JP5083157B2 - Telescopic rotation transmission shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure low in cost and hardly causing damage such as indentation even when transmitting large turning force (torque). <P>SOLUTION: Partial (two) recessed groove pairs out of recessed groove pairs each composed of an outer side recessed groove 24 and an inner side recessed groove 25 forming a pair, are provided with only balls 26, 26. The remaining (two) recessed groove pairs are provided with only cylindrical rollers 27, 27 smaller in outer diameter than the balls 26, 26. The surfaces of the balls 26, 26 are brought into contact with groove bottom parts of the inner surfaces (inner side faces) of the outer side and inner side recessed grooves 24, 25, and the outer peripheral surfaces of the cylindrical rollers 27, 27 are brought into contact with the vicinity of shoulder parts of the inner surfaces (inner side faces) of the outer side and inner side recessed grooves 24, 25. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The telescopic rotation transmission shaft according to the present invention is capable of transmitting rotational force (torque), such as a steering shaft and an intermediate shaft (intermediate shaft) constituting an automobile steering device, and can extend and contract in the axial direction. Used as a shaft.

  The steering apparatus for an automobile is configured as shown in FIG. 22, for example, so that the movement of the steering wheel 1 is transmitted to the steering gear unit 2. The movement of the steering wheel 1 is transmitted to the input shaft 6 of the steering gear unit 2 through the steering shaft 3, the universal joint 4a, the intermediate shaft 5, and the universal joint 4b. Then, the steering gear unit 2 pushes and pulls the pair of left and right tie rods 7 and 7 to give a desired steering angle to the steered wheels. In the example shown in FIG. 22, an electric power steering device is incorporated in which the electric motor 8 applies an assisting force corresponding to the force applied to the steering wheel 1 by the driver to the steering shaft 3.

  When the front-rear position of the steering wheel 1 is adjusted according to the physique and driving posture of the driver with the steering device as described above, the steering shaft 3 and the steering column 9 that rotatably supports the steering shaft 3 are used. And extend and contract. For this purpose, the steering shaft 3 is a so-called telescopic steering shaft in which the outer shaft 10 and the inner shaft 11 are freely combined with expansion and contraction and transmission of rotational force by a spline engaging portion. Further, the steering column 9 is a combination of an outer column 12 and an inner column 13 that can be expanded and contracted.

  In order to improve the operational feeling of the steering wheel 1 in a normal state, it is necessary to prevent the rotational direction from rattling in the axial sliding portion such as the spline engaging portion of the steering shaft 3. There is. On the other hand, in order to be able to adjust the front-rear position of the steering wheel 1 with a light force, the axial sliding portion needs to be configured to be easily displaced in the axial direction. Conventionally, a structure described in Patent Document 1 is known as a structure that satisfies such conflicting requirements. 23 to 24 show an example of the conventional structure described in Patent Document 1. FIG.

  In the case of the steering shaft 3a having the conventional structure, an outer shaft 10a, an inner shaft 11a, a plurality (three pieces) of steel balls 14, 14, a cage 15, an elastic member (plate spring) 16, and a plurality (Two) cylindrical members 17 and 17 are provided. Of these, the outer shaft 10a is provided with a plurality of (three) outer-side grooves 18 and 18 in the axial direction in a state of being recessed radially outward from the inner peripheral surface. . The inner shaft 11a is provided with a plurality of (three) inner-side grooves 19 and 19 in the axial direction on the outer peripheral surface so as to be recessed radially inward from the outer peripheral surface. Each of the steel balls 14 and 14 corresponds to a “transmission piece” and a “ball” recited in the claims, and is one of the three outer side grooves 18 and 18 (see FIG. 23) and the elastic member 16 engaged with the inner side concave groove 19 facing the outer side concave groove 18.

  The cage 15 holds the steel balls 14 and 14 at predetermined intervals in the axial direction of the outer shaft 10a and the inner shaft 11a. The elastic member 16 elastically presses the steel balls 14 and 14 toward the outer groove 18 (applies a preload). The cylindrical members 17 and 17 correspond to the “transmission piece” and the “cylindrical roller” recited in the claims, and are the same as the other two outer concave grooves 18 and 18. They are respectively provided between the remaining two inner side concave grooves 19, 19.

  Then, by elastically pressing the steel balls 14, 14 against the inner surface (inner side surface) of the (one) outer groove 18 by the elastic member 16, the steel balls 14, 14 and the It is possible to prevent rattling from occurring at the engaging portions (contact portions, meshing portions) between the cylindrical members 17 and 17 and the outer and inner concave grooves 18 and 19. Further, when a large rotational force (torque) is transmitted between the outer shaft 10a and the inner shaft 11a, the elastic member 16 is elastically deformed in accordance with the rotational force. And based on such elastic deformation of the elastic member 16, the large rotational force is transmitted through the cylindrical members 17, 17, and the steel balls 14, 14 and the outer side, It prevents that the surface pressure of the contact part with each inner side ditch | groove 18 and 19 becomes excessive. When the outer shaft 10a and the inner shaft 11a are relatively displaced in the axial direction, the steel balls 14 and 14 roll, and the outer peripheral surfaces of the columnar members 17 and 17 and the outer side. The inner grooves (inner surfaces) of the inner grooves 18 and 19 slide. For this reason, the relative displacement can be performed with a light force.

  However, in the case of the structure described in Patent Document 1 as described above, the number of parts is increased by the provision of the elastic member 16, and the production of parts and management are troublesome. In addition, the number of assembling steps is increased, and the assembly work is increased. This may lead to an increase in the manufacturing cost of the steering shaft 3a. On the other hand, as a structure in which the relative displacement can be performed with a light force without providing the elastic member 16 as described above, for example, structures described in Patent Documents 2 to 8 have been conventionally known. However, in the case of the structures described in these Patent Documents 2 to 8, the rotational force is transmitted only with the steel balls. For this reason, at the time of steering, these steel balls are repeatedly pressed against the same part of the outer and inner concave grooves that engage with these steel balls, and the surface pressure of the part may become excessively large. is there. And when surface pressure becomes large too much like this, an impression (plastic deformation) may arise in the said part. Such an indentation is not preferable because it causes rattling during steering and may cause the relative displacement in the axial direction between the outer shaft and the inner shaft to be smoothly disabled.

  The indentation is more likely to occur as the rotational force (torque) to be transmitted increases. For example, the steering device shown in FIG. 22 is a so-called column-type electric power steering device in which the electric motor 8 as an auxiliary power source is provided on the steering column side. Such an electric power steering device. In this case, the rotational force transmitted by the intermediate shaft 5 is increased by the amount of auxiliary power compared to the rotational force transmitted by the steering shaft 3. Therefore, when the above-described techniques described in Patent Documents 2 to 8 are adopted for such an intermediate shaft 5 (shaft to which auxiliary power is applied, shaft downstream of the auxiliary power source), Furthermore, it becomes easy to occur.

International Publication No. 2003/031250 Pamphlet JP 2006-349104 A JP 2007-46769 A JP 2007-16901 A Japanese Patent No. 3694637 Japanese Utility Model Publication No. 3-30621 JP 2004-306919 A JP 2004-168229 A

  In view of the circumstances as described above, the telescopic rotation transmission shaft according to the present invention is inexpensive, and it is desirable to realize a structure that can hardly cause damage such as indentation even when a large rotational force (torque) is transmitted. Invented.

The telescopic rotation transmission shaft of the present invention includes an inner shaft, an outer shaft, and a plurality of transmission pieces as in the conventional structure described above.
Among these, the inner shaft is provided with inner side concave grooves, which are recessed radially inward, at a plurality of positions in the circumferential direction on the outer peripheral surface in the axial direction.
Further, the outer shaft can be inserted into the inner shaft, and the outer side groove is recessed radially outward at a position aligned with the inner side groove at a plurality of positions on the inner circumferential surface. Are provided in the axial direction.
Each transmission piece is provided between each inner groove and each outer groove.
And the said outer shaft and the said inner shaft are combined so that transmission of the rotational force (torque) between each other and the relative displacement of an axial direction are possible.

  In particular, in the telescopic rotation transmission shaft of the present invention, a part of each of the transmission pieces is a ball and the remaining part is a cylindrical roller. Also, together with this, only the above-mentioned ball is put into the remaining groove portion (remaining portion) of each of the groove sets formed by the inner groove and the outer groove formed in pairs. Not only the entire groove set, but also the case of only a part of the remaining portion. The claims are the same.) Only the cylindrical roller is provided in each of the groove sets (the plurality of groove sets). Only some balls are provided in some of the groove sets, and only cylindrical rollers are provided in the remaining groove sets). Furthermore, a contact portion (in a neutral state where no rotational force is applied) between the surface of the ball and the inner surface (inner surface) of each of the concave grooves on the inner side and outer side (contact portion, engagement portion, meshing portion) A contact portion (abutting portion, contact between the outer peripheral surface and the inner surface based on the rotational force) between the outer peripheral surface of the cylindrical roller and the inner surface (inner surface) of the inner and outer concave grooves. The inner side and outer side grooves are positioned closer to the groove bottom side than the engaging portion and the engaging portion). More specifically, the surface of the ball is brought into contact in the vicinity of the groove bottom portion (more preferably the groove bottom portion) of the inner surfaces of the inner and outer concave grooves, and the surface of the cylindrical roller is contacted with the inner surface. The contact is made in the vicinity of the shoulder portion of the inner surfaces of the concave grooves on the side and outer sides.

In other words, contact angles (in a neutral state where no rotational force is applied) between the surface of the ball and the inner surfaces of the inner and outer concave grooves (both ends of the contact portion between the ball surface and the inner surfaces of the concave grooves) Contact between the outer peripheral surface of the cylindrical roller and the inner surfaces of the inner and outer concave grooves (in a state where the outer peripheral surface and the inner surface are in contact with each other based on rotational force). The angle is larger than the angle (the angle formed by the virtual planes in contact with the contact portion between the outer peripheral surface of the cylindrical roller and the inner surface of each concave groove). That is, the contact angle between the surface of the ball and the inner surface of each groove on the inner side and outer side is increased (oblique angle, more preferably close to 180 degrees), and the outer peripheral surface of the cylindrical roller The contact angle with the inner surface of each of the inner side and outer side concave grooves is made small (a sharp angle, more preferably a value close to 0 degrees).
In any case, the surface of the ball is brought into contact (more preferably, the groove bottom) in the inner surface of each of the inner and outer concave grooves (by increasing the contact angle), and The surface of the cylindrical roller is brought into contact in the vicinity of the shoulder of the inner surface of each of the inner and outer concave grooves (the contact angle is thereby reduced), and as the rotational force increases, the cylindrical roller moves toward the inner side. The outer side grooves are engaged (engaged) so that the rotational force can be transmitted.
Furthermore, in the case of the present invention, an elastic piece for restricting the axial position of the cylindrical roller at both ends of the remaining groove set provided only with the cylindrical roller in the axial direction of the inner shaft and the outer shaft. Is provided. Felt is used as this elastic piece. Then, the felt is impregnated with lubricating oil.

  In the case of carrying out such a telescopic rotation transmission shaft of the present invention, preferably, the outer diameter of the ball is made larger than the outer diameter of the cylindrical roller, as in the invention described in claim 2. Intervals in the circumferential direction between the inner and outer concave grooves and the balls in the circumferential direction of the outer shaft and the inner shaft (this interval is set to 0 when the ball has a tightening margin as described later. The clearance (gap) in the circumferential direction between the inner and outer concave grooves and the cylindrical roller is increased. Further, preferably, with this configuration, when the rotational force is small, only the ball transmits the rotational force based on the engagement (engagement) with the inner and outer concave grooves. In a state where the rotational force is large, along with the elastic deformation of the above-mentioned ball and the inner-side and outer-side concave grooves engaged with this ball {for example, the portion where the ball and the surface of this ball abut (the inner surface of the concave groove being the mating surface) And the cylindrical roller also engages (engages) the inner and outer concave grooves to transmit the rotational force. To.

  Moreover, when implementing such an expansion-contraction type rotation transmission shaft of this invention, Preferably, like the invention described in Claim 3, among the said balls and the said cylindrical rollers, only the ball | bowl, the said inner side, A tightening allowance (including a clearance 0 and a tightening allowance 0) is provided for each groove on the outer side. That is, in the state where the outer shaft and the inner shaft are combined and in a neutral position where no rotational force is applied between the outer shaft and the inner shaft, the inner groove (which constitutes a groove set provided only with balls) The outer diameter of the ball is the same as the diameter of the virtual circle with respect to the diameter of the virtual circle (inscribed circle related to the cross section) formed by the inner surfaces of the concave grooves on the side and outer sides, or (very slightly, For example, it is increased to about 1/100 to 1/1000 of the outer diameter of the ball, or about 1/5 to 1/1000 when the rigidity of the ball or groove is reduced as described later. On the other hand, the outer diameter of the cylindrical roller is set to be larger than the diameter of a virtual circle (inscribed circle related to the cross section) formed by the inner surfaces of the inner side and outer side concave grooves (which constitute a groove set provided with only cylindrical rollers). (Slightly, for example, about 1/100 to 1/1000 of the outer diameter of the cylindrical roller, or about 1/5 to 1/1000 when the rigidity of the ball or groove is reduced as described later).

  The relationship between the tightening allowance to be given to the ball in this way, the outer diameter of the ball, the outer diameter of the cylindrical roller, and the curvature radius (and inclination, etc.) of the cross-sectional shape of each concave groove {outside of the ball The diameter, the outer diameter of the cylindrical roller, the diameter of a virtual circle (inscribed circle related to the cross section) formed by the inner surfaces of the inner and outer concave grooves, and the radius of curvature of the inner and outer concave grooves Relationship} is regulated as follows. First, the tightening allowance of the ball (the difference between the outer diameter of the ball and the diameter of the imaginary circle) is related to the radius of curvature of the cross-sectional shape of each groove (relation with the area of the contact ellipse). Within the range where the inner and outer grooves are elastically deformed, that is, the inner and outer grooves are not indented (plastic deformation) (even if they occur, it does not lead to a decrease in durability, In addition, it is set within a range in which the axial expansion and contraction can be performed smoothly. Further, the outer diameter of the cylindrical roller is made smaller than the outer diameter of the ball, and further, the diameter of the virtual circle, and at the time of transmission of the rotational force, the ball and the inner and outer concave grooves Within the range where the elastic deformation occurs, that is, within the range where no indentation is generated in each of the inner and outer concave grooves (there is no reduction in durability and smooth expansion and contraction in the axial direction). The outer peripheral surface of the cylindrical roller is set in contact with the inner surfaces of the inner and outer concave grooves so that the rotational force is transmitted.

Further, in the case of carrying out such a telescopic rotation transmission shaft of the present invention, it is preferable that at least one of the inner shaft and the outer shaft is a ball as in the invention described in claim 4. The rigidity of the portion provided with the concave groove constituting the concave groove set provided with only the cylindrical groove is made smaller than the rigidity of the portion provided with the concave groove constituting the concave groove set provided with only the cylindrical roller.
In this case, for example, a part of the cylindrical outer shaft is made thin (thin) in the vicinity of the outer side concave groove constituting the concave groove set in which only the ball is provided, or in the vicinity thereof. A slit can be provided in the part in a state of penetrating the inner and outer peripheral surfaces. In addition, the inner shaft is formed in a cylindrical shape, and a part of the inner shaft formed in the cylindrical shape has a small thickness in the vicinity of the inner groove formed in the groove set in which only the ball is provided ( It is also possible to provide a slit in such a state that the inner wall and the outer circumferential surface penetrate each other.

In the case of implementing such a telescopic rotation transmission shaft of the present invention, preferably, the rigidity of the balls in the circumferential direction of the inner shaft and the outer shaft is set to the same circumference as in the invention described in claim 5. Reduce the rigidity of the cylindrical roller relative to the direction (ball rigidity << cylindrical roller rigidity). That is, when the rotational force is transmitted, the ball is compared with the cylindrical roller so that the inner and outer concave grooves and the cylindrical roller can be easily engaged with each other as the rotational force increases. Thus, it is more easily elastically deformed than based on the difference in shape.
In this case, for example, the material is changed between the ball and the cylindrical roller (the material of the ball is more easily elastically deformed than the material of the cylindrical roller), or the balls are hollow. In addition, a slit can be provided in the ball so as to penetrate both the inner and outer peripheral surfaces. In addition, by providing a recess (not penetrating) on the outer peripheral surface of this ball (whether it is hollow or solid) so as to be recessed radially inward from this outer peripheral surface, The surface (outer peripheral surface) can be easily elastically deformed.

Further, when the telescopic rotation transmission shaft of the present invention is implemented, preferably, as in the invention described in claim 6, the inner side and outer side concave grooves are arranged at equal intervals in the circumferential direction of the inner shaft and outer shaft. Provided at multiple locations. Preferably, as in the invention described in claim 7, a set of concave grooves provided with only cylindrical rollers is provided at a plurality of locations in the circumferential direction of the inner shaft and the outer shaft. In this case, it is also preferable to provide a set of concave grooves provided only with this cylindrical roller at a plurality of locations at equal intervals in the circumferential direction of the inner shaft and the outer shaft .

According to the telescopic rotation transmission shaft of the present invention configured as described above, it is inexpensive, and even when a large rotational force (torque) is transmitted, damage such as indentation can hardly occur ( It does not lead to a decrease in durability, and can be smoothly expanded and contracted in the axial direction). For this reason, transmitting a large rotational force (increasing the allowable load torque), performing smooth axial expansion / contraction without rattling, and reducing manufacturing costs can be arranged side by side.
That is, in the case of the present invention, since it is not necessary to provide an elastic member for applying an elastic force to the ball, it can be configured at a low cost. Further, since the rotational force can be transmitted not only through the balls but also through the cylindrical rollers, a large rotational force can be transmitted by that amount (the contact area can be increased by the cylindrical rollers). Can be larger). In addition, since the cylindrical rollers share such a large rotational force, it is possible to prevent an excessive increase in surface pressure at the contact portion between the ball and the concave groove, resulting in damage such as indentation. It can be difficult.

  In addition, in the case of the present invention, the surface of the ball is brought into contact in the vicinity of the groove bottom portion of the inner surface (inner surface) of each inner side and outer side concave groove, and the outer peripheral surface of the cylindrical roller is set to the inner side and outer side. Since the contact is made in the vicinity of the shoulder portion of the inner surface of each side groove, the transmission of the rotational force can be surely shared by the cylindrical roller as the rotational force increases. That is, at the contact portion between the surface of the ball and the inner surface of each of the inner and outer grooves, the contact angle increases, so the component force applied in the direction of receiving the rotational force is small, and this rotational force is It becomes difficult to be transmitted through the ball. For this reason, when the rotational force is applied to the contact portion between the surface of the ball and the inner surfaces of the inner and outer concave grooves, relative rotation between the inner shaft and the outer shaft tends to be permitted. On the other hand, the contact angle between the outer peripheral surface of the cylindrical roller and the inner surface of each of the inner and outer concave grooves is small, so that the rotational force can be easily received at the contact portion. For this reason, as the rotational force increases, the cylindrical roller can reliably share the transmission of the rotational force.

As described above, when a rotational force is applied at the contact portion between the surface of the ball and the inner surfaces of the inner and outer concave grooves, relative rotation between the inner shaft and the outer shaft tends to be permitted. Become. That is, when the rotational force is applied, with the relative rotation between the inner shaft and the outer shaft, the rotational force is not applied to the contact portion between the surface of the ball and the inner surfaces of the inner and outer concave grooves. It tends to be displaced (shifted) laterally (in the rotational direction) from the contact position in the unloaded state. For this reason, even if indentation based on contact with the surface of the ball is generated on the surface of each of the inner and outer concave grooves by applying a large rotational force, the position where the indentation is generated is The position is out of contact with the surface of the ball in an unloaded state where the rotational force is not applied. Therefore, regardless of the indentation (even if an indentation occurs), the relative displacement in the axial direction between the outer shaft and the inner shaft (expandable rotation transmission shaft) is performed in a no-load state in which the rotational force is not applied. Can be smoothly expanded and contracted.
Further, in the case of the present invention, since the felt which is an elastic piece for restricting the axial position of the cylindrical roller is provided, the end faces of the cylindrical rollers facing each other in the axial direction (or the end faces of the cylindrical rollers) And the generation of noise due to a collision between the end surface and the axially facing member can be prevented. In addition, since the felt is impregnated (held) with the lubricating oil, the lubricating oil can be supplied to the contact portion between the outer peripheral surface of the cylindrical roller and the inner surface of the inner and outer concave grooves. Rubbing (squeezing, stick sliding) can be made difficult to occur at the contact portion.

  Further, as in the invention described in claim 2, if the outer diameter of the ball is made larger than the outer diameter of the cylindrical roller, the axial relative displacement between the outer shaft and the inner shaft (extension / contraction of the telescopic rotation transmission shaft) ) Can be performed based on the rolling of the ball having a large outer diameter. For this reason, this relative displacement (extension / contraction operation) can be smoothly performed also from this surface. Further, by making the outer diameter of the ball larger than the outer diameter of the cylindrical roller in this way, in the state where the rotational force is small, only the above ball is based on the engagement (engagement) with the inner and outer concave grooves. When this rotational force is transmitted and the rotational force is large, the cylindrical roller can also be engaged (engaged) with the inner and outer concave grooves so that the rotational force can be transmitted. In this way, the outer diameter of the ball and the outer diameter of the cylindrical roller are regulated, and the transmission of the rotational force can be surely shared by the cylindrical roller, so that this surface can also be constructed at a low cost ( Manufacturing costs can be reduced).

Further, as in the invention described in claim 3, when the ball is provided with a tightening allowance for the inner and outer concave grooves, the inner shaft and the outer shaft are not required without an elastic member. Prevents rattling in the direction of rotation.
Further, as in the invention described in claim 4, at least one of the inner shaft and the outer shaft, the rigidity of the portion provided with the concave grooves constituting the concave groove set provided with only balls is reduced ( If it is easy to be elastically deformed), it is possible to easily engage (engage) the cylindrical roller and the inner and outer concave grooves as the rotational force increases. For this reason, when the rotational force is transmitted, a large rotational force can be surely shared by the cylindrical roller, and damage such as indentation can be less likely to occur. In addition, when the ball has a tightening allowance for the inner and outer concave grooves, the degree of freedom (allowance) for the tightening allowance can be increased (insensitive to the tightening allowance).

  That is, even if the tightening allowance is large (whether or not it is conscious), the rigidity of the portion provided with the inner and outer concave grooves, which constitutes the concave groove set provided with only the balls. Is less likely to be elastically deformed, so that indentations can be less likely to be formed on the inner surfaces of the inner and outer concave grooves in contact with the balls. In addition, since the indentation is less likely to occur even when the tightening margin is increased in this way, it is not necessary to maintain a high processing accuracy of the inner and outer concave grooves and the ball (accurate dimensional errors are allowed. ), It can be configured at a low price (the manufacturing cost can be reduced). Moreover, the preload (resistance) based on the tightening allowance can be prevented from becoming excessively large, the inner shaft and the outer shaft can be prevented from rattling in the rotational direction, and the axial relative displacement (extension and contraction of the telescopic rotation transmission shaft) can be prevented. Highly compatible with smoothing. Moreover, it is easy to ensure a necessary preload (resistance) over a long period of time regardless of the wear of the inner and outer grooves.

  Further, as in the invention described in claim 5, even when the rigidity of the balls in the circumferential direction of the inner shaft and the outer shaft is made smaller than the rigidity of the cylindrical rollers, The inner and outer concave grooves and the cylindrical rollers can be easily engaged (engaged). For this reason, when the rotational force is transmitted, a large rotational force can be surely shared by the cylindrical roller, and damage such as indentation can be less likely to occur. At the same time, by appropriately adjusting the rigidity of the ball and the cylindrical roller, it is possible to easily adjust the timing at which the cylindrical roller starts to share the rotational force when the rotational force is transmitted (restricted to a desired timing). Easy to do). The adjustment of the timing at which such cylindrical rollers begin to share the rotational force is performed by adjusting the rigidity of the inner shaft and the outer shaft as a whole, as in the invention described in claim 4 above. The same can be done by appropriately adjusting the rigidity of the inner and outer groove portions of the shaft.

FIG. 25 shows four examples of the relationship between the rotation angle between the inner shaft and the outer shaft and the torsional torque applied between the inner shaft and the outer shaft. In FIG. 25, points P _{1 to} P ₄ indicate the outer peripheral surface of each cylindrical roller and each concave portion from the state where the rotational force is transmitted based on the engagement between the surface of each ball and the inner surface of each concave groove. Inflection points that change to a state in which the inner surface of the groove abuts and the rotational force is transmitted are shown. As described above, the rigidity of each ball, the tightening allowance of each ball, the rigidity of the inner shaft and the outer shaft, the number of concave grooves on the inner side and the outer side, the cross-sectional shape, the radius of curvature, each ball and each cylindrical roller By appropriately adjusting the difference in the outer diameter and the like, it is possible to obtain a desired relationship between the torsional torque and the rotation angle (arbitrary setting of response during steering wheel operation, kickback input, etc.). Note that when the ball rigidity is reduced as described above, the change in the inclination before and after the inflection point (for example, point P ₄ ) increases as the rigidity decreases. For this reason, simply as it is, there is a possibility that a change in torque twisting, for example, from the inflection point P ₄ as shown by the two-dot-dash line, in such a case, resulting in abnormal noise or feel a sense of discomfort (stopper feeling) there is a possibility. Therefore, for example, by appropriately adjusting the rigidity of each cylindrical roller, the cross-sectional shape of each concave groove in contact with each cylindrical roller, the radius of curvature, the contact angle between the outer peripheral surface of each cylindrical roller and the inner surface of each concave groove, etc. For example, it is preferable that the inflection point is shifted to P ₄ ′ so that smooth torque transmission can be performed. Also, by appropriately adjusting the rigidity and tightening allowance of each ball, the cross-sectional shape of each concave groove that comes into contact with each ball, the radius of curvature, the contact angle between the surface of each ball and the inner surface of each concave groove, etc. The part indicated by Q in FIG. 25 can be made to be a smooth curve toward the inflection points P _{1 to} P ₄ .

  Further, as in the invention described in claim 6, when the inner side and outer side concave grooves are provided at a plurality of positions at equal intervals in the circumferential direction of the inner shaft and outer shaft, the concave grooves provided only with balls are provided. The inner side and outer side concave grooves constituting the set, and the inner side and outer side concave grooves constituting the concave groove set provided only with the cylindrical rollers are each easily elastically deformed. Damage such as indentation can be made less likely to occur. Further, when forming the inner side and outer side concave grooves in the inner shaft and outer shaft, the inner shaft and outer shaft can be easily formed as desired. That is, for example, when a concave groove is formed in the shaft together with the formation of the shaft based on plastic processing, a molding load can be applied evenly in the circumferential direction of the shaft, and the bending direction and the cross-sectional shape of the shaft are, for example, It can be difficult to deform in a distorted direction. For this reason, it is possible to achieve both high smoothness of axial relative displacement between the outer shaft and the inner shaft (extension and contraction of the telescopic rotation transmission shaft) and prevention of rattling in the circumferential direction.

Further, as in the invention described in claim 7, when the concave groove set provided only with the cylindrical roller is provided at a plurality of positions in the circumferential direction of the inner shaft and the outer shaft, the amount of the cylindrical roller is increased. Rotational force can be transmitted (allowable load torque can be increased).

[ Example of Embodiment ]
1 to 3 show an example of an embodiment of the present invention corresponding to claims 1 to 3. In addition, this example has shown about the structure in the case of implementing the expansion-contraction type rotational transmission shaft of this invention as the steering shaft 20. FIG. However, the present invention is not limited to such a steering shaft 20, for example, the intermediate shaft 5 shown in FIG. 22 described above and the like that require both functions of transmission of torque (torque) and expansion and contraction in the axial direction. Can be implemented as a shaft. In any case, the steering shaft 20 of this example is extruded into a metal material such as carbon steel and the outer shaft 21 formed by subjecting the metal material such as carbon steel to extrusion processing or cutting. Each of the inner shafts 22 formed by forging or cutting is made of a metal material such as carbon steel, bearing steel, and stainless steel, or a non-metallic material such as a synthetic resin or a high-performance resin. A plurality of transmission pieces 23a and 23b are provided. Out of these, the outer shaft 21 has a cylindrical shape, and is (four) outer side grooves in a state of being recessed radially outward from the inner peripheral surface at four positions in the circumferential direction of the inner peripheral surface. 24, 24 are provided in the axial direction.

  The inner shaft 22 has a cylindrical or columnar shape and is positioned radially inward from the outer peripheral surface at a position aligned with the outer-side concave grooves 24, 24 at four positions in the circumferential direction of the outer peripheral surface. In the recessed state, (four) inner side grooves 25 and 25a are provided in the axial direction. The transmission pieces 23a and 23b are provided between the outer side concave grooves 24 and 24 and the inner side concave grooves 25 and 25a, respectively. The transmission pieces 23a and 23b are interposed between the transmission pieces 23a and 23b. By combining the outer shaft 21 and the inner shaft 22, the rotational force can be transmitted and the axial relative displacement can be performed between the outer shaft 21 and the inner shaft 22. In the case of this example, some of the transmission pieces 23a and 23b are balls 26 and 26, and the remaining portions are cylindrical rollers 27 and 27. More specifically, a part (two sets) of the (four sets) concave groove groups each constituted by the outer side concave grooves 24, 24 and the inner side concave grooves 25, 25a which are paired with each other. As shown in FIG. 2, only a plurality of (seven) balls 26, 26 are provided in the groove set (the leftmost groove set and the rightmost groove set in FIG. 1) (the cylindrical roller 27 is provided). Not) At the same time, the remaining (two sets) of groove sets (the uppermost groove set and the lowermost groove set in FIG. 1) are divided into a plurality of (three) cylinders as shown in FIG. Only the rollers 27 and 27 are provided (the ball 26 is not provided).

  In the case of this example, the two sets of concave grooves provided only with the balls 26 and 26 are arranged at positions opposite to the radial direction (180 degrees opposite side), that is, at equal intervals of 180 degrees in the circumferential direction. The two groove sets each provided with the cylindrical rollers 27 and 27 are also provided in the arranged state, and are also arranged at the positions opposite to the radial direction (180 degrees opposite side), that is, equally spaced by 180 degrees with respect to the circumferential direction. Are provided in a state of being arranged in each. Thus, it is possible to arrange the balls 26, 26 and the cylindrical rollers at the same time in the circumferential direction (180 ° equal interval for 2 sets, 120 ° equal interval for 3 sets, etc.) when transmitting rotational force. It is more preferable from the viewpoint that 27 and 27 can be evenly stretched.

  Further, in the case of this example, the inner side (inner side surface) of each of the outer side and inner side concave grooves 24, 25 constituting the concave groove group provided with only the balls 26, 26 of the respective concave groove groups, and each A contact groove (contact portion, engagement portion, meshing portion) (in a neutral state where no rotational force is applied) with the surface of the balls 26, 26 is configured as a concave groove set in which only cylindrical rollers 27, 27 are provided. Contact portion between the inner surface (inner surface) of each of the outer and inner concave grooves 24, 25a and the outer peripheral surface of each cylindrical roller 27, 27 (in a state where the outer peripheral surface and the inner surface are in contact with each other based on rotational force) The outer side and inner side concave grooves 24 and 25 are positioned on the bottom side of the grooves on the outer side and the inner side with respect to the contact part, the engaging part, and the meshing part. In other words, the surfaces of the balls 26 and 26 are brought into contact with the groove bottoms of the inner surfaces of the outer and inner concave grooves 24 and 25, and the outer peripheral surfaces of the cylindrical rollers 27 and 27 are Contact is made in the vicinity of the shoulder portion of the inner surfaces of the outer and inner concave grooves 24 and 25a.

In the case of this example in which the contact position is regulated in this way, the contact angle θ ₁ between the surface of each of the balls 26 and 26 and the inner surface of each of the outer and inner concave grooves 24 and 25 (the ball in the neutral state) The angle θ ₁ ) between the virtual planes in contact with both end portions of the contact portion between the surface of each of the concave grooves 24 and 25 and the outer surfaces of the cylindrical rollers 27 and 27 and the outer and inner Contact angles θ ₂ , θ ₃ with the inner surfaces of the respective concave grooves 24, 25 a (when it is assumed that the outer peripheral surface of the cylindrical rollers 27, 27 and both inner surfaces of the concave grooves 24, 25 a are in contact with each other in a neutral state , The angle θ ₂ , θ ₃ ) formed by the virtual planes in contact with the contact portion becomes larger. More specifically, the contact angle θ ₁ between the surface of each of the balls 26, 26 and the inner surface of each of the outer and inner concave grooves 24, 25 increases (becomes an obtuse angle), and the cylindrical rollers 27 , 27 and contact angles θ ₂ and θ ₃ between the outer and inner concave grooves 24 and 25a are reduced (become acute angles). By adopting such a configuration, in the case of this example, as the rotational force (torque) increases, the cylindrical rollers 27, 27 are connected to the outer and inner concave grooves 24, 25a. It is engaged (engaged) so that this rotational force can be transmitted.

In short, in the case of this example, the surface of each of the balls 26 and 26 is the inner surface of each of the outer and inner grooves 24 and 25 constituting the groove set provided with only the balls 26 and 26. in the manner in contact with the groove bottom portion near the (by increasing the contact angle theta _1), the rolling surface and the outer side of the balls 26, 26, the contact position between the inner surface of the inner side each groove 24, 25 A small rotational force facilitates the lateral displacement from the bottom of each of the concave grooves 24 and 25. For this reason, for example, when the cross-sectional shape of each of the outer and inner concave grooves 24 and 25 is a single circular arc, the radius of curvature is made larger than the radius of the balls 26 and 26 and the contact The position should be close to the groove bottom. Further, when the cross-sectional shape of each of the outer and inner concave grooves 24 and 25 is a Gothic arch shape, the contact angle is increased so that the contact position is near the groove bottom. The cross-sectional shape is preferably a single arc from the surface where the contact position is in the vicinity of the groove bottom as described above. It is preferable to make it easy to displace. On the other hand, the surface of each cylindrical roller 27, 27 is the shoulder of the inner surface of each of the outer and inner side concave grooves 24, 25a constituting the concave groove set provided with only the cylindrical rollers 27, 27. The contact portion between the outer peripheral surface of each of the cylindrical rollers 27 and 27 and the inner surface of each of the outer and inner concave grooves 24 and 25a so as to make contact in the vicinity of the portion (reducing contact angles θ ₂ and θ ₃ ) This makes it easier to support the rotational force.

  In the case of this example, the elastic member 16 (see FIGS. 23 to 24) as shown in FIGS. 23 to 24 is not provided in each groove set provided with only the balls 26 and 26. That is, the pressing force (preload) is not applied by the elastic member 16 to the balls 26 and 26 (and the cylindrical rollers 27 and 27) of the respective groove sets {the respective balls 26, 26 (and each cylindrical roller 27, 27) is pressed against the inner surface of at least one of the outer grooves 24, 24 and the inner grooves 25, 25. Not done}. In the case of this example, instead of providing such an elastic member 16, only the balls 26, 26 out of the balls 26, 26 and the cylindrical rollers 27, 27 are provided on the outer side, inner side. A tightening allowance (including a clearance 0 and a tightening allowance 0) is provided for each of the side concave grooves 24 and 25.

  That is, in a state in which the outer shaft 21 and the inner shaft 22 are combined and in a neutral position where no rotational force is applied between the outer shaft 21 and the inner shaft 22 (the concave portions where only the balls 26 and 26 are provided). Each ball 26, 26 with respect to the diameter of an imaginary circle (inscribed circle between the concave grooves 24, 25 facing each other) formed by the inner surfaces of the outer side and inner side concave grooves 24, 25). The outer diameter in the free state is the same or increased (very little, for example, about 1/100 to 1/1000 of the outer diameter of the ball 26). On the other hand, each of the cylindrical rollers 27, 27 does not have an allowance for the outer side and inner side concave grooves 24, 25a (which constitute a concave groove set in which only the cylindrical rollers 27, 27 are provided). That is, in the case of this example, the outer diameter of each of the cylindrical rollers 27, 27 is smaller than the outer diameter of the balls 26, 26 (the outer diameter of the balls 26> the outer diameter of the cylindrical rollers 27). . In addition, the diameter of the imaginary circle formed by the inner surfaces of the outer and inner concave grooves 24 and 25a at the neutral position (which constitutes the concave groove set provided only with the cylindrical rollers 27 and 27), The outer diameter of each of the cylindrical rollers 27 and 27 is made very small (for example, about 1/100 to 1/1000 of the outer diameter of the cylindrical roller 27) to provide a gap with respect to each of the concave grooves 24 and 25a. Yes.

FIG. 6 exaggeratedly shows a state in which the cylindrical rollers 27, 27 are provided with gaps with respect to the outer and inner concave grooves 24a, 25b. In FIG. 6, the cross-sectional shape of each of the outer and inner concave grooves 24 a and 25 b is a Gothic arch shape. As described above, by reducing the contact angles θ ₂ and θ ₃ between the outer circumferential surface of each cylindrical roller 27 and 27 and the inner surfaces of the outer and inner concave grooves 24a and 25b, a rotational force is applied. The surface of each cylindrical roller 27, 27 is brought into contact with the vicinity of the shoulder portion of the inner surface of each of the outer and inner concave grooves 24a, 25b constituting the concave groove set provided with only the cylindrical rollers 27, 27. The load capacity is secured. Further, when the cross-sectional shape is changed to the above-described Gothic arch shape, for example, a single arc shape, the radius of curvature is set to be equal to the outer diameter of each of the cylindrical rollers 27, 27, and the load capacity Make it easier to secure. In any case, the cylindrical rollers 27, 27 are provided with a gap with respect to the outer and inner concave grooves 24a, 25b (24, 25a).

  By adopting the above-described configuration (the outer diameter of the ball 26> the outer diameter of the cylindrical roller 27), the outer diameter can be reduced with a small rotational force transmitted between the outer shaft 21 and the inner shaft 22. Only the balls 26, 26 having a large diameter transmit this rotational force based on the engagement (engagement per local point) with the outer and inner concave grooves 24, 25. On the other hand, in a state where the rotational force is large, each ball 26, 26 and the inner side and outer side concave grooves 24, 25 engaged with the balls 26, 26 are elastically deformed {each ball 26, 26 and the portion where the surface of each ball 26, 26 abuts (the portion of the inner surface of the concave groove 24, 25 which is the mating surface abuts the surface of each ball 26, 26) is elastically deformed (local part) By elastic deformation), the cylindrical rollers 27, 27 having a small outer diameter are also engaged with (engaged with) the outer and inner concave grooves 24, 25a (24a, 25b), and the rotational force. To communicate.

  In this example, in order to transmit such rotational force, in the case of this example, the tightening allowance given to the balls 26, 26, the outer diameters of the balls 26, 26, The relationship between the outer diameters of the cylindrical rollers 27 and 27, in other words, the outer diameters of the balls 26 and 26 and the cylindrical rollers 27 and 27, and the outer and inner concave grooves 24, 25, and 25a (24a, 25b) of the imaginary circle formed by the inner surface (inner surface) and the radius of curvature (or inclination, etc.) of the cross-sectional shape of each of the outer and inner concave grooves 24, 25, 25a (24a, 25b) The relationship is regulated as follows. First, the tightening allowance (the difference between the outer diameter of each ball 26, 26 and the diameter of the imaginary circle) of each of the balls 26, 26 is determined according to each of the balls 26, 26 and the outer and inner concave grooves 24, 25. Indentation does not occur in the outer and inner concave grooves 24, 25 within the range in which the elastic deformation occurs, that is, even if it occurs, the durability is not reduced and the axial expansion and contraction can be smoothly performed. Set within the range. At the same time, the outer diameters of the cylindrical rollers 27, 27 are set within a range in which the balls 26, 26 and the outer and inner concave grooves 24, 25 are elastically deformed when the rotational force is transmitted. That is, each of the above-mentioned each is within a range in which no indentation is generated in each of the outer side and inner side concave grooves 24 and 25 (even if it is generated, the durability is not reduced and the axial expansion and contraction can be smoothly performed). The outer peripheral surfaces of the cylindrical rollers 27 and 27 are set to contact the inner surfaces (inner surfaces) of the outer and inner concave grooves 24 and 25a (24a and 25b) so that the rotational force is transmitted.

According to the telescopic rotation transmission shaft (steering shaft 20) of the present example configured as described above, it is inexpensive, and even when a large rotational force is transmitted, damage such as indentation can hardly occur (as it has occurred). However, the durability does not decrease and the axial expansion and contraction can be smoothly performed). For this reason, transmitting a large rotational force (increasing the allowable load torque), performing smooth axial expansion / contraction without rattling, and reducing manufacturing costs can be arranged side by side.
That is, in the case of this example, parts production, parts management, and assembly work are performed as long as there is no need to provide an elastic member (for example, the elastic member 16 in FIGS. 23 to 24) for applying an elastic force to the balls 26, 26. Both can be simplified and constructed at low cost. At the same time, since the rotational force can be transmitted not only through the balls 26 and 26 but also through the cylindrical rollers 27 and 27, the cylindrical rollers 27 and 27 having a large contact area are recessed. As much as it abuts against the inner surface of the grooves 24, 25a (24a, 25b)}, a large rotational force can be transmitted (allowable load torque can be increased). In addition, since the cylindrical rollers 27 and 27 share such a large rotational force, the surface pressure of the contact portion between the balls 26 and 26 and the grooves 24 and 25 is excessively large. It is also possible to prevent the occurrence of damage such as indentation.

In addition, in the case of this example, the surfaces of the balls 26 and 26 are brought into contact with each other in the vicinity of the groove bottom portions of the inner surfaces of the outer and inner concave grooves 24 and 25, and the cylindrical rollers 27 and 27. Since the outer peripheral surface is brought into contact in the vicinity of the shoulder portion of the inner surfaces of the outer and inner concave grooves 24 and 25a (24a and 25b), the transmission of the rotational force is transmitted as the rotational force increases. 27, 27 can be shared with certainty. That is, the surface and the outer side of the balls 26, 26, at the contact portion between the inner surface of the inner side each groove 24 and 25, since the contact angle theta ₁ is greater, applied in a direction for receiving the rotational force min The force is small, and this rotational force is difficult to be transmitted through these balls 26 and 26. For this reason, when the rotational force is applied at the contact portion between the surface of each ball 26, 26 and the inner surface of each of the outer and inner concave grooves 24, 25, the inner shaft 22 and the outer shaft 21 are rotated relative to each other. Tends to be acceptable. On the other hand, the contact angles θ ₂ and θ ₃ are at contact portions between the outer peripheral surfaces of the cylindrical rollers 27 and 27 and the inner surfaces of the outer and inner concave grooves 24 and 25a (24a and 25b). Since it becomes small, it can make it easy to receive the said rotational force in this contact part. For this reason, with the increase in the rotational force, the cylindrical rollers 27 and 27 can reliably share the transmission of the rotational force.

  In the case of this example, the outer diameters of the balls 26, 26 are larger than the outer diameters of the cylindrical rollers 27, 27, so the axial direction of the outer shaft 21 and the inner shaft 22 is increased. Relative displacement (extension and contraction of the telescopic rotation transmission shaft) can be performed based on the rolling of the balls 26 and 26 having a large outer diameter. For this reason, this relative displacement (extension / contraction operation) can be smoothly performed also from this surface. Moreover, in the case of this example, by making the outer diameters of the balls 26 and 26 larger than the outer diameters of the cylindrical rollers 27 and 27 in this way, the balls 26 and 26 are in a state where the rotational force is small. Only the outer side and inner side concave grooves 24, 25 are engaged (engaged) to transmit this rotational force, and in a state where this rotational force is large, each of the cylindrical rollers 27, 27 is also connected to the outer side, The rotational force is transmitted by engaging (meshing) with the inner side concave grooves 24 and 25a (24a and 25b). In this way, by restricting the outer diameter of each ball 26, 26 and the outer diameter of each cylindrical roller 27, 27, it is possible to reliably share the transmission of rotational force by each of these cylindrical rollers 27, 27. Also from this aspect, it can be constructed at a low price (the manufacturing cost can be reduced).

  Further, in the case of this example, since the balls 26, 26 are provided with a tightening margin for the outer side and inner side concave grooves 24, 25, the elastic member (for example, the elastic member of FIGS. 23 to 24). Even if 16) is not provided, the outer shaft 21 and the inner shaft 22 can be prevented from rattling in the rotational direction. If such rattling can be tolerated (for example, if it does not cause a problem during running even if a certain amount of rattling), allow a tightening margin within a range in which this rattling can be tolerated. (For example, the outer diameter of each ball 26, 26 is made smaller than the diameter of a virtual circle formed by the inner surfaces of the outer and inner concave grooves 24, 25) You can also do things. Further, in the case where no allowance is provided (a gap is provided), the position of the contact point between the inner surface of each of the outer and inner concave grooves 24 and 25 and the surface of each of the balls 26 and 26 However, since it becomes easy to displace according to the rotational force, even if an indentation is generated, the relative displacement in the axial direction between the outer shaft 21 and the inner shaft 22 (the steering shaft 20 is (Extension and contraction) can be performed smoothly.

FIG. 4 shows the change in the contact point position between the inner surfaces of the outer and inner concave grooves 24 and 25 and the surfaces of the balls 26 and 26 in the case where each ball 26 and 26 has a tightening allowance. Show. In FIGS. 4A and 4B, the cross-sectional shapes of the outer and inner concave grooves 24 and 25 are single arcs. FIG. 4A shows a no-load state (a state where no rotational force is applied), and FIG. 4B shows a state where a rotational force is applied. In addition, the points α shown in FIGS. 4 (A) and 4 (B) are respectively the inner surfaces (inner surfaces) of the outer and inner concave grooves 24 and 25 in the unloaded and neutral state. The contact point position with the surface of each ball | bowl 26 and 26 is shown. Then, as shown in FIG. 4B, when the rotational force is applied, each ball 26 and the outer side and inner side concave grooves 24, 25 are based on the elastic deformation (recess grooves 24, 25). The contact point position from point α to point β, the radius of curvature R of the inner surfaces of the outer and inner concave grooves 24 and 25 and the radius of each ball 26 (= D / 2) Is displaced by a distance {δ ₁ , δ ₂ } in FIG. In addition, it is preferable that this displacement is performed while the contact point positions are in continuous contact.

  In any case (in the case of a structure with or without a tightening allowance), by applying a large rotational force, the inner surfaces of the outer and inner concave grooves 24 and 25 and the balls 26 described above are applied. Even if an indentation is generated at the contact portion with the surface of the surface, the position of the contact point is displaced as described above. Since the position β where the indentation is generated is shifted from the contact point position α when there is no load, the axial relative displacement (extension and contraction of the steering shaft 20) between the outer shaft 21 and the inner shaft 22 that is performed when there is no load. It can be performed smoothly regardless of the presence of the indentation. It should be noted that both the outer side and inner side recesses are provided when a large rotational force is applied, both in the case of a structure having such a tightening allowance and in the structure having no tightening allowance. Since the cylindrical rollers 27 and 27 having a large contact area with the grooves 24 and 25a share the rotational force, the indentation is hardly generated.

  FIG. 5 shows a structure in which the outer side and inner side concave grooves 24a and 25b are formed in a Gothic arch shape (which constitutes a concave groove set in which only the balls 26 are provided). In the case of such a Gothic arch-like structure, as shown in FIG. 5A, the contact point position α is the central portion (groove) of the outer side and inner side concave grooves 24a and 25b even when there is no load. Deviations from the deepest part). In such a structure, the torsional rigidity can be increased, but the displacement amount (deviation amount) of the contact point position is hardly increased (the deviation amount is small) in a state where a large rotational force is applied. However, as will be described later, by reducing the thickness of the cylindrical outer shaft 21 and the inner shaft 22 (for example, by providing a thin portion), the outer shaft 21 and the inner shaft 22, and the outer side, If the inner side concave grooves 24a and 25b are easily elastically deformed, the contact point position α can be easily shifted to β. In addition, by making it easy to be elastically deformed in this way, it is possible to transmit this rotational force with each cylindrical roller 27, 27 from a state where a small rotational force is applied. It can be difficult to occur.

  In any case, in the case of this example, the surface of each of the balls 26, 26 is in contact with the vicinity of the groove bottom portion of the inner surfaces of the outer and inner concave grooves 24, 25. With respect to, when a rotational force is applied, relative rotation between the inner shaft 22 and the outer shaft 21 tends to be permitted. That is, when the rotational force is applied, as the inner shaft 22 and the outer shaft 21 rotate relative to each other, the surfaces of the balls 26 and 26 contact the inner surfaces of the outer and inner concave grooves 24 and 25. The portion tends to be displaced (shifted) laterally (rotational direction) from the contact position in the no-load state where the rotational force is not applied. For this reason, even if indentation based on contact with the surface of each ball 26, 26 occurs on the surface of each of the outer side and inner side concave grooves 24, 25 by applying a large rotational force, The position where the indentation is generated is a position deviated from the contact position with the surface of each of the balls 26 and 26 in an unloaded state where the rotational force is not applied. For this reason, the axial relative displacement between the outer shaft 21 and the inner shaft 22 (expandable rotation transmission) is performed in an unloaded state where the rotational force is not applied regardless of the indentation (even if an indentation occurs). The shaft can be expanded and contracted smoothly.

  In the case of this example, as shown in FIG. 2, each ball 26, 26 is held by a cage 28, thereby positioning each ball 26, 26 (restricting play). 26 and 26 prevent the outer side and inner side concave grooves 24 and 25 from rattling in the axial direction. Further, when such a cage 28 is provided, the balls 26 and 26 can be easily assembled between the outer and inner concave grooves 24 and 25. In the case of this example, as shown in FIG. 3, the cylindrical rollers 27 and 27 are held in the axial direction by a pair of elastic pieces 29 and 29. That is, among these cylindrical rollers 27 and 27, the cylindrical rollers 27 and 27 positioned on both ends with respect to the axial direction of the outer and inner concave grooves 24 and 25, and the outer and inner concave grooves 24, respectively. The elastic pieces 29 and 29 are respectively provided in a state of being elastically compressed in the axial direction between the retaining rings 30 and 30 provided at the end portions of 25a and 25a.

The elastic pieces 29 and 29 provide the cylindrical rollers 27 and 27 with an elastic force in a direction approaching each other, thereby preventing the generation of noise due to the collision between the end faces of the cylindrical rollers 27 and 27. doing. Note that felt is used as the elastic pieces 29 and 29 . Further, by impregnating the felt as such elastic pieces 29 and 29 with lubricating oil, the outer peripheral surface of each of the cylindrical rollers 29 and 29 and the inner surfaces (inner surfaces) of the outer and inner concave grooves 24 and 25a. It is easy to supply lubricating oil to the contact part . In addition, as shown in FIG. 7, it is also preferable to provide the elastic pieces 29, 29 between the end faces of the cylindrical rollers 27, 27 facing each other. Even when such a configuration is adopted , since the felt impregnated with the lubricating oil is used as the elastic pieces 29, 29 , the lubricating oil can be more easily supplied.

Further, as each of the cylindrical rollers 27, 27, for example, a cylindrical member 17 (see FIGS. 23 to 24) as shown in FIGS. 23 to 24 described above, that is, a cylindrical roller long in the axial direction can be used. However, it is preferable to provide a large number of cylindrical rollers 27, 27 that are short in the axial direction from the viewpoint of preventing excessive surface pressure and rubbing (squeezing, stick sliding) associated with the local area. Moreover, such localized per the accompanying excessive surface pressure and rubbing (prying, stick slip) in terms of prevention of, by using a felt impregnated with such lubricating oil described above, the cylindrical rollers 27 and 27 Lubricating oil is supplied to the contact portion between the outer peripheral surface and the inner surface (inner surface) of each of the outer and inner concave grooves 24 and 25a .

[ First example of reference example of the present invention ]
FIG. 8 shows a first example of a reference example relating to the present invention . In the case of this reference example , in the outer shaft 21a, the thickness of the portion in the vicinity of the outer side concave grooves 24, 24 constituting the concave groove set provided with only the balls 26, 26 is also set to the outer side concave grooves. The thickness is made smaller than the thickness of the portion removed from the grooves 24, 24. For this reason, in the case of this reference example, a pair of each outer side concave groove 24, 24 is paired with the peripheral portion of the outer side concave groove 24, 24 sandwiched between the outer peripheral surface of the outer shaft 21a. Each flat part 31, 31 is provided. And by comprising in this way, the rigidity of the part which provided the said outer side ditch | groove 24,24 which comprises the ditch | groove set which provided only the said balls 26,26 among the said outer shaft 21a (cylindrical) The outer side concave grooves 24, 24 constituting the concave groove set provided only with the rollers 27, 27 are made smaller (easily elastically deformed).

In the case of this reference example as described above, as the rotational force increases, the cylindrical rollers 27 and 27 can be easily engaged (engaged) with the outer and inner concave grooves 24 and 25a. Therefore, when the rotational force (torque) is transmitted, a large rotational force can be surely shared by the cylindrical rollers 27 and 27, and damage such as indentation can be made less likely to occur. Moreover, when the balls 26, 26 are provided with a tightening allowance for the outer and inner concave grooves 24, 25, the degree of freedom (allowance) for the tightening allowance can be increased (insensitive to the tightening allowance). Can). That is, even if the tightening allowance is large (whether or not it is conscious), the portions provided with the outer-side concave grooves 24, 24 are less rigid (easily elastically deformed) It is possible to make it difficult to generate indentations in the outer and inner concave grooves 24 and 25 that are in contact with the balls 26 and 26. In addition, even if the tightening allowance is increased, it is difficult to generate indentation. Therefore, the processing accuracy of the outer and inner recesses 24 and 25 and the balls 26 and 26 must be maintained at a high level. Finished (allows dimensional errors), and can be configured at a lower cost (reducing manufacturing costs). In addition, the preload (resistance) based on the tightening allowance can be prevented from becoming excessively large, and the inner shaft 22 and the outer shaft 21a can be prevented from rattling in the rotational direction and the axial relative displacement (extension and contraction of the telescopic rotation transmission shaft). ) Can be achieved at a high level. Further, it is possible to ensure a necessary preload (resistance) over a long period of time regardless of the wear of the outer and inner concave grooves 24 and 25. In the case of this reference example , the tightening allowance of the balls 26, 26 can be set to, for example, about 1/5 to 1/1000 of the outer diameter of the balls 26, 26 (reversely, each cylinder The gap between the rollers 27 and 27 can be made, for example, about 1/5 to 1/1000 of the outer diameter of each of the cylindrical rollers 27 and 27).

In the case of this reference example, a pair of flat portions 31, 31 are provided at two positions in the circumferential direction of the outer peripheral surface of the outer shaft 21a. The torsional rigidity of the outer shaft 21a is provided. If it is desired to ensure, it may be provided at one position in the circumferential direction. In addition, a large rotational force (torque) is not applied to the vicinity of the outer side concave grooves 24, 24 constituting the concave groove group provided with only the balls 26, 26 (the large rotational force is not applied to the cylindrical rollers 27, 27). Therefore, instead of the flat portions 31 and 31 as described above, for example, as shown in FIG. 9, a part of the outer shaft 21a is formed with a groove set provided with only the balls 26 and 26. The slit grooves 32, 32 which are long in the axial direction of the outer shaft 21a are provided in the vicinity of the portion where the outer groove 24 is provided (a portion slightly deviated in the circumferential direction from the outer groove 24). It can also provide in the state penetrated from the outer peripheral surface to the inner peripheral surface.

Further, in the case of this reference example , a part of the outer shaft 21a (the vicinity of the outer side concave grooves 24, 24 constituting the concave groove set provided only with the balls 26, 26) is made thin (outer shaft). 21a makes the inner shaft 22 cylindrical, and a part of the inner shaft 22 (a concave groove set provided only with balls 26, 26) is formed on the inner side concave groove 21a. 25, the vicinity of 25) can be made thin (the inner shaft 22 can be easily elastically deformed). Of course, a part of the members of both the inner shaft 22 and the outer shaft 21a (the portions near the outer and inner concave grooves 24, 25 constituting the concave groove set provided only with the balls 26, 26) are made thin. You can also do it.
The configuration and operation of the other parts are the same as in the example of the embodiment of the present invention described above . Accordingly, if a felt impregnated with lubricating oil is provided in the present reference example, as in this example of the embodiment of the present invention, the embodiment of the present invention is obtained , and therefore redundant illustrations and descriptions are omitted. To do.

[ Second Example of Reference Example of the Present Invention ]
FIG. 10 shows a second example of the reference example related to the present invention . In the case of this reference example , in the inner shaft 22a, the vicinity of the inner side concave grooves 25a, 25a constituting the concave groove set provided only with the balls 26, 26 is easily elastically deformed (the rigidity is increased). Small). For this reason, in the case of this reference example, the thickness of the ball receiving portions 33, 33 provided in a state of sandwiching the balls 26, 26 in the circumferential direction (thickness in the circumferential direction of the inner shaft 22a) The thickness of the cylindrical roller receiving portions 34, 34 provided with the cylindrical rollers 27, 27 sandwiched in the circumferential direction (thickness in the circumferential direction of the inner shaft 22a) is reduced.

In order to reduce the weight of the inner shaft 22a, it is possible to provide the thinning portions 35 and 35 as shown by a two-dot chain line in FIG. 10 on the outer peripheral surface of the inner shaft 22a. In the case of this reference example, the thickness of the ball receiving portions 33, 33 of the inner shaft 22a is smaller than that of the cylindrical roller receiving portions 34, 34. And a cylindrical roller receiving portion, and the thickness of the ball receiving portion can be made smaller (easily elastically deformed and less rigid) than the thickness of the cylindrical roller receiving portion. Of course, the thickness of the ball receiving portions of both the inner shaft and the outer shaft can be made smaller than the thickness of the cylindrical roller receiving portion.
The configuration and operation of other parts are the same as those of the above-described example of the embodiment and the first example of the reference example . Therefore, the structure of the present embodiment, similarly to the example embodiment of the present invention described above, by providing a felt impregnated with lubricating oil, from the embodiment of the present invention, shown overlapping and Description is omitted.

[ Third example of reference example of the present invention ]
11 to 12 show a third example of the reference example related to the present invention . In the case of this reference example , by providing a flat portion 36 at one position in the circumferential direction of the outer peripheral surface of the outer shaft 21b, a portion of the outer shaft 21b is made thinner than the other portions. In the case of this reference example , the flat portion 36 is not provided over the entire axial direction of the outer shaft 21b, but provided only in a part in the axial direction, and a portion that cannot be thinned (for example, if rigidity is not secured). The thickness of parts that must not be covered) is secured. Further, in the case of this reference example , the outer side concave portion is provided by providing the flat portion 36 in the vicinity of the outer side concave grooves 24, 24 constituting the concave groove set provided with only the balls 26, 26. The vicinity of the grooves 24, 24 is easily elastically deformed (the rigidity is reduced). In this way, by making it easy to elastically deform the vicinity of the outer side concave grooves 24, 24, the necessary tightening margin (preload based on the tightening margin) is ensured regardless of variations in processing accuracy (rattle). The steering shaft 20 can be smoothly expanded and contracted while preventing sticking. At the same time, when a large rotational force (torque) is applied, this large torque can be surely shared by the cylindrical rollers 27 and 27.

In the case of this reference example , the outer side and inner side concave grooves 24 and 25 are provided at a plurality of positions at equal intervals in the circumferential direction of the outer shaft 21 b and the inner shaft 22. Also, together with this, two of the groove sets constituted by the outer and inner groove grooves 24 and 25 that are paired with each other are either the ball 26 that is the transmission piece 23a or 23b and the cylindrical roller 27. Is not provided. That is, in the case of the present reference example , only the balls 26 and 26 are provided in a part (2 sets) of the above-mentioned concave groove sets, and also in a part (2 sets) of the remaining parts (4 sets). Only cylindrical rollers 27, 27 are provided. However, the cylindrical roller 27 can be provided in a groove set in which neither the ball 26 nor the cylindrical roller 27 is provided, for example, in order to increase the allowable load torque. In any case, in the case of this reference example , the outer side and inner side concave grooves 24 and 25 are provided at a plurality of circumferentially equidistant positions on the outer shaft 21b and the inner shaft 22, so that each ball 26 , 26, each of the outer side and inner side concave grooves 24, 25 constituting the concave groove set, and each of the outer side, inner side concave grooves 24 constituting the concave groove group provided only with the cylindrical rollers 27, 27. , 25 are easily elastically deformed uniformly, and damage such as indentation can be made less likely to occur in each of the concave grooves 24, 25. Further, when the outer and inner concave grooves 24 and 25 are formed in the outer shaft 21b and the inner shaft 22, the outer shaft 21b and the inner shaft 22 can be easily formed as desired. That is, for example, when forming the concave grooves 24 and 25 in the shafts 21b and 22 together with the formation of the shafts 21b and 22 based on plastic processing, it is possible to apply a molding load evenly in the circumferential direction of the shafts 21b and 22. The shafts 21b and 22 can be hardly deformed, for example, in a bending direction or a direction in which a cross-sectional shape is distorted. For this reason, it is possible to achieve both high smoothness of axial relative displacement (extension / contraction of the telescopic rotation transmission shaft) between the outer shaft 21b and the inner shaft 22 and prevention of rattling in the circumferential direction.

In the case of the present reference example , the thin portion of the outer shaft 21b having a reduced thickness is formed by forming the single flat portion 36 as described above. For this reason, like the structure of the first example (FIG. 8) of the reference example described above, a pair of flat portions 31, 31 and a curved surface portion 37 (FIG. 8) existing between the flat portions 31, 31. Compared with the case of providing a reference), it is possible to facilitate the work of forming (cutting) the thin portion.
In addition, as shown in FIG. 13, each ball | bowl 26 can also be exposed from the flat part 36a. Further, as shown in FIGS. 14 to 15, the thin portion can be formed by providing a pair of flat portions 36 b and 36 c.
The configuration and operation of the other parts are the same as those of the above-described example of the embodiment and the first and second examples of the reference example . Therefore, the structure of the present embodiment, similarly to the example embodiment of the present invention described above, by providing a felt impregnated with lubricating oil, from the embodiment of the present invention, shown overlapping and Description is omitted.

[ Fourth example of a reference example related to the present invention ]
16-17 has shown the 4th example of the reference example regarding this invention . In the case of this reference example , among the outer peripheral surfaces of the outer shaft 21c, these outer peripheral surfaces are aligned with the outer side concave grooves 24, 24 constituting the concave groove set provided with only the balls 26, 26. A slit groove 32a is provided in a state of penetrating the bottom of the outer side concave grooves 24, 24. And the rise of the surface pressure of the contact part of the surface of each said balls 26 and 26 and the inner surface of each concave groove 24 and 25 is suppressed.
The structure and operation of the other parts are the same as in the third example of the reference example described above . Therefore, the structure of the present embodiment, similarly to the example embodiment of the present invention described above, by providing a felt impregnated with lubricating oil, from the embodiment of the present invention, shown overlapping and Description is omitted.

[ Fifth Example of Reference Example Related to the Present Invention ]
18 to 19 show a fifth example of the reference example related to the present invention . In the case of this reference example , the rigidity of the ball 26a in the circumferential direction of the inner shaft 22 and the outer shaft 21 (for example, see FIGS. 1 to 3) is compared with the rigidity of the cylindrical roller 27 (for example, see FIGS. 1 and 3). (The rigidity of the ball 26a << the rigidity of the cylindrical roller 27). That is, at the time of transmission of the rotational force, as the rotational force increases, the outer side and inner side concave grooves 24 and 25 (see, for example, FIGS. 1 to 3) and the cylindrical roller 27 are easily engaged. Compared with this cylindrical roller 27, 26a is more easily elastically deformed than based on the difference in shape. For this reason, in the case of this reference example, the ball 26a is made hollow, and a slit 38 is provided in the ball 26a so as to penetrate both the inner and outer peripheral surfaces. Such a slit 38 can have a curved shape (wavy shape) as shown in FIG. 18, and can also have a concave-convex shape as shown in FIG. 19A, for example, or as shown in FIG. It can also be a straight line.

In the case of such a reference example, the ball 26a is provided with a margin for tightening the concave grooves 24, 25 on the outer side and the inner side because the ball 26a is more easily elastically deformed (small rigidity). Even when the steering shaft 20 (for example, see FIGS. 1 to 3) is expanded or contracted, the ball 26a can be easily rolled regardless of the tightening allowance. Further, since the ball 26a can be easily elastically deformed, the difference between the outer diameter of the ball 26a and the outer diameter of the cylindrical roller 27 can be increased. In addition, the outer shaft 21 and the inner shaft 22 provided with the balls 26a, the cylindrical rollers 27, the outer side and inner side concave grooves 24 and 25, and the outer side and inner side concave grooves 24 and 25, respectively. There is no need to ensure a high degree of shape accuracy and dimensional accuracy. Further, it is not necessary to make the outer shaft 21 and the inner shaft 22 easily elastically deformed {for example, the thickness is adjusted, the flat portions 31, 36, 36a to 36c (FIGS. 8, 11 to 15) or the slit groove 32. 32a (FIGS. 9, 16, and 17) need not be provided}, and accordingly, the processing of the outer shaft 21 and the inner shaft 22 can be facilitated.

In the case of this reference example , the ball 26a is made hollow and the slit 38 is provided. For example, the ball 26a can be a solid body. In this way, when the ball 26a is a solid body, for example, a desired elasticity can be obtained by a material constituting the ball 26a. For example, as a material constituting this ball 26a, Young's modulus is different from general bearing steel (Young's modulus is lower than bearing steel), stainless steel, cast iron, aluminum alloy, copper, brass (brass), Synthetic resin can be used. Alternatively, the cylindrical roller 27 can be made of ceramic with a high Young's modulus, and the ball 26a can be made of bearing steel. Further, by providing a concave portion on the surface of the ball 26a so as to be recessed from the surface, it is possible to reduce the crushing rigidity in the minute surface range of the ball 26a and obtain desired elasticity. . Further, the surface of the ball 26a may be subjected to a surface treatment such as hard chrome plating so as to obtain a desired elasticity. In any case, by adjusting the elasticity of the ball 26a (adjusting the elastic coefficient of the ball 26a, the elastic region, etc.) and adjusting the outer diameter of each ball 26a and each cylindrical roller 27, FIG. As shown, the initial torsional rigidity, the timing at which the cylindrical rollers 27 and 27 start to share the rotational force, and the like can be adjusted as desired. For this reason, it is possible to easily perform optimum setting in accordance with the steering characteristics required for the vehicle.
The configuration and operation of other parts are the same as those of the above-described example of the embodiment and the first to fourth examples of the reference example . Therefore, the structure of the present embodiment, similarly to the example embodiment of the present invention described above, by providing a felt impregnated with lubricating oil, from the embodiment of the present invention, shown overlapping and Description is omitted.

[ Sixth Reference Example for the Present Invention ]
FIG. 21 shows a sixth example of the reference example relating to the present invention . In the case of this reference example , six sets of concave grooves each constituted by the outer side concave grooves 24 and 24 and the inner side concave grooves 25 and 25 that are paired with each other are formed as the diameters of the outer shaft 21d and the inner shaft 22b. Three sets each are provided at opposite positions (180 degrees opposite). That is, in the case of the present reference example , three in each of the outer shafts 21d are recessed radially outward from the inner peripheral surface at positions opposite to the inner peripheral surface of the outer shaft 21d (total of six ) Of the outer side concave grooves 24, 24. Further, in a state where the outer circumferential surface of the inner shaft 22b is opposite to the outer circumferential surface and opposed to the outer grooved grooves 24, 24, the inner shaft 22b is recessed radially inward from the outer circumferential surface. The inner side concave grooves 25, 25 are provided by three (six in total). Of the concave groove groups provided at three positions opposite to each other in the radial direction, only the cylindrical rollers 27 and 27 are provided in the central concave groove group, and the concave groove groups on both sides of the central concave groove group are provided. Only balls 26 and 26 are provided, respectively. Further, in the case of the present embodiment, a portion of the thickness t _1, the other portion of the cylindrical of the outer shaft 21d, particularly, the thickness of the portion deviated from the respective outer side grooves 24, 24 t It is smaller than ₂ . More specifically, among the outer shaft 21d, the thickness t ₁ of the portion near the outer side groove 24, 24 constituting the groove sets provided with only the balls 26, 26, also these outer side The thickness is smaller than the thickness t ₂ of the portion outside the concave grooves 24, 24.

In the case of this reference example , since six sets of groove sets are provided at the positions on the opposite side in the radial direction (180 degree opposite side), the outer side grooves 24 and 24 are provided. The outer shaft 21d can be easily elastically deformed. That is, the outer shaft 21d can be easily elastically deformed into an ellipse having a major axis in the direction in which the outer side concave grooves 24, 24 are provided. For this reason, the deformation resistance with respect to the tightening allowance of each of the balls 26 and 26 can be made insensitive (small), and damage such as indentation can be hardly caused regardless of the tightening allowance. Further, in the case of this reference example , the outer side concave grooves 24, 24 constituting the concave groove set provided only with the balls 26, 26, which are thin portions of the outer shaft 21d, are provided. The provided part is easily elastically deformed, and it is possible to make it difficult to generate indentations in these outer side concave grooves 24, 24. At the same time, as the rotational force increases, the outer and inner concave grooves 24 and 25 and the cylindrical rollers 27 and 27 can be easily engaged (engaged easily). For this reason, when the rotational force is transmitted, a large torque can be more reliably assigned to the cylindrical rollers 27 and 27, and from this surface, damage such as indentation can be hardly caused. Moreover, by adjusting the wall thicknesses t ₁ and t ₂ , it is possible to easily adjust the timing at which the cylindrical rollers 27 and 27 start to share the rotational force (torque) when transmitting the rotational force (desired) Can be easily controlled at the timing of).

Moreover, in the case of this reference example , compared with the structure of one example of embodiment mentioned above and the 1st-4th example of a reference example, the outer side (which comprises the groove set which provided the transmission pieces 23a and 23b) Since the number of inner grooves 24 and 25 is large, the force shared by the balls 26 and 26 and the cylindrical rollers 27 and 27 when transmitting rotational force can be reduced, and damage such as indentations can be achieved. Can be made more difficult to occur. In other words, it is possible to transmit a larger rotational force (increase the allowable load torque) by reducing the force shared in this way. Further, the total number of balls 26 and 26 and cylindrical rollers 27 and 27 to be incorporated is reduced by the larger number of outer and inner grooves 24 and 25 (which constitute a groove set provided with transmission pieces 23a and 23b). Without any problem, the overall length in the axial direction of the balls 26 and 26 and the cylindrical rollers 27 and 27 incorporated between the outer and inner concave grooves 24 and 25 to be paired can be shortened. In this way, the overall length in the axial direction of each of the balls 26 and 26 and the cylindrical rollers 27 and 27 existing between the outer and inner concave grooves 24 and 25 to be paired is shortened. As much as possible, the axial length of the portion of each of the concave grooves 24, 25 that is out of the balls 26, 26 and the cylindrical rollers 27, 27 is secured, and the expansion / contraction stroke of the steering shaft 20 is secured. Easy to do.
The configuration and operation of the other parts are the same as those of the above-described example of the embodiment and the first to fifth examples of the reference example . Therefore, if the felt impregnated with lubricating oil is provided in the structure of this reference example as in the above-described example of the embodiment of the present invention, the embodiment of the present invention is obtained. The description is omitted.

[Points to note when implementing the present invention]
The present invention is not limited to the structures of the embodiments and reference examples described above, and can be implemented with various structures such as appropriately combining the structures of these embodiments and reference examples . Various changes can be made to the shape, structure, and material of each component.

  The telescopic rotation transmission shaft of the present invention can be applied to the intermediate shaft 5 among the structural members of the automobile steering apparatus having the electric power steering apparatus shown in FIG. . However, not only the intermediate shaft 5 but also the steering shaft 3 (20) disposed inside the steering column 9 can be implemented. Furthermore, the present invention is not limited to the shaft constituting the automobile steering device, but can be implemented as a rotation transmission shaft constituting various rotary machine devices such as machine tools and playground equipment.

The figure equivalent to the II cross section of FIG. 3 which shows an example of embodiment of this invention. FIG. 2 is a view corresponding to the roll cross section of FIG. 1. FIG. 2 is a view corresponding to the cross section of FIG. FIGS. 2A and 2B are diagrams corresponding to two parts of FIG. 1 in which the cross-sectional shape of the groove is a single circular arc. FIG. 1A shows a state where no rotational force (torque) is applied (no load), and FIG. The state where (torque) is applied is shown. FIG. 2 is a view corresponding to two parts of FIG. 1 in which the cross-sectional shape of the concave groove is a Gothic arch, where (A) shows a state where no rotational force (torque) is applied (no load), and (B) shows a rotational force ( The state where torque is applied is shown. FIG. 2 is a view corresponding to the portion E in FIG. 1, in which the cross-sectional shape of the groove is a Gothic arch. The figure similar to FIG. 3 which shows the other example of the ditch | groove set which provided only the cylindrical roller. The figure similar to FIG. 1 which shows the 1st example of the reference example regarding this invention . The figure seen from the arrow direction of FIG. 8 which shows another example. The figure similar to FIG. 1 which shows the 2nd example of the reference example regarding this invention . The fragmentary perspective view which shows the 3rd example . FIG. 12 is a cross-sectional view of the tote of FIG. The figure similar to FIG. 12 which shows the 1st example of another example. The figure similar to FIG. 11 which shows the 2nd example of another example. FIG. 15 is a cross-sectional view of the teaching of FIG. The fragmentary perspective view which shows the 4th example of the reference example regarding this invention . FIG. 17 is a cross-sectional view of the relay of FIG. The front view which takes out only a ball and shows the 5th example of the reference example regarding this invention . The figure which shows another two examples of the slit formed in a ball | bowl. The diagram which shows the relationship between a twist angle and rotational force (torque). The figure similar to FIG. 1 which shows the 6th example of the reference example regarding this invention . The partial vertical side view which shows an example of the steering device for motor vehicles. The figure similar to FIG. 1 which shows an example of the expansion-contraction type rotational transmission shaft known conventionally. The exploded perspective view. The diagram for demonstrating the relationship between a twist angle and rotational force (torque).

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering gear unit 3, 3a Steering shaft 4a, 4b Universal joint 5 Intermediate shaft 6 Input shaft 7 Tie rod 8 Electric motor 9 Steering column 10, 10a Outer shaft 11, 11a Inner shaft 12 Outer column 13 Inner column 14 Steel ball DESCRIPTION OF SYMBOLS 15 Cage 16 Elastic member 17 Cylindrical member 18 Outer side concave groove 19 Inner side concave groove 20 Steering shaft 21, 21a, 21b, 21c, 21d Outer shaft 22, 22a, 22b Inner shaft 23a, 23b Transmission piece 24, 24a Outer side Concave groove 25, 25a, 25b Inner side concave groove 26, 26a Ball 27 Cylindrical roller 28 Cage 29 Elastic piece 30 Retaining ring 31 Flat part 32, 32a Slit groove 33 Ball receiving part 3 Cylindrical roller receiving portion 35 cutouts 36, 36a, 36b, 36c flat portion 37 curved portion 38 slit

Claims (7)

The inner shaft is provided with inner side grooves recessed radially inward at a plurality of circumferential positions on the outer circumferential surface, and the inner side grooves are aligned with each other at a plurality of circumferential positions on the inner circumferential surface. Between the outer shaft and the inner side groove and each outer side groove. A telescopic rotation transmission shaft comprising a plurality of transmission pieces provided on the outer shaft, wherein the outer shaft and the inner shaft are combined with each other so as to enable transmission of rotational force between them and relative displacement in the axial direction. ,
A part of each of the transmission pieces is a ball, and the remaining part is a cylindrical roller, and a part of each groove set constituted by the inner groove and the outer groove that are paired with each other. Only the above-mentioned ball is provided in the groove set of the same, and only the cylindrical roller is provided in the remaining groove set, and further, a contact portion between the surface of the ball and the inner surface of each groove on the inner side and outer side, The cylindrical roller is positioned closer to the groove bottom side of each inner and outer groove than the contact portion between the outer peripheral surface of the cylindrical roller and the inner surface of each inner and outer groove. The roller engages with the inner and outer concave grooves so that this rotational force can be transmitted .
Felt, which is an elastic piece for restricting the axial position of the cylindrical roller, is provided at both ends of the remaining groove set provided with only the cylindrical roller with respect to the axial direction of the inner shaft and the outer shaft. A telescopic rotation transmission shaft characterized by impregnating a felt with lubricating oil . The outer diameter of the ball is larger than the outer diameter of the cylindrical roller.
The telescopic rotation transmission shaft according to claim 1. Only the ball of the ball and cylindrical roller has a tightening allowance for the inner and outer grooves.
The telescopic rotation transmission shaft according to any one of claims 1 and 2. Of at least one of the inner shaft and the outer shaft, the rigidity of the portion provided with the concave groove constituting the concave groove set provided only with the ball is configured, and the concave groove set provided with only the cylindrical roller is also configured. Smaller than the rigidity of the part where the concave groove
The telescopic rotation transmission shaft according to any one of claims 1 to 3. The rigidity of the ball in the circumferential direction of the inner shaft and the outer shaft is also smaller than the rigidity of the cylindrical roller in the circumferential direction.
The telescopic rotation transmission shaft according to any one of claims 1 to 4. Inner side and outer side recessed grooves are provided at a plurality of locations at equal intervals in the circumferential direction of the inner shaft and outer shaft.
The telescopic rotation transmission shaft according to any one of claims 1 to 5. A set of concave grooves provided only with cylindrical rollers was provided at a plurality of locations in the circumferential direction of the inner shaft and outer shaft.
The telescopic rotation transmission shaft according to any one of claims 1 to 6.

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