JP2023080192A - coupling device - Google Patents

Abstract

To provide a coupling device that is compact in an axial direction and is improved in response from input of power to clutch coupling.SOLUTION: A coupling device, interposed between a first shaft and a second shaft that can rotate about an axis, is equipped with a casing that is stationary with respect to the axis, a stator that is prevented from rotating with respect to the casing, and generates a magnetic flux parallel with the axis according to input of power, a rotor that opposes to the stator separately in an axial direction, and receives the magnetic flux to generate torque around the axis, a conversion mechanism that is drivingly coupled to the rotor to convert the torque into thrust force in a direction along the axis, and is equipped with a thrust member exerting the thrust, a clutch that opposes to the thrust member and receives the thrust force to couple the first shaft to the second shaft, and a bearing that is interposed between the rotor and the casing, and is disposed so as to overlap with the rotor in the axial direction.SELECTED DRAWING: Figure 4

Description

The following disclosure relates to a coupling device interposed in the driveline for the purpose of controlling rotation, for example in an automobile, and in particular to a coupling device that is compact and allows for quick response.

For example, in a four-wheel drive (4WD) vehicle in which the engine/motor is mounted in the front part of the vehicle body and the propeller shaft extending backward is used to apply power to the rear wheels, a cup with a built-in clutch that intermittently transmits power. A part-time 4WD vehicle can be realized if the ring device is interposed on the propeller shaft.

Since an extremely large torque is applied to such a clutch, a large driving force is required for its connection. One solution to this problem is to place a large motor outside the coupling device, obtain a large thrust force by using a multi-stage reduction gear and a cam mechanism, and use this as a drive force for the clutch. Alternatively, there has been proposed a configuration in which the motor is incorporated in the device and coaxial with the propeller shaft, avoiding attaching the motor to the outside.

Patent Documents 1 to 3 disclose related techniques.

JP 2013-204701 A International Patent Application Publication WO2015/068822 JP 2018-13175 A

The configuration in which the motor is coaxial with the propeller shaft significantly saves space for the entire coupling device including the motor. In addition, since the diameter of the motor is inevitably increased, a certain amount of torque can be expected, and therefore the response from the application of electric power to the engagement of the clutch can be made to a satisfactory level. However, there is limited room for further improving the response or miniaturizing without degrading the response. The apparatus disclosed below is devised to overcome such problems.

According to one aspect, a coupling device interposed between a first shaft and a second shaft each rotatable about an axis comprises a casing stationary with respect to said axis and a casing rotatable with respect to said casing. a stator which is stationary and produces a magnetic flux parallel to said axis in response to the application of electric power; a rotor spaced apart in the direction of said axis and opposed to said stator for receiving said magnetic flux and producing a torque about said axis; A conversion mechanism drivingly connected to a rotor to convert the torque into a thrust force along the axis, the conversion mechanism comprising a thrust member for exerting the thrust force; a clutch that receives the thrust force and connects the first shaft to the second shaft; a bearing;

FIG. 1A is a schematic diagram of a four-wheel drive vehicle. FIG. 1B is a schematic diagram of a coupling device interposed on a propeller shaft, according to one embodiment. FIG. 2 is an exploded perspective view of an axial gap motor used in a coupling device. FIG. 3A is a cross-sectional elevational view of an axial gap motor showing a pair of rotors and stators according to one example. FIG. 3B is a cross-sectional elevational view of an axial gap motor showing a pair of rotors and stators according to another example. FIG. 4 is a cross-sectional elevational view of a coupling device according to the example of a planetary gear. FIG. 5 is a cross-sectional elevational view of a coupling device according to another example of planetary gears. FIG. 6 is a cross-sectional elevational view of a coupling device according to the example of a cycloidal gear; FIG. 7 is a cross-sectional elevational view of a coupling device according to yet another example of a planetary gear. FIG. 8 is a cross-sectional elevational view of a coupling device according to the example of a ball screw. FIG. 9 is a sectional elevational view of a coupling device according to the example of a dog clutch.

Several exemplary embodiments are described below with reference to the accompanying drawings. In the following description and in the appended claims, unless otherwise specified, axis means the central axis of the stator and rotor, which usually coincides with the axis of rotation of the shaft to which the coupling device connects. It should be especially noted that the drawings are not necessarily drawn to scale and therefore the dimensional relationships to each other are not limited to those shown.

Referring to FIG. 1A, a four-wheel drive vehicle 1 generally includes an engine/motor 3 and a transmission 5 . The torque generated by the engine/motor 3 is distributed to the front wheels 13R, 13L via the transmission 5. Part of the torque is drawn out to the propeller shaft 11 via the power transfer unit 7 and distributed to the rear wheels 15R, 15L via the final drive 9. Coupling devices or equivalent clutch devices, described below, are interposed in any such driveline to control rotation.

For example, according to the example shown in FIG. 1B, the coupling device 10 is interposed between the propeller shaft 11 and the final drive 9 . The coupling device 10 is provided with a clutch 17, and when the clutch 17 is engaged, torque is transmitted from the propeller shaft 11 to the final drive 9 so that the four-wheel drive vehicle 1 travels in the four-wheel drive mode, and when disengaged, the two-wheel drive. run in mode. An actuator 19 is coupled to the clutch 17 to control its engagement/disengagement.

Alternatively, although not shown, the coupling device may be interposed between the engine/motor 3 and the transmission 5, for example. It can be used to intermittently switch the output of the engine/motor 3 . Alternatively, the transmission 5 may incorporate a clutch device, which will be described below, for the purpose of synchronizing gear changes. Alternatively, the differential device may incorporate a clutch device for the purpose of performing lockup or free-running operation. Alternatively, coupling devices or clutch devices can be used for axle disconnects, axles, between the main drive side and the sub-drive side, power take-offs, and the like. Needless to say, more than two of these can be used.

Further, an example in which the coupling device 10 is interposed between one shaft and another shaft will be described below, but the other shaft may be a fixed member. According to such an example, the device can be used for the purpose of limiting or stopping the rotation of one shaft, for example in shift parking or reverse mechanisms.

For convenience of explanation, the following embodiments are mainly described based on the example shown in FIG. 1B, but it goes without saying that any of the above examples can be implemented based on the description.

Referring to FIG. 2, the actuator 19 can utilize an axial gap motor 21 . The axial gap motor 21 is a substantially circular motor that can be arranged coaxially with the axis X of the coupling device 10 and can generate torque around the axis X. As shown in FIG.

The stator 23 is a stationary member that is prevented from rotating, and is composed of a plurality of cores 23B arranged around the axis X and a plurality of electromagnetic coils 25 surrounding the cores 23B. Each coil 25 and core 23B combination is configured to produce a magnetic flux parallel to the X-axis.

The rotor 27 is made of a magnetic material, is a substantially circular body symmetrical about the axis X, and can perform rotational motion R about the axis X without being prevented from rotating. The rotor 27 is arranged slightly away from and opposite the stator 23 in the direction of the axis X so that the stator 23 can receive the generated magnetic flux. Rotor 27 may also comprise a plurality of projections 27P projecting in the direction of axis X towards stator 23 .

3A in combination with FIG. 2, the rotor 27 and the stator 23, especially the core 23B and the projections 27P, are in close proximity in the direction of the axis X, so that the stator 23 does not leak magnetic flux. acceptable to The core 23B and the protrusion 27P may each have a flat surface on the surfaces facing each other, but may each have a three-dimensional structure in order to increase the area through which the magnetic flux passes. An example of such a structure is, as shown in FIG. 3B, a plurality of ribs 23R, 27R extending in the circumferential direction and intertwined with each other, but the structure is of course not limited to this. Such a structure contributes to an increase in torque or to an improvement in power utilization efficiency.

A drive circuit using a switching element such as an insulated gate bipolar transistor (IGBT) is normally used to drive the axial gap motor 21 . That is, a switching element is used to generate alternating current or pulse current having a phase difference, and by inputting this to a plurality of electromagnetic coils 25 , torque is generated in the rotor 27 .

The generated torque is proportional to the square of the radius and the axial length of the surface through which the magnetic flux passes in the radial gap motor, but is proportional to the cube of the radius in the axial gap motor. Since there is relatively more room in the radial direction than in the axial length in the coaxial arrangement with the coupling device 10, the use of the axial gap motor 21 is advantageous for increasing the output, or reducing the size for the same output. It is advantageous to

4 to 9, according to the example shown in FIG. 1B, the coupling device 10 comprises a propeller shaft 11 rotatable about axis X and a final drive shaft 11, also rotatable about axis X. It is interposed between the shaft communicating with 9. The shaft that communicates with the final drive 9 is not depicted in these figures, but connects to the left hand spline 73 in each figure.

The entire actuator 19 and clutch 17 are housed in a casing. The casing may, but not necessarily, be divided into two or more parts 31, 33 which are joined together by bolts or the like after the internal parts have been assembled. Both the propeller shaft 11 and the other shaft can be connected to the coupling device 10 by inserting them from the left in the drawing after the parts 31 and 33 are connected to each other.

The stator 23 is fixed to a portion 31 of the casing, as shown on the right hand side of each figure. The rotor 27 is supported by the same portion 31 via bearings 35, but it may be supported by another portion 33 instead of the portion 31 as long as the gap to the stator 23 is properly maintained. Further, although the details will be described later, since a significant force is not applied to the rotor 27 in the axial direction, a radial bearing such as a ball bearing can be used as the bearing 35, or a sliding bearing can be used. good.

Only one bearing 35 can be used to support the rotor 27 . The bearings 35 may be interposed on the inner periphery of the rotor 27 as shown in FIGS. In any case, the bearing 35 can be arranged radially between the rotor 27 and the part 31 of the casing. 4, 7 and 8, they can also be positioned so that they overlap each other in the axial direction. Such an arrangement contributes to reducing the axial dimension of the coupling device 10 and helps prevent radial eccentricity of the rotor 27 .

The bearing 35 may also axially at least partially overlap the stator 23, as shown in FIGS. As can be seen from these figures, there is a spatial margin outside or inside the stator 23 in the radial direction. contributes to reducing Moreover, since these positions are close to the stator 23, high accuracy can be ensured, and as a result, the accuracy of the position of the rotor 27 with respect to the stator 23 can be improved. This contributes to stable operation.

The actuator 19 further includes a conversion mechanism 41 that converts torque into a thrust force along the X axis. The conversion mechanism 41 converts torque generated by the axial gap motor 21 into thrust force and applies it to the clutch 17 . The conversion mechanism 41 has, for example, a thrust member 43 for exerting a thrust force, and the thrust member 43 contacts one end of the clutch 17 to apply the thrust force to the clutch 17, thereby connecting it.

The conversion mechanism 41 may include a reduction mechanism to multiply the torque, for example the reduction mechanism may be a planetary gear mechanism as shown in FIGS. According to such an example, the rotor 27 is coupled to, for example, a carrier 45 and planetary gears 47 are rotatably supported by the carrier 45 . The planetary gear mechanism also comprises a stationary member 51 and a driven member 55 each having gear teeth of different numbers. The planetary gear 47 is geared with the stationary member 51 and the driven member 55, and the driven member 55 rotates at a speed reduced according to the difference in the number of teeth.

The conversion mechanism 41 also includes a cam mechanism that converts rotary motion into linear motion. In this embodiment, the cam mechanism is a cam ball 53 interposed between a stationary member 51 and a driven member 55 and an inclined cam surface provided on one or both of members 51 and 55 . When the rotor 27 rotates about the axis X, the cam ball 53 rolls on the cam surfaces of the members 51 and 55 and presses the driven member 55, thereby converting torque into thrust force.

A stationary member 51 is seated and detented against the portion 31 or portion 33 of the casing to bear the reaction force of the thrust force. As understood from the above description, the conversion mechanism 41 is mechanically connected to the rotor 27 only in the circumferential direction, and the reaction force in the axial direction is borne by the casing. No reaction force is transmitted to the member.

In the example of FIG. 4, the gear teeth of members 51 and 55 are external teeth, and planetary gear 47 meshes with the outside of these. In the example of FIG. 5, the planetary gear 47 is an internal tooth and meshes with the inner side. In either case, the carrier 45, planetary gears 47, and driven member 55 are indirectly supported by the stationary member 51 by means of gear connections, so no ball bearings or roller bearings are required to support them. Of course, bearings may intervene for the stability of each member.

Thrust member 43 may be coupled to driven member 55, as shown in FIG. Alternatively, the driven member 55 may be integral with the thrust member 43 as shown in FIG.

A thrust bearing 39 and a pressure plate 59 may be interposed between the thrust member 43 and the clutch 17 . Thrust bearing 39 allows relative rotation of pressure plate 59 and clutch 17 with respect to conversion mechanism 41 . The pressure plate 59 presses against the clutch 17 without relative rotation.

A spring 60 may be interposed in a direction to push back the pressure plate 59 when no thrust force is applied. A leaf spring or a wave spring can be used for the spring 60 . For example, the pressure plate 59 extends radially inwardly or outwardly and is appropriately bent axially to face the inner drum 71 or the outer drum 75 . A spring 60 is interposed at , so that the biasing force is applied to the pressure plate 59 . A Z-washer, separate from the pressure plate 59 and similarly bent in a Z-shape, may be utilized against which the spring 60 abuts. Alternatively, spring 60 may directly abut thrust member 43 . If the spring 60 is interposed, the clutch 17 is rapidly switched from engagement to disengagement when disengaging, and the disengagement is maintained when no thrust force acts, so the response of the clutch 17 to external control is improved. improves.

The reduction mechanism is not limited to the planetary gear mechanism described above, and a cycloid gear mechanism as shown in FIG. 6 can be used. According to such an example, the gear member 61 is supported by the rotor 27 so as to rotate around the eccentric axis EX which is slightly eccentric to the axis X. A bearing 67 such as a ball bearing may be interposed therebetween to enable smooth rotation. The gear member 61 has gear teeth 63 on its outer periphery and the stationary member 51 has an internal gear 65 to mesh with the gear teeth 63 . The cam mechanism engages member 61, and as rotor 27 rotates about axis X, a reduced rotation occurs in driven member 55, with cam balls 53 rolling between members 51 and 55 to thrust torque. convert to force.

4 and 5, the reaction force is borne by the stationary member 51 seated on the casing, so the reaction force is not transmitted to the gear member 61 or the rotor 27. FIG. Also in this example, the driven member 55 itself may also serve as the thrust member 43, or a separate thrust member may intervene. Needless to say, a thrust bearing 39 may be interposed between the thrust member and the clutch 17.

In the examples shown in FIGS. 4-7, the conversion from rotary motion to linear motion was by a cam mechanism, but of course other mechanisms could be used. FIG. 8 shows an example using a ball screw 57. FIG. In such an example, the stationary member 51 and the driven member 55 are threaded to engage with each other via balls, and the combination of the members 51 and 55 constitutes a ball screw 57 . Driven member 55 is coupled to or integral with thrust member 43 .

When the rotor 27 rotates around the axis X and the driven member 55 is rotated with respect to the stationary member 51 by the planetary gear mechanism, the driven member 55 advances in the axial direction due to the action of the ball screw 57, and the thrust member 43 is passed through the clutch. 17 are concatenated. Of course, instead of the planetary gear mechanism, a cycloidal gear mechanism or other reduction mechanism can be used.

Also, in the examples shown in FIGS. 4 to 8, the output of the motor 21 is multiplied using a speed reduction mechanism, or the speed reduction mechanism may be omitted. In the example shown in FIG. 9, the conversion mechanism 41 is simply a cam mechanism that converts rotary motion into linear motion, and torque of the rotor 27 is directly converted into thrust force of the thrust member 43 . Alternatively, a ball screw or other link mechanism may be used instead of the cam mechanism. Although it is disadvantageous in terms of thrust force strength, such a simple structure is suitable for combination with dog clutches that do not require a large thrust force to maintain the engagement once engaged, such as the illustrated dog clutch 79.

Clutch 17 can be any type of clutch. A large thrust force can be obtained by combining a relatively large torque generated by the axial gap motor 21 with a reduction mechanism such as a planetary gear mechanism. To take advantage of this, it would be preferable to combine it with a friction clutch, especially a multi-disc clutch as shown in FIGS.

For example, the inner drum 71 connected to one disk group of the multi-plate clutch can be connected to the propeller shaft 11 by providing connecting means such as splines on its inner circumference. The outer drum 75 associated with the other group of discs may be provided with coupling means such as splines 73 to be coupled with a shaft communicating with the final drive 9 .

Alternatively, instead of a friction clutch, a dog clutch, particularly a dog clutch 79 as shown in FIG. 9, may be utilized. In this case, for example, a return spring 83 may be interposed between the clutch teeth in order to facilitate disengagement of the clutch. Also, the ratchet mechanism may be used in the direction of maintaining the clutch teeth engaged or disengaged.

In either example, a bearing 77 may be interposed between the inner drum 71 and the outer drum 75 . Since no thrust force acts on such bearings, radial bearings such as ball bearings can be used, or plain bearings may be used. A bearing 81 may also be interposed between the outer drum 77 and the propeller shaft 11 or between the outer drum 77 and the casing. Since no thrust force acts on such bearings, radial bearings such as needle bearings can be used, or sliding bearings can be used. These bearings align the propeller shaft 11, the clutch 17 and the casing with each other.

A thrust bearing 37 may be interposed between the back surface of the clutch 17 , for example the end surface of the outer drum 75 , and the portion 33 of the casing to receive the thrust force from the conversion mechanism 41 . This helps the casing bear the thrust force and helps the clutch 17 to rotate smoothly.

As can be seen from FIGS. 4-6 and 8-9, by utilizing an axial gap motor, there is still space available around the outer circumference of the rotor 27. FIG. Alternatively, a space can be left on the inner circumference of the rotor 27 as shown in FIG. This space can be used to install an encoder 29 that reads the number of revolutions of the rotor 27, for example. Of course, other various sensors and the like may be installed.

As can be understood from the above description, the coupling device has a dimensional margin in the radial direction, so a relatively large output can be obtained by using the axial gap motor. By combining this with a conversion mechanism including a speed reduction mechanism, it is possible to improve the response related to the engagement of the clutch and reduce the size of the entire device.

Also, even if several bearings are required for clutch shaft alignment, the number of bearings required for the motor can be reduced or omitted, which also contributes to downsizing and structural simplification of the coupling device. can be pursued.

Further, the thrust force generated by the conversion mechanism is borne exclusively by the clutch and the conversion mechanism, and the thrust force loop is completed by supporting the back surface of the clutch and the stationary member by the casing, and the thrust force is transferred to other components. not reach. This reduces the need for supporting or reinforcing other components, which also contributes to compactness and structural simplification of the device.

Although several embodiments have been described, modifications and variations of the embodiments are possible based on the above disclosure.

Claims (6)

A coupling device interposed between a first shaft and a second shaft each rotatable about an axis,
a casing stationary with respect to said axis;
a stator that is rotatably fixed with respect to the casing and generates a magnetic flux parallel to the axis in response to application of electric power;
a rotor spaced apart in the direction of the axis and facing the stator for receiving the magnetic flux and producing a torque about the axis;
a conversion mechanism drivingly coupled to the rotor to convert the torque into a thrust force along the axis, the conversion mechanism comprising a thrust member for exerting the thrust force;
a clutch that faces the thrust member and receives the thrust force to connect the first shaft to the second shaft;
a bearing interposed between the rotor and the casing and arranged so as to overlap the rotor in the axial direction;
Coupling device with a thrust bearing that is interposed between the casing and the clutch and bears the thrust force to rotatably support the clutch;
2. The coupling device of claim 1, further comprising. further comprising a thrust bearing that is interposed between the casing and the clutch and bears the thrust force to rotatably support the clutch;
2. The coupling device of claim 1, wherein said converting mechanism comprises a stationary member for receiving a reaction force of said thrust force, said stationary member seated on said casing to bear said reaction force on said casing. 4. The coupling device of claim 3, wherein the conversion mechanism is only circumferentially connected to the rotor with respect to the axis, so that the reaction force does not act on the rotor. 2. The coupling device of claim 1, wherein the bearing is arranged to axially overlap the stator. 2. The coupling device of claim 1, wherein said rotor is rotatably supported in said casing only by said bearing.

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