JP2002317647A - Vibration restraining mechanism for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To install an elastic body without looseness at a low cost in a vibration restraining mechanism for an internal combustion engine having the elastic body intervened in a driving force transmission mechanism. SOLUTION: Two spiral springs 34 and 35 to which initial displacement (size θ) is applied respectively are installed as elastic bodies. The initial displacement of the one spiral spring is applied to the opposite direction from the initial displacement of the other spiral spring. Thus, the respective spiral springs are preloaded to the opposite directions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration suppressing mechanism for an internal combustion engine, and more particularly, to a driving force transmitting mechanism for transmitting a rotational driving force from a crankshaft using a vibration system formed with an elastic body interposed therebetween. The present invention relates to a vibration suppressing mechanism for an internal combustion engine that performs vibration.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. H11-3251 discloses an example of a technique for suppressing roll vibration caused by engine operation.
No. 86 is disclosed. In this case, apart from the flywheel, a secondary mass inertia body that rotates in the rotation direction of the crankshaft or in the opposite direction is provided. Then, by connecting the crankshaft and the secondary mass inertia body via the elastic body, a vibration system including the flywheel and the secondary mass inertia body is formed. Then, it is adjusted so that anti-resonance of the vibration system against the roll vibration (a state in which the vibration level becomes extremely small or becomes zero) occurs in a desired operation region.

[0003]

In such a vibration suppression mechanism due to anti-resonance, it is conceivable to use a rotating mass of an alternator (including a rotor, the same applies hereinafter) as a sub-inertial mass body. Then, for example, a spiral spring is mounted between the drive shaft of the alternator and the pulley, and an elastic body is provided to the drive force transmission mechanism.

[0004] In such a configuration, the adjustment of the vibration system is easy, but there is the following problem in terms of noise. That is, when the spiral spring is mounted between the drive shaft and the pulley (normally, the spring is mounted by inserting the spring end into a groove or a slit formed in the drive shaft or the pulley). Since a backlash (small gap) remains at the connection portion, a tapping sound is generated between them at the time of occurrence of anti-resonance, and the noise is greatly deteriorated.

[0005] This problem can be improved by inserting a member such as a shim into the connection portion to fill the play. However, in consideration of manufacturing variations in the spiral spring, the drive shaft, and the pulley, it is difficult to remove backlash in all products with a shim having one specified dimension. Also, in order to deal with such variations individually,
There is a drawback in that shims of several sizes must be prepared, which significantly increases the manufacturing cost.

Therefore, the present invention improves the mounting form of the elastic body so that even if the play is left as described above, the quietness can be maintained, and individual measures are not required, thereby reducing the cost. Another object of the present invention is to provide an excellent vibration suppression mechanism for an internal combustion engine.

[0007]

According to a first aspect of the present invention, there is provided a vibration suppressing mechanism for an internal combustion engine, comprising: a driving force transmitting mechanism for transmitting a rotational driving force from a crankshaft coupled to a flywheel; A vibration system is formed including an auxiliary mass inertia body coupled to the driven side of the driving force transmission mechanism with a body interposed therebetween, and generates anti-resonance of the vibration system with respect to a predetermined vibration input accompanying engine operation. A vibration suppression mechanism for an internal combustion engine that suppresses vibration by causing the elastic body to include a pair of elastic elements that are attached to each other with initial displacement and that connect rotating elements to each other in the driving force transmission mechanism. It is characterized in that one elastic element generates an initial torque for each rotating element in the opposite direction to the other elastic element.

According to a second aspect of the present invention, there is provided a vibration suppression mechanism for an internal combustion engine, wherein the pair of elastic elements connect rotating elements arranged concentrically. According to a third aspect of the present invention, in the vibration suppressing mechanism for an internal combustion engine, the pair of elastic elements are a pair of torsion springs. A vibration suppression mechanism for an internal combustion engine according to a fourth aspect of the present invention is characterized in that the pair of elastic elements are constituted by two spiral springs of substantially the same shape, one of which is mounted in an inverted manner.

According to a fifth aspect of the present invention, there is provided a vibration suppressing mechanism for an internal combustion engine, wherein the pair of elastic elements extend in the same direction and spirally from a central portion toward each end, and alternately on each side. , And is constituted by an integral double spiral spring. According to a sixth aspect of the present invention, in the vibration suppressing mechanism for an internal combustion engine, each initial displacement of the pair of elastic elements is larger than one amplitude of a relative angular displacement between the rotating elements at the time of occurrence of resonance. .

According to a seventh aspect of the present invention, in the vibration suppressing mechanism for an internal combustion engine, each initial displacement of the pair of elastic elements is larger than one amplitude of a relative angular displacement between the rotating elements when anti-resonance occurs. It is characterized by. In the vibration suppression mechanism for an internal combustion engine according to claim 8, the pair of elastic elements connect between a drive shaft of an alternator and a transmission vehicle to which rotational driving force is transmitted from the crankshaft. It is characterized by.

A vibration suppression mechanism for an internal combustion engine according to a ninth aspect of the present invention is characterized in that the pair of elastic elements are detachable from both the rotating elements.

[0012]

According to the first aspect of the present invention, a pair of elastic elements are preloaded on the basis of the initial displacement given to each of the elastic elements, and one of the elastic elements is attached to the other of the rotating elements with respect to the other. Is pressed in a direction opposite to the elastic element. For this reason, even if there is a dimensional difference in the connection between the elastic element and the rotating element, rattling can be eliminated by the elastic element itself without using a special member such as a shim.

According to the second aspect of the present invention, the elastic element is arranged between the concentrically arranged rotating elements, so that the elastic element mounting portion can be made compact. According to the third aspect of the present invention, the structure of the elastic body is simplified by using a torsion spring as the elastic element. According to the fourth aspect of the present invention, the backlash can be reduced at low cost by using one kind of spiral spring having substantially the same shape.

According to the fifth aspect of the present invention, a pair of elastic elements can be formed with a small number of parts by using one spring member (double spiral spring). In addition, since the space for mounting the elastic element can be narrowed, the layout is improved. According to the sixth aspect of the invention, even when resonance occurs in which the relative angular displacement between the rotating elements is maximized, all the elastic elements maintain the initial torque, that is, at least a part of the preload. Therefore, rattling can be prevented over all operating states.

According to the seventh aspect of the present invention, the preload can be maintained under anti-resonance, which occurs most frequently, to prevent rattling. Here, since the set initial displacement is relatively small, the stress at the time of mounting can be relaxed and the durability can be increased. According to the eighth aspect of the present invention, since the rotating mass of the alternator can be used as at least a part of the secondary mass inertial body, a compact vibration system can be configured.

According to the ninth aspect of the present invention, the elastic element can be replaced, and the elastic element mounting portion can be configured very simply.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention.
1A shows a configuration of a vibration suppression mechanism of an internal combustion engine (engine 100) according to the embodiment, and FIG.
FIG. 1B is a front view as viewed from the front, and FIG. 1B is a side view.

The engine 100 is a four-cylinder engine for an automobile, and the driving force of the alternator 1 is transmitted from a crankshaft (not shown) via an accessory drive belt (V-ribbed belt) 5. At the end of the crankshaft, a flyhole 1
The driven pulley (hereinafter referred to as alternator pulley) 3 provided in the alternator 1 rotates in the same direction as a driving pulley (hereinafter referred to as crank pulley) 7 on the crankshaft. The rotation direction of the alternator pulley 3 is
The direction of the belt 5 may be changed so that the direction is opposite to that of the crank pulley 7.

FIG. 2 is a sectional view showing in detail the structure of the power converter of the alternator 1. As shown in FIG. Here, the accessory drive belt 5
Is converted into rotational motion of the drive shaft 11 and transmitted to a rotor (not shown) of the alternator 1. The alternator pulley 3 includes an inner peripheral portion 31 and an outer peripheral portion 33.
These parts are divided into the drive shaft 11
It is arranged concentrically around the center. The inner peripheral portion 31 is integrally connected to the drive shaft 11, and the outer peripheral portion 33 is rotatably supported on the inner peripheral portion 31 via bearings 32 a and 32 b, and has an accessory drive belt (see FIG. Not shown)
5 are wound. The inner peripheral portion 31 and the outer peripheral portion 33 are connected by metal spiral springs 34 and 35.

The male screw portion 1 is provided at the tip of the drive shaft 11.
A stopper 1a and a washer 37 are fitted into the hole 1a, and the inner peripheral portion 31 and the drive shaft 11 are fixed by tightening a nut 38 from outside thereof. FIG. 3 is a cross-sectional view taken along the line AA of FIG. 2, and shows the mounted state of the spiral springs 34 and 35.
FIG. 4 is a perspective view of the distal end of the alternator 1 showing the mounted state, and a part thereof is a cross section.

In the present embodiment, as a pair of elastic elements,
Two spiral springs 34 and 35 having substantially the same shape (same spring constant) (here, they form a flat spiral but may be coiled) are used. These spiral springs are arranged coaxially with the vortex turned in the opposite direction so that the vortex faces in the opposite direction, and the straight portions 34a and 35a hitting the center of the vortex.
Is inserted into a slit S1 formed in the axial direction from the distal end of the drive shaft 11 and the inner peripheral portion 31.

On the other hand, the spring end outside the vortex is warped in a direction opposite to the direction of the vortex. Then, the curved portions 34b and 35b forming this rebound are connected to the outer peripheral portion 3.
3 is inserted into the slit S2 formed in the third. In the present embodiment, the slits S1 and S2 are formed on a straight line perpendicular to the drive shaft 11. Here, the spiral spring 34,
In a natural state where only one end is inserted into the slit S1, each curved portion is at a position indicated by 34 'or 35' in FIG. These positions form an angle θ in the opposite direction from the center of the slit S2 around the drive shaft 11. And from this natural state, each spiral spring,
An angular displacement is given to the position of the slit S2 and the slit S
Inserted into 2.

Therefore, in the mounted state in which the spiral springs 34 and 35 are also inserted into the slit S2, these spiral springs are given an initial displacement θ. For this reason, an initial torque corresponding to the initial displacement θ is generated, pressed against the inner wall forming the slit S1 and the inner wall forming the slit S2, and locked. Since the directions of these initial torques are opposite, and the spring constants of both spiral springs are the same, the initial torques of the spiral springs are balanced.

Since the spiral springs 34 and 35 are interposed in the driving force transmission mechanism in this manner, the drive force transmission mechanism is constituted by the inertia mass of the main flywheel system including the flywheel 10 attached to the crankshaft, and the rotating mass inside the alternator 1. A vibration system is formed by the auxiliary inertial mass body, the spiral springs 34 and 35 as elastic bodies, and the accessory drive belt 5. The resonance frequency f0 of this vibration system is represented by the following equation (1). Also,
With respect to the vibration input to this system due to the roll vibration of the engine 100 and the fluctuation of the engine rotation, anti-resonance occurs at the anti-resonance frequencies f1 and f2 shown in the following formula (2) or (3) with resonance.

[0025]

(Equation 1)

Where f0: resonance frequency f1: anti-resonance frequency against engine roll vibration f2: anti-resonance frequency against engine rotation fluctuation I1: inertia moment of main flywheel system inertia mass I2: inertia moment of sub inertia mass ρ: alternator increase Speed ratio (ρ> 0 when driven in the engine rotation direction, ρ <0 when driven in the opposite direction to the engine rotation direction) K: Spring coefficient (here, auxiliary drive belt and 2 These anti-resonance frequencies f1 and f2 are used when the engine 100 is frequently used and operated at a substantially constant rotation in the operating state of the engine 100. By setting them together, in such an operating state, an excellent effect of suppressing vibrations based on various excitation inputs can be obtained. FIG. 5 shows an example of the effect.

Such an operating state is, for example, an idling time in a normal automobile engine. For example, in the case of a four-cylinder engine, fluctuations in the combustion pressure cause vibration components of engine rotational speeds of 2, 4, 6... . In the case of a six-cylinder engine, the tertiary frequency is particularly problematic, and in the case of an eight-cylinder engine, the tertiary frequency is particularly problematic.

Therefore, if the idling rotational speed of the engine 100 (four cylinders) is 750 rpm, the above equation (2) is set so that the antiresonant frequency f1 or f2 coincides with the secondary rotational frequency (25 Hz). ) Or (3)
, The spring constants of the spiral springs 34 and 35, the inertia moment of the rotor of the alternator, the speed increase ratio ρ, and the like are adjusted.

With such a setting, the excellent vibration damping characteristics of the vibration suppressing mechanism against the roll vibration or the rotation fluctuation of the engine 100 at the time of idling can be exhibited. In addition,
The problem of the roll vibration of the engine 100 at the time of idling is that the automatic transmission (A / T) is in the N range of a car or the manual transmission (M /
T) A low load state where the driving load of the auxiliary equipment of the car is small. On the other hand, the rotation fluctuation becomes a problem at the time of idling at the time of the D range of the A / T vehicle or at the time of the high load at which the auxiliary equipment driving load of the M / T vehicle is large.

As described above, the two spiral springs 3
Giving the initial displacement θ to 4 and 35 has the following advantages. First, in the stationary state, the slit S1 or S1
Even if the width of 2 is large and there is a dimensional gap between the slit wall surface and the end of the spring, rattling can be suppressed because the preload acts on these spiral springs.

When resonance occurs, the maximum half-amplitude (half-amplitude = amplitude / 2) θ0 between the inner peripheral portion 31 and the outer peripheral portion 33 is obtained.
Relative angular displacement occurs. On the other hand, in the present embodiment,
The initial displacement θ of the spiral springs 34 and 35 is the above θ
It is set larger than 0. Therefore, the torque generated by any of the spiral springs does not become zero at the time of occurrence of resonance, and the load for pushing the spring end against the slit wall surface is maintained even at the time of the maximum angular displacement under resonance, so that a tapping sound is generated. Can be prevented.

FIG. 6 shows the engine radiation noise at the time of occurrence of resonance, comparing the engine according to the present embodiment with the conventional one. As described above, according to the present embodiment, it can be seen that the noise is reduced in a wide frequency band. Under anti-resonance, the relative angular displacement between the inner peripheral portion 31 and the outer peripheral portion 33 is smaller than in the case of resonance. Sound generation can be prevented.

Next, a second embodiment of the present invention will be described. FIG. 7 is a cross-sectional view partially showing the structure of the power conversion unit of the alternator according to the present embodiment, and corresponds to FIG. 3 in the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. First, as a characteristic configuration, in the present embodiment, one double spiral spring 41 is used as an elastic body.

The double spiral spring 41 is a single spring material (wire or plate) having a substantially circular cross section or a substantially rectangular cross section.
Is formed in a spiral shape in the same direction from both ends of the straight portion, leaving a straight portion 41a of a predetermined length at the center, thereby forming two spring portions 41 overlapping each other in a plane.
b, 41c. In addition, the end of each spring portion is warped in the direction opposite to the spiral direction, so that the curved portion 4 is formed.
1d and 41e are provided.

In such a double spiral spring 41, the central straight portion 41a is inserted into the drive shaft 11 of the alternator and the slit S1 formed in the inner peripheral portion 31 of the alternator pulley, and the curved portions 41d and 41e are formed. The outer peripheral portion 33 of the alternator pulley is inserted into slits S2 and S2 formed axially symmetrically. Also in this case, the curved portions 41d and 41e of the double spiral spring are at positions (41 ') which are shifted from the corresponding slit S2 in the natural state by an angle θ in the opposite direction about the drive shaft 11 in the natural state.
An initial displacement θ from there to the slit position is given.
The initial displacements θ have the same magnitude but opposite directions, so that the two spring portions 41b and 41c in the mounted state generate initial torques of the same magnitude in opposite directions. The double spiral spring 41 is made of an integral spring material. Since the spring constants of the spring portions are equal, the initial torque generated by these spring portions in the mounted state is balanced.

By adopting such a configuration, the engine vibration can be suppressed while preventing rattling over the entire operation range, as in the first embodiment.
Further, in the present embodiment, since the pair of elastic elements is constituted by the respective spring portions of one double spiral spring 41, the number of components is reduced, and the overall length (dimension in the front-rear direction) of the alternator pulley is reduced. It is also possible.

In the above description, an example has been shown in which the initial displacement θ of the elastic element is set to be larger than this in accordance with the half amplitude θ0 at the time of resonance. However, the present invention is not limited to this, and the initial displacement θ can be set appropriately. For example, the initial displacement θ may be set according to the half amplitude θ1 at the time of occurrence of anti-resonance (θ> θ1).

According to such a setting, rattling can be prevented under anti-resonance, which occurs most frequently. In this case, a tapping sound may be generated at the time of occurrence of resonance. However, in actual operation, the occurrence of resonance is almost instantaneous, so this is not a serious problem. Rather, since the initial displacement θ is relatively small, the stress at the time of mounting the spring is relieved, and there is a great advantage that a margin can be provided in terms of durability.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a vibration suppression mechanism of an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a sectional view of an alternator pulley provided in the internal combustion engine and a mounting structure thereof.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a perspective view showing an example of an elastic element mounted state.

FIG. 5 is a diagram showing an example of the effect of the vibration suppression mechanism of the internal combustion engine according to the present invention.

FIG. 6 is a diagram showing an example of a noise reduction effect according to the present invention.

FIG. 7 is a cross-sectional view showing another example of an elastic element mounted state.

[Description of Signs] 1 ... Alternator 11 ... Drive shaft 3 ... Alternator pulley 31 ... Pulley inner circumference 32 ... Bearing 33 ... Pulley outer circumference 34, 35 ... Spiral spring 41 ... Double spiral spring 5 ... Auxiliary drive belt 7 ... Crank pulley 10 ... Flywheel 100 ... Engine S1, S2 ... Slit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuyuki Asahara 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Prefecture Inside Nissan Motor Co., Ltd. In-house F term (reference) 3G093 AA16 BA32 BA33 CA08 DA01 DB26 EA03

Claims (9)

[Claims] 1. A driving force transmitting mechanism for transmitting a rotational driving force from a crankshaft coupled to a flywheel, including a secondary mass inertia member coupled to a driven side of the driving force transmitting mechanism via an elastic body. A vibration suppression mechanism for an internal combustion engine that forms a vibration system and suppresses vibration by generating anti-resonance of the vibration system with respect to a predetermined vibration input accompanying engine operation, wherein the elastic bodies each have an initial state. The driving force transmission mechanism is configured to include a pair of elastic elements that are attached by applying a displacement and connect the rotating elements to each other. One elastic element has a direction opposite to that of the other elastic element with respect to each rotating element. A vibration suppression mechanism for an internal combustion engine, which generates an initial torque. 2. The vibration suppressing mechanism for an internal combustion engine according to claim 1, wherein said pair of elastic elements connect concentrically arranged rotating elements. 3. The vibration suppressing mechanism for an internal combustion engine according to claim 2, wherein said pair of elastic elements are a pair of torsion springs. 4. The vibration suppression mechanism for an internal combustion engine according to claim 3, wherein said pair of elastic elements are constituted by two spiral springs having substantially the same shape and mounted one by one. 5. The pair of elastic elements are constituted by an integral double spiral spring, which extends in the same direction and helically from the central portion to each end portion in the same direction and alternately overlaps on each side. The mechanism for suppressing vibration of an internal combustion engine according to claim 3, wherein: 6. The apparatus according to claim 3, wherein each initial displacement of said pair of elastic elements is larger than one amplitude of a relative angular displacement between said rotating elements at the time of occurrence of resonance. Vibration suppression mechanism of internal combustion engine. 7. The method according to claim 3, wherein each initial displacement of said pair of elastic elements is larger than one amplitude of a relative angular displacement between said rotating elements when anti-resonance occurs.
The vibration suppression mechanism for an internal combustion engine according to any one of the first to third aspects. 8. The apparatus according to claim 1, wherein said pair of elastic elements connect between a drive shaft of an alternator and a transmission vehicle to which rotational driving force is transmitted from said crankshaft. A vibration suppression mechanism for an internal combustion engine according to one of the above aspects. 9. The apparatus according to claim 1, wherein said pair of elastic elements are detachable from both of said rotating elements.
8. The vibration suppression mechanism for an internal combustion engine according to any one of 8.