Coupling Structure

Abstract

To easily manage the fastening strength of two cover members. [Solution] The coupling structure includes 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 arranged between the opposing abutment surfaces 24, 24 of the cover members 20A, 20B, and a bolt 30 that fastens the cover members 20A, 20B together, and is configured to include a spacing retaining section that, when fastened by the bolt 30, regulates the distance between the abutment surfaces 24, 24 that contact the spacing member 40 so that it does not fall below a predetermined value.

Description

[Technical Field]

[0001] The present invention relates to a coupling structure. [Background technology]

[0002] Couplings are used to connect the ends of a pair of shafts. A chain coupling is a type of coupling that consists of a locking body, such as a sprocket, fixed to each shaft and having parallel teeth along the circumferential direction, and an endless chain with two rows of engaging portions that correspond to the teeth of the sprockets on both shafts.

[0003] The chain transmits rotation from the driving shaft to the driven shaft through two sprockets. At this time, the play at the meshing points between the chain and sprockets allows for misalignment of the shafts, bending, and deflection between the shafts, while transmitting the rotation (see, for example, Patent Document 1).

[0004] The coupling is provided with a cover that covers the entire meshing portion between the chain and the sprocket. The cover is composed of two split cover members. The cover member has a semi-cylindrical tubular portion and end wall portions that protrude radially inward from both ends of the tubular portion in the axial direction. Furthermore, the tubular portion and the end wall portions have flat abutment surfaces at the portions where the two cover members face each other.

[0005] Two cover members facing each other across the shaft cover the outer periphery of the mating portion of the coupling and hold a lubricant such as grease in the sealed space inside the cover members. The end wall portion has, on its inner diameter side edge, an arc-shaped seal portion that follows the outer periphery of one shaft, and an arc-shaped seal portion that follows the outer periphery of the other shaft. Each of the two seal portions has a groove facing the inner diameter in the part of the end wall portion that follows the outer periphery of the shaft, and an annular seal ring that fits around the outer periphery of the shaft is housed in the groove. The seal ring is, for example, an O-ring or other annular member made of a resilient material such as rubber.

[0006] The contact surfaces of the opposing cover members are fastened together with bolts to ensure close contact. A plate-shaped spacing member made of an elastic material such as cork or resin is sandwiched between the contact surfaces. This spacing member prevents the cover members from coming into direct contact with 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 Summary of the Invention [Problem to be solved by the invention]

[0008] In this type of coupling structure, the degree of tightening when tightening the opposing cover members becomes an issue. In conventional chain coupling structures, when the cover members are tightened together with bolts, the abutting surfaces approach each other until they reach their compression limit, compressing the spacing member. If the abutting surfaces approach each other too closely, the spacing member may contract excessively, preventing it from performing its intended cushioning function. Conversely, if the tightening is too weak, the spacing member and the abutting surfaces may not adhere well together, preventing the packing from performing its intended sealing function.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to make it possible to easily manage the tightening strength of the two cover members that sandwich the spacing member. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention provides a coupling structure including two shafts with opposing shaft ends, a pair of locking bodies provided on each of the two shafts and having a plurality of teeth arranged in parallel around the axis, an endless rotary power 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 power transmission body, a spacing member placed between the opposing abutment surfaces of the cover members, and a bolt that fastens the cover members together with the spacing member sandwiched between the abutment surfaces, the coupling structure including a spacing retaining portion that restricts the distance between the abutment surfaces that come into contact with the spacing member so that it does not become less than a predetermined value when fastened with the bolt (Configuration 1).

[0011] The spacing portion is a convex portion provided on one of the opposing contact surfaces and a concave portion provided on the other surface into which the convex portion fits, and a coupling structure is adopted in which the top of the convex portion abuts against the bottom of the concave portion (Configuration 2).

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

[0013] In any one of the configurations 1 to 3, the spacing portion may be provided around the entire periphery of the bolt axis (configuration 4).

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

[0015] This invention makes it possible to easily manage the fastening strength of the two cover members sandwiching the spacing member. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a longitudinal sectional view showing a fixing structure for a coupling cover according to an embodiment of the present invention; [Figure 2] II-II cross section of Figure 1 [Figure 3] III-III cross section of Figure 1 [Figure 4] Side view showing the chain coupling cover [Figure 5] VV cross section of Figure 4 [Figure 6] VI-VI cross section of Figure 4 [Figure 7] Plan view showing a chain for a chain coupling [Figure 8] Front view of Figure 7 [Figure 9] FIG. 1 is a front view showing a state in which two cover members constituting a coupling cover are opposed to each other via a spacing member; [Figure 10] Plan view of Figure 9 [Figure 11] Left side view of Figure 9 [Figure 12] Exploded view of Figure 9 [Figure 13] Plan view of spacing member [Figure 14] Exploded perspective view of the coupling cover [Figure 15] Enlarged cross-sectional view of a main part showing a modified example [Figure 16] Enlarged cross-sectional view of a main part showing a modified example [Figure 17] FIG. 10 is an enlarged cross-sectional view of a main part showing a further modified example. DETAILED DESCRIPTION OF THE INVENTION

[0017] An embodiment of the present invention will be described below with reference to the drawings. The coupling structure of this embodiment is a chain coupling that connects the ends of two shafts 2 and 3, whose shaft ends face each other, and includes a pair of sprockets (locking bodies) 2a and 3a that are fixed to the shafts 2 and 3 and have a plurality of teeth arranged in parallel around the shafts, and an endless chain (rotary power transmission body) 10 that has two rows of engaging portions that correspond to the teeth of the sprockets 2a and 3a on both shafts 2 and 3.

[0018] The chain 10 is connected so that two rows of engaging portions are integrated, and transmits rotation from the driving shaft 2 to the driven shaft 3 through two sprockets 2a, 3a. At this time, the play at the meshing portions between the sprockets 2a, 3a and the chain 10 allows for misalignment of the shafts 2, 3, as well as bending and deflection between the shafts.

[0019] In Figure 1, the sprockets 2a, 3a and the shafts 2, 3 are shown as a single unit, but the sprockets 2a, 3a and the shafts 2, 3 are generally separate components. For example, as in Patent Document 1, a structure can be adopted in which the shafts 2, 3 are inserted into bosses provided at the centers of the sprockets 2a, 3a, and the sprockets 2a, 3a are then fixed to the shafts 2, 3 with screws or the like. The shaft 2 and sprocket 2a, and the shaft 3 and sprocket 3a are fixed so that they cannot move relative to each other in the axial direction or around the axis. The pair of sprockets 2a, 3a have the same shape and size, and also have the same circumferential pitch.

[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. Inner plates 12, 12 are fitted to the outer periphery of the pin 14 via bushings 17. Two inner plates 12 are arranged between one outer plate 11 and the intermediate plate 13, and two inner plates 12 are arranged between the other outer plate 11 and the intermediate plate 13. Furthermore, rotatable rollers 15 are fitted onto the outer periphery of the bushings 17.

[0021] One outer plate 11 and the inner plate 12 located along it are alternately arranged in a staggered pattern (inside and outside) along the length of the chain 10. The other outer plate 11 and the inner plate 12 located along it are alternately arranged in a staggered pattern (inside and outside) along the length of the chain 10. The inner plates 12 are alternately arranged in a staggered pattern (inside and outside) on both the front and back sides of the intermediate plate 13 along the length. The inner plates 12 on both the front and back sides of the intermediate plate 13 are positioned in the same position relative to each other in the length of the chain 10. Therefore, when focusing on one pin 14, the order of arrangement is 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 with two rollers 15 arranged side by side in the width direction.

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

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

[0024] 1 and 2, the cover members 20A, 20B include a semi-cylindrical tubular portion 31 and end wall portions 32 that protrude radially inward from both ends of the tubular portion 31 in the axial direction. The tubular portion 31 and the end wall portions 32 are provided with flat abutment surfaces 24 at the portions where the cover members 20A, 20B face each other. The internal space surrounded by the tubular portion 31 and the end wall portions 32 accommodates the entire meshing portion between the sprockets 2a, 3a and the chain 10. In other words, the two-split cover members 20A, 20B cover the entire meshing portion between the sprockets 2a, 3a and the chain 10.

[0025] 4, the abutment surface 24 includes a parallel portion 24a extending parallel to the axes 2 and 3 and of equal width along the end edge of the cylindrical portion 31, a rising portion 24b rising in the radially inward 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 bolt 30 is inserted, are formed in the corner portion 24c.

[0026] The end wall portion 32 is provided on its inner diameter side edge with a recessed groove 28 that accommodates an annular seal ring 4 (see FIG. 1) that fits along the outer periphery of the shafts 2, 3. The recessed groove 28 has a V-shaped cross section around the entire circumference, and is shaped to gradually become shallower from its bottom at the center in the width direction toward both widthwise ends. The rising portion 24b of the abutment surface 24 has an inner diameter side edge that faces the recessed groove 28, and the shape of the inner diameter side edge is the same V-shaped cross section as the recessed groove 28. Note that the shape of the recessed groove 28 may be an arc-shaped cross section or a U-shaped cross section in addition to the V-shaped cross section of the embodiment.

[0027] 2 and 3, the opposing contact surfaces 24 are fixed in a state of close contact with each other via a plate-shaped spacing member 40. At this time, the cover members 20A and 20B sandwiching the shafts 2 and 3 are fastened in a direction in which the contact surfaces 24 come into close contact with each other by bolts 30 inserted through bolt holes 26 and 27 opening in the corner portions 24c.

[0028] One cover member 20A has two bolt holes 26 configured as through holes without threads on the upper side and two bolt holes 27 with internal threads on the lower side, sandwiching the axes 2 and 3 in Fig. 4. Similarly to one cover member 20A, the other cover member 20B also has two bolt holes 26 configured as through holes without threads and two bolt holes 27 with internal threads.

[0029] As shown in FIGS. 9 to 12, one cover member 20A and the other cover member 20B are common components, and are arranged upside down so that bolt hole 27 faces bolt hole 26. As a result, threaded portion 30b of bolt 30 passes through bolt hole 26 and is screwed into bolt hole 27. Head 30a of bolt 30 is housed in recessed lightening portion 23 provided in tubular portion 31 and does not protrude outward from the circular outline of cover 20 (see FIG. 2). In addition, head 30a of bolt 30 is provided with recessed operating portion 30c having a non-circular cross section (a hexagonal cross section in this embodiment), and bolt 30 can be tightened or loosened by inserting a tool into operating portion 30c.

[0030] When one cover member 20A and the other cover member 20B are fastened together, the opposing abutment surfaces 24, 24 of the cover members 20A, 20B are tightly attached via a spacing member (packing / gasket) 40 disposed therebetween, ensuring a liquid-tight state at the tightly attached portion. That is, the cover members 20A, 20B are fastened together by the bolts 30 with the spacing member 40 sandwiched between the abutment surfaces 24, 24. At the same time, the seal ring (O-ring) 4 in the recessed groove 28 seals between the outer peripheries of the shafts 2, 3 and the seal portion on the inner diameter side edge of the end wall portion 32 to prevent lubricating oil from leaking out.

[0031] A rubber annular member is used for the seal ring 4, but the material is not limited to rubber, and a resin seal ring 4 may also be used.

[0032] The spacing member 40 is made of cork, which has high heat resistance. The spacing member 40 is a plate-like member with an outer edge that almost perfectly overlaps the outer edge of the abutment surface 24 shown in FIG. 4. Specifically, as shown in FIG. 13, the spacing member 40 includes a parallel portion 40a extending along the end edge of the tubular portion 31, parallel to the axes 2 and 3, and having the same width; a rising portion 40b rising radially inward along the end wall portion 32; and a corner portion 40c at the junction between the parallel portion 40a and the rising portion 40b. A bolt insertion hole 40d is formed in the corner portion 40c. The edge of the rising portion 40b on the inner diameter side is V-shaped, similar to the groove 28. FIG. 14 is an exploded perspective view that illustrates the positional relationship between the two spacing members 40 and the cover members 20A and 20B on both sides.

[0033] The spacing member 40 can be made of various elastic materials that can maintain the sealing properties of the joint. Normally, as in this embodiment, cork is used, which has a heat resistance of 200°C or more. However, other materials such as paper, nonwoven fabric, and the like can also be used depending on the conditions of use of the coupling.

[0034] In the coupling structure of this invention, the cover 20 is provided with a spacing retaining portion that restricts the distance between the contact surfaces 24, 24 that contact the spacing member 40 when the cover 20 is tightened by the bolt 30 so that it does not become less than a predetermined value.

[0035] The spacing portion of the embodiment is composed of a protrusion 21 provided on one of the opposing contact surfaces 24, 24 and a recess 22 provided on the other, into which the protrusion 21 fits. As shown in Fig. 5, the protrusion 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 the opposing cover members 20A, 20B are fastened together, the spacing member 40 and the contact surfaces 24 do not come into excessive contact with each other, an appropriate pressure is maintained, and the cushioning function and sealing function of the spacing member 40 are not impaired.

[0036] In the 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 flat surfaces and are configured to be in surface contact with each other over their entire surfaces. If at least one of the top 21a of the protruding side of the convex portion 21 and the bottom 22a of the recessed portion 22 is not a flat surface, 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 abutment surface 24 and the depth L1 of the recessed portion 22 from the abutment surface 24 at the position where the top 21a of the protruding side of the convex portion 21 and the bottom 22a of the recessed portion 22 first abut when the opposing cover members 20A, 20B are brought close to each other and the convex portion 21 enters the recessed portion 22.

[0037] Here, if the thickness of the spacing member 40 before tightening (before use) is t0 and the thickness under appropriate pressure is t1, then: L2-L1=t1...(Formula 1) It is desirable to set the following. If an error α is allowed, t1+α>L2-L1>t1-α (Formula 2) Also, t0>L2-L1...(Formula 3) It is required that:

[0038] In this way, by providing a spacing retaining portion on the cover 20, excessive or insufficient tightening is eliminated, making it possible to easily manage the tightening strength of the two cover members 20A, 20B sandwiching the spacing member 40.

[0039] In the embodiment, the spacing portion is provided around the entire axis of the bolt 30. Specifically, the convex portions 21 and the concave portions 22 that constitute the spacing 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 against the spacing member 40 around the bolt 30, where excessive tightening is likely to occur. In particular, in the embodiment, the convex portions 21 and the concave portions 22 have circular cross sections, and the centers of the convex portions 21 and the concave portions 22 of the circular cross sections are located on the axis of the bolt 30 (the axis of the bolt holes 26 and 27), which further reliably ensures that an appropriate pressing force is applied around the bolt 30.

[0040] In the embodiment, the spacing portion is provided around the entire axis of the bolt 30, but the position of the 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, a configuration is also possible in which the spacing portion is provided at a position away from the bolt holes 26, 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] 15 and 16 show modified examples of the spacing retaining portion. In this modified example, the spacing retaining portion in the above embodiment is configured such that the top 21a of the convex portion 21 does not abut against the bottom 22a of the concave portion 22, but the outer surface tapered portion 21b formed on the edge of the convex portion 21 abuts against the inner surface tapered portion 22b formed on the edge of the concave portion 22. In the embodiment, the outer surface tapered portion 21b is provided around the entire periphery of the edge of the convex portion 21, and the inner surface tapered portion 22b is provided around the entire periphery of the edge of the concave portion 22, but these may also be part of the respective edges.

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

[0043] 15 and 16, when the outer surface tapered portion 21b and the inner surface tapered portion 22b come into surface contact and further tightening is no longer possible, the top 21a of the convex portion 21 does not come into contact with the bottom 22a of the concave portion 22. In this embodiment, the protruding 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] 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 21a of the convex portion 21 abuts against the bottom 22a of the concave portion 22. In this case as well, if the thickness of the spacing member 40 under the appropriate pressure is t1, allowing for an error α, t1+α>L2-L1>t1-α (Formula 2) It is required that:

[0045] In the modified example shown in FIG. 17, the configurations of the outer surface tapered portion 21b and the inner surface tapered portion 22b are the same as those in the modified examples shown in FIGS.

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

[0047] In conventional coupling structures, excessive tightening of the opposing cover members 20A, 20B can cause the spacing member 40 to shrink excessively, or conversely, insufficient tightening can prevent the original sealing function from being achieved. However, according to the present invention, a spacing retaining portion is provided 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, making it easy to control the tightening strength. In other words, it is easy to control the thickness of the spacing member (packing / gasket) 40 after tightening and the degree of adhesion.

[0048] Furthermore, with conventional coupling structures, it has been difficult to align the opposing cover members 20A, 20B when tightening them together. Conventionally, alignment was performed by feel and visual inspection, using the clearance between the outer periphery of the tightening bolt and the inner surface of the mounting hole as a guide. However, with this invention, alignment is easily achieved by fitting the convex portions 21 of the opposing cover members 20A, 20B into the concave portions 22, reducing the time and effort required for the work and improving the finish accuracy. [Explanation of symbols]

[0049] 1 Chain Coupling 2nd and 3rd axes 2a, 3a Sprocket (locking body) 4 O-ring (seal ring) 10 Chain (rotating transmission element) 20 Chain sprocket cover 20A, 20B Cover member 21 Convex part 22 recess 24 Contact surface part 30 volts 31 Cylindrical part 32 End wall 40 Spacing member

Claims

1. 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 a direction around the axis; an endless rotary power 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 power transmission body (10); a spacing member (40) that is arranged between opposing abutment 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 abutment surfaces (24, 24), a spacing retaining portion that restricts the distance between the contact surfaces (24, 24) that contact the spacing member (40) so that the distance does not become equal to or less than a predetermined value when the bolt (30) is tightened; The spacing portion is a convex portion (21) provided on one of the opposing contact surfaces (24, 24) and a concave portion (22) provided on the other of the contact surfaces (24, 24) into which the convex portion (21) fits, and the coupling structure is such that the top (21a) of the convex portion (21) abuts against the bottom (22a) of the concave portion (22).

2. 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 a direction around the axis; an endless rotary power 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 power transmission body (10); a spacing member (40) that is arranged between opposing abutment 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 abutment surfaces (24, 24), a spacing retaining portion that restricts the distance between the contact surfaces (24, 24) that contact the spacing member (40) so that the distance does not become equal to or less than a predetermined value when the bolt (30) is tightened; The spacing portion is a convex portion (21) provided on one of the opposing contact surfaces (24, 24) and a concave portion (22) provided on the other of the contact surfaces (24, 24) into which the convex portion (21) fits, and a coupling structure in which an outer tapered portion (21b) formed on the edge of the convex portion (21) abuts against an inner tapered portion (22b) formed on the edge of the concave portion (22).

3. 3. The coupling structure according to claim 1, wherein the spacing portion is provided around the entire periphery of the bolt (30).

4. 3. The coupling structure according to claim 1, wherein the spacing portion is provided between one of the bolts (30) and another of the bolts (30).

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