Acura's Ferromagnetic Oil: Fact or Fiction?

[CINA]

I searched around the forum and found no mention of this so I figured I'd bring it up. Acura has been airing these commercials ( http://www.youtube.com/watch?v=rnZ4EyKrLAI" ) that claim to use a ferromagnetic liquid instead of oil and then claim that it improves handling.

Is any of this true? I know very little about cars, but it seems like a crock to me. Why would you need magnetic oil that responds to an "electromagnetic charge"? Why would engine oil improve handling?

Thoughts?

EDIT: Apparently it is suspension oil, but still.

 

[Ivan Seeking]

There have always been two competing goals for auto suspension systems: A soft suspension is needed for a smooth ride, and a stiff suspension system is needed for high performance. It sounds like this ferromagnetic fluid suspension, which is similar to one used by Audi, seeks to satisfy both requirements.

Acura fitted the MDX with magnetic suspension technology, similar to that used by Audi. The suspension has electromagnetic coils wrapped around shocks filled with an iron-enriched fluid. When those coils power up, the magnetic fields make the fluid become more viscous. But rather than just making the suspension more rigid, a computer analyzes the MDX's roll and yaw, along with other factors, and constantly adjusts the power in the coils to actively counteract roll...

http://reviews.cnet.com/suv/2010-acura-mdx/4505-10868_7-33999811-2.html

Ferromagnetic fluids have been around since I think the late 1970s. I remember first reading about it in the early 80s. At the time, I was going to investigate various potential applications for the technology, but the fluids were tremendously expensive. The particles [iron particles in the ferrofluid] used are so small that they are kept in suspension by Brownian motion.

 

[xxChrisxx]

It's not engine oil, it's the oil in the damper (shock absorber) they've replaced. As Ivan's quote shows it's to provide some measure of active damping by control of viscosity.

Other systems use regular oil and just control the flow, but this only alters the stiffness of the damper. Other systems do away with springs and dampers altogether and replace them with hydraulic actuators (early 90's F1 cars and Bose used this method).

 

[Gokul43201]

Haven't read any of the links, but it seems like they are using a MR (magnetorheological) fluid (not necessarily a ferrofluid). This is not implausible, but the thing that the fluid responds to is a magnetic field, not quite an "electromagnetic charge".

PS: See the wiki on magnetorheological fluid.

 

[Ivan Seeking]

Haven't read any of the links, but it seems like they are using a MR (magnetorheological) fluid (not necessarily a ferrofluid). This is not implausible, but the thing that the fluid responds to is a magnetic field, not quite an "electromagnetic charge".

PS: See the wiki on magnetorheological fluid.

Yes, I didn't recall reading about a change in viscosity in ferrofluids subject to magnetic fields, but it has been almost thirty years, so memory may be at fault.

I think one of the first industrial applications for ferrofluids was to make a floating bearing.

I do seem to recall specifically that 10 mL of the stuff was about $100. Presumably the price has dropped dramatically since then.

 

[mugaliens]

It's simply nano-sized ferric particles small enough to be kept in suspension via Brownian motion. It does have friction-reducing properties, and when used in conjuction with a strong enough magnetcs, can allow them to glide across surfaces.

If it's being used to "improve handing characteristics," I suspect it's in the steering linkaga, but http://www.acura.com/Features.aspx?model=ZDX&modelYear=2010&context=Performance#super_handling_allwheel_drive". It appears they're achieving their claims by means of good engineering, not because of some overhyped properties of a fluid.

 

[pantaz]

They seem to be using ferrofluid in the suspension dampers. From http://www.acura.com/Features.aspx?model=ZDX&modelYear=2010&context=Performance#integrated_dynamics_system":

The available Integrated Dynamics System (IDS) can adjust suspension stiffness in a split second, based on driving conditions. This allows the ZDX to remain comfortable during highway cruising, yet firm when the road requires high-performance handling. In addition, the driver can adjust the suspension and steering feel through the Sport and Comfort settings.

• The dampers—also known as shock absorbers—are filled with a fluid that significantly thickens in the presence of a magnetic field. The stronger the field, the stiffer the damper.
• Each damper can adjust from soft to race-car stiff in as little as five milliseconds.
• The Sport setting creates a firmer baseline for the dampers while they continue to adjust according to conditions. Likewise, the setting reduces overall power assist to the steering system for increased road feel, though the assist continues to increase at lower speeds.

 

[mugaliens]

They seem to be using ferrofluid in the suspension dampers. From http://www.acura.com/Features.aspx?model=ZDX&modelYear=2010&context=Performance#integrated_dynamics_system":

The available Integrated Dynamics System (IDS) can adjust suspension stiffness in a split second, based on driving conditions. This allows the ZDX to remain comfortable during highway cruising, yet firm when the road requires high-performance handling. In addition, the driver can adjust the suspension and steering feel through the Sport and Comfort settings.

• The dampers—also known as shock absorbers—are filled with a fluid that significantly thickens in the presence of a magnetic field. The stronger the field, the stiffer the damper.
• Each damper can adjust from soft to race-car stiff in as little as five milliseconds.
• The Sport setting creates a firmer baseline for the dampers while they continue to adjust according to conditions. Likewise, the setting reduces overall power assist to the steering system for increased road feel, though the assist continues to increase at lower speeds.

Ahh... Now this makes sense! Since the 70s, a lot of attempts have been made to incorporate active dampening in the suspension systems. Most have focused on simple electrodynamics (electromagnetic coils acting against magnets in the suspension system), but the feedback cycles were stymied back then by heat loss and computer systems which simply couldn't keep up with the dynamic changes.

Using a ferromagnetic fluid in the suspension would provide some significant advantages over simple electrodynamics, not the least of which would be less thermal degredation. Combined with both a more predictable model and much faster computers and sensors, I'm thinking the concept of affordable, and realistic active/dynamic suspension has arrived!

Go Acura!

 

[Moonbear]

Wow! This might be the first thread I've ever read in this section with a product claim that has been defended as credible. I never knew about this type of suspension system before, but this is pretty cool.