JP2011140998A - Power transmission shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power transmission shaft capable of reliably reducing vibration transmitted through a power transmission path by ensuring a durability in a high-temperature range. <P>SOLUTION: The power transmission shaft is a differential output shaft that includes an outer shaft 30, and an inner shaft 40 fitted to the outer shaft 30 in an angular direction relatively and displaceably. The shaft also includes: a recess 32 formed at an inner peripheral face 31 of the outer shaft 30; an face part 42 opposing to a recess formed at the outer peripheral surface 41 and at a position facing to the recess 32; and a plurality of rolling elements 52 comprising metal stored rotably in a housing chamber 51a defined by the recess 32 and the face part 42 opposing to a recess. The shaft is constituted so that the face part 42 opposing to a recess includes a tapered surface 42a formed to reduce a volume of the housing chamber 51a along with relative displacement to one side of an angular direction of the outer shaft 30 and the inner shaft 40. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power transmission shaft, and more particularly to a vehicle power transmission shaft provided in a power transmission path between a drive source mounted on a vehicle and drive wheels.

  In general, torque output from an engine mounted on a vehicle is input to a differential gear device via a torque converter, a transmission, and the like, and torque input to the differential gear device is transmitted between the differential gear device and a drive wheel. Is transmitted to the drive wheels via a vehicle power transmission shaft such as a drive shaft provided in a power transmission path (hereinafter referred to as a drive line) between the vehicle and the vehicle.

  In addition to the torque transmitted from the differential gear device, this kind of vehicle power transmission shaft transmits engine torque fluctuations associated with periodic cylinder ignition (explosion) and piston reciprocation. For this reason, the torsional vibration is generated in the vehicle power transmission shaft by using the rotation fluctuation due to the torque fluctuation described above as a forced source (vibration source, vibration forcing force). As a result, a booming noise is generated in the passenger compartment due to such torsional vibration.

In particular, from the viewpoint of improving fuel efficiency, the vehicle speed range (hereinafter referred to as the lockup range) where the lockup clutch of the torque converter provided in the power transmission path between the engine and the transmission is engaged is expanded to the low vehicle speed range. In this case, the engine output shaft and the transmission input shaft are directly connected in the low vehicle speed range, and the engine torque fluctuation is transmitted to the transmission input shaft without passing through the torque converter. . In such a case, a booming noise caused by torsional vibration in the drive line due to torque fluctuation in the low vehicle speed region is more prominently generated.
Therefore, it is desired to prevent the generation of torsional vibration that can be a cause of such a booming noise in the drive line.

  Conventionally, as a vehicle power transmission shaft for the purpose of suppressing vibration caused by this kind of engine rotation, it is provided in a drive line and fitted to a hollow outer shaft and an inner peripheral side of the outer shaft. A solid inner shaft, a convex part that protrudes radially inward from the inner peripheral surface of the outer shaft, and a convex part that is engraved radially inward from the outer peripheral surface of the inner shaft, and the convex part moves in the circumferential direction. A concave portion formed in a predetermined range in the circumferential direction as possible, and a buffer member made of an elastic material such as rubber interposed in a gap between the convex portion and the concave portion formed in the circumferential direction. Is known (see, for example, Patent Document 1).

  The vehicle power transmission shaft described in Patent Document 1 has a gap provided between a convex portion and a concave portion formed in the circumferential direction so as to suppress transmission of vibrations generated during idling of the vehicle. It has become. On the other hand, when the vehicle is traveling, power is transmitted from the differential gear device to the drive wheels via the convex and concave portions. Further, when the outer shaft and the inner shaft are rotated relative to each other, generation of rattling noise is prevented by the buffer member.

  Moreover, what is applied to a power transmission shaft such as a drive shaft is known as a fixed type constant velocity universal joint for the purpose of suppressing vibration transmitted in the power transmission path (see, for example, Patent Document 2). ).

  The conventional fixed type constant velocity universal joint described in Patent Document 2 includes an outer ring, an inner ring disposed radially inward of the outer ring, a ball interposed between the outer ring and the inner ring, and an outer ring and an inner ring. A fixed constant velocity universal joint provided with a cage for holding a ball, wherein the inner ring is composed of an inner member and an outer member. In this fixed type constant velocity universal joint, a protrusion extending in the axial direction is formed on the inner peripheral surface of the outer member, and the protrusion is fitted to the inner peripheral surface of the outer member via a predetermined gap in the rotation direction. Further, a vibration isolating member made of an elastic material such as rubber is interposed between the protrusions disposed between the inner member and the outer member at predetermined intervals in the rotation direction. Yes.

In the fixed type constant velocity universal joint described in Patent Document 2, vibration transmitted through the joint is absorbed by the vibration isolating member in the middle of the transmission.
On the other hand, when a torque load acts on the fixed type constant velocity universal joint and the inner member and the outer member are displaced relative to each other in the rotational direction, the ridge contacts the side surface of the groove, and the relative relationship between the inner member and the outer member increases. General displacement is regulated.

JP 2009-8186 A JP 2007-120665 A

  However, in the vehicle power transmission shaft and the fixed type constant velocity universal joint described in Patent Document 1 and Patent Document 2, both the buffer member and the vibration isolating member are made of an elastic material such as rubber. There was a problem that it was difficult to ensure the durability.

  As described above, in the conventional vehicle power transmission shaft and the fixed type constant velocity universal joint, since the durability in the high temperature range is lowered, the characteristics of the buffer member and the vibration isolating member are changed due to thermal deterioration. As a result, there is a problem that the suppression of vibration transmitted through the power transmission path is insufficient.

  Due to such problems, in the conventional vehicle power transmission shaft and the fixed type constant velocity universal joint, the drive line in the vicinity of the differential gear device that rises in temperature due to heat transfer from the engine or the exhaust pipe, etc. There was a problem that it was not suitable for installation.

  The present invention has been made in order to solve the above-described conventional problems. By ensuring durability in a high temperature range, power that can reliably reduce vibration transmitted through a power transmission path. An object is to provide a transmission shaft.

  In order to achieve the above object, a power transmission shaft according to the present invention has (1) an outer shaft having an inner peripheral surface, an outer peripheral surface facing the inner peripheral surface, and relative to the outer shaft in the circumferential direction. An inner shaft that is movably fitted to the outer shaft, and the power input to one of the outer shaft and the inner shaft can be transmitted to the other of the outer shaft and the inner shaft. A shaft, a recess formed in one of the inner peripheral surface of the outer shaft and the outer peripheral surface of the inner shaft, and any of the inner peripheral surface of the outer shaft and the outer peripheral surface of the inner shaft. A recess-facing surface portion formed at a position opposite to the recess, and the recess and the recess. A plurality of rolling elements made of metal that are slidably accommodated in a storage chamber defined by the opposing surface portion, wherein the concave facing surface portion is one of the outer shaft and the inner shaft in the circumferential direction. And a taper surface formed so that the volume of the storage chamber decreases with relative displacement.

  With this configuration, the concave portion facing surface portion has a tapered surface formed so that the volume of the storage chamber decreases with relative displacement of the outer shaft and the inner shaft in one circumferential direction. Therefore, the outer shaft and the inner shaft When a torque load is applied to the outer shaft and the inner shaft is relatively displaced in the circumferential direction, the volume of the storage chamber in which the plurality of rolling elements are stored is reduced.

  At this time, since the load resulting from the above-mentioned torque load is applied to the plurality of rolling elements accommodated in the accommodating chamber, a contact surface pressure is generated between the rolling elements, and Hertz stress is applied to each rolling element. Occurs. The Hertz stress remains within the elastic limit of each rolling element, and each rolling element is compressively deformed within the elastic limit. On the other hand, when the torque load is released, that is, when the Hertz stress becomes zero, each rolling element can return to its original shape.

For this reason, a spring characteristic is securable with respect to the relative displacement to the circumferential direction of an outer shaft and an inner shaft by several rolling elements. That is, even if the outer shaft and the inner shaft are relatively displaced, the torque load is released and the original state can be restored.
Therefore, the torsional vibration caused by the fluctuation of the torque transmitted to the power transmission shaft is attenuated by the spring characteristics secured by the plurality of rolling elements.

In addition, since the plurality of rolling elements housed in the housing chamber are made of metal, durability in a high temperature region can be improved, and changes in the spring characteristics of the power transmission shaft due to thermal degradation can be prevented.
For this reason, even when the power transmission shaft is used in a high temperature range, the spring characteristics due to the rolling elements do not change, and the torsion caused by the fluctuation of the torque transmitted through the power transmission shaft Vibration can be suitably damped.

  In order to achieve the above object, the power transmission shaft according to the present invention is the power transmission shaft according to the above (1), wherein (2) the tapered surface extends from either the inner peripheral surface or the outer peripheral surface to the outer surface. The shaft and the inner shaft are inclined in such a way that the volume of the storage chamber decreases as it goes in one of the circumferential directions in which the shaft and the inner shaft are relatively displaced and away from the recess.

  With this configuration, when a relative displacement occurs between the outer shaft and the inner shaft and the volume of the storage chamber decreases, the plurality of rolling elements contract within the compressed elastic limit. This contraction action attenuates torsional vibration caused by torque fluctuations.

  In order to achieve the above object, the power transmission shaft according to the present invention is the power transmission shaft according to (1) or (2), wherein (3) the outer peripheral surface of the outer shaft and the outer peripheral surface of the inner shaft are provided. A male spline is formed on one of the inner spurs and a female spline corresponding to the male spline is formed on the other of the inner peripheral surface of the outer shaft and the outer peripheral surface of the inner shaft. The spline is configured with a spline structure having a predetermined gap in the circumferential direction, and the male spline and the female spline are mutually connected when the relative displacement between the outer shaft and the inner shaft reaches a predetermined displacement amount. It has the structure to engage.

  With this configuration, the male spline and the female spline have a spline structure that engages with each other when the relative displacement between the outer shaft and the inner shaft reaches a predetermined displacement amount. When the torque load increases and the relative displacement between the outer shaft and the inner shaft reaches a predetermined displacement amount, the torque increased by the engagement of the male spline and the female spline (hereinafter referred to as high torque) It can be transmitted reliably.

  In order to achieve the above object, the power transmission shaft according to the present invention is configured such that any one of the power transmission shafts described in (1) to (3) is (4) power output from a drive source mounted on a vehicle. , A drive shaft that is provided on a power transmission path between the differential and the drive wheel and transmits power between the differential and the drive wheel, the drive shaft and the differential A power transmission shaft provided on a vehicle having a joint provided on the power transmission path between the differential and the joint, and a differential output plug provided on the power transmission path between the differential and the joint. Constitute the shaft.

  With this configuration, the power transmission shaft forms a differential output shaft provided on the power transmission path between the differential and the joint, so that the power transmission path in the vicinity of the differential that is particularly required to be durable in a high temperature range. It can be suitably implemented above.

  In order to achieve the above object, the power transmission shaft according to the present invention is the power transmission shaft according to the above (1) to (4), wherein (5) the rolling element is constituted by a needle rolling element.

  With this configuration, when the rolling element is a needle rolling element, a plurality of needle rolling elements accommodated in the accommodating chamber are associated with the relative displacement of the outer shaft and the inner shaft in the circumferential direction as compared with the spherical rolling element. The load capacity for a relatively large load applied to the moving body can be increased.

  In order to achieve the above object, the power transmission shaft according to the present invention is the power transmission shaft according to any one of (1) to (5), wherein (6) the concave portion, the concave portion facing surface portion, and the accommodating chamber are accommodated. A plurality of rolling elements constitute a compression spring portion, and at least two compression spring portions are provided, and one compression spring portion has the concave portion facing surface portion toward one of the circumferential directions of the outer shaft and the inner shaft. A taper surface formed so that the volume of the storage chamber decreases with relative displacement of the storage chamber, and the other compression spring portion has the concave facing surface portion in the circumferential direction of the outer shaft and the inner shaft. It has a tapered surface formed so that the volume of the storage chamber decreases with relative displacement to the other.

  With this configuration, when the outer shaft and the inner shaft are relatively displaced in one circumferential direction, the transmission is transmitted through the power transmission shaft by the spring characteristic secured by the plurality of rolling elements by one compression spring portion. The torsional vibration caused by the fluctuation of the applied torque can be attenuated. Further, when the outer shaft and the inner shaft are relatively displaced to the other in the circumferential direction, they are transmitted by the other compression spring portion through the power transmission shaft by the spring characteristics secured by the plurality of rolling elements. Torsional vibration caused by torque fluctuation can be attenuated.

  ADVANTAGE OF THE INVENTION According to this invention, the power transmission shaft which can reduce suitably the vibration transmitted through a power transmission path | route can be provided by ensuring durability in a high temperature range.

1 is a schematic configuration diagram showing an outline of a vehicle to which a power transmission shaft according to a first embodiment of the present invention is applied. It is a schematic block diagram which shows the structure of the torque converter which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows schematic structure of the power transmission device with which the power transmission shaft which concerns on the 1st Embodiment of this invention is applied. It is sectional drawing of the axial direction of the power transmission shaft which concerns on the 1st Embodiment of this invention. It is sectional drawing of the radial direction of the power transmission shaft which concerns on the 1st Embodiment of this invention. It is a partial expanded sectional view of the power transmission shaft which concerns on the 1st Embodiment of this invention. It is a graph which shows the characteristic of the power transmission shaft which concerns on the 1st Embodiment of this invention. It is a graph explaining the effect of the power transmission shaft which concerns on the 1st Embodiment of this invention. It is sectional drawing of the radial direction of the power transmission shaft which concerns on the 2nd Embodiment of this invention. It is a partial expanded sectional view of the power transmission shaft which concerns on the 2nd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
In the first embodiment of the present invention, the configuration of a vehicle including a power transmission shaft according to the present invention will be described with reference to the schematic configuration diagram of the vehicle shown in FIG.

First, the configuration will be described.
As shown in FIG. 1, a vehicle 1 according to the present embodiment (the whole is not shown) is a so-called FF vehicle of a front engine / front drive type, and is an engine as a drive source installed horizontally. 2, a transmission 3 that converts torque output from the engine 2, a differential 4 as a differential gear device connected to the output side of the transmission 3, and between the differential 4 and the left and right drive wheels 5 </ b> L, 5 </ b> R It is configured to include a pair of power transmission devices 6L, 6R provided in a power transmission path (hereinafter referred to as drive line). Here, the transmission 3 and the differential 4 constitute a transaxle 8.

  In the present embodiment, the case where the power transmission shaft is applied to an FF vehicle will be described. However, the present invention is not limited to this and may be applied to other drive type vehicles. For example, the present invention may be applied to a front engine / rear drive type FR vehicle.

  The engine 2 is a known power unit that outputs power by burning a mixture of hydrocarbon fuel such as gasoline or light oil and air in a combustion chamber of a cylinder (not shown). The engine 2 reciprocates the piston in the cylinder by repeatedly performing a series of steps of intake, compression, combustion and exhaust of the air-fuel mixture in the combustion chamber, and the crankshaft 2a connected to the piston so as to transmit power. (Refer to FIG. 2) is rotated.

  The type of the engine 2 is not particularly limited. For example, the engine 2 may be a gasoline engine such as an inline 4-cylinder or a diesel engine. Further, the fuel used for the engine 2 is not limited to the hydrocarbon fuel, but may be alcohol combustion including alcohol such as ethanol.

  The transmission 3 includes a torque converter 10 connected to the crankshaft 2a of the engine 2 and an automatic transmission (not shown), and the torque transmitted from the engine 2 to the torque converter 10 is desired by the automatic transmission. The torque is converted to a torque corresponding to the transmission ratio and transmitted to the differential 4.

  As shown in FIG. 2, the torque converter 10 includes a drive plate 11 connected to the crankshaft 2 a of the engine 2, a front cover 12 fixed to the drive plate 11, and a pump impeller 13 attached to the front cover 12. The turbine runner 14 attached to the input shaft 3a of the automatic transmission that extends substantially coaxially with the crankshaft 2a so as to face the pump impeller 13, and the stator 16 provided so as to be rotatable only in one direction by a one-way clutch 15. It is comprised including. The stator 16 is connected to the hollow shaft 18 via the one-way clutch 15. The input shaft 3 a of the automatic transmission is inserted into the hollow shaft 18.

  The torque converter 10 configured as described above transmits torque from the engine 2 transmitted via the crankshaft 2a to the input shaft 3a of the automatic transmission via fluid.

  The torque converter 10 includes a lockup clutch 19 between the pump impeller 13 and the turbine runner 14. The lockup clutch 19 connects the crankshaft 2 a of the engine 2 and the input shaft 3 a of the automatic transmission. They are integrally connected, that is, directly connected. The crankshaft 2a and the input shaft 3a that are directly connected by the lockup clutch 19 are configured to rotate integrally with each other. Thereby, the transmission efficiency in the vehicle 1 can be improved, and the fuel consumption of the vehicle 1 can be improved finally.

  The lockup clutch 19 is operated by hydraulic pressure, and can be engaged or released according to a predetermined lockup condition. When the lockup clutch 19 is engaged, the crankshaft 2a of the engine 2 and the input shaft 3a of the automatic transmission are directly connected.

  Further, engagement and disengagement of the lock-up clutch 19 are switched by controlling a solenoid valve (not shown) by an electronic control device (not shown) in accordance with detection results of various sensors mounted on the vehicle 1. It has become.

  Here, the torque output from the engine 2 varies with periodic cylinder ignition (explosion) of the engine 2 and reciprocating motion of the piston (hereinafter, such torque variation is simply referred to as torque variation). Such torque fluctuations can be absorbed by the torque converter 10 that transmits torque via fluid when the lock-up clutch 19 is not engaged. On the other hand, when the lockup clutch 19 is engaged, since the output side of the engine 2 and the input side of the automatic transmission are directly connected, such torque fluctuation is automatically generated from the crankshaft 2a of the engine 2. It will be transmitted directly to the input shaft 3a of the transmission without fluid.

In order to absorb such torque fluctuations, some damper mechanisms are provided between the lockup clutch 19 and the input shaft 3a of the automatic transmission, but the torque fluctuations have not been completely absorbed. For this reason, the torque fluctuation of the engine 2 may cause torsional vibration on the power transmission path, particularly in the drive line.
Therefore, in the present embodiment, a power transmission shaft, which will be described later, is provided in order to suppress torsional vibration in the drive line due to such torque fluctuation.

As shown in FIG. 1, the differential 4 is provided on a power transmission path between the transmission 3 and the left and right power transmission devices 6 </ b> L and 6 </ b> R, and torque output from the engine 2 is input via the transmission 3. It is like that. The differential 4 distributes and transmits the input torque to the left and right power transmission devices 6L and 6R.
Further, the differential 4 allows a difference in rotation between the left and right drive wheels 5L and 5R that occurs when the vehicle 1 turns.
The pair of power transmission devices 6L and 6R transmit the torque transmitted from the differential 4 to the drive wheels 5L and 5R, respectively.

  Next, details of the pair of power transmission devices 6L and 6R will be described with reference to FIG. 3 taking the power transmission device 6R as an example. Note that the power transmission device 6L has the same configuration as that of the power transmission device 6R, and a description thereof will be omitted.

  As shown in FIG. 3, the power transmission device 6 </ b> R is connected to a differential output shaft 20 as a power transmission shaft, a first joint 21 as a joint connected to the differential output shaft 20, and the first joint 21. The first drive shaft 22, the second joint 23 connected to the first drive shaft 22, and the second drive shaft 24 connected to the second joint 23 are configured. In addition, the 1st drive shaft 22 in this Embodiment comprises the drive shaft in this invention.

  The differential output shaft 20 has one end connected to the differential 4 (see FIG. 2) and the other end connected to the first joint 21. That is, the differential output shaft 20 is provided on a power transmission path between the differential 4 and the first joint 21, and transmits torque output from the differential 4 to the first joint 21.

The first joint 21 is composed of a constant velocity joint such as a tripod type or a double offset type mainly corresponding to a change in the axial direction of the drive wheel 5R of the drive wheel 5R (see FIG. 1). Reference numeral 23 denotes a constant velocity joint mainly corresponding to vertical movement such as a Zepper type or a Barfield type. In addition, the 1st joint 21 in this Embodiment comprises the coupling in this invention.
The second drive shaft 24 is connected at its end to a hub (not shown) of the drive wheel 5R (see FIG. 1).

  In the power transmission device 6R configured as described above, the torque output from the differential 4 is supplied to the differential output shaft 20, the first joint 21, the first drive shaft 22, the second joint 23, and the second drive shaft. 24 is transmitted to the drive wheels 5R.

  Further, torque fluctuations generated by periodic cylinder ignition (explosion) of the engine 2 and reciprocating motion of the piston are transmitted to the power transmission device 6R through the differential 4, and are twisted in each component of the power transmission device 6R. Cause vibration. In particular, as described above, this torque fluctuation is remarkably transmitted to the power transmission device 6R when the lockup clutch 19 is engaged.

  Therefore, in the power transmission device 6R according to the present embodiment, the differential output shaft 20 has the following configuration in order to attenuate torsional vibration caused by such torque fluctuation.

  As shown in FIGS. 4 and 5, the differential output shaft 20 is configured as a power transmission shaft having a divided structure that is divided into an outer shaft 30 and an inner shaft 40.

Here, the outer shaft 30 has an inner peripheral surface 31, the inner peripheral surface 31 includes a first inner peripheral surface 31a having a curvature radius R _1, the curvature radius R ₁ smaller than the radius of curvature R ₂ And a second inner peripheral surface 31b.

On the other hand, the inner shaft 40 has an outer peripheral surface 41 facing the inner peripheral surface 31 and is fitted to the outer shaft 30 so as to be relatively displaceable in the circumferential direction.
The outer peripheral surface 41 has a first outer peripheral surface 41a having a radius of curvature r ₁ slightly smaller than the radius of curvature R ₁ of the above, slightly smaller than the radius of curvature R ₂ of the above, and the radius of curvature r ₁ is less than the radius of curvature r ₂ And a second outer peripheral surface 41b having the structure.

In addition, the first outer peripheral surface 41 a of the inner shaft 40 faces the first inner peripheral surface 31 a of the outer shaft 30, and the second outer peripheral surface 41 b of the inner shaft 40 is the second inner peripheral surface 31 b of the outer shaft 30. Are facing each other. The curvature radius r ₁ and the curvature radius r ₂ are set slightly smaller than the curvature radius R ₁ and the curvature radius R ₂ because the outer shaft 30 and the outer shaft 30 are fitted inward in the radial direction. This is because the inner shaft 40 has a predetermined clearance between the outer shaft 30 and the inner shaft 40 so that the inner shaft 40 can be relatively displaced in the circumferential direction.

  The inner peripheral surface 31 of the outer shaft 30 in the present embodiment constitutes the inner peripheral surface of the outer shaft in the present invention, and the outer peripheral surface of the inner shaft 40 constitutes the outer peripheral surface of the inner shaft in the present invention.

The differential output shaft 20 has a plurality (three in the present embodiment) of compression spring portions 50a and 50b arranged at predetermined intervals in the circumferential direction.
The compression spring portion 50a functions as a compression spring portion when the inner shaft 40 is displaced in the direction indicated by the arrow A in the drawing or when the outer shaft 30 is displaced in the direction indicated by the arrow B in the drawing. Yes. The displacement of the inner shaft 40 and the outer shaft 30 at this time corresponds to a relative displacement of the outer shaft 30 and the inner shaft 40 in one circumferential direction.

  On the other hand, in contrast to the compression spring portion 50a, the compression spring portion 50b is formed when the inner shaft 40 is displaced in the direction indicated by the arrow B in the drawing or when the outer shaft 30 is displaced in the direction indicated by the arrow A in the drawing. It functions as a compression spring part. The displacement of the inner shaft 40 and the outer shaft 30 at this time corresponds to the relative displacement of the outer shaft 30 and the inner shaft 40 in the other circumferential direction.

Therefore, the compression spring portions 50a and 50b function as compression spring portions when the vehicle 1 is accelerated forward and when the vehicle 1 is decelerated forward or backward, respectively.
In the present embodiment, the number of compression spring portions 50a and 50b is three each. However, the number of compression spring portions 50a and 50b is not limited to this, and may be one each, or two or four or more. May be.

Next, a detailed configuration of the compression spring portions 50a and 50b having the functions as described above will be described with reference to FIG. 6 taking the compression spring portion 50a as an example.
As shown in FIG. 6, the compression spring portion 50 a includes a concave portion 32 formed on the inner peripheral surface 31 of the outer shaft 30 and a concave portion facing surface portion 42 formed on the outer peripheral surface 41 of the inner shaft 40 so as to face the concave portion 32. And a plurality of rolling elements 52 housed in a housing chamber 51a defined by the inner wall surface portion of the recess 32 and the recess facing surface portion 42 so as to be freely rollable.

  The concave portion 32 is carved from the inner peripheral surface 31 of the outer shaft 30 outward in the radial direction, and is composed of side wall surface portions 32a, 32b and a bottom surface portion 32c that face the circumferential direction as inner wall surfaces. The side wall surface portions 32a and 32b are formed so as to extend from the first inner peripheral surface 31a and the second inner peripheral surface 31b constituting the inner peripheral surface 31 of the outer shaft 30 toward the bottom surface portion 32c.

The recess facing surface portion 42 is formed continuously from the second outer peripheral surface 41b of the inner shaft 40 toward the first outer peripheral surface 41a, and has a tapered surface 42a formed at one end on the first outer peripheral surface 41a side. ing.
The tapered surface 42a is inclined in the direction indicated by the arrow A from the first outer peripheral surface 41a (see FIG. 5) toward the radially inward side away from the recess 32.

  Further, the accommodating chamber 51a is formed by the tapered surface 42a in accordance with the displacement of the inner shaft 40 in the direction indicated by the arrow A (see FIG. 5) or the displacement of the outer shaft 30 in the direction indicated by the arrow B (see FIG. 5). The volume is designed to decrease.

The rolling elements 52 are made of a metal needle rolling element formed in a columnar shape, and are accommodated in the accommodating chambers 51a as many as the rattling does not occur in the accommodating chamber 51a when the capacity of the accommodating chamber 51a is maximum. ing.
In addition, the rolling element is not limited to the needle rolling element, and may be a spherical rolling element made of, for example, high-hardness and low-cost high carbon steel. Moreover, in this Embodiment, although the diameter of each rolling element 52 was made into the same diameter, you may make it vary the diameter for every rolling element, without limiting to this.

The compression spring portion 50a configured in this manner is accompanied by the displacement of the inner shaft 40 in the direction indicated by the arrow A (see FIG. 5) or the displacement of the outer shaft 30 in the direction indicated by the arrow B (see FIG. 5). By reducing the volume of the storage chamber 51a, a load is applied to the plurality of rolling elements 52 stored in the storage chamber 51a by the tapered surface 42a.
Thereby, contact surface pressure is generated between the rolling elements 52, and Hertz stress is generated in the rolling elements 52.

  The compression spring portion 50b is the same as the compression spring portion 50a except for the point that it is formed so as to face the compression spring portion 50a in the circumferential direction.

  That is, when the inner shaft 40 is displaced in the direction indicated by the arrow B (see FIG. 5) or when the outer shaft 30 is displaced in the direction indicated by the arrow A (see FIG. 5), the compression spring portion 50b is stored in the storage chamber 51b. It is set as the above-mentioned structure so that the volume of (refer FIG. 5) can be reduced.

  Further, as shown in FIG. 5, the inner peripheral surface 31 of the outer shaft 30 has a plurality of spline grooves (in this embodiment, 3 in this embodiment) that are concave in the radial direction at predetermined intervals in the circumferential direction. ) Female spline 34 is formed.

  On the other hand, a plurality of male splines 44 are formed on the outer peripheral surface 41 of the inner shaft 40 as convex spline protrusions outward in the radial direction so as to correspond to the female splines 34. The male spline 44 is set to have a circumferential width smaller than the circumferential width of the female spline 34.

Therefore, the male spline 44 is fitted to the female spline 34 in the circumferential direction via the predetermined gaps d ₁ and d ₂ .
For this reason, the female spline 34 and the male spline 44 can be displaced in the circumferential direction indicated by arrows A and B in the figure by the gaps d ₁ and d ₂ . The gaps d ₁ and d ₂ are set to gaps that allow the outer shaft 30 and the inner shaft 40 to be displaced from each other by a predetermined angle θ (for example, 5 °) in the circumferential direction indicated by arrows A and B in the drawing.

  The predetermined angle θ described above is set to an optimum angle in accordance with specifications such as the material and dimensions of each component member such as the outer shaft 30 and the inner shaft 40. This angle θ corresponds to the amount of relative displacement between the outer shaft 30 and the inner shaft 40 in the circumferential direction.

The spline structure composed of the female spline 34 and the male spline 44 configured in this way is when the outer shaft 30 and the inner shaft 40 are displaced from each other by a predetermined angle θ in any one of the circumferential directions indicated by arrows A and B in the drawing. Further, the female spline 34 and the male spline 44 are engaged with each other.
In the present embodiment, the number of female splines 34 and male splines 44 is three. However, the number is not limited to this, and at least two or more are sufficient.

Next, the operation of the differential output shaft 20 according to the present embodiment will be described.
In the following description, the inner shaft 40 is connected to the differential 4 side and the outer shaft 30 is connected to the first joint 21 side. However, these connections are reversed. Have the same action, the description thereof is omitted.

As shown in FIG. 5, first, when no torque is applied to the inner shaft 40, the inner shaft 40 is held at a position where the female spline 34 and the male spline 44 have gaps d ₁ and d ₂ in the circumferential direction. Has been.

  In this state, when a relatively low torque (hereinafter referred to as low torque) is input from the differential 4 (see FIG. 1) to the inner shaft 40, the inner shaft 40 is rotated around the outer shaft 30 as indicated by an arrow A in the figure. Rotate, that is, displace in the direction.

At this time, the volume of the storage chamber 51a is reduced by the tapered surface 42a shown in FIG. Therefore, a load corresponding to the low torque input to the inner shaft 40 is applied to the plurality of rolling elements 52 accommodated in the accommodation chamber 51a via the tapered surface 42a. Act on. Thereby, contact surface pressure is generated between the rolling elements 52, and Hertz stress is generated in the rolling elements 52.
This Hertzian stress remains within the elastic limit of each rolling element 52, and each rolling element 52 is compressed and deformed within the elastic limit.

The inner shaft 40 is displaced in the circumferential direction indicated by the arrow A in the figure until the male spline 44 is engaged with the female spline 34 while increasing the load applied to the plurality of rolling elements 52. That is, the inner shaft 40 is displaced in the circumferential direction indicated by the arrow A in the drawing until the relative angle with respect to the outer shaft 30 reaches the predetermined angle θ.
At this time, the low torque input to the inner shaft 40 is transmitted to the outer shaft 30 via the compression spring portion 50a.

  Next, when high torque higher than low torque is input from the differential 4 to the inner shaft 40, the relative angle of the inner shaft 40 to the outer shaft 30 reaches a predetermined angle θ, and the male spline 44 is engaged with the female spline 34. Match. Thereby, the high torque input to the inner shaft 40 is transmitted to the outer shaft 30 via the female spline 34 and the male spline 44.

  Therefore, as shown in FIG. 7, the differential output shaft 20 has a predetermined torque by the compression spring portion 50a until the relative angle of the inner shaft 40 to the outer shaft 30 reaches a predetermined angle θ, that is, β (deg). To communicate. The predetermined torque transmitted at this time is a low torque up to α (N · m).

  On the other hand, after the relative angle of the inner shaft 40 with respect to the outer shaft 30 reaches a predetermined angle θ, that is, β (deg), the differential output shaft 20 is α (N · m) by the female spline 34 and the male spline 44. The above high torque is transmitted.

  Next, as shown in FIG. 8, the torque fluctuation is attenuated in the drive line as compared with the case where the differential output shaft 20 configured as described above is applied and the case where the differential output shaft having the conventional structure is applied. To explain.

  The graph indicated by the dotted line A in FIG. 8 is configured by a single power transmission shaft without applying a split structure such as the differential output shaft 20 according to the present embodiment to which the differential output shaft of the conventional structure is applied. FIG. 5 shows the attenuation of torque fluctuations in the drive line in the case where the configuration does not correspond to the compression spring portions 50a and 50b.

  On the other hand, the graph shown by the thick solid line B in the figure shows the attenuation of the torque fluctuation in the drive line in the case where the differential output shaft 20 according to the present embodiment is applied.

  Here, the horizontal axis in FIG. 8 is the engine speed Ne (rpm), and the vertical axis is the drive system torque fluctuation transmission rate Gv (dB). The drive system torque fluctuation transmission rate Gv (dB) is expressed by Gv (dB) = 20 log (Tg (N · m) when the torque fluctuation in the engine 2 is Te (N · m) and the torque fluctuation in the drive line is Tds (N · m). Tds / Te).

  As shown in FIG. 8, in the case where the differential output shaft 20 according to the present embodiment is applied, the drive system torque fluctuation transmission rate Gv (dB) is greatly reduced as compared with the conventional structure. Yes. In particular, even in the low engine speed Ne (rpm) region, the drive system torque fluctuation transmission rate Gv (dB) is reduced as compared with the prior art as indicated by the arrows in the figure.

  In other words, in the present embodiment, the torque transmitted from the engine 2 to the drive line via the differential 4 is reduced because the drive system torque fluctuation transmission rate Gv (dB) is reduced as compared with the conventional structure. The fluctuation can be attenuated significantly compared to the conventional structure. Therefore, in the present embodiment, the torsional vibration generated in the drive line due to the above-described torque fluctuation is greatly reduced as compared with the conventional structure.

  As described above, since the differential output shaft 20 according to the present embodiment is configured as described above, the following effects can be obtained.

  In the differential output shaft 20 according to the present embodiment, the concave facing surface portion 42 is relatively displaced in one of the circumferential directions of the outer shaft 30 and the inner shaft 40 (for example, the direction indicated by the arrow A in FIG. 5). Accordingly, the taper surface 42a is formed so that the volume of the storage chamber 51a is reduced.

  For this reason, when a torque load is applied to the inner shaft 40 and the outer shaft 30 and the inner shaft 40 are relatively displaced in one circumferential direction, the volume of the housing chamber 51a in which the plurality of rolling elements 52 are housed decreases. It becomes.

  At this time, since the load resulting from the above-mentioned torque load is applied to the plurality of rolling elements 52 accommodated in the accommodating chamber 51a, a contact surface pressure is generated between the rolling elements 52, and each rolling element 52 is provided. Hertzian stress is generated. This Hertzian stress remains within the elastic limit of each rolling element 52, and each rolling element 52 is compressed and deformed within the elastic limit. On the other hand, when the torque load is released, that is, when the Hertz stress becomes zero, each rolling element 52 can return to the original shape.

For this reason, the spring characteristics can be ensured by the plurality of rolling elements 52 against the relative displacement of the outer shaft 30 and the inner shaft 40 in the circumferential direction. That is, even if the outer shaft 30 and the inner shaft 40 are relatively displaced, the torque load is released and the original state can be restored.
Therefore, the torsional vibration caused by the torque fluctuation transmitted to the differential output shaft 20 is attenuated by the spring characteristics secured by the plurality of rolling elements 52.

  Further, since the plurality of rolling elements 52 housed in the housing chamber 51a are made of metal, durability in a high temperature region can be improved, and change in the spring characteristics of the differential output shaft 20 due to thermal deterioration can be prevented. Can do.

  For this reason, even when the differential output shaft 20 is used in a high temperature range, the spring characteristics by the plurality of rolling elements 52 do not change, and are caused by torque fluctuations transmitted through the differential output shaft 20. The generated torsional vibration can be suitably damped.

  In the differential output shaft 20 according to the present embodiment, the female spline 34 and the male spline 44 are engaged with each other when the relative angle between the outer shaft 30 and the inner shaft 40 reaches a predetermined angle α. A spline structure was adopted. Therefore, when the torque load applied to the outer shaft 30 and the inner shaft 40 increases and the relative angle between the outer shaft 30 and the inner shaft 40 reaches a predetermined angle α, the female spline 34 and the male spline 44 The high torque increased by the engagement can be reliably transmitted.

  Further, in the present embodiment, the differential output shaft 20 is provided on the power transmission path between the differential 4 and the first joint 21, so that the differential that requires durability particularly in a high temperature range is provided. 4 can be suitably implemented on a power transmission path in the vicinity of 4.

  Further, in the differential output shaft 20 according to the present embodiment, since the plurality of rolling elements 52 are constituted by needle rolling elements, the circumference of the outer shaft 30 and the inner shaft 40 is compared with a spherical rolling element. With a relative displacement in the direction, the load capacity for a relatively large load applied to the plurality of rolling elements 52 accommodated in the accommodation chamber 51a can be increased.

  Further, in the differential output shaft 20 according to the present embodiment, when the inner shaft 40 is displaced relative to the outer shaft 30 in one of the circumferential directions indicated by the arrow A in FIG. The torsional vibration caused by the torque fluctuation transmitted through the differential output shaft 20 by the spring characteristics secured by the plurality of rolling elements 52 can be attenuated by the portion 50a.

  On the other hand, when the inner shaft 40 is displaced relative to the other in the circumferential direction indicated by the arrow B in FIG. 5 with respect to the outer shaft 30, it is secured by the plurality of rolling elements 52 by the other compression spring portion 50b. The torsional vibration caused by the torque fluctuation transmitted through the differential output shaft 20 can be attenuated by the spring characteristics.

  In the present embodiment, the concave portion 32 constituting the compression spring portion 50a is formed on the outer shaft 30 side, and the concave portion facing surface portion 42 is formed on the inner shaft 40 side. 32 may be formed on the inner shaft 40 side, and the recessed portion facing surface portion 42 may be formed on the outer shaft 30 side.

  Further, in the present embodiment, the female spline 34 is formed on the outer shaft 30 side and the male spline 44 is formed on the inner shaft 40 side. The male spline 44 may be formed on the outer shaft 30 side.

  In the present embodiment, the differential output shaft 20 is divided into an outer shaft 30 and an inner shaft 40, and is configured as a power transmission shaft having compression spring portions 50a and 50b and a spline structure. However, instead of the differential output shaft 20, the second drive shaft 24 may be configured as a power transmission shaft having the above-described configurations. Even in this case, it is possible to obtain the effect as shown by the graph indicated by the thick solid line B in FIG.

Further, the same configuration as that of the differential output shaft 20 according to the present embodiment can be applied to the first drive shaft 22. Even in this case, it is possible to obtain the effect as shown in the graph indicated by the thin solid line C in FIG.
Furthermore, the same configuration as that of the differential output shaft 20 according to the present embodiment can be applied to a power transmission shaft provided in a power transmission path from the engine 2 to the drive wheels 5L and 5R, for example, a counter shaft. is there.

(Second Embodiment)
Next, with reference to FIG. 9, FIG. 10, the power transmission shaft which concerns on the 2nd Embodiment of this invention is demonstrated.

  In the power transmission shaft according to the present embodiment, the configuration of the compression spring portion is different from that of the power transmission shaft according to the first embodiment of the present invention, but the other configurations are substantially the same. Therefore, description will be made using the same reference numerals as those in the first embodiment shown in FIGS. 1 to 8, and only differences will be described in detail.

  As shown in FIG. 9, a differential output shaft 60 as a power transmission shaft according to the present embodiment includes an outer shaft 70 having an inner peripheral surface 71 and an inner shaft 80 having an outer peripheral surface 81 facing the inner peripheral surface 71. The power transmission shaft is divided into two parts.

Further, the differential output shaft 60 has a plurality of (four in this embodiment) compression spring portions 90 arranged at predetermined intervals in the circumferential direction.
The compression spring portion 90 functions as a compression spring portion when either the outer shaft 70 or the inner shaft 80 is displaced in the directions indicated by arrows A and B in the drawing.

Therefore, the compression spring part 90 functions as a compression spring part when the vehicle 1 is accelerated forward and when the vehicle 1 is forward decelerated or reversely driven.
In the present embodiment, the number of compression spring portions 90 is four. However, the number is not limited to this, and may be one or two or more.

Next, a detailed configuration of the compression spring portion 90 having the above-described function will be described with reference to FIG.
As shown in FIG. 10, the compression spring portion 90 includes a concave portion 72 formed on the inner peripheral surface 71 of the outer shaft 70 and a concave portion facing surface portion 82 formed on the outer peripheral surface 81 of the inner shaft 80 so as to face the concave portion 72. And a plurality of rolling elements 92 accommodated in the accommodating chambers 91a and 91b defined by the inner wall surface portion of the recess 72 and the recess facing surface portion 82.

The recess 72 is carved from the inner peripheral surface 71 of the outer shaft 70 outward in the radial direction.
The recessed portion facing surface portion 82 is formed so as to continuously extend in the circumferential direction from the outer peripheral surface 81 of the inner shaft 80. Furthermore, the recessed part opposing surface part 82 has the convex-shaped part 82a formed protruding toward radial direction outward.

  Tapered surfaces 82b and 82c constituting a part of the concave portion facing surface portion 82 are formed on the side surface in the circumferential direction of the convex portion 82a. The taper surface 82b is inclined in the direction indicated by the arrow A (see FIG. 9) from the apex portion 82d of the convex portion 82a and radially inwardly away from the concave portion 72. In contrast, the tapered surface 82c is inclined in the direction indicated by the arrow B from the apex portion 82d (see FIG. 9) and radially inwardly away from the recess 72.

  Further, the accommodating chamber 91a is formed by the tapered surface 82b in accordance with the displacement of the inner shaft 80 in the direction indicated by the arrow A (see FIG. 9) or the displacement of the outer shaft 70 in the direction indicated by the arrow B (see FIG. 9). The volume is designed to decrease.

  On the other hand, the accommodation chamber 91b is formed by the tapered surface 82c in accordance with the displacement of the inner shaft 80 in the direction indicated by the arrow B (see FIG. 9) or the displacement of the outer shaft 70 in the direction indicated by the arrow A (see FIG. 9). The volume is designed to decrease.

The rolling elements 92 are made of metal needle rolling elements, and are accommodated in the accommodating chambers 91a and 91b as many as the rattling does not occur in the accommodating chambers 91a and 91b when the capacity of the accommodating chambers 91a and 91b is maximum. ing.
In addition, the rolling element is not limited to the needle rolling element, and may be a spherical rolling element made of, for example, high-hardness and low-cost high carbon steel.

  Further, as shown in FIG. 9, the inner peripheral surface 71 of the outer shaft 70 has a plurality of spline grooves (in this embodiment, 2 in the present embodiment) that are concave in the radial direction at predetermined intervals in the circumferential direction. ) Female spline 74 is formed.

  On the other hand, a plurality of male splines 84 are formed on the outer peripheral surface 81 of the inner shaft 80 as convex spline protrusions outward in the radial direction so as to correspond to the female splines 74.

Note that the female spline 74 and the male spline 84 in the present embodiment are the same as those in the first embodiment except for the number of them. Therefore, detailed description thereof is omitted in the present embodiment.
In the present embodiment, the number of female splines 74 and male splines 84 is two, but the number is not limited to this, and may be three or more.

  The differential output shaft 60 having such a configuration is capable of corresponding to a relative circumferential displacement of the outer shaft 70 and the inner shaft 80 in one or the other by one compression spring portion 90, respectively. Although it is different from the compression spring portions 50a and 50b in the differential output shaft 20 according to the first embodiment, the operation thereof is the same as that of the differential output shaft 20 according to the first embodiment.

  That is, the differential output shaft 60 having a configuration in which the inner shaft 80 is connected to the differential 4 side and the outer shaft 70 is connected to the first joint 21 side will be described. The inner shaft 80 is indicated by an arrow A (see FIG. 9). When displaced in the circumferential direction, the volume of the storage chamber 91a is reduced by the tapered surface 82b shown in FIG. On the other hand, when the outer shaft 70 is displaced in the circumferential direction indicated by the arrow A (see FIG. 9), the volume of the storage chamber 91b is reduced by the tapered surface 82c shown in FIG. In addition, since it has the same effect | action even if connection of the above-mentioned outer shaft 70 and the inner shaft 80 is reverse, the description is abbreviate | omitted.

  As described above, since the differential output shaft 60 according to the present embodiment is configured as described above, the following effects are obtained in addition to the effects according to the first embodiment described above. .

  In the differential output shaft 60 according to the present embodiment, one compression spring portion 90 can cope with the relative displacement of the outer shaft 70 and the inner shaft 80 in one or the other in the circumferential direction. The structure can be simplified.

  As described above, the power transmission shaft according to the present invention has an effect that the vibration transmitted through the power transmission path can be surely reduced by ensuring durability in a high temperature range, and the vehicle It is useful for all power transmission shafts for vehicles provided in a power transmission path between a drive source and drive wheels mounted on the vehicle.

1 vehicle 2 engine (drive source)
4 differential 5L, 5R drive wheel 6L, 6R power transmission device 20, 60 differential output shaft (power transmission shaft)
21 First joint
22 First drive shaft (drive shaft)
30, 70 Outer shaft 31, 71 Inner peripheral surface 31a First inner peripheral surface 31b Second inner peripheral surface 32, 72 Recess 34, 74 Female spline 40, 80 Inner shaft 41, 81 Outer peripheral surface 41a First outer peripheral surface 41b Second Outer peripheral surface 42, 82 Concave facing surface portion 42a, 82b, 82c Tapered surface 44, 84 Male spline 50a, 50b, 90 Compression spring portion 51a, 51b, 91a, 91b Storage chamber 52, 92 Rolling element 82d Vertex portion

Claims (6)

An outer shaft having an inner peripheral surface, and an inner shaft having an outer peripheral surface facing the inner peripheral surface and fitted to the outer shaft so as to be relatively displaceable in the circumferential direction. A power transmission shaft capable of transmitting power input to either one of the shaft and the inner shaft to either the outer shaft or the inner shaft;
A recess formed in one of the inner peripheral surface of the outer shaft and the outer peripheral surface of the inner shaft;
A concave portion facing surface portion formed at a position opposite to the concave portion on the other side of the inner peripheral surface of the outer shaft and the outer peripheral surface of the inner shaft;
A plurality of rolling elements made of metal slidably accommodated in a storage chamber defined by the concave portion and the concave portion facing surface portion,
The power that is characterized in that the recess facing surface portion has a tapered surface formed so that the volume of the storage chamber decreases with relative displacement of the outer shaft and the inner shaft in one of the circumferential directions. Transmission shaft.   The taper surface is one of the circumferential directions in which the outer shaft and the inner shaft are relatively displaced from either one of the inner peripheral surface and the outer peripheral surface, and the taper surface moves in the radial direction away from the recess. The power transmission shaft according to claim 1, wherein the power transmission shaft is inclined so as to reduce the volume of the storage chamber. A male spline is formed on one of the inner peripheral surface of the outer shaft and the outer peripheral surface of the inner shaft,
A female spline corresponding to the male spline is formed on either the inner peripheral surface of the outer shaft or the outer peripheral surface of the inner shaft,
The male spline and the female spline are configured with a spline structure having a predetermined gap in the circumferential direction,
3. The power according to claim 1, wherein the male spline and the female spline are engaged with each other when a relative displacement between the outer shaft and the inner shaft reaches a predetermined displacement amount. Transmission shaft. A differential to which power output from a drive source mounted on the vehicle is input; and
A drive shaft that is provided on a power transmission path between the differential and the drive wheel, and that transmits power between the differential and the drive wheel;
A power transmission shaft provided in a vehicle provided with a joint provided on the power transmission path between the drive shaft and the differential,
The power transmission shaft according to any one of claims 1 to 3, wherein a differential output shaft provided on the power transmission path between the differential and the joint is configured.   The power transmission shaft according to any one of claims 1 to 4, wherein the rolling elements are needle rolling elements. A compression spring part is constituted by the plurality of rolling elements housed in the recessed part, the recessed part facing surface part and the storage chamber,
At least two or more compression springs are provided;
One compression spring portion has a tapered surface formed such that the concave portion facing surface portion is reduced in volume with respect to the outer shaft and the inner shaft relative to one of the circumferential directions in the circumferential direction. And
The other compression spring portion has a tapered surface formed so that the concave portion facing surface portion is reduced in volume with the relative displacement of the outer shaft and the inner shaft to the other in the circumferential direction. The power transmission shaft according to any one of claims 1 to 5, wherein:

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