JPH03213641A - Cylinder sealing device of 2-cycle engine - Google Patents

Abstract

PURPOSE:To obtain a high sealing property by providing a permanent magnet at the outer circumference of a piston to make the permanent magnet absorb a seal ring which consists of a magnetic fluid so as to seal a combustion chamber, and adding further the magnetic force of a fixed electromagnet near the top dead center to hold the magnetic fluid. CONSTITUTION:A cylinder liner 11 is inserted to the inner circumferential surface of a cylinder 1, and a piston 2 made of a nonmagnetic material is inserted slidable at the inner side of the cylinder liner 11. While the end surface of the head of the piston 2 is covered with an adiabatic layer 21 of a ceramics or the like, a ring-form permanent magnet 3 is provided at the outer circumferential surface of the piston 2, and a ring-form separator 31 made of a nonmagnetic substance is provided between the both magnetic poles of the permanent magnet 3. A circulating pipe line 13 for the cooling fluid is provided at the upper circumference of the cylinder liner 11, a ring-form core 43 made of a magnetic substance is inserted to the pipe line 13, and an exciting coil 44 is wound on the core 43. And a seal ring 5 which consists of a magnetic fluid is placed between the magnetic poles 32 and 33 and the cylinder liner 11, which is absorbed magnetically to seal a combustion chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a cylinder seal device for a two-stroke engine that seals the inner circumferential surface of a cylinder and the outer circumferential surface of a piston using a magnetic fluid.

(Prior art) The cylinder seal in a conventional two-stroke engine is
A plurality of piston rings are interposed between the inner peripheral surface of the cylinder and the outer peripheral surface of the piston to isolate the inside and outside of the combustion chamber.

The piston ring is an annular ring with a portion of its circumference cut away, and the diameter of the outer circumferential portion of the circular tube is larger than the inner diameter of the cylinder by a predetermined amount.

The inner diameter portion of the piston ring is placed into a groove carved on the outer peripheral surface of the piston, and the piston ring is inserted into the cylinder. Then, the piston ring expands and presses against the inner peripheral surface of the cylinder.

Therefore, the piston ring isolates the inside of the combustion chamber from the outside of the crankcase.

(Problems to be Solved by the Invention) Such a conventional piston ring that seals the inner circumferential surface of the cylinder and the outer circumferential surface of the piston is designed to prevent hydrocarbons and other substances in the combustion chamber from entering the notch, or abutment, of the piston ring. Unburned gas becomes blow-by gas and leaks outside, causing air pollution.

Furthermore, there is a problem in that the lubricating oil in the crankcase enters the combustion chamber through the joint, increasing the amount of lubricating oil consumed, and as the lubricating oil burns, white smoke is emitted along with the exhaust gas.

Furthermore, when the piston ring passes through the intake port part drilled in the cylinder liner, there is a risk that the piston ring may get caught in the intake port opening and break, so the piston ring is positioned on the piston side. Therefore, there is a problem that the piston rings are likely to seize.

The present invention has been made in view of the above-mentioned points, and provides a perfect seal between the inner circumferential surface of the cylinder and the outer circumferential surface of the piston, thereby preventing the leakage of blow-by gas from the combustion chamber and the intrusion of lubricating oil into the combustion chamber. It is an object of the present invention to provide a cylinder seal device for a two-stroke engine that can completely prevent the above problems.

(Means for Solving the Problems) According to the present invention, in a cylinder seal device for a two-stroke engine having an intake port in a cylinder liner that opens to a combustion chamber at bottom dead center, a permanent magnet having an annular movable magnetic pole; an electromagnet having a fixed magnetic pole facing the movable magnetic pole at a position near the top dead center of the piston; and when the movable magnetic pole and the fixed magnetic pole face each other, the electromagnet is energized. an energization control means that forms a closed circuit of magnetic flux between the magnetic poles; and a energization control means that is continuously interposed over the entire circumference between the movable magnetic pole and the inner circumferential surface of the cylinder liner, and that controls the closed circuit of the magnetic flux when the electromagnet is energized. a sealing ring made of magnetic fluid that forms a part of the movable magnetic pole and forms a path for magnetic flux passing through the movable magnetic pole when not energized, a magnetic fluid retaining groove that communicates with the intake port and is provided around the inner wall of the cylinder liner, and the movable magnetic pole. It is possible to provide a cylinder seal device for a two-stroke engine, characterized in that it has a magnetic fluid recovery groove that is in contact with the outer periphery of the piston and is provided around the outer periphery of the piston.

(Function) In the cylinder seal device for a two-stroke engine of the present invention, a permanent magnet is provided around the outer periphery of the piston, and a sealing ring made of magnetic fluid is attracted to the permanent magnet to seal the combustion chamber. In addition, particularly when the pressure in the combustion chamber is high near top dead center, the magnetic force of both the permanent magnet and the fixed electromagnet strongly holds the magnetic fluid and seals the combustion chamber.

In addition, when the sealing ring passes through the intake port opening from top dead center to bottom dead center, the magnetic fluid that is scraped off by the intake port is held in the retaining groove and passes from bottom dead center to top dead center. When doing so, the magnetic fluid held in the holding groove is recovered to the piston side in the recovery groove.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of the engine according to this embodiment.

1 is a cylinder, and a cylinder liner 11 is fitted into the inner peripheral surface of the cylinder 1. The cylinder liner 11
is made of a non-magnetic ceramic such as silicon nitride, and the inner peripheral surface is plated with chromium (Cr).

Therefore, the inner circumferential surface of the cylinder liner 11 has excellent wear resistance and a small coefficient of friction.

Incidentally, the cylinder liner 111 may be made of a metal material as long as it is a non-magnetic material and satisfies conditions such as predetermined strength.

The outer peripheral part of the cylinder liner 11 is a cylinder block 12.
covered with.

Note that the upper outer periphery of the cylinder liner 11 and the cylinder block 12 are not in contact with each other, and a pipe line 13 is provided on the outer periphery of the cylinder liner 11.

Engine cooling fluid, such as water or oil, circulates through the pipe 13.

The cylinder liner 11 also has an intake port 14 that opens into the cylinder 1 at the bottom dead center position of the piston 2.
is provided. The intake port 14 is constantly supplied with compressed air from a compressor (not shown).

A piston 2 is made of a non-magnetic material such as an aluminum alloy, and is slidably held within the cylinder 1. The end face of the head portion of the piston 2 is covered with a heat insulating layer 21 made of ceramic or the like having excellent heat resistance to prevent heat generated within the combustion chamber from being transmitted to the piston 2.

An annular permanent magnet 3 having a magnetic pole facing the cylinder liner 11 is disposed on the outer peripheral surface of the piston 2 at a predetermined distance from the heat insulating layer 21 . An annular separator 31 made of a non-magnetic material is arranged between both magnetic poles of the permanent magnet 3.

4 is a combustion chamber formed by the cylinder sinker 11 and the heat insulating layer 21, and the combustion chamber 4 is provided with two exhaust valves 41 and 42.

However, the number of exhaust valves provided is not limited to two.

Inside the pipe line 13, there is an annular core 43 made of a magnetic material.
It is fitted onto the outer peripheral surface of the cylinder liner 11. Further, an excitation coil 44 for exciting the core 43 is wound around the core 43.

Note that when the fluid circulating in the pipe line 13 is water, the excitation coil 44 is sufficiently insulated from the water.

Reference numeral 6 denotes a rotary shaft that is rotationally driven by the piston 2, and a rotation sensor 61 that detects the rotational speed of the rotary shaft 6 is installed near the outer circumference of the rotary shaft 6, and a rotation sensor 61 that detects the rotational speed of the rotary shaft 6. A position sensor 62 for detecting the operating position of the piston 2 is provided.

The rotation sensor 61 and the position sensor 62 are connected to the controller 7.
The controller 7 is connected to the controller 7, and a detection signal is manually input to the controller 7. Further, the excitation coil 44 is connected to the controller 7 and receives power from the controller 7.

The controller 7 includes an input/output interface that controls the input/output of signals between the rotation sensor 61, the position sensor 62, and the excitation coil 44, as well as a ROM that stores programs and the like in advance, and a program stored in the ROM. It is comprised of a CPU that performs calculations, a RAM that temporarily stores calculation results and various data, a control memory that controls the flow of signals inside the controller 7, and the like.

Details of the magnetic pole portion of the permanent magnet will be explained using FIG. 2.

FIG. 2 is an enlarged view of the permanent magnet 3.

In addition, this figure shows the case where the piston 2 is at the top dead center position,
Further, the same numbers as in FIG. 1 above indicate the same members.

Both 32 and 33 are magnetic poles of the permanent magnet 3, and in this embodiment, the magnetic pole 32 is excited to the north pole, and the magnetic pole 33 is excited to the south pole.

Moreover, both the magnetic pole 32 and the magnetic pole 33 are connected to the cylinder liner 1.
The magnetic pole 32 facing the inner peripheral surface of the combustion chamber 1 is longer than the magnetic pole 33 in the sliding direction of the piston 2, that is, in the vertical direction in this figure. There is.

A collection groove 34 is provided around the lower part of the magnetic pole 33 in this figure.

Both 45 and 46 are fixed magnetic poles of the core 43, and when power is supplied from the controller 7 to the excitation coil 44, the fixed magnetic pole 45 is excited to the S pole and the fixed magnetic pole 46 is excited to the N pole.

Therefore, the magnetic poles 32 and 8i33 of the permanent magnet 3 and the fixed magnetic poles 45 and 46 form a closed magnetic flux circuit as shown in the figure.

Further, the length of the fixed magnetic pole 46 in the vertical direction is longer than the length of the fixed magnetic pole 45 in the vertical direction.

With the above configuration, the magnetic pole 32, the fixed magnetic pole 45, and the magnetic pole 8
The opposing state of i33 and fixed magnetic pole 46 continues for a period of top dead center and a predetermined crank angle, for example, ±40° around top dead center.

A sealing ring 5 is made of magnetic fluid and isolates the combustion chamber 4 from the outside.

The magnetic fluid constituting the ring seal 5 is made by modifying the surface of fine ferrite particles with a particle size of several hundred angstroms with an organic fatty acid so that they do not separate in a dispersion medium such as engine oil. It is a fluid. Since the ferrite fine particles are stably dispersed in the dispersion medium, the fluid itself appears to have magnetic properties.

Therefore, the sealing ring 5 is interposed between the magnetic poles 32 and 33 and the cylinder liner 11, and serves as a path for magnetic flux acting between the magnetic poles 32 and 33 and the fixed magnetic poles 45 and 46.

Next, details of the opening of the intake port 14 will be explained.

FIG. 3 is a diagram showing the sealing ring 5 passing through the intake port opening.

Reference numeral 15 indicates the inner peripheral surface of the cylinder liner 11, and is a retaining groove provided around the inner circumferential surface of the cylinder liner 11 in communication with the opening of the intake port 14.

Next, the operation of this embodiment with the above configuration will be explained.

When the piston 2 is not within a predetermined crank angle centered on the top dead center, that is, when the magnet 8i32 and the magnetic pole 33 are not opposed to the fixed magnetic pole 45 and the fixed magnet [46],
The sealing ring 5 connects the magnetic pole 32 and the magnetic pole 33, and connects the magnetic pole 3
2 and the magnetic pole 33.

However, since a separator 31 made of a non-magnetic material is disposed between the magnetic poles 32 and 33, the sealing ring 5 is attached to the cylinder liner in the gap between the separator 31 and the cylinder liner 11. 11 and isolates the combustion chamber 4 from the outside, the crankcase.

By the way, when the pressure inside the combustion chamber 4 is high,
Unburned gas may leak from the upper sealing ring 5, but
The unburned gas is blocked by the lower sealing ring 5, returns once to the intake port 14, is sucked into the combustion chamber 14 again, and is combusted.

As the piston 2 slides, the sealing ring 5 also slides, but when the controller 7 detects that the piston 2 has reached a position near top dead center based on the detection signal from the position sensor 62, the excitation coil 44 is activated. Supply electricity.

Then, a closed circuit of magnetic flux is generated along the magnetic flux lines shown in FIG. 2, and the sealing ring 5 is divided into upper and lower halves. At this time, the ring seal 5
Since the holding force acting on the ring is caused by the magnetic force from the permanent magnet 3 and the excitation coil 44, the sealing ring 5 is strongly held.

When an explosion occurs inside the combustion chamber 4, the combustion chamber 4
The internal pressure of is high. However, since the sealing ring 5 is strongly held, the combustion chamber 4 can be completely sealed.

Then, the excitation coil 44 continues to be energized until the piston 2 moves a predetermined amount from the top dead center, that is, 40 degrees in crank angle as described above.

Furthermore, as the piston 2 descends, the lubricating oil adhering to the inner circumferential surface of the cylinder liner 11 is scraped off toward the crankcase by the seal ring 5 and does not enter the combustion chamber 4 .

When the piston 2 descends and passes through the opening of the intake port 14, the magnetic fluid forming the sealing ring 5 is scraped off at the edge of the opening of the intake port 14.

The scraped magnetic fluid is retained in the retaining groove 15, and when the piston 2 moves up through the bottom dead center and the sealing ring 5 passes through the opening of the intake port 14 again, the magnetic fluid retained in the retaining groove 15 is retained in the retaining groove 15. The fluid is collected into the collection groove 34.

Therefore, the magnetic fluid constituting the seal 115 does not decrease, and the sealing function of the seal ring 5 is maintained.

By the way, the reason why the head end face of the screw 6220 is covered with the heat insulating layer 21 is because the permanent magnet 3 is heated through the piston 2 due to heat transfer from the combustion chamber 4, and the permanent magnet 3 is heated beyond the Curie point. This is to prevent demagnetization or demagnetization.

Further, since the core 43 is disposed within the pipe line 13, it is cooled by the cooling fluid circulating in the pipe line 13, so that the magnetism is not impaired.

Although the embodiments of the present invention have been described in detail above, various different embodiments can be easily constructed without departing from the spirit of the present invention. It is not limited to a particular embodiment.

(Effects of the Invention) As explained above, a permanent magnet is provided around the outer circumference of the piston, and a sealing ring made of magnetic fluid is attracted to the permanent magnet,
The combustion chamber is sealed, and especially when the pressure in the combustion chamber is high near top dead center, the magnetic force of both the permanent magnet and the fixed electromagnet strongly holds the magnetic fluid and seals the combustion chamber, so that the inner peripheral surface of the cylinder and It is possible to completely seal with the outer peripheral surface of the piston and completely prevent blow-by gas from leaking from the combustion chamber and lubricating oil from entering the combustion chamber.

In addition, when the sealing ring passes through the intake port opening from top dead center to bottom dead center, the magnetic fluid that is scraped off by the intake port is held in the retaining groove and passes from bottom dead center to top dead center. When doing so, the magnetic fluid held in the retaining groove is recovered to the piston side in the recovery groove, so the magnetic fluid constituting the sealing ring does not decrease and the sealing function of the sealing ring is maintained.

Furthermore, since there is no piston ring that presses against the inner wall of the cylinder like in conventional engines, it is possible to provide a cylinder seal device for a two-cycle engine that reduces engine friction loss.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the engine according to this embodiment, FIG. 2 is an enlarged view of the permanent magnet 3, and FIG. 3 is a diagram showing the sealing ring 5 passing through the intake port opening. DESCRIPTION OF SYMBOLS 1... Cylinder, 2... Piston, 3... Permanent magnet, 4... Combustion chamber, 5... Ring seal, 6... Rotating shaft,
7... Controller, 11... Cylinder liner, 1
4... Intake port, 15... Holding groove, 31... Separator, 34... Recovery groove, 43... Core, 44...
...excitation coil.

Claims (5)

[Claims] (1) In a cylinder sealing device for a two-stroke engine having an intake port in the cylinder liner that opens to the combustion chamber at bottom dead center, a permanent magnet having an annular movable magnetic pole provided around the outer circumferential surface of the piston, and an electromagnet having a fixed magnetic pole facing the movable magnetic pole at a position near top dead center; and energization control for energizing the electromagnet when the movable magnetic pole and the fixed magnetic pole face each other to form a closed circuit of magnetic flux between the two magnetic poles. means, which are continuously interposed along the entire circumference between the movable magnetic pole and the inner circumferential surface of the cylinder liner, form a part of the closed circuit of the magnetic path when the electromagnet is energized, and pass through the movable magnetic pole when the electromagnet is not energized. a sealing ring made of magnetic fluid that forms a path for magnetic flux;
A cylinder seal device for a two-cycle engine, characterized in that it has a magnetic fluid holding groove that communicates with the intake port and is provided around the inner wall of the cylinder liner, and a magnetic fluid collection groove that is in contact with the movable magnetic pole and is provided around the outer circumference of the piston. . (2) The cylinder seal device for a two-stroke engine according to claim (1), wherein the piston is made of a non-magnetic material. (3) Claim (1) characterized in that the head end surface of the piston facing the combustion chamber is covered with a heat insulating layer.
The cylinder seal device for the two-stroke engine described above. (4) The cylinder seal device for a two-stroke engine according to claim (1), wherein the cylinder liner is made of a non-magnetic material. (5) The cylinder seal device for a two-cycle engine according to claim (1), wherein the inner circumferential surface of the cylinder liner is coated with chromium (Cr) plating.