JPS6323625Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an in-line five-cylinder engine, and particularly to a structure for arranging balance weights to reduce the load on main bearings.

In a reciprocating internal combustion engine, engine vibration, especially In order to prevent low frequency vibrations, various ideas have been made regarding balance weights (such as Japanese Utility Model Application No. 55-165141).

In the case of a conventional in-line five-cylinder engine, the inertia force is well balanced, but the inertia couple is first-order (however, a phenomenon that occurs n times per crankshaft rotation is defined as n-order),
There is a problem in that the secondary inertia couple remains unbalanced, and this remaining inertia couple causes low-frequency vibrations with large amplitudes, causing discomfort to the occupants.

On the other hand, I mentioned earlier that the inertial force has reached a good balance, but this is the result of inertial forces being exerted on each other by moving parts separated from each other, and the engine as a whole is balanced. If you look at the parts, there is a large inertial force at work. As a result, the load on the main bearings, particularly in the center of the engine, becomes excessive, which may lead to a decrease in its durability.

This idea was made in view of the above circumstances.
By appropriately setting the number, mounting position, and mounting angle of balance weights, the purpose is to reduce not only the inertia couple but also the load on the main bearing.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 shows the crankshaft of the in-line five-cylinder engine of this embodiment.

In Figure 1, 1 is a cylinder block (not shown)
The crankshaft is supported through bearings on the crankshaft, and first to fifth crank pins 2 to 6 are sequentially provided from the front end side to connect to the pistons of each cylinder through connecting rods. Four first to fourth balance weights 7 to 10 are attached to each of the first, fifth, sixth, and tenth webs. 11 is a flywheel. These first to fourth balance weights 7 to
As shown in FIG. 2, when viewed clockwise from the front end of the crankshaft 1, the mounting position of the first balance weight 7 is relative to the first crank pin 2.
180°, second balance weight 8 is 0°, third balance weight 9 is 288°, fourth balance weight 10
are mounted at positions 108° out of phase with each other. This mounting position is optimal for reducing the load on the main bearing at the center of the crankshaft 1, and can also reduce the effects of the residual inertia couple, as determined by the analysis results described below. .

When the ignition order is #1-#2-#4-#5-#3, the first-order inertia couple M ₁ in the cylinder reciprocating section
It has been confirmed that the following remains.

However, in the present invention, the size of this reciprocating part is The fluctuating remaining inertial couple is half-balanced (converted to a rotating couple with a size of 1/2 |M ₁ |) using a balance weight, so that the remaining inertial couple becomes a rotating couple.

Therefore, the inertia couple Mc′ required for the balance weight when half-balancing is becomes.

Therefore, the final inertial couple Mc required for the balance weight is obtained by adding the element of the rotational motion part weight Wrev to the above equation (2). becomes.

There are various arrangements of balance weights that satisfy the inertia couple Mc of equation (3), but in particular, the balance weight should be placed between the third crank pin 4 at the center of the crankshaft 1 to maximize the bearing performance of the main bearings on both sides. , balance weights are provided in the fifth web and the sixth web, and these balance weights 8 and 9 are arranged in a direction that balances the resultant force of the inertial forces of the cylinders on both sides of the main bearing, that is, in the above-mentioned angular position of the first crank. The position is 0° and 288° out of phase with respect to pin 2. At this time, the first balance weight 7 and the fourth balance weight 10 are
The positions are 180° and 108° out of phase. Even if the balance weight is placed at a different angular position, it is possible to satisfy the inertia couple Mc (shown in Figure 3) in equation (3), and it is possible to reduce the inertia couple and improve engine balancing. Although it can be maintained in good condition, it becomes impossible to cancel out the inertial force in each moving part, and it becomes impossible to improve the bearing performance of all main bearings, which is another feature.

Further, the amount of static unbalance of the balance weight must satisfy the above-mentioned inertia couple Mc required for the balance weight. Note that the amount of static unbalance is expressed as f=W·r, where W is the weight of the balance weight, and r is the distance between the center of gravity of the balance weight and the center of the crankshaft.

Here, let the amount of static unbalance with each balance weight be f ₁ , f ₂ , f ₃ , f ₄ and let the inertia couple M ₂ , M ₃ on both sides with respect to the center of the third cylinder be M ₂ .
= f ₁・ l ₂ − f ₂・ l ₁ , M ₃ = f ₄・ l ₂ − f ₃・ l ₁ , which are the directions shown in Figure 3, and for these to satisfy Mc, M ₂ = In the case of M ₃ , in this case f ₁ = f ₄ , f ₂ = f ₃
It is.

Therefore, from Fig. 3, f ₁ · l ₂ − f ₂ · l ₁ = 1/2 sin36° | Mc |.

Then, f ₂ is determined from the balance condition of the inertia force in the third cylinder, and normally the crankshaft
Since l ₂ ≒ (8~9) l ₁ , from these conditions,
Taking into account the margin of balance weight, which takes into account the workability of crankshaft balancing processing, f ₁ and
The ratio of f ₂ is calculated as follows: f ₁ :f ₂ =1:(1 to 1.3).

Therefore, by setting the static unbalance amount ratio of the balance weight of the crankshaft as f ₁ : f ₂ : f ₃ : f ₄ = 1: (1 to 1.3): (1 to 1.3): 1, it is possible to improve the balance processing. Work efficiency is improved and the load on the crankshaft can be reduced.

As explained above, according to the present invention, the balance weight is mounted in a position where the inertia couple can be reduced and the load on the main bearing can be reduced in the inline five-cylinder engine, so engine vibration can be suppressed. By reducing the weight of the crankshaft, the weight of the engine itself can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a simplified perspective view showing one embodiment of the present invention;
FIG. 2 is a diagram illustrating the arrangement of the balance weights when viewed from the front end of the crankshaft of the same embodiment, and FIG. 3 is a diagram illustrating the relationship of the inertial couple. 1...Crankshaft, 2~6...Crank pin, 7~
10...Balance weight.

Claims (1)

[Scope of utility model registration request] A balance weight is attached to each of the first, fifth, sixth, and tenth webs from the front end of the crankshaft, and when viewed clockwise from the front end of the crankshaft, the first, fifth, and An in-line five-cylinder engine characterized in that the balance weights of the sixth and tenth webs are mounted at positions 180°, 0°, 288°, and 108° out of phase with respect to the first crank pin, respectively. .