JP3435854B2 - Universal joint - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention A universal joint according to the present invention is incorporated in, for example, a steering device of an automobile, and is used for transmitting the movement of a handle shaft to a steering gear. 2. Description of the Related Art A cross joint called a cardan joint has been widely known as a universal joint used for a steering device of an automobile. For example, Japanese Utility Model Application No. 5-3652
Japanese Unexamined Patent Publication (Kokai) No. H11-15087 discloses a universal joint as shown in FIG. 11 which is incorporated in a steering device as shown in FIG. As shown in FIG. 10, the steering device is configured to transmit the movement of the steering wheel 1 to a steering gear 4 via a steering shaft 2 and an intermediate shaft 3, and to steer the wheels by the steering gear 4. The steering shaft 2 and the steering gear 4
The input shaft 5 is usually not provided on the same straight line as the input shaft 5. For this purpose, an intermediate shaft 3 is provided between the two shafts 2 and 5, and both ends of the intermediate shaft 3 and the ends of the steering shaft 2 and the input shaft 5 are connected to the universal joints 6 and 6 to which the present invention is applied. Are coupled through. [0003] Regarding the structure of each of these universal joints 6, 6,
This will be described with reference to FIG. 11 and FIG. The structure shown in FIG. 11 is a so-called anti-vibration joint for preventing transmission of vibration, but the universal joint to which the present invention is applied does not necessarily have to have the anti-vibration structure. Therefore, in the following description, the vibration proof structure is omitted, and the universal joint 6 will be described. The universal joint 6 is composed of a pair of yokes 7a and 7b, each of which is bifurcated from a metal material having sufficient rigidity, and a cross shaft 8 made of a hard metal such as an alloy steel. . At both ends of the yokes 7a, 7b, circular holes 9, 9 concentric with each other are formed. And each circular hole 9, 9
In addition, bearing cups 10, 10 also made of a hard metal such as bearing steel or the like and having a bottomed cylindrical shape are internally fitted and fixed with their openings facing each other. The cross shaft 8 has a shape such that the middle portions of a pair of pillars are orthogonal to each other,
It has four shaft portions 11, 11 each having a columnar shape. The four shaft portions 11, 11 are inserted into the bearing cups 10, 10, respectively. A radial bearing 12, such as a needle bearing, is provided between the inner peripheral surface of each of the bearing cups 10, 10 and the outer peripheral surface of each of the shaft portions 11, 11.
12 and the yokes 7a with respect to the cross shaft 8;
7b is made to oscillate with a light force. With this configuration, even when the center axes of the yokes 7a and 7b do not coincide with each other, the transmission of the rotational force between the yokes 7a and 7b can be performed with almost no transmission loss. The basic structure of the universal joint 6 is as described above. In such a universal joint 6, between the base 13 of the cross shaft 8 and the openings of the bearing cups 10, 10. , Are provided with seal rings 14, 14, respectively. These seal rings 14 prevent the muddy water and the like from entering the installation portions of the radial bearings 12, 12, thereby ensuring the durability of the universal joint 6.
Further, bottomed insertion holes 15, 15 are respectively formed in the center portions of the four shaft portions 11, 11, and the shafts of the shaft portions 11, 11 are opened in the end surfaces of the shaft portions 11, 11, respectively. It is formed over the direction. And each of these insertion holes 15,
As shown in detail in, for example, Japanese Utility Model Publication No. 64-2982, pins 16
6 is inserted. Conventionally, each of these pins 16 has been formed in a shape as shown in FIG. 13 or FIG. That is, the flange-shaped large-diameter portion 1 is provided at both axial ends of the cylindrical small-diameter portion 17.
8 and 18 are formed, and the outer end surfaces of the large diameter portions 18 and 18 are formed as protruding surfaces 19 and 19 having a truncated cone shape. In the example shown in FIG. 13, ribs 20, 20 are formed from both ends in the axial direction of the small-diameter portion 17 to the base ends of the large-diameter portions 18, 18, and the example shown in FIG. Such ribs 20, 2
0 is omitted. In any case, when assembling the universal joint 6, these pins 16, 16 are inserted into the respective insertion holes 1.
5, 15 and one end is inserted into each of these insertion holes 15, 1
5 and the other end of each bearing cup 1
It hits the bottom of 0,10. The pins 16, 16 are stretched between the bearing cups 10, 10 and the shafts 11, 11 so that the open ends of the bearing cups 10, 10 and the base 13 are extended. Prevents the distance from being too short.
This is to prevent the sealings 14 and 14 from being excessively compressed and, conversely, the compression amount from being excessively reduced. That is, a thrust load is applied between the cross shaft 8 and the bearing cups 10 and 10 when the universal joint 6 is used. Therefore, if no countermeasure is taken, the seal ring 14 on the thrust load acting side (anchor side) is excessively compressed and the durability is impaired, and the compression amount of the opposite side (anti-anchor side) seal ring 14 decreases. Too much, this seal ring 14
This is because the sealing performance is impaired. Each of the above pins 1
The bearings 6 and 16 have a role of supporting the thrust load in such a manner as to maintain the compression amount of each of the seal rings 14 and 14 within an appropriate range. The above-mentioned pins 16 and 1 which fulfill such a function
In order to perform the mounting work of No. 6, first, each of these pins 16,
16 is inserted into each of the insertion holes 15,
Insert at 15. At this time, when the pins 16 shown in FIG. 13 are used, the pins 16 are inserted into the insertion holes 1 while plastically deforming the outer peripheral edges of the ribs 20.
5 and 15 are press-fitted to the deep ends of the respective insertion holes 15 and 15. After the press-fitting, these pins 16 and 16 do not drop out of the insertion holes 15 and 15 carelessly. Rib 20,
When using the pin 16 shown in FIG. 14 which does not have the pin 20, the pins 16 are inserted into the insertion holes 15 before the bearing cups 10 are mounted as described below. During this time, these pins 16 are held down in order to prevent the pins 16 from falling off. In this manner, with the pins 16, 16 inserted into the insertion holes 15, 15, the shafts 11, 11 are inserted.
Are positioned in the circular holes 9 of the yoke 7a (7b). Then, the bearing cups 10 and 10 are press-fitted into the circular holes 9 and 9 from the outer end opening side, and the bearing cups 10 and 10 are directed toward the shafts 11 and 11 in a direction approaching each other. Press. Of course, prior to the pressing operation, the seal rings 14 are fitted to the base ends of the shafts 11. During the pressing operation, the radial bearings 12, 12 are set inside the bearing cups 10, 10, respectively. Further, the open ends of the bearing cups 10 and 10 are previously squeezed inward in the diametrical direction. By the pressing operation, the bearing cups 10, 10 on the opposite side in the axial direction are fixedly fitted in predetermined positions in the respective circular holes 9, 9, and at the same time, the pins 16, 16 are compressed in the axial direction. Is done. That is, the small diameter portion 1 of each of the pins 16
By being strongly clamped between the bottom surfaces of the bearing cups 10, 10 and the inner surfaces of the insertion holes 15, 15, the members 7, 17 are deformed into a beer barrel shape as shown in FIG. In this state, the pins 16 are connected to the bearing cups 10 and 10, respectively.
Between the bottom surface of the bearing cup and the inner surface of each of the insertion holes 15, 15, regardless of the thrust load.
0 and 10 are prevented from being displaced in the axial direction. As a result,
The compression amount of each of the seal rings 14, 14 is appropriately maintained. Since the contact area between the bottom surfaces of the bearing cups 10, 10 and the protruding surfaces 19, 19 is small, the friction loss at the contact portions between these bottom surfaces and the protruding surfaces 19, 19 can be small. Conventionally, a polyacetal resin has been used as a synthetic resin for forming the pins 16. When a compressive load is applied to the polyacetal resin pins 16, 16, the relationship between the compressive load and the amount of compression is as follows:
As shown by the dashed line a in FIG. 15, it becomes smooth. In other words, a slight difference in the compression load does not greatly affect the compression amount. Therefore, the pressing operation does not cause a large difference in the amount of compression between the pair of pins 16, 16 located at positions opposite to each other in the axial direction. That is, these pins 16, 16
May vary slightly due to errors (dimensional errors, material quality errors) that cannot be avoided in manufacturing. If the relationship between the compression load and the amount of compression is smooth as shown by the dashed line a, there is no large difference in the amount of compression between the pair of pins 16 and 16 and the 1 There is no large difference in the amount of compression between the pair of seal rings 14, 14. [0011] However, in the case of a conventional universal joint constructed and operated as described above, the pin 1
Due to the material of the synthetic resin that constitutes 6 and 16, there are the following problems to be solved. That is, these pins 16,
The polyacetal resin conventionally used as the synthetic resin constituting the 16 does not always have sufficient heat resistance, whereas the universal joint 6 constituting the steering device is provided in a high-temperature engine room. In particular, the temperature in the engine room tends to increase due to a recent increase in engine output and a decrease in space in the engine room due to an increase in accessories. Moreover, since the universal joint for the steering device is often arranged adjacent to the exhaust pipe, it must be considered that the universal joint is exposed to a considerably high temperature. In the case of the pins 16 made of polyacetal resin, they are softened and deformed when exposed to a high temperature, and as a result, each pin 16
There is a possibility that a gap may be formed between the end of the bearing cup and the bottom surface of the bearing cup 10, 10. If a gap occurs, rattling occurs at the universal joint 6 and undesired phenomena such as discomfort to the driver operating the steering wheel 1 (FIG. 10) occur. The above-mentioned problem can be solved by using a polyphenylene sulfide-based resin (hereinafter referred to as "PPS") having excellent heat resistance as the synthetic resin constituting the pins 16, 16. , Instead, PPS
Due to the characteristics described above, the following problem occurs. That is, when a compressive load is applied to a PPS pin,
The relationship between the compression load and the compression amount is as shown by a broken line b in FIG. As is clear from the broken line b, a yield point clearly appears as a material characteristic of PPS. As a result, when the compression load and the compression amount exceed certain values, the compression amount suddenly increases (increases) despite the small (small) change amount of the compression load. There is no particular problem if the above-mentioned yield point is located outside the range of use. However, if the pins 16, 16 incorporated in the universal joint 6 generally used for a steering device or the like are made of PPS, this yield A dot appears within the range of use. When the yield point appears in the range of use as described above, the compression amount of one pin 16 of the pair of pins 16 provided on the opposite side in the axial direction is reduced to the compression amount of the other pin 16. In comparison, they are significantly different. That is, the bearing cups 10 and 10 are inserted into the circular holes 9 and
9 (for example, FIG. 12).
Before the small diameter portion 17 of the pin 16 (above) reaches the yield point, the small diameter portion 1 of the other pin 16 (for example, the lower portion of FIG. 12).
7 may reach the yield point. In such a case, with the pushing operation which continues even after the small diameter portion 17 of the other pin 16 reaches the yield point, the compression amount of the other pin 16 is reduced as compared with the compression amount of the one pin 16. The amount increases.
It is sufficient that the yield points of the small diameter portions 17 and 17 of the pair of pins 16 and 16 are as close as possible.
As shown in FIG. 12, the amount of compression of the pair of pins 16, 16 greatly differs. As a result, the amount of compression of the seal ring 14 corresponding to the other pin 16 is large (excessive), and the seal ring 14 corresponding to the one pin 16 is compressed.
Compression amount becomes insufficient (insufficient). The variation in the amount of compression of the seal rings 14, 14 due to the bias of the amount of compression of the pins 16, 16 is as follows.
Insufficient durability of the seal ring 14 (when the compression amount is excessive) or deterioration of the sealing performance (when the compression amount is insufficient)
Invite. For this reason, conventionally, all the compression amounts of the seal rings 14, 14 of the universal joint 6 in which the mounting of the bearing cups 10, 10 is completed are inspected, and defective products are discarded. Because of this,
The production cost of the universal joint 6 has been increased due to the reduced yield. Regardless of the variation in the compression characteristics of the pins 16, 16, the pins 16, 16 provided on the opposite side in the axial direction are provided.
In order to prevent the amount of compression from varying, it is conceivable to press the bearing cups 10 and 10 while the cross shaft 8 is fixed. That is, 4 forming the cross shaft 8
Of the shafts 11, 11, two of which are not pressed (for example, arranged horizontally in FIG. 12)
The above-mentioned pushing work is performed while supporting and fixing 1, 11. If the pushing operation is performed in this manner, the above-mentioned variation in the amount of compression can be prevented, but the operation of fixing the cross shaft 8 is required, and the manufacturing process of the universal joint 6 is complicated, and the manufacturing cost of the universal joint 6 is also increased. Will be higher. The universal joint of the present invention was invented in view of such circumstances. A universal joint according to the present invention has a pair of yokes each having a bifurcated shape, and two ends each of which are formed like a conventional universal joint. A circular hole formed concentrically with each other, a cylindrical bearing cup with a bottom, which is internally fitted and fixed inside each of the circular holes with the openings facing each other, and each of which has a cylindrical shape. Radial bearings having a plurality of shaft portions, a cross shaft in which each shaft portion is inserted into each of the bearing cups, and a radial bearing provided between an inner peripheral surface of each of the bearing cups and an outer peripheral surface of each of the shaft portions. A seal ring provided between a base of the cross shaft and an opening of each of the bearing cups; and an inner side of the cross shaft with an opening at an end face of each of the shaft portions. A formed bottomed insertion hole,
A pin made of synthetic resin is inserted into each insertion hole, one end of which is abutted against the back end of the insertion hole, and the other end is abutted against the bottom surface of each bearing cup. In particular, in the universal joint of the present invention, the synthetic resin forming each of these pins is PPS. Each of the pins is formed at both ends in the axial direction, and is provided with a large cross-sectional area that can be inserted into each of the insertion holes, and is provided in series between the two large cross-sectional areas in the axial direction. A small cross-sectional area and an interrupted area. The universal joint of the present invention configured as described above functions to transmit a rotational force between a pair of shafts that do not exist on the same straight line, and that each pin is located at the back end of the insertion hole. The effect of restricting the amount of compression of the seal ring to an appropriate range by stretching between the bearing and the inner surface of the bearing cup is the same as that of the above-mentioned conventional universal joint. In particular, in the case of the universal joint of the present invention, the relationship between the compression load and the compression amount of each pin can be made smooth.
That is, when a compressive load is applied to each of these pins, the small cross-sectional area is deformed first, and then the interrupted area is deformed. At the point when the break area begins to deform, both of the pair of pins have been somewhat compressed. Before the deformation of the interrupted area starts, it passes through the yield point of the PPS at the small cross-sectional area that is easily deformed, but after the small cross-sectional area is sufficiently compressed, the interrupted area of the pair of pins is used. Starts to be compressed by further applying a compressive load. In other words, after the yield of the small cross section,
Yielding of the interrupted area occurs successively. As a result, the apparent characteristics of the pin as a whole become smooth such that there is no yield point, and a large difference does not occur in the compression amount of the interrupted area of the pair of pins. As a result, in spite of using PPS having excellent heat resistance, as in the case of using polyacetal resin, the amount of compression of a pair of seal rings existing at positions opposite to each other in the axial direction can be reduced. It can be placed within the appropriate range. 1 to 4 show a first embodiment of the present invention. The feature of the present invention is that the pins 16a, 16a are P
The shape of each of the pins 16a, 16a has been devised so as to use a PS and to keep the amount of compression of the pair of seal rings 14, 14 provided at positions opposite to the cross shaft 8 in the axial direction within an appropriate range. is there. Since the structure and operation of the other parts are the same as those of the conventional structure described above, the same parts are denoted by the same reference numerals, and duplicated description is omitted or simplified.
The following description focuses on the features of the present invention. Although the universal joint 6 shown in FIG. 1 does not have a vibration-proof structure, it is free to have a vibration-proof structure as shown in FIG. At both ends in the axial direction (vertical direction in FIGS. 1 to 3) of the pins 16a, 16a made of PPS, cylindrical large cross-sectional areas 21, 21 are formed. This large cross section 21, 2
The outer diameter of 1 is formed by four shaft portions 11, 11 constituting the cross shaft 8.
Are equal to or slightly smaller than the inner diameters of the insertion holes 15 and 15 opened at the center of the end face. Therefore, each of these large cross-sectional area portions 21 is provided with the above-described insertion hole 15.
It can be inserted freely. Further, a small cross-sectional area portion 22 having a columnar shape is also formed at the center in the axial direction of each of the pins 16a, 16a. Further, between the both ends in the axial direction of the small cross-sectional area 22 and the large cross-sectional areas 21, interrupted area sections 23 are provided, respectively. Each of the above pins 16a having such a shape,
16a is inserted into the insertion holes 15, 15 formed in the shaft portions 11, 11, respectively, and is stretched between the inner ends of the insertion holes 15, 15 and the bottom surfaces of the bearing cups 10, 10. In the case of the illustrated embodiment, each of the above-mentioned interrupted area portions 2
Ribs 20, 20 are formed from 3, 23 to the large cross-sectional area portions 21, 21, respectively. Therefore, each of the insertion holes 1
The pins 16a, 16a inserted in the bearings 5, 15 do not accidentally fall off before the bearing cups 10, 10 are mounted. In the case of the universal joint of the present invention including the pins 16a and 16 as described above,
a, the relationship between the compressive load and the amount of compression can be made smooth, and a pair of pins 16a, 16
The compression amount of “a” can be made substantially uniform. That is, each of the bearing cups 10 is inserted into a pair of circular holes 9 formed in the yoke 7a.
10, the pins 16a, 16a
When a compressive load is applied to a, the small sectional area portion 22 is first compressed and deformed. Then, in a state where the small cross-sectional area portion 22 has been completely compressed and deformed to a certain extent, each of the interruption area portions 23 and 23 starts to be compressed and deformed. Note that while the small cross-sectional area 22 is being compressed and deformed, the interruption area parts 23 and 23 are also slightly compressed and deformed, but are much smaller than the deformation of the small cross-sectional area 22. Therefore, at the time when each of the interruption area portions 23, 23 starts to substantially compressively deform, the pair of pins 16
Both a and 16a are compressed to some extent by the compression deformation of the small cross-sectional area 22. Before the deformation of the interrupted area portions 23 starts, the small cross-sectional area portion 22 passes through the yield point of PPS. Incidentally, at the stage where the compression deformation of each of the interruption area portions 23, 23 is started,
The compression amount of each of the pins 16a, 16a as a whole has not yet reached the use range. In other words, each of the interruption area portions 23, 2
At the point when 3 starts substantially compressive deformation, the small cross-sectional area 22 is almost completely compressed and deformed. Therefore, even if there is a difference between the yield points of the small cross-sectional area portions 22 of the pair of pins 16a, 16a, when the pressing of the pair of bearing cups 10, 10 is completed, the difference is determined by the compression of the entire pins 16a, 16a. Has little effect on volume. After the small cross-sectional area portion 22 is compressed and cut, each of the interrupted area portions 2 of the pair of pins 16a, 16a
The members 3 and 23 start to be compressed substantially when a further compressive load is applied as the pair of bearing cups 10 and 10 continue to be pushed. The pair of pins 16
The a and 16a are each compressed by a predetermined amount as a whole by compressing the respective interrupted area portions 23 and 23 in addition to the respective small cross-sectional area portions 22. That is, each of these pins 16
a and 16a represent the amount of compression in the small cross-sectional area portion 22;
As a result of the addition of the compression amount in each of the interruption area portions 23, 23, compression is performed as a whole. Since the amount of compression in the small cross-sectional area 22 occupies a certain amount of the total amount of compression for each of the pins 16a, 16a, the compression of the interrupted area portions 23, 23 The amount will be limited. Therefore, the compression of each of the interruption area portions 23, 23 does not pass the yield point, or even if it does, it only passes immediately before the completion of the pushing operation of the pair of bearing cups 10, 10. Therefore, there is no large difference in the amount of compression between the interruption area portions 23 of the pair of pins 16a. Thus, these 1
The pair of pins 16a, 16a further compresses the interrupted area portions 23, 23 in a state where the amount of compression by the small cross-sectional area portion 22 is secured, and the apparent compression characteristics of these pins 16a, 16a are as shown in FIG. As shown by a solid line c in FIG. Therefore, in spite of using PPS having excellent heat resistance, similarly to the case of using polyacetal resin, a pair of pins 16 located at positions opposite to each other in the axial direction is used.
It is possible to prevent a large difference between the compression amounts of a and 16a.
As a result, the amount of compression of the pair of seal rings 14, 14 also provided at positions opposite to each other in the axial direction can be kept within an appropriate range. For this reason, there is no possibility that any of the seal rings 14 is excessively compressed and the durability is reduced, or the sealing performance is not impaired due to insufficient compression of the seal ring 14 on the opposite side. Experiments conducted by the present inventors have confirmed that the dimensions of the PPS pin 16a should be regulated as follows in order to make the apparent compression characteristics of the pin 16a smooth. Was done. First, when a large cross sectional area portion 21, 21 between the spacing D ₂₁ formed at both axial ends and 1.0, the length L ₂₂ of the small cross-sectional area portion 22 of 0.25 to 0.4 range paid to the _{(L 22 = (0.25~0.4) D} 21). The absolute value of the length L ₂₂ is smaller than the compression amount L ₀ required as a whole pin 16a. In short, even if the small cross-sectional area portion 22 is completely compressed (a very large load is required for further compression), the compression amount is equal to the required compression amount L ₀ . so as not to reach, to regulate the length dimension L _22. Further, the length dimensions of the interruption area portions 23, 23 present on both sides in the axial direction of the small sectional area portion 22 are made equal to each other.
Further, the cross-sectional area S23 of each of the interruption area portions ₂₃ , _{23 is set} to 1
, The sectional area S ₂₂ of the small sectional area portion 22 is set to 0.
Pay in the range of 5~0.7 (S ₂₂ = (0.5~0.7)
S _23). Next, FIGS. 5 to 7 show a second embodiment of the present invention. In the case of this embodiment, the pin 16b made of PPS is used.
Reinforcing ribs 24, 24 each extending in the axial direction are formed at four positions on the outer peripheral surface of the small cross-sectional area portion 22. In the case of the present embodiment, the small cross-sectional area 22 is less likely to be bent when the pin 16b is pressed into the insertion hole 15 due to the presence of the reinforcing ribs 24, 24. In the case of this embodiment, it is assumed that the cross-sectional area of the small cross-sectional area 22 includes these reinforcing ribs 24, 24. That is, the cross-sectional area regulation of the formula _{(S 22 = (0.5~0.7) S} 23) , the reinforcing ribs 2
It is necessary to fill with a cross-sectional area including the cross-sectional areas of 4, 24.
The number of the reinforcing ribs 24 is not particularly limited in terms of the function of the pin 16b. However, the reinforcing ribs 24, 2
If the number of 4 is 2 or 4 and they are arranged at regular intervals in the circumferential direction, there is no undercut portion at the time of injection molding, and it is advantageous since molding can be performed with a simple split mold. Other configurations and operations are the same as those of the above-described first embodiment. Next, FIGS. 8 and 9 show a third embodiment of the present invention. In the case of this embodiment, the pin 16c made of PPS is used.
The cross-sectional shape of the small cross-sectional area 22 is square. Other configurations and operations are the same as those of the above-described first embodiment. In each of the illustrated embodiments, the small cross-sectional area 22 is sandwiched from both sides in the axial direction by the pair of interruption area parts 23, 23. However, in order to obtain the operation and effect of the present invention, this is not necessarily the case. The arrangement need not be such. The point is that at least one small cross-sectional area 22 and at least one interruption area 23 may be provided in series in the axial direction between the large cross-sectional areas 21 at both ends. However, when the arrangement is as shown in the illustrated embodiment, there is an effect that the step between the cross-sectional areas adjacent to each other in the axial direction is reduced, and the deformation accompanying the molding can be reduced. Since the universal joint of the present invention is constructed and operates as described above, the following effects can be obtained at the same time. Since sufficient heat resistance can be ensured by using a PPS pin, problems such as rattling hardly occur even when used for a long time in a high temperature environment such as in an engine room. Since the amount of compression of the seal ring can be properly adjusted, the durability and sealing performance of the seal ring can be ensured. Since no troublesome work such as fixing the cross shaft is required at the time of assembling, the yield can be improved and the cost can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cut-away side view showing a first embodiment of the present invention. FIG. 2 is a view corresponding to an AA cross section of FIG. 1, showing a state where only one yoke is mounted on a cross shaft. FIG. 3 is an enlarged side view of a pin used in the first embodiment. FIG. 4 is a sectional view taken along line BB of FIG. 3; FIG. 5 is a partially enlarged cross-sectional view showing the second embodiment of the present invention in a state where the bearing cup is being pushed. FIG. 6 is a side view of a pin used in the second embodiment. FIG. 7 is a cross-sectional view taken along the line CC of FIG. FIG. 8 is a side view of a pin showing a third embodiment of the present invention. FIG. 9 is a cross-sectional view taken along the line DD of FIG. FIG. 10 is a perspective view of a steering device incorporating a universal joint. FIG. 11 is a partially cut-away side view showing an example of a conventionally known universal joint. FIG. 12 is a view similar to FIG. 2, showing a conventional universal joint. FIG. 13 is a side view showing a first example of a conventionally used pin. FIG. 14 is a side view showing the second example. FIG. 15 is a diagram showing a relationship between a compressive load applied in the axial direction of the pin and an amount of compression in the axial direction of the pin. DESCRIPTION OF THE SYMBOLS 1 Steering wheel 2 Steering shaft 3 Intermediate shaft 4 Steering gear 5 Input shaft 6 Universal joints 7a, 7b Yoke 8 Cross shaft 9 Circular hole 10 Bearing cup 11 Shaft 12 Radial bearing 13 Base 14 Seal ring 15 Insertion hole 16, 16a, 16b, 16c Pin 17 Small diameter portion 18 Large diameter portion 19 Projecting surface 20 Rib 21 Large cross-sectional area 22 Small cross-sectional area 23 Interruption area 24 Reinforcing rib

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16D 3/26-3/41

Claims (1)

(57) [Claims 1] A pair of yokes each formed in a bifurcated shape, circular holes formed concentrically at both ends of each yoke, and mutual openings facing each other. A cylindrical bearing cup having a bottom and fixed to the inside of each of the circular holes in a state where the bearings are closed, and four shaft portions each formed in a cylindrical shape, and each shaft portion is connected to each of the bearings A cross shaft inserted into the cup, a radial bearing provided between an inner peripheral surface of each of the bearing cups and an outer peripheral surface of each of the shaft portions, a base of the cross shaft, and an opening of each of the bearing cups , A bottomed insertion hole formed along the axial direction inside the cross shaft in a state of being opened at the end face of each of the shaft portions, and inserted into each of the insertion holes. And one end of each is abutted against the back end of the insertion hole, and the other end is protruded to the bottom surface of each bearing cup. In the universal joint having a pin made of synthetic resin applied thereto, the synthetic resin constituting each of these pins is a polyphenylene sulfide-based resin, and each of the pins is formed at both ends in the axial direction. It has a large cross-sectional area that can be inserted into the insertion hole, and a small cross-sectional area and an interrupting area that are provided in series in the axial direction between the two large cross-sectional areas. And universal joint.