JPH0566226U - 2-cycle engine - Google Patents

Abstract

(57) [Summary] [Purpose] To reliably improve the promotion of scavenging and combustion in a new-flow two-cycle engine having an exhaust valve 8 overhead. An exhaust gas guide groove 10 is provided on the inner wall surface of the valve recess 6 for the exhaust valve 8 in the same tangential direction as the tangential direction of the scavenging port 9 for the cylinder bore 3.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement of a uniflow type two-cycle engine having an exhaust valve in the upper part of the two-cycle engine.

[0002]

[Prior Art]

 Conventionally, in such a uniflow type two-cycle engine having an exhaust valve at the upper part of the head, for example, as described in Japanese Utility Model Publication No. 55-116820, the scavenging port into the cylinder bore is The scavenging flow is set tangentially to the cylinder bore, and a swirl flow is applied to the new intake air from the scavenging port to the cylinder bore to promote scavenging and combustion in the cylinder bore. ing.

[0003]

[Problems to be solved by the device]

 However, in this conventional uniflow two-cycle engine, the swirling flow in the cylinder bore does not occur when the exhaust valve opens, but the scavenging port opens due to the downward movement of the piston, and a new intake air flows from this scavenging port. Of the cylinder bore, in other words, the generation of the swirling flow in the cylinder bore depends exclusively on the inflow of new intake air from the tangential scavenging port. Since the swirl flow inside was weak, achievement of scavenging promotion and combustion promotion by the swirling flow was insufficient.

An object of the present invention is to surely achieve scavenging promotion and combustion promotion by a swirling flow.

[0005]

[Means for Solving the Problems]

 In order to achieve this technical problem, the present invention provides a recessed valve recess in the lower surface of the cylinder head on the upper surface of the cylinder block and provides an exhaust valve in the valve recess, while the cylinder block is provided with the exhaust valve. In a two-cycle engine in which a scavenging port into the cylinder bore is inclined with respect to the cylinder bore in a tangential direction, at least one of the exhaust gas leading guides for exhaust gas is provided on the inner wall surface of the valve recess for the exhaust valve. The exhaust gas guide groove is inclined in the same tangential direction as the tangential direction of the scavenging port.

[0006]

[Work]

 With this configuration, when the exhaust valve starts to open during the downward stroke of the piston, the exhaust gas in the cylinder bore is ejected toward the exhaust port. In this case, since the exhaust gas guide groove is inclined in the tangential direction on the inner wall surface of the valve recess for the exhaust valve, the exhaust gas ejected into the exhaust port at the moment the exhaust valve is opened is Since the exhaust gas guide groove guides the gas while swirling, the swirling flow can be induced in the cylinder bore.

Then, when the scavenging port is opened next to the opening of the exhaust valve, new intake air flows into the cylinder bore tangentially through the scavenging port, so that a swirl flow can be imparted to the cylinder bore. You can.

[0008]

[Effect of the device]

 Thus, according to the present invention, it is possible to induce a swirl flow in the cylinder bore before introducing new intake air tangentially from the scavenging port into the cylinder bore. Since the swirl flow can be given in advance before the introduction of the new intake air, the swirl flow in the cylinder bore can be significantly improved as compared with the conventional case, so that the scavenging is promoted. And, it has an effect that the promotion of combustion can be reliably achieved.

[0009]

Embodiment An embodiment of the present invention will be described below with reference to the drawings. In the figure, reference numeral 1 denotes a cylinder block in which a cylinder bore 3 with a built-in piston 2 is formed, and reference numeral 4 denotes a cylinder head in which a gasket 5 is fastened to the upper surface of the cylinder block 1.

A valve recess 6 is formed in the lower surface of the cylinder head 4 at a substantially central portion of the cylinder bore 3, while an exhaust port 7 is provided inside the cylinder head 4 to form the valve recess 6. An exhaust valve 8 is formed at the opening of the exhaust port 7 into the valve recess 6. Further, the cylinder block 1 is provided with a plurality of scavenging ports 9 which are opened in the middle of the downward stroke of the piston 2 so as to be opened tangentially to the cylinder bore 3. In the middle of the downward stroke, first, the exhaust valve 8 is opened, and then the scavenging ports 9 are opened to introduce new intake air into the cylinder bore 3.

Then, on the inner wall surface of the valve recess 6 for the exhaust valve 8, exhaust gas guide grooves 10 for guiding the exhaust gas into the valve recess 6 are provided at a plurality of positions in the circumferential direction thereof, and the scavenging ports 9 are provided. It is provided with an inclination in the same tangential direction as the tangential direction of. In this configuration, when the exhaust valve 8 starts to open during the downward stroke of the piston 2, the exhaust gas in the cylinder bore 3 is ejected toward the exhaust port 7. In this case, a plurality of exhaust gas guide grooves 10 are provided on the inner wall surface of the valve recess 6 with respect to the exhaust valve 8 so as to be inclined in the tangential direction, so that the exhaust port 8 faces the inside of the exhaust port 7 at the moment of opening. The exhaust gas ejected as a result of the guide action of each of the exhaust gas guide grooves 10 is ejected while swirling as shown by an arrow A in the figure, whereby a swirling flow is induced in the cylinder bore 3. be able to.

When each scavenging port 9 is opened following the opening of the exhaust valve 8, new intake air flows into the cylinder bore 3 tangentially through the scavenging port 9, so that the inside of the cylinder bore 3 is closed. In addition, a swirling flow can be imparted as indicated by arrow B in the figure.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing an embodiment of the present invention.

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

FIG. 3 is a bottom view taken along the line III-III in FIG.

[Explanation of symbols]

 1 Cylinder Block 2 Piston 3 Cylinder Bore 4 Cylinder Head 6 Valve Recess 7 Exhaust Port 8 Exhaust Valve 9 Scavenging Port 10 Exhaust Gas Induction Groove

Claims (1)

[Scope of utility model registration request] 1. A valve recess is formed in a lower surface of a cylinder head on an upper surface of a cylinder block, and an exhaust valve is provided in the valve recess. In a two-cycle engine that is provided tangentially with respect to a cylinder bore, at least one exhaust gas guide groove for guiding exhaust gas into the valve recess is formed on an inner wall surface of the valve recess for the exhaust valve. A two-cycle engine characterized by being provided with an inclination in the same tangential direction as the tangential direction of.