RE: What is a clutch-by-wire system? PH Explains

RE: What is a clutch-by-wire system? PH Explains

Tuesday 16th October 2018

What is a clutch-by-wire system? PH Explains

How doing away with cables and hydraulics can grant improved efficiency and enable more assistance features



A 'clutch-by-wire' system is one that does away with the mechanical or hydraulic connection between the clutch pedal and clutch itself.

Instead, the position of the clutch pedal is monitored by sensors and an electromechanical actuator is used to remotely operate the clutch.

Consequently, in a car equipped with a 'CBW' system, the driver is presented with a familiar-looking pedal and transmission arrangement - and the car otherwise drives just like any other manual transmission-equipped vehicle.

However, the CBW system can also automatically operate the clutch or alter the behaviour of its actuation. This automatic clutch control capability grants a wide range of additional safety, efficiency and assistance benefits.

For example, automotive CBW systems - such as those unveiled by Bosch in 2013 and ZF in 2015 - can automate clutch control at low speeds. This means the driver can creep in traffic, in first gear, without having to operate the clutch.


How do clutch-by-wire systems work?

In a clutch-by-wire set-up, the pedal assembly is replaced with one that features a sensor which monitors the pedal position - just like the pedal assemblies used in many electronically controlled throttle systems.

Signals from the pedal are then transmitted to a control unit which triggers the electrically driven actuator that operates the clutch. Because there is no direct link between the pedal and the clutch, the overseeing control system can ensure that the driver's inputs are translated into the most appropriate clutch action.

If a driver were to release the clutch pedal too quickly, for example, the overseeing control system can slow the engagement of the clutch - preventing judder, lurching or a stall.

A further benefit of such a configuration is that the pedal travel and clutch actuation will remain consistent throughout the life of the clutch, as the actuator can automatically take up any slack caused by wear in the system.

Similarly, the use of CBW also makes it easier to integrate hybrid technology into a conventional manual transmission-equipped car - which can help keep costs down while boosting efficiency.


What are the benefits of a clutch-by-wire system?

The motivation behind developing clutch-by-wire systems was one of cost and functionality. A manual transmission with a CBW reportedly costs 50 per cent less than a conventional torque converter-based automatic while offering many similar advantages - such as the ability to coast with the engine off and reduced driver workload.

German manufacturer Schaeffler claims its CBW system, among other benefits, can reduce fuel consumption and CO2 emissions by up to 10 per cent thanks to the coasting function alone. This enables the engine to be automatically decoupled from the transmission, and then shut off, when the car is coasting - reducing fuel consumption.

There are also myriad assistance-related functions which are enabled by CBW systems, including an anti-stall feature, complete clutch automation at low speeds and emergency braking aids. The behaviour of the clutch could also be altered depending on the conditions.

One of the potential pitfalls, however, is the potential lack of meaningful feedback through the pedal - which has been a reported issue with prototype CBW setups, as well as other similar 'X-by-wire' systems. The pedal itself could be engineered to deliver suitable feedback, though, in order to emulate the feel of a conventional hydraulic assembly.

CBW systems have seemingly met with little success so far, though, perhaps due to ever-advancing, increasingly inexpensive fully automatic transmissions and more efficient engines. That said, some manufacturers - such as GM - are beginning to develop and test their own systems. As safety and efficiency demands continue to rise, some may subsequently start to use CBW set-ups in their vehicles.

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Author
Discussion

Spaceibiza

Original Poster:

31 posts

57 months

Tuesday 16th October 2018
quotequote all
If they can get the feedback sorted, it sounds like a good idea to me. Best of both worlds. All the involvement of a manual 3 pedal setup, but then when you get stuck in mega traffic jam, you can creep along just like an auto.

NDNDNDND

780 posts

130 months

Tuesday 16th October 2018
quotequote all
I'll bet, in reality, this will be completely horrible to use.

It's bad enough how numb, electric steering systems try to override your inputs, the same for throttle and brake by wire, not to mention electronic handbrakes, and now a clutch you have to second-guess too!

As ever, the lowest-common-denominator rules. All cars are being built to favour the clumsiest and least competent, and everyone else must suffer being patronised too.


TegTypeR

69 posts

79 months

Tuesday 16th October 2018
quotequote all
Idea is sound but in reality it's another sensor to go wrong, another piece of electronics to disable the vehicle, another "driver aid" to make the driving experience more remote.

As a previous poster has said, it's like electric power steering, electronic hand brakes and another who host of automated systems that have been crammed in to vehicles recently, which allegedly make our driving experience easier but in reality frustrate and annoy the driver ever more.

And before anyone comments that electronic systems are far more reliable and less likely to strand a driver, recently I have had an electronic hand brake switch disintegrate - disabling the car, a Mercedes electronic key / ignition switch completely fail - disabling the car, and a throttle sensor fail - disabling the car. In 27 years of driving I have never had a manual handbrake, metal key or cable throttle issue that has stranded me or indeed has cost me the money these three have.

Also, surely clutch control is one of the key things for learning to drive in the first place. With a system like this, the learner will not be learning. Gone will be the kangaroo starts, stalled hill starts and engine running emergency stops, which to me seems like another chunk out of the skill of driving for the younger generation.

Low Pro

161 posts

108 months

Tuesday 16th October 2018
quotequote all
Try double de clutching on this bad boy wobble

Matthen

1,080 posts

98 months

Tuesday 16th October 2018
quotequote all
Yet another way to take the fun out of driving. I cannot imagine how annoying it would be for my clutch pedal to decide that my engagement was too exuberant, and do what it likes instead. Forget it, may as well go full auto.

PositronicRay

16,815 posts

130 months

Tuesday 16th October 2018
quotequote all
Low Pro said:
Try double de clutching on this bad boy wobble
I don't see why you shouldn't, anyway it'll give them a good excuse to invent synchromesh.

TooMany2cvs

29,008 posts

73 months

Tuesday 16th October 2018
quotequote all
Isn't this actually a step back from well-established technology?

All those robotised-manual semi-autos that have been common for the last decade/decade and a half? The only difference here is that the driver's explicitly telling the clutch what to do, not the ECU deciding it.

And if you don't get hung up on "electronics", just an automated disconnect between direct operation from pedal to clutch, then how about the Citroen DS hydraulic box in the mid 50s?

Mackofthejungle

843 posts

142 months

Tuesday 16th October 2018
quotequote all
Just sounds pointless. I don't see why you'd have one. If you're not interested in having a manual then get an automatic - a dual clutch or regular - they're superb. If you want a manual, why on earth would you want all this gubbins? Creep in traffic? A properly thought out manual gives you this! Instead of designing every set of ratios to give ideal 0-60 times (who fking cares) and to pass nonsensical emissions programs, give us a 1st gear that creeps at tickover at 3mph. and 2nd at 5mph, and 3rd at 10. Like my old cars used to do before this ridiculous economy gearing was introduced.

Give us a nice long 6th/7th gear of cruising, but make the rest of them useful for goodness sake.

Just a faff in my opinion. Surely less efficient too. I've already got a leg, why wouldn't I use it?

thatdude

2,079 posts

74 months

Tuesday 16th October 2018
quotequote all
NDNDNDND said:
I'll bet, in reality, this will be completely horrible to use.

It's bad enough how numb, electric steering systems try to override your inputs, the same for throttle and brake by wire, not to mention electronic handbrakes, and now a clutch you have to second-guess too!

As ever, the lowest-common-denominator rules. All cars are being built to favour the clumsiest and least competent, and everyone else must suffer being patronised too.
I agree.

Why couldnt they keep on with carburettors? And whats with modern ignition systems? Even nowadays you get hese fangled multi-grade oils. And windscreen wipers! And air conditioning! What's wrong with opening a bloody window!

Haltamer

1,093 posts

27 months

Tuesday 16th October 2018
quotequote all
Mackofthejungle said:
Instead of designing every set of ratios to give ideal 0-60 times (who fking cares) and to pass nonsensical emissions programs, give us a 1st gear that creeps at tickover at 3mph. and 2nd at 5mph, and 3rd at 10. Like my old cars used to do before this ridiculous economy gearing was introduced.
You just need a smaller engine, and less torque biggrin
My 1.4 Will happily lurch slowly onwards at 4mph in 1st, and 6mph in 2nd

PositronicRay

16,815 posts

130 months

Tuesday 16th October 2018
quotequote all
Haltamer said:
Mackofthejungle said:
Instead of designing every set of ratios to give ideal 0-60 times (who fking cares) and to pass nonsensical emissions programs, give us a 1st gear that creeps at tickover at 3mph. and 2nd at 5mph, and 3rd at 10. Like my old cars used to do before this ridiculous economy gearing was introduced.
You just need a smaller engine, and less torque biggrin
My 1.4 Will happily lurch slowly onwards at 4mph in 1st, and 6mph in 2nd
A short 1st gear is horrible, pulling out of a junction you find yourself wanting 2nd while still steering.

buggalugs

8,571 posts

184 months

Tuesday 16th October 2018
quotequote all
As well as being 50% cheaper I bet these will reduce clutch based warranty claims too.

cookie1600

1,300 posts

108 months

Tuesday 16th October 2018
quotequote all
I thought that was what the left leg was invented for?

Can't see any reason at all to integrate this into a car. Full auto or hydraulic/cable manual thank you.

annodomini2

5,813 posts

198 months

Tuesday 16th October 2018
quotequote all
buggalugs said:
As well as being 50% cheaper I bet these will reduce clutch based warranty claims too.
Doubt it, they'll be used to fit cheaper clutch setups, just like DMF's are used to fit a cheaper Gearbox.

havoc

24,636 posts

182 months

Tuesday 16th October 2018
quotequote all
PositronicRay said:
Haltamer said:
Mackofthejungle said:
Instead of designing every set of ratios to give ideal 0-60 times (who fking cares) and to pass nonsensical emissions programs, give us a 1st gear that creeps at tickover at 3mph. and 2nd at 5mph, and 3rd at 10. Like my old cars used to do before this ridiculous economy gearing was introduced.
You just need a smaller engine, and less torque biggrin
My 1.4 Will happily lurch slowly onwards at 4mph in 1st, and 6mph in 2nd
A short 1st gear is horrible, pulling out of a junction you find yourself wanting 2nd while still steering.
So what you need is an engine that behaves well at very low revs (+/- 1,000), has a broad enough power-band to deliver a sensible top-end to 1st (e.g. >20mph without feeling strangled), and a clutch that's comfortable and feelsome enough to modulate.

To me that says nat-asp petrol engine, ideally with either big-cubes or some form of variable-valve-lift. Oh dear, they don't make them anymore because of emissions! banghead

Haltamer

1,093 posts

27 months

Tuesday 16th October 2018
quotequote all
havoc said:
PositronicRay said:
Haltamer said:
Mackofthejungle said:
Instead of designing every set of ratios to give ideal 0-60 times (who fking cares) and to pass nonsensical emissions programs, give us a 1st gear that creeps at tickover at 3mph. and 2nd at 5mph, and 3rd at 10. Like my old cars used to do before this ridiculous economy gearing was introduced.
You just need a smaller engine, and less torque biggrin
My 1.4 Will happily lurch slowly onwards at 4mph in 1st, and 6mph in 2nd
A short 1st gear is horrible, pulling out of a junction you find yourself wanting 2nd while still steering.
So what you need is an engine that behaves well at very low revs (+/- 1,000), has a broad enough power-band to deliver a sensible top-end to 1st (e.g. >20mph without feeling strangled), and a clutch that's comfortable and feelsome enough to modulate.

To me that says nat-asp petrol engine, ideally with either big-cubes or some form of variable-valve-lift. Oh dear, they don't make them anymore because of emissions! banghead
It's a 1.4 Honda iVTEC NA - First finishes off at 30, But beyond 20 is not exactly subtle.
Ticks most of those boxes!

As for my opinion on clutch by wire, I wouldn't mind - This could play in perfectly with the modes that manufacturers tend towards now, with a smoothed mode for regular operation, and a "natural" mode for direct control of the clutch without nannying.
Surely this would even allow for semi automatic shifting; Just pop the shifter from n to n and the automatic clutch could do the rest, which might prove a nice relief in clutch pumping traffic.

HRCM

67 posts

36 months

Tuesday 16th October 2018
quotequote all
Cadence clutching could be an issue tongue out

Haltamer

1,093 posts

27 months

Tuesday 16th October 2018
quotequote all
HRCM said:
Cadence clutching could be an issue tongue out
Never! It could be automated away:
Automated Cadence Clutching System

yes

tgx

91 posts

97 months

Tuesday 16th October 2018
quotequote all
"easier to integrate hybrid technology"

This is the reason for all of these 'by wire' systems.
The object is to eventually remove the driver. Having a system
that is easily controlled by computers is the first step.

Teddy Lop

1,844 posts

14 months

Tuesday 16th October 2018
quotequote all
why even bother having the 3rd pedal then if the systems using it as a measure of intent and deciding itself if you're doing it right?

Autos and manuals are both great and both have their place and so too would a hybrid transmission (servo on clutch with automatic functionality, but full manual control for when you want it) but a dummy clutch pedal seems like the stupidest idea ever, the driver is essentially becoming maggie in the simpsons opening credits and pretending to perform a function thats actually automated... next you'll be telling cars have fake piped engine noise.