| 摘要 |
<p>A center differential device (17) for use in a four wheel drive system, the device including a viscous coupling (29), a ball ramp actuator (31), and a clutch pack (33). Under normal driving conditions, most of the torque is transmitted to the front drive wheels (11), and the device (17) rotates as a unit. If the front wheels (11) begin to slip, the input shaft (15) and input coupling member (35) rotate faster than the output coupling member (43), thus transmitting torque to the output coupling member (43). This torque is transmitted to the first ramp plate (51) of the ball ramp actuator (31), displacing the actuator from its neutral position (FIG. 3), such that the second ramp plate (52) begins to load the clutch pack (33) and transmit torque from the housing (25) to the output shaft (19), and from there to the rear drive wheels (23). With the present invention, for any given mount of front wheel slip, a predetermined amount of torque may be transmitted automatically to the rear drive wheels (23), the viscous coupling (29) providing a "speed sensitive" input to the ball ramp actuator (31), without the need for any separate controls, sensors, etc. <IMAGE></p> |
