Which type of steering is best for what vehicle?

1,040 views
983 views

Published on

The first thing to remember about steering is that it is all about geometry and durability of components. Before discussing which type of steering is best for what vehicle, we need a review of existing steering systems, attendant problems, and their potential for improvement.

Read also more here: http://bit.ly/steering-articles

Published in: Automotive, Business
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
1,040
On SlideShare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
30
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Which type of steering is best for what vehicle?

  1. 1. Which type of steering is best for what vehicle?Brakes and steering are the most critical parts of a car, even more than the power train. A carrolling down hill without the engine on can be just as much of a death trap when nobody cansteer or stop it. The first thing to remember about steering is that it is all about geometry anddurability of components. Before discussing which type of steering is best for what vehicle, weneed a review of existing steering systems, attendant problems, and their potential forimprovement.Basic steering systemsThere are two major areas: linkage and steering mechanism. Arrangements will vary, but mostlinkage systems consist of ball-type joints (tie rod ends, control arms), intermediate links(Pitman arm – also called “steering arm”, drag link), threaded adjuster sleeves, and links. Major parts of a typical front end linkage system [1] -1--------------------------------------------------------------------------------------------------------------------------------- IQPC GmbH | Friedrichstr. 94 | D-10117 Berlin, Germany t: +49 (0) 30 2091 3330 | f: +49 (0) 30 2091 3263 | e: eq@iqpc.de | w: www.iqpc.de Visit IQPC for a portfolio of topic-related events, congresses, seminars and conferences: www.iqpc.de
  2. 2. Front wheel suspension assembly - Left front wheel suspension of a Saab QuantumIV with double wishbones, showing kingpin axis, wheel hub, disc brake, steering arm and tie rod end [2]There are two basic steering assemblies: recirculating ball bearings, and rack and pinion. Therecirculating ball bearing system contains an “endless belt” of ball bearings that serve toreduce friction between the steering wheel shaft and the main linkage – Pitman arm - to thelinkage assembly. This shaft turns right or left (indicated by arrows) in accordance with where the car is turning. To the linkage – tie rods, drag link, and control arm assembly Typical recirculating ball assembly at the end of the steering shaft [3] -2--------------------------------------------------------------------------------------------------------------------------------- IQPC GmbH | Friedrichstr. 94 | D-10117 Berlin, Germany t: +49 (0) 30 2091 3330 | f: +49 (0) 30 2091 3263 | e: eq@iqpc.de | w: www.iqpc.de Visit IQPC for a portfolio of topic-related events, congresses, seminars and conferences: www.iqpc.de
  3. 3. Rack and pinion steering consists of a straight toothed bar (rack) and a gear (pinion) that rollsthe bar back and forth. Rack and pinion concept [4]The bar is attached to the tie rods that connect to the wheel, as depicted in the followingdiagram of a typical rack and pinion assembly. Steering mechanism – rack and pinion [5]The main advantage of the recirculating ball assembly is that the ball bearings reduce frictionconsiderably. There is a steering wheel play and it is adjustable, usually by a slotted bolt witha securing nut mounted on top of the housing. The rack and pinion, while giving the driver asense of directly steering the vehicle, it is not adjustable. Once the rack and pinion assemblywears out, they have to be replaced. -3--------------------------------------------------------------------------------------------------------------------------------- IQPC GmbH | Friedrichstr. 94 | D-10117 Berlin, Germany t: +49 (0) 30 2091 3330 | f: +49 (0) 30 2091 3263 | e: eq@iqpc.de | w: www.iqpc.de Visit IQPC for a portfolio of topic-related events, congresses, seminars and conferences: www.iqpc.de
  4. 4. Power assistance methodsHydraulicPower steering originally was used on the SS Great Eastern in 1866 [6]. While one may notrealize, power steering for vehicles pre-dated the Model T Ford in 1909. In 1902 Frederick W.Lanchester in the UK patented a hydraulic power steering system for cars. On 30 August 1932,Klara Gailis filed the first U.S. patent. The cost of these systems kept them from beingattached to cars, but during World War Two, they were needed on heavy vehicles. In 1951, theChrysler Imperial emerged with its "Hydraguide” power steering system, the first one mass-produced for the public.The basic modern hydraulic system consists of: Steering torque detector Controlled pressure distributor case/housing containing ports and valves Hydraulic booster pump Tank with a working liquid, often mineral oil based Connection hoses.These are configured typically as indicated by the following: -4--------------------------------------------------------------------------------------------------------------------------------- IQPC GmbH | Friedrichstr. 94 | D-10117 Berlin, Germany t: +49 (0) 30 2091 3330 | f: +49 (0) 30 2091 3263 | e: eq@iqpc.de | w: www.iqpc.de Visit IQPC for a portfolio of topic-related events, congresses, seminars and conferences: www.iqpc.de
  5. 5. Typical hydraulic power steering system [7]Fluid from the reservoir travels through pump with the rotating vanes, to the various ports asindicated by the arrows, through the rack and back to the reservoir. The pump vane turnseither clockwise or counterclockwise to deliver pressure to the appropriate side of the rack –chamber A or chamber B. Chambers A and B lead to the rack. -5--------------------------------------------------------------------------------------------------------------------------------- IQPC GmbH | Friedrichstr. 94 | D-10117 Berlin, Germany t: +49 (0) 30 2091 3330 | f: +49 (0) 30 2091 3263 | e: eq@iqpc.de | w: www.iqpc.de Visit IQPC for a portfolio of topic-related events, congresses, seminars and conferences: www.iqpc.de
  6. 6. Pump vanes in hydraulic power steering pump [8]ElectricWhile hydraulic power steering will shut off when the motor is not running (because of thepower steering pump being driven by a belt around the crankshaft pulley) electric motor assistwill operate as long as there is battery power available. This can be important if the car ismoving with the motor not running for some reason (e.g., being pushed started, towed, or iscoasting down a hill) and needs to be steered by a person. Another advantage of electric-assist power steering is that it does not rob power from the motor and is a demand-onlysystem. Hydraulic systems run constantly, and during high speeds power assisted steering isnot necessary, because of the gyroscopic action and inertial motion of the wheels stabilizes theforward thrust of the car. The power is used only when needed. Still, another advantage is thatthere are no bulky hydraulic lines that can deteriorate or get in the way of other repairs.Hydraulic systems not only are bulky, they are much heavier than electric-based ones, thusmaking for a more fuel-efficient vehicle. Of course, if the electric system fails, then for notsuch a strong person it is almost impossible to steer the car. With the hydraulic system, aperson often has advanced warning of failure, such as a low fluid level in the pump reservoir orworn vee belt.In the basic system, an electric motor is connected to the steering wheel shaft and turns inaccordance with the resistance generated from the wheels transmitted through the steeringcolumn, i.e., the torque. A torque sensor operating through a controller tells the motor howfast to turn. This is increasingly being done by regulating the magnetic fields in the stator ofthe brushless permanent magnet (BPM) motor used to drive the rack. In addition, there is a -6--------------------------------------------------------------------------------------------------------------------------------- IQPC GmbH | Friedrichstr. 94 | D-10117 Berlin, Germany t: +49 (0) 30 2091 3330 | f: +49 (0) 30 2091 3263 | e: eq@iqpc.de | w: www.iqpc.de Visit IQPC for a portfolio of topic-related events, congresses, seminars and conferences: www.iqpc.de
  7. 7. sensor detecting wheel rotation that helps modulate the motors signal voltage, which, throughthe well-known formula E=IR (volts equals ohms multiplied by amperage) determine theamperage, or power input to the motor. Another sensor detects engine speed; not as muchpower assist is needed when the vehicle is moving faster, so the power assist unit needs to becut back. The more amperage supplied to the motor, the faster it turns. Voltage signals canbe negative or positive, thus causing the motor to move the rack in the proper direction. Typical electric-assisted power steering system – basic components [9]Hybrid systemsThere are hydro-electric power steering assist systems, which use a combination of an electricmotor and fluid. The major feature is that an electric motor powers the pump driving thehydraulic fluid, rather than the motor being the propellant. Hence, the advantage is gained ofthe system being functional if the vehicles engine stops and as long as there is battery power.Of course, this doesnt resolve the hydraulic line and weight issues. Want to learn more about the latest technologies and developments in braking systems? Visit our download centre for more articles, whitepapers and interviews: http://bit.ly/steering-articles -7--------------------------------------------------------------------------------------------------------------------------------- IQPC GmbH | Friedrichstr. 94 | D-10117 Berlin, Germany t: +49 (0) 30 2091 3330 | f: +49 (0) 30 2091 3263 | e: eq@iqpc.de | w: www.iqpc.de Visit IQPC for a portfolio of topic-related events, congresses, seminars and conferences: www.iqpc.de
  8. 8. References (Subject is indicated by URL – accessed 9 July 2011)[1] http://autorepair.about.com/library/bl244lib.htm[2] http://en.wikipedia.org/wiki/File:Suspension.jpg[3] Adapted from http://en.wikipedia.org/wiki/File:RecirculatingBall.png[4] http://en.wikipedia.org/wiki/Steering[5] http://autorepair.about.com/library/bl244lib.htm[6] http://en.wikipedia.org/wiki/Power_steering[7] MarcusRösth Hydraulic Power Steering System Design in Road Vehicles - Analysis, Testingand Enhanced Functionality, Linköping Studies in Science and Technology. Linköping Studies inScience and Technology. Dissertations, No. 1068 Division of Fluid and Mechanical EngineeringSystems, Department of Mechanical Engineering, Linköping University, SE–581 83 Linköping,Sweden 2007, p. 20.[8] Ibid. pp. 21-22[9] http://www.insightcentral.net/encyclopedia/eneps.html[10] http://en.wikipedia.org/wiki/Power_steering[11] http://www.autoobserver.com/2010/11/compact-cars-are-bigger-and-heavier-than-ever-edmundscom-reports.html[12] http://auto.howstuffworks.com/hy-wire3.htm[13] Ibid.[14] Ibid.Resources (Subject is indicated by URL – accessed 2 July 2011)http://en.wikipedia.org/wiki/Steeringhttp://www.usatoday.com/money/autos/2007-09-13-overloaded-cars_N.htm -8--------------------------------------------------------------------------------------------------------------------------------- IQPC GmbH | Friedrichstr. 94 | D-10117 Berlin, Germany t: +49 (0) 30 2091 3330 | f: +49 (0) 30 2091 3263 | e: eq@iqpc.de | w: www.iqpc.de Visit IQPC for a portfolio of topic-related events, congresses, seminars and conferences: www.iqpc.de
  9. 9. http://www.aa1car.com/library/steering_power_electric.htmhttps://docs.google.com/viewer?url=http://www.autoshop101.com/forms/Hybrid17.pdf&embedded=true&chrome=truehttp://www.indiacar.com/infobank/epc.htmhttp://www.nsxprime.com/FAQ/Technical/eps.htmhttp://www.carblogindia.com/electric-power-steering-vs-hydraulic-power-steering/http://www.eetimes.com/design/embedded/4006457/Electric-power-steering-one-good-turn-deserves-anotherhttp://auto.howstuffworks.com/steering5.htmhttp://en.wikipedia.org/wiki/Hydraulic_power_steeringliu.diva-portal.org/smash/get/diva2:23027/FULLTEXT01 -9--------------------------------------------------------------------------------------------------------------------------------- IQPC GmbH | Friedrichstr. 94 | D-10117 Berlin, Germany t: +49 (0) 30 2091 3330 | f: +49 (0) 30 2091 3263 | e: eq@iqpc.de | w: www.iqpc.de Visit IQPC for a portfolio of topic-related events, congresses, seminars and conferences: www.iqpc.de

×