JP2003189576A - Supporting structure for linear actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a supporting structure for a linear actuator capable of obtaining a sufficient shock relaxation effect without increasing the mass of a movable part. <P>SOLUTION: The supporting structure for the linear actuator 10 comprises a stator 30 and a movable element 12 driven to advance or retreat on a straight line by the stator in such a manner that the stator is fixed to a base. The stator 30 is supported by rots 17, 18 at a plurality of positions at the base in a state in which the stator 30 can advance or retreat in parallel with the moving direction of the movable element, and permanent magnets 25, 26 or 27, 29 ar provided at the base side and the stator of the supports in such a manner that opposed surfaces of the magnet have the same polarity. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear actuator support structure, and for example, to a linear actuator support structure capable of reducing impact and noise when a valve body is seated in a valve drive device of an internal combustion engine. .

[0002]

2. Description of the Related Art In an internal combustion engine, intake of air and air-fuel mixture into a cylinder and discharge of exhaust air to the outside of the cylinder are performed by a valve element provided in a cylinder head. Conventionally, opening and closing of the valve element has been performed by a cam that is rotationally driven by a crankshaft. However, recently, a valve drive device has been proposed in which the timing and speed of valve opening and closing can be freely set regardless of the shape and rotational speed of the cam.

FIG. 2 shows a configuration of a linear actuator type valve drive device as a conventional example of such a valve drive device.
FIG. 3 is a perspective view of a linear actuator type valve drive device. The linear actuator 10 shown in these figures is
It is composed of a stator 30 and a mover 12. The stator 30 has three pole pieces 34, 35, 36 of electromagnets on the end surface of the yoke 31, and these are arranged side by side along the length direction of the mover 12. The mover 12 includes a yoke 32 and a magnetic pole piece 34, which are magnetic path members different from the yoke 31.
It is provided in the gap 33 between 35 and 36, and is indicated by arrow A in the figure.
Alternatively, it can reciprocate in the B direction.

As shown in FIG. 3, there is a locking hole 14 at the tip of the mover 12, into which a cylindrical locking portion 13 at the rear end of the valve body 11 is fitted, so that the mover 12 can move. And the valve body 11 are connected. Therefore, when the mover 12 moves, the valve body 11 can be moved to the valve closing position or the valve opening position.

The mover 12 is provided with two through-holes, and the through-hole has a thickness substantially the same as the plate thickness of the mover 12.
Two permanent magnets 21 and 22 are fitted. The upper and lower surfaces of the fitted permanent magnets 21, 22 are substantially flush with the upper and lower surfaces of the mover 12.

Adjacent end faces of the permanent magnets 21 and 22 have opposite magnetic poles. That is, as shown in FIG. 2, the yoke 31 side of the permanent magnet 21 is magnetized to the N pole and the yoke 32 side is magnetized to the S pole, and the yoke 3 of the permanent magnet 22 is magnetized.
One side is magnetized to the S pole and the yoke 32 side is magnetized to the N pole.

The core 3 is provided in the central portion around which the yoke 31 orbits.
7, a fixed frame 23 made of a non-magnetic material such as resin is provided around the core 37. Fixed frame 2
An electromagnetic coil 38 is wound around the side wall of the coil 3 so as to surround the core 37. A magnetic gap 39 is provided between the upper end of the core 37 and the yoke 31. Also,
The electromagnetic coil 38 is connected to a power source (not shown),
The power supply supplies a drive current having a polarity corresponding to either the valve closing direction or the valve opening direction of the valve body 11 to the electromagnetic coil 38.

When no current is supplied to the electromagnetic coil 38, the magnetic resistance of the magnetic gap 39 is large with respect to the magnetic force of the permanent magnets 21 and 22. Therefore, the N pole of the permanent magnet 21 → the pole piece 34 → Yoke 31 → Pole piece 36 → S pole of permanent magnet 22 → N pole of permanent magnet 22 → Yoke 32 →
A magnetic path that revolves like the S pole of the permanent magnet 21 and the permanent magnet 2
The permanent magnet 21 is formed such that a magnetic path that revolves like the N pole of 1 → the pole piece 35 → the S pole of the permanent magnet 22 → the N pole of the permanent magnet 22 → the yoke 32 → the S pole of the permanent magnet 21. , 2
2 is positioned at a predetermined position (hereinafter referred to as a reference position) together with the mover 12.

On the other hand, when a current is supplied to the electromagnetic coil 38, magnetic flux is generated inside the core 37, and this magnetic flux is distributed in the yoke 31 and the magnetic pole pieces 34, 35, 36.
A magnetic pole is generated on each surface of the magnetic field, and a magnetic field is formed in the above-mentioned magnetic field region. The polarities of the magnetic poles generated in the magnetic pole pieces 34 and 36 are the same, and the polarities of the magnetic poles generated in the magnetic pole piece 35 are different from the polarities of the magnetic poles generated in the magnetic pole pieces 34 and 36. For example, when a direct current flowing in a predetermined direction is supplied to the electromagnetic coil 38, the magnetic pole pieces 34 and 3
6 has an S pole, and the pole piece 35 has an N pole. In addition, a direct current in the direction opposite to the predetermined direction is applied to the electromagnetic coil 38.
, The magnetic pole pieces 34 and 36 have N poles, and the magnetic pole piece 35 has S poles.

When the S pole is generated in the magnetic pole pieces 34 and 36 and the N pole is generated in the magnetic pole piece 35, the N pole of the permanent magnet 21 is generated.
Pole → Pole piece 34 → Yoke 31 → Magnetic gap 39 → Core 37 → Pole piece 35 → S pole of permanent magnet 22 → Permanent magnet 22
Of the permanent magnets 21 and 22 so that a magnetic path revolving with the N pole of the magnet → the yoke 32 → the S pole of the permanent magnet 21 is newly formed.
According to the magnitude of the magnetic flux density generated in the core 37, it moves in the direction of arrow A shown in FIG.

On the other hand, an N pole is generated in the pole pieces 34 and 36,
When the S pole is generated in the pole piece 35, the permanent magnet 2
N pole of 1 → pole piece 35 → core 37 → magnetic gap 39 →
The yoke 31 → the magnetic pole piece 36 → the S pole of the permanent magnet 22 → the N pole of the permanent magnet 22 → the yoke 32 → the S pole of the permanent magnet 21.
2 moves along with the mover 12 in the direction of arrow B according to the magnitude of the magnetic flux density generated in the core 37, and opens the valve.

As described above, when the current is not supplied to the electromagnetic coil 38, the valve body 11 can be positioned at the reference position, and the direction of the current supplied to the electromagnetic coil 38 is changed so that the mover 12 is moved. Can be moved in the direction A or the direction B, and the valve body 11 can be positioned in the valve closing position or the valve opening position.

When a direct current flowing in the reverse direction is supplied, the magnitude of the driving force has a negative value and the driving force is in the opposite direction. By configuring the device as described above, it is possible to obtain a stable driving force regardless of the positions of the permanent magnets 21 and 22 that are the movable members.

FIG. 4 is a view showing a state in which the linear actuator is attached to the cylinder head of the internal combustion engine. The linear actuator 10 shown here is one in which the stator 30 and the yoke 32 shown in FIGS. 2 and 3 are integrated into one frame.

The linear actuator 10 has a mounting portion 1
Nos. 0a and 10b are provided in a protruding manner, and these are superposed on the mounting seats 20a and 20b provided on the cylinder head 20, and are tightened and fixed by bolts 15 and 16.
At this time, the valve body 11 is attached to the valve seat 20c so that it can come into contact with and separate from the valve seat 20c.

The mounting portions 10a and 10b and the mounting seat 20
Although a and 20b are shown only at two places in FIG. 4, there are actually the same hidden positions in a direction (thickness direction) perpendicular to the paper surface of the linear actuator 10, and a total of four places. It is fixed.

[0017]

In the valve drive device using the linear actuator having the above-described structure, the valve body 11 has the valve seat 2
When seated at 0c, both the valve body 11 and the valve seat 20c are impacted, or an impact sound is generated when seated.

Measures for mitigating such impact and reducing impact noise have been proposed in the electromagnetically driven valve of Japanese Patent Laid-Open No. 2000-8817. This is because the movable magnet is fixed to the armature shaft that is displaced together with the valve body, and when the valve body reaches the valve closing side and the valve opening side, the fixed magnet is arranged so as to be adjacent to this movable magnet and fixed to the movable magnet. The opposite magnetic poles of the magnet have the same polarity. With this configuration, when the valve body reaches the valve closing position or valve opening position, the movable magnet approaches the fixed magnet, and the repulsive force due to the same polarity brakes the valve body's movement, reducing impact and impact noise. You can do it.

However, according to this structure, since the movable magnet is fixed to the movable portion, there is a problem that the mass of the movable portion increases and the responsiveness of opening and closing the valve element deteriorates. In addition, since the movable magnet is a circular plate shape and the fixed magnet is an annular shape in which the movable magnet can be loosely fitted, there is a limit in the capacity as a damper,
There is also a problem that a sufficient shock absorbing effect cannot be obtained.

The present invention solves these problems, and an object thereof is to provide a support structure for a linear actuator which can obtain a sufficient shock absorbing effect without increasing the mass of the movable part. There is.

[0021]

In order to achieve the above object, a support structure for a linear actuator according to the present invention comprises a stator and a mover which is linearly driven forward and backward by the stator. In a support structure of a linear actuator for fixing a stator to a base material, the stator is supported on the base material at a plurality of positions in a movable state parallel to the moving direction of the mover, and the base material of each support portion. It is characterized in that permanent magnets are provided on the side and the stator side, and the facing surfaces of these magnets have the same polarity.

Further, in each of the supporting portions, the base material side and the stator side are connected by a rod in a state where the stator side is movable, and the magnet is inserted through the rod, or the linear actuator is In the valve drive device for an internal combustion engine, a valve element may be attached to the mover.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a linear actuator support structure according to the present invention. The linear actuator 10 shown in the figure has almost the same configuration as that described in the conventional example, and therefore the different points will be mainly described.

The linear actuator 10 includes mounting seats 20a, 20 formed on a cylinder head 20 as a base material.
It is attached to b. The mounting portions 10d and 10e of the linear actuator 10 are slightly thinner than the mounting portions 10a and 10b of the conventional example. And bolts 15 and 16
Instead, the rods 17 and 18 are attached to the mounting seats 20a and 20b. The rods 17 and 18 are movable elements 12
It is parallel to the moving direction of. Also, the rods 17, 18
Has a structure similar to that of a hexagonal bolt, but has a flat round bar portion without a male screw between the head and the male screw portion at the tip. Then, in this round bar portion, a disk-shaped permanent magnet 25, 26 or a permanent magnet 27, 2 having a hole in the center is formed.
8 is inserted. The permanent magnets 25 and 26 or 27 and 28 inserted into the rods 17 and 18 have the same polarities on the surfaces facing each other.

Due to the above-mentioned structure, the linear actuator 10 has the permanent magnets 25 and 26 or the permanent magnets 27 and 2.
Due to the repulsive force of 8, the gap d is maintained and is supported in a floating state. This is called a floating support structure here. In FIG. 1, two pairs of permanent magnets 25, 26 and 27, 2
Although only eight are shown, there is the same hidden position in the thickness direction of the linear actuator 10 (direction orthogonal to the advancing / retreating direction of the valve body 11), and it is floatingly supported by a total of four pairs of magnets. Become.

When the linear actuator 10 is operated to reciprocate the mover 12 with the above-described structure, when the valve body 11 is seated on the valve seat 20c, the linear actuator 10 itself moves a little distance in the direction of the arrow in FIG. Come to do. The movement of the linear actuator 10 receives a repulsive force by four pairs of magnets such as the permanent magnets 25, 26 and 27, 28. This repulsive force is generated by the permanent magnets 25, 26 and 27,
Since 28 becomes larger as it approaches 28, the impact of the valve body 11 sitting on the valve seat 20c is absorbed, and the impact noise is also alleviated.

In the above structure, the rods 17 and 18 are fixed to the cylinder head 20 side. However, if the linear actuator 10 can be supported so as to move forward and backward, the rods 17 and 18 can be moved.
May be fixed to the linear actuator 10 side, and the cylinder head 20 and the rods 17 and 18 may be slidable. Furthermore, a floating support structure is used for the rod 1.
It is also possible to use a structure other than 7, 18 such as a cylinder and a piston.

[0028]

As described above, the present invention supports a linear actuator having a stator and a mover which is linearly moved forward and backward by the stator and fixes the stator to a base material. In the structure, the stator is supported on the base material at a plurality of positions in a movable state in parallel with the moving direction of the mover, and permanent magnets are provided on the base material side and the stator side of each supporting portion, Since the facing surfaces of these magnets have the same polarity, when the mover moves, the linear actuator itself can slightly move in the moving direction of the mover to absorb the shock. Therefore, the impact applied to the mover and the stator can be mitigated.

If the linear actuator is a valve drive device for an internal combustion engine and the movable element is provided with a valve element, the impact noise when the valve of the internal combustion engine is seated on the valve seat can be reduced. .

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a support structure for a linear actuator according to the present invention.

FIG. 2 is a diagram showing a basic configuration of a conventional linear actuator valve drive device.

3 is a perspective view of the linear actuator type valve drive device of FIG. 2. FIG.

FIG. 4 is a diagram showing a state in which the linear actuator of FIG. 2 is attached to a cylinder head of an internal combustion engine.

[Explanation of symbols]

10 Linear actuator 12 mover 17,18 rod 20 Base material 25,26,27,28 Permanent magnet 30 stator

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 3G018 AB09 CA14 DA37 DA40 DA41                       DA42 DA44 DA83 DA85 FA06                       FA07 GA02 GA03 GA31 GA32                 5H633 BB08 GG02 GG04 GG05 GG09                       HH03 HH05 HH08 HH11 HH13                       HH15 HH22 HH26 HH29 JA04                       JB03

Claims (3)

[Claims] 1. A support structure for a linear actuator, comprising: a stator; and a mover that is linearly driven forward and backward by the stator, wherein the stator is fixed to a base material. The support is supported on the base material at a plurality of positions in a state that it can move back and forth in parallel with the moving direction of the base material, and permanent magnets are provided on the base material side and the stator side of each support part, and the facing surfaces of these magnets have the same polarity. A support structure for a linear actuator characterized in that 2. In each of the support portions, the base material side and the stator side are connected by a rod in a state where the stator side is movable, and the magnet is inserted through the rod. A support structure for the linear actuator described. 3. The linear actuator support structure according to claim 1, wherein the linear actuator is a valve drive device for an internal combustion engine, and a valve element is attached to the mover.