| 摘要 |
PROBLEM TO BE SOLVED: To smoothly carry out shifting by allowing shifting in a travel state on the operation of a hydraulic continuously variable transmission and a hydromechanical transmission, and by setting the shift delay time as the total time of an electrical delay and the delay of a mechanical part, and issuing a shifting instruction earlier by the total delay time. SOLUTION: A hydromechanical transmission(HMT) is formed out of a transmission 30 equipped with a hydraulic continuously variable transmission (HST) 21. When output rotation in the forward travel side is gradually increased, an HST mode is switched to an HMT mode at a certain point, and when the output rotation drops to or below a certain point, the HST mode is selected. For speed selection, electrical and mechanical delay times due to the shift with clutches 11, 12 are taken into consideration, and control is made for estimating the arrival point of shifting with the delay times used as a time count in a simulated calculation. Thus, the shifting can be made on optimum timing and a shock or the like does not take place. |
