Torque management unit with integrated hydraulic actuator

Abstract

The present disclosure provides an improved, integrated electronically controlled hydraulic-based torque distribution system and related method. The torque distribution system of the present disclosure includes an electric motor that drives a pump that generates hydraulic pressure used to selectively activate a clutch pack to transfer torque to the wheels of a motor vehicle.

What is claimed is: 
     
         1 . A torque management system for a motor vehicle comprising:
 a differential cover configured to enclose a vehicle differential, wherein the differential cover defines a lower hydraulic reservoir;   an electric motor mounted to the differential cover;   a hydraulic pump driven by the electric motor located in the lower hydraulic reservoir;   a pressure regulating valve located in the lower hydraulic reservoir and arranged in fluid communication with the hydraulic pump;   a hydraulically driven piston that extends and retracts based on hydraulic pressure; and   a clutch pack assembly configured to be progressively engage based on the position of the hydraulically driven piston.   
     
     
         2 . The system of  claim 2 , wherein torque transfer to a vehicle wheel is controlled by a pressure regulating valve downstream of the hydraulic pump that controls the hydraulic pressure acting on the hydraulically driven piston. 
     
     
         3 . The system of  claim 2 , wherein the electric motor is configured to be activated to maintain a desired target hydraulic pressure. 
     
     
         4 . The system of  claim 2 , wherein the clutch pack is configured to lock the rotation of a left wheel of a motor vehicle with an opposed right wheel of the motor vehicle when fully engaged. 
     
     
         5 . A torque management system for a motor vehicle comprising:
 a main differential cover that includes a cavity-defining portion that defines a cavity, wherein the cavity corresponds to a hydraulic reservoir;   a reservoir cover that mounts to the main differential cover, the reservoir cover covering the cavity to enclose the hydraulic reservoir when the reservoir cover is mounted to the main differential cover;   a clutch pack housed within the main differential cover, the clutch pack being positioned at the first side of the main differential cover;   a piston for compressing the clutch pack, the piston being housed within a piston chamber defined by the main differential cover, the piston being positioned at the first side of the main differential cover;   a hydraulic pump for generating hydraulic pressure that is applied to the piston to compress the clutch pack, the hydraulic pump having an outlet in fluid communication with the piston chamber when the reservoir cover is mounted to the main differential cover, the hydraulic pump having an inlet in fluid communication with the hydraulic reservoir, the hydraulic pump being carried with the reservoir cover; and   an electric motor for driving the hydraulic pump, the electric motor being carried with the reservoir cover.   
     
     
         6 . The system of  claim 5 , further comprising:
 an axle module housing;   a differential positioned within the axle module housing, the differential having a differential casing that is rotatable relative to the axle module housing about an axis;   an output shaft coupled to the differential, the output shaft being aligned along the axis;   wherein the main differential cover mounts to the axle module housing, the main differential cover having a first side and an opposite second side, the first side of the main differential cover facing toward the axle module housing when the main differential cover is mounted to the axle module housing, the second side facing away from the axle module housing when the main differential cover is mounted to the axle module housing, the main differential cover including a main body having a peripheral flange that defines a main outer boundary of the main differential cover, the main differential cover defining a shaft opening for receiving the output shaft, the main differential cover, and wherein at least a first portion of the hydraulic reservoir extends radially outside the main outer boundary;   a shaft bearing positioned within the shaft opening and is configured to allow the output shaft to rotate about the axis relative to the main differential cover;   wherein the clutch pack is configured to control the relative rotation between the differential casing and the output shaft when compressed.   
     
     
         7 . The system of  claim 6 , wherein the hydraulic pump is mounted on the reservoir cover and the electric motor is mounted on the hydraulic pump. 
     
     
         8 . The system of  claim 7 , wherein the reservoir cover includes a first portion that radially overlaps the main body of the main differential cover and a second portion that projects radially outwardly from the main body of the main differential cover, and wherein the hydraulic pump is mounted on the first portion of the cover. 
     
     
         9 . The system of  claim 8 , wherein the first portion of the hydraulic reservoir corresponds to a majority of a total volume of the hydraulic reservoir. 
     
     
         10 . The system of  claim 9 , wherein a second portion of the hydraulic reservoir is located radially inside the major outer boundary. 
     
     
         11 . The system of  claim 6 , wherein fastener openings are defined through the peripheral flange for receiving fasteners used to secure the main differential cover to the axle module housing. 
     
     
         12 . The system of  claim 11 , wherein the cavity-defining portion of the main differential cover defines a projection that extends into the cavity, and wherein at least one of the fastener openings is defined through the projection. 
     
     
         13 . The system of  claim 12 , wherein the reservoir cover defines a fastener access opening that aligns with the fastener opening defined by the projection. 
     
     
         14 . The system of  claim 6 , wherein the reservoir cover, the clutch pack and the piston are carried with the main differential cover when the main differential cover is removed from the axle module housing. 
     
     
         15 . The system of  claim 6 , wherein the main differential cover can be removed from the axle module housing without removing the reservoir cover from the main differential cover. 
     
     
         16 . The system of  claim 6 , wherein the reservoir cover, the hydraulic pump and the electric motor can be removed as a unit from the main differential cover without removing the main differential cover from the axle module housing. 
     
     
         17 . The system of  claim 6 , wherein the hydraulic pump and the electric motor can be removed from the reservoir cover without removing the reservoir cover from the main differential cover and without removing the main differential cover from the axle module housing.