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Car Tech 101: Power steering explained
Car Tech 101: Power steering explained
Published: 2014/04/01
Channel: CNET
How to Flush Your Power Steering Fluid
How to Flush Your Power Steering Fluid
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HOW IT WORKS: Power Steering (720p)
HOW IT WORKS: Power Steering (720p)
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Driving With No Power Steering? - What it
Driving With No Power Steering? - What it's like
Published: 2016/10/23
Channel: Channel C.G.E.
DIY: How to Troubleshoot a Power Steering System
DIY: How to Troubleshoot a Power Steering System
Published: 2015/04/17
Channel: 4DIYers
Fixing Noisy Power Steering On Your Car
Fixing Noisy Power Steering On Your Car
Published: 2014/03/04
Channel: Scotty Kilmer
Hydraulic Power Steering
Hydraulic Power Steering
Published: 2016/06/28
Channel: AutoMate Training
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What no power steering feels like
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Channel: Mikes DIY Garage
Power Steering Systems: how they work
Power Steering Systems: how they work
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Channel: Autofácil
How To Check Your Power Steering System – AutoZone Car Care
How To Check Your Power Steering System – AutoZone Car Care
Published: 2011/04/15
Channel: AutoZone
Hondas and acuras: Should you remove power steering?
Hondas and acuras: Should you remove power steering?
Published: 2014/03/12
Channel: SP Tuning
Fix Sticking Power Steering
Fix Sticking Power Steering
Published: 2010/11/04
Channel: Scotty Kilmer
Power Steering Animation
Power Steering Animation
Published: 2011/03/09
Channel: Pedders Suspension
1999 Civic Power Steering Rack Replacement (Part 1) - EricTheCarGuy
1999 Civic Power Steering Rack Replacement (Part 1) - EricTheCarGuy
Published: 2012/08/20
Channel: EricTheCarGuy
Electric Power Steering conversion
Electric Power Steering conversion
Published: 2017/04/02
Channel: Ollari's
Cómo Cambiar El Aceite Hidráulico Del Volante- Power Steering Fluid
Cómo Cambiar El Aceite Hidráulico Del Volante- Power Steering Fluid
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Channel: DestinyRoyal
How to Diagnose and Fix a Noisy or Sticking Power Steering Wheel
How to Diagnose and Fix a Noisy or Sticking Power Steering Wheel
Published: 2016/03/19
Channel: Ratchets And Wrenches
How To Change Power Steering Fluid -EricTheCarGuy
How To Change Power Steering Fluid -EricTheCarGuy
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Channel: EricTheCarGuy
Power Steering: "Hydraulic Steering Principles of Operation" 1955 US Army Auto Mechanics
Power Steering: "Hydraulic Steering Principles of Operation" 1955 US Army Auto Mechanics
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Hydraulic Steering
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Channel: Jay Gee
How a Power Steering Box Works 610BOB
How a Power Steering Box Works 610BOB's Teardowns
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Channel: 610GARAGE
Power Steering Fluid Change QUICK and EASY
Power Steering Fluid Change QUICK and EASY
Published: 2014/05/09
Channel: ChrisFix
Car Steering - Rack and Pinion - Explained
Car Steering - Rack and Pinion - Explained
Published: 2012/05/16
Channel: Engineering Explained
Fixing A Leaking Power Steering Rack
Fixing A Leaking Power Steering Rack
Published: 2016/02/02
Channel: Scotty Kilmer
POWER STEERING vs MANUAL STEERING || WHICH ONE I SHOULD BUY? || DESI DRIVING SCHOOL
POWER STEERING vs MANUAL STEERING || WHICH ONE I SHOULD BUY? || DESI DRIVING SCHOOL
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Channel: DESI DRIVING SCHOOL
Porque Los  Carros Modernos No Traen Recipiente de liquido de Power Steering
Porque Los Carros Modernos No Traen Recipiente de liquido de Power Steering
Published: 2017/07/21
Channel: AYUDA TV
Power Steering Working Principle Animation
Power Steering Working Principle Animation
Published: 2013/08/20
Channel: Bibin S M
Como Cambiar la Bomba del Hidraulico - power steering
Como Cambiar la Bomba del Hidraulico - power steering
Published: 2015/04/21
Channel: AYUDA TV
Aftermarket Electric Power Steering in Suzuki Alto VXR (2006)
Aftermarket Electric Power Steering in Suzuki Alto VXR (2006)
Published: 2015/09/21
Channel: Diddly Doodly
How to repair, fix, stop Honda, Acura power steering whining noise.
How to repair, fix, stop Honda, Acura power steering whining noise.
Published: 2016/02/03
Channel: George Melnik
How to Fill and Bleed Power Steering Fluid System 2001 Ford Ranger Buy Parts from 1AAuto.com
How to Fill and Bleed Power Steering Fluid System 2001 Ford Ranger Buy Parts from 1AAuto.com
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POWER STEERING PUMP PULLEY REMOVAL
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Channel: 2CarPros
2008 Acura MDX Power Steering Pump Replacement
2008 Acura MDX Power Steering Pump Replacement
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How To Put Power Steering In A Classic Ford Mustang - Part 1
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Power Steering Pump Replacement Mercedes Benz ML500 1998-2005
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Channel: 2CarPros
2000 Dodge Dakota Power Steering High Pressure Hose
2000 Dodge Dakota Power Steering High Pressure Hose
Published: 2016/03/28
Channel: Average Guys Garage
How to Change a Power Steering Pump - 94 Ford Ranger 4.0 V6
How to Change a Power Steering Pump - 94 Ford Ranger 4.0 V6
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Channel: Hank's Small Engine Repair
2006 Honda Odyssey Power Steering Rack Replacement
2006 Honda Odyssey Power Steering Rack Replacement
Published: 2017/06/23
Channel: EricTheCarGuy
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Ford Quick Tips #75: C-III Power Steering Pump Removal Trick!
Published: 2017/04/22
Channel: FordTechMakuloco
97 Chevy Tahoe DIY- How To Replace a Power Steering Gear Box
97 Chevy Tahoe DIY- How To Replace a Power Steering Gear Box
Published: 2016/08/15
Channel: 512kjt
How to Install Replace Power Steering Oil Cooler 2002-08 Dodge Ram 1500 BUY AUTO PARTS AT 1AAUTO.COM
How to Install Replace Power Steering Oil Cooler 2002-08 Dodge Ram 1500 BUY AUTO PARTS AT 1AAUTO.COM
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Channel: 1A Auto Parts
Mustang Power Steering Control Valve Repair Kit 1965-1970 Installation
Mustang Power Steering Control Valve Repair Kit 1965-1970 Installation
Published: 2015/10/22
Channel: CJ Pony Parts
1992 Ford f150 Power Steering Pump Replacement Bronco
1992 Ford f150 Power Steering Pump Replacement Bronco
Published: 2016/07/17
Channel: Oldsmob455
PSt Car Service - repair of power steering systems
PSt Car Service - repair of power steering systems
Published: 2012/02/18
Channel: Ремонт рулевых реек. Рулевая рейка. Киев.
How to Flush Your Power Steering Fluid - DIY and Save Money
How to Flush Your Power Steering Fluid - DIY and Save Money
Published: 2014/10/21
Channel: Ratchets And Wrenches
How to Replace a Jeep TJ Power Steering Box DIY
How to Replace a Jeep TJ Power Steering Box DIY
Published: 2016/05/30
Channel: Bullshitkorner
Jeep Wrangler JK Driveway Power Steering Flush
Jeep Wrangler JK Driveway Power Steering Flush
Published: 2016/06/23
Channel: OURv
Ford Electric Power Steering Failure Identified
Ford Electric Power Steering Failure Identified
Published: 2016/06/30
Channel: K Smith
FATALNYA OLI POWER STEERING HABIS
FATALNYA OLI POWER STEERING HABIS
Published: 2017/01/13
Channel: mr mechanic
Kia or Hyundai Motor Driven Power Steering Clunk Noise MDPS Rubber Coupler // 현대 아반떼
Kia or Hyundai Motor Driven Power Steering Clunk Noise MDPS Rubber Coupler // 현대 아반떼
Published: 2015/12/01
Channel: Auto Parts Direct To You
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WIKIPEDIA ARTICLE

From Wikipedia, the free encyclopedia
  (Redirected from Electromechanical steering)
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In automobiles, power steering (also power assisted steering (PAS) or steering assist system) helps drivers steer by augmenting steering effort of the steering wheel.

Hydraulic or electric actuators add controlled energy to the steering mechanism, so the driver can provide less effort to turn the steered wheels when driving at typical speeds, and reduce considerably the physical effort necessary to turn the wheels when a vehicle is stopped or moving slowly. Power steering can also be engineered to provide some artificial feedback of forces acting on the steered wheels.

Hydraulic power steering systems for cars augment steering effort via an actuator, a hydraulic cylinder that is part of a servo system. These systems have a direct mechanical connection between the steering wheel and the linkage that steers the wheels. This means that power-steering system failure (to augment effort) still permits the vehicle to be steered using manual effort alone.

Electric power steering systems use electric motors to provide the assistance instead of hydraulic systems. As with hydraulic types, power to the actuator (motor, in this case) is controlled by the rest of the power-steering system.

Other power steering systems (such as those in the largest off-road construction vehicles) have no direct mechanical connection to the steering linkage; they require electrical power. Systems of this kind, with no mechanical connection, are sometimes called "drive by wire" or "steer by wire", by analogy with aviation's "fly-by-wire". In this context, "wire" refers to electrical cables that carry power and data, not thin-wire-rope mechanical control cables.

Some construction vehicles have a two-part frame with a rugged hinge in the middle; this hinge allows the front and rear axles to become non-parallel to steer the vehicle. Opposing hydraulic cylinders move the halves of the frame relative to each other to steer.

History[edit]

The first power steering system on an automobile was apparently installed in 1876 by a man with the surname of Fitts, but little else is known about him.[1] The next power steering system was put on a Columbia 5-ton truck in 1903 where a separate electric motor was used to assist the driver in turning the front wheels.[1][2]

Robert E. Twyford, a resident of Pittsburgh, Pennsylvania, included a mechanical power steering mechanism as part of his patent (U.S. Patent 646,477) issued on April 3, 1900 for the first four-wheel drive system.[3]

Francis W. Davis, an engineer of the truck division of Pierce-Arrow, began exploring how steering could be made easier, and in 1926 invented and demonstrated the first practical power steering system.[4][5][6] Davis moved to General Motors and refined the hydraulic-assisted power steering system, but the automaker calculated it would be too expensive to produce.[5] Davis then signed up with Bendix, a parts manufacturer for automakers. Military needs during World War II for easier steering on heavy vehicles boosted the need for power assistance on armored cars and tank-recovery vehicles for the British and American armies.[5]

Chrysler Corporation introduced the first commercially available passenger car power steering system on the 1951 Chrysler Imperial under the name "Hydraguide".[7] The Chrysler system was based on some of Davis' expired patents. General Motors introduced the 1952 Cadillac with a power steering system using the work Davis had done for the company almost twenty years earlier.[8]

Charles F. Hammond from Detroit filed several patents for improvements of power steering with the Canadian Intellectual Property Office in 1958.[9][10][11]

Most new vehicles now have power steering, owing to the trends toward front wheel drive, greater vehicle mass, and wider tires, which all increase the required steering effort. Heavier vehicles, as are common in some countries, would be extremely difficult to maneuver at low speeds, while vehicles of lighter weight may not need power assisted steering at all.

Hydraulic systems[edit]

A power steering fluid reservoir and pulley driven pump

Hydraulic power steering systems work by using a hydraulic system to multiply force applied to the steering wheel inputs to the vehicle's steered (usually front) road wheels.[12] The hydraulic pressure typically comes from a gerotor or rotary vane pump driven by the vehicle's engine. A double-acting hydraulic cylinder applies a force to the steering gear, which in turn steers the roadwheels. The steering wheel operates valves to control flow to the cylinder. The more torque the driver applies to the steering wheel and column, the more fluid the valves allow through to the cylinder, and so the more force is applied to steer the wheels.[13]

One design for measuring the torque applied to the steering wheel has a torque sensor – a torsion bar at the lower end of the steering column. As the steering wheel rotates, so does the steering column, as well as the upper end of the torsion bar. Since the torsion bar is relatively thin and flexible, and the bottom end usually resists being rotated, the bar will twist by an amount proportional to the applied torque. The difference in position between the opposite ends of the torsion bar controls a valve. The valve allows fluid to flow to the cylinder which provides steering assistance; the greater the "twist" of the torsion bar, the greater the force.

Since the hydraulic pumps are positive-displacement type, the flow rate they deliver is directly proportional to the speed of the engine. This means that at high engine speeds the steering would naturally operate faster than at low engine speeds. Because this would be undesirable, a restricting orifice and flow-control valve direct some of the pump's output back to the hydraulic reservoir at high engine speeds. A pressure relief valve prevents a dangerous build-up of pressure when the hydraulic cylinder's piston reaches the end of its stroke.

The steering booster is arranged so that should the booster fail, the steering will continue to work (although the wheel will feel heavier). Loss of power steering can significantly affect the handling of a vehicle. Each vehicle owner's manual gives instructions for inspection of fluid levels and regular maintenance of the power steering system.

The working liquid, also called "hydraulic fluid" or "oil", is the medium by which pressure is transmitted. Common working liquids are based on mineral oil.

Some modern systems also include an electronic control valve to reduce the hydraulic supply pressure as the vehicle's speed increases; this is variable-assist power steering.

DIRAVI variable-assist power steering[edit]

DIRAVI innovated the now common benefit of speed sensitive steering.[14]

In this power steering system, the force steering the wheels comes from the car's high pressure hydraulic system and is always the same no matter what the road speed is. Turning the steering wheel moves the wheels simultaneously to a corresponding angle via a hydraulic cylinder. In order to give some artificial steering feel, there is a separate hydraulically operated system that tries to turn the steering wheel back to centre position. The amount of pressure applied is proportional to road speed, so that at low speeds the steering is very light, and at high speeds it is very difficult to move more than a small amount off centre.

It was invented by Citroën of France.

As long as there is pressure in the car's hydraulic system, there is no mechanical connection between the steering wheel and the roadwheels. This system was first introduced in the Citroën SM in 1970, and was known as 'VariPower' in the UK and 'SpeedFeel' in the U.S.

Electro-hydraulic systems[edit]

Electro-hydraulic power steering systems, sometimes abbreviated EHPS, and also sometimes called "hybrid" systems, use the same hydraulic assist technology as standard systems, but the hydraulic pressure comes from a pump driven by an electric motor instead of a drive belt at the engine.

In 1965, Ford experimented with a fleet of "wrist-twist instant steering" equipped Mercury Park Lanes that replaced the conventional large steering wheel with two 5-inch (127 mm) rings, a fast 15:1 gear ratio, and an electric hydraulic pump in case the engine stalled.[15][16]

In 1988, the Subaru XT6 was fitted with a unique Cybrid adaptive electro-hydraulic steering system that changed the level of assistance based on the vehicle's speed.

In 1990, Toyota introduced its second-generation MR2 with electro-hydraulic power steering. This avoided running hydraulic lines from the engine (which was behind the driver in the MR2) up to the steering rack. In 1994 Volkswagen produced the Mark 3 Golf Ecomatic, with an electric pump. This meant that the power steering would still operate while the engine was stopped by the computer to save fuel.[17] Electro-hydraulic systems can be found in some cars by Ford, Volkswagen, Audi, Peugeot, Citroen, SEAT, Škoda, Suzuki, Opel, MINI, Toyota, Honda, and Mazda.

Electric systems[edit]

Electric power assisted steering (EPS/EPAS) or motor-driven power steering (MDPS) uses an electric motor to assist the driver of a vehicle. Sensors detect the position and torque of the steering column, and a computer module applies assistive torque via the motor, which connects to either the steering gear or steering column. This allows varying amounts of assistance to be applied depending on driving conditions. Engineers can therefore tailor steering-gear response to variable-rate and variable-damping suspension systems, optimizing ride, handling, and steering for each vehicle.[18] On Fiat group cars the amount of assistance can be regulated using a button named "CITY" that switches between two different assist curves, while most other EPS systems have variable assist. These give more assistance as the vehicle slows down, and less at faster speeds.

A mechanical linkage between the steering wheel and the steering gear is retained in EPAS. In the event of component failure or power failure that causes a failure to provide assistance, the mechanical linkage serves as a back-up. If EPAS fails, the driver encounters a situation where heavy effort is required to steer. This heavy effort is similar to that of an inoperative hydraulic steering assist system[citation needed]. Depending on the driving situation, driving skill and strength of the driver, steering assist loss may or may not lead to a crash. The difficulty of steering with inoperative power steering is compounded by the choice of steering ratios in assisted steering gears vs. fully manual. The NHTSA has assisted car manufacturers with recalling EPAS systems prone to failure.[19]

Electric systems have an advantage in fuel efficiency because there is no belt-driven hydraulic pump constantly running, whether assistance is required or not, and this is a major reason for their introduction. Another major advantage is the elimination of a belt-driven engine accessory, and several high-pressure hydraulic hoses between the hydraulic pump, mounted on the engine, and the steering gear, mounted on the chassis. This greatly simplifies manufacturing and maintenance. By incorporating electronic stability control electric power steering systems can instantly vary torque assist levels to aid the driver in corrective maneuvers.[20]

The first electric power steering system appeared on the Suzuki Cervo in 1988.[21] The system has been applied by various automobile manufacturers.

Electrically variable gear ratio systems[edit]

In 2000, the Honda S2000 Type V featured the first electric power variable gear ratio steering (VGS) system.[22] In 2002, Toyota introduced the "Variable Gear Ratio Steering" (VGRS) system on the Lexus LX 470 and Landcruiser Cygnus, and also incorporated the electronic stability control system to alter steering gear ratios and steering assist levels. In 2003, BMW introduced "active steering" system on the 5-series.[23]

This system should not be confused with variable assist power steering, which varies steering assist torque, not steering ratios, nor with systems where the gear ratio is only varied as a function of steering angle. These last are more accurately called non-linear types (e.g. Direct-Steer offered by Mercedes); a plot of steering-wheel position versus axle steering angle is progressively curved (and symmetrical).

References[edit]

  1. ^ a b Schultz, Mort (May 1985). "Steering: A Century of Progress". Popular Mechanics. 162 (5): 59. ISSN 0032-4558. Retrieved 8 November 2014. 
  2. ^ Wren, James A.; Wren, Genevieve J. (1979). Motor Trucks of America. University of Michigan Press. p. 23. ISBN 9780472063130. Retrieved 8 November 2015. 
  3. ^ "Driving-gear for motor-carriages - US patent 646477 A". Google. Retrieved 29 May 2015. 
  4. ^ Nunney, Malcolm James (2006). Light and Heavy Vehicle Technology. Elsevier Science. p. 521. ISBN 978-0-7506-8037-0. Retrieved 18 June 2010. 
  5. ^ a b c Howe, Hartley E. (February 1956). "Mr. Power Steering's Ship Comes In". Popular Science. 168 (2): 161–164, 270. Retrieved 28 May 2015. 
  6. ^ "The Waltham Museum’s Hall-of-Fame". Waltham Museum. Retrieved 8 November 2015. 
  7. ^ Lamm, Michael (March 1999). "75 years of Chryslers". Popular Mechanics. 176 (3): 75. Retrieved 28 May 2015. 
  8. ^ Watson, Bill (22 Mar 2006). "History of Power Steering". Imperial Automobile Club Archives. Archived from the original on 8 December 2010. Retrieved 8 November 2015. 
  9. ^ "Manual and power actuated steering mechanism for motor vehicles". Canadian Intellectual Property Office. 
  10. ^ "Manual and power actuated steering gear". Canadian Intellectual Property Office. 
  11. ^ "Manual and power actuated steering mechanism for motor vehicles". Canadian Intellectual Property Office. 
  12. ^ Nice, Karim (31 May 2001). "Rack-and-pinion Steering - How Car Steering Works". Auto.howstuffworks.com. p. 2. Retrieved 28 May 2015. 
  13. ^ Nice, Karim (31 May 2001). "Power Steering - How Car Steering Works". Auto.howstuffworks.com. p. 4. Retrieved 28 May 2015. 
  14. ^ "Top 5: Citroen SM innovations that saw the future (video)". CNET. 5 August 2014. Retrieved 28 May 2015. 
  15. ^ "Will a twist of your wrist steer your next car?". Popular Science. 186 (4): 83. February 1984. Retrieved 8 September 2015. 
  16. ^ Markovich, Alex (April 1965). "Look, Ma-No Wheel!". Popular Mechanics. 123 (4): 91–93. Retrieved 8 September 2015. 
  17. ^ "The Golf Ecomatic Page". Deylan.co.uk. Retrieved 8 November 2015. 
  18. ^ Keebler, Jack (May 1986). "So long, hydraulics - the electronic revolution in power steering". Popular Science. 228 (5): 50–56. Retrieved 8 September 2015. 
  19. ^ "Ready for another recall? NHTSA investigating Ford for more power steering problems". Newsome Melton law firm. 7 January 2015. Retrieved 28 May 2015. 
  20. ^ "Electric power steering: one good turn deserves another". embedded.com. Retrieved 2011-09-07. 
  21. ^ Nakayama, T.; Suda, E. (1994). "The present and future of electric power steering". International Journal of Vehicle Design. 15: 243. Retrieved 8 November 2015. 
  22. ^ "Honda to Launch S2000 Type V Equipped with the World's First Variable Gear Ratio Steering (VGS) System" (Press release). Honda News. 7 July 2000. Retrieved 8 September 2015. 
  23. ^ "BMW » First Drive: 2004 BMW 5-Series". CanadianDriver. 2003-06-02. Archived from the original on October 16, 2009. Retrieved 2009-12-08. 

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