Electronic throttle device and anodizing method

Abstract

To secure reliability of an electronic throttle device by achieving both corrosion suppression of a bore inner wall of a housing and sufficient heat radiation performance of heat generation of a motor.SOLUTION: An electronic throttle device 1 comprises: a throttle body 11 including a bore 11a; a valve shaft 3 that is rotatably supported by the throttle body 11 and partially disposed in the bore 11a; a throttle valve 4 that is disposed in the bore 11a and fixed to the valve shaft 3; a DC-motor 5 that is provided in the throttle body 11 and rotationally drives the valve shaft 3; and a motor housing part 11c that is provided integrally with the throttle body 11 for housing the DC-motor 5. In the throttle body 11, only at least a part of an inner wall of the bore 11a is covered with an anodic oxide film 20, and a raw material is exposed in the other part.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to an electronic throttle device used to adjust the amount of intake air in an engine and an anodizing method related thereto. [Background technology]

[0002] A known example of this type of technology is the "air control valve device" described in Patent Document 1 below. This device includes an intake cylinder with an intake passage (bore), a valve stem that passes through the bore and has both ends rotatably supported on the walls of the intake cylinder, and a throttle valve that is fixed to the valve stem and installed in the bore. If rust occurs on the end of the throttle valve or on the inner wall of the bore, in the worst case scenario, the throttle valve may become stuck to the inner wall of the bore. Therefore, this technology forms a rust-preventive coating on at least one of the inner wall of the bore and the throttle valve. The technology discloses an anodic oxide coating formed by anodizing (alumite treatment) as the rust-preventive coating.

[0003] On the other hand, an electronic throttle device is known in which the above device is electrically driven by a drive device including a motor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-51201 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the device described in Patent Document 1, when anodizing (anodizing) the inner wall of the intake cylinder bore, the entire surface of the housing including the intake cylinder is typically treated. However, if anodizing is performed on the entire surface of the housing constituting the electronic throttle device, an anodized film is formed on the entire surface. The heat-shielding properties of the anodized film make it difficult for heat from the drive device, including the motor, to be transmitted to the housing, resulting in insufficient heat dissipation from the drive device and potentially causing malfunctions in the electronic throttle device. Furthermore, if anodizing is performed on the entire surface of the housing, it is difficult to form an anodized film of uniform thickness on the inner wall of the bore.

[0006] The present disclosure was made in consideration of the above circumstances, and its purpose is to ensure reliability by suppressing corrosion on the inner wall of the housing bore and by providing sufficient heat dissipation for the heat generated by the motor in an electronic throttle device. Another purpose of the present disclosure is to provide an anodizing method that can form a uniformly thick anodized film on the inner wall of the bore that contributes to corrosion suppression. [Means for solving the problem]

[0007] In order to achieve the above object, the technology described in claim 1 comprises a housing including a bore through which a gas flows, a valve stem rotatably supported by the housing and with a portion thereof disposed within the bore, a throttle valve disposed within the bore and fixed to the valve stem, a motor provided in the housing for rotating the valve stem, and a motor accommodating section provided integrally with the housing for accommodating the motor. 、 In an electronic throttle device comprising: the inner wall of the bore is metal; The housing has an inner wall of the bore. One Only the part is covered with an anodized film, and the other parts are bare. When the throttle valve is fully closed, the anodic oxide coating is formed on the portion of the inner wall of the bore that faces the throttle valve. The purpose of this is to

[0008] According to the configuration of the above technology, at least a portion of the inner wall of the bore of the housing is covered with an anodized coating, so that corrosion between the inner wall of the bore and the throttle valve is suppressed by the anodized coating. One Only the portion is covered with an anodized film, and the material is exposed in other portions including the inside and outside of the motor housing portion, so that heat generated by the motor can be transferred and released in other portions.

[0009] In order to achieve the above object, the technology described in claim 2 is an electronic throttle device described in claim 1, in which the inner wall of the bore includes a flow rate adjusting portion that faces the outer peripheral end face of the throttle valve when the throttle valve is fully closed to adjust the flow rate of gas, and the anodized coating has a uniform film thickness at least in the flow rate adjusting portion.

[0010] According to the configuration of the above technology, in addition to the effect of the technology described in claim 1, the anodized film covers at least the flow rate adjusting portion on the inner wall of the bore, so corrosion at least in the flow rate adjusting portion is suppressed by the anodized film. Also, because the anodized film covering the flow rate adjusting portion has a uniform thickness, a precise and uniform gap is obtained between the flow rate adjusting portion and the throttle valve when fully closed.

[0011] In order to achieve the above object, the technology described in claim 3 is an anodizing method for forming an anodized film in the electronic throttle device described in claim 1 or 2, wherein the housing includes two openings at both ends of the bore and an axial hole through which the valve stem is inserted, and includes the steps of sealing at least one of the openings and the axial hole with a plug, arranging a cathode in the axial direction approximately at the center of the bore after sealing and wiring the housing as an anode, pouring an anodizing solution into the bore, and forming an anodized film on the inner wall of the bore by passing electricity between the anode and cathode after pouring.

[0012] According to the configuration of the above technology, in addition to the effects of the technology described in claim 1 or 2, the cathode is arranged in the axial direction of the approximate center of the bore and the housing is wired as the anode, so the distance between the cathode and the inner wall of the bore, which acts as the anode, is uniform and shortest. Also, in order to form an anodized film on the inner wall of the bore, it is possible to adopt a process of introducing an anodizing solution only into the bore.

[0013] In order to achieve the above object, the technology described in claim 4 is: The valve comprises a housing including a bore through which a gas flows, a valve stem rotatably supported by the housing and with a portion thereof disposed within the bore, a throttle valve disposed within the bore and fixed to the valve stem, a motor provided within the housing for rotating the valve stem, and a motor accommodating section integrally provided within the housing for accommodating the motor, and at least a portion of the inner wall of the bore is covered with an anodized coating. An anodizing treatment method for forming the anodized film in an electronic throttle device, wherein the housing includes two openings at both ends of the bore and a shaft hole through which the valve stem is inserted, the method comprising the steps of: sealing the shaft hole with a plug; arranging a cathode in the axial direction substantially at the center of the bore after the sealing and wiring the housing as an anode; immersing the housing in an anodizing treatment solution after the wiring; and forming the anodized film on the inner wall of the bore by passing current between the anode and the cathode after the immersion. 、 The purpose is to provide the following.

[0014] According to the configuration of the above technology , distribution After wiring, the housing is immersed in an anodizing solution, and the anodized film is formed by the contact between the inner wall of the bore, which becomes the anode when current is applied, and the cathode. In between Therefore, it is possible to minimize the seals required for the housing. [Effects of the Invention]

[0015] According to the technology described in claim 1, the electronic throttle device can achieve both corrosion prevention of the inner wall of the bore of its housing and sufficient heat dissipation of heat generated by the motor, thereby ensuring the reliability of the electronic throttle device.

[0016] According to the technology described in claim 2, in addition to the effect of the technology described in claim 1, the amount of gas leaking between the flow rate adjusting section and the throttle valve when the electronic throttle device is fully closed can be reduced.

[0017] According to the technology described in claim 3, in addition to the effects of the technology described in claim 1 or 2, it is possible to form a relatively thick and uniform anodic oxide film on the inner wall of the bore, which contributes to corrosion inhibition. Also, it is possible to form the anodic oxide film on the inner wall of the bore using compact equipment or devices.

[0018] According to the technology described in claim 4 , Ha The sealing process required for the housing can be simplified. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view showing an electronic throttle device according to a first embodiment. [Figure 2] FIG. 2 is a front view showing the electronic throttle device in the first embodiment. [Figure 3] 3 is a cross-sectional view taken along line AA in FIG. 2 showing the electronic throttle device according to the first embodiment. [Figure 4] 4 is a cross-sectional view taken along line BB in FIG. 3 showing the electronic throttle device according to the first embodiment. [Figure 5] FIG. 2 is a perspective view showing a cross section of a valve assembly including a valve stem, a throttle valve, and a bearing, disassembled from a throttle body in the first embodiment. [Figure 6] FIG. 3 is a cross-sectional view showing a simplified view of a bore of a throttle body and a motor housing portion in the first embodiment. [Figure 7] 4 is a flowchart showing the procedure of anodizing treatment according to the first embodiment. [Figure 8] FIG. 3 is a schematic cross-sectional view of the throttle body in a first step of anodizing treatment according to the first embodiment. [Figure 9] FIG. 6 is a schematic cross-sectional view of the throttle body and other components in a third step of anodizing treatment according to the first embodiment. [Figure 10] FIG. 10 is a schematic view showing the state of the throttle body and wiring in a fourth step of the anodizing process according to the first embodiment. [Figure 11]FIG. 10 is a schematic view showing the state of the throttle body, wiring, and anodizing solution in a fifth step of the anodizing process according to the first embodiment. [Figure 12] FIG. 10 is a schematic view showing the state of the throttle body, wiring, and anodizing solution in a sixth step of the anodizing process according to the first embodiment. [Figure 13] FIG. 11 is a schematic cross-sectional view of the throttle body and other components in a tenth step of anodizing treatment according to the first embodiment. [Figure 14] FIG. 11 is a schematic cross-sectional view of the throttle body in an eleventh step of anodizing treatment according to the first embodiment. [Figure 15] 10 is a flowchart showing the procedure of anodizing treatment according to the second embodiment. [Figure 16] FIG. 11 is a schematic cross-sectional view of the throttle body and other components in a third step of anodizing treatment according to the second embodiment. [Figure 17] FIG. 10 is a schematic view showing the state of the throttle body and wiring in a fourth step of the anodizing process according to the second embodiment. [Figure 18] FIG. 10 is a schematic view showing the state of the throttle body, wiring, and anodizing solution in a fifth step of the anodizing process according to the second embodiment. [Figure 19] FIG. 10 is a schematic view showing the state of the throttle body, wiring, and anodizing solution in a sixth step of anodizing treatment according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying an electronic throttle device and an anodizing method related thereto will now be described.

[0021] First Embodiment First, a first embodiment will be described in detail with reference to the drawings. The electronic throttle device of each embodiment described below is provided in an intake passage of an automobile engine and is used to adjust the amount of intake air into the engine.

[0022] [Configuration of electronic throttle device] Fig. 1 shows an oblique view of an electronic throttle device 1 of this embodiment. Fig. 2 shows the same electronic throttle device 1 in a front view. Fig. 3 shows the same electronic throttle device 1 in a cross-sectional view taken along line AA in Fig. 2. Fig. 4 shows the same electronic throttle device 1 in a cross-sectional view taken along line BB in Fig. 3 (the DC motor 5 and the like are not cross-sectional). As shown in Figs. 1 to 4, the electronic throttle device 1 comprises, as its main components, a housing 2, a valve stem 3, a throttle valve 4, a DC motor 5, and a reduction mechanism 6.

[0023] As shown in FIGS. 1 to 4, in this embodiment, the housing 2 includes a metal (aluminum) throttle body 11 and a resin gear cover 12. The throttle body 11 includes a bore 11a that communicates with the engine's intake passage and through which intake air flows, a gear housing 11b that houses the reduction mechanism 6, and a motor housing 11c that houses a DC motor. The gear cover 12 covers the opening of the gear housing 11b. The valve shaft 3 is rotatably supported by the throttle body 11 via bearings 13 and 14, and a portion of the valve shaft 3 is disposed within the bore 11a. In this embodiment, the valve shaft 3 passes through the bore 11a in the throttle body 11, and both ends of the valve shaft 3 are rotatably supported via the bearings 13 and 14. The bore 11a has a circular cross section. The throttle valve 4 is disk-shaped, disposed within the bore 11a, and fixed to the valve shaft 3. The throttle valve 4, fixed to the valve shaft 3, rotates around the valve shaft 3, forming a so-called butterfly valve. The rotation of the throttle valve 4 opens and closes the bore 11a, thereby adjusting the amount of intake air flowing through the bore 11a. The DC motor 5 is provided in the motor housing portion 11c to rotate the valve shaft 3.

[0024] The gear cover 12 is fixed to the throttle body 11 with a plurality of rivets 15. A throttle sensor 16 for detecting the opening degree (throttle opening degree) of the throttle valve 4 is provided inside the gear cover 12, corresponding to one end of the valve stem 3. A connector 17 for wiring is provided on the gear cover 12.

[0025] 3 and 4, a throttle gear 21 is fixed to one end of the valve shaft 3. A return spring 18 is provided between the throttle gear 21 and the throttle body 11 to bias the throttle valve 4 in the closing direction.

[0026] As shown in FIG. 4, a motor gear 22 is fixed to the motor shaft 5a of the DC motor 5. The DC motor 5 is drivingly connected to the valve shaft 3 via a speed reduction mechanism 6 to drive the throttle valve 4 in the opening direction. In this embodiment, the speed reduction mechanism 6 includes a throttle gear 21, a motor gear 22, an intermediate shaft 19 arranged between the DC motor 5 and the valve shaft 3, and an intermediate gear 23 rotatably provided on the intermediate shaft 19 and transmitting the rotational force of the motor gear 22 to the throttle gear 21. The motor gear 22 is connected to the throttle gear 21 via the intermediate gear 23. The intermediate gear 23 is a two-stage gear including a large-diameter gear 23a and a small-diameter gear 23b, and is rotatably supported on the throttle body 11 via the intermediate shaft 19. The motor gear 22 is connected to the large-diameter gear 23a, and the throttle gear 21 is connected to the small-diameter gear 23b.

[0027] In the electronic throttle device 1 of this embodiment, the driving force of the DC motor 5 rotates the valve stem 3 in the forward direction from the fully closed state of the throttle valve 4 (the state shown in FIGS. 1 to 4), causing the motor gear 22 to rotate, and the rotational force is reduced by the intermediate gear 23 and transmitted to the throttle gear 21. Then, the valve stem 3 and the throttle valve 4 rotate against the biasing force of the return spring 18, opening the bore 11a and opening the throttle valve 4. Furthermore, in order to hold the throttle valve 4 at a certain opening degree, a rotational force is generated by the DC motor 5, and this rotational force is transmitted to the valve stem 3 and the throttle valve 4 via the motor gear 22, intermediate gear 23, and throttle gear 21 as a holding force. When this holding force balances the biasing force of the return spring 18, the throttle valve 4 is held at a certain opening degree. On the other hand, when the DC motor 5 is stopped from this held state, the throttle gear 21 rotates in the reverse direction due to the biasing force of the return spring 18, and the valve stem 3 and throttle valve 4 rotate in the reverse direction due to this rotational force, closing the throttle valve 4 to the default position. Then, the valve stem 3 is further rotated in the reverse direction by the driving force of the DC motor 5, and the throttle valve 4 closes to the fully closed position.

[0028] [Anodic oxide coating on throttle body (aluminum oxide coating)] Here, if rust occurs on the end of the throttle valve 4 and the inner wall of the bore 11a, there is a risk that the throttle valve 4 will stick to the inner wall of the bore 11a. Therefore, in this embodiment, to prevent the throttle valve 4 from sticking due to rust, an anodized coating (aluminum oxide coating) 20 is provided as a rust-preventive coating on the inner wall of the bore 11a of the aluminum throttle body 11.

[0029] FIG. 5 shows a perspective view of a valve assembly, including the valve stem 3, throttle valve 4, and bearings 13 and 14, disassembled from the throttle body 11. FIG. 6 shows a simplified cross-sectional view of the bore 11a and motor housing 11c of the throttle body 11. As shown in FIGS. 1, 3, 5, and 6, only a portion of the inner wall of the bore 11a of the throttle body 11 is covered with an anodized coating 20, with the remaining portions of the bore 11a being exposed. That is, the inner wall of the bore 11a includes a flow rate adjusting portion 8 that faces the outer peripheral end face of the throttle valve 4 when the throttle body 11 is fully closed to adjust the intake air volume (gas flow rate). As shown in FIGS. 1 and 5, the flow rate adjusting portion 8 has a slightly smaller inner diameter than the rest of the inner wall of the bore 11a and is slightly raised in an annular shape. In this embodiment, the anodized coating 20 is formed on the surface of the flow rate adjusting portion 8 with a uniform thickness (e.g., 4 to 5 μm). In this embodiment, the throttle body 11 includes two openings 11aa, 11ab that open to both ends of the bore 11a, and two axial holes 11d, 11e through which the valve stem 3 passes. The flow rate adjustment portion 8 has a predetermined width in the axial direction of the bore 11a so as to encompass the two axial holes 11d, 11e within the bore 11a. The anodic oxide coating 20 is provided to cover the flow rate adjustment portion 8.

[0030] [Anodizing method] Next, we will explain the anodizing method (anodizing method) for forming the anodic oxide film 20 on the inner wall of the bore 11a of the throttle body 11. Fig. 7 is a flowchart showing the anodizing procedure. Figs. 8 to 14 are schematic diagrams showing some of the steps constituting the anodizing process.

[0031] In the anodizing method of this embodiment, first, as shown in Fig. 7 as a first step S1, the aluminum throttle body 11 is degreased by a well-known method. At this time, as shown in Fig. 8, the openings 11aa, 11ab and the shaft holes 11d, 11e of the throttle body 11 remain open.

[0032] Next, as shown in the second step S2 in FIG. 7, the degreased throttle body 11 is washed with water.

[0033] Next, as shown in the third step S3 in Fig. 7, the opening 11ab and the axial holes 11d and 11e of the water-washed throttle body 11 are sealed with plugs 31 and 32, respectively. That is, as shown in Fig. 9, the opening 11ab on the lower side of the throttle body 11 is sealed with a rubber plug 31, and both axial holes 11d and 11e are sealed with rubber plugs 32. Here, a hole 31a penetrating in the axial direction is formed in the center of the plug 31.

[0034] Next, as shown in FIG. 7 as a fourth step S4, a cathode is placed in the bore 11a of the sealed throttle body 11, and an anode is wired to the throttle body 11. That is, as shown in FIG. 10, a rod-shaped cathode 41 is placed through the hole 31a of the lower plug 31. Here, the upper part of the cathode 41 is inserted approximately halfway in the axial direction of the bore 11a, and the lower part of the cathode 41 protrudes below the plug 31. Then, a negative wire 42 connected to the lower end of the cathode 41 is connected to the negative terminal of a power source 43, and a positive wire 44 connected to the positive terminal of the power source 43 is connected to the throttle body 11. As a result, the inner wall of the bore 11a serves as an anode 45, with the cathode 41 located at the center of the bore 11a. A power switch 46 is attached to the positive wire 44. In this embodiment, a rod-shaped cathode 41 is placed at the center of a bore 11a having a circular cross section, and the inner wall of the bore 11a serves as an anode 45, so that the inter-electrode distance between the cathode 41 and the anode 45 is uniform and minimized. In this embodiment, a stirrer 33 that can rotate around the cathode 41 is installed inside the bore 11a to stir an anodizing treatment solution 34, which will be described later. The stirrer 33 includes a plurality of blades 33a that rotate around the cathode 41.

[0035] Next, as shown in a fifth step S5 in Fig. 7, an anodizing treatment solution (electrolyte) is poured into the bore 11a. That is, as shown in Fig. 11, an anodizing treatment solution 34 is poured into the bore 11a from an upper opening 11aa of the bore 11a, and the liquid level 34a is aligned with the upper end of the cathode 41.

[0036] Next, as shown in FIG. 7 as a sixth step S6, with the anodizing solution 34 poured into the bore 11a, electricity is passed between the anode 45 and the cathode 41 to form the anodized film 20 on the inner wall of the bore 11a (anodizing). That is, as shown in FIG. 12, the power switch 46 is turned on, and electricity is passed through the aluminum inner wall of the bore 11a in the anodizing solution 34. This forcibly oxidizes the inner wall of the bore 11a, coating the inner wall of the bore 11a with an anodized film 20 that is thicker and stronger than in its natural state. At this time, the anodizing solution 34 in the bore 11a is stirred by the stirrer 33, thereby making the temperature of the anodizing solution 34 uniform within the bore 11a.

[0037] Next, as shown in the seventh step S7 in FIG. 7, the workpiece including the anodized throttle body 11 is washed with water.

[0038] Next, as shown in the eighth step S8 in Fig. 7, the throttle body 11 that has been washed with water is subjected to a pore sealing treatment. That is, the micropores that have formed on the surface of the material of the throttle body 11 are sealed, and the surface is made smooth.

[0039] Next, as shown in the ninth step S9 in FIG. 7, the throttle body 11 that has been subjected to the sealing treatment is washed with water.

[0040] Next, as shown in Fig. 7 as a tenth step S10, the cathode 41, the wiring 42, 44, and the power switch 46 are removed from the rinsed throttle body 11. Fig. 13 is a schematic cross-sectional view of the throttle body 11 and plugs 31, 32 in this removed state. In Fig. 13, an anodic oxide coating 20 is formed on the inner wall of the bore 11a from the plug 31 of the lower opening 11ab to the position where the liquid level 34a of the anodizing treatment solution 34 was located.

[0041] Next, as shown in Fig. 7 as an eleventh step S11, the plugs 31 and 32 are removed from the throttle body 11 from which the cathode 41 and other components have been removed. Fig. 14 is a schematic cross-sectional view of the throttle body 11 in this removed state. In Fig. 14, an anodic oxide coating 20 is formed in the bore 11a, centered on the axial holes 11d and 11e, in a manner corresponding to the flow rate adjusting portion 8.

[0042] Next, as shown in a twelfth step S12 in FIG. 7, the throttle body 11 from which the plugs 31 and 32 have been removed is dried.

[0043] Finally, as shown in a thirteenth step S13 in FIG. 7, the throttle body 11 after drying is inspected and the anodizing process is completed.

[0044] The anodizing method described above includes the steps of sealing one opening 11ab and two axial holes 11d, 11e of the throttle body 11 (housing) with plugs 31, 32, placing a cathode 41 approximately in the axial center of the bore 11a after the sealing and wiring the throttle body 11 (housing) as an anode 45, pouring anodizing solution 34 into the bore 11a after the wiring, and forming an anodized coating 20 on the inner wall of the bore 11a by passing electricity between the anode 45 and the cathode 41 after the pouring.

[0045] [Action and effect of electronic throttle device] According to the configuration of the electronic throttle device 1 of this embodiment described above, a portion of the inner wall of the bore 11a of the throttle body 11 that constitutes the housing 2 is covered with the anodized film 20, and therefore corrosion between the inner wall of the bore 11a and the throttle valve 4 is suppressed by the anodized film 20. Also, in the throttle body 11, only a portion of the inner wall of the bore 11a is covered with the anodized film 20, and other portions, including the inside and outside of the motor accommodating portion 11c, are exposed, allowing the transfer and release of heat from the DC motor 5 in other portions. Therefore, for the electronic throttle device 1, corrosion of the inner wall of the bore 11a of the throttle body 11 (housing) can be suppressed, and both the corrosion suppression and sufficient heat dissipation of heat from the DC motor 5 can be achieved, ensuring the reliability of the electronic throttle device 1.

[0046] According to the configuration of this embodiment, the anodized film 20 covers the flow rate adjustment portion 8 on the inner wall of the bore 11a, and therefore corrosion of the flow rate adjustment portion 8 is suppressed by the anodized film 20. Furthermore, because the anodized film 20 covering the flow rate adjustment portion 8 has a uniform thickness, a precise and uniform gap is obtained between the flow rate adjustment portion 8 and the throttle valve 4 when the throttle valve is fully closed. Therefore, with the electronic throttle device 1, it is possible to reduce the amount of intake air (gas) leaking between the flow rate adjustment portion 8 and the throttle valve 4 when the throttle valve is fully closed.

[0047] [Actions and effects of anodizing treatment method] According to the anodizing method of this embodiment described above, the cathode 41 is positioned approximately at the axial center of the bore 11a, and the throttle body 11 (housing) is wired as the anode 45. This ensures a uniform and shortest distance between the cathode 41 and the inner wall of the bore 11a, which serves as the anode 45. This allows the anodized coating 20, which contributes to corrosion inhibition, to be formed with a uniform thickness on the inner wall of the bore 11a. Furthermore, to form the anodized coating 20 on the inner wall of the bore 11a, a process can be adopted in which the anodized coating solution 34 is introduced only into the bore 11a. This allows the anodized coating 20 to be formed on the inner wall of the bore 11a using compact equipment or facilities. This is evident from the fact that the anodized coating method of this embodiment does not require the liquid tank 37 (see FIGS. 18 and 19 ) for storing the anodized coating solution 34, as described later.

[0048] According to the configuration of this embodiment, during the anodizing process, the temperature of the anodizing solution 34 in the bore 11a can be made uniform by stirring the anodizing solution 34 with the stirrer 33. This makes it possible to uniformly increase the temperature of the inner wall of the bore 11a that comes into contact with the anodizing solution 34, thereby making it possible to increase the thickness of the anodized coating 20 more uniformly.

[0049] Second Embodiment Next, the second embodiment will be described in detail with reference to the drawings. In the following description, the same components as those in the first embodiment will be denoted by the same reference numerals and will not be described again, and differences will be mainly described.

[0050] This embodiment differs from the first embodiment in the content of the anodizing treatment method (anodizing treatment method). Figure 15 is a flowchart showing the procedure of the anodizing treatment. Figures 16 to 19 are schematic diagrams showing some of the steps constituting the anodizing treatment.

[0051] [Anodizing method] The anodizing method (anodizing method) of this embodiment will be described below. The procedure shown in the flowchart of Fig. 15 is composed of the first step S1 to the thirteenth step S13, similar to the processing method of the first embodiment shown in the flowchart of Fig. 7, but also includes steps S1, S2, S6, S11 to S13 that are similar to the method of the first embodiment, and steps S3 to S5 and S7 to S10 that are different in content.

[0052] That is, as shown in Fig. 15, after performing the first step S1 and the second step S2 similar to those in the first embodiment, in this embodiment, as shown in the third step S3, the axial holes 11d and 11e of the throttle body 11 that has been washed with water are each sealed with a plug. That is, as shown in Fig. 16, both axial holes 11d and 11e of the throttle body 11 are sealed with rubber plugs 32. In this embodiment, the opening 11ab is not sealed with plug 31.

[0053] Next, as shown in FIG. 15 as a fourth step S4, a cathode is placed in the bore 11a of each sealed throttle body 11, and an anode is wired to the throttle body 11. In this embodiment, as shown in FIG. 17, two throttle bodies 11 are paired, and a rod-shaped cathode 41 is inserted vertically into the bore 11a of each throttle body 11 through the upper opening 11aa. The outer periphery of the cathode 41 is mostly covered with a tube 36 made of an insulating material, while the lower portion is not covered by the tube 36. In FIG. 17, the upper portion of each cathode 41 protrudes upward from the bore 11a, and a negative wire 42 connected to the upper end is connected in parallel to the negative terminal of a power source 43. A positive wire 44, connected in parallel to the positive terminal of the power source 43, is connected to each throttle body 11. A power switch 46 is attached to the positive wire 44. Thus, the cathode 41 is located at the center of the bore 11a, and the inner wall of the bore 11a serves as an anode 45. Within bore 11a, electricity can flow between the portion of cathode 41 exposed in bore 11a and the opposing inner wall of bore 11a. In this embodiment, the exposed portion of cathode 41 is positioned so as to correspond to flow rate adjuster 8 on the inner wall of bore 11a. In this embodiment as well, rod-shaped cathode 41 is positioned at the center of bore 11a, which has a circular cross section, and the inner wall of bore 11a serves as anode 45, so the inter-electrode distance between cathode 41 and anode 45 is uniform and minimized.

[0054] Next, as shown in the fifth step S5 in Fig. 15, the workpiece including the two wired throttle bodies 11 etc. is immersed in anodizing solution 34 (electrolyte). That is, as shown in Fig. 18, the two wired throttle bodies 11 are immersed in anodizing solution 34 stored in a liquid tank 37.

[0055] Next, as shown in sixth step S6 in Figure 15, while the workpiece is immersed in anodizing solution 34, electricity is passed between anode 45 and cathode 41 to form an anodic oxide film on the inner wall of bore 11a (anodizing treatment). That is, as shown in Figure 19, power switch 46 is turned on, and electricity is passed through the aluminum inner wall of bore 11a, which faces the lower part of cathode 41 exposed in anodizing solution 34, in anodizing solution 34. This forcibly oxidizes the inner wall of bore 11a, coating the inner wall of bore 11a with an anodic oxide film 20 that is thicker and stronger than in its natural state.

[0056] Next, as shown in the seventh step S7 in FIG. 15, the workpiece is removed from the anodizing solution 34 (electrolyte), and the cathode 41, the wires 42, 44, and the power switch 46 are removed from each of the anodized throttle bodies 11.

[0057] Next, as shown in an eighth step S8 in FIG. 15, each throttle body 11 from which the cathode 41 etc. has been removed is washed with water.

[0058] Next, as shown in the ninth step S9 in FIG. 15, each throttle body 11 that has been washed with water is subjected to a sealing treatment.

[0059] Next, as shown in a tenth step S10 in FIG. 15, each throttle body 11 that has been subjected to the sealing treatment is washed with water.

[0060] Next, as shown in an eleventh step S11 in FIG. 15, the plugs 31 and 32 are removed from the throttle bodies 11 that have been washed with water (see FIG. 14).

[0061] Next, as shown in a twelfth step S12 in FIG. 15, each throttle body 11 from which the plugs 32 have been removed is dried.

[0062] Finally, as shown in a thirteenth step S13 in FIG. 15, each throttle body 11 after drying is inspected, and the anodizing process is completed.

[0063] The anodizing method described above includes the steps of sealing the axial holes 11d, 11e of the throttle body 11 (housing) with plugs 32, positioning a cathode 41 approximately in the axial center of the bore 11a after sealing and wiring the throttle body 11 as an anode 45, immersing the throttle body 11 in anodizing solution 34 after wiring, and forming an anodized coating 20 on the inner wall of the bore 11a by passing electricity between the anode 45 and the cathode 41 after immersion.

[0064] [Actions and effects of anodizing treatment method] According to the anodizing method of this embodiment described above, the throttle body 11 (housing) is immersed in the anodizing solution 34 after wiring, and the anodized film 20 is formed only between the cathode 41 and the inner wall of the bore 11a, which becomes the anode 45 when current is applied. This makes it possible to minimize the sealing required for the throttle body 11. Specifically, in the third step S3 of this embodiment, the two shaft holes 11d and 11e are sealed with plugs 32. However, unlike the anodizing method of the first embodiment, sealing the lower opening 11ab of the bore 11a with plug 31 can be omitted. This simplifies the sealing process required for the throttle body 11 (housing).

[0065] <Another embodiment> The disclosed technology is not limited to the above-described embodiments, and can be implemented by appropriately modifying part of the configuration within the scope of the disclosed technology.

[0066] (1) In the first embodiment, the cathode 41 and the anode 45 for one throttle body 11 are electrically connected to the power supply 43. However, the cathodes and anodes for multiple throttle bodies may be connected in parallel to the power supply. In this case, multiple throttle bodies can be configured to be anodized simultaneously.

[0067] (2) In the first embodiment, the plug 31 is provided at one opening 11ab of the bore 11a. The other opening of the bore may be plugged.

[0068] (3) In the first embodiment, the cathode 41 is provided on the plug 31 of one opening 11ab of the bore 11 from the side of the opening 11ab. However, it is also possible to not provide a cathode on this plug, and instead insert the cathode into the bore from the side of the other opening of the bore.

[0069] (4) In the second embodiment, the cathode 41 and anode 45 of each of the two throttle bodies 11 are connected in parallel to the power supply 43. However, the cathodes and anodes of three or more throttle bodies may be connected in parallel to the power supply, or the cathode and anode of one throttle body may be electrically connected to the power supply.

[0070] (5) In the above embodiments, the anodized coating 20 is provided on a portion of the inner wall of the bore 11a of the throttle body 11. However, the anodized coating may be provided on almost the entire inner wall of the bore.

[0071] (6) In each of the above embodiments, the valve stem 3 passes through the bore 11a of the throttle body 11, and both ends of the valve stem 3 are rotatably supported at both ends via the bearings 13, 14. However, the throttle body may be configured so that one end of the valve stem is disposed in the bore, and the other end is rotatably supported at one end via the bearing. [Industrial Applicability]

[0072] The disclosed technology can be used in manufacturing electronic throttle devices used in gasoline engines and their throttle bodies (housings). [Explanation of symbols]

[0073] 1 Electronic throttle device 2. Housing 3 Valve stem 4 Throttle valve 5 DC motors 8 Flow rate adjustment section 11 Throttle body (housing) 11a Bore 11aa opening 11ab opening 11b Gear housing 11c Motor housing 11d shaft hole 11e Shaft hole 20 Anodized film 31 Stopper (large) 32 Stopper (small) 34 Anodizing solution 41 Cathode 42 Negative wiring 44 positive wiring 45 Anode

Claims

1. a housing including a bore through which a gas flows; a valve stem rotatably supported by the housing and partially disposed within the bore; a throttle valve disposed within the bore and secured to the valve stem; a motor provided in the housing for rotating the valve shaft; a motor accommodating portion integrally provided with the housing for accommodating the motor; In an electronic throttle device comprising: the inner wall of the bore is metal; The housing has an inner wall of the bore covered with an anodized coating only in part, and the material is exposed in other parts, When the throttle valve is fully closed, the anodic oxide coating is formed on a portion of the inner wall of the bore that faces the throttle valve. An electronic throttle device characterized by:

2. 2. The electronic throttle device according to claim 1, The inner wall of the bore includes a flow rate adjusting portion that faces an outer peripheral end face of the throttle valve when the throttle valve is fully closed to adjust the flow rate of the gas, and the anodic oxide coating has a uniform film thickness at least at the flow rate adjusting portion. An electronic throttle device characterized by:

3. 3. An anodizing method for forming the anodized film in the electronic throttle device according to claim 1 or 2, comprising: The housing includes two openings that open to both ends of the bore and a shaft hole through which the valve shaft is inserted, sealing at least one of the opening and the axial hole with a plug; a step of arranging a cathode in the axial direction of the approximate center of the bore after the sealing and wiring the housing as an anode; introducing an anodizing solution into the bore; a step of applying a current between the anode and the cathode after the charging to form the anodic oxide film on the inner wall of the bore; An anodizing method comprising:

4. A housing including a bore through which a gas flows; a valve stem rotatably supported by the housing and partially disposed within the bore; a throttle valve disposed within the bore and secured to the valve stem; a motor provided in the housing for rotating the valve stem; a motor accommodating portion integrally provided with the housing for accommodating the motor, 1. An anodizing method for forming an anodized film in an electronic throttle device in which at least a portion of an inner wall of the bore is covered with the anodized film, comprising: The housing includes two openings that open to both ends of the bore and a shaft hole through which the valve shaft is inserted, sealing the axial hole with a plug; a step of arranging a cathode in the axial direction of the approximate center of the bore after the sealing and wiring the housing as an anode; immersing the housing in an anodizing solution after the wiring; a step of applying a current between the anode and the cathode after the immersion to form the anodic oxide coating on the inner wall of the bore; An anodizing method comprising:

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