Solenoid Actuated Poppet Valves

[BretCahill]

Could a solenoid be constructed to mimic
the proper valve position vs time curve of a
engine cam shaft? Maybe a circuit and/or
several coils in each solenoid?

It may be tricky or impossible to build such
a solenoid that works well over all rpms, but
if it could be built, it could be mass
produced very cheaply, maybe cheaper than
a cam system.

The other concerns such as force necessary to
accelerate valves (are solenoids orders of
magnitude more inefficient than cams?) and
mangled valves from electronic failure (like other
fail safe systems set the default of every valve
in a safe position) shouldn't be problems.


Bret Cahill

 

[Rich Grise]

BretCahill wrote:

Could a solenoid be constructed to mimic
the proper valve position vs time curve of a
engine cam shaft? Maybe a circuit and/or
several coils in each solenoid?

It may be tricky or impossible to build such
a solenoid that works well over all rpms, but
if it could be built, it could be mass
produced very cheaply, maybe cheaper than
a cam system.

The other concerns such as force necessary to
accelerate valves (are solenoids orders of
magnitude more inefficient than cams?) and
mangled valves from electronic failure (like other
fail safe systems set the default of every valve
in a safe position) shouldn't be problems.

I brought this up some time ago in some mechanical group,

and they seemed to indicate that it's been tried a long
long time ago, and abandoned because it's noisy or
something. Actually, I still think it's a pretty cool
idea, when you consider how many HP a camshaft/rocker/
pushrod/lifter arrangement must consume.

And 100-amp semiconductors are common these days.

Anybody want to start hacking their cylinder head? ;-)

Cheers!
Rich

 

[John Larkin]

On 22 Aug 2004 17:25:01 GMT, bretcahill@aol.com (BretCahill) wrote:

Could a solenoid be constructed to mimic
the proper valve position vs time curve of a
engine cam shaft? Maybe a circuit and/or
several coils in each solenoid?

It may be tricky or impossible to build such
a solenoid that works well over all rpms, but
if it could be built, it could be mass
produced very cheaply, maybe cheaper than
a cam system.

The other concerns such as force necessary to
accelerate valves (are solenoids orders of
magnitude more inefficient than cams?) and
mangled valves from electronic failure (like other
fail safe systems set the default of every valve
in a safe position) shouldn't be problems.


Bret Cahill

I'd guess that the forces involved are awfully high for solenoids.
Cooling would be a nasty problem, too. If this worked, the boys in
Detroit or wherever would have done it by now.


Interesting: a cam (especially a roller cam) will return some of the
valve-spring energy to the camshaft when the valve closes, but a
solenoid won't.


John

 

[BretCahill]

John Larkin jjlarkin@highlandSNIPtechTHISnologyPLEASE.com

Message-id: <f2uhi0pie2pgvadslflcqh85sq87uc48m4@4ax.com> writes:

.. . .

Interesting: a cam (especially a roller cam) will return some of the
valve-spring energy to the camshaft when the valve closes, but a
solenoid won't.

I wouldn't be so sure.

A solenoid might be or has been built that
could recapture about as much wasted energy
as that by a cam. As the valve slowed it would
recharge the battery or power the next
cylinder's solenoid.

In any event your concern is valuable, even if
wrong. I didn't think about it and I run energy
balances on everything.


Bret Cahill


"The errors of great men are more fruitful than
the truths of little men."

-- Nietzsche

 

[John Larkin]

On 23 Aug 2004 03:15:07 GMT, bretcahill@aol.com (BretCahill) wrote:

John Larkin jjlarkin@highlandSNIPtechTHISnologyPLEASE.com
Message-id: <f2uhi0pie2pgvadslflcqh85sq87uc48m4@4ax.com> writes:

. . .

Interesting: a cam (especially a roller cam) will return some of the
valve-spring energy to the camshaft when the valve closes, but a
solenoid won't.

I wouldn't be so sure.

A solenoid might be or has been built that
could recapture about as much wasted energy
as that by a cam. As the valve slowed it would
recharge the battery or power the next
cylinder's solenoid.

In any event your concern is valuable, even if
wrong.

Ooh, snotty!

Fast, powerful solenoids have a lot of copper loss, hence the cooling
problem. Not a lot of energy would be recovered.

I'd think that a roller cam could recover at least 60% of the energy
dumped into the valve spring. The exhaust valve does some real work
against pressure, but that's a different issue.

But it's not worth arguing about, or analyzing, because it doesn't
work.

I didn't think about it and I run energy
balances on everything.

I think about everything. That's more fun.

John

 

[Bob Masta]

On 22 Aug 2004 17:25:01 GMT, bretcahill@aol.com (BretCahill) wrote:

Could a solenoid be constructed to mimic
the proper valve position vs time curve of a
engine cam shaft? Maybe a circuit and/or
several coils in each solenoid?

It may be tricky or impossible to build such
a solenoid that works well over all rpms, but
if it could be built, it could be mass
produced very cheaply, maybe cheaper than
a cam system.

The other concerns such as force necessary to
accelerate valves (are solenoids orders of
magnitude more inefficient than cams?) and
mangled valves from electronic failure (like other
fail safe systems set the default of every valve
in a safe position) shouldn't be problems.

I seem to recall reading in mags like EE Times about work
on "electronic valve timing" or words to that effect.
I had the impression that they were using solenoids,
and had similar concerns to yours.

The "all-electronic car" idea seems to be gaining momentum,
but it gives me the creeps, especially when they get to
electronic steering. Seems like they are just trying to make
everything electronic "because they can".

However, many years ago I worked for General Motors
Cadillac Division when electronic fuel injection was just
coming on board. For a while I was one of team that went
around the plant rescuing EFI cars that had died. At the
time it was a really fragile system. There were something like
32 wires to the EFI control box (which was mostly analog!), and
almost any of those could disrupt operation if it came out of
it's little connector. (We carried a supply of paper clips to poke
them back into their shells.) Worse yet, the early EFI system put
a massive amount of fuel into the chambers if you pumped the
pedal when cold-starting, as the drivers were used to doing on
carbureted cars. This would foul the plugs so badly that they
had to be replaced in order to start the car. (Simple manual
cleaning of plugs didn't help.)

I recall thinking that this was a terrible step backward for
overall reliability. There were tons of things that could
completely disable an EFI car, whereas almost nothing
bothered a carburetor short of somebody dismantling it an
throwing in a handful of dirt.

Nowadays, though, EFI is the norm and they certainly seem
to have gotten their act straight. Overall, seems far more
reliable than carburetors. So, maybe someday we'll feel that
way about electronic valve trains and steering. OK, so maybe
a few catastrophic failures in the learning curve to stimulate
new ideas.... <g>


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com

 

[BretCahill]

John Larkin jjlarkin@highlandSNIPtechTHISnologyPLEASE.com in

Message-id: <jotii0to28debeg7rogmmgo87e9hfcffp7@4ax.com> writes:

On 23 Aug 2004 03:15:07 GMT, bretcahill@aol.com (BretCahill) wrote:

John Larkin jjlarkin@highlandSNIPtechTHISnologyPLEASE.com
Message-id: <f2uhi0pie2pgvadslflcqh85sq87uc48m4@4ax.com> writes:

. . .

Interesting: a cam (especially a roller cam) will return some of the
valve-spring energy to the camshaft when the valve closes, but a
solenoid won't.

I wouldn't be so sure.

A solenoid might be or has been built that
could recapture about as much wasted energy
as that by a cam. As the valve slowed it would
recharge the battery or power the next
cylinder's solenoid.

In any event your concern is valuable, even if
wrong.

Ooh, snotty!

I never actually said you were wrong, just that
even if you were wrong, the issue was valuable.

Fast, powerful solenoids have a lot of copper loss, hence the cooling
problem. Not a lot of energy would be recovered.

It's interesting electric motors can be 95%
efficient but something linear is only 0.1%
efficient.

I'd think that a roller cam could recover at least 60% of the energy
dumped into the valve spring.

Sounds reasonable.

The exhaust valve does some real work
against pressure, but that's a different issue.

But it's not worth arguing about, or analyzing, because it doesn't
work.

There are some web sites with solenoid
engines that supposedly run.

I didn't think about it and I run energy
balances on everything.

I think about everything. That's more fun.

That's what we want to hear. Just don't delete
my Nietzsche quote next time.


Bret Cahill

 

[John Larkin]

On 23 Aug 2004 13:04:00 GMT, bretcahill@aol.com (BretCahill) wrote:

John Larkin jjlarkin@highlandSNIPtechTHISnologyPLEASE.com in
Message-id: <jotii0to28debeg7rogmmgo87e9hfcffp7@4ax.com> writes:

On 23 Aug 2004 03:15:07 GMT, bretcahill@aol.com (BretCahill) wrote:

John Larkin jjlarkin@highlandSNIPtechTHISnologyPLEASE.com
Message-id: <f2uhi0pie2pgvadslflcqh85sq87uc48m4@4ax.com> writes:

. . .

Interesting: a cam (especially a roller cam) will return some of the
valve-spring energy to the camshaft when the valve closes, but a
solenoid won't.

I wouldn't be so sure.

A solenoid might be or has been built that
could recapture about as much wasted energy
as that by a cam. As the valve slowed it would
recharge the battery or power the next
cylinder's solenoid.

In any event your concern is valuable, even if
wrong.

Ooh, snotty!

I never actually said you were wrong, just that
even if you were wrong, the issue was valuable.

Fast, powerful solenoids have a lot of copper loss, hence the cooling
problem. Not a lot of energy would be recovered.

It's interesting electric motors can be 95%
efficient but something linear is only 0.1%
efficient.

That is interesting. One difference is that motors have magnets (or
fields) but solenoids generally don't. A linear voice-coil actuator is
sort of half-and-half, and can be reasonably efficient as a
mechanical-to-electrical converter. A solenoid only stores energy in
its inductance (which admittedly decreases in the dropout direction,
which pumps some energy back into the winding) but a millisecond
high-power solenoid will have to have very low inductance and run at
very high peak current, so will be very lossy. A solenoid is just a
linear variable-reluctance motor!

I'd think that a roller cam could recover at least 60% of the energy
dumped into the valve spring.

Sounds reasonable.

The exhaust valve does some real work
against pressure, but that's a different issue.

But it's not worth arguing about, or analyzing, because it doesn't
work.

There are some web sites with solenoid
engines that supposedly run.

Oh, it can be made to work, like variable valve timing and all sorts
of other tricks. But it sounds outrageous to me to replace a nice
reliable cam and a belt with two solenoids and a heap of electronics
per cylinder. I think the 42-volt boys sometimes advocate electrical
valve actuators (and power steering, and air conditioning.) When it
becomes commercially successful and commonly done, I will be suitably
humbled.

I guess you could do the Cadillac variable-number-of-cylinders trick.
You'd have to when a solenoid or a driver fails.

That's what we want to hear. Just don't delete
my Nietzsche quote next time.

You can't restrict my Freedom of Snip rights.

John

 

[Eric R Snow]

On Mon, 23 Aug 2004 13:03:09 GMT, NoSpam@daqarta.com (Bob Masta)
wrote:

On 22 Aug 2004 17:25:01 GMT, bretcahill@aol.com (BretCahill) wrote:

Could a solenoid be constructed to mimic
the proper valve position vs time curve of a
engine cam shaft? Maybe a circuit and/or
several coils in each solenoid?

It may be tricky or impossible to build such
a solenoid that works well over all rpms, but
if it could be built, it could be mass
produced very cheaply, maybe cheaper than
a cam system.

The other concerns such as force necessary to
accelerate valves (are solenoids orders of
magnitude more inefficient than cams?) and
mangled valves from electronic failure (like other
fail safe systems set the default of every valve
in a safe position) shouldn't be problems.


I seem to recall reading in mags like EE Times about work
on "electronic valve timing" or words to that effect.
I had the impression that they were using solenoids,
and had similar concerns to yours.

The "all-electronic car" idea seems to be gaining momentum,
but it gives me the creeps, especially when they get to
electronic steering. Seems like they are just trying to make
everything electronic "because they can".

However, many years ago I worked for General Motors
Cadillac Division when electronic fuel injection was just
coming on board. For a while I was one of team that went
around the plant rescuing EFI cars that had died. At the
time it was a really fragile system. There were something like
32 wires to the EFI control box (which was mostly analog!), and
almost any of those could disrupt operation if it came out of
it's little connector. (We carried a supply of paper clips to poke
them back into their shells.) Worse yet, the early EFI system put
a massive amount of fuel into the chambers if you pumped the
pedal when cold-starting, as the drivers were used to doing on
carbureted cars. This would foul the plugs so badly that they
had to be replaced in order to start the car. (Simple manual
cleaning of plugs didn't help.)

I recall thinking that this was a terrible step backward for
overall reliability. There were tons of things that could
completely disable an EFI car, whereas almost nothing
bothered a carburetor short of somebody dismantling it an
throwing in a handful of dirt.

Nowadays, though, EFI is the norm and they certainly seem
to have gotten their act straight. Overall, seems far more
reliable than carburetors. So, maybe someday we'll feel that
way about electronic valve trains and steering. OK, so maybe
a few catastrophic failures in the learning curve to stimulate
new ideas.... <g


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Greetings Bob,

I used to shudder at the thought of "drive by wire" systems.
Mechanical systems just seemed so robust and forgiving when they do
fail, because often the failure isn't complete, but happens over time.
But, I had the left front suspension break and fold under a car I was
driving. In a parking lot going about 10 mph. There was no controlling
the car. Another time, I heard a squeak coming from the engine
compartment of an econline van I was driving. I turned on the turn
signal to change lanes over to the emergency lane. Before I got there
the shaft going throught the water pump let go and the fan screwed
itself through the radiator. These were sudden failures with no
warning ar just a second or two warning. But many electronic systems
are much less likely to fail. And they really don't wear out. My Dad's
company makes machines which check the probe cards which check the
finished wafers before they are sliced up into seperate dies. He's
been an electronic engineer for about 50 years. When I told him I had
a chip fail in a 20 year old machine he said that the chip was damaged
when new. He said it most likely was not damaged by age or run time.
And that the type of chip it is should function virtually forever. So
I'm waiting for the all electronic car.
ERS

 

[BretCahill]

A lot of people seem worried about a computer
glitch causing the valves to get mangled, etc.
but the drivability of a motor vehicle drops to
zero anyway without the computer. For the
past 20 years automotive computer failure
hasn't been that big problem.

Besides there are various fail safe protections
that could be implemented.


Bret Cahill


Eric R Snow etpm@whidbey.com in

Message-id: <l47ki0lpbsbc3eed0i0st23qanrihdr7d3@4ax.com> writes:

On Mon, 23 Aug 2004 13:03:09 GMT, NoSpam@daqarta.com (Bob Masta)
wrote:

On 22 Aug 2004 17:25:01 GMT, bretcahill@aol.com (BretCahill) wrote:

Could a solenoid be constructed to mimic
the proper valve position vs time curve of a
engine cam shaft? Maybe a circuit and/or
several coils in each solenoid?

It may be tricky or impossible to build such
a solenoid that works well over all rpms, but
if it could be built, it could be mass
produced very cheaply, maybe cheaper than
a cam system.

The other concerns such as force necessary to
accelerate valves (are solenoids orders of
magnitude more inefficient than cams?) and
mangled valves from electronic failure (like other
fail safe systems set the default of every valve
in a safe position) shouldn't be problems.


I seem to recall reading in mags like EE Times about work
on "electronic valve timing" or words to that effect.
I had the impression that they were using solenoids,
and had similar concerns to yours.

The "all-electronic car" idea seems to be gaining momentum,
but it gives me the creeps, especially when they get to
electronic steering. Seems like they are just trying to make
everything electronic "because they can".

However, many years ago I worked for General Motors
Cadillac Division when electronic fuel injection was just
coming on board. For a while I was one of team that went
around the plant rescuing EFI cars that had died. At the
time it was a really fragile system. There were something like
32 wires to the EFI control box (which was mostly analog!), and
almost any of those could disrupt operation if it came out of
it's little connector. (We carried a supply of paper clips to poke
them back into their shells.) Worse yet, the early EFI system put
a massive amount of fuel into the chambers if you pumped the
pedal when cold-starting, as the drivers were used to doing on
carbureted cars. This would foul the plugs so badly that they
had to be replaced in order to start the car. (Simple manual
cleaning of plugs didn't help.)

I recall thinking that this was a terrible step backward for
overall reliability. There were tons of things that could
completely disable an EFI car, whereas almost nothing
bothered a carburetor short of somebody dismantling it an
throwing in a handful of dirt.

Nowadays, though, EFI is the norm and they certainly seem
to have gotten their act straight. Overall, seems far more
reliable than carburetors. So, maybe someday we'll feel that
way about electronic valve trains and steering. OK, so maybe
a few catastrophic failures in the learning curve to stimulate
new ideas.... <g


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Greetings Bob,
I used to shudder at the thought of "drive by wire" systems.
Mechanical systems just seemed so robust and forgiving when they do
fail, because often the failure isn't complete, but happens over time.
But, I had the left front suspension break and fold under a car I was
driving. In a parking lot going about 10 mph. There was no controlling
the car. Another time, I heard a squeak coming from the engine
compartment of an econline van I was driving. I turned on the turn
signal to change lanes over to the emergency lane. Before I got there
the shaft going throught the water pump let go and the fan screwed
itself through the radiator. These were sudden failures with no
warning ar just a second or two warning. But many electronic systems
are much less likely to fail. And they really don't wear out. My Dad's
company makes machines which check the probe cards which check the
finished wafers before they are sliced up into seperate dies. He's
been an electronic engineer for about 50 years. When I told him I had
a chip fail in a 20 year old machine he said that the chip was damaged
when new. He said it most likely was not damaged by age or run time.
And that the type of chip it is should function virtually forever. So
I'm waiting for the all electronic car.
ERS

 

[BretCahill]

NoSpam@daqarta.com (Bob Masta) in

Message-id: <4129e6f4.2009230@news.itd.umich.edu> writes:

On 22 Aug 2004 17:25:01 GMT, bretcahill@aol.com (BretCahill) wrote:

Could a solenoid be constructed to mimic
the proper valve position vs time curve of a
engine cam shaft? Maybe a circuit and/or
several coils in each solenoid?

It may be tricky or impossible to build such
a solenoid that works well over all rpms, but
if it could be built, it could be mass
produced very cheaply, maybe cheaper than
a cam system.

The other concerns such as force necessary to
accelerate valves (are solenoids orders of
magnitude more inefficient than cams?) and
mangled valves from electronic failure (like other
fail safe systems set the default of every valve
in a safe position) shouldn't be problems.

I seem to recall reading in mags like EE Times about work
on "electronic valve timing" or words to that effect.
I had the impression that they were using solenoids,
and had similar concerns to yours.

The "all-electronic car" idea seems to be gaining momentum,
but it gives me the creeps, especially when they get to
electronic steering. Seems like they are just trying to make
everything electronic "because they can".

I hate the way every microwave oven is
different. Just put a dial on the #@!&%! thing
and forget being cute with a lot of buttons.

However, many years ago I worked for General Motors
Cadillac Division when electronic fuel injection was just
coming on board. For a while I was one of team that went
around the plant rescuing EFI cars that had died. At the
time it was a really fragile system. There were something like
32 wires to the EFI control box (which was mostly analog!), and
almost any of those could disrupt operation if it came out of
it's little connector. (We carried a supply of paper clips to poke
them back into their shells.) Worse yet, the early EFI system put
a massive amount of fuel into the chambers if you pumped the
pedal when cold-starting, as the drivers were used to doing on
carbureted cars. This would foul the plugs so badly that they
had to be replaced in order to start the car. (Simple manual
cleaning of plugs didn't help.)

Good story.

I recall thinking that this was a terrible step backward for
overall reliability. There were tons of things that could
completely disable an EFI car, whereas almost nothing
bothered a carburetor short of somebody dismantling it an
throwing in a handful of dirt.

Nowadays, though, EFI is the norm and they certainly seem
to have gotten their act straight. Overall, seems far more
reliable than carburetors.

Maybe someone knew what he was doing.

So, maybe someday we'll feel that
way about electronic valve trains and steering. OK, so maybe
a few catastrophic failures in the learning curve to stimulate
new ideas.... <g

In politics we're talking trillions of dollars down
the drain.

An unreliable piece of electrical or mechanical
junk is positively charming in comparison.

Where do I sign up?

Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com

 

[BretCahill]

John Larkin jjlarkin@highlandSNIPtechTHISnologyPLEASE.com in

Message-id: <vk3ki0hucb91bpjmke3nlcp08l423kbka5@4ax.com> writes:

On 23 Aug 2004 13:04:00 GMT, bretcahill@aol.com (BretCahill) wrote:

John Larkin jjlarkin@highlandSNIPtechTHISnologyPLEASE.com in
Message-id: <jotii0to28debeg7rogmmgo87e9hfcffp7@4ax.com> writes:

On 23 Aug 2004 03:15:07 GMT, bretcahill@aol.com (BretCahill) wrote:

John Larkin jjlarkin@highlandSNIPtechTHISnologyPLEASE.com
Message-id: <f2uhi0pie2pgvadslflcqh85sq87uc48m4@4ax.com> writes:

. . .

Interesting: a cam (especially a roller cam) will return some of the
valve-spring energy to the camshaft when the valve closes, but a
solenoid won't.

I wouldn't be so sure.

A solenoid might be or has been built that
could recapture about as much wasted energy
as that by a cam. As the valve slowed it would
recharge the battery or power the next
cylinder's solenoid.

In any event your concern is valuable, even if
wrong.

Ooh, snotty!

I never actually said you were wrong, just that
even if you were wrong, the issue was valuable.

Fast, powerful solenoids have a lot of copper loss, hence the cooling
problem. Not a lot of energy would be recovered.

It's interesting electric motors can be 95%
efficient but something linear is only 0.1%
efficient.


That is interesting. One difference is that motors have magnets (or
fields) but solenoids generally don't. A linear voice-coil actuator is
sort of half-and-half, and can be reasonably efficient as a
mechanical-to-electrical converter. A solenoid only stores energy in
its inductance (which admittedly decreases in the dropout direction,
which pumps some energy back into the winding) but a millisecond
high-power solenoid will have to have very low inductance and run at
very high peak current, so will be very lossy. A solenoid is just a
linear variable-reluctance motor!

I'd think that a roller cam could recover at least 60% of the energy
dumped into the valve spring.

Sounds reasonable.

The exhaust valve does some real work
against pressure, but that's a different issue.

But it's not worth arguing about, or analyzing, because it doesn't
work.

There are some web sites with solenoid
engines that supposedly run.


Oh, it can be made to work, like variable valve timing and all sorts
of other tricks. But it sounds outrageous to me to replace a nice
reliable cam and a belt with two solenoids and a heap of electronics
per cylinder. I think the 42-volt boys sometimes advocate electrical
valve actuators (and power steering, and air conditioning.) When it
becomes commercially successful and commonly done, I will be suitably
humbled.

I guess you could do the Cadillac variable-number-of-cylinders trick.

That's what started it. Instead of one engine,
I'ld have 2. A low power high efficiency engine
for 50 mpg and a high power low efficiency
engine in case you needed to haul something
or get on the freeway fast.

Someone mentioned a convertable 4 stroke/
2stroke engine and either you had to slide the
cam shaft off the rocker arms or you had to
operate the valves some other way.


Bret Cahill

 

[John Larkin]

On 24 Aug 2004 04:20:38 GMT, bretcahill@aol.com (BretCahill) wrote:

I guess you could do the Cadillac variable-number-of-cylinders trick.

That's what started it. Instead of one engine,
I'ld have 2. A low power high efficiency engine
for 50 mpg and a high power low efficiency
engine in case you needed to haul something
or get on the freeway fast.

Someone mentioned a convertable 4 stroke/
2stroke engine and either you had to slide the
cam shaft off the rocker arms or you had to
operate the valves some other way.

Actually, existing engines are awfully good. Their only problem is
that most of them are designed to accelerate 5000 pounds of ugly steel
surrounding one 110-pound soccer mom. We don't really need more
efficient engines as much as we need higher gas prices. No major
technological breakthroughs are needed to make that happen.

John

 

[colin]

"BretCahill" <bretcahill@aol.com> wrote in message
news:20040822132501.14634.00002073@mb-m29.aol.com...

Could a solenoid be constructed to mimic
the proper valve position vs time curve of a
engine cam shaft? Maybe a circuit and/or
several coils in each solenoid?

It may be tricky or impossible to build such
a solenoid that works well over all rpms, but
if it could be built, it could be mass
produced very cheaply, maybe cheaper than
a cam system.

The other concerns such as force necessary to
accelerate valves (are solenoids orders of
magnitude more inefficient than cams?) and
mangled valves from electronic failure (like other
fail safe systems set the default of every valve
in a safe position) shouldn't be problems.


Bret Cahill

i seem to remember hearing long time ago that the amount of instantaneous
power required for a solenoid to operate normal valves with return springs
is so large that the resulting inefeciencies leads to a very large power
consumption making it rather ineficient. maybe with latest magnets or
posibly even high temperature superconductors it wld be advantagous. maybe a
stepper motor could be used instead, with a similar arangement used inside
disc head actuators.

however there are alternatives, depends what you are trying to acheive,
variable valve timing has been acehived with hydrolics on lotus and now
other cars i think, however why restrict yourslef to popet valves, consider
desmodronic valves wich have no return spring but rely on a 2nd mechanical
or potentialy electromechanical force to return the valve, and the presure
inside the cylnder finshes the job.

alternatvly the cam shaft could simply be driven by a steper motor, or the
cam shaft cld be driven in the normal way but a mechanism driven by a steper
motor could alter the angle of the cam shaft relative to the drive drive
puley.

there was talk about an all ceramic engine being 10 years away but i heard
this wel over 10 years ago i think, i always wondered about the posibility
of sliding valves, maybe just a rotating disc, posibly ceramic just like in
some taps, they are very efiecient in the amount of energy required to
operate them and give good life.

Colin =^.^=

 

[James Newton]

bretcahill@aol.com (BretCahill) wrote in message news:<20040822132501.14634.00002073@mb-m29.aol.com>...

Could a solenoid be constructed to mimic
the proper valve position vs time curve of a
engine cam shaft?

Anything is possible, but if you just want variable valve timing try
this:

Convert the lifters to have little thin rollers on the end... sort of
like tiny inline skate wheels but made from steel and running on a
bearing. Now the lifter is only useing a narrow section of the
circumference of the cam lobe.

Next, make each cam lobe segment very narrow and stack several
different shaped lobes right next to each other.

Finally, shift the cam shaft in and out as it turns.

I personally did a VERY crude version of this years ago on my first
"hot rod" as a teenager. I wanted to grind the cam shaft as several of
the other "gang" had done, but I knew my dad would kill me if he ever
heard the car running rough so I ground HALF of each cam lobe, added a
crude lever system to shift the cam in and out about 1/4 inch which
was all the play I could get out of the cam journals. It was enough,
and I could idle quietly out the drive way, reach under the dash, pull
the lever and be "one of the cool ones."

Of course I totalled the car about 6 months later and my Dad did the
worst possible thing to punish me: He cried. Later though, when he
noticed the "modification" he helped me start a rebuild on the car.
Didn't finish it, but I took it as a sign he had been impressed.

Anyway, I've never seen such a thing since, but I've been out of cars
for a long time.

 

[BretCahill]

Someone suggested a 2-stroke/4-stroke
convertable engine. 4-stroke if gas was
expensive and four stroke if you needed more
power.

The sliding cam was the only way other than
solenoids.


Bret Cahill

 

[Clint Sharp]

In message <545d8ce4.0408241554.21009c10@posting.google.com>, James
Newton <jamesnewton@geocities.com> writes

bretcahill@aol.com (BretCahill) wrote in message
news:<20040822132501.14634.00002073@mb-m29.aol.com>...
Could a solenoid be constructed to mimic
the proper valve position vs time curve of a
engine cam shaft?

Anything is possible, but if you just want variable valve timing try
this:
Snip,

Fiat use a scheme like this. Their system uses two meshing cross cut
gears, one internal and the external one is rotated to push/pull the
camshaft in and out to a different portion of the profile
--
Clint Sharp

 

[BobGardner]

Could a solenoid be constructed to mimic
the proper valve position vs time curve of a
engine cam shaft?
===================

http://rbowes1.11net.com/dbowes/

 

[Stan Blazejewski]

On 29 Aug 2004 21:12:30 GMT, bobgardner@aol.comma (BobGardner) wrote:

Could a solenoid be constructed to mimic
the proper valve position vs time curve of a
engine cam shaft?
===================
http://rbowes1.11net.com/dbowes/

Thats' been done already, they're still ironing out the bugs.... not

ready for domestic use 'yet'.

I must say I just 'love' the possibilities this will introduce.
Imagine an engine that could putt around in city traffic & still go
like a Ferari on the open road.
--

Australia isn't "down under", it's "off to one side"!

stanblaz@netspace.net.au
www.stanblaz.customer.netspace.net.au
www.cobracat.com (home of the Australian Cobra Catamaran)