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Message |
M. Hamill
Guest
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 Posted:
Thu Dec 08, 2005 8:33 am Post subject:
Question on hybrid cars |
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I don't own a hybrid, but have had a question about them on my mind:
We know that on hybrid cars like the Prius, during braking the battery is
recharged as the wheels act like generators. But I wonder about two things:
- Is there a conventional braking system pressing metal against metal as a
backup for these cars in case the generator function during braking doesn't
work properly; and
- If so, what kind of wear does this backup braking system endure, in
general (presumably far less than on conventional cars.)
Thanks in advance.
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Andrew Stephenson
Guest
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| Posted:
Thu Dec 08, 2005 9:19 am Post subject:
Re: Question on hybrid cars |
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In article <4bd43$4397a00b$d8442746$32274@FUSE.NET>
mhamill@fuse.net "M. Hamill" writes:
| Quote: | I don't own a hybrid, but have had a question about them on my mind:
We know that on hybrid cars like the Prius, during braking the battery is
recharged as the wheels act like generators. But I wonder about two things:
- Is there a conventional braking system pressing metal against metal as a
backup for these cars in case the generator function during braking doesn't
work properly; and
- If so, what kind of wear does this backup braking system endure, in
general (presumably far less than on conventional cars.)
|
I recently enquired of Toyota UK about the details of the Prius
braking system. Some of my comments have previously been posted
but here goes again...
The Prius subsystem which handles braking is a blend of electric
regenerative and conventional hydraulic technology.
As you tread on the brake pedal the system notes how you did so:
how hard; and how suddenly. From this, it works out (very fast)
what braking force is required. As much of this as possible is
provided by regenerative braking; the rest of done by hydraulic
braking (with the usual brake pads and such).
There are several useful benefits from this.
(a) If either of the available braking methods fails, the other
continues to provide some kind of slowing force. If the electric
side fails, I infer the hydraulic provides all of what's needed.
(b) Regarding your second question, I suppose that the brake pads
experience less wear, because regenerative braking is essentially
"non-contact" and will handle most of the low-force braking (such
as gentle touches on the pedal).
You should realise that much of the Prius is conventional. What
is new is how the old is blended with the new.
--
Andrew Stephenson |
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Ray O
Guest
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| Posted:
Thu Dec 08, 2005 9:19 am Post subject:
Re: Question on hybrid cars |
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"M. Hamill" <mhamill@fuse.net> wrote in message
news:4bd43$4397a00b$d8442746$32274@FUSE.NET...
| Quote: | I don't own a hybrid, but have had a question about them on my mind:
We know that on hybrid cars like the Prius, during braking the battery is
recharged as the wheels act like generators. But I wonder about two
things:
- Is there a conventional braking system pressing metal against metal as a
backup for these cars in case the generator function during braking
doesn't work properly; and
|
There is a conventional braking system but it is brake pad material against
metal, not metal against metal (unless you don't replace the pads after they
are worn).
| Quote: | - If so, what kind of wear does this backup braking system endure, in
general (presumably far less than on conventional cars.)
Thanks in advance.
|
The service brake would have the same or less wear than on a conventional
car.
--
Ray O
correct the return address punctuation to reply
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Guest
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| Posted:
Fri Dec 09, 2005 7:03 am Post subject:
Re: Question on hybrid cars |
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"Ray O" <rokigawa@tristarassociatesDOT.com> wrote in message
news:11bf5$4397a872$180fead6$27078@msgid.meganewsservers.com...
| Quote: |
"M. Hamill" <mhamill@fuse.net> wrote in message
news:4bd43$4397a00b$d8442746$32274@FUSE.NET...
I don't own a hybrid, but have had a question about them on my mind:
We know that on hybrid cars like the Prius, during braking the battery is
recharged as the wheels act like generators. But I wonder about two
things:
- Is there a conventional braking system pressing metal against metal as
a backup for these cars in case the generator function during braking
doesn't work properly; and
There is a conventional braking system but it is brake pad material
against metal, not metal against metal (unless you don't replace the pads
after they are worn).
- If so, what kind of wear does this backup braking system endure, in
general (presumably far less than on conventional cars.)
Thanks in advance.
The service brake would have the same or less wear than on a conventional
car.
--
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One follow up question, does it still have a conventional e-brake/ parking
brake on the Prius ? |
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Ray O
Guest
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| Posted:
Fri Dec 09, 2005 8:34 am Post subject:
Re: Question on hybrid cars |
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<reportspam@shaw.ca> wrote in message news:QJ4mf.74841$Gd6.9085@pd7tw3no...
| Quote: |
"Ray O" <rokigawa@tristarassociatesDOT.com> wrote in message
news:11bf5$4397a872$180fead6$27078@msgid.meganewsservers.com...
"M. Hamill" <mhamill@fuse.net> wrote in message
news:4bd43$4397a00b$d8442746$32274@FUSE.NET...
I don't own a hybrid, but have had a question about them on my mind:
We know that on hybrid cars like the Prius, during braking the battery
is recharged as the wheels act like generators. But I wonder about two
things:
- Is there a conventional braking system pressing metal against metal as
a backup for these cars in case the generator function during braking
doesn't work properly; and
There is a conventional braking system but it is brake pad material
against metal, not metal against metal (unless you don't replace the pads
after they are worn).
- If so, what kind of wear does this backup braking system endure, in
general (presumably far less than on conventional cars.)
Thanks in advance.
The service brake would have the same or less wear than on a conventional
car.
--
One follow up question, does it still have a conventional e-brake/ parking
brake on the Prius ?
I don't know but a conventional parking brake is the easiest way. By the |
way, passenger cars do not have an "emergency brake." They are called a
parking brake because they only apply the brakes to the rear wheels and will
not stop a vehicle as quickly as the service brake.
--
Ray O
correct the return address punctuation to reply |
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Andrew Stephenson
Guest
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| Posted:
Fri Dec 09, 2005 8:52 am Post subject:
Re: Question on hybrid cars |
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In article <QJ4mf.74841$Gd6.9085@pd7tw3no>
reportspam@shaw.ca "<reportspam@shaw.ca>" writes:
| Quote: | One follow up question, does it still have a conventional
e-brake/ parking brake on the Prius ?
|
The Prius does a good job of emulating a conventional automatic
gearshift car. On the dashboard is a button which has the same
effect as shifting the lever to Park. It locks the transaxle as
usual and is strong enough for level ground. The knob to select
[R]everse/[N]eutral/[D]rive (and new [B]attery-recharge option)
is just below this button, with functions lined up in the same
sequence as on a standard gear lever: imagine the arc which your
hand moves through during operation of a standard shift; the same
arc is followed in a Prius, just higher up at dashboard level.
Above the rest for your left foot is a easy-use foot brake that
engages a very normal mechanical brake. Forget to disengage this
and it obstructs your left foot; there is also a warning light.
--
Andrew Stephenson |
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Ray O
Guest
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| Posted:
Fri Dec 09, 2005 9:19 am Post subject:
Re: Question on hybrid cars |
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"Merritt Mullen" <mmullen8014@mchsi.com> wrote in message
news:mmullen8014-25DB75.20420908122005@netnews.asp.att.net...
| Quote: | In article <c6d24$4398edd8$180fead6$7774@msgid.meganewsservers.com>,
"Ray O" <rokigawa@tristarassociatesDOT.com> wrote:
I don't know but a conventional parking brake is the easiest way. By the
way, passenger cars do not have an "emergency brake." They are called a
parking brake because they only apply the brakes to the rear wheels and
will
not stop a vehicle as quickly as the service brake.
But in case of hydraulic failure, the mechanical "parking" brake will
still function as an emergency brake, correct? I've always called it an
"emergency" brake for that reason, and I do practice stopping the car with
it (comes from my training as a naval aviator, I guess).
Merritt
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Yes, in case of total hydraulic failure, the mechanical parking brake will
still function as an "emergency" brake but stopping distances will probably
be at least triple the distance with a normally functioning brake since the
front brakes do most of the braking. Nothing like the stopping power of a
tailhook though!
--
Ray O
correct the return address punctuation to reply |
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Merritt Mullen
Guest
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| Posted:
Fri Dec 09, 2005 9:19 am Post subject:
Re: Question on hybrid cars |
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In article <c6d24$4398edd8$180fead6$7774@msgid.meganewsservers.com>,
"Ray O" <rokigawa@tristarassociatesDOT.com> wrote:
| Quote: | I don't know but a conventional parking brake is the easiest way. By the
way, passenger cars do not have an "emergency brake." They are called a
parking brake because they only apply the brakes to the rear wheels and will
not stop a vehicle as quickly as the service brake.
|
But in case of hydraulic failure, the mechanical "parking" brake will
still function as an emergency brake, correct? I've always called it an
"emergency" brake for that reason, and I do practice stopping the car with
it (comes from my training as a naval aviator, I guess).
Merritt |
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Gary Eickmeier
Guest
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| Posted:
Sat Dec 10, 2005 12:48 am Post subject:
Re: Question on hybrid cars |
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Andrew Stephenson wrote:
| Quote: | The Prius does a good job of emulating a conventional automatic
gearshift car. On the dashboard is a button which has the same
effect as shifting the lever to Park. It locks the transaxle as
usual and is strong enough for level ground. The knob to select
[R]everse/[N]eutral/[D]rive (and new [B]attery-recharge option)
is just below this button, with functions lined up in the same
sequence as on a standard gear lever: imagine the arc which your
hand moves through during operation of a standard shift; the same
arc is followed in a Prius, just higher up at dashboard level.
|
The B position is an engine braking function. Seems to me its only
purpose is to help in long downhill runs, simulating a stick shift car
using the engine to back down a little.
Gary Eickmeier
New Owner |
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Andrew Stephenson
Guest
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| Posted:
Sat Dec 10, 2005 7:46 am Post subject:
Re: Question on hybrid cars |
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In article <Njkmf.21496$8d.12020@tornado.tampabay.rr.com>
geickmei@tampabay.rr.com "Gary Eickmeier" writes:
| Quote: | Andrew Stephenson wrote:
The Prius does a good job of emulating a conventional automatic
gearshift car. On the dashboard is a button which has the same
effect as shifting the lever to Park. It locks the transaxle as
usual and is strong enough for level ground. The knob to select
[R]everse/[N]eutral/[D]rive (and new [B]attery-recharge option)
is just below this button, with functions lined up in the same
sequence as on a standard gear lever: imagine the arc which your
hand moves through during operation of a standard shift; the same
arc is followed in a Prius, just higher up at dashboard level.
The B position is an engine braking function. Seems to me its only
purpose is to help in long downhill runs, simulating a stick shift car
using the engine to back down a little.
|
Not to be picky, actually it is touted as an optional instruction
to the car to charge the battery using regenerative braking. The
driver will be in a better position to know the road ahead so can
tell the car to recharge (and, incidentally, slow down). Most of
the time, I find this function of little use; but it's nice to be
able to choose. As it happens, I do employ it most to apply some
e-braking where foot-braking is not essential; but that certainly
is not its primary function. Start relying on it and one day you
may find the battery can't take more charge -- then braking won't
be as hard as hoped and you suddenly have to f-brake anyhow. <g>
At least, all of the above is based on recollections of a tedious
trawl through the handbook, as well as general Toyota propaganda.
--
Andrew Stephenson |
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Brent Secombe
Guest
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| Posted:
Mon Dec 12, 2005 1:28 am Post subject:
Re: Question on hybrid cars |
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In article <DrXmf.4910$md.2708@tornado.tampabay.rr.com>, Gary Eickmeier
<geickmei@tampabay.rr.com> wrote:
| Quote: | Andrew Stephenson wrote:
Not to be picky, actually it is touted as an optional instruction
to the car to charge the battery using regenerative braking. The
driver will be in a better position to know the road ahead so can
tell the car to recharge (and, incidentally, slow down). Most of
the time, I find this function of little use; but it's nice to be
able to choose. As it happens, I do employ it most to apply some
e-braking where foot-braking is not essential; but that certainly
is not its primary function. Start relying on it and one day you
may find the battery can't take more charge -- then braking won't
be as hard as hoped and you suddenly have to f-brake anyhow. <g
That can't be right. We all know that the Prius regenerates power
whenever you back off the accelerator. The book also mentions that the B
function shouldn't be used as a practice, because it will get poorer gas
mileage. I see the only purpose as engine braking, but then I am a new
owner (a week or so).
|
Welcome, Gary. I forescast ou'll be driving with a smile. I am.
In hilly terrain I use the B setting in lieu of braking on steep
downslopes. Else, I leave it alone. The problem with using B for
slowing in traffic is that it doesn't trigger the brake lights.
The hypnotic energy-transfer animation shows that even on level ground
the gas engine periodically charges the main battery. The book's advice
against using B applies to travel on level ground where indeed the
practice does reduce the gas mileage.
Brent |
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