Abstract: A slip control mechanism comprises a throttling path with a cross-sectional area variable according to the relative displacement of an output element of a torque converter and an output shaft. The throttling path is in communication via a fluid passage with a disengagement chamber opposing one side of a friction clutch. The other side of the friction clutch faces an engagement chamber. The disengagement chamber and the engagement chambers are so arranged as to control slippage of the friction clutch by pressure balance therebetween. The throttling path is formed in a specific geometry which assures moderate changes in the pressure balance between the disengagement chamber and engagement chamber in an intermediate throttling range. In the preferred construction, the throttling path is so constructed that the rate of change of the throttling cross-sectional area satisifes the inequalityd.sup.2 S/dx.sup.2 .gtoreq.

Abstract: A torque transmission through the hydrodynamic drive is directly measured by a torque sensor and a desired torque transmission is obtained for operating condition of a prime mover. The clutch slip of a lock-up clutch is adjusted toward a value where the measured torque transmission agrees with the desired torque transmission.

Abstract: In an automatic transmission for an automotive vehicle, an operating area covered by a high gear ratio is extended toward low vehicle speed side and the high gear ratio is released in response to the opening degree of the throttle and vehicle speed. The high gear ratio is released when the vehicle speed value is lower than a predetermined vehicle speed value and the opening degree of the throttle is larger than a predetermined opening degree.

Abstract: A torque converter having an engine-driven pump impeller fastened to an input shell and a fluid-driven turbine runner mounted on an output shaft is equipped with a fluid-operated lockup clutch for providing a direct mechanical drive between the input shell and the output shell. The lockup clutch is maintained in a slipping engagement condition in an intermediate speed range. This slipping engagement is controlled by a variable fluid passage whose opening size is determined by an axial position of the turbine runner relative to the output shaft. The turbine runner is rotatable and axially movable relative to the output shaft. The turbine runner and the output shaft have, respectively, flanges which rotates side by side. There are formed, between the flanges, a plurality of pockets which are circumferentially arranged. Each pocket has contoured surfaces, and confines a ball.

Abstract: A lock-up control system for a lock-up type automatic transmission of an automotive vehicle.The lock-up control system functions to temporally release lock-up operation of a torque converter of the transmission upon occurrence of a gear shift signal even if the automotive vehicle is operating within any one of lock-up ranges. Gear shifting detector means generates a gear shift signal having a time duration which is variable corresponding to the time duration of a corresponding gear shifting operation. The duration of the gear shift signal generated by the gear shifting signal may also be variable also with the magnitude of engine load.

Abstract: A fuel cut-off control can prolong a period of time in which the engine speed is maintained at a range suitable for performing fuel cut-off and shorten a period of time in which the engine speed is in a fuel recovery range to minimize fuel consumption during engine deceleration. In a fuel cut-off control system in a fuel injection internal combustion engine with an automatic transmission, the fuel cut-off control system is responsive to a brake switch signal and an engine speed signal having a value above a fuel recovery threshold to decrease the value of a fuel cut-off threshold to again perform the fuel cut-off even in the normal fuel recovery range. Down shifting of a transmission gear is performed to increase engine speed to a level beyond the fuel cut-off threshold to prolong the fuel cut-off period.

Abstract: A hydraulic control type automatic transmission includes at least one shift valve (131, 132) which operates in accordance with a predetermined relation between the vehicle speed and the engine load to selectively supply hydraulic pressure to a plurality of friction elements (104, 105, 106, 107) to engage and disengage the friction elements. The automatic transmission further includes shift valve operation detecting switches (41, 42, 43, 44; 46, 47, 48; 229, 230) each of which are directly responsive to the displacement of a spool (160, 164) of the shift valve and produces electric output signal representing the operating condition of the shift valve just before the actual engagement or disengagement of the friction element or elements. The signal may, for example, be used to release a direct clutch (5) during the shifting operation.

Abstract: A lock-up control system is disclosed wherein the lock-up state of a torque converter is temporally released during gear shifting operation in an automatic transmission even if an automotive vehicle is operating in a predetermined lock-up range. A sensor generates an oil temperature compensation signal indicative of the temperature of oil used in the automatic transmission. The time duration of temporary release of the lock-up state is variable with variation in the oil temperature compensation signal.

Abstract: A lock-up control device in which a pulse train is generated which has a duration which increases as the vehicle speed decreases. A counter generates a period indicative signal indicative of a current period of the pulse train. A memory stores the period indicative signal for a preceding period. An adder generates an adder signal indicative of the addition of a preset value to the period indicative signal stored in the memory. A comparator compares the adder signal with the period indicative signal generated by the counter and generates a comparator signal when the former is larger than the latter. A flip-flop generates a flip-flop signal when the comparator signal occurs under the presence of a lock-up signal. An AND gate provides a lock-up release signal when said flip-flop signal occurs irrespective of the presence of the lock-up signal.

Abstract: The lock-up control system stores lock-up speed values for each gear position of the transmission. These values are compared against actual vehicle speed to control lock-up of the transmission. In the system, a counter receives clock pulses from a clock and sensor pulses from a vehicle speed sensor. The sensor pulses have a frequency indicative of information related to vehicle speed. The counter counts sensor pulses within a time interval between two adjacent clock pulses. This count is therefore indicative of vehicle speed.

Abstract: An automatic transmission is changed from the highest gear ratio to the next lower gear ratio upon depressing the brake pedal after the accelerator has been released to cause the automotive vehicle to begin a coasting operation as long as the engine speed is higher than a predetermined engine speed. As a result the engine speed increases, resulting in an increase in the time period when the engine speed remains above the predetermined engine speed to enhance the time period of the operation of fuel cut means, thereby improving fuel economy.

Abstract: A lock-up control system for a lock-up type automatic transmission.A load detection circuit generates a reference acceleration signal that indicates a reference acceleration, and an actual acceleration signal that indicates an actual acceleration of an automotive vehicle. The circuit compares the actual acceleration signal with the reference acceleration signal for generating a first command signal when the actual acceleration signal is greater than the reference acceleration signal and generating a second command signal when the actual acceleration signal is smaller than the reference acceleration signal. The first command signal is fed to a first vehicle speed comparator means to render it operative. The second command signal is fed to a second vehicle comparator means to render same operative.