Electronic assembly with thermal fuse, an electric motor and a drive of a motor vehicle

Abstract

An electronic assembly contains a circuit board having a current-conducting current path with two mutually spaced-apart current path ends that form an interruption point and a contact clip bridging the interruption point. The contact clip is manufactured without a preload, as a thermal fuse. The contact clip has a multiple bent, open clip loop and a contact limb making contact with both mutually spaced-apart current path ends using solder. The contact clip further has a fixing limb with a limb end seated in a circuit board opening. The limb end of the fixing limb is oversized relative to a circuit board opening, and a deformation being imparted to the contact clip, with an internal preload being generated.

Claims

1. An electronic assembly, comprising: a circuit board having a current-conducting current path with two mutually spaced-apart current path ends that form an interruption point, said circuit board having a circuit board opening formed therein; a contact clip bridging said interruption point, said contact clip being manufactured without a preload, as a thermal fuse, said contact clip having a multiple bent, open clip loop and a contact limb making contact with both mutually spaced-apart current path ends using solder, said contact clip further having a fixing limb with a limb end seated in said circuit board opening, said limb end of said fixing limb being oversized relative to said circuit board opening, and a deformation being imparted to said contact clip, with an internal preload being generated; and said open clip loop having between said contact limb and said fixing limb, bent loop sections and a middle loop section with at least three bending points, said middle loop section of said open clip loop having a larger section width than said contact limb and/or said fixing limb, wherein said middle loop section of said open clip loop having a punch opening formed therein, said punch opening extending over at least one of said at least three bending points of said middle loop section, said middle loop section projecting over said fixing limb in a deformed/preloaded state such that said punch opening being disposed in a projecting region projecting over said fixing limb.

2. The electronic assembly according to claim 1, wherein said limb end of said fixing limb is pressed into said circuit board opening when said contact clip is preloaded as a result of being deformed.

3. The electronic assembly according to claim 1, wherein said bent loop sections include a loop section facing said fixing limb, said loop section forming a predetermined bending point for deforming said contact clip.

4. The electronic assembly according to claim 1, wherein said fixing limb has an abutment section that rests on said circuit board, and also has a bent limb section having a reduced section width relative to said abutment section, and an end of said bent limb section forms said limb end that is seated in said circuit board opening.

5. The electronic assembly according to claim 1, wherein said fixing limb has an S-shaped bent limb section.

6. The electronic assembly according to claim 5, wherein said S-shaped bent limb section of said fixing limb forms an abutment or bearing surface for an activation tool that generates the deformation of said contact clip.

7. The electronic assembly according to claim 4, wherein said abutment section rests on a solder pad of said circuit board.

8. An electric motor of an adjustment system, comprising: an electronic assembly, containing: a circuit board having a current-conducting current path with two mutually spaced-apart current path ends that form an interruption point, said circuit board having a circuit board opening formed therein; a contact clip bridging said interruption point, said contact clip being manufactured without a preload, as a thermal fuse, said contact clip having a multiple bent, open clip loop and a contact limb making contact with both mutually spaced-apart current path ends using solder, said contact clip further having a fixing limb with a limb end seated in said circuit board opening, said limb end of said fixing limb being oversized relative to said circuit board opening, and a deformation being imparted to said contact clip, with an internal preload being generated; and said open clip loop having between said contact limb and said fixing limb, bent loop sections and a middle loop section with at least three bending points, said middle loop section of said open clip loop having a larger section width than said contact limb and/or said fixing limb, wherein said middle loop section of said open clip loop having a punch opening formed therein, said punch opening extending over at least one of said at least three bending points of said middle loop section, said middle loop section projecting over said fixing limb in a deformed/preloaded state such that said punch opening being disposed in a projecting region projecting over said fixing limb.

9. A drive of a motor vehicle, comprising: an electronic assembly, containing: a circuit board having a current-conducting current path with two mutually spaced-apart current path ends that form an interruption point, said circuit board having a circuit board opening formed therein; a contact clip bridging said interruption point, said contact clip being manufactured without a preload, as a thermal fuse, said contact clip having a multiple bent, open clip loop and a contact limb making contact with both mutually spaced-apart current path ends using solder, said contact clip further having a fixing limb with a limb end seated in said circuit board opening, said limb end of said fixing limb being oversized relative to said circuit board opening, and a deformation being imparted to said contact clip, with an internal preload being generated; and said open clip loop having between said contact limb and said fixing limb, bent loop sections and a middle loop section with at least three bending points, said middle loop section of said open clip loop having a larger section width than said contact limb and/or said fixing limb, wherein said middle loop section of said open clip loop having a punch opening formed therein, said punch opening extending over at least one of said at least three bending points of said middle loop section, said middle loop section projecting over said fixing limb in a deformed/preloaded state such that said punch opening being disposed in a projecting region projecting over said fixing limb.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 is a diagrammatic, perspective view of an electronic assembly with a circuit board that has a current-conducting current path with two mutually spaced-apart current path ends that form a interruption point that is bridged by a one-piece contact clip serving as a thermal fuse according to the invention;

(2) FIG. 2 is a perspective view of the contact clip in a deformed and tensioned state, depicted according to FIG. 1;

(3) FIG. 3 is a perspective view of the contact clip with the thermal fuse in a tripped state, depicted according to FIG. 1;

(4) FIG. 4 is a perspective view of a fixing limb of the contact clip for press-fit fastening into a circuit board opening;

(5) FIGS. 5 to 8 show a side view of the deformation and preloading of the contact clip;

(6) FIG. 9 is a perspective view of a first alternative configuration of the fixing limb, in a representation according to FIG. 4;

(7) FIG. 10 is a perspective view of the assembly with a second alternative configuration of the fixing limb; and

(8) FIG. 11 is a perspective view of the assembly with a third alternative configuration of the fixing limb.

DETAILED DESCRIPTION OF THE INVENTION

(9) Matching parts and sizes are always assigned the same reference numerals in all drawings.

(10) Referring now to the figures of the drawings in detail and first, particularly to FIG. 1 thereof, there is shown an electronic assembly 2 of an electric motor, not otherwise shown, for an adjusting drive of a motor vehicle. The assembly 2 contains a circuit board 4 equipped with non-illustrated electrical parts; a detail of a current path 6 is shown. The current path 6 additionally has a thermal fuse 8. The thermal fuse 8 protects the electric motor from the risk of overheating and fire during operation. If the electric motor overheats, the thermal fuse 8 is tripped, thereby interrupting the flow of current to the electric motor.

(11) The thermal fuse 8 connects the current path ends 6a and 6b, which conduct the motor current, via an interruption point 10 of the current path 6. In the exemplary embodiment of FIG. 1, the interruption point 10 is formed between the current path ends 6a and 6b, in particular by a slot-like recess of the circuit board 4. The thermal fuse 8 is implemented as a contact clip, and will also be referred to as a contact clip hereinafter.

(12) The contact clip 8 is a punched and bent part with a multiple bent, open clip loop 12, which is implemented on the loop end by both a contact limb 14 and a fixing limb 16. As may be seen comparatively clearly in FIGS. 1 to 3, the contact limb 14 extends over the interruption point 10 in the manner of a bridge. In other words, the interruption point 10 between the current path ends 6a and 6b is bridged only by the contact limb 14.

(13) In the (untripped) mounted state, the tab-like contact limb 14 is attached to both the current path end 6a and the current path end 6b, by means of a respective solder connection. The solder joints formed as a result electrically contact the current path ends 6a and 6b via the contact limb 14, and mechanically connect the contact limb 14 to the circuit board 4.

(14) The contact clip 8 is preferably made from a copper material with a tin coating, without preloading, so that the solder connections of the contact limb 14 with the current path ends 6a and 6b may be produced, particularly in an SMD technique. In this case, the dimensioning of the limb or section width of the contact limb 14 is adapted to the strength of the motor current in normal operation. This means that the electrically-generated heating of the contact limb 14 in normal operation is not sufficient to melt the solder joints between the current path ends 6a and 6b.

(15) To realize the fuse function of the contact clip 8, after the contact clip 8 is first mounted on the circuit board without preload, it is deformed in order to generate or produce an internal (mechanical) preload (FIG. 2).

(16) When mounted, by means of the fixing limb 16, the contact clip 8 is mechanically connected to a solder pad 18 via a solder connection. The fixing limb 16 also has a tongue-shaped limb end 20. The limb end 20, shown in greater detail in FIG. 4, may be inserted into a cylindrical circuit board opening 22 in order to fasten the contact clip 8 to the circuit board 4. The limb end 20 in this case has a limb width that is prepared to be at least partially oversized relative to the diameter of the circuit board opening 22. For purpose of attachment, the limb end 20 is pressed into the circuit board opening 22.

(17) In the event that the fuse is tripped and the heat melts the solder joints between the current path ends 6a and 6b and the contact limb 14, as well as the solder joint between the solder pad 18 and the fixing limb 16, the contact limb 14 pivots into a non-contacting position due to the preloading of the contact clip 8 (FIG. 3). Mechanical fixation by the limb end 20 ensures that the contact clip 8 is always held in a defined position on the circuit board 4, even if the fuse is tripped.

(18) The mounting of the contact clip 8 is explained in more detail below, with reference to FIGS. 5 to 8.

(19) As may be seen comparatively clearly in the side views of FIGS. 5 to 8, in this exemplary embodiment the contact clip 8 has substantially four bending points 24a, 24b, 24c, and 24d forming the clip loop 12. The bending points 24a, 24b, 24c, and 24d form substantially five subsections of the clip loop 12, which are also referred to below as loop sections 12a, 12b, 12c, 12d, and 12e. Loop section 12a in this case merges integrally or monolithically into the contact limb 14, and the loop section 12e merges integrally or monolithically into the fixing limb 16. The clip loop 12 has, in each of these transition areas respectively, a bending point that is not further specified, by which the clip loop 12 of the circuit board 4 stands substantially straight up.

(20) When the contact clip 8 is untensioned as shown in FIG. 5, loop sections 12a and 12e are oriented substantially perpendicular to the circuit board 4. The loop sections 12a and 12e are arranged parallel to each other and spaced apart, forming a loop opening that is oriented toward the circuit board 4. The comparatively long loop section 12a transitions into the loop section 12b by means of the substantially right-angled bending point 24a. The loop section 12b, in this case, is oriented parallel to the circuit board 4.

(21) The bending point 24b between the loop sections 12b and 12c has a substantially perpendicular bending angle. As a result, the loop section 12c is oriented substantially parallel to loop sections 12a and 12e. In particular, “bending angle” hereinafter refers to the angle of bending of a bending point. This is the included angle between two adjacent loop sections, wherein in particular the angles within the loop contour of the clip loop 12 are referred to as bending angles.

(22) The bending point 24c between the loop sections 12c and 12d has an obtuse bending angle, i.e., a bending angle between 90° and 180°. As a result, loop section 12d has a tilt or slant relative to the circuit board 4 until it reaches the bending point 24d. The bending point 24d in this case has a reflex bending angle, i.e., a bending angle greater than 180°.

(23) The exemplary embodiment of the contact clip 8 in FIGS. 1 to 4, in this case, has two additional bending points, not further specified, in the region of the loop section 12d; by means of these, in the course of preloading a step-like shoulder is formed that serves as a predetermined bending point. In addition, a slot-like punch opening 26 is inserted into the clip loop 12. As may be seen in particular in FIGS. 1 to 3, the punch opening 26 extends substantially from the loop section 12c, via the bending point 24b, the loop section 12d and the bending point 24c, to the loop section 12d.

(24) Loop sections 12a and 12e form a bent section of the clip loop 12, and the loop sections 12b, 12c and 12d substantially form a middle section or region of the clip loop 12 arranged between these sections. As may be seen in FIGS. 1 to 3, this middle section has a greater width relative to the contact limb 14 and fixing limb 16. The punch opening 26 is introduced in the area of this increased section width.

(25) The fixing limb 16 has an abutment section 16a that is fastened to the solder pad 18, and also has a bent limb section 16b. The limb section 16b has—as shown in particular in FIGS. 1 to 4—a reduced section or limb width relative to the abutment section 16a. The limb section 16b turns into the limb end 20 on the free end side. The limb section 16b in this case has a substantially S-shaped bending contour between the abutment section 16a and the limb end 20.

(26) During mounting, a deformation is imparted to the contact clip 8 by generating or producing an internal preload (spring preload) by means of an activation tool or a punch 28 (FIG. 6, FIG. 7). During deformation, the bending point 24d serves as a predetermined bending point of the contact clip 8.

(27) As shown in FIGS. 7 and 8, the bending angle of the bended part 24d is bent to a reflex angle of about 270 degrees, so that the loop section 12d is oriented substantially parallel to the circuit board 4. In the course of deformation, the bending point between the loop section 12a and the contact limb 14 is bent in such a way that the loop section 12a extends at an oblique angle with respect to the circuit board 4.

(28) During the deformation or preloading process, and preferably simultaneously, the end 20 of the fixing limb 16 is pressed into the circuit board opening 22 and thus fastened therein during the final assembly (FIG. 8), particularly in the manner of a press fit. For this purpose, the punch 28 presses on a horizontal S-limb of the limb section 16b that is spaced from the circuit board 4. In other words, the horizontal S-limb acts as an abutment or bearing surface 16c for the punch 28. The punch 28 deforms the limb section 16b in such a way that the S-shaped contour of the limb section 16b is compressed or pressed together (FIG. 7). As a result, the limb end 20 is simultaneously pressed into the circuit board opening 22.

(29) For mounting the contact clip 8, the punch 28 substantially has a first punch area 28a for deforming and preloading the clip loop 12 and a second, extension-type punch area 28b for deforming the fixing limb 16 and simultaneously pressing the limb end 20 into the circuit board opening 22. When the clip loop 12 is deformed, it is bent in such a way that the loop sections 12b, 12c and 12d at least partially overlap the fixing limb 16 and the punch opening 26 is disposed in a projection region 40 projecting over the fixing limb 16. The punch opening 26 serves as a recess for the punch area 28b, so that the punch area reliably acts on the fixing limb 16. In other words, as shown in FIG. 7, the punch area 28b is at least partially located within the punch opening 26 of the clip loop 12. This means that the punch opening 26 provides a clearance for the activation tool 28, which is advantageous for mounting.

(30) In the exemplary embodiment of FIG. 9, an alternative configuration is shown of the fixing limb 16 and the limb end 20′ when pressed into the circuit board opening 22. In this exemplary embodiment, the limb end 20′ is, in geometrical terms, designed substantially as an obtuse arrowhead. The limb end 20′, which is shaped roughly like the tip of the arrow, in this case has two inclined outer sides or vanes 30 that extend from the obtuse tip to a tip base 32. The tip base 32 in this case is oversized relative to the circuit board opening 22 for the press-fit attachment.

(31) FIGS. 10 and 11 show two further configurations of the fixing limb 16, with the contact clip 8 in a partially assembled state. In these exemplary embodiments, the circuit board opening 22 is bordered at least partially by the solder pad 18.

(32) In the exemplary embodiment of FIG. 10, the fixing limb 16 has a widened abutment surface 16c for the punch section 28a. This simplifies the pressing of the limb end 20 into the circuit board opening 22. In this case, a punch opening 34 is introduced into the abutment surface 16c.

(33) The exemplary embodiment of FIG. 11 shows a fixing limb 16 with a limb end 20, which has two punch tabs 36 that protrude circumferentially in the region of the abutment surface 16c. The limb end 20 thus has a substantially T-shaped configuration, with the punching tabs 36 forming the horizontal limb of the T and the shaft that may be pressed into the circuit board opening 22 forming the vertical limb of the T. The punch tabs 36 improve the effect of force when pressing into the circuit board opening 22. In this way, the ability to fold the approximately S-shaped limb section 16b during mounting is improved.

(34) The invention is not limited to the above-described exemplary embodiments. Rather, other variants of the invention may also be derived therefrom by a person of ordinary skill in the art, without departing from the subject matter of the invention. In particular, all the individual features described in connection with the exemplary embodiments may also be combined with each other in other ways, without departing from the subject matter of the invention.

(35) The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: 2 Assembly 4 Circuit board 6 Current path 6a, 6b Current path end 8 Thermal fuse/contact clip 10 Interruption point 12 Clip loop 12a, 12b, 12c, 12d, 12e Loop section 14 Contact limb 16 Fixing limb 16a Abutment section 16b Limb section 16c Abutment surface, bearing surface 18 Solder pad 20, 20′ Limb end 22 Circuit board opening 24a, 24b, 24c, 24d Bending point 26 Punch opening 28 Activation tool/punch 28a, 28b Punch area 30 Vane/outer side 32 Tip base 34 Punch opening 36 Punch tab