JP2015086947A - Valve assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve assembly capable of easily improving its cushioning performance.SOLUTION: A valve assembly 1 includes a valve seat 23, a poppet valve 3 having a valve element 30 capable of sitting/separating on/from the valve seat 23 and a valve stem 31 continuing into the valve element 30 and having a valve-side screw part 311, and movable in the axial direction of the valve stem 31, a driving member 40 having a drive-side screw part 400a to be threaded to the valve-side screw part 311, adapted to be moved around its axis to transmit driving force to the poppet valve 3, and movable in the axial direction of the valve stem 31, and a cushioning spring part 5 for elastically suppressing the movement of the driving member 40 in the axial direction of the valve stem 31, the cushioning spring part 5 having nonlinearity such that its spring constant is changed with the displacement. When the rotation of the driving member 40 is not stopped although the valve element 30 sits on the valve seat 23 to stop the movement of the poppet valve 3, the driving member 40 is moved in the axial direction of the valve stem 31 against the energizing force of the cushioning spring part 5.

Description

  The present invention relates to a valve assembly that is disposed in a gas passage such as an EGR (Exhaust Gas Recirculation) passage and can adjust the flow rate of the gas.

  Patent Document 1 discloses a valve assembly including a motor, a spur gear, a poppet valve, and a valve seat. The female screw of the spur gear and the male screw of the poppet valve are screwed together. The rotational force of the motor is transmitted to the poppet valve via the spur gear. For this reason, the poppet valve can reciprocate vertically. The valve body of the poppet valve can be seated and separated from the valve seat from below.

  If the valve element is seated on the valve seat when the valve is closed, the motor stops immediately. However, the drive shaft of the motor continues to rotate due to inertial force. For this reason, the spur gear also continues to rotate. However, the valve body is already in contact with the valve seat. Therefore, even if the spur gear continues to rotate, the poppet valve cannot move upward. Therefore, an impact is applied to the spur gear and the motor.

  Therefore, a play (gap) is set between the female screw of the spur gear and the male screw of the poppet valve. Even if the spur gear continues to rotate due to the inertial force, the spur gear can be allowed to rotate by the play. For this reason, it can suppress that an impact is added to a spur gear or a motor.

JP 2009-197765 A

  According to the valve assembly of the same document, it is possible to improve the shock absorbing performance against the spur gear and the motor by increasing the backlash. However, when the play is increased, the time lag when the driving force is transmitted from the motor to the poppet valve becomes large. That is, the responsiveness of the poppet valve is deteriorated. Thus, in the case of the valve assembly of the same document, it is difficult to improve the buffer performance. Therefore, an object of the present invention is to provide a valve assembly that can easily improve the buffer performance.

  (1) In order to solve the above-mentioned problems, a valve assembly of the present invention includes a valve seat, a valve body that can be seated on and separated from the valve seat, and a valve shaft that has a valve-side threaded portion connected to the valve body A poppet valve that is movable in the axial direction of the valve shaft, and a drive-side screw portion that is screwed into the valve-side screw portion, and rotates around its own axis. A driving member capable of transmitting a driving force and movable in the axial direction of the valve shaft; and elastically restraining the driving member from moving in the axial direction of the valve shaft; and a spring according to the displacement A buffer spring part having non-linearity with a constant changing, and even if the movement of the poppet valve stops due to the valve body seated on the valve seat, the rotation of the drive member does not stop, The drive member moves in the axial direction of the valve shaft against the biasing force of the buffer spring portion. That. Here, “displacement” refers to elastic deflection with respect to a no-load state (natural length state).

  The poppet valve can reciprocate in the axial direction of the valve shaft. When the valve element is seated on the valve seat, the movement of the poppet valve stops. However, the drive member may continue to rotate due to, for example, inertial force. In this case, according to the valve assembly of the present invention, instead of the non-movable poppet valve, the drive member moves in the axial direction of the valve shaft against the urging force of the buffer spring portion. For this reason, it can suppress that an impact is added to a drive member. In addition, the buffer performance can be easily improved by appropriately adjusting the shape, dimensions, and the like of the buffer spring portion.

  Moreover, the buffer spring part has nonlinearity. That is, when the buffer spring portion is elastically displaced, in other words, when the drive member moves in the axial direction of the valve shaft, the spring constant is not constant. For this reason, the buffer performance can be easily adjusted.

  Further, according to the valve assembly of the present invention, it is not necessary to intentionally set a backlash between the valve side screw portion and the drive side screw portion in order to improve the buffer performance. For this reason, the responsiveness of the poppet valve is good.

  (2) In the configuration of (1), it is preferable that the spring constant increases as the displacement of the buffer spring portion increases. The spring constant of the buffer spring portion of this configuration increases as the displacement of the buffer spring portion increases. For this reason, compared to the case where the spring constant is constant regardless of displacement (compared to the case where the buffer spring portion has linearity), the displacement amount of the buffer spring portion when a predetermined load is applied, that is, the shaft The length can be reduced. That is, the buffer spring portion can be reduced in size. Further, according to this configuration, the spring constant in the small displacement region (for example, the moment when the valve element is seated on the valve seat) can be reduced. For this reason, it is possible to suppress a large impact from being applied to the driving member in the small displacement region.

  (3) In the configuration of (2) above, it is preferable that the buffer spring portion is a conical coil spring. According to this configuration, the buffering performance can be easily adjusted so that the spring constant gradually increases from the small displacement region to the large displacement region (for example, after the valve element is seated on the valve seat).

  (4) In the configuration according to any one of (1) to (3) above, a valve closing spring portion that biases the valve body in a valve closing direction is provided, and the valve body is seated on the valve seat In this state, the valve body is pressed against the valve seat by the urging force of the valve closing spring portion, and at least one of the urging force of the buffer spring portion and the driving force of the driving member is the valve closing spring. It is better to have a configuration that assists the urging force of the part. Here, the “valve closing direction” refers to a direction in which the valve body approaches the valve seat.

  According to this configuration, in the valve-closed state, the valve body can be brought into pressure contact with the valve seat mainly by the biasing force of the valve-closing spring portion and by the at least one of the biasing force of the buffer spring portion and the driving force of the driving member. it can. For this reason, it is difficult for fluid to leak from between the valve body and the valve seat. Therefore, according to the valve assembly of this configuration, the sealing performance in the closed state is enhanced.

  (5) In the configuration according to any one of (1) to (4), the driving member includes a bearing having an outer ring and an inner ring that is disposed radially inside the outer ring and is rotatable with respect to the outer ring. It is better to be able to rotate around its own axis together with the inner ring and to move in the axial direction of the valve shaft with respect to the inner ring. According to this structure, rotation of a drive member is securable with a bearing.

  (6) In the configuration of (5) above, it is preferable that the buffer spring portion is interposed between the drive member and the inner ring. When the drive member moves in the axial direction of the valve shaft, the distance between the drive member and the inner ring changes. In this regard, the buffer spring portion of this configuration is interposed between the drive member and the inner ring. For this reason, the buffer spring part can suppress that an impact is applied to the drive member.

  (7) In the configuration of any one of the above (1) to (6), it is preferable to include a sensor that detects the position of the poppet valve in the axial direction of the valve shaft. According to this configuration, the position of the poppet valve, that is, the opening degree can be confirmed by the sensor.

  ADVANTAGE OF THE INVENTION According to this invention, the valve assembly which can improve a buffer performance easily can be provided.

It is an up-down direction sectional view in the valve opening state of the valve assembly used as one embodiment of the valve assembly of the present invention. FIG. 3 is a vertical sectional view of the valve assembly in a closed state. It is an enlarged view in the frame III of FIG. It is an enlarged view in the frame IV of FIG. It is an enlarged view of the drive member vicinity in a 2nd position. It is a graph which shows the displacement-load characteristic of a conical coil spring. It is an enlarged view near the drive member in the 1st position of the valve assembly of other embodiments.

  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 a vertical cross-sectional view of the valve assembly of the present embodiment in a valve open state. FIG. 2 is a vertical sectional view of the valve assembly in a closed state. FIG. 3 shows an enlarged view in the frame III of FIG. FIG. 4 shows an enlarged view in the frame IV of FIG.

  In the valve-closed state, as will be described later, the drive member 40 can be moved in the vertical direction in a region between the first position and the second position below the first position. . The driving member 40 shown in FIGS. 2 and 4 is disposed at the first position.

  As shown in FIGS. 1 to 4, the valve assembly 1 includes a housing 2, a poppet valve 3, a power transmission unit 4, a conical coil spring 5, a seal member 60, an anti-rotation member 61, and a motor 90. , A sensor 92, a control device 93, and a coil spring 94. The coil spring 94 is included in the concept of the “valve closing spring portion” of the present invention.

[Housing 2, Seal member 60, Non-rotating member 61, Motor 90, Sensor 92]
The housing 2 includes a passage housing 20, a partition wall 21, a motor housing 22, and a valve seat 23. The passage housing 20 includes an EGR passage 200, a concave portion 201, and a boss portion 202. The EGR passage 200 is L-shaped from the lower side (upstream side) to the right side (downstream side). In the valve open state shown in FIG. 1, exhaust gas flows through the EGR passage 200. A ring-shaped valve seat mounting portion 200 a is formed at the lower end (upstream end) of the EGR passage 200. The valve seat 23 is fixed to the valve seat mounting portion 200a. The valve seat 23 has a ring shape.

  The recess 201 is arranged on the upper side of the EGR passage 200. The recess 201 opens upward. A ring-shaped bearing housing portion 201 a is formed on the bottom wall of the recess 201. As will be described later, the recess 201 accommodates the power transmission unit 4, the drive shaft 900 of the motor 90, and the drive gear 901.

  The boss portion 202 is disposed below the bearing housing portion 201a. The boss portion 202 has a short-axis cylindrical shape. A valve shaft insertion hole 202 a having a perfectly circular cross section is formed in the bottom wall of the boss portion 202. The valve shaft insertion hole 202a penetrates the bottom wall in the vertical direction. A ring-shaped seal member accommodating portion 202 b is formed on the upper edge of the inner peripheral surface of the boss portion 202.

  The seal member 60 has a ring shape. The seal member 60 is accommodated in the seal member accommodating portion 202b. As will be described later, the valve shaft 31 of the poppet valve 3 is inserted inside the seal member 60 in the radial direction. The seal member 60 hermetically seals the inside of the boss 202 and the recess 201. The seal member 60 suppresses the exhaust gas that has entered the boss portion 202 from the EGR passage 200 through the valve shaft insertion hole 202a from leaking into the recess 201.

  The partition wall 21 covers the recess 201 from above. On the upper surface of the partition wall 21, a ring-shaped spring seat 210 is formed. A ring-shaped bearing housing portion 211 is formed on the lower surface of the partition wall 21. A valve shaft insertion hole 213 having a perfect circular cross section is formed in the partition wall 21. The valve shaft insertion hole 213 penetrates the partition wall 21 in the vertical direction. The partition wall 21 is formed with a motor insertion hole 212 having a perfectly circular cross section. The motor insertion hole 212 penetrates the partition wall 21 in the vertical direction. The motor insertion hole 212 is arranged on the right side of the valve shaft insertion hole 213.

  The rotation preventing member 61 has a ring shape. The rotation preventing member 61 is fixed to the valve shaft insertion hole 213. The anti-rotation member 61 is formed with an anti-rotation hole 610 having a square cross section. The anti-rotation hole 610 penetrates the anti-rotation member 61 in the vertical direction.

  The motor housing 22 is disposed above the partition wall 21. A motor 90 is accommodated in the motor housing 22. The motor 90 includes a drive shaft 900 and a drive gear 901. The drive shaft 900 can rotate around its own axis. The drive gear 901 is fixed to the lower end of the drive shaft 900. The drive shaft 900 and the drive gear 901 enter the recess 201 via the motor insertion hole 212. The motor housing 22 accommodates the lower part of the sensor 92. The sensor 92 includes a contact portion 920. The contact portion 920 can detect the vertical position of a detent portion 312 described later.

  The control device 93 is electrically connected to the motor 90 and the sensor 92. The vertical position of the rotation stopper 312 is transmitted from the sensor 92 to the control device 93. The control device 93 determines the opening degree of the poppet valve 3 to be described later, based on the vertical position of the rotation preventing portion 312. The control device 93 issues a drive instruction to the motor 90 based on the opening degree.

[Power transmission unit 4, conical coil spring 5]
The power transmission unit 4 includes a drive member 40, a pair of upper and lower bearings 41, and a speed change member 42. The power transmission unit 4 is accommodated in the recess 201. The speed change member 42 is supported by the bottom wall of the recess 201 and the partition wall 21 so as to be rotatable about its own axis. The transmission member 42 includes a large diameter gear 420 and a small diameter gear 421. The large diameter gear 420 meshes with the drive gear 901 of the motor 90. The small diameter gear 421 is arranged on the upper side of the large diameter gear 420. The small diameter gear 421 is disposed coaxially with the large diameter gear 420.

  The pair of upper and lower bearings 41 are so-called rolling bearings. The upper bearing 41 is disposed in the bearing accommodating portion 211 of the partition wall 21. The bearing 41 includes an outer ring 410, an inner ring 411, and a large number of balls 412. The outer ring 410 is fixed to the bearing housing portion 211. The inner ring 411 is disposed on the radially inner side of the outer ring 410. Many balls 412 are interposed between the inner ring 411 and the outer ring 410. The inner ring 411 can rotate with respect to the outer ring 410. The lower bearing 41 is disposed in the bearing housing portion 201 a of the recess 201. The outer ring 410 is fixed to the bearing housing portion 201a.

  The drive member 40 includes a cylindrical portion 400 and a flange portion 401. The cylindrical portion 400 extends in the vertical direction. As will be described later, the valve shaft 31 of the poppet valve 3 is inserted inside the cylindrical portion 400 in the radial direction. The inner peripheral surface of the cylindrical portion 400 has a perfect circular cross section. On the inner peripheral surface of the cylindrical portion 400, a driving side screw portion 400a is formed. Near the upper end of the outer peripheral surface of the cylindrical portion 400, an inner ring 411 of the upper bearing 41 is mounted. Near the lower end of the outer peripheral surface of the cylindrical portion 400, an inner ring 411 of the lower bearing 41 is mounted. The cylindrical portion 400, that is, the driving member 40 is rotatable about its own axis with respect to the pair of upper and lower outer rings 410 together with the pair of upper and lower inner rings 411. Further, the cylindrical portion 400, that is, the drive member 40 can slide in the vertical direction with respect to the pair of upper and lower inner rings 411. That is, a mechanism that restricts relative rotation and allows relative vertical movement between the cylindrical portion 400 and the pair of upper and lower inner rings 411 (for example, a predetermined clearance or a vertical extension). An uneven portion (such as serration) is arranged.

  The flange portion 401 protrudes radially outward from the outer peripheral surface of the cylindrical portion 400. A gear portion 401 a is formed on the outer edge of the flange portion 401. The gear portion 401 a meshes with the small diameter gear 421 of the transmission member 42. As will be described later, the drive member 40 is movable in the vertical direction from the first position to the second position. The vertical lengths of the gear portion 401a and the small-diameter gear 421 are set so that the meshing state can be secured even if the driving member 40 moves. On the lower surface of the flange portion 401, a ring-shaped spring seat 401b is formed. As shown in FIG. 4, the upper surface of the flange 401 is in contact with the inner ring 411 of the upper bearing 41 at the first position.

  The conical coil spring 5 has non-linearity in which the spring constant changes according to the displacement. The conical coil spring 5 has a tapered shape that is pointed from the upper side to the lower side. The conical coil spring 5 is interposed between the spring seat 401 b of the flange portion 401 and the inner ring 411 of the lower bearing 41. The conical coil spring 5 urges the flange portion 401, that is, the drive member 40 upward with respect to the inner ring 411.

[Poppet valve 3, coil spring 94]
The poppet valve 3 includes a valve body 30 and a valve shaft 31. The valve body 30 has a disk shape. The outer diameter of the valve body 30 is larger than the inner diameter of the valve seat 23. The valve body 30 can be seated on and separated from the valve seat 23 from below.

  The valve shaft 31 protrudes upward from the radial center of the upper surface of the valve body 30. The valve shaft 31 extends in the vertical direction. The valve shaft 31 includes a shaft main body 310, a valve-side screw portion 311, a detent portion 312, and a flange portion 313. The shaft body 310 has a perfect circular cross section. The shaft main body 310 is connected to the valve body 30. The shaft main body 310 passes through the valve shaft insertion hole 202a and the seal member 60 from the lower side to the upper side. The upper part of the shaft body 310 is inserted into the cylindrical part 400. The valve-side screw portion 311 is formed on the outer peripheral surface of the upper portion of the shaft main body 310. The valve side screw part 311 and the drive side screw part 400a are screwed together. The rotation stopper 312 is disposed on the upper side of the shaft main body 310. The anti-rotation part 312 has a square cross section. The anti-rotation portion 312 is inserted through the anti-rotation hole 610. By the insertion, the valve shaft 31 can be prevented from rotating around its own axis. The upper end of the rotation preventing portion 312 is in contact with the contact portion 920 of the sensor 92. The flange portion 313 is disposed on the upper side of the rotation preventing portion 312. The flange portion 313 has a cup shape that opens upward. In the valve closing state shown in FIG. 2, the lower portion of the sensor 92 is accommodated in the flange portion 313. A ring-shaped spring seat 313 a is formed on the upper edge of the flange portion 313. The spring seat 313a of the flange portion 313 and the spring seat 210 of the partition wall 21 face each other in the vertical direction.

  The coil spring 94 is interposed between the spring seat 313 a of the flange portion 313 and the spring seat 210 of the partition wall 21. The coil diameter of the coil spring 94 is constant over the entire length in the axial direction. The coil spring 94 urges the flange portion 313, that is, the poppet valve 3, upward (in the valve closing direction) with respect to the partition wall 21.

<Valve assembly movement>
Next, the movement of the valve assembly of this embodiment will be described. FIG. 5 shows an enlarged view of the vicinity of the driving member at the second position. 5 corresponds to FIGS. 3 and 4. FIG. In FIG. 5, the drive member 40 and the conical coil spring 5 at the first position shown in FIG.

  First, the case where the valve assembly 1 is switched from the valve open state shown in FIG. 1 to the valve closed state (first position) shown in FIG. 2 will be described. The control device 93 drives the motor 90. The driving force (rotational force) of the driving shaft 900 of the motor 90 is transmitted to the flange portion 401, that is, the driving member 40 via the driving gear 901, the large diameter gear 420, the small diameter gear 421, and the gear portion 401a. For this reason, the drive member 40, that is, the cylindrical portion 400 rotates around its own axis while being supported by the pair of upper and lower bearings 41. Here, the drive side screw part 400a and the valve side screw part 311 are screwed together. For this reason, when the cylindrical portion 400 rotates, the valve shaft 31, that is, the poppet valve 3 moves upward. The poppet valve 3 is also moved upward by an upward biasing force applied from the coil spring 94. When the valve body 30 is seated on the valve seat 23 from below, the EGR passage 200 is blocked. In this way, the valve opening state shown in FIG. 1 is switched to the valve closing state shown in FIG.

  Next, the case where the drive member 40 is switched from the first position shown in FIGS. 2 and 4 to the second position shown in FIG. 5 in the valve closed state will be described. As shown in FIGS. 2 and 4, the control device 93 stops the motor 90 at the moment when the valve body 30 is seated on the valve seat 23. That is, the control device 93 cuts off the power supply to the motor 90. However, the drive shaft 900 continues to rotate due to inertial force. For this reason, the drive member 40 also continues to rotate. However, the valve body 30 is already in contact with the valve seat 23. Therefore, even if the drive member 40 continues to rotate, the poppet valve 3 cannot move upward. Therefore, as shown in FIG. 5, instead of the poppet valve 3 moving upward, the drive member 40 moves downward. When the drive member 40 moves downward, the conical coil spring 5 is elastically compressed from the axial direction (vertical direction). By the elastic deformation, the conical coil spring 5 can buffer an impact applied to the drive member 40, the transmission member 42, the motor 90, and the like.

  The drive member 40 stops at any position between the first position shown in FIG. 4 and the second position shown in FIG. 5 according to the magnitude of the inertial force accompanying the stop of the motor 90. In the second position, the lower surface of the cylindrical portion 400 is in contact with the seal member 60 (see FIG. 2).

  Even when the rotation of the drive shaft 900 due to the inertial force is stopped, the urging force is accumulated in the coil spring 94. For this reason, the valve body 30 can be brought into pressure contact with the valve seat 23. Further, the conical coil spring 5 stores an urging force due to the compression. For this reason, the conical coil spring 5 biases the drive member 40 upward. Therefore, the valve body 30 can be pressed against the valve seat 23. Thus, in the valve-closed state, the valve body 30 can be brought into pressure contact with the valve seat 23 mainly by the biasing force of the coil spring 94 and by the biasing force of the conical coil spring 5.

  When the valve assembly 1 is switched from the valve-closed state shown in FIG. 2 to the valve-opened state shown in FIG. 1, the control device 93 drives the motor 90 in the opposite direction to the case of switching from the valve-opened state to the valve-closed state. .

<Characteristics of conical coil spring 5>
Next, the characteristics of the conical coil spring of the valve assembly of this embodiment will be described. FIG. 6 shows the displacement-load characteristics of the conical coil spring. As shown by the curve α in FIG. 6, the spring constant of the conical coil spring 5 is not constant. The conical coil spring 5 has non-linearity. As the displacement increases (the load increases), the spring constant increases. That is, the value obtained by first-order differentiation of the curve α with the displacement and the value obtained by second-order differentiation of the curve α with the displacement are both positive.

  On the other hand, as shown by a straight line β in FIG. 6, a cylindrical coil spring (equal wire diameter (the wire diameter of the spring material is constant), equal pitch (a constant pitch between the spring materials adjacent in the axial direction) is provided. The spring constant of the coil spring is constant. The cylindrical coil spring has linearity.

  When a predetermined load F1 (for example, the maximum load applied to the drive member 40 when the drive shaft 900 continues to rotate due to inertial force) is applied to the drive member 40, the cylindrical coil spring is compressed by the displacement amount δ0. The On the other hand, the conical coil spring 5 is compressed by a displacement amount δ1 (<δ0). Thus, when the conical coil spring 5 is used as a buffer for the drive member 40, the speed change member 42, the motor 90, etc., the amount of displacement, that is, the axial length (length in the vertical direction), compared to the case where the cylindrical coil spring is used. Can be reduced.

  As shown in FIG. 6, in the small displacement region (0 <displacement amount ≦ displacement amount δ2 region), the conical coil spring 5 has a smaller spring constant than the cylindrical coil spring. For this reason, the spring constant at the first position shown in FIG. 4 (the moment when the valve body 30 is seated on the valve seat 23) can be reduced. Therefore, it is possible to suppress a large impact from being applied to the drive member 40, the transmission member 42, the motor 90, and the like at the first position.

<Effect>
Next, the function and effect of the valve assembly of this embodiment will be described. As shown in FIGS. 1 and 2, the poppet valve 3 can reciprocate in the vertical direction (the axial direction of the valve shaft 31). When the valve body 30 is seated on the valve seat 23, the upward movement of the poppet valve 3 is stopped. Further, the rotation of the motor 90 is also stopped. However, the drive member 40 continues to rotate due to inertial force. In this case, according to the valve assembly 1 of the present embodiment, as shown in FIG. 5, instead of the poppet valve 3 that cannot move upward, the drive member 40 is placed on the lower side against the urging force of the conical coil spring 5. Move to. Therefore, when the drive member 40 cannot move downward, in other words, compared with the case where the drive member 40 stops suddenly, it is possible to suppress the impact on the drive member 40, the speed change member 42, the motor 90, and the like. it can. Further, the wire diameter of the spring material forming the conical coil spring 5, the pitch between the adjacent spring materials in the axial direction, the axial length of the conical coil spring 5, the coil diameter, the inclination angle of the taper of the coil with respect to the axial direction, and the like are appropriately adjusted. By doing so, the buffering performance can be easily improved.

  As shown in FIGS. 3 to 5, there are only two contact points between the conical coil spring 5 and the drive member 40, that is, the spring seat 401 b and the vicinity of the inner ring 411 of the lower bearing 41. For this reason, a sufficient clearance can be secured between the conical coil spring 5 and the cylindrical portion 400. Therefore, the conical coil spring 5 and the cylindrical portion 400 are unlikely to interfere with each other.

  Moreover, as shown in FIG. 6, the conical coil spring 5 has non-linearity. Therefore, according to the valve assembly 1 of the present embodiment, the buffering performance with respect to the drive member 40, the transmission member 42, the motor 90, etc. can be easily adjusted by adjusting the shape of the curve α shown in FIG. .

  As shown in FIG. 6, as the displacement of the conical coil spring 5 increases, the spring constant of the conical coil spring 5 increases. For this reason, the amount of displacement when the predetermined load F1 is applied to the drive member 40 can be reduced. Therefore, the axial length of the conical coil spring 5 can be reduced.

  Further, as shown in FIG. 6, the spring constant of the conical coil spring 5 in the small displacement region is small. For this reason, it is possible to suppress a large impact from being applied to the drive member 40, the transmission member 42, the motor 90, etc. at the moment when the valve body 30 is seated on the valve seat 23.

  As shown in FIG. 5, according to the valve assembly 1 of the present embodiment, the valve body 30 is pressed against the valve seat 23 by the urging force of the coil spring 94 and the urging force of the conical coil spring 5 in the valve closed state. doing. For this reason, it is difficult for the exhaust gas to leak from between the valve element 30 and the valve seat 23 in the valve closed state. That is, according to the valve assembly 1 of this embodiment, the sealing performance in the closed state is enhanced. Moreover, as shown in FIGS. 3-5, according to the valve assembly 1 of this embodiment, rotation of the drive member 40 is securable by a pair of upper and lower bearings 41. FIG.

  As shown in FIG. 5, according to the valve assembly 1 of the present embodiment, the conical coil spring 5 is interposed between the drive member 40 and the inner ring 411 of the lower bearing 41. For this reason, the conical coil spring 5 can suppress the drive member 40 from moving downward due to its contraction.

  Further, the drive member 40 and the inner ring 411 rotate in synchronization. For this reason, the possibility that a torsional load is applied to the conical coil spring 5 due to the displacement of the drive member 40 and the inner ring 411 in the circumferential direction is small.

  As shown in FIGS. 1 and 2, the valve assembly 1 of this embodiment includes a sensor 92. For this reason, the controller 93 can confirm the vertical position of the poppet valve 3, that is, the opening degree. Further, the control device 93 can control the opening of the poppet valve 3, that is, the flow rate of the exhaust gas, in the open / close region from the valve open state shown in FIG. 1 to the valve closed state shown in FIG. 2.

  As shown in FIGS. 3 to 5, according to the valve assembly 1 of the present embodiment, in order to improve the buffer performance, the valve-side screw portion 311 and the drive-side screw portion 400a are intentionally inserted. There is no need to set a backlash (gap). For this reason, the response of the poppet valve 3 to the operation of the motor 90 is good.

  Further, as shown in FIG. 5, according to the valve assembly 1 of the present embodiment, even when the inertial force applied to the drive shaft 900 when the motor 90 stops when the valve is closed is large, in other words, the poppet when the valve is closed. Even when the moving speed of the valve 3 is high, the conical coil spring 5 can buffer the impact applied to the drive member 40, the transmission member 42, the motor 90, and the like. For this reason, the moving speed of the poppet valve 3 when the valve is closed can be increased. Therefore, the EGR passage 200 can be shut off quickly.

  In the closed state shown in FIG. 2, the lower portion of the sensor 92 is accommodated in the flange portion 313. For this reason, the valve assembly 1 can be reduced in size while ensuring the axial length (vertical length) of the coil spring 94.

<Others>
The embodiment of the valve assembly of the present invention has 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.

  The number of springs arranged in the buffer spring portion is not particularly limited. FIG. 7 shows an enlarged view of the vicinity of the drive member at the first position of the valve assembly according to another embodiment. In addition, about the site | part corresponding to FIG. 4, it shows with the same code | symbol.

  As shown in FIG. 7, a small-diameter spring seat 401 c and a large-diameter spring seat 401 d are formed on the lower surface of the flange portion 401. A flange member 95 is provided around the outer peripheral surface of the cylindrical portion 400. The flange member 95 is in contact with the inner ring 411 of the lower bearing 41. The outer peripheral surface of the cylindrical portion 400 is in sliding contact with the inner peripheral surface of the flange member 95. A small-diameter spring seat 950 and a large-diameter spring seat 951 are formed on the upper surface of the flange member 95. The buffer spring portion 5 a includes a cylindrical small diameter coil spring 50 and a cylindrical large diameter coil spring 51. The small diameter coil spring 50 is interposed between the small diameter spring seat 401 c and the small diameter spring seat 950. The large-diameter coil spring 51 is interposed between the large-diameter spring seat 401d and the large-diameter spring seat 951.

  As shown in FIG. 7, at the moment when the valve body is seated on the valve seat, the small-diameter coil spring 50 is in contact with the small-diameter spring seat 401c and the small-diameter spring seat 950. On the other hand, the large-diameter coil spring 51 is in contact with only the large-diameter spring seat 951. When an inertial force is applied to the drive shaft as the motor is stopped when the valve is closed, the drive member 40 moves downward against the urging force of the small diameter coil spring 50. When the drive member 40 moves downward, the large-diameter coil spring 51 contacts the large-diameter spring seat 401d. After this contact, the drive member 40 moves downward against the urging force of the small diameter coil spring 50 and the large diameter coil spring 51. As described above, in the case of the valve assembly of FIG. 7, the non-linearity of the buffer spring portion 5 a is ensured by the small diameter coil spring 50 and the large diameter coil spring 51. Note that, as indicated by a broken line γ in FIG. 6, the drive member 40 is supported by both the small-diameter coil spring 50 and the large-diameter coil spring 51 than when the drive member 40 is supported by the small-diameter coil spring 50 alone. The spring constant of the buffer spring portion 5a becomes larger when it is present. Thus, you may arrange | position a some spring in the buffer spring part 5a. The plurality of springs may be arranged in series or in parallel.

  Further, as the spring for the buffer spring portion 5a, a coil spring having an unequal pitch (a pitch between spring members adjacent in the axial direction is not constant) or a coil spring in which the diameter of the wire changes in a tapered shape may be used. If it carries out like this, the nonlinearity of the buffer spring part 5a can be ensured with a single coil spring. Further, the coil spring may bias the drive member 40 not by a compressive force but by a tensile force.

  In the above embodiment, as shown in FIG. 5, the valve body 30 is brought into pressure contact with the valve seat 23 by the urging force of the conical coil spring 5 in the valve closed state. However, the valve body 30 may be brought into pressure contact with the valve seat 23 by the driving force of the motor 90. Specifically, the valve body 30 may be brought into pressure contact with the valve seat 23 by driving the motor 90 in a direction in which the cylindrical portion 400 is in pressure contact with the seal member 60 at the second position shown in FIG. Further, the motor 90 is continuously driven from the valve-opened state shown in FIG. 3 to the valve-closed second position shown in FIG. 5 through the valve-closed first position shown in FIG. Also good. In this case, the driving member 40 moves from the first position to the second position by the driving force of the motor 90, not by the inertial force accompanying the stop of the motor 90. Further, the valve body 30 may be brought into pressure contact with the valve seat 23 by the biasing force of the conical coil spring 5 and the driving force of the motor 90.

  The bearing 41 shown in FIGS. 3 to 5 may be a sliding bearing. Further, the speed change member 42 shown in FIGS. 1 and 2 may not be arranged. That is, the drive gear 901 and the gear portion 401a may be directly meshed with each other. Further, instead of the speed change member 42, a driving force may be transmitted from the driving gear 901 to the gear portion 401a by using a power transmission mechanism such as a link mechanism, a chain-sprocket mechanism, a belt-pulley mechanism or the like.

  Further, the control device 93 may check the vertical position of the poppet valve 3 using an encoder of the motor 90 instead of the sensor 92. The arrangement direction of the valve assembly 1 is not particularly limited. For example, the upper side in FIG. 1 may be the lower side, the left side, the right side, the front side, the rear side, and the like.

1: Valve assembly.
2: housing, 20: passage housing, 200: passage, 200a: valve seat mounting portion, 201: recessed portion, 201a: bearing housing portion, 202: boss portion, 202a: valve shaft insertion hole, 202b: seal member housing portion, 21 : Partition wall, 210: spring seat, 211: bearing housing, 212: motor insertion hole, 213: valve shaft insertion hole, 22: motor housing, 23: valve seat.
3: Poppet valve, 30: Valve body, 31: Valve shaft, 310: Shaft body, 311: Valve side screw portion, 312: Non-rotating portion, 313: Flange portion, 313a: Spring seat.
4: power transmission part, 40: driving member, 400: cylindrical part, 400a: driving side screw part, 401: flange part, 401a: gear part, 401b: spring seat, 401c: small diameter spring seat, 401d: large diameter spring seat 41: bearing, 410: outer ring, 411: inner ring, 412: ball, 42: speed change member, 420: large diameter gear, 421: small diameter gear.
5: conical coil spring, 5a: buffer spring portion, 50: small diameter coil spring, 51: large diameter coil spring.
60: seal member, 61: anti-rotation member, 610: anti-rotation hole.
90: motor, 900: drive shaft, 901: drive gear, 92: sensor, 920: contact part, 93: control device, 94: coil spring (valve closing spring part), 95: flange member, 950: small diameter spring seat, 951: Large diameter spring seat.

Claims (7)

A valve seat,
A poppet valve having a valve body that can be seated on and separated from the valve seat, and a valve shaft that is connected to the valve body and has a valve-side screw portion, and is movable in the axial direction of the valve shaft;
A drive side screw portion that is screwed to the valve side screw portion, and a drive force that can be transmitted to the poppet valve by rotating around its own axis and that is movable in the axial direction of the valve shaft Members,
A buffer spring portion having non-linearity in which the drive member is elastically suppressed from moving in the axial direction of the valve shaft and the spring constant changes in accordance with the displacement;
With
If the rotation of the drive member does not stop even when the movement of the poppet valve stops due to the valve body seated on the valve seat, the drive member is against the biasing force of the buffer spring portion. A valve assembly that moves in the axial direction of the valve shaft.   The valve assembly according to claim 1, wherein the spring constant increases as the displacement of the buffer spring portion increases.   The valve assembly according to claim 2, wherein the buffer spring portion is a conical coil spring. A valve closing spring portion for urging the valve body in the valve closing direction;
In the valve closing state where the valve body is seated on the valve seat, the valve body is pressed against the valve seat by the biasing force of the valve closing spring portion,
4. The valve assembly according to claim 1, wherein at least one of an urging force of the buffer spring portion and a driving force of the driving member assists the urging force of the valve closing spring portion. 5. A bearing having an outer ring and an inner ring that is disposed radially inside the outer ring and is rotatable with respect to the outer ring;
The valve assembly according to any one of claims 1 to 4, wherein the drive member is rotatable about its own axis together with the inner ring, and is movable in the axial direction of the valve axis with respect to the inner ring.   The valve assembly according to claim 5, wherein the buffer spring portion is interposed between the driving member and the inner ring.   The valve assembly according to any one of claims 1 to 6, further comprising a sensor that detects a position of the poppet valve in an axial direction of the valve shaft.

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