JP6057667B2 - Internal combustion engine cylinder block - Google Patents

Description

  The present invention relates to a cylinder block constituting an internal combustion engine.

  The cylinder block of the internal combustion engine is provided with a water jacket so as to surround the cylinder bore for cooling, and cooling water is allowed to flow through the water jacket. On the other hand, as disclosed in Patent Document 1, it is also widely performed that the cylinder block has a structure in which a steel cylinder liner is cast into a block body made of aluminum.

A cylinder head is overlapped and fixed to the cylinder block so as to block the cylinder bore. Fresh air is supplied to the cylinder bore from an intake port provided in the cylinder head, and combustion gas is discharged to an exhaust port provided in the cylinder head. The In the case of multi-cylinder internal combustion engine, the water jacket so as to surround the row of cylinder bores are formed, although the portion between the water jacket and the cylinder bore is in the inner wall, conventionally, regardless of whether the cylinder liner The thickness of the inner wall on the intake side and the thickness of the inner wall on the exhaust side are equal.

CD-ROM of Japanese Utility Model Publication No. 5-27255

  Now, in a spark ignition type internal combustion engine, the combustion mode in which the flame spreads around the ignition plug at a constant speed is ideal, but when looking at the temperature of the inner peripheral surface of the cylinder bore during engine operation, The exhaust port side is hotter than the intake port side. For this reason, fresh air (air mixture) is heated on the side close to the exhaust port in the cylinder bore during the intake stroke, so that fresh air is easily combusted on the side close to the exhaust port, resulting in early ignition. May cause knocking, and high combustion pressure may not be secured due to uneven combustion speed.

  In addition, fresh air supplied from the intake port generates a swirling flow (tumble flow) that first collides with the exhaust port side of the cylinder bore and then returns to the intake port side during the intake stroke. However, because the cylinder bores a strong and long collision with the hottest part of the cylinder bore, the charging efficiency decreases due to the rise in the temperature of fresh air, or the phenomenon that unburned gas remains on the side of the intake port where the temperature is low, There was also a risk of hindering the improvement of fuel consumption and causing deterioration of the exhaust gas components.

In particular, the cylinder block, the steel cylinder liners in an aluminum block body is a casting Mareta structure, the cooling function is exhibited steel has low thermal conductivity compared to aluminum by the cooling water of the water jacket Therefore, the temperature difference inside the cylinder bore appears remarkably, and the above-mentioned problems are likely to occur.

  Such a problem caused by the temperature difference between the cylinder bores can be solved by making the inner wall thinner and improving the cooling function by cooling water, but there is a limit to making the inner wall thinner in order to ensure strength. In addition, if the inner wall is made thinner, the flow rate of the cooling water must be increased, which causes another problem that the capacity of the water pump and the radiator must be increased.

  The present invention has been made in view of such a current situation, and intends to realize a reduction in the temperature of fresh air, equalization of the temperature of the inner periphery of the cylinder bore, and improvement of the cooling function with a simple structure.

  The above-mentioned problem is mainly caused by a temperature difference in the inner peripheral direction of the cylinder bore, and it can be said that the problem can be solved by reducing the temperature difference. The inventor of the present application has completed the present invention based on such an idea.

That is, in the invention of claim 1, a plurality of cylinder bores are formed side by side in the crank axis direction, and a water jacket surrounding the group of cylinder bores opens toward the cylinder head side.
Between each of the cylinder bores and the water jacket, an intake side inner wall located on one side with the cylinder bore row interposed therebetween and an exhaust side inner wall located on the other side across the cylinder bore row are formed. Configuration,
While the exhaust-side inner wall and the intake-side inner wall are formed so that the exhaust-side inner wall is thinner than the intake-side inner wall at any part in the circumferential direction,
The water jacket is formed so that the intake side and the exhaust side have the same groove width over the entire height at any part in the circumferential direction.

The present invention can be suitably embodied by using a cylinder liner. This is specified in claim 2. That invention of claim 2, in claim 1, wherein the cylinder bore is constituted by a cylinder liner cast into the block body, by shifting the previous SL cylinder liner on the exhaust side, the thickness of the inner wall of the exhaust-side The thickness is made thinner than the thickness of the inner wall on the intake side .

In the present invention, the thickness of the inner wall on the exhaust side of the cylinder block is thin, so even if the amount of cooling water flowing through the water jacket is the same as before, the inner wall on the exhaust port side is effectively cooled and the temperature is higher than before. Can be lowered. Thus, it is possible to prevent the abnormal high temperature portion of the fuel in the combustion chamber, it can be prevented or significantly inhibit knocking due to pre-ignition. In addition, since the flame propagation speed can be made uniform and complete combustion can be promoted, it is possible to contribute to improvement of fuel consumption and prevention of deterioration of exhaust gas components.

  In addition, the temperature of the portion of the cylinder bore where fresh air (mixed air) is most strongly applied can be lowered, so the temperature drop of the whole fresh air can be promoted. This improves the charging efficiency and contributes to fuel efficiency. it can. Similarly, since the temperature rise of the fresh air can be suppressed, the fresh air flows through the cylinder bore during the intake / compression stroke and flows in the cylinder bore. As a result, a phenomenon in which unburned gas partially remains can be prevented, and this can contribute to improvement in fuel consumption and exhaust gas.

  The present invention can also be applied to a cast iron cylinder block not provided with a cylinder liner. However, when the present invention is applied to a cylinder block having a block body made of aluminum or the like and a cylinder liner made of steel or the like by adopting claim 2, casting is performed. At this time, a cylinder block having a different inner wall thickness can be easily manufactured by simply shifting the position of the cylinder liner. Even when a variety of cylinder blocks with different wall thicknesses are available, this can be easily handled.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows 1st Embodiment, (A) is a top view of a cylinder block, (B) is the BB view sectional drawing of (A) in the state which displayed the cylinder head. (A) is a partial top view of 2nd Embodiment, (B) is a partial top view of 3rd Embodiment.

(1). First Embodiment Next, an embodiment of the present invention will be described with reference to the drawings. First, the first embodiment shown in FIG. 1 will be described. The present embodiment is applied to a three-cylinder spark ignition internal combustion engine. The cylinder block 1 has three cylinder bores 3 into which the pistons 2 are slidably fitted, and the cylinder block 3 faces upward. An open water jacket 4 is formed in a closed loop shape.

  The water jacket 4 does not completely surround each cylinder bore 3, and between adjacent cylinder bores 3 is a bore portion 5 in which the cylinder block 1 is inserted. Accordingly, the circumference of the cylinder bore 3 is composed of a pair of inner walls 6 and 7 and the bore portion 5 except for the outer portions of the cylinder bore 3 located at both ends, and the outer side of the water jacket 4 is an outer wall 8. ing.

Most of the cylinder block 1 is composed of an aluminum cast block main body 9, and the cylinder bore 3 is composed of a steel liner 10 cast into the block main body 9. Therefore, the inner walls 6 , 7 and the bore portion 5 have a plurality of structures of the block main body 9 and the cylinder liner 10.

  A cylinder head 12 is overlapped and fixed on the upper surface of the cylinder block 1 via a gasket 11. The cylinder head 12 is formed with a roof-shaped recess 13 that constitutes a combustion chamber so as to face each cylinder bore 3. A spark plug 14 is screwed into the center of the recess 13, and An intake port 15 and an exhaust port 16 opened at the place 13 are provided. The intake port 15 is provided with an intake valve 17, and the exhaust port 16 is provided with an exhaust valve 18.

  The intake port 15 and the exhaust port 16 are arranged symmetrically with a longitudinal center line 19 (a line connecting the centers of the cylinder bores 3) 19 extending in the direction in which the cylinder bores 3 are arranged. Note that two intake ports 15 and two exhaust ports 16 correspond to one cylinder bore 3 and are arranged side by side in the longitudinal direction of the longitudinal center line 19. Accordingly, although the intake and exhaust valves 17 and 18 do not appear accurately on the cut surface taken along the line BB in FIG. 1A, the intake and exhaust valves 17 and 18 are displayed for convenience in FIG. Yes. Needless to say, an intake manifold is connected to each intake port 15 from the outside, and an exhaust manifold is connected to each intake port 16 from the outside.

Since the intake port 15 and exhaust port 16 are disposed on both sides of the center line 19 of the cylinder block 1, the inner wall 6 of the cylinder block 1, the inner wall of the intake side located on the side of the intake port 15 6 And the exhaust-side inner wall 7 located on the exhaust port 16 side . Hereinafter, the inner wall 6 on the intake side is referred to as the intake side inner wall 6, and the inner wall 7 on the exhaust side is referred to as the exhaust side inner wall 7.

  In this embodiment, the cylinder liner 10 is shifted (offset) by a slight dimension E1 toward the exhaust port 16 so that the thickness T1 of the exhaust side inner wall 7 is made thinner than the thickness T2 of the intake side inner wall 6. Yes. Since the cylinder liner 10 has the same thickness over the entire circumference, the difference in thickness T1, T2 between the exhaust side inner wall 7 and the intake side inner wall 6 is realized by the difference in the thickness of the block body 9.

  Further, in the present embodiment, the portion constituting the outer surface of the inner walls 6 and 7 of the water jacket 4 is formed in an arc shape having a center 21 of curvature at a position shifted from the axis 20 of the cylinder liner 10 by E1. For this reason, the thickness of the inner walls 6 and 7 is such that the position of the short center line 22 perpendicular to the longitudinal center line 19 and passing through the center of each cylinder bore 3 is the thinnest, and the distance from the short center line 22 increases. It is thick.

That is, the thicknesses of the inner walls 6 and 7 are not constant in the circumferential direction . Therefore, in this embodiment, the comparison between the thickness of the intake side inner wall 6 and the thickness of the exhaust side inner wall 7 is the longitudinal center line. It must be performed in a symmetrical position with 22 in between. As clearly shown in FIG. 1B, the intake-side inner wall 6 and the exhaust-side inner wall 7 have the same thickness in the height direction. On the other hand, the water jacket 4 has an inner peripheral surface and an outer peripheral surface that are concentric arcs centered on a point 21, and therefore the water jacket 4 has the same groove width over the entire height on the intake side and the exhaust side. It has become.

  As described above, since the thickness T1 of the exhaust side inner wall 7 is thinner than the thickness T2 of the intake side inner wall 6, the heat absorption action of the exhaust side inner wall 7 by the cooling water can be promoted, so that the exhaust side inner wall 7 of the cylinder bore 3 can be promoted. It can suppress that the location of becomes high temperature. As a result, the pre-ignition phenomenon in which fresh air (air-fuel mixture / fuel) is heated at the exhaust-side inner wall 7 and abnormally heated to ignite before ignition by the spark plug 14 can be prevented, and knocking can be prevented.

  Moreover, since the temperature rise of the fresh air can be suppressed as a whole by suppressing the temperature rise of the exhaust side inner wall 7, the charging efficiency can be improved and the resistance to the piston 2 in the compression stroke can be suppressed, thereby contributing to the improvement of fuel consumption. it can.

  The fresh air that has flowed into the cylinder bore 3 from the intake port 15 in the intake stroke strikes the exhaust port 16 and changes its direction further upward by the intake port 15 as indicated by an arrow in FIG. Although the tumble flow 23 is generated, if the temperature of the exhaust-side inner wall 7 is abnormally high, fresh air collides with the exhaust-side inner wall 7 and then rises before colliding with the intake port 15 by receiving heat and expanding. As a result, there is a case where fresh air that has not been tumbled remains on the intake port 15 side and remains without being burned, as indicated by the dot gathering area 24 in (B). For this reason, fuel consumption and exhaust gas components may be deteriorated.

  On the other hand, in this embodiment, since the temperature rise of the exhaust side inner wall 7 can be suppressed, the fresh air hitting the exhaust side inner wall 7 can be transferred to the intake side inner wall 6 so as to lick the top surface of the piston 2. As a result, the entire fresh air can be burned to contribute to improved fuel consumption and exhaust gas.

(2). Other Embodiments / Others Next, a reference example shown in FIG. 2 and other embodiments will be described. In the reference example shown in FIG. 2A, the inner walls 6 and 7 are set to have a uniform thickness in a wide range along the circumferential direction, and the outer portion of the exhaust-side inner wall 7 in the water jacket 4. The groove width of 4 'is made larger than the groove width of the outer portion 4 "of the intake side inner wall 6. That is, in this embodiment, the water jacket 4 is shifted toward the exhaust port 16, and the exhaust port 16 The groove width of the water jacket 4 is changed between this side and the intake side inner wall 6 side.

Na us, the sum of the groove width of the portion of the intake-side inner wall 6 of the water jacket 4 and part of the exhaust-side inner wall 7 is preferably is set to the same as before. Also, the water jacket 4 may be set to equal the dimensions in the outer portion and the outer portion of the exhaust-side inner wall 7 of the intake-side inner wall 6, this case is an embodiment of the present invention.

  In the embodiment shown in FIG. 2B, the difference in thickness T1, T2 between the intake side inner wall 6 and the exhaust side inner wall 7 is realized by changing the thickness t of the cylinder liner 10. That is, the cylinder liner 10 is decentered so that the exhaust side inner wall 7 side is thin by decentering the inner and outer peripheral axes by a small dimension E2. The uneven-thickness cylinder liner 10 can be easily manufactured by using a cast steel product. When the cylinder liner 10 is a cast steel product, adjacent ones can be connected to each other at the bridge portion.

  In the embodiment of (B), the thicknesses T3 and T4 of the block body 9 are set to be equal at the locations of the intake side inner wall 6 and the exhaust side inner wall 7, but a relationship of T3> T4 may be employed. Further, a heat radiating means such as a large number of ribs and grooves may be provided on the outer peripheral surface of the cylinder liner 10.

  The present invention is actually applicable to an internal combustion engine such as a gasoline engine. Therefore, it can be used industrially.

DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Piston 3 Cylinder bore 4 Water jacket 5 Bore part 6 Intake side inner wall ( intake side inner wall)
7 Exhaust side inner wall ( exhaust side inner wall)
9 Block body 10 Cylinder liner 12 Cylinder head 13 Recess 14 Spark plug 15 Intake port 16 Exhaust port 19 Longitudinal center line

Claims (2)

A plurality of cylinder bores are formed side by side in the crank axis direction, and a water jacket surrounding the group of cylinder bores opens toward the cylinder head,
Between each of the cylinder bores and the water jacket, an intake side inner wall located on one side across the cylinder bore row and an exhaust side inner wall located on the other side across the cylinder bore row are formed. Configuration,
While the exhaust-side inner wall and the intake-side inner wall are formed so that the exhaust-side inner wall is thinner than the intake-side inner wall at any part in the circumferential direction,
The water jacket is formed so that the intake side and the exhaust side have the same groove width over the entire height in any part in the circumferential direction.
Cylinder block for internal combustion engines. The cylinder bore is constituted by a cylinder liner cast into the block body, by shifting the previous SL cylinder liner on the exhaust side, the thickness of the inner wall of the exhaust side and thinner than the thickness of the inner wall of the intake-side ing,
The cylinder block of the internal combustion engine according to claim 1.

Images