System of limited slip differentials with two power sources

In summary, this system has a problem in that the RIC will act as a fulcrum that may effectively reverse the drive from the electric motors to the front axle. Locking the middle diff will eliminate the problem.
  • #1
howellrh
1
0
My first ever post here, so hello world!
So I've attached an image of a conventional 4x4 system with one RIC engine and LSDs for all wheels so that all four wheels can be driven, or just one depending on conditions. the front/rear LSD may in fact be locked, but that isn't particularly important...
RIC + LSDs.gif

So if the front axle is at the bottom of the page, and the rear axle is at the top (the car is driving down your screen) and i added two electric motors where the rear brakes would usually go, then how would the system behave under acceleration? I know that removing the brakes isn't a great idea in real life, but for the purposes of this question its easier to describe it that way.
RIC + LSDs + Motors.gif

If you want numbers to play with then let's say the engine is 100kWm and the electric motors are 30kWm each and the LSDs can be whatever type you thing is best for this scenario
All the tyres are the same tread and grip, and we are assuming that the vehicle is on a level homogeneous road surface to keep it to the problem in hand.
My first conclusion on this problem is that the LSDs will sort themselves out (provided they have the right settings - which I can't define) and 1/4 of the overall 160kWm (that's 40kWm) would be applied to each wheel. I just can't decide if in reality the front/read LSD would think that the rear wheels were slipping and send all the power to the front initially, until the LSDs begin to limit the slip in the front/back...
also, what effect would locking the front/rear diff have? would it be better?
thanks to all for your help!
 
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  • #2
There is a problem. The RIC will act as a fulcrum that may effectively reverse the drive from the electric motors to the front axle.
Locking the middle diff will eliminate the problem.
 
  • #3
Baluncore said:
There is a problem. The RIC will act as a fulcrum that may effectively reverse the drive from the electric motors to the front axle.
Locking the middle diff will eliminate the problem.

howellrh said:
My first ever post here, so hello world!
So I've attached an image of a conventional 4x4 system with one RIC engine and LSDs for all wheels so that all four wheels can be driven, or just one depending on conditions. the front/rear LSD may in fact be locked, but that isn't particularly important...
View attachment 84856
So if the front axle is at the bottom of the page, and the rear axle is at the top (the car is driving down your screen) and i added two electric motors where the rear brakes would usually go, then how would the system behave under acceleration? I know that removing the brakes isn't a great idea in real life, but for the purposes of this question its easier to describe it that way.
View attachment 84854
If you want numbers to play with then let's say the engine is 100kWm and the electric motors are 30kWm each and the LSDs can be whatever type you thing is best for this scenario
All the tyres are the same tread and grip, and we are assuming that the vehicle is on a level homogeneous road surface to keep it to the problem in hand.
My first conclusion on this problem is that the LSDs will sort themselves out (provided they have the right settings - which I can't define) and 1/4 of the overall 160kWm (that's 40kWm) would be applied to each wheel. I just can't decide if in reality the front/read LSD would think that the rear wheels were slipping and send all the power to the front initially, until the LSDs begin to limit the slip in the front/back...
also, what effect would locking the front/rear diff have? would it be better?
thanks to all for your help!
Suppose the RIC is stopped and the rear LH wheel is on solid ground. If the RH rear wheel is on ice, I think the motor will cause it to spin.
By the way, I have drawn myself an electrical analogue of the set up, using transformers for the differentials. When a differential locks, it seems to be equivalent to grounding the transformer centre tap.
 
  • #4
tech99 said:
By the way, I have drawn myself an electrical analogue of the set up, using transformers for the differentials.
Can you please attach a copy of your model to a post.
tech99 said:
When a differential locks, it seems to be equivalent to grounding the transformer centre tap.
I would have thought that pinion drive would be through the centre tap with a resistor between the opposite ends to simulate a LSD. A short between the opposite ends would emulate a locked diff.
 
  • #5
Baluncore said:
Can you please attach a copy of your model to a post.

I would have thought that pinion drive would be through the centre tap with a resistor between the opposite ends to simulate a LSD. A short between the opposite ends would emulate a locked diff.
I have tried to attach my diagram of the electrical analogue. Sorry if it does not work.
 

Attachments

  • differential (2).jpg
    differential (2).jpg
    27.6 KB · Views: 471
  • #6
This is my transformer analogy. Torque for different motors is identified by different mutually prime frequencies.
Change the value of R_lock to lock the centre diff.
 

Attachments

  • AWD.png
    AWD.png
    10.4 KB · Views: 476

FAQ: System of limited slip differentials with two power sources

1. What is a system of limited slip differentials with two power sources?

A system of limited slip differentials with two power sources is a type of drivetrain technology used in vehicles, particularly in off-road and high-performance vehicles. It consists of two separate power sources, usually an internal combustion engine and an electric motor, that work together to power the vehicle's wheels and provide better traction and handling.

2. How does this system work?

This system works by distributing power between the two power sources and the wheels of the vehicle. When one of the wheels starts to slip, the system adjusts the power distribution to the other wheel with more traction, allowing the vehicle to maintain better control and stability on different types of terrain.

3. What are the benefits of using this type of system?

The main benefits of using a system of limited slip differentials with two power sources are improved traction and handling. This can be especially useful in off-road and high-performance driving situations, as well as in inclement weather conditions. Additionally, the use of an electric motor can also provide increased fuel efficiency and reduced emissions.

4. Are there any drawbacks to this system?

One potential drawback of this system is its complexity, which can lead to higher costs for both installation and maintenance. Additionally, some drivers may find the handling characteristics of the vehicle to be different from traditional vehicles, which may require some adjustment.

5. Is this system widely available in vehicles?

Currently, this system is not as widely available as other drivetrain technologies, but it is becoming increasingly common in high-end and luxury vehicles. As technology continues to advance, we may see this type of system become more prevalent in different types of vehicles in the future.

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