Abstract: A system for controlling a power transmission of a four-wheel drive vehicle powered by an engine has a transmission for transmitting the power of the engine to main driving wheels of the four-wheel drive vehicle, a hydraulically operated clutch for transmitting the power to auxiliary driving wheels, a hydraulic circuit for operating the clutch in accordance with driving conditions. The system comprises a sensor for detecting the inclination of roads and for producing an output signal dependent on the inclination, and a control circuit responsive to the output signal from the sensor for engaging the clutch when the output signal exceeds a predetermined value, thereby establishing the four-wheel drive.

Abstract: A system for controlling power transmission of a four-wheel drive vehicle powered by an engine. The vehicle is provided with a transmission for transmitting a power of the engine to main wheels and a clutch for selectively transmitting the power to auxiliary wheels. In order to detect sudden braking of the vehicle, a vehicle speed sensor and a control circuit for detecting deceleration of the vehicle greater than a predetermined value are provided, the control circuit producing an output signal. A switch is provided responsive to the output signal for engaging the clutch, whereby the four-wheel driving power transmission is established.

Abstract: A system for controlling an electromagnetic clutch for a vehicle, the system has a pulse generating circuit responsive to ignition pulses for an engine for producing pulses, an accelerator switch for sensing the depression of an accelerator pedal of the engine and for producing a first signal.An accelerator position switch is provided for sensing a deep depression of the accelerator pedal and for producing a second signal, and an accelerator pedal switch failure detecting circuit is provided to respond to the inverted signal of the first signal and to the second signal for producing a third signal which is applied to a gate circuit for opening it to pass the pulses thereby enabling the start of the vehicle, even if the accelerator switch is out of order.

Abstract: A system for controlling a power transmission of a four-wheel drive vehicle powered by an engine has a transmission for transmitting the power of the engine to main driving wheels of the four-wheel drive vehicle, and a clutch for transmitting the power to auxiliary driving wheels. A hydraulic circuit and a solenoid operated valve are provided for operating the clutch.First sensors are provided for detecting the speed of the main and auxiliary driving wheels, respectively, and second sensors are provided for detecting depression of an accelerator pedal and depression of a brake pedal of the vehicle respectively. When a large difference between the speed of the wheels is detected, the clutch is engaged, and when a large acceleration and large deceleration dependent on the output of the first sensors are detected, the clutch is engaged for establishing the four-wheel drive.

Abstract: A system for controlling a power transmission of a four-wheel drive vehicle powered by an engine. The system is provided with a transmission for transmitting a power of the engine to main wheels, a clutch for selectively transmitting the power to auxiliary wheels, a vehicle speed sensor for sensing the speed of the vehicle and for producing a vehicle speed signal dependent on the speed, a steering angle sensor for sensing the steering angle of the vehicle and for producing a steering angle signal dependent on the steering angle. A control circuit is provided to compare the vehicle speed signal and steering angle signal with reference values and judge whether the condition is in the range of conditions causing tight corner braking and to produce a clutch signal. A switch is responsive to the clutch signal for disengaging the clutch, whereby the four-wheel drive is changed to the two-wheel drive.

Abstract: A system for a four-wheel drive vehicle for automatically changing a power transmission system of an engine of the vehicle from two-wheel driving to four-wheel driving in accordance with driving conditions. The transmission system is provided for transmitting power from the engine to two main driving wheels, and a clutch is provided for transmitting the power of the engine to auxiliary driving wheels. Speed sensors are provided for producing output signals dependent on the speeds of the main and auxiliary wheels, respectively. A load sensor for sensing the load on the engine is provided. A first computing circuit is provided for producing a slip speed signal from output signals of the speed sensors, and a second computing circuit is provided for producing a reference value dependent on the output of the load sensor and a proportional constant which is a value in relationship between the slip speed and the load on the engine.

Abstract: A system for a four-wheel drive vehicle for automatically changing a power transmission system of the engine of the vehicle from two-wheel driving to four-wheel driving in accordance with driving conditions. The transmission system transmits power from the engine to main wheels, and a clutch is provided for transmitting the power of the engine to auxiliary wheels. A speed sensor is provided for producing output signals dependent on speed of the main wheels. A first computing circuit is provided for producing a vehicle speed signal from the output signals of the speed sensor, and a second computing circuit is provided for producing an angular acceleration signal from the output signals of the speed sensor. A comparing circuit is provided for comparing the angular acceleration signal and a reference value with each other and for producing an output signal when the angular acceleration signal is higher than the reference value. The reference value is decreased as the vehicle speed increases.

Abstract: A system for controlling stall speed for an electromagnetic clutch having a magnetizing coil for engaging a crankshaft of an internal combustion engine with an input shaft of a transmission of a vehicle. A transistor switching circuit for allowing clutch current to flow through the magnetizing coil, and an electric circuit for producing pulses dependent on ignition pulses of the engine are provided for intermittently turning on the transistor for energizing the coil. A circuit including a time constant circuit and a switching transistor is provided for decreasing duty ratio of the pulses and for decreasing the clutch current. Switches are provided for detecting a heavy load condition at starting of the vehicle and for producing an output signal. The output signal is latched by a flip-flop and applied to the switching transistor thereby to decrease the duty ratio of the pulses for decreasing the clutch current with respect to the engine speed.

Abstract: A control system for a belt-drive continuously variable transmission. The transmission is connected to a crankshaft of an engine through an electromagnetic powder clutch. The control system has a vacuum switch which is closed by rapid release of an accelerator pedal for producing engine braking effect, a gate circuit including a NOR gate, and an astable multivibrator. The NOR gate is opened for a short time decided by a time constant circuit, and the multivibrator supplies pulses through the NOR gate to a switching transistor provided in a circuit of the electromagnetic clutch for periodically opening the transistor during the opening of the NOR gate. Thus, the electromagnetic clutch is intermittently engaged for providing partial engagement of the clutch for the short time.

Abstract: A system for regulating the idle speed of an internal combustion engine. The engine has an alternator, and a voltage regulator having a Darlington circuit connected between an end of a field winding of the alternator and the ground. The Darlington circuit is responsive to the output voltage of the alternator for controlling the current flowing a field winding of the alternator so as to regulate the output voltage of the alternator. The system has an integrator for integrating the voltage across the Darlington circuit and a comparator for comparing the output voltage of the integrator with a reference voltage and for producing an output voltage dependent on the comparison.A solenoid is operatively connected to a throttle valve of the engine.A switching transistor circuit is provided to respond to the output voltage of the comparator for allowing the current to pass through the solenoid and for actuating the throttle valve to regulate the idle speed.

Abstract: A system for controlling an electromagnetic clutch of an internal combustion engine mounted on a vehicle, the clutch having a drive member secured to a crankshaft of the internal combustion engine, a driven member adjacent the drive member, and a magnetizing coil provided in one of said members, and a transmission secured to the driven member. A pulse generating circuit is provided for producing output pulses in dependency on the speed of the engine. An idling speed detecting circuit and a correcting circuit are provided for producing a correcting output when the idling engine speed increases which is caused when the choke valve or the air conditioning device of the vehicle is operated. Gate means is responsive to the output of the pulse generating circuit for producing an output which is applied to a switching transistor. The transistor is turned on by the output, so that clutch current passes through the magnetizing coil for engaging the clutch.

Abstract: A system for controlling an electro-magnetic clutch of an internal combustion engine mounted on a car which is capable of controlling the clutch current after the gear-changing for providing the partial engagement of the clutch. The electro-magnetic clutch has a drive member secured to a crankshaft of the internal combustion engine, a driven member adjacent the drive member, which is coupled to a transmission of the car and a magnetizing coil provided in one of the members. A shift lever signal is provided during the operation of the shift lever of the transmission and an acceleration signal is provided according to the operation of the accelerator pedal of the car. A control circuit comprises a charging circuit operated by the shift lever signal, a standard voltage circuit responsive to the acceleration signal, and a comparator connected to the charging circuit and standard voltage circuit for producing an output signal for a period of time which is decided by the level of the acceleration signal.

Abstract: A system for controlling an electro-magnetic clutch of an internal combustion engine mounted on a vehicle, which is capable of eliminating residual magnetism during operation of a shift lever of a transmission. The electro-magnetic clutch has a drive member secured to a crankshaft of the internal combustion engine, a magnetizing coil provided in the drive member and a driven member adjacent said drive member. A neutral switch is provided for detecting when the shift lever is in a neutral position and a shift lever switch is provided for producing a signal during operation of the shift lever for the transmission. Both signals of the neutral switch and the shift lever switch are fed to a control circuit. The control circuit is so arranged that the current flowing through the magnetizing coil is inverted in dependency on the output signals of the neutral switch and shift lever switch, so that the residual magnetism in the clutch may be eliminated.

Abstract: A system for controlling an electro-magnetic clutch of an internal combustion engine mounted on a car, which has a drive member secured to a crankshaft of the internal combustion engine, a magnetizing coil provided in the drive member, a driven member adjacent the drive member, and a transmission secured to the driven member. An engine speed detecting circuit is provided for producing an output when the engine speed exceeds a predetermined speed in an accelerating condition, the output signal being retained until the engine speed falls below a speed different from the predetermined speed. A gate is responsive to the output of the engine speed detecting circuit for producing an output which is applied to a switching transistor. The transistor is turned on by the output, so that a rated current passes through the magnetizing coil for engaging the clutch.

Abstract: A system for controlling an electromagnetic clutch of an internal combustion engine mounted on a vehicle, which has a magnetizing coil and a transmission. A vehicle speed detecting circuit is provided for producing an output when the vehicle speed exceeds a predetermined speed and another detecting circuit for a vehicle travelling condition is provided for producing an output by signals from a top-gear switch provided in the transmission and from an engine speed switch. A trouble detecting circuit is provided for producing a trouble signal when the output of the speed detecting circuit is not applied in spite of the output of the vehicle travelling condition detecting circuit. A gate device is responsive to the trouble signal for producing an output which is applied to a switching transistor. The transistor is turned on by the output, so that clutch current passes through the magnetizing coil for engaging the circuit.

Abstract: A system for controlling an electromagnetic clutch of an internal combustion engine mounted on a vehicle, which is capable of eliminating the residual magnetism during operation of a shift lever of a transmission. The electromagnetic clutch has a drive member secured to a crankshaft of the internal combustion engine, a driven member adjacent the drive member, and a magnetizing coil provided in one of the members. A neutral switch is provided for detecting when the shift lever is in a neutral position and a switch for detecting acceleration is provided for producing a signal when the engine is not accelerated. Both signals of the switches are fed to a control circuit. The control circuit is so arranged that the current flowing through the magnetizing coil is inverted in dependency on the output signals, so that the residual magnetism in the clutch may be eliminated.

Abstract: A system for controlling an electro-magnetic clutch for automobiles has a stepwise increase of the clutch torque for reducing the engaging shock. The system comprises a gate circuit for producing a signal by signal by shift lever clutch operation, a monostable multivibrator for producing a clutch engaging period signal by the output signal of the gate circuit for a predetermined clutch engaging period, a pulse generating circuit for producing a pulse train and a constant control signal in dependency on the mode of the clutch engaging period signal, and a control circuit for maintaining the current flowing through the magnetizing coil of the clutch at a lower value in response to the pulse train for providing a small clutch torque of the clutch and maintaining the current at a rated value in response to the constant control signal for completely engaging the clutch.