Abstract: A forward clutch choke (251) having an internal long narrow path is provided in an oil path which feeds a clutch pressure (PFWD/C) to an oil chamber (604) of a forward clutch mechanism (6). The choke restricts a flow of the hydraulic oil into the oil chamber at a low temperature where the viscosity of the hydraulic oil is high to thereby increase a time required for the oil chamber to be filled with the oil, which prevents the clutch mechanism (6) from being engaged tightly in a short time to thereby prevent an instantaneous rise in the output shaft torque. Since the viscosity of the hydraulic oil is low at normal temperature and the choke functions as an orifice, the clutch mechanism is smoothly engaged tightly based on the operation of an accumulator concerned (FIG. 4).

Abstract: A transmission for a vehicle has a pair of input shafts and an output shaft parallel to the input shafts. A plurality of drive gears is installed on the input shafts, and a plurality of driven gears are installed on the output shaft and meshed with the drive gears, respectively. Gear selecting mechanisms is provided respectively on the shifting input shafts to select one of the drive gears. A power transmitting mechanism is installed to the input and output shafts to transmit power from one of the input shafts to the other input shaft. First and second clutches are installed to the input shafts, respectively to fix the drive gears on the input shafts by the engagement thereof. An idler gear driven by the power transmitting mechanism is installed to the output shaft. A third clutch installed to the output shaft as to be capable of fixedly connecting the output shaft and the idler gear.

Abstract: In solenoid control method and apparatus for an automatic transmission, a current signal varied in a stepwise manner is caused to pass through a filter having a predetermined transfer function, the current signal being inputted to a solenoid to drive a control valve by which a working oil pressure on at least one frictional element of the automatic transmission is controlled by reducing the working oil pressure to release the frictional element and the filter passed current signal is inputted to the solenoid to drive the control valve. The solenoid control method and apparatus described above are applicable to a change-over shift operation.

Abstract: A control system for controlling operation of a pre-charge system of an automatic transmission. The control system comprises a first section which receives first and second gear change instructions which are issued in succession. The first and second gear change instructions are of a type of needing an engaged condition of a same friction element. The control system further comprises a second section which, when the second gear change instruction is issued during a pre-charge period of the friction element which is needed by the first gear change instruction, extends the pre-charge period of the friction element to a time when a pre-charge period needed by the second gear change instruction lapses.

Abstract: A hydraulic control system controls a hydraulic pressure as a standby pressure in a period from an engagement start point at which an engagement instruction for engaging a friction element is started to an abutment start point at which an abutment between an input element and an output element is started. The hydraulic pressure supplied to at least one friction element is so increased as to switch the friction element from a disengagement state to an engagement state, thus transmitting a revolution of the input element of the friction element to the output element of the friction element. The hydraulic control system includes: a speed sensor for sensing a speed of the friction element; and a standby pressure increase section for increasing the standby pressure in accordance with the speed of the friction element sensed with the speed sensor.

Abstract: A lock-up control system for an automatic transmission including a torque converter and a lock-up clutch. The lock-up control system comprises an accelerator pedal depression amount sensor for detecting a depression amount of an accelerator pedal, and a controller. The controller includes an accelerator pedal movement speed calculating section for calculating a movement speed of the accelerator pedal. The controller includes a lock-up control section adapted to disengage the lock-up clutch in a condition in which a driving point of the vehicle is within a lock-up condition releasing region in a set lock-up schedule, and to engage the lock-up clutch in a condition in which the driving point is within a lock-up condition applying region.

Abstract: An automatic transmission has a low clutch that assumes its engaged condition at a plurality of lower gear positions of D-range and a high clutch that assumes its engaged condition at a plurality of higher gear positions of D-range, A hydraulic control system for the transmission comprises a hydraulic section that produces a line pressure; a solenoid valve that produces a solenoid pressure upon receiving a solenoid signal; a first pressure control valve that produces a first output pressure from the line pressure by using the solenoid pressure and the first output pressure as operation signal pressures, the first output pressure having a smaller gain with respect to the solenoid pressure; a second pressure control valve that produces a second output pressure from the line pressure by using the solenoid pressure and the second output pressure as operation signal pressures, the second output pressure having a larger gain with respect to the solenoid pressure; and a switching valve that selectively assumes a fir

Abstract: In a control device of an automatic transmission that controls a plurality of solenoid valves by an ATCU to thereby supply and release signal pressure for controlling friction elements according to selected gear positions, the solenoid valves generate a signal pressure to be supplied to the friction elements which are engaged at a predetermined gear position in a low speed gear position group, when the ATCU stops functioning while the vehicle is driven at a low speed gear position. Shift valves supply the signal pressure to the friction elements. If the ATCU stops functioning while a gear position in a high speed gear position group is selected, the shift valves supply a signal pressure generated by manual valve to friction elements which are engaged at a predetermined gear position in the high speed gear position group.

Abstract: A transmission unit for a hybrid vehicle includes a housing formed with a water jacket for cooling a stator of a motor. The water jacket includes a hollow annular passage having a water inlet and a water outlet. The water jacket has at least one uneven or depressed portion for avoiding an adjacent component. At the uneven portion, the cross sectional shape of the flow passage is varied gradually and smoothly so that the cross-sectional area of the flow passage remains constant. The water jacket further includes an inflow passage extending in a tangential direction to the water inlet, and an outflow passage extending in a radial direction from the water outlet.

Abstract: An internal gear oil pump made of Al alloys having less mutual damage property and superior wear resistance is provided. The internal gear oil pump has a casing with a gear compartment, a drive gear, and a driven gear, all of which are the structural members of the internal gear oil pump. The casing is constituted of an Al-alloy casting. The drive gear and the driven gear are constituted of a hot plastic working material of Al—Si alloy powder. The hot plastic working material is constituted of an Al—Si alloy having a structure in which unit crystal phases are dispersed in a base matrix by 10 to 40 area percent. by the structural observation with an optical microscope, the unit. crystal phases being harder than the base matrix. The base matrix is constituted of an Al—Si alloy which contains, on weight basis, 10% to 18% Si, 4% to 8% Fe, 1% to 3% Ni, 1% to 3% Cr, and the balance being Al and incidental impurities.

Abstract: A drum supporting structure in an automatic transmission has a drum support immovably installed in the transmission case. The drum support includes a cylindrical hollow shaft portion on which the drum is rotatably disposed and a circular wall portion which is concentrically and integrally formed on one end of the cylindrical hollow shaft portion. A first part of the circular wall portion is secured to the transmission case and has a plurality of hydraulic fluid passages defined therein, and a second, diametrically opposed part of the circular wall portion has a plurality of blind bores defined therein. The number of the blind bores is at least the same as that of the hydraulic fluid passages. With this arrangement, the circular wall portion and thus the drum supporting structure is able to have a well-balanced structure.

Abstract: A shift control system for an automatic transmission mounted on an automotive vehicle. The shift control system comprises a plurality of frictional elements including at least an engaging-side frictional element which is able to make a shift for the automatic transmission upon being engaged by increasing a hydraulic pressure of a hydraulic fluid to be supplied to the engaging-side frictional element.

Abstract: A starting shift control system for a continuously variable transmission is provided which includes a control unit having a high start judgement device for judging whether or not a high start in a high speed side gear ratio is caused on the basis of a comparison between the generated number of the input rotation pulses and the generated number of the output rotation pulses from the time a first vehicle starting operation is performed after start of a prime mover, and a high start control device for restricting downshifting from the high speed side gear ratio to a target gear ratio when a start of the vehicle is judged to be the high start. A starting shift control method is also provided.

Abstract: A control device of an automatic transmission has automatic shift ranges and manual setting ranges including a first speed gear position at which an engine brake is operable. The control device turns on all solenoid valves at the first speed gear position in the automatic shift driving range, turns on only the second and third solenoid valves at the first speed gear position in the manual setting range, and turns on at least one of the three solenoid valves in normal operation. This prevents a shock resulting from a shift and easily starts a vehicle even if all of the three solenoid valves supplying oil pressure to the first through third shift valves for changing gear positions are turned off. Oil channels are preset in such a manner as to achieve a high speed gear position if no oil pressure is supplied to all shift valves.

Abstract: In gear-shift control performed during normal travelling, a drive frequency of each solenoid valve is set to a higher one to suppress fluctuations or changes of a quantity or speed of a flow of a hydraulic oil concerned when the solenoid current is turned on/off to suppress fluctuations of the output hydraulic pressure. In start selection, the drive frequency of the solenoid valve is set to a lower one to reduce the number of times a plunger and a ball hit each other within the solenoid valve to reduce a sound produced by the operation of the solenoid.

Abstract: An automatic transmission, which has automatic shift ranges and manual setting ranges having a first speed gear position at which an engine brake is operable, is constructed in such a manner that a first friction element engaged at the first speed gear position and at a backward driving gear position is connected to a pressure regulating valve controlled by a timing solenoid valve. If a gear position is automatically shifted from a gear position at which the first friction element is unengaged to a gear position at which the first friction element is engaged, the timing solenoid valve is kept on for a predetermined time to delay the engagement of the first friction element to thereby prevent the shock from the shift.

Abstract: In a replacement gear shift effected by engagement of a first friction engagement element by increasing a first fluid pressure and instead by disengagement of a second friction engagement element by decreasing a second fluid pressure, a shift control apparatus forcibly increases the first fluid pressure at a gradual rate to prevent an undesired shift shock if the inertia phase does not end within a predetermined time.

Abstract: If, in a gear shift from one-way clutch involved gear speed to another gear speed, the inertia phase control time) is less than a predetermined time length, or the effective gear ratio on the inertia phase end detection instant is out of a range between before-shift gear ratio and after-shift gear ratio, a transmission control system controls the operating fluid pressure in a time management mode to prevent a shift shock by increasing the fluid pressure) at a gradual rate &Dgr;PC1 during a longer time interval TMC1 after an end of the inertia phase.

Abstract: An automatic transmission is driven by an engine through a torque converter. The transmission includes a plurality of friction elements which are selectively engaged to provide a selected gear thereby to transmit the power of engine to an output shaft of the transmission while changing the rotation speed. A speed change completion degree estimating system is provided, which comprises a first section that derives a difference (Nt−Ne) between an input rotation speed (Nt) of the transmission and an engine rotation speed (Ne); a second section that derives a difference (g×No−Ne) between the input rotation speed (g×No) of the transmission provided after completion of the speed change operation and the engine rotation speed (Ne); and a third section that calculates a speed change completion degree (Shift) of the transmission by using a ratio between the (Nt−Ne) and the (g×No−Ne).

Abstract: A shift control system of an automatic transmission executes an interchange shift by interchanging engagement conditions of first and second friction elements of the automatic transmission. The first and second friction elements are engaged and disengaged according to oil pressures supplied thereto. A controller of the shift control system is arranged to decrease the second oil pressure of the second friction element by a second predetermined gradient and to increase the first oil pressure of the first friction element by a first predetermined gradient after the loss stroke of the first friction element is terminated, and to determine the first gradient such that a difference between a command pressure and an actual pressure of the first friction element is kept substantially constant.