JP4290076B2 - Water-cooled internal combustion engine - Google Patents

Description

  The present invention relates to a water-cooled internal combustion engine including a cylinder block formed with a water jacket surrounding a cylinder barrel provided with a cylinder bore into which a piston is fitted so as to be reciprocally movable.

As this type of water-cooled internal combustion engine, in the internal combustion engine disclosed in Patent Document 1, a cylinder block includes a cylinder sleeve body in which four cylinder sleeves are integrally connected via a connection wall, and a cylinder sleeve body. A cylinder block body. Each cylinder sleeve forms a cylinder bore into which the piston fits in a reciprocating manner, and a water jacket surrounding four cylinder sleeves arranged in series is formed in the cylinder sleeve body.
Japanese Examined Patent Publication No. 2-48735

  In the cylinder sleeve body of the prior art (corresponding to a cylinder barrel provided with a cylinder bore), in the cylinder sleeves at both ends in the arrangement direction of the four cylinder sleeves, one of the parts facing each other in the arrangement direction is a connecting wall. And the other part is not connected to the connecting wall to form a water jacket, so that the other part is cooled and cooled to a temperature lower than the one part, and between the two end cylinder sleeves. The temperature distribution in the circumferential direction is higher (that is, the uniformity is lower) than the two intermediate cylinder sleeves that are positioned at the opposite sides in the arrangement direction and are connected to the connecting wall. Therefore, the non-uniform temperature distribution in the circumferential direction or arrangement direction of the pistons fitted to the end cylinder sleeves causes the pistons fitted to the intermediate cylinder sleeves. It was higher than that of the ton. Furthermore, the temperature distribution in the circumferential direction in each end cylinder sleeve is different from that in the intermediate cylinder sleeve. Therefore, the temperature distribution in the circumferential direction or arrangement direction of the piston fitted to each end cylinder sleeve is also different from that in the intermediate cylinder. Different from the piston fitted to the sleeve, the non-uniformity of temperature distribution between cylinder sleeves and between pistons was also high.

For this reason, in order to make the gap between the piston and the cylinder sleeve at the time of thermal expansion appropriate, it is close to the top surface of the piston. Considering the nonuniformity of the temperature distribution in the circumferential direction and the nonuniformity of the temperature distribution between the pistons, it took a lot of time to design and manufacture the piston.
Further, in each end cylinder sleeve, a water jacket exists outside the other portion in the radial direction, and accordingly, the cylinder block is enlarged in the arrangement direction.

  Further, the nonuniformity of the temperature distribution in the circumferential direction of one piston is caused by an internal combustion engine, for example, a single cylinder, in which a water jacket is formed that surrounds the entire circumference of a cylinder barrel provided with one cylinder bore into which the piston is fitted. It also occurs in internal combustion engines. Specifically, the exhaust side portion of the piston, which has a large heat load because it is near the exhaust port through which high-temperature combustion gas circulates, is near the intake port through which low-temperature intake air (fresh air) circulates compared to the combustion gas Therefore, the temperature is higher than that of the intake side portion of the piston with a small thermal load. Therefore, as in the case described above, it takes a lot of time to design and manufacture the piston in consideration of the uneven temperature distribution in the circumferential direction of the piston. Moreover, since the water jacket is formed so as to surround the entire circumference of the cylinder barrel, the size of the cylinder block has been increased.

The present invention has been made in view of such circumstances, the invention of claim 1 to 12, wherein, in the water-cooled internal combustion engine, the piston by to achieve uniform temperature distribution in the circumferential direction of the piston The purpose of the present invention is to facilitate the design and manufacture and to reduce the size of the cylinder block on which the driving force transmission member of the valve train is arranged . The invention according to claim 2 aims to achieve the object of the invention according to claim 1 in a water-cooled internal combustion engine comprising an integrated cylinder barrel provided with a plurality of cylinder bores, and the invention according to claim 3 Furthermore, for the purpose of further uniforming the temperature distribution in the circumferential direction of each piston, the invention of claim 6 is claimed in a water-cooled internal combustion engine having a single cylinder barrel provided with one cylinder bore. is intended to achieve the object of the invention of claim 1, wherein,請 Motomeko 11 the described invention, further, to facilitate the adjustment of the degree of cooling suppression in cooling suppression unit, a more uniform temperature distribution The purpose is to plan.

According to a first aspect of the present invention, there is provided a cylinder block having a single cylinder barrel provided with at least one cylinder bore formed by a peripheral wall and a cylinder block outer peripheral portion surrounding the cylinder barrel, and fitted in the cylinder bore so as to be reciprocally movable. And a piston connected to a crankshaft , wherein a water jacket surrounding the cylinder barrel in the circumferential direction is formed in the cylinder block. The cylinder barrel and the cylinder block outer periphery are cooled. The water jacket is connected by a suppressing portion, and the water jacket is divided in the circumferential direction by the cooling suppressing portion for equalizing the temperature distribution in the circumferential direction of the piston , and the cooling suppressing portion includes a cylinder axis of the cylinder bore And intersects with a plane parallel to the rotation center line direction of the crankshaft. A portion of the chamber wall that forms a storage chamber in which a driving force transmission member of a valve train that drives the engine valve of the internal combustion engine is stored at a position adjacent to the cylinder bore in the direction of the rotation center line Is a water-cooled internal combustion engine.

According to this, in a peripheral wall forming a cylinder bore (hereinafter referred to as “specific cylinder bore”) of cylinder bores provided in the cylinder barrel, when there is no cooling suppression portion, a piston (hereinafter referred to as “specific cylinder bore”). The portion where the uniformity of the temperature distribution in the circumferential direction of the “specific piston” is reduced, for example, the portion that is excessively cooled by the water jacket as compared with other portions, By configuring the cooling suppression portion in which the cooling effect is suppressed by dividing the jacket in the circumferential direction, the temperature distribution in the circumferential direction of the specific piston is made uniform, and the uniformity thereof is improved. Thermal expansion is also made uniform, and the uniformity of the amount of thermal expansion in the circumferential direction is improved. In addition, there is no water jacket radially outward of the cooling suppression part, and the cooling suppression part also serves as a part of the outer periphery of the cylinder block. The block can be made smaller.
In addition, since the storage chamber is formed by using the cooling suppression portion, the storage chamber can be formed at a position close to the specific cylinder bore as much as the water jacket does not exist. A driving force transmission member of the system can be arranged.

According to a second aspect of the present invention, in the water-cooled internal combustion engine according to the first aspect, the cylinder barrel is provided with a plurality of predetermined cylinder bores arranged in series and the peripheral wall forms the cylinder bores. An integrated cylinder barrel having a connecting portion interconnected between the cylinder bores adjacent to each other in the arrangement direction of the predetermined number of cylinder bores, and the cooling suppression portion is configured by the predetermined number of cylinder bores And connecting the end bore wall, which is the bore wall forming the end cylinder bore located at both ends in the arrangement direction which is also the rotation center line direction, and the cylinder block outer peripheral portion, in each end bore wall, Ri positions near opposite to the connecting portion in the arrangement direction, one of said end-portion cylinder bores is the Those adjacent to the accommodating chamber in the column direction.

  According to this, in the end bore wall forming the end cylinder bore (corresponding to the specific cylinder bore) at each end in the arrangement direction in the integrated cylinder barrel, the portion facing the connecting portion in the arrangement direction is cooled. When there is no portion, the water jacket is excessively cooled compared to the connecting portion, so that the temperature in the circumferential direction of the end piston (corresponding to a specific piston) fitted to the end bore wall and the end cylinder bore is reduced. This is a part that reduces the uniformity of the distribution. By this part being constituted by the cooling suppression part, the temperature distribution in the circumferential direction of the cooling suppression part is almost the same as the temperature distribution of the connecting part or that Since the temperature distribution can be approximated, the temperature distribution in the circumferential direction of the end piston is made uniform, and furthermore, the pipes fitted to all the cylinder bores of the integrated cylinder barrel are fitted. Temperature distribution in the circumferential direction between tons each other are uniform, are thermal expansion also uniformity of pistons, thereby improving the uniformity of the thermal expansion amount. In addition, the cylinder block can be made smaller in the arrangement direction because there is no water jacket on the outside in the radial direction of the cooling suppression portion in the arrangement direction.

According to a third aspect of the present invention, in the water-cooled type internal combustion engine according to the second aspect, the internal combustion engine includes a cylinder head coupled to the cylinder block, and the water jacket is formed by the cooling suppression unit by the integrated cylinder barrel. The cooling water from the water pump is separated from the intake-side water jacket and the exhaust-side water jacket that are separated from each other, and the head-side water jacket formed on the cylinder head is circulated through the exhaust-side water jacket. Then, the intake-side water jacket is circulated.

According to this, the cylinder barrel having a large heat load and the exhaust side portion of the piston are cooled by the relatively low-temperature cooling water in the water jacket, and the cylinder barrel having a small heat load compared to the cylinder barrel and the exhaust side portion of the piston and Since the piston intake side portion is cooled by the cooling water heated after cooling the cylinder barrel exhaust side portion and cylinder head, the temperature distribution in the circumferential direction at the exhaust side portion and intake side portion of each piston Is made uniform, and the temperature distribution in the circumferential direction of each piston is made more uniform.
According to a fourth aspect of the present invention, in the water-cooled internal combustion engine according to the third aspect, the cooling water is supplied to the exhaust-side water jacket in the cylinder having the end bore wall that forms the one end cylinder bore. It flows in from the intake side water jacket in a cylinder that flows in a direction opposite to the plane and has an intermediate bore wall located between the bore walls at both ends.
According to a fifth aspect of the present invention, in the water-cooled internal combustion engine according to the second aspect, the internal combustion engine includes a cylinder head coupled to the cylinder block, and the water jacket is formed by the cooling suppression unit by the integrated cylinder barrel. The cooling water from the water pump is circulated through the first supply passage and the second supply passage to the exhaust side water jacket. Then, after flowing into the intake-side water jacket in a direction opposite to the plane, they flow into a head-side water jacket formed on the cylinder head .

According to a sixth aspect of the present invention, in the water-cooled internal combustion engine according to the first aspect, the cylinder barrel is a single cylinder barrel provided with one cylinder bore, and the cooling suppression portion is located at an intake side portion of the peripheral wall. To do.

  According to this, in the peripheral wall of the single cylinder barrel provided with a single cylinder bore (which is also a specific cylinder bore) into which the piston is fitted, the intake side portion with a small heat load is water when there is no cooling suppression portion. Since the jacket is excessively cooled compared to the exhaust side portion where the heat load is high, the circumferential wall and the piston (which is also a specific piston) are portions that reduce the uniformity of the temperature distribution in the circumferential direction. Since this part is constituted by the cooling suppression part, the temperature distribution in the circumferential direction can be made substantially the same as or close to the temperature distribution in the exhaust side part, so the temperature distribution in the circumferential direction of the piston Is made uniform, and the uniformity of thermal expansion is improved. In addition, the cylinder block can be made smaller outside in the radial direction at the intake side portion by the amount of the water jacket not present outside in the radial direction at the intake side portion of the peripheral wall by the cooling suppression portion.

A seventh aspect of the present invention is the water-cooled internal combustion engine according to any one of the first to sixth aspects, wherein the cooling suppression portion is recessed toward the cylinder bore in a circumferential direction .
According to an eighth aspect of the present invention, in the water-cooled internal combustion engine according to the seventh aspect, the cooling suppression portion is recessed over the formation range of the cooling suppression portion in a direction orthogonal to the plane.
According to a ninth aspect of the present invention, in the water-cooled internal combustion engine according to the seventh or eighth aspect, the cooling suppression portion is recessed closer to the cylinder bore in the radial direction than the outer peripheral position of the water jacket in the radial direction. It is what is.

A tenth aspect of the present invention is the water-cooled internal combustion engine according to any one of the seventh to ninth aspects, wherein the cooling suppression portion is recessed over a formation range of the water jacket in a cylinder axial direction. It is what.

The invention of claim 11, wherein, in the water-cooled internal combustion engine according to any one of claims 1 to 10, wherein the cooling suppression unit intended to cooling fins for air cooling extending radially outwardly is provided is there.

  According to this, in order to make the temperature distribution in the circumferential direction of the specific piston uniform, when the temperature of the bore wall becomes too high by the cooling suppression unit, the cooling suppression unit can be adjusted by adjusting the heat radiation amount from the cooling fin. The degree of suppression of cooling in can be adjusted so that the temperature of the bore wall is moderate. Moreover, adjustment of the heat radiation amount in the cooling suppression unit can be easily performed by changing the shape and number of cooling fins.

The invention according to claim 12 is the water-cooled internal combustion engine according to any one of claims 1 to 11 , wherein the bore peripheral wall surface of the cylinder bore and the outer peripheral surface of the cylinder block outer peripheral portion in the cooling suppression portion. The thickness in the radial direction between the thickness in the radial direction of the water jacket from the thickness in the radial direction between the bore peripheral wall surface and the outer peripheral surface of the cylinder block outer peripheral portion in the portion where the water jacket is formed. It is smaller than the minimum thickness excluding.

According to this, since the cooling suppression portion is a portion in which the cylinder barrel and the outer peripheral portion of the cylinder block are integrated in the radial direction without the presence of a water jacket outside in the radial direction, Since the rigidity is higher than that of the part where the water jacket is formed, the thickness in the radial direction of the cooling suppression part is the thickness in the radial direction of the cylinder barrel and the cylinder block outer periphery at the part where the water jacket is formed. even smaller than the thickness Mino minimum combined and thickness in the radial direction of the section, it is possible to ensure the required rigidity.

According to invention of Claim 1, the following effect is show | played. In other words, since the uniformity of the thermal expansion amount in the circumferential direction of the specific piston is improved, it becomes easy to design and manufacture the piston so that an appropriate gap is formed between the cylinder barrel and the thermal expansion. , Piston productivity is improved and cost is reduced. In addition, the cylinder block can be downsized radially outward of the cooling suppression portion.
Further, since the driving force transmission member is arranged close to the specific cylinder bore in the rotation center line direction of the crankshaft, it is radially outward of the cooling suppression portion where the driving force transmission member is arranged and in the rotation center line direction. The cylinder block can be reduced in size.

  According to invention of Claim 2, in addition to the effect of the invention of the cited claim, there exists the following effect. That is, since the temperature distribution in the circumferential direction is made uniform among all pistons fitted to the integrated cylinder barrel, an appropriate gap is formed between the piston and the cylinder barrel during thermal expansion. This makes it easy to design and manufacture all pistons that fit into the cylinder barrel, thereby improving productivity and reducing costs. In addition, the cylinder block can be reduced in size in the arrangement direction.

  According to the third aspect of the present invention, the temperature distribution in the circumferential direction of the exhaust side portion and the intake side portion of each piston is made uniform, and the temperature distribution in the circumferential direction of each piston is made more uniform. The effect of the invention of claim 2 is further enhanced.

According to the invention described in claim 6 , in addition to the effect of the invention described in the cited claim, the following effect is exhibited. That is, since the temperature distribution in the circumferential direction of the piston fitted to the single cylinder barrel is made uniform, the piston design and design to ensure that an appropriate gap is formed between the cylinder barrel during thermal expansion. Manufacturing becomes easier, productivity is improved, and costs are reduced. In addition, the cylinder block can be downsized radially outward at the intake side portion.

According to the invention described in claim 11 , in addition to the effect of the invention described in the cited claim, the following effect is produced. That is, since the degree of cooling suppression in the cooling suppression unit can be adjusted by the heat radiation amount of the cooling fin, it is easy to adjust the degree of cooling suppression in the cooling suppression unit, and the temperature distribution of the specific piston can be made more uniform. it can.

According to the invention described in claim 12 , in addition to the effect of the invention described in the cited claim, the following effect is exhibited. That is, the cylinder block can be further reduced in size at the portion where the cooling suppression portion is formed, while ensuring the required rigidity of the cylinder block.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
1-3 is a figure explaining 1st Embodiment of this invention. First, referring to FIGS. 1 and 2, a water-cooled internal combustion engine E to which the present invention is applied is a DOHC type in-line four-cylinder four-stroke internal combustion engine, and a rotation center whose crankshaft 6 is oriented in the vehicle width direction. The motorcycle is mounted in a horizontal arrangement so as to have a line L1.

  The internal combustion engine E includes a cylinder block 1 in which four first to fourth cylinders C1 to C4 are integrally formed, a cylinder head 2 coupled to an upper end portion of the cylinder block 1 via a gasket G, and a cylinder head 2 A head cover 3 coupled to the upper end of the cylinder, an upper crankcase 4a provided integrally with the cylinder block 1 and extending downward and rearward of the cylinder block 1, and a lower crankcase coupled to the lower end of the upper crankcase 4a. The engine main body comprised from 4b and the oil pan 5 couple | bonded with the lower crankcase 4b is provided. Here, the upper crankcase 4 a and the lower crankcase 4 b constitute the crankcase 4. Further, the upper crankcase 4 a may be provided separately from the cylinder block 1 and coupled to the lower end portion of the cylinder block 1.

In the specification, the top, bottom, front, back, left and right coincide with the top, bottom, front, back, left and right of the motorcycle, respectively, and the left and right direction coincides with the vehicle width direction of the motorcycle.
In the specification or claims, the radial direction and the circumferential direction mean directions when the cylinder axis L2 of the cylinder bores B1 to B4 is set as the center. Further, the intake side means the side where the intake port 12a is arranged with respect to the central plane H (see FIG. 2), and the exhaust side means the side where the exhaust port 13a is arranged with respect to the central plane H. Here, the center plane H is a plane including the cylinder axis L2 and parallel to the rotation center line L1, or including the rotation center line L1, or a plane including the cylinder axis L2 and orthogonal to the rotation center line L1.

  The internal combustion engine E constitutes a power unit together with a transmission (not shown) that changes the rotational speed of the crankshaft 6. The crankshaft 6 and the transmission are a crank chamber 7 formed by a crankcase 4 (see FIG. 3). ) And the transmission chamber.

  Cylinder bores B1 to B4 having a cylinder axis L2 are formed in each of the cylinders C1 to C4, and pistons P1 to P4 that are fitted to the cylinder bores B1 to B4 so as to be able to reciprocate are connected to the crankshaft 6 via connecting rods 8. . Each of the cylinders C1 to C4 is located with respect to the crankshaft 6 so that the cylinder axis L2 is inclined obliquely forward and upward from the crankshaft 6 toward the cylinders C1 to C4 in a state where the internal combustion engine E is mounted on the motorcycle. It leans forward.

  The crankshaft 6 has bearing portions of both crankcases 4b (FIG. 3 shows the bearing portion 9 of the upper crankcase 4a so that the rotation center line L1 is on the mating surfaces of the upper and lower crankcases 4a and 4b. Is supported rotatably via the main bearing. Referring also to FIG. 3, the crank chamber 7 is composed of four individual crank chambers 7a that are partitioned by the bearing portion and formed for each of the cylinders C1 to C4, and are adjacent to each other in the rotation center line direction A1. 7a communicates with each other by a vent hole 10 formed across the cylinder block 1 and the upper crankcase 4a, and the pressure fluctuation in the individual crank chamber 7a due to the reciprocating motion of the pistons P1 to P4 is reduced, and the pistons P1 to P4 are relieved. The back pressure acting on is reduced.

  1 and 2, the cylinder head 2 includes, for each of the cylinders C1 to C4, a combustion chamber 11 facing the cylinder bores B1 to B4 in the cylinder axial direction A2 and a pair of intake ports 12a. An engine port that opens and closes the pair of intake ports 12a and the pair of exhaust ports 13a, respectively. A pair of intake valves 14 and a pair of exhaust valves 15 and a spark plug (not shown) facing the combustion chamber 11 are provided.

  The internal combustion engine E is further provided with an intake device, a fuel injection valve 18 as a fuel supply device, an exhaust device, and a valve train. The intake device attached to the side surface where the inlet 12b of the intake port 12 opens in the intake side portion which is also the rear portion of the cylinder head 2 includes a throttle body 17 provided with a throttle valve 16, and is measured by the throttle valve 16. The intake air is guided to each intake port 12. A fuel injection valve 18 that supplies fuel to intake air to form a mixture of intake air and fuel is attached to the throttle body 17 and injects fuel into the intake port 12. The exhaust device attached to the side surface where the outlet 13b of the exhaust port 13 opens in the exhaust side portion which is also the front side portion of the cylinder head 2 is configured to convert the exhaust gas which is the combustion gas flowing out from the combustion chamber 11 through the exhaust port 13 into the internal combustion engine. Lead outside the organization E.

  The valve system for driving the intake valve 14 and the exhaust valve 15 includes a valve operating device V housed in a valve operating chamber formed by the cylinder head 2 and the head cover 3, and the valve operating device V for rotating the crankshaft 6. And a timing transmission mechanism T that transmits power for driving in synchronization. The valve operating device V that opens and closes the intake valve 14 and the exhaust valve 15 is a pair of cams that are rotationally driven at a half rotational speed by the power of the crankshaft 6 that is transmitted via the timing transmission mechanism T. Intake camshaft 21 and exhaust camshaft 22 that are shafts, intake cam 23 and exhaust cam 24 that are provided on each camshaft 21 and 22 and rotate together with camshafts 21 and 22, and intake valve 14 And a valve lifter 25 as a cam follower that can come into contact with the exhaust valve 15 respectively. The intake cam 23 and the exhaust cam 24 synchronize the intake valve 14 and the exhaust valve 15 with the rotation of the crankshaft 6 via the valve lifter 25, respectively. To open and close.

The timing transmission mechanism T includes a driving sprocket 26 that is a driving rotating body provided on the crankshaft 6, a pair of driven sprockets 27 and 28 that are driven rotating bodies provided on both cam shafts 21 and 22, and the sprockets 26 to 26. An endless chain 29, which is an endless transmission band that spans 28, is provided. Therefore, the endless chain 29 is a driving force transmission member for driving the intake valve 14 and the exhaust valve 15 in the valve train. The endless chain 29 of the timing transmission mechanism T is accommodated in the accommodating chamber 30 provided in the cylinder block 1 adjacent to the cylinder bore B4 as one end cylinder bore in the rotation center line direction A1. The storage chamber 30 is formed by a chamber wall 31 formed by a part of a cylinder block outer peripheral portion 42 described later. The chamber wall 31 includes a cylinder axis L2 of the cylinder bore B4 and a plane parallel to the rotation center line direction A1 (hereinafter referred to as a center axis direction). In this embodiment, this crank center plane is a portion near the cylinder bore B4 adjacent to the storage chamber 30 in the rotation center line direction A1 at a position intersecting with the center plane H described later in this embodiment. Is constituted by a cooling suppression portion 47b described later.

  In each of the cylinders C1 to C4, the air sucked through the intake device is sucked into the combustion chamber 11 from the intake port 12 via the intake valve 14 opened in the intake stroke in which the pistons P1 to P4 descend, The pistons P1 to P4 are compressed while being mixed with fuel in the ascending compression stroke. The air-fuel mixture is ignited and burned by the spark plug at the end of the compression stroke, and the pistons P1 to P4 driven by the pressure of the combustion gas in the expansion stroke in which the pistons P1 to P4 descend move the crankshaft 6 through the connecting rod 8. Rotating drive. The combustion gas is discharged as exhaust gas from the combustion chamber 11 to the exhaust port 13 through the exhaust valve 15 opened in the exhaust stroke in which the pistons P1 to P4 rise, and is further discharged to the outside through the exhaust device. .

Hereinafter, the structure of the cylinder block 1 and the cooling system of the internal combustion engine E including the water jacket 43 formed in the cylinder block 1 will be mainly described.
Referring to FIGS. 2 and 3, the cylinder block 1 includes a plurality of predetermined numbers, here, an integrated cylinder barrel 41 in which four cylinder bores B1 to B4 are provided in one cylinder barrel, and a cylinder barrel radially outward. A cylinder block outer peripheral portion 42 that surrounds the entire circumference of the cylinder block 41, and between the cylinder barrel 41 and the cylinder block outer peripheral portion 42 in the radial direction in the cylinder block 1, the block side that surrounds the cylinder barrel 41 in the circumferential direction A water jacket 43 is formed.

  In one cylinder block 1, a single cylinder barrel 41 includes four cylinder bores B1 in which cylindrical bore walls W1 to W4 that respectively form cylinder bores B1 to B4 are arranged in series in the vehicle width direction to form a bore row. ˜B4 (in this embodiment, it coincides with the rotation center line direction A1, hereinafter simply referred to as “arrangement direction”). And the peripheral wall W comprised by the four bore walls W1-W4 is provided in the cylinder sleeve 44 which forms the internal peripheral wall which piston P1-P4 slides in each cylinder bore B1-B4, and the outer peripheral side of the cylinder sleeve 44. And a base portion 45 for holding the cylinder sleeve 44. Each cylinder sleeve 44 is cast and integrated with the base portion 45 when the base portion 45 is integrally formed with the cylinder block outer peripheral portion 42 by casting. In FIG. 2, for convenience of illustration, the pistons P <b> 1 to P <b> 4 are illustrated apart from the cylinder sleeve 44.

  The circumferential wall W is located between adjacent cylinder bores B1, B2; B2, B3; B3, B4 with respect to all the cylinder bores B1 to B4 in the arrangement direction, and adjacent bore walls W1, W2; W2, W3; In connecting portions 46a, 46c, 46b in which W4 are connected to each other, and bore walls W1, W4 as end bore walls forming cylinder bores B1, B4 as end cylinder bores positioned at both ends of the bore row, respectively. Cooling suppression portions 47a and 47b located at positions facing the connecting portions 46a and 46b in the arrangement direction. Therefore, each of the bore walls W1 to W4 has a cylinder sleeve 44, and each of the bore walls W1 and W4 has connection portions 46a and 46b and cooling suppression portions 47a and 47b, respectively. Each of the bore walls W2; W3 as an intermediate bore wall located between W1 and W4 has a pair of connecting portions 46a, 46c; 46c, 46b. Therefore, the cylinder bores B1 and B4 are specific cylinder bores, and the pistons P1 and P4 fitted to the cylinder bores B1 and B4, respectively, are specific pistons. Each of the cylinders C1 to C4 has a bore wall W1 to W4 and a part of a cylinder block outer peripheral portion 42 that forms a water jacket 43 surrounding the bore walls W1 to W4.

Since the cooling suppression portions 47a and 47b, which are part of the peripheral wall W, are part of the bore walls W1 to W4, they are connected to the cylinder block outer peripheral portion 42, and the bore walls W1 and W4 and the cylinder block outer peripheral portion 42 of the cylinder barrel 41 And also serves as a part of the cylinder block outer peripheral portion 42. Further, each of the connecting portions 46a, 46b, 46c and each of the cooling suppressing portions 47a, 47b are arranged in the cylinder axis direction A2 from the mating surface 1a with the cylinder head 2 of the cylinder block 1 to the bottom wall 1b of the water jacket 43 (see FIG. 1). ) And is connected to the bottom wall 1b within the range equal to the stroke of the pistons P1 to P4 from the top openings B1a to B4a of the corresponding cylinder bores B1 to B4 or the mating surface 1a in the cylinder axial direction A2. Then, the water jacket 43 is not formed. As a result, each cooling suppression part 47a, 47b has connected bore wall W1, W4 and the cylinder block outer peripheral part 42 continuously over the whole formation range of the water jacket 43 in cylinder axial direction A2. .
Further, as shown in FIG. 2, the cooling suppression portions 47a and 47b are recessed toward the cylinder bores B1 and B4 in the circumferential direction (or viewed from the cylinder axial direction A2 (see FIG. 3)). The cooling suppression portions 47a and 47b are recessed over the formation ranges S1 and S2 of the cooling suppression portions 47a and 47b in a direction orthogonal to the crank center plane. The cooling suppression portions 47a and 47b are recessed closer to the cylinder bores B1 and B4 in the radial direction than the outer peripheral position of the water jacket 43 in the radial direction. Further, the cooling suppression portions 47a and 47b are recessed over the formation range of the water jacket 43 in the cylinder axial direction A2.

Furthermore, for each connecting portion 46a, 46b, 46c, the circumferential width and radial thickness so that the temperature distribution in the circumferential direction is substantially the same between the connecting portions 46a, 46b, 46c, Furthermore, a structure such as a shape including a length in the cylinder axial direction A2 is set, and the cooling distribution portions 47a and 47b are substantially the same as the temperature distribution in the circumferential direction of the coupling portions 46a and 46b facing each other in the arrangement direction. A structure such as a shape including a width in the circumferential direction and a thickness t1 in the radial direction, and a length in the cylinder axial direction A2 is set so that a temperature distribution that is the same or approaches the temperature distribution is obtained. The Here, the thickness t1 is a thickness in the radial direction between the bore peripheral wall surface Bs that defines the diameter of the cylinder bores B1 and B4 and the outer peripheral surface 42s of the cylinder block outer peripheral portion 42 in each of the cooling suppression portions 47a and 47b. .
In the following description, the temperature distribution means the temperature distribution in the circumferential direction unless otherwise specified.

  And in each cooling suppression part 47a, 47b, it is substantially the same as the temperature distribution in the circumferential direction of the connection parts 46a, 46b as described above, or in the radial direction so as to obtain a temperature distribution approaching that temperature distribution. With the thickness t1 set, as shown in FIG. 2, the thickness t1 of each cooling suppression portion 47a, 47b is the majority of the circumferential width of each cooling suppression portion 47a, 47b. It becomes smaller than the minimum value of the thickness obtained by excluding the thickness t3 in the radial direction of the water jacket 43 from the thickness t2 in the radial direction between the bore peripheral wall surface Bs and the outer peripheral surface 42s at the portion where 43 is formed. In other words, the thickness t1 of each cooling suppression portion 47a, 47b is equal to the thickness t4 of the bore walls W1, W4 of the cylinder barrel 41 and the thickness t5 of the cylinder block outer peripheral portion 42 at the portion where the water jacket 43 is formed. It becomes smaller than the minimum value of the thickness.

  Further, the water jacket 43 includes an exhaust side water jacket 43e serving as a first water jacket and an intake side water serving as a second water jacket with the cylinder barrel 41 sandwiched between the coupling portions 46a, 46b, 46c and the cooling suppression portions 47a, 47b. The jacket 43i is divided in the circumferential direction. Since the water jacket 43 continuously opens at the mating surface 1a except for the connecting portions 46a, 46b, 46c and the cooling suppressing portions 47a, 47b, the cylinder block 1 is an open deck type, and the water jacket 43 is a cylinder barrel. 41 is partially enclosed in the circumferential direction.

  The connecting portions 46a, 46b, 46c and the cooling suppressing portions 47a, 47b are weak cooling portions in which the water jacket 43 does not exist radially outward, and the exhaust side water jacket 43e and the intake side water jacket 43i are independent from each other. It is also a dividing part which divides water jacket 43 so that it may become a water jacket. Therefore, the circulation of the cooling water is not performed between the exhaust side water jacket 43e and the intake side water jacket 43i through the connecting portions 46a, 46b, 46c and the cooling suppression portions 47a, 47b. The cooling water means a cooling liquid that is an arbitrary liquid capable of cooling the internal combustion engine E in addition to a cooling liquid that is a mixture of water and antifreeze liquid. In this embodiment, the center plane H is a plane including the cylinder axis L2 and the rotation center line L1.

  For this reason, in each connection part 46a, 46b, 46c and each cooling suppression part 47a, 47b, the thermal radiation to the cooling water of the water jacket 43 is suppressed. And in the cooling suppression parts 47a and 47b, cooling is suppressed compared with the case where the water jacket 43 exists in the radial direction outward, and the temperature distribution of the cooling suppression parts 47a and 47b is also radially outward. Since the temperature distribution of the connecting portions 46a, 46b where the water jacket 43 does not exist is almost the same as or close to the temperature distribution, the temperature distribution of the bore walls W1, W4 and the pistons P1, fitted to the cylinder bores B1, B4 The temperature distribution of P4 is made uniform, and the temperature distribution of each of the bore walls W1, W4 is substantially the same as or close to the temperature distribution of the bore walls W2, W3. Becomes substantially the same as or close to the temperature distribution of the pistons P2 and P3, and the temperature distribution between the bore walls W1 to W4 and between the pistons P1 to P4 is made uniform. Is done.

  Therefore, in this specification and claims, the uniform temperature distribution in the circumferential direction means that for each one bore wall W1, W4 and each piston P1, P4, the cooling suppression portions 47a, 47b are Compared to the case where no temperature is present, it means that the temperatures are substantially the same in the circumferential direction, or that the temperature range defined by the maximum value and the minimum value of the temperature decreases, and between the bore walls W1 to W4 or between the pistons As for P1 to P4, it means that the temperature distribution becomes substantially the same or approaches the same as compared with the case where there is no cooling suppression part 47a, 47b.

  With reference to FIG. 1, the cooling water supply / discharge system 50 which comprises the said cooling system with the water jacket 43 and the water jacket 48 mentioned later is demonstrated. A supply / discharge system 50 for supplying and discharging cooling water to and from the engine body includes a water pump 51 that pumps cooling water, and heat of the high-temperature cooling water after cooling the cylinder block 1 and the cylinder head 2. A radiator 52 that radiates heat, a thermostat 53 that controls the flow and blocking of the cooling water to the radiator 52 according to the warm-up state of the internal combustion engine E, and a conduit and a pipe that are passage forming members that form a passage for guiding the cooling water A pipe group composed of joints.

  The water pump 51 has a pump housing 51a that houses an impeller that is rotationally driven by the power of the crankshaft 6, and the pump housing 51a is attached to the lower crankcase 4b. The piping group guides cooling water from the water jackets 43 and 48 in the engine body to the thermostat 53, and a conduit 54a and a pipe joint 54b that form a supply passage 54 that guides cooling water from the water pump 51 to the water jacket 43. A conduit 55a and a pipe joint 55b forming the discharge passage 55, and a bypass passage 56 for returning the cooling water from the engine main body to the water pump 51 without circulating the radiator 52 when the internal combustion engine E is cold (that is, when warming up). A conduit 56a that forms a cooling passage from the engine main body after the warm-up is completed, a conduit 57a that forms an outflow passage 57 that guides the cooling water from the engine main body to the radiator 52, and a cooling pump that radiates heat at the radiator 52 and cools down. A conduit 58a forming an inflow passage 58 leading to Here, the pipe joint 54b is connected to a portion of the cylinder block outer peripheral portion 42 forming the cylinder C4, and the pipe joint 55b is connected to a portion of the cylinder block outer peripheral portion 42 forming the cylinder C2. The supply passage 54 communicates with the exhaust side water jacket 43e, and the outflow passage 57 communicates with the intake side water jacket 43i via the thermostat 53 and the discharge passage 55.

In the engine body, the cooling water from the water pump 51 flows through the supply passage 54 and flows into the exhaust side water jacket 43e, and the cooling water after cooling the cylinder barrel 41 (see FIG. 2) is the exhaust side water. Cooling water after flowing into the head side water jacket 48 formed in the cylinder head 2 through the communication path formed in the gasket G from the jacket 43e and cooling the combustion chamber 11 is formed in the gasket G from the water jacket 48. The cylinder barrel 41 is cooled by flowing into the intake-side water jacket 43i through the communication path.
Therefore, as shown in FIGS. 2 and 3, the cooling water flows into the exhaust-side water jacket 43e in the cylinder C4 having the bore wall W4 forming the cylinder bore B4 in a direction opposite to the crank center plane. In the cylinder C2 having the bore wall W2 located between the bore walls W1, W4, the air flows out from the intake side water jacket 43i.

  The cooling water from the intake side water jacket 43i is bypassed through a thermostat 53 in which the main valve (not shown) is closed and the bypass valve 53a is opened in the cold state (the state shown in FIG. 1). 56, and then sucked into the water pump 51. After the warm-up is completed, the main valve is opened, and the bypass valve 53a is passed through the outflow passage 57 through the thermostat 53 and then flows into the radiator 52. Then, the heat is dissipated by the radiator 52 to become a low temperature, and is sucked into the water pump 51 through the inflow passage 58.

  For this reason, after the warm-up is completed, the exhaust side portion 41e (see FIG. 2) of the cylinder barrel 41 having a large heat load passes through the radiator 52 because it is near the exhaust port 13 through which high-temperature combustion gas flows. The low-temperature cooling water is cooled by the exhaust-side water jacket 43e that is directly supplied from the water pump 51, and is near the intake port 12 through which low-temperature intake air (fresh air) circulates compared to the combustion gas. The intake side portion 41i of the cylinder barrel 41 having a small size is cooled by an intake side water jacket 43i to which cooling water is supplied after cooling the exhaust side portion 41e of the cylinder barrel 41 and the cylinder head 2 forming the combustion chamber 11. Therefore, the cooling effect of the intake side portion 41i of the cylinder barrel 41 is suppressed, and the exhaust side portion 41e (We, W1e to W4e) and the intake air in the cylinder barrel 41 (or the peripheral wall W, the bore walls W1 to W4). Portion 41i (Wi, W1i~W4i) uniform temperature distribution between is promoted.

Next, operations and effects of the embodiment configured as described above will be described.
A portion of the bore walls W1, W4 forming the cylinder bores B1, B4 provided in the cylinder barrel 41 of the internal combustion engine E is radially outward and between the cylinder block outer peripheral portion 42 and the top openings B1a, C1 of the cylinder bores B1, B4, The cooling suppression portions 47a and 47b that also serve as part of the cylinder block outer peripheral portion 42 without forming the water jacket 43 within the range of the distance equal to the stroke of the pistons P1 and P4 from B4a, The temperature distribution of the pistons P1 and P4 is made uniform by 47b as compared with the case where the cooling suppression portions 47a and 47b are not provided, so that the cooling suppression portions 47a and 47a are formed in the bore walls W1 and W4 forming the cylinder bores B1 and B4. The portion where the uniformity of the temperature distribution of the pistons P1 and P4 is lowered when there is no 47b, that is, the portion facing the connecting portions 46a and 46b in the arrangement direction is Cooling suppression part that is excessively cooled by the water jacket 43 compared to other parts, and the cooling effect is suppressed by dividing the water jacket 43 in the circumferential direction so that this part does not form the water jacket 43 By being composed of 47a and 47b, the temperature distribution in the pistons P1 and P4 is made uniform and the uniformity is improved. As a result, the thermal expansion of the pistons P1 and P4 is also made uniform, and the amount of thermal expansion is reduced. Since the uniformity in the direction is improved, an appropriate gap is formed between the cylinder barrel 41 during thermal expansion, including the design and manufacture of the top land that has the largest thermal expansion because it is close to the top surface of the piston. Design and manufacture of the pistons P1 and P4 for making it easier are facilitated, the productivity of the pistons P1 and P4 is improved, and the cost is reduced.

  The cylinder barrel 41 is provided with four cylinder bores B1 to B4 arranged in series, and the peripheral wall W is an integrated cylinder barrel 41 having connecting portions 46a, 46b, 46c. The cooling suppression portions 47a, 47b The bore walls W1 and W4 that form the end cylinder bores B1 and B4 located at both ends in the arrangement direction of the row are positioned so as to face the coupling portions 46a and 46b in the arrangement direction, so that the cooling suppression portions 47a and 47b Since the temperature distribution can be substantially the same as or close to the temperature distribution of the connecting portions 46a and 46b, the temperature distribution of the pistons P1 and P4 can be made uniform, and all of the integrated cylinder barrel 41 can be made uniform. The temperature distribution is made uniform between the pistons P1 to P4 fitted to the cylinder bores B1 to B4, and the thermal expansion of the pistons P1 to P4 is also made uniform. Since the uniformity is improved, it is easy to design and manufacture all pistons P1 to P4 fitted to the cylinder barrel 41 so that an appropriate gap is formed between the cylinder barrel 41 during thermal expansion. As a result, productivity is improved and costs are reduced.

  In the arrangement direction, the water jacket 43 does not exist radially outward of the cooling suppression portions 47a, 47b, and the cooling suppression portions 47a, 47b also serve as a part of the cylinder block outer peripheral portion 42. Since the cylinder block 1 can be reduced in the arrangement direction, the cylinder block 1 can be reduced in size in the arrangement direction, and the vehicle width of the motorcycle can be reduced in the portion where the cylinder block 1 is arranged. .

Further, the thickness t1 in the radial direction of each cooling suppression portion 47a, 47b is the majority of the width in the circumferential direction of each cooling suppression portion 47a, 47b, and the bore circumferential wall surface Bs at the site where the water jacket 43 is formed. The cooling suppression portions 47a and 47b are disposed on the outside in the radial direction by being smaller than the minimum thickness excluding the radial thickness t3 of the water jacket 43 from the radial thickness t2 between the outer circumferential surface 42s and the outer peripheral surface 42s. A portion in which the water jacket 43 is formed in the cylinder block 1 because the bore walls W1 and W4 and the cylinder block outer peripheral portion 42 are integrated in the radial direction without the water jacket 43 existing on the side. Therefore, the thickness t1 of each of the cooling suppression portions 47a and 47b is set to the thickness t4 of the cylinder barrel 41 and the thickness t5 of the cylinder block outer peripheral portion 42 at the portion where the water jacket 43 is formed. Combined thickness Even if it is smaller than the minimum value, the required rigidity can be ensured. As a result, after the required rigidity of the cylinder block 1 is ensured, the cylinder block 1 can be further miniaturized at the portions where the cooling suppression portions 47a and 47b are formed.

  Further, connecting portions 46a, 46c, 46b are provided between the cylinder bores B1, B2; B2, B3; B3, B4 adjacent to each other in the arrangement direction in the cylinder barrel 41, and the bore walls W1, W4 are connected in the arrangement direction. By providing cooling suppression portions 47a and 47b at portions facing the portions 46a and 46b, there is no connection portion between any adjacent cylinder bores, and the cylinder block 1 is compared to a cylinder block in which a water jacket is provided. Is reduced in size in the arrangement direction.

  The water jacket 43 is divided into an intake-side water jacket 43i and an exhaust-side water jacket 43e that are independent from each other with the integrated cylinder barrel 41 sandwiched by the cooling suppression portions 47a and 47b, and the cooling water flowing through the water jacket 43 is exhausted. After the side water jacket 43e is circulated, the intake side water jacket 43i is circulated through the water jacket 48 formed in the cylinder head 2, so that the cylinder barrel 41 having a large heat load and the exhaust side portions of the pistons P1 and P4 are The cylinder jacket 41 and the pistons P1 to P1 are cooled by a relatively low temperature cooling water in the water jacket 43 and have a smaller thermal load than the cylinder barrel 41 and the exhaust side portions 41e and P1e to P4e (see FIG. 2) of the pistons P1 to P4. The intake side portion 41i, P1i to P4i (see FIG. 2) of P4 cools the exhaust side portion 41e of the cylinder barrel 41 and the cylinder head 2. Then, the temperature distribution is made uniform between the exhaust side portions P1e to P4e and the intake side portions P1i to P4i of the pistons P1 to P4. Since the temperature distribution of P4 is made more uniform, the design and manufacture of the pistons P1 to P4 becomes easier, the productivity is improved, and the cost is reduced.

The cooling suppression unit 47b includes an endless chain 29 of a timing transmission mechanism T that transmits the power of the crankshaft 6 to the camshafts 21 and 22 in the valve train that drives the intake valve 14 and the exhaust valve 15 of the internal combustion engine E. By forming the storage chamber 30 to be stored, the storage chamber 30 is formed using the cooling suppression portion 47b, and therefore the position close to the cylinder bore B4 in the rotation center line direction A1 because the water jacket 43 does not exist. And the endless chain 29 can be disposed close to the cylinder bore B4, so that the cooling center 47b in which the endless chain 29 is disposed is radially outward and the center of rotation. The cylinder block 1 can be reduced in size in the line direction A1 .

  Next, a second embodiment of the present invention will be described. The second embodiment is mainly different from the first embodiment in the cooling water supply / discharge system, and the other is basically the same in configuration. Therefore, the description of the same part is omitted or simplified, and different points will be mainly described. In addition, about the member same as the member of 1st Embodiment, or the corresponding member, the same code | symbol was used as needed.

  Referring to FIG. 4 and part of the reference numerals of FIG. 2 as necessary, in the internal combustion engine E in which the heat load is substantially the same in the exhaust side portion 41e of the cylinder barrel 41 and the intake side portion 41i of the cylinder barrel 41, The cooling water supply / discharge system 60 is formed by a first supply passage 61 and a conduit 62a that lead the cooling water pumped from the water pump 51 to the exhaust-side water jacket 43e by the conduit 61a, and the intake-side water jacket 43i. A thermostat 53 connected to the cylinder head 2 to guide the cooling water from the water jacket 48, a conduit 56 a forming a bypass path 56, and the thermostat 53. And a conduit 57a that forms an outflow passage 57 that guides cooling water from the engine body to the radiator 52, and a conduit 58a that forms an inflow passage 58.

Then, in the engine body, the cooling water from the water pump 51, the exhaust side water jacket 43e and flows through the first supply passage 61, each of the crank in the distribution to the intake side water jacket 43i a second supply passage 62 Cooling water after flowing in the direction opposite to the center plane and cooling the cylinder barrel 41 flows into the water jacket 48 from the exhaust side and intake side water jackets 43e and 43i through the communication passage formed in the gasket G. Then, the combustion chamber 11 is cooled. The cooling water from the water jacket 48 enters the bypass passage 56 through a thermostat 53 in which the main valve (not shown) is closed and the bypass valve 53a is opened when the air is cold (the state shown in FIG. 4). After that, after the warm-up is completed, the main valve opens, the bypass valve 53a passes through the thermostat 53, and then flows through the outflow passage 57 and then flows into the radiator 52. The heat is dissipated at 52 and becomes a low temperature, and is sucked into the water pump 51 through the inflow passage 58.

According to the second embodiment, the same operations and effects as the first embodiment are exhibited except for the effects based on the cooling system of the cooling water, and the following operations and effects are exhibited.
That is, the exhaust side water jacket 43e and the intake side water are applied to the cylinder barrel 41 (the same applies to the peripheral wall W or the bore walls W1 to W4) in which the heat load is substantially the same in the exhaust side portion 41e and the intake side portion 41i. Since the cooling water having substantially the same temperature from the water pump 51 is directly supplied to the jacket 43i, the uniformity of the temperature distribution between the exhaust side portion and the intake side portion of the cylinder barrel 41 and each of the pistons P1 to P4, and consequently The uniformity of the temperature distribution in each piston P1 to P4 and the uniformity of the temperature distribution among the pistons P1 to P4 are maintained.

  Next, a third embodiment of the present invention will be described. The third embodiment is different from the first embodiment in that the internal combustion engine is a single cylinder. In addition, description about the same part as 1st Embodiment is abbreviate | omitted or simplified, and it demonstrates focusing on a different point. In addition, about the member same as the member of 1st Embodiment, or the corresponding member, the same code | symbol was used as needed.

  Referring to FIG. 5, a cylinder head (not shown) is formed with an intake port that opens to the combustion chamber at one intake port 12a and an exhaust port that opens to the combustion chamber at one exhaust port 13a. An intake valve and an exhaust valve that open and close the intake port 12a and the exhaust port 13a, respectively, are provided.

  The cylinder block 1 has a single cylinder barrel 71 in which one cylinder bore B is provided in one cylinder barrel, and a cylinder block outer peripheral portion 72 surrounding the cylinder barrel 71. A block-side water jacket 73 that surrounds the cylinder barrel 71 in the circumferential direction is formed therebetween. The peripheral wall W of the cylinder barrel 71 is composed of one cylindrical bore wall that forms the cylinder bore B, and includes a cylinder sleeve 74 and a base portion 75.

  A part of the peripheral wall W is constituted by a cooling suppression portion 77 provided between the cylinder bore B and the storage chamber 30 for storing the endless chain 29 in the rotation center line direction A1. Therefore, the cylinder bore B is a specific cylinder bore, and the piston P fitted to the cylinder bore B is a specific piston. In this embodiment, the center plane H is a plane that includes the cylinder axis L2 and is orthogonal to the rotation center line of the crankshaft.

  The cooling suppression unit 77 is located in the intake side portion Wi of the peripheral wall W, constitutes a part of the intake side portion Wi, and also serves as a part of the cylinder block outer peripheral portion 72. The water jacket 73 is divided in the circumferential direction by a portion located in the intake side portion Wi of the cylinder block 1 by the cooling suppression portion 77, and partially surrounds the cylinder barrel 71 in the circumferential direction at the peripheral wall W other than the cooling suppression portion 77. It will be. With respect to the cooling suppression unit 77, in the intake side portion Wi, the width in the circumferential direction and the temperature distribution so that a temperature distribution that is substantially the same as or close to the temperature distribution of the exhaust side portion We of the peripheral wall W is obtained. A structure such as a shape including a thickness in the radial direction and a length in the cylinder axial direction is set.

For this reason, in the cooling suppression unit 77, similarly to the cooling suppression units 47a and 47b, the heat radiation of the water jacket 73 to the cooling water is suppressed, and as a result, compared to the case where the water jacket 73 exists radially outward. In the peripheral wall W and the piston P, whether the temperature distribution in the intake side portions Wi and Pi with a small heat load is substantially the same as the temperature distribution in the exhaust side portions We and Pe with a large heat load, with cooling suppressed. Alternatively, since the temperature distribution approaches the temperature distribution, the temperature distribution of the peripheral wall W and the temperature distribution of the piston P are made uniform.
And as FIG. 5 shows, the cooling suppression part 77 is dented toward the cylinder bore B in the circumferential direction (or seeing from a cylinder axial direction). Further, the cooling suppression portion 77 is recessed over the formation range S3 of the cooling suppression portion 77 in a direction orthogonal to the crank center plane. Further, the cooling suppression portion 77 is recessed closer to the cylinder bore B in the radial direction than the outer peripheral position of the water jacket 73 in the radial direction. Furthermore, the cooling suppression part 77 is recessed over the formation range of the water jacket 73 in the cylinder axial direction.

According to the third embodiment, the same operations and effects as the operations and effects related to the bore wall W4 and the piston P4 in the first embodiment are exhibited.
In other words, the cylinder barrel 71 is a single cylinder barrel 71 provided with one cylinder bore B, and the cooling suppression portion 77 is located on the intake side portion Wi of the peripheral wall W, so that the heat load on the peripheral wall W of the cylinder barrel 71 is reduced. Since the small intake side portion Wi is excessively cooled by the water jacket 73 when compared with the exhaust side portion We having a high thermal load when the cooling suppression portion 77 is not provided, the temperature distribution in the peripheral wall W and the piston P is uniform. However, when a part of this part is configured by the cooling suppression unit 77, the temperature distribution can be made substantially the same as or close to the temperature distribution of the exhaust side portion We. Since the temperature distribution in the piston P is made uniform and the uniformity of the thermal expansion amount is improved, an appropriate gap is formed between the cylinder barrel 71 and the thermal expansion. Design and manufacture of the piston P to be formed is facilitated, productivity is improved, and cost is reduced.

In addition, the cylinder block 1 can be reduced radially outward at the intake side portion by the amount of the water jacket 73 not present radially outward at the intake side portion Wi of the peripheral wall W by the cooling suppression portion 77. The cylinder block 1 can be reduced in size radially outward at the intake side portion. Further, in the chamber wall 34 , at the position intersecting with the crank center plane , the cooling suppressing portion 77 that is a part near the cylinder bore B adjacent to the storage chamber 30 in the rotation center line direction A1 is the same as in the first embodiment. In the valve train, by forming the accommodation chamber 30 in which the endless chain 29 of the timing transmission mechanism T is accommodated, the endless chain 29 can be arranged close to the cylinder bore B as in the first embodiment. Therefore, it is possible to reduce the size of the cylinder block 1 outside in the radial direction of the cooling suppressing portion 77 where the endless chain 29 is disposed and in the rotation center line direction A1 .

Hereinafter, an embodiment in which a part of the configuration of the above-described embodiment is changed will be described with respect to the changed configuration.
In each of the embodiments described above, the absence of the water jackets 43, 73 reduces the amount of heat dissipated in the cooling suppression portions 47a, 47b, 77, and makes the temperature distribution in the pistons P1, P4, P uniform. When the temperatures of the bore walls W1 to W4 become too high due to the portions 47a, 47b, 77, the cooling suppression portions 47a, 47b, 77 are connected to the cooling suppression portions as shown by two-dot chain lines in FIGS. One or more cooling fins 80 for air cooling extending radially outward from 47a, 47b, 77 may be provided. The cooling fins 80 have a shape capable of maintaining downsizing in the arrangement direction or the radial direction, and the shape and the number of the cooling fins 80 are for adjusting the degree of cooling suppression of the cooling suppression units 47a, 47b, 77. Therefore, in order to adjust the heat radiation amount from the cooling fin 80, it is set appropriately.

  And by providing the cooling fins 80 for air cooling that extend radially outward in the cooling suppression portions 47a, 47b, 77, by adjusting the amount of heat radiation from the cooling fins 80, the cooling suppression portions 47a, 47b, 77 The degree of cooling suppression can be adjusted so that the temperature of the bore walls W1 and W4 or the peripheral wall W (see FIG. 5) becomes appropriate. Further, the adjustment of the amount of heat radiation in the cooling suppression portions 47a, 47b, 77 can be easily performed by changing the shape and the number of the cooling fins 80. As a result, since the degree of cooling suppression in the cooling suppression units 47a, 47b, 77 can be adjusted by the heat radiation amount of the cooling fin 80, the adjustment of the degree of cooling suppression in the cooling suppression units 47a, 47b, 77 is facilitated, The temperature distribution of the pistons P1, P4, and P can be made more uniform.

  As a cause of increasing the non-uniformity of the temperature distribution in the piston, since there is a side pressure of the piston in the expansion stroke, the non-uniformity of the temperature distribution is increased due to the side pressure of the piston. It may be applied to the peripheral wall of the cylinder barrel. Specifically, the bore wall or the thrust side portion of the peripheral wall on which the side pressure of the piston acts is caused by frictional heat generated by friction with the thrust side portion that exerts the side pressure on the bore wall or the peripheral wall in the piston. Compared with the anti-thrust side portion of the peripheral wall and the anti-thrust side portion of the piston, the heat load is high. Therefore, the thermal load of the bore wall or the peripheral wall and each thrust side portion of the piston is larger than the thermal load of the bore wall or the peripheral wall and each anti-thrust side portion of the piston. In an internal combustion engine in which a water jacket is formed radially outward of the side portion, the bore wall or the peripheral wall and each anti-thrust side portion of the piston are cooled excessively by the water jacket to a low temperature, and the bore wall or the peripheral wall or In the case where the circumferential wall and the piston become a portion that increases the non-uniformity of the temperature distribution in the circumferential direction, the bore wall or the anti-thrust side portion of the circumferential wall is configured with the same cooling suppression unit as in the above embodiment, The temperature distribution can be made uniform in the peripheral wall and the piston.

  The valve operating device V of the internal combustion engine may be of the OHC type including the SOHC type in addition to the DOHC type, and further includes a drive rod such as a push rod provided between the intake cam and the exhaust cam and the cam follower. An OHV type may be used. In the case of the OHV type valve gear V, the drive rod that is a component of the valve gear V corresponds to a driving force transmission member of the valve gear system. Further, the timing transmission mechanism T may be a mechanism using an endless belt as a gear train or an endless transmission band. In this case, the driving force transmission member is a gear train of the timing transmission mechanism T or It becomes an endless belt. Further, the cylinder bores B1 to B4 arranged in series are separated in the arrangement direction by two integrated cylinder barrels or two single cylinder barrels, and the timing transmission mechanism T and the accommodation chamber 30 are arranged between both cylinder barrels. It may be a type of internal combustion engine.

  In the first embodiment, the coupling portions 46a, 46b, 46c and the cooling suppression portions 47a, 47b do not allow substantial cooling water to flow between the intake side water jacket 43i and the exhaust side water jacket 43e. The two water jackets 43i and 43e may be divided. Here, “substantially” means that the cooling water does not circulate at all in the connecting portions 46a, 46b, 46c or the cooling suppression portions 47a, 47b, and the temperature distribution is made uniform compared to the case where no cooling water circulates. This means that a slight amount of cooling water that does not cause a significant difference in terms of the effect may be circulated. Similarly, in the third embodiment, the cooling suppression unit 77 may be configured to divide the water jacket 73 so that substantial cooling water does not flow through the cooling suppression unit 77. In the first embodiment, the center plane H may be a plane including the cylinder axis L2 and parallel to the rotation center line L1. The thermostat 53 may open and close the inflow passage 58.

  The internal combustion engine may be an in-line multi-cylinder internal combustion engine other than four cylinders, and may be a multi-cylinder internal combustion engine having a pair of banks such as a V type. When the internal combustion engine is provided with a pair of banks, the cylinder block of each bank is provided with an integrated cylinder barrel or a single cylinder barrel. The cylinder block may be a closed deck type. The internal combustion engine may be used for a vehicle other than a motorcycle or a machine other than a vehicle.

1 shows a first embodiment of the present invention, and is a side view of an essential part of an internal combustion engine. FIG. 2 is a partial cross-sectional view taken along a line II of FIG. FIG. 2 is an II arrow view of FIG. 1 showing a main part of a cylinder block. It is the III-III sectional view taken on the line of FIG. It is a figure which shows 2nd Embodiment of this invention and corresponds to FIG. FIG. 3 shows a third embodiment of the present invention and corresponds to FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cylinder block, 2 ... Cylinder head, 3 ... Head cover, 4 ... Crankcase, 12 ... Intake port, 13 ... Exhaust port, 30 ... Storage chamber, 41, 71 ... Cylinder barrel, 42, 72 ... Cylinder block outer peripheral part, 43, 48, 73 ... water jacket, 46a, 46b, 46c ... connection part, 47a, 47b, 77 ... cooling suppression part, 50, 60 ... supply / discharge system, 51 ... water pump, 52 ... radiator, 53 ... thermostat, 80 ... cooling fins,
E ... Internal combustion engine, B, B1-B4 ... Cylinder bore, P, P1-P4 ... Piston, T ... Timing transmission mechanism, W ... Circumferential wall, W1-W4 ... Bore wall.

Claims (12)

A cylinder block having a single cylinder barrel provided with at least one cylinder bore formed by a peripheral wall and a cylinder block outer peripheral portion surrounding the cylinder barrel; and a reciprocating fit with the cylinder bore and coupled to a crankshaft that piston and comprises, in water-cooled internal combustion engine in which a water jacket is formed in the cylinder block surrounding the cylinder barrel in the circumferential direction,
The cylinder barrel and the cylinder block outer peripheral part are connected by a cooling suppression part,
The water jacket is divided in the circumferential direction by the cooling suppression portion for equalizing the temperature distribution in the circumferential direction of the piston ,
The cooling suppressing unit includes a driving force transmission member of a valve train system that drives an engine valve of the internal combustion engine at a position that includes a cylinder axis of the cylinder bore and intersects a plane parallel to the rotation center line direction of the crankshaft. A water-cooled internal combustion engine comprising a portion of the chamber wall forming the storage chamber that is close to the cylinder bore adjacent to the storage chamber in the direction of the rotation center line . The cylinder barrel is provided with a plurality of predetermined numbers of cylinder bores arranged in series, and the peripheral wall is formed between the cylinder bores adjacent to each other in the arrangement direction of the predetermined number of cylinder bores. Is an integrated cylinder barrel having connecting parts connected to each other,
The cooling suppression portion is an end portion that is the bore wall that forms end cylinder bores that are located at both ends in the arrangement direction, which is also the direction of the rotation center line, of a bore row constituted by the predetermined number of cylinder bores. with connecting the bore wall of the cylinder block outer periphery, at the each end bore wall, Ri positions near opposite to the connecting portion in the array direction,
The water-cooled internal combustion engine according to claim 1 , wherein the one end cylinder bore is adjacent to the storage chamber in the arrangement direction . The internal combustion engine includes a cylinder head coupled to the cylinder block;
The water jacket is divided into an intake-side water jacket and an exhaust-side water jacket that are independent from each other across the integrated cylinder barrel by the cooling suppression unit,
3. The water cooling according to claim 2, wherein the cooling water from the water pump flows through the exhaust-side water jacket and then flows through the intake-side water jacket through a head-side water jacket formed in the cylinder head. Internal combustion engine. The cooling water flows into the exhaust-side water jacket in a direction opposite to the plane in the cylinder having the end bore wall forming the one end cylinder bore, and is positioned between the both end bore walls. 4. The water-cooled internal combustion engine according to claim 3, wherein the water-cooled internal combustion engine flows out of the intake side water jacket in a cylinder having an intermediate bore wall. The internal combustion engine includes a cylinder head coupled to the cylinder block;
The water jacket is divided into an intake-side water jacket and an exhaust-side water jacket that are independent from each other across the integrated cylinder barrel by the cooling suppression unit,
Cooling water from the water pump flows through the first supply passage to the exhaust-side water jacket, flows through the second supply passage to the intake-side water jacket, and flows into the plane facing the plane, respectively. The water-cooled internal combustion engine according to claim 2, wherein the water-cooled internal combustion engine flows into a head-side water jacket formed in the cylinder head . The cylinder barrel is a single cylinder barrel provided with one cylinder bore,
The water-cooled internal combustion engine according to claim 1, wherein the cooling suppression unit is located at an intake side portion of the peripheral wall. The water-cooled internal combustion engine according to any one of claims 1 to 6, wherein the cooling suppressing portion is recessed toward the cylinder bore in a circumferential direction. The water-cooled internal combustion engine according to claim 7, wherein the cooling suppression unit is recessed over a range in which the cooling suppression unit is formed in a direction orthogonal to the plane. 9. The water-cooled internal combustion engine according to claim 7, wherein the cooling suppression portion is recessed closer to the cylinder bore in the radial direction than an outer peripheral position of the water jacket in the radial direction. 10. The water-cooled internal combustion engine according to claim 7, wherein the cooling suppression portion is recessed over a formation range of the water jacket in a cylinder axial direction. The water-cooled internal combustion engine according to any one of claims 1 to 10, wherein the cooling suppression portion is provided with cooling fins for air cooling extending outward in the radial direction. The thickness in the radial direction between the bore peripheral wall surface of the cylinder bore and the outer peripheral surface of the cylinder block outer peripheral portion in the cooling suppression portion is equal to the bore peripheral wall surface and the cylinder block outer peripheral portion in the portion where the water jacket is formed. any one of claims from the thickness in the radial direction of the claims 1 to 11, characterized in that less than the minimum value of the thickness excluding the thickness in the radial direction of the water jacket between the outer peripheral surface of the Water-cooled internal combustion engine.

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