JPH0219565Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to reinforcing the crankcase of an internal combustion engine, particularly the bearing portion.

In recent years, there has been an increasing demand for internal combustion engines, especially internal combustion engines for motorcycles, to be lighter and more compact in order to improve the operating performance of the vehicle. In order to meet this demand, engine crankcases are also becoming thinner. However, as a matter of course, if the thickness is made too thin, there will be problems related to strength.

Various shafts are housed inside the crankcase, and these shafts are supported by bearings installed on the wall of the crankcase, and the force acting on the shafts is transferred to the crankcase itself through these bearings. I can accept it. In particular, reaction forces are generated between two shafts that are connected to each other by gears due to the meshing of the gears, and these reaction forces are transmitted to each bearing, so the crankcase wall between these two bearings is subject to complex stress. be placed in a state Therefore, if the crankcase is made too thin, there is a risk of cracking or buckling occurring in this area. There is also a risk that the distance between the shafts will be incorrect.
In particular, the crankshaft and balancer shaft rotate in reverse through gears and move against each other due to the action of the counterweight, so severe forces are applied to the crankcase wall between the crankshaft and balancer bearings. acts.

However, it is not advisable to increase the wall thickness of the crankcase particularly near the bearing portion where an excessive force is applied as described above, from the viewpoint of the manufacturing cost of the crankcase. There is a method of casting a connecting casting near the bearing part of the crankcase, but the casting itself is complex and heavy, and furthermore, when casting into the crankcase, a sufficient wall thickness is required for the part that encloses it. Therefore, the crankcase itself becomes thicker, larger, and heavier. Also, since large metal fittings are cast, casting becomes difficult.

Furthermore, if the crankcase is divided into upper and lower parts or front and rear parts at the bearing part, it is impossible to cast into the crankcase a cast article that surrounds the two shaft bearing parts and connects them together.

The purpose of the present invention is to provide a crankcase that supports multiple shafts and is divided along a plane along the axis of at least one shaft.The crankcase itself is made thin, and the parts where particularly large forces act are separated. By reinforcing the crankcase with reinforcing material, the entire crankcase can be made lighter and more compact.

The present invention will be explained below with reference to embodiments shown in the accompanying drawings.

The figure shows an example in which a reinforcing member according to the present invention is attached between a crank bearing and a balancer bearing.

1 indicates the entire internal combustion engine, 2 is the cylinder head, 3 is the cylinder, 4 is the piston, 5 is the intake valve,
6 is an exhaust valve, 7 is a piston pin, 8 is a connecting rod, 9 is a crankcase cover, and 10 is a crankcase.

As shown in FIG. 3, a crankshaft 11 is housed inside the crankcase 10, and a crank pin 1
2 to a connecting rod 8. 13 is a crank weight. This crankshaft 11 includes a wall portion 10' of the crankcase 10,
Ball bearing (crank bearing) 14 on 10″
It is rotatably supported by.

In this embodiment, the crankcase 10 is divided into upper and lower parts along a plane including the axis of the crankshaft 11, and the upper and lower parts are joined together by bolts 15 to form the crankcase.

Further, within the crankcase 10, a balancer shaft 16 is provided in front of the crankshaft 11 in parallel with the crankshaft 11, and via a ball bearing (balancer bearing) 17, a balancer shaft 16 is connected to the crankcase wall 10',
10". An eccentric balance weight 18 is mounted on this balancer shaft 16.
It is disposed on substantially the same vertical plane as the crank pin 12. A gear 19 is also fixed to the balancer shaft 16, and the gear 19 meshes with a gear 20 fixed to the crankshaft 11. The gear 19 and the gear 20 have the same pitch circle and the same number of teeth, so the crankshaft 11 and the balancer shaft 1
6 rotates at the same rotation speed in opposite directions.
Further, both gears 19 and 20 are engaged with each other in an angular relationship such that the balance weight 18 of the balancer shaft 16 eliminates the residual unbalanced inertia of the reciprocating mass in the engine. 27 is a flywheel of an alternator attached to the crankshaft 11.

As mentioned above, the crankshaft 11 and the balancer shaft 16
The balance weight 18 cancels the unbalanced inertial force remaining on the crankshaft 11, so a reaction force is generated between the crankshaft 11 and the balancer shaft 16, and this reaction force is applied to the bearing. Part 14,
17 to the crankcase wall,
This is counteracted by internal stresses such as compression or tension in the wall. Moreover, since this load is a repeated fluctuating load, sufficient strength is required for this wall portion, and if the wall is made too thin, there is a risk that deformation such as cracking or buckling may occur in this portion.

In addition, as shown in FIG.
If it is divided into upper and lower parts and its mating surface 21 lies approximately within a plane that includes the crankshaft 11 and/or the balancer shaft 16, this mating surface is likely to shift or open. The same applies when the crankcase is divided into front and rear parts along a vertical plane parallel to the shaft, and the mating surfaces are located near the bearing part.
When such a phenomenon occurs, the position and direction of the bearing are distorted, and the alignment between the two shafts is disturbed.

Therefore, the present invention aims to reinforce the crankcase wall in the vicinity of the bearing section, where the above-mentioned severe forces are applied.

FIG. 2 shows a reinforcing member 22 according to the present invention used in this embodiment. This reinforcing member 22
As shown in the figure, is a plate-shaped body with an appropriate thickness, and is provided with a hole 23 corresponding to the crank bearing 14 and a hole 24 corresponding to the balancer bearing 17, and bolt holes 25 at each of the four corners. It has a simple structure.

As shown in FIGS. 1 and 3, this reinforcing member 22 is attached to the inner surface of the wall portion 10' of the crankcase 10, spanning the crank bearing 14 and the balancer bearing 17. That is, the reinforcing member 22 is arranged along the inner surface of the crankcase wall 10', with the hole 23 facing the crank bearing 14 and the hole 24 facing the balancer bearing 17, and the bolt 26 passing through the bolt hole 25 facing the reinforcing member 22. crankcase wall 1
It is tightened to 0'.

A conceivable method for assembling this device is to first assemble the crankshaft 11 and balancer shaft 16 using the reinforcing member 22, then assemble this into the upper crankcase, and then assemble the lower crankcase. At this time, the reinforcing member 22 is attached to the lower crankcase by fixing a nut to the reinforcing member and inserting the bolt 26 from the outside. The reinforcing member 22 may be attached to the upper crankcase in a similar manner, but a bolt may be inserted from the inside and fastened to a screw hole provided in the crankcase.

Since the reinforcing member 22 attached in this manner shares the tension, compression, and other forces acting on the crankcase wall portion between the bearings 14 and 17, the crankcase itself can be made thin. In particular, when the mating surfaces of the crankcase, which is divided into upper and lower parts or front and rear parts, pass near these bearings as mentioned above, this mating surface must be reinforced with a single plate reinforcing member. The effect is significant.

Further, since the reinforcing member in the present invention is a single plate-shaped member with an extremely simple structure, no special space is required to attach it to the crankcase, and the entire crankcase can be made compact. Furthermore, it can be easily attached using bolts or the like, and there is no work process such as casting, so productivity can be improved.

In addition, in FIG. 3, a similar reinforcing member 22 is attached to the other crankcase wall 10'', but which bearing part the reinforcing member is attached to can be determined arbitrarily in relation to the design of the crankcase. be.

For example, in the example shown in FIG. 3, the crankshaft 11
Since the flywheel of the generator is attached to the left end of the generator, the crankshaft 11 is more likely to swing toward the left due to this inertia. Therefore, since a particularly large force acts on the wall 10', the reinforcing member 22 may be provided only on the wall 10'. That is, the walls 10', 10'' of the crankcase may have the same thickness, and only the wall 10' which requires particular strength may be reinforced.

In addition, although Figures 1 and 3 only show the main parts of a single-cylinder engine in order to simplify the drawings and make the explanation easier to understand, other types of internal combustion engines such as V-type multi-cylinder engines, etc. Needless to say, it can also be applied to institutions.

Furthermore, although the present invention has been described with respect to the crankshaft and the balancer shaft, there are many other shafts connected within the crankcase through gears, and each of these shafts is provided with a bearing. Therefore, the present invention is not limited to the crankshaft and balancer shaft, but can also be applied to reinforcement between the bearings of two or more other shafts to achieve the many effects described above. This contributes to making the crankcase lighter and more compact.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view of a crankcase cover of an internal combustion engine equipped with the crankcase of the present invention, and FIG. 2 is a perspective view of a reinforcing member.
FIG. 3 is a horizontal sectional view taken along the - line in FIG. 1. 1...Internal combustion engine, 2...Cylinder head, 3...
...Cylinder, 4...Piston, 5...Intake valve, 6
...Exhaust valve, 7...Piston pin, 8...Connecting rod, 9...Crankcase cover,
10...Crank case, 11...Crankshaft,
12...Crank pin, 13...Crank weight, 14...Ball bearing (crank bearing),
15... Bolt, 16... Balancer shaft, 17...
Ball bearing (balancer bearing), 18... Balance weight, 19, 20... Gear, 21...
Crankcase mating surface, 22... reinforcing member,
23, 24... hole, 25... bolt hole, 26...
Bolt, 27...Flywheel.

Claims (1)

[Scope of utility model registration request] In a crankcase that supports a plurality of shafts and is divided by a plane along the axis of at least one shaft, the crankcase extends along the wall of the crankcase, spanning the bearing portions of two or more shafts including the one shaft. , a crankcase for an internal combustion engine, characterized in that an integral plate-shaped reinforcing member is attached.