WO2019041224A1

WO2019041224A1 - Polymeric positive temperature coefficient device for seat motor protection

Info

Publication number: WO2019041224A1
Application number: PCT/CN2017/099907
Authority: WO
Inventors: Jianming BU; Yan Fang; Cheng Hu
Original assignee: Littelfuse Electronics Shanghai Co Ltd
Current assignee: Littelfuse Electronics Shanghai Co Ltd
Priority date: 2017-08-31
Filing date: 2017-08-31
Publication date: 2019-03-07
Anticipated expiration: 2020-02-29
Also published as: CN109729736A; CN109729736B

Abstract

L'invention concerne un dispositif à coefficient de température positif (PTC) comprenant un composant de protection (102), tel qu'une puce PTC polymère, une première borne (108) et une seconde borne (110) couplées à des côtés opposés du composant de protection (102). Le dispositif PTC comprend en outre un boîtier de composant (106) enveloppant le composant de protection (102) et les bornes (108, 110), le boîtier de composant (106) comprenant une première extrémité (114) et une seconde extrémité (116), et les première et seconde bornes (108, 110) s'étendant à travers une paroi d'extrémité (144) de la seconde extrémité (116). Chacune des première et seconde bornes (108, 110) comprend un corps principal (156) et un bras de borne (158) s'étendant à partir du corps principal (156), le bras de borne (158) s'étendant à travers la paroi d'extrémité (144) d'une extrémité fermée du boîtier de composant (106), et le corps principal (156) étant enveloppé par le boîtier de composant (106).Provided is a positive temperature coefficient (PTC) device comprising a protection component (102), such as a polymer PTC chip, a first terminal (108) and a second terminal (110) coupled to opposite sides of the protection component (102). The PTC device further comprises a component housing (106) enclosing the protection component (102) and the terminals (108, 110), the component housing (106) having a first end (114) and a second end (116). ), and the first and second terminals (108, 110) extending through an end wall (144) of the second end (116). Each of the first and second terminals (108, 110) includes a main body (156) and a terminal arm (158) extending from the main body (156), the terminal arm (158) extending through the end wall (144) of a closed end of the component housing (106), and the main body (156) being enveloped by the component housing (106).

Description

POLYMERIC POSITIVE TEMPERATURE COEFFICIENT DEVICE FOR SEAT MOTOR PROTECTION

Field of the Disclosure

The disclosure relates generally to seat motor protection， and more particularly， to a polymeric positive temperature coefficient (PPTC) device including an encapsulated PPTC chip for seat motor protection.

Background of the Disclosure

Locked rotor often happens in motor working， it will increase current rapidly then generate the heating to cause high temperature issue. Motor are used in auto industrial like for auto seat， window lifting and others. In order to provide an over-temperature or over-current protection for an auto seat motor， various protection devices have been developed. One such protection device includes a positive temperature coefficient (PTC) device， which may contain PTC elements such as a PTC conductive polymer， e.g.， a composition comprising an organic polymer and， dispersed or otherwise distributed therein， a particulate conductive filler， e.g. carbon black， or a metal or a conductive metal compound. Such devices may be referred to as polymeric PTC， or PPTC resistors or resistive devices. However， these protection devices fail to sufficiently insulate the protection component from damage.

Summary

In view of the foregoing， what is needed is a protection device for fault protection， wherein the protection device is arranged within a component housing so as more fully encapsulate a PTC component housed therein.

In one approach， a positive temperature coefficient (PTC) device includes a protection component， a first terminal electrically connected to a first side of the protection component， and a second terminal electrically connected to a second side of the protection component. The PTC device may further include a component housing surrounding the protection component， the first terminal， and the second terminal， wherein the component housing includes a first end and a second end， and wherein the first and second terminals extend through an end wall of the second end.

In another approach， a polymeric positive temperature coefficient (PPTC) device includes a PPTC chip， a first terminal physically coupled to a first side of the PPTC chip， and a second terminal physically coupled to a second side of the PPTC chip. The PPTC device may further include a component housing surrounding the PPTC chip， the first terminal， and the second terminal， wherein the component housing includes a first end and a second end， and wherein the first and second terminals extend through an end wall of the second end.

In yet another approach， a method may include providing a protection assembly including a protection component disposed between a set of terminals， wherein a first terminal of the set of terminals is physically coupled to a first side of the protection component， and wherein a second terminal of the set of terminals is physically coupled to a second side of the protection component. The method may further include surrounding the protection assembly with a component housing， wherein the component housing includes a first end and a second end， and wherein the first and second terminals extend through an end wall of the second end.

Brief Description of the Drawings

The accompanying drawings illustrate exemplary approaches of the disclosed embodiments so far devised for the practical application of the principles thereof， and in which：

FIG. 1 is an isometric view of a device， such as a PTC device， according to exemplary approaches of the disclosure；

FIG. 2 is another isometric view of the PTC device of FIG. 1 according to exemplary approaches of the disclosure；

FIG. 3 is side cross-section view of the PTC device of FIG. 1 according to exemplary approaches of the disclosure；

FIG. 4 is an exploded view of a protection assembly of the PTC device of FIG. 1 according to exemplary approaches of the disclosure；

FIG. 5 is a perspective view of the protection assembly of FIG. 4 according to exemplary approaches of the disclosure；

FIG. 6 is an isometric view of another PTC device according to exemplary approaches of the disclosure； and

FIG. 7 depicts a process flow for forming a PTC device according to exemplary approaches of the disclosure.

The drawings are not necessarily to scale. The drawings are merely representations， not intended to portray specific parameters of the disclosure. The drawings are intended to depict typical embodiments of the disclosure， and therefore should not be considered as limiting in scope. In the drawings， like numbering represents like elements.

Furthermore， certain elements in some of the figures may be omitted， or illustrated not-to-scale， for illustrative clarity. Furthermore， for clarity， some reference numbers may be omitted in certain drawings.

Detailed Description

Embodiments in accordance with the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings. The system/circuit may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather， these embodiments are provided so that this disclosure will be thorough and complete， and will fully convey the scope of the system and method to those skilled in the art.

For the sake of convenience and clarity， terms such as ″top， ″ ″bottom， ″ ″upper， ″ ″lower， ″ ″vertical， ″ ″horizontal， ″ ″lateral， ″ and ″longitudinal″ will be used herein to describe the relative placement and orientation of various components and their constituent parts. Said terminology will include the words specifically mentioned， derivatives thereof， and words of similar import.

As used herein， an element or operation recited in the singular and proceeded with the word ″a″ or ″an″ should be understood as not excluding plural elements or operations， unless such exclusion is explicitly recited. Furthermore， references to ″one embodiment″ of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

Provided herein is a positive temperature coefficient (PTC) device including a protection component， such as a polymeric PTC chip， and first and second terminals coupled to opposite sides of the protection component. The PTC device further includes a component housing surrounding the protection component and terminals， wherein the component housing includes a first end and a second end， and wherein the first and second terminals extend through an end wall of the second end. In some embodiments， each of the first and second terminals includes a main body and a terminal arm extending from the main body， wherein the terminal arm extends through the end wall of a closed end of the component housing， and wherein the main body is enclosed by the component housing.

In some approaches， the protection component is a passive protection component， such as a PTC chip， a negative temperature coefficient (NTC) chip， or a fuse. In other approaches， the protection component may include active protection components such as integrated circuits or sensors. The protection component may be embedded in a component housing made of a flexible material or molding， or a coating or encapsulation， such as epoxy. The active and/or passive components may be connected with a conductive layer to form a protection circuit with a set of terminals.

In some embodiments， the device is divided into multiple layers， namely a top layer， a central layer， and a bottom layer. For example， the top layer includes afirst terminal， the central layer embeds and encapsulates the protection component (s) ， as well as contains one or more soldering layers， and the bottom layer includes a second terminal. The first and second terminals， or lands， may be connected to external circuits or external equipment， such as lead wires in a motor box， thus offering component protection.

As a result， embodiments of the present disclosure may provide at least the following advantages. Firstly， auto seat motor fault protection is achieved， while corrosion or damage to the fault protection element is minimized. Secondly， by virtue of the auto seat motor fault protection device being arranged within the component housing of the device， variation of cell parameters such as current， condition and temperature of electrolyte can be directly sensed， thus making auto seat fault protection more safe and reliable. Thirdly， when a thermal cut off (TCO) or PTC chip is employed， the PTC device can be reused to achieve repeatable protection.

Turning now to FIGS. 1-3， illustrated is an exemplary PTC device (hereinafter ″device″ ) 100 in accordance with embodiments of the present disclosure. As shown， the device 100 may include a protection component 102， such as a PTC chip， sandwiched between a first terminal 108 and a second terminal 110. Together， the protection component 102， the first terminal 108， and the second terminal 110 form a protection assembly 112， which is encased within a component housing 106. Once joined， the protection component 102， the first terminal 108， and the second terminal 110 form a protection circuit used to detect and mitigate the occurrence of a fault condition.

In some embodiments， the protection component 102 is the primary component for achieving fault protection. The protection component 102 may include a thermal cut off (TCO) element， a thermal fuse or a positive temperature coefficient (PTC) circuit protection component. According to some embodiments， the PTC circuit protection component may be a polymeric positive temperature coefficient (PPTC) circuit protection component. When a TCO or PTC circuit protection component is employed， the device 100 can be reused and achieve repeatable protection.

The protection component 102 may have any shape suitable for connection with the first and

second terminals

108， 110 and for arrangement within the component housing 106. According to other embodiments， the protection component 102 may be designed as a tape or as a chip-type element. When designed as a tape， the protection component 102 may have a width of about 1mm to 5mm， and a thickness of about 0.2mm to 2mm. However， the protection component 102 may take on other lengths， shapes， and/or sizes in other embodiments.

In some embodiments， the protection component 102 is selected from the non-limiting group consisting of： fuses， PTCs， NTCs， ICs， sensors， MOSFETS， resistors， and capacitors. Of these protection components， ICs and sensors are considered to be active protection components， while PTCs， NTCs， and fuses are considered to be passive components. In the embodiment shown， the protection component 102 may be a PPTC chip. It will be appreciated， however， that the embodiments described herein are not limited to any number or particular type of protection component.

Furthermore， the PTC material of protection component 102 may be made of a positive temperature coefficient conductive composition comprising a polymer and a conductive filler. The polymer of the PTC material may be a crystalline polymer selected from the group consisting of polyethylene， polypropylene， polyoctylene， polyvinylidene chloride and a mixture thereof. The conductive filler may be dispersed in the polymer and is selected from the group consisting of carbon black， metal powder， conductive ceramic powder and a mixture thereof. Furthermore， to improve sensitivity and physical properties of the PTC material， the PTC conductive composition may also include an additive， such as a photo initiator， cross-link agent， coupling agent， dispersing agent， stabilizer， anti-oxidant and/or nonconductive anti-arcing filler.

As further shown， the device 100 may include the component housing 106 encasing the protection assembly 112. In some embodiments， the component housing 106 may include a first end 114， a second end 116， an upper wall 120， a bottom wall 122， and a pair of sidewalls 124 extending between the upper wall 120 and the bottom wall 122. In the embodiment shown， the first end 114 is open， while the second end 116 is closed by an end wall 144. During assembly， the protection assembly 112 may be inserted into a cavity 130 of the component housing 106， wherein a tab or protrusion 132 of the protection assembly 112 extends into an opening 136 of the component housing 106 to restrict movement of protection assembly 112 relative to the component housing 106. Insertion and alignment of the protection assembly 112 may be achieved by an interior slot 150 configured to receive/engage the protrusion 132. Once in place， a trailing surface 140 of the protrusion 132 overlaps with an interior edge 142 of the opening 136 to restrict movement of the first terminal 108 and the second terminal 110 towards the first end 114 of the component housing 106. In some embodiments， the protrusion 132 and the opening 136 coupled together in a snap-fit arrangement.

As shown， the first and

second terminals

108， 110 are configured to extend through a set of

openings

148， 149 of the end wall 144. In some embodiments， the

openings

148， 149 are sized to fit closely around each of the first and

second terminals

108， 110 to limit contamination of the protection component 102 within the cavity 130 of the component housing 106. As best shown in FIG. 2， in some embodiments， the

openings

148， 149 may be offset relative to one another. Stated differently， the opening 148 may be located closer to the bottom wall 122， while the opening 149 may be located closer to the upper wall 120. The

openings

148， 149 may be offset relative to one another to compensate for the stacking arrangement of the protection assembly 112.

Although not limited to any particular shape or configuration， the component housing 106 may have a generally rectangular shape. In some embodiments， the component housing 106 is made from an epoxy coating material. In other embodiments， the component housing 106 is made from a moldable material. In exemplary embodiments， the component housing 106 serves as an anti-corrosion sealing element used to prevent the protection component 102 from being eroded， for example， by elements present in a lithium polymer battery electrolyte. To accomplish this， in some particular embodiments， the component housing 106 combines with the first and

second terminals

108， 110 to fully cover the protection component 102.

According to some particular embodiments， the component housing 106 is flexible so that the component housing 106 may conform to the thermal expansion or contraction of the protection component 102 and/or the first and

second terminals

108， 110， thereby ensuring a sealing effect around the protection component 102. According to other embodiments， component housing 106 includes at least one of a heat shrinkable tube， an injection molded article， and a coating film. The material for the heat shrinkable tube may be plastic， including polyvinyl chloride (PVC) ， polypropylene (PP) ， ethylene-vinyl acetate copolymer (EVA) ， polyethylene terephthalate (PET) ， and the like. The material may be extrusion-molded into a plastic tube having a predetermined size and shape， and then the polymer is interlinked by using irradiation technique. The size of the tube is enlarged through a mold， and then the tube shrinks to reach a preset size and shape by means of interlinking the polymer by irradiation under a heating condition， thereby providing an insulation sealing for the component housing 106， and in turn rendering the protected part an anti-corrosion function by isolating it from the external environment.

According to some particular embodiments， the heat shrinkable tube may be a dual wall heat shrinkable tube. The material of outer wall of the dual wall heat shrinkable tube may be semirigid PP， which provides a sufficient strength， and the material of inner wall may be soft PP， which aids with sealing. In the present disclosure， when a dual wall heat shrinkable tube is used， an increased sealing effect on the protection component 102 can be achieved.

In some embodiments， the heat shrinkable tube may include one or more anti-corrosion sealing layers provided on a boundary of the heat shrinkable tube (i.e.， the interface between components covered by the heat shrinkable tube and the part not covered by the heat shrinkable tube) . The material for this anti-corrosion sealing layer may be an anti-corrosion plastic material， including liquid crystal polymer (LCP) ， polybutylene succinate (PBS) ， polyethylene (PE) ， polycarbonate (PC) ， and the like. By sealing the possible open area of the heat shrinkable tube by the anti-corrosion sealing layer， the sealing effect of the anti-corrosion sealing element is further improved.

Referring now to FIGs. 4-5， the protection assembly 112 will be described in greater detail. As shown， the protection assembly 112 includes the protection component 102， the first terminal 108， and the second terminal 110. The first terminal 108 may be directly physically coupled to a top surface 152 of the protection component 102， while the second terminal 110 may be directly physically coupled to a bottom surface 154 of the protection component 102. Each of the first and

second terminals

108， 110 may include a main body 156 and a terminal arm 158 extending from the main body 156. As previously described， each of the terminal arms 158 may extend through the end wall 144 of the component housing 106. In exemplary embodiments， the main body 156 of each terminal 108 and 110 is enclosed by the component housing 106 and is generally sized to extend fully over the main body 156of the protection component 102.

As further shown， the first terminal 108and/or the second terminal 110 may include the protrusion 132 extending from an outer surface 160 of the main body 156， wherein the protrusion 132 is configured to extend through the opening136 of the component housing 106. In some embodiments， the protrusion 132 includes a sloped leading surface 162 and the trailing surface 140， wherein the trailing surface 140 is oriented perpendicular or substantially perpendicular to a plane defined by the outer surface 160 of the main body 156. During insertion， the sloped leading surface 162 eases engagement of the protrusion 132 within the slot 150.

Turning now to FIG. 6， a protection device 200 according to another embodiment of the present disclosure will be described in greater detail. In this embodiment， the component housing 206 may be formed by an injection molding or coating process. For example， the material used in the injection molding process may be an anti-corrosion plastic material， including liquid crystal polymer (LCP) ， polybutylene succinate (PBS) ， polyethylene (PE) ， polycarbonate (PC) ， and the like. According to some particular embodiments， the material used in the coating process may be a curable anti-corrosion material， including some thermal curable resins， such as epoxy resin， polyurethane， acrylic resin， silicone resin， poly (p-xylylene) polymers， and fiuororesin.

The component housing 206 may be molded around or applied as a coating to the protection component 202 after the first and

second terminals

208 and 210 have been coupled to the protection component 202. By doing， a better seal may be formed around the coupling of the protection component 202 and the first and

second terminals

208 and 210. As shown， the component housing 206 extends around the main body (not visible) of each of the first and

second terminals

208 and 210， while the terminal arms 258 extend outwardly through the end wall 244. In this embodiment， the first end 214 of the component housing 206 is also closed so that no openings are provided through the component housing 206 except the set of openings through the end wall 244 for the terminal arms 258.

According to some particular embodiments， in the case the component housing 206 is formed by a coating process， the component housing 206 may include a structure of multiple layers. For example， the component housing 206may include a flexible adhesive coating layer， an oxygen barrier layer， and an anti-corrosion coating layer， in this order， from the inside out. The use of layered component housing 206having multiple coating layers may improve the protection effect on the protection component 202. For example， the main component of the flexible adhesive coating layer may be a silicone resin， which not only assures the bonding force between the component housing 206 and the protection component 202， but also provides a buffering function to reduce the occurrence of inner stress. The main component of the oxygen barrier layer may be an epoxy resin， which is capable of insulating the protection component 202 from the influence of oxidation， such as by oxygen gas and the like. The main component of the outermost anti-corrosion coating layer may be a fluororesin， which provides protection against battery electrolytes. The multiple layered component housing 206 is not limited to a three layers structure， however， and the number of the layers (for example， two layers) and the function of each layer may be selected as desired.

Turning now to FIG. 7， an exemplary process300for providing a protection device will be described in greater detail. First， as shown at block 301， the process 300 includes providing a protection assembly including a protection component disposed between a set of terminals， wherein a first terminal of the set of terminals is physically coupled to a first side of the protection component， and wherein the second terminal of the set of terminals is physically coupled to a second side of the protection component. In some embodiments， the protection component is one of： fuses， PTCs， NTCs， ICs， sensors， MOSFETS， resistors， and capacitors. In some embodiments， the first and second terminals are electrically connected with the protection component via a conductive layer， such as a soldering material.

At block 303， the process 300 may include surrounding the protection assembly with a component housing， wherein the component housing includes a first end and a second end， and wherein the first and second terminals extend through an end wall of the second end. In some embodiments， the component housing encases the protection component. In some embodiments， the component housing may wrap around first and second ends of the protection component， while a set of openings through the first or second end allow exposure of the terminal arms of the terminals. In some embodiments， the component housing may be molded around or applied as a coating to the protection component after the first and second terminals and have been coupled to the protection component.

In some embodiments， the component housing is a case or cover that surrounds a portion of the first and second terminals. In some embodiments， the process 300 may further include inserting the protection assembly into a cavity of the component housing， wherein a protrusion of the protection assembly extends into an opening of the component housing to restrict movement of the protection assembly relative to the component housing. In some embodiments， the process 300 may further include guiding the protrusion along an internal slot in a wall of the component housing as the protection assembly is inserted into the component housing.

In sum， at least the following technical benefits and advantages are offered by embodiments of the present disclosure. Firstly， the PPTC device can be assembled into harsh environments and may be handled more easily. Secondly， encapsulation of the PPTC subassembly helps avoid shorting caused by melting tin dropping on metal components. Thirdly， the encapsulation housing is customizable in size to match customer preferences. For example， only one PTC subassembly type and specification can be applied to different models using encapsulation layer size adjustment. Fourthly， encapsulation with insert molding or epoxy coating process can achieve thinner layers， and the process is easier to reach automatic production， thus achieving lower cost. Fifthly， encapsulation using a plastic housing box permits the PTC device to be snap-fit in place， thus reducing assembly time and cost.

While the present disclosure has been described with reference to certain approaches， numerous modifications， alterations and changes to the described approaches are possible without departing from the sphere and scope of the present disclosure， as defined in the appended claims. Accordingly， it is intended that the present disclosure not be limited to the described approaches， but that it has the full scope defined by the language of the following claims， and equivalents thereof. While the disclosure has been described with reference to certain approaches， numerous modifications， alterations and changes to the described approaches are possible without departing from the spirit and scope of the disclosure， as defined in the appended claims. Accordingly， it is intended that the present disclosure not be limited to the described approaches， but that it has the full scope defined by the language of the following claims， and equivalents thereof.

Claims

A positive temperature coefficient (PTC) device， comprising：

a protection component；

a first terminal connected to a first side of the protection component；

a second terminal connected to a second side of the protection component； and

a component housing surrounding the protection component， the first terminal， and the second terminal， wherein the component housing includes a first end and asecond end， and wherein the first and second terminals extend through an end wall of the second end.
The PTC device of claim 1， wherein the first terminal is directly physically coupled to the first side of the protection component and the second terminal is directly physically coupled to the second side of the protection component.
The PTC device of claim 1， wherein the protection component is a polymeric PTC chip.
The PTC device of claim 1， wherein each of the first and second terminals comprises：

a main body； and

a terminal arm extending from the main body， wherein the terminal arm extends through the end wall of the second end of the component housing， and wherein the main body is enclosed by the component housing.
The PTC device of claim 4， wherein at least one of the first terminal and the second terminal includes a protrusion extending from an outer surface of the main body， and wherein the protrusion extends into an opening of the component housing.
The PTC device of claim 5， wherein the protrusion includes a sloped leading surface and a trailing surface， the trailing surface extending substantially perpendicularly from the outer surface of the main body.
The PTC device of claim 6， wherein the trailing surface overlaps with an interior edge of the opening to restrict movement of the first terminal and the second terminal towards the first end of the component housing.
The PTC device of claim 5， wherein the component housing includes an internal slot configured to engage the protrusion.
The PTC device of claim 1， wherein the first end of the component housing is an open end， and wherein the second end of the component housing is a closed end.
The PTC device of claim 1， wherein the first end is a closed end such that no openings are provided through the component housing except a set of openings for the first and second terminals extending through the end wall of the second end.
A polymeric positive temperature coefficient (PPTC) device， comprising：

a PPTC chip；

a first terminal physically coupled to a first side of the PPTC chip；

a second terminal physically coupled to a second side of the PPTC chip； and

a component housing surrounding the PPTC chip， the first terminal， and the second terminal， wherein the component housing includes a first end and a second end， and wherein the first and second terminals extend through an end wall of the second end.
The PPTC device of claim 11， wherein each of the first and second terminals comprises：

a main body； and

a terminal arm extending from the main body， wherein the terminal arm extends through the end wall of the second end of the component housing， and wherein the main body is enclosed by the component housing.
The PPTC device of claim 12， wherein at least one of the first terminal and the second terminal includes a protrusion extending into an opening of the component housing， the protrusion including a sloped leading surface and a trailing surface， and the trailing surface extending substantially perpendicularly from the main body.
The PPTC device of claim 13， wherein the trailing surface overlaps with an interior edge of the opening to restrict movement of the first terminal and the second terminal towards the first end of the component housing.
The PPTC device of claim 13， the component housing comprising：

an upper wall opposite a bottom wall； and

an internal slot provided in at least one of the upper wall or the bottom wall， the internal slot configured to engage the protrusion as the first terminal and the second terminal are inserted into the component housing.
The PPTC device of claim 11， wherein the first end is a closed end such that no openings are provided through the component housing except a set of openings for the first and second terminals extending through the end wall of the second end.
A method， comprising：

providing a protection assembly including a protection component disposed between a set of terminals， wherein a first terminal of the set of terminals is physically coupled to a first side of the protection component， and wherein a second terminal of the set of terminals is physically coupled to a second side of the protection component； and

surrounding the protection assembly with a component housing， wherein the component housing includes a first end and a second end， and wherein the first and second terminals extend through an end wall of the second end.
The method of claim 17， wherein the component housing is molded around the protection assembly.
The method of claim 17， wherein the protection assembly is inserted into a cavity of the component housing， and wherein a protrusion of the protection assembly extends into an opening of the component housing to restrict movement of protection assembly relative to the component housing.
The method of claim 19， further comprising guiding the protrusion along an internal slot in a wall of the component housing as the protection assembly is inserted into the component housing.