Machine element or mechanism – Gearing – Interchangeably locked
Patent
1995-03-21
1997-01-14
Herrmann, Allan D.
Machine element or mechanism
Gearing
Interchangeably locked
74359, F16H 308
Patent
active
055928544
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a motor vehicle gearbox comprising two intermediate shafts for transmission of an input torque to an output shaft, whereby a first gear wheel, rotatably mounted on each intermediate shaft and lockable by means of coupling means on respective shafts, is in engagement with a common gear wheel rotatably mounted with respect to the output shaft and lockable for rotation together with the output shaft, said gear wheel being arranged to transmit torque from one intermediate shaft to the other in the disengaged position.
BACKGROUND OF THE INVENTION
Two main types of gearbox of the above mentioned type are known for example from U.S. Pat. Nos. 5,150,628 and 5,388,472. Both these gearbox types are so-called "power shift" gearboxes in which the torque is transmitted alternately via both the intermediate shafts to the output shaft, which means that whilst the torque is being transmitted by one of the intermediate shafts the next gear is preselected on the other intermediate shaft, whereby gear changing itself occurs in that the first intermediate shaft is disengaged and the other is engaged. This can be achieved either by driving the input shaft of each of the intermediate shafts and alternately engaging the input shafts via a pair of clutches outside the gearbox as shown in the aforementioned U.S. Pat. No. 5,388,472, or by driving both intermediate shafts from a common input shaft via friction clutches arranged within the gearbox housing as shown in the aforementioned U.S. Pat. No. 5,150,628.
A characteristic of these known gearboxes is that the torque in a gear stage, namely the lowest gear, is transmitted via both intermediate shafts by means of a common gear wheel. In this way an additional reduction stage is achieved compared with the torque transmission, via only one intermediate shaft at a time, which allows the possibility of higher gearing in the lowest gear than can otherwise be obtained. Alternatively, for a given gearing, larger gear wheels can be used than with torque transmission via an intermediate shaft. The construction gives an extra gear stage without the gearbox needing to be complemented with additional cooperating gear wheels. The result is a very short and compact gearbox with a large number of gears.
OBJECT OF THE INVENTION
The object of the present invention, starting from the gearbox described in the introduction, is to achieve a compact gearbox with many gear stages and with larger span, that is to say larger separation between the lowest and highest gears than can practically be obtained with the described known gearboxes.
SUMMARY OF THE INVENTION
This is achieved according to the invention in that at least a second gear wheel on each intermediate shaft is in engagement with at least a second common gear wheel which is driveably coupled to the first common gear wheel in order to allow torque transmission from said first gear wheel on said first-mentioned intermediate shaft to said second gear wheel on the second intermediate shaft via both the common gear wheels, and in that the second intermediate shaft is divided into two parts rotatable relative to each other, said parts being able to be coupled to each other by coupling means for rotation as a unit.
By creating an additional reduction stage in this way with a second common gear wheel which is smaller than the first common gear wheel, an extremely high gearing can be achieved in the lowest gear. Moreover two additional gears are obtained which, starting from the seven-gear gearbox of the above described known types, give a compact nine-gear gearbox with larger span than can be achieved in these.
BRIEF DESCRIPTION OF THE INVENTION
The invention will now be described in more detail with reference to the embodiments shown in the accompanying drawings wherein FIG. 1 and 2 are two identical figures of a schematically represented gearbox with the torque flow depicted on the different gears.
DETAILED DESCRIPTION OF THE INVENTION
In the figures, numerals 1 and 2 denote two
REFERENCES:
patent: 4269077 (1981-05-01), Vandervoort
patent: 5150628 (1992-09-01), Alfredsson
patent: 5388472 (1995-02-01), Alfredsson
AB Volvo
Herrmann Allan D.
LandOfFree
Motor vehicle gearbox does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Motor vehicle gearbox, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Motor vehicle gearbox will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1381015