JPS591082Y2 - engine piston - Google Patents

Description

[Detailed explanation of the idea] This idea relates to engine pistons.

As shown in FIG. 1, the upper and lower side walls 2 of the ring groove 1 of the piston are hammered by the piston ring 3 and gradually wear out.

When the wear progresses and a step 5 is formed between the inner end of the worn part 4 and the side wall 2 as shown by the imaginary line, the back surface of the ring bites into the step 5, making it impossible to contract and deform the ring. Moreover, is it worn out? As the side clearance increases, the piston ring 3 moves in an abnormal posture with a large inclination.

As a result, when the moving direction of the piston changes or when the piston attempts to swing around the pin, excessive force is applied and the piston ring 3 may break, or the ring face may remain in an inclined position and cause local damage. This may cause abnormal wear of the cylinder and its gas sealing effect may be significantly reduced.

This idea solves the above-mentioned problems by ensuring that the piston ring can be reliably contracted and deformed even when the ring groove is worn out. It is characterized in that a relief groove is formed near the end with a depth at least equivalent to the allowable wear amount of the same side wall and a width at least equivalent to the back gap.

Examples of this invention will be described below based on the drawings.

FIG. 2 is a sectional view of the main part of the piston.

In the figure, 10 is a cylinder, and 11 is an aluminum alloy piston.

A ring groove 13 into which a piston ring 12 is fitted is formed in a portion of the circumferential surface of the piston 11 near the head.

This ring groove 13 is formed into a dovetail shape as a whole, consisting of vertically facing side walls 14, a bottom wall 15 at the far end of these, and relief grooves 16 formed at the corners of both side walls 14 and bottom wall 15. has been done.

A required amount of a side gap S and a back gap G are set between the piston ring 12 and the side wall 14 or the bottom wall 15, respectively.

As shown in FIG. 3, the relief groove 16 has a width B equal to the sum of the back gap G and the chamfered width C of the back of the piston ring 12, and is set slightly larger than this. The distance D is set to be slightly larger than the allowable wear amount of the side wall 14.

If the piston ring 12 is intercepted as described above, even if the ring groove 13 wears out, a step will not be formed at the rear end of the worn surface, so the piston ring 12 can be freely contracted and deformed, causing the ring 12 to break or become abnormal. It is possible to eliminate the problem of moving in the same posture.

Note that the back chamfer of the piston ring 12 may be formed into a curved surface.

As explained above, in this design, even if the side wall of the ring groove wears to near the permissible limit, a relief groove is formed near the inner end, so unlike the previous one, No step is generated at the inner end of the worn surface, and the piston ring can reliably contract and deform.

Therefore, even if the piston ring momentarily comes into sliding contact with the cylinder in an inclined position, it is possible to prevent the ring from contracting and deforming and applying unreasonable force to it, thereby preventing the piston ring from breaking. , it is possible to reliably prevent the cylinder from operating in an abnormal position and causing abnormal wear.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the main part of a piston showing a conventional example, Figs. 2 and 3 show an embodiment of this invention, Fig. 2 is a sectional view of the main part of a piston, and Fig. 3 is a main part of the piston. FIG. 10...Cylinder, 11...Piston, 12...
Piston ring, 13...Ring groove, 14...13
side wall, 15...13 bottom wall, 16... relief groove,
B... Width of 16, D... Depth of 16, G... Back gap, C... Chamfer width, K... Allowable wear amount.

Claims (1)

[Claims for Utility Model Registration] ■ A relief groove 16 is formed in each of the rear end portions of a pair of side walls 14 that intersect the ring groove 13 of the piston 11 to allow the back corners of the piston ring 12 to escape. death,
The width B of the relief groove 16 is set equal to or more than the back gap G of the piston ring 12, and the depth D of the gap groove 16 is set equal to or more than the allowable wear amount of the side walls 14. The piston of the engine. 2. In the engine piston described in claim 1 of the utility model registration claim, the width B of the relief groove 16 is set to be slightly larger than the sum of the back gap G and the chamfer width C of the back corner of the piston ring 12. thing.