Sensor unit with rigid and elastic positioning means

Abstract

The present invention relates to a sensor unit comprising a circuit board with sensing means and at least one fixing element, a carrier unit comprising a fixing section and a support section for receiving and aligning the circuit board, and rigid and elastic positioning means, wherein the rigid positioning means are operatively connected to the fixing element of the circuit board and the fixing section of the carrier unit in such a way that the circuit board is rigidly connected to the carrier unit in the area of ​​the fixing element, and the elastic positioning means press the circuit board onto the support section in such a way that the circuit board is movably connected relative to the support section of the carrier unit to compensate for thermally induced mechanical stresses.

Description

[0001] The present invention relates to a sensor unit according to claim 1.

[0002] Sensor units comprising a circuit board with detection means for detecting objects and / or physical quantities are generally known from the prior art.

[0003] 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. Therefore, in addition to characteristic properties of the sensor unit, such as measurement accuracy and / or acquisition speed, the thermal design of the sensor unit is also of crucial importance.

[0004] In thermal design, the different coefficients of thermal expansion of critical components, such as a circuit board for mounting and electrically connecting the detection means and the corresponding carrier unit of the sensor unit that mechanically holds the circuit board, must be taken into account so that they do not negatively affect the measurement result of the sensor unit.

[0005] In this context, various solutions are known from the state of the art.

[0006] Firstly, it is known to select critical components from special materials with low or – in the case of interacting materials – similar coefficients of thermal expansion. In practice, this is usually not feasible or leads to high material costs, while the manufacturer still only approves the use of the sensor unit for a narrow temperature range.

[0007] Furthermore, it is known from the prior art that the influence of a temperature change on the measurement result is compensated for by means of auxiliary electronics. Such auxiliary electronics determine the temperature directly or indirectly in order to calculate a correction value based on this temperature. Such a solution is not only complex and therefore expensive, but can also lead to a distortion of the measurement result of the sensor unit.

[0008] Consequently, the present invention aims to overcome the disadvantages known from the prior art. In particular, the present invention aims 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 difference in thermal expansion between the circuit board and the carrier unit does not negatively affect the detection means and thus the measurement result of the sensor unit.

[0009] This problem is solved by a device according to the invention as described in claim 1.

[0010] Advantageous embodiments of the invention are described in the dependent claims. The scope of the invention includes all combinations of at least two 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 sensing 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 contact 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 as well as elastic positioning means.

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

[0015] In other words, the rigid positioning means create a form-fit and / or force-fit 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 such effective contact with the circuit board that the circuit board is pressed onto the support section of the carrier unit with a specific force.

[0017] The elastic positioning elements and the support section interact in such a way that relative movement between the circuit board and the support unit is permitted, transverse to the force applied to the circuit board by the elastic positioning elements. This movable and / or elastic connection between the circuit board and the support unit allows the circuit board, particularly within its plane of extension, to expand and / or contract independently of the support unit. Advantageously, this prevents thermally induced mechanical stresses between the support unit and the circuit board, thus ensuring that these stresses do not affect the measurement result of the sensor unit, or only affect it to a permissible extent, while simultaneously allowing for the alignment of the circuit board.

[0018] 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 from the fixing element in longitudinal and transverse directions relative to the carrier unit.

[0019] In the contact area where 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 extent plane of the circuit board in which the circuit board is essentially formed.

[0020] The elastic positioning elements that press the circuit board against the support section of the carrier unit generate a force that acts essentially perpendicular to the plane of extension of the circuit board and is dimensioned such that the circuit board can expand perpendicular to a contact surface of the support section and / or perpendicular to the applied force to compensate for thermally induced mechanical stresses. Advantageously, the circuit board can thus slide along the support section, particularly along the contact surface, allowing the relative position between the circuit board and the carrier unit to change. Advantageously, the circuit board can therefore expand almost arbitrarily around the fixing element within the plane of extension.

[0021] Further development envisages that the fixing element be designed as a recess, in particular as a bore. Advantageously, this 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 on its circumference and designed as a hole and / or opening in the circuit board.

[0022] In a preferred embodiment of the sensor unit according to the invention, the rigid positioning means are designed as a positive-locking connecting element, preferably as a bolt and / or a retaining pin and / or a screw. Advantageously, the rigid positioning means can thus be realized using standardized components, which enables low material costs. Furthermore, a positive-locking connecting element and / or a screw interacts optimally with a recess, in particular a bore.

[0023] The elastic positioning elements are designed to be round and / or circular and / or ring-shaped, particularly as an O-ring. Additionally or alternatively, the support section is also designed to be round and / or circular and / or ring-shaped. This advantageously allows for large-area and / or uniform positioning and / or alignment of the circuit board.

[0024] In this context, it is particularly advantageous if the fixing section is arranged within the ring-shaped support section, preferably in the middle of the ring-shaped support section.

[0025] In other words, in this context, the annular support section, which is formed in particular by one or more annular surfaces and one or more partial circular surface segments, is intended to limit and / or define an area within which the fixing section is positioned. Thus, thermally induced mechanical stresses in the support unit and / or the circuit board can propagate around the fixing section in all directions, especially in all longitudinal and transverse directions.

[0026] Furthermore, in another preferred embodiment, it is planned that the circuit board comprises at least one notch on its edge, which preferably extends along the outside of a partial section, in particular a partial circular section.

[0027] The notch can advantageously simplify the assembly of the sensor unit, as the orientation of the circuit board to the carrier unit can thus be symbolically represented. This also simplifies the manufacturing of the sensor unit, as the arrangement of the circuit board to the carrier unit can be predetermined and / or graphically indicated to the assembly person.

[0028] In a further development, it is preferably provided that the carrier unit is designed as the lower housing of the sensor unit, in particular the lower housing of an inclination sensor. It is also advantageously provided that the carrier unit can be aligned relative to an external object via the lower housing, in order to detect, for example, the temperature and / or position and / or force and / or angle of the external object.

[0029] Further development envisages that the sensor unit includes a housing top, wherein, in a closed state of the sensor unit, the housing top can be fixed to the housing bottom in such a way that the elastic positioning means are deformed to apply a force that presses the circuit board onto the support section.

[0030] 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 as inclination detection means.

[0031] The invention is explained in more detail below by way of example with reference to the drawings. The combination of features shown in the exemplary embodiments can be supplemented by further features according to the above explanations, in accordance with the properties necessary for a specific application. Likewise, individual features can be omitted in the described embodiments, also in accordance with the above explanations, if the effect of that feature is not important in a specific application.

[0032] In the drawings, elements of the same function and / or structure are designated with the same reference symbol.

[0033] They show: Fig. 1: an exploded view of a sensor unit according to the invention in an exemplary embodiment; Fig. 2: a perspective view of the already known sensor unit according to the exemplary embodiment as well as Fig. 3: A schematic sectional view of the known sensor unit according to the exemplary embodiment.

[0034] The Fig. Figure 1 shows an exploded view of a sensor unit 1 according to the invention with detection means 3 according to a preferred embodiment.

[0035] In the illustrated embodiment, the sensor unit 1 according to the invention is designed as an inclination sensor 100.

[0036] The inclination sensor 100 according to the invention comprises inclination detection means 103 which are mechanically held on a circuit board 2 and electrically interconnected.

[0037] 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 contact with support means 5.

[0038] The fixing element 4 is designed 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.

[0039] The tilt sensor 100 also includes the carrier unit 5, which is designed to receive and align the circuit board 2 and includes a support section 7 for the circuit board 2.

[0040] The support section 7 is ring-shaped. Specifically, the support section 7 is formed by a ring-shaped receiving surface which, in the assembled state of the sensor unit 1, comes into contact with the circuit board 2, in particular with the underside of the circuit board 2.

[0041] The carrier unit 5 in the depicted tilt sensor 100 is formed by a housing underside 11 of the tilt sensor 100.

[0042] On the outside, the underside of the housing 11 includes a concealed standing and / or contact surface to fix the tilt sensor 100 to an external object and thus enable relative positioning between the tilt detection means 103 and the external object. Advantageously, at least one tilt angle of the external object can therefore be detected via the tilt sensor 100.

[0043] The carrier unit 5 also has a fixing section 6 which in the present embodiment includes an internal thread.

[0044] Furthermore, the tilt sensor according to the invention comprises 100 rigid and elastic positioning means 8, 9.

[0045] 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 this case, the rigid positioning means 8 are formed by a screw 8a, which is positively engaged by the bore 4b and can be secured in the internal thread of the fixing section 6.

[0046] 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. According to the invention, this advantageously prevents such mechanical stresses from having a negative effect on the sensor output signal of the tilt detection means 103.

[0047] 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 include a housing top 12. In the closed state of the tilt sensor 100, in which the housing top 12 is fixed to the housing bottom 11 by four fixing screws 14a-d, the O-ring undergoes 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.

[0048] Furthermore, the illustration shows that the circuit board 2 has a notch 10 on its edge. Advantageously, the notch 10 allows the orientation of the circuit board 2 relative to the carrier unit 5 to be symbolically represented during manual and / or hand-held manufacturing, thus enabling a production worker to estimate it. The notch 10 also allows for visual inspection to check the positioning of the circuit board 2 after partial assembly.

[0049] To provide a seal against moisture, the tilt sensor 100 includes two additional O-rings 13a / b, which are partially received by a notch 10 in the carrier unit 5. This advantageously prevents moisture from penetrating the interior of the tilt sensor 100.

[0050] The Fig. 2 shows the one from the Fig. 1 known tilt sensor 100 in the assembled and / or closed state.

[0051] In the closed state, the upper housing 12 is fixed to the lower housing 11 by means of the four fixing screws 14a-d. The O-ring 9a, which is encompassed by the elastic positioning means 9, is thereby subjected to such force that it deforms, which is why a force F acts on the circuit board 2, pressing the circuit board 2 onto the support section 7.

[0052] Furthermore, this illustration shows two connection contacts 15a / b, which are used for the power supply and / or communication connection of the tilt sensor 100.

[0053] The Fig. Figure 3 shows a sectional view of the tilt sensor 100 according to the Fig. 2. The deformed state of the O-ring 9a can be seen from the cross-sectional view.

[0054] Furthermore, this view shows that the housing formed from the upper housing surface 12 and the lower housing surface 11 forms an inner cavity that accommodates the circuit board 2.

[0055] In addition, the cross-sectional view symbolically shows the force F acting on the circuit board 2 in vector form, which presses the circuit board 2 onto the annular support section 7 of the carrier unit 5.

[0056] As a result, the present invention provides a surprisingly simple thermal design for a sensor unit that can not only 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

[1] Sensor unit (1), comprising a 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 board (2) and rigid and elastic positioning means (8, 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) in such a way 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) in such a way that the circuit board (2) is movably connected relative to the support section (7) of the carrier unit (5), in particular within the plane of extension of the circuit board (2) and / or transversely to the pressing force of the elastic positioning means (9), in order to compensate for thermally induced mechanical stresses. [2] Sensor unit according to claim 1 characterized by 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 by 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 bythat 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 by that the fixing section (6) is arranged within the, preferably centrally to the, annular support section (7). [6] Sensor unit according to one of the preceding claims, characterized by that the 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 by 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 byin 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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