JP5433963B2 - Linear actuator - Google Patents

Description

  The present invention relates to a linear actuator, and in particular, but not limited to, a linear reciprocating motion.

  In the long history, various types of linear actuators have been presented.

As an example of a simple actuator, there is a solenoid, and an armature moves corresponding to an electric coil. Actuators such as solenoids are used in a variety of applications from small to large, from home to industrial. (For example, see Patent Document 1)
JP 2003-70226 A

  However, although various linear actuator technologies are known, there are various obstacles in performance as an important point in design.

  A problem with conventional linear actuators is limited thrust for a given size. For applications that require a large thrust, a large linear actuator is required. Although a large linear actuator can be applied in many applications, a linear actuator having a minimum size is desirable for applications in which downsizing of the product is required as a whole. This problem can be dealt with by increasing the coil size and current. However, problems such as increased power consumption and increased heat generation occur. In many applications, it is desirable to maximize efficiency and minimize heat generation.

  Another problem of conventional linear actuators such as solenoids is that uniform thrust over the entire stroke cannot be obtained. Generally, the thrust is maximized at the center of the stroke where the electromagnetic force is maximized. The thrust decreases as the stroke ends. The fact that the thrust fluctuates in the movable range usually has to be matched to the minimum thrust and will determine the size of the linear actuator for a given application.

  Further, the thrust / stroke nonlinearity characteristic of the conventional linear actuator cannot be precisely positioned.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a linear actuator that is small in size, high in efficiency, low in heat generation, and capable of obtaining a uniform thrust over the entire stroke.

In order to solve the above-described problem, the invention according to claim 1 includes a coil member and a movable member that can reciprocate, and the movable member has a reciprocating shaft, and is spaced apart along the shaft. The first magnet and the second magnet magnetized in opposite directions, and the magnets arranged between the first magnet and the second magnet are magnetized in different directions from the first magnet and the second magnet. and a third magnet, the coil members have a first coil and a second coil which is arranged and coaxially apart along said axis, said coil member, said first and said The core further includes a second coil, and the core includes a first coil and a first coil extending between the second coil and an end of the core adjacent to the movable member. A gap and a second gap are formed, The movable member is arranged to move between a maximum position in the first direction and a maximum position in the second direction, and the first position of the third magnet is at the maximum position in the first direction. When the end on the direction side is at the maximum position in the second direction, the end on the second direction side of the third magnet is between the first gap and the second gap. Align with the core part .

  According to a second aspect of the present invention, the movable member is magnetized in a direction opposite to the shaft, the first magnet magnetized in the radial direction of the shaft, and the first magnet. And the second magnet.

  According to a third aspect of the present invention, the first magnet, the second magnet, and the third magnet are arranged adjacent to each other in series in parallel to the axis of the movable member. It is characterized by.

  According to a fourth aspect of the present invention, the first magnet, the second magnet, and the third magnet extend in a circumferential direction of the movable member.

  The invention according to claim 5 is characterized in that the shaft is made of a magnetic material.

  In the invention according to claim 6, the shaft is made of a non-magnetic material, and the first magnet, the second magnet, and the third magnet are installed in a circumferential direction of the shaft. It is characterized by that.

The invention according to claim 7 is arranged such that the movable member moves between a maximum position in the first direction and a maximum position in the second direction, and the maximum position in the first direction is In an initial position intermediate between the maximum position in the second direction, the first magnet is disposed to face the first coil, and the second magnet is opposed to the second coil. It is characterized by being arranged.

According to a ninth aspect of the present invention, the first coil and the second coil are configured to receive a current, and the current is a first current in order to move the movable member in the first direction. When flowing in a polarity and moving in a second direction opposite to the first direction, the current flows in a second polarity opposite to the first polarity.

The invention according to claim 10 is characterized in that a non-magnetic member is interposed between the coil member and the movable member.

The invention according to claim 11 is characterized in that the non-magnetic member has a sleeve extending in a longitudinal direction of movement of the movable member.

The invention described in claim 12 is characterized in that a gap is provided between the movable member and the non-magnetic member.

According to a thirteenth aspect of the present invention, an armature and a first coil and a second coil surrounding the armature are provided, and the armatures are disposed along the armature and are opposite to each other. Having a first magnet and a second magnet magnetized in the radial direction of the armature with a polarity of a third magnet, and a third magnet disposed between the first magnet and the second magnet. The first coil and the second coil are housed in a core, and the core includes the first coil, the second coil, and an end of the core adjacent to the armature. Chi lifting the first gap and second gap respectively extending between said armature between the first maximum position and the first direction direction the second direction of the maximum position in the The first magnet of the third magnet is configured to move and at a maximum position in the first direction. The end on the opposite side is aligned between the first gap and the second gap at the maximum position in the second direction. The end on the second direction side of the third magnet is aligned between the first gap and the second gap. , characterized in that.

The invention according to claim 14 is characterized in that at least one adjacent portion of the first magnet, the third magnet, and the second magnet and the third magnet has a tapered shape. To do.

The invention described in claim 15 is characterized in that the number of magnets of the movable member is three and the number of coils of the coil member is two.

  In the first aspect of the present invention to be disclosed, the linear actuator includes a coil and a movable member that reciprocates. The movable member has first and second linearly movable shafts and opposite polarities. The first and second coils are disposed between the first magnet and the first and second magnets. The first and second coils are disposed coaxially with the movable shaft. The first and second magnets are magnetized so that the magnetic field strength on the magnet surface adjacent to the coil is increased and the magnetic field strength on the magnet surface adjacent to the reciprocating member is decreased. Consideration is given so that the magnetic field strength of the magnet can be maximized at the circumference of the reciprocating member to which the magnet is joined.

  Accordingly, the lines of magnetic force generated from the first, second, and third magnets interact with the lines of magnetic force generated by the currents to the respective coils. A current flowing in one direction in one coil and in the opposite direction in the other coil acts to move the movable member and the magnet in the first direction. On the other hand, when a current in the opposite direction to the first and second coils is passed, the first and second coils act to move in the direction opposite to the first direction. If no current is applied, the magnet and the movable member remain stationary. Therefore, the movement of the magnet and the movable member can be controlled by applying an electric current.

  In effect, the three magnets are arranged according to a Halbach magnet pattern arranged such that the magnetic field strength on the first side is increased and the magnetic field strength on the other side is increased. This magnet arrangement greatly reduces the magnetic field strength on one side and increases the magnetic field strength on the opposite side. The advantage of using this magnet arrangement is that the magnetic flux lines on the opposite side to which the magnets are attached can be reduced, so that the amount of iron armature or iron-backed armature required by conventional linear actuators can be reduced or eliminated. I can do it. Similarly, the magnetic field strength on the side close to the coil is enhanced, and the thrust increases when the following description is applied to a linear actuator.

  The magnet is arranged on the movable member that reciprocates in a structure suitable for the size and shape of the movable member. For example, the magnets are arranged in a ring shape so that a uniform magnetic field is generated in the diameter direction on the cylindrical shaft. In addition or as a modification, the magnet is embedded in a reciprocating movable member for the purpose of protecting the magnet and reducing the overall size. In addition or as a modification, it is divided and arranged in one or several lines around the circumference of the movable member that reciprocates in parallel with the movable direction.

  For example, four hullback array magnets can be arranged on the circumference in 90 ° divisions. This can reduce the weight of the member.

  In the present invention, various arrangements within the range of the Halbach array magnet can be utilized as necessary.

  The magnet itself is selected from optimum materials, and for example, a neodymium magnet (NDFEB), a summary cobalt magnet (SMCO) or a ferrite magnet can be used. Other optimal magnet materials can also be used.

  This magnet arrangement does not require an iron material, that is, a movable member that reciprocates heavily, as in the prior art, that is, a lightweight design using a material other than the iron material is possible. An appropriate material can be selected according to the application of the linear actuator. For example, the weight can be significantly reduced by using a non-metal such as resin as the material of the movable member that reciprocates. Furthermore, reducing the weight of the movable part leads to a reduction in inertia of the movable member.

  The shape and size of the reciprocating movable member is determined by the application and the desired movement that the linear actuator produces. As an example, the reciprocating movable member may be a cylinder or a real axis along the central axis of the coil. In such an arrangement, the magnetization direction of the first magnet is a direction spreading outward with respect to the axial center, and the second magnet has the opposite polarity. The third magnet is installed between the first and second magnets, and the magnetization direction is a direction from one magnet toward another magnet. Each magnet can be placed away if the hullback effect is increased.

  The magnets are moderately placed around or along the axis of the reciprocating movable member. The magnet can be a cylindrical magnet in order to have a uniform magnetic field strength. The magnetic field strength on the magnet surface increases due to the hullback effect.

  The coil is arranged so that it can work in cooperation with the magnetic flux of the three magnets. The interaction of the magnetic field lines by the two coils and magnets minimizes flux fluctuations in the core and in the reciprocating movable member during the entire stroke. This increases the efficiency of the linear actuator and minimizes power consumption, and importantly minimizes the generation and release of heat in the movable member that reciprocates within the core.

  The coil may be disposed so as to surround the movable member portion that reciprocates. Preferably, however, the movable member that reciprocates around the center of the coil is arranged to move. The combination of this arrangement and the three magnets described before extending around the shaft maximizes the thrust generated in the linear actuator.

  The arrangement of the coils has an iron core shape in which the first and second coils are housed in the core and has a central axis corresponding to the movable axis of the movable member. The two coils are placed at an optimal distance according to the specific requirements of the linear actuator, the core material, the coil winding density, etc. Similarly, the size of the coil and the size of the core surrounding the coil are selected according to the required specifications of the linear actuator.

  The core surrounding the coil bridges or concentrates the magnetic field along the magnet coupled to the coil and to the reciprocating movable member. In order to prevent short-circuiting of the magnetic flux in the core, i.e. to prevent the magnetic flux lines that circulate only in the core, the core may have two gaps or a core material that extends to the end of the core adjacent to the movable member that reciprocates with the coil. Discontinuous. In effect, the cross section of the core is E-shaped with two gaps adjacent to a reciprocating movable member and a hullback array magnet coupled thereto.

  The size of each gap is determined by the core material, coil placement, and current factors, and is therefore determined by the linear actuator requirements. However, the minimum gap length is set to the minimum value that prevents magnetic saturation at a given operating current. The gap itself is filled with a material that protects the air gap or coil. However, the material needs to prevent a magnetic short circuit.

  The linear actuator can be set to have an optimal length of linear actuation or stroke. The stroke forms a first portion from the midpoint position to the maximum stroke in the first direction, and forms a second portion of the maximum stroke from the midpoint to the second direction in the reverse direction. . Conveniently, in order to increase the magnetic field intensity over the full stroke, the midpoint position of the third magnet corresponds to the intermediate position of the coil arrangement. That is, the third magnet is in an intermediate position along the movable direction of the first and second coils. That is, the thrust generated by the coupling of the magnetic field lines of the coil and the magnetic field lines of the first magnet and the second magnet is maximized in both directions. Details are described below.

  The stroke length in both directions is preferably chosen to keep the thrust constant and constant over the entire stroke. This is realized by restricting the movement so that the end of the third magnet is located between the gaps of the core described above. That is, the end of the third magnet does not overlap the gap in both directions of movement.

  As a characteristic of the Hullback arrangement, the magnetic field strength is small or a value toward zero at the end of the third magnet. If it extends to a position where the magnetic field strength becomes small, the coupling between the magnetic flux of the magnet and the coil decreases. As a result, the thrust of the linear actuator is reduced. By limiting the stroke of the linear actuator so that the portion where the magnetic flux line of the third magnet becomes smaller matches the core gap, the thrust can be maximized and the relationship between the stroke and the thrust can be made constant.

  The linear actuator has a wall (stopping the movement of the movable member) at the end of the movement of the movable member that reciprocates so that the end of the third magnet does not overlap the gap.

  The core material can be selected appropriately depending on the application of the linear actuator. For example, in the case of applying a low frequency current of 100 Hz or less, iron or other suitable material can be selected. In the case of applying a high frequency current of 100 Hz or more, an appropriate magnetic powder material is used.

  Although not described in detail here, the coil winding itself, including the coil manufacturing method, is performed using well-known techniques. The coil is driven by an AC power source, which is a conventional technique, and the two coils are connected in parallel or in series, and are connected to an optimum driving power source.

  The linear actuator is set to be movable in one direction, and the return to origin may be performed by other means such as a spring or gravity. Such an application may be used, for example, in an automobile brake. In such applications, the current is unidirectional. In reciprocating applications where bi-directional driving is required, the shaft is driven in a second direction opposite the first direction by a suitable alternating current.

  The reciprocating member is not limited and is set to move a piston, lever, cam, or other suitable member. The member itself is of course part of a complex component. For example, the linear actuator controls an automobile brake, an engine component, a speed reducer, a pump, and the like.

  In an example such as a refrigeration pipe of a refrigerator, the movable member is housed in a pipe. The linear actuator drives a refrigerator pump in the pressure pipe, and in such an application, the movable member is sealed from the coil and the core, where the coil, the core and the movable member are non-magnetic. For example, a sleeve or a suitable tube is used.

  It should be understood that the sleeve or tube contains a pressurized liquid, gas, and the movable member moves with them. The sleeve or tube can also have a guide that controls the direction of the stroke of the movable member. Appropriate gaps are provided between the outer periphery of the movable member and the inner periphery of the sleeve and cylinder. This gap or clearance may be wholly or partially filled with a suitable lubrication or low friction material.

  Looking at other requirements, the linear actuator has first and second coils, an electromagnetic induction member having an armature that moves along the movable axis of the linear actuator (ARMATURE), and the armature has a plurality of Halbach magnet configurations. Have a magnet.

  According to another requirement, the first and second coils surrounding the armature are provided, and the armature is magnetized in polarities opposite to each other in the circumferential direction installed along the armature. A magnet having a third polarity is provided between the first and second magnets and the first and second coils. The first and second coils are housed in a core having first and second gaps extending from the coil to the end of the core adjacent to the armature.

  Looking at other requirements, the mechanism provided in the linear actuator has a movable member that moves in first and second positions, and the movable member is connected to a reciprocating movable member of the linear actuator.

  Further, looking at other requirements, it has a core that surrounds the armature, and the armature is set to move along the axis of the core. The core has at least two coils wound coaxially with the core and connected in series, and the armature has a plurality of magnets having a hullback magnet configuration and extends in the longitudinal direction of the armature.

  The reciprocating member of the linear actuator moves in response to specific control signals that increase or decrease the coil current. For example, the control signal is a response to the target position of the movable member and / or the actual position of the movable member, that is, a closed loop.

  By making at least one adjacent portion of the first magnet and the third magnet and the second magnet and the third magnet into a tapered shape, the flow of magnetic flux becomes smooth, and the generated magnetic field can be increased. Therefore, the required thrust can be obtained by reducing the amount of the rare earth magnet.

  Further, the assembling work is facilitated by assembling the first magnet and the second magnet so that the third magnet is slid from both sides while utilizing the tapered shape.

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a cross section of a linear actuator 1 according to an embodiment of the present invention. The linear actuator 1 has a core 2 that houses two coils 3a (first coil) and 3b (second coil). The electric coil is formed in a ring shape by a conventional technique. Although not shown, the electrical connection to the coil is set to flow in opposite directions.

  The core 2 and the coils 3 a and 3 b are set so as to surround the central portion of the linear actuator 1 that extends thinly around the center of the coil and the core 2. The non-magnetic sleeve 4 is installed at the center of the core 2 and the linear actuator 1. Therefore, the core 2 and the central part are separated.

  The core 2 is made of an optimum material such as iron or a dust magnetic material. The material is selected according to the specific application of the linear actuator, for example, the desired stroke or load. The material is also selected depending on the frequency of the current flowing through the coils 3a and 3b.

  The sleeve 4 surrounds a reciprocating member or a movable mounting member coaxial with the center of the linear actuator 1. In this example, the movable member has a hollow shaft 5 and cylindrical magnets 6a (first magnet) and 6b (second magnet) coupled around the shaft 5 and magnetized in the radial direction. The shaft 5 is made of a magnetic material such as iron, but may be made of a nonmagnetic material such as stainless steel, aluminum, or resin. The magnets 6 a and 6 b are installed apart from each other along the axis 7 of the shaft 5. A third magnet 8 (third magnet) described below is installed in the middle of the two magnets 6a and 6b and is magnetized in the axial direction. The three magnets 6 a, 6 b, 8 are adjacent to each other along the surface of the shaft 5.

  The movable member moves between the maximum stroke position in the first direction (FIG. 7B) and the maximum stroke position in the second direction opposite to the first direction (FIG. 7C). Be placed. As shown in FIG. 7A, an intermediate position between the maximum stroke position in FIG. 7B and the maximum stroke position in FIG. 7C is set as the initial position. In the initial position, the magnet 6a is disposed to face the coil 3a, and the magnet 6b is disposed to face the coil 3b.

  The magnets 6a, 6b, 8 are joined to the shaft 5 in an optimum manner, i.e. by fitting or a suitable mechanical coupling method. In addition or as a variant, an adhesive is also used.

  In this example, the shaft 5 and the magnets 6 a, 6 b, 8 form a movable member or armature that moves along the axis 7. Appropriate gaps 11 are provided on the surfaces of the magnets 6 a, 6 b, 8 and the inside of the sleeve 4, so that they can move freely along the axis of the sleeve 4.

  The dimension of the sleeve 4 is determined by the application of the linear actuator 1. In a linear actuator 1 where the armature moves in a sealed or container environment, the sleeve 4 serves as the wall of the cylinder or pressure vessel. There is an example that works as a refrigerant circuit of a refrigerator. As an alternative or in addition, the sleeve 4 also serves as a guide for controlling the movement of the movable member.

  As shown in FIG. 1, the linear actuator 1 according to the present invention is compact and has a simple structure.

  FIG. 2 shows the positional relationship between the shaft 5 and the magnets 6a, 6b, and 8 on the shaft 5 in detail in a sectional view. As shown in FIG. 2, the three magnets 6 a, 6 b, 8 are arranged along the surface of the shaft 5. Three arrows indicate the polarities of the three magnets. When viewed from the left to the right, the first magnet 6 a is arranged in a direction in which the magnetic flux leaves the central axis 7 of the shaft 5. The second magnet 8 is arranged so that the magnetic flux is along the central axis 7 of the shaft 5, that is, from right to left. The third and last magnet is arranged so that the magnetic flux is directed toward the central axis 7 of the shaft 5. This arrangement of magnets is known as a hullback structure or a hullback arrangement. This magnet arrangement can take any number of magnets as long as the magnetization direction of each magnet is the correct angle with respect to the magnetization direction of the adjacent magnet. In this example, only three magnets are shown, but any combination can be taken in combination with the number of coils depending on the length of the shaft 5 and the desired stroke of the linear actuator 1.

  FIG. 3 shows the magnetic flux generated by the Halbach array magnet. As indicated by the arrows in FIG. 3, the magnetic flux increases on the upper side 9 of the hullback array and is weakened (substantially decreases) on the lower side 10. This arrangement not only increases the magnetic flux on the upper side 10 coupled with the coil, but also weakens the magnetic flux on the lower side 9 and can reduce or eliminate the amount of iron back yoke required in the conventional configuration. This is because the magnetic flux concentrates on the other side, and the opposite surface decreases the magnetic flux.

  FIG. 3 shows a portion where the magnetic flux is reduced. These are indicated by reference points A and B. The reference point A is a point of contact between the magnet 6a and the third magnet 8 and indicates the minimum amount of magnetic flux, and the reference point B is the magnet 6b and the third magnet. This is a point indicating the minimum amount of magnetic flux at 8 junction points. Such a point is a point where the direction of the magnetic flux changes, and becomes a value approaching zero with the minimum magnetic flux.

  FIG. 4 shows a different cross section of the linear actuator 1, in which the two coils 3 a, 3 b are housed in the core 2 and wound around the center of the linear actuator. When the hullback is arranged, the magnet is coupled to the shaft 5 and installed at the center of the linear actuator. The magnets 6 a, 6 b, 8 constituting the hullback array are separated from the sleeve 4 by a minute gap 11. The gap 11 freely moves the shaft and the hullback array magnets 6a, 6b, and 8 in the axial direction without interfering with each other.

  Of course, the gap 11 is not an essential requirement, and may be replaced with a suitable sliding material that moves the shaft 5 and the magnets 6a, 6b, and 8. Suitable materials may be, for example, PTFE coatings or other materials according to the application of the linear actuator.

  FIG. 5 is an explanatory diagram showing the optimum characteristics, cross-sectional dimensions, and hullback arrangement of the linear actuator 1 according to the present invention.

  FIG. 5A shows the optimum characteristics of the linear actuator according to the present invention. The stroke of the reciprocating movable member is indicated by -S and + S, and at this distance, the thrust is substantially constant. It is recognized that providing a constant thrust is particularly advantageous in the design range of the linear actuator 1.

  FIG. 5B is a cross-sectional view again, but shows specific dimensions. The dimension display of FIG.5 (b) is the following dimensions.

L ₁ Total length of the Hullback array movable member L ₂ Total length of the core along the movable direction of the reciprocating movable member C Distance between the outer end of the magnet (a) and the outer end of the stator core constituting the Hullback array A Distance between the outer end of the magnet (a) and the outer end of the gap (g) of the upper coil B Distance between the end of the third magnet (b) and the inner end of the gap (g) of the upper coil g Coil Gap length d of the core in the middle of the movable member d ₁ Distance between the end of the core and the coil d ₂ Distance between the two coils d ₃ Distance between the end of the coil and the outer end of the core d ₄ Wall of the movable member The optimum performance of the linear actuator can be obtained when the total stroke in each direction is S, which is equal to the dimensions A and B in FIG. That is, it is at the time of the following relationship.

A = B = S
g and d _{1 to} d ₄ are determined by the use conditions of the linear actuator. These values are selected to prevent magnetic saturation under the required thrust conditions. The dimension determination for preventing magnetic saturation of the core 2 is well understood by those skilled in the art.

  The important point of the above relationship can be understood with reference to FIG. FIG. 5 (c) shows a set of coils and a Halbach arrangement according to the present invention. The three images correspond to the three positions of the movable member. That is, the maximum position with respect to the first direction, the maximum position with respect to the second direction, and the midpoint position.

  The slight magnetic flux changes at the three positions in the hullback array and the movable member can be clearly read in FIG. 5 (c). In addition, a generally uniform transmission state of magnetic flux between the two coils and the movable member is shown over the entire stroke. As described above, the uniform coupling of magnetic flux results in uniform thrust generation over the entire stroke. Therefore, it can be understood from FIG. 5C that thrust can be generated over the entire stroke of the movable portion by the configuration according to the present invention. This is achieved by smoothly coupling the magnetic flux lines of the Hullback arrangement shown in FIG. 3 to the magnetic flux lines of the coil.

  Furthermore, in order to improve the linearity of the linear actuator and to prevent a step change in the coupling between the magnetic flux of the magnet and the coil, the end of the third magnet in the hullback arrangement that touches the other magnet is connected to the core gap. The movement is regulated so as not to overlap. As shown in FIG. 5 (c), the magnetic flux above the core gap is low. Similarly, referring to FIG. 3, the magnetic flux at reference points A and B is low. By ensuring that these points do not overlap (gaps), the linearity of the thrust stroke is optimized.

  The thrust of the linear actuator can be increased by configuring the relationship between the hullback and the coil as two coils and one hullback in series. However, in order to obtain the optimum thrust-stroke relationship, the above principle, ie, the end of the magnet in the middle of each hullback arrangement must be prevented from aligning with the core that is aligned with the core gap or coil. Don't be. Large thrust is obtained by a series configuration of these combinations, ie, a combination of appropriately arranged series-paired coil pairs and a series arrangement of three magnets along the armature.

  FIG. 6 shows an embodiment of the present invention with characteristic data and example dimensions.

  FIG. 6A shows the current directions of the coils 3 a and 3 b located in the core 2. In order for the shaft 5 to move to the upper part of the figure, the current polarity of the coil 3a flows toward the paper surface, and the current of the coil 3b flows in the direction coming out of the paper surface. On the contrary, when it is desired to move the shaft 5 downward, a current reverse to the above is applied.

  The magnets 6a and 6b magnetized in the radial direction and the magnet 8 magnetized in the axial direction constitute a hullback array. Referring to FIG. 3, in the current direction shown in FIG. 6 (a), shaft 5 is combined with the magnetic flux of the hullback arrangement to obtain a thrust toward the upper surface of the figure. On the other hand, when the current is reversed, a thrust toward the lower surface of the figure is obtained by coupling with the magnetic flux in the Halbach array.

  FIG. 6 (a) also shows that there is a gap 11 (or clearance) between the magnets 6a, 6b, 8 and the sleeve 4 (or tube), allowing the magnets 6a, 6b, 8 to move freely along the axis 7. Explaining things.

  FIG. 6A further shows the arrangement of the coils 3a and 3b in the core. As shown in the drawing, the cores 2 are arranged with discontinuous portions or gaps 12a (first gap) and 12b (second gap) on the side close to the Halbach array. In practice, the core has an “E” shape. As already described, the gaps 12a and 12b are provided to prevent a magnetic short circuit of the core 2.

  FIG. 6B shows the thrust / stroke characteristics of the linear actuator 1 shown in FIG. As a characteristic advantage, the thrust line substantially does not fluctuate at a stroke of −2.5 mm to +2.5 mm, that is, a total stroke of 5 mm. In fact, the variation is only 10N in the entire stroke.

  FIG. 6C shows the interlinkage magnetic flux of two coils at a stroke of 5 mm. “Upper coil” corresponds to the coil 3b, and “Lower Coil” corresponds to the coil 3a.

  FIG. 7 shows magnetic flux lines at the current polarity shown.

  FIG. 7A shows the linear actuator at the midpoint position. The midpoint position is a zero stroke position where the radially magnetized magnets (6a, 6b) and the axially magnetized magnet (8) are located between the two coils. No current is supplied and the movable member is stationary. The magnetic flux lines pass through the hullback array magnet and the core.

  The first and second currents are applied to the two coils by the means control unit described below and excited. The coils are connected in series or suitably connected in parallel.

  In FIG. 7B, a current in a direction entering the paper surface is applied to the upper coil, and a current coming from the paper surface is applied to the lower coil. As a result, the hullback array magnet, and thus the shaft 5, is moved from the midpoint position to the position shown in FIG. This is a result of the magnetic coupling (with the coil) from the array shown in FIG.

Further, as shown in FIG. 7B, the end A ₁ of the intermediate magnet 8 in the Hullback arrangement is aligned with the end C ₁ of the gap of the core 2. The hullback array is arranged so as not to advance any further. As shown in the figure, the magnetic coupling between the coil and the magnetic flux in the Halbach array is kept uniform. Movable member is move beyond the limits defined in C ₁ point, linearity of thrust compromise forced.

FIG. 7C shows a situation where a reverse current is applied. In FIG. 7C, a current in the direction coming out from the figure flows through the upper coil, and a current in the direction going into the figure flows through the lower coil. Therefore, the Halbach array works to move downward in the figure. End A ₂ of the intermediate magnets are to be aligned with the end C ₁ of the gap of the core. Again, the hullback array is kept from moving any further, and similarly, the magnetic coupling is uniform as shown.

  As can be understood from FIGS. 7B and 7C, by restricting the movement of the Hullback array magnet so that the end of the intermediate magnet does not overlap the gap end of the core, ) Linearity is optimized. The stroke of the linear actuator can be increased by either increasing the coil interval or decreasing the magnet length (or combination).

  Those who are familiar with this area can recognize that the member or the shaft to which the hullback array magnet is attached is moved by controlling the current. With precise current control, precise movement can be controlled. Further, the movement of the mounting member can be quickly performed by changing the current quickly, and further, the weight can be further strengthened by reducing the weight of the mounting member or the shaft, that is, the inertia.

  As shown in FIGS. 7 (a)-(c), the optimization of the magnetic saturation of the core is dependent on the dimensions of the core as well as the length of the hullback array magnet for a given current value and thrust per unit stroke. The size of the gap in the core is determined.

  FIG. 8 shows a configuration example of the control device of the linear actuator mentioned here. The two coils of the linear actuator 1 are connected to the drive unit 13 via a suitable interface 14 and receive current. In the figure, the coils are connected in series, but may be connected independently. The drive unit 13 and interface 14 receive signals from a digital signal processor 15 or equivalent, which receive signals 16 from other units or users. In order to determine the position of the linear actuator, a position sensor 17 is attached as necessary, and is connected to the drive unit 13 and the interface 14 via the control line 18. The adoption of other control units can be recognized by those familiar with this area.

  9-12 are cross-sectional views of the linear actuator in which the taper angle θ of the adjacent portion 20 of the magnet 6a and the magnet 8 and the adjacent portion 19 of the magnet 6b and the magnet 8 is changed, and an explanatory view showing the magnetic field analysis result. 9 to 12 show only the taper angle θ changed, and the other parts are the same.

  FIG. 9A shows a cross-sectional shape when the taper angle θ of the adjacent portion 20 of the magnet 6a and the magnet 8 and the adjacent portion 19 of the magnet 6b and the magnet 8 is 90 °, and FIG. 9B shows the magnetic field analysis thereof. It is a result (magnetic flux flow vector and maximum thrust value).

  FIG. 10A shows a cross-sectional shape when the taper angle θ of the adjacent portion 20 of the magnet 6a and the magnet 8 and the adjacent portion 19 of the magnet 6b and the magnet 8 is 45 °, and FIG. 10B shows the magnetic field analysis thereof. It is a result (magnetic flux flow vector and maximum thrust value).

  FIG. 11A shows a cross-sectional shape when the taper angle θ of the adjacent portion 20 of the magnet 6a and the magnet 8 and the adjacent portion 19 of the magnet 6b and the magnet 8 is 30 °, and FIG. It is a result (magnetic flux flow vector and maximum thrust value).

  FIG. 12A shows a cross-sectional shape when the taper angle θ of the adjacent portion 20 of the magnet 6a and the magnet 8, and the adjacent portion 19 of the magnet 6b and the magnet 8 is 60 °, and FIG. It is a result (magnetic flux flow vector and maximum thrust value).

  When the taper angle θ is 45 ° (FIG. 10), the flow of the magnetic flux in the adjacent portions 19 and 20 becomes smooth, and is the maximum compared to the case where the conventional taper angle θ is 90 ° (FIG. 9). The thrust value is the largest at 63.67. By setting the taper shape of the adjacent portions 19 and 20 to a taper angle of around 45 °, it is possible to provide a linear actuator that is small in size, high in efficiency and low in heat generation. Further, since the amount of rare earth magnet can be reduced, the cost is reduced.

  FIG. 13 is an explanatory diagram showing a procedure for assembling the magnets 6 a, 6 b, and 8 to the shaft 5. When the magnets 6 a, 6 b, 8 divided in the circumferential direction are bonded onto the shaft 5, it takes time for the bonding work by repelling or attracting each other, but the magnet 8 in the axial direction is bonded to the shaft 5. Later, the assembly work is facilitated by performing the assembly so as to be slid from both sides while utilizing the tapered shape in the procedure of bonding the radial magnets 6a and 6b.

It is sectional drawing of the linear actuator of this invention. It is sectional drawing of a hullback magnet structure. It is a magnetic flux diagram of a hullback magnet. It is a 2nd sectional view of the linear actuator of the present invention. It is explanatory drawing which shows the optimal characteristic of the linear actuator 1 by this invention, a cross-sectional dimension, and a hullback arrangement | sequence. It is explanatory drawing which shows the Example of this invention with the characteristic data and the example of a dimension. The magnetic flux lines in the current polarity are shown. It is a figure which shows the structural example of the control apparatus of a linear actuator. It is explanatory drawing which shows the cross section of a linear actuator in case the taper angle (theta) of the adjacent part of a magnet is 90 degrees, and its magnetic field analysis result. It is explanatory drawing which shows the cross section of a linear actuator in case the taper angle (theta) of the adjacent part of a magnet is 45 degrees, and its magnetic field analysis result. It is explanatory drawing which shows the cross section of a linear actuator in case the taper angle (theta) of the adjacent part of a magnet is 30 degrees, and its magnetic field analysis result. It is explanatory drawing which shows the cross section of a linear actuator in case the taper angle (theta) of the adjacent part of a magnet is 60 degrees, and its magnetic field analysis result. It is explanatory drawing which shows the assembly | attachment procedure of a magnet.

Explanation of symbols

1 Linear actuator 2 Core (coil member)
3a coil (coil member; first coil)
3b Coil (coil member; second coil)
4 Sleeve (non-magnetic member)
5 Shaft (movable member)
6a Magnet (movable member; first magnet)
6b Magnet (movable member; second magnet)
7 axis 8 magnet (movable member; 3rd magnet)
12a 1st gap 12b 2nd gap 19 Adjacent part 20 Adjacent part

Claims (15)

It has a coil member and a movable member that can reciprocate,
The movable member has a reciprocally movable shaft, and is disposed along the shaft so as to be separated from the first magnet and the second magnet, and the first magnet and the second magnet. And a third magnet magnetized in a different direction from the first and second magnets,
The coil members have a first coil and a second coil which is arranged and coaxially apart along said axis,
The coil member further includes a core that houses the first and second coils,
The core is formed with a first gap and a second gap that respectively extend between the first coil, the second coil, and an end of the core adjacent to the movable member,
The movable member is arranged to move between a maximum position in a first direction and a maximum position in a second direction, and the first position of the third magnet is at the maximum position in the first direction. When the end on the direction side is at the maximum position in the second direction, the end on the second direction side of the third magnet is between the first gap and the second gap. Align with the core part,
A linear actuator characterized by that.   The movable member includes a shaft, the first magnet magnetized in a radial direction of the shaft, and the second magnet magnetized in a direction opposite to the first magnet. The linear actuator according to claim 1.   The said 1st magnet, the said 2nd magnet, and the said 3rd magnet are mutually arrange | positioned in series mutually in parallel with the axis | shaft of the said movable member, The any one of Claim 1 or 2 characterized by the above-mentioned. A linear actuator according to any of the above.   4. The linear actuator according to claim 1, wherein the first magnet, the second magnet, and the third magnet extend in a circumferential direction of the movable member. 5. .   The linear actuator according to claim 2, wherein the shaft is made of a magnetic material.   The said shaft is comprised with a nonmagnetic material, The said 1st magnet, the said 2nd magnet, and the said 3rd magnet are installed in the circumferential direction of the said shaft, The Claim 2 characterized by the above-mentioned. Linear actuator. The movable member is arranged to move between a maximum position in the first direction and a maximum position in the second direction, and is intermediate between the maximum position in the first direction and the maximum position in the second direction. In the initial position, the first magnet is disposed to face the first coil, and the second magnet is disposed to face the second coil. Item 7. The linear actuator according to at least one of Items 1 to 6 . The coil member extends around said movable member, said movable member is the movable along the coil member of the shaft, the linear actuator according to at least any one of claims 1 to 7, characterized in that. The first coil and the second coil are configured to receive an electric current, and in order to move the movable member in a first direction, the electric current flows in a first polarity, and the first direction is when moving in a second direction opposite, wherein the first polarity current flow to the second polarity opposite linear actuator according to at least any one of claims 1 to 8, characterized in that . Nonmagnetic members, said interposed between the coil members and the movable members, the linear actuator according to at least any one of claims 1 to 9, characterized in that. The linear actuator according to claim 10 , wherein the non-magnetic member has a sleeve extending in a longitudinal direction of movement of the movable member. Gap, the linear actuator according to claim 10 or claim 11 wherein said movable member is provided between the non-magnetic member, characterized in that. An armature, and a first coil and a second coil surrounding the armature, the armature being arranged along the armature and spaced apart from each other in the radial direction of the armature. A first magnet and a second magnet magnetized; a third magnet disposed between the first magnet and the second magnet; and the first coil and the second magnet. The coil is housed in a core, and the core includes a first gap and a second gap extending between the first coil, the second coil, and an end of the core proximate to the armature, respectively. It has a gap,
The armature is set to move between a maximum position in a first direction and a maximum position in a second direction opposite to the first direction, and at the maximum position in the first direction, the armature The end of the third magnet on the first direction side is at the maximum position in the second direction, and the end of the third magnet on the second direction side is the first gap and the end of the third magnet. A linear actuator, wherein the linear actuator is aligned between the second gaps .   The at least 1 adjacent part of the said 1st magnet, the said 3rd magnet, the said 2nd magnet, and the said 3rd magnet exhibits a taper shape, Either of Claim 1 or 2 characterized by the above-mentioned. Linear actuator.   The linear actuator according to claim 1, wherein the number of magnets of the movable member is three, and the number of coils of the coil member is two.

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