The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 03, 1993
Filed:
Oct. 22, 1992
Yasunori Okura, Kanagawa, JP;
Kabushiki Kaisha Komatsu Seisakusho, Tokyo, JP;
Abstract
In a configuration in which electronically operated pressure control valves (31-36) are respectively connected to clutches of a two-stage transmission (3) composed of main transmissions (1st, 2nd, R, 4th, 3rd) and sub transmissions (L, H), when a downshift is effected from a present speed stage to a next speed stage with power on, the supply of oil pressure to a speed-changing clutch for the present speed stage is stopped on the basis of a speed-change command, the pressure control valve is actuated when a relative number of revolutions of the speed-changing clutch for the next speed stage becomes zero, which commences the supply of oil pressure to that speed-changing clutch, and the supply of oil pressure is gradually increased upon confirming the completion of a filling time of the speed-changing clutch. Thus discomfort owing to a speed-change shock is prevented in whatever state the amount of an accelerator operated and the state of operation of a brake are. In addition, in a downshift accompanying the operation of clutches of both transmissions, torque off time is not provided for the sub transmission clutch, and the supply of oil pressure to a next stage clutch is commenced immediately so as to supply oil pressure at a gradually increasing rate. After engagement of the clutch, the supply of oil pressure to the main transmission clutch at a gradually increasing rate is effected upon completion of the filling time, thereby preventing discomfort attributable to a speed-change shock.