Hydraulic actuator
A pump coupling or hydraulic actuator controlling one or more limited slip couplings of a distribution system for distribution torque between front and rear axles in all wheel drive vehicles and/or distribution of torque between left and right wheels in two or four wheel drive vehicles. The hydraulic actuator includes an electric motor, a hydraulic pump, driven by a drive shaft of the electric motor, and the one or more limited slip couplings. Each limited slip coupling includes a disc package and a piston acting on the disc package, which piston is actuated by a hydraulic pump. A centrifugal regulator is connected to a rotating part of the electric motor or the hydraulic pump, which centrifugal regulator controls a pressure overflow valve, connected to the oil outlet of the hydraulic pump. The pressure is controlled by current to the electric motor or by control of the motor speed.
1. A hydraulic actuator of a distribution system of torque between front and rear axles of an all wheel drive vehicle and/or distribution of torque between left and right wheels of a two or four wheel drive vehicle, which hydraulic actuator comprises an electric motor, a hydraulic pump, driven by means of a drive shaft of the electric motor, and one or more limited slip couplings, comprising a disc package and a piston acting on the disc package, which piston is actuated by means of the hydraulic pump, wherein a centrifugal regulator is connected to a rotating part of the electric motor or the hydraulic pump, which centrifugal regulator controls a pressure overflow valve, connected to the oil outlet of the hydraulic pump.
2. The hydraulic actuator of claim 1 , wherein the rotating part is the drive shaft of the electric motor.
3. The hydraulic actuator of claim 1 , wherein a relief valve is connected to the same side of the piston of the limited slip coupling as the hydraulic pump.
4. The hydraulic actuator of claim 3 , wherein a pressure overflow valve is connected to a hydraulic piston pump.
5. The hydraulic actuator of claim 1 , wherein the pressure overflow valve comprises a washer and spring arrangement, which washer doses off an overflow outlet in one position.
6. The hydraulic actuator of claim 5 , wherein the centrifugal regulator comprises centrifugal levers acting directly on the washer of the pressure overflow valve and counteracting a spring or springs of the washer and spring arrangement.
7. The hydraulic actuator of claim 5 , wherein the centrifugal regulator comprises balls arranged between the washer of the pressure overflow valve and a ball support on the drive shaft of the hydraulic pump and the surface of the ball support, in contact with the balls, is inclined.
8. The hydraulic actuator of claim 1 , wherein the electric motor is a brush DC motor.
9. The hydraulic actuator of claim 1 , wherein a control system comprises an electrical controller and a temperature sensor integrated in the limited slip coupling and wherein the hydraulic pressure is controlled by current to the electric motor.
10. The hydraulic actuator of claim 1 , wherein an electrical controller measures variation in current to the electric motor, wherein a speed sensor is arranged sensing the speed of the drive shaft and/or wherein the electric motor is a brushless motor.
11. The hydraulic actuator of claim 1 , wherein the electric motor is constantly running.
12. The hydraulic actuator of claim 1 wherein a pressure reducing valve is placed between the oil outlet of the hydraulic; pump and a further limited slip coupling, comprising a cylinder chamber, a piston, encompassed by the cylinder chamber, and a disc package.
13. A vehicle comprising a hydraulic; actuator according to claim 1 .