[001] DETERMINATION OF THE ROTATIONAL SPEED
OF A TRANSMISSION SHAFT
[002]
[003]
[004] The invention relates to an arrangement for determining the rotational
speed of a transmission shaft. The arrangement includes a transmission shaft, a rotational speed transmitter that is rotationally fixed to the transmission shaft and a stationary rotational speed sensor, such that the rotational speed can be detected from the rotational speed transmitter. Furthermore, the present invention relates to a transmission with such an arrangement and a method for determining the rotational speed of a transmission shaft.
[005]
[006] Various arrangements fordetermining the rotational speed of a transmission
shaft are known from the state of the art. Also known as rotational speed detection devices, these arrangements for generating a speed signal for a motor vehicle or

fixed to the corresponding transmission shaft. A stationary rotational speed sensor is associated with the rotational speed transmitter in order to detect the rotational speed of the rotational speed transmitter.
[007] In general, this is the way in which DE 198 14 758 A1 describes a device
for detecting the rotational speed of a shaft. The known device features a signal transmitter that is rotationally fixed to the shaft. The signal transmitter is configured like a gear wheel, where the teeth of the gear wheel each feature a steep and a flat tooth flank. In addition, an analog Hall effect sensor is provided that detects the rotational speed In a radial direction on the periphery of the gear wheel, i.e., on the teeth. Thanks to the different angles of the two flanks of each tooth, it is possible to determine the rotational speed and the direction of rotation of the shaft with only one sensor and at a constantly updating rate, even when the shaft is rotating at a very low rotational speed.
[008] DE 103 47 494 A1 describes a similar arrangement that is supposed to
determine the torque of transmission shafts. For this purpose, the known device

is comprised of a transmission shaft on which a rotationai speed transmitter gear wheel is rotationally fixed, where a stationary rotationa! speed sensor is once again associated with the rotational speed transmitter gear wheel. The teeth of the rotational speed transmitter gear wheel, as they rotate past the rotational speed sensor, produce electric impulses, which are fed to a corresponding evaluation unit.
[009] The state of the art shown above has proved its value in practice, but the
additional signal transmitter, rotational speed transmitter or rotational speed transmitter gear wheels result in an increase in the total length of the transmission and to an increase in weight, which can be a disadvantage with certain arrangements of the transmission inside the motor vehicle.
[010] !n comparison, DE 102 23 625 A1 proposes a rotationai speed detection
device for a transmission of a motor vehicle that likewise comprises a signal transmitter and a sensor, where the signal transmitter is integrated in a dust-proof cover for an output-side, shaft-sealing ring. The dust-proof cover is arranged outside the transmission housing and is connected in a rotationally fixed manner to the housing. This solution is an advantage in so far as the existing dust-proof cover functions at the same time as a signal transmitter, which means that the

Nevertheless, the externally situated sensor leads to an enlargement of the
transmission, which makes installation in a motor vehicle more difficult.
Furthermore, it is necessary to accordingly modify the cover to protect against dust
so that it can function as a signal transmitter. It is proposed that equidistant size
increases be provided on the periphery of the dust cover which, not only further
increase the size of the transmission, but which also result in greater fabrication
expense.
[Oil] It is the object of the invention to devise an arrangement for detecting the
rotational speed of a transmission shaft that overcomes the disadvantages cited above. Furthermore, it is an object of the invention to devise a transmission for a motor vehicle with such an advantageous arrangement and, in addition to that, it is the object of the invention to disclose an improved method of detecting the rotationai speed of a transmission shaft.

[012] This object is achieved by means of the characteristics specified in patent
claim 1, 15, or 17, Advantageous embodiments of the invention are the subject of the sub-claims.
[013]
[0141 According to the invention, the arrangement for detecting the rotational
speed of a transmission shaft features a transmission shaft. This can be the input shaft, a countershaft, the main shaft or the output shaft of a transmission, for example. A rotational speed transmitter is rotatlonally fixed to the transmission shaft. Furthermore, a stationary rotational speed sensor is provided by which means the rotational speed at the rotational speed transmitter can be detected. The rotational speed transmitter is provided on the periphery of the shift collar, which can also involve integration of the rotational speed transmitter to the shift collar. The shift collar is arranged in an axially movable and rotationally fixed manner on the transmission shaft and is part of a coupling device. The coupling device could be a claw coupling which, among other things, encompasses the cited shift collar. In addition, the coupling device can also contain a synchronization device. The coupling device can serve to couple the transmission Shaft to a tree wheel on the transmission shaft or to another transmission shaft.
[015] The rotational speed transmitter is therefore based on the existing shift
collar of the coupling device, such that--in a manner similar to that of the rotational speed detection device known from DE 102 23 625 A1--an existing transmission component functions partially as a rotational speed transmitter. In this respect, a complete rotational speed transmitter gear wheel is not necessary so that a reduction in weight is achieved as well as a reduction in the length of the transmission. Compared to the state of the art according to DE 102 23 625 A1, the advantage is also achieved that the space in the interior of the transmission can be used that would be available in any case in the area of the periphery of the switching for the arrangement of the rotational speed sensor. In that way, the transmission is not enlarged as it is when the sensor for the dust-proof cover is arranged on the outside of the transmission housing. In addition, in the case of a transmission with the inventive arrangement, a dust-proof cover for the

- shaft-sealing ring can be dispensed with, particularly as this is not needed for determining the rotational speed of the transmission shaft.
[016] In a preferred embodiment of the inventive arrangement, the rotational
speed sensor is aligned in such a way that the rotational speed can be determined in the radial direction on the rotational speed transmitter on the periphery of the shift collar. The rotational speed sensor can be a Hall effect sensor or an induction sensor. Detection in a radial direction, which can be achieved through a lateral, radia! arrangement of the rotational speed sensor, is more reasonable than the shift collar being displaceable in an axial direction, which would lead, with detection in an axial direction, to a collision of the shift collar with the rotational speed sensor.
[017] in a particulady preferred embodiment of the inventive arrangement,
the shift collar features external teeth that can be made to mesh with internal teeth of a transmission part that is to be coupled. The transmission component to be coupled can be a free wheel on the transmission shaft or another transmission shaft. The rotational speed transmitter in this embodiment is formed by the external teeth of the shift collar. In this way, the external teeth, which are necessary for coupling with another transmission part, can be used in an

shift collar that is necessary in the known dust-proof cover (DE 102 23 625 A1), is not required. Hence the design of the arrangement is simplified and the production expenditure is reduced.
[018] In an additional advantageous embodiment of the inventive arrangement,
the shift collar can be displaced from a neutral position into a first coupling position in which the externa! teeth mesh with the internal teeth of a first transmission part that is to be coupled, such as a first free wheel on the transmission shaft or another transmission shaft.
[019] According to an additional advantageous embodiment of the inventive
arrangement, the shift collar can also be displaced from the neutral position in the opposite direction into a second coupling position in which the external teeth mesh with the inner teeth of a second transmission part that is to be coupled.

The opposite direction is to be understood as the direction opposite to the direction in which the coupiing sleeve is displaced into the first coupling position.
[020] In order to guarantee that the arrangement can permanently determine the
rotational speed of the transmission shaft, the rotational speed transmitter is arranged in such a way in a preferred embodiment of the inventive arrangement that the rotational speed in the neutral position in the first coupling position, and in the second coupling position can be detected from the externa! teeth. The rotational speed sensor can therefore be arranged in such a way that it detects the rotational speed in the neutral position of the shift collar in a middle area of the external teeth, while it detects the rotational speed in the two coupling positions respectively in an outer area of the external teeth in each instance, it is guaranteed that detection from the external teeth can take place in all predetermined positions into which the shift collar is displaced.
[021] In an additional advantageous embodiment of the inventive arrangement,
a shift fork is provided for displacing the shift collar.
[022] When the shift fork is used, in order to guarantee that assured displacement
of the shift collar and permanent detection of the rotational speed will be possible from the external teeth, in a preferred embodiment of the inventive arrangement, a groove is provided in the snin collar win which the sniTt fork is engaged. The external teeth thereby feature two lateral externa! tooth sections between which the peripheral groove extends. The rotational speed can then be detected in the neutral position and in the first coupling position of the shift collar from one of these external teeth sections, while the rotational speed in the second coupiing position of the shift collar can be detected from the other external teeth section. In order to achieve this, the dimensions and arrangements of the rotational speed sensor, the external teeth sections and the peripheral groove must be accordingly matched with each other. Thus the rotational speed cannot be detected when the rotational speed sensor is situated above the pedpheral groove, however, it is guaranteed that in the predefined neutral and coupling positions of the shift collar, the rotational speed can be detected from the respective external teeth sections.

[02-3] In an additional advantageous embodiment of the Inventive arrangement,
the rotational speed sensor is attached to the end of a sensor arm, which extends to the shift collar or the rotational speed transmitter of the shift collar.
[024] !n order to reasonably exploit the space inside a transmission housing,
in an additional advantageous form of the inventive arrangement, the sensor arm is attached in a transmission housing and extends through the actuator space, The actuator space is understood here as the space inside the transmission housing in which the actuating elements of the gearshift assembly are located, such as the rails of a continuously variable transmission.
[025] According to an additional preferred embodiment of the inventive
arrangement, a sensor-side section of the sensor arm, i.e., the section of the sensor arm that receives the rotational speed sensor, is configured in such a way that in the neutral position, the first coupling position and/or the second coupling position, the section extends into or through the shift fori< opening. The shift fork opening is understood here as the opening that remains between the two braces of the shift fork and the encompassed shift collar.
[026] in another preferred embodiment of the inventive arrangement, the section
of the sensor arm section on the sensor side is arranged opposite the shift fork opening and displaced in the direction of the shift fork opening. Lateral displacement is understood as lateral displacement which respect to a section of the sensor arm on the attachment side. In this embodiment, the sensor-side section can plunge into the shift fork opening during displacement of the shift fork, while the shift fork does not collide with the attachment-side section.
[027] In order to also efficiently use the space that is occupied by the sensor arm
inside a transmission housing, in another advantageous embodiment of the inventive arrangement, a free wheel is provided on the transmission shaft such that the free wheel can engage the transmission shaft via the coupling device, where a gearset rotational speed sensor is provided on the sensor arm, by means of which the rotational speed of the free wheel can be detected from the teeth of same. The sensor arm thus serves to accept an additional measuring element for which no additional holder is necessary.

f02-8] in an additional advantageous embodiment of the inventive arrangement,
the transmission part to be coupled is a free wheel on the transmission shaft or a stationary gear wheel on another transmission shaft, fn the latter case, this could be the input shaft of the transmission where the direct gear is en-gaged by way of the clutch.
[029] The inventive transmission for a motor vehicle features the inventive
arrangement for determining the rotational speed of a transmission shaft.
[030] In a preferred embodiment of the inventive transmission, the transmission
shaft is the main shaft of the transmission, v^here an additionai two countershafts are provided, between which the main shaft is mounted in a floating manner.
j0311 The inventive method of determining the rotational speed of a transmission
shaft consists of the methodological steps of providing a transmission with a transmission shaft and a coupling device that features an axially displaceabie shift collar that is connected in a rotationally fixed manner to the transmission shaft and the registration of the rotational speed on the penphery of the shift collar. !n this case, the transmission is preferably a transmission of the previously cited type.
[032]

exemplary embodiment with reference to the accompanying drawings, wherein:
[034] FIG. 1 is a schematic representation of a transmission with the inventive
arrangement for determining the rotational speed of a transmission shaft;
[035j FIG, 2 is a partial lateral view of the arrangement in FIG. 1 with the shift
collar in the neutral position;
[036] FIG. 3 is a view of the arrangement in FIG. 2 in the direction of the arrow A;
[037] FIG. 4 is the arrangement in FIG. 2 with the shift collar in a first coupling
position, and
[038] FIG. 5 is the arrangement in FIGS. 2 and 4 with the shift collar in a second
coupling position.

[0391
[040] FiG, 1 shows a schematic representation of a transmission 1 for a motor
vehicle, where the transmission features an arrangement for determining the rotational speed of a transmission shaft. The transmission 1 is a co-axia! transmission with an input shaft 2, a main shaft 3 and an output shaft 4 that are arranged end to end along on an axis 5. The main shaft 3 is connected via an only schematically implied planetary gearset 6 with the output shaft 4. In addition, two countershafts 7,8 are provided, which extend parallel to the input shaft 2, the main shaft 3 and the output shaft 4 along two axes 9, 10. There is a pinion gear 11,12 affixed to each of the countershafts 7, 8. These gears mesh with an output gear wheel 13 of the drive shaft 2 so that the countershafts 7, 8 can be driven by the drive shaft2. Furthermore, additional fixed gearwheels 14,15 are provided on the countershafts 7, 8. These gear wheels mesh with free wheels 16, 17 on the main shaft 3. The main shaft 3 is mounted in a fioating manner between the two countershafts 7, 8 with sufficient play between the input shaft 2 and the output shaft 4. The transmission 1 also features a transmission housing 18, through which the ends of the input and output shafts 2,4 opposite the main shaft 4 extend outwards.

of the main shaft 3 with one of the free wheels 16, 17, a coupling device 19 is
provided on the main shaft. The coupling device 19 features a shift collar 20 that
can be axially displaced and is arranged in a rotationally fixed manner by way of
a sleeve carrier 21 on the main shaft 3. in the sides of the free wheels 16, 17,
facing the shift collar 20, there are also recesses provided into which the shift
collar 20 can be displaced where, inside the recesses, internal teeth 22, 23 are
provided, whose function will be described below.
[042] The rest of the design of the arrangement will be described below with
reference to FIGS. 2 to 5. FIG. 2 shows a partial lateral view of the arrangement. The shift collar 20 features external teeth 24 that are configured as straight teeth. In addition, an intermediate peripheral groove 25 is provided in the shift collar 20 that divides the external teeth 24 into two lateral external teeth sections 26, 27. In order to axially displace the shift collar 20, a shift fork 28 is provided, which can be

seen in FIG. 3 in a front view, The shift fork 28 consists of two braces 29, 30,
which fateraiiy engage the peripheral groove 25 in the shift collar and are merged
in order to be attached together to a rail 31 of a continuously variable transnnission.
The rail 31 extends parallel to the main shaft 3 through an actuator space 32 inside
the transmission housing 18, which extends above the main shaft 3 and the free
wheels 16, 17. The shift fork 28 is configured to be long enough that a shift fork
opening 33 remains between the braces 29, 30 and the adjacent shift coHar 20,
as can be seen in FIG. 3.
[043] The arrangement also comprises a rotational speed sensor 34 that is
arranged in a stationary manner close to the periphery of the shift collar 20 and the external teeth 24 of the shift collar 20. The rotational speed sensor 34 is attached to the end of a sensor arm 35. The sensor arm 35 comprises an attachment section 36 that is attached to the transmission housing 18 and extends through the actuator space 32. The attachment section 36 extends initially in an essentially radial direction, and then assumes a course that is aligned essentially parallel to the main shaft 3. A sensor-side section 37 is connected to the attachment section 36. The sensor-side section extends, in turn, in a radial direction toward the shift collar 20 and retains the rotational speed sensor 34 at its end. Due to the

which is opposite the shift fork opening 33 (FIG. 3), is deposed, in an offset manner, in the direction of the switch fork opening 33.
[044] On the sensor arm 35, a gearset rotational speed sensor 38 is attached to
the part of the attachment section 36 that is aligned parallel with the main shaft 3, so that to be arranged close to the periphery of the free wheel 16 facing the teeth of the free wheel 16. Using this gearset rotational speed sensor 38, the rotational speed of the freg wheel 16 can also be detected from the teeth of same.
[045] The arrangement also features a rotational speed transmitter that is
arranged on the periphery of the shift collar 20. The rotational speed transmitter is formed by the external teeth 24 facing the rotational speed sensor 34 or by the external teeth sections 26, 27 of the shift collar 20. The rotational speed sensor 34, which in the present example is a Hall effect sensor or an induction sensor, detects the rotational speed in a radial direction from the external teeth 24. This

means that the teeth of the external teeth system 24 that rotate past the rotational speed sensor 34 produce impulses in the rotational speed sensor 34 that are relayed to an evaluation unit that is not shown. The latter can calculate the rotational speed of the main shaft 3 from the number of impulses per unit of time, The registration of the rotational speed in a radiai direction is particularly advantageous in the present transmission 1, because in it, the radial play of the main shaft 3 is smaller than the axial play of same so that the range of tolerance of the rotational speed sensor 34, within which rotational speed determination can be reliably performed, is greater than the radiai play.
[C46] The characteristics of the embodiment of the arrangement and its mode of
operation will be described below with reference to FIGS. 2 to 5
[047] In FiG. 2, the shift collar 20 is in an intermediate neutral position, in which
the externa! teeth 24 of the shift collar 20 do not engage the internal teeth 22, 23 of the adjacent free wheels 16,17, i.e., neither of the free wheels 16,17 is coupled in a rotationally fixed manner with the main shaft 3. The rotational speed sensor 34 can detect the rotational speed of the main shaft 3 from the external teeth section 26, specifically from an area of the external teeth section 26 that is close to the peripheral groove 25. in the neutral position, the sensor-side section 37 of

braces 29. 30. Thanks to the lateral displacement of the sensor-side section 37
relative to the attachment section 36, there is no collision between the shift fork 28
and the sensor arm 25.
[048] The shift collar 20 can now be axially displaced from the neutral position to
a first coupling position, shown in FIG. 4, with the help of the continuously variable transmission and the shift fork 28. In this way, the shift collar 20 enters the lateral recess in the free wheel 17 and meshes with the internal teeth 23 of the free wheel 17. Hence the rotation of the input shaft 2 can be transferred to the main shaft 3 via the countershaft 7, 8, the fixed gearwheels 14, 15, the coupled free wheel 17 and the coupling device 19. In the first coupling position of the shift collar 20, the rotational speed sensor 34 continues to detect the rotational speed from the external teeth section 26, this time, however, in an area of the external teeth section 26 that is arranged at a distance from the peripheral groove 25,

because the shift collar 20 has been displaced into the first coupling position to the right, in the first coupling position, the sensor-side section 37 of the sensor arm 35 no ionger extends into the shift fork opening 33.
[049] In addition, the shift collar 20 can be axially displaced with the help of the
continuously vahabie transmission and the shift fork 28 from the neutral position (FIG. 2) to a second coupling position, which is shown in FIG. 5. In this way, the shift collar 20 enters the lateral recess in the free wheel 16 and engages the internal teeth 22 of the free wheel 16. Hence the rotation of the input shaft 2 can be transferred via the countershafts 7, 8, the fixed gear wheels 14, 15, the engaged free wheel 16 and the coupling device 19 to the main shaft 3. In the second coupling position of the shift collar 20, the rotational speed sensor 34 now detects the rotational speed from the external teeth section 27. because the shift collar 20 is displaced to the left in the second coupling position, !n the second coupling position, the sensor-side section 37 of the sensor arm 35 extends, in turn, through the shift fork opening 33, where It is again thanks to the lateral displacement of the sensor-side section 37 of the sensor arm 35 that no collision occurs between the shift fork 35 and sensor arm 35.
[050] The embodiment of the rotational speed sensor 34, the width of the

are adapted to each other in such a way in the present example that the rotational speed in the neutral position (FIG. 2), the first coupling position (FIG. 4) and the second coupling position (FIG. 5) can always be detected by the rotational speed sensor 34 from the external teeth 24. In this case, it should preferably be ensured that the central axis of the rotational speed sensor 34, which is designated with the reference numeral 38 in the Figures, is aligned in each of the cited position with the external teeth 24.

CLAIMS
1. An arrangement for determining the rotational speed of a transmission
shaft (3) featuring a transmission shaft (3), a rotationai speed transmitter that is
connected in a rotationally fixed manner to the transmission shaft (3), and a
stationary rotational speed sensor (34), by means of which the rotational speed
can be detected by the rotational speed transmitter, characterized in that the
rotational speed transmitter is disposed on the periphery of an axially displaceabte
shift collar (20) of a coupling device (19) that is arranged in a rotationally fixed
manner on the transmission shaft (3).
2. The arrangement according to claim 1, characterized in that the
rotational speed sensor (34) is aligned in such a way that the rotational speed can
be detected in a radial direction by the rotational speed transmitter.
3. The arrangement according to one of the claims 1 or 2, characterized in that the shift collar (20) features externa! teeth (24) that can mesh with the inner teeth (22, 23) of a transmission part (16, 17) that is to be coupled, whereby the rotational speed transmitter is formed by the external teeth (24).
4. The arrangement according to claim 3, characterized in that the shift coiiar {2U) can be displaced from a neutral position to a first coupling position, in which the external teeth (24) mesh with the inner teeth (22, 23) of a first transmission part (16, 17) that is to be coupled.
5. The arrangement according to claim 4, characterized in that the shift collar (20) can be displaced farther from the neutral position in the opposite direction to a second coupling position, in which the external teeth (24) mesh with the internal teeth (23; 22) of a second transmission part (17; 16) that is to be coupled.
6. The arrangement according to one of the claims 4 or 5, characterized in that the rotational speed sensor (34) is arranged in such a way that the rotational speed in the neutral position, in the first coupling position, and in the second coupling position can be detected from the outer teeth (24).
7. The arrangement according to one of the previous claims, characterized in that a switch fork (28) is provided for displacing the shift collar (20).

8. An arrangement according to claim 7. characterized in that a peripheral
groove (25) is provided in the shiftcollar (20), which the switch fork (28) engages,
whereby the externa! teeth (24) feature two lateral external teeth sections (26,27),
between which the peripheral groove (25) extends, and the rotational speed in the
neutral position and in the first coupling position can be detected from one outer
teeth section (26; 27), and in the second coupling position from the other outer
teeth section (27; 26).
9. The arrangement according to one of the previous claims, characterized
in that the rotational speed sensor (34) is attached to a sensor arm (35) that
extends to the shift collar.
10. The arrangement according to claim 9, characterized in that the sensor
a.rm (35) is attached to a transmission housing (18) and extends through the
actuator space (32).
11. Then arrangement according to one of the claims 9 or 10, characterized
in that a sensor-side section (37) of the sensor arm (35) is configured in such a
way that the sensor arm in the neutral position, the first coupling position and/or
the second coupling position extends into or through the switch fork opening (33)
without collision.

sensor-side section (37) of the sensor arm (35) of the switch fork opening (33) is arranged opposite and disposed in an offset manner in the direction of the switch fork opening (33).
13. The arrangement according to one of the claims 9 to 12, characterized
in that a free wheel (16) is provided on the transmission shaft (3), that can be
coupled via the coupling device (19) to the transmission shaft (3), whereby on the
sensor arm (35) a gear set rotational speed sensor (38) is also provided, by means
of which the rotational speed of the free wheel (16) can be read from its teeth.
14. The arrangement according to one of the claims 3 to 13, characterized
in that the transmission part to be coupled (16, 17) is a free wheel on the
transmission shaft (3) or a stationary gear wheel on another transmission shaft.
15. The transmission for a motor vehicle featuring the arrangement
according to one of the previous claims.

16. The transmission according to ciaim 15, characterized in that the
transmission shaft (3) is the main shaft of the transmission (1), whereby in
addition, two countershafts (7, 8} are provided, between which the main shaft is
disposed in a floating manner.
17. A method of determining the rotational speed of a transmission shaft
with the methodological steps:
provision of a transmission with a transmission shaft and a coupling device that features an axialiy displaceable shift collar that is connected in a rotationally fixed manner to the transmission shaft, and
detection of the rotational speed on the periphery of the shift collar.