JP2000055070A - Coupling device for rotating equipment - Google Patents

Abstract

An object of the present invention is to provide a highly durable rotating device coupling device that can more effectively prevent the occurrence of wear and the like by changing the shape of components of the coupling device. . SOLUTION: In a clearance between an outer peripheral surface of a pump shaft 1 and an inner peripheral surface of a pump shaft insertion hole 2, a clearance C1 at a position corresponding to each key 4, 5 protruding position of the coupling 8 is made larger than clearances at other positions. Form small. For example, the pump shaft insertion hole 2 is formed in a substantially circular shape, and portions of the inner peripheral surface of the insertion hole 2 corresponding to the protruding positions of the keys 4, 5 are formed on a flat surface 2A parallel to the pins 9, 10. , After securing the required amount of coupling play (clearance C) in the pin axis direction,
The clearance C1 between the outer peripheral surface of the pump shaft 1 and the inner peripheral surface of the pump shaft insertion hole 2 at a position corresponding to the five protruding positions is made small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coupling device for rotating equipment such as a fuel pump for an internal combustion engine.
The present invention relates to a technology for improving the durability.

[0002]

2. Description of the Related Art Conventionally, a fuel pump of an internal combustion engine as a rotating device is driven in synchronization with rotation of a crankshaft of an engine as a rotating shaft on a driving source side. For this reason, the fuel pump is driven by linking a sprocket, a pulley, and the like attached to the drive shaft thereof with a sprocket, a pulley, and the like attached to the crankshaft by a chain, a belt, and the like.

Alternatively, similarly to a distributor, a fuel pump may be driven in synchronization with the rotation of a camshaft provided so as to rotate synchronously with a crankshaft. In general, it is directly bonded to
0410). As a structure for directly coupling the fuel pump to the camshaft, the drive shaft (pump shaft) end of the fuel pump is connected to the camshaft end via a coupling device.

FIGS. 8 and 9 show a coupling structure using this coupling device. The coupling device includes a coupling 8 connected to one end of the pump shaft 1. FIG.
A connecting portion for connecting the coupling 8 is provided at an end of the camshaft 11. Here, the coupling 8 has keys 4 and 5 projecting from two opposing positions on the outer peripheral surface of the substantially cylindrical main body 3 in which the circular pump shaft insertion hole 2 is formed in a direction perpendicular to the axis. Key 4,
Pin holes 6 and 7 are formed at two positions orthogonal to and opposite to the extending direction of pin 5.

On the other hand, a single pin is fixedly penetrated to one end of the pump shaft 1 and the outer peripheral surface of the end is opposed to two pins.
The position is at the end of the single pin in a direction perpendicular to the axis
Pin ends 9 and 10 are projected. A concave portion 12 is formed on the end face of the end of the camshaft 11, and key grooves 13 and 14 are formed at two opposing positions on the end wall.

Then, with the cam shaft 11 end inserted into the pump shaft insertion hole 2 of the coupling 8, the pin ends 9, 10 are inserted into the pin holes 6, 7, and the cam shaft 11 is inserted into the cam shaft 11. The coupling 8 is mounted, and the keys 4 and 5 of the coupling 8 are inserted into the key grooves 13 and 14 at the end of the camshaft 11 to engage with each other.
The end of the camshaft 11 and the end of the pump shaft 1 are connected.

[0007]

However, in such a conventional coupling device, the pump shaft insertion hole 2 of the coupling 8 has a perfect circular shape.
The following problems arise because the keys 4 and 5 have a uniform rectangular cross-sectional shape such as a square from the base to the tip of the coupling body 3.

That is, in such a coupling device, it is necessary to provide an amount of coupling play in order to allow the movement of the cam shaft 11 at the end and the pump shaft 1 at the connection thereof. For example, the required amount of coupling play in the axial direction of the pin is determined by measuring the inner peripheral surface of the pump shaft insertion hole 2 (inner diameter D1) at the pin ends 9, 10 and the pin holes 6, 7 and the pump shaft 1 (outer diameter D2). It is set by providing a predetermined clearance (= D1-D2) between the outer peripheral surface.

When the pump shaft insertion hole 2 has a perfect circular shape as in the prior art, as a result of securing the clearance in the pin axis direction, the entire inner peripheral surface of the pump shaft insertion hole 2 and the entire outer peripheral surface of the pump shaft 1 are formed. During this time, this clearance will be formed. As shown in FIG. 9, the clearance is formed as a whole, and there is a large clearance between the inner peripheral surface of the pump shaft insertion hole 2 and the outer peripheral surface of the pump shaft 1 at positions corresponding to the positions of the keys 4 and 5. The coupling 8 is tilted (tilt θ1)
When assembled to the camshaft 11, this inclination θ
1 is large, so that one key 4 and the keyway 13
The contact area (engagement area) B between the other key 5 and the key groove 14 is smaller than the contact area (engagement area) A with the key.

The contact area (engagement area) B becomes smaller and the contact surface pressure becomes higher as the inclination θ of the coupling becomes larger. There is a possibility that the wear of the 14 portion may be accelerated or the durability of the portion may be reduced due to stress concentration. In particular, in the case of a high-pressure fuel pump, it is necessary to take a relatively large amount of coupling play in the pin axial direction, so that the above-mentioned problem occurs more remarkably.

Conventionally, as shown in FIG. 10, the keys 4 and 5 have a rectangular cross section such as a quadrangle.
Further, since the clearance is provided between the side surfaces of the keys 4 and 5 and the inner surfaces of the key grooves 13 and 14, the following problem occurs. That is, the rear side surface 4B (only one key 4 is shown) of the keys 4 and 5 in the camshaft rotation direction is the camshaft 11
As shown in FIG. 10, the keys 4 and 5 hit the tip edges of the key grooves 13 and 14 (line contact), and the key of the cam shaft 11 is rotated. Stress concentrates on the grooves 13 and 14.

Furthermore, in the conventional coupling device, the weakest part, that is, the weak part is the keyway 13,
For example, in the case of a high-pressure fuel pump, fragments may fall off due to breakage of the fragile portion at the time of baking. In view of the above-mentioned conventional problems, the present invention provides a highly durable rotating device coupling device that can more effectively prevent the occurrence of wear and the like by changing the shape of the components of the coupling device. The purpose is to provide.

[0013]

According to a first aspect of the present invention, there is provided a coupling device for connecting a drive shaft end of a rotary device to a drive shaft end of a drive source. A key protrudes from two opposing positions on the outer peripheral surface of the cylindrical coupling body having the insertion hole formed therein in a direction perpendicular to the axis, and the key extends perpendicularly to the direction in which the key extends on the wall of the coupling body. A coupling having pin holes penetratingly formed at two positions facing each other is provided, while two opposite positions on the outer peripheral surface of the drive shaft end of the rotating device are projected in the direction perpendicular to the axis and inserted into the pin holes. A pin is attached, and a concave portion is formed on the end surface of the end of the rotary shaft on the drive source side,
A coupling device having a configuration in which key grooves into which the keys are inserted and meshed are formed at two opposing positions of an end wall around the concave portion, respectively. The clearance at the position corresponding to each key protruding position of the coupling among the clearances between the inner peripheral surfaces of the insertion holes is formed to be smaller than the clearances at other positions.

According to a second aspect of the present invention, the drive shaft insertion hole of the rotating device of the coupling is formed in a substantially circular shape.
A portion corresponding to each key protruding position on the inner peripheral surface of the insertion hole is formed in a flat surface. The invention according to claim 3 is that the drive shaft insertion hole of the rotating device of the coupling is formed in a substantially rectangular shape, and two long sides of the insertion hole are set on the side corresponding to each key protruding position of the coupling. The two short sides are on the side corresponding to each pin projecting position of the drive shaft of the rotating device.

According to a fourth aspect of the present invention, there is provided a coupling device for connecting an end of a drive shaft of a rotary device to an end of a rotary shaft on a drive source side, wherein the drive shaft has an insertion hole formed therein. A key is projected from two opposing positions on the outer peripheral surface of the coupling main body in a direction perpendicular to the axis, and pin holes penetrate at two opposing positions orthogonal to the direction in which the key extends on the wall of the coupling main body. A driving unit that includes a coupling formed at two opposite positions on an outer peripheral surface of a drive shaft end of the rotating device, the pin being inserted in the pin hole and protruding in a direction perpendicular to the axis; A concave portion is formed on the end surface of the end portion of the rotating shaft on the side, and key grooves into which the keys are inserted and meshed are formed at two opposing positions of the end wall around the concave portion. The coupling device according to claim 1, wherein Characterized in that a weak portion on the side of the rear surface of the rotational shaft direction of rotation of the drive source side of the keyway inner surface opposed to the side surface of the base end portion of each key of the grayed.

The invention according to claim 5 is characterized in that the fragile portion is formed by providing a groove on the rear surface in the direction of rotation of the rotary shaft on the drive source side. In the invention according to claim 6, the weak portion has a thickness from a central axis of a base end portion of each key of the coupling to a rear surface in a rotation axis rotation direction on the drive source side, to an opposite surface. It is characterized by being formed by making it smaller than the wall thickness of the.

According to a seventh aspect of the present invention, the key is located at a position closer to the distal end than the fragile portion on both sides opposite to the inner surfaces on both sides of the key groove at the base end of each key of the coupling. The present invention is characterized in that each of the projecting stoppers is provided, and the length between the front end surfaces of both stoppers is formed larger than the inner width of the key groove.

An invention according to claim 8 is a coupling device for connecting an end of a drive shaft of a rotary device to an end of a rotary shaft on a drive source side, wherein the drive shaft has an insertion hole formed therein. A key is projected from two opposing positions on the outer peripheral surface of the coupling main body in a direction perpendicular to the axis, and pin holes penetrate at two opposing positions orthogonal to the direction in which the key extends on the wall of the coupling main body. A driving unit that includes a coupling formed at two opposite positions on an outer peripheral surface of a drive shaft end of the rotating device, the pin being inserted in the pin hole and protruding in a direction perpendicular to the axis; A concave portion is formed on the end surface of the end portion of the rotating shaft on the side, and key grooves into which the keys are inserted and meshed are formed at two opposing positions of the end wall around the concave portion. In the coupling device of the above, The rear side of the drive shaft in the direction of rotation of the drive source side, which is the side facing the key groove inner surface, is formed into a tapered surface such that the key thickness decreases from the base end to the tip end. Features.

According to a ninth aspect of the present invention, in the invention according to the eighth aspect, instead of the tapered surface of the side face facing the inner surface of each key groove of each key of the coupling, the rotation axis rotation of each key on the drive source side is provided. A tapered surface is formed on the key groove inner surface facing the rear side surface of the key so that the key groove inner width increases from the portion corresponding to the base end of each key to the portion corresponding to the tip end. It is characterized by.

The operation of the present invention will be described. In the invention according to claim 1, the following operation is achieved by forming a small clearance between the outer peripheral surface of the drive shaft and the inner peripheral surface of the drive shaft insertion hole at a position corresponding to each key projecting position of the coupling. That is, when the coupling is assembled to the rotation shaft on the drive source side in an inclined state, the inclination can be reduced, whereby the contact area (engagement area) between one key and the key groove is reduced. The contact area (engagement area) between the key and the key groove can be prevented from being significantly reduced.

Accordingly, the contact surface pressure can be reduced, and the stress can be prevented from being concentrated on the key groove portion of the rotary shaft on the drive source side. In this case, in the invention according to claim 2,
The invention according to claim 3, wherein the rotary device drive shaft insertion hole of the coupling is formed in a substantially circular shape, and a portion of the inner peripheral surface of the insertion hole corresponding to each key protruding position is formed in a flat surface. Is to form a drive shaft insertion hole of a coupling in a substantially rectangular shape and set two long sides of the insertion hole to a side corresponding to each key protruding position of the coupling.
By setting the two short sides to the side corresponding to each pin projecting position of the rotating device drive shaft, the outer peripheral surface of the rotating device drive shaft and the inner surface of the drive shaft insertion hole at the position corresponding to each key projecting position of the coupling are set. It is easy to set a small clearance.

In the invention according to claim 4, a weak portion is provided on a rear surface in a direction of rotation of a drive source side on a rotation side of a surface of the coupling which is opposed to an inner surface of a key groove at a base end of each key. As a result, when an excessive input is applied to the coupling device at the time of burning of the rotating device or the like, the key is broken at the fragile portion. That is, this serves as a torque limit effect, and wear of the keyway, coupling, and pin of the rotary shaft on the drive source side is prevented.

In this case, in the invention according to claim 5,
The fragile portion can be easily provided by, for example, a simple cutting process or the like by providing a groove on the rear surface of the drive source side in the rotation axis rotation direction. Alternatively, in the invention according to claim 6, the weak portion has an opposite thickness from the central axis of the base end of each key of the coupling to the rear surface in the rotation axis rotation direction on the drive source side. The fragile portion can be easily provided by making the thickness smaller than the thickness up to the above, that is, by setting the thickness of the key in advance.

In the invention according to claim 7, the provision of the stopper on the key prevents the broken piece from falling off. In the invention according to claim 8 and the invention according to claim 9, when the rotation shaft of the drive source rotates, the side surface of the key receives the load from the rotation shaft of the drive source side. Since the state of contact with the key side surface is surface contact, it is possible to avoid concentration of stress on the key groove portion of the rotary shaft on the drive source side.

[0025]

According to the first aspect of the invention, when the coupling is mounted on the rotary shaft on the drive source side in an inclined state, the contact surface pressure between the key and the key groove can be reduced, and the drive source can be reduced. The stress can be prevented from being concentrated on the key groove portion of the rotating shaft on the side, and the durability of the device can be improved.

According to the second and third aspects of the present invention, the clearance between the outer peripheral surface of the rotating device drive shaft and the inner peripheral surface of the drive shaft insertion hole at the position corresponding to each key protruding position of the coupling is set. It can be easily set smaller. According to the invention according to claim 4, when an excessive input is applied to the coupling device at the time of burning of the rotating device or the like,
By the torque limit action, the wear of the keyway, the coupling, and the pin of the rotary shaft on the drive source side can be prevented, and the durability of the device can be improved.

According to the fifth and sixth aspects of the invention, the fragile portion can be easily provided. According to the invention according to claim 7, the provision of the stopper on the key can prevent the broken piece from falling off. According to the inventions according to the eighth and ninth aspects, it is possible to prevent stress from being concentrated on the key groove portion of the rotary shaft on the drive source side, and to improve the durability of the apparatus.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the attached drawings. 1 and 2 are a front view and a side view showing a first embodiment of a fuel pump as a coupling device for a rotating device according to the present invention. In these figures, keys 4 and 5 are projected from two opposing positions on the outer peripheral surface of a cylindrical coupling body 3 in which an insertion hole 2 of a pump shaft 1 is formed. Couplings 8 having pin holes 6 and 7 formed therethrough are provided at two positions on the wall of the ring main body 3 and opposed to each other at right angles to the direction in which the keys 4 and 5 extend.

Pin ends 9 and 10 inserted into the pin holes 6 and 7 protrude in a direction perpendicular to the axis at two opposing positions on the outer peripheral surface of the end of the pump shaft 1. Further, a concave portion 12 is formed on an end surface of the camshaft 11 serving as a rotation shaft on the drive source side, and the keys 4 and 5 are provided at two opposing positions on an end wall around the concave portion 12. Key grooves 13 and 14 to be inserted and engaged are formed respectively.

The configuration of such a coupling device is the same as the conventional one, and the difference from the conventional one lies in the following configuration. That is, in the present invention, of the clearance between the outer peripheral surface of the pump shaft 1 and the inner peripheral surface of the pump shaft insertion hole 2, the clearance C1 at a position corresponding to each key 4, 5 projecting position of the coupling 8 is changed to another position. It is formed to be smaller than the clearance.

In the first embodiment, the pump shaft insertion hole 2 is formed in a substantially circular shape, and portions of the inner peripheral surface of the insertion hole 2 corresponding to the protruding positions of the keys 4 and 5 are pin end portions 9 and 9.
The pump shaft is formed on a flat surface 2A parallel to 10 to secure the required amount of coupling play (clearance C) in the pin axial direction, and then the pump shaft at a position corresponding to each key 4, 5 projecting position of the coupling 8. The clearance C1 between the outer peripheral surface 1 and the inner peripheral surface of the pump shaft insertion hole 2 is formed small.

Here, the distance L1 between the flat surfaces 2A is set as follows. That is, when the inner diameter of the pump shaft insertion hole 2 is D1 and the outer diameter of the pump shaft 1 is D2, L1 is set so as to satisfy D2 <(L1 + pin backlash B) <D1, and a value as close as possible to D2 is set. It is preferable that the clearance C1 be as small as possible.

The above-mentioned pin play B is determined by the pin end 9,
10 is a clearance between the outer peripheral surface and the inner peripheral surfaces of the pin holes 6 and 7. In addition, the required coupling play amount C in the pin axis direction is
Is C = (D1-D2) / 2. As described above, the outer peripheral surface of the pump shaft 1 and the pump shaft insertion hole 2 at positions corresponding to the protruding positions of the keys 4 and 5 of the coupling 8 are described.
By forming the clearance C1 between the inner peripheral surfaces small, the following operation is achieved.

That is, when the coupling 8 is assembled to the camshaft 11 in a tilted state, the tilt can be reduced, so that the contact area between one key 4 (5) and the key groove 13 (14) is reduced. The contact area (engagement area) between the other key 5 (4) and the key groove 14 (13) can be prevented from being significantly reduced with respect to (engagement area).

Accordingly, the contact surface pressure can be reduced, and the concentration of stress on the key grooves 13 and 14 of the camshaft 11 can be avoided. Next, a second embodiment will be described with reference to FIG. In this embodiment, the pump shaft insertion hole 2 of the coupling 8 is formed in a substantially rectangular shape, and the two long sides 2B (length L2: D of FIG.
1) on the side corresponding to the protruding position of each key 4, 5 of the coupling 8 and the two short sides 2C (length L3) on the side corresponding to the protruding position of each pin 4, 5 of the pump shaft 1. I made it.

In this way, after securing the required amount of coupling play C in the pin axial direction, the outer peripheral surface of the pump shaft 1 and the pump shaft insertion hole 2 at positions corresponding to the protruding positions of the respective keys 4 and 5 of the coupling 8. The clearance C1 between the inner peripheral surfaces is formed small. In this embodiment, the same operation and effect as those of the first embodiment can be obtained.

Next, a third embodiment and a fourth embodiment will be described with reference to FIGS. 4 and 5, respectively. In these embodiments, the fragile portion is provided on the rear surface of the coupling 8 in the camshaft rotation direction on the surface facing the inner surfaces of the key grooves 13 and 14 at the base ends of the keys 4 and 5. Keyway 13, 1 at the base end of each key 4, 5 of coupling 8
A stopper 1 projecting laterally from the keys 4 and 5 on both sides opposite to the inner surface on both sides of the key 4 at a position on the distal end side from the fragile portion.
5 and 16 are provided, respectively, and the length (L4) between the front end surfaces of both stoppers 15 and 16 is formed larger than the inner width (L5) of the key grooves 13 and 14 (L4> L5).

In this case, in the third embodiment shown in FIG. 4, the fragile portion is provided by providing a narrow groove 17 on the rear surface in the camshaft rotation direction. In addition, FIG.
In the embodiment, the thickness of the weak portion (L6) from the central axis of the base end of each key 4, 5 of the coupling 8 to the rear surface in the rotation direction of the camshaft is set to the opposite surface. It is provided by forming (L6 <L7) smaller than the thickness (L7) (the small thickness portion 18).

According to this embodiment, when an excessive input is applied to the coupling device at the time of burning of the fuel pump or the like, the keys 4 and 5 are broken at the fragile portions, and this serves as a torque limiting function. , The camshaft 11, the coupling 8, the pin ends 9, 10 and the like are prevented from being worn. In this case, the provision of the stoppers 15, 16 on the keys 4, 5 prevents the broken pieces from falling off.

The thickness L8 of the key in the narrow groove 17 forming portion and the small thickness portion may be set as follows. Strength limit thickness <L8 <L9 (L9: thickness of keys 4 and 5) Next, a fifth embodiment will be described with reference to FIG. In this embodiment, each key 4, 5 of the coupling 8 is
(Only 4 is shown, the same applies hereinafter).
Only the rear side in the camshaft rotation direction of the side facing the inner surface is formed such that the thickness of the keys 4 and 5 decreases from the base end to the tip. It is formed on a tapered surface 4A (only the key 4 side is shown).

In this case, the tapered surface 4A is
14 is formed to have an angle of θ with the inner surface. According to such an embodiment, the sides of the keys 4 and 5 are
During rotation of the camshaft 11, the surface receiving the load from the camshaft 11 is brought into contact. However, since the contact state between the inner surfaces of the keyways 13 and 14 and the side surfaces of the keys 4 and 5 is in surface contact, the keyways 13 and 14 Concentration of stress on the part can be avoided.

As shown in FIG. 7, the key grooves 1 facing the rear side surfaces of the keys 4 and 5 in the camshaft rotation direction.
The key grooves 1 are formed on the inner surfaces of the keys 3 and 14 from the portion corresponding to the base end of each of the keys 4 and 5 to the portion corresponding to the front end.
The same effect can be obtained by forming the tapered surface 13A such that the inner widths of the third and the fourth are large (sixth embodiment).

Incidentally, the constructions (1) to (1) of each embodiment shown below.
(3) may be implemented in combination as follows. (1), (2) (1), (3) (2), (3) (1), (2), (3) (1) Between the outer peripheral surface of the pump shaft 1 and the inner peripheral surface of the pump shaft insertion hole 2 (2) The base end of each key 4, 5 of the coupling 8 in which the clearance C1 at the position corresponding to the projecting position of each key 4, 5 of the coupling 8 is smaller than the clearance at the other position. A weak portion is provided on the rear surface in the camshaft rotation direction of the surfaces facing the inner surfaces of the key grooves 13 and 14 of the portion, and the key grooves 13 and 14 at the base ends of the keys 4 and 5 of the coupling 8 are provided. Stoppers 15, 16 protruding to the sides of the keys 4, 5 on both sides opposite to the inner surfaces on both sides of the key 14, at positions more distal than the fragile portion.
Are provided, and the length (L
4) is formed larger than the inner width (L5) of the key grooves 13 and 14 (L4> L5). (3) The side of the key of the coupling facing the inner surface of each key groove has a key base end. From the point corresponding to the base end of each key, to the point corresponding to the tip end, from the point corresponding to the base end of each key to the point corresponding to the point formed on the tapered surface so that the key thickness becomes smaller toward the tip end. Forming a tapered surface so that the inner width of the key groove becomes large. In the above embodiment, the coupling device of the fuel pump has been described. However, the present invention can be applied to the coupling device of other rotating devices. The same operation and effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view showing a first embodiment of a fuel pump as a coupling device for a rotating device according to the present invention.

FIG. 2 is a side view showing only the coupling.

FIG. 3 is a side view showing only the coupling according to the second embodiment;

FIG. 4 is a side view of the third embodiment.

FIG. 5 is a side view of the fourth embodiment.

FIG. 6 is a side view of a fifth embodiment.

FIG. 7 is a side view of a sixth embodiment.

FIG. 8 is a side view of a conventional fuel pump coupling device.

FIG. 9 is a front view illustrating a problem of the conventional fuel pump of the above.

FIG. 10 is a side view illustrating a problem of the conventional fuel pump of the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pump shaft 2 Pump shaft insertion hole 3 Coupling body 4,5 Key 6,7 Pin hole 8 Coupling 9,10 Pin 11 Camshaft 13,14 Keyway 15,16 Stopper

Claims (9)

[Claims] 1. A coupling device for connecting a drive shaft end of a rotary device to a drive shaft end on a drive source side, wherein an outer periphery of a cylindrical coupling body having an insertion hole for the drive shaft is formed. A coupling is provided in which keys are projected from two opposing positions on the surface in a direction perpendicular to the axis, and pin holes are formed through two opposing positions orthogonal to the direction in which the keys extend on the coupling body wall. On the other hand, at two opposing positions on the outer peripheral surface of the drive shaft end of the rotary device, a pin that projects in the direction perpendicular to the axis and is inserted into the pin hole is attached, and the drive shaft end on the drive source side A coupling device having a configuration in which a concave portion is formed on an end surface of the coupling device, and a key groove into which the key is inserted and meshed is formed at two opposing positions of an end wall around the concave portion. Drive shaft outer peripheral surface of the rotating device and drive A coupling device for a rotating device, wherein a clearance at a position corresponding to each key protruding position of a coupling among clearances between inner peripheral surfaces of a shaft insertion hole is formed smaller than clearances at other positions. 2. A drive shaft insertion hole of a rotating device of the coupling is formed in a substantially circular shape, and a portion corresponding to each key protruding position on an inner peripheral surface of the insertion hole is formed in a flat surface. The coupling device for a rotary device according to claim 1. 3. A drive shaft insertion hole of a rotary device of the coupling is formed in a substantially rectangular shape, and two long sides of the insertion hole are set on a side corresponding to each key protruding position of the coupling.
2. The coupling device for a rotary device according to claim 1, wherein the two short sides are on the side corresponding to each pin projecting position of the drive shaft of the rotary device. 4. A coupling device for connecting an end of a drive shaft of a rotary device to an end of a rotary shaft on a drive source side, wherein an outer periphery of a cylindrical coupling body having an insertion hole for the drive shaft is formed. A coupling is provided in which keys are projected from two opposing positions on the surface in a direction perpendicular to the axis, and pin holes are formed through two opposing positions orthogonal to the direction in which the keys extend on the coupling body wall. On the other hand, at two opposing positions on the outer peripheral surface of the drive shaft end of the rotary device, a pin that projects in the direction perpendicular to the axis and is inserted into the pin hole is attached, and the drive shaft end on the drive source side A coupling device having a configuration in which a concave portion is formed on an end surface of the coupling device and a key groove into which the key is inserted and meshed is formed at two opposing positions of an end wall around the concave portion. Base end of each key of the coupling A coupling device for a rotating device, characterized in that a weak portion is provided on a rear surface of the surface facing the inner surface of the key groove in the direction of rotation of the rotation axis on the drive source side. 5. The coupling device for a rotating device according to claim 4, wherein the weak portion is formed by providing a groove on a rear surface of the drive source side in the direction of rotation of the rotating shaft. 6. The thickness of the fragile portion from the central axis of the base end of each key of the coupling to the rear surface in the direction of rotation of the drive source side in the direction of rotation of the drive source is opposite to the thickness of the opposite surface. 5. The coupling device for a rotating device according to claim 4, wherein the coupling device is formed by making the size smaller. 7. A stopper protruding laterally of the key at a position distal to the fragile portion on both surfaces opposite to the inner surfaces on both sides of the key groove at the base end of each key of the coupling. The coupling device for a rotating device according to any one of claims 4 to 6, wherein a length between both end surfaces of the stoppers is formed larger than an inner width of the key groove. 8. A coupling device for connecting an end of a drive shaft of a rotary device to an end of a rotary shaft on a drive source side, the outer periphery of a cylindrical coupling body having an insertion hole for the drive shaft. A key is projected from two opposing positions on the surface in the direction perpendicular to the axis, and a pin hole is formed at two opposing positions orthogonal to the direction in which the key extends on the coupling body wall. On the other hand, at two opposing positions on the outer peripheral surface of the drive shaft end of the rotary device, a pin that projects in the direction perpendicular to the axis and is inserted into the pin hole is attached, and the drive shaft end on the drive source side A coupling device having a configuration in which a concave portion is formed on an end surface of the coupling device and a key groove into which the key is inserted and meshed is formed at two opposing positions of an end wall around the concave portion. Face the inner surface of each keyway of each key A rotating device characterized in that a rear side surface of the rotating shaft on the drive source side in the direction of rotation of the drive source side is formed as a tapered surface such that the key thickness decreases from the base end to the distal end. Coupling device. 9. The invention according to claim 8, wherein, instead of the tapered surface of the side surface of each key of the coupling facing the inner surface of each key groove, the rear side surface of the key on the drive source side in the direction of rotation of the rotary shaft. A rotating device characterized in that a tapered surface is formed on the inner surface of the key groove facing the surface such that the inner width of the key groove increases from the portion corresponding to the base end portion to the portion corresponding to the distal end portion of each key. Coupling device.