Chrysler Dual-Clutch Transmissions: Automated Manuals - 79REM and 62TEM
Chrysler’s automatically operated manual transmission (“dual-clutch automatic”), was engineered for trucks and cars. This type of transmission has never successfully been applied to light-duty vehicles, and never with the degree of sophistication and cleverness being applied by Chrysler engineers.
However, it now appears that, as part of Cerberus’ attempt to swap Chrysler for GMAC, the transmissions will not be made for Chrysler; the contract with Getrag to produce them has been broken. (10/20/2008).
This transmission, whose development started around 1998, was briefly confirmed for production, starting around mid-2009. The company wrote:
The new dual-clutch transmission will debut in international markets on the all-new 2009 Dodge Journey, the 2009 Dodge Avenger and the 2009 Chrysler Sebring. It will be mated to a 2.0-liter turbo diesel engine. (It is available on these cars.)
The dual-clutch transmission is an automatic transmission which uses a manual transmission style lay-shaft gear arrangement. One clutch drives the odd numbered gears and reverse, while the other clutch drives the even numbered gears. During shifts, the next gear is anticipated and pre-selected. Then one clutch is opened while the other is closed, allowing shifting without torque interruption. The result is quicker acceleration and refined shift quality. Further, with the lay-shaft arrangement of gears, there is increased flexibility to optimize gear ratio selection for performance and fuel economy.
The dual-clutch transmission does not require a torque converter to transfer engine torque to the transmission. Instead, it uses two wet multi-plate clutches. With the wet multi-plate clutch system, the clutch components are bathed in lubricating/cooling fluid in order to provide adequate thermal capacity.
The wet multi-plate clutch system uses hydraulic pressure to actuate the clutches and provide for gear selection. With this system, the power flow from the engine to the transmission is not interrupted during a shift, resulting in a power-on shift. This means that there is less torque disturbance than a conventional planetary automatic transmission with torque converter. Also, by eliminating the torque converter and reducing the number of shift clutches, parasitic losses are reduced leading to improved fuel economy.
The automated manual (dual-clutch) transmission – developed in partnership with Getrag [based on many Chrysler patents] – will be used in significant volumes in 2010 model-year vehicles. The transmission is expected to deliver a fuel economy improvement of up to 6%.
Production is currently set at 700,000 units per year, according to Frank Klegon, as quoted in Automotive News (July 2, 2007). That would be enough for every nearly Dodge made for six months, or about one quarter of Chrysler's vehicles.
Unlike Toyota's sequential automatic and most other clutchless models, it had systems to avoid slipping at traffic lights (on hills), to make getting into gear very, very fast, and to make extremely fast, smooth shifts. Unconfirmed reports said it was set to go into Rams when Stuttgart objected to the cost and temporarily ended the project. The transmission will be made in a joint venture with Chrysler's traditional German partner, Getrag, to reduce up-front production costs and to make use of Getrag’s dual-clutch patents.
This is a very exciting system - think of cutting 1-2 seconds off each car's 0-60 times while raising gas mileage, and making the car more pleasant to drive.
Large parts of the dual-clutch system (as it will be referred to in most reports) were used by the Chrysler ME-412, and may show up in Mercedes supercars as well. It may also be shared with other manufacturers, including Volkswagen.
The 62TEM (front-wheel drive transverse electromechanical transmission) will reportedly have one overdrive with 500 Nm (370 pound-feet) maximum input torque, 10,000 lbs GVW, 210,000 miles durability, using an integrated final drive and differential.
The dual-clutch will be a major advantage for Dodge trucks and minivans, especially given that many see the Chrysler automatics as being “a reason not to buy;” some speculate that the Cummins turbodiesels are being held back in power to avoid transmission damage, costly to Dodge’s image during a truck power war. At the moment, it appears that Chrysler is giving preference to front wheel drive vehicles, and is building the 62TEM first. The 79REM, for trucks, has been developed, but may be released after the 62TEM; no announcements have been made but this does not mean that the company is not working on it.
Automatically shifted manual transmission: some Chrysler dual-clutch automatic patents
A June 4, 2000 patent with inventor Donald L. Carriere was granted for "an electro-mechanical automatic transmission having... a first input shaft and a second input shaft concentric with the first input shaft....with a pair of electro-mechanical clutch actuators for selectively disengaging dual clutches... as well as an electro-mechanical shift actuator system which operatively engage the synchronizer devices for selectively engaging the drive gears. ... The dual clutch system of the present invention includes two dry discs driven by a common flywheel assembly. Two electro-mechanical clutch actuators are provided to control disengagement of the two-clutch discs independently. Shifts are accomplished by engaging the desired gear prior to a shift event and subsequently engaging the corresponding clutch. ...The transmission of the present invention can be in two different gear ratios at once, but only one clutch will be engaged and transmitting power. To shift to the new gear ratio, the driving clutch will be released and the released clutch will be engaged. The two-clutch actuators perform a quick and smooth shift as directed by an on-board vehicle control system using closed-loop control reading engine RPMs or torque. The transmission shaft that is disengaged will then be shifted into the next gear ratio in anticipation of the next shift." Clever!
We'll also note that a May 18 patent from Jeffrey P. Cherry is for an "electro-mechanical clutch actuator system ... for a transmission having dual input shafts with respective clutches."
Patent 6,491,147 describes a way to more easily add a clutch pedal to a car with an automatic. Why? We don't know. Maybe one of the patent engineers was feeling frisky. We certainly would prefer the option to drive a stick-shift.
October 15, 2002: control of a dual clutch (manual) transmission, where the first clutch acts to transmit torque to the first driven gear, and the second clutch transmits torque to the second driven gear. Richard G. Reed, Jr.; Jeffrey P. Cherry. The goal is to make a far smoother manual transmission, while increasing efficiency and power transmission, without excessive heat buildup. But could this also be a step in creating an automatically operated manual transmission. Reed was responsible for other patents, including 1998’s filing #6,012,561 covering “dual clutch design for an electro-mechanical automatic transmission having a dual input shaft.”
Patent 6,490,517 (Phillip McGrath and Yi Cheng) gets to the more mundane question of being in the correct gear: "a method for determining a maximum performance gear for an automobile when performing acceleration / deceleration maneuvers and a system for enhancing a motor vehicle's gear indicator capabilities." The target is a manual transmission but the technology could be used in an automatic.
Martin S. Burkle’s 2006 resume (thanks, “redhed”) shows that he worked for noted transmission maker ZF before coming to DaimlerChrysler in 2001 as a project engineer (working out of Auburn Hills). More to the point, he provides some details on the two versions of this transmission — which explains rumors of a minivan propelled by an automated manual transmission:
Designed and engineered the 79REM (rear-wheel drive electromechanical transmission) seven speed, with two overdrive for 850 Nm diesel input torque, 26,000 lbs GVW with 120 mm centerdistance and 300,000 miles durability, input constant design. ... Designed and engineered the 62TEM (front-wheel drive transverse electromechanical transmission) six speed, with one overdrive for 500 Nm diesel input torque, 10,000 lbs GVW with 95 mm centerdistance and 210,000 miles durability, integrated final drive and differential.