JPWO2012067178A1 - Electromagnetic actuator - Google Patents

Abstract

Provided is an electromagnetic actuator having high performance that has a large attractive force and linear attractive force characteristics even if it is small. The electromagnetic actuator includes first and second fixed iron cores 12 and 14 that are arranged to face each other via a predetermined gap 10 in the direction of the axis O, and a movable iron core that is arranged to be movable along the axis O in the vicinity of the gap 10. 16 and an electromagnetic actuator comprising a coil 18 that applies a magnetic field to the two fixed iron cores 12 and 14 and the movable iron core 16 to form a magnetic path therein and drives the movable iron core 16 toward the first fixed iron core 12. The movable iron core 16 has a magnetic flux guiding part 32 that extends in the axial direction along the surface of the second fixed iron core 14 and a magnetic flux acting part 34 that crosses the gap 10.

Description

  The present invention relates to an electromagnetic actuator used for driving various members by reciprocating a shaft with a solenoid.

  Such an electromagnetic actuator uses an electromagnetic force acting between a fixed iron core and a movable iron core arranged along a magnetic path formed by a solenoid coil as an attractive force. In order to secure the attractive force and required stroke at the time of initial movement, the end of the fixed iron core is cylindrical, the movable iron core is placed inside it, and the movable iron core is sucked into the fixed iron core by the magnetic force acting between the ends. Structure is adopted.

  By the way, with the recent expansion of the field of use, a larger suction force and a longer operation stroke are required along with downsizing and cost reduction which are essentially contradictory to these. Further, a characteristic that the suction force is constant in the stroke range (linear suction force characteristic) is also required as an important factor for facilitating the position control of the driven member.

  In order to meet these performance requirements, it is necessary to design the configuration of the magnetic path formed by the fixed iron core and the movable iron core based on the relative movement between the two. As such an attempt, in Patent Document 1, a truncated cone surface (inclined surface) having a shape corresponding to each other is formed at opposing ends of the suction-side fixed iron core and the movable iron core. This is because in the case of cylindrical bodies that are basic shapes, suction force works when the movable iron core is approaching from the outside, but once sucked, the cylindrical surfaces face each other, so the axial component force is It has been made in view of the fact that it is greatly reduced. In this technique, since a predetermined axial component force acts between the inclined surfaces even after the suction, it is said that a flat characteristic can be obtained by suppressing a decrease in the suction force with respect to the stroke movement distance.

  On the other hand, Patent Document 2 is a further improvement of the technique of Patent Document 1, in which an inclined surface is formed as an auxiliary suction surface while leaving a cylindrical surface at a portion where the fixed iron core and the movable iron core face each other. In this technique, a suction force between the cylindrical surfaces acts in the first half of the stroke movement, and a suction force acts between the inclined surfaces in the second half. Therefore, it is said that a flat attraction force characteristic can be obtained while avoiding the disadvantage that the attraction efficiency with respect to the energization amount of the coil in the technique of Patent Document 1 is avoided.

  Furthermore, in patent document 3, as shown to Fig.6 (a), the peripheral wall-shaped processus | protrusion 102 whose front end side becomes thin is formed in the end surface of the fixed iron core 100 by the side of suction, and magnetic flux is concentrated on this front-end | tip part. Thus, it is possible to avoid the disadvantage that the efficiency of sucking the movable iron core 106 when the coil 104 is energized particularly during the initial movement is low.

JP-A-4-282804 JP 2000-277327 A JP 2006-153283 A

  However, it is difficult for all of the above-described conventional techniques to satisfy the performance required for recent electromagnetic actuators. That is, in the technique of Patent Document 1, since the suction efficiency with respect to the energization amount of the coil is low as described above, it is disadvantageous to obtain a large suction force, and a gap (air gap) between the movable iron core and the suction side fixed iron core. When the pressure is large, that is, the suction force is low at the initial movement, the responsiveness is poor, and a flat suction force characteristic cannot be obtained.

  Further, in the technique of Patent Document 2, the suction efficiency is increased by compensating for the lowering of the suction force in the second half of the stroke with the suction force between the inclined surfaces, and a flat suction force characteristic is ensured. However, since these inclined surfaces are formed in a narrow space inside the cylindrical fixed iron core and the projected sectional area in the axial direction is small, it is not possible to sufficiently compensate for the reduction in suction force. Therefore, it has been difficult to obtain a large suction force and a flat suction force characteristic. Furthermore, in the technique of Patent Document 3, although an improvement in the suction force at the initial stroke is achieved, it is not sufficient.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electromagnetic actuator having high performance that has a large attractive force and linear attractive force characteristics even if it is small.

  In order to achieve the object, the electromagnetic actuator according to claim 1 includes a first and a second fixed iron cores arranged opposite to each other with a predetermined gap in the axial direction, and the vicinity of the gap along the axis. A movable iron core that is movably disposed, and a coil that applies a magnetic field to the two fixed iron cores and the movable iron core to form a magnetic path therein and drives the movable iron core toward the first fixed iron core. In the electromagnetic actuator provided, the movable iron core includes a magnetic flux guiding portion extending in an axial direction along a surface of the second fixed iron core, and a magnetic flux acting portion crossing the gap.

  In the first aspect of the invention, since the magnetic flux acting part of the movable iron core crosses the gap between the first and second fixed iron cores, the magnetic flux passing through the gap does not leak to the other. The electromagnetic force is generated through the magnetic flux acting part, so that the efficiency of generating the attractive force is improved and a large attractive force can be obtained. In addition, the first and second fixed iron cores face the magnetic flux acting part from the opposite sides, so that it is possible to secure a wide delivery surface by eliminating mutual interference, and the attraction force generation efficiency is also improved in this respect. . Furthermore, it is easy to change the shape of the magnetic flux line transfer surface, and it is easy to achieve the purpose such as adjusting the balance of magnetic flux and force.

  According to a second aspect of the present invention, in the electromagnetic actuator according to the first aspect, a tapered concave portion or a convex portion is formed on an end surface facing the gap of the first fixed iron core, and the magnetic flux action is performed. The part has a shape along the end face.

  In the invention according to claim 2, the tapered concave portion and the convex portion are opposed to each other in the fixed iron core and the movable iron core, and the suction force is distributed to the axial component and the radial component according to the taper angle. Since a certain amount of axial suction force is maintained even when the relative movement is performed, a change in the suction force with respect to the stroke can be suppressed, and a flat suction force characteristic can be obtained.

  An electromagnetic actuator according to a third aspect is the invention according to the first or second aspect, wherein the magnetic flux guiding portion is disposed along an outer peripheral surface of the second fixed iron core. .

  In the invention according to claim 3, it is not necessary to provide a space for accommodating the magnetic flux guiding portion inside the second fixed iron core, and the manufacturing cost is reduced by omitting complicated processing, and the movable iron core is made thin. The cup shape reduces weight, opens the way to production by press molding from plate-like members, and reduces the load by reducing the spring load to return to the initial position, and the load itself by reducing friction This is also effective in improving vibration resistance (preventing chattering).

  According to a fourth aspect of the present invention, in the electromagnetic actuator according to any one of the first to third aspects, the movable iron core is inserted through the first fixed iron core and the first fixed iron core. It is attached to the front-end | tip of the shaft supported by the bearing by at least 2 points | pieces.

  In the invention according to claim 4, the structure for supporting the shaft is simplified, and the clearance on the suction side, that is, the radial clearance between the first fixed iron core and the movable iron core can be reduced, The suction force can be improved in a wide range from the initial stroke to the middle stroke.

  ADVANTAGE OF THE INVENTION According to this invention, the electromagnetic actuator which produces | generates a big attraction force can be provided in small size and low cost by forming a magnetic path with few magnetic flux leaks in a fixed iron core and a movable iron core.

It is the schematic which shows the electromagnetic actuator which concerns on 1st Embodiment of this invention. It is the schematic which shows the electromagnetic actuator which concerns on the modification of 1st Embodiment of this invention. It is a magnetic flux diagram which shows the effect | action of the electromagnetic actuator of FIG. 1A. It is a magnetic flux diagram which shows the effect | action of the electromagnetic actuator of FIG. 1A. It is a magnetic flux diagram which shows the effect | action of the electromagnetic actuator of FIG. 1A. It is a graph which shows the effect of the electromagnetic actuator which concerns on embodiment of this invention compared with a prior art example. It is a graph which shows the effect of the electromagnetic actuator which concerns on the 1st Embodiment of this invention compared with a modification. It is the schematic which shows the electromagnetic actuator which concerns on 2nd Embodiment of this invention. It is a magnetic flux line diagram which shows the effect | action of the electromagnetic actuator of FIG. It is a magnetic flux line diagram which shows the effect | action of the electromagnetic actuator of FIG. It is a magnetic flux line diagram which shows the effect | action of the electromagnetic actuator of FIG. It is a schematic sectional drawing which shows an example of the conventional electromagnetic actuator. It is a magnetic flux line diagram which shows the effect | action of the electromagnetic actuator of FIG. It is a magnetic flux line diagram which shows the effect | action of the electromagnetic actuator of FIG. It is a magnetic flux line diagram which shows the effect | action of the electromagnetic actuator of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The electromagnetic actuator according to the first embodiment of the present invention shown in FIG. 1A is, for example, for operating a fuel lever of a diesel internal combustion engine in a stop direction to automatically stop the engine, or for a four-wheel manual operation. It is used for automatically performing reverse select lock in a transmission vehicle. FIG. 1A (b) is a simplified model used when performing a magnetic path analysis by a computer as will be described later.

  The electromagnetic actuator includes a first fixed iron core 12 and a second fixed iron core 14 that are arranged to face each other via a predetermined gap 10 in the direction of the axis O, and is movable along the axis O in the vicinity of the gap 10. The movable iron core 16 disposed, the two fixed iron cores 12 and 14, and a coil 18 that applies a magnetic field to the movable iron core 16 to form a magnetic path therethrough and moves the movable iron core 16 along the axis O are provided. Yes. Each of these members is basically rotationally symmetric, that is, has a circular cross section and is accommodated in a cylindrical housing 20.

  The two fixed iron cores 12 and 14 have hook-like portions 22 and 24 on the upper and lower end surfaces, respectively, and the magnetic field generated by the coil 18 is guided through the hook-like portions 22 and 24 to enter the gap 10. Forms a high-density magnetic flux. When the coil 18 is energized, an attractive force is generated from the two fixed iron cores 12 and 14 to the movable iron core 16, but as will be described later, the first fixed iron core 12 has a larger attractive force so that it is movable when energized. The iron core 16 moves toward the first fixed iron core 12. That is, the first fixed iron core 12 mainly performs a suction action, and the second fixed iron core 14 performs a magnetic flux induction action. A through hole 26 is formed in the first fixed core 12 along the axis O, and a shaft 30 is movably installed through two bearings 28, 28. It is fixed to. The outer diameter of the second fixed iron core 14 is smaller than that of the first fixed iron core 12, so that a space for arranging a magnetic flux guiding portion 32 of the movable iron core 16 described later is provided between the inner surface of the coil 18. Is formed.

  The movable iron core 16 has a cup shape (bottomed cylindrical shape) from a cylindrical magnetic flux guiding portion 32 extending along the axis O direction and a magnetic flux acting portion 34 extending in a direction intersecting the axis O so as to cross the gap 10. The tip of the shaft 30 is inserted and fixed in a through hole 36 formed in the center of the magnetic flux acting part 34. The inner surface of the magnetic flux guiding portion 32 faces the outer surface of the second fixed iron core 14 with a small gap, and the direction in which most of the magnetic flux between the second fixed iron core 14 and the movable iron core 16 is substantially perpendicular to these surfaces. That is, it passes here along a direction perpendicular to the axis O. Therefore, almost no force in the direction of the axis O is generated between the second fixed iron core 14 and the movable iron core 16. On the other hand, the first fixed iron core 12 faces only the magnetic flux acting portion 34 of the movable iron core 16, and the magnetic flux generated here has a component in the direction of the axis O, so that an attractive force in the direction of the axis O is generated. Therefore, a suction force toward the first fixed iron core 12 acts on the movable iron core 16.

  In this example, the end surface of the first fixed iron core 12 on the gap 10 side is formed with a concave portion 40 that is a tapered surface 38 whose side surface is widened toward the opening, and is a portion of the movable iron core 16 facing this. A certain magnetic flux acting part 34 is also formed in a shape corresponding to the concave part 40. That is, the magnetic flux acting part 34 in this example includes a first acting part 44 having a tapered surface 42 corresponding to the tapered surface 38 of the recessed part 40 and a second acting part having a flat surface 48 corresponding to the bottom surface 46 of the recessed part 40. 50. With such a configuration, as will be described in detail later, the change in the suction force in the direction of the axis O with respect to the displacement of the movable iron core 16 is reduced, the change in the suction force in the stroke range is suppressed, and the linear suction force characteristics are obtained. Can be obtained.

In this example, since the magnetic flux guiding portion 32 is arranged on the outer peripheral side of the second fixed iron core 14, it is not necessary to process the second fixed iron core 14 into a cylindrical shape as compared with the case where it is arranged inside, Manufacturing cost can be reduced. Since the shaft 30 is supported in a cantilevered manner by a pair of bearings 28, 28 provided in the through hole 26 of the first fixed iron core 12, the bearing space is saved. Further, since both the pair of bearings 28 and 28 are installed in the through hole 26 of the first fixed iron core 12, that is, both the two bearings 28 and 28 are installed in the single through hole 26. Since the axial deviation between the two bearings 28 is reduced, the radial clearance (gap) between the movable iron core 16 fixed to the shaft 30 and the first fixed iron core 12 can be reduced. As a result, the suction force can be improved. In this case, the radial clearance between the movable iron core 16 and the second fixed iron core 14 needs to be slightly widened, but the suction force can be improved even in consideration thereof.
Note that the shaft 30 may be inserted into the second fixed iron core 14 depending on the situation in which it is used, or depending on the case, a bearing installed on both the fixed iron cores 12 and 14 as in the conventional case. You may make it support. As a modification of the first embodiment shown in FIG. 1A, FIG. 1B shows a case where a pair of bearings 28 and 28 are installed on both fixed iron cores 12 and 14.
Further, as in the conventional example shown in FIG. 6, the magnetic flux guiding portion 32 may be arranged on the inner peripheral side of the second fixed iron core 14. In that case, the magnetic flux acting part 34 crosses the gap 10 by projecting outside the magnetic flux guiding part 32.

  Next, the operation of the electromagnetic actuator configured as described above will be described with reference to FIGS. 2A to 2C which are magnetic path analysis results by CAE (Computer Aided Engineering). The conventional electromagnetic actuator shown in FIG. 6 (a) is modeled as shown in FIG. 6 (b), with the electromagnetic actuator of the present embodiment being aligned with conditions such as iron core weight, applied current, and coil 18 specifications. The analysis results of the objects are shown in FIGS. 7A to 7B as comparative examples.

  2A and 7A show magnetic flux diagrams in the initial state, and the distance (air gap) between the flat surfaces of the movable iron core 16 and the first fixed iron core 12 is 2.8 mm. 2B and 7B show a state where the air gap is 1.4 mm in the middle of the stroke, and FIGS. 2C and 7C show a state where the air gap is 0.4 mm at the end of the stroke. In the initial state, the magnetic flux density between the tip of the peripheral wall of the first fixed iron core 12 and the tip of the movable iron core 16 is large, and the force acting on this part is mainly responsible for the attraction action. Then, the magnetic flux between the flat surfaces increases, and the attractive force acting at this portion occupies a predetermined ratio, and in the final state, the attractive force acting between the flat surfaces is the main.

The above is a matter common to this embodiment and the comparative example, but the difference is described below. First, in this embodiment, the movable iron core 16 is disposed so as to cross the gap 10, and almost all of the magnetic flux generated between the first and second stationary iron cores 14 passes through the movable iron core 16. Therefore, the magnetic flux utilization efficiency is very high. On the other hand, in the configuration of the prior art, there is a region where the fixed iron cores directly face each other in the gap 10, and a magnetic flux that does not contribute to attraction is generated here, resulting in a decrease in efficiency. Therefore, in this embodiment, even if it is the same magnitude | size and energization amount compared with the past, a big attraction | suction force is obtained. FIG. 3A shows the relationship between the air gap (stroke) and the attractive force obtained by the magnetic path analysis, and it can be seen that the present embodiment obtains a larger attractive force particularly in the initial range of the stroke.
FIG. 3B is a graph showing the comparison between the first embodiment of FIG. 1A and the modification of FIG. 1B, and shows the relationship between the air gap (stroke) obtained by magnetic path analysis and the attractive force. . As can be seen from the figure, when the pair of bearings 28 and 28 are both installed in the through hole 26 of the first fixed core 12, the pair of bearings 28 and 28 are connected to the first and second fixed cores 12. It can be seen that a large suction force of about 10% is obtained in a wide range from the initial stroke (air gap 2.8 mm) to the middle period (near air gap 1.4 mm), compared with the case where it is installed at 14.

  Next, in this embodiment, as a result of the movable iron core 16 being arranged so as to cross the gap 10, the first fixed iron core 12 and the second fixed iron core 14 face the opposite surfaces of the movable iron core 16. It will be. Therefore, the first fixed iron core 12 and the second fixed iron core 14 can use a wide area for transferring magnetic flux lines without having the same surface, and the attraction force is also improved in this respect. In addition, since there is no interference between the magnetic flux line transfer surfaces in this way, it is easy to change the shape of these surfaces, and in this embodiment, the first action part having a tapered surface is formed in the magnetic flux action part 34. Thus, the balance between the radial and axial magnetic fluxes and forces is adjusted, and as a result, as shown in FIG. 3A, a flat attractive force characteristic is obtained. In addition, since the movable iron core 16 of the said embodiment is a comparatively thin cup shape, it can manufacture by press-molding a plate-shaped member besides the usual cutting process. Moreover, in this embodiment, the movable iron core 16 is cup-shaped, and when this moves, it is thought that an inner pressure increases and becomes resistance. In that case, an air vent hole may be provided at an appropriate location.

  FIG. 4A is an electromagnetic actuator according to the second embodiment of the present invention, and FIG. 4B is a simplified model thereof. In this embodiment, a convex portion 52 is provided on the surface of the first fixed iron core 12 on the gap 10 side instead of the concave portion. A concave portion 54 having a shape corresponding to the convex portion 52 is formed on the facing surface of the movable iron core 16. Similar to the previous embodiment, the side surfaces of the convex portion 52 and the concave portion 54 are tapered surfaces 56 and 58 of a predetermined angle. Magnetic flux diagrams showing the operation of this embodiment are shown in FIGS. 5A to 5C. The relationship between the air gap (stroke) and the suction force is shown in FIG. 3A.

  As can be seen from these figures, the electromagnetic actuator of this embodiment also showed high magnetic flux utilization efficiency similar to that of the first embodiment, and showed a larger suction force and a flat stroke-attraction force characteristic than the conventional example. . In this main electromagnetic actuator, the attraction force at the initial stage of movement with the weakest attraction force was improved by about 20% in the first embodiment and about 10% in the second embodiment compared to the conventional example. . Therefore, if it is desired to obtain a suction force equivalent to that of the conventional example, the weight of the movable iron core can be reduced by about 40%. Such weight reduction of the movable iron core leads to advantages such as improved vibration resistance and reduced load on the return spring.

O axis 10 gap 12 first fixed iron core 14 second fixed iron core 16 movable iron core 18 coil 32 magnetic flux guiding part 34 magnetic flux acting part

Claims (4)

First and second fixed iron cores arranged opposite to each other via a predetermined gap in the axial direction, a movable iron core movably arranged along the axis in the vicinity of the gap, the two fixed iron cores and the movable iron core In an electromagnetic actuator comprising a coil that applies a magnetic field to an iron core to form a magnetic path in them, and drives the movable iron core toward the first fixed iron core,
The movable iron core includes a magnetic flux guiding portion that extends in an axial direction along a surface of the second fixed iron core, and a magnetic flux acting portion that crosses the gap.   The end face of the first fixed iron core facing the gap is formed with a tapered recess or protrusion, and the magnetic flux acting part has a shape along the end face. Item 2. The electromagnetic actuator according to Item 1.   The electromagnetic actuator according to claim 1, wherein the magnetic flux guiding portion is disposed along an outer peripheral surface of the second fixed iron core.   The movable iron core is attached to a tip of a shaft that is inserted through the first fixed iron core and supported by bearings at at least two points inside the first fixed iron core. 4. The electromagnetic actuator according to any one of 3 above.

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