JPH0519632Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Purpose of the Invention] (Field of Industrial Application) This invention relates to a balancer for a unit swing engine of a two-wheeled motor vehicle, which is installed to reduce vibration.

(Prior art) In order to reduce vibrations caused by the vertical movement of the piston and the rotation of the crank as much as possible,
Some models are equipped with a single-axis balancer. A single-shaft balancer suppresses the above vibration by rotating a balancer weight that is mounted parallel to the crankshaft at the same speed in the opposite direction to the crankshaft, but it must be as close to the crankshaft as possible. is desirable, and 4
In a cycle engine, it is placed inside the crankcase. Further, in order to prevent the occurrence of a couple, the center of gravity of the weight and the centers of gravity of the piston and crank to be balanced are set to rotate on the same plane perpendicular to the axis.

A typical structure that satisfies these conditions is
As shown in the figure. A balancer shaft b is pivotally supported within a crankcase a in close proximity to the outer periphery of a crank wheel c, and a balancer weight d is rotated between two crank wheels c.

The size of this balancer weight d is determined by the synergistic effect of mass and radius, and in this case, the diameter is relatively large. Therefore, the crankcase a, which allows the balance weight d to rotate, becomes larger accordingly.

When this single-axis balancer is installed in a unit swing engine often used in motorcycles, the distance La from the crankshaft to the integrally supported rear wheel e becomes longer, and the unit case becomes longer. There is a problem with this. Therefore, as shown in Figure 3, two balance weights fa,
By using fb, a method is adopted in which the diameter is made smaller to make the crankcase a smaller and the distance Lb to the rear wheel e is reduced. In this case, balance weights fa and fb are placed outside the crankcase a.

However, in such a configuration, the balancer axis b
It is necessary to manufacture the and balance weights fa and fb separately and assemble them via the spline g and key h. Furthermore, in this type of engine, a cam drive sprocket gear j for driving a timing cam is formed on one crankshaft (left side in the figure) ia, and a cooling fan is pivotally supported on the other crankshaft ib. In other words, the timing chain chamber A is installed on one side of the crankcase a, and the cooling fan chamber B is installed on the other side, and although there is no problem with the timing chain chamber A side, the cooling fan chamber B is of a dry type. , it is necessary to cover the balance weight fb with a special cover k.
Alternatively, use an oil seal to isolate it from the crankcase a. For this reason, along with the three-part structure of the balancer, there is a problem of increased cost.

(Problem to be solved by the invention) As mentioned above, in a unit swing engine in which the timing chain chamber is connected to one side of the crankcase and the cooling fan chamber is connected to the other side, the single-shaft balancer has a two-weight structure. 3.
In view of the fact that it is separated and requires a dedicated cover and oil seal, there are major problems in terms of productivity and cost.This idea was designed to solve this problem by reducing the number of parts and using a dedicated cover. It is an object of the present invention to enable a two-weight type single-axis balancer to be installed without using a unit swing engine, and to make a unit swing engine more compact.

[Structure of the idea]

(Means for Solving the Problems) In order to achieve the above object, the unit swing engine balancer of this invention has a timing chain chamber on one side of the crankcase and a cooling fan chamber on the other side. In a unit swing 4-cycle engine in which a crankshaft is pivotally supported in a crankcase, the crankshaft is equipped with a cam drive sprocket gear at a position corresponding to the timing chain chamber, and a cam drive sprocket gear is installed in the crankcase on the side of the cooling fan chamber. A starter driven gear and a one-way clutch are arranged in parallel at corresponding positions, and a clutch outer of the one-way clutch is fixed to the side of the crank wheel.
The clutch inner is constituted by the boss portion of the starter driven gear extending toward the crank wheel, and a balancer shaft is provided horizontally in the crankcase.
One end of the balancer weight protrudes into the timing chain chamber and is interlocked with the crankshaft at the same speed in the opposite direction by a gear, and one of the balancer weights distributed at both ends of the balancer shaft is connected to the cam sprocket gear in the timing chain chamber. The one-way clutch is located opposite the one-way clutch, and the other is located within the crank chamber facing the one-way clutch.

(Function) With the above configuration, the balancer shaft does not protrude toward the cooling fan chamber, so there is no need for an oil seal or cover, and at the same time, the balancer weight on the cooling fan chamber side has a two-part structure that is integrated with the balancer shaft. Easy to manufacture and assemble, high productivity,
Costs are improved. Furthermore, the cam drive sprocket gear and one-way clutch installed on the crankshaft have a smaller diameter than the crank wheel, and the two balancer weights installed on the bansha shaft face the cam drive sprocket and one-way clutch, respectively. Since it is installed, the distance between the crankshaft and balancer shaft can be shortened. For this reason, along with the adoption of the 2-weight method,
The unit swing engine can be made more compact and lighter.

(Embodiment) FIG. 1 is a sectional view of a unit swing engine crankcase showing an embodiment of this invention.

A crank wheel 3 connected to a connecting rod 2 is housed within the crank case 1. The left and right crankshafts 4a and 4b, which support the crank wheel 3 using crank bearings 14a and 14b, protrude outward from the crankcase 1, and one crankshaft 4a (on the left side in the figure) has a cam drive for driving a timing cam. A sprocket gear 5 is formed. A cooling fan is pivotally supported on the other crankshaft 4b. Therefore, a timing chain chamber A is connected to one side of the crankcase 1 in a wet type, and a cooling fan chamber B is connected to the other side in a dry type. crank case 1
Of course, the interior is wet. Note that 6 indicates a starter driven gear that is mounted on the crankshaft 4b via a one-way clutch 7 in the crankcase 1.

The starter driven gear 6 and the one-way clutch 7 are arranged in parallel on the crankshaft 4b as shown in FIG. The one-way clutch 7 is provided with a clutch outer 7a and a clutch inner 7b facing each other in the radial direction, the clutch outer 7a being fixed to the side of the crank wheel 3, and the clutch inner 7b being a boss portion of the starter driven gear 6 extending toward the crank wheel 3. The boss portion (clutch inner 7b) of the starter driven gear 6 is rotatably supported by the crankshaft 4b.

By arranging the starter driven gear 6 and the one-way clutch 7 in parallel, the starter driven gear 6 can be made smaller.

Next, inside the crankcase 1, there is a crankshaft 4.
A balancer shaft 8, which is parallel to a and 4b and close to the outer periphery of the crank wheel 3, is mounted astride both side walls of the case. One end thereof protrudes into the timing chain chamber A, and the balance weight 9a is fixed thereto. A balancer weight 9 is attached to the other end of the balancer shaft 8.
b is integrally formed. Both balancer weights 9a and 9b are set in mass and diameter so as to be distributed in a well-balanced manner, and a groove 10 is provided in the balancer weight 9b so as not to collide with the starter driven gear 6. balance weight 9
A is disposed to face the cam drive sprocket gear 5, and one of the balance weights 9b (left side in FIG. 1) is disposed to face the one-way clutch 7. A balancer drive gear 11 is fixed to the crankshaft 4a and meshes with a balancer driven gear 12 on the balancer shaft 8, so that the balancer shaft 8 is rotated in the opposite direction and at the same speed as the crankshafts 4a and 4b.

With the above configuration, the end of the balancer shaft 8 on the side of the cooling fan chamber B is pivotally supported within the crankcase 1, so that it is completely isolated from the dry cooling fan chamber B. Therefore, there is no need to use a dedicated cover or oil seal on the cooling fan chamber B side of the crankcase 1, so the number of parts can be reduced, ease of assembly can be improved, and costs can be reduced. In addition, since the balancer shaft 8 can be assembled into the crankcase 1 with the balancer weight 9b present, the balancer weight 9b can be integrally formed with the balancer shaft 8, and the balancer shaft 8 can be provided integrally with the balancer shaft 8.
A weight method can be adopted. Moreover, the balancer weight 9a is arranged opposite to the small diameter cam drive sprocket gear 5, and one of the balancer weights 9b is arranged opposite to the small diameter one-way clutch 7. With these, the diameters of both balancer weights 9a, 9b can be made smaller, and the distance L between the rear wheel 13 and the crankshafts 4a, 4b can be made smaller.
The length of the unit case that pivotally supports the rear wheel 13 at the rear can be shortened, and a compact unit swing engine can be designed by being equipped with a single-shaft balancer.

[Effect of idea]

As described above, the balancer for a unit swing engine according to this invention has a crankcase with a wet timing chain chamber on one side and a dry cooling fan chamber on the other side, and the balancer weight on the cooling fan chamber side. is located in the crankcase facing the one-way clutch installed on the crankshaft, and the other balancer weight is located in the timing chain room facing the cam drive sprocket gear installed on the crankshaft. Equipped with a single-axis balancer of the same type, there is no need to use a special cover or oil seal on the cooling fan chamber side of the crankcase, and the balancer can be assembled in two parts, making production and assembly easier. Costs are reduced, the starter driven gear and one-way clutch are arranged in parallel on the crankshaft, and the clutch inner of the one-way clutch is formed from the boss of the starter driven gear, making it possible to reduce the outer diameter of the starter driven gear. Moreover, the distance between the crankshaft and the balancer shaft is shortened, which has the effect of making the unit swing engine more compact.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a unit swing engine crankcase showing an embodiment of this invention;
FIG. 3 is a sectional view of a unit swing engine crankcase, each illustrating a conventional balancer. 1... Crank case, 3... Crank wheel, 4a, 4b... Crank shaft, 5... Cam drive sprocket gear, 6... Starter driven gear, 8... Balancer shaft, 9a, 9b... Balance weight.

Claims (1)

[Scope of utility model registration request] In a unit swing 4-cycle engine in which a timing chain chamber is installed on one side of the crankcase and a cooling fan chamber is installed on the other side, and a crankshaft is pivotally supported on the crankcase, the crankshaft corresponds to the timing chain chamber. At the same time, a starter driven gear and a one-way clutch are arranged in parallel at the corresponding positions in the crankcase on the side of the cooling fan chamber, and the clutch outer of the one-way clutch is placed on the side of the crank wheel. The clutch inner is configured with the boss of the starter driven gear extending toward the crank wheel, and a balancer shaft is provided horizontally within the crankcase, one end of which protrudes into the timing chain chamber and is connected to the gear. One of the balancer weights distributed at both ends of the balancer shaft is interlocked with the crankshaft in the opposite direction at the same speed, and one of the balancer weights is positioned opposite the cam sprocket gear in the timing chain chamber, and the other is positioned in the crank chamber opposite the cam sprocket gear. A unit swing engine balancer characterized by being positioned opposite the one-way clutch.