JPH059556Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to the structure of a crankshaft for an internal combustion engine.

<Prior Art> Conventional crankshafts for internal combustion engines include:
For example, there is one shown in FIG.
(See Patent Publication No. 55-30559, FIG. 10).

That is, the crankshaft body 1 is divided into a front crankshaft 2 and a rear crankshaft 3 at the center in the axial direction. The front crankshaft 2 has a shaft portion 4 and an external spline 5 formed at one end, and the rear crankshaft 3 has a bottomed hole 6 and an internal spline 7 formed at one end. , 6 rotate as one. Further, a flyhole 8 is fastened to the other end of the rear crankshaft 3 by a bolt (not shown), and rotates together with the crankshaft body 1. A ring gear 9 is provided on the outer periphery of the flyhole 8, and is driven by a starter motor (not shown) when starting the engine.

When the crankshaft main body 1 is divided in this way, the length of each divided crankshaft 2, 3 is halved, and the bending rigidity is strengthened.
Since the interlocking connection portion between the crankshafts has a relatively flexible structure, vibration transmission between the crankshafts is suppressed, and the vibration suppression effect is greater than that of an integrated crankshaft.

<Problems to be Solved by the Invention> However, even in this case, since the heavy flyhole 8 is fixed to one end of the crankshaft body 1, the following problems occur.

That is, as shown in FIG. 6, since the bearing 30 of the crankshaft body 1 closest to the flywheel 8 is provided at the end of the cylinder block, the supporting rigidity is low, and when the cylinder adjacent to the bearing is in combustion, the bearing 30 of the crankshaft body 1 is located at the end of the cylinder block. When the combustion pressure shown by is applied to the crankshaft body 1, the bearing causes a tilting deformation as shown by the arrow C, and the crankshaft main body 1 tends to be bent and deformed as shown by the dotted line.
causes a large surface runout as shown by arrow B, amplifying the bending vibration of the crankshaft.

This bending vibration of the crankshaft propagates from the engine body 31 to the power plant 32 through the bearings, as shown in FIG. There is noise inside the car when driving.

The present invention was developed in view of these conventional problems, and it is an object of the present invention to provide a crankshaft for an internal combustion engine that suppresses bending vibration of the crankshaft during engine operation, thereby reducing noise inside the vehicle. The purpose is to

<Means for Solving the Problems> For this reason, the present invention involves meshing and connecting the divided crankshafts with each other through the respective meshing portions, and also connecting the divided crankshafts with each other by meshing and connecting ends of the crankshafts facing each other. A flywheel is provided and these flywheels are connected via an insulator made of an elastic body.

<Function> In addition to improving the bending rigidity of each divided crankshaft due to its short length, the weight of each flywheel is significantly reduced, thereby further increasing the bending rigidity. Furthermore, since the flywheel is provided in the middle portion of the crankshaft body, the bearings close to the flywheel are supported from both sides, thereby reducing falling deformation and suppressing surface runout of the flywheel. In addition, by connecting the crankshafts to each other via an insulator, it is possible to tolerate slight relative torsion between the crankshafts, which allows each crankshaft to be shortened and the flywheel to be lightweight, suppressing torsional vibration. can.

From these points, the bending vibration and torsional vibration of the crankshaft can be effectively suppressed, and the noise level inside the vehicle caused by the bending vibration can be significantly reduced.

<Example> An example of the present invention will be described below with reference to FIGS. 1 to 4.

The crankshaft 10 of this embodiment is divided into a front crankshaft 11 and a rear crankshaft 12 of approximately equal length, as in the conventional case, but the ends of each crankshaft 11 and 12 on the divided side A flywheel 13 is integrally cast into each of the two. Furthermore, a serration 14 is formed at the center of the flywheel 13 portion of the front crankshaft 11. On the other hand, a protrusion 16 is formed at the center of the flywheel 13 of the rear crankshaft 12, and a spline 15 is formed at the tip of the protrusion 16. The rear crankshaft 11 and the rear crankshaft 12 connect the respective flywheels 13 so as to face each other. The clearance in the circumferential direction between the meshing portion of the spline 15 and the serration 14 is desirably set to, for example, about 0.5 degree or less in terms of angle in order to ensure accuracy of ignition timing control. On the other hand, the length of the meshing portion in the longitudinal direction of the crankshaft 10 is desirably low in order to reduce the bending direction rigidity of the meshing portion to reduce vibrations in the bending direction, and is, for example, about 5 mm or less.

A gear 17 is provided between each flywheel 13.
is provided by fitting the protrusion 16 into a mounting hole 18 formed at its center. Further, a bush 19 for determining the center position of the gear 17 is attached to the attachment hole 18.

Further, between the gear 17 and the flywheel 13, an insulator 20 is fixed in advance to the flywheel 13, for example, by baking, etc., and is fixed at several locations (for example, 3 locations in total) with bolts 22 via a collar 21. It is provided. Here, it is desirable that the collar 21 regulates the deflection of the insulator 20 to a predetermined value when the bolt 22 is tightened.

The gear 17 meshes with the main drive gear 41 of the transmission 40.

Since the gear 17 is provided in the center of the crankshaft 10, the transmission 40 is laid out in parallel with the engine 50, and the longitudinal length can be shortened. 42 is a clutch, and 43 is a gear train. With this layout configuration, both ends of the crankshaft 10 can protrude to the front and rear of the engine 50, making the layout of auxiliary equipment such as the water pump extremely easy.

Next, the action will be explained.

The divided crankshafts 11 and 12 are connected to each other by a meshing portion consisting of a serration 14 and a spline 15, so that the effect of blocking vibration transmission is large, and this improves the damping effect, as in the case of the conventional crankshaft. be.

In addition, the length of each crankshaft 11, 12 is 1/2, and the flywheel 13 provided thereon is 1/2 the length of each crankshaft 11, 12.
Since it is only necessary to pay for 12 minutes, the size and weight are significantly reduced, and the bending rigidity is greatly improved.

Furthermore, since the flywheel 13 is provided in the center of the crankshaft 10, the bearings close to each flywheel 13 are supported on both front and rear sides, which suppresses the bearings from collapsing and deformation, reducing the weight of the flywheel 13. Due to the synergistic effect of
The effect of suppressing bending vibration of No. 12 is greatly improved.

Also, in terms of the power plant as a whole, since the flywheel 13 with a large mass is disposed in the center of the crankshaft 10, the resonance of bending vibration is reduced compared to when it is disposed at the end of the crankshaft 10. The frequency can be made significantly higher, and on the other hand, the higher the frequency, the lower the level of the frequency characteristics of the combustion pressure, so it is clear that the bending vibration level of the crankshaft 10 can be greatly reduced from this point as well.

Furthermore, since the crankshafts 11 and 12 are connected to each other via the insulator 20, slight relative torsion between the crankshafts 11 and 12 is allowed, so torsional vibration can be considered for each crankshaft 11 and 12.
In this case, the length of each crankshaft 11, 12 is reduced to 1/2, and each flywheel 13 is lightweight (small moment of inertia), so the torsional rigidity is extremely high, and the effect of suppressing torsional vibration is also significant. In this respect as well, the effect of reducing engine noise and in-vehicle noise can be enhanced, and furthermore, the sound radiated from the pulley fixed to the crankshaft 10 can be significantly reduced. However, each crankshaft 1
If the relative torsion between 1 and 12 becomes too large, the ignition timing will vary between cylinders, but as mentioned above, the circumferential clearance between the serrations 14 and splines 15 is set to 0.5 degrees or less, which improves the ignition timing control accuracy. can be secured sufficiently. In addition, the rattling noise between the serrations 14 and the splines 15 due to the above-mentioned clearance can be sufficiently absorbed by the insulator 20, and the amplitude of the load applied to the teeth of the gear 17 due to rotational fluctuations of the crankshafts 11 and 12 can be reduced, thereby improving the durability of the gear 17. In addition, the noise caused by rattling of the gear 17 can be reduced.

Furthermore, since the crankshaft 10 can be assembled to the gear 17 from both sides using the bolts 22, it is very easy to assemble the crankshaft 10 despite the structure in which the flywheel 13 and the gear 17 overlap.

In this embodiment, the torque output is generated by the gear 17 via the insulator 20 between the flywheels 13, but instead of the gear 17, an output transmission means such as a chain sprocket or a pulley may be used. Alternatively, a ring gear or the like may be disposed on the flywheel 13 so that the engine can be started by the starter motor.

Furthermore, although the output transmission means is disposed at the center of the crankshaft 10 in this embodiment, it is not limited to the center.

<Effects of the invention> As explained above, according to the invention, a flywheel is provided at the end of the divided side of the divided crankshaft, the meshing parts are engaged with each other, and
Since the structure is such that they are connected via an insulator, the length of the divided crankshafts is shortened, and each flywheel can be made lighter, which significantly reduces both the bending and torsional vibrations of the crankshaft. This has the effect of significantly reducing engine noise and, by extension, unpleasant in-vehicle noise.

[Brief explanation of the drawing]

1 to 4 are diagrams showing one embodiment of the present invention, in which FIG. 1 is a partially sectional configuration diagram, FIG. 2 is a view taken in the direction of the − arrow in FIG. 1, and FIG. in-
The sectional view, FIG. 4, is a configuration diagram when the crankshaft of FIG. 1 is assembled to an engine. 5 to 7 are diagrams showing a conventional example, in which FIG. 5 is a partially cross-sectional configuration diagram, FIG. 6 is a diagram showing a vibration state, and FIG. 7 is a diagram of vibration propagation to the vehicle body. 10... Crankshaft, 11... Front crankshaft, 12... Rear crankshaft,
13... Flywheel, 14... Serration, 15... Spline, 20... Insulator.

Claims (1)

[Scope of utility model registration request] A crankshaft for an internal combustion engine in which a crankshaft main body is divided, meshing parts that mesh with each other are formed at the ends of the divided crankshafts, and these meshing parts are meshed to connect each crankshaft. An internal combustion engine characterized in that a flywheel is provided at the end of each of the divided crankshafts on the side where the meshing portion is formed, and the flywheels are opposed to each other and the crankshafts are connected via an insulator made of an elastic body. crankshaft.