Sensor unit with rigid and elastic positioning means

Abstract

The present invention relates to a sensor unit, comprising a circuit board with capture means and at least one fixing element, a carrier unit, comprising a fixing portion, and a support portion for receiving and orienting the circuit board, and rigid and elastic positioning means, wherein the rigid positioning means are effectively connected to the fixing element of the circuit board and to the fixing portion of the carrier unit in such a manner that the circuit board is rigidly connected to the carrier unit in the region of the fixing element and the elastic positioning means press the circuit board onto the support portion in such a manner that the circuit board is connected movably relative to the support portion of the carrier unit in order to compensate thermally induced mechanical tensions.

Description

[0001] Sensor unit with rigid and elastic positioning means

[0002] The present invention relates to a sensor unit according to claim 1.

[0003] Sensor units comprising a circuit board with detection means for detecting objects and / or physical quantities are generally known from the prior art.

[0004] In practice, a permissible temperature range must be considered when using sensor units. Within this permissible temperature range, the manufacturer must guarantee the unrestricted functionality of the sensor unit. In addition to the sensor unit's characteristic properties, such as measurement accuracy and / or acquisition speed, the thermal design of the sensor unit is therefore also crucial.

[0005] During thermal design, the different thermal expansion coefficients of critical components, such as a circuit board for accommodating and electrically connecting the detection means as well as the corresponding carrier unit of the sensor unit, which mechanically holds the circuit board, must be taken into account in such a way that they do not have a negative impact on the measurement result of the sensor unit.

[0006] In this context, various solutions are known from the state of the art.

[0007] On the one hand, it is common practice to select critical components from special materials with low or, in the case of materials that interact, similar thermal expansion coefficients. In practice, this is usually not feasible or results in high material costs, even though the manufacturer only permits the use of the sensor unit for a narrow temperature range.

[0008] Furthermore, it is also known from the prior art that the influence of a temperature change on the measurement result is compensated by means of auxiliary electronics. Such auxiliary electronics directly or indirectly determine the temperature in order to determine a correction value depending on this temperature. Such a solution is not only complex and therefore costly, but can also lead to a falsification of the measurement result of the sensor unit. Therefore, the present invention is based on the object of overcoming the disadvantages known from the prior art.In particular, it is the object of the present invention to provide a sensor unit with a circuit board, wherein the circuit board can be fixed to a carrier unit for positioning and / or aligning the detection center of the circuit board in such a way that a different thermal expansion between the circuit board and the carrier unit does not have a negative effect on the detection means and thus on the measurement result of the sensor unit.

[0009] This object is achieved by a device according to the invention according to claim 1.

[0010] Advantageous further developments of the invention are described in the subclaims. The scope of the invention includes all combinations of at least two of the features disclosed in the description, the claims, and / or the figures.

[0011] The present invention relates to a sensor unit comprising a circuit board with detection means and at least one fixing element.

[0012] The sensor unit according to the invention comprises a carrier unit for receiving and aligning the circuit board. The carrier unit has a fixing section and a support section. The support section preferably comprises a support surface with which the circuit board is in contact for alignment and / or positioning.

[0013] Furthermore, the sensor unit according to the invention comprises rigid positioning means and elastic positioning means.

[0014] The rigid positioning means are in operative contact with the fixing element of the circuit board on the one hand and with the fixing section of the carrier unit on the other hand in order to rigidly connect the circuit board to the carrier unit.

[0015] In other words, the rigid positioning means realize a positive and / or non-positive connection between the circuit board and the carrier unit, which is why a rigid coupling between the circuit board and the carrier unit occurs in the area of ​​the rigid positioning means and / or around the rigid positioning means.

[0016] The elastic positioning means are in operative contact with the circuit board in such a way that the circuit board is pressed onto the support section of the carrier unit with a specific force. The pressing force acting on the circuit board, which is directed transversely to the plane of extension of the circuit board, presses the circuit board onto the support section of the carrier unit. In the event of a temperature change, the circuit board and the carrier unit can therefore expand independently of one another. A relative movement between the circuit board and the carrier unit is thus deliberately permitted to compensate for thermally induced stresses, whereby such expansion does not have a negative effect on the detection means. Since the circuit board and the carrier unit are rigidly connected to one another via the fixing element and the fixing section as well as the rigid positioning means, such a relative movement will have an effect starting from this area.

[0017] The elastic positioning means and the support section interact in such a way that a relative movement between the circuit board and the carrier unit is permitted, transverse to the force introduced into the circuit board by means of the elastic positioning means. This movable and / or elastic connection between the circuit board and the carrier unit allows the circuit board to expand and / or contract independently of the carrier unit, particularly within its plane of extension. This advantageously prevents thermally induced mechanical stresses between the carrier unit and the circuit board, so that they cannot affect the measurement result of the sensor unit and / or only to a permissible extent, while simultaneously enabling alignment of the circuit board.

[0018] The force required in this context for pressing the circuit board onto the support section of the carrier unit is in particular in a range between 50N to 1000N, preferably 150N to 600N, particularly preferably 154N to 594N.

[0019] According to the invention, the circuit board, which comprises the detection means sensitive to thermally induced mechanical stresses, is thus rigidly connected to the carrier unit only by the rigid positioning means, so that the circuit board can expand in the longitudinal and transverse directions relative to the carrier unit starting from the fixing element.

[0020] In the support section, in which the circuit board is also in contact with the carrier unit, the alignment of the circuit board relative to the carrier unit takes place in a plane, in particular within the extension plane of the circuit board in which the circuit board is essentially formed.

[0021] The elastic positioning means, which press the circuit board against the support section of the carrier unit, generate a force that runs essentially transversely to the plane of extension of the circuit board and is dimensioned such that the circuit board can expand transversely to a support surface of the support section and / or transversely to the applied force to compensate for thermally induced mechanical stresses. The circuit board can thus advantageously slide along the support section, in particular along the support surface, which is why the relative position between the circuit board and the carrier unit can change here. Advantageously, the circuit board can thus expand around the fixing element almost arbitrarily within the plane of extension.

[0022] In a further development, the fixing element is designed as a recess, in particular as a bore. This advantageously allows the fixing element to be implemented cost-effectively within the circuit board, enabling the circuit board to be fixed in all directions. The recess is preferably closed around its circumference and designed as a hole and / or opening in the circuit board.

[0023] In a preferred embodiment of the sensor unit according to the invention, the rigid positioning means are designed as a form-fitting connection element, preferably as a bolt and / or a retaining pin and / or a screw. The rigid positioning means can thus advantageously be realized using standardized components, which enables low material costs. A form-fitting connection element and / or a screw also interacts optimally with a recess, in particular a bore.

[0024] In a further development, the elastic positioning means are round and / or circular and / or annular, in particular as an O-ring or damping ring or buffer ring. In other words, the elastic positioning means comprise an O-ring or buffer ring to generate the force that presses the circuit board onto the support section, in particular the support surface. The O-ring or damping ring or buffer ring is subjected to force and thus deformed. Additionally or alternatively, it is also provided in a further development that the support section is round and / or circular and / or annular. This advantageously enables large-area and / or uniform positioning and / or alignment of the circuit board.

[0025] In this context, it is particularly preferred if the fixing section is arranged within the annular support section, preferably centrally to the support section.

[0026] In other words, in this context, it is planned that the annular support section, which is formed in particular by one or more annular surfaces and one or more partial circular surface pieces, delimits and / or defines an area within which the fixing section is positioned. Thus, thermally induced mechanical stresses in the carrier unit and / or the circuit board can expand around the fixing section in all directions, in particular in all longitudinal and transverse directions.

[0027] Furthermore, in a further preferred embodiment, it is planned that the board comprises at least one notch on the edge side, which preferably extends on the outside along a partial section, in particular a partial circle section.

[0028] The notch advantageously simplifies the assembly of the sensor unit, as the alignment of the circuit board to the carrier unit can be symbolically represented. This advantageously simplifies the production of the sensor unit, as the arrangement of the circuit board to the carrier unit can be specified and / or graphically signaled to the assembly operator.

[0029] In a further development, it is preferably provided that the carrier unit is designed as a housing underside of the sensor unit, in particular the housing underside of an inclination sensor. It is also advantageously provided that the carrier unit is aligned relative to an external object via the housing underside, in order to detect, for example, a temperature and / or position and / or force and / or angle of the external object.

[0030] In a further development, it is provided that the sensor unit comprises a housing top side, wherein in a closed state of the sensor unit the housing top side can be fixed on the housing bottom side in such a way that the elastic positioning means are deformed in order to apply a force which presses the circuit board onto the support section.

[0031] Furthermore, within the scope of the present invention, an embodiment of the sensor unit is particularly preferred in which the sensor unit is designed as an inclination sensor and the detection means are designed as inclination detection means.

[0032] The invention is explained in more detail below by way of example with reference to the drawings. The combination of features presented as examples in the embodiments shown can be supplemented by further features in accordance with the above explanations, depending on the properties required for a specific application. Individual features can also be omitted from the described embodiments if the effect of this feature is not important in a specific application.

[0033] In the drawings, elements with the same function and / or structure are designated by the same reference numerals. They show:

[0034] Fig. 1: an exploded view of a sensor unit according to the invention according to an embodiment;

[0035] Fig. 2: a perspective view of the already known sensor unit according to the embodiment

[0036] Fig. 3: a schematic sectional view of the known sensor unit according to the embodiment and

[0037] Fig. 4: a further schematic sectional view of the sensor unit according to the invention according to a further embodiment.

[0038] Fig. 1 shows an exploded view of a sensor unit 1 according to the invention with detection means 3 according to a preferred embodiment.

[0039] In the illustrated embodiment, the sensor unit 1 according to the invention is designed as an inclination sensor 100.

[0040] The inclination sensor 100 according to the invention comprises inclination detection means 103, which are mechanically held and electrically connected on a circuit board 2.

[0041] Furthermore, the circuit board 2 comprises at least one fixing element 4, which is designed to fix the circuit board 2 relative to support means 5 and / or can come into operative connection with support means 5.

[0042] The fixing element 4 is formed as a recess 4a, which in this case is realized by a bore 4b. The bore 4b is located in the center of the circular circuit board 2 and offers the advantage that the fixing element 4 can be manufactured cost-effectively in the circuit board 2 using a drilling tool.

[0043] The inclination sensor 100 also comprises the carrier unit 5, which is designed to receive and align the circuit board 2 and comprises a support section 7 for the circuit board 2.

[0044] The support section 7 is annular. Specifically, the support section 7 is formed by an annular receiving surface that, when the sensor unit 1 is assembled, comes into contact with the circuit board 2, in particular with the underside of the circuit board 2. In the illustrated inclination sensor 100, the support unit 5 is formed by a housing underside 11 of the inclination sensor 100.

[0045] On the outside, the housing bottom 11 includes an invisible base and / or contact surface for attaching the inclination sensor 100 to an external object and thus implementing relative positioning between the inclination detection means 103 and the external object. Advantageously, at least one inclination angle of the external object can thus be detected via the inclination sensor 100.

[0046] The carrier unit 5 also has a fixing section 6, which in the present embodiment comprises an internal thread.

[0047] Furthermore, the inclination sensor 100 according to the invention comprises rigid and elastic positioning means 8, 9.

[0048] The rigid positioning means 8 are designed to interact with the fixing element 4 and / or the bore 4b. The rigid positioning means 8 rigidly connect the circuit board 2 to the support unit 5. In the present case, the rigid positioning means 8 comprise a screw 8a, which is positively received in the bore 4b and can be secured in the internal thread of the fixing section 6.

[0049] The elastic positioning means 9 are designed such that the circuit board 2 is pressed onto the support section 7 with a specific force F, whereby the circuit board 2 and / or the support unit 5 can expand transversely to the applied force F in order to compensate for thermally induced stresses. Advantageously, the invention thus enables such mechanical stresses to not have a negative effect on the sensor output signal of the inclination detection means 103.

[0050] The elastic positioning means 9 are formed by an O-ring 9a. To press the circuit board 2 onto the support section 7, the elastic positioning means 9 also comprise a housing top 12. In the closed state of the inclination sensor 100, in which the housing top 12 is secured to the housing bottom 11 by four fixing screws 14a-d, the O-ring 9a undergoes a deformation and is thus deformed to generate the force F acting on the circuit board 2 and thus press the circuit board 2 onto the support section 7.

[0051] Furthermore, the illustration shows that the board 2 includes a notch 10 on its edge. The notch 10 advantageously allows the alignment of the board 2 to the carrier unit 5 to be symbolically represented during manual and / or hand-made production, allowing it to be estimated by a production employee. Furthermore, the notch 10 also allows a visual inspection to check the positioning of the board 2 after partial assembly.

[0052] It is also preferred if the notch 10 interacts with a centering element of the housing, i.e., either the housing bottom 11 or the housing top 12. This advantageously completely prevents the circuit board 1 from rotating around the central bore 4b as a result of a force being applied.

[0053] To provide moisture protection, the inclination sensor 100 includes two additional O-rings 13a / b, which are partially received in a notch or annular recess 16 of the support unit 5. This advantageously prevents moisture from penetrating the interior of the inclination sensor 100. The two O-rings 13a / b improve the sealing of the interior of the sensor unit 1 against moisture penetration when closed.

[0054] Fig. 2 shows the inclination sensor 100 known from Fig. 1 in the assembled and / or closed state.

[0055] In the closed state, the housing top 12 is secured to the housing bottom 11 by means of the four fixing screws 14a-d. The O-ring 9a, which is enclosed by the elastic positioning means 9, is thereby subjected to such a force that it deforms, causing a force F to act on the circuit board 2, pressing the circuit board 2 onto the support section 7.

[0056] Furthermore, two connection contacts 15a / b can be seen in this illustration, which are used for the power supply and / or communication connection of the inclination sensor 100.

[0057] Fig. 3 shows a sectional view of the inclination sensor 100 according to Fig. 2. The deformed state of the O-ring 9a can be seen from the sectional view.

[0058] Furthermore, it can be seen from this view that the housing formed from the housing top 12 and the housing bottom 11 forms an inner cavity which accommodates the circuit board 2.

[0059] In addition, the sectional view symbolically depicts the force F acting on the circuit board 2, which presses the circuit board 2 onto the annular support section 7 of the carrier unit 5. Figure 4 shows a sectional view of the sensor unit 1 according to the invention according to a further embodiment.

[0060] The circuit board 2, which has a round outer contour in a plan view, includes a central bore 4b to form the fixing element 4. The bore 4b is designed to receive a screw 8a to rigidly connect the circuit board 2 to the carrier unit 5 in a fixed state.

[0061] The circuit board 2 with the detection means 3 fixed on the underside is positioned between a housing top 12 and a housing bottom 11 of the sensor unit 1.

[0062] The underside of the circuit board 2 rests at the edge and / or radially outward on an annular support section 7 or a support surface of the carrier unit 5. In the present exemplary embodiment, the carrier unit 5 is formed entirely by the housing bottom 11 of the sensor housing. The annular support section 7 aligns the circuit board 2 within a plane, in the present sectional view within a horizontal plane.

[0063] In the assembled and / or closed state shown, the upper side of the circuit board 2 is subjected to force by the elastic positioning means 9 in order to press the circuit board 2 onto the annular support section 7.

[0064] The elastic positioning means 9 comprise an elastic O-ring 9a. The housing top 12 includes a groove and is connected to the housing bottom 11 via connecting means not shown in detail. The groove is designed to accommodate the O-ring 9a such that, in the closed state, the O-ring 9a is clamped between the housing top 12 and the circuit board 2, thus generating a force that presses the circuit board onto the support section 7.

[0065] The O-ring 9a is made of NBR (Nitrile Butadiene Rubber or Styrene Butadiene Rubber), with a hardness of essentially 70 Shore A.

[0066] The total diameter of the O-ring 9a in the present embodiment is 42 mm. Furthermore, the O-ring 9a has a cord diameter of essentially 2 mm in the unloaded state. An advantage in this context is that O-rings made of this material can be obtained inexpensively.

[0067] The cord diameter of essentially 2 mm is reduced to a height of essentially 1.5 mm in the assembled state, where the housing top 12 is force-locked to the housing bottom 11 via fixing elements. The elastic O-ring 9a thus generates a force acting on the circuit board 2, which acts transversely to the plane of extension of the circuit board 2 and presses the circuit board 2 onto the annular support section 7 of the carrier unit 5.

[0068] The contact pressure acting on the circuit board 2 is in particular in a range between 50N and 800N, preferably 150N to 600N, particularly preferably 154N to 594N. The fluctuation range results from the tolerances of the height of the installation space and / or the cord thickness of the O-ring, whereby the effect according to the invention is achieved within the entire range.

[0069] If a temperature change occurs, the circuit board 2 can expand independently of the support unit 5 and / or the housing underside 11. The underside of the circuit board 2 slides on the support section 7. In other words, the round circuit board 2 can move in the radial direction relative to the support unit 5 and / or the housing underside 11, starting from the fixing element 4, which is formed in the region of the center of the circuit board 2. This advantageously completely prevents mechanical distortion, which would have adverse effects on the detection means 3, as a result of different thermal expansion coefficients.

[0070] As a result, the present invention provides a thermal design for a sensor unit in a surprisingly simple manner, which not only can be manufactured and / or produced at low cost, but also prevents a negative influence on the measurement signal of the sensor unit in the event of large temperature fluctuations.

Claims

PATENT CLAIMS 1. Sensor unit (1) comprising a circuit board (2) with detection means (3) and at least one fixing element (4), a carrier unit (5) comprising a fixing section (6) and a support section (7) for receiving and aligning the circuit board (2), rigid positioning means (8) and elastic positioning means (9), wherein the rigid positioning means (8) are operatively connected to the fixing element (4) of the circuit board (2) and the fixing section (6) of the carrier unit (5) such that the circuit board (2) is rigidly connected to the carrier unit (5) in the region of the fixing element (4), and the elastic positioning means (9) press the circuit board (2) onto the support section (7) such that the circuit board (2) is slidably supported relative to the support section (7) of the carrier unit (5) in order to compensate for thermally induced mechanical stresses, in particular within the plane of extension of the circuit board (2) and / or substantially transversely to the pressing force of the elastic positioning means (9),is movably connected., 2. Sensor unit according to claim 1, characterized in that the fixing element (4) is designed as a recess (4a), in particular a bore (4b), which is closed in particular on the circumference.

3. Sensor unit according to claim 1 or 2, characterized in that the rigid positioning means (8) are designed as a form-fitting connection element (8a), preferably as a bolt and / or a retaining pin and / or a screw (8b).

4. Sensor unit according to one of the preceding claims, characterized in that the elastic positioning means (9) are round and / or circular and / or annular, in particular as an O-ring (9a), and / or that the support section (7) is round and / or circular and / or annular.

5. Sensor unit according to claim 4, characterized in that the fixing section (6) is arranged within or centrally to the annular support section (7).

6. Sensor unit according to one of the preceding claims, characterized in that the circuit board (2) comprises at least one notch (10) on the edge side, which preferably extends on the outside along a partial section, in particular a partial circle section.

7. Sensor unit according to one of claims 1 to 6, characterized in that the carrier unit (5) is designed as a housing underside (11) of the sensor unit (1), in particular the housing underside of the inclination sensor.

8. Sensor unit according to claim 7, characterized in that the sensor unit (1) comprises a housing top side (12), wherein in a closed state of the sensor unit (1) the housing top side (12) can be fixed on the housing bottom side (11) in such a way that the elastic positioning means (9) can be subjected to force to produce a deformation in order to press the circuit board (2) onto the support section (7) by means of the elastic positioning means (9).

9. Sensor unit according to one of the preceding claims, wherein the sensor unit (1) is designed as an inclination sensor (100) and the detection means (3) is designed as an inclination detection means (103).

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