JP2006031955A - Thermal switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal switch preventing deformation of a cover and enabling to form by a resin mold. <P>SOLUTION: The thermal switch is provided with a case 1 of synthetic resin including a housing part 1a with an upper surface opened, first and second fixed terminals 2, 3 arranged in the housing part 1a so that a part of them are exposed, a reversible bimetallic piece 6 housed in the housing part 1a, with one end side connected to the first fixed terminal 2 and with a movable contact 7 fixed on the other end side which contacts with and separates from a fixed contact 3a provided on the second fixed terminal 3, and the cover 8 of synthetic resin overlapped on the case 1 so as to cover the housing part 1a. A deformation preventing part 9 of metal, which can withstand a resin flow pressure in forming the case 1 and the cover 8 by the resin mold, is formed on the cover 8. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thermally responsive switch, and more particularly to a structure of a thermally responsive switch that opens and closes an electrical contact by reversing a movable contact by the thermal response of a bimetal piece.

  The structure of the conventional thermal responsive switch consists of a movable contact that is made of a thermally responsive element (bimetal) made by bonding together multiple metals with different coefficients of thermal expansion, a movable contact provided on the bimetal piece, and a normally closed contact with this movable contact. The thing of the structure which consists of a fixed contact which comprises a circuit is known (for example, refer patent document 1).

Hereinafter, the structure of a conventional thermally responsive switch will be described with reference to the drawings.
FIG. 6 is a perspective view showing a conventional thermal response switch, and FIG. 7 is a cross-sectional view showing the conventional thermal response switch.

  In the figure, the insulating case 31 is formed in a box shape whose upper surface is opened with an insulating material such as synthetic resin. Each terminal is disposed on the inner bottom portion of the insulating case 31, and one end portion of each terminal is led out from both side surfaces of the insulating case 31.

  The first terminal 32 is formed of a conductive metal material, and has an attachment hole 32a to which the fixed contact 33 is fixed on one end side. The first terminal 32 is insulated on the other end side. A connection terminal portion 32 b led out from the side surface portion of the case 31 is provided. Further, the first terminal 32 is provided with an inclined portion 32 d, and this inclined portion 32 d is embedded and attached to the inner bottom portion of the insulating case 31.

  The second terminal 34 is formed of a conductive metal material, and a projecting portion 34a to which one end portion of the bimetal piece is welded is formed on one end side. Further, a connection terminal portion 34 b led out from the side surface portion of the insulating case 31 is provided on the other end side of the second terminal 34. Further, the second terminal 34 is provided with an inclined portion 34 d, and this inclined portion 34 d is embedded and attached to the inner bottom portion of the insulating case 31.

  The bimetal piece 35 is formed by, for example, laminating and joining two types of metal materials having different thermal expansion coefficients, a high expansion material made of a material having high electrical resistance and a low expansion material made of a material having low electrical resistance, in a flat plate shape. Is formed. A movable contact 36 that contacts and separates from the fixed contact 33 is fixed to one end side of the bimetal piece 35, and the other end side is welded to a protruding portion 34 a provided in the second terminal 34. It has become. Further, a bulged dome-shaped reversing portion 35 a for promoting a reversing action is formed at the center of the bimetal piece 35.

  The cover 37 is formed in a substantially plate shape from an insulating material such as a synthetic resin, is attached on the opening of the insulating case 31, and is provided with first and second terminals 32 disposed in the insulating case 31. 34, the bimetal piece 35, the movable contact 36, the fixed contact 33, and the like are prevented from being affected by dust, gas, and the like.

  Next, the operation will be described. At a normal temperature and a normal use temperature, the movable contact 36 and the fixed contact 33 arranged to face each other come into contact with each other and are in an on state. When the temperature rises for some reason from this state, the bimetal piece 35 performs an inversion operation in response to the temperature rise. At this time, the movable contact 36 fixed to the bimetal piece 35 is separated from the fixed contact 33 and the contact is turned off.

  Furthermore, when the temperature drops from this state and returns to the original room temperature, the bimetal piece 35 reverses and recovers as the temperature drops, the movable contact 36 contacts the fixed contact 33, and the contact is turned on. It will return to the state.

JP 2001-52580 A

  In recent years, there has been a demand for resin molding (hot melt) in a mold of a circuit board on which electronic components are mounted in order to improve the strength of an electric device against a drop impact. However, in the above-described conventional thermally responsive switch, since the cover is formed of a thin resin plate, there is a problem that the cover may be deformed by pressure during resin molding.

  Accordingly, an object of the present invention is to solve the above-described problems, to prevent a cover from being deformed, and to provide a thermally responsive switch capable of resin molding.

  In order to solve the above-mentioned problems, in the present invention, as a first solving means, a case made of a synthetic resin having a storage part whose upper surface is opened, and a first and a part of the case that are partly exposed in the storage part are arranged. A second fixed terminal and a movable contact that is housed in the housing portion, one end side of which is connected to the first fixed terminal, and a fixed contact provided on the second fixed terminal are fixed to the other end side. A reversible bimetal piece and a synthetic resin cover that is polymerized on the case so as to cover the storage portion, and the resin when the case and the cover are resin-molded on the cover It was set as the structure which formed the metal deformation | transformation prevention part which can endure a fluid pressure.

As a second solution, the deformation preventing portion is formed of a metal core material, and the core material is formed by being embedded in the cover.
Further, as a third solving means, the core material is formed of a metal plate material, a part thereof is exposed on the lower surface side of the cover to form an exposed portion, and when the bimetal piece is reversed, the movable contact It was set as the structure which formed so that the edge part to which this was fixed and the said exposed part could contact | abut.
As a fourth solution, the peripheral portion of the housing portion of the case and the overlapping portion of the cover are fixed to each other by ultrasonic welding over the entire circumference.

  As described above, the thermally responsive switch according to the present invention has a case made of a synthetic resin having a storage portion whose upper surface is opened, and the first and second fixed parts that are partly exposed in the storage portion. A reversible bimetal piece that is housed in a housing and is housed in a housing portion, one end of which is connected to the first fixed terminal, and a movable contact that contacts and separates from the fixed contact provided on the second fixed terminal on the other end And a cover made of synthetic resin that is polymerized on the case so as to cover the storage portion, and a metal deformation preventing portion that can withstand the resin flow pressure when the case and the cover are resin-molded on the cover Since it is formed, the deformation of the cover made of synthetic resin can be prevented and the movable region of the movable contact portion in the housing portion of the case can be surely secured, so that a thermally responsive switch capable of resin molding can be provided.

In addition, since the deformation prevention portion is formed of a metal core and the core is integrally embedded in the cover, the metal deformation prevention portion can be easily formed on the synthetic resin cover by insert molding. .
Further, the core material is formed of a metal plate material, and a part of the core material is exposed to the lower surface side of the cover to form an exposed portion, and when the bimetal piece is reversed, the end portion and the exposed portion to which the movable contact is fixed Because the bimetal piece is reversed by the heat during resin molding and the movable contact part comes into contact with the cover, the movable contact part can be stuck into the cover or the cover can be scraped off. Can be prevented.
In addition, since the peripheral portion of the housing portion of the case and the overlapped portion of the cover are fixed by ultrasonic welding over the entire circumference, the entire periphery of the overlapped portion of the cover and the case can be adhered by ultrasonic welding. It is possible to improve the airtightness in the storage portion during resin molding.

  Embodiments of the thermally responsive switch of the present invention are shown in FIGS. 1 is a cross-sectional view of a thermally responsive switch of the present invention, FIG. 2 is a plan view showing a state where a cover of the thermally responsive switch is removed, FIG. 3 is a cross-sectional view of the cover of the thermally responsive switch, and FIG. FIG. 5 is an operation explanatory view of the bimetal piece inversion operation.

  In the figure, the case 1 is formed in a box shape whose upper surface is opened with an insulating material made of synthetic resin, and is provided with a storage portion 1a. In the inner bottom portion of the storage portion 1a of the case 1, each fixed terminal to be described later is integrally embedded, and a part of one end side thereof is exposed and disposed. The other end side of each fixed terminal Are led out from the both side surfaces of the case 1 respectively. A circular concave groove 1 b is provided at the center of the inner bottom portion of the case 1. A boss 1c that protrudes upward is provided at one of the two corners of the opening of the case 1, and the boss 1c and an engagement recess 8a of a cover 8 to be described later are locked so that the cover 8 is in the case. 1 is positioned.

  The first fixed terminal 2 is formed in a flat plate shape with a conductive metal material such as brass. One end side of the first fixed terminal 2 is bent toward the bottom surface inside the case 1 and extends to the center of the storage portion 1a of the case 1, and this extended tip Is exposed on the inner bottom surface of the groove 1b, and a contact piece 2a is provided. In addition, on one end side of the storage portion 1a, a protrusion 2b that is biased upward by a press or the like is formed in the vicinity of the base that is connected to the contact piece 2a. The protrusion 2b is a bimetal piece 6 to be described later. It becomes the welding part fixed to the one end part.

  Further, the other end side of the first fixed terminal 2 is bent toward the bottom surface inside the case 1, and the bent tip side is led out from the side surface portion of the case 1 to the other side. There is provided a connection terminal portion 2c connected to the electronic equipment.

  Similarly, the second fixed terminal 3 is formed in a flat plate shape from a conductive metal material such as brass. One end side of the second fixed terminal 3 is exposed to the other end side of the storage portion 1a of the case 1, and a fixed contact 3a that comes into contact with a movable contact 7 described later is provided at the center. .

  Further, the other end side of the second fixed terminal 3 is bent toward the bottom side inside the case 1 as in the case of the first fixed terminal 2, and the bent tip side is the case 1. There is provided a connection terminal portion 3c that is led out from the side surface portion of the device and connected to another electronic device or the like.

  A positive temperature coefficient thermistor 4 is held in the concave groove 1b. The positive temperature coefficient thermistor 4 is an electronic element (PTC element) that generates heat when energized, has a disk shape, and has upper and lower electrodes. The upper and lower electrodes of the positive temperature coefficient thermistor 4 correspond to the concave groove 1b. And sandwiched between a contact piece 2a of the first fixed terminal 2 exposed on the inner bottom surface and a spring portion 5a of a leaf spring piece 5 to be described later fixed to one end of the second fixed terminal 3 And is held in an electrically connected state.

  The positive temperature coefficient thermistor 4 is configured to perform a self-holding operation for generating heat and holding the inverted state of the bimetal piece 6 when a bimetal piece 6 described later is inverted due to a temperature change.

  The leaf spring piece 5 is formed of a conductive metal plate having spring properties, and has a substantially flat spring portion 5a and a pair of attachment portions extending in a U shape from both ends of the spring portion 5a with the opening 5b interposed therebetween. 5c. This leaf spring piece 5 has a spring portion 5a facing the contact piece 2a of the first fixed terminal 2 exposed on the inner bottom surface of the concave groove 1b, and the mounting portion 5c is the second fixed terminal. 3 is fixed to one end side by a method such as resistance welding.

  At this time, the leaf spring piece 5 is attached in a state where the fixed contact 3a provided at the center on the one end side of the second fixed terminal 3 is exposed from the opening 5b of the attachment portion 5c. The movable contact 7 provided on the bimetal piece 6 to be described later is brought into contact with and separated from the fixed contact 3a through the opening 5a.

  The leaf spring piece 5 is disposed on the upper side of the positive temperature coefficient thermistor 4 held in the concave groove 1b provided in the center of the inner bottom of the case 1, and one end of the upper electrode of the positive temperature coefficient thermistor 4 and the spring The other end of the lower electrode of the positive temperature coefficient thermistor 4 is held in pressure contact with the contact piece 2a exposed on the inner bottom surface of the concave groove 1b by the elasticity of the leaf spring piece 5. Yes. Thus, since the positive temperature coefficient thermistor 4 can be elastically held by the spring property of the leaf spring piece 5, it can be securely held while preventing damage, and the electrical connection between the first fixed terminal 2 and the second fixed terminal 3. Connection can be ensured.

  The bimetal piece 6 is formed by, for example, laminating at least two kinds of metal materials having different thermal expansion coefficients in a flat plate shape, a high expansion material made of a material having a high coefficient of thermal expansion and a low expansion material made of a material having a low coefficient of thermal expansion. It is formed by bonding. One end of the bimetal piece 6 is fixed to the protruding portion 2b provided on the first fixed terminal 2 by a method such as laser welding. On the other hand, a movable contact 7 made of silver tin oxide or the like, which is in contact with or separated from the fixed contact 3a, is fixed to the other end which is a free end of the bimetal piece 6 by a method such as laser welding.

In this case, the connection portion between the first fixed terminal 2 and one end of the bimetal piece 6 is a partial connection with the protruding portion 2 b formed by partially protruding from the first fixed terminal 2. Therefore, when the bimetal piece 6 performs a reversing operation, the bimetal piece 6 is easily reversed and does not hinder the operation characteristics.
In addition, a bulged dome-shaped reversing part 6a for promoting a reversing action is formed at the center of the bimetal piece 6, and by forming this reversing part 6a, The reversal operation according to the temperature characteristic, that is, the temperature, can be reliably performed.

  The cover 8 is formed in a box shape whose bottom surface is opened from an insulating material made of synthetic resin. In addition, a concave engagement recess 8a is provided at one of the two corners of the opening of the cover 8, and the engagement recess 8a and the boss 1c of the case 1 are locked to each other so as to cover the case 1 and the cover. 8 is positioned and polymerized. In this case, the peripheral edge portion of the storage portion 1a of the case 1 and the peripheral edge portion of the opening on the lower surface of the cover 8 are in close contact with each other.

  Further, a core material 9 made of a flat metal plate is integrally embedded in the upper plate portion 8b of the cover 8 by a method such as insert molding. The core material 9 is embedded over substantially the entire surface of the upper plate portion 8b of the cover 8 that is flat. Further, an exposed portion 9a is formed on the lower surface side of the upper plate portion 8b of the cover 8 by exposing a part of the flat plate-like core member 9, and the exposed portion 9a and the bimetal are formed. The one end side to which the movable contact 7 of the piece 6 is fixed is disposed so as to be opposed. When the bimetal piece 6 is reversed, the end portion to which the movable contact 7 is fixed and the exposed portion 9a are formed so as to contact each other.

Further, the cover 8 is formed with an inclined portion 8c so that the fixed side of the bimetal piece 6 is thick and the free end side (movable contact 7 side) is thin, and the core 9 can be embedded and held. In addition, the height can be reduced while avoiding interference with the bimetal piece 6. (See Figure 3)
Further, the core material 9 is connected to the hoop material via the connecting portion 9 b and is integrally formed, and can be mass-produced by cutting the connecting portion 9 b in the recess 8 d provided on the side wall of the cover 8. In addition, since the end surface of the cut portion of the connecting portion 9b does not protrude outward from the recess 8d, the outer shape can be reduced and the handling operation can be performed safely. (See Figure 4)

  In order to assemble the thermally responsive switch having the above structure, the positive temperature coefficient thermistor 4 is accommodated in the concave groove 1b of the storage portion 1a of the case 1 in which the first and second fixed terminals 2 and 3 are disposed. In the state where the spring portion 5a of the leaf spring piece 5 is connected to the upper electrode of 4, the attachment portion 5c of the leaf spring piece 5 is fixed to one end side of the second fixed terminal 3 by a method such as resistance welding. The lower spring electrode 5 holds the lower electrode of the positive temperature coefficient thermistor 4 in pressure contact with the contact piece 2 a of the first fixed contact 2. At this time, the leaf spring piece 5 is attached in a state in which the fixed contact 3a provided at the center on the one end side of the second fixed terminal 3 is exposed from the opening 5b of the attachment portion 5c.

  Next, the bimetallic piece 6 is inserted into the housing 1 a of the case 1 with the fixed contact 3 a and the movable contact 7 facing each other, and one end of the bimetallic piece 6 is laser welded to the protruding portion 2 b of the first fixed terminal 2. It adheres by methods such as. At this time, the fixed contact 3a and the movable contact 7 are in an electrically connected state. In this state, a switch block is formed.

  Next, the cover 8 is covered from the upper side of the switch block, and the bosses 1c provided at the two corners of the housing part 1a of the case 1 and the engaging recesses 8a provided at the two corners of the opening of the cover 8 are provided. Lock, position and overlap. Then, the overlapping surfaces of the case 1 and the cover 8 are welded by a method such as ultrasonic welding, and the switch block and the cover 8 are integrated to complete the assembly.

  In this state, the first and second fixed terminals 2 and 3 are electrically connected via the bimetal piece 6, and the positive temperature coefficient thermistor 4 is connected to the first and second fixed terminals 2 and 2. 3 are connected in parallel.

  In this case, the case 1 and the cover 8 are integrally brought into close contact with each other by ultrasonic welding in a state where the spring portion 5a of the leaf spring piece 5 is elastically contacted with the positive temperature coefficient thermistor 4. Since the characteristic thermistor 4 is elastically held by the leaf spring piece 5 and there is no risk of cracking or damage even when vibration is applied during ultrasonic welding, the sealing performance of the case 1 and the cover 8 can be improved. It is possible to prevent liquid and gas from entering. Further, the entire circumference of the overlapping portion of the case 1 and the cover 8 can be brought into close contact by ultrasonic welding, and the hermeticity in the storage portion during resin molding can be improved.

  A circuit in which the core 9 made of a flat metal plate is integrally embedded in the upper plate portion 8b of the cover 8 by a method such as insert molding, and an electronic component such as a thermally responsive switch is mounted. Since the substrate is formed with a deformation prevention portion when the resin mold (hot melt) is performed in the mold, the metal deformation prevention portion can be easily formed on the cover 8 made of synthetic resin by insert molding. It can be formed.

  In addition, this metal deformation | transformation prevention part may cover and form the metal frame so that the cover 8 may be covered from the outer side besides what is integrated with the cover 8 by insert molding. Further, in the case of insert molding, it is possible to use a linear material in addition to the flat metal plate. In any case, it is possible to prevent the cover 8 from being deformed in the inverted region of the bimetal piece 6, that is, in the height direction of the housing portion 1 a of the case 1.

Next, the operation of the thermally responsive switch having the above configuration will be described.
As shown in FIG. 1, at normal temperature and normal use temperature, the movable contact 7 and the fixed contact 3 a arranged to face each other are in contact with each other and the contact is in an on state. At this time, the bimetal piece 6 and the positive temperature coefficient thermistor 4 are connected in parallel between the first and second fixed terminals 2 and 3, but the bimetal height is equal to the internal resistance value of the positive temperature coefficient thermistor 4. Since the resistance value 6 is extremely smaller, no current flows through the positive temperature coefficient thermistor 4, and the current applied between the first and second fixed terminals 2 and 3 flows through the bimetal piece 6. .
Therefore, a substantial current does not flow on the positive characteristic thermistor 4 side, and the positive characteristic thermistor 4 hardly generates heat.

  When the temperature rises for some reason from this state, as shown in FIG. 5, the reversing portion 6a provided on the bimetal piece 6 to which the movable contact 7 is fixed performs a reversing operation in response to the temperature rise. At this time, the movable contact 7 fixed to the bimetal piece 6 is driven together with the bimetal piece 6 to be separated from the fixed contact 3a, and the contact is turned off. In this case, the bulging portion of the inverted portion 6 a of the inverted bimetal piece 6 is inverted and protrudes in the direction of the positive temperature coefficient thermistor 4, that is, in the direction of the inner bottom surface of the case 1.

  At this time, one end side of the bimetallic piece 6 to which the movable contact 7 is fixed is reversed by the reversing portion 6a, so that the core material 9 made of a metal plate is exposed on the lower surface side of the upper plate portion 8b of the cover 8. It will be in the state contact | abutted to the exposed part 9a. Thus, when the bimetal piece 6 is reversed, the end portion to which the movable contact 7 is fixed and the exposed portion 9a are formed so as to be able to come into contact with each other. Even if the end portion to which the movable contact 7 is fixed comes into contact with the upper plate portion 8b of the cover 8, the bimetal piece 6 can be prevented from sinking into the cover 8 or from being scraped off. Further, the bimetal piece 6 is not deformed and the set temperature is not shifted.

When the contact is turned off in this way, the voltage between the first and second fixed terminals 2 and 3 is applied to the positive characteristic thermistor 4, and the positive characteristic thermistor 4 operates, that is, energizes to generate heat. . Due to the heat generated by the positive temperature coefficient thermistor 4, the bimetal piece 6 is held at the reverse position shown in FIG. 5, and the movable contact 7 and the fixed contact 3 a remain off. That is, it becomes a self-holding state.
At this time, the heat generated by the positive temperature coefficient thermistor 4 is efficiently transmitted to the bimetal piece 6 because the dome-shaped inversion portion 6a of the bimetal piece 6 is disposed in close proximity to the positive temperature coefficient thermistor 4. Become.

  In order to release the OFF state of the self-held contact, the applied voltage between the first and second fixed terminals 2 and 3 may be cut off. In this way, when the temperature drops from this state and returns to the normal temperature, the reversing portion 6a of the bimetal piece 6 reverses and recovers in accordance with the temperature fall, and in the direction opposite to the direction of the positive temperature coefficient thermistor 4. Since it protrudes, the movable contact 7 comes into contact with the fixed contact 3, the contact is turned on, and the initial state is restored.

According to the above-described structure of the thermally responsive switch of the present invention, the case 1 made of synthetic resin having the storage portion 1a having the upper surface opened, and the part of the case 1 that is exposed and disposed in the storage portion 1a. The first and second fixed terminals 2 and 3 and the first fixed terminal 2 are connected to the first fixed terminal 2 at one end and the second fixed terminal 3 is fixed at the other end. The reversible bimetal piece 6 to which the movable contact 7 that contacts and separates from the contact 3a is fixed, and the synthetic resin cover 8 that is polymerized on the case 1 so as to cover the storage portion 1a. When the case 1 and the cover 8 are resin-molded, the deformation preventing portion forms the cover by holding the metal core 9 on the upper plate portion 8b of the resin 8. Is it possible for the upper plate part 8b of 8 to withstand the resin flow pressure? By providing the core 9 made of metal, the cover 8 made of synthetic resin can be prevented from being deformed, and the movable region of the movable contact portion in the housing portion 1a of the case 1 can be reliably secured. It is possible to provide a possible heat responsive switch.
In the above embodiment, the self-holding positive temperature coefficient thermistor is described. However, the present invention can also be applied to a thermally responsive switch that does not have a self-holding function.

It is sectional drawing which shows the thermally responsive switch of this invention. It is a top view which shows the state which removed the cover of the thermally responsive switch of this invention. It is sectional drawing which shows the cover of the thermally responsive switch of this invention. It is a bottom view which shows the cover of the thermally responsive switch of this invention. It is operation | movement explanatory drawing which shows the time of the inversion operation | movement of the bimetal piece of this invention. It is a perspective view which shows the conventional heat responsive switch. It is sectional drawing which shows the conventional heat responsive switch.

Explanation of symbols

1: Case 1a: Storage part 1b: Groove 1c: Boss 2: First fixed terminal 2a: Contact piece 2b: Protruding part 2c: Connection terminal part 3: Second fixed terminal 3a: Fixed contact 3c: Connection terminal part 4: Positive temperature coefficient thermistor 5: Leaf spring piece 5a Spring portion 5b: Opening portion 5c: Mounting portion 6: Bimetal piece 6a: Reversing portion 7: Moving contact 8: Cover 8a: Engaging recess 8b: Upper plate portion 8c: Inclined portion 8d: Concave part 9: Core material (deformation preventing part)
9a: exposed part 9b: connecting part

Claims (4)

  A case made of a synthetic resin having a storage portion whose upper surface is opened, first and second fixed terminals partially exposed in the storage portion, and stored in the storage portion, the first A reversible bimetal piece having one end connected to the fixed terminal and a movable contact fixed to and away from the fixed contact provided on the second fixed terminal to the other end, and the reversible bimetal piece so as to cover the storage portion A synthetic resin cover that is polymerized on the case, and the cover is formed with a metal deformation preventing portion that can withstand a resin flow pressure when the case and the cover are resin-molded. Thermally responsive switch.   2. The thermally responsive switch according to claim 1, wherein the deformation preventing portion is formed of a metal core material, and the core material is integrally embedded in the cover.   The core material is formed of a metal plate material, and a part thereof is exposed on the lower surface side of the cover to form an exposed portion. When the bimetal piece is reversed, the end portion to which the movable contact is fixed and the front surface are formed. 3. The heat responsive switch according to claim 2, wherein the heat responsive switch is formed so as to be able to contact the protruding portion. The thermally responsive switch according to any one of claims 1 to 3, wherein the peripheral portion of the housing portion of the case and the overlapping portion of the cover are fixed to each other by ultrasonic welding.

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