192 clutches and power-stop control – Clutches – Axially engaging
Reexamination Certificate
1999-11-29
2001-07-17
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Clutches
Axially engaging
C074S015860, C074S431000
Reexamination Certificate
active
06260682
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates in general to power take-off units for selectively providing power to a rotatably driven accessory provided on an engine driven vehicle. More specifically, this invention relates to a two-piece output bell gear assembly for use in a clutch assembly provided within such a power take-off unit.
Power take-off units are well known mechanical devices that are commonly used in conjunction with sources of rotational energy, such as vehicle engines and transmissions, for selectively providing power to one or more rotatably driving driven accessories. For example, power take-off units are commonly used in a variety of industrial and agricultural vehicles for operating hydraulic pumps that, in turn, operate hydraulically driven accessories, such as plows, trash compactors, lifting mechanisms, winches, and the like. The power take-off unit provides a relatively simple and inexpensive mechanism for supplying rotational power from the vehicle engine to operate the rotatably driven accessory.
To accomplish this, a typical power take-off unit includes a rigid housing having a mounting surface formed thereon. An opening is formed through a portion of the mounting surface of the power take-off housing. An input gear is rotatably supported within the housing and includes a portion that extends outwardly through the opening formed through the mounting surface. The mounting surface of the power take-off unit housing is adapted to be secured (typically by a plurality of bolts) to a corresponding mounting surface formed on a case of a transmission provided on the vehicle. An opening is also formed through a portion of the mounting surface of the transmission case. When the power take-off unit housing is secured to the transmission case, the input gear extends through the opening formed through the transmission case into meshing engagement with one of the transmission gears, typically a transmission gear that is driven by the vehicle engine. As a result, the input gear of the power take-of unit is rotatably driven whenever the vehicle engine is operated.
The power take-off unit typically further includes an output gear that is rotatably supported within the housing. The output gear meshes with the input gear such that the output gear is rotatably driven by the input gear whenever the vehicle engine is operated. The output gear is, in turn, connected to an output shaft that is rotatably supported on the power take-off housing. The output shaft extends outwardly from the housing of the power take-off unit and is adapted to be connected to the rotatably driven accessory. In some instances, the output gear is directly connected to the output shaft. In those instances, the output shaft is rotatably driven by the output gear whenever the vehicle engine is operated. In other instances, however, the output gear is connected through a clutch assembly to the output shaft. The clutch assembly is provided within the power take-off housing for selectively connecting the output gear to the output shaft and, therefore, permitting selective or intermittent operation of the rotatably driven accessory whenever the vehicle engine is operated.
In those power take-off units having a clutch assembly, the output gear is typically embodied as a bell gear including a gear portion and a bell portion. The gear portion of the output bell gear has a plurality of teeth formed thereon that mesh with corresponding teeth formed on the input gear. The bell portion of the output bell gear is generally hollow and cylindrical in shape and extends axially from the gear portion. The bell portion has a plurality of slots or similar structures that are adapted to engage corresponding protrusions or similar structures formed on a first plurality of clutch plates. In this manner, the first plurality of clutch plates is connected to the output gear for rotation therewith. A second plurality of clutch plates is splined onto the output shaft for rotation therewith. The second plurality of clutch plates are axially interleaved with the first plurality of clutch plates. An actuator is provided for selectively applying an axial force against the interleaved first and second pluralities of clutch plates. When such an axial force is applied, the first and second pluralities of clutch plates frictionally engage one another such that the output shaft is rotatably driven by the output bell gear. When such an axial force is not applied, the first and second pluralities of clutch plates do not frictionally engage one another, and the output shaft is not rotatably driven by the output bell gear.
In the past, the output bell gear has been formed from a single integral piece of material. Thus, the gear portion and the bell portion of the output bell gear have been formed as a single, unitary member. Although this structure has been effective, it has been found to be somewhat complicated in structure. As a result, traditional output bell gears are relatively difficult and expensive to manufacture. Also, as mentioned above, power take-off units are used to operate a wide variety of rotatably driven accessories. The nominal operating speeds of such rotatably driven accessories vary widely as well. To accommodate these different operating speeds for the rotatably driven accessories, it is known to construct power take-off units having differing overall speed reduction gear ratios between the input gear and the output shaft. The speed reduction gear ratio of power take-off units having the general structure described above is usually determined by the relative sizes of the input gear and the output bell gear. Thus, it is known to provide a plurality of differently sized output bell gears and to select a desired one of the plurality of output bell gears for use with the input gear in a given power take-off unit. In this manner, the speed reduction gear ratio of power take-off unit can be varied as desired. Unfortunately, it is costly and inefficient to manufacture such a large number of differently sized output bell gears and to maintain such output gears in inventory, particularly when the structures of such output bell gears are relatively complicated and expensive, as mentioned above. Thus, it would be desirable to provide an improved structure for a bell gear for use in a clutch assembly provided within a power take-off unit that minimizes the cost and expense of manufacture and inventory and that is more readily adaptable for varying the overall speed reduction gear ratio of the power take-off unit as desired.
SUMMARY OF THE INVENTION
This invention relates to an improved structure for a bell gear for use in a clutch assembly provided within a power take-off unit. The power take-off unit includes a rigid housing having an input gear rotatably supported therein. An output gear assembly is rotatably supported within the housing. The output gear assembly includes a toothed gear member and a bell member that are splined together. The toothed gear member meshes with the input gear such that it and the bell member are rotatably driven thereby. The bell member is selectively connected through the clutch assembly to an output shaft that is rotatably supported on the power take-off housing. The output shaft extends outwardly from the housing of the power take-off unit and is adapted to be connected to a rotatably driven accessory. The two-piece structure of the output gear assembly minimizes the cost and expense of manufacture and inventory and is more readily adaptable for varying the overall speed reduction gear ratio of the power take-off unit as desired.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.
REFERENCES:
patent: 2056050 (1936-09-01), Harris
patent: 2519279 (1950-08-01), Peterson et al.
patent: 2600108 (1952-06-01), Gerst
patent: 2736202 (1956-02-01), Wagner
patent: 3011608 (1961-12-01), Hansen
patent: 4378867 (1983-04-01), Pasqualucci
p
Raina Kudlip
Rang Brian L.
Bonck Rodney H.
Dana Corporation
MacMillan Sobanski & Todd LLC
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