Planetary gear transmission systems or components – With means to vary drive ratio or disconnect drive – Gear shiftable axially to disconnect or vary ratio
Reexamination Certificate
2000-02-23
2001-06-26
Estremsky, Sherry (Department: 3681)
Planetary gear transmission systems or components
With means to vary drive ratio or disconnect drive
Gear shiftable axially to disconnect or vary ratio
Reexamination Certificate
active
06251040
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a gear arrangement for domestic use, particularly for kitchen appliances, having an input shaft at the driving end and an output shaft rotatably connected to a working part at the driven end, there being arranged between the input shaft and the output shaft a planet gear train comprising at least one planet gear, a sun gear meshing with said planet gear and a ring gear meshing with said planet gear, said planet gear being in meshing engagement with the input shaft on the one side and in rotary engagement by way of its axle bearing with the output shaft on the other side.
Planet gear trains, also referred to as epicyclic gear trains, are generally known and described in “Meyers Grosses Taschenlexikon”, Volume 17, 1983, Bibliographisches Institut, Mannheim/Zürich or in “Meyers Lexikon der Technik und der exakten Naturwissenschaften”, 3rd Volume, Bibliographisches Institut, Mannheim/Zürich, for example.
Planet gear trains are characterized in that at least one gear, called the planet gear, rotates not only about its own axis but also revolves with this axis around another gear, called the sun gear, and that, in addition, the planet gear meshes with this sun gear and an outer ring gear. If two of these three components, i.e., the planet gear, the sun gear and the ring gear, are held stationary, the third component executes a compulsory movement. Conventionally, use is made of three planet gears revolving around the sun gear and held in a common planet carrier. With the size of the individual gears suitably selected, it is possible to obtain commensurate speed increasing or speed reducing ratios between the input shaft and the output shaft, for example, between the shaft of the sun gear and the shaft of the planet carrier.
A planet gear train has already been used in a processing tool for preparing food, as disclosed in EP-B1 0 292 664. The processing tool known from EP-B1 0 292 664 is of the type used for mixing and kneading food ingredients. The processing tool comprises a working shaft adapted to be driven by an electric motor of a kitchen machine. The actual housing of the processing tool is shaped to serve simultaneously as the mixing and kneading tool. In the area of its upper end the housing is driven by way of a planet gear train, at its lower end it is in sliding contact with a bearing block. The upper end of the processing tool is rotatably held in a receiving container of the kitchen machine. In driving mode the housing, which serves simultaneously as the processing tool, is rotated by way of the planet gear train to perform a mixing and kneading movement.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a gear arrangement for domestic use, particularly for kitchen appliances, such that its speed increasing or speed reducing ratios can easily be changed in at least two stages in order to enable the drive conditions of an appliance fitted with the gear arrangement to be adapted to the desired working conditions, whereby it should be a simple matter to change between the two different drive conditions.
Proceeding from a gear arrangement with the features initially referred to, this object is accomplished in accordance with the present invention by the planet gear and the ring gear having several gear pairs of various diameter and by the ring gear being displaceable in an axial direction so that in the one operating position the gear pairs of larger diameter are in meshing engagement, while in the other operating position the gear pairs of smaller diameter are in meshing engagement. With the at least one planet gear and the ring gear each having at least two toothed rings of various diameter and with the ring gear being displaceable in an axial direction, thus enabling the toothed rings of larger diameter to be brought into meshing engagement in one operating position while enabling the toothed rings of the other, smaller diameter to be brought into meshing engagement in the other or a further position, it is possible to set up at least two or more different transmission ratios. The number of gear stages depends on the number of interacting pairs of gear. When a particular gear stage is being set, however, the other gear pairs need not be in mesh. Preferably there are two pairs of gear, meaning two changeable gear stages.
Thanks to the displaceable arrangement of the ring gear, which forms the outer body of the gear arrangement, the displacement needed to change the drive conditions can easily be made from the outside of a housing, thus resulting in a sturdy and operationally reliable arrangement. By contrast the gears, meaning the planet gear or planet gears and the sun gear, can be arranged in a fixed configuration relative to each other.
In a preferred embodiment of the gear arrangement, in operation the axially displaceable ring gear is non-rotatably associated with the housing of the appliance, i.e., it is fastened in the housing such that it is displaceable only axially between the two different mesh positions. If the sun gear, which can be mounted directly on an input shaft, is driven in this arrangement, the planet gear between the sun gear and the ring gear will revolve as the result of being accordingly meshed with them and will drive, by way of its axle bearing, an output shaft which is connected to said bearing and can be constructed as a hollow shaft.
For a uniform transmission of force between the sun gear and the ring gear it is preferable to provide three planet gears in accordance with one aspect of the invention. Such planet gears are arranged uniformly in the space between the sun gear and the ring gear, i.e., with the axles of their axle bearings set at an angle of 120 degrees relative to each other.
According to another aspect of the invention, the input shaft is passed through the gear arrangement such that it can be connected with a processing tool at the opposite end in order, with two pairs of gears, to provide a further drive with a different speed yet same speed of input shaft in addition to the two different speed increasing or speed reducing ratios produced by the respective two toothed rings of the planet gear or planet gears and the ring gear.
To enable coupling with the first output shaft as well as with the second output shaft by simple coupling means it has proven to be preferable for the first output shaft to be constructed in sleeve shape involving the form of an externally or internally toothed sleeve which concentrically encompasses the second output shaft formed by the extended section of the input shaft. In this arrangement the second output shaft is preferably equipped with axially extending teeth so that a suitable working element can be plugged on these teeth, whereas the first output shaft has an elongated toothing on its radially outer side in order to plug on a driving element without interacting with the toothing of the second output shaft.
To ensure an exact displacement of the ring gear it is desirable to use a displacement device having a cam that engages in a corresponding cam track of a housing. Movement of the displacement device in axial direction causes the cam to move along the cam track, such that the ring gear is thereby displaceable axially in the direction of its center axis in the two operating positions in order to mesh with the larger or smaller toothed rings of the planet gear and the ring gear.
Simple guidance of the ring gear for its axial displacement is achieved by a tongue and groove arrangement. This arrangement preferably extends parallel to the axial direction of the planet gears.
For the ring gear displacement to be performed with good handling convenience, the displacement device includes a manipulating element comprising the cam or the cam track and being rotatably guided relative to the ring gear. In a further aspect of this arrangement it is desirable for the manipulating element to incorporate the at least one cam. Said cam can then be guided in a corresponding groove constructed as the cam guiding track of a housin
Agell Josep
Masip Josep-Maria
Penaranda Mariano
Rebordosa Antonio
Safont Vicenc
Braun GmbH
Estremsky Sherry
Fish & Richardson P.C.
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