Two-stage transmission for electric vehicles

Abstract

A two-stage transmission for an electric vehicle includes a planetary gear mechanism (16) coaxially arranged between an input shaft (10) and an output shaft (12), a friction brake (28), and a friction clutch (26), which is set to a one-stage by coupling of the friction brake (28) and to a 1:1 two-stage by coupling of the friction clutch (26). An electric actuator (30) for switching the one-stage and the two-stage includes an electric control motor (32), a torque-thrust conversion mechanism (36), and a pusher (34). The torque-thrust conversion mechanism (36) is constituted by an inner cylindrical screw (40) driven by rotation of the control motor (32) and an outer cylindrical nut (42) screwed to the cylindrical screw (40) and linked to the pusher (34) in a one-body shaft moving manner. The control motor (32) can include an electromagnetic brake for coupling retention of the friction brake (28) and the friction clutch (26). An axial thrust can also be transmitted by oscillation of an arm (316).

Description

Technical Field

[0001] This invention relates to a two-stage transmission for electric vehicles. Background Technology

[0002] In electric vehicles (EVs), including hybrid vehicles that switch between or share an engine and an electric motor, and vehicles that rely solely on the electric motor for propulsion, the transmission of power from the electric motor to the axle is typically handled by a gearbox, not a transmission with different stages on the rotating shaft. Instead, a reducer is used to reduce the rotational speed of the drive motor to a suitable speed for driving. This is because a key selling point of EVs is that the electric motor can generate driving torque from its non-rotational range, allowing for a wider operating range and a simpler structure; therefore, there is no need for a complex transmission.

[0003] However, while there are advantages to using a transmission in EVs, even electric transmissions struggle to maintain high efficiency across the entire rotational range, particularly in the high-rotational-range where efficiency deteriorates and high speeds are difficult to achieve. To address this, various methods have been proposed to configure a two-stage transmission between the drive motor and the reducer. In this approach, by using the high gear ratio side of the two-stage transmission in the high-rotational-range where efficiency deteriorates, the speed of the drive motor is reduced, allowing it to operate efficiently and thus achieving high speeds. As such a two-stage transmission, various schemes have been proposed using a planetary gear mechanism as the transmission mechanism, with the planetary gear mechanism configured to have a relatively low gear ratio in the first stage and a relatively high gear ratio in the second stage. Among these, an electric actuator consisting of an armature formed of a soft magnetic material, a spring, and an electromagnetic coil has been proposed (Patent Document 1) for switching between the dog clutch (or friction clutch) of the first stage and the friction clutch of the second stage. That is, in the first stage, the dog clutch is engaged by the armature under the force of the spring, and in the second stage, the armature is driven by the electromagnetic coil, thereby setting the dog clutch (or friction clutch) to be disengaged, and setting the friction clutch used in the second stage to be engaged.

[0004] As another type of electric actuator, an electric actuator is also proposed, comprising an electrically rotary control motor and a torque-thrust conversion mechanism. The torque-thrust conversion mechanism consists of an inner-diameter piston, which includes an outer circumferential threaded strip. This outer threaded strip causes the control motor to engage with the inner circumferential threaded strip of the worm wheel via the worm gear. The torque-thrust conversion mechanism converts the rotation (torque) of the control motor into axial thrust of the piston, thereby enabling switching between a first-stage friction clutch and a second-stage friction clutch (Patent Document 2). In the technology of Patent Document 2, the rotation of the worm driven by the control motor is transmitted to the worm wheel, and the rotation of the worm wheel is converted into axial back-and-forth movement of the piston, thereby selectively driving the first and second friction clutches, enabling switching between the first and second stages achieved by a planetary gear mechanism. Existing technical documents Patent documents

[0005] Patent Document 1: Japanese Patent No. 6545921 Patent Document 2: Japanese Patent No. 6028507 Summary of the Invention The technical problem that the invention aims to solve

[0006] Because Patent Document 1 uses a dog-tooth clutch as the first stage, the first stage can be held using spring force, which saves on actuator power consumption. However, during the transition from the second stage to the first stage, the synchronization of the dog-tooth clutch cannot be maintained. Therefore, control is needed to prevent torque increase and other issues from causing shift shock. Furthermore, due to the torque increase, regenerative control is not possible, which is detrimental to combustion efficiency. In addition, for a smooth switching operation, precise control of the engagement capacity is required at the initial stage of clutch switching, but this cannot be achieved in the control of the armature by the electromagnetic coil, which is subject to a significant increase in electromagnetic attraction due to the shortened distance.

[0007] The torque-thrust conversion method in Patent Document 2 avoids the shift shock associated with a dog clutch. Furthermore, by controlling the torque of the electric motor, the engagement capacity of the friction clutch can be appropriately controlled according to the operating state, thus resolving the aforementioned drawbacks of the dog clutch method. However, the torque-thrust conversion method in Reference 2 converts the rotation of the worm gear on the outer diameter side into the linear motion of the piston on the inner diameter side. In this method, a support mechanism for the rolling and thrust of the rotating worm gear relative to the housing is essential. This structure is not described in Patent Document 2, but the use of angular contact ball bearings capable of withstanding rolling and thrust is common knowledge. In a worm gear structure located on the outer diameter side, angular contact ball bearings would inevitably be larger. Using angular contact ball bearings not only increases the outer diameter of the transmission but also the shaft length, making it unsuitable as a component for EVs, which strongly require miniaturization.

[0008] The object of the present invention is to solve the problems described above. Furthermore, the object of the present invention is to form a miniaturized structure suitable for a planetary gear type two-stage transmission including a torque-thrust conversion mechanism driven by an electrically rotary control motor, particularly for the purposes of miniaturization and energy saving. Technical solutions adopted to solve technical problems

[0009] This invention relates to a two-stage transmission for electric vehicles, wherein the two-stage transmission for electric vehicles uses an electric rotary drive motor for driving the wheels, and wherein the two-stage transmission for electric vehicles comprises: shell; The input shaft is supported in the housing and connected to the electric rotary drive motor. The output shaft is supported by the housing and connected to the wheel side; The first gear mechanism is composed of gears that mesh with the output shaft to obtain a first-stage speed ratio when connected to the input shaft. The second gear mechanism is composed of gears that mesh with the output shaft to obtain a second-stage gear ratio that has the same direction of rotation but a higher gear ratio than the first-stage gear ratio when connected to the input shaft. The first multi-plate friction clutch, when engaged, transmits the rotation of the input shaft to the first gear mechanism to obtain the first-stage gear ratio; The second multi-plate friction clutch, which is coaxial with and axially separated from the first multi-plate friction clutch, achieves a second-stage gear ratio by transmitting the rotation of the input shaft to a second gear mechanism during engagement; and The actuator selectively engages the first multi-plate friction clutch and the second multi-plate friction clutch. The actuator includes: a control motor as a torque source; meshing gears for torque transmission; an inner diameter member and an outer diameter member for converting torque into thrust; a thrust transmission member for transmitting thrust; and a clutch pressing member (push member), wherein the clutch pressing member presses a first multi-plate friction clutch and / or a second multi-plate friction clutch for engagement by thrust, and the inner diameter member receives torque from the gears for torque transmission, and the outer diameter member is slidably supported on the housing while preventing rotation, so as to convert the torque applied to the inner diameter member into thrust.

[0010] A single set of actuators can be used for switching between the first and second multi-plate friction clutches. In this case, selective engagement of the first and second multi-plate friction clutches is achieved by moving the clutch pressing member axially back and forth integrally with the outer diameter member via the thrust transmission member. The outer diameter member and the thrust transmission member can be configured as a double-layered cylindrical body consisting of an inner cylindrical portion concentric with the central axis of the transmission, an outer cylindrical portion, and a radial wall portion integrally connecting them. The inner cylindrical portion is screwed onto the outer side of the first and second multi-plate friction clutches on the central axis, and the outer cylindrical portion slides freely onto the inner circumferential surface of the housing while facing the first or second multi-plate friction clutch located on the proximity side. The clutch pressing member is integrally connected to the outer cylindrical portion so as to be located between the first and second multi-plate friction clutches.

[0011] As another method of using a shared set of actuators for the engagement of the first and second multi-plate friction clutches, the thrust transmission member rotates (oscillates) back and forth by the axial back-and-forth movement of the outer diameter member. Through this rotation, the clutch pressing member can selectively engage the first and second multi-plate friction clutches. The thrust transmission member is configured to pivotally connect to the housing at one end and to be fitted with a swing arm of the outer diameter member (nut) at a diameter-opposite position at the other end. The clutch pressing member is pivotally connected to the swing arm at the diameter-opposite position and is located between the opposing faces of the first and second multi-plate friction clutches. The back-and-forth rotation of the swing arm, caused by the axial back-and-forth movement of the internal thread member, engages the clutch pressing member while simultaneously facing and engaging either the first or second multi-plate friction clutch.

[0012] The first gear mechanism and the first gear transmission mechanism can be constructed from planetary gear transmission mechanisms. In a planetary gear transmission mechanism, the input shaft and the output shaft are coaxially arranged within a housing, and the mechanism includes three rotating elements: a gear carrier that supports a pinion and two gears with different numbers of teeth that mesh with the pinion. Two of these elements include planetary gear mechanisms for connecting the input shaft and the output shaft, respectively. The arrangement of the first multi-plate friction clutch and the second multi-plate friction clutch relative to the three rotating elements and the housing is such that a first-stage gear ratio is obtained between the input shaft and the output shaft through the engagement of the first multi-plate friction clutch, which is achieved by a thrust transmission member, and the disengagement of the second multi-plate friction clutch. Thus, a planetary gear transmission mechanism is constructed in the first gear mechanism. To obtain a second-stage gear ratio with the same rotational direction between the input shaft and the output shaft through the disengagement of the first multi-plate friction clutch, which is achieved by a thrust transmission member, and the engagement of the second multi-plate friction clutch, a planetary gear transmission mechanism can be constructed in the second gear mechanism. Furthermore, without using a planetary gear transmission mechanism, the first gear mechanism and the planetary gears of the first gear mechanism are composed of spur gears that mesh to obtain the first-stage transmission ratio, and the second gear mechanism is composed of spur gears that mesh to obtain the second-stage transmission ratio.

[0013] In addition, two sets of actuators are provided, the first set of which is involved in the engagement and disengagement of the first multi-plate friction clutch for setting the gear ratio of the first stage, and the second set of which is involved in the engagement and disengagement of the second multi-plate friction clutch.

[0014] Furthermore, the two-stage transmission of the present invention can also be additionally used for selectively braking the electromagnetic brake of the rotating shaft of the control motor. When the first and second multi-plate friction clutches are engaged, the electromagnetic brake brakes and restricts the rotating shaft of the control motor, maintaining the engagement state of the first and second multi-plate friction clutches at low rotational torque of the control motor. Then, by braking the rotating shaft of the control motor at regular intervals, the first and second multi-plate friction clutches can be re-engaged respectively.

[0015] Furthermore, in this invention, when the first-stage gear ratio and the second gear mechanism are changed by selectively engaging the first multi-plate friction clutch and the second multi-plate friction clutch, a one-way clutch can be provided in parallel with the multi-plate friction clutch participating in the first-stage gear ratio. Invention Effects

[0016] In the two-stage transmission of this invention, the torque-thrust conversion mechanism in the motor-controlled actuator for switching the gear ratio of the planetary gear mechanism, using a meshing thread method, switches between the first and second multi-plate friction clutches by rotating the inner diameter member (screw) and axially moving the outer diameter member (nut). Since the rotating inner diameter member is small-diameter, the torque-thrust conversion mechanism can be miniaturized, and the thrust generated in the inner diameter member can be reduced, allowing for a simpler bearing mechanism. Furthermore, appropriate switching control of the friction clutch or friction brake corresponding to the operating state can be performed without compromising the benefits of motor control such as energy saving.

[0017] By setting the inner and outer diameter components of the torque-thrust conversion mechanism as double-layered cylindrical structures, and by arranging the inner shape portion of the outer diameter component and the threaded portion of the inner diameter component on the outside of the first and second multi-plate friction clutches, the shaft length of the shaft-mounted portion of the torque-thrust conversion mechanism can be suppressed, thereby achieving miniaturization.

[0018] Furthermore, by including an electromagnetic brake as a control motor, it is possible to maintain the connection between the first multi-plate friction clutch and the second multi-plate clutch, to minimize the normal torque of the control motor, to achieve power saving, to suppress the heat generation of the motor, and to simplify the cooling device.

[0019] Furthermore, the switching action achieved by using a combination of one-way clutches allows for smooth operation during coasting by engaging only a multi-plate clutch, enabling shock-free gear changes without torque increase. Consequently, it can switch to electric regeneration, achieving energy savings and improved efficiency.

[0020] By setting up two sets of actuators and connecting the first multi-plate friction clutch and the second multi-plate friction clutch respectively, the idle period during which the pusher moves between the first multi-plate friction clutch and the second multi-plate friction clutch during switching can be eliminated, thus achieving labor-saving control of the motor and eliminating the need for a one-way clutch. Attached Figure Description

[0021] Figure 1 This is a schematic diagram illustrating the wheel drive system of the electric vehicle of the present invention. Figure 2 This is a schematic diagram of the overall structure of a two-stage transmission according to an embodiment of the present invention. Figure 3 It is used for Figure 2 A schematic diagram of an example of a one-way clutch in a two-stage transmission, which is along... Figure 2 A view of the approximate line III-III. Figure 4 yes Figure 2 The diagram shown in section A is a schematic enlarged view, which schematically represents the engagement state between the cylindrical screw and the cylindrical nut in the torque-axial thrust conversion mechanism. Figure 5 yes Figure 2 A schematic enlarged view of part B, which schematically shows the spline connection between the pusher and the housing. Figure 6 yes Figure 2 A diagram illustrating the operation of the actuator. Figure 6 (A) represents the origin position of the actuator. Figure 6 (B) indicates the connection position of the friction brake. Figure 6 (C) indicates the engagement position of the friction clutch. Figure 7 It is a graph showing the relationship between the rotation angle of the control motor and the stroke of the pusher. Figure 8 This is an explanatory diagram illustrating an embodiment in which the switching drive section of the pusher elastically deforms when switching between a friction clutch and a friction brake. Figure 9 This is an explanatory diagram illustrating the connection and non-connection of various levels of one-way clutches, friction brakes, and friction clutches according to embodiments of the present invention. Figure 10 This is a flowchart used to explain the operation of the control circuit when the electric motor does not have an electromagnetic brake. Figure 11 This is a schematic diagram of a control motor with an electromagnetic brake. Figure 12 It is along Figure 11 The sectional view shown by line XII-XII. Figure 13 This is a schematic timing diagram illustrating the re-engagement action of the friction clutch and friction brake, which is achieved by the electromagnetic brake. Figure 13 (A) indicates the action of the electromagnetic brake. Figure 13 (B) indicates the action of the solenoid. Figure 14A It is part of a flowchart used to explain the operation of a control circuit for controlling an electric motor with an electromagnetic brake. Figure 14B yes Figure 13 The remainder of the flowchart follows. Figure 15 It is Figure 2 The two-stage transmission is configured as a cross-sectional view of the actual equipment. Figure 16 yes Figure 15 A schematic detailed diagram of the ball screw mechanism in the image. Figure 17 This is a schematic diagram of the overall framework of a two-stage transmission that switches between the first and second stages via a swing arm. Figure 18 This is a summary front view of the swing arm. Figure 17 (Outline sectional view along line XVIII-XVIII). Figure 19 yes Figure 17 A schematic diagram of the spline engagement between the threaded component and the nut component (along...) Figure 17 (Outline sectional view of the IXX-IXX line). Figure 20 This is a schematic diagram of the overall framework of a two-stage transmission that uses two sets of swing arms to switch between friction clutches for the first and second stages. Detailed Implementation

[0022] [Overall Structure] Figure 1 The diagram schematically illustrates the drive system of the electric vehicle of the present invention. 2 represents the electric motor used for driving, i.e., the drive motor; 4 represents the two-stage transmission of the present invention; 6 represents the reducer; 8 represents the differential gear; and 9 represents the wheel. The two-stage transmission 4 includes an input shaft 10 facing the drive motor 2 and an output shaft 12 facing the reducer 6. The reducer 6 is configured to house meshing gears within a housing. It is designed to reduce the high rotational speed of the drive motor 2 to a speed suitable for driving using the wheels 9. In a typical electric vehicle without the two-stage transmission 4, the reduction ratio of the reducer 6 is set to a value around 3.5. This is to allow the drive motor 2 to operate in an efficient speed range at commonly used low vehicle speeds. However, in this configuration, the motor's rotational speed increases excessively due to high vehicle speeds, resulting in decreased motor efficiency and inability to operate at high speeds. Therefore, the two-stage transmission 4 is provided. In this invention, the transmission 4 includes a planetary gear mechanism. In this embodiment, the first stage is configured to input a sun gear and output a gear carrier for speed reduction (reduction ratio, for example, 1.6), and the second stage is configured to have a direct input-output connection (gear ratio of 1.0). Assuming the reduction ratio of the reducer 6 is 2.2, the total reduction ratio is 1.6 × 2.2 = 3.52, which is approximately the same as the total reduction ratio in the case of a conventional transmission without a two-stage gearbox. Furthermore, when the second stage is in operation, it operates at a total reduction ratio of 2.2 × 1.0 = 2.2. Since the reduction ratio is smaller, the drive motor 2 can operate in a low-speed, efficient rotational region compared to the low-speed region, thus enabling high-speed operation.

[0023] Figure 2 Represented by a framework diagram Figure 1The basic structure of the two-stage transmission 4 and the reducer 6 in the drive system. In this two-stage transmission, the output shaft 12 is cylindrical and is coaxial with the central input shaft 10 (connected to the output shaft 2-1 of the drive motor 2), that is, it shares a common rotation center.

[0024] The two-stage transmission 4 includes a planetary gear mechanism 16 disposed within a housing 14. The planetary gear mechanism 16 comprises three rotating elements: a gear carrier 20, a sun gear 22, and a ring gear 24. The gear carrier 20 is configured to support a plurality of pinions 18 spaced apart circumferentially for free rotation. The sun gear 22 shares a rotation center with the gear carrier 20 and meshes with the pinions 18. The ring gear 24 also shares a rotation center with the gear carrier 20 and meshes with the pinions 18. The sun gear 22 is connected to the input shaft 10, and the gear carrier 20 is connected to the output shaft 12. Furthermore, it includes a multi-plate friction clutch (hereinafter referred to as a friction clutch) 26, a one-way clutch 27, and a multi-plate friction brake (hereinafter referred to as a friction brake) 28 as connecting elements. Furthermore, in the first stage (coasting), the gear ring 24 is connected to the housing 14 via the one-way clutch 27, and the gear carrier 20 on the output shaft 12 side is set to a reduction ratio of 1.6 relative to the sun gear 28 on the input shaft 10 side, as described above. In the second stage, the sun gear 28 is connected to the gear carrier 20 via the friction clutch 26, so that the input shaft 10 and the output shaft 12 rotate as a unit, with a gear ratio of 1.0, increasing speed relative to the first stage. In the first stage, as described above, during driving, the one-way clutch 27 restricts the gear ring 24 relative to the housing 14 for power transmission. However, if the driver releases the accelerator pedal and coasts (decelerates), the restriction relative to the housing 14 implemented by the one-way clutch 27 will disengage. In this case, by engaging the friction brake 28, the restriction of the gear ring 24 relative to the housing 14 can be ensured, allowing direct and shock-free continuation of the first stage coasting operation. This operation of the one-way clutch 27 will be described later.

[0025] Furthermore, the one-way clutch 27 ensures torque transmission during the idling period of the switching operation between the friction clutch 26 and the friction brake 28. That is, in this embodiment, the friction clutch 26 and the friction brake 28 are axially separated and are switched on and off by the forward and backward movement of the pusher 34 (described later). Therefore, during the switching process, both the friction clutch 26 and the friction brake 28 will inevitably experience a momentary disengagement state. However, during the idling period, especially when switching from the first stage to the second stage, the one-way clutch 27 can ensure the torque of the output shaft, which helps to prevent gear shift shock.

[0026] Regarding the planetary gear mechanism 16, it can also be a double pinion type component with different diameters as the pinion. In this case, the gear carrier that supports the pinion on its shaft and the gears (sun gears or gear rings) with different numbers of teeth that mesh with the different diameter portions of the pinion become the three rotating elements of the planetary gear mechanism.

[0027] The multi-plate friction clutch 26 and the multi-plate friction brake 28 are arranged concentrically with and axially spaced apart from the central shaft of the two-stage transmission 4. As is well known, the friction clutch 26 includes: a drive disc 26-1 that rotates integrally with the input shaft 10, i.e., with the sun gear 22 (capable of sliding axially relative to the clutch drum 26-4 that rotates integrally with the sun gear 22); and a driven disc 26-2 that rotates integrally with the wheel carrier 20 (capable of sliding axially relative to the clutch drum 26-4 that rotates integrally with the wheel carrier 20). Figure 15 The inner drum 66 shown slides axially, and a thrust bearing 26-3 is included on the side of the drive disc 26-1 near the friction brake 28. This is also well known, but the friction brake 28 includes: a drive disc 28-1, which is axially movable but non-rotatably connected to the inner circumference of the housing 14 via a spline engagement (capable of sliding axially relative to the housing 14 via a spline engagement); and a driven disc 28-2, which is axially movable but integrally rotated via a spline engagement with the gear ring 24.

[0028] The actual structure of planetary gear mechanism 16, friction clutch 26, and friction brake 28 in the equipment will be discussed later. Figure 15 Please provide an explanation.

[0029] The one-way clutch 27 is not limited, but in this embodiment, it can be maintained by means of the clamping spring 27-3. Figure 3 The type of cam 27-2 shown is held in place by the retaining ring 27-1. The one-way clutch is not limited to this type; for example, it could also be a roller-type one-way clutch. In the first stage of the two-stage transmission 4, the one-way clutch 27 rotates relative to the gear ring 24 during drive operation. Figure 3 The gear ring 24 is restricted relative to the housing 14 by rotating counterclockwise (f). Then, during sliding operation, the gear ring 24 is set to rotate freely relative to the housing 14. Figure 3 (clockwise direction g).

[0030] In the two-stage transmission 4 of this embodiment, in the first stage drive (non-coasting operation), the friction clutch 26 is set to non-engaged, and the gear ring 24 is restricted relative to the housing 14 by the one-way clutch 27. During the transition of the first stage coasting operation with the one-way clutch 27 idling, a connecting torque is immediately generated. The friction brake 28 is formed in a gapless state by the drive disc 28-1 and the driven disc 28-2 (where the connecting torque = 0). The second stage (both coasting operation and non-coasting operation) is carried out by engaging the friction clutch 26 (the one-way clutch 27 causes the gear ring 24 to idle to the housing 14). That is, in the first stage, the drive disc 28-1 and the driven disc 28-2 are set to gapless in the friction brake 28 (the connecting torque of the friction brake 28 only generates coasting operation), and in the second stage, the drive disc 26-1 and the driven disc 26-2 are set to gapless in the friction clutch 26. A connecting torque is generated in both non-coasting and coasting operation. An actuator 30 is provided for the switching action of such friction clutch 26 and friction brake 28.

[0031] The actuator 30 includes: a control motor 32 serving as an electric rotary motor; a pusher (pressing member of the present invention) 34 for selectively engaging a friction brake 28 (provided in the present invention as a first multi-plate friction clutch for the first stage) and a friction clutch 26 (provided in the present invention as a second multi-plate friction clutch for the second stage); a torque-thrust conversion mechanism 36 for converting the rotational torque of the control motor 32 into thrust (axial back-and-forth movement of the pusher 34); and a power transmission mechanism 38 for transmitting the rotation of the control motor 32 to the torque-thrust conversion mechanism 36. The torque-thrust conversion mechanism 36 is composed of a screwed cylindrical screw 40 (the inner diameter member of the present invention) and a cylindrical nut 42 (corresponding to the outer diameter member of the present invention). In this embodiment, the cylindrical nut 42 comprises a central threaded portion 42-1a, a radially extending circular plate-shaped portion 42-1, and an axially extending cylindrical portion 42-2 from the circular plate-shaped portion (radial wall portion) 42-1, forming a double-layered cylindrical body. The cylindrical portion 42-2 can only move axially within the inner circumference of the outer casing 14 (rotation direction is restricted). Therefore, axial movement of the cylindrical nut 42 is possible through the rotation of the cylindrical screw 40. Since the cylindrical nut 42 can only move axially, therefore, as... Figure 5 As shown, the cylindrical portion 42-2 of the cylindrical nut 42 has a spline 42-2a on its outer periphery. The spline 42-2a engages with the spline 14-1 on the inner periphery of the housing 14. Therefore, the cylindrical nut 42 can move axially relative to the housing 14, but is restricted in the rotational direction by the housing 14, thus allowing for axial back-and-forth movement of the cylindrical nut 42 caused by the rotation of the cylindrical screw 40. Furthermore, Figure 4The diagram schematically illustrates the engagement state of the cylindrical screw 40 and the cylindrical nut 42. The external thread 40-1 of the cylindrical screw 40 engages with the internal thread 40-2 of the cylindrical nut 42. The rotation of the cylindrical nut 42 is restricted to axial movement only. Therefore, the rotation of the cylindrical screw 40, achieved by the control motor 32, is converted into axial movement of the cylindrical nut 42 according to the guide angle conversion (torque-thrust conversion). The torque-thrust conversion generates thrust on the cylindrical screw 40, but for the thrust, such as... Figure 6 As shown, thrust bearings 43a and 43b are provided on both sides of the cylindrical screw 40 between the opposing surfaces of the housing. The pusher 34 includes: an annular circular plate portion 34-1, which is integrally formed in an annular shape and is integrally connected to the cylindrical portion 42-2 at its outer peripheral end; and a friction brake drive portion 34-3a and a friction clutch drive portion 34-3b, which are respectively axially opposite to the friction clutch 26 and the friction brake 28 at the inner peripheral end of the annular circular plate portion 34-1. The friction clutch drive portion 34-3b is configured to face the thrust bearing 26-3, which is located on the drive disc side of the friction clutch 26 closest to the friction brake 28. The thrust bearing 26-3 is configured such that the thrust applied relative to the friction clutch drive portion 34-3b of the fixed pusher 34 in the rotational direction will not impair the rotation of the friction clutch 26 (wheel carrier 20). Furthermore, the friction brake drive portion 34-3a is located opposite the side of the drive disc 28-1 of the friction brake 28 closest to the friction clutch 26. In this embodiment, the structure in which the cylindrical portion 42-2 bears the axial sliding in torque-thrust conversion and the pusher 34 is mounted on the cylindrical portion 42-2 is a common configuration for torque-thrust conversion and thrust transmission.

[0032] In the structure of the actuator 30 described above, the forward and reverse rotational motion of the cylindrical screw 40 is converted into axial left-right linear motion of the cylindrical nut 42, which is engaged with the cylindrical screw 40 and prevented from rotating. This linear motion is transmitted to the pusher 34 via the cylindrical portion 42-2 of the cylindrical nut 42. The switching action between the friction clutch 26 and the friction brake 28 is performed through the friction brake drive portion 34-3a and the friction clutch drive portion 34-3b. The switching action will be described in detail later.

[0033] exist Figure 2In this embodiment, the rotary power transmission mechanism 38 of the two-stage transmission 4 consists of a drive spur gear 44 and a driven spur gear 46. The drive spur gear 44 is fixed to the output shaft 32-1 of the control motor 32, and the driven spur gear 46 meshes with the drive spur gear 44 and is coaxially fixed to the cylindrical screw 40 with the transmission center shaft. The forward and backward rotation of the control motor 32 is transmitted to the cylindrical screw 40 via the rotary power transmission mechanism 38. In this embodiment, the control motor 32 does not include an electromagnetic brake, but as will be described later, it can be equipped with one. Since the rotary power transmission mechanism 38 of this embodiment consists of spur gears 44 and 46, the thrust from the driven spur gear 46 to the cylindrical screw 40 of the torque-thrust conversion mechanism 36 is overwhelmingly less than that of the worm gear mechanism in reference 2, thus having the advantage of not placing an additional burden on the thrust bearings 43a and 43b.

[0034] The reducer 6 includes an input shaft 6-1, an output shaft 6-2, a relay gear set (composed of gear 6-3 on the output shaft 12 of the two-stage transmission 4 and gear 6-4 on the input shaft 6-1 meshing with it), and a gear set for speed change (composed of gear 6-5 on the input shaft 6-1 and gear 6-6 on the output shaft 6-2 meshing with it). Through the reducer 6, a total reduction ratio of 2.2 can be obtained between the output shaft 12 of the two-stage transmission 4 and the output shaft 6-2 of the reducer 6. The output shaft 6-2 of the reducer 6 is connected to the differential 8.

[0035] [Clutch and brake switching achieved by actuators] Next, through Figure 6 and Figure 7 The switching operation of the friction clutch 26 and friction brake 28, implemented by the actuator 30, will be explained. The actuator 30 also has... Figure 2 There may be slight differences or variations, but these are merely for illustrative purposes; the essence remains the same. Figure 6 In (A), L M This indicates the midpoint of the pusher 34 between the friction clutch 26 and the friction brake 28 (corresponding to...). Figure 7 (The origin of the coordinate system), the pusher 34 is located between the friction clutch 26 and the friction brake 28. Figure 7 In the diagram, the horizontal axis represents the rotation angle of the control motor 32's rotation shaft 32-1, and the vertical axis represents the stroke of the pusher 34. By controlling the forward rotation of the motor 32, the pusher 34... Figure 6 Middle right, in Figure 7 The stroke value increases towards the positive side, and by controlling the negative rotation of motor 32, the pusher moves to the left. Figure 7 The mid-stroke value increases towards the negative side. Figure 6 The midpoint L of (A) M(equivalent to) Figure 7 At the origin of the coordinate system, the pusher 34 has a clearance of Ccr+St / 2 between its opposite end and the friction clutch 26 (the thrust bearing 26-3 closest to it), and a clearance of Bcr+St / 2 between its opposite end and the friction brake 28. Here, Ccr is the distance L from the midpoint required to prevent traction torque from being generated between the friction clutches 26 when they are idling (to prevent traction between the drive disc 26-1 and the driven disc 26-2). M The clearance value, Bcr, is the distance L from the midpoint required to prevent the friction brake 28 from generating traction torque (not causing traction between the drive disc 28-1 and the driven disc 28-2) when the friction brake 28 is idling. M The clearance value St is the margin used to ensure that neither the friction clutch 26 nor the friction brake 28 generates traction torque.

[0036] In the pusher 34 from Figure 6 The midpoint L of (A) M When the output shaft 32-1 of the motor 32 rotates clockwise and moves to the right by St / 2, the gap with the friction brake 28 becomes Bcr. When moving further to the right by Bcr from this point, as... Figure 6 As shown in (B), the friction brake drive section 34-3a of the pusher 34 reaches the position where it abuts against the approach side drive plate 28-1 of the friction brake 28, and the drive disc 28-1 and driven disc 28-2 of the friction brake 28 are in complete contact (no torque, no gap) without torque. Here, by increasing the forward torque of the control motor 32, the engagement of the friction brake 28 is completed (switching to the first stage). This state is when the pusher 34 moves from the midpoint L M The state of Bcr+St / 2 has been moved to the right. On the opposite side, there is a gap of Ccr+Bcr+St between the friction clutch drive part 34-3b of the pusher 34 and the friction clutch 26 (equivalent to the target stroke amount b of the pusher 34 for switching from the friction brake 28 to the friction clutch 26).

[0037] In order to change speed from the first stage to the second stage, the friction brake 28 needs to be switched from... Figure 6 The engagement state of (B) is switched to the disengaged state, and the friction clutch 26 is engaged. At this time, by controlling the negative rotation of the output shaft 32-1 of the control motor 32, the pusher 34 moves to the left by Bcr+Ccr+St, and the friction clutch drive part 34-3b of the pusher 34 reaches and abuts against the thrust bearing 26-3 on the approach side of the friction clutch 26. By increasing the negative rotation torque of the control motor 32, the engagement of the friction clutch 26 is completed. This state is as follows: Figure 6As shown in (C), at this time, the gap between the friction brake drive part 34-3a of the pusher 34 and the friction brake 28 is also Bcr+Ccr+St (the target stroke a of the pusher 34 for switching from the friction clutch 26 to the friction brake 28).

[0038] [Increased connection force due to elastic deformation during connection] In the Figure 6 During the switching operation of the friction clutch 26 and friction brake 28 performed by the pusher 34 shown, when the friction brake drive part 34-3a and the friction clutch drive part 34-3b engage with the opposing parts of the friction clutch 26 and the friction brake 28, the pusher 34 can be moved in a manner that further deepens the engagement. In this case, Figure 8 The depiction is exaggerated. Relative to the root portion of the cylindrical portion 42-2, the annular plate portion 34-1 deforms as imagined by line 34-1' when the friction brake drive portion 34-3a abuts against the friction brake 28, and as imagined by line 34-1” when the friction clutch drive portion 34-3b abuts against the friction clutch 26. Although these deformations are within the elastic limit, a reliable connection between the friction clutch 26 and the friction brake 28 can be achieved through its elastic force. In this case, if... Figure 6 In case (B), the elastic deformation at the drive center is set as Dcr, and... Figure 6 If the elastic deformation at the drive center in case (C) is set as Dbr, then Figure 6 (B) Figure 6 The target stroke amounts a and b of the friction clutch 26 and friction brake 28 in (C) are as follows. a = Bcr + Ccr + St + Dcr b = Bcr + Ccr + St + Dbr

[0039] [The shifting action of a two-stage transmission] Next, the gear shifting operation of the two-stage transmission 4 in this embodiment will be explained. The gear shifting operation is as follows: Figure 9 As shown in the diagram, 〇 indicates engagement and × indicates disengagement. The two-stage transmission 4 of this transmission achieves the gear ratios and reverse rotation of the first and second stages described above. Furthermore, the vehicle's state can be broadly categorized into a driving state (driving), where the drive motor outputs positive torque to accelerate the vehicle, and a decelerating state (coasting), where the drive motor regenerates and outputs negative torque to decelerate the vehicle. The following explains the operation when the gear stages are combined with the driving and coasting states.

[0040] First-level drive During the first stage of drive, the pusher 34 is in Figure 6In the right-hand position (B), the pusher 34 has no backlash relative to the friction brake 28 and is disengaged relative to the friction clutch 26, with the largest backlash. The pusher 34 has no backlash relative to the friction brake 28, but the control motor 32 operates without generating connecting torque as described later. Figure 10 The control is performed using a flowchart, and the friction brake 28 is not connected. The component with an electromagnetic clutch, described later, is used as the control motor 32. Figure 13 and Figure 14B In the case of operation, during the first stage of drive, the friction clutch 26 remains engaged via the electromagnetic clutch. Therefore, while the electromagnetic clutch is engaged, the friction brake 28 is engaged. However, due to the re-engagement action of the electromagnetic clutch, the friction brake 28 performs a non-engagement action during the re-engagement period. The one-way clutch 27, which is engaged, performs an engagement action to ensure power transmission during the re-engagement period.

[0041] During the first stage of drive (when the drive motor torque is positive), the input rotational torque is... Figure 2 The input from the drive motor 2 enters the input shaft 10, causing the sun gear 22 to rotate. The ring gear 24 is stopped by the one-way clutch 27 applying a rotation limit. Figure 9 (The engagement of the one-way clutch 27 is indicated by 〇). That is, the one-way clutch 27 engages in... Figure 3 This prevents the cam 27-2 from rotating counterclockwise relative to the gear ring 24. As a result, in Figure 2 In this system, the sun gear 22 enables the wheel carrier 20 to rotate and transmits torque and rotation to the output shaft 12. The output shaft 12 transmits driving force to the wheels 9 via the reducer 6 and the differential 8, thus accelerating the vehicle. As is well known, the gear ratio of the first stage is Zs / (Zs+Zr) (reduction) when the number of teeth of the sun gear 22 is Zs and the number of teeth of the ring gear 24 is Zr.

[0042] During the first stage of deceleration (coasting) During the first stage of deceleration (coasting), the pusher 34 is in a position Figure 6 The right-hand position of (B) (the state where the pusher 34 abuts against the friction brake 28), and the torque control of the motor 32 is performed as described later to produce appropriate coupling torque, rather than the torqueless state as in the first stage drive. Therefore, the friction brake 28 is for coupling ( Figure 9 (〇).

[0043] Conversely, during the drive phase, the input rotational torque during the first stage of reduction enters the wheel carrier 20 from the output shaft 12, and the pinion 18 applies torque in the direction that causes the sun gear 22 and the ring gear 24 to rotate. Because the ring gear 24 rotates in the freewheeling direction of the one-way clutch 27 (in... Figure 3Due to the clockwise rotation (the cam 27-2 is inactive), the input torque is used to prevent the gear ring 24 from spinning freely by connecting the friction brake 28. Thus, the rotation from the wheel 9 can be directly transmitted to the drive motor 2, which generates negative torque through electrical regeneration, thereby transmitting negative torque to the wheel 9 to decelerate the vehicle.

[0044] Second-level drive During the second stage of drive, the pusher 34 is in Figure 6 The friction clutch 26 is engaged (c) at the left-hand position, and appropriate torque is applied from the control motor 32. Figure 9 (0), friction brake 28 is not engaged. During the second-stage drive, the input rotation / torque enters the input shaft 10 from the drive motor 2, causing the clutch drum, which is connected to the sun gear shaft, to rotate. The clutch drum rotates to the wheel carrier 20 via the engaged friction clutch 26, in the same manner as the drive motor 2. Since the wheel carrier shaft is also integrated with the wheel carrier 20, the output shaft 12 rotates from the wheel carrier 20 with the same rotation as the drive motor 2 (gear ratio 1.0, relative speed increase relative to the first stage). At this time, torque in the idling direction of the one-way clutch 27 is applied to the gear ring 24, and since the friction brake 28 is not engaged, it rotates with the same rotation as the drive motor 2.

[0045] Second-stage deceleration (coasting) Friction clutch 26 is for connection (refer to) Figure 9 Friction brake 28 is non-connected, the same as in the second stage drive.

[0046] During the second stage of deceleration, the input rotation / torque flows in the opposite direction to that during driving. The output shaft 12 enters the wheel carrier 20 and the wheel carrier shaft, and through the connected friction clutch 26, it rotates from the sun gear shaft to the drive motor 2 with the same rotation. Thus, during the second stage of non-driving, the negative torque generated by the electric regeneration of the drive motor is transmitted to the wheels 9, causing the vehicle to decelerate appropriately.

[0047] When reversed The input rotation / torque during reversal is transmitted to the sun gear 22 by reversing the drive motor 2, and then applied to the gear ring 24 in the direction of reversal via the gear carrier 20. Since the gear ring 24 receives torque in the idling direction of the one-way clutch 27, the torque is transmitted through the friction brake 28 (…). Figure 9 This prevents the gear ring 24 from spinning freely. Thus, the reverse torque and rotation of the drive motor are transmitted to the wheel 9.

[0048] [Actuator control (without electromagnetic brake)] Next, regarding the switching action between level one and level two, through... Figure 10 The flowchart below illustrates the control logic of the motor 32 in actuator 30. The description of the reverse operation is omitted from the flowchart. Figure 2 In the diagram, 47 represents the transmission control circuit for controlling the electric motor 32, which is operated by a microcomputer. The control circuit 47 receives inputs from the throttle opening and vehicle speed, signals from the position sensor of the rotating shaft 32-1 controlling the electric motor 32, and signals from other sensors. The electric motor 32 is controlled by internally stored software. Furthermore, in the following description, the calculation of the position of the pusher 34 relative to the friction brake 28 and the friction clutch 26, i.e., the necessary stroke of the pusher 34, is not specifically described. However, it can be determined using known methods through the detection values ​​of the position sensor located on the rotating shaft 32-1 controlling the electric motor 32.

[0049] exist Figure 10 In this context, step 100 represents the input of throttle opening and vehicle speed signals used to determine the vehicle's operating status. In step 102, the throttle opening and vehicle speed signal information are used to determine whether the shift is not a gear change. If the shift is determined, the process proceeds to step 104 to determine whether the shift is from the first gear to the second gear. If the shift is confirmed to be from the first gear to the second gear, the pusher 34 initially... Figure 6 As shown in (B), the device is in contact with the friction brake 28 (first stage), with a clearance of b = Ccr + Bcr + St relative to the friction clutch 26. This becomes the target stroke of the pusher 34. To transition to the second stage from this point, before reaching engagement of the friction clutch 26 by controlling the negative rotation of the control motor 32, the pusher 34 needs to be moved from... Figure 6 Move the (B) position to the left until there is no clearance with the friction clutch 26, thus obtaining the target stroke amount. In the next step 106, before determining in step 108 that the deviation δb relative to the target stroke amount b is 0, i.e., before... Figure 6 Before the pusher 34 shown in (C) reaches the state of contact with the friction clutch 26, the current value of the control motor for the movement of the pusher 34 is continuously output to the control motor 32 (although it is the negative rotation of the control motor 32, as a torque value, it is a value that can make the pusher 34 move as little as possible without causing the friction clutch 26 to generate a connecting force). If it is determined in step 108 that δb = 0, then proceed to step 110, calculate the connecting force (torque of the control motor 32) required for the friction clutch 26 to engage in this operating state, convert it into the required current value in step 112, and output a current indication from the control circuit 47 to the control motor 32 in step 114.

[0050] Thus, when completing the speed change from level one to level two, in the next... Figure 10During routine execution, steps 100 and 102 are entered. When a positive judgment is made in step 102, step 116 is entered. Since the current level is the second level, a negative judgment is made in step 116, thus entering step 110. Under the operating state determined by the throttle opening or vehicle speed input in step 100, the torque required for the control motor 32 to maintain the engagement of the friction clutch 26 is calculated. The required current value is calculated in step 112. In step 114, the operation instruction of the control motor 32 is given (output of the required current value calculated in step 112).

[0051] When shifting from the second stage of operation to the first stage, the process proceeds from steps 100 and 102 to step 104. Due to a negative judgment, it proceeds to step 119. At this point, if... Figure 6 As shown in (C), the pusher 34 is in a state with no clearance relative to the friction clutch 26. To transition to the first stage from this point, before engaging the friction brake 28, the pusher 34 needs to be moved to the right by a target stroke amount a = Ccr + Bcr + St in the diagram, before the deviation δa = 0 relative to the target stroke amount a is determined in step 120, i.e., as shown in (C). Figure 6 Before the pusher 34 shown in (B) reaches a state with no clearance relative to the friction clutch 28, a current value for the control motor used to move the pusher 34 is continuously output to the control motor 32 (although it is the forward rotation of the control motor 32, the torque value is one that minimizes the contact force on the pusher 34 and does not cause the friction clutch 26 to generate a connecting force). If it is determined in step 120 that δa = 0, that is, the pusher 34 has reached a state with no clearance relative to the friction brake 28, step 122 is entered, and the torque of the control motor 32 is set to zero. The current value is also zero (step 112), and step 114 is entered, indicating the intended action. That is, in the first-stage drive state, power transmission is participated in by the one-way clutch 27, and the friction brake 28 does not participate in power transmission; therefore, the torque is zero.

[0052] Thus, when the speed change from the second stage to the first stage is completed (reaching a state where there is no gap between the pusher 34 and the friction brake 28), in the next routine, after steps 100 and 102, proceeding through step 116, to step 118, where it is determined whether it is in a coasting state (coasting state in the first stage). If it is not a coasting state even in the first stage, a negative judgment is made in step 118, and therefore, proceeding to step 122, the torque of the friction brake 28 remains zero.

[0053] If the driver releases the accelerator pedal in the first stage and enters a coasting state, steps 100, 102, and 116 are followed, and a positive judgment is made in step 118. Then, step 124 is initiated. Based on the throttle opening and vehicle speed, the required torque for the friction brake 28 to prevent slippage is calculated according to the torque of the drive motor 32 corresponding to the operating state in the first stage of coasting. In step 112, the current value of the control motor 32 corresponding to this friction torque is calculated, and in step 114, this current value is output from the control circuit 47 to the control motor 32. In the coasting state, the one-way clutch 27 idles, but because an appropriate friction torque is immediately applied from the control motor 32 to the friction brake 28, which has reached a zero-gap position relative to the friction brake 28, a smooth transition to coasting operation can be achieved without deceleration shock.

[0054] [Actuator control (with electromagnetic brake)] In the implementation of this invention, as Figure 2 The control motor 32 can be a control motor equipped with an electromagnetic brake. By equipping the control motor 32 with an electromagnetic brake, the friction brake 28 and friction clutch 26 can be engaged and maintained without torque drive provided by the control motor 32, thereby reducing the power consumption of the control motor 32. Figure 11 As schematically shown, the electromagnetic brake 48 is disposed on the output shaft 32-1 and includes an annular drive plate 50 formed of a weakly magnetic material, an annular brake shoe 52, multiple springs 54 arranged circumferentially, and a solenoid (electromagnetic coil) 56. The mounting portion of the output shaft 32-1 on the drive plate 50 includes an outer peripheral spline 32-1A. Figure 12 The spline 32-1a engages with the spline hole 50-1 of the drive plate 50, allowing the drive plate 50 to slide axially relative to the output shaft 32-1, but maintaining a fixed relationship in the rotational direction. The connection state of the electromagnetic brake 48 is achieved by de-energizing (disconnecting) the solenoid 56 (see reference). Figure 13 At this time, under the action of the spring 54, the drive plate 50 locks the brake shoe 52 to the locking part 58 on the side of the motor housing, and the output shaft 32-1 of the control motor 32 is restricted to stop.

[0055] The non-connected state of the electromagnetic brake 48 is obtained by energizing (connecting) the solenoid 56 (see reference). Figure 13At this point, due to electromagnetic force, the drive plate 50 resists the spring 54 and shifts axially towards the solenoid 56 side. The restriction on the output shaft 32-1 of the control motor 32, implemented by the brake shoe 52, is released, allowing the rotation of the output shaft 32-1 of the control motor 32 to be transmitted to the actuator 30 side. The output shaft 32-1 of the control motor 32 rotates continuously, but the large torque is only generated when the friction clutch 26 and the friction brake 28 are engaged. Otherwise, the control motor 32 can operate with the minimum torque required to perform the stroke movement of the pusher 34, thereby reducing the overall power consumption.

[0056] pass Figure 13 and Figure 14B The flowchart below explains the switching operation between the first and second stages when the control motor 32 is configured to include the electromagnetic brake 48. The main part of this operation involves maintaining the connection between the friction clutch 26 and the friction brake 28 via the electromagnetic brake 48, independent of the rotational torque of the control motor 32. In the following flowchart explanation, for... Figure 10 For the same processing steps, use the same marker (replace 100), omit repetitive explanations as much as possible, and simplify as much as possible. Figure 10 The processing not described in the text is replaced by the notation 200 and explained in detail. After inputting the throttle opening signal and vehicle speed signal in step 100, in the case of shifting from the first stage to the second stage, in step 200, the solenoid 56 of the electromagnetic brake 48 ( Figure 11 Power on and set the electromagnetic brake 48 to non-connected (refer to...) Figure 13 This allows the rotation of the control motor 32's rotating shaft 32-1 to be transmitted to the actuator 30, and proceeds to steps 104, 106, and 108, so that the pusher 34 can move from... Figure 6 (b) The position where it abuts against the friction brake 28 moves to the left and gives a negative rotation indication to the control motor 32, if the pusher 34 abuts against the friction clutch 26 (thrust bearing 26-3). Figure 6 When the state of (C) is reached, i.e., when the target stroke b of the pusher 34 used for the first-stage speed change is completed, a positive judgment (δb = 0) is made in step 108, and the above-mentioned steps 110, 112, and 114 are performed to calculate the necessary torque of the control motor 32, so that the friction clutch 26 can be engaged with the necessary torque.

[0057] Thus, if the torque required to maintain engagement is obtained in the friction clutch 26 and the shift to the second gear is completed, then in the immediately following routine, from step 100 through step 102, proceeding to step 202, a determination is made as to whether the electromagnetic brake 48 is engaged. Since the electromagnetic brake 48 was initially set to disengaged (the solenoid 56 was energized (connected) in step 200), therefore, proceeding to step 204, the electromagnetic brake 48 is engaged (i.e., Figure 11 The solenoid 56 is demagnetized (disconnected). The connection of the electromagnetic brake 48 restricts the rotation of the motor shaft 32-1, enabling it to maintain a certain position without relying on the rotational torque of the control motor 32. Figure 6 The engagement state of the friction clutch 26 shown in (C) is as follows. In the next step 206, it is determined whether the current stage is the first stage. Since the current stage is the second stage, a negative judgment is made and the process proceeds to step 208. In step 208, it is determined whether the gear ratio of the second stage is normal. That is, if the engagement torque of the friction clutch 26 caused by the engagement of the electromagnetic brake 48 is normal, then in Figure 6 In step (C), the pusher 34 is kept in contact with the friction clutch 26. If the engagement torque decreases, the contact state is disengaged, and the pusher 34 shifts towards the friction brake 28. Therefore, an abnormality can be determined based on the detection position of the rotation shaft 32-1 of the control motor 32. If the gear ratio of the second stage is not abnormal, step 210 is entered, and a predetermined time Tsec is determined from the engagement of the last electromagnetic brake 48. If the predetermined time Tsec has not elapsed, the cycle returns to step 208, maintaining the engagement state of the friction clutch 26 achieved by the electromagnetic brake 48. If it is determined in step 208 that a predetermined time Tsec has elapsed from the engagement of the last electromagnetic brake 48, or if it is determined in step 208 that the gear ratio of the second stage is abnormal, step 212 is entered, and the electromagnetic brake 48 is temporarily set to non-engaged (solenoid 56 is energized (connected)). In step 214, a torque value is sent to the control motor 32 in the negative rotation direction (in Figure 6 The working indication (MAX) in (C) reduces the gap between the pusher 34 and the friction clutch 26 to the left (in the leftward direction). In the next step 215, even if one end of the friction clutch 26 is disengaged, a standby time τsec is performed for the time required to restore it to the engaged state. Figure 13 The re-engagement action of the friction clutch 26 in the second stage is schematically shown. Every Tsec, the electromagnetic brake 48 is decoupled, resulting in a negative rotation (duration τ) at the maximum torque of the control motor. Furthermore, even if Tsec has not been reached, as long as an abnormal secondary gear ratio is determined in step 208, the friction clutch 26 can be re-engaged immediately.

[0058] When shifting speed from the second stage to the first stage, after step 100 and step 102, by setting the electromagnetic brake 48 to disengagement in step 200, the rotation of the control motor 32 can be transmitted to the actuator 30. Then, steps 104, 118, and 120 are performed, causing the operation indication of the control motor 32 to shift from its current position (as the pusher 34) to contact with the friction clutch 26. Figure 6 The state of (C) moves to the right towards the friction brake 28 (control motor 32 rotates forward), completing the movement of the target value a of the pusher 34 for the first speed change, with a deviation δa = 0. When the friction brake 28 is in the connected state, in step 122, the torque value of the friction brake 28 is set to zero, and steps 112 and 114 are entered. The indication is that the indicator current = 0, the pusher 34 and the friction brake 28 are without gap, but the torque applied to the friction brake 28 is zero.

[0059] Thus, during the transition to the first gear, after step 100 and step 102, and through the processes described in steps 202 and 204, the electromagnetic brake 48 is engaged (the solenoid 56 is de-energized (disconnected)), the friction brake 28 becomes gapless relative to the pusher 34, and the torque applied to the friction brake 28 is maintained at 0. In the next step 206, since the current gear is the first gear, a positive judgment is made, and the process proceeds to step 216 to determine if there is an abnormality in the gear ratio of the first gear. That is, if the gear ratio of the first gear is normal, then if the position of the pusher 34 relative to the friction brake 28, achieved by the electromagnetic brake 48, is normal, it is in a contact state. If the pusher 34 deviates from the contact state with the friction brake 28 and its position shifts towards the friction clutch 26, then based on the detection value of the rotation shaft 32-1 of the control motor 32, it can be determined that the gear ratio of the first gear is abnormal. If the gear ratio of the first stage is normal, proceed to step 218 to determine whether a predetermined time Tsec has elapsed since the last electromagnetic brake 48 was connected. If the predetermined time Tsec has not elapsed, return to step 216. If it is determined in step 218 that a predetermined time Tsec has elapsed since the last electromagnetic brake 48 was connected, or if it is determined in step 216 that the gear ratio of the first stage is abnormal, proceed to step 220 to decouple the electromagnetic brake 48 (energize the solenoid 56) and release the restriction on the electromagnetic brake 48 by the rotation shaft 32-1 of the control motor 32. In step 222, the control motor 32 is set to rotate in the forward direction (…). Figure 6The current value set to the maximum value (MAX) in the rightward direction (in the direction of reducing the gap between the pusher 34 and the friction brake 28) is calculated, and this current value is indicated to the control motor 32 until the specified time τsec in step 215 has elapsed. The re-gripping action of the friction brake 28 is also related to... Figure 13 Similarly, every Tsec, the electromagnetic brake 48 is decoupled, resulting in forward rotation (duration τ) at the maximum torque of the control motor. Furthermore, even if Tsec has not been reached, if an abnormality is determined in step 216, the friction brake 28 in the first stage of coasting operation is immediately re-engaged.

[0060] In the above Figure 13 and Figure 14B In the control, in the first stage, regardless of the driving state or coasting state in the first stage, the holding friction brake 28 is connected via the electromagnetic brake 48, such as... Figure 10 As in the implementation method, during the transition to a coasting state, control of the friction brake engagement cannot be accessed. Therefore, control is simplified and power is saved, and the driver can feel the deceleration, thereby improving operability. That is, in this control, the friction brake 28 is engaged and held independently of driving and coasting in the first stage, but during re-engagement ( Figure 13 During the non-engaged period of friction brake 28, the one-way clutch 27 engages in a manner that ensures power transmission.

[0061] In the above Figures 14A-14B The flowchart illustrates the operation of the control motor 32, including the electromagnetic brake 48. By utilizing the electromagnetic brake 48 to maintain the engagement of the friction brake 28 during the first stage of sliding and the engagement of the friction clutch 26 during the second stage, energy saving is achieved because the rotational torque of the control motor 32 is minimal during this period, and the solenoid 56 of the electromagnetic brake 48 is not energized. Furthermore, for the re-engaging action of the friction clutch 26 and the friction brake 28, the solenoid 56 of the electromagnetic brake 48 is energized (connected) and the control motor 32 operates at maximum torque only for a brief moment (τ) when the electromagnetic brake 48 is not engaged (refer to...). Figure 13 Therefore, it will not substantially impair the overall power saving and can ensure the reliability of the connection between the friction clutch 26 and the friction brake 28 realized by the electromagnetic brake 48.

[0062] In the implementation of this invention, as described above, the electromagnetic brake 48 is as follows: Figures 14A-14BAs shown in the flowchart, when the electromagnetic brake 48 is not engaged (when the torque of the control motor 32 is transmitted to the actuator 30), the solenoid 56 is energized; when the electromagnetic brake 48 is engaged (when the engagement torque is maintained), the solenoid 56 is de-energized. Figure 11 From the perspective of saving power consumption, the structure is preferred. However, as an electromagnetic brake, it is possible to adopt the following type, depending on the situation: it can be set to be unconnected when the solenoid is not energized, and connected by energizing the solenoid.

[0063] [Actual Equipment Structure of a Two-Stage Transmission] Figure 15 It shows that Figure 2 The two-stage transmission, as an example of the structure of actual equipment, has components with the same function labeled as... Figure 2 The same reference numerals are used. The central axis of the input shaft 10 is indicated by 10a, and it is supported at both ends by angular contact ball bearings 62 and 64 on the vertical wall portion 14-3 of the housing 14. The cylindrical output shaft 12 is coaxially supported with the input shaft 10 by angular contact ball bearings 65, etc. The planetary gear mechanism 16 includes a carrier 20 and a sun gear 22. The carrier 20 meshes with the sun gear 22 on the inner side, and is supported on the outer side by a pinion pin 67 for a pinion 18 that meshes with the gear ring 24. The sun gear 22 engages with the input shaft 10 on its inner circumference via a spline 10-1, and rotates integrally with the input shaft 10.

[0064] The friction clutch 26 consists of an inner wheel drum 66, a driven plate 26-2, an outer wheel drum 26-4 (fixed to the sun gear 22), a drive plate 26-1 (which together with the driven plate 26-2 constitutes a clutch assembly), and a thrust bearing 26-3. The inner wheel drum 66 rotates integrally with the wheel frame 20 along with the pinion pin 67. The driven plate 26-2 is splinedly engaged with the spline 66-1 of the inner wheel drum 66. The outer wheel drum 26-4 rotates integrally with the sun gear 22. The drive plate 26-1 is splinedly engaged with the inner circumferential spline 67 of the outer wheel drum 26-4 and alternately arranged with the driven plate 26-2. The thrust bearing 26-3 is located on the side of the clutch assembly furthest from the outer wheel drum 68.

[0065] The friction brake 28 consists of a driven plate 28-2, an outer wheel drum portion 14-2, and a drive plate 28-1 (which, together with the driven plate 28-2, forms a clutch assembly). The driven plate 28-2 engages with the splined outer periphery 24-1 of the gear ring 24, which also serves as the inner wheel drum. The outer wheel drum portion 14-2 is part of the outer casing. Figure 2 The drive plate 28-1 is integrally connected to the outer casing 14); the drive plate 28-1 is splined with the inner peripheral spline 14-2a of the outer wheel drum 14-2, and is alternately arranged with the driven plate 28-2 along the axial direction.

[0066] One-way clutch 69 is disposed on the inner circumference of gear ring 24 and formed in housing 14 of friction brake 28. Figure 2 The integral part of the outer drum 14-2 is between the inner circumference of the annular protrusion 14-3 and the outer circumference of the outer drum 14-2. Due to Figure 3 The one-way clutch 27 shown has its configuration reversed at the inner and outer circumferences. Therefore, the locking and idling directions of the one-way clutch 69 are opposite to those of the one-way clutch 27, but the operation itself is the same.

[0067] The actuator 30 for switching between the friction clutch 26 and the friction brake 28 includes a control motor 32, a pusher 34, a torque-thrust conversion mechanism 36, and a rotary power transmission mechanism 38. The rotary power transmission mechanism 38 is composed of a drive-side spur gear 44 and a driven-side spur gear 46. The torque-thrust conversion mechanism 36 includes a cylindrical screw 40 (inner diameter member); and a cylindrical nut 42A that engages with the cylindrical screw 40 (in this embodiment, the cylindrical nut 42A is only the engagement portion that engages with the cylindrical screw 40, and functions as the outer diameter member of the present invention by being integrated into the double-layered cylindrical body described below), and the cylindrical nut 42A is integrally connected to form a double-layered cylindrical body by including a circular plate portion 42A-1 for limiting rotation and a cylindrical portion 42A-2 that can slide relative to the housing 14. To integrate with the cylindrical nut 42A, the circular plate portion 42A-1 engages with the outer spline of the cylindrical nut 42A in the inner circumferential spline hole of the lower flange portion 42A-1a, and is fixed to the cylindrical nut 42A by a retaining ring 80, thereby integrating the cylindrical nut 42A into a double-layered cylindrical body. In this actual device structure, the screwing of the cylindrical screw 40 and the cylindrical nut 42A forms a known ball nut mechanism via balls 72 arranged in an infinitely circulating path between them. Figure 15 This is a simplified diagram, but for reference only. Figure 16 (Detailed drawing). The cylindrical screw 40 is rotatably supported on the input shaft 10 by the bushing 74. To withstand thrust, thrust bearings 43a and 43b are arranged on both sides of the cylindrical screw 40. The pusher 34 is a ring-shaped stamped product formed from sheet metal. The outer cylindrical portion 34-2 can move axially by spline engagement with the cylindrical portion 42-2 of the cylindrical nut 42, but is restricted in the rotational direction by a retaining ring 82. The pusher 34 is integrally connected to the cylindrical nut 42A. By rotating the cylindrical screw 40, the cylindrical nut 42A can push the pusher 34 axially (thrust transmission). Moreover, the radially central portion of the pusher 34 is formed as an annular protrusion opposite to the friction clutch 26 via the thrust bearing 26-3. This annular protrusion serves as the friction clutch drive portion 34-3b (see reference). Figure 6The friction clutch 26 and the friction brake 28 are switched by means of the radial inner end of the push member 34 extending axially toward the friction brake 28.

[0068] exist Figure 15 In this structure, since the input shaft 10 is supported on the housing by angular contact bearings 62 and 64 at both ends, the core of the input shaft 10 can be easily and reliably achieved with sufficient accuracy. The rolling support of the inner circumferential cylindrical screw 40 of the torque-thrust conversion mechanism 36 relative to the input shaft 10 can be reliably achieved by a simple mechanism such as the bushing 74. Furthermore, the axial left-right movement limitation of the outer circumferential cylindrical nut 42A can also be achieved with sufficient thrust resistance through a simple support structure such as thrust bearings 43a and 43b. Therefore, without incurring excessive costs, the long-term stable operation of the torque-thrust conversion mechanism 36 for switching the connection between the friction clutch 26 and the friction brake 28 can be ensured while suppressing the shaft size of the torque-thrust conversion mechanism 36.

[0069] For example, details of a ball nut mechanism Figure 16 As shown, the ball bearing 72 is tightly configured between the external thread 40a of the cylindrical screw 40 forming an infinite loop track and the internal thread 42A-a of the cylindrical nut 42A. A loop path 84 is formed on the cylindrical nut 42, located in an approximately 180-degree angular region of the cylindrical nut 42A. The loop path 84 opens tangentially into the thread that houses the ball bearing 72. This opening serves as either a ball discharge portion or a ball inlet portion depending on the direction of rotation, thus forming an infinite loop track for the ball bearing 72. The above-described ball bearing nut mechanism is an example; suitable structures available to the market can be employed. [Implementation method including a swing arm actuator for two-stage transmission]

[0070] Figures 17-19This diagram illustrates a spur gear-type two-stage transmission mechanism 300 used to replace the planetary gear mechanism for two-stage gear shifting, with clutch switching via a swing arm actuator. Reference numerals are retained for components with the same structure and function. The spur gear-type two-stage transmission mechanism 300 performs the following function: transmitting the rotation of the drive motor 2 (which functions as an electric motor) to the wheels 9 via the reducer 6 and differential gear 8 at a gear ratio corresponding to the vehicle speed. The spur gear-type two-stage transmission mechanism 300 includes a primary gear set 301 and a secondary gear set 302. The primary gear set 301 consists of a meshing pair of input-side spur gears 301-1 and output-side spur gears 302-2, and the secondary gear set 302 consists of a meshing pair of input-side spur gears 302-1 and output-side spur gears 302-2. Figure 2 The same applies when describing the implementation method. The gear ratio of the input-side spur gear 301-1 and the output-side spur gear 302-2 in the first-stage gear set 301, including the gear ratio of the reducer 6, is set to drive the wheel 9 by driving the motor 2 through the expected gear ratio in the first-stage operation (low vehicle speed). Alternatively, the gear ratio of the input-side spur gear 302-1 and the output-side spur gear 302-2 in the second-stage gear set 302 is set to drive the wheel 9 by driving the motor 2 through the expected gear ratio in the second-stage operation (high vehicle speed).

[0071] Furthermore, the spur gear type two-stage transmission mechanism 300 includes: a primary gear friction clutch 304 as a multi-plate friction clutch; and a secondary gear friction clutch 306 as a multi-plate friction clutch, the secondary gear friction clutch 306 being configured to be slightly separated from the primary gear friction clutch 304 on the transmission input shaft 10, which is coaxial with the rotation shaft 2-1 of the rotary drive motor 2. The primary gear friction clutch 304 includes a drive-side clutch plate 304-1 and a driven-side clutch plate 304-2, the drive-side clutch plate 304-1 being fixed to the output shaft 2-1 of the primary gear clutch 304 for rotational connection, and the driven-side clutch plate 304-2 being fixed to the input-side spur gear 301-1 of the primary gear set 301 for rotational connection. The friction clutch 306 for the secondary gear includes a drive-side clutch plate 306-1 and a driven-side clutch plate 306-2. The drive-side clutch plate 306-1 is fixed to the transmission input shaft 10 for rotational connection, and the driven-side clutch plate 306-2 is fixed to the input-side spur gear 302-1 of the secondary gear set 302 for rotational connection.

[0072] Actuator 308 is provided for switching between the primary gear friction clutch 304 and the secondary gear friction clutch 306. Actuator 308 includes a control motor 32, which is an electric rotary motor. Figure 18 On this point with Figure 1-16 The implementation method is the same. In this embodiment, the actuator 308 includes a torque-thrust conversion mechanism 310 that converts the rotational torque of the control motor 32 into thrust, and is functionally the same as... Figures 1 to 16 The torque-thrust conversion mechanism 36 is common to all other torque-thrust conversion mechanisms, but it is composed of a threaded member 312 (the inner diameter member of the present invention) on the inner diameter side and a nut member 314 (the outer diameter member of the present invention) on the outer diameter side. Furthermore, the actuator 308 also includes: a swing arm 316 (the thrust transmission member of the present invention) for transmitting thrust; an annular pusher 318 (the pressing member of the present invention) for switching the engagement of the friction clutch 304 for the first-stage gear and the friction clutch 306 for the second-stage gear; and a control motor 320 for transmitting the rotation of the control motor 32 to the torque-thrust conversion mechanism 310.

[0073] like Figure 18 As shown, the swing arm 316 is formed by an annular body portion 316-1, a tongue portion 316-2 at the upper end of the annular body portion 316-1, and a pair of ears 316-3. The annular body portion 316-1 is coaxial with the transmission input shaft 10 in a neutral state. The pair of ears 316-3 extend downwards from the annular body portion 316-1, parallel to the upper tongue portion 316-2, at a position opposite in diameter to the upper tongue portion 316-2. The upper tongue portion 316-2 of the swing arm 316 is pivotally connected to the housing 14 (arm pivot connection portion 14-4) via an arm support pin 322. The swing arm 316 is configured to be able to rotate around the transmission central axis (with...). Figure 17 (parallel to the paper surface) and the central axis of the arm support pin 322, that is, the rotation center orthogonal to the central axis of the transmission (and) Figure 17 (The paper surface is orthogonal) oscillates. For example... Figure 17 As shown, a pair of pusher support pins 324 are arranged in diametrically opposed positions. The inner end of each pusher support pin 324 is inserted into the pusher 318 from its outer peripheral surface, and the outer end is inserted into the annular main body 316-1 of the swing arm 316. Thus, the pusher 318 is supported relative to the swing arm 316 at a certain angle around a centerline orthogonal to the central axis of the transmission. With this support structure of the swing arm 316, the switching operation between the primary gear friction clutch 304 and the secondary gear friction clutch 306, implemented by the pusher 318, can be performed. That is, by moving the swing arm 316 from... Figure 17The swing arm 316, in its upright position, rotates clockwise around the arm support pin 322, driving the pusher 318 toward the primary gear friction clutch 304. The primary gear friction clutch 304 is engaged via the thrust bearing 326. Conversely, by rotating the swing arm 316 counterclockwise around the arm support pin 322, the pusher 318 is driven toward the secondary gear friction clutch 306, which is engaged via the thrust bearing 328. In this switching action between the primary gear friction clutch 304 and the secondary gear friction clutch 306, the pusher 310 initially tilts slightly due to its rotational structure around the pusher support pin 320. However, through the rotational support structure of the pusher 310 relative to the arm 316, implemented by the pusher support pin 324, the posture of the pusher 310 relative to the swing arm 316 is ultimately corrected, allowing it to engage with the opposing clutch face in an upright position.

[0074] The threaded member 312 on the inner diameter side and the nut member 314 on the outer diameter side of the torque-thrust conversion mechanism 310 are located on the opposite side of the pivot point of the swing arm 316 relative to the housing, such that they clamp the friction clutch 304 for the first-stage gear and the friction clutch 306 for the second-stage gear. In this embodiment, the threaded member 314 is a solid rod-shaped member that extends parallel to the central axis of the clutches 304 and 306, and is rotatably supported on the housing at both ends by bearings 330. The threaded member 312 and the nut member 314 can also be configured to... Figure 16 The same ball screw. For example... Figure 19 As shown, the nut component 314 engages with the spline hole 14-5a in the nut mounting portion 14-5 of the housing via the spline 314-1 on its outer periphery, preventing rotation while simultaneously converting the rotation of the threaded component 312 into axial linear movement of the nut component 314. To obtain the swinging motion of the swing arm 316 through the linear motion of the nut component 314, as... Figure 17 and Figure 18 As shown, the drive pin 332 is fixed at the opposite diameter position of the middle part of the cylindrical nut component 314 in the long side direction. On the other hand, a pin hole 334 extending elongatedly along the long side direction of the arm 316 is formed in the ear 316-3 of the swing arm 316. The free end of the drive pin 332 is fitted into the pin hole 334 from the nut component 314. Figure 17 and Figure 18 At the neutral position of the swing arm 316 shown, the pin hole 328 has a vertical clearance relative to the drive pin 332. This clearance is accompanied by the axial linear movement of the screw member 312 caused by the rotation of the center screw 314, which pulls the swing arm 316 to rotate, thereby realizing the switching action of the friction clutch 304 for the first-stage gear and the friction clutch 306 for the second-stage gear caused by the forward and backward movement of the push member 318.

[0075] In this embodiment, such as Figure 18 As shown, the power transmission mechanism 320 for transmitting the rotation of the control motor 32 to the center screw 314 consists of a worm gear 340 connected to the rotation shaft of the control motor 32 and a worm wheel 342 fixed to the center screw 314 and meshing with the worm gear 340. The rotation of the control motor 32 is transmitted to the center thread 314 via the meshing worm gear 340 and worm wheel 342. The rotation of the center thread 312 causes the nut member 314 to move axially. The axial movement of the nut member 314 causes the arm 316 to swing, which enables the switching action of the first-stage gear friction clutch 304 and the second-stage gear friction clutch 306.

[0076] A one-way clutch 348 is provided between the input side (drive motor 2 side) and the output side (input side of the first-stage gear set 301) of the friction clutch 304 for the first-stage gear. The operation of the one-way clutch 348 is related to... Figure 9 Similar to the flowchart, in the first-stage drive, the one-way clutch 348 is locked, and the engagement torque of the first-stage gear friction clutch 304 is 0. The torque of the drive motor 2 is transmitted to the first-stage gear set 301 via the one-way clutch 348. In addition, during the first-stage coasting, the engagement torque is applied to the first-stage gear friction clutch 304, thereby preventing the one-way clutch 348 from idling.

[0077] In this embodiment, since the threaded member 312 on the inner diameter side is solid, further miniaturization of the torque-thrust conversion mechanism is possible, contributing to cost reduction. Furthermore, since the axial force of the threaded member 312 can be maintained using the self-locking function of the worm gear 320, it is not necessary to... Figure 11 and Figure 14A , 14B The electromagnetic brake 48 described herein has cost advantages from this perspective. [Implementation method for making the actuator independent for two-stage speed change]

[0078] Figure 20 yes Figures 17-19 A modified embodiment of the implementation method is characterized in that, by employing a primary gear friction clutch 304 and a secondary gear friction clutch 306, the actuators are made independent, using dedicated primary gear friction clutch drive arms 350 and 352 respectively. The basic structure of the friction clutch drive arms 350 and 352 is similar to... Figures 17-19The swing arm 316 in the embodiment is the same, but the difference is that (i) a first-stage gear pusher 354 (and thrust bearing 355) is supported on the first-stage gear friction clutch drive arm 350, and a second-stage gear pusher 356 (and thrust bearing 358) is supported on the second-stage gear friction clutch drive arm 352; (o) a dedicated torque-thrust conversion mechanism 360 (composed of a center screw 362 and a nut 364) is provided for the swing of the first-stage gear friction clutch drive arm 350, and a dedicated torque-thrust conversion mechanism 366 (composed of a center screw 368 and a nut 370) is provided for the swing of the second-stage gear friction clutch drive arm 352; (ha) a rotary control motor 372 and a worm gear mechanism 374 are provided for the dedicated torque-thrust conversion mechanism 360 for the first-stage gear friction clutch, and a rotary control motor 376 and a worm gear mechanism 378 are provided for the dedicated torque-thrust conversion mechanism 366 for the second-stage gear friction clutch.

[0079] In this embodiment, since a primary gear friction clutch 304 and a secondary gear friction clutch 306 are used, dedicated actuators (primary gear friction clutch drive arm 350 and secondary gear friction clutch drive arm 352) are provided respectively. This allows for a design that eliminates the idle time during the switching between the primary gear friction clutch 304 and the secondary gear friction clutch 306, and eliminates the need for a one-way clutch 27. Figure 2 etc.), 69 ( Figure 15 This also helps to reduce shift shock. In addition, since there is no idling period during switching, the travel distance of the pusher can be shortened, thereby enabling the control motor to be miniaturized accordingly. Symbol Explanation

[0080] 2…drive motor; 4…two-stage transmission; 10… Input axis; 12… Output shaft; 14…outer shell; 16… Planetary gear mechanism; 20…wheel frame; 22…Stellar Gear; 24… gear ring; 26… Friction clutch; 27…one-way clutch; 28… Friction brake; 30…actuator; 32…Control the electric motor; 32-1… controls the output shaft of the motor; 34…push-up component; 34-3a… Friction brake drive unit for the pusher; 34-3b… Friction clutch drive unit for the pusher; 36… Torque-thrust conversion mechanism; 38…power transmission mechanism; 40… cylindrical screw (the inner diameter component of the present invention); 42… Cylindrical nut (outer diameter component of the present invention); 43a, 43b... thrust bearings; 44… drives the spur gear; 46…driven spur gear; 48…Electromagnetic brake; 52…brake pads; a…2-1 Target stroke of the drive component used for speed change; b…1-2 Target stroke amount for the drive component used in speed change;

[0081] 300… spur gear type two-stage transmission mechanism; 301… First-stage gear set; 301-1… Input side spur gear; 301-2… Output side spur gear; 302…Secondary gear set; 302-1…Input side spur gear; 302-2… Output side spur gear; 304… Friction clutch for primary gear; 306… Friction clutch for two-stage gears; 308…Actuator; 310… Torque-thrust conversion mechanism; 312… Screw component (inner diameter component of the present invention); 314…Nut component (outer diameter component of the present invention); 316…Swing arm (the thrust transmission component of the present invention); 318…push component; 32…Control the electric motor; 322…arm support pin; 324… Push component support pin; 332…arm drive pin; 334… drive pin hole; 350… First stage gear friction clutch drive arm; 352… Secondary gear friction clutch drive arm; 354… Actuator for primary gears; 356… A pusher for a secondary gear; 360… Torque-thrust conversion mechanism for primary gear; 362… Torque-thrust conversion mechanism for two-stage gears.

Claims

1. A two-stage transmission for an electric vehicle, wherein the two-stage transmission for an electric vehicle uses an electric rotary drive motor for driving wheels, characterized in that, The two-stage transmission for electric vehicles includes: shell; An input shaft, which is supported in a housing and connected to an electric rotary drive motor; An output shaft, which is supported by a housing and connected to the wheel side; The first gear mechanism is composed of gears that mesh with an output shaft to obtain a first-stage gear ratio when connected to an input shaft. The second gear mechanism is composed of gears that mesh with the output shaft to obtain a second-stage gear ratio that has the same direction of rotation but a higher gear ratio than the first-stage gear ratio when connected to the input shaft. The first multi-plate friction clutch, when engaged, transmits the rotation of the input shaft to the first gear mechanism to obtain the first-stage gear ratio; A second multi-plate friction clutch, coaxial with and axially separated from the first multi-plate friction clutch, achieves a second-stage gear ratio by transmitting the rotation of the input shaft to a second gear mechanism during engagement; and An actuator that selectively engages a first multi-plate friction clutch and a second multi-plate friction clutch. The actuator includes: a control motor as a torque source; meshing gears for torque transmission; an inner diameter member and an outer diameter member screwed together for converting torque into thrust; a thrust transmission member for transmitting thrust; and a clutch pressing member that presses against a first multi-plate friction clutch and / or a second multi-plate friction clutch for engagement by thrust, wherein the inner diameter member receives torque from the torque transmission gear, and the outer diameter member is slidably supported on the housing to convert the torque applied to the inner diameter member into thrust. A common set of actuators is used for the engagement of the first and second multi-plate friction clutches, and the clutch pressing member moves axially back and forth integrally with the outer diameter member via a thrust transmission member, thereby enabling selective engagement of the first and second multi-plate friction clutches. The outer diameter member and the thrust transmission member are configured as a double-layered cylindrical body consisting of an inner cylindrical part concentric with the central axis of the transmission, an outer cylindrical part, and a radial wall part that integrally connects them. The inner cylindrical part is screwed onto the outer side of the first multi-plate friction clutch and the second multi-plate friction clutch on the central axis. The outer cylindrical part slides freely onto the inner circumferential surface of the housing while facing the first multi-plate friction clutch or the second multi-plate friction clutch located on the proximity side. The clutch pressing member is fixed to the outer cylindrical part so as to be located between the first multi-plate friction clutch and the second multi-plate friction clutch.

2. The two-stage transmission for electric vehicles as described in claim 1, characterized in that, The clutch pressing member is composed of a stamped annular sheet extending radially between the first multi-plate friction clutch and the second multi-plate friction clutch, including a stamped part integrally connected to the outer cylindrical part at the outer peripheral end and used for pressing one of the first multi-plate friction clutch and the second multi-plate friction clutch at the inner peripheral end, and a stamped part used for pressing multiple of the first multi-plate friction clutch and the second multi-plate friction clutch at the middle part.

3. The two-stage transmission for electric vehicles as described in claim 2, characterized in that, The inner circumference of the clutch pressing member engages with the outer circumference in a slightly elastically deformable manner in the axial direction, thereby performing the engagement action of the first multi-plate friction clutch and the second multi-plate friction clutch.

4. The two-stage transmission for electric vehicles as described in claim 1 or 2, characterized in that, The input shaft and output shaft are coaxially arranged within the housing. The housing comprises three rotating elements: a wheel carrier that supports the pinion, and two gears with different numbers of teeth that mesh with the pinion. Two of these elements include planetary gear transmission mechanisms for connecting the input and output shafts respectively. The arrangement of the first and second multi-plate friction clutches relative to the three rotating elements and the housing is such that a first-stage gear ratio is achieved between the input and output shafts through the engagement of the first multi-plate friction clutch (achieved by the thrust transmission member) and the disengagement of the second multi-plate friction clutch. Thus, a planetary gear transmission mechanism is formed in the first gear mechanism. A second-stage gear ratio is achieved between the input and output shafts through the disengagement of the first multi-plate friction clutch (achieved by the thrust transmission member) and the engagement of the second multi-plate friction clutch. Thus, a planetary gear transmission mechanism is formed in the second gear mechanism.

5. The two-stage transmission for electric vehicles as described in claim 4, characterized in that, The first multi-plate friction clutch reduces speed between the input and output shafts by connecting one of the two rotating elements (not the wheel carrier) in the planetary gear transmission mechanism to the housing, thereby forming a first-stage gear ratio. The second multi-plate friction clutch forms a second-stage gear ratio by causing the rotating elements to rotate integrally between the input and output shafts. It also includes a one-way clutch, which is arranged in parallel with the first multi-plate friction clutch between the output shaft and the housing for transmitting drive torque.

6. The two-stage transmission for electric vehicles as described in claim 1 or 2, characterized in that, The first gear mechanism consists of spur gears meshing to obtain the first-stage gear ratio, and the second gear mechanism consists of spur gears meshing to obtain the second-stage gear ratio.

7. The two-stage transmission for electric vehicles as described in claim 6, characterized in that, It includes a one-way clutch, which is arranged side by side between the first gear mechanism, the input side and the output side for transmitting drive torque.

8. The two-stage transmission for electric vehicles as described in claim 1, characterized in that, The actuator includes a first actuator and a second actuator, wherein the first actuator participates in the engagement and disengagement of a first multi-plate friction clutch for setting the gear ratio of a first stage, and the second actuator participates in the engagement and disengagement of a second multi-plate friction clutch.

9. The two-stage transmission for electric vehicles as described in claim 8, characterized in that, In each actuator, the thrust transmission member is configured to be pivotally connected to the housing at one end, and at the other end, which is sandwiched between the first multi-plate friction clutch in the first group and the second multi-plate friction clutch in the second group, it is fitted with the swing arm of the outer diameter member at a position opposite to the diameter of the outer diameter member. The clutch pressing member is pivotally connected to the swing arm at a position opposite to the diameter. The forward and backward rotation of the swing arm caused by the axial forward and backward movement of the outer diameter member causes the clutch pressing member to participate in the engagement of the first multi-plate friction clutch in the first group and the engagement of the second multi-plate friction clutch in the second group.

10. The two-stage transmission for electric vehicles as described in claim 1, characterized in that, The meshing gears used for torque transmission consist of a pair of spur gears.

11. The two-stage transmission for electric vehicles as described in claim 1, characterized in that, The meshing gears used for torque transmission consist of a worm gear on the control motor side and a wheel meshing with the worm gear.

12. The two-stage transmission for electric vehicles as described in claim 1, characterized in that, The internal and external threaded components are configured with a large number of closely contacting balls in an infinitely circulating manner.

13. The two-stage transmission for electric vehicles as described in claim 1, characterized in that, It also includes an electromagnetic brake, which is used to maintain the engagement of the first multi-plate friction clutch and / or the second multi-plate friction clutch by braking the rotating shaft of the control motor.

14. The two-stage transmission for electric vehicles as described in claim 13, characterized in that, By applying the brakes to the rotating shaft of the control motor at predetermined intervals, the first multi-plate friction clutch and / or the second multi-plate friction clutch are re-engaged.

15. The two-stage transmission for electric vehicles as described in claim 13 or 14, characterized in that, The electromagnetic brake is used to brake the rotating shaft of the motor when it is not energized.

16. The two-stage transmission for electric vehicles as described in claim 5 or 7, characterized in that, When driving at the first gear ratio, the one-way clutch is restricted and the electromagnetic brake is disengaged. When coasting at the first gear ratio, the one-way clutch is free and the electromagnetic brake is engaged.

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