JP2005320944A - Cooling structure of open deck type cylinder block - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniformly cool a cylinder block near a deck face while minimizing the lowering of the rigidity of the cylinder block. <P>SOLUTION: This open deck type cylinder block is so formed that a water jacket 33 formed to surround the periphery of a cylinder bore 16a is opened to the deck face 11a. The wall thickness of the cylinder block near the deck face 11a between the cylinder bore 16 and the water jacket 33 is set so that a wall thickness Te on the exhaust side is smaller than a wall thickness Ti on the intake side. Accordingly, cooling is promoted by increasing heat conductivity between the cylinder bore 16a on the exhaust side which is liable to be specially heated by the exhaust gas near the deck face 11a which is liable to be heated by combustion, and the water jacket 33 to increase knocking resistance, to increase a compression ratio, to save on fuel consumption, and to increase output. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cooling structure for an open deck type cylinder block in which a water jacket formed on a cylinder block so as to surround a cylinder bore is opened on a deck surface of the cylinder block.

  The wall thickness between the cylinder bore of the cylinder block and the water jacket is increased at the portions corresponding to both ends of the crankshaft in the axial direction, so that the cylinder bore is secured when the cylinder head is fastened to the cylinder block or when the engine is operated. A device for preventing thermal deformation is known from Patent Document 1 below.

  In addition, by increasing the wall thickness between the cylinder bore of the cylinder block and the water jacket at the portions corresponding to the intake side and the exhaust side of the cylinder block, the rigidity of the cylinder block is increased to prevent thermal deformation. It is known from Patent Document 2 below.

Also, by increasing the wall thickness between the cylinder bore of the cylinder block and the water jacket on the side where the side thrust from the piston acts strongly, and reducing the thickness on the side where the side thrust from the piston acts weakly, the cylinder block Patent Document 3 listed below is known to increase the rigidity against side thrust while minimizing the increase in weight of the above.
JP 10-47153 A JP-A-9-79085 JP-A-8-28341

  By the way, the vicinity of the deck surface of the cylinder block to which the cylinder head in which the combustion chamber is formed is coupled is particularly a portion where the temperature is likely to rise, but the intake side near the intake port is relatively low in temperature, The exhaust side near the exhaust port is relatively hot. Therefore, if the exhaust side in the vicinity of the deck surface cannot be sufficiently cooled, the knocking resistance is lowered, which causes a problem that causes a reduction in engine output. In order to increase the cooling performance near the deck surface, the wall between the cylinder bore and the water jacket can be thinned to increase heat transfer, and the water jacket can be widened to increase the flow rate of cooling water. In this case, there is a problem that the rigidity of the cylinder block is lowered.

  The present invention has been made in view of the above circumstances, and an object thereof is to uniformly cool the vicinity of a deck surface of a cylinder block while minimizing a decrease in rigidity of the cylinder block.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided an open deck type cylinder block in which a water jacket formed on the cylinder block so as to surround the cylinder bore opens on the deck surface of the cylinder block. In the cooling structure, the thickness between the cylinder bore and the water jacket in the vicinity of the deck surface of the cylinder block is set so that the thickness on the exhaust side is smaller than the thickness on the intake side. A cooling structure for the block is proposed.

  According to the invention described in claim 2, in addition to the structure of claim 1, the width of the water jacket in the vicinity of the deck surface of the cylinder block is set so that the width on the exhaust side is larger than the width on the intake side. A cooling structure of an open deck type cylinder block is proposed.

  According to the invention described in claim 3, in addition to the structure of claim 1, the thickness of the exhaust side between the cylinder bore and the water jacket in the vicinity of the deck surface of the cylinder block is gradually increased as the distance from the deck surface increases. A cooling structure for an open deck type cylinder block is proposed.

  The cylinder block side water jacket 33 of the embodiment corresponds to the water jacket of the present invention.

  According to the first aspect of the present invention, since the wall thickness between the cylinder bore and the water jacket in the vicinity of the deck surface of the cylinder block is made smaller on the exhaust side than on the intake side, Increases heat transfer between the cylinder bore on the exhaust side, which tends to be particularly hot with exhaust gas, and the water jacket to promote cooling, thereby improving knocking resistance, increasing the compression ratio, reducing fuel consumption, and improving output Can be achieved. Moreover, since the thickness between the cylinder bore and the water jacket is reduced only on the exhaust side near the deck surface of the cylinder block, the reduction in the rigidity of the cylinder block due to the reduction in the thickness can be minimized. it can.

  According to the configuration of the second aspect, since the width of the water jacket in the vicinity of the deck surface of the cylinder block is made larger on the exhaust side than on the intake side, the flow rate of the cooling water that flows through the water jacket on the exhaust side that tends to become high temperature due to the exhaust gas. This can increase the cooling effect. In addition, since the wall thickness between the cylinder bore and the water jacket is small on the exhaust side where the width of the water jacket is large, it is possible to prevent the side wall on the exhaust side of the cylinder block from becoming thicker than the side wall on the intake side.

  According to the configuration of the third aspect, the thickness of the exhaust side between the cylinder bore and the water jacket in the vicinity of the deck surface of the cylinder block gradually increases as the distance from the deck surface increases. Rigidity can be ensured.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.

  1 to 4 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of an engine (a sectional view taken along line 1-1 in FIG. 2, FIG. 2 is a sectional view taken along line 2-2 in FIG. FIG. 3 is an enlarged view of part 3 of FIG. 2, and FIG. 4 is a graph showing the relationship between the engine speed and the ignition timing that is the knocking limit.

  As shown in FIG. 1, an in-line four-cylinder engine E for an automobile includes a cylinder block 11, a cylinder head 12 coupled to the upper surface of the cylinder block 11, a head cover 13 coupled to the upper surface of the cylinder head 12, and a cylinder. And an oil pan 14 coupled to the lower surface of the block 11. Four cylinder sleeves 16 are embedded in the upper part of the cylinder block 11 in which the crankcase 15 is integrally formed in the lower part, and a piston 17 slidably fitted to the cylinder sleeves 16 is connected to a connecting rod 18. Are connected to the crankshaft 19 via. The cylinder head 12 is formed with intake ports 21 and exhaust ports 22 that communicate with the combustion chambers 20. The intake valve holes and the exhaust valve holes are opened and closed by the intake valves 23 and the exhaust valves 24, respectively.

  The cylinder head 12 is provided with an intake camshaft 26 provided with intake cams 25 and an intake rocker arm 28 supported via an intake rocker arm shaft 27, and rotates in conjunction with the crankshaft 19. The intake valves 23 are driven by the intake rocker arms 28 that are swung by the intake cams 25. Further, the cylinder head 12 is provided with an exhaust camshaft 30 provided with exhaust cams 29 and an exhaust rocker arm 32 supported via an exhaust rocker arm shaft 31, and rotates in conjunction with the crankshaft 19. The exhaust valves 24 are driven by the exhaust rocker arms 32 that are swung by the exhaust cams 29.

  The cylinder block 11 is formed with a cylinder block side water jacket 33 so as to surround the four cylinder sleeves 16. The cylinder block side water jacket 33 communicates with the cylinder block side water jacket 33 through the opening of the gasket 34. A water jacket 35 is formed on the cylinder head 12.

  2 and 3 together, the deck surface 11a to which the cylinder block 11 is coupled to the cylinder head 12 via the gasket 34 surrounds the four cylinder sleeves 16. The cylinder block side water jacket 33 is opened. The shape of the opening 33a of the cylinder block side water jacket 33 is a shape in which four annular portions are partially overlapped in series, and the center of the outer peripheral wall of each annular portion coincides with the cylinder axis L. However, the center of the inner peripheral wall is shifted to the intake side of the engine E with respect to the cylinder axis L.

  Accordingly, the thickness between the cylinder bores 16a... And the cylinder block side water jacket 33 is such that the exhaust side thickness Te is small and the intake side thickness Ti is large. Accordingly, the width of the opening 33a of the cylinder block-side water jacket 33 is such that the exhaust-side width We is large and the intake-side width Wi is small (see portions A and B in FIGS. 3 and 1). .

  However, the thicknesses Te and Ti between the cylinder bores 16a... And the cylinder block side water jacket 33 differ only on the exhaust side and the intake side only in the vicinity of the opening 33a. Is gradually increased as the distance from the deck surface 11a increases, and finally the width We, Wi on the exhaust side and the intake side of the cylinder block-side water jacket 33 are the same at a portion more than a predetermined distance away from the deck surface 11a of the cylinder block 11. (See FIG. 1).

  Thus, the temperature of the deck surface 11a of the cylinder block 11 rises due to the heat generated by the combustion of the air-fuel mixture in the combustion chamber 20 with the operation of the engine E, but the temperature rise is not uniform on the intake side and the exhaust side. The temperature rise on the exhaust side where the exhaust ports 22 through which high-temperature exhaust gas flows is formed becomes significant. At this time, since the wall thickness between each cylinder bore 16a ... and the cylinder block side water jacket 33 surrounding it is set smaller on the exhaust side than on the intake side (Te <Ti), the cylinder bore 16a on the exhaust side is set. Is easily transmitted to the cylinder block-side water jacket 33, and the vicinity of the exhaust-side deck surface 11a, which tends to become high temperature, can be effectively cooled.

  In addition, since the width of the opening 33a to the deck surface 11a of the cylinder block side water jacket 33 is set larger on the exhaust side than on the intake side (We> Wi), the cylinder block side water jacket 33 is placed on the exhaust side. By increasing the flow rate of the flowing cooling water, it is possible to more effectively cool the vicinity of the deck surface 11a on the exhaust side that tends to become high temperature.

  As described above, the exhaust side having a relatively high temperature in the vicinity of the deck surface 11a of the cylinder block 11 is more actively cooled than the intake side having a relatively low temperature, so that the knocking resistance of the engine E is improved. Improvement, compression ratio increase, fuel consumption reduction, and output improvement.

  Further, the thickness between the cylinder bores 16a and the cylinder block side water jacket 33 is limited to the exhaust side in the vicinity of the deck surface 11a of the cylinder block 11, and the thickness on the intake side is ensured as usual. Therefore, it is possible to minimize the decrease in rigidity of the cylinder block 11 due to the reduced thickness on the exhaust side. In addition, the thickness of the exhaust side between the cylinder bores 16a... And the cylinder block side water jacket 33 gradually increases as the distance from the deck surface 1a increases.

  Further, on the exhaust side where the width of the cylinder block side water jacket 33 is large, the thickness between the cylinder bores 16a... And the cylinder block side water jacket 33 is small, and conversely, on the intake side where the width of the cylinder block side water jacket 33 is small, the cylinder bores 16a. Since the thickness between the cylinder block side water jackets 33 is large, it is possible to prevent only one of the exhaust side wall and the intake side side wall of the cylinder block 11 from becoming thick.

  FIG. 4 is a graph showing ignition timing at which knocking occurs at various engine speeds for both the example and the conventional example. From this graph, it can be seen that the ignition timing can be advanced (advanced) without causing knocking in the embodiment as compared with the conventional example, and thus the output of the engine E can be improved.

  Although the embodiments of the present invention have been described above, various design changes can be made without departing from the scope of the present invention.

  For example, although the four-cylinder engine E is illustrated in the embodiment, the present invention can be applied to an engine having an arbitrary number of cylinders including a single cylinder.

  The cylinder sleeves 16 of the engine E of the embodiment are independent from each other, but the present invention can also be applied to an engine having a so-called siamese type cylinder sleeve in which a plurality of cylinder sleeves are integrally connected. .

  The opening 33a of the cylinder block-side water jacket 33 of the embodiment has an outer periphery and an inner periphery that are both arcs, but they can be configured with an arbitrary contour other than the arc. Specifically, from the viewpoint of further increasing the rigidity of the cylinder block 11, the wall thickness may be reduced only around the exhaust valves 24, which are particularly likely to become hot.

  Further, in the engine E of the embodiment, the intake ports 21 and the exhaust ports 22 are disposed on the opposite sides across the cylinder axis L, but in the present invention, the intake ports 21 and the exhaust ports 22 are adjacent in the circumferential direction. The present invention can also be applied to engines that are arranged in the same manner.

Longitudinal sectional view of engine (cross sectional view taken along line 1-1 in FIG. 2) 2-2 line view of FIG. Part 3 enlarged view of FIG. Graph showing the relationship between engine speed and ignition timing that is the knock limit

Explanation of symbols

11 Cylinder block 11a Deck surface 16a Cylinder bore 33 Cylinder block side water jacket (water jacket)
Te Exhaust side thickness Ti Intake side thickness We Exhaust side width Wi Intake side width

Claims (3)

In the cooling structure of the open deck type cylinder block in which the water jacket (33) formed on the cylinder block (11) so as to surround the cylinder bore (16a) opens to the deck surface (11a) of the cylinder block (11).
The thickness between the cylinder bore (16a) and the water jacket (33) in the vicinity of the deck surface (11a) of the cylinder block (11) is smaller than the intake side thickness (Ti) on the exhaust side (Te). A cooling structure for an open deck type cylinder block, characterized in that   The width of the water jacket (33) in the vicinity of the deck surface (11a) of the cylinder block (11) is set such that the exhaust side width (We) is larger than the intake side width (Wi). The cooling structure of the open deck type cylinder block according to claim 1. The thickness (Te) on the exhaust side between the cylinder bore (16a) and the water jacket (33) in the vicinity of the deck surface (11a) of the cylinder block (11) is gradually increased as the distance from the deck surface (11a) increases. The open deck cylinder block cooling structure according to claim 1, wherein the structure is a cooling structure.

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