JP3349281B2 - Piston for reciprocating engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston used for a reciprocating engine such as a reciprocating internal combustion engine and a reciprocating compressor.

[0002]

2. Description of the Related Art FIG. 5 is a sectional view showing the vicinity of a conventional piston for a reciprocating internal combustion engine. In the figure, 01 is a cylinder liner, 03 is a piston fitted reciprocally in the cylinder liner 01, and 02 is a combustion chamber.

A plurality of piston rings 04, 05, 06, 07 for sealing high-pressure combustion gas generated in the combustion chamber 02 are fitted around the outer periphery of the piston 03. 020 is a piston rod connecting the piston 03 and a crosshead (not shown).

[0004] Also, 08 is the top land of piston 03, 09
Is Senkadando, 011 is a topland gap formed between the topland 08 and the inner surface of the cylinder liner 01, 01
2 is a second land gap formed between the second land 09 and the inner surface of the cylinder liner 01.

During operation of the internal combustion engine having the piston, the same cylinder pressure P _{1 as} in the combustion chamber 02 acts on the top land gap 011, and the gas pressure in the second land gap 012 changes the seal of the top ring 04. the pressure P ₂ by the action.

[0006] relationship between the pressure P ₁ and P _2, as shown in FIG. 6, the first half of the compression stroke and the top dead center toward the top dead center from the piston 03 bottom dead center of the expansion stroke towards the bottom dead center Until P ₁
> It is a P _2, in the second half of the expansion stroke, the P ₁ <P _2.

Accordingly, the force exerted by the gas pressure on the behavior of the top ring 04 (hereinafter referred to as ring behavior) is downward in the compression stroke and the first half of the expansion stroke as shown in FIG. 13 lower surface 1
3a , and acts upward in the latter half of the expansion stroke.
The acts on the gel so has a lower surface 13a of the ring groove 13.

The forces acting on the top ring 04 include, besides the gas pressure, a frictional force generated between the inner surface of the cylinder liner 01 and the outer peripheral surface of the top ring 04 and an inertia force of the top ring 04 itself. As shown in FIG. 8, the top ring 04 is seated on the lower surface 13a of the ring groove 013 for a predetermined period of time because the gas pressure has a greater effect on the sealing behavior of the top ring 04 than the force of the ring groove 013. Upper surface 13b
For a predetermined period.

[0009]

As shown in FIG. 9, during the period in which the top ring 04 is seated on the lower surface 013a of the ring groove 013, the sealing performance on the seating surface is good, so that the flow of the leak gas is reduced. Most are from the opening gap of the top ring 04.

However, as shown in FIG. 10, while the top ring 04 is seated on the upper surface 013b of the ring groove 013, the sludge 01 attached to the upper surface of the top ring 04 is not used.
4, a gap 25 is formed, and as shown by an arrow in FIG. 10, the gas flowing through the gap 25 is added to the gas flowing through the gap, so that the amount of leaked gas increases.

At this time, the lubricating oil is
It rises from the second land gap 012 to the top land gap 011 and flows out to the combustion chamber 02 where it is burned and consumed.

An object of the present invention is to provide a piston for a reciprocating engine capable of reducing the consumption of lubricating oil by preventing floating of a top ring in a ring groove.

[0013]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its gist is that it is fitted reciprocally in a cylinder liner and is fitted in a ring groove. In a piston for a reciprocating engine having a plurality of piston rings fitted therein, a top land gap formed between a top land of the piston and an inner surface of the cylinder liner, a second land of the piston, and the cylinder liner A communication hole that communicates with the second land gap formed between the top land gap and the second land gap is opened only when the pressure P ₂ of the second land gap is higher than the pressure P _{1 of the} top land gap. And a second land gap through the communication hole.

[0014]

In the present invention, the pressure in the second land gap
When P ₂ is higher than the pressure P ₁ of the top land clearance, top land clearance and second land clearance check valve is opened to balance the pressure of both of these gaps in communication via the communicating hole.

This prevents the top ring from floating in the ring groove, and maintains a good seal between the lower surface of the top ring and the ring groove.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described in detail with reference to FIGS. In FIG. 1, 1 is a cylinder liner, 3 is a piston, 2 is a combustion chamber, 4, 5, 6, and 7 are piston rings, and 20 is a piston rod.

Reference numeral 11 denotes a top land gap formed between the top land 8 and the inner surface 1a of the cylinder liner 1, and reference numeral 12 denotes a second land gap formed between the second land 9 and the inner surface 1a of the cylinder liner 1. .

The top land gap 11 and the second land gap
12 is a communication hole 32, 30, or
They are interconnected by 31. That is, the horizontal communication hole 32 opening in the top land gap 11 and the horizontal communication hole 31 opening in the second land gap 12 are connected by the vertical communication hole 30 drilled from the lower surface of the piston 3, and the top land gap 11 and the second communication hole are connected. The gas can flow between the land gap 12.

A check valve 30 having a spherical valve body 34, a valve seat member 33, a return spring 35, and a spring receiver 36 is provided in the horizontal communication hole 31.
0 is arranged.

When the pressure P ₂ in the second land gap 12 becomes higher than the pressure P ₁ in the top land gap 11 (strictly speaking, the pressure P ₂ in the second land gap 12 becomes opens only when it becomes higher than the sum of the elastic force of the spring 35 back to the pressure P ₁ in the gap 11), so that the allowed to flow the gas second land clearance 12 to top land clearance 11.

It should be noted that the non-return valve 300 may be any valve that allows the gas in the second land gap 12 to flow to the top land gap 11 when P ₂ > P ₁ and that can block the flow of gas in other cases. The structure may not be as shown in FIG. 37 is a vertical communication hole
It is a plug for closing the lower end of 30.

During operation of the internal combustion engine, the same cylinder pressure P ₁ acts on the top land gap 11 as in the combustion chamber 2, and the gas pressure P ₂ on the second land gap 12 is a lower pressure P ₂ than P ₁ by the action.

As shown in FIG. 2, P ₁ > P ₂ during the compression stroke and the first half of the expansion stroke of the piston 3, but when P ₂ > P ₁ in the latter half of the expansion stroke, the check valve is required. 300 opens.

As a result, the gas in the second land gap 12 flows through the check valve 300 and the communication holes 31, 30, 32 in this order and flows out to the top land gap 11, so that P ₂ > P ₁ does not occur. The state of P ₁ > P ₂ is maintained.

Therefore, as shown in FIG. 3, a downward force acts on the top ring 4 at all times.
As shown in FIG. 7, the top ring 4 is always seated on the lower surface 13a of the ring groove 13 with a predetermined force.

Therefore, during operation, the top ring is
The gas and the lubricating oil can be prevented from being blown from the back of the top ring 4 through the gap between the upper surface of the top ring 4 and the lower surface of the ring groove 13 without floating from the lower surface 13a of the top ring 4.

[0027]

According to the present invention, when the pressure P _{2 in} the second land gap becomes higher than the pressure P _{1 in the} top land gap,
When the check valve opens, the top land gap and the second land gap communicate with each other through the communication hole, and the pressures in these gaps are balanced.

Therefore, a downward force acts on the top ring at all times, and the top ring does not sit on the lower surface of the ring groove and float.

As a result, it is possible to prevent the lubricating oil from rising to the top land gap through the gap between the upper surface of the top ring and the lower surface of the ring groove together with the gas, so that the consumption of the lubricating oil can be reduced. it can.

[Brief description of the drawings]

FIG. 1 is a sectional view of a piston for an internal combustion engine according to an embodiment of the present invention, showing the vicinity thereof.

FIG. 2 is a diagram showing a relationship between a gas pressure and a crank angle in the embodiment.

FIG. 3 is a diagram showing a relationship between a force acting on a ring behavior and a crank angle in the embodiment.

FIG. 4 is a diagram showing a relationship between a ring sitting period and a crank angle in the embodiment.

FIG. 5 is a cross-sectional view showing a conventional piston for an internal combustion engine in the vicinity thereof.

FIG. 6 is a diagram showing a conventional relationship between gas pressure and crank angle.

FIG. 7 is a diagram showing a relationship between a force exerted on a conventional ring behavior and a crank angle.

FIG. 8 is a diagram showing a relationship between a sitting period of a conventional ring and a crank angle.

FIG. 9 is a partially enlarged sectional view showing a seating state of a top ring.

FIG. 10 is a partially enlarged sectional view showing a floating state of a top ring.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder liner 2 Combustion chamber 3 Piston 4 Top ring 5, 6, 7 Piston ring 8 Top land 9 Second land 11 Top land gap 12 Second land gap 13 Ring groove 30, 31, 32 Communication hole 300 Check valve

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16J 9/00 F02F 3/00

Claims (1)

(57) [Claims] 1. A reciprocating engine piston having a plurality of piston rings fitted reciprocally in a cylinder liner and fitted in a ring groove, wherein a top land of the piston and a cylinder liner are provided. A communication hole that communicates the top land gap formed between the inner surface and the second land of the piston and the second land gap formed between the inner surface of the cylinder liner and the pressure P _{2 of the} second land gap. and opened only when higher than the pressure P ₁ of the top land crevice reciprocating engine, characterized in that the said top land clearance and second land clearance is provided a check valve occupies passed, communicating through the communicating hole piston.