Power steering is nothing new, but it’s hard to think of a car without it. Power steering uses a motorized system, hydraulic or electrical in nature, to boost and aid the driver in its steering wheel inputs.
Without power steering, turning a car’s steering wheel at a standstill would be almost impossible. More and more cars these days are using electronic power steering systems, and we’re going to detail what it is, how it works, and how its use benefits you here!
What is Electric Power Steering?
Power steering systems once used hydraulic operation, drawing fluid from a reservoir through a pump on a car’s steering column to make turning the steering wheel a breeze. If you’ve ever driven an older car or one with a bad power steering pump, you probably noticed just how heavy the steering was sans help.
Electric power-assisted steering (EPAS) systems are appearing on more new cars, though, because it’s easier to integrate one of these systems into a car’s steering column, and they can work with a car’s driver assistance technologies, and the added electronic operations provide a tiny fuel economy benefit as well.
With an EPAS system, your car has an array of control units, sensors, and an electric motor. A torque sensor installed in your car’s steering column senses the amount of force you’re applying to the steering wheel.
The torque sensor, along with vehicle speed and steering angle sensors, feeds this information into a control module. That control module specifies just how much help the electric motor needs to help turn the wheels, and by how much, and in which direction.
Some electric power steering systems can even alter how much resistance the driver feels while turning the wheel. The electric motor provides more assistance during low-speed maneuvers to lower the resistance the driver must feel to turn the wheel.
That makes moving around tight parking lots and side streets a tad less difficult. But at speed on the highways, the electric motor begins to provide less assistance, allowing the steering wheel to be heftier, and giving a more precise and off-road responsive feel through the steering wheel.
Even though it’s a complicated mess of sensors and motors, the result is a simpler driving experience with a few more benefits for you.
Parts of Electric Power Steering
The following are the parts of the electric power steering system:
- Steering wheel
- Electric motor
- Electronic control unit (ECU)
- Torque sensor
- Steering angle sensor
- Reducing gearbox
- Battery
- Speed sensor
#1. Steering Wheel.
The primary function of the steering system is to provide steering of the vehicle as desired by the driver. It converts the rotary motion of the steering wheel into the angular turning of the front wheels.
#2. Electric Motor.
Electric Power Steering consists of an electric motor that controls the vehicle’s steering, providing an optimal and enjoyable steering experience.
The motor is a permanent magnetic field DC motor. This motor must be capable of generating torque without rotating, and it should also be able to reverse it rapidly.
#3. Electronic Control Unit (ECU).
The electronic control unit is the heart of EPS. An ECU also controls the steering sensor and vehicle speed sensor inputs and outputs, along with the above. Except for this, it performs these other three functions, which are also considered essential.
ECU manages motor current and the steering wheel mechanism. The software of this ECU is useful in monitoring the ESP System and its components, as well as in self-diagnosis and fail-safe functions. It communicates between ECU and ESP system i.e.; the ESP can read data stored in ECU.
#4. Torque Sensor.
This device is used in an electric power steering system, which measures the torque applied by the driver to the steering wheel. Using this data, the electronic control unit decides how much steering assistance to apply to the electric motor.
The torque sensor consists of input and output shafts connected by a torsion bar. The input shaft has splines while the output shaft has slots. Moving the input and output shafts creates torque in the torsion bar, which is magnetized and converted into voltage.
#5. Steering Angle Sensor.
It measures the position angle and rate of turn of the steering wheel. In simple words, it relates the steering wheel to the wheels of the vehicle to find out where the driver intends to steer.
Steering angle sensors are located in the steering column of a vehicle. In an ESP system, more than one angle sensor is used to ensure redundancy and confirmation of data.
#6. Reduction Gear.
When the driver wishes to return a steering wheel after making a great effort, such as turning at an intersection, then this reduction gear provides a smooth return movement as well as added comfort when the steering wheel is returned from great efforts of moving the wheel, such as turning when going in straight lines.
#7. Battery.
As I said above, ESP works with the aid of an electric motor and a control unit made up of some sensors.
For this, the motor works off a battery and draws power from it to assist in steering when the driver moves the steering wheel.
#8. Speed Sensor.
Speed sensors are called into play in the ESP system to sense the speed of the car and adjust the extent of the compensation or the assistance afforded to give the consummate feel of you being in control at all times, so to speak, having some control of the steering wheel.
Working of Electric Power Steering
As soon as the driver turns the steering wheel, electronic sensors on the steering column detect the movement and transmit it to the vehicle’s electrical control unit for action.
There are various inputs received by the vehicle’s electronic control unit, and it, in turn, sends a voltage signal to the electric motor located at the rear end of the steering column, engaging the gear mechanism that the gears are at present in a continuous mesh with the pinion gear, allowing the vehicle to move forward.
It is these signals emanating from the ECU indicative of voltage that switch on to the motor, precisely powered by the vehicle’s battery, and additionally give the special torque relative to the value of the received voltage signals.
A gear constantly in mesh with the pinion gear of the electric motor next follows in arrangement. It starts passing on to the pinion gear of the manifold, which is receiving torque from the rack to which it is cross-linked.
This torque applied by the pinion to the rack gives it rotation, which rotates the front wheels to the required road curves shown by the driver.
Types of Electric Power Steering
The various kinds of electric power steering systems are:
- Column Assist Type (C-EPS): The power assist unit, torque sensor, and controller are all contained in the steering column sandwich and connected by the steering column itself.
- Pinion assist type (P-EPS): A power assist unit mounted to the pinion shaft of the steering gear provides the driver with a measure of power assistance. In general, pinion assist electric power steering would have smaller cars going gradually faster.
- Direct drive type (D-EPS): These systems don’t have much complexity, but have the advantages of low inertia and low friction because the steering gear and assist unit are part of the same assembly.
- Rack assists type (R-EPS): The assisting unit is connected to the steering gear. For rack assist electric power steering systems, this can be done on mid- to full-size vehicles since they have a relatively low inertia (being the racks) and the ratios of the gears make them relatively inert.
The Pros Of Electric Power Steering Systems
Below, we list five common advantages of EPS systems.
Better Fuel Efficiency
EPS systems aren’t in a constant state of running like HPS, which lowers the dependence on the engine. EPS only pulls energy/power from the car’s battery when the steering wheel is being turned.
Easier To Maintain
EPS systems don’t have as many moving parts, and the designs are, for the most part, fairly simplistic. This leads to less wear and a lesser reliance on steering fluid.
Works With ADAS
While ADAS (Advanced Driver Assistance Systems) is a broad spectrum and aims to make vehicles safer, EPS can be integrated without much fanfare.
The amount of steering assistance also becomes more or less as the speed of the vehicle and with the driving conditions.
Lower Weight
EPS systems don’t necessitate the installation of as much space in the engine bay thanks to their compact, lightweight designs.
Better Vehicle Handling
Steering feedback is more precise and responsive, and more consistent at different speeds. This isn’t always the case, of course.
The Cons Of Electric Power Steering Systems
Below are five of the common disadvantages of EPS systems.
Less Steering Feedback
With HPS, there’s better steering feedback given to EPS, something driving aficionados might bemoan as they reach for more steering feel while at the wheel.
Potential For Something To Go Wrong
Since EPS uses sensors and electrical components (sensor and/or electric motor), failure still poses a potential risk.
Hefty Repair Costs
While lighter and designed more compactly than HPS systems, EPS can be expensive to repair due to the complexity of these electronic components.
Reliance On Electrical System
EPS can function without the engine acting as the power source, but if the electrical system itself is compromised, its assistance may not kick in.
Setup Is Key
If the EPS system isn’t properly calibrated, the feel of the steering can be less predictable.
Symptoms of a Bad ESP System
The following are several symptoms that indicate the EPS system is failing:
- ESP warning light
- Poor power assist
- Noise from the ESP motor
- Vehicle pulls in one direction
- Vibration from the steering rack
- Soft steering wheel at high speeds
#1. ESP Warning Light.
If the electric power steering is faulty, it causes the ESP (electric power steering) warning light on the car’s dashboard to illuminate. It usually appears as a red or yellow light, meaning there’s a problem with the power steering.
#2. Poor Power Assist.
If some of the ESP system parts wear out, you may experience reduced power assist as a result. It will therefore be harder to turn the steering wheel. Poor power assist is merely a loss of power assist, but it could happen either suddenly or gradually.
The sudden loss of power assist makes it difficult to keep the vehicle under your control. If loss occurs gradually, you may not notice it at first, but it will over time, making it hard for you to turn the steering wheel.
#3. Noise from the ESP motor.
If there’s a fault in the ESP, then you might hear a strange noise from the power steering motor. This noise is usually made by the grinding of the gears against one another inside the power steering motor. The noise will grow louder (to whining) as the EPS system fails.
#4. Vehicle Pulls to One Side.
This is another symptom of the ESP system, due to which, for some reason, the vehicle starts drifting off to another side of the road.
This could be deadly as it makes it difficult to keep the vehicle in the lane. The common cause of this may be due to a bad sensor or a faulty power steering motor.
#5. Vibration from the steering rack.
If you even feel a slight vibration from the steering wheel, get a mechanic to check it out as soon as possible. In this power steering, a rack and pinion are used to convert the rotational motion of the steering wheel into linear motion, thus making the wheels turn.
If the rack and pinion have not been properly lined up, it could cause vibration in the steering wheel.
#6. Soft Steering Wheel at High Speeds.
If the EPS fails, you may realize that the steering wheel is rather softer than usual at high speeds. The ESP system allows the vehicle to fine-tune the level of assistance, depending on the condition on the roads or driving conditions.
Take, for example, it provides more assistance in hard turnings on congested roads at low speed and less assistance at high speed when you’re making easy turnings. So, the steering will become stiff or hard at high speeds and at low speeds, much softer.
Wrapping It up
The conclusion I draw is that electric power steering is vital for modern cars. During driving, the electric power steering system allows for good handling and a more comfortable and less fatiguing experience when you drive.