Hydractive Suspension: Technology and Operation
Hydractive Suspension
Hydractive Suspension is an enhanced version of hydropneumatic suspension; it is a type of computer-controlled suspension.
Proceedings of the Suspension
Variation of elastic elements is achieved by having a third sphere that can be connected or disconnected from the other two. The connection or disconnection of the additional sphere to the other two for each axis is controlled by the stiffness regulator, one per axle.
- Soft Setting: The weight is distributed across all three spheres. The deformation is less, resulting in lower internal pressure and a softer ride.
- Hard Setting: The third sphere is isolated, and the load is distributed across the other two, increasing pressure and creating a firmer ride.
Variation of Damper Calibration
This is performed automatically. In the soft setting, fluid circulates through holes in the damper located at the third sphere. Because of the larger passage section, the lamination effect is lower. When the third sphere is isolated, the liquid only passes through the other two, resulting in a more restrictive effect, matching the elastic stiffness.
Anti-Roll Effect
The effect on roll is achieved when all three spheres are connected. The calibrated holes in the stiffness regulator limit the fluid flow between cylinders. This is known as soft anti-roll. When the regulator isolates the third sphere, communication between the cylinders of the same axle is overridden. Thus, the anti-pitching is much sharper, and fluid circulation is completely prevented between these cylinders, resulting in rigid anti-pitch.
Operation of the Hydraulic System
The connection and disconnection of the third sphere are achieved through the stiffness regulator, a 3/2 normally open valve that is servo-piloted. This pilot is in charge of the electrovalve. When the regulator is open, communication occurs between the three spheres. This will have a pilot valve integral with the shaft of the distributor valve itself so that when the pilot valve is actuated, both the pilot valve and the distributor valve receive pressure from the hydraulic circuit, driving the control valve, resulting in a soft damping effect. When the solenoid valve is energized, the pilot valve receives pressure from the circuit, resulting in a soft setting. When the control unit commands a hard setting, it de-energizes the solenoid valve, which is closed by an antagonist spring. When the solenoid valve is activated, the setting is soft, while if it is de-energized, a hard setting is imposed.
Electronic Control Circuit
Power control of electrovalves: To determine the suspension setting, a series of sensors are used. Based on the information sent by these sensors, the system determines whether to activate the regulators for a soft or hard setting.
- Steering Wheel Sensor: Detects the degree and speed of steering action, anticipating body inclinations and imposing a harder setting. (Optical Sensor)
- Vehicle Speed Sensor: Interacts with other sensors. Above 30 km/h, the system response is faster. (Inductive or Hall-effect sensor)
- Accelerator Sensor: Determines vehicle behavior, anticipating pitching. (Potentiometer, variable resistor, or Hall-effect sensor)
- Brake Pressure Sensor: Detects sudden braking and imposes a hard setting to control pitching. (Piezoresistive or piezoelectric sensor)
- Door Opening Sensor & Suspension Level Sensor