SENSOR ARRANGEMENT FOR AN AUTOMATED TRANSMISSION AND METHOD FOR DETECTING A MAGNETIC INTERFERENCE FIELD

Abstract

A sensor arrangement (46) for an automated transmission includes multiple axially parallel shift rails (4, 14, 24, 34) being axially displaceable by associated shift actuators (8, 18, 28, 38). The sensor arrangement (46) has multiple displacement sensors (48, 56, 64, 72) made up of a signal transmitter (50, 58, 66, 74) attached to a shift rail and a signal receiver (52, 60, 68, 76) fixedly arranged on a housing. The signal transmitters are in the form of a permanent magnet, and the signal receivers are in the form of a 3D Hall sensor. To detect an external magnetic interference field, which can corrupt the sensor signals from the displacement sensors (48, 56, 64, 72), the signal transmitters (50, 58, 66, 74) have identical axial alignments of their magnetic poles, and the signal receivers (52, 60, 68, 76) are in a common plane (80) that is horizontal in their installation position.

Claims

1. A sensor arrangement (46) for an automated transmission, comprising: a shifting device (2) including multiple shift rails (4, 14, 24, 34), which are arranged so as to be axially parallel to one another and which are axially displaceable by associated shift actuators (8, 18, 28, 38), wherein the sensor arrangement (46) includes multiple displacement sensors (48, 56, 64, 72), wherein each of the displacement sensors comprises a signal transmitter (50, 58, 66, 74) attached to one of the shift rails (4, 14, 24, 34) and a signal receiver (52, 60, 68, 76) fixedly arranged on a housing, wherein the signal transmitters (50, 58, 66, 74) are each in the form of a permanent magnet having magnetic poles, wherein the signal receivers (52, 60, 68, 76) are each in the form of a 3D Hall sensor, and wherein the signal receivers (52, 60, 68, 76) are each connected to an electronic transmission control unit (44) via electrical sensor lines (54, 62, 70, 78), wherein the signal transmitters (50, 58, 66, 74) are arranged having an identical axial alignment of their magnetic poles (N, S), and wherein the signal receivers (52, 60, 68, 76) are arranged in a common plane (80) that is horizontal in an installation position of the signal receivers.

2. A method for ascertaining an external magnetic interference field by a sensor arrangement (46) for an automated transmission having a has a shifting device (2) including multiple shift rails (4, 14, 24, 34) arranged axially parallel to one another and being axially displaceable by associated shift actuators (8, 18, 28, 38), wherein the sensor arrangement (46) has multiple displacement sensors (48, 56, 64, 72), each of which comprises a signal transmitter (50, 58, 66, 74) attached to one of the shift rails (4, 14, 24, 34) and a signal receiver (52, 60, 68, 76) fixedly arranged on a housing, wherein the signal transmitters (50, 58, 66, 74) are each in the form of a permanent magnet having magnetic poles, wherein the signal receivers (52, 60, 68, 76) are each in the form of a 3D Hall sensor, and wherein the signal receivers (52, 60, 68, 76) are connected to an electronic transmission control unit (44) via electrical sensor lines (54, 62, 70, 78), wherein the signal transmitters (50, 58, 66, 74) are arranged having an identical axial alignment of their magnetic poles (N, S), and wherein the signal receivers (52, 60, 68, 76) are arranged in a common plane (80) that is horizontal in an installation position of the signal receivers, the method comprising the steps of: detecting sensor signals of each of the signal receivers (52, 60, 68, 76) at a fixed interval (Δt.sub.S); storing current signal values (x.sub.S) of the sensor signals, and determining a presence of an external magnetic interference field in response to detecting that the signal values (x.sub.S) of at least two signal receivers (52, 60, 68, 76) simultaneously have a signal value change at a time when a gear change operation of the transmission has not been triggered.

3. The method as claimed in claim 2, wherein a mean value (x.sub.S_M) of the most recently detected signal values (x.sub.S) is formed for assessing the change of the signal values (x.sub.S) of each signal receiver (52, 60, 68, 76), wherein an inner tolerance range of the signal values (Δx.sub.S_T) about the particular mean value (x.sub.S_M) is defined, wherein an outer interference range of the signal values (Δx.sub.S_S) about the particular mean value (x.sub.S_M) is established, wherein an observation period (Δt.sub.B) including the particular most recently detected sensor signal is established, wherein a width of the inner tolerance range (Δx.sub.S_T) in each direction from the mean value corresponds to a particular strength of a magnetic interference field of +/−4 mT that is tolerable by the signal receivers (52, 60, 68, 76), wherein a width of the outer interference range (Δx.sub.S_S) in each direction from the mean value (x.sub.S_M) corresponds to a maximally assumed strength of an external magnetic interference field of +/−25 mT, and wherein an observation period (Δt.sub.B) is defined as a single-digit second range.

4. The method as claimed in claim 2, further comprising: detecting, at a time when a gear change operation of the transmission has not been triggered, that the sensor signals (x.sub.S1(t), x.sub.S2(t), x.sub.S3(t), x.sub.S4(t)) of all signal receivers (52, 60, 68, 76) have exceeded or fallen below an inner tolerance range (Δx.sub.S_T) at a beginning (t1) and at an end (t2) of an observation period (Δt.sub.B) and have remained within an outer interference range (Δx.sub.S_S); and in response thereto, detecting a magnetic interference field that is critical relative to a proper functioning of the shifting device (2).

5. The method as claimed in claim 2, further comprising: detecting, at a time when a gear change operation of the transmission has not been triggered, that the sensor signals (x.sub.S(t), x.sub.S2(t), x.sub.S3(t), x.sub.S4(t)) of all signal receivers (52, 60, 68, 76) have exceeded or fallen below an inner tolerance range (Δx.sub.S_T) at a beginning (t1) of an observation period (Δt.sub.B) and, thereafter, have remained within an outer interference range (Δx.sub.S_S), which range is greater than the inner interference range, detecting that the sensor signal (x.sub.S2(t)) of at least one signal receiver (60) has re-entered the inner tolerance range (Δx.sub.S_T) within the observation period (Δt.sub.B), and in response thereto, determining that a magnetic interference field that is critical relative to a proper functioning of the shifting device (2) is not present.

6. The method as claimed in claim 2, further comprising: detecting, at a time when a gear change operation of the transmission has not been triggered, that the sensor signals (x.sub.S1(t), x.sub.S2(t), x.sub.S3(t), x.sub.S4(t)) of all signal receivers (52, 60, 68, 76) have exited an inner tolerance range (Δx.sub.S_T) at a beginning (t1) of an observation period (Δt.sub.B), detecting, at a time when a shift request has occurred after the beginning of the observation period, that the sensor signal (x.sub.S2(t)) of at least one signal receiver (60) has exited an outer interference range (Δx.sub.S_S), which range is greater than the inner interference range, within the observation period (Δt.sub.B), and in response thereto, determining that a magnetic interference field that is critical relative to a proper functioning of the shifting device (2) is not present but the sensor signal (x.sub.S2(t)) of at least one signal receiver (60) has exited the interference range (Δx.sub.S_S) within the observation period (Δt.sub.B) due to a shift request that has occurred in the meantime.

7. The method as claimed in claim 2, further comprising, in response to detection of a magnetic interference field having a high field strength, due to which the sensor signals of the signal receivers (52, 60, 68, 76) could be corrupted, suppressing updating of the signal values.

8. The method as claimed in claim 2, further comprising, in response to detection of a magnetic interference field having a high field strength, due to which the sensor signals of the signal receivers (52, 60, 68, 76) could be corrupted, preventing a gear shift of the transmission.

9. The method as claimed in claim 2, further comprising, in response to detection of a magnetic interference field having a high field strength, due to which the sensor signals of the signal receivers (52, 60, 68, 76) could be corrupted, only permitting a gear shift of the transmission (2) into a certain forward gear and/or a certain reverse gear in order to make it possible to leave the magnetic interference field, wherein, in this gear shift, the sensor signals of the signal receivers (52, 60, 68, 76) are not accessed, and shift control is carried out for shifting time periods that are generous for a gear shift of this type.

10. The sensor arrangement of claim 1, wherein the electronic control unit receives signal values from the signal transmitters during an observation period, wherein the electronic control unit receives data corresponding to whether a gear change operation has been triggered during the observation period.

11. The sensor arrangement of claim 10, wherein the electronic control unit determines a presence of a magnetic interference field having high strength in response to detecting that the signal values (x.sub.S) of at least two signal receivers (52, 60, 68, 76) simultaneously have a signal value change at a time when a gear change operation of the transmission has not been triggered.

12. The sensor arrangement of claim 1, wherein the multiple shift rails comprise four shift rails, wherein one of the shift rails is associated with a two-stage splitter group connected upstream of a main transmission, two of the shift rails are associated with the main transmission, and one of the shift rails is associated with a two-stage range change group connected downstream from the main transmission.

13. The sensor arrangement according to claim 1, wherein each of the shift rails includes a shift fork rigidly mounted thereto and axially displaceable therewith.

14. The sensor arrangement according to claim 13, wherein the shift rails, shift forks, and signal transmitters move axially relative to the signal receivers that remain fixed in place.

15. The sensor arrangement according to claim 1, wherein the signal receivers are located at different axial positions relative to each other within the common plane.

16. The sensor arrangement according to claim 1, wherein an external magnetic field substantially identically affects all of the signal receivers.

17. The sensor arrangement according to claim 1, wherein each of the signal receivers detects an actuating position of the associated signal transmitters.

18. The sensor arrangement according to claim 1, wherein the ECU forms a mean value of the sensor signals and defines an inner tolerance range about the mean value and an outer interference range about the mean value that is greater than the inner tolerance range, and wherein the ECU establishes an observation period including a most recently detected sensor signal.

19. The sensor arrangement according to claim 18, wherein the inner tolerance range is +/−4 mT and the outer tolerance range is +/−25 mT.

20. The sensor arrangement according to claim 19, wherein the observation period is between 1 and 9 seconds.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Drawings with an exemplary embodiment accompanies the description to further illustrate the present disclosure. In the drawings:

[0031] FIG. 1 is a schematic top view of a shifting device of an automated transmission that includes four shift rails and a sensor arrangement according to the invention that includes four displacement sensors,

[0032] FIGS. 2a through 2d show first profiles of the sensor signals of the four displacement sensors according to FIG. 1 for ascertaining an external magnetic interference field,

[0033] FIGS. 3a through 3d show second profiles of the sensor signals of the four displacement sensors according to FIG. 1 for ascertaining an external magnetic interference field, and

[0034] FIGS. 4a through 4d show third profiles of the sensor signals of the four displacement sensors according to FIG. 1 for ascertaining an external magnetic interference field.

DETAILED DESCRIPTION

[0035] FIG. 1 shows a schematic top view of the shifting device 2 of an automated transmission of a countershaft design. The transmission is designed as a group transmission and includes a four-stage main transmission, a two-stage splitter group connected upstream from the main transmission, and a two-stage range change group connected downstream from the main transmission.

[0036] A first shift rail 4 is associated with the splitter group, the first shift rail 4 being arranged so as to be axially parallel to the transmission shafts (not shown) and is mounted in a transmission housing (not shown in greater detail) so as to be axially movable according to the first double-direction arrow 12. A first shift fork 6 is rigidly fixed on the first shift rail 4, the first shift fork 6 engaging, in a manner which is not shown, into a gear shift sleeve, which is guided on a transmission shaft in a rotationally fixed and axially displaceable manner. Due to an axial displacement of the first shift rail 4 and, thereby, of the associated gear shift sleeve, a change-over between two gear stages of the splitter group can be carried out. For this purpose, the first shift rail 4 is in an actuating connection with a first shift actuator 8, which is connected to an electronic transmission control unit 44 via a first electrical control line 10. The shift actuator 8 can be a hydraulic or pneumatic piston-cylinder arrangement, the pressure chambers of which are pressurizable with a pressure medium or are depressurizable via solenoid valves. An electric motor-operated or electromagnetic design of the first shift actuator 8 and also of all further shift actuators 18, 28, 38 is also possible, however.

[0037] A second and a third shift rail 14, 24, respectively, are associated with the main transmission, the second and the third shift rails 14, 24 being arranged so as to be axially parallel to each other and to the transmission shafts and to the first shift rail 4 of the splitter group. These two shift rails 14, 24 are mounted in the transmission housing so as to be axially movable according to the second and the third double-direction arrows 22, 32, respectively. A shift fork 16, 26 is rigidly fixed on each of these two shift rails 14, 24, respectively, the shift forks 16, 26 each engaging, in a manner which is not shown, into a gear shift sleeve, which is guided on a transmission shaft in a rotationally fixed and axially displaceable manner. Due to an axial displacement of one of these two shift rails 14, 24 in each case and, thereby, of the gear shift sleeve engaged with the associated shift fork 16, 26, a change-over can be carried out in each case between the shift positions of two gear stages of the main transmission and a neutral position, in which both gear stages are disengaged. For this purpose, the second and the third shift rails 14, 24, respectively, are in an actuating connection with an associated second and third shift actuator 18, 28, respectively, which are connected to the electronic transmission unit 44 via an electrical control line 20, 30, respectively.

[0038] A fourth shift rail 34 is associated with the range change group of the group transmission, the fourth shift rail 34 being arranged so as to be axially parallel to the transmission shafts and to the three other shift rails 4, 14, 24 and is mounted in the transmission housing so as to be axially movable according to the fourth double-direction arrow 42. A fourth shift fork 36 is rigidly fixed on the fourth shift rail 34, the fourth shift fork 36 engaging, in a manner which is not shown, into a gear shift sleeve, which is guided on a transmission shaft in a rotationally fixed and axially displaceable manner. Due to an axial displacement of the fourth shift rail 34 and, thereby, of the associated gear shift sleeve, a change-over between two gear stages of the range change group can be carried out. For this purpose, the fourth shift rail 34 is in an actuating connection with a fourth shift actuator 38, which is connected to the electronic transmission control unit 44 via an electrical control line 40.

[0039] An associated sensor arrangement 46 includes four displacement sensors 48, 56, 64, 72. These displacement sensors 48, 56, 64, 72 are each made up of a signal transmitter 50, 58, 66, 74, respectively, which is attached to one of the four shift rails 4, 14, 24, 34, respectively, and is in the form of a permanent magnet, and a signal receiver 52, 60, 68, 76, which is fixedly arranged on the housing and is in the form of a 3D Hall sensor. The signal receivers 52, 60, 68, 76 are connected to the electronic transmission control unit 44 via associated electrical sensor lines 54, 62, 70, 78, respectively.

[0040] According to the invention, signal transmitters 50, 58, 66, 74 in the form of permanent magnets are arranged having an identical axial alignment of their magnetic poles N, S, and the signal receivers 52, 60, 68, 76 in the form of 3D Hall sensors are arranged in a common plane 80 that is horizontal in their installation position. In FIG. 1, this horizontal plane 80 corresponds to the plane of the drawing. Due to the arrangement of the displacement sensors 48, 56, 64, 72 according to the present disclosure, an external magnetic interference field largely identically affects all four signal receivers 52, 60, 68, 76 or 3D Hall sensors, and so the presence of a strong magnetic interference field, due to which the actuating position signals of the signal receivers 52, 60, 68, 76 can become corrupted, can be detected by evaluating the sensor signals x.sub.S1, x.sub.S2, x.sub.S3, x.sub.S4 of all signal receivers 52, 60, 68, 76.

[0041] The sensor signals x.sub.S1, x.sub.S2, x.sub.S3, x.sub.S4 of the signal receivers 52, 60, 68, 76 designed as 3D Hall sensors are detected in the form of the particular sensed actuating position at a fixed interval Δt.sub.S and stored as a current signal value x.sub.S_akt of each Hall sensor 52, 60, 68, 76, respectively. The presence of an external magnetic interference field is detected due to the fact that the most recently detected sensor signals x.sub.S of all signal receivers 52, 60, 68, 76 simultaneously have a signal value change without the presence of an active shift request or a transmission shift that is currently underway. Because the actuating speed of the shift rails 4, 14, 24, 34 is considerably higher than the ground speed of a vehicle in the proximity of loading points, which is at most 30 km/h, a signal value change in the sensor signals x.sub.S1, x.sub.S2, x.sub.S3, x.sub.S4 can be clearly differentiated from a change in a sensor signal due to a gear change operation or a selection operation. The passage through or the switching on and off of a magnetic interference field can also be detected on the basis of the time profiles of the sensor signals x.sub.S(t).

[0042] For this purpose, it is provided that a mean value x.sub.S_M of the most recently detected sensor signals x.sub.S is formed for assessing the signal value change in the sensor signals x.sub.S(t) of each signal receiver 52, 60, 68, 76. An inner tolerance range Δx.sub.S_T and an outer interference range Δx.sub.S_S about the particular mean value x.sub.S_M are defined for the sensor signals x.sub.S(t). The values of the inner tolerance range Δx.sub.S_T are lower than the values of the outer interference range Δx.sub.S_S. In addition, an observation period Δt.sub.B including the particular most recently detected sensor signal x.sub.S is established.

[0043] The width of the tolerance range Δx.sub.S_T corresponds in each direction to the strength or magnetic flux density of a magnetic interference field that is tolerable by the signal receivers 52, 60, 68, 76, which is, for example, +1-4 mT in the present case. The width of the interference range Δx.sub.S_S corresponds in each direction to the maximally assumed strength or magnetic flux density of an external magnetic interference field of, for example, +1-25 mT in the present case. The observation period Δt.sub.B is defined as a single-digit second range and can be between 1 second and 9 seconds in this exemplary embodiment.

[0044] The assessment of the time profiles of the sensor signals x.sub.S1(t), x.sub.S2(t), x.sub.S3(t), x.sub.S4(t) of the four signal receivers 52, 60, 68, 76 in the form of 3D Hall sensors with respect to the presence of a magnetic interference field is described in the following with reference to three examples shown in FIGS. 2a, 2b, 2c, 2d; 3a, 3b, 3c, 3d; 4a, 4b, 4c, 4d.

[0045] In the first example shown in FIGS. 2a, 2b, 2c, 2d, it is apparent that the signal values x.sub.S of the sensor signals x.sub.S1(t), x.sub.S2(t), x.sub.S3(t), x.sub.S4(t) of all four signal receivers 52, 60, 68, 76 in the form of 3D Hall sensors have exceeded the inner tolerance range Δx.sub.S_T at the beginning of the observation period Δt.sub.B (point in time t1) and at the end of the observation period Δt.sub.B (point in time t2) and have remained within the external interference range Δx.sub.S_S. Due to the largely identical signal value change detected in all time profiles of the sensor signals x.sub.S1(t), x.sub.S2(t), x.sub.S3(t), x.sub.S4(t) and the absence of an active shift request, the presence of a critical external magnetic interference field is detected in this case.

[0046] In the second example shown in FIGS. 3a, 3b, 3c, 3d, it is apparent that the signal values x.sub.S of the sensor signals x.sub.S1(t), x.sub.S3(t), x.sub.S4(t) of the first, the third, and the fourth signal receivers 52, 68, 76, respectively, according to FIGS. 3a, 3c, 3d have exceeded the inner tolerance range Δx.sub.S_T at the beginning of the observation period Δt.sub.B (point in time t1) and at the end of the observation period Δt.sub.B (point in time t2) and have remained within the outer interference range Δx.sub.S_S. By comparison, the signal values x.sub.S of the sensor signal x.sub.S2(t) of the second signal receiver 60 according to FIG. 3b have in fact exceeded the inner tolerance range Δx.sub.S_T at the beginning of the observation period Δt.sub.B (point in time t1), however, the signal values x.sub.S of the sensor signal x.sub.S2(t) of the second signal receiver 60 have re-entered the tolerance range Δx.sub.S_T at the point in time t2′ prior to the end of the observation period Δt.sub.B. Because an active shift request is not present and the time profile of the sensor signal x.sub.S2(t) of the second signal receiver 60 permits the inference of an only short-term influence of the sensor signals x.sub.S1(t), x.sub.S2(t), x.sub.S3(t), x.sub.S4(t) of all signal receivers 52, 60, 68, 76, the presence of a critical external magnetic interference field can be assessed in this case as not having been detected.

[0047] In the third example shown in FIGS. 4a, 4b, 4c, 4d, it is apparent that the signal values x.sub.S of the sensor signals x.sub.S1(t), x.sub.S3(t), x.sub.S4(t) of the first, the third, and the fourth signal receivers 52, 68, 76, respectively, according to FIGS. 4a, 4c, 4d have exceeded the inner tolerance range Δx.sub.S_T at the beginning of the observation period Δt.sub.B (point in time t1) and at the end of the observation period Δt.sub.B (point in time t2) and have remained within the outer interference range Δx.sub.S_S. By comparison, according to FIG. 4b, the signal values x.sub.S of the sensor signal x.sub.S2(t) of the second signal receiver 60 have in fact exceeded the inner tolerance range Δx.sub.S_T at the beginning of the observation period Δt.sub.B (point in time t1) but, shortly thereafter, at the point in time t1′, have exceeded the outer interference range Δx.sub.S_S due to a shift request or transmission shift that has occurred in the meantime. Therefore, the presence of a critical magnetic interference field is also considered not to have been detected in this case.

LIST OF REFERENCE SIGNS (PART OF THE DESCRIPTION)

[0048] 2 shifting device [0049] 4 first shift rail [0050] 6 first shift fork [0051] 8 first shift actuator [0052] 10 control line [0053] 12 first double-direction arrow [0054] 14 second shift rail [0055] 16 second shift fork [0056] 18 second shift actuator [0057] 20 control line [0058] 22 second double-direction arrow [0059] 24 third shift rail [0060] 26 third shift fork [0061] 28 third shift actuator [0062] 30 control line [0063] 32 third double-direction arrow [0064] 34 fourth shift rail [0065] 36 fourth shift fork [0066] 38 fourth shift actuator [0067] 40 control line [0068] 42 fourth double-direction arrow [0069] 44 electronic transmission control unit, ECU [0070] 46 sensor arrangement [0071] 48 first displacement sensor [0072] 50 first signal transmitter, permanent magnet [0073] 52 first signal receiver, 3D Hall sensor [0074] 54 sensor line [0075] 56 second displacement sensor [0076] 58 second signal transmitter, permanent magnet [0077] 60 second signal receiver, 3D Hall sensor [0078] 62 sensor line [0079] 64 third displacement sensor [0080] 66 third signal transmitter, permanent magnet [0081] 68 third signal receiver, 3D Hall sensor [0082] 70 sensor line [0083] 72 fourth displacement sensor [0084] 74 fourth signal transmitter, permanent magnet [0085] 76 fourth signal receiver, 3D Hall sensor [0086] 78 sensor line [0087] 80 horizontal plane [0088] N magnetic north pole [0089] S magnetic south pole [0090] t time [0091] t1, t2 points in time [0092] t1′, t2′ points in time [0093] Δt.sub.B observation period [0094] Δt.sub.S interval [0095] x.sub.S signal values of a sensor signal; signal values [0096] x.sub.S(t) time profile of a sensor signal [0097] x.sub.S1(t) time profile of the sensor signal of the first signal receiver [0098] x.sub.S2(t) time profile of the sensor signal of the second signal receiver [0099] x.sub.S3(t) time profile of the sensor signal of the third signal receiver [0100] x.sub.S4(t) time profile of the sensor signal of the fourth signal receiver [0101] x.sub.S_akt current signal value [0102] x.sub.S_M mean value of the signal values [0103] Δx.sub.S_T tolerance range of the signal values [0104] Δx.sub.S_S interference range of the signal values