Abstract: Each control portion for controlling each friction element includes a switch valve and pressure control valve such that hydraulic pressure supplied to the friction element is fully controlled, and a control portion for controlling a friction element that is operated both at low and high speeds includes a switch valve that senses an operation of a friction member cooperatively with the friction element at the high speed such that the friction member receives different hydraulic pressure at low and high speeds. A plurality of fail-safe valves is included for enhancement of a fail-safe function of an automatic transmission.

Abstract: The present invention is directed to methods and systems for improving the operation of transmissions for automotive vehicles, and in particular the “factory installed” automotive transmissions installed by the original automobile manufacturer. The methods and systems in accordance with the present invention modify both the structural components and the hydraulic circuitry of the original automotive transmissions to enhance the operation of the modified transmissions. The improvements to the operation of the “factory installed” transmissions, and in particular the Allison transmission, include modification of the flow control valve to increase line pressure during lockup; modifications to the rotating clutch module to increase the torque held by the clutch and prevent clutch slippage, and modifications to the trim valves to adjust the pressure applied to the clutches for more efficient operation of the transmission.

Abstract: The oil supply device for a change-under-load transmission having a high-pressure circuit and a low-pressure circuit is designed in such a manner that the high-pressure feed line to the consumer devices of the transmission system incorporates an inlet aperture of small size, the low-pressure feed line is connected between the inlet aperture and the consumer device, and the low-pressure feed line can be cut off from the high-pressure feed line by a one-way valve.

Abstract: A transmission line pressure controller compensates for pump speed effect on transmission line pressure. A sensor determines a pressure of a pressure control actuator. The controller determines a selected transmission range, including drive or reverse. The controller determines an effective engine speed. The controller adjusts the pressure control actuator according to the selected transmission range and the effective engine speed.

Abstract: A judging section judges whether or not ranges detected, respectively, by a first range detection section consisting of a first detection section and a position detecting sensor, and a second range detection section consisting of a second detection section; a C1 detecting sensor and a B1 detecting sensor are in mutual agreement, and when the detected ranges are not in mutual agreement, a failure judging section judges a failure of the first range detection section.

Abstract: An ECT-ECU includes an abrupt turbine speed increase learning control circuit which prevents simultaneous release of both a frictional engagement element to be released and a frictional engagement element to be engaged, a tie-up learning control circuit which prevents simultaneous engagement of both the frictional engagement element to be released and the frictional engagement element to be engaged, a determination circuit that determines whether one of tie-up learning control and abrupt turbine speed increase learning control is necessary based on the turbine speed, and a control circuit that prohibits execution of the tie-up learning control unless the number of trips after the abrupt turbine speed increase learning control has been executed is at least equal to a predetermined number, when it has been determined that the tie-up learning control is necessary.

Abstract: There is provided a hydraulic control device for an automatic transmission, which is comprised of an engagement state determining section and a protection control section. If the engagement state determining section determines that each clutch, which is supplied with a line pressure via a regulating valve having a spool and has an oil pressure switch disposed in an oil channel, is held in an engaged state when gears are not changed, the protection control section sets a command pressure for the regulating valve to a protective oil pressure lower than the line pressure. This brings the regulating valve into a pressure-regulating state to cause lands of the spool to form apertures that reduce hydraulic vibration applied to the line pressure. This inhibits an oil pressure beyond an acceptable value from being applied to the oil pressure switch, and therefore improves the durability of the oil pressure switch.

Abstract: An engagement force for engaging a first friction engagement element is set to be lower than an engagement force for establishing a predetermined shift stage with a second friction engagement element being engaged when a vehicle is stopped with an acceleration pedal not being operated and a brake pedal being operated under a forward driving range in an automatic transmission. The engagement force for the first friction engagement element is increased when a vehicle starts with the brake pedal released from the operated condition, and the engagement force for engaging the second friction engagement element is decreased when a relative rotational speed between a turbine wheel and a forward movement member becomes equal to or smaller than a predetermined rotational speed.

Abstract: The powertrain of a six-speed powertrain and a hydraulic control system includes a main shift section of first and second single pinion planetary gearsets, in which a first planet carrier is fixedly connected to a second ring gear. The powertrain also includes a first ring gear fixedly connected to a second planet carrier, and a first sun gear. The second planet carrier, and a second sun gear are variably connected to an input shaft through first, second, and third clutches, respectively. A connecting member connecting the first ring gear and the second planet carrier is variably connected to a housing through a first brake and a first one-way clutch. The second sun gear being variably connected to the housing by a second brake.

Abstract: An oil pressure control device has bypass drain oil passages that bypass a control valve and that are capable of draining the engaging pressure K from a hydraulic servo of a clutch when releasing the clutch. A drain-prohibiting check ball blocks a drain path between a manual valve and an input port.

Abstract: A pressure regulator valve assembly for an automatic transmission that provides continuous hydraulic fluid flow into the torque converter charge circuit in all operating modes to prevent torque converter overheating is disclosed. The present pressure regulator valve assembly includes a valve piston subassembly having an encapsulated internal check valve in fluid communication with the line pressure circuit, which diverts hydraulic fluid to the torque converter charge circuit responsive to a lower fluid pressure (i.e. 2-5 psi range) than is normally required to fill the torque converter. When the vehicle engine is shut off, the internal check valve also prevents hydraulic fluid from draining back through the pressure regulator valve to maintain an adequate fluid level in the torque converter. In addition, an internal balance boost circuit has been added to the valve piston subassembly to assist the balance circuit in counteracting electronic pressure control (EPC) solenoid pressure.

Abstract: An automatic transmission is comprised of a housing and a hub rotatable about a shaft at differing speeds and having an axial assembly gap therebetween. The axial assembly gap defines an annular flow path in fluid communication with a source lubrication path and a lubrication-requiring mechanism. A lubrication control device is disposed in the annular flow path. The device includes a washer in constant contact with the housing and having a radial slot to permit a prescribed flow of lubricant through the annular flow path to the lubrication-requiring mechanism. The device further includes a belleville spring wherein a small diameter end is in contact with the hub and a large diameter end is piloted by a seating on the washer, wherein the belleville spring provides spring adjustability to accommodate the variable axial assembly gap.

Abstract: To prevent the neutral state from being formed in a change gear apparatus and allow the obtaining of an intended gear change appropriately during a servo malfunction. Hydraulic servos engage and disengage a plurality of friction engagement elements; a hydraulic pressure supply system supplies the hydraulic servo of a predetermined friction engagement element with hydraulic pressure; and an auxiliary hydraulic pressure supply systems supplies a predetermined hydraulic servo with another hydraulic pressure, in the case where the hydraulic pressure supply system is placed in a first unsupplied state where the hydraulic pressure supply system cannot supply the hydraulic servo of the predetermined friction engagement element with hydraulic pressure.

Abstract: A self-regulating reverse boost valve assembly for installation within the hydraulic pump of an automatic transmission is disclosed. The present reverse boost valve assembly operates in conjunction with the pressure regulator valve to control line pressure generated by the hydraulic pump boosting line pressure in relation to engine torque. The present reverse boost valve assembly includes an internal check valve mechanism that is actuated whenever torque signal fluid pressure (proportional to engine torque) exceeds a predetermined level. When the internal check valve mechanism is actuated, the excess torque signal fluid pressure is diverted via an internal exhaust channel to the transmission sump. Thus, any drastic rise in main line hydraulic pressure or high line pressure in reverse gear, which can result in broken direct clutch drums and/or broken transmission cases, is prevented.

Abstract: A microvalve device for controlling fluid flow in a fluid circuit. The microvalve device comprises a body having a cavity formed therein. An electronically controlled automatic transmission, comprising of an input shaft; an output shaft; a plurality of gears providing driving connection between the input shaft and the output shaft; one of a hydraulically operated brake band and a hydraulically operated clutch which is operable to effect a change in the gear reduction provided by the gears between the input shaft and the output shaft; a source of pressurized hydraulic fluid; and a microvalve device selectively operable to control passage of pressurized hydraulic fluid from the source to the one of a hydraulically operated brake band and a hydraulically operated clutch to operate the one of a hydraulically operated brake band and a hydraulically operated clutch.

Abstract: A hydraulic control system for an automatic transmission, in which four forward speeds and one reverse speed are realized by the use of a reduced number of friction elements compared to the prior art such that overall structure is simplified, the weight of the automatic transmission is decreased, and the cost of production is reduced. In the hydraulic control system, hydraulic pressure generated in an oil pump is controlled to a predetermined level by a regulator valve, and part of this pressure is supplied as operational pressure of a damper clutch and to a reducing valve, and another part of this pressure is supplied to a hydraulic pressure control section for the selective supply of operational pressure to friction elements that are engaged in each shift range and speed, the hydraulic pressure control section including a shift control assembly, a hydraulic pressure control assembly, a switching assembly, a fail-safe assembly, and a N-R control assembly.

Abstract: When an SLT pressure of a linear solenoid valve is input into a control oil chamber of a garage shift control valve, and a direct control pressure from the garage shift control valve is output to a clutch or a brake, a hydraulic controller inputs the direct control pressure into a control oil chamber and executes feedback-control. Also, when a range pressure of a clutch modulator valve is output to the clutch or the brake by switching the garage shift valve, the hydraulic controller inputs the range pressure, which is higher than the SLT pressure, into the control oil chamber and fixes the garage shift control valve.

Abstract: Apparatus for controlling a vehicle automatic transmission having a hydraulically operated frictional coupling device operable to effect a shifting action of the automatic transmission, a switching valve operable according to a shifting command to effect the shifting action, and a pressure regulating valve operable to control a pressure of a working fluid to be supplied to the frictional coupling device through the switching valve to effect the shifting action, the apparatus including (a) a fluid temperature detector operable to detect a temperature of the working fluid, and (b) a delaying device operable to delay a moment of initiation of an operation of the pressure regulating valve to control the pressure of the working fluid to be supplied to the frictional coupling device for effecting the shifting action, such that the moment of initiation is delayed depending upon the detected working fluid temperature, to reduce a shifting shock of the automatic transmission.

Abstract: An oil pressure control apparatus for an automatic transmission helps ensure sufficient oil pressure to be supplied to a friction engagement element for performing at least either a first shift stage or a reverse shift stage. Further, the oil pressure control apparatus for the automatic transmission effectively performs pressure adjustment of the oil pressure to be supplied to the friction engagement element upon shifting a neutral shift stage to either the first shift stage or the reverse shift stage.

Abstract: An oil pressure control device has bypass drain oil passages that bypass a control valve and that are capable of draining the engaging pressure K from a hydraulic servo of a clutch when releasing the clutch. A drain-prohibiting check ball blocks a drain path between a manual valve and an input port.

Abstract: A pressure regulating valve regulates an original pressure outputted from a manual valve by means of a control pressure generated by a solenoid in a D range and supplies the regulated original pressure to an engaging element. An electronic control unit filters a current signal supplied to the solenoid to generate the control pressure by using a strong filter when a N range is switched to a D range during stoppage of a vehicle so that the control pressure has a gentle rise characteristic, switches the filtering process to a filtering process using a weak filter to rapidly move the pressure regulating valve in a working pressure discharge direction when the N range is switched to the D range during running of the vehicle and returns the filtering process to the filtering process using a strong filter after a predetermined time period. Thereby, occurrence of shock is suppressed when the D range is again selected after the N range is selected during running in the D range.

Abstract: A hydraulic control apparatus for an automatic transmission having a plurality of transmission gear trains. The hydraulic control apparatus performs a gear shift operation by a select actuator and a shift actuator. When the shift actuator is actuated to a neutral position, an oil pressure is supplied from a shift position detection valve toward the select actuator which selects a gear shift stage switching mechanism. When the oil pressure is supplied by a normally open solenoid valve, and also a reverse gear stage switching mechanism is selected, a pilot pressure is supplied from a select position detection valve to a forcible reverse shift valve. Thus, one oil pressure supplied to the shift actuator is shut off. When the shift actuator actuates the reverse gear stage switching mechanism, the shift position detection valve is actuated so that the oil pressure from the select position detection valve is supplied to an input clutch.

Abstract: A Lube Regulated Pressure Regulator Valve including an internal check valve that passes transmission fluid from the hydraulic pump in an amount sufficient to fill the torque converter in the Park gear range and at low engine speeds is disclosed. The internal check valve opens at a substantially lower line pressure than is required to open the original equipment manufacture pressure regulator valve to ensure the torque converter is operational at engine startup. As engine speed increases and sufficient line pressure builds up within the torque converter charge circuit, the internal check valve is closed and the pressure regulator valve opens as it would normally to feed line pressure to the torque converter directly. When the engine is shut off, the internal check valve is biased to a closed position preventing automatic transmission fluid from draining back from the torque converter through the pressure regulator valve to the fluid sump.

Abstract: A device for control of a hydraulically actuatable shifting element of a motor vehicle transmission, especially of a powershift transmission, comprising one clutch piston which defines, with a first surface, a hydraulically pressurizable piston space and, with a second surface of different size, a hydraulically pressurizable reset space and comprising a slide valve system which has a first clutch valve associated with the piston space, a second clutch valve associated with the reset space and a holding valve associated with the reset space.

Abstract: The present invention is directed to methods and systems for improving the operation of transmissions for automotive vehicles, and in particular, the “factory installed” automotive transmissions installed by an original automobile manufacturer. The methods and systems modify both the structural components and hydraulic circuitry of the original automotive transmissions to adjust applied pressure and shifting patterns to enhance the operation of the modified transmissions.

Abstract: A line pressure regulating system for an automatic transmission comprises a regulator valve that regulates a line pressure by being provided with a hydraulic pressure from an oil pump, wherein the regulator valve is controlled such that a resultant force of a variable control pressure and an elastic member makes an equilibrium with a resultant force of the line pressure and a range pressure that is provided in all ranges except the R range.

Abstract: A second shift valve for a lock-up clutch is switched in response to supply of an R range pressure and a solenoid pressure from a low-and-reverse solenoid valve to selectively supply an output from a lock-up solenoid valve to a pressure reduction control valve or a lock-up control valve. The pressure reduction control valve regulates a line pressure at a small gain by the output from the lockup solenoid valve via the second shift valve. The first shift valve actuated by the solenoid pressure from the low-and-reverse solenoid valve selectively supplies a high R range pressure from a manual valve or an output from the pressure reduction control valve to the low-and-reverse brake. This enables accurate hydraulic control of the low-and-reverse brake and ensures the required torque capacity with simple arrangement.

Abstract: At the time of the 6→3 speed shift, an automatic transmission achieves a 6→4→3 speed shift by controlling the servo pressures of four engageable elements. A control apparatus controls the servo pressure of one engageable element in accordance with the servo pressures of other engageable elements. The engagement and release timings are adjusted by determining and controlling the oil pressures of the hydraulic servos, taking into consideration the 6→4 shift state (torque sharing) during a shift transitional period. Therefore, engine blow and prolongation are prevented during the 6→3 shift control.

Abstract: A shift control apparatus that advances activation of an engagement element to be engaged during a shift requiring engagement and release of four engagement elements, thereby reducing the shift time. The automatic transmission achieves a sixth-to-fourth-to-third shift by controlling servo pressures for the four engagement elements. The control apparatus starts, during the time of the sixth-to-third shift, supply of the hydraulic pressure for activating the engagement element to be engaged at the time of the fourth-to-third shift, thereby advancing the establishment of the engagement stand-by state at the time of the fourth-to-third shift. Accordingly, the reduction in the servo pressure of the engagement element to be released at the time of the fourth-to-third shift can be advanced, thereby reducing the time for the sixth-to-third shift.

Abstract: A hydraulic control system in which hydraulic pressure generated pressure generated by an oil pump is supplied to a pressure/damper clutch controller, a pressure reducer, and a shift controller, wherein the pressure reduced by the pressure reducer and the hydraulic pressure supplied as a result of port conversion of the sift controller are supplied to the hydraulic pressure controller, and hydraulic pressure controlled by the hydraulic pressure controller is supplied to a hydraulic pressure distributor and directly to some friction elements.

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: When an SLT pressure of a linear solenoid valve is input into a control oil chamber of a garage shift control valve, and a direct control pressure from the garage shift control valve is output to a clutch or a brake, a hydraulic controller inputs the direct control pressure into a control oil chamber and executes feedback-control. Also, when a range pressure of a clutch modulator valve is output to the clutch or the brake by switching the garage shift valve, the hydraulic controller inputs the range pressure, which is higher than the SLT pressure, into the control oil chamber and fixes the garage shift control valve.

Abstract: A hydraulic control apparatus for an automatic transmission including a hydraulic pressure source, hydraulic paths, hydraulic servos for operating friction elements which are coupled with the hydraulic source an the hydraulic paths, a control device arranged on the hydraulic paths for operating engagement release through supply/removal of hydraulic pressure to the hydraulic servos and valves which are arranged on the hydraulic path for cutting off hydraulic pressure from the hydraulic pressure source to the hydraulic servo with hydraulic pressure in the downstream side of the control device as signal pressure.

Abstract: A microvalve device for controlling fluid flow in a fluid circuit. The microvalve device comprises a body having a cavity formed therein. An electronically controlled automatic transmission, comprising of an input shaft; an output shaft; a plurality of gears providing driving connection between the input shaft and the output shaft; one of a hydraulically operated brake band and a hydraulically operated clutch which is operable to effect a change in the gear reduction provided by the gears between the input shaft and the output shaft; a source of pressurized hydraulic fluid; and a microvalve device selectively operable to control passage of pressurized hydraulic fluid from the source to the one of a hydraulically operated brake band and a hydraulically operated clutch to operate the one of a hydraulically operated brake band and a hydraulically operated clutch.

Abstract: A second shift valve for a lock-up clutch is switched in response to supply of an R range pressure and a solenoid pressure from a low-and-reverse solenoid valve to selectively supply an output from a lock-up solenoid valve to a pressure reduction control valve or a lock-up control valve. The pressure reduction control valve regulates a line pressure at a small gain by the output from the lockup solenoid valve via the second shift valve. The first shift valve actuated by the solenoid pressure from the low-and-reverse solenoid valve selectively supplies a high R range pressure from a manual valve or an output from the pressure reduction control valve to the low-and-reverse brake. This enables accurate hydraulic control of the low-and-reverse brake and ensures the required torque capacity with simple arrangement.

Abstract: There is provided a hydraulic control device for an automatic transmission, which is comprised of an engagement state determining section and a protection control section. If the engagement state determining section determines that each clutch, which is supplied with a line pressure via a regulating valve having a spool and has an oil pressure switch disposed in an oil channel, is held in an engaged state when gears are not changed, the protection control section sets a command pressure for the regulating valve to a protective oil pressure lower than the line pressure. This brings the regulating valve into a pressure-regulating state to cause lands of the spool to form apertures that reduce hydraulic vibration applied to the line pressure. This inhibits an oil pressure beyond an acceptable value from being applied to the oil pressure switch, and therefore improves the durability of the oil pressure switch.

Abstract: An automatic transmission has a frictionally engaging element, such as a low-and-reverse brake or the like, that is hydraulically actuated for assuming a certain gear position. A hydraulic control system for the transmission comprises a first hydraulic section which produces a line pressure; a solenoid which produces a solenoid pressure; a decompression control valve which receives the line pressure to produce an output pressure while using both the solenoid pressure and the output pressure as signal pressures; a switching valve interposed between the decompression control valve and the frictionally engaging element. The switching valve has a first position wherein the output pressure is fed to the frictionally engaging element and a second position wherein the line pressure is fed to the frictionally engaging element.

Abstract: An automatic transmission controller carries out (a) changing a control for engaging the engaging-side frictional element between in a first condition in which a speed of progression in the shift is managed mainly in accordance with a volume of the hydraulic fluid to be supplied to the engaging-side frictional element itself and in a second condition in which the shift progresses regardless of the volume of hydraulic fluid to be applied to the engaging-side frictional element itself; and (b) accomplishing a volume control for the engaging-side frictional element from a timing immediately after a decision of the shift under a command hydraulic pressure of the hydraulic fluid to be supplied to the engaging-side frictional element in the second condition, the command hydraulic pressure having a lower limit value for securing that a piston stroke of the engaging-side frictional element completes within a predetermined time.

Abstract: An automatic transmission includes a low reverse brake and a reverse clutch that are engaged at different timings to determine a selected gear position, the reverse clutch being engaged immediately before the low reverse brake to be engaged last. It is determined whether or not a piston for actuating the reverse clutch has completed its stroke up to the position where it can start actual engagement. Before determination that the piston of the reverse clutch has completed its stroke up to the position where it can start actual engagement, it is prevented to determine whether or not a piston for actuating the low reverse brake has completed its stroke up to the position where it can start actual engagement.

Abstract: An automatic transmission for a vehicle comprises a torque converter TC equipped with a lock-up clutch 4. This automatic transmission further comprises FIRST˜FOURTH speed clutches 31˜34 for a shift control executing a shift from off-going speed ratio to an on-coming speed ratio by controlling the release of the hydraulic pressure from the off-going clutch and by controlling the supply of the hydraulic pressure to the on-coming clutch. A control system comprises first and second off-going pressure releasing valves 70 and 80, which release the hydraulic pressure from the off-going clutch during the shift, a lock-up control valve 40 and a lock-up timing valve 50, which control the engagement of the lock-up mechanism, and a linear solenoid valve 60, which supplies a control pressure to these valves and controls the operation of these valves.

Abstract: Within the scope of the procedure for improvement of the shifting speed of automatic transmissions, at each gear shift at least one engaging or disengaging shifting element needed for the next gear shift in the same direction is prepared or lowered to shifting pressure during the gear shift in a manner such that when the synchronous rotational speed is reached, it is made possible immediately to carry out the next gear shift.

Abstract: In a control apparatus for an automotive continuously variable transmission having a forward-reverse selector mechanism in which a gear ratio for reverse is set closer to a speed reducing side than a gear ratio for forward and a belt type continuously variable transmission mechanism, a PH pressure that is outputted from a first regulator valve and a PL pressure that is outputted from a second regulator valve are changeably supplied to one and the other of a hydraulic cylinder of a drive pulley and a hydraulic cylinder of a driven pulley via a shift control valve. A hydraulic pressure supplied to a reversing hydraulic pressure connecting element from a reversing manual valve is inputted into an oil chamber of a first regulator valve so that the PH pressure is increased with the hydraulic pressure so inputted.

Abstract: A hydraulic control system for an automatic transmission includes a first clutch acting as an input element at first, second, and third forward speed ranges, a second clutch acting as the input element at third and fourth forward speed ranges, a third clutch acting as the input element at an R range, a fourth clutch operating at P, R, N, and L range for performing an engine brake function by stopping a one-way clutch at the first, second, and third forward speed ranges, a first brake acting as a response element at the P, R, N, and L ranges, a second brake acting as a response element at second and fourth forward speed ranges, a first switch valve for distributing hydraulic pressure controlled by a first solenoid valve to a damper clutch in a torque converter and to clutch control valves for the first clutch, and a second switch valve for distributing hydraulic pressure controlled by a second solenoid valve to the second clutch and the first brake.

Abstract: A microvalve device for controlling fluid flow in a fluid circuit. The microvalve device comprises a body having a cavity formed therein. An electronically controlled automatic transmission, comprising of an input shaft; an output shaft; a plurality of gears providing driving connection between the input shaft and the output shaft; one of a hydraulically operated brake band and a hydraulically operated clutch which is operable to effect a change in the gear reduction provided by the gears between the input shaft and the output shaft; a source of pressurized hydraulic fluid; and a microvalve device selectively operable to control passage of pressurized hydraulic fluid from the source to the one of a hydraulically operated brake band and a hydraulically operated clutch to operate the one of a hydraulically operated brake band and a hydraulically operated clutch.

Abstract: In a control system for a hybrid drive unit, in accordance with applied/released states of engagement elements, there can be set: a forward running range for a forward run by transmitting an input torque to an output member, a backward running range for a backward run by transmitting an input torque to the output member, and a stop range capable of driving one of the power sources by the other. The control system includes a range switching valve activated in response to the individual set ranges for switching and outputting an initial pressure for applying the engagement elements, to a plurality of passages, and adapted, when the stop range is set, to output the hydraulic pressure to the engagement element for establishing a torque transmission passage from one of the power sources to the other and to block the feed of the initial pressure to the engagement element for establishing, when applied, the torque at the output member.

Abstract: An electro-hydraulic control system for an automatic transmission comprises a manual selector valve for operator direction of line pressure fluid to a drive passage when drive is selected or to a reverse passage when reverse is selected. A drive/reverse passage connects the drive passage and the reverse passage. A first check ball is disposed between the drive passage and the drive/reverse passage and a second check ball is disposed between the reverse passage and the drive/reverse passage wherein the check balls operate to pressurize the drive/reverse passage when either drive or reverse is selected.

Abstract: A line pressure control system of an automatic transmission includes a hydraulic pump for generating hydraulic pressure, a regulator valve for adjusting the pressure from the hydraulic pump to a predetermined level, a torque converter control valve for adjusting a partial pressure from the regulator valve, a damper clutch valve receiving the adjusted pressure from the torque converter control valve for feeding the pressure to a damper clutch, a damper clutch solenoid valve for controlling the damper clutch valve, a reducing valve for reducing a partial pressure from the regulator valve and then supplying the reduced pressure to the damper clutch control valve, wherein the regulator valve includes a valve body, first and second valve spools coaxially inserted into the valve body, a sleeve encapsulating the second valve spool, and a coil spring interposed between the first and the second valve spools.

Abstract: A hydraulic control system includes a pressure/damper clutch controller, a pressure reducer, and a shift controller. The shift controller includes a manual valve indexed with a driver-controlled select lever to supply hydraulic pressure to the hydraulic pressure controller, the hydraulic pressure distributor, and the friction elements.

Abstract: The patent offers a method of driving a vehicle having an automatic transmission. According to the method, an electronic control device is put in with a clutch pressure through the loading standing device of a clutch. The clutch pressure is isolated according to the gearbox input factor and a gear as a characteristic curve in an electronic driving device. The clutch pressure of a clutch along the power flow is defined during the motion outside the gear change according to the real transmission capability of the clutch.

Abstract: A unique regulator valve arrangement is provided for an automatic transmission which provides variable line pressure. The line pressure is actively regulated through the regulator valve configuration with a variable force solenoid. The arrangement allows line pressure to be maintained at a minimal value according to a given condition while avoiding clutch slip.