Two-stage transmission, learning method for [mu]-V characteristics of two-stage transmission, and shift control method for two-stage transmission

Abstract

The present invention prevents the occurrence of shift shock in a two-stage transmission capable of switching a reduction ratio between a high stage and a low stage. A two-stage transmission (1) is provided with a learning function that performs mode switching between a first mode and a second mode on the condition that a predetermined learning start condition is satisfied, and in an inertia phase during the mode switching, performs learning on the basis of an output torque of a drive motor (2) and an angular acceleration of an output shaft (11) of the drive motor (2). The friction coefficient between the first friction plate (30) and the second friction plate (31) is calculated, thereby obtaining a [mu]-V characteristic, which is the relationship between the friction coefficient [mu] and a rotation difference (V), which is the difference between the number of rotations of any two of the elements constituting the planetary transmission mechanism (9).

Description

Technical Field

[0001] The present disclosure relates to a two-stage transmission for switching a reduction ratio between an input member and an output member into two stages, a high and a low speed, a learning method of a μ-V characteristic of the two-stage transmission, and a speed change control method of the two-stage transmission. Background Art

[0002] In recent years, due to the trend of reducing the consumption of fossil fuels, research on electric vehicles and hybrid vehicles is being carried out and some of them are being implemented. The electric motor, which is the power source of electric vehicles and hybrid vehicles, is different from the internal combustion engine (engine) that operates by directly burning fossil fuels. The characteristics of the torque and rotation speed of the output shaft are preferably used for automobiles, that is, generally, the maximum torque is generated at the time of starting, so it is not necessarily necessary to set a transmission like a general automobile with an internal combustion engine as the driving source.

[0003] However, even when an electric motor is used as the driving source, the acceleration performance and high-speed performance can be improved by providing a transmission. Specifically, by providing a transmission, the relationship between the vehicle's running speed and acceleration can be made smoother, similar to that of a car equipped with a gasoline engine and having a transmission in the power transmission system. Fig.41 Provide explanation.

[0004] For example, if a power transmission device with a large reduction ratio is arranged between the output shaft of the electric motor and the input part of the differential gear connected to the drive wheels, the relationship between the acceleration (G) and the driving speed (km / h) of the electric vehicle becomes Fig.41 That is, the acceleration performance at low speed is excellent, but it cannot travel at high speed. In contrast, if a power transmission device with a small reduction ratio is arranged between the output shaft and the input part, the relationship becomes Fig.41 That is, the vehicle can travel at high speed, but the acceleration performance at low speed is impaired.

[0005] On the other hand, if a transmission is provided between the output shaft and the input part, and the reduction ratio of the transmission is changed according to the vehicle speed, a characteristic is obtained in which the part on the left side of the solid line a and the part on the right side of the dotted line b are continuous. Fig.41 The gasoline engine vehicle with the same output as shown by the dotted line c is roughly the same, and regarding the acceleration performance and high-speed performance, it can be clearly seen that the same performance as a gasoline engine vehicle with a transmission provided in the power transmission system can be obtained.

[0006] Japanese Patent Laid-Open No. 05-116549 discloses a structure of an electric vehicle drive device in which the torque of the output shaft of the electric motor is increased by a two-stage transmission composed of a pair of planetary gear mechanisms and a pair of brakes and transmitted to a differential gear. In the electric vehicle drive device, the speed reduction ratio between the output shaft of the electric motor and the differential gear can be switched between high and low stages by switching the connected state and disconnected state of the pair of brakes to switch the components of the pair of planetary gear mechanisms between a state in which they can rotate and a state in which they cannot rotate.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 05-116549 Summary of the invention

[0010] Problems to be solved by the invention

[0011] In automobiles including electric vehicles, it is important to prevent the occurrence of shock (speed change shock) when switching the reduction ratio in order to ensure ride comfort performance, etc. In the electric vehicle drive device described in Japanese Patent Laid-Open No. 05-116549, if the timing of switching the connection state and disconnection state of a pair of brakes and the output torque and rotation number of the motor as a drive source are properly controlled, and the torque transmitted to each brake is adjusted, the reduction ratio can be switched while maintaining the rotation torque of the output shaft constant, and the occurrence of speed change shock can be prevented.

[0012] Here, the torque transmitted to the brake can be calculated based on the relative rotation number (relative rotation speed) of the friction engagement elements, that is, the dependence of the friction coefficient on the sliding speed (μ-V characteristics) and the force pressing the friction engagement elements. The friction coefficient between the friction engagement elements of the brake changes with changes in the use environment, annual degradation, etc., and thus, as shown in FIG. Fig.42 Therefore, if the μ-V characteristic changes with age-related degradation and changes in the external environment, the torque transmitted to the brake cannot be estimated with high accuracy when switching the reduction ratio, which may cause a speed change shock.

[0013] In view of the above, the present disclosure aims to prevent the occurrence of speed change shock regardless of changes in the use environment, annual degradation, etc., in a two-stage transmission capable of switching the reduction ratio to two stages, high and low, by realizing a structure capable of learning the above-mentioned μ-V characteristics that change with use.

[0014] Solutions to Solve Problems

[0015] One aspect of the present disclosure relates to a two-stage transmission. The two-stage transmission of one aspect of the present disclosure includes a planetary speed change mechanism, an input member, an output member, a drive motor, a rotation transmission state switching device, and a friction engagement device.

[0016] The planetary speed change mechanism includes an input element connected to the input member, an output element connected to the output member and rotatable relative to the input element, and a rotating element rotatable relative to the input element and the output element.

[0017] The planetary speed change mechanism comprises a sun element, a ring element supported around the sun element so as to be able to rotate relative to the sun element, a carrier element supported so as to be able to rotate relative to the sun element and the ring element, and a plurality of planetary elements engaged so as to be able to transmit torque to the sun element and the ring element and rotatably supported on the carrier element.

[0018] The input element is composed of any one of the sun element, the ring element, and the carrier element.

[0019] The output element is any one of the sun element, the ring element, and the carrier element, and is composed of an element different from the input element.

[0020] The rotating element is composed of the remaining elements of the sun element, the ring element, and the carrier element except the input element and the output element.

[0021] The drive motor rotationally drives the input member directly or via a speed reducer.

[0022] The rotation transmission state switching device is arranged between the rotating element and a fixed part which does not rotate during use, and switches between a free mode in which the rotating element can rotate relative to the fixed part and a locked mode in which the rotating element cannot rotate.

[0023] The friction engagement device comprises at least one first friction plate and at least one second friction plate supported in a manner capable of axial relative displacement, and are arranged between any two elements among the sun element, the ring element, and the carrier element. By pushing the first friction plate and the second friction plate against each other, a connection mode is switched to in which the any two elements rotate as a whole. And by releasing the force pushing the first friction plate and the second friction plate against each other, a disconnection mode is switched to in which the any two elements rotate relative to each other.

[0024] The two-stage transmission includes a first mode in which the rotation transmission state switching device is set to the free mode and the friction engagement device is set to the connected mode, and a second mode in which the rotation transmission state switching device is set to the locked mode and the friction engagement device is set to the disconnected mode.

[0025] The two-stage transmission has the following learning function: mode switching is implemented between the first mode and the second mode under the condition of satisfying a predetermined learning start condition, and in the inertia stage of the mode switching, the friction coefficient between the first friction plate and the second friction plate is calculated based on the output torque of the drive motor and the angular acceleration of the output shaft of the drive motor, thereby obtaining a μ-V characteristic which is the relationship between the friction coefficient and the difference in the number of rotations between any two of the above elements, that is, the rotation difference.

[0026] In a two-stage transmission of one embodiment of the present invention, when executing the above-mentioned learning function, the rotation number of the output shaft of the above-mentioned drive motor is set to be constant, and after starting the mode switching between the above-mentioned first mode and the above-mentioned second mode, it is determined that the above-mentioned inertia stage has started, based on the condition that the change per unit time of the above-mentioned rotation difference exceeds a predetermined threshold value.

[0027] A two-stage transmission of one embodiment of the present invention has the following control function: when switching the mode between the first mode and the second mode, based on the μ-V characteristic obtained according to the learning function, the output torque of the drive motor and the magnitude of the force pushing the first friction plate and the second friction plate against each other are controlled.

[0028] In the two-stage transmission according to one aspect of the present disclosure, the friction engagement device may include an elastic urging member, a cam device, and an electric actuator.

[0029] The elastic urging member elastically urges the first friction plate and the second friction plate in a direction of pressing the first friction plate and the second friction plate against each other.

[0030] The cam device comprises a driving cam and a driven cam supported in a manner capable of relative rotation and axial relative displacement relative to the driving cam. The cam device relatively displaces the driven cam in a direction in which the axial interval between the driven cam and the driving cam is enlarged as the driving cam rotates, thereby pressing the elastic force applying member in a direction in which the force pressing the first friction plate and the second friction plate against each other is released.

[0031] The electric actuator includes a shift motor and a shift speed reducer, and the drive cam is rotationally driven by the shift motor via the shift speed reducer.

[0032] In the two-stage transmission according to one aspect of the present disclosure, the friction engagement device includes a return spring that elastically urges the first friction plate and the second friction plate in a direction in which they are separated from each other.

[0033] In a two-stage transmission of one embodiment of the present invention, the above-mentioned rotation transmission state switching device has a one-way clutch mode, which is a mode that only allows the above-mentioned rotating element to rotate in a predetermined direction relative to the above-mentioned fixed part, and prevents the above-mentioned rotating element from rotating in a direction opposite to the above-mentioned predetermined direction relative to the above-mentioned fixed part.

[0034] In this case, the function of setting the rotation transmission state switching device to the one-way clutch mode may be provided while the friction engagement device is switched from the disconnecting mode to the connecting mode and / or while the friction engagement device is switched from the connecting mode to the disconnecting mode.

[0035] One scheme of the present disclosure relates to a method for learning a μ-V characteristic in the two-stage transmission, which is a relationship between the friction coefficient between the first friction plate and the second friction plate and the difference in the number of rotations of any two elements, i.e., the rotation difference. The method for learning the μ-V characteristic of the two-stage transmission implements mode switching between the first mode and the second mode on the condition that a predetermined learning start condition is satisfied, and in the inertia phase of the mode switching, the friction coefficient is calculated based on the output torque of the drive motor and the angular acceleration of the output shaft of the drive motor, thereby obtaining the μ-V characteristic.

[0036] One solution of the present disclosure relates to a speed control method of the above-mentioned two-stage transmission. The speed control method comprises the following steps:

[0037] According to the above μ-V characteristic learning method, the above μ-V characteristic learning steps are obtained; and

[0038] When switching between the first mode and the second mode, based on the μ-V characteristic obtained in the learning step, the output torque of the drive motor and the magnitude of the force pressing the first friction plate and the second friction plate against each other are controlled.

[0039] The present disclosure can be implemented by appropriately combining the above-mentioned various aspects unless conflicts arise.

[0040] Effects of the Invention

[0041] According to a two-stage transmission, a method for learning the μ-V characteristics of the two-stage transmission, and a speed change control method of the two-stage transmission according to one scheme of the present disclosure, since the μ-V characteristics that change with use can be learned, a two-stage transmission is provided that can prevent the occurrence of speed change shock regardless of changes in the use environment, annual degradation, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a cross-sectional view schematically showing a drive train in which a two-stage transmission according to a first example of an embodiment of the present disclosure is incorporated.

[0043] Figure 2 (a) is a diagram showing a torque transmission path in a low reduction ratio mode of a two-stage transmission according to a first example, Figure 2 (b) is a diagram showing a torque transmission path in a high reduction ratio mode of the two-stage transmission of the first example.

[0044] Figure 3 It is a perspective view of the two-stage transmission of the first example.

[0045] Figure 4 It is a cross-sectional view of the two-stage transmission of the first example.

[0046] Figure 5 This is a perspective view showing the two-stage transmission of the first example with the planetary speed change mechanism removed.

[0047] Figure 6 This is a cross-sectional view showing the two-stage transmission of the first example with the planetary speed change mechanism removed.

[0048] Figure 7 It is an exploded perspective view of the two-stage transmission of the first example.

[0049] Figure 8 This is an exploded perspective view showing a worm gear and two support bearings removed from the friction engagement device constituting the two-stage transmission of the first example.

[0050] Fig. 9 It is an exploded perspective view showing a first friction plate and a second friction plate removed from the friction engagement device.

[0051] Fig.10 yes Figure 4 Magnified view of the X section.

[0052] Fig.11 This is a perspective view showing a driving cam removed from the friction engagement device.

[0053] Fig.12 This is an exploded perspective view showing a driven cam and rolling elements removed from the friction engagement device.

[0054] Fig.13 (a) is a perspective view showing a flange portion and a pressing member of a rotating member removed from the two-stage transmission of the first example, Fig.13 (b) is an exploded perspective view showing the flange portion and the pressing member of the rotating member removed.

[0055] Fig.14 (A)~ Fig.14 (D) is a schematic diagram of the cam device of the friction engagement device as viewed from the radially outer side.

[0056] Fig.15 This is a perspective view of the rotation transmission state switching device constituting the two-stage transmission of the first example, as viewed from the other axial side.

[0057] Fig.16 It is an exploded perspective view of the above-mentioned rotation transmission state switching device.

[0058] Fig.17 This is an end view of the rotation transmission state switching device viewed from the other axial side with the selection plate removed.

[0059] Fig.18 yes Fig.17 Enlarged view of the Y part.

[0060] Fig.19 (A) is a schematic diagram of the rotation transmission state switching device, showing the engagement relationship between the first engagement claw and the second engagement claw, the engagement recess, and the protrusion in the free mode. Fig.19 (B) is a schematic diagram showing the above-mentioned engagement relationship in the locking mode, Fig.19 (C) is a schematic diagram showing the above-mentioned engagement relationship in the one-way clutch mode.

[0061] Fig. 20 It is a diagram schematically showing the modes of the friction engagement device and the modes of the rotation transmission state switching device in the two-stage transmission of the first example.

[0062] Fig.21 (a) and Fig.21 (b) is a graph showing the relationship between the rotation angle of the drive cam and the output torque and current value of the shift motor when the friction engagement device is switched from the connection mode to the disconnection mode. Fig.21 (a) is a diagram showing the first friction plate and the second friction plate when they are new and unworn. Fig.21 (b) is a diagram showing a case where the wear of the first friction plate and the second friction plate has progressed significantly.

[0063] Fig. 22 It is a cross-sectional view showing a state in which the friction engagement device is switched to a connection mode.

[0064] Fig.23 This is a cross-sectional view showing a state in which the pressing member and the piston are in contact during the switching process from the connection mode to the disconnection mode of the friction engagement device.

[0065] Fig.24 It is a cross-sectional view showing a state in which the friction engagement device is switched to the cut-off mode.

[0066] Fig.25 This is a flowchart showing the operation when the two-speed transmission of the first example is switched from the high speed reduction ratio mode to the low speed reduction ratio mode.

[0067] Fig.26 1 is a line graph showing time changes of various parameters when the two-speed transmission of the first example is switched from a high speed reduction ratio mode to a low speed reduction ratio mode.

[0068] Fig. 27 This is a cross-sectional view showing a part of a two-stage transmission according to a comparative example.

[0069] Fig.28 This is a diagram schematically showing the connected state and disconnected state of the first friction engagement device and the second friction engagement device in a two-stage transmission of a comparative example.

[0070] Fig.29 The two-stage transmission of the modified example of the first example is equivalent to Fig. 20 .

[0071] Fig.30 It is a schematic diagram showing a two-stage transmission according to a second example of an embodiment of the present invention.

[0072] Fig.31 It is a schematic diagram showing a two-stage transmission according to a third example of an embodiment of the present invention.

[0073] Fig.32 It is a schematic diagram showing a two-stage transmission according to a fourth example of an embodiment of the present invention.

[0074] Fig.33 It is a schematic diagram showing a two-stage transmission according to a fifth example of the embodiment of the present invention.

[0075] Fig.34 It is a schematic diagram showing a two-stage transmission according to a sixth example of an embodiment of the present invention.

[0076] Fig.35 It is a schematic diagram showing a two-stage transmission according to a seventh example of an embodiment of the present invention.

[0077] Fig.36 It is a schematic diagram showing a two-stage transmission according to an eighth example of an embodiment of the present invention.

[0078] Fig.37It is a schematic diagram showing a two-stage transmission according to a ninth example of an embodiment of the present invention.

[0079] Fig.38 It is a schematic diagram showing a two-stage transmission according to a tenth example of an embodiment of the present invention.

[0080] Fig.39 It is a schematic diagram showing a two-stage transmission according to an eleventh example of an embodiment of the present invention.

[0081] Fig.40 It is a schematic diagram showing a two-stage transmission according to a twelfth example of an embodiment of the present invention.

[0082] Fig.41 This is a diagram for explaining the effect of incorporating a transmission into a drive device using an electric motor as a drive source.

[0083] Fig.42 It is a line graph showing μ-V characteristics. DETAILED DESCRIPTION

[0084] [First example]

[0085] use Figure 1 to Figure 26 A first example of the embodiment of the present disclosure will be described. A two-stage transmission 1 of this example increases the output torque of a drive motor 2 as a drive source, and transmits the output torque to a differential device 3 as it is, even if the rotation is reduced or not increased.

[0086] exist Figure 1-2 In (b), in order to facilitate understanding of the present invention, the elements constituting the two-stage transmission 1 and the differential device 3 are schematically shown.

[0087] The two-stage transmission 1 of this example includes a drive motor 2 , an input member 4 , an output member 5 , a friction engagement device 7 , a rotation transmission state switching device 8 , and a planetary speed change mechanism 9 .

[0088] The input member 4 is composed of a housing or the like that houses the two-stage transmission 1, and is rotatably supported by a rolling bearing or the like (not shown) relative to a fixed portion 10 that does not rotate during use. In this example, the input member 4 is configured to be cylindrical (hollow). In addition, the input member 4 is axially one-sided ( Figure 1 An input gear 13 is provided at the end portion (on the right side) and the input gear 13 meshes with a drive gear 12 provided on the output shaft 11 of the drive motor 2.

[0089] The output member 5 is coaxial with the input member 4 and supported in a manner that allows relative rotation with respect to the input member 4. In this example, the output member 5 is supported on the radially inner side of the cylindrical input member 4 via a rolling bearing (not shown) and the like so as to allow relative rotation with respect to the input member 4. In addition, the output member 5 has an output gear 14 at one end on the axial side. The output gear 14 meshes with a gear provided on the input portion of the differential device 3. The output member 5 drives the input portion of the differential device 3 to rotate.

[0090] The drive motor 2 rotationally drives the input member 4 via a gear-type speed reducer composed of a drive gear 12 and an input gear 13 .

[0091] The planetary speed change mechanism 9 includes an input element connected to the input member 4 , an output element connected to the output member 5 and rotatable relative to the input element, and a rotating element rotatable relative to the input element and the output element.

[0092] The planetary speed change mechanism 9 includes a sun element, a ring element supported around the sun element in a manner capable of relative rotation relative to the sun element; a carrier element supported in a manner capable of relative rotation relative to the sun element and the ring element; and a plurality of planetary elements engaged in a manner capable of transmitting torque to the sun element and the ring element and rotatably supported on the carrier element.

[0093] The input element is composed of any one of the sun element, the ring element, and the carrier element.

[0094] The output element is any one of the sun element, the ring element, and the carrier element, and is composed of an element different from the input element.

[0095] The rotating element is composed of the remaining elements of the sun element, the ring element, and the carrier element except the input element and the output element.

[0096] In this example, the planetary speed change mechanism 9 is composed of a planetary gear mechanism in which gears are meshed with each other. That is, the sun element is composed of a sun gear 101, the ring element is composed of a ring gear 102, the carrier element is composed of a carrier 103, and the plurality of planetary elements are composed of a plurality of planetary gears 104. Therefore, the plurality of planetary gears 104 of the planetary speed change mechanism 9 are each composed of a single pinion type planetary gear mechanism meshed with both the sun gear 101 and the ring gear 102.

[0097] In the case of implementing the present disclosure, a double pinion type planetary gear mechanism can be used as a planetary reduction mechanism. Alternatively, a planetary roller mechanism can be used as a planetary speed change mechanism. In this case, the sun element is composed of a sun roller, the ring element is composed of an annular roller, and the plurality of planetary elements are composed of a plurality of planetary rollers.

[0098] In this example, the sun gear 101 is provided at one end portion of the rotating member 6 in the axial direction.

[0099] The rotating member 6 is supported coaxially with the input member 4 and the output member 5 and is rotatable relative to the input member 4 and the output member 5. More specifically, the rotating member 6 is supported rotatably relative to the fixed portion 10 via the rotation transmission state switching device 8, the cam device 28 constituting the friction engagement device 7, and a radial bearing 38 for supporting the driving cam 34 constituting the cam device 28 so as to be rotatable relative to the rotating member 6.

[0100] The rotating member 6 has a small-diameter flange portion 15 protruding radially outward at an axially intermediate portion, and a small-diameter flange portion 15 located on the other axial side ( Figure 1 The portion (on the left side) has a flange portion 16 protruding radially outward.

[0101] The flange portion 16 includes: a first circular portion 18 in the shape of a hollow circular plate; a first cylindrical portion 19 bent from the radially outer end of the first circular portion 18 toward the other axial side; a second circular portion 20 in the shape of a hollow circular plate bent from the axially other end of the first cylindrical portion 19 toward the radially outer side; and a second cylindrical portion 21 bent from the radially outer end of the second circular portion 20 toward the other axial side. The first circular portion 18 has partially arc-shaped through holes 17 at multiple locations in the radially intermediate portion for inserting the partial cylindrical portion 63 of the pressing member 58 constituting the friction engagement device 7.

[0102] In this example, the rotating member 6 is connected to the shaft member 22 having the small diameter flange portion 15. Fig.13 (b) is formed by externally fitting and fixing a stepped cylindrical member 23. That is, the stepped cylindrical member 23 has a flange portion 16 and a small-diameter cylindrical portion 24 bent from the radially inner end of the first circular portion 18 of the flange portion 16 toward the other axial side. The female spline portion 25 provided on the inner circumference of the small-diameter cylindrical portion 24 is spline-engaged with the male spline portion provided on the outer circumference of the shaft member 22, thereby supporting and fixing the stepped cylindrical member 23 to the shaft member 22. However, the rotating member can also be formed by combining and fixing the stepped cylindrical member and the shaft member by press-fitting, welding, etc.

[0103] In this example, the above-mentioned rotating element is constituted by a sun gear 101 .

[0104] The ring gear 102 is coaxially disposed around the sun gear 101 and is connected so as to transmit torque to the input member 4. In this example, the ring gear 102 is provided at an axially intermediate portion of the input member 4.

[0105] In this example, the input element is constituted by a ring gear 102 .

[0106] The carrier 103 is disposed coaxially with the sun gear 101 and the ring gear 102 in the radial direction and is connected between the sun gear 101 and the ring gear 102 so as to transmit torque to the output member 5 .

[0107] In this example, the output element is composed of a carrier 103 .

[0108] The plurality of planetary gears 104 mesh with the sun gear 101 and the ring gear 102. The plurality of planetary gears 104 are supported on the carrier 103 so as to be rotatable (rotatable) about their own central axes.

[0109] The rotation transmission state switching device 8 is arranged between the above-mentioned rotating element (in this case, the sun gear 101) and the fixed part 10 which does not rotate during use, and switches the sun gear 101 as the above-mentioned rotating element into a free mode in which it can rotate relative to the fixed part 10 and a locked mode in which it cannot rotate.

[0110] In this example, if Figure 15 to Figure 18 As shown, the rotation transmission state switching device 8 includes a first member 71 and a second member 72 that are coaxially arranged with each other, and a mode selection member 73 that rotates in accordance with the rotation of the drive cam 34 .

[0111] The first member 71 is connected to the sun gear 101 in a manner capable of transmitting torque, and the second member 72 is supported and fixed to the fixed portion 10. The rotation transmission state switching device 8 of this example has a one-way clutch mode in addition to a free mode and a lock mode. The free mode is a mode that allows the first member 71 to rotate relative to the fixed portion 10 regardless of the rotation direction of the first member 71, the lock mode is a mode that prevents the first member 71 from rotating relative to the fixed portion 10 regardless of the rotation direction of the first member 71, and the one-way clutch mode is a mode that allows only the rotation of the first member 71 in a predetermined direction. Specifically, the rotation transmission state switching device 8 of this example switches between the free mode, the lock mode, and the one-way clutch mode based on the rotation of the mode selection member 73.

[0112] The first component 71 has a gear-shaped concavo-convex portion 76 on the outer circumferential surface, and the gear-shaped concavo-convex portion 76 is formed by alternately arranging the engaging concave portions 74 and the convex portions 75 in the circumferential direction. The first component 71 has an outer diameter side concavo-convex engaging portion 77 on the inner circumferential surface, and the outer diameter side concavo-convex engaging portion 77 is formed by alternately arranging the concave portions and the convex portions in the circumferential direction. The first component 71 is supported so as to be non-rotatable relative to the rotating component 6 by engaging the outer diameter side concavo-convex engaging portion 77 with the inner diameter side concavo-convex engaging portion 78 provided on the outer circumferential surface of the second cylindrical portion 21 of the rotating component 6, and rotates integrally with the rotating component 6 and the sun gear 101.

[0113] The second component 72 is coaxial with the first component 71 and supported around the first component 71 so as to be relatively rotatable relative to the first component 71. The inner circumferential surface of the second component 72 faces the front end surface of the convex portion 75 of the first component 71 with a gap therebetween. The second component 72 has an inner diameter side concave-convex engagement portion 79 on the outer circumferential surface, and the inner diameter side concave-convex engagement portion 79 is formed by alternately arranging concave portions and convex portions in the circumferential direction. The second component 72 is supported so as to be non-rotatable relative to the fixed portion 10 by engaging the inner diameter side concave-convex engagement portion 79 with the outer diameter side concave-convex engagement portion provided on the inner circumferential surface of the fixed portion 10.

[0114] The second member 72 includes a base portion 80 having a rectangular cross-sectional shape and a cylindrical portion 81 that protrudes from a radially outer end portion of one axial side surface of the base portion 80 over the entire circumference toward one axial side.

[0115] The base portion 80 has a plurality of (six each in the example shown in the figure) first holding recessed portions 82 and second holding recessed portions 83 that are alternately arranged in the circumferential direction.

[0116] Each first holding recess 82 opens to the inner peripheral surface of the base 80 and the other axial side surface. The first holding recess 82 includes a spring holding portion 84a and a pedestal portion 85a. When viewed from the other axial side, the spring holding portion 84a has a portion that is closer to one side ( Figure 17 to Figure 19 The pedestal portion 85a has a generally circular opening shape when viewed from the other axial side, and is aligned with the other circumferential side (the front side in the clockwise direction of the spring retaining portion 84a) of the spring retaining portion 84a. Figure 17 to Figure 19 The rear side in the clockwise direction is arranged adjacent to each other.

[0117] Each second holding recess 83 is open to the inner peripheral surface and the other axial side surface of the base 80, and has a spring holding portion 84b and a seat portion 85b. When viewed from the other axial side, the second holding recess 83 has a shape symmetrical to the first holding recess 82 about an imaginary plane containing the central axis of the second component 72.

[0118] In order to realize the free mode, the locking mode and the one-way clutch mode, the rotation transmission state switching device 8 has a first claw member 86 and a second claw member 87, and a first claw force member 88 and a second claw force member 89 between the first member 71 and the second member 72. In this example, the number of the first claw member 86, the second claw member 87, the first claw force member 88, and the second claw force member 89 is multiple and the number is the same.

[0119] Each of the first claw members 86 includes a first base portion 90 and a first engaging claw 91 .

[0120] The first base portion 90 is configured in a substantially cylindrical shape, and is supported (pivotally supported) on the pedestal portion 85 a of the first holding recess 82 so as to be able to swing about a pivot axis parallel to the central axis of the second member 72 .

[0121] The first engaging claw 91 is formed in a substantially flat plate shape and extends toward one side in the circumferential direction from the first base portion 90. The first engaging claw 91 has its other axial side portion facing (engaged with) the outer circumferential surface of the annular convex portion 92 of the mode selection member 73, and has its one axial side portion facing the concave-convex portion 76 of the first member 71 (engaged in a manner that enables engagement and disengagement with respect to the engaging concave portion 74).

[0122] Each second claw member 87 includes a second base portion 93 swingably supported on the pedestal portion 85b of the second holding recess 83, and a second engaging claw 94 extending toward the other side in the circumferential direction from the second base portion 93. When viewed from the other side in the axial direction, the second claw member 87 has a shape symmetrical to the first engaging claw 91 with respect to an imaginary plane including the central axis of the second member 72, and is arranged symmetrically to the first engaging claw 91.

[0123] The first claw urging member 88 elastically urges the first claw member 86 in a direction in which the first engaging claw 91 is engaged with the engaging recess 74 of the first member 71. That is, the first claw urging member 88 urges the first claw member 86 in a direction in which the first claw member 86 is engaged with the engaging recess 74 of the first member 71. Fig.18 Specifically, the first claw force member 88 is composed of an elastic member such as a coil spring, and is held in an elastically compressed state between the bottom surface (the surface facing radially inward) of the spring retaining portion 84a of the first retaining recess 82 and the radially outer surface of the first engaging claw 91.

[0124] The second claw urging member 89 is composed of the same elastic member as the first claw urging member 88, and is symmetrically arranged with respect to the first claw urging member 88 with respect to an imaginary plane including the central axis of the second member 72 when viewed from the other axial side. That is, the second claw urging member 89 is held in an elastically compressed state between the bottom surface of the spring holding portion 84b of the second holding recess 83 and the radially outer side surface of the second engaging claw 94, and elastically urges the second engaging claw 94 of the second claw member 87 in a direction in which the second engaging claw 94 is engaged with the engaging recess 74 of the first member 71.

[0125] like Fig.16 As shown, the mode selection member 73 includes a substantially circular plate-shaped base portion 95 and an annular protrusion 92 that protrudes from a radially intermediate portion of the other axial side surface of the base portion 95 over the entire circumference toward the other axial side.

[0126] The base 95 has plate-side engaging holes 96 at multiple locations (three locations in the illustrated example) at equal intervals in the circumferential direction of the radially intermediate portion of the other axial side surface. The end portion of the pin portion 50 on one axial side is fitted (engaged) in each plate-side engaging hole 96 without play. That is, the mode selection member 73 rotates integrally (in the same direction and at the same speed) with the drive cam 34.

[0127] The annular convex portion 92 has protrusions 97 protruding radially outward at a plurality of locations in the circumferential direction of the outer circumferential surface. That is, the annular convex portion 92 has gear-shaped concave-convex portions 98 formed by alternately arranging the protrusions 97 and concave portions in the circumferential direction on the outer circumferential surface.

[0128] The first member 71 and the second member 72 are combined with the mode selection member 73 to be relatively rotatable via the cover 99 and the retaining ring 100 and to be non-displaceable in the axial direction (not accidentally separated in the axial direction), thereby constituting the rotation transmission state switching device 8 .

[0129] In a state where the first component 71 is arranged radially inside the axial one-side portion of the base 80 of the second component 72, the circular cover body 99 is supported and fixed to the axial one-side surface of the second component 72 by screwing, and the other axial side surface of the radial inner portion of the cover body 99 is opposed to the axial one-side surface of the first component 71. Thus, the displacement of the first component 71 to the axial one-side relative to the second component 72 can be prevented.

[0130] The annular protrusion 92 of the mode selection member 73 is arranged radially inside the axially other side portion of the base portion 80 of the second member 72, the front end surface (one axial side surface) of the annular protrusion 92 is in sliding contact with or nearly opposite to the axially other side surface of the first member 71, and the axially one side surface of the radially outer portion of the base portion 95 is in sliding contact with or nearly opposite to the axially other side surface of the base portion 80 of the second member 72, and the retaining ring 100 is locked to the axially other side end portion of the inner circumferential surface of the cylindrical portion 81 of the second member 72. Thus, displacement of the first member 71 and the mode selection member 73 to the axially other side relative to the second member 72 can be prevented.

[0131] The rotation transmission state switching device 8 is constructed to switch the engagement state of the first engagement claw 91 of the first claw component 86 and the engagement recess 74 of the first component 71, and the engagement state of the second engagement claw 94 of the second claw component 87 and the engagement recess 74 based on the rotation of the mode selection component 73, thereby being able to switch between the free mode, the locking mode and the one-way clutch mode.

[0132] <Free Mode>

[0133] In the free mode, the phase of the mode selection component 73 relative to the circumferential direction of the second component 72 is adjusted, such as Fig.19 As shown in (A), the first engaging claw 91 is lifted radially outward against the elastic force of the first claw urging member 88 by the protruding portion 97, and the second engaging claw 94 is lifted radially outward against the elastic force of the second claw urging member 89.

[0134] As a result, the engagement between the engagement recess 74 of the first member 71 and the first engagement claw 91 and the second engagement claw 94 is disengaged. In this state, the first member 71 is allowed to rotate relative to the second member 72 regardless of the relative rotation direction of the first member 71 and the second member 72. In other words, the first member 71 is allowed to rotate relative to the fixed portion 10 regardless of the rotation direction of the first member 71.

[0135] <Lock Mode>

[0136] In the locking mode, the phase of the mode selection component 73 relative to the circumferential direction of the second component 72 is adjusted, such as Fig.19 As shown in (B), the protrusion 97 is located at a portion offset in the circumferential direction from the first engagement claw 91 of the first claw member 86 and the second engagement claw 94 of the second claw member 87. That is, the concave portion of the concave-convex portion 98 is aligned with the first engagement claw 91 and the second engagement claw 94 in the circumferential direction.

[0137] As a result, the engagement recess 74 of the first member 71 engages with the first engagement claw 91 and the second engagement claw 94. In this state, the first member 71 is prevented from rotating relative to the second member 72 regardless of the relative rotation direction of the first member 71 and the second member 72. In other words, the first member 71 is prevented from rotating relative to the fixed portion 10 regardless of the rotation direction of the first member 71.

[0138] <One-way clutch mode>

[0139] In the one-way clutch mode, the phase of the mode selection component 73 relative to the circumferential direction of the second component 72 is adjusted, such as Fig.19 As shown in FIG. 5C , the second engaging claw 94 is lifted radially outward by the protruding portion 97 only against the elastic force of the second claw urging member 89 .

[0140] As a result, the engagement recess 74 of the first member 71 is engaged with the first engagement claw 91, and the engagement between the engagement recess 74 and the second engagement claw 94 is released. In this state, only the first member 71 is allowed to move relative to the second member 72 in the above-mentioned predetermined direction ( Fig.19 (C) clockwise) and prevents rotation in the direction opposite to the predetermined direction ( Fig.19 (C) Counterclockwise rotation.

[0141] That is, if the first component 71 is to rotate relative to the second component 72 in the predetermined direction, the first engaging claw 91 is lifted radially outward by the convex portion 75 of the concave-convex portion 76 to overcome the elastic force of the first claw force member 88. As a result, the first component 71 is allowed to rotate in the predetermined direction. On the other hand, when the first component 71 is to rotate relative to the second component 72 in the direction opposite to the predetermined direction, the engagement of the engaging concave portion 74 and the first engaging claw 91 prevents the first component 71 from rotating in the direction opposite to the predetermined direction. In short, the rotation transmission state switching device 8 acts as a ratchet-type one-way clutch.

[0142] The predetermined direction mentioned above coincides with the normal rotation direction of the input member 4. The normal rotation direction of the input member 4 refers to the rotation direction of the input member 4 when the vehicle moves forward.

[0143] The friction engagement device 7 has at least one first friction plate 30 and at least one second friction plate 31 capable of supporting axial relative displacement, and is arranged between any two elements among the above-mentioned sun element (sun gear 101), the above-mentioned ring element (ring gear 102), and the above-mentioned carrier element (carrier 103). By pushing the first friction plate 30 and the second friction plate 31 against each other, the connection mode is switched to the above-mentioned any two elements rotating as a whole, and by releasing the force pushing the first friction plate 30 and the second friction plate 31 against each other, the above-mentioned any two elements are switched to the relative rotation disconnection mode.

[0144] In this example, the friction engagement device 7 is provided between the sun gear 101 and the ring gear 102. In the above-mentioned connection mode, the sun gear 101 and the ring gear 102 rotate integrally, and in the above-mentioned disconnection mode, the sun gear 101 and the ring gear 102 rotate relatively. Thus, in the above-mentioned connection mode, torque is transmitted between the input member 4 and the rotating member 6, and in the above-mentioned disconnection mode, torque is not transmitted between the input member 4 and the rotating member 6.

[0145] In this example, the friction engagement device 7 includes a friction engagement portion 26 , an elastic urging member 27 , a cam device 28 , and an electric actuator 29 .

[0146] In this example, the friction engagement portion 26 is formed by a multi-plate clutch in which a plurality of first friction plates 30 supported by the rotating member 6 and a plurality of second friction plates 31 supported by the input member 4 are alternately overlapped.

[0147] The plurality of first friction plates 30 are supported on the outer peripheral surface of the first cylindrical portion 19 so as to be displaceable in the axial direction and non-rotatable relative to the first cylindrical portion 19 .

[0148] The plurality of second friction plates 31 are supported on the inner peripheral surface of the end portion on the other axial side of the input member 4 so as to be displaceable in the axial direction and non-rotatable relative to the input member 4 .

[0149] The elastic urging member 27 is provided between the rotating member 6 and the friction engagement portion 26 and elastically urges the first friction plate 30 and the second friction plate 31 in a direction of mutually pressing the first friction plate 30 and the second friction plate 31. In this example, the elastic urging member 27 includes a piston 32 and an elastic member 33.

[0150] The piston 32 is supported in a manner that does not allow axial displacement relative to the rotating member 6. In this example, the piston 32 is formed in a hollow circular plate shape, and is supported around a portion between the small-diameter flange portion 15 and the flange portion 16 in the rotating member 6 in a manner that allows axial displacement relative to the rotating member 6 in the axial direction. The piston 32 has an end surface on the other axial side of a radially outer portion facing an axially single side surface of the first friction plate 30 or the second friction plate 31, whichever is closest to the axially single side.

[0151] The elastic member 33 is provided between the rotating member 6 and the piston 32. In this example, the elastic member 33 is sandwiched in an elastically compressed state between the other axial side surface of the small-diameter flange portion 15 of the rotating member 6 and the one axial side surface of the piston 32. That is, the elastic urging member 27 uses the force of the elastic member 33 to elastically restore, and presses the first friction plate 30 or the second friction plate 31 closest to the one axial side toward the other axial side through the piston 32, and elastically urges the first friction plate 30 and the second friction plate 31 in a direction of pushing each other.

[0152] In this example, the elastic member 33 is composed of at least one (two in this example) disc spring. However, when implementing the present disclosure, the specific structure of the elastic member is not particularly limited. For example, the elastic member can also be composed of at least one coil spring.

[0153] The cam device 28 includes a driving cam 34 and a driven cam 35 supported so as to be relatively rotatable and relatively displaceable in the axial direction relative to the driving cam 34. As the driven cam 35 is relatively displaced in a direction in which the axial interval with the driving cam 34 is expanded in association with the rotation of the driving cam 34, the cam device 28 presses the elastic urging member 27 in a direction in which the force pressing the first friction plate 30 and the second friction plate 31 against each other is released.

[0154] In this example, the driving cam 34 is supported relative to the rotating member 6 in a manner that allows the driving cam 34 to rotate relative to the rotating member 6 and the input member 4 and does not allow the driving cam 34 to displace axially relative to the rotating member 6. Figure 4 As shown in FIGS. 1 and 1B , the drive cam 34 is supported by the cylindrical member 37 , the radial bearing 38 , and the angular contact ball bearing 39 so as to be relatively rotatable with respect to the rotating member 6 .

[0155] The tubular member 37 includes a cylindrical portion 40 and an outward flange portion 41 bent radially outward from the other axial end of the cylindrical portion 40. The tubular member 37 is supported and fixed to the fixing portion 10 by screwing or the like.

[0156] The radial bearing 38 includes an inner ring 42 externally fitted and fixed to the end portion on the other axial side of the rotating member 6; an outer ring 43 internally fitted and fixed to the cylindrical portion 40 of the tubular 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 example shown in the figure, the radial bearing 38 is composed of a multi-row deep groove ball bearing using balls as the rolling elements 44. However, the radial bearing is not particularly limited as long as it can support radial loads and axial loads, and can be composed of, for example, a deep groove ball bearing, a radial angular contact ball bearing, or a radial tapered roller bearing.

[0157] The angular contact ball bearing 39 includes an inner ring 45 fitted and fixed to the cylindrical portion 40 of the tubular member 37 , an outer ring 46 fitted and fixed to the drive cam 34 , and a plurality of balls 47 rotatably arranged between the inner ring 45 and the outer ring 46 .

[0158] In this example, the drive cam 34 has worm gear teeth 49 as helical gears on the outer peripheral surface, and has pin portions 50 protruding toward one side in the axial direction at multiple locations (three locations in the example shown) in the radial middle portion of one axial side surface in the circumferential direction.

[0159] The driven cam 35 is arranged around the rotating member 6 in a manner that allows only axial displacement. In this example, the driven cam 35 has a hollow circular plate shape and is supported in a manner that allows axial displacement relative to the fixed portion 10. In this example, the driven cam 35 is supported in a manner that allows axial displacement relative to the fixed portion 10 by spline engagement between the female spline portion 51 provided on the inner circumferential surface of the driven cam 35 and the male spline portion 52 provided on the outer circumferential surface of the axially one-side portion of the cylindrical portion 40 of the tubular member 37.

[0160] However, the method of supporting the driven cam relative to the fixed part is not particularly limited as long as the driven cam is supported so as to be able to move axially relative to the fixed part. For example, the driven cam may be supported so as to be able to move axially relative to the fixed part by engaging a convex portion provided on one of the driven cam and the fixed part with a concave groove key provided on the other.

[0161] like Fig.12As shown, the driven cam 35 has a rectangular hole 53 penetrating in the axial direction at multiple locations (three locations in the example shown) in the circumferential direction of the radial middle portion, and has substantially semicircular plate-shaped support plate portions 54a and 54b protruding toward the other axial side from each radial side portion of the rectangular hole 53. The radially outer support plate portion 54a of the support plate portions 54a and 54b has a support hole 55 penetrating in the radial direction as a circular hole, and the radially inner support plate portion 54b has a support recess 56 on the radially outer side surface, and the support recess 56 has a circular opening.

[0162] The driven cam 35 faces the piston 32 of the elastic urging member 27 via the thrust bearing 57 and the pressing member 58 .

[0163] The thrust bearing 57 is disposed between the pressing member 58 and the driven cam 35. The thrust bearing 57 includes a pair of raceway rings 59a and 59b and a plurality of rolling elements 60 that are freely disposed between the pair of raceway rings 59a and 59b. The raceway ring 59b on the other axial side of the pair of raceway rings 59a and 59b is supported and fixed to the driven cam 35.

[0164] The pressing member 58 has a cylindrical base 62 and a partial cylindrical portion 63 protruding toward one side in the axial direction from multiple locations (three locations in the example shown) in the circumferential direction of the end portion on one side in the axial direction of the base 62. The raceway 59a on one side in the axial direction of a pair of raceways 59a and 59b of the thrust bearing 57 is supported and fixed at the end portion on the other side in the axial direction of the base 62. The partial cylindrical portion 63 is inserted through the through hole 17 of the rotating member 6, and the front end portion (the end portion on one side in the axial direction) of the partial cylindrical portion 63 is opposed to the radial middle portion of the other side surface of the piston 32 in the axial direction.

[0165] In this example, a preload applying mechanism 61 for applying preload to the thrust bearing 57 is provided between the pressing member 58 and the rotating member 6. The preload applying mechanism 61 is sandwiched between the pressing member 58 and the other axial side surface of the first circular portion 18 constituting the flange portion 16 of the rotating member 6 in an elastically compressed state. Figure 2 As shown in FIG. 5( b ), even when the piston 32 is pressed axially to one side against the elastic restoring force of the elastic member 33 , the thrust bearing 57 is preloaded and is prevented from falling out from between the elastic urging member 27 and the cam device 28 .

[0166] The elastic force of the preload applying mechanism 61 is smaller than the elastic restoring force of the elastic member 33. The preload applying mechanism 61 is composed of, for example, at least one disc spring or at least one coil spring. In this example, the preload applying mechanism 61 is composed of one coil spring.

[0167] In this example, the cam device 28 includes a plurality of (three in this example) rolling elements 36 and a driving cam surface 48 provided on the driving cam 34 as a mechanism for relatively displacing the driving cam 34 and the driven cam 35 .

[0168] like Fig.11 As shown in FIG. 1 , the driving cam surface 48 is formed by alternately arranging the same number of concave portions and convex portions along the circumferential direction on the radially inner portion of the axially one side surface of the driving cam 34. Fig.14 (A)~ Fig.14 As shown in (D), the driving cam surface 48 is constructed by repeatedly arranging the rolling elements 36 a number of times (three times in this example) in the order of a first bottom 48a, a first inclined surface 48b, a first flat surface 48c, a second inclined surface 48d, a second bottom 48e, a third inclined surface 48f, a second flat surface 48g, and a fourth inclined surface 48h.

[0169] The first flat surface 48c and the second flat surface 48g of the driving cam surface 48 are located at the most one side in the axial direction, that is, at the front end of the convex portion, and the first bottom 48a and the second bottom 48e are located at the most other side in the axial direction. The third inclined surface 48f and the fourth inclined surface 48h have a larger inclination angle with respect to the virtual plane P orthogonal to the central axis of the driving cam 34 than the first inclined surface 48b with respect to the virtual plane P.

[0170] The inclination angles of the first inclined surface 48b, the third inclined surface 48f, and the fourth inclined surface 48h are all set to such a size that the rolling element 36 can move in both a rolling and climbing manner. The third inclined surface 48f and the fourth inclined surface 48h have opposite inclination directions and the same inclination angles.

[0171] However, the inclination angles of the third inclined surface 48f and the fourth inclined surface 48h may be different from each other. In addition, the inclination angle of the first inclined surface 48b and the inclination angles of the third inclined surface 48f and the fourth inclined surface 48h may be the same.

[0172] The inclination angle of the second inclined surface portion 48 d with respect to the virtual plane P can be set to any value as long as the rolling element 36 can climb.

[0173] The rolling elements 36 each have a cylindrical shape and are rotatably supported relative to the support plates 54a and 54b via a cylindrical support shaft 64 and a plurality of rollers 65. That is, the end portion of the support shaft 64 on the radially outer side with the central axis of the driven cam 35 as the center is embedded and fixed in the support hole 55 of the radially outer support plate 54a, and the end portion of the support shaft 64 on the radially inner side with the central axis of the driven cam 35 as the center is embedded and fixed in the support recess 56 of the radially inner support plate 54b.

[0174] The plurality of rollers 65 are rotatably sandwiched between the inner circumference of the rolling element 36 and the outer circumference of the axial middle portion of the support shaft 64. Thus, the rolling element 36 is supported by the driven cam 35 and freely rotates (rotates) around the rotation axis C in radial directions around the central axis of the driven cam 35.

[0175] When the rolling element 36 is supported by the driven cam 35, one axial side portion of the rolling element 36 is disposed inside the rectangular hole 53. The outer peripheral surface of each rolling element 36 rolls against a driving cam surface 48 provided on the other axial side surface of the driving cam 34.

[0176] In the two-stage transmission 1 of this example, the driving cam 34 is driven to rotate, so that the climbing amount of the rolling element 36 from the first bottom 48a or the second bottom 48e in the driving cam surface 48 is increased or decreased, thereby causing the driven cam 35 to move axially and switch the connection state and disconnection state of the friction engagement part 26.

[0177] When the friction engagement portion 26 is set to the cut-off state, as shown in FIG. Fig.14 (B) and Fig.14 As shown in (D), the rolling element 36 is positioned on the first flat surface 48c or the second flat surface 48g of the driving cam surface 48, or the amount of climbing toward the first inclined surface 48b, the second inclined surface 48d, the third inclined surface 48f, or the fourth inclined surface 48h is increased.

[0178] By moving the driven cam 35 in the direction of increasing the axial interval with the driving cam 34, i.e., in the axial direction, the piston 32 of the elastic force member 27 is pressed in the axial direction through the thrust bearing 57 and the pressing member 58, thereby elastically compressing the elastic member 33. As a result, the force that presses the first friction plate 30 and the second friction plate 31 against each other is reduced and eventually lost. In this way, the friction engagement portion 26 is cut off, and the friction engagement device 7 is switched to the cut-off mode.

[0179] On the other hand, when the friction engagement portion 26 is set to the connected state, as shown in FIG. Fig.14 (A) and Fig.14As shown in (C), the rolling element 36 is positioned at the first bottom portion 48a or the second bottom portion 48e of the driving cam surface 48, or the amount of climbing toward the first inclined surface portion 48b, the second inclined surface portion 48d, the third inclined surface portion 48f, or the fourth inclined surface portion 48h is reduced.

[0180] Thus, the driven cam 35 moves in the direction of reducing the axial interval with the driving cam 34, that is, in the other axial side, thereby reducing the force of the piston 32 pressing the elastic force member 27 in the axial direction. If the force pressing the piston 32 in the axial direction is reduced, the piston 32, the thrust bearing 57 and the pressing member 58 are pressed in the axial direction in the other axial direction mainly by the elastic restoring force of the first friction plate 30 and the elastic member 33, and the first friction plate 30 or the second friction plate 31 closest to the axial direction is pressed in the axial direction in the other axial direction by the piston 32. Therefore, the friction engagement portion 26 is connected by the mutual pressing of the first friction plate 30 and the second friction plate 31, and the friction engagement device 7 is switched to the connection mode.

[0181] In the two-stage transmission 1 of this example, the driven cam 35 can be reliably displaced in the axial direction by rotating the driving cam 34 , and the mode switching of the two-stage transmission 1 can be performed with high accuracy.

[0182] When balls are used as rolling elements, when the driving cam is rotated, sliding may occur at the rolling contact portion between the surface of the rolling element and the driving cam surface. When sliding occurs at the rolling contact portion between the surface of the rolling element and the driving cam surface, the driven cam may not be displaced in the axial direction, or the axial displacement amount of the driven cam relative to the rotation amount of the driving cam may not be sufficiently ensured.

[0183] In the two-stage transmission 1 of this example, rollers are used as rolling elements 36, and the rolling elements 36 are supported so as to freely rotate (rotate) about the rotation axis C in a radial direction about the central axis of the driven cam 35 relative to the driven cam 35. Therefore, it is possible to prevent sliding from occurring at the rolling contact portion between the outer peripheral surface of the rolling element 36 and the driving cam surface 48, and the driven cam 35 can be reliably displaced in the axial direction based on the rotation of the driving cam 34. As a result, the mode switching of the two-stage transmission 1 can be performed with high precision. However, balls can also be used as rolling elements constituting the cam device.

[0184] In this example, the cam device 28 is constructed by clamping a rolling body 36 between a driving cam 34 and a driven cam 35. However, in the implementation of the present disclosure, the cam device is not particularly limited as long as it can press the elastic force-applying component in the direction of releasing the force that pushes the first friction plate and the second friction plate against each other, and any other known mechanism can be used.

[0185] For example, as a cam device, there can be adopted: a structure in which a rolling body is arranged between the driving cam surface of the driving cam and the driven cam surface of the driven cam; a structure in which the driving cam surface of the driving cam and the driven cam surface of the driven cam are directly engaged (slid) with each other; or a structure having a driven cam and a driving cam, wherein the driven cam has a guide groove extending in the circumferential direction and changing in the axial direction on the outer peripheral surface, and the driving cam has an engaging protrusion that engages in a manner capable of displacement along the above-mentioned guide groove.

[0186] The electric actuator 29 includes a shift motor 66 and a speed reducer 67 , and the drive cam 34 is rotationally driven by the shift motor 66 via the speed reducer 67 .

[0187] In this example, the speed reducer 67 is composed of a worm speed reducer. That is, the speed reducer 67 is composed of a worm gear provided on the outer peripheral surface of a worm 68 connected to the output shaft of the shift motor 66, and a worm gear 49 provided on the outer peripheral surface of the drive cam 34. The worm 68 is supported by a pair of support bearings 69a and 69b so as to be rotatable relative to the fixed portion 10.

[0188] However, the speed reducer 67 may 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 providing a belt or chain between the output shaft of the electric motor and the drive cam.

[0189] In this example, a return spring 70 is further provided between the first friction plate 30 and the second friction plate 31, and the return spring 70 elastically applies force in a direction of increasing the distance between the first friction plate 30 and the second friction plate 31. The elastic force of the return spring 70 is smaller than the elastic restoring force of the elastic member 33 of the elastic urging member 27. When the friction engagement portion 26 is set to the cut-off state, the distance between the first friction plate 30 and the second friction plate 31 is increased by the action of the return spring 70, and the friction engagement portion 26 can be reliably cut off.

[0190] The two-stage transmission 1 of this example has a first mode in which the rotation transmission state switching device 8 is set to the free mode and the friction engagement device 7 is set to the connected mode, and a second mode in which the rotation transmission state switching device 8 is set to the locked mode and the friction engagement device 7 is set to the disconnected mode.

[0191] Specifically, by setting the rotation transmission state switching device 8 to the free mode and the friction engagement device 7 to the connection mode, when the two-stage transmission 1 is switched to the first mode, the planetary speed change mechanism 9 is in a glued state where the entirety rotates integrally. In this state, the torque input to the input member 4 is not increased but is transmitted to the output member 5 as it is.

[0192] In contrast, by setting the rotation transmission state switching device 8 to the lock mode and the friction engagement device 7 to the disconnection mode, the two-stage transmission 1 is switched to the second mode, and the torque input and output to the input member 4 is increased by the planetary speed change mechanism 9 and then transmitted to the output member 5. That is, in the two-stage transmission 1 of this example, the first mode corresponds to a low reduction ratio mode in which the reduction ratio between the input member 4 and the output member 5 is small, and the second mode corresponds to a high reduction ratio mode in which the reduction ratio is larger than that in the low reduction ratio mode.

[0193] The two-stage transmission 1 of this example passes through the speed reduction ratio switching mode during the switching from the high speed reduction ratio mode (second mode) to the low speed reduction ratio mode (first mode). In addition, the two-stage transmission 1 of this example can also be switched to a neutral mode in which no torque is transmitted between the input member 4 and the output member 5, and a parking mode in which the rotation of the output member 5 is locked.

[0194] <Low reduction ratio mode (first mode)>

[0195] When the two-stage transmission 1 is switched to the low speed reduction ratio mode, the friction engagement device 7 is switched to the connection mode, and the rotation transmission state switching device 8 is switched to the free mode.

[0196] In this example, the driving cam 34 is rotated by the electric actuator 29, so that the rolling element 36 is located at the first bottom portion 48a of the driving cam surface 48, and the driven cam 35 is displaced in a direction (the other axial side) in which the axial distance from the driving cam 34 is reduced. As a result, the force of the piston 32 pressing the elastic urging member 27 in one axial direction is lost.

[0197] The piston 32, the thrust bearing 57 and the pressing component 58 are pressed toward the other axial side mainly by the elastic restoring force of the first friction plate 30 and the elastic component 33, and the first friction plate 30 or the second friction plate 31 closest to one axial side is pressed toward the other axial side by the piston 32.

[0198] As a result, the first friction plates 30 and the second friction plates 31 are pressed against each other, the friction engagement portion 26 is connected, and the friction engagement device 7 is switched to the connection mode. As a result, the input member 4 rotates integrally with the rotating member 6, and the sun gear 101 and the ring gear 102 rotate integrally.

[0199] When the friction engagement device 7 is switched to the connection mode, the phase of the circumferential direction of the component 73 relative to the second component 72 is adjusted based on the mode selection, such as Fig.19 As shown in (A), the first engagement claw 91 is lifted radially outward by the protrusion 97, and the second engagement claw 94 is lifted radially outward.

[0200] As a result, the engagement between the engagement recess 74 of the first member 71 and the first engagement claw 91 and the second engagement claw 94 is disengaged, and the rotation transmission state switching device 8 is switched to a free mode that allows the first member 71 to rotate relative to the second member 72 regardless of the relative rotation direction of the first member 71 and the second member 72. As a result, the rotation of the rotating member 6 relative to the fixed portion 10 is allowed, and the rotation of the sun gear 101 is allowed.

[0201] In the low reduction ratio mode, the sun gear 101, the ring gear 102 and the carrier 103 rotate in the same direction and at the same speed, and the planetary speed change mechanism 9 is in a glued state that rotates as a whole. Figure 2 As indicated by the bold line in (a), the rotational torque of the input member 4 is transmitted to the input member 4 , the carrier 103 , and the output member 5 in this order, and is taken out from the output member 5 .

[0202] <High reduction ratio mode (second mode)>

[0203] When the two-stage transmission 1 is switched to the high reduction ratio mode, the friction engagement device 7 is switched to the disconnection mode, and the rotation transmission state switching device 8 is switched to the lock mode.

[0204] In this example, the driving cam 34 is rotated by the electric actuator 29, so that the rolling element 36 is located on the first flat surface 48c of the driving cam surface 48, and the driven cam 35 is displaced in a direction (one axial side) in which the axial interval with the driving cam 34 is increased. Thus, the piston 32 of the elastic urging member 27 is pressed in one axial direction via the thrust bearing 57 and the pressing member 58, thereby elastically compressing the elastic member 33, and the force pressing the first friction plate 30 and the second friction plate 31 against each other is lost.

[0205] The return spring 70 increases the distance between the first friction plate 30 and the second friction plate 31, disconnecting the friction engagement portion 26, thereby switching the friction engagement device 7 to the disconnection mode. As a result, the input member 4 and the rotating member 6 rotate relative to each other, and the sun gear 101 and the ring gear 102 can rotate relative to each other.

[0206] When the friction engagement device 7 is switched to the cut-off mode, the phase of the mode selection component 73 relative to the second component 72 in the circumferential direction is adjusted, as shown in FIG. Fig.19 As shown in (B), the protrusion 97 is located at a portion offset from the first engagement claw 91 and the second engagement claw 94 in the circumferential direction.

[0207] As a result, the engagement recess 74 of the first member 71 engages with the first engagement claw 91 and the second engagement claw 94, and the rotation transmission state switching device 8 switches to a locking mode that blocks the rotation of the first member 71 relative to the second member 72 regardless of the relative rotation direction of the first member 71 and the second member 72. As a result, the rotation of the rotating member 6 relative to the fixed portion 10 is blocked, and the rotation of the sun gear 101 is blocked.

[0208] In high reduction ratio mode, such as Figure 2 As shown by the bold line in (b), the rotation torque of the input member 4 is transmitted in the order of the input member 4, the ring gear 102, the rotational motion of the planetary gear 104, the revolution motion of the planetary gear 104 based on the meshing with the sun gear 101, the carrier 103, and the output member 5, and is taken out from 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 102 and the sun gear 101 (the number of teeth of the ring gear 102 / the number of teeth of the sun gear 101).

[0209] In the two-stage transmission 1 of this example, the reduction ratio between the input member 4 and the output member 5 can be switched to two stages, high and low, by switching the mode of the friction engagement device 7 and the mode of the rotation transmission state switching device 8 based on the rotational driving of a drive cam 34 by an electric actuator 29.

[0210] Specifically, for example, in the region where the power input to the input member 4 is low speed and high torque, the two-stage transmission 1 is switched to a high reduction ratio mode, and in the region where the power is high speed and low torque, it is switched to a low reduction ratio mode. Therefore, the acceleration performance and high speed performance of electric vehicles and hybrid vehicles when they are driven only by electric motors are used. Fig.41 The continuous characteristics of the solid line a to the left of point P and the dashed line b to the right of point P can be approximated Fig.41 The gasoline engine vehicle is shown by the dashed line c.

[0211] In the two-stage transmission 1 of this example, the mode of the friction engagement device 7 and the mode of the rotation transmission state switching device 8 are switched based on the rotational drive of a driving cam 34 by the electric actuator 29. That is, in the two-stage transmission 1 of this example, a hydraulic system for controlling the friction engagement device such as the clutch and the brake is not required. Therefore, in electric vehicles and hybrid vehicles, the system can be simplified to reduce costs, and the power consumption performance can be improved.

[0212] Furthermore, when the two-stage transmission of the present disclosure is implemented, the mode switching of the friction engagement device and the mode switching of the rotation transmission state switching device can also be performed using different actuators.

[0213] In this example, in order to prevent the occurrence of a speed change shock associated with the switching from the high reduction ratio mode to the low reduction ratio mode, the output torque and the rotation number Rs of the drive motor 2 and the rotation number of the shift motor 66 are controlled, and the two-stage transmission 1 is switched to the reduction ratio switching mode. Thus, it is configured to prevent the rotation torque of the output member 5 from changing discontinuously and switch from the high reduction ratio mode to the low reduction ratio mode.

[0214] <Reduction ratio switching mode>

[0215] When the high speed reduction ratio mode of the two-stage transmission 1 is switched to the low speed reduction ratio mode, the phase of the mode selection member 73 relative to the second member 72 in the circumferential direction is adjusted, as shown in FIG. Fig.19 As shown in FIG. 5C , only the second engagement claw 94 is lifted radially outward by the protruding portion 97 against the elastic force of the second claw urging member 89 .

[0216] Thus, only the first engagement claw 91 is engaged with the engagement recess 74 of the first member 71, and the rotation transmission state switching device 8 allows the first member 71 to rotate relative to the second member 72 in the predetermined direction ( Fig.19 (C)) and switches to a one-way clutch mode that prevents rotation in the direction opposite to the predetermined direction.

[0217] At the same time as the rotation transmission state switching device 8 is switched to the one-way clutch mode, or after it is switched to the one-way clutch mode, the friction engagement device 7 starts to switch from the disconnection mode to the connection mode. Fig.14 (B) The state shown is Fig.14 In the state shown in (A), the driver descends along the first inclined surface portion 48 b of the driving cam surface 48 .

[0218] As the amount of the rolling element 36 climbing from the first bottom portion 48a of the driving cam surface 48 gradually decreases, the force of the first friction plate 30 and the second friction plate 31 pressing each other gradually increases (the coupling force F of the friction engagement portion 26 gradually increases). At this time, the input member 4 rotates while sliding (sliding contact) the axial side surfaces of the second friction plate 31 along the axial side surfaces of the first friction plate 30.

[0219] During the rotation of the input member 4 in the forward direction, if the coupling force F of the friction engagement portion 26 gradually increases, the torque applied to the second member 72 of the rotation transmission state switching device 8 in the direction opposite to the above-mentioned predetermined direction gradually decreases. At this time, the rotation transmission state switching device 8 switches to the one-way clutch mode, and the second member 72 does not rotate even if the torque is applied to the second member 72 in the direction opposite to the above-mentioned predetermined direction. After the torque applied to the second member 72 in the direction opposite to the above-mentioned predetermined direction gradually decreases to 0, if the direction of the torque applied to the second member 72 is reversed (torque in the above-mentioned predetermined direction is applied to the second member 72), the second member 72 is allowed to rotate in the above-mentioned predetermined direction at that moment.

[0220] <Neutral Mode>

[0221] When the two-stage transmission 1 is switched to the neutral mode, the friction engagement device 7 is switched to the disconnection mode, and the rotation transmission state switching device 8 is switched to the free mode.

[0222] The electric actuator 29 rotates the driving cam 34, and the rolling element 36 is positioned on the second flat surface 48g of the driving cam surface 48, so that the driven cam 35 is displaced in a direction (one axial side) in which the axial interval with the driving cam 34 is increased. Thus, the piston 32 of the elastic urging member 27 is pressed in one axial direction via the thrust bearing 57 and the pressing member 58, thereby elastically compressing the elastic member 33, and the force pressing the first friction plate 30 and the second friction plate 31 against each other is lost.

[0223] The return spring 70 increases the distance between the first friction plate 30 and the second friction plate 31, disconnects the friction engagement portion 26, and switches the friction engagement device 7 to the disconnection mode. As a result, the input member 4 and the rotating member 6 rotate relative to each other, and the sun gear 101 and the ring gear 102 can rotate relative to each other.

[0224] When the friction engagement device 7 is switched to the connection mode, the phase of the circumferential direction of the component 73 relative to the second component 72 is adjusted based on the mode selection, such as Fig.19 As shown in (A), the first engagement claw 91 is lifted radially outward by the protrusion 97, and the second engagement claw 94 is lifted radially outward.

[0225] As a result, the engagement between the engagement recess 74 of the first member 71 and the first engagement claw 91 and the second engagement claw 94 is disengaged, and the rotation transmission state switching device 8 is switched to a free mode that allows the first member 71 to rotate relative to the second member 72 regardless of the relative rotation direction of the first member 71 and the second member 72. As a result, the rotation of the rotating member 6 relative to the fixed portion 10 is allowed, and the rotation of the sun gear 101 is allowed.

[0226] In the neutral mode, the input member 4 and the output member 5 idle relative to each other, and no torque is transmitted between the input member 4 and the output member 5 .

[0227] <Parking lock mode>

[0228] When the two-stage transmission 1 is switched to the parking lock mode, the friction engagement device 7 is switched to the connection mode, and the rotation transmission state switching device 8 is switched to the lock mode.

[0229] The electric actuator 29 rotates the driving cam 34, so that the rolling element 36 is located at the second bottom 48e of the driving cam surface 48, and the driven cam 35 is displaced in the direction (the other axial side) in which the axial interval with the driving cam 34 is reduced. As a result, the force of the piston 32 pressing the elastic force applying member 27 toward one axial side is lost. And, mainly by the elastic restoring force of the first friction plate 30 and the elastic member 33, the piston 32, the thrust bearing 57 and the pressing member 58 are pressed toward the other axial side, and the first friction plate 30 or the second friction plate 31 closest to one axial side is pressed toward the other axial side by the piston 32.

[0230] Thus, the first friction plate 30 and the second friction plate 31 are pressed against each other, the friction engagement portion 26 is connected, and the friction engagement device 7 is switched to the connection mode. As a result, the input member 4 is prevented from rotating relative to the rotating member 6, and the ring gear 102 is prevented from rotating relative to the sun gear 101.

[0231] When the friction engagement device 7 is switched to the connection mode, the phase of the circumferential direction of the component 73 relative to the second component 72 is adjusted based on the mode selection, such as Fig.19 As shown in (B), the protrusion 97 is located at a portion offset from the first engagement claw 91 and the second engagement claw 94 in the circumferential direction.

[0232] As a result, the engagement recess 74 of the first member 71 engages with the first engagement claw 91 and the second engagement claw 94, and the rotation transmission state switching device 8 switches to a locking mode that blocks the rotation of the first member 71 relative to the second member 72 regardless of the relative rotation direction of the first member 71 and the second member 72. As a result, the rotation of the rotating member 6 relative to the fixed portion 10 is blocked, and the rotation of the sun gear 101 is blocked.

[0233] In the parking lock mode, the rotation of the input member 4 and the output member 5 is locked.

[0234] use Fig.25 as well as Fig.26The control of the drive motor 2 and the shift motor 66 to prevent the rotation torque of the output member 5 from changing discontinuously (suddenly) and thus preventing the occurrence of a speed change shock when switching from the high reduction ratio mode to the low reduction ratio mode is described. Hereinafter, an example of maintaining the rotation torque of the output member 5 substantially constant before and after switching from the high reduction ratio mode to the low reduction ratio mode is described.

[0235] Based on the vehicle's running speed, accelerator opening, and other conditions, when the high reduction ratio mode is switched to the low reduction ratio mode, the electric actuator 29 firstly drives the drive cam 34 to rotate, thereby switching the rotation transmission state switching device 8 to the one-way clutch mode, and the phase of the drive cam 34 in the rotation direction is moved to the clutch touch point θ. f (S1).

[0236] Clutch touch point θ f The point at which the elastic urging member 27 starts to generate a force that pushes the first friction plate 30 and the second friction plate 31 against each other. In other words, the clutch touch point θ f The clutch clearance C is the point where the end of the piston 32 on the other axial side starts to contact the first friction plate 30 or the second friction plate 31 located on the most axial side. f (Refer to Fig.24 ) becomes 0. In this example, the clutch touch point θ f It is obtained in advance by the function described later.

[0237] If the phase of the driving cam 34 in the rotation direction moves to the clutch contact point θ f , then it shifts to the torque stage (S2). In the torque stage, the electric actuator 29 rotates the drive cam 34 at a predetermined rotation number (rotation speed), so that the climbing amount of the rolling element 36 from the first bottom 48a is reduced, thereby gradually increasing the pressing force between the first friction plate 30 and the second friction plate 31, that is, the connecting force F of the friction engagement portion 26. At the same time, the output torque of the drive motor 2 is gradually increased.

[0238] That is, assuming that the output torque of the drive motor 2 is maintained constant, in the torque stage, the torque transmitted to the friction engagement portion 26 increases with the increase of the connection force F of the friction engagement portion 26, so that the rotation torque of the output member 5 decreases. In the two-stage transmission 1 of this example, regardless of the increase of the connection force F of the friction engagement portion 26, the output torque of the drive motor 2 is gradually increased according to the increase of the connection force F of the friction engagement portion 26, that is, the rotation amount of the drive cam 34, in such a manner that the rotation torque of the output member 5 can be maintained substantially constant.

[0239] The relationship between the rotation amount of the driving cam 34 and the increase in the output torque of the driving motor 2 is obtained by preliminary experiments and calculations. In this example, the rotation number of the driving cam 34 in S2 is made smaller than the rotation number of the driving cam 34 in S1. However, the rotation number of the driving cam 34 in S2 can be the same as the rotation number of the driving cam 34 in S1, or can be greater than the rotation number of the driving cam 34 in S1.

[0240] More specifically, in S2, the drive cam 34 is rotated by a predetermined angle, and the output torque of the drive motor 2 is increased by an amount corresponding to the rotation amount of the drive cam 34. In the next S3, it is determined whether the torque phase is completed.

[0241] In the torque phase, as the coupling force F of the friction engagement portion 26 increases, the torque transmitted to the friction engagement portion 26 (through the friction engagement portion 26), i.e., the clutch torque, increases, and the torque applied to the second component 72 of the rotation transmission state switching device 8 in the direction opposite to the above-mentioned predetermined direction gradually decreases. After the torque applied to the second component 72 in the direction opposite to the above-mentioned predetermined direction gradually decreases and becomes 0, if the direction of the torque applied to the second component 72 is reversed (the torque in the above-mentioned predetermined direction is applied to the second component 72), the second component 72 is allowed to rotate in the above-mentioned predetermined direction at that moment, and the rotation of the sun gear 101 is allowed. If the sun gear 101 rotates, the number of rotations Rs of the output shaft 11 of the drive motor 2 begins to decrease.

[0242] In the two-stage transmission 1 of this example, when it is determined that the number of revolutions Rs of the output shaft 11 decreases by more than a predetermined value based on the output signal of the rotation sensor mounted on the output shaft 11 of the drive motor 2, it is determined that the torque phase ends. This determination is made based on the rotation sensor mounted on the output shaft 11 of the drive motor 2.

[0243] If it is determined that the rotation speed Rs of the output shaft 11 is substantially constant, that is, the decrease in the rotation speed Rs of the output shaft 11 is smaller than the predetermined value and the torque phase has not ended, the process returns to S2 .

[0244] In S3, when it is determined that the decrease in the rotation number Rs of the output shaft 11 is equal to or greater than the predetermined value and the torque phase is ended, the process shifts to the inertia phase (S4-1 to S4-3).

[0245] In the inertia stage, first, the output torque of the drive motor 2 is rapidly reduced to promote a further reduction in the number of rotations Rs of the output shaft 11 (S4-1). The reduction in the output torque of the drive motor 2 is not particularly limited as long as it can promote a further reduction in the number of rotations Rs of the output shaft 11. Specifically, for example, the output torque of the drive motor 2 can be reduced to 0 or to a negative value.

[0246] After the rotation number Rs of the output shaft 11 starts to decrease, the output torque of the drive motor 2 is increased so that the rotation torque of the input member 4 becomes the rotation torque that the output member 5 should output when the two-stage transmission 1 is switched to the low reduction ratio mode, that is, the target torque (S4-2). In this example, the rotation torque of the output member 5 is kept substantially constant before and after the switch from the high reduction ratio mode to the low reduction ratio mode, so the output torque of the drive motor 2 is increased until the rotation torque of the input member 4 is equal to the rotation torque of the output member 5 at the start of the switch from the high reduction ratio mode to the low reduction ratio mode.

[0247] The speed control for increasing the output torque of the drive motor 2 is to increase the rotational torque of the input member 4 to the target torque before the inertia phase is completed. In this example, the output torque of the drive motor 2 is controlled based on the friction coefficient μ between the first friction plate 30 and the second friction plate 31 and the difference (rotation difference) V between the input rotation number Rin and the output rotation number Rout of the friction engagement part 26. The input rotation number Rin of the friction engagement part 26 is the rotation number of the first friction plate 30, which is the same as the rotation number of the ring gear 102 and the rotation number of the input member 4 in this example. In addition, the output rotation number Rout of the friction engagement part 26 is the rotation number of the second friction plate 31, which is the same as the rotation number of the sun gear 101 in this example.

[0248] In the two-stage transmission 1 of this example, as the rotation number Rs of the output shaft 11 decreases, the rotation number of the input member 4 decreases, and as the rotation difference V decreases, the output torque of the drive motor 2 increases. When the rotation difference V becomes 0, the rotation torque of the input member 4 is controlled to become the target torque. The relationship between the friction coefficient μ and the rotation difference V, that is, the μ-V characteristic, is obtained in advance by the function described later.

[0249] Next, in S4-3, it is determined whether the rotation difference V is 0. In the two-stage transmission 1 of this example, if the rotation difference V becomes 0, the input rotation number Rin and the output rotation number Rout of the friction engagement part 26 are equal, and the planetary speed change mechanism 9 becomes glued, and the rotation number of the input member 4 and the rotation number of the output member 5 become equal.

[0250] In this example, it is determined whether the rotation difference V is 0 by determining whether the rotation speed of the input member 4 is equal to the rotation speed of the output member 5. Specifically, it is determined whether the difference ΔR between the rotation speed of the input member 4 and the rotation speed of the output member 5 is within a predetermined range. This determination is performed based on the output signal of the rotation sensor installed on the output shaft 11 or the input member 4 and the output member 5, respectively.

[0251] If it is determined that the difference ΔR is not within the predetermined range, that is, if it is determined that the rotation difference V is not 0, S4 - 3 is executed again after a predetermined time has passed.

[0252] When it is determined that the difference ΔR is within the predetermined range, that is, when the rotation difference V is 0, it is determined that the inertia phase is completed, and the process proceeds to the next S5 .

[0253] In S5, the driving cam 34 is rotated to a predetermined phase in the circumferential direction by the electric actuator 29, so that the rolling element 36 is located at the first bottom 48a of the driving cam surface 48, and the driven cam 35 is displaced toward the direction of reducing the axial interval with the driving cam 34, that is, toward the other axial side. Thus, the piston gap Cp is ensured between the end of one axial side of the pressing member 58 and the other axial side surface of the piston 32. In other words, the piston gap Cp is set to be equal to or greater than 0, preferably greater than 0.

[0254] After the rolling element 36 is moved to the first bottom 48a, the process ends. According to the above description, the two-stage transmission 1 is switched from the high reduction ratio mode to the low reduction ratio mode. Then, by maintaining the phase of the driving cam 34 in the circumferential direction, the two-stage transmission 1 is maintained in the low reduction ratio mode.

[0255] In the two-stage transmission 1 of this example, by controlling the drive motor 2 and the shift motor 66, even when switching between the high reduction ratio mode and the low reduction ratio mode, the rotation torque of the output member 5 can be prevented from changing (suddenly) and the generation of a speed change shock can be prevented. However, in order to prevent the generation of a speed change shock, it is important to control the output torque and the number of revolutions Rs of the drive motor 2 and the timing of the rotation of the shift motor 66.

[0256] For example, although the phase in the rotation direction of the driving cam 34 has not reached the clutch contact point θ f , but if it is transferred to S2, the output torque of the drive motor 2 is increased, then Fig.26 As shown by the dotted line in (F), there is a possibility that the rotation torque of the output member 5 increases unexpectedly.

[0257] As the two-stage transmission 1 is used, if the wear of the first friction plate 30 and the second friction plate 31 increases, the amount of pressure required by the elastic force component 27 to switch the friction engagement device 7 to the connection mode toward the first friction plate 30 or the second friction plate 31 on the axially closest side increases.

[0258] In other words, the amount of pressure required to be applied to one side of the piston 32 by the cam device 28 when the friction engagement device 7 is switched to the cut-off mode is reduced. 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 is changed from Fig.21 The state shown in (a) Fig.21 That is, if the wear amount of the first friction plate 30 and the second friction plate 31 increases, the clutch touch point θf Become smaller.

[0259] Fig.21 (a) and Fig.21 (b) is a graph showing the relationship between the rotation angle θ of the drive cam 34 and the output torque T and the current value A of the shift motor 66 when the friction engagement device 7 is switched from the connection mode to the disconnection mode. Fig.21 (a) shows the first friction plate 30 and the second friction plate 31 when they are new and unworn. Fig.21 (b) shows a case where the wear of the first friction plate 30 and the second friction plate 31 has progressed significantly.

[0260] If the wear amount of the first friction plate 30 and the second friction plate 31 increases, the piston contact point θp also becomes smaller. The piston contact point θp is the point where the elastic force applying member 27 begins to be pressed in the direction of releasing the force that pushes the first friction plate 30 and the second friction plate 31 against each other when the drive cam 34 is rotated in the direction of switching the friction engagement portion 26 from the connected state to the disconnected state. In other words, the piston contact point θp is the point where the piston gap Cp (refer to FIG. 1 ) between the axial end of the pressing member 58 on one side and the other axial side of the piston 32 begins to be generated when the drive cam 34 is rotated in the direction of switching the friction engagement portion 26 from the disconnected state to the connected state. Fig. 22 ) point.

[0261] The two-stage transmission 1 of this example has a function for preventing speed change shock regardless of the wear of the first friction plate 30 and the second friction plate 31. Specifically, the two-stage transmission 1 of this example has: a first function for detecting the piston touch point θp; a first function for detecting the clutch touch point θp; f and when switching between high reduction ratio mode and low reduction ratio mode, based on the piston touch point θp and / or the clutch touch point θ f The third function is to adjust the rotation amount of the drive cam 34 .

[0262] from Fig.21 (a) and Fig.21 (b) It is also clear that when the mode of the friction engagement device 7 is switched, the output torque T of the shift motor 66 and the current value A of the shift motor 66 change in the same tendency. The two-stage transmission 1 of this example detects the piston touch point θp and the clutch touch point θp based on the current value A of the shift motor 66 when the friction engagement device 7 is switched from the connection mode to the disconnection mode. f .

[0263] When the friction engagement device 7 is switched to the connection mode, the rolling element 36 of the cam device 28 is located at the first bottom 48a of the driving cam surface 48. Fig. 22As shown, there is a piston gap Cp between the end of the pressing member 58 on one axial side and the other axial side of the piston 32. Based on the existence of the piston gap Cp, the displacement of the piston 32 to the other axial side is allowed. Therefore, the piston 32 is elastically pressed to the other axial side by the force of the elastic member 33 to elastically restore, and the first friction plate 30 or the second friction plate 31 closest to the one axial side is pressed toward the other axial side by the piston 32, thereby the first friction plate 30 and the second friction plate 31 are pushed against each other.

[0264] When the friction engagement device 7 is switched from the connection mode to the disconnection mode, the drive cam 34 is rotated in the predetermined direction by energizing the shift motor 66, so that the amount of the rolling element 36 climbing from the first bottom 48a increases. At this time, the current value A of the shift motor 66 is substantially constant ( Fig.21 (a) and Fig.21 (b) range α).

[0265] As the amount of the rolling element 36 climbing up from the first bottom portion 48a increases, if the pressing member 58 is moved axially to one side, Fig.23 As shown, the end portion on one axial side of the pressing member 58 is in contact with the other axial side surface of the piston 32. In other words, the piston clearance Cp becomes zero.

[0266] If from Fig.23 In the state shown, the driving cam 34 is further driven to rotate in the predetermined direction by the shift motor 66, and the piston 32 is pressed toward one side in the axial direction through the driven cam 35 via the pressing member 58 against the elastic restoring force of the elastic member 33. 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 57, and the remaining part is supported by the fixed portion 10 via the friction engagement portion 26 and the rotation transmission state switching device 8.

[0267] When the piston 32 is pressed toward one side in the axial direction, the force pressing the first friction plate 30 and the second friction plate 31 against each other gradually decreases mainly due to the elastic restoring force of the second friction plate 31 and the elastic member 33. That is, the fastening force F of the friction engagement portion 26 gradually decreases.

[0268] While the coupling force F of the friction engagement portion 26 is gradually reduced, the current value A of the shift motor 66 is increased at a substantially constant rate of increase (gradient) ( Fig.21 (a) and Fig.21 That is, the increase rate of the current value A in the range β is greater than the increase rate of the current value A in the range α.

[0269] In the two-stage transmission 1 of this example, according to the first function, in order to switch the friction engagement device 7 from the connection mode to the disconnection mode, after the shift motor 66 starts to be energized, 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 in the rotation direction of the drive cam 34 when the current value A of the shift motor 66 starts to increase at an increase rate greater than a predetermined first threshold value is detected as the piston contact point θp where the piston clearance Cp becomes 0. The first threshold value can be obtained by preliminary experiments, simulations, etc.

[0270] The increase rate of the current value A is the increase amount ΔA of the current value A per unit rotation angle Δθ of the drive cam 34. When the drive cam 34 is rotated in the predetermined direction at a constant rotation speed, the increase amount ΔA of the current value A per unit time can also be used for determination.

[0271] If the connection force F of the friction engagement portion 26 gradually decreases and becomes 0, then from this moment on, Fig.24 As shown in FIG. 1 , a clutch clearance C is generated between the end of the piston 32 on the other axial side and the first friction plate 30 or the second friction plate 31 located on the most axial side. f If clutch clearance C begins to occur f , substantially 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 .

[0272] In this way, the clutch clearance C begins to be generated. f After that, the current value A of the shift motor 66 increases slowly and logarithmically ( Fig.21 (a) and Fig.21 That is, the increase rate of the current value A in the range γ is smaller than the increase rate of the current value A in the range β.

[0273] In the two-stage transmission 1 of this example, according to the second function, when the friction engagement device 7 is switched from the connection mode to the disconnection mode, after the phase in the rotation direction of the drive cam 34 exceeds the piston contact point θp, the phase θ in the rotation direction of the drive cam 34 when the increase rate of the current value A of the shift motor 66 becomes less than a predetermined second threshold value is used as the clutch clearance C. f The clutch touch point θ becomes 0 f The second threshold is smaller than the first threshold. The second threshold can be obtained by preliminary experiments, simulations, etc.

[0274] Piston contact point θp and clutch contact point θ fThe detection can be performed at any time as long as there is no fault in the driving of the vehicle equipped with the two-stage transmission 1. Specifically, it can be performed at a time when the two-stage transmission 1 is switched from a low reduction ratio mode to a high reduction ratio mode, such as after the ignition switch is turned on, during downshift acceleration, when the engine brake is working, etc.

[0275] However, when the above operation is to be performed while the vehicle is running, there is a problem that the driving cam 34 cannot be driven at an arbitrary rotation speed. f The detection of is preferably performed when the vehicle is stopped, such as after the ignition switch is turned on. f The detection can be performed at a time when the detection can be performed, either each time or when a predetermined time has passed since the last execution.

[0276] When the two-stage transmission 1 of this example switches between the high reduction ratio mode and the low reduction ratio mode, the piston contact point θp detected by the first function and / or the clutch contact point θp detected by the second function are detected. f The rotation amount of the drive cam 34 driven by the shift motor 66 via the speed reducer 67 is adjusted. Specifically, for example, before and after the switching from the high speed reduction ratio mode to the low speed reduction ratio mode, when the rotation torque of the output member 5 is maintained substantially constant, in S1, the clutch touch point θ detected by the second function is used as the target value of the phase in the rotation direction of the drive cam 34. f .

[0277] In the two-stage transmission 1 of this example, as the first friction plate 30 and the second friction plate 31 wear, even at the piston contact point θp and the clutch contact point θ f When the initial position is changed, the piston contact point θp and the clutch contact point θp after correction can also be used to calculate the corrected piston contact point θp and the clutch contact point θp. f Therefore, according to the two-stage transmission 1 of this example, regardless of the wear of the first friction plate 30 and the second friction plate 31, the occurrence of the speed change shock can be prevented.

[0278] The two-stage transmission 1 of this example has the following functions: subject to satisfying a predetermined learning start condition, a mode switch is implemented between a first mode (in this example, a low reduction ratio mode) and a second mode (in this example, a high reduction ratio mode), and in the inertia phase of the mode switch, the friction coefficient between the first friction plate 30 and the second friction plate 31 is calculated based on the output torque of the drive motor 2 and the angular acceleration of the output shaft 11 of the drive motor 2, thereby obtaining a relationship between the friction coefficient and the rotational difference as the difference in rotation number of any two of the above elements (in this example, the sun gear 101 and the ring gear 102), i.e., a μ-V characteristic (a learning method for executing the μ-V characteristic).

[0279] The two-stage transmission 1 in this example has the following functions: when switching the mode between the first mode (in this example, the low reduction ratio mode) and the second mode (in this example, the high reduction ratio mode), based on the above-mentioned μ-V characteristics obtained according to the above-mentioned learning function, the output torque of the drive motor 2 and the magnitude of the force pushing the first friction plate 30 and the second friction plate 31 against each other are controlled (the speed change control method of the two-stage transmission 1 is executed).

[0280] The μ-V characteristic of the friction engagement portion 26 changes with changes in the use environment, such as the oil temperature of the lubricating oil and the surface temperature of the contact portion (sliding portion) between the first friction plate 30 and the second friction plate 31, and with annual degradation. The two-stage transmission 1 of this example performs a learning function to obtain the μ-V characteristic of the friction engagement portion 26 on the condition that a predetermined learning start condition is satisfied, and when switching between the high reduction ratio mode and the low reduction ratio mode, a speed control function is performed to control the output torque of the drive motor 2 in the torque phase and the magnitude of the force that pushes the first friction plate 30 and the second friction plate 31 against each other in the inertia phase, that is, the connecting force F of the friction engagement portion 26, based on the μ-V characteristic obtained by the learning function.

[0281] In the learning function of the two-stage transmission 1 in this example, the difference between the input rotation number and the output rotation number to the friction engagement part 26 (the difference between the rotation number of the first friction plate 30 and the rotation number of the second friction plate 31, the rotation difference) V is used as the difference in the rotation numbers of any two of the above-mentioned elements (in this example, the sun gear 101 and the ring gear 102), that is, the rotation difference.

[0282] The learning start condition can be set to any condition as long as there is no fault during the driving of the vehicle equipped with the two-stage transmission 1 and the two-stage transmission 1 can be switched between the high reduction ratio mode and the low reduction ratio mode. For example, the learning start condition can be implemented when the two-stage transmission 1 is switched from the high reduction ratio mode to the low reduction ratio mode, or when the two-stage transmission 1 is switched from the low reduction ratio mode to the high reduction ratio mode during the driving of the vehicle.

[0283] The μ-V characteristic learning function can be performed each time when the learning function can be performed. Alternatively, changes in the use environment such as a predetermined time having passed since the last execution and / or a change in the oil temperature of the lubricating oil, the surface temperature of the sliding contact portion between the first friction plate 30 and the second friction plate 31, and the outside air temperature exceeding a predetermined temperature can also be included in the learning start condition.

[0284] As the timing for executing the learning function, it is possible to start the mode switching between the high reduction ratio mode and the low reduction ratio mode, i.e., after the execution of the learning function is started, or to execute the learning function after the mode switching, i.e., after the mode switching is started, on the premise of satisfying the predetermined learning conditions.

[0285] Specifically, before and after the above-mentioned mode switching, the mode switching between the high reduction ratio mode and the low reduction ratio mode is performed in a manner that the rotational torque and the number of revolutions Rout of the output member 5 are maintained substantially constant. The μ-V characteristic is learned in the inertia phase of the switching from the high reduction ratio mode to the low reduction ratio mode and / or the switching from the low reduction ratio mode to the high reduction ratio mode. The following describes the case where the μ-V characteristic is learned in the inertia phase of the switching from the high reduction ratio mode to the low reduction ratio mode.

[0286] When the high speed reduction ratio mode is switched to the low speed reduction ratio mode, the phase θ in the rotation direction of the driving cam 34 moves to the clutch contact point θ f Thereafter, when the phase θ in the rotation direction of the driving cam 34 increases, the two-stage transmission 1 switches to the low reduction ratio mode after sequentially passing through the torque phase and the inertia phase.

[0287] like Fig.26 As shown, in the torque phase, the rotation difference V does not change but is maintained constant, whereas the clutch torque Tcl transmitted to the friction engagement portion 26 (via the friction engagement portion 26) increases.

[0288] In the inertia phase, the clutch torque Tcl does not change but remains constant, and the rotation speed Rs of the output shaft 11 of the drive motor 2 begins to decrease. If the rotation speed Rs of the output shaft 11 decreases, the rotation speed Rin of the input member 4 decreases, so the difference between the input rotation speed Rin and the output rotation speed Rout of the friction engagement portion 26, that is, the rotation difference V, decreases.

[0289] If the rotation difference V starts to decrease, that is, the change per unit time dV / dt of the rotation difference V exceeds a predetermined threshold value, it can be determined that the inertia phase has started. Specifically, in this example, based on the output signal of the rotation sensor installed on the output shaft 11 of the drive motor 2, when it is determined that the rotation number Rs of the output shaft 11 has decreased by more than a predetermined value, it is determined that the inertia phase has started.

[0290] In the inertia phase, based on the rotation torque Tin of the input member 4 and the angular acceleration dω of the input member 4 in / dt, the clutch torque Tcl is calculated. The friction coefficient μ between the first friction plate 30 and the second friction plate 31 is calculated based on the clutch torque Tcl and the clutch load Fcl, and the relationship between the friction coefficient μ and the rotation difference V, that is, the μ-V characteristic, is obtained.

[0291] In the two-stage transmission 1 of this example, the clutch torque Tcl [N·m] in the inertia phase can be obtained by the following equation (1).

[0292] (Mathematical formula 1)

[0293]

[0294] In the formula (1), α represents the reduction ratio of the planetary speed change mechanism 9 (= the number of teeth of the sun gear 101 / the number of teeth of the ring gear 102). in The inertia (inertia moment) of the portion connected to the input member 4 is represented by the portion connected to the input member 4. The portion connected to the input member 4 is a portion that rotates integrally with the input member 4 regardless of the mode of the friction engagement device 7 and the mode of the rotation transmission state switching device 8. That is, I in It is the inertia of the combination composed of the input member 4 , the ring gear 102 and the plurality of first friction plates 30 .

[0295] I sun Indicates the inertia of the portion connected to the sun gear 101. The portion connected to the sun gear 101 rotates integrally with the sun gear 101 when the sun gear 101 rotates, and does not rotate when the sun gear 101 does not rotate, regardless of the mode of the friction engagement device 7 and the mode of the rotation transmission state switching device 8. That is, I sun It is the inertia of the combination composed of the rotating member 6 , the sun gear 101 , the plurality of second friction plates 31 , and the first member 71 .

[0296] The clutch torque Tcl in the inertia phase can also be obtained by the following (2).

[0297] (Mathematical formula 2)

[0298] Tcl=μ×Fcl×Rcl…(2)

[0299] In the formula (2), Fcl represents the force of the first friction plate 30 and the second friction plate 31 pressing each other, that is, the clutch load. The clutch load Fcl is related to the phase θ related to the rotation direction of the drive cam 34, and can be obtained by preliminary experiments and calculations at the time of factory shipment, or at the time of shipment and / or inspection of the automobile equipped with the two-stage transmission 1.

[0300] Rcl represents the effective radius of the friction engagement portion 26. The effective radius Rcl can also be set to 1 / 4 of the sum of the outer diameter and the inner diameter of the sliding contact portion of the first friction plate 30 and the second friction plate 31, or can be set to a radius at which the area of ​​the radially outer portion and the area of ​​the radially inner portion of the sliding contact portion of the first friction plate 30 and the second friction plate 31 are equal.

[0301] If equation (2) is transformed, the following equation (3) is obtained.

[0302] (Mathematical formula 3)

[0303]

[0304] Then, by substituting equation (1) into equation (3), the friction coefficient μ can be expressed by the following equation (4).

[0305] (Mathematical formula 4)

[0306]

[0307] In the formula (4), the rotation torque Tin of the input member 4 can be obtained based on the command value (control value) Tmot of the torque generated by the drive motor 2. That is, the rotation torque Tin of the input member 4 can be obtained according to the following formula (5).

[0308] (Mathematical formula 5)

[0309] Tin=β×Tmot…(5)

[0310] In the formula (5), β represents the reduction ratio between the drive gear 12 and the input gear 13 (= the number of teeth of the input gear 13 / the number of teeth of the drive gear 12 ).

[0311] (4) where the angular acceleration dω of the input component 4 is in / dt can be obtained based on the output signal of the rotation speed sensor attached to the input member 4 or the output shaft 11 of the drive motor 2. The clutch load Fcl can be estimated based on the phase θ in the rotation direction of the drive cam 34 from a relationship previously obtained by experiments or calculations.

[0312] As described above, in the inertia phase, the rotation torque Tin of the input member 4 and the angular acceleration dω of the input member 4 can be used to calculate the rotation torque Tin of the input member 4 and the angular acceleration dω of the input member 4. in / dt to calculate the clutch torque Tcl, and the friction coefficient μ between the first friction plate 30 and the second friction plate 31 can be calculated based on the clutch torque Tcl and the clutch load Fcl.

[0313] The rotation difference V can be obtained based on output signals of rotation speed sensors respectively attached to the input member 4 and the output member 5 .

[0314] In the two-stage transmission 1 of this example, in the inertia phase when switching from the high reduction ratio mode to the low reduction ratio mode, the friction coefficient μ and the rotation difference V are obtained at predetermined time intervals, thereby obtaining Fig.42 The μ-V characteristic is stored in a memory of a controller (not shown) as a table or a mathematical expression.

[0315] In reality, the clutch load Fcl also changes year by year due to the influence of the wear of the first friction plate 30 and the second friction plate 31, the deterioration of the elastic member 33 and the return spring 70, etc. However, in the two-stage transmission 1 of this example, as shown in equations (4) and (5), the friction coefficient μ is obtained based on the clutch load Fcl obtained by preliminary experiments and calculations at the time of factory shipment, or at the time of shipment and / or inspection of the automobile equipped with the two-stage transmission 1. Therefore, the μ-V characteristic including the influence of the year-to-year change of the clutch load Fcl can be obtained.

[0316] In the above description, the case where the μ-V characteristic is learned during the inertia phase of switching from the high reduction ratio mode to the low reduction ratio mode is described, but the μ-V characteristic can also be learned during the inertia phase of switching from the low reduction ratio mode to the high reduction ratio mode.

[0317] According to the speed control function of the two-stage transmission 1 of this example, the output torque of the drive motor 2 in the torque phase when switching between the high reduction ratio mode and the low reduction ratio mode and the coupling force F of the friction engagement portion 26 in the inertia phase can be controlled based on the μ-V characteristic obtained by the learning function, thereby controlling the rotational torque of the output member 5. By controlling the coupling force F of the friction engagement portion 26, specifically, the shift motor 66 is controlled, thereby controlling the rotation of the drive cam 34.

[0318] The two-stage transmission 1 of this example can implement speed change control based on the μ-V characteristic corrected for the change amount of the influence, even if the friction coefficient μ of the friction engagement portion 26 changes due to the influence of the change of the use environment, the deterioration over the years, etc. Therefore, according to the two-stage transmission 1 of this example, regardless of the influence of the change of the use environment, the deterioration over the years, etc. on the friction coefficient μ, the generation of speed change shock can be prevented.

[0319] In the two-stage transmission 1 of this example, the speed reduction ratio switching mode is passed through during the switching from the high speed reduction ratio mode to the low speed reduction ratio mode, so that the speed change shock accompanying the mode switching can be suppressed and the torque loss can be suppressed. Fig. 27 as well as Fig.28 The reason is explained.

[0320] Fig. 27 : represents a part of a two-stage transmission of a comparative example. The two-stage transmission of the comparative example comprises: a first friction engagement device 105, which switches whether the input member 4 and the rotating member 6 can rotate relative to each other, in other words, switches whether the ring gear 102 and the sun gear 101 can rotate relative to each other; and a second friction engagement device 106, which switches whether the rotating member 6 can rotate relative to the fixed part 10, in other words, whether the sun gear 101 can rotate. That is, the two-stage transmission of the comparative example adopts the second friction engagement device 106 that switches the mode by pressing or separating the first friction plate 30 and the second friction plate 31, instead of the rotation transmission state switching device 8 of the two-stage transmission of this example.

[0321] In the comparative example, the driving cam 34z of the cam device 28z is rotationally driven by an electric actuator, and the mode of the first friction engagement device 105 and the mode of the second friction engagement device 106 are switched based on the axial displacement of the first driven cam 107 and the second driven cam 108. The first driven cam 107 and the second driven cam 108 move to different phases (displace (advance and retreat) in opposite directions in the axial direction) with the rotation of the driving cam 34z.

[0322] In the two-stage transmission of the comparative example, Fig.28 As shown in the figure, in the switching from the high reduction ratio mode with a large reduction ratio to the low reduction ratio mode with a small reduction ratio, the connection force of the first friction engagement device 105 gradually increases, and the connection force of the second friction engagement device 106 gradually decreases. Therefore, in the switching from the high reduction ratio mode to the low reduction ratio mode, if the connection force of the second friction engagement device 106 gradually decreases and becomes insufficient, the sun gear 101 is pulled and slipped by the revolution of the planetary gear 104, and torque loss occurs between the rotating member 6 and the fixed part 10.

[0323] Even in the two-stage transmission of the comparative example, as the coupling force of the first friction engagement device 105 gradually increases, the torque applied to the sun gear 101 in the direction opposite to the predetermined direction gradually decreases and becomes 0, and then the direction of the torque applied to the sun gear 101 is reversed. However, in the two-stage transmission of the comparative example, at the moment when the direction of the torque applied to the sun gear 101 is reversed and the revolution direction of the planetary gear 104 coincides with the rotation direction of the sun gear 101, the coupling force of the second friction engagement device 106 cannot be sufficiently increased. Therefore, the sun gear 101 is pulled and slid relative to the fixed part 10, and torque loss occurs between the sun gear 101 and the fixed part 10.

[0324] In the two-stage transmission 1 of this example, in order to switch from the high reduction ratio mode to the low reduction ratio mode based on the rotation of the driving cam 34, the rotation transmission state switching device 8 is set to the one-way clutch mode before the friction engagement device 7 starts to switch from the disconnection mode to the connection mode. Therefore, in order to switch the friction engagement device 7 from the disconnection mode to the connection mode, the connection force F of the friction engagement portion 26 is gradually increased, and at the moment when the direction of the torque applied to the sun gear 101 is reversed, the sun gear 101 can be allowed to rotate in the above-mentioned predetermined direction. Therefore, the speed change shock accompanying the mode switching can be suppressed, and the torque loss in the two-stage transmission 1 can be suppressed.

[0325] In a state where the connection force F of the friction engagement portion 26 is small to such an extent that no torque loss occurs in the abutment portion between the axial side surfaces of the first friction plate 30 and the axial side surfaces of the second friction plate 31, the reduction ratio between the input member 4 and the output member 5 in the reduction ratio switching mode is the same as the reduction ratio in the high reduction ratio mode. On the other hand, in a state where the connection force F of the friction engagement portion 26 is increased to such an extent that no slip occurs in the abutment portion between the axial side surfaces of the first friction plate 30 and the axial side surfaces of the second friction plate 31 and the torque can be transmitted, the reduction ratio is the same as that in the low reduction ratio mode, that is, 1.

[0326] When the connection force F of the friction engagement portion 26 causes sliding in the contact portions between the axial side surfaces of the first friction plate 30 and the axial side surfaces of the second friction plate 31, the reduction ratio between the input member 4 and the output member 5 becomes a value corresponding to the magnitude of the input torque, the rotation speed, etc.

[0327] In the state where the input member 4 rotates in the forward direction, in the switching from the high reduction ratio mode to the reduction ratio switching mode, a torque is applied to the second member 72 of the rotation transmission state switching device 8 in the direction opposite to the predetermined direction. Here, in the rotation transmission state switching device 8, the rotation of the second member 72 in the direction opposite to the predetermined direction is also prevented during the switching from the locking mode to the one-way clutch mode. That is, the reduction ratio between the input member 4 and the output member 5 in the switching from the high reduction ratio mode to the reduction ratio switching mode is the same as the reduction ratio in the high reduction ratio mode.

[0328] When the input member 4 rotates in the forward direction, in the switching from the reduction ratio switching mode to the low reduction ratio mode, a torque is applied in the predetermined direction to the second member 72 of the rotation transmission state switching device 8. Here, in the rotation transmission state switching device 8, the second member 72 is also allowed to rotate in the predetermined direction during the switching from the one-way clutch mode to the free mode.

[0329] When the input member 4 rotates in the reverse direction, that is, when the automobile equipped with the two-stage transmission 1 of this example moves backward, the vehicle basically does not travel at a high speed. Therefore, when the input member 4 rotates in the reverse direction, when switching from the high reduction ratio mode to the low reduction ratio mode, the friction engagement device 7 is set to the one-way clutch mode as when rotating in the forward direction, thereby eliminating the need to switch to the reduction ratio switching mode that allows the rotation of the sun gear 101 at the moment when the direction of the torque applied to the sun gear 101 is reversed.

[0330] Even when the input member 4 rotates in the forward direction, the vehicle is mainly in a deceleration state when switching from the low reduction ratio mode to the high reduction ratio mode. In this case, since the power is not transmitted from the input member 4 to the output member 5, there is no need to switch the two-stage transmission 1 to the reduction ratio switching mode.

[0331] According to the two-stage transmission 1 of this example, it is possible to ensure good torque transmission efficiency. The reason for this is described below.

[0332] In a state where the cam device 28 generates a pressing force, that is, in a state where the piston 32 is pressed toward one side in the axial direction by the driven cam 35 via the thrust bearing 57 and the pressing member 58 ( Figure 2 (b)), a force is applied to the thrust bearing 57 toward one axial side. In addition, the reaction force of the driven cam 35 pressing the piston 32 toward one axial side is applied to the radial bearing 38 toward the other axial side via the rolling element 36 and the driving cam 34.

[0333] The raceway ring 59a constituting one axial side of the thrust bearing 57 is supported on the rotating member 6 via the pressing member 58 and the piston 32, and the raceway ring 59b on the other axial side is supported on the fixed portion 10 via the cam device 28, the angular contact ball bearing 39, and the tubular member 37. In addition, the inner ring 42 constituting the radial bearing 38 is externally fitted and fixed to the rotating member 6, and the outer ring 43 is supported on the driving cam 34 of the cam device 28 via the tubular member 37 and the angular contact ball bearing 39.

[0334] In the two-stage transmission 1 of this example, when the cam device 28 generates a pressing force, that is, when the piston 32 is pressed toward one side in the axial direction and the axial dimension of the elastic member 33 is elastically reduced, the force of the first friction plate 30 and the second friction plate 31 pushing each other is released and the friction engagement device 7 is cut off, the rotation transmission state switching device 8 is in the locking mode. In the high reduction ratio mode in which the friction engagement device 7 is cut off and the rotation transmission state switching device 8 is switched to the locking mode, the relative rotation of the rotating member 6 with respect to the fixed part 10 is prevented.

[0335] In this state, the raceway ring 59a on one axial side and the raceway ring 59b on the other axial side of the thrust bearing 57 do not rotate relative to each other, and the inner ring 42 and the outer ring 43 of the radial bearing 38 do not rotate relative to each other. In short, the thrust bearing 57 and the radial bearing 38 are subjected to axial ( Figure 2 (b) in the left and right direction), when the rolling resistance becomes large, the raceway ring 59a on one axial side and the raceway ring 59b on the other axial side of the thrust bearing 57 do not rotate relative to each other, and the inner ring 42 and the outer ring 43 of the radial bearing 38 do not rotate relative to each other. Therefore, the generation of torque loss in the thrust bearing 57 and the radial bearing 38 can be prevented.

[0336] The pressing force generated by the cam device 28 is applied to the rotating member 6 in one axial direction from the driven cam 35 via the pressing member 58 and the thrust bearing 57, the piston 32 and the elastic member 33. In contrast, the reaction force accompanying the pressing force generated by the cam device 28 is applied to the rotating member 6 in the other axial direction from the driving cam 34 via the radial bearing 38. In this way, the axial forces accompanying the pressing force generated by the cam device 28 are mutually offset (negated) in the rotating member 6.

[0337] In the state where the rotation transmission state switching device 8 is switched to the free mode and relative rotation of the rotating member 6 relative to the fixed part 10 is allowed ( Figure 2 In the state shown in (a), the friction engagement device 7 is connected and the cam device 28 does not generate a pressing force. In this state, since the axial force (caused by the cam device 28 generating a pressing force) is not applied to the thrust bearing 57 and the radial bearing 38, Figure 2Therefore, the rolling resistance of the thrust bearing 57 and the radial bearing 38 will not increase suddenly, and the torque loss will not be too large.

[0338] In the two-stage transmission 1 of this example, except for a short time during mode switching, an axial force is applied with the pressing force generated by the cam device 28, and the rolling resistance becomes large. In this state, the thrust bearing 57 and the radial bearing 38 do not rotate. Therefore, it is possible to prevent the generation of excessive torque loss of the thrust bearing 57 and the radial bearing 38, and it is possible to ensure good torque transmission efficiency of the two-stage transmission 1.

[0339] However, the two-stage transmission disclosed in the present invention can also be applied to a structure having a rotation transmission state switching device, which does not have a one-way clutch mode, that is, has only a free mode and a locking mode. In such a modified example, when switching from a high reduction ratio mode to a low reduction ratio mode, such as Fig.29 As shown, after the rotation transmission state switching device is switched from the locking mode to the free mode, the friction engagement device is switched from the disconnecting mode to the connecting mode.

[0340] [Second example]

[0341] Fig.30 The second example of the embodiment of the present disclosure is shown. The two-stage transmission 1 a of this example is different from the two-stage transmission 1 of the first example in that only the arrangement of the friction engagement device 7 a is changed. Specifically, in this example, the friction engagement device 7 a is arranged between the sun gear 101 and the carrier 103 .

[0342] In the two-stage transmission 1a of this example, by setting the rotation transmission state switching device 8 to the free mode and the friction engagement device 7a to the connection mode, when the two-stage transmission 1a is switched to the first mode, the planetary speed change mechanism 9 is in a glued state where the entirety rotates integrally. That is, the torque input to the input member 4 is not increased but is transmitted to the output member 5 as it is.

[0343] In contrast, by setting the rotation transmission state switching device 8 to the lock mode and the friction engagement device 7a to the disconnection mode, when the two-stage transmission 1a is switched to the second mode, the torque input to the input member 4 is increased by the planetary speed change mechanism 9 and then transmitted to the output member 5. Specifically, the rotation torque of the input member 4 is transmitted in the order of the input member 4, the ring gear 102, the rotation motion of the planetary gear 104, the revolution motion of the planetary gear 104 based on the meshing with the sun gear 101, the carrier 103, and the output member 5, and is taken out from the output member 5.

[0344] In this example, the first mode corresponds to a low speed reduction ratio mode in which the speed reduction ratio between the input member 4 and the output member 5 is small, and the second mode corresponds to a high speed reduction ratio mode in which the speed reduction ratio is larger than that in the low speed reduction ratio mode.

[0345] In the two-stage transmission 1a of this example, in the inertia phase of the mode switching between the high reduction ratio mode and the low reduction ratio mode, the friction coefficient μ and the rotation difference V are obtained at predetermined time intervals to obtain the μ-V characteristic. In the two-stage transmission 1a of this example, the friction coefficient μ can be obtained according to the following formula (6).

[0346] (Mathematical formula 6)

[0347]

[0348] The two-stage transmission 1a of this example also controls the output torque of the drive motor 2 in the torque phase and the connection force F of the friction engagement portion 26 in the inertia phase based on the μ-V characteristic obtained by the learning function when switching between the high reduction ratio mode and the low reduction ratio mode, and can prevent the generation of speed change shock regardless of the influence of the change in the use environment, the annual degradation, etc. on the friction coefficient μ. The structure and effects of other parts of the second example are the same as those of the first example.

[0349] [Third example]

[0350] Fig.31 The second transmission 1b of this example also changes only the arrangement of the friction engagement device 7b from the first example and the second example. Specifically, in this example, the friction engagement device 7b is arranged between the ring gear 102 and the carrier 103.

[0351] When the two-stage transmission 1b of this example is switched to the first mode, the planetary speed change mechanism 9 is in a glued state, and the torque input to the input member 4 is not increased, but is transmitted to the output member 5 as it is. On the other hand, when the two-stage transmission 1b is switched to the second mode, the torque input to the input member 4 is increased by the planetary speed change mechanism 9 and then transmitted to the output member 5b.

[0352] In the two-stage transmission 1b of this example, in the inertia phase of the mode switching between the high reduction ratio mode as the second mode and the low reduction ratio mode as the first mode, the friction coefficient μ and the rotation difference V are obtained at predetermined time intervals, thereby obtaining the μ-V characteristic. In the two-stage transmission 1b of this example, the friction coefficient μ can be obtained according to the following formula (7).

[0353] (Mathematical formula 7)

[0354]

[0355] The structure and effects of other parts of the third example are the same as those of the first and second examples.

[0356] [Fourth example]

[0357] Fig.32 The fourth example of the embodiment of the present disclosure is shown. In the two-stage transmission 1c of this example, the input member 4a is connected to the sun gear 101 of the planetary speed change mechanism 9 in a manner that allows torque transmission, and the output member 5a is connected to the carrier 103 in a manner that allows torque transmission. The friction engagement device 7c is arranged between the sun gear 101 and the carrier 103, and the rotation transmission state switching device 8a is arranged between the fixed part 10 and the ring gear 102.

[0358] The two-stage transmission 1c of this example sets the rotation transmission state switching device 8 to the free mode and the friction engagement device 7c to the connection mode, so that when the two-stage transmission 1c is switched to the first mode, the planetary speed change mechanism 9 is in the engaged state. That is, the torque input to the input member 4a is transmitted to the output member 5a as it is.

[0359] By setting the rotation transmission state switching device 8a to the lock mode and the friction engagement device 7c to the disconnection mode, when the two-stage transmission 1c is switched to the second mode, the torque input to the input member 4a is increased by the planetary speed change mechanism 9 and then transmitted to the output member 5a. Specifically, the rotation torque of the input member 4a is transmitted in the order of the input member 4a, the sun gear 101, the rotation motion of the planetary gear 104, the revolution motion of the planetary gear 104 based on the meshing with the ring gear 102, the carrier 103, and the output member 5a, and is taken out from the output member 5a.

[0360] In the two-stage transmission 1c of this example, in the inertia phase of switching from the high reduction ratio mode as the second mode to the low reduction ratio mode as the first mode, the friction coefficient μ and the rotation difference V are obtained at predetermined time intervals, thereby being able to obtain the μ-V characteristic. In the two-stage transmission 1c of this example, the friction coefficient μ can be obtained according to the following formula (8).

[0361] (Mathematical formula 8)

[0362]

[0363] (8) I ringIndicates the inertia of the portion connected to the ring gear 102. The portion connected to the ring gear 102 is a portion that rotates integrally with the ring gear 102 when the ring gear 102 rotates, and does not rotate when the ring gear 102 does not rotate, regardless of the mode of the friction engagement device 7c and the mode of the rotation transmission state switching device 8a. The structure and effects of the other portions of the fourth example are the same as those of the first example.

[0364] [Fifth example]

[0365] Fig.33 The fifth example of the embodiment of the present disclosure is shown. The two-stage transmission 1d of this example is different from the two-stage transmission 1c of the fourth example only in the arrangement of the friction engagement device 7d. Specifically, in this example, the friction engagement device 7d is arranged between the ring gear 102 and the carrier 103.

[0366] In the two-stage transmission 1d of this example, in the inertia phase of the mode switching between the high reduction ratio mode as the second mode and the low reduction ratio mode as the first mode, the friction coefficient μ and the rotation difference V are obtained at predetermined time intervals, thereby obtaining the μ-V characteristic. In the two-stage transmission 1d of this example, the friction coefficient μ can be obtained according to the following formula (9).

[0367] (Mathematical formula 9)

[0368]

[0369] The structure and effects of other parts of the fifth example are the same as those of the first and fourth examples.

[0370] [Sixth example]

[0371] Fig.34 The sixth example of the embodiment of the present disclosure is shown. In the two-stage transmission 1e of this example, only the configuration of the friction engagement device 7e is changed from the two-stage transmission 1c of the fourth example and the two-stage transmission 1d of the fifth example. Specifically, in this example, the friction engagement device 7e is configured between the sun gear 101 and the ring gear 102.

[0372] In the two-stage transmission 1e of this example, in the inertia phase of the mode switching between the high reduction ratio mode as the second mode and the low reduction ratio mode as the first mode, the friction coefficient μ and the rotation difference V are obtained at predetermined time intervals, thereby obtaining the μ-V characteristic. In the two-stage transmission 1e of this example, the friction coefficient μ can be obtained according to the following formula (10).

[0373] (Mathematical formula 10)

[0374]

[0375] The structure and effects of other parts of the sixth example are the same as those of the first and fourth examples.

[0376] [Seventh Example]

[0377] Fig.35 The seventh example of the embodiment of the present disclosure is shown. In the two-stage transmission 1f of this example, the planetary speed change mechanism 9a is composed of a double pinion type planetary gear mechanism. That is, the planetary speed change mechanism 9a has a plurality of planetary gears 104a on the inner diameter side meshing with the sun gear 101a, and a plurality of planetary gears 104b on the outer diameter side meshing with the ring gear 102a, so that the planetary gears 104a on the inner diameter side and the planetary gears 104b on the outer diameter side mesh with each other, and are rotatably supported on the carrier 103a.

[0378] In this example, the input member 4b is connected to the carrier 103a in a torque-transmitting manner, and the output member 5b is connected to the ring gear 102a in a torque-transmitting manner. The friction engagement device 7f is arranged between the sun gear 101a and the carrier 103a, and the rotation transmission state switching device 8b is arranged between the fixed part 10 and the sun gear 101a.

[0379] The two-stage transmission 1f of this example sets the rotation transmission state switching device 8b to the free mode and the friction engagement device 7f to the connection mode, so that when the two-stage transmission 1f is switched to the first mode, the planetary speed change mechanism 9a is in the engaged state. That is, the torque input to the input member 4b is transmitted to the output member 5b as it is.

[0380] By setting the rotation transmission state switching device 8b to the lock mode and the friction engagement device 7f to the disconnection mode, when the two-stage transmission 1f is switched to the second mode, the torque input to the input member 4b is increased by the planetary speed change mechanism 9a and then transmitted to the output member 5b. Specifically, the rotation torque of the input member 4b is transmitted in the order of the input member 4b, the carrier 103a, the revolution motion of the planetary gears 104a and 104b, the rotation motion of the planetary gear 104a on the inner diameter side due to the meshing with the sun gear 101a, the rotation motion of the planetary gear 104b on the outer diameter side, the ring gear 102a, and the output member 5b, and is taken out from the output member 5b.

[0381] In the two-stage transmission 1f of this example, in the inertia phase of the mode switching between the high reduction ratio mode as the second mode and the low reduction ratio mode as the first mode, the friction coefficient μ and the rotation difference V are obtained at predetermined time intervals, thereby obtaining the μ-V characteristic. In the two-stage transmission 1f of this example, the friction coefficient μ can be obtained according to the following formula (11).

[0382] (Mathematical formula 11)

[0383]

[0384] The structure and effects of other parts of the seventh example are the same as those of the first example.

[0385] [Example 8]

[0386] Fig.36 The eighth example of the embodiment of the present disclosure is shown. The two-stage transmission 1g of this example is different from the two-stage transmission 1f of the seventh example only in the arrangement of the friction engagement device 7g. Specifically, in this example, the friction engagement device 7g is arranged between the ring gear 102a and the carrier 103a.

[0387] In the two-stage transmission 1g of this example, in the inertia phase of the mode switching between the high reduction ratio mode as the second mode and the low reduction ratio mode as the first mode, the friction coefficient μ and the rotation difference V are obtained at predetermined time intervals, thereby obtaining the μ-V characteristic. In the two-stage transmission 1g of this example, the friction coefficient μ can be obtained according to the following formula (12).

[0388] (Mathematical formula 12)

[0389]

[0390] The structure and effects of other parts of the eighth example are the same as those of the first and seventh examples.

[0391] [Case 9]

[0392] Fig.37 The ninth example of the embodiment of the present disclosure is shown. The two-stage transmission 1h of this example is different from the two-stage transmission 1f of the seventh example and the two-stage transmission 1g of the eighth example only in the configuration of the friction engagement device 7h. Specifically, in this example, the friction engagement device 7h is configured between the sun gear 101a and the ring gear 102a.

[0393] In the two-stage transmission 1h of this example, in the inertia phase of the mode switching between the high reduction ratio mode as the second mode and the low reduction ratio mode as the first mode, the friction coefficient μ and the rotation difference V are obtained at predetermined time intervals, thereby obtaining the μ-V characteristic. In the two-stage transmission 1h of this example, the friction coefficient μ can be obtained according to the following formula (13).

[0394] (Mathematical formula 13)

[0395]

[0396] The structure and effects of other parts of the ninth example are the same as those of the first and seventh examples.

[0397] [Example 10]

[0398] Fig.38 The tenth example of the embodiment of the present disclosure is shown. In the two-stage transmission 1i of this example, the input member 4c is connected to the sun gear 101a of the planetary speed change mechanism 9a in a manner capable of transmitting torque, and the output member 5c is connected to the ring gear 102a in a manner capable of transmitting torque. The friction engagement device 7i is arranged between the sun gear 101a and the carrier 103a, and the rotation transmission state switching device 8c is arranged between the fixed part 10 and the carrier 103a.

[0399] The two-stage transmission 1i of this example sets the rotation transmission state switching device 8c to the free mode and the friction engagement device 7i to the connection mode, so that when the two-stage transmission 1i is switched to the first mode, the planetary speed change mechanism 9a is in the engaged state. That is, the torque input to the input member 4c is transmitted to the output member 5c as it is.

[0400] In contrast, by setting the rotation transmission state switching device 8c to the lock mode and the friction engagement device 7i to the disconnection mode, when the two-stage transmission 1i is switched to the second mode, the torque input to the input member 4c is increased by the planetary speed change mechanism 9a and then transmitted to the output member 5c. Specifically, the rotation torque of the input member 4c is transmitted in the order of the input member 4c, the sun gear 101a, the rotational motion of the planetary gear 104a on the inner diameter side, the rotational motion of the planetary gear 104b on the outer diameter side, the ring gear 102a, and the output member 5c, and is taken out from the output member 5c.

[0401] In the two-stage transmission 1i of this example, in the inertia phase of the mode switching between the high reduction ratio mode as the second mode and the low reduction ratio mode as the first mode, the friction coefficient μ and the rotation difference V are obtained at predetermined time intervals, thereby obtaining the μ-V characteristic. In the two-stage transmission 1i of this example, the friction coefficient μ can be obtained according to the following formula (14).

[0402] (Mathematical formula 14)

[0403]

[0404] (14) I carrierThe inertia of the part connected to the carrier 103a is shown. The part connected to the carrier 103a is a part that rotates together with the carrier 103a when the carrier 103a rotates, and does not rotate when the carrier 103a does not rotate, regardless of the mode of the friction engagement device 7i and the mode of the rotation transmission state switching device 8c. The structure and effects of the other parts of the tenth example are the same as those of the first and seventh examples.

[0405] [Case 11]

[0406] Fig.39 The eleventh example of the embodiment of the present disclosure is shown. The two-stage transmission 1j of this example is different from the two-stage transmission 1i of the tenth example only in the arrangement of the friction engagement device 7j. Specifically, in this example, the friction engagement device 7j is arranged between the ring gear 102a and the carrier 103a.

[0407] In the two-stage transmission 1j of this example, in the inertia phase of the mode switching between the high reduction ratio mode as the second mode and the low reduction ratio mode as the first mode, the friction coefficient μ and the rotation difference V are obtained at predetermined time intervals, thereby obtaining the μ-V characteristic. In the two-stage transmission 1j of this example, the friction coefficient μ can be obtained according to the following formula (15).

[0408] (Mathematical formula 15)

[0409]

[0410] The structure and effects of other parts of the eleventh example are the same as those of the first and tenth examples.

[0411] [Example 12]

[0412] Fig.40 The twelfth example of the embodiment of the present disclosure is shown. The two-stage transmission 1k of this example is different from the two-stage transmission 1i of the tenth example and the two-stage transmission 1j of the eleventh example only in that the friction engagement device 7k is arranged. Specifically, in this example, the friction engagement device 7k is arranged between the sun gear 101a and the ring gear 102a.

[0413] In the two-stage transmission 1k of this example, in the inertia phase of the mode switching between the high reduction ratio mode as the second mode and the low reduction ratio mode as the first mode, the friction coefficient μ and the rotation difference V are obtained at predetermined time intervals, thereby obtaining the μ-V characteristic. In the two-stage transmission 1k of this example, the friction coefficient μ can be obtained according to the following formula (16).

[0414] (Mathematical formula 16)

[0415]

[0416] The structure and effects of other parts of the twelfth example are the same as those of the first and tenth examples.

[0417] Explanation of symbols

[0418] 1. 1a to 1k—two-stage transmission, 2—drive motor, 3—differential device, 4. 4a to 4c—input member, 5. 5a to 5c—output member, 6—rotating member, 7. 7a to 7k—friction engagement device, 8. 8a to 8c—rotation transmission state switching device, 9. 9a—planetary speed change mechanism, 10—fixed portion, 11—output shaft, 12—drive gear, 13—input gear, 14—output gear, 15—small-diameter flange portion, 16—flange portion, 17—through hole, 18—first circular portion, 19—first cylindrical portion, 20—second circular portion, 21—second cylindrical portion, 22—shaft member, 23—stepped cylindrical member, 24—small-diameter cylindrical portion, 25—female spline portion, 26—friction engagement portion, 2 7—elastic force-applying member, 28, 28z—cam device, 29—electric actuator, 30—first friction plate, 31—second friction plate, 32—piston, 33—elastic member, 34, 34z—driving cam, 35—driven cam, 36—rolling element, 37—tubular member, 38—radial bearing, 39—angular contact ball bearing, 40—cylindrical portion, 41—outward flange portion, 42—inner ring, 43—outer ring, 44—rolling element, 45—inner ring, 46—outer ring, 47—ball, 48—driving cam surface, 48a—first bottom, 48b—first inclined surface portion, 48c—first flat surface portion, 48d—second inclined surface portion, 48e—second bottom, 48f—third inclined surface portion, 48g—second flat surface part, 48h—fourth inclined surface part, 49—worm gear tooth, 50—pin part, 51—female spline part, 52—male spline part, 53—rectangular hole, 54a, 54b—support plate part, 55—support hole, 56—support recess, 57—thrust bearing, 58—pressing part, 59a, 59b—track ring, 60—rolling element, 61—preload giving mechanism, 62—base, 63—partial cylindrical part, 64—support shaft, 65—roller, 66—shift motor, 67—reducer, 68—worm, 69a, 69b—support bearing, 70—return spring, 71—first part, 72—second part, 73—mode selection part, 74—engagement recess, 75—convex part, 76—concave and convex part, 77—outer diameter side concave and convex engagement , 78—inner diameter side concave-convex engaging portion, 79—inner diameter side concave-convex engaging portion, 80—base, 81—cylindrical portion, 82—first retaining recess, 83—second retaining recess, 84a, 84b—spring retaining portion, 85a, 85b—seat portion, 86—first claw member, 87—second claw member, 88—first claw force member, 89—second claw force member, 90—first base, 91—first engaging claw, 92—annular convex portion, 93—second base, 94—second engaging claw, 95—base, 96—plate side engaging hole, 97—protrusion, 98—concave-convex portion, 99—cover body, 100—retaining ring, 101, 101a—sun gear, 102, 102a—ring gear, 103, 103a—carrier,104, 104a, 104b—planetary gears, 105—first friction engagement device, 106—second friction engagement device, 107—first driven cam, 108—second driven cam.

Claims

1. A two-stage transmission, characterized in that: The invention is provided with a planetary speed change mechanism, an input member, an output member, a drive motor, a rotation transmission state switching device, and a friction engagement device. The planetary speed change mechanism comprises an input element connected to the input member, an output element connected to the output member and rotatable relative to the input element, and a rotating element rotatable relative to the input element and the output element. The planetary transmission mechanism comprises a sun element, a ring element supported around the sun element so as to be rotatable relative to the sun element, a carrier element supported so as to be rotatable relative to the sun element and the ring element, and a plurality of planetary elements engaged with the carrier element so as to transmit torque to the sun element and the ring element and rotatably supported on the carrier element. The input element is composed of any one of the sun element, the ring element, and the carrier element. The output element is any one of the sun element, the ring element, and the carrier element, and is composed of elements different from the input element. The rotating element is composed of the remaining elements of the sun element, the ring element, and the carrier element except the input element and the output element. The drive motor drives the input member to rotate directly or via a speed reducer. The rotation transmission state switching device is arranged between the rotating element and a fixed part which does not rotate during use, and switches between a free mode in which the rotating element can rotate relative to the fixed part and a locked mode in which the rotating element cannot rotate. The friction engagement device comprises at least one first friction plate and at least one second friction plate supported in a manner capable of axial relative displacement, and arranged between any two of the sun element, the ring element, and the carrier element. By pushing the first friction plate and the second friction plate against each other, a connection mode is switched to allow the two elements to rotate as a whole. By releasing the force pushing the first friction plate and the second friction plate against each other, a disconnection mode is switched to allow the two elements to rotate relative to each other. The invention has a first mode in which the rotation transmission state switching device is set to the free mode and the friction engagement device is set to the connection mode, and a second mode in which the rotation transmission state switching device is set to the lock mode and the friction engagement device is set to the disconnection mode, and The learning function is as follows: a mode switch is implemented between the first mode and the second mode on the condition that a predetermined learning start condition is satisfied; in the inertia phase of the mode switch, the friction coefficient between the first friction plate and the second friction plate is calculated based on the output torque of the drive motor and the angular acceleration of the output shaft of the drive motor, thereby obtaining a μ-V characteristic which is the relationship between the friction coefficient and the difference in the number of rotations between any two elements, i.e., the rotation difference.

2. The two-stage transmission according to claim 1, characterized in that: When executing the above-mentioned learning function, the rotation number of the output shaft of the above-mentioned drive motor is set to be constant. After starting the mode switching between the above-mentioned first mode and the above-mentioned second mode, it is determined that the above-mentioned inertia stage has started, based on the condition that the change per unit time of the above-mentioned rotation difference exceeds a predetermined threshold value.

3. The two-stage transmission according to claim 1 or 2, characterized in that: The control function includes controlling the output torque of the drive motor and the magnitude of the force pressing the first friction plate and the second friction plate against each other based on the μ-V characteristic obtained by the learning function when switching between the first mode and the second mode.

4. The two-stage transmission according to any one of claims 1 to 3, characterized in that: The friction engagement device comprises: an elastic force applying member which elastically applies force in a direction of pushing the first friction plate and the second friction plate against each other; A cam device having a driving cam and a driven cam supported in a manner capable of relative rotation and axial relative displacement relative to the driving cam, wherein the driven cam is relatively displaced in a direction in which the axial interval between the driven cam and the driving cam is expanded as the driving cam rotates, and the elastic urging member is pressed in a direction in which the force pressing the first friction plate and the second friction plate against each other is released; as well as The electric actuator includes a shift motor and a shift speed reducer, and the drive cam is rotationally driven by the shift motor via the shift speed reducer.

5. The two-stage transmission according to claim 4, characterized in that: The friction engagement device includes a return spring that elastically urges the first friction plate and the second friction plate in a direction in which the first friction plate and the second friction plate are separated from each other.

6. The two-stage transmission according to any one of claims 1 to 5, characterized in that: The rotation transmission state switching device has a one-way clutch mode that allows the rotation element to rotate only in a predetermined direction relative to the fixed portion and prevents the rotation element from rotating in a direction opposite to the predetermined direction relative to the fixed portion.

7. The two-stage transmission according to claim 6, characterized in that: The device has a function of setting the rotation transmission state switching device to the one-way clutch mode while the friction engagement device is switched from the disconnecting mode to the connecting mode and / or while the friction engagement device is switched from the connecting mode to the disconnecting mode.

8. A method for learning the μ-V characteristics of a two-stage transmission, characterized in that: The two-stage transmission includes a planetary speed change mechanism, an input member, an output member, a drive motor, a rotation transmission state switching device, and a friction engagement device. The planetary speed change mechanism comprises an input element connected to the input member, an output element connected to the output member and rotatable relative to the input element, and a rotating element rotatable relative to the input element and the output element. The planetary transmission mechanism comprises a sun element, a ring element supported around the sun element so as to be rotatable relative to the sun element, a carrier element supported so as to be rotatable relative to the sun element and the ring element, and a plurality of planetary elements engaged with the carrier element so as to transmit torque to the sun element and the ring element and rotatably supported on the carrier element. The input element is composed of any one of the sun element, the ring element, and the carrier element. The output element is any one of the sun element, the ring element, and the carrier element, and is composed of elements different from the input element. The rotating element is composed of the remaining elements of the sun element, the ring element, and the carrier element except the input element and the output element. The drive motor drives the input member to rotate directly or via a speed reducer. The rotation transmission state switching device is arranged between the rotating element and a fixed part which does not rotate during use, and switches between a free mode in which the rotating element can rotate relative to the fixed part and a locked mode in which the rotating element cannot rotate. The friction engagement device comprises at least one first friction plate and at least one second friction plate supported in a manner capable of axial relative displacement, and arranged between any two of the sun element, the ring element, and the carrier element. By pushing the first friction plate and the second friction plate against each other, a connection mode in which the two elements rotate as one is switched, and by releasing the force pushing the first friction plate and the second friction plate against each other, a disconnection mode in which the two elements rotate relative to each other is switched. The invention has a first mode in which the rotation transmission state switching device is set to the free mode and the friction engagement device is set to the connection mode, and a second mode in which the rotation transmission state switching device is set to the lock mode and the friction engagement device is set to the disconnection mode. In the above two-stage transmission, On the condition that a predetermined learning start condition is satisfied, a mode switch is implemented between the first mode and the second mode. In the inertia phase of the mode switch, the friction coefficient between the first friction plate and the second friction plate is calculated based on the output torque of the drive motor and the angular acceleration of the output shaft of the drive motor, thereby obtaining a μ-V characteristic which is the relationship between the friction coefficient and the difference in the number of rotations between any two of the above elements, i.e., the rotation difference.

9. A speed control method for a two-stage transmission, The two-stage transmission includes an input member, an output member, a planetary speed change mechanism, a drive motor, a rotation transmission state switching device, and a friction engagement device. The planetary speed change mechanism comprises an input element connected to the input member, an output element connected to the output member and rotatable relative to the input element, and a rotating element rotatable relative to the input element and the output element. The planetary transmission mechanism comprises a sun element, a ring element supported around the sun element so as to be rotatable relative to the sun element, a carrier element supported so as to be rotatable relative to the sun element and the ring element, and a plurality of planetary elements engaged with the carrier element so as to transmit torque to the sun element and the ring element and rotatably supported on the carrier element. The input element is composed of any one of the sun element, the ring element, and the carrier element. The output element is any one of the sun element, the ring element, and the carrier element, and is composed of elements different from the input element. The rotating element is composed of the remaining elements of the sun element, the ring element, and the carrier element except the input element and the output element. The drive motor drives the input member to rotate directly or via a speed reducer. The rotation transmission state switching device is arranged between the rotating element and a fixed part which does not rotate during use, and switches between a free mode in which the rotating element can rotate relative to the fixed part and a locked mode in which the rotating element cannot rotate. The friction engagement device comprises at least one first friction plate and at least one second friction plate supported in a manner capable of axial relative displacement, and arranged between any two of the sun element, the ring element, and the carrier element. By pushing the first friction plate and the second friction plate against each other, a connection mode is switched to the mode in which the two elements rotate as one, and by releasing the force pushing the first friction plate and the second friction plate against each other, a disconnection mode is switched to the mode in which the two elements rotate relative to each other. The invention has a first mode in which the rotation transmission state switching device is set to the free mode and the friction engagement device is set to the connection mode, and a second mode in which the rotation transmission state switching device is set to the lock mode and the friction engagement device is set to the disconnection mode. The speed change control method of the two-stage transmission is characterized by comprising the following steps: According to the μ-V characteristic learning method of claim 8, the μ-V characteristic learning step is obtained; and A step of controlling the output torque of the drive motor and the magnitude of the force pressing the first friction plate and the second friction plate against each other based on the μ-V characteristic obtained in the learning step when the mode is switched between the first mode and the second mode.

Images