ICE rev??
 

Curious why the ice won't rev in park or neutral. No reason, I just wanted to know.

Roy

Re: ICE rev??
 

Roy:
My guess is since the ICE is controlled by a computer and it's only use is to supply power to either recharge the batteries or to drive the wheels as needed, there is no need to "REV" the ICE in neutral or park. This would only hurt FE.

Re: ICE rev??
 

It would also potentially destroy MG1 mechanically by over-revving it. If the car is stationary, MG1 spins at 3.6 times the speed of the ICE. This means that if the ICE gets much above 3000 rpm with the car stationary, you're getting into danger territory.

Stan

Re: ICE rev??
 

Roy:
Check this link out and you can see how the system works: http://eahart.com/prius/psd/

Re: ICE rev??
 

Thanks for the link. Pretty cool.

Roy

Re: ICE rev??
 

I've read of hybrid owners who "force charge" their cars (one foot on the gas and one on the brake while in drive) with no apparent mechanical damage. Although one person did report a pretty big increase in MG1 temp. The one thing it WILL ruin, and I can attest to this, is your FE. I tried it one time and my mpg dropped like I've never seen it drop before. Not something I would try again.

Re: ICE rev??
 

How did they measure the MG1 temperature? I've been wanting to be able to measure the MG1 and MG2 temperatures.

Re: ICE rev??
 

If you floor it, it does. At least the engine starts and revs. Never had the guts to hold it and see how high it will rev.

Later!

Dang

Re: ICE rev??
 

My old 2001 Honda Accord had rev limiter way back when and it wasn't even a hybrid , if you had it in park the engine would start cutting off fuel at around 2500-3000 RPM and would never go past 3000 (during driving max RPM was 6000), I guess to protect free wheeling engine from overspeeding which would be very easy with no load on it. Also TCH will spin the ICE when in park, at least mine does so in this regard it behaves exactly the same and it probably has rev limiter at around similar 2500-3000 RPM when parked.

Re: ICE rev??
 

LOL TCH — There's no problem running the ICE at moderate rpm in 'P', 'D', or 'B' while stationary, of course. And, if the NiMH and/or 12-V batteries aren't fully charged, there will be an electrical load on MG1 as it charges them, so that useful work will be done. However, I'm willing to bet that even then the ICE will not rev faster than 3000 rpm, and probably much less.

Stan

Re: ICE rev??
 

I really love this website! Some of the questions asked are quite creative. But I don't understand why someone would want to 'over-ride' car's computer by overreving the ICE or 'force charging' the batteries. Toyota has spent billions developing a car more advanced than anything I've ever driven before. I marvel at the way it works as intended.

When I was a kid I wondered what would happen if I put beans in my ears before I went swimming. I found out.

But keep those questions coming; I love reading them.

Re: ICE rev??
 

I believe the measurements were with a Miniscanner in the previous generation of the Prius. I'll bet the CAN-View would be able to do this on the newer models. I think us Camry owners are out of luck for now. We'll have to wait and see what changes are in store for the ScanGauge.
Stan-The people who used forced charging on the previous Prius were really testing MG1's limits. Wasn't MG1's max rotation 6500rpm back then?

Re: ICE rev??
 

LOL TCH — Yes, I think so. But our TCHs allow at least 10 000 rpm, and I think I read 14 000 somewhere. I'm sure Toyota won't allow you to rev the ICE so as to get MG1 anywhere near those limits, though. Forced NiMH battery charging is probably also possible in the TCH, but I haven't checked this out. I've never had the need to try it!

Stan

Re: ICE rev??
 

First of all you can't over-ride car's computer, at least I'm not aware of it and by pressing on accelerator when parked you simply ask computer for permission to spin up ICE, no harm done. You also can not over rev the engine, computer won't let you. As far as why? original poster had no particular reason, just an observation but I could find at least 4: to faster charge traction battery, to faster warm up the car in winter cold before driving, to check emissions and possibly to improve car's launch from dead stop. And regardless of anything else TCH behaves just like any other late model car with rev limiter watching over your shoulder at all times.

Re: ICE rev??
 

In my case I was just sitting waiting for my wife and pressed on the throttle, and was surprised the engine fired up. Wasn't trying to do anything, but it's interesting.

Reving the engine to charge the batteries seems a bit counter productive to best fuel economy, but maybe there is logic to this I don't quite see at the moment.

Later!

Dang

Re: ICE rev??
 

You guys asked for the reasons and I gave few, regardless if they make much sense or not. Also without actual testing it would be difficult to say at what RPM, charging traction battery is the most efficient, it could be that running engine at higher RPM could be more efficient than keeping it at idle, besides, pressing accelerator is the only way I know off to force charge battery without driving so for example you would want to fully charge traction battery before you go for 3 months vacation and instead of driving mindlessly around your block, you could charge it in your driveway.

Re: ICE rev??
 

Pete4 OK! Good answers but not necessarily accurate. If I'm not mistaken the TCH is fitted with a voltage regulater like most cars. As I recall, part of its purpose is to maintain a constant charge to the batteries regardless of engine speed. Reving to warm the engine faster can actually harm the engine by forcing cold antifreeze into a hotter than normal engine block.(a lesson I learned the hard way on my '54 Olds) Checking emmissions is a valid point but this is a partial zero emmissions system. Finally the MG1 puts out 199 lb-ft of torque immediately when you hit the gas pedal. That's enough to burn rubber if it wasn't for the ECVT tranny and the VDIM system. In fact that's one reason why they're necessary.

By the way, I wasn't flaming the poster. This IS a forum and I really enjoy checking in everyday.

Re: ICE rev??
 

Al Froio — The 12-V battery is charged by a dc-to-dc converter fed from the NiMH battery. This controls the state of charge of the 12-V battery. There's no "voltage regulator" per se. It's MG2 that is the powerful motor, not MG1. And, of course, its output torque is electrically variable under the control of the ECUs and inverter circuitry. It certainly doesn't "put(s) out 199 lb-ft of torque immediately when you hit the gas pedal."

Stan

Re: ICE rev??
 

SPL-- Thanks for the correction, MG2 provides the power, MG1 provides the charge. However, MG2 like any electric motor puts out full torque at ANY speed. The spec sheet in the Toyota Hybrid brochure states: "Electric motor power output 199 lb.-ft @ 0-1500 rpm (105 kw @ 4500 rpm).
My point about a voltage regulator (actually the Variable Voltage System) was that racing the ICE will not charge the batteries any faster than running the ICE at normal speed.

A great manual that covers all of the features on this great car is THE TOYOTA CAMRY NEW CAR FUNCTIONS GUIDE. I was able to download it a while ago on this site "list of pertainent TSBs"

Re: ICE rev??
 

Al Froio — I respectfully disagree. The ECU and inverter control logic vary both the motor voltage (and consequently the motor current and torque) and frequency (and consequently the motor speed) of the 3-phase ac power fed to/from the MGs. The torque and power specifications that you cite are MG2's maximum capabilities (in the same way that the ICE's maximum torque and power specifications do not imply that it always puts out these maximum numbers). MG2 might be able to put out its full torque over a wide speed range, but it is rarely (if ever) asked to do so. The MGs are used nowhere near their maximum limits most of the time. Indeed, I don't believe that MG2 can even be driven at its maximum rated 105 kW power by any combination of ICE and NiMH battery powers, under normal circumstances.

Thanks, but I already have the New Car Features Guide.

Stan

Re: ICE rev??
 

Stan has it right, but he did not re-mention one thing that was alluded to in his earlier post. Since the PSD cannot be uncoupled from the ICE at any time, the ratio between the ICE and MG1 must be a limiting factor for ICE RPM anytime MG2 is not turning. There is not such thing as only MG1 and the ICE "on line". Therefore, to protect MG1 from over rev, the ECU is going to limit ICE RPM. I would happliy take Stan's side on the bet that the ICE will not rev above 3000 or so when stationary, and probably a lot less.

Re: ICE rev??
 

Bob & Stan: Check out this link and you can see the relationship between the ICE, MG1, & MG2 as far as REV's and also speed and REV's. I have posted this earlier in this thread, sorry for the repeat if offends anyone.


http://eahart.com/prius/psd/

Re: ICE rev??
 

For your information, the formulas relating the ICE rpm (Ne), MG1 rpm (Ns), and MG2 rpm (N2, 2.478 times Nr, the ring-gear speed) is set by the tooth ratios of the gears in the two planetary-gear sets, and are:
Ne = 0.2778 Ns + 0.7222 Nr = 0.2778 Ns + 0.2914 N2,
while Nr is related to the road speed RS by
Nr = 28.2199 RS (for RS in km/h) = 45.4058 RS (for RS in miles per hour).
[These are deduced from the formulas I gave in the thread "Heretical Mode," posts #27 and 34.]

Since
power = (angular velocity) x torque
one can see from the specifications for MG2 [105 kW @ 4500 rpm; 270 Nm @ 0-1500 rpm] that:

• Maximum power of 105 kW @ 4500 rpm => torque of 700/pi = 223 Nm < maximum torque of 270 Nm
• Maximum torque of 270 Nm @ 1500 rpm => power of 13.5 pi = 42.4 kW << maximum power of 105 kW

So, you can't get the maximum torque at maximum rpm; and you can't get the maximum power at 1500 rpm. These are the maximum ratings for this motor. I think that the maximum torque is limited by the maximum current that it (and the inverter electronics) can safely handle; and the maximum power is limited by the maximum heating effect (product of voltage and current) that they can dissipate.

Stan

Re: ICE rev??
 

Exactly what I was going to say...............................

Re: ICE rev??
 

Wow! I bow to the superior knowledge of all you guys! I'm learning alot more than I ever thought I knew about my TCH. And all this because ROY wondered why he couldn't rev his ICE while in neutral.

I love this website!

From now on I'm going to rev up my engine to charge my batteries faster and get the heater going, then I'm going to pop it into Drive so I can avoid that 1/2 second of hesitation at the stoplight. I'm looking forward to developing a deep ongoing relationship with my Toyota Service Manager. Just kidding :-)