JP5974525B2 - Cross shaft type universal joint - Google Patents

Description

  The present invention has a shell-type outer ring formed by bending a metal plate into a bottomed cylindrical shape, and a gap between the opening end of the outer ring and the outer peripheral surface of a shaft inserted on the inner diameter side of the outer ring The present invention relates to an improvement of a cross shaft type universal joint incorporating a shell type needle bearing that is used in a state in which is sealed with a seal ring.

[Description of prior art]
For example, a cross-shaft universal joint is incorporated at the joint between the end of the drive shaft that constitutes the drive system of an automobile and another rotary shaft, and the drive shaft and the rotary shaft are arranged non-linearly. The rotational force can be transmitted freely. Alternatively, a cross shaft type universal joint is incorporated between the steering shaft and the intermediate shaft constituting the automobile steering device, between the intermediate shaft and the pinion shaft of the steering gear unit, and arranged on a non-linear line. Rotational force can be transmitted between these shafts. The structure of the cross shaft type universal joint used in such a part has been widely known as described in, for example, Patent Documents 1 to 7.

  FIG. 7 shows an example of a cruciform universal joint that has been widely known. The universal joint 1 is formed by coupling a pair of yokes 2a and 2b and a cross shaft 3 via four shell needle bearings 4 and 4 so as to be relatively displaceable. Each of the yokes 2a and 2b has a bifurcated shape with a pair of arm portions 5a and 5b, and circular holes 6a and 6b are formed at the tips of the arm portions 5a and 5b, respectively. Yes. The circular holes 6a, 6a (6b) formed at the tip of the same yoke 2a (2b) are concentric with each other. The cross shaft 3 is formed by fixing four shaft portions 8 and 8 radially (at equal intervals in the circumferential direction) to the outer peripheral surface of the coupling base portion 7. The yokes 2a and 2b constituting the universal joint 1 support the shafts 8 and 8 in the circular holes 6a and 6b so as to be swingably displaceable by the shell type needle bearings 4 and 4, respectively. Thus, the oscillating displacement and the torque transmission are freely coupled via the cross shaft 3.

  Each of the shell type needle bearings 4, 4 includes a single shell type outer ring 9 and a plurality of needles 10, 10. The shell type outer ring 9 is formed by bending a hard metal plate such as a carbon steel plate or a case-hardened steel plate by plastic working such as deep drawing, and includes a cylindrical portion 11, a bottom plate portion 12, Unit 13. Of these, the bottom plate portion 12 closes the entire axial end of the cylindrical portion 11 (on the outer surface side of the arm portions 5a and 5b in the assembled state in the circular holes 6a and 6b). The inward flange 13 is radially inward from the other axial end of the cylindrical portion 11 (the inner side of the arms 5a and 5b in the assembled state in the circular holes 6a and 6b). The surface facing the needles 10 and 10 is curved in a direction that becomes a concave surface.

  Each of the shell type needle bearings 4, 4, each having the above-described configuration, has the shell type outer rings 9, 9 fitted into the circular holes 6 a, 6 b by internal fitting and fixed, and each needle 10 and 10 are assembled in a state where the shaft portions 8 and 8 of the cross shaft 3 are inserted. In this assembly operation, the shell type needle roller bearings 4 and 4 are inserted into the circular holes 6a and 6b in a state where the shafts 8 and 8 are inserted into the circular holes 6a and 6b. This is performed by press-fitting from the outer surface side openings of the arms 5a and 5b. In addition, seal rings 14 and 14 are preliminarily fitted and supported on the base end portions of the shaft portions 8 and 8 by interference fitting. In the state after the assembly is completed, the inner peripheral surface of the cylindrical portion 11 of each shell type outer ring 9, 9 functions as an outer ring raceway, and the outer peripheral surface of each shaft portion 8, 8 functions as an inner ring raceway.

  Each of the seal rings 14, 14 is formed by reinforcing an elastic material 16 with a cored bar 15. Among these, the elastic member 16 includes a radial seal lip 17 and a thrust seal lip 18. In a state where the cross shaft 3 and each shell type outer ring 9, 9 are combined to form the universal joint 1, the distal end edge of the radial seal lip 17 is within the outer peripheral surface of each shell type outer ring 9, 9. It abuts elastically at the end near the opening over the entire circumference. Further, the leading edge of the thrust seal lip 18 is in elastic contact with the outer surfaces of the inward flange portions 13 and 13 over the entire circumference. In this state, the seal rings 14, 14 block the internal space and the external space of the shell type outer rings 9, 9, and lubricant such as grease sealed inside the shell type outer rings 9, 9. Is prevented from leaking to the outside, and foreign matter is prevented from entering the inside of each of the shell-type outer rings 9, 9 from the outside.

  When the universal joint 1 as described above is used in a state where it is assembled to, for example, a connecting portion between the end portion of the drive shaft and another rotating shaft, from the aspect of achieving both low cost and ensuring durability, There is room for improvement in this respect. First, in order to reduce the cost, carbon steel sheets (skin-hardened steel, bearing steel, etc.) that can keep procurement costs low as the metal plates constituting the shell-type outer rings 9, 9 incorporated in the shell-type needle bearings 4, 4 described above. Are preferably used). However, in the case of a carbon steel plate, it is inevitable that the surface is corroded if the use conditions become severe. For example, when the universal joint 1 is incorporated in a drive system of an automobile, a corrosive substance such as muddy water rolled up during running or water mixed with a snow melting agent adheres to the surface of the shell type outer rings 9 and 9. Then, rust is generated on this surface.

  The surface portions of the shell-type outer rings 9 and 9 where rust is generated have a large roughness (a rough surface having a large friction coefficient), and the tips of the seal lips 17 and 18 constituting the seal rings 14 and 14. These seal lips 17 and 18 wear out in strong friction with the edges. For example, as shown in FIG. 8A at the initial stage, the tip edges of the seal lips 17 and 18 are in contact with the surface of the shell-type outer ring 9 without any gaps over the entire circumference. Even if the rust 19 is generated on a part of the surface of the shell type outer ring 9 as shown in FIG. 5B, the leading edge of the radial seal lip 17 is first caused by friction with the rust 19. Parts wear out. As a result, a gap 20 is formed between the distal end edge of the radial seal lip 17 and the surface of the shell-type outer ring 9. As a result, the corrosive substance enters deeper than the radial seal lip 17 through the gap 20, and as shown in FIG. 19a occurs. Due to the friction with the rust 19a, the tip edge portion of the thrust seal lip 18 is worn, and a gap 20a is also formed between the tip edge of the thrust seal lip 18 and the surface of the shell type outer ring 9. As a result, the sealing function by the respective seal lips 17 and 18 is reduced or lost, and it becomes impossible to prevent the leakage of the lubricant and the invasion of foreign matter.

  As described in Patent Document 6, the surface of the universal joint after assembly may be coated for rust prevention including the surface of the shell type needle bearing. However, in this case, as described in the above-mentioned Patent Document 6, not only there is a concern that the sealing performance is deteriorated due to the presence of the stepped surface of the coating film, but the relative displacement between the seal ring and the shell type outer ring is caused. Thus, the corrosive substance adheres to the surface of the shell-type outer ring that is not covered with the coating film, and the possibility that the corrosion proceeds from this portion remains. If the entire outer surface of the shell type outer ring is painted prior to assembly to the yoke, the above-mentioned problems can be solved, but the outer diameter of the shell type outer ring is increased by the amount of the coating film. This not only hinders the work of press-fitting into the circular hole on the yoke side, but also deteriorates the dimensional accuracy after press-fitting.

  If the shell type outer ring 9 is made of a stainless steel plate, it is possible to suppress the generation of the rusts 19 and 19a as described above and to ensure the durability of the universal joint 1 incorporating the shell type needle bearings 4 and 4. However, a stainless steel plate is not only more expensive than a carbon steel plate, but it is also troublesome to draw a material having the required hardness, which makes the processing itself difficult and increases the processing cost. For this reason, it is desirable to avoid the use of stainless steel sheets in view of cost reduction.

  Patent Documents 8 and 9 describe the prevention of an insoluble metal phosphate-treated film (in the case of Patent Document 8), a phosphate-treated film (in the case of Patent Document 9), etc. on the surface of a rolling bearing component such as an outer ring. The formation of a chemical conversion coating for rust is described. These chemical conversion treatment coatings do not require the outer diameter of the outer ring to be substantially increased, and a certain degree of antirust effect can be expected. And, for example, it is possible to prevent the formation of through holes in the shell-type outer ring or the occurrence of corrosion that causes a significant decrease in strength during the period of use required for the universal joint. However, when the use conditions become severe, there is a possibility that thin rust will be generated on the surface. The wear of the tip edge of the seal lip as described above proceeds even by such thin rust. For this reason, even if the usage conditions are severe, it is not always sufficient to maintain the sealing performance of the seal ring for a long period of time and to ensure the durability of the universal joint incorporating the shell type needle bearing. .

[Explanation of undisclosed invention]
In view of the circumstances as described above, the present inventors previously invented an invention that makes it possible to realize a structure of a cross shaft universal joint capable of achieving both low cost and ensuring durability (Japanese Patent Application No. 2011-013845). In the invention of the cruciform universal joint according to the present invention, the entire outer surface of the shell type outer ring incorporated in the cruciform universal joint has a certain degree of corrosion resistance, and the shell type outer ring and the coating film described below It is covered with a chemical conversion treatment film that improves the bond strength. And, in the outer surface of the shell-type outer ring, the chemical conversion coating is exposed to a portion that is fitted in a circular hole formed in the outer member in use and is in contact with the inner peripheral surface of the circular hole, At least a part of the part removed from the circular hole is covered with a coating film for improving corrosion resistance.

  In the case of the cruciform universal joint of such a prior invention, only the chemical conversion coating exists in the portion of the outer peripheral surface of the shell-type outer ring that is fitted into the circular hole of the outer member by an interference fit, Even if a coating film is present, the amount is small. The chemical conversion coating film is extremely thin and hardly increases the outer diameter of the shell-type outer ring. For this reason, this shell-type outer ring can be fitted and fixed to the circular hole without interference, and part of the coating can be scraped off due to internal fitting work, There is almost no. In addition to the chemical conversion coating, the parts that require a high degree of corrosion resistance, such as the part where the tip edge of the seal lip slides, are covered with the coating film as well. Can be prevented. Therefore, it is possible to prevent the tip edge of the seal lip from being worn due to friction with the surface of the shell type outer ring, which has become rough due to rust (corrosion product).

9 to 11 show three examples of the specific structure of the prior invention as described above.
First, the first example of the specific structure of the prior invention shown in FIG. 9 is the outer surface of the shell-type outer ring 9, that is, the outer surface (side surfaces opposite to each other) of the bottom plate portion 12 and the inward flange portion 13, and the cylindrical portion 11. Is entirely covered with an iron phosphate coating, which is a chemical conversion coating having corrosion resistance. The method for forming the iron phosphate coating is not particularly limited, and a general treatment method such as spraying a commercially available iron phosphate base treatment agent or immersing in this ground treatment agent can be used. There is. If such a base treatment is applied to the outer surface of the shell type outer ring 9, the outer surface of the shell type outer ring 9 can be degreased and a chemical conversion treatment film (iron phosphate film) can be formed on the outer surface. In addition, as a surface treating agent for forming this chemical conversion coating, in addition to the above iron phosphate type, various known antirust chemicals and coating base chemicals (for example, those for forming a zinc phosphate coating) Can also be used. Moreover, you may degrease using a known degreasing agent before chemical conversion treatment. Moreover, depending on use conditions, formation of the said chemical conversion treatment film can also be abbreviate | omitted. However, it is preferable that at least a part of the outer surface of the shell-type outer ring 9 excluding a part of the outer peripheral surface of the cylindrical portion 11 that contacts the inner peripheral surface of the circular hole 6a (6b) on the arm portion 5a (5b) side. The chemical conversion treatment film is present. More preferably, this chemical conversion coating is formed on the entire surface of the shell type outer ring 9. This also applies to the present invention described later.

  Further, a portion of the outer surface of the shell type outer ring 9 indicated by a broken line α in FIG. That is, among the outer peripheral surfaces of the cylindrical portion 11 constituting the shell type outer ring 9, the opening-side end portion (the end portion on the opposite side to the bottom plate portion 12) and the outer side surface of the inward flange portion 13 provided at the opening peripheral edge portion. In addition, the coating film 21 is formed. The coating material constituting the coating film 21 has good adhesion to the steel plate constituting the shell-type outer ring 9, is easy to form a coating film, has sufficient corrosion resistance, and The surface is not particularly limited as long as the surface can be made smooth, and for example, an epoxy resin-based paint can be preferably used.

  The coating film 21 is formed in the radial and thrust seal lips 17 and 18 constituting the seal ring 14 based on the torque applied between the yoke 2a (2b) and the cross shaft 3 when the universal joint is used. The part where the tip edge of the slidable part may come into sliding contact is completely included, and a part slightly wider than this part. That is, when the torque increases, the amount of elastic deformation of the yoke 2a (2b), the cross shaft 3, etc. increases, and the leading edges of the seal lips 17 and 18 deviate from the positions shown in FIG. However, the width of the coating film 21 is sufficiently wide so that the respective leading edges do not come off the coating film 21. Specifically, the inner diameter side end of the coating film 21 on the other end side in the axial direction is present at a position reaching the inner peripheral edge of the inward flange 13. Further, the outer end of the coating film 21 in the axial direction is located at a position where it slightly enters (for example, 0.5 mm to 1 mm) inside the circular hole 6a (6b). That is, the amount of protrusion of the shell-type outer ring 9 from the inner surface of the arm portion 5a (5b) of the yoke 2a (2b) excluding the tip is H, and the end surface (inward flange portion 13) of the shell-type outer ring 9 is defined. W−H = 0.5 mm to 1 mm, where W is the distance from the outer surface of the coating film 21 to the outer end of the coating film 21 in the axial direction (the axial width of the coating film 21). In addition, in order to form the coating film 21 only in the above-mentioned range, in addition to masking the axially intermediate portion of the bottom plate portion 12 to the cylindrical portion 11 with a cover or tape, A spraying operation for forming the coating film 21 is performed in a state of being covered with a cap.

  According to the first example of the specific structure of the prior invention configured as described above, it is possible to achieve both low cost and ensure durability of the cross shaft type universal joint incorporating the shell type needle bearing 4. That is, most of the outer peripheral surface of the cylindrical portion 11 constituting the shell type outer ring 9 is fitted into the circular hole 6a (6b) of the yoke 2a (2b) by an interference fit. Only the coating is present. The film of the chemical conversion coating is extremely thin, and the outer diameter of the shell type outer ring 9 is hardly increased. A part of the coating film 21 (a part in the circumferential direction of a part having a width of 0.5 mm to 1 mm) is fitted in the circular hole 6a (6b), but the part is suppressed slightly. It is done. Even in this portion, the cylindrical portion 11 is merely pushed into the circular hole 6a (6b) at the final stage of the work of fitting the cylindrical portion 11 into the circular hole 6a (6b). Moreover, in the case of this example, the thickness of the coating film 21 is suppressed to about 0.005 mm to 0.015 mm, although it is larger than the thickness of the chemical conversion treatment film. For this reason, the presence of the coating film 21 hardly hinders the work of fitting inside, and the coating film 21 is hardly scraped off during the fitting work.

  When the assembly of the cross shaft universal joint is completed, the leading edge of each of the radial and thrust seal lips 17 and 18 constituting the seal ring 14 is the surface of the coating film 21, and the width of the coating film 21. The slidable contact is sufficiently made from the both end edges in the direction toward the center side of the coating film 21. The surface of the coating film 21 is a smooth surface and has sufficiently excellent corrosion resistance. For this reason, even when used over a long period of time in a harsh corrosive environment, the surface of the portion where the tip edges of the seal lips 17 and 18 are in sliding contact does not become rough. That is, unlike the above-described conventional structure, the tip edge of the seal lip does not wear due to friction with the surface of the shell-type outer ring roughened by rust (corrosion product).

  Next, in the second example of the specific structure of the prior invention shown in FIG. 10, the coating film 21 a is applied to the outer surface of the bottom plate portion 12 indicated by the broken line β in FIG. 10 among the outer surfaces of the shell type outer ring 9. Forming. Since the bottom plate portion 12 exists inside the circular hole 6a (6b) formed in the yoke 2a (2b) and is located in a slightly recessed portion from the outer surface of the yoke 2a (2b), the circular hole 6a (6b) ) And corrosive substances such as muddy water containing snow melting salt are likely to accumulate in the portion surrounded by the inner peripheral surface and the bottom plate portion 12, and the corrosive environment becomes very severe. In general, if a chemical conversion treatment film having corrosion resistance is formed on the outer surface of the shell-type outer ring 9, the bottom plate portion 12 is corroded to the extent that it leads to the generation of through holes and a decrease in strength. There is nothing. However, if the coating film 21a similar to the coating film 21 of the first example having the specific structure described above is formed on the bottom plate portion 12 as in the structure of this example, the durability of the bottom plate portion 12 is further enhanced. Can be improved.

  Furthermore, in the structure of the third example of the specific structure of the prior invention shown in FIG. 11, on the outer peripheral surface of the cylindrical portion 11 constituting the shell type outer ring 9, the end portion closer to the opening and the outer surface of the inward flange portion 13. The coating film 21 and the coating film 21a are formed on the outer surface of the bottom plate portion 12, respectively. For this reason, the operation and effect of the first and second examples of the specific structure described above can be obtained together.

  In the case of the structure according to the above-described prior invention, the seal ring 14 has only two seal lips, the radial seal lip 17 and the thrust seal lip 18. For this reason, when the use conditions are particularly severe, foreign matter such as dust passes through the sliding contact portion between the tip edges of the seal lips 17, 18 and the outer surface of the shell type outer ring 9. There is a possibility of getting inside. And if it enters, the durability of the cross shaft type universal joint incorporating the shell type needle bearing may be impaired.

  Patent Documents 6 and 7 describe the structure of a cross shaft type universal joint in which the seal structure by the seal ring is tripled by making the tip of the radial seal lip of the radial seal lip and the thrust seal lip into two branches. Has been. However, in the case of the conventional structures described in Patent Documents 6 and 7, rust preventive coating is not applied to the portion of the outer surface of the shell-type outer ring where the tip edge of each seal lip is in sliding contact. For this reason, the tip edge of the seal lip may be worn by the mechanism as shown in FIG.

Japanese Patent Application Laid-Open No. 8-135684 Japanese Patent Laid-Open No. 9-60650 JP 2005-48809 A JP 2006-29551 A JP 2009-127725 A JP 2010-1810115 A JP 2010-181016 A JP 2002-146837 A JP 2002-294465 A

  In view of the circumstances as described above, the present invention suppresses wear of the tip edge of the seal lip even under severe use conditions, and makes it difficult for foreign matter to enter the inside of the shell-type outer ring, resulting in more sufficient durability. The invention was invented to realize a structure of a cross-shaft type universal joint that is easy to ensure.

The cross shaft type universal joint of the present invention includes a pair of yokes, a total of four circular holes, a cross shaft, four shell needle bearings, and four seal rings.
Of these, the pair of yokes is formed in a bifurcated shape, each having a pair of arms.
Each of the circular holes is formed concentrically with each of the yokes at one end of each of the arm portions, which are both ends of the yokes.
Further, the cross shaft is formed by radially fixing four shaft portions on the outer peripheral surface of the coupling base portion, and is combined with both the yokes in a state where these shaft portions are inserted into the respective circular holes. .
Each of the shell type needle bearings is provided between an outer peripheral surface of each of the shaft portions and an inner peripheral surface of each of the circular holes, and each includes a shell type outer ring and a plurality of needles. . Of these, the shell-type outer ring is formed by bending a metal plate, and each arm portion among the cylindrical portion that is fitted and fixed inside each circular hole, and both axial ends of the cylindrical portion. A bottom plate portion that covers the entire one end side that is the outer surface side of each of the arm portions, and an inward flange portion that is bent radially inward from the other axial end side of the cylindrical portion that is the inner surface side of each arm portion. The needles are provided so as to roll freely between the inner peripheral surface of the shell-type outer ring and the outer peripheral surface of each shaft portion.
Furthermore, each said seal ring closes the opening part of each said shell type needle bearing, and reinforces the base part of an elastic material with an annular cored bar, respectively. Then, with each base portion being fitted and supported on the base portion of each shaft portion, the end edge of the seal lip provided on each elastic member is connected to each arm portion on the other axial end side of each shell type outer ring. The outer surface of the portion protruding from the inner surface is slid over the entire circumference.

In particular, in the cross shaft type universal joint according to the present invention, each of the seal rings is provided with three seal lips, and the tip edge of each of the seal lips is respectively connected to the shell type outer ring. The outer surface is in sliding contact with the entire circumference.
Further, the one of the outer surface of the portion projecting from the inner surface of the respective arm portions in the axial direction other end side of the shell type outer ring, before Symbol outermost of sliding contact with the outer peripheral surface of the cylindrical portion among the respective seal lips The outer surface of the inward flange portion and the outer surface of the continuous portion of the inward flange portion and the cylindrical portion, which are portions where the tip edges of the two seal lips excluding the seal lip are in sliding contact, are coated films for improving corrosion resistance. and cracks covered by, and the outer peripheral surface of the cylindrical portion leading edge of the outermost sealing lip is in sliding contact portion is not covered by the coating.

Preferably, when carrying out the present invention as described above, the outer peripheral surface of the cylindrical portion, which is the portion where the tip edge of the outermost seal lip is slidably contacted , as in the invention described in claim 2 , is corrosion resistant. It can cover with the chemical conversion treatment film which has.
Further, when practicing the present invention, such as described above, prior Symbol the entire outer surface of each shell type outer ring can also be covered by the chemical conversion coating having corrosion resistance. And the chemical conversion treatment film is exposed to the portion of the outer surface of each shell-type outer ring that is fitted into each of the circular holes and contacts the inner peripheral surface of each of the circular holes .
Further, the pre-Symbol bottom plate portion is present inside the circular holes, it is also possible to cover the outer surface of the bottom plate portion by coating for improving the corrosion resistance.

According to the cruciform universal joint of the present invention configured as described above, even if the use conditions are severe, the cruciform shaft type that makes it difficult for foreign matter to enter the inside of the shell-type outer ring and ensures sufficient durability. A universal joint can be realized.
In other words, since there are three seal lips constituting the seal ring, even if the usage conditions are particularly severe, foreign matter such as dust can be removed from the sliding contact portion between the tip edge of these three seal lips and the outer surface of the shell type outer ring. The possibility of passing through the inside of the shell type outer ring is low. Moreover, among the outer surface of the shell type outer ring, before Symbol the inward flange is two parts leading edge comes into sliding contact of the seal lip of excluding the outermost seal lip sliding contact with the outer peripheral surface of the cylindrical portion among the respective seal lips outer surface and the outer surface of the continuous portion between the cylindrical portion and the inward flange portion of the section is, because it is covered by the coating film for corrosion resistance improvement, the rust generated in the outer surface of the shell type outer ring, before Symbol 2 It is possible to suppress the wear of the leading edge of the book seal lip. The terms outermost sealing lip, even if the leading edge is worn, the amount of make up a labyrinth seal, enter the sealing lip side of the front Symbol two foreign object between an outer peripheral surface of the shell type outer ring It can be suppressed. As a result, the effect of preventing entry of foreign matter into the shell-type outer ring by the three seal lips can be maintained well over a long period of time, and the durability of the cross shaft universal joint can be sufficiently secured .

Further, in the case of the invention described in claim 2, since the rusting of the portion of the outer peripheral surface of the cylindrical portion where the tip edge of the outermost seal lip is in sliding contact can be suppressed, it is advantageous from the viewpoint of ensuring durability. Become.
Also, as discussed previously, if prior Symbol adopt a structure covered by each shell type outer ring entire Kasei treated film outer surface of, thereby the whole rust outer surface of the shell type outer ring.
Furthermore, if the structure in which the bottom plate portion is present inside the circular hole and the outer surface of the bottom plate portion is covered with a coating film for improving corrosion resistance , the durability of the bottom plate portion of each shell type outer ring, It can be further improved.

FIG. 3 is a cross-sectional view of a main part showing a first example of an embodiment of the present invention. The upper left enlarged view of FIG. The figure similar to FIG. 2 which shows the 2nd example of embodiment of this invention. The figure similar to FIG. 2 which shows the 3rd example. The figure similar to FIG. 2 which shows the 4th example. The figure similar to FIG. 2 which shows the 5th example. The partial cut side view which shows one example of the conventional structure of a universal joint in the state which abbreviate | omitted one part. The principal part sectional drawing which shows the condition where the front-end | tip edge part of the seal lip which comprises a seal ring wears with corrosion of the outer surface of a shell type outer ring | wheel according to the order of advancing. Sectional drawing which shows the principal part which shows the 1st example of the specific structure of a prior invention. The principal part sectional view showing the 2nd example. The principal part sectional view showing the 3rd example.

[First example of embodiment]
1 and 2 show a first example of an embodiment of the present invention corresponding to claims 1 and 2 . The feature of this example is that the structure of the seal ring 14a composed of the cored bar 15 and the elastic material 16a that covers the space between the shaft 8 of the cross shaft 3 and the opening of the shell type outer ring 9 is devised. The point is that a necessary portion of the outer surface of the shell type outer ring 9 is covered with a coating film 21b for rust prevention. Since the basic structure of the entire cross shaft universal joint is the same as that of the conventional structure shown in FIG. 7, the illustration and explanation of the equivalent parts are omitted or simplified. The description will focus on the features of the example.

  The seal ring 14a constituting the cross shaft type universal joint of this example includes, in order from the inner space 23 side where the needles 10 and 10 are arranged, a thrust seal lip 18 as an inner seal lip, an intermediate seal lip 22, Three seal lips 18, 22, and 17a are provided with a radial seal lip 17a that is an outer seal lip. The leading edges of the seal lips 18, 22, and 17a are in sliding contact with the outer surface of the shell-type outer ring 9 over the entire circumference. That is, the radial seal lip 17a is formed at the leading edge of the thrust seal lip 18 on the outer surface of the inward flange 13 and the distal edge of the intermediate seal lip 22 at the continuous portion of the inward flange 13 and the cylindrical portion 11. The tip edge of each is elastically slidably contacted with the outer peripheral surface of the cylindrical portion 11 over the entire circumference.

  Further, the thrust seal lip 18 and the middle of the outer surface of the shell-type outer ring 9 on the side of the opening end where the inward flange portion 13 is formed and projecting from the inner surface of the arm portion 5a of the yoke 2a. The portion where the tip edge of the seal lip 22 is in sliding contact is covered with a coating film 21b for improving corrosion resistance. That is, the coating film 21 b is coated on the outer surface of the inward flange 13 and the outer surface of the continuous portion of the inward flange 13 and the cylindrical portion 11. Of the outer peripheral surface of the cylindrical portion 11, the portion of the radial seal lip 17 a that is out of the continuous portion and in contact with the leading edge of the radial seal lip 17 a is not covered with the coating film 21 b. The outer surface of the shell type outer ring 9 does not necessarily need to be covered with a chemical conversion treatment film having corrosion resistance as in the above-described invention, but is preferably covered. In the case of this example, a coating film 21a is applied to the outer surface of the bottom plate portion 12 of the outer surface of the shell-type outer ring 9 as in the second to third examples of the specific structure of the above-described invention. Forming.

According to the cruciform universal joint of the present example configured as described above, even when the usage conditions are severe, it is difficult for foreign matter to enter the inside of the shell-type outer ring 9, and it is easy to ensure sufficient durability. A type universal joint can be realized.
That is, in the structure of this example, the two seal lips 18 and 22 of the thrust seal lip 18 and the intermediate seal lip 22 are replaced with the two seal lips 17 and 18 ( For example, it functions similarly to FIG. And it can prevent that the abrasion of the front-end | tip edge of the said 2 seal lips 18 and 22 advances by friction with the surface of the said shell type outer ring | wheel 9 roughened by rust.

  Furthermore, in the case of the structure of this example, the possibility that foreign matter existing in the external space enters the internal space 23 can be further reduced based on the presence of the radial seal lip 17a located on the outermost side. In particular, in the case of the structure of this example, the distal end edge of the radial seal lip 17a is a cylindrical surface portion of the outer peripheral surface of the cylindrical portion 11 constituting the shell type outer ring 9 and whose outer diameter does not change in the axial direction. It is in sliding contact. For this reason, even when the positional relationship in the axial direction between the seal ring 14a and the shell type outer ring 9 slightly changes during torque transmission by the cross shaft type universal joint, the leading edge of the radial seal lip 17a and the shell type outer ring The surface pressure of the sliding contact portion with the outer peripheral surface of 9 does not change. In other words, fluctuations in the axial gap between the inner surface of the bottom plate portion 12 of the shell type outer ring 9 and the tip end surface of the shaft portion 8 (including not only positive gaps but also zero or slight negative gaps) Regardless of the axial displacement of the seal ring 14a and the shell-type outer ring 9 based on the elastic deformation of the bottom plate portion 12, the surface pressure of the sliding contact portion between the tip edge and the outer peripheral surface can be prevented from changing. . For this reason, the sealing performance by the radial seal lip 17a can be satisfactorily and stabilized.

  Note that the radial edge of the radial seal lip 17a is in sliding contact with a portion of the outer surface of the shell-type outer ring 9 that is not covered with the coating film 21b. , Foreign matter floating in the external space is likely to adhere. For this reason, there is a possibility that the tip edge portion of the radial seal lip 17a is worn due to property change (rusting) on the outer peripheral surface of the shell-type outer ring 9 or biting of foreign matter. However, even when the tip edge is worn, a labyrinth seal is formed between the tip edge of the radial seal lip 17a and the outer peripheral surface of the shell type outer ring 9. Therefore, even when the tip edge of the radial seal lip 17a is worn, the amount of foreign matter entering the two seal lips 18 and 22 can be suppressed. As a result, the amount of foreign matter reaching the sliding contact portion between the intermediate seal lip 22 and the thrust seal lip 18 and the outer surface of the shell-type outer ring 9 can be reduced, and the effect of preventing foreign matter from entering the internal space 23 is long. It can be maintained well over the period, and the durability of the cross shaft universal joint can be sufficiently secured. Further, if the outer surface of the shell type outer ring 9 is covered with the chemical conversion coating, rusting of the portion of the outer peripheral surface of the cylindrical portion 11 where the tip edge of the radial seal lip 17a is in sliding contact can be suppressed. It is advantageous from the aspect of securing.

[Second Example of Embodiment]
FIG. 3 also shows a second example of an embodiment of the present invention corresponding to claims 1 and 2 . In the case of this example, two ridges 24a and 24b are respectively provided on portions facing the outer peripheral surface of the cylindrical portion 11 of the shell type outer ring 9 at the tip edge portion of the radial seal lip 17b provided on the elastic material 16b. It is formed in a state separated from each other in the axial direction over the entire circumference. With the seal ring 14b incorporated in the universal joint, the protrusion 24a on the distal end side of the protrusions 24a, 24b is in sliding contact with the outer peripheral surface of the cylindrical portion 11, and the distal end edge of the protrusion 24b on the proximal end side Is slightly separated from the outer peripheral surface.

In the case of such a structure of the present example, the proximal end that has been separated from the outer peripheral surface of the cylindrical portion 11 until the protrusion 24a on the distal end side is worn with use over a long period of time. The side protrusion 24b is in sliding contact with the outer peripheral surface. As a result, the sealing performance by the radial seal lip 17b can be ensured more sufficiently over a long period of time.
Since the configuration and operation of the other parts are the same as in the first example of the embodiment described above, overlapping illustrations and descriptions are omitted.

[Third example of embodiment]
FIG. 4 also shows a third example of the embodiment of the invention corresponding to claims 1 and 2 . In the case of this example, a ridge 25 formed on the outer edge of the shell-type outer ring 9 at the tip edge of the intermediate seal lip 22a provided on the elastic member 16c constituting the seal ring 14c is entirely formed on the outer surface. It is slid over the circumference. In the case of such a structure of this example, the sliding contact state between the front end edge of the intermediate seal lip 22a and the outer surface of the shell type outer ring 9 is stabilized (the surface pressure of the contact portion is appropriately secured). ), Sealing performance can be improved.
Since the configuration and operation of other parts are the same as those in the first example of the above-described embodiment, overlapping illustrations and descriptions are omitted.

[Fourth Example of Embodiment]
FIG. 5 also shows a fourth example of an embodiment of the present invention corresponding to claims 1 and 2 . In the case of this example, the shapes of the thrust seal lip 18a and the intermediate seal lip 22b are different from those of the above-described embodiments. Specifically, both of these seal lips 18a and 22b have a bifurcated shape with a common base end.
Since the configuration and operation of other parts are the same as those in the first example of the above-described embodiment, overlapping illustrations and descriptions are omitted.

[ Reference example ]
FIG. 6 shows a reference example related to the present invention. In the case of this reference example, the thrust seal lip of the outer surface of the portion protruding from the inner surface of the arm portion 5a of the yoke 2a on the opening end portion side of the shell type outer ring 9 where the inward flange portion 13 is formed. 18 and the portion where the tip edge of the radial seal lip 17a is slidably contacted are covered with a coating film 21c for improving corrosion resistance. For this reason, among the causes of wear of the tip edge of the radial seal lip 17a, it is possible to prevent changes in the properties (rusting) of the outer peripheral surface of the shell type outer ring 9. Although wear due to the biting of foreign matter cannot be prevented, durability can be improved as much as wear due to property changes can be prevented. In the case of this reference example, as in the first and third examples of the prior invention shown in FIGS. 9 and 11, the outer end in the axial direction of the coating film 21c is placed inside the circular hole 6a (6b). It is preferable to make it exist in the position which penetrates a little (for example, 0.5 mm-1 mm).
Since the configuration and operation of other parts are the same as those in the first example of the above-described embodiment, overlapping illustrations and descriptions are omitted.

  In the present invention, a lot of foreign matters such as muddy water are likely to adhere, the operation speed is fast, and the friction speed between the tip edge of the seal lip and the outer surface of the shell type outer ring is fast. A great effect can be obtained by applying it to a cross joint universal joint for a propeller shaft that is subject to usage conditions. However, the present invention is not limited to the propeller shaft, but can also be applied to a cross shaft type universal joint used for a purpose other than that for a steering device and for an automobile.

DESCRIPTION OF SYMBOLS 1 Universal joint 2a, 2b Yoke 3 Cross shaft 4 Shell type needle bearing 5a, 5b Arm part 6a, 6b Circular hole 7 Connection base part 8 Shaft part 9 Shell type outer ring 10 Needle 11 Cylindrical part 12 Bottom plate part 13 Inward flange part 14, 14a , 14b, 14c Seal ring 15 Core metal 16, 16a, 16b, 16c Elastic material 17, 17a, 17b Radial seal lip 18, 18a Thrust seal lip 19, 19a Rust 20, 20a Crevice 21, 21a, 21b, 21c Coating film 22 , 22a, 22b Intermediate seal lip 23 Internal space 24a, 24b Projection 25 Projection

Claims (2)

Each of the yokes is formed concentrically at a pair of yokes formed in a bifurcated shape, each having a pair of arms, and at the tips of the arms, which are both ends of the yokes. Each pair of yokes has a total of four circular holes and four shafts radially fixed on the outer peripheral surface of the coupling base, and these shafts are inserted into the circular holes. In this state, the cross shaft combined with the two yokes, four shell type needle bearings provided between the outer peripheral surface of each shaft portion and the inner peripheral surface of each circular hole, and each shell 4 seal rings that close the opening of the needle bearing
Each shell needle bearings, respectively, made of a metal plate, wherein the shell type outer ring is internally fitted fixed to the circular holes, between the inner peripheral surface and the outer circumferential surface of the shaft portion of the shell type outer ring A plurality of needles provided so as to be freely rollable, and a shell-type outer ring includes a cylindrical portion that is fitted and fixed inside each circular hole, and an axial direction of the cylindrical portion. Of the both end portions, the bottom plate portion that covers the entire one end side that is the outer surface side of each arm portion, and the cylindrical portion that is the inner surface side of each arm portion is bent radially inward from the other axial end side. With an inward saddle
Each of the seal rings has a base portion of an elastic material reinforced by an annular cored bar, and each seal ring is provided on each elastic material in a state where the base portion is externally supported by the base portion of each shaft portion. A cruciform universal joint in which the tip edge of the lip is in sliding contact with the entire outer surface of the portion protruding from the inner surface of each arm at the other axial end of each shell type outer ring. In
Each of the seal rings is provided with three seal lips, and the tip edges of the seal lips are in sliding contact with the outer surface of the shell-type outer ring over the entire circumference.
The outermost seal lip sliding said one of the outer surface of the portion projecting from the inner surface of the arms at the other axial end side of each shell type outer ring, the outer peripheral surface of the cylindrical portion among the front Symbol respective seal lips The outer surface of the inward flange portion and the outer surface of the continuous portion of the inward flange portion and the cylindrical portion, which are the portions where the tip edges of the two seal lips excluding slidably contact , are covered with a coating for improving corrosion resistance. The cross shaft type universal joint is characterized in that an outer peripheral surface of the cylindrical portion, which is a portion where the tip edge of the outermost seal lip is in sliding contact, is not covered with the coating film . 2. The cross shaft universal joint according to claim 1, wherein an outer peripheral surface of the cylindrical portion, which is a portion in which a tip edge of the outermost seal lip is in sliding contact, is covered with a chemical conversion coating having corrosion resistance .

Images