Abstract: A continuously variable transmission in a motor vehicle is regulated using a controller comprising a first control circuit as a speed controller for regulating the transmission input speed as the product calculated from the transmission output speed and the transmission ratio, complete with a summation element at the controller input as well as with a control element, and a second control circuit post-connected to the first control circuit as a speed gradient controller for regulating the time derivative of the transmission input speed, complete with a summation element at the controller input.

Abstract: A hydromechanical torque sensor having several plenum chambers can be utilized to transmit torque between the driving and driven parts in the power train of a motor vehicle as well as to make necessary adjustments in a hydraulically adjustable transmission. To this end, the plenum chambers of the torque sensor can be connected to or sealed from each other. The torque sensor and the transmission can receive fluid from discrete sources or from a single source by way of suitable valves.

Abstract: A basic speed change ratio is set on the basis of vehicle speed and throttle valve opening, and a control target speed change ratio is made to gradually approach the basic speed change ratio in accordance with a speed change speed. Feedback control is then carried out so that the actual speed change ratio coincides with the control target speed change ratio. When there is an up-shift requirement with a rate of change in throttle valve opening equal to or less than a predetermined value, and a rate of change in the basic speed change ratio, which is set on the basis of operating conditions, equal to or less than a predetermined value, the speed change speed is faster than at the time of an up-shift requirement with throttle valve closure.

Abstract: A continuously variable transmission has springs, which urge the movable sheaves of primary-side and secondary-side pulleys, set to achieve a pulley ratio r.sub.1 approximate to or within a predetermined range of a neutral pulley ratio r.sub.N so that a vehicle takeoff response delay is eliminated when the driver shifts the transmission from a vehicle stop range (the P or N range) to the drive range (D range). This setting prevents a vehicle from moving backward when the driver shifts from the vehicle stop range to the D range immediately after starting the engine. The pulley ratio r.sub.1 can be achieved either before or after the minimum required fluid pressure is supplied.

Abstract: A continuously variable transmission includes a main shaft having a stepped portion in the vicinity of an end thereof, stationary and movable flanges, and a stopper for preventing a movement of the movable flange. The stepped portion of the main shaft, an end of the movable flange, and the stopper cooperate to define a space around the main shaft.

Abstract: A pulley, in particular for a continuously variable transmission, provided with two sheaves placed on a pulley shaft, at least one sheave being movable in the axial direction relative to the pulley shaft by movement structure. This movement structure includes at least one piston/cylinder assembly, and also fixing structure which fixes the movable sheave in the direction of rotation relative to the pulley shaft. According to the invention, the fixing structure is fitted at least inside a cylinder of the piston/cylinder assembly.

Abstract: A continuously-variable-ratio transmission ("CVT") of the band-and-sheave type capable of "torque control", so that what the operator demands, by movement of the accelerator pedal or other control member, is a particular driving torque applied to the ratio-varying components ("variator") A connection (21, 22) between at least one of the variator sheaves (3, 4) and its shaft (5) is torque-sensitive, so that torque at that sheave generates an axial force which is a function of the magnitude and direction of the torque to which the sheave is subjected. Examples are described in which the operating axial load, applied to the variator pulley units, comprises two parts--a first part to maintain traction between sheaves and band, and a second part related to the applied torque--and a variator using more than one band.

Abstract: A continuously variable transmission, in particular for a motor vehicle, provided with a control for the transmission ratio of the transmission, which control in a first operating mode controls the transmission ratio on the basis of one or more input signals and in a second operating mode controls the transmission ratio, for example on the basis of an external signal originating from the driver of the motor vehicle, along one or more control curves of one or more sets of control curves, possibly within rotational speed limits imposed on the input speed of the transmission. One or more control curves and/or one or more rotational speed limits are a function of the input speed of the transmission in such a way that, in accordance with those functions, the input speed of the transmission is not zero for a notional output speed of the transmission of zero. In this way the drive characteristics of the transmission are appreciably improved, coupled with improved efficiency and optimum power.

Abstract: A torque transmitting power train for use in a motor vehicle employs a transmission with two adjustable pulleys and an endless flexible element trained over the pulleys. The pulleys are adjustable by a torque sensor and primary hydraulic adjusting units in dependency upon the magnitude of transmitted torque, as well as by an adjustable selecting valve and secondary hydraulic adjusting units in dependency upon the desired or required transmission ratio. The primary and secondary adjusting units can receive a pressurized hydraulic fluid from a common source.

Abstract: A hydromechanical torque sensor having several plenum chambers can be utilized to transmit torque between the driving and driven parts in the power train of a motor vehicle as well as to make necessary adjustments in a hydraulically adjustable transmission. To this end, the plenum chambers of the torque sensor can be connected to or sealed from each other. The torque sensor and the transmission can receive fluid from discrete sources or from a single source by way of suitable valves.

Abstract: A basic speed change ratio is set on the basis of vehicle speed and throttle valve opening, and a control target speed change ratio is made to gradually approach the basic speed change ratio in accordance with a speed change speed. Feedback control is then carried out so that the actual speed change ratio coincides with the control target speed change ratio. When there is an up-shift requirement with a rate of change in throttle valve opening equal to or less than a predetermined value, and a rate of change in the basic speed change ratio, which is set on the basis of operating conditions, equal to or less than a predetermined value, the speed change speed is faster than at the time of an up-shift requirement with throttle valve closure.

Abstract: In a shifting device such as generally used in automatic transmissions, a regulating device (15) is provided by the swiveling of which to a shifting gate (13) the automatic multiplication stages can be preselected. Besides, the regulating device can be transferred to a second shifting gate (14) via a transverse gate (17). According to the invention, in the second shifting gate (14) a characteristic field (1) is influenced by a continuously variable incremental or decremental change of individual operation parameters or a combination of at least two parameters. The operation parameters consist of the engine speed, the transmission ratio and the output speed.

Abstract: The invention relates to a method for influencing the tension in a drive belt in a continuously variable transmission. According to the invention, the tensions in the drive belt are determined as a function of the speed of the drive belt. For part, parts or the entire range of the possible input speeds of the transmission, the input speed of the transmission is then increased and/or reduced to a desired speed range for the drive belt with an essentially relatively lower tension in the drive belt. The power density, the efficiency and the control range of the transmission can be improved by application of this method.

Abstract: A valve body assembly for an automatic transmission formed by superimposing and clamping a torque converter casing, a first separation plate, a main valve body, a second separation plate, a second valve body, a third separation plate and a servo body. Pairs of first separation plates and pairs of second separation plates are provided, one pair for 7-position types of automatic transmissions and another pair for 6-position types of automatic transmissions and are, respectively, selected, used and assembled between the converter casing and main valve body and the main valve body and second valve body depending upon whether a 7-position type of transmission or a 6-position type of transmission is being assembled. Thus, general purpose properties are provided to the valve body assemblies used in hydraulic pressure control systems for 7-position type and 6-position type automatic transmissions for vehicles and the like.

Abstract: Pulley, in particular for a continuously variable transmission. The pulley is provided with two discs on a pulley shaft, at least one disc being axially movable relative to the other disc by means of control means. The movable disc is connected to the pulley shaft by means of a key/groove connection. A radially inward profile of the key/groove connection is connected to the disc, and a radially outward profile of the key/groove connection is connected to the shaft.

Abstract: A power train for use in motor vehicles has an infinitely variable transmission with two adjustable sheaves, an endless flexible torque transmitting element trained over the sheaves, and at least one hydraulic adjusting unit for each of the sheaves. The adjusting units receive pressurized fluid from a pump and the pressure of such fluid, and hence the extent of frictional clamping engagement between the sheaves and the flexible element, is regulated by a torque sensor including a plenum chamber with an outlet having an effective cross-sectional area which is variable in dependency upon variations of torque being applied to the torque sensor by the engine of the vehicle. The energy of fluid leaving the plenum chamber is used to operate a jet pump which draws fluid from a source for lubrication and/or cooling of the transmission and/or one or more clutches forming part of the power train.

Abstract: The gear ratio of a belt-type continuously variable transmission is changed by increasing or decreasing the hydraulic pressure applied to an oil chamber for a drive pulley by a ratio control valve. A spool of the ratio control valve is driven by a normally opened solenoid valve and a normally closed solenoid valve. In a lower gear ratio range, the gear ratio is controlled by controlling the duty rate of the normally opened solenoid valve, and in a higher gear ratio range, the gear ratio is controlled by controlling the duty rate of the normally closed solenoid valve. When any trouble is generated, the gear ratio is held at an intermediate value by bringing both the duty rates of the normally opened solenoid valve and the normally closed solenoid valve into 0% or 100%. Thus, it is possible to finely control the gear ratio of the belt-type continuously variable transmission and, when any trouble is generated, the gear ratio can be held at the value intermediate between a LOW value and an OD value.

Abstract: A pulley thrust pressure control apparatus for a belt-type continuously variable transmission comprises a pulley thrust pressure valve unit 40 for setting a low pulley thrust control pressure and a high pulley thrust control pressure greater than the low pulley thrust control pressure; a shift valve 53 for supplying the low and high pulley thrust control pressures selectively into drive and driven cylinders 14 and 19 of drive and driven pulleys in correspondence with the position of a spool thereof; a drive pressure feedback passage 39c for causing the pressure inside the drive cylinder 14 to act on the spool as a positional control force; and a driven pressure feedback passage 39d for causing the pressure inside the driven cylinder 19 to act as a positional control force on the spool in the direction opposite of that cause by the pressure from the drive pressure feedback passage.

Abstract: A device is proposed to determine the rotational speed of a transfer element (3) arranged in variable-diameter pulleys (1, 2) of a continuously variable transmission system, the said device Consisting of a sliding stock (4, 15), with a sensor (10, 16) which is supported on the transfer element (3) on the inner sides of the variable-diameter pulleys, which sliding stock is connected to the transmission case (8) by a spring (6) loaded rocker arm (5) mounted in a swivelling joint (7).With the knowledge of the peripheral speed of the transfer element (3), the rotary speeds (N1, N2) of the set of variable-diameter pulleys (1, 2) and the effective transmission radii (r1, r2), the slippage can be determined between the transfer element (3) and the sets of variable-diameter pulleys (1, 2).

Abstract: A pulley device for a continuously variable transmission includes a shaft having first and second ends, the second end being formed with two axially separated ring grooves. A C-shaped ring is engaged with one of the two ring grooves disposed near to a movable conical plate. A ring-shaped retainer is arranged to restrain radial movement of the C-shaped ring. A snap ring is engaged with the other of the two ring grooves to restrain an axial position of the retainer.

Abstract: The invention improves the driveability of a vehicle by controlling a target engine speed according to an engine load and a vehicle running condition to ensure an actual engine speed. In controlling a speed ratio of a continuously variable transmission, an adaptation factor is used for deciding a target engine speed, the adaptation factor is determined according to constants, an average engine load and an average vehicle speed change quantity. Even when the average engine load changes because of fluctuation in an accelerator opening, various running modes can be decided by the adaptation factor depending upon both the average engine load and the average vehicle speed change quantity, thereby improving driveability upon changing speed of the continuously variable transmission.

Abstract: In a vehicle travelling by use of a travelling drive source such as an engine or a motor, the gear shift ratio of a continuously variable transmission B can be changed by increasing or decreasing the width of a groove in a driving pulley 19 of the continuously variable transmission B by a gear shift ratio changing device 61 using a motor 62 as a drive source. The motor 62 is controlled on the basis of output signals from a throttle opening degree sensor, an engine rotational speed sensor and a vehicle speed sensor, thereby enabling an energy-saving travelling suited to an operational condition of the travelling drive source or a travelling condition of the vehicle. The gear shift ratio changing device 61 is supported in a floating manner within a casing 3, 8 for the continuously variable transmission B.

Abstract: A process to adjust the pretensioning force for the transmission element of a continuously variable transmission, complete with two disc assemblies comprising two discs each, will be described. For optimized specification of the pretensioning force, the following process steps will be provided:a) determining transmission element length,b) specifying a start value for the pretensioning force,c) reducing the pretensioning force and determining transmission element virtual length,d) determining transmission element slip status by comparing actual length and virtual length of the transmission element,e) changing pretensioning force in relation to slip status, whereby, if actual length and virtual length of the transmission element correspond, the pretensioning force will be decreased, and, if actual length and virtual length of the transmission element differ, the pretensioning force will be increased.

Abstract: A full time four-wheel drive system for a vehicle is described which utilizes a unique torque distributor subassembly which provides a torque differentiation function as well as a speed ratioing function, thereby permitting utilization with a torque transmitting subassembly which is greatly simplified relative to a conventional transmission. The torque distributor subassembly includes an input shaft for receiving output torque from a torque transmitting subassembly of a vehicle, a plurality of output shafts and means for connecting the input shaft to each of the output shafts. The connecting means comprises a plurality of continuously variable belt drives, each having a drive pulley mounted on the input shaft and driven thereby and a driven pulley mounted on one of the output shafts with the pulleys carrying a belt therebetween. Each pulley comprises a pair of sheaves which are axially moveable in relation to one another.

Abstract: A supercharging device including an actuator for controlling return force of a resilient member in a continuously variable transmission (CVT) with a flyweight and a resilient member is provided. The actuator is employed so that a movable flange slides along the axis thereof away from a fixed flange in a drive pulley of the CVT when under a light load for which auxiliary machinery such as a supercharger driven by the CVT requires little driving force. The actuator is installed inside an input pulley through which the driving force of the engine is transmitted to the drive pulley.

Abstract: A pulley device includes a moveable conical pulley component which is moveable to a stationary conical pulley component by a servo motor. The servo motor includes a cylinder fixedly held with respect to a shaft portion of the stationary conical pulley component, and a piston fixed to the moveable conical pulley component and slidably engaging the cylinder. The servo motor also includes an auxiliary cylinder reduced in diameter than the cylinder and fixed with respect to the shaft portion, and an auxiliary piston fixed to the moveable conical pulley component. The auxiliary piston is received in the auxiliary cylinder.

Abstract: In a pulley unit of belt-type continuously variable transmission, wherein a movable sheave on a pulley shaft is moved toward and away from a stationary sheave by means of a hydraulic servo device, and a movable cylinder secured to the movable sheave defines a hydraulic chamber between itself and a stationary plunger on the pulley shaft. The movable cylinder is of a ring-shape having an enlarged-diameter cylindrical portion, a reduced-diameter cylindrical portion, and a back wall portion integrally joining the two cylindrical portions radially. The reduced-diameter cylindrical portion is fitted on a hub of the movable sheave. A detachable cover member is provided around the cylinder and the plunger to define a hydraulic balance chamber. The movable sheave can be used commonly for different sizes of the movable cylinder, and the interior of the servo device can be exposed for maintenance by removing the cover member.

Abstract: The variable speed transmission is for transmitting a torque produced by an engine to a belt. The transmission comprises a shaft connected to the engine, a fixed flange and a movable flange slidably connected to the shaft and substantially rotatable thereon. The flanges define therebetween a groove for receiving the belt. A pressure device is rigidly connected to the movable flange. The pressure device has a pair of pressure units diametrically opposed for pressurizing fluids. Each pressure unit comprises a first fluid chamber, a second fluid chamber, a radially movable partition separating the first fluid chamber from the second fluid chamber, resilient means for applying a return force toward the shaft counterbalancing the centrifugal force, and a fixed partition rigidly connected to the shaft. The fixed partition also separates the first fluid chamber from the second fluid chamber.

Abstract: A supercharging device for an internal combustion engine for which the load can be changed by an accelerator pedal includes: a continuously variable transmission being driven by the engine and including a drive pulley, a driven pulley, a belt, a flyweight, and a presser member, the drive and driven pulleys having movable flanges and fixed flanges mounted on rotatable shaft members and being rotatable therewith, the belt being wound around and coupling the drive and driven pulleys, and the flyweight and the presser member being provided on at least one of the drive pulley and the driven pulley; and a mechanical type supercharger driven by the continuously variable transmission for supercharging the engine, the supercharger having a housing and a runner shaft with a runner rotatably supported inside the housing.

Abstract: A cone disc transmission is presented which is infinitely adjustable and includes the production of axial pressure forces of the cone discs on pulling member rotating between these cone discs via hydraulic tensioning member. The tensioning member, which are arranged on the transmission shafts, each axially influence one of the cone discs which are displaceably arranged on the respective transmission shaft. By way of a control valve, the tensioning member and the pressure medium conduits connected thereto are charged by a pressure medium which is supplied by a pump. A torque disposed on the drive shaft of the transmission in the reflux of the control valve throttles the reflux of the pressure medium as a result of the torque-dependent movement of two valve members relative to one another and as a function of the load and thus determines the basic pressure of the system.

Abstract: In a continuously variable transmission which is provided with a primary pulley and a secondary pulley, between which a driving belt is mounted, primary and secondary control systems, which are coupled to the respective pressure chambers of the axially translatable pulley discs, are employed to precipitate current pressure values, in dependence upon desired pressure values. To this end, the control system employs a regulator to which only the difference between the desired and the measured pressure-value is supplied, whereby the regulator nevertheless only has to regulate the relatively rapidly changing variation in a rest value supplied separately by a rest state device. This greatly improves the dynamic behaviour of the controller, so that rapid variations in the desired value of the entrant pressure can be effectively followed by the control system.

Abstract: A supercharging device for an internal combustion engine includes a runner for compressing air, a driven pulley for rotating the runner, and a drive pulley for rotating the driven pulley. The drive pulley has a fixed sheave and a movable sheave movable in an axial direction with respect to the fixed sheave. A belt is wound around the driven pulley and the drive pulley. A control device is for moving the movable sheave in an axial direction so that the movable sheave is moved away from the fixed sheave under a low load condition and that said movable sheave is moved towards the fixed sheave under a high load condition.

Abstract: A hydrostatic continuously variable transmission includes a closed hydraulic circuit comprising a hydraulic pump, a hydraulic motor, and an oil supply passage connected between the hydraulic pump and the hydraulic motor. The hydraulic pump selectively generates a first oil pressure lower than a first predetermined pressure level, a second slowly-changing oil pressure higher than the first predetermined pressure level when the transmission is in normal operation, and a third rapidly-changing oil pressure higher than a second predetermined pressure level higher than the first predetermined pressure level when the transmission starts to operate.

Abstract: Transmission unit consisting of a continuously variable transmission (1); a hydraulic cylinder/piston unit (3) to set the transmission ratio of the continuously variable transmission (2); a pressure compensation chamber (4) working in conjunction with the cylinder/piston unit (3); and a passage organ (5) having at least one passage way (6) connecting the pressure compensation chamber (4) with the piston chamber (7) of said cylinder/piston unit (3), characterized in that the passage way (6) stretches at least partially along the outer surface of the passage organ (5).

Abstract: A drive system for driving an engine auxiliary equipment has a first power transfer device for transferring an output torque of the crankshaft to an interim shaft at all time and a second power transfer device comprising a crank pulley mounted for relative rotation on the crankshaft, an interim pulley mounted for relative rotation on the interim shaft and an input pulley related to the auxiliary equipment all of which pulleys are operationally coupled by a belt so as to transfer an output torque of the crankshaft to the auxiliary equipment. A first clutch is disposed between the crankshaft and crank pulley so as to connect and disconnect a transfer of power between the crankshaft and crank pulley. A second clutch is disposed between the interim shaft and interim pulley so as to connect and disconnect a transfer of power between the interim shaft and interim pulley.

Abstract: A variable diameter belt type power transfer assembly having a drive sheave and a driven sheave, both of which are adjustable and include a pair of opposing coaxial flanges, one of which is axially movable relative to the other, is disclosed wherein both flanges of the drive sheave are provided with first and second belt engaging surfaces flaring radially outwardly with respect to each other so as to define first and second variable diameter belt receiving grooves therebetween. A dual range of velocity ratios between the drive sheave and the driven sheave is obtainable by selectively positioning a drive belt in the respective variable diameter belt receiving grooves. The inner and outer flange portions of one sheave member are constructed to allow the outer sheave portion to be selectively located in an operative position and an axially spaced retracted position relative to the inner sheave portion.

Abstract: A control system for a belt-type continuously variable transmission of a motor vehicle, having a primary and a secondary control valve for varying the transmission ratio. The primary control valve receives an electric signal from a control unit to vary a primary hydraulic pressure. The primary control valve produces a primary pressure which causes the transmission to take an intermediate transmission ratio when the electric signal is not transmitted due to a failure such as breakage of a cable. Thus, dangerous situations of the vehicle are prevented, and the vehicle can reliably start in a relatively low speed range of the transmission.

Abstract: A continuously variable transmission having a belt ratio measurement system. The continuously variable transmission contains a moveable sheave and a fixed sheave. The measurement system includes two tone wheels and pickups. The first tone wheel is mounted to the fixed sheave with a corresponding first pickup mounted proximate thereto. The second tone wheel is mounted to the moveable sheave with a corresponding second pickup mounted proximate thereto. The second tone wheel has angled teeth so that the signal sensed in the second pickup varies in relation to the axial position of the moveable sheave. By comparing the signal sensed by the first pickup with the signal sensed by the second pickup, the axial position of the moveable sheave, and thus the belt ratio of the transmission, may be determined.

Abstract: A continuously variable speed transmission with first and second adjustable sheaves and an endless flexible element which is trained over the sheaves. A torque sensor is installed between a prime mover and the shaft for the first sheave to determine the axial position of the axially movable flange of the first sheave in dependency on the transmitted torque and the selected transmission ratio. The torque sensor employs an annulus of spherical rolling elements between the surfaces of two ramps one of which is movable axially of the shaft for the first sheave to initiate controlled radial and/or axial movements of the rolling elements. The surfaces of the ramps generate torque- and transmission ratio-dependent forces.

Abstract: A controlling device for controlling the transmission ratio of a non-stage transmission in a vehicle. The transmission ratio is controlled according to a forecast output power of the vehicle. The output power is forecast based on an operating condition of the vehicle, such as atmospheric pressure. The control considers various operating parameters. A comparison of a predetermined ratio of increase of engine speed or throttle opening with actual ratios of increase of engine speed or throttle opening may be made in controlling the transmission ratio. An uneven road surface is detected and a transmission ratio of the transmission is controlled accordingly to substantially eliminate hunting. An engine speed is controlled so that the engine speed may not exceed a predetermined rotational speed when the transmission gear ratio is fixed.

Abstract: A control system for a continuously variable transmission reduces the noise generated as a result of the use of an articulated belt for connecting the first and second variable pulleys. The control system dithers the ratio set point in order to prevent a cyclic repetition of the forces between the belt and the pulleys. This reduces the amplitude of noise peaks generated at discrete frequencies by operation of the transmission resulting in a decrease in the level of perceived noise.

Abstract: A method for regulating an automatic transmission unit having a plurality of coupling devices includes supplying a hydraulic medium to a control element; and supplying at least a portion of the hydraulic medium to a hydraulic regulating valve. The control element determines the portion of the hydraulic medium supplied to the hydraulic regulating valve and supplies that portion to the hydraulic regulating valve. The hydraulic regulating valve regulates an operational function of one of the coupling devices. When the central element fails, a safety device regulates the operational function of one of the coupling devices as a function of the revolution speed of a shaft of an engine.

Abstract: The invention concerns a drive device (7) with variable transmission ratio for driving an auxiliary aggregate of a motor vehicle. A belt pulley (11) of the drive device (7) has a chamber (38) connected to a reservoir (30) of a hydraulic medium. The centrifugal action of the hydraulic medium contained in the chamber (38) is used to change the speed of the driven shaft (13). By applying a supporting pressure to the chamber (38), it is possible additionally to vary the output speed of the drive device (7).

Abstract: A continuously variable transmission includes an improved secondary servo arrangement in order to provide the necessary clamping forces for high torque conditions. The secondary servo includes a plurality of fluid chambers in order to allow an increase in the area for application of fluid pressure. Fluid conduits between the chambers permit communication of the fluid to the chambers to regulate the clamping force of the movable sheaves of the secondary variable pulleys.

Abstract: A control valve in an automatic transmission is operated by a solenoid-operated relief valve. A flow rate of the oil through the control valve is calculated. A correcting value is calculated from the calculated flow rate so as to control pressure override of the relief valve to a predetermined value. A solenoid current applied to a solenoid of the relief valve is corrected with the calculated correcting value.

Abstract: Device for the regulation of a continuously variable transmission in motor vehicles, characterized in that it mainly consists of means for the supply of a hydraulic medium under pressure; control means for the regulation of a pressure; and a controller (13) formed of on the one hand a main valve (14) for the supply and discharge of the hydraulic medium to the regulating cylinder (8) of the continuously variable transmission (1), and on the other hand a control valve (15), whereby the valve bodies (16, 17) of the main valve (14) and the control valve (15) cooperate by means of elastic means, whereby the valve body (16) of the main valve (14) is loaded by a pressure regulated by the control valve (15) and whereby the valve body (17) of the control valve (15) is loaded by a pressure set by means of the above-mentioned control valves.

Abstract: A solenoid operated control valve in an automatic transmission is operated by dither current. A flow rate of oil through the solenoid operated control valve is calculated. At least either one of the frequency and amplitude of the dither current is corrected by the flow rate. The solenoid operated control valve is operated by the dither current.

Abstract: A hydraulic control apparatus for controlling a vehicle power transmitting system including a belt-and-pulley type continuously variable transmission and a torque converter provided with a lock-up clutch. The transmission includes a pair of hydraulic actuators one of which receives a belt tensioning pressure for controlling a tension of a transmission belt.

Abstract: A hydraulic control apparatus for controlling a belt-and-pulley type continuously variable transmission of a motor vehicle having an engine, which transmission includes a pair of hydraulic actuators one of which receives a belt tensioning pressure for controlling a tension of a transmission belt. The hydraulic control apparatus includes an engine-output detecting valve for generating an engine output pressure indicative of a currently required output of the engine, a solenoid-operated valve for regulating a modified engine output pressure based on the engine output pressure generated by the engine-output detecting valve, and a pressure regulating valve for regulating the belt tensioning pressure based on at least the modified output pressure. The modified engine output pressure is obtained so that the belt tensioning pressure is controlled to an optimum level.

Abstract: A continuously variable belt or chain transmission wherein the input shaft carries a first adjustable sheave and the output shaft carries a second adjustable sheave. The axially movable flanges of the sheaves are displaceable toward the associated fixedly mounted flanges by hydraulic cylinder and piston units. The pressure of fluid in such units is regulated by a torque sensor which is a hydrostatic pump installed between a prime mover and the input shaft and further serves as a means for eliminating peaks of transmitted torque and/or as a clutch. A second pump is provided to supply pressurized fluid to one or more additional cylinder and piston units which are used to change the ratio of the transmission. The cylinder and piston unit for the axially movable flange of the sheave on the output shaft can contain a diaphragm spring serving to permanently bias the respective movable flange against an endless belt or chain which is trained over the sheaves.