Abstract: A displacement-actuated positive-drive clutch (10; 20) includes an input member (11; 21) having a positive engagement structure (11d; 21d) provided thereon and an output member (13; 23). A clutch plate (16; 25) is connected for rotation with and for axial movement relative to the output member (13; 23). The clutch plate (16; 25) has a positive engagement structure (16b; 25b) provided thereon that positively engages the positive engagement structure (11d; 21d) provided on the input member (11; 21) to engage the displacement-actuated positive-drive clutch automatically in response to the occurrence of a predetermined amount of relative rotational movement between the input member (11; 21) and the output member (13; 23).

Abstract: An apparatus configured for controlling starting of engine may include a clutch pedal including an ignition lock switch, a starter, a status detecting unit, an electronic clutch mounted between the engine and a transmission, a clutch controller configured to control coupling and releasing of the electronic clutch, check status of the electronic clutch and generate a clutch status data, and a vehicle controller configured to enter coasting running mode based on the vehicle status data, and, during the coasting running mode, operate the starter and restart the engine based on the clutch status data provided from the clutch controller and a switch status data of the ignition lock switch when a position value of an acceleration pedal included in the vehicle status data is equal to or greater than an acceleration reference value.

Abstract: A crank permission system includes first and second permission modules and a crank module. The first permission module selectively generates a first permission signal, based on a first gear range engaged within a transmission, when an ignition system transitions to crank. The second permission module selectively generates a second permission signal, based on (i) the first gear range stored when the ignition system last transitioned to off and (ii) a second gear range of the transmission requested by a driver using a transmission range selector, when the ignition system transitions to crank. The crank module begins cranking an engine via a starter, in response to the generation of at least one of the first and second permission signals, when the ignition system of the vehicle transitions to crank.

Abstract: A coupling comprises a pair of clutch end members, a clutch center member disposed between the clutch end members, and an actuator coupled to one of the end members. Each end member includes concentric V-grooves disposed on a respective face thereof. The center member is axially movable between the end members, and includes a pair of opposing surfaces. One of the opposing surfaces includes concentric V-grooves configured to mesh with the V-grooves of one of the end members. Another of the opposing surfaces includes concentric V-grooves configured to mesh with the V-grooves of another of the end members. The actuator is configured to simultaneously couple the end members to the center member by urging the V-grooves of both of the end members into engagement with the V-grooves of the center member.

Abstract: A twin clutch controlling apparatus includes a clutch actuator for controlling a twin clutch TCL, and a manual operation clutch capacity arithmetic operation section for converting an operation amount of a clutch lever L into an electric signal to arithmetically operate a manual operation clutch capacity arithmetic operation value (tqc1tmt) corresponding to the manual operation. The twin clutch controlling apparatus is configured so as to accept a changeover from an Auto mode to a Temp mode in response to an operation of the clutch lever L. When an operation of the clutch lever L is detected during automatic control in the Auto mode, an event that the manual operation clutch capacity arithmetic operation value (tqc1tmt) comes to have a value similar to that of the clutch capacity (tqc1at) calculated in the Auto mode is included in conditions for a changeover to the Temp mode to occur.

Abstract: A twin clutch controlling apparatus includes an ATM control unit for controlling a shift actuator and a clutch actuator and a shift pedal P for carrying out shifting request to the ATM control unit. When a shifting request by the shift pedal P is issued, the ATM control unit drives the shift actuator to change over the shift stage to a next stage gear irrespective of an operational amount of a clutch lever L and then causes the manual operation clutch capacity arithmetic operation value (tqcltmt) to correspond to a clutch capacity corresponding to the next stage gear using an operational amount of the clutch lever L that exceeds a predetermined value as a trigger. If a predetermined period of time elapses while the clutch lever L is not operated, then the shifting request is an erroneous operation and the shift stage is returned to an original gear.

Abstract: A rotational assembly hub can include a sprocket that is configured to rotate about an axis, where the sprocket can be located on a first side of a driver. Moveable paws can be located on a second side of the driver that is opposite the first side of the driver. The moveable paws can be configured to move from a recessed position within the driver to a protruding position when the driver rotates in a first direction in a first rotational mode and can be configured to remain protruding from the recessed position when rotated in the first direction in a second rotational mode. Other assemblies are also disclosed.

Abstract: A dual clutch automated manual transmission includes a first clutch and a second clutch, and a clutch torque capacity command value for a plurality of clutch actuators arranged to drive the first clutch and second clutch based on operation of a by-wire type of clutch lever, wherein the clutch torque capacity of the plurality of clutches is controlled. An operator can adjust a driving force by manually operating the clutch in the transmission in which a clutch operation is controlled automatically, such as an automatic transmission system, automated manual transmission system, or dual clutch automated manual transmission system, thereby improving drivability.

Abstract: In a method for influencing the traction force during shifting operations of a manual transmission in vehicles having at least two drive axles, the drive system of the first axle is activated in such a way that the interruptions in traction force occurring at the second axle during shifting operations of the manual transmission are at least partially compensated for.

Abstract: This invention describes two types of mechanical clutches; a selectable one-way clutch and a two-way or dog clutch. Both clutches are constructed with sprags mounted on an axis that is tilted with respect to the axis of the shafts being connected by the clutches. Both engagement faces of the clutch are conical and parallel such that the clutches can be disengaged by withdrawing one of the clutch plates along the line of the shafts being connected. Sprags produce a one-way clutch. In the dog clutch, alternate sprags are mounted opposite to its neighbor, so the clutch is prevented from slipping in either direction.

Abstract: In a multiple disc clutch apparatus 10, a cam member 41 which is disposed on a side of a clutch inner member 16 is formed into an annular shape. The cam member 41 extends in a radial direction so that an outer circumferential surface of the cam member 41 is brought into abutment with a cylindrical face 19d on an inner circumferential surface of a clutch center member 19.

Abstract: A controllable transmission system and a method thereof are provided. The controllable transmission system includes a first rotation device, a coupling device and a control device. The first rotation device includes a transmission shaft, a rotation body and a plurality of blade units connected with the rotation body, wherein each of the blade units includes an adjustable blade having a first and a second contact elements and having an opening corresponding to the adjustable blade. The coupling device is mounted beside the rotation device and includes a coupling unit having a first and a second contact surfaces. The control device is connected with the coupling device for controlling a movement of the coupling device to cause one of the contact surfaces positioned corresponding to a respective one of the first contact element and the second contact element.

Abstract: A lens barrel includes a distance adjustment ring for moving a movable lens group; a hand-operated ring and a motor for rotating the distance adjustment ring; a one-way rotational transfer mechanism which transfers torque of the hand-operated ring to the distance adjustment ring when the hand-operated ring is manually rotated, and prevents torque of the distance adjustment ring transferring to the hand-operated ring when the distance adjustment ring is rotated by the motor. A circumferentially-uneven-width-space forming portion formed on an annular overlapping portion of the hand-operated ring, is shaped so that a torque transfer member, installed in an accommodation space between the annular overlapping portion and-a torque transfer cylindrical surface on the distance adjustment ring, wedges between the circumferentially-uneven-width-space forming portion and the torque transfer cylindrical surface to transfer the torque of the manually rotated hand-operated ring to the distance adjustment ring.

Abstract: A bi-directional clutch for operating a window dressing such as a roller shade includes a protective guard for securing the window dressing to a stationary structure, a gear box for transmitting rotation to an output member in response to the operation of an elongated operating member such as a cord, and an antirotational member that prevents the undesirable operation of the output member. The output member is coupled to the window dressing. The gear box includes a gear pulley coupled to the elongated operating member, a planetary gear and a stationary gear. The gear box is arranged and constructed to transmit motion to the output member in response to the activation of the elongated operating member, at a predetermined mechanical advantage.

Abstract: The present invention provides a method and apparatus for controlling the pressure of an actuating fluid flowing through an inching clutch. The invention includes the steps of determining an actual pressure of the actuating fluid, establishing an inching pressure threshold, comparing the actual pressure with the threshold, and controlling the actual pressure in response to the comparison. In one embodiment, the pressure is controlled using a first control algorithm in response to the fluid pressure being less than an inching threshold, and using a second control algorithm in response to the pressure being greater than or equal to the inching threshold.

Abstract: A control system for a motor vehicle drive includes an engine control configuration for controlling a variable influencing torque of an engine. A transmission control configuration controls shifting operations of an automatic transmission with a torque converter and transmits an intervention signal to the engine control configuration to carry out an intended shifting operation in a jerk-free and low-wear manner. The transmission control configuration has a circuit configuration for determining a fraction by which the engine torque is to be changed for the shifting operation. The fraction is determined as a function of a transmission input torque obtained from a converter amplification determined by the transmission control configuration and the engine torque determined by the engine control configuration, and as a function of the type of shift. The fraction is transmitted to the engine control configuration as control information for altering the engine torque.

Abstract: A method of preventing a wheel loader from slipping, aiming at reducing the amount of slip of the loader during excavating operation using it, and preventing the decline in operational efficiency due to the slip. The method of preventing a wheel loader from slipping comprises the steps of detecting the occurrence of slip in accordance with the difference in the number of revolutions between a pair of left and right drive wheels and the change thereof, and controlling the clutch pressure so that the clutch is put in half-clutch condition upon detection of the occurrence of slip.

Abstract: A vehicle transmission system having shift levers mechanically linked to couplers for selection of ranges of gear speed ratios and electro-hydraulic powershift clutches for selection of a gear speed ratio within the selected range is provided with controls for avoiding unexpected speeds or speed changes under certain conditions. If the vehicle is moving at start-up as a result of a stall or accidental reset of the microprocessor, and the shift levers have not been moved since the stall or reset, the microprocessor retrieves from a nonvolatile memory an indication of the last selected powershift gear prior to the reset and uses it for the initial powershift gear selection. When an operator depresses a clutch, shifts a shift lever and then changes his mind and shifts the shift lever back to its original position before releasing the clutch above a threshold point, the microprocessor selects the powershift gear in effect at the time the clutch pedal was depressed.

Abstract: A transmission controller is provided for use with a vehicle having a transmission including a plurality of gears, a hydraulic pressure controlled clutch, and a solenoid-actuated proportional valve for operating the clutch. The controller comprises a signal generating circuit for generating a controlled current signal for operating the solenoid-actuated proportional valve and a current monitoring circuit for producing a current signal corresponding to the current flow to each of the solenoid-actuated proportional valves. A vehicle monitor produces a threshold signal corresponding to a predetermined point at which the clutch begins to carry torque and a memory retains predetermined information corresponding to the current signals.

Abstract: A torque converter lockup clutch control apparatus operates a lockup clutch to provide a controlled degree of slip between the converter cover and the turbine hub. Cylinder output sensors are provided for monitoring outputs produced in the respective cylinders of an internal combustion engine. The monitored cuylinder outputs are utilized to calculate the amplitude of fluctuation of the torque outputted from the engine. The degree of slip provided in the lockup clutch is changed when the calculated amplitude exceeds a predetermined value.

Abstract: The system provides an improved clutch control system for use in a continuously variable transmission system. The system provides for generation of a clutch pressure setpoint to re-engage the clutch during special conditions in which the torque created by the vehicle inertia would tend to drive the engine to an undesirable operating point. Clutch slip speed is monitored as a difference value and integrated to provide a gradually decreasing error signal to return the clutch input speed to the clutch output speed, at which time clutch lockup will occur. Additionally, throttle position is monitored and a maximum torque schedule used to provide a maximum torque signal to prevent driver demand from undesirably racing the engine in similar conditions. A filtered output of the maximum torque schedule provides a pressure setpoint signal representative of actual driver demand which may be added to the clutch slip speed error signal to generate the clutch pressure setpoint.

Abstract: An electronically controlled automatic transmission system for applying and releasing clutches and brakes when the gears for the speed ranges are to be shifted or changed in accordance with the drive torque of the engine. Each brake and clutch is controlled by a solenoid valve and a manual valve. The manual valves control the application of fluid pressure to the clutches and the brakes. Each manual valve has a separate solenoid valve which controls the manual valve in accordance with the detected value of the driving force of the engine. In addition, the automatic transmission system measures the number of revolutions of the input shaft to the automatic transmission after the clutches and brakes at the release side are released for a gear shift, and detects the acceleration of the number of revolutions of the input shaft of the automatic transmission.

Abstract: In a process for regulating a clutch which is situated within a power train between an input shaft (22) and an output shaft (24), the rotation-rate differences .DELTA..omega. of the power train are detected via a sensor device. With the use of regulating equipment and depending on a control variable x, a correcting variable y which affects the speed difference .DELTA.n is controlled. To provide regulating equipment at favorable construction cost, the regulating equipment has a comparator unit (51) in which an actual value x of the rotation-rate difference .DELTA..omega. in the power train behind the clutch (21) is compared with a preset fixed limited value w.sub.const, the rotation-rate difference .DELTA..omega. being limited to the limit value w.sub.const by changing the correcting variable of the clutch (21) upon reaching or exceeding the limit value w.sub.const.

Abstract: The operation of an automated friction clutch between the output element of the engine and the input element of the variable-speed transmission in a motor vehicle is regulated by a fluid-operated system which receives signals from an evaluating circuit. The evaluating circuit receives signals from a number of sensors which monitor the RPM of the engine, the RPM of the input element of the transmission, clutch travel, the position of the throttle valve, the position of the shift linkage, the position of the gas pedal and other parameters. The fluid-operated system can select the condition of the clutch during starting, driving, acceleration, parking, driving in reverse and/or parking of the motor vehicle and/or during transitions between such stages of operation.

Abstract: A method of controlling a friction type clutch of a vehicle having an engine and a drive train, which clutch is operated by hydraulic oil and is frictionally engageable to transfer rotational driving force from an output shaft of the engine to the drive train, includes the steps of causing the clutch to assume a slipping state of engagement upon starting of the vehicle, and defining a first amount of time as a function of the temperature of the hydrauilc oil. When the first amount of time has elapsed since the starting of the vehicle, the clutch is positively urged from slipping state of engagement into a locked up state of engagement.

Abstract: An IC engine is connected via a clutch with a change-speed transmission. A sensor responding to a gear selection informs the electronic control circuitry in which gear the vehicle is traveling. The rotary part of a tachometer is provided at the output of the transmission and is in cooperation with the sensor part of the tachometer, which feeds a signal to the electronic control circuitry. A universal joint shaft runs from the output of the transmission to the axle transmission, which is connected via the axles to the drive wheels. The rotary tachometer elements, connected with the drive wheels, are in cooperation with the tachometer sensors, whose output signals are supplied to the electronic control circuitry and compared therein with a calibration value. Such comparison determines the optimum clutch engagement time for the respective travel and loading condition of the vehicle.

Abstract: In a powertrain including an engine controlled by the position of the throttle valve, a hydrodynamic torque converter and multiple ratio automatic transmission connected to the drive wheels of the vehicle, a solenoid-operated hydraulic valve supplies pressurized fluid to engage and release the clutch that controls torque transfer between an offgoing clutch and an oncoming clutch. The position of the throttle valve and the speed of the engine are applied as input to a mathematical model programmed in algorithmic form for execution by a digital microprocessor. The engine produces a signal representing net torque output by the engine and torque converter, which signal is applied as input to an inverse mathematical model of the solenoid-operated valve that supplies hydraulic fluid to the controlling clutch. The unique relationship of phase to gain, the frequency response of the solenoid valve, is inverted within the frequency range of interest to remove the effects of delay.

Abstract: An electronically controlled automatic transmission system including an automatic transmission having a plurality of clutches and brakes activated by application of a fluid pressure to change the gear ratio by engagement and disengagement of the clutches and brakes, a fluid pressure switching device for controlling the application of the fluid pressure to the clutches and brakes, and an electronic controller for changing the engagement and disengagement of the clutches and brakes by driving the fluid pressure switching device in accordance with the running condition of the vehicle, the electronic controller also controlling the speed of engagement of a clutch or brake which is to be engaged. The electronic controller includes a torque sensor for detecting the torque of the output shaft of the automatic transmission, and an engagement speed correcting device for correcting the speed of engagement of a clutch or brake which is to be engaged on the basis of the detected torque.

Abstract: A slip control system for a torque converter of an automatic transmission includes lock-up clutch device provided in a torque converter for connecting an input and output members of the torque converter directly. A torque detecting device detects a transmitted torque introduced into the output member of the torque converter, a speed difference setting device sets a target value of a rotation speed difference between the input and output members, a pressure difference control device controls a pressure difference between a releasing chamber and an engaging chamber of the lock-up clutch device, based on a predetermined relationship between the input torque and the speed difference so as to accomplish the target value of the speed difference, and a speed difference detecting device detects an actual speed difference between the input and output members.

Abstract: A vehicle transmission control arrangement in which an automatic clutch is disengaged in response to a signal received from a shift lever switch provided to detect an operation of a shift lever for shifting a speed changing mechanism. A comparator is provided to determine whether a detected or determined output torque of an engine is smaller than a predetermined reference value below which an increase in the engine speed upon full disengagement of the clutch will not significantly deteriorate a driving comfort of the vehicle. A clutch control device is adapted to inhibit the clutch from being fully disengaged despite the presence of the signal from the shift lever switch, if the engine output torque is not smaller than the reference value.

Abstract: A torque converter with a lockup clutch is interposed between an engine and a driven wheel, and the lockup clutch is coupled or uncoupled on the basis of a predetermined lockup characteristic. When a slip value of the driven wheel against a road surface reaches a given value or higher, torque to be applied to the driven wheel is decreased to thereby perform slip control. During this slip control, the lockup clutch is forced to be uncoupled prior to the lockup characteristic. The forcibly uncoupled state of the lockup clutch is maintained for a given period of time from the time when the slip control ends.

Abstract: A control strategy for obtaining optimal acceleration of a vehicle containing a dual range infinitely variable transmission. The transmission output clutch is selectively engaged in order to provide an optimal distribution of power during acceleration of a vehicle between accelerating the vehicle and accelerating the engine speed in order to obtain a higher power output from the engine.

Abstract: A lock-up clutch control system for an automatic power transmission includes a torque converter mode, a full lock-up mode and a clip lock-up mode for controlling operation of a lock-up clutch which is disposed between a pump impeller and a turbine runner of a torque converter. The slip lock-up mode is a transitional mode between the torque converter mode and the full lock-up mode and connects the pump impeller and the turbine runner such that a relative rotation therebetween is allowed. In the system, one of the above-noted three modes is selected based on preselected vehicular operating condition indicative parameters, such as, an engine load and a vehicle speed. When a rapid depression of an accelerator pedal by a driver is detected after the slip lock-up mode is selected, the torque converter mode is executed in place of the slip lock-up mode until the rapid depression of the accelerator pedal is not detected.

Abstract: A control apparatus for an automatic clutch device which comprises a primary pressure controlling valve for controlling a primary pressure in an oil clutch, a line pressure controlling valve for controlling a line pressure in the oil clutch, a clutch pressure controlling valve for controlling a clutch pressure in the oil clutch, first, second and third electromagnetic valves for controlling respectively the primary pressure controlling valve, the line pressure controlling valve and the clutch pressure controlling valve, and a control section which controls the first, second and third electromagnetic valves and effects a feed-back control of engine speed to the third electromagnetic valve, and which stores values obtained by the learning of feedback quantities of the engine speed until the last time and changes a clutch pressure control duty to the third electromagnetic valve by modifying a feed forward quantity with the value by learning.

Abstract: A transmission controller is provided for use with a vehicle having a transmission including a plurality of gears, a hydraulic pressure controlled clutch, and a solenoid-actuated proportional valve for operating the clutch. The controller comprises a signal generating circuit for generating a controlled current signal for operating the solenoid-actuated proportional valve and a current monitoring circuit for producing a current signal corresponding to the current flow to each of the solenoid-actuated proportional valves. A vehicle monitor produces a threshold signal corresponding to a predetermined point at which the clutch begins to carry torque and a memory retains predetermined information corresponding to the current signals.

Abstract: For controlling a motor vehicle friction clutch (3) which is operated by an actuating drive (7) during parking maneuvers, an output adjusting device (19) of the internal combustion engine (1) is unaffected over a limited initial pedal travel (.alpha..sub.0) of the accelerator pedal (17). According to the pedal position at any given time, the actuating drive (7) of the clutch (3) is controlled within the initial pedal travel. According to the pedal position and in keeping with a predetermined first signal characteristic a desired torque signal is generated and the actuating drive (7) is positioned as a function of the desired torque signal and in keeping with a predetermined second signal characteristic. In the clutch position determined by the pedal position, an actual torque signal is generated which represents the torque of the internal combustion engine (1) and it is compared with the desired torque signal.

Abstract: An adaptive control system controls the slip across a start clutch located up-stream of a continuously variable transmission to allow the clutch to be use as a torsional isolator in a continuously variable transmission. The system includes a torsional vibration detector for determining the actual level of torsional vibrations transmitted by the clutch. The actual level of vibrations is compared with an acceptable level and the slip across the clutch is regulated in order to maintain the transmission of vibrations to the acceptable level.

Abstract: A method of controlling the rotational speed of a continuously variable transmission having a pair of pulleys which each includes a fixed pulley member and a movable pulley member, including the steps of decreasing and increasing the groove width between each pair of fixed and movable pulley members to respectively increase and decrease the rotational radius of a belt wrapped around the pulleys. A hydraulic clutch is provided and is connected to and disconnected from the driving force of the transmission in response to clutch pressure applied thereto. A control section is provided for calculating a desired clutch pressure for the hydraulic clutch. This desired clutch pressure is based on an engine torque value and a desired engine rotational speed. When the clutch is in a normal starting mode and certain other predetermined conditions are satisfied, the control section is used to adjust the desired engine rotational speed based on the temperature of the oil in the transmission.

Abstract: In a control system for controlling a clutch coupled with an internal combustion engine for driving a vehicle off, the control operation for clutch engagement is carried out based on the level of power insufficiency of the engine. When the level of engine insufficiency is within a predetermined range, the operation for clutch engagement is controlled in accordance with the change in the amount of operation of an accelerating member without stopping the engaging operation of the clutch. In order to improve the performance experienced by the operator at drive-off, just after recovery from power insufficiency, the target clutch stroke to be followed is corrected by correction data determined on the basis of the difference between the target and actual clutch stroke at the time the engine has just recovered from its power insufficiency.

Abstract: A device for controlling an automatic motor vehicle clutch is arranged between a driving enging and a transmission. This clutch operates primarily as a starting clutch and the engine torque TM and the rotational speeds before and after the clutch nM, nGE are detected or measured. A control device transforms an electric signal coming from an electronic control unit into a control value for the regulating device for the opening and closing of the clutch from the frequency and the amplitude of the engine speed and/or the transmission input speed, unacceptable vibrations (S) in the drive train betweeen the engine, clutch and transmission are detected and eliminated through a predetermined opening of the clutch. This opening takes place up to a path mark which is derived from a characteristic curve stored in an electronic control unit.

Abstract: In a work vehicle including a hydraulic clutch for a transmission system, the invention discloses an art of quickly yet shocklessly controlling the engagement of the clutch by properly judging a preliminary oil pressure condition and a half-clutched condition through a detection of torque developed in the transmission system.

Abstract: A control system for a vehicle drive train includes a controller which is responsive to a throttle signal from a throttle position sensor and which controls a clutch unit to control speed and acceleration and to obtain optimum driver "feel". The system is responsive to advancing movement of a throttle to a more open position to efficiently utilize rotating energy of engine parts for more rapid vehicle acceleration.

Abstract: A slip control system of a lock-up clutch of an automatic transmission comprising a torque converter, lock-up clutch, slip control device for controlling an engaging force of the lock-up clutch to establish a slip control in which a predetermined rotation speed difference is allowed between the input member and output member when a vehicle operating condition is in a predetermined slip control zone, transient control device for carrying out a transient control by setting a transient control factor to increase a change in the engaging force of the lock-up clutch for a transient condition when the vehicle operating condition is transferred from a non-slip control zone to the slip control zone, and the transient control factor being determined in accordance with a vehicle operating condition just before the vehicle operating condition falls into the slip control zone.

Abstract: A feedback control system and method for controlling the wheel slip of a wheel driven by torque coupled through an electronically controlled hydraulically operable clutch from an internal combustion engine. A first feedback variable related to wheel slip and a second feedback variable related to hydraulic pressure applied to the clutch are summed to generate a feedback control signal. In response to the feedback control signal, the clutch is slipped by regulating the hydraulic pressure to reduce the driven wheel speed. Engine speed is adjusted in response to a measurement of driven wheel speed to prevent over-revving of the engine and maintain a desired predetermined positive torque on the driven wheel while the clutch is being slipped.

Abstract: In engine torque control in a motor vehicle having an engine and a stepping type of transmission, input and output speeds of the transmission are constantly detected by sensors disposed in input and output portions of the transmission, thereby obtaining a gear ratio (measured value) of the transmission. If the ratio of the difference between this gear ratio and a predetermined gear ratio before the gearshift (theoretical value) to the latter gear ratio before the gearshift exceeds a predetermined value, the start of gearshift is decided. If the ratio of the difference between the gear ratio of the transmission (measured value) and a predetermined gear ratio after the gearshift (theoretical value) to the latter gear ratio after the gearshift becomes smaller than a predetermined value, the end of gearshift is decided.

Abstract: A control system for an electromagnetic clutch for a vehicle has an engine speed sensor, a clutch driven member speed sensor and a throttle position sensor. The system has a memory storing first torque capacities increasing with increase of engine speed and storing second torque capacities at clutch engagement rate 100% in accordance with engine speed and throttle position. The actual clutch engagement rate is calculated based on output signals of the engine speed sensor and the clutch driven member speed sensor. A first torque capacity and a second capacity are derived from the memory in accordance with output signals of the sensors. A torque capacity Tc for engaging the clutch is calculated as follows,Tc=Re.multidot.TcL+(1-Re).multidot.Tcswhere Re is the clutch engagement rate, Tcs is the first torque capacity and TcL is the second torque capacity.

Abstract: A system for controlling a drag torque of an electromagnetic clutch at idling operation of an engine for a motor vehicle with a continuously variable belt drive transmission. A detector is provided for detecting whether engine speed is higher or lower than a predetermined minimum idling speed. When the engine speed is at a higher engine speed, a standard current is passed in a coil of the clutch. At a lower idling speed, the drag current is gradually reduced until the engine speed increases to the predetermined minimum idling speed.

Abstract: A system for controlling a drag torque of an electromagnetic clutch at releasing of an accelerator pedal of a motor vehicle with a continuously variable belt drive transmission. A detector is provided for detecting whether vehicle speed is lower than a predetermined low speed. At the low vehicle speed, the drag current is gradually reduced as the vehicle speed increases.

Abstract: A system for controlling an electromagnetic clutch for a motor vehicle at starting of the motor vehicle. An actual engagement rate is obtained in dependency on speeds of a drive member and a driven member of the clutch. A desired output-input speed ratio of the clutch is obtained in accordance with load on the engine and the speed of the driven member, the output-input speed ratio representing a decreasing function of the engine load and an increasing function of the speed of the driven member. Clutch current is controlled so as to converge the actual output-input speed ratio to the desired engagement rate, thereby smoothly engaging the clutch at the start of the vehicle.

Abstract: A method and an apparatus of controlling an electromagnetic clutch incorporated in a power transmission system of a vehicle to transmit an output of an engine to the drive wheels of the vehicle is disclosed. An amount of electric current applied to the clutch is regulated to control an engaging action of said electromagnetic clutch, based on either a variation in rotating speed or torque of an output shaft of the electromagnetic clutch, or based on the frequency or number of variations per unit time in rotating speed or torque of the output shaft, as compared with the frequency or number of ignitions or combustions per unit time of the engine. In this way a variation in output torque of the engine is absorbed by the electromagnetic clutch for improved drivability, while a transmission power loss in the clutch is kept to a minimum for maximum fuel economy.