The present invention relates to a vehicle transmission having seven forward gears and one reverse gear, the first forward gear being a crawling gear.
Modern manual shift transmissions for vehicles often exhibit six forward gears and a reverse gear. The first forward gear is usually designed to be relatively short. That is, it exhibits a large transmission ratio. The first gear has to be designed in such a manner that it is possible to accelerate with a full load from a full stop under all customary driving conditions, in particular on steep slopes. Therefore, the maximum speed that can be reached in first gear is relatively low. Consequently one has to shift relatively early into second gear. In most vehicles with manual shift transmissions, one has to shift into third gear already at a speed of less than 100 km/h. From the viewpoint of minimizing consumption, a longer first gear and in the maximum speed range at least one overdrive gear may be preferred.
A longer “normal starting gear” may be advantageous from a consumption viewpoint. However, a long first gear presents a problem when accelerating under full load from a complete stop, for example, on a hill.
The embodiments of the invention provide a transmission that enables a reliable start in all customary driving situations and that offers consumption-related advantages over conventional transmissions. In addition, the transmission exhibits a very compact construction.
According to exemplary embodiments of the invention, the vehicle's “normal driving mode” may be represented by six “normal” forward gears. The term “normal driving mode” is defined here as comprising all driving conditions, in particular all start conditions, except for starting on steep slopes and/or on slopes when the vehicle is heavily loaded. For relatively rare driving situations, where acceleration from a full stop occurs on a hill having a steep slope or on a slope when the vehicle is heavily loaded, a crawling and/or hill gear is provided, which may, for example, use a very short gear ratio.
The exemplary embodiments of the invention are used to integrate a crawling and/or hill gear into a conventional six gear shift transmission without increasing the structural dimensions of the transmission, in particular without having to have an additional gear set plane. An exemplary transmission, according to the invention, may include an input shaft as well as an output shaft, arranged coaxially to the input shaft, and an auxiliary shaft, which is arranged parallel to the input shaft and to the output shaft. In conformity with the six gear manual shift transmission that is currently being manufactured, for example by BMW AG, of Munich, Germany, the transmission includes seven gear set planes. Each of the gear set planes is formed by a gearwheel stage, which includes a first gearwheel and a second gearwheel that meshes with the first gearwheel. Each gearwheel stage includes a gearwheel, which is connected in a rotationally fixed manner to its assigned shaft, and a gearwheel, which is rotationally mounted on its assigned shaft and is rotationally coupled to the assigned shaft by using an assigned shifting element.
According to the invention, one of the exemplary gearwheel stages is “used twice.” The term “dual use” is defined to mean that in a forward gear, intended for normal driving, the torque is transmitted from the first gearwheel of the exemplary gearwheel stage to the second gearwheel of the gearwheel stage. When the crawling and/or hill gear is engaged, the torque is transmitted in the opposite direction, i.e., from the “second gearwheel” to the “first gearwheel.” Thus, according to the invention, it is possible to expand a conventional six gear shift transmission to include a crawling and/or hill gear without having to have an additional gear set plane.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.
Exemplary embodiments of the invention are explained in detail below in conjunction with the drawings.
FIGS. 3 to 10 depict the individual gear stages of the transmission shown in
In the “countershaft concept”, the shiftable gearwheel stages 3 to 8 are arranged, when seen in the direction of the force flow, behind the countershaft constant. The input speed of the input shaft 1 is reduced by the countershaft constant 2, a state that results in relatively large torques being transmitted by way of the shiftable gearwheel stages 3 to 8.
From a functional viewpoint, one difference between the exemplary transmission 14, depicted in
As an alternative, it is envisioned to provide gears 1 to 6 in a manner analogous to a 6 gear transmission, and the 0th gear as the “crawler gear” for all terrain vehicles, providing the greatest torque to the wheels.
The structural design of the exemplary transmission 14 is explained in detail below. The crankshaft 15 of a vehicle engine (not illustrated in detail here) drives a transmission input shaft 17 via a starting clutch 16. The transmission input shaft 17 can be rotationally coupled to an output shaft 19 via a direct shifting element 18, which can be, for example, a sliding sleeve. When the sliding sleeve 18 is closed, the drive shaft 17 and the output shaft 19 rotate at one and the same speed. In parallel to the two coaxially arranged shafts 17, 19 there is a countershaft 20.
According to an exemplary embodiment of the transmission, shown in
The first gear set plane is formed by a gearwheel 28, which is connected in a rotationally fixed manner to the transmission input shaft 17, and a gearwheel 29, which is rotationally mounted on the countershaft 20. The second gear set plane is formed by a gearwheel 30, which is mounted in a rotationally fixed manner on the transmission input shaft 17, and a gearwheel 31, which is rotationally mounted on the countershaft 20. The gear set plane 23 is formed by a gearwheel 32, which is connected in a rotationally fixed manner to the transmission input shaft 17, and a gearwheel 33, which is rotationally mounted on the countershaft 20. Correspondingly the gear set planes 24, 25 are formed by a gearwheel 34 and/or 36, which is mounted in a rotationally fixed manner on the transmission input shaft 17, and an assigned gearwheel 35-37, which is rotationally mounted on the countershaft 20.
The exemplary gearwheel stages 26, 27 are formed by a gearwheel 38 and/or 40, which is rotationally mounted on the output shaft 19, and a gearwheel 39 and/or 41, which is connected in a rotationally fixed manner to the countershaft. The gearwheels 29, 30, 33, 35 and 37 can be rotationally coupled to the countershaft 20 by using assigned sliding sleeves 42-46. The gearwheels 38 and 40 can be rotationally coupled with the output shaft 19 by using assigned sliding sleeves 47 and/or 48.
The torque flow in the individual gears for an exemplary embodiment of the invention is explained in conjunction with the
If one shifts from the crawling and/or hill gear into the normal start gear, i.e., into first gear, leaving the shift position “0” causes the shifting element 43 to disengage first.
Then by passing over the neutral position, the shifting element 47 is disengaged; and the shifting element 48 is engaged. If now the first gear is selected, the shifting element 43 is re-engaged so that the result is the force flow, shown in
In the transition from first to second gear, the sliding sleeve 43/44 is shifted. In second gear the torque is transmitted from the transmission input shaft 17 over the gear set plane 23 to the countershaft 20 and from there over the gear set plane 27 to the output shaft 19.
In third gear the torque is transmitted from the transmission input shaft 17 over the gear set plane 25 to the countershaft 20 and from there over the gear set plane 27 to the output shaft 19.
The fourth gear is a “direct drive.” In fourth gear the torque is transmitted from the transmission input shaft 17 over the direct drive shifting element 18 directly to the output shaft 19.
The allocation of the gears 4 and 5 can also be reversed. That is, the fifth gear can be a direct drive.
In fifth gear the torque is transmitted from the transmission input shaft 17 over the gear set plane 24 to the countershaft 20 and from there over the gear set plane 27 to the output shaft 19.
In sixth gear the torque is transmitted from the transmission input shaft 17 over a sliding sleeve 49 to the gearwheel 38 of the gear set plane 26. The torque, which is transmitted to the countershaft 20 via the gear set plane 26, is passed on to the output shaft 19 via the gear set planes 27.
For the sake of completeness,
If one compares the torque flow in the 0th gear (
In order to actuate the shifting elements and/or the sliding sleeves according to embodiments of the invention, that are shown in
As
The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.
Number | Date | Country | Kind |
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10 2005 021 674.9 | May 2005 | DE | national |
This application is a continuation of PCT International Application No. PCT/EP2006/003069, filed Apr. 5, 2006, which claims priority under 35 U.S.C. §119 to German Patent Application No. 10 2005 021 674.9 filed May 11, 2005, the entire disclosures of which are herein expressly incorporated by reference.
Number | Date | Country | |
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Parent | PCT/EP06/03069 | Apr 2006 | US |
Child | 11937895 | Nov 2007 | US |