JP6314847B2 - Electromagnetic actuator - Google Patents

Description

  The present invention relates to an electromagnetic actuator that is applied to a valve lift adjusting device for an internal combustion engine and drives an output pin by electromagnetic force.

2. Description of the Related Art Conventionally, an electromagnetic actuator that drives an output pin that is movably provided with a permanent magnet by an electromagnetic force generated by a coil is known.
For example, Patent Document 1 discloses a configuration that prevents a reduction in the operating speed of the output pin due to the viscous resistance of oil, particularly at low temperatures, by providing a passage for discharging the oil introduced into the electromagnetic actuator. Has been.

DE 202007010814U1 specification

  In the electromagnetic actuator of Patent Document 1, plates are joined to both sides of the permanent magnet in the axial direction. The front plate joined to the front end side of the output pin is required to make the clearance between the outer peripheral wall of the front plate and the inner peripheral wall of the yoke as small as possible in order to reduce the magnetic gap between the front yoke and the surrounding yoke. However, when the viscosity of the oil increases at a low temperature, there is a problem that the oil accumulated in the narrow gap becomes the operating resistance of the front plate, and the forward speed of the output pin decreases.

  The present invention has been created in view of the above-described problems, and an object of the present invention is to provide an electromagnetic actuator that reduces operating resistance due to oil viscosity when the output pin moves forward.

The present invention is an electromagnetic actuator that 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 drives an output pin by electromagnetic force, and includes an output pin, a permanent magnet, a front plate, A stator, a coil, and a yoke.
The output pin is provided so as to be capable of moving forward with respect to the cam shaft of the valve lift adjusting device, and the tip portion in contact with the cam shaft is pushed back in the backward direction by the torque of the cam shaft.

The plate-like permanent magnet is magnetized so that both ends in the axial direction have different polarities at the base end portion of the output pin, and moves together with the output pin.
The front plate is formed of a soft magnetic material, joined to the permanent magnet at the tip end side of the output pin with respect to the permanent magnet, and has an outer diameter larger than the outer diameter of the permanent magnet.
The stator is formed of a soft magnetic material, and is provided on the base end side of the output pin with respect to the permanent magnet.
The coil generates a repulsive force between the stator and the permanent magnet by generating a magnetic field opposite to the magnetic field of the permanent magnet when energized.

The yoke is formed of a soft magnetic material in a cylindrical shape, has an inner peripheral wall facing the outer peripheral wall of the front plate, and forms a magnetic circuit that passes through the stator and the front plate.
The front plate is characterized in that, at least in the circumferential direction of the outer peripheral wall, an enlarged-diameter portion whose outer diameter increases from the proximal end side to the distal end side of the output pin is formed.
Preferably, the front plate has an enlarged diameter portion over the entire circumference of the outer peripheral wall. The enlarged diameter portion is formed so as to be inclined linearly in the axial section, for example.

  In the present invention, since the diameter-enlarged portion is formed on the outer peripheral wall of the front plate, when oil is introduced around the movable portion, the oil accumulated in the gap between the outer peripheral wall of the front plate and the inner peripheral wall of the yoke is As the front plate moves forward, the gap is likely to flow out backward. Therefore, even when the viscosity of the oil becomes high at a low temperature, the operating resistance when the output pin moves forward can be reduced.

It is sectional drawing at the time of the non-energization of the electromagnetic actuator by 1st Embodiment of this invention (at the time of an output pin backward movement). It is sectional drawing at the time of electricity supply of the electromagnetic actuator of FIG. 1 (at the time of an output pin advance). It is the III section enlarged view of FIG. FIG. 4 is a sectional view taken along line IV-IV (radial direction) in FIG. 3. (A) The Va part enlarged view of FIG. 3 explaining the effect | action of a diameter enlarged part, (b) The enlarged view of the outer peripheral wall of a comparative example. It is radial direction sectional drawing of the electromagnetic actuator by 2nd Embodiment of this invention. It is an enlarged view of the outer peripheral wall of the front plate of the electromagnetic actuator by other embodiment of this invention.

Hereinafter, an electromagnetic actuator according to an embodiment of the present invention will be described with reference to the drawings. This electromagnetic actuator 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.
(First embodiment)
The configuration of the electromagnetic actuator of the first embodiment will be described with reference to FIGS. As shown in FIGS. 1 and 2, the electromagnetic actuator 101 is mounted in the mounting hole 92 of the engine head 90 and operates the output pin 60 with respect to the camshaft 94 of the valve lift adjusting device.

  Hereinafter, operating the output pin 60 in a direction approaching the camshaft 94 is referred to as “advancing”, and operating the output pin 60 in a direction away from the camshaft 94 is referred to as “retreating”. FIG. 1 shows a state where the output pin 60 is in the backward limit, and FIG. 2 shows a state where the output pin 60 is in the forward limit. The end of the output pin 60 on the camshaft 94 side is referred to as a distal end portion 64, and the end opposite to the distal end portion 64 is referred to as a proximal end portion 61.

  Since the overall configuration of the valve lift adjusting device is well known, illustration and detailed description thereof are omitted. The electromagnetic actuator 101 advances the output pin 60 by the electromagnetic force generated by energizing the coil 31 when the output pin 60 faces the minor axis Ra side with the rotation of the camshaft 94 whose rotation axis is C. Let

  On the other hand, when the camshaft 94 is rotated so that the long diameter Rb side faces the output pin 60 with the distal end portion 64 of the output pin 60 in contact with the camshaft 94, the output pin 60 is moved backward by the torque of the camshaft 94. Pushed back. At this time, it is pushed back to the position of the retracting stroke Lu, and retracts from the position of the retracting stroke Lu to the retreat limit by the magnetic force of the permanent magnet 40 of the electromagnetic actuator 101 itself.

  Next, a detailed configuration of the electromagnetic actuator 101 will be described. The electromagnetic actuator 101 is roughly divided into a stationary part 13 fixed to the engine head 90 and a movable part 14 reciprocating in the axial direction. The stationary part 13 and the movable part 14 are provided coaxially with respect to the central axis O (see FIGS. 3 and 4).

The stationary part 13 includes a coil 31, a stator 32, a yoke 35, and the like.
The coil 31 is configured by winding a winding around the outer periphery of the bobbin 30 that is extrapolated to the stator 32. The bobbin 30 is made of resin and insulates the winding of the coil 31 from the stator 32. A resin mold part 16 is provided integrally with the connector part 17 on the side opposite to the movable part 14 with respect to the coil 31. When energized from an external power source (not shown) via the terminal 18 of the connector unit 17, the coil 31 generates a magnetic field. The action of the electromagnetic force generated by this magnetic field will be described later.

  The stator 32 is formed of a soft magnetic material and is provided on the proximal end side of the output pin 60 with respect to the permanent magnet 40. Most of the stator 32 is positioned inside the diameter of the coil 31 and functions as a coil core. At the end portion of the stator 32 on the movable portion 14 side, a facing portion 34 having a relatively large outer diameter and facing the rear plate 44 of the movable portion 14 in a wide area is formed.

  The yoke 35 is a soft magnetic material and is formed in a cylindrical shape that is substantially coaxial with the coil 31 and the movable portion 14. A coil 31, a stator 32, a resin mold portion 16, and the like are accommodated inside the yoke 35, and magnetism is transmitted to each other at a portion that is in contact with or close to the stator 32. Seal rings 81 and 82 for ensuring a seal with the inner periphery of the yoke 35 are provided on the outer periphery of the resin mold portion 16 and the outer periphery of the facing portion 34 of the stator 32, respectively.

Further, in the axial range in which the movable portion 14 moves, the inner peripheral wall 36 of the yoke 35 faces an outer peripheral wall 46 of a front plate 45 described later. Therefore, the yoke 35 forms a magnetic circuit that passes through the stator 32 and the front plate 45. In a range facing the outer peripheral wall 46 of the front plate 45, the yoke 35 is formed in a substantially straight cylindrical shape, that is, the inner diameter of the inner peripheral wall 36 is substantially constant.
A flange 39 used for attachment to the engine head 90 is formed in the opening of the yoke 35 on the sleeve 70 side.

The sleeve 70 includes a base portion 71, a cylindrical portion 73, and the like. The base 71 is inserted into the mounting hole 92 of the engine head 90. A seal ring 83 that secures a seal with the inner periphery of the mounting hole 92 is provided on the outer periphery of the base 71. An end surface 72 on the coil 31 side of the base 71 faces a front end surface 457 of a front plate 45 described later. An oil passage 76 that penetrates the base 71 in the axial direction is formed around the end surface 72. Oil in the engine is introduced around the movable portion 14 via the oil passage 76.
The cylindrical portion 73 protrudes from the base portion 71 so that the distal end surface 74 faces the camshaft 94. An insertion hole 75 through which the output pin 60 is inserted is formed along the central axis of the cylindrical portion 73.

Next, the description of the movable part 14 will be given. The movable portion 14 includes a permanent magnet 40, a rear plate 44, a front plate 45, an output pin 60, and the like, and moves together.
The permanent magnet 40 is a plate having a circular cross-section in the radial direction, and is fixed to the base end portion 61 of the output pin 60. The permanent magnet 40 is magnetized in the axial direction such that, for example, the rear plate 44 side is an N pole and the front plate 45 side is an S pole (see FIG. 3). The arrangement of the N pole and the S pole may be reversed.

The rear plate 44 and the front plate 45 are made of a soft magnetic material, and are joined to the permanent magnet 40 on the proximal end side (coil 31 side) and the distal end side (sleeve 70 side) of the output pin 60 with respect to the permanent magnet 40, respectively. ing. In the case of the magnetic pole arrangement illustrated in FIG. 3, the rear plate 44 is regarded as the N pole, and the front plate 45 is regarded as the S pole.
Hereinafter, the end surface on the coil 31 side of the rear plate 44 is referred to as a rear end surface 443, and the end surface on the sleeve 70 side of the front plate 45 is referred to as a front end surface 457. Further, the end surface of the front plate 45 on the permanent magnet 40 side is referred to as a joint surface 454.

  The output pin 60 is provided so that the outer diameter of the sliding portion 65 can slide within the inner diameter of the insertion hole 75 of the sleeve 70. In the present embodiment, the base end portion 61 of the output pin 60 passes through holes formed in the central portions of the permanent magnet 40, the rear plate 44, and the front plate 45, and is fixed to each member. In this configuration, the output pin 60 is formed of a nonmagnetic material in order to prevent a magnetic short circuit between the rear plate 44 and the front plate 45. In addition, the broken-line hatching attached | subjected to the cross section of the output pin 60 in FIG. 4 represents the nonmagnetic material.

In the non-energized state shown in FIGS. 1 and 3, the movable portion 14 is held in the backward limit by the magnetic attractive force between the rear end surface 443 of the rear plate 44 and the opposed portion end surface 340 of the stator 32. This magnetic attraction force is set so that at least the movable portion 14 can be attracted from the position of the drawing stroke Lu to the retreat limit.
When the movable portion 14 is held in the backward limit by the magnetic attractive force of the permanent magnet 40, as indicated by the broken arrow ΦM, “N pole of the permanent magnet 40 → rear plate 44 → stator 32 → yoke 35 → front plate 45 → permanently”. A magnetic circuit is generated by the route of “S pole of magnet 40”.

In this magnetic circuit, since the gap between the inner peripheral wall 36 of the yoke 35 and the outer peripheral wall 46 of the front plate 45 is a magnetic gap, the dimension is preferably set so that the gap is as small as possible. For example, the minimum value δ of the gap is set to about 0.1 to 0.3 mm.
On the other hand, it is necessary to ensure a large magnetic gap between the inner peripheral wall 36 of the yoke 35 and the rear plate 44 and the permanent magnet 40 in order to prevent magnetism from being short-circuited. Therefore, the outer diameter of the front plate 45 is formed larger than the outer diameter of the permanent magnet 40.

  The coil 31 generates a magnetic field in the opposite direction to the magnetic field of the permanent magnet 40 when energized. For example, in the case of the magnetic pole arrangement shown in FIG. 3, a magnetic field is generated in which the connector portion 17 side of the stator 32 is an S pole and the facing portion 34 side is an N pole. In other words, the winding direction of the coil 31 and the energization direction of the current are set so that such a magnetic field is generated.

Then, since the rear plate 44 and the facing portion 34 of the stator 32 have the same polarity, a repulsive force as an electromagnetic force is generated between the rear end surface 443 of the rear plate 44 and the facing portion end surface 340 of the stator 32. Due to this repulsive force, the movable portion 14 moves forward from the backward limit.
When the front end surface 457 of the front plate 45 approaches the end surface 72 of the sleeve 70, the movable portion 14 is held at the forward limit by the magnetic attractive force between the front end surface 457 and the sleeve end surface 72 as shown in FIG. .

  A feature of the present invention resides in the shape of the outer peripheral wall 46 of the front plate 45 facing the inner peripheral wall 36 of the yoke 35. As shown in FIGS. 3 and 4, the outer peripheral wall 46 has an outer diameter that expands from the joint surface 454 side, which is the proximal end side of the output pin 60, toward the front end surface 457 side, which is the distal end side of the output pin 60. A diameter portion 461 is formed. In the first embodiment, as shown in FIG. 4, the enlarged diameter portion 461 is formed over the entire circumference of the outer peripheral wall 46.

(effect)
The effects of the above configuration will be described with reference to FIG.
(1) FIG. 5A shows the gap between the outer peripheral wall 46 of the front plate 45 and the inner peripheral wall 36 of the yoke 35 in the electromagnetic actuator 101 of the first embodiment, and FIG. The state where the oil L has accumulated is shown. As described above, the minimum value δ of the gap is set to about 0.1 to 0.3 mm, for example.

  In the comparative example, the outer peripheral wall 49 of the front plate 45 has a constant outer diameter from the joining surface 454 side to the front end surface 457 side. Therefore, when the viscosity of the oil L becomes high at low temperatures, the oil L in the gap is unlikely to flow out when the front plate 45 moves forward as indicated by the block arrow, resulting in an operating resistance. Therefore, there arises a problem that the forward speed of the output pin 60 decreases.

On the other hand, in the first embodiment of the present invention, the outer peripheral wall 46 of the front plate 45 is formed with an enlarged diameter portion 461 whose outer diameter increases from the joining surface 454 side toward the front end surface 457.
As a result, the oil L collected in the gap between the outer peripheral wall 46 of the front plate 45 and the inner peripheral wall 36 of the yoke 35 is likely to flow out to the rear where the gap increases as the front plate 45 advances. Therefore, even when the viscosity of the oil L becomes high at low temperatures, the operating resistance when the output pin 60 moves forward can be reduced.
Note that when the output pin 60 is retracted, it is forcibly pushed back by the torque of the camshaft 94, so that the operating resistance due to the viscosity of the oil L does not matter.

(2) In the first embodiment, the enlarged diameter portion 461 is formed over the entire circumference of the outer peripheral wall 46 of the front plate 45. Thereby, the effect of (1) can be obtained to the maximum extent.
(3) The enlarged diameter portion 461 is formed so as to be inclined linearly in the axial section. Thereby, the processing of the front plate 45 is facilitated.

(Second Embodiment)
Next, the electromagnetic actuator of 2nd Embodiment is demonstrated with reference to FIG. 6 corresponding to FIG. 4 of 1st Embodiment. In the following description of the embodiment, the same reference numerals are given to substantially the same components as those in the first embodiment, and the description will be omitted.

  In the electromagnetic actuator 101 of the first embodiment, a diameter-expanded portion 461 is formed over the entire circumference of the outer peripheral wall 46 of the front plate 45 (see FIG. 4). On the other hand, in the electromagnetic actuator 102 of the second embodiment, the diameter-enlarged portion 461 is formed only in the two ranges separated by the central angle α in the circumferential direction of the outer peripheral wall 46. In other ranges, the outer peripheral wall 46 is formed in a straight shape, for example.

  As described above, the enlarged diameter portion 461 does not always need to be formed over the entire circumference of the outer peripheral wall 46, and may be formed at least at a part in the circumferential direction of the outer peripheral wall 46. Since the oil accumulated in the gap easily flows backward in the range where the enlarged diameter portion 461 is formed, the operating resistance of the front plate 45 as a whole can be reduced.

(Other embodiments)
(A) An example of another embodiment relating to the shape of the enlarged diameter portion formed on the outer peripheral wall of the front plate 45 is shown in FIG. The outer peripheral wall 47 shown in FIG. 7A is formed with an enlarged diameter portion 471 having a substantially arc shape in the axial cross section. In the outer peripheral wall 48 shown in FIG. 7B, an enlarged diameter portion 481 having a stepped shape in the axial cross section is formed. Each of the enlarged diameter portions 471 and 481 is formed so that the outer diameter increases from the joining surface 454 side toward the front end surface 457 side. Thus, the same effects as those in the above embodiment can be obtained regardless of the shape of the enlarged diameter portion.

(A) About the joining of the members in the movable portion 14, the output pin 60 is not limited to the form of passing through the three members of the front plate 45, the permanent magnet 40 and the rear plate 44. For example, the rear plate, the permanent magnet, and the front plate may be joined in advance, and the base end portion of the output pin may be joined to the front plate portion of the joined body.
In this embodiment, since a magnetic short circuit between the rear plate and the front plate due to the output pin straddling and abutting does not occur, the output pin may be formed of a soft magnetic material. Further, the base end portion of the output pin is not mechanically fixed to the front plate, but may be attracted by a magnetic attractive force. In other words, the members of the movable portion do not need to be provided integrally, and may be “movable together”.

  (C) In addition, the configuration of each part of the electromagnetic actuator other than the configuration in which the enlarged diameter portion is formed on the outer peripheral wall of the front plate is not limited to the above embodiment. For example, the shape and positional relationship of magnetic circuit components such as a stator and a yoke may be changed as appropriate.

(D) The present invention may be applied to an electromagnetic actuator having two or more sets of stationary parts and movable parts.
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.

101, 102 ... electromagnetic actuator,
31 ... Coil,
32 ... stator,
35 ... Yoke, 36 ... Inner wall,
40: Permanent magnet,
45 ・ ・ ・ Front plate,
46, 47, 48 ... outer peripheral wall,
461, 471, 481...
60 ... Output pin 61 ... Base end part 64 ... Tip part,
94: Camshaft.

Claims (3)

An electromagnetic actuator that 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 drives an output pin by electromagnetic force,
An output pin (60) provided so as to be capable of moving forward with respect to the cam shaft (94) of the valve lift adjusting device, and having a tip end (64) in contact with the cam shaft pushed back in the backward direction by the torque of the cam shaft. When,
A plate-like permanent magnet (40) which is magnetized so that both ends in the axial direction have different polarities at the base end portion (61) of the output pin and moves together with the output pin;
A front plate (45) formed of a soft magnetic material, joined to the permanent magnet on the tip side of the output pin with respect to the permanent magnet, and having an outer diameter larger than the outer diameter of the permanent magnet;
A stator (32) formed of a soft magnetic material and provided on the base end side of the output pin with respect to the permanent magnet;
A coil (31) for generating a repulsive force between the stator and the permanent magnet by generating a magnetic field opposite to the magnetic field of the permanent magnet when energized;
A yoke formed of a soft magnetic material in a cylindrical shape and having an inner peripheral wall (36) facing the outer peripheral wall (46, 47, 48) of the front plate and forming a magnetic circuit via the stator and the front plate (35) and
With
The front plate is formed with an enlarged portion (461, 471, 481) whose outer diameter increases from the proximal end side to the distal end side of the output pin in at least part of the circumferential direction of the outer peripheral wall. An electromagnetic actuator characterized by that.   The electromagnetic actuator according to claim 1, wherein the front plate has the enlarged diameter portion formed over the entire circumference of the outer peripheral wall.   The electromagnetic actuator according to claim 1, wherein the enlarged-diameter portion is formed so as to incline linearly in an axial cross section.

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