What is the principle of power steering?
2 Answers
Electronic Hydraulic Power Steering (EHPS) operates on the same principle as traditional mechanical hydraulic power steering systems but incorporates an electric steering pump, whose activation and deactivation are controlled by the ECU. Below is an introduction to the principle of power steering: 1. When no steering action is performed, the electric steering pump is turned off, unlike mechanical hydraulic power steering pumps that are constantly connected to the engine via a belt. Normally, the speed of the electric steering pump is inversely proportional to the vehicle speed. At low speeds, the pump operates at 3000r/min, while at high speeds, it reduces to 800r/min. This results in light steering during parking and a firm, stable feel at high speeds. 2. During steering, the torque sensor detects the steering wheel's torque and direction of rotation, sending these signals to the ECU. The ECU comprehensively analyzes data such as steering wheel torque, rotation direction, and vehicle speed, then issues command signals to the motor controller. The motor then outputs corresponding torque in size and direction to provide assistance. When the vehicle is not steering, the ECU does not send command signals to the motor controller, and the motor remains inactive, helping to reduce fuel consumption. Additionally, the ECU determines the force applied to the steering wheel via an electro-hydraulic converter based on the vehicle speed signal, reducing the "floating" sensation of the steering wheel during high-speed driving.
I've been driving for thirty years, and power steering is actually quite simple. It mainly relies on hydraulics or electricity to save you effort. Older cars commonly use hydraulic power steering—the engine drives the power steering pump, which pressurizes fluid to push pistons in the steering gear. When you turn the steering wheel, a valve opens, allowing the pressurized fluid to assist the gears in turning the front wheels, making it easier on your hands. When the wheel returns to center, the valve closes, and the fluid circulates. Just remember not to hold the steering wheel at full lock for more than 5 seconds to avoid burning out the pump. If the steering feels heavy, squeaks, or leaks, it's likely due to a cracked hose or a failing power steering pump. The mechanical principle is straightforward but reliable, though steering can feel heavier when the car is cold in winter.
