Temperature sensor and method for manufacturing a temperature sensor

Abstract

Temperature sensor (1) comprising a first housing part (4) and a holder (7) made of plastic, wherein the first housing part (4) is directly connected to the holder (7), and comprising a sensor element (3) comprising a measuring body (13) and electrical wires (14) connected to the measuring body (13), wherein the sensor element (3) is partially arranged in the holder (7).

Description

[0001] The present invention relates to a temperature sensor. The temperature sensor can be an immersion temperature sensor. The temperature sensor can comprise an NTC measuring element made of glass.

[0002] The response time of a temperature sensor is a crucial parameter that significantly influences its performance and suitability for various applications. Conversely, good electrical insulation is essential to ensure the reliable operation and longevity of the temperature sensor. Often, the necessary electrical insulation results in a slower response time.

[0003] CN 206573231 U discloses a temperature sensor comprising a first encapsulation of a thermally conductive material and a second encapsulation of an epoxy resin. JP 4892030 B2 discloses a temperature sensor in which a sensor element and a conducting wire are covered with a coating material of amorphous or crystalline glass. The wire is partially guided through a ceramic shield.

[0004] One objective of the present invention is to provide an improved temperature sensor.

[0005] A temperature sensor comprises a housing and a holder made of plastic. The temperature sensor also includes a sensor element comprising a measuring body and electrical wires connected to the measuring body. The sensor element is partially enclosed within the holder.

[0006] The holder can be a pre-formed component. This means that the holder is provided in its pre-formed shape before being assembled with the sensor element. The first housing part can also be a pre-formed component. The first housing part can be directly connected to the holder. For example, the first housing part and the holder interact through a locking mechanism, such as a snap connection. The holder can have snap connections that engage with corresponding parts of the first housing part.

[0007] The first housing component can be a metal housing. The first housing component can be an external housing, i.e., a component configured to be in direct contact with the medium whose temperature is to be measured. The first housing component can be designed to be immersed in the medium.

[0008] By at least partially positioning the sensor element within the holder, electrical insulation can be ensured. In particular, electrical insulation of the wires from the metal housing can be guaranteed. The sensor element can be positioned in the holder in such a way that at least one interface between the wires and the sensor body is enclosed by the holder.

[0009] Furthermore, the holder can secure the position of the sensor element during the manufacturing of the temperature sensor. This prevents unwanted changes in position, such as displacement or deformation of the sensor element during subsequent manufacturing steps.

[0010] The measuring element may contain an NTC (negative temperature coefficient) core, specifically an NTC chip. The NTC core may have glass insulation. The wires may be connected to the measuring element via a paste, such as a gold / silver paste. The interface between the measuring element and the electrical wires may be enclosed by the holder.

[0011] The measuring element can be insulated only by glass and can be free of additional insulation. This allows the temperature-sensitive element to be positioned close to an inner surface of the first housing part, resulting in a fast response time.

[0012] A potting compound can fill a space between the first housing part and the measuring body. However, the potting compound is not a coating on the measuring body, but rather a material—in particular, the only material—that lies between the first housing part and the temperature-sensitive material of the measuring body. The potting compound can be a thermally conductive resin. The potting compound can fill a space between the first housing part and the holder.

[0013] The measuring element can protrude from the holder. This enables a fast response time of the temperature sensor. The dimensions of the measuring element and the holder can be such that the measuring element is partially located within the holder and partially protrudes from it. To secure the position of the measuring element, the inner diameter of the front section of the holder can be smaller than the maximum diameter of the measuring element.

[0014] The holder may have a separating rib located between the electrical wires. This ensures electrical insulation between the wires. A gap may be present between the measuring body and the separating rib to prevent damage to the measuring body.

[0015] Additionally or alternatively, the space between the electrical wires can be filled with a potting compound. The separating rib ensures that the position of the wires is maintained when the potting compound is poured into the space.

[0016] The holder may be partially enclosed by the first housing part and protrude from it at a rear end. The temperature sensor may have a second housing part that includes an interface between the first housing part and the holder. This second housing part may be an overmold that at least covers the interface. The holder may not be visible from the outside after the overmold has been applied.

[0017] A method for manufacturing a temperature sensor includes a step for positioning a sensor element in a plastic holder. The temperature sensor can be a temperature sensor as described above. The sensor element can include a measuring body and electrical wires connected to the measuring body. The sensor element is partially positioned in the holder. For example, the sensor element can be inserted into the holder.

[0018] The process can include a further step in which the space between the wires of the sensor element is filled with a potting compound. In this step, the position of the sensor element can be secured by the holder.

[0019] The process can include a further step in which a first housing part is provided and connected to the holder. The first housing part can be a metal housing. The connection can be made by a locking mechanism, such as a snap-fit ​​connection.

[0020] The process may include a further step in which an interface between the holder and the first housing part is covered by a second housing part. This second housing part may be a molded component. The second housing part may include fastening means for attaching the sensor element.

[0021] The present disclosure discloses a product and a process. Every feature described in relation to one of these aspects is also disclosed here in relation to the other aspect, even if the respective feature is not expressly mentioned in connection with the specific aspect.

[0022] Further features, refinements and advantages will become apparent from the following description of the exemplary embodiments in conjunction with the figures. Fig. Figure 1 shows an embodiment of a temperature sensor in a side view, Fig. 2 shows the temperature sensor Fig. 1 in a perspective view, Fig. Figure 3 shows a subassembly of an embodiment of a temperature sensor in a side view, Fig. Figure 4A shows a holder of an embodiment of a temperature sensor in a perspective view. Fig. 4B shows the holder Fig. 4A in a side view, Fig. Figure 5 shows a sensor element of an embodiment of a temperature sensor in a side view. Fig. Figure 6 shows a correctly positioned subassembly of an embodiment of a temperature sensor in a top view. Fig. Figure 7 shows a mispositioned subassembly in a top view. Fig. Figure 8 shows a detail of a subassembly of an embodiment of a temperature sensor in a side view, Fig. Figure 9 shows a first housing part of an embodiment of a temperature sensor in a side view, Fig. Figure 10 shows a subassembly of an embodiment of a temperature sensor in a side view, Fig. Figure 11 shows a subassembly of an embodiment of a temperature sensor with potting material in a side view, Fig. Figure 12 shows an embodiment of a temperature sensor with additional potting material in a side view, Fig. Figure 13 shows another embodiment of a temperature sensor in a perspective view, Fig. Figure 14 shows another embodiment of a temperature sensor in a perspective view, Fig. Figure 15 shows process steps of an embodiment of a method for manufacturing a temperature sensor in a schematic diagram. Fig. Figure 16 shows an intermediate state of a temperature sensor in the manufacturing process of Fig. 15.

[0023] In the figures, elements with the same structure and / or functionality may be designated with the same reference numerals. The embodiments shown in the figures serve for illustration purposes and are not necessarily drawn to scale.

[0024] Fig. Figure 1 shows an embodiment of a temperature sensor 1. The temperature sensor 1 has an outer housing 2 that encloses a sensor element 3 (see Figure 1). Fig. 3) The outer housing 2 can have a first housing part 4, which forms the tip 5 of the temperature sensor 1. The first housing part 4 is configured to be immersed in a medium whose temperature is to be measured. The medium can be, for example, a liquid or a gas. The first housing part 4 can be made of a metal.

[0025] Temperature sensor 1 can be used in a vehicle, e.g., a car. Temperature sensor 1 can be used, for example, to monitor the temperature of engine coolant or to determine the ambient air temperature.

[0026] The temperature sensor 1 can have a second housing part 6, which may be made of a plastic material, for example. The second housing part 6 may be a molded component. The second housing part 6 may cover an interface 12 between the first housing part 4 and a holder 7 (see figure). Fig. 12). The second housing part 6 forms a flange area 8. The temperature sensor 1 can be designed so that it can be inserted into an opening of a device with the first housing part 4 facing forward, the flange area 8 forming a support for fastening the temperature sensor 1.

[0027] Electrical conductors 9 protrude from the rear end of the second housing part 6. The electrical conductors 9 are insulated wires, although one rear end of the conductors 9 may be uninsulated to provide a terminal for an electrical connection.

[0028] The first housing part 4 can be formed by a pre-formed component. This means that the housing part is already provided in its geometric shape before assembly with other parts of the temperature sensor 1. The second housing part 6 can be formed as an overmold.

[0029] In this case, the geometric shape is formed using injection molding. In this case, the second housing part 6 is not a pre-formed component.

[0030] Fig. Figure 2 is a perspective view of a temperature sensor 1. Temperature sensor 1 may be the same or a similar sensor as in Figure 2. Fig. 1. A sealing element 10, e.g. an O-ring seal, can be arranged at the flange area 8.

[0031] Fig. Figure 3 shows a subassembly 11 of a temperature sensor 1. The subassembly 11 can be an internal part of the temperature sensor 1. Fig. 1 and Fig. 2. The subassembly 11 can be completely covered at its front end by the first housing part 4 and at its rear end by the second housing part 6.

[0032] Subassembly 11 comprises a sensor element 3, which is assembled with a holder 7. The sensor element 3 has a measuring body 13, which forms the head of the sensor element 3. The sensor body can be made of glass. The measuring body 13 can be made of NTC glass (negative temperature coefficient). The sensor element 3 has wires 14 for electrical connection to the measuring body 13.

[0033] The measuring element 13 can be insulated solely by glass, without any additional insulation. This improves the response time when detecting temperature changes. The measuring element 13 is located at the very top of an outer housing, in particular the first housing part 4, as shown in Fig. 1 shown.

[0034] The holder 7 can be made of plastic. The holder 7 can be a pre-formed component, for example, an injection-molded part. The holder 7 helps to secure the position of the measuring body 13 and the electrical wires 14.

[0035] The Fig. 4A and Fig. Figure 4B shows the holder 7 as a separate part before it is assembled with the sensor element 3. The holder 7 has a rear section 15 with snap connections 16 for locking an external housing part, such as the first housing part 4 in Fig. 1. The snap connections 16 are an integral part of the holder 7. It is also possible that the first housing part 4 is locked in a manner other than by snap connections.

[0036] The holder 7 has a front section 17 in which the measuring body 13 can be partially positioned. The inner diameter d of the front section 17 can be smaller than the maximum diameter of the measuring body 13. For example, the inner diameter d can be 0.9 mm and the maximum diameter of the measuring body 13 b can be 1.3 mm. If the measuring body 13 is partially positioned in the front section 17, positional deviation of the measuring body 13 can be prevented. In particular, lifting can be prevented.

[0037] Fig. Figure 5 shows sensor element 3. Fig. 3. The measuring body 13 has a maximum diameter b, the direction of which is perpendicular to the insertion direction of the measuring body b into the holder 7. The insertion direction is the same as the axial direction of the temperature sensor 1. At its rear portion, the measuring body 13 has a smaller diameter than the inner diameter d of the front portion 17 of the holder 7, so that the measuring body 13 can be partially positioned within the holder 7. Since the maximum diameter b is larger than the inner diameter d of the front portion 17 of the holder 7, displacement of the measuring body 13 in a direction perpendicular to the insertion direction can be prevented. Furthermore, the axial position of the measuring body 13 can be secured.

[0038] The measuring body 13 has a length l in the insertion direction. The length l can be, for example, 2.2 mm.

[0039] The wires 14 can be connected to the measuring body 13 using gold / silver paste. Afterwards, insulation made of glass can be applied. An interface 25, i.e., the point where the wires 14 are connected to the measuring body 13, can be enclosed by the holder 7 when the sensor element 3 is assembled with the holder 7.

[0040] The wires 14 of the sensor element 3 are shown connected to the leads 9. However, the connection can also be made after the sensor element 3 has been assembled with the holder 7. The wires 14 can be connected to the leads 9 using a connection method such as soldering, welding, or splicing. The wires 14 can be connected to the sensor body 3 using the same technologies. The wires 14 can be made of a metal such as copper and have a diameter ranging from, for example, AWG 28 to AWG 22.

[0041] Fig. Figure 6 shows a subassembly 11 in which the sensor element 3 is correctly positioned in the holder 7. The measuring body 13 is enclosed at its rear end by the holder 7. The measuring body 13 extends in the axial direction. A change in position is prevented by the dimensions of the measuring body 13 and the holder 7.

[0042] Fig. Figure 7 shows a subassembly 11 in which the sensor element 3 is not correctly positioned in a holder 7. In this case, the measuring body 13 is lifted because the inner diameter of the holder 7 is too large to hold the measuring body 13 in its position.

[0043] As in the Fig. 3, Fig. 4A and Fig. As can be seen further in Figure 4B, the holder 7 has a separating rib 18 arranged between the wires 14 of the sensor element 3. The separating rib 18 is an integral part of the plastic holder 7. The separating rib 18 serves to insulate the wires 14 from each other to prevent short circuits. Furthermore, the separating rib 18 secures the position of the wires 14 during subsequent manufacturing steps. The wires 14 cannot have their own insulation.

[0044] Fig. Figure 8 shows a detail of the front end of subassembly 11 of Fig. 3. The sensor body 3 is positioned at such a distance from the separating rib 18 that mechanical damage, such as breakage of the glass material, caused by the pressure of the separating rib 18 is avoided. The distance D between the sensor body 3 and the separating rib 18 can, for example, be 1.0 mm.

[0045] Fig. Figure 9 shows a first housing part 4 before assembly with a sub-assembly 11 of the temperature sensor 1. Fig. Figure 10 shows a sub-assembly 11 with dimensions corresponding to the first housing part 4 made of Fig. 9 fit. The first housing part 4 and the sub-assembly 11 can be components of the temperature sensor 1. Fig. 3. The first housing part 4 can be a metal housing.

[0046] The first housing part 4 has a neck region 19 that partially accommodates a neck region 20 of the subassembly 11. The neck regions 19, 20 have a smaller diameter in a direction perpendicular to an axial direction than the base bodies 21, 22 of the first housing part 4 and the subassembly 11, respectively.

[0047] The length l1 of the neck section 19 of the first housing part 4 is shorter than the length l2 of the neck section 20 of the subassembly 11. The overall length L1 of the first housing part 4 is slightly longer than the length L2 of the subassembly 11 from the snap connections 16 to the front end of the sensor body 3. This allows the sensor body 3 to reach or almost reach the tip of the first housing part 4, ensuring a fast response time. For example, the response time can be less than 1 s. For example, the lengths l1 = 4 mm, l2 = 13.8 mm, l2 = 6.3 mm, and l3 = 13.6 mm.

[0048] Depending on the installation situation, different shapes and dimensions of the components are possible, as long as the first housing part 4 fits into the holder 7. The locking mechanism can also vary. For example, a screw mechanism is possible instead of a snap connection. The dimensions of the tip of the first housing part 4 can vary depending on the desired response time and high-voltage requirements of the application. Generally, a smaller tip diameter results in a faster response time.

[0049] The snap connections 16 are configured to engage with matching locking areas 26 at the rear end of the first housing part 4. The locking areas 26 are areas that bulge outwards from the base body 21. The snap height and diameter of the metal housing are designed to achieve a secure locking mechanism.

[0050] Fig. Figure 11 shows a subassembly 11 with further electrical insulation provided by a potting material 23. The subassembly 11 can form part of the temperature sensor 1. Fig. 1 and represents a further intermediate step in the manufacture of the temperature sensor 1.

[0051] The potting material 23 fills a space between the wires 14. Preferably, the wires 14 are completely covered by the potting material 23 on their sides facing each other. The wires 14 are thus electrically insulated by the potting material 23.

[0052] The potting compound 23 can be poured into the gap twice to ensure good insulation.

[0053] The first filling can be carried out in such a way that the wire 14 and part of the glass insulation are fixed. The second filling ensures that the wire 14 is completely protected with the potting material 23.

[0054] The potting compound can be poured into the space after the sensor element 3 has been assembled with the holder 7 and before the first housing part 4 is connected to the holder 7. The potting compound 23 also secures the sensor element 3 to the holder 7. The potting compound 23 can be a resin material.

[0055] Fig. Figure 12 shows the temperature sensor 1 with the first housing part 4, which is connected to the subassembly 11. The first housing part 4 is filled with a further potting material 24. This further potting material 24 can be, for example, an epoxy or silicone resin. The further potting material 24 can be a thermally conductive resin with high thermal conductivity. This can improve the response time.

[0056] The additional potting material 24 can be poured into the first housing part 4 before the first housing part 4 is assembled with the holder 7.

[0057] Furthermore, as in connection with Fig. As mentioned in Figure 1, the interface 12 between the first housing part 4 and the holder 7 is covered by a second housing part 6. The second housing part 6 can be a molded component. The second housing part 6 can be made of plastic using injection molding. The second housing part 6 can have a shape adapted to a desired fastening method.

[0058] The Fig. 13 and Fig. Figure 14 shows different forms of the second housing part 6. In Fig. 13 The second housing part 6 has a snap-fit ​​connection for attaching the temperature sensor 1. In Fig. 14 The second housing part 6 has a screw mount for attaching the temperature sensor 1. The temperature sensor 1 of the Fig. 1 is designed for press-fit installation.

[0059] Fig. Figure 15 shows process steps in a method for manufacturing a temperature sensor 1. The temperature sensor 1 of the disclosed embodiments can be manufactured as follows, in particular with the components and subassemblies described above.

[0060] In step 100, a sensor element 3 is provided which has a measuring body 13 connected by wires 14 (see Fig. 5) The sensor element 3 is positioned in a holder 7 (see Fig. 4A, Fig. 4B). The sensor element 3 can be inserted into the holder 7 from the front. The front area 17 may have a longitudinal slot to facilitate positioning.

[0061] After positioning the sensor element 3 in the holder 7, the wires 14 are connected to the electrical leads 9 (step 110). The connection can be made by a joining method such as soldering, splicing, or welding. It is also possible to slide the holder 7 over the insulated electrical leads 9 before connecting it to the sensor element 3, and then to move the holder 7 towards the NTC element 3 to position the subassembly 11.

[0062] A corresponding intermediate state in the manufacturing process after step 110 is in Fig. Figure 16 shows the following. In this state, the holder 7 has been slid over the insulated electrical leads 9 and the sensor element 3 has been connected to the electrical leads 3. The holder 7 is then moved towards the NTC element 3.

[0063] In a further step 120, the space between the wires 14 is filled with a potting material 23 (see Fig. 11). The potting material 23 may be a resin material.

[0064] Back to Fig. In a further step 130, the first housing part 4 is assembled with the holder 7. The first housing part 4 can be assembled by snap-fit ​​connection or another connection method. The first housing part 4 can be filled with further potting material 24, and the front end of the subassembly 11, which includes the sensor element 3 and the holder 7, can be inserted into the potting material 24 (see Figure 15). Fig. 12).

[0065] In a further step 140, the interface between the holder 7 and the first housing part 4 can be covered by a second housing part 6. The second housing part 6 can be a molded component. The second housing part 6 can have fastening means to secure the temperature sensor 1 in its operating position. Reference figures 1 temperature sensor 2 outer casing 3 Sensor element 4 first housing part 5 top 6 second housing part 7 holders 8 Flange area 9 electrical line 10 sealing element 11 Sub-assembly 12 Interface Housing Part / Holder 13 measuring bodies 14 wires 15 rear area 16 Snap connection 17 front area 18 Separating rib 19 Neck area of ​​the first housing part 20 Neck area of ​​the subassembly 21 Base body of the first housing part 22 Basic body of the subassembly 23 Potting compound 24 additional potting materials 25 Interface measuring body / wires 26 Locking area 100-140 process steps d Inner diameter of the front area of ​​the holder b maximum diameter measuring body l Length measuring body D Distance measuring body / separating rib l1 Length of neck area first housing part l2 Length neck area subassembly L1 Total length first housing part L2 Total length subassembly QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] CN 206573231 U

[0003] JP 4892030 B2

[0003]

Claims

[1] Temperature sensor (1) comprising a first housing part (4) and a holder (7) made of plastic, wherein the first housing part (4) is directly connected to the holder (7), and comprising a sensor element (3) comprising a measuring body (13) and electrical wires (14) connected to the measuring body (13), wherein the sensor element (3) is partially arranged in the holder (7). [2] Temperature sensor (1) according to claim 1, wherein the measuring body (13) protrudes from the holder (7) and an interface between the measuring body (13) and the electrical wires (14) is enclosed by the holder (7). [3] Temperature sensor (1) according to one of the preceding claims, wherein the holder (7) has a separating rib (18), the separating rib (18) being arranged between the electrical wires (14). [4] Temperature sensor (1) according to one of the preceding claims, wherein an inner diameter of a front region (17) of the holder (7) is smaller than a maximum diameter (b) of the measuring body (13). [5] Temperature sensor (1) according to one of the preceding claims, wherein the first housing part (4) comprises a metal. [6] Temperature sensor (1) according to one of the preceding claims, wherein the first housing part (4) is connected to the holder (7) by a snap connection. [7] Temperature sensor (1) according to one of the preceding claims, wherein the first housing part (4) is a preformed component and wherein the holder (7) is a preformed component. [8] Temperature sensor (1) according to one of the preceding claims, wherein the holder (7) is partially enclosed by the first housing part (4). [9] Temperature sensor (1) according to one of the preceding claims, comprising a potting material (23) which fills a space between the wires (14). [10] Temperature sensor (1) according to one of the preceding claims, comprising a further potting material (24) that fills a space between the holder (7) and the first housing part (4). [11] Temperature sensor (1) according to one of the preceding claims, comprising a second housing part (6) which encloses an interface between the first housing part (4) and the holder (7), wherein the second housing part (6) is a forming. [12] Method for manufacturing the temperature sensor (1) according to one of the preceding claims, comprising a step (100) of providing the sensor element (3) and the holder (7) and inserting the sensor element (3) into the holder (7). [13] Method according to claim 12, comprising a further step (120) of filling a space between the wires (14) with a potting material (23). [14] Method according to one of claims 12 or 13, comprising the further step (130) of providing a first housing part (4) and joining the first housing part (4) with the holder (7) by means of a locking mechanism. [15] Method according to any one of claims 12 to 14, comprising the further step (140) of covering an interface between the holder (7) and the first housing part (4) by a second housing part (6) in the form of an overmold.

Images