Electric motor device

Abstract

Provided is an electric motor device with which space saving and cost reduction are achieved and also stable braking can be performed. An axial gap type electric motor device (DM) comprises: a housing (3); a stator (4) supported by the housing (3); and a rotor (5) rotatably supported by the housing (3) and rotating facing the stator (4) in the axial direction (C1). The rotor (5) includes: a main shaft (9) rotatably supported by the housing (3) and the stator (4); and a field mechanism (8) rotatably synchronized with the main shaft (9) and slidably provided in the axial direction (C1). The electric motor device is provided with a field mechanism restricting means (7) that, when the field mechanism (8) is slid in the axial direction (C1), brakes the rotation of the rotor (5) by the frictional force acting on a contact surface formed by the field mechanism (8) being brought into contact with the housing (3) or the stator (4) and restricts the axial position of the field mechanism (8).

Description

Electric motor device Related Applications

[0001] This application claims priority from Japanese Patent Application No. 2024-032117, filed March 4, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to an electric motor device, and to a technique that enables space saving, cost reduction, and stable braking.

[0003] The following technologies have been proposed as electric motor devices: 1. Electric motor equipped with an electromagnetic brake (Patent Document 1). 2. Electric vehicle equipped with an electric motor with regenerative braking function (Patent Document 2). 3. Electric motor control system with short-circuit braking function (Patent Document 3). 4. Automatic guided vehicle driven by a motor (Patent Document 4).

[0004] Japanese Patent Laid-Open No. 9-327152 Japanese Patent Laid-Open No. 2016-1959 Japanese Patent Laid-Open No. 2019-58036 Japanese Patent Laid-Open No. 2021-142768

[0005] For example, in applications where an electric motor is used, an electric motor provided with an electromagnetic brake for the purpose of braking and stopping rotation more stably has been proposed, as in the electric motor device described in Patent Document 1. Providing a separate electromagnetic brake on the motor requires space for installing the electromagnetic brake, wiring for the electromagnetic brake, a control device, etc. This can result in problems with increased motor installation space and costs.

[0006] For example, Patent Document 2 describes a technology for generating a rotational braking force by regenerative braking of a motor. However, at low speeds where the angular velocity is zero or close to zero, the motor is stopped by angle servo control. Therefore, there is a possibility that the motor will rotate when an external force that would cause it to rotate is applied. To implement a regenerative system such as that described in Patent Document 2, the power source must be capable of charging regenerative power. However, it may be difficult to generate a rotational braking force, for example, when a power converter without a regenerative function is used as the power source, or when a regenerative battery is nearly fully charged and difficult to charge.

[0007] For example, as described in Patent Document 3, a technology has been proposed that generates a rotational braking force regardless of the power supply specifications by shorting the terminals of the motor coil, i.e., controlling the potential difference between the coils to be approximately zero. However, the braking force generated by this technology depends on the motor angular velocity. For this reason, it may be difficult to obtain the desired braking force, and the braking force is particularly weak at low angular velocities, and no braking force is generated at so-called zero speed. Therefore, when the angular velocity is low or zero speed, it may be problematic that a stable braking force cannot be generated.

[0008] For example, it is conceivable to apply the techniques of Patent Documents 2 and 3 to an automated guided vehicle driven by an electric motor as described in Patent Document 4. In this case, if force is applied when loading or unloading cargo, the automated guided vehicle may move, which may cause a problem of making it impossible to perform stable work.

[0009] An object of the present invention is to provide an electric motor device that is space-saving, low-cost, and capable of performing stable braking.

[0010] The electric motor device of the present invention is an axial gap type electric motor device comprising a housing, a stator supported by the housing, and a rotor rotatably supported by the housing and rotating axially opposite the stator, wherein the rotor includes a main shaft rotatably supported relative to the housing and the stator, and a field mechanism that rotates in sync with the main shaft and is slidable in the axial direction, and is provided with field mechanism regulating means that, when the field mechanism is slid in the axial direction, brings the field mechanism into contact with the housing or the stator, and brakes the rotation of the rotor and regulates the axial position of the field mechanism by the frictional force acting on the contact surface.

[0011] According to this configuration, the field mechanism regulating means brings the field mechanism into contact with the housing or the stator static system when the field mechanism is slid axially. The frictional force acting on the contact surfaces between the field mechanism and the static system brakes the rotor rotation and regulates the axial position of the field mechanism. This allows the rotor to be held accurately at any rotational position. In other words, stable braking is possible. By providing a field mechanism regulating means with the above-described frictional braking function between the field mechanism and the housing or the stator static system in an axial gap type electric motor device, a separate electromagnetic friction brake or the like is not required outside the motor, resulting in space savings and lower costs compared to conventional technologies that provide an electromagnetic friction brake or the like outside the motor, while also providing stable braking.

[0012] The motor may further include a control device that sets the stator in a desired current-carrying state, and the control device controls the stator between a restricted state in which rotation of the rotor is braked and the axial position of the field mechanism is restricted, and an unrestricted state in which rotation of the rotor and the axial position of the field mechanism are not restricted, by changing the current-carrying conditions of the stator. The current-carrying conditions are arbitrarily determined by design or the like, and are determined by, for example, determining appropriate conditions through testing and / or simulation. With this configuration, the control device can easily switch between the restricted state and the unrestricted state by changing the current-carrying conditions.

[0013] The field mechanism regulating means may have a braking portion provided in the field mechanism and a braked portion provided in the housing or the stator and in contact with the braking portion, and a friction material may be provided at a contact point between one or both of the braking portion and the braked portion. In this way, more stable braking can be achieved with a simple configuration by simply providing a friction material at a contact point between the braking portion or the braked portion.

[0014] The field mechanism regulating means may have a reaction spring that urges the field mechanism with a force in the axial direction, and the magnetic poles of the field mechanism and the reaction spring may be provided so that, with respect to a field magnetic force acting on the field mechanism by the magnetic poles of the field mechanism and a spring force acting on the field mechanism by the reaction spring, a field magnetic force difference, which is a difference in magnitude between the field magnetic force acting in the regulated state and the field magnetic force acting in the non-regulated state, is larger than a spring force difference, which is a difference in magnitude between the spring force acting in the regulated state and the spring force acting in the non-regulated state. In this case, it is possible to easily adjust the characteristics of the field magnetic force by the magnetic poles of the field mechanism and the spring force by the reaction spring.

[0015] The field mechanism regulating means may have a braking portion provided in the field mechanism and a braked portion provided in the housing or the stator and in contact with the braking portion, wherein the braking portion contacts the braked portion at a surface of the field mechanism facing the stator, and the braking portion and the braked portion may be located radially outward from the excitation coil of the stator and the magnetic poles of the rotor. When the braking portion and the braked portion are located radially outward from the excitation coil and the magnetic poles of the rotor in this way, a larger contact area can be ensured at the contact point, making it easier to ensure a desired frictional force, compared to when the braking portion, etc. are located radially inward from the excitation coil, etc.

[0016] The field mechanism regulating means includes a reaction spring that applies a force to the field mechanism in a direction in which the braking portion and the braked portion are separated from each other, i.e., in a direction in which the braking portion and the braked portion are separated from each other, and a separation limiting means that sets a limit position of the amount of movement of the field mechanism that can slide in the direction in which the braking portion and the braked portion are separated from each other, and when the field mechanism is in a state in which the sliding movement in the direction in which the braking portion and the braked portion are separated from each other is limited by the separation limiting means, the spring force that is applied to the field mechanism by the reaction spring to separate the braking portion and the braked portion is greater than the field magnetic force that is attracted to the stator by the magnetic poles of the field mechanism and brings the braking portion and the braked portion closer together, The magnetic poles of the field mechanism and the reaction spring may be arranged so that, when the field mechanism slides by a set amount or more in a direction in which the braking unit and the braked unit approach each other, from a state in which the separation limiting means restricts sliding of the field mechanism in a direction in which the braking unit and the braked unit move apart, the field magnetic force attracted to the stator by the magnetic poles of the field mechanism is greater than the spring force applied to the field mechanism by the reaction spring. The set amount is an amount determined arbitrarily by design or the like, for example, by determining an appropriate amount through testing and / or simulation. This configuration does not require power to maintain each of the restricted and unregulated states, and prevents undesired contact of the field mechanism with the stationary system on the opposite side of the braking unit when separating the braking unit from the braked unit, thereby enabling stable motor operation.

[0017] The field mechanism regulating means may have a braking portion provided in the field mechanism and a braked portion provided in the housing and in contact with the braking portion, and the braking portion may be configured so that a surface of the field mechanism facing away from the stator contacts the braked portion. In this case, a larger contact area can be ensured at the contact point than in a configuration in which the contact surface of the braking portion facing the stator contacts the braked portion.

[0018] The field mechanism regulating means includes a reaction spring that biases the field mechanism in a direction in which the braking portion and the braked portion approach each other, i.e., an axial force that moves them away from the stator, and a separation limiting means that sets a limit position of the amount of movement that the field mechanism can slide in the direction in which the braking portion and the braked portion move away from each other, and when the field mechanism is in a state in which sliding in the direction in which the braking portion and the braked portion move away from each other is restricted by the separation limiting means, a field magnetic force that is attracted to the stator by the magnetic poles of the field mechanism and that separates the braking portion and the braked portion is greater than a spring force that is biased by the reaction spring to bring the braking portion and the braked portion closer together, The magnetic poles of the field mechanism and the reaction spring may be provided so that, when the field mechanism has slid by a set amount or more in a direction in which the braking unit and the braked unit approach each other from a state in which the separation limiting means restricts sliding of the field mechanism in a direction in which the braking unit and the braked unit are separated, the spring force applied to the field mechanism by the reaction spring is greater than the field magnetic force attracted to the stator by the magnetic poles of the field mechanism. By setting the relationship between the field magnetic force and the spring force in this manner, electric power is not required to maintain each of the restricted state and the unrestricted state, and contact of the field mechanism with another stationary system, such as a housing on the opposite side of the braked unit, when the braking unit is separated from the braked unit can be prevented, thereby achieving stable motor operation.

[0019] The stators are arranged on both axial sides of the rotor and are of a double stator type in which both axial side surfaces of the rotor face the stator in the axial direction, and the field mechanism regulating means has a braking portion provided in the field mechanism and a braked portion provided on the housing or the stator and contacting the braking portion, and the braking portion is provided so that one axial side surface on either side of the field mechanism contacts the braked portion, and the braking portion and the braked portion are located radially outward of the excitation coil of the stator and the magnetic poles of the rotor, and the field mechanism regulating means may have a reaction spring that applies a force to the field mechanism in a direction that causes the braking portion and the braked portion to separate from each other, and a separation limiting means that sets a limit position for the amount of movement that the field mechanism can slide in the direction that causes the braking portion and the braked portion to separate from each other.

[0020] In this case, when the braking part separates from the braked part, the field mechanism is restricted by the separation limiting means from sliding further in the direction that separates the braking part and the braked part. When the braking part and the braked part are separated, i.e., in a non-braked state (unrestricted state), the axial gap between the rotor and one stator on the braked part side is set smaller than the axial gap between the rotor and the other stator. As a result, even when the excitation coils of both stators are driven under the same current conditions rather than independently, the electromagnetic force acting on the field mechanism is stronger on the one stator on the braked part side. This allows the sliding force of the field mechanism to be freely controlled.

[0021] The stators are arranged on both axial sides of the rotor and are of a double stator type in which both axial side surfaces of the rotor face the stator in the axial direction, the field mechanism regulating means has a braking portion provided in the field mechanism and a braked portion provided on the housing or the stator and contacts the braking portion, the braking portion is provided so that both axial side surfaces of the field mechanism can come into contact with the braked portion, and the braking portion and the braked portion are located radially outward of the stator excitation coil and the rotor magnetic poles, the stator excitation coil provided on one axial side of the rotor and the stator excitation coil provided on the other axial side can be driven under independent current conditions, and the control device may arbitrarily control which of the braking portions on both axial sides of the field mechanism to bring into contact with the braked portion to establish the regulated state.

[0022] With this configuration, the excitation coils of both stators can be driven with independent current conditions, allowing the field mechanism to apply an electromagnetic force that causes the stator to slide in any direction. This allows for arbitrary control of whether the braking unit contacts the braked unit on either stator side to enter a braking state (restricted state). Even if an abnormality occurs in a component on one of the braked units, the other braked unit can still be used, improving redundancy.

[0023] The braking unit may have a movable brake plate that is axially slidable relative to the field mechanism of the rotor and held circumferentially about the rotating shaft, and the braked unit may have a stationary brake plate that is axially slidable relative to the housing or the stator and held circumferentially about the rotating shaft, and the braking unit and the braked unit may have a multi-plate structure in which the field mechanism slides across the movable brake plate and the stationary brake plate to generate a braking force. In this case, when the field mechanism slides toward the braked unit during braking, the housing, movable brake plate, stationary brake plate, and field mechanism come into contact at opposing locations, and the resulting frictional force can generate a greater braking force.

[0024] The outer surface of the housing may be provided with a concave-convex portion, and at least a portion of the radial position where the field mechanism regulating means is provided may overlap with the radial position where the concave-convex portion is provided. In this case, the concave-convex portion increases the surface area of ​​the housing, and the motor can be configured in a space-saving manner without increasing the outermost diameter, thereby improving heat dissipation.

[0025] Any combination of at least two features disclosed in the claims and / or the specification and / or the drawings is included in the present invention. In particular, any combination of two or more of the claims is included in the present invention.

[0026] The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are merely for illustration and explanation, and should not be used to define the scope of the present invention, which is defined by the appended claims. In the accompanying drawings, the same reference numerals in multiple drawings indicate the same or corresponding parts.

[0027] 11 is a longitudinal sectional view of an electric motor device according to a first embodiment of the present invention. FIG. 12 is a perspective view of the electric motor device. FIG. 13 is a partially enlarged sectional view of the electric motor device in an unbraked state. FIG. 14 is a partially enlarged sectional view of the electric motor device in a braked state. FIG. 15 is a block diagram of a control device for the electric motor device. FIG. 16 is a longitudinal sectional view of an electric motor device according to a second embodiment of the present invention. FIG. 17 is a partially enlarged sectional view of the electric motor device in an unbraked state. FIG. 18 is a partially enlarged sectional view of the electric motor device in a braked state. FIG. 19 is a longitudinal sectional view of an electric motor device according to a third embodiment of the present invention. FIG. 19 is a partially enlarged sectional view of the electric motor device in an unbraked state. FIG. 19 is a partially enlarged sectional view of the electric motor device in a braked state. FIG. 19 is a longitudinal sectional view of an electric motor device according to a fourth embodiment of the present invention. FIG. 19 is a longitudinal sectional view of an electric motor device according to a fifth embodiment of the present invention. FIG. 19 is an enlarged sectional view of a braking section of the electric motor device. FIG. 19 is a sectional view taken along line XII-XII of FIG. 10. FIG. 19 is a diagram illustrating an example of design of the magnetic attraction force of a field mechanism and the spring force of a reaction spring. FIG. 20 is a diagram illustrating the relationship between the magnetic attraction force and the spring force in the configuration example of FIG. 5, which is configured so that the magnetic attraction force always exceeds the spring force. 9 is a diagram showing the relationship between magnetic attraction force and spring force when a function equivalent to that of a non-excitation actuated electromagnetic brake is provided.

[0028] [First Embodiment] An electric motor device according to an embodiment of the present invention will be described with reference to Figures 1 to 4. This electric motor device is mounted, for example, on a vehicle. <Overall Configuration of Electric Motor Device> As shown in Figure 1, electric motor device DM includes an axial gap motor 1 with a friction brake function and a control device 2 that controls motor 1. Motor 1 includes a housing 3, a stator 4, a rotor 5, bearings 6A and 6B, and a field mechanism regulating means 7. The stator 4 and rotor 5 are supported by the housing 3. The rotor 5 rotates opposite to the stator 4 in the axial direction C1 via an axial gap. The bearings 6A and 6B support the rotor 5 for free rotation. The field mechanism regulating means 7 brakes the rotation of the rotor 5 and regulates the axial position of a field mechanism 8 of the rotor 5.

[0029] <Rotor> The rotor 5 includes a main shaft 9 and a field mechanism 8. The main shaft 9 is rotatably supported relative to the housing 3 and the stator 4. The field mechanism 8 includes magnetic poles 10 that generate magnetic flux that contributes to the rotational torque of the rotor 5. The magnetic poles 10 are substantially parallel to the rotational axis direction C1 of the rotor 5 and face the stator 4 in the rotational axis direction C1. The rotational axis direction C1 is simply referred to as the "axial direction C1." The magnetic poles 10 are made of permanent magnets such as neodymium magnets, samarium-cobalt magnets, alnico magnets, and ferrite magnets. The field mechanism 8 holds the magnetic poles 10 and transmits the rotational torque generated by the magnetic poles 10 to the output side of the motor 1.

[0030] In the example shown in FIG. 1 , permanent magnets, which are magnetic poles 10, are fixed to a field mechanism 8, and a magnetic path is formed within the field mechanism 8 on the side opposite to the surface facing the stator 4, i.e., on the left side of FIG. 1 . For this reason, it is preferable that the field mechanism 8 uses a relatively inexpensive iron-based material with high magnetic permeability, such as carbon steel for mechanical structures (SC material), as a member for holding the magnetic poles 10, since this easily ensures the necessary mechanical strength while improving the magnetic properties of the magnetic poles 10. However, non-magnetic materials such as aluminum, resin, and some stainless steel (SUS material) may also be used for the field mechanism 8. For example, the magnetic poles 10 are formed of a plurality of magnets arranged so that their north and south poles alternate in the circumferential direction around the rotation axis.

[0031] The main shaft 9 is rotatably supported by bearings 6A and 6B. A plurality of bearings 6A and 6B (two in this example) are provided coaxially on the rotating shaft of the rotor 5, spaced at a predetermined interval. These bearings 6A and 6B support radial and axial loads. Rolling bearings such as deep groove ball bearings or angular contact ball bearings are used as the bearings 6A and 6B that support such radial and axial loads. An angular contact ball bearing may be used as one of the bearings 6A and 6B, and a deep groove ball bearing may be used as the other bearing.

[0032] In the configuration shown in FIG. 1 , the magnetic attraction force of the magnetic poles 10 of the rotor 5 acts in a direction that attracts the rotor 5 to the stator 4. Therefore, excluding the influence of external forces that may act from the output shaft, the bearing 6A located on the stator side is subject to a relatively larger axial load. Therefore, the stator-side bearing 6A may be configured with a bearing that is more durable than the other bearing 6B. Since larger bearings generally tend to have greater durability, in the example shown in FIG. 1 , the stator-side bearing 4A is configured with a larger bearing than the other bearing 6B. In this case, the other bearing 6B can be configured with a relatively smaller bearing, which is advantageous in that it allows for the electric motor device DM to be smaller and save space.

[0033] The field mechanism 8 is provided so as to rotate in synchronization with the main shaft 9 and to be slidable in the axial direction C1. Specifically, a fitting portion 11 between the main shaft 9 and the field mechanism 8 has a structure that allows sliding in the axial direction C1 and is held relatively in the circumferential direction so as to rotate in synchronization. A ball spline, for example, is used as the fitting portion 11.

[0034] <Stator> The stator 4 has a stator magnetic body 12 and an excitation coil 13. The excitation coil 13 forms magnetic poles that face the rotor 5 in the axial direction C1. For example, the stator magnetic body 12 and the excitation coil 13 are formed by providing the excitation coil 13 on one stator magnetic body 12. The stator magnetic body 12 is preferably made of a material that has relatively high magnetic permeability and relatively little eddy current loss due to high-frequency magnetic flux. If the stator magnetic body 12 is made of, for example, a powder magnetic core, an axial gap structure having magnetic poles in the axial direction C1 can be formed relatively inexpensively and easily. However, instead of a powder magnetic core, a laminated steel plate or an amorphous core can also be used. Alternatively, an air-core coil in which no stator magnetic body 12 exists in the region where the excitation coil 13 is provided may be used.

[0035] The excitation coils 13 may be concentrated windings, in which one excitation coil 13 forms one magnetic pole, or distributed windings, in which the excitation coils 13 are wound across multiple magnetic poles. The magnet wire forming the coils 13 is preferably made of a metal with relatively low electrical resistance, such as copper or aluminum. These coils 13 are connected to each other based on any specifications determined by design considerations, such as a predetermined connection method, such as a delta connection or star connection, a predetermined number of series or parallel connections, or a predetermined number of systems. A more robust structure can be achieved by providing the excitation coils 13 on the stator magnetic body 12 and then fixing them by varnish impregnation or insert molding. However, because this may increase manufacturing costs or weight, whether or not to implement such a robust structure should be determined appropriately according to design requirements.

[0036] <Housing> The housing 3 has first and second housings 3A and 3B divided in the axial direction C1, and mainly supports the bearings 6A and 6B and the stator 4. As shown in Fig. 2, the first and second housings 3A and 3B are formed from a material such as iron, aluminum, or resin. The first and second housings 3A and 3B are made of the same material, but different materials may also be used. As shown in Fig. 1, the first housing 3A is a divided body having a generally cylindrical shape with a bottom, which serves as the housing main body in this example.

[0037] The first housing 3A has a large-diameter portion 15 that houses the field mechanism 8 and supports a friction material 14 (described later), a medium-diameter portion 16 that houses the stator 4, and a small-diameter portion 17 that supports the outer ring of one of the bearings 6A. The large-diameter portion 15 has a larger diameter than the medium-diameter portion 16, and the small-diameter portion 17 has a smaller diameter than the medium-diameter portion 16. The second housing 3B in this example is a cover member 19 with a cylindrical portion 18 that serves as a motor cover, and the cylindrical portion 18 supports the outer ring of the other bearing 6B. The cylindrical portion 18 and the small-diameter portion 17 are concentrically arranged. The outer peripheral end of the cover member 19 of the second housing 3B is countersunk into the axial tip of the large-diameter portion 15, and the first and second housings 3A and 3B are fixed by adhesive, bolts, crimping, etc. Since the first housing 3A and the second housing 3B are fixed to each other in a countersunk state, the small diameter portion 17 of the first housing 3A and the cylindrical portion 18 of the second housing 3B are maintained concentric.

[0038] The axial tip end of the medium diameter portion 16 is connected to the axial base end of the large diameter portion 15 via an annular upright portion 20. The axial base end of the medium diameter portion 16 is connected to the axial base end of the small diameter portion 17 via an annular side plate 21 that forms the bottom surface that houses and supports the stator magnetic body 12 of the stator 4. One axial end of the small diameter portion 17 protrudes a predetermined axial length into the housing 3, and the other axial end of the small diameter portion 17 is closed by a circular plate 22. These elements of the first housing 3A are formed integrally. The term "integrally formed" means that the large diameter portion 15, medium diameter portion 16, small diameter portion 17, upright portion 20, side plate 21, and circular plate 22 are not formed by combining multiple elements but are formed as part or as the whole of a single object from a single material by, for example, forging or machining.

[0039] <Regarding the Field Mechanism Restricting Means> When the field mechanism 8 is slid in the axial direction C1, the field mechanism restricting means 7 brings the field mechanism 8 into contact with the housing 3 or the stator 4, and by the frictional force acting on the contact surface, brakes the rotation of the rotor 5 and restricts the axial position of the field mechanism 8. The field mechanism restricting means 7 has a braking portion 23 shown in Fig. 3A , a braked portion 24, friction material 14, a reaction force spring 25 shown in Fig. 1 , and separation limiting means 26B.

[0040] 3A , the braking portion 23 is provided on one axial side surface 8a of the field mechanism 8, and is located radially outward from the exciting coil 13 and the magnetic poles 10 of the rotor 5. The braked portion 24 is provided on the first housing 3A and comes into contact with the braking portion 23. The surface of the braking portion 23 facing the stator 4 in the field mechanism 8 comes into contact with the braked portion 24. The braked portion 24 is also located radially outward from the exciting coil 13 and the magnetic poles 10 of the rotor 5.

[0041] Friction material 14 is provided at a contact point of braked portion 24, which is either braking portion 23 or braked portion 24. For example, the friction material 14 may be made of a material similar to that used in known brake pads or brake linings. Friction material 14 faces a portion of one axial side surface 8a of field mechanism 8. When field mechanism 8 slides to the right in FIG. 3A , braking portion 23 comes into contact with friction material 14, as shown in FIG. 3B , and braking force is generated.

[0042] The friction material 14 may be fixed to the stator 4, which is the same stationary system as the housing 3, or may be provided on the field mechanism 8, which is the moving side. The friction material 14 may be provided at the contact points of both the stationary system, which is the housing 3 or the stator 4, and the field mechanism 8. Depending on the required braking force, the friction material 14 may not be provided, and the field mechanism 8 may be configured to be in direct contact with at least either the housing 3 or the stator 4. At least one of the housing 3 or the stator 4 and the field mechanism 8 may be made of a material with a relatively high and stable coefficient of friction.

[0043] In both cases where the friction material 14 is provided and where it is not provided, the braking portion 23 and the braked portion 24 generate a braking force by the frictional force generated by the contact pressure acting on the contact surface in a direction perpendicular to the circumferential direction of the rotation axis, without relying on the fitting of concave and convex shapes that would inhibit rotation. With this configuration, for example, when the braking portion 23 is in contact with the braked portion 24 while the rotor 5 is stationary, a braking force is applied at the rotational position where the braking portion 23 is in contact with the braked portion 24. This makes it possible to maintain a rotational position with high precision without any backlash or the like.

[0044] With this configuration, for example, when the rotor 5 is braked while rotating, the rotation can be slowed down and stopped relatively gently without causing any shock that could cause abnormalities in the motor, connecting members, etc. In this embodiment, an example is shown in which the braking portion 23 makes contact on a plane perpendicular to the rotation axis, but it can also have a tapered contact shape, for example.

[0045] 1 , a magnetic force that generates an axial thrust acts between the rotor 5 and the stator 4, and the strength of the magnetic force in the axial direction C1 can be changed as desired depending on the state of the magnetic poles of the stator 4. In other words, the control device 2 can change the axial thrust acting on the rotor 5 by changing the energization conditions of the excitation coil 13 of the stator 4. Therefore, the axial position of the field mechanism 8, which is slidable in the axial direction C1 on the rotor 5, can be controlled as desired.

[0046] Specifically, in a three-phase AC synchronous motor in which excitation coil 13 is driven by three-phase AC current, the attractive or repulsive force acting on field mechanism 8, and its magnitude, can be controlled by the sign and magnitude of the d-axis current. This makes it possible to arbitrarily change between moving field mechanism 8 to the stator 4 side, which is the right side in Figure 1, to bring braking portion 23 into contact and establish a braking state (restricted state), or moving field mechanism 8 to the opposite side to the above to place braking portion 23 away from braked portion 24 and establish a non-braking state (unrestricted state).

[0047] Additionally, by further changing the axial thrust in the braking state in which the braking portion 23 is in contact with the braked portion 24, it is possible to arbitrarily change the braking force generated in the braking portion 23 and the braked portion 24. That is, for example, the axial thrust can be applied so as to increase the contact pressure of the braking portion 23 in order to more firmly hold the rotation, or the axial thrust can be applied so as to decrease the contact pressure of the braking portion 23 in order to brake relatively gently.

[0048] <Reaction Spring> The reaction spring 25 applies a force in the axial direction C1 to the field mechanism 8. The reaction spring 25 of this embodiment applies a force in the axial direction C1 to the field mechanism 8, moving it away from the stator 4. In FIG. 1 , the reaction spring 25 in the form of a coil spring is in a compressed state, and applies a reaction force to the field mechanism 8 toward the left side in FIG. 1 .

[0049] Even when the exciting coil 13 of the stator 4 is in a non-energized state, the magnetic attractive force of the magnetic poles 10 of the field mechanism 8 acts as a force that moves the field mechanism 8 toward the stator 4, i.e., toward the right in FIG. 1 , where the braking portion 23 contacts the braked portion 24. For this reason, in order to maintain a non-braking state (non-restricted state) in which no braking force is generated during normal motor operation, it is necessary to manipulate the attractive force of the field mechanism 8. By providing the reaction force spring 25, the exciting coil current for maintaining a non-braking state in which no braking force is generated is either unnecessary or reduced. For this reason, it is preferable because it can suppress a decrease in efficiency during normal motor operation in which no braking force is generated.

[0050] However, it is also possible to control the axial position of the excitation mechanism 8 only by the excitation coil current, without providing the reaction spring 25. The reaction spring 25 can also be provided in a stretched state in the opposite direction to that shown in Figure 1. However, the configuration shown in Figure 1 makes it possible to utilize the space on the inner diameter side of the stator 4, and a configuration in which the spring force is applied in a compressed state is more suitable in that it is easier to support the reaction spring 25.

[0051] <Separation Limiting Means, etc.> Spacers 26A, 26B are interposed at both axial ends between the main shaft 9 and the bearings 6A, 6B. One axial spacer 26A supports a reaction spring 25 that applies an axial thrust to the field mechanism 8. When the field mechanism 8 moves to the left in FIG. 1 , i.e., away from the stator 4, the field mechanism 8 comes into contact with the other axial spacer 26B, restricting further movement in the axial direction C1. In other words, the spacer 26B functions as a separation limiting means that sets a limit to the amount of movement that the field mechanism 8 can slide in the axial direction C1 in the direction in which the braking portion 23 and the braked portion 24 separate, i.e., in the direction in which the field mechanism 8 moves away from the stator 4. This prevents the field mechanism 8 from coming into contact with other stationary systems, such as the housing on the opposite side of the braking portion 23, when the braking portion 23 is separated, ensuring stable motor operation.

[0052] <Heat Dissipation Structure> As shown in FIG. 2 , fin-shaped irregularities 27 are provided around the entire circumferential circumference of the outer surface of the first housing 3A. While FIG. 2 illustrates an example in which the heat dissipation structure is provided around the entire circumference of the first housing 3A for simplicity, the present invention is not limited to this example. For example, if a bolt fixing structure or the like is provided on the outer periphery of the housing 3, a region without a heat dissipation structure may be provided accordingly. The actual structure can be adjusted according to design considerations. In addition to the fin shape shown in FIG. 2 , pin-shaped irregularities may be used, and circumferential fins may be provided instead of axial fins as shown in FIG. 2 . The irregularities 27 may be provided on the outer surface of either or both of the first and second housings 3A and 3B.

[0053] As shown in Figure 1, at least a portion of the radial positions where the braking portion 23, braked portion 24, and friction material 14 are provided overlaps in the axial direction with the radial position where the uneven portion 27 is provided. Generally, the braking torque generated from a given pressing force increases the closer the braking portion 23 is located to the outer diameter, so it is preferable to position it as close to the outer diameter as possible. By providing uneven portion 27 with a heat dissipation shape as shown in Figure 1, it is possible to configure the motor in a space-saving manner without increasing its outermost diameter. In applications where the thermal load is not very high as a driving condition of motor 1, it is possible to omit providing such a heat dissipation shape.

[0054] <Sensors> For example, an angle sensor 28 shown in Fig. 4 may be provided to detect the rotation state of the rotor 5. As the angle sensor 28, for example, a resolver capable of detecting the rotation position with relatively high resolution, a magnetic encoder, or a magnetic switch that reacts when a predetermined rotor position is reached may be used. Alternatively, angle sensorless control may be used in which the position of the rotor 5 is estimated by the control device 2 from the energization state of the coil 13 shown in Fig. 1, without using the angle sensor 28.

[0055] As shown in FIG. 4, a current sensor 29 may be provided to detect the motor current. The current sensor 29 may be, for example, a sensor having a shunt resistor with a relatively small resistance value provided in the current path and an amplifier circuit that outputs voltage fluctuations of the shunt resistor, or a magnetic sensor provided near the current path. Alternatively, current sensorless control may be applied in which the control device 2 estimates the motor current from the motor voltage or the like without using a current sensor, or feedforward control may be applied in which the current is not estimated. For example, a temperature sensor may be provided to measure the temperature of the coil 13 shown in FIG. 1. Alternatively, a position sensor may be provided to measure the axial position of the field mechanism 8, i.e., the gap of the braking unit 23.

[0056] <Control Device> The control device 2 has a function of placing the stator 4 in a desired current-carrying state. By changing the current-carrying conditions of the stator 4, the control device 2 controls between a braking state (restricted state) in which the rotation of the rotor 5 is braked and the axial position of the field mechanism 8 is restricted, and a non-braking state (unrestricted state) in which the rotation of the rotor 5 and the axial position of the field mechanism 8 are not restricted. As shown in FIG. 4 , the control device 2 has a function of generating a desired torque to rotate the motor 1 based on a torque command TC. Furthermore, the control device 2 has a function of controlling the motor current based on a friction brake command BC, which is a friction brake operation request, to generate an electromagnetic force that slides the field mechanism 8 shown in FIG. 1 and causes the brake unit 23 to contact or separate. The control device 2 may be provided separately from the motor 1 and electrically connected thereto, or may be provided integrally with the motor 1.

[0057] 4, the control device 2 includes a motor controller 30, a current controller 31, a motor driver 32, and the current sensor 29. The motor controller 30 and the current controller 31 can be configured to be inexpensive and have high performance by using a general-purpose computing device such as a microcomputer, a field-programmable gate array (abbreviated as FPGA), an application specific integrated circuit (ASIC), or a digital signal processor (DSP).

[0058] The motor controller 30 has a function of deriving a target motor current for achieving a torque command TC and a friction brake command BC based on, for example, a torque command TC and a friction brake command BC from a host ECU or the like. The motor controller 30 includes a torque control unit 30a and an axial electromagnetic force control unit 30b. FIG. 4 illustrates only the basic structure of the control device 2, and details are omitted. However, the control device 2 has a function of performing servo control based on an angle command (position command) or an angular velocity command for a specific application, and may also have a function of deriving a motor torque for achieving these control requirements. In the example of FIG. 4 , the torque command TC and the friction brake command BC are each input to the motor controller 30. However, for example, a friction brake command BC linked or associated with the torque command TC may also be input to the motor controller 30.

[0059] The torque control unit 30a has a function of determining the motor current conditions for generating a desired motor torque. The motor current conditions may be calculated by estimating the motor angular velocity from the output of the angle sensor and using a look-up table (LUT) that stores correlations between motor torque and current at predetermined angular velocities that have been derived in advance based on analysis or experiment, or may be derived from mathematical expressions for the electromagnetic characteristics of the motor 1.

[0060] The axial electromagnetic force control unit 30b has a function for determining the motor current conditions for generating the desired friction braking force. This function may be a function for controlling the state transition for appropriately switching the braking unit 23 (FIG. 3A) between a braking state in which the braking unit 23 is in contact with the rotor and a non-braking state in which the braking unit 23 is in separation from the rotor, and a function for controlling the strength of the braking force in the braking state. These functions may be performed based on conditions determined in advance through experiments or analysis, or may be a function for calculating operating conditions based on the equation of motion of the field mechanism 8 (FIG. 3A) of the motor 1. When a configuration is adopted in which the braking state shown in FIGS. 13A to 13E can be maintained without excitation, the axial electromagnetic force control unit 30b may execute respective operating conditions depending on whether the friction braking force to be generated is a friction braking force due to excitation or a friction braking force without excitation. In this case, the friction braking command BC in FIG. 4 may be a protocol that can distinguish between an excitation and a non-excitation friction braking request.

[0061] In particular, if the rotor has surface magnet-type magnetic poles that do not have inductance saliency due to the rotation phase, the torque control unit 30a may have the function of determining the q-axis current, and the axial electromagnetic force control unit 30b may have the function of determining the d-axis current. In this case, each control unit can be configured simply, and the performance requirements of the computing hardware that implements the functions can be lowered, resulting in a low-cost configuration.

[0062] When the rotor 5 ( FIG. 3A ) has a structure with inductance saliency, or when advance angle control of the motor current is performed for high-speed rotation, the torque control unit 30 a and the axial electromagnetic force control unit 30 b may be implemented together as an LUT. For example, a three-dimensional LUT consisting of angular velocity coordinates, torque coordinates, and axial electromagnetic force coordinates may be stored in advance, and the torque control unit 30 a may determine the angular velocity coordinates and torque coordinates, and the axial electromagnetic force control unit 30 b may determine the axial electromagnetic force coordinates and acquire the target motor current from these coordinates.

[0063] The current controller 31 has a function of controlling the current flowing through the motor coil to follow the target motor current set by the motor controller 30. The motor driver 32 may be a drive circuit including a plurality of half-bridge circuits each configured with a switching element such as an FET.

[0064] Additionally, particularly when employing a double-stator motor as shown in FIG. 9 (described later), two systems of the current controller 31, motor driver 32, and current sensor 29 shown in FIG. 4 may be provided, each capable of independently controlling the motor current. In this case, the motor controller 30 may have the function of determining the current conditions for each of the two systems based on the torque command TC and the friction brake command BC. FIG. 4 merely illustrates the concept of the functions, and the block configuration of FIG. 4 does not limit the division of hardware and software. As long as the functions of FIG. 4 are not inconsistent, the integration and division of functions between hardware and software may be performed as appropriate based on design convenience. Desired functions may be added as appropriate based on the design requirements of the application, etc., as long as they do not impair the functionality of the present invention.

[0065] <Operation and Effect> In the electric motor device DM of Fig. 1 described above, the field mechanism regulating means 7 brings the field mechanism 8 into contact with the static system of the housing 3 or the stator 4 when the field mechanism 8 is slid in the axial direction C1. The frictional force acting on the contact surfaces between the field mechanism 8 and the static system brakes the rotation of the rotor 5 and regulates the axial position of the field mechanism 8. This makes it possible to hold the rotor 5 in a rotational position with high precision. In other words, stable braking can be achieved.

[0066] In an axial gap type electric motor device DM, by providing a field mechanism regulating means 7 having a braking function using friction force as described above between the field mechanism 8 and a stationary system such as the housing 3, a separate electromagnetic friction brake or the like is not required outside the motor, thereby achieving space savings and lower costs compared to conventional techniques that provide an electromagnetic friction brake or the like outside the motor, and enabling stable braking. When the braking portion 23 and the braked portion 24 are located radially outward of the exciting coil 13 and the magnetic poles 10 of the rotor 5, it is possible to ensure a larger contact area at the contact points and easily ensure the desired friction force, compared to when the braking portion or the like is located radially inward of the exciting coil or the like.

[0067] <Regarding Other Embodiments> In the following description, parts corresponding to matters previously described in each embodiment are assigned the same reference numerals, and duplicated description will be omitted. When only part of the configuration is described, the other parts of the configuration are the same as those in the previously described embodiment unless otherwise specified. The same configuration produces the same effects. It is possible to combine not only the parts specifically described in each embodiment, but also parts of the embodiments together, provided that there is no particular problem with the combination.

[0068] [Second embodiment: FIGS. 5 to 6B] Figure 5 shows an example in which the braked portion 24 and the friction material 14 are provided in the second housing 3B, and the braking portion 23 and the braked portion 24 are configured on the opposite axial side from the previously described embodiment. The braking portion 23 contacts the braked portion 24 at the surface of the field mechanism 8 facing away from the stator 4. The relationship between the state of the braking portion 23, the magnetic attraction force of the magnetic poles 10 of the rotor 5, and the spring force exerted by the reaction spring 25 is opposite to that of the previously described embodiment. That is, as shown in Figure 6B, the spring force acts to bring the braking portion 23 into contact with the friction material 14 of the braked portion 24, and as shown in Figure 6A, the magnetic attraction force of the magnetic poles 10 of the rotor 5 acts to separate the braking portion 23 from the braked portion 24.

[0069] As shown in Figure 5, when the excitation mechanism 8 moves in the axial direction C1 to the right in Figure 5, which is a direction toward the stator 4, i.e., in a direction that separates the braking portion 23 from the braked portion 24, the excitation mechanism 8 comes into contact with the spacer 26A and is restricted from further movement in the axial direction C1. In other words, the spacer 26A functions as a separation limiting means that sets a limit position for the amount of movement that the excitation mechanism 8 can slide in the direction that separates the braking portion 23 and the non-braked portion 24, i.e., in the direction toward the stator 4. This prevents the excitation mechanism 8 from coming into contact with other stationary systems, such as the stator on the opposite side of the braking portion 23, when separating the braking portion 23, thereby ensuring stable motor operation.

[0070] [Third Embodiment: Double Stator Type One-Sided Braking, FIGS. 7 to 8B] The electric motor device DM of FIG. 7 is a double stator type in which the stator 4 is disposed on both axial sides of the rotor 5, and both axial side surfaces of the rotor 5 face the stator 4 in the axial direction C1. The braking portion 23 is provided such that one axial side surface of one of the field mechanism 8 contacts the braked portion 24, and the braking portion 23 and the braked portion 24 are located radially outward of the exciting coil 13 of the stator 4 and the magnetic poles 10 of the rotor 5. The field mechanism restricting means 7 has a reaction force spring 25 that applies a force in the axial direction C1 to the field mechanism 8 to move away from the braked portion 24, and a spacer 26B that serves as separation limiting means that sets a limit position in the axial direction C1 of the amount of movement in which the field mechanism 8 can slide in the direction away from the braked portion 24.

[0071] Specifically, the rotor 5 faces the stator 4A on one side of the rotational axis C1, that is, the right side in Fig. 7, and faces the stator 4B on the other side, that is, the left side in Fig. 7. Friction material 14 is fixed to the first housing 3A on the stator 4A side, and the field mechanism 8 slides to the right in Fig. 7 to face the stator 4A, thereby forming a braking unit 23 that comes into contact with the friction material 14 and generates a braking force, as shown in Fig. 8B. As shown in Fig. 7, a reaction spring 25 is provided between the spacer 26A and the field mechanism 8, and a spring force is applied in the direction in which the field mechanism 8 moves away from the stator 4A, i.e., in the direction in which the braking unit 23 moves away.

[0072] When braking portion 23 separates as shown in Figure 8A, field mechanism 8 in Figure 7 comes into contact with spacer 26B, restricting further movement toward stator 4B. With sliding of field mechanism 8 restricted by the separation restriction means, the gap between rotor 5 and stator 4A is set smaller than the gap between rotor 5 and stator 4B. In other words, within the sliding range of excitation mechanism 5 of rotor 5, stator 4A on the side where friction material 14 is provided is always closer.

[0073] By doing this, even when the excitation coils 13 of the stators 4A and 4B are driven under the same current conditions rather than independently, the electromagnetic force acting on the field mechanism 8 will be stronger in stator 4A, making it possible to freely control the sliding force of field mechanism 8. Specifically, for example, when the field mechanisms 8 of both stators 4A and 4B generate repulsive electromagnetic forces, the sum of these forces acts as an electromagnetic force that causes field mechanism 8 to slide in a direction away from the closer stator 4A.

[0074] Conversely, when both stators 4A and 4B generate electromagnetic forces that attract field mechanism 8, the sum of these forces acts to cause field mechanism 8 to slide in a direction toward the closer stator 4A. When control device 2 is configured so that excitation coils 13 of stators 4A and 4B can be driven under independent current conditions, an electromagnetic force can be applied to cause field mechanism 8 to slide in any direction regardless of where field mechanism 8 is located between stators 4A and 4B, so it is not necessary to configure field mechanism 8 so that it always approaches stator 4A as described above.

[0075] The configuration shown in the figure can also be reversed. That is, a friction material can be provided on the housing 3B on the stator 4B side, a reaction spring can be provided between spacer 26B and field mechanism 8, and field mechanism 8 can be positioned so that it is always close to stator 4B within the sliding range. Also, friction material 14 can be fixed to the stator or the like instead of to housing 3, or it can be fixed to field mechanism 8. Also, without providing reaction spring 25, field mechanism 8 can be slid only by the electromagnetic force generated by excitation coil 13 of stator 4.

[0076] A configuration may be adopted in which a braking portion 23 is provided on the stator 4B side, and a reaction spring 25 provided between the field mechanism 8 and spacer 26A acts as a pressing force on the braking portion 23, or conversely, a configuration in which a reaction spring 25 provided between the field mechanism 8 and spacer 26B acts as a pressing force on the braking portion 23 on the stator 4A side. In this case, if the exciting coils 13 of the stators 4A and 4B cannot be set to independent current conditions, the field mechanism 8 is always provided closer to the stator on the opposite side to the braking portion 23. Furthermore, the spacer on the opposite side to the braking portion 23 and the field mechanism 8 come into contact with each other when the braking portion 23 is in a non-braking state where it is spaced apart, thereby restricting the sliding of the field mechanism 8, and various members are provided between the spacer on the braking portion 23 side and the field mechanism 8 so that a gap exists between the field mechanism 8 and the braking portion 23 side that allows the field mechanism 8 to slide sufficiently until the braking portion 23 comes into contact.

[0077] [Fourth embodiment: double stator type double-sided braking, FIG. 9] The electric motor device DM of FIG. 9 is a double stator type, and the braking portion 23 is provided so that both axial side surfaces of the field mechanism 8 can come into contact with the braked portion 24, and the braking portion 23 and the braked portion 24 are located radially outward of the excitation coil 13 of the stator 4 and the magnetic poles 10 of the rotor 5. The excitation coil 13 of the stator 4A provided on one axial side of the rotor 5 and the excitation coil 13 of the stator 4B provided on the other axial side can be driven under independent current conditions. The control device 2 arbitrarily controls which of the braking portions 23, 23 on both axial sides of the field mechanism 8 should come into contact with the braked portion 24 to enter a braking state (restricted state).

[0078] Specifically, friction materials 14 are provided in the first and second housings 3A and 3B on both sides of the field mechanism 8, forming braking units 23 on both axial sides of the field mechanism 8. The control device 2 is configured so that the excitation coils 13 of the stators 4A and 4B can be driven under independent current conditions. Therefore, an electromagnetic force can be applied to cause the field mechanism 8 to slide in any direction. Therefore, the control device 2 can arbitrarily control which of the friction materials 14A and 14B the braking unit 23 contacts to establish a braking state. Reaction springs 25A and 25B are provided between the field mechanism 8 and spacers 26A and 26B on both sides of the field mechanism 8, respectively. The resultant force of the reaction springs 25A and 25B acts as a spring force that attempts to return the field mechanism 8 to a substantially intermediate position between the stators 4A and 4B, regardless of whether the field mechanism 8 slides toward the stators 4A or 4B.

[0079] With this electric motor device DM, for example, even if an abnormality occurs in one of the friction materials 26A, 26B, the other friction material can still be used, improving redundancy. When the rotor 5 is continuously braking from a rotating state, for example, alternating use of the friction materials 26A, 26B can reduce thermal load. In this case, for example, the control device 2 may store the extent to which the braking unit 23 is used based on the angular velocity of the rotor 5 and the electromagnetic force generated in the axial direction C1, and may be provided with a function to change which of the friction materials 26A, 26B to use based on that level. Alternatively, sensors may be provided to measure the temperature, wear, and other conditions of the friction materials 26A, 26B, and a function to change which of the friction materials 26A, 26B to use based on those conditions.

[0080] 10 to 12] In electric motor device DM of Fig. 10, braking portion 23 has movable braking plates 33 that are slidable in the axial direction C1 relative to field mechanism 8 of rotor 5 and are held in the circumferential direction of the rotating shaft, and braked portion 24 has stationary braking plates 34 that are slidable in the axial direction C1 relative to housing 3 or stator 4 and are held in the circumferential direction of the rotating shaft. Braking portion 23 and braked portion 24 have a multi-plate structure in which field mechanism 8 slides across movable braking plate 33 and stationary braking plate 34 to generate a braking force. Specifically, braking portion 23 and braked portion 24 are provided on the outer periphery of field mechanism 8.

[0081] 11 is an enlarged cross-sectional view of the braking portion 23 and the braked portion 24. Friction material 14 is provided in the first housing 3A, and a movable brake plate 33 is provided opposite the friction material 14 so as to be slidable in the axial direction C1 relative to the field mechanism 8 but not rotatable relative thereto (so as to hold the field mechanism 8 in the circumferential direction of the rotating shaft). A stationary brake plate 34 is provided opposite the movable brake plate 33 so as to be slidable in the axial direction C1 relative to the first housing 3A but not rotatable relative thereto (so as to hold the field mechanism 8 in the circumferential direction of the rotating shaft). Furthermore, the stationary brake plate 34 faces the field mechanism 8.

[0082] When the braking portion 23 is in the separated state, the movable-side brake plate 33 is pressed by the movable-side reaction spring 35 against a movable-side brake plate stopper 36 fixed to the field mechanism 8, and the stationary-side brake plate 34 is pressed by the stationary-side reaction spring 37 against a stationary-side brake plate stopper 38 fixed to the first housing 3A, and they are held with a gap maintained between them and the opposing members. During braking, when the field mechanism 8 moves to the right in Figure 11, the first housing 3A, movable-side brake plate 33, stationary-side brake plate 34, and field mechanism 8 come into contact at their opposing locations, and the resulting friction generates a braking force.

[0083] It is also possible to adopt a structure that does not include the movable-side reaction spring 35, stationary-side reaction spring 37, movable-side brake plate stopper 36, and stationary-side brake plate stopper 38. In that case, although there is a disadvantage that the movable-side brake plate 33 and the stationary-side brake plate 34 come into contact during motor operation, resulting in a slight decrease in efficiency, there is an advantage that the structure can be constructed relatively inexpensively with a small number of parts. Although Fig. 11 shows an example in which one movable-side brake plate 33 and one stationary-side brake plate 34 are provided, two or more movable-side brake plates 33 and two or more stationary-side brake plates 34 may be used to form a multi-layered multi-plate structure.

[0084] Figure 12 shows a cross section taken along line XII-XII in Figure 10 as an example of the structure of the stationary brake plate 34 and the movable brake plate 33. As shown in Figure 12, the stationary brake plate 34 fits into a groove 3Aa provided on the circumference of the first housing 3A and is held so as to be non-rotatable relative to the first housing 3A but movable in the axial direction, except for a gap δ1 at the fitting portion. The movable brake plate 33 fits into a groove 8b provided on the circumference of the field mechanism 8 and is held so as to be non-rotatable relative to the field mechanism 8 but movable in the axial direction, except for a gap δ2 at the fitting portion.

[0085] This shape is merely one example, and any shape that can hold the components together and prevent relative rotation is applicable. For example, a partially or entirely flattened shape such as a two-face width, a D-cut, or a polygonal shape may be used, or a splined fit may be used. The multi-plate structure of the braking unit 23 and the braked unit 24 of this embodiment can also be used in a structure in which the braking unit is configured on the axially opposite side from the field mechanism as shown in FIG. 5, and in a double stator structure as shown in FIGS. 7 and 9.

[0086] <Design Example of Magnetic Attractive Force of Field Mechanism and Spring Force of Reaction Spring: Figures 13A to 13E> Figures 13A to 13E show design examples of the relationship between the magnetic attractive force of the magnetic poles 10 of the field mechanism 8 and the spring force exerted by the reaction spring 25 in the structures shown in Figures 1, 5, 7, 9, 10, etc. Figures 13A to 13E merely illustrate the magnitude relationship of the forces and the image of how the forces change depending on the position of the field mechanism, and are not intended to limit the exact ratios or gradients of change. Throughout Figures 13A to 13E, the horizontal axis represents the axial position of the field mechanism, and the vertical axis represents the axial thrust acting on the field mechanism when the field mechanism is located at that axial position. In this case, to clearly show the magnitude relationship between the magnetic attractive force and the spring force as absolute values, the magnetic attractive force and the spring force are shown with the same symbol on the vertical axis, even though their actual force directions are opposite to each other. The axial position of the field mechanism is defined as the positive direction on the horizontal axis to the right in FIGS.

[0087] Fig. 13A shows an example of the relationship between magnetic attraction force and spring force in the configuration example of Fig. 1. In Fig. 13A, when the field mechanism is restricted by the separation limiting means from sliding in the direction in which the braking part and the braked part move apart, i.e., in the axial direction away from the stator, the spring force urged by the reaction spring to the field mechanism is greater than the field magnetic force attracted to the stator by the magnetic poles of the field mechanism. When the field mechanism slides by more than a set amount from the above state in the direction in which the braking part and the braked part move closer to each other, i.e., in the direction in which they move closer to the stator, the magnetic poles of the field mechanism and the reaction spring are arranged so that the field magnetic force attracted to the stator by the magnetic poles of the field mechanism is greater than the spring force urged to the field mechanism by the reaction spring.

[0088] Specifically, let fm1(x) be the magnetic attractive force of the magnetic poles of the field mechanism at a given field mechanism position x, and let fs1(x) be the spring force of the reaction spring. fm1(x) is positive when it acts as a force pulling the field mechanism toward the stator, while fs1(x) is positive when it acts as a force pulling the field mechanism away from the stator. At field mechanism position gr1, where the braking unit is separated from the braked unit and is in an unbraked state, allowing normal motor operation, fm1(gr1) < fs1(gr1), and the braked unit is located on the stator side. Therefore, unless an external axial thrust is applied to the field mechanism, the field mechanism remains in an unbraked (uncontrolled) state. In this case, if the stator excitation coil generates an axial electromagnetic force greater than fs1(gr1) - fm1(gr1) as an attractive force toward the stator, the field mechanism will slide toward the stator. As a specific example, this electromagnetic force can be exerted by passing a d-axis current that generates an excitation magnetic flux component generally in the same direction as the magnetic poles of the field mechanism.

[0089] When the field mechanism moves further toward the stator than gc1, a predetermined distance from the non-braking (non-restricted) position gr1, the relationship fm1(x) > fs1(x) (x > gc1) holds, and the field mechanism naturally moves toward the stator. When the field mechanism is in gb1, where the braking section is in contact with the braking section, a force of fm1(gb1) - fs1(gb1) is applied to the braking section, maintaining a braking force even without current flowing through the stator excitation coil. At this time, if the stator generates an axial electromagnetic force (an axial electromagnetic force acting on the field mechanism due to the excitation magnetic flux component oriented approximately in the same direction as the magnetic poles of the field mechanism), the strength of the braking force can be adjusted as desired by varying the direction and magnitude of this electromagnetic force.

[0090] When separating the braking part and the braked part from a state in which the field mechanism is at gb1, if an axial electromagnetic force exceeding fm1(gb1) - fs1(gb1) is generated as a repulsive force in the direction opposite the stator, the field mechanism will slide toward the side opposite the stator and the braking part will separate. As a specific example, this electromagnetic force can be applied by passing a d-axis current that generates an excitation magnetic flux component in the direction opposite to the magnetic poles of the field mechanism.

[0091] Adopting a configuration of magnetic poles and reaction springs in the field mechanism that results in such characteristics of magnetic attraction force and spring force is advantageous in that it reduces power consumption because it does not require axial electromagnetic force from the stator to maintain either of the states in which the field mechanism is positioned in gb1, which is the braking state, or in gr1, which is the non-braking state.

[0092] FIG. 13B illustrates the relationship between the magnetic attractive force and the spring force in the configuration example of FIG. 1 , differing from FIG. 13A in that the magnetic attractive force always exceeds the spring force. The magnetic attractive force of the magnetic poles of the field mechanism at a given field mechanism position x is represented by fm2(x), and the spring force of the reaction spring is represented by fs2(x). The directions of these forces are the same as in FIG. 13A . In FIG. 13B , at a field mechanism position gr2 where the braking unit is separated and in a non-braking state, allowing normal motor operation, the stator excitation coil generates an axial electromagnetic force exceeding fm2(gr2) - fs2(gr2) as a repulsive force toward the side opposite the stator to maintain the field mechanism in a non-braking state. This electromagnetic force can be exerted, for example, by passing a d-axis current that generates an excitation magnetic flux component in the direction opposite the magnetic poles of the field mechanism.

[0093] When the repulsive force due to the axial electromagnetic force of the stator falls below fm2(gr2) - fs2(gr2), or when an axial electromagnetic force of a polarity that attracts the stator is generated, the field mechanism slides toward the stator, reaching gb2 where the braking unit contacts, entering a braking state (restricted state). When the field mechanism is in gb2, a force of fm2(gb2) - fs2(gb2) is applied to the braking unit, maintaining a braking force even when no current is applied to the stator excitation coil. When an axial electromagnetic force is generated by the stator at this time, the strength of the braking force can be adjusted as desired by changing the direction and magnitude of the electromagnetic force.

[0094] When the field mechanism is in position gb2 and the brake unit is to be separated, an axial electromagnetic force exceeding fm2(gb2) - fs2(gb2) is generated as a repulsive force toward the opposite side of the stator, causing the field mechanism to slide toward the opposite side of the stator and the brake unit to separate. This electromagnetic force can be applied, for example, by passing a d-axis current that generates an excitation magnetic flux component in the opposite direction to the magnetic poles of the field mechanism. Even when a reaction spring is not used, the behavior of the field mechanism at each position is similar to that shown in FIG. 13A. In other words, FIG. 13B shows a configuration in which a reaction spring is used to reduce the current that generates the axial electromagnetic force required to maintain the non-braked state.

[0095] With the configuration of Figure 13B, for example, if an abnormality occurs in the motor or control device and power supply fails, the field mechanism transitions to a braking state due to magnetic attraction, thereby providing functionality similar to that of a general non-excitation activated electromagnetic brake, making it suitable for use in applications that configure such redundant systems. However, in order to perform normal motor operation in a non-braking state, it becomes necessary to continue to supply current that generates an axial electromagnetic force to maintain the non-braking state. The structural examples of Figures 7 and 10 can also employ configurations that have the same tendencies as those of Figures 13A to 13B.

[0096] Fig. 13C shows an example of the relationship between magnetic attraction force and spring force in the configuration example of Fig. 5. In Fig. 13C, when the separation limiting means restricts sliding of the field mechanism in the direction in which the braking part and the braked part move away from each other, i.e., in the direction toward the stator, the field magnetic force attracted to the stator by the magnetic poles of the field mechanism is greater than the spring force urged by the reaction spring to the field mechanism. The magnetic poles of the field mechanism and the reaction spring are arranged so that when the braking part and the braked part slide from the above state in the direction in which they move toward each other, i.e., in the direction away from the stator, by more than a set amount, the spring force urged to the field mechanism by the reaction spring is greater than the field magnetic force attracted to the stator by the magnetic poles of the field mechanism.

[0097] Specifically, let fm3(x) be the magnetic attractive force of the magnetic poles of the field mechanism at a given field mechanism position x, and let fs3(x) be the spring force of the reaction spring, with the directions of these forces being the same as in Figure 13A. At field mechanism position gr3, where the braking unit and the braked unit are separated from each other and in an unbraked state, allowing normal motor operation, fm3(gr3) > fs3(gr3). Since the braking unit is located on the opposite side of the stator from the field mechanism, the field mechanism remains in an unbraked state. In this case, if the stator excitation coil generates an axial electromagnetic force greater than fm3(gr3) - fs3(gr3) as a repulsive force toward the opposite side of the stator, the field mechanism will slide toward the opposite side of the stator.

[0098] When the field mechanism moves further away from the stator than gc3, a predetermined distance away from the stator from the non-braking position gr3, fm3(x) < fs3(x) (x < gc3) occurs, and the field mechanism naturally moves away from the stator. When the field mechanism is at gb3, where the braking section is in contact with the braking section, a force of fs3(gb3) - fm3(gb3) is applied to the braking section, maintaining a braking force even when no current is applied to the stator excitation coil. At this time, if an axial electromagnetic force is generated by the stator, the strength of the braking force can be adjusted as desired by changing the direction and magnitude of this electromagnetic force.

[0099] When the braking unit is separated from the field mechanism when it is in gb3, an axial electromagnetic force exceeding fs3(gb3) - fm3(gb3) is generated as an attractive force toward the stator, causing the field mechanism to slide toward the stator and separating the braking unit and the braked unit. Overall, Figure 13C shows an example in which the braking unit and braked unit are arranged on the opposite side of the field mechanism from Figure 13A, and the magnetic attractive force of the magnetic poles of the field mechanism and the spring force of the reaction spring have the opposite relationship to Figure 13A with respect to the transition between the braking state and the non-braking state, and the advantages of employing this characteristic are the same as those in Figure 13A.

[0100] Figure 13D shows an example where a function equivalent to a non-excitation activated electromagnetic brake is provided, which differs from the example shown in Figure 13C. The magnetic attraction force of the magnetic poles of the field mechanism at a given field mechanism position x is fm4(x), and the spring force of the reaction spring is fs4(x), with the directions of each force being the same as in Figure 13C. The spring force fs4 always exceeds fm4 in the range gb4 ≤ x ≤ gr4. At field mechanism position gr4, where the braking part and the braked part are separated from each other in an unbraked state and normal motor operation is possible, the stator excitation coil generates an axial electromagnetic force exceeding fs4(gr4) - fm4(gr4) as an attraction force toward the stator in order to maintain the field mechanism in an unbraked state.

[0101] When the attractive force of the axial electromagnetic force of the stator falls below fs4(gb4) - fm4(gb4), or when an axial electromagnetic force of a polarity that repels the stator is generated, the field mechanism slides away from the stator and reaches gb4, where the braking unit contacts, entering a braking state. When the field mechanism is in gb4, the force fs4(gb4) - fm4(gb4) is applied to the braking unit, maintaining a braking force even when the stator excitation coil is not energized. If an axial electromagnetic force is generated by the stator at this time, the strength of the braking force can be adjusted as desired by changing the direction and magnitude of this electromagnetic force. When the field mechanism is in gb4 and the braking unit is separated, an axial electromagnetic force greater than fs4(gb4) - fm4(gb4) is generated as an attractive force toward the stator, causing the field mechanism to slide toward the stator, separating the braking unit from the braked unit.

[0102] 13E shows an example of the relationship between the magnetic attractive force and the spring force in the configuration example of FIG. Let fmA5(x) be the magnetic attractive force of the magnetic poles of the field mechanism, fsA5(x) be the spring force of the reaction spring, and let fmB5(x) be the magnetic attractive force of the magnetic poles of the field mechanism and fsB5(x) be the spring force of the reaction spring at a field mechanism position x that is less than gr5. fmA5(x) is positive in the direction acting as a force that moves the field mechanism closer to stator 4A ( FIG. 9 ), fsA5(x) is positive in the direction acting as a force that moves the field mechanism away from stator 4A ( FIG. 9 ), fmB5(x) is positive in the direction acting as a force that moves the field mechanism closer to stator 4B ( FIG. 9 ), and fsB5(x) is positive in the direction acting as a force that moves the field mechanism away from stator 4B ( FIG. 9 ).

[0103] When the field mechanism is located between grB5 and grA5, fsA5(x) > fmA5(x) on the stator 4A ( FIG. 9 ) side of the intermediate gr5, and fsB5(x) > fmB5(x) on the stator 4B ( FIG. 9 ) side, resulting in a force pushing the excitation mechanism back toward gr5. Therefore, unless an external axial thrust is applied, the field mechanism is positioned at gr5, where both the magnetic attractive force and the spring force are approximately zero and in equilibrium. This state is maintained as a non-braking state with the braking unit separated. However, in reality, the equilibrium positions of the magnetic attractive force and the spring force may not coincide due to dimensional tolerances of components, etc. However, this diagram illustrates the design concept, and designs that include such error factors are not excluded from this embodiment.

[0104] When an axial electromagnetic force toward stator 4A exceeding fsA5(x) - fmA5(x) or an axial electromagnetic force toward stator 4B exceeding fsB5(x) - fmB5(x) is applied from a state gr5 in which the field mechanism is not braked and allows normal motor operation, the field mechanism slides toward either stator 4A ( FIG. 9 ) or stator 4B ( FIG. 9 ). This axial electromagnetic force may be caused by, for example, an attractive or repulsive force of either stator 4A or 4B ( FIG. 9 ), or it may be caused by a resultant force of an attractive or repulsive force by stator 4A ( FIG. 9 ) and an axial electromagnetic force by stator 4B ( FIG. 9 ) that is opposite to that of stator 4A ( FIG. 9 ).

[0105] When the field mechanism moves further toward stator 4A (FIG. 9) than the predetermined distance gcA5 from gr5 toward stator 4A (FIG. 9), fmA5(x) > fsA5(x) (x > gcA5) holds, and the field mechanism naturally shifts toward stator 4A (FIG. 9). When the field mechanism is in gbA5, where the braking section on the stator 4A (FIG. 9) side is in contact, a force of fmA5(gbA5) - fsA5(gbA5) is applied to the braking section, maintaining a braking force even when no current is applied to the stator excitation coil. In this case, if an axial electromagnetic force is generated by either or both of stators 4A and 4B (FIG. 9), the strength of the braking force can be adjusted as desired by changing the direction and magnitude of this electromagnetic force.

[0106] Similarly, when the field mechanism moves further toward stator 4B (FIG. 9) than gcB5, which is a predetermined distance from gr5 toward stator 4B (FIG. 9), fmB5(x) > fsB5(x) (x < gcB5) is satisfied, and the field mechanism naturally shifts toward stator 4B (FIG. 9). When the field mechanism is at gbB5, where the braking section on the stator 4B (FIG. 9) side is in contact, a force of fmB5(gbB5) - fsB5(gbB5) is applied to the braking section, maintaining a braking force, even without current flowing through the stator excitation coil. If a reaction spring is not used in FIG. 9, the braking and non-braking states are all controlled by the electromagnetic forces of stators 4A and 4B (FIG. 9). That is, when maintaining a non-braking state, the axial position of the field mechanism is controlled to the vicinity of gr5 in FIG. 13E by the axial electromagnetic force of stators 4A, 4B (FIG. 9), and when entering a braking state, an axial electromagnetic force is generated in one of the braking parts to cause the field mechanism to slide.

[0107] 13A to 13E are as follows: The magnetic poles of the field mechanism and the reaction spring are arranged so that, with respect to the field magnetic force acting on the field mechanism by the magnetic poles of the field mechanism and the spring force acting on the field mechanism by the reaction spring, the field magnetic force difference, which is the difference in magnitude between the field magnetic force acting in the braking state, which is the restricted state, and the field magnetic force acting in the non-braking state, which is the non-restricted state, is greater than the spring force difference, which is the difference in magnitude between the spring force acting in the braking state and the spring force acting in the non-braking state.

[0108] To achieve the characteristics shown in Figures 13A to 13E, it is preferable to use a spring structure such as a coil spring with a relatively long extension / contraction stroke and to install the reaction spring in a state where it is deformed to some extent from its natural length. This allows the change in magnetic attraction force due to changes in the gap between the field mechanism and the stator to be greater, while the change in spring force due to reaction spring deformation to be smaller. This makes it easy to adjust the characteristics shown in Figures 13A to 13E. Specifically, in the example of Figure 13A, the change in magnetic attraction force fm1 when the field mechanism position changes between gr1 and gb1 is greater than the change in spring force fs1, thereby achieving the characteristics shown in Figure 13A.

[0109] <Others> The field mechanism 8 of Fig. 1 etc. may have a structure in which the yoke portion is divided so that an iron-based material or electromagnetic steel plate with a relatively high magnetic permeability is used only in the portion in contact with the permanent magnet, and the non-magnetic material described above is used in the other portion. The magnetic poles 10 may be fixed to the field mechanism 8 by adhesive or the like, for example. In the case where the field mechanism 8 is at least partially made of resin, the magnetic poles 10 may be fixed to the field mechanism 8 by insert molding or the like. Alternatively, the magnetic poles 10 may be directly molded into the field mechanism 8 using a material such as a mixture of magnetic powder and resin.

[0110] The magnetic poles 10 may be configured in a Halbach array, for example, with a magnet interposed between the north and south poles to form a magnetic pole that is approximately perpendicular to the north and south poles. They may also be magnetized to the desired number of poles using a ring-shaped magnet in the field magnet section. Embedded magnet type magnetic poles may also be used, with a substantially flat core formed of laminated electromagnetic steel sheets or a powder magnetic core as part of the field mechanism 8, and a magnet inserted into a slit that penetrates the core in the direction of the rotation axis.

[0111] The bearings 6A, 6B on both axial sides may be the same size. In this case, it is possible to obtain the effect of reducing costs by reducing the number of parts used. Alternatively, for example, one of the bearings 6A on the stator side may be an angular contact ball bearing with excellent axial load capacity, and the other bearing 6B may be a deep groove ball bearing. Any configuration can be selected for the bearings 6A, 6B depending on the application, sales conditions, etc.

[0112] The braked portion 24 may also be provided on the stator 4. The fitting portion between the main shaft 9 and the field mechanism 8 may be, for example, a spline fitting that allows sliding contact in the axial direction C1, or a fitting structure in which a part or the whole is fitted with a flattened shape such as a two-face width, D-cut, or polygonal shape. The stator 4 may have a split core shape in which the stator magnetic body 12 is divided into a predetermined pattern according to the magnetic poles, and each divided body is provided with an excitation coil 13 and fixed together. The electric motor device DM may also be used for applications other than vehicles, such as industrial machinery and drones.

[0113] As described above, the preferred embodiment has been described with reference to the drawings, but various additions, modifications, and deletions can be made without departing from the spirit of the present invention. Therefore, such additions, modifications, and deletions are also included in the scope of the present invention.

[0114] DESCRIPTION OF SYMBOLS 1...motor 2...control device 3...housing 4...stator 5...rotor 7...field mechanism restricting means 8...field mechanism 9...main shaft 14...friction material 23...braking portion 24...brake receiving portion 25...reaction spring 26A, 26B...spacer (separation restricting means) 27...uneven portion 33...movable side brake plate 34...stationary side brake plate DM...electric motor device

Claims

1. An axial gap type electric motor device comprising a housing, a stator supported by the housing, and a rotor rotatably supported by the housing and rotating axially opposite the stator, wherein the rotor includes a main shaft rotatably supported relative to the housing and the stator, and a field mechanism that rotates in sync with the main shaft and is slidable in the axial direction, and the electric motor device is equipped with field mechanism regulation means that, when the field mechanism is slid in the axial direction, brings the field mechanism into contact with the housing or the stator, and brakes the rotation of the rotor and regulates the axial position of the field mechanism by the frictional force acting on the contact surface.

2. An electric motor device according to claim 1, further comprising a control device that sets the stator in any current-carrying state, and the control device changes the current-carrying conditions of the stator to control between a restricted state in which the rotation of the rotor is braked and the axial position of the field mechanism is restricted, and an unrestricted state in which the rotation of the rotor and the axial position of the field mechanism are not restricted.

3. An electric motor device as described in claim 2, wherein the field mechanism regulating means has a braking part provided in the field mechanism and a braked part provided in the housing or the stator and in contact with the braking part, and wherein friction material is provided at the contact points of either or both of the braking part and the braked part.

4. An electric motor device as claimed in claim 2 or claim 3, wherein the field mechanism regulating means has a reaction spring that applies an axial force to the field mechanism, and the magnetic poles of the field mechanism and the reaction spring are arranged so that, with respect to the field magnetic force acting on the field mechanism by the magnetic poles of the field mechanism and the spring force acting on the field mechanism by the reaction spring, the field magnetic force difference, which is the difference in magnitude between the field magnetic force acting in the regulated state and the field magnetic force acting in the non-regulated state, is greater than the spring force difference, which is the difference in magnitude between the spring force acting in the regulated state and the spring force acting in the non-regulated state.

5. An electric motor device as claimed in claim 1 or 2, wherein the field mechanism regulating means has a braking part provided in the field mechanism and a braked part provided in the housing or the stator and in contact with the braking part, the braking part has a surface of the field mechanism facing the stator that contacts the braked part, and the braking part and the braked part are located radially outward of the excitation coil of the stator and the magnetic poles of the rotor.

6. In the electric motor device described in claim 5, the field mechanism restricting means comprises a reaction spring that applies a force to the field mechanism in a direction that separates the braking portion and the braked portion, and separation limiting means that sets a limit position at which the field mechanism can slide in the direction that separates the braking portion and the braked portion, and when the field mechanism is restricted from sliding in the direction that separates the braking portion and the braked portion by the separation limiting means, the spring force applied to the field mechanism by the reaction spring is greater than the field magnetic force attracted to the stator by the magnetic poles of the field mechanism, an electric motor device in which the magnetic poles of the field mechanism and the reaction spring are provided so that, when the braking portion and the braked portion have slid in a direction approaching each other by a set amount or more from a state in which sliding of the field mechanism is restricted by the separation restriction means, the field magnetic force attracted to the stator by the magnetic poles of the field mechanism is greater than the spring force applied to the field mechanism by the reaction spring.

7. An electric motor device as claimed in claim 1 or claim 2, wherein the field mechanism regulating means has a braking part provided in the field mechanism and a braked part provided in the housing and in contact with the braking part, and the braking part is an electric motor device in which the surface of the field mechanism facing away from the stator comes into contact with the braked part.

8. In the electric motor device described in claim 7, the field mechanism restricting means comprises a reaction spring that applies a force to the field mechanism in a direction that brings the braking portion and the braked portion closer to each other, and a separation limiting means that sets a limit position at which the field mechanism can slide in a direction that separates the braking portion and the braked portion, and when the field mechanism is restricted from sliding in a direction that separates the braking portion and the braked portion by the separation limiting means, the field magnetic force attracted to the stator by the magnetic poles of the field mechanism is greater than the spring force applied to the field mechanism by the reaction spring, an electric motor device in which the magnetic poles of the field mechanism and the reaction spring are arranged so that, when the braking portion and the braked portion have slid closer to each other by a set amount or more from a state in which sliding of the field mechanism is restricted by the separation restriction means, the spring force applied to the field mechanism by the reaction spring is greater than the field magnetic force attracted to the stator by the magnetic poles of the field mechanism.

9. An electric motor device according to claim 1 or 2, wherein the stators are arranged on both axial sides of the rotor and are of a double stator type with both axial side surfaces of the rotor facing the stator in the axial direction, and the field mechanism regulating means has a braking portion provided on the field mechanism and a braked portion provided on the housing or the stator and contacting the braking portion, the braking portion being arranged so that one axial side surface of either one of the field mechanism contacts the braked portion, and the braking portion and the braked portion are positioned radially outward of the excitation coil of the stator and the magnetic poles of the rotor, and the field mechanism regulating means has a reaction spring that applies a force to the field mechanism in a direction that causes the braking portion and the braked portion to separate apart, and separation limiting means that sets a limit position for the amount of movement that the field mechanism can slide in the direction that causes the braking portion and the braked portion to separate apart.

10. An electric motor device according to claim 2, wherein the stators are arranged on both axial sides of the rotor and are of a double stator type with both axial side surfaces of the rotor facing the stator in the axial direction, and the field mechanism regulating means has a braking part provided on the field mechanism and a braked part provided on the housing or the stator and contacting the braking part, and the braking part is arranged so that both axial side surfaces of the field mechanism can come into contact with the braked part, and the braking part and the braked part are located radially outward of the stator excitation coil and the rotor magnetic poles, and the stator excitation coil provided on one axial side of the rotor and the stator excitation coil provided on the other axial side can be driven under independent current conditions, and the control device is an electric motor device which arbitrarily controls which of the braking parts on both axial sides of the field mechanism should come into contact with the braked part to establish the regulated state.

11. An electric motor device as described in claim 3, wherein the braking section has a movable braking plate that is axially slidable relative to the rotor's field mechanism and is held circumferentially about the rotating shaft, and the braked section has a stationary braking plate that is axially slidable relative to the housing or stator and is held circumferentially about the rotating shaft, and the braking section and the braked section have a multi-plate structure in which the field mechanism slides between the movable braking plate and the stationary braking plate to generate braking force.

12. An electric motor device according to claim 1 or claim 2, wherein an uneven portion is provided on the outer surface of the housing, and at least a portion of the radial position where the field mechanism regulating means is provided overlaps with the radial position where the uneven portion is provided in the axial direction.

Images