Patent Description:
In the electronic device disclosed in <CIT> ("the '<NUM> Publication"), a plurality of bosses project from a back surface of a refrigerator, which is a heating element. A circuit portion including a circuit board is fixed to the distal end surfaces of the plurality of bosses. A protective casing is attached to the back surface of the refrigerator so as to cover the circuit portion.

As in the '<NUM> Publication, bosses projecting from a heating element conduct heat from the heating element directly to a circuit portion. This may cause the circuit portion to overheat due to a high temperature of the heating element. Further, <CIT> discloses a detector module, a cooling arrangement as well as a lithographic apparatus comprising a detector module.

The present invention addresses such a drawback, and one object thereof is to prevent overheating of the circuit portion due to the heat from the heating element.

With the present invention, the heat from the heating element is conducted to the casing and passes through the side wall and the bottom wall of the casing to reach the boss and further the circuit portion. When the heat passes such a path, the heat is radiated from the casing while it is conducted through the casing. Accordingly, the amount of the heat reaching the circuit portion can be reduced to prevent overheating of the circuit portion.

One embodiment of an aircraft actuator having an electronic device applied thereto will be hereinafter described with reference to the drawings.

As shown in <FIG>, an aircraft actuator <NUM> includes a cylinder <NUM> having a cylindrical shape. The interior of the cylinder <NUM> constitutes a fluid chamber for containing a hydraulic fluid which is fed into and discharged out of the fluid chamber. In the fluid chamber, a rod <NUM> having a columnar shape is positioned coaxially with the cylinder <NUM>. The rod <NUM> reciprocates in the axial direction of the cylinder <NUM> in accordance with the hydraulic pressure of the hydraulic fluid. Apart of the distal end side of the rod <NUM> projects from one end of the cylinder <NUM>. The distal end portion of the rod <NUM> forms a mounting portion 14A to which an operating object to be operated by the aircraft actuator <NUM> is mounted. The mounting portion 14A has an annular shape. The operating object is a flap of an aircraft. Although not shown, the other end portion of the cylinder <NUM> forms a mounting portion for engaging with a mounting object to which the aircraft actuator <NUM> is mounted. The mounting object is a main wing of the aircraft.

A manifold <NUM> is fixed to the outer surface of the cylinder <NUM>. The manifold <NUM> contains a hydraulic circuit defined therein. The hydraulic circuit includes a solenoid valve or the like for switching the flow path in the hydraulic circuit. The hydraulic fluid for the hydraulic circuit is fed into and discharged out of the cylinder <NUM>. The manifold <NUM> is a heating element that emits heat to an outside in accordance with the power applied to the solenoid valve and the temperature of the hydraulic fluid. The manifold <NUM> heats in accordance with the power applied to the solenoid valve and the temperature of the hydraulic fluid, and the outer surface of the manifold <NUM> may heat to <NUM> or higher. When the high temperature heat of the manifold <NUM> reaches a circuit portion <NUM> of an electronic device <NUM>, the circuit portion <NUM> may overheat, and thus it needs to release the heat.

The electronic device <NUM> is attached to the outer surface of the manifold <NUM>. A casing <NUM> of the electronic device <NUM> is a housing having an opening, and specifically, it is shaped like a quadrangular bottomed box. More specifically, the casing <NUM> has a bottom wall <NUM> shaped like a rectangular flat plate in plan view. As shown in <FIG>, a side wall <NUM> rises from an edge 62A of the bottom wall <NUM>, or an end surface thereof. The side wall <NUM> rises in the direction away from the bottom wall <NUM>. <FIG> shows the rising direction of the side wall <NUM> downward from the bottom wall <NUM>. The side wall <NUM> extends over the whole stretch of the edge 62A of the bottom wall <NUM>. The side wall <NUM> rises the same length over its whole stretch along the edge 62A of the bottom wall <NUM>. The side wall <NUM> also has the same thickness <NUM> over its whole stretch along the edge 62A of the bottom wall <NUM>. The thickness <NUM> of the side wall <NUM> is smaller than the thickness <NUM> of the bottom wall <NUM>. The distal end of the side wall <NUM> in its rising direction as a whole forms an edge of a quadrangular opening <NUM>. In other words, the opening <NUM> of the casing <NUM> is provided on the opposite side to the bottom wall <NUM> with respect to the side wall <NUM>. Further, a flange <NUM> projects outward from the distal end of the side wall <NUM> in its rising direction. The flange <NUM> extends over the whole stretch of the side wall <NUM>. In other words, the flange <NUM> is shaped like a quadrangular frame in plan view from the opening <NUM> of the casing <NUM>. The casing <NUM> is made of an aluminum alloy.

The walls of the casing <NUM> are penetrated by a plurality of through-holes <NUM> in the thickness direction of the walls. Specifically, among the walls of the casing <NUM>, the side wall <NUM> has a plurality of through-holes <NUM> that communicate between the inside and the outside of the casing <NUM>. As shown in <FIG>, the plurality of through-holes <NUM> are arranged at intervals along the edge of the bottom wall <NUM>. The plurality of through-holes <NUM> are disposed as follows. Each of the faces of the side wall <NUM> rising from the long sides of the edge 62A of the bottom wall <NUM> has two through-holes <NUM>, and each of the faces of the side wall <NUM> rising from the short sides has one through-hole <NUM>. The bottom wall <NUM> of the casing <NUM> also has a plurality of through-holes <NUM> that communicate between the inside and the outside of the casing <NUM>. The plurality of through-holes <NUM> are positioned in the vicinity of the edge 62A of the bottom wall <NUM>. The plurality of through-holes <NUM> are arranged at intervals along the edge 62A of the bottom wall <NUM>. The plurality of through-holes <NUM> are disposed as follows. Each of the regions along the long sides of the edge 62A of the bottom wall <NUM> has two through-holes <NUM>, and each of the regions along the short sides has one through-hole <NUM>.

A plurality of fins <NUM> project from the outer surface of the bottom wall <NUM> toward the opposite side to the opening <NUM> of the casing <NUM>. Each of the fins <NUM> has a columnar shape and rises from the bottom wall <NUM>.

As shown in <FIG>, a plurality of bosses <NUM> project from the inner surface of the bottom wall <NUM> toward the opening <NUM> of the casing <NUM>. In other words, the bosses <NUM> project toward the side to which the side wall <NUM> rises from the bottom wall <NUM>, or toward the opposite side to the bottom wall <NUM> with respect to the side wall <NUM>. Each of the bosses <NUM> is shaped like a pillar and rises perpendicularly from the bottom wall <NUM>. All the bosses <NUM> have the same projection length <NUM>. The projection length <NUM> of each of the bosses <NUM> is smaller than a half of the rise length of the side wall <NUM>. Although not shown, each of the bosses <NUM> has a bolt hole formed in the distal end surface thereof toward the bottom wall <NUM>.

Each of the bosses <NUM> is spaced apart from the edge 62A of the bottom wall <NUM> and positioned closer to the middle of the bottom wall <NUM> than are the through-holes <NUM>. The shortest distance <NUM> between each of the bosses <NUM> and the edge 62A of the bottom wall <NUM> is larger than the projection length <NUM> of the bosses <NUM>.

The casing <NUM> contains a circuit portion <NUM> including a plate-shaped circuit board. <FIG> does not show components mounted on the circuit board in the circuit portion <NUM>. The circuit portion <NUM> has a rectangular shape one size smaller than that of the bottom wall <NUM> of the casing <NUM> in plan view from the opening <NUM> of the casing <NUM>. The circuit portion <NUM> is retained to the distal end surfaces of the bosses <NUM> and fixed to the bosses <NUM> with bolts 70B each corresponding to one of the bosses <NUM>. Each of the bolts 70B, corresponding to one of the bosses <NUM>, penetrates the circuit portion <NUM> and is screwed into the bolt hole of the boss <NUM>.

The casing <NUM> also contains a heat insulator <NUM> made of a heat-insulating material. The heat insulator <NUM> is positioned on the opening <NUM> side of the circuit portion <NUM>. The heat insulator <NUM> has a rectangular parallelepiped shape. In plan view from the opening <NUM> of the casing <NUM>, the outer dimensions of the heat insulator <NUM> are the same as those of the bottom wall <NUM>. The heat insulator <NUM> is fixed to the inner surface of the side wall <NUM> with an adhesive, for example. The heat insulator <NUM> is made of polyurethane.

A base <NUM> shaped like a rectangular plate is attached to the flange <NUM> of the casing <NUM>. The outer dimensions of the base <NUM> are the same as the rectangular outer dimensions formed by the outer edge of the flange <NUM>. In plan view from the opening <NUM> of the casing <NUM>, the base <NUM> is positioned such that the four sides of the base <NUM> are aligned with the four sides of the flange <NUM>. The base <NUM> and the flange <NUM> are fixed to each other with a bolt B provided for each side of the flange <NUM> shaped like a quadrangular frame. Since the base <NUM> is attached to the flange <NUM>, the opening <NUM> of the casing <NUM> faces the base <NUM>. The base <NUM> is made of a stainless steel. The base <NUM> is thus made of a material having a lower thermal conductivity than the casing <NUM>.

Four spacers <NUM> are attached to the surface of the base <NUM> opposite to the casing <NUM>. The spacers <NUM> are positioned at the four corners of the base <NUM>. Each of the spacers <NUM> has a cylindrical shape. Each of the spacers <NUM> contacts with the base <NUM> at one end surface thereof. The spacers <NUM> are fixed to the base <NUM> with an adhesive, for example. The spacers <NUM> are made of a stainless steel. The spacers <NUM> are thus made of a material having a lower thermal conductivity than the casing <NUM>.

Each of the spacers <NUM> contacts with the outer surface of the manifold <NUM> at the end surface thereof opposite to the base <NUM>. Each of the spacers <NUM> is fixed to the manifold <NUM> with a bolt C provided therefor. Specifically, the bolts C are inserted through the four corners of the flange <NUM> of the casing <NUM>, the four corners of the base <NUM>, and the spacers <NUM>. The bolts C are screwed into the manifold <NUM>. In this way, the base <NUM> and the casing <NUM> are attached to the manifold <NUM> via the spacers <NUM>. As described above, since the opening <NUM> of the casing <NUM> faces the base <NUM>, the casing <NUM> is attached to the manifold <NUM> at the opening <NUM> side thereof via the base <NUM> and the spacers <NUM>. In other words, the side wall <NUM> of the casing <NUM> is attached to the manifold <NUM> at the opposite side to the bottom wall <NUM>. Since the projection length <NUM> of the bosses <NUM> is smaller than a half of the rise length of the side wall <NUM> of the casing <NUM>, the distance Z between the outer surface of the manifold <NUM> and the distal end surfaces of the bosses <NUM> is larger than the projection length <NUM> of the bosses <NUM>.

Operation of the embodiment will be now described. The heat in the outer surface of the manifold <NUM> reaches the electronic device <NUM> attached to the outer surface of the manifold <NUM>. The heat in the manifold <NUM> follows the following path to reach the circuit portion <NUM> in the electronic device <NUM>. The heat in the manifold <NUM> is conducted through the spacers <NUM> and the base <NUM> to the casing <NUM>. The heat conducted to the casing <NUM> is conducted through the side wall <NUM> to the bottom wall <NUM> of the casing <NUM>. In this way, the heat in the manifold <NUM> follows a properly long path to reach the circuit portion <NUM>. Accordingly, the heat is radiated from the walls while it is conducted through the walls. After the heat is conducted to the bottom wall <NUM>, it passes through the bosses <NUM> and reaches the circuit portion <NUM>. The amount of the heat reaching the circuit portion <NUM> is properly small. Therefore, the amount of the heat conducted to the circuit portion <NUM> can be reduced.

Advantageous effects of the embodiment will be now described.

The foregoing embodiment can be modified as described below. The above embodiment and the following modifications can be implemented in combination to the extent where they are technically consistent with each other.

The shape of the casing <NUM> is not limited to that in the above embodiment. The casing <NUM> may be any housing including the bottom wall <NUM> and the side wall <NUM> rising from the bottom wall <NUM>. The casing <NUM> is not limited to the quadrangular box-like shape but may have a circular box-like shape, or in other words, a cylindrical shape with one end thereof closed, or a polygonal box-like shape other than a quadrangle. The bottom wall <NUM> is not limited to the plate-like shape but may be curved. The side wall <NUM> may rise obliquely so as to diverge toward the opening <NUM>.

The material of the casing <NUM> is not limited to that in the above embodiment. For example, the casing <NUM> may be made of a stainless steel. When the casing <NUM> is made of a material having a properly low thermal conductivity, less heat is conducted through the side wall <NUM> and the bottom wall <NUM> of the casing <NUM>, and thus the amount of heat conducted from the manifold <NUM> and reaching the circuit portion <NUM> can be reduced.

The positions of the bosses <NUM> are not limited to those in the above embodiment. The bosses <NUM> can be at any positions at which to project from the bottom wall <NUM>. The bosses <NUM> may be positioned at the edge 62A of the bottom wall <NUM> in the casing <NUM>. In this case, the heat from the manifold <NUM> still passes through the side wall <NUM> and reaches the bosses <NUM>. The heat is radiated while it is conducted through the side wall <NUM>, and thus the amount of heat reaching the circuit portion <NUM> can be reduced.

The projection length <NUM> of the bosses <NUM> are not limited to that in the above embodiment. When it is not intended to reduce the amount of the radiation heat conducted from the manifold <NUM> to the circuit portion <NUM>, the projection length <NUM> of the bosses <NUM> may be larger than the distance Z between the outer surface of the manifold <NUM> and the distal end surfaces of the bosses <NUM>. In this case, the bosses <NUM> may have any projection length <NUM> that is smaller than the rise length of the side wall <NUM>. With this arrangement, the circuit portion <NUM> fixed to the bosses <NUM> are not positioned outside the casing <NUM>.

A single boss <NUM> may be provided instead of the plurality of bosses <NUM>.

The number and positions of the through-holes <NUM> in the casing <NUM> are not limited to those in the above embodiment. The through-holes <NUM> may be provided closer to the middle of the bottom wall <NUM>.

The though-holes <NUM> may be omitted. In this case, the amount of the heat reaching the circuit portion <NUM> still can be reduced through the heat radiation from the outer surface of the casing <NUM>.

The thickness <NUM> of the side wall <NUM> in the casing <NUM> is not limited to that in the above embodiment. The thickness <NUM> of the side wall <NUM> may be the same as or larger than the thickness <NUM> of the bottom wall <NUM>. In these cases, the amount of the heat reaching the circuit portion <NUM> still can be reduced through the heat radiation from the outer surface of the side wall <NUM>.

The number and the positions of the spacers <NUM> are not limited to those in the above embodiment. The spacers <NUM> may be positioned closer to the middle of the base <NUM>.

The shape of the spacers <NUM> is not limited to that in the above embodiment. For example, the spacers <NUM> may have a polygonal tubular shape. The spacers <NUM> may have any shape that can be attached to the base <NUM> and the manifold <NUM>.

The material of the spacers <NUM> is not limited to that in the above embodiment. The spacers <NUM> may be made of an aluminum alloy. The spacers <NUM> may be made of a material other than those having a lower thermal conductivity than the casing <NUM>. Irrespective of the material of the spacers <NUM>, the presence of the spacers <NUM> maintains a proper distance between the base <NUM> and the outer surface of the manifold <NUM>, and thus the radiation heat conducted from the manifold <NUM> and reaching the base <NUM> can be reduced. In addition, the heat from the manifold <NUM> is radiated from the spacers <NUM> while it is conducted through the spacers <NUM>, and thus the amount of the heat reaching the circuit portion <NUM> can be reduced. The plurality of spacers <NUM> may be made of different materials.

The spacers <NUM> may be omitted. The base <NUM> may thus be attached directly to the outer surface of the manifold <NUM>. In this case, for example, the bolts are inserted through the flange <NUM> of the casing <NUM> and the base <NUM> and screwed into the manifold <NUM>. With the base <NUM> attached directly to the outer surface of the manifold <NUM>, the opening <NUM> of the casing <NUM> is also attached to the manifold <NUM> via the base <NUM> provided between the casing <NUM> and the manifold <NUM>. In this arrangement, the heat from the manifold <NUM> still passes through the base <NUM> and the side wall <NUM> and the bottom wall <NUM> of the casing <NUM> and reaches the bosses <NUM>. The heat is radiated while it is conducted through these walls, and thus the amount of heat reaching the circuit portion <NUM> can be reduced.

The material of the base <NUM> is not limited to that in the above embodiment. When it is not intended to inhibit the heat conduction from the manifold <NUM> to the casing <NUM>, the material of the base <NUM> may be changed desirably. The base <NUM> may be made of an aluminum alloy. The base <NUM> may be made of a material having a higher thermal conductivity than the material of the casing <NUM>. Irrespective of the material of the base <NUM>, the presence of the base <NUM> prevents the radiation heat from the manifold <NUM> from being conducted directly to the interior of the casing <NUM>. In addition, the heat from the manifold <NUM> is radiated from the base <NUM> while it is conducted through the base <NUM>, and thus the amount of the heat reaching the circuit portion <NUM> can be reduced.

The shape of the base <NUM> is not limited to that in the above embodiment. The base <NUM> may have any shape that can close the opening <NUM> of the casing <NUM>. The base <NUM> may have a polygonal plate-like shape other than a quadrangle or may have any shape other than the plate-like shape such as a rectangular parallelepiped.

When it is not necessary to prevent the radiation heat from the manifold <NUM> from being conducted directly to the interior of the casing <NUM>, the base <NUM> may be omitted. The casing <NUM> may thus be attached directly to the outer surface of the manifold <NUM>. In this case, for example, the bolts are inserted through the flange <NUM> of the casing <NUM> and screwed into the manifold <NUM>. With the casing <NUM> attached directly to the outer surface of the manifold <NUM>, the opening <NUM> of the casing <NUM> is attached directly to the manifold <NUM>. In the arrangement without the base <NUM>, the heat from the manifold <NUM> still passes through the side wall <NUM> and the bottom wall <NUM> of the casing <NUM> and reaches the bosses <NUM>. The heat is radiated while it is conducted through these walls, and thus the amount of heat reaching the circuit portion <NUM> can be reduced.

The fins <NUM> may be omitted. Even without the fins <NUM>, the heat is radiated from the outer surface of the bottom wall <NUM>. When the fins <NUM> are omitted, for example, the outer surface of the bottom wall <NUM> may have a wavy shape with an increased surface area. The increased surface area increases the efficiency of the heat radiation from the bottom wall <NUM>.

The material of the heat insulator <NUM> is not limited to that in the above embodiment.

The heat insulator <NUM> may be omitted.

The electronic device <NUM> may be attached to heating elements other than the manifold <NUM>. The electronic device <NUM> may be attached to any heating elements in the aircraft actuator <NUM> other than the manifold <NUM>, or it may be attached to heating elements in any constituents other than the aircraft actuator <NUM>. The electronic device <NUM> may be attached to any heating elements installed on an aircraft.

The electronic device <NUM> may be attached to an aircraft actuator different from that in the above embodiment. For example, some aircraft actuators convert a rotational motion of a motor into a linear motion and transmit the linear motion to a rod. In such aircraft actuators, a housing containing the motor heats in accordance with the power applied to the motor. The electronic device <NUM> may be attached to such a housing.

Claim 1:
An electronic device (<NUM>) for an aircraft, comprising:
a casing (<NUM>) including a bottom wall (<NUM>) and a side wall (<NUM>) rising from the bottom wall (<NUM>), wherein a heating element (<NUM>) is attached to the side wall (<NUM>) at an opposite side to the bottom wall (<NUM>);
a boss (<NUM>) projecting from the bottom wall (<NUM>) toward the opposite side to the bottom wall (<NUM>) with respect to the side wall (<NUM>); and
a circuit portion (<NUM>) fixed to the boss (<NUM>), characterized in that the electronic device (<NUM>) for an aircraft further comprising a base (<NUM>) provided between the casing (<NUM>) and the heating element (<NUM>),
wherein the base (<NUM>) is made of a material having a lower thermal conductivity than the casing (<NUM>),
wherein a spacer (<NUM>) is attached to the base (<NUM>),
wherein the base (<NUM>) is attached to the heating element (<NUM>) via the spacer (<NUM>),
wherein the spacer (<NUM>) is made of a material having a lower thermal conductivity than the casing (<NUM>),
wherein the circuit portion (<NUM>) is fixed to a distal end surface of the boss (<NUM>), and
wherein a distance (Z) between the heating element (<NUM>) and the distal end surface of the boss (<NUM>) is larger than a projection length (<NUM>) of the boss (<NUM>) from the bottom wall (<NUM>).