the valve body 8 toward the 7s/da 3 side, and the petal-shaped part 8a Due to its elasticity, it abuts along the streamlined peripheral surface of Kaitoko-710, and the Shinmae Aiki G is drawn in from the intake Qsb of the valve seat 5,
The cylinder 3 is also arranged along the streamlined peripheral surface of the guide cone 10.
It is introduced to the side. On the other hand, as shown in Figure 2, combustion gas is blown back from the cylinder 3 side or the crankcase. , G2 are stopped by the petal-shaped portion 8a of the valve body 8, and have a function as a so-called check valve that prevents backflow to the caprator 9 side, as described above.

Therefore, as understood from the above description, the effects of the present invention will be summarized below.

a) By arranging the substantially conical valve seat 5 to face the carburetor 9, which is completely opposite to the conventional type, the suction hole on the 7 cylinder 3 side is formed from the flange flange 5C, which is the proximal end. The pipe length L2 of the intake port 3a up to the intake port 3a is narrowed to a greater width than that of the conventional type, and as a result, the intake passage 6
This makes it possible to make the overall volume of the engine more compact by shortening the length of the engine, and also contributes to increasing the intake efficiency.

b) Since the shape of the valve seat 5 is conical rather than pyramidal as in the conventional type, it is possible to make the diameter of the suction passage 6, that is, the internal volume, relatively small.

C) By providing the flower core-shaped guide cone 10, the so-called wake phenomenon in which the air-fuel mixture G1 drawn in from the intake port 5b becomes a vortex area is prevented, and the intake resistance is reduced due to the smooth intake flow. Increase efficiency.

d) The valve body 8 is attached to the valve seat 5 using only one fastening bolt 11. By making the part that opens and closes the inlet 5b into the valve body 8 formed from a single continuous plate of petal-shaped parts 8a, there are many petal-shaped parts and bolts required for it as in the conventional type. Only one additional edition material is required.

[Brief explanation of drawings]

Figure 1 is a fragmentary view of the current structure, Figure 2 is a side sectional view of the structure of this example, and Figures 3 (a) and (b) are longitudinal sectional views of the valve seat, which is the main part. Plan view, Figure 4 (a) '+
(b) is also a vertical sectional view and a plan view of the valve body, which is the main part. Explanation of symbols of main parts 3...Cylinder 3a ・Intake bow 1, 5...Valve seat 5a ・Enkei part 5b...Intake port 5C...Flange flange part 6 which is the base end of the installation... - Suction passage 7... Fastening screw 8... Valve body 8a - Petal shaped portion 9... Carburetor 10... Guide cone 11.
- Fastening bolt G1... Intake mixture G2... Combustion gas LV, - Reed valve applicant Honda Motor Co., Ltd. agent Patent attorney Motohiko Fujimura Figure 3 8a'8a

Claims (1)

[Claims] A reed valve for a two-stroke internal combustion engine whose mounting base end is connected to a side end of the intake port in an intake passage communicating between a carburetor and an intake port of a cylinder, the top of which is shaped into a substantially conical shape. a valve seat which is arranged toward the carburetor from the mounting base end and has a plurality of suction ports radially opened on its circumferential surface, and a considerable number of flexible petal-shaped portions at the suction ports of the valve seat. and a valve body that is integrally molded in a radial shape and is assembled on the inner circumferential surface of the valve seat so as to permit the flow of intake air only in the downstream direction. reed valve.