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Never felt this before, I'm sure this is absolutely normal.

I was coasting thru a parking lot and had foot on brake lightly when i shifted out of drive into neutral, to backup and grab a parking spot. Doing this caused regen to disengage and the brakes to engage. Its a weird feeling, absolutely normal but you can feel the pads grip the rotor.

Anyone else experience this?

Gen1 Volt. Speed was about 7-10mph range.
 

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When the trans is in neutral, it can no longer regen since the link between the wheels and the motors inside the transmission has been disconnected. This would ne a normal condition.
 

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Normal and a good way to clean your rear pads and rotors.
 

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When the trans is in neutral, it can no longer regen since the link between the wheels and the motors inside the transmission has been disconnected.
This isn't right. There's no mechanical change inside the drive unit when "shifting" into N. It's simply electronic/software. [Edit: Actually, this turned out to be false. (Oops!) See following posts.]

But, yes, regen is disengaged in N and the Volt defaults to mechanical brakes.
 

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According to the GM service manual operation, all clutches are off in park and in neutral. As far as I can tell, the motors should not rotate from the wheels moving. I may be wrong but that makes sense to me.

Neutral Engine Off
When the gear selector lever is moved to the Neutral (N) position, the hydraulic and electrical system operation is identical to Park (P) range.

Park Engine Off
When the gear selector lever is in the Park (P) position and the internal combustion engine is OFF, the auxiliary fluid pump is commanded ON and line pressure is directed to the pressure regulator valve.

Fluid Pressure Directed in Preparation for a Shift
Variable Low and 1-2 Reverse Clutch Regulator Valve

Line or auxiliary line fluid is routed through orifice #25 to the variable low and 1-2 reverse clutch regulator valve in preparation for a shift.


Variable Hi and 2-3-4 Clutch Regulator Valve

Line or auxiliary line fluid is routed through orifice #23 to the variable hi and 2-3-4 clutch regulator valve in preparation for a shift.


1-3 Reverse Clutch Regulator Valve

Line or auxiliary line fluid is routed through orifice #24 to the 1-3 reverse clutch regulator valve in preparation for a shift.


Dampener Bypass Clutch Valve

Line or auxiliary line fluid is routed through orifice #29 to the dampener bypass clutch valve in preparation for an apply of the torque dampener clutch.


Dampener Clutch Charge

Line or auxiliary line fluid is routed through orifices #42 and #43 into the dampener clutch charge circuit. Dampener clutch charge fluid fills the torque dampener clutch assembly in preparation for an apply of the torque dampener clutch
 

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When the trans is in neutral, it can no longer regen since the link between the wheels and the motors inside the transmission has been disconnected.
This isn't right. There's no mechanical change inside the drive unit when "shifting" into N. It's simply electronic/software.

But, yes, regen is disengaged in N and the Volt defaults to mechanical brakes.
According to the GM service manual operation, all clutches are off in park and in neutral. As far as I can tell, the motors should not rotate from the wheels moving. I may be wrong but that makes sense to me.

[...]
Hmm.... Now I'm not sure.

I know the wheels are always connected to the "planets" in the planetary gear set. But I suppose it's possible that shifting to "N" disengages Clutch 1 (in the diagram below), allowing the ring gear to spin and effectively disconnecting the wheels from MGB. (???)

Does anybody know?

.
 

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This should put you to sleep

Transmission General Description
The 4ET50/4ET55 is a fully automatic, front wheel drive transaxle, variable-speed, electronic-controlled transmission. It consists primarily of a torque dampener assembly, an integral main and auxiliary fluid pump and housing, 1 planetary gear set, 2 friction (rotating) and 1 mechanical (stationary) clutch assemblies, a hydraulic pressurization and control system, and two internal electric motors. Drive motor generator A (1) is 55 kW and drive motor generator B (2) is 111 kW.

The torque dampener contains internal torsional springs, fluid, input shaft and a clutch. The torque dampener acts as a spring coupling to smoothly transmit power from the engine flexplate to the transmission. The dampener provides a mechanical direct drive coupling of the engine to the transmission. The clutch is applied during engine starting and stopping events.

The planetary gear set provides the Electrically Variable forward mode ratios and reverse. Changing ratios is fully automatic and is accomplished through the use of a transmission control module (TCM) located inside the transmission and the drive motor generator power inverter module located under hood. Both the TCM and the drive motor generator power inverter module receives and monitors various electronic sensor inputs and uses this information to vary the torque output at the optimum time based on throttle position.

The TCM commands shift solenoids and variable bleed pressure control solenoids to control torque timing and feel. All the solenoids, including the TCM, are packaged into a self-contained control solenoid valve assembly.

The main hydraulic system primarily consists of a gerotor-type pump, control valve body assemblies, dampener housing and case. The pump maintains the working pressures needed to stroke the clutch pistons that apply or release the friction components. These friction components, when applied or released, support the automatic ratios qualities of the transmission.

The hydraulic system also uses a secondary system and consists of an auxiliary pump located inside of the transmission. This is a gerotor-type pump, electric three phase High Voltage motor, electric harness, and control module. The control module is located inside of the drive motor generator power inverter module under the hood. This pump maintains working pressures when the engine is off.

The friction components used in this transmission consist of 3 multiple disc clutches. The multiple disc clutches combine with a planetary gear set and electric motor to deliver the different ratios, forward and reverse. The gear set then transfers torque through the final drive assembly.

The transmission may be operated in any of the following gear ranges:

P (PARK)
This position locks the wheels and prevents the vehicle from rolling either forward or backward. PARK is the best position to use when starting the vehicle. Because the transmission utilizes a shift lock control system, it is necessary to fully depress the brake pedal before shifting out of PARK. For safety reasons, use the parking brake in addition to the PARK position.

R (REVERSE)
This position allows the vehicle to be operated in a rearward direction. This is done by the Drive Motor with Generator B and is electric.

N (NEUTRAL)
In this position, the propulsion system does not connect with the wheels.

D (DRIVE)
Drive range should be used for all normal driving conditions for maximum efficiency and fuel economy. Drive range allows the transmission to operate in electrically variable modes providing various ratios and output torque.

L (Low)
This position is used for the “feel” of engine braking and can be used for the slowing of the vehicle once the throttle is lifted. While in the position the vehicle will slow quicker and use the drive motor generator B to more aggressively collect energy during a regenerative braking event.
 

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Never felt this before, I'm sure this is absolutely normal.

I was coasting thru a parking lot and had foot on brake lightly when i shifted out of drive into neutral, to backup and grab a parking spot. Doing this caused regen to disengage and the brakes to engage. Its a weird feeling, absolutely normal but you can feel the pads grip the rotor.

Anyone else experience this?

Gen1 Volt. Speed was about 7-10mph range.
Simple answer, don't do that. Don't shift the car into R while driving at highway speeds. Don't push the start button twice while moving. Don't text while driving. And most importantly, don't provoke Elemental or DogMom (or do anything to cause either of them to provoke each other).
 

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This should put you to sleep

Transmission General Description
The 4ET50/4ET55 is a fully automatic, front wheel drive transaxle, ...
The torque dampener contains internal torsional springs, fluid, ...zzzZZZZZ
zzz..snort!... wha?
N (NEUTRAL)
In this position, the propulsion system does not connect with the wheels.
Oh. OK. I get it. Thanks!
 

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The Variable Low 1-2 Reverse Clutch (clutch 1 in the diagram above) must be ON for normal MG2 traction motor operation in Forward or Reverse .This clutch holds the ring gear stationary to create a reaction member.

As mpmoore1979 correctly states all clutches are exhausted with the shift to neutral. (Most notably since there is no traditional manual valve connected to the shifter, PCS3 is electrically turned OFF and the VL1-2R clutch is exhausted into the backfill circuit at the VL1-2R CL Reg valve)

Without this critical clutch that's used MOST* of the time the planetary gear arrangement simply spins on the planetary pinions of the carrier. Without this critical reaction member no mechanical power can be transmitted through the drive unit.
*except in those sneaky "combined" modes where either MG1 or ICE is connected to the ring gear

HTH
WOT


4ET50 transaxle hydraulic circuit diagram
 

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