JP6981929B2 - Internal combustion engine - Google Patents

Description

The present invention relates to an internal combustion engine.

Patent Document 1 discloses an internal combustion engine in which a large piston and a small piston are provided in one cylinder, and the change characteristic of the combustion volume in the expansion stroke can be changed. Specifically, a cylinder is further provided inside the large piston, and the small piston is slidably arranged in the cylinder. A slidable cam is provided on the connecting rod connected to the large piston, and the cam swings left and right due to the vertical movement of the large piston, and the small piston is driven up and down in the cylinder of the large piston.

In the internal combustion engine, the movement of the small piston reduces the rate of increase in the combustion chamber volume in the first half of the expansion stroke, and increases the rate of increase in the combustion chamber volume in the latter half. As a result, the slow heat generation due to post-combustion in the latter half of the expansion stroke is converted into effective work, and the effect of improving the thermal efficiency can be obtained.

Japanese Unexamined Patent Publication No. 60-216053

However, the conventional internal combustion engine simply changes the rate of increase in the combustion chamber volume in the expansion stroke, and cannot change the compression ratio. Therefore, there is room to further improve the thermal efficiency by making the compression ratio changeable.

In view of the above-mentioned conventional drawbacks, an object of the present invention is to provide an internal combustion engine capable of arranging two pistons in one cylinder to change the compression ratio and improving thermal efficiency. do.

In order to achieve the above object, the present invention has a large piston slidably arranged in a large cylinder and having a small cylinder, a large connecting rod connecting the large piston and the crankpin of the crankshaft, and the small. A small piston slidably arranged in a cylinder, a small connecting rod connecting the small piston and the large connecting rod, and a small conrod provided on the crank arm of the crankshaft, abutting on the small conrod and contacting the large connecting rod. On the other hand, it is characterized by including an abutting body that changes the position of the small connecting rod and a guide that guides the movement locus of the corresponding contact body.

In the above configuration, the guide may abut on a part of the movement locus of the abutting body.

Further, in the above configuration, the contact start position between the contact body and the guide may be changed.

In the above configuration, the contact portion of the contact body with the guide may be provided at the end of the contact body.

Further, in the above configuration, the contact body is a rod-shaped member, and the end portion of the contact body opposite to the contact portion with the guide may be pivotally supported by the crank arm. good.

In the above configuration, the contact body includes a first contact portion that contacts the small connecting rod, a second contact portion that contacts the guide, the first contact portion, and the second contact portion. A rod portion connecting to the abutting portion may be provided, and the rod portion may be supported by penetrating the crank arm and slidable in the crank arm within a certain range.

Further, in the above configuration, the guide guides the first guide surface for guiding the abutting body before reaching the top dead center of the crank arm, and the abutting body after the top dead center of the crank arm. A second guide surface may be provided, and a driving force may be generated in the crank arm by a reaction force received by the abutting body from the second guide surface.

According to the present invention, it is possible to provide an internal combustion engine in which two pistons are arranged in one cylinder so that the compression ratio can be changed and the thermal efficiency is improved.

It is a partial sectional front view which shows the structure of the main part of the internal combustion engine which concerns on 1st Embodiment of this invention. It is also a partial cross-sectional side view showing the configuration of a main part of an internal combustion engine. It is a figure which shows the structure of the push arm and the guide which concerns on 1st Embodiment. It is a figure which shows the displacement state of a small connecting rod by a push arm. It is a figure which shows the change of the top dead center position of a small piston by a guide. It is a schematic diagram which shows the behavior of a small connecting rod at the time of combustion. It is a partial sectional front view which shows the structure of the main part of the internal combustion engine which concerns on 2nd Embodiment of this invention. It is a partial cross-sectional side view which shows the structure of the main part of the internal combustion engine which concerns on 2nd Embodiment. It is a figure which shows the contact start state of a contact body and a small connecting rod in 2nd Embodiment. It is a figure which shows the change of the top dead center position of a small piston by the guide of the internal combustion engine which concerns on 2nd Embodiment. It is a schematic diagram which shows the behavior of the small connecting rod at the time of combustion of the internal combustion engine which concerns on 2nd Embodiment.

Hereinafter, the present invention will be described with reference to the drawings.
First, the overall configuration of the internal combustion engine 1 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 4.
FIG. 1 is a partial cross-sectional view showing the configuration of a main part of the internal combustion engine 1 according to the first embodiment of the present invention, and FIG. 2 is a partial cross-sectional side view showing the configuration of the main part of the internal combustion engine 1 as well. FIG. 3 is a diagram showing the configuration of the push arm 10 and the guide 11, and FIG. 4 is a diagram showing a displacement state of the small connecting rod 9 by the push arm 10. In the figure, UP indicates an upper direction.

The internal combustion engine 1 includes a cylinder block 3 having a large cylinder 2 and a crankcase 4 mounted on the lower portion of the cylinder block 3. A large piston 7 is slidably provided in the large cylinder 2, and a small cylinder 71 is provided in the large piston 7. A small piston 8 is slidably provided on the small cylinder 71.
A small connecting rod 9 is connected to the small piston 8, and the position of the small piston 8 with respect to the large piston 7 can be changed by contacting the push arm 10, which is a contact body described later. The large cylinder 2 and the small cylinder 71 communicate with each other at the upper part of the large piston 7, and the large cylinder 2 and the small cylinder 71 are provided so as to extend in parallel.

The large piston 7 is connected to the crankshaft 5 by a large connecting rod 6, and the crankshaft 5 rotates as the large piston 7 reciprocates up and down in the large cylinder 2 due to the explosion of fuel in the combustion chamber. It is configured to be driveable. In FIG. 1, the crankshaft 5 of the internal combustion engine 1 rotates in the rotation direction R.
The crankshaft 5 includes a crank journal 51, a crank arm 52, a crank pin 53, and a counterweight 54. The crank journal 51 serves as a rotation shaft of the crankshaft 5, and the crank journal 51 is rotatably supported by the cylinder block 3 and the crankcase 4 by bearings (not shown).

The crank arm 52 connects the crank journal 51 and the crank pin 53, extends in a direction orthogonal to the crank journal 51, and connects to the crank pin 53. The base portion 6b of the large connecting rod 6 is rotatably connected to the crankpin 53, and the crankpin 53 is integrally connected to the crank journal 51 by the crank arm 52. Then, the crankpin 53 moves on the circumference centered on the crank journal 51 due to the rotation of the crank arm 52.
Further, the crankshaft 5 is provided with a counterweight 54 extending in a direction opposite to the extending direction of the crank arm 52.

As shown in FIG. 2, the large connecting rod 6 is composed of two blades 6a and a base 6b. The two blades 6a are each connected to the piston pin 7a of the large piston 7 at the upper part, and the blades 6a are connected to the base 6b in a state of being connected to each other at the lower part thereof. Both the blade 6a and the base portion 6b are configured to be wide in a direction orthogonal to the rotation axis of the crankshaft 5.
The base portion 6b of the large connecting rod 6 is provided with a groove portion 61 along the extending direction of the large connecting rod 6. The groove portion 61 is provided on the surface of the base portion 6b that is orthogonal to the rotation axis direction of the crankshaft 5. The roller 93 of the small connecting rod 9 is inserted into the groove 61 with play, and the roller 93 is configured to be slidable in the groove 61.

The small connecting rod 9 is composed of an upper portion 91, a cage 92, two rollers 93, and two contact rollers 94. The upper end of the upper portion 91 is connected to the small piston 8, and the lower end of the upper portion 91 is connected to the upper portion of the cage 92. Further, the upper portion 91 is arranged between the blades 6a of the large connecting rod 6.

The cage 92 of the small connecting rod 9 is composed of a top beam 92a, two triangular plates 92b, and two bottom beams 92c. The upper portion 91 is connected to the central portion of the upper surface of the top beam 92a, and as shown in FIG. 1, both ends of the top beam 92a are located outside between the blades 6a of the large connecting rod 6. The upper portions of the triangular plates 92b are connected to both ends of the top beam 92a, and the blades 6a and the base 6b of the large connecting rod 6 are arranged between the triangular plates 92b.
As shown in FIG. 2, the triangular plate 92b is configured in the shape of a substantially isosceles triangle, is connected to the top beam 92a at the apex angle portion, and is connected by two bottom beams 92c at the bottom portion. Then, the two bottom beams 92c are arranged so as to sandwich the base portion 6b of the large connecting rod 6.

A roller 93 is rotatably attached to the bottom beam 92c of the cage 92 inside the cage 92, and the roller 93 is engaged with the groove 61 of the large connecting rod 6. The rotation axis direction of the roller 93 coincides with the rotation axis direction of the crankshaft 5, and the resistance when the small connecting rod 9 slides with respect to the large connecting rod 6 is reduced. As a result, the lower part of the small connecting rod 9 is held in a slidable state by the lower part of the large connecting rod 6. The bottom beam 92c extends in the width direction of the large connecting rod 6, and the roller 93 is provided at the center of the bottom beam 92c.

A contact rollers 94 are provided on the outer surface of the bottom beam 92c, which is the outer side of the cage 92. As shown in FIG. 1, in the cage 92, one of the bottom beams 92c extends downward, and the contact roller 94 is arranged at the portion extending downward.
Then, the contact roller 94 is arranged offset with respect to the arrangement position of the roller 93 in the bottom beam 92c. In the present embodiment, the contact roller 94 is arranged at the end of the bottom beam 92c and is offset with respect to the roller 93 in the direction opposite to the rotation direction of the crankshaft 5. As a result, the contact roller 94 protrudes from the cage 92 and is configured to be able to contact the push arm 10.

The push arm 10 is a rod-shaped member provided on the crank arm 52 so as to be swingable. The push arm 10 is an abutting body that abuts on the small connecting rod 9 in order to regulate the position of the small connecting rod 9 with respect to the large connecting rod 6.
As shown in FIGS. 3 and 4, the push arm 10 is rotatably provided on the crank arm 52 of the crankshaft 5 within a certain range. The direction of the rotation axis of the push arm 10 coincides with the direction of the rotation axis of the crankshaft 5.
A pivotal branch 10a is provided at one end of the push arm 10. As shown in FIG. 2, a pin 10e penetrating the crank arm 52 and the crank pin 53 is inserted into the pivot portion 10a. As a result, the push arm 10 is swingably supported with respect to the crank arm 52 with the pin 10e as the center.
The push arm 10 is attached to both ends of the pin 10e, and is pivotally supported by the pin 10e with respect to the crank arm 52. Further, the two push arms 10 are arranged so as to sandwich the large connecting rod 6.

As shown in FIG. 2, a guide roller 10c is provided at the tip portion 10b on the opposite side of the pivot portion of the push arm 10. The contact roller 94 of the small connecting rod 9 is located on the rotation plane of the push arm 10, and the contact roller 94 can come into contact with the push arm 10.

The rotation range of the push arm 10 is restricted to a certain range by the shape of the crank arm 52. As shown in FIG. 3, the crank arm 52 is provided with a first regulation surface 52a and a second regulation surface 52b.
A protrusion 10d extends from the pivot portion 10a of the push arm 10, and the protrusion 10d abuts on the first regulation surface 52a to restrict the clockwise rotation of the push arm 10. Then, when the push arm 10 comes into contact with the second regulating surface 52b between the guide roller 10c and the pivot portion 10a, the rotation of the push arm 10 in the counterclockwise direction is restricted.

The movement locus of the push arm 10 is guided by the guide 11 attached to the cylinder block 3. The movement locus of the push arm 10 is changed by changing the deployment angle, which is the angle formed by the extension direction of the crank arm 52 and the extension direction of the push arm 10.
When the guide roller 10c of the push arm 10 comes into contact with the guide 11, the push arm 10 is rotated with respect to the crank arm 52.
The guide 11 is composed of a rod 11a, a rail portion 11b, and an actuator 11c. A rail portion 11b is provided at the tip of the rod 11a. The rod 11a is arranged in a direction orthogonal to the crank journal 51 with the end on the crank journal 51 side facing upward. Then, by introducing the guide roller 10c into the groove portion 11d provided in the rail portion 11b, the rotation position of the push arm 10 with respect to the crank arm 52 is changed.

As shown in FIG. 3, the actuator 11c of the guide 11 makes the rod 11a slidable, and the actuator 11c changes the position of the rail portion 11b. The groove portion 11d of the rail portion 11b is an arcuate groove, and the groove portion 11d has a shape that is convex toward the adjacent cylinder block side. Then, the guide roller 10c of the push arm 10 is fitted in the groove portion 11d of the rail portion 11b so that the guide roller 10c can pass through the rail portion 11b.

In the rail portion 11b of the guide 11, the groove portion 11d is configured to be wide on the upstream side in the rotation direction of the crankshaft 5, and the guide roller 10c can be introduced into the groove portion 11d within the movable range of the rail portion 11b. ing.
Further, in the rail portion 11b, a guide surface 11e is provided on the surface on the crank journal 51 side, and is connected to the lower portion of the groove portion 11d on the downstream side in the rotation direction of the crankshaft 5.
Then, after the guide roller 10c passes through the groove portion 11d on the downstream side in the rotation direction of the crankshaft 5, it can come into contact with the guide surface 11e.

The rail portion 11b can change the trajectory of the guide roller 10c of the push arm 10 with respect to the crank journal 51 which is the rotation axis of the crankshaft 5.
When the rod 11a is extended, the downstream side of the groove portion 11d in the rotation direction of the crankshaft 5 is separated from the crank journal 51. As a result, as shown by the solid line in FIG. 4, the push arm 10 rotates so that the guide roller 10c is separated from the crank journal 51.
When the rod 11a is housed in the actuator 11c, the downstream side of the groove portion 11d of the crankshaft 5 in the rotation direction approaches the crank journal 51. As a result, as shown by the alternate long and short dash line in FIG. 3, the guide roller 10c is brought closer to the crank journal 51.
In this way, the guide 11 makes it possible to change the position through which the guide roller 10c of the push arm 10 passes.

The push arm 10 abuts on the contact roller 94 of the small connecting rod 9, and the position of the small connecting rod 9 with respect to the large connecting rod 6 is changed depending on the deployment angle of the push arm 10 with respect to the crank arm 52.
In FIG. 4, the state shown by the two-dot chain line indicates the state in which the deployment angle of the push arm 10 is the minimum, and the state shown by the solid line indicates the state in which the deployment angle of the push arm 10 is the maximum. In the state shown by the alternate long and short dash line, the push arm 10 is in contact with the second regulation surface 52b, and in the state shown by the solid line, the push arm 10 is in contact with the first regulation surface 52a.

As shown in FIG. 4, when the guide roller 10c of the push arm 10 rotates in the direction away from the crank journal 51, the contact roller 94 moves upward by the push arm 10. As a result, the small connecting rod 9 moves upward, and the small piston 8 moves upward.
Then, when the guide roller 10c rotates in the direction approaching the crank journal 51, the contact roller 94 moves downward. As a result, the small piston 8 moves downward.
As the crank arm 52 rotates, the contact roller 94 that comes into contact with the push arm 10 moves from the pivot portion 10a side of the push arm 10 toward the guide roller 10c side.

In the above configuration, it is also possible to provide a plurality of large cylinders 2 in the cylinder block 3, arrange a large piston 7 having a small piston 8 in each, and connect them by a crankshaft 5 to form a multi-cylinder internal combustion engine.

Next, the operation of the first embodiment of the present invention will be described.
FIG. 5 is a diagram showing a change in the top dead center position of the small piston 8 by the guide 11. FIG. 6 is a schematic diagram showing the behavior of the small connecting rod 9 during combustion.
In the internal combustion engine 1, when the crankshaft 5 rotates, the push arm 10 rotates around the crank journal 51 together with the crank arm 52.

When the crank arm 52 rotates from the bottom dead center position, the large connecting rod 6 moves upward by the crank arm 52, and the large piston 7 moves upward in the large cylinder 2.
Then, the push arm 10 rotates upward together with the crank arm 52.
The rail portion 11b of the guide 11 is arranged on the movement locus of the guide roller 10c of the push arm 10 and abuts on the guide roller 10c.
The crank arm 52 abuts on the guide roller 10c within a range located near the top dead center. The range in which the rail portion 11b abuts on the guide roller 10c can be a phase range of 90 degrees before and after including the top dead center of the crank arm 52, and can be appropriately set within this range.

As the crank arm 52 rotates toward the top dead center, the guide roller 10c is introduced into the groove portion 11d of the rail portion 11b. Then, with the guide roller 10c engaged with the rail portion 11b, the push arm 10 is pulled by the crank arm 52 and rotates.
At this time, the push arm 10 enters below the small connecting rod 9 from the pivot portion 10a side, rotates with respect to the crank arm 52 around the pivot portion 10a due to the shape of the groove portion 11d, and the deployment angle is changed. To.
Before the guide roller 10c is introduced into the rail portion 11b, the push arm 10 rotates together with the crank arm 52 in a state of being directed in the extending direction of the crank arm 52 by centrifugal force.

When the crank arm 52 rotates from the bottom dead center to the top dead center, the small connecting rod 9 is moved upward by the large connecting rod 6 with the roller 93 in contact with the lower end of the groove portion 61 of the large connecting rod 6. Pushed up to.
Then, as the crank arm 52 further rotates, the push arm 10 enters below the small connecting rod 9, and the small connecting rod 9 is started to be pushed up.

In a state where the guide roller 10c is engaged with the rail portion 11b, the contact roller 94 of the small connecting rod 9 begins to abut between the pivot portion 10a of the push arm 10 and the guide roller 10c. As the crank arm 52 rotates, the contact roller 94 is pushed upward by the push arm 10, and the position of the small connecting rod 9 with respect to the large connecting rod 6 is restricted. Then, the position of the small piston 8 with respect to the large piston 7 is regulated via the small connecting rod 9.
At this time, the push arm 10 supports the contact roller 94 while being supported by the pivot portion 10a and the rail portion 11b. Then, since the push arm 10 abuts on the contact roller 94 from the pivot portion 10a side, most of the load at the start of contact is received by the pivot portion 10a.
Further, by providing the push arm 10 on the crank arm 52 located in the vicinity of the small connecting rod 9, the total length of the push arm 10 can be shortened. Then, since the small connecting rod 9 is pushed up while both ends of the push arm 10 are supported, the bending moment generated in the push arm 10 can be reduced.

In such a configuration, by changing the position of the push arm 10, the volume of the combustion chamber in the internal combustion engine 1 can be changed and the compression ratio can be changed.
In FIG. 5, H, M, and L indicate the internal combustion engine 1 in a high compression ratio state, an intermediate state, and a low compression ratio state, respectively.
In the state H, the rail portion 11b is moving upward, whereby the push arm 10 rotates upward. The small connecting rod 9 is moved upward by the push arm 10.
By holding the rail portion 11b of the guide 11 at the highest position within the set range, the guide roller 10c passes through the trajectory at the highest position, and the small connecting rod 9 supports the small piston 8 at the highest position.
That is, in the compression process of the large piston 7, the small piston 8 is supported at the highest position. As a result, the volume formed by the large cylinder 2, the large piston 7, the small cylinder 71 and the small piston 8 becomes small, and the compression ratio of the combustion chamber in the internal combustion engine 1 becomes high.

In the state L, the rail portion 11b is moved downward, whereby the push arm 10 is rotated downward. The small connecting rod 9 moves upward along the push arm 10.
By holding the rail portion 11b at the lowest position within the set range, the guide roller 10c passes through the trajectory at the lowest position, the small connecting rod 9 is pushed up to the lowest position, and the small piston 8 is pushed up to the lowest position.
As a result, the volume formed by the large cylinder 2, the large piston 7, the small cylinder 71 and the small piston 8 is large, and the compression ratio is low.

Further, the internal combustion engine 1 can also adjust the compression ratio between the states H and the state L as shown in the state M.
As described above, in the present embodiment, the height of the rail portion 11b can be changed between the state H and the state L, and the position of the small piston 8 can be changed and the compression ratio can be changed as needed. It has become.

Next, the action at the time of combustion will be described.
In FIG. 6, A indicates a state immediately before the top dead center position, and B indicates a state at the time of combustion.
As shown in FIG. 6, in the state A, the guide roller 10c is engaged with the groove portion 11d, and the height position of the small piston 8 with respect to the large connecting rod 6 is restricted upward by the push arm 10.
Then, when the crank arm 52 passes the top dead center, the guide roller 10c of the push arm 10 passes through the groove portion 11d.

When combustion is started with the small connecting rod 9 in contact with the push arm 10, the small connecting rod 9 pushes down the push arm 10 by combustion. As a result, the guide roller 10c that has passed through the groove portion 11d is pressed against the guide surface 11e of the rail portion 11b. In the state B, the guide roller 10c moves downward along the guide surface 11e from the position indicated by the alternate long and short dash line. As a result, a driving force is generated in the pivotal support portion 10a of the push arm 10 in the direction in which the crank arm 52 is rotated.

As described above, according to the first embodiment of the present invention, the internal combustion engine 1 is slidably arranged in the large cylinder 2, and has a large piston 7 having a small cylinder 71 and a large piston 7. A large connecting rod 6 for connecting the crank pin 53 of the crankshaft 5 is provided. Further, the internal combustion engine 1 includes a small piston 8 slidably arranged in the small cylinder 71, and a small connecting rod 9 connecting the small piston 8 and the large connecting rod 6. The internal combustion engine 1 is provided on the crank arm 52 of the crankshaft 5, and has a push arm 10 (corresponding to an abutting body) that abuts on the small connecting rod 9 and changes the position of the small connecting rod 9 with respect to the large connecting rod 6. Be prepared. Further, the internal combustion engine 1 includes a guide 11 that guides the movement locus of the push arm 10.
Therefore, the height position of the small connecting rod 9 by the push arm 10 can be set by the guide 11. The height position of the small connecting rod 9 can be adjusted with a simple configuration. Further, since the push arm 10 is provided on the crank arm 52, it becomes easy to move the small piston 8 in synchronization with the large piston 7. As a result, in the internal combustion engine 1 having the large piston 7 and the small piston 8 in one cylinder 2, the compression ratio can be changed and the thermal efficiency can be improved.

Further, the guide 11 comes into contact with a part of the movement locus of the push arm 10.
Therefore, the contact resistance between the push arm 10 and the guide 11 can be reduced, and the work efficiency of the internal combustion engine 1 can be improved. In addition, noise due to contact can be reduced, and the durability of the configuration for changing the compression ratio can be improved.

Further, the contact start position between the push arm 10 and the guide 11 can be changed.
Therefore, the height position of the small connecting rod 9 can be changed by a simple configuration. Further, the timing at which the push arm 10 receives the contact resistance from the guide 11 can be changed according to the compression ratio.

A guide roller 10c (corresponding to a contact portion with the guide 11) of the push arm 10 is provided at the end of the push arm 10.
This facilitates the introduction of the push arm 10 into the guide 11.

Further, the push arm 10 is a rod-shaped member, and the pivot portion 10a is provided at the opposite end of the guide roller 10c and is pivotally supported by the crank arm 52.
Therefore, the push arm 10 can be configured by a simple rod-shaped member, and the mechanism for regulating the small connecting rod 9 can be configured lightweight and compact.

Further, the guide 11 has a groove portion 11d (corresponding to the first guide surface) for guiding the push arm 10 before reaching the top dead center of the crank arm 52. Further, the guide 11 has a guide surface 11e (corresponding to a second guide surface) that guides the push arm 10 before the top dead center of the crank arm 52. Then, a driving force is generated in the crank arm 52 by the reaction force received by the push arm 10 from the guide surface 11e.
Therefore, the force received by the small connecting rod 9 in the combustion process can be converted into the driving force of the crank arm 52, and the efficiency of the internal combustion engine is improved. Further, the driving force can be efficiently applied to the crank arm 52 in the region where the large connecting rod 6 in the vicinity of the top dead center cannot generate the driving force.

Next, the overall configuration of the internal combustion engine 1a according to the second embodiment of the present invention will be described with reference to FIGS. 7 and 8.
FIG. 7 is a partial cross-sectional front view showing the configuration of the main part of the internal combustion engine 1a according to the second embodiment of the present invention, and FIG. 8 is a partial cross-sectional view showing the configuration of the main part of the internal combustion engine 1a according to the second embodiment. It is a side view.
Like the internal combustion engine 1 of the first embodiment, the internal combustion engine 1a has a large piston 7 in the large cylinder 2 and a small piston 8 in the small cylinder 71 of the large piston 7. Further, a cylinder block 3 and a crankcase 4 mounted on the lower part of the cylinder block 3 are provided.

The large piston 7 is connected to the crankshaft 5a by a large connecting rod 6, and the large piston 7 is configured to be slidable up and down by the rotation of the crankshaft 5. In FIG. 7, the crankshaft 5 of the internal combustion engine 1a rotates in the rotation direction R.
The crankshaft 5a includes a crank journal 51, a crank arm 52d, a crank pin 53, and two counterweights 54a. The crank journal 51 serves as a rotation shaft of the crankshaft 5, and is rotatably supported by a bearing (not shown).

The crank arm 52d connects the crank journal 51 and the crank pin 53, extends in a direction orthogonal to the rotation axis of the crankshaft 5a, and connects to the crank pin 53. The base portion 6b of the large connecting rod 6 is rotatably connected to the crankpin 53, and the crank arms 52d are connected to both ends of the crankpin 53.

The crank arm 52d is provided with a through hole 55, and the through hole 55 is provided along the crank arm 52d. The through hole 55 is provided through the rotation axis center of the crankshaft 5a and is provided so as to be orthogonal to the rotation axis of the crankshaft 5a.
The rod portion 20b of the push arm 20 is slidably inserted into the through hole 55.

As shown in FIGS. 7 and 8, the configuration of the large connecting rod 6 is common to that of the first embodiment.
The small connecting rod 19 is composed of an upper portion 91, a cage 192, and two rollers 193. The upper end of the upper portion 91 is connected to the small piston 8, and the lower end of the upper portion 91 is connected to the upper portion of the cage 192. Further, the upper portion 91 is arranged between the blades 6a of the large connecting rod 6.

The configuration of the cage 192 of the small connecting rod 19 is the same as that of the first embodiment except for the shape of the bottom beam 192c.
A roller 193 is rotatably attached to the bottom beam 192c of the cage 192, respectively, inside the cage 92, and the roller 193 is in a state of engaging with the groove portion 61 of the large connecting rod 6. The rotation axis direction of the roller 193 coincides with the rotation axis direction of the crankshaft 5. Then, the lower portion of the small connecting rod 19 is held in a slidable state on the base portion 6b of the large connecting rod 6. The roller 193 is provided at the center of the bottom beam 192c in the extending direction.
Further, the cam portion 20a of the push arm 20 is also configured to be able to come into contact with the roller 193.

The push arm 20 is composed of a cam portion 20a, a rod portion 20b, and a roller 20c. The rod portion 20b is inserted into the through hole 55 of the crank arm 52d, a cam portion 20a is provided at one end, and a roller 20c is provided at the other end.
Further, the cam portion 20a and the roller 20c are larger than the opening of the through hole 55, and the push arm 20 is configured so as not to come off from the crank arm 52d.
A curved surface 20d that abuts on the roller 193 of the small connecting rod 19 is provided on the end surface of the cam portion 20a, and the curved surface 20d is an arcuate surface that is convex outward as shown in FIG.
Further, a tip portion 20e is provided on the rotation direction R side of the cam portion 20a.

A guide 30 is provided on the lower side of the crankcase 4 and on the side of the crank journal 51. The guide 30 is composed of a guide plate 31, an elevating mechanism 32, and an actuator 34.
The guide plate 31 includes a support portion 31a on which the screw rod 32a and the screw rod 32b of the elevating mechanism 32 are mounted, and a first guide surface 31b and a second guide surface 31c to which the roller 20c of the push arm 20 abuts.

The screw rod 32b of the elevating mechanism 32 is configured as a reverse screw. Further, the screw rod 32a and the screw rod 32b are arranged in parallel and in the vertical direction in the crankcase 4, and the driving force of the actuator 34 is transmitted via the gear 33, respectively. As a result, when the screw rod 32b is driven, the screw rod 32a is driven in the reverse rotation direction. By mounting the two screw rods 32a and the screw rods 32b, the guide plate 31 can be stably supported, and the position of the guide plate 31 is less likely to change even if an impact is applied.
Then, by driving the elevating mechanism 32 with the actuator 34, the guide plate 31 can be moved closer to or further from the crank journal 51 side.

As shown in FIG. 7, the guide 30 is such that when the crank arm 52d is in the top dead center position, the roller 20c of the push arm 20 comes into contact with the portion of the second guide surface 31c closest to the crank journal 51. Have been placed.
Further, as shown in FIG. 8, the guide 30 and the push arm 20 are arranged symmetrically with the crankpin 53 interposed therebetween.

The first guide surface 31b of the guide plate 31 is provided on the upper surface of the guide plate 31, and has an arc shape recessed toward the crank journal 51 so as to smoothly abut the roller 20c and not hinder the movement of the roller 20c. Is formed in. The second guide surface 31c is configured to become lower toward the end. Further, the second guide surface 31c is configured so that the inclination angle with respect to the horizontal is larger than that of the first guide surface 31b.

Next, the operation of the second embodiment will be described with reference to FIGS. 9 to 11.
FIG. 9 is a diagram showing a contact start state between the push arm 20 and the small connecting rod 19, and FIG. 10 is a diagram showing a change in the top dead center position of the small piston 8 by the guide 30 of the internal combustion engine 1a. FIG. 11 is a schematic diagram showing the behavior of the small connecting rod 19 during combustion of the internal combustion engine 1a.

When the crank arm 52d rotates upward from the bottom dead center, the push arm 20 rotates with the cam portion 20a close to the crank arm 52d, as shown in FIG.
Then, the tip portion 20e of the cam portion 20a comes into contact with the roller 193 of the small connecting rod 19. Before the roller 20c of the push arm 20 comes into contact with the guide plate 31, the small connecting rod 19 is pushed up by the tip portion 20e of the cam portion 20a.
After this, the roller 20c comes into contact with the first guide surface 31b of the guide plate 31, and the roller 20c moves along the first guide surface 31b.
By pushing up the small connecting rod 19 before the roller 20c comes into contact with the guide plate 31, the small piston 8 can be smoothly pushed up by the guide plate 31 and the load applied to the small connecting rod 19 and the push arm 20 can be reduced. ..

Further, in FIG. 9, when the roller 20c comes into contact with the first guide surface 31b of the guide plate 31, the first guide surface 31b is configured so that the roller 20c and the first guide surface 31b make an acute angle contact.
The position of the first guide surface 31b so that the angle θ at which the speed direction of the roller 20c at the contact start point between the roller 20c and the first guide surface 31b and the tangential direction of the first guide surface 31b intersect is an acute angle. And the shape is composed. As a result, the impact load due to the contact between the roller 20c and the guide plate 31 is suppressed. Further, the quietness is improved and the durability of the guide 30 and the push arm 20 is improved.

Next, when the crank arm 52d rotates while the roller 20c is in contact with the first guide surface 31b, the rod portion 20b on the roller 20c side slides toward the crank arm 52d. Then, the rod portion 20b on the cam portion 20a side protrudes from the crank arm 52d, and the roller 193 is pushed up by the cam portion 20a. The roller 193 moves upward along the groove 61 of the large connecting rod 6, and the small piston 8 is pushed up by the small connecting rod 19.

In FIG. 10, H and L indicate an internal combustion engine 1a in a high compression ratio state and a low compression ratio state, respectively. The height at the top dead center of the small piston 8 can be changed by the guide 30, and is changed by the height of the guide plate 31 with which the roller 20c abuts.
In FIG. 10, the guide plate 31 is held in a high position as shown in the state H. As a result, the cam portion 20a side of the push arm 20 protrudes from the crank arm 52d, and the small connecting rod 19 is pushed up. As a result, the small piston 8 is restricted in a state of being moved to a high position, and the volume formed by the large cylinder 2, the large piston 7, the small cylinder 71 and the small piston 8 is reduced. Then, the volume of the combustion chamber in the internal combustion engine 1a becomes small, and the compression ratio becomes high.

Further, as shown in the state L in FIG. 10, when the guide plate 31 is held at a low position, the amount of protrusion is smaller than that of the crank arm 52d of the push arm 20, and the small piston 8 is at a lower position at the top dead center. In the state L, the roller 193 of the small connecting rod 19 is in contact with the lower end of the groove portion 61 of the large connecting rod 6, and the small piston 8 is in the lowest position at the top dead center. Then, in this state L, the compression ratio of the combustion chamber in the internal combustion engine 1a becomes the lowest.

In this way, the trajectory of the cam portion 20a of the push arm 20 can be adjusted, the top dead center position of the small piston 8 can be changed, and the compression ratio can be changed by the holding position of the guide plate 31. The ascending speed per rotation angle of the crank arm 52d can be adjusted by adjusting the shape of the first guide surface of the guide plate 31.

Next, the action at the time of combustion will be described.
In the compression stroke, the roller 20c is in contact with the first guide surface 31b, and in the combustion step, the roller 20c is in contact with the second guide surface 31d.
As shown in FIG. 11, in the combustion process of the internal combustion engine 1a, the roller 20c comes into contact with the second guide surface 31c from the first guide surface 31b of the guide plate 31.
When the small piston 8 is pushed down by combustion, the small connecting rod 19 pushes down the push arm 20. As a result, the roller 20c is pressed against the second guide surface 31c. As a result, the roller 20c moves downward along the second guide surface 31c and moves in the rotation direction R direction. The push arm 20 is driven in the rotation direction R by the reaction force received by the roller 20c from the second guide surface 31c. Then, the driving force received by the push arm 20 is transmitted to the crank arm 52d, and the crank arm 52d is driven in the rotation direction R.
As a result, the movement of the small piston 8 is converted into the rotation of the crank arm 52d.

As described above, according to the second embodiment of the present invention, the internal combustion engine 1a is slidably arranged in the large cylinder 2, and has a large piston 7 having a small cylinder 71 and a large piston 7. A large connecting rod 6 for connecting the crank pin 53 of the crankshaft 5a is provided. Further, the internal combustion engine 1a includes a small piston 8 slidably arranged in the small cylinder 71, and a small connecting rod 9 for connecting the small piston 8 and the large connecting rod 6. The internal combustion engine 1a is provided on the crank arm 52d of the crankshaft 5, and has a push arm 20 (corresponding to an abutting body) that abuts on the small connecting rod 9 and changes the position of the small connecting rod 9 with respect to the large connecting rod 6. Be prepared. Further, the internal combustion engine 1a includes a guide 30 that guides the movement locus of the push arm 20.
Therefore, the height position of the small connecting rod 9 by the push arm 20 can be set by the guide plate 31. The height position of the small connecting rod 9 can be adjusted with a simple configuration. Further, since the push arm 20 is provided on the crank arm 52, it becomes easy to move the small piston 8 in synchronization with the large piston 7. As a result, in the internal combustion engine 1 having the large piston 7 and the small piston 8 in one cylinder 2, the compression ratio can be changed and the thermal efficiency can be improved.

Further, the guide 30 comes into contact with a part of the movement locus of the push arm 20.
Therefore, the contact resistance between the push arm 20 and the guide 30 can be reduced, and the work efficiency of the internal combustion engine 1a can be improved. In addition, noise due to contact can be reduced, and the durability of the configuration for changing the compression ratio can be improved.

Further, the contact start position between the push arm 20 and the guide 30 can be changed.
Therefore, the height position of the small connecting rod 19 can be changed by a simple configuration. Further, the timing at which the push arm 20 receives the contact resistance from the guide 30 can be changed according to the compression ratio.
Therefore, at the time of low compression where the inertial force applied to the crankshaft 5a becomes small, the contact timing is delayed, and the loss of the inertial force due to the contact resistance can be reduced.

A roller 20c of the push arm 20 (corresponding to a contact portion with the guide 30) is provided at the end of the push arm 20.
This makes it easier to bring the push arm 20 into contact with the guide 30.

The push arm 20 includes a cam portion 20a (corresponding to the first contact portion) that abuts on the small connecting rod 19, a roller 20c (corresponding to the second contact portion) that abuts on the guide 30, and a cam portion 20a. A rod portion 20b for connecting to the roller 20c is provided. The rod portion 20b is supported by penetrating the crank arm 52d, and is slidable in the crank arm 52d within a certain range.
Therefore, since the push arm 20 is supported by using the crank arm 52d, the push arm 20 can be supported with a simple structure, and the increase in weight due to the support structure of the push arm 20 can be reduced.

Further, the guide 30 has a first guide surface 31b (corresponding to the first guide surface) that guides the push arm 20 before reaching the top dead center of the crank arm 52d. Further, the guide 30 has a second guide surface 31c (corresponding to a second guide surface) that guides the push arm 20 before the top dead center of the crank arm 52d. Then, a driving force is generated in the crank arm 52d by the reaction force received by the push arm 20 from the second guide surface 31c.
Therefore, the force received by the small connecting rod 9 in the combustion process can be converted into the driving force of the crank arm 52d, and the efficiency of the internal combustion engine is improved. Further, the driving force can be efficiently applied to the crank arm 52d in the region where the large connecting rod 6 in the vicinity of the top dead center cannot generate the driving force.

The above embodiment is merely an embodiment of the present invention, and can be arbitrarily modified and applied without departing from the spirit of the present invention.

1 Internal combustion engine 2 Crankshaft 3 Crankshaft 4 Crankcase 5 Crankshaft 5a Crankshaft 6 Conrod 6a Blade 6b Base 7 Piston 7a Piston pin 8 Piston 9 Conrod 10 Push arm 10a Pivot branch 10b Tip 10c Guide roller 10d Guide 11a Rod 11b Rail part 11c Actuator 11d Groove part 11e Guide surface 51 Crank journal 52 Crank arm 52a First regulation surface 52b Second regulation surface 52d Crank arm 53 Crank pin 54 Counter weight

Claims (7)

A large piston that is slidably arranged in a large cylinder and has a small cylinder,
A large connecting rod that connects the large piston and the crankpin of the crankshaft,
A small piston slidably arranged in the small cylinder,
A small connecting rod that connects the small piston and the large connecting rod,
An abutting body provided on the crank arm of the crankshaft, which abuts on the small connecting rod and changes the position of the small connecting rod with respect to the large connecting rod.
An internal combustion engine including a guide for guiding a moving locus of the abutting body. The internal combustion engine according to claim 1, wherein the guide abuts on a part of the movement locus of the abutting body. The internal combustion engine according to claim 2, wherein the contact start position between the contact body and the guide can be changed. The internal combustion engine according to any one of claims 1 to 3, wherein the contact portion of the contact body with the guide is provided at an end portion of the contact body. The contact body is a rod-shaped member and is a rod-shaped member.
The internal combustion engine according to claim 4, wherein the end portion of the contact body opposite to the contact portion with the guide is pivotally supported by the crank arm. The contact body includes a first contact portion that contacts the small connecting rod, a second contact portion that contacts the guide, the first contact portion, and the second contact portion. Equipped with a rod part to connect
The internal combustion engine according to any one of claims 1 to 4, wherein the rod portion is supported by penetrating the crank arm and is slidable in the crank arm within a certain range. The guide
A first guide surface that guides the abutting body before reaching the top dead center of the crank arm, and
It has a second guide surface that guides the abutting body after the top dead center of the crank arm.
The internal combustion engine according to any one of claims 1 to 6, wherein a driving force is generated in the crank arm by a reaction force received by the abutting body from the second guide surface.

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