CN116075659A

CN116075659A - Switching element and switching device having a switching element

Info

Publication number: CN116075659A
Application number: CN202180062396.0A
Authority: CN
Inventors: 安德烈亚斯·舒尔特; 本杰明·卡夫纳; 多米尼克·迈登鲍尔
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Holding China Co Ltd
Priority date: 2020-10-08
Filing date: 2021-09-08
Publication date: 2023-05-05
Also published as: WO2022073537A1; DE102020126396A1; DE102020126396B4

Abstract

The invention relates to a switching element (1) having: an envelope contour (2); two blind holes (3, 4) each having a blind hole bottom (13, 14) and a blind hole wall (23, 24) and being axially spaced apart from each other by a shift element intermediate section (5); two magnets (6, 7) which are each arranged in one of the blind holes (3, 4) and together form a signal generator for determining the position of the shift element (1), wherein the blind hole walls (23, 24) are formed at an angle to the radial direction in the region thereof pointing towards the shift element intermediate section (5).

Description

Switching element and switching device having a switching element

Technical Field

The invention relates to a switching element for a motor vehicle gearbox, said switching element having: envelope profile; two blind holes each having a blind hole bottom and a blind hole wall and being axially spaced apart from each other by a shift element intermediate section; two magnets which are each arranged in one of the blind holes and together form a signal generator for determining the position of the switching element. The invention also relates to a switching device having such a switching element.

Background

Shift elements of this type are used in particular in manual shift transmissions, but also in automatic shift transmissions or automatic transmissions of motor vehicles. It is increasingly necessary to be able to determine the exact position of the shift element, in particular the shift shaft.

According to the prior art known in advance, the position recognition of the switching element is based on the principle of detecting a locally changing magnetic field by means of the hall effect. Thus, EP 1,350,991 B1 discloses a sensor device for determining the position of a shift drum, wherein a detector samples the profiled circumferential surface of a sensor disk fixedly connected to a shift shaft. The position of the sensor is measured without contact, and then the shift position is determined by means of a hall element. With this solution, usually hall sensors are used which are switched on and are designed to detect discrete shift positions. In the case of using a hall switch, only binary state information of the switching element is obtained so that an accurate position is not obtained. And therefore the intermediate position cannot be detected.

In order to solve the problem, there are solutions for continuous stroke measurement, which are based on measuring the flux density of the magnet or the angular variation of the magnetic field. Such switching devices are known from DE10 2006 01207a 1 and US 2009/0 001 971a 1. DE10 2009 051 125 A1 shows an eddy current sensor, in DE10 2013 205 901 A1 the magnetic field is linearized by a ferromagnetic element. According to DE10 2015 200 802 A1 the rotation angle should be converted, but this also converts the measurement error.

Other switching devices are known from DE10 2008 052 416 A1, DE10 2008 063 598 A1, DE10 2017 002 873a1 and DE 197 48 a 1.

However, the signals of the magnets for continuous travel measurement disadvantageously have a high temperature dependence in the case of flux density measurement or are characterized by a high nonlinearity in the case of angular change measurement. Thus, compensation, linearization or learning for each individual switching device requires high effort. Furthermore, high demands are placed on the components, the series dispersion of which should be only very small.

Furthermore, the accuracy of the travel measurement is related to the strength of the magnetic field. In particular, in the relevant measuring region, the magnetic field strength must adhere to specific limit values in order to be able to be reliably evaluated by the measuring electronics. Between the magnets, the field strength has a minimum value. In order to ensure the necessary minimum field strength there, a magnet with a stronger relative field strength is required, which is associated with high costs.

Disclosure of Invention

The invention is based on the object of providing a switching element with a signal generator, the successive position detection of which is possible even with the aid of a low-field magnet. Furthermore, it is an object of the invention to provide a switching device with such a switching element.

The object is achieved by the device according to claims 1 and 9. The improvements of the device according to claim 1 are the subject of the dependent claims 2 to 8. The two blind bores are arranged axially one after the other at the shift element and are separated from one another by a shift element intermediate section. A magnet is disposed in each of the blind holes. The magnets together form a signal generator, which can be used by the sensor to determine the position of the switching element.

The material missing at the transition of the blind hole to the switching element at the radially outer transition changes the field line profile of the magnet. In particular, the magnetic field strength in the air gap surrounding the switching element is thereby uniform, so that the minimum field strength thereby also increases there, even if a load is applied to the field strength in the further region. The present invention allows for weaker magnets to be used because it is adapted to the minimum field strength when sizing the magnets.

On an imaginary connecting line through the two magnets, a ferromagnetic material may be arranged between the two magnets. The ferromagnetic material arranged at the location causes the magnetic field lines to be deformed onto the vertical lines, which, without the material, are at a larger angle to the surface of the switching element. By said parallelization of the field lines in the polar environment, the magnetic field variations can be detected more easily with a predetermined radial distance from the switching element.

The two magnets are disposed axially spaced apart from one another. The two magnets are preferably configured as permanent magnets. The two magnets can be, for example, rectangular bar magnets or bar magnets of cylindrical design. The two magnets are preferably identical in terms of their field strength and their outer dimensions.

The two magnets are preferably arranged opposite to each other with respect to the magnetic field generated by them.

The two magnet elements are arranged such that the magnetic field lines emanating from the center of the magnet elements are perpendicular to the axial direction of movement of the switching element. The two magnet elements are preferably arranged at the same distance from the switching axis of the switching element.

Preferably, the magnet is held at the switching element only by its magnetic properties and is not additionally fixed, for example, in a material-fitting manner. The ferromagnetic switching element is for this purpose made of a steel alloy, for example. However, the magnets can also be fixed in a form-fitting and/or force-fitting manner.

The magnet is arranged in a blind hole of the switching element. The blind hole forms a radially directed recess in the outer side of the shift element. The blind hole preferably has a profile complementary to that of the magnet. This prevents the magnet from falling off or accidentally scraping off during installation, so that additional, costly fastening measures can be dispensed with. Nevertheless, the magnet can be additionally fixed in the recess, for example glued or sprayed with plastic.

The blind holes are respectively provided with a blind hole bottom and a blind hole wall. For example, the blind holes are formed cylindrically and/or can be drilled. Alternatively, the blind hole is formed in a truncated spherical or rectangular parallelepiped shape. The latter blind holes can be produced by stamping. The blind hole wall extends radially so as to be arranged at an angle to the direction of movement of the switching element.

The switching element is movable in at least one direction defining an axial direction. In addition, the shift element can be twisted (shift shaft) or can be designed as a shift lever which is axially displaceable only and is fixed in the circumferential direction. The switching element may have a circular cross section or a rectangular cross section as a switching track, for example. The blind holes may be arranged in succession in the circumferential direction or offset from one another. The shift element may also be a shift fork or a component that is otherwise movable in a transmission of a motor vehicle gearbox, for example a movable component of a parking lock.

The intermediate section of the shift element is the section of the shift element that is formed on an imaginary connecting line between the two blind hole walls. The blind hole wall extends substantially radially. The blind hole wall may be formed at an angle to the radial direction in the transition region pointing towards the switching element intermediate section. The angle may be made by beveling, rounding or otherwise material removal. Preferably, the angle is formed circumferentially, so that the blind hole has a symmetrical transition region.

Alternatively, the blind holes may be configured as stepped holes. In which case the post-treatment can be omitted if necessary.

In a further variant, the blind holes are arranged in a common axial groove. In this case, the magnet protrudes radially from the blind hole, but preferably does not pass through the envelope circle of the switching element. The switching element can thereby be supported on its outer side without the bearing having to be adapted to the protruding magnet. The outer contour of the switching device thus formed by the shift shaft and the magnet is flattened in the region of the blind hole, wherein the wall surrounding the magnet is produced on both sides of the magnet in the axial direction. The outer contour is thus formed, as seen in longitudinal section, by an envelope circle of the outer side of the switching device, which extends parallel to the axis of rotation and which is offset radially inward only in the region of the blind hole.

The magnetic field of the signal generator is detected by a sensor, preferably fixed to the transmission housing. The sensor and the magnet are preferably moved relative to each other with a constant spacing being maintained with the formation of an air gap. The sensor is preferably connected to an evaluation device which is designed to further process the measured signal, for example the magnetic field direction, into an axial position.

With the proposed concept, a continuous measurement of the magnetic field can be achieved with sufficient accuracy for a continuous position determination of the switching element. The measured signal is already a linear or well linearised signal which allows an accurate axial position determination of the switching element relative to the housing. For this purpose, the magnetic field generated by the two magnets is detected in terms of direction and/or strength by the sensor and the axial position is determined therefrom. The two magnets are arranged one after the other in the measuring direction, whereby the magnetic field direction is essentially proportional to the axial position and insensitive to disturbance variables.

This can be achieved by using two magnets which are magnetized relative to one another and are arranged side by side in the measuring direction and preferably have the same strength. With a suitable spacing between the magnets, a minimum linear error of the measured variable is advantageously obtained for a specific air gap over the measuring stroke. Furthermore, the ideal air gap in the configuration is smaller than typical with simple magnets, which additionally has a positive impact on the solution's integrability.

The shift element according to the invention can be supported directly in the transmission housing. Preferably, the switching element is supported in a housing, in which a sensor for detecting the field lines of the magnet is integrated. The housing and the switching element with the magnet form a switching device. The switching device may in particular have a plurality of rows of metallic rolling bodies arranged in succession, which rolling bodies roll directly adjacent to the magnets on the switching element without the measurement accuracy being significantly impaired.

Drawings

In the drawings an embodiment according to the invention is shown. The drawings show:

figure 1 shows a schematic view of a switching element according to the invention in a switching device with a sensor bearing,

figures 2a and 2b show in perspective and longitudinal section a first embodiment of a switching element according to the invention for use in figure 1,

figures 3a and 3b show in perspective and longitudinal section a second embodiment of a switching element according to the invention for use in figure 1,

figures 4a and 4b show in perspective and longitudinal section a third embodiment of a switching element according to the invention for use in figure 1,

fig. 5a, 5b show in perspective view and longitudinal section a fourth embodiment of a switching element according to the invention for fig. 1, and

fig. 6 shows in longitudinal section a switching element for fig. 1 without an optimized blind hole contour, and

fig. 7 shows a schematic illustration of the magnetic field strength detected by the sensor of the switching element according to fig. 2b and 6.

Detailed Description

Fig. 1 shows a part of a shifting device 9 of a gear change of a motor vehicle, the basic construction of which is known. By means of a not shown actuating element, the shift element 1 in the form of a shift shaft can be moved axially in the housing 10 in the direction of its longitudinal axis 22. By means of the shift element 1, a shift fork, not shown, can be moved and a shift process is performed in this way. For this purpose, the switching element is mounted in a sensor bearing 20, the sleeve contour 14 and the sensor 11 of which are shown here. The axial position of the sleeve contour can be fixed by a not shown locking element which is preloaded against the locking contour 24.

The determination of the axial position of the switching element 1 is achieved by means of a sensor device formed by the two

magnets

6,7 and the sensor 11 as a signal generator pair. The first magnet 6 and the second magnet 7 are arranged on the switching element 1 in a stationary manner. Thus, the two

magnets

6,7 have a defined spacing relative to each other. The

magnets

6,7 embodied as permanent magnets are arranged in opposite directions, i.e. the north and south poles are oriented in opposite directions. The sensors 11 are arranged at a radial distance from the switching element 1 and are separated by an air gap. The sensor 11 is fixedly arranged at the housing 10.

As a result of the magnetic field generated by the two

magnets

6,7, a local direction of the magnetic field is derived via the axial movement direction at each location, which can be detected by the sensor 11; thus, the sensor 11 can detect an angle at which the magnetic field is at a desired axial position. This applies in any case on the selected measuring region, where there is a high degree of linearity between the angular and axial position of the switching element 1.

Fig. 2a and 2b show a first switching element 1 having two

blind bores

3,4 which are arranged axially offset from one another and each have a blind bore base 13 and a blind bore wall 23. The depth of the two blind holes is identical, so that they have the same distance from the central axis 19 of the switching element 1. Between the two

blind holes

3,4 there is the material of the shift element 1, which forms a shift element intermediate section 5. The

blind holes

3,4 are arranged at the same circumferential angle and have the same contour. In each of the blind holes 3,

4a magnet

6,7 is provided. The two

magnets

6,7 have the same external dimensions and the same field strength. The

magnets

6,7 each rest against the blind hole wall 23 in the inner first blind hole section 17. However, the magnets are spaced apart from the blind hole wall 23 in the outer second blind hole section 18 and form a transition region. The transition region is formed as a bevel 15 with an angle of 30 ° so as to form a cone. The radial depth of the inner and outer

blind hole sections

17, 18 is approximately the same.

The shift element 1 embodied as a selector lever has an envelope contour 2. The

magnets

6,7 do not extend in the radial direction 12 up to the envelope contour 2, but are retracted from said envelope contour with a gap 21.

The

blind holes

3,4 of fig. 3a and 3b differ from the blind holes of fig. 2a and 2b in that: the blind holes are configured as stepped holes. The stepped bore has an annular shoulder 25. The

magnets

6,7 are also held in an inner first blind hole section 17 which extends up to an annular shoulder 25. The outer second blind hole section 18 is connected radially outward to the annular shoulder 25, said outer second blind hole section first extending radially and further also having a chamfer 15 radially outward.

In the embodiment according to fig. 4a and 4b, the

blind holes

3,4 are arranged in a common axial groove 8. The chamfer 15 can thus be omitted depending on the width of the axial groove, since by the axial groove 8 itself it is ensured that the

magnets

6,7 are not surrounded by ferromagnetic material at least in the region facing each other in their radially outer sections.

As can be seen from fig. 5a and 5b, the release switching element intermediate section 5 is not realized by a chamfer 15, but by a radius 16. Instead of the radius 16, the switching element intermediate section 5 may also have a further rounding or geometry which ensures that the

magnets

6,7 are spaced apart from the switching element intermediate section 5 at least in the radially outer region.

Since the switching element can only be moved in a limited manner, it is sufficient if only the area of the switching element 1, which is swept over the measuring section, is provided with a trip. It is therefore generally sufficient if the chamfer 15, the radius 16, the axial groove 8 are provided only in the region of the shift element intermediate section 5. In all embodiments, the

magnets

6,7 sink in the switching element 1 and do not protrude radially beyond the envelope circle, the envelope contour 2, the outer side of the switching element 1. Thereby, an air gap is present with respect to the sensor 11 and it is ensured that the

magnets

6,7 do not pass through the housing 10 and thus assume a bearing function.

Fig. 6 shows a switching element 1 according to the prior art, which has two

magnets

6,7 and a switching element intermediate section 5 which radially completely surrounds the

magnets

6, 7. The blind bore wall 23 has radial sections 25 which project radially from the

magnets

6, 7. The radial sections 25 of the blind hole wall deform the magnetic field of the

magnets

6,7 and attenuate the magnetic field.

Fig. 7 shows the field strength measured by the sensor 11 as a function of the axial position of the switching element 1. The highest field strength of the switching element 1 according to fig. 6 is here set at 100%. As can be read from curve VI, in the embodiment described, the minimum field strength is approximately 20% of the maximum.

Curve II shows the field strength of the switching element 1 according to fig. 2a, 2b, which differs from the switching element 1 of curve 6 only in the presence of the bevel 15. In particular, the field strength of the

magnets

6,7 used is as high. The maximum value of the detected field strength is about 30% higher. It is decisive that the field strength detected in the entire measuring region is higher than the offset. The offset fluctuates less strongly with the travel than the absolute field strength, so that the minimum field strength is at 40% relative units. Whereby the minimum field strength is twice as high as the field strength of the switching element according to fig. 2. Since the minimum field strength is decisive for the dimensioning of the magnets, the invention makes it possible to use weaker magnets in order to achieve the same measurement accuracy.

List of reference numerals

1. Switching element

2. Envelope profile

3. First blind hole

4. Second blind hole

5. Intermediate section of switching element

6. First magnet

7. Second magnet

8. Axial groove

9. Switching device

10. Shell body

11. Sensor for detecting a position of a body

12. Radial direction

13. Bottom of blind hole

14. Sleeve profile

15. Inclined plane

16. Radius of radius

17. An inner first blind hole section

18. An outer second blind hole section

19. Central axis

20. Sensor bearing

21. Gap of

22. Longitudinal axis

23. Blind hole wall

24. Locking profile

25. Radial segment

II field strength of the axial position of the switching element according to fig. 2a, 2b

VI field strength according to the axial position of the switching element of FIG. 6

Claims

1. A switching element (1) axially movable along a longitudinal axis (22) for a motor vehicle change-speed gearbox, said switching element having:

an envelope contour (2),

two blind holes (3, 4) each having a blind hole bottom (13) and a blind hole wall (23) having a first blind hole section (17) which is internal in the radial direction (12) and a second blind hole section (18) which is external in the radial direction (12),

a switching element intermediate section (5) arranged between the two blind holes (3, 4),

two magnets (6, 7) which are each arranged in one of the blind holes (3, 4) and together form a signal generator for determining the position of the switching element (1),

characterized in that the magnets (6, 7) are set back in the radial direction (12) relative to the envelope contour (2) and in that they rest against the blind wall 23 in the inner first blind hole section (17) and in that they are spaced apart from the blind wall 23 in the outer second blind hole section (18).

2. Switching element (1) according to claim 1, characterized in that the blind hole wall (23, 24) is formed at an angle to the radial direction (12) in its transition region (33, 34) directed towards the switching element intermediate section (5).

3. Switching element (1) according to claim 2, characterized in that one of the blind hole walls (23) has a bevel (15).

4. Switching element (1) according to claim 2, characterized in that one of the blind hole walls (23) is rounded with a radius (16).

5. Switching element (1) according to any one of the preceding claims, characterized in that one of the blind hole walls (23) is configured as a stepped recess.

6. Switching element (1) according to any one of the preceding claims, characterized in that the two blind holes (3, 4) are arranged in a common axial groove (8).

7. The switching element (1) according to any of the preceding claims, characterized in that the switching element (1) has an envelope contour (2) with respect to which the switching element intermediate section (5) is radially indented.

8. Switching element (1) according to any of the preceding claims, characterized in that the magnets (6, 7) are held directly in the switching element (1).

9. A switching device (9) of a motor vehicle gear shifting box, having a housing (10) with a sensor (11) and a switching element (1) according to any of the preceding claims.