JP6207994B2 - Poppet valve and valve assembly - Google Patents

Description

  The present invention relates to, for example, a poppet valve used for adjusting the flow rate of exhaust gas flowing through an EGR (Exhaust Gas Recirculation) passage, and a valve assembly.

  The valve assembly includes a poppet valve and a valve seat. The poppet valve can reciprocate in a linear direction. In the fully closed state where the passage is completely closed, the poppet valve is seated on the valve seat. On the other hand, the poppet valve is separated from the valve seat in the fully open state where the passage is completely opened. When the valve is closed (when the passage is switched from the open state to the fully closed state), the poppet valve contacts the valve seat. Poppet valves and valve seats are worn by the impact at the time of contact.

  In this regard, Patent Document 1 discloses a poppet valve including a seal member (valve element) with a protruding portion. The seal member is mounted on the valve shaft. A projecting portion having flexibility is formed on a portion of the seal member that contacts the valve seat. When the poppet valve comes into contact with the valve seat, the protrusion is bent. For this reason, the impact by contact | abutting can be absorbed.

JP-A-9-264431

  However, according to the poppet valve described in the document, the projecting portion is formed in an annular shape near the outer edge of the seal member. On the other hand, a mounting portion for the valve shaft is disposed near the center in the radial direction of the seal member. For this reason, when the protrusion comes into contact with the valve seat when the valve is closed, stress is concentrated on the mounting portion. SUMMARY OF THE INVENTION An object of the present invention is to provide a poppet valve and a valve assembly in which stress is less likely to concentrate on a mounting portion of a valve body with respect to a valve shaft.

(1) In order to solve the above-described problem, a poppet valve of the present invention has a valve shaft and a valve body that has a mounting portion attached to the valve shaft and can be seated and separated from the valve seat. The valve body has a contact portion that contacts the valve seat, and an umbrella portion interposed between the contact portion and the attachment portion, and the thickness of the valve body The thinnest thin portion is disposed at the boundary between the corresponding contact portion and the umbrella portion, and the umbrella portion gradually increases in thickness from the thin portion toward the boundary with the attachment portion. To do.

  The valve shaft and the valve body of the poppet valve of the present invention are separate bodies. When the valve is closed (when the passage is switched from the open state to the fully closed state), the valve element comes into contact with the valve seat. Due to the impact at the time of contact, stress tends to concentrate on the mounting portion of the valve body. In this regard, a thin portion is disposed in the valve body of the poppet valve of the present invention. The thin portion is disposed in a portion other than the attachment portion of the valve body. Compared with the attachment part, the thin part is easily elastically deformed. For this reason, the stress concentration on the mounting portion when the valve is closed can be reduced. Further, when the thin portion is elastically deformed when the valve is closed, at least a part of the impact when seated on the valve seat can be absorbed. Moreover, according to the poppet valve of this invention, it is easy to ensure the contact area between a valve body and a valve seat. For this reason, the sealing performance in the fully closed state is high.

( 2 ) In the configuration of (1 ) , the valve body is preferably configured to be elastically deformed by an impact when the valve body is seated on the valve seat. According to this structure, at least a part of the impact when the valve body is seated on the valve seat can be absorbed by the elastic deformation of the valve body.

( 3 ) In order to solve the above-mentioned problems, a valve assembly according to the present invention includes the poppet valve according to (1) or ( 2) . According to the valve assembly of the present invention, similarly to the above (1), the stress concentration on the mounting portion when the valve is closed can be reduced. Further, when the thin portion is elastically deformed when the valve is closed, at least a part of the impact when seated on the valve seat can be absorbed. Moreover, the sealing performance in the fully closed state is high.

  According to the present invention, it is possible to provide a poppet valve and a valve assembly in which stress is less likely to concentrate on a mounting portion of the valve body with respect to the valve shaft.

It is an axial sectional view in the fully opened state of the valve assembly which is one embodiment of the valve assembly of the present invention. It is an axial sectional view in the fully closed state of the valve assembly. It is an enlarged view in the frame III of FIG. It is an axial sectional view of a part of a valve element of a poppet valve of another embodiment (part 1). It is an axial sectional view of a part of a valve body of a poppet valve of another embodiment (part 2).

  Hereinafter, an embodiment in which the valve assembly of the present invention is embodied as a valve assembly for EGR will be described.

<Configuration of valve assembly>
First, the configuration of the valve assembly of this embodiment will be described. FIG. 1 shows an axial sectional view of the valve assembly of the present embodiment in a fully opened state. FIG. 2 shows an axial sectional view of the valve assembly in a fully closed state. FIG. 3 shows an enlarged view in the frame III of FIG.

  As shown in FIGS. 1 to 3, the valve assembly 1 of this embodiment includes a housing 2, a poppet valve 3, an axial bearing 51, a coil spring 52, a motor 53, and a valve seat 54. Yes.

  The housing 2 is formed with an EGR passage 20, a recess 21, and a valve shaft insertion hole 22. The EGR passage 20 extends in an L shape. The exhaust gas flows through the EGR passage 20 from the lower side (upstream side) toward the right side (downstream side). The recess 21 is recessed on the upper surface of the housing 2. A spring seat 21 a is disposed on the bottom surface of the recess 21. The valve shaft insertion hole 22 communicates the EGR passage 20 and the recess 21 in the vertical direction.

  The valve seat 54 has an annular shape. The valve seat 54 is disposed near the lower end opening (upstream end opening) of the EGR passage 20. The axial bearing 51 is disposed on the inner peripheral surface of the valve shaft insertion hole 22. The motor 53 covers the recess 21 from above. The motor 53 can reciprocate the motor side shaft 530 in the vertical direction.

  The poppet valve 3 includes a valve body 30 and a valve shaft 31. The valve shaft 31 includes a shaft main body 310 and a flange portion 311. The shaft main body 310 is made of stainless steel and has a round bar shape extending in the vertical direction (axial direction). The shaft main body 310 is inserted inside the axial bearing 51 in the radial direction. A step portion 310 a is formed near the lower end portion of the shaft main body 310. In the stepped portion 310a, the outer diameter of the shaft main body 310 increases from the upper side to the lower side. On the other hand, the upper end of the shaft main body 310 is in contact with the motor side shaft 530. The flange portion 311 has a cup shape opening upward. The flange portion 311 is disposed at the upper end of the shaft main body 310. A spring seat 311 a is disposed on the outer peripheral edge of the flange portion 311.

  The valve body 30 is made of stainless steel and has a disk shape. The valve body 30 is produced by press-molding a stainless steel plate material. As shown in FIG. 3, the valve body 30 includes an attachment portion 300, a contact portion 301, an umbrella portion 302, and a thin portion A. The attachment portion 300 has a cylindrical shape extending in the vertical direction (axial direction). The attachment portion 300 is mounted around the lower end portion of the shaft main body 310 of the valve shaft 31. The attachment portion 300 is locked from above with respect to the step portion 310a. For this reason, the attachment portion 300, that is, the valve body 30 does not fall down from the shaft body 310, that is, the valve shaft 31. The umbrella portion 302 has a disk shape extending in the horizontal direction (radial direction). The umbrella portion 302 projects radially outward from the upper end of the attachment portion 300. The contact portion 301 has a tapered cylindrical shape that is pointed from the lower side toward the upper side. The contact portion 301 extends obliquely downward from the outer edge of the umbrella portion 302. As shown in FIG. 2, the contact portion 301 can be seated and separated from the lower side with respect to the valve seat 54. As shown in FIG. 3, round chamfered curved portions R <b> 1 and R <b> 2 are arranged at the boundary between the attachment portion 300 and the umbrella portion 302 and at the boundary between the umbrella portion 302 and the contact portion 301.

  As shown in FIG. 3, the thin-walled portion A is disposed at the boundary (that is, the curved portion R <b> 2) between the upper end of the contact portion 301 and the outer edge of the umbrella portion 302. The thin portion A is recessed on the lower surface (upstream surface) of the valve body 30. That is, the annular groove B is recessed on the lower surface of the curved portion R2. The thin portion A is formed by reducing the thickness of the curved portion R2 by the amount of the groove B. In addition, what is shown by a dotted line in FIG. 3 is a state in which the thin portion A is not provided. In the valve body 30 as a whole, the thickness of the thin portion A is the thinnest. That is, the thickness T1 of the thin portion A (the distance between the upper surface (downstream surface) and the lower surface (upstream surface) of the curved portion R2 and the distance in the curvature radius direction of the upper surface of the curved portion R2). Is thinner than the wall thickness T2 of the mounting portion 300. In addition, the thickness T1 of the thin portion A is thinner than the thickness T3 of the contact portion 301. Further, the thickness T1 of the thin portion A is thinner than the thickness T4 of the umbrella portion 302. For this reason, compared with the attachment part 300, the contact part 301, and the umbrella part 302, the thin part A has low rigidity and is easily elastically deformed (easy to bend).

  As shown in FIGS. 1 and 2, the coil spring 52 is disposed between the spring seat 311a and the spring seat 21a. The coil spring 52 urges the poppet valve 3 upward with respect to the housing 2.

<Valve assembly movement>
Next, the movement of the valve assembly of this embodiment will be briefly described. When switching from the fully closed state shown in FIG. 2 to the fully open state shown in FIG. 1, the motor 53 is driven to lower the valve shaft 31 against the urging force of the coil spring 52. The contact portion 301 of the valve body 30 is separated from the valve seat 54. On the other hand, when switching from the fully open state shown in FIG. 1 to the fully closed state shown in FIG. 2, the motor 53 is stopped and the valve shaft 31 is raised by the urging force F <b> 1 of the coil spring 52. The contact portion 301 of the valve body 30 is seated on the valve seat 54. In the fully closed state, the urging force F <b> 1 of the coil spring 52 acts upward on the valve body 30. In the fully closed state, the exhaust gas pressure F <b> 2 acts upward on the valve body 30.

<Effect>
Next, the function and effect of the valve assembly of this embodiment will be described. As exaggeratedly shown by a one-dot chain line in FIG. 2, when the valve is closed (when the EGR passage 20 is switched from the open state to the fully closed state shown in FIG. 2), the contact portion 301 is placed on the valve seat 54. Sit from below. In addition, the attachment portion 300 is pulled upward by the valve shaft 31 in a state where the contact portion 301 is locked to the valve seat 54. For this reason, the valve body 30 is elastically deformed in a conical shape as a whole. Due to the impact when the contact portion 301 contacts the valve seat 54, stress tends to concentrate on the mounting portion 300.

  In this regard, the thin portion A is disposed on the valve body 30 of the poppet valve 3 of the present embodiment as shown in FIG. The thin portion A is disposed at the boundary between the contact portion 301 and the umbrella portion 302 (that is, the curved portion R2). That is, the thin portion A is disposed in a portion other than the attachment portion 300 in the valve body 30. Compared with the attachment part 300, the thin part A is easily elastically deformed. For this reason, the stress concentration to the attachment part 300 at the time of valve closing can be relieved. Therefore, the maximum stress generated in the attachment portion 300, that is, the allowable stress of the attachment portion 300 can be reduced. Further, when the thin portion A is elastically deformed when the valve is closed, at least a part of the impact when seated on the valve seat 54 can be absorbed.

  Moreover, in the case of the poppet valve of patent document 1, it is necessary to form the protrusion part for shock absorption in a sealing member (valve body). For this reason, there exists a possibility that the sealing performance in a fully closed state may fall. That is, in the fully closed state, the sealing performance is ensured by the contact between the seal member and the valve seat. When the protrusion is formed on the seal member, the contact area between the seal member and the valve seat is reduced. For this reason, there exists a possibility that sealing performance may fall. On the other hand, according to the poppet valve 3 of the present embodiment, it is not necessary to form a protruding portion in the contact portion 301 of the valve body 30. For this reason, the contact area between the contact part 301 and the valve seat 54 can be enlarged. Therefore, high sealing performance can be ensured in the fully closed state.

  Further, according to the poppet valve 3 of the present embodiment, as shown in FIG. In other words, the thin portion A is disposed at the base portion of the contact portion 301. For this reason, when the valve is closed, the contact portion 301 is easily elastically deformed starting from the thin portion A. Therefore, the contact portion 301 is easily deformed following the shape of the valve seat 54. Therefore, the adhesion between the contact portion 301 and the valve seat 54 in the fully closed state can be improved. Further, the thickness T3 of the contact portion 301 is as thin as 1.5 mm or less. Also in this point, the contact portion 301 is easily deformed following the shape of the valve seat 54. Therefore, the adhesion between the contact portion 301 and the valve seat 54 in the fully closed state can be improved. Further, as shown by a one-dot chain line in FIG. 2, the valve body 30 is elastically deformed by an impact at the time of sitting. For this reason, at least a part of the impact at the time of sitting can be absorbed.

<Others>
The embodiments of the poppet valve and the valve assembly of the present invention have been described above. However, the embodiment is not particularly limited to the above embodiment. Various modifications and improvements that can be made by those skilled in the art are also possible.

  FIG. 4 shows an axial sectional view of a part of a valve body of a poppet valve according to another embodiment (part 1). In addition, about the site | part corresponding to FIG. 3, it shows with the same code | symbol. As shown in FIG. 4, the thin wall portion A may be arranged near the radial center of the umbrella portion 302. FIG. 5 shows an axial sectional view of a part of a valve body of a poppet valve according to another embodiment (part 2). In addition, about the site | part corresponding to FIG. 3, it shows with the same code | symbol. As shown in FIG. 5, the valve body 30 may be formed so that the thickness gradually decreases from the umbrella portion 302 toward the curved portion R2 (from the radially inner side to the radially outer side). Further, the curved portions R1 and R2 need not be arranged.

  The actuator for the poppet valve 3 is not particularly limited. For example, a solenoid may be used. The arrangement direction of the poppet valve 3 is not particularly limited. For example, the poppet valve 3 may be arranged so that the valve shaft 31 faces the horizontal direction. In the above embodiment, the valve assembly 1 is used for the EGR valve. However, the valve assembly 1 may be used for various valves such as an intake side turbo bypass valve, a throttle valve, an exhaust brake valve, and an exhaust throttle valve.

  Hereinafter, the result of the FEM (Finite Element Method) analysis performed on the analysis model (example) of the poppet valve 3 shown in FIGS. 1 to 3 will be described. As analysis software, CATIA (registered trademark) -analysis simulation was used. In the example, the thickness T1 of the thin portion A shown in FIG. 3 was 1.1 mm. The thickness T4 of the umbrella part 302 was 1.6 mm. The thickness T3 of the contact part 301 was 1.4 mm. The distance L1 from the outer edge of the contact portion 301 to the inner edge of the groove B was 5.3 mm. An intersection angle θ1 between the extending direction of the upper surface of the contact portion 301 and the extending direction of the upper surface of the thin portion A (tangential direction of the upper surface of the curved portion R2 in the thin portion A) was set to 35 °. The biasing force F1 of the coil spring 52 at the time of closing the valve shown in FIG. The maximum value of the exhaust gas pressure F2 was set to 66.7 kPa.

  For comparison, the same FEM analysis was performed on an analysis model (comparative example) of a conventional poppet valve in which the thin portion A, that is, the groove B is not disposed, as indicated by a dotted line in FIG. Note that the thicknesses T3 and T4 and the intersection angle θ1 shown in FIG.

  As a result of the FEM analysis, in the case of the comparative example, the maximum stress in the circle α portion shown in FIG. 3 was 13.3 MPa. Moreover, the maximum stress of the circle β portion (mounting portion 300) was 31.8 MPa. On the other hand, in the case of the example, the maximum stress of the circle α portion (thin wall portion A) shown in FIG. 3 was 13.8 MPa. Moreover, the maximum stress of the circle β portion (mounting portion 300) was 29.7 MPa.

  Thus, in contrast to the comparative example, in the example, the maximum stress in the circle β portion was larger. Further, in the example, the maximum stress in the circle β portion was smaller than that in the comparative example. According to the example, the stress concentration on the circle β portion (attachment portion 300) at the time of valve closing could be alleviated.

  1: valve assembly, 2: housing, 3: poppet valve, 20: EGR passage, 21: recess, 21a: spring seat, 22: valve shaft insertion hole, 30: valve body, 31: valve shaft, 51: axial bearing, 52: Coil spring, 53: Motor, 54: Valve seat, 300: Mounting portion, 301: Abutment portion, 302: Umbrella portion, 310: Shaft body, 310a: Step portion, 311: Flange portion, 311a: Spring seat, 530: Motor side shaft, A: Thin portion, B: Groove, R1: Curved portion, R2: Curved portion.

Claims (3)

A valve stem;
A valve body having an attachment portion attached to the valve shaft, and capable of being seated on and separated from the valve seat;
A poppet valve comprising:
The valve body has a contact portion that contacts the valve seat, and an umbrella portion interposed between the contact portion and the attachment portion,
Of the valve body, the thinnest part having the smallest thickness is disposed at the boundary between the contact part and the umbrella part ,
The poppet valve is characterized in that the thickness of the umbrella portion gradually increases from the thin portion toward the boundary with the attachment portion . The poppet valve according to claim 1, wherein the valve body is elastically deformed by an impact when the valve body is seated on the valve seat . A valve assembly comprising the poppet valve according to claim 1.

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