JPS6123956Y2 - - Google Patents

Description

[Detailed explanation of the invention] Industrial application field This invention is suitable for three-cylinder 120° crank arrangement or four-cylinder 120° crank arrangement.
The present invention relates to a balancer device in which primary and secondary balance weights are coaxially arranged in an internal combustion engine with a 90° cylinder crank arrangement.

BACKGROUND ART AND PROBLEMS In a reciprocating internal combustion engine, vibrations are caused by the reciprocation generated by engine operation and the inertial force of rotating moving members. Eliminating this vibration, or unbalanced force, is especially important for high-speed engines.

For this reason, reciprocating internal combustion engines are equipped with a balancer device. Regarding the balancer device related to reciprocating inertia force, there are known uniaxial balancer devices, two-axis balancer devices, four-axis balancer devices, etc. in order to balance even the primary or secondary component of the inertia force. . If these balancer devices are installed in an internal combustion engine, quiet operation without vibration can be expected, although the overall size, shape, and weight of the engine will increase.

For example, in an in-line multi-cylinder internal combustion engine equipped with a general four-axis balancer device, the secondary balancer is installed outside the primary balancer and on a different axis. However, since the secondary balancer weight directly stirs the lubricating oil in the oil bath, there is also the drawback that the horsepower loss increases.

Therefore, a balancer device that rotates the primary and secondary balance weights around the same axis has been proposed (for example, Japanese Utility Model Publication No. 54-32144, Japanese Utility Model Application Publication No. 55-321).
(Refer to Publication No. 54632), it has been attracting attention because it solves the above-mentioned disadvantages of installing a balancer device, especially the disadvantages of enlarging the engine and producing loss of horsepower.

However, the embodiments shown in such proposed publications are all four-shaft balancer devices for balancing "reciprocating inertia force", so they cannot be used with specific multi-cylinder engines, for example, with a three-cylinder 120° crankshaft. If an attempt is made to apply it as is to the engine in which the balancer device is placed, a new rolling moment will be generated and the balancer device will not be able to perform its full function.

Means for Solving the Problems Therefore, the present invention applies the advantages of the balancer device constituting the conventionally proposed coaxial balance weight to an engine with a specific crank arrangement.
The present invention aims to provide a compact internal combustion engine with even less vibration by using an intermediate mechanism between the axial balancer device and the 4-axis balancer device.

An embodiment of the present invention is shown in the accompanying drawings, where the primary and secondary combined unbalanced reciprocating inertia force is zero.
To explain an engine with a 120° cylinder crank arrangement, Fig. 1 is an overview diagram, Fig. 2 is a gear train diagram of an embodiment of the present invention, and Fig. 3 is an exploded view of the main parts seen from directions A to A in Fig. 2. Show the diagram. In these illustrations, a balance weight 2 is mounted horizontally on a crankcase 1.
A balancer drive gear 3 is wedged to one end of a crankshaft (not shown) having a crankshaft (not shown). A balancer device driven by this balancer drive gear 3 will be explained below.

That is, as shown in FIG. 1, the balancer device of this embodiment is disposed at the left and right positions (up and down in the figure) with respect to the center line X of the piston 4. The balance weight side of the side is A,
The upper side will be referred to as B, and in FIG. 3, the left side will be referred to as A, and the right side will be referred to as B.

Now, in FIG. 3, the balancer driven gear 5 of A which meshes with the balancer drive gear 3 rotates at the same speed as the balancer drive gear 3. A secondary balancer gear 6 is provided outside the balancer driven gear 5. The balancer driven gear 5 is fixed to the primary balancer weight shaft 8 with a key 7 in consideration of timing. The primary balance weight shaft 8 is supported by the crankcase 1 via a ball bearing 9, and has a cylindrical shape with some notches 10, and a balancer for an inertial couple is installed outside the cylinder. Weights 11, 11 are provided integrally. The balance weights 11, 11 are sized so that the primary reciprocating inertia couple is balanced when combined with the balance weight 2 provided on the crankshaft and having an overbalance rate of 50%.

Further, a secondary balancer weight shaft 12 coaxially inserted into the same cylinder is supported so as to be relatively rotatable via a needle bearing 9'.
is fixed with key 7.

Next, talking about the balancer weight of B, the balancer driven gear 13 of B, which meshes with the balancer driven gear 5 of A and rotates at double speed, is connected to the secondary balancer weight shaft 14 of B at the timing using the key 7. It has been fixed taking into consideration. A secondary balancer gear 6 is disposed outside the balancer driven gear 13.
The secondary balancer gear 15 of B that meshes with is fixed,
The A and B balancer weight shafts 12, 14 are rotating at the same speed.

The secondary balancer weight shaft 14 is supported by the crankcase 1 via a ball bearing 9.

Next, a calculation formula for determining the sizes of the primary and secondary balance weights will be described. Here, since the present embodiment is a three-cylinder 120° crank arrangement engine, the reciprocating inertia force is zero up to the fourth order component, so it is only necessary to consider the reciprocating inertia couple.

That is, the reciprocating inertia couple M is expressed by the following equation.

Here, R: Crank radius L: Distance between connecting rod centers λ: λ=L/R θ: Crank rotation angle ω: Crankshaft angular velocity g: Gravity acceleration W _H : Reciprocating part weight (per cylinder) α : Cylinder pitch If we take out the first-order component of the inertia couple from equation (1), we get M ₁ = _-WH /g・R・ω ²・α・√3・cos (θ+π/6) This M ₁ can be used as a balancer. Weight 2 (overbalance rate 50%) and primary balancer weight 11,11
When we balance the equal share with Here, W _B1 : Weight of primary balancer weights 11, 11 R _B1 : Position of center of gravity of W _B1 Radius S ₁ : Distance between centers of gravity of primary balancer weights 11, 11 From equation (1), the second-order component of the inertial couple When you take out the This M ₂ rotates in the secondary while the balance weight 2 rotates in the primary, so the orders are different and cannot be shared with the overbalance amount of the balance weight 2, so the secondary balance weight shaft 1
Balance the weights 2 and 14 alone.

Here, W _B2 : Weight of the secondary balancer weight R _B2 : Radius of the center of gravity position of W _B2 S ₂ : Distance between the centers of gravity of the secondary balancer weight Therefore, from equations (2) and (3), the primary and secondary Next, decide on the size of the balance weight.

Although the above explanation was about a 3-cylinder 120° crank arrangement engine, a 4-cylinder 90° crank arrangement engine also has a primary and secondary combined unbalanced reciprocating inertia force of zero, and a 3-cylinder engine with a 90° crank arrangement. Since the only difference is the phase angle from the cylinder 120° crank arrangement engine, the inertia couple generated is the same idea,
The size of the balancer weight of the balancer device installed in the engine can also be calculated in the same manner as the above calculation.

In summary, the present invention adopts the structure described in the claims for utility model registration, and therefore has the following effects.

Effects of the invention (1) The reciprocating inertia couple that occurs in an engine with a three-cylinder 120° crank arrangement or a four-cylinder 90° crank arrangement can be almost eliminated, resulting in an engine with less vibration as a whole.

(2) The primary balance weight for the primary reciprocating inertia couple has only one cylindrical shaft, and the secondary balance weight for the secondary reciprocating inertia couple has two shafts,
Since one of the shafts was inserted into the cylindrical shaft,
Not only can it be a compact balancer device that does not take up much space, but it can also eliminate secondary inertia couples, which are less than 1/3 of the size of the primary inertial couple, at twice the speed. Since the two shafts of the two rotating balance weights have small diameters,
The bearings of the two shafts can also be made smaller, reducing the weight of the balancer device and reducing the weight of the balancer.
The balancer device can be suitable for a small cylinder internal combustion engine. Furthermore, in terms of space, it consists of only one cylinder shaft and one shaft with a smaller diameter, so there is no loss of horsepower due to an oil bath, and the secondary balancer weight, which is further away from the balancer drive gear, has a cylinder shaft with a larger diameter. Since there are no holes, the overall structure can be made more compact.

(3) Multiple balancer weights with an overbalance rate of 50% are distributed evenly to the crankshafts of each cylinder in a 3- or 4-cylinder engine, and are balanced by a balancer weight installed on one cylinder shaft. The mounting of the balancer weight on the cylinder shaft can be freely distributed within the width of the crankcase without being obstructed by others, and since the balancer weight is mounted on the cylinder shaft with a large diameter, it can be lightweight.

[Brief explanation of the drawing]

FIG. 1 is an explanatory overview diagram, FIG. 2 is a gear train diagram of an embodiment of the present invention, and FIG. 3 is a developed view of the main parts as seen from the directions A to A in FIG. 2. 2: Balance weight, 4: Piston, 11:
Balance weight of A, 12: Secondary balance weight axis of A, 14: Secondary balance weight axis of B.

Claims (1)

[Scope of utility model registration request] In a balancer device for a small internal combustion engine with a 3-cylinder 120° crank arrangement or a 4-cylinder 90° crank arrangement, the primary balancer weight for the primary reciprocating inertia couple is installed evenly on the crankshaft of each cylinder. It is formed by only one cylindrical shaft that is horizontally suspended in the crankcase and is driven by the balancer drive gear, which balances the balance weight of 50%, and the secondary balance weight for the secondary reciprocating inertia couple. ,
A balancer device for an internal combustion engine, which is formed of two shafts that are twice as fast as the cylindrical shaft, and one shaft of a secondary balance weight is inserted into the cylindrical shaft so as to be relatively rotatable.