JP2651944B2 - Piston with asymmetric full keystone piston ring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention mainly relates to a piston ring loosely fitted to a piston of a reciprocating internal combustion engine.

[Prior Art] A piston ring for an internal combustion engine has a purpose of preventing gas leakage from a combustion chamber of a high-pressure combustion gas to a crankcase and adjusting an oil film on a cylinder wall surface. It fulfills its function.

As a conventional piston ring, a ring having a rectangular cross-sectional shape as shown in a piston ring 41 in FIG.
As these modifications, a conical ring or the like is used. However, especially in high-speed diesel engines, the rise in combustion temperature due to the recent increase in supercharging has led to an increase in piston temperature, an increase in speed, and an increase in the surface pressure of the piston ring in the radial direction. In order to cope with the problem, a full keystone type piston ring 51 (hereinafter referred to as a keystone ring) shown in FIG. As a result, it has been effective in preventing stick of the piston ring, preventing vibration of the ring, discharging combustion products, and the like.

[Problems to be solved by the invention]

However, recent high-speed diesel engines are required to have strict performance and functions with respect to pistons, piston pings, and the like due to further downsizing and higher output and regulation of emission of combustion products. In particular, prevention of ring stick due to oil deterioration and reduction of oil consumption due to high combustion pressure and high combustion gas temperature are important issues for achieving the required performance and function of the high-speed diesel engine.

The problems of the conventional keystone ring corresponding to these will be described with reference to FIGS. 2A and 3B and FIGS. 3A and 3B. FIG. 2A
Shows the configuration of the conventional keystone ring and piston,
The inclination angle of the groove and the ring when the piston 22 and the keystone ring 21 are loosely fitted shows a relationship of θ _R1 = θ _R2 <θ _P. FIG. 2B
2A, in the explosion stroke of the combustion chamber of the engine, the combustion gas is pressurized on the upper surface and the inner diameter of the keystone ring 21 in the direction indicated by the arrow in the drawing, and the keystone ring 21 is And the inner wall of the cylinder 23. At the same time, the keystone ring 21 acts on the contact point P shown in FIG. 2B as a fulcrum in the direction of arrow A, and a strong contact is generated on the contact surface of the portion F in FIG. 23 The oil attached to the wall is scraped down, which is effective in reducing oil consumption.

On the other hand, when the piston slides upward during the compression and exhaust strokes, the upper surface of the groove of the piston 22 and the keystone ring
21 The gap between the upper surface and the outer periphery, that is, the "oil inflow" shown
The passage becomes large and the amount of inflow of oil becomes excessive, so that the deterioration of the oil caused by the combustion gas heat and the frictional friction heat and the problem of sticking (also referred to as sticking) between the piston and the keystone ring due to the combustion products are likely to occur. . FIG. 3A also shows a conventional configuration of a keystone ring and a piston. In this case, the relationship between the groove of the piston 32 and the inclination angles of the upper and lower surfaces of the keystone ring 31 is θ _R1 = θ _R2 > θ _P. . Third
In FIG. B, as in FIG. 2B, the keystone ring 31 is pressurized by the combustion gas pressure in the direction indicated by the arrow in the drawing.

On the other hand, the moment due to the gas pressure in the direction of arrow H with the contact point Q shown in the figure as a fulcrum is small and opposite to the moment A in FIG. 2B, and the effect of scraping off the oil attached to the wall of the cylinder 33 is small. , Increase oil consumption.

On the other hand, as shown in the arrow of FIG.
Since the gap between the outer peripheral portion of the ring groove 32 and the upper surface of the outer peripheral portion of the keystone ring 31 is small, the inflow of oil is small, and the stick phenomenon is prevented.

As described above, the conventional keystone piston ring has advantages and disadvantages.

The present invention has been made with a view to solving the above-described problems by focusing on the problems described above, reducing the oil consumption and improving the angle of the piston groove and the inclination angles of the upper and lower sides of the keystone ring as a structure that is strong against the stick. Things.

[Means for solving the problem]

In order to achieve the above object, according to the present invention, in a piston having an asymmetric full keystone piston ring which is loosely fitted in a groove of a piston, the piston is inclined and widened to an outer diameter portion from an inner diameter portion of the piston, and the outer circumference of the piston is into the four symmetry of the piston, the top surface angle of inclination theta _R1 is larger than the predetermined groove inclination angle theta _P of the piston, and the lower surface inclination angle theta _R2 piston having a predetermined groove inclination angle theta _P with respect to a vertical line perpendicular and a asymmetrical full keystone piston ring having a predetermined groove inclination angle theta _P smaller cross-sectional shape.

(Operation)

According to the above configuration, the inflow of the scraped-up oil from the upper surface is reduced, the stick is prevented from being reduced, and the lower surface is set to θ _P > θ _R2 , so that the ring tilt angle is increased, and the oil is attached to the cylinder inner wall. This effectively acts to scrape down the oil, thereby reducing oil consumption.

〔Example〕

 Next, the present invention will be described with reference to the drawings and embodiments.

FIG. 1 is a sectional view showing an embodiment in which a keystone ring 1 of the present invention is loosely fitted to a piston 2 and an outer diameter portion is circumferentially in contact with an inner wall of a cylinder liner 3. The groove shape of the piston 2 into which the keystone ring 1 is loosely fitted is linearly inclined from the inner diameter portion to the outer diameter portion and widened as shown in the figure, and the inclination angle θ _P is perpendicular to the outer periphery of the piston. The angle with respect to (Y) is shown. Further, the groove shape of the piston 2 is formed in the same inclination angle theta _P vertically symmetrical.

On the other hand, the cross-sectional shape of the keystone ring 1 loosely fitted to the piston 2 conforms to the shape of the piston groove as shown in the figure, but the relationship between each of the upper surface inclination θ _R1 and the lower surface inclination angle θ _R2 has a slight angle difference θ _R1. > Θ _R2 , the piston 2 is loosely fitted to the piston 2 and the outer peripheral portion is in circumferential contact with the inner wall of the cylinder liner 3. The relationship between the inclination angles of the upper and lower inclined portions of the groove of the keystone ring 1 and the piston 2 is θ _R1 > θ _P > θ _R2 , and the inclination angles generally used are 7 to 8 ° and θ _P and θ
The difference between the inclination angles of _R1 and θ _R2 is very small, about 10 to 15 ′.

The configuration of the piston and the keystone ring as described above causes a strong contact with the contact surface with the inner wall of the cylinder 3, and the oil attached to the wall of the cylinder 3 is scraped down to reduce the oil consumption. In addition, the gap between the outer peripheral portion of the ring groove of the piston 2 and the upper surface of the outer peripheral portion of the keystone ring 1 is reduced, so that the amount of oil flowing in is reduced and the stick phenomenon is prevented.

〔The invention's effect〕

As described above, according to the present invention, θ _R1 > θ _P >
By adopting the cross-sectional shape of the keystone ring that becomes θ _R2 , it is possible to reduce the oil consumption and prevent the stick phenomenon.

[Brief description of the drawings]

FIG. 1 is a sectional view of the keystone ring of the present invention loosely fitted to a piston. FIGS. 2A and 2B and FIGS. 3A and 3B are cross-sectional views illustrating the function and operation of a conventional keystone ring and showing a difference from the keystone ring of the present invention. FIG. 4, FIG.
The figure is a cross-sectional view showing the configuration of a conventional piston and piston ring. 1 ... keystone ring, 2 ... piston, 3 ... cylinder

Claims (1)

(57) [Claims] In a piston provided with an asymmetric full keystone piston ring which is loosely fitted in a groove of a piston, the piston is inclined and widened from an inner diameter portion to an outer diameter portion and is perpendicular to a vertical line perpendicular to the outer periphery of the piston. Predetermined groove inclination angle θ _P
The upper surface inclination angle θ _R1
There greater than a predetermined groove inclination angle theta _P of the piston, and,
A piston provided with an asymmetric full keystone piston ring having a cross-sectional shape whose lower surface inclination angle θ _R2 is smaller than a predetermined groove inclination angle θ _{P of} the piston.