JP2023067536A - internal combustion engine - Google Patents

Abstract

To provide an internal combustion engine capable of suppressing vibration.SOLUTION: An internal combustion engine 1 comprises a cylinder block 10 having a plurality of cylinders 11, and intake and exhaust camshafts provided with intake and exhaust eccentric masses 23, 33. The plurality of cylinders has a first cylinder and a second cylinder. The internal combustion engine further comprises a second piston arranged at a position 180 degrees different in rotation in reciprocating motion from a first piston of the first cylinder, and performing reciprocating motion in the second cylinder.SELECTED DRAWING: Figure 5

Description

The present invention relates to internal combustion engines.

2. Description of the Related Art Conventionally, an internal combustion engine such as a two-cylinder engine mounted on a vehicle such as a four-wheeled vehicle is provided with a balance shaft to suppress vibration of the internal combustion engine. There is also a demand for a technology that eliminates the need for balance shafts.

JP 2013-007334 A

However, when the balance shaft is removed, there is a demand for a technique for suppressing the vibration of the internal combustion engine in place of the balance shaft.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an internal combustion engine capable of suppressing vibration.

In order to solve the above-described problems and achieve the object, an internal combustion engine according to the present invention comprises a cylinder block having a plurality of cylinders, and a member for opening and closing intake valves or exhaust valves of the cylinders, wherein an eccentric mass is provided. a camshaft having a

According to this configuration, when the cylinder block is tilted due to the expansion or compression of the air-fuel mixture in the cylinder, the internal combustion engine generates centrifugal force in the opposite direction, thereby suppressing vibration even without a balance shaft. can be done.

Further, the internal combustion engine according to the present invention is provided with the eccentric mass that generates centrifugal force in a direction opposite to a direction in which the cylinder block is tilted by rotation of the camshaft.

According to this configuration, the internal combustion engine can suppress vibration without the balance shaft.

Further, the internal combustion engine according to the present invention includes the eccentric mass provided in the case of the variable valve mechanism provided on the camshaft.

According to this configuration, the internal combustion engine can suppress vibration without the balance shaft.

Further, the internal combustion engine according to the present invention includes the eccentric mass provided at the tip of the camshaft.

According to this configuration, the internal combustion engine can suppress vibration without the balance shaft.

Further, an internal combustion engine according to the present invention is an internal combustion engine having a first cylinder and a second cylinder as the plurality of cylinders, the first piston reciprocating in the first cylinder, and the first piston a second piston arranged at a position 180 degrees different from the first piston in rotation in the reciprocating motion of and reciprocating in the second cylinder.

According to this configuration, the internal combustion engine can suppress vibration without the balance shaft.

The internal combustion engine according to the present invention has the effect of suppressing vibration.

FIG. 1 is a perspective view showing an example of an internal combustion engine according to this embodiment. FIG. 2 is a perspective view showing an example of the internal combustion engine according to this embodiment. FIG. 3 is a top view showing an example of the internal combustion engine according to this embodiment. FIG. 4 is a cross-sectional view schematically showing a cylinder block of the internal combustion engine according to this embodiment. FIG. 5 is a cross-sectional view schematically showing an expanded state of the cylinder block of the internal combustion engine according to this embodiment. FIG. 6 is a cross-sectional view schematically showing a compressed state of a cylinder block of the internal combustion engine according to this embodiment.

An example of an embodiment of an internal combustion engine according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a perspective view showing an example of an internal combustion engine 1 according to this embodiment. FIG. 2 is a perspective view showing an example of the internal combustion engine 1 according to this embodiment. FIG. 3 is a top view showing an example of the internal combustion engine 1 according to this embodiment.

In this embodiment, a Cartesian coordinate system consisting of X-axis, Y-axis and Z-axis is defined. The X-axis direction is a direction parallel to the intake camshaft 20 . The Y-axis direction is the height direction of the internal combustion engine 1 . The Z-axis direction is a direction orthogonal to the X-axis direction and the Y-axis direction.

The internal combustion engine 1 according to this embodiment is, for example, a four-stroke engine having two cylinders 11 (see FIG. 4). The cylinder 11 has two intake valves and two exhaust valves. The internal combustion engine 1 includes an intake camshaft 20 having an intake cam 21 for opening and closing an intake bubble, and an exhaust camshaft 30 having an exhaust cam 31 for opening and closing an exhaust bubble.

The intake camshaft 20 has an intake cam sprocket 22 at one end. The intake cam sprocket 22 is a gear connected to a timing chain that rotates the intake camshaft 20 . The intake camshaft 20 is rotated by the timing chain so that the intake cam 21 opens and closes the intake bubble.

The intake camshaft 20 also has an intake eccentric mass 23 . The intake eccentric mass 23 is a weight that is provided on the intake camshaft 20 and shifts the center of gravity of the cylinder block 10 (see FIG. 4). The intake eccentric mass 23 is provided, for example, at the tip of the intake camshaft 20 . The intake eccentric mass 23 is provided at the tip of the intake camshaft 20 opposite to the side on which the intake cam sprocket 22 is provided.

The exhaust camshaft 30 has an exhaust cam sprocket 32 at one end. The exhaust cam sprocket 32 is a gear connected to a timing chain that rotates the exhaust camshaft 30 . The exhaust camshaft 30 is rotated by the timing chain so that the exhaust cam 31 opens and closes the exhaust bubble.

The exhaust camshaft 30 also has an exhaust eccentric mass 33 . The exhaust eccentric mass 33 is a weight provided on the exhaust camshaft 30 to shift the center of gravity of the cylinder block 10 (see FIG. 4). The exhaust eccentric mass 33 is provided, for example, at the tip of the exhaust camshaft 30 . Also, the exhaust eccentric mass 33 is provided at the tip of the exhaust camshaft 30 opposite to the side on which the exhaust cam sprocket 32 is provided.

FIG. 4 is a cross-sectional view schematically showing the cylinder block 10 of the internal combustion engine 1 according to this embodiment.

Cylinder block 10 has cylinders 11 . The cylinder 11 incorporates a cylindrical piston 12 . The internal combustion engine 1, which is a four-stroke engine, executes four strokes of intake, compression, expansion, and exhaust as one cycle.

During intake, the intake camshaft 20 opens the intake valves. The piston 12 descends downward in the Y-axis direction. As a result, the piston 12 takes in a mixture of air and fuel.

In compression, the piston 12 rises upward in the Y-axis direction. As a result, the piston 12 compresses the intake air-fuel mixture. Also, during compression, the air-fuel mixture is compressed by the piston 12, so the pressure in the cylinder 11 increases.

In expansion, the spark plug ignites the compressed air-fuel mixture and expands the air-fuel mixture. As a result, the piston 12 is pushed downward in the Y-axis direction. Also, during expansion, the air-fuel mixture expands, so the pressure in the cylinder 11 increases.

On exhaust, the exhaust camshaft 30 opens the exhaust valve. The piston 12 rises upward in the Y-axis direction. Thereby, the cylinder 11 discharges the exhaust gas. Thus, the internal combustion engine 1 causes the piston 12 to reciprocate by executing four strokes of intake, compression, expansion, and exhaust as one cycle.

Piston 12 is connected to connecting rod 13 that transmits the reciprocating motion of piston 12 to crankshaft 40 . The connecting rod 13 is connected with a crankpin 43 of the crankshaft 40 .

The crankshaft 40 has a crank journal 41 , a crank arm 42 and a crankpin 43 . The crank journal 41 is the rotating shaft of the crankshaft 40 . The crank arm 42 connects the crank journal 41 and the crank pin 43 . The crank pin 43 rotates around the crank journal 41 as a rotation axis. Thereby, the crankshaft 40 converts the reciprocating motion of the piston 12 into rotary motion.

When the internal combustion engine 1 is a two-cylinder engine having a first cylinder and a second cylinder as the plurality of cylinders 11, the crankpins 43 of the respective cylinders 11 are arranged at diametrically opposite positions. More specifically, when the position of the crankpin 43 of the No. 1 cylinder is at the lower end of the rotational motion, the position of the crankpin 43 of the No. 2 cylinder is positioned at the upper end of the rotational motion. That is, the crankpin 43 of the first cylinder and the crankpin 43 of the second cylinder are arranged with an interval of 180 degrees in rotational motion. In this case, the crankpin 43 of the first cylinder and the crankpin 43 of the second cylinder rotate with an interval of 180 degrees, thereby canceling out the inertial force in the Y-axis direction.

In other words, the internal combustion engine 1 further includes a first piston that reciprocates in the first cylinder and a second piston that reciprocates in the second cylinder. The second piston is positioned 180 degrees different in rotation from the first piston in the reciprocating motion of the first piston. For example, when the first piston is positioned at the upper end of reciprocating motion, the second piston is arranged to be positioned at the lower end of reciprocating motion. And when the first piston descends in reciprocation, the second piston ascends in reciprocation. The inertial force in the Y-axis direction is canceled by the descent of the first piston and the rise of the second piston.

However, when the crank pin 43 of the first cylinder and the crank pin 43 of the second cylinder are rotated with an interval of 180 degrees, for example, the expansion of the second cylinder is performed after the expansion of the first cylinder. It occurs after the pin 43 rotates 180 degrees. The expansion of the next No. 1 cylinder occurs after the No. 2 cylinder expands and the crank pin 43 rotates 540 degrees. Thus, expansion occurs at uneven intervals. In other words, the internal combustion engine 1, which has four strokes as one cycle, expands every 0.5 cycles.

Here, torque is generated in the cylinder block 10 during expansion and compression. In other words, in expansion and compression the cylinder block 10 tilts. The inertial force in the Y-axis direction is canceled by providing a 180-degree gap between the crankpin 43 of the first cylinder and the crankpin 43 of the second cylinder. However, since the torque generated in the cylinder block 10 is in the Z-axis direction, it is generated regardless of the cancellation of the inertial force in the Y-axis direction.

Next, vibration caused by the cylinder block 10 due to torque fluctuation will be described.

FIG. 5 is a cross-sectional view schematically showing an expanded state of the cylinder block 10 of the internal combustion engine 1 according to this embodiment. FIG. 6 is a cross-sectional view schematically showing a compressed state of the cylinder block 10 of the internal combustion engine 1 according to this embodiment. The left side of FIGS. 5 and 6 is the rear of the vehicle on which the internal combustion engine 1 is mounted, and the right side of FIGS. 5 and 6 is the front of the vehicle on which the internal combustion engine 1 is mounted.

Cylinder block 10 has a plurality of cylinders 11 . For example, cylinder block 10 has two cylinders 11 . The internal combustion engine 1 also includes a camshaft, which is a member for opening and closing intake valves or exhaust valves of the cylinders 11 and has an eccentric mass. That is, the internal combustion engine 1 includes an intake camshaft 20 and an exhaust camshaft 30 . The intake camshaft 20 has an intake eccentric mass 23 that changes the center of gravity of the cylinder block 10 . The exhaust camshaft 30 has an exhaust eccentric mass 33 that changes the center of gravity of the cylinder block 10 .

As shown in FIG. 5, when the cylinder block 10 expands, a force is applied in the direction in which the cylinder block 10 inclines rearward due to reaction to the expansion of the air-fuel mixture. At this time, the intake eccentric mass 23 generates centrifugal force in the direction opposite to the direction in which the cylinder block 10 tilts due to the rotation of the intake camshaft 20 . Similarly, the exhaust eccentric mass 33 generates centrifugal force in the direction opposite to the direction in which the cylinder block 10 tilts due to the rotation of the exhaust camshaft 30 . That is, the intake eccentric mass 23 and the exhaust eccentric mass 33 generate centrifugal force in the forward direction opposite to the backward direction in which the cylinder block 10 tilts. Then, the centrifugal force generated by the intake eccentric mass 23 and the exhaust eccentric mass 33 and the force acting in the direction of tilting the cylinder block 10 backward due to the expansion of the air-fuel mixture are canceled.

As shown in FIG. 6 , during compression, the cylinder block 10 receives a force in a direction in which the cylinder block 10 is tilted forward due to reaction to the compression of the air-fuel mixture. At this time, the intake eccentric mass 23 generates centrifugal force in the direction opposite to the direction in which the cylinder block 10 tilts due to the rotation of the intake camshaft 20 . Similarly, the exhaust eccentric mass 33 generates centrifugal force in the direction opposite to the direction in which the cylinder block 10 tilts due to the rotation of the exhaust camshaft 30 . That is, the intake eccentric mass 23 and the exhaust eccentric mass 33 generate centrifugal force in the rearward direction opposite to the forward direction in which the cylinder block 10 tilts. The centrifugal force generated by the intake eccentric mass 23 and the exhaust eccentric mass 33 cancels the force acting in the direction in which the cylinder block 10 is tilted forward due to the expansion of the air-fuel mixture.

In addition, the intake eccentric mass 23 and the exhaust eccentric mass 33 are provided at positions far from the crank journal 41 which is the axis on which the cylinder block 10 tilts. Therefore, the intake eccentric mass 23 and the exhaust eccentric mass 33 can suppress vibration even if they have a small mass.

Thus, the internal combustion engine 1 according to this embodiment includes a cylinder block 10 having a plurality of cylinders 11 . The internal combustion engine 1 also includes an intake camshaft 20 that opens and closes the intake valves of the cylinders 11, and an exhaust camshaft 30 that opens and closes the exhaust valves. The intake camshaft 20 and the exhaust camshaft 30 each have an eccentric mass that changes the center of gravity of the cylinder block 10 by their own rotation.

As a result, when the cylinder block 10 tilts backward as the piston 12 descends during the expansion of the air-fuel mixture in the cylinder 11, the intake eccentric mass 23 and the exhaust eccentric mass 33 are connected to the intake camshaft 20 and Centrifugal force is generated forward by rotation with the exhaust camshaft 30 . Further, when the cylinder block 10 tilts forward as the piston 12 rises during the compression of the air-fuel mixture in the cylinder 11, the intake eccentric mass 23 and the exhaust eccentric mass 33 move between the intake camshaft 20 and the exhaust mass. A centrifugal force is generated rearward by rotation with the camshaft 30 for the rear. Therefore, the intake eccentric mass 23 and the exhaust eccentric mass 33 can suppress vibration of the cylinder block 10 . In other words, the internal combustion engine 1 can suppress vibration even if the balance shaft is removed.

Since vibration can be suppressed even if the balance shaft is removed, the internal combustion engine 1 can be mounted not only on a two-wheeled vehicle such as a motorcycle but also on a four-wheeled vehicle such as a passenger car.

Further, in the above embodiment, the intake eccentric mass 23 is provided at the tip of the intake camshaft 20 and the exhaust eccentric mass 33 is provided at the tip of the exhaust camshaft 30 . The intake eccentric mass 23 and the exhaust eccentric mass 33 may be provided in a case that houses a variable valve mechanism (VVT) that varies the timing of opening and closing the intake valve and the exhaust valve.

For example, when both the intake camshaft 20 and the exhaust camshaft 30 are provided with variable valve mechanisms, the intake eccentric mass 23 is provided with the variable valve mechanism of the intake camshaft 20 and the exhaust eccentric mass 23 is provided with a variable valve mechanism. The mass 33 is provided with a variable valve mechanism for the exhaust camshaft 30 . In addition, although the intake camshaft 20 is provided with a variable valve mechanism, if the exhaust camshaft 30 does not have a variable valve mechanism, the intake eccentric mass 23 is used by the variable valve mechanism of the intake camshaft 20. The exhaust eccentric mass 33 is provided at the tip of the exhaust camshaft 30 .

Also, the intake cam sprocket 22 may be the tip of the intake camshaft 20 . That is, the intake eccentric mass 23 may be provided on the intake cam sprocket 22 . Moreover, the exhaust cam sprocket 32 may be the tip of the exhaust cam shaft 30 . That is, the exhaust eccentric mass 33 may be provided on the exhaust cam sprocket 32 .

Further, in the above embodiment, the internal combustion engine 1 has been described as a two-cylinder engine. However, the internal combustion engine 1 may also be a three-cylinder engine. For example, in the case of a 3-cylinder engine, it can be applied by deactivating any cylinder 11 . Moreover, even if it is a four-cylinder engine, it can be applied when one of the cylinders 11 is stopped.

The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present invention.

Reference Signs List 1 internal combustion engine 10 cylinder block 11 cylinder 12 piston 13 connecting rod 20 intake camshaft 21 intake cam 22 intake cam sprocket 23 intake eccentric mass 30 exhaust camshaft 31 exhaust cam 32 exhaust cam sprocket 33 exhaust eccentric mass 40 crankshaft 41 crank journal 43 crank pin 42 crank arm

Claims (5)

a cylinder block having a plurality of cylinders;
a camshaft, which is a member for opening and closing an intake valve or an exhaust valve of the cylinder and has an eccentric mass;
internal combustion engine. The eccentric mass generates centrifugal force in a direction opposite to a direction in which the cylinder block is tilted by rotation of the camshaft.
2. Internal combustion engine according to claim 1. The eccentric mass is provided in a case of a variable valve mechanism provided on the camshaft,
An internal combustion engine according to claim 1 or claim 2. The eccentric mass is provided at the tip of the camshaft,
An internal combustion engine according to claim 1 or claim 2. An internal combustion engine having a first cylinder and a second cylinder as the plurality of cylinders,
a first piston that reciprocates in the first cylinder;
A second piston that is arranged at a position 180 degrees different from the first piston in rotation in the reciprocating motion of the first piston and performs reciprocating motion in the second cylinder,
An internal combustion engine as claimed in any one of claims 1 to 4.

Images