Mazda Motor Corporation

Tomoo Sawasaki

Chitoshi Morishige

Keiji Bota

Yuji Mori

Syuichi Kawamura

Shuichi Kawamura

Takashi Nogami

Masako Kagawa

A control apparatus for controlling a stepless transmission which changes the effective diameter between a primary pulley and a secondary pulley by cyclically controlling a change rate toward a target value to be set in advance based upon the characteristic set in advance. The apparatus detects the throttle opening degree TVO, a RANGE signal, the revolutional frequency of the secondary pulley Ns and the like, and detects whether the vehicle is in a transitional status of an acceleration operation or a deceleration operation. At a point in time during the transitional period, the apparatus sets a first target value based upon the signals such as the TVO signal, the RANGE signal and the Ns signal, and sets a second target value based upon the difference between the first target value set in the current control cycle and the second target value set in the previous control cycle, at the same time, sets a change in the second target value to be smaller than that in the first target value. The change rate is controlled toward this second target value.

Control apparatus for stepless transmission for vehicles

An automatic transmission system having a belt type infinitely variable gear is housed in a transmission casing. The transmission casing is formed of a torque convertor housing portion in which the torque convertor is housed and an infinitely variable gear housing portion in which the infinitely variable gear is housed. A forward-reverse switching mechanism is provided between the torque convertor and the primary shaft of the infinitely variable gear and is supported on the torque convertor housing portion. Opposite ends of the primary shaft of the infinitely variable gear are supported on support portions respectively formed on the infinitely variable gear housing portion and the torque convertor housing portion, and opposite ends of the secondary shaft of the infinitely variable gear are supported on support portions respectively formed on the infinitely variable gear housing portion and the torque convertor housing portion.

Automatic transmission system for vehicle

A hydraulic control apparatus for a transmission performs hydraulic control for the pressure controlling valves by conducting a feedback pressure control on one pressure controlling valve provided in the transmission on the basis of the output of a hydraulic sensor and by performing feedforward control on the other pressure controlling valve in the transmission utilizing the results of the feedback control.

Hydraulic control apparatus for hydraulic transmission

A control apparatus for a transmission apparatus which controls the change ratio by varying, by hydraulic pressure, the effective radius of a drive pulley (primary pulley) and that of a follower pulley (secondary pulley) with a belt arranged therebetween. The apparatus a change ratio control valve for controlling the change ratio and a change ratio fixing valve for forcibly fixing the change ratio if the engine is about to rotate excessively so that the excessive rotation of the engine is prevented.

Control apparatus for stepless transmission

A hydraulic control system for a steplessly variable transmission, having primary and secondary pulley assemblies, controls a line pressure for complementarily varying effective diameters of the primary and secondary pulley assemblies so as to steplessly vary a transmission ratio of the steplessly variable transmission. The line pressure is changed according to an engine output transmitted to the primary pulley assembly from an engine and a transmission ratio of the steplessly variable transmission. A decrease of pressure is caused in the line pressure according to a thrust exerted on either one of the primary and secondary pulley assemblies caused by centrifugal force.

Hydraulic transmission control system

A steplessly variable power transmission has a torque converter provided with an input member connected with an engine output member of an engine and an output member. A belt-pulley type of steplessly variable power transmitting mechanism is provided with primary pulley device, connected with the output member of the torque converter. A secondary pulley device, constituting an output member of the transmission, is also provided and a belt connects the primary pulley devices with the secondary pulley device for transmitting power between the primary and secondary pulley device with a predetermined pulley speed ratio. A hydraulic control system controls effetive diameters of the primary and secondary pulley devices to thereby change the speed ratio of the transmission steplessly. An output torque of the torque converter or a turbine torque of the torque converter, and the pulley speed ratio are calculated. A line pressure of the hydraulic control system is controlled in accordance with signals representing the output or turbine torque and pulley speed ratio to control the effective diameter so that a slippage of the belt can be effectively prevented.

Hydraulic control system for steplessly variable transmission

A control system for a steplessly variable transmission comprising a drive pulley and driven pulley formed with V-shaped grooves respectively, an endless belt engaged with the both grooves of the pulleys and tensioned between the pulleys to transmit engine torque therethrough, cylinders provided on the pulleys for being subjected to a hydraulic pressure to vary an effective diameter of the pulleys so that a speed ratio of the transmission is continuously changed, a hydraulic pressure supply device for introducing the hydraulic pressure into the cylinder means, a line pressure control device for controlling a line pressure of a hydraulic circuit which controls operation of the cylinders, a line pressure detecting device for detecting the line pressure, a torque detecting device for detecting the engine torque transmitted to the drive pulley, a torque allowance computing device for computing a maximum allowable belt transmitting torque which is effectively transmitted from the drive pulley to the driven pulley through the belt under the line pressure detected by the line pressure detecting device, and the torque control device for controlling a torque transmitted from the drive pulley to the driven pulley to a value smaller than the maximum torque when the engine torque detected by the torque detecting device is greater than the maximum torque. When a line pressure of a hydraulic control circuit therefor is unduly lowered, the slip between the drive and driven pulleys can be effectively suppressed.

Control system for steplessly variable power transmission

A hydraulic control system for controlling a transmission of an automotive vehicle has a hydraulic pump driven by an engine to deliver a line pressure and a regulator valve for regulating the line pressure according to a pilot pressure applied thereto. To change the pilot pressure so as to regulate the line pressure to a desired pressure, a duty solenoid valve is operated at a proper duty rate with a steady signal. The steady signal for operating the duty solenoid valve at the desired duty rate is provided at a frequency which is changed according to operating conditions of the automotive vehicle.

A hydraulic control system for a steplessly variable power transmission includes primary and secondary pulleys, a belt connected with both pulleys and, hydraulic chambers for controlling effective diameters of the pulleys for changing a speed ratio steplessly. A speed ratio control valve controls the hydraulic pressure applied to the hydraulic chamber in accordance with a pilot pressure introduced into a pilot chamber provided in the speed ratio control valve means. A solenoid valve controls the pilot pressure applied to the speed ratio control valve, and a fluid pressure producing device produces a control pressure in accordance with a vehicle driving condition. A switch valve selectively connects the pilot chamber with either the solenoid valve or the fluid pressure producing device. The switch valve is actuated so as to connect the pilot chamber with the fluid pressure producing device when a deviation between an actual pilot pressure and a desirable pilot pressure is increased beyond a predetermined value. A stable speed ratio control therefore can be provided.

Hydraulic control system for steplessly variable power transmission

A hydraulic control system for an automatic transmission including a pressure regulating valve responsive to a pilot pressure to produce a regulated line pressure which is applied through a switching valve to an actuator of a clutch. The switching valve is also responsive to the pilot pressure to allow the pilot pressure to be introduced to the actuator when the pilot pressure is below the predetermined value and passes the line pressure to the actuator when the pilot pressure is above the predetermined value.

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Hiroshima, Japan

Tomoo Sawasaki