JP4265070B2 - Butterfly valve shaft - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shaft for operating a butterfly valve, and more particularly to a shaft capable of reducing an increase in sliding resistance with a bearing due to deformation of the shaft.
[0002]
[Prior art]
As a conventional butterfly valve device, one shown in Japanese Utility Model Laid-Open No. 61-6648 having a structure as shown in FIGS. 6 and 7 (referred to as a first prior art) is known.
[0003]
This butterfly valve device will be described with reference to FIGS. 6 and 7. A shaft 5 coupled to each of a plurality of butterfly valves 3 arranged in the passage 2 is connected to the butterfly valve 3 adjacent to the butterfly valve 3. In the middle, they are connected so that they can move relative to each other in the longitudinal direction of the shaft and cannot swing relative to each other, and are provided with spring means 7 that presses the connecting portions 6 against each other. Yes.
[0004]
[Problems to be solved by the invention]
By the way, in the first prior art, the shaft can move in the longitudinal direction, but cannot move in the other direction.
[0005]
For this reason, in the first prior art, the displacement of the position between the outer peripheral surface of the shaft and the inner peripheral surface of the bearing due to the warp or deflection of the shaft is a margin margin (the outer peripheral surface of the shaft and the bearing provided in advance between them). If the clearance is larger than the clearance between the inner peripheral surface and the inner peripheral surface of the shaft, the displacement generated between them cannot be absorbed and the shaft and the bearing cannot be assembled. . Even if the shaft and the bearing are assembled, there is a place where the outer peripheral surface of the shaft is strongly pressed against the inner peripheral surface of the bearing, and the force acting on the part where both abut increases, and the frictional force acting between the two (Sliding resistance) may increase, causing problems such as deterioration of shaft operability. For this reason, shafts and bearings are required to have high dimensional accuracy and assembly accuracy, and manufacturing methods and materials that can guarantee high accuracy are required, which is costly.
[0006]
In recent years, even in a device for attaching such a butterfly valve, which requires high dimensional accuracy and assembly accuracy, conversion of materials and construction methods is progressing for weight reduction and cost reduction. As an example, a butterfly valve and a shaft are integrally formed of a resin material, and a lightweight and inexpensive valve assembly that can be easily assembled is considered. However, since the resin material is likely to warp and bend, the dimensional accuracy is not so good. Therefore, there has been a demand for a shaft structure that can easily cause the above-described problems and can absorb variations in the dimensions and shapes of the shaft.
[0007]
Therefore, the present invention absorbs the variation even when there is a variation larger than the margin between the outer peripheral surface of the shaft and the inner peripheral surface of the bearing due to warpage or deflection of the shaft. Thus, an object of the present invention is to provide a shaft for a butterfly valve that can be easily assembled to the shaft and the bearing and can prevent an increase in sliding resistance between the shaft and the bearing.
[0008]
In order to solve the above-mentioned problem, the technical means taken in the invention of claim 1 is a butterfly valve having a plurality of butterfly valve portions having shaft portions coupled on both sides, and the shaft portion has bearings at both ends. A cylindrical bearing abutting portion having a central axis of the shaft portion as a center is provided and two neutral shafts passing through the central axis are set, and one of the shaft portions is the bearing abutting portion. one second moment about the neutral axis in between, having a first deformation portion which is formed to be larger than the second moment about the other of the neutral axis, the other of the shaft portion, the bearing That is, the second deforming portion is formed between the contact portions so that the second moment of inertia around the other neutral axis is larger than the second moment of inertia around the first neutral axis .
[0009]
According to the above means, is set two neutral axis passing through the center axis of the shank, formed as the second moment around one neutral axis is greater than the second moment about the other neutral axis since having a first deformation portion which is, when to bend the shaft to the other neutral axis direction, easily bend than when to bend the shaft in one neutral axis direction. The shaft in the opposite, to have a second deformation portion which the second moment about the other neutral axis is formed to be larger than the second moment about one of the neutral axis, to one of the neutral axis If the part is to be bent, it also has a part that is easier to bend than if the shaft part is to be bent in the direction of the other neutral axis . Therefore, by inserting the shaft portion of warp or deflection occurs in the bearing, when the force to bend the shaft is applied to the shaft portion, the shaft portion is easily deformed according to the bearing. Further, since there are two directions in which the shaft portion is easily bent (direction in which the moment of inertia of the cross section is reduced), the shaft portion can be bent in any direction depending on the deformation of both.
[0010]
As a result, in the conventional shaft, when a variation more than a margin provided in advance between the outer peripheral surface of the shaft and the inner peripheral surface of the bearing occurs, there is a difference between the outer peripheral surface of the shaft and the inner peripheral surface of the bearing due to the variation. There was a problem that a force to press the two in between acted, increasing the frictional force (sliding resistance) applied between the shaft and the bearing, and the operability of the shaft deteriorated. However, according to the present invention, since the shaft portion can be deformed, this force is consumed to elastically deform the shaft portion , and the force to press both is reduced, so that the frictional force generated by the force is reduced. Reduced . As a result, the butterfly valve can be stably operated.
[0011]
The two neutral axes are preferably provided so as to be orthogonal to each other .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a butterfly valve according to the present invention will be described with reference to the drawings.
[0013]
In FIG. 1, the butterfly valve assembly 10 includes a butterfly valve portion 11, a bearing contact portion 12 a, a first deformation portion 12 b, a second deformation portion 12 c, and a shaft portion 12. On the end face on one side of the butterfly valve portion 11, there is a bearing abutting portion 12a having a cylindrical shape that abuts a bearing (not shown) provided to support the shaft in a swingable manner. In the longitudinal direction of the bearing contact portion 12a, a first deforming portion 12b formed in a rectangle including an arc having the same radius as the shaft portion 12 is provided with a predetermined length and communicates with the shaft portion 12. . The end face of the other side of the butterfly valve part 11 is rotated by 90 degrees around the center axis of the shaft in the same shape as the first deformed part via the bearing contact part 12a in the same manner as the end face of the one side. A second deforming portion 12c formed in a shape is provided with the same predetermined length, communicates with the shaft portion 12 and communicates with the adjacent butterfly valve portion 11. The butterfly valve assembly 10 is integrally formed of a resin material, and the shaft portion 12 and the bearing contact portion 12a have a cylindrical cross-sectional shape.
[0014]
2, FIG. 2 shows a cross section AA of the shaft portion 12 shown in FIG. 1, and shows a cross sectional shape of the shaft , a central axis c thereof, and two neutral axes a and b . The neutral axis a is a line of intersection between a plane passing through the central axis c and a plane orthogonal to the plane passing through the central axis c. Similarly, the neutral axis b is a line of intersection between a plane passing through the central axis c and a plane orthogonal to the plane passing through the central axis c, and the neutral axis a and the neutral axis b are orthogonal to each other. Here, since the bearing contact portion (not shown) is a cylinder, the cross-sectional shape in the direction perpendicular to the central axis c is a circle. As is well known, the secondary moment of inertia about a certain axis in the shaft indicates the difficulty of bending the shaft (the bending strength of the shaft) with respect to a force that attempts to bend the shaft around the shaft. Using this, we will examine which neutral axis is easy to bend when centered. Hereinafter, when examining the difficulty of bending of the shaft using the second moment of section, it is assumed that the length of the shaft in the central axis direction is the same.
[0015]
If the cross-sectional secondary moment around the a-axis of this cross-sectional shape is Ia and the cross-sectional secondary moment Ib around the b-axis, the magnitudes are equal (Ia = Ib). Therefore, it can be understood that the shaft portion (the cross-sectional shape is a circle) is hardly bent in the same direction in either of the neutral axes a and b.
[0016]
FIG. 3 shows a cross section BB of the first deformed portion of FIG. This cross-sectional shape is a rectangle that is parallel to the neutral axis b and in which a circle is cut out by two straight lines whose distance between them is t. The width of the rectangle is t, and the value of t is always smaller than the axis radius r. As described above, a case is considered where moments (forces for bending the axes) around the two neutral axes a and b of the rectangular shape are applied.
[0017]
As described above, since the radius r> the width t of the rectangle, the cross sectional secondary moment Iat around the a axis is compared with the cross sectional secondary moment Ibt around the b axis to satisfy Iat> Ibt.
[0018]
Therefore, the cross-sectional secondary moment around the a-axis (hardness of bending of the shaft against the force that bends the axis around the a-axis) is the cross-sectional secondary moment around the b-axis (centered around the b-axis). Therefore, the first deforming portion is deformed when a moment around the b-axis (force that bends the shaft around the b-axis) is applied. It turns out that it is easy.
[0019]
FIG. 4 shows a cross section CC of the second deformed portion of FIG. This cross-sectional shape is a rectangle in which a circle is cut out by two straight lines parallel to the central axis a and having a distance t between them. Consider a case where moments around two axes of the a-axis and the b-axis shown in FIG.
[0020]
As described above, the axis is configured such that r> t, and when the cross-sectional secondary moment around the a-axis of this axis is Ita and the cross-sectional secondary moment around the b-axis is Itb, the magnitude of the value is Itb> Ita. Thus, it can be seen that the second deformable portion is easily deformed when a moment around the a-axis is applied. Moreover, the relationship of Iat = Itb and Ibt = Ita holds.
[0021]
FIG. 5 is a view showing an assembled state of the butterfly valve assembly of the present invention.
[0022]
The butterfly valve assembly 10 is rotatably supported by a bearing 13 provided in the body 16 and a bearing contact portion 12a. After the butterfly valve assembly 10 is supported by the bearing 13 in the body 16, the fixing member 14 is fixed to the body 15 by the bolt 16, and the butterfly valve assembly 10 and the bearing 13 are held immovably. The body 15 is, for example, an intake device for an internal combustion engine, and the shaft portion 12 of the butterfly valve assembly 10 is rotated by the drive means (not shown) extending in the longitudinal direction of the butterfly valve assembly 10 to open and close the butterfly valve portion 11. The communication of the first outlet 15b of the passage in the body 15 is controlled. When the butterfly valve portion 11 is opened, the passage inlet 15a and the first outlet communicate with each other to form a short passage. When the butterfly valve portion 11 is closed, the second outlet and the passage inlet 15a communicate with each other to form a long passage. As a result, the length of the intake passage can be changed to expand the region where the dynamic effect of intake can be obtained, and the output performance of the internal combustion engine can be improved.
[0023]
From the above, the butterfly valve assembly centering on the a-axis or b-axis is formed by combining the first deformable portion 12b and the second deformable portion 12c having the two cross-sectional shapes into the butterfly valve assembly 10. The butterfly valve assembly 10 has a portion that is more easily deformed than the shaft portion 12 having a cylindrical shape, which is a general shape, with respect to a force for bending 10. In addition, since there are two directions of force that the first deformable portion 12b and the second deformable portion 12c are easily deformed, the butterfly valve assembly 10 can be deformed in all directions.
[0024]
As a result, it is possible to reduce the frictional force (sliding resistance) generated by the force acting between the outer peripheral surface of the bearing contact portion 12a and the inner peripheral surface of the bearing (not shown) and pressing both of them. The valve assembly 10 can be rocked stably.
[0025]
Further, the transmission of the oscillating force performed through the first deformable portion 12b and the second deformable portion 12c connected to the shaft portion 12 is caused by the cross-sectional polar second moments of the first deformable portion 12b and the second deformable portion 12c. If it is set larger than the swinging force that can be applied to the butterfly valve assembly 10, it can be transmitted stably.
[0026]
【The invention's effect】
As described above, according to the first aspect of the present invention, the deformed portion is formed in which the strength (bending strength) of the shaft is small in a specific direction with respect to the force (moment) for bending the shaft in a certain direction. Therefore, the shaft can be elastically deformed according to the bearing and the position of the shaft can be moved. For this reason, the position of the outer peripheral surface of a certain shaft and the position of the inner peripheral surface of a certain bearing have a variation more than a margin provided in advance between them. Even when the inner peripheral surface is pressed and the force acting between them increases, the force acting on the part where the outer peripheral surface of the other shaft and the inner peripheral surface of the other bearing come into contact with each other is almost the same. As described above, the deformed portion whose cross-sectional second moment becomes smaller with respect to the force applied to the shaft is elastically deformed to move the position of the shaft, and the outer peripheral surface of a certain shaft and the inner peripheral surface of a certain bearing The force applied during the period can be relaxed.
[0027]
This force is largely related to the increase or decrease of the frictional force (sliding resistance) acting between the shaft and the bearing that affects the operability of the shaft. As is well known, the frictional force is represented by the product of the coefficient of friction of the surface where the two objects on which the force acts are in contact with the normal force applied between them.
[0028]
When this is applied to the present invention, the friction coefficient is a value determined by the characteristics of the material on the outer peripheral surface of the shaft and the inner peripheral surface of the bearing and the area where the two come into contact. On the other hand, the normal force acting between the two has the same amount as the force acting between the outer peripheral surface of the shaft and the inner peripheral surface of the bearing to press the two (the direction in which the force acts is different). Then, the material properties and the contact area between the two are almost the same between all shafts and bearings, so the force acting between the outer peripheral surface of the shaft and the inner peripheral surface of the bearing is to press both. The increase / decrease of the frictional force (sliding resistance) is determined by the increase / decrease of (vertical drag). Therefore, if this force (vertical drag) decreases, the frictional force (sliding resistance) also decreases.
[0029]
According to the present invention, since the shaft freely moves in accordance with the inner peripheral surface of the bearing, the force (vertical drag) that acts between the shaft and the bearing to press both can be reduced. Therefore, the frictional force (sliding resistance) acting between the shaft and the bearing can be reduced. Conversely, even if either the position of the shaft or the position of the inner peripheral surface of the bearing varies to some extent, the increase in the frictional force (sliding resistance) acting between the two is suppressed, so the operability of the shaft Will not get worse. That is, the high component accuracy and assembly accuracy required in the prior art are not required. As a result, it is not possible to expect high accuracy, but conversion to cheap and lightweight materials and construction methods, for example, the shaft and butterfly valve are made of an integral resin product, or machining of the bearing holding part on the body into which the bearing is inserted is abolished. As a result, the cost can be reduced, which is advantageous.
[0030]
In addition, since the deformable member can be formed integrally with the shaft, it is configured only by a combination of simple shapes, so that the equipment cost such as the mold cost can be reduced, and the productivity at the time of molding with the mold is increased. It is.
[0031]
As described above, even if the outer peripheral surface of the shaft and the inner peripheral surface of the bearing are displaced more than a margin provided in advance between them, an increase in the sliding resistance acting between the two occurs. There is no butterfly valve shaft can be provided.
[Brief description of the drawings]
FIG. 1 is an overall view of a butterfly valve shaft according to the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
3 is a cross-sectional view taken along the line BB in FIG.
4 is a sectional view taken along the line CC in FIG. 1. FIG.
FIG. 5 is a view showing an example of assembly of the butterfly valve shown in FIG. 1;
FIG. 6 is an overall view showing a conventional technique.
FIG. 7 is an enlarged view showing a joint portion of the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Butterfly valve assembly 11 Butterfly valve part 12 Shaft part 12a Bearing contact part 12b 1st deformation part 12c 2nd deformation part 13 Bearing 14 Fixing member 15 Body 15a Path | passage inlet 15b 1st path | pass outlet 15c 2nd path | pass outlet 16 Bolt a, b neutral axis c central axis r axial radius t rectangular width

Claims (2)

In the butterfly valve having a plurality of butterfly valve portions having shaft portions coupled on both sides ,
The shaft portion has a cylindrical bearing contact portion that is in contact with the bearing at both ends and has the center axis of the shaft portion as an axis, and two neutral shafts passing through the center axis are set.
One of the shaft portions is a first deformed portion formed such that a cross-sectional secondary moment around one neutral axis is greater than a cross-sectional secondary moment around the other neutral axis between the bearing contact portions. Have
The other of the shaft portions is a second deforming portion formed such that a cross-sectional secondary moment around the other neutral axis is greater than a cross-sectional secondary moment around the one neutral shaft between the bearing contact portions. A butterfly valve characterized by having . The butterfly valve according to claim 1, wherein the two neutral shafts are provided to be orthogonal to each other .

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