Camless Engine News **Available in less than five years (page 1)**
10-16-2005 | 09:17 PM
#1
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Camless Engine News **Available in less than five years (page 1)**
Valeo tests camless system for gas engines; supplier hopes to produce fuel-saving technology by '08 - - RICHARD TRUETT | Automotive News - - Source: Autoweek
Valeo SA engineers say they are close to perfecting camless technology for traditional gasoline engines.
A camless gasoline engine would reduce fuel consumption drastically -- 20 percent, according to Valeo -- challenging hybrids and diesels in the race to improve fuel economy.
Tough technical challenges have kept camless technology off the market. Engineers have grappled with a variety of issues, such as precisely opening and closing the valves electronically, packaging the system to fit inside the engine and developing the software to operate the valves. Cost also has been an issue.
Valeo CEO Thierry Morin says his company has two development contracts for the system.
"As far as we are concerned, we are between 14 and 16 months from market. So you see that we are there," Morin said in a recent interview. He said he expects to have the system in production in North America and Europe as early as 2008.
Valeo engineers have built and are testing two Peugeot 407s with the system. Morin says both cars have worked well in different weather extremes and under strenuous testing.
How it works
In all automobile engines, the crankshaft is connected to the camshaft with a belt, chain or gears. As the crankshaft spins, it turns the camshaft, which in turn opens the intake and exhaust valves in sequence. Much of the energy produced by the engine is lost because the crankshaft has to spin the camshaft.
In a camless engine, the valves are opened and closed electronically.
The advantages are numerous:
Internal friction is reduced greatly because there are fewer moving parts. At low speeds, about 25 percent of an engine's friction is caused by the valvetrain.
Horsepower, torque and fuel economy are improved because the crankshaft's power is driving only the wheels.
Emissions are reduced because the computer-controlled valve timing is infinitely variable. Each valve in each cylinder can be opened and closed independently, something not possible with a traditional engine.
Valeo's system uses electromagnetic actuators to open and close the valves. The actuators are placed on top of each valve under the valve cover.
Valeo, of Paris, specializes in transmissions, motors, actuators, switches and electronics. The company would not say who its customers are, but it's likely PSA/Peugeot-Citroen SA would be a customer. Valeo already supplies a mild hybrid for a Citroen model.
Valeo ranks No. 13 on the Automotive News list of top 100 global suppliers with worldwide original-equipment automotive parts sales of $9.9 billion in 2004.
The Holy Grail
Camless engine technology long has been a holy grail of engineers from automakers and suppliers. BMW AG, for instance, has spent millions trying to perfect a camless system. But no one has developed a camless engine system that delivers the reliability of the camshaft for anywhere near the same price.
But Morin says the reliability and cost are no longer the biggest obstacles. "With a camless system there is a strong need for the automaker to change the architecture of its engine. And this is what is time-consuming. It will have to start initially on low-volume engines," Morin says.
Peter Brown, vice president of powertrain engineering and design for Ricardo Inc. of Detroit, says his company also is working on a camless engine system. He says a 20 percent reduction in fuel usage is more than Ricardo engineers would expect a camless system to deliver.
Brown says perfecting a camless engine is one of his company's most important projects. With fuel prices hovering at $3 per gallon, there is a renewed emphasis on developing such a system, he says.
Engine improvements rarely yield more than a few percentage points of fuel economy gains. To get 20 percent with just one system would be a colossal jump.
"It comes to down to complexity and cost," Brown says. "Technically there is enough knowledge. People have experimented with all sorts of techniques."
Brown also warns of the dangers of camless engines. A computer glitch or electrical problem, for instance, might cause a vehicle to fail to meet emissions standards. Or worse, if the valves opened at the wrong time, the pistons might hit them, destroying the engine.
A camless gasoline engine would reduce fuel consumption drastically -- 20 percent, according to Valeo -- challenging hybrids and diesels in the race to improve fuel economy.
Tough technical challenges have kept camless technology off the market. Engineers have grappled with a variety of issues, such as precisely opening and closing the valves electronically, packaging the system to fit inside the engine and developing the software to operate the valves. Cost also has been an issue.
Valeo CEO Thierry Morin says his company has two development contracts for the system.
"As far as we are concerned, we are between 14 and 16 months from market. So you see that we are there," Morin said in a recent interview. He said he expects to have the system in production in North America and Europe as early as 2008.
Valeo engineers have built and are testing two Peugeot 407s with the system. Morin says both cars have worked well in different weather extremes and under strenuous testing.
How it works
In all automobile engines, the crankshaft is connected to the camshaft with a belt, chain or gears. As the crankshaft spins, it turns the camshaft, which in turn opens the intake and exhaust valves in sequence. Much of the energy produced by the engine is lost because the crankshaft has to spin the camshaft.
In a camless engine, the valves are opened and closed electronically.
The advantages are numerous:
Internal friction is reduced greatly because there are fewer moving parts. At low speeds, about 25 percent of an engine's friction is caused by the valvetrain.
Horsepower, torque and fuel economy are improved because the crankshaft's power is driving only the wheels.
Emissions are reduced because the computer-controlled valve timing is infinitely variable. Each valve in each cylinder can be opened and closed independently, something not possible with a traditional engine.
Valeo's system uses electromagnetic actuators to open and close the valves. The actuators are placed on top of each valve under the valve cover.
Valeo, of Paris, specializes in transmissions, motors, actuators, switches and electronics. The company would not say who its customers are, but it's likely PSA/Peugeot-Citroen SA would be a customer. Valeo already supplies a mild hybrid for a Citroen model.
Valeo ranks No. 13 on the Automotive News list of top 100 global suppliers with worldwide original-equipment automotive parts sales of $9.9 billion in 2004.
The Holy Grail
Camless engine technology long has been a holy grail of engineers from automakers and suppliers. BMW AG, for instance, has spent millions trying to perfect a camless system. But no one has developed a camless engine system that delivers the reliability of the camshaft for anywhere near the same price.
But Morin says the reliability and cost are no longer the biggest obstacles. "With a camless system there is a strong need for the automaker to change the architecture of its engine. And this is what is time-consuming. It will have to start initially on low-volume engines," Morin says.
Peter Brown, vice president of powertrain engineering and design for Ricardo Inc. of Detroit, says his company also is working on a camless engine system. He says a 20 percent reduction in fuel usage is more than Ricardo engineers would expect a camless system to deliver.
Brown says perfecting a camless engine is one of his company's most important projects. With fuel prices hovering at $3 per gallon, there is a renewed emphasis on developing such a system, he says.
Engine improvements rarely yield more than a few percentage points of fuel economy gains. To get 20 percent with just one system would be a colossal jump.
"It comes to down to complexity and cost," Brown says. "Technically there is enough knowledge. People have experimented with all sorts of techniques."
Brown also warns of the dangers of camless engines. A computer glitch or electrical problem, for instance, might cause a vehicle to fail to meet emissions standards. Or worse, if the valves opened at the wrong time, the pistons might hit them, destroying the engine.
10-16-2005 | 09:36 PM
#2
Instructor
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From: Toronto_CA
Very interesting. Just when people thought the SOHC/DOHC engines reached its technological limits.
It looks like everything is now being managed by a computer. The days of "Sunday Mechanics" are almost over. The most common troubleshooting step will be to swap the onboard computer. No need for mechanics, just sign everyone for IBM first-line helpdesk.
It looks like everything is now being managed by a computer. The days of "Sunday Mechanics" are almost over. The most common troubleshooting step will be to swap the onboard computer. No need for mechanics, just sign everyone for IBM first-line helpdesk.
10-17-2005 | 01:02 PM
#4
Drifting
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This is the future, my friends. Now imagine a hybrid, cam-less engine - think of the power and fuel economy! Now a freind of mine that is big into F1 racing told me that F1 cars already use this technology (I'm not into F1 so I just assumed he was telling the truth). Figuring because of the cost and complexity, only certain manufacturers will jump at this new technology at first. I can see this coming out in BMW's, then slowly trickling down their line and then to lesser brands with GM being the very, very last manufacturer to offer it probably in the Cadillac line-up.
10-17-2005 | 04:34 PM
#7
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Originally Posted by 65 Fury Convert
This is the future, my friends. Now imagine a hybrid, cam-less engine - think of the power and fuel economy! Now a freind of mine that is big into F1 racing told me that F1 cars already use this technology (I'm not into F1 so I just assumed he was telling the truth). Figuring because of the cost and complexity, only certain manufacturers will jump at this new technology at first. I can see this coming out in BMW's, then slowly trickling down their line and then to lesser brands with GM being the very, very last manufacturer to offer it probably in the Cadillac line-up.
Here is my guess:
I am not sure if BMW will be the first we'll see this out of. Maybe, but for sure Nissan will be either THE first, or one of the first to execute on this. Why? Because of their association with Renault which is also very closely associated with Valeo and a Champiom within F1 currently.
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10-17-2005 | 04:34 PM
#9
Kenpachi Teichou
Joined: May 2004
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From: San Diego, CA
That's pretty cool, but what I really want to see is the quasiturbine engine in production http://auto.howstuffworks.com/quasiturbine.htm
10-17-2005 | 05:00 PM
#10
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From: Alexandria, VA
Fuel injectors are already on just about every car and that is a sort of an actuator whose reliability seems to be pretty good. This would be something like that on a bigger scale with a bit stronger actuator. The thing is the more actuators, the more expensive and complex the system so it might first be tried out on some 4 cyl 2 valve/cyl engine. Going straight to some 32 valve 8 cyl engine might be pushing it. Seems to me that if they already tried it in one, the 407 would probably be most obvious choice to offer it in production.
10-17-2005 | 05:38 PM
#11
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^ I was under the impression that the biggest challenge with these actuators was basically electrical capacity. At 12V, cars are not built to support anything near this kind of power needed by an actuator which will govern a valve at these speeds and power. Of course, the very much anticipated 42V is supposedly on the horizon, but I have not heard anything about it for a while now, plus I am not sure if even that will suffice.
10-18-2005 | 04:00 PM
#12
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From: Alexandria, VA
The 42V standard rollout seems to have been slipping quite a bit. I seem to recall Caddy was going to offer it real soon. Yes, the power draw of the acutator might be an issue but I suspect reliability and control are also problem areas. Plus it's probably not exactly a slap on kind of design - designing a camless engine from the ground up takes a while.
Biker, who kind of doubts the 20% milage gain claim.
Biker, who kind of doubts the 20% milage gain claim.
10-18-2005 | 04:41 PM
#13
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From: Chicago Suburbs
This is a pretty cool technology. It will definetly improve fuel economy and power. A camless engine will have less friction and act like Displacement on demand that we are seeing in current cars. I believe the 20% increase in fuel economy, but only on the highway. If this technology becomes affordable and direct injection becomes more widespread in gasoline engine, this will give internal combustion engines a longer lifespan. Think about it; near hybrid level emissions, a 20-30% increase in fuel economy, and more power. Sounds like a winner to me.
12-21-2006 | 06:34 PM
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Valeo signs up 'several global automakers' for camless engine - - By JENS MEINERS | JESSE SNYDER | AUTOMOTIVE NEWS - - Source: Autoweek
MORTEFONTAINE, France -- Valeo SA has several development contracts with automakers for its camless engine, industry sources say.
The technology is expected to be available in less than five years.
"We will have an engine on the market by 2010 or 2011," says Martin Haub, Valeo board member for r&d. "Development is under way."
A Valeo spokesman would not confirm the contracts but said the French supplier is "working with several global automakers" on camless engines. He declined to identify any of them.
At the proving grounds here near Paris, where journalists could drive a car with a prototype camless engine, Haub told Automotive News Europe that Valeo's project is half-camless - only the intake valves are electronically actuated. That gives 80 percent of the performance of a fully camless engine, which Valeo also is working on, at half the cost, he said.
Industry sources said the manufacturing cost of a four-cylinder, half-camless gasoline engine is about 300 euros (about $395 at current exchange rates) more than a conventional gasoline engine. When asked to confirm that price, Haub said Valeo's solution is substantially less than the price premium for a modern diesel engine.
Engine developers have long been interested in camless technology's promise of as much as 20 percent better fuel economy over a conventional engine.
Also, there is less complexity and less weight because mechanical camshafts and related parts are eliminated.
BMW is following developments in the technology but is concerned about cost and durability, says Christian Bock, the automaker's V-8 engine calibration general manager.
"The technical barrier is not the valve actuators but the sensors to make the thing work," he said. "The sensors (still) are not accurate enough and have engine-life durability and reliability issues."
But Bock said one appealing point is that camless engines do not depend on fuel quality like diesel or gasoline direct-injection engines do. "It's a global solution, and the other two are only regional for now," he said.
Haub said Valeo's half-camless engine would improve fuel consumption 15 to 20 percent and provide 15 to 20 percent more low-end torque than a conventional gasoline engine.
The technology is expected to be available in less than five years.
"We will have an engine on the market by 2010 or 2011," says Martin Haub, Valeo board member for r&d. "Development is under way."
A Valeo spokesman would not confirm the contracts but said the French supplier is "working with several global automakers" on camless engines. He declined to identify any of them.
At the proving grounds here near Paris, where journalists could drive a car with a prototype camless engine, Haub told Automotive News Europe that Valeo's project is half-camless - only the intake valves are electronically actuated. That gives 80 percent of the performance of a fully camless engine, which Valeo also is working on, at half the cost, he said.
Industry sources said the manufacturing cost of a four-cylinder, half-camless gasoline engine is about 300 euros (about $395 at current exchange rates) more than a conventional gasoline engine. When asked to confirm that price, Haub said Valeo's solution is substantially less than the price premium for a modern diesel engine.
Engine developers have long been interested in camless technology's promise of as much as 20 percent better fuel economy over a conventional engine.
Also, there is less complexity and less weight because mechanical camshafts and related parts are eliminated.
BMW is following developments in the technology but is concerned about cost and durability, says Christian Bock, the automaker's V-8 engine calibration general manager.
"The technical barrier is not the valve actuators but the sensors to make the thing work," he said. "The sensors (still) are not accurate enough and have engine-life durability and reliability issues."
But Bock said one appealing point is that camless engines do not depend on fuel quality like diesel or gasoline direct-injection engines do. "It's a global solution, and the other two are only regional for now," he said.
Haub said Valeo's half-camless engine would improve fuel consumption 15 to 20 percent and provide 15 to 20 percent more low-end torque than a conventional gasoline engine.
12-21-2006 | 06:39 PM
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20% more torque is substantial IMO.
I dont understand why the comparison between diesel and camless with respect to gas consumption, cost, comlexity, etc? What I see here is yet another technology to be ADDED to the mix in order to come closer to a more efficient engine.
I dont understand why the comparison between diesel and camless with respect to gas consumption, cost, comlexity, etc? What I see here is yet another technology to be ADDED to the mix in order to come closer to a more efficient engine.
12-21-2006 | 06:43 PM
#16
Fahrvergnügen'd
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This is amazing technology but it just moves owners one more step further from being able to fix their own cars. Not to mention it makes getting SAE mechanics more expensive because they have to have CS degrees 
12-22-2006 | 08:16 AM
#18
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Last edited by Black Tire; 12-22-2006 at 08:18 AM.
12-22-2006 | 09:34 AM
#19
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Like many other things you don't want to own V 1.0 of this technology, although it sounds very promising.
The diesel premium is probably around $1K - MB charges about that for the E320 Blutec over the E350. If this gives the same tq/gas milage boost as diesel with the needed reliability it might be time to look at Valeo stock.
The diesel premium is probably around $1K - MB charges about that for the E320 Blutec over the E350. If this gives the same tq/gas milage boost as diesel with the needed reliability it might be time to look at Valeo stock.
12-22-2006 | 10:57 AM
#20
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Originally Posted by charliemike
This is amazing technology but it just moves owners one more step further from being able to fix their own cars. Not to mention it makes getting SAE mechanics more expensive because they have to have CS degrees
The people with the CS degrees make software that "everyday" people can use.
12-22-2006 | 02:34 PM
#21
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Originally Posted by Black Tire
I am under the impression that all F1 engines are camless for several years now. Pneumatic valves, I believe is the term.
12-22-2006 | 05:51 PM
#22
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From: philly
Originally Posted by stangg172004
i hope the germans dont get into this, imagine the electrical problems their cars will have 15 years from whenever they start making them 
I'll take electrical problems from the germans, which can be worked out, versus other auto companies avoiding new technology altogether.
12-23-2006 | 03:22 AM
#23
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Originally Posted by gavriil
I am under the impression that all F1 engines are camless for several years now. Pneumatic valves, I believe is the term.
I believe current F1 engines still use camshafts to open up the valves. The problems lies with shutting the valves fast enough at high rpm so the pistons don't collide with them on way up.
It's simple physics really, a spring doesn't have enough force to accelerate the valves at extremely high rpms (above 14 or 15k rpm I believe) due to newtons second law (Force = mass * acceleration). At high rpm the accelerations needed for the valve to close are huge and that requires massive forces that a spring cannot produce. The force a spring exerts does not increase at high engine rpm, it depends only on the amount of compression in the spring which does not vary with rpm (even with multiple cam profiles like in VTEC).
The solution to this is to remove the valve springs all together and use compressed air to shut the valves because it can produce much larger forces. And yes, the correct term for it is pneumatic valves.
03-04-2007 | 06:07 PM
#24
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Camless engines
Here are some of my views on valve control techniques - your comments welcome
VALVE SPRINGS
Valve springs are the primary limiting factor on engine speeds, and generate many unpleasant effects, such as harmonics and valve float. Without them there is relatively little friction in the valve train.
The push to create a camless engine misses the point. The springs are the problem, not the cam shafts.
Most of the systems described below still utilize springs with all their incumbent problems.
ELECTRO MECHANICAL
This method of valve control is often found in camless engine designs. A proponent of this technology is Valeo, which indicates that its design will be utilized in volume production in 2009.
http://www.valeo.com/automotive-supplier/Jahia/pid/1317
Some of the problems which may be encountered with this methodology are:
- Deceleration of the valve once set in motion is difficult to accomplish, and inadequate slowing down of the valve can cause significant deterioration of the valve seat and other parts. Utilizing springs to effect valve deceleration limits the engine to lower speeds and may still not effect a gentle landing of the valve on its seat at all engine speeds.
- Springs utilized in this type of system may require very careful balancing with the valve movement in order to achieve gentle valve seating at differing engine speeds. As the springs deteriorate, the valve mechanism may become unbalanced and ultimately lead to failure.
- The electromagnets will draw a significant amount of electrical energy, which may require a higher capacity alternator, which will in turn reduce the potential fuel efficiency of the engine.
- A powerful computer coupled with complex fast-acting control circuitry and devices will likely be necessary to control the valves in real time.
HYDRAULIC
This type of valve control has been advocated in the search for a camless engine. Sturman Industries, which incorporated its design into a large truck engine a number of years ago, is a proponent of this technology.
http://www.sturmanindustries.com/mai...eActuation.htm
Various methods have been explored to utilize hydraulic mechanisms to move the engine valves. Some claim to be successful at low engine speeds, but few claim to achieve that goal meaningfully at the higher RPM requirements of passenger vehicles..
Hydraulic systems suffer from 2 inherent problems :
1) The faster a liquid is moved, the more it tends to act like a solid. A fast-acting hydraulic system to activate automotive valves at the speeds required in passenger vehicles could require immense pressures, with all the incumbent problems, including the additional energy requirements of the hydraulic pump. Even if higher engine speeds were achieved, valve movement would likely be abbreviated and not fully follow the desired or optimum lift schedule.
2) Temperatures can vary seasonally over a wide range. The hydraulic medium could change viscosity as the temperatures change, which could cause variances in the system’s performance which may be difficult to control.
Utilizing valve springs to assist the hydraulic system may also prevent the engine attaining higher speeds.
In order to achieve gentle valve seating, hydraulic systems must be carefully controlled. This control may require the use of powerful computers and very precise sensors.
DESMODROMIC
This form of valve control utilizes camshafts but not conventional valve springs. A long-time proponent of this technology is Ducati, which has successfully used this methodology in their motorcycles.
http://www.ducati.com/
This methodology removes the valve spring limitation on engine RPMs. However, other factors such as the use of rocker arms to open and close the valves may have a limiting effect on performance.
A desmodromic system does not normally provide for positive seating of the valves, as they are for the most part held closed by gas pressures in the cylinder. The exception could be the exhaust valve, which may be partially open in the “closed” position during the intake stroke.
There are no known variable duration systems utilizing this methodology.
PNEUMATIC
Systems utilizing pneumatics to drive the engine valves would in all probability not be feasible because of their complexity and the very large amount of energy required to compress the air.
VARIANTS ON CURRENT CAM TECHNOLOGY
There are a number of mechanical valve operating systems based on traditional cam technology. Many rely on an offset gear to slow the cam as it opens the valve, thereby prolonging the valve-opening duration. This together with cam phasing provides a limited form of variable duration. An example of this technology is the K series engine produced by Rover.
http://www.sandsmuseum.com/cars/elis...ngine/vvc2.pdf
Problems with this methodology generally stem from the complexity and size of the units, the slow opening and closing of the valves, and the limited available variation in valve opening and closing times. Additionally, the valves may have to be lifted higher than their theoretical optimum height in order to achieve optimum gas flow.
Some examples of this methodology only provide variable duration for the inlet valves and others are limited to lower RPM ranges.
Some links to explore.
Siemens
http://www.sae.org/automag/toptech/02-2001/toptech5.htm
Camcon
http://www.manufacturingtalk.com/news/cmc/cmc101.html
Lotus
http://www.all4engineers.com/index.p...alloc=33/id=45
http://www.bmwworld.com/engines/valvetronic.htm
http://www.artificialmuscle.com/
http://www.manufacturingtalk.com/news/mij/mij114.html
http://www.findarticles.com/p/articl...0/ai_n15777158
http://www.findarticles.com/p/articl...16/ai_n6277206
VALVE SPRINGS
Valve springs are the primary limiting factor on engine speeds, and generate many unpleasant effects, such as harmonics and valve float. Without them there is relatively little friction in the valve train.
The push to create a camless engine misses the point. The springs are the problem, not the cam shafts.
Most of the systems described below still utilize springs with all their incumbent problems.
ELECTRO MECHANICAL
This method of valve control is often found in camless engine designs. A proponent of this technology is Valeo, which indicates that its design will be utilized in volume production in 2009.
http://www.valeo.com/automotive-supplier/Jahia/pid/1317
Some of the problems which may be encountered with this methodology are:
- Deceleration of the valve once set in motion is difficult to accomplish, and inadequate slowing down of the valve can cause significant deterioration of the valve seat and other parts. Utilizing springs to effect valve deceleration limits the engine to lower speeds and may still not effect a gentle landing of the valve on its seat at all engine speeds.
- Springs utilized in this type of system may require very careful balancing with the valve movement in order to achieve gentle valve seating at differing engine speeds. As the springs deteriorate, the valve mechanism may become unbalanced and ultimately lead to failure.
- The electromagnets will draw a significant amount of electrical energy, which may require a higher capacity alternator, which will in turn reduce the potential fuel efficiency of the engine.
- A powerful computer coupled with complex fast-acting control circuitry and devices will likely be necessary to control the valves in real time.
HYDRAULIC
This type of valve control has been advocated in the search for a camless engine. Sturman Industries, which incorporated its design into a large truck engine a number of years ago, is a proponent of this technology.
http://www.sturmanindustries.com/mai...eActuation.htm
Various methods have been explored to utilize hydraulic mechanisms to move the engine valves. Some claim to be successful at low engine speeds, but few claim to achieve that goal meaningfully at the higher RPM requirements of passenger vehicles..
Hydraulic systems suffer from 2 inherent problems :
1) The faster a liquid is moved, the more it tends to act like a solid. A fast-acting hydraulic system to activate automotive valves at the speeds required in passenger vehicles could require immense pressures, with all the incumbent problems, including the additional energy requirements of the hydraulic pump. Even if higher engine speeds were achieved, valve movement would likely be abbreviated and not fully follow the desired or optimum lift schedule.
2) Temperatures can vary seasonally over a wide range. The hydraulic medium could change viscosity as the temperatures change, which could cause variances in the system’s performance which may be difficult to control.
Utilizing valve springs to assist the hydraulic system may also prevent the engine attaining higher speeds.
In order to achieve gentle valve seating, hydraulic systems must be carefully controlled. This control may require the use of powerful computers and very precise sensors.
DESMODROMIC
This form of valve control utilizes camshafts but not conventional valve springs. A long-time proponent of this technology is Ducati, which has successfully used this methodology in their motorcycles.
http://www.ducati.com/
This methodology removes the valve spring limitation on engine RPMs. However, other factors such as the use of rocker arms to open and close the valves may have a limiting effect on performance.
A desmodromic system does not normally provide for positive seating of the valves, as they are for the most part held closed by gas pressures in the cylinder. The exception could be the exhaust valve, which may be partially open in the “closed” position during the intake stroke.
There are no known variable duration systems utilizing this methodology.
PNEUMATIC
Systems utilizing pneumatics to drive the engine valves would in all probability not be feasible because of their complexity and the very large amount of energy required to compress the air.
VARIANTS ON CURRENT CAM TECHNOLOGY
There are a number of mechanical valve operating systems based on traditional cam technology. Many rely on an offset gear to slow the cam as it opens the valve, thereby prolonging the valve-opening duration. This together with cam phasing provides a limited form of variable duration. An example of this technology is the K series engine produced by Rover.
http://www.sandsmuseum.com/cars/elis...ngine/vvc2.pdf
Problems with this methodology generally stem from the complexity and size of the units, the slow opening and closing of the valves, and the limited available variation in valve opening and closing times. Additionally, the valves may have to be lifted higher than their theoretical optimum height in order to achieve optimum gas flow.
Some examples of this methodology only provide variable duration for the inlet valves and others are limited to lower RPM ranges.
Some links to explore.
Siemens
http://www.sae.org/automag/toptech/02-2001/toptech5.htm
Camcon
http://www.manufacturingtalk.com/news/cmc/cmc101.html
Lotus
http://www.all4engineers.com/index.p...alloc=33/id=45
http://www.bmwworld.com/engines/valvetronic.htm
http://www.artificialmuscle.com/
http://www.manufacturingtalk.com/news/mij/mij114.html
http://www.findarticles.com/p/articl...0/ai_n15777158
http://www.findarticles.com/p/articl...16/ai_n6277206
03-05-2007 | 05:55 AM
#27
2nd Gear
Joined: Mar 2007
Posts: 2
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A workable system?
I addition to my post above, this site gives some interesting information for those interested in Variable Duration Valve Trains.
http://www.powertrainltd.com/camcont...esentation.pdf
This device appears to be the most promising to date however a quick glance indicates that the valve train limits the engine to a maximum of 6,000 - 6,700 RPM. This is calculated from their statement that they open and close a valve in 7 ms.
The calculation :-
8,000 RPM (claimed) is 2,880,000 degrees traversed per minute (8,000 * 360) or 48,000 degrees per second.
Crank degrees traversed in 1 ms = 48 (48,000/1000). Degrees traversed in 7 ms = 336 (7*48). This is unrealistic for any engine. 6,200 RPM gives a more realistic 260 degrees. However even this is misleading as at this engine speed the valve will have to start closing as soon as it is open causing a much less than optimum and abbreviated air intake.
Valves that open and close in fixed times do not have the flexibility required for optimizing engines at differing speeds. What is needed is a valve system that operates faster as the engine speed increases so giving more engine breathing time.
http://www.powertrainltd.com/camcont...esentation.pdf
This device appears to be the most promising to date however a quick glance indicates that the valve train limits the engine to a maximum of 6,000 - 6,700 RPM. This is calculated from their statement that they open and close a valve in 7 ms.
The calculation :-
8,000 RPM (claimed) is 2,880,000 degrees traversed per minute (8,000 * 360) or 48,000 degrees per second.
Crank degrees traversed in 1 ms = 48 (48,000/1000). Degrees traversed in 7 ms = 336 (7*48). This is unrealistic for any engine. 6,200 RPM gives a more realistic 260 degrees. However even this is misleading as at this engine speed the valve will have to start closing as soon as it is open causing a much less than optimum and abbreviated air intake.
Valves that open and close in fixed times do not have the flexibility required for optimizing engines at differing speeds. What is needed is a valve system that operates faster as the engine speed increases so giving more engine breathing time.
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