JP6289354B2 - Condensation prevention structure for electric circuit boards - Google Patents

Description

  The present invention relates to a dew condensation prevention structure that does not cause dew condensation on an electric circuit board housed in an exterior member of an actuator that drives a valve.

  An exhaust gas recirculation (EGR) valve is mounted in the engine of the vehicle. Heat generated by the engine is transmitted to the actuator via the valve housing. Further, the heat of the exhaust gas flowing through the passage in the valve housing is transmitted to the actuator through a bearing member or the like. For this reason, the actuator that drives the EGR valve tends to become high temperature due to heat from the outside in addition to self-heating of the actuator itself. On the other hand, the temperature of the external atmosphere of the EGR valve is determined by the outside air temperature, the heat generated by the engine, and the traveling wind of the vehicle, and generally the actuator tends to be higher in temperature than the external atmosphere. Therefore, the actuator is cooled by the temperature difference between the external atmosphere and the actuator, and condensation occurs on the outer wall of the actuator. As this dew condensation progresses, dew condensation water adheres to the electric circuit board housed in the vicinity of the exterior, causing a problem in the electrical conductivity of the electric circuit board.

  As a structure for preventing the occurrence of dew condensation, for example, there is a simple double sash described in Patent Document 1. This is a structure in which a hollow frame member is attached to each of the four sides of the window sash to form a frame, and the opening surface of the frame is closed with a transparent plate. When this occurs, there is a problem that condensed water flows out from the gap.

JP 2009-35862 A

  In the actuator, there is a problem that poor conduction occurs when condensed water adheres to the electric circuit board. Therefore, it is necessary to prevent condensation from forming on the outer wall of the exterior of the actuator and to prevent the condensed water from adhering to the electric circuit board.

  The present invention has been made to solve the above-described problems, and an object thereof is to protect an electric circuit board of an actuator from dew condensation.

The dew condensation prevention structure for an electric circuit board according to the present invention comprises: a dew condensation prevention cover for covering at least a portion housing the electric circuit board from the outside of the exterior member of the actuator; and a sealing member for closing a gap between, on the exterior member of the actuator, is shall be formed vents for communicating the enclosed space surrounded by the dew condensation preventing cover the internal space of the package member.

  According to this invention, since a sealed space is formed between the exterior member of the actuator and the dew condensation prevention cover and the external atmosphere temperature is difficult to be transmitted to the exterior member, it is possible to prevent dew condensation from occurring on the inner wall of the exterior member, The electric circuit board can be protected from condensation.

It is a figure which shows the structural example of the EGR valve to which the dew condensation prevention structure which concerns on Embodiment 1 of this invention is applied. 3 is a cross-sectional view illustrating a configuration example of a main part of the dew condensation prevention structure according to Embodiment 1. FIG. 4 is an external perspective view showing a configuration example of a dew condensation prevention cover of the dew condensation prevention structure according to Embodiment 1. FIG. It is a fragmentary sectional view of the dew condensation prevention cover shown in FIG. It is a side view which shows the actuator before attaching the dew condensation prevention cover shown in FIG. 6 is an external perspective view showing a modification of the dew condensation prevention cover of the dew condensation prevention structure according to Embodiment 1. FIG. It is a fragmentary sectional view of the dew condensation prevention cover shown in FIG.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration example of an EGR valve 1 to which a dew condensation prevention structure according to Embodiment 1 of the present invention is applied, and shows a configuration on the valve housing 2 side of the EGR valve 1 in a sectional view. . The valve housing 2 is formed with an exhaust gas passage 2a through which exhaust gas flows. Further, a filter 3, a bearing portion 4, a seal (not shown), and the like are installed in a hole penetrating the valve housing 2. The bearing portion 4 supports the rod 5 so as to be slidable in the axial direction. A valve 6 is fixed to the lower end of the rod 5. A valve seat 7 is installed in the middle of the exhaust gas passage 2a, and the valve 6 contacts and separates from the valve seat 7 to open and close the exhaust gas passage 2a. FIG. 1 shows a closed state in which the valve 6 and the valve seat 7 are in contact with each other.

  An actuator 10 that operates the rod 5 in a direction in which the valve 6 moves away from the valve seat 7 (a valve opening direction) is fixed to the upper opening end of the valve housing 2. The actuator shaft 11 of the actuator 10 operates in the axial direction to push the rod 5 in the valve opening direction. On the other hand, a spring 8 that operates the rod 5 in a direction in which the valve 6 is in contact with the valve seat 7 (valve closing direction) is installed in the internal space 2 b between the actuator 10 and the bearing portion 4. Furthermore, a holder 9 attached to the rod 5 is disposed in the internal space 2 b, and the urging force of the spring 8 is transmitted to the rod 5 through the holder 9.

  The actuator 10 is composed of a DC motor or the like, and drives the actuator shaft 11 in the vertical direction. When the actuator shaft 11 moves downward, the rod 5 is pushed downward and the valve 6 opens. When the actuator shaft 11 moves upward, the urging force of the spring 8 acts to move the rod 5 upward, and the valve 6 is closed. Therefore, the amount of exhaust gas circulated can be adjusted by the actuator 10 controlling the vertical position of the actuator shaft 11.

  The actuator 10 is covered with an exterior member 12. A connector portion 12 a is formed on the upper end portion of the exterior member 12. The upper end portion of the exterior member 12 is covered with a dew condensation prevention cover 20.

FIG. 2 is a cross-sectional view illustrating a configuration example of a main part of the dew condensation prevention structure according to the first embodiment. 3 is an external perspective view of the dew condensation prevention cover 20, and FIG. 4 is a partial sectional view. Further, FIG. 5 shows a side view of the actuator 10 before the dew condensation prevention cover 20 is attached.
In the internal space 12d surrounded by the exterior member 12, members (not shown) such as a rotor, a stator, and a coil that generate a driving force for driving the actuator shaft 11, and an electric for controlling the vertical position of the actuator shaft 11 are controlled. A circuit board 13 and the like are accommodated.

  The condensation prevention structure includes a condensation prevention cover 20 that covers at least a portion of the exterior member 12 of the actuator 10 that houses the electric circuit board 13, and an O that closes a gap between the exterior member 12 and the condensation prevention cover 20. Rings 21 and 22 are included. The O-ring 21 surrounds the body portion of the actuator 10. The O-ring 22 surrounds the connector part 12a.

  The dew condensation prevention cover 20 is formed with an opening 20a for passing the body portion of the actuator 10 and an opening 20b for passing the connector portion 12a. By forming the openings 20a and 20b, a gap is formed between the exterior member 12 and the gap is closed by O-rings 21 and 22. Therefore, the inside of the dew condensation prevention cover 20 is a sealed space 23 that is shielded from the external atmosphere.

  As described above, the external ambient temperature tends to be lower than the temperature of the actuator 10. Therefore, a portion of the exterior member 12 that is not covered with the dew condensation prevention cover 20 is cooled by being exposed to the external atmosphere, and dew condensation occurs on the inner wall. On the other hand, at least a portion of the exterior member 12 that accommodates the electric circuit board 13 is in contact with the sealed space 23 formed by the dew condensation prevention cover 20, so that the external ambient temperature is not easily transmitted. This makes it difficult for condensation to occur on the inner wall 12 c in the vicinity of the electric circuit board 13, and prevents the condensed water from adhering to the electric circuit board 13. Further, the EGR valve 1 is not increased in size by covering only the portion to be protected from condensation with the condensation prevention cover 20.

  Since the condensation prevention cover 20 is in contact with the external atmosphere, there is a possibility that condensation will occur in the sealed space 23, but the condensed water generated on the inner wall of the condensation prevention cover 20 stays in the sealed space 23, so It does not adhere to the circuit board 13.

  However, when the external ambient temperature environment is severe, such as when the external ambient temperature is extremely low, condensed water is generated on the inner wall 12c due to the temperature difference between the sealed space 23 where the temperature has decreased and the internal space 12d of the exterior member 12. Therefore, when the EGR valve 1 is used in such a harsh environment, the air hole 12b may be added. For example, as shown in FIG. 2, a ventilation hole 12b is formed in a portion of the exterior member 12 that is covered with the dew condensation prevention cover 20, and a space between the sealed space 23 and the internal space 12d of the exterior member 12 is formed through the ventilation hole 12b. To eliminate the temperature difference. Thereby, it is prevented that dew condensation water is generated on the inner wall 12c.

Further, the condensed water staying in the sealed space 23 can be discharged to the outside through the vent hole 12b.
In the configuration example of FIGS. 1 and 2, the sealed space 23 and the internal space 12d of the exterior member 12 are directly connected through the vent hole 12b. In addition, since there is a gap for moving the actuator shaft 11 up and down between the exterior member 12 and the actuator shaft 11, the internal space 12d of the exterior member 12 and the internal space 2b of the valve housing 2 are passed through this gap. Connected directly. Further, the internal space 2 b of the valve housing 2 and the outside are directly connected through a through hole 2 c formed in the valve housing 2. By forming the ventilation hole 12b, the outside of the actuator 10 and the sealed space 23 surrounded by the dew condensation prevention cover 20 communicate with each other. Therefore, the dew condensation water staying in the sealed space 23 flows to the internal space 12d of the exterior member 12 through the vent hole 12b, flows to the internal space 2b of the valve housing 2 through the gap between the exterior member 12 and the actuator shaft 11, It is discharged to the outside through the through hole 2c.

  The drainage path of the condensed water is not limited to the above configuration. For example, a through hole is formed in a portion of the exterior member 12 that faces the internal space 2b of the valve housing 2, and condensed water flows from the internal space 12d of the exterior member 12 to the internal space 2b of the valve housing 2 through the through hole. May be.

  The vent hole 12 b is preferably not formed in the vicinity of the electric circuit board 13, but is formed at a position farthest from the electric circuit board 13 in the exterior member 12 covered with the dew condensation prevention cover 20. Thereby, even when the vent hole 12b is provided, it becomes possible to suppress the adhesion of condensed water to the electric circuit board 13 as much as possible.

  As described above, according to the first embodiment, the dew condensation prevention structure includes the dew condensation prevention cover 20 that covers at least the portion of the exterior member 12 of the actuator 10 that houses the electric circuit board 13 from the outside, and the actuator 10. O-rings 21 and 22 that close the gap between the exterior member 12 and the dew condensation prevention cover 20 are provided. Since the sealed space 23 is formed between the exterior member 12 and the dew condensation prevention cover 20 and the external atmosphere temperature is hardly transmitted to the exterior member 12, it is possible to prevent dew condensation from occurring on the inner wall 12c of the exterior member 12. Therefore, the electric circuit board 13 can be protected from dew condensation.

Further, according to the first embodiment, the exterior member 12 of the actuator 10 may be formed with the vent hole 12b that communicates the internal space 12d of the exterior member 12 and the sealed space 23 surrounded by the dew condensation prevention cover 20. . Since the temperature difference between the internal space 12d and the sealed space 23 can be eliminated through the vent hole 12b, it is possible to prevent dew condensation on the inner wall 12c of the exterior member 12. As described above, the vent hole 12b is not an essential configuration, and it is an added value when it is added when the external ambient temperature environment is severe.
Further, the outside of the actuator 10 and the sealed space 23 can be communicated with each other through the vent hole 12b, and the condensed water generated in the dew condensation prevention cover 20 can be discharged to the outside through the vent hole 12b. In the case of this configuration, the dew condensation water staying in the sealed space 23 can be discharged to the outside without being attached to the electric circuit board 13.

Note that the dew condensation prevention structure is not limited to the above configuration. A modification is shown below.
6 is an external perspective view showing a modified example of the dew condensation prevention structure, and FIG. 7 is a partial sectional view.
In the dew condensation prevention structure shown in FIGS. 1 to 5, two O-rings 21 and 22 are used as seal members that close the gap between the exterior member 12 and the dew condensation prevention cover 20. On the other hand, in the dew condensation prevention structure shown in FIGS. 6 and 7, one O-ring 24 is used as a seal member. The O-ring 24 surrounds the body portion of the actuator 10 avoiding the connector portion 12a.

  The condensation prevention cover 20-1 is formed with an opening 20a for allowing the actuator 10 body to pass therethrough and a notch 20c for avoiding the connector portion 12a. By forming the notch 20 c and the opening 20 b, a gap is formed between the exterior member 12 and this gap is closed by the O-ring 24. Therefore, the inside of the dew condensation prevention cover 20-1 is a sealed space 23 that is blocked from the external atmosphere.

  Moreover, in the dew condensation prevention structure shown in FIGS. 1-7, it was set as the structure which uses O-rings 21, 22, and 24 as a sealing member which plugs up the clearance gap between the exterior member 12 and the dew condensation prevention covers 20 and 20-1. However, the present invention is not limited to this, and sealing can be performed by various methods such as an adhesive and welding.

  Moreover, although the example which applied the dew condensation prevention structure to the EGR valve | bulb 1 was shown in FIGS. 1-7, you may apply to the valve | bulb used for uses other than EGR.

  In addition to the above, within the scope of the present invention, any component of the embodiment can be modified or any component of the embodiment can be omitted.

  1 EGR valve (exhaust gas recirculation valve), 2 valve housing, 2a exhaust gas passage, 2b internal space, 2c through hole, 3 filter, 4 bearing part, 5 rod, 6 valve, 7 valve seat, 8 spring, 9 holder DESCRIPTION OF SYMBOLS 10 Actuator, 11 Actuator shaft, 12 Exterior member, 12a Connector part, 12b Vent hole, 12c Inner wall, 12d Internal space, 13 Electric circuit board, 20, 20-1 Condensation prevention cover, 20a, 20b Opening part, 20c Notch 21, 22, 24 O-ring (seal member), 23 sealed space.

Claims (2)

An electrical circuit board condensation prevention structure that does not cause condensation on an electrical circuit board housed in an exterior member of an actuator that drives a valve,
A dew condensation prevention cover for covering at least a portion accommodating the electric circuit board from the outside of the exterior member of the actuator;
A seal member that closes a gap between the actuator exterior member and the condensation prevention cover ;
Wherein the outer member of the actuator, condensation prevention structure for an electric circuit board which is characterized that you have vent holes are formed for communicating the internal space with the enclosed space in which the surrounded by dew condensation preventing cover of the outer member. The valve, dew condensation preventing structure for an electric circuit board according to claim 1 Symbol mounting, characterized in that an exhaust gas recirculation valve that is mounted on a vehicle.

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