Hydraulic torque vectoring differential
First Claim
1. A torque vectoring differential for a vehicle, comprising:
- an input bevel gear having a torque drive connection from a drive shaft of said vehicle for driving a transverse shaft;
said transverse shaft having right and left opposite ends, each of which is each coupled to and drives a ring gear of a respective right and left epicyclic gear set;
each of said right and left epicyclic gear set has a planet carrier coupled to a respective right or left wheel axle;
each of said right and left epicyclic gear set has a sun gear meshing with a torque plate of a respective right or left rotating bent-axis hydrostatic unit;
said hydrostatic units each having a displacement control for controlling the hydraulic displacement of said units;
a manifold between said hydrostatic units through which said hydrostatic units are hydraulically coupled;
whereby said differential operates like a conventional open differential in normal driving when said displacement of both hydrostatic units is setting equal, and torque biasing is achieved by setting said displacement of said hydrostatic units at differential displacements, wherein precise distribution of torque between the two wheels is determined by the relative displacement of said two hydrostatic units.
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Abstract
A hydraulic torque vectoring differential includes two epicyclic gear sets and two variable displacement hydrostatic units. Each hydrostatic unit is coupled to a reaction member of one of each of the epicyclic gear sets, each of which also has a first gear element coupled to an input drive shaft for power input from a prime mover of said vehicle and a third gear element coupled to an output shaft operatively driving the wheels of the vehicle. The hydrostatic units are hydraulically coupled so that hydraulic fluid pressurized in one hydrostatic unit drives the other hydrostatic unit, and fluid pressurized in the other hydrostatic unit drives the one hydrostatic unit. A control system controls the displacement of the variable displacement hydrostatic units. Power from the prime mover flows primarily through the epicyclic gear sets to the output shafts, and only differential power is passed through the hydrostatic units, thereby isolating the hydraulic units from the primary power flow and making use of low displacement hydrostatic units possible for said differential power flow through said differential. The desired torque distribution between the two wheels is determined by existing conventional computer controls based on inputs from known traction sensors.
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Citations
25 Claims
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1. A torque vectoring differential for a vehicle, comprising:
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an input bevel gear having a torque drive connection from a drive shaft of said vehicle for driving a transverse shaft;
said transverse shaft having right and left opposite ends, each of which is each coupled to and drives a ring gear of a respective right and left epicyclic gear set;
each of said right and left epicyclic gear set has a planet carrier coupled to a respective right or left wheel axle;
each of said right and left epicyclic gear set has a sun gear meshing with a torque plate of a respective right or left rotating bent-axis hydrostatic unit;
said hydrostatic units each having a displacement control for controlling the hydraulic displacement of said units;
a manifold between said hydrostatic units through which said hydrostatic units are hydraulically coupled;
whereby said differential operates like a conventional open differential in normal driving when said displacement of both hydrostatic units is setting equal, and torque biasing is achieved by setting said displacement of said hydrostatic units at differential displacements, wherein precise distribution of torque between the two wheels is determined by the relative displacement of said two hydrostatic units. - View Dependent Claims (2)
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3. A torque vectoring differential for a vehicle, comprising:
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two epicyclic gear sets, each having a first gear element coupled to an input drive shaft for power input from a prime mover of said vehicle;
two variable displacement hydrostatic units, each coupled to a second gear element of one each of said epicyclic gear sets;
an output shaft coupled to a third gear element of each of said epicyclic gear sets;
said hydrostatic units being hydraulically coupled so that hydraulic fluid pressurized in one hydrostatic unit drives the other hydrostatic unit, and fluid pressurized in the other hydrostatic unit drives the one hydrostatic unit; and
a control system for controlling the displacement of said variable displacement hydrostatic units;
whereby, power from said prime mover flows primarily through said epicyclic gear sets to said output shafts, and only differential power is passed through said hydrostatic units, thereby isolating said hydraulic units from said primary power flow and making use of low displacement hydrostatic units possible for said differential power flow through said differential. - View Dependent Claims (4, 5)
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6. A hydromechanical torque vectoring differential, comprising:
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a geartrain, including an epicyclic gearset, coupled between an input drive shaft and two output drive shafts, and also coupled to two variable displacement hydrostatic units that are hydraulically coupled together through flow channels, said gear train being configured such that said hydrostatic units react a ratio of the input torque and rotate and cause fluid flow only when there is a differential wheel speed;
whereby, only differential shaft speed power is transmitted to the hydrostatic units. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A hydrostatic unit for operation as a hydraulic pump or for operation as a hydraulic motor, comprising:
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a cylinder block having axial cylinders and pistons mounted in said cylinders, said pistons having hollow piston rods protruding from one end of said cylinders;
a torque plate supported in torque plate bearings for rotation about a central torque plate axis, said torque plate having one face in rotating sliding engagement with a hydraulic manifold, and having an opposite face engaged with said protruding ends of said piston rods in alignment with openings through said torque plate for transfer of fluid to and from said cylinders and said manifold, by way of said hollow piston rods and said torque plate openings;
said cylinder block having a cylinder block axis of rotation that is adjustable with respect to said torque plate axis for changing displacement of said hydrostatic unit;
said torque plate having a coaxial spur gear on an outer diameter of said torque plate and in gear mesh with a torque transfer gear for input or output of torque to or from said hydrostatic unit;
said gear mesh being orientated such that radial force exerted by said torque transfer gear partially offsets and reduces radial loads exerted on said torque plate from said pistons.
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23. A process for vectoring torque from an input shaft to two output shafts, comprising:
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inputting torque from a drive shaft via a pair of bevel gears to input elements of two epicyclic gear sets;
driving two output shafts with output torque from output elements of said two epicyclic gearsets;
reacting said output torque in said epicyclic gearsets via third elements of said epicyclic gearsets to a pair of hydraulically coupled variable displacement hydrostatic units; and
varying the displacements between said two hydrostatic units to vary the torque bias to either output shaft. - View Dependent Claims (24, 25)
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Specification