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:

 

Interesting idea. Would certainly enable higher RPM operation since, as I understand it, the valves are the limiting factor.

 

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

 

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.

 

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.

 

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.

 

Here is something that I did no know:

Your battery does more than just provide electricity. It also shorts AC, spikes and transients to ground. Removing the battery from the circuit allows those spikes and transients to travel around, endangering every semiconductor circuit in your car. The ECU, the speed sensitive steering, the memory seat adjustments, the cruise control, and even the car's stereo.

I would've thought that all modern cars would have a snubber circuit to avert this scenario?

 

Here is something that I did no know:

Your battery does more than just provide electricity. It also shorts AC, spikes and transients to ground. Removing the battery from the circuit allows those spikes and transients to travel around, endangering every semiconductor circuit in your car. The ECU, the speed sensitive steering, the memory seat adjustments, the cruise control, and even the car's stereo.

I would've thought that all modern cars would have a snubber circuit to avert this scenario?

That scenario is abnormal, which no one intentionally does, so it's not worth the cost of protecting against it.

 

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.

 

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.

 

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.

 

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):

 

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.

 

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.

 

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.

 

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.

 

AND provide an additional level of protection.

Such as the one suggested by crutschow?

 

You could also likely use three ≥100A standard (not Schottky) silicon diodes in series to perform the protection function.

 

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?

 

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.