JPS6359010B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a two-stroke engine. Among reciprocating internal combustion engines, two-stroke engines have a simple structure, have small torque changes, and can provide high specific output.

[Prior Art] A conventional two-stroke engine uses a crank mechanism to extract rotary motion output from the reciprocating motion of a piston.

[Problems to be Solved by the Invention] For this reason, engines have become relatively large and heavy. For this reason, there is a strong demand for smaller and lighter engines, as well as higher efficiency.

The present invention replaces the crank mechanism of a two-stroke engine with a piston drive mechanism using rolling balls and guide grooves,
The purpose is to reduce the size and weight of the engine body, perform efficient scavenging and exhaust, and increase output and improve thermal efficiency.

[Means for Solving the Problem] Corresponding to this object, a two-stroke engine in which a piston is driven by a rolling ball and a guide groove according to the present invention includes a cylinder, a piston that fits into the inner surface of the cylinder, and an inner surface of the piston. A guide groove is provided on the outer circumferential surface of the cylinder that rotates around the axis of the cylinder and has a smooth closed curve with an arcuate cross section and one cycle of axial reciprocation per revolution. A plurality of grooves are provided at positions that divide the circumference approximately equally, and the piston has an inner cylindrical surface that holds the rolling ball freely in rotation while restraining its position in the circumferential direction with the rolling ball inserted in each of the guide grooves. The piston is restrained from rotating within the cylinder so that it can slide only in the axial direction, and the central axis of the cylinder is used as an output shaft to pass through the bottom wall of the cylinder to the outside, thereby controlling the rotation of the output shaft. The piston is reciprocated by the piston, and the space formed by the top of the piston, the cylinder head, and the cylinder is used as a combustion chamber, and the space formed by the piston, the bottom of the cylinder, and the cylinder is used as a compression chamber for scavenging air. The present invention is characterized in that a poppet valve is provided at the top of the piston, which is opened by a cam provided at the end of the shaft to open and close communication between the compression chamber and the combustion chamber.

[Operation] When combustion occurs in the fuel chamber, the piston moves downward in a straight line within the cylinder. When the piston descends, its linear motion is converted into rotational motion by the rolling ball and guide groove, and the cylinder rotates in a fixed position.
The rotation is extracted by the output shaft. The exhaust port opens and closes as the piston moves up and down, and a cam attached to the cylinder drives a poppet valve provided at the top of the piston to open and close the scavenging port.

[Example] An embodiment of the invention will be described with reference to FIG.

The axial position of the output shaft 1 is set by a thrust bearing 12 supported by the cylinder bottom 2, so that it can freely rotate around the axis of the cylinder 3.A mounting member 11 is attached to the output shaft 1, and a cylinder 10 is attached to the outside of the output shaft 1. will be established. On the outer circumferential surface of the cylinder 10, guide grooves 9 {9(1) to 9) having an arcuate cross section are provided at positions that are approximately balanced with the circumference (positions that approximately equally divide the circumference).
(6)}. One rolling ball 8, 8'... is fitted to each guide groove, and
Each of the rolling balls 8, 8', . A groove (not shown) is formed in the outer cylindrical part of the piston 5 in the axial direction, and a spherical projection (not shown) that fits into the groove is set at an appropriate position on the inner surface of the cylinder 3 to control the rotation of the piston 5. To prevent. In this way, the piston 5 is structured to be able to slide only in the axial direction along the inner cylindrical surface of the cylinder 3, and is kept airtight with the inner surface of the cylinder 3 by the piston ring 6. formed by a cylinder head 4,
The volume is changed by the movement of the piston 5. A scavenging passage 19 is provided in the mounting member 11 between the compression chamber 13 and the combustion chamber 20, and a scavenging hole 21 that is opened and closed by a poppet valve 22 is provided in the piston top 5'.
Further, the cylinder 3 is provided with an exhaust hole 15 that is opened and closed by a piston 5. A mixture of air and fuel is supplied from the suction port 17, and is sucked into the compression chamber 13 via the reed valve 16 according to the pressure difference.

Since the compression ratio of the scavenging air can be increased and it is easy to attach a mechanical valve drive device to the compression chamber side of the piston 5, a scavenging hole 21 is provided in the piston top 5' as shown in FIG. Scavenging poppet valve 22 whose opening/closing timing can be set arbitrarily rather than point symmetrically
The structure is such that the valve can be opened and closed later than the exhaust, centered after the bottom dead center, by the spring 23, the cam 25, the fixed position guide sleeve 26, and the spring receiver 24 attached to the poppet valve 22.

The guide groove 9 provided on the outer circumferential surface of the cylinder 10 has a plurality of identical waveforms at positions that are approximately balanced with respect to the circumference, as shown in the example in FIG. This is a group of grooves that differ in direction only in phase, for example, in the form of a sine wave or a quadratic curve.
When providing multiple guide grooves, it is possible to avoid crossing the grooves and increase the balance by greatly changing their axial positions, but due to space limitations, it is necessary to avoid crossing each other as shown in the example for miniaturization. arise. By not making the phase difference the same at the intersection of the center lines (chain lines) of each guide groove, it is possible to prevent the rolling balls from entering the intersection at the same time. It is possible to change the phase difference of some of the guide grooves within a range where balance can be maintained.

As the output shaft 1 rotates, the rolling balls 8, 8', etc. receive force from their respective guide grooves, causing the piston 5 to slide back and forth within the cylinder along an axial displacement according to the waveform of the guide grooves. Conversely, it is also possible to generate rotational movement of the output shaft 1 from the reciprocating movement of the piston 5. The piston 5 receives the pressure in the combustion chamber, the pressure in the compression chamber, and the force from the rolling balls, but when the scavenging hole 21 and the exhaust hole 15 are closed in the combustion chamber and the piston 5 rises, reducing the combustion chamber volume, the mixture in the chamber is reduced. The air is compressed and ignited and combusted by the spark plug 18 near the top dead center, increasing the pressure. As the piston 5 descends, the cylinder 10 rotates, converting the work into rotational power of the output shaft 1, and inertia. Output shaft 1 due to force
The piston 5 is raised again by receiving power from the engine to compress the air-fuel mixture. As the piston 5 moves upward, the volume of the air-fuel mixture supplied from the suction port 17 in the scavenging compression chamber 13 increases and the pressure is reduced, so the reed valve 16 opens and flows into the scavenging compression chamber. As the piston 5 descends, the air-fuel mixture is compressed and pressurized in the scavenging air compression chamber, but since the reed valve 16 is a check valve, almost no backflow occurs. As the mounting member 11 rotates, the cam 25 attached to the mounting member 11 pushes up the poppet valve 22, and when the scavenging hole 21 opens, air flows into the combustion chamber in the cylinder according to the pressure difference, and gas exchange is performed.

[Effects of the Invention] According to the present invention, the reciprocating part is limited to only the piston, and not only can it be much smaller and lighter than when it has a normal crank mechanism, but also
The compression ratio of the scavenging air can be increased, and the scavenging air is asymmetrical with respect to the bottom dead center.The high air supply efficiency allows for high output, improved thermal efficiency, and prevention of reverse rotation. In addition, the present invention eliminates the need for scavenging holes provided on both sides of the exhaust hole in the cylinder, as in the chinure scavenging system, and the time from when the exhaust hole opens to when the scavenging hole opens is made sufficiently long so that exhaust gas is sufficiently exhausted before the scavenging is performed. Since it is possible to supply air and scavenge air at asymmetric times centered around bottom dead center, it is possible not only to achieve high air supply efficiency with less blow-through but also to prevent reverse rotation. By setting the scavenging compression ratio to 1.5 or higher, sufficient scavenging can be achieved in a small amount of time and area.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the structure of a small two-stroke gasoline engine according to the present invention, and Fig. 2 is a developed view of guide grooves 9(1) to 9(6) provided on the outer peripheral surface of the cylinder. It is. 1... Output shaft, 3... Cylinder, 4... Cylinder head, 5... Piston, 6... Piston ring, 8, 8'... Rolling ball, 9... Guide groove, 10
...Cylinder, 12...Thrust bearing, 13...Compression chamber, 14...Scavenging hole, 15...Exhaust hole, 16...
Reed valve, 17...Intake port, 18...Spark plug, 19...Scavenging passage, 20...Combustion chamber, 21...
...Scavenging hole, 22...Poppet valve, 23...Spring,
25...cam.

Claims (1)

[Claims] 1 has a cylinder, a piston that fits into the inner surface of the cylinder, and a cylinder that fits into the inner surface of the piston, and the outer circumferential surface of the cylinder that rotates around the axis of the cylinder has an arc-shaped cross section and rotates once per rotation. A plurality of guide grooves configured into smooth closed curves that reciprocate in the axial direction of a period are provided at positions that divide the circumference approximately equally, and the piston is free to rotate the rolling balls with the rolling balls placed in each of the guide grooves. and an inner cylindrical surface that restrains and holds the piston in its position in the circumferential direction, restrains the rotation of the piston within the cylinder so that it can slide only in the axial direction, and the central axis of the cylinder is connected to the output shaft. The piston is reciprocated by the rotation of the output shaft, and the space formed by the top of the piston, the cylinder head, and the cylinder is defined as a combustion chamber, and the piston, the bottom of the cylinder, and the cylinder are A poppet valve is provided at the top of the piston to open and close communication between the compression chamber and the combustion chamber by opening with a cam provided at the shaft end of the cylinder. A two-stroke engine that drives a piston using rolling balls and guide grooves.