JP6778141B2 - Actuator seal structure - Google Patents

Description

The present invention relates to, for example, a seal structure of an actuator attached to an engine and advancing and retreating a driving shaft by expansion and contraction of wax due to a temperature change on the engine side.

There is known a thermoactuator in which the drive shaft moves forward and backward when the wax contained in the element case expands and contracts due to a temperature change. Further, conventionally, it has been proposed to use this thermoactuator as a drive source for a shutter (shielding plate) for a radiator of an engine.

For example, Patent Document 1 discloses a thermoactuator proposed by the applicant. The thermoactuator is shown in FIG. 6, and a conventional thermoactuator and an example of its use will be described with reference to FIG.
As shown in FIG. 6, the thermoactuator 1 supports the element case 3 in which the wax 2 is stored and the element case 3 on the rear end side, and the retainer 4 on the front end side so as to be able to move forward and backward. And. The element case 3 and the support portion 5 are connected by caulking to form a thermo element 6, and the temperature change in the thermo element 6 is converted into a lift amount (movement amount of the retainer 4).
The element case 3 and the support portion 5 constituting the thermo element 6 are made of, for example, brass.

The retainer 4 surrounds a substantially cylindrical guide portion 7 integrally formed with the support portion 5, and a cylindrical piston 8 is provided in the guide portion 7 in the front-rear direction (axial direction). It is held movable to.
Then, the diaphragm 9 is deformed as the wax 2 expands and contracts due to a temperature change. Further, the piston 8 moves back and forth with respect to the guide portion 7 in response to the deformation of the diaphragm 9, so that the retainer 4 is advanced and retreated.

A shaft 12 that protrudes from the tip end side of the retainer 4 coaxially with the retainer 4 is provided, and the shaft 12 is connected to an opening / closing mechanism 20 having a plurality of shielding plates 21 at the tip thereof. As a result, the shaft 12 moves forward and backward in the axial direction in synchronization with the advance / backward movement of the retainer 4, and operates so as to rotate (open / close) the plurality of shielding plates 21 in conjunction with each other.

A tubular casing 10 is provided around the retainer 4 and the support portion 5 so as to surround them, and a return spring 11 that can expand and contract in the axial direction is provided in the gap space between the retainer 4 and the casing 10. Have been placed.
The front end portion of the return spring 11 is seated on the inner front end portion of the casing 10, and the rear end portion is in contact with the flange portion 4a protruding in the circumferential direction at the base end portion of the retainer 4, whereby the return spring 11 is abutted. , The retainer 4 and the shaft 12 are urged in the backward direction.

That is, the retainer 4 is always urged in the backward direction by the return spring 11, but acts on the thermoelement 6 so as to contract the return spring 11 when the retainer 4 advances. A ring-shaped packing 13 is provided in the opening 10e on the front end side of the casing 10, and the inside of the casing 10 is sealed by the packing 13 regardless of the advancing / retreating operation of the retainer 4.

Further, the casing 10 has a casing main body 10a that covers the periphery of the retainer 4 and the thermoelement 6 as described above, and a flange 10b that extends outward from the base end portion of the casing main body 10a. The flange 10b is provided with a through hole 10c used for screwing.
Further, the support portion 5 is press-fitted and connected to the casing main body 10a from the opening 10d on the base end side thereof, and is connected to the flange 10b over the entire circumference from the peripheral surface of the support portion 5 in the outer peripheral direction. The one side (front side) of the flange portion 5a that protrudes is in contact with each other.

To attach the thermoactuator 1 to the engine, first, the element case 3 and the rear portion of the support portion 5 that supports the element case 3 are inserted into a storage hole (not shown) formed in the engine. Further, in a state where the flange portion 5a of the support portion 5 is pressed against the engine side by the flange 10b of the casing 10, the casing 10 is fixed to the engine by using a screw (not shown) inserted through the through hole 10c.
By attaching the thermoactuator 1 to the engine in this way, the shaft 12 can be moved forward and backward by the expansion and contraction of the wax 2 due to the temperature change on the engine side, thereby opening and closing the shielding plate 21 for ventilation control. It can be realized.

By the way, in the thermoactuator 1 shown in FIG. 6 disclosed in Patent Document 1, a packing 13 is attached along the opening 10e on the front end side of the casing 10, and the retainer moves in the axial direction by the packing 13. It is configured to form a seal with No. 4 and prevent, for example, dust or rainwater from outside the casing from entering the thermoactuator 1.

FIG. 7 is a perspective view showing a specific configuration of the thermoactuator 1 in the vicinity of the opening 10e on the front end side of the casing 10 provided with the packing 13 by breaking a part thereof, and is shown in FIG. The parts corresponding to each part are indicated by the same reference numerals.
In the example shown in FIG. 7, the retainer 4 shown in FIG. 6 is integrally molded with the shaft 12 attached to the tip thereof, and the portion corresponding to the retainer 4 shown in FIG. 6 is the shaft 12. It constitutes a large diameter portion 12a. A hollow portion 12b is formed in the large diameter portion 12a along the shaft core, the guide portion 7 is housed in the hollow portion 12b, and the tip portion of the piston 8 protruding from the guide portion 7 is the hollow portion 12b. It is fitted and attached to the shaft 12 inside.

As shown in FIG. 7, in order to apply the ring-shaped packing 13 along the opening (opening for shaft insertion) 10e at the front end of the casing 10, for example, as shown in FIG. 8, the first mold A And injection molding using the second mold (core member) B is used.
That is, the casing main body 10a is mounted between the first mold A and the second mold B, and the space between the first mold A and the second mold B formed along the opening 10e on the front end side thereof. As shown by the white arrows, a rubber material that functions as packing 13 is injected into the portion and injection molded.
Subsequently, heat is applied to the rubber material (indicated by the same reference numeral 13 as the packing) containing the first mold A and the second mold B to cause a chemical reaction (vulcanization), whereby the casing main body 10a The packing 13 can be formed along the opening 10e.

When the packing 13 is formed on the casing body 10a using the first and second molds A and B as described above, the thickness of the casing body 10a is not uniform or the casing body 10a is partially deformed. There is a problem that the molding of the packing 13 is likely to vary due to the influence of the above. Moreover, injection molding by using a mold cannot increase the productivity and has a problem that the production cost also increases.

Therefore, it is conceivable to adopt a configuration in which a single ring-shaped packing is molded in a separate process and the packing is held by a ring-shaped packing holder. For this purpose, a packing having a U-shaped cross section can be preferably used.
FIG. 9 shows an enlarged cross-sectional view of the packing 32 having a U-shaped cross section as a reference example. Also in the example shown in FIG. 9, a configuration in which the packing 32 is arranged along the large diameter portion 12a of the shaft is shown as in the example shown in FIG.

In addition, a ring-shaped packing holder 31 that receives the expanding pressure of the return spring 11 is provided, and a U-shaped cross section is provided in an annular space formed between the packing holder 31 and the large diameter portion 12a of the shaft. The ring-shaped packing 32 made is arranged.
A configuration for sealing between the casing 10 and the large diameter portion 12a of the shaft by using the packing 32 having a U-shaped cross section in this way is disclosed in, for example, Patent Document 2.

Japanese Unexamined Patent Publication No. 2015-105645 JP-A-2010-249144

By the way, according to the configuration of the reference example shown in FIG. 9, one leg of the packing 32 having a U-shaped cross section slides in contact with the large diameter portion 12a of the shaft that moves relative to the axial direction. , This makes it possible to secure a seal for the shaft.
However, in the configuration shown in FIG. 9, since the seal between the outer surface of the packing holder 31 and the inner surface of the casing body 10a is incomplete, for example, an O-ring indicated by reference numeral 33 is attached between the two. Other measures such as are required. Therefore, even in the configuration shown in FIG. 9, since the packing 32 and the O-ring 33 having a U-shaped cross section are provided, the number of parts and the assembly man-hours are inevitably increased, and the cost is the same as in the example shown in FIG. The problem of up cannot be solved.

Therefore, the problem to be solved by the present invention is that good sealing performance can be ensured at two locations between the shaft and the casing by using a single packing, and productivity including assembly man-hours and the like can be ensured. It is an object of the present invention to provide an actuator seal structure which is excellent in quality and can achieve a sufficient reduction in product cost.

The seal structure of the actuator according to the present invention, which has been made to solve the above-mentioned problems, includes a shaft that moves in the axial direction of the actuator, a casing that covers the shaft along the axial direction, and the shaft and the casing. A packing arranged in a space between the two and arranged around an opening for shaft insertion formed at the front end of the casing, the packing is supported on the front side, and the shaft is urged in the backward direction on the back side. A packing holder that receives the contact of the return spring is provided, and the packing has a sliding contact surface that slides into the shaft on the inner peripheral side and one of the inner surfaces of the front end portion of the casing on the outer peripheral side of the sliding contact surface. The contact portion that comes into contact with the portion is integrally formed, and the contact portion of the packing is brought into contact with the inner surface of the front end portion of the casing by receiving the forward action of the packing holder by the return spring . The packing has a cross-sectional shape orthogonal to the circumferential direction formed in a U shape on the inner peripheral side, and the U-shaped inner leg portion is a sliding contact surface that is in sliding contact with the shaft, and is a sliding contact surface on the outer side of the U shape. A disk-shaped contact portion with the casing is continuously formed on the leg portion, and a protrusion protruding in the actuator axial direction is integrally formed with the packing on at least one of the front surface or the back surface of the contact portion. It is characterized by being.

That is, according to the seal structure of the actuator described above, the packing arranged around the shaft insertion opening formed at the front end of the casing has a sliding contact surface that is in sliding contact with the shaft that moves in the axial direction, and this sliding contact. An abutting portion that comes into contact with a part of the inner surface of the front end portion of the casing is integrally formed on the outside of the surface. Then, the contact portion formed on the packing is configured to abut on the inner surface of the front end portion of the casing by receiving the forward action of the packing holder by the return spring.

Further, on the back surface of the packing, a recess is formed along the circumference in the connecting portion between the U-shaped outer leg portion and the contact portion with the casing, and the packing holder is formed on the packing. It is desirable that the protruding portion that fits into the recess is formed on the front side.

Further, as the material of the shaft, it is desirable to use a material having a hardness higher than that of the packing holder.

According to the seal structure of the actuator according to the present invention described above, good sealing performance can be ensured at two locations between the shaft and the casing that move in the axial direction of the actuator by the single packing.
Therefore, it is possible to provide an actuator seal structure that is excellent in productivity including assembly man-hours and can achieve a sufficient reduction in product cost.

It is a perspective view which showed the actuator which adopted the seal structure which concerns on this invention by breaking a part thereof. It is a perspective view which showed the appearance structure of a packing and a packing holder. It is an enlarged cross-sectional view of the state in which the packing is cut at the plane orthogonal to the circumferential direction. It is an enlarged cross-sectional view of the state which cut the packing holder in the plane orthogonal to the circumferential direction. It is an enlarged sectional view in the vicinity of the front end portion of the casing in the actuator shown in FIG. It is sectional drawing which showed the example of the conventional (patent document 1) thermoactuator. It is a perspective view which showed by breaking a part of the conventional example in which packing was injection-molded in the opening of a casing. FIG. 5 is a cross-sectional view illustrating a state in which packing is injection-molded into the opening of the casing shown in FIG. 7, including a mold. It is an enlarged sectional view in the vicinity of the front end portion of the casing of the seal structure which is a reference example.

Hereinafter, the seal structure of the actuator of the embodiment according to the present invention will be described by taking as an example the thermoactuators shown in FIGS. 1 to 5 using a thermoelement that operates depending on the coolant temperature of the engine.
In FIGS. 1 to 5 used in the following description, the same parts are indicated by the same reference numerals, but due to space limitations, some drawings are given reference numerals to the representative parts, and the detailed configuration thereof is described. In some cases, the reference numerals given to other drawings are used for explanation.

In the form of the thermoactuator 1 shown in FIG. 1, a portion corresponding to the retainer 4 shown in FIG. 6 is integrally formed with the shaft 12 to form a large diameter portion 12a of the shaft. That is, the same configuration as the example shown in FIG. 7 is adopted. A hollow portion 12b is formed in the shaft core portion of the large diameter portion 12a, the guide portion 7 is housed in the hollow portion 12b, and the tip portion of the piston 8 protruding from the guide portion 7 is inside the hollow portion 12b. It is fitted to the shaft 12 and attached coaxially.

Further, a flange portion 12c is formed at the base end portion of the large diameter portion 12a, and the rear end portion of the return spring 11 abuts on the collar portion 12c to urge the shaft 12 in the backward direction. Further, the front end portion of the return spring 11 gives a urging force to push the packing 16 toward the front end portion side of the casing 10 via the packing holder 17.

Then, as shown in FIG. 1, an O-ring 15 is attached around the thermo element 6 including the element case 3, and the coolant leaks from the engine (not shown) side to which the thermo actuator 1 is attached. It is configured to prevent it.
The other basic configurations of the thermoactuator 1 shown in FIG. 1 are the same as those shown in FIG. 6, and therefore, the corresponding parts are designated by the same reference numerals as those in FIG. 6, and the overlapping description of each part is omitted. ..

As shown in FIG. 2, the packing 16 is formed in a ring shape by a rubber material, and the packing holder 17 also formed in a ring shape supporting the packing 16 is overlapped with the back side of the packing 16. Be placed.
As shown in FIG. 1, the packing 16 and the packing holder 17 are arranged in a space between the large diameter portion 12a of the shaft 12 and the casing 10. The packing 16 is arranged directly below the shaft insertion opening 10e formed at the front end of the casing 10.

Further, as shown in the enlarged cross-sectional view of FIG. 3, the ring-shaped packing 16 has a U-shaped cross-sectional shape orthogonal to the circumferential direction on the inner peripheral side, and the U-shaped inner leg portion 16a is formed. It constitutes a sliding contact surface that is in sliding contact with the shaft. That is, as shown in FIG. 5, which will be described later, the packing 16 is deformed in a direction in which the inner diameter of the U-shaped inner leg portion 16a comes into contact with the large diameter portion 12a of the shaft 12 and expands. It acts so as to effectively seal with the large diameter portion 12a of the shaft 12.

Further, as shown in FIG. 3, the contact portion 16c to the casing 10 is formed in a disk shape continuously with the outer leg portion 16b formed in the U shape of the packing 16.
On the front surface and the back surface of the disk-shaped contact portion 16c, protrusions 16d and 16e having an arcuate cross section are integrally formed with the packing 16.
In this embodiment, the protrusions 16d and 16e are continuously formed in a ring shape along the circumferential direction of the disk-shaped contact portion 16c.
Further, a recess 16f is formed along the circumference on the back surface side of the connecting portion between the outer leg portion 16b of the packing 16 and the abutting portion 16c, which faces the packing holder 17 side.

FIG. 4 shows an enlarged cross-sectional view of the ring-shaped packing holder 17 cut along a plane orthogonal to the circumferential direction, and the packing holder 17 is provided along the inner peripheral surface on the front surface (upper surface) side thereof. , A housing portion 17a for accommodating the U-shaped inner peripheral portion of the packing 16 is formed.
Then, a pressure contact portion 17b protruding stepwise is formed on the outside of the accommodating portion 17a in a ring shape, and a pressure contact portion is formed between the accommodating portion 17a and the pressure contact portion 17b along the inside of the pressure contact portion 17b. A ring-shaped projecting portion 17c is formed so as to project slightly forward of the 17b.
Further, on the back surface side of the packing holder 17, a flat spring receiving portion 17d is formed in a ring shape along the outer circumference thereof, and as described above, the front end portion of the return spring 11 is in contact with the spring receiving portion 17d. Be touched.

FIG. 5 shows an enlarged state in which the packing 16 and the packing holder 17 are assembled to the front end portion in the casing 10. That is, the packing holder 17 supports the packing 16 on the front side and receives contact with the return spring 11 that urges the shaft 12 in the backward direction on the back side.
Then, the pressure-welding portion 17b of the packing holder 17 receives the urging force of the return spring 11 and press-contacts the contact portion 16c of the packing 16 so that the front surface of the contact portion 16c is brought into close contact with the inner wall surface of the front end portion of the casing 10. Acts like.

At this time, the front and back protrusions 16d and 16e formed on the packing contact portion 16c are pressure-welded to the packing holder 17 from the state of protruding from the contact portion 16c as shown by the broken line in FIG. It is flattened by receiving force. This contributes to more effectively improving the sealing action between the contact portion 16c and the casing 10.
Therefore, according to this embodiment, the single packing 16 formed in a ring shape provides good sealing performance in two places, between the shaft 12 (the large diameter portion 12a of the shaft) and the casing 10. Can be secured.

Expanding the other hand, by the action of the thermo-element 6 by kicking receive heat from for example, an engine, to receive the shaft 12 (large-diameter portion 12a) moves forward, the spring 11 returns back 17d of the packing holder 17, as shown in FIG. 5 The opening pressure will also increase, and this expanding pressure will be applied to the disc-shaped contact portion 16c of the packing 16. As a result, the rubber meat portion compressed in the axial direction of the contact portion 16c expands in the direction perpendicular to the axis.

At this time, since the ring-shaped protrusion 17c formed on the packing holder 17 has entered the recess 16f on the back surface side of the packing 16, the U-shaped portion formed on the inner peripheral side of the packing 16 is described above. The influence of the elastic deformation behavior of the contact portion 16c of the packing 16 can be effectively prevented. As a result, the fluctuation of the sliding pressure of the packing 16 from the U-shaped inner leg portion 16a to the large diameter portion 12a of the shaft can be kept within a certain range, and the sealing pressure of the shaft 12 moving in the axial direction can be kept within a certain range. Stability can be ensured.

Further, as shown in FIG. 5, the ring-shaped packing holder 17 moves relative to the large diameter portion 12a of the shaft, and a part of the packing holder 17 slides along the large diameter portion 12a. Acts on.
In the embodiment, a composite material in which polyphenylene sulfide is filled with carbon fiber and a filler is used as the material constituting the shaft 12 (large diameter portion 12a), preferably PPS- (CF + MH) 50, and its Rockwell hardness. Is approximately HRM105.
Further, as a material constituting the packing holder 17, a composite material in which polyphenylene sulfide is filled with Teflon (registered trademark) and a filler is used, preferably PPS-PTFE-MH30, and its Rockwell hardness is approximately HRM75. Is.

That is, in this embodiment, a material having a higher hardness of the shaft 12 is used with respect to the packing holder 17. As a result, the degree of wear on the shaft 12 side of the shaft 12 and the packing holder 17 that are in sliding contact with each other can be reduced.
As a result, it is possible to provide a thermoactor that can reduce the change with time in the sealing property of the packing 16 that is always in sliding contact with the shaft 12.

Further, in the embodiment described above, the disc-shaped contact portions 16c provided on the packing 16 have protrusions 16d and 16e having an arcuate cross section on the front surface and the back surface, respectively, along the circumferential direction. It is formed in a ring shape. As another embodiment, the front and back protrusions 16d and 16e formed on the packing contact portion 16c are between the shaft 12 (the large diameter portion 12a of the shaft) and the casing 10. As long as good sealing performance can be ensured at two places, the configuration may be such that only the protrusions 16d are provided or only the protrusions 16e are provided, and the protrusions 16d and 16e may not be provided.

The embodiment described above exemplifies a thermoactuator driven by a thermoelement, but the seal structure according to the present invention is not limited to the thermoactuator, and can be used for other actuators to have the same effect. Can be obtained.

1 Thermoactuator 2 Wax 3 Element case 4 Retainer 5 Support part 5a Flange part 6 Thermoelement 7 Guide part 8 Piston 9 Diaphragm 10 Casing 10a Casing body 10b Flange 10c Through hole 10d Base end opening 10e Front end opening 11 Return spring 12a Large diameter part 12b Hollow part 12c, 4a Flange part 15 O-ring 13, 16 Packing 16a Inner leg part 16b Outer leg part 16c Contact part 16d Front side protrusion 16e Back side protrusion 16f Recess 17 Packing holder 17a Storage part 17b Pressure welding part 17c Protruding part 17d Spring receiving part

Claims (3)

A shaft that moves in the axial direction of the actuator and
A casing that covers the shaft along the axial direction,
A packing arranged in a space between the shaft and the casing and arranged around an opening for inserting the shaft formed at the front end of the casing.
It is provided with a packing holder that supports the packing on the front side and receives contact with a return spring that urges the shaft in the backward direction on the back side.
The packing is integrally formed with a sliding contact surface that is in sliding contact with the shaft on the inner peripheral side and a contact portion that is in contact with a part of the inner surface of the front end portion of the casing on the outer peripheral side of the sliding contact surface. In response to the forward action of the packing holder by the return spring, the contact portion of the packing is brought into contact with the inner surface of the front end portion of the casing , and at the same time.
The packing has a cross-sectional shape orthogonal to the circumferential direction formed in a U shape on the inner peripheral side, and the U-shaped inner leg portion is a sliding contact surface that is in sliding contact with the shaft, and is a sliding contact surface on the outer side of the U shape. A contact portion with the casing is formed in a disk shape continuously on the leg portion.
A seal structure for an actuator, characterized in that a protrusion protruding in the axial direction of the actuator is integrally formed with the packing on at least one of the front surface and the back surface of the contact portion . On the back surface of the packing, a recess is formed along the circumference in the connecting portion between the U-shaped outer leg portion and the contact portion with the casing, and the packing holder is formed in the recess formed in the packing. The seal structure for an actuator according to claim 1 , wherein a protruding portion to be fitted is formed on the front surface side. The seal structure for an actuator according to claim 1, wherein the material of the shaft has a hardness higher than that of the material of the packing holder.

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