JP2007154984A - Power transmission mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power transmission mechanism capable of improving durability even if declination of two connecting shafts becomes larger and capable of improving assembly operability. <P>SOLUTION: The power transmission mechanism includes a female spline part 4 provided in an inner circumference surface of an end part of a driven shaft 3, a male spline part 5 provided in an outer circumference surface of an end part of a driving shaft 2 and a rubber-like elastic body 6 interposed between the female and male spline parts. Both ends in a shaft direction of the female and male spline parts are more loosely meshed than center parts in the shaft direction. For example, an outer diameter of tooth shapes at both ends in the shaft direction of the male spline part is set to be smaller than that of a center part in the shaft direction and an inner diameter of tooth shapes at both ends in the shaft direction of the female spline is set to be larger than that of a center part in the shaft direction or thickness of teeth of both ends in the shaft direction in the female and male spline parts is thinner than that of the center parts in the shaft direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a power transmission mechanism in which a drive shaft and a driven shaft are spline-fitted and a rubber-like elastic body is interposed between the fitting portions.

In this type of power transmission mechanism, as shown in Patent Document 1, a drive shaft and a driven shaft are spline-fitted, and rubber for absorbing the eccentricity and declination of the shaft between the male spline and the female spline. The elastic body is interposed, so that it is possible to prevent the generation of annoying noise and vibration caused by the meshing of the metal teeth.
JP-A-2005-69470

  However, the tooth profile of the spline fitting portion is the same shape (parallel) in the axial direction, and if the deflection angle of the shaft increases, local stress concentration occurs in the rubber-like elastic body, and the durability of the rubber-like elastic body is increased. There was a problem that it decreased.

  Further, when assembling both the spline portions, if the clearance between both the members is small, there is a problem that the assembling workability is deteriorated if the tooth portions of the spline are parallel in the axial direction.

  In view of the above, the present invention improves the tooth shape of the spline part, and can improve the durability even if the deflection angle of the two connected shafts is increased, and can improve the assembly workability. The purpose is to provide a mechanism.

  In order to achieve the above object, a power transmission mechanism according to the present invention includes a female spline portion provided on an inner peripheral surface of one end of a drive shaft and a driven shaft, and an outer peripheral surface of an end portion of the other shaft. And a rubber-like elastic body interposed between the male spline portion and the female spline portion, and the meshing state of both ends of the male spline portion and the female spline portion in the axial direction is It is characterized by being set so as to engage more gently than the central portion in the direction.

  According to the above configuration, since the meshing state of both axial ends of both spline portions is set so as to mesh more gently than the central portion in the axial direction, the declination angle between the drive shaft to be connected and the driven shaft becomes large. However, local stress can be avoided from concentrating on the rubber-like elastic body interposed between the two spline portions, and the durability can be improved. Also, since the meshing state of both axial ends of both spline parts is more gradual than the central part in the axial direction, when assembling both spline parts, the clearance between both members becomes large and the assembling workability can be improved. it can.

  Here, in order to “engage the meshing state at both ends in the axial direction more gently than in the central part in the axial direction”, the following specific means can be employed.

  One is to set the outer diameter of the tooth profile at both axial ends of the male spline part to be smaller than the axial center part, and the other is to set the tooth profile inner diameter of the female spline part at the axial center at both axial ends. It is to set larger than the part.

  In both cases, even if the drive shaft and the driven shaft are deviated, contact between the corners of the axial ends of the male spline and female spline (tooth tip and bottom corner) can be avoided. Can be dispersed.

  As described above, the improvement of the tooth profile at both ends in the axial direction of the male spline portion and the improvement of the tooth profile at both ends in the axial direction of the female spline portion may be performed individually, or a combination of both may be used. Good.

  Furthermore, another means for “meshing the meshed state at both ends in the axial direction more gently than at the central portion in the axial direction” is the thickness of the teeth at both ends in the axial direction in at least one of the male and female spline portions. Is formed thinner than the central portion in the axial direction.

  According to the above configuration, even if a deviation occurs between the drive shaft and the driven shaft, stress concentration due to contact of the corners of the pressure surfaces at both ends of the internal teeth applied during torque transmission can be prevented, and the smooth curved surfaces The concentrated load can be dispersed by contact, and the driving torque can be transmitted.

  In addition, the configuration in which the thickness of the teeth at both ends in the axial direction in at least one of the spline portions is thinner than that in the central portion in the axial direction is adopted alone or in combination with an improvement applied to both ends in the axial direction of the male and female spline portions. May be.

  It should be noted that the rubber-like elastic body interposed between the male and female spline portions does not need to have teeth in particular. However, as a preferable configuration for reliably transmitting the driving torque, the female spline portion is engaged with the spline portion. It is desirable to use an elastic toothed sleeve having outer teeth on its outer peripheral surface and inner teeth on its inner peripheral surface that engage with the male spline portion.

  As described above, according to the present invention, the engagement state of both ends in the axial direction of the male and female spline portions is set so as to engage more gently than the central portion in the axial direction, so that the durability of the interposed rubber-like elastic body is improved. Can be made. Moreover, when assembling the male and female spline portions, the clearance between the axial ends of both members is increased, so that the assembly workability can be improved.

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

<First Embodiment>
FIG. 1 is a side view showing a spline fitting portion of a power transmission mechanism showing a first embodiment of the present invention, FIG. 2 (a) is a front view of a male spline portion, and FIG. Is a plan view of the tooth portion of the male spline portion, and FIG. 4 is a front view of the rubber-like elastic body.

  The power transmission mechanism 1 of this embodiment includes a female spline portion 4 provided on the inner peripheral surface of the end of the driven shaft 3, a male spline portion 5 provided on the outer peripheral surface of the end of the drive shaft 2, and the male spline portion. 5 and a rubber-like elastic body 6 interposed between the female spline part 4 so that the meshing state of the male spline part 5 and the female spline part 4 at both axial ends is more gently engaged than the axial center part. Is set to

  Specifically, the outer diameter of the tooth portion 7 is set smaller than the axial center portion at both axial ends of the male spline portion, and the tooth portion 7 is rounded like a drum as a whole. The R dimension (R1 in FIG. 2) is changed depending on the degree of inclination of the shaft (deflection angle θ).

Now, as shown in FIG. 2, when R1: tooth tip R, B: axial length of the male spline part, θ1: tooth tip R angle,
R1 = B / {2sin (θ1 / 2)} (1)
Is established.

Therefore, the condition for the teeth of the spline portion of the drive shaft to contact the rubber-like elastic body 6 with an arc is as follows:
2θ <θ1 <π (rad) (2)
Substituting equation (2) into equation (1) to find the optimum tip circle R1,
B / 2 <R1 <B / (2sinθ) (3)
It becomes.

Also, when considering the use conditions (allowable range) of the tip circle R1 that can be expected to improve durability,
θ <θ1 <π (rad) (4)
it is conceivable that.

Substituting equation (4) into equation (1),
B / 2 <R1 <B / {2sin (θ / 2)} (5)
The R shape of the tooth portion 7 is not limited to an arc shape, and may be a combined tooth shape in which the central portion in the axial direction is a straight line and both ends in the axial direction are R shapes.

Further, the thickness t2 of the teeth 7 at both axial ends of the male spline portion 5 and the female spline portion 5 is formed to be thinner than the tooth thickness t1 of the central portion in the axial direction. The thickness portion (pressure surface) is R-shaped (R2 in FIG. 3). Now, as shown in FIG. 3, when R2 is the tooth pressure surface R, B is the axial length of the male spline part, and θ2 is the pressure surface R angle,
R2 = B / {2sin (θ2 / 2)} (6)
Is established.

Therefore, the condition for the teeth of the spline portion of the drive shaft to contact the rubber-like elastic body 6 with an arc is as follows:
2θ <θ2 <π (rad) (7)
Substituting equation (7) into equation (6) to obtain the optimum tooth pressure surface R1,
B / 2 <R2 <B / (2sinθ) (8)
It becomes.

Also, when considering the use conditions (allowable range) of the tip circle R2 that can be expected to improve durability,
θ <θ2 <π (rad) (9)
it is conceivable that.

Substituting equation (9) into equation (6),
B / 2 <R2 <B / {2sin (θ / 2)} (10)
It becomes.

  Note that the pressure surface R shape of the tooth portion 7 is not limited to an arc shape, and may be a combined tooth shape in which a central portion in the axial direction is a straight line and both ends in the axial direction are R shapes.

  The rubber-like elastic body 6 has an external tooth 8 that is spline-fitted with the female spline portion 4 on the outer peripheral surface, and an elastic tooth that has an inner tooth 9 that is spline-fitted with the male spline portion 5 on the inner peripheral surface. It is a sleeve with. As the toothed sleeve, one having a tooth surface covered with a tooth cloth and / or a core wire embedded therein may be employed. Further, the rubber-like elastic body 6 is not limited to the one having teeth formed as described above, and one having no teeth may be used. Furthermore, the rubber-like elastic body 6 may be not only various rubber materials such as natural rubber and synthetic rubber, but also various resin materials having rubber-like elasticity.

  In the above configuration, the meshing state of both ends in the axial direction of both spline portions is set so as to mesh more gently than the central portion in the axial direction. Therefore, even if the deflection angle θ between the driving shaft 2 and the driven shaft 3 to be connected increases, it is possible to avoid local stress from being concentrated on the rubber-like elastic body 6 interposed between the two spline portions. And durability can be improved.

  Also, since the meshing state of both axial ends of both spline parts is more gradual than the central part in the axial direction, when assembling both spline parts, the clearance between both members becomes large and the assembling workability can be improved. it can.

  In particular, if the tooth tip θ1 is set to 2θ or more, even if a deviation angle θ occurs between the drive shaft 2 and the driven shaft 3, the corner portions (tooth tip and tooth tip) of both the male spline portion 5 and the female spline portion 6 in the axial direction. It is possible to avoid contact with the corners of the tooth base, and to distribute the concentrated load.

  As for the tooth thickness t, if the pressure surface of the tooth 7 has an R shape so that the thickness is reduced at both ends in the axial direction, even if a deviation angle θ occurs between the drive shaft 2 and the driven shaft 3, it is applied during torque transmission. Stress concentration due to contact of the corners of the pressure surfaces at both ends of the teeth can be prevented, and contact with the surfaces can be prevented by the smooth R portion to prevent concentrated loads, and driving torque can be transmitted.

  In addition, the processing of the spline tooth part of such a power transmission mechanism manufactures a dedicated hob, and processes it with an NC hobbing machine. Further, mass production can be performed by sintering, rolling, pressing, electric discharge machining, or the like.

<Second Embodiment>
FIG. 5 is a side view showing a state in which the spline fitting portion of the power transmission mechanism showing the second embodiment of the present invention is disassembled, and illustration of the rubber-like elastic body 6 is omitted.

  In the present embodiment, the female spline portion 4 provided on the inner peripheral surface of the end portion of the driven shaft 3, the male spline portion 5 provided on the outer peripheral surface of the end portion of the drive shaft 2, and the male and female spline portions are interposed. And the inner diameter of the tooth profile 10 is set to be larger than the central portion in the axial direction at both axial ends of the female spline portion 4. Moreover, the thickness of the tooth | gear part 7 of the axial direction both ends in the male and female spline parts 4 and 5 is formed thinner than the axial center part.

  Even in the above-described configuration, even if the deflection angle θ is generated between the drive shaft 2 and the driven shaft 3, the corners of the both ends in the axial direction of the male spline part 5 and the female spline part 4 (the corners of the tooth tip and the tooth bottom, And corners of the tooth pressure surface) can be avoided, and the concentrated load can be dispersed.

  In addition, this invention is not limited to said embodiment, A change can be suitably added within the scope of the present invention. For example, in the above embodiment, the female spline portion 4 is formed on the driven shaft 3 and the male spline portion 5 is formed on the drive shaft 2. However, the female spline portion is formed on the drive shaft and the male spline portion is formed on the driven shaft. May be formed.

  In addition to the above embodiment, the present invention sets the outer diameter of the tooth profile at both axial ends of the male spline portion to be smaller than the axial central portion, and sets the inner diameter of the tooth profile at both axial ends of the female spline portion. It may be set larger than that, and the thickness of teeth at both ends in the axial direction in at least one of the male and female spline portions may be formed thinner than the central portion in the axial direction.

The side view which shows the spline fitting part of the power transmission mechanism which shows the 1st Embodiment of this invention. (A) is a front view of the male spline part, and (b) is a side view of the same. Top view of teeth on male spline Front view of rubber-like elastic body The side view which shows the state which decomposed | disassembled the spline fitting part of the power transmission mechanism which shows the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power transmission mechanism 2 Drive shaft 3 Driven shaft 4 Female spline part 5 Male spline part 6 Rubber-like elastic body 7 Tooth part

Claims (7)

A female spline portion provided on the inner peripheral surface of one end of the drive shaft and the driven shaft, a male spline portion provided on the outer peripheral surface of the end portion of the other shaft, and the male spline portion and the female spline portion A rubber-like elastic body interposed between the male spline part and the female spline part. Power transmission mechanism. A female spline portion provided on the inner peripheral surface of one end of the drive shaft and the driven shaft, a male spline portion provided on the outer peripheral surface of the end portion of the other shaft, and the male spline portion and the female spline portion And a rubber-like elastic body interposed between the male spline portion and a tooth-shaped outer diameter at both ends in the axial direction of the male spline portion smaller than that of the central portion in the axial direction. A female spline portion provided on the inner peripheral surface of one end of the drive shaft and the driven shaft, a male spline portion provided on the outer peripheral surface of the end portion of the other shaft, and the male spline portion and the female spline portion And a rubber-like elastic body interposed between the two and the female spline portion, the tooth profile inner diameter being set larger than the axial central portion at both axial ends. 4. The power transmission mechanism according to claim 2, wherein a thickness of teeth at both ends in the axial direction in at least one of the male spline portion and the female spline portion is formed thinner than a central portion in the axial direction. A female spline portion provided on the inner peripheral surface of one end of the drive shaft and the driven shaft, a male spline portion provided on the outer peripheral surface of the end portion of the other shaft, and the male spline portion and the female spline portion A rubber-like elastic body interposed between the male spline part and the female spline part. A power transmission mechanism. A female spline portion provided on the inner peripheral surface of one end of the drive shaft and the driven shaft, a male spline portion provided on the outer peripheral surface of the end portion of the other shaft, and the male spline portion and the female spline portion A rubber-like elastic body interposed between the male spline part, the tooth profile outer diameter at each axial end of the male spline part is set to be smaller than the axial center part, and the tooth profile inner diameter at each axial end of the female spline part The power transmission is characterized in that it is set larger than the central portion, and further, the thickness of the teeth at both ends in the axial direction in at least one of the male spline portion and the female spline portion is formed thinner than the axial central portion. mechanism. The rubber-like elastic body is an elastic toothed sleeve having outer teeth that engage with the female spline portion on the outer peripheral surface and inner teeth that engage with the male spline portion on the inner peripheral surface thereof. The power transmission mechanism according to any one of claims 1 to 6.

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