Internal-combustion engines – Cooling – Air-cooled
Reexamination Certificate
1999-05-13
2001-01-30
Dolinar, Andrew M. (Department: 3747)
Internal-combustion engines
Cooling
Air-cooled
C123S185300, C416S060000
Reexamination Certificate
active
06178931
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a hub of a plastic fan wheel for an internal combustion engine. The fan wheel moves a flow of cooling air to the engine. A hub sleeve of the hub is made of a material having a high tensile strength and is especially of metal and carries a wheel body made of plastic. The hub sleeve is fixedly mounted on the crankshaft of the engine to rotate therewith and is axially fixed with a clamping element. The fixed connection of the hub sleeve to the crankshaft can be additionally secured by a form-tight connecting element in the form of an entraining element such as a key or the like.
BACKGROUND OF THE INVENTION
Known hubs for plastic fan wheels are assembled of several parts. In the conventional arrangement, the hub sleeve is a turned part having a periphery onto which a disc is pressed and attached. The plastic fan body is injection molded on this piece. The disc is soldered to the periphery of the steel hub sleeve and engages into the plastic wheel body on the fan wheel so that the torque transmission between the hub sleeve and the wheel body is ensured.
A starter ring is attached concentrically to the hub axis at the end face of the hub. The starter ring can be entrained by a starter device of the engine which can be coupled thereto. The starter device can, for example, be a pull-rope starter having a starter rope. When the starter rope is pulled, entraining elements are brought into meshing engagement with the teeth of the starter ring. When pulling the starter rope, a torque is generated and transmitted from the starter ring via the plastic of the wheel body and the hub sleeve to the crankshaft thereby bringing the engine into operation.
The manufacturing costs of such a hub are very high because, in addition to the material costs of the individual hub components, the manipulative operations when positioning and assembling the hub components are very time intensive when done with the required care.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a hub of a fan wheel for an internal combustion engine which is cost effective to manufacture.
The invention is a hub unit of a fan wheel for an internal combustion engine having a crankshaft and a starter device. The hub unit includes: a wheel body made of plastic; a hub sleeve defining an axis and being made of a high tensile strength material and carrying the wheel body; means for holding the hub sleeve on the crankshaft so as to prevent rotation relative thereto; a clamping element for axially fixing the hub sleeve on the crankshaft; a starter ring concentric with the axis and adapted for a clutch engagement with the starter device so as to be entrainable thereby; and, the starter ring and the hub sleeve being originally formed as a single piece to define a hub housing.
The hub sleeve and the starter ring are configured in a formed hub housing as one piece. The hub housing can be cast. The individual elements of this housing and especially the hub sleeve and the starter ring are arranged relative to each other in the same position for each cast component. Even for a large number of hubs, components are manufactured by casting which all have the same form which can be easily provided with the plastic wheel body. Furthermore, with the one-piece configuration of the hub housing, the torques, which act on the starter ring during actuation of the starter device, are transmitted directly via the metal base body of the hub housing to the crankshaft. No stresses occur in the plastic material. The hub housing is preferably made of aluminum and is manufactured in accordance with a diecasting method.
Radially aligned anchors are preferably formed on the periphery of the hub housing. The anchors project beyond the starter ring in the radial direction and grip into the plastic wheel body in the fan wheel. The torque transmission between the hub and the fan wheel body takes place via the anchors. A gap or a space remains between the anchors and this space is filled with the plastic material of the wheel body. In this way, the form-tight connection between the aluminum hub and the plastic wheel body is improved.
The anchors are advantageously mounted so as to be rotationally symmetrical on the hub housing. The number of the anchors can be equal to the number of the entraining teeth at the inner side of the starter ring so that each entraining tooth is assigned to an anchor. The anchors grab advantageously on the hub sleeve so that the anchors are connected to the crankshaft and directly transfer torque thereto. The anchors are advantageously configured so as to be flat and lie in a plane perpendicular to the hub axis. The starter ring can be spaced axially from the hub sleeve so that the starter ring lies closely to the inner wall of the engine housing when the fan wheel is in the assembled condition. In this way, the starter ring can be driven in a simple manner by the starter pull-rope which is actuated from outside the housing. The starter ring is carried by a support shell which ensures the axial spacing of the starter ring from the hub sleeve. The starter ring can partially overlap the end section of the hub sleeve.
In an advantageous embodiment of the hub housing, the support shell of the starter ring rises axially from a disc which is formed by the mutually adjacent anchors.
The hub can be configured to have a conical shape and be mounted in the manner of a conical connection to the crankshaft. The end of the crankshaft is configured to have a corresponding conical shape. The conical hub is pretensioned with a tightening nut whereby the hub housing is fixed axially on the end of the crankshaft. In the hub, a slot can be formed in which an element can be placed which is fixed against rotation. This element engages in a corresponding slot in the crankshaft. Here, it is especially advantageous when a wedge-shaped raised portion is formed in the hub and this wedge can be brought into engagement with the slot in the crankshaft. The wedge is formed with the hub housing so that an especially simple assembly of the fan wheel is ensured.
REFERENCES:
patent: 2438669 (1948-03-01), Krenzke
patent: 3952712 (1976-04-01), Hermanson
patent: 5287832 (1994-02-01), Uhl
Andreas Stihl AG & Co.
Dolinar Andrew M.
Ottesen Walter
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