JP2024078859A - Resin valve device and its manufacturing method - Google Patents

Abstract

To suppress dimensional change of a housing due to temperature difference or temperature change of a use environment, to suppress change in valve opening characteristic, in a resin valve device.SOLUTION: A resin valve device comprises: a housing 3 including a flow path 2, and formed into a cylindrical manner from a fiber-reinforced resin; a valve seat provided in the flow path 2; a valve body provided in the flow path 2 so as to be able to seat on the valve seat; a valve shaft on which the valve body is provided; and a drive part that drives the valve shaft. The resin housing 3 has a plurality of ribs 3e, 3f extending in an axial direction on its outer peripheral surface and protruding in a radial direction, and a gate mark 11 formed by injection molding of a molten resin is arranged on an end surface 3Aa of one end side 3A of the housing 3 in the axial direction X.SELECTED DRAWING: Figure 2

Description

The technology disclosed in this specification relates to a resin valve device whose housing is made of resin and a method for manufacturing the same.

A conventional example of this type of technology is the EGR valve described in Patent Document 1 below. This EGR valve is provided in the EGR gas passage and is used to adjust the EGR gas flow rate. This valve includes a housing including a flow path for EGR gas, a valve seat provided in the flow path, a valve body provided in the flow path so that it can be seated on the valve seat, a valve stem provided with the valve body, and a drive unit for driving the valve stem, and the housing is manufactured from a resin material.

JP 2021-71102 A

However, when the housing is made of resin, the dimensions of the housing change due to the difference in linear expansion between normal and high temperatures, which can cause the opening characteristics of the EGR valve to change significantly. For example, when the EGR valve is opened at normal temperatures and when it is opened at high temperatures, there is a difference in the amount of drive of the drive unit for the same opening. In other words, the opening characteristics of the EGR valve change. In addition, because the housing is made of resin, it is difficult to ensure the roundness of the valve seat if the valve seat is resin-molded integrally with the housing.

This disclosed technology was made in consideration of the above circumstances, and its purpose is to provide a resin valve device and a manufacturing method thereof that can suppress dimensional changes in the housing due to temperature differences or temperature changes in the usage environment and suppress changes in the valve opening characteristics.

In order to achieve the above object, the technology described in claim 1 is directed to a resin valve device including a housing that includes a flow path and is formed into a cylindrical shape from fiber-reinforced resin, the flow path including an inlet and an outlet, a valve seat provided in the flow path, a valve body provided in the flow path so that it can be seated on the valve seat, a valve shaft on which the valve body is provided, and a drive unit for driving the valve shaft, in which the housing has a plurality of ribs that extend in the axial direction and protrude in the radial direction on its outer circumferential surface, and a gate mark formed by injection molding of molten resin is disposed on an end surface on one end side of the housing in the axial direction.

According to the configuration of the above technology, the housing has multiple ribs that extend axially and protrude radially on its outer peripheral surface, so that the housing is structurally reinforced by the ribs. In addition, a gate mark is located on the end face of one end of the housing in the axial direction, so that when the housing is injection molded, fiber-reinforced molten resin is injected into the cavity of the mold from the gate at one end in the axial direction. This makes it easier for the orientation of the fibers in the molten resin to be aligned in the axial direction of the housing. In addition, because the ribs extend in the axial direction of the housing, the fiber-reinforced molten resin flows more easily in that direction, making it easier for the orientation of the fibers to be aligned.

To achieve the above object, the technology described in claim 2 aims to provide a resin valve device as described in claim 1, in which the valve seat is formed integrally with the housing at one end where the gate mark is located.

According to the configuration of the above technology, in addition to the effect of the technology described in claim 1, the valve seat is integrally formed with the housing at one end where the gate mark is located, so that the fiber-reinforced molten resin injected from the gate is easily filled in the position corresponding to the valve seat.

To achieve the above object, the technology described in claim 3 aims to position the gate marks in the resin valve device described in claim 1 so as to correspond to the spaces between adjacent ribs in the circumferential direction of the end face on one end side of the housing.

According to the configuration of the above technology, in addition to the effect of the technology described in claim 1, the gate marks are arranged in the circumferential direction of the end face on one end side of the housing, corresponding to the spaces between adjacent ribs, so that the fiber-reinforced molten resin injected from the gate first flows in the circumferential direction of the cavity and then flows in the axial direction.

In order to achieve the above object, the technology described in claim 4 is a manufacturing method for manufacturing a resin valve device described in any one of claims 1 to 3, in which the housing is molded in a cavity of a mold from fiber-reinforced molten resin injected from a gate that is positioned corresponding to an end face on one end side of the housing.

According to the configuration of the above technology, the housing is molded from fiber-reinforced molten resin that is injected into the cavity of the mold from a gate that is positioned corresponding to the end face of one end of the housing. Therefore, the orientation of the fibers in the molten resin is easily aligned in the axial direction of the housing. In addition, because the ribs extend in the axial direction of the housing, the fiber-reinforced molten resin easily flows in that direction, making it easier to align the orientation of the fibers.

The technology described in claim 1 can suppress dimensional changes in the housing due to temperature differences or temperature changes in the usage environment, and suppress changes in the opening characteristics of the valve device.

The technology described in claim 2 can improve the roundness of the valve seat in addition to the effect of the technology described in claim 1.

According to the technology described in claim 3, in addition to the effect of the technology described in claim 1, the valve seat and the area where the valve seat is located can be sufficiently filled with molten resin, and the roundness of the valve seat and the area where the valve seat is located and the fiber orientation in the rib can be further improved.

The technology described in claim 4 makes it possible to manufacture a housing that undergoes minimal dimensional change due to temperature differences or temperature changes in the usage environment. This housing contributes to suppressing changes in the opening characteristics of the valve device.

FIG. 2 is a cross-sectional view showing an EGR valve in the first embodiment. FIG. 4 is a perspective view showing a state in which an outlet of a flow path of the housing faces the front in the first embodiment. FIG. 4 is a perspective view showing a state in which an outlet of a flow path of the housing faces rearward in the first embodiment. 5A to 5C are cross-sectional views each illustrating a part of a housing manufacturing process using a mold in the first embodiment. 5 is a pie chart showing the circularity of the valve seat after resin molding shrinkage in the first embodiment. FIG. 9 is a perspective view equivalent to FIG. 3 showing a housing in a second embodiment. 13 is a pie chart showing the circularity of the valve seat after resin molding shrinkage in the second embodiment.

Below, several embodiments of the resin valve device and its manufacturing method applied to an EGR valve will be described in detail with reference to the drawings.

First Embodiment
First, the first embodiment will be described in detail with reference to FIGS.

[EGR valve configuration]
Fig. 1 shows a cross-sectional view of an EGR valve 1 according to this embodiment. As shown in Fig. 1, the EGR valve 1 has a poppet-type valve structure, and includes a housing 3 including a flow passage 2 for EGR gas, an annular valve seat 4 provided in the flow passage 2, a substantially umbrella-shaped valve element 5 provided in the flow passage 2 so as to be able to seat on the valve seat 4, a valve shaft 6 to which the valve element 5 is fixed at one end, and a drive unit 7 for driving the valve shaft 6 together with the valve element 5 to reciprocate in the axial direction. The housing 3 is fastened to the drive unit 7 by thermal caulking (not shown). The valve shaft 6 extending from the drive unit 7 is fitted into a central hole 8 of the housing 3.

The flow passage 2 includes an inlet 2a at one end and an outlet 2b at the other end. The drive unit 7 can be configured, for example, by a well-known DC motor or step motor. The housing 3 is formed in a substantially cylindrical shape from fiber-reinforced resin. The valve seat 4 is formed from resin integrally with the housing 3. The valve body 5 and the valve shaft 6 are formed from a metal material. The EGR valve 1 adjusts the EGR gas flow rate in the flow passage 2 by moving the valve body 5 axially relative to the valve seat 4 to change the opening between the valve seat 4. A detailed description of the drive unit 7 will be omitted here.

[Housing configuration]
The configuration of the housing 3 will be described. Figures 2 and 3 show the housing 3 of this embodiment in a perspective view in a state in which the housing 3 shown in Figure 1 is turned upside down. Figure 2 shows a state in which the outlet 2b of the flow path 2 faces forward, and Figure 3 shows a state in which the outlet 2b faces backward. In Figures 2 and 3, the inlet 2a of the flow path 2 can be seen at the upper end of the housing 3. In this embodiment, the side of the housing 3 where the inlet 2a is located is defined as one end side 3A of the housing 3, and the side opposite the one end side 3A is defined as the other end side 3B.

In this embodiment, the housing 3 is substantially cylindrical, and externally has a one-end flange 3a located at the upper end in FIG. 2 and FIG. 3, a second-end flange 3b located at the lower end, and two-stage intermediate flanges 3c, 3d located in the middle. The housing 3 has a plurality of ribs 3e, 3f extending in the axial direction and protruding in the radial direction on its outer circumferential surface. That is, between the one-end flange 3a and the intermediate flange 3c, three one-end ribs 3e extending in the axial direction are provided. The one-end ribs 3e are provided at equal angular intervals (90°) at positions that do not interfere with the outlet 2b of the flow path 2. In addition, between the other-end flange 3b and the intermediate flange 3d, four other-end ribs 3f extending in the axial direction are provided at equal angular intervals (90°). The arrangement of the one-end ribs 3e and the other-end ribs 3f coincides in the circumferential direction. The dashed lines indicated by crosses in FIG. 2 and FIG. 3 coincide with the arrangement direction of each rib 3e, 3f.

In this embodiment, as shown in Figures 2 and 3, multiple (four) gate marks 11 are arranged on the end face 3Aa of one end side 3A of the housing 3 in the axial direction X by injection molding of fiber-reinforced molten resin. In this embodiment, the valve seat 4 is arranged on the one end side 3A of the housing 3 where the four gate marks 11 are arranged. That is, the valve seat 4 is formed integrally with the housing 3 on the one end side 3A where the four gate marks 11 are arranged. The four gate marks 11 are arranged in the circumferential direction of the end face 3Aa of the one end side 3A of the housing 3, corresponding to between adjacent one end side ribs 3e and one end side ribs 3e.

[About the manufacturing method of EGR valve]
The EGR valve 1 of this embodiment can be manufactured by separately manufacturing the drive unit 7 to which the valve stem 6 is attached, the valve body 5, and the housing 3, fastening the drive unit 7 and the housing 3 to each other, and fixing the valve body 5 to the tip of the valve stem 6 at the inlet 2a of the housing 3.

Here, the housing 3 is manufactured by injection molding a resin material as follows. FIG. 4 is a schematic cross-sectional view showing part of the housing manufacturing process using a mold 21. This mold 21 is configured to be clamped and opened in the front-rear direction of FIG. 4. As shown in FIG. 4, the mold 21 is used to injection mold the housing 3 with resin. As shown in FIG. 4, a cavity 23 for molding the housing 3 is formed in the clamped mold 21. Cores 24, 25, and 26 for molding the flow path 2 and the central hole 8 are placed in this cavity 23. Each of the cores 24 to 26 is configured to be removed from the mold 21 in the direction of the arrow.

In FIG. 4, the upper side of the cavity 23 corresponds to one end side 3A of the housing 3, and the lower side corresponds to the other end side 3B. In correspondence with the upper side of the cavity 23, the mold 21 is provided with a plurality of gates 27 for injecting molten resin into the cavity 23. In FIG. 4, two gates 27 are shown, but a total of four gates 27 are provided. These gates 27 are arranged in correspondence with one end side of the cavity 23, i.e., the end face of the one end flange 3a of the housing 3. The housing 3 is then molded in the cavity 23 of the mold 21 with molten resin containing fibers injected from the four gates 27 arranged in correspondence with the end face 3Aa of the one end side 3A of the housing 3.

[About the action and effect of the EGR valve and its manufacturing method]
According to the configuration of the EGR valve 1 of this embodiment described above, the housing 3 has a plurality of ribs 3e, 3f extending in the axial direction and projecting in the radial direction on its outer circumferential surface, so that the housing 3 is structurally reinforced by the ribs 3e, 3f. In addition, since a plurality of gate marks 11 are arranged on the end face 3Aa of the one end side 3A in the axial direction of the housing 3, the fiber-containing molten resin is injected from the gate 27 at the one end side in the axial direction into the cavity 23 of the mold 21 during injection molding of the housing 3. Therefore, the orientation of the fibers in the molten resin is easily aligned in the axial direction X of the housing 3. In addition, since the plurality of ribs 3e, 3f extend in the axial direction X of the housing 3, the fiber-containing molten resin easily flows in that direction, so that the orientation of the fibers is easily aligned. Therefore, it is possible to suppress the dimensional change of the housing 3 due to the temperature difference or temperature change in the usage environment, and it is possible to suppress the change in the valve opening characteristic of the EGR valve 1.

In this embodiment, the fiber orientation rate of the plastic housing 3 was improved to 54%. This is an improvement over the fiber orientation rate of 41% when the gate marks are located on the side of the housing instead of the end face. When the housing's operating environment changes from 20°C to 130°C, the axial extension of the housing due to the temperature difference is 0.02 mm greater when the orientation rate is 41% than when it is 54%. This corresponds to 0.4 steps when converted into the number of opening steps of an EGR valve with a step motor as the drive unit.

The above-mentioned "orientation rate" is defined as the orientation tensor direction, which is an orientation tensor direction for each of the countless points set in the model in which the analysis was performed. The orientation tensor direction is "1" when the XYZ components of a certain point are added together. In the above explanation, the average value of the Z components (flow direction) of all points is defined as the "orientation rate".

According to the configuration of the EGR valve 1 of this embodiment, the valve seat 4 is formed integrally with the housing 3 at one end side 3A where the multiple gate marks 11 are arranged. Therefore, when the housing 3 is manufactured, the fiber-reinforced molten resin injected from the gate 27 into the cavity 23 in the mold 21 is more likely to fill the position corresponding to the valve seat 4 with high-temperature molten resin. This makes it possible to improve the roundness of the valve seat 4.

According to the configuration of the EGR valve 1 of this embodiment, multiple gate marks 11 are arranged in the circumferential direction of the end face 3Aa of the one end side 3A of the housing 3, corresponding to the positions between adjacent one end side ribs 3e and one end side ribs 3e. Therefore, when the housing 3 is manufactured, the fiber-reinforced molten resin injected from the multiple gates 27 flows first in the circumferential direction of the cavity 23 and then in the axial direction, as shown by the arrows in FIG. 3. This allows the valve seat 4 and the area where the valve seat 4 is located to be sufficiently filled with molten resin, further improving the roundness of the valve seat 4 and the area where the valve seat 4 is located, and the fiber orientation in each of the ribs 3e, 3f.

Figure 5 shows a pie chart of the circularity of the valve seat 4 after resin molding shrinkage in this embodiment. As shown in Figure 5, the degree of shrinkage in this embodiment varies in the range of "13.15 to 13.165", but it can be seen that it is within a relatively narrow range.

According to the configuration of the manufacturing method of the EGR valve 1 of this embodiment, the housing 3 is molded in the cavity 23 of the mold 21 with fiber-reinforced molten resin injected from multiple gates 27 arranged corresponding to the end face 3Aa of one end side 3A of the housing 3. Therefore, the orientation of the fibers in the molten resin in the axial direction X of the housing 3 is easily aligned. In addition, since the multiple ribs 3e, 3f extend in the axial direction X of the housing 3, the fiber-reinforced molten resin flows easily in that direction, and the orientation of the fibers is easily aligned. Therefore, it is possible to manufacture a housing 3 with little dimensional change due to temperature differences or temperature changes in the usage environment. This housing 3 contributes to suppressing changes in the opening characteristics of the EGR valve 1.

Second Embodiment
Next, the second embodiment will be described in detail with reference to Figures 6 and 7. In the following description, the same components as those in the first embodiment will be denoted by the same reference numerals and the description will be omitted, and the differences will be mainly described.

[EGR valve configuration]
This embodiment differs from the first embodiment in the configuration of the housing 3, i.e., in the arrangement of the multiple gate marks 11 on the end face 3Aa of one end side 3A of the housing 3. Figure 6 shows the housing 3 of this embodiment in a perspective view similar to Figure 3. In this embodiment, the multiple gate marks 11 are arranged in the circumferential direction of the end face 3Aa of one end side 3A of the housing 3 so as to coincide with the one-end rib 3e.

[About the action and effect of the EGR valve and its manufacturing method]
According to the configuration of the EGR valve 1 of this embodiment described above, the multiple gate marks 11 are arranged to coincide with the one-end ribs 3e in the circumferential direction of the end face 3Aa of the one end side 3A of the housing 3. Therefore, when the housing 3 is manufactured, the fiber-reinforced molten resin injected from the multiple gates 27 in the mold 21 is more likely to flow in the axial direction of the cavity 23 than in the circumferential direction, as shown by the arrows in Fig. 6. In this regard, although the effect of the roundness of the valve seat 4 is somewhat reduced, the same actions and effects as those of the first embodiment can be obtained.

Figure 7 shows the circularity of the valve seat 4 after resin molding shrinkage in this embodiment in a pie chart. As shown in Figure 7, the degree of shrinkage in this embodiment varies in the range of "13.155 to 13.175", and it can be seen that the circularity is lower than in the first embodiment.

<Another embodiment>
The disclosed technology is not limited to the above-described embodiments, and may be implemented by modifying part of the configuration as appropriate without departing from the spirit of the disclosed technology.

(1) In each of the above embodiments, four gate marks 11 are provided on the housing 3, but it is also possible to provide less than four or more than four gate marks.

(2) In each of the above embodiments, multiple gate marks 11 are provided on the end face 3Aa of the one end side 3A of the housing 3 that is close to the valve seat 4, but gate marks may also be provided on the end face of the other end side 3B opposite the one end side 3A of the housing 3 that is close to the valve seat 4.

(3) In each of the above embodiments, the valve seat 4 is formed integrally with the housing 3, but the valve seat and the housing may be assembled separately.

(4) In each of the above embodiments, the resin valve device is embodied in the EGR valve 1, but is not limited to EGR valves.

This disclosed technology can be used in valve devices such as EGR valves.

1 EGR valve (plastic valve device)
Reference Signs 2: Flow Channel 2a: Inlet 2b: Outlet 3: Housing 3e: One End Rib 3f: Other End Rib 3A: One End 3Aa: End Face 3B: Other End 4: Valve Seat 5: Valve Body 6: Valve Shaft 7: Drive Part 11: Gate Trace 21: Mold 23: Cavity 27: Gate X: Axial Direction

Claims (4)

a housing including a flow path and formed into a cylindrical shape from a fiber-reinforced resin;
the flow path includes an inlet and an outlet;
A valve seat provided in the flow path;
a valve body provided in the flow path so as to be able to seat on the valve seat;
a valve shaft provided with the valve body;
and a drive unit for driving the valve shaft.
The housing has a plurality of ribs extending in an axial direction and projecting in a radial direction on an outer circumferential surface thereof,
A resin valve device, characterized in that a gate mark formed by injection molding of molten resin is disposed on an end surface on one end side in the axial direction of the housing. The resin valve device according to claim 1,
The resin valve device is characterized in that the valve seat is formed integrally with the housing at the one end side where the gate mark is located. The resin valve device according to claim 1,
The resin valve device is characterized in that the gate marks are arranged corresponding to spaces between adjacent ribs in the circumferential direction of the end face on the one end side of the housing. A method for manufacturing the resin valve device according to any one of claims 1 to 3,
A manufacturing method for a resin valve device, characterized in that the housing is molded in a cavity of a mold from fiber-reinforced molten resin injected from a gate that is positioned corresponding to the end face of the one end of the housing.

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