Prime TMS (thermal management system)

no, so i have to think no change. when you think about it, not much difference other than higher ev speed and no ice when you punch it. not sure how much heat that will create.

 

thanks mark, i'll try to remember this when i run across the post saying there might not be any forced cooling at all.

 

I would still consider fan-driven air cooling to be "active cooling" as opposed to something like the Nissan LEAF which was completely passive with no fan.

 

What did you find out about any new changes in the transaxle vs the regular gen 4?

We know there is a new one-way clutch. Where is it physically located? Is it inside the transaxle on the planetary carrier or is it external to the transaxle and on the output axle of the engine maybe as part of the clutch/damper between the engine and the engine input to the transaxle?

Did they add any other clutching mechanism beyond that? Danny mentioned something about a clutch and high rpm inertia and MG2 freewheeling but later deleted it from his "insider notes" thread. Do you know what that was about?

Any other changes to gear ratios or motor windings (kW or torque ratings) between gen 4 and the Prime's gen 4 transaxle? In particular, I'm wondering if it is really just exactly the same P610 gen 4 transaxle but with a one-way clutch located just exterior to the transaxle case. Any idea?

 

Okay.

I think you mean MG2 (the bigger motor).

 

Yes, I saw that earlier. It's interesting and some of it sounds credible like the strengthening of some internal transaxle components. Other parts I'm less sure of. He talks about 95 kW of motor output but that's kind of irrelevant for EV driving if you have less battery output than that. Autoblog claims the max battery output in the Prime is 68 kW versus 37 kW for the old PHEV. This article says the old PHEV motor output was 68 kW but I thought the old MGB was 60 kW.

 

i wonder if prime is going to be faster than regular prius in hybrid mode... there is potential for 180 hp there.

 

We do. The specs are listed as being the same as the regular gen 4 -- 53 kW and 163 Nm.

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The overall maximum system output is listed as being the same 90 kW or 122 HP as the regular gen 4. This is because MG2 is already being fed power from MG1 which is generated from part of the gas engine output and that only leaves a limited additional power capability in MG2 that can be filled from the battery. That spare MG2 capacity is small enough (less than 30 kW) so that it can be fully provided by the regular gen 4 hybrid battery.

Even though Prime can reportedly output up to 68 kW from its battery, MG2 has already maxed out under hard acceleration with the gas engine so both the regular gen 4 and the Prime put out the same power. Since the Prime is about 300 pounds heavier, it may actually be slower to accelerate 0-60 than the regular gen 4.

In contrast, the gen 2 Volt's MG2 equivalent is 280 Nm and 87 kW (vs Prius 163 Nm and 53 kW) but with similar gas engine output so the Volt has substantially more excess capacity in its motor to absorb additional power from the battery pack to assist the gas engine during hard acceleration. The Volt's overall rated powertrain output is 111 kW or 149 HP.

 

Having the one-way clutch allows them to combine the motor power and inverters for MG1 and MG2 together rather than having to have an oversized MG2 motor and inverter that is used by itself for EV driving.

The two motors combined reportedly are capable of outputting up to 95 kW but the battery itself can reportedly only output up to 68 kW so EV-only driving is limited to that.

The combined gas engine plus motors and battery pack can output up to 90 kW or 122 HP so it makes sense for "EV auto" mode to fire up the gas engine under hard acceleration.

The gen 2 Volt has a bigger battery pack that can output up to 120 kW which is just a little more than its two motors combined are rated for (111 kW) so gas engine vs EV-only acceleration are about the same in the Volt.

 

Correct me if I'm wrong, but in the gen 1 PiP, MG2 provides both motive power and regen when braking. MG1 starts the ICE and provides regen from the ICE to sustain battery charge. Does the second gen operate in the same way?