Front-wheel drive transfer case (PTU) with hydraulically actuated separation

Abstract

Arrangement for a passenger vehicle, normally having front-wheel drive and selectable four-wheel drive, the arrangement comprising: a transversely mounted transmission (7) in the vehicle, driven by a transversely mounted vehicle engine (8); a front axle differential (60) driven by the transmission (7), which has a front axle differential housing (100) extending transversely to the vehicle's main axis, the front axle differential (60) having front wheel shafts (64, 66) connected to first axle shaft gears for driving the front wheels (103, 113) of the vehicle; a rear axle drive shaft (110) connected to the front axle differential housing (100) and surrounding at least one of the front wheel shafts (64, 66); a rear axle drive pinion (120) rotatably mounted on the rear axle drive shaft (110) to engage a torsionally connected driveshaft (140). to drive;A rear axle differential (150) with a ring gear (146) torsionally connected to the driveshaft (140), the ring gear (146) being connected to a housing (152) having drive gears (154) that drive second axle shaft gears (156) connected to the rear wheel shafts, the rear wheel shafts driving the rear wheels (160) of the vehicle, the housing (152) also having a coupling connection (162) with one of the rear wheels (160), the rear axle differential (150) having a first operating state in which it differentially drives the rear wheels (160), and the rear axle differential (150) having a second state in which the housing (152) has a decoupled coupling connection (162) with one of the rear wheels (160) to allow the rear wheels (160) to be disengaged and in relation to to run freely towards each other;a shift sleeve (180) mounted in a frame of a power takeoff unit (170) to selectively couple the rear axle drive pinion (120) with the rear axle drive shaft (110); wherein the shift sleeve (180) has a first position in which it torsionally couples the rear axle drive pinion (120) to the rear axle drive shaft (110), and wherein the shift sleeve (180) has a second position in which it decouples the rear axle drive pinion (120) from the rear axle drive shaft (110); a hydraulic actuator (190) for displacing the shift sleeve (180) which includes a piston (194) which is mounted in the frame of the power takeoff unit (170), wherein the piston (194) has a seal (334) which separates an engagement pressure chamber (336) and a disengagement pressure chamber (342), wherein the piston (194), which has a buffer connection with the shift sleeve (180), is made of aluminium and the shift sleeve (180) is made of steel;a hydraulic pump (210) torsionally connected to and driven by the rear axle drive pinion (120) to drive the hydraulic actuator (190); and a pressure accumulator (230) fluidically connected to the pump (210) and the hydraulic actuator (190) to supply pressurized hydraulic fluid to the hydraulic actuator (190) when the rear axle drive pinion (120) is disengaged from the rear axle drive shaft (110).

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