Method for constructing force sensor assembly and force sensor assembly of motor vehicle

Abstract

The invention provides a method for constructing a force sensor assembly (100). The method comprises the following steps:-(S1) providing an expansion body (16) with an integrated force sensor element (14),-(S2) providing a printed circuit board (12) with electronic components which are designed to receive a measurement signal from the force sensor element (14),-(S3) electrically connecting the printed circuit board (12) to the force sensor element (14) of the expansion body (16),-(S4) electrically connecting the printed circuit board (12) to the force sensor element (14) of the expansion body (16). (S4) protecting the electrical connection structure by applying a casting compound to the electrical connection structure, and (S5) encapsulating the printed circuit board (12) in a media-tight manner and encapsulating the expansion body (16) in a media-tight manner at least in some regions, the force sensor element (14) is provided for sealing the electronic component and the force sensor element (14) or for sealing and mechanically protecting the electronic component and the force sensor element (14).

Description

Technical Field

[0001] The present invention generally relates to the field of force sensors for motor vehicles. In particular, the present invention relates to a method for producing a force sensor assembly, a force sensor assembly, and a motor vehicle having such a force sensor assembly. Background Art

[0002] Force sensors for motor vehicles (for example for use on brake pistons of motor vehicles) are usually subject to harsh ambient conditions. In such environments, high temperatures, brake dust and splashing water may occur. Furthermore, the force sensor must be able to withstand stone impacts and most chemicals found in motor vehicles. In addition, possible high-pressure cleaners and / or stone impacts and other mechanical loads must not affect the function of the force sensor.

[0003] A sealing method for encapsulating a force sensor by thermoplastic is known from CN 213180430. In order to close the resulting gap and fix the components to each other, it is proposed to provide a connection structure by laser welding.

[0004] However, the known methods for sealing force sensors are complex and require high precision in order to be able to ensure a certain degree of sealing. In addition, most known seals only primarily provide protection against mechanical loads. Summary of the invention

[0005] The object of the present invention is to at least partially eliminate the above-described disadvantages in force sensor assemblies for motor vehicles. In particular, the object of the present invention is to provide a simple and efficient method for constructing a force sensor assembly for a motor vehicle, wherein the force sensor assembly constructed in this way is sealed in an advantageous manner with respect to chemicals or media and is preferably optimally protected from mechanical loads.

[0006] The above-mentioned object is achieved by a method with the features of claim 1, by a force sensor arrangement for a motor vehicle with the features of claim 10, and by a motor vehicle with the features of claim 14. Further features and details of the invention are derived from the dependent claims, the description and the drawings. Features and details described in conjunction with the method according to the invention are of course also applicable in conjunction with the force sensor arrangement and / or the motor vehicle according to the invention, and vice versa, so that reference is always made to each other or can be made to each other with respect to the disclosures relating to the individual inventive aspects.

[0007] Embodiments of the present invention may advantageously provide an improved method for constructing a force sensor assembly for a motor vehicle. This method may be used to construct a stable and durable force sensor assembly for a motor vehicle in an efficient and simple manner.

[0008] A first aspect of the present disclosure relates to a method for constructing a force sensor assembly, in particular for a motor vehicle. The method comprises the following steps:

[0009] - providing an expansion body with an integrated force sensor element,

[0010] - providing a printed circuit board with electronic components designed to receive a measurement signal from the force sensor element,

[0011] - electrically connecting the printed circuit board to the force sensor element of the expansion body,

[0012] - protecting the electrical connection structure by applying a casting compound to the electrical connection structure, and

[0013] The printed circuit board is injection-molded in a medium-tight manner and the expansion body is injection-molded in a medium-tight manner at least in regions in order to seal the electronics and the force sensor element or to seal and mechanically protect the electronics and the force sensor element.

[0014] In other words, a first structural component including an equipped printed circuit board with an assembled and contact-connected plug can be provided or manufactured. Subsequently or simultaneously, a second structural component including an expansion body with an integrated force sensor element can be provided. The force sensor element can be a strain gauge. The strain gauge can be mounted on the expansion body. In another method step, the two structural components (especially the force sensor element and the printed circuit board) can be electrically connected to each other. In addition, the two structural components can be mechanically connected to each other, for example by locking or bonding. The electrical connection between the printed circuit board and the expansion body or the force sensor element of the expansion body can be achieved by bonding. Therefore, the electrical connection can be called a bonded connection (Bondverbindung).

[0015] The electrical connection structure can then be protected by applying a potting compound. For this purpose, a liquid potting compound (also known as a glob top potting compound) can be used. The potting compound can harden and thus protect the electrical connection structure from external influences.

[0016] In the last method step, the printed circuit board and the expansion body can be sealed at least in places by means of a media-tight encapsulation. In other words, the system comprising the two components can be encapsulated.

[0017] In the context of the present disclosure, the expansion body can be configured as a donut-shaped. Another embodiment is a circular expansion body. Other shapes, such as a pad or others, should not be explicitly excluded. The printed circuit board can be configured as a flat ring or in other shapes adapted to the expansion body. The expansion body can be a material piece that can be deformed under the action of a force, such as metal or plastic or others. The deformation can be detected and / or measured due to the force sensor element.

[0018] Different materials can be used for the media-tight encapsulation by injection molding. A casting solution or a lacquer can be used. A thermosetting material can be used as a casting solution. In principle, silicone, epoxide and / or polyurethane or other materials can be used as thermosetting materials. Silicone is highly elastic and soft and can withstand temperatures of up to 200° C. Epoxides offer high hardness and have high resistance to heat and chemicals. Polyurethane is also very suitable as a thermosetting plastic, but can only withstand temperatures of up to 120° C.

[0019] In principle, the thermosetting plastic material can be optimized with the aid of the filler in such a way that the thermal expansion coefficient of the material itself approaches that of the printed circuit board or of the electrical component, but also of the expansion body.

[0020] In this way, the mechanical stability of the entire force sensor assembly can be increased. Furthermore, the media-tight encapsulation can provide not only mechanical protection for the entire force sensor assembly but also a seal against chemicals. The media-tight seal can advantageously ensure protection against chemical environmental influences. The chemical can be, for example, a fuel or a cleaning fluid. The mechanical protection can ensure protection against mechanical loads, wherein the mechanical loads can include vibrations and / or oscillations.

[0021] According to one embodiment of the method, the step of media-tight encapsulation has the following intermediate steps:

[0022] - sealingly positioning the open housing at the expansion body, and

[0023] A thermosetting plastic, in particular a still liquid thermosetting plastic, is introduced into the open housing in order to injection-mold the printed circuit board in a medium-tight manner and to injection-mold the expansion body at least in places in a medium-tight manner.

[0024] The open housing can in principle be a frame that can be installed in a sealing manner at the contour of the expansion body. The open housing is preferably installed in a form-fitting and sealing manner, especially in a sealing manner relative to the casting solution, at the expansion body. The open housing should be especially positioned in a sealing manner at the expansion body so that no thermosetting plastic can invade between the two elements. When the open housing is positioned in a sealing manner at the expansion body, the open housing preferably forms a cavity into which the thermosetting plastic can be introduced. Therefore, the internal contour of the open housing can be consistent with the contour of the expansion body. For example, the open housing can be embodied as an open cylinder. In addition, the open housing can have a latching unit, which is designed to latch and / or mechanically fix the open housing at the expansion body.

[0025] It should be noted that after the thermoset plastic is introduced, the thermoset plastic preferably hardens.

[0026] The hardened thermosetting plastic has excellent chemical resistance to most environmental influences. Therefore, the printed circuit board and at least partially the expanded body can be protected from chemicals and mechanical stresses in a simple and efficient manner.

[0027] According to an embodiment of the method, when the thermosetting plastic is introduced into the open housing, the open housing is pressed onto the expansion body with a predetermined pressure. It can be ensured that when the thermosetting plastic, in particular the still liquid thermosetting plastic, is introduced, only the desired volume and / or the desired area at the printed circuit board and at the expansion body are sealed by the thermosetting plastic. As far as possible, no gap should be generated between the open housing and the expansion body, so it can be proved to be advantageous to press the open housing onto the expansion body with a predetermined pressure. As a result, the thermosetting plastic can be installed accurately and neatly. The predetermined pressure can be approximately between 40 bar and 60 bar.

[0028] According to one embodiment of the method, after the thermosetting plastic has been introduced into the open housing and in particular after the thermosetting plastic has hardened, the open housing is removed from the force sensor assembly. For this purpose, the open housing can be expandable, for example. It is also conceivable that after the thermosetting plastic has been introduced, pressing the open housing onto the expansion body with a predetermined pressure is stopped.

[0029] When removing the open housing, the open housing can be broken off. It can prove to be advantageous, for example, if the open housing is designed in one piece and is flush with the expansion body, for example by extrusion.

[0030] According to one embodiment of the method, the open housing / the open housing has a thermoplastic. Therefore, it can be proved to be particularly advantageous that a sealed connection between the expansion body and the open housing can be achieved. The sealed connection between the two elements can make it possible to introduce thermosetting plastics accurately and efficiently. Thermoplastic materials can provide good adhesion of the open housing to the expansion body.

[0031] According to one embodiment of the method, a thermosetting plastic is injected during the media-tight injection molding of the printed circuit board and at least partially the media-tight injection molding of the expansion body, thereby making it possible to effectively seal the electronic components and the force sensor element and protect them from mechanical loads.

[0032] According to an alternative embodiment of the method, the open housing / the open housing is fixed to the expansion body. In addition, a thermosetting plastic is poured into the open housing up to a predetermined level. For this purpose, it can be provided that the open housing is irreversibly fixed to the expansion body, for example by bonding. Therefore, the open housing can be designed not to be removed after the introduction of the thermosetting plastic. Therefore, according to this method, the force sensor assembly can be an open container. Unlike the embodiment in which the open housing is designed to be removed, the embodiment provides the advantage that no pressure needs to be applied to the open housing during the introduction of the thermosetting plastic. However, a force sensor assembly constructed in this way obviously takes up more space.

[0033] According to one embodiment of the method, the thermosetting plastic is poured into the open housing while applying a vacuum. This allows the method to be further improved.

[0034] According to one embodiment of the method, the step of media-tight encapsulation has the following intermediate steps:

[0035] - positioning, in particular fixing, the open housing in a sealing manner on the expansion body, and

[0036] The printed circuit board and the expanded body are painted at least in places with a paint.

[0037] In other words, it is conceivable to protect the finished device (i.e. the printed circuit board) and at least partially the expansion body by means of a paint. Here, the structural assembly with the printed circuit board and the expansion body with an open housing (especially a molded housing) can be poured with paint. The excess paint can then be poured out. For this purpose, the force sensor assembly can be tilted 180° for a predefined time. The paint that is attached to the printed circuit board or to the electronic components of the printed circuit board and in particular to the plug assembly of the printed circuit board then protects the sensitive electronics from chemical environmental influences.

[0038] As a result, chemical protection of the electrical components and the force sensor element can be ensured in an efficient manner. This method can achieve a lower production outlay.

[0039] A second aspect of the invention relates to a force sensor assembly for a motor vehicle. The force sensor assembly comprises: an expansion body with an integrated force sensor element, a printed circuit board with electronic components, the electronic components being designed to receive measurement signals from the force sensor element and to produce at least one electrical connection structure between the printed circuit board and the expansion body. The force sensor assembly also comprises a medium-tight seal of the printed circuit board and the expansion body at least partially. The medium-tight seal is in particular constructed to seal the electronic components and the force sensor element or to seal and mechanically protect the electronic components and the force sensor element.

[0040] All advantages explained above for the method according to the first aspect of the present invention also apply to the force sensor arrangement for a vehicle according to the second aspect of the present invention.

[0041] According to one embodiment of the force sensor arrangement, the media-tight seal comprises a thermosetting plastic.

[0042] According to one embodiment of the force sensor arrangement, the force sensor arrangement further comprises an open housing which is fastened in a sealing manner to the expansion body and in particular to the printed circuit board.

[0043] According to one embodiment of the force sensor assembly, the force sensor assembly is constructed according to the method according to the first aspect of the present invention.

[0044] A third aspect of the present invention relates to a motor vehicle having a force sensor arrangement according to the second aspect of the present invention.

[0045] All disclosures described above and below with respect to one aspect of the disclosure are equally applicable to all other aspects of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The present invention will be described in more detail below with the aid of the accompanying drawings.

[0047] Figure 1 A perspective view showing a printed circuit board with an expansion body,

[0048] Figure 2 A force sensor assembly according to one embodiment is shown,

[0049] Figure 3 A force sensor assembly according to another embodiment is shown,

[0050] Figure 4A force sensor assembly according to another embodiment is shown, and

[0051] Figure 5 A flow chart of a method according to one embodiment is shown. DETAILED DESCRIPTION

[0052] Similar, similarly acting, identical or identically acting elements are provided with similar or identical reference numerals in the drawings. These drawings are schematic only and are not to scale.

[0053] Figure 1 A perspective view of a printed circuit board with an expansion body is shown. The expansion body 16 is configured in a donut-shaped or tire-shaped manner and has force sensor elements 14, which can be configured as strain gauges. The expansion body 16 can also be configured as a ring, wherein a printed circuit board 12 is mounted or fixed on the first end side of the ring. The force sensor element is preferably mounted at the first end side of the ring or the expansion body. The force sensor elements 14 can be evenly distributed at the first end side of the expansion body 16. The force sensor elements 14 can be distributed rotationally symmetrically.

[0054] The printed circuit board 12 can also be constructed in an annular shape. The printed circuit board 12 can have a hole 18, which is used to position the printed circuit board 12. The printed circuit board 12 is preferably connected to the expansion body mechanically and chemically (adhesive). Alternatively, the printed circuit board 12 can be fixed to the expansion body by means of a mechanical connection structure, for example by means of a locking structure. In addition, the printed circuit board 12 is electrically connected to the force sensor element 14 of the expansion body. The printed circuit board 12 of the force sensor assembly 100 can have recesses 13 or holes, which are arranged above the corresponding force sensor elements 14 when the printed circuit board 12 is installed on the expansion body 16. The distribution of the recesses 13 of the printed circuit board 12 is consistent with the distribution of the force sensor elements 14 of the expansion body 16, and they can also be located at the edge of the printed circuit board, so that holes do not need to be formed.

[0055] The electrical components (not shown here) of the printed circuit board 12 are designed to receive the signals of the force sensor element 14. It should be noted that between the expansion body 16 and the printed circuit board 12, a support surface can be arranged at least partially or locally on the expansion body to enable stable support of the printed circuit board.

[0056] also, Figure 1 Force sensor element 14 is covered with a protective material or potting compound in the cavity formed by opening or recess 13 in printed circuit board 12 .

[0057] Figure 2 A force sensor assembly 100 is shown according to one embodiment. Unless otherwise specified, Figure 2The printed circuit board 12 and the expansion body 16 have Figure 2 The printed circuit board 12 and the expansion body 16 are the same elements and / or components. Figure 2 A cross section of the force sensor assembly 100 is shown, wherein the cross section is along the axis A, see Figure 1 .

[0058] The force sensor arrangement 100 has a printed circuit board 12 and a media-tight seal of an at least partially expanded body. Figure 2 The media-tight seal of the force sensor assembly 100 consists of an injection-molded thermosetting plastic 10. For this purpose, an open housing 19 is already positioned sealingly on the expansion body 16. The expansion body 16 can have a surrounding latching unit 15, by which the open housing 19 can be positioned sealingly on the expansion body 16. The open housing 19, together with the printed circuit board 12 and the expansion body 16, forms a cavity, which can be filled with the thermosetting plastic 10. The thermosetting plastic can be introduced into the open housing 19 or into the cavity formed thereby under pressure.

[0059] The thermosetting plastic 10 can then be cured. For this purpose, provision can be made to wait for a curing time. Finally, after the thermosetting plastic 10 has cured, the open housing 19 is removed. The thermosetting plastic 10 covers and thus protects each electronic component of the printed circuit board 12 and the force sensor elements 14 of the expansion body 16 from mechanical loads and chemical environmental influences. The thermosetting plastic 10 is preferably not in direct contact with the force sensor elements 14, since these can be covered by a potting compound or a globular encapsulation.

[0060] Figure 3 FIG. 1 shows a force sensor assembly 100 according to another embodiment. Unless otherwise specified, Figure 3 The force sensor assembly 100 has a Figure 2 The force sensor assembly 100 may have the same elements and / or components.

[0061] Different from Figure 2 The force sensor assembly 100, Figure 3 The force sensor assembly 100 has an open housing 19. The open housing 19 is fixed, preferably irreversibly fixed, to the expansion body 16. The open housing 19 thus rests on the expansion body 16 in a form-fitting manner around the expansion body 16. The open housing 19, which can also be referred to as a frame, forms a cavity that can be filled with a thermosetting plastic 10. After the housing 19 has been fixed to the expansion body 16, the thermosetting plastic can subsequently be poured (especially without pressure) into the cavity formed by the housing up to a predetermined level 17.

[0062] The thermosetting plastic 10 thus forms a seal for the electronics and the force sensor element 14 or a seal and a mechanical protection for the electronics and the force sensor element 14 .

[0063] Figure 4 FIG. 1 shows a force sensor assembly 100 according to another embodiment. Unless otherwise specified, Figure 4 The force sensor assembly 100 has a Figure 2 and Figure 3 The same elements and / or components as the force sensor assembly 100 of FIG. Figure 3 Similar to the force sensor assembly 100, Figure 4 The force sensor assembly 100 also has an open housing 19 forming a frame. The printed circuit board 12 and at least partially the expansion body 16 can be protected from chemical environmental influences by means of the varnish 11. The force sensor assembly 100 can be filled with the varnish together with the molded housing 19 and then emptied again (inverted). The varnish adhering to the printed circuit board 12, the expansion body 16 and the open housing 19 then protects the sensitive electronics of the force sensor assembly 100 from chemical environmental influences. The varnish 11 can form a continuous thin layer, which extends in particular from the outer inner wall of the open housing 19 to the inner inner wall of the open housing 19.

[0064] Figure 5 A flow chart of a method for constructing a force sensor assembly 100, in particular a force sensor assembly 100 for a motor vehicle, according to an embodiment is shown. The method has the following steps: In a first method step S1, an expansion body 16 with an integrated force sensor element 14 is provided. The force sensor element 14 is designed to detect and / or measure the expansion of the expansion body 16. In a second method step S2, which is preferably performed immediately after the first method step S1, a printed circuit board 12 with electronic components is provided. The electronic components are designed to receive a measurement signal from the force sensor element 14. In a third method step S3 following the second method step, the printed circuit board 12 is electrically connected to the force sensor element 14 of the expansion body 16, in particular by means of a bonding connection. In a fourth method step S4, the electrical connection structure is protected by applying a casting compound, such as a round top encapsulation, which is cast onto the electrical connection structure. In other words, the bonding connection structure is protected by the round top encapsulation in the fourth method step. In a final fifth method step S5, printed circuit board 12 is injection molded in a medium-tight manner and expansion body 16 is injection molded in a medium-tight manner at least in regions in order to seal the electronics and force sensor element 14 or to seal and mechanically protect the electronics and force sensor element 14. The entire system can thereby be encapsulated, whereby force sensor assembly 100 can be advantageously protected from mechanical loads or force sensor assembly 100 can be advantageously protected from chemical ambient influences and mechanical loads.

[0065] The fifth method step S5 may have the following intermediate steps:

[0066] Casting the printed circuit board 12 in a medium-tight manner and at least partially casting the expansion body 16 in a medium-tight manner for sealing the electronics and the force sensor element 14 or for sealing and mechanically protecting the electronics and the force sensor element 14 .

[0067] The printed circuit board 12 is varnished in a medium-tight manner and the expansion body 16 is varnished at least in places in a medium-tight manner for sealing the electronics and the force sensor element 14 or for sealing and mechanically protecting the electronics and the force sensor element 14 .

[0068] It should be noted that the terms "comprising" and "having" do not exclude other elements and that the indefinite article "a" or "an" does not exclude a plurality. It should also be noted that features and steps described with reference to one of the above embodiments can also be used in combination with other features and steps of other embodiments described above. Reference signs in the claims should not be considered as limiting.

[0069] Reference numerals list

[0070] 100 force sensor assembly

[0071] 10 Thermosetting plastics

[0072] 11 Paint

[0073] 12 Printed Circuit Board

[0074] 13 blank space

[0075] 14 Force sensor element

[0076] 15 card lock unit

[0077] 16 expansion body

[0078] 17 pre-given levels

[0079] 18 holes

[0080] 19 Open housing

[0081] S1 First method step

[0082] S2 Second method step

[0083] S3 Third method step

[0084] S4 Fourth method step

[0085] S5 Fifth method step

Claims

1. A method for constructing a force sensor assembly (100), the method comprising the following steps: - (S1) providing an expansion body (16) with an integrated force sensor element (14), - (S2) providing a printed circuit board (12) having electronic components, the electronic components being designed to receive a measurement signal from the force sensor element (14), - (S3) electrically connecting the printed circuit board (12) and the force sensor element (14) of the expansion body (16), - (S4) protecting the electrical connection structure by applying a casting compound to the electrical connection structure, and (S5) media-tightly encapsulating the printed circuit board (12) and at least partially media-tightly encapsulating the expansion body (16) for sealing the electronic component and the force sensor element (14) or for sealing and mechanically protecting the electronic component and the force sensor element (14).

2. The method according to claim 1, in, The step of media-tight encapsulation ( S5 ) comprises the following intermediate steps: - sealingly positioning the open housing (19) on the expansion body (16), and A thermosetting plastic (10) is introduced into the open housing (19) in order to encapsulate the printed circuit board (12) in a medium-tight manner and to encapsulate the expansion body (16) at least in places in a medium-tight manner.

3. The method according to claim 2, in, When the thermosetting plastic (10) is introduced into the open housing (19), the open housing (19) is pressed onto the expansion body (16) with a predetermined pressure.

4. The method according to claim 2 or 3, in, After the thermosetting plastic (10) has been introduced into the open housing (19), the open housing (19) is removed from the force sensor assembly (100).

5. The method according to any one of the preceding claims, in, The open housing (19) comprises a thermoplastic.

6. The method according to any one of the preceding claims, in, A thermosetting plastic is injected during the media-tight injection molding of the printed circuit board (12) and at least partially the media-tight injection molding of the expansion body (16).

7. The method according to any one of the preceding claims 1 to 3 and 5 to 6, in, The open shell / the open shell (19) is fixed to the expansion body (16), and A thermosetting plastic (10) is poured into the open housing (19) up to a predetermined level (17).

8. The method according to claim 7, in, The thermosetting plastic (10) is poured into the open housing (19) while applying a vacuum.

9. The method according to any one of the preceding claims, in, The step of media-tight encapsulation has the following intermediate steps: - positioning, in particular fixing, the open housing (19) in a sealing manner on the expansion body (16), and The printed circuit board (12) is painted with a paint (11) and the expansion body (16) is painted at least in places.

10. A force sensor assembly (100) for a motor vehicle, the force sensor assembly having An expansion body (16) with an integrated force sensor element (14), a printed circuit board (12) with electronic components designed to receive measurement signals from the force sensor element (14) and to produce at least one electrical connection between the printed circuit board (12) and the expansion body (16), in, The force sensor assembly (100) also has a medium-tight seal of the printed circuit board (12) and at least partially of the expansion body (16).

11. The force sensor assembly (100) according to claim 10, in, The media-tight seal comprises a thermosetting plastic (10).

12. The force sensor assembly (100) according to one of claims 10 and 11, in, The force sensor arrangement further comprises an open housing (19) which is fastened sealingly to the expansion body (16) and in particular to the printed circuit board (12).

13. The force sensor assembly (100) according to any one of claims 10 to 12, in, The force sensor assembly (100) is constructed according to the method according to any one of claims 1 to 9. 14 . A motor vehicle comprising a force sensor arrangement ( 100 ) according to claim 10 .

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