US 5,469,754 AGranted

Control apparatus for hydraulically operated vehicular transmission

AssigneeHonda Giken Kogyo Kabushiki Kaisha

InventorsTakafumi Sakai, Hideki Wakamatsu, Yoshihiro Tsuboi, Masaya Kawauchi

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Abstract

The transmission is of a type that a low-speed transmission train is established in cooperation with one-way clutch. A high-speed transmission train is established by hydraulic oil supply via a shift valve in a condition in which the hydraulic oil is kept supplied to the low-speed hydraulic engaging element. A pressure adjusting valve and a hydraulic oil pressure control valve control, to increase or reduce, the supply pressure of the hydraulic oil to the high-speed hydraulic engaging element. A speed change controller at an initial stage maintains the shift valve, at the time of speed changing from a high-speed transmission train to a low-speed transmission train, in a condition in which the hydraulic oil is supplied to the high-speed hydraulic engaging element. The supply pressure of the hydraulic oil is reduced in this condition until the high-speed hydraulic engaging element gives rise to a slip. The supply pressure of the hydraulic oil is maintained in the condition of reduced pressure until the one-way clutch is engaged and thereafter the shift valve is changed over to a condition in which the hydraulic oil is discharged from the high-speed hydraulic engaging element.

Claims3

Dependent claims

A control apparatus for a hydraulically operated vehicular transmission having a hydraulic engaging element for a low-speed transmission train so as to establish the low-speed transmission train in cooperation with a one-way clutch, and a hydraulic engaging element for a high-speed transmission train, said apparatus having a shift valve for controlling supply and discharge of hydraulic oil to and from the hydraulic engaging element for the high-speed transmission train such that the high-speed transmission train can be established by hydraulic oil supply via said shift valve in a condition in which the hydraulic oil is kept supplied to the hydraulic engaging element for the low-speed transmission train, said apparatus comprising:

hydraulic oil pressure control means which can control to increase or reduce a supply pressure of the hydraulic oil to the hydraulic engaging element for the high-speed transmission train;
and
speed change control means so arranged and constructed that, at a time of speed changing from the high-speed transmission train to the low-speed transmission train, said shift valve is maintained at an initial stage in a condition in which the hydraulic oil is supplied to the hydraulic engaging element for the high-speed transmission train, that the supply pressure of the hydraulic oil is reduced in this condition until the hydraulic engaging element for the high-speed transmission train gives rise to a slip, that the supply pressure of the hydraulic oil is maintained in the condition of reduced pressure until said one-way clutch is engaged, and that thereafter said shift valve is changed over to a condition in which the hydraulic oil is discharged from the hydraulic engaging element for the high-speed transmission train.

Dependencies are inferred from the claim text.