Abstract: Provided is an automatic transmission capable of smoothly switching a switching mechanism. A control part ECU of a transmission recognizes an input torque and a friction torque when an instruction to switch a two-way clutch from a fixed state to a reverse rotation prevention state is received while a first clutch, a second clutch and a third clutch are in an open state, and switches the two-way clutch from the fixed state to the reverse rotation prevention state when the input torque is equal to or greater than the friction torque.

Abstract: A power transmission apparatus for a vehicle includes a first input shaft selectively connected with an engine output shaft through a first clutch; a second input shaft selectively connected to the engine output shaft through a second clutch; a third input shaft selectively connected to the engine output shaft through a third clutch; a power transmission shaft disposed about the external circumference of the second input shaft; first and second center shafts selectively connected with each other through a fourth clutch; an idle shaft disposed in parallel with the first input shaft; a fixed transmission for selectively shifting torque input to various shafts and outputting the torque through the second center shaft and the power transmission shaft; a composite transmission configured to complementarily composite shift and output input torque; and an output shaft outputting the torque transmitted from the composite transmission to a final reduction gear.

Abstract: A fluid supply system may include a component and a bypass valve including a valve body arranged in a control channel. The valve body may be adjustable at least between a first position and a second position, the valve body cutting off a fluid channel to the component when in the first position and cutting off a bypass channel bypassing the component when in the second position. The valve body may divide the control channel into a first chamber and a second chamber. The valve body may include a leakage opening connecting the first chamber and the second chamber. The system may also include at least one detection device configured to detect a property of a fluid and transmit the detected property to a control device. The control device may be configured to close a switchable valve arranged in the leakage channel when the detected property reaches a predefined condition.

Abstract: A planet gear for use in an air turbine starter is formed of a first part having a set of gear teeth at a first axial location. A shaft extends axially away from the first set of gear teeth. A second part is interference fit on the first part, with the second part having a second set of gear teeth. The second part is mounted on the shaft of the first part. An outer diameter of the shaft is selected to be significantly larger than an inner diameter of a cylindrical portion of the second part which is interference fit on the shaft. A ratio of the outer diameter to the inner diameter is between 1.0005 and 1.0100. A planetary gear system, an air turbine starter and a method of installing a planet gear are also disclosed.

Abstract: A system includes a sump, a pump having a steady-state speed, a fluid component that receives the fluid from the fluid pump, and a controller. The controller detects a soak condition of the system in which the pump load is low as fluid is moved into vacated fluid passages. The steady-state speed of the pump is temporarily increased by adding a calibrated overspeed value to the steady-state speed, for a calibrated duration. The controller reduces the pump speed to the steady-state speed after the calibrated duration has elapsed. A method includes detecting the soak condition and temporarily increasing the steady-state speed via the controller by adding the calibrated overspeed value to the steady-state speed, for a calibrated duration, when the soak condition is detected. A control system includes a processor and storage medium having instructions embodying the method, with detection of the soak condition provided via measurement of fluid temperature.

Abstract: A vehicle has an internal combustion engine, an automatic transmission with an electrohydraulic transmission control unit, a transmission oil pump driven by the engine, and an electronic engine start and stop system. The start and stop systems switches off the internal combustion engine in operating phases, in which the vehicle is temporarily stopped, if predefined operating parameters are present, and starts the internal combustion engine if a restart signal is present. A purely mechanical pressure accumulator device provides stored hydraulic pressure to the electrohydraulic transmission control unit in a time period following the starting of the internal combustion engine, in which time period, the transmission oil pump is still building-up pressure.

Abstract: A hydraulic control system for actuating at least one torque transmitting device in a transmission includes a sump, a pump in communication with the sump, and an accumulator. A first control device and a second control device control the communication of hydraulic fluid between the pump, the accumulator, and the torque transmitting device.

Abstract: A hydraulic control system for controlling a transmission includes an accumulator, a plurality of control devices, and a plurality of valves. The accumulator provides pressurized hydraulic fluid to a pressure control subsystem during an engine restart. The plurality of control devices includes solenoids and one way ball check valves. The plurality of valves include compensator feed valves, relay valves, and mode valves.

Abstract: A method of operating a double clutch that is actuated by a hydrostatic actuating system having two clutch actuators assigned to two individual clutches and each clutch actuator including a pressure sensor for sensing the operating pressure of the respective clutch actuator, the method having the step of limiting a total actuating force of the double clutch in the event of a fault using the pressure values sensed by the pressure sensors.

Abstract: A method and system provides a Brake Transmission Shift Interlock Override mode in a vehicle including a shift-by-wire transmission. With power applied and ignition on, a driver will press and hold an override switch for a calibrated time. While the override switch is pressed, the driver presses a non-Park button for another calibrated time. The result will be that the vehicle is placed in the selected range wherein the transmission will not automatically shift to Park upon detecting a triggering event. The driver is able to shift the vehicle from Park, even if an electrical failure prevents the transmission from shifting out of Park. As such the vehicle can be driven until the failure is serviced.

Abstract: A vehicle includes one or more electric traction motors, an engine, a damper bypass clutch (DBC) assembly, a transmission, a fluid pump, a multiplexed fluid control circuit, and a controller. Two clutches and the DBC assembly are selectively engaged to select between eight transmission operating states. The DBC assembly selectively connects the engine to the transmission. The pump circulates fluid for cooling the motor(s) and actuating the clutches. The circuit has a variable force solenoid (VFS) and only three on/off solenoid valves. The solenoids are multiplexed together to control flow to the DBC assembly and to the clutches. The VFS valve controls line pressure to the on/off solenoids. The controller transmits signals to the VFS and to the on/off solenoid valves to select between the eight different transmission operating states. The multiplexed fluid control circuit is also disclosed herein.

Abstract: Power split drive (PSD) transmissions capable of energy recovery and suitable for use in automotive applications. Each PSD transmission includes a mechanical transmission system for mechanically transmitting mechanical power between a rotatable input shaft and a rotatable output shaft, and a hydraulic transmission system containing a fluid for hydraulically transmitting hydraulic power between the input shaft and the output shaft, and at least a third shaft operatively interconnected to one of the mechanical and hydraulic transmission systems. The hydraulic transmission system is operatively coupled by at least a first planetary gear train to the mechanical transmission system. According to the invention, the PSD further comprises means operatively associated with at least one of the mechanical and hydraulic transmission systems for storing and releasing energy within the PSD transmission, the energy storing and releasing means comprising a flywheel or an accumulator or a combination thereof.

Abstract: A hydraulic control system for actuating at least one torque transmitting device in a transmission includes a sump, a pump in communication with the sump, and an accumulator. A first control device and a second control device control the communication of hydraulic fluid between the pump, the accumulator, and the torque transmitting device.

Abstract: A vehicle drive unit includes a clutch pressure control valve that controls hydraulic pressure for operating the clutch; a clutch control valve that is provided in a first oil passage between the clutch pressure control valve and the clutch, and that controls hydraulic pressure in an engagement state between full engagement and disengagement of the clutch; a second oil passage that bypasses the clutch control valve and that is arranged parallel to the first oil passage; and a shift valve that connects, to an oil passage connected to the clutch, the first oil passage when controlling the engagement state between full engagement and disengagement of the clutch, and the second oil passage when not controlling the engagement state between full engagement and disengagement of the clutch.

Abstract: The adjustment method includes an estimation step in which valve characteristics of the linear solenoid valves fitted to the hydraulic control circuit are measured, and estimated linear valve characteristics of the linear solenoid valves in isolation state are estimated based on the measured valve characteristics using predetermined correlations; and a correction value output step in which estimated linear piston-end pressures of the hydraulically-driven friction engagement elements immediately before the hydraulically-driven friction engagement elements are engaged are calculated based on the estimated linear valve characteristics, and the correction values that are applied to the control command values to adjust the drive currents supplied from the valve control unit to the linear solenoid valves are calculated based on differences between the estimated linear piston-end pressures and nominal piston-end pressures, and then output.

Abstract: A control unit for an electric oil pump of the present invention includes: a one-way valve that permits circulation of operating fluid from the electric oil pump to the friction engagement device and blocks circulation in the opposite direction; an accumulator that is connected to a fluid supply path joining the one-way valve to the friction engagement device and accumulates hydraulic pressure required for operating the friction engagement device; a hydraulic pressure measuring device that measures hydraulic pressure inside the fluid supply path; a vehicle speed measuring device that measures a vehicle speed of the vehicle; and a pressure setting device that sets a first predetermined pressure based on the vehicle speed measured by the vehicle speed measuring device.

Abstract: A modified automatic transmission includes a simple and inexpensive accumulator orifice plate residing between a valve control body and a second gear accumulator. The accumulator is in parallel fluid communication with a second gear servo and moderates changes to pressure of transmission fluid flowing to the second gear servo to reduce or eliminate harsh shifting. The accumulator is also in fluid communication with an Electronic Pressure Control (EPC) accumulator valve which provides an opposing transmission fluid flow into the accumulator to provide faster or firmer shifting when desired. The accumulator orifice plate includes orifices aligned with passages carrying the transmission fluid flows into the accumulator thereby restricting the flows. The orifices have specific sizes to limit the transmission fluid flows into the accumulator and thereby customize the shifting characteristics to suit an individual driver's preferences and/or needs and stabilizing pressure changes due to the EPC accumulator valve.

Abstract: An automatic transmission damper mechanism provided between a first hydraulic passage (23) to which an oil (L) is supplied and a second hydraulic passage (24) from which the oil (L) is supplied to a friction element (18) has: a container (8) provided between the first and second hydraulic passages (23, 24); a slide member (11) provided in the container (8) such that it can slide therein; and an elastic member (9) provided between an inner face of the container (8) and the slide member (11). The container (8) has a pressure chamber (28) defined by an inner face of the container (8) and the slide member (11) and communicating with a branch hydraulic passage (25) branching from the first hydraulic passage (23), and the slide member (11) has a communication hole (15) through which the first and second hydraulic passages (23, 24) are placed in communication by the elastic member (9) contracting under the pressure of the oil (L) supplied into the pressure chamber (28) through the branch hydraulic passage (25).

Abstract: An electro-hydraulic control system for a transmission is provided having first, second, and third selectively engageable torque transmitting mechanisms. The control system includes a main source of fluid pressure and first, second, and third trim valves operable to effect the engagement of respective first, second, and third torque transmitting mechanisms. A latch valve is in fluid communication with the first torque transmitting mechanism and an interlock valve is in selective fluid communication with the latch valve. The first trim valve, latch valve, and interlock valve are in fluid communication with the main source of fluid pressure. The first trim valve operates selectively communicate fluid pressure to the latch valve to effect engagement of the first torque transmitting mechanism, while the interlock valve is operable to selectively communicate fluid pressure to one of the second and third trim valve to effect engagement of the respective second and third torque transmitting mechanisms.

Abstract: A drive train for a motor vehicle includes a coupling device between a drive unit and a transmission for torque or moment transfer between the drive unit and the transmission. The coupling device has at least one coupling arrangement that can be activated by a pressure medium. The transmission can be activated through the use of a pressure medium by way of a dedicated actuator whereby, on the basis of a shared pump arrangement that is or can be driven by the drive unit, (i) the pressure medium can be provided for activation of the coupling arrangement, (ii) the operating medium can be conducted to the coupling device for the purpose of operating under the influence of the operating medium, and (iii) the pressure medium can be provided for activation of the transmission. The pump arrangement includes at least one pump, which can be controlled or adjusted with regard to output pressure and/or with regard to output flow rate.

Abstract: A shift control apparatus for controlling shifting actions of an automatic transmission including a hydraulically operated frictional coupling device having a hydraulic cylinder which is supplied with a working fluid when the frictional coupling device is engaged, the shift control apparatus including a transient-hydraulic-pressure control device operable to control a transient value of a hydraulic pressure in the hydraulic cylinder according to an electric signal, upon releasing of the frictional coupling device, and an accumulator having a back-pressure chamber a back pressure of which is controllable, and an accumulator chamber connected to the hydraulic cylinder of the frictional coupling device and operable to control a transient value of the hydraulic pressure in the hydraulic cylinder, when the frictional coupling device is engaged with the working fluid being supplied to the hydraulic cylinder, and a back-pressure increasing portion operable to increase the back pressure in the back-pressure chamber o

Abstract: A shift control apparatus for controlling shifting actions of an automatic transmission including a hydraulically operated frictional coupling device having a hydraulic cylinder which is supplied with a working fluid when the frictional coupling device is engaged, the shift control apparatus including a transient-hydraulic-pressure control device operable to control a transient value of a hydraulic pressure in the hydraulic cylinder according to an electric signal, upon releasing of the frictional coupling device, and an accumulator having a back-pressure chamber a back pressure of which is controllable, and an accumulator chamber connected to the hydraulic cylinder of the frictional coupling device and operable to control a transient value of the hydraulic pressure in the hydraulic cylinder, when the frictional coupling device is engaged with the working fluid being supplied to the hydraulic cylinder, and a back-pressure increasing portion operable to increase the back pressure in the back-pressure chamber o

Abstract: Methods and systems for improving the operation of transmissions for automotive vehicles increase the main line fluid pressure of a “factory installed” transmission to permit shifting of gears at proper time intervals without undesireable side effects including late or delayed shifts. The hydraulic circuitry of a “factory installed” automotive transmission is also modified to increase the accumulator range to improve the quality of a “1-2” shift, and to extend the useful operating life of the transmission. A seal assembly is provided for reducing leakage of transmission fluid, and additional modifications to the hydraulic circuitry of the automotive transmission provide a smooth, quick and positive forward clutch apply circuit, and increase the servo-apply pressure to the intermediate and overdrive servos to increase the holding capacity of the second and fourth bands and to adjust the field of the shift.

Abstract: Disclosed is a forward/reverse control system for a continuously variable transmission comprising pressure regulating means for controlling an inputted line pressure according to whether a forward or reverse state is required; a manual valve for selectively supplying and exhausting hydraulic pressure, which is supplied from the pressure regulating means, to and from a forward clutch and a reverse brake; and a check ball unit mounted between a forward hydraulic line and a reverse hydraulic line, which are connected respectively to the forward clutch and the reverse brake, the check ball unit operating to communicate the forward hydraulic line with an accumulator when hydraulic pressure acts on the forward clutch and operating to communicate the reverse hydraulic line with the accumulator when hydraulic pressure acts on the reverse brake.

Abstract: Methods and systems for improving the operation of transmissions for automotive vehicles increase the main line fluid pressure of a “factory installed” transmission to permit shifting of gears at proper time intervals without undesireable side effects including late or delayed shifts. The hydraulic circuitry of a “factory installed” automotive transmission is also modified to increase the accumulator range to improve the quality of a “1-2” shift, and to extend the useful operating life of the transmission. A seal assembly is provided for reducing leakage of transmission fluid, and additional modifications to the hydraulic circuitry of the automotive transmission provide a smooth, quick and positive forward clutch apply circuit, and increase the servo-apply pressure to the intermediate and overdrive servos to increase the holding capacity of the second and fourth bands and to adjust the field of the shift.

Abstract: An apparatus for controlling a vehicle automatic transmission having a hydraulically operated frictional coupling device operable to effect a shifting action of the automatic transmission, and an accumulator connected to the frictional coupling device, the apparatus including an accumulator-back-pressure learning compensation device operable to effect learning compensation of a back pressure of the accumulator such that an actual value of a rate of change of a rotating speed of a selected rotary element of the automatic transmission, which rotating speed changes as a result of the shifting action, approaches a predetermined target value, and an accumulator-back-pressure control device operable to control the back pressure, on the basis of an output of the accumulator-back-pressure leaning compensation device, whereby a shifting shock of the transmission can be reduced.

Abstract: A method of determining shift points in a step gear transmission system to maximize fuel economy is disclosed. In operation, the method uses fuel economy data from a first gear ratio to determine a first series of constant fuel consumption curves for the first gear ratio. The method then uses fuel economy data from a second gear ratio to determine a second series of constant fuel consumption curves for the second gear ratio. Next, the method determines points of intersection where a respective fuel consumption curve for the first gear ratio intersects its corresponding fuel consumption curve for the second gear ratio. A decision curve is generated from the points of intersection.

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: An accumulator of a transmission, and method of modifying an accumulator, includes a replacement spring. The replacement spring replaces the typical shorter spring of shorter and longer springs biasing a valve in a cylinder of an accumulator valve body. The replacement spring has a length greater than the replaced short spring, but less than or equal to the longer spring. The replacement spring provides a shorter shift duration and a firmer shift.

Abstract: A hydraulic control system for an automatic transmission includes first and second passages connected to first and second engaging elements, first and second accumulators arranged with the first and second passages, and a timing valve connected to a back-pressure chamber of the first accumulator and for determining a timing for draining a first pressure within the back-pressure chamber of the first accumulator in accordance with a second pressure within a back-pressure chamber of the second accumulator.

Abstract: A neutral control device of an automatic transmission is provided which includes a forward-drive engaging element that is engaged when a hydraulic pressure is supplied from a shift valve, so as to place the transmission in at least a 1st-speed gear position of a forward-drive range, and in which the pressure to the forward-drive engaging element is controlled so as to establish a neutral condition by slipping and engaging the forward-drive engaging element, while an accelerator pedal is being released just before the start or stopping of the vehicle.

Abstract: In apparatus and method for controlling a gear shift of a vehicular automatic transmission, the automatic transmission the automatic transmission having a releasing frictional element, a clutching frictional element, and a source of a releasing working liquid pressure to be applied to the releasing frictional element and a clutching working liquid pressure to be applied to the clutching frictional element, a gear shift in the automatic transmission being carried out by a shift from the releasing frictional element to the clutching frictional element, during a time duration from a time at which a gear shift instruction is outputted to a time at which a torque phase is started, the releasing working liquid pressure is reduced and reached without undershooting to a first predetermined working liquid pressure value under which the releasing frictional element is in a state immediately before an occurrence of a slip and the clutching working liquid pressure is set at least a second predetermined working liquid pre

Abstract: An upshift is effected by releasing an engaged first friction element and engaging a released second friction element. The first fiction element operates on a fluid pressure applied thereto through a first passage and the second friction element operates on a fluid pressure applied thereto through a second passage. An accumulator is provided in the first fluid passage. The accumulator has a back pressure port through which a back pressure is applied thereto by the function of a control valve having a first port connected to the back pressure port, a second port connected to a source of back pressure and a third port connected to a drain. The control valve operates, between a first position connecting the first port to second port and a second position connecting the first port to the third port, on first and second working signal pressures applied thereto.

Abstract: A hydraulic control system for an automatic transmission used in a vehicle, the hydraulic control system includes a pressure regulating part for regulating hydraulic pressure generated from a hydraulic pump to constant line pressure, a manual valve selectively supplying hydraulic pressure to a drive pressure passage, a reverse pressure passage, and a first and a second speed pressure passage. A pressure control part supplies standard pressure to solenoid valves which are duty-controlled by a transmission control unit. The pressure control part has a solenoid supply valve. A damper clutch control part controls a damper clutch of a torque converter. A pressure distributing part distributes an appropriate amount of pressure to friction members, and has shift valves and clutch valves. A torque pressure generating part reduces the line pressure so that it can be used for initial shifting control.

Abstract: An upshift control device for an automatic transmission is provided in which the transmission is shifted up by releasing an oil pressure from a first engaging element that has been engaged while applying an oil pressure to a second engaging element that has been released. This upshift control device includes engine racing detecting means for detecting racing of an engine of the vehicle during upshifting, and engine racing preventive control mans for generating to an actuator of a timing valve a command to temporarily apply a pressure to a back pressure chamber of a first accumulator which is provided in an oil path leading to the first engaging element and from which the pressure has been released, when racing of the engine is detected after the upshift command is generated.

Abstract: A hydraulic control system of an automatic transmission. A pressure regulator valve of the hydraulic control system includes a pressure reducing valve for reducing oil pressure created in an oil pump to a predetermined level; a duty solenoid valve for creating a solenoid pressure by draining the oil reduced in the pressure reducing valve according to duty level of a transmission control unit based on open level of a throttle valve; and a pressure regulator valve for supplying the controlled oil to a manual valve acting in relation to a shift lever by controlling pressure of the oil supplied directly from the oil pump based on the reduction of the fluctuation in shock in the pressure accumulating valve.

Abstract: The invention relates to a power-shiftable two-speed gear. The gear is designed as planet gear (3). The two ratios can be hydraulically shifted via two friction clutches (9 and 10). At least one of the friction clutches (9 or 10) is fitted with a mechanism which prevents the full locking pressure from acting upon the friction components during downshifts or upshifts. A store (30), which the torque curve can be affected, is used for this purpose. To prevent traction loss and abrupt changes which are found to be particularly unpleasant, the store (30) consists of a cylinder (32) and a piston (33) is fitted in the line (18 and 24) leading to the pressure chamber (17 and 23). A non-return valve (28) with a choke (29) in parallel with it is integrated into the piston.

Abstract: A shift control apparatus for an automatic transmission includes a first transmission gear unit equipped with a clutch to clutch shift mechanism and a second transmission gear unit which is operatively connected in series with the first transmission gear unit and which is equipped with a clutch to one-way clutch shift mechanism. A clutch controller controls the clutch-to-clutch shift mechanism and the clutch to one-way clutch shift mechanism in such a manner that rotational synchronization of the clutch to one-way clutch shift mechanism is caused to take place earlier than or at the same time as rotational synchronization of the clutch to clutch shift mechanism when gear shifting is effected over the first and second transmission gear units.

Abstract: In a hydraulic control device for an automatic transmission for obtaining the optimum shift-down timing by regulating an accumulator back pressure for an engaging element to be engaged in low-speed gear positions, switch control means is provided for communicating an output oil path communicating with an accumulator back pressure chamber, with a selected one of an accumulator control pressure oil path and a drain oil path. The switch control means maintains communication between the output oil path and the accumulator control pressure oil path due to the output feed-back pressure in the N-speed gear position, and brings the output oil path into communication with the drain oil path, using the N+1 pressure as the operating signal pressure, upon shifting-up from the N-speed to N+1-speed gear position.

Abstract: A hydraulic control system of a vehicle automatic transmission includes a torque converter, an oil pump, a pressure regulator, a damper clutch working control means, a manual valve, an N-D control valve, a torque control regulator valve, a control switch valve, a first to second, second to third, third to fourth, and third to second shift valves, a low/reverse clutch valve, a third clutch valve, and a second to fourth brake valve.

Abstract: A control system for an automatic transmission having at least a friction coupling element which is coupled with a hydraulic pressure increasing by way of a leveled transitional pressure has an accumulator which discharge a high level of pressure accumulated therein into the fiction coupling element during a gear shift under the condition where the line pressure is low.

Abstract: A hydraulic control system of an automatic transmission, which includes a line pressure regulator for regulating the hydraulic pressure supplied from an oil pump to the hydraulic control line, and a shift structure for selectively delivering the regulated hydraulic pressure to the friction elements, wherein the shift structure further comprises a manual valve operatively linked with a shift lever for delivering the regulated hydraulic pressure according to shift ranges, a plurality of solenoid valves controlled on/off by a transmission control unit to control the friction elements, a first to a fifth pressure control valves for simultaneously controlling both releasing and connecting end of the friction elements, a first-to-second shift valve for making a port change by the hydraulic pressure flowing out from the pressure control valves to deliver the pressure to the friction elements, a forward drive clutch release valve, a second-to-third shift valve, and a reverse drive clutch valve.

Abstract: An automatic transmission control system has first and second hydraulic circuits leading to a low/reverse brake and a reverse clutch, respectively, which perform supplying and discharging of hydraulic pressure to the low/reverse brake and reverse clutch, respectively, so as to lock and unlock them. The first circuit is provided, from the upstream end, with an orifice for restraining hydraulic pressure, an accumulator disposed downstream from the orifice for pressure accumulation, and a switching valve for switching supply and discharge of the hydraulic pressure. The second hydraulic circuit is provided, from the upstream end, with a switching valve for switching communication of the first hydraulic circuit between the orifice and switching valve with the second hydraulic circuit and communication of the first hydraulic circuit upstream from the orifice with the second hydraulic circuit.

Abstract: A pressure control apparatus which controls a hydraulic pressure to be supplied to a hydraulic servo system of an automatic transmission. The pressure control valve includes a shift control valve for controlling the hydraulic pressure to be supplied to the servo system upon receiving the feedback from the servo system and an accumulator disposed between the pressure control valve and the servo system through an orifice. The feedback portions of the pressure control valve have the same area with each other. Therefore, a build-up time of the hydraulic pressure to the servo system is kept constant without being effected by a line pressure and a back pressure of the accumulator.

Abstract: A diagnosing apparatus for diagnosing a vehicle automatic transmission system including an automatic transmission having frictional coupling devices, and solenoid-operated valves for controlling the frictional coupling devices to shift the automatic transmission according to shift commands generated by a control device, the apparatus including a speed detector for detecting an engine speed of the vehicle, a device for determining a reference range of the engine speed within which the engine speed is expected to fall when the transmission is placed in a position selected by a shift command, a device for determining whether a predetermined running condition of the vehicle is satisfied, and a defect detector for determining whether there exists a defect associated with the automatic transmission system, depending upon whether the detected engine speed is held within or outside the determined reference range when the predetermined vehicle running condition is satisfied.

Abstract: The invention relates to hydraulically engaged by means of two friction clutches (9 and 10). For that purpose, friction elements (outer and inner disks 13, 14 and 19, 20) are alternatively engaged and disengaged by the force exerted by plate springs (16, 22) or by hydraulic fluid. A mechanism associated with one of the friction clutches (9 or 10) prevents the full force of the spring from acting on the friction elements when the gear is shifted down from a higher to a lower step. An accumulator (30) is preferably used to influence the torque transmission during a downshift. An essential advantage of the disengaged arrangement consists in the smoothness of the shifting operation during downshifts, avoiding a particularly disagreeable hard shifting which is otherwise felt.

Abstract: A hydraulic control unit for an automatic transmission having a plurality of power transmitting paths and a plurality of engaging clutches and/or brakes for selecting any one of the transmitting paths to set a gear position. The unit comprises a regulator valve for producing a line pressure, an operating pressure control valve for producing an operating pressure supplied to the engaging clutch or brake by regulating the line pressure from the regulator valve, and a line pressure switching valve for making the line pressure produced by the regulator valve low at a specified gear position when a target operating pressure set by the operating pressure control valve is lower than a specified value and making the line pressure high when the target operating pressure is higher than the specified value.

Abstract: A controller of an automatic transmission provides gear changes with optimum gear change characteristics under any traveling conditions. The controller of the automatic transmission of the present invention includes an input torque detector for determining input torque to the transmission, an inertia torque estimator for estimating an inertia torque corresponding to the rate of change of rotary speed of a rotary member during a gear change, input torque corrector for calculating a required operating torque by adding the input torque and the inertia torque and an operating pressure controller for controlling operating pressure to correspond to the required operating torque. The operating pressure corresponding to the necessary engagement torque is supplied to a hydraulic servo, to effect a gear change, irrespective throttle opening and driving speed and irrespective of whether the gear change is made step by step or jumped.

Abstract: An automatic power transmission of an automotive vehicle includes various frictional elements and frictional brakes and can prevent a shift shock from occurring by increasing a working hydraulic pressure applied to a certain frictional element (forward clutch F/C) so as to make fast a reengagement of the certain frictional element when a down-shifting from a high gear speed range to a low gear speed range occurs. In a preferred embodiment, the working hydraulic pressure present during the down-shifting is introduced into an accumulator so as to disable a stroke of the accumulator. In another preferred embodiment, a time at which a shifting solenoid (A) is turned from its ON state to its OFF state is retarded after a control valve control solenoid (C) is turned from its OFF state to its ON state in response to an instruction of a controller to shift down the gear speed range. In addition, a fuel consumption of the associated engine is improved by an extension of a lock-up interval off a torque converter.

Abstract: An automotive automatic transmission has a hydraulically operated clutch device and an electronic control unit. The clutch device includes drive and driven clutch plates and a piston for pressing the drive and driven clutch plates to establish an engagement therebetween when an oil chamber for the piston is fed with a certain amount of fluid. In order to control the clutch device, the following steps are employed, which are (a) issuing a first instruction signal to the clutch device; (b) feeding the oil chamber with the fluid by an amount which is sufficient for moving the piston from a rest position to a critical position which is ready for effecting the actual pressure against the drive and driven clutch plates; (c) issuing a second instruction signal to the clutch device; and (d) increasing the hydraulic pressure in the oil chamber to cause the piston to instantly establish the engagement between the drive and driven clutch plates.