JPH0333534A - Vibration removing device for engine - Google Patents

Abstract

PURPOSE:To effectively remove complicated unbalance vibration by reciprocatably fitting a balance weight to an engine body, and fitting a drive means to reciprocate the balance weight, interlocking with a crankshaft. CONSTITUTION:A vibration removing device 1 is pivotally supported on a fitting shaft 4 fixed on a bracket 2 mounted on an engine. A rocker arm 8 having a balance weight 6 fitted on its extreme end and a cam 10 driving the rocker arm 8 are provided. The cam 10 is engaged with the guide hole 16 formed on the rocker arm 8 to reciprocate the balance weight 6. Even against a vibration of which vector of the moment of inertia does not draw an elliptical locus, it can deal with. In this way, complicated unbalance vibration can be effectively removed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine vibration removal device, and more particularly to a vibration removal device suitable for removing vibrations caused by secondary imbalance of an engine.

[Conventional technology]

In a reciprocating engine, vibrations occur in the engine due to the reciprocating motion of the piston, and conventionally a balance weight has been attached to the crankshaft to reduce vibrations caused by eccentric rotation of the large end of the connecting rod. By the way, the inertia force output by one cylinder is the crankshaft rotation angle θ
A function whose parameters are (A cos θ+B cos
2θ+...), and the vibration caused by the reciprocating motion of the piston includes, in addition to the primary vibration whose component is the rotational angular velocity of the engine, vibration due to a component rotating at twice the angular velocity. Vibrations due to higher-order rotational components can generally be ignored. Furthermore, depending on the type of engine, such as an inline engine or a V-type engine, the vibration appears as a vibration having a specific inertial force or moment of inertia. Therefore, a balance weight that rotates at the same rotation speed as the crank is effective in reducing vibrations based on cos θ, that is, primary vibrations, but is not effective at all in reducing vibrations based on cos 2θ, that is, secondary vibrations. It has long been known that there is no such thing.

For example, the vibrations that occur in a type 6-cylinder engine are the residual vibration synchronized with the rotational speed of the crankshaft, that is, the primary residual vibration moment, and the vibration that has a phase that rotates at twice the previous rotational speed, that is, the secondary vibration. A residual unbalance moment is added.

In order to remove the secondary residual unbalance moment, for example, in the case of a V-type engine, a balance weight that rotates eccentrically between cylinders arranged in two rows in a ■ shape (hereinafter, a device using this balance weight is called a rotating balancer) is used. )
It is common practice to provide a rotary balancer and rotate the rotational balance at a rotational speed twice the rotational speed of the crankshaft.

However, since the balance weight is provided eccentrically with respect to the rotating shaft of the crankshaft, which is a vibration source, there is a problem in that new vibrations, such as vertical vibrations, are introduced.

Therefore, the invention disclosed in Japanese Patent Application Laid-Open No. 59-121237 is that, in a V8 engine with a bank angle of 90 degrees, the rotational balancer that rotates at double speed is placed equidistantly above and below and front and back across the center of gravity of the engine. This is to prevent new vibrations from occurring due to eccentricity.

[Problem to be solved by the invention]

By the way, the configuration in which rotary balancers are provided at two locations in order to eliminate secondary residual vibrations as disclosed in the above-mentioned publication has a problem in that the structure is complicated. Furthermore, there is a problem in that the secondary residual unbalance moment has a vibration mode that cannot be removed by the balance weight rotating at twice the rotational speed of the crankshaft.

Hereinafter, the characteristics of primary residual vibration and secondary residual vibration for a V6 engine will be explained based on Table 1.

(Margins below this page) Crank Sun n-6s [1-5s I]-6 Slow explosion interval 120' 120° 120° Due to mass Moment pitching 1st order O → Increased calories → 0.45
MB pitching secondary 1.58M' → decrease → 1. IBM'(-0,3758M)*
(=0.2788 M) *Yawing primary 0 → Increased calories → 0
．． 45MB yaw ink secondary 1.5BM'
→Power increase■→ 2. IBM' (=0.3758 M
)* (-0,5258M)*,
Each symbol in Table 1 is used with the following meanings, and the parentheses indicated by the symbol * will be explained below. That is, B is the cylinder bore pitch, M = M recir ω2 M r , c = (reciprocating partial weight) = W++ Wz
, Wl is the weight of the piston, and 2 is the reciprocating weight of the connecting rod, which is usually expressed as the weight of the 1/3 portion of the connecting rod on the piston side.

r is the connecting rod radius ω is the rotational angular velocity of the connecting rod (rad,) M' = M λ As shown in Table 1, in the V6 type engine, the bank angle V is set to 60 by the balance weight attached to the crankshaft.
The first residual unbalance moment can be set to "0" when . As for each of the other residual unbalance moments, as the bank angle V increases from 60°, the primary residual unbalance moment increases for both pitching (vertical vibration) and yawing (lateral vibration), and the secondary residual unbalance moment increases. It can be seen that the residual unbalance moment has the characteristics that pitching and yawing decrease and increase, respectively.

And in Table ■, the first-order residual unbalance moment is M
and the second-order residual unbalance moment as a function of M'. Therefore, in order to compare the sizes of the two, convert M' into M. Since the connecting rod ratio is normally λξ4 in a practical engine, the first
As shown in the parentheses in the table, the residual unbalance moment of secondary yawing is larger than the residual unbalance moment of primary yawing, and it is important to remove the secondary residual unbalance moment. I understand.

Moreover, when the bank angle is 60°, the trajectory of the secondary residual unbalance moment becomes a circular trajectory as shown in Figure 9, and can be removed by a balance weight that rotates at twice the rotation speed of a conventional crankshaft. For example, in the case of 90 degrees, a trajectory whose size changes as shown in FIG. 10 is drawn, so it cannot be removed by the above-mentioned rotating balance weight.

The present invention has been developed by focusing on the above problems,
It is an object of the present invention to provide an engine vibration removal device that can effectively remove vibrations caused by reciprocating movement of a piston, especially unbalance caused by secondary residual unbalance moments, without generating new vibrations such as vertical vibrations. The purpose is

[Means for Solving the Problems] In order to achieve the above-mentioned object, the structure of the engine vibration removing device of the present invention is such that a balance weight is attached to the engine body so as to be able to reciprocate in a direction perpendicular to the rotation axis of the crank. A drive means is installed to move the balance weight back and forth in conjunction with the crankshaft, and this drive means is so linked as to displace the balance weight in accordance with the vibration period caused by the rotation of the crankshaft. be.

The driving means is not particularly limited, but usually a cam can be used. In addition, power transmission means such as gears and chains can be used as means for rotating the drive means at a predetermined rotation ratio in conjunction with the crankshaft.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The vibration removing device of the present invention will be specifically described below with reference to embodiments with reference to the accompanying drawings.

FIG. 1 is a front view of the essential parts of the vibration removing device of the first embodiment, and FIG. 2 is a cross-sectional view taken along the line ■--■ in FIG. In the figure, the vibration removing device 1 is fixed to a bracket 2 attached to an engine (not shown), and has a swinging arm 8 which is pivoted on a shaft 4 and has a balance weight 6 attached to its tip. There is a cam 10 to be driven. Note that 11 in the figure
is a bolt that fixes the balance weight 6 to the swing arm 8.

This cam 0 is mounted eccentrically with respect to the axis 14 of a rotating shaft 12 driven by a crankshaft (not shown). Then, the cam IO engages with a guide hole 16 formed in the swing arm 8 and causes the balance weight 6 to reciprocate. When the vibration removing device shown in FIG. 1 is arranged as shown in the figure, the balance weight 6 can be placed near the center of gravity of the engine (not shown). In order to rotate the rotary shaft 12, the speed may be changed to a predetermined rotation ratio and transmitted from a crankshaft (not shown) using a gear.

FIG. 3 shows a sectional view of a main part of the second embodiment. The balance weight 6 of the vibration removing device 1 of the second embodiment is slidably fitted into a cylinder 18 in which a return spring 17 is arranged, and the balance weight 6 can be vibrated within the cylinder 18 by the cam 10. As a modification of FIG. 3, balance weights 6 can also be arranged on both sides of the cam 10. Although FIG. 3 shows the balance weight 6 as vibrating in the horizontal direction, it may be arranged in other directions, for example, in the vertical direction, or in both the vertical and horizontal directions.

Next, a third embodiment will be described with reference to FIGS. 4 to 6. The vibration removing device of the third embodiment is a V6 type engine 20.
It was applied to In the figure, the vibration removing device shown in FIGS. 1 and 2 is placed upside down, and the rotating shaft 12 for rotating the cam 10 is equipped with a rotational balancer 22 for removing secondary vibrations, which is conventionally used. It is attached to the V-shaped bottom of the engine 20 at the center of the left and right banks by a bearing 21.

0 To rotate the rotating shaft 12, a gear train 30 (not shown in FIG. 4) connects the gear 26 provided on the crankshaft 24 and the gear 26 provided on the rotating shaft 12.
The rotating shaft 12 is configured to rotate in the opposite direction at twice the rotational speed.

As described above, the secondary residual unbalance moment of the third embodiment is determined by the vibration removal device 1 and the crankshaft 3 whose vibration speed is set to 21 times the rotational speed of the crankshaft 24 by the rotating shaft 12.
The rotary balancer 22 rotates in the opposite direction at twice the rotational speed of 6.

Next, the operation and vibration removal effect of the third embodiment will be explained. The moment of inertia M ro c i of the engine due to the rotation of the crankshaft 24 of the V6 engine 20 is expressed as (] where the component in the X-axis direction is MX and the component in the Y-axis direction is MY
) and (2).

However, the relationship between the symbols and the engine is shown in FIGS. 5 and 6. That is, MX= 38 M'5in-cos2 (θ-60°
)-Xcos2 (θ-60°) (1) ■ M, = J 3 B M'cos-sin 2 (θ-6
0°) - Ysin2 (θ - 60°) (2) θ in the equation is 511 degrees, which indicates the rotational position of the crank, and as shown in Figure 6, the pair of cylinders #1 and #4 (piston only The intermediate position of each crank pin 32, 34 (as shown) is defined by the angle it makes with the Y axis. β is the angle between crank arms a and C,
When the bank angle is 60° to 90°, x>Y holds true. Also 36
is a balun weight provided on the crankshaft 12 for primary vibration.

(+), Equation (2) shows that when the crank angle θ defined above rotates clockwise at an angular velocity ωrad, the secondary residual unbalance moment M r , ci is 2(θ−6(1
'), that is, it rotates counterclockwise at an angular velocity of 2ω. Now, by adding Ysin2(θ-60°) (3) to (2)2, MV=O, and the rotational balancer 222 can reduce the longitudinal vibration of the engine due to the residual second-order moment to zero. In that case, the horizontal residual 2
The next component is MX=XCO52(θ-60°)-Ycos2(θ-
60°) (4).

In order to find the relationship between the rotation angle θ of the crankshaft 12 and the phase of the rotation balancer 22, θ=
Substituting 0 gives M x (θ=60°) = 0.5 Y
(3)'M v (θ-60°) = 0.866Y
(4)' is obtained. This relationship holds true when the crankshaft 24 is arranged at θ-〇° as shown in
This indicates that the rotational balancer 22 should be installed in the 0° direction. This horizontal residual moment of inertia is L
If XO, then from equations (1) and (2), LX, -(X
-Y) cos2(θ-60°) (5),
It can be seen that the cam 10 should be rotated so that the balance weight 6 vibrates based on equation (5).

The above results are summarized using a 3℃ class V6 engine 3 (V=80°, r ``140mm, Mrec+''
;100g, B = 10cm) for 6000r
When determining the specifications under the condition of pm, x=54.
3kg, Y=37.4kl+ is obtained from equation (2).

From the above, the secondary imbalance is an elliptical orbit with a major axis of 54.3 kg and a minor axis of 37.4 kg, and a crank angle θ of 0 to 360.
It generates vibration that rotates twice while rotating at 1°. this,
The vibration removing device shown in Fig. 1 for eliminating vibrations (however, the state installed on the engine is reversed as shown in Fig. 4) is as follows: Distance between shaft 4 and shaft center 14: 50 mm Distance between shaft 4 and screw 11 Distance: 80 mm Mass of balance weight 6: 66 g Eccentric distance from shaft center 14 of cam 10: 4.3 mm By hanging, residual secondary vibrations could be effectively removed.

〔Effect of the invention〕

As explained above, since the vibration removing device of the present invention is configured as explained above, the following effects can be obtained.

4 4゜ Conventionally, balance weights that remove vibrations caused by engine crank rotation were rotated in synchronization with the vibration cycle, but by using a vibration removal device that vibrates reciprocatingly, Since it is possible to cope with vibrations in which the hector of inertia does not follow a circular trajectory, complex unbalanced vibrations can be effectively removed.

In particular, when combined with a conventional rotational balancer, the secondary unbalanced vibrations of the ■-type engine can be effectively eliminated.

[Brief explanation of drawings]

FIG. 1 is a front view of the main parts of the vibration removing device according to the first embodiment;
Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1, Fig. 3 is a sectional view of the main part of the vibration removal device according to the second embodiment, and Fig. 4 is a combination with a rotational balancer to remove secondary unbalanced vibrations. A front view of the vibration removing device according to the third embodiment, FIG. 5 is a partially cutaway side view of FIG. 4, and FIGS. 6 to 7 explain the symbols used in the formulas related to the third embodiment 5. An explanatory diagram for this purpose, Fig. 8. An explanatory diagram for the installation of the rotational balancer of the third embodiment.
FIG. 0 is a graph showing the second-order moment of inertia locus of a V6 engine with a bank angle of 90°. l...Vibration removal device, 6...Balance weight, 8
... Swinging arm, 10... Cam, 12... Rotating shaft, 1
6... Guide hole, 17... Return spring, 1 day...
...Cylinder, 20...V6 type engine, 22...
Rotating balancer, 24...crankshaft.

Claims (1)

[Claims] A balance weight is attached to the engine body so as to be able to reciprocate in a direction perpendicular to the rotational axis of the crank, and a drive means is attached for reciprocating the balance weight in conjunction with the crankshaft. A vibration removal device for an engine in which the balance weight is interlocked to displace the balance weight in accordance with the vibration period.