JP2015103781A - Electromagnetic actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce variations in response resulting in variations in magnetic force of a permanent magnet, in an electromagnetic actuator that is used in a valve lift adjustment device for an internal combustion engine and actuates two regulating pins.SOLUTION: In an electromagnetic actuator 401, magnetic clearances are formed between permanent magnets 521, 522 and adapters 551, 552 via non-magnetic spacers 541, 542 according to variations in magnetic force of permanent magnets 521, 522. The electromagnetic actuator 401 makes adjustment such that magnetic attraction forces acting on plungers 651, 652 are in a desirable range. Thus, magnetic attraction force acting on the first and the second plungers 651, 652 in the same product can be made uniform. Variations in the magnetic attraction forces of the electromagnetic actuator 401 due to the manufacturing lot of the permanent magnets 521, 522 can be reduced. Accordingly, variations in response in the electromagnetic actuator 401 can be reduced.

Description

  The present invention relates to an electromagnetic actuator that is applied to a valve lift adjusting device for an internal combustion engine and switches a slider position by advancing a regulating pin to engage with an engaging groove.

  2. Description of the Related Art Conventionally, in a valve lift adjustment device that adjusts the lift amount of an intake valve or an exhaust valve of an internal combustion engine, the position of a slider provided so as to be movable relative to the camshaft in an axial direction while rotating together with the camshaft is known. It has been. Also, as a means for switching the position of the slider, either one of the two restricting pins is selectively operated according to the moving direction of the slider, and the tip of the restricting pin is fitted in the engaging groove formed in the slider An electromagnetic actuator is known.

  For example, in the electromagnetic actuator described in Patent Document 1, two permanent magnets that attract the plunger in the backward direction are fixed to the stationary part so that the magnetic poles are opposite to each other. Then, by switching the energizing direction of the coil, a magnetic flux in the opposite direction is generated with respect to one of the two permanent magnets to reduce the attractive force, and the regulating pin on the side where the attractive force of the permanent magnet is reduced is applied to the spring biasing force. Operate in the forward direction.

JP 2013-239538 A

In the electromagnetic actuator of Patent Document 1, from the “dead time” that is the time from the start of energization to the coil to the start of start of the restriction pin, and the time from the start of energization to the coil until the restriction pin reaches the full stroke The “responsiveness” corresponding to the time obtained by subtracting the predetermined expected control time is determined by the magnetic force of the permanent magnet and the biasing force of the spring.
By the way, in the actual product, there is a variation in the magnetic force between the individual permanent magnets, so the magnet attractive force acting on the plunger varies between the two regulating pins in the same product or between the individual products. Variations in the responsiveness of the electromagnetic actuator occur.

  The present invention has been created in view of the above-described problems, and an object thereof is an electromagnetic actuator that is applied to a valve lift adjusting device of an internal combustion engine and operates two restriction pins, and is caused by variation in magnetic force of a permanent magnet. It is an object of the present invention to provide an electromagnetic actuator that reduces variations in responsiveness.

  The present invention is applied to a valve lift adjustment device for an internal combustion engine, and operates in a forward direction by a biasing force of a spring by reducing the attractive force of a permanent magnet by energizing a coil with respect to either one of two regulation pins. The electromagnetic actuator includes a magnetism collecting member provided at an end portion of the permanent magnet on the plunger side and a magnetic path member provided on the opposite side of the plunger of the permanent magnet. A magnetic clearance is formed between the magnet and the magnetic flux collecting member or between the permanent magnet and the magnetic path member.

  In the present invention, for example, at the manufacturing stage of the electromagnetic actuator, a magnetic clearance is formed according to the magnetic force of the permanent magnet, and adjustment is made for each product so that the attractive force acting on the plunger is included in a preferable range. This makes it possible to equalize the magnet attractive force acting on the two plungers in the same product, or to reduce variations in the magnetic attractive force of the electromagnetic actuator due to the permanent magnet production lot. Therefore, variation in response of the electromagnetic actuator can be reduced.

Specifically, the magnetic clearance is formed by a nonmagnetic spacer or space.
When using non-magnetic spacers, for example, several types of spacers having different thicknesses are prepared, and a spacer having an appropriate thickness may be selected according to the magnetic force of the permanent magnet.
In addition, by adopting a configuration in which the magnetic path member is screwed to the holding member, the distance of the magnetic clearance between the permanent magnet and the magnetic path member can be easily adjusted by rotating the screw.

It is sectional drawing at the time of the deenergization of the electromagnetic actuator by 1st Embodiment of this invention. It is an II direction arrow line view (plan view) of FIG. It is sectional drawing at the time of the 1st coil energization of the electromagnetic actuator by 1st Embodiment of this invention. It is a principal part enlarged view of FIG. It is a schematic diagram which shows the force which acts on a plunger at the time of non-energization. It is a schematic diagram which shows the force which acts on a plunger at the time of 1st coil energization. It is a characteristic view which shows the relationship between the stroke and force of a plunger and a control pin. (A) When there is no spacer, (b) It is a characteristic view explaining the dispersion | variation in magnet attraction force when using a spacer. It is sectional drawing at the time of the deenergization of the electromagnetic actuator by 2nd Embodiment of this invention. It is sectional drawing at the time of the deenergization of the electromagnetic actuator by 3rd Embodiment of this invention.

Hereinafter, an electromagnetic actuator according to an embodiment of the present invention will be described with reference to the drawings.
As disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2013-239538), this electromagnetic actuator controls the lift amount of an intake valve or an exhaust valve of an internal combustion engine by a cam integrally provided on a slider that rotates together with a camshaft. It is applied to the valve lift adjusting device to adjust.

The slider of the valve lift adjusting device is provided so as to be movable relative to the camshaft in the axial direction while rotating together with the camshaft, and an engaging groove whose axial position gradually changes according to the rotation angle is formed on the outer periphery. ing. The electromagnetic actuator advances one “operation side restriction pin” of the two restriction pins based on a command from the control means, and engages the tip of the operation side restriction pin with the engagement groove of the slider. Thus, the slider is moved in the axial direction along with the rotation. Further, when the distal end portion of the operating side regulating pin is separated from the engaging groove, the operating side regulating pin is pushed back by the torque of the camshaft.
Since the detailed configuration and operation of the valve lift adjustment device are as described in Patent Document 1, description thereof is omitted here.

(First embodiment)
The configuration of the electromagnetic actuator according to the first embodiment of the present invention will be described with reference to FIGS. The electromagnetic actuator 401 has two restriction pins 601 and 602 arranged in parallel, and one of them is selectively operated as an “operation side restriction pin”. FIG. 1 is a cross-sectional view showing a state in which none of the restriction pins 601 and 602 is operated, and FIGS. 3 and 4 are cross-sectional views showing a state in which the first restriction pin 601 is operated. Note that the sectional view of the second regulating pin 602 in the activated state corresponds to the right and left reversed of FIGS.
As shown in FIG. 2, the electromagnetic actuator 401 is formed symmetrically in the left-right direction in the figure except for the mounting portion 475 that protrudes outside the main body.

The electromagnetic actuator 401 includes coils 451 and 452, lids 501 and 502, permanent magnets 521 and 522, adapters 551 and 552, plungers 651 and 652, springs 761 and 762, etc. corresponding to the two regulation pins 601 and 602. Two are provided.
Here, members whose three-digit code ends with “1” correspond to each other, and members whose three-digit code ends with “2” correspond. Hereinafter, “first” is added before the name of the member whose 3-digit code ends with “1”, and “second” is added before the name of the member whose 3-digit code ends with “2”. . However, as an exception, “1” at the end of “electromagnetic actuator 401” means the first embodiment.

  The regulation pins 601 and 602 and the plungers 651 and 652 correspond to “movable parts”. The first restricting pin 601 and the first plunger 651 are integrally coupled on the pin shaft P1, and reciprocate from the most retracted position shown in FIG. 1 to the most advanced position shown in FIG. Further, the second restriction pin 602 and the second plunger 652 are integrally coupled on the pin shaft P2, and similarly reciprocate.

  Here, the advance distance from the last retracted position of the restriction pins 601 and 602 and the plungers 651 and 652 is called a stroke, the last retracted position is called “zero stroke”, and the most advanced position is called “full stroke”. In the following description, “forward direction” or “forward” corresponds to the downward direction of FIGS. 1, 3, and 4, and “backward direction” or “rearward” corresponds to the upward direction of FIGS. . A direction in which the regulation pins 601 and 602 advance and retreat is referred to as an “axial direction” of the electromagnetic actuator 401, and a direction orthogonal to the axial direction of the electromagnetic actuator 401 is referred to as a “radial direction”.

On the other hand, coils 451 and 452, lids 501 and 502, permanent magnets 521 and 522, adapters 551 and 552, rear yokes 411 and 412, coil cores 421 and 422, front yokes 431 and 432, sleeve 70, mounting plate 78, etc. , Constituting the “stationary part”.
Hereinafter, after describing the structure of a stationary part in order, the structure of a movable part is demonstrated.

  The outer part of the rear part of the stationary part is composed of soft magnetic members such as rear yokes 411 and 412, coil cores 421 and 422, front yokes 431 and 432, coils 451 and 452, bobbins 461 and 462, etc. constituting a magnetic circuit Molded in the mold part 47 and provided integrally behind the mounting plate 78. The resin mold portion 47 is formed with two magnet housing holes 481 and 482 that open rearward, and a connector 49 that protrudes rearward.

  The rear yokes 411 and 412 and the front yokes 431 and 432 are plate-shaped perpendicular to the pin axes P1 and P2 and parallel to each other. The coil cores 421 and 422 have a columnar shape with the coil axes C1 and C2 as axes, and connect the rear yokes 411 and 412 and the front yokes 431 and 432, respectively. Cylindrical plunger guide portions 441 and 442 are formed around the pin shafts P1 and P2 connected to the front yokes 431 and 432, respectively. Both plunger guide portions 441 and 442 are connected between the pin shafts P1 and P2.

  The coils 451 and 452 are configured by winding a winding around the outer periphery of bobbins 461 and 462 that are extrapolated to the coil cores 421 and 422. The bobbins 461 and 462 are made of resin and insulate the coil cores 421 and 422 from the windings of the coils 451 and 452. The coils 451 and 452 generate a magnetic field by energizing any one of the coils corresponding to the operation side regulation pins via the connector 49 from an external power source. The path through which the magnetic flux by this magnetic field passes and the direction of the magnetic flux will be described later.

The magnet accommodation holes 481 and 482 of the resin mold part 47 are formed in a cylindrical shape with the magnet axes M1 and M2 as axes. In the magnet accommodation holes 481 and 482, adapters 551 and 552, permanent magnets 521 and 522, and lids 501 and 502 are accommodated basically in order from the back side.
Furthermore, in this embodiment, according to the variation in the magnetic force of the permanent magnets 521 and 522, between the first permanent magnet 521 and the first adapter 551 and between the second permanent magnet 522 and the second adapter 552. , Non-magnetic spacers 541 and 542 forming magnetic clearances are interposed. For example, in the present embodiment, a relatively thin spacer 541 is interposed between the first permanent magnet 521 and the first adapter 551, and relatively between the second permanent magnet 522 and the second adapter 552. A thick spacer 542 is interposed.
For the spacers 541 and 542, for example, martensitic stainless steel thin plates (shim) or the like having several types of thickness are prepared, and an optimum thickness is selected each time.

As shown in FIGS. 2 and 4, female screw portions 413 and 414 formed in the rear yokes 411 and 412 are exposed on the inner walls of the magnet housing holes 481 and 482. The lids 501 and 502 are held by the rear yokes 411 and 412 when the male screw part 51 formed on the side wall is screwed into the female screw parts 413 and 414, and covers the permanent magnets 521 and 522.
The lids 501 and 502 in the present embodiment correspond to “magnetic path members” recited in the claims. The rear yokes 411 and 412 correspond to “holding members” recited in the claims. The lids 501 and 502 are provided with working engagement portions (not shown) such as driver grooves, for example.

  The permanent magnets 521 and 522 have a plate shape with a circular sectional shape in the radial direction. In the present embodiment, the diameters of the permanent magnets 521 and 522 are set larger than the diameters of the corresponding plungers 651 and 652. That is, the permanent magnets 521 and 522 are formed so that the areas of the end surfaces facing each other are larger than the corresponding plungers 651 and 652.

  As shown in FIG. 4, the first permanent magnet 521 and the second permanent magnet 522 are magnetized so that the directions of the magnetic poles are opposite to each other. For example, in the present embodiment, the first permanent magnet 521 has an N pole on the lid 501 side and an S pole on the plunger 651 side. The second permanent magnet 522 has an S pole on the lid 502 side and an N pole on the plunger 652 side. Thereby, a magnetic circuit as shown in FIG. 5 to be referred to later is formed.

  The adapters 551 and 552 are made of a soft magnetic material such as iron, and are provided at the end portions of the permanent magnets 521 and 522 on the plungers 651 and 652 side. The adapters 551, 552 are magnetized by the permanent magnets 521, 522, and function as “magnetic collecting members” that collect the magnetic flux of the permanent magnets 521, 522 and transmit them to the plungers 651, 652.

The adapters 551 and 552 include a plate-like main body portion 56 having a radial cross-sectional area equivalent to that of the permanent magnets 521 and 522, and a fitting portion 58 that protrudes from the main body portion 56 toward the plungers 651 and 652 in a convex taper shape. Have. The “tapered shape” includes a “conical shape”.
The axes Q1 and Q2 of the fitting portion 58 are offset with respect to the magnet axes M1 and M2, and are arranged so as to coincide with the pin axes P1 and P2 at the center of variation.

  A sleeve 70 constituting the outer shell of the front portion of the stationary portion is provided in a cylindrical shape in front of the center portion of the mounting plate 78. The sleeve 70 is formed with an accommodation hole 72 for accommodating the regulation pins 601 and 602 and the springs 761 and 762. Sliding holes 751 and 752 through which the regulation pins 601 and 602 slide are formed in the hole bottom 74 of the accommodation hole 72. Further, bushes 731 and 732 are fixed inside the plunger guide portions 441 and 442.

Next, the restriction pins 601 and 602 and the plungers 651 and 652 which are movable parts will be described by taking the first restriction pin 601 and the first plunger 651 as an example.
In the restriction pin 601, a shaft main body 611, a connecting portion 621 connected to the plunger 651, and a flange portion 631 constituting a seating surface of the spring 761 are formed coaxially on the pin shaft P <b> 1. The collar portion 631 may be formed by press-fitting a separate collar into the shaft main body 611, or may be manufactured integrally with the shaft main body 611.

  Most of the shaft main body 611 except for the distal end portion 641 is accommodated in the sleeve 70. The shaft body 611 is guided in the hole of the bush 731 at the rear of the sleeve 70, and is slid by being guided in the sliding hole 751 at the front of the sleeve 70. The distal end portion 641 protrudes from the sleeve 70 and engages with the engagement groove of the slide of the valve lift adjusting device when moving forward.

The plunger 651 is formed in a cylindrical shape with a soft magnetic material such as iron and is connected to the connecting portion 621 of the restriction pin 601. The plunger 651 is guided by the plunger guide portion 441 and moves forward and backward integrally with the restriction pin 601. A concave tapered receiving portion 66 for receiving the fitting portion 58 is formed on the end surface of the plunger 651 on the adapter 551 side.
The plunger 651 is biased toward the adapter 551, that is, in the backward direction by the magnet attractive force of the permanent magnet 521. When the plunger 651 is attracted to the adapter 551, the fitting portion 58 of the adapter 551 is fitted to the receiving portion 66 of the plunger 651.
The above configuration is the same for the second restriction pin 602 and the second plunger 652.

  The springs 761 and 762 are extrapolated to the shaft main bodies 611 and 612 of the restriction pins 601 and 602, and both ends are supported between the bushes 731 and 732 and the flange portions 631 and 632. The springs 761 and 762 bias the flanges 631 and 632 away from the bushes 731 and 732, so that the regulation pins 601 and 602 are biased in the forward direction.

  As described above, the first plunger 651 and the first restricting pin 601 and the second plunger 652 and the second restricting pin 602 that are integrally connected to each other include the magnet attractive force of the permanent magnets 521 and 522 and the spring 761. 762 spring forces act in opposite directions. Then, the plungers 651 and 652 move in a direction in which the larger one of them is urged in accordance with fluctuations in the magnet attractive force and the spring force.

Next, the operation of the electromagnetic actuator 401 having the above configuration will be described with reference to FIGS. 5 shows the magnetic flux flowing through the first plunger 651 and the second plunger 652 when the first coil is energized.
FIG. 7 is a characteristic diagram in which the horizontal axis represents the stroke of the plunger and the regulating pin, and the vertical axis represents the force acting on the plunger and the regulating pin. Here, the code | symbol in description is described as an example when the 1st control pin 601 is act | operated. In FIG. 7, the characteristic line of the magnet attraction force Fm at the time of non-energization is shown by a solid line, and the characteristic line of the magnet attraction force Fm− reduced by the reverse direction magnetic force Fc generated at the time of coil energization is shown by a one-dot chain line.

The spring force Fsp of the spring 761 is indicated by a broken line. The spring force Fsp linearly decreases as the stroke increases from the spring force Fsp0 at the zero stroke L0. The spring force Fsp at the full stroke Lf corresponds to “on holding force Fh _ON ” that holds the plunger 651 and the restriction pin 601 at the most advanced position.

(When not energized)
As shown in FIG. 5, the magnetic flux Φ0 generated by the permanent magnets 521 and 522 from the N pole of the second permanent magnet 522 when not energized, the second adapter 552, the second plunger 652, the plunger guide portions 442 and 441, and the first plunger. 651, reaches the south pole of the first permanent magnet 521 via the first adapter 551, and further, from the north pole of the first permanent magnet 521, the first lid 501, the first rear yoke 411, the first coil core 421, the first A magnetic circuit is formed that reaches the south pole of the second permanent magnet 522 via the front yoke 431, the second front yoke 432, the second coil core 422, the second rear yoke 412, and the second lid 502.

In the zero stroke L0 in FIG. 7, the magnet attraction force Fm0 due to the magnetic flux Φ0 exceeds the spring force Fsp0, and the difference is “off holding force Fh _OFF ” that holds the plungers 651 and 652 and the regulation pins 601 and 602 in the last retracted position. It becomes. The first plunger 651 is attracted and held by the first permanent magnet 521 and the second plunger 652 is attracted and held by the second permanent magnet 522 by the _OFF holding force Fh _OFF .
Thereby, both the front end portions 641 and 642 of the first restricting pin 601 and the second restricting pin 602 are maintained at the last retracted position, and are separated from the engaging groove of the slider in the valve lift adjusting device.

(When the first coil is energized)
As shown in FIG. 6, when a current is applied to the first coil 451 from the back of the drawing to the front on the left side of the drawing with respect to the coil axis C1, and from the front of the drawing to the back on the right side of the drawing, the first coil core 421 is illustrated. A coil magnetic flux Φ1 (long broken line) is generated from the bottom to the top. Since the coil magnetic flux Φ1 is generated in a direction to cancel the magnetic flux Φ0 by the first permanent magnet 521, the magnet attractive force acting on the first plunger 651 is reduced to Fm− shown in FIG. In other words, the first permanent magnet 521 is demagnetized by the coil magnetic flux Φ1. Note that energization of the first coil 451 in this example corresponds to “reverse direction energization” in Patent Document 1.

As a result, the magnet attraction force at zero stroke L0 FM- becomes smaller than the spring force Fsp0, off the holding force Fh _OFF is lost. As a result, the first restriction pin 601 moves forward by a force obtained by subtracting the magnet attractive force Fm− from the spring force Fsp of the first spring 761. Then, even after the energization is stopped after exceeding the threshold stroke Lt at which the magnet attractive force Fm and the spring force Fsp become equal, the first restriction pin 601 moves forward to the full stroke Lf by the spring force Fsp. When the full stroke Lf is reached, the first restriction pin 601 is held by the _ON holding force Fh _ON .
Thus, when the first coil is energized, the first restricting pin 601 operates as an “operating side restricting pin”, and the tip end portion 641 of the first restricting pin 601 engages with the engaging groove of the slider.

  On the other hand, the tip 641 of the first restricting pin 601 is pushed back by the bottom of the engaging groove when it is separated from the engaging groove of the slider. The stroke when the amount of pushing back is the minimum is referred to as the maximum pull-in stroke Lu. The electromagnetic actuator 401 must have at least a magnet attractive force Fm for retracting the first plunger 651 from the maximum retracting stroke Lu to the zero stroke L0.

  For this purpose, it is necessary that the maximum retracting stroke Lu is smaller than the threshold stroke Lt, and the magnet attractive force Fm exceeds the spring force Fsp in the maximum retracting stroke Lu. In other words, the magnet attraction force Fm and the spring force Fsp need to be set so that the “retraction margin force Fu” obtained by subtracting the spring force Fsp from the magnet attraction force Fm at the maximum retraction stroke Lu is greater than zero. .

In the present embodiment, since the adapter 551 and the plunger 651 are formed with the tapered fitting portion 58 and the receiving portion 66, a part of the fitting portion 58 and the receiving portion 66 are axially arranged in a predetermined stroke section. It overlaps and the change of the magnet attractive force Fm accompanying a stroke change is suppressed. That is, a flat portion of the stroke-magnet attractive force characteristic line is generated in the portion X shown in FIG.
As a result, the threshold stroke Lt is shifted in a direction larger than the characteristic line Fmn (two-dot chain line) when the tapered fitting portion and the receiving portion are not provided. Further, it is possible to secure the pull-in margin force Fu at the maximum pull-in stroke Lu.

The above is the operation when the first coil is energized. When the first coil is energized, no current flows through the second coil 452, and the second coil 452 generates no magnetic flux in any direction. That is, the “same direction energization” in Patent Document 1 does not exist in this embodiment.
On the other hand, when the second restriction pin 602 is moved forward as an “operation side restriction pin”, the direction in which the magnetic flux Φ0 by the second permanent magnet 522 is canceled, that is, the second coil core 422 is lowered from the top of the figure, contrary to the above description. An electric current is passed through the second coil 452 so as to generate a coil magnetic flux in the direction toward.

  As described above, the electromagnetic actuator 401 does not operate any of the restriction pins 601 and 602 when de-energized, operates only the first restriction pin 601 when the first coil is energized, and only the second restriction pin 602 when the second coil is energized. Operates. Thus, the electromagnetic actuator 401 selectively activates one of the two restriction pins 601 and 602 by switching the energized coils 451 and 452.

By the way, in an actual product, there is a variation in magnetic force between individual permanent magnets. Therefore, the magnetic force of the 1st permanent magnet 521 and the 2nd permanent magnet 522 in the same product becomes imbalanced, or the variation in the magnetic force of the permanent magnet due to the production time of the electromagnetic actuator depends on the production lot of the permanent magnet procured as a part. May occur.
When the magnetic force of the permanent magnet varies, the time from when the energization to the coil starts until the magnet attracting force Fm falls below the spring force Fsp and the regulating pins 601 and 602 operate is affected. As a result, the responsiveness of the electromagnetic actuator 401 varies.

  Therefore, in this embodiment, according to the variation in the magnetic force of the permanent magnets 521 and 522, magnetic clearance is formed by interposing the nonmagnetic spacers 541 and 542 between the permanent magnets 521 and 522 and the adapters 551 and 552. By doing so, the magnet attractive force acting on the plungers 651 and 652 is adjusted. Specifically, for example, at the manufacturing stage of the electromagnetic actuator 401, adjustment is made for each product so that the magnet attractive force Fm acting on the plungers 651 and 652 is included in a preferable range. This adjustment will be described with reference to FIG.

FIG. 8A shows a stroke-magnet attractive force characteristic line when there is no spacer, and FIG. 8B shows a stroke-magnet attractive force characteristic line when the spacer is used. The minimum suction force Fm-min common to both figures is the lowest suction force that can retract the regulating pins 601 and 602 in the maximum retracting stroke Lu.
In FIG. 8A, the magnet attractive force Fm2 ′ acting on the second plunger 652 is larger than the magnet attractive force Fm1 ′ acting on the first plunger 651, and the difference between the two at the zero stroke L0 is ΔFm ′. .

On the other hand, if the magnetic clearance is formed by interposing the spacers 541 and 542 between the permanent magnets 521 and 522 and the adapters 551 and 552, the magnet attractive force is reduced according to the magnitude of the magnetic clearance. In view of this, the relatively thick spacer 542 is interposed on the side where the magnet attractive force Fm2 ′ without the spacer is large, and the relatively thin spacer 541 is interposed on the side where the magnet attractive force Fm1 ′ is small. Adjust so that the magnet attracting force is even.
As a result, as shown in FIG. 8B, the difference ΔFm between the magnet attraction force Fm2 acting on the second plunger 652 and the magnet attraction force Fm1 acting on the first plunger 651 in the zero stroke L0 is shown in FIG. It becomes smaller than ΔFm ′ shown in a).

(effect)
The effect of the electromagnetic actuator 401 of this embodiment will be described.
(1) This embodiment forms a magnetic clearance between the permanent magnets 521 and 522 and the adapters 551 and 552 in accordance with variations in the magnetic force of the permanent magnets 521 and 522, and attracts the magnet acting on the plungers 651 and 652. The force is adjusted so as to be within a preferable range.
Thereby, the magnet attraction force acting on the first plunger 651 and the second plunger 652 in the same product is made equal, or variation in the magnet attraction force of the electromagnetic actuator 401 due to the production lot of the permanent magnets 521 and 522 is reduced. be able to. Therefore, variation in responsiveness of the electromagnetic actuator 401 can be reduced.

  (2) In the present embodiment, since the magnetic clearance is formed by interposing the nonmagnetic spacers 541 and 542 between the permanent magnets 521 and 522 and the adapters 551 and 552, the operation is easy.

(3) In the present embodiment, the adapters 551 and 552 and the plungers 651 and 652 are provided with the tapered fitting portion 58 and the receiving portion 66, thereby providing a flat portion in the stroke-magnet attractive force characteristic line. The threshold stroke Lt can be shifted in the direction of increasing (see the part X in FIG. 7). Therefore, the urging force of the springs 761 and 762 can be increased while ensuring the pull-in margin force Fu at the maximum pull-in stroke Lu, so that the responsiveness of the regulation pins 601 and 602 is improved and the ON holding force Fh _ON is increased. Is advantageous.

  Next, another embodiment for forming a magnetic clearance according to the magnetic force of the permanent magnets 521 and 522 will be described. In the following embodiment, substantially the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

(Second Embodiment)
The electromagnetic actuator 402 according to the second embodiment of the present invention shown in FIG. 9 differs from the first embodiment only in the positions where the spacers 541 and 542 are provided. That is, in the second embodiment, the magnetic clearance is formed by interposing the spacers 541 and 542 between the permanent magnets 521 and 522 and the lids 501 and 502 as “magnetic path members”.
The second embodiment has the same effects as the first embodiment. Further, since the spacers 541 and 542 can be added or replaced only by removing the lids 501 and 502 from the magnet housing holes 481 and 482, the number of work steps can be reduced.

(Third embodiment)
The electromagnetic actuator 403 according to the third embodiment of the present invention shown in FIG. 10 is different from the second embodiment in that a magnetic clearance is formed by spaces 591 and 592 between the permanent magnets 521 and 522 and the lids 501 and 502. Different. The distances of the spaces 591 and 592 can be adjusted by rotating the screws between the male threaded portion 51 of the lids 501 and 502 and the female threaded portions 413 and 414 of the rear yokes 411 and 412.
The third embodiment has the same operational effects as the first and second embodiments. In addition, when the spacer is used, the thickness selection pattern is finite, but in the third embodiment, the stepless adjustment is possible.

(Other embodiments)
(A) As a configuration for forming the magnetic clearance, the configurations of the first to third embodiments may be combined. That is, it is good also as a structure which adjusts a magnet attraction force using both the spacer between a permanent magnet and an adapter, and the spacer or space between a permanent magnet and a cover.

  (A) In the above-described embodiment, the permanent magnets 521 and 522 are formed such that the areas of the end faces facing each other are larger than the corresponding plungers 651 and 652. However, when the magnetic flux transmitted from the permanent magnet to the plunger is sufficiently secured, the area of the end face of the permanent magnet may be set equal to or less than the area of the end face of the opposing plunger.

(C) When forming a fitting part and a receiving part in an adapter and a plunger, the shape of a fitting part and a receiving part is not restricted to a taper shape. A plurality of fitting portions and receiving portions may be provided for a pair of adapters and plungers corresponding to each other. Or you may make it transmit a magnetic flux between planes, without providing a fitting part and a receiving part in an adapter and a plunger.
(D) The configuration of each part of the electromagnetic actuator other than the configuration relating to the spacer or space forming the magnetic clearance, for example, the components, shape, positional relationship, etc. of the permanent magnet or the magnetic circuit is not limited to the above embodiment. In the above embodiment, two coils corresponding to each regulation pin are provided. However, as disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2013-239538), a configuration in which one coil is provided may be employed.

(E) The present invention may be applied to an electromagnetic actuator having three or more restriction pins. In that case, an electromagnetic actuator that forms a magnetic clearance in accordance with a variation in magnetic force for at least two permanent magnets is included in the scope of the present invention.
As mentioned above, this invention is not limited to such embodiment, In the range which does not deviate from the meaning of invention, it can implement with a various form.

401, 402, 403 ... electromagnetic actuator,
451, 452 ... Coils,
501, 502 ... Lid (magnetic path member),
521, 522 ... Permanent magnet,
551, 552... Adapter (magnet collecting member),
601, 602... Regulating pin,
641, 642... Tip portion,
651, 652 ... Plunger,
761, 762... Spring.

Claims (4)

This is applied to a valve lift adjustment device that adjusts the lift amount of an intake valve or an exhaust valve of an internal combustion engine, and is formed as a slider that can move relative to the camshaft in the axial direction while rotating together with the camshaft of the valve lift adjustment device. When the front end portion (641, 642) of one of the two regulation pins (601, 602) is engaged with the engagement groove, the actuation side regulation pin is advanced, and the actuation side An electromagnetic actuator (401, 402, 403) in which the operating side regulation pin is pushed back by the torque of the camshaft when the tip of the regulation pin is separated from the engagement groove,
A first restricting pin (601) and a second restricting pin (602) which are juxtaposed in advance with respect to the engaging groove;
A first plunger (651) and a second plunger (652) which are formed of a soft magnetic material and the corresponding restriction pins are connected to one end;
A first permanent magnet (501) and a second permanent magnet (502) provided so that the directions of the magnetic poles are opposite to each other, and attracting the corresponding plunger in the backward direction;
A first magnetic flux collecting member (551) and a second magnetic flux collector that are formed of a soft magnetic material, are provided at the end of the corresponding permanent magnet on the plunger side, and collect the magnetic flux of the permanent magnet and transmit it to the corresponding plunger. A magnetic member (552);
A first magnetic path member (501) and a second magnetic field which are formed of a soft magnetic material and are provided on the opposite side of the corresponding permanent magnet from the plunger and constitute a magnetic path passing through the corresponding permanent magnet and the plunger. A road member (502);
Coils (451, 452) for generating a magnetic flux in a reverse direction with respect to any one of the first permanent magnet and the second permanent magnet and reducing a magnet attractive force for attracting the corresponding plunger;
A first spring (761) and a second spring (762) that are operated in the forward direction by an urging force, with the restriction pin on the side where the magnet attractive force is reduced by energization of the coil as the action side restriction pin;
With
An electromagnetic actuator, wherein a magnetic clearance is formed between the permanent magnet and the magnetic flux collecting member or between the permanent magnet and the magnetic path member according to the magnetic force of the permanent magnet.   The magnetic clearance is formed by a non-magnetic spacer (541, 542) interposed between the permanent magnet and the magnetism collecting member or between the permanent magnet and the magnetic path member. The electromagnetic actuator (401, 402) according to claim 1, characterized by: The two magnetic path members are screwed into holding members (411, 412) that hold the magnetic path members,
The electromagnetic actuator according to claim 1, wherein the magnetic clearance is formed by a space (591, 592) between the permanent magnet and the magnetic path member, the distance of which can be adjusted by rotation of a screw. 403).   The said magnetism collecting member has a fitting part (58) which protrudes in the shape of a taper to the said plunger side, and fits into the receiving part (66) formed in the said plunger. 4. The electromagnetic actuator according to any one of 3.

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