Linear motor and method for its manufacture

Abstract

Linear motor for obtaining a longitudinal force for rectilinear movement using a magnetic field and a current-carrying winding, wherein: a rod (1) having magnets (3); a plurality of windings (4) surrounding the rod (1) and arranged in an axial direction of the rod (1); a housing (2) covering the windings (4); and a winding holder (5, 13) which holds the windings (4) in the housing (2), the winding holder (5, 13) having a holder main body (5a, 11a, 12a) extending in a winding arrangement direction and a plurality of spacer portions (5b, 11b, 12b), which are made of resin and are arranged between two of the windings (4), wherein the spacer portions (5b, 11b, 12b) are formed integrally with the holder main body (5a, 11a, 12a), wherein the housing (2) is formed by insert molding, wherein the winding holder (5, 13) and the windings (4) fitted into the winding holder (5, 13) are inserted into a mold.

Description

TECHNICAL FIELD

[0001] The present invention relates to a linear motor equipped with magnets and windings for obtaining a longitudinal force for linear movement based on a magnetic field from the magnet and current flowing through the winding. More specifically, the present invention relates to a rod-type linear motor in which a rod with magnets is inserted into a plurality of stacked windings. TECHNICAL BACKGROUND

[0002] A linear motor consists of a stator and a rotor, which are essentially constructed in the same way as a rotary motor, but are linearly elongated. In the linear motor, electrical energy is converted into linear force for linear motion. With this linear force, the linear motor is used as a single-axis actuator to move a movable object in a straight line.

[0003] From the perspective of shapes, linear motors can be divided into a rod type and a flat type. The rod-type linear motor is provided with multiple cylindrical windings arranged one above the other, and a rod with magnets is inserted into a hole (cavity) formed by the stacked windings. The multiple windings are formed, for example, as three phases consisting of U, V, and W phases. When three-phase currents whose phases are 120 degrees different from each other are supplied to the windings, magnetic fields are generated to move along the direction of the axis line of the windings.

[0004] These moving magnetic fields exert a longitudinal force on the rod, causing the rod to move linearly relative to the windings at the speed of the moving magnetic fields. In contrast, the flat-type linear motor is equipped with several plate-shaped magnets arranged on a rail track and several windings arranged facing the rail track. Regarding the linear motion of the windings relative to the magnets, this flat-type linear motor follows the same principles as the rod-type linear motor.

[0005] The winding assembly of a rod-type linear motor is performed as follows. First, the windings and the spacers to be arranged between the windings are alternately fitted onto a winding assembly shaft as a jig. Each spacer is ring-shaped and serves to insulate adjacent windings from each other. After all the windings and spacers are installed, the windings are wired, with their phases divided into U, V, and W by soldering the third winding lead wires. Each of the soldered lead wires is surrounded by an insulating tube.

[0006] In the conventional winding assembly method of a linear motor, the alternating fitting of windings and spacers onto the winding assembly shaft is followed by winding connection operations equal to the number of windings. This results in increased time and labor consumption as the number of windings increases. When the windings and spacers are arranged sequentially, fluctuations occur not only in the winding pitch but also in the overall length of the winding unit due to the accumulation of dimensional differences between the respective windings.

[0007] Patent Document 1 describes a method of assembling a winding unit by inserting windings into a winding guide one at a time, or in a number of two at a time, and laminating a plurality of such winding guides with the windings inserted therein.

[0008] Patent Document 1: Japanese Patent Laid-Open Publication No. JP 2004–357464 A

[0009] Further prior art is known from the documents DE 102 44 261 A1, JP S60– 102 866 A and DE 11 51 308 A. DESCRIPTION OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] However, even if the method described in Patent Document 1 is used, fluctuations in the total length of the winding unit occur due to the stacking of winding guides. Furthermore, such a method requires wire connection operations equal to the number of windings, and such operations require considerable manpower.

[0011] Therefore, an advantage of the present invention is to provide a linear motor and a manufacturing method thereof which can simplify the assembly of a winding unit and can stabilize the overall length of the winding unit and the winding pitch. MEASURES TO RESOLVE THE PROBLEMS

[0012] To solve the problems described above, the invention is a linear motor with the features according to patent claim 1.

[0013] The invention according to claim 2 is characterized in that the linear motor according to claim 1 further comprises an insulating substrate having a through hole for the passage of each of the lead wires of the windings and a conductive pattern for wiring the windings.

[0014] The invention according to claim 3 is characterized in that in the linear motor of claim 2, the insulating substrate is a separate part from the holder main body and is mounted on the holder main body having a wiring hole for each of the lead wires of the windings.

[0015] The invention according to claim 4 is characterized in that in the linear motor according to claim 1, the holder main body comprises a pair of holder main bodies which are plate-shaped and are each provided on one of the sides of a center line of the windings so as to surround the windings, and each of the holder main bodies has divided spacer portions formed integrally therewith, wherein when the holder main bodies are assembled in pairs, the divided spacer portions form the spacer portions in a ring shape.

[0016] Furthermore, the invention includes a method for producing a linear motor according to claim 5.

[0017] The invention according to claim 6 is characterized in that the method of claim 5 further comprises the step of passing each lead wire of the windings through a through hole of an insulating substrate having a conductive pattern for wiring the windings and for soldering the lead wire. IMPACT OF THE INVENTION

[0018] In the invention according to claim 1, the winding unit can be assembled by fitting each winding between spacer portions of the winding holder, thereby enabling a reduction in assembling steps for the winding unit, and stabilizing the winding pitch and the overall length of the winding unit.

[0019] In the invention according to claim 2, the windings are wired by passing the lead wires of the windings positioned by the winding holder through wiring holes of the insulating substrate and soldering the lead wires. Therefore, the wiring of the windings is simplified.

[0020] In the invention according to claim 3, the winding holder is separated from the insulating substrate. Therefore, the winding holder and the insulating substrate can be easily manufactured.

[0021] In the invention according to claim 4, the coils are held in balance by the paired holder main bodies provided on the respective sides of the coil center line. Therefore, the coils can be stably held in the housing.

[0022] In the invention according to claim 5, the winding unit can be assembled by fitting each winding between spacer portions of the winding holder, thereby enabling a reduction in the assembling steps of the winding unit and stabilizing the winding pitch and the overall length of the winding unit.

[0023] In the invention according to claim 6, the windings are wired by passing the lead wires of the windings, which are positioned by the winding holder, through wiring holes of the insulating substrate, and soldering the lead wires. Therefore, the wiring of the windings is facilitated. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a linear motor according to an embodiment of the present invention (including a partial sectional view thereof); Fig. 2 is a cross-sectional view showing windings and magnets of the linear motor; Fig. 3 is a cross-sectional view showing a winding unit held in a winding holder; Fig. 4 is a plan view of an insulating substrate (showing a conductive pattern); Fig. 5(A) and Fig. 5(B) are views each explaining a winding holder (where Fig. 5(A) is a front view, and Fig. 5(B) is a cross-sectional view along the axis line); Fig. 6(A) to 6(D) are views each explaining another example of a winding holder ( Fig. 6(A) is a supervision, Fig. 6(B) is a side view, Fig. 6(C) is a bottom view, and Fig. 6(D) is a front view); and Fig. 7(A) and Fig. 7(B) are views each explaining another example of a winding holder ( Fig. 7(A) is a side view, and Fig. 7(B) is a front view). DESCRIPTION OF REFERENCE SYMBOLS 1 rod 2 housings 3 Magnet 4 windings 4a Conductor wire 5, 13 winding holder 5a Holder main body 5b Spacer section 6 Insulating substrate 6a Through hole 6b Conductive pattern 11a, 12a Holder main body 11b, 12b Split spacer section BEST MODE FOR CARRYING OUT THE INVENTION

[0024] An embodiment of the present invention will now be described with reference to the accompanying drawings. Fig. 1 shows a perspective view of a linear motor according to an embodiment of the present invention. The linear motor according to this embodiment is a single-axis actuator including a rod 1 that moves in the axial direction of the rod 1 with respect to a housing 2. Such a linear motor is used to move a movable body, such as electronic components, in the direction of one axis. Specifically, for example, such a linear motor is used in a head shaft of a chip mounter for mounting a chip-shaped electronic component in a predetermined position. This linear motor can be used not only as a single-axis actuator but also as a multi-axis actuator when multiple linear motors are operated together in parallel, thereby increasing the operating efficiency.

[0025] Like a rotary type motor, the linear motor obtains motive power by current passing through windings 4 and a magnetic field of magnets 3. On the other hand, since the linear motor is designed to move rectilinearly, unlike the rotary type motor, a plurality of windings 4 are linearly stacked, and the rod 1 with magnets 3 inserted therein passes through the stacked windings 4. When current passes through the windings 4, the rod 1 moves in its axial direction.

[0026] Next, a description is given regarding the principle of the linear motor. Fig. Figure 2 shows a positional relationship between magnets 3 and windings 4 of the linear motor. In a cavity of the rod 1, a plurality of disc-shaped magnets 3 (segment magnets) are stacked one above the other so that like magnetic poles face each other, that is, an N pole and an N pole face each other, and an S pole and an S pole face each other. A plurality of windings 4 are stacked around the rod 1 to cover the rod 1. Three of the windings 4 each form a three-phase winding group consisting of a U-phase winding, a V-phase winding, and a W-phase winding. A plurality of winding groups are assembled into a winding unit. When three-phase current having phases different from each other by 120 degrees is passed through the three-phase winding groups of the U, V, and W phases, a magnetic field occurs that moves in the axial direction of the rod 1.The magnets 3 in the rod 1 receive a longitudinal force from the magnetic field, so that they perform a rectilinear movement relative to the windings 4 synchronously with the speed of movement of the magnetic field.

[0027] Next, a description is given regarding a construction of the linear motor. As in Fig. As shown in Figure 1, the rod 1 of the linear motor is supported by a housing 2 so as to be movable in the axial direction of the rod 1. The winding unit is supported by a winding holder 5, and this winding unit and the winding holder 5 are covered by the housing 2.

[0028] The rod 1 is made of, for example, a non-magnetic material such as stainless steel and has a hollow space like a tube. As described above, the plurality of disc-shaped magnets 3 (segment magnets) are arranged one above the other in the hollow space of the rod 1 so that like magnetic poles face each other. Between every two of the magnets 3 is a pole piece (magnetic pole block 7) made of a magnetic material such as steel or the like.

[0029] Each coil 4 is formed by a spirally wound copper wire and is held by the coil holder 5. In the present embodiment, in order to downsize the housing 2, the housing 2 is formed by insert molding, that is, by inserting the coils 4 and the coil holder 5 into an injection molding die, and filling the die with molten resin or special ceramic. When the molding is completed and a molded product is removed from the die, the coils 4 are surrounded by the housing 2. This insert molding has the advantage of reducing the thickness of the housing 2. For example, when linear motors are aligned to be inserted, downsizing of each linear motor is required.Here, even if no insert molding is performed, the windings 4 held in the winding holder 5 may be held in the case 2 made of aluminum, and a space between the windings 4 and the case 2 may be filled with an adhesive to thereby fix the windings 4 and the winding holder 5 to the case 2.

[0030] Since the housing 2 is mounted on a component that uses the linear motor as a single-axis actuator, the housing 2 is made of a material with high mechanical rigidity. Furthermore, to maintain insulation between the housing 2 and the windings 4, the material of the housing 2 also has good insulation properties. Furthermore, a plurality of fins 2a are provided in the housing 2 to improve heat dissipation from the windings 4.

[0031] When the linear motor is in operation, the rod 1 is suspended in the windings 4. To support the linear movement of the rod 1, bushings 8 are provided, which are fixed in a respective end part 9, each provided at one of the two ends of the housing 2.

[0032] Fig. 3 illustrates a winding unit supported by the winding holder 5. The winding unit includes several, or, for example, seven dozen, windings 4, each of which is made of multiple spiral turns of copper wire. Each lead wire 4a of each winding 4 must be connected, but if the lead wires 4a are soldered individually, significantly more man-hours are required. To simplify the wiring of the lead wires 4a of the windings 4, an insulating substrate 6 is provided.

[0033] Fig. 4 is a plan view of the insulating substrate 6. The insulating substrate 6 has through holes 6a through which the lead wires 4a of the plurality of windings 4 are passed, and a conductive pattern 6b for wiring the plurality of windings 4. The conductive pattern 6b is formed to connect a U-phase winding to a U-phase winding, a V-phase winding to a V-phase winding, or a W-phase winding to a W-phase winding. The wiring of the windings 4 is performed by passing a lead wire 4a of a winding 4 through a corresponding through hole 6a and soldering the lead wire 4a to the through hole 6a. This process can be automated by providing reflow soldering.

[0034] Fig. 5(A) and Fig. 5(B) are views illustrating in detail windings 4 and a winding holder holding the windings 4. Since it is necessary to insulate adjacent windings 4 from each other, a spacer portion 5b made of resin is interposed as an insulating material between two adjacent windings 4. Each spacer portion 5b is formed in the shape of a circular ring, like the shape of the front surface of each winding 4. Conventionally, spacer portions and windings were individually stacked on top of each other in a winding unit, but this operation required more man-hours, and the overall length of the winding unit was unstable. To solve this problem, spacer portions 5b are formed integrally with a plate-shaped holder main body 5a that is elongated in the winding arrangement direction of the windings 4.In other words, the winding holder 5 is formed by resin injection molding, and the winding holder 5 is formed to include a plate-shaped holder main body 5a elongated in the winding arrangement direction of the windings 4 and a plurality of thin spacer portions 5b rising from the holder main body 5a, wherein the holder main body 5a and the spacer portions 5b are integrally formed.

[0035] The length in the winding arrangement direction of the windings 4 in the holder main body 5a is approximately equal to the total length of the winding unit, and its width in the horizontal direction is approximately equal to the diameter of each winding 4. On the upper surface of the holder main body 5a, a mounting seat for the insulating substrate 6 is provided, which extends over the winding unit. On the side surfaces of the holder main body 5a, projections 5c (see Fig. 3) is provided to fix the winding holder to a mold during injection molding. The projections are provided to prevent displacement of the winding holder 5 due to pressure during injection molding. A recess 5d with a curved surface is provided under the lower surface of the holder main body 5a, corresponding to the outer shape of the windings 4. As shown in Fig. As shown in Figure 3, each winding 4 includes lead wires 4a. To guide the lead wires 4a into through holes 6a of the insulating substrate 6, the holder main body 5a has a plurality of wiring holes at the same positions as those of the through holes 6a of the insulating substrate 6.

[0036] As in Fig. As shown in Figure 5(A), each spacer portion 5b is formed to have an annular section, like the shape of the front surface of each coil 4, and is directed downward from the plate-shaped holder main body 5a. The spacer portion 5b is provided between every two adjacent coils 4 and also at each end of the coil unit. Therefore, the number of spacer portions 5b is one more than the number of coils.

[0037] The following describes a method of assembling windings using the winding holder described above. First, as shown in Fig. 3, windings 4 are fitted into the winding holder 5. When the winding holder 5, which has integrally formed spacer portions 5b and the holder main body 5a, is inserted, the windings 4 can be positioned in their arrangement direction only by fitting the windings 4 into the winding holder 5. At this stage, lead wires 4a of the windings 4 pass through wiring holes of the winding holder 5.

[0038] Then, the windings 4 are positioned with respect to the direction orthogonal to the winding arrangement direction by passing a winding arrangement shaft as a jig through the winding unit. This is followed by mounting an insulating substrate 6 on the winding holder 5, and passing the lead wires 4a of the windings 4 through the through holes 6a of the insulating substrate 6. Here, the step of passing the winding arrangement shaft through the winding unit may be performed after the step of mounting the insulating substrate 6 on the winding holder 5. Then, after the windings 4 are fixed to the winding holder 5 by an adhesive or the like, the lead wires 4a of the windings 4 are soldered to the through holes 6a of the insulating substrate 6.The winding holder 5, the plurality of windings 4, and the insulating substrate 6 are formed into a winding assembly, in which insert molding is then carried out to form the housing 2 as described above.

[0039] The Fig. 6(A) to 7(B) illustrate another example of the winding holder. Fig. 6(A) to 6(D) show a winding holder 13 which holds windings 4, while Fig. 7(A) and Fig. 7(B) shows an exploded view of the winding holder 13. The above-described winding holder 5 is provided on one side of the windings 4 with the holder main body 5a extending in the winding arrangement direction of the windings 4, while the winding holder 13 in this example has holder main bodies 11a and 12a arranged on both sides of the center line of the windings 4 so as to sandwich the windings 4.

[0040] When insert molding is performed on the winding assembly, the pressure of the molten resin acts on the winding assembly, and a force due to resin contraction also occurs. If the holder main body 5a is provided only on one side of the windings 4, the opposite side of the windings 4 is not held firmly, and some expansion or distortion may occur in the holder main body 5a. To solve this problem, the holder main bodies 11a and 12a of the winding holder 13 are balanced on the sides of the windings 4. In other words, the winding holder 13 consists of the holder main bodies 11a and 12a provided in pairs on the sides of the windings 4, and split spacer portions 11b and 12b integrally provided on the paired holder main bodies 11a and 12a.Then, each of the split spacer portions 11b and 12b has the shape of a half ring, and the upper split spacer portion 11b and the lower split spacer portion 12a are united into the annular spacer portion.

[0041] Similar to the holder described above, the holder main bodies 11a and 12a have projections for their attachment to the shape and recesses corresponding to the outer shape of each winding 4, and the insulating substrate 6 is mounted on the upper holder main body.

[0042] Also, in the coil holder 13 according to this example, the coil assembly is assembled by first fitting the coils 4 between the split spacer portions 11b of the upper holder main body 11a, and then attaching the split spacer portions 12b of the lower holder main body 12a thereto so that the split spacer portions 11b abut against the respective split spacer portions 12b. With this assembly, the number of steps can be reduced, and the overall length of the coil assembly can be stabilized.

[0043] The present invention is not limited to the above-described embodiments and can be embodied in various forms without departing from the scope of the present invention. For example, the linear motor according to the present invention is not limited to a single-axis actuator and can be used in damping a suspension device for automobiles. In this case, a damping force can be generated actively by changing the position of the rod and using current passing through the windings, or passively by using the linear motor as an electric generator. Furthermore, the insulating substrate for wiring can serve as a holder main body. In this case, the spacer portion is integrally molded with the insulating substrate by injection molding.Furthermore, in the embodiments described above, the rod moves rectilinearly relative to the windings, but the windings can also move rectilinearly relative to the rod.

Claims

[1] Linear motor for obtaining a longitudinal force for rectilinear movement using a magnetic field and a current-carrying winding, wherein: a rod (1) having magnets (3); a plurality of windings (4) surrounding the rod (1) and arranged in an axial direction of the rod (1); a housing (2) covering the windings (4); and a winding holder (5, 13) which holds the windings (4) in the housing (2), the winding holder (5, 13) having a holder main body (5a, 11a, 12a) extending in a winding arrangement direction and a plurality of spacer portions (5b, 11b, 12b), which are made of resin and are arranged between two of the windings (4), wherein the spacer portions (5b, 11b, 12b) are formed integrally with the holder main body (5a, 11a, 12a), wherein the housing (2) is formed by insert molding, wherein the winding holder (5, 13) and the windings (4) fitted into the winding holder (5, 13) are inserted into a mold. [2] A linear motor according to claim 1, further comprising an insulating substrate (6) having a through-hole (6a) for each of lead wires (4a) of the windings (4) to pass therethrough, and a conductive pattern (6b) for wiring the windings (4). [3] A linear motor according to claim 2, wherein the insulating substrate (6) is a separate part from the holder main body (5a, 11a, 12a) and is mounted on the holder main body (5a, 11a, 12a) having a wiring hole for each of the lead wires (4a) of the windings (4). [4] Linear motor for obtaining a longitudinal force for rectilinear movement using a magnetic field and a current-carrying winding, wherein: a rod (1) having magnets (3); a plurality of windings (4) surrounding the rod (1) and arranged in an axial direction of the rod (1); a housing (2) covering the windings (4); and a winding holder (13) which holds the windings (4) in the housing (2), the winding holder (13) having a holder main body (11a, 12a) extending in a winding arrangement direction and a plurality of spacer portions (11b, 12b) made of resin and each arranged between two of the windings (4), the spacer portions (11b, 12b) being formed integrally with the holder main body (11a, 12a), wherein the holder main body (11a, 12a) comprises a pair of holder main bodies (11a, 12a) which are plate-shaped and each provided in one side of a center line of the windings (4) so as to surround the windings (4), and each of the holder main bodies (11a, 12a) has divided spacer portions (11b, 12b) integrally formed therewith, wherein, when the holder main bodies (11a, 12a) are assembled in pairs, the divided spacer portions (11b, 12b) form the spacer portions in a ring shape. [5] A method for manufacturing a linear motor comprising a rod (1) with magnets (3) and a plurality of windings (4) surrounding the rod (1) and arranged in an axial direction of the rod (1), and configured to obtain a longitudinal force for rectilinear movement by using a magnetic field of the magnets (3) and a current flowing through the windings (4), comprising the following steps: Holding all the windings (4) in a winding holder (5, 13) having a holder main body (5a, 11a, 12a) extending in the winding arrangement direction, and a plurality of spacer portions (5b, 11b, 12b) made of resin and each disposed between two adjacent coils (4), the spacer portions (5b, 11b, 12b) being integrally formed with the holder main body (5a, 11a, 12a); and Covering the windings (4) with a housing (2) by insert molding, wherein the winding holder (5, 13) and the windings (4) fitted into the winding holder (5, 13) are inserted into a mold. [6] A method according to claim 5, further comprising the step of passing each lead wire (4a) of the windings (4) through a through-hole (6a) of an insulating substrate (6) having a conductive pattern (6b) provided for wiring the windings (4), and soldering the lead wire (4a).

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