JP6597652B2 - Internal combustion engine balance device - Google Patents

Description

  The present invention relates to a balance device for an internal combustion engine, and more particularly to a balance device suitable for mounting on a single cylinder or four-cycle two-cylinder internal combustion engine.

  A reciprocating internal combustion engine is generally equipped with a balance device. During operation of the internal combustion engine, an inertial force due to the movement of the piston is generated. The balance device is configured to generate an excitation force for canceling vibration caused by the inertial force. If the balance device appropriately cancels vibrations, an internal combustion engine with excellent quietness can be realized.

  Patent Document 1 discloses a balance device for mounting on a four-cylinder internal combustion engine. This balance device has a balance shaft to which an eccentric weight is attached. The balance shaft is connected to the crankshaft through an inconstant speed gear. When the crankshaft rotates during operation of the internal combustion engine, the balance shaft rotates via the inconstant speed gear.

  At this time, the eccentric weight attached to the balance shaft periodically generates an excitation force according to the angular velocity and angular acceleration of the balance shaft. The angular velocity and angular acceleration of the balance shaft change with a profile corresponding to the characteristics of the inconstant speed gear. In Patent Document 1, the inconstant speed gear is formed such that a large excitation force is generated at a crank angle at which the vibration to be canceled is large. For this reason, according to the conventional balance device, it is possible to effectively suppress the vibration of the internal combustion engine and realize excellent quietness.

JP 2010-169045 A

  However, in the balance device described in Patent Document 1, it is necessary to transmit the rotation of the crankshaft to the balance shaft by a gear. For this reason, in an internal combustion engine in which the distance between them is increased, the gear must be enlarged. As a result, the balance device becomes large, and a situation in which the reduction in size and weight of the internal combustion engine is hindered occurs.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a balance device that can effectively cancel the vibration of the internal combustion engine without hindering the reduction in size and weight of the internal combustion engine. To do.

In order to achieve the above object, a first invention is a balance device for an internal combustion engine,
A crankshaft rotating about the CS main shaft as a rotation axis;
A balance shaft that rotates using a BS support shaft parallel to the CS main shaft as a rotation shaft,
The crankshaft includes a CS eccentric weight that decenters the center of gravity of the crankshaft from the center of the CS main shaft,
The balance shaft includes a BS eccentric weight that decenters the center of gravity of the balance shaft from the center of the BS support shaft, and
A connecting rod for connecting a CS connecting point provided at a position off the center of the CS main shaft of the crankshaft and a BS connecting point provided at a position off the center of the BS support shaft of the balance shaft; ,
A CS coupling mechanism that enables relative rotation of the crankshaft and the coupling rod with the CS coupling point as a rotation center;
A BS connection mechanism that enables relative rotation between the balance shaft and the connection rod with the BS connection point as a rotation center;
A guide portion for guiding the movement of the connecting rod so that the balance shaft rotates in reverse with the crankshaft;
It is characterized by providing.

The second invention is the first invention, wherein
A connection point adjustment mechanism that enables displacement of at least one of the CS connection point and the BS connection point in the direction of the respective rotation radius;
A sliding portion provided at one point of the connecting rod,
The guide part restricts the movement of the sliding part to a linear motion from the CS main shaft side toward the BS support shaft side and a linear motion in the opposite direction.

The third invention is the first invention, wherein
A connection point adjustment mechanism that enables displacement of at least one of the CS connection point and the BS connection point in the direction of the respective rotation radius;
The guide portion can rotate in the same plane as the movable plane of the connecting rod around a position overlapping with the connecting rod, and can slide the connecting rod in the direction of the center line of the connecting rod. It is characterized by holding.

Moreover, 4th invention is set in 1st invention,
A restriction portion provided at a midpoint between the CS connection point and the BS connection point of the connection rod;
The distance between the CS connection point and the BS connection point is equal to the distance between the CS main shaft and the BS support shaft,
The distance between the center of the CS main shaft and the CS connection point is equal to the distance between the center of the BS support shaft and the BS connection point;
The guide portion includes a BS side guide that prevents the restricting portion from being displaced in the same rotational direction as the CS connection point at a position where the restricting portion is closest to the BS support shaft, and the restricting portion is the CS A CS-side guide that prevents the restricting portion from being displaced in the same rotational direction as the CS connection point at a position closest to the main shaft.

The fifth invention is the second invention, wherein
The crankshaft is used in an offset crank method in which the center of the CS main shaft is installed at a position offset from the axis of reciprocating motion of the piston by a certain value.
The balance shaft and the guide portion are arranged so that at least one of the center of the CS main shaft and the center of the BS support shaft is formed at a position offset by a certain value from the axis of the linear motion. Features.

The sixth invention is the fifth invention, wherein
A CS-BS center line connecting the center of the CS main axis and the center of the BS support shaft is offset from the axis of the linear motion by a predetermined value.

The seventh invention is the fifth invention, wherein
The center of the CS main axis is located on the axis of the linear motion, and the center of the BS support shaft is offset from the axis of the linear motion by a certain value.

The eighth invention is the fifth invention, wherein
The center of the BS support shaft is located on the axis of the linear motion, and the center of the CS main shaft is offset from the axis of the linear motion by a certain value.

The ninth invention is the fifth invention, wherein
The center of the BS support shaft is offset from the linear motion axis to one side by a certain value, and the center of the CS main shaft is offset from the linear motion axis to the other side by a certain value. It is characterized by that.

The tenth invention is the third invention, wherein
The crankshaft is used in an offset crank method in which the center of the CS main shaft is installed at a position offset from the axis of reciprocating motion of the piston by a certain value.
The rotation center of the guide portion is offset by a certain value from a CS-BS center line connecting the center of the CS main shaft and the center of the BS support shaft.

Further, an eleventh aspect of the invention is any one of the first to tenth aspects of the invention,
The CS connection point is provided on the same side as the center of gravity of the CS eccentric weight with respect to the center of the CS main shaft, and the BS connection point is a center of gravity of the BS eccentric weight with respect to the center of the BS support shaft. It is provided on the same side.

In addition, a twelfth aspect of the invention is any one of the first to tenth aspects of the invention,
The CS connection point is provided on the opposite side to the center of gravity of the CS eccentric weight with respect to the center of the CS main shaft, and the BS connection point is a center of gravity of the BS eccentric weight with respect to the center of the BS support shaft. It is provided on the opposite side.

The thirteenth aspect of the invention is any one of the first to twelfth aspects of the invention.
The balance shaft is provided with a moment applying mechanism that gives a rotational moment opposite to the rotational direction of the crankshaft.

The fourteenth invention is the thirteenth invention, in which
The moment application mechanism includes a cam mounted on the balance shaft, and a spring member that reduces by being pressed by the cam.
The cam presses the spring member in the process in which the connecting rod moves toward the BS support shaft as the balance shaft rotates, and the cam shaft is positioned at a position where the axis of the connecting rod overlaps the BS support shaft. It is formed to receive the reverse rotational moment from the spring member.

According to a fifteenth aspect, in any one of the first to fourteenth aspects,
It is mounted on a single-cylinder or 4-cycle 2-cylinder internal combustion engine.

According to a sixteenth aspect of the invention, in any one of the first to fifteenth aspects,
The connecting rod is disposed so as to be inclined from the axis of reciprocation of the piston at the top dead center and the bottom dead center of the internal combustion engine,
The CS eccentric weight is located in a region opposite to the CS connection point with a CS axis parallel to the axis of reciprocation of the piston passing through the center of rotation of the CS main shaft under the condition of the top dead center. Has a center of gravity,
The BS eccentric weight is a region on the opposite side of the BS connection point across the BS axis parallel to the axis of reciprocating motion of the piston through the rotation center of the BS support shaft under the condition of the top dead center Has a center of gravity.

The seventeenth invention is the sixteenth invention, in which
The CS eccentric weight is large enough to cancel the combined force of the excitation force caused by the connecting rod of the internal combustion engine, a part of the excitation force caused by the piston of the internal combustion engine, and a part of the excitation force caused by the connecting rod. Has a weight and center of gravity,
The BS eccentric weight has a weight and a center of gravity large enough to cancel the remainder of the excitation force caused by the piston of the internal combustion engine and the remainder of the excitation force caused by the connecting rod,
The part and the remaining part are equal.

The eighteenth invention is the seventeenth invention, wherein
The balance shaft is connected to the connecting rod at one end thereof,
Of the weight of the BS eccentric weight, the weight for canceling the remainder of the excitation force caused by the connecting rod is largely reflected in the vicinity of the one end compared to the vicinity of the other end of the balance shaft. It is characterized by being.

The nineteenth aspect of the invention is any one of the first to eighteenth aspects of the invention,
The connecting rod has a CS side bearing on the crankshaft side,
The CS coupling mechanism has a CS side eccentric shaft rotatably held by the CS side bearing,
The CS-side eccentric shaft is fixed to the CS main shaft such that a CS eccentric point shifted from the center by a predetermined value coincides with the center of the CS main shaft,
The center of the CS-side eccentric shaft constitutes the CS connection point.

Further, a twentieth aspect of the invention is any one of the first to nineteenth aspects of the invention,
The connecting rod has a BS side bearing on the balance shaft side,
The BS coupling mechanism has a BS side eccentric shaft rotatably held by the BS side bearing,
The BS side eccentric shaft is fixed to the BS support shaft such that a BS eccentric point shifted from the center by a certain value coincides with the center of the BS support shaft,
The center of the BS side eccentric shaft constitutes the BS connection point.

According to the first invention, the crankshaft and the balance shaft rotate in reverse to each other. While they rotate together, the center of gravity of the crankshaft and the center of gravity of the balance shaft are in phase twice. Hereinafter, a direction connecting two points having the same phase is referred to as a “Y direction”, and a direction perpendicular thereto is referred to as “X direction”. In the process of reverse rotation of the crankshaft and the balance shaft, the X component of the excitation force caused by the CS eccentric weight (hereinafter referred to as “CS excitation force”) and the excitation force caused by the BS eccentric weight (hereinafter referred to as “CS eccentric weight”) The X components of “BS excitation force” act so as to cancel each other, while the Y components are combined and strengthened with each other. In an internal combustion engine, as the piston reciprocates, an inertial force that causes vibration is generated in the reciprocating direction.According to the present invention, the Y direction is the reciprocating direction. The inertial force of the piston can be canceled out by the combined force of the CS excitation force and the BS excitation force.
In the present invention, the CS eccentric weight rotates together with the crankshaft. For this reason, the Y component of the CS excitation force changes in a sine wave shape as the crank angle changes. On the other hand, the BS eccentric weight is rotated reversely to the crankshaft through the connecting rod. In this case, the rotation of the BS eccentric weight inevitably becomes an inconstant speed rotation if the rotation of the crankshaft is a constant speed rotation. The Y component of the BS excitation force shows a sine wave-like change distorted with respect to the change in the crank angle.
If the ratio of the connecting rod length lc to the crank radius rc, that is, the linkage ratio lc / rc is infinite, the inertial force resulting from the reciprocating motion of the piston shows a sinusoidal change with respect to the rotation of the crankshaft. At a practical linkage ratio lc / rc, the inertial force shows a sine wave-like change distorted with respect to the change in the crank angle. According to the present invention, since the Y component of the BS excitation force changes to a distorted sine wave shape, the combined force of the CS excitation force and the BS excitation force is accurate with the inertial force resulting from the reciprocating motion of the piston. Can be matched. For this reason, according to this invention, the vibration of an internal combustion engine can be suppressed effectively.
And this invention can implement | achieve said effect with a connecting rod and a guide part, without using a gearwheel. The connecting rod and the guide portion can be formed so as to be lighter and smaller than a gear. Therefore, according to the present invention, it is possible to effectively cancel the vibration of the internal combustion engine without hindering the reduction in size and weight of the internal combustion engine.

According to the second invention, the position of the sliding portion on the connecting rod is limited to any point on the linear motion allowed by the guide portion. Hereinafter, the direction of this straight line will be referred to as the “y direction”, and the direction perpendicular thereto will be referred to as the “x direction”. When the crankshaft rotates, the CS connection point changes the position in the x direction together with the position in the y direction. And since the x coordinate of the sliding part is regulated, if the CS connection point moves in the x positive direction, the BS connection point inevitably moves in the x negative direction. If the displacement direction of the CS connection point changes from the x positive direction to the x negative direction, the displacement direction of the BS connection point changes from the x negative direction to the x positive direction. At this time, the BS connection point is always displaced in the same direction as the CS connection point in the y direction. As a result, the balance shaft rotates in the opposite direction with respect to the crankshaft.

  Also in the third invention, the CS connection point and the BS connection point are displaced in the same direction in the y direction, while being displaced in the opposite direction in the x direction, as in the second invention. For this reason, according to the present invention, the balance shaft accompanying the rotation of the crankshaft can be reversely rotated with respect to the crankshaft. In the present invention, the ratio BS / CS between the distance from the BS connection point to the guide portion (BS distance) and the distance from the CS connection point to the guide portion (CS distance) varies with the rotation of the crankshaft. . In the second invention, this ratio is always constant. Due to the lever principle, the larger the ratio, the greater the change in the rotation angle of the balance shaft that accompanies the change in the crank angle. For this reason, according to this invention, the profile different from the case of 2nd invention can be given to the excitation force for canceling the inertial force of a piston.

  According to the fourth invention, the restriction part of the connecting rod is closest to the BS support shaft in a situation where the center of the CS main shaft, the CS connection point, the restriction part, the center of the BS support shaft and the BS connection point are aligned. To do. Hereinafter, this position is referred to as a “first thought point”. At the first thought point, the axial force of the connecting rod acting on the BS connecting point does not become a rotational moment. For this reason, if there is no restriction | limiting in a moving direction, BS connection point can be rotated to any direction from a 1st thought point with the change of a crank angle. If the BS connection point is displaced in the same direction as the rotation direction of the crankshaft, the balance shaft rotates in the same direction as the crankshaft. In the present invention, displacement in that direction is prevented by the restricting portion of the connecting rod and the BS side guide. For this reason, if the crank angle changes from the above situation, the BS connection point is displaced in the direction opposite to the rotation direction of the crankshaft. When the first thought point is deviated, the axial force of the connecting rod acting on the BS connecting point generates a rotational moment. For this reason, the balance shaft continues to rotate in reverse with the rotation of the crankshaft. When the crankshaft is rotated 180 ° from the state of the first thought point, the center of the CS main shaft, the CS connection point, the control portion, the center of the BS support shaft, and the BS connection with the restriction portion of the connecting rod closest to the CS main shaft A situation is formed in which the dots are aligned. Hereinafter, this position is referred to as a “second thought point”. At the second thought point, the displacement of the restricting portion is restricted by the CS side guide. As a result, the BS connection point is also led in the direction opposite to the rotation direction of the crankshaft at the second thought point. By repeating the above operation, the balance shaft can continue to rotate reversely with respect to the crankshaft via the connecting rod according to the present invention.

  According to any of the fifth to ninth inventions, since the crankshaft is used in the offset crank method, the inertial force resulting from the movement of the piston from the top dead center toward the bottom dead center, and the bottom dead center. The inertial force resulting from the movement of the piston from the top to the top dead center becomes non-target. When the sliding part of the connecting part reciprocates on a line segment connecting the center of the CS main shaft and the center of the BS support shaft (hereinafter referred to as “CS-BS center line”), the balance shaft is The target angular velocity profile is shown in the process from the dead center to the bottom dead center and vice versa. In this case, the excitation force generated by the BS eccentric weight becomes a target in the forward path and the return path. On the other hand, in this invention, the linear motion of a sliding part is guided on the straight line which does not correspond with CS-BS centerline. In this case, distortion occurs in the angular velocity profile of the balance axis, and the excitation force generated by the BS eccentric weight is asymmetric between the forward path and the backward path. Therefore, according to the present invention, it is possible to generate a vibration force that is asymmetric between the forward path and the return path, and to appropriately cancel the inertial force generated by the piston under the condition of the offset crank.

  According to the tenth invention, as in the case of the ninth invention, the inertial force generated by the piston is asymmetric between the forward path and the return path. In the configuration in which the rotatable guide portion holds the connecting rod, when the rotation center is set on the CS-BS center line, the angular velocity profile of the balance axis is the target in the forward path and the return path, and as a result, the BS eccentric weight is The excitation force to be generated is also subject to the forward and return journeys. On the other hand, if the rotation center of the guide part deviates from the CS-BS center line, the excitation force generated by the BS eccentric weight becomes asymmetric between the forward path and the return path. For this reason, according to the present invention, it is possible to appropriately cancel the inertial force generated by the piston under the condition of the offset crank.

  According to the eleventh aspect of the present invention, it is possible to generate an excitation force that changes in a desired profile in the Y direction after substantially aligning the rotational phase of the CS eccentric weight and the rotational phase of the BS eccentric weight.

According to the twelfth aspect of the invention, the rotational force of the CS eccentric weight and the rotational phase of the BS eccentric weight are substantially aligned, and the excitation force that changes in a profile different from the profile realized in the eleventh aspect is applied in the Y direction. Can be generated.

In the thirteenth invention, a rotational moment is applied to the balance shaft through a connecting rod. In this configuration, the axial force of the connecting rod does not give any rotational moment to the balance shaft at a position where the axis of the connecting rod overlaps the rotation center of the balance shaft (hereinafter referred to as “think point”). For this reason, when the external force applied to the balance shaft is only the axial force of the connecting rod, the balance shaft can be rotated in either the forward or reverse direction at the thought point. In the present invention, a moment of reverse rotation is applied to the balance shaft by the moment applying mechanism. For this reason, according to the present invention, the balance shaft can be continuously rotated in the direction opposite to the rotation direction of the crankshaft.

  According to the fourteenth invention, an appropriate rotational moment can be given to the balance shaft at the thought point by the cam and the spring member.

  According to the fifteenth aspect of the invention, the internal combustion engine includes one piston that operates alone or two pistons that operate in the same phase. In these internal combustion engines, the pistons do not cancel out the inertial force of the reciprocating motion. According to the present invention, vibrations of these internal combustion engines can be appropriately suppressed by the excitation force generated by the balance device.

  According to the sixteenth invention, under the condition of top dead center, the piston and the connecting rod generate an exciting force in a direction along the axis of reciprocating motion of the piston (hereinafter referred to as “reference direction”). At this time, the connecting rod applies an exciting force to the CS eccentric weight in a direction from the center of the CS main axis to the CS connecting point (hereinafter referred to as “first inclination direction”), and approximately the center of the BS support shaft. An excitation force in a direction from the first to the BS connection point (hereinafter referred to as “second inclination direction”) is applied to the BS eccentric weight. The combined force of these excitation forces has a component toward the first tilt direction and the second tilt direction in addition to the component toward the reference direction. In the present invention, the center of gravity of the CS eccentric weight is provided on the opposite side of the CS connection point across the CS axis. According to this center of gravity, in addition to the excitation force component in the reference direction, the excitation force component in the first tilt direction can be canceled out. In the present invention, the center of gravity of the BS eccentric weight is provided on the opposite side of the BS connection point across the BS axis. According to this center of gravity, in addition to the excitation force component in the reference direction, the excitation force component in the second tilt direction can be canceled. At the bottom dead center of the internal combustion engine, the excitation force is canceled by the same principle. For this reason, according to this invention, the exciting force which each of a piston, a connecting rod, and a connecting rod can cancel | amend appropriately.

  According to the seventeenth aspect, at the top dead center and the bottom dead center of the internal combustion engine, the excitation force caused by the CS eccentric weight and the BS eccentric weight is balanced with the excitation force caused by the connecting rod, the piston and the connecting rod. be able to. In addition, under the situation excluding top dead center and bottom dead center, the excitation force caused by the connecting rod and the BS eccentric weight can be balanced with the excitation force caused by the CS eccentric weight. For this reason, according to this invention, the excitation force resulting from each element can always be canceled out favorably.

  According to the eighteenth aspect, the excitation force resulting from the connecting rod is input to one end of the balance shaft. And the BS eccentric weight with which a balance axis | shaft is provided can cancel the excitation force with the weight largely reflected in the vicinity of the one end. The further the moment the force is applied to the balance shaft, the greater is the distance between the place where the excitation force is input and the place where the weight for canceling the vibration force is placed. According to the present invention, it is possible to cancel the excitation force to each element while suppressing the moment sufficiently small.

  According to the nineteenth aspect, the connecting rod and the CS main shaft can be connected by the CS side eccentric shaft. According to this structure, the crankshaft and the connecting rod can be rotated relatively with the center of the CS side bearing of the connecting rod as the center of rotation. That is, the “CS connection point” in the first invention can be formed at the center of the CS-side bearing. Further, according to the CS side eccentric shaft, the center of the CS main shaft can be decentered by a certain value from the center of the CS side bearing, that is, the CS connection point. Thus, according to the present invention, a “CS connection mechanism” that satisfies the functions required by the first invention can be specifically realized.

  According to the twentieth invention, the connecting rod and the BS support shaft can be connected by the BS side eccentric shaft. According to this structure, the balance shaft and the connecting rod can rotate relatively with the center of the BS side bearing of the connecting rod as the center of rotation. That is, the “BS connection point” in the first invention can be formed at the center of the BS side bearing. Further, according to the BS side eccentric shaft, the center of the BS support shaft can be eccentric by a certain value from the center of the BS side bearing, that is, the BS connection point. Thus, according to the present invention, the “BS coupling mechanism” that satisfies the functions required by the first invention can be specifically realized.

It is a figure which shows the structure of Embodiment 1 of this invention. It is a figure for demonstrating the relationship between the state of the balance apparatus shown in FIG. 1, and crank angle (theta). It is a figure which shows the relationship between crank angle (theta) and balance axis | shaft rotation angle (BS rotation angle) (alpha) in the balance apparatus shown in FIG. It is a figure which shows the relationship between crank angle (theta) and BS angular velocity d (alpha) / d (theta) in the balance apparatus shown in FIG. It is a figure which shows the relationship between crank angle (theta) and BS angular acceleration d2 (alpha) / d (theta) 2 in the balance apparatus shown in FIG. FIG. 2 is a diagram for explaining a relationship between an operation of a piston of the internal combustion engine shown in FIG. 1 and a crank angle θ. It is a figure which shows the profile of the exciting force which the inertial force which the piston of an internal combustion engine emits, and the balance apparatus shown in FIG. It is the figure which compounded and represented the exciting force of the balance shaft shown in FIG. 7, and the exciting force of a crankshaft. It is the figure which synthesize | combined and represented the synthetic | combination excitation force and piston inertia force which were shown in FIG. It is a figure for demonstrating the relationship between the state of the modification of the balance apparatus of Embodiment 1 of this invention, and crank angle (theta). It is a figure which shows the profile of the inertial force which the piston of an internal combustion engine emits, and the exciting force which the balance apparatus shown in FIG. 10 emits. It is the figure which compounded and represented the exciting force of the balance axis | shaft shown in FIG. 11, and the exciting force of a crankshaft. It is the figure which compounded and represented the synthetic | combination excitation force shown in FIG. 12, and the inertial force of a piston. It is a figure for demonstrating the relationship between the state of the balance apparatus in Embodiment 2 of this invention, and crank angle (theta). It is a figure for demonstrating the relationship between the state of the balance apparatus in Embodiment 3 of this invention, and crank angle (theta). It is a figure which shows the locus | trajectory of the movement which arises in the pivot of a connecting rod in connection with operation | movement of the balance apparatus shown in FIG. In the balance apparatus shown in FIG. 15, it is a figure for demonstrating the conditions which a guide part should satisfy | fill. It is a figure which shows the essential structure with which the balance apparatus shown in FIG. 15 is provided as a guide part. It is a figure for demonstrating the structure of Embodiment 4 of this invention. It is a figure for demonstrating operation | movement of the balance apparatus shown in FIG. It is a figure which shows the change of the torque which a spring mechanism gives to a balance axis | shaft in each state shown in FIG. It is a figure which shows the change of the torque which a spring mechanism gives to a balance axis | shaft in the modification of Embodiment 4 of this invention. It is a figure for demonstrating the structure of the 2nd modification of Embodiment 4 of this invention. It is a figure for demonstrating operation | movement of the 3rd modification of Embodiment 4 of this invention. It is a figure for demonstrating the structure of Embodiment 5 of this invention. It is a figure for demonstrating operation | movement of the balance apparatus shown in FIG. The spring mechanism in each state shown in FIG. 26 is a graph showing changes in torque applied to the balance shaft. It is a figure for demonstrating the structure of Embodiment 6 of this invention. It is a figure for demonstrating the effect which the structure of the offset crank with which the internal combustion engine shown in FIG. 28 is provided. It is a figure which shows the relationship between the displacement of the piston and crank angle (theta) in the internal combustion engine shown in FIG. FIG. 31A is a diagram for explaining the configuration of the balance device according to the sixth embodiment of the present invention. FIG. 31 (B) is a diagram for explaining a configuration of a first modification of the balance device according to the sixth embodiment of the present invention. FIG. 31 (C) is a diagram for explaining a configuration of a second modification of the balance device according to the sixth embodiment of the present invention. FIG. 31 (D) is a diagram for explaining a configuration of a third modification of the balance device according to the sixth embodiment of the present invention. FIG. 32 is a diagram showing the relationship between the crank angle θ and the BS angular velocity dα / dθ in the configuration shown in FIG. 31A using the offset ratio h / r as a parameter. FIG. 32 is a diagram showing a profile of an inertial force generated by a piston of an internal combustion engine and a composite excitation force generated by the balance device shown in FIG. It is the figure which synthesize | combined and represented the synthetic | combination excitation force and piston inertia force which were shown in FIG. It is a figure for demonstrating the structure of the balance apparatus in Embodiment 7 of this invention. FIG. 36 is a diagram showing the relationship between the crank angle θ and the BS angular velocity dα / dθ in the configuration shown in FIG. 35, using the offset ratio h / r as a parameter. It is a figure which shows the profile of the inertial force which the piston of an internal combustion engine emits, and the synthetic | combination excitation force which the balance apparatus shown in FIG. 35 emits. It is the figure which synthesize | combined and represented the synthetic | combination excitation force shown in FIG. 37, and the inertial force of a piston. It is a figure for demonstrating the structure of Embodiment 8 of this invention. It is a figure for demonstrating the principle in which the balance apparatus shown in FIG. 39 cancels an excitation force. It is a figure for demonstrating the gravity center position of CS eccentric weight with which the balance apparatus shown in FIG. 39 is provided. It is a perspective view for demonstrating the characteristic of the crankshaft with which the balance apparatus shown in FIG. 39 is provided. It is a perspective view for demonstrating the characteristic of the balance axis | shaft with which the balance apparatus shown in FIG. 39 is provided. It is a figure for demonstrating operation | movement of the balance apparatus shown in FIG. It is a perspective view for demonstrating the characteristic of the other example of the balance axis | shaft which can be used in Embodiment 8 of this invention. It is a figure for demonstrating the structure of Embodiment 9 of this invention. It is a figure for demonstrating the principle in which the balance apparatus shown in FIG. 46 cancels an exciting force. It is a figure for demonstrating the gravity center position of CS eccentric weight with which the balance apparatus shown in FIG. 46 is provided. It is a perspective view for demonstrating the characteristic of the balance axis | shaft with which the balance apparatus shown in FIG. 46 is provided. It is a figure for demonstrating operation | movement of the balance apparatus shown in FIG. It is a perspective view for demonstrating the characteristic of the other example of the balance axis | shaft which can be used in Embodiment 9 of this invention. It is a disassembled perspective view of the balance apparatus of Embodiment 10 of this invention. It is a disassembled perspective view of the connecting rod shown in FIG. It is sectional drawing which represented the principal part of the balance apparatus of Embodiment 10 of this invention by the side view. FIG. 53 is a diagram for explaining a method of performing co-hole machining on the CS-side eccentric shaft and the BS-side eccentric shaft shown in FIG. 52. It is a figure for demonstrating operation | movement of the balance apparatus of Embodiment 10 of this invention. It is a figure for demonstrating the 1st modification of the balance apparatus of Embodiment 10 of this invention. It is sectional drawing for demonstrating the structure of the BS side eccentric shaft with which the 2nd modification of the balance apparatus of Embodiment 10 of this invention is provided. It is sectional drawing for demonstrating the structure of the CS side eccentric shaft with which the 3rd modification of the balance apparatus of Embodiment 10 of this invention is provided. It is sectional drawing for demonstrating the structure and operation | movement of the 4th modification of the balance apparatus of Embodiment 10 of this invention. It is a disassembled perspective view of the balance apparatus of Embodiment 11 of this invention. FIG. 62 is an exploded perspective view of the connecting rod shown in FIG. 61. It is sectional drawing which represented the principal part of the balance apparatus of Embodiment 11 of this invention by the side view. It is a figure showing a mode that the amount of eccentricity which arises in BS side eccentric shaft in Embodiment 11 of this invention changes. It is a figure for demonstrating operation | movement of the balance apparatus of Embodiment 11 of this invention. It is sectional drawing for demonstrating the structure and operation | movement of the modification of the balance apparatus of Embodiment 11 of this invention.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
FIG. 1 is a diagram for explaining the configuration of the first embodiment of the present invention. The present embodiment includes an internal combustion engine 10. The internal combustion engine 10 has a piston 12. In the present embodiment, the internal combustion engine 10 is a single-cylinder four-cycle engine having only one piston 12.

  The piston 12 is connected to the crankshaft 16 via a connecting rod 14. The crankshaft 16 includes a crankpin 18 connected to the connecting rod 14. The crankpin 18 is integrally formed with a crank journal (hereinafter referred to as “CS main shaft”) 22 via a crank arm 20. The CS main shaft 22 is rotatably held by a bearing provided in the cylinder block.

  The crankshaft 16 includes a CS eccentric weight 24. The CS eccentric weight 24 is provided such that its center of gravity is located on the substantially opposite side of the crank pin 18 with the center of the CS main shaft 22 interposed therebetween. The CS eccentric weight 24 is given a weight (mc) for canceling the weight of the connecting rod 14 and a weight for canceling a weight (mp / 2) corresponding to half of the weight of the piston 12.

  The crankshaft 16 rotates once while the piston 12 reciprocates once between the top dead center and the bottom dead center. Hereinafter, the direction of the reciprocating motion of the piston 12 is referred to as “Y direction”, and the direction perpendicular thereto is referred to as “X direction”.

In the present embodiment, the CS eccentric weight 24 is set so that a phase difference of approximately 180 ° crank angle (° CA) occurs between the CS eccentric weight 24 and the piston 12. That is, the phase of the CS eccentric weight 24 is set so that the following two conditions are satisfied.
(1) When the piston 12 is located at the top dead center, the center of gravity of the CS eccentric weight 24 is substantially located at the bottom dead center side displacement end in the Y direction.
(2) When the piston 12 is positioned at the bottom dead center, the center of gravity of the CS eccentric weight 24 is approximately positioned at the top dead center side displacement end in the Y direction.

  The internal combustion engine 10 includes a balance device 30. The crankshaft 16 is a component of the balance device 30. The crankshaft 16 is provided with a CS connection point 32 at a position off the center of the CS main shaft 22. More specifically, the CS connection point 32 is provided on the opposite side of the CS eccentric weight 24 across the center of the CS main shaft 22.

  A connecting rod 36 is connected to the CS connecting point 32 via a CS connecting mechanism 34. The connecting rod 36 is rotatably held by the CS connecting mechanism 34. For this reason, the crankshaft 16 and the connecting rod 36 can relatively rotate in a plane parallel to the rotating surface of the crankshaft 16 with the CS connecting point 32 as the rotation center.

  The other end of the connecting rod 36 is connected to the balance shaft 40 at the BS connecting point 38. The balance shaft 40 includes a BS connection mechanism 42 at the BS connection point 38. The connecting rod 36 is rotatably held by the BS connecting mechanism 42. For this reason, the connection rod 36 and the balance shaft 40 can rotate relatively with the BS connection point 38 as the rotation center.

  The balance shaft 40 includes a BS support shaft 44 at a position away from the BS connection point 38. The BS support shaft 44 is provided in parallel with the CS main shaft 22 and is rotatably held by a bearing provided in the cylinder block. For this reason, the balance shaft 40 can rotate in a plane parallel to the rotation surface of the crankshaft 16 with the BS support shaft 44 as a rotation axis.

  The balance shaft 40 is also provided with a BS connection point adjustment mechanism 46 that holds the BS connection mechanism 42. The BS connection point adjusting mechanism 46 is a mechanism for passively adjusting the position of the BS connection mechanism 42 on the balance shaft 40, that is, the position of the BS connection point 38 to the correct position. With the function of the BS connection point adjusting mechanism 46, the BS connection point 38 can be displaced within a certain range in the direction of the rotation radius of the balance shaft 40 passing through the center of the BS support shaft 44.

  The balance shaft 40 is further provided with a BS eccentric weight 48. The BS eccentric weight 48 is provided such that its center of gravity is located on the opposite side of the BS connection point 38 across the center of the BS support shaft 44. The BS eccentric weight 48 is given a weight for canceling out a weight (mp / 2) which is approximately half of the weight of the piston 12.

In the present embodiment, the balance shaft 40 rotates once in the direction opposite to the rotation direction when the crankshaft 16 rotates once. Here, as shown in FIG. 1, the BS eccentric weight 48 is provided so as to be in phase with the CS eccentric weight 24. That is, the phase of the BS eccentric weight 48 is shifted by approximately 180 ° CA from the phase of the piston 12, similarly to the phase of the CS eccentric weight 24. For this reason, the following two conditions are also established between the phase of the BS eccentric weight 48 and the phase of the piston 12.
(1) When the piston 12 is positioned at the top dead center, the center of gravity of the BS eccentric weight 48 is approximately positioned at the bottom dead center side displacement end in the Y direction.
(2) When the piston 12 is located at the bottom dead center, the center of gravity of the BS eccentric weight 48 is located approximately at the top dead center side displacement end in the Y direction.

  The connecting rod 36 has a pivot 50 at its midpoint. A circular sliding portion 52 is attached to the pivot 50. The cylinder block is provided with a guide portion 54 that regulates the movement of the sliding portion 52. The guide portion 54 has a sliding space whose longitudinal direction is the CS-BS center line 56 that connects the center of the CS main shaft 22 and the center of the BS support shaft 44. The sliding part 52 can move along the inner wall of the sliding space. As a result, the movement of the pivot 50 is limited to linear movement on the CS-BS centerline 56.

[Description of Basic Operation of Balance Device of Embodiment 1]
FIG. 2 is a diagram for explaining the operation of the balance device 30 shown in FIG. In FIG. 2, the horizontal axis indicates the crank angle θ [° CA]. Hereinafter, regarding the crank angle θ, 0 [° CA] or 360 [° CA] corresponds to the top dead center, and 180 [° CA] corresponds to the bottom dead center. Further, the direction of the CS-BS center line 56 is defined as “y direction”, and the direction perpendicular thereto is defined as “x” direction. However, in FIG. 2, for convenience of explanation, the y direction coincides with the Y direction (movement direction of the piston 12).

  In FIG. 2, in the state of θ = 0 [° CA], the rotation angle α of the balance shaft 40 (hereinafter referred to as “BS rotation angle α”) is also 0 [deg]. At this time, the center of gravity of the CS eccentric weight 24 and the center of gravity of the BS eccentric weight 48 are both located at the bottom dead center side displacement end.

  In FIG. 2, it is assumed that the crankshaft 16 rotates in the clockwise direction. When the crankshaft 16 rotates from the state of θ = 0 [° CA], the CS connection point is displaced in the (x positive direction, y negative direction). At this time, the x coordinate of the pivot 50 is always maintained at the origin by the guide portion 54. For this reason, the BS connection point 38 is displaced in the (x negative direction, y negative direction). As a result, the balance shaft 40 rotates in the direction opposite to the rotation direction of the crankshaft 16.

  The CS connection point 32 continues to be displaced in the (x positive direction, y negative direction) until θ reaches 90 [° CA]. At this time, if the x coordinate of the BS connection point 38 changes by the same distance as the x coordinate of the CS connection point 32, that is, if the connection rod 36 remains vertical in FIG. The y coordinate is displaced by a distance equivalent to the y coordinate of the CS connection point 32. However, in the balance device 30, the CS connection point 32 and the BS connection point 38 move away in the x direction until θ reaches 90 [° CA]. In order to compensate for the distance in the x direction, the y coordinate of the BS connection point 38 must be displaced larger than the y coordinate of the CS connection point 32. As a result, when the crankshaft 16 rotates 90 [° CA], the BS rotation angle α exceeds 90 [deg].

  Until the crank angle θ exceeds 90 [° CA] and reaches 180 [° CA], the CS connection point 32 changes (x negative direction, y negative direction). At this time, the BS connection point 38 is displaced in the (x positive direction, y negative direction). Here, as the crank angle θ increases, the CS connection point 32 and the BS connection point 38 approach each other in the x direction. For this reason, the change of the y coordinate of the BS connection point 38 is smaller than the change of the y coordinate of the CS connection point 32. When the crank angle θ reaches 180 [° CA], the BS rotation angle α similarly reaches 180 [deg].

For the above reason, the balance shaft 40 rotates at a faster speed than the crankshaft 16 in the process of changing the crank angle θ from 0 [° CA] to 90 [° CA]. The rotational speed of the balance shaft 40 is lower than the rotational speed of the crankshaft 16 in the process in which the crank angle θ changes from 90 [° CA] to 180 [° CA]. Such a speed change also occurs when the crank angle θ is changed from 180 [° CA] to 360 [° CA] by the same mechanism.

As described above, the balance device 30 in the present embodiment has the following characteristics.
(1) The crankshaft 16 and the balance shaft 40 rotate in the reverse direction at the same cycle.
(2) When the crankshaft 16 rotates at a constant speed, the balance shaft 40 rotates at a nonuniform speed. At this time, the rotational speed of the balance shaft 40 is such that when the crank angle θ is in the range of 0 [° CA] to 90 [° CA] and in the range of 270 [° CA] to 360 [° CA]. It becomes faster than the rotation speed. When the crank angle θ is in the range of 90 [° CA] to 270 [° CA], the rotational speed of the balance shaft 40 is lower than the rotational speed of the crank shaft 16.
(3) In a state where the crank angle θ = 0 [° CA], that is, a state where the piston 12 is located at the top dead center, the center of gravity of the crankshaft 16 and the center of gravity of the balance shaft 40 are both at the displacement end on the bottom dead center side. To position. In the state where the crank angle θ = 180 [° CA], that is, the piston 12 is located at the bottom dead center, the center of gravity of the crankshaft 16 and the center of gravity of the balance shaft 40 are both positioned at the top dead center side displacement end. To do.

During operation of the internal combustion engine 10, reciprocating motion occurs in the piston 12, and rotational motion occurs in the crankshaft 16 and the balance shaft 40. At this time, the connecting rod 14 undergoes a combined motion of reciprocating motion and rotational motion. The main weight of the connecting rod 14 is present in the portion rotating with the crankpin 18. For this reason, (mc) of the weight (mc + mp / 2) of the crankshaft 16 cancels out with the rotating portion of the connecting rod 14. Therefore, during the operation of the internal combustion engine 10, it can be considered that the following movement occurs in the inside.
(1) Reciprocation of weight (mp) in the Y direction accompanying the movement of the piston 12 (2) Forward rotation of the eccentric weight (mp / 2) accompanying the rotation of the crankshaft 16 (3) Eccentricity accompanying the rotation of the balance shaft 40 Reverse motion of weight (mp / 2)

  The Y direction reciprocating motion of weight (mp) generates an inertia force in the Y direction. This inertial force changes its magnitude in synchronization with the operation of the piston 12 and has a generally negative maximum value at the top dead center and a generally positive maximum value at the bottom dead center.

  The forward rotation motion of the eccentric weight (mp / 2) and the reverse motion of the eccentric weight (mp / 2) generate an excitation force outward of the respective rotation radii. Of these excitation forces, the X components cancel each other and the Y components are synthesized. The synthesized excitation force Y component cancels out the inertial force accompanying the operation of the piston 12. For this reason, according to the balance device 30 in the present embodiment, vibration during the operation of the internal combustion engine 10 can be suppressed sufficiently small.

[Detailed Description of Operation of Balance Device of Embodiment 1]
FIG. 3 shows a relationship established between the crank angle θ and the BS rotation angle α in the present embodiment. FIG. 3 shows a state in which the above-mentioned non-uniform rotation occurs on the balance shaft 40 as the crankshaft 16 rotates.

  FIG. 4 is a diagram in which the BS rotation angle α shown in FIG. 3 is replaced with a BS angular velocity dα / dθ. If the balance shaft 40 rotates in reverse with the crankshaft 16 at a constant speed, the BS angular velocity dα / dθ is always -1. On the other hand, in the present embodiment, due to the unequal speed rotation of the balance shaft 40, the BS angular velocity dα / dθ has a large absolute value near the top dead center. Further, near the bottom dead center, the BS angular velocity dα / dθ has a small absolute value.

  FIG. 5 is a diagram in which the BS angular velocity dα / dθ shown in FIG. 4 is further replaced with BS angular acceleration d2α / dθ2. If the rotation speed of the balance shaft 40 is constant with the crankshaft 16, the BS angular acceleration d2α / dθ2 is always zero. On the other hand, in the present embodiment, due to the non-uniform rotation of the balance shaft 40, the BS angular acceleration d2α / dθ2 has a large absolute value near the middle between the top dead center and the bottom dead center.

  A centrifugal force proportional to the square of the angular velocity acts on the balance shaft 40. If angular acceleration is generated on the balance shaft 40, the reaction force acts on the balance shaft 40. And the balance axis | shaft 40 generate | occur | produces the excitation force according to the synthetic value of the centrifugal force and reaction force mentioned above. For this reason, in this embodiment, the excitation force generated by the balance shaft 40 is distorted with respect to the excitation force generated by the crankshaft 16.

  FIG. 6 is a diagram for explaining the movement of the piston 12 with respect to the change in the crank angle θ. In the internal combustion engine 10, the piston 12 is connected to the CS main shaft 22 via a crankshaft 16 and a connecting rod 14. Here, the connecting rod length is lc, and the crank radius is rc. Further, the ratio of both, that is, the linkage ratio is represented by lc / rc.

  As shown in FIG. 6, in the process of changing the crank angle θ from 0 [° CA] to 90 [° CA], the coordinates of the crank pin 18 are displaced in the (X positive direction, Y negative direction). Since the X coordinate of the piston 12 is constant, the crank pin 18 moves away from the piston 12 in the X direction in this process. In order to compensate for the distance in the X direction, the Y coordinate of the piston 12 must be largely displaced as compared with the Y coordinate of the crankpin 18. Therefore, the stroke PS90 generated in the piston 12 when the crank angle θ changes from 0 [° CA] to 90 [° CA] is larger than the displacement amount in the Y direction generated in the crankpin 18 during that time.

  In the process of changing the crank angle θ from 90 [° CA] to 180 [° CA], the coordinates of the crank pin 18 are displaced in the (X negative direction, Y negative direction). In this process, the crankpin 18 approaches the piston 12 in the X direction. Since both approach in the X direction, the displacement amount of the piston 12 in the Y direction is smaller than the displacement amount of the crank pin 18 in the Y direction. For this reason, the piston displacement amount (PS180-PS90) when the crank angle θ changes from 90 [° CA] to 180 [° CA] is smaller than the above-described PS90. A similar change in displacement occurs when the piston 12 is displaced from the bottom dead center side to the top dead center side. For the above reasons, when the crankshaft 16 rotates at a constant speed, the displacement speed of the piston 12 is relatively high near the top dead center, while it is relatively low near the bottom dead center.

FIG. 7 shows a profile of the inertial force generated by the piston 12 and the excitation force generated by the balance device 30. Waveforms 60, 62 and 64 are respectively the following force profiles.
Waveform 60: Y component of excitation force generated by eccentric weight (mp / 2) of crankshaft 16 Waveform 62: Y component of excitation force generated by eccentric weight (mp / 2) of balance shaft 40 Waveform 64: Piston 12 Inertial force

The crankshaft 16 rotates eccentric weight (mp / 2) at a constant speed. For this reason, the waveform 60 corresponding to the excitation force of the crankshaft 16 is a sine wave having almost no distortion.
The balance shaft 40 rotates the eccentric weight (mp / 2) at a constant speed in the process from the top dead center to the middle point, and slowly in the process from the middle point to the bottom dead center. For this reason, the waveform 62 corresponding to the balance axis 40 has a distorted sine wave shape having tension in the vicinity of 90 [° CA] and in the vicinity of 270 [° CA].

  The piston 12 generates an inertial force corresponding to the displacement speed. The displacement speed of the piston 12 is high near the top dead center as described above, and is low near the bottom dead center. Therefore, the waveform 64 corresponding to the piston 12 has a peak at 0 [° CA] or 360 [° CA] on the top dead center side, but has a peak near 180 [° CA] on the bottom dead center side. It has a distorted sine wave shape that does not have.

FIG. 8 is a diagram showing the excitation force obtained by synthesizing the excitation force Y component generated by the crankshaft 16 and the excitation force Y component generated by the balance shaft 40 in comparison with the inertial force of the piston 12. The three types of waveforms shown in FIG. 8 are as follows.
Waveform 60 × 2: equivalent to twice the excitation force of the waveform 60 shown in FIG. 7 Waveform 60 + 62: equivalent to the synthesis of the waveform 60 and the waveform 62 shown in FIG. 7 Waveform 64: the same as the waveform 64 shown in FIG.

  In the present embodiment, the rotation of the crankshaft 16 is transmitted to the balance shaft 40 via the connecting rod 36. On the other hand, the rotation of the crankshaft 16 can be transmitted to the balance shaft 40 using, for example, a normal perfect circular gear mechanism. In this case, the balance shaft 40 rotates at the same speed as the crankshaft 16, and the excitation force Y component of the balance shaft 40 follows a sine wave having no distortion as in the waveform 60. Therefore, in this case, the resultant force of the excitation force Y component generated by both the crankshaft 16 and the balance shaft 40 is obtained by doubling the excitation force of the waveform 60, that is, the waveform 60 × shown in FIG. This is equivalent to 2.

  The waveform 60 does not include distortion. For this reason, even if the waveform 60 is combined with the waveform 60, the combined waveform 60 × 2 is not so close to the inertia force waveform 64 of the piston 12. On the other hand, the waveform 60 + 62 generated by combining the waveform 62 with the waveform 60 is relatively flat near the bottom dead center and has a peak rise near the top dead center. This waveform 60 + 62 is much closer to the target shape of the waveform 64 than the waveform 60 × 2.

FIG. 9 shows a waveform generated by further combining the waveform 64 with the waveform 60 × 2 and the waveform 60 + 62 shown in FIG. The meaning of each waveform is as follows.
Waveform 60 × 2 + 64: Unbalance force remaining in the internal combustion engine 10 when the balance shaft 40 is operated by a gear mechanism Waveform 60 + 62 + 64: Unbalance force remaining in the internal combustion engine 10 in the present embodiment

  As indicated by the waveforms 60 + 62 + 64, the unbalance force remaining in the internal combustion engine 10 in the present embodiment is sufficiently small over the entire crank angle θ. The unbalanced force is sufficiently smaller than the unbalanced force (waveform 60 × 2 + 64) when the balance shaft 40 is rotated at a constant speed by the gear mechanism.

  The connecting rod 36 used in the present embodiment can be formed to be significantly lighter and smaller than the gear mechanism. For this reason, according to the configuration of the present embodiment, it is advantageous in reducing the size and weight of the internal combustion engine 10 as compared with the case where the balance shaft 40 is rotated using a gear mechanism, and the quietness superior in the internal combustion engine 10 is achieved. Can be given.

[Modification of Embodiment 1]
FIG. 10 is a diagram for explaining a configuration of a modification of the first embodiment of the present invention. In the first embodiment described above, the CS connection point 32 is provided on the opposite side of the CS eccentric weight 24 across the center of the CS main shaft 22, and the BS connection point 38 is provided between the BS support shaft 44 and the BS. It is provided on the opposite side of the eccentric weight 48 (see FIG. 1). However, the configuration of the present invention is not limited to this. That is, as shown in FIG. 10, the CS connection point 32 is provided on the same side as the CS eccentric weight 24 with respect to the center of the CS main shaft 22, and the BS connection point 38 is set with respect to the center of the BS support shaft 44. It may be provided on the same side as the BS eccentric weight 48.

  11, 12 and 13 show waveforms of inertial force and excitation force generated in accordance with the operation of the above-described modification. The waveforms shown in each figure are given the same reference numerals as those shown in FIG. 7, FIG. 8, and FIG. As shown in FIG. 13, according to the configuration of the present modification, the unbalanced force (waveform 60 + 62 + 64) remaining in the internal combustion engine 10 can be further reduced as compared with the case of the first embodiment. Note that the positions of the CS connection point 32 and the BS connection point 38 are not limited to the positions shown in FIG. 10, and can be appropriately set according to the waveform of the excitation force Y component to be generated by the balance device 30. it can.

  In the first embodiment described above, the internal combustion engine 10 is a single-cylinder engine, but the configuration of the present invention is not limited to this. For example, in a four-cycle two-cylinder engine, pistons of two cylinders reciprocate in the same phase. The present invention may be used to cancel the inertial force generated by these two pistons.

  In the above-described first embodiment, the phase of the center of gravity of the crankshaft 16 and the phase of the center of gravity of the balance shaft 40 are matched at the top dead center and the bottom dead center. It may be different if necessary to gain power. Specifically, the phase of both is within the range of 45 [° CA], within the range of 30 [° CA], within the range of 15 [° CA], or within the range of 5 [° CA]. May be different.

  The three modifications described above can be used not only as modifications of the first embodiment but also as modifications of all other embodiments described later.

  Moreover, in Embodiment 1 mentioned above, although the sliding part 52 hold | maintained by the guide part 54 is made circular, the structure of this invention is not limited to this. The sliding part 52 only needs to be able to linearly move the pivot 50 along the guide part 54, and the shape thereof may be a square or a rectangle with a corner cut.

  Moreover, in Embodiment 1 mentioned above, although the pivot 50 hold | maintained by the guide part 54 is provided in the midpoint of the connection rod 36, the structure of this invention is not limited to this. That is, the pivot 50 of the connecting rod 36 can be provided at an arbitrary point on the connecting rod 36 as long as the balance device 30 can be operated.

  In the first embodiment described above, the BS connection point adjustment mechanism 46 is provided on the balance shaft 40 side, but the configuration of the present invention is not limited to this. That is, the connection point adjusting mechanism may be provided on both the balance shaft 40 and the crankshaft 16 or on the crankshaft 16 side in order to enable the balance device 30 to operate.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 14 is a diagram for explaining the operation of the balance device 66 in the present embodiment. The configuration of the present embodiment can be realized by mounting the balance device 66 shown in FIG. 14 on the internal combustion engine 10 shown in FIG. 1 instead of the balance device 30 shown in FIG. In FIG. 14, elements common to those shown in FIG. 2 are denoted by common reference numerals, and description thereof is omitted or simplified.

  The balance device 66 shown in FIG. 14 includes a guide portion 68 for restricting the track of the connecting rod 36. The guide portion 68 has a groove 70 that is substantially equal to the width of the connecting rod 36. The connecting rod 36 can slide in the groove 70 while being accommodated in the groove 70.

  The guide portion 68 includes a rotating shaft 72 at a portion overlapping the connecting rod 36 in FIG. 14 (originally, it is the back side of the connecting rod 36 and cannot be visually observed). The rotation shaft 72 is provided in a position parallel to the CS main shaft 22 and the BS support shaft 44 and overlapping with the CS-BS center line 56 connecting them. For this reason, the guide part 68 can rotate within the movable plane of the connecting rod 36 while holding the connecting rod 36.

  In FIG. 14, a dot 74 shown on the connecting rod 36 represents the midpoint of the connecting rod 36. In the first embodiment described above, the movement of the connecting rod 36 is regulated so that the midpoint (pivot 50) of the connecting rod 36 moves on the CS-BS center line 56 (see FIG. 2). In this case, the connecting rod 36 always transmits the displacement generated at the CS connecting point 32 to the BS connecting point 38 with a lever ratio of 1: 1.

  In the present embodiment, as shown in FIG. 14, in the situation where the crank angle θ = 0 [° CA], the midpoint 74 of the connecting rod 36 is disengaged on the guide portion 68, that is, on the BS connecting point 38 side. Yes. In this case, the displacement generated at the CS connection point 32 is amplified with an insulator ratio larger than 1 and transmitted to the BS connection point 38. When the crank angle θ exceeds 90 [° CA], the middle point 74 of the connecting rod 36 is disengaged from the lower side of the guide portion 68, that is, the CS connecting point 32 side. In this case, the displacement generated on the CS connection point 32 side is reduced at an insulator ratio of less than 1 and transmitted to the BS connection point 38.

  Thus, according to the configuration of the present embodiment, the displacement generated at the CS connection point 32 can be transmitted to the BS connection point 38 with an appropriately different lever ratio. More specifically, in the region near the top dead center where the crank angle θ is close to 0 [° CA], the balance shaft 40 is further increased with respect to the rotation of the crank angle θ as compared with the case of the first embodiment. It can be rotated at high speed. In a region near the bottom dead center where the crank angle θ is close to 180 [° CA], the balance shaft 40 is rotated more slowly with respect to the rotation of the crank angle θ than in the case of the first embodiment. be able to.

  If the speed profile of the balance shaft 40 changes, the profile of the excitation force generated by the balance shaft 40 will also be different. For this reason, according to the balance device 66 in the present embodiment, it is possible to generate an excitation force profile different from that in the first embodiment.

  The inertial force generated by the piston 12 of the internal combustion engine 10 exhibits various profiles according to various design values. According to the configuration of the present embodiment, excellent quietness is imparted to the internal combustion engine 10 when the profile of the inertial force generated by the piston 12 approximates the profile of the excitation force generated by the balance device 66 shown in FIG. can do.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 15 is a diagram for explaining the operation of the balance device 78 in the present embodiment. The configuration of the present embodiment can be realized by mounting the balance device 78 shown in FIG. 15 in place of the balance device 30 shown in FIG. 2 in the internal combustion engine 10 shown in FIG. The balance device 78 is the same as the balance device 30 shown in FIG. 2 except for the following three points. In FIG. 15, elements common to those shown in FIG. 2 are denoted by common reference numerals and description thereof is omitted or simplified.

(Difference 1)
The balance device 78 of this embodiment includes a balance shaft 80. The BS coupling mechanism 42 is directly attached to the balance shaft 80 without the BS coupling point adjusting mechanism 46 (see FIG. 2).

(Difference 2)
The balance device 78 of this embodiment satisfies the following conditions.
(1) The distance L _CB between the center of the CS main shaft 22 and the center of the BS support shaft 44 is equal to the distance l _cb between the CS connection point 32 and the BS connection point 38.
(2) The rotation radius r1 of the CS connection point 32 is equal to the rotation radius r2 of the BS connection point 38.

(Difference 3)
The balance device 78 of this embodiment includes a guide portion 82. In FIG. 15, an eight-shaped broken line shown in the guide portion 82 indicates the locus 84 of the pivot 50. The guide portion 82 is given a width wider than the diameter of the sliding portion 52 so that the pivot 50 can move along the locus 84.

  In FIG. 15, when the crank angle θ is 0 [° CA], the center line of the connecting rod 36 overlaps the line segment connecting the center of the BS support shaft 44 and the BS connection point 38. Hereinafter, this point is referred to as “first thought point”. At the first thought point, the axial force applied from the connection rod 36 to the BS connection point 38 does not apply a rotational moment to the balance shaft 80. For this reason, the balance shaft 80 is in a state in which it can rotate both in the forward direction and in the reverse direction at the first thought point.

If the crankshaft 16 rotates forward from the first thought point, the CS coupling point 32 is slightly displaced in the (x positive direction, y negative direction). Since the distance between the CS connection point 32 and the BS connection point 38 is always constant, if the above displacement occurs at the CS connection point 32, the BS connection point 38 must be displaced in either direction in order to compensate for the displacement. I do not get.

  If the connecting rod 36 can be freely displaced, the BS coupling point 38 can be displaced in the x positive direction and the x negative direction, that is, in both the forward and reverse directions. If the BS connection point 38 is displaced in the forward rotation direction together with the CS connection point 32, the pivot 50 of the connection rod 36 at the intermediate point inevitably follows a substantially circular locus and is displaced in the forward rotation direction. Will do. On the other hand, if the BS connection point 38 is displaced in the opposite direction to the CS connection point 32, a slight x displacement and a large y displacement occur in the pivot 50 at the intermediate point therebetween. At this time, the pivot 50 is displaced along an 8-shaped locus 84.

  In FIG. 16, the above-mentioned 8-shaped trajectory (hereinafter referred to as “reverse rotation trajectory”) 84 is a trajectory of the pivot 50 accompanying the forward rotation of the BS connection point 38 (hereinafter referred to as “normal rotation trajectory”). FIG. A sliding locus 88 denoted by reference numeral 88 in FIG. 16 represents a shape that the outer wall of the sliding portion 52 follows when the pivot 50 is displaced along the reverse rotation locus 84.

  FIG. 17 is a diagram for explaining the details of the guide portion 82 shown in FIG. 15. As shown in FIG. 17, the guide portion 82 includes a BS side guide 90 at one end thereof. The BS-side guide 90 is provided at a position where the sliding portion 52 is located at the first thought point, and has the same shape as the upper end portion of the sliding locus 88 shown in FIG. According to the BS side guide 90, the sliding portion 52 can be prevented from being displaced along the forward rotation locus 86 at the first thought point, and the sliding portion 52 can be displaced along the reverse rotation locus 84. .

  For the reason described above, in the balance device 78 of the present embodiment (see FIG. 15), when the crankshaft 16 slightly rotates from the first thought point, the sliding portion 52 is always along the reverse rotation locus 84. Can be displaced. At this time, the displacement direction of the BS connection point 38 is necessarily the reverse rotation direction, that is, the x negative direction. If the BS coupling point 38 is displaced in the x negative direction even slightly from the first thought point, the axial force generated by the coupling rod 36 gives a rotational moment to the balance shaft 40. Thereafter, until the crank angle θ reaches 180 [° CA], the balance shaft 80 receives the rotational moment and maintains a stable reverse rotation.

  When the crank angle θ reaches 180 [° CA], the line connecting the center of the BS support shaft 44 and the BS connection point 38 overlaps the center line of the connection rod 36 again. Hereinafter, this point is referred to as a “second thought point”. At the second thought point, similarly to the first thought point, the balance shaft 80 can be rotated in both the forward direction and the reverse direction.

  As shown in FIG. 17, the guide portion 82 in this embodiment includes a CS-side guide 92 on the opposite side of the BS-side guide 90. The CS-side guide 92 is provided at a position where the sliding portion 52 is located at the second thought point, and has the same shape as the lower end portion of the sliding locus 88 shown in FIG. According to the CS-side guide 92, it is possible to prevent the sliding portion 52 from being displaced along the normal rotation locus 86 and to displace the sliding portion 52 along the reverse rotation locus 84 at the second thought point. .

  Due to the restriction by the CS side guide 92, the sliding portion 52 is always displaced along the reverse rotation locus 84 when the crankshaft 16 rotates from the second thought point. If a slight displacement occurs, a rotational moment in the reverse rotation direction is stably applied to the balance shaft 80 until the first thought point is restored. By repeating the above operation, the balance shaft 80 can be rotated at a non-uniform speed in the direction opposite to the rotation direction of the crankshaft 16 also in the present embodiment.

  As shown in FIG. 16, when the pivot 50 moves along the reverse rotation locus 84, the outer wall of the sliding portion 52 follows a sliding locus 88 having a constriction at the center. For this reason, the inner wall of the guide portion 82 may be formed of a set of curves, like the sliding locus 88. However, the function required for the guide portion 82 in the present embodiment is only to restrict the movement of the sliding portion 52 at the first thought point and the second thought point.

  That is, in this embodiment, if the movement of the sliding portion 52 can be appropriately restricted between the first thought point and the second thought point, the balance shaft 80 is stably reversely rotated by the axial force of the connecting rod 36 in the process between them. Can be made. For this reason, the guide part 82 does not need to contact the sliding part 52 between the first thought point and the second thought point.

  In FIG. 17, the guide portion 82 includes straight side walls 94 and 96 between the BS side guide 90 and the CS side guide 92. Since these side walls 94 and 96 are linear, manufacture is easy compared with the curved side wall which the sliding locus | trajectory 88 (refer FIG. 16) has. Further, these side walls 94 and 96 do not interfere with the sliding portion 52 that is displaced along the sliding locus 88. For this reason, according to the guide part 82 as shown in FIG. 17, a desired function is realizable, simplifying a manufacturing process.

  As described above, according to the configuration of the present embodiment, the balance shaft 80 can be rotated at a non-constant speed in the direction opposite to the rotation direction of the crankshaft 16 by the structure via the connecting rod 36. For this reason, also with the configuration of the present embodiment, as in the case of the first or second embodiment, it is possible to realize a small internal combustion engine 10 that is excellent in quietness.

  In the third embodiment described above, the pivot 50 and the sliding portion 52 of the connecting rod 36 correspond to the “regulating portion” in the fourth invention.

[Modification of Embodiment 3]
FIG. 18 shows an example of another configuration that can be used as the guide portion 82 in the third embodiment. In the third embodiment described above, the straight side walls 94 and 96 are provided between the BS side guide 90 and the CS side guide 92. In the example shown in FIG. 18, those side walls 94 and 96 are omitted. The guide portion 82 in the third embodiment may be realized with such a simple configuration.

Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described with reference to FIGS. FIG. 19 is a diagram for explaining the configuration of the present embodiment. The configuration of the present embodiment can be realized by adding a moment application mechanism 98 to the configuration of the third embodiment described above. In FIG. 19, elements common to the elements shown in FIG. 1 or FIG. 15 are denoted by common reference numerals, and description thereof is omitted or simplified.

  The moment applying mechanism 98 includes a cam 100. The cam 100 is mounted on the BS support shaft 44. The cam 100 has a cam nose 106 that rotates together with the BS support shaft 44.

  The moment application mechanism 98 also includes spring members 102 and 104. The spring members 102 and 104 are arranged so as to transmit the spring force to the side surface of the cam 100 at a position where the phase is shifted by 180 [deg].

  The configuration of the present embodiment includes a balance device 78 similar to that of the third embodiment. In the balance device 78, a state in which the rotational moment is not transmitted to the balance shaft 80 occurs at the first thought point and the second thought point. The moment applying mechanism 98 is a mechanism for applying to the balance shaft 80 a rotational moment opposite to the rotational direction of the crankshaft 16 under these conditions.

  FIG. 20 is a diagram for explaining the operation of the configuration of the present embodiment. FIG. 21 shows the magnitude of spring torque received by the cam 100 from the spring members 102 and 104 under the conditions (1) to (8) shown in FIG. In FIG. 21, the area where the spring torque is negative is an area where the spring members 102 and 104 are compressed, and the area where the spring torque is positive is an area where the spring members 102 and 104 are opened.

  20 and 21, in the sections (1) to (2), the axial force 108 of the connecting rod 36 generates a moment 110 that rotates the balance shaft 80, and the spring member 102 is rotated with the rotation of the cam 100. A displacement 112 in the compression direction is generated. In the sections (2) to (4), the spring member 102 is displaced 112 in the release direction, and the moment 110 is transmitted to the balance shaft 80 via the cam 100. The configuration of the present embodiment is designed so that the first thought point is included in the sections (2) to (4). When the moment 110 is transmitted to the balance shaft 80 in this section, the balance shaft 80 can maintain a stable reverse rotation.

  The cam 100 of this embodiment is formed so that the spring member 102 does not expand and contract in the sections (4) to (5). For this reason, the balance shaft 80 maintains reverse rotation mainly by the axial force of the connecting rod 36 in this section. In the sections (5) to (8), due to the function of the spring member 104, the same moment 110 as in the sections (1) to (4) is generated. The configuration of the present embodiment is designed so that the second thought point is included in the section (6) to (8) in which the spring force generates the moment 110. For this reason, according to the configuration of the present embodiment, the balance shaft 80 can be stably rotated reversely to the crankshaft 16 in the entire rotation range.

[Modification of Embodiment 4]
By the way, in Embodiment 4 mentioned above, the area of (4)-(5) and the area of (8)-(1) shown in FIG.20 and FIG.21 are made into the area which does not generate | occur | produce a spring torque. However, the configuration of the present invention is not limited to this. In these sections, a sufficient moment can be generated by the axial force of the connecting rod 36. Therefore, in order to smooth the drive torque, these sections are compressed by the spring members 102 and 104 as shown in FIG. It may be used as a section for the purpose.

  Further, in the above-described fourth embodiment, by using the two spring members 102 and 104, a desired rotational moment is generated near both the first thought point and the second thought point. However, the configuration of the present invention is not limited to this. FIG. 23 shows a configuration using a cam 114 having two cam noses. According to such a configuration, a desired rotational moment can be generated in one spring member 102 at both the first thought point and the second thought point.

  In the fourth embodiment described above, the cam 100 is mounted on the BS support shaft 44 to generate a rotational moment. However, the configuration of the present invention is not limited to this. FIG. 24 shows an example in which two cam mechanisms 116 and 118 are provided on the side of a stationary member such as a cylinder block. Each of the cam mechanisms 116 and 118 has a function of converting the rotational operation of the BS connection point 38 into spring torque. According to such a configuration, as in the case of the fourth embodiment, it is possible to appropriately generate a rotational moment for stably rotating the balance shaft 80 in the reverse direction.

  In the fourth embodiment described above, the cam 100 and the spring members 102 and 104 are newly incorporated into the internal combustion engine 10 in order to give a desired rotational moment to the balance shaft 80. However, the configuration of the present invention is not limited to this. For example, in-cylinder direct injection gasoline engines and diesel engines include a high-pressure fuel injection pump. The high-pressure fuel injection pump may include a cam that operates in synchronization with the operation cycle of the internal combustion engine and a spring member that engages with the cam. The rotational moment generated in the fourth embodiment may be generated using these existing cams and spring members.

  In the fourth embodiment described above, the moment applying mechanism 98 is incorporated in the configuration of the third embodiment. Compared with the balance device 30 of the first embodiment and the balance device 66 of the second embodiment, the balance device 78 of the third embodiment is more likely to cause self-locking at the first thought point and the second thought point. For this reason, the configuration of the fourth embodiment exhibits particularly high utility when the configuration of the third embodiment is assumed. However, the condition of the combination is not limited to this. That is, the moment applying mechanism 98 in the fourth embodiment may be combined with the configuration of the first or second embodiment.

Embodiment 5. FIG.
Next, a fifth embodiment of the present invention will be described with reference to FIGS. FIG. 25 is a diagram for explaining the configuration of the present embodiment. The configuration of the present embodiment can be realized by adding a moment applying mechanism 120 to the configuration of the third embodiment described above. In FIG. 25, elements common to the elements shown in FIG. 1 or FIG. 15 are denoted by common reference numerals, and description thereof is omitted or simplified.

  In the present embodiment, the moment application mechanism 120 includes a first spring member 122. The first spring member 122 includes a spring material 124 and a contact portion 126. The abutting portion 126 is provided so as to abut on the BS coupling point 38 at the first thought point where the axis of the coupling rod 36 overlaps the center of the BS support shaft 44. In addition, the spring member 124 is provided so as to generate a spring force that urges the BS connection point 38 in the counterclockwise direction in the drawing.

  The moment application mechanism 120 also includes a second spring member 128. The second spring member 128 is provided at a position that is approximately 180 [deg] out of phase with the first spring member 122. The second spring member 128 includes a spring material 132 and a contact portion 130. The contact portion 130 is provided so as to contact the BS connection point 38 at a second thought point indicating a state in which the balance shaft 80 is rotated by 180 [deg] from the first thought point. In addition, the spring member 132 is provided so as to generate a spring force that urges the BS connection point 38 in the counterclockwise direction in the drawing.

  FIG. 26 is a diagram for explaining the operation of the configuration of the present embodiment. FIG. 27 shows the magnitude of the urging force in the x direction received by the BS connection point 38 under the conditions (1) to (8) shown in FIG. As shown in FIG. 26, in the sections (1) to (2), as the crankshaft 16 rotates, an axial force 134 that causes the first spring member 122 to generate a displacement 136 in the reduction direction is generated. In the sections (3) to (4), the displacement 136 in the extension direction is generated in the first spring member 122. A negative reaction force 138 in the x negative direction acts on the BS connection point 38 in almost the entire region (1) to (4).

  When the BS connection point 38 is located above the center of the BS support shaft 44, the x negative reaction force 138 generates a moment that rotates the balance shaft 80 in the direction opposite to the crankshaft. In the present embodiment, the balance device 78 is designed so that the first thought point is included in the sections (1) to (4). Therefore, according to this device 78, the balance shaft 80 can be stably rotated in the reverse direction in the vicinity of the first thought point.

  In FIG. 26, in the sections (5) to (8), the second spring member 128 biases the BS connection point 38 in the positive x direction. When the BS connection point 38 is located below the center of the BS support shaft 44, the force in the positive x direction acting on the BS connection point 38 rotates the balance shaft 80 in the direction opposite to the rotation direction of the crankshaft 16. Generate moments. In the present embodiment, the balance device 78 is designed so that the second thought point is included in the sections (5) to (8). Therefore, according to this device 78, the balance shaft 80 can be stably rotated in the reverse direction in the vicinity of the second thought point.

  As described above, according to the configuration of the present embodiment, the balance shaft 80 can be stably rotated in the reverse direction with respect to the crankshaft 16 as in the case of the fourth embodiment. For this reason, the structure of this embodiment can also provide a small internal combustion engine 10 that is excellent in quietness.

Embodiment 6 FIG.
[Configuration of Embodiment 6]
Next, a sixth embodiment of the present invention will be described with reference to FIGS. FIG. 28 is a diagram for explaining the configuration of the sixth embodiment of the present invention. The configuration of the present embodiment is the same as the configuration of the first embodiment (see FIG. 1) except that the balance device 30 is replaced with a balance device 140 having an offset structure.

  In the present embodiment, the crankshaft 16 of the internal combustion engine 10 is used in an offset crank manner. In FIG. 28, a broken line denoted by reference numeral 142 is an axis of the reciprocating motion of the piston 12. In the internal combustion engine 10, the axis 144 of the crankshaft 16 is disposed at a position separated in parallel by a distance H from the axis 142 of the piston 12.

(Effect of offset crank)
FIG. 29 is a diagram for explaining the effect obtained by the offset crank method. The figure on the left side of FIG. 29 shows the structure of the comparative example. In this structure, the center of the CS main shaft 22 overlaps the axis 142 of the reciprocating motion of the piston 12. The graphic on the right side of FIG. 29 schematically shows a structure using the offset crank method. In this structure, the center of the CS main shaft 22 is offset from the axis 142 of the reciprocating motion of the piston 12 by a distance H.

  In FIG. 29, an arrow denoted by reference numeral 146 represents the combustion pressure acting on the piston 12. The combustion pressure 146 takes a large value from around the piston 12 slightly exceeding the top dead center in the explosion stroke. Each of the two figures shown in FIG. 29 shows a state in which a large combustion pressure 146 is acting on the piston 12.

  The piston 12 is connected to a crankpin 18 via a connecting rod 14. Therefore, a reaction force 148 of the combustion pressure 146 is input to the piston 12 from the connecting rod 14. If the connecting rod 14 is inclined by δ [deg] with respect to the axis 142 of the piston 12, the reaction force 148 includes a horizontal component 150 represented by (reaction force 148 * sin δ). The horizontal component 150 acts as a force for pressing the piston 12 against the cylinder inner wall.

  In the structure of the comparative example in which the axis 142 of the reciprocating motion of the piston 12 overlaps the center of the CS main shaft 22, a large combustion pressure 146 is applied to the piston 12 when the connecting rod 14 is inclined with respect to the axis 142. For this reason, in this configuration, a large horizontal component 150 is generated, and the friction of the piston 12 tends to increase.

  According to the offset crank method, the inclination angle δ of the connecting rod 14 when the large combustion pressure 146 acts on the piston 12 can be set to a small value. For this reason, according to this configuration, the piston 12 can reciprocate in the cylinder without receiving the large horizontal component 150. For this reason, according to the configuration of the present embodiment, the friction of the piston 12 can be reduced and the fuel consumption can be improved as compared with the configuration of the comparative example.

(Non-objectivity due to offset)
FIG. 30 is a diagram for explaining the non-target property of the speed profile indicated by the piston 12 in the present embodiment. In FIG. 30, the piston 12 is located at the top dead center at the crank angle θ = 0 [° CA], and is located at the bottom dead center at θ = 180 [° CA].

θ = 90 [° CA] and θ = 270 [° CA] are intermediate points between the top dead center and the bottom dead center with respect to the crank angle θ. However, there is a large difference between the inclination angle δ90 of the connecting rod 14 at θ = 90 [° CA] and the inclination angle δ270 at θ = 270 [° CA] due to the influence of the offset crank. As a result, the piston stroke PS90 generated at a crank angle θ = 90 [° CA] and the piston stroke PS270 generated at θ = 270 [° CA] have different values. Naturally, the stroke (PS180-PS90) that occurs when θ changes from 90 to 180 [° CA] is different from the stroke that occurs when θ changes from 180 to 270 [° CA] (PS270-PS180). Value.

  Thus, in the internal combustion engine 10 using the offset crank method, the crank angle θ is a forward process from the top dead center to the bottom dead center and a return path from the bottom dead center to the top dead center. The piston 12 exhibits an asymmetric displacement profile. If the displacement profile is asymmetric, the inertial force that accompanies the displacement is also asymmetric. For this reason, in order to cancel the inertial force generated by the piston 12 of the internal combustion engine 10 with high accuracy, it is effective to generate an asymmetrical excitation force in the balance device 140 as well.

(Configuration of balance device of this embodiment)
FIG. 31A shows the configuration of the balance device 140 used in the present embodiment. The balance device 140 is implemented except that the CS-BS center line 56 that connects the center of the CS main shaft 22 and the center of the BS support shaft 44 is offset from the axis 152 of the guide portion 54 by a distance h. This is the same as the balance device 30 (see FIG. 2) in the first embodiment. In FIG. 31A, elements common to the elements illustrated in FIG. 2 are denoted by common reference numerals and description thereof is omitted or simplified.

  In the balance device 140 shown in FIG. 31A, the sliding portion 52 of the connecting rod 36 linearly moves inside the guide portion 54 as the crankshaft 16 rotates. At this time, the pivot 50 of the connecting rod 36 moves along the axis 152 of the guide portion 54. When the pivot 50 moves on the CS-BS center line 56, the BS rotation angle α is determined by the forward process in which the crank angle θ changes from 0 to 180 [° CA], and θ is 180 to 360 [° CA]. The target change profile is shown in the process of the return path that changes up to. However, when the pivot 50 moves on the axis 152 deviating from the CS-BS center line 56, the profile of the BS rotation angle α is asymmetric in the forward process and the return process.

Such non-objectivity of the BS rotation angle α occurs due to the pivot 50 moving on an axis 152 that is off the CS-BS center line 56. 31 (B), 31 (C), and 31 (D) show examples of other balance devices in which such asymmetry occurs. Specifically, FIG. 31B shows a balance device 154 in which the center of the BS support shaft 44 is offset from the axis 152 of the guide portion 54 by a distance h. FIG. 31C shows a balance device 156 in which the center of the CS main shaft 22 is offset from the axis 152 of the guide portion 54 by a distance h. FIG. 31D shows a balance device 158 in which both the center of the CS main shaft 22 and the center of the BS support shaft 44 are offset from the axis 152 by a distance h in opposite directions. These balance devices 154, 156, and 158 can be used by appropriately replacing the balance device 140 shown in FIG. 31A according to the asymmetry of the inertial force generated by the piston 12.

(Excitation force generated by the balance device of this embodiment)
Hereinafter, the excitation force generated by the balance device 140 of this embodiment will be described with reference to FIGS. 32 to 34 together with FIG. Various dimensions of the balance device 140 are various parameters that affect the profile of the BS rotation angle α. Here, the ratio r1 / lcb between the rotation radius r1 of the CS connection point 32 and the length lcb of the connection rod 36 is fixed to a general value, and the ratio h / r1 between the offset value h and the rotation radius r1 is set to “− A description will be given of the results of the simulation performed by changing to “a”, “−b”, and “+ a”. In addition, the code | symbol attached | subjected to a and b represents the difference in the direction which offset the distance h.

  FIG. 32 shows the relationship between the crank angle θ and the BS angular velocity dα / dθ. Since the balance shaft 40 rotates in the opposite direction to the crankshaft 16, if the α shows the same change as θ, the BS angular velocity dα / dθ becomes −1. For example, in the waveform of “−a”, there is little change of α with respect to θ in the forward path from the top dead center to the bottom dead center, and the asymmetrical tendency in the reverse direction from the bottom dead center to the top dead center. Sex is appearing. In addition, the “−b” waveform shows weak non-objectivity compared to the “−a” waveform. Further, the “+ a” waveform shows non-objectivity opposite to the asymmetry of “−a”.

  As described above, the balance device 140 according to the present embodiment can generate the BS angular velocity dα / dθ having an asymmetric profile between the forward path and the return path. As described above, centrifugal force proportional to the square of angular velocity and reaction force against angular acceleration act on the balance shaft 40. And the balance axis | shaft 40 generate | occur | produces the excitation force according to the synthesized value of those centrifugal force and reaction force. In the present embodiment, since the BS angular velocity dα / dθ has an asymmetric profile, the excitation force generated by the balance shaft 40 also has an asymmetric profile in the forward path and the return path, similar to the inertial force of the piston 12.

FIG. 33 is a diagram showing the excitation force obtained by synthesizing the excitation force Y component generated by the crankshaft 16 and the excitation force Y component generated by the balance shaft 40 in comparison with the inertial force of the piston 12. The five types of waveforms shown in FIG. 33 are as follows.
Waveform 60 × 2: equivalent to twice the excitation force Y component generated by the crankshaft 16 (see FIG. 8)
Waveform 160: Asymmetric inertial force generated by piston 12 Waveform 162: Equivalent to synthesis of excitation force Y component generated by balance shaft 40 and excitation force Y component generated by crankshaft 16 under the condition of “−a” 164: Equivalent to the synthesis of the excitation force Y component generated by the balance shaft 40 under the condition “−b” and the excitation force Y component generated by the crankshaft 16 Waveform 166: the balance shaft 40 under the condition “+ a” Equivalent to the composition of the excitation force Y component generated by the crankshaft 16 and the excitation force Y component generated by the crankshaft 16

  The exciting force generated by the crankshaft 16 has a sinusoidal shape with almost no distortion with respect to the change in the crank angle θ. When the balance shaft 40 rotates at the same speed as the crankshaft 16, the excitation force generated by both of them is substantially the same. In this case, the inertial force generated by the balance device 140 shows a substantially target profile in the forward path and the return path as indicated by the waveform 60 × 2. On the other hand, the waveforms 162, 164, and 166 all have asymmetric profiles. Since the inertial force generated by the piston 12 is asymmetric, the waveforms 162, 164, and 166 have a higher possibility than the waveform 60 × 2 in canceling the inertial force of the piston 12.

FIG. 34 shows waveforms of the unbalanced force remaining in the internal combustion engine 10 as a result of combining the various exciting forces shown in FIG. 33 with the inertial force of the piston 12. The meaning of the waveform shown in FIG. 34 is as follows.
Waveform 160 + 162: Unbalanced force remaining in the internal combustion engine 10 under the condition “−a” Waveform 160 + 164: Unbalanced force remaining in the internal combustion engine 10 under the condition “−b” Waveform 160 + 166: Under the condition “+ a” Unbalance force remaining in internal combustion engine 10 Waveform 160 + 60 × 2: Unbalance force remaining in internal combustion engine 10 when balance shaft 40 is operated by a gear mechanism

  As shown in FIG. 34, under any condition, according to the balance device 140 of this embodiment, the remaining unbalance force can be reduced as compared with the case where the balance shaft 40 is operated by a gear mechanism. it can. In particular, in this simulation, when the condition “−b” is used, the remaining unbalanced force can be set to a sufficiently small value (see waveform 160 + 164). As described above, according to the configuration of the present embodiment, even when the offset crank method is used, excellent quietness is imparted to the internal combustion engine 10 with a compact mechanism using the connecting rod 36. be able to.

Embodiment 7 FIG.
[Configuration of Embodiment 7]
Next, a seventh embodiment of the present invention will be described with reference to FIGS.
FIG. 35 is a diagram for explaining the configuration of a balance device 168 used in Embodiment 7 of the present invention. The configuration of the present embodiment is the same as the configuration of the first embodiment (see FIG. 1) or the configuration of the sixth embodiment (see FIG. 28) except that the balance device 30 is replaced with a balance device 168. It is the same.

  The balance device 168 of the present embodiment is the same as that of the second embodiment except that the center of the rotation shaft 72 of the guide portion 68 is offset from the CS-BS center line 56 by a distance h. This is the same as the balance device 66 (see FIG. 14). In FIG. 35, the same or common elements as those shown in FIG. 14 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  The balance device 168 of the present embodiment corresponds to the offset crank method, similarly to the balance device 140 of the sixth embodiment. In other words, the balance device 168 shown in FIG. 35 is similar to the balance device 140 of the sixth embodiment in the process of changing the crank angle θ to 0 to 180 [° CA] and θ is 180 to 360 [° CA]. In this process, the balance shaft 40 is rotated asymmetrically at a non-uniform speed.

  In the balance device 168 shown in FIG. 35, if the center of the rotation shaft 72 of the guide portion 68 overlaps with the CS-BS center line 56, the BS rotation angle α is set with the crank angle θ = 0 [° CA] as a boundary. The target change profiles are shown on the positive side (90 [° CA] side) and the negative side (270 [° CA] side). However, when the center of the rotation shaft 72 is deviated from the CS-BS center line 56, the above objectivity is lost, and the change profile of the BS rotation angle α is asymmetric.

  36, 37, and 38 respectively correspond to FIGS. 32, 33, and 34 in the sixth embodiment described above. The description of these figures is the same as the explanation of the corresponding figures, so that the duplicate description is omitted here.

  As shown in FIG. 36 to FIG. 38, the balance device 168 in this embodiment also generates a non-target excitation force suitable for canceling the asymmetric inertial force as in the case of the sixth embodiment. Can do. For this reason, also in the configuration of the present embodiment, as in the case of the sixth embodiment, excellent quietness is imparted to the internal combustion engine 10 using the offset crank technique without hindering the reduction in size and weight. be able to.

Embodiment 8 FIG.
[Configuration of Embodiment 8]
Next, an eighth embodiment of the present invention will be described with reference to FIGS.
FIG. 39 shows the configuration of an internal combustion engine equipped with a balance device 170 according to the eighth embodiment of the present invention. The balance device 170 has a connecting rod 36 that is inclined with respect to the axis 172 of the reciprocating motion of the piston 12 as in the first to seventh embodiments. Here, it is assumed that the inclination angle between the axis 172 of the piston 12 and the connecting rod 36 is “β” °. In addition, a straight line that passes through the CS main shaft 22 and is parallel to the axis 172 of the piston 12 and a straight line that passes through the BS support shaft 44 are referred to as “CS axis 174” and “BS axis 176”, respectively.

  The balance device 170 according to this embodiment includes a crankshaft 178 and a balance shaft 180. The crankshaft 178 and the balance shaft 180 have a CS eccentric weight 182 and a BS eccentric weight 184, respectively. The balance device 170 according to the present embodiment is the same as the balance device according to the first embodiment except that the CS eccentric weight 182 and the BS eccentric weight 184 have the centers of gravity 186 and 188 at the positions indicated by the points ● in FIG. 30 (see FIG. 1).

  FIG. 40 is a view for explaining the principle by which the balance device 170 of the present embodiment cancels the excitation force generated in the internal combustion engine. Specifically, the left side of FIG. 40 shows conditions that the CS eccentric weight 182 and the BS eccentric weight 184 must satisfy in order to cancel the excitation force Fp caused by the piston 12 and the excitation force Fc caused by the connecting rod 14. FIG. Further, the right side of FIG. 40 is a diagram showing conditions that the CS eccentric weight 182 and the BS eccentric weight 184 should satisfy in order to cancel the excitation force Fc caused by the connecting rod 36. Hereinafter, similarly to the description in the first embodiment, the weight of the piston 12 is represented by “mp” and the weight of the connecting rod is represented by “mc”. Furthermore, in this embodiment, the weight of the connecting rod 36 is represented by “mr”.

  Each of the two figures shown in FIG. 40 represents a state when the piston 12 reaches top dead center. At this time, the piston 12 and the connecting rod 14 generate an excitation force (Fp + Fc) corresponding to “mp + mc” upward in the figure along the axis 172 of the reciprocating motion of the piston 12. In order to cancel this excitation force (Fp + Fc), the CS eccentric weight 182 and the BS eccentric weight 184 need to generate an excitation force of the same magnitude downward in the figure.

  In the present embodiment, in order to meet the above requirements, as shown on the left side of FIG. 40, the CS eccentric weight 182 is assigned a downward excitation force corresponding to “mc + mp / 2” in the figure. Further, the BS eccentric weight shares a downward excitation force in the figure corresponding to “mp / 2”. According to such a setting, the excitation force (Fp + Fc) generated by the piston 12 and the connecting rod 14 at the top dead center can be canceled appropriately.

  Under the situation where the piston 12 reaches the bottom dead center, the piston 12 and the connecting rod 14 generate an excitation force (Fp + Fc) whose direction is reversed from the case of the top dead center. At this time, the CS eccentric weight 182 and the BS eccentric weight 184 also generate an excitation force whose directions are reversed. For this reason, according to said setting, an exciting force can be negated also in a bottom dead center.

  Between the top dead center and the bottom dead center, the piston 12 only moves up and down along the axis 172 of the reciprocating motion of the piston 12 and does not generate an excitation force other than the axial direction. The connecting rod 14 rotates around the CS main shaft 22 and generates an excitation force Fc corresponding to a centrifugal force having a weight mc. At this time, the CS eccentric weight 182 that rotates in the same manner generates an excitation force corresponding to the centrifugal force of the weight “mc + mp / 2”. Then, the excitation force Fc caused by the connecting rod 14 is canceled by the portion corresponding to “mc” in the excitation force of the CS eccentric weight 182. Further, the remaining portion of the excitation force generated by the CS eccentric weight 182, that is, the portion corresponding to “mp / 2” is canceled out by the excitation force of the BS eccentric weight 184 rotating in the direction opposite to the CS eccentric weight 182. As described above, according to the conditions shown on the left side of FIG. 40, the excitation force (Fp + Fc) accompanying the movement of the piston 12 and the connecting rod 14 can always be canceled by the CS eccentric weight 182 and the BS eccentric weight 184.

  The figure on the right side of FIG. 40 shows a state in which the connecting rod 36 has reached the operating end on the upper right side in the figure in synchronization with the piston 12 reaching top dead center. In this state, the connecting rod 36 emits an excitation force Fr toward the upper right in the figure at an inclination angle of β ° with respect to the CS axis 174. In the present embodiment, in order to cancel out the excitation force Fr, the CS eccentric weight 182 and the BS eccentric weight 184 are respectively left-downward in the figure corresponding to the weight of “mr / 2” under the condition of top dead center. Generate excitation force.

  Under the situation shown in FIG. 40, the CS eccentric weight 182 and the BS eccentric weight 184 each generate an excitation force corresponding to the weight “mr / 2”. Those excitation forces are directed to the lower left in the figure at an angle of β ° with respect to the CS axis 174 and the BS axis 176. According to these excitation forces, the excitation force Fr caused by the connecting rod 36 can be canceled properly.

  When the piston 12 reaches the bottom dead center, the connecting rod 36 generates an excitation force Fr corresponding to the weight mr in the downward left direction in the drawing. At this time, the CS eccentric weight 182 and the BS eccentric weight 184 generate an excitation force in the upper right direction in the drawing. For this reason, according to said setting, the excitation force resulting from the connection rod 36 can be negated also at a bottom dead center.

  Between the top dead center and the bottom dead center, the connecting rod 36 does not generate a large excitation force. On the other hand, the weight “mr / 2” applied to the CS eccentric weight 182 and the weight “mr / 2” applied to the BS eccentric weight 184 generate an excitation force while rotating in opposite directions. These excitation forces are canceled out because they are opposite to each other.

  As described above, when the CS eccentric weight 182 and the BS eccentric weight 184 satisfy the conditions shown on the right side of FIG. 40, the excitation force accompanying the movement of the connecting rod 36 is always canceled by the CS eccentric weight 182 and the BS eccentric weight 184. be able to.

  In the present embodiment, the CS eccentric weight 182 and the BS eccentric weight 184 are combined with the conditions shown on the left side and the right side of FIG. Specifically, the CS eccentric weight 182 and the BS eccentric weight 184 are given a weight and a center of gravity that satisfy the following conditions, respectively.

<CS eccentric weight>
When the piston 12 reaches top dead center, an excitation force is generated by combining two excitation forces having the following magnitudes and directions.
(1) Size: corresponding to weight (mc + mp / 2) Direction: direction opposite to the excitation force Fp (hereinafter referred to as “anti-Fp direction”)
(2) Size: corresponding to weight (mr / 2) Direction: direction opposite to the excitation force Fr (hereinafter referred to as “anti-Fr direction”)

<BS eccentric weight>
When the piston 12 reaches top dead center, an excitation force is generated by combining two excitation forces having the following magnitudes and directions.
(1) Size: corresponding to weight (mp / 2) Direction: anti-Fp direction (2) Size: corresponding to weight (mr / 2) Direction: anti-Fr direction

  FIG. 41 is an enlarged view of the crankshaft 178 shown in FIG. 39, that is, the crankshaft 178 used in this embodiment. The crankshaft 178 has a weight and a center of gravity that satisfy the above conditions. Specifically, the crankshaft 178 has a weight of approximately (mc + mp / 2 + mr / 2), and has a center of gravity 186 at a position indicated by a point ● in FIG.

  If the crankshaft 178 cancels only the excitation force (Fp + Fc) caused by the piston 12 and the connecting rod 14, it is desirable that the position of the center of gravity 186 at the top dead center overlaps the CS axis 174. On the other hand, in the present embodiment, the position of the center of gravity 186 is shifted from the CS axis 174 to the side opposite to the Fr direction by βcs ° in order to cancel the excitation force Fr caused by the connecting rod 36. That is, the crankshaft 178 of this embodiment has a center of gravity 186 on the opposite side of the CS connection point 32 with respect to the CS axis 174. The deviation angle βcs ° of the center of gravity 186 is necessarily smaller than the inclination angle β ° of the connecting rod 36.

  FIG. 42 is a perspective view of the crankshaft 178. FIG. Here, it is assumed that the connecting rod 36 is disposed on the left side of the crankshaft 178. The crankshaft 178 has two CS eccentric weights 182 across the crankpin 18. The exciting force (Fp + Fc) of the piston 12 and the connecting rod 14 acts on the crankpin 18. For this reason, it is desirable that the weight “mc + mp / 2” for canceling the force is evenly distributed between the two CS eccentric weights 182. On the other hand, the excitation force Fr caused by the connecting rod 36 acts near the left end of the crankshaft 178 in the drawing. When the weight for canceling this force is applied to the CS eccentric weight 182 on the right side in the figure, the excitation force Fr generated by the connecting rod 36 and the excitation force generated by the CS eccentric weight 182 on the right side in the figure are the crankshaft 178. Gives a large moment. Therefore, it is desirable that the weight “mr / 2” for canceling the excitation force Fr caused by the connecting rod 36 is given to the CS eccentric weight 182 on the side close to the connecting rod 36.

  In the present embodiment, in response to the above request, only the half weight of “mc + mp / 2” is given to the CS eccentric weight 182 on the right side in the drawing. The center of gravity of the CS eccentric weight 182 alone exists at a position where it overlaps the CS axis 174 at the top dead center. In addition, the CS eccentric weight 182 on the left side in the figure is given all the weight of “mr / 2” in addition to half the weight of “mc + mp / 2”. At this time, the weight of “mr / 2” is given to the CS eccentric weight 182 on the left side in the drawing so that the center of gravity of the two CS eccentric weights 182 becomes the center of gravity 186 shown in FIG. According to such setting, the exciting force Fr caused by the connecting rod 36 can be canceled without applying a large moment to the crankshaft 178.

  FIG. 43 is an enlarged view of the balance shaft 180 shown in FIG. 39, that is, the balance shaft 180 used in this embodiment. Here, it is assumed that the connecting rod 36 is disposed on the left side of the balance shaft 180. The BS eccentric weight 184 of the balance shaft 180 has a large diameter portion 190 and a small diameter portion 192. The large-diameter portion 190 is provided in the vicinity of one end 194 on the side connected to the connecting rod 36. The small diameter portion 192 is provided on the other end 196 side of the balance shaft 180.

  The BS eccentric weight 184 is generally given a weight of “mp / 2 + mr / 2”. Of this weight, the weight “mp / 2” for canceling the excitation force Fp caused by the piston 12 is equally distributed to the large diameter portion 190 and the small diameter portion 192. On the other hand, the weight “mr / 2” for canceling the excitation force Fr caused by the connecting rod 36 is given only to the large diameter portion 190. As a result, the large diameter portion 190 has a larger outer diameter than the small diameter portion 192.

  The center of gravity 188 of the BS eccentric weight 184 is provided on the opposite side of the BS connection point 38 across the BS axis 176 as in the case of the crankshaft 178 (see FIG. 39). Specifically, the center of gravity 188 of the BS eccentric weight 184 is shifted from the BS axis 176 in the inclination direction of the connecting rod 36 by a certain angle. This deviation angle is inevitably smaller than the inclination angle β ° of the connecting rod 36. According to such setting, the exciting force Fr caused by the connecting rod 36 can be canceled without applying a large moment to the balance shaft 180.

  FIG. 44 is a view for explaining the operation of the internal combustion engine equipped with the balance device 170 of the present embodiment. Specifically, FIG. 44 shows the state of the internal combustion engine in increments of 45 [° CA] from 0 [° CA] to 360 [° CA]. In the figure, the excitation force generated by the CS eccentric weight 182 is indicated as Fcs, and the excitation force generated by the BS eccentric weight 184 is indicated as Fbs. Note that these excitation forces Fcs and Fbs are shown in two parts, for easy understanding, an excitation force for canceling (Fp + Fc) and an excitation force for canceling Fr. As shown in FIG. 44, according to the configuration of the present embodiment, not only the excitation force (Fp + Fc) caused by the piston 12 and the connecting rod 14 but also the excitation force Fr caused by the connecting rod 36 is always properly canceled out. be able to.

[Modification of Embodiment 8]
FIG. 45 is a perspective view of another example of a balance shaft applicable to the balance device 170 of the present embodiment. A balance shaft 198 shown in FIG. 45 has a BS eccentric weight 200. The BS eccentric weight 200 is formed so that the outer diameter gradually decreases from one end 194 to the other end 196 on the side connected to the connecting rod 36. According to such a configuration, as in the case of the balance shaft 180 shown in FIG. 43, the weight mr for canceling the excitation force Fr caused by the connecting rod 36 is placed on the one end 194 side on the other end 196 side. In comparison, it can be reflected greatly. Therefore, even with the balance shaft 198 shown in FIG. 45, the excitation force Fr can be canceled without causing a large moment.

  By the way, in the above-described eighth embodiment, the weight for canceling the excitation force Fr caused by the connecting rod 36 is largely reflected on the side closer to the connecting rod 36. However, this feature is not essential to the present invention. That is, the weight “mr / 2” applied to the crankshaft 178 to cancel the excitation force Fr may be evenly distributed to the two CS eccentric weights 182. Similarly, the weight “mr / 2” may be evenly distributed over the entire balance shaft 180 with respect to the balance shaft 180.

  In the above-described eighth embodiment, the configuration for canceling the excitation force Fr caused by the connecting rod 36 is incorporated in the balance device of the first embodiment, but the present invention is not limited to this. is not. That is, the configuration for canceling the excitation force Fr can be incorporated in any of Embodiments 2 to 7.

  In the above-described eighth embodiment, the weight for canceling the excitation force Fr caused by the connecting rod 36 is equally reflected in the CS eccentric weight 182 and the BS eccentric weight 184. It is not limited to. That is, the weight for canceling the excitation force Fr may be reflected unevenly on the CS eccentric weight 182 and the BS eccentric weight 184. This also applies to Embodiment 9 described later.

Embodiment 9 FIG.
Next, a ninth embodiment of the present invention will be described with reference to FIGS.
FIG. 46 shows the configuration of an internal combustion engine equipped with the balance device 202 according to the ninth embodiment of the present invention. The balance device 202 includes a crankshaft 204 and a balance shaft 206. The crankshaft 204 and the balance shaft 206 have a CS eccentric weight 208 and a BS eccentric weight 210, respectively. The balance device 202 of the present embodiment is the same as the balance device 170 (see FIG. 39) of the eighth embodiment except for the following two points.
(1) The CS connection point 32 is provided on the weight side of the CS eccentric weight 208 with respect to the CS main shaft 22, and the BS connection point 38 is provided on the weight side of the BS eccentric weight 210 with respect to the BS support shaft 44. Points.
(2) The CS eccentric weight 208 and the BS eccentric weight 210 are provided with centroids 212 and 214 at positions indicated by ● in FIG.

FIG. 47 is a view for explaining the principle by which the balance device 202 of the present embodiment cancels the excitation force generated in the internal combustion engine. The left side of FIG. 47 is a diagram showing conditions that the CS eccentric weight 208 and the BS eccentric weight 210 should satisfy in order to cancel the excitation force (Fp + Fc) caused by the piston 12 and the connecting rod 14. This condition is substantially the same as the condition described in the eighth embodiment with reference to the left column of FIG.

  Each of the two figures shown in FIG. 47 represents a state when the piston 12 reaches top dead center. In the configuration of the present embodiment, the connecting rod 36 is displaced from the upper right to the lower left in the figure in the process in which the piston 12 moves from the bottom dead center to the top dead center. Under the condition of top dead center, the displacement end on the lower left side in the figure is reached.

  The right-hand figure in FIG. 47 shows a state in which the connecting rod 36 has reached the lower left operation end in the figure in synchronization with the piston 12 reaching top dead center. In this state, the connecting rod 36 emits an excitation force Fr toward the lower left in the figure at an inclination angle of β ° with respect to the CS axis 174. In the present embodiment, in order to cancel out this excitation force Fr, the CS eccentric weight 208 and the BS eccentric weight 210 are respectively directed to the upper right in the figure corresponding to the weight of “mr / 2” under the condition of top dead center. Generate excitation force.

  47, the CS eccentric weight 208 and the BS eccentric weight 210 each generate an excitation force corresponding to the weight “mr / 2”. Those excitation forces are directed to the upper right in the figure at an angle of β ° with respect to the CS axis 174 and the BS axis 176. According to these excitation forces, the excitation force Fr caused by the connecting rod 36 can be canceled properly.

  When the piston 12 reaches the bottom dead center, the connecting rod 36 reaches the displacement end on the upper right side in the figure, and generates an excitation force Fr corresponding to the weight mr in the right receiving direction. At this time, the CS eccentric weight 208 and the BS eccentric weight 210 generate an excitation force in the lower left direction in the drawing. For this reason, according to said setting, the excitation force resulting from the connection rod 36 can be negated also at a bottom dead center.

  Between the top dead center and the bottom dead center, the connecting rod 36 does not generate a large excitation force. On the other hand, the weight “mr / 2” applied to the CS eccentric weight 208 and the weight “mr / 2” applied to the BS eccentric weight 210 cancel each other's excitation force while rotating in opposite directions.

  As described above, when the CS eccentric weight 208 and the BS eccentric weight 210 satisfy the conditions shown on the right side of FIG. 47, the excitation force accompanying the movement of the connecting rod 36 is always canceled by the CS eccentric weight 208 and the BS eccentric weight 210. be able to.

  In the present embodiment, the conditions shown on the left side and the conditions shown on the right side of FIG. 47 are combined and imposed on the CS eccentric weight 208 and the BS eccentric weight 210, respectively. Specifically, the CS eccentric weight 208 and the BS eccentric weight 210 are given a weight and a center of gravity that satisfy the following conditions, respectively.

<CS eccentric weight>
When the piston 12 reaches top dead center, an excitation force is generated by combining two excitation forces having the following magnitudes and directions.
(1) Size: corresponding to weight (mc + mp / 2) Direction: anti-Fp direction (2) Size: corresponding to weight (mr / 2) Direction: anti-Fr direction

<BS eccentric weight>
When the piston 12 reaches top dead center, an excitation force is generated by combining two excitation forces having the following magnitudes and directions.
(1) Size: corresponding to weight (mp / 2) Direction: anti-Fp direction (2) Size: corresponding to weight (mr / 2) Direction: anti-Fr direction

  FIG. 48 is an enlarged view of the crankshaft 204 shown in FIG. 46, that is, the crankshaft 204 used in this embodiment. The crankshaft 204 has a weight and a center of gravity that satisfy the above conditions. Specifically, the crankshaft 204 has a weight of approximately (mc + mp / 2−mr / 2), and has a center of gravity 212 at a position indicated by a point ● in FIG.

  If the crankshaft 204 cancels only the excitation force (Fp + Fc) caused by the piston 12 and the connecting rod 14, it is desirable that the position of the center of gravity 212 at the top dead center overlaps the CS axis 174. On the other hand, in the present embodiment, the position of the center of gravity 212 is shifted from the CS axis 174 to the side opposite to the Fr direction by βcs ° in order to cancel the excitation force Fr caused by the connecting rod 36. That is, the crankshaft 204 of the present embodiment has a center of gravity 212 on the opposite side of the CS connection point 32 with respect to the CS axis 174.

  The crankshaft 204 includes two CS eccentric weights 208 in the same manner as the crankshaft 178 shown in FIG. Also in the present embodiment, as in the case of the eighth embodiment, the weight “Fr / 2” for canceling the excitation force Fr caused by the connecting rod 36 is equal to the CS eccentric weight 208 arranged near the connecting rod 36. Only reflected in. Specifically, half of the weight “mc + mp / 2” for canceling the excitation force (Fp + Fc) is given to the CS eccentric weight 208 arranged at a position away from the connecting rod 36. On the other hand, the CS eccentric weight 208 disposed near the connecting rod 36 has a weight “(mc + mp / 2) / 2−mr / 2” obtained by subtracting the weight “mr / 2” for canceling the excitation force Fr. Is given. The latter CS eccentric weight 208 is formed such that the center of gravity of the two CS eccentric weights 208 is the center of gravity 212 shown in FIG. According to such a configuration, the excitation force Fr caused by the connecting rod 36 can be canceled without applying a large moment to the crankshaft 204 as in the case of the eighth embodiment.

  FIG. 49 is an enlarged view of the balance shaft 206 shown in FIG. 46, that is, the balance shaft 206 used in the present embodiment. The BS eccentric weight 201 of the balance shaft 206 is provided with a small diameter portion 216 and a large diameter portion 218. The small diameter portion 216 is formed in the vicinity of one end 194 on the side connected to the connecting rod 36. The large diameter portion 218 is formed in the vicinity of the other end 196 of the balance shaft 206.

  The BS eccentric weight 210 is generally given a weight of “mp / 2−mr / 2”. Of this weight, the weight “mp / 2” is equally distributed to the small diameter portion 216 and the large diameter portion 218. The weight reduction “mr / 2” is reflected only in the small diameter portion 216. The center of gravity 214 of the BS eccentric weight 210 is provided on the opposite side of the BS connection point 38 across the BS axis 176, as in the case of the crankshaft 204 (see FIG. 46). According to such setting, the excitation force Fr caused by the connecting rod 36 can be canceled without applying a large moment to the balance shaft 206.

  FIG. 50 is a view for explaining the operation of the internal combustion engine equipped with the balance device 202 of the present embodiment. Specifically, FIG. 50 shows the state of the internal combustion engine in increments of 45 [° CA] from 0 [° CA] to 360 [° CA]. In the figure, the excitation force generated by the CS eccentric weight 208 is represented by Fcs and (−Fcs). “Fcs” is a virtual excitation force corresponding to the weight “mc + mp / 2”, and “−Fcs” is a virtual negative excitation force generated by the weight loss “−mr / 2”. Actually, the CS eccentric weight 208 generates an excitation force corresponding to a combined vector of the vector “Fcs” and the vector “−Fcs”.

  Similarly, in FIG. 50, the excitation force generated by the BS eccentric weight 210 is represented by Fbs and (−Fbs). “Fbs” is a virtual excitation force corresponding to the weight “mp / 2”, and “−Fbs” is a virtual negative excitation force generated by the weight loss “−mr / 2”. Actually, the BS eccentric weight 210 generates an excitation force corresponding to a combined vector of the vector of “Fbs” and the vector of “−Fbs”.

  As shown in FIG. 50, according to the configuration of the present embodiment, the excitation force (Fp + Fc) caused by the piston 12 and the connecting rod 14 is the excitation force (Fcs + Fbs) caused by the CS eccentric weight 208 and the BS eccentric weight 210. Has been countered by. Further, the excitation force Fr caused by the connecting rod 36 is canceled by the effect of reducing the amount of the CS eccentric weight 208 and the BS eccentric weight 210 (-Fcs-Fbs). For this reason, according to the structure of this embodiment, the excitation force accompanying the action | operation of an internal combustion engine can always be canceled appropriately.

[Modification of Embodiment 9]
FIG. 51 is a perspective view of another example of a balance shaft applicable to the balance device 202 of the present embodiment. A balance shaft 220 shown in FIG. 51 has a BS eccentric weight 222. The BS eccentric weight 222 is formed so that the outer diameter gradually increases from one end 194 to the other end 196 on the side connected to the connecting rod 36. According to such a configuration, as in the case of the balance shaft 206 shown in FIG. 49, the weight mr for canceling the excitation force Fr caused by the connecting rod 36 is applied to the one end 194 side and the other end 196 side. In comparison, it can be reflected greatly. Therefore, even with the balance shaft 220 shown in FIG. 51, the excitation force Fr can be canceled without causing a large moment.

  By the way, in the above-described ninth embodiment, the weight for canceling the excitation force Fr caused by the connecting rod 36 is largely reflected on the side closer to the connecting rod 36. However, this feature is not essential to the present invention. That is, the weight “mr / 2” reduced from the crankshaft 204 to cancel the excitation force Fr may be equally reduced from the two CS eccentric weights 208. Similarly, the weight “mr / 2” of the balance shaft 206 may be equally reduced from the entire area of the balance shaft 206.

  In the above-described ninth embodiment, the configuration for canceling the excitation force Fr caused by the connecting rod 36 is incorporated in the balance device based on the first embodiment, but the present invention is limited to this. Is not to be done. That is, the configuration for canceling the excitation force Fr can be incorporated into a balance device based on any one of the second to seventh embodiments.

Embodiment 10 FIG.
[Configuration of Embodiment 10]
Next, a tenth embodiment of the present invention will be described with reference to FIGS.
The balance device 30 (see FIG. 1) of the first embodiment described above is configured such that the BS connection point 38 can slide in the radial direction of the balance shaft 40. Hereinafter, this method is referred to as “slide type”. Among the balance devices disclosed in this specification, in addition to the balance device of the first embodiment, the second embodiment (see FIG. 14), the sixth embodiment (see FIG. 28), and the seventh embodiment (FIG. 35). The balance device of the eighth embodiment (see FIG. 39) and the ninth embodiment (see FIG. 46) is a slide type.

  On the other hand, the balance device 78 of the above-described third embodiment is connected to the balance shaft 80 so that the BS connection point 38 can only be relatively rotated. Hereinafter, this method is referred to as “link type”. Among the balance devices disclosed in this specification, in addition to the balance device of the third embodiment, the balance devices of the fourth embodiment (see FIG. 19) and the fifth embodiment (see FIG. 25) are linked. is there.

  FIG. 52 is an exploded perspective view of the balance device 224 according to the tenth embodiment of the present invention. The balance device 224 of the present embodiment is characterized in that it provides an example of a specific configuration that realizes the link-type balance device described above.

  The balance device 224 includes a crankshaft 226. The crankshaft 226 is provided with a crankpin 228. The crankpin 228 is connected to a piston (not shown) of the internal combustion engine via a connecting rod (not shown). CS eccentric weights 230 are provided on both sides of the crankpin 228. In addition, the crankshaft 226 includes a CS main shaft 232 as a rotation shaft thereof.

  The balance device 224 includes a CS-side eccentric shaft 234 that is fixed to the CS main shaft 232. The CS-side eccentric shaft 234 is provided with a through hole 236 that fits into the CS main shaft 232. The through hole 236 is provided at a position eccentric from the center of the CS-side eccentric shaft 234 by a certain value. A positioning groove 238 is provided in the through hole 236. The CS-side eccentric shaft 234 is attached to the CS main shaft 232 such that the positioning guide 240 of the CS main shaft 232 is engaged with the positioning groove 238. As a result, the CS-side eccentric shaft 234 is fixed to the CS main shaft 232 in a state where relative rotation is not allowed. The CS-side eccentric shaft 234 is further provided with a plurality of reduction holes 242 at positions that do not interfere with the through holes 236.

  The balance device 224 includes a balance shaft 244. The balance shaft 244 includes a BS eccentric weight 246. The balance shaft 244 includes a BS support shaft 248 parallel to the CS main shaft 232. The balance shaft 244 can rotate about the BS support shaft 248 as a rotation shaft.

  A BS-side eccentric shaft 250 is attached to the BS support shaft 248. The BS-side eccentric shaft 250 is provided with a through hole 252 that fits into the BS support shaft 248. The through hole 252 is provided at a position eccentric from the center of the BS side eccentric shaft 250 by a certain value. Similarly to the CS-side eccentric shaft 234, the BS-side eccentric shaft 250 is also fixed to the BS support shaft 248 in a state where relative rotation is not allowed. The BS side eccentric shaft 250 is further provided with a plurality of reduction holes 254 at positions that do not interfere with the through holes 252.

The balance device 224 includes a connecting rod 256.
FIG. 53 is an exploded perspective view of the connecting rod 256. As shown in FIG. 53, the connecting rod 256 includes a connecting rod main body 258. The connecting rod main body 258 includes a CS-side annular portion 260 and a BS-side annular portion 262. The CS-side annular part 260 and the BS-side annular part 262 are integrated by a connecting part 264.

  After the CS-side bearing 266 is accommodated in the CS-side annular portion 260, a retaining ring 268 is attached. The retaining ring 268 prevents the CS side bearing 266 from falling off. Similarly, after the BS side bearing 270 is accommodated in the BS side annular portion 262, the retaining ring 272 is attached. The retaining ring 272 prevents the BS side bearing 270 from falling off. The CS side bearing 266 and the BS side bearing 270 are rolling bearings each including a plurality of bearing balls.

  A pivot 274 is attached to the connecting portion 264 of the connecting rod 256. The pivot 274 can function as a rolling bearing. The pivot 274 is fixed by a nut 276 disposed on the opposite side across the connecting portion 264.

  The description will be continued with reference to FIG. The CS-side eccentric shaft 234 described above is inserted into the CS-side bearing 266. As a result, the CS-side eccentric shaft 234 is rotatably held by the connecting rod 256. Similarly, the BS side eccentric shaft 250 described above is inserted into the BS side bearing 270. As a result, the BS side eccentric shaft 250 is rotatably held by the connecting rod 256.

  The balance device 224 includes a guide part 278. The guide portion 278 has a long hole 280 therein. The guide portion 278 is fixed at a predetermined position so that the pivot 274 is accommodated in the elongated hole 280. The elongated hole 280 has a width slightly larger than the diameter of the pivot 274, and guides the operation of the pivot 274 so as to draw an 8-shaped path, like the guide portion 82 in the third embodiment.

FIG. 54 is a side sectional view of the balance device 224 of the present embodiment. 54, a cross section of the balance shaft 244 is drawn upward, and a cross section of the crankshaft 226 is drawn downward. In an internal combustion engine, the crank shaft 226 functions as a drive source of the timing chain Yao Iruponpu for driving the intake and exhaust valves. Here, as an example, a state where a sprocket 282 is provided on the CS main shaft 232 and a timing chain 284 is installed on the sprocket 282 is shown.

  As shown in FIG. 54, a CS-side eccentric shaft 234 is attached to the tip of the CS main shaft 232 by a set bolt 286. Hereinafter, the center point of the CS main shaft 232 is referred to as “C232”, and the center point of the CS-side eccentric shaft 234 is referred to as “C234”. In the present embodiment, an eccentric amount A is secured between the point C232 and the point C234.

  As described above, the CS main shaft 232 is fixed to the CS-side eccentric shaft 234 so that relative rotation does not occur. For this reason, when the CS main shaft 232 rotates, the CS-side eccentric shaft 234 rotates together with the CS main shaft 232 while maintaining the eccentric amount A. At this time, the point C234 draws a circular orbit with a radius A centered on the point C232.

  The CS side eccentric shaft 234 is rotatably held inside the connecting rod 256. For this reason, the connecting rod 256 can rotate around the CS-side eccentric shaft 234 about the point C234. The CS side eccentric shaft 234 is integrated with the crankshaft 226. Therefore, the connecting rod 256 and the crankshaft 226 are relatively rotatable around the point C234. In this respect, the center point C234 of the CS-side eccentric shaft 234 corresponds to the CS connection point 32 in the third embodiment described above.

  When the CS main shaft 232 rotates 90 [° CA] from the state shown in FIG. 54, the point of C234 is lowered to the same height as the point of C232. During this time, the connecting rod 256 moves by a distance A in the downward direction in the figure. When the CS main shaft 232 further rotates 90 [° CA], the point C234 moves to a point separated by a distance A below the point C232. During this time, the connecting rod 256 further strokes by the distance A and reaches the displacement end on the lower side in the figure. Thus, according to the configuration of the present embodiment, it is possible to cause the connecting rod 256 to reciprocate with a stroke distance of 2A as the crankshaft 226 rotates.

  By the way, in this embodiment, the CS main shaft 232 has a radius B. For this reason, the distance from the center point C234 of the CS-side eccentric shaft 234 to the outer periphery of the CS main shaft 232 is “A + B” at the maximum. In this embodiment, the diameter D is set to a sufficiently large value so that the distance A + B is sufficiently within the radius (D / 2) of the CS-side eccentric shaft 234. For this reason, according to the present embodiment, the through hole 236 (see FIG. 52) that can accommodate the entire diameter of the CS main shaft 232 within the outer diameter of the CS-side eccentric shaft 234 is ensured without impairing the desired strength. can do.

  As shown in the upper part of FIG. 54, a BS side eccentric shaft 250 is attached to the tip of the BS support shaft 248 by a set bolt 288. Hereinafter, the center point of the BS support shaft 248 is referred to as “C248”, and the center point of the BS side eccentric shaft 250 is referred to as “C250”. In the present embodiment, an eccentricity amount A is secured between the point C248 and the point C250, similarly to the CS main shaft 232 side.

  When the crankshaft 226 rotates from the state shown in FIG. 54 so that the center point C234 of the CS-side eccentric shaft 234 rotates toward the front side of the page around the point of C232, the guide portion 278 becomes the guide in the third embodiment. Functions in the same manner as the unit 82. Specifically, at this time, the guide portion 278 does not allow the pivot 274 to be displaced toward the front side of the paper, and restricts the movement only to the movement toward the back side of the paper. As a result, the connecting rod 256 moves to displace the BS side eccentric shaft 250 to the back side of the drawing.

  The operation of the BS side eccentric shaft 250 is restricted by the connecting rod 256 and the BS support shaft 248. On the other hand, the BS side eccentric shaft 250 can rotate inside the connecting rod 256. According to the restraint of the connecting rod 256, the BS side eccentric shaft 250 needs to be simultaneously displaced downward in the drawing in order to be displaced from the state shown in FIG. Further, since the point C248 is fixed by the BS support shaft 248, the above displacement must occur while the distance between the point C250 and C248 is maintained at the eccentric amount A.

  If the rotation of the crankshaft 226 is continued from the state shown in FIG. 54 under such constraint conditions, the BS-side eccentric shaft 250 draws a circular orbit having a radius A with the center point C250 as the center at the point C248. Thus, the operation of revolving around the BS support shaft 248 is shown. The BS-side eccentric shaft 250 is fixed to the BS support shaft 248 so as not to rotate relatively as described above. For this reason, the rotation of the BS side eccentric shaft 250 is transmitted to the BS support shaft 248 as it is.

  In the configuration of the present embodiment, the connecting rod 256 can rotate relative to the BS-side eccentric shaft 250 with an axis passing through the point of C250 as a rotation axis. The BS side eccentric shaft 250 is integrated with the balance shaft 244. Therefore, the connecting rod 256 and the balance shaft 244 are relatively rotatable around the point C250. In this respect, the center point C250 of the BS side eccentric shaft 250 corresponds to the BS connection point 38 in the link type balance device (see FIG. 15).

While the BS side eccentric shaft 250 revolves around the BS support shaft 248 once, the point of C250 indicates a reciprocating motion with a stroke distance of 2A. During this time, the connecting rod 256 similarly exhibits a reciprocating motion with a stroke distance of 2A. Then, the reciprocating motion is performed in synchronization with the raw sly reciprocate side of CS main shaft 232. As a result, according to the configuration of the present embodiment, the operation and function described in the third embodiment can be realized.

  By the way, in this embodiment, the BS support shaft 248 has a radius E. For this reason, the distance from the center point C250 of the BS side eccentric shaft 250 to the outer periphery of the BS support shaft 248 is “A + E” at the maximum. In this embodiment, the diameter F is set to a sufficiently large value so that the distance A + E is sufficiently within the radius (F / 2) of the BS side eccentric shaft 250. Therefore, according to the present embodiment, the through hole 252 (see FIG. 52) that can accommodate the entire diameter of the BS support shaft 248 within the outer diameter of the BS side eccentric shaft 250 without impairing the desired strength. Can be secured.

[Processing method for CS side eccentric shaft and BS side eccentric shaft]
FIG. 55 is a diagram for explaining a method of forming the CS-side eccentric shaft 234 and the BS-side eccentric shaft 250 in this embodiment by co-drilling. As described above, in the balance device 224 of the present embodiment, the eccentric amount between the CS main shaft 232 and the CS side eccentric shaft 234 and the eccentric amount between the BS support shaft 248 and the BS side eccentric shaft 250 are the same amount “A”. Is set.

As described in the third embodiment, in the link type balance device, the rotation radius r1 of the CS connection point and the rotation radius r2 of the BS connection point must be the same value. In the present embodiment, the CS connection point is C234, and the rotation radius r1 corresponds to the eccentric amount A. Similarly, the BS connection point is C 250, and the rotation radius r 2 is the eccentric amount A. Therefore, in this embodiment, it is necessary to accurately match the eccentricity A on the CS main shaft 232 side with the eccentricity A on the BS support shaft 248 side.

FIG. 55 specifically shows a state where the BS-side eccentric shaft 250 and the CS-side eccentric shaft 234 are set in the same jig 290. Jig 290 has a two-step recess 292, 294 about the axis indicating subjected to C234, C 250 in FIG. The recess 292 is formed in a circular shape having a diameter equal to the diameter of the CS side eccentric shaft 234. The recess 294 is formed in a circular shape having a diameter equal to the diameter of the BS side eccentric shaft 250. These depressions 292 and 294 are processed to be concentric.

  In the present embodiment, the BS side eccentric shaft 250 at the stage where the processing of the outer shape and the reduction hole 242 is finished is first set in the recess 294 of the jig 290. Next, the CS-side eccentric shaft 234 at the stage where the processing of the outer shape and the reduction hole 254 is finished is set in the recess 292 of the jig 290. Thereafter, the through-hole 252 of the BS-side eccentric shaft 250 and the through-hole 236 of the CS-side eccentric shaft 234 are sequentially provided by a co-drilling technique. According to such a method, the eccentric amount A of the CS-side eccentric shaft 234 and the eccentric amount A of the BS-side eccentric shaft 250 can be exactly matched.

[Effects of reduced holes]
FIG. 56 is a front view of an internal combustion engine including the balance device 224 of the present embodiment. More specifically, the left side of FIG. 56 represents a state where the piston 12 is located at the top dead center. Also, the right side of FIG. 56 represents a state where the piston 12 is located at the bottom dead center.

  In the balance device 224 of this embodiment, when the piston 12 reaches the top dead center, the connecting rod 256 reaches the displacement end on the upper right side in the drawing, and when the piston 12 reaches the bottom dead center, the connecting rod 256 moves to the lower left side in the drawing. It is configured to reach the displacement end on the side. In other words, the balance device 224 of the present embodiment has a configuration in which the CS eccentric weight 230 and the BS eccentric weight 246 are operated in a direction generally opposite to the connecting rod 256.

  In the balance device having such a configuration, it is necessary to add the weight mr of the connecting rod 256 to the CS eccentric weight 230 and the BS eccentric weight 246 in order to cancel the excitation force Fr caused by the connecting rod 256. For this reason, from the viewpoint of reducing the weight of the internal combustion engine, the connecting rod 256 is preferably as light as possible. In this sense, it is preferable that the CS-side eccentric shaft 234 and the BS-side eccentric shaft 250 that are displaced integrally with the connecting rod 256 are lighter.

  Further, in the balance device 224 of the present embodiment, in synchronization with the timing when the connecting rod 256 reaches the displacement end on the upper right side in the figure, the wide part of the CS side eccentric shaft 234 (the part in which the reduction hole 242 is drilled), and The wide part of the BS side eccentric shaft 250 (the part in which the reduction hole 254 is formed) rotates in the direction of the displacement end. For this reason, if those wide portions have a large weight, a large excitation force is generated due to the centrifugal force of the CS-side eccentric shaft 234 itself and the centrifugal force of the BS-side eccentric shaft 250 itself. For this reason, a reduction in weight is particularly desired for the wide portion of the CS-side eccentric shaft 234 and the wide portion of the BS-side eccentric shaft 250.

  As shown in FIG. 56, in the present embodiment, lightening holes 242 and 254 are provided in these wide portions. According to these reduction holes 242 and 254, the weight of the wide portion can be greatly reduced. As a result, the excitation force resulting from the centrifugal force of the CS-side eccentric shaft 234 and the centrifugal force of the BS-side eccentric shaft 250 is greatly reduced. Further, the excitation force due to the weight of the connecting rod 256 is also greatly reduced. For this reason, according to the configuration of the present embodiment, it is possible to reduce the weight of the CS eccentric weight 230 and the BS eccentric weight 246, and thereby to reduce the weight of the internal combustion engine.

[Modification of Embodiment 10]
FIG. 57 is a side sectional view of a modified example of the balance device 224 of the present embodiment. As described above, the balance device 224 of the present embodiment is designed such that the diameter of the CS main shaft 232 is sufficiently within the outer shape of the CS-side eccentric shaft 234. For this reason, the CS main shaft 232 can penetrate the CS-side eccentric shaft 234 while maintaining a circular shape.

  Further, in the balance device 224 of this embodiment, the pivot 274 and the guide portion 278 are disposed on the crankshaft 226 and the balance shaft 244 side, so that the surface side (left side in FIG. 57) of the connecting rod 256 is substantially flat. It can be. For this reason, according to the balance apparatus 224, CS main shaft 232 can be protruded long from the connecting rod 256, and it can utilize for the drive of various apparatuses. FIG. 57 shows an example in which an oil pump drive shaft 296 is attached to the CS main shaft 232 in addition to 282 for driving the intake and exhaust valves. Thus, according to the balance device 224 of the present embodiment, it is possible to promote downsizing of the internal combustion engine.

  FIG. 58 is a diagram for explaining a configuration of a modified example of the BS side eccentric shaft that can be used in the present embodiment. 58 has a diameter G, that is, a radius (G / 2). The radius (G / 2) may have to be smaller than the sum of the eccentricity A and the radius E of the BS support shaft 248 due to various restrictions. The configuration shown in FIG. 58 shows an example of a solution in such a case. In this configuration, the BS side eccentric shaft 298 has a through hole smaller than the cross section of the BS support shaft 248. On the other hand, the tip of the BS support shaft 248 is processed into a shape that can be inserted into the through hole. The tip of the processed BS support shaft 248 is fixed in a state of being inserted into the through hole of the BS side eccentric shaft 298. According to such a configuration, even when a sufficiently large space cannot be secured for the BS-side eccentric shaft 298, a balance device using the connecting rod 256 can be realized.

  FIG. 59 is a diagram for explaining a configuration of a modified example of the CS-side eccentric shaft that can be used in the present embodiment. The CS-side eccentric shaft 300 shown in FIG. 59 has a diameter H, that is, a radius (H / 2). The radius (H / 2) may have to be smaller than the sum of the eccentricity A and the radius B of the CS main shaft 232 due to various restrictions. The configuration shown in FIG. 59 shows an example of a solution in such a case. In this configuration, the CS-side eccentric shaft 300 has a through hole smaller than the cross section of the CS main shaft 232. On the other hand, the tip of the CS main shaft 232 is processed into a shape that can be inserted into the through hole. The set bolt 288 is tightened in a state where the tip of the processed CS main shaft 232 is inserted into the through hole of the CS-side eccentric shaft 300. According to such a configuration, even when a sufficiently large space cannot be secured for the CS-side eccentric shaft 300, a balance device using the connection rod 256 can be realized.

  FIG. 60 is a front view of a modification of the balance device of the present embodiment. Specifically, the left side of FIG. 60 represents a state where the piston 12 is located at the top dead center in the modification. Further, the right side of FIG. 60 represents a state in which the piston 12 is located at the bottom dead center in the modified example.

In the balance device 302 shown in FIG. 60, when the piston 12 reaches the top dead center, the connecting rod 256 reaches the lower left displacement end in the drawing, and when the piston 12 reaches the bottom dead center, the connecting rod 256 moves to the upper right corner in the drawing. It is configured to reach the displacement end on the side. That is, in the balance device 302, the CS eccentric weight 230 and the BS eccentric weight 246 operate in substantially the same direction as the connecting rod 256.

  In the balance device having such a configuration, the excitation force Fr caused by the connecting rod 256 can be used as a force for canceling the excitation force Fp + Fc caused by the piston 12 and the connecting rod 14. And the weight which should be given to CS eccentric weight 230 and BS eccentric weight 246 can be made light, so that the excitation force Fr is large.

  Unlike the CS-side eccentric shaft 234 in the tenth embodiment, the CS-side eccentric shaft 304 shown in FIG. Similarly, BS side eccentric shaft 306 shown in FIG. 60 does not have a reduction hole unlike BS side eccentric shaft 250 in the tenth embodiment. According to the CS-side eccentric shaft 304 and the BS-side eccentric shaft 306, a large excitation force can be generated by its centrifugal force, and a large excitation force Fr can be generated in the connecting rod 256. it can. For this reason, the structure shown in FIG. 60 can promote weight reduction of the CS eccentric weight 230 and the BS eccentric weight 246.

  In the tenth embodiment described above, the CS-side bearing 266 and the BS-side bearing that are included in the connecting rod 256 are configured by rolling bearings. However, these bearings are not limited to rolling bearings. For example, they may be sliding bearings that use lubricating oil. This also applies to the eleventh embodiment described later.

Embodiment 11 FIG.
Next, an eleventh embodiment of the present invention will be described with reference to FIGS.
FIG. 61 is an exploded perspective view of the balance device 308 according to the eleventh embodiment of the present invention. The balance device 308 of the present embodiment is characterized in that it provides an example of a specific configuration for realizing the slide-type balance device shown in the first embodiment (see FIG. 1). In FIG. 61 to FIG. 66, the same or common elements as those of the tenth embodiment described above are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  In the balance device 308, the CS-side eccentric shaft 234 is fixed to the CS main shaft 232 as in the case of the tenth embodiment. A BS-side eccentric shaft 310 is fixed to the BS support shaft 248. The BS-side eccentric shaft 310 has a long hole 312 on the surface opposite to the surface fixed to the BS support shaft 248. The outer shape of the BS side eccentric shaft 310 is cylindrical, and the elongated hole 312 is provided along the radial direction of the circle.

The balance device 308 includes a connecting rod 314 that connects the CS-side eccentric shaft 234 and the BS-side eccentric shaft 310.
FIG. 62 is an exploded perspective view of the connecting rod 314. As shown in FIG. 62, the connecting rod 314 has a connecting rod main body 316. The connecting rod main body 316 has a columnar portion 318 extending from the CS-side annular portion 260. A BS pivot 322 is fixed to the end of the columnar portion 318 by a nut 320. A pivot 274 is fixed to the columnar portion 318 by a nut 276 near the boundary with the CS-side annular portion 260. The BS pivot 322 functions as a rolling bearing like the pivot 274.

  The description will be continued with reference to FIG. The CS-side eccentric shaft 234 described above is inserted into the CS-side bearing 266 of the connecting rod 314 as in the case of the tenth embodiment. On the other hand, the BS side eccentric shaft 310 is connected to the connecting rod 314 by accommodating the BS pivot 322 in the elongated hole 312.

  The balance device 308 includes a guide part 324. The guide portion 324 has a long hole 326 inside thereof. The long hole 326 has a width that matches the diameter of the pivot 274, and restricts the movement of the pivot 274 to a linear movement, like the guide portion 54 in the first embodiment.

  FIG. 63 is a side sectional view of the balance device 308 of the present embodiment. 63, the cross section of the balance shaft 244 is drawn upward, and the cross section of the crankshaft 226 is drawn downward. The crankshaft 226 is provided with a sprocket 282 that drives the timing chain 284 as in the tenth embodiment.

  In the configuration shown in FIG. 63, CS-side eccentric shaft 234 operates in the same manner as in the tenth embodiment. Specifically, also in this embodiment, the center point “C234” of the CS-side eccentric shaft 234 corresponds to the CS connection point 32 of the balance device. When the crankshaft 226 rotates, the CS connection point 32 (C234) draws a circular orbit around the center point C232 of the CS main shaft while maintaining the eccentricity A. Accordingly, the connecting rod 314 reciprocates with a stroke of distance 2A.

  Also in the present embodiment, the radius (D / 2) of the CS-side eccentric shaft 234 is set to a sufficiently large value with respect to the sum of the eccentric amount A and the radius B of the CS main shaft 232. For this reason, it is possible to apply the packaging suitable for miniaturization as shown in FIG. 57 also in the structure of this embodiment.

  As shown in the upper part of FIG. 63, the BS side eccentric shaft 310 is fixed to the tip of the BS support shaft 248 by a set bolt 328. The BS pivot 322 of the connecting rod 314 is accommodated in the elongated hole 312 of the BS side eccentric shaft 310. Hereinafter, the center point of the BS support shaft 248 is referred to as “C248”, and the center point of the BS pivot 322 is referred to as “C322”.

In the configuration of the present embodiment, the connecting rod 314 can rotate relative to the BS side eccentric shaft 310 with the axis passing through the point of C322 as a rotation axis. The BS side eccentric shaft 310 is integrated with the balance shaft 244. Therefore, the connecting rod 314 and the balance shaft 244 are relatively rotatable around the point of C322. In this respect, the center point C 322 of the BS pivot 322 corresponds to the BS connection point 38 in the sliding balance device (see FIG. 2).

  As described with reference to FIG. 2, in the sliding balance device 30, the distance between the BS connection point 38 and the center point of the balance shaft 40 changes with the operation of the connection rod 36. Since the balance device 308 of the present embodiment is also a slide type, the distance between the BS connection point 38 and the center point of the balance shaft 244, that is, the distance between the center point C322 of the BS pivot 322 and the center point C248 of the BS support shaft 248. Must be changeable.

  FIG. 64 is a diagram showing the positional relationship between the center point C248 of the BS support shaft 248 and the center point C322 of the BS pivot 322 as viewed in the direction of the arrow LXIV shown in FIG. As shown in FIG. 64, according to the configuration of the present embodiment, the eccentric amount I of C322 with respect to C248 changes as the BS pivot 322 slides along the elongated hole 312. For this reason, according to the configuration of the BS side eccentric shaft 310 and the connecting rod 314 in the present embodiment, it is possible to satisfy the requirements necessary for the operation of the sliding balance device.

  The operation of the balance device 308 will be described with reference to FIG. 63 again. 63, when the crankshaft 226 is rotated so that the center point C234 of the CS-side eccentric shaft 234 rotates toward the front side of the paper with respect to the point of C232, the guide portion 324 becomes the guide in the first embodiment. It functions in the same way as the unit 54. Specifically, at this time, the guide portion 324 does not allow the pivot 274 to be displaced toward the front side of the paper, and restricts the movement only to the downward movement of the paper. As a result, the connecting rod 314 moves so as to displace the BS pivot 322 toward the back side of the drawing.

  This movement of the BS pivot 322 gives the BS side eccentric shaft 310 a rotation opposite to the rotation of the crankshaft 226. Since the BS side eccentric shaft 310 is fixed to the BS support shaft 248, a rotational motion is generated in the BS support shaft 248 in accordance with the displacement of the BS pivot 322. Thereafter, when the rotation of the crankshaft 226 continues, the center point C322 of the BS pivot 322 rotates around the C248, and the balance shaft 244 is continuously rotated. At this time, the connecting rod 314 moves up and down with the distance 2A as the stroke length.

[Effects of reduced holes]
FIG. 65 is a front view of an internal combustion engine including the balance device 308 of the present embodiment. More specifically, the left side of FIG. 65 represents a state where the piston 12 is located at the top dead center. Further, the right side of FIG. 65 represents a state where the piston 12 is located at the bottom dead center.

  As in the case of the tenth embodiment, the balance device 308 of the present embodiment has a configuration in which the CS eccentric weight 230 and the BS eccentric weight 246 are operated in a direction generally opposite to the connecting rod 314. In the balance device having such a configuration, it is preferable that the connecting rod 314 is lighter from the viewpoint of reducing the weight of the internal combustion engine. In the present embodiment, a reduction hole 242 is provided in the wide portion of the CS-side eccentric shaft 234 as in the case of the tenth embodiment. For this reason, also with the configuration of the present embodiment, the internal combustion engine can be reduced in weight as in the case of the tenth embodiment.

[Modification of Embodiment 11]
As described above, in the eleventh embodiment, the CS-side eccentric shaft 234 is given a radius (D / 2) sufficiently larger than the sum of the eccentric amount A and the radius B of the CS main shaft 232. However, the radius (D / 2) of the CS main shaft 232 may be inevitably smaller than A + B due to various restrictions. Also in the balance device 308 of the present embodiment, in such a case, a configuration as shown in FIG. 59 may be adopted as in the case of the tenth embodiment.

FIG. 66 is a front view of a modified example of the balance device of the present embodiment. Specifically, the left side of FIG. 66 represents a state where the piston 12 is located at the top dead center in the modification. Further, the right side of FIG. 66 represents a state in which the piston 12 is located at the bottom dead center in the modified example. In the balance device 330 shown in FIG. 66, unlike the case of the eleventh embodiment, the CS eccentric weight 230 and the BS eccentric weight 246 operate in substantially the same direction as the connecting rod 314.

  In the balance device 330 having such a configuration, the weight of the connecting rod 314 can be used to cancel the excitation force Fr caused by the piston 12 and the connecting rod 14. For this reason, in the balance device 330, the weight to be given to the CS eccentric weight 230 and the BS eccentric weight 246 can be reduced by leaving a large weight in the connecting rod 314. For this reason, in the configuration shown in FIG. 66, unlike the case of the eleventh embodiment, no reduction hole is provided in the CS-side eccentric shaft. According to such a configuration, the CS eccentric weight 230 and the BS eccentric weight 246 can be reduced in weight.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Piston 16,178,204,226 Crankshaft 18,228 Crankpin 20 Crank arm 22,232 CS main shaft 24,182,208,230 CS eccentric weight 30,66,78,140,154,156,156 , 168, 170, 202, 224, 302, 308, 330 Balance device 32 CS connection point 34 CS connection mechanism 36, 256, 314 Connection rod 38 BS connection point 40, 80, 180, 198, 206, 220, 244 Balance shaft 42 BS connection mechanism 44, 248 BS support shaft 46 BS connection point adjustment mechanism 48, 184, 200, 210, 222, 246 BS eccentric weight 50, 274 Pivot 52 Sliding part 54, 68, 82, 278, 324 Guide part 56 CS-BS center line 72 Rotating shaft 90 BS side guide 2 CS side guides 98, 120 Moment applying mechanism 100, 114 Cam 102; 104 Spring member 116; 118 Cam mechanism 122 First spring member 128 Second spring member 152 Axis 172 Axis 174 of piston reciprocating motion CS axis 176 BS axis 186 , 188, 212, 214 Center of gravity 190, 218 Large diameter portion 192, 216 Small diameter portion 194 One end 196 Other end 234, 300, 304 CS side eccentric shaft 242, 254 Reduction hole 250, 298, 306, 310 BS side eccentric shaft 266 CS Side bearing 270 BS side bearing 322 BS pivot

Claims (20)

A balance device for an internal combustion engine,
A crankshaft rotating about the CS main shaft as a rotation axis;
A balance shaft that rotates using a BS support shaft parallel to the CS main shaft as a rotation shaft,
The crankshaft includes a CS eccentric weight that decenters the center of gravity of the crankshaft from the center of the CS main shaft,
The balance shaft includes a BS eccentric weight that decenters the center of gravity of the balance shaft from the center of the BS support shaft, and
A connection for connecting a CS connection point provided at a position off the center of the CS main shaft of the crankshaft and a BS connection point provided at a position off the center of the BS support shaft of the balance shaft.桿,
A CS coupling mechanism that enables relative rotation of the crankshaft and the coupling rod with the CS coupling point as a rotation center;
A BS connection mechanism that enables relative rotation between the balance shaft and the connection rod with the BS connection point as a rotation center;
A guide portion for guiding the movement of the connecting rod so that the balance shaft rotates in reverse with the crankshaft ,
The guide portion, the sliding of the sliding portion or the connecting rod to the connecting rod comprises, balancing device for an internal combustion engine, it characterized that you achieve the guide. A connection point adjustment mechanism that enables displacement of at least one of the CS connection point and the BS connection point in the direction of the respective rotation radius;
A sliding portion provided at one point of the connecting rod,
The said guide part restrict | limits the movement of the said sliding part to the linear motion which goes to the said BS support shaft side from the said CS main axis | shaft side, and its reverse linear motion. A balance device for an internal combustion engine. A connection point adjustment mechanism that enables displacement of at least one of the CS connection point and the BS connection point in the direction of the respective rotation radius;
The guide portion can rotate in the same plane as the movable plane of the connecting rod around a position overlapping with the connecting rod, and can slide the connecting rod in the direction of the center line of the connecting rod. The balance device for an internal combustion engine according to claim 1, wherein the balance device is held by the engine. A restriction portion provided at a midpoint between the CS connection point and the BS connection point of the connection rod;
The distance between the CS connection point and the BS connection point is equal to the distance between the CS main shaft and the BS support shaft,
The distance between the center of the CS main shaft and the CS connection point is equal to the distance between the center of the BS support shaft and the BS connection point;
The guide portion includes a BS side guide that prevents the restricting portion from being displaced in the same rotational direction as the CS connection point at a position where the restricting portion is closest to the BS support shaft, and the restricting portion is the CS 2. The balance device for an internal combustion engine according to claim 1, further comprising a CS-side guide that prevents the restricting portion from being displaced in the same rotational direction as the CS connection point at a position closest to the main shaft. The crankshaft is used in an offset crank method in which the center of the CS main shaft is installed at a position offset from the axis of reciprocating motion of the piston by a certain value.
The balance shaft and the guide portion are arranged so that at least one of the center of the CS main shaft and the center of the BS support shaft is formed at a position offset by a certain value from the axis of the linear motion. The balance device for an internal combustion engine according to claim 2, wherein the balance device is an internal combustion engine.   6. The balance apparatus for an internal combustion engine according to claim 5, wherein a CS-BS center line connecting the center of the CS main shaft and the center of the BS support shaft is offset from the axis of the linear motion by a predetermined value. .   6. The internal combustion engine according to claim 5, wherein the center of the CS main axis is located on the axis of the linear motion, and the center of the BS support shaft is offset from the axis of the linear motion by a predetermined value. Institutional balance device. Located on the center of the linear movement of the axis of the BS supporting shaft, and the center of the CS spindle according to claim 5, characterized in that it is offset by a constant value from the axis of the linear motion A balance device for an internal combustion engine.   The center of the BS support shaft is offset from the linear motion axis to one side by a certain value, and the center of the CS main shaft is offset from the linear motion axis to the other side by a certain value. The balance device for an internal combustion engine according to claim 5. The crankshaft is used in an offset crank method in which the center of the CS main shaft is installed at a position offset from the axis of the reciprocating motion of the piston by a constant value.
4. The internal combustion engine according to claim 3, wherein the rotation center of the guide portion is offset by a predetermined value from a CS-BS center line connecting the center of the CS main shaft and the center of the BS support shaft. Balance device. The CS connection point is provided on the same side as the center of gravity of the CS eccentric weight with respect to the center of the CS main shaft, and the BS connection point is a center of gravity of the BS eccentric weight with respect to the center of the BS support shaft. The balance device for an internal combustion engine according to any one of claims 1 to 10, wherein the balance device is provided on the same side. The CS connection point is provided on the opposite side to the center of gravity of the CS eccentric weight with respect to the center of the CS main shaft, and the BS connection point is a center of gravity of the BS eccentric weight with respect to the center of the BS support shaft. The balance device for an internal combustion engine according to any one of claims 1 to 10, wherein the balance device is provided on an opposite side.   The balance device for an internal combustion engine according to any one of claims 1 to 12, further comprising a moment applying mechanism that applies a rotation moment in a direction opposite to a rotation direction of the crankshaft to the balance shaft. The moment application mechanism includes a cam mounted on the balance shaft, and a spring member that reduces by being pressed by the cam.
The cam presses the spring member in the process in which the connecting rod moves toward the BS support shaft as the balance shaft rotates, and the axis of the connecting rod overlaps the BS support shaft. 14. The balance device for an internal combustion engine according to claim 13, wherein the balance member is formed so as to receive the rotational moment in the reverse direction from the spring member.   The internal combustion engine balance device according to any one of claims 1 to 14, wherein the balance device is mounted on a single cylinder or a four-cycle two-cylinder internal combustion engine. The connecting rod is disposed so as to be inclined from the axis of reciprocation of the piston at the top dead center and the bottom dead center of the internal combustion engine,
The CS eccentric weight has a center of gravity in a region opposite to the CS connecting point across the CS axis passing through the center of the CS main shaft and parallel to the axis of the piston under the condition of the top dead center. ,
The BS eccentric weight has a center of gravity in a region opposite to the BS connection point across the BS axis parallel to the axis of the piston passing through the center of the BS support shaft under the condition of the top dead center. 16. The internal combustion engine balance device according to claim 1, wherein the balance device is an internal combustion engine. The CS eccentric weight is large enough to cancel the combined force of the excitation force caused by the connecting rod of the internal combustion engine, a part of the excitation force caused by the piston of the internal combustion engine, and a part of the excitation force caused by the connecting rod. Has a weight and center of gravity,
The BS eccentric weight has a weight and a center of gravity large enough to cancel the remainder of the excitation force caused by the piston of the internal combustion engine and the remainder of the excitation force caused by the connecting rod,
The balance device for an internal combustion engine according to claim 16, wherein the part and the remaining part are equal. The balance shaft is connected to the connecting rod at one end thereof,
Of the weight of the BS eccentric weight, the weight for canceling the remainder of the excitation force caused by the connecting rod is largely reflected in the vicinity of the one end compared to the vicinity of the other end of the balance shaft. 18. The balance device for an internal combustion engine according to claim 17, wherein the balance device is an internal combustion engine. The connecting rod has a CS side bearing on the crankshaft side,
The CS coupling mechanism has a CS side eccentric shaft rotatably held by the CS side bearing,
The CS-side eccentric shaft is fixed to the CS main shaft such that a CS eccentric point shifted from the center by a certain value coincides with the center of the CS main shaft,
The balance device for an internal combustion engine according to any one of claims 1 to 18, wherein a center of the CS-side eccentric shaft constitutes the CS connection point. The connecting rod has a BS side bearing on the balance shaft side,
The BS coupling mechanism has a BS side eccentric shaft rotatably held by the BS side bearing,
The BS side eccentric shaft is fixed to the BS support shaft such that a BS eccentric point shifted from the center by a certain value coincides with the center of the BS support shaft,
The balance apparatus for an internal combustion engine according to any one of claims 1 to 19, wherein a center of the BS side eccentric shaft constitutes the BS connection point.

Images