JPH04102744A - Vibration reducing device for internal combustion engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a vibration reduction device for reducing vibrations caused by unbalanced components of the rotational second order of an internal combustion engine.

Conventional Technology For example, in an in-line four-cylinder internal combustion engine, vibrations due to unbalanced components of the second order of rotation become noticeable, so a balancer shaft having an eccentric counterweight portion is provided parallel to the crankshaft, and the balancer shaft is A balancer shaft mechanism is conventionally known in which the excitation force of the internal combustion engine itself and the excitation force of the balancer shaft are rotated synchronously with each other to cancel each other out (Japanese Patent Laid-Open No. 62-204.069, etc.). reference).

FIG. 3 shows an example of this conventional balancer shaft mechanism, in which a pair of balancer shafts 31 are arranged parallel to each other on both sides of a crankshaft (not shown). This balancer shaft 31 consists of a shaft portion 34a with a perfect circular cross section and a counterweight 31b with a semicircular cross section having the same center as the shaft portion 31a, and journal portions 3Lc formed at multiple locations support the bearing of the cylinder block. A sprocket 32 is attached to the end of one balancer shaft 31, which is fitted into a hole (not shown) and is rotatably supported, and the other balancer shaft 31 is connected to the sprocket 32 through gears 33, 34. sprocket 35
A timing belt 37 is wound between the crank sprocket 36 and both sprockets 32 and 35. As a result, both balancer shafts 31 rotate in opposite directions and at twice the speed of the crankshaft.

Problems to be Solved by the Inventionj7 If a balancer shaft mechanism as described above is provided to reduce secondary rotational vibrations of an internal combustion engine, the size of the cylinder block will increase accordingly, leading to an increase in the weight of the internal combustion engine. There is a problem that the fuel consumption rate worsens due to the drive of the engine.

Means for Solving the Problems Therefore, the present invention aims to reduce secondary rotational vibrations by using an alternator, which is a type of auxiliary equipment for an internal combustion engine, as a balancer shirt. That is, the vibration reduction device for an internal combustion engine according to the present invention incorporates an alternator in a part of the side wall of a cylinder block, gives a predetermined rotational unbalance to the rotor of the alternator, and has a rotor that is twice as large as the crankshaft. It is characterized by being configured to rotate at a speed of .

Function In the above configuration, either the alternator rotor or the crankshaft
Rotating at twice the speed generates a rotational secondary excitation force, which cancels out the rotational secondary component of the internal combustion engine itself.

Embodiment FIG. 1 shows a first embodiment of the present invention, in which an alternator case portion 2 is formed in a bulging part on a side wall of a cylinder block 1 of an internal combustion engine, and an alternator 3 is built therein. has been done.

The alternator 3 is roughly divided into a stator 4 consisting of a stator core 5 and a stator coil 6 fixed to the alternator case portion 2, and a rotor 8 that rotates integrally with a rotor shaft 7. The rotor 8 includes a pair of ball cores 9 arranged to mesh with each other, a field coil 10 and a core 11 housed therein, and a fan 12 for introducing cooling air arranged in front of the ball cores 9.
and an internal fin 13 arranged behind the ball core 9. In addition, a pulley 14 is fixed to the front end of the rotor shaft 7, and a belt 15 is wound between the pulley 14 and a crank boot (not shown).
．． It rotates at twice the speed of the crankshaft.

The rotor 8 has a predetermined amount of rotational imbalance. In other words, when divided into 180' sections in the circumferential direction,
One mass is large and the other mass is small.

This means, for example, that parts of each member are made of materials with different specific masses.1. This can be achieved by providing a hollowed out part.

Further, both ends of the rotor 8 are supported by the alternator case portion 2 not by rolling bearings but by metal bearings 16 and 17 in order to sufficiently support the excitation force generated here. Although not shown in detail, the alternator case section 2 is partially removable for assembling the rotor 8, etc., and has slits for passing cooling air as appropriate. The installation number is listed.

Further, a water jacket 18 is formed near the alternator case portion 2 of the cylinder block 1, through which engine cooling water flows to cool the alternator 3. Thereby, the alternator 3 is reliably cooled and its temperature rise is suppressed.

Now, in the above configuration, the rotor 8 of the alternator 3
rotates at twice the speed of the crankshaft and generates a rotational secondary vibrational force, thereby canceling out the rotational secondary vibration component generated by the internal combustion engine itself. (7) According to this configuration, there is not much difference in terms of space compared to when the alternator is attached to the cylinder block as an independent auxiliary device.
Moreover, there is no significant increase in weight. Zunawaji allows the balancer shaft to perform its functions without requiring the addition of any new parts. Furthermore, since there is no need to drive an extra balancer shaft, it is also advantageous in terms of fuel consumption.

Next, a second embodiment shown in FIG. 2 is an example in which a permanent magnet 21 is used in place of the ball core 9 and field coil 10 of the rotor 8.
It is molded into 2. Therefore, the mass of the permanent magnet 21 is different between one side and the other side divided in the circumferential direction 180', and has a predetermined amount of rotational imbalance. This can be achieved, for example, by forming the permanent magnets 21 in each direction from materials with different specific masses, or by changing the size of the permanent magnets 21, but in the latter case, materials with different magnetic flux densities are used. , it is desirable to generate substantially equal magnetic fields in each direction.

Effects of the Invention As is clear from the above explanation, according to the vibration reduction device for an internal combustion engine according to the present invention, the rotor of the alternator is used as a kind of balancer shaft to offset secondary rotational vibrations, so that the internal combustion engine Vibration reduction can be achieved without increasing the size, weight, or number of parts. Further, unlike the case where a balancer shaft is provided as a separate member, there is no increase in friction or deterioration in fuel consumption rate.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a first embodiment of a vibration reduction device according to the present invention, FIG. 2 is a sectional view showing a second embodiment, and FIG. 3 is a perspective view showing a conventional balancer shaft mechanism. 2...Alternator case part, 3...Alternator,
8. Rotor. Figure 2 Figure 3 2-111 rotor case 3--1000 rotor

Claims (1)

[Claims] (1) An alternator is built into a part of the side wall of the cylinder block, and a predetermined amount of rotational imbalance is applied to the rotor of this alternator.
A vibration reduction device for an internal combustion engine, characterized in that it is configured to rotate at twice the speed.