JP2000130458A - Universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a universal joint accurately operated over a long period by making a yoke slidable in an axial direction of a pin and smoothly rotating/ sliding the yoke relative to the pin. SOLUTION: In a universal joint having a pin hole in four directions at a right angle to each other in one plane by inserting in the intermediate between a pair of hubs 1, 2, driving a pin 4 into this pin hole and providing a block body 3 engaged with a yoke through the pin 4, a thin plate layered dynamic pressure bearing 5 is inserted in a clearance between the pin 4 driven into the block body 3 and the pin hole of the yoke engaged therewith.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft coupling attached to a drive shaft, and more particularly, to a small universal joint which transmits a rotational force by allowing a drive shaft and a driven shaft to bend.

[0002]

2. Description of the Related Art A universal joint (also referred to as a universal joint or a universal shaft joint) is a type of a shaft joint attached to a drive shaft. The universal joint generates torque when the drive shaft and the driven shaft are bent around the shaft joint. It is known for its ability to transmit power, and is widely used in the driving parts of various industrial machines, including automobiles.

FIGS. 5 and 6 show an example of a conventionally known universal joint disclosed in Japanese Patent Application Laid-Open No. 3-74632. As shown in FIG. 5 showing the assembled state and FIG. 6 showing the disassembled state of the parts, one set of universal joints includes a pair of hubs 1 and 2 attached to ends of a drive shaft and a driven shaft. A block body 3 inserted in the middle of these and engaged with the pair of hubs 1 and 2
It consists of.

[0004] At the tips of the hubs 1 and 2, yokes 11 and 21 are provided at diametrically opposed positions, respectively. On the other hand, the block body 3 is, for example, a rectangular parallelepiped in which a pair of faces facing the hubs 1 and 2 has a square rectangular parallelepiped, and has a pin hole perpendicular to the center of four faces other than the square faces of the rectangular parallelepiped. That is, it has pin holes that open in four directions perpendicular to each other in the same plane, and engages with the yokes 11 and 21 via the pins 4 driven into the pin holes.

If the yokes 11, 21 are arranged on both sides of the block body 3 so as to be at right angles to each other, and the pins 4 are driven into the pin holes, the yokes 11, 21 are engaged with the block body 3.
Since the hubs 1 and 2 can rotate freely with respect to the orthogonal axis formed by the four pins 4, the hub 1 to the block body 3 to the hub 2 can be bent while allowing the drive shaft and the driven shaft to bend. Rotational force is transmitted between them.

The yoke 11, with respect to the pin 4,
In order to make the rotation of 21 smooth, in a large universal joint, the pin holes of the yokes 11 and 21 are made larger than the diameter of the pin 4 and the rolling bearing is inserted into the gap between the pin holes of the yokes 11 and 21 and the pin 4. Is common, for example,
In Japanese Patent Application Laid-Open No. 56556/1995 and Japanese Utility Model Application Laid-Open No. 57-35520, it is proposed to insert a needle roller bearing.

However, for example, in a small universal joint having a shaft diameter of about 8 to 10 mm, there is no so-called miniature bearing-class small product in the needle bearing.
Further, the needle bearing cannot be adopted because it has a drawback that it cannot absorb the axial backlash due to its structure. Therefore, in the case of a small universal joint, as described in Japanese Patent Application Laid-Open No. 3-74632, the yokes 11, 21
It has been proposed to insert a molded product of self-lubricating fluororesin or the like or a bush 6 lined with these on the surface in a gap between the pin hole and the pin 4. The bush 6 is worn due to the rotation and sliding of the yokes 11 and 21 with respect to, and there is a problem that play occurs between the pin 4 and the bush 6. For this reason,
In the case of a precision machine or the like, for example, the backlash at the time of reverse rotation increases, which may cause a malfunction. Therefore, it is necessary to replace the bush 6 and remove the play by overhaul.

On the other hand, Japanese Unexamined Patent Publication No. 9-79281 discloses that the pin 4 is inserted into the gap between the pin hole of the yokes 11 and 21 and the pin 4 in order to smoothly rotate the yokes 11 and 21 with respect to the pin 4. It has been proposed to insert a ball bearing by applying a preload in the axial direction. However, this universal joint has a problem that the yokes 11, 21 cannot slide in the axial direction of the pin 4.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art by providing yokes 11, 21
Is slidable in the axial direction of the pin 4, the yoke 11, 21 can be smoothly rotated and slid with respect to the pin 4, and there is no wear between members due to the use of the universal joint, and accurate for a long time. It is to propose a universal joint that operates.

[0010]

According to the first aspect of the present invention, a pair of diametrically open yokes 11 and 21 are provided at the distal end, and a pair of yokes 11 and 21 are attached to ends of a drive shaft and a driven shaft. Hubs 1 and 2, inserted between the pair of hubs 1 and 2, having pin holes in four directions perpendicular to each other in one plane,
The yoke 1 is inserted through a pin 4 driven into the pin hole.
1. A universal joint comprising a block body 3 engaged with a block 21 and an annular thin plate formed in a gap between a pin 4 driven into the block body 3 and pin holes of yokes 11 and 21 engaged with the block body 3. Annular laminated hydrodynamic bearing (hereinafter, referred to as an annular laminated laminated member having a lubricant and an annular laminated laminated member in which
This is called a thin-plate laminated hydrodynamic bearing. And (5) a universal joint having 5 inserted therein.

The invention according to a second aspect is characterized in that the yoke 11,
A gap is provided between the block body 3 and the yoke
When the ends 11 and 21 come into contact with the block body 3, the ends of the pins 4 that slide on the yokes 11 and 21 facing the yokes 11 and 21 that come into contact with the block body 3 are in the thin-plate laminated dynamic pressure bearing 5. ,
The universal joint according to claim 1, wherein the pin (4) has a length protruding from the block body (3).

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front view showing a partial section of a small universal joint of the embodiment, and FIG. 2 is a side view of the same. Reference numerals 1 and 2 denote hubs attached to the drive shaft and the driven shaft, 11 and 21 denote a pair of opposed jaws in the form of jaws formed at the tips of the hubs 1 and 2, 3 denotes a block body, and 4 denotes a pin. The hubs 1 and 2 and the yokes 11 and 21 are the same as those described with reference to FIGS.

In the present invention, a small thin-plate laminated hydrodynamic bearing is provided in the gap between the pin 4 driven into the block body 3 and the pin hole of the yoke (11, 21) engaged with the block body 3 instead of the conventional bush 6. 5 has been inserted. Further, in the present invention, the block body 3 is formed in a cylindrical shape, a gap is provided between the block body 3 and the yoke 11, 21, and the protruding length of the pin 4 protruding from the block body 3 is determined by the yoke 11, 21 contacting the block body 3. At this time, the end of the pin 4 that slides on the yoke opposite to the contacted yoke is located inside the thin-plate laminated hydrodynamic bearing 5.

As shown in FIG. 3, which shows a schematic plan view, the thin-plate laminated hydrodynamic bearing 5 is made of a specially shaped thin plate component called a shaft guide 7 having a plurality of projections 7a formed on the inner periphery of a ring. The upper and lower portions of the laminated body in the thickness direction are sandwiched between seals, and are mounted in a case together with a lubricant, for example, grease 8. The shape of one convex portion 7 a of the shaft guide 7 is inserted into the laminated laminated hydrodynamic bearing 5. As shown in FIG. 4, which is shown together with the pin 4, the gap with the pin 4 is the narrowest at the center of the projection 7 a of the shaft guide 7, and the gap on both sides is widened. The dimensional accuracy of the inner diameter of the laminated laminated hydrodynamic bearing 5 is as high as 0 to +3 μm.

By setting the inner diameter of the laminated laminated hydrodynamic bearing to a plus tolerance of 3 μm or less than the outer diameter of the pin 4, when the universal joint is rotated at a high rotational speed, the pin 4 and the shaft guide are rotated. 7 convex portion 7a
The pressure due to the squeezing action can be effectively generated in the grease between them, and the pin 4 is supported via the grease 8 without contacting the projection 7a of the shaft guide 7.

Therefore, since the clearance between the pin 4 and the thin-plate laminated dynamic pressure bearing 5 formed by laminating the shaft guides 7 is set to a plus tolerance of 3 μm or less, the frictional resistance becomes extremely small because the clearance is small. The yokes 11, 21 to which the thin-plate laminated dynamic pressure bearings 5 are attached have extremely small backlash with respect to the pins 4, and the rotation and sliding are smooth.

Further, a gap is provided between the block body 3 and the yokes 11, 21 so that even if the yokes 11, 21 slide to the limit in the axial direction of the pins 4, the ends of the pins 4 are laminated thin-plate hydrodynamic bearings. Since the pins 4 have a protruding length within the range of 5, the yokes 11, 21 can move smoothly in the axial direction of the pins 4. In this way, when there is eccentricity where the axis of the drive shaft and the axis of the driven shaft do not intersect, two universal joints are required to transmit the rotational force, but one universal joint is required. Since the rotational force can be transmitted by the joint, it can be applied to a place where the installation space is limited, and the structure is simplified and the cost can be reduced.

The procedure for assembling the universal joint according to the present invention is as follows. The laminated laminated hydrodynamic bearing 5 is mounted in the through holes provided in the yokes 11 and 21, and the inner diameter hole of the laminated laminated hydrodynamic bearing 5, the block body 3 and The holes may be aligned with each other, and the pins 4 may be driven in from outside to engage the hubs 1 and 2 having the pair of yokes 11 and 21 with the block body 3.

In the small universal joint of the present invention assembled as described above, for example, the shaft diameter of the hub part is 5 mm, the maximum diameter of the yoke part is 25 mm, the inner diameter of the thin laminated laminated hydrodynamic bearing to be inserted is 3 mm, and the outer diameter is 7 mm. It was able to rotate without any problem up to 10,000 rpm, endured higher rotation than ball bearings, and had lower operating noise. Further, since the grease 8 is filled in the thin-plate laminated hydrodynamic bearing 5, it can be used without lubrication for a long time without lubrication.
Maintenance or unnecessary.

In the above description, the block body 3 has a cylindrical shape, but the present invention is not limited to this.

[0021]

According to the present invention, the yokes 11, 21 are connected to the pins 4
Can be slid in the axial direction, and the yoke 1
A universal joint that can smoothly rotate and slide 1, 21 is obtained. In addition, the yoke 11,
Since the frictional resistance of 21 is extremely small, there is an excellent effect that a universal joint that can perform high-speed rotation, does not generate noise and wear of members, and performs accurate operation for a long time can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view partially showing a cross section of a universal joint according to an embodiment of the present invention.

FIG. 2 is a side view showing a partial cross section of the universal joint according to the embodiment of the present invention.

FIG. 3 is a plan view showing a shaft guide of the thin-plate laminated hydrodynamic bearing used in the embodiment of the present invention.

FIG. 4 is an explanatory diagram for explaining the operation of the thin-plate laminated hydrodynamic bearing used in the embodiment of the present invention.

FIG. 5 is a front view showing a universal joint according to a conventional technique in a partial cross section.

6 is a perspective view showing the universal joint of FIG. 5 in an exploded state.

[Explanation of symbols]

 1, 2 hub 3 block body 4 pin 5 annular thin-plate laminated dynamic pressure bearing (thin-plate laminated dynamic pressure bearing) 6 bush 7 shaft guide 7a convex part 8 grease (lubricating oil) 11, 21 yoke

Claims (2)

[Claims] 1. A pair of hubs (1, 2) having a pair of diametrically open yokes (11, 21) at their ends and attached to ends of a drive shaft and a driven shaft, and a pair of hubs. Pins are inserted in the middle of (1 and 2) and have pin holes in four directions perpendicular to each other in one plane, and are engaged with the yokes (11 and 21) via pins (4) driven into the pin holes. And a pin (4) driven into said block (3).
And a thin-plate laminated hydrodynamic bearing (5) inserted into a gap between the pin hole of the yoke (11, 21) engaged with the universal joint. 2. A gap is provided between the yoke (11, 21) and the block body (3), and when the yoke (11, 21) comes into contact with the block body (3), the contacted yoke is provided. The end of the pin (4) sliding on the yoke (11, 21) facing the (11, 21) protrudes from the block body (3) so as to be inside the thin-plate laminated hydrodynamic bearing (5). Universal joint according to claim 1, characterized in that it is a pin (4) having a length.