Endless belt power transmission systems or components – Pulley with belt-receiving groove formed by drive faces on...
Reexamination Certificate
1998-12-24
2001-02-13
Bucci, David A. (Department: 3682)
Endless belt power transmission systems or components
Pulley with belt-receiving groove formed by drive faces on...
C474S069000, C474S070000, C474S013000, C474S017000
Reexamination Certificate
active
06186915
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns a steplessly variable pulling means transmission in which the variation in the transmission ratio is effected by varying the operative diameter of at least one of the pulling means pulleys over which the pulling means runs.
2. Description of the Related Art
The pulling means used can be a belt. For example a V-belt or a round belt. As well as a chain or another link-type belt or band member.
The pulling means pulleys are adapted to the respective pulling means used. In which respect. Particularly when employing round belts and V-belts. Pulleys are used whose substantially axially oriented pulling means running surfaces are slightly inclined with respect to the plane in which the endless pulling means circulates. Those pulling means pulleys whose operative diameter is variable for the purposes of varying the transmission ratio are referred to as adjusting pulleys.
In that respect it is known in the case of the described conical pulling means running surfaces for the adjusting pulley to be composed of two pulley halves which are arranged on respective sides of the plane of the pulling means and the axial spacing of which is variable whereby the operative diameter of that adjusting pulley can also be altered, by virtue of the conical configuration of the running surfaces.
It is likewise also possible for the operative diameter to be varied without axial movement, just by radial movements of the adjusting pulley, for example by virtue of the adjusting pulley being formed by segments which are possibly in mutually overlapping relationship and which are pivotable in the plane of the pulling means or which are displaceable radially relative to the axis of the adjusting pulley.
The simplest form of a pulling means transmission comprises two pulleys, over which the endless pulling means is guided, at least one of the pulleys being in the form of an adjusting pulley.
To increase the transmission ratio range, the pulling means transmission may comprise a plurality of, for example, two, pulling means which are then passed over a total of at least four pulleys. In such a situation, one belt pulley of the one pulling means is frequently carried on the same axis as a pulling means pulley of the other pulling means and is non-rotatably connected thereto, being for example of an integral construction in the form of a double pulley, as can be seen for example from DE 38 25 091.
However, it is precisely those adjusting pulleys which are varied in terms of their operative diameter by axial displacement of the pulley halves of the adjusting pulley that suffer from the problem that the plane of the pulling means is axially displaced when one pulley half is fixed and one pulley half is axially displaceable. If in that case the other pulley results in the pulling means extending in an inclined position, with the consequence of defective traction and in particular increasing wear on the pulling means.
Therefore, the attempt has already been made in DE 38 25 091 to eliminate that axial displacement by simultaneous axial movement of the carrier on which the adjusting pulleys are disposed. That however entails additional structural expenditure and also means that the adjusting pulleys are mounted in a movable member, that is to say in this case in the variator or variable speed unit, although for other reasons, for example to minimize structural size, it would be desirable if possible for the pulleys of the variator unit to be in the form of fixed pulleys which are not variable in respect of their diameter.
BRIEF SUMMARY OF THE INVENTION
The object in accordance with the present invention is to provide a pulling means transmission which is simple and inexpensive to produce and in terms of its structure and to afford a minimum possible structural space with the largest possible band width in respect of the transmission ratio.
The fact that, within the pulling means transmission, the one or more adjusting pulleys are symmetrically pre-stressed with respect to the plane of the pulling means which runs thereon, means that, upon a variation in the operative diameter of that adjusting pulley, there is no axial displacement of the pulling means and thus no undesirable increase in wear on the pulling means, nor is there any need to compensate for the axial displacement of the pulling means by way of the belt pulleys. In accordance with the invention, when the transmission involves axial pre-stressing of axial pulley halves which make up an adjusting pulley, both pulley halves are pre-stressed in the same manner, that is to say by the same amount and with mutually opposite pre-stressing directions.
In the case of such an adjusting pulley which is composed of pulley halves, the pre-stressing direction is always directed in the direction of the largest operative diameter as otherwise there is no traction effect as between the pulling means and the adjusting pulley. The same applies in regard to an adjusting pulley which is to be varied by radial displacement.
The pre-stressing is effected for example by means of spring force, but it can also be achieved by the pressure of a fluid, that is to say a hydraulic oil or a gas or by magnetic force.
If the pulling means transmission includes two pulling means, wherein two of the pulleys, of which there are then at least four, run on a common axis or shaft, in particular in the form of a double pulley, a preferred embodiment of the invention provides that, of the pulling means pulleys of which there are then a total of at least four, the two outer pulleys which are associated with different pulling means are in the form of adjusting pulleys and the two pulleys which run on an axis or shaft and which are disposed therebetween and which run on a common axis or shaft and which can be moved to and fro jointly in respect of their position between the two outer pulleys are in the form of fixed pulleys, preferably in the form of a double pulley.
That has the advantage that this so-called variator or variable speed unit which includes the two central pulleys, apart from its pivotability, does not have to embrace any further functions such as for example displaceability of the pulleys, and therefore does not become unnecessarily complicated and large. Instead, there is in any case more structural space available in the case of the outer pulleys as the axis of rotation thereof does not have to be displaceable with respect to the surrounding housing so that, at those outer pulleys, it is also easier to provide them in the form of an adjusting pulley.
An embodiment in accordance with the invention is described in greater detail by way of example hereinafter with reference to the drawings in which:
REFERENCES:
patent: 3863514 (1975-02-01), Jensen
patent: 4310082 (1982-01-01), Elmy et al.
patent: 4605386 (1986-08-01), Harris
patent: 4813921 (1989-03-01), Dianda
patent: 4832661 (1989-05-01), Wagner et al.
patent: 4838834 (1989-06-01), Miyata
patent: 5387052 (1995-02-01), Artzberger
patent: 282311 (1988-09-01), None
patent: 2780128 (1988-09-01), None
Bucci David A.
Charles Marcus
Ruey-Zon Chen
Thorp Reed & Armstrong LLP
LandOfFree
Steplessly variable V-pulley looping transmission does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Steplessly variable V-pulley looping transmission, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Steplessly variable V-pulley looping transmission will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2597123