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From: Ray O on 11 Feb 2010 13:01

"Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message
news:hl1fv0$56m$1(a)news.eternal-september.org...
>
> "C. E. White" <cewhite3(a)mindspring.com> wrote in message
> news:hl19j0$a23$1(a)news.eternal-september.org...
>>
>> "Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote in message
>> news:hl0652$kug$1(a)news.eternal-september.org...
>>>
>>> "Austin Toyota Club" <Austin Texas> wrote in message
>>> news:Z62dnRpLHd0u6-7WnZ2dnUVZ_vudnZ2d(a)posted.grandecom...
>>>>I would like to try this, too.
>>>>
>>>> "Crazy Lary" <email(a)noemail.com> wrote in message
>>>> news:FbidnRR9V_SFPEPUnZ2dnUVZ_hidnZ2d(a)posted.grandecom...
>>>>>I want to toss the power steering. At least to test it. Anyone know
>>>>>where the fuse is located?
>>>>> It's a 2009 Toyota Corolla.
>>>>>
>>>>> thank you,
>>>>>
>>>>> Crazy Larry
>>>>
>>> I doubt if the PS has a fuse, more likely a self-resetting circuit
>>> breaker. If there is a fuse or circuit breaker, it will be in one of the
>>> fuse boxes, more likely the one under the hood. There is probably a
>>> simple way to temporarily disable the electronic power steering, but I
>>> think I'll let owners figure it out themselves rather than give
>>> instructions on how to disable what lawyers, safety advocates,
>>> politicians, people with limited automotive knowledge, and people with
>>> limited driving skills consider a safety feature.
>>> --
>>>
>>> Ray O
>>
>> I am curious about the type of electric power sterring Toyota is using...
>>
>> I had a 2003 Sturn Vue that used an electric motor to supply steering
>> assistance. I thought they all worked like this. However, on Car Talk the
>> other day they were mentioned a system that used an electriclly run
>> hydraulic pump to supply high pressure oil to provide steering asist.
>> This sounded like a system that would use a convention hydralically
>> assisted rack and the only difference was how the hydraulic pressure was
>> supplied. Seemed like a bad idea, but they were talkinig about it...
>>
>
>
> The engine-driven hydraulics are a constant drain on the engine, and
> therefore use more fuel. The electrically driven hydraulics do not drain
> power from the engine, therefore use less fuel.
>
> The electric assist, as I understand it, is a motor -- sort of like a
> starter motor -- that drives the hydraulic assist. The idea is that when
> steering input is sensed, the motor kicks into action to provide the
> hydraulics needed, then shuts off. The electricity to drive the motor puts
> a drain on the engine output, but the drain is transitory instead of
> constant, so the end effect is that less power from the engine is used to
> provide electric power for the steering than the conventional method of
> powering the steering.
>
> If the car is moving at speed and a simple lane change is called out by
> the driver, then the power assist would not be activated, therefore no
> effort from the engine would be expended as it is in the old system of
> pumping the fluid by way of belts on the crankshaft. An added benefit
> could be that the space needed for the belt-driven pump could be used in
> other ways and the electricly driven pump could be put into an otherwise
> unused space.
>
> I don't recall, exactly, but I think the complaints on the electric
> steering is that there is a lag period between the steering input and the
> application of hydraulic pressure to assist the steering. If this is true,
> then the only thing that can be accomplished by removing the fuse for the
> electric motor is to dramatically increase the lag time. If lag time is
> the problem that people have, then what might happen is, the driver
> muscles the car into a right-hand turn and suddenly the power assist kicks
> in and changes the level of effort needed, and this makes the car turn
> more sharply than one might otherwise wish it to turn. Have you ever put
> effort into moving a stuck object, and suddenly the object was freed and
> moved more than you wanted it to? This is a complaint of electric assisted
> steering.
>
>

I think that the electronic PS system does not use hydraulic assist and uses
a motor or servo to move the rack.

The complaints I've heard on Corollas is that the PS system is overly
sensitive, making it difficult for some drivers to maintain straight line at
highway speeds.
--

Ray O
(correct punctuation to reply)


From: Jeff Strickland on 11 Feb 2010 13:07

"Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote in message
news:hl1f39$sj3$1(a)news.eternal-september.org...
>
> "C. E. White" <cewhite3(a)mindspring.com> wrote in message
> news:hl19j0$a23$1(a)news.eternal-september.org...
>>
>> "Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote in message
>> news:hl0652$kug$1(a)news.eternal-september.org...
>>>
>>> "Austin Toyota Club" <Austin Texas> wrote in message
>>> news:Z62dnRpLHd0u6-7WnZ2dnUVZ_vudnZ2d(a)posted.grandecom...
>>>>I would like to try this, too.
>>>>
>>>> "Crazy Lary" <email(a)noemail.com> wrote in message
>>>> news:FbidnRR9V_SFPEPUnZ2dnUVZ_hidnZ2d(a)posted.grandecom...
>>>>>I want to toss the power steering. At least to test it. Anyone know
>>>>>where the fuse is located?
>>>>> It's a 2009 Toyota Corolla.
>>>>>
>>>>> thank you,
>>>>>
>>>>> Crazy Larry
>>>>
>>> I doubt if the PS has a fuse, more likely a self-resetting circuit
>>> breaker. If there is a fuse or circuit breaker, it will be in one of the
>>> fuse boxes, more likely the one under the hood. There is probably a
>>> simple way to temporarily disable the electronic power steering, but I
>>> think I'll let owners figure it out themselves rather than give
>>> instructions on how to disable what lawyers, safety advocates,
>>> politicians, people with limited automotive knowledge, and people with
>>> limited driving skills consider a safety feature.
>>> --
>>>
>>> Ray O
>>
>> I am curious about the type of electric power sterring Toyota is using...
>>
>> I had a 2003 Sturn Vue that used an electric motor to supply steering
>> assistance. I thought they all worked like this. However, on Car Talk the
>> other day they were mentioned a system that used an electriclly run
>> hydraulic pump to supply high pressure oil to provide steering asist.
>> This sounded like a system that would use a convention hydralically
>> assisted rack and the only difference was how the hydraulic pressure was
>> supplied. Seemed like a bad idea, but they were talkinig about it...
>>
>> Ed
>>
> I'm not sure how the electric power steering works, but I am pretty sure
> that it does not use a pump. My understanding is that the electronic PS
> uses some kind of motor or servo, probably similar to what your Vue had.
>
> The EPS is used on Toyota's hybrid vehicles because with an engine-driven
> pump, assist would be lost when the motor shuts down. The disadvantage to
> using an electrically driven pump is that it would need to run whenever
> the vehicle is being driven, which would quickly drain the traction
> battery, or it would need some kind of accumulator tank, which would add
> complexity.
>
> A motor or servo-driven assist would be lighter than a hydraulic system
> and theoretically easier.
>
> --
>

Based on what Ray said, I did a little checking, and found that while I made
some safe assumptions on a motor-driven hydraulic system, the actual system
is more like what Ray said. Check it for yourself,
http://en.wikipedia.org/wiki/Power_steering.

In an internal combustion engine -- as in most cars and trucks -- having an
electric motor drive the hydraulic pump is feasible and would easily do the
job, as Ray points out it would not be a good system for a hybrid car or
truck.

Having said that, the complaints are pretty much in line with those I
described in my earlier post -- the steering response to driver input isn't
very good. As the link points out, steering response in early
implementations of hydraulically assisted steering was not very good either.
The complaints then and now seem to be pretty much the same, give or take a
fine-point here or there.






From: Jeff Strickland on 11 Feb 2010 13:13

"Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote in message
news:hl1gmb$c4e$1(a)news.eternal-september.org...
>>
>
> I think that the electronic PS system does not use hydraulic assist and
> uses a motor or servo to move the rack.
>
> The complaints I've heard on Corollas is that the PS system is overly
> sensitive, making it difficult for some drivers to maintain straight line
> at highway speeds.
> --
>

You're right, there isn't a motor that drives a pump. While such a system
would work fine, that's not what they seem to be using, for lots of reasons
that don't really matter in the realm of this discussion.

I couldn't remember if the complaints were that the steering was slow to
respond and then responded without regard to what had already been
accomplished -- causing a swerve and corrective steering -- or that the
steering was twitchy at highway speeds. Either one would be a problem for
many drivers, mostly by making them uncomfortable if not dangerous.







From: C. E. White on 11 Feb 2010 13:15

"Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message
news:hl1fv0$56m$1(a)news.eternal-september.org...
>> I am curious about the type of electric power sterring Toyota is
>> using...
>>
>> I had a 2003 Sturn Vue that used an electric motor to supply
>> steering assistance. I thought they all worked like this. However,
>> on Car Talk the other day they were mentioned a system that used an
>> electriclly run hydraulic pump to supply high pressure oil to
>> provide steering asist. This sounded like a system that would use a
>> convention hydralically assisted rack and the only difference was
>> how the hydraulic pressure was supplied. Seemed like a bad idea,
>> but they were talkinig about it...
>>
>
>
> The engine-driven hydraulics are a constant drain on the engine, and
> therefore use more fuel. The electrically driven hydraulics do not
> drain power from the engine, therefore use less fuel.

I checked into this further. It seems that you could have a system
with an electric motor driving a hydraulic pump, BUT, this is not the
sort of system used on the car in the Car Talk segment that prompted
my question. It uses a servo motor directly acting in the steering
shaft. In my Vue the motor and controls were all inside the car. They
were attached to the steering column just under the dash. The Vue's
steering had a numb feel, but no worse than many other power assist
systems in other cars I've driven. But then I've never driven anything
as numb as late 60's Chrysler products, so maybe I am biased. I didn't
think the Vue electric power steering was bad, it just wasn't
"sporty."

Interestingly we have another vehicle with electic power steeering - A
Kabota Lawn Tractor.....it works fine.

Ed


> The electric assist, as I understand it, is a motor -- sort of like
> a starter motor -- that drives the hydraulic assist. The idea is
> that when steering input is sensed, the motor kicks into action to
> provide the hydraulics needed, then shuts off. The electricity to
> drive the motor puts a drain on the engine output, but the drain is
> transitory instead of constant, so the end effect is that less power
> from the engine is used to provide electric power for the steering
> than the conventional method of powering the steering.
>
> If the car is moving at speed and a simple lane change is called out
> by the driver, then the power assist would not be activated,
> therefore no effort from the engine would be expended as it is in
> the old system of pumping the fluid by way of belts on the
> crankshaft. An added benefit could be that the space needed for the
> belt-driven pump could be used in other ways and the electricly
> driven pump could be put into an otherwise unused space.
>
> I don't recall, exactly, but I think the complaints on the electric
> steering is that there is a lag period between the steering input
> and the application of hydraulic pressure to assist the steering. If
> this is true, then the only thing that can be accomplished by
> removing the fuse for the electric motor is to dramatically increase
> the lag time. If lag time is the problem that people have, then what
> might happen is, the driver muscles the car into a right-hand turn
> and suddenly the power assist kicks in and changes the level of
> effort needed, and this makes the car turn more sharply than one
> might otherwise wish it to turn. Have you ever put effort into
> moving a stuck object, and suddenly the object was freed and moved
> more than you wanted it to? This is a complaint of electric assisted
> steering.
>
>
>
>
>
>
>


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