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: A belt-type continuously variable transmission has a pulley side pressure control valve for controlling side pressures of driving and driven pulleys and a controller for controlling the pulley side pressure control valve. The controller has a correcting device for correcting a belt transmission torque calculated by a belt transmission torque calculator when the polarity of the belt transmission torque changes. The correcting device adds to the belt transmission torque for a predetermined time a correction value corresponding to a peak torque of the belt transmission torque arising at times of throttle opening and closing. That is, because the belt transmission torque is corrected in correspondence with the peak torque arising at times of throttle opening and closing, the side pressures of the pulleys are kept at suitable values at all times and slippage of the metal V-belt is prevented.

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 method and apparatus for controlling a continuously variable transmission having an input and output shaft for use with an automotive vehicle. The transmission is operable at a variable speed ratio for transmitting a drive from the input shaft to the output shaft. A target value for the speed of rotation of the input shaft of the transmission is calculated based on the sensed vehicle operating conditions including vehicle acceleration (deceleration). A correction factor per predetermined unit time is calculated based on the vehicle acceleration (deceleration) when the vehicle acceleration (deceleration) exceeds a threshold value with the accelerator pedal being released. The correction factor is used to correct the target input shaft speed value at intervals of the predetermined unit time. The speed ratio is controlled to bring the input shaft speed into coincidence with the corrected target value.

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: In order to optimize the speed change control of a continuously variable transmission, a necessary minimum primary pressure (Ppmin) for achieving a target speed change ratio is computed, and also a necessary minimum line pressure (Plmin) for the non occurrence of slippage between a secondary pulley 5 and a belt 6 is computed, and a required speed change ratio line pressure (Plratio) which can realize a target speed change ratio without slippage on the primary pulley 4 side is computed. The highest of these is then selected. The selected line pressure (Pl base) is then corrected by a transition line pressure (Pl add) determined from engine torque (TQ.sub.ENG) and speed change speed (SV), to obtain a final output line pressure (Plprs) which is then used to control a secondary pulley actuator 5a. In this way, speed change control can be optimized, for example by controlling slipping of the belt 6 at the time of rapid speed change.

Abstract: In order to optimize the speed change control of a continuously variable transmission, a necessary minimum primary pressure (Ppmin) for achieving speed change ratio control, a necessary minimum line pressure (Plmin) for the non occurrence of slippage between a secondary pulley 3 and a belt 4, and a required speed change ratio line pressure (Plratio) which can realize a target speed change ratio without slippage on the primary pulley 2 side are computed. The highest of these is then selected, and a final output line pressure (Plprs) then obtained based on the selected line pressure. By using this line pressure (Plprs) to control a secondary pulley actuator 3a, slipping of the belt 4 can be prevented and a target speed change ratio achieved, with an extremely simple construction compared to that of conventional arrangements.

Abstract: A CVT control system for a vehicle drivetrain controls line pressure applied to an output pulley of the CVT to different levels against various CVT ratios in response to operator brake command, causing the output pulley to create force to hold the V-belt.

Abstract: In a control apparatus for controlling a gear shift ratio of a continuously variable transmission mounted in an automotive vehicle as an automatic power transmission, a gear shift ratio command value is calculated using a control constant corresponding to a dynamic characteristic determined for each instantaneous gear shift ratio of the continuously variable transmission so as to achieve a target gear shift ratio response characteristic.

Abstract: A continuously variable transmission system includes a belt type continuously variable transmission unit (CVT) wherein the direction of torque transmission is switched by torque circulation between a low mode and a high mode accompanied by a change in the axial forces on the pulleys of the CVT. In the Low mode of the D range, a comparatively high hydraulic pressure from a regulator valve is supplied to a Low clutch hydraulic servo via a low-high shifting valve and to a secondary hydraulic servo. In addition, a comparatively low hydraulic pressure from a ratio control valve is supplied to a primary hydraulic servo. These oil pressure feeds are reversed by the switching of the low-high shifting valve.

Abstract: A clutch operational control apparatus (75) controls an engaging force of a starting clutch (5) which is provided in a power transmitting path including an automatic transmission (CVT). The control apparatus comprises an idling state detector of an engine, a vacuum pressure detector for detecting an actual intake vacuum pressure of the engine, a range judging unit for judging a shift position of a manual shift lever, a target intake vacuum pressure determining unit for determining a target intake vacuum pressure, and clutch engaging force control means for controlling the clutch engaging force. The target intake vacuum pressure determining unit determines the target intake vacuum pressure based on the actual intake vacuum pressure when it is judged that the shift position is in the non-driving range and further when it is detected that said engine is in the idling state.

Abstract: A pulley thrust pressure control apparatus for a belt-type continuously variable transmission having a drive pulley connected with an input member, a driven pulley connected with an output member, a V-belt trained around the drive and driven pulleys, a drive cylinder for varying the pulley width of the drive pulley, and a driven cylinder for varying the pulley width of the driven pulley. The actual transmitting torque transmitted through the V-belt is calculated and a belt transmittable torque is calculated by multiplying the actual transmitting torque by a safety factor which is higher when said actual transmitting torque is negative than when it is positive. A pulley thrust pressure control valve controls the pressures supplied to the drive and driven cylinders so as to obtain the calculated belt transmitting torque.

Abstract: An automatic transmission of a vehicle including a speed change gear mechanism including rotary members such as gears and gear carriers and hydraulically operated friction engaging means and adapted to provide various speed stages according to selective engagement and disengagement of the friction engaging means is controlled by such steps as detecting rotation speed of at least one of the rotary members during a shifting between the speed stages, changing hydraulic pressure of at least one of the friction engaging means during a first phase of the speed stage shifting so as to make the rotation speed of the one rotary member follow a first change performance curve calculated according to a first feedback control program, and changing the hydraulic pressure of the one friction engaging means during a second phase of the speed stage shifting so as to make the rotation speed of the one rotary member follow a second change performance curve calculated according to a second feedback control program in continuity

Abstract: A device for optically providing information pertaining to the value of the quotient of the rates of revolution of two axles contains converters connected to the axles, which converters generate electrical signals which are a measure for the rate of revolution of the respective axles. At least one of the signals is fed to a ladder network of resistances which contains tap-off points which are connected to similar inputs of comparator circuits. The other inputs of the various amplifiers receive as input the signal which is a measure for the rate of revolution of the other axle. The comparator circuits are each coupled to light-emitting elements of which a few, depending upon the quotient of the revolution rates, illuminate. When applied in a vehicle which is provided with a continuously variable transmission, optical information pertaining to the current value of the transmission ratio is thus provided.