Land vehicles: wheels and axles – Wheel – Balancing device
Reexamination Certificate
1999-07-16
2001-06-26
Morano, S. Joseph (Department: 3617)
Land vehicles: wheels and axles
Wheel
Balancing device
Reexamination Certificate
active
06250721
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a wheel balance weight.
2. Description of Related Art
In an automobile wheel assembly including a wheel and a tire, a dynamic imbalance may exist when the wheel is rotated. Generally, to compensate for this imbalance the wheel is provided with a balance weight.
As illustrated in
FIGS. 14-16
, a conventional balance weight
1
includes a weight body
2
made from lead (Pb) and a clip
3
having an end which is embedded in said weight body. The technical specification of the conventional balance weight is determined by Japanese Automobile Standards Organization (JASO). The manufacturing method and the specification thereof are as follows:
Weight Body: The weight body may be made of lead (Pb). The weight body is manufactured by casting.
Clip: Clip is a hook for mounting the balance weight to a flange of a wheel. The clip may be made of spring steel. The clip is fixed to the weight body by embedding an end portion of the clip in the weight body when the weight body is cast.
Surface Treatment: Surface treatment for prevention of rust and galvanic corrosion is applied to the clip.
Heat Treatment: To obtain an elastic characteristic, a specific heat treatment is applied to the clip before the end of the clip is cast in the weight body. Because the melting point of Pb is low, the elastic characteristic of the clip obtained by the heat treatment is not degraded when the end of the clip is cast in the weight body.
Recently, there has been a trend to avoid the industrial use of heavy metals such as Pb for the purpose of environmental protection. Thus, the Pb of the balance weight is apt to be substituted for other materials.
As an alternative, from an industrial viewpoint, materials such as Fe or Cu can be used. Those materials are inexpensive, environmentally friendly and have a relatively high density.
However, since those materials have a relatively high melting point, the following problems occur with respect to manufacture of the weight body and to coupling of the clip to the weight body:
First, in a case where an end of the clip is cast in the weight body, since the melting points of the clip and the weight body are close to each other, the elastic characteristic of the clip is degraded or deteriorated, and the effect of the casting is weakened. If heat treatment of the clip is conducted after the clip is cast with the weight body, the condition of the heat treatment is severe because heat to the clip will be absorbed by the weight body, and, as a result, the heat treatment will be accompanied by an increase in cost.
Second, in a case where a surface treatment is applied to the clip before the clip is cast with the weight body, the clip is exposed to a high temperature during casing, and the heat-treated surface is degraded. Therefore, various limitations or modifications of the manufacturing will be necessary.
In order to solve these problems, the inventors have investigated manufacturing the weight body by cold forging and coupling the clip to the weight body by caulking.
However, there are the following problems with manufacturing the weight body by cold forging:
First, cold-forging the material to the configuration of the weight body requires a large pressing force and a large-sized press machine which increases the manufacturing cost.
Second, it is difficult to form the material into the configuration of the weight body in one pressing step; a plurality of pressing steps will be necessary. This results in a need for a plurality of sets of pressing dies which also increases the manufacturing cost.
For the above-described reasons, the cost of the balance weight will be high. Solutions for the cost problem are thus desired.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a wheel balance weight which is preferable from the viewpoint of environmental protection.
Another object of the present invention is to provide a wheel balance weight having a weigh body which is easy to form.
Another object of the present invention is to provide a wheel balance weight having a clip whose spring characteristic and surface treatment layer are not deteriorated during coupling of the clip to the weight body.
The above-described objects are performed by a wheel balance weight according to the present invention.
The wheel balance weight according to the present invention includes a weight body and a clip fixed to the weight body.
The weight body is preferably made from ductile cast iron. The weight body includes a longitudinal portion extending in an arc along a flange of a wheel to which the wheel balance weight is to be coupled, a radial portion extending in a radial direction of the arc, and a configuration including a contact surface at which the wheel balance weight contacts the flange of the wheel. The weight body includes a groove at the contact surface at a longitudinally central portion of the weight body. The groove includes a bottom surface receding from the contact surface and a pair of side surfaces extending from the bottom surface to the contact surface at width ends of the bottom surface. The groove includes a radially extending portion which extends in the radical direction of the arc and has a depth equal to or greater than a thickness of the clip. The weight body and the groove are formed by casting.
The clip is provided with elasticity. The clip extends along the bottom surface of the groove of the weight body. The clip is folded at an end of the flange of the wheel so as to hold the flange of the wheel, and clip includes an engaging portion for engagement with the weight body.
The clip is fixed to the weight body by disposing the clip in the groove of the weight body and caulking at least a portion of the pair of side surfaces of the radially extending portion of the groove thereby fixing width end portions of the clip.
The weight body may have an engaging portion at the pair of side surfaces of the radially extending portion of the groove. The weight body engages with the clip at the engaging portion of the weight body in an at least radially inwardly direction of the arc.
The engaging portion of the weight body may include projections projecting from each of the pair of side surfaces toward an opposed side surface.
The weight body may include a pillar at the botton surface of the radially portion of the groove. The pillar extends in a direction away from the bottom surface. The pillar has a head portion. The clip has an aperture for letting the head portion of the pillar pass therethrough. The head portion of the pillar is caulked after the head portion of the pillar is caused to pass through the aperture of the clip when the clip is coupled to the weight body.
The engaging portion of the weight body may include tapered portions formed at the pair of side surfaces of the groove. The tapered portions of the engaging portion of the weight body are tapered such that a distance between the pair of side surfaces of the groove is decreased in a direction extending radially outward in the radial direction of the arc.
The clip may have opposite side surfaces which are tapered such that a distance between the opposite side surfaces is decreased in a direction away from the bottom surface of the groove.
The above-described wheel balance weight is preferable from the standpoint of environmental protection because lead (Ph) is not used. Further, because the weight body is formed by casting, forming is easy as compared with forming by cold forging. Furthermore, because the clip is coupled to the weight body not by casting but by caulking, the spring characteristic and the surface treatment of the clip are not deteriorated by heat.
REFERENCES:
patent: D. 119321 (1940-03-01), Mills
patent: D. 132030 (1942-04-01), Kalajian
patent: D. 161006 (1950-11-01), Dailey
patent: 2122065 (1938-06-01), Hume
patent: 2197364 (1940-04-01), Hatch
patent: 2218410 (1940-10-01), Weaver
patent: 2248265 (1941-07-01), Wright
patent: 2258011 (1941-10-01), Inman
patent: 2469997 (1949-05-01), Simpson
pa
Maruyama Saburo
Oba Kentaro
Morano S. Joseph
Nguyen Long Bao
Pillsbury & Winthrop LLP
Topy Kogyo Kabushiki Kaisha
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