Brakes, clutch, sus­pen­sion

Motor Equipment News - - CONTENT - By John Ox­ley

There’s e’s lots of talk about elec­tric ve­hi­cles cles (EVs) and plug-in EVs (PHEVs), EVs), hy­brids, and hy­dro­gen cars – all sorts of ways to try to al­ter the amount of car­bon diox­ide be­ing charged ged into the at­mos­phere – and while e all of th­ese will un­doubt­edly present ent chal­lenges for the mo­tor tech­ni­cian, nician, there are three ar­eas where re there has been lit­tle change in the past 100 years. You got it: brakes, clutch ch and sus­pen­sion.

If you’re ou’re talk­ing a per­for­mance ve­hi­cle, cle, or one mod­i­fied to give ex­tra per­for­mance, or­mance, well the for­mula is sim­ple: le: stop the car in the short­est pos­si­ble ible time, re­peat­edly; get the power er from the en­gine to the gear­box as smoothly moothly as pos­si­ble, without burn­ing ing out the clutch; and fi­nally, keep p the wheels as square to the ground nd as pos­si­ble, without lift­ing wheels els so power is lost.

Hav­ing ving said this, there ARE con­tin­u­ous nu­ous de­vel­op­ments de­signed to make e all three of th­ese vi­tal ele­ments in the e drive train work bet­ter, so we had a look at what’s hap­pen­ing.

BRAKES

AKES For ev­ery­day driv­ing, the most im­por­tant or­tant new de­vel­op­ment is re­gen­er­a­tive brak­ing. This was de­vel­oped to use the ki­netic en­ergy re­leased when a car is braked to gen­er­ate elec­tri­cal power. Most peo­ple think this only ap­plies to EVs, PHEVs and hy­brids, but in fact for some time now man­u­fac­tur­ers have been us­ing this to re­place the al­ter­na­tor and other an­cil­lar­ies nor­mally driven by en­gine-gen­er­ated elec­tri­cal en­ergy, thus cut­ting down on power loss “stolen” from the en­gine, re­sult­ing in bet­ter econ­omy.

At the same time the reg­u­lar brakes are still re­tained (for when you want to stop re­ally quickly); the trick is to man­age both sys­tems so they work op­ti­mally.

Nis­san’s Elec­tric Driven In­tel­li­gent Brake is a prime ex­am­ple of this lat­est tech­nol­ogy.

Nis­san says the EDIB (Elec­tric Driven In­tel­li­gent Brake) al­lows and con­trols op­ti­mi­sa­tion of the re­gen­er­a­tive brake and reg­u­lar fric­tion brake (hy­draulic brake).

After step­ping on the brake pedal, the sys­tem pro­duces nat­u­ral and ad­e­quate brak­ing force that cor­re­sponds to the op­er­a­tion. The amount of en­ergy re­gen­er­a­tion also needs to be in­creased as much as pos­si­ble.

EDIB (Elec­tric Driven In­tel­li­gent Brake) con­trols the re­gen­er­a­tive brake and fric­tion brake to sup­port both of th­ese re­quire­ments. re­quire­ments Fur­ther Fur­ther, it also con­trols the re­ac­tive force from the pedal in or­der to unify the feel­ing when step­ping down on the pedal and the sense of de­cel­er­a­tion.

When the driver steps on the brake pedal, the stroke sen­sor de­tects op­er­a­tion of the brake. That in­for­ma­tion is com­mu­ni­cated to the ECU and con­trols the mo­tor. The mo­tor en­gages the pis­ton and am­pli­fies the fric­tion brake’s pres­sure (hy­draulic pres­sure). Through op­ti­mum con­trol of the fric­tion brake’s hy­draulic pres­sure, the en­ergy re­gen­er­a­tion out­come is max­imised.

An­other de­vel­op­ment is brakeby-wire and elec­tronic park­ing brake tech­nol­ogy.

Brembo is a com­pany usu­ally as­so­ci­ated with per­for­mance brak­ing sys­tems, but at the Frank­furt Mo­tor Show last month the com­pany showed sys­tems tar­geted at im­prov­ing driv­ing com­fort, re­duc­ing the num­ber of brak­ing sys­tem com­po­nents, en­hanc­ing per­for­mance and in­creas­ing safety re­sult­ing in seam­less op­er­a­tion un­der any con­di­tions.

Brembo says it is achiev­ing ad­vanced re­sults as it pi­o­neers its new brake-by­wire tech­nol­ogy, in­clud­ing at­tain­ing a time-to-lock re­sponse of close to 100 mil­lisec­onds, com­pared to 300-500 with tra­di­tional hy­draulic brakes. This highly re­spon­sive per­for­mance makes the sys­tem ap­pro­pri­ate for the cur­rent mar­ket de­mand for au­ton­o­mous brak­ing.

Brembo has also been suc­cess­ful in in­te­grat­ing a brake cal­liper and park­ing brake, com­bined into one alu­minium unit, known as an Elec­tric Com­bined Monobloc. This break­through tech­nol­ogy elim­i­nates com­po­nents and in­te­grates the brak­ing sys­tem with the ve­hi­cles elec­tron­ics for smooth and ef­fort­less op­er­a­tion to se­cure the ve­hi­cle while parked thus re­duc­ing part com­plex­ity and un­sprung weight.

The Brembo range of elec­tronic park­ing brak­ing of­fer­ings is com­prised of Elec­tric Com­bined Monobloc, Elec­tric Park­ing brake, and Elec­trome­chan­i­cal Com­bined Slid­ing brake.

In or­der to en­sure high safety mar­gins in emer­gency sit­u­a­tions, Brembo has de­vel­oped and fine-tuned mon­i­tor­ing soft­ware that ac­ti­vates dy­namic brak­ing. In the event that both of the cal­lipers’ hy­draulic cir­cuits should fail to op­er­ate, the driver can still stop the car by us­ing the elec­trome­chan­i­cal ac­tu­a­tor.

The new Brembo cal­liper also has a hot-brake reclamp fea­ture. This means that when the ve­hi­cle is parked on a slope, the soft­ware au­to­mat­i­cally reclamps the cal­liper to ac­count for the ther­mal de­for­ma­tion of the disc and pads, guar­an­tee­ing the safe park­ing of the car on the steep­est slopes at very high tem­per­a­tures.

CLUTCH

De­vel­op­ments in clutches con­tinue apace, de­spite that the trend glob­ally is to switch to some sort of au­to­matic or semi-au­to­matic gear­box as peo­ple get lazier, roads more con­stricted, and elec­tron­ics make auto ‘boxes, es­pe­cially CVH and dou­ble clutch, as eco­nom­i­cal as man­u­als.

On the reg­u­lar clutch front, par­tic­u­lar men­tion should be made of Aus­tralian Clutch, Exedy and Ter­rain Tamer, whose con­stant de­vel­op­ments to pro­duce world-class re­place­ments for high per­for­mance, com­pe­ti­tion, and heavy duty 4x4 use are well doc­u­mented in this mag­a­zine.

How­ever, when it comes to pro­duc­tion cars, it’s worth tak­ing a look at de­vel­op­ments from Honda. Reg­u­lar dual clutch gear­boxes have two clutches (nat­u­rally) and ei­ther six or seven speeds. Honda, though, has gone a few stages fur­ther.

We all know that dual clutch trans­mis­sions (DCT) can be awk­ward in tight spa­ces, where small pedal move­ments can make them jerky, and a num­ber of car­mak­ers have al­ready

in­tro­duced small torque con­vert­ers into the driv­e­line to help solve this, no­tably Subaru and Nis­san.

Honda has done the same, but in an eight-speed trans­mis­sion, and claims in­cor­po­rat­ing a torque con­verter into the unit not only pro­vides in­ter­nal NVH ben­e­fits that help de­liver the low-speed re­fine­ment most driv­ers seek, but its in­her­ent torque mul­ti­pli­ca­tion boosts offthe-line ac­cel­er­a­tion.

The torque con­verter is more ex­pen­sive than a clutch for the same ap­pli­ca­tion. But nor­mal DCT clutches de­mand use of a more costly dual-mass fly­wheel, so the torque con­verter so­lu­tion is no more ex­pen­sive over­all, ac­cord­ing to Honda. But that’s not where it stops. Ac­cord­ing to Au­to­car mag­a­zine, Honda has patented a de­sign for an 11-speed DCT with no fewer than three clutches (which we sup­pose would means it’s a TCT).

The patent’s de­scrip­tion claims the ad­di­tion of the third clutch would de­crease the loss of torque ex­pe­ri­enced be­tween gear shifts in dual clutch gear­boxes. The triple clutch would also mean quicker gearshifts than a dual clutch.

The bad news? Honda says it hasn’t any plans for the new gear­box yet!

SUS­PEN­SION

For the or­di­nary fam­ily car – as well as the ma­jor­ity of per­for­mance cars – sus­pen­sion very much re­lies on a com­bi­na­tion of coil springs, sus­pen­sion arms, and shock ab­sorbers, with anti-roll bars and some trick add-ons to make them more pre­cise and ef­fec­tive, while the use of alu­minium al­loy is in­creas­ing in a bid to cut down on un­sprung weight.

How­ever, th­ese days sus­pen­sion re­fine­ment has be­come some­thing of an art form, par­tic­u­larly among pre­mium car man­u­fac­tur­ers, and like any­thing else, this is slowly trick­ling down the ranks. The driver is able to make on-the-move changes to sus­pen­sion char­ac­ter­is­tics to make them ei­ther more com­fort­able or sportier, and we’re see­ing this more and more of­ten.

How­ever, that still re­lies on a tra­di­tional sus­pen­sion lay­out, with the changes made mainly to the shock ab­sorbers to ef­fect change the ride and han­dling.

But there have been other suc­cess­ful de­vel­op­ments. For in­stance. over the years we have seen great ad­vances in the use of air sus­pen­sion, par­tic­u­larly in SUVs de­signed to go off-road, while a few years ago Lo­tus played with a to­tally ac­tive sus­pen­sion which did away with springs al­to­gether.

And this lat­ter is still the Holy Grail of sus­pen­sion man­age­ment.

Audi has al­ready gone a long way in this re­gard with its lat­est SQ7 SUV, which cor­ners flat­ter than many sports cars, while still re­tain­ing a high­ish stance on the road, and the abil­ity to go off-road if re­quired. It uses a sys­tem called Elec­trome­chan­i­cal Ac­tive Roll Con­trol, de­vel­oped by Scha­ef­fler.

At each axle, front and rear, a com­pact elec­tric mo­tor with a three­stage plan­e­tary gear set sep­a­rates the two halves of the sta­biliser. On an un­even road sur­face, they are de­cou­pled from one an­other, thus im­prov­ing body roll char­ac­ter­is­tics.

With a sportier driv­ing style, how­ever, the tubes are twisted smoothly in op­pos­ing di­rec­tions. The car rolls less on bends, lat­eral in­cli­na­tion is markedly re­duced and the ten­dency to un­der­steer is kept even bet­ter in check. This en­ables higher lat­eral ac­cel­er­a­tion and thus faster cor­ner­ing.

Honda’s lat­est eight-speed dual clutch trans­mis­sion.

The Scha­ef­fler-de­vel­oped Elec­trome­chan­i­cal Ac­tive Roll Con­trol used in the Audi SQ7.

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