JPH0724661Y2 - Cardan fittings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a cardan joint that supports a cross shaft by a bearing fitted in a bearing hole provided in a yoke.

[Prior art]

Conventionally, as a cardan joint, as shown in FIG. 5, the cup bottom of the bearing 3'and the end face 21A 'of the shaft portion of the cross shaft are not in contact with each other, and the seal body 4'has both the function of sealing and the function of receiving thrust. Are known. In this case, the seal body 4'has to have a high rigidity in order to support the thrust load.
The load changes greatly with respect to the axial displacement of the bearing, and a gap is created between the bearing 3'and the seal body 4'due to variations in the parts precision or assembly precision of the cross shaft, the yoke, and the bearing.
There is a problem that the seal body 4'is overloaded and the seal performance and the torque performance vary greatly. If the rigidity is low, excessive torque will not be generated due to variations in parts accuracy and assembly accuracy, but the deflection of the sealing body 4'due to thrust load will be large, and the amount of component force during rotation will increase the amount of axial movement of the cross shaft. When one seal body is compressed but the other seal body has a reduced thrust load, the seal body 4'cannot follow the seal body 4'and the seal body 4'is separated from the bearing 3 '. Is significantly reduced.

For this reason, conventionally, the rigidity of the seal body 4'has been set such that the load relatively slowly increases with respect to the initial compressive deformation, and the load sharply increases when the amount of compressive deformation exceeds a certain amount. In order to reduce the variation in the sealing performance, the variation in the compression amount of the seal body 4'in the assembly is reduced.
That is, the precision of each part and the precision of assembly are improved.

As another example, there is also known a structure in which the bottom surface of the bearing cup is brought into contact with the end surface of the cross shaft portion to receive a thrust load. Normally, the end surface of the cross shaft portion and the bearing cup bottom are assembled during assembly. It is assembled with preload.

[Problems to be solved by the device]

Among the above-mentioned conventional cardan joints, the type shown in FIG.
Since it is necessary to improve the assembling accuracy, the cost becomes high, and when an excessive thrust load is applied, the deflection of the seal body 4'is large, so that the sealing performance is deteriorated for the above reason. Since the seal body 4'has a thrust load, its rigidity cannot be lowered so much, and therefore the bending torque cannot be reduced to a certain value or less. There is a problem that is likely to occur.

In the latter type, in which the bottom surface of the cup of the bearing is in contact with the end surface of the cross shaft part, the preload amount at the time of assembly varies due to variations in the precision of each part and the assembly precision. When used as a steering joint, problems such as torque fluctuation of the steering wheel and poor return occur, and when the preload amount is small, a minute gap occurs due to wear during use, and the end face of the cross shaft part and the bearing cup An abnormal noise was generated due to the contact with the bottom, and this abnormal noise was transmitted to the steering wheel, giving the driver an unpleasant feeling.

As a solution to this, when the preload amount is large, the yoke is hit with a hammer to move the bearing by a small amount to adjust the preload amount. This means has a drawback that it requires man-hours and cost, and it is difficult to obtain an appropriate amount of preload.

When the amount of preload is small, it is proposed that a resin plate be inserted between the end face of the cross shaft part and the cup bottom face of the bearing to prevent abnormal noise even when a minute gap occurs. In this case, the problem of a large amount of preload is hardly solved, and the effect of improving the problem of variation in the amount of preload is small in proportion to the increase in cost.

As a solution to a large torque due to a large amount of preload, a type has been proposed in which a protrusion is provided in the center of the bottom surface of the bearing cup to contact the end face of the cross shaft part. There was a drawback that cracks tended to occur.

On the other hand, it has been proposed to interpose a spring, which is an elastic body, between the two, but since the amount of spring deflection and the compressive load have a relationship that changes in a generally linear manner, variations in part dimensions and variations in assembly may cause With a relatively weak spring satisfying a torque range in which the amount of preload varies, it is difficult to obtain a cardan joint having a good sealability within that range.

Furthermore, the shaft mounting hole of the yoke that attaches the yoke to the spline shaft is slid in the axial direction, and in a cardan joint in which this part is fastened with a bolt to fix the yoke to the shaft, the yoke is deformed by tightening the bolt. Since the position of the bottom surface of the cup of the bearing with respect to the end surface of the cross shaft portion is displaced, the axial preload tends to increase, the frictional resistance tends to increase, and torque failure tends to occur.

The present invention has been made to solve the drawbacks of the conventional cardan joint, and an object thereof is to provide a cardan joint that can be efficiently assembled and has a small bending torque and a good sealing property. Is.

[Means for Solving the Problems]

To achieve this object, the present invention provides a cardan joint in which the shaft diameter portions at both ends of the cross shaft are supported by cup-shaped bearings that are fitted in the bearing holes of the opposing yokes, respectively, and the cross shaft has a shaft diameter portion. Has a bottomed axial hole that opens to the end face of
The axial hole has a synthetic resin pin fitted so as to protrude from the end face of the axial diameter portion, and the pin has a large outer diameter smaller than the inner diameter of the axial hole at both ends of the small diameter portion. A radial portion is formed, and subsequently to each large diameter portion, a substantially frustoconical projection is formed at the axially outer end thereof, and an axially slidable inner surface of the axial hole is formed on the outer periphery of each large diameter portion. A plurality of protrusions extending in the axial direction that fit with different tolerances are formed, and further, each of the protrusions has an outer end in the axial direction between the protrusion having the substantially truncated cone shape and the large diameter portion. It is drawn axially inward from the connecting edge, and its axial inner end extends in the radial direction along the inner step surface between the large diameter portion and the small diameter portion, and the tip projection of the pin is It is designed to be pressed against the bottom of the cup of the bearing.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

The cross shaft 2 has a cylindrical shaft diameter portion 21 protruding in all directions, and the bottom portion of the shaft diameter portion 21 has a bottomed axial hole 22 that opens to the end face.
Are formed respectively. A grease supply hole having a small diameter may be opened on the bottom surface of the axial hole 22 to supply grease from the axial hole 22 to the bearing portion, but this embodiment is an example in which there is no grease supply hole.

The pin 5 is made of synthetic resin and has a small diameter portion 51 in the axial center,
There are large diameter portions 52, 52 on both sides thereof. A protrusion having a tapered conical surface 53 is formed on the outside of the large diameter portion 52. Further, the large-diameter portions 52, 52 each have a plurality of, in the illustrated embodiment, four protrusions 54 extending in the axial direction formed on the outer peripheral surface thereof. The tip 54a of each protrusion 54 is drawn slightly inward from the edge of the outer end of the large diameter portion 52, 52, that is, the connecting edge between the large diameter portion and the conical surface 53 of the protrusion. As shown in FIG. 1, the axially inner end of each ridge 54 extends radially along the axially inner step surface of the large diameter portion 52 to the outer peripheral position of the small diameter portion, whereby the ridge 54 is formed.
Has been reinforced. The large-diameter portion 52 of the pin 5 is slightly smaller than the inner diameter of the axial hole 22 of the cross shaft 2, and the ridge 54 on the outer periphery thereof.
The outer side of the is fitted in the axial hole 22 and is slidable in the axial direction along the inner surface of the hole. In the pin 5 fitted in the axial hole 22 in this manner, both the projections 54 are in contact with the axial hole 22 as shown in FIGS. 2 and 3, and the projection at the tip of the pin is the axial diameter portion 21. Protruding from the end face of. Pin 5 in the illustrated embodiment
Has a symmetrical shape, and therefore, no matter which end the end portion is inserted into the axial hole 22, the positional relationship does not change, and there is no complication during assembly work. Also, since the tip of the protrusion 54 is retracted rearward, it is easy to press fit it into the axial hole 22,
Moreover, even if there is some variation in the hole diameter of the axial hole 22, the press-fitting operation of the pin 5 is small due to the ridge 54 and the change in the press-fitting is small, so that the press-fitting work becomes easy.

An example of the load-displacement curve when the pin 5 is compressed will be described with reference to FIG.

When the load-displacement of the pin 5 is examined by taking the compressive displacement of the pin on the horizontal axis and the compressive load on the vertical axis, the displacement increases with the increase of the load from the origin O because the pin 5 is made of synthetic resin. From the vicinity of the load A, the load-displacement curve becomes gentle and changes to the point C. When the load is removed at this point C, it drops rapidly and reaches point D. That is, it can be seen that this pin has a permanent deformation from the origin O to the point D, and the deformation of the pin is accompanied by plastic deformation. The fact that the displacement at point C has returned to point D means that the pin 5 also has elastic deformation. Therefore, when a compressive load is applied again to the pin deformed to the point D, it follows almost the same path as when it descends from the point C to the point D, and the displacement 1 is an elastic body although the load and the displacement are relatively small. It has the property of

In the assembly of the cardan joint of the present invention, the pin 5 is inserted into the axial hole 22, one end of the pin 5 is brought into contact with the bottom of the axial hole 22, and the seal body 4 is fitted to the shaft diameter portion 21, The seal body 4 is brought into contact with the step portion with the cross shaft main body, then the bearing hole of the yoke 1 and the shaft diameter portion 21 of the cross shaft are aligned with each other, and the bearing 3 is press-fitted into the bearing hole of the yoke 1. First, the cup bottom surface of the bearing 3 is not in contact with the projection of the pin 5 as shown in FIG. 2, but as the bearing 3 is press-fitted, the cup bottom surface comes into contact with the projection of the pin, and the bearing 3 is continuously press-fitted. 3, the small diameter portion 51 of the pin 5 is deformed, and the bearing 3 is press-fitted into the bearing hole of the yoke 1 by a predetermined amount, as shown in FIG.
, The small diameter portion 51 of the pin 5 is plastically deformed.

In this case, when the pin 5 is used as a steering joint, the maximum thrust load has a size shown by A in FIG. 4, and the minimum load that causes a crack in the cup bottom of the bearing 3 has a size shown by B in FIG. Have been chosen as.

[Effect of device]

The cardan joint of the present invention configured as described above is provided with a bottomed axial hole that opens at the end surface of the shaft diameter portion of the cross shaft, and is made of synthetic resin that projects from the end surface of the shaft diameter portion. A large diameter portion is formed at both ends of the small diameter portion by fitting a pin, making the pin symmetrical, and having a ridge on the outer periphery that is slidable in the axial direction along the inner surface of the axial hole and is outside the large diameter portion. By providing a tapered projection on one side and engaging the projection of this pin with the cup bottom of the bearing, plastic deformation is caused in the small diameter part of the pin, so it is the maximum when using as a steering joint. If the pin is assembled with a load region intermediate between the thrust load A and the minimum load B at which cracks occur in the cup bottom of the bearing, the load corresponds to the range of L in Fig. 4, the plasticity of the small diameter part of the pin Preload does not increase due to deformation , Even if there are variations in parts accuracy and variations in assembly, this variation is effectively absorbed, a cardan joint with a small torque that does not cause excessive torque is obtained, and the thrust load is supported by the pin, so the seal body Since it is not necessary to receive a thrust load, a material having high elasticity can be used for the seal body, and a seal body having good sealing performance can be used, so that a cardan joint having good sealing performance can be obtained. Even if there is variation in the diameter of the axial hole of the cross shaft, the pin pressure input is small and stable, so press-fitting and assembly are easy, and variation in compression load is reduced.

Also, since the pin is symmetrical, it is not necessary to select the direction when inserting it into the axial hole of the cross shaft, and since the end of the pin is a tapered protrusion, friction with the cup bottom is small. it can.

As a result, in the case of the cardan joint of the present invention, compared to the conventional joint shown in FIG. 5, it was possible to obtain a cardan joint having a sealability of 3 times or more and a maximum torque of 1 / 2.6 or less.

As described above, according to the present invention, it is possible to easily obtain a cardan joint which is easy to assemble, has a small torque, and has a good sealing performance, and even if the pin is slightly worn during use, it can be absorbed by the elasticity of the pin. It is possible to provide a cardan joint that does not generate

[Brief description of drawings]

1 to 4 show an embodiment of the present invention, FIG. 1 is a front view of a pin, FIG. 2 is a cross-sectional view of a main part of a cardan joint showing a state in which a bearing is being press-fitted, and FIG. FIG. 4 is a cross-sectional view of a main part of a conventional cardan joint, FIG. 4 is a view showing an example of a load-displacement curve when a pin is compressed, and FIG. . Explanation of symbols, 1 ... Yoke, 2 ... Cross shaft, 3 ... Bearing, 4 ... Seal, 5 ... Pin, 21 ... Shaft diameter part, 22 ... Axial hole, 51 ...
… Small diameter part, 52 …… Large diameter part, 53 …… Cone surface, 54 …… Ridge.

Claims (1)

[Scope of utility model registration request] 1. A cardan joint in which a shaft-shaped portion at both ends of a cross shaft is supported by cup-shaped bearings respectively fitted in bearing holes of opposing yokes, the cross shaft being open at an end face of the shaft diameter portion. There is a bottomed axial hole, and the axial hole has a synthetic resin pin fitted so as to project from the end surface of the shaft diameter portion, and the pin is provided at both ends of the small diameter portion with the shaft. A large-diameter portion having an outer diameter smaller than the inner diameter of the direction hole is formed, and subsequently to each of the large-diameter portions, a substantially frustoconical projection is formed at the outer end in the axial direction, and the outer periphery of each of the large-diameter portions is A plurality of ridges extending in the axial direction are formed on the inner surface of the axial hole so as to fit with a slidable tolerance in the axial direction. Further, each of the ridges has an outer end in the axial direction of the substantially truncated cone shape. Is drawn inward in the axial direction from the connecting edge between the protrusion and the large diameter portion, and the inner end in the axial direction is the large diameter portion and the small diameter portion. Extends radially along the inner stepped surface between, cardan joint, characterized in that said pin tip projection is pressed against the cup bottom of the bearing.