Abstract: During a shift operation, a time interval TT which is required to switch a mechanical gear ratio is detected. To bring it into coincidence with a reference value, the duty cycle with which a linear solenoid valve SL6 which determines a back pressure on an accumulator is energized is adjusted. The duty cycle is adjusted in accordance with an oil temperature, a throttle valve opening and a shift mode of an automatic transmission in order to prevent the occurrence of shift shocks as a result of a variation in the shift response of the automatic transmission from transmission to transmission or with time.

Abstract: An electronically controlled automatic transmission system for applying and releasing clutches and brakes when the gears for the speed ranges are to be shifted or changed in accordance with the drive torque of the engine. Each brake and clutch is controlled by a solenoid valve and a manual valve. The manual valves control the application of fluid pressure to the clutches and the brakes. Each manual valve has a separate solenoid valve which controls the manual valve in accordance with the detected value of the driving force of the engine. In addition, the automatic transmission system measures the number of revolutions of the input shaft to the automatic transmission after the clutches and brakes at the release side are released for a gear shift, and detects the acceleration of the number of revolutions of the input shaft of the automatic transmission.

Abstract: During a shift operation, a time interval TT which is required to switch a mechanical gear ratio is detected. To bring it into coincidence with a reference value, the duty cycle with which a linear solenoid valve SL6 which determines a back pressure on an accumulator is energized is adjusted. The duty cycle is adjusted in accordance with an oil temperature, a throttle valve opening and a shift mode of an automatic transmission in order to prevent the occurrence of shift shocks as a result of a variation in the shift response of the automatic transmission from transmission to transmission or with time.

Abstract: The rotational speed of an engine Ne and a drum rotational speed Nt of a clutch Cl are compared against each other to determine a power on/off. For a 2.fwdarw.3 and a 2.fwdarw.4 shift in the power off condition, a timing solenoid SL5 is turned on (duty cycle of 100%) to accelerate the termination of a preceding speed range, thus increasing a time delay between such termination and the activation of a new speed range to be established. For other shifts, a time difference between the termination of a preceding speed range and the activation of a new speed range to be established is adjusted, by energizing the solenoid SL5 in accordance with the throttle opening .theta. and the vehicle speed No such that SL5 is energized with a high duty cycle for a longer .theta. and with a low duty cycle for a smaller .theta..

Abstract: An apparatus and method for synchronizing shifting of a main transmission and a subtransmission, particularly in automatic transmissions having more than four speed ranges. Synchronism is achieved by initiating the shifting of the main transmission when the speeds of the input and output shafts of the main transmission achieve a predetermined relationship.

Abstract: For a 2.fwdarw.1 shift, a timing solenoid valve SL5 is maintained at a duty cycle of 0% (off) for an interval TE=1.5 sec from the initiation of the shift operation and then the duty cycle is changed to 100% (on) after the TE interval so that an oil pressure of a brake B.sub.2 is maintained low during the shift operation while the oil pressure is increased to a high oil pressure for transfer of a maximum torque used in the first speed range upon completion of the shift operation. In response to a switching of a shift lever from D or S range to L range, the timing solenoid valve SL5 is energized with a duty cycle of 100% (on) at 2 sec after such switching to provide a high oil pressure for transfer of the maximum torque, thus preventing a shift shock from occurring as a result of a switching from D or S to L range.

Abstract: A printed circuit board includes a substrate, a printed electric circuit pattern formed on the surface of the substrate, a plurality of land patterns formed on end portions of the printed electric circuit pattern, an isolation layer formed on the surface of the substrate and printed electric circuit pattern, an opening formed in the isolation layer about each land pattern, a plurality of electrical devices arranged on the land patterns and a plurality of markers printed on the surface of the isolation layer enclosing corresponding electrical devices.

Abstract: An electronically controlled automatic transmission system including an automatic transmission having a plurality of clutches and brakes activated by application of a fluid pressure to change the gear ratio by engagement and disengagement of the clutches and brakes, a fluid pressure switching device for controlling the application of the fluid pressure to the clutches and brakes, and an electronic controller for changing the engagement and disengagement of the clutches and brakes by driving the fluid pressure switching device in accordance with the running condition of the vehicle, the electronic controller also controlling the speed of engagement of a clutch or brake which is to be engaged. The electronic controller includes a torque sensor for detecting the torque of the output shaft of the automatic transmission, and an engagement speed correcting device for correcting the speed of engagement of a clutch or brake which is to be engaged on the basis of the detected torque.

Abstract: A hydraulic control apparatus for an automatic transmission has friction elements for performing a downshift by releasing one friction engaging element and engaging another. The apparatus includes duty control valves connected to the friction engaging elements, duty solenoid valves connected to oil lines for supplying pilot hydraulic pressure to the duty control valves, and control means. In a case where a release duty signal is outputted to one duty solenoid valve to control the pilot hydraulic pressure to thereby release the one friction engaging element, and downshift is a power-on downshift, the control means raises the duty ratio of the other duty solenoid valve to a predetermined valve to raise engaging hydraulic pressure supplied to the other friction element when rotational speed of the transmission input shaft is greater than a difference between the product of output shaft rotational speed and low-side gear ratio and a rotational speed commensurate with a delay in engine speed upturn.

Abstract: In a vehicle having a torque converter and a lock-up clutch for effecting engagement and disengagement between input and output shafts of the torque converter, an engine brake controlling apparatus provides engine brake control independently of vehicle speed and includes a device for detecting the number of revolutions of the input shaft of the torque converter; a device for detecting the number of revolutions of the output shaft of the torque converter; and a control device for allowing the lock-up clutch to be engaged when the number of revolutions of the output shaft has exceeded the number of revolutions of the input shaft and for releasing the lock-up clutch when brake operation is detected.

Abstract: An electronically controlled automatic transmission including an automatic gear shift for changing the gear ratio according to the coupling/decoupling of the brake and clutch, a hydraulic switch for controlling a hydraulic pressure exerted on the brake and clutch, a timer for setting a time of coupling/decoupling of the clutch and brake during a shifting period, a detector for detecting vehicle information, a time correcting device for correcting the set time according to the detected vehicle information, and an electronic control device for driving the hydraulic switch and for changing the state of coupling/decoupling. The electronic control device having a temperature detector for detecting the temperature of the working fluid of the hydraulic switch, and a feedback stop device for stopping the correction by the time correcting device when the temperature detector detects that the temperature of the working fluid is below a predetermined temperature.