JPH04307145A - Balancer unit in straight four-cylinder internal combustion engine for vehicle - Google Patents

Abstract

PURPOSE:To reduce the secondary vibromotive force in the vertical direction by means of reciprocation mass and secondary vibratory moment by explosion in a straight 4-cylinder internal combustion engine, without entailing any oversize of the engine and an increase in the weight. CONSTITUTION:One balancer shaft 10 provided with an eccentric type balance weight 13 is installed so as to parallel a crankshaft 3 in an internal combustion engine and to make this balancer shaft 10 rotate at double speed in reverse to the rotational direction of the crankshaft 3, and a line 14 connecting the axial center of this balancer shaft 10 and the torque roll axial center 5 in the engine is tilted as far as an angle 2alpha equal to a phase shift angle S2 in the secondary vibratory moment by explosion in relation to an orthogonal line 15 crossing with a right angle in relation to an axial line 6a of each cylinder bore 6 of respectively cylinders A1-A4.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is directed to an in-line four-wheel drive system mounted on a vehicle.
The present invention relates to a balancer device that reduces vertical vibrations generated by reciprocating parts of a cylinder internal combustion engine and vibrations generated in the rotational direction of the internal combustion engine due to explosive combustion.

0002

[Prior Art] In an in-line four-cylinder internal combustion engine, the largest excitation force in the vertical direction is the secondary excitation force due to the reciprocating mass, and the excitation moment in the rotational direction of the internal combustion engine is The largest of these is the secondary excitation moment caused by the explosion. Therefore, “automotive technology” V
ol. No. 9, 1976, pages 711 to 716 disclose that in the in-line four-cylinder internal combustion engine, a balancer shaft with eccentric balance weights is arranged parallel to the crank axis on both the left and right sides of the in-line four-cylinder internal combustion engine. By rotating the shafts in opposite directions at twice the rotational speed of the crankshaft and shifting both balancer shafts in the vertical direction, the secondary vibrational force due to the reciprocating mass and the explosion are generated. It has been described that the second-order vibration moment caused by the oscillation can be eliminated or reduced.

0003

[Problem to be solved by the invention] However, in this way,
Placing two balancer shafts, each with an eccentric balance weight, on both the left and right sides of the internal combustion engine not only significantly increases the width of the internal combustion engine, but also increases the Since two power transmission mechanisms are required, and the length of the internal combustion engine in the crankshaft direction increases, there is a problem that not only the size of the internal combustion engine becomes larger, but also the weight of the engine increases. The present invention eliminates or reduces the secondary excitation force due to the reciprocating mass and the secondary excitation moment due to the explosion by a single balancer shaft equipped with an eccentric balance weight. A technical problem is to provide a balancer device that can perform the following functions.

0004

[Means for Solving the Problem] In order to achieve this technical problem, the present invention provides a body frame for a vehicle.
In an in-line 4-cylinder internal combustion engine that is mounted so that it can roll around the torque roll axis via an elastic engine mount, the power transmitted from the crankshaft allows the engine to rotate twice as much in the opposite direction to the rotational direction of the crankshaft. A balancer shaft that rotates at a high speed is arranged parallel to the crankshaft, and an eccentric balance weight is attached to the balancer shaft so that when the piston of each cylinder is at the top dead center, the eccentric balance weight is attached to the balancer shaft. While the core type balance weight is provided in a phase that points downward, when the internal combustion engine is viewed from the axial direction of the crankshaft, a line connecting the axis of the balancer shaft and the torque roll axis is the axis of the cylinder bore. It is configured to be inclined by an angle equal to the phase shift angle in the secondary excitation moment due to an explosion with respect to orthogonal lines that intersect at right angles.

[0005]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the figure, reference numeral 1 indicates the body frame of the vehicle, and reference numeral 2 indicates the four cylinders A1, A2, A3,
A4 is an in-line four-cylinder internal combustion engine arranged in series with one crankshaft 3, and this internal combustion engine 2 is connected to the body frame 1 through at least a pair of left and right elastic engine mounts 4. The cylinder A is mounted so as to be rollable around the torque roll axis 5, and each of the cylinders A
1, A2, A3, A4, a cylinder bore 6, a piston 7 with a piston pin 7a that reciprocates within the cylinder bore 6, and a piston pin 7 in the piston 7.
a and a connecting rod 9 that connects the crank pin 8 of the crankshaft 3. In this case, the crank pins 8 in the second cylinder A2 and the third cylinder A3 are shifted by 180 degrees in crank angle with respect to the crank pins 8 in the first cylinder A1 and the fourth cylinder A4, and the ignition order is as follows. The order is set as follows: first cylinder A1 - third cylinder A3 - fourth cylinder A4 - second cylinder A2.

A balancer shaft 10 is disposed on a side surface of the internal combustion engine 2 so that an axis 10a of the balancer shaft 10 extends parallel to the axis 3a of the crankshaft 3. , a small diameter gear 11 fitted to one end of the large diameter gear 1 fitted to the crankshaft 3;
2, the crankshaft 3 rotates in the direction of arrow C, which is opposite to the crankshaft 3 rotating in the direction of arrow B, at twice the rotational speed. An eccentric balance weight 13 is attached to the balancer shaft 8 for each cylinder A1.
, A2, A3, and A4 are at the top dead center of the upper limit of upward movement, the balance weight 13 is fixed in a downward phase.

When the internal combustion engine 2 is viewed from the axial direction of the crankshaft 3, the balancer shaft 10
An orthogonal line 15 in which a line 14 connecting the axis of the engine and the torque roll axis 5 intersects at right angles to the axis 6a of the cylinder bore 6 in each of the cylinders A1, A2, A3, and A4.
In contrast, it is configured to be tilted by an angle 2α equal to a phase shift angle θ2 in a secondary excitation moment due to an explosion, which will be described in detail later.

By the way, in the in-line four-cylinder internal combustion engine, there is a secondary excitation force F2 in the vertical direction due to the mass of reciprocating parts such as the piston 7, piston pin 7a, and connecting rod 9 in all cylinders A1, A2, A3, and A4. is the mass of the reciprocating parts such as the piston 7, piston pin 7a and connecting rod 9 in all cylinders A1, A2, A3, A4, m is the crank radius, r is the crank angle, and is the crank angle θ.
, if the length of the connecting rod 9 is l, and the upward direction is positive, then

[Equation 1] In addition, in the in-line four-cylinder internal combustion engine, if the excitation moment in the rotational direction of the crankshaft due to an explosion is decomposed into a Fourier series, the second-order excitation moment is the largest, and this second-order excitation moment is The secondary vibration moment T at the rotation speed and load that is frequently used in a vehicle varies depending on the number of rotations and load, but the peak value of the secondary vibration moment is T2, the rotational angular velocity of the crankshaft 3 is ω, If the phase shift angle of the second-order excitation moment is θ2, then

[Math 2] It is.

On the other hand, the amount of unbalance due to the balance weight 13 fixed to the balancer shaft 10 is expressed as (m
r/2l)r, the centrifugal force Fv generated by the rotation of the balancer shaft 10 is:

[Math 3] become.

[0010] When the excitation force F2 in the above ``Equation 1'' and the vertical component Fv1 of the excitation force acting on the torque roll axis 5 due to the centrifugal force Fv in the ``Equation 3'' are combined,

[Equation 4], and the horizontal component Fv2 of the excitation force acting on the torque roll axis 5 due to the rotation of the balancer shaft 10 is

[Mathematical 5] becomes. Therefore, if we combine the above "Math. 4" and "Math. 5", we get

[Equation 6] Therefore, the secondary excitation force in the vertical direction in the in-line four-cylinder internal combustion engine 2 is expressed by the balance weight 1 as described above.
By providing a single balancer shaft 10 with the number 3, the centrifugal force can be reduced to half the magnitude of the case of the above-mentioned "Equation 1", that is, the case where the balancer shaft 10 is not provided. Can be done.

On the other hand, if the distance from the axis of the balancer shaft 10 to the torque roll axis 5 is L, the vibration moment generated around the torque roll axis 5 due to the rotation of the balancer shaft 10 is:

[Math. 7] Therefore, if we combine this "Math. 7" and the "Math. 2" above, we get

[Equation 8] becomes. In this case, an orthogonal line 15 intersects a line 14 connecting the axis of the balancer shaft 10 and the torque roll axis 5 at right angles to the axis 6a of the cylinder bore 6 in each cylinder A1, A2, A3, A4. On the other hand, since θ2 = 2α due to the inclination by an angle 2α equal to the phase shift angle θ2 in the secondary excitation moment due to the explosion, the above “Equation 8” is

[Math. 9] become. Here, L is

[Math. 10] Therefore, in the above "Math. 9"

By setting the distance L from the axis of the balancer shaft 10 to the torque roll axis 5 so that the term [Equation 11] becomes zero in the frequently used rotation speed and load range, the explosion-induced secondary If the next excitation moment is made zero in the frequently used rotation speed and load range, the second excitation moment becomes
This allows reduction over a wide operating range of the internal combustion engine 2.

0012

As described above, according to the present invention, the secondary excitation force in the vertical direction due to the reciprocating mass in an in-line four-cylinder internal combustion engine and the secondary excitation moment due to an explosion can be reduced by using an eccentric type By providing a single balancer shaft with a balance weight of
In other words, in order to reduce the secondary excitation force in the vertical direction due to the reciprocating mass and the secondary excitation moment due to the explosion, it is sufficient to provide only one balancer shaft. It is possible to prevent the width and weight of the internal combustion engine from increasing significantly, and the structure of the internal combustion engine can be simplified by requiring only one power transmission mechanism from the crankshaft to the balancer shaft, making the internal combustion engine smaller and lighter. It has the effect that can be achieved.

[Brief explanation of drawings]

FIG. 1 is a front view of an internal combustion engine viewed from the axial direction of a crankshaft.

FIG. 2 is a perspective view showing the overall outline.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

[Explanation of symbols]

1 Body frame 2
In-line 4-cylinder internal combustion engine A1, A2, A
3, A4 cylinder 3
Crankshaft 4 Elastic engine mount 5 Torque roll axis 6 Cylinder bore 6a
Cylinder bore axis 7
Piston 8 Crank pin 9
Connecting rod 10 Balancer shaft 13 Balance weight 14
Line 15 connecting the axis of the balancer shaft and the torque roll axis Orthogonal line

Claims (1)

[Claims] Claim 1: An in-line four-cylinder internal combustion engine that is mounted on a vehicle body frame via an elastic engine mount so as to be able to roll around a torque roll axis; A balancer shaft that rotates at twice the rotational speed in the opposite direction to the rotational direction of the crankshaft is arranged parallel to the crankshaft, and an eccentric balance weight is attached to the balancer shaft. The eccentric balance weight is provided in a phase such that it faces downward when the piston of each cylinder is at the top dead center, and when the internal combustion engine is viewed from the axial direction of the crankshaft, the axial center of the balancer shaft and the torque The line connecting the roll axis,
A series 4 for a vehicle, characterized in that it is inclined by an angle equal to the phase shift angle in the secondary excitation moment due to an explosion with respect to a perpendicular line that intersects at right angles with the axis of the cylinder bore.
Balancer device in cylinder internal combustion engine.