JP2018155259A - Cam mechanism and drive force transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cam mechanism which does not need to planarly process an end face of one cam member in an axial direction at a side opposite to the other cam member while forming one cam member which receives a reaction force of cam thrust out of a pair of the relatively-rotating cam members by sintering, and a drive force transmission device having the cam mechanism.SOLUTION: In a cam mechanism 4 having a pilot cam 41 and a main cam 42 which are formed of sintered bodies, and cam balls 43 which can roll in cam grooves 410, 420 formed at the cam members, respectively, a part of an end face 41b of the pilot cam 41 in an axial direction at a side opposite to the main cam 42 is formed as an output face 41bcomposed of a sintered skin for outputting a reaction force of cam thrust, an area including at least a part of a region being a back side of the deepest part 410b of the cam groove 410 and a region being an outside-diameter side and an inside-diameter side of the region is recessively formed in the axial direction rather than a vicinity area 41h in a peripheral direction, and the recessively-formed area is not included in the output face 41b.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a cam mechanism and a driving force transmission device including the cam mechanism.

  2. Description of the Related Art Conventionally, a driving force transmission device that can adjust a driving force transmitted according to a supplied current is used in a driving force transmission system that transmits driving force to auxiliary driving wheels of a four-wheel drive vehicle, for example. Such a driving force transmission device includes a cam mechanism that generates an axial cam thrust along the rotation axis direction by relative rotation of a pair of cam members, and a clutch that is pressed by the cam thrust of the cam mechanism. (For example, refer to Patent Document 1).

  The driving force transmission device described in Patent Document 1 is capable of torque transmission between an outer housing as an outer rotating member and an inner shaft as an inner rotating member, which are arranged to be relatively rotatable on a coaxial rotation axis, and the outer housing and the inner shaft. A main clutch coupled to the main clutch, a cam mechanism for generating a cam thrust force for pressing the main clutch in the axial direction, and an electromagnetic clutch mechanism for operating the cam mechanism.

  The cam mechanism generates cam thrust by relative rotation of the pair of cam members. Specifically, the main cam as one cam member connected to the inner shaft so as to be axially movable and relatively non-rotatable, and the other cam member arranged so as not to be axially moveable and relatively rotatable relative to the outer housing. A cam mechanism is constituted by a pilot cam as a cam member and a plurality of spherical rolling elements capable of rolling in cam grooves formed in each of the main cam and the pilot cam. The moving body rolls in the cam groove to generate cam thrust.

  The electromagnetic clutch mechanism has a pilot clutch that transmits torque for rotating the pilot cam relative to the main cam, and a part of the rotational force of the outer housing with respect to the inner shaft is transmitted to the pilot cam via the pilot clutch. . A straight spline fitting portion is formed on the outer peripheral surface of the pilot cam so that the clutch plate of the pilot clutch is fitted so as not to be relatively rotatable and axially movable.

  The outer housing has a bottomed cylindrical first housing member and a second housing member that closes the opening side of the first housing member. A thrust roller bearing is disposed between the pilot cam and the second housing member. The thrust roller bearing makes the pilot cam rotatable relative to the second housing member while receiving a reaction force of the cam thrust generated by the cam mechanism. In the pilot cam, a part of the axial end surface opposite to the surface facing the main cam in which the cam groove is formed is in contact with the thrust roller bearing, and the thrust force is applied to the thrust roller bearing from the contact surface. Output to.

JP 2014-114833 A

  Since the shape of the pilot cam is complicated, it can be considered that the pilot cam is formed by sintering using a mold. However, in the experiments by the present inventors, it was confirmed that the durability life of the thrust roller bearing is shortened when the driving force transmission device is configured as described above using the sintered pilot pilot cam as it is. . As a result of earnest research on the cause, the present inventor has found that a load is applied to a part of the thrust roller bearing in the central axis direction due to irregularity (partial bulging) of the contact surface of the pilot cam with the thrust roller bearing. Concentrated and confirmed that flaking and local wear occurred. For this reason, when using a pilot cam formed by sintering, the axial end surface opposite to the surface on which the cam groove is formed must be planarized by grinding or the like. Cost increases.

  The present invention has been made in view of the above circumstances, and its purpose is to form one cam member that receives a reaction force of cam thrust among a pair of relative rotating cam members by sintering, It is an object of the present invention to provide a cam mechanism that does not require planar machining of an axial end surface of one cam member opposite to the other cam member, and a driving force transmission device including the cam mechanism.

  In order to achieve the above object, the present invention provides a first cam member made of a sintered body formed in an annular shape, and an annular second cam member arranged in parallel in the axial direction so as to be relatively rotatable with the first cam member. And a spherical rolling member capable of rolling the first cam groove formed in the first cam member and the second cam groove formed in the second cam member, wherein the rolling member is the first cam groove. A cam mechanism in which the second cam member moves in an axial direction with respect to the first cam member by a cam thrust generated by rolling the one cam groove and the second cam groove, wherein the first cam groove And the second cam groove is a curved shape having a radial cross-sectional shape having a radius of curvature corresponding to the radius of the rolling member, and the axial depth is gradually shallower as the distance from the deepest portion in the circumferential direction increases. And the first cam member is a second groove. A part of the axial end surface opposite to the member is formed as an output surface made of a sintered skin that outputs a reaction force of the cam thrust, and the axial end surface of the first cam member is formed by the first cam groove. A region that includes at least a part of a portion corresponding to the back side of the deepest portion and a portion corresponding to the outer diameter side and the inner diameter side of the portion is formed to be recessed in the axial direction from the peripheral region in the circumferential direction. Is not included in the output surface.

  In order to achieve the above object, the present invention provides relative rotation between the cam mechanism, the first rotating member and the second rotating member that are coaxially arranged to be relatively rotatable, and the first rotating member. A multi-plate clutch having a regulated first friction plate and a second friction plate restricted in relative rotation with the second rotating member, and rotation for rotating the first cam member relative to the second cam member A rotational force imparting mechanism that imparts a force, and is disposed between the axial end surface of the first cam member and the first rotational member, and restricts axial movement of the first cam member relative to the first rotational member. And a thrust roller bearing that receives a reaction force of the cam thrust output from the output surface, and the second cam member moves in the axial direction with respect to the first cam member, so that the multi-plate clutch The first friction plate and the second friction plate Frictionally engage, the driving force between the second rotary member and the first rotating member is transmitted, to provide a driving force transmission apparatus.

  According to the present invention, one cam member that receives the reaction force of the cam thrust among the pair of cam members that rotate relative to each other is formed by sintering, but the one cam member is opposite to the other cam member. It is not necessary to machine the end face in the axial direction, and the manufacturing cost of the cam mechanism and the driving force transmission device can be suppressed.

It is a schematic block diagram which shows the example of a schematic structure of the four-wheel drive vehicle by which the drive force transmission apparatus provided with the cam mechanism which concerns on embodiment of this invention was mounted. It is sectional drawing which shows the structural example of the driving force transmission apparatus which concerns on 1st Embodiment. It is an expanded sectional view which expands and shows a cam mechanism and its peripheral part. (A) is a top view which shows one axial direction end surface in a pilot cam, (b) is a top view which shows the other axial direction end surface in a pilot cam. It is a cross-sectional perspective view of the pilot cam which shows the AA line cross section of FIG. (A) And (b) is AA sectional drawing and BB sectional drawing of the pilot cam shown in FIG.4 (b). (A) And (b) is radial direction sectional drawing which shows the pilot cam which concerns on a comparative example. The pilot cam which concerns on 2nd Embodiment is shown, (a) is a top view which shows one axial direction end surface, (b) is a top view which shows the other axial direction end surface. FIG. 9 is a cross-sectional perspective view of the pilot cam showing a cross section taken along the line CC of FIG.

[First Embodiment]
A first embodiment of the present invention will be described with reference to FIGS. In addition, although embodiment described below is shown as a suitable specific example in implementing this invention, although there are some parts which have illustrated various technical matters that are technically preferable. The technical scope of the present invention is not limited to this specific embodiment.

  FIG. 1 is a schematic configuration diagram showing a schematic configuration example of a four-wheel drive vehicle on which a driving force transmission device including a cam mechanism according to a first embodiment of the present invention is mounted.

  As shown in FIG. 1, the four-wheel drive vehicle 1 is shifted by an engine 11 as a drive source that generates torque (driving force) for traveling, a transmission 12 that changes the output of the engine 11, and the transmission 12. Left and right front wheels 181 and 182 as main drive wheels to which the driving force of the engine 11 is always transmitted, and left and right rear wheels as auxiliary drive wheels to which the driving force of the engine 11 is transmitted according to the traveling state of the four-wheel drive vehicle 1 191 and 192. The four-wheel drive vehicle 1 includes a four-wheel drive state in which the drive force of the engine 11 is transmitted to the left and right front wheels 181 and 182 and the left and right rear wheels 191 and 192, and a two-wheel drive state in which the drive force is transmitted only to the left and right front wheels 181 and 182. And can be switched.

  The four-wheel drive vehicle 1 includes a front differential 13, a propeller shaft 14, a rear differential 15, drive shafts 161 and 162 on the left and right front wheels, drive shafts 171 and 172 on the left and right rear wheels, A driving force transmission device 2 disposed between the propeller shaft 14 and the rear differential 15 and a control device 10 for controlling the driving force transmission device 2 are mounted.

  The control device 10 detects the rotational speed sensors 71 to 74 for detecting the rotational speeds of the left and right front wheels 181 and 182 and the left and right rear wheels 191 and 192, respectively, and the detection result of the accelerator pedal sensor 75 for detecting the depression amount of the accelerator pedal 100. And the driving force transmission device 2 is controlled based on these detection results. More specifically, for example, the greater the difference between the average rotational speed of the left and right front wheels 181 and 182 and the average rotational speed of the left and right rear wheels 191 and 192, and the greater the amount of depression of the accelerator pedal 100, the greater the driving force increases. The driving force transmission device 2 is controlled so as to be transmitted to the rear wheels 191 and 192.

  The control device 10 calculates a command torque to be transmitted by the driving force transmission device 2 based on detection results of the rotational speed sensors 71 to 74 and the accelerator pedal sensor 75, and transmits an excitation current corresponding to the command torque to the driving force. Supply to device 2. The driving force transmission device 2 transmits a driving force corresponding to the exciting current from the propeller shaft 14 to the rear differential 15 side. The control device 10 can adjust the driving force transmitted to the left and right rear wheels 191 and 192 via the driving force transmission device 2 by increasing or decreasing the excitation current by, for example, PWM control.

  The driving force of the engine 11 is transmitted to the left and right front wheels 181 and 182 through the transmission 12, the front differential 13, and the left and right front wheel side drive shafts 161 and 162. The front differential 13 includes a pair of side gears 131 and 131 that are coupled to the left and right front wheel drive shafts 161 and 162 so as not to rotate relative to each other, and a pair of pinion gears that mesh with the pair of side gears 131 and 131 with their gear axes orthogonal to each other. 132, 132, a pinion gear shaft 133 that supports the pair of pinion gears 132, 132, and a front differential case 134 that accommodates these.

  A ring gear 135 is fixed to the front differential case 134, and the ring gear 135 meshes with a pinion gear 141 provided at an end of the propeller shaft 14 on the vehicle front side. The end of the propeller shaft 14 on the vehicle rear side is connected to the housing 20 of the driving force transmission device 2. The driving force transmission device 2 has an inner shaft 23 that is disposed so as to be rotatable relative to the housing 20, so that the driving force corresponding to the excitation current supplied from the control device 10 cannot be rotated relative to the inner shaft 23. It is transmitted to the rear differential 15 through the connected pinion gear shaft 150. Details of the driving force transmission device 2 will be described later.

  The rear differential 15 includes a pair of side gears 151 and 151 that are coupled to the left and right rear wheel side drive shafts 171 and 172 so as not to rotate relative to each other, and a pair of side gears 151 and 151 that mesh with the pair of side gears 151 and 151 orthogonal to each other. Pinion gears 152, 152, a pinion gear shaft 153 that supports the pair of pinion gears 152, 152, a rear differential case 154 that accommodates these, and a ring gear 155 that is fixed to the rear differential case 154 and meshes with the pinion gear shaft 150.

(Configuration of driving force transmission device)
FIG. 2 is a cross-sectional view illustrating a configuration example of the driving force transmission device 2. FIG. 3 is an enlarged cross-sectional view showing the cam mechanism 4 of the driving force transmission device 2 and its peripheral portion in an enlarged manner. In FIG. 2, the upper side of the rotation axis O indicates the operating state (torque transmission state) of the driving force transmission device 2, and the lower side indicates the non-operational state (torque non-transmission state) of the driving force transmission device 2. Hereinafter, a direction parallel to the rotation axis O is referred to as an axial direction.

  The driving force transmission device 2 includes a housing 20 as a first rotating member including a front housing 21 and a rear housing 22, and a cylindrical inner shaft as a second rotating member that is coaxially supported with the housing 20 and is supported so as to be relatively rotatable. 23, a main clutch 3 disposed between the housing 20 and the inner shaft 23, a cam mechanism 4 that generates a pressing force to press the main clutch 3, and a cam mechanism 4 that receives the rotational force of the front housing 21. And an electromagnetic clutch mechanism 5 to be operated. Lubricating oil (not shown) is sealed in the internal space of the housing 20. In the present embodiment, the cam mechanism 4 is configured as a ball cam mechanism. The housing 20 and the inner shaft 23 are one mode of a pair of rotating members in a driving force transmission path that transmits driving force to the left and right rear wheels 191 and 192.

  The front housing 21 has a bottomed cylindrical shape integrally including a cylindrical tube portion 21a and a bottom portion 21b. A female screw portion 21c is formed on the inner surface at the open end of the cylindrical portion 21a. The front housing 21 is made of a non-magnetic metal material such as aluminum, and the propeller shaft 14 (see FIG. 1) is connected to the bottom 21b through, for example, a cross joint.

  The front housing 21 has a plurality of outer spline protrusions 211 extending in the axial direction on the inner peripheral surface of the cylindrical portion 21a. The outer spline protrusion 211 protrudes radially inward toward the rotation axis O of the housing 20 and the inner shaft 23.

  The rear housing 22 includes a first annular member 221 made of a magnetic material such as iron, and a second annular member made of a non-magnetic material such as austenitic stainless steel integrally joined to the inner peripheral side of the first annular member 221 by welding or the like. 222 and a third annular member 223 made of a magnetic material such as iron integrally coupled to the inner peripheral side of the second annular member 222 by welding or the like. Between the first annular member 221 and the third annular member 223, an annular accommodating space 22a for accommodating the electromagnetic coil 53 is formed. Further, a male screw portion 221 a that is screwed into the female screw portion 21 c of the front housing 21 is formed on the outer peripheral surface of the first annular member 221.

  The inner shaft 23 is supported on the inner peripheral side of the housing 20 by a ball bearing 61 and a needle roller bearing 62. The inner shaft 23 has a plurality of inner spline protrusions 231 extending in the axial direction on the outer peripheral surface. A spline fitting portion 232 is formed on the inner surface of one end portion of the inner shaft 23 so that the one end portion of the pinion gear shaft 150 (see FIG. 1) is fitted so as not to be relatively rotatable.

  The main clutch 3 is a multi-plate clutch having a plurality of main outer clutch plates 31 as first friction plates and a plurality of main inner clutch plates 32 as second friction plates, which are alternately arranged along the axial direction. The frictional sliding between the main outer clutch plate 31 and the main inner clutch plate 32 is lubricated by an unillustrated lubricating oil enclosed between the housing 20 and the inner shaft 23, and wear and seizure are suppressed.

  The main outer clutch plate 31 has a plurality of engaging protrusions 311 that engage with the outer spline protrusions 211 of the front housing 21 at the outer peripheral end. The main outer clutch plate 31 is restricted in relative rotation with the front housing 21 by the engagement protrusion 311 engaging the outer spline protrusion 211 and is movable in the axial direction with respect to the front housing 21.

  The main inner clutch plate 32 has a plurality of engaging protrusions 321 that engage with the inner spline protrusion 231 of the inner shaft 23 with a backlash in the circumferential direction at the outer peripheral end. The main inner clutch plate 32 is restricted in relative rotation with the inner shaft 23 by the engagement protrusion 321 engaging with the inner spline protrusion 231 and is movable in the axial direction with respect to the inner shaft 23. The main inner clutch plate 32 has a plurality of oil holes 322 through which lubricating oil is circulated, which is formed on the inner side of the main outer clutch plate 31. A friction material formed using natural pulp or organic synthetic fiber as a base material is attached.

  The cam mechanism 4 is arranged between a pilot cam 41 as a first cam member, a main cam 42 as an annular second cam member arranged so as to be rotatable relative to the pilot cam 41, and between the pilot cam 41 and the main cam 42. And a plurality of cam balls 43 as spherical rolling members. The pilot cam 41 and the main cam 42 are both annular, and the inner shaft 23 is inserted through the center thereof. The main cam 42 is arranged in parallel with the pilot cam 41 in the axial direction. The main cam 42 is disposed on the main clutch 3 side, and the pilot cam 41 is disposed on the rear housing 22 side.

  The pilot cam 41 and the main cam 42 are made of a sintered body obtained by sintering metal powder such as iron. Here, sintering refers to a production method in which a metal powder as a raw material is put into a mold and compression molded, and the obtained molded body is baked and hardened in a sintering furnace. The main cam 42 is not limited to sintering, and may be formed by machining, for example.

  The pilot cam 41 is formed with a plurality of cam grooves 410 as first cam grooves on the surface facing the main cam 42. The main cam 42 is formed with the same number of cam grooves 420 as second cam grooves on the surface facing the pilot cam 41. The cam grooves 410 and 420 of the pilot cam 41 and the main cam 42 have a curved shape in which the radial cross-sectional shape shown in FIG. 2 has a curvature radius corresponding to the radius of the cam ball 43, and the axial depth of the cam grooves 410 and 420 is from the deepest portion. It is a circumferential groove that gradually becomes shallower as it is separated in the direction. The cam ball 43 can roll in the cam grooves 410 and 420 of the pilot cam 41 and the main cam 42 when the pilot cam 41 rotates relative to the main cam 42.

  The cam mechanism 4 moves the main clutch 42 in the axial direction with respect to the pilot cam 41 by the cam thrust generated by the cam balls 43 rolling on the cam grooves 410 and 420 of the pilot cam 41 and the main cam 42. 3 is pressed. Thereby, the main outer clutch plate 31 and the main inner clutch plate 32 are frictionally engaged, and the driving force is transmitted between the housing 20 and the inner shaft 23.

  The main cam 42 comes into contact with the main inner clutch plate 32 at one end of the main clutch 3 and presses the main clutch 3, and a cam provided on the inner peripheral side of the main cam 42 with respect to the pressing portion 421. The unit 422 is integrally formed. The cam groove 420 of the main cam 42 is provided on the axial end surface of the cam portion 422. In the main cam 42, a spline engaging portion 421a formed at the inner peripheral end of the pressing portion 421 is engaged with the inner spline protrusion 231 of the inner shaft 23, and relative rotation with the inner shaft 23 is restricted. The main cam 42 is biased so as to be separated from the main clutch 3 in the axial direction by a disc spring 44 disposed between the step surface 23 a formed on the inner shaft 23. For this reason, the cam ball 43 is positioned at the deepest portion of the cam grooves 410 and 420 in a non-operating state where no excitation current is supplied from the control device 10 to the driving force transmission device 2.

  The pilot cam 41 is provided on the inner diameter side of the cylindrical portion 411 with a spline engaging portion 411 a that receives a rotational force rotating relative to the main cam 42 from the electromagnetic clutch mechanism 5 on the outer peripheral surface. The cam portion 412 is integrally provided. The cam groove 410 of the pilot cam 41 is provided on the axial end surface of the cam portion 412.

  As shown in FIG. 3, a thrust roller bearing 45 and a shim 46 are disposed between the pilot cam 41 and the third annular member 223 of the rear housing 22. The thrust roller bearing 45 and the shim 46 are juxtaposed in the axial direction, and one of the side surfaces 46 a and 46 b of the shim 46 is in contact with the pilot cam 41. The thrust roller bearing 45 is disposed between the other side surface 46 b of the shim 46 and the axial end surface 223 a of the third annular member 223. In FIG. 3, the non-operating state of the driving force transmission device 2 is shown.

  The thrust roller bearing 45 regulates the axial movement of the pilot cam 41 with respect to the housing 20 and receives the reaction force of the cam thrust generated by the cam mechanism 4 via the shim 46. The thrust roller bearing 45 includes a plurality of needle rollers 451, a cage 452 that holds the plurality of needle rollers 451 in a rollable manner, and a race member 453 that latches the cage 452 in the axial direction. Yes. The race member 453 has a locking portion 453a that locks the retainer 452 at an end on the outer diameter side, a raceway surface 453b on which the needle rollers 451 roll, and an axial end surface 223a of the third annular member 223. And an abutting surface 453c that abuts on the.

  The plurality of needle rollers 451 roll on the raceway surface 453 b of the race member 453 and the side surface 46 b of the shim 46. In other words, a part of the side surface 46b of the shim 46 is formed as a raceway surface 46c on which the needle rollers 451 roll. In the radial direction orthogonal to the rotation axis O, the difference between the outer diameter and the inner diameter of the raceway surface 46c corresponds to the length of the needle roller 451 in the longitudinal direction. In the present embodiment, the plurality of needle rollers 451 are arranged at positions that are inside the center of the cam ball 43 in the radial direction perpendicular to the rotation axis O.

  The shim 46 adjusts an error in the distance between the pilot cam 41 and the rear housing 22 due to variations in the thickness of the main outer clutch plate 31 and the main inner clutch plate 32 of the main clutch 3. Based on the measurement results in the assembly process, a thickness is selected such that the distance between the side surface 46b of the shim 46 and the axial end surface 223a of the third annular member 223 is an appropriate value. The shim 46 has an annular plate shape, and its axial thickness is, for example, 1.0 to 2.2 mm.

  The electromagnetic clutch mechanism 5 includes an armature 50, a plurality of pilot outer clutch plates 51, a plurality of pilot inner clutch plates 52, and an electromagnetic coil 53. The electromagnetic clutch mechanism 5 functions as a rotational force applying mechanism that applies a rotational force that rotates the pilot cam 41 with respect to the main cam 42.

  The electromagnetic coil 53 is held by an annular yoke 530 made of a magnetic material and is accommodated in the accommodating space 22 a of the rear housing 22. The yoke 530 is supported by the third annular member 223 of the rear housing 22 by the ball bearing 63, and the outer peripheral surface thereof faces the inner peripheral surface of the first annular member 221. Further, the inner peripheral surface of the yoke 530 faces the outer peripheral surface of the third annular member 223. Excitation current is supplied to the electromagnetic coil 53 from the control device 10 via the electric wire 531.

  The plurality of pilot outer clutch plates 51 and the plurality of pilot inner clutch plates 52 are alternately arranged along the axial direction between the armature 50 and the rear housing 22. A plurality of arc-shaped slits for preventing a short circuit of magnetic flux generated by energization of the electromagnetic coil 53 are formed in the radial center of the pilot outer clutch plate 51 and the pilot inner clutch plate 52.

  The pilot outer clutch plate 51 has a plurality of engaging protrusions 511 that engage with the outer spline protrusions 211 of the front housing 21 at the outer peripheral end. The pilot inner clutch plate 52 has a plurality of engaging protrusions 521 that engage with the spline engaging portion 411a of the pilot cam 41 at the inner peripheral end portion.

  The armature 50 is an annular member made of a magnetic material such as iron, and a plurality of engagement protrusions 501 that engage with the outer spline protrusions 211 of the front housing 21 are formed on the outer peripheral portion. As a result, the armature 50 is movable in the axial direction with respect to the front housing 21, and relative rotation with respect to the front housing 21 is restricted.

  In the driving force transmission device 2 configured as described above, the armature 50 is attracted to the rear housing 22 side by the magnetic force generated when the exciting current is supplied to the electromagnetic coil 53, and the pilot outer clutch plate 51 and the pilot inner clutch The plate 52 is in frictional contact. Thereby, the rotational force of the housing 20 is transmitted to the pilot cam 41, the pilot cam 41 rotates relative to the main cam 42, and the cam ball 43 rolls in the cam grooves 410 and 420. As the cam ball 43 rolls, a cam thrust force that presses the main clutch 3 on the main cam 42 is generated, and a frictional force is generated between the plurality of main outer clutch plates 31 and the plurality of main inner clutch plates 32. The frictional force transmits a driving force between the housing 20 and the inner shaft 23. The driving force transmitted by the main clutch 3 increases or decreases according to the excitation current supplied to the electromagnetic coil 53.

(Main cam configuration)
FIG. 4A is a plan view showing an axial end surface 41 a on the main cam 42 side of the pilot cam 41. FIG. 4B is a plan view showing an axial end surface 41 b on the shim 46 side (opposite side of the main cam 42) of the pilot cam 41. FIG. 5 is a cross-sectional perspective view showing a cross section of the pilot cam 41 taken along line AA shown in FIG. 6A and 6B are a cross-sectional view of the pilot cam 41 shown in FIG. The cam ball 43 rolls in the cam groove 410 between the position on the AA line cross section and the position on the BB line cross section. Although not shown, the cam groove 420 of the main cam 42 is formed in the same manner as the cam groove 410 of the pilot cam 41.

  As shown in FIG. 4A, in the present embodiment, six cam grooves 410 are formed in the pilot cam 41, and the circumferential ends of these cam grooves 410 are continuous with each other. Corresponding to each of the six cam grooves 410, six cam balls 43 are arranged at equal intervals between the pilot cam 41 and the main cam 42. As shown in FIGS. 6A and 6B, the inner surface 410a of the cam groove 410 has an arcuate cross-sectional shape in the radial direction. In other words, a portion of the axial end surface 41 a of the pilot cam 41 that is recessed in an arc shape is the inner surface 410 a of the cam groove 410. In the present embodiment, the inner surface 410 a of the cam groove 410 in the radial section has an arc shape having a radius of curvature slightly larger than the radius of the cam ball 43.

  In FIG. 4A, the deepest portion 410b on the inner surface 410a of the cam groove 410 is indicated by a black circle. The deepest portion 410b is a portion having the deepest axial depth in the cam groove 410. More specifically, the deepest portion 410b is a portion farthest in the axial direction from a virtual plane including the center points of the plurality of cam balls 43. 4A, the center line 410c of the cam groove 410 extending in the circumferential direction of the pilot cam 41 is indicated by a one-dot chain line, and the radial line 410d including the deepest portion 410b and orthogonal to the center line 410c is indicated by a solid line. ing. In FIG. 4B, the outer edge of the cam groove 410 viewed from the axial end face 41b side is indicated by a broken line together with the center line 410c and the radial line 410d.

  Each cam groove 410 has a symmetrical shape with respect to the radial line 410d, and the depth in the axial direction becomes shallower as the distance from the radial line 410d in the circumferential direction increases. The cam ball 43 may contact the inner surface 410a of the cam groove 410 at one point on the center line 410c, or may contact (angular contact) the inner surface 410a of the cam groove 410 at two points sandwiching the center line 410c. .

The pilot cam 41, at least a portion of the axial end face 41b corresponding to the back side of the cam groove 410 is formed as the output surface 41b ₁ for outputting a reaction force of the cam thrust. Hereinafter, among the axial end face 41b of the pilot cam 41, a portion not included in the output surface 41b ₁ of the non-output surface 41b _2. The output surface 41b ₁ protrudes from the non-output surface 41b _{2 in the} axial direction, and a step surface 41b ₃ is formed between the output surface 41b ₁ and the non-output surface 41b ₂ .

In this embodiment, the output surface 41b ₁ and a non-output surface 41b ₂ are made of a sintered skin. Here, the sintered skin refers to a so-called black skin surface, which is a surface skin that has been sintered, that is, a rough surface skin that has not been flattened by grinding or the like.

In the present embodiment, the output surface 41 b ₁ of the pilot cam 41 contacts the _one side surface 46 a of the shim 46. The thrust roller bearing 45 indirectly receives the reaction force of the cam thrust output from the output surface 41 b ₁ of the pilot cam 41 via the shim 46. However, when the thrust roller bearing 45 has a pair of race members and a plurality of needle rollers are arranged between the pair of race members, the shim 46 is not used and the pair of race members is used. may abut the other side of the race member to the output surface 41b ₁ of the pilot cam 41 and the rear housing 22 side. In this case, the thrust roller bearing 45 is directly subjected to the reaction force of the cam thrust from the output surface 41b ₁ of the pilot cam 41.

Output surface 41b ₁ of the pilot cam 41 is preferably a plane orthogonal to the axial direction. If there is a bulge portion protruding axially on a part of the output surface 41b ₁ of the pilot cam 41, for example, non-uniformity is increased in the longitudinal direction of the load which the needle rollers 451 of the thrust roller bearing 45 is subjected, needle rollers This is because local flaking or wear tends to occur in 451. That is, the reaction force of the cam thrust is intensively output from the bulging portion to the thrust roller bearing 45 side, and flaking and wear occur at a position where the needle roller 451 is aligned with the bulging portion in the axial direction. It becomes easy.

  By the way, since a sintered body is generally manufactured by baking and compacting a molded body made of compression-molded metal powder as described above, if there is a portion with a different thickness, the density of the metal powder and the thickness at the time of consolidation are thick. Distortion may occur due to a difference in shrinkage between the portion and the thin portion. For example, in the case of a sintered body in which a groove with a gradually changing depth is formed on one of the end surfaces in the axial direction, such as a cam member of a ball cam mechanism, the portion corresponding to the back side of the deep portion of the groove is in a state after compression molding. It has been confirmed by the present inventors that it is easier to bulge.

Therefore, the axial end surface 41b of the pilot cam 41 according to the present embodiment is surrounded by a region including at least a part of the portion corresponding to the back side of the deepest portion 410b of the cam groove 410 and the outer diameter side and the inner diameter side of the portion. is formed to be recessed in the axial direction than the region near the direction, the recessed by being formed region is formed so as not to include in the output surface 41b _1. Hereinafter, on the axial end surface 41b of the pilot cam 41, a portion corresponding to the back side of the deepest portion 410b is referred to as a deepest portion corresponding portion, and is denoted by reference numeral 41c in FIG. Further, the portion corresponding to the outer diameter side of the deepest portion corresponding portion 41c on the back side of the cam groove 410 is referred to as the deepest portion corresponding outer diameter side portion, and is denoted by reference numeral 41d. Further, a portion on the back side of the cam groove 410 and corresponding to the inner diameter side of the deepest portion corresponding portion 41c is referred to as a deepest portion corresponding inner diameter side portion, and is denoted by reference numeral 41e. Furthermore, the area | region which corresponds to the back side of the cam groove 410 among the axial direction end surfaces 41b is called a cam groove back surface area | region, and is shown by the code | symbol 41f.

  The cam groove back surface region 41f is a region that overlaps the inner surface 410a of the cam groove 410 when the pilot cam 41 is viewed in the axial direction. In the present embodiment, as described above, since the circumferential ends of the plurality of cam grooves 410 are continuous with each other, the inner surface 410a of the cam groove 410 rotates between the outer edge line 410e and the inner edge line 410f. The cam groove back surface region 41f is also an annular region centered on the rotation axis O.

In the present embodiment, a region including at least a part of the deepest portion corresponding outer diameter side portion 41d which is a portion on the outer diameter side than the deepest portion corresponding portion 41c is recessed in the axial direction from the peripheral region in the circumferential direction. Is formed. Hereinafter, the region formed by the depression is referred to as a depression, and is denoted by reference numeral 41g in FIG. Moreover, the vicinity area | region of the circumferential direction of the recessed part 41g is shown with the code | symbol 41h. Neighboring region 41h is included in the output surface 41b _1. Recess 41g is included in the non-output surface 41b ₂ in the cam groove back surface region 41f. Meanwhile, the deepest portion corresponding inside diameter side portion 41e in its entirety is included in the output surface 41b _1.

When viewed axial end face 41b of the pilot cam 41 in the axial direction, the outer edge line 41i of the output surface 41b _1, as shown in FIG. 4 (b), six straight portions 41i ₁ and six arcuate section 41i ₂ Become. The straight line portion 41i ₁ is a straight line that is orthogonal to the radial line 410d and includes the deepest portion corresponding portion 41c. The arc portion 41 i ₂ has an arc shape extending over a predetermined angular range in the circumferential direction across the shallowest portion of the cam groove 410. The entire outer edge line 41i is included in the cam groove back surface region 41f. With this configuration, the outer edge line 41 i has an outer diameter that overlaps with the radial line 410 d as viewed in the axial direction smaller than an outer diameter of the part that overlaps the circumferential end of the cam groove 410.

Further, in FIG. 4 (b), it shows six virtual circle line 41i ₀ respectively connecting between the rotation axis O 6 an arc portion 41i around the ₂ by a two-dot chain line. Recess 41g is formed between the straight portion 41i ₁ and the virtual arcuate line 41i _0. Neighboring region 41h is the inner region corresponding circumferential ends of the arcuate portion 41i _2.

The length of the straight portion 41 i ₁ between the _two arc portions 41 i ₂ is longer than the diameter of the cam ball 43. Thereby, in this embodiment, at least a part of the outer diameter side of the deepest portion corresponding portion 41 c included in the cam groove back surface region 41 f is not included in the output surface 41 b ₁ over a circumferential width equal to or larger than the diameter of the cam ball 43. A pilot cam 41 is configured. In other words, the recess 41 g is formed over a circumferential width equal to or larger than the diameter of the cam ball 43.

Further, in the present embodiment, as described above, since the plurality of needle rollers 451 are arranged at positions inside the center of the cam ball 43, the cam mechanism 4, the thrust roller bearing 45, and the shim 46 are pivoted. when viewed in the direction, the entire raceway surface 46c of the shim 46 that needle rollers 451 roll overlaps the output surface 41b ₁ and the axial direction of the pilot cam 41. Thereby, the load received by the needle rollers 451 by the reaction force of the cam thrust is equalized in the longitudinal direction of the needle rollers 451.

(Operation and effect of the first embodiment)
Next, the operation and effect of the present embodiment will be described by comparison with a comparative example.

  FIG. 7 is a radial cross-sectional view showing a pilot cam 41A according to a comparative example. The pilot cam 41A is formed in the same manner as the pilot cam 41 according to the present embodiment except that the recess 41g is not provided. Of the constituent elements of the pilot cam 41A, portions common to the pilot cam 41 are denoted by the same reference numerals as those shown in FIG. 7A is a cross-sectional view corresponding to the AA cross section of the pilot cam 41 shown in FIG. 4B, and FIG. 7B is a BB cross section of the pilot cam 41 shown in FIG. 4B. It is sectional drawing corresponding to.

The pilot cam 41A, since the recess 41g is not provided, the outer edge of the output surface 41b ₁ is circular. When the pilot cam 41A having such a configuration is formed by sintering, it has been confirmed by the present inventors that a bulging portion 41j is generated in the deepest portion corresponding outer diameter side portion 41d. The bulging portion 41j protrudes in the axial direction than the virtual plane V including an output surface 41b ₁ of the portion other than the bulged portion 41j (Figure 7 (a) shows a two-dot chain line).

When such bulging portion 41j is generated at the output surface 41b _1, the reaction force of the cam thrust is outputted centrally from bulging portion 41j, one end portion in the longitudinal direction of the needle rollers 451 of the thrust roller bearing 45 The load at is increased. For this reason, flaking and local wear are likely to occur in the needle rollers 451 at the one end.

On the other hand, in the pilot cam 41 according to the present embodiment, since the recessed portion 41g is provided in the portion where the bulging portion 41j is generated in the pilot cam 41A, the output surface 41b ₁ Is formed on a flat surface having no projection perpendicular to the axial direction. Therefore, without reaction force of the cam thrust is outputted intensively to a portion, the surface pressure of the output surface 41b ₁ when the cam mechanism 4 is actuated is equalized, flaking Ya the needle rollers 451 The occurrence of local wear is suppressed. Further, when the recessed portion 41g is not provided like the pilot cam 41A, the bulging portion 41j is generated over a wider range as the diameter of the cam ball 43 is larger. However, in the present embodiment, since the recess 41g is formed over the circumferential width that is equal to or larger than the diameter of the cam ball 43, the occurrence of the bulging portion 41j is reliably suppressed.

[Second Embodiment]
Next, a pilot cam 41B according to a second embodiment of the present invention will be described with reference to FIGS. The pilot cam 41B made of this sintered body constitutes the cam mechanism 4 together with the main cam 42 and the plurality of cam balls 43 according to the first embodiment, and is incorporated in the driving force transmission device 2. Hereinafter, the difference between the pilot cam 41B and the first embodiment will be mainly described.

  FIG. 8A is a plan view showing an axial end surface 41 a on the main cam 42 side of the pilot cam 41. FIG. 8B is a plan view showing the axial end surface 41 b on the shim 46 side of the pilot cam 41. FIG. 9 is a cross-sectional perspective view showing a cross section along line CC shown in FIG. 8B of the pilot cam 41B. In FIG. 8 and FIG. 9, the same components as those described for the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

In the first embodiment, recesses 41g is provided in a region including a part of the deepest portion corresponding radially outer portion 41d, it has been described a case where this area is not included in the output surface 41b _1. In the present embodiment, of the axial end surface 41b of the pilot cam 41B, the deepest portion corresponding portion 41c and the deepest portion corresponding outer diameter side portion 41d and the deepest portion corresponding inner diameter side portion 41e, which are regions on the inner diameter side and the outer diameter side thereof. but not included in the output surface 41b _1. More specifically, it extends recess 41g which is formed to be recessed in the axial direction in the radial direction of the pilot cam 41B than the circumferential direction of the neighboring region 41h, the output surface 41b ₁ by the recess portion 41g is divided Yes. In this embodiment, the output surface 41b ₁ by six recess 41g is divided into six. Output surface 41b ₁ is a flat surface formed on the end surface of the protrusions formed on the land like the axial end face 41b of the pilot cam 41B.

The axial end face 41b of the recess 41g is included in the non-output surface 41b _2. Further, in the circumferential direction of the pilot cam 41B, the end portion of the recess portion 41g side of the output surface 41b ₁ corresponds to the region near 41h. Each output surface 41b ₁ is a fan-shaped as viewed in the axial direction, the outer line 41k includes a outer circumferential arc 41k ₁ and the inner circumferential arc portion 41k _2, the outer circumferential arc 41k ₁ and the inner circumferential arc portions between 41k ₂ a pair of linear portions 41k ₃ Metropolitan between both the ends. Recess 41g is provided between the respective straight portions 41k ₃ in the pair of output surface 41b ₁ adjacent to each other in the circumferential direction. Recess facing through 41g these straight portions 41k ₃ are parallel to each other.

(Operation and effect of the second embodiment)
According to the present embodiment, the same operations and effects as the operations and effects described in the first embodiment can be obtained. Further, in the present embodiment, among the axial end face 41b of the pilot cam 41B, the deepest portion corresponding site 41c, the deepest corresponding radially outer portion 41d, and the deepest portion corresponding inside diameter side portion 41e is included in the output surface 41b ₁ not because it is suppressed bulging portion is generated in the output surface 41b ₁ more reliably.

Note that by recess 41g is formed to extend in the radial direction of the pilot cam 41B, the entire periphery of the deepest portion corresponding site 41c becomes non-output surface 41b _2, the deepest portion 410b of the cam groove 410 When the cam ball 43 is positioned near the neutral position of the cam mechanism 4, a large cam thrust and its reaction force are not generated. For this reason, even if the recess 41g is formed over the deepest part corresponding part 41c, the deepest part corresponding outer diameter side part 41d, and the deepest part corresponding inner diameter side part 41e, the pilot cam 41B and the shim 46 are caused by the reaction force of the cam thrust. There is no significant deformation.

(Appendix)
As mentioned above, although this invention was demonstrated based on 1st and 2nd embodiment, these embodiment does not limit the invention which concerns on a claim. In addition, it should be noted that not all the combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

  Further, the present invention can be appropriately modified and implemented without departing from the spirit of the present invention. For example, in the above embodiment, the case where the cam mechanism 4 is applied to the driving force transmission device 2 has been described. However, the present invention is not limited to this, and the present invention can be applied to various devices that operate by converting rotational force into axial cam thrust. It is possible to apply the cam mechanism of the invention.

2 ... Driving force transmission device 20 ... Housing (first rotating member)
23 ... Inner shaft (second rotating member)
3 ... Main clutch (multi-plate clutch)
31 ... Main outer clutch plate (first friction plate)
32 ... Main inner clutch plate (second friction plate)
41, 41B ... pilot cam (first cam member)
410: Cam groove (first cam groove)
410a ... inner surface 410b ... deepest part 41b ... axial end face 41b ₁ ... output face 41c ... deepest part corresponding part (part corresponding to the back side of the deepest part)
41d ... outer diameter side part corresponding to the deepest part (part corresponding to the outer diameter side of the deepest part corresponding part)
41e ... inner diameter side portion corresponding to deepest portion (portion corresponding to inner diameter side of deepest portion corresponding portion)
41f: Cam groove back surface area (area corresponding to the back side of the cam groove)
41 g ... depression (area formed by depression)
41h ... Near region 42 ... Main cam (second cam member)
420 ... Cam groove (second cam groove)
43. Cam ball (rolling member)
45 ... Cam mechanism 5 ... Electromagnetic clutch mechanism (rotational force applying mechanism)

Claims (6)

A first cam member made of a sintered body formed in an annular shape, an annular second cam member arranged in parallel in the axial direction so as to be relatively rotatable with the first cam member, and a first cam member formed on the first cam member A spherical rolling member capable of rolling the first cam groove and the second cam groove formed in the second cam member, and the rolling member rolls the first cam groove and the second cam groove; A cam mechanism in which the second cam member moves in the axial direction with respect to the first cam member by a cam thrust generated by
The first cam groove and the second cam groove have a curved shape in which a radial cross-sectional shape has a curvature radius corresponding to a radius of the rolling member, and an axial depth is spaced from the deepest portion in the circumferential direction. Are circumferential grooves that gradually become shallower,
The first cam member is formed as an output surface made of a sintered skin in which a part of an axial end surface opposite to the second cam member outputs a reaction force of the cam thrust,
The axial end surface of the first cam member includes a region that includes at least a part of a portion corresponding to the back side of the deepest portion of the first cam groove and a portion corresponding to the outer diameter side and the inner diameter side of the portion. Is formed in a more hollow in the axial direction, the region formed in the depression is not included in the output surface,
Cam mechanism. The region formed by depression includes at least a part of a portion on the outer diameter side of the portion corresponding to the back side of the deepest portion of the first cam groove.
The cam mechanism according to claim 1. Of the axial end face of the first cam member, at least a part of the region corresponding to the outer diameter side of the portion corresponding to the back side of the deepest portion of the first cam groove and the back side of the first cam groove is Not included in the output surface over a circumferential width equal to or greater than the diameter of the spherical member;
The cam mechanism according to claim 2. Of the end face in the axial direction of the first cam member, regions on the inner diameter side and outer diameter side of the portion corresponding to the back side of the deepest portion of the first cam groove are not included in the output surface.
The cam mechanism according to claim 2. The cam mechanism according to any one of claims 1 to 4,
A first rotating member and a second rotating member arranged so as to be relatively rotatable on the same axis;
A first friction plate in which relative rotation with the first rotation member is restricted; and a multi-plate clutch having a second friction plate in which relative rotation with the second rotation member is restricted;
A rotational force applying mechanism for applying a rotational force for rotating the first cam member relative to the second cam member;
The first cam member is disposed between the axial end surface and the first rotating member, restricts axial movement of the first cam member relative to the first rotating member, and is output from the output surface. A thrust roller bearing that receives a reaction force of the cam thrust,
When the second cam member moves in the axial direction with respect to the first cam member, the first friction plate and the second friction plate of the multi-plate clutch are frictionally engaged, and the first rotating member and A driving force is transmitted to and from the second rotating member.
Driving force transmission device. The thrust roller bearing includes a plurality of needle rollers that are rotatably held by a cage, and the entire raceway surface on which the needle rollers roll overlaps the output surface in the axial direction.
The driving force transmission device according to claim 6.

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