Fluid control device

Abstract

Provided is a fluid control device capable of minimizing fluctuation of an inter-shaft distance associated with the rotation of a valve gear. The fluid control device has a valve gear (6) fixed to a shaft (4) supporting a butterfly valve (5). An end part of the shaft (4) is fixed to a shaft mounting hole (17) of a connecting member (16) of the valve gear (6), by means of an umbrella-shaped fixing part (18). An area center of a region (A) overlapping the umbrella-shaped fixing part (18) of the shaft mounting hole (17) is on a reference straight line (S) passing through a rotation center of the shaft (4). Furthermore, in a fully closed state, the magnitude of an angle (θ2) formed by the reference straight line (S) in the closing direction with respect to a gear straight line (GL) passing through the rotation centers of a drive gear (8) for driving the valve gear (6) and the shaft (4) is equal to or less than a movable angle (θ1).

Description

Fluid Control Device

[0001] The present invention relates to a fluid control device having a valve body that is rotatable within a fluid passage of a body.

[0002] In a conventional fluid control device having a plate-shaped valve element that can rotate within a fluid passage in a body, the valve element opens and closes the fluid passage by rotating a shaft that holds the valve element. The shaft is rotated by rotating a valve gear fixed to one end of the shaft using an electric motor (see, for example, Patent Document 1).

[0003] In the fluid control device of Patent Document 1, the shaft is fixed to the valve gear by inserting the end of the shaft into a shaft mounting hole in a connecting member fixed to the valve gear, causing it to protrude slightly, and then crimping the end from the protruding side. During this crimping, the deformed portion of the end fills multiple recesses recessed radially outward in the shaft mounting hole and forms an umbrella-like covering over the side of the shaft mounting hole from which the end protrudes.

[0004] Furthermore, when molding a gear on the outer periphery of the connecting member, some of the multiple recesses in the shaft mounting hole have shapes different from the others so that when the end of the positioning pin is inserted into the shaft mounting hole of the connecting member within the molding die, the insertion posture of the connecting member relative to the positioning pin is consistent and at a specified angle in the rotational direction.

[0005] JP 2018-100598 A

[0006] However, with the device of Patent Document 1, some of the multiple recesses in the shaft mounting hole have shapes that differ from the other recesses. Therefore, when the shaft is inserted into the shaft mounting hole with a clearance fit and the end of the shaft is crimped, the central axis of the valve gear is displaced relative to the central axis of the shaft, causing eccentricity.

[0007] This deviation of the central axis causes fluctuations in the center distance (gear pitch) between the valve gear and the drive gear that drives it. The amount of fluctuation in this center distance changes depending on the rotation angle of the valve gear. This can worsen the gear meshing ratio and shorten the gear's wear life.

[0008] In view of the problems with the prior art, an object of the present invention is to minimize fluctuations in the center distance caused by rotation of the valve gear in a fluid control device.

[0009] The fluid control device of the present invention comprises a body in which a fluid passage is formed, a plate-shaped valve body that is rotatably supported by the body via a shaft and that opens and closes the fluid passage, and a valve gear that is fixed to one end of the shaft and rotated by an electric actuator.

[0010] The valve gear is configured to be rotatable within a movable angle range of less than 90° between the fully open state and the fully closed state of the valve disc by meshing with a drive gear driven by the electric actuator. The valve gear is provided with a connecting member having a shaft mounting hole through which one end of the shaft is passed.

[0011] One end of the shaft that is passed through the shaft mounting hole is fixed to the shaft mounting hole by an umbrella-shaped fixing portion that is formed by plastically deforming the shaft radially outward.

[0012] When viewed in a direction along the shaft, the center of the area of ​​the region overlapping with the umbrella-shaped fixing portion of the shaft mounting hole is on a reference line passing through the center of rotation of the shaft. Further, when viewed in a direction along the shaft, when the valve disc is in a fully closed state, the magnitude of the angle between the reference line and a gear line connecting the center of rotation of the drive gear and the center of rotation of the shaft is less than or equal to the movable angle of the valve disc in the closing direction of the valve disc.

[0013] According to the present invention, the center of the area overlapping with the umbrella-shaped fixing portion of the shaft mounting hole is located on a reference line passing through the center of rotation of the shaft, and when the valve disc is in the fully closed state, the magnitude of the angle that this reference line makes with the gear line is less than or equal to the movable angle of the valve disc in the closing direction, thereby minimizing fluctuations in the center distance that accompany rotation of the valve gear.

[0014] FIG. 5 is a front view showing the main parts of an intake control device according to one embodiment of the present invention, viewed from a direction along the shaft with the gear case cover removed. FIG. 6 is a cross-sectional view taken along line II-II of FIG. 3, showing the configuration of the vicinity of the tip of the shaft in the intake control device of FIG. 1. FIG. 7 is a diagram showing the vicinity of the tip of the shaft of FIG. 2, viewed from the tip side along the shaft. FIG. 8 is a diagram showing a connecting member of a conventional intake control device. FIG. 9 is a graph showing the change in the amount of variation in the center distance with respect to the change in opening in the intake control device of FIG. 1. FIG. 10 is a graph showing the rate of variation in the center distance obtained by differentiating the graph of FIG. 5. FIG. 11 is a diagram showing a modified connecting member that can be used in the fluid control device of FIG. 1. FIG. 12 is a diagram showing another modified connecting member that can be used in the fluid control device of FIG. 1.

[0015] An embodiment of the present invention will now be described with reference to the drawings. Fig. 1 shows the main components of an electronically controlled intake control device according to one embodiment of the fluid control device of the present invention. As shown in the figure, this intake control device 1 includes a body 3 in which an intake passage 2 serving as a fluid passage is formed, and a butterfly valve 5 serving as a plate-shaped valve element that is rotatably supported by the body 3 via a shaft 4 and opens and closes the intake passage 2.

[0016] A valve gear 6 that is rotated by an electric actuator is fixed to one end of the shaft 4. In this example, an electric motor 7 is used as the electric actuator. The valve gear 6 is configured to be rotatable within a movable angle θ1 range of less than 90°, which corresponds to the range between the fully open and fully closed states of the butterfly valve 5, by meshing with a drive gear 8 that is driven by the electric motor 7. In Figure 1, the butterfly valve 5 is shown by a dashed line in the fully closed state, with the valve gear 6 abutting against a fully closed stopper 9 on the body 3.

[0017] The electric motor 7 drives the drive gear 8 via a pinion gear 10 that is provided on the output shaft of the electric motor 7 and meshes with the drive gear 8. The drive gear 8 includes a large gear 11 that meshes with the pinion gear 10 and a small gear 12 that is fixed coaxially with the large gear 11. The valve gear 6 meshes with the small gear 12 of the drive gear 8. The gear mechanism including the valve gear 6, drive gear 8, and pinion gear 10 is housed in a gear case GC. Figure 1 shows the gear case GC with its cover removed.

[0018] A return spring 13 interposed between the valve gear 6 and the body 3 biases the valve gear 6 in the direction of the closed position (closing direction) in which the butterfly valve 5 closes the intake passage 2. A default spring 14, which is disposed inside the return spring 13 and interposed between the valve gear 6 and the body 3, biases the valve gear 6 in the direction of opening the butterfly valve 5 (opening direction) within an angular range corresponding to the closed position and a predetermined default position of the butterfly valve 5.

[0019] The valve gear 6 is rotated by the electric motor 7 against the biasing forces of the return spring 13 and the default spring 14 so that the butterfly valve 5 reaches the required opening. If the electric motor 7 becomes inoperable due to a malfunction or the like, the default spring 14 functions as a default mechanism 15 that positions the butterfly valve 5 in a default position. The opening when the butterfly valve 5 is in the default position, i.e., the default angle, is an intermediate opening angle within the range of the movable angle θ1.

[0020] The valve gear 6 is provided with a connecting member 16 for fixing the valve gear 6 to one end of the shaft 4. The connecting member 16 is provided with a shaft mounting hole 17 through which the one end is passed and fixed.

[0021] Figure 2 shows the configuration near the tip of the shaft 4. As shown in Figure 2, one end of the shaft 4 passed through the shaft mounting hole 17 is fixed in the longitudinal direction of the shaft 4 by an umbrella-shaped fixing portion 18 formed by plastically deforming the shaft 4 radially outward. The umbrella-shaped fixing portion 18 is formed by a portion located outside the diameter of one end of the shaft 4. The umbrella-shaped fixing portion 18 can be formed by spin crimping. During this process, the material of the tip of the shaft 4 is plastically deformed and flows in the direction of the arrow in the figure, forming the umbrella-shaped fixing portion 18.

[0022] 3 shows the vicinity of the tip of the shaft 4 as viewed from the tip side along the extension direction of the shaft 4. As shown in FIG. 3, the peripheral wall 19 of the shaft mounting hole 17 forms splines that curve alternately outward and inward along the outer periphery 20 of the umbrella-shaped fixing portion 18.

[0023] This spline circumscribes a circle having a diameter equal to the diameter of one end of the shaft 4 at approximately each vertex of a regular octagon centered on the rotation center P1 of the shaft 4, and forms eight recesses recessed radially outward between each circumscribed position. The eight recesses are made up of three reference recesses 21a having the same shape and five standard recesses 21b having the same shape. The reference recesses 21a are deeper radially outward than the standard recesses 21b.

[0024] The three reference recesses 21a serve as references for positioning the connecting member 16 in an appropriate position relative to the tip of the positioning pin within the mold. The deepest portions of two of the three reference recesses 21a are located on a gear straight line GL (see FIG. 1) that passes through the rotation center P2 of the drive gear 8 and the rotation center P1 of the shaft 4. In this embodiment, the deepest portion of the remaining reference recess 21a is located on a reference straight line S, which will be described later, but this is not limiting.

[0025] When forming the umbrella-shaped fixing portion 18, the material at the tip of the shaft 4 is plastically deformed by spin crimping and flows into the reference recess 21a and the standard recess 21b, thereby fixing the connecting member 16 to the tip of the shaft 4 in a predetermined posture.

[0026] The reference line S is a line that passes through the rotation center P1 of the shaft 4 and also passes through the areal center (geometric center) C of the area A (shaded portion) that overlaps with the umbrella-shaped fixing portion 18 of the shaft mounting hole 17. Furthermore, the reference line S forms an angle θ2 with the gear line GL in the direction in which the butterfly valve 5 closes, the angle being less than the movable angle θ1 described above, in the direction in which the butterfly valve 5 closes, in a fully closed state (the state shown in FIGS. 1 and 3 ) in which the butterfly valve 5 closes the intake passage 2.

[0027] The fact that the reference line S passes through the area center (geometric center) C means that when the umbrella-shaped fixing portion 18 is formed, most of the plastically deformed material of the shaft 4 flows in the direction D1 from the rotation center P1 toward the center C. This means that when the shaft 4 is plastically deformed radially outward by spin crimping and the material of the shaft 4 flows into each of the reference recesses 21 a and standard recesses 21 b, the resistance it encounters from the other recesses 21 b is greater than the resistance it encounters from the reference recess 21 a.

[0028] That is, the forces F1, F5, and F8 that press against the reference recess 21a as the material of the shaft 4 flows in are smaller than the forces F2 to F4, F6, and F7 that press against the recess 21b. Therefore, when the umbrella-shaped fixing portion 18 is formed, the material of the shaft 4 applies a resultant force F of the forces F1 to F8 to the connecting member 16, pressing the connecting member 16 in the direction opposite to the direction D1. That is, this force F is generated because the force F8 that presses against the reference recess 21a located on the reference line S is small.

[0029] Therefore, when the umbrella-shaped fixing portion 18 is formed, the material of the shaft 4 causes the connecting member 16 to move in the direction of the force F. In other words, the connecting member 16 is slightly displaced by the force F from the correct position where its center coincides with the center of rotation P1 of the shaft 4 in the direction of the force F along the reference line S, and is fixed to the shaft 4.

[0030] In this configuration, when the intake control device 1 is operating, the connecting member 16 can be rotated by the electric motor 7 together with the valve gear 6 within a movable angle θ1 in the opening direction (clockwise as viewed in the drawing) from the fully closed state shown in Figure 3, in which the reference line S forms an angle θ2 with the gear line GL. During this time, the connecting member 16 is moved (displaced) in the direction of the force F, so the center position of the valve gear 6 slightly displaces from the fully closed center position Pc to the fully open center position Po, as shown in Figure 3.

[0031] During this time, as shown in Figure 3, the angle θ2 that the reference line S makes with the gear line GL in the closing direction when the valve is fully closed is less than the movable angle θ1, so the change Δx in the component of the amount of play in the play direction of the connecting member 16 along the gear line GL becomes a maximum value Δx1 when the reference line S coincides with the gear line GL, and becomes a minimum when the center position of the valve gear 6 is at the center position Pc when the valve is fully closed or the center position Po when the valve is fully open.

[0032] In particular, when the angle θ2 that the reference line S makes with the gear line GL when fully closed is half the movable angle θ1, the amount of play (change Δx) in the direction along the gear line GL at the center position Pc and the center position Po matches, and the maximum value Δx1 of the change Δx becomes the minimum.

[0033] In contrast, in the case of the conventional connecting member 16P shown in Figure 4, the reference line S, which is the center C of the area of ​​the region A that overlaps with the umbrella-shaped fixing portion 18 of the shaft mounting hole 17, forms an angle θ2 in the closing direction with respect to the gear line GL when the butterfly valve 5 is fully closed, which is equal to or greater than the movable angle θ1.

[0034] As a result, the center position of the valve gear 6 is displaced significantly in the direction along the gear straight line GL between the center position Pc when fully closed and the center position Po when fully open. Therefore, the maximum value of the change amount Δx of the component of the amount of backlash of the connecting member 16P in the direction along the gear straight line GL becomes a maximum value Δx2 that is significantly larger than the maximum value Δx1 in this embodiment.

[0035] 5 is a graph showing the change in the amount of variation in the center distance relative to the change in the opening degree for this embodiment and a conventional example. The horizontal axis of the graph represents the opening degree, with zero at the fully closed state, and the vertical axis represents the amount of variation Δx (mm) in the center distance, with zero at the fully closed state. The larger the amount of variation Δx, the closer the valve gear gets to the drive gear.

[0036] In the case of this embodiment, the graph curve C1 shows the case where the angle θ2 that the reference line S makes with the gear line GL in the closing direction when the valve is fully closed is approximately 0.5 times the movable angle θ1. In the case of the conventional example, the graph curve C2 shows the case where the angle θ2 that the reference line S makes with the gear line GL in the closing direction when the valve is fully closed is approximately 1.5 times the movable angle θ1.

[0037] From the graph in FIG. 5, it can be seen that the maximum value Δx1 of the amount of variation Δx in the center distance in the present embodiment, shown by the graph curve C1, is significantly smaller than the maximum value Δx2 of the amount of variation Δx in the center distance in the conventional example, shown by the graph curve C2.

[0038] Fig. 6 is a graph showing the rate of change of the center distance obtained by differentiating the graph of Fig. 5. The vertical axis shows the rate of change of the center distance Fr (mm / deg) corresponding to the opening degree on the horizontal axis. Graph curve C3 shows the case of this embodiment, and graph curve C4 shows the case of the conventional example.

[0039] 6, it can be seen that in the case of this embodiment, represented by graph curve C3, the rate of change Fr of the center distance is large when the valve is fully closed and fully open, but is considerably small at intermediate openings which are more frequently used. In contrast, in the case of the conventional example, represented by graph curve C4, the rate of change Fr of the center distance is larger than that of this embodiment in the full opening range from fully closed to fully open.

[0040] As described above, according to this embodiment, when the butterfly valve 5 is in the fully closed state, the angle θ that the reference line S makes with respect to the gear line GL is set to be equal to or smaller than the movable angle θ1 in the direction in which the butterfly valve 5 closes. This makes it possible to suppress fluctuations in the center distance between the valve gear 6 and the drive gear 8 that occur as the valve gear 6 rotates, more than ever before. This makes it possible to improve the wear life of each gear.

[0041] Furthermore, in the fully closed state, the angle θ2 that the reference line S makes with respect to the gear line GL in the closing direction can be set to approximately half the movable angle θ1, thereby minimizing the maximum value Δx1 of the variation amount Δx of the center distance.

[0042] Figure 7 shows a modified connecting member. In the shaft mounting hole 17b of this connecting member 16b, the shape of the reference recess 21c is different from the arc-shaped reference recess 21b of Figure 3. The reference recess 21c has an isosceles triangular shape with a vertex that is trimmed radially outward into a partial circle. In other respects, it has the same configuration as the connecting member 16 of Figure 3.

[0043] 3, the center C of the area of ​​the region A of the shaft mounting hole 17b that overlaps with the umbrella-shaped fixing portion 18 is on the reference line S. Therefore, the direction in which the connecting member 16b is moved by the shaft 4 when the umbrella-shaped fixing portion 18 is formed is along the reference line S, in the direction away from the reference recess 21c located on the reference line S. Therefore, this case also achieves the same effect as the connecting member 16 in FIG.

[0044] Figure 8 shows another modified example of the connecting member. This connecting member 16c has a shape obtained by rotating the shape of the shaft mounting hole 17c of the connecting member 16b in Figure 7 by 180 degrees around the rotation center P1 of the shaft 4. In other respects, it has the same configuration as the connecting member 16b in Figure 7.

[0045] In this case, one of the three reference recesses 21d is located on the reference line S, and therefore, similar to the case of the connecting member 16b in Fig. 7, the center C of the area of ​​the region A that overlaps with the umbrella-shaped fixing portion 18 of the shaft mounting hole 17 is located on the reference line S. However, the center C of the area is located on the opposite side of the rotation center P1 of the shaft 4 from the case in Fig. 4.

[0046] Therefore, in this case too, the connecting member 16c is moved along the reference straight line S in the opposite direction to the center of area C and the center of rotation P1, but since the direction of the force F received from the shaft 4 is opposite to that in the case of the connecting member 16 in Figure 7, the connecting member 16c is moved in the opposite direction to that in the case of the connecting member 16b in Figure 7.

[0047] However, even in this case, the change Δx in the component of the amount of play of the connecting member 16 in the direction along the gear straight line GL reaches a maximum value Dx3 when the reference line S coincides with the gear straight line GL, and reaches a minimum when the center position of the valve gear 6 is located at the center position Pc when fully closed or the center position Po when fully open.

[0048] The amount of variation Δx in the centerline distance and the rate of variation Fr in the centerline distance in this case are shown by graph curves C5 and C6 in Figures 5 and 6. As can be seen from graph curves C5 and C6, the connecting member 16c in Figure 8 also has the same effects as the connecting member 16 in Figure 3 in terms of the amount of variation Δx and the rate of variation Fr.

[0049] Although the embodiment of the present invention has been described above, the present invention is not limited to this. For example, when the butterfly valve 5 is in the fully closed state, the angle θ2 formed by the reference line S in the direction in which the butterfly valve 5 closes with respect to the gear line GL may be the default angle described above, which is an intermediate opening angle smaller than the movable angle θ1.

[0050] This improves the accuracy of the gear pitch (axis-to-axis distance) near the intermediate opening angle, which is the most severe condition for gear wear, thereby suppressing gear wear near the intermediate opening angle.

[0051] 1...intake control device, 2...intake passage, 3...throttle valve, 4...shaft, 5...butterfly valve, 6...valve gear, 7...electric motor, 8...drive gear, 9...fully closed stopper, 10...pinion gear, 11...large gear, 12...small gear, 13...return spring, 14...default spring, 16, 16b, 16c...connecting member, 17...shaft mounting hole, 18...umbrella-shaped fixing portion, 19...circumferential wall, 20...outer periphery, 21a, 21c, 21d...reference recess, 21b...standard recess, A...area, C...area center, C1 to C6...graph curves, GL...gear straight line, P1, P2...rotation center, Pc, Po...center position, S...reference line.

Claims

1. A fluid control device having: a body in which a fluid passage is formed; a plate-shaped valve element rotatably supported by the body via a shaft and opening and closing the fluid passage; and a valve gear fixed to one end of the shaft and rotated by an electric actuator, wherein the valve gear is configured to be rotatable within a rotation angle range of less than 90° corresponding to a fully open state and a fully closed state of the valve element by meshing with a drive gear driven by the electric actuator, the valve gear is provided with a connecting member having a shaft mounting hole through which one end of the shaft is passed, the shaft mounting hole is fixed to one end of the shaft that passes through the shaft mounting hole by an umbrella-shaped fixing portion formed by plastic deformation radially outward of the shaft, the center of an area of ​​a region overlapping the umbrella-shaped fixing portion of the shaft mounting hole when viewed in a direction along the shaft is on a reference line passing through the center of rotation of the shaft, a gear line passing through the center of rotation of the drive gear and the center of rotation of the shaft, and a magnitude of an angle between the reference line and the gear line passing through the center of rotation of the drive gear and the center of rotation of the shaft, when the valve body is in a fully closed state, as viewed in a direction along the shaft, is less than or equal to the movable angle in the direction in which the valve body closes.

2. A fluid control device as described in claim 1, further comprising a default mechanism that maintains the opening of the valve at an intermediate opening angle within the range of movable angles when the driving force from the electric actuator is removed, and wherein in the fully closed state, the angle that the reference line makes with respect to the gear line is approximately equal to the intermediate opening angle.

3. The fluid control device according to claim 1, characterized in that in the fully closed state, the angle that the reference line makes with respect to the gear line is approximately half the movable angle.

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