JP3527777B2 - Cylinder block structure - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder block structure for a vehicle engine, and more particularly, to a reduction in piston slap noise of a dry liner type open deck type cylinder block. About measures. 2. Description of the Related Art In general, in an engine, when a piston reciprocates in a cylinder during operation of the engine, a piston skirt portion is pressed against a cylinder wall by side thrust due to a tilt of a connecting rod. Therefore, when the direction of movement of the piston changes immediately after compression top dead center, the skirt portion collides with the cylinder wall opposite to that before compression top dead center due to the clearance between the cylinder and the piston, and the vibration is transmitted to the outside of the cylinder block. It is known that piston slap noise is generated. Therefore, as a measure to reduce the piston slap noise, a steel strut is added to the skirt portion of the piston to prevent an increase in clearance at low temperatures, or to offset the piston pin to the thrust side, and to provide an impact by a moment around the piston pin. And other methods have been proposed. However, according to these countermeasures, costs are increased, and disadvantages in durability, friction, and the like are caused. Here, as a structure of a cylinder block, for example, there is a structure in which a cylindrical liner made of, for example, cast iron is mounted in a dry liner type for each cylinder of an aluminum alloy cylinder. In this structure, the skirt portion of the piston collides with the liner during operation of the engine, and the vibration is transmitted to the outer wall of the cylinder via the inner wall of the cylinder to generate piston slap noise. Therefore, it is expected that the noise of the liner, which is a vibration source, can be reduced by suppressing the vibration by increasing the rigidity. There is also a dry liner type cylinder block of an open deck type in which a water jacket is further opened on the deck surface. In this open deck type, since the water jacket of the cylinder block opens to the deck surface, the liner expands to the water jacket side together with the cylinder inner wall by pressing when the head is fastened and deforms into an elliptical shape, resulting in oil consumption and blow-by. There is a possibility that the gas amount will increase. Therefore, it is expected that these problems can be solved by increasing the radial rigidity of the liner to improve the roundness. Conventionally, regarding the above cylinder block,
For example, there is a prior art in Japanese Patent Application Laid-Open No. 58-74851.
In this prior art, when the cylinder and the liner are made of an aluminum alloy, the depth of the water jacket is set to 0.2 to 0.5 of the liner length from the top of the cylinder block.
Liner ribs are provided from the inner wall of the crankcase to the liner. It is shown that the direct thermal deformation of the liner is received at the water jacket and the liner rib at two locations to reduce the thermal expansion of the bore and the elongation of the liner. . In the above-mentioned prior art, the cylinder and the liner are formed of the same aluminum alloy block, and the lower portion of the liner is exposed, and the liner rib is removed therefrom. Because of this structure, the cylinder block structure is different from that in which the liner is formed of a dry liner type using another material as in the present invention, so that it cannot be applied. According to this measure to increase the liner rigidity,
Since the water jacket around the liner is limited only to the upper part, there is a problem that the cooling performance by cooling water is reduced. In view of the foregoing, the present invention has been made to reduce the piston slap noise, oil consumption and the like in a dry liner type open deck type cylinder block by reliably increasing the rigidity in the liner radial direction. Aim. In order to achieve this object, a cylinder block structure according to claim 1 of the present invention comprises:
In each cylinder of the cylinder block, a cylindrical liner is integrally mounted by casting, and two water jackets curved to the liner side in substantially the entire cylinder arrangement direction around the liner are formed by opening on the deck surface. In the cylinder block structure, the inner wall of the cylinder is provided at each of opposed positions in the liner radial direction inside the two water jackets.
Ribs extending in the bore axis direction
At the end of the ribs, a gap through which cooling water can pass is provided, and the ribs have a predetermined width and a predetermined width from the deck surface.
U-shaped ribs formed in a U-shape to the depth and narrow width
With a rod-shaped rib that is formed in a rod shape from the jack surface to a predetermined depth
There is a U-shaped rib on the thrust side water jacket
Inside the liner orthogonal to the cylinder center line connecting the internal cylinders
Insert the rod-shaped rib on the anti-thrust side
At the position facing the U-shaped rib inside the water jacket
Integral with the cylinder inner and outer walls, respectively, in the bore axis direction
It is characterized by being provided in combination . According to the first aspect of the present invention, a liner is mounted in a dry liner type for each cylinder of the cylinder block, and two water jackets are provided around the liner in an open deck type. Formed. Then, at positions radially opposed to each other in the liner, the inner wall of the cylinder provided with the liner is integrally connected to the outer wall of the cylinder via a rib inside the water jacket, so that the rigidity of the liner in the radial direction is increased. Therefore, even if the skirt portion collides with the thrust side of the liner immediately after the compression top dead center of the piston during engine operation, the vibration of the liner is suppressed and the piston slap noise is reduced. In addition, when the head is tightened, the inner wall of the cylinder provided with the liner is prevented from being radially expanded and deformed by the ribs, so that the roundness of the liner is sufficiently ensured, and the oil consumption and blow-by gas amount are reduced. Is also reduced. Further, at the time of engine operation, in the two water jackets of the cylinder block, the cooling water easily flows through the gap at the end of the deck surface side through the gap at the end of the deck surface, and the cooling water causes the rib together with the liner and the cylinder. Cooled efficiently. Further, in the water jacket on the thrust side of the cylinder block, the inner wall and the outer wall of the cylinder are
The U-shaped ribs combine integrally in the circumferential direction and the bore axis direction to particularly increase the rigidity of the liner. For this reason, the vibration of the liner is reliably suppressed against the collision of the piston skirt during the operation of the engine, and the effect of reducing the piston slap noise is increased. Also, the U-shaped rib and the rod-shaped rib are arranged inside the two water jackets so as to face each other on the liner center line orthogonal to the cylinder center line connecting the cylinders most easily deformed. The liner is effectively prevented from deforming into an elliptical shape, and the liner is kept close to the true perfect circle. Embodiments of the present invention will be described below with reference to the drawings. 1 and 2, an overall outline of a case where the present invention is applied to a horizontally opposed engine as a vehicle engine will be described. Reference numeral 1 denotes a horizontally opposed engine, and 20 denotes a left and right divided cylinder block, for example, a left-side cylinder block viewed from the driver's seat, which is made of an aluminum alloy that is lightweight and excellent in cooling performance. It is an integral type of the wheel housing 23. Liner 24
Is a material different from the cylinder block 20, for example, heat resistance,
It is made of cast iron having excellent wear resistance and the like, and the bore 25 is formed in a cylindrical shape having a predetermined size. Then, a liner 24 is a dry liner type cylinder block in which a liner 24 is integrally mounted on each cylinder of the cylinder 21 by aluminum die casting. In the cylinder 21, two water jackets 26, 27 curved substantially over the entire area above and below the liner 24 in the cylinder arrangement direction are formed, and these water jackets 26, 27 are formed in an open-deck type opened to the deck surface 21c. Is done. Therefore, an inner wall 21a having a liner 24 inside the water jackets 26 and 27 of the cylinder 21 and an outer wall 21b outside the water jackets 26 and 27 are formed. Here, in the left cylinder block 20, the upper part of the liner 24, that is, the upper water jacket 26, is located immediately after the compression top dead center due to the inclination of the connecting rod 5 accompanying the engine rotation direction (left rotation as viewed from the driver's seat). On the thrust side, the lower part of the liner 24, that is, the lower water jacket 27 is on the anti-thrust side. When two cylinders are provided on the cylinder center line X of one cylinder block 20 in the illustrated four-cylinder engine, the upper and lower water jackets 26 and 27 are continuously curved across the two cylinders. A piston 3 having a piston ring 2a and an oil ring 2b is reciprocally inserted into a bore 25 of the liner 24. The piston 3 is connected to the connecting rod 5 by a pin 4 and connected to the crankshaft. Is done. The cylinder head 10 made of aluminum alloy is provided on the deck surface of the cylinder block 20 via a gasket 7.
Is concluded. The liner 24 in the cylinder head 10
The combustion chamber 11 is provided at a location facing the bore 25 of the intake valve 12 and the exhaust valve 13 and the exhaust valve 13 provided in the combustion chamber 11.
Is opened and closed by a SOHC type valve train 14. In the cylinder head 10, a water jacket 15 is formed at a position opposed to the upper and lower water jackets 26, 27 of the cylinder block 20, and these water jackets 26, 27, 15 communicate directly. As the cooling device 16, the cylinder block 2
The inflow passage 17 for the cooling water W is communicated with the lower water jacket 27 of the cylinder No. 0, and the discharge passage 18 thereof is communicated with the upper water jacket 26. Then, the cooling water W flows into the lower water jacket 27 of the cylinder block 20,
The entire area of the lower water jacket 27 flows into the water jacket 15 of the cylinder head 10, then flows again into the entire area of the upper water jacket 26 of the cylinder block 20, and flows through the water jacket 26 to be discharged. . Referring to FIGS. 1 to 4, measures for reducing piston slap noise and the like will be described. First, in the cylinder block 20, a U-shaped rib 30 is provided inside the upper water jacket 26 on the thrust side, and a rod-shaped rib 31 is provided inside the lower water jacket 27 on the opposite thrust side. These ribs 30 and 31 are
Are arranged opposite to each other at a position where deformation is most likely in the radial direction, that is, on a liner center line Y orthogonal to the cylinder center line X connecting the cylinders. The U-shaped rib 30 has a predetermined width as shown in FIGS. 3 and 4, and is formed in a U-shape by removing the inside thickness. A U-shaped rib 30 integrally connects the cylinder inner wall 21a and the outer wall 21b in a relatively wide range in the circumferential direction on the liner center line Y inside the upper water jacket 26 and in the bore axis Z direction from the crank chamber side. As a result, deformation of the cylinder inner wall 21a can be effectively prevented, and the rigidity of the liner 24 on the thrust side can be particularly increased. Further, a gap 32 having a predetermined depth through which the cooling water W can pass is provided between the end 30a of the U-shaped rib 30 and the deck surface 21c, and the flow of the cooling water W is ensured. The bar-shaped rib 31 is formed in a narrow bar shape as shown in FIG.
At a position facing the U-shaped rib 30, the cylinder inner wall 2 is formed in the same manner as the U-shaped rib 30 in the direction of the bore axis Z from the crank chamber side.
1a and the outer wall 21b are provided so as to be integrally connected. This effectively prevents deformation of the cylinder inner wall 21a and increases the rigidity of the liner 24 on the side opposite to the thrust. Similarly, a gap 32 having a predetermined depth is provided between the end 31a of the rod-shaped rib 31 and the deck surface 21c.
Is provided. Here, the optimum width L1 of the U-shaped rib 30 is
For example, L1 = 20 mm, and the optimal depth L2 of the gap 32 between the ribs 30, 31 is, for example, L2 = 25 mm. In the right cylinder block of the horizontally opposed engine 1 of the present embodiment, the relationship between the thrust side and the anti-thrust side of the liner is opposite to that of the left cylinder described above. A U-shaped rib and a bar-shaped rib on the half thrust side. Next, the operation of this embodiment will be described. First, a liner 24 is mounted on each cylinder of the cylinder 21 in a dry liner type, and two water jackets 26 and 27 are formed in an open deck type around the liner 24. A gasket 7 is mounted on a deck surface 21 c of the cylinder block 20. The cylinder head 10 is fastened and assembled. At the time of this head tightening, the cylinder inner wall 21a provided with the liner 24 is pressed in the radial direction by the cylinder head 10, so that the upper and lower water jacket side portions that are easily deformed are enlarged in diameter in this case. The U-shaped rib 30 and the rod-shaped rib 31 directly and effectively prevent the vertical expansion of the cylinder inner wall 21a on the liner center line Y at the position where the inside of the water jackets 26 and 27 is most easily deformed. Therefore, the liner 24 is prevented from being expanded in the vertical direction and deformed into an elliptical shape, and a good roundness is maintained while maintaining a state close to an original perfect circle. On the other hand, during operation of the engine, the piston 3 moves the bore 25 of the liner 24 of the cylinder 21 into the connecting rod 5.
Reciprocate while tilting up and down. At this time, piston 3
Immediately after the compression top dead center, the piston skirt 3a collides with the thrust side of the liner 24 due to a change in the movement direction of the piston 3 each time. In this case, the cylinder inner wall 21a
And the outer wall 21b are integrally coupled in the circumferential direction and the bore axis Z direction by the U-shaped rib 30, and particularly the liner rigidity is increased, so that the vibration of the liner 24 is ensured against the collision of the piston skirt portion 3a. Is suppressed. Therefore, the liner 24
Is hardly transmitted to the outer wall 21b side, and the piston slap noise is reduced. Further, the improvement in the roundness of the liner 24 makes it possible to reduce the piston clearance, and the piston ring 2 follows the liner 24 satisfactorily, causing oil leakage from the crank chamber 8 and blow-by gas leakage from the combustion chamber 11. Is reduced. During operation of the engine, cooling water W flows into the lower water jacket 27 of the cylinder block 20. The cooling water W passes through the gap 32 where the rod-shaped rib 31 is present, and the width of the lower water jacket 27 is reduced. The cooling water W easily flows over the entire area in the cylinder arrangement direction on the side opposite to the thrust side of the liner 24 and the cylinder 21 with the cooling water W. Thereafter, the cooling water W of the lower water jacket 27 flows into the water jacket 15 of the cylinder head 10 and flows through the inside thereof, and the combustion chamber 11 and the like are cooled. The cooling water W in the water jacket 15 of the cylinder head 10 flows into the upper water jacket 26 of the cylinder block 20 again. Again, U
The portion where the U-shaped rib 30 exists passes through the gap 32 and easily flows to the entire region in the width direction of the upper water jacket 26, and the cooling water W makes the liner 24 and substantially the entire region in the cylinder arrangement direction on the thrust side of the cylinder 21 efficient. Cools well. In this case, the cooling water W is in direct contact with the U-shaped ribs 30 and the rod-shaped ribs 31 to be effectively cooled. Referring to FIG. 5, another embodiment of the present invention will be described. In this embodiment, the cylinder inner wall 35 is formed to have a lower wall thickness in the center line Y direction, and the upper and lower water jackets 26 and 27 are also formed in the cylinder inner wall 35.
Similarly, the U-shaped rib 30 and the bar-shaped rib 31 can be provided, and the same effect can be obtained. The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. If the cylinder block has a dry liner type and an open deck type structure, it can be similarly applied to vertical and V-type engines other than the horizontally opposed engine. The cylinder and liner can also be applied to the block integrated type made of the same material. As described above, in the cylinder block structure according to the first aspect of the present invention, in the dry liner type open deck type cylinder block, the liner radial direction is formed inside the two water jackets. The ribs are integrally connected to the inner and outer walls of the cylinder and are provided in the bore axis direction at the opposing positions of the cylinders. The radial rigidity of the liner can be improved while doing so. Therefore, the vibration when the skirt portion collides with the thrust side of the liner immediately after the compression top dead center of the piston is suppressed, and the piston slap noise can be reduced. Further, deformation of the liner at the time of head tightening can be prevented, roundness can be improved, and oil consumption and blow-by gas can be reduced. Further , the rib is a U-shaped rib having a predetermined width and formed in a U-shape from the deck surface to a predetermined depth, and a rod-shaped rib having a narrow width and formed in a bar shape from the deck surface to a predetermined depth. The U-shaped rib faces the U-shaped rib inside the water jacket on the anti-thrust side in the bore axis direction on the liner center line perpendicular to the cylinder center line connecting the cylinders inside the water jacket on the thrust side. In this case, the U-shaped ribs can effectively suppress the vibration of the liner, and the piston slap noise reduction effect is large. In addition, the U-shaped rib and the rod-shaped rib can directly and effectively prevent the deformation of the liner when tightening the head. In addition, since the inside of the U-shaped rib is thinned, the weight of the engine can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing an embodiment of a cylinder block structure according to the present invention. FIG. 2 is a side view from the head side of the cylinder block. FIG. 3 is a sectional view taken along line AA of FIG. 1; FIG. 4 is a perspective view of a main part of the embodiment. FIG. 5 is a sectional view of a main part showing another embodiment of a cylinder block structure. [Description of Signs] 20 Cylinder block 21 Cylinder 21a Inner wall 21b Outer wall 21c Deck surface 24 Liner 26, 27 Water jacket 30 U-shaped rib 31 Bar-shaped rib 32 Gap

Claims (1)

(57) [Claim 1] A cylindrical liner is integrally mounted on each cylinder of a cylinder block by casting, and is provided on the liner side in substantially the entire cylinder arrangement direction around the liner. In a cylinder block structure in which two curved water jackets are formed on the deck surface , the cylinder inner wall and the outer wall are integrally connected to the inside of the two water jackets at opposing positions in the liner radial direction.
Ribs extending in the bore axis direction are provided together, and a gap through which cooling water can pass is provided on the end side of the rib, and the rib has a predetermined width and a predetermined depth from the deck surface.
U-shaped ribs formed in a U-shape, and a deck surface with a narrow width
From the U-shaped rib to the thrust-side water jacket.
Liner center perpendicular to the cylinder center line connecting the cylinders
On the line, in the bore axis direction, insert the rod-shaped rib into the water jacket on the opposite thrust side.
At the position facing the U-shaped rib of the
A cylinder block structure characterized by being integrally provided on the inner and outer walls of the cylinder.