Linear Motor and Linear Head Modules

Abstract

To provide a linear motor which makes an excessive force less likely to be generated in a bearing supporting an output shaft part.SOLUTION: A linear motor 10 has: a movable element 60 having an output shaft part 61; a detection part 42 capable of detecting a position as seen in a thrust axis direction of the output shaft part 61; and a detected part 43 fixed to the movable element 60. The movable element 60 has: an attachment pedestal 70 attached with the detected part 43; and a metallic fastening member 63 which fastens the attachment pedestal 70 to one end surface 61c as seen in the thrust axis direction of the output shaft part 61b. The attachment pedestal 70 has: a metallic fastened part 71; and a resin attachment part 72 having an attachment surface 73 of the detection part 42 provided at a position offset from a thrust axis.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a linear motor and a linear head module. [Background technology]

[0002] A linear head module disclosed in Patent Document 1 is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2014-192959 Summary of the Invention [Problem to be solved by the invention]

[0004] The linear head module described in Patent Document 1 has multiple linear motors. In the mover of this linear motor, a block member is connected to an output shaft portion extending along a thrust axis, and an extension member is screwed to the block member.

[0005] In the linear head module of Patent Document 1, the extension member is fixed to the block member by a screw that extends in a direction twisted relative to the thrust axis direction at a position away from the output shaft. When the mover suddenly accelerates or stops, a large force of inertia acts on the extension member in the thrust axis direction. Since the screw can absorb this force of inertia at the shaft, the device of Patent Document 1 has a rational design.

[0006] However, in recent years, there has been an increasing demand for higher speeds of the mover. In a linear head module that is required to operate at high speed, when the mover is subjected to sudden acceleration or deceleration, a large force of inertia also acts on the metal screw in the device described in Patent Document 1. When a large force of inertia acts on the screw, a large force acts on the output shaft in a direction intersecting the thrust axis direction, and there is a risk of an excessive load being generated on the bearing that supports the output shaft.

[0007] Therefore, the present invention provides a linear motor in which excessive force is unlikely to be generated in the bearings that support the output shaft portion, and a linear head module equipped with the linear motor. [Means for solving the problem]

[0008] A linear motor according to one aspect of the present invention comprises: a mover having an output shaft portion extending in a thrust axis direction; a detection unit capable of detecting a position of the output shaft portion in a thrust axial direction; A detection target portion fixed to the movable element, The mover further comprises: a mounting base on which the detection target portion is mounted; a metal fastening member that fastens the mounting base to one end surface of the output shaft portion in the thrust axial direction, The mounting base is a metal fastened portion sandwiched between one end face of the output shaft portion in the thrust axial direction and the fastening member; The detection portion has a mounting surface, which is made of resin and is disposed at a position offset from the thrust axis.

[0009] A linear head module according to one aspect of the present invention includes: A linear head module having a plurality of the linear motors, a housing that supports the mover movably in the thrust axis direction, the housing has a counter-output-side support wall that is provided on one side of the thrust axis and extends in a direction intersecting the thrust axis to support the mover movably in the thrust axial direction, The anti-output side support wall is provided with a through hole through which at least a part of the attachment portion can be inserted.

[0010] According to the present invention, a linear motor and a linear head module are provided in which excessive force is unlikely to be generated in the bearings that support the output shaft portion. [Brief description of the drawings]

[0011] [Figure 1] 1 is a perspective view of a linear head module according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a cross-sectional view of a linear head module. [Diagram 3] FIG. 4 is an enlarged view of a rear output shaft portion of the mover. [Figure 4] FIG. 2 is an enlarged perspective view showing the periphery of the mounting base. [Diagram 5] 13 is a view of the non-output side support wall as viewed from the output side of the thrust axis. FIG. [Figure 6] 13 is a cross-sectional view showing a support wall on the opposite side to the output side in which a through hole is provided. FIG. [Figure 7] 11 is a cross-sectional view of a linear head module according to a modified example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. For the sake of convenience, the description of the components having the same reference numbers as those already described in the description of the embodiment will be omitted. Also, for the sake of convenience, the dimensions of each component shown in the drawings may differ from the actual dimensions of each component.

[0013] Fig. 1 is a perspective view of a linear head module 1 including a linear motor 10 according to an embodiment of the present invention. In Fig. 1, the letter F indicates the front, the letter B indicates the rear, the letter U indicates the upper side, the letter D indicates the lower side, the letter R indicates the right side, and the letter L indicates the left side. In the following explanation, for convenience of explanation, the "left-right direction," "front-rear direction," and "up-down direction" will be referred to as appropriate. Here, the "up-down direction" is a direction that includes the "upward direction" and the "downward direction." The "front-rear direction" is a direction that includes the "forward direction" and the "rearward direction." The "left-right direction" is a direction that includes the "leftward direction" and the "rightward direction." In the following explanation, the direction of the thrust axis T of the linear head module 1 will be referred to as the "front-rear direction."

[0014] 1, the linear head module 1 has a plurality of linear motors 10 each having a mover 60 that moves in the front-rear direction (thrust direction), a housing 11, and a sensor unit 40 (see FIG. 2). In the illustrated example, the linear head module 1 has eight linear motors 10. Four linear motors 10 are arranged in the left-right direction on the upper stage, and four linear motors 10 are arranged in the left-right direction on the lower stage.

[0015] Fig. 2 is a cross-sectional view of the linear head module 1. Fig. 2 is a view of the linear head module 1 in a cross section extending in the front-rear and up-down directions. As shown in Fig. 2, each linear motor 10 has a stator 50 fixed to a housing 11, and a mover 60 that is movable in the front-rear direction relative to the stator 50.

[0016] The mover 60 has an output shaft portion 61 extending in the front-rear direction, and a magnet 62. The multiple magnets 62 are arranged in a row in the front-rear direction and connected to each other. The output shaft portion 61 is a rod-shaped member extending in the front-rear direction. The output shaft portion 61 has a front output shaft portion 61a provided in front of the magnet 62, and a rear output shaft portion 61b provided behind the magnet 62. A front portion of the front output shaft portion 61a is connected to an object to be driven by the linear head module 1.

[0017] The stator 50 has a back yoke 51 and a coil 52. In the example shown in the figure, the stator 50 further has a drive circuit board 53 that supplies power to the coil 52 to control the coil 52, and a cover 54 that houses the drive circuit board 53. The stator 50 is fixed to the housing 11.

[0018] The back yoke 51 is a member made of a magnetic material such as iron. In the illustrated example, the back yoke 51 is a cylindrical member extending along the output shaft portion 61. The output shaft portion 61 is accommodated inside the cylindrical back yoke 51 so as to be movable in the front-rear direction. In addition, a plurality of coils 52 are provided inside the cylindrical back yoke 51. The coils 52 are configured by winding electric wires in a cylindrical shape centered on an axis extending in the front-rear direction. The back yoke 51 converges the magnetic flux lines generated from the coils 52 to increase the magnetic force.

[0019] The driving circuit board 53 is connected to an electric wire extending from a power source (not shown). The driving circuit board 53 is housed in a plate-shaped cover 54 that is provided on the outer periphery of the cylindrical back yoke 51 and that houses the driving circuit board 53. An electric wire extends from the driving circuit board 53 to the coil 52 and supplies power to the coil 52. The driving circuit board 53 controls the direction and strength of the magnetic lines of force generated in the coil 52 by controlling the direction and amount of current supplied to the coil 52. This controls the direction and speed of movement of the output shaft 61.

[0020] 2, the stator 50 has a first bearing holder 20. The first bearing holder 20 is attached to the housing 11 and supports an output side end of the back yoke 51 of the stator 50. The first bearing holder 20 is provided at the output side end of the back yoke 51. The first bearing holder 20 has a first bearing 21 that supports the output shaft portion 61 movably in the front-rear direction.

[0021] The stator 50 has a second bearing holder 30. The second bearing holder 30 is attached to the housing 11 and supports the anti-output side end of the back yoke 51 of the stator 50. The second bearing holder 30 is provided at the anti-output side end of the back yoke 51. The second bearing holder 30 has a second bearing 31 that supports the output shaft portion 61 movably in the front-rear direction. In other words, the housing 11 supports the mover 60 via the first bearing 21 and the second bearing 31 so as to be movable in the direction of the thrust axis T.

[0022] The sensor unit 40 detects the position of the output shaft portion 61 in the direction of the thrust axis T. The sensor unit 40 includes a sensing circuit board 41 (circuit board), a detection portion 42, and a detected portion 43 fixed to the mover 60. The sensing circuit board 41 is fixed to the housing 11. The detection portion 42 is mounted on the sensing circuit board 41. Therefore, the detection portion 42 is immovable relative to the housing 11.

[0023] The sensor unit 40 in this embodiment is composed of an optical sensor. The detection section 42 includes a light emitting section and a light receiving section. Light emitted from the light emitting section is reflected by the detected section 43, and the reflected light is detected by the light receiving section. The detected section 43 has reflective sections having a predetermined width and non-reflective sections (or slits) having a lower reflectivity than the slit reflective sections, which are alternately arranged along the thrust axis T direction. When the output shaft section 61 moves in the thrust axis T direction, the detection section 42 detects or does not detect the reflected light, and the output of the detection section 42 changes. Based on this change in the output of the detection section 42, the position of the output shaft section 61 in the thrust axis T direction can be identified.

[0024] 3 is an enlarged view of the rear output shaft portion 61b of the mover 60. As shown in FIG. 3, the mover 60 has the rear output shaft portion 61b (output shaft portion), a mounting base 70 to which the detected portion 43 is attached, and a metal fastening member 63 that fastens the mounting base 70 to the rear output shaft portion 61b. In the illustrated example, the fastening member 63 is a bolt having a threaded portion and a head, which is screwed into the end face 61c of the rear output shaft portion 61b on the opposite side to the output side in the thrust axis T direction. The end face 61c of the rear output shaft portion 61b on the opposite side to the output side is provided with a screw hole having a thread groove formed on the inner peripheral surface. The fastening member 63 is screwed into this screw hole.

[0025] The mounting base 70 has a metal fastened portion 71 and a resin mounting portion 72. The fastened portion 71 is sandwiched between the anti-output side end face 61c of the rear output shaft portion 61b and the head of the fastening member 63. The fastened portion 71 is a cylindrical member having a through hole 71a penetrating in the direction of the thrust axis T through which the fastening member 63 is inserted. The diameter of the through hole 71a is larger than the diameter of the threaded portion of the fastening member 63 and smaller than the diameter of the head of the fastening member 63. The anti-output side end face 61c of the fastened portion 71 abuts against the head of the fastening member 63. The mounting portion 72 has a mounting surface 73 to which the detected portion 43 is attached. The mounting surface 73 is provided at a position offset from the thrust axis T. The mounting surface 73 extends parallel to the thrust axis T.

[0026] That is, the linear motor 10 according to this embodiment has the following features: A mover 60 having an output shaft portion 61 extending in the direction of a thrust axis T; A detection unit 42 capable of detecting the position of the output shaft portion 61 in the direction of the thrust axis T; A detection target portion 43 fixed to the movable element 60, The mover 60 further includes: a mounting base 70 on which the detection target portion 43 is mounted; a metal fastening member 63 for fastening the mounting base 70 to one end face 61 c of the output shaft portion 61 in the thrust axis T direction, The mounting base 70 is a metal fastened portion 71 sandwiched between one end face 61c of the output shaft portion 61 in the thrust axis T direction and the fastening member 63; The mounting portion 72 is made of resin and has a mounting surface 73 for the detected portion 43 provided at a position offset from the thrust axis T.

[0027] According to the linear motor 10 of this embodiment, the mounting portion 72, including the mounting surface 73 of the detected portion 43, which is provided at a position offset from the thrust axis T, is made of lightweight resin. Therefore, even if the mover 60 undergoes rapid acceleration or deceleration, the inertial force generated in the mover 60 can be kept small. Furthermore, because the metal fastening member 63 is fastened to the non-output side end face 61c of the rear output shaft portion 61b, no large moment of inertia is generated in the mover 60 at a position away from the thrust axis T, and excessive force is unlikely to act on the first bearing 21 and the second bearing 31 that support the output shaft portion 61. Unlike the present invention, the configuration of Patent Document 1 has a linear guide that movably supports a metal mounting base provided in the housing to receive this moment of inertia. With the linear motor 10 according to this embodiment, there is no need to provide such a linear guide. Furthermore, according to the linear motor 10 of this embodiment, the fastened portion 71 is made of metal, so the fastening member 63 can be tightly fastened to the fastened portion 71 compared to when the fastened portion 71 is made of resin. Therefore, the mounting base 70 is less likely to deform even if the output shaft portion 61 rapidly accelerates or decelerates, so that the detected portion 43 can be easily moved accurately along a trajectory parallel to the thrust axis T, and the detection accuracy of the detection portion 42 can be easily maintained. It is preferable to form the mounting base 70 by insert molding, in which the metal fastened portion 71 is placed in the cavity and then a resin material is poured in.

[0028] 3, the mounting portion 72 has a connecting portion 74 and a base portion 75 provided with a mounting surface 73. The connecting portion 74 is connected to the fastened portion 71 and extends in a direction intersecting the thrust axis T. The base portion 75 extends from the connecting portion 74 to the output side. According to the linear motor 10 of this embodiment, the base portion 75 is provided at a position folded back from the anti-output side end face 61c of the rear output shaft portion 61b to the output side, so that the dimension of the linear motor 10 in the direction of the thrust axis T can be made small.

[0029] Moreover, the linear head module 1 of this embodiment has a plurality of the above-mentioned linear motors 10. This linear head module 1 has a housing 11 that supports the mover 60 movably in the direction of the thrust axis T. Fig. 4 is an enlarged perspective view showing the periphery of the mounting base 70. As shown in Fig. 4, the housing 11 is provided on the counter-output side of the thrust axis T, and has a counter-output-side support wall 14 that extends in a direction intersecting the thrust axis T and supports the mover 60 movably in the direction of the thrust axis T. The counter-output-side support wall 14 is provided with an insertion hole 12 through which a base portion 75, which is at least a part of the mounting portion 72, can be inserted. Unlike the illustrated example, if no insertion hole is provided, there is a risk that the base portion will interfere with the non-output side support wall when the mover is positioned at the output side limit of its movable range. This would require the mover's movable range to be reduced, or the linear head module would have to be enlarged in the direction of the thrust axis T. In contrast, according to the linear head module 1 of this embodiment, when the mover 60 is positioned at the output side limit of its movable range, the base portion 75 can be positioned in the space on the output side of the non-output side support wall 14. This allows the mover 60 to be increased in movable range, or the linear head module 1 to be reduced in size in the direction of the thrust axis T.

[0030] Fig. 5 is a view of the non-output side support wall 14 as viewed from the output side of the thrust axis T. In the example shown in Fig. 5, a plurality of linear motors 10 are arranged in a first arrangement direction A1 intersecting the direction of the thrust axis T. That is, in the illustrated example, four linear motors 10 are arranged in the left-right direction. The insertion hole 12 is provided between the rear output shaft portions 11b adjacent to each other in the first arrangement direction A1 as viewed from the direction of the thrust axis T. According to the linear head module 1 of this embodiment, the space between the multiple linear motors 10 can be efficiently used to provide a space for accommodating the pedestal portion 75.

[0031] 5, the linear motors 10 arranged in the first arrangement direction A1 are also arranged in a second arrangement direction A2 intersecting the first arrangement direction A1. That is, four linear motors 10 arranged in the left-right direction are provided in two stages in the up-down direction, for a total of eight linear motors 10. The insertion hole 12 is provided between four rear output shaft portions 61b that are adjacent to each other and form a rectangular shape when viewed from the thrust axis T direction. According to the linear head module 1 of this embodiment, the space between the multiple linear motors 10 can be used more efficiently to provide a space for accommodating the pedestal portion 75.

[0032] Fig. 6 is a cross-sectional view showing the counter-output side support wall 14 provided with the insertion hole 12. As shown in Fig. 6, a partition cover 13 is provided on the output side of the counter-output side support wall 14. The partition cover 13 separates an accommodation chamber that accommodates at least a part of the mounting portion 72 exposed from the insertion hole 12 from a space on the output side of the counter-output side support wall 14. As shown in FIG. 2, the first bearing 21 and the second bearing 31 are located in the space on the output side of the anti-output side support wall 14. Lubricating oil is used in the first bearing 21 and the second bearing 31. If this oil evaporates and adheres to the electronic components, it will have an adverse effect on the electronic components. Alternatively, if the oil adheres to the detected portion 43, the sensitivity of the sensor unit 40 may decrease. Due to the provision of the insertion hole 12, there is a risk that oil generated in the space on the output side of the anti-output side support wall 14 will adhere to the detected portion 43 and the sensing circuit board 41. In the linear head module 1 according to this embodiment, the partition cover 13 makes it difficult for oil to adhere to the detection target portion 43 and the sensing circuit board 41. For convenience of illustration, the partition cover 13 is not shown in FIG.

[0033] In the linear head module 1 according to this embodiment, a plurality of detected parts 43 are provided on each mover 60, and a plurality of detecting parts 42 are provided on a single sensing circuit board 41. This makes it possible to reduce the number of parts.

[0034] Although the embodiment of the present invention has been described above, it goes without saying that the technical scope of the present invention should not be interpreted as being limited by the description of the embodiment. The embodiment is merely an example, and it is understood by those skilled in the art that various modifications of the embodiment are possible within the scope of the invention described in the claims. The technical scope of the present invention should be determined based on the scope of the invention described in the claims and its equivalents.

[0035] For example, in the above-described embodiment, the base portion 75 is folded back from the anti-output side end face 61c of the rear output shaft portion 61b toward the output side. However, as in the example shown in FIG. 7, the base portion 175 may be configured to extend from the anti-output side end face 61c of the rear output shaft portion 61b toward the anti-output side.

[0036] In the above embodiment, the magnetic material is cylindrical, but the shape of the magnetic material is not limited to this. For example, the magnetic material may be in the shape of a square tube or a plate. [Explanation of symbols]

[0037] 1 Linear Head Module 10. Linear motor 11. Housing 12 Insertion hole 13 Partition cover 14 Counter-output side support wall 20 First bearing holder 21 First bearing 30 Second bearing holder 31 Second bearing 40 Sensor unit 42 Detection unit 43 Detected part 50 stator 51 Back Yoke 52 Coil 53 Drive circuit board 60 Mover 61 Output shaft 61a Front output shaft 61b Rear output shaft 63 Fastening members 70 Mounting base 71 Part to be fastened 72 Mounting part 73 Mounting surface

Claims

1. a mover having an output shaft portion extending in a thrust axial direction; a detection unit capable of detecting a position of the output shaft portion in a thrust axial direction; A detection target portion fixed to the movable element, The mover further comprises: a mounting base on which the detection target portion is mounted; a metal fastening member that fastens the mounting base to one end surface of the output shaft portion in the thrust axial direction, The mounting base is a metal fastened portion sandwiched between one end face of the output shaft portion in the thrust axial direction and the fastening member; a mounting portion made of resin and having a mounting surface for the detected portion provided at a position offset from the thrust axis.

2. the mounting portion has a connecting portion connected to the fastened portion and extending in a direction intersecting the thrust axis, 2. The linear motor according to claim 1, wherein the mounting surface is provided on a base portion extending from the connecting portion to the other side of the thrust axis.

3. 2. The linear motor according to claim 1, wherein the mounting base is formed by insert molding.

4. 2. A linear head module having a plurality of the linear motors according to claim 1, a housing that supports the mover movably in the thrust axis direction, the housing has a counter-output-side support wall that is provided on one side of the thrust axis and extends in a direction intersecting the thrust axis to support the mover movably in the thrust axial direction, The linear head module, wherein the anti-output side support wall is provided with a through hole through which at least a part of the mounting portion can be inserted.

5. A plurality of the linear motors are arranged in a first arrangement direction intersecting the thrust axis direction, The linear head module according to claim 4 , wherein the through hole is provided between the output shaft portions adjacent to each other in the first arrangement direction when viewed from the thrust axis direction.

6. The linear motors arranged in the first arrangement direction are also arranged in a second arrangement direction intersecting the first arrangement direction, 6. The linear head module according to claim 5, wherein the through hole is provided between four of the output shaft portions adjacent to each other and forming a rectangular shape when viewed from the thrust axis direction.

7. A linear head module as described in claim 4, wherein a partition cover is provided on the other side of the thrust axis of the anti-output side support wall, separating a storage chamber that accommodates at least a portion of the mounting portion exposed from the through hole from a space on the other side of the thrust axis direction of the anti-output side support wall.

8. A plurality of the detection targets are provided on each of the movable elements, The linear head module according to claim 4 , wherein a plurality of the detection units are provided on a single circuit board.

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