JP2006132331A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine for performing miller cycle not applying load on an intake valve like a case of early close type and making intake air intruding in a combustion chamber not blow back to an intake system. <P>SOLUTION: A piston 2 is separated to a first piston (upper piston 3) in a side close to an intake valve and a second piston (lower piston 4) in a side close to a crank or the first piston 3 and the second piston 4 move in a cylinder 1 as one unit. The first piston 3 and the second piston 4 separates in an intake stroke, the separated first piston 3 and the second piston 4 get close in a compression stroke, the first piston 3 and the second piston 4 move in the cylinder 1 as one unit in an expansion stroke and an exhaust stroke. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine that performs a mirror cycle.

  An internal combustion engine that performs a mirror cycle has been attracting attention in recent years because it can prevent the occurrence of knocking by lowering the compression ratio and can improve thermal efficiency by increasing the expansion ratio.

  In an internal combustion engine that performs a mirror cycle, a type in which the intake valve is closed at a stage before the piston reaches bottom dead center in the intake stroke (so-called “early closing”: see, for example, Patent Document 1), There is a type in which the intake valve is closed at a stage after the piston reaches bottom dead center (so-called “slow closing”: see, for example, Patent Document 2).

  Here, as will be described later, in the case of the early closing type, the shape of the cam for adjusting the intake valve opening / closing timing becomes a so-called “pointed” shape. Wear of the valve member becomes a problem. For this reason, when applying a mirror cycle to an internal combustion engine used in a cogeneration system, a slow closing type is often used.

With reference to FIG. 13 and FIG. 14, the delayed closed type mirror cycle will be described in comparison with the Otto cycle.
Here, the Otto cycle consists of four steps of “intake (13-1)”, “compression (13-2)”, “combustion / expansion (13-3)”, and “exhaust (13-4)” in FIG. Show.
On the other hand, the slow closing of the mirror cycle is shown in FIG. 14 with “intake (14-1a, 14-1b)”, “compression (14-2)”, “combustion / expansion (14-3)”, “exhaust (14-4)”. ) ".
13 and 14, reference numeral 1 is a cylinder, reference numeral 2 is a piston, reference numeral 11 is an intake port, reference numeral 12 is an exhaust port, reference numeral 13 is an intake valve, reference numeral 14 is an exhaust valve, and reference numeral 9 is a combustion chamber. , Respectively.

  In the case of the mirror cycle, there are problems as described in the following items (1) and (2).

(1) In the case of early closing Since the intake valve is closed early, the intake time is shortened and it is difficult to perform sufficient intake. Also, since the intake stroke time is shortened (compared to Otto cycle and late closing), it is necessary to increase the moving speed (opening / closing speed) of the intake valve and open / close the intake valve rapidly. Sex occurs. On the other hand, if the intake valve is suddenly opened and closed, a load is applied to the valve and the valve seat.
Furthermore, since the intake valve is closed early, the shape of the cam that drives the valve becomes a so-called “pointed” shape, and wear of the valve and a valve member that opens and closes the valve in contact with the cam becomes a problem.
In addition, in order to prevent the valve and the upper surface of the piston from interfering with each other in the vicinity of the top dead center, it is necessary to provide a recess for the valve relief in the piston, so that the non-expandable (bottom dead center volume / top dead center volume) cannot be increased. This offsets the advantages of the mirror cycle.

(2) In the case of delayed closing (showing one cycle in FIG. 14) The timing of closing the intake valve 13 is delayed compared to the Otto cycle (showing all cycles in FIG. 13) ((14-1b) to FIG. 14) Therefore, air flows backward from the combustion chamber 9 to the intake system (intake port) 11 (blowback). Here, the backflowing air receives heat from the combustion chamber 9 and the temperature of the blowback reaches hundreds of tens of degrees Celsius. Therefore, the amount of heat held by the air flowing back from the combustion chamber 9 to the intake system is combusted from the intake system. The air entering the chamber 9 is heated and thermally expanded.
As a result, effective compression starts after the intake valve is closed late to achieve low compression, which is an advantage of the Miller cycle, and even when the engine itself is intended to reduce the horsepower consumption, Therefore, it is difficult to avoid knocking.
In other words, various techniques are applied to the intake system in order to prevent thermal expansion of the intake air, but the amount of heat held by the air flowing back from the combustion chamber 9 to the intake system is input to the intake air. Even if various technologies for preventing thermal expansion exist, it is impossible to prevent thermal expansion of intake air.

Such a problem has not been solved by both the conventional “early closing” type mirror cycle engine and the “late closing” type mirror cycle engine.
JP-A-8-177536 JP-A-8-291715

  The present invention has been proposed in view of the above-described problems of the prior art, and is an internal combustion engine that performs a mirror cycle, which does not impose a burden on the intake valve as in the case of the early closing type, and is a late closing type It is an object of the present invention to provide an internal combustion engine in which the intake air that has entered the combustion chamber is not blown back into the intake system as in the case of.

  The internal combustion engine of the present invention is a four-cycle internal combustion engine that performs a mirror cycle, in which the piston (2) has a first piston (upper piston 3) closer to the intake valve and a second piston (closer to the crank). The first piston (3) is separated from the lower piston (4), or the first piston (3) and the second piston (4) are integrally moved in the cylinder (1). (3) and the second piston (4) are separated in the intake stroke, the separated first piston (3) and the second piston (4) are close in the compression stroke, and in the expansion stroke and the exhaust stroke. The first piston (3) and the second piston (4) are configured to move integrally within the cylinder (1) (Claim 1).

  In the present invention, when the first piston (3) and the second piston (4) are separated or close to each other, the rods (33R, 33L) for guiding the first piston (3) are the second piston. The hydraulic damper mechanism (DL, DR) is connected to the hydraulic damper mechanism (DL, DR), and the hydraulic damper mechanism (DL, DR) is a blocking member (partition: 34L, 34R) provided to the rod (33R, 33L). Is separated into a first chamber (upper chamber 41Lu, 41Ru) and a second chamber (lower chamber 41Lb, 41Rb), and the first chamber and the second chamber are disposed in the second piston (4). Are formed in the flow path (pressure oil flow paths 44 to 46, 47L, 47R) through which the connecting fluid (pressure oil) is stored. The first chamber (upper chamber 41Lu, 41Ru) and the second chamber (lower 41Lb, 41Rb) is not communicated with the first chamber (upper chamber 41Lu, 41Lb, 41Rb) if the connecting rod (5) is inclined (more than a predetermined angle: case-by-case) with respect to the piston movement direction (vertical direction). 41Ru) and the second chamber (lower chambers 41Lb, 41Rb) are preferably configured to communicate with each other (Claim 2).

  And the flow path (pressure oil flow paths 61L, 61R) through which the pressure liquid (pressure oil) flows also to the peripheral edge of the piston side end (small end 6) of the connecting rod (5) connected to the piston. ), And the flow path (61L, 61R) formed at the peripheral edge of the piston side end (small end 6) of the connecting rod (5) has the connecting rod (5) moving in the piston moving direction (vertical). Direction), it does not communicate with the flow path (pressure oil flow paths 47L, 47R, 45) formed in the second piston (lower piston 4), but the connecting rod (5) moves the piston. The flow path (pressure oil flow paths 44 to 46, which are formed in the second piston (lower piston 4) if inclined at a predetermined angle or more (case-by-case) with respect to the direction (vertical direction). 47L, 47R), the first chamber (upper chamber 41Lu, 41Ru) and the second chamber (lower chamber 41Lb) 41Rb) and preferably configured as communicating (claim 3).

The present invention can be applied to an early closing type mirror cycle.
That is, it is possible to apply the piston (2; 3, 4) described above to an internal combustion engine of a type in which the intake valve (13) closes earlier than a normal Otto cycle.
However, since the intake valve (13) is open for a short time, the air supply amount may be reduced. Therefore, it is necessary to perform new inhalation using a supercharging mechanism or the like.

  According to the present invention having the above-described configuration, the first piston (upper piston 3) and the second piston (lower piston 4) are separated in the intake stroke, and the second piston (lower piston 4) is separated. Reaches the position closest to the crank (8) in the cylinder (1), the distance between the two (the first piston 3 and the second piston 4) becomes the maximum, and the stage before reaching the bottom dead center Even then, the upper piston (3) will not descend. As a result, even if the intake valve (13) is not "rapidly closed", the compression stroke time is shortened. That is, the compression ratio is reduced.

  In the next compression stroke, the separated first piston (3) and second piston (4) are close to each other, and at the end of the compression stroke, the first piston (3) and the second piston (4) are integrated. To do. Since the expansion stroke and the exhaust stroke are performed in a state where the first piston (3) and the second piston (4) are integrated, the first piston (3) moves in the cylinder (1). The distance becomes longer than the distance between the first piston (3) and the second piston (4) than in the intake stroke and the compression stroke. In other words, the volume of the gas expanded in the expansion stroke is increased by that amount, and the expansion ratio is increased.

  That is, according to the present invention, it is possible to execute the mirror cycle without changing the closing timing of the intake valve (13), thereby reducing the compression ratio and increasing the expansion ratio.

Here, the difference between the prior art and the present invention is that the mirror cycle according to the prior art is executed by adjusting the closing timing of the intake valve, which is the so-called “reduced low compression” or “apparent low compression”. On the other hand, in the mirror cycle performed according to the present invention, “lower compression” in the original sense is realized by piston displacement control.
That is, according to the present invention, it is possible to further reduce the compression due to the mechanical feature.

  Further, the speed of the lower piston (4) is not changed, but the speed of the upper piston (3) is decreased. Since the intake speed becomes slow, the intake resistance decreases. That is, the pumping loss can be further reduced.

  Since it is not necessary to open and close the intake valve (13) suddenly, when the intake valve (13) protrudes toward the combustion chamber (9) during intake, the piston (3) and the intake valve (13) interfere with each other. There is no fear of it.

  Since there is no need to change the opening / closing timing of the intake valve (13) as in the case of a normal Otto cycle, sufficient intake can be achieved as compared with a conventional mirror cycle of the early closing type.

Since there is no need to shorten the time during which the intake valve (13) is opened, there is no need to increase the speed in the opening / closing operation of the intake valve (13) (the opening / closing operation is abruptly performed). There is no burden on the valve seat.
In addition, since the cam does not need to have a so-called “pointed” shape, wear and breakage of the cam and the valve member that contacts the cam can be prevented.

  The intake air temperature does not rise because the blow-back phenomenon like the slow closing of the prior art does not occur. Therefore, the knocking avoidance ability is improved.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
1, the internal combustion engine of the illustrated embodiment includes a cylinder 1, a piston 2 that slides up and down in the cylinder 1, a cylinder head 10 disposed at the upper end of the cylinder 1, a crank 8, It has a connecting rod 5 for connecting the piston 2 (second piston 4 described later) and the crank.

The cylinder head 10 is formed with an intake port 11 and an exhaust port 12 having an opening on the upper end side of the cylinder 1. An intake valve 13 is disposed on the intake port 11, and an exhaust valve 14 is disposed on the exhaust port 12. Yes.
A throttle valve 16 is provided on the upstream side of the intake port 11. A spark plug 15 is disposed in the center of the lower end of the cylinder head 10.

  The piston 2 includes a first piston (upper piston, hereinafter referred to as the upper piston) 3 on the cylinder head 10 side, that is, a side closer to the supply / exhaust valve, and a second piston on the side closer to the crank 8. 1 (lower piston, hereinafter, the second piston is referred to as the lower piston) 4. A variable capacity combustion chamber 9 is formed by the top of the upper piston 3 and the lower surface of the cylinder head.

As shown in detail in FIG. 2, the upper piston 3 includes a piston body 31 and a pair of guide rods 33L and 33R extending vertically downward from the lower surface 3B of the piston body.
The piston main body 31 is formed with a piston ring groove (not shown in the figure), and the piston ring 32 is fitted in the groove.

At the tip of the pair of guide rods 33L, 33R is a disc-like member (a partition plate that separates the hydraulic chambers 41L, 41R formed in the lower piston 4 constituting a damper mechanism, which will be described later, up and down, hereinafter a disc-like member. 34L and 34R are formed.
In other words, when the hydraulic chambers 41L and 41R are regarded as cylinders, the partition plates 34L and 34R are pistons, and the pistons 34L and 34R are configured to slide in the cylinders 41L and 41R.

  On the other hand, as shown in detail in FIG. 3, the lower piston 4 is formed by a pair of cylindrical chambers hydraulic chambers 41L and 41R parallel to the central axis at positions symmetrical to the central axis (not shown) of the piston 4. Has been.

  Near the center of the lower piston 4, a small end accommodating hole 43 is formed for rotatably accommodating a side end of a small end (upper end) 6 of a connecting rod 5 described later.

The hydraulic chambers 41L and 41R communicate with the piston upper surface 4U through guide holes 42L and 42R, and are formed so that the guide rods 33L and 33R of the upper piston are slidably inserted into the guide holes 42L and 42R. Has been.
The hydraulic chambers (cylinders) 41L and 41R accommodate guide rods 33L and 33R of the upper piston and partition plates (pistons) 34L and 34R at the tip of the guide rod (the guide rod 33L of the upper piston is indicated by a two-dot chain line). , 33R and the partition rods 34L, 34R at the tip of the guide rod), the hydraulic chambers (cylinders) 41L, 41R are moved into the upper and lower chambers 41Lu, 41Lb; 41Ru by the partition plates (pistons) 34L, 34R. , 41Rb.

  A hydraulic flow path 44 is formed above the hydraulic chambers 41L and 41R to connect both oil chambers, and a hydraulic flow path 45 is formed below the hydraulic chambers 41L and 41R to communicate both oil chambers. Yes.

  A flow path 46 is formed in the center of the hydraulic pressure flow path 44 in a downward direction, and the flow path 46 is configured to communicate with the small end portion receiving hole 43. In addition, flow paths 47L and 47R rise vertically upward from the vicinity of the left and right hydraulic chambers 41L and 41R of the hydraulic flow path 45, and the flow paths 47L and 47R are formed from the center of the small end accommodating hole 43, respectively. It is formed so as to bend at a right angle at a slightly upper portion and communicate with the small end accommodating hole 43.

  The connecting rod 5 has a connecting portion 50, the small end portion (upper end portion) 6, and a large end portion (lower end portion) 7. As shown in the partial detail view of FIG. Pressure oil passages 61L and 61R are also formed at the peripheral edge of each. The flow paths 61L and 61R are separated by the extension part 62 of the connecting part 50.

  In the illustrated embodiment, upper rod guide rods 33L and 33R, partition plates 34L and 34R; hydraulic chambers 41L and 41R formed in the lower piston, hydraulic flow paths 44 to 46, 47L and 47R; Buffer springs stored in the upper chambers (upper chambers) 41Lu and 41Ru of the flow paths 61L and 61R formed in the end 6 and the partition plates 34L and 34R in the hydraulic chambers 41L and 41R of the lower piston 4 shown in the figure. S constitutes hydraulic dampers DL and DR.

Pressure oil passages 61L and 61R formed at the peripheral edge of the small end 6 of the connecting rod 5 are connected to the lower chambers 41Lb and 41Rb of the left and right dampers DL and DR via the passage 47L or 47R and the passage 45, respectively. Communicate.
In the state shown in FIG. 1 (same as FIG. 5), that is, the connecting rod 5 extends in parallel with the vertical axis, the pressure oil passages 61L and 61R are connected to the upper chambers 41Lu and 41Ru of the dampers DL and DR, respectively. Are not communicating.

  This is because the flow paths 44 and 46 communicating with the upper chambers 41Lu and 41Ru of the dampers DL and DR are blocked by the extension part 62 of the connecting part 50. Therefore, in the state shown in FIG. 1, no pressure oil circuit that connects the lower chambers 41Lb and 41Rb of the left and right dampers DL and DR and the upper chambers 41Lu and 41Ru is formed, and the lower chambers 41Lb of the dampers DL and DR are not formed. , 41Rb and the upper chamber 41Lu, 41Ru, the oil does not move.

  In contrast, as shown in FIG. 6 (intake process), FIG. 8 (compression process), FIG. 10 (expansion process), and FIG. 12 (exhaust process), the connecting rod 5 is at a certain angle with respect to the vertical axis. When tilted, the extension portion 62 of the connecting portion 50 is displaced to the left or right from the position shown in FIG. 1 (same as FIG. 5), so that the flow path 44 communicates with one of the flow paths 61L and 61R. As a result, the upper chambers 41Lu, 41Ru and the lower chambers 41Lb, 41Rb of the dampers DL, DR are either the flow channel 44, the flow channel 46, the flow channels 61L, 61R, or the flow channel 47L, 47R, The pressure oil can move to each other through the flow channel 45.

Next, the relative positional relationship between the upper piston 3 and the lower piston 4 and the flow of pressure oil in the damper mechanisms DL and DR in one cycle whole process of the internal combustion engine will be described with reference to FIGS. .
Note that the rotation direction of the crank is clockwise (indicated by a circular arrow).

  First, the upper piston 3 and the lower piston 4 are in contact with each other at the top dead center which is the start of the intake process of FIG. As described above, since the extension portion 62 of the connecting portion 50 blocks the flow path 46, there is no pressure oil flow in the dampers DL and DR.

In FIG. 6, when the intake air advances and the inclination angle of the connecting rod 5 exceeds a predetermined value, the hydraulic circuits of the dampers DL and DR, that is, the flow paths are all in communication as described above. Since the intake air is being taken, the combustion chamber 9 has a negative pressure, and the upper piston 3 is subjected to a force to stay upward and an inertial force. On the other hand, since the lower piston 4 is connected to the crank 8 by the connecting rod 5, the lower piston 4 descends as the crank 8 rotates. Due to the inertial force and the negative pressure on the intake side, the upper piston 3 descends slightly behind the lower piston 4.
That is, the upper piston 3 and the lower piston 4 begin to separate from each other. When the upper piston 3 and the lower piston 4 begin to separate, the partition plates 34L and 34R in the hydraulic chambers 41L and 41R move upward, and the pressure oil in the hydraulic chamber flows from the upper chambers 41Lu and 41Ru to the flow paths 44, 46, and 61R. , 47R, 45, the pressure oil flows to the lower chambers 41Lb, 41Rb.

Here, since the buffer springs S are present in the upper chambers 41Lu and 41Ru (the reference numerals are not given in FIG. 6), the pistons 3 and 4 are not abruptly separated.
A little before the bottom dead center, the distance between the upper piston 3 and the lower piston 4 is decreasing due to the inertial force of the upper piston and the reaction force of the buffer spring S in the state where the hydraulic pressure is not applied through the hydraulic circuit. .

  At the bottom dead center where the intake process is changed to the compression process in FIG. 7, the oil in the lower chambers 41Lb and 41Rb is blocked from communicating with the upper chambers 41Lu and 41Ru for the reason described above. Therefore, the upper piston 3 and the lower piston 4 maintain a separated state against the inertial force that the upper piston 3 tends to descend.

  In the middle of the compression process of FIG. 8, the upper chambers 41Lu and 41Ru and the lower chambers 41Lb and 41Rb communicate with each other. That is, no hydraulic pressure is applied to the dampers DL and DR. Further, since the valves 13 and 14 are closed even when the air in the combustion chamber is compressed, the lower piston 4 approaches the upper piston 3, and eventually the upper piston 3 and the lower side slightly before the top dead center in FIG. The piston 4 is in close contact.

  9, the upper chambers 41Lu and 41Ru and the lower chambers 41Lb and 41Rb are again disconnected from the pressure oil. Even if the upper piston 3 tries to collide with the upper end of the combustion chamber 8 due to inertia, the pressure oil in the upper chambers 41Lu and 41Ru of the damper mechanism does not move and cannot be separated from the lower piston 4. Therefore, the upper piston 3 does not collide with the upper end of the combustion chamber 8.

  If the top dead center of FIG. 9 is passed and the compression process of FIG. 10 is entered, the pressure increase in the combustion chamber 9 becomes large due to explosion / expansion until the bottom dead center and the upper piston 3 lowers the lower piston 4 Therefore, the oil does not move from the upper chambers 41Lu and 41Ru to the lower chambers 41Lb and 41Rb. Therefore, the upper piston 3 and the lower piston 4 are integrally lowered.

As it is, the bottom dead center (FIG. 11) which is the end of the expansion stroke is passed, and the exhaust process of FIG. 12 is entered.
In the exhaust process, the exhaust valve 14 is open. Since the lower piston 4 pushes up the upper piston 3, they are not separated. When the top dead center is reached again (see FIG. 5), the piston 2 (the upper piston 3) does not collide with the upper end of the combustion chamber 9 for the same reason as in FIG.

  According to the internal combustion engine of the illustrated embodiment, the first piston (upper piston) 3 and the second piston (lower piston) 4 are separated in the intake stroke, and the second piston (lower piston) 4 is When the position closest to the crank 8 in the cylinder 1 is reached, the distance between the two reaches the maximum, and the upper piston 3 does not descend any further before reaching the bottom dead center. As a result, even if the intake valve 13 is not “closed quickly”, the time of the compression stroke is shortened. That is, the compression ratio is reduced.

In the next compression stroke, the separated upper piston 3 and lower piston 4 are close to each other, and at the end of the compression stroke, the upper piston 3 and the lower piston 4 are integrated. And since the expansion stroke and the exhaust stroke are performed in a state where the upper piston 3 and the lower piston 4 are integrated, the distance that the upper piston 3 moves in the cylinder 1 is larger than that in the intake stroke and the compression stroke. The distance is longer by the distance that the upper piston 3 and the lower piston 4 are separated from each other.
In other words, the volume of the gas expanded in the expansion stroke is increased by that amount, and the expansion ratio is increased.

  That is, according to the illustrated embodiment, it is possible to execute the mirror cycle without changing the closing timing of the intake valve 13 to reduce the compression ratio and increase the expansion ratio.

  Further, the speed of the lower piston 4 is not changed, but the speed of the upper piston 3 is decreased. Since the intake speed becomes slow, the intake resistance decreases. That is, the pumping loss can be further reduced.

  Since it is not necessary to perform the opening / closing operation of the intake valve 13 suddenly, the piston 2 (the upper piston 3) may interfere with the intake valve 13 when the intake valve 13 protrudes toward the combustion chamber 9 during intake. Disappear.

  Since it is not necessary to change the opening / closing timing of the intake valve 13 as in the case of the normal Otto cycle, it is possible to perform sufficient intake as compared with the conventional early closing type mirror cycle.

Since it is not necessary to shorten the time during which the intake valve 13 is opened, there is no need to increase the speed in the opening / closing operation of the intake valve 13 (the opening / closing operation is performed rapidly), and the intake valve 13 and the valve seat are burdened. There is no giving.
Further, since it is not necessary to make the cam have a “pointed” shape, the cam and the valve member that contacts the cam can be prevented from being worn or damaged.

  The intake air temperature does not rise because the blow-back phenomenon like the slow closing of the prior art does not occur. Therefore, the knocking avoidance ability is improved.

The illustrated embodiment is merely an example, and is not intended to limit the technical scope of the present invention.
For example, in the illustrated embodiment, pressure oil is used to bring the upper and lower pistons closer to or away from each other, but fluids other than pressure oil can be used. It is also possible to employ other mechanical means without using a fluid mechanism.

  The present invention can be effectively used for all industrial fields in which, for example, a four-cycle engine is used as a prime mover and high efficiency in the use is a priority item.

The elevation view which shows the whole structure of embodiment of this invention. The elevation view of the 1st (upper side) piston concerning the embodiment of the present invention. The elevation view of the 2nd (lower side) piston concerning the embodiment of the present invention. The partial detail drawing of the connecting rod which concerns on embodiment of this invention. The process figure which showed the state of the top dead center which changes from the exhaust process which concerns on embodiment of this invention to an intake process. The inhalation | air-intake process figure which concerns on embodiment of this invention. The process figure which showed the state of the bottom dead center which changes to the compression process from the intake process which concerns on embodiment of this invention. The compression process figure which concerns on embodiment of this invention. The process figure which showed the state of the top dead center which changes from the compression process which concerns on embodiment of this invention to an expansion process. The expansion process figure concerning the embodiment of the present invention. The process figure which showed the state of the bottom dead center which changes from the expansion | swelling process which concerns on embodiment of this invention to an exhaust process. FIG. 3 is an exhaust process diagram according to the embodiment of the present invention. The process figure which showed each process of the Otto cycle later on. The process figure which showed each process of the "late closing" mirror cycle by a prior art later on.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cylinder 2 ... Piston 3 ... 1st piston / upper piston 4 ... 2nd piston / lower piston 5 ... Connecting rod 6 ... Small end part 7 ... Large end 8 ... Crank 9 ... Combustion chamber 10 ... Cylinder head 11 ... Intake port 12 ... Exhaust port 13 ... Intake valve 14 ... Exhaust valves 33L, 33R ... Guide rods 34L, 34R ... partition plates 41L, 41R ... oil chambers 44 to 46, 47L, 47R ... flow paths 61L, 61R ... flow paths S ... buffer springs

Claims (3)

  In a four-cycle internal combustion engine that performs a mirror cycle, the piston is separated into a first piston close to the intake valve and a second piston close to the crank, or the first piston and the second piston are separated from each other. The first piston and the second piston are separated in the intake stroke, and the separated first piston and the second piston are close to each other in the compression stroke. In the internal combustion engine, the first piston and the second piston are integrally moved in the cylinder in the expansion stroke and the exhaust stroke.   When the first piston and the second piston are separated or close to each other, the rod for guiding the first piston is connected to a hydraulic damper mechanism provided on the second piston, and the hydraulic damper The mechanism is separated into a first chamber and a second chamber by a blocking member provided on the rod, and a pressurized liquid stored in the first chamber and the second chamber in the second piston. If the connecting rod is parallel to the piston moving direction, the first chamber and the second chamber are not communicated with each other, but if the connecting rod is inclined with respect to the piston moving direction. The internal combustion engine according to claim 1, wherein the first chamber and the second chamber are configured to communicate with each other.   A flow path through which the pressure fluid flows is also formed in the peripheral portion of the piston side end of the connecting rod connected to the piston, and the flow path formed in the peripheral portion of the connecting rod on the piston side is: If the connecting rod is parallel to the piston moving direction, it does not communicate with the flow path formed in the second piston, but if the connecting rod is inclined with respect to the piston moving direction, the flow formed in the second piston 3. The internal combustion engine according to claim 2, wherein the internal combustion engine is configured to communicate with the road and thereby communicate between the first chamber and the second chamber.

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