JP2020029803A - Opposing piston engine - Google Patents

Abstract

To homogeneously propagate a flame after ignition into a combustion chamber as a whole.SOLUTION: A pair of pistons (3, 4) are arranged in one cylinder (2), and the pistons (3, 4) are reciprocated to each other in an opposite direction while facing each other at their apexes. A combustion chamber (16) is formed of recessed grooves (11, 12) formed at the apexes of both the pistons (3, 4), and a recessed groove (13) formed in a cylinder block (1). A cross section shape of the combustion chamber (16) at a cut face including an axial line of the cylinder (2) when both the pistons (3, 4) are located at top dead points is formed into a protrusive lens shape. A pair of exhaust valves (19) are arranged on an inner wall face (15) of the cylinder block (1) which defines the recessed groove (13) with an interval in a circumferential direction of the cylinder (2), and an ignition plug (21) is arranged on the inner wall face (15) of the cylinder block (1) surrounded by the pair of the exhaust valves (19) and external peripheral edge of the cylinder (2).SELECTED DRAWING: Figure 1

Description

  The present invention relates to opposed piston engines.

  In a single cylinder, a pair of pistons are reciprocated in opposite directions while the top surfaces of the pistons face each other, and a flat top surface region is formed on each side of each piston top surface facing each other. On the other side of each piston top surface facing each other, a concave groove is formed which gradually becomes deeper as the distance from the flat top surface region is increased. When both pistons are located at the top dead center, the concave grooves of both pistons are formed. A groove aligned with the groove is formed in the cylinder block, and the groove formed in the cylinder block is defined by inner wall surfaces of the cylinder block facing each other at an interval in the axial direction of the cylinder. The combustion chamber is formed by the grooves of both pistons and the groove of the cylinder block, and the opposed valves in which the intake valve, the exhaust valve, and the ignition plug are arranged Ton engine are known (e.g., see Patent Document 1).

JP-A-2017-193994

  However, in this opposed-piston engine, the flame spread after ignition is non-uniform due to the fact that the spark plug is located deep inside the concave groove of the cylinder block and the cross section of the combustion chamber is distorted. The time required for combustion becomes longer, and knocking is more likely to occur. As a result, there is a problem that the thermal efficiency does not become sufficiently high and a sufficiently high output cannot be obtained.

  To solve the above problem, according to the present invention, a pair of pistons are reciprocated in opposite directions in a single cylinder while the top surfaces of the pistons face each other. A flat top surface area that forms a squish area is formed on one facing side, and a concave groove that gradually becomes deeper as the distance from the flat top surface area is formed on the other side of each piston top face that faces each other. A groove is formed in the cylinder block that is aligned with the groove of both pistons when both pistons are located at the top dead center.A groove formed in the cylinder block is formed in the cylinder block. The combustion chamber is defined by the inner wall surfaces of the cylinder block facing each other at an interval in the axial direction, and the groove of both pistons and the groove of the cylinder block form. In an opposed-piston engine in which an intake valve, an exhaust valve, and an ignition plug are arranged in a concave groove of a cylinder block, the cross-sectional shape of a combustion chamber at a cut surface including an axis of a cylinder when both pistons are located at a top dead center is shown. A pair of exhaust valves are arranged on the inner wall surface of the cylinder block, which has a convex lens shape and defines a concave groove, at intervals in the circumferential direction of the cylinder. There is provided an opposed-piston engine in which a spark plug is disposed on an inner wall surface of a cylinder block surrounded by an outer peripheral edge.

  By arranging the ignition plug in the center of the combustion chamber and making the cross-sectional shape of the combustion chamber symmetrical with respect to the ignition plug, flame propagation after ignition becomes uniform and the time required for combustion becomes longer. As a result, high thermal efficiency and high output can be obtained while preventing occurrence of knocking.

FIG. 1 is a side sectional view of an opposed piston engine. 2A and 2B are views showing the combustion chamber taken along the line AA and the line BB of FIG. 1, respectively.

  FIG. 1 is a side sectional view of an embodiment of an opposed piston engine according to the present invention. Referring to FIG. 1, 1 is a cylinder block of the engine body, 2 is a cylinder formed in the cylinder block, 3 and 4 are a pair of pistons arranged in the cylinder 2, and 5 is a piston through a connecting rod 6. A crankshaft 7 connected to 3 denotes a crankshaft connected to the piston 4 via a connecting rod 8, respectively. The crankshaft 5 and the crankshaft 7 are connected via, for example, a gear mechanism such that the top surfaces of the pistons 3 and 4 reciprocate in opposite directions while facing each other.

  FIG. 1 shows a case where each of the pistons 3 and 4 is at the top dead center position. As shown in FIG. 1, FIG. 2A and FIG. 2B, flat top surfaces 9 and 10 are formed on one of the top surfaces of the pistons 3 and 4 facing each other, respectively. On the other side of the top surfaces 3 and 4 facing each other, concave grooves 11 and 12 are formed, which gradually become deeper as the distance from the corresponding flat top surface regions 9 and 10 increases. The flat top regions 9 and 10 of the pistons 3 and 4 occupy almost half of the top surfaces of the pistons 3 and 4, and when the pistons 3 and 4 are located at the top dead center, these flat top regions 9 and 10 are formed. , 10 are formed.

  On the other hand, as shown in FIG. 1, a groove 13 is formed in the cylinder block 1 so as to be aligned with the grooves 11, 12 of the pistons 3 and 4 when the pistons 3 and 4 are located at the top dead center. . A concave groove 13 formed in the cylinder block 1 is defined by inner wall surfaces 14, 15 of the cylinder block 1 facing each other at an interval in the axial direction of the cylinder 2. A combustion chamber 16 is formed by the grooves 11 and 12 and the concave groove 13 of the cylinder block 1. As shown in FIG. 1, when the pistons 3 and 4 are located at the top dead center, the cross-sectional shape of the combustion chamber 16 on the cut surface including the axis of the cylinder 2 has a convex lens shape.

  As shown in FIGS. 1 and 2A, a pair of intake valves 17 are provided on one inner wall surface 14 of the cylinder block 1 defining the concave groove 13 at intervals in the circumferential direction of the cylinder 2. An air-fuel mixture is supplied into the combustion chamber 16 from the intake port 18 via the intake valves 17. On the other hand, as shown in FIGS. 1 and 2B, a pair of exhaust valves is provided on the other inner wall surface 15 of the cylinder block 1 defining the concave groove 13 at intervals in the circumferential direction of the cylinder 2. A burned gas in the combustion chamber 16 is discharged to an exhaust port 20 through these exhaust valves 19. An ignition plug 21 is disposed on the inner wall surface 15 of the cylinder block 1 surrounded by the pair of exhaust valves 19 and the outer peripheral edge 2a of the cylinder 2. As can be seen from FIG. 2B, the ignition plug 21 is disposed at the center of the combustion chamber 16 formed by the grooves 11, 12 and 13.

  The engine shown in FIG. 1 is a four-cycle engine. When the air-fuel mixture in the combustion chamber 16 is ignited by the ignition plug 21, the expansion stroke is started, and the pistons 3, 4 move away from each other. Next, when the exhaust stroke is started, the pistons 3 and 4 move closer to each other, and the burned gas in the combustion chamber 16 is discharged into the exhaust port 20 via the exhaust valve 19. Next, when the intake stroke is started, the pistons 3 and 4 move away from each other, and the air-fuel mixture is sucked into the combustion chamber 16 from the intake port 18 via the intake valve 17. Next, a compression stroke is started, and when the pistons 3 and 4 approach the top dead center, a squish flow is injected into the combustion chamber 16 from a squish area formed between the flat top surfaces 9 and 10 of the pistons 3 and 4. I do. Due to this squish flow, combustion of the air-fuel mixture in the combustion chamber 16 is promoted.

  As described above, according to the present invention, the pair of pistons 3 and 4 are reciprocated in opposite directions in the single cylinder 2 while the top surfaces of the pistons 3 and 4 face each other. Flat top surfaces 9 and 10 forming squish areas are formed on one of the top surfaces facing each other and flat flat surfaces are formed on the other facing sides of the top surfaces of the pistons 3 and 4, respectively. Concave grooves 11 and 12 are formed which gradually become deeper as the distance from the regions 9 and 10 increases. When both pistons 3 and 4 are located at the top dead center, concave grooves 13 are formed in cylinder block 1 to be aligned with concave grooves 11 and 12 of both pistons 3 and 4, and are formed in cylinder block 1. The concave groove 13 is defined by inner wall surfaces 14 and 15 of the cylinder block 1 that face each other at an interval in the axial direction of the cylinder 2. A combustion chamber 16 is formed by the grooves 11 and 12 of the pistons 3 and 4 and the groove 13 of the cylinder block 1, and an intake valve 17, an exhaust valve 19, and an ignition plug 21 are formed in the groove 13 of the cylinder block 1. Be placed. When the pistons 3 and 4 are located at the top dead center, the cross-sectional shape of the combustion chamber 16 in a section including the axis of the cylinder 2 is a convex lens. A pair of exhaust valves 19 are arranged on the inner wall surface 15 of the cylinder block 1 defining the concave groove 13 at intervals in the circumferential direction of the cylinder 2. An ignition plug is arranged on the inner wall surface 15 of the cylinder block 1 surrounded by the outer peripheral edge 2a.

  As described above, in the present invention, the cross-sectional shape of the combustion chamber 16 on the cut surface including the axis of the cylinder 2 when both the pistons 3 and 4 are located at the top dead center has a convex lens shape. An ignition plug 21 is arranged at the center of the thickness. That is, the ignition plug 21 is disposed at the center of the combustion chamber 16, and the sectional shape of the combustion chamber 13 is formed symmetrically with respect to the ignition plug 21 as can be seen from FIG. 1. As described above, if the ignition plug 21 is disposed at the center of the combustion chamber 16 and the sectional shape of the combustion chamber 13 is formed symmetrically with respect to the ignition plug 21, The flame propagates uniformly throughout the combustion chamber 16 and the time required for combustion is reduced. As a result, high thermal efficiency and high output can be obtained while preventing the occurrence of knocking.

DESCRIPTION OF SYMBOLS 1 Cylinder block 2, Cylinder 3, 4 Piston 5, 7 Crankshaft 11, 12, 13 Concave groove 16 Combustion chamber 17 Intake valve 19 Exhaust valve 21 Ignition plug

Claims (1)

  In a single cylinder, a pair of pistons are reciprocated in opposite directions while the top surfaces of the pistons face each other, and a flat surface that forms a squish area on each of the facing sides of each piston top surface. When the top surface area is formed and on the other side of each piston top surface facing each other, a concave groove is formed which gradually becomes deeper as the distance from the flat top surface area increases, and when both pistons are located at the top dead center. A groove is formed in the cylinder block, the groove being aligned with the grooves of both pistons, and the grooves formed in the cylinder block are formed in the cylinder block facing each other at an interval in the axial direction of the cylinder. The combustion chamber is defined by the groove of both pistons and the groove of the cylinder block, and an intake valve and an exhaust valve are formed in the groove of the cylinder block. In the opposed-piston engine in which the ignition plugs are arranged, the cross-sectional shape of the combustion chamber at the cross-section including the axis of the cylinder when both pistons are located at the top dead center has a convex lens shape, and defines a concave groove. A pair of exhaust valves are arranged on the inner wall surface of the block at intervals in the circumferential direction of the cylinder, and a spark plug is provided on the inner wall surface of the cylinder block surrounded by the pair of exhaust valves and the outer peripheral edge of the cylinder. With an opposed piston engine.

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