JP2007321789A - Assembly method of machine parts - Google Patents

Abstract

A method for assembling a machine part with improved work efficiency is provided.
A clearance upper limit value CU1 determined by a stopper pin angle maximum value A1 and a clearance lower limit value CL1 determined by a maximum sliding resistance R1 are determined. Based on the shaft spline diameter OPD1, the tube spline diameter BBD, and the clearance allowable range (CU1-CL1), the tolerance of the outer diameter of the cylindrical body is determined. An average torsional rigidity TA is obtained, and a lower limit PL1 of the preload amount determined by the average torsional rigidity TA and the torsional rigidity standard is determined. From the maximum sliding resistance R1 according to the sliding resistance standard, the upper limit value PU1 of the preload amount determined by the maximum sliding resistance R1 is determined. From the shaft spline diameter OPD2 and the tube spline diameter BBD, the clearance between both spline grooves and the spherical body is obtained, and the outer diameter of the spherical body is determined based on the clearance and the tolerance of the preload amount (PU1-PL1). Define tolerances for
[Selection] Figure 10

Description

  The present invention relates to a method for assembling a machine part, and more particularly, to a method for assembling a machine part mainly for expanding and contracting torque transmission having a spline groove, a key part, and a preload structure.

For example, a vehicular steering mechanism is provided with a telescopic spline shaft, which functions to absorb axial displacement generated when the vehicle travels and not transmit the displacement or vibration on the steering wheel. ing. Further, the spline shaft functions so as to allow the steering wheel when the driver moves the shaft in the axial direction in order to obtain an optimal position for driving the vehicle (see Patent Document 1).
JP 2005-313691 A

  By the way, the conventional spline shaft assembling method is intended to satisfy the conflicting criteria of reducing the amount of axial rotation direction rudder and sliding resistance, which are problems in practice, in order to satisfy the conflicting standards. A ball with a dimension that gives an appropriate preload from the measurement result by measuring the amount of play in the axial circumference when a measurement reference ball with a slightly smaller dimension is interposed from the space formed by both spline grooves on the shaft. After selecting the diameter, the ball used for the measurement is removed, and the ball with the dimensions determined by experiment etc. is assembled from the measurement result, so that the play amount and the sliding resistance can be adjusted to the desired amount. I have been.

  However, even if the sliding resistance is set within a predetermined range, the amount of axial backlash may be inappropriate. Furthermore, although a spline shaft that suppresses the amount of play by incorporating a preload mechanism has been developed, in the case of such a spline shaft, it is necessary to satisfy the relationship between sliding resistance, spline shaft torsional rigidity, and backlash. For this reason, in order to obtain desired mechanical characteristics, there has been a problem that the work efficiency is poor because the ball diameter selection work and the sliding resistance, the torsional rigidity of the spline shaft, and the backlash amount measurement are often repeated a plurality of times.

  The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide a method for assembling a machine part with improved work efficiency.

The mechanical component assembling method of the present invention includes a spline shaft having a spline groove on the inner periphery, a spline male shaft having a spline groove on the outer periphery, a first key component disposed in both the first group of spline grooves, In a method for assembling a machine part having a second key part and a preload structure arranged in both spline grooves of the second group,
Measuring the spline groove dimension of the spline male shaft and the spline groove dimension of the spline female shaft;
Measurement results of both spline groove dimensions, clearance between the first group of both spline grooves and the first key parts obtained in advance through experiments, etc., axial sliding resistance during expansion and contraction, and axial stopper pins Selecting a dimension of the first key part based on a relationship with an angle;
Measurement result of both spline groove dimensions, and preload structure when the dimension of the second key part is changed in the gap between the second group of both spline grooves and the second key part obtained in advance through experiments or the like Selecting the dimension of the second key part based on the relationship between the amount of preload applied to the shaft, the torsional rigidity in the axial circumferential direction, and the sliding resistance in the axial direction during expansion and contraction;
A step of incorporating the first key part and the second key part having the selected dimensions and the preload structure between the spline male shaft and the spline female shaft.

  In the present invention, the measurement results of the dimensions of both spline grooves, the gap between the first group of both spline grooves and the first key part, obtained in advance through experiments, etc., the sliding resistance in the axial direction during expansion and contraction, and the shaft circumference Since there is a step of selecting the dimension of the first key part based on the relationship with the direction of the stopper pin angle in the direction, the stopper pin angle and the sliding resistance can be easily set to desired values. Further, when the dimension of the second key part is changed in the gap between the second key part and the measurement result of both the spline groove dimensions and the second group of both spline grooves obtained in advance through experiments or the like. Since there is a step of selecting the dimension of the second key component based on the relationship between the amount of preload given to the preload structure, the torsional rigidity in the axial direction and the sliding resistance in the axial direction during expansion and contraction, this is desirable. The torsional rigidity in the axial direction and the sliding resistance in the axial direction during expansion and contraction can be easily set to desired values. As described above, according to this assembling method, it becomes easy to select key parts for configuring desired mechanical characteristics, and an efficient assembling work can be performed.

  Here, the “stopper pin angle” means an angle at which torque is transmitted mainly by a cylindrical body, and in the torsional rigidity measurement of the mechanical parts assembled by the assembling method of the present invention, the clockwise rotation direction or the specified torque The rotation angle obtained when torque is applied in the left rotation direction and the torque measurement result are defined as a range of two intersection angles between the inclination near the specified torque and the horizontal axis of the graph (see FIG. 8). In general, in a region below the stopper pin angle, torque transmission is performed via a preload elastic body such as a spherical body and a leaf spring. “Torsional rigidity” is a line showing the relationship between the rotational angle and additional torque obtained when a right torque direction or left rotation direction is applied to a machine part assembled by the assembling method of the present invention up to a specified torque. In the figure, the rotation angle is defined by an average value of inclinations near 0 (the torsional rigidity of the first key part + the torsional rigidity of the second key part) / 2 (see FIG. 9).

  In the present invention, the measurement results of the dimensions of both spline grooves, the gap between the first group of both spline grooves and the first key part, obtained in advance through experiments, etc., the sliding resistance in the axial direction during expansion and contraction, and the shaft circumference Since there is a step of selecting the dimension of the first key part based on the relationship with the direction of the stopper pin angle in the direction, the stopper pin angle and the sliding resistance can be easily set to desired values. Further, when the dimension of the second key part is changed in the gap between the second key part and the measurement result of both the spline groove dimensions and the second group of both spline grooves obtained in advance through experiments or the like. Since there is a step of selecting the dimension of the second key part based on the relationship between the preload amount applied to the preload structure, the torsional rigidity in the axial direction and the sliding resistance in the axial direction during expansion and contraction, The torsional rigidity in the axial direction and the axial sliding resistance in the axial direction during expansion and contraction can be easily set to desired values. As described above, according to this assembling method, it becomes easy to select key parts for configuring desired mechanical characteristics, and an efficient assembling work can be performed.

  It is preferable that the mechanical component is a telescopic shaft used in a steering device.

  Hereinafter, a steering apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view of a steering mechanism portion of an automobile to which a vehicle steering telescopic shaft according to an embodiment of the present invention is applied.

  In FIG. 1, a steering shaft upper part 3 is attached to a vehicle body VB via an upper bracket 1 and a lower bracket 2. The steering shaft upper part 3 includes a steering column 3A and a steering shaft 3B rotatably held by the steering column 3A. A steering wheel 5 is attached to the upper end of the steering shaft 3B. A steering shaft lower portion 7 is connected to the lower end of the steering shaft 3B via a universal joint 6.

  A pinion shaft 9 is connected to the steering shaft lower portion 7 via a steering shaft joint 8, and the pinion shaft 9 is further connected to a steering rack shaft 12. The steering rack shaft 12 is supported by a steering rack support member 13 fixed to the vehicle body VB ′ via an elastic body 11.

  Here, the steering shaft upper portion 3 and the steering shaft lower portion 7 use the vehicle steering telescopic shaft (hereinafter referred to as the telescopic shaft) according to the embodiment of the present invention. The lower portion 7 of the steering shaft is a fitting of a spline male shaft (hereinafter abbreviated as a male shaft) and a spline female shaft (hereinafter abbreviated as a female shaft). Such a steering shaft lower portion 7 is required to have a performance that absorbs the displacement in the axial direction generated when the vehicle travels and does not transmit the displacement or vibration on the steering wheel 5. In such a performance, the vehicle body has a sub-frame structure, and the vehicle body VB to which the steering shaft upper part 3 is fixed and the vehicle body VB ′ to which the steering rack support member 13 is fixed are separated. This is particularly required in the case of a structure in which the rack support member 13 is fastened and fixed to the vehicle body VB ′ via an elastic body 11 such as rubber.

  Further, when the steering shaft joint 8 is fastened to the pinion shaft 9 at the time of assembly or maintenance, the operator needs to expand and contract because the telescopic shaft is once contracted and then fitted and fastened to the pinion shaft 9. There is a case. Furthermore, the steering shaft upper part 3 at the upper part of the steering mechanism is also one in which a male shaft and a female shaft are fitted. The steering shaft upper part 3 is optimal for a driver to drive a vehicle. In order to obtain the position, the function of moving the position of the steering wheel 5 in the axial direction and adjusting the position is required, so the function of expanding and contracting in the axial direction is required. In all the cases described above, it is possible to reduce the rattling noise of the fitting portion on the telescopic shaft, to reduce the rattling on the steering wheel 5, and to reduce the sliding resistance when sliding in the axial direction. Required.

  FIG. 2 is a longitudinal sectional view of the telescopic shaft for vehicle steering according to the embodiment of the present invention. 3 is a cross-sectional view of the configuration of FIG. 2 taken along the line III-III and viewed in the direction of the arrow. FIG. 4 is a perspective view of a leaf spring that is an elastic body.

  As shown in FIG. 2, the telescopic shaft 110 for vehicle steering is composed of a male shaft 101 and a female shaft 102 that are non-rotatable and slidably fitted in the axial direction. As shown in FIG. 3, three axial grooves (spline grooves) 103 that are equally arranged at intervals of 120 degrees (phase) in the circumferential direction are formed on the outer peripheral surface of the male shaft 101. Correspondingly, three axial grooves (spline grooves) 115 that are equally arranged at intervals of 120 degrees in the circumferential direction (phase) are formed to extend on the inner peripheral surface of the female shaft 102.

  A plurality of rigid spherical bodies 107 (second key components) that roll between the spline grooves 103 of the male shaft 101 and the spline grooves 105 of the female shaft 102 when the shafts 101 and 102 move relative to each other in the axial direction. Rolling elements or balls) are movably interposed. The spline groove 105 of the female shaft 102 has a substantially arc-shaped cross section or a Gothic arch shape. The spline grooves 103 and 105 constitute a second group of spline grooves.

  The spline groove 103 of the male shaft 101 has a substantially trapezoidal cross section, and has a pair of inclined planar side surfaces 103a and a bottom surface 103b formed flat between the pair of planar side surfaces 103a. A leaf spring 109 for contacting and preloading the spherical body 107 is interposed between the spline groove 103 of the male shaft 101 and the spherical body 107.

  As shown in FIG. 4, the leaf spring 109 constituting the preload structure has a substantially arc-shaped spherical body side contact portion 109 a that contacts the spherical body 107 at two points, and a predetermined axially circumferential direction with respect to the spherical body side contact portion 109 a. The groove surface side contact portion 109b, which is bent at a distance and can contact the planar side surface 103a of the spline groove 103 of the male shaft 101, and the spherical body side contact portion 109a and the groove surface side contact portion 109b are mutually connected. And an urging portion 109c bent so as to be elastically urged in a direction away from each other, and a flat bottom surface 109d facing the flat bottom surface 103b of the spline groove 103.

  As shown in FIG. 3, the urging portion 109c has a substantially U shape and is bent in a substantially arc shape, and the sphere-side contact portion 109a and the groove are formed by the urging portion 109c having the bent shape. The surface side contact portions 109b can be elastically biased so as to be separated from each other.

  A small gap (Δ1) is set between the urging portion 109 c or the groove surface side contact portion 109 b and the planar side surface 103 a of the spline groove 103.

  Further, when the leaf spring 109 is bent, the tip of the groove surface side contact portion 109b is bent in the arrow (G) direction so as not to contact the planar side surface 103a of the spline groove 103 as shown in FIG. Yes.

  The largest outer shape portion of the R shape of the bent portion (the biasing portion 109 c or the groove surface side contact portion 109 b) is set so as to be closest to the planar side surface 103 a of the spline groove 103.

  This is to make the thickness of the bent portion (the urging portion 109c or the groove surface side contact portion 109b) of the leaf spring 109 constant at any location. This is because if the tip of the bent portion (the biasing portion 109c or the groove surface side contact portion 109b) hits unevenly at each location, the torsional rigidity of the preload portion is not stable.

  As shown in FIGS. 3 and 4, in this embodiment, the spherical body side contact portion 109 a that contacts the spherical body 107 is formed in a substantially arc shape larger than the radius of the spherical body 107. Thereby, a contact surface pressure with the spherical body 107 can be lowered rather than a planar shape.

  As shown in FIG. 3, three spline grooves 104 that are equally arranged at intervals of 120 degrees (phase) in the circumferential direction are formed to extend on the outer peripheral surface of the male shaft 101. Correspondingly, three spline grooves 106 that are equally arranged at intervals of 120 degrees (phase) in the circumferential direction are formed to extend on the inner peripheral surface of the female shaft 102.

  A plurality of rigid cylindrical bodies 108 (first key) that slide between the spline grooves 104 of the male shaft 101 and the spline grooves 106 of the female shaft 102 when the shafts 101 and 102 move relative to each other in the axial direction. A sliding body or needle roller, which is a part, is interposed with a minute gap. The spline grooves 104 and 106 are a first group of spline grooves and have a substantially arc-shaped cross section or a Gothic arch shape.

  A minute gap (Δ2) is set between the cylindrical body 108 and the spline groove 106 of the female shaft 102. However, the spline groove 104 of the male shaft 101, the cylindrical body 108, and the spline groove 106 of the female shaft 102 may always be in contact with each other in the axial direction.

  In FIG. 2, a small diameter portion 101 a is formed at the end of the male shaft 101. The small-diameter portion 101a is provided with a stopper plate 111 that restricts the movement of the cylindrical body 8 in the axial direction. The stopper plate 111 includes an axial preload elastic body 112 (ie, a disc spring) and a pair of flat plates 113 and 113 (ie, plain washers) that sandwich the axial preload elastic body 112.

  In the present embodiment, the stopper plate 111 is fitted to the small diameter portion 101a in the order of the flat plate 113, the axial preload elastic body 112, and the flat plate 113, and is firmly fixed to the small diameter portion 101a by caulking. Thereby, the stopper plate 111 is fixed in the axial direction. The fixing method of the stopper plate 111 is not limited to caulking, but may be a retaining ring, a screwing means, a push nut, or the like. Further, the stopper plate 111 is configured so that the flat plate 113 is brought into contact with the cylindrical body 108 and can be appropriately preloaded by the axial preloading elastic body 112 so as not to move the cylindrical body 108 in the axial direction.

  Further, in the present embodiment, the six spline grooves 105 and 106 of the female shaft 102 are coaxially connected to the six spline grooves 103 and 104 on the outer peripheral surface of the male shaft 101 in the axial direction via gaps in the radial direction. Six substantially arc-shaped protrusions 115 formed in the above are fitted.

  Therefore, when the spherical body 107 and the cylindrical body 108 are dropped or broken from the male shaft 101 for some reason, the projection 115 of the male shaft 101 is fitted in the spline grooves 105 and 106 of the female shaft 102, Thereby, the male shaft 101 and the female shaft 102 can transmit torque, and can play the role of a fail-safe function.

  At this time, since a gap is provided between the spline grooves 105 and 106 and the protrusion 115, the driver can feel rattling in the steering wheel 5, and malfunction of the steering system or the like can occur. Can be sensed.

  Further, since the protrusion 115 of the male shaft 101 is coaxial with the spherical body 107 and the cylindrical body 108 in the axial direction, it also serves as a stopper for restricting the movement of the spherical body 107 and the cylindrical body 108 in the axial direction. The possibility of the body 107 and the cylindrical body 108 being detached can be reduced, and the fail-safe function can be further improved.

  Further, since the protruding portion 115 of the male shaft 101 is coaxial with the spherical body 107 and the cylindrical body 108 in the axial direction, the radial dimension of the male shaft 101 and the female shaft 102 can be reduced to achieve compactness. it can.

  Further, a lubricant may be applied between the spline groove 103 of the male shaft 101, the spline groove 105 of the female shaft 102, the leaf spring 109, and the spherical body 107. A lubricant may also be applied between the spline groove 104 of the male shaft 101, the cylindrical body 108, and the spline groove 106 of the female shaft 102.

  In the telescopic shaft configured as described above, the spherical body 107 is interposed between the male shaft 101 and the female shaft 102, and the spherical body 107 is preloaded to the extent that the female shaft 102 is not rattled by the leaf spring 109. Therefore, rattling between the male shaft 101 and the female shaft 102 can be reliably prevented, and when the male shaft 101 and the female shaft 102 move relative to each other in the axial direction, there is no stability. It is possible to slide with the sliding load.

  Next, a method for assembling the telescopic shaft according to the present embodiment will be described with reference to the drawings. FIG. 5 is a flowchart showing each step of the telescopic shaft assembling method according to the present embodiment. FIG. 6 is a schematic sectional view showing tube spline inner diameter (BBD) measurement. FIG. 7 is a schematic cross-sectional view showing shaft spline outer diameter (OPD) measurement. FIG. 8 is a diagram showing the Stover pin angle obtained in advance through experiments or the like. FIG. 9 is a diagram showing the torsional rigidity obtained in advance through experiments or the like. FIG. 10 is a diagram for explaining the dimension selection of the spherical body 107, and shows the relationship between the stopper pin angle and the sliding resistance with respect to the gap between the spline groove and the cylindrical body. FIG. 11 is a diagram for explaining the dimension selection of the cylindrical body 108, and shows the relationship between the preload amount of the preload structure (elastic body) provided by the spline groove and the spherical body, torsional rigidity, and sliding resistance. . Note that the outer diameters of the pins P1, P2, and P3 used for measurement are determined based on the design values of the tube and the shaft spline.

  First, in step S101 in FIG. 5, the spline groove dimension of the male shaft 101 and the spline groove dimension of the female shaft 102 are measured. More specifically, as shown in FIG. 6, when the small-diameter cylindrical pin P1 is brought into contact with the first group of spline grooves 104 of the male shaft 101, the diameter of the inscribed circle C1 is changed to the shaft spline. The diameter OPD1. Further, the large-diameter cylindrical pin 2 whose outer periphery is partially planar is brought into contact with the spline groove 103, and the diameter of the inscribed circle C2 is set as the shaft spline diameter OPD2. Further, as shown in FIG. 7, when the cylindrical pin P3 is brought into contact with the spline grooves 105 and 106 of the female shaft 102, the diameter of the circumscribed circle C3 is set as a tube spline diameter BBD. BBD, OPD1, and OPD2 are the dimensions of the spline grooves of the tube and the shaft, respectively.

  Subsequently, in step S102, the measurement result of both the spline grooves dimensions, the gap between the first group of both spline grooves 104, 106 and the cylindrical body 108 obtained in advance through experiments, etc., and the sliding in the axial direction during expansion and contraction. The dimensions of the cylindrical body 108 are selected based on the relationship between the resistance and the stopper pin angle in the axial direction. That is, if the gap between the spline grooves 104 and 106 and the cylindrical body 108 is too small, the sliding resistance increases and smooth torque transmission cannot be performed. On the other hand, if the gap between the spline grooves 104 and 106 and the cylindrical body 108 is too large, the stopper pin angle increases.

  Therefore, the optimum maximum value A1 of the stopper pin angle is determined from the characteristic diagram shown in FIG. 8, and the upper limit value CU1 of the gap determined by the maximum value A1 is determined from the relationship shown in FIG. Here, the maximum value A1 is the intersection X1 when the straight line L1 connecting the two points Y1 and Y2 of the torsional rigidity characteristic curve shown in FIG. It is assumed that the straight line L2 connecting the two points Y1 and -Y2 is represented by a difference from the intersection point X2 when intersecting the X axis. On the other hand, based on the maximum sliding resistance R1 according to the sliding resistance standard, the lower limit CL1 of the gap determined by the maximum sliding resistance R1 is determined from the relationship shown in FIG. Further, the tolerance of the outer diameter of the cylindrical body 108 can be determined based on the shaft spline diameter OPD1, the tube spline diameter BBD, and the allowable range (CU1-CL1) of the gap.

  Subsequently, the spline 103 changes the dimension of the spheroidal body 107 in the gap between the spheroidal body 107 and the measurement result of both spline groove dimensions and the gap between the spheroidal body 107 and the second group of spline grooves 103 and 105 obtained in advance by experiments or the like. Based on the relationship between the amount of preload applied to the preload structure (the leaf spring 109, which is an elastic body), the torsional rigidity in the axial circumferential direction, and the sliding resistance in the axial direction during expansion and contraction Select 107 dimensions. That is, if the amount of preload provided by the leaf spring 109 is too small, the torsional rigidity in the axial direction of the telescopic shaft becomes too low. On the other hand, if the amount of preload provided by the leaf spring 109 is too large, the sliding resistance increases and smooth expansion and contraction cannot be performed.

  Therefore, the average torsional rigidity TA is obtained by averaging the torsional rigidity, which is a hysteresis curve, from the characteristic diagram shown in FIG. 9, and the average torsional rigidity TA and the torsional rigidity standard are obtained from the relationship shown in FIG. The lower limit PL1 of the preload amount determined by is determined. On the other hand, based on the maximum sliding resistance R1 according to the sliding resistance standard, the upper limit value PU1 of the preload amount determined by the maximum sliding resistance R1 is determined from the relationship shown in FIG. Further, based on the shaft spline diameter OPD2 and the tube spline diameter BBD, the clearance between the spline grooves 103, 105 and the spherical body 107 is obtained, and based on the clearance and the tolerance of the preload amount (PU1-PL1). Thus, the tolerance of the outer diameter of the spherical body 107 can be determined.

  After the dimensions of the cylindrical body 108 and the spherical body 107 are selected in this way, the cylindrical body 108, the spherical body 107, and the leaf spring 109 having the selected dimensions are moved between the male shaft 101 and the female shaft 102 in step S104. The telescopic shaft is completed by incorporating it into. In the example of FIG. 5, the dimensions of the cylindrical body 108 and the spherical body 107 are selected in this order after measuring the spline groove dimension. However, after the dimension selection of the spherical body 107 is performed, Dimension selection may be performed, or both dimensions may be selected simultaneously.

  When the torque of the telescopic shaft is transmitted, the leaf spring 109 is elastically deformed to restrain the spherical body 107 in the circumferential direction, and the three rows of columnar bodies 108 interposed between the male shaft 101 and the female shaft 102 are the main torque. Play a role in communication.

  For example, when torque is input from the male shaft 101, the leaf spring 109 is preloaded in the initial stage, so there is no backlash, and the leaf spring 109 generates a reaction force against the torque and transmits the torque. . At this time, overall torque transmission is performed in a state where transmission torque and input torque between the male shaft 101, the leaf spring 109, the spherical body 107, and the female shaft 102 are balanced.

  As the torque further increases, the clearance in the rotational direction of the male shaft 101 and the female shaft 102 via the cylindrical body 108 disappears, and the subsequent torque increase is transferred to the cylindrical body via the male shaft 101 and the female shaft 102. 108 communicates. Therefore, it is possible to reliably prevent backlash in the rotational direction of the male shaft 101 and the female shaft 102 and transmit torque in a highly rigid state.

  As described above, according to the present embodiment, since the cylindrical body 108 is provided in addition to the spherical body 107, most of the load can be supported by the cylindrical body 108 when a large torque is input. Therefore, the contact pressure between the spline groove 105 of the female shaft 102 and the spherical body 107 can be reduced to improve durability, and torque can be transmitted in a highly rigid state when a large torque load is applied.

  Thus, according to the present embodiment, it is possible to realize stable sliding resistance, reliably prevent backlash in the rotational direction, and transmit torque in a highly rigid state.

  The spherical body 107 is preferably a rigid ball such as a steel ball. The rigid cylindrical body 108 is preferably a needle roller.

Since the cylindrical body (hereinafter referred to as a needle roller) 8 receives the load by line contact, it has various effects such as a lower contact pressure than a ball receiving a load by point contact. Therefore, the following items are superior to the case where the entire row has a ball rolling structure.
(1) The damping ability effect at the sliding part is larger than that of the ball rolling structure. Therefore, vibration absorption performance is high.
(2) Since the needle roller is in minute contact with the male shaft and the female shaft, the fluctuation range of the sliding resistance can be kept low, and vibration due to the fluctuation is not transmitted to the steering.
(3) If the same torque is transmitted, the contact pressure of the needle roller can be reduced, so that the axial length can be shortened and the space can be used effectively.
(4) If the same torque is transmitted, the needle roller can keep the contact pressure lower, so that an additional step for curing the surface of the spline groove of the female shaft by heat treatment or the like is unnecessary.
(5) The number of parts can be reduced.
(6) The assemblability can be improved.
(7) The assembly cost can be suppressed.

In this way, the needle roller serves as a key for transmitting torque between the male shaft 101 and the female shaft 102, and is in sliding contact with the inner peripheral surface of the female shaft 102. The use of the needle roller is superior to the conventional spline fitting as follows.
(8) The needle roller is a mass-produced product and is very low cost.
(9) Since the needle roller is polished after heat treatment, it has a high surface hardness and excellent wear resistance.
(10) Since the needle roller is polished, the surface roughness is fine and the friction coefficient during sliding is low, so that the sliding resistance can be kept low.
(11) Since the length and arrangement of the needle roller can be changed according to the use conditions, it is possible to deal with various applications without changing the design concept.
(12) Depending on the conditions of use, the friction coefficient during sliding may have to be further reduced. At this time, if only the needle roller is surface treated, its sliding characteristics can be changed, so the design philosophy is changed. Without being able to deal with various applications.
(13) Since needle rollers with different outer diameters can be manufactured in units of several microns at low cost, the gap between the male shaft, needle roller, and female shaft can be minimized by selecting the needle roller diameter. it can. Therefore, it is easy to improve the torsional rigidity of the shaft.

  Further, as described above, the leaf spring 109 is separated from the spherical body-side contact portion 109a that makes contact with the spherical body 107 at two points, and is separated from the spherical body-side contact portion 109a by a predetermined interval in the circumferential direction. The groove surface side contact portion 109b that contacts the planar side surface 103a of the spline groove 103 of the male shaft 101, and the spherical body side contact portion 109a and the groove surface side contact portion 109b are elastically biased in a direction away from each other. The urging portion 109c and the bottom surface 109d facing the bottom surface 103b of the spline groove 103 are paired on the left and right.

  The urging portion 109c has a substantially U shape and is bent in a substantially arc shape, and the spherical body side contact portion 109a and the groove surface side contact portion 109b are mutually connected by the bent urging portion 109c. Can be elastically biased so as to be separated from each other. Accordingly, the spherical spring side contact portion 109a of the leaf spring 109 can be sufficiently bent via the biasing portion 109b, and a sufficient amount of bending can be ensured.

  Accordingly, the leaf spring 109 has a space between the spherical body side contact portion 109 a that contacts the spherical body 107 and the groove surface side contact portion 109 b that contacts the spline groove 103, and the space is elastically connected therebetween. It is. Therefore, the stress generated at the contact portion between the spherical body 107 and the leaf spring 109 at the time of setting can be relieved, and sag of the leaf spring 109 due to permanent deformation can be prevented, and desired preload performance can be obtained over a long period of time. it can.

  Further, when the spherical body side contact portion 109a that contacts the spherical body 107 is formed in a substantially arc shape larger than the radius of the spherical body 107, the contact surface pressure with the spherical body 107 can be lowered than the planar shape, It is preferable.

  Further, the leaf spring 109 can secure a sufficient amount of bending, and the spherical body 107 and the leaf spring 109 are not subjected to an excessive load (stress). In addition, the stress generated at the contact point with the leaf spring 109 can be relieved, whereby high stress is not generated, and “sagging” due to permanent deformation is prevented, and preload performance is maintained over a long period of time. be able to.

  Furthermore, the contact point with the spherical body 107 is strong, and the portion exhibiting the spring property is easily bent so that a single member has both the race surface and the spring property. In the present embodiment, since the cylindrical body 108 mainly transmits torque, the structure is such that no excessive stress is generated between the male shaft 101, the female shaft 102, the leaf spring 109, and the spherical body 107.

  Therefore, it is necessary to prevent excessive stress from being generated in the leaf spring 109, to prevent the leaf spring 109 from sagging, to maintain desired preload performance over a long period of time, and to strictly control the dimensional accuracy. In addition, the leaf spring 109 and the race portion can be formed from a single material, and the manufacturing cost can be reduced by facilitating the assembly.

  As described above, the present invention has been described in detail with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be appropriately changed and improved without departing from the spirit thereof. Of course there is. For example, the mechanical component to which the present invention is applied is not limited to the telescopic shaft of the steering device.

1 is a side view of a steering mechanism portion of an automobile to which a telescopic shaft for vehicle steering according to an embodiment of the present invention is applied. It is a longitudinal cross-sectional view of the telescopic shaft for vehicle steering which concerns on embodiment of this invention. It is sectional drawing which cut | disconnected the structure of FIG. 2 by the III-III line | wire, and looked at the arrow direction. It is a perspective view of the leaf | plate spring which is an elastic body. It is a flowchart which shows each process of the assembly method of the expansion-contraction shaft concerning this Embodiment. It is a schematic sectional drawing which shows a tube spline internal diameter (BBD) measurement. It is a schematic sectional drawing which shows a shaft spline outer diameter (OPD) measurement. It is a figure which shows the stopper pin angle of the spline shaft (expandable shaft) obtained by experiment etc. previously, a vertical axis | shaft is a stopper pin angle and a horizontal axis is a rotation angle. It is a figure which shows the torsional rigidity of the spline shaft (expandable shaft) obtained beforehand by experiment etc., and a vertical axis | shaft is a stopper pin angle and a horizontal axis is a rotation angle. It is a figure for demonstrating the dimension selection of the spherical body. It is a figure for demonstrating the dimension selection of the cylindrical body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper bracket 2 Lower bracket 3 Steering shaft upper part 3A Steering column 3B Steering shaft 5 Steering wheel 6 Universal joint 7 Steering shaft lower part 8 Steering shaft joint 9 Pinion shaft 11 Elastic body 12 Steering rack shaft 13 Steering rack support member 101 Male shaft 101a Small diameter Part 102 Female shaft 103 Spline groove 103a Planar side surface 103b Bottom surface 104 Spline groove 105 Spline groove 106 Spline groove 107 Spherical body 108 Cylindrical body 109 Leaf spring 109a Spherical body side contact part 109b Energizing part 109b Groove surface side contact part 109c Energizing part 109d Bottom surface 110 Telescopic shaft 111 Stopper plate 112 Axial preload elastic body 113 Flat plate 115 Projection BBD Tube spline C1 inscribing circle C2 inscribed circle C3 circumscribed circle CL1 lower limit CU1 upper limit OPD1 shaft spline diameter OPD2 shaft spline diameter P1, P2 Pin P3 Pin PL1 lower limit PU1 upper limit R1 maximum sliding resistance VB body

Claims (2)

A spline female shaft having a spline groove on the inner periphery, a spline male shaft having a spline groove on the outer periphery, a first key component disposed in both the first group of spline grooves, and in the second group of both spline grooves In a method for assembling a machine part having a second key part and a preload structure arranged in
Measuring the spline groove dimension of the spline male shaft and the spline groove dimension of the spline female shaft;
Measurement results of both spline groove dimensions, clearance between the first group of both spline grooves and the first key parts obtained in advance through experiments, etc., axial sliding resistance during expansion and contraction, and axial stopper pins Selecting a dimension of the first key part based on a relationship with an angle;
Measurement result of both spline groove dimensions, and preload structure when the dimension of the second key part is changed in the gap between the second group of both spline grooves and the second key part obtained in advance through experiments or the like Selecting the dimension of the second key part based on the relationship between the amount of preload applied to the shaft, the torsional rigidity in the axial circumferential direction, and the sliding resistance in the axial direction during expansion and contraction;
And a step of incorporating the first key part and the second key part having the selected dimensions and the preload structure between the spline male shaft and the spline female shaft. How to assemble parts. 2. The method of assembling a machine part according to claim 1, wherein the machine part is a telescopic shaft used in a steering device.

Images