JPS6013930A - Vibration damping apparatus for multi-cylinder internal-combustion engine - Google Patents

Abstract

PURPOSE:To reduce the vibration of an engine capable of changing the number of cylinders to be operated at the time of its partial-cylinder operation, by providing centrifugal resonators having respective pivotal points in the plane perpendicular to the main shaft of the engine at the positions thereof spaced radially outward from the center of a turning shaft. CONSTITUTION:A flywheel 2 is fixed to the rear end of the main shaft of an engine which is designed to be capable of changing the number of cylinders to be operated, and centrifugal resonators 4 are disposed at the intervals of 120 deg. in the plane 3 of the flywheel 2 located on the side of the cylinders in the manner that they have respective pivotal points B at the positions spaced radially outward from the center of a turning shaft 1 by a distance R and the distance from the point B to the center G of gravity of each resonator 4 is (r). In respect of the formula, n<2>=R/r, representing resonance of the resonators 4, the degree n of harmonic oscillation is selected to be 1-2. By employing such an arrangement, it is enabled to absorb and reduce vibration of the engine at the time of its partial-cylinder operation.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to vibration reduction in a multi-cylinder internal combustion engine that performs so-called air count control, in which the operation of some cylinders is stopped in the engine light load operating range to perform partial cylinder operation. Regarding equipment.

(Prior art)? ), rather the torque fluctuation increases, and the smoothness of rotation is significantly impaired.

For this reason, an internal combustion engine has been proposed that avoids a drop in cylinder pressure by opening the intake valve of the cylinder on the idle side near the bottom dead center when the engine is idle to supply air.
-115002).

This was proposed for 4-cylinder engines, where the effect of reducing torque fluctuations by securing in-cylinder pressure in the side cylinders is most noticeable during the rest I period, and in 4-cylinder engines, the pistons operate in the same phase. When the intake and exhaust valves of two cylinders (1st and 4th cylinders or 2nd and 3rd cylinders) are closed, the crank angle of the two cylinders on the idle side is 360.
The compression action is performed at the same time and 180 degrees out of phase with the operating cylinder, and the sum of the peak values is approximately the same as the combustion peak value of one operating cylinder. As long as the above-mentioned compression action is performed reliably, even partial cylinder operation with only two cylinders can provide the same smoothness as simultaneous operation with four cylinders.

In other words, even though only two cylinders are in partial cylinder operation, the combined torque of the four cylinders causes torque fluctuations for every 180 degrees of crank angle, just like when all four cylinders are operated at the same time (solid line in Figure 2). . Note that the broken line in the figure shows the torque fluctuation when the in-cylinder pressure of the cylinder on the idle side decreases due to blow-by, and the torque fluctuation occurs only every 360 degrees of crank angle.

Incidentally, the excitation force caused by the explosion pressure acts on the cylinder block as a reaction force of the torque applied to the crankshaft, and therefore causes forced vibrations that periodically change as the engine rotates.

Among these forced vibrations, what is especially felt is the first-order vibration component, that is, the vibration with one cycle of one engine revolution (360 degrees of crank angle). Since the explosion pressure is generated twice in rotation, this primary component is hardly produced.

However, when it comes to partial cylinder operation with two cylinders, engine 1
Since the explosion pressure is generated only once per rotation, the first-order component becomes extremely large (in terms of vibration energy, it becomes larger than other second-order or higher-order components), causing the vibration that can be felt. As mentioned above, in systems that supply intake air to the cylinder on the idle side to maintain cylinder pressure, compression pressure is generated twice per engine revolution, so the vibration of the primary component is greatly reduced. Therefore, in this four-cylinder engine, not only the torque fluctuation is reduced, but also the vibration that is felt is reduced.

By the way, one of the vibrations during such partial cylinder operation is
The next component is particularly problematic in the engine's low rotational speed range, where the period in which compression pressure occurs is long.

Since human senses are logarithmic, even if the vibration energy is reduced by, for example, one-tenth, it only feels like it has been halved, and this leaves some dissatisfaction when compared to full-cylinder operation.

Furthermore, since compression pressure is not generated twice per engine revolution, the second-order component, which has two cycles per engine revolution, becomes quite large, and this second-order component becomes a vibration that contributes to the noise inside the cabin. Problems arise in the form of growth.

Therefore, in order to further reduce the secondary component of this vibration, for example, increasing the inertial mass of the flyboiler can be considered.While it is true that vibration can be reduced during partial cylinder operation, it is difficult to switch to full cylinder operation. Therefore, not only is a large inertial mass unnecessary, but it also causes a decline in acceleration performance and fuel efficiency.

Furthermore, in the case of a 6-cylinder engine that similarly performs partial cylinder operation, even if intake air is supplied to the cylinder on the idle side when the engine is at rest, it will only have the effect of preventing oil buildup, and will only reduce torque fluctuations. No effect occurs.

For example, if half of the cylinders (cylinders 1, 2, and 3 or cylinders 4, 5, and 6) are set to be inactive, and auxiliary air supply is performed during the inactive period, the in-cylinder pressure of the inactive cylinders will decrease. The peaks are all shifted with a phase difference of 120 degrees and do not overlap each other, and since the compression peak of any one of the cylinders on the idle side is always superimposed on the peak of the explosion pressure of the cylinder on the active side, it is rather possible to reduce torque fluctuations. This is for the purpose of promoting it.

Therefore, in a 6-cylinder engine, the vibration when shifting to partial cylinder operation is originally large, and in this case, 1.5
The order becomes a problem.

(Object of the Invention) Therefore, an object of the present invention is to provide a device for reducing vibrations during partial cylinder operation of a multi-cylinder internal combustion engine by removing low-order components of vibrations that are noticeable during partial cylinder operation. do.

(Structure and Effects of the Invention) The present invention provides a multi-cylinder body having a 1L side cylinder having a means for regulating the opening operation of intake valves and exhaust valves in a light load operating range and an operating side cylinder that is always operated. Configure the internal combustion engine by adding the following:

In other words, within a plane perpendicular to the main shaft of the engine or a rotating shaft synchronized with the main shaft, there is a radius radially outward from the center of the rotating shaft.
A resonant centrifugal pendulum is set up with point B, which is located J away, as a fulcrum, and the distance from this fulcrum to the center of gravity G is r, and the resonance formula n'=
Behind R/r, the order n of harmonic vibration is set to 1 to 2.

Centrifugal force pendulums reduce torsional vibrations that occur in the crankshaft, which is an elastic body, due to torque fluctuations.
This is not a normal method that reduces high-order vibration components of ≧3, but reduces low-order vibration components of n=1 to 2.

(Example) The following description will be given based on the illustrated embodiment.

FIG. 3 is a front view of one embodiment of the present invention, and FIG. 4 is a sectional view taken along the line X-x in FIG. 3.

2 in the figure is a flywheel attached to the rear end of the main shaft 1 (crankshaft) of the engine, and the cylinder side plane 3 of flywheel 2
Above is a resonant centrifugal pendulum 4 whose fulcrum is a point B which is located radially outward from the center J of the rotating shaft 1 by a distance R (referred to as the radius of rotation), and whose distance from this point B to the center of gravity G is r. 12
Arranged every 0 degrees. Note that 5 is the clutch part.

This resonant centrifugal force pendulum 4 is a type of dynamic damper.General dynamic dampers with mechanical springs have a resonant frequency that is uniquely determined by the specifications of the spring and quality. Although it is possible to reduce torsional vibration, in other rotation speed ranges, there are problems such as resonance and an increase in torsional vibration.
It is unsuitable when operating over a wide range of rotational speeds, such as in internal combustion engines for automobiles.

On the other hand, in the centrifugal pendulum 4, as the rotating body (flywheel 2) rotates, a centrifugal force r(I)'<ω is the angular frequency of the flywheel 2) acts on the center of gravity G of the pendulum 4.

The motion of the pendulum 4 in the field of this J:tsuna centrifugal force rω2 is
You can think of it in the same way as the behavior of a simple pendulum in a field of gravity Q,
Therefore, the natural angular frequency ωn of the middle terminal is ωn=(L-)
'T (/ is the distance between the fulcrum and the center of gravity of the simple pendulum), so by replacing the gravity 9 in this equation with the centrifugal force rω', the natural angular frequency of the centrifugal pendulum 4 is 0]1) ωn
-ωf1-F'2- is stopped.

What this formula means is that the natural frequency of the centrifugal pendulum 4 is proportional to the frequency (rotation speed) of the flywheel 2 (the angular vibration frequencies ωn and ω change as the rotation speed of the flywheel 2 changes). , following this, the natural frequency of the centrifugal pendulum 4 (
Since the resonance frequency (resonance frequency) changes, the centrifugal pendulum 4 has the ability to absorb vibrations over a wide rotational speed range of the flywheel 2.

The principle of such a centrifugal pendulum 4 is well known;
There is an example of its use in absorbing torsional vibrations of the crankshaft of a multi-cylinder internal combustion engine (see Mechanical Vibration Theory, published by Corona Publishing, August 1970, p. 241).

According to this example, for the centrifugal pendulum 4,
The resonance equation using r is given as follows.

n2=R/r...(1) In this equation (1), n is the order of harmonic vibration, and the meaning of equation (1) is, for example, to remove the first order of vibration, use n-1 as n-1. By substituting it into the above equation, R and r can be designed to be 1-R,/r.

However, in a normal multi-cylinder internal combustion engine, low-order vibration components such as n = 1 to 2 are accommodated by increasing the number of cylinders.
is at least 3, and is usually observed as a high value. Therefore, the pendulum 4 is designed for vibration components of n≧3.

For example, if Rlr is selected to satisfy 9=R/r for n=3, the radius of rotation R must be increased, but increasing R means that the flyboil 2
This means increasing the size of R, and it is difficult to increase R due to space limitations. In that case, it would be better to make r smaller, but since r is the distance from the fulcrum (point B) of the centrifugal pendulum 4 to the center of gravity G, it becomes impossible to attach a pendulum with a large mass.

Since n = 3 already has such a design difficulty, it should be ignored for n ≧ 4. Therefore, an example where this centrifugal pendulum 4 is installed in a normal multi-cylinder engine Even so, it can be said that as long as n≧3 is the target, there remains a problem.

However, in the present invention, the centrifugal pendulum 4 is applied not when n≧3 but when n=1 to 2.

That is, as mentioned above, the problems during partial cylinder operation are: (1) For a four-cylinder engine that does not replenish intake air (or exhaust air) to the cylinder on the idle side during shutdown, the primary component after transition to partial cylinder operation; (2) Intake (or 1
) 1st air), the primary component or secondary component after transition to partial cylinder operation for a 4-cylinder engine replenishing 1 air), (3) 6 cylinder 1
1 after transition to partial cylinder operation with half cylinders for Ikoseki
．． (The fifth-order component is a low-order component of n=1 to 2, and the vibrations that occur after the transition to partial cylinder operation are both components.

Specifically, in the case of (1), 1 = R/r, in the case of (2>, 4 = R/r, and in the case of (3), 2.25-R/r
Select R11' so that. This J: Una R, r
It is easy to attach the centrifugal pendulum 4 to , and FIG. 3 shows the case where 1 = R/r.

Furthermore, the reason why such centrifugal force pendulums 4 are provided every 120 degrees is to reduce all vibrations in a plane in a well-balanced manner.

Therefore, with the above configuration, in a normal multi-cylinder engine, when all cylinders are operated, the centrifugal pendulum 4
However, when shifting to partial cylinder operation in a light load range, the centrifugal pendulum 4 significantly reduces the low-order vibration components newly generated in this state. At this time, the centrifugal pendulum 4- acts as an infinitely large inertial mass with respect to the target vibration component, and acts as a finite mass with respect to other vibration components, while also acting as a finite mass against fluctuations in engine speed. Since the vibrations are absorbed by following the vibration, there is no deterioration in acceleration performance or deterioration in fuel efficiency that would occur if the measures were taken only to avoid increasing the inertial mass of the flywheel 2.

In addition, in Fig. 3, the centrifugal pendulum 4 is attached to the flywheel 2 (
=I, but it may also be attached to a rotating shaft that is synchronized with the engine main shaft.

(Effects of the Invention) As described above, according to the present invention, a resonant centrifugal force that absorbs low-order vibration components in a plane perpendicular to the main shaft of a multi-cylinder engine that performs partial cylinder operation or a rotating shaft synchronized with the main shaft is provided. Since the pendulum is provided, it is possible to significantly reduce vibrations that occur during partial cylinder operation.

[Brief explanation of the drawing]

FIG. 1 is an acupressure diagram showing changes in the cylinder pressures of the active side air 9 and the idle side cylinders of a conventional in-line four-cylinder engine, and FIG. 2 is a diagram showing the composite torque characteristics. FIG. 3 is a front view of one embodiment of the present invention, and FIG. 4 is a third XX sectional view. 1... Main shaft, 2... Flywheel, 3... Plane,
4...Resonant centrifugal pendulum. Patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Claims] Of n'=R/l゛, the harmonic vibration order 0 is 1~≦