WO2015096018A1

WO2015096018A1 - Modularized Speed Sensor

Info

Publication number: WO2015096018A1
Application number: PCT/CN2013/090271
Authority: WO
Inventors: Kenichi Ninomiya; Andreas Fink; Desheng ZHAO; Mirko Scheer; Anwar Hegazi
Original assignee: Bosch Automotive Products (Suzhou) Co., Ltd.
Priority date: 2013-12-24
Filing date: 2013-12-24
Publication date: 2015-07-02
Also published as: CN112964891A; CN105452874A; DE112013007708T5

Abstract

A modularized speed sensor is disclosed, which includes a sensor module having a first casing, a speed sensing element disposed in the first casing, and a sensor terminal extending from the speed sensing element; and a cable module having a second casing and a cable having a front end disposed in the second casing; wherein the sensor module and the cable module are formed separately and then assembled to each other directly or indirectly, and contact-type electric connection between the sensor terminal and the cable is established when the sensor module and the cable module are assembled together.

Description

Modularized Speed Sensor

Technical Field

The invention relates to a speed sensor having a modularized assembling structure. Background Art

A typical wheel speed sensor generally comprises a sensor portion and a cable portion attached to the sensor portion, the sensor portion having a leadframe based ASIC (application specific integrated circuit) package which is electrically connected with a two-wire cable of the cable portion. Customized application to a vehicle and isolation of electric components by a thermoplastic or thermosetting polymer are usually realized by an encapsulation which is formed by direct injection or modularized injection, by which the sensor portion and the cable portion are assembled together. A transmission pattern between the expensive ASIC and the cable is necessary.

In the injection process, the encapsulation is usually fixed to a holder portion. Sealing between the encapsulation and the holder portion is effected via small rib geometry of the holder portion, and the rib geometry is melted under the temperature of the injected plastic, forming form fit and material locking between the encapsulation and the holder portion.

Sealing between the cable and the encapsulation is achieved by a combination effect of surface adhesion with slight melting in the injection process and shrinkage in the cooling stage after injection.

Electric connection between the ASIC leadframe and the cable is effected by welding, such as laser welding or ultrasonic welding, or by crimping the terminals of the cable to conductors extending from the leadframe, or by directly welding the wires to the leadframe.

Disadvantages accompanied with the above mentioned sensor structure comprise long process cycle which is mainly resulted from the cooling time of the plastic encapsulation, complex handling of wires during the whole process, and high variance in geometries of ASICs or leadframes depending on mounting locations of sensors in vehicles. In the sealing area of the cable, a thermal process window shall be followed in designing, processing and molding. Specifically, on one hand, shape stability of the cable in the injection mold and clamping effect by cooling must be guaranteed, and on the other hand, sufficient heat shall be inputted from the encapsulation so that the cable is welded by melting at its surface area with the encapsulation. However, it is difficult for current sensor designs to meet the above requirements in different applications and molding conditions (like shrinking differences, different injection points, different injection machines, and different cooling patterns), and increased cost on test and/or additional measures may be unavoidable.

In addition, for forming encapsulations by injection of thermoplastic materials for ASICs with different geometries, depending on applications and mounting requirements of sensors in vehicles, each variant needs new design and process for avoiding thermal and mechanical stresses on the ASIC during injection molding, which also results in increasing of cost.

Summary of the Invention

An object of the invention is to provide a completely new process chain to solve at least some of the disadvantages existed in current speed sensors.

For this end, according to an aspect of the invention, there provides a modularized speed sensor which comprises: a sensor module comprising a first casing, a speed sensing element disposed in the first casing, and a sensor terminal extending from the speed sensing element; and a cable module comprising a second casing, a cable having a front end disposed in the second casing, and a conductive connecting member electrically connected with the cable, wherein the sensor module and the cable module are formed separately and then assembled to each other directly or indirectly, and contact-type electric connection between the sensor terminal and the connecting member is established by assembling the sensor module and the cable module together.

According to an embodiment of the invention, the cable module further comprises a conductive connecting member carried by the second casing and electrically connected with the front end of the cable.

According to an embodiment of the invention, the sensor terminal and the connecting member come into electrically contact with each other when the sensor module and the cable module are assembled together, and an radial elastic force and/or an axial elastic force is created by elastic deformation of at least one of the sensor terminal and the connecting member to keep the contacting state therebetween.

According to an embodiment of the invention, the connecting member is fixed to a wire terminal of the cable during cable manufacturing stage by welding, crimping, or elastic clamping.

According to an embodiment of the invention, the sensor module and the cable module are fixed to each other in a plug-in action, by means of which action, form fit and/or force fit is formed between the first and second casings.

According to an embodiment of the invention, the sensor module and the cable module are provided with standardized mechanical and/or electrical interfaces for facilitating mechanical and/or electrical coupling therebetween.

According to an embodiment of the invention, the modularized speed sensor further comprises a holder module attached to at least one of the sensor module and the cable module, the holder module being configured for fixing the speed sensor to a supporting part for carrying the speed sensor.

According to an embodiment of the invention, the holder module is formed of a plastic material by injection molding onto one of the first and second casings.

According to an embodiment of the invention, the holder module is additionally fixed to the one of the first and second casings by welding or by using an additional fixing member.

According to an embodiment of the invention, the holder module is assembled to the other of the first and second casings in a plug-in action, by means of which action, form fit and/or force fit is formed between the holder module and the other of the first and second casings.

According to an embodiment of the invention, the holder module and the other of the first and second casings are provided with standardized mechanical interfaces for facilitating the mechanical coupling therebetween. In this case, the sensor module and the cable module may be provided with standardized electrical interfaces for facilitating electrical coupling therebetween. According to an embodiment of the invention, at least one of the sensor module, the cable module and the holder module, if any, is standardized.

According to the invention, at least the sensor module and the cable module of the speed sensor are pre-fabricated separately and then assembled together, so that various sensors can be formed by simply assembling the sensor and cable modules, which results in reduction in cost. Meanwhile, molds can be simplified and process cycles can be shortened.

Brief Description of the Drawings

Figure 1 is a schematic sectional view of a sensor module of a speed sensor according to a basic concept of the invention;

Figure 2 is a schematic sectional view showing a state before assembling the sensor module to a cable module;

Figure 3 is a schematic sectional view showing the sensor module and the cable module in an assembled state;

Figures 4 and 5 are schematic cross-sectional views showing possible connection manners between a connecting member and a cable terminal;

Figure 6 is a schematic sectional view of a speed sensor according to a preferred embodiment of the invention;

Figure 7 is a sectional view of a speed sensor according to another preferred embodiment of the invention; and

Figure 8 is a right side view of the speed sensor of Figure 7. Detailed Description of Preferred Embodiments

Now some preferred embodiments of the invention will be described with reference to the drawings.

According to a basic concept of the invention, there provides a wheel speed sensor which comprises a sensor module and a cable module, which are formed as separate units and then assembled together. Figure 1 shows a schematic structure of a sensor module 10 of the invention, which mainly comprises an ASIC chip 1 carried by a leadframe (not shown), a sensor terminal 2 extending from the leadframe for power and signal transmission, and a first casing 3 formed of an insulative plastic material, sealing the ASIC chip 1, the leadframe and an inner part of the sensor terminal 2 therein.

The leadframe may be in the shape of a lattice formed of a sheet metal by punching, the sensor terminal 2 being formed at the same time.

Electric connection between the ASIC chip 1 and the sensor terminal 2 can be achieved by crimping, by an elastic force, or by any other suitable contacting connections.

The first casing 3 may be formed by injection molding or low pressure casting a thermoplastic material, by compression molding a thermosetting material, or by using a sealing machine.

The sensor module 10 is configured so that its reading surface is located with respect to an encoder disc in a specific orientation (side read, bottom read, or slant). For a steel wheel, a permanent magnet is used in the sensor module 10.

As shown in Figure 2, the sensor module 10 can be assembled to a cable module 20 by a plug-in action. The cable module 20 comprises a cable 4 which includes at least one wire 5 with a wire terminal 6, a connecting member 7 electrically connected with the wire terminal 6, and a second casing 8 sealing therein the connecting member 7 and an end portion of the cable 4 connected to the connecting member.

The sensor module 10 and the cable module 20 are assembled together by mating structures provided on their casings. For example, in the embodiment shown in Figure 2, the second casing 8 is formed with a recess for receiving a portion of the first casing 3, forming form fit and/or force fit therewith. Alternatively, the first casing 3 may be formed with a recess for receiving a portion of the second casing 8. Locking features, such as a compression joint, may be formed on the two casings for locking them together in the assembled state shown in Figure 3. Alternatively or additionally, the sensor module 10 may be fixed to the cable module 20 by injection molding, by gluing or by welding, such as laser welding, laser jet welding or ultrasonic welding. Still alternatively or additionally, an additional fastening member may be used for locking the sensor module 10 to the cable module 20. Sealing between the two casings may be effected by a sealing member, rib-groove mating structures, a sealing agent, or the like.

The connecting member 7 is formed of a conductive sheet metal, and is fixed to the wire terminal 6 in cable manufacturing stage by welding, by crimping, by an elastic force, or by any other suitable means. As shown in Figure 4, in an embodiment of the invention, a portion 7' of the connecting member 7 is crimped onto the wire terminal 6, forming contact-type electric connection therebetween. As shown in Figure 5, in another embodiment of the invention, the wire terminal 6 is elastically deformed within the connecting member 7, forming contact- type electric connection therebetween by means of radial elastic forces created by the deformation of the wire terminal 6. Alternatively or additionally, contact-type electric connection between the wire terminal 6 and the connecting member 7 may be established by means of an axial elastic force created by elastic deformation of the wire terminal 6 and/or the connecting member 7.

Under the restriction of the second casing 8, the shape of the connecting member 7 and the position of the connecting member 7 with respect to the cable 4 are fixed, and the insulation of them from environment is achieved.

When the sensor module 10 is assembled to the cable module 20, the sensor terminal 2 comes into contact with the connecting member 7, for example, by inserted into the connecting member 7, forming electric connection therebetween by means of an elastic force (in radial, axial, or both directions) created by elastic deformation of the sensor terminal 2 and/or the connecting member 7.

In vehicle applications, the speed sensor is fixed to a part of the vehicle. For this end, a holder module is added to the assembly of the sensor module 10 and the cable module 20. The holder module is preferably formed of a plastic material and is attached to either or both of the casings of the sensor module 10 and the cable module 20.

In an embodiment shown in Figure 6, a speed sensor comprises a sensor module 10, a cable module 20 and a holder module 30. The sensor module 10 has a first casing 3, and the cable module 20 has a second casing 8 and a cable 4 fixed at its front end in the second casing 8. The second casing 8 comprises a front part 8a which is inserted and fixed into the first casing 3 and a back part 8b onto which the holder module 30 is attached.

In this embodiment, the holder module 30 is formed onto the second casing 8 by over-molding. The holder module 30 comprises a tubular portion 11 surrounding the back part 8b and a flange- shaped fixing portion 12 extending radially outwardly from the tubular portion 11. Fixing features, such as clampers, through holes to be passed through by screws and the like, may be formed on/in the fixing portion 12 for fixing the speed sensor to a part of the vehicle.

A sealing member may be carried by the fixing portion 12 for sealing the speed sensor to the part of the vehicle.

Locking features, like one or more circumferential grooves 13, may be formed on the back part 8b and cooperate with the material of the tubular portion 11 for fixing the holder module 30 to the cable module 20. Alternatively or additionally, the tubular portion 11 is welded to the back part 8b at welding points 14.

In an embodiment shown in Figures 7 and 8, a speed sensor comprises a sensor module 10, a cable module 20 and a holder module 30. The sensor module 10 comprises a first casing which consists of a first part 3a and a second part 3b assembled to each other and which defines an internal space therein, a sensing element disposed in the internal space, and a pair of sensor terminals 2a and 2b, for power and signal transmission respectively, extending from the sensing element through the second part 3b and exposed at the back end of the second part 3b.

The cable module 20 comprises a second casing 8, a cable 4 sealed at its front end in the second casing 8, and a connecting member fixed to the front end of the second casing 8 and connected with two wires in the cable 4, the connecting member having connecting terminals 7a and 7b to be electrically contacting connected with the sensor terminals 2a and 2b respectively.

The holder module 30 comprises a first tubular portion 11a assembled to the second part 3b of the first casing, a second tubular portion lib assembled to the second casing 8, a fixing portion 12' protruded from the joint between the first and second tubular portions 11a and lib in a radially outward direction, and a reinforcing member 15 disposed in the fixing portion 12', the reinforcing member 15 comprising a through hole 16 to be passed through by a screw for fixing the whole sensor to a part of the vehicle. The reinforcing member 15 is preferably made of a material which has a higher strength than the plastic material forming the remaining portions of the holder module 30. The holder module 30 may be attached to the sensor module 10 and the cable module 20 by locking structures, by welding, or by over-molding.

In the embodiment shown in Figures 7 and 8, there is no mechanical coupling/sealing between the casings of the sensor module 10 and the cable module 20; however, form fit and/or force fit may be provided therebetween in other embodiments.

According to the invention, the sensor module 10 and the cable module 20 of the speed sensor are pre-fabricated and then assembled together directly or by means of another member (like the holder module 30), so that various sensors can be formed by simply assembling the sensor and cable modules for different applications or mounting locations in vehicles. Variable assembling patterns are effected in an easy way.

All the modules can be standardized, thus only reduced number of parts and molds are needed.

Electric connection between the ASIC chip and the cable is effected by a mechanical plug-in step in a simplified assembling line.

Standardized interfaces may be provided on modules for facilitating the assembly therebetween.

The holder module may be formed on one of the sensor and cable modules by an injection process with simplified molds and shortened process cycles, thus the thermal process window is broadened.

The holder module is preferably formed on the cable module by injection molding (over- molding), so that the internal components of the sensor module are less affected by the injection.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. The attached claims and their equivalents are intended to cover all the modifications, substitutions and changes as would fall within the scope and spirit of the invention.

Claims

1. A modularized speed sensor comprising: a sensor module comprising a first casing, a speed sensing element disposed in the first casing, and a sensor terminal extending from the speed sensing element; and a cable module comprising a second casing and a cable having a front end disposed in the second casing; wherein the sensor module and the cable module are formed separately and then assembled to each other directly or indirectly, and contact-type electric connection between the sensor terminal and the cable is established when the sensor module and the cable module are assembled together.

2. The modularized speed sensor of claim 1, wherein the cable module further comprises a conductive connecting member carried by the second casing and electrically connected with the front end of the cable.

3. The modularized speed sensor of claim 2, wherein the sensor terminal and the connecting member come into electrically contact with each other when the sensor module and the cable module are assembled together, and an radial elastic force and/or an axial elastic force is created by elastic deformation of at least one of the sensor terminal and the connecting member to keep the contacting state therebetween.

4. The modularized speed sensor of claim 2 or 3, wherein the connecting member is fixed to a wire terminal of the cable during cable manufacturing stage by welding, crimping, or elastic clamping.

5. The modularized speed sensor of any one of claims 1 to 4, wherein the sensor module and the cable module are fixed to each other in a plug-in action, by means of which action, form fit and/or force fit is formed between the first and second casings.

6. The modularized speed sensor of claim 5, wherein the sensor module and the cable module are provided with standardized mechanical and/or electrical interfaces for facilitating mechanical and/or electrical coupling therebetween.

7. The modularized speed sensor of any one of claims 1 to 4, further comprising a holder module attached to at least one of the sensor module and the cable module, the holder module being configured for fixing the speed sensor to a supporting part for carrying the speed sensor.

8. The modularized speed sensor of claim 7, wherein the holder module is formed of a plastic material by injection molding onto one of the first and second casings.

9. The modularized speed sensor of claim 8, wherein the holder module is additionally fixed to the one of the first and second casings by welding or by using an additional fixing member.

10. The modularized speed sensor of claim 8 or 9, wherein the holder module is assembled to the other of the first and second casings in a plug-in action, by means of which action, form fit and/or force fit is formed between the holder module and the other of the first and second casings.

11. The modularized speed sensor of claim 10, wherein the holder module and the other of the first and second casings are provided with standardized mechanical interfaces for facilitating the mechanical coupling therebetween.

12. The modularized speed sensor of claim 11, wherein the sensor module and the cable module are provided with standardized electrical interfaces for facilitating electrical coupling therebetween.

13. The modularized speed sensor of any one of claims 1 to 12, wherein at least one of the sensor module, the cable module and the holder module, if any, is standardized.