JP2006166607A - Linear motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To embody a linear motor that is small in size but yet has such a structure that high thrust can be generated and can be used as an actuator for directly driving the intake or exhaust valve of an engine by electromagnetic force. <P>SOLUTION: A pair of electromagnets, each constructed of a core formed of laminated steel plates and a coil wound around the core, are provided opposite to each other. Moving members having a permanent magnet are disposed between a pair of the electromagnets, disposed opposite to each other, with gaps between them and the respective electromagnets. The moving elements are relatively moved with a pair of the electromagnets used as a stator. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motor, and more particularly to a linear motor that can be used as an actuator that directly drives an intake or exhaust valve of an engine with an electromagnetic force.

  A linear motor is a motor that moves linearly, is also called a linear motor, and is generally used to drive an object on a straight line. Recently, the application of the linear motor to a super-high-speed railway has been studied.

  Some linear motors having a narrow movable range directly drive an intake or exhaust valve of an engine with electromagnetic force (see Patent Documents 1 and 2 described later).

  The linear motor having a narrow movable range is used not only for the engine valve control device described above but also for a fine movement stage of a processing / measuring machine, a robot, or the like. At this time, such a linear motor is required to be small in size, generate a large thrust, and to be capable of high-speed operation. In practice, the operation is limited to a movable range, and the structure is simple. It is also needed.

  In particular, when a linear motor is used in an engine valve control device whose basic operation is a reciprocating operation, the performance emphasized as a large thrust force, a large deceleration force or the like changes depending on the operation state.

JP 2000-199411 A JP 2000-303660 A JP 2001-351812 A JP 2002-238241 A JP 2002-303660 A Japanese Utility Model Publication No. 7-29952

  Incidentally, in the conventional linear motor 502, as shown in FIG. 45, two electromagnets 512 and 514 each made up of a core 508 made of laminated steel plates and a coil 510 wound around the core 508 are connected to form a stator 504. In some cases, a movable element 506 made up of, for example, a single layer of permanent magnets 516 is provided on the stator 504.

  When the conventional linear motor described above is used as an actuator for directly driving an intake or exhaust valve of an engine with electromagnetic force, the engine 602 includes a cylinder block 604 and an upper surface of the cylinder block 604 as shown in FIG. The cylinder head 606 is mounted, a head cover (not shown) that covers the upper portion of the cylinder head 606, and an oil pan (not shown) mounted on the lower surface of the cylinder block 604.

  The cylinder block 604, the cylinder head 606, and the piston 608 form a combustion chamber 610, and an intake port 612 and an exhaust port 614 that communicate with the combustion chamber 610 are formed in the cylinder head 606.

  An intake valve 616 for opening and closing the downstream end of the intake port 612 is provided, and an exhaust valve 618 for opening and closing the upstream end of the exhaust port 614 is provided.

  At this time, when the exhaust valve 618 is opened by the actuator 620, a driving force that overcomes the in-cylinder pressure generated in the combustion chamber 610 in FIG. 47 is required (see FIG. 46).

  Regarding the volume ratio driving force, particularly at full load, the in-cylinder pressure may be about 4 to 5 bar depending on the combustion gas even if the piston falls to the bottom dead center. In order to obtain a driving force required for opening the exhaust valve, the coil of the actuator is enlarged to cope with it, and there is a disadvantage that the size is increased.

  On the other hand, regarding the layout, the size of the actuator has limitations such as cylinder pitch and engine height.

  That is, the linear motion type engine 702 will be described. As shown in FIGS. 48 and 49, the engine 702 includes a cylinder block 704, a cylinder head 706 mounted on the upper surface of the cylinder block 704, and an upper portion of the cylinder head. A head cover (not shown) for covering and an oil pan (not shown) attached to the lower surface of the cylinder block 704 are provided.

  A combustion chamber 710 is formed by the cylinder block 704, the cylinder head 706, and a piston (not shown), and an intake port 712 and an exhaust port 714 communicating with the combustion chamber 710 are formed in the cylinder head 706, and the intake port An intake valve 716 that opens and closes the downstream end of 712 is provided, and an exhaust valve 718 that opens and closes the upstream end of the exhaust port 714 is provided.

  Further, a fuel injection injector 722 is disposed in the intake port 712, a spark plug 724 is mounted on the combustion chamber 712 on the upper surface portion, and an intake linear motor electromagnetic system is attached to the end of the valve stem 726 of the intake valve 716. An actuator 728 is provided, and an exhaust linear motor electromagnetic actuator 732 is provided at the end of the valve stem 730 of the exhaust valve 718.

  Reference numeral 734 denotes an exhaust side stem guide, 736 denotes an exhaust side stem seal, and 738 denotes a mover of the exhaust linear motor type electromagnetic actuator 732.

  At this time, in the case of a direct acting type engine, particularly in the case of the exhaust linear motor type electromagnetic actuator, a hydraulic system is not required and the system is a simple system, but the exhaust valve is connected to the end of the valve stem of the exhaust valve. Since the linear motor type electromagnetic actuator is directly arranged, it has a direct influence on the engine package, and the exhaust side requires a driving force, so that the actuator width exceeds the cylinder pitch (see FIG. 49). There is a disadvantage that the degree of freedom in layout is low and it is difficult to mount the engine.

  Further, with respect to lift controllability, there is an inconvenience that the valve does not operate at the intended lift curve as shown in FIG. 55 due to individual differences of the actuators and engine conditions.

  Therefore, in order to eliminate the above-mentioned inconveniences, the present invention provides a pair of electromagnets composed of a core made of laminated steel sheets and a coil wound around the core facing each other, and between each pair of electromagnets disposed facing each other. A mover provided with a permanent magnet is disposed through a gap with the electromagnet, and the mover moves relative to each other using a pair of electromagnets as a stator.

  As described above in detail, according to the present invention, a pair of electromagnets composed of a core made of laminated steel sheets and a coil wound around the core are provided facing each other, and each of the pair of electromagnets provided facing each other is provided. A mover having a permanent magnet is disposed between a pair of electromagnets by arranging a mover having a permanent magnet through a gap between the electromagnet and the pair of electromagnets as a stator. Since it is provided, the length of the pair of electromagnets in the moving direction of the mover can be shortened.

  By inventing as described above, a pair of electromagnets composed of a core made of laminated steel sheets and a coil wound around the core are made to face each other, and each pair of electromagnets provided facing each other is permanent through each electromagnet and a gap. A mover equipped with a magnet is arranged, a pair of electromagnets is used as a stator, a linear motor is configured so that the mover moves relative to each other, and the length of the pair of electromagnets in the moving direction of the mover is shortened. .

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  1 to 20 show a first embodiment of the present invention. In FIG. 1, 2 is a linear motor, 4 is a stator, and 6 is a mover.

  The linear motor 2 is provided with a pair of electromagnets 12 and 14 including a core 8 made of laminated steel plates and a coil 10 wound around the core 8, and a pair of electromagnets 12 provided to face each other. , 14 is arranged between the electromagnets 12, 14 and the permanent magnet 16 with a gap S therebetween, and the pair of electromagnets 12, 14 is connected to the stator 4, that is, the first stator 4A and the first stator. As the two stators 4B, the movable element 6 is configured to relatively move.

For reference, the difference between the in-cylinder pressure (Pcyl) and the exhaust port internal pressure (Pport) is required, for example, when the exhaust valve on the exhaust side is opened, for the conventional inconvenience related to the volume ratio driving force and layout. Driving force approximately proportional to pressure and valve umbrella area (Avalve), that is, thrust F (i) = Avalve · (Pcyl (i) −Pport (i)) + fmis
However, the maximum required driving force is the moment when the valve is opened. Therefore, the thrust of the linear motor should be designed high at the initial position.

  On the contrary, since a large thrust is not required after the lift is started, the positional relationship between the permanent magnet arranged on the mover and the core is adjacent in the initial state (valve closed).

  In addition, FIG. 1 shows an actuator configuration using the linear motor 2 that has the maximum thrust in the initial valve opening period of 0 to 0.3 Hf (Hf: full lift amount), and shows the initial (closed) position. ing. The thrust is highest when the end of the core 8 and the mover 6 provided with the permanent magnet 16 are arranged side by side.

  Further, since the lift control requires high accuracy for the inconvenience related to the lift controllability, the search coil loop can be efficiently arranged in a place where the magnetic flux density is high as shown in FIGS. Since it is necessary, it was arranged so as to be orthogonal to the magnetic path crossing between the opposing coils.

  In an embodiment of the present invention, in order to suppress the height of the actuator unit using the linear motor 2, the stator 4, which is a pair of electromagnets 12 and 14, that is, the first stator 4A and the second stator 4B are provided. The movable element 6 (in the case of an engine, an intake / exhaust valve) is opposed to both sides (also referred to as “opposite”), and there may be one or two movable elements 6.

  The first embodiment is intended to provide an actuator unit that is small in size, has a large thrust, and can be operated at high speed.

The first embodiment is divided as follows.
(1) Example 1-1 (a) Example 1-1-1 (see FIGS. 4 and 5)
(A) Example 1-1-2 (see FIGS. 6 and 7)
(C) 1-1-3 embodiment (see FIGS. 8 to 11)
(2) 1-2 Example (a) 1-2-1 Example (See FIGS. 14 and 15)
(A) 1-2-2 embodiment (see FIGS. 16 and 17)
(3) 1-3 Example (a) 1-3-1 Example (See FIGS. 18 and 19)
(A) 1-3-2 embodiment (see FIGS. 20 and 21)
(4) First to fourth embodiments (see FIGS. 22 to 24)

  In the above-mentioned (1) 1-1 embodiment, permanent magnets are arranged between opposing electromagnets, and the permanent magnets are of a single layer type and are made as thick as possible.

  The (1) 1-1-1 embodiment of the (1) 1-1 embodiment is a one-layer type.

  That is, (1) the 1-1st embodiment (a) The 1-1-1 embodiment is a pair of electromagnets 12-1a, 14-1a as shown in FIG. 1a and 2nd stator 4B-1a are provided facing each other, and between these 1st stator 4A-1a and 2nd stator 4B-1a, each 1st stator 4A-1a and 2nd stator 4B are provided. -1a and a single layer of the movable element 6-1a having a permanent magnet 16-1a are arranged via a gap S-1a, and the movable element 6-1a is relatively moved.

  FIG. 5 discloses the relationship between the force (Force) and the position (Position) of the linear motor in the (1) 1-1-1 embodiment (a) 1-1-1 embodiment.

  In addition, (1) (1-1) Example 1-1 of Example 1-1 is a one-layer type, and (1) Example 1-1 of Example 1-1 above (1) 1-1 The magnet width is narrower than that disclosed in the example.

  That is, (1) (1-1) Example 1-1 of Example 1-1 is the same as (1) 1-1-1 Example of (1) 1-1 Example above. Similarly to FIG. 6, the first stator 4A-1b and the second stator 4B-1b, which are a pair of electromagnets 12-1b and 14-1b, are provided to face each other, and these first stators are provided. The movable element including the permanent magnet 16-1b between the first stator 4A-1b and the second stator 4B-1b and the gap S-1b between the 4A-1b and the second stator 4B-1b. 6-1b is arranged, and the mover 6-1b is configured to move relative to each other, and the magnet width W-1b of the mover 6-1b is set to (1) (A) of the first to first embodiments. ) Narrower than the magnet width W-1a of the mover 6-1a of the 1-1-1 embodiment.

  And when arrange | positioning the said 1-layered movable element 6-1b provided with the permanent magnet 16-1b between 1st stator 4A-1b and 2nd stator 4B-1b, as shown in FIG. The mover 6 in which the magnet width W-1b is narrower than the magnet width W-1a of the mover 6-1a of the above-mentioned (1) 1-1 embodiment described above. 1b is arranged.

  FIG. 7 discloses the relationship between the force (Force) and the position (Position) of the linear motor in (1) 1-1-1 embodiment (1) 1-1-2 embodiment.

  When the magnet width of the mover provided with a permanent magnet is reduced, the mover is disclosed in (1) 1-1-1 embodiment (c) 1-1-3 embodiment. Can be two layers.

  That is, as shown in FIGS. 8 to 10, a two-layer movable element 6 </ b> A− including a permanent magnet 16 </ b> A- 1 b and a permanent magnet 16 </ b> B- 1 b between the first stator 4 </ b> A- 1 b and the second stator 4 </ b> B- 1 b. 1b and the mover 6B-1b, and a central core 24-1b divided into three parts between the two movers 6A-1b and 6B-1b are arranged.

  When the mover of the type shown in FIG. 8 is used, an initial driving force of 250 N is obtained within 3 ms when a current 25A is passed.

  In the case where the type of mover shown in FIG. 9 is used, an initial driving force of 288 N can be obtained within 3 ms when a current 25 A is passed.

  FIG. 11 shows the force and position of the linear motor when the mover has two layers in (1) 1-1-1 embodiment (c) 1-1-3 embodiment. Disclose the relationship.

  The above-described (2) 1-2 example relates to the winding method of the coil, and is wound around the core 8-2 having the core teeth 18-2 provided along the permanent magnet 16-2. The coil 10-2 is wound around the core teeth 18-2 without a gap.

  And (a) 1-2-1 embodiment of (2) 1-2 embodiment is a type in which the coil is wound around the entire space without a gap.

  That is, (2) the 1-2th embodiment (a) The 1-2-1 embodiment is a pair of electromagnets 12-2a, 14-2a as shown in FIG. 2a and the second stator 4B-2a are provided to face each other, and the first stator 4A-2a and the second stator 4B are provided between the first stator 4A-2a and the second stator 4B-2a, respectively. -2a and a two-layer movable element 6A-2a and a movable element 6B-2a provided with a permanent magnet 16A-2a and a permanent magnet 16B-2a through a gap S-2a, and the two movable elements 6A-2a, 6B -2a and a central core 24-2a divided into three, and the two-layer movable element 6A-2a and movable element 6B-2a move relative to each other, and the coils 10A-2a, Wrap 10B-2a around the entire space without any gaps. Thereby, it can be expected that the magnetic flux is prevented from passing directly between the core teeth (without passing through the core) and the thrust reduction is suppressed.

  In general, in a linear motor, in a region surrounded by a core tooth, a permanent magnet 16A-2a, and a permanent magnet 16B-2a, in a portion close to the permanent magnet 16A-2a and the permanent magnet 16B-2a. Since the coil is not wound, the core teeth 18A-2a are obtained when the number of turns is the same in the (2) 1-2-1 embodiment (a) 1-2-1 embodiment. , 18B-2a, the permanent magnets 16A-2a and the permanent magnets 16B-2a, the coils 10A-2a and 10B-2a are uniformly wound around the entire region.

  FIG. 13 discloses the relationship between the force (Force) and the position (Position) of the linear motor in (2) the 1-2th embodiment of (2) the 1-2-1 embodiment.

  Further, (2) Example 1-2 of Example 1-2 is a type that operates in the reverse direction with respect to FIG.

  That is, (2) (1-2) Example 1-2-2 of Example 1-2 is the first stator 4A-, which is a pair of electromagnets 12-2b, 14-2b, as shown in FIG. 2b and the second stator 4B-2b are provided to face each other, and the first stator 4A-2b and the second stator 4B are provided between the first stator 4A-2b and the second stator 4B-2b, respectively. -2b and the two-layer movable element 6A-2b and the movable element 6B-2b having the permanent magnet 16A-2b and the permanent magnet 16B-2b through the gap S-2b, and the two movable elements 6A-2b, 6B -B is arranged between the central core 24-2b and the movable cores 6A-2b and 6B-2b of the two layers move relative to each other, and the core teeth 18A-2b 18B-2b, permanent magnet 16A-2b and permanent magnet 16B-2b Region surrounded by the coil 10A-2b, wound 10B-2b, a configuration to fill the gap.

  FIG. 15 discloses the relationship between the force (Force) and the position (Position) of the linear motor in the (2) 1-2-2 embodiment of the (2) 1-2-2 embodiment.

  The above (3) 1-3 example relates to the shape of the tip of the core tooth 18-3 of the pair of electromagnets 12-3, 14-3.

  The (3) 1-3rd embodiment (A) 1-3-1 embodiment shows a base shape.

  That is, (3) the first to third embodiments, (a) the first to third embodiments, as shown in FIG. 16, are a pair of electromagnets 12-3a and 14-3a. 3a and the second stator 4B-3a are provided to face each other, and between the first stator 4A-3a and the second stator 4B-3a, the first stator 4A-3a and the second stator 4B, respectively. -3a and two layers of mover 6A-3a and mover 6B-3a provided with permanent magnet 16A-3a and permanent magnet 16B-3a through a gap (not shown), and the two movers 6A-3a The central core 24-3a divided into three is arranged between 6B-3a, and the two-layer movable element 6A-3a and the movable element 6B-3a are configured to move relative to each other, and a pair of electromagnets 1st stator 4A-3a and 2nd fixation which are 12-3a and 14-3a Core teeth 18A-3a of 4B-3a, the 18B-3a the leading edge shape based shape.

  When the mover of the type shown in FIG. 16 is used, an initial driving force of 230 N can be obtained within 3 ms when a current of 25 A is supplied.

  In addition, (3) the 1-3rd embodiment of (3) the 1-3rd embodiment is (a) the tip shape of the core tooth 18-3b is different from the 1-3-1 embodiment. The configuration has a sharp shape.

  That is, (3) the first to third embodiments (a) in the first to third embodiment, the first stator 4A- is a pair of electromagnets 12-3b and 14-3b as shown in FIG. 3b and the second stator 4B-3b are provided to face each other, and the first stator 4A-3b and the second stator 4B are provided between the first stator 4A-3b and the second stator 4B-3b, respectively. -3b and a two-layer movable element 6A-3b and a movable element 6B-3b provided with a permanent magnet 16A-3b and a permanent magnet 16B-3b through a gap (not shown), and the two movable elements 6A-3b , 6B-3b, and a central core 24-3b divided into three, and the two-layer movable element 6A-3b and the movable element 6B-3b move relative to each other, and the core teeth The tip shapes of 18A-3b and 18B-3b are sharpened.

  In other words, the tips of the core teeth 18A-3b and 18B-3b are sharpened, and the total number of turns is increased while maintaining the number of turns per unit area for the vacant space.

  In the case where the type of mover shown in FIG. 17 is used, an initial driving force of 280 N is obtained within 3 ms when a current 25A is passed.

  In the above (4) 1-4 embodiment, the shape of the tip of the core teeth 18-4b of the pair of electromagnets 12-4, 14-4 and the operating direction of the mover 6A-4 and the mover 6B-4 are shown. It is about relationships.

  That is, (4) in the first to fourth embodiments, as shown in FIG. 18, the first stator 4A-4 and the second stator 4B-4, which are a pair of electromagnets 12-4 and 14-4, are opposed to each other. The permanent magnet is provided between the first stator 4A-4 and the second stator 4B-4 via the first stator 4A-4 and the second stator 4B-4 and the gap S-4. The two-layer movable element 6A-4 and the movable element 6B-4 having 16A-4 and the permanent magnet 16B-4, and the central core 24 divided into three parts between the two movable elements 6A-4 and 6B-4 -4 is arranged, and the two-layer movable element 6A-4 and movable element 6B-4 are configured to move relative to each other.

  In addition, the core of the electromagnet is a passage through which magnetic flux flows, and a sufficient width is required to achieve high thrust, and it is necessary to make the core thinner for miniaturization. In order to obtain a high thrust without depending on the operation direction, it is necessary to make the width of the core equal to the left and right. For example, when used for valve driving of a vehicle engine, particularly when driving in a specific direction, When high thrust is required, the width of the core at one end may be made larger than the width of the core at the other end (not shown).

  And in the above-mentioned (4) 1-4th Example, the width of the core of both ends is made equal, without changing the sum of the width of the core of both ends.

  FIG. 19 discloses the relationship between the force (Force) and the position (Position) of the linear motor in the (4) 1-4th embodiment.

  FIG. 20 discloses a summary of the relationship between the force and position of the linear motor in the first embodiment described above and third and fourth embodiments described later.

  In each example in the first embodiment described above, the linear motor can be used for driving the intake or exhaust valve of the vehicle engine.

  That is, an actuator unit composed of a linear motor is provided at the end of a valve stem of an intake valve and exhaust valve (not shown), and the intake valve and exhaust valve are opened and closed by this actuator unit.

  Next, the operation will be described.

  The permanent magnet 16 of the mover 6 has one of the polarities of the N pole and the S pole on the upper side in FIG. 1, and has the other polarity on the lower side in FIG.

  In the cores 8A and 8B around which the coils 10A and 10B of the pair of electromagnets 12 and 14 that become the stator 4 are wound, when no current is applied to the pair of electromagnets 12 and 14, the permanent magnet 16 is The provided mover 6 is stopped at a predetermined position, that is, a reference position.

  When a current is applied to the pair of electromagnets 12 and 14, magnetic flux is generated inside the cores 8A and 8B, and this magnetic flux is distributed in the electromagnets 12 and 14 and the core teeth 18Aa at the upper and lower ends of the cores 8A and 8B. Magnetic poles are generated on the surfaces of the 18Ac, 18Ba, 18Bc and the core teeth 18Ab, 18Bb at the central portion, and a magnetic field is formed in the magnetic field region.

  At this time, the polarities of the magnetic poles generated in the core teeth 18Aa, 18Ac, 18Ba, 18Bc at the upper and lower ends of the core 8 are the same polarity, and the polarities of the magnetic poles generated in the core teeth 18Ac, 18Bc at the central portion of the cores 8A, 8B are The polarity of the magnetic poles generated in the core teeth 18Aa, 18Ab, 18Ba, 18Bb at the upper and lower ends of the cores 8A, 8B is different.

  For example, when a current is applied to the pair of electromagnets 12 and 14 so that the thrust direction is a specific direction, S poles are generated in the core teeth 18Aa, 18Ac, 18Ba, and 18Bc at the upper and lower ends of the cores 8A and 8B. N poles are generated in the core teeth 18Ab and 18Bb at the center portion of the eight.

  Further, when a current is applied to the pair of electromagnets 12 and 14 so that the thrust directions are reversed, N poles are generated in the core teeth 18Aa, 18Ac, 18Ba, and 18Bc at the upper and lower ends of the cores 8A and 8B. An S pole is generated in the core teeth 18Ab and 18Bb in the central portion of the core.

  By applying a current to the pair of electromagnets 12 and 14, magnetic poles are generated in the core teeth 18Aa, 18Ac, 18Ba, 18Bc at the upper and lower ends of the cores 8A, 8B and the core teeth 18Ab, 18Bb in the central portion of the cores 8A, 8B, and the permanent The mover 6 moves in a specific direction which is a thrust direction depending on the polarity of the mover 6 provided with the magnet 16.

  When current is applied to the pair of electromagnets 12 and 14 so that the thrust directions are reversed, the core teeth 18Aa, 18Ac, 18Ba, 18Bc at the upper and lower ends of the cores 8A, 8B and the core teeth 18Ab at the central portion of the cores 8A, 8B , 18Bb, opposite magnetic poles are generated, and the mover 6 moves in a direction opposite to a specific direction which is a thrust direction by the polarity with the mover 6 provided with the permanent magnet 16.

  As a result, a pair of electromagnets 12 and 14 composed of a core 8 made of laminated steel sheets and a coil 10 wound around the core 8 are provided facing each other, and between the pair of electromagnets 12 and 14 provided facing each other. The electromagnets 12 and 14 and the movable element 6 including the permanent magnets 16 are disposed through the gap S, and the pair of electromagnets 12 and 14 is the stator 4, that is, the first stator 4A and the second stator 4B. The mover 6 is provided with a permanent magnet 16 between a pair of electromagnets 12 and 14 by the linear motor 2 configured to move relative to the mover 6. The length of the pair of electromagnets 12 and 14 in the direction can be shortened.

  In addition, the coil wound around the core provided with the core teeth provided along the permanent magnet is wound without gaps on the inner side of the core teeth. The static thrust can be increased even when the number of turns is larger than when there is a gap. Moreover, the flow of magnetic flux can be organized.

  Furthermore, since the tip shape of the core tooth has a sharp shape, the space for winding the coil increases, so the number of coil turns can be increased, so the maximum thrust can be increased without changing the outer dimensions. It is possible to make it.

  Furthermore, in the first embodiment of the present invention, a pair of electromagnets 12 and 14 composed of a core 8 made of laminated steel plates and a coil 10 wound around the core 8 are provided facing each other and provided facing each other. The movable element 6 including the permanent magnet 16 is disposed between the pair of electromagnets 12 and 14 via the respective electromagnets 12 and 14 and the gap S, and the pair of electromagnets 12 and 14 is the stator 4, that is, the first. As the stator 4A and the second stator 4B, the linear motor 2 configured so that the movable element 6 relatively moves can suppress the height of an actuator unit that uses the linear motor, and the vehicle engine. When used for driving the intake and exhaust valves, the height of the drive device can be kept low, and the height of the engine and the engine hood can be kept down.

  Moreover, in the above-mentioned (1) 1-1 Example, the permanent magnet 16-1 is arrange | positioned between the electromagnets 12-1 and 14-1 which oppose, and the permanent magnet 16-1 is a 1 layer type, and thickness is set. By making it as thick as possible, the permanent magnet 16-1 is a one-layer type, so the structure is simple and the thrust can be improved if the thickness of the permanent magnet 16-1 is increased. is there.

  Further, in the above (2) 1-2 embodiment, the coil 10-2 wound around the core 8-2 having the core teeth 18-2 provided along the permanent magnet 16-2 is replaced with the core 10-2. By winding the teeth 18-2 on the inner side without any gaps, the static thrust can be increased even when there is a gap even with the same number of turns.

  Furthermore, in the above-mentioned (3) 1-3 example, since the tip of the core teeth 18-3 of the pair of electromagnets 12-3, 14-3 is sharp, the space for winding the coil is increased. The number of coil turns can be increased, and the maximum thrust can be increased without changing the outer dimensions.

  In the above-mentioned (4) 1-4 embodiment, the mover is related to the relationship between the core teeth of the pair of electromagnets 12-4 and 14-4 and the operating directions of the mover 6A-4 and the mover 6B-4. When a high thrust is required only when driving the motor in a specific direction, it is only necessary to make one core tooth thicker than the other, so it is possible to improve the problem that conflicts with downsizing in a balanced manner. It is.

  21 to 38 show a second embodiment of the present invention. In the second embodiment, portions that perform the same functions as those of the first embodiment will be described with the same reference numerals.

  The feature of the second embodiment is that it relates to the shape and arrangement of the electromagnet for limiting the operating range of the mover to the set range.

The second embodiment is divided as follows.
(1) Example 2-1 (a) Example 2-1-1 (see FIGS. 21 to 28)
(A) Example 2-1-2 (see FIGS. 29 and 30)
(C) Example 2-1-3 (see FIGS. 31 and 32)
(2) Example 2-2 (see FIGS. 33 to 38)

  In the above-mentioned (1) 2-1 embodiment, the end portion of the core of the electromagnet is shaved, and at least one of the gaps between the end portion of the core tooth located outside the movable range of the permanent magnet and the mover. The part has a configuration that is longer than the gap between the core teeth and the mover within the movable range of the permanent magnet.

  The (1) Example 2-1 of Example 2-1 is for cutting the left side portion of the core of the electromagnet to such an extent that no thrust is generated, and is provided between the permanent magnets. This is a type in which up to 6 mm is left from the left side of the core located on the rightmost side of the central core divided into three.

  That is, (1) Example 2-1 of (a) Example 1-1-1 is a pair of electromagnets 112-1a and 114-1a as shown in FIGS. 21, 23, 25, and 27. The first stator 104A-1a and the second stator 104B-1a, which are the first stator 104A-1a and the second stator 104B-1a, are arranged to face each other, and the first stator 104B-1a is provided between the first stator 104A-1a and the second stator 104B-1a. 104A-1a and the second stator 104B-1a and the two layers of the movable elements 106A-1a and 106B-1a provided with permanent magnets 116A-1a and 116B-1a via the gap S-1a are arranged. The movable elements 106A-1a and 106B-1a have a structure in which the movable elements 106A-1a and 106B-1a move relative to each other, and the electromagnet 112- located in a portion not facing the permanent magnets 116A-1a and 116B-1a provided on the movable elements 106A-1a and 106B-1a. 1 , 114-1a cores 108A-1a and 108B-1a, and the core tooth ends located outside the movable range of the permanent magnets 116A-1a and 116B-1a and the movers 106A-1a and 106B-1a Is formed longer than the gap between the core teeth in the movable range of the permanent magnets 116A-1a and 116B-1a and the movers 106A-1a and 106B-1a.

  In addition, what is disclosed in FIG. 21 is that of the electromagnets 112-1a and 114-1a that are not opposed to the permanent magnets 116A-1a and 116B-1a provided on the movers 106A-1a and 106B-1a. The cores 108A-1a and 108B-1a are cut to the left to form cutting parts 122A-1a and 122B-1a, and the electromagnet is divided into three central cores arranged between the permanent magnets 116A-1a and 116B-1a, respectively. The leftmost core on the rightmost side of 124-1a is shaved from the left side to 6mm, and current is applied to the electromagnets 112-1a and 114-1a so as to move the movers 106A-1a and 106B-1a in the right direction of FIG. It is a state of being applied.

  In FIG. 22, (1) in the type of the second-first embodiment (a) in the type that is left up to 6 mm from the left side of the second-first embodiment, the movers 106A-1a, 106B in the right direction of FIG. The relationship between the force (Force) and the position (Position) of the linear motor in a state where current is applied to the electromagnets 112-1a and 114-1a so as to move -1a is disclosed.

  What is disclosed in FIG. 23 is (1) of the 2-1 embodiment (a) in the 2-1-1 embodiment, the central core 124-divided into three electromagnets provided between the permanent magnets. In addition to the type that is left up to 10 mm from the left side of the core located on the rightmost side of 1a, the electromagnets 112-1a and 114-1a have currents that move the movers 106A-1a and 106B-1a in the right direction of FIG. In a state where is applied.

  In FIG. 24, in the type (1) of the 2-1 embodiment (a) 10 mm from the left side of the 2-1-1 embodiment, the movers 106A-1a and 106B are arranged in the right direction of FIG. The relationship between the force (Force) and the position (Position) of the linear motor in a state where current is applied to the electromagnets 112-1a and 114-1a so as to move -1a is disclosed.

  In the type disclosed in FIG. 25, (1) in the second-first embodiment (a) in the type that is left up to 6 mm from the left side of the second-1-1 embodiment, the current is applied so that the thrust direction is reversed. This is the case when it is applied.

  FIG. 26 shows a state in which a current is applied so that the thrust direction is reversed in the type (1) of the 2-1 embodiment (a) the type left from the left side of the 2-1-1 embodiment up to 6 mm. The relationship between the force (Force) and the position (Position) of the linear motor is disclosed.

  What is disclosed in FIG. 27 is (1) the case of the 2-1 embodiment (a) in addition to the structure of the 2-1-1 embodiment, in which no current is applied.

  FIG. 28 shows the force of the linear motor in a state in which no current is applied in the type (1) of the 2-1 embodiment (a) in the type that is left up to 6 mm from the left side of the 2-1-1 embodiment. The relationship between (Force) and position (Position) is disclosed.

  (1) Example 2-1 of Example 2-1) Example 2-1-2 is intended to scrape the right portion of the core of the electromagnet to such an extent that no thrust is generated.

  That is, (1) of the 2-1 embodiment (a) In the 2-1-2 embodiment, as shown in FIG. 29, the first stator 104A- is a pair of electromagnets 112-1b, 114-1b. 1b and the second stator 104B-1b are provided to face each other, and the first stator 104A-1b and the second stator 104B are provided between the first stator 104A-1b and the second stator 104B-1b, respectively. -1b and two layers of movers 106A-1b and 106B-1b having permanent magnets 116A-1b and 116B-1b through a gap S-1b and the two movers 106A-1b and 106B-1b A central core 124-1 b divided into three is disposed between the movable elements 106 A-1 b and 106 B-1 b, and the cores 108 A-1 b of the electromagnets 112-1 b and 114-1 b have a configuration in which the movable elements 106 A- 1 b and 106 B- 1 b move relative to each other. 10 The right portion of B-1b is cut to such an extent that no thrust is generated to form cutting portions 122A-1b and 122B-1b, and 6 mm from the left side of the rightmost core of the three-divided central core 124-1b. It is what was left and sharpened.

  FIG. 30 discloses the relationship between the force (Force) and the position (Position) of the linear motor in (1) the (2-1) second-1-2th embodiment.

  (1) (2-1) Example of Example 2-1 The example of Example 2-1-3 cuts both side portions of the core of the electromagnet to such an extent that no thrust is generated.

  That is, (1) of the 2-1 embodiment (c) In the 2-1-3 embodiment, as shown in FIG. 31, the first stator 104A- is a pair of electromagnets 112-1c, 114-1c. 1c and the second stator 104B-1c are provided to face each other, and the first stator 104A-1c and the second stator 104B are provided between the first stator 104A-1c and the second stator 104B-1c, respectively. -1c and two layers of movers 106A-1c and 106B-1c having permanent magnets 116A-1c and 116B-1c through a gap S-1c, and the two movers 106A-1c and 106B-1c A central core 124-1 c divided into three is disposed between the movable elements 106 A-1 c and 106 B-1 c, and the cores 108 A-1 c of the electromagnets 112-1 c and 114-1 c have a configuration in which the movable elements 106 A- 1 c and 106 B- 1 c move relative to each other. 10 Cutting both sides of B-1c to such an extent that no thrust is generated to form cutting parts 122Aa-1c, 122Ab-1c, 122Ba-1c, 122Bb-1c, and the rightmost side of the three-divided central core 124-1c The left side of the core located at is left to 6 mm.

  FIG. 32 discloses the relationship between the force (Force) and the position (Position) of the linear motor in the (1) 2-1 embodiment (c) 2-1-3 embodiment.

  (2) In the 2-2 embodiment, a permanent magnet is arranged instead of the core of the electromagnet provided between the permanent magnets deleted in the above-described (1) 2-1 embodiment.

  That is, (2) in the 2-2 embodiment, as shown in FIG. 33, the first stator 104A-2 and the second stator 104B-2 which are a pair of electromagnets 112-2 and 114-2 are opposed to each other. The permanent magnet is provided between the first stator 104A-2 and the second stator 104B-2 via the first stator 104A-2 and the second stator 104B-2 and the gap S-2. Two layers of the movable elements 106A-2 and 106B-2 provided with 116A-2 and 116B-2 are arranged, and the movable elements 106A-2 and 106B-2 are configured to move relative to each other. (1) Instead of the core located in the rightmost side of the three-way divided central core 124-2 of the electromagnet provided between the permanent magnets 116A-2 and 116B-2, which is deleted in the 2-1 embodiment, A permanent magnet 126-2 is disposed.

  FIG. 34 discloses the relationship between the force (Force) and the position (Position) of the linear motor in the (2) 2-2 embodiment.

  FIG. 35 shows the above-described first embodiment, (1) the (2-1) embodiment of (2-1) the above-mentioned first embodiment, and (2) the second-2-2 embodiment. The total of the relationship between the force (Force) and the position (Position) of the linear motor is disclosed.

  FIG. 36 shows the force and position of the linear motor in the first embodiment described above and (1) (2-1) the second-1-1 embodiment. Disclose the aggregated relationships.

  FIG. 37 includes the first embodiment described above, (1) the (2-1) embodiment of (2-1) the second-1-2 embodiment, and (1) the (2-1) embodiment of (2-1). 2-1-3 Disclosed is a summary of the relationship between the force and position of the linear motor in the embodiment.

  FIG. 38 shows the above-described first embodiment, (1) the (2-1) embodiment (a) the 2-1-2 embodiment, and (1) the 2-1 embodiment (c) 2-1-3 Disclosed is a summary of the relationship between the force and position of the linear motor in the embodiment.

  In other words, in the second embodiment, a pair of electromagnets 112 and 114 each including a core 108 made of laminated steel plates and a coil 110 wound around the core 108 are provided to face each other. The movable element 106 having the permanent magnet 116 is disposed between the pair of electromagnets 112 and 114 via the respective electromagnets 112 and 114 and the gap S, and the pair of electromagnets 112 and 114 is fixed to the stator 104, that is, the first fixed. As the child 104A and the second stator 104B, the linear motor 102 is configured such that the movable element 106 moves relative to the permanent magnet between the pair of electromagnets 112 and 114 as in the first embodiment. Since the movable element 106 including the movable element 106 is provided, the length of the pair of electromagnets 112 and 114 in the movable direction of the movable element 106 is shortened. It is those that can be.

  In addition, at least a part of the gap between the end portion of the core tooth located outside the movable range of the permanent magnet and the mover is longer than the gap between the core tooth and the mover within the movable range of the permanent magnet. Thus, it is possible to keep the mover within the specified operating range.

  Furthermore, in the above-mentioned (1) 2-1 embodiment, in order to keep the mover within the specified operating range by scraping the core of the electromagnet in the portion not facing the permanent magnet provided on the mover. In addition, it is effective to delete the core of the electromagnet that extends to a portion that does not face the permanent magnet or to have a shape that does not exert influence.

  Furthermore, in the above-mentioned (2) 2-2 embodiment, (1) instead of the electromagnet core provided between the permanent magnets deleted in the 2-1 embodiment, a permanent magnet is arranged. Therefore, it can be installed so that the repulsive force works with the mover, and it is possible to increase the working range and working force.

  39 and 40 show a third embodiment of the present invention.

  The feature of the third embodiment is that the cross-sectional shape of the coil is rectangular.

  That is, as shown in FIG. 39, the first stator 204A and the second stator 204B, which are a pair of electromagnets 212 and 214, are provided facing each other, and between the first stator 204A and the second stator 204B, 3 between the two movable elements 206A and 206B and the two movable elements 206A and 206B having permanent magnets 216A and 216B with a gap S between the first stator 204A and the second stator 204B. The divided central core 224 is disposed, and the movers 206A and 206B move relative to each other. The coils 210A and 210B wound around the cores 208A and 208B constituting the pair of electromagnets 212 and 214 are arranged. The cross-sectional shape is rectangular.

  FIG. 40 discloses the relationship between the force and position of the linear motor in the third embodiment.

  Then, by making the cross-sectional shape of the coils 210A and 210B rectangular, that is, rectangular, the cross-sectional shapes of the electromagnets 212 and 214 surrounding the coils 210A and 210B can be made rectangular. It is possible to simplify the shape of the first stator 204A and the second stator 204B composed of 214, and thus the linear motor, which can be easily manufactured, and there is no gap in the rectangular electromagnets 212 and 214. The coils 210A and 210B can be wound, and the static thrust can be increased as compared with the case where there is a gap.

  41 and 42 show a fourth embodiment of the present invention.

  The feature of the fourth embodiment is that the thrust / movable part mass ratio is improved more than the absolute value of the thrust.

  That is, as shown in FIG. 41, the first stator 304A and the second stator 304B, which are a pair of electromagnets 312, 314, are provided to face each other, and between the first stator 304A and the second stator 304B, Between each of the first and second stators 304A and 304B and the two movable elements 306A and 306B, there are three layers between the two movable elements 306A and 306B and the two movable elements 306A and 306B provided with permanent magnets 316A and 316B through a gap S. The divided central core 324 is disposed, and the movable elements 306A and 306B move relative to each other. The distance between the surfaces of the permanent magnets 316A and 316B in the right direction is constant, and the width (moving part moving direction) is set. Is to shorten.

  FIG. 42 discloses the relationship between the force (Force) and the position (Position) of the linear motor in the fourth embodiment.

  Then, the thrust / movable part mass ratio can be improved more than the absolute value of the thrust, which is practically advantageous.

  As another measure of the fourth embodiment, the width of the permanent magnet can be set to approximately half of the movable range of the mover.

  Then, the flow of magnetic flux can be improved, the magnetic resistance is small, and the permeance coefficient is large.

  And by increasing the permeance coefficient, the heat resistance can be improved, the weight can be reduced, and the thrust / movable part mass ratio can be improved.

  43 and 44 show a fifth embodiment of the present invention.

  The feature of the fifth embodiment relates to the shape and arrangement of a search coil as a sensor.

  At this time, the core 408 includes core teeth 418 provided along a permanent magnet (not shown), and a search coil 428 is provided on the core teeth 418.

  That is, the search coils are arranged so as to be parallel to the moving direction of the mover, and are arranged so that lines having different current flowing directions do not come close to each other.

  Further, the search coil is arranged in a portion near the tip of the surface of the mover facing the stator of the laminated steel plate.

The fifth embodiment is divided as follows.
(1) Example 5-1 (see FIG. 43)
(2) Example 5-2 (see FIG. 44)

  That is, (1) in the 5-1th embodiment, as shown in FIGS. 43A, 43B, and 43C, a plurality of, for example, four search coils 428a-1, 428b-1, 428c-1 are provided. 428d-1 is formed into a film shape and attached to the mover, that is, the core 408.

  At this time, as shown in FIGS. 43A, 43B, and 43C, the centers of the four search coils 428a-1, 428b-1, 428c-1, and 428d-1 are shifted in the moving direction while the core Arrange them so that they overlap (including the air core).

  In this case, the magnetic flux density change is large and the sensitivity is increased. In addition, the distance between the lines in which the current flows in different directions can be secured sufficiently, and interference can be suppressed.

  In the above-mentioned (2) 5-2 embodiment, as shown in FIGS. 44 (a), (b), and (c), a plurality of, for example, four search coils 428a-2, 428b-2, 428c. -2, 428d-2 are formed into a film and embedded in the mover, that is, the core 408.

  At this time, as shown in FIGS. 44A, 44B, and 44C, the four search coil cores (including air cores) are arranged so as not to overlap.

  Then, it has the effect that the change in magnetic flux density is large and the sensitivity is increased, and the distance between the lines in which the current flows in different directions can be taken sufficiently, and it can be configured in a planar pattern, facilitating manufacture. It is.

  Further, other than the (1) 5-1 embodiment and (2) 5-2 embodiment of the fifth embodiment described above, a search coil arrangement policy is conceivable.

  In other words, there are a policy for increasing the sensitivity by arranging the search coil near the sharp tip and increasing the change in magnetic flux density, and a policy for improving the impression by providing a core in the core of the search coil.

  The present invention is not limited to the first to fifth embodiments described above, and various application modifications can be made.

  For example, in the embodiment of the present invention, the stator is formed by making a pair of electromagnets face each other. However, a special configuration in which three or more electromagnets are arranged to form a stator is also possible. .

  That is, in a plan view, three or more electromagnets are arranged on the outer peripheral portion of the mover provided with permanent magnets, for example, at equal intervals around the circumference to form a stator.

  In this case, when the stator is formed by arranging four electromagnets, the four electromagnets are arranged in a cross shape on the outer peripheral portion of the mover provided with the permanent magnet in a plan view. is there.

  Then, it can contribute to shortening the length of the electromagnet in the movable direction of the mover, and the stator composed of three or more electromagnets acts on the mover, so that the mover can be operated reliably. It can also contribute to the improvement of reliability.

  Further, in the embodiment of the present invention, when the stator is formed by making a pair of electromagnets face each other, the arrangement position of the mover in the movable direction is set to the same position. It is also possible to have a special configuration that makes it different.

  That is, when a linear motor formed by a mover and a mover is used for driving an intake or exhaust valve of a vehicle engine, the layout around the valve stem of the intake or exhaust valve is limited. Therefore, the length of the movable element in the movable direction is changed for each electromagnet.

  In this case, it is possible to cope with the restriction of the layout around the valve stem of the intake or exhaust valve while maintaining the function of the stator made of the electromagnet.

  Furthermore, in the embodiment of the present invention, it is possible to adopt a special configuration in which the above-described policy of arranging three or more electromagnets to be a stator and the policy of making electromagnets arranged differently are used together. is there.

It is a principal part enlarged view of the linear motor which shows 1st Example of this invention. It is an enlarged view of the arrow II part of FIG. It is a figure which shows the driving force substantially proportional to the differential pressure | voltage of the cylinder pressure and exhaust port internal pressure in valve opening of the exhaust valve of an exhaust side. It is a general | schematic enlarged block diagram of a linear motor. It is a figure which shows the relationship between the force (Force) of a linear motor, and a position (Position). It is a general | schematic enlarged block diagram of a linear motor. It is a figure which shows the relationship between the force (Force) of a linear motor, and a position (Position). It is a schematic layout diagram of a linear motor. It is a schematic block diagram of a linear motor. It is a general | schematic enlarged block diagram of a linear motor. It is a figure which shows the relationship between the force (Force) of a linear motor, and a position (Position). It is a general | schematic enlarged block diagram of a linear motor. It is a figure which shows the relationship between the force (Force) of a linear motor, and a position (Position). It is a general | schematic enlarged block diagram of a linear motor. It is a figure which shows the relationship between the force (Force) of a linear motor, and a position (Position). It is a schematic block diagram of a linear motor. It is a schematic block diagram of a linear motor. It is a general | schematic enlarged block diagram of a linear motor. It is a figure which shows the relationship between the force (Force) of a linear motor, and a position (Position). It is a figure which shows the relationship between the force (Force) of a linear motor and the position (Position) which totaled each example relevant to this 1st Example. It is a general | schematic enlarged block diagram of the linear motor which shows 2nd Example of this invention. It is a figure which shows the relationship between the force (Force) of a linear motor, and a position (Position). It is a general | schematic enlarged block diagram of a linear motor. It is a figure which shows the relationship between the force (Force) of a linear motor, and a position (Position). It is a general | schematic enlarged block diagram of a linear motor. It is a figure which shows the relationship between the force (Force) of a linear motor, and a position (Position). It is a general | schematic enlarged block diagram of a linear motor. It is a figure which shows the relationship between the force (Force) of a linear motor, and a position (Position). It is a general | schematic enlarged block diagram of a linear motor. It is a figure which shows the relationship between the force (Force) of a linear motor, and a position (Position). It is a general | schematic enlarged block diagram of a linear motor. It is a figure which shows the relationship between the force (Force) of a linear motor, and a position (Position). It is a general | schematic enlarged block diagram of a linear motor. It is a figure which shows the relationship between the force (Force) of a linear motor, and a position (Position). It is a figure which shows the relationship between the force (Force) of a linear motor and the position (Position) which totaled each example relevant to this 2nd Example. It is a figure which shows the relationship between the force (Force) of a linear motor and the position (Position) which totaled each example relevant to this 2nd Example. It is a figure which shows the relationship between the force (Force) of a linear motor and the position (Position) which totaled each example relevant to this 2nd Example. It is a figure which shows the relationship between the force (Force) of a linear motor and the position (Position) which totaled each example relevant to this 2nd Example. It is a general | schematic enlarged block diagram of the linear motor which shows 3rd Example of this invention. It is a figure which shows the relationship between the force (Force) of a linear motor, and a position (Position). It is a general | schematic enlarged block diagram of the linear motor which shows 4th Example of this invention. It is a figure which shows the relationship between the force (Force) of a linear motor, and a position (Position). FIG. 6 shows a sixth embodiment of the present invention, in which (a) is a plan view of a mover of a laminated steel plate on which four search coils formed in a film shape are attached, and (b) is four search operations formed in a film shape. The side view of the needle | mover of the laminated steel plate which affixed the coil, (c) is a principal part enlarged view of the part which affixed the search coil to the needle | mover of a laminated steel plate. The other example in 6th Example of this invention is shown, (a) is a top view of the needle | mover of the laminated steel plate which embedded four search coils shape | molded in the film form, (b) is 4 formed in the film form. The side view of the needle | mover of the laminated steel plate which embed | buried each search coil, (c) is the principal part enlarged view of the part which embed | buried the search coil in the needle | mover of the laminated steel plate. It is a schematic block diagram of the linear motor which shows the 1st prior art of this invention. It is a figure which shows the in-cylinder pressure waveform at the time of using the linear motor which shows the 2nd prior art of this invention as an actuator which drives the intake or exhaust valve of an engine with an electromagnetic force directly. It is the schematic of an engine at the time of using a linear motor as an actuator which drives an intake or exhaust valve of an engine with direct electromagnetic force. It is a schematic sectional drawing of the linear motion type engine which shows the 3rd prior art of this invention. It is a schematic plan view of a linear motion type engine. It is a figure which shows the lift curve in the lift controllability which shows the 4th prior art of this invention.

Explanation of symbols

2 linear motor 4 stator 4A first stator 4B second stator 6 mover 8 core 10 coil 12, 14 pair of electromagnets 16 permanent magnets

Claims (8)

  A pair of electromagnets comprising a core made of laminated steel sheets and a coil wound around the core are provided facing each other, and a mover provided with permanent magnets between each pair of electromagnets provided facing each other with a gap between each electromagnet And a pair of electromagnets as a stator, and the mover moves relative to each other.   The linear motor according to claim 1, wherein a coil wound around a core having core teeth provided along the permanent magnet is wound without any gap on the inside of the core teeth.   The linear motor according to claim 2, wherein a tip shape of the core tooth has a sharp shape.   At least a part of a gap between the end portion of the core tooth located outside the movable range of the permanent magnet and the mover is longer than a gap between the core tooth located within the movable range of the permanent magnet and the mover. The linear motor according to claim 1.   The linear motor according to claim 1, wherein the width of the permanent magnet is set to approximately half of the movable range of the mover.   The linear motor according to claim 1, wherein the core includes core teeth provided along a permanent magnet, and a search coil is provided on the core teeth.   The linear motor according to claim 1, wherein the linear motor is used for driving an intake or exhaust valve of a vehicle engine. A pair of electromagnets comprising a core made of a laminated steel plate and a coil wound around the core are provided opposite to each other, and a central core divided into three is provided at a central portion between the pair of electromagnets, and the pair of electromagnets and the central core The linear motor according to claim 1, wherein a mover having a permanent magnet is respectively disposed between the pair of electromagnets and the central core, and the mover moves relative to each other. .

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