JP7622343B2 - Electronics - Google Patents

Description

The present invention relates to electronic equipment that is fixed to an equipment mounting rail.

Electronic devices used in factory automation (FA), such as sensor controllers for FA sensors and programmable logic controllers, are fixed to a metal rail called a DIN rail. Such electronic devices use a metal heat-conducting plate as a heat dissipation member to dissipate heat generated by heat-generating components inside the housing to the equipment mounting rail (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 9-162574

The use of a large amount of metal materials, which are more expensive than resin materials, for heat dissipation makes the electronic device expensive. Therefore, the object of the present invention is to provide an electronic device that can transfer heat from heat-generating components to the device mounting rails rather than to other adjacent electronic devices , and that is also highly cost-competitive.

An electronic device according to one aspect of the present disclosure is fixed to an equipment mounting rail. The electronic device includes a circuit board on which a heat-generating component is mounted, and a resin housing that houses the circuit board. The resin housing is composed of a first member that is integrally molded with a bottom wall portion provided with a locking claw that can be engaged with the equipment mounting rail, and a column portion that stands from the bottom wall portion and to which the circuit board is fixed, and a second member that is fixed to the bottom wall portion and houses the circuit board in a closed space partitioned between the first member and the bottom wall portion. The first member is formed of a resin material that has a higher thermal conductivity than the second member.

According to this aspect, the first member has a column portion for fixing the circuit board on which the heat generating component is mounted, and is integrally molded with the bottom wall portion that engages with the equipment mounting rail. The first member, which has a higher thermal conductivity than the second member, is used as a heat dissipation member, and the heat of the heat generating component can be efficiently dissipated to the equipment mounting rail. A plurality of electronic devices (control devices) are often arranged and fixed on the equipment mounting rail. Since the second member has a lower thermal conductivity than the first member, the heat of the heat generating component is preferentially transmitted to the equipment mounting rail rather than to other adjacent electronic devices. The heat is unlikely to adversely affect other electronic devices. Since a heat dissipation member made of resin material, which is cheaper than metal material, is used, the manufacturing cost can be reduced. Since injection molding of resin material is easier to process into complex shapes than press processing of metal material, the number of parts of the heat dissipation sheet that fills the gap between the heat generating component and the heat dissipation member can be reduced, and the manufacturing cost can be reduced. Since the resin housing can be sealed using ultrasonic welding or the like, which was not possible when joining metal material and resin material, the manufacturing efficiency is excellent.

In the above aspect, the column portion is formed in a flat plate shape having a first main surface and a second main surface opposite the first main surface, and the mounting surface of the circuit board on which the heat-generating component is mounted may be arranged to face either the first main surface or the second main surface.

According to this aspect, the pillars constituting the heat dissipation member can ensure a large heat dissipation area for the circuit board, so heat can be efficiently dissipated through the pillars to the equipment mounting rail.

In the above aspect, at least one of the first main surface and the second main surface may have an area larger than the mounting surface.

In this embodiment, the areas of the first and second main surfaces that face the mounting surface are large, making it easier for the column portion to provide a large heat dissipation area for the circuit board.

In the above aspect, the device may further include a connector that can be connected to an external device, and the column portion may have a through hole that penetrates the first main surface and the second main surface, and the connector may be inserted into the through hole.

According to this aspect, even if the closed space inside the plastic housing is divided by the pillars and narrowed, a connector larger than the dimensions after division can be placed inside the plastic housing.

In the above embodiment, the resin housing may have a sealed structure.

A sealed housing is characterized by the fact that dust is less likely to get inside, but heat tends to build up inside. When the housing is made only of resin material, which is less able to dissipate heat than metal materials, it is difficult to choose a sealed structure. According to this embodiment, even a plastic housing can dissipate heat more efficiently than conventional products, so that a sealed structure can be selected even for a plastic housing. Because both the first and second members are made of a plastic material, the plastic housing can be sealed using ultrasonic welding or the like. This has excellent cost and manufacturability.

In the above embodiment, the electronic device may be an amplifier unit of a separate amplifier type sensor.

The amplifier unit of a sensor with a separate amplifier is connected to the sensor it senses by wire, so it cannot be installed too far away from the object to be detected. A sealed structure is preferable to prevent contamination by the object to be detected. With this configuration, a sealed structure can be selected even with a plastic housing, making it ideal for the amplifier unit of a sensor with a separate amplifier.

In the above aspect, the electronic device may be a fiber sensor including a main unit in which a light-emitting element, a light-receiving element, and a detection circuit are housed in a resin housing, a sensor head for irradiating light on an object and receiving the light, a fiber for connecting the main unit and the sensor head, and a fiber connection section for connecting the fiber to the light-emitting element and the light-receiving element.

Fiber sensors cannot be installed too far from the object to be detected because the length of the fiber is limited. A sealed structure is preferable to prevent contamination by the object to be detected. This configuration allows a sealed structure to be selected even for a plastic housing, making it ideal for fiber sensors.

In the above embodiment, the first member and the second member may be formed from the same base resin material.

According to this aspect, by aligning the base material of the resin material forming the first member and the base material of the resin material forming the second member, the melting points of the base materials become the same and chemical affinity is improved, so that when the first member and the second member are fixed by means of welding, adhesion, or the like, the joining surfaces can be firmly fixed.

In the above embodiment, the second member may be formed from a polybutylene terephthalate resin containing an inorganic filler, and the first member may be formed from a polybutylene terephthalate resin containing a different type of inorganic filler from that of the second member.

According to this aspect, the first member can be formed from a resin material that has a large difference in thermal conductivity from the second member. Because the base material of the first member and the second member is the same, when the first member and the second member are fixed together by welding or bonding, the joining surfaces can be firmly fixed.

In the above embodiment, the thermal conductivity of the first member may be at least twice the thermal conductivity of the second member. The thermal conductivity of the first member may be at least 0.9 W/m·K.

According to this aspect, the first member, which has a sufficiently high thermal conductivity, can be used as a heat dissipation member to efficiently dissipate heat from the heat-generating component to the equipment mounting rail.

The present invention makes it possible to provide electronic devices that have excellent heat dissipation properties and are also cost-competitive.

FIG. 1 is a partially see-through perspective view of an electronic device according to an embodiment of the present invention. FIG. 2 is a side view of the electronic device shown in FIG. 1 as viewed from the extending direction of the device mounting rail. FIG. 3 is a bottom view of the locking claw shown in FIG. 2 as viewed from the bottom side of the equipment mounting rail. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a perspective view showing the first member with the second member and the like removed from the electronic device shown in FIG. FIG. 6 is a perspective view showing the internal structure of the electronic device in the vicinity of the connector shown in FIG.

A preferred embodiment of the present invention will be described with reference to the attached drawings. In each drawing, the same reference numerals are used to denote the same or similar configurations. Each configuration will be described in detail below with reference to the drawings. FIG. 1 is a partially see-through perspective view of an electronic device according to an embodiment of the present invention. As shown in FIG. 1, the electronic device 1 is used while being fixed to an equipment mounting rail 9. The equipment mounting rail 9 is, for example, a DIN rail, and has standardized dimensions and shapes as stipulated in JIS C2812:1998, which is the JIS (Japanese Industrial Standard) that corresponds to DIN (German Industrial Standard).

In the illustrated example, the electronic device 1 is configured as an amplifier unit of a separate amplifier type sensor, and includes a connector 5 (first connector 51) to which a sensor unit equipped with a sensing function can be connected. The amplifier unit further includes a cable 6 that can be connected to an external power source that supplies power, a connector 5 (second connector 52) that can be connected to an external device, etc., and amplifies the signal detected by the sensor unit and converted into an electrical signal, and transmits it to the external device.

However, the electronic device 1 is not limited to the amplifier unit of a separate amplifier type sensor. The electronic device 1 may be a fiber sensor including a main unit in which a light-emitting element that emits light, a light-receiving element that receives light, and a detection circuit that detects changes in both the light reaching the light-receiving element and converts them into an electrical signal are housed in a resin housing 2, a sensor head for irradiating an object with light and receiving the light, a fiber for connecting the main unit and the sensor head, and a fiber connection section for connecting the fiber to the light-emitting element and the light-receiving element. It may also be another type of FA sensor. When the electronic device 1 is a fiber sensor, the first connector 51 is configured as a connector for connecting to a fiber.

The connector 5 and cable 6 mentioned above are connected to the circuit board 3 (first and second boards 31, 32). The circuit board 3 is equipped with an amplifier section that amplifies the signal detected by the sensor unit and converted into an electrical signal, a signal processing section that processes the signal output from the amplifier section, a communication section that transmits the output of the signal processing section to an external device, and a control section that controls the amplifier section and communication section. These are composed of heat-generating components 33 such as IC chips.

The circuit board 3 is housed in a plastic housing 2. The plastic housing 2 can be divided in the vertical direction indicated by the Z axis in FIG. 1, and is composed of a first member 10 that can be fixed to an equipment mounting rail 9, and a second member 20 that is fixed to the first member 10. The plastic housing 2 includes a substantially box-shaped bottom wall portion 11, peripheral wall portion 21, and top wall portion 22 that define a sealed closed space. The first member 10 constitutes the bottom wall portion 11, and the second member 20 constitutes the peripheral wall portion 21 and top wall portion 22.

The first member 10 has a column portion 12 standing up from the bottom wall portion 11 in addition to the bottom wall portion 11 described above. The column portion 12 is disposed within the closed space of the plastic housing 2. The circuit board 3 is fixed to the column portion 12. The second member 20 has a peripheral wall portion 21 and a top wall portion 22 described above, and further has a panel recess 23 provided outside the closed space of the plastic housing 2. The operation panel 4 is placed in the panel recess 23. The operation panel 4 includes an indicator that allows the user to visually check the operating status of the amplifier unit, operation buttons that allow the user to input operations, and a circuit board that controls them.

Figure 2 is a side view of the electronic device 1 shown in Figure 1 along the X-axis, which is the extension direction of the equipment mounting rail. Figure 3 is a bottom view of the locking claw 13 shown in Figure 2, viewed from the bottom side of the equipment mounting rail 9. As shown in Figure 2, the second connector 52 is sealed by an attached cover except when in use. As shown in Figures 2 and 3, the first member 10 has a locking claw 13 that can engage with the equipment mounting rail 9. By hooking the locking claw (first locking claw) 13 onto the equipment mounting rail 9 and attaching the external locking claw (second locking claw) 19 to the first member 10, the electronic device 1 can be fixed to the equipment mounting rail 9.

Figure 4 is a cross-sectional view taken along line IV-IV in Figure 2. As shown in Figure 4, Figure 5 is a perspective view showing only the first member 10 with the second member 20 and circuit board 3 removed from the electronic device 1 shown in Figure 1. As shown in Figure 5, the column portion 12 is formed in a flat plate shape having a first main surface (left side surface) 12A, a second main surface (right side surface) 12B opposite the first main surface 12A, and an end surface connecting the first and second main surfaces 12A and 12B.

The first and second main surfaces 12A, 12B extend along the YZ plane perpendicular to the X-axis, which is the extension direction of the equipment mounting rail 9. Note that the first main surface 12A and the second main surface 12B of the column portion 12 have substantially the same shape and function, so the first main surface 12A will be described in detail as a representative, and a duplicate description of the second main surface 12B will be omitted.

As shown in FIG. 5, the column portion 12 has multiple bosses 14 for self-tapping screws provided on the first and second main surfaces 12A, 12B, and protrusions 15 provided on the first and second main surfaces 12A, 12B and having the same protruding height as the bosses 14. The column portion 12 has a through hole 12H that penetrates the first and second main surfaces 12A, 12B.

Figure 6 is a perspective view showing the internal structure of the electronic device in the vicinity of the second connector 52 shown in Figure 1. As shown in Figure 6, the second connector 52 is formed in a rectangular column shape extending from one end 52A to the other end 52B opposite to the one end 52A along the X-axis, which is the extension direction of the equipment mounting rail 9, and the second connector 52 is inserted into a through hole 12H formed in the column portion 12. In other words, the one end 52A protrudes from the first main surface 12A of the column portion 12, and the other end 52B protrudes from the second main surface 12B. The shape of the second connector 52 is not limited to the example shown in the figure, and may be cylindrical or another shape.

One end 52A and the other end 52B are provided with contact terminals that mechanically engage and electrically connect with contact terminals of a connector of an external device. Openings are formed in the peripheral wall portion 21 of the resin housing 2 at positions corresponding to the one end 52A and the other end 52B. As described above, the openings in the peripheral wall portion 21 are sealed by the attached cover except when in use. In the illustrated example, the second connector 52 is fixed directly to the first circuit board 31 and penetrates the mounting surface of the first circuit board. An opening is formed in the second circuit board 32 at a position corresponding to the other end 52B of the second connector 52.

As shown in FIG. 4, the circuit board 3 is arranged so that the mounting surface on which the heat-generating components 33 are mounted faces the first main surface 12A, and is fixed to the boss 14 of the column portion 12 by the tightening screw 15. The mounting surface may be arranged so that it faces the second main surface 12B, and the circuit board 3 may be fixed to the column portion 12. In the illustrated example, the circuit board 3 is divided into a first circuit board 31 and a second circuit board 32, which are fixed to the first and second main surfaces 12A and 12B of the column portion 12, respectively. As shown in FIG. 1, the first main surface 12A is formed so as to have a larger area than the mounting surface of the first circuit board 31. Similarly, although not shown, the second main surface 12B is formed so as to have a larger area than the mounting surface of the second circuit board 32.

As shown in FIG. 4, a heat dissipation sheet 34 is disposed in the gap between the heat generating component 33 and the column 12. The adhesive heat dissipation sheet 34 adheres to the column 12 and heat generating component 33 so as to fill the gap, improving the thermal conductivity from the heat generating component 33 to the column 12. The gap between the heat generating component 33 and the column 12 may be filled with a thermally conductive paste or the like instead of the heat dissipation sheet 34.

The interior of the resin housing 2 is partitioned as a sealed closed space. Since both the first and second members 10, 20 are made of resin material, the first and second members 20 can be joined using ultrasonic welding or the like. As shown in FIG. 4, the end face 21E of the peripheral wall 21 of the second member 20 is tightly attached to the inner surface 11A of the bottom wall portion 11 of the first member 10 without any gaps.

As shown in FIG. 5, the bottom wall 11 provided with the locking claws 13 that can engage with the equipment mounting rail 9 and the column 12 to which the circuit board 3 is fixed are integrally molded. In the conventional product, for example, the metal column extends through the resin bottom wall to the equipment mounting rail 9, and the gap between the heat-generating component 33 and the side of the column and the gap between the bottom end of the column and the equipment mounting rail 9 are filled with a heat dissipation sheet 34. Since a column with a complex shape cannot be formed by pressing metal materials, it was necessary to use more heat dissipation sheet 34 than in this embodiment. In contrast, according to this embodiment, the column 12 and the bottom wall 11 are integrally molded by injection molding of a resin material, so the heat dissipation sheet 34 that was necessary in the gap between the metal column and the equipment mounting rail 9 can be omitted. The gap between the heat-generating component 33 and the column 12 is also small. The amount of heat dissipation sheet 34 used can be reduced.

One of the features of the electronic device 1 of this embodiment is that the first member 10 is made of a resin material with a higher thermal conductivity than the second member 20. The second member 20 is made of, for example, polybutylene terephthalate resin containing an inorganic filler such as glass fiber. The first member 10 may be made of polybutylene terephthalate resin containing a different type of inorganic filler from that of the second member 20. The inorganic filler with high thermal conductivity may be an inorganic filler of metal oxide or a metal filler.

Alternatively, the filler of the first and second members 10 and 20 may be the same type. In that case, the first member 10 may have a higher filler content than the second member 20. The base material of the resin material of the first and second members 10 and 20 is not limited to polybutylene terephthalate resin. It may be polycarbonate resin, polyamide resin, or polyphenylene sulfide resin. Various base materials can be selected as long as they are resin materials with excellent moldability, electrical properties, heat resistance, mechanical properties, etc. If the base material of the resin material forming the first member 10 and the base material of the resin material forming the second member 20 are the same, the melting points of the base materials will be the same and the chemical affinity will be improved, so that when the first member 10 and the second member 20 are fixed by means of welding, adhesion, etc., the joining surface 21E (shown in FIG. 4) can be firmly fixed.

The thermal conductivity of the first member is desirably at least twice the thermal conductivity of the second member. The thermal conductivity of the second member 20 is, for example, about 0.33 W/m·K. The thermal conductivity of the first member 10 is, for example, 0.5 to 10 W/m·K, and preferably 0.9 W/m·K or more. The thermal conductivity of the first member and the second member can be measured, for example, by a measurement method specified in ISO 22007-2:2015 or the like.

According to the electronic device 1 of the present embodiment configured as described above, the column portion 12 for fixing the circuit board 3 on which the heat-generating component 33 is mounted and the bottom wall portion 11 for engaging with the equipment mounting rail 9 are integrally molded using a resin material with high thermal conductivity, so that the heat from the heat-generating component 33 can be efficiently dissipated to the equipment mounting rail 9. The manufacturing cost of the electronic device 1 can be reduced because a heat dissipation member made of a resin material such as polybutylene terephthalate resin, which is less expensive than metal materials, is used. Since both the first and second members 10 and 20 are made of a resin material, the resin housing 2 can be sealed using ultrasonic welding or the like, which could not be selected when joining metal and resin materials. Since a sealed structure that is less likely to dissipate heat can be selected even for the resin housing 2, it is particularly suitable for amplifier units of amplifier-separated sensors and fiber sensors.

The above-described embodiments are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. The elements of the embodiments, as well as their arrangements, materials, conditions, shapes, sizes, etc., are not limited to those exemplified, and may be modified as appropriate. Furthermore, configurations shown in different embodiments may be partially substituted or combined.

[Additional Notes]
An electronic device (1) fixed to an equipment mounting rail (9),
A circuit board (3) on which a heat generating component (33) is mounted;
A resin housing (2) that houses the circuit board (3),
The resin housing (2) is
a first member (10) in which a bottom wall portion (11) is provided with a locking claw (13) engageable with the equipment mounting rail (9) and a pillar portion (12) standing from the bottom wall portion (11) and to which the circuit board (3) is fixed is integrally formed;
a second member (20) that is fixed to the bottom wall portion (11) and that accommodates the circuit board (3) in a closed space defined between the second member (20) and the bottom wall portion (11);
The first member (10) is formed of a resin material having a higher thermal conductivity than the second member (20).
Electronic devices.

1...electronic device, 2...plastic housing, 3...circuit board, 4...operation panel, 5...connector, 6...cable, 9...equipment mounting rail, 10...first member, 11...bottom wall, 11A...inner surface, 12...column, 12A...first main surface, 12B...second main surface, 12H...through hole, 13...locking claw, 14...boss, 15...projection, second locking claw...19, 20...second member, 21...peripheral wall, 21E...end surface, 22...top wall, 23...panel recess, 31...first board, 32...second board, 33...heat generating component, 34...heat dissipation sheet, 35...tightening screw, 51...first connector, 52...second connector, 52A...one end, 52B...other end.

Claims (10)

An electronic device fixed to an equipment mounting rail,
A circuit board on which a heat generating component is mounted;
a resin housing that houses the circuit board;
The resin housing is
a first member having a bottom wall portion provided with a locking claw capable of engaging with the equipment mounting rail and a column portion standing from the bottom wall portion and to which the circuit board is fixed, the first member being integrally formed;
a second member fixed to the bottom wall portion and configured to accommodate the circuit board in a closed space defined between the second member and the bottom wall portion,
The first member and the second member are formed from the same base resin material, and joint surfaces of the first member and the second member are welded together, and the first member is formed from a resin material having a higher thermal conductivity than the second member.
Electronic devices. The column portion is formed in a flat plate shape having a first main surface and a second main surface opposite to the first main surface,
a mounting surface of the circuit board on which the heat generating component is mounted is disposed so as to face either one of the first main surface or the second main surface;
2. The electronic device according to claim 1. At least one of the first main surface and the second main surface has an area larger than that of the mounting surface.
3. The electronic device according to claim 2. Further comprising a connector that can be connected to an external device,
A through hole is formed in the column portion, the through hole penetrating the first main surface and the second main surface, and the connector is inserted into the through hole.
4. The electronic device according to claim 2 or 3. The resin housing has a sealed structure.
The electronic device according to claim 1 . The electronic device is an amplifier unit of an amplifier-separated sensor,
The electronic device according to claim 1 . The electronic device is a fiber sensor including a main unit in which a light-emitting element, a light-receiving element, and a detection circuit are housed in the resin housing, a sensor head for irradiating light to an object and receiving the light, a fiber for connecting the main unit and the sensor head, and a fiber connection portion for connecting the fiber to the light-emitting element and the light-receiving element.
The electronic device according to claim 1 . the second member is formed of a polybutylene terephthalate resin containing an inorganic filler,
The first member is formed of a polybutylene terephthalate resin containing a different type of inorganic filler from that of the second member.
The electronic device according to claim 1 . The thermal conductivity of the first member is at least twice the thermal conductivity of the second member.
The electronic device according to claim 1 . The thermal conductivity of the first member is 0.9 W/m·K or more.
The electronic device according to claim 1 .