Electric friction engagement device and method for detecting the abnormality thereof

Abstract

The present invention addresses the problem of implementing a structure capable of detecting a piston touch point and a clutch touch point. To solve the problem, when an electric friction engagement device (7) is switched from a connection mode to a disconnection mode, a phase (θ) related to the direction of rotation of a drive cam (34) at the time when the output torque (T) or current value (A) of a shift motor (66) starts increasing at an increase rate that is at least a first threshold is detected as a piston touch point (θp), and a phase (θ) related to the direction of rotation of the drive cam (34) at the time when the increase rate becomes equal to or lower than a second threshold is detected as a clutch touch point (θf).

Description

[[Technical Field]]

[0001] The present invention relates to an electric friction engagement device that uses a shift motor as a drive source to switch between a connection mode in which torque is transmitted between a first member and a second member and a disconnection mode in which torque is not transmitted. [[Background Art]]

[0002] In rotary mechanical devices such as automobiles and machine tools, a transmission is provided between a power source and a driven object in order to efficiently use the output of a power source such as an engine or an electric motor. When a gear-type stepped transmission is used, a clutch device that switches between a connection mode in which the output torque of the power source can be transmitted to the transmission and a disconnection mode in which the output torque cannot be transmitted is incorporated between the power source and the transmission. As such clutch devices, friction clutches that transmit power by friction between mutually opposing friction surfaces, dog clutches that transmit power by mutually meshing pawls, and the like are used.

[0003] A friction clutch can switch between a connection mode in which torque is transmitted between a pair of coaxially arranged rotating members and a disconnection mode in which torque is not transmitted, regardless of the phase difference or rotational speed difference between the pair of rotating members.

[0004] WO 2008 / 096438 A1 describes a normally-open friction clutch that uses a motor as a drive source to switch between a disconnection mode and a connection mode.

[0005] To switch the friction clutch described in WO 2008 / 096438 A1 to the connection mode, a motor rotationally drives a first cam plate in one circumferential direction via a reduction gear and a transmission mechanism, and separates the first cam plate from a second cam plate, thereby pressing a moving member against the elastic force of a return spring. This causes the drive plate and the driven plate to press against each other.

[0006] In contrast, to switch the friction clutch to the disengagement mode, the motor rotates the first cam plate in the opposite circumferential direction via the reduction gear and transmission mechanism, bringing the first cam plate and the second cam plate closer together, thereby releasing the force pressing the drive plate and the driven plate against each other. As a result, the gap between the drive plate and the driven plate widens due to the action of the return spring. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] International Publication No. 2008 / 096438 Pamphlet [Overview of the project] [Problems that the invention aims to solve]

[0008] In the friction clutch described in International Publication No. 2008 / 096438, when the drive plate and driven plate wear down, the piston touch point, which is the phase relative to the rotation direction of the first cam plate when the clutch engagement force begins to decrease, and the clutch touch point, which is the phase relative to the rotation direction of the first cam plate when the engagement force becomes zero, change when the friction clutch is switched from the engagement mode to the disengagement mode. Therefore, from the standpoint of ensuring good controllability of the friction clutch, it is desirable to accurately detect the piston touch point and the clutch touch point.

[0009] Furthermore, if the drive plate and driven plate are used beyond their respective wear limits, it can lead to failures such as seizing. Therefore, accurately detecting the piston touch point and clutch touch point is desirable to ensure the reliability of the friction clutch.

[0010] In view of the circumstances described above, this disclosure aims to realize an electrically operated friction engagement device capable of detecting piston touch points and clutch touch points. [Means for solving the problem]

[0011] An electric friction engagement device according to one aspect of the present disclosure comprises a first member, a second member, a friction engagement portion, an elastic biasing member, a cam device, and an electric actuator.

[0012] The second member is supported coaxially with the first member and capable of relative rotation with respect to the first member.

[0013] The friction engagement portion has at least one first friction plate and at least one second friction plate, which are supported to allow relative axial displacement, and is provided between the first member and the second member. The friction engagement portion switches to a state in which torque is transmitted between the first member and the second member by pressing the first friction plate and the second friction plate against each other, and switches to a state in which torque is not transmitted between the first member and the second member by releasing the force pressing the first friction plate and the second friction plate against each other.

[0014] The elastic biasing member is provided between the first member and the friction engagement portion, and elastically biases the first friction plate and the second friction plate in a direction that causes them to press against each other.

[0015] The cam device includes a drive cam supported to allow rotation relative to the first member and the second member, but unable to move in the axial direction, and a driven cam supported to allow relative rotation and axial movement relative to the drive cam. Based on the fact that the driven cam moves in a direction that increases the axial distance between it and the drive cam as the drive cam rotates, the cam device presses the elastic biasing member in a direction that releases the force pressing the first friction plate and the second friction plate against each other.

[0016] The electric actuator comprises a shift motor and a reduction gear, and the shift motor rotates the drive cam via the reduction gear.

[0017] An electric friction engagement device according to one aspect of the present disclosure has a function to detect the phase (rotation angle from a reference position) of the rotation direction of the drive cam when the shift motor rotates the drive cam via the reduction gear in order to switch the friction engagement portion from a state in which torque is transmitted between the first member and the second member to a state in which torque is not transmitted between the first member and the second member, as a piston touch point in which the elastic biasing member begins to press in a direction that releases the force pressing the first friction plate and the second friction plate against each other, when the output torque or current value of the shift motor begins to increase at an increase rate of 1 or more than a first threshold.

[0018] Furthermore, the electric friction engagement device has a function to detect the phase of the rotation direction of the drive cam when the shift motor rotates the drive cam via the reduction gear in order to switch the friction engagement portion from a state in which torque is transmitted between the first member and the second member to a state in which torque is not transmitted between the first member and the second member, after passing the piston touch point and when the rate of increase becomes less than or equal to the second threshold, as the clutch touch point where the force pressing the first friction plate and the second friction plate against each other becomes zero.

[0019] An electric friction engagement device according to one aspect of the present disclosure may include a function for determining whether the piston touch point or the clutch touch point is within a predetermined angular range.

[0020] An electric friction engagement device according to one aspect of the present disclosure may include a function to determine whether the maximum output torque or current value of the shift motor is within a predetermined range when the shift motor rotates the drive cam via the reduction gear in order to switch the friction engagement portion from a state in which torque is transmitted between the first member and the second member to a state in which torque is not transmitted between the first member and the second member.

[0021] In an electric friction engagement device according to one aspect of the present disclosure, the elastic biasing member may include a piston supported to allow axial displacement relative to the first member, and an elastic member provided between the first member and the piston.

[0022] A touch point detection method for an electric friction engagement device according to one aspect of the present disclosure includes the step of detecting the phase with respect to the rotational direction of the drive cam when the shift motor rotates the drive cam via the reduction gear in order to switch the friction engagement portion from a state in which torque is transmitted between the first member and the second member to a state in which torque is not transmitted between the first member and the second member, as a piston touch point when the phase with respect to the rotational direction of the drive cam when the output torque or current value of the shift motor begins to increase at an increase rate of 1 or more than a first threshold, and the elastic biasing member begins to press in a direction that releases the force pressing the first friction plate and the second friction plate against each other.

[0023] Furthermore, the detection method includes the step of detecting the phase of the rotation direction of the drive cam when the shift motor rotates the drive cam via the reduction gear in order to switch the friction engagement portion from a state in which torque is transmitted between the first member and the second member to a state in which torque is not transmitted between the first member and the second member, after passing the piston touch point and when the rate of increase becomes less than or equal to the second threshold, as the clutch touch point where the force pressing the first friction plate and the second friction plate against each other becomes zero.

[0024] An abnormality detection method for an electric friction engagement device according to one aspect of this disclosure is: The process involves performing the touch point detection method for the electric friction engagement device, and A step of determining whether the piston touch point or the clutch touch point is at or above a predetermined angle, It is equipped with.

[0025] An abnormality detection method for an electric friction engagement device according to one aspect of this disclosure is: The system may include a step of determining whether the maximum output torque or current value of the shift motor is within a predetermined range when the shift motor rotates the drive cam via the reduction gear in order to switch the friction engagement portion from a state in which torque is transmitted between the first member and the second member to a state in which torque is not transmitted between the first member and the second member. [Effects of the Invention]

[0026] According to one aspect of this disclosure, an electric friction engagement device and its abnormality detection method can accurately detect piston touch points and clutch touch points. [Brief explanation of the drawing]

[0027] [Figure 1] Figure 1 is a schematic cross-sectional view showing a drive system incorporating a two-speed transmission equipped with an electric friction engagement device, which is an example of an embodiment of the present disclosure. [Figure 2] Figure 2(a) shows the torque transmission path in the reduced gear ratio mode of the two-speed transmission in this example, and Figure 2(b) shows the torque transmission path in the high reduction ratio mode of the two-speed transmission in this example. [Figure 3] Figure 3 is a perspective view of the two-speed transmission in this example. [Figure 4] Figure 4 is a cross-sectional view of the two-speed transmission in this example. [Figure 5] Figure 5 is a perspective view showing the planetary gear mechanism removed from the two-speed transmission in this example. [Figure 6] Figure 6 is a cross-sectional view showing the planetary gear mechanism removed from the two-speed transmission in this example. [Figure 7] Figure 7 is an exploded perspective view of the two-speed transmission in this example. [Figure 8] Figure 8 is an exploded perspective view showing the worm and two support bearings removed from the electric friction engagement device in this example. [Figure 9] Figure 9 is an exploded perspective view showing the first and second friction plates removed from the electric friction engagement device in this example. [Figure 10] Figure 10 is an enlarged view of section X in Figure 4. [Figure 11] Figure 11 is a perspective view showing the drive cam removed from the electric friction engagement device in this example. [Figure 12] Figure 12 is an exploded perspective view showing the driven cam and rolling elements removed from the electric friction engagement device in this example. [Figure 13] Figure 13(a) is a perspective view showing the flange portion and pressing member of the rotating member removed from the two-speed transmission of this example, and Figure 13(b) is an exploded perspective view showing the flange portion and pressing member of the rotating member removed. [Figure 14] Figures 14(a) and 14(b) are diagrams showing the relationship between the rotation angle of the drive cam and the output torque and current value of the shift motor when switching the electric friction engagement device of this example from connection mode to disconnection mode. Figure 14(a) shows the case when the first and second friction plates are new and not worn, while Figure 14(b) shows the case when the first and second friction plates have worn significantly. [Figure 15] Figure 15 is a cross-sectional view showing the electric friction engagement device in this example switched to connection mode. [Figure 16] Figure 16 is a cross-sectional view showing the state in which the pressing member and the piston are in contact during the switching from the connection mode to the disconnection mode of the electric friction engagement device in this example. [Figure 17] Figure 17 is a cross-sectional view showing the electric friction engagement device in this example switched to the cutting mode. [Figure 18] Figure 18 is a flowchart illustrating the characteristic operation of the electric friction engagement device in this example. [Modes for carrying out the invention]

[0028] An example of an electric friction engagement device 7 according to one embodiment of the present disclosure will be described with reference to Figures 1 to 18, based on an example in which the electric friction engagement device 7 is incorporated into a two-speed transmission 1 for an automobile. The two-speed transmission 1 is positioned between a drive source 2, such as an electric motor or an engine, and a differential 3, and increases the output torque of the drive source 2, that is, reduces its rotation, or transmits it to the differential 3 without increasing it.

[0029] Figures 1 to 2(b) schematically represent the elements constituting the drive source 2, the differential 3, and the two-speed transmission 1 in order to facilitate understanding of this disclosure.

[0030] The two-speed transmission 1 in this example includes an input member 4 that can be rotationally driven by a drive source 2, an output member 5 that is connected to a differential 3 to enable torque transmission, and an electric friction engagement device 7.

[0031] The electric friction engagement device 7 comprises a first member, a second member which is composed of an input member 4 or is connected to enable the transmission of torque from the input member 4, a friction engagement portion 26, an elastic biasing member 27, a cam device 28, and an electric actuator 29. In this example, the first member is composed of a rotating member 6. The second member is composed of an input member 4.

[0032] The input member 4, which corresponds to the second member, is coaxial with the rotating member 6, which is the first member, and is capable of relative rotation with respect to the rotating member 6.

[0033] More specifically, the input member 4 is composed of a housing that accommodates the two-speed transmission 1, and is rotatably supported by a rolling bearing (not shown) or the like, with respect to a fixed part 10 that does not rotate even during use. In this example, the input member 4 is cylindrical (hollow). The input member 4 also has an input gear 13 at one end on the axial side (right side in Figure 1) that meshes with a drive gear 12 provided on the output shaft 11 of the drive source 2. In other words, the input member 4 is rotationally driven by the drive source 2.

[0034] In this example, the output member 5 is supported radially inward of the input member 4, allowing for relative rotation with respect to the input member 4. The output member 5 also has an output gear 14 at one end on its axial side. The output gear 14 meshes with a gear provided at the input of the differential 3. In other words, the output member 5 is connected to the input of the differential 3, enabling the transmission of torque.

[0035] In this example, the rotating member 6, which corresponds to the first member, is supported coaxially with the input member 4 and the output member 5, and is capable of relative rotation with respect to the input member 4 and the output member 5. More specifically, the rotating member 6 is rotatably supported with respect to the fixed portion 10 via a braking device 8, a cam device 28, and a radial bearing 38 for rotatably supporting the drive cam 34 constituting the cam device 28 with respect to the rotating member 6.

[0036] In this example, the rotating member 6 has a small-diameter flange portion 15 projecting radially outward in the axial middle portion, and a flange portion 16 projecting radially outward in the portion located on the other axial side (left side in Figure 1) from the small-diameter flange portion 15.

[0037] The flange portion 16 has a hollow circular plate-shaped first ring portion 18, a first cylindrical portion 19 bent axially from the radially outer end of the first ring portion 18, a hollow circular plate-shaped second ring portion 20 bent radially from the axially outer end of the first cylindrical portion 19, and a second cylindrical portion 21 bent axially from the radially outer end of the second ring portion 20. The first ring portion 18 has partially arc-shaped through holes 17 at multiple locations in the radially intermediate portion for inserting the partially cylindrical portion 63 of the pressing member 58 that constitutes the electric friction engagement device 7.

[0038] In this example, the rotating member 6 is constructed by externally fitting and fixing a stepped cylindrical member 23, as shown on the left side of Figure 13(b), onto a shaft member 22 having a small-diameter flange portion 15. Specifically, the stepped cylindrical member 23 has a first ring portion 18, a first cylindrical portion 19, a second ring portion 20, a second cylindrical portion 21, and a small-diameter cylindrical portion 24 that is bent axially from the radially inward end of the first ring portion 18 toward the other side. The stepped cylindrical member 23 of the rotating member 6 is supported and fixed by spline engagement of a female spline portion 25 provided on the inner circumferential surface of the small-diameter cylindrical portion 24 with a male spline portion provided on the outer circumferential surface of the shaft member 22. However, the rotating member can also be constructed by joining and fixing the stepped cylindrical member and the shaft member by press-fitting, welding, or other means.

[0039] In this example, the electric friction engagement device 7 is provided between the input member 4 and the rotating member 6, and switches between a connection mode in which torque is transmitted between the input member 4 and the rotating member 6, and a disconnection mode in which torque is not transmitted.

[0040] The friction engagement portion 26 constituting the electric friction engagement device 7 has at least one first friction plate 30 and at least one second friction plate 31, which are supported to allow relative displacement in the axial direction, and is provided between the first member (rotating member 6) and the second member (input member 4).

[0041] The friction engagement portion 26 switches to a state in which torque is transmitted between the first member (rotating member 6) and the second member (input member 4) by pressing the first friction plate 30 and the second friction plate 31 against each other, that is, a state in which the first member (rotating member 6) and the second member (input member 4) rotate as a single unit. Conversely, the friction engagement portion 26 switches to a state in which torque is not transmitted between the first member (rotating member 6) and the second member (input member 4) by releasing the force that presses the first friction plate 30 and the second friction plate 31 against each other, that is, a state in which the first member (rotating member 6) and the second member (input member 4) rotate relative to each other.

[0042] In this example, the friction engagement portion 26 is composed of a multi-plate clutch formed by alternately stacking a plurality of first friction plates 30 supported by a rotating member 6 and a plurality of second friction plates 31 supported by an input member 4.

[0043] Multiple first friction plates 30 are supported on the outer circumferential surface of the first cylindrical portion 19, allowing for axial displacement.

[0044] Multiple second friction plates 31 are supported on the inner circumferential surface of the axial end of the input member 4, allowing for axial displacement.

[0045] The elastic biasing member 27 is provided between the first member (rotating member 6) and the friction engagement portion 26, and elastically biases the first friction plate 30 and the second friction plate 31 in a direction that causes them to press against each other. In this example, the elastic biasing member 27 has a piston 32 and an elastic member 33.

[0046] The piston 32 is supported so as to be able to move axially relative to the rotating member 6. In this example, the piston 32 is configured in the shape of a hollow circular plate and is supported so as to be able to move axially relative to the rotating member 6 around the portion of the rotating member 6 between the small diameter flange portion 15 and the flange portion 16 in the axial direction. The piston 32 has its axial end face on the other side of the radially outer portion facing the axial side of the first friction plate 30 that is located furthest to the axial side of the first friction plate 30.

[0047] The elastic member 33 is provided between the rotating member 6 and the piston 32. In this example, the elastic member 33 is elastically compressed and sandwiched between the other axial side of the small-diameter flange portion 15 of the rotating member 6 and one axial side of the piston 32. That is, the elastic biasing member 27, by the force with which the elastic member 33 tries to return to its original shape, presses the first friction plate 30 on the axial side toward the other axial side via the piston 32, thereby elastically biasing the first friction plate 30 and the second friction plate 31 in a direction that causes them to press against each other.

[0048] In this example, the elastic member 33 is composed of at least one (two in this example) disc springs. However, the specific configuration of the elastic member is not particularly limited when implementing this disclosure. For example, the elastic member may be composed of at least one coil spring.

[0049] The cam device 28 includes a drive cam 34, a driven cam 35, and a plurality of rolling elements 36. As the drive cam 34 rotates, the cam device 28 moves the driven cam 35 in a direction that increases the axial distance between it and the drive cam 34, and based on this, presses the elastic biasing member 27 in a direction that releases the force pressing the first friction plate 30 and the second friction plate 31 against each other.

[0050] The drive cam 34 is supported relative to the rotating member 6 in such a way that it can rotate relative to both the rotating member 6 and the input member 4, but cannot be displaced axially relative to the rotating member 6. In this example, as shown in Figure 4 and other figures, the drive cam 34 is supported relative to the rotating member 6 by a cylindrical member 37, a radial bearing 38, and an angular contact ball bearing 39, allowing for relative rotation with respect to the rotating member 6.

[0051] The cylindrical member 37 has a cylindrical portion 40 and an outward-facing flange portion 41 that is bent radially outward from the other axial end of the cylindrical portion 40. The outward-facing flange portion 41 of the cylindrical member 37 is supported and fixed to the fixing portion 10 by screws or the like.

[0052] The radial bearing 38 has an inner ring 42 fitted and fixed to the axial end of the rotating member 6, an outer ring 43 fitted and fixed to the cylindrical portion 40 of the cylindrical member 37, and a plurality of rolling elements 44 arranged to roll freely between the inner ring 42 and the outer ring 43. In the illustrated example, the radial bearing 38 is made of a double-row deep groove ball bearing using balls as the rolling elements 44. However, the radial bearing is not particularly limited as long as it enables relative rotation between the first member and the cam device and can support the axial biasing force by the elastic biasing member, and can be made of, for example, a deep groove ball bearing, a radial angular contact ball bearing, or a radial tapered roller bearing.

[0053] The angular contact ball bearing 39 has an inner ring 45 fitted and fixed to the cylindrical portion 40 of a cylindrical member 37, an outer ring 46 fitted and fixed to the drive cam 34, and a plurality of balls 47 that are rotatably arranged between the inner ring 45 and the outer ring 46.

[0054] The driven cam 35 is supported so as to be able to rotate relative to the drive cam 34 and to be able to be moved in the axial direction. More specifically, the driven cam 35 is positioned around the rotating member 6 so as to be able to be moved only in the axial direction. In this example, the driven cam 35 has a hollow circular plate shape and is supported so as to be able to be moved in the axial direction relative to the fixed portion 10. In this example, the driven cam 35 is supported so as to be able to be moved in the axial direction relative to the fixed portion 10 by spline-engaging a female spline portion 51 provided on the inner circumferential surface of the driven cam 35 with a male spline portion 52 provided on the outer circumferential surface of one axial side portion of the cylindrical portion 40 of the cylindrical member 37.

[0055] However, the method of supporting the driven cam relative to the fixed part is not particularly limited, as long as the driven cam can be supported so that it can only be displaced axially relative to the fixed part. For example, the driven cam can be supported so that it can be displaced axially relative to the fixed part by key-engaging a protrusion on one of the driven cam and the fixed part with a recess on the other.

[0056] In this example, as shown in Figure 12, the driven cam 35 has rectangular holes 53 that penetrate axially at multiple locations (three locations in the illustrated example) in the circumferential direction in the radially intermediate part, and substantially semicircular plate-shaped support plate portions 54a and 54b that protrude from both radial sides of each rectangular hole 53 toward one axial side. Of the support plate portions 54a and 54b, the radially outer support plate portion 54a has a support hole 55 which is a circular hole that penetrates radially, and the radially inner support plate portion 54b has a support recess 56 with a circular opening on its radially outer surface.

[0057] The driven cam 35 faces the piston 32 of the elastic biasing member 27 via a thrust bearing 57 and a pressing member 58.

[0058] The thrust bearing 57 is provided between the pressing member 58 and the driven cam 35. The thrust bearing 57 has a pair of raceway rings 59a and 59b and a plurality of rolling elements 60 that are rotatably arranged between the pair of raceway rings 59a and 59b. Of the pair of raceway rings 59a and 59b, the raceway ring 59b on the axial side is supported and fixed to the driven cam 35.

[0059] The pressing member 58 has a cylindrical base 62 and a partial cylindrical portion 63 that protrudes axially from multiple locations (three locations in the illustrated example) in the circumferential direction of one axial end of the base 62. The other axial end of the base 62 supports and fixes the axial raceway 59a of a pair of raceway rings 59a, 59b of the thrust bearing 57. The partial cylindrical portion 63 is inserted through the through hole 17 of the rotating member 6, and the tip of the partial cylindrical portion 63 (the axial end) faces the radial middle portion of the other axial side of the piston 32.

[0060] In this example, a preloading means 61 for applying preload to the thrust bearing 57 is provided between the pressing member 58 and the rotating member 6. The preloading means 61 is elastically compressed and sandwiched between the pressing member 58 and the other axial side of the first ring portion 18 of the flange portion 16 constituting the rotating member 6. As a result, as shown in Figure 2(b), even when the piston 32 is pressed toward one axial side against the elastic restoring force of the elastic member 33, preload is applied to the thrust bearing 57, and the thrust bearing 57 is prevented from falling out from between the elastic biasing member 27 and the cam device 28.

[0061] Furthermore, the elasticity of the preload-applying means 61 is less than the elastic restoring force of the elastic member 33. The preload-applying means 61 can be composed of, for example, at least one disc spring or at least one coil spring. In this example, the preload-applying means 61 is composed of one coil spring.

[0062] In this example, the cam device 28 includes a plurality of rolling elements 36 (three in this example) and a drive cam surface 48 provided on the drive cam 34, as means for displacing the drive cam 34 and the driven cam 35 relative to each other.

[0063] As shown in Figure 11, the drive cam surface 48 is constructed by arranging an equal number of recesses and protrusions alternately in the circumferential direction on the radially inner portion of one axial side of the drive cam 34. The drive cam 34 has wheel teeth 49, which are helical gears, on its outer circumferential surface. Furthermore, the drive cam 34 has pin portions 50 that protrude toward one axial side at multiple locations (three locations in the illustrated example) in the circumferential direction in the radially intermediate portion of one axial side.

[0064] Each of the rolling elements 36 is composed of a cylindrical roller and is supported to rotate freely relative to the support plate portions 54a and 54b via a cylindrical support shaft 64 and a plurality of rollers 65. Specifically, the outer end of the support shaft 64 in the radial direction with respect to the central axis of the driven cam 35 is fitted and fixed into the support hole 55 of the radially outer support plate portion 54a, and the inner end of the support shaft 64 in the radial direction with respect to the central axis of the driven cam 35 is fitted and fixed into the support recess 56 of the radially inner support plate portion 54b.

[0065] Multiple rollers 65 are held between the inner circumferential surface of the rolling element 36 and the outer circumferential surface of the axial intermediate portion of the support shaft 64 so as to be able to roll freely. As a result, the rolling element 36 is supported by the driven cam 35 so as to be able to rotate (rotate) freely around its rotation axis C, which is oriented radially from the central axis of the driven cam 35.

[0066] With the rolling elements 36 supported by the driven cam 35, the axially opposite portion of the rolling elements 36 is positioned inside the rectangular hole 53. Each of the rolling elements 36 has its outer circumferential surface in rolling contact with the drive cam surface 48 provided on the axially opposite side of the drive cam 34.

[0067] In the cam device 28, as the drive cam 34 rotates, the amount by which the rolling elements 36 ride up from the bottom of the recess that constitutes the drive cam surface 48 increases or decreases, causing the driven cam 35 to move in the axial direction.

[0068] In other words, when the drive cam 34 is rotated in a predetermined direction, the amount by which the rolling elements 36 ride up from the bottom of the recess constituting the drive cam surface 48 increases, causing the driven cam 35 to move to one side in the axial direction. When the driven cam 35 moves to one side in the axial direction, the piston 32 of the elastic biasing member 27 is pressed toward one side in the axial direction via the thrust bearing 57 and the pressing member 58, and the elastic member 33 is elastically compressed.

[0069] This reduces, and eventually eliminates, the force pressing the first friction plate 30 and the second friction plate 31 against each other. Then, due to the action of the return spring 78, the gap between the first friction plate 30 and the second friction plate 31 widens, causing the friction engagement portion 26 to switch to a state where it does not transmit torque between the rotating member 6 and the input member 4.

[0070] In contrast, when the drive cam 34 is rotated in the opposite direction to the predetermined direction, the amount by which the rolling elements 36 ride up from the bottom of the recess constituting the drive cam surface 48 decreases, causing the driven cam 35 to move to the other axial side. When the driven cam 35 moves to the other axial side, the force pressing the piston 32 of the elastic biasing member 27 toward one axial side via the thrust bearing 57 and the pressing member 58 decreases.

[0071] When the force pressing the piston 32 in one axial direction decreases, the piston 32, thrust bearing 57, and pressing member 58 are pressed in the other axial direction mainly by the elastic restoring force of the first friction plate 30 and elastic member 33, and the piston 32 presses the second friction plate 31, which is closest to the axial direction, in the other axial direction. As a result, the first friction plate 30 and the second friction plate 31 press against each other, and the friction engagement portion 26 switches to a state in which torque is transmitted between the rotating member 6 and the input member 4.

[0072] In this example, rollers are used as rolling elements 36, and the rolling elements 36 are freely supported to rotate (rotate) around a rotation axis C that is oriented radially from the central axis of the driven cam 35. Therefore, the driven cam 35 can be reliably displaced in the axial direction based on the rotation of the drive cam 34.

[0073] When balls are used as rolling elements in a cam mechanism, slippage may occur at the rolling contact points between the surface of the rolling element and the surface of the driving cam and / or the driven cam when the driving cam is rotated. If slippage occurs at the rolling contact points between the surface of the rolling element and the surface of the driving cam and / or the driven cam, the driven cam may not be able to be displaced axially, or the amount of axial displacement of the driven cam may not be sufficient in relation to the amount of rotation of the driving cam.

[0074] In this example, since rollers are used as rolling elements 36, when the drive cam 34 is rotated, slippage can be prevented at the rolling contact point between the outer surface of the rolling elements 36 and the drive cam surface 48, and the driven cam 35 can be reliably displaced in the axial direction based on the rotation of the drive cam 34. However, when implementing this disclosure, balls can also be used as rolling elements constituting the cam device.

[0075] Furthermore, when implementing this disclosure, the cam device may also be a cam device in which a drive cam surface provided on a drive cam and a driven cam surface provided on a driven cam are directly engaged (slid), or a cam device having a driven cam having a guide groove that extends circumferentially on its outer peripheral surface and changes in the axial direction, and a drive cam having an engaging projection that engages to enable displacement along the guide groove.

[0076] The electric actuator 29 has a shift motor 66 and a reduction gear 67, and the shift motor 66 rotates the drive cam 34 of the cam device 28 via the reduction gear 67.

[0077] In this example, the reduction gear 67 is composed of a worm gear reduction gear. Specifically, the reduction gear 67 is formed by meshing the worm teeth, which are provided on the outer circumferential surface of a worm 68 connected to the output shaft of the shift motor 66, with the wheel teeth 49 provided on the outer circumferential surface of the drive cam 34. The worm 68 is rotatably supported relative to the fixed portion 10 by a pair of support bearings 69a and 69b.

[0078] However, the reduction gear 67 can also be configured by meshing a spur gear or bevel gear provided on the output shaft of the electric motor with a spur gear or bevel gear provided on the drive cam, or by stretching a belt or chain between the output shaft of the electric motor and the drive cam.

[0079] In this example, a return spring 78 (shown only in Figure 1) is further provided between the first friction plate 30 and the second friction plate 31, which elastically biases them in a direction that widens the gap between the first friction plate 30 and the second friction plate 31. The elasticity of the return spring 78 is less than the elastic restoring force of the elastic member 33 of the elastic biasing member 27.

[0080] In particular, in this example, when the electric friction engagement device 7 switches from a state in which torque is transmitted between the first member, the rotating member 6, and the second member, the input member 4 (connection mode), to a state in which torque is not transmitted between the rotating member 6 and the input member 4 (disconnection mode), the piston touch point θ at which the fastening force of the friction engagement portion 26 begins to decrease p A function to detect the clutch touch point θ where the fastening force becomes 0. f It is equipped with a function to detect such abnormalities. Furthermore, the electric friction engagement device 7 in this example is equipped with a function to detect abnormalities that may lead to failure.

[0081] After describing the additional components of the electric friction engagement device 7 in this example, the function will be further explained.

[0082] The braking device 8 is provided between the fixed portion 10 and the rotating member 6, and switches between a state in which the rotating member 6 can rotate relative to the fixed portion 10 and a state in which it cannot rotate. In this example, the braking device 8 is provided between the inner circumferential surface of the fixed portion 10 and the second cylindrical portion 21 of the rotating member 6.

[0083] The braking device 8 can be configured as a meshing or friction type braking device whose connected / disconnected state can be switched by an actuator. The actuator for switching the connected / disconnected state of the braking device is not particularly limited, and hydraulic actuators, electromagnetic actuators, etc., can be used.

[0084] In this example, the braking device 8 comprises an outer diameter cylindrical member 70, an inner diameter cylindrical member 71, at least one engagement pin (not shown), and a select plate 72.

[0085] The outer diameter cylindrical member 70 has an outer circumferential uneven surface 73 on its outer circumferential surface, which is formed by alternating recesses and protrusions in the circumferential direction. The outer diameter cylindrical member 70 is supported by the fixing portion 10 in a manner that prevents relative rotation by engaging the outer circumferential uneven surface 73 with the inner circumferential uneven surface provided on the inner circumferential surface of the fixing portion 10.

[0086] The inner diameter cylindrical member 71 is externally fitted and fixed to the second cylindrical portion 21 of the rotating member 6 so as not to rotate relative to it.

[0087] The engagement pin is detachably spanned between the outer diameter cylindrical member 70 and the inner diameter cylindrical member 71. In this example, the engagement pin is supported on the outer diameter cylindrical member 70 so as to protrude radially inward from the inner circumferential surface of the outer diameter cylindrical member 70 and is given elasticity directed radially inward. The inner diameter cylindrical member 71 has an engagement recess on its outer circumferential surface into which the tip of the engagement pin can be engaged.

[0088] The select plate 72 has a mode select portion which is a circumferentially oriented surface, and also has engagement holes (not shown) at multiple locations (three in this example) in the circumferential direction on the other axial side. A pin portion 50 provided on the drive cam 34 is fitted into each engagement hole without any rattle. As a result, the drive cam 34 and the select plate 72 rotate as a single unit (in the same direction and at the same speed).

[0089] The braking device 8 switches between a state in which the outer diameter cylindrical member 70 and the inner diameter cylindrical member 71 can rotate relative to each other and a state in which they cannot rotate relative to each other, based on the rotation of the select plate 72. That is, based on the rotation of the select plate 72, the convex portion constituting the mode select section pushes the engagement pin radially outward, thereby disengaging the engagement between the engagement pin and the engagement recess. This allows the inner diameter cylindrical member 71 to rotate relative to the outer diameter cylindrical member 70 and allows the rotating member 6 to rotate relative to the fixed portion 10.

[0090] In contrast, by rotating the select plate 72, the protrusions constituting the mode select section are moved to a position circumferentially away from the tip of the engagement pin, thereby engaging the engagement pin with the engagement recess. This prevents the inner diameter cylindrical member 71 from rotating relative to the outer diameter cylindrical member 70, and prevents the rotation of the rotating member 6 relative to the fixed portion 10.

[0091] When implementing this disclosure, the braking device is not limited to a braking device that can switch between connected and disconnected states by an actuator, but can employ various conventionally known clutch structures. Specifically, the braking device can also be configured with a one-way clutch including a freewheel.

[0092] In this example, the planetary reduction mechanism 9 includes a sun gear 74, a ring gear 75, a carrier 76, and multiple planetary gears 77. In other words, the planetary reduction mechanism 9 is composed of a single-pinion type planetary gear mechanism.

[0093] The sun gear 74 is connected to the rotating member 6 in a way that enables torque transmission. In this example, the sun gear 74 is located at one end of the rotating member 6 on the axial side.

[0094] The ring gear 75 is positioned coaxially with the sun gear 74 and connected to the input member 4 to enable torque transmission. In this example, the ring gear 75 is located in the axial middle portion of the input member 4.

[0095] The carrier 76 is positioned radially between the sun gear 74 and the ring gear 75, coaxially with the sun gear 74 and the ring gear 75, and is connected to the output member 5 to enable torque transmission.

[0096] Each of the multiple planetary gears 77 meshes with the sun gear 74 and the ring gear 75, and is supported by the carrier 76, enabling it to rotate (spin) around its own central axis.

[0097] When implementing this disclosure, a double-pinion type planetary gear mechanism can be used as the planetary reduction mechanism. Alternatively, the planetary reduction mechanism can be configured as a friction roller mechanism having a sun roller, a ring roller arranged around the sun roller, and a planetary roller arranged radially between the sun roller and the ring roller, with its outer circumferential rolling surface frictionally engaged with the outer circumferential surface of the sun roller and the inner circumferential surface of the ring roller.

[0098] In this example, the two-speed transmission 1 can switch between a low-speed ratio mode, in which the reduction ratio between the input member 4 and the output member 5 is small (the reduction ratio is 1), and a high-speed ratio mode, in which the reduction ratio is larger than that of the low-speed ratio mode, by switching the mode of the electric friction engagement device 7 and the engagement / disengagement state of the braking device 8.

[0099] <Reduced Speed ​​Ratio Mode> To switch the two-speed transmission 1 to the reduced gear ratio mode, the electric friction engagement device 7 is switched to the connected mode, and the braking device 8 is disconnected.

[0100] Specifically, as shown in Figure 2(a), the shift motor 66 rotates the drive cam 34 in the opposite direction to the predetermined direction, that is, in a direction that reduces the amount the rolling element 36 rides up from the bottom of the recess constituting the drive cam surface 48. This releases the force that the driven cam 35 exerts on the piston 32 in one axial direction via the thrust bearing 57 and the pressing member 58.

[0101] When the force pressing the piston 32 in one axial direction is released, the piston 32, thrust bearing 57, and pressing member 58 are pressed in the other axial direction mainly by the elastic restoring force of the first friction plate 30 and elastic member 33, and the piston 32 presses the second friction plate 31, which is closest to the axial direction, in the other axial direction. As a result, the first friction plate 30 and the second friction plate 31 press against each other, and the input member 4 and the rotating member 6 rotate as a single unit. In other words, the electric friction engagement device 7 switches to connection mode. Consequently, the sun gear 74 and the ring gear 75 rotate as a single unit.

[0102] When the drive cam 34 is rotated in the opposite direction to the predetermined direction, the select plate 72 is also rotated in the opposite direction to the predetermined direction. As the select plate 72 rotates, the protrusions constituting the mode select section on the select plate 72 push the engagement pin supported by the outer diameter cylindrical member 70 radially outward, disengaging the engagement pin from the engagement recess on the inner diameter cylindrical member 71.

[0103] This causes the braking device 8 to be disconnected. In other words, rotation of the inner diameter cylindrical member 71 relative to the outer diameter cylindrical member 70 is permitted, and rotation of the rotating member 6 relative to the fixed portion 10 is permitted. As a result, rotation of the sun gear 74 relative to the fixed portion 10 is permitted.

[0104] In the reduced speed ratio mode, the sun gear 74, ring gear 75, and carrier 76 rotate in the same direction and at the same speed, causing the entire planetary reduction mechanism 9 to rotate as a single unit, essentially creating a "glued" state. Therefore, the rotational torque of the input member 4 is transmitted directly to the output member 5 through the path shown by the thick line in Figure 2(a) without being increased (reduced). In other words, in the reduced speed ratio mode, the reduction ratio between the input member 4 and the output member 5 is 1.

[0105] <High reduction ratio mode> To switch the two-speed transmission 1 to the high reduction ratio mode, the electric friction engagement device 7 is switched to the disconnection mode, and the braking device 8 is connected.

[0106] Specifically, as shown in Figure 2(b), the shift motor 66 rotates the drive cam 34 in the predetermined direction, that is, in a direction that increases the amount the rolling element 36 rides up from the bottom of the recess constituting the drive cam surface 48. As a result, the driven cam 35 presses the piston 32 in one axial direction via the thrust bearing 57 and the pressing member 58, elastically reducing the axial dimension of the elastic member 33 and releasing the force that causes the first friction plate 30 and the second friction plate 31 to press against each other.

[0107] As a result, the return spring 78 causes the gap between the first friction plate 30 and the second friction plate 31 to widen, allowing the input member 4 and the rotating member 6 to rotate relative to each other. In other words, the electric friction engagement device 7 switches to the disconnection mode. As a result, the sun gear 74 and the ring gear 75 become able to rotate relative to each other.

[0108] When the drive cam 34 is rotated in the predetermined direction, the select plate 72 is also rotated in the predetermined direction. As the select plate 72 rotates, the protrusions constituting the mode select section on the select plate 72 move to a position away from the tip of the engagement pin supported by the outer diameter cylindrical member 70 in the circumferential direction. As a result, the engagement pin engages with the engagement recess provided on the inner diameter cylindrical member 71, and the braking device 8 is connected. That is, the relative rotation of the rotating member 6 with respect to the fixed part 10 is prevented, and the rotation of the sun gear 74 with respect to the fixed part 10 is prevented.

[0109] In high reduction ratio mode, the rotational torque of the input member 4 is transmitted in the following order through the path shown by the thick line in Figure 2(b): input member 4, ring gear 75, rotational motion of planetary gear 77, revolutionary motion of planetary gear 77 based on meshing with sun gear 74, carrier 76, and output member 5.

[0110] Thus, in the high reduction ratio mode, the rotational torque of the input member 4 is increased by the planetary reduction mechanism 9 and transmitted to the output member 5. The reduction ratio between the input member 4 and the output member 5 in the high reduction ratio mode is determined by the gear ratio of the ring gear 75 and the sun gear 74 (number of teeth of the ring gear 75 / number of teeth of the sun gear 74).

[0111] In this example, the two-speed transmission 1 can switch the reduction ratio between the input member 4 and the output member 5 between two levels, high and low, by switching the mode of the electric friction engagement device 7 and the engagement / disengagement state of the braking device 8. Specifically, in the region where the rotational torque input to the input member 4 is low speed and high torque, the two-speed transmission 1 is switched to the high reduction ratio mode, and in the region where the rotational torque is high speed and low torque, it is switched to the low reduction ratio mode. As a result, the acceleration performance and high-speed performance of electric vehicles and hybrid vehicles when they are running using only the electric motor as the power source can be made close to that of gasoline engine vehicles.

[0112] When switching modes of the two-speed transmission 1, it is not necessary to switch the mode of the electric friction engagement device 7 and the engagement / disengagement state of the braking device 8 perfectly simultaneously; they may be slightly out of order. In other words, the fastening force and timing of the electric friction engagement device 7 and the braking device 8 can be appropriately adjusted to reduce the shift shock associated with switching modes of the two-speed transmission 1.

[0113] In this example, the electric friction engagement device 7 switches from connection mode to disconnection mode, and the piston touch point θ is where the fastening force of the friction engagement portion 26 begins to decrease. p A function to detect the clutch touch point θ where the fastening force becomes 0. f It is equipped with a function to detect [something]. These functions will be explained below using Figures 14(a) to 18.

[0114] Figures 14(a) and 14(b) are diagrams showing the relationship between the rotation angle θ of the drive cam 34 and the output torque T and current value A of the shift motor 66 when switching the electric friction engagement device 7 from connection mode to disconnection mode. Figure 14(a) shows the case when the first friction plate 30 and the second friction plate 31 are new and not worn, while Figure 14(b) shows the case when the first friction plate 30 and the second friction plate 31 have worn down significantly.

[0115] As is clear from Figures 14(a) and 14(b), when the electric friction engagement device 7 switches modes, the output torque T of the shift motor 66 and the current value A of the shift motor 66 change in the same direction. In the electric friction engagement device 7 of this example, the piston touch point θ p and clutch touch point θ f This is detected based on the current value A of the shift motor 66 when the electric friction engagement device 7 is switched from connection mode to disconnection mode.

[0116] When the electric friction engagement device 7 is switched to connection mode, the rolling elements 36 of the cam device 28 are located at the bottom of the recess that constitutes the drive cam surface 48. In this state, as shown in Figure 15, there is a piston clearance C between one axial end of the pressing member 58 and the other axial side of the piston 32. p It exists. This piston clearance C p Based on the presence of [the element], displacement of the piston 32 to the other axial side is permitted.

[0117] Therefore, the force of the elastic member 33 attempting to return to its original shape causes the piston 32 to be elastically pressed to the other axial side, and the piston 32 presses the first friction plate 30 on the far axial side toward the other axial side, causing the first friction plate 30 and the second friction plate 31 to press against each other.

[0118] To switch the electric friction engagement device 7 from the connected mode to the disconnected mode, the drive cam 34 is rotated in the predetermined direction based on energization of the shift motor 66, and the amount of climbing of the rolling element 36 from the bottom of the recess is increased. At this time, the current value A of the shift motor 66 is substantially constant, excluding the temporarily flowing starting current (range α in FIG. 14(a) and FIG. 14(b)).

[0119] By increasing the amount of climbing of the rolling element 36 from the bottom of the recess, when the pressing member 58 is moved toward one axial side, as shown in FIG. 16, an end portion on one axial side of the pressing member 58 contacts another axial side surface of the piston 32. In other words, the piston clearance C p becomes zero.

[0120] From the state shown in FIG. 16, when the drive cam 34 is further rotationally driven in the predetermined direction by the shift motor 66, the piston 32 is pressed toward one axial side against the elastic restoring force of the elastic member 33 by the driven cam 35 via the pressing member 58. In this state, a part of the elastic restoring force of the elastic member 33 is supported by the cam device 28 via the pressing member 58 and the thrust bearing 17, and the remainder is supported by the fixed portion 10 via the friction engagement portion 26 and the braking device 8.

[0121] As the piston 32 is pressed toward one axial side, the force pressing the first friction plate 30 and the second friction plate 31 against each other gradually decreases mainly based on the elastic restoring force of the second friction plate 31 and the elastic member 33. That is, the engagement force of the friction engagement portion 26 gradually decreases.

[0122] While the engagement force of the friction engagement portion 26 is gradually decreased, the current value A of the shift motor 66 increases at a substantially constant increase rate (gradient) (range β in FIG. 14(a) and FIG. 14(b)). That is, the increase rate of the current value A in the range β is larger than the increase rate of the current value A in the range α.

[0123] In the electric friction engagement device 7 of this example, in order to switch the electric friction engagement device 7 from connection mode to disconnection mode, after energizing the shift motor 66, the phase (rotation angle from the reference position (for example, the initial position where the rolling element 36 is located at the bottom of the recess)) θ with respect to the rotation direction of the drive cam 34 when the current value A of the shift motor 66 begins to increase at an increase rate of more than a predetermined first threshold is set to the piston clearance C p The piston touch point θ where becomes 0 p It is detected as such. The first threshold can be determined in advance through experiments or simulations.

[0124] The rate of increase of the current value A is the increase in the current value A per unit rotation angle Δθ of the drive cam 34, ΔA. Note that when the drive cam 34 is rotated in the predetermined direction at a constant rotational speed, the increase in the current value A per unit time, ΔA, can also be used for determination.

[0125] As the fastening force of the friction engagement portion 26 gradually decreases and the fastening force becomes 0, from that moment onward, as shown in Figure 17, a clutch clearance C is created between the axial end of the piston 32 and the first friction plate 30 located on the axial side. f This begins to occur. Clutch clearance C f When this begins to occur, almost all of the elastic restoring force of the elastic member 33 is supported by the cam device 28 via the pressing member 58 and the thrust bearing 57.

[0126] Clutch clearance C f After this phenomenon begins, the current value A of the shift motor 66 increases slowly and logarithmically (range γ in Figures 14(a) and 14(b)). That is, the rate of increase of current value A in range γ is smaller than the rate of increase of current value A in range β.

[0127] In the electric friction engagement device 7 of this example, when switching the electric friction engagement device 7 from connection mode to disconnection mode, the phase of the rotation direction of the drive cam 34 is the piston touch point θ pAfter exceeding a certain threshold, the phase θ with respect to the rotation direction of the drive cam 34 when the rate of increase of the current value A of the shift motor 66 becomes less than or equal to a predetermined second threshold is determined by the clutch clearance C. f The clutch touch point θ where becomes 0 f It is detected as such. Note that the second threshold is smaller than the first threshold. The second threshold can be determined in advance through experiments or simulations.

[0128] The electric friction engagement device 7 in this example is further equipped with a function to detect abnormalities that could lead to failure.

[0129] The electric friction engagement device 7 in this example has a first function for detecting abnormalities, which is to determine whether the wear of the first friction plate 30 and the second friction plate 31 has progressed to the wear limit.

[0130] As the wear of the first friction plate 30 and the second friction plate 31 increases with use of the electric friction engagement device 7, the amount of pressure required by the elastic biasing member 27 to press the first friction plate 30, which is on the axial side, to the other side, for switching the electric friction engagement device 7 to the connection mode, increases. In other words, the amount of pressure required by the cam device 28 to press the piston 32 to one side, for switching the electric friction engagement device 7 to the disconnection mode, decreases.

[0131] As a result, the relationship between the rotation angle θ of the drive cam 34 and the current value A of the shift motor 66 changes from the state shown in Figure 14(a) to the state shown in Figure 14(b). As is clear from Figures 14(a) and 14(b), as the amount of wear on the first friction plate 30 and the second friction plate 31 increases, the piston touch point θ p and clutch touch point θ f It becomes smaller.

[0132] Piston touch point θ p Or clutch touch point θ fHowever, by determining whether it is within a predetermined angular range, it is possible to determine whether the wear of the first friction plate 30 and the second friction plate 31 has progressed to the limit of use. In other words, the piston touch point θ p Or clutch touch point θ f However, the predetermined lower limit θ min The above conditions are met, and the predetermined upper limit value θ is also met. max It has a function to determine that the following conditions are met.

[0133] Lower limit θ min and upper limit θ max Each of these can be determined in advance through experiments or simulations, and the piston touch point θ p and clutch touch point θ f The appropriate setting is determined by which of the following touchpoints is used as the criterion for judgment.

[0134] In this example, the electric friction engagement device 7 has a clutch touch point θ. f By determining whether the angle is within a predetermined range, it is possible to determine whether the wear of the first friction plate 30 and the second friction plate 31 has progressed to the limit of their service life.

[0135] In this example, the electric friction engagement device 7 has a second function for detecting abnormalities: the maximum value A of the current A of the shift motor 66. peak However, it also has a function to determine whether it is within a predetermined range. In other words, the electric friction engagement device 7 determines the maximum value A of the shift motor 66. peak However, the predetermined lower limit A min The above conditions are met, and the predetermined upper limit A is also met. max It has a function to determine that the following conditions are met.

[0136] Lower limit A min and upper limit A max Each of these can be determined in advance through experiments or simulations. In the electric friction engagement device 7 of this example, when the rolling element 36 rides up onto the tip of the protrusion that constitutes the drive cam surface 48, the current value A of the shift motor 66 reaches its maximum value A. peak It will become.

[0137] In the electric friction engagement device 7 of this example, the piston touch point θ p Function to detect clutch touch point θ f The functions for detecting abnormalities and for detecting anomalies are executed according to the flowchart shown in Figure 18.

[0138] First, in S1, it is determined whether the rolling element 36 of the cam device 28 is in its initial position, which is at the bottom of the recess that constitutes the drive cam surface 48. This determination can be made by any method. For example, it can be done based on the output value of a position sensor that detects the axial position of the driven cam 35 or the pressing member 58, or based on the number of rotational pulses generated by a Hall element installed in the shift motor 66.

[0139] If it is determined in S1 that the rolling element 36 is not in its initial position, the process proceeds to S1-1, where the shift motor 66 rotates the drive cam 34 to move the rolling element 36 to its initial position, and then returns to S1.

[0140] If it is determined in S1 that the rolling element 36 is in its initial position, the process proceeds to S2, where the shift motor 66 is energized to start the rotational drive of the drive cam 34 in the predetermined direction. The rotational speed of the drive cam 34 can be any speed.

[0141] In S3, the current value A of the shift motor 66 is monitored, and the rotation angle θ of the drive cam 34 from its initial position when the rate of increase of the current value A exceeds a first threshold is set to the piston touch point θ p It is detected as such.

[0142] In S4, the current value A of the shift motor 66 is monitored, and the rotation angle θ of the drive cam 34 from its initial position when the rate of increase of the current value A falls below the second threshold is set to the clutch touch point θ f It is detected as such.

[0143] In the S5, the clutch touch point θ f Whether it falls within a predetermined angular range, i.e., a predetermined lower limit θ min The above conditions are met, and the predetermined upper limit value θ is also met. max Determine if the following is true: Clutch touch point θ f If the angle does not fall within a predetermined range, i.e., the predetermined lower limit θ min Smaller than or equal to a predetermined upper limit θ max If it is determined to be larger than θ, proceed to S5-1 and clutch touch point θ f It is determined whether the number of anomaly detections i has reached a predetermined number n set in advance.

[0144] Clutch touch point θ f If it is determined that the number of abnormality detections i has not reached a predetermined number n, i.e., is less than n, then in S5-2, 1 is added to i and the process returns to S1.

[0145] In S5-1, the clutch touch point θ f If it is determined that the number of abnormality detections k has reached a predetermined number n, the process proceeds to S5-3, a warning light indicating an abnormality is illuminated, and the process terminates.

[0146] Note that steps S5-1 and S5-2 can be omitted. In this case, in S5, the clutch touch point θ f If it is determined that the angle is not within the specified range, the process proceeds to S5-3, a warning light indicating an abnormality is illuminated, and then the process terminates.

[0147] In S5, the clutch touch point θ f If it is determined that the angle is within a predetermined range, proceed to S6, and the maximum value A of the current A of the shift motor 66 is set. peak Detects.

[0148] In S7, the maximum value is A peak Whether it falls within a predetermined range, i.e., a predetermined lower limit A min The above conditions are met, and the predetermined upper limit A is also met. maxDetermine if it is the following:

[0149] In S7, the maximum value A peak If it does not fall within the predetermined range, i.e., the predetermined lower limit A min Less than or equal to a predetermined upper limit A max If it is determined to be greater than, proceed to S7-1 and the maximum value A peak It determines whether the number of anomaly detections j has reached a predetermined number m set in advance. Maximum value A peak If it is determined that the number of anomaly detections j has not reached a predetermined number m, i.e., is less than m, then in S7-2, 1 is added to j, and the process returns to S1.

[0150] In S7-1, the maximum value A peak If it is determined that the number of abnormality detections j has reached a predetermined number m, the process proceeds to S7-3, a warning light indicating an abnormality is illuminated, and the process terminates.

[0151] In S7, the maximum value A peak If the value is within a predetermined range, it can be determined that there is no abnormality, and in the following S8, it is determined whether the rolling element 36 is in its initial position, which is at the bottom of the recess that constitutes the drive cam surface 48.

[0152] If it is determined in S8 that the rolling element 36 is not in its initial position, the process proceeds to S8-1, where the shift motor 66 rotates the drive cam 34 to move the rolling element 36 to its initial position, and then returns to S8.

[0153] In S8, if it is determined that the rolling element 36 is in its initial position, the process proceeds to termination. Note that S8 and S8-1 can be omitted. In this case, in S7, the maximum value A peak After determining that the value falls within the specified range, the process proceeds to termination.

[0154] According to the electric friction engagement device 7 in this example, the piston touch point θ p and clutch touch point θ fThis can be automatically detected based on the current value A of the shift motor 66. Therefore, the piston touch point θ p and / or clutch touch point θ f This allows for precise control of the electric friction engagement device 7, and the piston touch point θ. p and / or clutch touch point θ f If an abnormality occurs, it can be detected quickly.

[0155] According to the electric friction engagement device 7 in this example, the clutch touch point θ f By determining whether the angle is within a predetermined range, it is possible to determine whether the wear of the first friction plate 30 and the second friction plate 31 has progressed to the limit of their use. Therefore, it is possible to prevent the first friction plate 30 and the second friction plate 31 from being used beyond their respective wear limits, and to reliably prevent seizure at the friction engagement portion 26.

[0156] According to the electric friction engagement device 7 in this example, the maximum value A of the current A of the shift motor 66 peak Whether it falls within a predetermined range, in other words, the maximum value A of the shift motor 66 peak However, the predetermined lower limit A min The above conditions are met, and the predetermined upper limit A is also met. max It is possible to determine whether the following applies.

[0157] If the elastic biasing force of the elastic member 33, which elastically biases the first friction plate 30 and the second friction plate 31 in a direction that causes them to press against each other, is excessively large, or if there is an abnormality such as an improper meshing state between the worm teeth of the worm 68 and the wheel teeth 49 of the drive cam 34, the maximum value A of the shift motor 66 will be affected. peak This becomes excessively large. Conversely, if the elastic restoring force of the elastic member 33 is excessively small, the force pressing the first friction plate 30 and the second friction plate 31 against each other will be insufficient, which may result in an abnormality in which the fastening force of the friction engagement portion 26 cannot be sufficiently secured.

[0158] In this example of the electric friction engagement device 7, the maximum value A of the current A of the shift motor 66 peak Because it has a function to determine whether the value falls within a predetermined range, it can promptly detect the above-mentioned abnormality and reliably prevent the abnormality from inducing further malfunctions.

[0159] When the electric friction engagement device 7 switches modes, the output torque T of the shift motor 66 and the current value A of the shift motor 66 change in the same trend. Therefore, when implementing this disclosure, it is also possible to configure the system to detect the piston touch point, the clutch touch point, and even abnormalities based on the output torque of the shift motor instead of the current value of the shift motor.

[0160] However, if abnormalities are to be detected based on the output torque of the shift motor, torque sensors must be installed on the piston touch point, clutch touch point, and the output shaft of the shift motor.

[0161] In contrast, the electric friction engagement device 7 in this example determines the piston touch point θ based on the current value A of the shift motor 66. p and clutch touch point θ f Furthermore, it detects abnormalities. Therefore, the piston touch point θ p and clutch touch point θ f Furthermore, it eliminates the need to install a torque sensor solely for detecting abnormalities, thereby reducing the cost of the electric friction engagement device 7.

[0162] The operations shown in the flowchart in Figure 18 can be performed at any time as long as they do not interfere with the driving of the vehicle equipped with the two-speed transmission 1. For example, they can be performed immediately after turning the ignition key ON, during kickdown acceleration, or when engine braking is applied, such as when switching the two-speed transmission from the reduced gear ratio mode to the high gear ratio mode.

[0163] However, if the above operation is attempted while the vehicle is in motion, the drive cam 34 cannot be driven at an arbitrary rotational speed, and the clutch touch point θ f or maximum value A peak If an abnormality is detected, returning to S1 to perform a reassessment may cause problems such as the acceleration becoming less smooth. For this reason, it is preferable to perform the above operation while the vehicle is stopped, such as immediately after turning the ignition key ON.

[0164] Each step in the flowchart shown in Figure 18 can be rearranged or performed simultaneously, as long as it does not create a contradiction. For example, steps S4-S5 and S6-S7 can be performed simultaneously while monitoring the current value A of the shift motor 66.

[0165] The two-speed transmission 1 in this example ensures good torque transmission efficiency. The reason for this will be explained next.

[0166] When the cam device 28 generates a pressing force, that is, when the driven cam 35 presses the piston 32 in one axial direction via the thrust bearing 57 and the pressing member 58 (as shown in Figure 2(b)), a force directed in one axial direction is applied to the thrust bearing 57. In addition, the reaction force resulting from the driven cam 35 pressing the piston 32 in one axial direction is applied to the radial bearing 38 in the other axial direction via the rolling elements 36 and the drive cam 34.

[0167] One axial raceway ring 59a of the thrust bearing 57 is supported by the rotating member 6 via a pressing member 58 and a piston 32, while the other axial raceway ring 59b is supported by the fixed portion 10 via a cam device 28, an angular contact ball bearing 39, and a cylindrical member 37. The inner ring 42 of the radial bearing 38 is fitted and fixed to the rotating member 6, while the outer ring 43 is supported by the drive cam 34 of the cam device 28 via a cylindrical member 37 and an angular contact ball bearing 39.

[0168] In the two-speed transmission 1 of this example, when the cam mechanism 28 generates a pressing force, that is, when the piston 32 is pressed toward one side in the axial direction, the axial dimension of the elastic member 33 is elastically reduced, and the force pressing the first friction plate 30 and the second friction plate 31 toward each other is released, and the electric friction engagement device 7 is disconnected, the braking device 8 is connected. In the high reduction ratio mode, when the electric friction engagement device 7 is disconnected and the braking device 8 is connected, the relative rotation of the rotating member 6 with respect to the fixed part 10 is prevented.

[0169] In this state, the axial raceway 59a on one side of the thrust bearing 57 and the axial raceway 59b on the other side do not rotate relative to each other, and the inner ring 42 and outer ring 43 that constitute the radial bearing 38 do not rotate relative to each other. In short, when an axial force (left-right direction in Figure 2(b)) is applied to the thrust bearing 57 and the radial bearing 38, and the rolling resistance increases, the axial raceway 59a on one side of the thrust bearing 57 and the axial raceway 59b on the other side of the thrust bearing 57 do not rotate relative to each other, and the inner ring 42 and outer ring 43 that constitute the radial bearing 38 do not rotate relative to each other.

[0170] Therefore, torque loss in the thrust bearing 57 and radial bearing 38 can be prevented.

[0171] The pressing force generated by the cam device 28 is applied to the rotating member 6 in a uniaxial direction from the driven cam 35 via the pressing member 58, thrust bearing 57, piston 32, and elastic member 33. In contrast, the reaction force associated with the pressing force generated by the cam device 28 is applied to the rotating member 6 in a uniaxial direction from the drive cam 34 via the radial bearing 38. In this way, the axial forces associated with the pressing force generated by the cam device 28 cancel each other out (cancel out) within the rotating member 6.

[0172] On the other hand, when the braking device 8 is disconnected and relative rotation of the rotating member 6 with respect to the fixed portion 10 is permitted (as shown in Figure 2(a)), the electric friction engagement device 7 is connected and the cam device 28 does not generate any pressing force. In this state, since no axial force (left-right direction in Figure 2(a)) is applied to the thrust bearing 57 and radial bearing 38 due to the pressing force generated by the cam device 28, the rolling resistance of the thrust bearing 57 and radial bearing 38 does not become excessively large, and torque loss does not become excessively large.

[0173] In short, in the two-speed transmission 1 of this example, except for the short time during mode switching, the thrust bearing 57 and radial bearing 38 do not rotate under conditions where an axial force is applied due to the pressing force generated by the cam device 28, resulting in increased rolling resistance. Therefore, excessive torque loss in the thrust bearing 57 and radial bearing 38 can be prevented, and the torque transmission efficiency of the two-speed transmission 1 can be ensured to a good degree.

[0174] The friction engagement device of this disclosure is not limited to a two-speed transmission for automobiles, but can be incorporated and used between a pair of rotating members of various structures, or between a rotating member and a stationary member. [Explanation of symbols]

[0175] 1. 2-speed transmission 2. Power source 3 Differential device 4 Input Members 5 Output component 6. Rotating Member 7 Electric friction engagement device 8 Braking device 9. Planetary deceleration mechanism 10 Fixed part 11 Output shaft 12 Drive gears 13 Input Gear 14 output gears 15 Small diameter flange section 16 Flange section 17 Through hole 18 First circular part 19. First cylindrical section 20 Second circular limbus 21 Second cylindrical section 22 Shaft member 23 Stepped cylindrical member 24 Small diameter cylindrical section 25 Female spline section 26 Friction engagement part 27 Elastic biasing member 28 Cam mechanism 29 Electric Actuators 30 1st friction plate 31 2nd friction plate 32 pistons 33 Elastic members 34 Drive Cam 35 Driven cam 36 Rolling element 37 Cylindrical member 38 Radial bearings 39 Angular Contact Ball Bearings 40 Cylindrical section 41 Outward flange section 42 Inner Ring 43 Outer ring 44 Rolling element 45 Inner circle 46 Outer ring 47 balls 48 Drive cam surface 49 Wheel Teeth 50 pin section 51 Female spline section 52 Male spline section 53 Rectangular hole 54a, 54b Support plate part 55 Support hole 56 Support recess 57 Thrust bearing 58 Pressing member 59a, 59b Raceway ring 60 Rolling elements 61 Preload applying means 62 Base 63 Partial cylindrical section 64 Support shaft Around 65 66 Shift motor 67 Reducer 68 Warm 69a, 69b Support bearings 70 Outer diameter cylindrical member 71 Inner diameter cylindrical member 72 Select Plate 73 Outer periphery uneven part 74 Sangiya 75 Ring Gear 76 Careers 77 Planetary Gear 78 Return Spring

Claims

1. First member and A second member is supported coaxially with the first member and capable of relative rotation with respect to the first member, A friction engagement portion having at least one first friction plate and at least one second friction plate, supported to allow relative axial displacement, provided between the first member and the second member, which switches to a state in which torque is transmitted between the first member and the second member by pressing the first friction plate and the second friction plate against each other, and switches to a state in which torque is not transmitted between the first member and the second member by releasing the force pressing the first friction plate and the second friction plate against each other, An elastic biasing member is provided between the first member and the friction engagement portion, and elastically biases the first friction plate and the second friction plate in a direction that causes them to press against each other. A cam device comprising a drive cam supported to allow rotation with respect to the first member and the second member, but unable to be displaced in the axial direction, and a driven cam supported to allow relative rotation and axial displacement with respect to the drive cam, wherein, as the drive cam rotates, the driven cam moves in a direction that increases the axial distance between it and the drive cam, and the elastic biasing member is pressed in a direction that releases the force pressing the first friction plate and the second friction plate against each other, An electric actuator comprising a shift motor and a reduction gear, wherein the shift motor rotates the drive cam via the reduction gear, Equipped with, The function includes detecting the phase relative to the rotational direction of the drive cam when the shift motor rotates the drive cam via the reduction gear to switch the friction engagement portion from a state in which torque is transmitted between the first member and the second member to a state in which torque is not transmitted between the first member and the second member, as the piston touch point at which the elastic biasing member begins to press in a direction that releases the force pressing the first friction plate and the second friction plate against each other, when the output torque or current value of the shift motor begins to increase at an increase rate of 1 or more than a first threshold, and The function includes, when the shift motor rotates the drive cam via the reduction gear to switch the friction engagement portion from a state in which torque is transmitted between the first member and the second member to a state in which torque is not transmitted between the first member and the second member, detecting the phase of the rotation direction of the drive cam when the increase rate becomes less than or equal to a second threshold after passing the piston touch point as the clutch touch point where the force pressing the first friction plate and the second friction plate against each other becomes zero, The function includes determining whether the maximum output torque or current value of the shift motor is within a predetermined range when the shift motor rotates the drive cam via the reduction gear in order to switch the friction engagement portion from a state in which torque is transmitted between the first member and the second member to a state in which torque is not transmitted between the first member and the second member, Equipped with, Electric friction engagement device.

2. The electric friction engagement device according to claim 1, further comprising a function for determining whether the piston touch point or the clutch touch point is within a predetermined angular range.

3. The electric friction engagement device according to claim 1, wherein the elastic biasing member comprises a piston supported to allow axial displacement relative to the first member, and an elastic member provided between the first member and the piston.

4. First member and A second member is supported coaxially with the first member and capable of relative rotation with respect to the first member, A friction engagement portion having at least one first friction plate and one second friction plate supported to allow relative axial displacement, provided between the first member and the second member, which switches to a state in which torque is transmitted between the first member and the second member by pressing the first friction plate and the second friction plate against each other, and switches to a state in which torque is not transmitted between the first member and the second member by releasing the force pressing the first friction plate and the second friction plate against each other, An elastic biasing member is provided between the first member and the friction engagement portion, and elastically biases the first friction plate and the second friction plate in a direction that causes them to press against each other. A cam device comprising a drive cam supported to allow rotation with respect to the first member and the second member, but unable to be displaced in the axial direction, and a driven cam supported to allow relative rotation and axial displacement with respect to the drive cam, wherein, as the drive cam rotates, the driven cam moves in a direction that increases the axial distance between it and the drive cam, and the elastic biasing member is pressed in a direction that releases the force pressing the first friction plate and the second friction plate against each other, An electric actuator comprising a shift motor and a reduction gear, wherein the shift motor rotates the drive cam via the reduction gear, An abnormality detection method for an electric friction engagement device, comprising: In order to switch the friction engagement portion from a state in which torque is transmitted between the first member and the second member to a state in which torque is not transmitted between the first member and the second member, the shift motor rotates the drive cam via the reduction gear, and the phase with respect to the rotation direction of the drive cam when the output torque or current value of the shift motor begins to increase at an increase rate of 1 or more than a first threshold is detected as a piston touch point in which the elastic biasing member begins to be pressed in a direction that releases the force pressing the first friction plate and the second friction plate against each other. In order to switch the friction engagement portion from a state in which torque is transmitted between the first member and the second member to a state in which torque is not transmitted between the first member and the second member, the shift motor rotates the drive cam via the reduction gear, and the phase of the rotation direction of the drive cam after passing the piston touch point and when the increase rate becomes less than or equal to the second threshold is detected as the clutch touch point where the force pressing the first friction plate and the second friction plate against each other becomes zero. A step of determining whether the piston touch point or the clutch touch point is at or above a predetermined angle, The steps include determining whether the maximum output torque or current value of the shift motor is within a predetermined range when the shift motor rotates the drive cam via the reduction gear in order to switch the friction engagement portion from a state in which torque is transmitted between the first member and the second member to a state in which torque is not transmitted between the first member and the second member, Equipped with, Method for detecting abnormalities in an electric friction engagement device.

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