Axial drive actuator

Abstract

Provided is an actuator that operates an internal clutch of a device capable of rotating about a shaft from the outside, the actuator including: a drive unit including a plurality of electromagnetic coils arranged about the shaft and positioned to generate magnetic flux in a direction parallel to the shaft; an armature disposed coaxially with the shaft, movable in the axial direction, and axially opposed to the drive unit; and a plunger coupled to the armature and transmitting axial movement to the clutch.

Description

Technical Field

[0001] The following disclosure relates to an actuator for axially driving a clutch inside a rotating machine such as a differential from the outside, and more particularly to an actuator that can integrate sensors, etc., without increasing size. Background Technology

[0002] Vehicles and rotating machinery often utilize clutches to selectively operate and stop their functions. For example, a locking differential incorporates a claw clutch; normally, the claw clutch is disengaged, allowing differential movement between the output shafts, and when engaged by an external actuator, the differential is locked. Actuators can utilize hydraulic cylinders, cam mechanisms using motors, or solenoid actuators, among others.

[0003] Even when the actuator is operational, the clutch may occasionally engage and be damaged under rare conditions, such as when the clutch teeth are in an unsuitable meshing position. Furthermore, due to the viscosity and magnetization of the lubricating oil, the clutch teeth may temporarily stick together, potentially causing a delay in release. In other words, switching the actuator on / off may not correspond to the clutch engaging / disengaging. To prevent unexpected movements of rotating machinery, additional devices for detecting clutch engagement are often required.

[0004] Patent documents 1 to 3 disclose the relevant technologies.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2015-219944

[0008] Patent Document 2: International Patent Application Publication WO2018 / 109874A1

[0009] Patent Document 3: Japanese Patent Application Publication No. 2004-208460 Summary of the Invention

[0010] According to any of the above techniques, it is impossible to attach a detection device unless there is sufficient free space outside the actuator. Furthermore, when the detection device is fixed to the bracket of the rotating machinery, the problem arises of how to precisely position the detection device relative to the rotating machinery.

[0011] The actuator disclosed below was invented in view of the above-mentioned problems.

[0012] According to one embodiment, an actuator that operates an internal clutch of a device capable of rotating about an axis from the outside comprises: a drive unit having a plurality of electromagnetic coils arranged about the axis and each oriented to generate magnetic flux in a direction parallel to the axis; an armature coaxially disposed with the axis, axially movable, and axially opposed to the drive unit; and a plunger engaged with the armature to transmit axial motion to the clutch. Attached Figure Description

[0013] Figure 1 It is a 3D diagram of a differential with an actuator.

[0014] Figure 2 It is a cross-sectional elevation view of a differential equipped with an actuator.

[0015] Figure 3 It is an exploded perspective view of the actuator, including the clutch components.

[0016] Figure 4 It is a 3D view of a differential with the clutch assembly assembled.

[0017] Figure 5 It is a cross-sectional elevation view of the actuator and its surrounding components. Detailed Implementation

[0018] Hereinafter, several exemplary embodiments will be described with reference to the accompanying drawings. In the following description and appended claims, unless otherwise specified, the shaft refers to the central shaft of the clutch, and is generally also consistent with the rotating shaft of rotating machinery. It should be noted that the drawings are not necessarily shown at an exact scale, and therefore the dimensional relationships are not limited to those shown in the figures.

[0019] Main reference Figure 1 , Figure 2 In this embodiment, the actuator 1 is used in combination with a device that rotates about axis X, such as a differential 3, for the purpose of operating the clutch 5 inside it from the outside. It is not limited to a differential and can be combined with any rotating machinery that transmits power to the vehicle, such as a transmission, power transmission unit (PTU), or coupling device, but is not necessarily limited thereto. Furthermore, the clutch 5 is, for example, a so-called claw clutch with claw-shaped teeth, but it can also be a clutch that transmits torque through a meshing structure such as a closed clutch, or a friction clutch.

[0020] The actuator 1 generally includes a drive unit 7, an armature 9 that is axially movable and attracted by the drive unit 7, a plunger 11 that transmits the axial movement of the armature 9, and a clutch component 13 driven by the plunger 11. In this example, the clutch component 13 is configured to mesh with a side gear 15, and the combination of the clutch component 13 and the side gear 15 constitutes a clutch 5. Of course, the side gear 15 can also be replaced by other elements to form the clutch 5.

[0021] The differential 3 includes a housing 17, for example, with a flange 17F on its outer periphery, and rotates about axis X by receiving torque via a gear ring fixed to the flange 17F. Furthermore, the differential 3 has a differential gear set inside the housing 17, which differentially outputs the received torque to a pair of side gears. When the clutch 5 is released, the differential between the side gears is allowed, and when the clutch 5 is engaged, the differential is locked. In the illustrated example, the clutch 5 is always released, and the clutch 5 is engaged when power is supplied to the actuator 1. Conversely, it can also be configured such that the clutch 5 is released when power is supplied to the actuator 1. Such a configuration can be easily achieved, for example, by reversing the drive unit 7 and the armature 9. Alternatively, it can be configured such that the drive unit 7 and the armature 9 are reversed, and the clutch 5 is engaged when power is supplied to the actuator 1.

[0022] Combination Figure 1 , Figure 2 Reference Figure 3 The clutch assembly 13 and the plunger 11 connected thereto can rotate about axis X together with the differential 3, but the actuators 1, especially the drive unit 7 and the armature 9, are prevented from rotating about axis X. The prevented rotation can be achieved using any unit, but in the illustrated example, the housing 27 that houses the drive unit 7 has a flap 33, which engages with a part of the bracket to prevent rotation.

[0023] The drive unit 7 includes multiple electromagnetic coils 21 arranged around axis X. Each electromagnetic coil 21 is oriented to generate a magnetic flux F in a direction parallel to axis X. Figure 3 In this design, the electromagnetic coils 21 are depicted as adjacent in the circumferential direction, but they can also be separated from each other. Furthermore, their number can be any number exceeding one. Their configuration can also be asymmetrical, but it is preferred that the multiple electromagnetic coils 21 are arranged symmetrically about axis X. This helps prevent uneven driving force.

[0024] To efficiently extract and guide the magnetic flux F, the drive unit 7 also has multiple iron cores 23 corresponding to each electromagnetic coil 21. Figure 3In this design, the electromagnetic coil 21 and the iron core 23 appear to be separate, but they can also be integrated by directly winding the electromagnetic coil 21 onto the iron core 23. To hold multiple iron cores 23 and fix them relative to the housing 27, an annular plate 25 can be used. The plate 25 has holes or recesses for the iron cores 23 to fit into each other, or the iron cores 23 and the plate 25 can also be integrated.

[0025] The actuator 1 preferably has a housing 27 that prevents rotation relative to the bracket. At least the electromagnetic coil 21 and the iron core 23 are preferably housed in the housing 27, and the plate 25 is covered and engaged with the housing 27, thereby preventing rotation as a whole. In addition, the housing 27 is axially prevented from disengaging, for example, relative to the boss 17B of the housing 17, and the electromagnetic coil 21 and the iron core 23 are also axially stationary. For example, a ring 35 pressed into the boss 17B can be used to prevent disengagement, but it is not a limitation. The wires of the plurality of electromagnetic coils 21 are gathered to form a cable 29 that leads out of the housing 27.

[0026] Armature 9 is a disk-shaped component about axis X and is made wholly or partially of magnetic material. Armature 9 is coaxially arranged with axis X and is axially opposed to or close to drive unit 7, particularly its core 23. Preferably, armature 9 is also housed in housing 27 and is antirotated about axis X, but axially movable. However, armature 9 can also be rotatable, in which case it can rotate in addition to axial movement. Furthermore, armature 9 can also have a structure that efficiently receives magnetic flux F, for example, by having blocks protruding towards each core 23 corresponding to it. Alternatively, only the blocks may be made of magnetic material, while the other parts are made of non-magnetic material.

[0027] As readily understood, when the electromagnetic coil 21 is energized by power supplied through cable 29, the armature 9 is attracted by the drive unit 7 through the magnetic flux F, thereby moving axially. To return the armature 9 to its initial position when power is cut off, for example, a spring 19 can be sandwiched between the plate 25 and the armature 9. The spring 19 exerts a force on the armature 9 in the direction of separation from the drive unit 7.

[0028] The plunger 11 is positioned between the armature 9 and the clutch assembly 13, transmitting the axial movement of the armature 9 to the clutch assembly 13. Engagement Figures 1 to 3 and refer to Figure 5 The plunger 11 has a short cylindrical portion 11C symmetrical about the axis X on its inner circumference. The cylindrical portion 11C is slidably fitted into the boss portion 17B of the housing 17, thereby positioning the plunger 11 relative to the housing 17 and making it axially movable.

[0029] A bearing 31 may be sandwiched between the armature 9 and the plunger 11. The bearing 31 is fitted into, for example, the cylindrical portion 11C of the plunger 11 and is fixed thereto, for example, by a retaining ring. The armature 9 may also have a corresponding short cylindrical portion on its inner circumference, into which the bearing 31 is embedded and fixed thereto, for example, by a retaining ring. Thus, the axial movement of the armature 9 is transmitted to the plunger 11 in two directions, and the plunger 11 is rotatable relative to the armature 9.

[0030] Bearing 31 can be a thrust bearing, but the applied thrust is not that large, so a general ball bearing can be used. Of course, other types of bearings, such as roller bearings, can also be used.

[0031] Combination Figure 3 Reference Figure 4 The plunger 11 is located on the outside of the housing 17 of the differential 3, while the clutch component 13 is located inside. The clutch component 13, for example, has claw-shaped teeth 13T on its inner surface for forming the clutch 5. From its opposite surface, one or more legs 13L extend axially outward. Corresponding to the legs 13L, the housing 17 has through holes 37 through which the legs 13L protrude to the outside. The plunger 11 and the clutch component 13 are engaged by these legs 13L, thereby moving together axially and rotating together about axis X. Bolts can be used for engagement, or other suitable units can also be used.

[0032] Combination Figure 2 , Figure 3 Mainly refer to Figure 5 When the electromagnetic coil 21 is energized by power supplied through cable 29, the armature 9 is attracted to and driven by the drive unit 7 through the magnetic flux F. The plunger 11 moves the clutch assembly 13 axially, engaging the clutch 5. If the power is cut off and the magnetic flux F disappears, the plunger 11 is driven in the opposite direction mainly by the action of the spring 19, releasing the clutch 5. To facilitate release, for example, a spring 41 may be additionally clamped between the side gear 15 and the clutch assembly 13, or the spring 41 may replace the spring 19.

[0033] In the embodiments described above, the electromagnetic coil 21 is stationary in the axial direction, while the armature 9 is movable and drives the plunger 11. Alternatively, the electromagnetic coil 21 may be movable and drive the plunger 11. In this case, a suitable component coupled to the electromagnetic coil 21, in the above embodiment being a core 23 or a plate 25, may be coupled to the plunger 11, or it may be coupled to the electromagnetic coil 21 and the plunger 11 with separate intermediate components. Whether these components are referred to as a core or an armature depends on the specific circumstances.

[0034] According to this embodiment, unlike conventional solenoid actuators, there is no structure where a wire is continuously wound multiple times around an axis. The multiple electromagnetic coils 21 are independent of each other and do not need to be in circumferential contact, thus allowing other elements to be arranged between the electromagnetic coils 21. One example is a proximity sensor. By using a proximity sensor to detect whether the armature 9 is in a distant or approaching state, it is possible to determine whether the clutch 5 is engaged or disengaged.

[0035] Alternatively, one or more of the multiple electromagnetic coils 21A can be used to detect the position of the armature 9. For example, when the armature 9 approaches or disengages, the electromagnetic coil 21A generates an electromotive force, thus enabling detection to determine the engagement / disengagement of the clutch 5. For such detection purposes, a cable can be drawn from this electromagnetic coil 21A independently of the other electromagnetic coils 21.

[0036] Alternatively, the impedance change of the electromagnetic coil 21A can be detected based on the position of the armature 9. Alternatively, a proximity sensor, a contact sensor, or a mechanical switch can be used instead of the electromagnetic coil 21A.

[0037] Regardless, components linked to the clutch assembly 13, such as the armature 9, are located inside the actuator 1, and the device for detecting its position can also be housed inside the actuator 1. Consequently, the device for detecting whether the clutch 5 is engaged or disengaged can be housed inside the actuator 1, eliminating the need for an external detection device. This embodiment requires no external free space for the actuator 1, making it compact. No additional detection device is needed on the bracket, and the positional relationship between the bracket and the actuator 1 does not require particular precision. The shape of the actuator 1 is compatible with existing shapes, therefore the device of this embodiment can be used interchangeably with existing devices.

[0038] Several implementation methods have been described, but modifications or variations can be made to the implementation methods based on the above disclosure.

Claims

1. An actuator that operates an internal clutch of a device rotatable about an axis from the outside, characterized in that, have: A drive unit comprising a plurality of electromagnetic coils arranged around the axis and oriented to generate magnetic flux in a direction parallel to the axis; An armature, which is coaxially arranged with the shaft, is axially movable, and is axially opposed to the drive unit, and is attracted by the drive unit through the magnetic flux; The leg extends axially outward from the clutch and protrudes outward through a through hole in the housing of the device; as well as A plunger, which engages with the armature and the leg, and transmits axial motion to the clutch.

2. The actuator according to claim 1, characterized in that, The plunger has a cylindrical portion that is symmetrical about the axis and is slidably fitted into the device.

3. The actuator according to claim 1, characterized in that, At least one of the plurality of electromagnetic coils is led out independently of the other electromagnetic coils.

4. The actuator according to claim 1, characterized in that, It also includes a spring that applies force to the armature in the direction of separation from the drive unit.

5. The actuator according to claim 1, characterized in that, The drive unit stops rotating around the axis.

6. The actuator according to claim 1, characterized in that, The plunger is rotatably engaged relative to the armature and rotates together with the clutch about the shaft.

7. The actuator according to claim 1, characterized in that, It also includes a sensor, which is disposed between the plurality of electromagnetic coils or in place of one of the plurality of electromagnetic coils, to detect whether the armature is in a distant or near state.

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