JP2013087834A - Driving power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving power transmission device in which the rapid change of transmission torque can be suppressed when employing a cam mechanism including two stages of cam parts.SOLUTION: A cam mechanism 150 includes: a support cam member 151; a movable cam member 152, a cam ball 153; and a first elastic member 154 and a second elastic member 155 which energize the movable cam member 152 to an inner shaft 120 or a main clutch 130 in an axial direction opposed to the side of the main clutch 130. In the case where the cam ball 153 is positioned at a deeper side than a predetermined position of first cam parts 151a1-152b1, the first elastic member 154 generates energizing force, and the second elastic member 155 does not generate any energizing force. In the case where the cam ball 153 is positioned at a shallower side than the predetermined position of the first cam parts 151a1-152b1 and the cam ball 153 is positioned in second cam parts 151a2-152b2, the first electric member 154 and the second elastic member 155 generate energizing force.

Description

  The present invention relates to a driving force transmission device having a two-stage cam portion in a cam mechanism that generates an axial force.

  A driving force transmission device referred to as a so-called electronically controlled coupling is disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-108575 (Patent Document 1). This driving force transmission device is configured as follows. Torque corresponding to the rotation difference between the outer rotating member and the inner rotating member is transmitted to the cam mechanism via the pilot clutch of the electromagnetic clutch device, and the torque is converted into an axial pressing force against the main clutch by the cam mechanism and pressed. Torque is transmitted between the outer rotating member and the inner rotating member by the main clutch.

  This cam mechanism forms a two-stage cam portion by a support-side cam groove formed in the support cam member and a moving-side cam groove formed in the moving cam member. That is, the first cam portion having a large inclination angle and the second cam portion having an inclination angle smaller than the inclination angle of the first cam portion are continuously formed.

Japanese Patent Laid-Open No. 2004-108575

  However, at the moment when the cam ball moves at the boundary between the first cam portion and the second cam portion, the force pressing the main clutch by the moving cam member changes suddenly. That is, the torque transmitted between the outer rotating member and the inner rotating member changes suddenly before and after the instant. The sudden change in the transmission torque is uncomfortable for the driver.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a driving force transmission device that can suppress a sudden change in transmission torque when a cam mechanism having a two-stage cam portion is employed. To do.

  (Claim 1) A driving force transmission device according to the present invention includes a cylindrical outer rotating member, an axial inner rotating member coaxially disposed in the outer rotating member so as to be relatively rotatable, and the outer rotating member. An electromagnetic clutch device including a main clutch for transmitting torque between a member and the inner rotating member; a pilot clutch capable of transmitting the torque of the outer rotating member by attracting an armature by a magnetic force; and the main clutch and the pilot A phase difference between the rotation of the outer rotating member and the rotation of the inner rotating member, which is provided between the clutch and transmitted via the pilot clutch, is converted into an axial pressing force to move the moving cam member to the shaft. And a cam mechanism that presses the main clutch by moving in the direction.

  The cam mechanism includes a support cam member that is spline-fitted to the pilot clutch and includes a support-side cam groove, the movable cam member that is spline-fitted to the inner rotation member and includes a moving-side cam groove, and the support side A cam ball interposed between the cam groove and the moving cam groove and moving the moving cam member with respect to the support cam member; and the moving cam member with respect to the inner rotating member or the main clutch. A first elastic member and a second elastic member that are urged in an axial direction opposite to the clutch side are provided.

  The support-side cam groove and the moving-side cam groove are formed with a first cam portion whose angle with respect to the axis perpendicular to the axis is a first angle, shallower than the first cam portion, and adjacent to the first cam portion in the circumferential direction. And a second cam portion having a second angle smaller than the first angle with respect to the axis perpendicular to the axis. When the cam ball is positioned deeper than a predetermined position of the first cam portion, the first elastic member generates a biasing force, and the second elastic member does not generate a biasing force, and the cam ball Is located on a side shallower than a predetermined position of the first cam portion, and when the cam ball is located on the second cam portion, the first elastic member and the second elastic member generate a biasing force. .

  (Claim 2) The spring constant of the second elastic member may be set larger than the spring constant of the first elastic member.

  (Claim 3) The main clutch is sandwiched between a plurality of outer clutch plates that are spline fitted to the outer rotating member and a plurality of outer clutch plates that are spline fitted to the inner rotating member. The inner clutch plate is disposed radially inward from the inner circumferential surface of the outer clutch plate, and is sandwiched between inner clutch plates at both ends of the plurality of inner clutch plates, and receives a biasing force from the second elastic member. Thus, an inner clutch restricting member that restricts the approach of the inner clutch plates at both ends may be provided.

  (Claim 4) Further, the second elastic member is interposed between the main clutch and the moving cam member in an axial direction, and the moving cam is located on a side opposite to the main clutch side with respect to the main clutch. A disc spring urging in the axial direction, and the driving force transmitting device is interposed between the main clutch and the moving cam member in the axial direction to transmit a pressing force applied to the main clutch by the moving cam member. A disc spring deformation restricting member that restricts the amount of axial deformation of the disc spring may be provided.

  (Claim 1) According to the present invention, the cam mechanism forms a two-stage cam portion. That is, the cam mechanism configures a first cam portion whose angle with respect to the axis orthogonal plane is a first angle and a second cam portion whose angle with respect to the axis orthogonal plane is a second angle smaller than the first angle. With the first cam portion having a large inclination angle, the amount of axial movement of the movable cam member relative to the support cam member can be increased. Furthermore, a large pressing force against the main clutch can be obtained by the second cam portion having a small inclination angle.

  And when a cam ball is located in the side deeper than the predetermined position of the 1st cam part, the 1st elastic member has generated energizing force. Therefore, the movable cam member can be reliably moved to a position far from the main clutch by the first elastic member. That is, since the engagement of the main clutch can be reliably released by the action of the first cam portion and the first elastic member, the drag torque can be reduced.

  Furthermore, the first elastic member and the second elastic member generate a biasing force when the cam ball is positioned on a shallower side than the predetermined position of the first cam portion and when the cam ball is positioned on the second cam portion. That is, the first elastic member and the second elastic member generate an urging force before and after the boundary between the first cam portion and the second cam portion of the cam ball. Therefore, the urging force to the side opposite to the main clutch received by the moving cam member is increased. Here, when the cam ball moves around the boundary between the first cam portion and the second cam portion, the pressing force of the moving cam member against the main clutch changes. However, since the urging force of the second elastic member is generated in addition to the first elastic member at this moment, it is possible to suppress a sudden change in the pressing force to the main clutch by the moving cam member. As a result, a sudden change in the transmission torque of the main clutch can be suppressed, and the driver's discomfort can be alleviated.

  (Claim 2) By making the spring constant of the second elastic member larger than the spring constant of the first elastic member, the moving cam member is pressed against the main clutch before and after the boundary between the first cam portion and the second cam portion. A sudden change in force can be suppressed more reliably.

  (Claim 3) An axial gap is formed between the opposing surfaces of the adjacent inner clutch plates and radially inward from the inner peripheral surface of the outer clutch plate. When the position where the second elastic member urges the inner clutch plate is located radially inward from the inner peripheral surface of the outer clutch plate, the portion of the inner clutch plate in which the axial gap is formed is It will be pressed in the axial direction. As a result, the inner clutch plate may be deformed. However, by providing the inner clutch restricting member, it is possible to restrict the approach between the inner clutch plates at both ends, so that deformation of the inner clutch plate can be suppressed. Therefore, the urging force by the second elastic member can be reliably transmitted to the inner clutch plate.

  (Claim 4) When the disc spring as the second elastic member is deformed into a completely collapsed state, there is a possibility that the shape is reversed. Inversion may affect the durability and spring constant of the disc spring. However, by providing the disc spring deformation restricting member, it is possible to prevent the disc spring from being inverted. Further, the disc spring deformation restricting member transmits the pressing force of the moving cam member to the main clutch. That is, it is possible to restrict the deformation of the disc spring using a member for transmitting the pressing force from the moving cam member to the main clutch.

It is a skeleton figure which shows a part of drive system of a vehicle provided with the driving force transmission apparatus of this embodiment. FIG. 2 is an axial sectional view of the driving force transmission device of FIG. 1, showing a state in which the moving cam member does not generate a pressing force against the main clutch. It is the fragmentary view seen from the left side of the support cam member in FIG. It is the fragmentary view seen from the right side of the movement cam member in FIG. FIG. 14 is a circumferential cross-sectional view of the support-side cam groove and the moving-side cam groove of the cam mechanism in FIG. 2 and shows the state of the phase difference θ0 in FIGS. FIG. 14 is a sectional view in the circumferential direction of the cam mechanism in FIG. 2 and shows a state of the phase difference θ1 in FIGS. FIG. 14 is a cross-sectional view of the cam mechanism in FIG. 2 in the circumferential direction, showing the state of the phase difference θ2 in FIGS. FIG. 14 is a sectional view in the circumferential direction of the cam mechanism in FIG. 2 and shows a state of the phase difference θ3 in FIGS. FIG. 3 shows a state in which the moving cam member generates a pressing force against the main clutch with respect to the driving force transmission device of FIG. 2. It is a figure which shows the amount of axial displacement of a movement cam member with respect to the phase difference of a support cam member and a movement cam member. It is a figure which shows the urging | biasing force by the 1st, 2nd elastic member with respect to the phase difference of a support cam member and a movement cam member. It is a figure which shows the axial direction force of the movement cam member with respect to the phase difference of a support cam member and a movement cam member. It is a figure which shows the transmission torque of the main clutch with respect to the phase difference of a support cam member and a movement cam member.

  The driving force transmission device of this embodiment will be described. The driving force transmission device of this embodiment is applied as a device for switching between a four-wheel drive mode and a two-wheel drive mode of an automobile. Therefore, a case where the driving force transmission device is applied to a four-wheeled vehicle will be described as an example.

(Automotive drive system)
A part of the drive system of the automobile will be described with reference to FIG. Here, the vehicle can switch between a front wheel driving mode in which the driving force of the engine is transmitted only to the front wheels and a four-wheel driving mode in which the driving force is transmitted to the front and rear wheels. FIG. 1 shows a driving force transmission system from an engine (not shown) to the rear wheels.

  As shown in FIG. 1, a driving force from an engine (not shown) is transmitted to the rear wheel differential device 20 via the propeller shaft 10. The rear wheel differential device 20 includes a drive pinion 21, a ring gear 22, pinions 23 and 24, and side gears 25 and 26. Then, the driving force transmitted from the propeller shaft 10 to the drive pinion 21 of the rear wheel differential 20 is transmitted to the left rear wheel drive shaft 31 via the pinions 23 and 24 and the side gear 25, and is transmitted to the left rear wheel 36. Communicated. On the other hand, the driving force transmitted to the drive pinion 21 is transmitted to the right rear wheel output shaft 32 via the pinions 23 and 24 and the side gear 26. The right rear wheel output shaft 32 is transmitted to the right rear wheel 37 via the driving force transmission device 100 and the right rear wheel drive shaft 33.

  Here, the driving force transmission device 100 has a connection state in which torque is transmitted between the input-side right rear wheel output shaft 32 and the output-side right rear wheel drive shaft 33, and a disconnected state in which torque transmission is not performed. Switch. That is, in the four-wheel drive mode, the driving force transmission device 100 is switched to the connected state, and the driving force from the engine is transmitted to the left and right rear wheels 36 and 37. On the other hand, when the front wheel drive mode is set, the driving force transmission device 100 is switched to the disconnected state, and the left and right rear wheels 36 and 37 are in a free state. At this time, the left and right rear wheels 36 and 37 are driven by contact with the road surface.

  In the four-wheel drive mode, when the driving force transmission device 100 is in the connected state, the right rear wheel output shaft 32 that is the input side of the driving force transmission device 100 and the right rear wheel drive shaft 33 that is the output side. And rotate in the same direction. On the other hand, in the front wheel drive mode, when the driving force transmission device 100 is disconnected, the right rear wheel output shaft 32 that is the input side of the driving force transmission device 100 and the right rear wheel drive shaft 33 that is the output side Rotates in the opposite direction. Thus, since the input / output rotation direction is reversed by switching the mode, it is necessary to make the drag torque very small when the driving force transmission device 100 is in the disconnected state.

(Configuration of driving force transmission device)
The configuration of the driving force transmission device 100 will be described with reference to FIG. The driving force transmission device 100 includes a so-called electronic control coupling. As shown in FIG. 2, the driving force transmission device 100 includes an outer case 110 as an outer rotating member, an inner shaft 120 as an inner rotating member, a main clutch 130, and an electromagnetic clutch device 140 constituting a pilot clutch mechanism. And a cam mechanism 150.

  The outer case 110 is supported on the inner peripheral side of a cylindrical hole cover (not shown) so as to be rotatable with respect to the hole cover. The outer case 110 is formed in a cylindrical shape as a whole, and is formed by a front housing 111 disposed on the left side of the vehicle (left side in FIG. 2) and a rear housing 112 disposed on the right side of the vehicle (right side in FIG. 2). Has been.

  The front housing 111 is made of, for example, an aluminum alloy made of a nonmagnetic material containing aluminum as a main component, and has a bottomed cylindrical shape. The outer peripheral surface of the cylindrical portion of the front housing 111 is rotatably supported on the inner peripheral surface of the hole cover via a bearing. Further, the bottom of the front housing 111 is connected to the right rear wheel output shaft 32 (shown in FIG. 1). That is, the bottomed cylindrical opening side of the front housing 111 is disposed so as to face the right side of FIG. A female spline 111a is formed at the axially central portion of the inner peripheral surface of the front housing 111, and a female screw is formed near the opening of the inner peripheral surface.

  The rear housing 112 is formed in an annular shape, and is disposed integrally with the front housing 111 on the radially inner side of the opening side of the front housing 111. On the right side of the rear housing 112 in FIG. 2, an annular groove is formed over the entire circumference. A part of the bottom of the annular groove of the rear housing 112 is provided with an annular member 112a formed of, for example, stainless steel as a nonmagnetic material. Parts of the rear housing 112 other than the annular member 112a are formed of a material mainly composed of iron, which is a magnetic material, to form a magnetic circuit (hereinafter referred to as “iron-based material”). A male screw is formed on the outer peripheral surface of the rear housing 112, and the male screw is fastened and fixed to the female screw of the front housing 111.

  The inner shaft 120 is formed in an axial shape including a male spline 120a at the axially central portion of the outer peripheral surface. The inner shaft 120 passes through a central through hole of the rear housing 112 in a liquid-tight manner, and is coaxially disposed in the outer case 110 so as to be relatively rotatable. The inner shaft 120 is rotatably supported by the front housing 111 and the rear housing 112 via bearings in a state where the axial position is restricted with respect to the front housing 111 and the rear housing 112. Further, the vehicle right side (the right side in FIG. 2) of the inner shaft 120 is connected to the right rear wheel drive shaft 33 (shown in FIG. 1). The space that is liquid-tightly partitioned by the outer case 110 and the inner shaft 120 is filled with lubricating oil at a predetermined filling rate.

  The main clutch 130 transmits torque between the outer case 110 and the inner shaft 120. The main clutch 130 is a wet multi-plate friction clutch formed of an iron-based material. The main clutch 130 is disposed between the inner peripheral surface of the cylindrical portion of the front housing 111 and the outer peripheral surface of the inner shaft 120. The main clutch 130 is disposed between the bottom of the front housing 111 and the left end surface of the rear housing 112 in FIG. The main clutch 130 includes an inner main clutch plate 131 and an outer main clutch plate 132, and is alternately arranged in the axial direction. That is, each inner main clutch plate 131 is disposed between each of the plurality of outer main clutch plates 132.

  The inner main clutch plate 131 has a female spline 131 a formed on the inner peripheral side, and is fitted to the male spline 120 a of the inner shaft 120. The outer main clutch plate 132 has a male spline 132 a formed on the outer peripheral side, and is fitted to the female spline 111 a of the front housing 111.

  Further, in addition to both ends of the plurality of inner main clutch plates 131, a plurality of through holes 131b are formed between the inner peripheral edge and the outer peripheral edge so as to be in phase with each other. The portion where the through hole 131 b is formed is located radially inward from the inner peripheral surface of the outer main clutch plate 132.

  The main clutch 130 further includes a restriction pin 133 as an inner clutch restriction member. The restriction pin 133 is inserted through the through hole 131b of the inner main clutch plate 131 other than both ends, and is sandwiched between the inner main clutch plates 131 at both ends. And the approach of the inner main clutch board 131 of both ends is controlled because the both end surfaces of the regulation pin 133 contact | abut to the inner main clutch board 131 of both ends. Here, in a state where both end surfaces of the regulation pin 133 are in contact with the inner main clutch plates 131 at both ends, sufficient torque transmission can be performed between the plurality of inner main clutch plates 131 and the outer main clutch plates 132. As described above, the length of the regulation pin 133 is set. Further, the inner main clutch plates 131 at both ends are formed thicker than others. That is, the inner main clutch plates 131 at both ends can suppress deformation due to being pressed against the regulation pin 133.

  The electromagnetic clutch device 140 engages the pilot clutches 144 by pulling the armature 143 toward the yoke 141 by magnetic force. That is, the electromagnetic clutch device 140 transmits the torque of the outer case 110 to the support cam member 151 constituting the cam mechanism 150. The electromagnetic clutch device 140 includes a yoke 141, an electromagnetic coil 142, an armature 143, and a pilot clutch 144.

  The yoke 141 is formed in an annular shape, and is accommodated in an annular groove of the rear housing 112 through a gap so as to be rotatable relative to the rear housing 112. The yoke 141 is fixed to the hole cover. Further, the inner peripheral side of the yoke 141 is rotatably supported by the rear housing 112 via a bearing. The electromagnetic coil 142 is formed in an annular shape by winding a winding, and is fixed to the yoke 141.

  The armature 143 is made of an iron-based material. It is formed in an annular shape having a male spline on the outer peripheral side. The armature 143 is disposed between the main clutch 130 and the rear housing 112 in the axial direction. The outer peripheral side of the armature 143 is fitted to the female spline 111a of the front housing 111. The armature 143 acts so as to be drawn toward the yoke 141 when a current is supplied to the electromagnetic coil 142.

  The pilot clutch 144 transmits torque between the outer case 110 and the support cam member 151. The pilot clutch 144 is made of an iron-based material. The pilot clutch 144 is disposed between the inner peripheral surface of the cylindrical portion of the front housing 111 and the outer peripheral surface of the support cam member 151. Further, the pilot clutch 144 is disposed between the armature 143 and the left end surface of the rear housing 112 in FIG. The pilot clutch 144 includes an inner pilot clutch plate 144a and an outer pilot clutch plate 144b, and is alternately arranged in the axial direction. The inner pilot clutch plate 144 a has a female spline formed on the inner peripheral side, and is fitted to the male spline of the support cam member 151. The outer pilot clutch plate 144 b has a male spline formed on the outer peripheral side, and is fitted to the female spline 111 a of the front housing 111.

  When a current is supplied to the electromagnetic coil 142, a magnetic circuit passing through the yoke 141, the outer peripheral side of the rear housing 112, the pilot clutch 144, the armature 143, the pilot clutch 144, the inner peripheral side of the rear housing 112, and the yoke 141 is generated. It is formed. Then, the armature 143 is drawn toward the yoke 141 side, and the inner pilot clutch plate 144a and the outer pilot clutch plate 144b are frictionally engaged. Then, the torque of the outer case 110 is transmitted to the support cam member 151. On the other hand, when the current supply to the electromagnetic coil 142 is cut off, the attractive force to the armature 143 is lost, and the frictional engagement force between the inner pilot clutch plate 144a and the outer pilot clutch plate 144b is released.

  The cam mechanism 150 is provided between the main clutch 130 and the pilot clutch 144 and transmits torque based on the phase difference between the rotation of the outer case 110 and the rotation of the inner shaft 120 transmitted through the pilot clutch 144 in the axial direction. The main clutch 130 is pressed by converting into a pressing force. The cam mechanism 150 includes a support cam member 151, a moving cam member 152, a cam ball 153, a first elastic member 154, a second elastic member 155, and a disc spring deformation restricting member 156.

  The support cam member 151 is formed in an annular shape having a male spline on the outer peripheral side. A support-side cam groove 151a is formed on the left end surface of the support cam member 151 in FIG. The support cam member 151 is provided with a gap with respect to the outer peripheral surface of the inner shaft 120, and is supported on the right end surface of the rear housing 112 in FIG. 2 via a thrust bearing 160. That is, the support cam member 151 is relatively rotatable with respect to the inner shaft 120 and the rear housing 112 and is provided so as to be restricted with respect to the axial direction. Further, the male spline of the support cam member 151 is fitted to the female spline of the inner pilot clutch plate 144a. Here, details of the support-side cam groove 151a of the support cam member 151 will be described later with reference to FIGS.

  The moving cam member 152 is formed of an iron-based material, and is formed in an annular shape having a female spline 152a on the inner peripheral side. The moving cam member 152 is disposed on the left side of the support cam member 151 in FIG. A moving cam groove 152b is formed on the right end surface of the moving cam member 152 in FIG. 2 so as to face the support cam groove 151a of the support cam member 151 in the axial direction. The female spline 152 a of the moving cam member 152 is fitted to the male spline 120 a of the inner shaft 120. Accordingly, the moving cam member 152 rotates together with the inner shaft 120. Further, the left end surface of the movable cam member 152 in FIG. 2 is in a state where it can abut on the inner main clutch plate 131 disposed at one end of the main clutch 130. When the moving cam member 152 moves to the left side of FIG. 2, it pushes against the inner main clutch plate 131 to the left side of FIG. 2. Here, details of the moving cam groove 152b of the moving cam member 152 will be described later with reference to FIGS. 3 to 5 together with the supporting cam groove 151a.

  The cam ball 153 has a spherical shape, and is interposed between the support-side cam groove 151a and the moving-side cam groove 152b facing the support-side cam groove 151a. That is, when a phase difference occurs between the support cam member 151 and the movable cam member 152 due to the action of the cam ball 153 and the respective cam grooves 151 a and 152 b, the movable cam member 152 moves in the axial direction with respect to the support cam member 151. Move in the direction of separation (left side in FIG. 2). The axial distance of the movable cam member 152 relative to the support cam member 151 increases as the phase difference between the support cam member 151 and the movable cam member 152 increases.

  The first elastic member 154 is interposed between the step end surface formed on the right side of the male spline 120a of the inner shaft 120 in FIG. 2 and the left end surface of the movable cam member 152 in FIG. The first elastic member 154 is a coil spring, and generates an axial force according to the axial length. That is, when the moving cam member 152 moves to the main clutch 130 side, the first elastic member 154 biases the moving cam member 152 in the axial direction opposite to the main clutch 130 side with respect to the inner shaft 120. To do.

  The second elastic member 155 is interposed between the end surface of the inner main clutch plate 131 at one end and the left end surface in FIG. 2 of the moving cam member 152 facing the second elastic member 155. The second elastic member 155 is a disc spring, and generates an axial force according to the axial length. In particular, the spring constant of the second elastic member 155 is set larger than the spring constant of the first elastic member 154. Furthermore, the axial length of the second elastic member 155 in the unloaded state is shorter than the axial length of the first elastic member 154 in the unloaded state. That is, after the moving cam member 152 moves to the main clutch 130 side and the first elastic member 154 generates a biasing force, the second elastic member 155 moves the moving cam member 152 to the main clutch 130 side with respect to the inner shaft 120. It is biased in the axial direction opposite to.

  The second elastic member 155 biases the radial position of the inner main clutch plate 131 where the restriction pin 133 is disposed. That is, when the second elastic member 155 presses the inner main clutch plate 131, the regulating pin 133 receives the urging force on the back surface thereof. Here, in the present embodiment, the second elastic member 155 is configured to urge the moving cam member 152 against the inner main clutch plate 131, but similarly to the first elastic member 154, Thus, the movable cam member 152 may be biased.

  The disc spring deformation restricting member 156 is formed in an annular shape, and is interposed between the main clutch 130 and the moving cam member 152 in the axial direction. That is, the disc spring deformation restricting member 156 is disposed on the radially outer side of the second elastic member 155. Accordingly, the disc spring deformation restricting member 156 restricts deformation of the second elastic member 155 so that the axial deformation amount is narrower than the axial width of the disc spring deformation restricting member 156. The disc spring deformation restricting member 156 is disposed at a radial position where the inner main clutch plate 131 and the outer main clutch plate 132 overlap. Accordingly, the disc spring deformation restricting member 156 transmits the pressing force applied to the main clutch 130 by the movable cam member 152.

(Composition of cam mechanism)
Next, a detailed configuration of the cam mechanism 150 will be described with reference to FIGS. First, the support side cam groove 151a will be described with reference to FIGS. As shown in FIGS. 3 and 5, the support-side cam groove 151 a is formed in the central portion of the circumferential direction, the central portion 151 a 1 having a deep depth from the end surface, and adjacent to both sides in the circumferential direction of the central portion 151 a 1. And an end portion 151a2 having a shallow depth.

  As shown in FIG. 5, the circumferential cut surface shape of the central portion 151 a 1 is formed such that the angle with respect to the axis orthogonal to the axis is the first angle φ1. The first angle φ1 is 45 °, for example. That is, when the cam ball 153 moves in the circumferential direction in the central portion 151a1, it moves in the direction of the first angle φ1. Further, the circumferential cut surface shape of the end portion 151a2 is formed so that the angle with respect to the axis perpendicular to the axis is the second angle φ2, as shown in FIG. The second angle φ2 is set to be smaller than the first angle φ1. The second angle φ2 is 5 °, for example. That is, when the cam ball 153 moves in the circumferential direction in the end portion 151a2, the cam ball 153 moves in the direction of the second angle φ2. And the boundary part of the center part 151a1 and the edge part 151a2 in the support side cam groove 151a is smoothly connected by the convex curved surface in order to make the cam ball 153 move easily.

  The moving cam groove 152b is shown in FIGS. The moving cam groove 152b is formed in the same shape as the support cam groove 151a. That is, the moving cam groove 152b includes a central portion 152b1 and an end portion 152b2. That is, the circumferential cut surface shape of the center portion 152b1 has an angle with respect to the axis orthogonal plane being the first angle φ1, and the circumferential cut surface shape of the end portion 152b2 has the angle with respect to the axis orthogonal plane being the second angle φ2.

  The first cam portions 151a1-152b1 are formed by the central portion 151a1 of the support-side cam groove 151a and the central portion 152b1 of the moving-side cam groove 152b. A second cam portion 151a2-152b2 is formed by the end portion 151a2 of the support side cam groove 151a and the end portion 152b2 of the moving side cam groove 152b.

(Operation of the moving cam member with respect to the support cam member)
Next, the operation of the moving cam member 152 relative to the support cam member 151 will be described with reference to FIGS. As shown in FIG. 5, when the phase difference of the movable cam member 152 with respect to the support cam member 151 is zero, the cam ball 153 is located at the deepest position of the first cam portions 151a1-152b1. At this time, the cam ball 153 is in contact with the center portion 151a1 of the support side cam groove 151a and the center portion 152b1 of the moving side cam groove 152b.

  When the phase difference of the movable cam member 152 is slightly generated with respect to the support cam member 151, as shown in FIG. 6, the cam ball 153 is separated from the second cam portion 151a2-152b2 in the first cam portion 151a1-152b1. Move to the boundary side. Then, the moving cam member 152 moves in the axial direction with respect to the support cam member 151. Further, when a phase difference of the moving cam member 152 occurs with respect to the support cam member 151, as shown in FIG. 7, the cam ball 153 is moved between the first cam portion 151a1-152b1 and the second cam portion 151a2-152b2. Move to the boundary. Then, the moving cam member 152 further moves in the axial direction with respect to the support cam member 151. Further, when a phase difference of the moving cam member 152 occurs with respect to the support cam member 151, the cam ball 153 moves in a direction away from the boundary in the second cam portions 151a2-152b2, as shown in FIG. Then, the moving cam member 152 further moves in the axial direction with respect to the support cam member 151.

(Operation of driving force transmission device)
Next, the operation of the driving force transmission device 100 having the above-described configuration will be described with reference to FIGS. A state where no current is supplied to the electromagnetic coil 142 of the electromagnetic clutch device 140 will be described as an initial state. In this case, since the pilot clutch 144 is not engaged, the outer case 110 and the support cam member 151 are in a relatively rotatable state.

  Further, since the moving cam member 152 is spline-fitted with the inner shaft 120, the moving cam member 152 rotates together with the inner shaft 120. As shown in FIG. 2, the moving cam member 152 is always urged to the right in FIG. 2 by the first elastic member 154. Further, since the rotation of the support cam member 151 is restricted only by the moving cam member 152 via the cam ball 153, the support cam member 151 rotates with the rotation of the moving cam member 152. Therefore, there is no phase difference between the support cam member 151 and the movable cam member 152. Then, the cam ball 153 is positioned at the deepest position of the first cam portions 151a1-152b1, as shown in FIG. Therefore, the movable cam member 152 is located at the position closest to the support cam member 151 side, that is, the position farthest from the main clutch 130. Therefore, the engagement of the main clutch 130 is reliably released. Therefore, drag torque can be reduced.

  At this time, the moving cam member 152 is located on the right side of FIG. Further, since the distance between the one end of the inner main clutch plate 131 and the moving cam member 152 is the longest, the second elastic member 155 does not generate an urging force.

  Subsequently, a current is supplied to the electromagnetic coil 142 of the electromagnetic clutch device 140 when the outer case 110 and the inner shaft 120 have a rotational difference. As a result, a loop-shaped magnetic circuit that circulates through the yoke 141, the rear housing 112, and the armature 143 with the electromagnetic coil 142 as a base point is formed.

  By forming the magnetic circuit, the armature 143 is drawn toward the yoke 141 side, that is, toward the right side in FIGS. As a result, the armature 143 presses the pilot clutch 144, and the inner pilot clutch plate 144a and the outer pilot clutch plate 144b are frictionally engaged. Then, the rotational torque of the outer case 110 is transmitted to the support cam member 151 via the pilot clutch 144, and the support cam member 151 rotates.

  Then, a rotation difference is generated between the support cam member 151 and the movable cam member 152. The movable cam member 152 moves in the axial direction with respect to the support cam member 151 by the action of the cam ball 153 and the cam grooves 151a and 152b. This operation is as described with reference to FIGS.

  When the movable cam member 152 moves to the left side of FIGS. 2 and 9, the first elastic member 154 and the second elastic member 155 are contracted and deformed. Then, the movable cam member 152 presses the main clutch 130 via the disc spring deformation restricting member 156. Then, the inner main clutch plate 131 and the outer main clutch plate 132 are frictionally engaged. As a result, the torque of the outer case 110 is transmitted to the inner shaft 120 via the main clutch 130.

  Here, as shown in FIG. 9, in a state where the moving cam member 152 presses the main clutch 130, the second elastic member 155 presses the inner main clutch plate 131 and the back side thereof is supported by the restriction pin 133. Yes. Therefore, even if the inner main clutch plate 131 is urged by the second elastic member 155, the inner main clutch plate 131 is not deformed.

  Further, as shown in FIG. 9, in the state where the disc spring deformation restricting member 156 presses the main clutch 130, the axial length of the second elastic member 155 that is a disc spring is sufficiently secured. Therefore, it is possible to prevent the second elastic member 155 that is a disc spring from being deformed and reversed.

(Operation of the first and second cam parts and the first and second elastic members)
In the driving force transmission device 100 described above, when the moving cam member 152 moves in the axial direction with respect to the support cam member 151, the first cam portion 151a1-152b1, the second cam portion 151a2-152b2, the first elastic member 154, and The operation of the second elastic member 155 will be described with reference to FIGS. In each figure, the horizontal axis is the phase difference θ between the support cam member 151 and the movable cam member 152. The phase difference θ0 is in a state where the phase difference is zero as shown in FIG. The phase difference θ1 is the state shown in FIG. 6 and is the time when the second elastic member 155 starts to generate the urging force. The phase difference θ2 is the state shown in FIG. 7, and the cam ball 153 is located at the boundary between the first cam portion 151a1-152b1 and the second cam portion 151a2-152b2. This phase difference θ2 corresponds to a predetermined position of the first cam portion in the present invention. The phase difference θ3 is a state where the cam ball 153 is positioned at the second cam portion 151a2-152b2, as shown in FIG. Moreover, in FIGS. 11-13, the case where the 2nd elastic member 155 is not provided is shown with a dashed-dotted line as a comparative example.

  The axial displacement amount X of the movable cam member 152 with respect to the phase difference θ is as shown in FIG. The axial displacement amount of the moving cam member 152 in the case of the phase difference θ0 is X0. The cam ball 153 moves on the first cam portions 151a1-152b1 between the phase differences θ0 to θ2. Therefore, during this time, the displacement amount is in accordance with the first angle φ1 of the first cam portions 151a1-152b1. The axial displacement amount of the movable cam member 152 at the phase difference θ2 is X2.

  Then, the cam ball 153 moves on the second cam portions 151a2-152b2 between the phase difference θ2 and θ3. Therefore, during this time, the amount of displacement is in accordance with the second angle φ2 of the second cam portion 151a2-152b2. The axial displacement amount of the moving cam member 152 at the phase difference θ3 is X3. Here, as shown in FIG. 5, the second angle φ2 is smaller than the first angle φ1. Therefore, the amount of change in the axial displacement amount X of the movable cam member 152 with respect to the phase difference θ is greater between θ0 and θ2 than between θ2 and θ3.

  The urging forces of the first and second elastic members 154 and 155 with respect to the phase difference θ are as shown by the solid line in FIG. As shown by the solid line in FIG. 11, the urging force of only the first elastic member 154 is generated at the phase difference θ0. The urging force at this time is Fa0. In the phase difference θ0 to θ1, only the first elastic member 154 generates a biasing force, and the second elastic member 155 does not generate a biasing force. Therefore, during this period, a force corresponding to the amount of axial contraction of the first elastic member 154 is obtained. The amount of axial contraction of the first elastic member 154 corresponds to the amount of axial displacement of the movable cam member 152. The biasing force at the phase difference θ1 is Fa1.

  In addition to the first elastic member 154, the second elastic member 155 generates a biasing force between the phase differences θ1 to θ2. Accordingly, during this time, the force is in accordance with the axial contraction amount of the first elastic member 154 and the second elastic member 155. That is, the amount of change in the urging force between the phase differences θ1 to θ2 is larger than the amount of change in the urging force between the phase differences θ0 to θ1 due to the influence of the second elastic member 155. The biasing force at the phase difference θ2 is Fa2.

  Similarly to the phase difference θ1 to θ2, the second elastic member 155 generates an urging force between the phase differences θ2 and θ3 in addition to the first elastic member 154. Accordingly, the force corresponding to the axial contraction amount of the first elastic member 154 and the second elastic member 155 is also applied during this time. Here, between the phase differences θ2 to θ3, as shown in FIG. 10, the change in the axial displacement amount of the movable cam member 152 with respect to the phase difference θ is smaller than that between the phase differences θ1 to θ2. Therefore, the change in the urging force between the phase differences θ2 to θ3 is smaller than the change in the urging force between the phase differences θ1 to θ2. Here, the urging force at the phase difference θ3 is Fa3.

  Here, the urging force by only the first elastic member 154 in the comparative example will be described. Since only the first elastic member 154 is present as shown by the one-dot chain line in FIG. 11, the phase difference θ0 to θ2 changes linearly, and the phase difference θ2 to θ3 changes linearly with different slopes. To do. That is, the urging force between the phase differences θ1 to θ3 in which the urging force of the second elastic member 155 is generated is different from that of the present embodiment.

  Next, the axial force Fb of the moving cam member 152 with respect to the phase difference θ is as shown by the solid line in FIG. Here, the moving cam member 152 moves toward the main clutch 130 against the urging force of the first and second elastic members 154 and 155. That is, the axial force is obtained by subtracting the biasing force of the first and second elastic members 154 and 155 from the force of the moving cam member 152 moving in the axial direction by the action of the cam ball 153 and the cam grooves 151a and 152b. It becomes power.

  As indicated by the solid line in FIG. 12, the axial force at the phase difference θ0 is Fb0. The axial force between the phase differences θ0 to θ1 changes linearly. The axial force at the phase difference θ1 is Fb1. The axial force between the phase differences θ1 to θ2 changes in a straight line having a gentler inclination than the inclination of the axial force between θ0 and θ1. The axial force at the phase difference θ2 is Fb2. The axial force between the phase differences θ2 to θ3 changes in a straight line having a steep slope compared to the slope of the axial force between θ1 and θ2. That is, since the cam ball 153 moves along the second angle φ2 of the second cam portion 151a2-152b2 between the phase differences θ2 to θ3, a large axial force by the moving cam member 152, that is, the main clutch by the moving cam member 152 is obtained. A large pressing force with respect to 130 can be obtained. The axial force at the phase difference θ3 is Fb3.

  Here, the axial force of the movable cam member 152 in the comparative example will be described. Since only the first elastic member 154 is present as shown by a one-dot chain line in FIG. 12, the phase difference θ0 to θ2 changes linearly, and the phase difference θ2 to θ3 changes linearly with different slopes. To do. That is, the urging force between the phase differences θ1 to θ3 in which the urging force of the second elastic member 155 is generated is different from that of the present embodiment.

  This embodiment shown by the solid line in FIG. 12 is compared with the comparative example shown by the one-dot chain line. Looking at the amount of change in the axial force before and after the phase difference θ2 between the two, it can be seen that the present embodiment is smaller than the comparative example. That is, according to the present embodiment, when the cam ball 153 exceeds the boundary between the first cam portion 151a1-152b1 and the second cam portion 151a2-152b2, the change in the axial force of the movable cam member 152 can be suppressed. is made of. In particular, by applying a disc spring having a large spring constant as the second elastic member 155, a change in the axial force of the movable cam member 152 can be more reliably suppressed.

  Next, the transmission torque Tr of the main clutch 130 with respect to the phase difference θ is as shown by a solid line in FIG. Here, the main clutch 130 generates the transmission torque Tr after the second elastic member 155 generates an urging force. That is, the transmission torque Tr is a value corresponding to the axial force Fb of the movable cam member 152 after the second elastic member 155 starts to generate the urging force.

  As shown by the solid line in FIG. 13, the transmission torque between the phase differences θ0 to θ1 is Tr0 (= 0). The transmission torque Tr between the phase differences θ1 to θ2 changes linearly. The transmission torque at the phase difference θ2 is Tr2. The transmission torque Tr between the phase differences θ2 to θ3 changes in a straight line having a steep inclination compared to the inclination of the axial force between θ1 and θ2. The transmission torque at the phase difference θ3 is Tr3.

  Here, the transmission torque Tr in the comparative example will be described. Here, the time point at which the movable cam member 152 generates the pressing force to the main clutch 130 will be described as the phase difference θ1. As shown by the one-dot chain line in FIG. 13, the transmission torque Tr between the phase differences θ0 to θ1 is zero. The transmission torque Tr changes linearly between the phase differences θ1 to θ2, and changes linearly with a large slope between the phase differences θ2 to θ3.

  The present embodiment indicated by the solid line in FIG. 13 is compared with the comparative example indicated by the alternate long and short dash line. In the phase differences θ1 to θ2 and θ2 to θ3, the transmission torque Tr in the present embodiment is smaller than the transmission torque in the comparative example. This is because, in this embodiment, the urging force of the second elastic member 155 acts in a direction that weakens the pressing force of the movable cam member 152 against the main clutch 130.

  When the amount of change in the transmission torque Tr before and after the phase difference θ2 between them is seen, it can be seen that the present embodiment is smaller than the comparative example. That is, according to this embodiment, when the cam ball 153 exceeds the boundary between the first cam portion 151a1-152b1 and the second cam portion 151a2-152b2, the change in the transmission torque Tr can be suppressed. As a result, discomfort to the driver can be reduced.

100: Driving force transmission device 110: Outer case (outer rotating member) 120: Inner shaft (inner rotating member) 130: Main clutch 131: Inner main clutch plate 132: Outer main clutch plate 133: Restriction pin (Inner clutch restricting member), 140: electromagnetic clutch device, 142: electromagnetic coil, 143: armature, 144: pilot clutch, 150: cam mechanism, 151: support cam member, 151a: support side cam groove, 152: moving cam member 152b: Movement side cam groove, 151a1-152b1: First cam portion, 151a2-152b2: Second cam portion, 153: Cam ball, 154: First elastic member, 155: Second elastic member, 156: Disc spring deformation restriction Member, φ1: first angle, φ2: second angle

Claims (4)

A cylindrical outer rotating member;
A shaft-like inner rotating member disposed coaxially in the outer rotating member so as to be relatively rotatable;
A main clutch that transmits torque between the outer rotating member and the inner rotating member;
An electromagnetic clutch device comprising a pilot clutch capable of transmitting the torque of the outer rotating member by attracting the armature by a magnetic force;
A phase difference between the rotation of the outer rotating member and the rotation of the inner rotating member, which is provided between the main clutch and the pilot clutch and transmitted via the pilot clutch, is converted into an axial pressing force. A cam mechanism for pressing the main clutch by moving the moving cam member in the axial direction;
In the driving force transmission device comprising:
The cam mechanism is
A support cam member that is spline-fitted to the pilot clutch and includes a support-side cam groove;
The moving cam member that is spline fitted to the inner rotating member and includes a moving cam groove;
A cam ball interposed between the support side cam groove and the movement side cam groove to move the movement cam member relative to the support cam member;
A first elastic member and a second elastic member for urging the movable cam member in the axial direction opposite to the main clutch side with respect to the inner rotating member or the main clutch;
With
The supporting cam groove and the moving cam groove are
A first cam portion whose angle with respect to the axis perpendicular to the axis is a first angle;
A second cam portion formed shallower than the first cam portion and adjacent to the first cam portion in the circumferential direction, and an angle with respect to the axis perpendicular to the axis being a second angle smaller than the first angle;
Configure
When the cam ball is positioned deeper than a predetermined position of the first cam portion, the first elastic member generates a biasing force, and the second elastic member does not generate a biasing force,
When the cam ball is positioned on a shallower side than the predetermined position of the first cam portion, and when the cam ball is positioned on the second cam portion, the first elastic member and the second elastic member exert a biasing force. Generated driving force transmission device. In claim 1,
A driving force transmission device in which a spring constant of the second elastic member is set larger than a spring constant of the first elastic member. In claim 1 or 2,
The main clutch is
A plurality of outer clutch plates that are spline-fitted to the outer rotating member;
An inner clutch plate that is splined to the inner rotating member and sandwiched between each of the plurality of outer clutch plates;
The inner clutch plate is disposed radially inward from the inner circumferential surface of the outer clutch plate, is sandwiched between inner clutch plates at both ends of the plurality of inner clutch plates, and receives the urging force from the second elastic member, thereby causing inner ends at the both ends. An inner clutch restricting member for restricting the approach of the clutch plate;
A driving force transmission device comprising: In any one of Claims 1-3,
The second elastic member is interposed between the main clutch and the moving cam member in an axial direction, and biases the moving cam in the axial direction opposite to the main clutch with respect to the main clutch. Spring,
The driving force transmission device is interposed between the main clutch and the moving cam member in the axial direction, transmits a pressing force applied to the main clutch by the moving cam member, and regulates an axial deformation amount of the disc spring. A driving force transmission device including a disc spring deformation regulating member.

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