SAE conference papers released this week

I'm digesting some of the SAE hybrid conference papers I bought on Sunday:

SAE 2009-01-1332 - "Development of New Hybrid System for Compact Class Vehicles"

This is the general systems approach to the new ZVH30 (2010) Prius. It is a recommended first read since it covers all systems.

SAE 2009-01-1048 - "Newly Developed Inline 4 AR Series SI Engine"

Here we get the details of the internal mechanics. One surprise, it uses variable oil pump to reduce internal losses.

NOTE: this is the Camry engine, not the 1.8L ZVH30 engine. Although not the same model, it introduces another energy saving device, a variable oil pump.

SAE 2009-01-0726 - "Development of New Hybrid Transmission for Compact-Class Vehicles"

It took me nearly a year and looking at Graham mini-scanner data to finally stop getting a headache. Time to bulk up on aspirin again. <GRINS>

SAE 2009-01-1322 - "Vehicle Inertia Impact on Fuel Consumption of Conventional and Hybrid Electric Vehicles Using Acceleration and Coast Driving Strategy"

I'm not a fan of "pulse and glide" and this paper requires close reading. A vehicle model was used along with some benchmarking so I'll be looking closely at the model and results. Looking at Table 4, "30-40 mph, 20 seconds of acceleration" shows their field test had a 25% performance improvement over the equivalent steady state, 35 mph cruise speed. My field testing of 25-40 mph, 33 mph cruise speed showed only an 11% improvement. We're off by a factor of two so the I'll be looking closely at their protocol.

SAE 2009-01-1321 - "An Analytic Foundataion for the Two-Mode Hybrid-Electric Powertrain with a Comparison to the Single-Mode Toyota Prius THS-II Powertrain"

Sad to say, this is an analysis of the soon to be replaced transaxle. Still, a quick scan suggests there may be some analytic techniques that may help us understand the ZVH30.

NOTE: This report is flawed because the author didn't realize MG1 is rated at 24 kW yet his model claims a loss of 15.6 kW at 80 mph. There is no way with any reasonable efficiency numbers that the MG1-to-MG2 power loss could exceed 3 kW. I'm also concerned about his use of "42 mph" as "its mechanical point," which is used in other parts of the same paper as a transition between a forward or reverse power flow.

BTW, I would recommend advocates of other hybrids and vehicle technologies search the SAE web page for recently released papers. NOTE: there are some security features implemented to limit making multiple paper copies of these papers. The papers cost $15/each for non-members and with the security features ... well shop wisely. I spent $75 on my set but then papers are a way to save 'lab time.'

Bob Wilson