JP2004360856A - Interconnecting structure of universal joint and shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an interconnecting structure with a simple constitution which can couple a shaft end of a shaft to be coupled in a yoke having a substantially U shaped section of a universal joint without unevenness. <P>SOLUTION: The interconnecting structure of the universal joint and the shaft includes a tapered section 51 for reducing a diameter toward a tip on the way of the clamping bolt 5 for clamping two side plates 35, 35 of the yoke 30 having the substantially U shaped section at a position separate from a bottom plate 36. A retaining surface 13 inclined in a tapered state oppositely to a bolt hole 37 at an insertion side of the clamping bolt 5 is provided at a shaft end 10 engaged between the two side plates 35 and 35 of the yoke 30. The diameter reduced part 51 is brought into contact with the retaining surface 13 at the clamping bolt 5 clamping time, and the shaft end 10 is pushed to the bottom plate 36. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a connection structure between a universal joint and a shaft used to connect two shafts whose shaft centers cross or are eccentric so as to be able to transmit rotation.
[0002]
[Prior art]
A universal joint (universal joint) faces a pair of yokes provided on one side with a fork-shaped pin receiving arm branched into two branches so that respective pin receiving arms cross at a substantially right angle. This is a known mechanical element in which the ends of arms are connected by a cross-shaped cross pin, and is used in many industrial fields to connect two axes whose axes are crossed or eccentric so that rotation can be transmitted.
[0003]
Such a universal joint is used, for example, in a steering device of a vehicle to connect a steering shaft that rotates in response to operation of a steering wheel as a steering member and an input shaft of a steering mechanism. The input shaft and the input shaft are separately mounted inside and outside the vehicle compartment, and it is required that the respective yokes be retrofitted to the shaft ends of the steering shaft and the input shaft whose axial length direction is fixed. You. Therefore, a universal joint having at least one yoke having a substantially U-shaped cross section in which one side of two opposing side plates is connected by a bottom plate is used (for example, see Patent Documents 1 and 2).
[0004]
FIG. 6 is an explanatory diagram of this type of connection structure between a yoke and a shaft. As shown in the figure, the yoke 60 has a substantially U-shaped cross section in which one side of two side plates 61 facing each other is connected by an arched bottom plate 62 and the other side is open. Bolt holes 63, 63 penetrating in the thickness direction are formed in the side plates 61, 61 at positions away from the bottom plate 62.
[0005]
The shaft 7 connected to the yoke 60 has two contact surfaces 71, 71 that can be fitted between the side plates 61, 61, an arch surface 72 connecting one side thereof, and the other side. 6A, and is fitted from the opening side between the side plates 61 of the yoke 60 as shown by arrows in FIG. 6A, and shown in FIG. 6B. As described above, the arch surface 72 is brought into contact with the inner surface of the bottom plate 62, the fixing bolt 8 is passed through the bolt holes 63, 63 from outside the one side plate 61, and the fixing bolt 8 protrudes outside the other side plate 61. Are connected by tightening a tightening nut 80 to the threaded portion of.
[0006]
This connection is realized by fitting the yoke 60 from the outside in the radial direction of the shaft 7, so that it can be retrofitted to the shaft 7 whose axial position is fixed. The shaft 7 fitted between the side plates 61 of the yoke 60 is fixed to the inner surfaces of the side plates 61, 61 approaching by tightening the fixing bolts 8 by pressing the contact surfaces 71, 71.
[0007]
[Patent Document 1]
JP-A-10-9281 [Patent Document 2]
JP-A-9-79279
[Problems to be solved by the invention]
However, in the above connection structure, since the fastening of the fixing bolt 8 is performed on the opening side of the side plates 61, 61, near the bottom plate 62 located away from the fastening portion, as shown in FIG. , between the contact surface 71, 71 of the inner surface and the shaft 7 of 61, there is a case where a gap [delta] ₁ reserved for fitting remains.
[0009]
In the above connection structure, the movement of the shaft 7 to the opening side of the side plates 61 is restricted by the fixing bolt 8 abutting on the pressing surface 73, but between the fixing bolt 8 and the pressing surface 73. since the predetermined gap [delta] ₂ to the easy insertion of the fixing bolt 8 is secured, as shown in FIG. 6 (b), after the tightening of the fixing bolts 8, between the fixing bolts 8 and the pressing surface 73 in some cases the gap [delta] ₂ remains.
[0010]
When the connection is made in a state where the gaps δ ₁ and δ ₂ are generated in this way, the rotating shaft 7 in this state rattles inside the yoke 60, and a rattling sound is generated due to the collision between the two. When applied to a steering device of a vehicle as described above, the backlash effect occurs in the transmission from the steering wheel to the steering mechanism. The problem of inviting it occurs.
[0011]
In order to solve such a rattling problem, in Japanese Patent Application Laid-Open No. H11-163, the facing distance between the side plates 61, 61 is increased toward the opening side, and the thickness of the side plates 61, 61 is further reduced by connecting the bottom plate 62 and the connecting portion. The thickness is reduced in the vicinity, so that the clamping of the shaft 7 between the side plates 61, 61 by the tightening of the fixing bolts 8 proceeds from the side of the bottom plate 62 toward the opening side. configuration which aimed to eliminate the gap [delta] ₁ occurring between the contact surface 71, 71 is employed. However, in this configuration, on difficult facing distance and optimization of the thickness of the thin portion of the side plates 61 and 61, it is impossible to eliminate the gap [delta] ₂ between the fixing bolts 8 and the pressing surface 72, sufficient The effect of preventing backlash cannot be obtained.
[0012]
Also, in Patent Document 2, a fixing bolt 8 having a cam portion in the middle of the shaft length direction is used, and after the fixing bolt 8 is inserted through the side plates 61, 61 and then rotated around the axis, the cam portion of the shaft 7 is rotated. pressed against the pressing face 73, is employed configuration which aimed to eliminate the gap [delta] ₂ produced between the fixing bolts 8 and the pressing surface 7. However, in this configuration, a special fixing bolt 8 having a cam portion is required, and it takes time to set the rotational position of the fixing bolt 8 at the time of assembly in order to optimize the pressing strength of the cam portion. , it is not possible to eliminate the gap [delta] ₁ occurring between the contact surface 71, 71 and side plates 61 and 61, sufficient effect of preventing looseness can not be obtained.
[0013]
The present invention has been made in view of such circumstances, and has a simple configuration that enables a shaft end portion of a shaft to be connected to be connected without play in a yoke having a substantially U-shaped cross section of a universal joint. It is an object of the present invention to provide a connection structure.
[0014]
[Means for Solving the Problems]
The connection structure between the universal joint and the shaft according to the first invention of the present invention is to be connected to a universal joint including a yoke having a substantially U-shaped cross section formed by connecting one side of two opposing side plates by a bottom plate. In order to connect the shaft, the shaft end of the shaft is fitted between the side plates of the yoke via the opening on the other side, and a fixing bolt penetrating the side plate at a position away from the bottom plate is tightened between the side plates. In the connection structure between the universal joint and the shaft for clamping and fixing, a reduced diameter portion that reduces the diameter toward the tip can be brought into contact with the reduced diameter portion on the outer surface of the shaft end of the shaft in the middle of the fixing bolt. The pressing surface is inclined toward the bottom plate of the yoke by the reduced diameter portion in accordance with tightening of the fixing bolt.
[0015]
In the present invention, the reduced diameter portion provided in the middle of the fixing bolt penetrating the side plate of the yoke is brought into contact with the pressing surface provided on the outer surface of the shaft end portion, and the fixing bolt is tightened in this state, and the pressing is performed by the reduced diameter portion. Press the surface toward the bottom plate, and clamp the shaft end, which is clamped from both sides by the side plate of the yoke, between the reduced diameter portion of the fixing bolt and the bottom plate of the yoke in a direction crossing the direction of the clamping. Press to eliminate backlash of the shaft end in the yoke.
[0016]
The connection structure between the universal joint and the shaft according to the second invention of the present invention is to be connected to a universal joint including a yoke having a substantially U-shaped cross section formed by connecting one side of two opposing side plates by a bottom plate. In order to connect the shaft, the shaft end of the shaft is fitted between the side plates of the yoke via the opening on the other side, and a fixing bolt penetrating the side plate at a position away from the bottom plate is tightened between the side plates. In the coupling structure between the universal joint and the shaft for clamping and fixing, a pressing surface protruding toward the opening side of the yoke is provided on the outer surface of the shaft end of the shaft, and a middle part of the fixing bolt is provided on the pressing surface. The pressing surface is pressed toward the bottom plate of the yoke in accordance with tightening of the fixing bolt.
[0017]
In the present invention, the middle part of the fixing bolt penetrating the side plate of the yoke is brought into contact with the pressing surface of the shaft end portion which is convex toward the opening side between the side plates of the yoke, and the bottom plate of the yoke is attached to the pressing surface. The yoke is pressed against the shaft end, which is clamped from both sides by the side plate of the yoke, between the middle part of the fixing bolt and the bottom plate of the yoke in a direction crossing the direction of the compression. Eliminates backlash at the shaft end inside. The contact between the fixing bolt and the holding surface occurs as substantial point contact near the vertex of the holding surface, and does not hinder the insertion of the fixing bolt.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments. FIG. 1 is an explanatory diagram of a use state of a universal joint in a vehicle steering system. In the figure, reference numeral 1 denotes a steering shaft which rotates in response to operation of a steering wheel as a steering member, and 2 denotes an input shaft for inputting rotation to a steering mechanism (for example, a pinion of a rack and pinion type steering mechanism). Axis). The steering shaft 1 extends downward from a steering wheel positioned inside the vehicle compartment, and the input shaft 2 extends upward from a steering mechanism fixedly supported outside the vehicle compartment. As shown in the figure, an intermediate shaft 4 having universal joints 3 at both ends is used to connect the shaft ends 10 and 20 of the steering shaft 1 and the input shaft 2 which face each other with the shaft centers crossed and eccentric. ing.
[0019]
The universal joints 3, 3 are provided with a pair of yokes 30, 31, respectively, in which fork-shaped pin receiving arms 32, 33 branched into two branches are provided on one side, and these yokes 30, 31 are respectively connected to the respective pin receiving members. The arms 32, 33 face each other so as to intersect at a substantially right angle, and the ends of both arms 32, 33 are connected by a cross-shaped cross pin 34.
[0020]
In such universal joints 3, one cylindrical yokes 31, 31 are externally fitted and fixed to both ends of the intermediate shaft 4, respectively, and are integrated with the intermediate shaft 4. The connection of the steering shaft 1 and the input shaft 2 by the intermediate shaft 4 is performed by connecting the yokes 30, 30 on the other side of the universal joints 3, 3 at both ends, as shown by arrows in FIG. 10 and the shaft end 20 of the input shaft 2 are respectively fitted from the outside in the radial direction and are held separately. In order to realize such connection without play, the yokes 30, 30, and The shaft ends 10, 20 have the following characteristic configuration.
[0021]
FIG. 2 is a perspective view of a connecting portion between the yoke 30 of the universal joint 3 and a shaft (the steering shaft 1 in the figure). As shown in the drawing, the yoke 30 has a substantially U-shaped cross-sectional shape in which one side of two side plates 35, 35 which are substantially parallel to each other are connected by a bottom plate 36 which is curved in an arch shape, and the other side is open. ing. Bolt holes 37, 38 are formed in the side plates 35, 35 at positions facing away from the bottom plate 36 and penetrating in the thickness direction, respectively.
[0022]
The shaft end 10 of the steering shaft 1 connected to such a yoke 30 includes two flattened contact surfaces 11, 11 that can be fitted between the side plates 35, 35. One side of the contact surfaces 11, 11 is connected to the arch surface 12 which is curved in an arch shape corresponding to the bottom plate 36 of the yoke 30, and the other side is also tapered to a substantially half in the width direction. It has a cross-sectional shape as shown in the figure communicating with the holding surface 13.
[0023]
The connection between the shaft end 10 and the yoke 30 is performed by first connecting the yoke 30 and the shaft end 10 to each other by opening the side plate 35 between the side plates 35 as shown in FIG. After the yoke 30 has been positioned so as to face the arch surface 12 and the yoke 30 has been fitted to the shaft end 10 so that the abutment surfaces 11 and 11 of the former fit along the inner surfaces of the side plates 35 and 35, respectively. The fixing bolt 5 is passed through the bolt holes 37 and 38 provided in the side plates 35 and 35 from the outside of the one side plate 35, and the fastening nut 50 is screwed into the screw portion of the fixing bolt 5 protruding outside the other side plate 35. By tightening, it is realized as shown in FIG.
[0024]
The fixing bolt 5 used for such a connection has a tapered diameter at a substantially central portion in the axial direction, which has a slope corresponding to the pressing surface 13 of the shaft end 10 and is tapered toward the tip. A screw portion 52 having a thread formed on the outer periphery is continuously provided on the distal end side of the reduced diameter portion 51. A bolt hole 37 provided in one side plate 35 of the yoke 30 is a large-diameter hole through which the base of the fixing bolt 5 can be inserted, and a bolt hole 38 provided in the other side plate 35 has a small-diameter screw portion 52. The fixing bolt 5 is inserted from the side of the large-diameter bolt hole 37.
[0025]
FIG. 3 is an explanatory view of the coupling structure shown in FIG. 2. FIG. 3A shows a state before the fixing bolt 5 is tightened, and FIG. 3B shows a state after the fixing bolt 5 is tightened. Is shown.
[0026]
As described above, the fitting of the shaft end portion 10 between the side plates 35, 35 of the yoke 30 is performed with the contact surfaces 11, 11 provided on the shaft end portion 10 along the side plates 35, 35. As shown in FIG. 3 (a), the rear contact surfaces 11, 11 face the inner surfaces of the side plates 35, 35 of the yoke 30 with a slight gap required for fitting. Further, at this time, the arch surface 12 connecting one side of the contact surfaces 11, 11 is brought into contact with the bottom plate 36 of the yoke 30, and the pressing surface 13 connecting the other side has a tapered part in the middle with a large-diameter bolt. It is in a state of facing the hole 37 side.
[0027]
Insertion of the fixing bolt 5 is performed in this state, and as shown in FIG. 3A, the reduced diameter portion 51 of the fixing bolt 5 comes into contact with the pressing surface 13 facing the bolt hole 37, and 5 is protruded to the outside of the side plate 35 on the same side through the small-diameter bolt hole 38, and a tightening nut 50 is screwed into the screw portion 52 and tightened. ) Is obtained.
[0028]
At this time, the side plates 35, 35 of the yoke 30 reduce the facing width by tightening the fixing bolts 5, and serve to clamp the contact surfaces 11, 11 of the shaft end 10 from both sides. At the same time, the reduced diameter portion 51 of the fixing bolt 5 is pressed against the pressing surface 13 of the shaft end portion 10 that comes into contact with the fixing bolt 5, and has an action of pressing the pressing surface 13 in a direction indicated by an outline arrow in the drawing. Eggplant Therefore, the shaft end 10 is pressed from both right and left sides by the side plates 35 and 35 of the yoke 30, and is pressed from both upper and lower sides by the reduced diameter portion 51 of the fixing bolt 5 and the bottom plate 36 of the yoke 30. As shown in FIG. 3B, a fixed state is obtained in which one contact surface 11 is in close contact with the inner surface of the side plate 35 on the same side, and the arch surface 12 is in close contact with the inner surface of the bottom plate 36 that is continuous with the side plate 35.
[0029]
The shaft end 10 connected in this manner can rotate integrally with the yoke 30 without rattling in any of the vertical and horizontal directions. This connection can be easily performed by simple tightening of the tightening nut 50 to the screw portion 52 of the fixing bolt 5, and good connection without backlash can be achieved without controlling the tightening load with high precision. You.
[0030]
The inclination angle of the reduced diameter portion 51 of the fixing bolt 5 is desirably set to be as small as possible in order to direct the direction of the pressing force applied to the holding surface 13 toward the bottom plate 36. The magnitude of the pressing force generated as a component of the tensile force applied in the axial direction of the fixing bolt 5 by tightening the nut 50 is reduced. For these reasons, the inclination angle needs to be set in consideration of the magnitude and direction of the required pressing force. As shown in FIG. 3, when the inclination angle is set so that the pressing force acts toward the vicinity of the boundary between the side plate 35 and the bottom plate 36, the shaft end 10 is pressed toward the bottom plate 36 with an appropriate force. And a good rattling prevention effect can be obtained.
[0031]
The reduced diameter portion 51 of the fixing bolt 5 having the above-described action is reduced in diameter coaxially toward the distal end, and can be formed with high precision by processing using a general-purpose machine tool. Further, the holding surface 13 provided on the shaft end 10 can also be easily formed as an inclined surface having a predetermined angle, and the connection structure described in the above embodiment can be realized without special processing. Is possible.
[0032]
FIG. 4 is a perspective view showing another embodiment of the connecting portion between the yoke 30 and the shaft of the universal joint 3. The configuration of the connecting portion shown in this drawing is the same as that of FIG. 2 except for the configuration of the fixing bolt 5 and the configuration of the shaft end portion 10. Corresponding portions are denoted by the same reference numerals, and detailed description is omitted. .
[0033]
The shaft end 10 is provided with flattened contact surfaces 14, 14 having two surface widths capable of being fitted between the side plates 35, 35 of the yoke 30, and one of these contact surfaces 14, 14. The sides are connected by an arch surface 15 having a curved shape corresponding to the bottom plate 36 of the yoke 30, and the other side is connected by a presser surface 16 having a convex curved shape having a top portion at a substantially center. It has such an oval cross-sectional shape.
[0034]
The fixing bolt 5 includes a large-diameter holding portion 53 that is continuous with the head portion, and a small-diameter screw portion 54 that is continuously provided on the distal end side of the holding portion 53 and has a thread on the outer periphery. One of the bolt holes 37 provided in the side plates 35 of the 30 is a large-diameter hole through which the holding portion 53 can be inserted, and the other bolt hole 38 is a small-diameter hole through which the screw portion 54 can be inserted. .
[0035]
The connection between the shaft end portion 10 and the yoke 30 as described above is performed by connecting the yoke 30 to the shaft end portion 10 and the inner contact surfaces of the former side plates 35, 35 as shown by arrows in FIG. 13 and 13 are fitted from the side of the arch surface 15 so as to extend, and then the fixing bolt 5 is passed through the bolt holes 37 and 38 provided in the yoke 30 side plates 35 and 35 from the side of the large-diameter bolt hole 37. As shown in FIG. 4B, this is realized by screwing a tightening nut 50 into a screw portion 54 protruding to the outside of the side plate 35 through the small-diameter bolt hole 38.
[0036]
5A and 5B are explanatory views of the connection structure shown in FIG. 4. FIG. 5A shows a state in which the fixing bolt 5 is being inserted, and FIG. 5B shows a state after the fixing bolt 5 is tightened. Is shown.
[0037]
As shown in FIG. 5 (a), the fitting of the shaft end 10 into the yoke 30 is performed by bringing the contact surfaces 14, 14 on both sides of the shaft end 10 into opposition to the inner surfaces of the side plates 35, 35 of the yoke 30. The arch surface 15 which connects one side of the abutment 14 is brought into contact with the bottom plate 36 of the yoke 30. At this time, the pressing surface 16 which connects the other side of the abutment surfaces 14 and 14 has a top projecting to the center. Is substantially aligned with the lower edge of the large-diameter bolt hole 37 formed in the side plate 35 on one side.
[0038]
The insertion of the fixing bolt 5 is performed in this state. The screw portion 54 at the tip of the fixing bolt 5 has a smaller diameter than the bolt hole 37 corresponding to the holding portion 53, and passes through a predetermined gap from the top of the holding surface 16 as shown in FIG. And is inserted into the other bolt hole 38. On the other hand, the large-diameter pressing portion 53 continuous with the screw portion 54 comes into contact with the vicinity of the vertex of the pressing surface 16, and a pressing force is applied to the pressing surface 16 by the subsequent pushing of the fixing bolt 5, and the shaft end portion is pressed. 10 is urged toward the bottom surface 36 of the yoke 30. The pressing portion 53 of the fixing bolt 5 is substantially in point contact with the vicinity of the vertex of the pressing surface 16, and the pressing of the fixing bolt 5 while applying the pressing force can be easily performed with a small resistance. Can be performed.
[0039]
The connection of the shaft end 10 to the yoke 30 is shown in FIG. 5B by tightening a tightening nut 50 on a screw portion 54 of a fixing bolt 5 protruding outside the side plate 35 on the same side through a bolt hole 38. It is realized as follows. At this time, the opposing width of the side plates 35, 35 of the yoke 30 is reduced by tightening the fixing bolts 5, and the upper portions of the contact surfaces 14, 14 are pressed from both sides. At the same time, the fixing bolt 5 is displaced toward the bottom plate 36 in accordance with the decrease in the opposing width of the side plates 35, 35 of the yoke 30, and the pressing portion 53 of the fixing bolt 5 presses the shaft end 10 in contact with this. The pressing surface 16 is pressed against the bottom plate 36 of the yoke 30 as shown by an outline arrow in the drawing. As a result, the shaft end 10 is clamped from both left and right sides by the side plates 35 of the yoke 30, and is also clamped from both upper and lower sides by the holding portion 53 of the fixing bolt 5 and the bottom plate 36 of the yoke 30. It is connected and can rotate integrally with the yoke 30 without rattling in any of the vertical and horizontal directions.
[0040]
This connection can be easily realized by simple fastening of the fixing bolt 5 and the fastening nut 50. The fixing bolt 5 may be a general bolt in which a screw portion 54 having a diameter slightly smaller than the pressing portion 53 is continuously provided on the tip side of the pressing portion 53 having a predetermined outer diameter. The pressing surface 16 to be provided can be formed simply and with high precision as a portion remaining after forming the contact surfaces 14, 14 by flattening a shaft having a circular cross section with a predetermined two-surface width, for example. The connection structure described in the above embodiment can be realized without requiring special processing.
[0041]
In the steering device shown in FIG. 1, the connection between the shaft end 20 of the input shaft 2 and the yoke 30 of the universal joint 3 on the same side is also realized by the connection structure shown in FIGS. 2 and 3, or FIGS. In such a connected steering device, the rotation transmission from the steering shaft 1 to the input shaft 2 via the intermediate shaft 4 causes generation of rattling noise and response delay due to rattling. This operation is performed without any occurrence, and a good steering feeling can be obtained.
[0042]
In the above embodiment, an example of application to a steering device of a vehicle has been described. However, a connection structure between a universal joint and a shaft according to the present invention includes a universal joint including a yoke having a substantially U-shaped cross section and a shaft. It is needless to say that the present invention can be applied to all uses that require connection without play, and the same effect can be obtained.
[0043]
【The invention's effect】
As described in detail above, in the joint structure of the universal joint and the shaft according to the present invention, the shaft end of the shaft which is fitted into the yoke having a substantially U-shaped cross section of the universal joint and clamped between the side plates by tightening the fixing bolts. The part is clamped between the bottom plate of the yoke and the fixing bolt with a simple structure, effectively preventing rattling, and preventing the occurrence of problems associated with rattling, enabling good transmission. Thus, the present invention has excellent effects.
[Brief description of the drawings]
FIG. 1 is an explanatory view of a use state of a universal joint in a vehicle steering system.
FIG. 2 is a perspective view of a connecting portion between a yoke and a shaft of the universal joint.
FIG. 3 is an explanatory diagram of the connection structure shown in FIG. 2;
FIG. 4 is a perspective view showing another embodiment of a connecting portion between a yoke and a shaft of a universal joint.
FIG. 5 is an explanatory diagram of the connection structure shown in FIG. 4;
FIG. 6 is an explanatory view of a conventional connection structure between a yoke and a shaft of a universal joint.
[Explanation of symbols]
1 Steering axis (axis)
2 Input shaft (axis)
3 Universal joint 5 Fixing bolt 10 Shaft end 13 Holding surface 16 Holding surface 20 Shaft end 51 Reduced diameter portion 30 Yoke 35 Side plate 36 Bottom plate 38 Groove

Claims (2)

In order to connect a universal joint having a yoke having a substantially U-shaped cross section formed by connecting one side of two opposing side plates with a bottom plate and a shaft to be connected, the shaft end of the shaft is connected to the side plate of the yoke. In the coupling structure between the universal joint and the shaft, which is fixed by pressing between the side plates by tightening fixing bolts penetrating the side plate at a position away from the bottom plate, with the other side being fitted through the opening on the other side.
In the middle of the fixing bolt, a reduced-diameter portion for reducing the diameter toward the tip is provided, and on the outer surface of the shaft end of the shaft, a pressing surface that is inclined so as to contact the reduced-diameter portion is provided, and the fixing bolt is tightened. A structure in which the pressing surface is pressed toward the bottom plate of the yoke by the reduced-diameter portion in accordance with (1). In order to connect a universal joint having a yoke having a substantially U-shaped cross section formed by connecting one side of two opposing side plates with a bottom plate and a shaft to be connected, the shaft end of the shaft is connected to the side plate of the yoke. In the coupling structure between the universal joint and the shaft, which is fixed by pressing between the side plates by tightening fixing bolts penetrating the side plate at a position away from the bottom plate, with the other side being fitted through the opening on the other side.
A pressing surface protruding toward the opening side of the yoke is provided on the outer surface of the shaft end of the shaft, and an intermediate portion of the fixing bolt is brought into contact with the pressing surface, according to the fastening of the fixing bolt. Wherein the pressing surface is pressed toward the bottom plate of the yoke.

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