SHAFT COUPLING

Abstract

A slotted-type rigid coupling is manufactured so that the internal-diameter dimension of a first shaft hole of a circumferentially divided shaft-fastening part is the same as that of a shaft. The first shaft hole is widened by widening force from a pressing mechanism provided with a fastening bolt, and the shaft is inserted through the first shaft hole up to a shaft insertion hole. The widening force is ceased, the first shaft hole is narrowed by fastening force from the pressing mechanism, and the shaft is securely fastened. When the shaft is securely fastened to the shaft-fastening part by the fastening bolt, eccentricity in the shaft is prevented or minimized.

Claims

1. A shaft coupling comprising: a tubular coupling main body; a first slit that, in a position at a predetermined distance in an axial direction from one first end face of the coupling main body, divides the coupling main body over a predetermined angular range in the axial direction; a shaft-fastening part defined by a portion of the coupling main body from the first end face to the first slit; a second slit that circumferentially divides the shaft-fastening part; a fastening shaft hole that is defined by an inner peripheral surface of the shaft-fastening part and that opens in the first end face; and a pressing mechanism capable of generating widening force and fastening force to deform the shaft-fastening part in directions whereby first and second circumferential end faces of the shaft-fastening part, which oppose each other across the second slit, are caused to move away from and toward each other; wherein the fastening shaft hole has an internal-diameter dimension such that an interference fit or a transition fit can be formed with a shaft to be fastened when the shaft-fastening part is in a pre-deformed state; and the fastening shaft hole has an internal-diameter dimension such that a gap is formed with the shaft in a widened state in which the pressing mechanism exerts the widening force having a predetermined value.

2. The shaft coupling according to claim 1, wherein, when an end part on a side of the shaft-fastening part having the first circumferential end face is designated as a first circumferential end part and another end part on a side of the shaft-fastening part having the second circumferential end face is designated as a second circumferential end part, the pressing mechanism has: a bolt insertion hole formed in the first circumferential end part; a bolt screw hole formed in the second circumferential end part; and a fastening bolt which is disposed being screwed into the bolt screw hole through the bolt insertion hole and which is engaged in the first circumferential end part so as to not move toward or away from the second circumferential end part.

3. The shaft coupling according to claim 2, wherein the pressing mechanism has a bolt-engaging pin secured to the first circumferential end part; the fastening bolt has a bolt head part that is engaged with the first circumferential end part from an opposite side from the second circumferential end part; and the bolt-engaging pin is engaged with the bolt head part from the opposite side from the second circumferential end part.

4. The shaft coupling according to claim 1, wherein the coupling main body has an adjacent tubular part adjacent to the shaft-fastening part, the adjacent tubular part having a shaft insertion hole coaxially joined to the fastening shaft hole; and the shaft insertion hole is a hole into which a tip portion of the shaft inserted in the fastening shaft hole is inserted, the shaft insertion hole having an internal-diameter dimension larger than the outside-diameter dimension of the shaft.

5. The shaft coupling according to claim 4, wherein, when an end part on a side of the shaft-fastening part having the first circumferential end face is designated as a first circumferential end part and another end part on a side of the shaft-fastening part having the second circumferential end face is designated as a second circumferential end part, the pressing mechanism has: a bolt insertion hole formed in the first circumferential end part; a bolt screw hole formed in the second circumferential end part; a fastening bolt disposed being screwed into the bolt screw hole through the bolt insertion hole; and a bolt-engaging pin secured to the first circumferential end part, wherein the fastening bolt has a bolt head part that is engaged with the first circumferential end part from an opposite side from the second circumferential end part; and the bolt-engaging pin is engaged with the bolt head part from the opposite side from the second circumferential end part, and wherein, in the pre-deformed state, the fastening bolt is in a first position in which it is screwed into the bolt screw hole by a predetermined amount; in the widened state, the fastening bolt is in a second position in which it is pulled out from the bolt screw hole than the first position; and in a fastening state in which the fastening force having a predetermined value is applied to the shaft fastening part, the fastening bolt is in a third position in which it is screwed further into the bolt screw hole than the first position.

6. The shaft coupling according to claim 1, wherein the coupling main body has an adjacent tubular part adjacent to the shaft-fastening part, the adjacent tubular part having a shaft insertion hole coaxially joined to the fastening shaft hole; the shaft insertion hole has an internal-diameter dimension larger than the outside-diameter dimension of a shaft to be fastened; the coupling main body has a shaft-linking tubular part having a predetermined length along the axial direction from a second end face on an opposite side from the first end face; and a second shaft hole that opens in the second end face is defined by a circular inner peripheral surface of the shaft-linking tubular part.

7. The shaft coupling according to claim 6, wherein, when an end part on a side of the shaft-fastening part having the first circumferential end face is designated as a first circumferential end part and another end part on a side of the shaft-fastening part having the second circumferential end face is designated as a second circumferential end part, the pressing mechanism has: a bolt insertion hole formed in the first circumferential end part; a bolt screw hole formed in the second circumferential end part; a fastening bolt disposed being screwed into the bolt screw hole through the bolt insertion hole; and a bolt-engaging pin secured to the first circumferential end part, wherein the fastening bolt has a bolt head part that is engaged with the first circumferential end part from an opposite side from the second circumferential end part; and the bolt-engaging pin is engaged with the bolt head part from the opposite side from the second circumferential end part, and wherein, in the pre-deformed state, the fastening bolt is in a first position in which it is screwed into the bolt screw hole by a predetermined amount; in the widened state, the fastening bolt is in a second position in which it is pulled out from the bolt screw hole than the first position; and in a fastening state in which the fastening force having a predetermined value is applied to the shaft fastening part, the fastening bolt is in a third position in which it is screwed further into the bolt screw hole than the first position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1 is a perspective view showing a state in which two shafts are linked to a rigid-type shaft coupling to which the present invention is applied;

[0037] FIG. 2 is a perspective view showing the shaft coupling of FIG. 1 in a state of being sectioned through a plane including the axis line of the shaft coupling;

[0038] FIG. 3 is an enlarged partial cross-sectional view showing the inner peripheral surface of a hole in the shaft coupling of FIG. 2; and

[0039] FIGS. 4(a) and 4(b) include a partial perspective view showing a pressing mechanism of a shaft-fastening part of the shaft coupling of FIG. 1, and a transverse cross-sectional view showing the shaft-fastening part thereof.

MODE FOR CARRYING OUT THE INVENTION

[0040] An embodiment of a shaft coupling to which the present invention is applied is described below with reference to the drawings.

[0041] FIG. 1 is a perspective view showing a rigid-type shaft coupling (referred to below as a rigid coupling) to which the present invention is applied, FIG. 2 is a perspective view of the shaft coupling sectioned through a plane including the axis line of the shaft coupling, and FIG. 3 is an enlarged partial cross-sectional view showing the inner peripheral surface of a hole in the rigid coupling.

[0042] To give a description with reference to these drawings, the rigid coupling 1 has a cylindrical coupling main body 2 and a pressing mechanism 4 provided with a fastening bolt 3. One shaft 6 to be linked is inserted into a first shaft hole 5 (fastening shaft hole) that opens in an end face 2a of the coupling main body 2 on one side along the direction of an axis line 1a, and the shaft 6 is securely fastened in a coaxial state to the coupling main body 2 by the fastening bolt 3. Another shaft 8 to be linked is, for example, press-fitted and secured in a coaxial state in a second shaft hole 7 opened in the other end face 2b of the coupling body 2 on the other side along the direction of the axis line 1a. This forms a state in which both shafts 6, 8 are coaxially linked via the rigid coupling 1.

[0043] In the coupling main body 2, a large-diameter cylindrical part 11, a cylindrical part 12 smaller in diameter thereto, and a cylindrical part 13 even smaller in diameter thereto are coaxially formed from the one end face 2a toward the other end face 2b. In the large-diameter cylindrical part 11, a first slit 14 that has constant width and that extends in a circumferential direction over an angular range of about 180 degrees is formed in a position at a predetermined distance from the one end face 2a along the direction of the axis line 1a. The portion of the cylindrical part 11 where the first slit 14 is formed is divided along the direction of the axis line 1a by the first slit 14.

[0044] Also formed in the cylindrical part 11 is a second slit 15 that has constant width and that extends from the end face 2a in the direction of the axis line 1a. The second slit 15 leads into the first slit 14 and extends to a position past the first slit 14. A portion in the cylindrical part 11 from the end face 2a to the first slit 14 is circumferentially divided by the second slit 15. The portion where the second slit 15 is formed functions as a shaft-fastening part 16 for securely fastening the shaft 6 with the use of the fastening bolt 3.

[0045] The first shaft hole 5 that opens in the end face 2a of the coupling main body 2 is a hole portion defined by a circular inner peripheral surface 16a of the shaft-fastening part 16 in the cylindrical part 11, as shown in FIGS. 2 and 3. An adjacent cylindrical portion 17 is formed adjacent to the shaft-fastening part 16 in the cylindrical part 11, and a circular shaft insertion hole 18 is formed up to a position partway along the cylindrical part 12. The shaft insertion hole 18 leads coaxially into the first shaft hole 5. The one shaft 6 to be linked is inserted through the first shaft hole 5 from the side having the end face 2a, up to a position partway along the shaft insertion hole 18.

[0046] Conversely, the second shaft hole 7 that opens in the other end face 2b is a circular shaft hole smaller in diameter than the first shaft hole 5, and the second shaft hole 7 extends up to a position in the cylindrical part 13 partway along the direction of the axis line 1a. The second shaft hole 7 and the shaft insertion hole 18 are formed coaxially and are joined to each other via a circular communication hole 19 that is smaller in diameter than both the other holes.

[0047] In this embodiment, the first shaft hole 5 into which the shaft 6 is inserted is manufactured so that the internal-diameter dimension d(5) of the first shaft hole 5 is the same dimension as the outside-diameter dimension d(6) of the shaft 6, as shown in FIG. 3. In other words, the first shaft hole 5 is machined so that the fit tolerance thereof relative to the shaft 6 is a transition fit. Conversely, the internal-diameter dimension d(18) of the shaft insertion hole 18 is set to a size such that a gap will assuredly be formed between the shaft insertion hole 18 and the shaft 6. In other words, the shaft insertion hole 18 is machined so that the fit tolerance of the shaft insertion hole relative to the shaft 6 is plus. Therefore, an arcuate step-difference face 20 is created between the circular inner peripheral surface 16a of the shaft-fastening part 16 and a circular inner peripheral surface 18a (continuous with the circular inner peripheral surface 16a) of the shaft insertion hole 18.

[0048] Next, FIG. 4(a) is a partial perspective view showing the pressing mechanism 4 of the shaft-fastening part 16 of the rigid coupling 1, and FIG. 4(b) is a transverse cross-sectional view of the same.

[0049] The pressing mechanism 4 deforms the shaft-fastening part 16, which is circumferentially divided by the second slit 15, in a widening direction and a narrowing direction. The shaft-fastening part 16 is divided by the second slit 15, and a first circumferential end face 21a and a second circumferential end face 22a oppose each other across the second slit 15. The pressing mechanism 4, with the use of the hexagonal holed fastening bolt 3, is capable of deforming the shaft-fastening part 16 in directions in which the first and second circumferential end faces 21a, 22a draw apart and draw closer together.

[0050] Designating the end part on the side of the shaft-fastening part 16 that has the first circumferential end face 21a as a first circumferential end part 21 and the end part on the side that has the second circumferential end face 22a as a second circumferential end part 22, the pressing mechanism 4 is provided with a bolt insertion hole 23 formed in the first circumferential end part 21 and a bolt screw hole 24 formed in the second circumferential end part 22. A recess 25 exposed in the outer peripheral surface is formed in the first circumferential end part 21, and the bolt insertion hole 23 is opened in an end face 25a of the recess 25. The bolt insertion hole 23 and the bolt screw hole 24 are formed coaxial to a direction orthogonal to the second slit 15 (a direction orthogonal to the radial direction of the shaft-fastening part 16). The fastening bolt 3 is disposed in a state of having been screwed into the bolt screw hole 24 through the bolt insertion hole 23.

[0051] In this embodiment, the fastening bolt 3 is engaged with the first circumferential end part 21 so as to not move in the direction of drawing nearer to or the direction of drawing away from the second circumferential end part 22. Specifically, a bolt head part 3a of the fastening bolt 3 is in contact with the end face 25a of the recess 25 in which the bolt insertion hole 23 opens. Additionally, the pressing mechanism 4 is provided with a bolt-engaging pin 26 secured to the first circumferential end part 21. The bolt-engaging pin 26 is pushed in from the end face 2a of the coupling body 2 in a direction along the axis line 1a, and a pin leg part 26a of the bolt-engaging pin 26 protrudes into the recess 25. The pin leg part 26a is engaged with the bolt head part 3a from the opposite side from the second circumferential end part 22. Specifically, the pin leg part 26a is engaged with the bolt head part 3a at a position offset from the center of the bolt head part 3a, so as to not interfere with a bolt-fastening tool inserted into the hexagonal hole for the bolt head part 3a.

[0052] The procedure of coaxially linking the shaft 6 in the first shaft hole 5 for fastening of the rigid coupling 1 shall now be described. In the initial state, the fastening bolt 3 is in a first position of being screwed a predetermined amount into the bolt screw hole 24. In this state, the shaft-fastening part 16 has its original shape, and the internal-diameter dimension d(5) of the first shaft hole 5 is a dimension that allows a transition fit with the outside-diameter dimension d(6) of the shaft 6.

[0053] In this state (the pre-deformed state), the fastening bolt 3 is turned by a predetermined amount in the direction in which the fastening bolt 3 is pulled out of the bolt screw hole 24. The bolt head part 3a of the fastening bolt 3 is held in the direction of a bolt axis line 3b between the end face 25a of the recess 25 of the first circumferential end part 21 and the bolt-engaging pin 26 secured to the first circumferential end part 21. The fastening bolt 3 is turned by a predetermined amount in the pulling out direction and moved to a second position. The first circumferential end part 21 is thereby pushed in a direction away from the second circumferential end part 22 by the fastening bolt 3, which has been moved in a direction of being pulled out from the side having the second circumferential end part 22. As a result, the slit width of the second slit 15 widens and the first shaft hole 5 is widened to become larger than the shaft 6 (a widened state). The shaft 6 can thereby be inserted into the first shaft hole 5. The shaft 6 is inserted from the first shaft hole 5 up to a position partway through the shaft insertion hole 18.

[0054] Thereafter, the fastening bolt 3 is turned in a direction of being screwed into the bolt screw hole 24 and moved to a third position toward the second circumferential end part 22 from the initial first position. The first circumferential end part 21 is pushed in a direction of drawing close to the second circumferential end part 22 in the amount by which the fastening bolt 3 is screwed into the second circumferential end part 22. Consequently, the second slit 15 is enclosed, the first shaft hole 5 is narrowed, and a securely fastened state is formed in which the shaft 6 inserted into the first shaft hole 5 is securely fastened.

[0055] Thus, the first shaft hole 5 is set so that the fit tolerance with the shaft 6 is a transition fit, the first shaft hole 5 is forcefully widened, the shaft 6 is inserted, and the first shaft hole 5 is thereafter narrowed further to its original state. Consequently, unlike a case in which a shaft is inserted into a shaft hole so as to have a clearance fit and the shaft hole is constricted, a gap is not formed between the shaft hole and the shaft during fastening, and the shaft can therefore be securely fastened without misalignment.

[0056] The internal-diameter dimension d(18) of the shaft insertion hole 18 on the side further within than the first shaft hole 5 is slightly larger than the shaft 6. Therefore, when the shaft-fastening part 16 is fastened, the shaft 6 is not pressed in the radial direction by the inner peripheral surface portion of the shaft insertion hole 18 joining to the shaft-fastening part 16, and no tilt is caused. Consequently, the shaft can be securely fastened without being tilted.

Other Embodiments

[0057] The above embodiment is a case in which the present invention is applied to a rigid coupling. The present invention can be similarly applied to a flexible-type shaft coupling as well. For example, the present invention can be applied to the shaft coupling illustrated in FIGS. 8 and 9 of Patent Document 2 (JP-A 2008-241029), and to the shaft coupling illustrated in FIG. 3 of Patent Document 3 (JP-A 2001-295851).

[0058] For example, such a shaft coupling is provided with a slotted tubular first linking member having a shaft hole in which one shaft to be linked is securely fastened, a slotted second linking member having a shaft hole in which another shaft to be linked is securely fastened, and an elastic body or a third metal body that coaxially links and integrates the first and second linking members. The elastic body is a molded article formed from, e.g., hydrogenated nitrile rubber vulcanized with peroxide, hydrogenated nitrile rubber vulcanized with sulfide, butyl rubber, nitrile rubber, propylene rubber, fluororubber, etc., and the first and second linking members are integrated through the elastic member by, e.g., insert molding. The third metal body is machined using, e.g.: A2017, A7075, or another form of aluminum; SUS303, SUS304, or another form of stainless steel; S45C or another form of iron; etc., and the first and second linking members are integrated via the third metal body by, e.g., fastening with screws.

[0059] In this case, for example, a tubular coupling main body in the previously described embodiment is configured from a first linking member to which one shaft is securely fastened, a second linking member to which another shaft is securely fastened, and an elastic member or third metal body that links the first and second linking members. For example, the first linking member preferably has the following configuration.

[0060] Specifically, the first linking member has, in positions at predetermined distances along an axial direction from one first end face of the first linking member: a first slit that divides the first linking member over a predetermined angular range along the axial direction; a shaft-fastening part defined by the portion of the first linking member from the first end face to the first slit; a second slit that circumferentially divides the shaft-fastening part; a fastening shaft hole that is defined by the inner peripheral surface of the shaft-fastening part and that opens in the first end face; and a pressing mechanism capable of generating widening force and fastening force that deforms the shaft-fastening part in directions whereby first and second circumferential end faces of the shaft-fastening part, which oppose each other across the second slit, are caused to draw away from and toward each other. With the shaft-fastening part in a pre-deformed state, the fastening shaft hole has an internal-diameter dimension such that an interference fit or a transition fit can be formed with the shaft to be fastened, and in a widened state in which the pressing mechanism exerts a predetermined widening force, the fastening shaft hole has an internal-diameter dimension such that a gap is formed with the shaft.