Abstract: A clutch (25, 26) which connects an engine to a toroidal continuously variable transmission (100) is engaged and transmits a torque to the transmission (100) according to a line pressure. The toroidal continuously variable transmission (100) transmits the torque also according to the line pressure. A microprocessor (81) calculates a first pressure required to engage the clutch (25, 26) in the idle running state of the engine (99), calculates a second pressure required for torque transmission of the clutch (25, 26) based on a torque transmission amount of the clutch (25, 26) (S141), and calculates a third pressure required for torque transmission of the continuously variable transmission (100) based on the torque transmission amount of the clutch (25, 26) and the speed ratio of the continuously variable transmission (100) (S142).

Abstract: An automatic transmission includes a transmission case containing oil, a transmission structure housed in the transmission case, for varying the ratio of rotational speeds between a driving shaft connected to wheels and an engine shaft connected to an engine, a transmission control valve housed in the transmission case, for controlling the transmission structure, and a motor as a driving source for driving the transmission control valve. The motor includes a cover, a motor body having a coil disposed under the cover and formed with a wound conductor, a shaft rotated by an electrical current applied to the coil, and a converting structure for converting the rotational movement of the shaft into linear movement. The motor is fixed to the transmission case so that the motor body is disposed in air.

Abstract: The present invention provides a line pressure control device for a continuous transmission in an automotive vehicle, wherein a life of a belt is capable of being lengthened by avoiding a slip of the belt under any running conditions.

Abstract: When a slip control system starts operating, a vehicle speed VSP used for speed change control is simultaneously changed over from a sensor detected vehicle speed VSPSEN to an estimated vehicle speed VSPFL. On the other hand, when the slip control system has stopped, it is first determined whether a speed ratio variation amount, due to the change-over of the vehicle speed used for speed change control from the estimated vehicle speed VSPFL to the sensor detected vehicle speed VSPSEN, is less than a permissible amount. When it is determined that the speed ratio variation amount is smaller than the permissible amount, the vehicle speed used for speed change control is changed over from the estimated vehicle speed VSPFL to the sensor detected vehicle speed VSPSEN. By performing this change-over, a sharp variation of the vehicle speed used for speed change control is suppressed, and a sharp variation of the speed ratio leading to shocks or slipping is suppressed.

Abstract: An adjustable pulley for use in a continuous variable transmission in the power train of a motor vehicle has an axially fixed first conical flange and an axially movable second conical flange. The hydraulic control system which moves the second flange relative to the first flange is provided with at least one first plenum chamber which receives pressurized fluid when the second flange is to move toward the first flange, and with an additional plenum chamber which receives pressurized fluid when the second flange is to move away from the first flange. The admission of pressurized fluid into the additional chamber is regulated in dependency upon the RPM of the flanges. Rapid evacuation of pressurized fluid from the additional chamber can take place by way of a relief valve which opens when the pressure of fluid in the additional chamber rises to a preselected value. This renders it possible to rapidly shift between overdrive and underdrive.

Abstract: A motor vehicle has a continuously variable transmission and a hydraulic device to perform the functions of changing as well as maintaining the ratio of the continuously variable transmission. The hydraulic device comprises a valve arrangement with at least one connector terminal for controlling a transmission ratio change and at least one connector terminal for maintaining the transmission ratio at a set level.

Abstract: Leak oil from a regulator 24 for regulating the pressure of oil supplied to a lubricating system (the lubricating pressure) is supplied to an oil cooler 23. An electromagnetic valve 25 is connected to a pressure controlling and regulating oil chamber 24a of the regulator 24 so that the lubricating pressure can be controlled to be increased or decreased. The lubricating pressure is decreased while an engine is running in a low load state during a high-speed running to thereby increase the volume of oil to be supplied to the oil cooler 23.

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 system for pressure control of a variator (7) of an automatic transmission having an electronic transmission control is connected with a lubricant circuit (10) in which at least one lubrication valve (14) and one radiator (13) are situated. Oil is fed to the hydraulic system with the lubricant circuit (10), from an oil source (4). At the same time, a hydraulic emergency device is provided which has at least one emergency valve (29) to provide a constant pressure ratio between a primary pulley set (19) and a secondary pulley set (20) of the variator (7). In addition, the system has for reducing the thermal load in the emergency operation at least one device (35, 37, 43, 45, 46, 51) by means of which in emergency operation the oil flow through the radiator (13) is increased and the pressure on one output side of the radiator (13) is reduced.

Abstract: A shift control system for a continuously variable transmission which has target gear ratio corresponding value calculating means for calculating a target gear ratio corresponding value of the continuously variable transmission according to at least a throttle opening, and shift control means for controlling a gear ratio of said continuously variable transmission so that the target gear ratio corresponding value can be obtained, comprises reactive force applying means disposed on an accelerator pedal and applying a reactive force, which increases according to an increase of the accelerator pedal opening, to a pedal depression force of a driver in a large accelerator pedal opening range.

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: A line pressure control device for a continuously variable transmission comprises: a target line pressure setting part that sets a target value of a line pressure, which is able to adjust a clamping force applied to a transmission member of the continuously variable transmission; and an engine torque suppressing part that suppresses an engine torque to prevent the transmission member from slipping. When it is impossible to suppress the engine torque and thus a torque non-suppressible flag is set, the target value of the line pressure is corrected to a greater value to prevent the transmission member from slipping. Otherwise, the target value of the line pressure is set to a smaller value. This makes it possible to surely prevent the transmission member from slipping.

Abstract: An apparatus and a method control a continuously variable transmission of a motor vehicle which includes a power transmitting member for power transmission by use of friction. A controller of the apparatus detects slippage of the power transmitting member in a predetermined period of running of the vehicle, and increases a clamping pressure that is applied to the power transmitting member when slippage of the power transmitting member is detected. The controller also stores a state of increase of the clamping pressure in a memory, and increases the clamping pressure applied to the power transmitting member in accordance with a previous state of increase of the clamping pressure that was stored in the memory in a previous period of operation of the vehicle.

Abstract: When the temperature of operating fluid of an actuator is low, a target input rotation speed lower limit value NinL is set. The lower limit value NinL is greater than a lower limit value set for a normal temperature of operating fluid. A target input rotation speed Nint is calculated from the state of running of a vehicle, such as the amount of operation of an accelerator, the vehicle speed, etc. If the target input rotation speed is lower than the lower limit value NinL, the target input rotation speed is reset to the lower limit value NinL. As a result of a control that includes the above-described steps, the speed ratio &ggr; becomes relatively high before the vehicle stops. Therefore, even if the speed ratio-changing rate is low, the speed ratio &ggr; can be brought to or near a maximum value &ggr;max before the vehicle stops. Thus, reductions in the speed ratio-changing rate caused by low temperature of the operating fluid of the actuator can be curbed.

Abstract: Hydraulic pressure generated by an oil pump driven by an engine is regulated to a secondary pressure by means of a secondary pressure control valve. The secondary pressure is employed for controlling a secondary pulley and a primary pulley. On the other hand, the secondary pressure is reduced to a clutch pressure by means of a clutch pressure control valve. The communication between an apply chamber and a release chamber of a torque converter, oil chambers of actuators for a forward clutch and a reverse brake of a forward and reverse changeover apparatus and a clutch pressure line and a lubrication pressure line are controlled by means a switching valve. The clutch pressure is regulated to a high clutch pressure and to a low clutch pressure, respectively by controlling reverse signal pressures supplied to these outer pilot chambers.

Abstract: A system for control of a CVT driven by a drive unit has an electromagnetically controlled pressure-control valve which actuates both a main pressure valve and a secondary valve for the secondary pulley wherein geometry and spring tension of a main pressure valve and the secondary valve provide different characteristic lines.

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 transmission mechanism of the continuously variable transmission comprises a set of primary and secondary pulleys between which a belt is provided. The CVT control unit is operable to supply line pressure directly to a secondary pulley and also to a primary pulley via a shift control valve associated with a step motor in such a manner as to control a transmission ratio. The CVT control unit calculates a standard step position of the step motor corresponding to the target transmission ratio and provides a command signal representative of a difference between the standard step position and the current position of the step motor. The shift control valve actuated by the step motor controls the pressure to be supplied to the primary pulley. The actual transmission ratio obtained on the basis of the rotation speeds of the pulleys is compared with the target transmission ratio. If the shift is not accomplished, the CVT control unit commands additional step number.

Abstract: The invention proceeds from a control of a transmission which is adjustable continuously with respect to its transmission ratio, for a motor vehicle. The transmission together with a drive unit is mounted in the drive train of the motor vehicle and the drive unit has an adjustable drive torque. The transmission includes a drive end as well as an output end and operative means for establishing a mechanical operative connection between the drive end and the output end. Furthermore, detection means for detecting a slip quantity is provided. The slip quantity represents the slip between the operating means and the drive end and/or output end. Pregivable measures are initiated in response to a pregiven value of the slip quantity. The essence of the invention is that measures as follows are initiated: a drive of a clutch mounted in the drive train; and/or, a change of the transmission ratio; and/or, a change of the output torque of the drive unit.

Abstract: An electronic transmission control system for an automotive vehicle with a belt-type continuously variable automatic transmission comprises a transmission ratio control device including a first motor-driven oil pump supplying working pressure directly to a secondary pulley actuation chamber, and a second motor-driven oil pump supplying working pressure directly to a primary pulley actuation chamber and enabling working oil to come and go between the primary and secondary pulley actuation chambers therethrough. A first control section is provided for controlling the first motor-driven oil pump so that the actual secondary pulley pressure is adjusted to a target working pressure needed to hold a belt capacity of a drive belt, which belt capacity is defined as a capacity required for exerting a grip of the drive belt on primary and secondary pulleys.

Abstract: The method for monitoring a continuously variable transmission (CVT) with a variator for adjustment of the speed ratio, which has its primary and secondary adjustment devices respectively controlled by a pressure-regulating valve, consists of a travel monitoring and/or pressure monitoring of the pressure-regulating valves wherein in case of detection of an incorrect operation the power-flow transmitting clutch is opened.

Abstract: A continuously variable transmission of an automobile which varies the drive ratio arbitrarily between an input axis and an output axis is combined with a traction control device for example which performs braking corresponding to vehicle running conditions and irrespective of the accelerator pedal depression. A microprocessor calculates the vehicle speed from the rotation speed of the output axis, calculates the target drive ratio depending on the vehicle speed, and controls the drive ratio of the continuously variable transmission to be equal to the target ratio. When the brake operation device performs braking, fluctuation of the drive ratio based on the rotation variation of the output axis is prevented by the correction of the drive ratio in the upshift direction.

Abstract: An electronic transmission control system for an automotive vehicle with a belt-type continuously variable automatic transmission comprises a transmission ratio control device including a first motor-driven oil pump supplying working pressure directly to a secondary pulley actuation chamber, and a second motor-driven oil pump supplying working pressure directly to a primary pulley actuation chamber and enabling working oil to come and go between the primary and secondary pulley actuation chambers therethrough. A first control section is provided for controlling the first motor-driven oil pump with feed-forward compensation for the working pressure supplied to the secondary pulley actuation chamber, based on changes in a flow rate of the working oil coming and going between the primary and secondary pulley actuation chambers, so that the secondary pulley pressure is regulated as a belt capacity holding pressure needed to hold a belt capacity of the drive belt in a first motor-driven pump side.

Abstract: A control system controls a line pressure applied to a CVT upon taking account of a certrifugal pressure caused by a rotation of pulleys. The control system determines whether the centrifugal pressure is greater than a predeterminied value only by which the pulley transmits an input torque from an engine. When the determination is affirmative, a lower limit of a duty ratio for operating a line pressure control valve is switched from a lower limit of a linear range to 0% duty ratio. Therefore, an actual transmissiou ratio control range is expanded while preventing an undershoot of the line pressure.

Abstract: The invention proceeds from a control of a transmission, which is continuously adjustable with respect to its transmission ratio, for a motor vehicle wherein the transmission together with a drive unit is mounted in the drive train of the motor vehicle. The drive unit has an adjustable output torque. According to the invention, determination means for determining a quantity is provided which represents the instantaneous maximum transmittable torque of the transmission. Furthermore, the output torque of the drive unit is limited to a limit value by limiting means. This limit value is determined in dependence upon the above-determined quantity. In order to reliably protect the transmission against damage by increased slippage, it is therefore provided according to the invention to limit the torque outputted by the engine when the contact force is so small that the danger of slippage exists. The torque of the motor can, in general, be more rapidly limited than the contact force can be increased.

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: In a disengagement side control, in a power on state, a disengagement side pressure P.sub.W is output, P.sub.W being set higher than a base pressure dependent on input torque, and a disengagement side frictional engagement element is engaged and maintained. In a power off state, a disengagement side pressure lower than the base pressure is output, and the disengagement side frictional engagement element slips. In the disengagement side control, when the vehicle driving state is changed from the power off state to the power on state, the disengagement side pressure P.sub.W is changed from that for a slip state to that for a maintain state.

Abstract: A pressure reducing valve and a continuously variable transmission comprising an output pressure feedback loop operatively connected to provide proportional control of an output pressure of a flow of fluid passing through the pressure reducing valve in response to an input signal applied to a pilot stage control valve of the pressure reducing valve from an external source. The pressure reducing valve includes a main stage two-way spool valve having a valve body and a valve spool movable within the valve body in response to an imbalance of forces on the valve spool. The valve body has a supply port for receiving pressurized fluid from a source of constant hydraulic pressure and a load port for communicating a load pressure and flow from the spool valve to an actuator of the secondary pulley of the transmission to maintain transmission belt tension while preventing or minimizing belt slippage. The open area of the load port is dependent on the position of the valve spool within the valve body.

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: The present invention is a control device and a control method for a transmission with a clutch, by which the clutch is smoothly coupled without generation of shocks or the like in a vehicle.

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: 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: For a CVT it is proposed to determine an operating point from the number of revolutions of the primary disc (12) and the number of revolutions of the secondary disc (13). The operating point is assigned to a first characteristic field which has ranges of unauthorized ratios and one range of authorized ratio. If an error occurs, the pressure level in the adjustment area of the secondary disc (pSEK) is increased in a first step. If the error continues an emergency program is activated in a second step.

Abstract: For achieving a high accuracy line pressure control and a high line pressure, a valve control system outputs a first signal pressure to a primary regulator valve as a second signal pressure when the first signal pressure is low. The valve control system outputs a gain pressure higher than the first signal pressure to the primary regulator valve as the second signal pressure when the first signal pressure is high. A change amount of the line pressure from the primary regulator valve concerning with a change amount of the first signal pressure is a gain. The gain is a low gain which increases the accuracy of the line pressure control when the first signal pressure is low, and the gain is a high gain with which the high line pressure is output when the first signal pressure is high.

Abstract: A control system for a CVT comprises a controller arranged to compute an engine revolution condition on the basis of an engine revolution speed indicative signal, to compute actual and estimated engine outputs on the basis of the engine revolution condition, to compute a rotational change condition of the drive system, to compute an actual input load change amount caused by the inertia by multiplying the actual rotational change condition detection value by a predetermined inertial constant, to compute an estimated input load change amount by multiplying the estimated rotational change condition detection value by a predetermined inertia coefficient, to select larger one of the actual input load change amount and the estimated input load change amount as the input load change amount for outputting a command signal, and to output the command signal to a line pressure duty valve on the basis of the engine output and the selected input load change amount so as to further accurately control a line pressure.

Abstract: An apparatus for controlling a dynamic system, for example, a continuously variable transmission for an automotive vehicle which adjusts a gear ratio by bringing a pulley position of a primary pulley into agreement with a target one through a hydraulic system under the feedforward and sliding mode control is provided. The apparatus calculates a feedforward-controlled variable in addition to a feedback-controlled variable and adjusts the pulley position of the primary pulley to a target one using the hydraulic pressure provided based on the sum of the feedforward-controlled variable and the feedback-controlled variable, thereby enhancing the robustness of the sliding mode control without causing the hunting.

Abstract: A method for regulating a belt variator type transmission unit for motor vehicles, and which includes a belt variator, a reversing unit and a hydraulically controlled engine drive coupling that controls the reversing unit to provide forward and reverse drive connection between the engine and variator. The drive coupling comprises a forward coupling and a reverse coupling including fluid driven clutches which may be operated via a pressure regulating unit that provides an adjustable clutch actuating pressure. The clutch actuating pressure is hydraulically regulated both as a function of engine Pitot pressure which is representative of the engine speed, and as a function of a regulated pressure which is set by an electronically controlled valve.

Abstract: For a CVT (3) a regulating system is proposed in which a corrector is located upstream of the control path. The disturbances and non-linearities in the control path (28) are taken into account in the corrector, via a mathematical model, so that the regulator can be designed as a simple PID regulator.

Abstract: The up-shift is discriminated to be in any one of a first up-shift mode in which the throttle opening degree remains nearly constant, a second up-shift mode accompanying the operation for nearly fully closing the throttle or a third up-shift mode accompanying the operation for closing the throttle to a half opened state. On the other hand, the down-shift is discriminated to be either in a first down-shift mode which accompanies the operation for opening the throttle or in a second down-shift mode accompanying the decrease in the vehicle speed. The rate of changing the speed is set for each of the speed change modes, and the speed change ratio of the continuously variable transmission is so controlled that the actual speed change ratio is gradually brought to the basic speed change ratio based upon said rate of changing the speed.

Abstract: In a pulley working fluid (oil) passage arrangement for a belt-type continuously variable transmission having a V belt wound about a letter V-shaped groove formed with mutually opposing oblique surfaces of movable and stationary sheaves and a working fluid pressure cylinder chamber to which a working fluid pressure is supplied so as to move the movable sheave toward or away from the stationary sheave, thus a gear shift being varied, a first working fluid passage communicated with an axle chamber working fluid passage is extended in an axial direction of the axle member at an opposing surface thereof against the axle member and the movable sheave and a second working fluid passage having one end communicated with the first working fluid passage and the other end opened to a working fluid pressure cylinder chamber is extended along a radial direction of the axle member.

Abstract: A work vehicle having an improved transmission control circuit, that is responsive to a shuttle shift lever and associated switch that generates a forward signal, a reverse signal and a neutral signal, whereby the transmission control circuit engages the transmission in a forward gear ratio on receipt of the forward signal, a reverse gear ratio on receipt of the reverse signal and places the transmission in neutral on receipt of the neutral signal, and further wherein the transmission control circuit further places the transmission in neutral whenever it receives both a forward and neutral signal, or both a reverse and neutral signal.

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 output torque is substantially equal to or greater than zero. 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 fluid is guided inside a spool in which an orifice and drain holes are formed. The spool is displaced according to a hydraulic fluid pressure difference across the orifice. An outflow port, which is always connected with the orifice, and a drain passage, which overlaps with the drain holes according to a displacement position of the spool, are formed in the casing housing the spool. A stopper that limits the spool displacement beyond a position at which the overlap between the drain holes and drain passage is maximized is further provided. In this way, drainage of a fluid via the drain holes and drain passage is maintained at a maximum level even when fluid flows into the spool at a flow rate exceeding a predetermined level, and sharp increases of fluid flow rate from the orifice are thereby suppressed. By limiting excessive displacement of the spool, hysteresis is also prevented from occurring in the flow rate characteristics.

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: 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 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 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 rotation ratio of a continuously variable transmission for a vehicle provided with a pair of variable pulleys whereof the diameter of a contact part with a V-belt is made to vary according to an oil pressure, is controlled according to the running state of a vehicle. An oil pressure control valve is therefore provided to control the oil pressure. A rotation ratio command value is computed from a target rotation ratio set according to the vehicle running state and a control variable set for each rotation ratio according to the dynamic characteristics of the transmission. By inputting a signal based on this rotation ratio command value to the oil pressure control valve, a desirable speed change response is obtained.