Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
2000-12-15
2003-08-12
Bonck, Rodney H. (Department: 3681)
Machine element or mechanism
Gearing
Interchangeably locked
C074S339000
Reexamination Certificate
active
06604438
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an automated drive train for a motor vehicle comprising a single friction clutch, which is actuated by an actuator and is connected at the input side to the motor of the vehicle, and a step transmission connected to the output side of the clutch. The transmission comprises a first plurality of wheel sets for engaging and disengaging corresponding forward gears and a corresponding plurality of positive gear shift clutches, each having synchronization means. The gear shift clutches can be actuated for engaging and disengaging the gears by a second plurality of second actuators. A controller coordinates the control of the first actuator with the second actuators.
The invention further relates to a method for controlling a drive train of a motor vehicle, which comprises a first plurality of wheel sets for engaging and disengaging the corresponding forward gears and a corresponding plurality of positive gear shift clutches, each having synchronization means. The gear shift clutches can be actuated for engaging and disengaging the gears by a second plurality of second actuators. When changing gears, the first actuator is controlled to be coordinated to the second actuators.
2. Description of Related Art
Such an automated drive train and such a method are disclosed in WO93/10378. In transmissions for motor vehicles, particularly passenger vehicles, one distinguishes generally between automatic transmissions and manual transmissions. The former comprise a hydro-dynamic torque converter and a plurality of planet wheel sets, which are controlled by overlapping braking and coupling means, so that no interruption of the driving force occurs when changing gears.
Manual transmissions in contrast are step transmissions with a layshaft arrangement. When changing gears, an interruption of the traction force occurs between the time one gear is disengaged and a new gear is engaged, because the friction clutch associated with the transmission is opened (typically a starting clutch configured to be a dry clutch). Thereby, the motor is completely decoupled from the transmission and therefore also from the vehicle drive wheels.
It is standard in automotive transmissions of today that a locking synchronizer is provided for each positive gear shift clutch for engaging and disengaging gears. A locking synchronizer comprises a synchronizing means (typically a friction coupling) through which a matching of the rotary speed between a wheel set and a shaft (drive shaft) takes place when the friction clutch is open, i.e. not under load. A locking means of the synchronizer prevents or impairs a positive engagement of the gear shift clutch (i.e. the engagement of the gear) until a matched speed is nearly attained.
While the traction force decrease when changing gears by manual shifting is considered to be not particularly unpleasant, the associated “nicking” of the automobile is considered to be less comfortable when the step transmission is automated. In automated step transmissions, the actuation of the friction clutch and gear shift clutches is undertaken by a controller which coordinates actuators, instead of being done by the hand and foot. The traction force interruption is found to be uncomfortable, because with an automated step transmission, the driver is not occupied during gear changing.
Various attempts have been made to mitigate this problem. In the step transmission known from WO93/10378, an attempt is made to shorten the duration of the traction force decrease interruption. This is achieved by two measures. In the transmission disclosed there, two gears, not in sequence with one another, are arranged in one shifting group. In addition, the locking synchronizers of more than one group are activated simultaneously when changing gears. In other words, when disengaging the previous gear (old gear), the synchronization to the rotary speed of the following gear takes place not only with the associated locking synchronizer, but in addition with the locking synchronizer of an additional gear. The times associated with shifting are to be reduced, which achieves shorter shifting times. The duration of traction force decrease is therefore reduced.
A further principle to reduce the traction force decrease is disclosed in the German patent application DE 44 01 812. Instead of a single friction clutch at the input side, a double clutch system is provided. One clutch of the double clutch system associated with the transmission input shaft is for the gear ratios one to five, while the second clutch is associated with the highest gear, namely the sixth gear. During shifting in the lower gears, where the first clutch is first completely opened in known manner and then closed after the shifting, the second clutch, normally open, is closed for a short period, so that the torque of the sixth gear is supplied to the drive shaft of the transmission for a short time. However, when shifting in the lower gears, a considerable traction force decrease still occurs because the torque of the sixth gear is considerably less than that of the lower gears.
The German patent application DE 29 24 656 discloses a further shift transmission in which a single friction disconnection clutch is provided at the input side and in which the wheel set for the second gear does not have the conventional gear shift clutch, but has a wet multi-disc friction clutch. Furthermore, the idler of the first gear is mounted freely on the corresponding shaft. Thus when changing from the first to the second gear, the torque of the motor at the input side of the transmission can be applied to the second gear without opening the friction disconnection clutch and without decrease of the traction force. The change in higher gears however takes place with traction force decrease since for these changes the input side disconnection clutch must be opened.
An automated change speed transmission is disclosed in the German patent application DE 197 35 759. The gear shift clutches for engaging and disengaging the gears are configured as pure positive clutches in the form of claw or draw key couplings. Shifting takes place in that the relative angular position of the elements to be connected is monitored and a signal is output in the ready condition. One gear shift clutch is then opened by a highly dynamic hydraulic system and a new gear shift clutch is closed. When actuating the gear shift clutches, an input side friction disconnection clutch is held in slip condition.
In addition, an automated step transmission with traction force support is disclosed in the German patent DE 195 48 622.
Finally, the so-called “genuine” double clutch transmissions are known, for example from the German patent DE 38 12 327. Two parallel friction clutches are provided on the input side of the transmission. The two clutches are associated with two parallel branches of the transmission, where the parallel interconnection is achieved with a hollow shaft construction. The gears are alternately located on one and then the other drive branch, so that in overlapping operation, the motor torque at the input side can transfer from one branch to the other branch without any traction force decrease.
The mentioned WO93/10378 suffers from the drawback that the central clutch is opened when changing gears so that an uncomfortable decrease in the traction force takes place when shifting, although the interruption time can be optimized. In the transmission of DE 44 01 812, the construction is comparatively complicated due to the double clutch arrangement at the input side. Further, the traction force support can only maximally transmit the torque of the sixth gear to the drive wheels. The complexity of DE 29 24 656 is also considerable, in particular due to the free wheel for the first gear. The concept of DE 197 35 759 cannot completely avoid traction force interruption and requires a very stable construction. The true double clutch transmission, as disclosed in DE 38 123 27 requires not only constructive compl
Harst Richard
Rühle Günter
Seufert Martin
Bonck Rodney H.
Getrag Getroebe-und Zahnradfabrik Herman Hagenmeyer GmbH & Cie.
Le David D.
Shook, Hardy & Bacon L.P.
LandOfFree
Automated drive train for a motor vehicle and method of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Automated drive train for a motor vehicle and method of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Automated drive train for a motor vehicle and method of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3104905