ICE (Internal Combustion Engine) technologies

Thread Starter

cmartinez

Joined Jan 17, 2007
8,276
Everybody's talking about EV's, Hybrids and battery technologies for transportation. But it draws my attention that technology for internal combustion engines is also always improving and evolving and barely anyone (other than us, nerds) takes notice. Here's an interesting proposal:

 

BobTPH

Joined Jun 5, 2013
9,132
Interesting idea. Would certainly enable higher RPM operation since, as I understand it, the valves are the limiting factor.
 

Thread Starter

cmartinez

Joined Jan 17, 2007
8,276
Interesting idea. Would certainly enable higher RPM operation since, as I understand it, the valves are the limiting factor.
I hadn't realized how much of an ICE design and limitations (and even size) revolves around the poppet valves
 

GetDeviceInfo

Joined Jun 7, 2009
2,196
at The beginning of the video, he tries to show how hard it is to compress the valve, but doesn’t mention how hard it is to restrain the decompression. In engines with few valves, that decompression will spin the engine. Divide the rotation up with many valve springs and see how relatively easy it is to drive the cam assembly. A good indication is that valve train assemblies don’t require cooling, other than that from lubrication. The rotary valve concept has a major hurdle, that being temperature change of it’s components from ambient to superheated exhaust. Rotational members within a housing are largely defined by clearances, directly affected by heat. Interesting as a concept, but disproven by years of practical applications.
 

geekoftheweek

Joined Oct 6, 2013
1,240
Divide the rotation up with many valve springs and see how relatively easy it is to drive the cam assembly.
Sort of true for bigger engines, but say a four cylinder is going to actuate valves during the same 180 degrees of crank rotation at the same time with no overlap. You will get some balancing effect with say V8's and larger, but for the smaller engines it doesn't happen.

Edit:

Coolant also passes through the head and around the top of the combustion chamber so there is going to be a bit of cooling also.
 

crutschow

Joined Mar 14, 2008
34,680
This is one of the more interesting new engine developments I have seen.
It's rather an inside-out Wankel which solves some of the Wankel problems like efficiency, and the moving seals which are now stationery.
Looks great if it can meet the hype without any significant hidden flaws.
 
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Thread Starter

cmartinez

Joined Jan 17, 2007
8,276
That scenario is abnormal, which no one intentionally does, so it's not worth the cost of protecting against it.
Well in my case, it is.

I'm currently working on a project (which details I'm afraid I can't disclose here) that requires effectively disconnecting a car's battery when the car is not in use. For that purpose, I'm planning on using these switches, which are widely used in the maritime industry.

My one worry now, is that some idiot might eventually decide to turn the switch into the disconnected position while the engine is still running.
 

crutschow

Joined Mar 14, 2008
34,680
My one worry now, is that some idiot might eventually decide to turn the switch into the disconnected position while the engine is still running.
Then to make it idiot proof, you would need to interlock the switch so it couldn't be turned off or else bypassed with a relay when the engine is running.

Suddenly disconnecting the battery will lead to a large voltage spike (load-dump transient, below) from the alternator during the time it takes to regulate its voltage after the battery charging current is suddenly stopped.
Reconsidering my previous comment, I think that generally car electronics are designed to tolerate this voltage spike, so perhaps you don't need any additional protection.

1712117913036.png
 

Thread Starter

cmartinez

Joined Jan 17, 2007
8,276
Then to make it idiot proof, you would need to interlock the switch so it couldn't be turned off or else bypassed with a relay when the engine is running.

Suddenly disconnecting the battery will lead to a large voltage spike (load-dump transient, below) from the alternator during the time it takes to regulate its voltage after the battery charging current is suddenly stopped.
Reconsidering my previous comment, I think that generally car electronics are designed to tolerate this voltage spike, so perhaps you don't need any additional protection.

View attachment 319023
I sure hope you're right ... I'm going to include a disclaimer in my proposal, though, to be on the safe side. I just hope it doesn't scare away my client.
 

crutschow

Joined Mar 14, 2008
34,680
You could also put a power Zener of a few volts back-to-back with a power diode across the switch to absorb any transient voltage that is greater than the Zener voltage plus the diode forward voltage above the battery voltage (below):

1712119821151.png
 

Thread Starter

cmartinez

Joined Jan 17, 2007
8,276
You could also put a power Zener of a few volts back-to-back with a power diode across the switch to absorb any transient voltage that is greater than the Zener voltage plus the diode forward voltage above the battery voltage (below):

View attachment 319028
Yeah, the thought of a TVS has already crossed my mind. It would have to be one big MF, in my vey humble opinion.
 

Sensacell

Joined Jun 19, 2012
3,475
Then to make it idiot proof, you would need to interlock the switch so it couldn't be turned off or else bypassed with a relay when the engine is running.

Suddenly disconnecting the battery will lead to a large voltage spike (load-dump transient, below) from the alternator during the time it takes to regulate its voltage after the battery charging current is suddenly stopped.
Reconsidering my previous comment, I think that generally car electronics are designed to tolerate this voltage spike, so perhaps you don't need any additional protection.

View attachment 319023
This is interesting! I have heard the term "Load Dump" before in the automotive context, but the exact cause was never clearly explained.

Now I get it, the response time of the alternator regulation system is slow, when the battery impedance is removed, the voltage soars!

One of those things that once defined seems so obvious.
 

crutschow

Joined Mar 14, 2008
34,680
Yeah, the thought of a TVS has already crossed my mind. It would have to be one big MF, in my vey humble opinion.
It would have to handle the alternator charging current for about a half second, based on the graphic I posted, but its voltage rating would only need to be perhaps 2-3V (just enough to keep the normal alternator voltage from charging the battery), minimizing the energy dissipated.
 

schmitt trigger

Joined Jul 12, 2010
918
I worked in the automotive electronics industry for 15 years. I can tell you that those products are fully characterized and protected for load dumps and many other abnormal events.
Having said this, automotive electrical systems are evolving much faster than what the SAE and IEC can develop standards for.
I can tell you for instance, that creating a load dump condition while the engine and A/C cooling fans were running, several load dump-compliant modules would sometimes be damaged.
Thus, you should both write a disclaimer AND provide an additional level of protection.
 

crutschow

Joined Mar 14, 2008
34,680
You could also likely use three ≥100A standard (not Schottky) silicon diodes in series to perform the protection function.
 

Thread Starter

cmartinez

Joined Jan 17, 2007
8,276
You could also likely use three ≥100A standard (not Schottky) silicon diodes in series to perform the protection function.
Mind elaborating? .... wouldn't that only protect against reverse voltage spikes and not an under-regulation transient?
 

crutschow

Joined Mar 14, 2008
34,680
Mind elaborating? .... wouldn't that only protect against reverse voltage spikes and not an under-regulation transient?
No.
The diode's polarity (D1) is cathode towards the battery, so it will conduct for any positive transients from the alternator, but block any current from the battery.
 
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