Automotif Engine, Power Steering types, power steering system

POWER STEERING SYSTEM

A. Understanding power steering

Power steering is a system that serves to relieve rotate the vehicle steering system so as to produce a lightweight steering rotation without the need to employ the means to control the steering, especially at low speeds and adjust them at medium and high speeds.

At low speeds the tire friction with the road is quite high, especially for the type of low-pressure tire with a tread width.

Power steering has two types, namely the type of hydraulic equipment which uses engine power, and the other uses an electric motor, or commonly called the Electric Power Steering (EPS).

In the power steering which uses engine power, the engine power in use to drive the pump, while the type that uses electric motors, pumps driven by electric motors. Both - equally aims to generate hydraulic pressure is used to drive the piston in the power cylinder and provide additional power to the pinion and rack. Terms of a power steering should match the style of driving in which the steering effort at low speeds should be lower (lighter) and the higher the speed of the vehicle, then the effort required for driving should be smaller. To obtain an appropriate steering force, some cars have power steering with special equipment mounted on the pump (vane pump) or the gear housing. Power steering which uses a sensor mounted on the gear housing is a type of power steering with the vehicle speed sensor, where the vehicle speed detected by the speed sensor and the fluid pressure acting on the pump will be changed to change based on the speed sensor. Power steering which uses a sensor mounted on a vane pump is a type of pwer steering with engine rotation sensor (RPM). In this type of engine rpm sensing, above a certain speed lowered volume of fluid flow so that the pressure acting on the pump will be reduced.

• Use of power steering provides several advantages such as

1. Reduces steering effort
2. Very high stability during driving
3. Reduce the shock of unevenness in the road surface is channeled to the steering wheel.

• How to care so durable power steering:

1. If the vehicle will turn better roads or motion new first turn.
2. Do not be too often deflect steer get stuck / broken for too long.
3.  Choose Power Steering original oil (ATF type).
4. Choosing original spare parts when diservice.
5. To steer hydraulic rack types, suggested any protective rubber washing vehicles (boot steer) right and left is checked, whether loose, torn or other damage occurs.
6. If the parking of vehicles, should be the position of the front wheels must be straight.
7. Use of tires with low friction levels

• How the power steering:

1. Neutral position

Stream to control valve (control valve). When the control valve is in the neutral position, all the oil will flow through the control valve to channel Liberator (relief port) and back to the pump. At this time do not form pressure and pressure both sides the same arena, the piston does not move.

2. At the time of turning

By the time the steering main shaft (steeringmain shaft) rotated to one direction, the valve controller will also move to close one oil channel. Other channels will be open and there will be changes in the volume of oil flow and pressure eventually formed. On both sides of the piston will occur and the pressure difference piston will move to the low pressure side so that the oil that is in the room will be returned to the pump through a control valve.

B. Power Steering types, namely:

1. Hydraulic Power Steering

Hydraulic Power Steering is a hydraulic system (hydraulic servo) that serves to lighten the energy required to rotate the wheel, especially at low speeds and adjust the medium and high speed. At low speeds the tire friction with the road is quite high, especially for the type of low-pressure tire with a tread width.

B. How the power steering hidrolic:

When the wheel is rotated, prisoners formed by heavy vehicles and cars friction between the tire and the road surface causes the torsion bar in the rotary valve into a turn. This changes the position of the valve spool and sleeve, then direct the power steering oil under pressure to the power cylinder.

The difference in pressure on one side of the piston (which is mounted on a rack) helps move the rack to reduce the business circles. Lubricating oil that is in the other side of the power cylinder and the control valve is forced to return to the pump reservoir. At the time of steering Efforts to stop, the control valve presented by the turning force of the torsion bar, the pressure is balanced on both sides of the piston, and the front wheel back to the straight-ahead position.

Rack-and-pinion assembly is a hydraulic-mechanical unit with integral piston and rack assembly. In it there is a rotary valve that directs the flow of minyal power steering and controlling the pressure to reduce steering effort (an undertaking the power required to turn the steering wheel). When the wheel is rotated, prisoners formed by the weight of the vehicle and the friction wheel to the tire, causing torsion bar in the rotary valve tends to be somewhat off the mark. This will change the position of the valve spool and sleeve, because that takes directing pressurized lubricant to the proper end contained in the power cylinder.

The difference in pressure on the piston side (which is mounted on a rack) helps move the rack to reduce the pace of business circles. Lubricant in the power cylinder opposite urged to control valve and back to the pump reservoir. When the steering effort stops, the control valve will be presented by the force of the twisted torsion bar, the pressure on both sides of the piston will be matched, and the front wheels return to the straight ahead position.

1. Rack-and-pinion power steering system consists of:

• Rack and pinion steering gear box

Rack Pinion / Gearbox is a driver system Power Steering of the wheel over and then forwarded to the wheels with assistance from component understeel or legs vehicles (tie rod, rack end, idle arm, etc.). In the system Rack Pinion / Gearbox are piston and valve (the valve) that works according to the oil pressure channeled through Vane Pump, besides there are also a useful seal-seal Olie withstand pressure from leaking out.

1. Power steering oil pump

PS pump serves as an energy supplier of the engine with high pressure oil which is then forwarded to the Rack Pinion / Gearbox through Hose Press (high-pressure hose). Vane Pump position is always at the top of RackPinion / Gearbox. And nearly half controlled Power Steering system / set of working pumps, therefore, if there is damage to the pump is almost certainly his Power Steering system also will not alias damaged roads. Type pump a lot, among others:

piston pumps, membranes, plunger, outer gear, the gear, vane, screw and others. Pressure is needed is a continuous pressure (continue), so that the type of pump used is the type Vane or Gears. Pumps generate pressure by utilizing engine rpm, so the pumping volume is proportional to engine speed.

Setting the amount of oil flowing out of the pump is regulated by flow control valve, so it is always constant. In fact, since prisoners driving at high speed is reduced, the amount of oil flow should also be reduced, so that the steering stability is maintained On rpm sensing power steering and power steering that has a flow control valve with built-in control spool, the amount of oil flow will be regulated in accordance with the the speed of the vehicle. Fluid flow amount adjustment work / oil by the flow control valve and the control spool is as follows:

a). In Round Low

At low speed (650 up to 1250 rpm), the pressure generated by the pump will be channeled into two channels, namely x (channel flow control valve) and y (channel to control the spool). Flow passing through the channel x partially returned to the pump and partly out (P1). P1 stream forwarded past the orifice 1 and 2 and is divided into two pump output and supplied to the left of the flow control valve into the pressure P2. Differences press P1 and P2 depend spin machine. At the time of the engine rev up then there is an increase difference between P1 and P2. When the pressure P1 exceeds the strength of the spring "A", then the flow control valve will move left kek, thus opening the channel expenditure to the suction side of the pump so that the amount of flow of spending does not rise. In this condition the amount of oil flow is controlled at ± 6.6 ltr / min.

b). In Round Medium

At the time of intermediate rounds (1250 till 2500 rpm) pump discharge pressure (P1) which is working on the left side of the control spool valve has a pressure that is capable of defeating the pressure spring "B", so that the control spool valve immovable to the right. By shifting the control spool valve orifice size of the hole 2 is reduced, so the out-put pressure pump and pressure P2 is reduced which causes the flow control valve increasingly shifted to the left. So, in the middle rounds position control valve spool will be shifted to the right and out of the orifice 2, thereby reducing the volume of fluid through the orifice.

c). High Round

If the round reached more than 2500 rpm, optimum control spool valve will be pushed to the right so that the closing orifice 2 perfectly. In this condition out-put pump and P2 only through orrifce 1, so that the amount of flow into a small, namely 3.3 ltr / min. Inside there is a relief valve flow control valve that serves to regulate the working pressure. If the working pressure reached 80kg / cm2, relief valve spring will be pushed so that the relief valve opens and P2 down.

• Oil reservoir
• Oil reservoir serves to accommodate oil P / S.
•  Tubes / Hose (hose)
• This hose serves the high-pressure oil channel of Vane Pump to the Rack Pinion / Gearbox, with rotation / rotation very fast, it can cause sound effect when the hose material used is not good quality.

d. Working Principle of Hydraulic Power Steering

Power steering systems use hydraulic pressure generated by the power steering pump point is to reduce the effort required steps to turn the steering wheel. Power steering pump mounted in front of the engine. The pump used is the type of vane-type, and is driven by the crankshaft via the drive belt. Power steering oil drawn from the reservoir to the pump on when the engine is on. This oil is pressed by a power steering switch and control valve that is located in the power steering pump.

2. Electric Power Steering

In the car toyota 2005 already apply Electric Power Steering (EPS), in which the work process that originally used the power steering hydraulic system is transformed into electrical systems. A characteristic that is contained in the EPS is already not using the power steering pump. In the car toyota 2005 already apply Electric Power Steering (EPS), in which the work process that originally used the power steering hydraulic system is transformed into electrical systems.

a. The workings of the electric power steering system (EPS)

When the keys in turn to the On position, Control modules acquire electric current to stand conditions bay, along with the EPS indicator on the instrument panel lights up. And when the machine is turned on, Noise Suppressor immediately inform the control module to activate the electric motor and clutch also directly connect the motor to the steering column. One sensor located in the steering rack in charge of giving information to the control module when the wheel starts playing called Torque Sensor, this tool will provide information to the control module to what extent and how fast the wheel is rotated rounds. With that information the control module immediately sends an electrical current as needed, the electric motor will rotate the steering gear, so the process of turning the steering becomes lighter. Vehicle speed sensor serving as the car started moving. These sensors provide information to the control module on the vehicle speed, if the speed exceeded 80 km, the electric motor will be switched off so that the steering becomes so heavy and improve safety. So the EPS system regulates the amount of electrical current as required by the electric motor and provides the specific code if there is a malfunction in the system Electronic Power Steering system (EPS) includes the same components as in the conventional power steering systems. Additionally is a solenoid valve on the power steering gear box, and a close below the audio control unit located in the middle farcia panel. To control the flow of oil to the steering gear box, provided a solenoid which works on the basis of the current control module that receives signals from the VSS (Vehicle Speed Sensor) and TPS. The workings of Electric Power Steering System (EPS) is currently playing a key to the ON position, the Control Module obtaining electrical current for stand-by condition, along with the EPS indicator on the instrument panel lights up. Currently living machine, Noise Suppressor immediately inform the Control Module to enable the electric motor and clutch immediately connect the motor to the steering column. One sensor located in the steering rack in charge of giving information to the Control Module when the wheel starts playing. Called Torque Sensor, it sends information about the extent to which the wheel is rotated and how fast it spins. With two such information, Control Module immediately sent an electric current as needed to the electric motor to rotate the steering gear, this way the process of turning the steering becomes lighter. Vehicle Speed Sensor duty once the car starts moving. These sensors provide information to the control module on the vehicle speed. At high speeds, generally starting from 80 km / h, the electric motor will be deactivated by the Control Module. With so steering becomes heavier thus increasing safety. So the EPS system regulates the amount of electrical current supplied to the electric motor only as needed. In addition to the working set of electric motors based on the information from the sensors, Control Module also detect if there is a malfunction of the EPS system. EPS indicator light on the instrument panel will light up if there is damage to certain flashing. Furthermore, Control Module deactivate the electric motor and clutch will disconnect the motor with the steering column. However, because the steering system is equipped with EPS is still connected to the wheel via a steel rod, it is still possible to drive the car. Although turning the steering will feel heavy as steering without power steering. Electric Power Steering (EPS) using some electronic devices such as:

1. Control Module: For a computer to adjust the EPS work.
2. Electric motors: Duty to directly help ease the steering wheel rotation.
3. Vehicle Speed Sensor: Located in the gearbox and in charge of telling the control module on the speed of the car.
4. Torque Sensor: Being on the steering column with the task of giving information to the control module when the wheel starts playing by the driver.
5.  Clutch: This clutch is between the motor and the steering column. Its job to connect and disconnect the motor with the steering column according to the conditions.
6. Noise Suppressor: Acting as sensors that detect the engine is running or not.
7. On-board Diagnostic Display: in the form of an indicator on the instrument panel will light up if there is a problem with a bunch of EPS systems.

b. Excellence Electric Power Steering

EPS not only perform the function of normal power steering, but also can control the pressure of hydraulic pressure that reacts based counter-force on the plunger that is fixed in the gear box input shaft, because that is the characteristic steering effort vs. hydraulic pressure varies depending on the speed of the vehicle to provide optimum steering characteristics fit with vehicle speed and steering conditions.

1. When the car is stationary and in a state of slow running round light steering.
2. Setting steering effort based on vehicle speed.
3.  At medium speed and fast, it will increase steering effort to increase the stability and comfort of the steering wheel.
4.  In medium speed and fast, when the rudder position at or near the neutral position, the plunger will increase the reactionary function steering effort so that the steering is more stable.
5. When the vehicle passes through the damaged road at medium speed and fast, although there is a big obstacle from the road surface, but will not affect the direction of the steering control, because the output pressure hydraulic steering effort to be the same height as the conventional power steering.
6. This system has a fail-safe function that despite the electrical system, including the control units and sensors, but the normal characteristics of the power steering can still be in the can.

The problems that arise are usually the steering wheel / steer feels weight so that there are indications that the power steering became one possible causes, though not the only one causes. If there are problems it is in doing inspection of the power steering system is as follows:

steering belt

1. Check the power steering belt (belt player power steering pump). If the condition is damaged it must be replaced, but if only a loose / loose belt do its firmness adjustment (see specifications in workshop manual).
2. Check the power steering oil. Check the amount and quality of the oil by looking deep recervoir stick on the tube. Do also check for leaks that may occur on the pipe / hose coupling. If there is a leak to fix or resolve prior leakages occurring, add the oil and power steering on recervoir do bleeding. Bleeding is done by turning the engine at 100 rpm, and maximum steering wheel is rotated to the right and left three or emapat times.

Oil replacement done if oil is found already oxidized / foamy / frothy and even existing or emulsion. Replacement of oil is done in the following way:

• Raise the front of the vehicle
• Remove the return pipe and remove the oil from the oil recervoir
• With the engine idling, rotate the maximum steering wheel right and left, taking out the oil.
• Turn off the engine.
• Fill the new oil to recervoir.
• Turn the engine at 1000 rpm.
• After the oil out through the drain pipe behind, make sure that the oil direcervoir always full and the oil that comes out through the return channel does not mix the air.
• Replace the return pipe oil from recervoir.
• Perform exhaust air that possibility remains (bleeding) in the manner described above.
• Ensure that at the time the machine is turned off, the increase in oil level on recervoir not more than 5 mm.

3). Check the oil pressure power steering.

By using a pressure gauge make sure that the oil pressure is not lower than 65 kg / cm at maximum turn and conditions or at idle and channels blocked pressure gauge (max blocking 10 seconds).