JP2020094506A - Variable compression ratio internal combustion engine - Google Patents

Abstract

To raise a compression ratio at a high load in order to further improve fuel economy, in a variable compression ratio internal combustion engine.SOLUTION: An internal combustion engine 1 lowers a compression ratio at an engine high load, and raises the compression ratio at an engine low load. The internal combustion engine 1 has an upper link 15 whose one end is connected to a piston pin 18, and the other end is rotatably connected to a crankpin 21 of a crankshaft 20, and which is connected to a lower link 16. The upper link 15 has a penetration hole 45 which is formed so as to make a lubricant injected from a lower link oil passage 51 in a piston ascending stoke at the engine high load pass therethrough, and to introduce the lubricant which has passed to a crown face backside at a side at which an exhaust valve 6 is located in a crankshaft axial view.SELECTED DRAWING: Figure 1

Description

The present invention relates to a variable compression ratio internal combustion engine using a multi-link piston crank mechanism.

For example, in Patent Document 1, an upper link connected to a piston via a piston pin and a lower link rotatably attached to a crank pin of a crankshaft and connected to the upper link via a first connecting pin. A link, a control link whose one end is connected to the lower link through a second connecting pin, and a control shaft rotatably attached to the cylinder block and having an eccentric shaft that supports the other end of the control link. And a compression ratio using a multi-link piston crank mechanism in which the first connecting pin is located on one side and the second connecting pin is located on the other side across the cylinder center axis. There is disclosed an internal combustion engine capable of changing the.

In such a variable compression ratio internal combustion engine, in order to further improve fuel efficiency, it is required to increase the compression ratio at high load and to expand the range thereof.

Japanese Patent No. 5983887

However, in Patent Document 1 described above, no countermeasure against knocking at high load is taken, and there is a possibility that knocking may occur if the compression ratio at high load is increased.

That is, in the conventional variable compression ratio internal combustion engine, there is room for further improvement in suppressing the knocking at the time of high load to improve the fuel consumption.

The present invention is a variable compression ratio internal combustion engine that has a low compression ratio at high engine load and a high compression ratio at low engine load, with one end connected to a piston pin and the other end rotated to a crankpin of a crankshaft. A first link that is connected to a second link that is operably connected, and the first link is injected from a second link oil passage formed in the second link during a piston ascending stroke during high engine load. It has a through hole formed so as to pass the lubricating oil and to guide the lubricating oil that has passed to the back side of the piston crown surface on the side where the exhaust valve is located when viewed in the crankshaft axial direction.

According to the present invention, it is possible to cool the exhaust valve side of the piston, which is more susceptible to knocking than the intake valve side of the piston, at the time of high engine load, and to further increase the compression ratio at high engine load. Is possible.

The explanatory view showing typically the variable compression ratio internal-combustion engine concerning the present invention. The explanatory view showing typically the variable compression ratio internal-combustion engine concerning the present invention. The explanatory view showing typically the variable compression ratio internal-combustion engine concerning the present invention. The perspective view of an upper link.

An embodiment of the present invention will be described below in detail with reference to the drawings. 1 to 3 are explanatory views schematically showing an internal combustion engine 1 to which the present invention is applied. FIG. 1 shows a state during an ascending stroke of a low compression ratio, and FIG. 2 shows a low compression ratio. The piston bottom dead center is shown, and FIG. 3 shows the high compression ratio. 1 to 3 schematically show an internal combustion engine 1 to which the present invention is applied when viewed in the axial direction of a crankshaft. FIG. 4 is a perspective view of the upper link 15 that constitutes the multi-link type piston crank mechanism 13 of the internal combustion engine 1 to which the present invention is applied.

The internal combustion engine 1, which is a variable compression ratio internal combustion engine, is mounted on a vehicle such as an automobile as a drive source, and has an intake passage 2 and an exhaust passage 3. The intake passage 2 is connected to the combustion chamber 5 via an intake valve 4. The exhaust passage 3 is connected to the combustion chamber 5 via an exhaust valve 6.

The internal combustion engine 1 has a multi-link type piston crank mechanism 13 capable of changing the mechanical compression ratio of the internal combustion engine 1 by changing the top dead center position of the piston 14 that reciprocates in the cylinder 12 of the cylinder block 11. doing. The mechanical compression ratio of the internal combustion engine 1 is a compression ratio determined by the top dead center position and the bottom dead center position of the piston 14.

The multi-link type piston crank mechanism 13 is roughly composed of a piston 14, an upper link 15 as a first link, a lower link 16 as a second link, and a control link 17 as a third link.

The piston 14 is rotatably connected to one end of an upper link 15 via a piston pin 18.

The other end of the upper link 15 is rotatably connected to one end of the lower link 16 via an upper pin 19 as a first connecting pin.

The lower link 16 is rotatably connected to the crank pin 21 of the crank shaft 20.

The rotation center of the crankshaft 20 is located closer to the intake valve 4 side than the cylinder center axis line L when viewed in the crankshaft axial direction.

One end of the control link 17 is rotatably connected to the other end side of the lower link 16 via a control pin 22 as a second connecting pin.

The control link 17 is rotatably connected to the eccentric shaft portion 23a of the control shaft 23, the other end of which is supported on the engine body side.

The control shaft 23 is arranged in parallel with the crankshaft 20, and is rotatably supported by, for example, a cylinder block (not shown).

That is, the other end of the control link 17, which is rotatably connected to the eccentric shaft portion 23a of the control shaft 23, is swingably supported on the engine body side. The central axis of the eccentric shaft portion 23a is eccentric by a predetermined amount with respect to the rotation center of the control shaft 23. The control shaft 23 regulates the degree of freedom of the lower link 16.

The multi-link type piston crank mechanism 13 includes a piston 14 and a crank pin 21 of a crank shaft 20 linked by a plurality of links.

The multi-link type piston crank mechanism 13 changes the position of the top dead center of the piston 14 by changing the position of the eccentric shaft portion 23a by rotating the control shaft 23, and changes the compression ratio of the internal combustion engine 1. be able to.

An oil pan upper 24 is attached to the lower portion of the cylinder block 11. An oil pan lower 25 is attached to the lower part of the oil pan upper 24.

The rotation of the drive shaft 29 is transmitted to the control shaft 23 via the first arm 26, the second arm 27, and the intermediate arm 28. The intermediate arm 28 connects the first arm 26 and the second arm 27. The drive shaft 29 is arranged outside the oil pan upper 24 and parallel to the control shaft 23. More specifically, the drive shaft 29 is arranged on the side where the intake valve 4 and the intake passage 2 are located. The first arm 26 is fixed to the drive shaft 29.

One end of an intermediate arm 28 is rotatably connected to the first arm 26 via a first pin member 30. The other end of the intermediate arm 28 is rotatably connected to the second arm 27 fixed to the control shaft 23 via the second pin member 31.

One ends of the drive shaft 29, the first arm 26, and the intermediate arm 28 are housed in a housing 32 attached to the side surface of the oil pan upper 24.

That is, the housing 32 is attached to the side surface of the oil pan upper 24 on the side where the intake valve 4 and the intake passage 2 are located.

One end of the drive shaft 29 is connected to an electric motor 33 as an actuator via a speed reducer (not shown). That is, the drive shaft 29 can be rotationally driven by the electric motor 33. The rotation speed of the drive shaft 29 is the rotation speed of the electric motor 33 reduced by a speed reducer.

The electric motor 33 is arranged on the side where the intake valve 4 and the intake passage 2 of the internal combustion engine 1 are located. Therefore, the electric motor 33 is unlikely to be affected by the heat of the exhaust gas flowing through the exhaust passage 3 of the internal combustion engine 1, and can suppress the occurrence of a failure due to the heat effect of the exhaust gas, for example.

When the drive shaft 29 is rotated by driving the electric motor 33, the intermediate arm 28 reciprocates along a plane orthogonal to the drive shaft 29. Then, as the intermediate arm 28 reciprocates, the connecting position between the intermediate arm 28 and the second arm 27 swings, and the control shaft 23 rotates. When the control shaft 23 rotates and its rotational position changes, the position of the eccentric shaft portion 23a, which is the swing fulcrum of the control link 17, changes. That is, by changing the rotational position of the control shaft 23 by the electric motor 33, the posture of the lower link 16 changes, and the machine of the internal combustion engine 1 changes with changes in the top dead center position and the bottom dead center position of the piston 14. The compression ratio is continuously changed. In other words, the electric motor 33 rotationally drives the control shaft 23 to change the position of the eccentric shaft portion 23a, thereby changing the mechanical compression ratio of the internal combustion engine 1.

The electric motor 33 is controlled so that the mechanical compression ratio of the internal combustion engine 1 becomes a compression ratio corresponding to operating conditions.

The target compression ratio of the internal combustion engine 1 is basically a high compression ratio on the low load side, and the higher the load, the lower the compression ratio for suppressing knocking and the like.

As shown in FIG. 4, the upper link 15 includes a rod portion 41 which is a long and slender rectangular column extending linearly, an annular piston pin pin boss portion 42 provided at one end of the rod portion 41, and a rod portion. And an annular upper pin pin boss portion 43 provided at the other end of 41. The upper pin pin boss portion 43 corresponds to the first connecting pin pin boss portion.

The rod portion 41 includes a first surface 41a and a second surface 41b that are parallel to a plane orthogonal to the crankshaft 20, a third surface 41c and a fourth surface 41d that are orthogonal to the first surface 41a and the second surface 41b. have.

The first surface 41a and the second surface 41b are the front surface and the back surface of the rod portion 41 when viewed in the crankshaft axial direction. The third surface 41c and the fourth surface 41d are one side surface and the other side surface of the rod portion 41 when viewed in the crankshaft axial direction.

The rod portion 41 is formed, for example, such that the width W1 of the first surface 41a and the second surface 41b is smaller (narrower) than the width W2 of the third surface 41c and the fourth surface 41d.

Rectangular recesses 44 are formed along the longitudinal direction of the rod portion 41 on the third surface 41c and the fourth surface 41d, which are the side surfaces of the rod portion 41, respectively. A through hole 45 having a rectangular cross section is formed in the recess 44.

The through hole 45 has one end opening to the bottom surface 44a of the recess 44 on the third surface 41c side and the other end opening to the bottom surface 44a of the recess 44 on the fourth surface 41d side. That is, the through hole 45 is an elongated hole along the longitudinal direction of the rod portion 41 and penetrates the side surface of the rod portion 41. The through hole 45 is formed on the piston pin pin boss portion 42 side of the rod portion 41.

The piston pin pin boss portion 42 constitutes one end of the upper link 15, and is rotatably fitted to the central portion of the piston pin 18 whose both ends are supported by the piston 14. The piston pin 18 may be press-fitted into the piston 14 and fixed, or may be rotatably supported by the piston 14 in a so-called full float type.

The upper pin pin boss portion 43 constitutes the other end of the upper link 15, and is rotatably fitted to the upper pin 19 whose both ends are supported by the lower link 16.

In the internal combustion engine 1, the upper pin 19 that connects the upper link 15 and the lower link 16 is located on one side across the cylinder center axis L in the crankshaft axial direction, and the lower link 16 and the control are connected to the other side. A control pin 22 connecting the link 17 is located.

Therefore, as viewed in the crankshaft axial direction, a thrust force that pushes the piston 14 against the inner peripheral surface of the cylinder on the side where the control link 17 is located acts on the piston 14. In other words, the piston 14 of the internal combustion engine 1 receives a thrust force that pushes the piston 14 against the cylinder inner peripheral surface on the side where the intake valve 4 is located, as viewed in the crankshaft axial direction.

In addition, in a variable compression ratio internal combustion engine such as the internal combustion engine 1, in order to further improve fuel efficiency, compression at high load (for example, when the internal combustion engine has a supercharger is supercharged) is compressed. It is necessary to increase the ratio and expand its operating range.

Knocking must be avoided in order to increase the compression ratio and expand the operating range at high load. The site where knocking occurs is the crown surface of the piston 14 on the exhaust valve side.

Therefore, the internal combustion engine 1 uses the attitude of the upper link 15 that changes depending on the difference in compression ratio, and mainly supplies the lubricating oil injected from the lower link oil passage 51 as the second link oil passage according to the compression ratio. Change the position (the hit position).

The lower link oil passage 51 is formed in the lower link 16. The lower link oil passage 51 is formed on the side where the intake valve 4 is located with respect to the connecting position between the upper link 15 and the lower link 16 as viewed in the crankshaft axial direction.

The lower link oil passage 51 communicates with the crankpin oil passage 52 formed in the crankpin 21 when the lower link 16 is in a predetermined swing posture, and the lubricating oil flowing from the crankpin oil passage 52 is connected to the upper link 15 It is formed so as to jet toward.

The crankpin oil passage 52 is a passage extending along the radial direction of the crankpin 21, and communicates with a main gallery (not shown) through an oil passage (not shown) formed in the crankshaft.

The upper link 15 allows the lubricating oil injected from the lower link oil passage 51 to pass through during the piston ascending stroke when the engine has a high load, and the passing lubricating oil is located on the side where the exhaust valve 6 is located when viewed in the crankshaft axial direction. It has a through hole 45 leading to the back side of the crown surface.

The through hole 45 is formed so that the lubricating oil passing through itself in the piston ascending stroke at the time of high engine load is supplied to the rear side of the piston crown surface on the side where the exhaust valve 6 is located as viewed in the crankshaft axial direction.

That is, in the internal combustion engine 1, the lubricating oil injected from the lower link oil passage 51 penetrates the upper link 15 as shown by the arrow A in FIG. 1 in the piston ascending stroke when the compression ratio setting is a low compression ratio. After passing through the hole 45, the gas can be supplied to the back side of the piston crown surface on the side where the exhaust valve 6 is located as viewed in the crankshaft axial direction.

The lower link oil passage 51 and the crankpin oil passage 52 are set to communicate with each other during the piston ascending stroke at the time of high engine load where the compression ratio is set low. That is, the lower link oil passage 51 communicates with the crankpin oil passage 52 and injects the lubricating oil toward the upper link 15 in the piston ascending stroke at the time of high engine load when the compression ratio is set low.

It should be noted that the through hole 45 does not have to pass all the lubricating oil injected from the lower link oil passage 51 in the piston ascending stroke at the time of high engine load. In other words, the through hole 45 may be located at a position where a part of the lubricating oil injected from the lower link oil passage 51 does not pass in the piston ascending stroke at the time of high engine load. That is, the upper link 15 reflects a part of the lubricating oil injected from the lower link oil passage 51 in the piston ascending stroke at the time of high engine load, and for example, the cylinder on the side where the intake valve 4 is located when viewed in the crankshaft axial direction. It may be supplied to the inner peripheral surface or the back side of the piston crown surface on the side where the intake valve 4 is located when viewed in the axial direction of the crankshaft.

As a result, the internal combustion engine 1 can cool the exhaust valve side of the piston 14 where knocking is likely to occur at the time of high engine load, and knocking can be improved. Therefore, the internal combustion engine 1 can further increase the compression ratio at the time of high engine load, and can further improve the fuel consumption. In addition, the internal combustion engine 1 can expand the operating range when the engine load is high.

Since the internal combustion engine 1 can supply the lubricating oil to the back side of the piston crown surface on the side where the exhaust valve 6 is located at the time of high engine load, the heat load of the piston 14 at the time of high engine load can be reduced. Therefore, in the internal combustion engine 1, the weight of the piston 14 can be reduced, and the cost reduction (reduction) due to the weight reduction can be achieved.

The internal combustion engine 1 can reduce the weight of the upper link 15 by providing the rod portion 41 with the recess 44 and the through hole 45.

In addition, the internal combustion engine 1 can reduce the surface pressure acting on the bush used in the multi-link piston crank mechanism 13 by reducing the weight of the piston 14 and the upper link 15, and thus the cost can be reduced (reduced). Become.

In the internal combustion engine 1, since the lubricating oil is injected toward the upper link 15 only at the timing when the lower link oil passage 51 and the crankpin oil passage 52 communicate with each other, an appropriate amount of the lubricating oil is discharged to the exhaust valve 6 at an appropriate timing. Can be supplied to the back side of the piston crown surface on the side where the is located.

Further, the upper link 15 reflects the lubricating oil injected from the lower link oil passage 51 at the time of high engine load in which the piston 14 is located near the bottom dead center, and sucks the reflected lubricating oil in the crankshaft axial direction. It is formed so as to lead to the inner peripheral surface of the cylinder on the side where the valve 4 is located. In other words, the through hole 45 is formed at a position where the lubricating oil injected from the lower link oil passage 51 does not hit when the piston 14 is located near the bottom dead center and the engine has a high load.

That is, the internal combustion engine 1 reflects the lubricating oil injected from the lower link oil passage 51 at the time of high engine load in which the piston 14 is located near the bottom dead center, and The reflected lubricating oil can be supplied to the cylinder inner peripheral surface on the side where the intake valve 4 is located.

The lower link oil passage 51 and the crankpin oil passage 52 are set to communicate with each other at the timing when the piston 14 is positioned near the bottom dead center when the engine has a high load in which the compression ratio is set low. That is, the lower link oil passage 51 communicates with the crankpin oil passage 52 and lubricates toward the upper link 15 even when the piston 14 is located near the bottom dead center when the engine has a high compression load and the compression ratio is set low. Spray oil.

The upper link 15 does not have to reflect all the lubricating oil injected from the lower link oil passage 51 when the piston 14 is located near the bottom dead center and the engine has a high load. In other words, the through hole 45 may be located at a position where a part of the lubricating oil injected from the lower link oil passage 51 passes when the piston 14 is located near the bottom dead center and the engine has a high load. Alternatively, when the piston 14 is located near the bottom dead center and the engine is under a high load, part of the lubricating oil injected from the lower link oil passage 51 passes through the through hole 45, and the exhaust valve is viewed in the crankshaft axial direction. It may be at a position where it can be supplied to the back side of the piston crown surface on the side where 6 is located.

In the specification of the application, "the piston 14 is located near the bottom dead center" means that the piston 14 is located between the bottom dead center and a position near the bottom dead center that is higher than the bottom dead center by a predetermined amount. Shall mean. That is, "near the piston bottom dead center" is a concept including the piston bottom dead center.

As a result, the internal combustion engine 1 can supply the lubricating oil to the cylinder inner peripheral surface on the side to which the piston 14 is pressed when the load is high, and can suppress the scuffing of the piston 14.

The upper link 15 reflects the lubricating oil injected from the lower link oil passage 51 at the time of low engine load, and transfers the reflected lubricating oil to the cylinder inner peripheral surface on the side where the intake valve 4 is located when viewed in the crankshaft axial direction. It is formed to guide. In other words, the through hole 45 is formed at a position where the lubricating oil injected from the lower link oil passage 51 does not hit when the engine load is low.

That is, the internal combustion engine 1 reflects the lubricating oil injected from the lower link oil passage 51 at the time when the engine load is low and the intake valve 4 positions the reflected lubricating oil as shown by the arrow C in FIG. It is possible to supply to the inner peripheral surface of the cylinder on the side where the operation is performed.

The upper link 15 may not reflect all the lubricating oil injected from the lower link oil passage 51 when the engine load is low. In other words, the through hole 45 may be located at a position where a part of the lubricating oil injected from the lower link oil passage 51 passes when the engine load is low. Alternatively, through the through hole 45, at the time of low engine load, part of the lubricating oil injected from the lower link oil passage 51 passes and is supplied to the back side of the piston crown surface on the exhaust valve 6 side as viewed in the crankshaft axial direction. It may be in a possible position.

As a result, when the compression ratio of the internal combustion engine 1 is low (when the compression ratio is low), lubricating oil can be supplied to the cylinder inner peripheral surface on the side where the piston 14 is pressed, and the scuffing of the piston is suppressed. can do.

The upper link 15 reflects the lubricating oil injected from the lower link oil passage 51 at the time of low engine load and supplies the lubricating oil to the back side of the piston crown surface on the side where the intake valve 4 is located when viewed in the axial direction of the crankshaft. May be. Further, the upper link 15 reflects the lubricating oil injected from the lower link oil passage 51 at the time of low engine load, and the inner peripheral surface of the cylinder on the side where the intake valve 4 is located and the intake valve 4 when viewed in the axial direction of the crankshaft. You may make it supply to the piston crown surface back side in which it is located.

In this case, the internal combustion engine 1 can supply the lubricating oil reflected by the upper link 15 to the back side of the piston crown surface when the engine load is low, and can suppress the rise in piston temperature.

Further, the upper link 15 reflects the lubricating oil injected from the lower link oil passage 51 at the time of high engine load in which the piston 14 is located near the bottom dead center, and the intake valve 4 is located in the crankshaft axial direction. The piston may be supplied to the back side of the crown surface. Further, the upper link 15 reflects the lubricating oil injected from the lower link oil passage 51 at the time of high engine load in which the piston 14 is located near the bottom dead center, and the intake valve 4 is located in the crankshaft axial direction. It may be supplied to the inner peripheral surface of the cylinder and the back side of the piston crown surface on the side where the intake valve 4 is located.

When the compression ratio of the internal combustion engine 1 is high (when the compression ratio is high), the piston temperature rises as much as the compression ratio becomes higher than when the compression ratio is low. Therefore, the internal combustion engine 1 can suppress the rise in the piston temperature by supplying the lubricating oil reflected by the upper link 15 to the back side of the piston crown surface in such a situation (when the engine has a high load).

Further, the upper link 15 uses at least one of the rod portion 41, the piston pin pin boss portion 42, and the upper pin pin boss portion 43 when reflecting the lubricating oil injected from the lower link oil passage 51. is there.

DESCRIPTION OF SYMBOLS 1... Internal combustion engine 11... Cylinder block 12... Cylinder 13... Multi-link type piston crank mechanism 14... Piston 15... Upper link 16... Lower link 20... Crank shaft 21... Crank pin 41... Rod part 44... Recess 45... Through hole 51 … Lower Link Oilway

Claims (4)

A first link whose one end is connected to the piston via a piston pin,
A second link connected to the other end of the first link via a first connecting pin and rotatably connected to a crankpin of a crankshaft;
A third link whose one end is connected to the second link via a second connecting pin;
A control shaft rotatably attached to the engine body side and having an eccentric shaft portion to which the other end of the third link is connected;
An actuator that rotationally drives the control shaft to change the position of the eccentric shaft portion of the control shaft so that the compression ratio becomes low when the engine high load and becomes high when the engine low load,
The second link has a second link oil passage that communicates with a crankpin oil passage formed along the radial direction of the crankpin in a piston rising stroke and injects lubricating oil toward the first link. ,
The first link allows the lubricating oil injected from the second link oil passage to pass in the piston ascending stroke at the time of high engine load, and is directed to the rear side of the piston crown surface on the side where the exhaust valve is located in the crankshaft axial direction. A variable compression ratio internal combustion engine having a through hole formed so as to guide the lubricating oil that has passed therethrough. The variable compression ratio internal combustion engine is configured such that the first connecting pin is located on one side and the second connecting pin is located on the other side with the cylinder center axis line therebetween, as viewed in the crankshaft axial direction.
The first link reflects the lubricating oil injected from the second link oil passage when the engine load is low, and supplies the lubricating oil to the inner peripheral surface of the cylinder on the side where the intake valve is located when viewed in the crankshaft axial direction. The variable compression ratio internal combustion engine according to claim 1. The first link reflects the lubricating oil injected from the second link oil passage when the engine has a low load, and supplies the lubricating oil to the back side of the piston crown surface on the side where the intake valve is located when viewed in the axial direction of the crankshaft. The variable compression ratio internal combustion engine according to claim 1 or 2. The variable compression ratio internal combustion engine is configured such that the first connecting pin is located on one side and the second connecting pin is located on the other side with the cylinder center axis line therebetween, as viewed in the crankshaft axial direction.
The first link reflects the lubricating oil injected from the second link oil passage in the vicinity of the piston bottom dead center at the time of high engine load, and the cylinder inner peripheral surface on the side where the intake valve is located when viewed in the crankshaft axial direction. The variable compression ratio internal combustion engine according to claim 1, wherein the variable compression ratio internal combustion engine is supplied to the internal combustion engine.

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