JP2023151468A - Variable compression ratio device of internal combustion engine - Google Patents

Abstract

To provide a variable compression ratio device of an internal combustion engine that eliminates the need for a plurality of position adjustment mechanisms in a thrust direction of a control shaft, facilitates assembly work with a simple structure, and downsizes the entire internal combustion engine.SOLUTION: A variable compression ratio device of an internal combustion engine for changing a compression ratio of an internal combustion engine 10 comprises a crankshaft 20, and bearings 51, 52 that support the crankshaft 20 or a control shaft 40, where a flange part 40d is provided on an outer peripheral surface of the control shaft 40 so as to protrude in a radial direction, and an elastic member 80 is arranged between the flange part 40d and the bearing 51. The variable compression ratio device of the internal combustion engine eliminates the need for a plurality of position adjustment mechanisms in a thrust direction of the control shaft, facilitates assembly work with a simple structure, and downsizes the entire internal combustion engine.SELECTED DRAWING: Figure 4

Description

The present invention relates to a variable compression ratio device for an internal combustion engine that changes the compression ratio of the internal combustion engine.

Conventionally, as a compression ratio variable device for an internal combustion engine, in order to change the compression ratio of the internal combustion engine, an eccentric cam is inserted between the large end of the connecting rod and the crank pin, and the eccentric cam is rotated with respect to the crank pin. There are some that change the compression ratio.
In this compression ratio variable device, a control shaft that rotates an eccentric cam is inserted concentrically into the crankshaft, and the control shaft is rotated by a predetermined angle according to a command from the control device, and the eccentric cam is rotated to adjust the compression ratio. (See Patent Document 1).

Special table 2015-508470 publication

In a variable compression ratio internal combustion engine as described in Patent Document 1, the control shaft extends concentrically within the crankshaft and is rotatable about the crankshaft. Therefore, when assembling the variable compression ratio device, multiple clearance adjustment mechanisms are required in the thrust direction of the control shaft, which complicates the structure, requires time and effort for assembly, and increases the size of the entire internal combustion engine. There are issues such as:

The present invention has been made in view of the above-mentioned circumstances, and has a single clearance adjustment mechanism in the thrust direction of the control shaft, which simplifies the structure and facilitates assembly work. It is an object of the present invention to provide a variable compression ratio device for an internal combustion engine that can be downsized as a whole.

In the present invention, an eccentric cam is inserted between a large end of a connecting rod and a crank pin in order to change the compression ratio of an internal combustion engine, and the compression ratio is changed by rotating the eccentric cam with respect to the crank pin. In a compression ratio variable device for an internal combustion engine,
a crankshaft that transmits rotational force from the connecting rod;
a control shaft inserted into the crankshaft and rotating the eccentric cam;
a bearing rotatably supporting the crankshaft or the control shaft,
A radially protruding collar is provided on the outer peripheral surface of the control shaft,
It is characterized in that an elastic member is disposed between the collar portion and one of the bearings.

According to the above configuration, it is not necessary to provide a plurality of position adjustment mechanisms in the thrust direction of the control shaft, and the compression ratio variable device for the internal combustion engine is provided, which facilitates the assembly work and allows the overall size of the internal combustion engine to be downsized. can be provided.

Furthermore, the present invention is characterized in that the outer diameter of the elastic member is smaller than the outer diameter of a bearing with which the elastic member comes into contact.

According to the above configuration, since the elastic member is disposed so as to be housed between the bearing and the flange portion, assembly becomes easy and enlargement around the control shaft can be suppressed.

Further, the present invention includes an eccentric cam inserted between a large end of a connecting rod and a crank pin in order to change the compression ratio of an internal combustion engine, and by rotating the eccentric cam with respect to the crank pin. In the compression ratio variable device of the internal combustion engine to be changed,
a crankshaft that transmits rotational force from the connecting rod;
a control shaft inserted into the crankshaft and rotating the eccentric cam;
a first bearing that rotatably rotates the crankshaft;
a second bearing rotatably supporting the control shaft;
An elastic member is arranged between the first bearing and the second bearing.

According to the above configuration, since it is not necessary to provide multiple position adjustment mechanisms in the thrust direction of the control shaft, it is possible to create a structure that is easy to assemble with high precision, and also allows internal combustion to be adjusted in the axial direction of the crankshaft and the control shaft. Control the expansion of institutions.

Furthermore, the present invention provides a method for changing the compression ratio of an internal combustion engine by inserting an eccentric cam between a large end of a connecting rod and a crank pin, and rotating the eccentric cam with respect to the crank pin. In a compression ratio variable device for an internal combustion engine that changes the
a crankshaft that transmits rotational force from the connecting rod;
a control shaft inserted into the crankshaft and rotating the eccentric cam;
a second bearing rotatably supporting the control shaft;
The support member that supports the second bearing has a wall portion formed on the side opposite to the crank pin in the axial direction of the crankshaft, into which the control shaft is inserted;
An elastic member is arranged between the second bearing and the wall.

According to the above configuration, it is not necessary to provide multiple position adjustment mechanisms for the control shaft in the thrust direction, and the structure becomes simple, making assembly work easier and making it possible to downsize the entire internal combustion engine. .

According to the present invention, it is possible to provide a variable compression ratio device for an internal combustion engine.

1 is a diagram showing the internal structure of a power unit equipped with a variable compression ratio device according to an embodiment of the present invention. FIG. 3 is a diagram showing a crank pin and an eccentric cam together with the surrounding structure. 3 is an enlarged view of a part of FIG. 2. FIG. FIG. 3 is an enlarged view of the vicinity of the positioning member. 5 is a view taken along the line VV in FIG. 4. FIG. It is a perspective view of a bearing holder. FIG. 3 is a sectional view of a main part of a variable compression ratio device for an internal combustion engine according to a second embodiment, taken along the crank axis. FIG. 6 is a cross-sectional view of a main part of a variable compression ratio device for an internal combustion engine according to a third embodiment, taken along the crank axis.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In addition, in the description, directions such as front, rear, left, right, and top and bottom are the same as directions with respect to the vehicle body unless otherwise specified. Further, the symbol FR shown in each figure indicates the front of the vehicle body, and the symbol LH indicates the left side of the vehicle body.

FIG. 1 is a diagram showing the internal structure of a power unit P equipped with a variable compression ratio device 30 according to an embodiment of the present invention. This power unit P is a power unit mounted on a motorcycle and includes an internal combustion engine 10. This power unit P is not limited to a motorcycle, but may be a power unit mounted on various saddle type vehicles including three-wheeled and four-wheeled types.

The internal combustion engine 10 includes a crankcase 11 that rotatably supports a crankshaft 20 via a crankshaft bearing 15 and a first bearing 51 in a positioning member 50 (described later), a crank web 21 on the crankshaft 20, and a crank case 11. It includes a cylinder portion 12 that slidably accommodates a piston (not shown) connected in this order through a pin 22 and a connecting rod (hereinafter referred to as connecting rod) 23. A primary gear 26 is supported on the crankshaft 20. The primary gear 26 meshes with a driven gear (not shown).
FIG. 1 shows a case where the internal combustion engine 10 is a horizontal engine in which a cylinder portion 12 projects horizontally from a crankcase 11 toward the front. In FIG. 1, the symbol C1 indicates a crank axis passing through the axis of the crankshaft 20 supported by the crankcase 11. Reference numeral C2 indicates a crank pin axis passing through the axis of the crank pin 22. The crank axis C1 and the crank pin axis C2 are parallel.

The compression ratio variable device 30 is a device that varies the compression ratio by making the central axis of the large end 23a of the connecting rod 23 eccentric with respect to the position of the crank pin axis C2 so that the position of the top dead center of the piston changes. It is. This compression ratio variable device 30 includes an eccentric cam 31 that rotates to change the position of the central axis of the large end 23a of the connecting rod 23, a motor 32 that serves as a power source, and a link between the motor 32 and the eccentric cam 31. A power transmission mechanism 33 is provided. The rotation angle of the motor 32 is controlled by a control unit 100 mounted on the motorcycle. This control unit 37 acquires the rotational position of a part of the power transmission mechanism 33 (in this configuration, the rotational position of the control shaft 40) via the potentiometer 101, and moves the motor 32 to a target position based on the acquired rotational position. Control rotation. The control unit 100 is, for example, an ECU (Electronic Control Unit) provided in a motorcycle.

Next, the eccentric cam 31, the power transmission mechanism 33, and the peripheral configuration thereof will be explained.
FIG. 2 is a diagram showing the crank pin 22 and the eccentric cam 31 together with the surrounding structure, and is a view taken along the line II--II in FIG. 1. The eccentric cam 31 is a component disposed between the large end 23a of the connecting rod 23 and the crank pin 22, and is a component that gradually changes the cam thickness along the circumferential direction. When the eccentric cam 31 is at the reference position (top dead center), the central axis of the large end 23a of the connecting rod 23 coincides with the crank pin axis C2. When the power of the motor 32 is transmitted to the power transmission mechanism 33 and the eccentric cam 31 rotates in the circumferential direction, the cam thickness of the eccentric cam 31 gradually changes in the circumferential direction. The central axis is gradually displaced (for example, to an eccentric position C3) and no longer coincides with the crankpin axis C2. Therefore, when the eccentric cam 31 is rotated to the eccentric position C3, the distance between the central axis of the large end 23a of the connecting rod 23 and the crank axis C1 changes, the stroke amount of the piston changes, and the compression ratio changes. .

A gear portion 31a is integrally provided on the outer peripheral portion of the eccentric cam 31.
The power transmission mechanism 33 includes an intermediate gear 35 that meshes with the gear portion 31a of the eccentric cam 31, a shaft 40 (hereinafter referred to as the control shaft 40) having at its tip a gear portion 40b that meshes with the intermediate gear 35; It includes a drive side gear section 41 provided at the base end. The gear portion 40b is formed integrally with the shaft portion 40a, but may be formed separately. The control shaft 40 has a flange portion 40d that bulges in the radial direction.

FIG. 3 is an enlarged view of a part of FIG.
As shown in FIGS. 2 and 3, the intermediate gear 35 is rotatably supported by the crank web 21. The intermediate gear 35 is configured as a two-stage gear including a large diameter gear 35a that meshes with the gear portion 31a of the eccentric cam 31, and a small diameter gear 35b that meshes with the gear portion 40b of the control shaft 40. In the figure, reference numeral 36 denotes a component that is fastened to the crank web 21 with the intermediate gear 35 interposed therebetween by a fastening member 36t. This component 36 functions as a drop-off prevention component that prevents the intermediate gear 35 from falling off.

As shown in FIG. 1, the control shaft 40 passes through the crankshaft 20 and is disposed coaxially with the crankshaft 20, and includes a control shaft bearing 46 and a second bearing 52 disposed within a positioning member 50, which will be described later. It is rotatably supported through. This control shaft 40 passes through a cover 48 disposed on the right side of the crankshaft 20 and extends to the vicinity of the motor 32.

The drive side gear section 41 has a worm gear 41a keyed to the base end 40c of the control shaft 40, and the worm gear 41a decelerates the rotation of a worm wheel provided on the motor 32 and transmits the decelerated rotation to the control shaft 40. do. Note that the configuration of the drive side gear section 41 is not limited to the configuration using the worm gear 41a, and any known speed reduction mechanism can be adopted as appropriate. Further, although the case where the motor 32 is the power source is illustrated, the power source may be other than the motor 32.

As shown in FIG. 1, the right end sides of the crankshaft 20 and the control shaft 40 are supported and positioned by a positioning member 50 held by the cover 48. FIG. 4 is an enlarged view of the vicinity of the positioning member 50. The positioning member 50 includes a first bearing 51 that supports the crankshaft 20, a second bearing 52 that supports the control shaft 40, a shim 56, a bearing holder 57 as a bearing holder that holds these, and an elastic member. Equipped with spring 80.

The arrangement of various members around the positioning member 50 will be described below. For convenience, the side where power is input from the motor 32 to the control shaft 40 is the right side in the crankshaft direction, and the control shaft 40 supplies power to the intermediate gear 35. The output side is the left side. That is, the description will be made assuming that the right side in FIG. 1 is the right side and the left side is the left side.

As shown in FIG. 4, the positioning member 50 is fitted into the hole 48a of the cover 48 and held. The hole 48a of the cover 48 has a large diameter part 48b that holds the bearing holder 57, and a small diameter part 48c on the right side of which the control shaft 40 is inserted. A stepped portion forms a wall portion 48d between the large diameter portion 48b and the small diameter portion 48c.

As shown in FIG. 6, the bearing holder 57 fitted into the large diameter portion 48b includes a cylindrical peripheral wall portion 57a and a donut-shaped side wall portion 57b on the left side of the peripheral wall portion 57a. 5 is a perspective view of a bearing holder 57. FIG. The bearing holder 57 has oil delivery holes 57c provided at intervals in the circumferential direction of the peripheral wall portion 57a. Further, a portion of the peripheral wall 57a of the bearing holder 57 has a window 57d.

As shown in FIG. 4, the side wall portion 57b presses the left surface of the first bearing 51 to suppress movement to the left. The right side of the first bearing 51 is fixed to the crankshaft 20 by a first fixing portion 53, and the first bearing 51 is positioned with respect to the crankshaft 20. Furthermore, a groove 57e is formed in the inner peripheral surface of the bearing holder 57 in the circumferential direction. Further to the right of the control shaft 40, a threaded portion 40f is formed. When the fixing member 54 is fitted into the groove 57e, the second bearing 52 is prevented from moving to the right via the shim 55, and the lock nut 58 screwed into the threaded portion 40f also prevents the second bearing 52 from moving to the right. Movement in that direction is restricted.

The control shaft 40 is formed with a collar portion 40d that protrudes outward from its circumferential surface. The flange portion 40d is provided at a position where it comes into contact with the left surface of the second bearing 52, and the tip of the flange portion 40d extends to the vicinity of the inner circumferential surface of the bearing holder 57.

A spring 80 as an elastic member is disposed in a compressed state between the right side surface of the first bearing 51 and the left side surface of the flange portion 40d of the control shaft 40. Referring also to FIG. 5, the outer diameter of the spring 80 is smaller than the outer diameter of the first bearing 51, the second bearing 52, and the collar portion 40d, and is composed of the first bearing 51 and the collar portion 40d. It is housed in a small space and has a compact configuration. The spring 80 between the first bearing 51 and the flange portion 40d suppresses rattling between the control shaft 40, the first bearing 51, and the second bearing 52.

Since the compression ratio variable device for an internal combustion engine according to the embodiment of the present invention is configured as described above, it has the following effects.

In order to change the compression ratio of the internal combustion engine 10, an eccentric cam 31 is inserted between the large end 23a of the connecting rod 23 and the crank pin 22, and the compression ratio is changed by rotating the eccentric cam 31 with respect to the crank pin 22. A variable compression ratio device for an internal combustion engine includes a crankshaft 20 that transmits rotational force from a connecting rod 23, a control shaft 40 that is inserted into the crankshaft 20 and rotates an eccentric cam 31, and a crankshaft 20 or a control shaft. The control shaft 40 has a first bearing 51 and a second bearing 52 that rotatably support the control shaft 40, and a radially projecting collar 40d is provided on the outer peripheral surface of the control shaft 40. A spring 80 is arranged between one bearing 51.

According to the above configuration, it is not necessary to provide a plurality of position adjustment mechanisms for the control shaft 40 in the thrust direction, resulting in a simple structure, facilitating assembly work, and downsizing the internal combustion engine 10 as a whole. I can do it.

Further, in the present invention, since the outer diameter of the spring 80 is smaller than the outer diameter of the first bearing 51 with which the spring 80 comes into contact, the spring 80 is arranged so as to be housed between the first bearing 51 and the collar portion 52d. This makes assembly easier and prevents the area around the control shaft 40 from becoming enlarged.

In addition, in order to change the compression ratio of the internal combustion engine 10, an eccentric cam 31 is inserted between the large end 23a of the connecting rod 23 and the crank pin 22, and the compression ratio is changed by rotating the eccentric cam 31 with respect to the crank pin 22. A variable compression ratio device for an internal combustion engine that changes the compression ratio of an internal combustion engine includes a crankshaft 20 that transmits rotational force from a connecting rod 23, a control shaft 40 inserted into the crankshaft 20 that rotates an eccentric cam 31, and a control shaft 40 that rotates an eccentric cam 31. A first bearing 51 that rotatably rotates and a second bearing 52 that rotatably supports the control shaft 40 are provided, and a spring 80 is provided between the first bearing 51 and the second bearing 52. will be placed.

According to the above configuration, it is not necessary to provide a plurality of position adjustment mechanisms in the thrust direction of the control shaft 40, so it is possible to have a structure that is easy to assemble with high accuracy, and the axes of the crankshaft 20 and the control shaft 40 can be easily assembled. This suppresses the enlargement of the internal combustion engine 10 in the direction.

Furthermore, in order to change the compression ratio of the internal combustion engine 10, an eccentric cam 31 is inserted between the large end 23a of the connecting rod 23 and the crank pin 22, and by rotating the eccentric cam 31 with respect to the crank pin 22, the compression ratio is changed. A variable compression ratio device for an internal combustion engine that changes the ratio includes a crankshaft 20 that transmits rotational force from a connecting rod 23, a control shaft 40 that is inserted into the crankshaft 20 and rotates an eccentric cam 31, and a control shaft 40 that is inserted into the crankshaft 20 and rotates an eccentric cam 31. A control shaft 40 is inserted into the support member that supports the second bearing 52 on the opposite side of the crank pin 31 in the axial direction of the crankshaft 20. A wall portion 48d is formed, and a spring 90 is disposed between the second bearing 52 and the wall portion 48d.

According to the above configuration, it is not necessary to provide a plurality of position adjustment mechanisms for the control shaft 40 in the thrust direction, resulting in a simple structure, facilitating assembly work, and downsizing the internal combustion engine 10 as a whole. I can do it.

In the first embodiment, the spring 80 is disposed between the first bearing 51 and the collar 40d, but as in the second embodiment shown in FIG. In the shaft 40, a spring 80 may be disposed so as to contact the first bearing 51 and the second bearing 52, respectively.

Furthermore, as in the third embodiment shown in FIG. 8, a spacer 93 is disposed between the first bearing 51 and the second bearing 52, and is provided so as to be slidable in the axial direction. A spring 90 as an elastic member is arranged in a compressed state between a first spring holding member 91 that abuts on the right side and a second spring holding member 92 that abuts on the left side of the wall 48d of the hole 48a of the cover 48. You may.

In the embodiments described above, the springs 80 and 90 were used as the elastic members, but instead of the springs, various other elastic members such as disc springs may be used.

Although the variable compression ratio device 30 for an internal combustion engine according to one embodiment of the present invention has been described above, aspects of the present invention are not limited to the above-described embodiment, and can be implemented in various ways within the scope of the gist of the present invention. This includes those implemented in various embodiments.

P...Power unit,
10...Internal combustion engine,
20...Crankshaft, 22...Crank pin, 23...Conrod, 23a...Big end,
31...Eccentric cam
40...Control shaft, 40d...Brim part, 48...Cover, 48d...Wall part
51...first bearing, 52...second bearing,
80...Spring (elastic member),
90...Spring (elastic member).

Claims (4)

In order to change the compression ratio of the internal combustion engine (10), an eccentric cam (31) is inserted between the large end (23a) of the connecting rod (23) and the crank pin (22). A variable compression ratio device for an internal combustion engine that changes the compression ratio by rotating the eccentric cam (31),
a crankshaft (20) that transmits rotational force from the connecting rod (23);
a control shaft (40) inserted into the crankshaft (20) and rotating the eccentric cam (31);
bearings (51, 52) rotatably supporting the crankshaft (20) or the control shaft (40);
A radially projecting collar portion (40d) is provided on the outer peripheral surface of the control shaft (40),
A variable compression ratio device for an internal combustion engine, characterized in that an elastic member (80) is disposed between the flange (40d) and one of the bearings (51). The variable compression ratio device for an internal combustion engine according to claim 1, wherein the outer diameter of the elastic member (80) is smaller than the outer diameter of a bearing (51) with which the elastic member (80) comes into contact. In order to change the compression ratio of the internal combustion engine (10), an eccentric cam (31) is inserted between the large end (23a) of the connecting rod (23) and the crank pin (22). A variable compression ratio device for an internal combustion engine that changes the compression ratio by rotating the eccentric cam (31),
a crankshaft (20) that transmits rotational force from the connecting rod (23);
a control shaft (40) inserted into the crankshaft (20) and rotating the eccentric cam (31);
a first bearing (51) that rotatably rotates the crankshaft (20);
a second bearing (52) rotatably supporting the control shaft (40);
A variable compression ratio device for an internal combustion engine, characterized in that an elastic member (80) is disposed between the first bearing (51) and the second bearing (52). In order to change the compression ratio of the internal combustion engine (10), an eccentric cam (31) is inserted between the large end (23a) of the connecting rod (23) and the crank pin (22). A variable compression ratio device for an internal combustion engine that changes the compression ratio by rotating the eccentric cam (31),
a crankshaft (20) that transmits rotational force from the connecting rod (23);
a control shaft (40) inserted into the crankshaft (20) and rotating the eccentric cam (31);
a second bearing (52) rotatably supporting the control shaft (40);
The support member (48) that supports the second bearing (52) includes a wall portion, through which the control shaft (40) is inserted, on the opposite side of the crank pin (31) in the axial direction of the crankshaft (20). (48d) is formed,
A variable compression ratio device for an internal combustion engine, characterized in that an elastic member (90) is disposed between the second bearing (82) and the wall portion (70a).

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