JPS59231261A - Cylinder bore construction for connecting rod- incorporated piston - Google Patents

Abstract

PURPOSE:To prevent knocking by forming the top end part of a clyinder bore, which houses a connecting rod-incorporated piston having a spherical outer periphery, into an upwardly tapering spherical face so as to match the spherical configuration of the outer periphery of said piston when it is positioned at the top dead center. CONSTITUTION:A connecting rod-incorporated piston 13 is slidably and reciprocatingly installed in a cylinder bore 12. The piston 13 consists of a piston part 13a having a spherical outer configuration and disirably having a concave top surface, and a connecting rod part 13b constructed in an integrated form with the piston part 13a. On the top end part of a cylinder bore 12 is provided an upwardly tapering spherical configuration part 17 having an inner peripheral surface configuration which is matched with the spherical configuration of the outer periphery of the connecting rod-incorporated piston 13 which is positioned at the top dead center of piston. This eliminates the generation of a dead volume between the both, resulting in good combustion and reducing knocking.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylinder bore structure for an engine or a pump that uses a connecting rod-integrated piston having a spherical outer peripheral shape.

Conventionally, the piston and connecting rod structures have been formed separately and connected via a piston pin, but this structure has a so-called compression hide, which is the height from the piston pin to the top surface of the piston. However, there is a problem in that there is a limit to how much the device can be made smaller and lighter.

In order to solve this problem, the applicant of this patent has previously proposed the first patent application.
Connect the piston 1 to the connecting rod 2 as shown in the figure.
The outer circumferential surface 3 of the piston portion 1 of the piston 1 formed integrally with the connecting rod 2 is formed into a spherical surface, and the outer circumferential surface 3 always has a cylindrical inner surface regardless of the rocking of the piston 1. A piston with an integrated connecting rod has been proposed which is brought into sliding contact with the cylinder bore 4 (Patent Application No. 58-26372, filed on February 21, 1988).

However, in the structure proposed above, as shown in FIG. Configure volume 5. This dead volume 5 increases the S-V ratio of the combustion chamber 6, making it difficult for flame to enter, increasing the amount of unburned hydrocarbon components in the exhaust gas, and being disadvantageous to ensuring the compression ratio of the combustion chamber 6. There are various problems such as making it easier to cause knocking.

The present invention minimizes the dead volume in the combustion chamber formed between the upper end of the cylinder bore and the outer circumferential surface of the piston in a cylinder bore structure in which a piston with a spherical outer peripheral shape is installed, thereby eliminating the above-mentioned problems caused by the dead volume. The purpose is to

In order to achieve this object, in the cylinder bore structure of the present invention, the upper end of the cylinder bore, in which the connecting rod-integrated piston having a spherical outer peripheral shape is slidably and reciprocally movable, is located at the top dead center position. It is formed into a spherical shape that tapers upward so as to follow the spherical shape of the outer circumference of the piston when it is in the position.

In such a cylinder bore structure, the space between the outer periphery of the screw ring and the cylinder bore is filled by the protruding spherical portion of the cylinder bore, thereby eliminating dead volume.

Therefore, the problem caused by the dead volume is eliminated, and knocking is prevented and unburned components in the exhaust gas are reduced.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a cylinder bore structure for a piston with an integrated connecting rod according to the present invention will be described below with reference to the drawings.

FIG. 2 shows a cylinder bore structure for a piston with an integrated connecting rod according to a first embodiment of the present invention.

In the figure, 10 is a cylinder head, 11 is a cylinder block, and 12 is a cylinder bore consisting of a straight cylindrical surface except for the upper end.

A connecting rod integrated piston 13 in which a piston and a connecting rod are integrated is housed in the cylinder bore 12 so as to be slidable and reciprocating. The connecting rod integrated piston 13 is composed of a piston portion 13a having a spherical outer circumference and preferably a concave upper surface, and a connecting rod portion 13b that is formed integrally with the piston portion 13a and extends downward. , the piston portion 13a is a piston portion main body 138
' and a piston ring 14 fitted around the outer periphery of the piston body 4-13a-. The shape of the outer circumferential surface of the piston main body 138' consists of a convex portion and a concave portion extending over the entire outer circumference.

A spherical ring-shaped piston ring 14 with an outer peripheral surface having a radius R is fitted onto the outer periphery of the piston main body 13a-. This radius R has substantially the same dimension as the inner radius of the cylinder bore 12. Therefore, the outer peripheral surface of the piston ring 14 is in contact with the inner surface of the cylinder pore 12 over the entire circumference. Although not shown, the piston ring 14 has an abutment cut in one place in the circumferential direction, and the diameter of the piston ring 14 is expanded by widening the abutment to make use of the elasticity of the piston ring. , is fitted into the outer periphery of the piston body 138'. The abutment may extend diagonally in a straight line or may extend in a zigzag shape. Then, the piston part main body 13 of the piston ring 14
The inner surface shape of the fitting part with 8' is similar to that of the piston body 13.
The piston ring 14 is formed in a shape that wraps around a convex portion on the outer periphery of the piston body 13a-, and is fixed to the piston body 13a- by being fitted onto the outer periphery of the piston body 13a-. Further, the piston ring 14 is fitted to the screw 1 to the main body 13a so as to be rotatable in the circumferential direction. is being forced to.

Note that the structure for the connecting rod-integrated piston may be a structure as shown in FIGS. 3 to 6. In the example shown in FIG. 3, the number of projections and depressions in the fitting between the piston ring 14 and the piston body 13a' is increased, and the contact area becomes large. movement is large, which is advantageous for cooling. In the example shown in FIG. 4, a cooling oil passage 15 is provided between the piston ring 14 and the piston main body 13a', and oil is led from an oil passage 16 formed in the connecting rod part 13b for forced cooling. This is advantageous for cooling the piston ring 14. In the example shown in FIG. 5, the piston ring 14 is composed of a thin plate member 14a that contacts the inner periphery of the cylinder bore 12 and an elastic member 14b that urges it to expand outward. This has the advantage that each member can be constructed from suitable materials. The example shown in FIG. 6 is a piston in which the piston ring 14 and the piston body 13a' are integrated, which has the advantage of simplifying the structure.

The upper end of the cylinder bore 12 is provided with a spherical portion 17 whose inner circumferential surface is tapered upward and whose inner peripheral surface follows the spherical shape of the outer periphery of the connecting rod-integrated piston 13 at the piston top dead center position. In the first embodiment, this spherical portion 17 is formed on the inner periphery of a collar 18 that is separate from the cylinder head 10 and cylinder block 11. The collar 18 has a cylindrical outer circumference and is fitted into a stepped cylindrical recess 19 formed at the upper end of the cylinder block 11, and the upper end of the collar 18 is in contact with the lower surface of the cylinder head 10. A gasket 20 interposed between the cylinder head 10 and the cylinder block 11 is located on the outer peripheral side of the collar 18 and is shielded from the combustion chamber 21 by the collar 18.

The lower part of the connecting rod part 13b is formed in the shape of a normal large end, and the bearing cap 2
2. It is rotatably connected to a crankshaft 24 by a mounting bolt 23. A balance weight 25 is provided on the crankshaft 24 to balance the mass of rotation.

FIG. 7 shows the structure of the upper end of the cylinder bore and its vicinity in a second embodiment of the present invention. In this example,
Collar 18 is cylinder head 10 and cylinder block 1
1 and 2. A stepped cylindrical recess 19 is formed in the cylinder block 11 at the upper end of the cylinder pore 12, and a stepped cylindrical recess 8-26 is formed in the cylinder head 10 above the stepped cylindrical recess 19. The collar 18 is fitted circumferentially into these stepped cylindrical recesses 19.26. This fitting ensures positioning accuracy between the cylinder block 11 and the cylinder head 10. On the inner periphery of the collar 18, there is a spherical shaped part 17 shaped to follow the outer peripheral surface of the connecting rod integrated piston 13 when the piston reaches the top dead center position.
is provided. In addition, the lower end position of the collar 18 is located above the contact line S between the outer periphery of the piston 13 integrated with the connecting rod, that is, the outer periphery of the piston ring 14, and the cylinder bore 12 at the piston top dead center position, so that the sliding seal can be completed. It's being measured. In this embodiment as well, the gasket 20 is located outside the collar 18.

The configuration is similar to that of the first embodiment, and corresponding parts are given the same reference numerals as those of the first embodiment.

FIG. 8 shows the structure of the upper end of the cylinder bore and its vicinity in a third embodiment of the present invention. In this example,
A spherical portion 17 at the upper end of the cylinder bore 12 is formed on the cylinder block 11 side. In addition, the outer periphery of the connecting rod integrated piston 13 and the cylinder bore 12
The contact line S at the top dead center position of the screw 1 is located below the upper end of the cylinder block 11 to ensure a perfect sliding seal. Further, in FIG. 8, D is a small rearance for preventing collision between the piston 13 integrated with the connecting rod and the spherical portion 17 of the cylinder bore 12, and 27 is the squish portion of the combustion chamber.

Next, the operation of each embodiment of the apparatus of the present invention constructed as described above will be explained.

By adopting a piston with an integrated connecting rod, the compression hide has been reduced, making the engine smaller and lighter.

Since the outer circumference of the connecting rod-integrated piston 13 is spherical, it can always come into sliding contact with the cylinder bore 12, which is formed in a cylindrical shape except for the upper end, and there is no need to process the cylinder bore 12 into a special shape. Therefore, ease of processing -11- is ensured.

Since the spherical part 17 is provided at the upper end of the cylinder bore 12, when the connecting rod-integrated piston 13, which has a spherical outer periphery, reaches the top dead center position, the first
The dead volume 5 between the piston outer periphery and the cylinder bore that occurred in the illustrated example is filled with the spherical portion 17, and the dead volume 5 is removed.

When the dead volume is eliminated, areas that are difficult for flame to penetrate are removed, resulting in better combustion, which naturally reduces knocking and reduces emissions of unburned components. When knocking becomes less likely to occur, it becomes possible to further increase the compression ratio to improve output, but by removing dead volume it becomes easier to ensure compression, and these effects work synergistically. Furthermore, since the combustion that was occurring in the dead volume portion is no longer performed, the piston ring 14 is no longer directly exposed to the combustion chamber, and the temperature of the piston ring 14 decreases.

Further, in the first and second embodiments using the collar 18, the gasket 2o is connected to the combustion chamber 20 by the collar 18.
Since it is more blocked, the sealing performance is improved accordingly. Furthermore, since the gasket 20 is no longer directly exposed to the combustion chamber 21, the gasket 20 is prevented from becoming stale and flaming fire is prevented.
In the case of the second embodiment, in which the cylinder head 10 and the cylinder block 11 are positioned accurately, variations in the combustion chamber compression ratio from engine to engine are reduced;
Performance can be improved for all engines. Furthermore, by selecting the material of the collar 18, the wall temperature can be increased.
Unburned hydrocarbons can be reduced through complete combustion.

Furthermore, in the third embodiment in which the spherical portion 17 is formed on the cylinder head 10, processing is easier than in the case where the spherical portion 17 is formed at the upper end of the cylinder block 11 or when the collar 18 is employed. In addition, it is better to provide the spherical portion 17 at the cylinder spacing 12-o than at the upper end of the cylinder block 11 because it forms a water jacket on the back of the spherical portion 17, which makes it easier to lower the wall temperature of the spherical portion 17 and also to reduce the piston ring temperature. You can donate.

As is clear from the above description, when using the cylinder head bore structure for a connecting rod-integrated piston of the present invention, knocking can be suppressed through the removal of dead volume by providing a spherical shaped portion at the upper end of the cylinder bore. Effects such as being able to reduce unburned components in exhaust gas can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of a connecting rod-integrated piston previously proposed by the applicant of this patent; FIG. 2 is a cross-sectional view of a cylinder bore structure for a connecting rod-integrated piston according to a first embodiment of the present invention; 3 is a partial cross-sectional view of a connecting rod-integrated piston having a structure different from that shown in FIG. 2, and FIG. 4 is a partial cross-sectional view of a connecting rod-integrated piston having a structure different from that shown in FIGS. 2 and 3. Figure 5 is a partial sectional view of a connecting rod-integrated piston having a structure different from that shown in Figs. 2 to 4, and Fig. 6 has a structure further different from that shown in Figs. 2 to 5. FIG. 7 is a partial cross-sectional view of a cylinder bore structure for a connecting rod-integrated screw according to a second embodiment of the present invention, and FIG. 8 is a third embodiment of the present invention. FIG. 2 is a partial cross-sectional view of a cylinder bore structure for a piston with an integrated connecting rod according to an example. 10... Cylinder head 11... Cylinder block 12... Cylinder bore 13... Connecting rod integrated screw 1 14... Piston ring 17 ..... Spherical shaped part 18 ..... Collar 20 ..... Gasket 1- 2nd 181°1 17' 219R 3a 1 13'a' 4 3- +3b 24 5 -1 / ) (3 ゝ--- 2 Figure 7 Figure 8\l

Claims (5)

[Claims] (1) In a cylinder bore in which a connecting rod-integrated piston having a spherical outer circumferential shape is slidably and reciprocally movable, the piston follows the spherical shape of the outer circumference of the piston when the upper end of the cylinder bore is at the top dead center position. A cylinder bore structure for a piston with an integrated connecting rod, characterized by a spherical shape with a tapered top. (2) The cylinder bore structure for a connecting rod integrated piston according to claim 1, wherein the cylinder bore is provided in at least one of the cylinder block and the cylinder head provided on the upper part of the cylinder block. (3) The cylinder bore structure for a connecting rod integrated piston according to claim 2, wherein the spherical portion at the upper end of the cylinder bore is formed by a collar separate from the cylinder block and cylinder head. (4) The cylinder bore structure for a connecting rod-integrated piston according to claim 3, wherein the outer periphery of the collar is fitted to at least one of a cylinder block and a cylinder head with a pilot. (5) The cylinder bore structure for a connecting rod integrated piston according to claim 2, wherein the spherical portion at the upper end of the cylinder bore is formed on the cylinder head side.