Magnetic field sensor including a marking and method for manufacturing a magnetic field sensor

Abstract

Magnetic field sensor comprising a marking and method for manufacturing a magnetic field sensor. The invention relates to a magnetic field sensor comprising a device housing 1 having at least a first part of a housing 2 and a second part of a housing 4 closing the first part of a housing 2, the first part of a housing 2 and the second part of a housing 4 being assembled and connected by means of a non-removable joint 6. In order to increase protection of the magnetic field sensor against possible manipulation, it is proposed that an external side of the housing 8 of the device housing 1 has, in the region of the joint 6, a graphic marking 10, the first part of a housing 2 having a first part of the marking 20 and the second part of a housing 4 having a second part of the marking 22 graphically aligned with the first part of the marking 20.Figure for the abbreviation: Figure 1.

Description

Title of the invention: Magnetic field sensor comprising a marking and method for manufacturing a magnetic field sensor

[0001] The invention relates to a magnetic field sensor comprising an apparatus housing having at least a first housing part and a second housing part closing the first housing part, the first housing part and the second housing part being assembled and being connected by means of a non-removable joint connection. Furthermore, the invention relates to a method for manufacturing an aforementioned magnetic field sensor.

[0002] Such a magnetic field sensor is known, for example, as a speed sensor or rotation angle sensor for a tachograph in a motor vehicle, in particular a utility vehicle. The magnetic field sensor has a sensor head and is, for example, screwed into a transmission housing of a transmission of the motor vehicle or is, for example, fastened in the vicinity of a rotating component rotating in a manner corresponding to a driving speed of the motor vehicle. The magnetic field sensor detects, by means of the sensor head, a displacement of a transmission gear wheel of the transmission or the rotating component. The displacement of the transmission gear wheel is a measure of the speed of the motor vehicle. A part of a first housing part of a device housing of the magnetic field sensor is part of the sensor head.

[0003] The first housing part is closed by a second housing part of the device housing, the second housing part having connection contacts by means of which the magnetic field sensor is connected to the tachograph of the motor vehicle. In order to protect the components of the magnetic field sensor arranged in the device housing both against environmental influences and against unauthorized external interventions, the first housing part and the second housing part are connected by means of a non-removable joint connection. Since the data recorded with the tachograph must be extremely reliable, it is also important to avoid manipulation of the magnetic field sensor and data errors resulting from such manipulation.

[0004] The object of the invention is to provide a magnetic field sensor of the type mentioned in the introduction, which has a high degree of protection against manipulation. Furthermore, the object of the invention is to indicate a manufacturing method of a magnetic field sensor with high protection against manipulation.

[0005] The first-mentioned object is achieved according to the invention by the fact that an outer housing side of the device housing has, in the region of the joint connection, a graphic marking, the first housing part having a first marking part of the marking and the second housing part having a second marking part of the marking graphically adjusted to the first marking part, and the two marking parts extending into each other homogeneously.

[0006] In the case of the magnetic field sensor according to the invention, it is particularly advantageous to have a homogeneous transition of the two marking parts of the first housing part and the second housing part. The two marking parts are graphically adjusted to one another and thus produce, for example, an image or, for example, a linear structure or, for example, a pattern or, for example, a decoration. The marking extends beyond a boundary area, for example, a dividing line between the first housing part and the second housing part.

[0007] The marking may have several marking segments extending beyond the boundary area between the first housing part and the second housing part. These marking segments thus each have a corresponding first marking part mentioned above and a corresponding second marking part mentioned above, the first and second marking parts, i.e. each marking segment, being graphically adjusted to one another and extending into one another homogeneously.

[0008] The fact that the outer housing side of the device housing has the graphic marking in the region of the joint connection means that the graphic marking is located in the joint connection or that it is arranged in the immediate vicinity of the joint connection or that it is arranged parallel to the joint connection and in this case at the height of the joint connection.

[0009] If the device housing, for the purpose of manipulation, for example to replace a printed circuit board of the magnetic field sensor arranged in the device housing, is separated, for example, at a separation line between the first housing part and the second housing part by means of a thin saw blade and is then reassembled again after removing and replacing the printed circuit board, an at least minimal offset is created between the first marking part and the second marking part. The first marking part and the second marking part therefore no longer extend homogeneously into each other, the marking is visibly destroyed in a manner that can be detected optically, for example by means of a magnifying glass. The manipulation carried out therefore remains visible from permanently. For example, opening the device housing by sawing, for example by means of a thin saw cut, is therefore not possible without leaving permanently visible changes to the device housing. Thus, the invention provides reliable protection against manipulation.

[0010] For example, it is possible to envisage applying the marking by means of a coating process to the first housing part and the second housing part. Such a coating process may, for example, include hot stamping, pad printing, screen printing or inkjet printing. On the other hand, to facilitate the production of the marking and to obtain particularly good resistance of the marking, it is particularly advantageous for the marking, according to an improvement of the invention, to be marked in the first housing part and in the second housing part by a laser process. In such a laser process, no dye is applied to the device housing, but, for example, material is removed or, for example, a chemical transformation of the material is carried out at the surface of the device housing.The material removal or transformation can preferably be combined with a color change so that it is even more difficult to conceal manipulation. Advantageously, it is also not possible to remove the graphic marking applied by means of the laser process, for example using solvents, and to reapply it after manipulation of the device housing.

[0011] According to a further advantageous improvement of the invention, the marking has at least one first line extending at a first acute angle over a dividing line between the first housing part and the second housing part. This line thus extends obliquely over the dividing line between the first housing part and the second housing part. As a result, a line shift after separation and reassembly of the device housing is particularly visible at the dividing line and can therefore be detected even more easily.

[0012] Such detection is further improved and therefore the protection against manipulation is further increased if, according to an advantageous improvement of the invention, the marking has a second line extending at a second acute angle over the separation line between the first housing part and the second housing part, the second acute angle being different from the first acute angle.

[0013] According to a further advantageous improvement of the invention, the marking extends over the major part of the periphery of the appliance housing. The marking thus extends over more than half of the periphery of the appliance housing. In this way, a marking is obtained over a particularly large surface within which the possible destruction can be recognized very easily, further improving protection against manipulation.

[0014] According to another advantageous improvement of the invention, the marking has a two-dimensional code. The two-dimensional code extends beyond the dividing line between the first housing part and the second housing part. The two-dimensional code may in particular be an optically readable code. Preferably, the two-dimensional code is a Data Matrix Code (DMC). If such a two-dimensional code is cut and subsequently reassembled during a manipulation to open the appliance housing, the code will be missing some pixels, or even entire rows of data, so that reading the code is no longer possible without difficulty. The graphic marking may have one or more two-dimensional codes of this type.The two-dimensional code can, for example, present individual data information with which the magnetic field sensor is individualized, so that the magnetic field sensor can be uniquely identified using the two-dimensional code.

[0015] A further increase in security and protection against manipulation can be advantageously achieved according to an improvement of the invention, when the magnetic field sensor has a data memory and the two-dimensional code, in particular the data matrix code, has data information which coincides with the data information stored in the data memory. In this way, a simple comparison of the data information of the two-dimensional code with the data information stored in the data memory can reveal manipulation of the housing of the magnetic field sensor.

[0016] It could, for example, be envisaged that the device housing is a metal housing or that, for example, one of the two housing parts is a metal component and the other housing part is a plastic component. On the other hand, to facilitate the manufacture of the magnetic field sensor and reduce its cost, it is particularly advantageous, according to a further improvement of the invention, for the first housing part and the second housing part to each consist of a preferably identical plastic material. The first housing part and the second housing part are in this case each a plastic component. Preferably, the plastic material of the first housing part and / or the second housing part has glass fibers to increase the strength, for example in a proportion of 30%.

[0017] For example, one could consider that the joint connection is an adhesive connection. On the other hand, to obtain a joint connection that is particularly reliable, durable and in particular can also be easily manufactured in large series, it is advantageously according to an improvement of the invention, that the joint connection is a pressure welding connection. Preferably, the pressure welding connection may be an ultrasonic welding connection.

[0018] The second mentioned object is achieved according to the invention with a method for manufacturing a magnetic field sensor, a first housing part and a second housing part of a device housing of the magnetic field sensor being assembled and being connected by means of a non-removable joint connection. The method is further characterized in that an outer housing side of the device housing is provided with a graphic marking, the first housing part is provided with a first marking part of the marking and the second housing part is provided with a second marking part of the marking, and this in such a way that the first marking part and the second marking part are graphically adjusted to one another and the two marking parts extend into one another homogeneously.The method according to the invention is particularly suitable for the production of a magnetic field sensor according to the invention. The first housing part and the second housing part are preferably pressure welded, in particular ultrasonically welded.

[0019] For example, it is possible to envisage that the outer side of the housing is provided with a graphic marking by applying the marking to the outer side of the housing by means of a coating process. However, it is particularly advantageous if the outer side of the housing is provided with the marking by means of a laser process. In this case, the marking is applied in the device housing at its outer housing side. For example, material removal or, for example, chemical transformation of the material is carried out at the surface of the device housing.

[0020] For example, it could be envisaged, in a single process step, to apply the marking to the outer side of the housing over the majority of the periphery, in particular also over the entire periphery of the device housing. For precise and economical production of the magnetic field sensor, on the other hand, it is advantageous if the outer side of the housing is provided with the marking on a portion of a periphery of the device housing. The portion of the periphery of the device housing is preferably less than half of the periphery of the device housing.

[0021] Advantageously, according to a relatively simple and economical method, the outer side of the housing can be provided with a large marking, thus offering increased protection against manipulation, by first providing the outer side of the housing with a first marking segment of the marking extending over a first portion of the periphery of the device housing, and then rotating the magnetic field sensor through an angle about a longitudinal axis of the device housing, for example in the counterclockwise direction and then providing the outer side of the housing with a second marking segment of the marking extending over a second portion of the periphery of the device housing. Preferably, the first and second marking segments are located next to each other on the periphery of the device housing.

[0022] It is particularly advantageous if the magnetic field sensor is additionally rotated about a second determined angle about the longitudinal axis of the housing of the device, for example counterclockwise, and the outer side of the housing is then provided with a third marking segment of the marking extending over a third portion of the periphery of the device housing. Thus, at least almost the entire periphery of the device housing can be provided with the marking in a simple manner. Preferably, the second and third marking segments are located next to each other on the periphery of the device housing.

[0023] The invention also includes improvements to the method according to the invention which have characteristics as already described in connection with the improvements to the magnetic field sensor according to the invention, and vice versa. For this reason, the corresponding improvements to the method according to the invention have not yet been described here.

[0024] The invention also includes combinations of features of the described embodiments.

[0025] Exemplary embodiments of the invention will be described in more detail below with the aid of the schematic illustrations and in the form of diagrams in the drawings. In the drawings:

[0026] [Fig. 1] [Fig. 1] illustrates a portion of a device housing of a magnetic field sensor in perspective view,

[0027] [Fig.2] [Fig.2] illustrates a portion of a graphic marking of the apparatus housing of [Fig.l],

[0028] [Fig.3] [Fig.3] illustrates a top view of the apparatus housing of [Fig.l],

[0029] [Fig.4] [Fig.4] illustrates a first side view of the apparatus housing of [Fig.l],

[0030] [Fig.5] [Fig.5] illustrates a second side view of the apparatus housing of the [Fig.l], and

[0031] [Fig.6] [Fig.6] illustrates a third side view of the apparatus housing of [Fig.l].

[0032] The corresponding elements are all provided with the same reference numbers in all the figures.

[0033] [Fig. 1] illustrates, in a perspective side view, a part of a device housing 1 of a magnetic field sensor. The device housing 1 has a first housing part 2, which is designed as a housing pot (see [Fig. 4]), and a second housing part 4 closing the first housing part 2, which is designed as a housing cover. In this exemplary embodiment, the first housing part 2 and the second housing part 4 together form the device housing 1.

[0034] Both the first housing part 2 and the second housing part 4 are composed, in this exemplary embodiment, of a plastic material and preferably are an injection-molded plastic component. Glass fibers may be added to the plastic material of the first housing part 2 and the second housing part 4 to increase strength.

[0035] The first housing part 2 and the second housing part 4 are joined and assembled by means of a non-removable joint connection 6. In the embodiment shown here, the first housing part 2 and the second housing part 4 are joined in the direction of a longitudinal axis L of the device housing 1. Furthermore, the joint connection 6 is here a pressure welding connection. Preferably, the pressure welding connection may be an ultrasonic welding connection.

[0036] An outer housing side 8 of the device housing 1 of the magnetic field sensor has, in the region of the joint connection 6, a graphic marking 10. The graphic marking 10 has here a first marking segment 16, a second marking segment 14 and a third marking segment 12, which marking segments 12, 14, 16 each have a linear pattern. In addition, the graphic marking 10 has here a fourth additional marking segment 18 which has a two-dimensional code (see [Fig. 6]). The two-dimensional code can in particular be a Data Matrix Code (DMC).

[0037] The first housing part 2 of the device housing 1 has a first marking part 20 of the marking 10 and the second housing part 4 has a second marking part 22 of the marking 10 graphically adjusted to the first marking part 20. The two marking parts 20, 22 extend into each other homogeneously. This shows, for example, that the linear patterns of the three first-mentioned marking segments 12, 14, 16 are not destroyed when passing over a dividing line 24 between the first housing part 2 and the second housing part 4. The marking 10 extends beyond the dividing line 24.

[0038] By "extend homogeneously" is meant here in particular an extension of the two marking parts 20, 22 into each other without a step, i.e. a transition between the two marking parts 20, 22 without a step.

[0039] The four aforementioned marking segments 12, 14, 16, 18 each have a first marking portion 20 described above, which the first housing part 2 has, and each have a second marking portion 22 described above, which the second housing part 4 has. The respective first and second marking portions 20, 22 each extend beyond the separation line 24, are at each time graphically adjusted to each other and each time extending homogeneously into each other (see figures 4 to 6).

[0040] In a first exemplary embodiment, the marking 10 can, for example, be applied by means of a coating process to the outer housing side 8 of the device housing 1. In the exemplary embodiment illustrated here, the marking 10 is, on the other hand, marked in the first housing part 2 and in the second housing part 4 by means of a laser process on the outer housing side 8 of the device housing 1.

[0041] The embodiment of the marking 10 will be explained in more detail below with the aid of [Fig. 2]. [Fig. 2] illustrates by way of example the second marking segment 14 of the graphic marking 10 of the apparatus housing of [Fig. 1]. The second marking segment 14 has a linear pattern, and it can be seen that the marking 10 has a first line 26 extending at a first acute angle α over the dividing line 24 between the first housing part 2 and the second housing part 4. Furthermore, it can be seen that the marking 10 has a second line 28 extending at a second acute angle α over the dividing line 24 between the first housing part 2 and the second housing part 4, the second acute angle α being different from the first acute angle α. In this exemplary embodiment, the second acute angle α is greater than the first acute angle α.The first acute angle a is the angle between the dividing line 24 and the first line 26, and the second acute angle [3 is the angle between the dividing line 24 and the second line 28. For example, when separating the device housing 1, there also occurs at the dividing line 24, after reassembly of the first housing part 2 and the second housing part 4, an optically visible shift of the lines in the linear pattern of the first three marking segments 12, 14, 16.

[0042] [Fig. 3] illustrates a top view of the device housing of [Fig. 1]. It can be seen that the device housing 1 of the magnetic field sensor, in this exemplary embodiment, furthermore has, at the first housing part 2 (see [Fig. 6]), a cable inlet 30. The cable inlet 30 serves for the electrical connection of electronic components of the magnetic field sensor, arranged in the device housing 1, for example to a tachograph of a motor vehicle. For example, a connection cable to the tachograph is introduced through the cable inlet 30 into the device housing and is electrically connected to a printed circuit board arranged in the device housing 1.

[0043] The printed circuit board carries a sensor element, for example a Hall effect element. The sensor element with possibly an associated magnet, arranged on the printed circuit board, is arranged in a sensor head 32 of the magnetic field sensor, which magnetic field sensor can also be called an inductive sensor. A part of the first housing part 2 of the device housing 1, namely in this case a pot-shaped end portion of the first housing part 2, is part of the sensor head 32 (see [Fig. 6]). Furthermore, the first housing part 2 has a connecting element 34 for attaching the magnetic field sensor, for example to a motor vehicle. The connecting element 34 has, for example, a half-width b of approximately 15 mm.

[0044] In an exemplary embodiment, the printed circuit board not shown here, arranged in the device housing 1, has a data memory. The data memory has data information which is data information stored in the data memory and which coincides with data information which is presented by the two-dimensional code provided by the fourth marking segment 18.

[0045] A first side view of the appliance housing 1 from the direction A according to [Fig. 3], this direction A and the connecting element 34 forming for example an angle yl of approximately 60°, is illustrated in [Fig. 4]. A second side view of the appliance housing 1 from the direction B according to [Fig. 3], this direction B and said direction A forming for example an angle y 2 of approximately 90°, and this direction B and a median axis of the connecting element 34 forming for example an angle y4 of approximately 30°, is illustrated in [Fig. 5], and a third side view from the direction C according to [Fig. 3], this direction C and said direction B forming for example an angle y 3 of approximately 90°, is illustrated in [Fig. 6].

[0046] A height h of the marking 10 as well as of the four marking segments 12, 14, 16, 18 measures for example approximately 8 mm. The third marking segment 12 and the fourth marking segment 18 together have for example a length 11 of approximately 25 mm. The second marking segment 14 has for example a length 12 of approximately 17 mm. The first marking segment 16 has for example a length 13 of approximately 28 mm. It can be seen in Figures 4, 5, and 6 that the marking 10 extends over the majority of the periphery, namely over more than half of the periphery of the device housing 1.

[0047] In the case of a manufacture of the magnetic field sensor, the outer side of the housing 8 can, in an exemplary embodiment, first be provided with the first marking segment 16 of the marking 10 extending over a first portion of the periphery of the device housing 1, then the magnetic field sensor can be rotated through an angle y 2 of approximately 90° around the longitudinal axis L of the device housing 1 in an anticlockwise direction, then the outer side of the housing 8 can be provided with the second marking segment 14 of the marking 10 extending over a second part of the periphery of the device housing 1. Then, the magnetic field sensor can be rotated through a second angle y 3 of approximately 90° around the longitudinal axis L of the device housing 1 in an anticlockwise direction and then the outer side of the housing 8 can be provided with a third marking segment 12 extending over a third portion of the periphery of the device housing 1, which may optionally be supplemented with a fourth marking segment 18 of the marking 10, which may also extend into the third portion of the part of the periphery of the device housing 1.

[0048] By means of a corresponding division of the marking 10 into the three marking segments 16, 14, 12, a simplified manufacture of the magnetic field sensor can be achieved. Referring to Figures 3 to 6, in the embodiment shown here, the first marking segment 16 is thus, for example, first introduced into the device housing 1 from direction A. Then, the magnetic field sensor is rotated through 90° (angle y2) about the longitudinal axis L of the device housing 1 in a counterclockwise direction, and this is followed by the introduction from direction B (with respect to the region of the corresponding housing exterior 8 to be provided with the additional marking segment) of the second marking segment 14 into the device housing 1. Then, the magnetic field sensor is further rotated through 90° (angle y3) about the longitudinal axis L of the device housing 1 in a counterclockwise direction.Finally, the third marking segment 12 is introduced together with the fourth marking segment 18 into the device housing 1, from the direction C (relative to the region of the corresponding housing outer side 8, to be provided with the additional marking segments).

[0049] Thus, the first marking segment 16, the second marking segment 14 and the third marking segment 12 (together with the fourth marking segment 14) each separately form a closed unit. However, introduced into the device housing 1 in three separate, preferably successive, process steps, they together form the graphic marking 10. This represents a potential simplification of the manufacture of the magnetic field sensor, in particular a possibility of reducing costs while simultaneously increasing process reliability compared to an introduction of the marking 10 into the device housing 1 in a single process step.

[0050] By means of the invention, the objective of preventing undetectable opening of the appliance housing 1 can be advantageously achieved. For example, in the case of a separation of the appliance housing 1 at the separation line 24 by means of a narrow, flat cut (with a saw) and consequently a separation of the first housing part 2 from the second housing part 4, the marking 10 is damaged in such a way that the linear patterns illustrated in the three marking segments 12, 14, 16, during a subsequent reassembly of the first housing part 2 and the second housing part 4, have an offset at the separation line 24. The two-dimensional code illustrated in the fourth marking segment 18 is furthermore damaged during separation to such an extent that in the event of subsequent reassembly, the data information of the two-dimensional code is damaged and / or missing. A manipulation attempt to open the device housing of the magnetic field sensor is therefore easy to detect optically both, for example, by means of a magnifying glass and by reading the data information of the two-dimensional code.

Claims

Claims

1. Magnetic field sensor comprising a device housing (1) having at least a first housing part (2) and a second housing part (4) closing the first housing part (2), the first housing part (2) and the second housing part (4) being assembled and being connected by means of a non-removable butt joint (6), wherein a housing outer side (8) of the device housing (1) has, in the region of the butt joint (6), a graphic marking (10), the first housing part (2) having a first marking part (20) of the marking (10) and the second housing part (4) having a second marking part (22) of the marking (10) graphically adjusted to the first marking part (20), and the two marking parts (20, 22) extend seamlessly into one another,characterized in that the marking (10) is marked in the first housing part (2) and in the second housing part (4) by means of a laser process.,

2. Magnetic field sensor according to claim 1, characterized in that the marking (10) has at least one first line (26) extending at a first acute angle (a) over a dividing line (24) between the first housing part (2) and the second housing part (4).

3. Magnetic field sensor according to claim 2, characterized in that the marking (10) has at least one second line (28) extending at a second acute angle (|3) over the dividing line (24) between the first housing part (2) and the second housing part (4), the second acute angle (|3) being different from the first acute angle (a).

4. Magnetic field sensor according to any one of the preceding claims, characterized in that the marking (10) extends over the major part of the periphery of the device housing (1).

5. Magnetic field sensor according to any one of the preceding claims, characterized in that the marking (10) has a two-dimensional code.

6. Magnetic field sensor according to claim 5, characterized in that the magnetic field sensor has a data memory and in that the two-dimensional code has data information that matches the data information recorded in the data memory.

7. Magnetic field sensor according to any one of the preceding claims, characterized in that the first housing part (2) and the second housing part (4) each consist of a plastic material.

8. Magnetic field sensor according to any one of the preceding claims, characterized in that the joint connection (6) is a pressure welding connection.

9. A method for manufacturing a magnetic field sensor, in particular a magnetic field sensor according to any one of the preceding claims, wherein a first housing part (2) and a second housing part (4) of an apparatus housing (1) of the magnetic field sensor are assembled and are connected by means of a non-removable butt joint (6), wherein a housing outer side (8) of the apparatus housing (1) is provided with a graphic marking (10) in such a way that the first housing part (2) is provided with a first marking part (20) of the marking (10) and the second housing part (4) is provided with a second marking part (22) of the marking (10), and this in such a way that the first marking part (20) and the second marking part (22) are graphically adjusted to each other and that the two marking parts (20, 22) extend into each other. the other in a homogeneous manner,characterized in that the marking (10) is marked in the first housing part (2) and in the second housing part (4) by means of a laser process.,

10. Method according to claim 9, characterized in that the outer side of the housing (8) is provided with the marking (10) on a portion of a periphery of the apparatus housing (1).

11. Method according to any one of claims 9 to 10, characterized in that the outer side of the housing (8) is first provided with a first marking segment (16) of the marking (10) extending over a first portion of the periphery of the device housing (1), then the magnetic field sensor is rotated through a determined angle (y2) around a longitudinal axis (L) of the device housing (1) in an anticlockwise direction, then the outer side of the housing (8) is provided with a second marking segment (14) of the marking 14 (10) extending over a second part of the periphery of the apparatus housing (1).

12. The method according to claim 11, characterized in that the magnetic field sensor is rotated about a second determined angle (y3) about the longitudinal axis (L) of the device housing (1) and in that the outer side of the housing (8) is then provided with a third marking segment (12) of the marking (10) extending over a third portion of the periphery of the device housing (1).

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