Coupling structure

Abstract

To allow for easy control of the tightening strength of the two cover components. [Solution] In a coupling structure comprising a pair of locking bodies 2a, 3a provided on two shafts 2, 3 whose shaft ends face each other, an endless rotary transmission body 10 that meshes with the teeth of the pair of locking bodies 2a, 3a, a plurality of cover members 20A, 20B that cover the entire meshing portion between the locking bodies 2a, 3a and the rotary transmission body 10, a spacing member 40 positioned between the opposing contact surfaces 24, 24 of the cover members 20A, 20B, and a bolt 30 for fastening the cover members 20A, 20B together, the structure is configured to include a spacing holding part that restricts the distance between the contact surfaces 24, 24 that contact the spacing member 40 so that it does not fall below a predetermined value when the bolt 30 is fastened.

Description

Technical Field

[0001] This invention relates to a coupling structure.

Background Art

[0002] A coupling is used to connect the ends of a pair of shafts. A chain coupling is a type of coupling, and is composed of a locking body such as a sprocket having teeth fixed to each shaft and arranged in parallel along the circumferential direction, and an endless chain having two rows of engaging portions corresponding to the teeth of the sprockets of both shafts.

[0003] The chain transmits rotation from the driving shaft to the driven shaft through two sprockets. At this time, due to the play at the meshing portion between the chain and the sprocket, rotation is transmitted while allowing misalignment of the axial centers of both shafts, bending between the axial centers, deflection, etc. (see, for example, Patent Document 1).

[0004] In the above-described coupling, a cover that covers the entire meshing portion between the chain and the sprocket is provided. The cover is composed of two split cover members. The cover member includes a cylindrical portion having a semi-cylindrical shape, and end wall portions protruding in the inner diameter direction from both ends in the cylindrical axis direction of the cylindrical portion. Further, a flat contact surface is provided at a portion where the two cover members face each other among the cylindrical portion and the end wall portions.

[0005] Two cover members facing each other across the shaft cover the meshing portion of the coupling from its outer periphery, and hold a lubricant such as grease in the sealed space inside the cover member. The end wall portion includes, at its inner diameter side edge, an arcuate seal portion along the outer periphery of one shaft and an arcuate seal portion along the outer periphery of the other shaft. The two seal portions each have a concave groove facing the inner diameter side at a portion along the outer periphery of the shaft of the end wall portion, and an annular seal ring fitted to the outer periphery of the shaft is accommodated in the concave groove. The seal ring is an annular member made of an elastic material such as rubber, for example, an O-ring.

[0006] Furthermore, the contact surfaces of the opposing cover members are fastened together with bolts to ensure they are in close contact. A plate-shaped gap member made of an elastic material such as cork or resin is placed between the contact surfaces. This gap member prevents the cover members from directly touching each other and also functions as a packing to prevent the internal lubricant from leaking out. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 5728121 [Overview of the project] [Problems that the invention aims to solve]

[0008] In this type of coupling structure, the degree of tightening when fastening opposing cover members together becomes a problem. In conventional chain coupling structures, when the cover members are fastened together with bolts, the contact surfaces move closer together, compressing the spacing member, until it reaches its compression limit. If the contact surfaces get too close together, the spacing member may contract excessively, preventing it from performing its intended cushioning function. Conversely, if the tightening is too weak, the contact between the spacing member and the contact surface will be weak, preventing the packing from performing its intended sealing function.

[0009] Therefore, the objective of this invention is to make it possible to easily control the tightening strength of the two cover members that sandwich the spacing member. [Means for solving the problem]

[0010] To solve the above problems, this invention employs a coupling structure comprising two shafts with their shaft ends facing each other, a pair of locking bodies provided on each of the two shafts and having a plurality of teeth arranged in parallel along the direction of the axis, an endless rotary transmission body having two rows of engaging portions that mesh with the teeth of the pair of locking bodies, a plurality of cover members that cover the entire meshing portion between the locking bodies and the rotary transmission body, a spacing member disposed between the opposing contact surfaces of the cover members, and a bolt for tightening the cover members together with the spacing member sandwiched between the contact surfaces, wherein the coupling structure is provided with a spacing holding portion that restricts the distance between the contact surfaces that contact the spacing member to not fall below a predetermined value when tightened with the bolt (Configuration 1).

[0011] The spacing-holding portion employs a coupling structure in which a protrusion is provided on one of the opposing contact surfaces and a recess is provided on the other surface into which the protrusion fits, with the top of the protrusion contacting the bottom of the recess (Configuration 2).

[0012] The spacing-holding portion employs a coupling structure in which a convex portion is provided on one of the opposing contact surfaces and a recess provided on the other surface into which the convex portion fits, and an outer tapered portion formed on the edge of the convex portion abuts against an inner tapered portion formed on the edge of the recess (Configuration 3).

[0013] In any one of configurations 1 to 3, the spacing-holding portion can be provided around the entire circumference of the bolt's axis (configuration 4).

[0014] In any one of configurations 1 to 3, the spacing member can be provided between one bolt and another bolt (configuration 5). [Effects of the Invention]

[0015] This invention makes it possible to easily control the tightening strength of the two cover members that sandwich the spacing member. [Brief explanation of the drawing]

[0016] [Figure 1] Vertical cross-sectional view showing the fixing structure of the coupling cover according to an embodiment of the present invention [Figure 2] Cross-sectional view taken along line II-II of FIG. 1 [Figure 3] Cross-sectional view taken along line III-III of FIG. 1 [Figure 4] Side view showing the cover for chain coupling [Figure 5] Cross-sectional view taken along line V-V of FIG. 4 [Figure 6] Cross-sectional view taken along line VI-VI of FIG. 4 [Figure 7] Plan view showing the chain for chain coupling [Figure 8] Front view of FIG. 7 [Figure 9] Front view showing a state where two cover members constituting the coupling cover are opposed to each other via a spacer [[ID= 27]] [Figure 10] Plan view of FIG. 9 [Figure 11] Left side view of FIG. 9 [Figure 12] Exploded view of FIG. 9 [Figure 13] Plan view of the spacer [Figure 14] Exploded perspective view of the coupling cover [Figure 15] Enlarged cross-sectional view of the main part showing a modified example [Figure 16] Enlarged cross-sectional view of the main part showing a modified example [Figure 17] Enlarged cross-sectional view of the main part showing a further modified example

Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described based on the drawings. The coupling structure of this embodiment is for connecting the ends of two shafts 2 and 3 whose shaft ends face each other, and is fixed to each of the shafts 2 and 3 and has a pair of sprockets (locking bodies) 2a and 3a provided with a plurality of teeth arranged in parallel along the circumferential direction of the shaft, and an endless chain (rotary transmission body) 10 having two rows of engaging portions corresponding to the teeth of the sprockets 2a and 3a of both shafts 2 and 3. It is a chain coupling equipped with

[0018] The chain 10 is connected such that two rows of engaging parts are integrated, and it transmits rotation from the driving shaft 2 to the driven shaft 3 through the two sprockets 2a and 3a. At this time, the play in the meshing parts between the sprockets 2a and 3a and the chain 10 allows for misalignment of the axes of both shafts 2 and 3, as well as bending and deflection of the axes, while still transmitting rotation.

[0019] In Figure 1, the sprockets 2a, 3a and shafts 2, 3 are shown as a single integrated component, but it is generally the case that the sprockets 2a, 3a and the bodies of shafts 2, 3 are composed of separate components. For example, as in Patent Document 1, a structure can be adopted in which shafts 2, 3 are inserted into bosses provided in the center of the sprockets 2a, 3a, and the sprockets 2a, 3a and the bodies of shafts 2, 3 are fixed together with screws or the like. Shaft 2 and sprocket 2a, and shaft 3 and sprocket 3a are fixed so that they cannot move relative to each other in the axial direction and around the axis. These pairs of sprockets 2a, 3a have the same shape and size, and their circumferential pitch is also the same.

[0020] As shown in Figures 1, 7, and 8, the chain 10 is a two-row metal roller chain. In this chain 10, two outer plates 11, 11 and one intermediate plate 13 are fitted to one pin 14. In addition, inner plates 12, 12 are fitted to the outer circumference of the pin 14 via bushings 17. Two inner plates 12 are positioned between one outer plate 11 and the intermediate plate 13, and two between the other outer plate 11 and the intermediate plate 13. Furthermore, rotatable rollers 15 are fitted onto the outer circumference of the bushings 17.

[0021] One outer plate 11 and the inner plate 12 adjacent to it are arranged alternately in a staggered pattern (inside and out) along the length of the chain 10. The other outer plate 11 and the inner plate 12 adjacent to it are also arranged alternately in a staggered pattern (inside and out) along the length of the chain 10. On both the front and back sides of the intermediate plate 13, the inner plates 12 are arranged alternately in a staggered pattern (inside and out) along the length. The inner plates 12 on both the front and back sides of the intermediate plate 13 are positioned at the same position relative to the length of the chain 10. Therefore, focusing on a single pin 14, the arrangement is as follows: one outer plate 11, inner plate 12, roller 15, inner plate 12, intermediate plate 13, inner plate 12, roller 15, inner plate 12, and the other outer plate 11. In other words, this chain 10 is a double chain equipped with two rollers 15 in parallel in the width direction.

[0022] The teeth of each sprocket 2a, 3a engage with the two rows of rollers 15, that is, the engagement portion formed by the spaces between adjacent pins 14, 14 of the chain 10 and between inner plates 12, 12 engages, thereby transmitting rotational torque from the driving shaft 2 to the driven shaft 3.

[0023] Furthermore, this coupling structure is equipped with a chain sprocket cover 20 (hereinafter simply referred to as cover 20) which uses two split cover members 20A and 20B that cover the entire meshing portion between the sprockets 2a and 3a and the chain 10.

[0024] As shown in Figures 1 and 2, the cover members 20A and 20B each have a semi-cylindrical cylindrical portion 31 and end wall portions 32 that protrude inward from both ends of the cylindrical portion 31 in the axial direction. The portions of the cylindrical portion 31 and the end wall portions 32 where the cover members 20A and 20B face each other are provided with flat contact surfaces 24. The internal space enclosed by the cylindrical portion 31 and the end wall portions 32 is the space that accommodates the entire meshing portion between the sprockets 2a and 3a and the chain 10. In other words, the two-part cover members 20A and 20B cover the entire meshing portion between the sprockets 2a and 3a and the chain 10.

[0025] As shown in Figure 4, the contact surface 24 includes a parallel portion 24a extending parallel to the axes 2 and 3 and of equal width along the edge of the cylindrical portion 31, a rising portion 24b rising in the radial direction along the end wall portion 32, and a corner portion 24c between the parallel portion 24a and the rising portion 24b. Bolt holes 26 and 27 through which the bolts 30 are inserted are opened in the corner portion 24c.

[0026] The end wall portion 32 is provided with a groove 28 on its inner diameter side edge for accommodating an annular seal ring 4 (see Figure 1) that runs along the outer circumference of the shafts 2 and 3. The groove 28 has a V-shaped cross-section over its entire circumference and slopes from the bottom in the width direction center toward both edges in the width direction, gradually becoming shallower. The rising portion 24b of the contact surface 24 has its inner diameter side edge facing the groove 28, and the shape of its inner diameter side edge is the same V-shaped cross-section as the groove 28. In addition to the V-shaped cross-section of this embodiment, the groove 28 can also have an arc-shaped or U-shaped cross-section.

[0027] As shown in Figures 2 and 3, the opposing contact surfaces 24 are fixed in close contact with each other via a plate-shaped spacing member 40. At this time, the cover members 20A and 20B that sandwich the shafts 2 and 3 are tightened and fixed in a direction that brings the contact surfaces 24 into close contact with each other by bolts 30 inserted through bolt holes 26 and 27 that open in the corner portion 24c.

[0028] One cover member 20A has two bolt holes 26, which are through holes without threads, on the upper side of the shafts 2 and 3 in Figure 4, and two bolt holes 27, which have internal threads, on the lower side. Similarly, the other cover member 20B also has two bolt holes 26, which are through holes without threads, and two bolt holes 27, which have internal threads, just like the first cover member 20A.

[0029] As shown in Figures 9 to 12, one cover member 20A and the other cover member 20B are common parts, and they are arranged upside down so that the bolt hole 27 faces the bolt hole 26. As a result, the threaded portion 30b of the bolt 30 passes through the bolt hole 26 and is screwed into the bolt hole 27. The head 30a of the bolt 30 is housed in a concave cutout 23 provided in the cylindrical portion 31, so as not to protrude outward from the circular outer shape of the cover 20 (see Figure 2). In addition, the head 30a of the bolt 30 is provided with a concave operating portion 30c having a non-circular cross-section (hexagonal cross-section in this embodiment), so that the bolt 30 can be tightened and loosened by inserting a tool into the operating portion 30c.

[0030] One cover member 20A and the other cover member 20B are fastened together, and the opposing contact surfaces 24, 24 of the cover members 20A and 20B are tightly sealed together via a spacing member (packing / gasket) 40 placed between them, ensuring a liquid-tight state at the contact point. In other words, the cover members 20A and 20B are fastened together by bolts 30 with the spacing member 40 sandwiched between the contact surfaces 24, 24. At the same time, the seal ring (O-ring) 4 in the groove 28 seals to prevent lubricating oil from leaking out from between the outer circumference of the shafts 2 and 3 and the sealing portion of the inner diameter side edge of the end wall portion 32.

[0031] The seal ring 4 uses a rubber annular member, but its material is not limited to rubber; a resin seal ring 4 may also be used.

[0032] Cork material, which has high heat resistance, is used as the material for the spacing member 40. The spacing member 40 is a plate-like member of the same shape, having an outer edge that almost perfectly overlaps with the outer edge of the contact surface 24 shown in Figure 4. That is, as shown in Figure 13, it has a parallel portion 40a that extends parallel to the axes 2 and 3 and of equal width along the end edge of the cylindrical portion 31, a rising portion 40b that rises in the inner diameter direction along the end wall portion 32, and a corner portion 40c at the connection point between the parallel portion 40a and the rising portion 40b. A hole 40d for inserting a bolt is provided in the corner portion 40c. In addition, the shape of the inner diameter side end edge of the rising portion 40b is V-shaped, the same shape as the groove 28. Figure 14 is an exploded perspective view that shows the positional relationship between the two spacing members 40 and the cover members 20A and 20B on both sides.

[0033] Various materials can be used for the spacing member 40, which have elasticity and can maintain the sealing properties of the joint. Typically, as in this embodiment, cork material with heat resistance of 200°C or higher is used, but other materials such as paper, nonwoven fabric, or other materials can be used depending on the usage conditions of the coupling.

[0034] In the coupling structure of this invention, the cover 20 is provided with a spacing holding portion that restricts the distance between the contact surfaces 24, 24 that contact the spacing member 40 so as not to fall below a predetermined value when tightened with bolts 30.

[0035] The spacing member of this embodiment consists of a protrusion 21 provided on one of the opposing contact surfaces 24, 24 and a recess 22 provided on the other surface into which the protrusion 21 fits. As shown in Figure 5, the height L2 of the protrusion 21 from the contact surface 24 is greater than the depth L1 of the recess 22 from the contact surface 24. Therefore, when tightening the opposing cover members 20A and 20B together, the spacing member 40 and the contact surfaces 24 do not come into excessive contact, maintaining appropriate pressure and preventing the spacing member 40 from hindering the cushioning and sealing functions.

[0036] In this embodiment, the top (top surface) 21a of the protruding side of the convex portion 21 and the bottom (bottom surface) 22a of the recessed portion 22 are both made of flat surfaces, and their entire surfaces are in contact with each other. If, for example, at least one of the top (top) 21a of the protruding side of the convex portion 21 and the bottom (bottom) 22a of the recessed portion 22 is not a flat surface, then the protruding height L2 of the convex portion 21 and the depth L1 of the recessed portion 22 referred to here mean the protruding height L2 of the convex portion 21 from the contact surface 24 and the depth L1 of the recessed portion 22 from the contact surface 24 at the position where the top (top) 21a of the protruding side of the convex portion 21 and the bottom (bottom) 22a of the recessed portion 22 first come into contact when the opposing cover members 20A and 20B are brought close together and the convex portion 21 enters the recessed portion 22.

[0037] Here, if we define the thickness of the spacing member 40 before tightening (before use) as t0, and the thickness under appropriate pressure as t1, L2-L1=t1...(Formula 1) It is desirable to do so. If an error α is allowed, t1+α>L2-L1>t1-α (Formula 2) That is. Also, t0>L2-L1...(Formula 3) It is required that this be the case.

[0038] In this way, by providing a spacing retention section on the cover 20, excessive or insufficient tightening is eliminated, making it easy to control the tightening strength of the two cover members 20A and 20B that sandwich the spacing member 40.

[0039] In this embodiment, the spacing-holding portion is provided around the entire circumference of the bolt 30. Specifically, the convex portion 21 and concave portion 22 constituting the spacing-holding portion are provided around the bolt holes 26 and 27 of the cover members 20A and 20B, respectively. This makes it easier to ensure an appropriate pressing force on the spacing member 40 around the bolt 30, where excessive tightening is likely to occur. In particular, in this embodiment, the convex portion 21 and concave portion 22 have a circular cross-section, and the centers of the circular convex portion 21 and concave portion 22 lie on the axis of the bolt 30 (the axis of the bolt holes 26 and 27), thus further ensuring an appropriate pressing force around the bolt 30.

[0040] In this embodiment, the spacing portion is provided around the entire circumference of the bolt 30's axis, but the position of this spacing portion is not limited to this embodiment. For example, the spacing portion may be provided at a position away from the bolt 30. That is, the spacing portion may be provided at a position away from the bolt holes 26 and 27, for example, between one bolt 30 (one bolt hole 26) and another bolt 30 (another bolt hole 26), or between one bolt 30 (one bolt hole 27) and another bolt 30 (another bolt hole 27).

[0041] Modified versions of the spacing-holding portion are shown in Figures 15 and 16. In these modified versions, as in the above embodiment, the top 21a of the convex portion 21 does not contact the bottom 22a of the concave portion 22, and the outer tapered portion 21b formed on the edge of the convex portion 21 contacts the inner tapered portion 22b formed on the edge of the concave portion 22. In the embodiment, the outer tapered portion 21b is provided around the entire circumference of the edge of the convex portion 21, and the inner tapered portion 22b is provided around the entire circumference of the edge of the concave portion 22, but these may be made as part of their respective edges.

[0042] The outer tapered portion 21b and the inner tapered portion 22b make surface contact, facilitating alignment between opposing cover members 20A and 20B. The effects of providing a spacing-holding portion, such as preventing excessive tightening, preventing insufficient tightening, and facilitating control of tightening strength, are the same as in the previously described embodiment.

[0043] In the modified configuration shown in Figures 15 and 16, when the outer tapered portion 21b and the inner tapered portion 22b are in surface contact and can no longer be tightened, the top 21a of the convex portion 21 does not come into contact with the bottom 22a of the concave portion 22. In this configuration, the protrusion height L2 of the convex portion 21 from the contact surface 24 and the depth L1 of the concave portion 22 from the contact surface 24 can be freely set.

[0044] Furthermore, in the further modification shown in Figure 17, the outer tapered portion 21b formed on the edge of the convex portion 21 abuts against the inner tapered portion 22b formed on the edge of the concave portion 22, and when a predetermined degree of tightening is reached, the top portion 21a of the convex portion 21 abuts against the bottom portion 22a of the concave portion 22. In this case as well, if the thickness of the spacing member 40 under appropriate pressure is t1, an error α is allowed, t1+α>L2-L1>t1-α (Formula 2) It is required that this be the case.

[0045] In the modified example shown in Figure 17, the shapes of the outer tapered portion 21b and the inner tapered portion 22b are the same as those in the modified examples shown in Figures 15 and 16.

[0046] In the embodiments described above, the cover members 20A and 20B are composed of members of the same shape and size, but this does not preclude them from having different shapes and sizes. Although the cover 20 is composed of two cover members 20A and 20B, the cover 20 may also be composed of three or more cover members 20A, 20B, 20C, etc.

[0047] In conventional coupling structures, excessive tightening of opposing cover members 20A and 20B could cause the spacing member 40 to shrink excessively, or conversely, insufficient tightening could prevent it from performing its intended sealing function. However, this invention includes a spacing-holding section that regulates the distance between the contact surfaces 24, 24 that contact the spacing member 40 so that it does not fall below a predetermined value, thus allowing for easy control of the tightening strength. In other words, it is easy to control the thickness and degree of contact of the spacing member (packing / gasket) 40 after tightening.

[0048] Furthermore, conventional coupling structures have the problem of difficulty in aligning opposing cover members 20A and 20B when tightening them together. Conventionally, alignment was performed by feel and visual inspection, using the clearance between the outer circumference of the tightening bolt and the inner surface of the mounting hole as a guide. However, with this invention, the convex portion 21 of the opposing cover members 20A and 20B fits into the concave portion 22, making alignment easy, thus reducing the time and effort required for the work and improving the accuracy of the finished product. [Explanation of symbols]

[0049] 1 Chain Coupling 2,3 axes 2a, 3a Sprocket (locking body) 4 O-rings (seal rings) 10 Chains (rotating transmission units) 20 Chain sprocket cover 20A, 20B Cover component 21 Convex part 22 recess 24 Contact surface part 30 volts 31 Cylindrical part 32 End wall section 40 Spacing members

Claims

1. In a coupling structure comprising: two shafts (2, 3) with their shaft ends facing each other; a pair of locking bodies (2a, 3a) provided on each of the two shafts (2, 3) and having a plurality of teeth arranged in parallel along the direction of the shaft; an endless rotary transmission body (10) having two rows of engaging portions that mesh with the teeth of the pair of locking bodies (2a, 3a); a plurality of cover members (20A, 20B) that cover the entire meshing portion between the locking bodies (2a, 3a) and the rotary transmission body (10); a spacing member (40) positioned between the opposing contact surfaces (24) of the cover members (20A, 20B); and a bolt (30) that fastens the cover members (20A, 20B) together with the spacing member (40) sandwiched between the contact surfaces (24, 24), A coupling structure comprising a spacing-holding part that restricts the distance between the contact surfaces (24, 24) that contact the spacing member (40) to not fall below a predetermined value when tightened by the bolt (30).

2. The coupling structure according to claim 1, wherein the spacing holding portion comprises a convex portion (21) provided on one of the opposing contact surfaces (24, 24) and a recess (22) provided on the other surface into which the convex portion (21) fits, and the top portion (21a) of the convex portion (21) contacts the bottom portion (22a) of the recess (22).

3. The coupling structure according to claim 1, wherein the spacing-holding portion comprises a convex portion (21) provided on one of the opposing contact surfaces (24, 24) and a recess (22) provided on the other surface into which the convex portion (21) fits, and an outer tapered portion (21b) formed on the edge of the convex portion (21) contacts an inner tapered portion (22b) formed on the edge of the recess (22).

4. The coupling structure according to any one of claims 1 to 3, wherein the spacing holding portion is provided around the entire circumference of the bolt (30) axis.

5. The coupling structure according to any one of claims 1 to 3, wherein the spacing holding portion is provided between one of the bolts (30) and the other bolt (30).

Images