SE2250686A1

SE2250686A1 - Magnetic field sensor

Info

Publication number: SE2250686A1
Application number: SE2250686A
Authority: SE
Inventors: Torsten Wahler
Original assignee: Continental Automotive Gmbh
Priority date: 2021-06-25
Filing date: 2022-06-07
Publication date: 2022-12-26
Also published as: DE102021206620A1; FR3124601A1

Abstract

The invention relates to a magnetic field sensor 1 with a device housing 6 having a sensor element housing part 2 and a connection housing part 4, wherein the sensor element housing part 2 is formed as a pot and is closed at a first sensor element housing part end 8 by the pot base 10 of the pot, and wherein the connection housing part 4 is arranged at the second sensor element housing part end 12. To improve the protection of the magnetic field sensor against possible manipulations, it is proposed that the connection housing part 4 closes the sensor element housing part 2 and is arranged completely within the sensor element housing part 2, and that the connection housing part 4 and the sensor element housing part 2 are connected to one another by means of a latching connection 16, wherein the latching connection 16 has a surface step 18 on the inner side 20 of the sensor element housing part 2 and a latching lug 22 on the connection housing part 4, which latching lug engages behind the surface step 18.

Description

Description Title of the lnvention Magnetic field sensor The invention relates to a magnetic field sensor with a device housing having a sensor element housing part and a connection housing part, wherein the sensor element housing part is formed as a pot and is closed at a first sensor element housing part end by the pot base of the pot and wherein the connection housing part is arranged at the second sensor element housing part end.

Such a magnetic field sensor is known for example as a so-called speed sensor or rotary encoder or an inductive transmitter for a tachograph in a motor vehicle, in particular a commercial vehicle. The magnetic field sensor has a sensor head and is screwed into a transmission housing of a transmission of the motor vehicle. The magnetic field sensor uses the sensor head to detect a movement of a transmission gearvvheel of the transmission. The movement of the transmission gearvvheel is a measure of the speed of the motor vehicle. A part of the sensor element housing part, namely the part which also has the pot base, is a component part of the sensor head. The magnetic field sensor is connected to the tachograph of the motor vehicle via the connection housing part. Given the required high degree of reliability of data recorded by the tachograph, it is of importance, inter alia, to avoid and to prevent a manipulation of the magnetic field sensor and, resulting from such a manipulation, data adulterations. lt is an object of the invention to provide a magnetic field sensor of the type stated at the outset that has a high degree of security against manipulation.

This object is achieved according to the invention in that the connection housing part closes the sensor element housing part and is arranged completely within the sensor element housing part and in that the connection housing part and the sensor element housing part are connected to one another by means of a latching connection, wherein the latching connection has a surface step on the inner side 202100583 of the sensor element housing part and a latching lug on the connection housing part, which latching lug engages behind the surface step.

A particular advantage in the case of the magnetic field sensor according to the invention is the provision of the latching connection between the sensor element housing part and the connection housing part along with the arrangement of the connection housing part within the sensor element housing part. Prohibited separation of the sensor element housing part and the connection housing part, which might be carried out with manipulative intent in order to gain access to the interior of the magnetic field sensor, may therefore be made apparent in a particularly reliable manner since it is virtually impossible to remove the connection housing part, which is arranged completely within the sensor element housing part, without damage being apparent from the outside. Given that the sensor element housing part is closed at the bottom by means of the pot base, the connection housing part also cannot be pushed out of the sensor element housing part from the first sensor element housing part end. Manipulations of the device housing of the magnetic field sensor are therefore reliably apparent.

The pot base of the sensor element housing part which is formed as a pot is a component part of the pot. The pot base and the pot are therefore formed in one piece. The sensor element housing part may be for example a metal component.

The connection housing part serves for electrically connecting the magnetic field sensor for example to vehicle electronics. The magnetic field sensor may be connected in particular to a tachograph via the connection housing part. The connection housing part may preferably be a plastics component. By way of example, electrical connection contacts may be injection molded into such a plastics component.

A particular advantage of the invention is also the provision of a latching connection instead of for example a screw connection between the connection housing part and the sensor element housing part. ln contrast to a screw connection, for example, the latching connection is non-releasable, at least it is not releasable without destruction. The connection housing part preferably forms a 202100583 3 housing cover of the device housing. ln this case, this housing cover is arranged in the sensor element housing part and latched thereto. The connection housing part, in particular if it is formed as a housing cover, therefore locks the device housing and protects the interior of the device housing against unauthorized access.

The housing of the magnetic field sensor, which is formed by the device housing, is advantageousiy integra| with the single receptacle of the connection housing part which simultaneously serves as a closure and is inserted into the sensor element housing part.

The device housing of the magnetic field sensor has a longitudinal axis, wherein the longitudinal axis is that axis of the device housing which corresponds to the direction of its greatest extent. The longitudinal axis of the device housing is preferably also the longitudinal axis of the magnetic field sensor. During assembly of the magnetic field sensor, the connection housing part and the sensor element housing part are preferably joined in the direction of the longitudinal axis of the device housing.

The device housing of the magnetic field sensor may have in particular a cylindrical form. This results in a cylindrical magnetic field sensor. The magnetic field sensor is preferably rod-shaped. The magnetic field sensor may be in particular a speed sensor or rotary encoder, namely in particular for a tachograph. The magnetic field sensor is further preferably an inductive transmitter. The inductive transmitter has for example a Hall element as a sensor element.

The device housing of the magnetic field sensor preferably consists of only two components, that is to say the sensor element housing part and the connection housing part. Therefore, since the connection housing part is arranged within the sensor element housing part, a device housing is created which is seamless from the outside and does not permit prohibited opening, since assembly-related seams are not present. The fundamental components of the magnetic field sensor, for example a sensor element and evaluation electronics, are arranged in a protected manner in the device housing. Prohibited opening of the device housing cannot be 202100583 4 even provisionally concealed, but instead remains apparent. At the same time, the production costs for the magnetic field sensor may be reduced.

Additional advantageous developments of the invention are specified in the subclaims.

According to an advantageous development of the invention, the sensor element housing part has, on its outer side, a mechanical connection element at the second sensor element housing part end. The mechanical connection element may have for example a bayonet coupling contour. Owing to the mechanical connection element of the sensor element housing part, a plug connector, for example, which has this mechanical connection element and the connection housing part serving for the electrical connection of the magnetic field sensor, may be advantageously formed on the second sensor element housing part end. A plug of a connection cable, for example, may be connected to the plug connector, which connection cable, by way of example, connects the magnetic field sensor to a tachograph. Since the mechanical connection element is a component part of the sensor element housing part, an external seam between the device housing and the plug connector, which may possibly be acted upon with manipulative intent, is not present. A seal which would possibly be required for such a seam is moreover omitted. lt is in principle conceivable, for example, that the connection housing part has, by way of example, one or more connection cables leading out of the device housing of the magnetic field sensor. On the other hand, an advantageous development of the invention provides for the connection housing part to have at least two electrical connection contacts on its outer side. The connection contacts may be injected molded into the connection housing part, for example. The connection housing part may preferably have two to four, further preferably precisely four, electrical connection contacts. The electrical connection contacts may be formed in particular in the shape of a pin. Such pin-shaped connection contacts may also be referred to as contact pins. The electrical connection contacts are preferably aligned parallel to the longitudinal axis of the magnetic field sensor. A mechanical connection element of the sensor element housing part and the electrical 202100583 5 connection contacts of the connection housing part preferably form a plug connector, e.g. for connecting a plug of a connection cable in order to connect the magnetic field sensor to a tachograph.

According to another advantageous development of the invention, the surface step is a circumferential step on the inner side of the sensor element housing part. The circumferential step is preferably closed, i.e. it does not have a break. The circumferential step may be formed for example by a circumferential groove on the inner side of the sensor element housing part. lt is conceivable that the step is formed by a groove in which one groove flank is the surface step and the other groove flank forms a stop for the latching lug. ln relation to the longitudinal axis of the device housing, this stop is in particular an axial stop.

According to another advantageous development of the invention, the latching lug is a circumferential lug on the connection housing part. Such a circumferential lug does not have a break. ln this case, the latching lug may extend circumferentially on the connection housing part in a completely closed manner, whereby a particularly good sealing effect between the connection housing part and the sensor element housing part is realized, or it may, for example, also be one or more axial narrow slots or incisions, i.e. narrow slots or incisions which are aligned in the joining direction of the connection housing part and the sensor element housing part, whereby easierjoinability of the connection housing part and sensor element housing part is realized.

According to another advantageous development of the invention, the latching lug has an insertion chamfer in thejoining direction. The joining direction is the direction in which the connection housing part is installed in the sensor element housing part during the production of the magnetic field sensor. The joining direction extends preferably parallel to the longitudinal axis of the device housing, further preferably parallel to the longitudinal axis of the magnetic field sensor. The joining direction points in the direction of the pot base of the sensor element housing part. 202100583 According to another advantageous development of the invention, a contact face between the surface step and the latching lug and a parallel to a sensor longitudinal axis of the magnetic field sensor form an angle of 90° maximum, in particular precisely 90°, contrary to the joining direction of the connection housing part and the sensor element housing part. The contact face between the surface step and the latching lug is the face in which the latching lug abuts against the surface step in the fully assembled state of the magnetic field sensor, when the connection housing part and the sensor element housing part are joined together. The latching lug and surface step are therefore at a right angle to the sensor longitudinal axis, or the latching lug even engages behind the surface step in the form of a barb, that is to say if the above-described angle is smaller than 90°. lt is therefore impossible for example to pull out the connection housing part, for example at pin-shaped connection contacts of the housing part, without mechanical destruction of the connection housing part.

According to another advantageous development of the invention, a stop edge is arranged on the inner side of the sensor element housing part at a spacing, in particular at an axial spacing, from the surface step, and a radial projection, which is arranged on the connection housing part at a spacing, in particular at an axial spacing, from the latching lug, abuts against the stop edge. The spacing between the surface step and the stop edge preferably corresponds to the spacing between the latching lug and the radial projection. A particularly secure and reliable fastening of the connection housing part in the sensor element housing part is therefore guaranteed on the one hand and, on the other, it is ensured by means of the stop edge that the connection housing part is not inserted too far into the sensor element housing part when it is joined thereto.

According to another advantageous development of the invention, the connection housing part has a coding finger, which is arranged parallel to the sensor longitudinal axis and corresponds to the connection contacts. The coding finger may be arranged in particular on an inner side of the connection housing, facing the connection contacts. The coding finger may ensure for example that the connection to the connection plug is correct in terms of position and contacting.

However, the coding finger may additionally or alternatively serve to join the 202100583 7 connection housing part and the sensor housing part together in the correct position.

According to another advantageous development of the invention, the connection housing part has, at its connection housing part end which faces the second sensor element housing part end, a snap-in hook which engages in the sensor element housing part. The connection between the connection housing part and the sensor element housing part is additionally secured in an advantageous manner by means of the snap-in hook.

An exemplary embodiment of the invention is illustrated diagrammatically and schematically in the drawing and will be described in more detail below.

The drawing shows Fig. 1: a magnetic field sensor in a side view, Fig. 2: a detail of the magnetic field sensor according to figure 1 in a sectional view along line A - A in figure 1, Fig. 3: the detail according to figure 2 in a perspective sectional view, Fig. 4: the detail according to figure 2 in a perspective view, Fig. 5: a detail of a sensor element housing part of the magnetic field sensor according to figure 1 in a sectional view, Fig. 6 a connection housing part of the magnetic field sensor according to figure 1 in a side view, Fig. 7: the connection housing part according to figure 6 in a sectional view along line A - A in figure 6, Fig. 8: the connection housing part according to figure 6 in a view from below, Fig. 9: the connection housing part according to figure 6 in a view from above, Fig. 10: the connection housing part according to figure 6 in a perspective view and Fig. 11:the connection housing part according to figure 6 in a perspective sectional view. 202100583 ln all of the figures, respectively corresponding elements are provided with the same reference signs.

Figures 1, 2 show a magnetic field sensor 1 with a device housing 6 having a sensor element housing part 2 and a connection housing part 4. The magnetic field sensor 1 is formed in the shape of a rod and has a sensor longitudinal axis L, which corresponds to a longitudinal axis of the device housing 6 and also a longitudinal axis of the sensor element housing part 2 and a longitudinal axis of the connection housing part 4.

The sensor element housing part 2 is formed as a pot and is closed at a first sensor element housing part end 8 by the pot base 10 of the pot. The connection housing part 4 is arranged at the second sensor element housing part end 12 of the sensor element housing part 2.

During assembly of the magnetic field sensor 1, the connection housing part 4 and the sensor element housing part 2 are joined, wherein the connection housing part 4 is inserted into the sensor element housing part 2 in a joining direction F which is parallel to the sensor longitudinal axis L. ln the magnetic field sensor 1, i.e. in the assembled state of the magnetic field sensor 1, the connection housing part 4 closes the sensor element housing part 2. ln this case, the connection housing part 4 is arranged completely within the sensor element housing part 2. Furthermore, in the exemplary embodiment shown here, the connection housing part 4 is at a spacing from an end-face edge 14 of the sensor element housing part 2, which edge is opposite the pot base 10 of the sensor element housing part 2, the spacing being such that the outer edge 14, which is arranged at the second sensor element housing part end 12, and the connection housing part 4 have a spacing a of greater than 0 mm in the direction of the sensor longitudinal axis L.

The connection housing part 4 and the sensor element housing part 2 are connected to one another by means of a latching connection 16. The latching connection 16 has a surface step 18 on the inner side 20 of the sensor element 202100583 9 housing part 2 (c.f. figure 5) and a Iatching lug 22 (c.f. figure 7) on the connection housing part 4, which Iatching lug engages behind the surface step 18.

The sensor element housing part 2 has, on its outer side, a mechanical connection element 24 at the second sensor element housing side end 12 (see also figure 4). The connection element 24 is an integral part of the sensor element housing part 2; it is formed in one piece with the sensor element housing part 2. ln the exemplary embodiment shown here, the connection element 24 has a bayonet coupling contour 26. The mechanical connection element 24 and the connection housing part 4 form a plug connector for connection to a connection cable (not illustrated here) by means of which the magnetic field sensor 1 may be connected by way of example to a tachograph of a motor vehicle.

The connection housing part 4 has a plurality of electrical connection contacts 30 on its outer side 28. ln the exemplary embodiment shown here, the connection housing part 4 has four such connection contacts 30 (c.f. figures 9, 10). The connection contacts 30 are arranged parallel to the sensor longitudinal axis L.

The connection contacts 30 are guided through a plug base 32 of the connection housing part 4 into the interior of the device housing 4. There, contact tabs 34 (c.f. also figure 8) of the connection contacts 30 contact a printed circuit board 36. The printed circuit board 36 extends in the direction of the sensor longitudinal axis L within the device housing 6. ln the region of a sensor head 38 of the magnetic field sensor 1, a sensor element (not illustrated here) within the sensor element housing part 2 is located on the printed circuit board 36 in the vicinity of the pot base 10. The sensor element may be for example a Hall element. The sensor head 38 comprises the second sensor element housing part end 12 and has the pot base 10.

The surface step 18 is a circumferential step on the inner side 20 of the sensor element housing part 2. ln the exemplary embodiment shown here, the surface step 18 is a closed circumferential step, which has no break. The surface step 18 is formed by a circumferential groove 40 on the inner side 20 of the sensor element housing part 2, wherein a first groove flank 42 of the groove 40 forms the 202100583 surface step 18. The second groove flank 44 may serve for example as a stop for the latching lug 22 of the connection housing part 4. However, the second groove flank 44 preferably has an at least slight spacing from the latching lug 22 in order to ensure a secure latching-in of the latching lug 22 and therefore a reliable latching connection 16.

As shown by figures 10, 11, for example, the latching lug 22 is a circumferential lug on the connection housing part 4. ln the exemplary embodiment shown here, the latching lug 22 extends circumferentially on the connection housing part 4 in a closed manner. However, it is fundamentally also conceivable for example that the latching lug 22 has one or more axial slots, i.e. slots which extend in the joining direction F.

The latching lug 22 has an insertion chamfer 46 in thejoining direction F. A contact face between the surface step 18 and the latching lug 22 on the one hand and a parallel to the sensor longitudinal axis L of the magnetic field sensor 1 on the other form an angle of 90° maximum, namely precisely 90° in the exemplary embodiment shown here, contrary to the joining direction F (c.f. figure 2).

A stop edge 48 is arranged on the inner side 20 of the sensor element housing part 2, at a spacing from the surface step 18 (c.f. figure 5). A radial projection 50, which is arranged on the connection housing part 4, at a spacing from the latching lug 22, abuts against the stop edge 48 (see figures 2, 11).

The connection housing part 4 has a coding finger 52, which is arranged parallel to the sensor longitudinal axis L. As illustrated for example in figure 10, the connection housing part 4 in the exemplary embodiment shown here has a total of four such coding fingers 52, 52', 52", 52"".

Figures 2, 3 show that the connection housing part 4 and the sensor element housing part 2 are also connected by means of a snap-in connection 54 in addition to the latching connection 16. For this snap-in connection 54, the connection housing part 4 has, at its connection housing part end 56 which faces the second sensor element housing part end 12 (c.f. figure 6), a snap-in hook 58 which 202100583 1 1 engages in the sensor element housing part 2. The snap-in hook 58 is formed annularly on the connection housing part end 56.

Claims

1. Claims A magnetic field sensor (1) with a device housing (6) having a sensor element housing part (2) and a connection housing part (4), wherein the sensor element housing part (2) is formed as a pot and is closed at a first sensor element housing part end (8) by the pot base (10) of the pot and wherein the connection housing part (4) is arranged at the second sensor element housing partend(12), characterized in that the connection housing part (4) closes the sensor element housing part (2) and is arranged completely within the sensor element housing part (2) and in that the connection housing part (4) and the sensor element housing part (2) are connected to one another by means of a latching connection (16), wherein the latching connection (16) has a surface step (18) on the inner side (20) of the sensor element housing part (2) and a latching lug (22) on the connection housing part (4), which latching lug engages behind the surface step (18)The magnetic field sensor as claimed in claim 1, c h a r a c t e r i z e d in th a t the sensor element housing part (2) has, on its outer side, a mechanical connection element (24) at the second sensor element housing part end (12)The magnetic field sensor as claimed in claim 1 or 2, c h a r a c t e r i z e d in th at the connection housing part (4) has at least two electrical connection contacts (30) on its outer side (28)The magnetic field sensor as claimed in one of the preceding claims, c h a r a c t e r i z e d in th at the surface step (18) is a circumferential step on the inner side (20) of the sensor element housing part (2)The magnetic field sensor as claimed in one of the preceding claims, c h a r a c t e r i z e d in th a t the latching lug (22) is a circumferential lug on the connection housing part (4)The magnetic field sensor as claimed in one of the preceding claims,characterized in thatthelatchinglug(22)hasaninsertion chamfer (46) in thejoining direction (F)The magnetic field sensor as claimed in one of the preceding claims, c h a r a cte r i z e d in th at a contact face between the surface step (18) and the latching lug (22) and a parallel to a sensor longitudinal axis (L) of the magnetic field sensor (1) form an angle of 90° maximum contrary to the joining direction (F) of the connection housing part (4) and the sensor element housing part (2)The magnetic field sensor as claimed in one of the preceding claims, characterized in that astopedge (48) isarrangedon the inner side (20) of the sensor element housing part (2), at a spacing from the surface step (18), and in that a radial projection (50), which is arranged on the connection housing part (4), at a spacing from the Iatching lug (22), abuts against the stop edge (48)The magnetic field sensor as claimed in one of the preceding claims, characterized in that theconnection housing part(4)hasa coding finger (52), which is arranged parallel to the sensor longitudinal axis (L) and corresponds to the connection contacts (30)The magnetic field sensor as claimed in one of the preceding claims, c h a r a c t e r i z e d in th a t the connection housing part (4) has, at its connection housing part end (56) which faces the second sensor element housing part end (12), a snap-in hook (58) which engages in the sensor element housing part (2).