AWD Hybrid
07-13-18, 04:24 PM
#1
Racer
Thread Starter
AWD Hybrid
So I have a question.
How exactly is RPM synchronized between the front and rear PSDs in an AWD hybrid? As rear drive is, basically, a small version of the front power split device, with its own motor. So they somehow have to be in-sync with the front wheels, when all four engage.
Presuming, it's all based on ABS sensors acting as RPM monitors and then adjusted electronically? I have never ever noticed a slightest glitch in AWD operation in my HiHy.
How exactly is RPM synchronized between the front and rear PSDs in an AWD hybrid? As rear drive is, basically, a small version of the front power split device, with its own motor. So they somehow have to be in-sync with the front wheels, when all four engage.
Presuming, it's all based on ABS sensors acting as RPM monitors and then adjusted electronically? I have never ever noticed a slightest glitch in AWD operation in my HiHy.
07-15-18, 03:37 PM
#2
Why would they have to be in sync?
As far as I know an AWD version just has an electric motor that applies power to the rear wheels under heavy acceleration or when in Snow Mode. I am unaware that the computer monitors rpms and compensates if it senses one axle slipping more than the other. In a conventional AWD if one axle was slipping then all the power would go to that axle unless some sort of positraction mechanism prevented it. But here there are two separate motors; if one was slipping it wouldn't affect the other motor, right?
As far as I know an AWD version just has an electric motor that applies power to the rear wheels under heavy acceleration or when in Snow Mode. I am unaware that the computer monitors rpms and compensates if it senses one axle slipping more than the other. In a conventional AWD if one axle was slipping then all the power would go to that axle unless some sort of positraction mechanism prevented it. But here there are two separate motors; if one was slipping it wouldn't affect the other motor, right?
07-15-18, 04:32 PM
#3
Lexus Champion
So I have a question.
How exactly is RPM synchronized between the front and rear PSDs in an AWD hybrid? As rear drive is, basically, a small version of the front power split device, with its own motor. So they somehow have to be in-sync with the front wheels, when all four engage.
Presuming, it's all based on ABS sensors acting as RPM monitors and then adjusted electronically? I have never ever noticed a slightest glitch in AWD operation in my HiHy.
How exactly is RPM synchronized between the front and rear PSDs in an AWD hybrid? As rear drive is, basically, a small version of the front power split device, with its own motor. So they somehow have to be in-sync with the front wheels, when all four engage.
Presuming, it's all based on ABS sensors acting as RPM monitors and then adjusted electronically? I have never ever noticed a slightest glitch in AWD operation in my HiHy.
the heavy snow on the road but Lexus when I tried back up, it was not much of a help at all. Car wouldn't pull me out, as I spin the wheel rear end was lifting up instead of digging into snow. . All vehicles had very good winter tires. This winter I am going to try 2015 Mercedes ML550 to see what it can do in deep snow.
07-15-18, 08:54 PM
#4
Racer
Thread Starter
Because you can't really drive a car when front and rear axles wheels spin at different speeds. And, without mechanical transfer case+driveshaft, they got to be synched somehow.
Ad hoc, my HiHy AWD took me through any ice and snow up hills without a glitch. but I do know how to drive on snow and ice.
Also, AWD does not kick in only in snow and ice. It actually does so under heavy load. That said, just imagine going up hard serpentine, like I do daily, with front and rear end spinning at various speeds. Hope, this helps to understand why.
Ad hoc, my HiHy AWD took me through any ice and snow up hills without a glitch. but I do know how to drive on snow and ice.
Also, AWD does not kick in only in snow and ice. It actually does so under heavy load. That said, just imagine going up hard serpentine, like I do daily, with front and rear end spinning at various speeds. Hope, this helps to understand why.
07-16-18, 08:42 AM
#5
I have been watching youtube videos, and as far as I can tell, its almost like the lexus is all electric motor driven, and the Internal Combustion Engine (ICE) either supplies power to the motor or to the battery, or both. I do not think it is responsible for a physical connection to the wheels. It seem to be all software, keeping everything in synced, the ICE, MR1, MR2, MR3. It seems pretty sophisticated. Google Hybrid Synergy Drive.
The Synergy Drive is a drive-by-wire system with no direct mechanical connection between the engine and the engine controls: both the gas pedal/accelerator and the gearshift lever in an HSD car merely send electrical signals to a control computer.
07-25-18, 11:55 AM
#6
I have been watching youtube videos, and as far as I can tell, its almost like the lexus is all electric motor driven, and the Internal Combustion Engine (ICE) either supplies power to the motor or to the battery, or both. I do not think it is responsible for a physical connection to the wheels. It seem to be all software, keeping everything in synced, the ICE, MR1, MR2, MR3. It seems pretty sophisticated. Google Hybrid Synergy Drive.
The drive by wire is describing the pedal is electronically sensed and then the computer determines how much response (i.e.how much energy to send to the electric motors (mg1/mg2/mg3) and also when to turn on the ICE). Normally cars have a mechanical wire that pulls the throttle body that controls the response of the engine.
This guy teaches about automotive (esp on hybrids) at Weber State University
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