JP2020070881A - Crank mechanism - Google Patents

Abstract

To provide a crank mechanism which can fill a trough of torque outputted from a crankshaft.SOLUTION: A crank mechanism comprises: a crankshaft 4 for converting a reciprocal motion of a piston 2 to a rotational motion; a counter shaft 11 arranged in parallel with the crankshaft 4; a first asymmetric gear 10 arranged at the crankshaft 4; and a second asymmetric gear 12 arranged at the counter shaft 11, and engaged with the first asymmetric gear 10. The first asymmetric gear 10 and the second asymmetric gear 12 are formed so that a rotation radius of the first asymmetric gear 10 becomes minimum, and a rotation radius of the second asymmetric gear 12 becomes maximum in the vicinity of a crank angle in which torque generated at the crankshaft 4 by combustion pressure acting on the piston 2 becomes maximum, and the rotation radius of the first asymmetric gear 10 becomes maximum, and the rotation radius of the second asymmetric gear 12 becomes minimum in the vicinity of a crank angle in which the torque becomes minimum.SELECTED DRAWING: Figure 13

Description

  The present invention relates to a crank mechanism suitable for use in an internal combustion engine.

  In a 4-stroke internal combustion engine (hereinafter referred to as an engine), a piston reciprocates by sequentially repeating four strokes of intake, compression, explosion, and exhaust. The reciprocating motion of the piston is transmitted to the crankshaft via the connecting rod and converted into the rotary motion of the crankshaft to generate a rotational force. However, the rotational force is generated only by the power generated in the explosion stroke of the engine stroke. In the remaining strokes except the explosion stroke, power is transmitted by the rotational force generated in the explosion stroke of the pistons of the other cylinders and the rotational inertial force of the flywheel. Therefore, when attention is paid to one cylinder, torque required for engine output is generated in the explosion stroke, but torque is not generated in the remaining stroke, but rather negative torque is generated.

  FIG. 18 shows a general waveform of torque output from the crankshaft in an in-line four-cylinder engine. In an in-line 4-cylinder engine, the torque waveform changes at intervals of a crank angle of 180 degrees. Specifically, as shown in FIG. 18, a torque peak appears a little later than the combustion at the top dead center, the torque also decreases from the peak to the bottom dead center, and the torque is minus just before the bottom dead center. become. As a result, the torque blank zone "valley of torque" always appears at intervals of a crank angle of 180 degrees.

  The valley of torque is small in a multi-cylinder engine such as a 12-cylinder or an 8-cylinder having a short combustion interval, but is large in a 4-cylinder engine which is often used in a small displacement engine. The reason why a small displacement engine is liable to lose its load and easily stall when the engine speed is low is that the trough of the torque output from the crankshaft is large and the average torque is low. Therefore, filling the valley of the torque output from the crankshaft is one of the problems to be solved in the engine.

  The prior art documents listed below are documents showing the technical level in the technical field to which the present invention belongs.

JP, 2013-520612, A Japanese Patent Laid-Open No. 05-086892

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a crank mechanism that can fill the valley of the torque output from the crankshaft.

  A crank mechanism according to the present invention includes a crankshaft that converts a reciprocating motion of a piston into a rotary motion, a counter shaft that is arranged parallel to the crankshaft, a first asymmetric gear that is provided on the crankshaft, and a counter shaft. And a second asymmetric gear that meshes with the first asymmetric gear. The first asymmetrical gear and the second asymmetrical gear have a radius of gyration of the first asymmetrical gear (from the center of rotation of the first asymmetrical gear) in the vicinity of the crank angle at which the torque generated on the crankshaft by the combustion pressure acting on the piston becomes maximum. The distance to the contact point between the first asymmetric gear and the second asymmetric gear is minimized, and the radius of rotation of the second asymmetric gear (the contact point between the rotation center of the second asymmetric gear and the first asymmetric gear and the second asymmetric gear). Is shaped to maximize the distance. Further, the first asymmetric gear and the second asymmetric gear have a maximum radius of gyration of the first asymmetric gear near the crank angle at which the torque generated on the crankshaft due to the combustion pressure acting on the piston is minimized. The two asymmetrical gears are shaped so that the radius of gyration is minimized.

  According to the crank mechanism of the present invention, the rotation radius of the first asymmetric gear is minimized and the rotation of the second asymmetric gear is rotated near the crank angle at which the torque generated on the crankshaft is maximized by the combustion pressure acting on the piston. The maximum radius can maximize the rotational kinetic energy stored in the inertial body including the second asymmetric gear. In addition, the rotation radius of the first asymmetric gear is maximized and the rotation radius of the second asymmetric gear is minimized near the crank angle at which the torque generated on the crankshaft due to the combustion pressure acting on the piston is minimized. The rotational kinetic energy recovered from the inertial body including the second asymmetric gear is maximized in the torque valley, and the torque valley can be filled with the recovered rotational kinetic energy.

It is a figure which shows the waveform obtained by redistributing the torque of the peak part of a torque waveform to a valley part in an in-line 4-cylinder engine. It is a figure explaining energy storage using an inertial body. It is a figure which shows the magnitude relationship between the radius of gyration of the crankshaft and the radius of gyration of the inertial body suitable when energy is stored in an inertial body. It is a figure which shows the magnitude relationship between the radius of gyration of a crankshaft and the radius of gyration of an inertia body suitable for recovering energy from an inertial body. It is a figure which shows the structure of the elliptical gear (ellipse type | system | group single leaf gear) which adoption was examined in the creative process of this invention. It is a figure which shows the meshing state of two elliptical gears when storing energy in an inertial body. It is a figure which shows the meshing state of two elliptical gears at the time of recovering energy from an inertial body. It is a figure which shows the timing of energy storage in an in-line 4-cylinder engine. It is a figure which shows the timing of energy recovery in an in-line 4-cylinder engine. It is a figure which shows the shape of the asymmetric gear on the crankshaft side which concerns on embodiment of this invention. It is a figure which shows the shape of the inertial body side asymmetrical gearwheel which concerns on embodiment of this invention. It is a figure which shows the structure of the crank mechanism which concerns on embodiment of this invention. It is a figure which shows the state which two asymmetrical gears rotate. It is a figure which shows the Example at the time of providing one set of asymmetrical gears. It is a figure which shows the torque waveform obtained when one set of asymmetrical gears is provided. It is a figure which shows the Example at the time of providing two sets of asymmetrical gears. It is a figure which shows the torque waveform obtained when two sets of asymmetrical gears are provided. It is a figure which shows the torque waveform in an in-line 4-cylinder engine.

  Hereinafter, an embodiment of the present invention will be described together with examination contents in the creation process of the present invention.

  FIG. 1 is a diagram showing a waveform obtained by redistributing a torque at a peak portion of a torque waveform to a valley portion in an in-line four-cylinder engine. As shown in FIG. 1, in the process of inventing the present invention, it was examined that the peak portion of the torque that rises slightly after the combustion is saved as energy, and the saved energy is recovered in the vicinity of the valley between combustion and combustion. If the valley of the torque can be filled as shown in FIG. 1, the torque will be stable and engine stall will not easily occur at low rotation speed.

  As a method of storing and recovering energy, a method of using an inertial body that is rotatable by inertia can be considered. Here, as shown in FIG. 2, an inertial body that rotates around an axis parallel to the crankshaft is provided, and power is transmitted between the crankshaft and the inertial body via a gear. By transmitting the torque from the crankshaft to the inertial body, a part of the rotational motion energy of the crankshaft is stored as the energy of the rotational motion of the inertial body. Then, in the situation where torque is transmitted from the inertial body to the crankshaft, a part of the rotational motion energy of the inertial body is recovered as the rotational motion energy of the crankshaft.

  Here, the magnitude relationship between the preferred radius of gyration of the crankshaft and the radius of gyration of the inertial body will be considered for both the case of storing energy in the inertial body and the case of recovering energy from the inertial body. FIG. 3 shows a case where the radius of gyration of the inertial body is larger than the radius of gyration of the crankshaft, and as a specific example, the radius of gyration of the inertial body is twice the radius of gyration of the crankshaft. FIG. 4 shows a case where the radius of gyration of the inertial body is smaller than the radius of gyration of the crankshaft, and as a specific example, the radius of gyration of the inertial body is 1/2 times the radius of gyration of the crankshaft. The inverse ratio of the ratio of the radius of gyration of the crankshaft and the inertial body is the ratio of the number of revolutions (the number of revolutions per hour) of the crankshaft and the inertial body.

  The energy of the rotational motion of the rotating body increases as the rotation speed increases. Further, when transferring energy from one rotating body to another rotating body, the greater the energy of the moving source rotating body, the less the loss for driving the moving destination rotating body. Therefore, in order to store energy from the crankshaft to the inertial body, the magnitude relationship between the radius of gyration of the inertial body and the radius of gyration of the crankshaft as shown in FIG. 3 is suitable. This is because there is little loss of engine output. In this case, since the inertial body serves as a speed reducer with respect to the crankshaft, the rotational speed is halved, but twice the torque is transmitted from the crankshaft to the inertial body.

  On the other hand, in order to recover energy from the inertial body to the crankshaft, the magnitude relationship between the radius of gyration of the inertial body and the radius of gyration of the crankshaft as shown in FIG. 4 is suitable. This is because the energy on the inertial body side becomes large and more energy can be recovered. In this case, since the crankshaft serves as a speed reducer with respect to the inertial body, double torque is transmitted from the inertial body to the crankshaft.

  Next, a mechanism for realizing the magnitude relationship between the radius of gyration of the crankshaft and the radius of gyration of the inertial body found in the above consideration will be examined. First, the elliptical gear shown in FIG. 5, more specifically, the elliptical single-leaf gear, was considered to be adopted in the process of creating the present invention. With an elliptical gear, the radius of gyration can be substantially changed. Therefore, by appropriately combining two elliptical gears, the magnitude relation of the radius gyration shown in FIG. 3 and the magnitude relation of the radius gyration shown in FIG. Can be realized in real time.

  FIG. 6 is a diagram showing a meshed state of two elliptical gears when energy is stored from the crankshaft to the inertial body. The phases of the two elliptical gears are matched so that the elliptical gear of the inertial body has the maximum turning radius when the elliptical gear of the crankshaft has the minimum turning radius. This maximizes the energy stored in the inertial body from the crankshaft.

  FIG. 7 is a diagram showing a meshed state of two elliptical gears when energy is recovered from the inertial body to the crankshaft. The phases of the two elliptical gears are matched so that the elliptical gear of the inertial body has the minimum turning radius when the elliptical gear of the crankshaft has the maximum turning radius. As a result, the energy recovered from the inertial body to the crankshaft can be maximized.

  Next, whether or not the elliptical gear is actually applicable to the engine will be examined based on the relationship with the torque waveform in the in-line 4-cylinder engine. FIG. 8 is a diagram showing the timing of energy storage in the in-line four-cylinder engine. Since the torque generated on the crankshaft reaches a peak at a crank angle of 30 to 50 degrees, it is desirable to realize the relationship between the two elliptical gears shown in FIG. 6 at a crank angle of 30 to 50 degrees. On the other hand, FIG. 9 is a diagram showing the timing of energy recovery in the in-line four-cylinder engine. Energy recovery from the inertial body to the crankshaft should be performed near the "valley of torque" where the torque generated on the crankshaft becomes zero.

  However, when the elliptical gear is used, energy cannot be recovered at the above recovery timing. Since the "valley of torque" where the torque becomes zero is around a crank angle of 160 to 180 degrees, the interval from the timing of saving energy to the timing of energy recovery is 120 to 130 degrees. On the other hand, in the elliptical gear, since the maximum turning radius and the minimum turning radius have an angle difference of 180 degrees, if the energy saving timing is adjusted, the recovery timing is shifted, and if the energy recovery timing is adjusted, the saving timing is changed. It will shift.

  As a result of studying the problem of such an elliptical gear, the asymmetric gear has been adopted in the present invention. FIG. 10 is a diagram specifically showing the shape of the asymmetric gear on the crankshaft side according to the present embodiment. FIG. 11 is a diagram specifically showing the shape of the asymmetric gear on the inertial body side according to the present embodiment.

  As shown in FIG. 10, the asymmetric gear on the crankshaft side has a minimum turning radius at a crank angle of 40 degrees at which the generated torque peaks, and a turning radius at a crank angle of 160 degrees at which the generated torque becomes zero. Designed to be maximum. On the other hand, as shown in FIG. 11, the asymmetric gear on the inertial body side has a maximum turning radius at a crank angle of 40 degrees at which the generated torque reaches its peak, and a rotation radius at a crank angle of 40 degrees at which the generated torque becomes zero. Is designed to be maximum. Here, the minimum turning radius is 1 and the maximum turning radius is 2 on both the crankshaft side and the inertial body side, and the distance between the centers of the crankshaft side elliptical gear and the inertial body side elliptical gear is 3. Is calculated to be.

  FIG. 12 shows the crank mechanism of this embodiment side by side with the conventional crank mechanism. In a conventional crank mechanism, a piston 2 that reciprocates in a cylinder 1 is attached to a crank pin 6 of a crank shaft 4 via a connecting rod 3, and the reciprocating motion of the piston 2 is converted into a rotary motion by the crank shaft 4. A counterweight 5 is attached to the crankshaft 4 to remove unbalance during rotation.

  The crank mechanism of the present embodiment is a torque redistribution mechanism configured by using the asymmetric gears shown in FIGS. 10 and 11. The crank mechanism (torque redistribution mechanism using an asymmetrical gear) of the present embodiment includes a counter shaft 11 arranged in parallel with the crank shaft 4. The crankshaft 4 is provided with a first asymmetric gear 10, and the counter shaft 11 is provided with a second asymmetric gear 12 meshing with the first asymmetric gear 10.

  FIG. 13 is a diagram showing a state in which the two asymmetric gears 10 and 12 rotate in the crank mechanism of the present embodiment. The maximum torque generated in the crankshaft 4 due to the combustion pressure acting on the piston 2 is around a crank angle of 40 degrees at which the piston 2 is slightly lower than the top dead center crank angle of 0 degrees. Storage of energy from the crankshaft 4 to the inertial body including the second asymmetric gear 12 is performed at this timing. In the vicinity of the crank angle of 40 degrees, the distance from the center of rotation of the first asymmetric gear 10 to the contact point between the first asymmetric gear 10 and the second asymmetric gear 12 is minimized, and the distance from the center of rotation of the second asymmetric gear 12 to the first The distance to the contact point between the asymmetric gear 10 and the second asymmetric gear 12 is maximized. Therefore, the energy stored in the inertial body including the second asymmetric gear 12 is maximized.

  After that, the torque generated in the crankshaft 4 by the combustion pressure acting on the piston 2 becomes a minimum in the vicinity of the crank angle of 160 degrees before the bottom dead center. Energy recovery from the inertial body including the second asymmetric gear 12 to the crankshaft 4 is performed at this timing. In the vicinity of the crank angle of 160 degrees, the distance from the rotation center of the first asymmetric gear 10 to the contact point between the first asymmetric gear 10 and the second asymmetric gear 12 becomes maximum, and the first center from the rotation center of the second asymmetric gear 12 The distance to the contact point between the asymmetric gear 10 and the second asymmetric gear 12 is minimized. Therefore, the energy recovered from the inertial body including the second asymmetric gear 12 is maximized, and the valley of the torque output from the crankshaft 4 can be filled with the recovered energy.

  Then, when the crankshaft 4 rotates 240 degrees and the crank angle is 40 degrees again, the radius of gyration of the first asymmetric gear 10 is minimized and the radius of gyration of the second asymmetric gear 12 is maximized, including the second asymmetric gear. Energy is stored in the inertial body. Further, when the crankshaft 4 rotates 120 degrees and the crank angle of 160 degrees again, the radius of gyration of the first asymmetric gear 10 is maximized and the radius of gyration of the second asymmetric gear 12 is minimized. Energy is recovered from the inertial body containing it. Then, the energy storage and recovery at the above timing is repeated in a cycle of 360 degrees.

  Finally, an example in which the crank mechanism (torque redistribution mechanism) of the present embodiment is mounted on the crankshaft of an in-line four-cylinder engine will be described. FIG. 14 is a diagram showing an embodiment in which one set of asymmetric gears 10 and 12 is provided on the crankshaft 4. In this embodiment, the first asymmetric gear 10 is formed on the crank arm of the third cylinder. FIG. 15 is a diagram showing a waveform of torque output from the crankshaft 4 in this embodiment. In this embodiment, since energy is stored and recovered in a 360-degree cycle, torque can be redistributed only in the second cylinder and the third cylinder, and the crankshaft 4 is still used in the first cylinder and the fourth cylinder. There is a valley in the torque output from.

  FIG. 16 is a diagram showing an embodiment in which two sets of asymmetric gears 10 and 12 are provided on the crankshaft 4. In this embodiment, the first asymmetric gear 10 is formed on the crank arm of the third cylinder and the crank arm of the fourth cylinder. The respective second asymmetric gears 12 are rotatably mounted on a common counter shaft 11. FIG. 17 is a diagram showing a torque waveform obtained in this embodiment. In this embodiment, since energy is stored and recovered in a cycle of 180 degrees, the reallocation of torque can be realized in all the cylinders of the in-line four-cylinder engine. That is, in the case of an in-line four-cylinder engine, by providing asymmetric gears 10 and 12 in two cylinders whose crank angle phases are shifted by 180 degrees, or in all the cylinders, the valley of the torque output from the crankshaft 4 in each cylinder. Can be filled.

1 Cylinder 2 Piston 3 Connecting Rod 4 Crank Shaft 5 Counter Weight 6 Crank Pin 10 First Asymmetric Gear 11 Counter Shaft 12 Second Asymmetric Gear

Claims (1)

A crankshaft that converts the reciprocating motion of the piston into a rotary motion,
A counter shaft arranged parallel to the crank shaft,
A first asymmetric gear provided on the crankshaft;
A second asymmetric gear provided on the counter shaft and meshing with the first asymmetric gear,
The first asymmetrical gear and the second asymmetrical gear are
The distance from the rotation center of the first asymmetric gear to the contact point between the first asymmetric gear and the second asymmetric gear near the crank angle where the torque generated on the crankshaft is maximized by the combustion pressure acting on the piston. And the distance from the center of rotation of the second asymmetric gear to the contact point between the first asymmetric gear and the second asymmetric gear is maximized,
The distance from the rotation center of the first asymmetric gear to the contact point between the first asymmetric gear and the second asymmetric gear near the crank angle where the torque generated on the crankshaft due to the combustion pressure acting on the piston is minimized. And a distance from the center of rotation of the second asymmetric gear to the contact point between the first asymmetric gear and the second asymmetric gear are minimized. .

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