2009-05-18 02:17:21 UTC
Thanks for your inputs regarding noise requirements for an EV.
We have in fact two conflicting requirements:
- A very low level of noise is a wonderful quality of the EV technology,
both for passengers and for people who live near a street or highway.
- There is a need for sound generation as an attention getter for
pedestrians, and mostly in urban traffic.
Here are some ideas:
External sound (not noise..) generation would be desirable at very low
to low speeds, when we are most likely to be in urban driving conditions
and in the presence of people. I say sound and not noise since we
generally associate noise with an unpleasant perception. Some sounds can
even be pleasant!
High speed driving does not need sound generation since the road noise
generated by the tires is always present above 30 - 40 miles/hour.
At low speed, it would be nice to to generate a sound that would be a
warning for pedestrians without being annoying or nerve racking. This
can be easily achieved with a wave generator (or recording), and with a
classic (relatively low power) audio amplifier, associated with a
waterproof speaker located outside the cabin. We should be able to
control what sound we emit and the level of the sound. The sound
generation should be triggered by the speedometer of the car, or the
RPM of the motor depending of what is available (or feasible). I predict
that one day this sound generation will become a mandatory safety
feature for EV's, with levels and sound patterns having to meet safety
specifications (to be determined).
I have already planned to implement an external sound system in my new
EV.. (I will even be able to play Harley Davidson or Maserati engine
noises if I want to attract attention!!)
Here is my experience with back-up alarms: during my first driving test,
when I backed up, my wife was not looking at the car, and although I was
looking at her and there was no danger, she became really alarmed since
she did not hear anything! She insisted that I install a back-up beeper
alarm. I was very lucky to find a minuscule beeper that needs NO wiring
at all and that sticks directly to the back-up lights: it receives its
power through a photocell directly from the light emitted by the backup
bulb shining through the plastic lens! It provides a fairly loud alarm
to people within a radius of 20 feet. I paid $6.00 at PEP Boys (SKU No.
As far as cabin noise is concerned, I just installed the vacuum pump for
my power brake and I was shocked by the very loud rattle it produces.
This is obnoxious: I am very disappointed to see that the best pump I
could find (made by Thomas) is so noisy, and that the pump runs every
time I use the brakes! If we expect to have a widespread EV acceptance,
I estimate that this noise is unacceptable!
Is there anyone in our EV community who could recommend a more silent
pump and who could tell me if increasing the vacuum reservoir capacity
would avoid triggering the pump at every braking occasion? How are the
current plug-in EV's designed (I have never heard them making rattling
noises!). What about the other electric conversions like EV1, RAV4?
Neon 2000 EV
Subject: [EVDL] Noise is valuable for safety of pedestrians
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Noise is valuable for safety of pedestrians near EVs
A noisy vacuum pump should be considered an asset,(as Lawrence Rhodes has
said, and I agree.) not a detriment. So too squeaky brakes, so why not bend
the brass strip or pad wear alarm / indicator closer to the disk so even
new brake pads make that attention getting, ?Squeal.? Or you might consider
adding a ?Backup Alarm? module connected to the brake light switch and a
five second delay cutoff relay (Or 555 timer circuit?) so it doesn't ping
incessantly at the traffic light. Additionally, the brake lights can
connect to the front turn lamps, as many California cars do, to alert oncoming
drivers of your slowing. (Note to California drivers, other States do not
require this feature?) IMHO these low impact modifications may increase
SAFETY, and none are Illegal or mandated at this time, IMHO ! As I see it, we
want to be noticed by anyone who might be thereby deterred from entering
our space, lessening the likelihood of collision with vehicles or pedestrians.
The benefit to you and me would be no need to wait for 30 minutes or more
for investigating police to make a report and less wear on our "Emergency
Electric Vehicle Training Center Inc.
Training you, to fix Tomorrows Electric Vehicles.
Dennis L. Miles Director