Valve device manufacturing method

Abstract

To provide a method for manufacturing valve device capable of improving sealability between a valve seat and a valve body in a fully closed state.SOLUTION: One aspect of the present disclosure is a method for manufacturing an EGR valve device 1 having a resin seat 4 and a metal valve 5 that comes into contact with and separates from the seat 4, comprising a valve body heating step of heating the valve 5, and a heating valve body pressing step of pressing the valve 5 heated in the valve body heating step against the seat 4.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a method of manufacturing a valve device. [Background technology]

[0002] Patent Document 1 discloses a valve device in which a valve (valve element) opens and closes a flow path by coming into contact with and separating from an annular seat (valve seat). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-71102 Summary of the Invention [Problem to be solved by the invention]

[0004] In a valve device such as that disclosed in Patent Document 1, if the seat is made of resin, the resin is likely to shrink after molding, which may reduce the dimensional accuracy of the seat (for example, accuracy of roundness and inclination).As a result, when the valve abuts against the seat to close the flow path in the fully closed state, a gap may form between the seat and the valve, reducing the sealing performance.

[0005] Therefore, the present disclosure has been made to solve the above-mentioned problems, and aims to provide a method for manufacturing a valve device that can improve the sealing performance between the valve seat and the valve body when fully closed. [Means for solving the problem]

[0006] In order to solve the above-described problems, one aspect of the present disclosure provides a method for manufacturing a valve device having a resin valve seat and a metal valve element that abuts against and separates from the valve seat, the method comprising: a valve element heating step of heating the valve element; and a heated valve element pressing step of pressing the valve element heated in the valve element heating step against the valve seat. the valve device has a valve stem to which the valve element is welded, and the valve element heating step is a welding step of welding the valve element and the valve stem, in which the valve element is sandwiched and fixed between the valve seat and a welding jig, and then the valve element and the valve stem are welded together using a welding electrode, and the valve element is pressed against the valve seat by the welding jig;It is characterized by:

[0007] According to this aspect, the shape of the resin valve seat is changed by pressing the heated valve element against the valve seat. This allows the valve disc to fit the shape of the valve seat. In some cases, the gap between the valve disc and the valve seat can be reduced, so the gap between the valve seat and the valve disc can be reduced. This can improve the cooling performance. Furthermore, since the welding process also serves as the valve body heating process, there is no need to perform a separate valve body heating process in addition to the welding process. As a result, in the method for manufacturing the valve device, it is possible to efficiently improve the sealing performance between the valve seat and the valve body when the valve is fully closed.

[0011] In the above aspect, the heating valve body pressing means To the extent Therefore, it is preferable that the valve body be brought into contact with the annular valve seat over the entire circumferential direction thereof when the valve is fully closed and the valve seat and the valve body are in contact with each other.

[0012] According to this aspect, it is possible to eliminate a gap between the valve disc and the valve seat over the entire circumferential direction of the annular valve seat when the valve is fully closed, thereby more effectively improving the sealing performance between the valve seat and the valve disc when the valve is fully closed. [Effects of the Invention]

[0015] According to the manufacturing method of the valve device of the present disclosure, it is possible to improve the sealing performance between the valve seat and the valve body when the valve is fully closed. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is an overall view of an EGR valve device according to an embodiment of the present invention. [Figure 2] 10A and 10B are diagrams showing how the shaft is set in the manufacturing method of the EGR valve device. [Figure 3] 10A and 10B are diagrams showing how the valve is set in the manufacturing method of the EGR valve device. [Figure 4] 10A and 10B are diagrams showing how an earth jig is set in the manufacturing method of the EGR valve device. [Figure 5]In the method for manufacturing an EGR valve device, this is a diagram showing the state of welding a valve and a shaft and pressing the valve. [Figure 6] This is a diagram showing the state before the shape of the seat conforms to the shape of the valve, and is an image diagram showing the cross-section of the seat, the valve, and the shaft. [Figure 7] This is a diagram showing the state before the shape of the seat conforms to the shape of the valve, and is an image diagram of the seat alone as seen from its lower surface. [Figure 8] This is a diagram showing the state after the shape of the seat conforms to the shape of the valve, and is an image diagram showing the cross-section of the seat, the valve, and the shaft. [Figure 9] This is a diagram showing the state after the shape of the seat conforms to the shape of the valve, and is an image diagram of the seat alone as seen from its lower surface.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the valve device and the method for manufacturing the valve device of the present disclosure will be described. In the following description, the EGR valve device 1 will be described as an example of the valve device.

[0018] <Overview Explanation of the EGR Valve> First, the overview of the EGR valve device 1 will be described. The EGR valve device 1 is provided in an EGR passage (not shown) that flows a part of the exhaust discharged from an engine (not shown) to an intake passage (not shown) as EGR gas in order to reduce it to the engine. And the EGR valve device 1 is used to adjust the flow rate of the EGR gas in the EGR passage.

[0019] As shown in FIG. 1, the EGR valve device 1 has a poppet-type valve structure and includes a housing 3 having a flow path 2 for EGR gas, a seat 4, a valve 5, a shaft 6, a drive unit 7, and a seal member 8. In FIG. 1, parts other than the drive unit 7 are shown by a cross-sectional view.

[0020] The seat 4 is formed in an annular shape and is provided inside the flow path 2 of the housing 3. In the example shown in Fig. 1, the seat 4 is separate from the housing 3 and attached to the housing 3, but is not limited to this and may be provided integrally with the housing 3. The seat 4 is an example of a "valve seat" in the present disclosure.

[0021] The valve 5 is formed in an annular shape (having a substantially umbrella-shaped outer shape) and is provided inside the flow path 2 by being welded to one end of the shaft 6. The valve 5 is disposed below the seat 4 and comes into contact with and separates from the seat 4. The valve 5 is an example of the "valve body" of the present disclosure.

[0022] The shaft 6 is formed in an axial shape and is inserted into the housing 3 so as to be disposed parallel to the central axis of the seat 4. The valve 5 is welded to one axial end of the shaft 6, and a drive unit 7 is connected to the other axial end (not shown). The shaft 6 is supported by a bearing (not shown) so as to be movable in the axial direction. The shaft 6 is an example of a "valve shaft" in the present disclosure.

[0023] The driving unit 7 is configured by, for example, a motor, and is connected to the other end of the shaft 6, and moves the shaft 6 in the axial direction of the shaft 6 (the up and down direction in FIG. 1) together with the valve 5. The sealing member 8 seals the gap between the housing 3 and the shaft 6.

[0024] The EGR valve device 1 configured as described above opens and closes the flow path 2 by using the drive unit 7 to move the shaft 6 together with the valve 5 in the axial direction of the shaft 6, causing the valve 5 to abut against and move away from the seat 4. The EGR valve device 1 also adjusts the amount of movement of the shaft 6 and the valve 5 by the drive unit 7, thereby changing the opening area (opening degree) between the seat 4 and the valve 5 and regulating the flow rate of EGR gas in the flow path 2.

[0025] <Methods for improving the seal between the seat and the valve when fully closed> In this embodiment, the sheet 4 is made of resin. When the sheet 4 is made of resin, the resin is likely to shrink after molding. This may reduce the dimensional accuracy of the sheet 4, particularly the dimensional accuracy (e.g., accuracy of roundness and inclination) of the sealing portion of the sheet 4 that contacts the valve 5. This may result in a gap between the sheet 4 and the valve 5 when the valve 5 contacts the sheet 4 and closes the flow path 2 in the fully closed state, which may reduce the sealing performance between the sheet 4 and the valve 5.

[0026] Therefore, it is conceivable to improve the dimensional accuracy by processing the sheet 4 after molding it from resin. However, if glass fibers are woven into the resin that forms the sheet 4, the glass fibers will be exposed on the surface of the sheet 4 due to processing, which may reduce the abrasion resistance.

[0027] In contrast to this, in this embodiment, in the manufacturing method of the EGR valve device 1, the following technique is used to improve the sealing performance between the seat 4 and the valve 5 when the valve is fully closed.

[0028] (First Example) First, a first embodiment will be described. In this embodiment, the sheet 4 is made of resin (for example, PPS (polyphenylene sulfide)), and the valve 5 is made of metal (for example, stainless steel). The housing 3 is made of metal (for example, aluminum (ADC12, etc.)) or resin (for example, PPS (polyphenylene sulfide)). When the housing 3 is made of resin, the sheet 4 may be formed integrally with the housing 3.

[0029] Therefore, in this embodiment, in the manufacturing method of the EGR valve device 1, the valve 5 and the shaft 6 are welded together and the valve 5 is pressed as follows, thereby improving the sealing performance between the seat 4 and the valve 5 when the valve is fully closed.

[0030] First, the seat 4 is placed in a predetermined position in the housing 3, and the shaft 6 is set in a state in which the shaft 6 is connected to the drive unit 7. At this time, as shown in FIG. 2, the shaft 6 is set so that it is inserted into the seat hole 4a on the inside of the seat 4.

[0031] Next, the valve 5 is set by inserting the shaft 6 into the hole 5a inside the valve 5 and bringing the valve 5 into contact with the seat 4, as shown in FIG.

[0032] Next, a welding jig, 11, is set in place. At this time, as shown in Fig. 4, the earthing jig 11 is set so as to be disposed on the surface 5b of the valve 5 opposite the seat 4. As a result, the valve 5 is sandwiched between the seat 4 and the earthing jig 11 and fixed (clamped).

[0033] Next, the valve 5 and the shaft 6 are welded together, and the valve 5 is pressed. At this time, as shown in FIG. 5 , a welding electrode 12 is used to weld the valve 5 and the shaft 6 together, and an earth jig 11 is used to press the valve 5 against the seat 4. In this way, the valve 5 is heated by welding, and the heated valve 5 is pressed against the seat 4. As a result, the valve 5 is brought into contact with the annular seat 4 over its entire circumferential direction when fully closed.

[0034] As described above, in this embodiment, the manufacturing method of the EGR valve device 1 includes a step of heating the valve 5 (an example of the "valve body heating step" of the present disclosure) and a step of pressing the heated valve 5 against the seat 4 (an example of the "heated valve body pressing step" of the present disclosure). The step of heating the valve 5 also serves as a step of welding the valve 5 and the shaft 6 (an example of the "welding step" of the present disclosure).

[0035] More specifically, in this embodiment, first, in the step of welding the valve 5 and the shaft 6, the valve 5 is pressed against the sheet 4 with a low pressure (the pressure value at this time is, for example, 20 N), and then the valve 5 is abutted against the sheet 4 to stabilize the position of the valve 5, and the valve 5 and the shaft 6 are welded together. Then, simultaneously with or after this, in the step of pressing the heated valve 5 against the sheet 4, the valve 5 is pressed against the sheet 4 with an even higher pressure (the pressure value at this time is, for example, 100 N (five times the pressure value in the welding step)).

[0036] In this way, by pressing the heated valve 5 against the sheet 4 while utilizing the heat generated when welding the valve 5 to the shaft 6, the shape of the resin sheet 4 can be made to conform to the shape of the valve 5. As an example, if the sheet 4 is made of PPS (melting point: approximately 280°C), the temperature of the heated valve 5 is set to, for example, 200°C.

[0037] Further, referring to the drawings, before the shape of the seat 4 conforms to the shape of the valve 5, as shown in FIGS. 6 and 7, the seat 4 and the valve 5 are in contact with each other in region A1 in the circumferential direction of the seat 4, but are not in contact with each other in region A2, leaving a gap δ between the seat 4 and the valve 5.

[0038] However, after the shape of the seat 4 has adapted to the shape of the valve 5, as shown in Figures 8 and 9, a portion D of the seat 4 is displaced in the circumferential direction as it adapts to the shape of the valve 5, and the shape of the seat 4 adapts to the shape of the valve 5 over the entire area A, bringing the seat 4 and the valve 5 into contact. This reduces the gap between the valve 5 and the seat 4 over the entire circumference when the valve is fully closed, improving the sealing performance between the seat 4 and the valve 5.

[0039] Furthermore, the process of welding the valve 5 and the shaft 6 also serves as a process of heating the valve 5, eliminating the need for a separate process of heating the valve 5 in addition to the process of welding the valve 5 and the shaft 6. Therefore, in the manufacturing method of the EGR valve device 1, the shape of the seat 4 can be efficiently adapted to the shape of the valve 5, thereby improving the sealing performance between the seat 4 and the valve 5 when the valve is fully closed.

[0040] It should be noted that the process of welding the valve 5 and the shaft 6 does not necessarily have to be used as the process of heating the valve 5. As a variant, the valve 5 may be heated by a heat source such as a heater (not shown), and the valve 5 thus heated by the heater may be pressed against the sheet 4.

[0041] (Second Example) Next, a second embodiment will be described, focusing on the differences from the first embodiment, and omitting a description of the commonalities with the first embodiment.

[0042] In this embodiment, the manufacturing method of the EGR valve device 1 includes a step of heating the seat 4 (an example of the "valve seat heating step" of the present disclosure) and a step of pressing the valve 5 against the heated seat 4 (an example of the "valve body pressing step" of the present disclosure). By performing the step of pressing the valve 5 against the heated seat 4, the valve 5 is brought into contact with the annular seat 4 over the entire circumferential direction when fully closed.

[0043] In this way, the sheet 4 is heated by a heat source such as a heater instead of the valve 5, and the valve 5 is pressed against the heated sheet 4. As an example, if the sheet 4 is made of PPS (melting point: approximately 280°C), the temperature of the heated sheet 4 is set to, for example, 200°C.

[0044] This allows the shape of the resin sheet 4 to conform to the shape of the valve 5. Therefore, when the valve is fully closed, the gap between the sheet 4 and the valve 5 can be reduced over the entire circumference, improving the sealing performance between the sheet 4 and the valve 5.

[0045] Furthermore, since there is no need to heat the bulb 5, the bulb 5 can be made of a material other than metal (for example, resin).

[0046] It should be noted that the above-described embodiments are merely examples and do not limit the present disclosure in any way. It goes without saying that various improvements and modifications are possible within the scope of the gist of the present disclosure.

[0047] The above-described embodiment can be applied to valve devices other than the EGR valve device 1. [Explanation of symbols]

[0048] 1 EGR valve device 2 Flow path 3. Housing 4 seats 5 valves 6 shafts 7 Drive unit

Claims

1. A method for manufacturing a valve device having a resin valve seat and a metal valve body that abuts against and separates from the valve seat, comprising: a valve body heating step of heating the valve body; a heated valve element pressing step of pressing the valve element heated in the valve element heating step against the valve seat; and the valve device has a valve stem to which the valve body is welded, the valve body heating step is a welding step of welding the valve body and the valve stem, sandwiching and fixing the valve body between the valve seat and a welding jig, and then welding the valve body and the valve stem together using a welding electrode, and pressing the valve body toward the valve seat with the welding jig; A method for manufacturing a valve device, comprising:

2. The method for manufacturing a valve device according to claim 1, the heating valve element pressing step causes the valve element to abut against the annular valve seat over the entire circumferential direction thereof when the valve seat and the valve element abut against each other at a fully closed state; A method for manufacturing a valve device, comprising:

Images