Vacuume brake booster

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offgridQLD
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Vacuume brake booster

Post by offgridQLD »

I was driving the Imiev today through a shopping center car park. Rolling along at just 10 - 20 kph trying to find a park. The window was down and The car was so quiet at very low speeds. I could actually hear the sound as every section of the rubber tread pattern flexed and squelched as It contacted the pavement while I gently turned. As I slowed gently for the car in front to park the peacefulness was rudely interrupted by BZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZT ! The vacuum pump buzzing away. It's the one thing that spoils the EV experience.

It made me think it's really the only thing on the car that makes any noise. I wonder if it's just a throwback from the good old days. Vacuum was always there in abundance with a ICE running. The Imiev was originally a ICE car so I guess the vacuum booster was retained.

What about ground up EV builds like the I3 and Model S do they use a vacuum booster for power assisted braking?

There has to be a better way to achieve the same results especially with OEM EV's.

Ideas for power assisted braking without using a traditional vacuum booster that's totally silent and maybe even more reliable.

What about some kind of electromagnetic booster for power assisted braking?


Kurt
Last edited by offgridQLD on Tue, 05 May 2015, 09:06, edited 1 time in total.
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Johny
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Vacuume brake booster

Post by Johny »

Unfortunately hot rodders, diesels and any car hobbiest that has turbo boosted a car uses electric-vacuum assist - so it has precedence.
There are alternatives. My car has 9" discs but no booster - it does need two feet on the pedal to pull up quickly though.

Engineered Components, Inc. introduces its new Universal Brake Assist. This new brake booster system takes assisted braking to a new level of performance without the use of any external assistance. The Universal Brake Assist is a completely self contained system that requires no vacuum, no hydraulic pressure, and no electrical power. Brake pedal input force is increased using a unique combination of both hydraulic and mechanical systems to increase the master cylinder pushrod force by 75%. Used in conjunction with the supplied master cylinder the Universal Brake Assist yields a 100% increase in system pressure compared to typical unboosted 1 inch bore master cylinder, and unlike a vacuum booster the Universal Brake Assist does not reach a “saturation point,” but continues to provide a linear increase in pushrod force with increasing pedal force. An additional safety feature is a 100% fail-safe system providing manual backup in the event of unit or master cylinder failure.


https://www.hotrodhotline.com/engineere ... Ug1J46qpHw

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Last edited by Johny on Tue, 05 May 2015, 09:19, edited 1 time in total.
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offgridQLD
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Vacuume brake booster

Post by offgridQLD »

Yes Johny,

Thats most likely the way they will go for a while. Just due to the fact the parts are available and they work. Even if there is a better way.

The totally mechanical system looks interesting.

I kind of know why they like vacuum systems (other than ICE cars make vacuum) There is the redundancy of the stored vacuum even if the cars engine or electric pump didn't work you get one or two boost assisted stops.

I guess an electrically assisted brake force system could have some kind of capacitor to act as a redundancy if it lost power.

Kurt

mikedufty
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Vacuume brake booster

Post by mikedufty »

They manage hugely powerful one finger braking systems on motorcycles without power assistance. You'd think it would be possible to make a reasonable one foot operated system on a car. I guess car brake pads are expected to last a lot longer though.

I suspect the vacuum assist is a bit like the electric heating instead of reverse cycle aircon, just not a lot of effort put into replacing something that has been used on ICE cars because it was there.

Does the Tesla use vacuum for brake assistance?
reecho
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Vacuume brake booster

Post by reecho »

Tesla did use vacuum pumps initially but have now migrated to full electronic over hydraulic in lieu of autopilot...
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Richo
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Vacuume brake booster

Post by Richo »

Found this on a hot rodders forum from a couple of years ago regarding it:
raycrow wrote:Smells like snake oil to me.
There is no free lunch.
If you are getting increased hydraulic pressure for the same amount of pedal force, you are paying for it with increased pedal travel.
So the short answer is NO but the long answer is YES.
Help prevent road rage - get outta my way!
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offgridQLD
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Vacuume brake booster

Post by offgridQLD »

So with the tesla model S. Is that electric motor driven hydraulic pump or more like a electric trailer brake using a magnetic actuator's.?

Kurt
Last edited by offgridQLD on Tue, 05 May 2015, 11:25, edited 1 time in total.
reecho
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Vacuume brake booster

Post by reecho »

Same setup as Nissan Leaf I believe.....electric pump creates pressure for hydraulic circuit
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Richo
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Vacuume brake booster

Post by Richo »

This one uses an electric motor to "add" the braking power hydraulically - no vacuum.
It says it's quieter than the fuel pumps.
http://www.abspowerbrake.com/ehpm.html
So the short answer is NO but the long answer is YES.
Help prevent road rage - get outta my way!
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offgridQLD
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Vacuume brake booster

Post by offgridQLD »

Well if its silent then it's got to be better than a electric vacume pump.That said some aftermarket external fuel pumps are very noisy so it could be just as loud as a electric vacume pump. I would prefer some kind of progressive magnetic actuator that assisted .

I think the one on the imiev makes more noise than a modern small ICE car at idle. Given its high pitched noise that is very directional.

Kurt
Last edited by offgridQLD on Tue, 05 May 2015, 12:17, edited 1 time in total.
TooQik
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Vacuume brake booster

Post by TooQik »

If you want good brakes with no vacuum or noise, just go the racing route and put in a pedal box similar to the following:

AP Racing Pedal Boxes

The added benefit is you can balance your brakes front/rear more effectively, which would be handy for anyone playing with regen.

I personally haven't used a car with this kind of setup and have opted for a vacuum pump at this stage for my build, but it is something I am considering down the track. How long it takes me will depend on how noisy my pump is I guess. Image
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