Endless belt power transmission systems or components – Pulley with belt-receiving groove formed by drive faces on... – Fluid pressure actuator for adjustment of member
Reexamination Certificate
1999-05-18
2001-02-20
Fenstermacher, David (Department: 3682)
Endless belt power transmission systems or components
Pulley with belt-receiving groove formed by drive faces on...
Fluid pressure actuator for adjustment of member
C474S029000
Reexamination Certificate
active
06190274
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a pair of conical disks (pulley halves) of a continuously variable cone-pulley transmission with pressure compartments that can be turned on and off.
Continuously variable cone-pulley transmissions are of high interest for use in motor vehicles, particularly passenger cars because, in addition to increased comfort (absence of gear-shift jolts) in comparison to automatic transmissions using hydrodynamic converters, they offer potential advantages in fuel consumption.
A pair of conical disks falling within the same category as the present invention is known from DE 195 44 644. The continuously variable cone-pulley transmission according to this publication has a pair of disks arranged on, and constrained to share the rotation of, the driving shaft and a pair of disks arranged on, and constrained to impart their rotation to, the driven shaft. The disk pairs each have an axially movable conical disk and an axially fixed conical disk. Between the two disk pairs, an endless-loop means in the form of a chain is provided for transmitting a torque. Transmissions of this kind may be subject to leakage losses, which can be harmful to their proper functioning.
OBJECT OF THE INVENTION
The object of the present invention is to further develop a conical disk pair of this kind so that it can be manufactured cost-effectively and works with a reduced amount of leakage losses.
SUMMARY OF THE INVENTION
The invention is embodied in a pair of conical disks (pulley halves) of a continuously variable cone-pulley transmission with means for switching a pressure compartment on and off dependent on the transmission ratio. The disk pair includes
a shaft to which a movable conical disk is attached in a manner that prevents rotational but permits axial relative movement and to which a fixed conical disk is solidly attached,
a pressure chamber formed between the movable conical disk and a ring-shaped component that is solidly attached to the shaft,
a first pressure compartment formed between the side of the ring-shaped component that faces away from the pressure chamber and a ring-shaped, piston-like part that is axially movable relative to the shaft and is acted upon by a force whose magnitude depends on the magnitude of the torque acting on the shaft, and
a second pressure compartment formed, likewise, between the ring-shaped component and the piston-like part.
The first pressure compartment is connected to a pump and has an outlet channel that is closed off by the piston-like part to an increasing degree when there is an increase in the torque. The movable conical disk has centering guide portions sliding in tight contact along the surface of the shaft and interacting with channel openings in the circumference of the shaft to form a valve arrangement. When the distance between the conical disks is large, the valve arrangement, through channels formed in the shaft, connects the second pressure compartment to a space outside of the shaft. When, on the other hand, the distance between the conical disks is small, the valve arrangement connects the second pressure compartment with the pressure chamber instead of the space outside of the shaft.
In accordance with one presently preferred embodiment of the improved transmission, the shaft is provided with an oblique bore hole running through the shaft at an oblique angle, starting from a place that is located on the circumference of the shaft and connected with the second pressure compartment. As a further characteristic of the preferred embodiment, the shaft is also provided with a tap hole leading into the oblique bore hole. In the case where the distance between the conical disks is large, the oblique bore hole leads to the space outside of the shaft and the tap hole is closed off. In the opposite case, when the distance between the conical disks is small, the oblique bore hole is blocked and the tap hole is connected to the pressure chamber.
It is advantageous if the aforementioned tap hole runs in a radial direction relative to the shaft.
In a further advantageous development of the invention, in place of one oblique bore hole and one tap hole, the shaft has two oblique bore holes that run all the way or at least almost all the way through the shaft and are connected with each other. At least one of them opens at both ends to the circumference of the shaft. In the case where the distance between the conical disks is large, the oblique bore holes connect the second pressure compartment to the space outside of the shaft, and a further opening of the oblique bore holes falls in between the centering guide portions of the movable conical disk. When, on the other hand, the distance between the conical disks is small, the movable conical disk closes off the bore hole opening to the space outside of the shaft and opens up the further bore hole opening, thereby establishing a connection to the pressure chamber.
In an advantageous variation of the immediately preceding arrangement, the two oblique bore holes run into each other inside the shaft. One of the oblique bore holes starts from a place that is located on the circumference of the shaft and connected with the second pressure compartment. The other oblique bore hole also opens at one end to the circumference of the shaft where, when the distance between the conical disks is large, it connects to the space outside of the shaft via an axial channel formed between the movable conical disk and the shaft and an axial groove formed in the shaft. In the opposite case, where the distance between the conical disks is small, the end of said other oblique bore hole opens into the pressure chamber, and the axial groove is closed off by the movable conical disk.
In another advantageous development of the invention, at the place where the channel from the second pressure compartment opens to the space outside of the shaft when the distance between the conical disks is large, an axial groove extends to the movable conical disk and an axial channel is formed between the movable disk and the shaft at an axial distance from the axial groove. In the case where the distance between the conical disks is small, the opening of the channel is closed off by the movable conical disk and the axial groove is connected to the pressure chamber via the axial channel and a further axial groove on the surface of the shaft.
In a further advantageous solution to the inventive problem, the channel formed in the shaft that connects the second pressure compartment to the space outside of the shaft when the distance between the conical disks is large ends in two axially offset bore holes that have openings to the outside, and a connector bore hole leads from the pressure chamber across the movable conical disk to the shaft. In the case when the distance between the conical disks is small, the inner of the two axially offset bore holes is closed off by the inner centering guide portion of the conical disk and the outer of the two axially offset bore holes is connected to the connector bore hole.
To the extent that the foregoing solutions include an axial groove, it is advantageous if the latter is formed in the area of the attachment that prevents rotational but permits axial relative movement between the movable conical disk and the shaft.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawing.
REFERENCES:
patent: 5803846 (1998-09-01), Yamada et al.
patent: 5879253 (1999-03-01), Friedmann et al.
Darby & Darby
Fenstermacher David
LuK Getriebe-Systeme GmbH
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