JPH08121595A - Piston for reciprocating engine - Google Patents

Abstract

PURPOSE: To reduce the consumption of lubricating oil by preventing the floating of a top ring in a ring groove while an engine is driven. CONSTITUTION: Communicating holes 30, 31, 32 to communicate a top land clearance 11 and a second land clearance 12 to each other are provided, and a check valve 300 to communicate the second land clearance 12 and the top land clearance 11 to each other by opening the valve only at the time when pressure P2 of the second land clearance 12 is higher than pressure P1 of the top land clearance 11 is provided in the communicating hole 31.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art FIG. 5 is a sectional view showing the vicinity of a conventional piston for an internal combustion engine. In the figure, 01 is a cylinder liner, 03 is a piston fitted in the cylinder liner 01 so as to reciprocate, 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. Reference numeral 020 is a piston rod that connects the piston 03 and a crosshead (not shown).

08 is the top land of the piston 03, 09
Is a Senkado land, 011 is a top land gap formed between the top land 08 and the inner surface of the cylinder liner 01, 01
Reference numeral 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 equipped with the above 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 is the seal of the top ring 04. The pressure becomes P ₂ by the action.

As shown in FIG. 6, the relationship between the pressures P ₁ and P ₂ is that the first half of the compression stroke in which the piston 03 goes from the bottom dead center to the top dead center and the expansion stroke in which the piston 03 goes from the top dead center to the bottom dead center. Up to P ₁
> P ₂ , but in the latter half of the expansion stroke, P ₁ <P ₂ .

Therefore, the gas pressure behaves as the top ring 04 moves.
As shown in FIG. 7, the force exerted on (hereinafter referred to as ring behavior) is downward in the compression stroke and the first half of the expansion stroke, that is, it acts so as to bring the top ring 04 into close contact with the lower surface of the ring groove 013, and the expansion stroke. In the latter half of the above, contrary to the above, it acts upward, that is, it acts so as to try to lift the top ring 04 from the ring groove 013.

The force acting on the top ring 04 includes not only the gas pressure but also the frictional force generated between the inner surface of the cylinder liner 01 and the outer peripheral surface of the top ring 04 and the inertial force of the top ring 04 itself. As shown in FIG. 8, the top ring 04 is seated on the lower surface of the ring groove 013 for a predetermined period of time, and the upper surface of the ring groove 013 is affected by the gas pressure, as compared with the force of. Sit for a predetermined period of time.

[0009]

As shown in FIG. 9, while the top ring 04 is seated on the lower surface 013a of the ring groove 013, the sealing property on the seating surface is good, so that the leakage gas flow Is mostly from the 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 slid.
4, the gap 25 is formed, and as shown by the arrow in FIG. 10, the gas flowing through the gap 25 is added to the flow of the gas passing through the gap, so that the amount of leaked gas increases.

At this time, the lubricating oil rises from the topland gap 012 to the topland gap 011 along with the leaked gas, and further 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 which can reduce the consumption of lubricating oil by preventing the top ring from rising in the ring groove.

[0013]

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

[0014]

In the present invention, the pressure in the second land gap is
When P ₂ becomes higher than the pressure P _{1 in the} topland clearance, the check valve opens, the topland clearance and the second land clearance communicate with each other through the communication hole, and the pressures in these clearances are balanced.

As a result, lifting of the top ring in the ring groove is prevented, and good sealability is maintained between the lower surface of the top ring and the ring groove.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An 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 is a top land gap formed between the top land 8 and the inner surface 1a of the cylinder liner 1, and 12 is a second land gap formed between the second land 9 and the inner surface 1a of the cylinder liner 1. .

Top land gap 11 and second land gap
12 is a communication hole 32, 30 formed in the piston 3;
They are communicated with each other by 31. That is, the horizontal communication hole 32 opening to the topland gap 11 and the horizontal communication hole 31 opening to the second land gap 12 are connected by the vertical communication hole 30 formed from the lower surface of the piston 3, and the topland gap 11 and the second communication hole 31 are connected. Gas can flow between the land gap 12.

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

[0020] The check valve 300 is a pressure P ₂ is the top land of second land when the pressure P ₂ of the gap 12 is higher than the pressure P ₁ in the top land clearance 11 (strictly second land gap 12 is Only when the pressure P ₁ in the gap 11 becomes higher than the sum of the elastic force of the return spring 35), the gas in the second land gap 12 is made to flow to the topland gap 11.

The check valve 300 allows the gas in the second land gap 12 to flow into the topland gap 11 when P ₁ > P ₂ and shuts off the gas flow in other cases. The structure shown in FIG. 1 is not necessary. 37 is a vertical communication hole
It is a plug for closing the lower end of 30.

During operation of the internal combustion engine, however, the same cylinder pressure P _{1 as} in the combustion chamber 2 acts on the top land gap 11, and the gas pressure P ₂ in the second land gap 12 is the seal of the top ring 4. Due to the action, the pressure becomes P ₂ lower than P ₁ .

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

As a result, the gas in the second land gap 12 flows through the check valve 300, 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 hold. The condition of P ₁ > P ₂ is maintained.

Therefore, as shown in FIG. 3, the downward force is always applied to the top ring 4,
As shown in FIG. 5, the top ring 4 is always seated on the lower surface 13a of the ring groove 13 with a predetermined force.

Therefore, the top ring is in the ring groove during operation.
It does not float from the lower surface 13a of 13 and can prevent gas and lubricating oil from blowing through 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.

[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,
The check valve opens, and the topland gap and the second land gap communicate with each other through the communication holes to balance the pressures in these gaps.

Therefore, a downward force is always applied to the top ring, and the top ring does not sit on the lower surface of the ring groove and float up.

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

[Brief description of drawings]

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

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

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

FIG. 4 is a diagram showing a relationship between a seating period of a ring and a crank angle in the above 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 seating period of a conventional ring and a crank angle.

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

FIG. 10 is a partially enlarged cross-sectional view showing a lifted state of the top ring.

[Explanation 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 clearance 12 Second land clearance 13 Ring groove 30, 31, 32 Communication hole 300 Check valve

Claims (1)

[Claims] 1. A piston for a reciprocating engine, which is reciprocally fitted in a cylinder liner and comprises a plurality of piston rings fitted in a ring groove, wherein a top land of the piston and the cylinder liner are provided. The top land gap formed between the inner surface and the second land of the piston and the communication hole that communicates with the second land gap formed between the inner surface of the cylinder liner, and the pressure P _{2 of the} second land gap. For a reciprocating engine, which is provided with a check valve that opens only when the pressure in the topland gap is higher than P ₁ to allow the topland gap and the second land gap to communicate with each other through the communication hole. piston.