JPH0562259B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a weight for a V-belt type automatic transmission used in motorcycles, snowmobiles, etc.

[Conventional technology]

A V-belt type automatic transmission has a V-belt stretched between a driving pulley and a driven pulley, and each of the driving pulley and driven pulley is a fixed pulley fixed to a rotating shaft. It has a plate and a movable pulley plate which forms a belt groove opposite to the fixed pulley plate and is movable back and forth in the axial direction. Then, by pushing the movable pulley plate of the driving pulley by the centrifugal force of a weight that engages with the back surface and peripheral wall of the movable pulley plate and rotates with the driving pulley, the V-belt and the pulley are connected. It is configured to continuously change the engagement radius.

In particular, this V-belt type automatic transmission has been widely used in scooters, family bikes, utility bikes, snowmobiles, etc. in recent years because it provides a smooth gear ratio without steps and has a simple structure. It is used.

By the way, the weight of this type of transmission constantly pushes the movable pulley plate to change the engagement radius with the V-belt in response to fluctuations in the rotational speed of the rotating shaft. It is necessary to move the movable pulley plate smoothly and not wear out the movable pulley plate. For this reason, conventional weights have generally been made of resin into a cylindrical shape, and are manufactured by injecting resin through a single edge gate provided on the outer peripheral surface of the weight.

[Problem that the invention seeks to solve]

However, such a manufacturing method has a problem in that the roundness of the weight cannot be obtained when molded from fiber-reinforced resin. This is because the orientation of the fibers filled in the resin is different from other parts in the weld part where the two tips of the resin flowing in different directions in the cavity collide, and the molding shrinkage rate in this weld part is different from that in other parts. This is thought to be due to the difference. As a result, the weld part protrudes,
Smooth rolling cannot be achieved, which causes uneven wear.

[Means for solving problems]

The present invention was made in view of the above circumstances, and provides a method for manufacturing a V-belt type automatic transmission weight, which allows weights with good roundness to be manufactured from fiber-reinforced resin. The method for manufacturing a weight according to the present invention involves resin molding a weight for a V-belt type automatic transmission, which is formed by covering the outer circumference of a cylindrical weight adjusting member with a resin part, and forming a cylindrical cavity and a shaft in this cavity. This is carried out by injecting fiber-reinforced resin from the center of the gate into a mold in which a gate consisting of a disc-shaped space communicating all around the inner circumference of one end is formed.

[Effect]

In the present invention, by injecting the fiber-reinforced resin from the periphery in the axial direction, the influence of the orientation of the filled fibers on the molding shrinkage rate is reduced.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a mold used in the method for manufacturing weights according to the present invention, FIG. 2 is a cross-sectional view taken along the line -- in FIG. 1, and FIG. These are cross-sectional views showing essential parts of the V-belt type automatic transmission provided, and in these figures, the reference numeral 1 indicates a unit swing type engine such as a scooter. This engine 1 includes an engine main body 2 disposed at the front, a rear wheel shaft (not shown) disposed at the rear and connected to a rear wheel pulley shaft via a reduction gear, and the power of the engine main body 2 is transferred to a crankshaft 3. A V-belt type automatic transmission 4 that transmits power to the rear wheel pulley shaft via a centrifugal clutch is held together by a transmission case 5, and functions as a component of a suspension system that suspends the rear wheels.

The V-belt type automatic transmission 4 has a crankshaft 3
It consists of a crank-side pulley 6 supported on the rear-wheel-side pulley 6, a rear-wheel-side pulley rotatably supported on the rear-wheel-side pulley shaft via a collar, and a V-belt 7 stretched between these pulleys. .

The crank-side pulley 6 has a fixed pulley plate 6a fixed to the crankshaft 3, and a movable pulley plate 6b that forms a belt groove opposite to the fixed pulley plate a and is movable back and forth in the axial direction. .

Reference numeral 8 denotes a weight, which is formed into a cylindrical shape as shown in an enlarged longitudinal section in FIG. 4, and has a cylindrical weight adjustment member 9 made of a metal material such as iron or brass inside. 10 is the movable pulley plate 6
This is a cam member fixed on the crankshaft 3 and located on the back side of the crankshaft 3. The weight 8 is interposed between the movable pulley plate 6b and the cam member 10, and is held between the cam surfaces of both parts so as to be able to slide and roll in the radial direction. The cam surface is oriented in the outer radial direction and the opposing interval gradually increases so that the centrifugal force of the weight 8 accompanying the rotation of the crank pulley 6 pushes the movable pulley plate 6b and engages with the V-belt 7, changing the radius. It is formed to be narrow.

11 is a movable pulley plate 6b and a cam member 10
This is a guide member that is interposed between the cam member 10 and the movable pulley plate 6b.
The dashed line in FIG. 3 shows the state of the V-belt type automatic transmission 4 when it is in the top position.

When manufacturing the weight 8 of the V-belt type automatic transmission described above, first the mold 12 and the weight adjustment member 9 are processed, and after the weight adjustment member 9 is held inside the cavity 13 formed in the mold 12. , a fiber reinforced resin is injected into the cavity 13.

To explain this manufacturing method in detail, first, the lower mold 12a and the upper mold 12b are processed to form a cylindrical cavity 13 between these members, and a metal material is processed to form the weight adjustment member 9 into a cylindrical shape. form into a shape. Then, the weight adjustment member 9 is inserted into the protrusion 14 of the lower mold 12a, and the cavity 1 is closed.
Hold inside 3. Here, the weight adjustment member 9 is formed to have a shorter length in the axial direction than the cavity 13, and is held in a state in which the outer surface is surrounded by the cavity 13 by the stepped portion 15.

Next, the molten fiber-reinforced resin is injected into the cavity 13 from the runner 17 at the center of the gate 16, and the weight 8 is formed in the cavity 13 by cooling and solidifying the resin.
The gate 16 connects the upper mold 12b to the protrusion 14.
It is formed as a disc-shaped space by being slightly spaced apart from the upper end surface of the gate 16, and communicates with a runner 17 at the center of the gate 16. That is, the weight 8 is formed in a cylindrical shape, and the gate 16 is provided so as to extend in the circumferential direction at a portion forming an inner peripheral edge 8a of one open end of the weight 8.

The base materials of the fiber-reinforced resin to be injected include nylon resin, polyacetal resin (POM), polytetrafluoroethylene resin (PTFE), polybutylene terephthalate resin (PBT), polypropylene resin (PP), polyethylene resin (PE), Alternatively, it is said to be phenolic resin, polyimide resin, etc.
The fibers to be filled may be glass fibers, carbon fibers, or aramid fibers (for example, Kevlar fibers manufactured by DuPont). Further, a solid lubricant such as polytetrafluoroethylene resin (PTFE), graphite, molybdenum disulfide (MoS ₂ ) may be mixed into the fiber-reinforced resin. However, the above
PTFE is not used if the base material is PTFE.

In the method for manufacturing a weight for a V-belt automatic transmission configured as described above, when molten fiber-reinforced resin is injected from the runner 17, the runner 17 is located at the center of the disc-shaped gate 16. Therefore, the resin is dispersed so that the flow rate is approximately equal in all directions. The dispersed resin flows into the cavity 13 from the inner peripheral edge 8a of one open end of the weight 8 through the gate 16, flows in the axial direction, and is filled into the cavity 13. Thereafter, when the resin is cooled and solidified, the resin is formed into a shape corresponding to the cavity 13, so that the weight 8 can be manufactured.

Therefore, when injecting the resin, it is possible to keep the flow direction constant and prevent the weld portion from occurring as in the conventional case. Therefore, the molding shrinkage rate of the entire weight 8 can be made substantially equal, and the influence of the orientation of the filled fibers on the molding shrinkage rate can be reduced. This is thought to be because by keeping the flow direction of the resin constant, the orientation of the filled fibers becomes equal.

In the above embodiment, an example was described in which the weight adjusting member 9 was insert-molded when the weight 8 was molded, but it can also be fixed by press-fitting or the like after molding.

〔Effect of the invention〕

As explained above, according to the present invention, the V
A resin molded weight for a belt-type automatic transmission is made of a metal molded material having a cylindrical cavity and a gate consisting of a disc-shaped space that communicates with the inner circumferential side of one end in the axial direction of the cavity over the entire circumference. Since the fiber-reinforced resin is injected into the mold from the center of the gate, the flow direction of the fiber-reinforced resin can be set to a constant axial direction, and molding shrinkage can be made substantially equal throughout.

Therefore, since the influence of the filled fibers on the molding shrinkage rate can be reduced, weights with good roundness can be manufactured from fiber-reinforced resin.
As a result, it is possible to smoothly roll the weights and reduce uneven wear, so it is expected that the lifespan will be extended.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a mold used in the method for manufacturing weights according to the present invention, FIG. 2 is a cross-sectional view taken along the line -- in FIG. 1, and FIG. FIG. 4 is a cross-sectional view showing essential parts of the V-belt type automatic transmission provided, and FIG. 4 is a vertical cross-sectional view showing an enlarged weight. 4... V-belt type automatic transmission, 6a... Fixed pulley plate, 6b... Movable pulley plate, 8
... Weight, 8a ... Inner peripheral edge, 9 ... Weight adjustment member, 10 ... Cam member, 12a ... Lower mold,
12b... Upper mold, 13... Cavity, 16
……Gate.

Claims (1)

[Scope of Claims] 1. A cylindrical weight adjusting member which is interposed between a movable pulley plate forming a belt groove opposite to a fixed pulley plate and a cam member, and is formed by covering the outer periphery of a cylindrical weight adjusting member with a resin part. A method for manufacturing a weight for a V-belt automatic transmission includes a cylindrical cavity, located on the axial center side of the cylindrical cavity, and having an outer circumference extending all the way around the inner circumference of one axial end of the cavity. The V-belt type automatic transmission is characterized in that the resin part is formed by injecting fiber-reinforced resin from the center of the gate into a mold in which a gate consisting of a disc-shaped space communicated with each other is formed. Method of manufacturing machine weights. 2. In the method for manufacturing a weight for a V-belt automatic transmission as set forth in claim 1, the cylindrical weight adjustment member is held inside the cavity in advance, and then the fiber reinforced resin is injected. A method for producing weights for V-belt automatic transmissions. 3. The method for manufacturing a weight for a V-belt automatic transmission as set forth in claim 1, characterized in that after the resin part is molded, a cylindrical weight adjustment member is fixed to the resin part by press-fitting. A method for manufacturing weights for V-belt automatic transmissions.