The invention relates to a device for shifting changes in the transmission ratio in transmissions of motor vehicles, especially according to the preamble of claim 1.
To control the changes in transmission ratios in motor vehicle transmissions, especially in automatic transmissions, it is necessary to sense and electronically process the positions of the individual shifting elements, for example a selector shaft and/or selector rods or rails.
DE 199 08 036 A1 for example discloses installing on a rotatable and axially movable selector shaft several magnets which with two stationary, electrical coils as sensors generate the corresponding position signals of the selector shaft. In the device according to DE 197 48 115 C2, on the selector shaft there is a ring element which is magnetized on its outer periphery and which interacts with Hall sensors which are located radially on its periphery. In both instances the production effort is increased by the attachment of the magnets and additional installation space is required.
The object of the invention is to propose a device of the generic type which is simpler to produce and more advantageous with respect to the required installation space.
This object is achieved according to the invention with the characterizing features of claim 1. Advantageous developments of the invention can be taken from the other patent claims.
It is suggested according to the invention that at least one magnet is formed directly by a magnetized region on the shifting element. In this way separate magnets and their installation on the shifting elements can be eliminated, additionally installation space being saved by their integration into the shifting element.
Here it is functionally advantageous if the shifting element in the magnetized region is made such that a magnetic field similar to one or more magnets is produced. Thus one or more position signals can be reliably generated.
The cross section of the shifting element in the magnetized region can be made essentially square.
Furthermore, the rod-shaped shifting element can be made tapered at least in the magnetized region, so that the sensor, for example a Hall sensor or a small coil, can lie within the peripheral region of the other shifting element to the advantage of the installation space.
The tapering can be produced preferably according to structural circumstances by unilateral or bilateral recesses on the shifting element.
Alternatively, at least in the magnetized region of the shifting element a slot-like recess can be provided therein, by means of which a preferred cross section of the magnetized region or regions of the shifting element can be easily ensured.
Thus, of the legs of the shifting element which are formed on either side of the recess, one leg can be magnetized to which the stationary sensor is adjacent, or the legs of the shifting element which are formed on either side of the recess can be magnetized, then the stationary sensor being able to project into the recess in a structurally especially favorable manner.
In terms of production technology, the shifting element can be made especially easily as an axially movable selector rail with an essentially rectangular cross section. In this connection, to further reduce the production cost, the recesses and/or tapers provided at least in the magnetized region on the selector rail can be produced by punching.
Several embodiments of the invention will be detailed below. The figures are schematic.
The actuator 16 is triggered in the conventional manner via an electronic automatic transmission control which is also connected to one or more stationary sensors 18 for position detection of the selector rail 10. The sensors 18 are Hall sensors or small coils of known design which in interaction with one or more magnetic fields on the selector rail 10 generate position signals which are evaluated accordingly in the electronic automatic transmission control device which is not shown.
The selector rail 10 is made rectangular in cross section and in the region of the position sensor 18 is provided with a tapered section 10a such that this section 10a has a more or less square cross section (compare
In the region of the sensor 18 which, as is to be seen, projects into the peripheral region of the selector rail 10 tightly against the tapered section 10a, a magnetized region 10b (shown cross-hatched) is formed which produces a magnetic field similar to a permanent magnet for triggering the sensor 18. Thus the Hall sensor 18 in the position of the selector rail 10 shown in
Instead of a tapered section 10a, the selector rail 10′ is provided with a slot-shaped recess 10c which lies outside the center axis of the selector rail 10′. On the lower leg 10d of the selector rail 10′, which leg borders the recess 10c and which in turn is chosen to be more or less square in cross section (cf.
The selector rail 10″ has a slot-like recess 10c which lies symmetrically in the center axis of the selector rail 10″ and into which the stationary sensor 18 projects laterally in a divergent arrangement (cf.
The legs 10d and 10e which border the recess 10c and which are made with the same thickness and more or less square in cross section are provided with one magnetized region 10b each, which lie axially offset to one another and which both interact with the sensor 18 and generate a position signal for the respective overlapping with the sensor 18.
The described steel selector rails 10 can be produced in a punching process, also the tapered section 10a or the recesses 10c being punched accordingly at the same time.
The invention is not limited to the illustrated embodiment. Instead of a selector rail 10 as the shifting element, an axially movable selector rod and/or a selector shaft which can move translationally and rotationally (for example for gear selection and gear shifting) can also be used as the shifting element of a transmission.
Number | Date | Country | Kind |
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10 2004 060 771.0 | Dec 2004 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP05/13161 | 12/8/2005 | WO | 6/18/2007 |