JP4133200B2 - Reciprocating engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reciprocating engine.
[0002]
[Prior art]
In a reciprocating engine, in order to reduce sliding friction resistance between a cylinder and a piston, a gas chamber for guiding and storing combustion gas from the combustion chamber is provided between the inner surface of the cylinder and the side surface of the piston facing the inner surface. By forming the gas pressure of the combustion gas in this gas chamber, the piston is lifted from the inner surface of the cylinder against the side pressure in the thrust direction applied to the piston in the combustion stroke, and the inner surface of the cylinder in the reciprocating motion of the piston A technique for reducing the sliding frictional resistance between the piston and the side surface of the piston has been proposed. One example of this proposed reciprocating engine is a first piston ring located adjacent to the upper surface of the piston defining a combustion chamber in which a fuel and air mixture burns, and adjacent to the first piston ring. When the piston is located near the top dead center, the annular space between the second piston ring and the second piston ring is divided into a semi-annular space on the thrust side and a semi-annular space on the anti-thrust side. In some cases, a gas passage is formed in the cylinder side wall to communicate the thrust-side semi-annular space with the combustion chamber.
[0003]
[Patent Document 1]
JP-A-5-26106 [0004]
[Problems to be solved by the invention]
By the way, in a general reciprocating engine, the rotational axis of the crankshaft is not decentered with respect to the center line of the cylinder bore. Therefore, even with the proposed technique, the movement resistance of the piston relative to the cylinder is reduced in the combustion stroke. Is difficult to obtain to the extent that it can be sufficiently satisfied.
[0005]
The present invention has been made in view of the above-described points, and an object of the present invention is to provide a reciprocating engine that can more effectively reduce the reciprocating resistance of the piston with respect to the cylinder.
[0006]
[Means for Solving the Problems]
The reciprocating engine of the first aspect of the present invention is a reciprocating engine in which the rotation center of the crankshaft is offset to the thrust side with respect to the center line of the cylinder bore, and is arranged adjacent to each other in the reciprocating direction of the piston. The space between the first and second piston rings and the first and second piston rings respectively inserted into the first and second ring grooves formed on the side surface of the piston, and the thrust side Partitioning means for dividing the space on the opposite side and the space on the anti-thrust side, and communication means for communicating the space on the thrust side with the combustion chamber.
[0007]
According to the reciprocating engine of the first aspect of the present invention, the reciprocating resistance of the piston with respect to the cylinder can be further effectively reduced by the effect of the offset and the effect of introducing the combustion gas into the thrust side space. Can do.
[0008]
The reciprocating engine according to the second aspect of the present invention is the reciprocating engine according to the first aspect of the present invention, wherein the communication means includes one or a plurality of communication passages provided on the inner surface of the cylinder. Alternatively, the thrust side space is communicated with the combustion chamber via a plurality of communication passages.
[0009]
As described above, one or a plurality of communication passages may be provided. However, in the case of a plurality of communication passages, the combustion gas in the combustion chamber is made to flow on the thrust side by communicating the thrust side space with the combustion chamber through the plurality of communication passages. It can be introduced into the space more quickly and sufficiently.
[0010]
In the reciprocating engine according to the third aspect of the present invention, in the reciprocating engine according to the first or second aspect of the present invention, when the piston is positioned in the vicinity of the top dead center, the communicating means It is designed to communicate with the combustion chamber.
[0011]
The reciprocating engine according to any one of the first to third aspects of the present invention may be a four-cycle engine, a two-cycle engine, or a diesel engine, and any engine suitably exhibits the effects of the present invention. obtain. In the present invention, the communication path may be any form such as a through hole, a groove, or a recess.
[0012]
Next, embodiments of the present invention will be described in more detail based on preferred examples shown in the drawings. The present invention is not limited to these examples.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
1 to 3, a four-cycle reciprocating engine (four-cycle gasoline engine) 1 of this example includes a cylinder 2, a piston 3 that reciprocates within the cylinder 2, and a piston via a piston pin 4 at a small end. 3 is connected adjacent to each other in the reciprocating direction of the piston 3, the connecting rod 5 rotatably connected to the connecting rod 5, the crankshaft 21 rotatably connected to the large end 20 of the connecting rod 5. The piston rings 9 and 10 respectively fitted in a pair of ring grooves formed on the side peripheral surface 6 of the piston 3 and the annular space between the piston rings 9 and 10 are divided into a semi-annular space 12 on the thrust side and A partition means 14 for partitioning into a semi-annular space 13 on the anti-thrust side and a communication means 16 for communicating the space 12 with a combustion chamber 15 in which a mixture of fuel and air is combusted are provided.
[0014]
The cylinder 2 has a cylinder bore (space) 18 defined by an inner surface 17 thereof, and the piston 3 is arranged in the cylinder bore 18 so as to be reciprocally movable. The cylinder 2 is provided with an intake valve 2a and an exhaust valve 2b.
[0015]
In this example, the piston 3 includes an oil ring 19 on the side peripheral surface 6 thereof.
[0016]
The rotation center C of the crankshaft 21 is offset to the thrust side with respect to the center line D of the cylinder bore 18. In this example, as shown in FIG. 2, the rotation center C corresponds to the air-fuel mixture in the combustion chamber 15 before the piston 3 passes the top dead center and is located in the vicinity of the top dead center. When ignition is performed, a line connecting the rotation center E of the connecting rod 5 with respect to the piston pin 4 and the rotation center F of the connecting rod 5 with respect to the crankshaft 21 is inclined with respect to the center line D in the direction opposite to the thrust side. And, as shown in FIG. 3, when the gas pressure in the combustion chamber 15 is maximized while the piston 3 passes through the top dead center and is located in the vicinity of the top dead center, The line connecting the rotation center E and the rotation center F is eccentric to the thrust side with respect to the center line D so as to extend in the same direction as the direction in which the center line D extends. The offset width of the rotation center C with respect to the center line D is preferably in the range of 11 mm to 13 mm, and more preferably in the range of 12 mm to 12.5 mm, but is not limited thereto.
[0017]
The piston ring (top ring or gas ring) 9 is disposed adjacent to the head end surface 23 of the piston 3. The piston ring 9 is preferably arranged so that the joint portion is located closer to the space 12 than the partition member 40. The piston ring 9 is in contact with the inner surface 17 with an elastic force at the outer peripheral surface thereof.
[0018]
The piston ring (second ring or gas ring) 10 is arranged on the side peripheral surface 6 with the piston ring 9 interposed between the head end surface 23 and the piston ring 9. The piston ring 10 is preferably arranged so that the joint portion is located closer to the space 13 than the partition member 40. The piston ring 10 is in contact with the inner surface 17 with an elastic force at the outer peripheral surface thereof.
[0019]
The partition means 14 is provided between the piston rings 9 and 10, and includes a pair of partition members 40 disposed to face each other in the axial direction of the piston pin 4.
[0020]
The communication means 16 includes a communication passage 70 provided in the inner surface 17 on the thrust side of the cylinder 2, and the communication passage 70 allows the space 12 to pass through the combustion chamber 15 when the piston 3 is positioned near the top dead center. It is arranged to communicate with. In this example, the communication path 70 is defined by a concave surface 71 formed on the inner surface 17 of the cylinder 2.
[0021]
According to the communication means 16, when the piston 3 is positioned near the top dead center, the communication path 70 allows the space 12 to communicate with the combustion chamber 15, so that the combustion gas in the combustion chamber 15 is introduced. Therefore, a counter-pressure B in the anti-thrust direction against the thrust A in the thrust direction applied to the piston 3 in the combustion stroke can be applied to the piston 3, and thus the piston 3 Can be gas floated.
[0022]
Hereinafter, the operation of the reciprocating engine 1 of the present example will be described. In the combustion stroke of the mixture of fuel and air that is started after the end of the compression stroke, as shown in FIG. The air-fuel mixture in the combustion chamber 15 is ignited before passing and near the top dead center, and the thrust-side space 12 is communicated with the combustion chamber 15 through the communication passage 70 to the thrust-side space 12. Combustion gas was introduced, and as shown in FIG. 3, the gas pressure of the combustion gas increased and increased to the maximum while the piston 3 was located near the top dead center after passing through the top dead center of the piston 3. The piston 3 receives the gas pressure and accelerates toward the bottom dead center.
[0023]
According to the reciprocating engine 1 of the present example, the rotation center C of the crankshaft 21 is offset to the thrust side with respect to the center line D of the cylinder bore 18, whereby in this example, the piston 3 is the piston 3. When the gas pressure of the combustion gas increases to the maximum while passing through the top dead center and in the vicinity of the top dead center, the direction in which the line connecting the rotation centers E and F extends in the center line D Therefore, the thrust side pressure A applied to the piston 3 is greatly reduced based on the gas pressure in the combustion chamber 15 and the space 12 is sufficiently resisted against the side pressure A. The reciprocating engine 1 of the present example is as described above as a result of the gas pressure of the introduced combustion gas being applied to the piston 3 so that the anti-thrust pressure B directed to the anti-thrust side can be suitably floated. In During combustion stroke, it is possible to significantly reduce the sliding frictional resistance in the thrust side between the piston rings 9 and 10 and the inner surface 17 of the cylinder 2 that occurs on the basis of the side pressure A.
[0024]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the reciprocation engine which can obtain more effectively reduction of the reciprocation resistance of the piston with respect to a cylinder can be provided.
[Brief description of the drawings]
FIG. 1 is an explanatory front view of an example of an embodiment of the present invention.
FIG. 2 is an operation explanatory diagram of the example shown in FIG. 1;
FIG. 3 is an operation explanatory diagram of the example shown in FIG. 1;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Reciprocating engine 2 Cylinder 3 Piston 4 Piston pin 5 Connecting rod 6 Side peripheral surface 9, 10 Piston ring 12, 13 Space 14 Compartment means 15 Combustion chamber 16 Communication means 18 Cylinder bore 20 Large end part 21 Crankshaft

Claims (3)

  A reciprocating engine in which the rotation center of the crankshaft is offset to the thrust side with respect to the center line of the cylinder bore, and is disposed adjacent to each other in the reciprocating direction of the piston, and is formed on a side surface of the piston. A crankshaft comprising first and second piston rings fitted in the first and second ring grooves, respectively, and communication means for communicating a space between the first and second piston rings to the combustion chamber. When the ignition of the air-fuel mixture in the combustion chamber is performed before the piston passes through the top dead center and near the top dead center, the rotation of the connecting rod with respect to the piston pin is performed. The line connecting the center of movement and the center of rotation of the connecting rod relative to the crankshaft is inclined to the opposite side of the cylinder bore, and the piston passes through the top dead center. When the gas pressure in the combustion chamber rises to the maximum while it is located near the top dead center, a line connecting the pivot center with respect to the piston pin and the pivot center with respect to the crankshaft of the connecting rod A reciprocating engine that is eccentric to the thrust side with respect to the center line so that is extended in the same direction as the direction in which the center line of the cylinder bore extends.   The communication means includes one or a plurality of communication passages provided on the inner surface of the cylinder, and the thrust side space is communicated with the combustion chamber through the one or more communication passages. The reciprocating engine described in 1.   The reciprocating engine according to claim 1 or 2, wherein the communication means is configured to communicate the thrust side space with the combustion chamber when the piston is positioned near the top dead center.

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