JPH0814098A - Cylinder block structure - Google Patents

Abstract

PURPOSE:To reduce the generation of piston slap noise through the reliable increase of rigidity in a radial direction of a line and to reduce an oil consumption amount, in a dry liner type and open deck type cylinder block. CONSTITUTION:Formation of a cylinder block 20 is such that a cylindrical liner 24 is internally chilled and integrally mounted on each cylinder of a cylinder block 20 and two water jackets 26 and 27 curved to the liner 24 side approximately throughout the cylinder arrangement direction of the periphery of the liner 24 is formed in such a state to be opened to a deck surface 21c. Ribs 30 and 31 positioned facing each other in the radial direction of the radial direction of the liner in the two water jackets 26 and 27 are formed in the direction of a bore axis Z in such a state to be coupled integrally with a cylinder inner wall 21a and an outer wall 21b. A gap 32 through which cooling water W passes is provided between the end part sides of the ribs 30 and 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle engine cylinder block structure, and more particularly to a measure for reducing piston slap noise and the like of a dry liner type open deck type cylinder block.

[0002]

2. Description of the Related Art Generally, in an engine, a piston skirt portion is pressed against a cylinder wall by a side thrust due to an inclination of a connecting rod when a piston reciprocates in a cylinder during engine operation. Therefore, if the movement direction of the piston changes immediately after top dead center of compression, the clearance between the cylinder and piston causes the skirt to collide with the cylinder wall on the side opposite to that before top dead center of compression, and the vibration is transmitted to the outside of the cylinder block. It is known to generate piston slap noise.

Therefore, as a measure for reducing the piston slap noise, steel struts are added to the skirt of the piston to prevent an increase in clearance at low temperatures, and the piston pin is offset to the thrust side so that the moment around the piston pin causes an impact. Have been proposed. However, these measures increase the cost and are disadvantageous in terms of durability and friction.

As a structure of the cylinder block, there is a dry liner type cylinder liner made of cast iron, for example, for each cylinder of an aluminum alloy cylinder. In this structure, the skirt portion of the piston collides with the liner during engine operation, and its vibration is transmitted to the outer wall of the cylinder through the inner wall of the cylinder to generate piston slap noise. Therefore, it is expected that the noise can be reduced by suppressing the vibration of the liner, which is the vibration source, by increasing its rigidity.

There is also a dry liner type cylinder block, and an open deck type cylinder block in which a water jacket is opened on the deck surface. With this open deck type, the water jacket of the cylinder block opens on the deck surface, so the liner, along with the cylinder inner wall, expands in diameter toward the water jacket side and deforms into an elliptical shape due to pressure when the head is fastened, resulting in oil consumption and blow-by. This may lead to an increase in gas amount. 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 of Japanese Patent Laid-Open No. 58-74851.
In this prior art, when the cylinder and the liner are made of aluminum alloy, the depth of the water jacket is set to 0.2 to 0.5 of the liner length from the upper end of the cylinder block.
Double the liner rib from the inner wall of the crankcase to the liner. It has been shown that direct thermal deformation of the liner is received at two points of the water jacket and the liner rib to reduce the thermal expansion of the bore and the expansion of the liner, and the cooling of the liner is performed by the water of the water jacket and the heat radiation of the liner rib. .

[0007]

By the way, in the above-mentioned prior art, the structure is such that the cylinder and the liner are made of the same aluminum alloy block, and the lower part of the liner is exposed and the liner rib is externally attached thereto. Therefore, the cylinder block structure is different from that of the dry liner type in which the liner is made of another material as in the present invention. In addition, 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 the cooling water is lowered.

In view of the above points, the present invention is intended to reliably increase the rigidity in the radial direction of a liner in a dry liner type open deck type cylinder block to reduce piston slap noise, oil consumption, and the like. To aim.

[0009]

In order to achieve this object, a cylinder block structure according to claim 1 of the present invention comprises:
For each cylinder of the cylinder block, a cylindrical liner is integrally mounted around the cylinder, and two water jackets that are curved toward the liner are formed on the deck surface. In the cylinder block structure described above, ribs are provided inside the two water jackets at opposing positions in the radial direction of the liner so as to be integrally coupled to the inner wall and the outer wall of the cylinder in the axial direction of the bore, and the ribs are cooled on the end side. It is characterized by providing a gap through which water can pass.

The cylinder block structure according to claim 2 is
The rib has a specified width and U from the deck surface to a specified depth.
It is a U-shaped rib formed in a U-shape and a rod-shaped rib formed in a narrow width from the deck surface to a predetermined depth, and the U-shaped rib is a center line connecting each cylinder inside the thrust side water jacket. A rod-shaped rib may be provided integrally with the cylinder inner wall and the outer wall in the bore axial direction on the orthogonal liner center line at a position facing the U-shaped rib inside the water jacket on the anti-thrust side in the bore axial direction. Characterize.

[0011]

Therefore, according to the first aspect of the present invention, the liner is mounted in each cylinder of the cylinder block in a dry liner type, and two water jackets are formed in an open deck type around the liner. Then, at the radially opposite positions of the liner, the cylinder inner wall provided with the liner is integrally connected to the cylinder outer wall via the rib inside the water jacket, thereby increasing the radial rigidity of the liner. Therefore, even if the skirt collides with the thrust side of the liner immediately after the top dead center of compression of the piston during engine operation, vibration of the liner is suppressed and piston slap noise is reduced.

Further, 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. Therefore, the roundness of the liner is ensured to be good, and the oil consumption and blow-by gas amount can be secured. Is also reduced. Further, when the engine is in operation, the cooling water in the two water jackets of the cylinder block easily flows through the gap at the end on the deck surface side to the entire area where there are ribs, and this cooling water causes the ribs along with the liner and the cylinder to be removed. Cools efficiently.

According to a second aspect of the present invention, in the thrust jacket water jacket of the cylinder block, the inner wall and the outer wall of the cylinder are integrally connected in the circumferential direction and the bore axial direction by the U-shaped rib, so that the rigidity of the liner is particularly increased. . Therefore, the vibration of the liner is reliably suppressed against the collision of the piston skirt portion during engine operation, and the effect of reducing the piston slap noise is increased. Further, 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 Linda center line connecting the cylinders most easily deformed. Deformation of the liner into an elliptical shape is effectively prevented, and the liner is maintained in a state close to the original perfect circle.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1 and FIG. 2, an overall outline of the case where the present invention is applied to a horizontally opposed engine as a vehicle engine will be described. Reference numeral 1 is a horizontally opposed engine, and 20 is a cylinder block on the left side as viewed from the driver's seat, which is divided into two parts on the left and right sides. The cylinder block is made of an aluminum alloy that is lightweight and has excellent cooling properties. It is an integral type of the wheel housing 23. Liner 24
Is a material different from that of 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 into a cylindrical shape having a predetermined size. A liner 24 for each cylinder of the cylinder 21 is a dry liner type cylinder block that is integrally mounted by aluminum die-casting around the casting.

Further, in the cylinder 21, two water jackets 26, 27 which are curved are formed substantially in the entire area above and below the liner 24 in the cylinder arrangement direction, and these water jackets 26, 27 are formed as an open deck type opening to the deck surface 21c. To be done. Therefore, the inner wall 21 a having the liner 24 is formed inside the water jackets 26 and 27 of the cylinder 21, and the outer wall 21 b is formed outside the water jackets 26 and 27.

In the cylinder block 20 on the left side, the upper portion 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 caused by the engine rotation direction (left rotation when viewed from the driver's seat). It is on the thrust side, and the lower portion 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 over the two cylinders.

A piston 3 provided with 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 a connecting rod 5 by a pin 4 and connected to the crankshaft side. To be done.

A cylinder head 10 made of an aluminum alloy is provided on the deck surface of the cylinder block 20 through a gasket 7.
Is concluded. The liner 24 in the cylinder head 10
The combustion chamber 11 is provided at a position facing the bore 25 of the intake valve 12 and the exhaust valve 13 provided in the combustion chamber 11.
Is opened and closed by the SOHC valve operating mechanism 14. Further, in the cylinder head 10, a water jacket 15 is formed at a position facing the water jackets 26, 27 at the upper and lower portions of the cylinder block 20, and these water jackets 26, 27, 15 are in direct communication with each other.

As the cooling device 16, the cylinder block 2
An inflow passage 17 for the cooling water W is connected to the lower water jacket 27 of 0, and an exhaust passage 18 is connected to 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 the entire area of the upper water jacket 26 of the cylinder block 20 again, and then flows through the water jacket 26 and is discharged. .

A measure for reducing piston slap noise and the like will be described with reference to FIGS. First, in the cylinder block 20, a U-shaped rib 30 is provided inside the thrust-side upper water jacket 26, and a rod-shaped rib 31 is provided inside the anti-thrust-side lower water jacket 27. These ribs 30 and 31 are provided on the liner 24.
Are opposed to each other at a position where they are most easily deformed in the radial direction, that is, on a liner center line Y orthogonal to a 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 thinning the inside. The U-shaped rib 30 integrally joins the cylinder inner wall 21a and the outer wall 21b on the liner center line Y inside the upper water jacket 26 in a relatively wide range in the circumferential direction and in the bore axis Z direction from the crank chamber side. The cylinder inner wall 21a is effectively prevented from being deformed, 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 portion 30a of the U-shaped rib 30 and the deck surface 21c to ensure the flow of the cooling water W.

The rod-shaped rib 31 is formed in a narrow rod shape as shown in FIG.
Similar to the U-shaped rib 30, the cylinder inner wall 2 is located at a position facing the U-shaped rib 30 in the direction of the bore axis Z from the crank chamber side.
It is provided so that 1a and the outer wall 21b are integrally connected. This makes it possible to effectively prevent the deformation of the cylinder inner wall 21a and increase the rigidity of the liner 24 on the anti-thrust side. Similarly, between the end 31a of the rod-shaped rib 31 and the deck surface 21c, a gap 32 of a predetermined depth is formed.
Is provided.

Here, the optimum width L1 of the U-shaped rib 30 is
For example, L1 = 20 mm, and the optimum depth L2 of the gap 32 between the ribs 30 and 31 is, for example, L2 = 25 mm. In the cylinder block on the right side 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 side cylinder described above. Is provided with a U-shaped rib and a rod-shaped rib on the half thrust side.

Next, the operation of this embodiment will be described. First, the liner 24 is attached to each cylinder of the cylinder 21 in a dry liner type, two water jackets 26 and 27 are formed in an open deck type around the liner 24, and the gasket 7 is attached to the deck surface 21c of the cylinder block 20. The cylinder head 10 is fastened and assembled. At the time of tightening the head, the cylinder head 10 radially presses the cylinder inner wall 21a having the liner 24, so that the upper and lower water jacket side portions, which are easily deformed, are vertically expanded. Further, on the liner center line Y at the most easily deformable position inside the water jackets 26, 27, the U-shaped rib 30 and the rod-shaped rib 31 directly and effectively prevent the vertical expansion of the cylinder inner wall 21a. Therefore, the liner 24 is prevented from being expanded in diameter in the vertical direction to be deformed into an elliptical shape, and the roundness is kept good while maintaining a state close to the original roundness.

On the other hand, when the engine is operating, the piston 3 moves the bore 25 of the liner 24 of the cylinder 21 into the connecting rod 5
It moves back and forth while inclining up and down. At this time piston 3
Immediately after the compression top dead center, the piston skirt portion 3a collides with the thrust side of the liner 24 due to the change in the movement direction of the piston 3 each time. In this case, the cylinder inner wall 21a
Since the outer wall 21b and the outer wall 21b are integrally connected to each other in the circumferential direction and the bore axis Z direction by the U-shaped rib 30, the liner rigidity is particularly increased, so that the vibration of the liner 24 against the collision of the piston skirt portion 3a is ensured. Suppressed. Therefore liner 24
Vibration is less likely to be transmitted to the outer wall 21b side, and piston slap noise is reduced. Further, since the circularity of the liner 24 is improved, the piston clearance can be reduced, and the piston ring 2 follows the liner 24 well, so that the oil leaks from the crank chamber 8 and the blow-by gas leaks from the combustion chamber 11. Is less.

When the engine is in operation, the cooling water W flows into the lower water jacket 27 of the cylinder block 20. The cooling water W passes through the gap 32 at the portion having the rod-shaped rib 31 and the width of the lower water jacket 27. The cooling water W efficiently cools the liner 24 and the substantially thrust cylinder side of the cylinder 21 in the cylinder arrangement direction. After that, the cooling water W of the lower water jacket 27 flows into the water jacket 15 of the cylinder head 10 and flows inside the water jacket 15, and the combustion chamber 11 and the like are cooled.

Then, the cooling water W of the water jacket 15 of the cylinder head 10 flows into the upper water jacket 26 of the cylinder block 20 again. In this case also U
A portion having the letter-shaped rib 30 easily passes through the gap 32 and flows in the entire region in the width direction of the upper water jacket 26, and the cooling water W makes the entire region in the cylinder arrangement direction on the thrust side of the liner 24 and the cylinder 21 efficient. Well cooled. In this case, the U-shaped rib 30 and the rod-shaped rib 31 are in direct contact with the cooling water W and are effectively cooled.

Another embodiment of the present invention will be described with reference to FIG. In this embodiment, the cylinder inner wall 35 is formed to have a lower wall thickness in the direction of the center line Y, and the cylinder inner wall 35 also has upper and lower water jackets 26, 27.
Similarly, the U-shaped rib 30 and the rod-shaped rib 31 can be provided, and the same effect can be obtained. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

If the cylinder block is a dry liner type open deck type structure, it can be similarly applied to vertical type and V type engines other than the horizontally opposed type engine. It is also applicable to the block integrated type in which the cylinder and the liner are made of the same material.

[0030]

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 two water jackets are opposed to each other in the radial direction of the liner. At each position, ribs are integrally connected to the inner wall and the outer wall of the cylinder and are provided in the axial direction of the bore, and a gap through which cooling water can pass is provided at the end side of these ribs, so that the liner is secured while ensuring the cooling performance. The radial rigidity of can be improved. Therefore, the vibration when the skirt collides with the thrust side of the liner immediately after the top dead center of compression of the piston can be suppressed, and the piston slap noise can be reduced. It is also possible to prevent deformation of the liner when tightening the head, improve the roundness, and reduce the oil consumption and blow-by gas amount.

In the cylinder block structure according to the second aspect, the rib has a U-shaped rib having a predetermined width and formed in a U shape from the deck surface to a predetermined depth, and a narrow width from the deck surface to a predetermined depth. It is a rod-shaped rib formed in a rod shape,
A position where 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 orthogonal to the cylinder center line connecting the cylinders inside the thrust side water jacket. Since the cylinder inner wall and the outer wall are integrally connected to each other in the bore axis direction, the U-shaped rib can effectively suppress the vibration of the liner, and the piston slap noise reduction effect is large. Further, the U-shaped rib and the rod-shaped rib can directly and effectively prevent the deformation of the liner when the head is tightened. Further, since the U-shaped rib is thinned inside, the weight of the engine can be reduced.

[Brief description of 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 of the cylinder block from the head side.

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 the cylinder block structure.

[Explanation of symbols]

 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 Rod-shaped Rib 32 Gap

Claims (2)

[Claims] 1. A cylinder-shaped liner is integrally mounted around each cylinder of a cylinder block by casting, and two water jackets curved toward the liner around the liner are arranged on the deck surface. In the cylinder block structure formed by opening to the inner side of the two water jackets, ribs are respectively provided in opposing positions in the liner radial direction inside the two water jackets, integrally provided on the cylinder inner wall and the outer wall, and provided in the bore axial direction. A cylinder block structure characterized in that a gap through which cooling water can pass is provided on the end side. 2. The U-shaped rib, which has a predetermined width and is formed in a U shape from a deck surface to a predetermined depth, and a rod-shaped rib, which is formed in a rod shape with a narrow width from the deck surface to a predetermined depth. The U-shaped rib and the U-shaped rib inside the water jacket on the anti-thrust side are parallel to the bore axial direction on the liner center line orthogonal to the cylinder center line connecting the cylinders inside the thrust side water jacket. 2. The cylinder block structure according to claim 1, wherein the cylinder block structure is integrally connected to the cylinder inner wall and the cylinder outer wall at opposing positions in the bore axis direction.