9 SPD DCT with Reverse?

[Valkyrie Pilot]

Was thinking about the way Koenigsegg doesn't use a tranny (the one with gears not the person) with its hybrid car and thought the NSX might do without a reverse gear since it has the TMU.

I haven't looked but I am guessing they have a reverse gear. But if that is true, wouldn't it be a cleaner, and lighter design to forgo that gear since they can just use the TMU for backing up when its needed?

What am I missing here?

 

[chrisn]

Interesting point. I see no reason why they couldn't just use FWD for reverse, although it would be nice to have AWD in reverse for traction. Also, there might be edge cases where you don't have enough battery juice for the power and duration of the reversing maneuver that is needed. Not sure if the ICE can charge the batteries with the RWD in "neutral."

On second thought, since they have a version without the electrics, they must have a "real" reverse gear in the DCT.

 

[Jinks]

I'm not sure exactly how electric motors in cars work but with AC voltage you usually have to swap a phase of power to get a motor to spin in the opposite direction. But with DC motors you can just reverse polarity to get the same affect right?

 

[Tom239]

I'm not sure exactly how electric motors in cars work but with AC voltage you usually have to swap a phase of power to get a motor to spin in the opposite direction. But with DC motors you can just reverse polarity to get the same affect right?

Yes swapping polarity of a DC motor changes the direction, but the NSX is
not using DC motors.

The NSX drive motors (the one in the back and the two in front) are synchronous
AC motors with permanent magnets in the the rotors. Synchronous means that
the speed of the motor is in sync with the AC supply; one revolution is an integral
number of AC cycles. That means the electronics driving the motors in the NSX
must continuously adjust the frequency of the AC applied to each motor to
correspond to the motor's speed at each moment. The control electronics can
run the motor in either direction.

 

[JD Cross]

Yes swapping polarity of a DC motor changes the direction, but the NSX is
not using DC motors.The NSX drive motors (the one in the back and the two in front) are synchronous
AC motors with permanent magnets in the the rotors. Synchronous means that
the speed of the motor is in sync with the AC supply; one revolution is an integral
number of AC cycles. That means the electronics driving the motors in the NSX
must continuously adjust the frequency of the AC applied to each motor to
correspond to the motor's speed at each moment. The control electronics can
run the motor in either direction.

I have a question off the OP transmission topic.
The NSX driveline ecu needs to match ICE, rear electric motor and two front electric motors.
This is well beyond my comprehension of computers and electrics.
Do you think there's a master map for voltage and frequency to each motor to correspond to all the various inputs from the engine, wheel sensors etc.
It must be enormously complex software to make it as seamless as it's been reported.

 

[Jinks]

Yes swapping polarity of a DC motor changes the direction, but the NSX is
not using DC motors.

The NSX drive motors (the one in the back and the two in front) are synchronous
AC motors with permanent magnets in the the rotors. Synchronous means that
the speed of the motor is in sync with the AC supply; one revolution is an integral
number of AC cycles. That means the electronics driving the motors in the NSX
must continuously adjust the frequency of the AC applied to each motor to
correspond to the motor's speed at each moment. The control electronics can
run the motor in either direction.

Excellent history lesson. So theoretically the Nsx motors are VFD controlled? We started rolling out variable frequency drives in all of our compressor and fan motors technology in the commercial HVAC/R trade a few years back. They are very complex at first, but in the ending result they are quite brilliant. Not only does it control the motor via frequency but it also monitors a ton of specs from the motor itself. But, wait a minute. The motors in hybrid cars are alternating current? Or is it just limited to the Nsx?

- - - Updated - - -

Oh and I apologize to the OP for taking the thread a lil south. I am just new to hybrid tech in vehicles and it interests me.

 

[MasterNSXTech]

To answer the OP, yes our 9DCT has a reverse gear.

 

[Tom239]

Excellent history lesson. So theoretically the Nsx motors are VFD controlled? We started rolling out variable frequency drives in all of our compressor and fan motors technology in the commercial HVAC/R trade a few years back. They are very complex at first, but in the ending result they are quite brilliant. Not only does it control the motor via frequency but it also monitors a ton of specs from the motor itself. But, wait a minute. The motors in hybrid cars are alternating current? Or is it just limited to the Nsx?

The NSX motors are not unique. Most hybrids use similar motors (synchronous AC with
permanent magnet rotors). The same device operates as either a motor or a generator.
Tesla is different; they are using AC induction motors in the Roadster and Model S.

Even if the motor is called "brushless DC", the windings of the motor are not getting DC.
There's commutator or inverter electronics between the DC source and the motor windings.
From the Wikipedia article "Brushless DC electric motor":
"High power brushless motors are found in electric vehicles and hybrid vehicles.
These motors are essentially AC synchronous motors with permanent magnet rotors."
I give Honda credit for calling them AC synchronous motors--that's the straightforward
description of what they are.

 

[Jinks]

The NSX motors are not unique. Most hybrids use similar motors (synchronous AC with
permanent magnet rotors). The same device operates as either a motor or a generator.
Tesla is different; they are using AC induction motors in the Roadster and Model S.

Even if the motor is called "brushless DC", the windings of the motor are not getting DC.
There's commutator or inverter electronics between the DC source and the motor windings.
From the Wikipedia article "Brushless DC electric motor":
"High power brushless motors are found in electric vehicles and hybrid vehicles.
These motors are essentially AC synchronous motors with permanent magnet rotors."
I give Honda credit for calling them AC synchronous motors--that's the straightforward
description of what they are.

I have some new material to read up on.

 

[Valkyrie Pilot]

To answer the OP, yes our 9DCT has a reverse gear.

Ok thanks. But why have it?

If it can handle all electric operation for "Quiet" mode up to 40 mph, then it sure does seem like it could handle reverse long enough to finish a three point turn or parallel park.

I seem to recall that the Accord Hybrid does without a transmission so there seems to be a precedent for it within Honda.

- - - Updated - - -

Yes swapping polarity of a DC motor changes the direction, but the NSX is
not using DC motors.

The NSX drive motors (the one in the back and the two in front) are synchronous
AC motors with permanent magnets in the the rotors. Synchronous means that
the speed of the motor is in sync with the AC supply; one revolution is an integral
number of AC cycles. That means the electronics driving the motors in the NSX
must continuously adjust the frequency of the AC applied to each motor to
correspond to the motor's speed at each moment. The control electronics can
run the motor in either direction.

That's good to hear but only increases my dismay!

 

[JD Cross]

Ok thanks. But why have it?

Maybe if you've run the hybrid battery to zero at the track and need to back up?
Or had a hybrid battery failure?

 

[MasterNSXTech]

Ok thanks. But why have it?

If it can handle all electric operation for "Quiet" mode up to 40 mph, then it sure does seem like it could handle reverse long enough to finish a three point turn or parallel park.

The TMU is powerful enough to move the vehicle on flat road at that speed. But suppose you have a situation where you had to back up a steep driveway (probably not given the pretty flat approach angle clearance)? TMU might not have enough power to push a nearly two ton car up that grade.

 

[Tom239]

The TMU is powerful enough to move the vehicle on flat road at that speed. But suppose you have a situation where you had to back up a steep driveway (probably not given the pretty flat approach angle clearance)? TMU might not have enough power to push a nearly two ton car up that grade.

You beat me to it, I was going to mention the need to go uphill
Not just driveways, but also if you have to yield to uphill traffic on
a road too narrow for both of you. The driver pointed downhill
backs up until there's a spot that's wide enough. I've lived in a
neighborhood with steep hills where this was a routine occurrence.

I think other people have hit on the key points. The traction advantage
of AWD Is a plus even if the front motors have the juice to do it all
on their own. And having reverse in the transmission means it
doesn't have to be reworked for a future electric-free model.

And really, how much weight would you save by leaving out
a reverse gear in the transmission?

 

[chrisn]

FYI, car works in EV mode in reverse, but is pretty eager to fire up the ICE on even modest slopes/grades.

 

[Valkyrie Pilot]

FYI, car works in EV mode in reverse, but is pretty eager to fire up the ICE on even modest slopes/grades.

Ok thanks, that's interesting to know. So you can parallel park in EV mode without the ICE?

 

[chrisn]

Yes, if you feather the throttle. I assume it used the fronts for EV in reverse until ICE fires up. Transition is very smooth. Is the rear EV motor used in EV-only mode ever? My guess would be "no." The transitions among the powerplants is so smooth that it is hard to tell on a high grip surface.

I've managed to cruise at 35-37MPH in EV only on flat ground. EV mode kicks in during throttle-off decen at around 40, but I have not been able to accelerate to 40 without ICE kicking it. Just kind of fun playing with.

 

[Gadgetman]

Just to add info,
Honda added a Reverse to the Gold Wing in 1988 when it upgraded to 1500 cc 6cyl.
The neat trick they did was a reverse lever near your left thigh disengaged the starter motor from tranny and used it to move the bike.
The bike had to be in neutral vs clutch in, engine had to be running to unsure enough juice and the speed was governed at around 1mph. The wings still have it today but newer 1800's do disengage/engage electrically via a push button on right handgrip vs mechanical lever.
So they did the tech with only elec reverse years ago. But I think ICE and a reverse gear make more sense in a car... Plus elec for AWD if needed.