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:
Jan. 08, 1991
Filed:
Jul. 10, 1989
Aisin AW Co., Ltd., , JP;
Abstract
A pressure control device of an automatic transmission in which duty ratio of speed gear changing solenoid is controlled, when a shift is done from D, 2 or L range to P, R or N range and back again to D, 2 or L range, such that the duty ratio is maintained at 0% to ensure a sufficiently large apply flow rate and then increased followed by a progressive decrease towards 0%. The time over which the duty ratio is maintained at 0% is shortened in an amount which is determined in accordance with the time elapsed till the shift back to the D, 2 or L range, whereby an abrupt application of the engaging hydraulic pressure to a clutch is avoided to minimize a shock which is generated at the time of shifting. When a shift is done for the first time from N to D range after turning on of the ignition switch, the time over which the duty ratio is maintained at 0% is prolonged so as to increase the rate of supply of the hydraulic oil to oil passages and hydraulic pistons of clutches for operating rotational elements of the automatic transmission, so that sufficiently large quantity of oil is maintained at the time of the first shift from N to D range shortly after the start of the engine, thereby minimizing a shock.