Precession modulated transmission

Abstract

This invention pertains to a continuously variable differential transmission utilizing an axial array of dampers to induce and control the gyration frequency of a precessing plate. This mechanism consists of an input shaft driving a core group containing an axial array of dampers peripherally engaging a more-or-less axis symmetric Precession Plate, in a torsionally rigid fashion. This arrangement is coaxially disposed within a Transfer Case by a means allowing free rotation about a common central axis. This Transfer Case Contains an Abutment plate that provides a plane skewed at a non-right angle from said common axis. Dampers of said Core Group induce said Plate to maintain contact with said Abutment. As such, rotation imparted to the input shaft induces a linear, axially directed motion upon the damper array. The torsional rigidity of this assembly combined with the positive extension force exerted by the dampers, insure the modulation plate maintains engagement of the skewed plainer surface presented by the Abutment plate. The forces there in incurred are counterbalanced by supporting the opposite end of the core assembly by an anti-friction means to counter the axial trust forces generated by the dampers. This arrangement results in the dampers, by their action upon the Abutment Plate via the precession plate, constitute the sole means for transferring rotational moments from the input shaft to the transfer case. As an antecedent to this arrangement, one may consider the expansible chamber axial piston motor. This device departs from said Art by permitting the Transfer Case to rotate with the Core Group as it is mounted to a grounded structure in a manner that allows free rotation. The ensuing reduction ratio so produced, is a function of input speed, damper rate and load. By providing a means to vary the damping rate of the damper array, it is possible to regulate the final drive ratio. This differential arrangement results in a Precession Plate that exhibits the motion of a gyroscope. Its rotational speed is dictated by the prime mover while the gyration component: Critically, rotating in the same direction, is modulated by the dampers. As the gyration component alone, is translated to the Transfer Case, and hence output, the relationship between the rotating moment and gyrating moment determines the reduction ratio.

What is claimed is:  
     
         1 . A continuously variable differential transmission comprising: 
 A torsionally rigid input assembly consisting of an evenly spaced c array of dampers that are oriented so their respective damping actions is parallel to the rotational axis, while rigidly secured on one end to a carrier plate, with the other end engaging a swash plate with a means of retention, that insure the swash plates centroid of gyration remains coincident with, and axially located on, a specific position on the center axis of this more or less axis symmetric assembly, supported by ant-friction means, to be disposed to the rotational input introduced by the prime mover;    a transfer case assembly that interfaces by anti friction means with the first units swash plate by an abutment plate, with said abutment plate providing a plane at a skewed angle that dictating said swash plates angle of repose, while first units damper array insuring a positive engagement between said interface and providing an output means collinear with first units input means;    means to maintain the collinear relationship of the combined assemblies axis of rotation so as to insure a rotational input to the input assembly imparts a sequential compression and relaxation of the dampers in the damper array, thereby imparting a rotation of the swash plate, the orientation of which is dictated by a output assemblies abutment plate, or, alternately inducing the output assembly to rotate with the input assembly in a direct 1:1 ration, or a combination of both scenarios in which case the swash plate exhibits a motion characteristic of a precessing body with the gyrational frequency some fraction of rotation frequency;    means to regulate the damper rate, of the damper array so to impart a common damping rate to the individual dampers in a concurrent fashion, as appropriate for a given operating mode;    
     
     
         2 . A continuously variable differential transmission according to  claim 1 , where the damping process is accomplished by hydraulic means that includes an array of piston dampers, displacing hydraulic fluid by their cycling action, with said fluid passing through a valve plate ported in a manner to divide the fluid flow into control and return circuits; 
 a valving means to regulate a pressure drop across these circuits;    a housing assembly that contains and supports the core and transfer case assemblies, while providing an atmospheric pressure reservoir for hydraulic fluids emanating from said assemblies, and equipped with rotary seals at input and output as necessary to insure said housing is, practically leak free;    means to regulate the internal damper pressure within said housing.    
     
     
         3 . A continuously variable differential transmission according to claims  1  and  2 ; 
 means to export the pressurized hydraulic fluid from control and return circuits by porting from the core assembly via a valve plate, through the transmission housing for control and/or conditioning and/or power to run auxiliary systems.