JP6989318B2 - engine - Google Patents

Description

The present invention relates to an engine in which a piston reciprocates in a cylinder.

For example, in the case of a four-cycle gasoline engine of an automobile, a suction stroke for sucking an air-fuel mixture (air containing fuel) into the cylinder and a compression stroke for compressing the air-fuel mixture while the piston reciprocates twice in the cylinder. There are four strokes, a combustion stroke in which the compressed air-fuel mixture is ignited to burn the air-fuel mixture, and an exhaust stroke in which the combustion gas is exhausted. In the suction stroke and the combustion stroke among these four strokes, the piston moves from the top dead center side to the bottom dead center side. During the movement of the piston to the bottom dead center side, gas (for example, air) exists on the back side (crankshaft side) of the piston, so that the gas pushed out from the cylinder as the piston moves is cranked. Enter the case. At this time, this gas acts as a resistance to the movement of the piston toward the bottom dead center side, and a pumping loss occurs. The cause of this pumping loss is, for example, a small volume inside the crankcase and a narrow gas flow path on the back side of the piston.

A technique for reducing the pumping loss on the back side of this piston has been proposed. For example, in Patent Document 1, a cylinder block in which a plurality of cylinders are formed and a crankcase fastened and fixed to the cylinder block provide a plurality of partition walls for supporting a crankshaft to form each crank chamber corresponding to each cylinder. A multi-cylinder internal combustion engine formed to partition is disclosed. In this multi-cylinder internal combustion engine, a communication hole for communicating each pair of adjacent crank chambers adjacent to each other with the partition wall interposed therebetween is formed in a plurality of partition walls. This communication hole allows the movement of gas between adjacent crank chambers when the piston moves in the opposite direction between adjacent cylinders.

Japanese Unexamined Patent Publication No. 2010-180747

As described above, according to the technique disclosed in Patent Document 1, since a communication hole is formed between adjacent crank chambers in the crankcase, bottom dead center occurs during the suction stroke or combustion stroke of any cylinder. After the gas on the back side of the piston moving to the point side enters the crankcase from the cylinder, the gas entering the crankcase can move to the adjacent crankcase through the communication hole. However, in order for the gas to move through the communication hole, it is necessary for the gas to enter the crank chamber from the cylinder, and the diameter of the communication hole cannot be sufficiently taken from the viewpoint of block strength, for example. In that case, the pumping loss on the back side of the piston may not be sufficiently reduced.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an engine capable of sufficiently reducing the pumping loss on the back surface side of the piston.

The engine according to the present invention includes a cylinder block provided with a plurality of cylinders, a piston reciprocally housed in the cylinders, a piston ring attached to the pistons, and a crankshaft connected to the pistons. An opening is formed on the peripheral wall of the cylinder to be opened on the crankshaft side and on the other cylinder side adjacent to the cylinder from the position of the pistring when the piston is located at the bottom dead point in the cylinder. The cylinder block is characterized in that a communication passage is formed in which an opening of one adjacent cylinder among a plurality of cylinders and an opening of another cylinder are communicated with each other.

In the engine according to the present invention, an opening is formed in the peripheral wall of each cylinder, and this opening is opened on the adjacent cylinder side and on the crankshaft side with respect to the piston ring. Further, in the engine according to the present invention, a communication passage that communicates between the openings of adjacent cylinders is formed in the cylinder block. The back side (crankshaft side) of the cylinder in one adjacent cylinder and the back side of the other cylinder are communicated with each other through the opening of each cylinder and the communication passage of the cylinder block. As a result, for example, when the piston in one cylinder is moving from the top dead center side to the bottom dead center side, the gas existing on the back side of this one piston is transferred to the back surface of the pistons of the adjacent other cylinders. Can be moved to the side. In particular, since the opening is opened on the crankshaft side of the piston ring, the piston ring can slide with respect to the peripheral wall of the cylinder, and the opening is within the possible range without impairing the function of the piston ring. Can be increased, and the amount of gas transferred between the cylinders can be increased. As a result, the amount of gas that enters the crankcase among the gas that is pushed out from the cylinder by the piston that moves to the bottom dead center side is reduced. Therefore, the resistance to the movement of the piston toward the bottom dead center side can be reduced. As described above, according to the engine according to the present invention, it is possible to sufficiently reduce the pumping loss on the back surface side of the piston.

The engine according to the present invention preferably includes a cylinder liner provided in the cylinder block, and the opening is preferably formed in the cylinder liner. With this configuration, the back side of one adjacent cylinder and the back side of another cylinder can be connected by a communication passage that communicates between the openings formed in each cylinder liner and the openings of adjacent cylinder liners. Can be communicated.

In the engine according to the present invention, the piston has a piston body to which a piston ring is mounted and a piston skirt provided on the crank shaft side of the piston body, and the opening is such that the piston dies downward in the cylinder. It is preferably formed along the shape of the notch between the pair of facing skirts of the piston skirt when it is located at a point. By forming an opening (and thus a continuous passage) along the shape of the notch in the piston skirt in this way, the pair of facing skirts of the piston skirt can slide with respect to the peripheral wall of the cylinder. The opening can be increased to the extent possible without impairing the function of the piston skirt. It should be noted that the larger the opening and the continuous passage of the cylinder block, the lighter the engine can be.

In the engine according to the present invention, the communication passage is the other cylinder when the piston in one cylinder among the adjacent cylinders among the plurality of cylinders and the other cylinders is moving toward the bottom dead point side. It is preferable that the inner piston is formed between one cylinder and the other cylinder of the combination in which the inner piston moves toward the top dead point side. For example, when one piston is moving to the bottom dead center side and the other piston next to it is moving to the top dead center side, one in the larger space on the back side of the piston in the other cylinder. The gas on the back side of the piston in the cylinder can be moved. Further, in other cylinders in which the piston moves to the top dead center side, gas enters the back surface side of the piston, and this gas can assist the movement of the piston to the top dead center side.

According to the present invention, it is possible to sufficiently reduce the pumping loss on the back surface side of the piston.

It is sectional drawing which shows the schematic structure of the engine which concerns on embodiment. FIG. 3 is a cross-sectional view taken along the line II-II of FIG. It is a perspective view of the cylinder liner shown in FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the figure, the same reference numerals are used for the same or corresponding parts. Further, in each figure, the same elements are designated by the same reference numerals, and duplicate description will be omitted.

In the embodiment, the engine according to the present invention is applied to a horizontally opposed 4-cylinder gasoline engine mounted on an automobile. The engine 1 according to the embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view showing a schematic configuration of the engine 1 according to the embodiment. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. Note that FIGS. 1 and 2 show a part of the engine 1 (a part of the cylinder block), and other parts such as a cylinder head and an oil pan are omitted. Further, in the cross-sectional views of FIGS. 1 and 2, the cylinder block and the cylinder liner are shown in cross section, but some parts (piston and the like) are shown in appearance.

The engine 1 includes a cylinder block 2. Cylinder heads (not shown) provided with intake valves, exhaust valves, etc. are attached to one end and the other end of the cylinder block 2 in the vehicle width direction D1 (left-right direction of the automobile). .. Each of these valves is opened and closed by a valve operating mechanism (not shown) including a camshaft having a plurality of cams. An oil pan (not shown) for storing engine oil is attached to the lower end of the cylinder block 2.

The cylinder block 2 is formed with a crankcase 2a at the center in the vehicle width direction D1. The crankshaft 3 is rotatably supported by the crankcase 2a. The crankshaft 3 includes, for example, five crank journals 3a, four crank pins 3b, eight balance weights 3c, and eight crank arms 3d. The crank journal 3a is the center of rotation of the crankshaft 3. The crank pin 3b is eccentric from the rotation center axis A of the crankshaft 3 (crank journal 3a) and is arranged alternately with the crank journal 3a. The balance weight 3c is integrally formed with the crank arm 3d and is arranged on the opposite phase side of the crank pin 3b. The crank arm 3d is arranged between the adjacent crank journal 3a and the crank pin 3b, and connects the crank journal 3a and the crank pin 3b.

In the cylinder block 2, two cylinder hole portions 2b and 2c are formed on one side of the crankcase 2a in the vehicle width direction D1, and two cylinder hole portions 2d and 2e are formed on the other side. ing. The cylinder hole 2b and the cylinder hole 2c are arranged in parallel at predetermined intervals in the front-rear direction D2 of the automobile orthogonal to the vehicle width direction D1. The cylinder hole portion 2d and the cylinder hole portion 2e are arranged in parallel with a predetermined interval in the front-rear direction D2.

The cylinder hole portions 2b, 2c, 2d, 2e extend from the end portion of the cylinder block 2 in the vehicle width direction D1 to the crankcase 2a, and have a substantially circular cross-sectional shape. One end of the cylinder hole 2b, 2c, 2d, 2e is open, and the cylinder head described above is arranged. The other ends of the cylinder holes 2b, 2c, 2d, and 2e are communicated with the crankcase 2a.

Hollow cylindrical cylinder liners 4A, 4B, 4C, and 4D are fitted and fixed to the cylinder holes 2b, 2c, 2d, and 2e of the cylinder block 2, respectively. With this configuration, the cylinder block 2 is provided with cylinders (cylinders) 5A, 5B, 5C, and 5D. The peripheral wall 4a of each cylinder liner 4A, 4B, 4C, 4D becomes the peripheral wall (sliding surface) of each cylinder 5A, 5B, 5C, 5D.

Pistons 6A, 6B, 6C, and 6D are housed in the cylinders 5A, 5B, 5C, and 5D so as to be reciprocating. The pistons 6A, 6B, 6C, and 6D have a piston body 6a and a piston skirt 6b formed on the crankshaft 3 side of the piston body 6a. The piston body 6a is formed in a substantially cylindrical shape. For example, three annular piston ring grooves are provided on the outer peripheral surface of the piston body 6a, and the piston rings 6c, 6d, and 6e are mounted on the respective piston ring grooves. The outer diameter of the piston rings 6c, 6d, 6e is slightly larger than the outer diameter of the piston body 6a, and is in contact with the peripheral walls 4a of the cylinder liners 4A, 4B, 4C, 4D.

The piston ring 6c on the cylinder head side (camshaft side) is called a top ring and is a compression ring. The intermediate piston ring 6d is called a second ring and is a compression ring. The compression ring has functions such as prevention of gas leakage from the combustion chamber. The piston ring 6e on the crankshaft 3 side is an oil ring. The oil ring has functions such as scraping off excess engine oil and preventing engine oil from entering the combustion chamber.

The piston skirt 6b has a function of suppressing the swing of the pistons 6A, 6B, 6C, 6D that reciprocate in the cylinders 5A, 5B, 5C, 5D. The piston skirt 6b has a pair of skirt portions 6f and 6f facing each other with a piston pin (not shown) interposed therebetween. The skirt portion 6f extends from the piston body 6a to the crankshaft 3 side. The piston skirt 6b is formed with a pair of notched portions 6g and 6g facing each other between one skirt portion 6f and the other skirt portion 6f. The shape of the notch portion 6g corresponds to the shape of the facing skirt portions 6f, 6f.

One ends of the connecting rods 7A, 7B, 7C, and 7D are rotatably attached to each of the pistons 6A, 6B, 6C, and 6D by a piston pin. The other ends of the connecting rods 7A, 7B, 7C, and 7D are rotatably attached to the crankpins 3b held between the crank arms 3d and 3d. In the engine 1, the reciprocating motion (linear motion) of the pistons 6A, 6B, 6C, 6D in the cylinders 5A, 5B, 5C, 5D is converted into rotary motion via the connecting rods 7A, 7B, 7C, 7D. , Rotate the crankshaft 3. While the pistons 6A, 6B, 6C, and 6D reciprocate twice (the crankshaft 3 makes two revolutions), the four strokes (4 strokes) of the intake stroke, compression stroke, combustion stroke, and exhaust stroke, which are one cycle of the engine 1. Is done.

In the suction stroke and the combustion stroke among these four strokes, the pistons 6A, 6B, 6C, and 6D move from the top dead center side to the bottom dead center side. At this time, with respect to the movement of the pistons 6A, 6B, 6C, 6D to the bottom dead center side, the back side (crankshaft 3 side) of the pistons 6A, 6B, 6C, 6D in the cylinders 5A, 5B, 5C, 5D. The gas present in (for example, air) becomes a resistance. When this resistance becomes large, the pumping loss on the back side of the pistons 6A, 6B, 6C, 6D becomes large, and the fuel consumption is deteriorated.

Therefore, in order to reduce the pumping loss on the back side of the pistons 6A, 6B, 6C, 6D, the engine 1 is located between the adjacent cylinders 5A and 5B and between the cylinders 5C and 5D in the front-rear direction D2. It has a structure that allows the movement of gas on the back side of the cylinder. Therefore, in the engine 1, openings 4b are formed in the cylinder liners 4A, 4B, 4C, and 4D, respectively, and communication passages (communication holes) 2g and 2h are formed in the cylinder block 2.

The opening 4b of the cylinder liners 4A, 4B, 4C, and 4D will be described with reference to FIG. Hereinafter, the opening 4b of the cylinder liner 4A will be described, but since the openings 4b of the other cylinder liners 4B, 4C, and 4D are the same, the description thereof will be omitted. FIG. 3 shows a perspective view of the cylinder liner 4A. FIG. 3 shows the appearance of the piston 6A when it is located at the bottom dead center in the cylinder 5A (cylinder liner 4A) in addition to the cylinder liner 4A by a two-dot chain line.

On the crankshaft 3 side of the cylinder liner 4A, a pair of facing openings 4b and 4b are formed corresponding to the positions of the pair of notches 6g and 6g facing each other in the piston skirt 6b of the piston 6A in the circumferential direction. ing. One of the pair of openings 4b and 4b in the cylinder liner 4A is opened on the side of the adjacent cylinder liner 4B in the front-rear direction D2, and the other opening 4b is opened on the opposite side of the cylinder liner 4B. ing.

The opening 4b is opened in a substantially concave shape on the crankshaft 3 side of the cylinder liner 4A. In particular, the opening 4b is formed (opening) along the shape of the notch 6g (the portion that does not slide with respect to the peripheral wall 4a of the cylinder liner 4A) of the piston skirt 6b when the piston 6A is located at the bottom dead center. ) Has been. Therefore, the shape of the opening 4b corresponds to the shape of the notch 6g of the piston skirt 6b. By providing such openings 4b and 4b, a part of the hollow cylindrical cylinder liner 4A is chipped, but when the piston 6A reciprocates in the cylinder 5A, the skirt portion 6f of the piston skirt 6b , 6f and the piston rings 6c, 6d, 6e can be slid with respect to the peripheral wall 4a of the cylinder liner 4A. The cylinder hole 2b is formed with a step along the shape of the openings 4b and 4b formed in the cylinder liner 4A.

In the example shown in FIG. 3 and the like, the cylinder liner 4A is provided with a pair of openings 4b and 4b corresponding to the pair of notches 6g and 6g of the piston skirt 6b, but the cylinder liners adjacent to each other in the front-rear direction D2. The opening 4b may be provided only on the 4B side. That is, the configuration may be such that the opening 4b on the opposite side of the cylinder liner 4B is not provided.

The communication passages 2g and 2h will be described. In the cylinder block 2, a communication passage 2g is formed between the adjacent cylinders 5A and the cylinder 5B in the front-rear direction D2, and a communication passage 2h is formed between the adjacent cylinders 5C and the cylinder 5D in the front-rear direction D2. There is.

The communication passage 2g is formed so as to communicate the opening 4b of the opposing cylinder liner 4A and the opening 4b of the cylinder liner 4B. The communication passage 2h is formed so as to communicate the opening 4b of the opposing cylinder liner 4C and the opening 4b of the cylinder liner 4D. The cross-sectional shape of the communication passages 2g and 2h corresponds to the shape of the opening 4b.

The operation of the opening 4b provided in the engine 1 and the communication passages 2g and 2h in this way will be described. Hereinafter, the operation between the adjacent cylinders 5A and 5B (between the pistons 6A and 6B) on one side in the vehicle width direction D1 will be described as an example, but the operation between the adjacent cylinders 5C and 5D (between the pistons 6A and 6B) on the other side in the vehicle width direction D1 will be described. The same effect is obtained between 6C and 6D).

The opening 4b and the opening 4b of the cylinder liner 4B formed in the facing cylinder liner 4A and the communication passage 2g formed in the cylinder block 2 together with the back surface side (crankshaft 3 side) of the piston 6A in the cylinder 5A. It communicates with the back surface side of the piston 6B in the cylinder 5B. Further, the pistons 6A and 6B adjacent to each other in the front-rear direction D2 move in opposite directions when they are reciprocating (while the engine 1 is in operation).

For example, when the piston 6A moves from the top dead center side to the bottom dead center side (suction stroke, combustion stroke), the piston 6B moves from the bottom dead center side to the top dead center side (compression stroke, exhaust stroke). ), When the piston 6A reaches the bottom dead center, the piston 6B reaches the top dead center. During the movement of the piston 6A to the bottom dead center side, the space on the back surface side of the piston 6A in the cylinder 5A becomes smaller, and the gas (for example, air) on the back surface side of the piston 6A in the cylinder 5A is pressed. This pressed gas (gas extruded from the inside of the cylinder 5A) flows to the cylinder 5B side through the openings 4b and 4b of the cylinder liners 4A and 4B and the communication passage 2g, and the back surface of the piston 6B in the cylinder 5B. It flows into the space on the side. At this time, since the piston 6B is moving toward the top dead center side, the space on the back surface side of the piston 6B in the cylinder 5B becomes large.

Since the openings 4b and the communication passages 2g of the cylinder liners 4A and 4B are formed according to the shape of the notch 6g of the piston skirt 6b, the cross-sectional area of the gas flow path between the cylinders 5A and the cylinder 5B is large. It is large and the flow rate of the gas flowing from the cylinder 5A to the cylinder 5B is large. Therefore, of the gas pressed by the piston 6A and pushed out from the inside of the cylinder 5A (gas on the back surface side of the piston 6A), the amount of gas flowing into the crankcase 2a from the cylinder 5A is small. Therefore, for example, even when the volume of the crankcase 2a is small, the resistance to the movement of the piston 6A to the bottom dead center side by the gas on the back surface side of the piston 6A is reduced. Similarly, when the piston 6B moves from the top dead center side to the bottom dead center side, the resistance to the movement of the piston 6B to the bottom dead center side by the gas on the back surface side of the piston 6B is reduced.

As described above, the cylinder liners 4A and 4B, which are the sliding surfaces of the cylinders 5A and 5B, have openings 4b, but the skirts of the piston skirts 6b of the reciprocating pistons 6A and 6B. The 6f, 6f and the piston rings 6c, 6d, 6e can be slid with respect to the peripheral wall 4a of each of the cylinder liners 4A, 4B. Therefore, during the reciprocating motion of the pistons 6A and 6B, the functions of the piston skirt 6b and the functions of the piston rings 6c, 6d and 6e described above are not impaired.

According to the engine 1 according to the embodiment, the cylinders 5A, 5B and the cylinders 5C, 5D are communicated with each other by the opening 4b of each cylinder liner 4A, 4B, 4C, 4D and the communication passages 2g, 2h of the cylinder block 2. As a result, the pumping loss on the back surface side of the pistons 6A, 6B, 6C, 6D can be sufficiently reduced. By reducing this pumping loss, it is possible to improve the fuel efficiency of the automobile on which the engine 1 is mounted.

According to the engine 1 according to the embodiment, since the openings 4b (communication passages 2g, 2h) are formed to match the shape of the notch 6g of the piston skirt 6b, the piston skirt 6b and the piston rings 6c, 6d, 6e The opening 4b (and thus the communication passage 2g, 2h) can be increased without impairing the function of the above, and the amount of gas movement (flow rate) between the cylinders 5A and 5B and between the cylinders 5C and 5D can be increased. .. The larger the opening 4b and the communication passages 2g and 2h, the lighter the weight of the engine 1.

According to the engine 1 according to the embodiment, the cylinders 5A and 5B and the cylinders 5C and 5D that move in opposite directions are communicated with each other by the openings 4b and 4b and the communication passages 2g and 2h, respectively. When the piston in the cylinder is moving to the bottom dead point side and the piston in the other adjacent cylinder is moving to the top dead point side, in the larger space on the back side of the piston in the other cylinder. The gas on the back side of the piston in one cylinder can be moved. Further, on the other cylinder side where the piston moves to the top dead center side, gas enters the back surface side of the piston, and this gas can assist the movement of the piston to the top dead center side. As a result, the fuel efficiency of the automobile on which the engine 1 is mounted can be further improved.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and can be modified in various ways. For example, in the above embodiment, it is applied to the horizontally opposed 4-cylinder gasoline engine 1, but it is also applied to other types of engines such as other cylinder arrangements such as in-line type and V type, and other cylinder numbers such as 6 cylinders. It is possible. For example, when applied to a series-type engine, when one adjacent cylinder among a plurality of cylinders arranged in series moves to the top dead center side, the other cylinder moves to the bottom dead center side (). That is, it is preferable to form a communication path only between the cylinders of the combination (moving in the opposite direction). For example, in the case of an in-line 4-cylinder gasoline engine, in the first to fourth cylinders arranged in series, between the first cylinder and the second cylinder, and between the third cylinder and the fourth cylinder. It is advisable to form a continuous passage between them.

In the above embodiment, the engine 1 provided with cylinders 5A, 5B, 5C, 5D provided with cylinder liners 4A, 4B, 4C, 4D as separate bodies from the cylinder hole portions 2b, 2c, 2d, 2e of the cylinder block 2. Although applied, it can also be applied to engines with linerless cylinders. When applied to this engine, an opening having the same shape as that of the embodiment is formed in the peripheral wall of the cylinder formed in the cylinder block (for example, the peripheral wall in which the sliding surface of the cylinder is subjected to a predetermined treatment).

In the above embodiment, the shape of the opening 4b of the cylinder liners 4A, 4B, C, 4D is formed so as to follow the shape of the notch 6g of the piston skirt 6b, but the opening is formed in the skirt portion 6f of the piston skirt 6b. As long as it is not opened to the range including 6f, the configuration may not be formed so as to follow the shape of the notch 6g. For example, if it is on the crankshaft 3 side of the piston ring 6e (oil ring), the opening may be widened to the piston ring 6e side of the notch 6g of the piston skirt 6b.

1 Engine 2 Cylinder block 2a Cylinder case 2b, 2c, 2d, 2e Cylinder hole 2g, 2h Continuous passage 3 Crankshaft 4A, 4B, 4C, 4D Cylinder liner 4a Circumferential wall 4b Opening 5A, 5B, 5C, 5D Cylinder 6A , 6B, 6C, 6D Piston 6a Piston body 6b Piston skirt 6c, 6d, 6e Piston ring 6f Skirt part 6g Notch part 7A, 7B, 7C, 7D Connecting rod

Claims (3)

A cylinder block multiple cylinders are provided,
A piston that is reciprocally housed in the cylinder and
The piston ring attached to the piston and
The crankshaft connected to the piston and
Equipped with
The piston has a piston body to which the piston ring is mounted and a piston skirt provided on the crankshaft side of the piston body.
An opening in the peripheral wall of the cylinder is opened on the crankshaft side and on the other cylinder side adjacent to the cylinder from the position of the piston ring when the piston is located at the bottom dead center in the cylinder. The part is formed,
The cylinder block is formed with a communication passage that communicates the opening of one adjacent cylinder among the plurality of cylinders with the opening of another cylinder .
The engine is characterized in that the opening is formed along the shape of a notch between a pair of facing skirts of the piston skirt when the piston is located at bottom dead center in the cylinder. .. A cylinder liner provided in the cylinder block is provided.
The engine according to claim 1, wherein the opening is formed in the cylinder liner. In the communication passage, when the piston in one of the adjacent cylinders of the plurality of cylinders and the other cylinder is moving toward the bottom dead point side, the piston in the other cylinder is moved up. The engine according to claim 1 or 2 , wherein the engine is formed between one cylinder and the other cylinder of a combination that moves to the dead point side.

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