| 摘要 |
<p>PCT No. PCT/EP85/00143 Sec. 371 Date Nov. 22, 1985 Sec. 102(e) Date Nov. 22, 1985 PCT Filed Apr. 1, 1985 PCT Pub. No. WO85/04697 PCT Pub. Date Oct. 24, 1985.A tractor power take-off drive line which includes a friction clutch (12) which is engaged by a fluid pressure operated actuator (12a) via a solenoid-operated valve (14). The engagement of the clutch is controlled by a system which includes a pulse width modulation function for providing a series of electrical pulses to the solenoid (14a) of the valve in successive predetermined time intervals during engagement of the clutch. Each pulse has an "on" period during which the valve connects the actuator to a source of pressurized fluid and an "off" period during which the valve connects the actuator to a dump line. Sensors (18,19) provide signals indicative of the input and output speeds of the clutch, and a micro processor control circuit (25) establish for successive time intervals the ratio between the intput and output speeds of the clutch and the change in this ratio by comparison with the ratio for a previous time interval. The control circuit compares the change in input to output speed ratio with a target change in this ratio set by the system for the respective time interval to produce an error signal, and uses this error signal to set the ratio of the "on" and "off" periods of the pulse width modulation function for the next successsive time interval. The control circuit also uses the value of the input to output speed ratio to determine the target change in the input to output speed ratio for the next successive time interval so as to adjust the clutch engagement pressure to tend to reduce the error signal to zero.</p> |
