Abstract: An electro-hydraulic control system with electronic control for a gearbox includes at least one actuator element device for receiving an analog measuring signal from the actuator element(s), a device for forming an actual actuator value from the analog measuring signal for the regulation of the actuator element(s), a computing device with a memory, and an output driver. At least one A/D converter is provided to convert the actual analog actuator element value (U1) and/or the analog actuator element measuring value into a digital value. A digital two-step controller regulates the actuator element(s) by a cyclically-called comparison of theoretical and actual values.

Abstract: When a slip control system is not operating, a speed ratio control device uses a sensor detected vehicle speed for speed ratio control, and when the slip control system is operating, it uses an estimated vehicle speed for speed ratio control. It is determined whether a variation amount of the estimated vehicle speed is greater than a threshold set to a variation amount which could not be obtained when there is no error. When the variation amount of the estimated vehicle speed is greater than the threshold, it is determined that the estimated vehicle speed is abnormal, and use of the estimated vehicle speed for speed ratio control is prohibited.

Abstract: After the engine rotational speed Ne has become below a reference rotaional speed Neo, which is lower than an idling rotational speed of the engine, and after the pressure PL of oil passages 103a and 103b has begun to decrease, for a predetermined time, the currents supplied to electromagnetic valves 45 and 46 are adjusted to generate, in each electromagnetic valve, a second biasing force electromagnetically in a magnitude that can supplement a decrease in a third biasing force which is generated by the back pressure led through an oil passage 107 and 108, respectively, and which decreases as the pressure of the oil passages 103a and 103b decreases. After the above metioned predetermined time has elapsed, the currents supplied to the eletromagnetic valves 45 and 46 are set almost to zero.

Abstract: A transmission mechanism of continuously variable transmission in a vehicle comprises a primary pulley and a secondary pulley provided with a first cylinder chamber and a second cylinder chamber, with groove widths being changed by supply of hydraulic pressure, and a belt provided between the pulleys. A hydraulic pressure to the first cylinder chamber is controlled by CVT control unit through a shift control valve according to a driving state of the vehicle, and the second cylinder chamber is continuously supplied with a line pressure. CVT control unit includes an internal memory to retain a heavy-current system fail flag according to the failure information inputted from a motor control unit.

Abstract: A shift control apparatus of a continuously variable transmission for a vehicle comprises sensors for detecting operating conditions of the transmission and a motor connected to the transmission. A controller of the shift control apparatus stores different shift maps and employs one of them according to a driver's command or vehicle driving condition. The controller decides a target value of an input rotation speed of the transmission from an output rotation speed of the transmission and the load condition of a motor on the basis of the shift map and continuously changes a gear ratio of the transmission so that the transmission input rotation speed is adjusted to the target value. The controller can change the rate of the shift speed indicative of a time period of a gear ratio changing operation according to a driver's command.

Abstract: In a vehicle transmission wherein plural speed change ratios from a largest speed change ratio to a smallest speed change ratio are selectively applied according to a command input by a driver, a real speed change ratio of the transmission is detected. It is determined whether or not the transmission is performing a shift-down based on the input command and the real speed change ratio. A shift-down limit speed change ratio is determined based on the speed change ratio before the shift-down operation is performed, and when the engine brake of the vehicle is operating, the transmission is controlled so as not to apply a speed change ratio larger than this shift-down limit speed change ratio. Due to this, the driver does not experience an excessive engine braking sensation even when an extreme speed change command is issued.

Abstract: A speed change ratio of a stepless transmission of a vehicle is controlled so as to decrease the greater the vehicle speed, but this control of speed change ratio is suppressed when the drive wheels are slipping. This prevents misinterpretation of the slipping of the drive wheels as an increase of vehicle speed, and prevents shift-up of the transmission when the drive wheels are slipping.

Abstract: A slip of drive wheels of a vehicle driven via a continuously variable transmission is suppressed due to fuel cut of a multi-cylinder engine. The speed change response characteristics of the transmission are made to vary according to the engine rotation speed when fuel cut is performed. A speed change ratio command value is calculated from a target speed change ratio based on a first-order delay due to a predetermined time-constant. The response of the transmission is thus delayed for low engine rotation speed than for high rotation speed, and undesirable fluctuation of the speed change ratio when the drive wheels slip is prevented.

Abstract: A system for controlling motive force of a vehicle having an engine and an automatic transmission connected to the engine to transmit engine torque to a drive shaft of the vehicle, wherein a control mode is selected from among a plurality of predetermined control modes in response to a calculated desired motive force and vehicle speed such that the fuel economy is enhanced and engine torque and speed (gear) ratio are controlled in response thereto. Moreover, the desired motive force is calculated by obtaining a difference between the wide-open-throttle motive force and the full-closed-throttle motive force and by multiplying the difference by a calculated ratio of motive force. Furthermore, the calculated desired output of the engine and the desired gear ratio are controlled such that the desired motive force is generated when the desired motive force is discriminated to be achievable.

Abstract: In a neutral N control for substantially equalizing axial forces to act on two pulleys, a belt type continuously variable transmission (CVT) self-converges into the gear neutral point (GN) at which the output shaft RPM takes the value 0. When the convergence is made to the GN point to establish a no-load state, the CVT establishes a force F.sub.A to converge into a pulley ratio of 1.0, in which it is stabilized by itself. A converging force F.sub.N to the GN point and the force F.sub.A toward the pulley ratio of 1.0 are repeated in a vortex shape in the load state and in the no-load state to establish a creep force. This creep force can be modified by generating a force F.sub.O against the force F.sub.A.

Abstract: A pressure controlling system for a CVT of the belt with bevelled pulley type is proposed in which, on detection of a shift from the neutral or park position, the pressure in the primary and secondary pulleys is raised to a first level. This ensures that the variator (1) can transmit the full torque on initiation of a drive operation.

Abstract: The invention proceeds from an arrangement or a method for adjusting the transmission ratio of a continuously variable belt transmission having a drive end and an output end. The drive end and the output end have at least one axially displaceable element which has essentially the form of a conical disc. Via sensor means, an rpm signal is detected, which represents the rotational movement of the drive end or the output end, and, on the other hand, a displacement signal is detected which represents the axial displacement of at least one of the axially displaceable elements. The essence of the invention is that means for adjusting the transmission ratio are provided with the aid of which the adjustment takes place at least in dependence upon the detected displacement signal. An advantage of the invention is that, in this way, the possibility is provided to save one rpm sensor.

Abstract: The invention relates to a method for controlling a continuously variable transmission with an electrohydraulic control, a selector device, and a controllable engaging clutch of a motor vehicle, especially one powered by an internal combustion engine, with a control device in a first operating mode automatically selecting and adjusting a gear ratio for the transmission from signals of the selector device and the operating parameters of the motor vehicle such as the throttle angle, driving speed and engine rpm, by means of curves selectable by the driver.It is proposed, in a second operating mode, to simulate a multi-step transmission influenceable directly by the driver. In order to permit use of this operating mode, only a few preset gear ratios are made available to the driver.

Abstract: According to a torque converter lockup control, a lockup actuator, including a lockup solenoid, is operative responsive to an output command signal issued by a controller to adjust lockup clutch engagement force to a commanded value. The lockup clutch engagement force is a force with which the lockup clutch is engaged. The controller determines the commanded value as a function of a deviation between a current value of slip speed within the torque converter and a desired value thereof. For preventing the lockup clutch from shifting deeply into its converter position when the deviation persists to stay in the neighborhood of zero, the controller sets a limit to the determined commanded value during operation of the lockup clutch in the slip lockup mode.

Abstract: An electronic transmission control system having a fail-safe system for an automotive vehicle with a continuously variable automatic transmission whose speed-change ratio is changeable continuously depending on vehicle speed and engine load, comprises a hydraulic modulator producing at least a regulated line pressure necessary to adjust the speed-change ratio hydraulically, a desired speed-change ratio arithmetic processing section for calculating a desired speed-change ratio based on the vehicle speed and the engine load, and a desired line pressure arithmetic processing section for calculating a desired line pressure based on the desired speed-change ratio and the engine load.

Abstract: A control system controls the output of a power source of a vehicle having a continuously variable transmission and a gear ratio to be set by the continuously variable transmission. The control system determines a target driving force on the basis of an output demand and a vehicle speed, and determines a target output of the power source for achieving the target driving force. The control system determines a target output speed preset for the target output, and controls the gear ratio of the continuously variable transmission so that the actual output speed of the power source may become the target output speed. The control system further determines the target output torque of the power source on the basis of the target output and the actual output speed of the power source, and controls the power source to achieve the target output torque. When the gear ratio is to be changed, its changing rate is made different in at least two quick and slow states.

Abstract: In an engine provided with a throttle valve actuator which controls the opening/closing of the throttle valve, a target throttle valve opening degree is determined based the amount of accelerator pedal depression. Following a speed change command being issued in an automatic transmission the target throttle position is gradually decreased until an inertial phase is detected. The target throttle opening is then returned to that which corresponds to the accelerator pedal depression by the driver.

Abstract: A drive device for an engine-driven load, which in the drive direction successively includes an engine, a torque converter with an input shaft and an output shaft, and a continuously variable transmission unit with a primary shaft and a secondary shaft, between which torque can be transmitted with the aid of friction forces. The nominal torque which can be generated by the combination of engine and torque converter on the primary shaft of the transmission unit is greater than the maximum slipping torque of the transmission unit. The device is provided with devices which act on parts of the drive device in such a manner that the torque which can actually be generated in operation by the combination of engine and torque converter on the primary shaft of the transmission unit is limited. The limited level for the torque is controlled in such a manner that the torque generated is at most equal to the maximum slipping torque of the transmission unit.

Abstract: A speed change ratio of a continuously variable transmission comprising a V-belt looped around a pair of variable pulleys for varying the speed change ratio according to a first and second oil pressures. A speed change control valve converts a first oil pressure from an oil pressure supply unit to a second oil pressure based on a speed change ratio command value. The speed change ratio command value is calculated by a microprocessor according to a real speed change ratio and dynamic characteristics of the transmission. By calculating the dynamic characteristics according to the real speed change ratio and the first oil pressure, a set response of the transmission is always obtained regardless of fluctuations of the first oil pressure.

Abstract: A variable control device which controls the rotations of a step motor in a continuously variable transmission and maintains the variable ratio is provided with a feed back control system and a feed forward control system. These control systems are switched on the basis of the driving conditions. The feed back control is provided with an actual pulley compensator 108b which calculates the external disturbance compensation from the actual pulley ratio (Aip) and a command value external disturbance compensator 108a which calculates the external disturbance compensation from the command pulley ratio. When switching from open loop control to feed back control, the actual pulley ratio compensator 108b is initialized to the actual variable ratio (Aip). On the other hand, the command value compensator 108a is initialized to the command pulley ratio (ip.sub.R).

Abstract: A speed ratio of a continuously variable transmission is varied according to an oil pressure which is adjusted by a valve driven by a step motor. The step motor is feedback controlled so that a real speed ratio coincides with a target speed ratio determined according to the running conditions of a vehicle. By determining a feedback gain based on the oil pressure, oil temperature, real speed ratio and output shaft rotation speed of the transmission, precise control of the speed ratio according to the running state is realized.

Abstract: A method for controlling the transmission ratio of a belt variator in a transmission unit for a motor vehicle is provided. The method at least provides for a control manner whereby the transmission ratio is controlled as a function of gear change signals given by a driver of the motor vehicle. The control is carried out according to what is called a variogram which is defined by a plurality of predetermined fixed control lines (A-B-C-D-E-F) via following the control lines. The control lines are determined so that, when gearing up and gearing down, respectively, large rotational speed differences in each successive transition between the control lines (A-B-C-D-E-F) are avoided.

Abstract: A system for controlling motive force of a vehicle having an engine and a continuously variable automatic transmission connected to the engine to transmit engine torque to a drive shaft of the vehicle. In the system, a desired motive force is calculated or determined from the detected accelerator (pedal) position and vehicle speed, and based on the determined motive force a desired engine speed, more specifically a drive shaft speed of the transmission, is calculated or determined. Then inertia torque acting on the vehicle is calculated or determined based on at least the determined speed and detected speed, and a desired throttle opening is corrected by the determined inertia torque when the vehicle accelerates or decelerates. With the arrangement, the vehicle response delay due to the inertia torque is adjusted and hence, drivability and fuel economy performance are enhanced.

Abstract: A shift control apparatus of a continuously variable transmission for a vehicle comprises sensors for detecting operating conditions of the transmission and a motor connected to the transmission. A controller of the shift control apparatus stores different shift maps and employs one of them according to a driver's command or vehicle driving condition. The controller decides a target value of an input rotation speed of the transmission from an output rotation speed of the transmission and the load condition of a motor on the basis of the shift map and continuously changes a gear ratio of the transmission so that the transmission input rotation speed is adjusted to the target value. The controller can change the rate of the shift speed according to a driver's command.

Abstract: A speed ratio controller for a continuously variable transmission of a vehicle is provided which sets a target speed ratio according to a vehicle speed and degree of accelerator pedal depression, sets a command speed ratio according to the target speed ratio and a predetermined dynamic characteristic, and controls the transmission so as to obtain the target speed ratio while a real speed ratio follows the command speed ratio. This speed ratio controller computes a deviation between the command speed ratio and target speed ratio, and determines whether an upshift characteristic is an auto upshift, foot release upshift or foot return upshift based on the speed ratio deviation, degree of accelerator pedal depression, and variation amount of the target input shaft rotation speed. The dynamic characteristic of the command speed ratio is set according to the determination result, and the response characteristics of the transmission are thereby modified.

Abstract: A continuously variable transmission control system determines the desired speed ratio for a continuously variable transmission from various input data received from the vehicle and operator. The desired speed ratio is compared with a commanded speed ratio to provide an error signal which establishes a new commanded speed ratio for the continuously variable transmission. The comparing process of desired speed ratio to commanded speed ratio is repeated until the error signal is substantially null. Also, the control provides an adaptive modifier for the actuator of the continuously variable transmission such that a comparison of actual transmission ratio to commanded speed ratio will determine if an adaptive modification is necessary. The control further provides a step control function which is operable when the ratio of the continuously variable transmission is moving toward an underdrive ratio.

Abstract: In apparatus and method for controlling a driving force for an automotive vehicle having an internal combustion engine, a slip condition of a driven road wheel is detected, an opening angle of an engine throttle valve so as to control the slip condition of the driven road wheel to a predetermined condition is adjusted, a target opening angle of the throttle valve according to the detected slip condition is derived, the opening angle of the throttle valve is determined, a steady state deviation of an output of the engine developed between the target opening angle of the throttle valve and the actually detected opening angle thereof is derived, and the derived steady state deviation is compensated using another driving force reducing control unit such as an engine control unit used for, for example, cutting off a fuel supply to a determined number of engine cylinders.

Abstract: A shift shock reducing apparatus installed in a vehicle which is equipped with a power train constituted by a continuously variable transmission (CVT) and an engine. The shift shock reducing apparatus comprises a calculating section which calculates an inertia torque caused by a shifting from a rate of change in a CVT ratio per time and an output torque correcting section which corrects a toque inputted to the CVT on the basis of the calculated inertia torque so as to cancel the inertia torque. Therefore, shift shocks due to the inertia torque is suppressed without generating a shift delay.

Abstract: A continuously variable transmission (CVT) has an increased speed of convergence on a neutral point by combining the rotation from the CVT and a constant velocity mechanism. At the neutral point the output member has zero rotation due to torque circulation. When a neutral state is determined to be needed based on the signals indicating the pulley ratio is within a predetermined range, with the throttle pedal being off or not depressed, and the brake pedal being on, the neutral control starts an operation to control the shaft force of both the primary and the secondary pulleys for the CVT. At the same time, the engine output is controlled by controlling the throttle opening degree and a predetermined torque is transmitted to the input shaft. As a result, the CVT converges on the gear neutral point (GN) at high speed due to an increase in the input torque of the CVT based on an increase in engine torque.

Abstract: A hydraulic emergency control for changing the hydraulic oil pressure in the hydraulic conical pulley axial adjustment mechanism of a continuously variable transmission (10) for varying the clamping force ratio has a pump (20) in an open hydraulic circuit that supplies the respective piston chambers (17, 13) of the secondary and primary axial adjustment mechanisms with hydraulic oil. The primary and secondary oil pressures are regulated by separate oil pressure limiting valves (30, 40). At least one throttle valve (51) is arranged between the pump (20) and the output pipe (92) of the open hydraulic circuit, at a point where the pump volumetric flow can be influenced. The hydraulic emergency control allows a starting transmission ratio to be set in a low range when starting the vehicle, whereas a very small reduction ratio is selected at a high driving speed and at light throttle.

Abstract: A continuously variable transmission control system employs a gear ratio control map which has a step-wise control zone of driving condition where engine speed is controlled to repeat alternate gradual increase and rapid decrease with an increase in vehicle speed so as thereby to vary step-wise a gear ratio and a continuous control zone of driving conditions where engine speed is controlled to increase approximately linearly with an increase in vehicle speed so as thereby to continuously vary a gear ratio, the step-wise control zone of driving condition based on which the gear ratio control is performed being narrowed when a driving condition is judged to be within a specified unstable zone.

Abstract: A device for controlling the gear ratio of a continuously variable transmission. The theoretical rotational speed or transmission ratio is fed to the signal input of a set-value filter (44). The time constant (T.sub.-- RS) of the set-value filter (44) is adaptively controlled so that the change in transmission ratio takes place in accordance with a transition function whose limit is defined by a maximum variation speed. The principal advantage of the invention is that the vehicle is not slowed when shifting down to lower transmission ratios.

Abstract: A hydraulic emergency control for a gear-ratio-dependent change in hydraulic fluid pressures in a first and second hydraulic bevel-gear axial adjuster of a continuously variable transmission (10), is provided in which a pump (1) supplies at least the piston chamber (17) of the second axial adjuster, and at least one downstream pressure limiting valve (40) limits the fluid pressure there and moreover from this supply, via a continuous path valve (20), supplies the piston chamber (13) of the first axial adjuster, and the continuous path valve (20) is controlled with the aid of a pressure differential acting on a throttle valve (39) that is downstream of the pump (1) and is integrated with a switching valve (30).

Abstract: A hydraulic emergency control system for a continuous looped gear type continuously variable transmission (10) includes first and second hydraulic beveled conical pulley axial actuators controlling a gear ratio. A pump supplies a first piston chamber (13) of said first axial actuator via a sensor valve (20), wherein the sensor valve (20) is controlled by a flow control valve (73) connected downstream of the pump (80). The pump (80) supplies a second piston chamber (17) of the second axial actuator, with a pressure relief valve (40) limiting fluid pressure in said second piston chamber. Fluid in the second piston chamber (17) is controlled as a function of the fluid pressure in the first piston chamber (13) via a control line (52, 113).

Abstract: In a controller which controls a speed change ratio of a continuously variable transmission to a target speed change ratio set based on the driving conditions of an automobile, the driver manually inputs a command which increases or decreases the speed change ratio. The controller increases or decreases the target speed change ratio by a predetermined amount according to this command. Preferably, this increase/decrease pattern is varied according to the time for which the command continues. The driver of the automobile can thereby achieve a desired speed change ratio by a simple operation.

Abstract: A control system of a vehicular continuously variable transmission having a manual transmission mode comprises speed ratio changing when a manual transmission mode is chosen and a speed range is manually selected for changing a speed ratio of the selected speed range in the up-shift direction as the engine speed becomes high on the side of low speed ranges and in the down-shift direction as the vehicle speed becomes high on the side of high speed ranges. Further, in the manual transmission mode, when the engine speed reaches a lower limit value without making a down-shift, the speed ratio is controlled so as to hold the engine speed at the lower limit value. Thus constituted continuously variable transmission provides a vehicle with miscellaneous advantages such as an easy handling, smooth acceleration/deceleration performance, extended maximum speed and the like when the manual transmission mode is selected.

Abstract: The invention relates to a continuously variable transmission. The continuously variable transmission according to the invention is designed such that in operating conditions to be defined in more detail the transmission ratio is kept essentially constant, in particular for travelling through bends, on inclines, in case of an emergency stop and during a transmission overspeeding. The constant transmission ratio is obtained while the input r.p.m. of the transmission is changing.

Abstract: In a continuously variable transmission (CVT) for a vehicle wherein a belt of V-shaped cross-section is looped around a drive pulley and a driven pulley respectively having grooves of identical shape to this belt, and the width of the groove of each pulley is varied according to a supplied oil pressure, an oil pressure when an accelerator pedal is released is maintained at or above a predetermined value. The oil pressure is controlled according to a torque input to the drive pulley, and the input torque varies according a depression amount of the accelerator pedal. As a result, the speed change ratio easily varies due to insufficient oil pressure when the accelerator pedal is released. This invention stops decline of oil pressure when the accelerator is released, and thereby prevents variation of the speed change ratio due to release of the accelerator pedal. This is especially useful when the speed change ratio of the transmission has been fixed by the driver in a manual speed change mode.

Abstract: The invention is directed to a system for automatically adjusting the gear ratio of a continuously variable transmission mounted next to the motor of a vehicle. The gear ratio is adjusted with a specific speed. The essence of the invention is that a mechanism is provided which facilitates a determination of the speed of the adjustment of the gear ratio of the transmission in dependence upon detected operating parameters. With the system of the invention, an adjustment characteristic of the transmission is obtained which is comfortable for the driver of the vehicle.

Abstract: A speed change ratio of a continuously variable transmission for converting the rotation of the output shaft of an engine in a stepless manner and transmitting it to a drive shaft of a vehicle is controlled to a target speed change ratio. A target vehicle speed at a predetermined future time is estimated based on a real vehicle speed, and the target speed change ratio is calculated based on the estimated vehicle speed. By controlling a real speed change ratio to this target speed change ratio, the response of the transmission is enhanced. Preferably, a feedback vehicle speed is calculated by processing the estimated vehicle speed with a predetermined lag element. By integrating a difference between the real vehicle speed and feedback speed so as to estimate the vehicle speed at the predetermined future time, hunting of the speed change ratio in the speed change ratio control is suppressed.

Abstract: A continuously variable V-belt transmission includes a lateral pressure control valve for controlling the lateral pressures of a drive pulley and a driven pulley, and a controller for controlling the lateral pressure control valve. The controller calculates a target belt transmission torque by adding a predetermined marginal torque to a transmission torque calculated based on a signal detected from a driving condition of a vehicle, and obtains, by means of a signal converter, a control signal for controlling the lateral pressure control valve. With this arrangement, it becomes possible to prevent slippage between the belt and pulleys and to produce a most appropriate clamping force even when the lateral pressure control oil pressure is varied due to secular and environmental changes in the pulley lateral pressure control valve, whereby the transmission is rendered durable, efficient in fuel consumption and highly reliable.

Abstract: A powertrain control method applied to a lean burn engine coupled to a continuously variable transmission for minimizing engine out emissions selects one or more control parameters from a plurality of parameters that may be precisely controlled to provide for acceptable powertrain control with minimized emissions. Lean burn engine operation is maintained under low brake mean effective pressure conditions by modulating powertrain output power through transmission drive ratio variation. Fuel and air per cylinder may further be varied with the drive ratio when low emissions can be provided with minimum sacrifice to fuel economy. Lean burn operation is suspended under high brake mean effective pressure conditions by driving air/fuel ratio toward the stoichiometric ratio to exploit the efficiency of an included three-way catalytic treatment device while lowering engine speed to stabilize combustion.

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: An external disturbance compensating output computing unit comprising a low pass filter is provided in a speed change controller of a continuously variable transmission. A real speed change ratio, and an actuator position signal or a speed change ratio command value are input to the external disturbance compensating output computing unit. The actuator position signal or speed change ratio command value of a speed change mechanism control unit are selectively assigned to a value input to the low pass filter according to a difference between the real speed change ratio and a target speed change ratio. When the difference between the real speed change ratio and target speed change ratio is small, non-linear characteristics of the speed change mechanism are compensated, and when the difference is large, the non-linear characteristics of the speed change mechanism are not compensated. In this way, a desired speed change response is obtained regardless of driving conditions.

Abstract: A method and apparatus for controlling a transmission for use with an automotive vehicle including an engine. The transmission coupled to the engine for transmitting a torque inputted thereto from the engine to produce an output torque at a continuously variable speed ratio. A target value for the speed ratio is calculated based on vehicle operating conditions. A rate at which the speed ratio changes to the calculated target value is calculated. An upper limit for the rate is calculated to satisfy such a condition that the transmission input torque is less than a maximum value below which there is no danger of damaging the transmission. The rate of change of the speed ratio is limited to the upper limit when the calculated rate of change of the speed ratio is greater than the upper limit.

Abstract: A method of controlling an electronically controlled, continuously variable transmission (3), according to which an electronic control device (15) determines a parameter K1 (24) on the basis of input variables, for example driving activity and topography. The parameter K1 (24) brings about a variation of an operating point.

Abstract: In a CVT transmission with planetary gear operation in forward, zero and reverse directions, reduction in CVT secondary/primary pulley ratio is inhibited when the pulley ratio is less than a set pulley ratio which is higher than the pulley ratio producing zero output rotation (a gear-neutral state). In a ratio region below the set pulley ratio, a movable sheave of a primary pulley is moved to an O/D side. The amount of the movement is detected by a sensor shoe (detecting means) which is associated with the movable sheave. A ratio sensing valve (inhibition means) associated with the sensor shoe, in turn, clogs a port, halting a hydraulic pressure supplied by a primary regulator valve. As a result, no hydraulic pressure is supplied to the second hydraulic chamber by way of a down-shift relief valve, a manual valve or a low-high control valve, inhibiting a down shift.

Abstract: A working fluid pressure control device for a hydraulic control system of a V-belt type continuously variable transmission comprises a line pressure regulator valve, a pressure reducer valve, a pressure modifier valve, in which the line pressure regulator valve developing a regulated line pressure for cylinder chambers of driving and driven pulleys of the transmission from a source pressure applied from a hydraulic pump driven by an engine associating with the transmission, the pressure reducer valve developing a reduced output pressure for a forward clutch and a reverse brake of the transmission from a source pressure supplied from the line pressure regulator valve, and the pressure modifier valve developing a pilot pressure for the line pressure regulator valve.

Abstract: An electronically controlled hydraulic apparatus for a belt drive type continuously variable transmission comprises a belt wound around a primary pulley and a secondary pulley, a line pressure control valve for controlling a line pressure of a secondary cylinder, a shift control valve for controlling a primary pressure of a primary cylinder. The shift control valve includes a pilot valve for generating a pilot pressure according to a solenoid current, a spool with a step and a valve body. The pilot pressure is applied to one end of the spool and the primary pressure feedbacked and a spring force are applied to the other end so as to control the primary pressure on the balance of the spool in the valve body. The step ratio of the spool is designed so as to be 1.11 to 1.5 and further the shift control valve is constituted such that the pilot pressure becomes near zero when the primary pressure is zero.

Abstract: By a controller which controls a speed-change control valve for switching a hydraulic pressure to be supplied to each of cylinder chambers of each of pulleys of a continuously variable vehicular transmission, the speed reduction ratio is controlled such that the engine revolution speed becomes a target revolution speed which is set depending on the running conditions of a vehicle. When an accumulated time of high-speed operation at which Ne becomes higher than a predetermined first set revolution speed exceeds a first set time, an upper limit value of Ne or the target revolution speed is corrected to decrease. Further, when the duration time of a low-speed revolution below a predetermined second set revolution speed which is smaller than the first set revolution speed exceeds a second set time, the upper limit value of Ne is corrected to increase or the correction to decrease the target revolution speed is stopped.