JP2017153324A - Linear actuator unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear actuator unit capable of preventing superposition of electromagnetic noise on an output of a load sensor.SOLUTION: A linear actuator unit 1 includes: an electric linear actuator A; a load sensor L connected to the electric linear actuator A and detecting a load in an axial direction of the electric linear actuator A; and an insulating member I for electromagnetically insulating the load sensor L from the electric linear actuator A.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a linear actuator unit.

  The electric linear actuator is used in, for example, a load tester. In the load testing machine, the electric linear actuator is connected to the other end of the test piece having one end fixed, and a tensile load can be applied to the test piece by driving.

  Specifically, for example, in a conventional load tester, a support is provided on a table through which the output shaft of the electric linear actuator passes, and an upper grip for gripping the upper end of the test piece is attached to the upper end of the support. It has been. Further, a lower gripping tool is provided at the tip of the electric linear actuator provided under the table. And, with the lower end of the test piece connected to the electric linear actuator and the upper end of the test piece connected to the cross head, the electric linear actuator is driven to apply a tensile load to the test piece (for example, Patent Document 1).

  Such a load tester is generally provided with a load sensor such as a load cell in order to detect how much load is applied to the test piece by driving the electric linear actuator. More specifically, the load sensor is provided between the cross head and the gripper and detects a load input from the electric linear actuator.

JP 2009-014542 A

  In the vibration testing machine disclosed in Patent Document 1, when vibration is applied to a test piece at a high frequency with an electric linear actuator, electromagnetic noise generated from the electric linear actuator is superimposed on the output of the load sensor, and the correct load is obtained. There is a problem that detection becomes difficult.

  Accordingly, the present invention has been developed to improve the above-described problems, and an object of the present invention is to provide a linear actuator unit that can prevent electromagnetic noise from being superimposed on the output of the load sensor.

  In order to achieve the above object, a linear actuator unit according to claim 1 includes an electric linear actuator, a load sensor connected to the electric linear actuator for detecting an axial load of the electric linear actuator, and a load sensor from the electric linear actuator. And an insulating member that electromagnetically insulates. When the linear actuator unit is configured in this manner, the load sensor is electromagnetically insulated from the electric linear actuator by the insulating member, so that electromagnetic noise generated by energization of the electric linear actuator is not superimposed on the signal output from the load sensor. .

  The linear actuator unit according to claim 2 includes a connecting member for connecting the electric linear actuator to an external member via a load sensor, and the insulating member electromagnetically insulates the load sensor from the connecting member. ing. Therefore, the load sensor can be electromagnetically insulated not only from the electric linear actuator but also from the external member side connected to the connecting member, and a more accurate load can be detected.

  Furthermore, if the insulating member is made of synthetic resin as in the linear actuator unit of claim 3, the linear actuator unit can be reduced in weight while enabling electromagnetic insulation.

  Furthermore, in the linear actuator unit according to claim 4, the insulating member is connected to the tip of the electric linear actuator, and the first insulator for electromagnetically insulating the load sensor from the electric linear actuator is connected to the connecting member. And a second insulator that electromagnetically insulates the load sensor from the connecting member. When the linear actuator unit is configured in this way, the load sensor is electromagnetically insulated from both the electric linear actuator side and the connecting member side, so that a more accurate load can be detected.

  According to a fifth aspect of the present invention, the linear actuator unit includes an electric linear actuator and a load sensor that is connected to the electric linear actuator and detects an axial load of the electric linear actuator, and the load sensor is electromagnetically insulated. It has a configuration. When the linear actuator unit is configured in this manner, the load sensor itself is electromagnetically insulated from the electric linear actuator, and therefore, electromagnetic noise generated by energization of the electric linear actuator is not superimposed on a signal output from the load sensor.

  According to the linear actuator unit of the present invention, it is possible to prevent electromagnetic noise from being superimposed on the output of the load sensor.

It is a longitudinal cross-sectional view of the linear actuator unit in one embodiment of this invention. It is a longitudinal cross-sectional view of the linear actuator unit in the modification of one embodiment of this invention.

  Hereinafter, the linear actuator unit 1 in the embodiment of the present invention will be described based on an example in which the linear actuator unit 1 is applied to a vibration testing machine K. As shown in FIG. 1, a linear actuator unit U according to an embodiment includes an electric linear actuator A, a load sensor L that is connected to the electric linear actuator A and detects an axial load of the electric linear actuator A, and an electric motor An insulating member I that electromagnetically insulates the load sensor L from the linear actuator A and a connecting member 30 are provided.

  Hereinafter, each part of the linear actuator unit 1 will be described in detail. First, the electric linear actuator A includes a cylindrical base 2, a guide tube 3 connected to the right end of the base 2 in FIG. 1, and a cylindrical core 4 attached to the inner periphery of the guide tube 3. A stator S having a plurality of coils 5 mounted in a plurality of slots 4 a provided on the inner periphery of the core 4, a bottomed cylindrical bottom guide 6 connected to the left end of the base 2 in FIG. An inner rod 8 serving as a mover that houses and holds a field composed of a plurality of permanent magnets 9 that are inserted so as to be relatively movable in the axial direction and are arranged side by side in the axial direction, and the left end of the inner rod 8 in FIG. 1, a slider 10 that is slidably contacted with the inner periphery of the bottom guide 6, a cylindrical outer rod 11 that is slidably mounted on the outer periphery of the guide tube 3 in the axial direction, and the right end of the inner rod 8 in FIG. 1. Au A cover 12 for coupling in Figure 1 the right end of Roddo 11 is configured by a mounting shaft 13 provided at the tip of the cover 12.

  In the case of this embodiment, the inner rod 8 has a cylindrical shape, and houses and holds a plurality of permanent magnets 9 arranged in the axial direction therein, and a field is formed by these permanent magnets 9. ing. The inner rod 8 is preferably formed of a non-magnetic material because the magnetic flux concentrates and affects the magnetic flux around the outer periphery of the permanent magnet 9 when formed of a ferromagnetic material. Further, the number of permanent magnets 9 installed on the inner rod 8 can be arbitrarily determined. In this case, the permanent magnet 9 is magnetized so that the N pole and the S pole appear in the axial direction, and the adjacent permanent magnets 9 are held side by side in the axial direction on the inner rod 8 with the same poles facing each other. However, the poles may be magnetized so that the poles are different between the inner circumference and the outer circumference, and in any case, as long as the S pole and the N pole appear alternately along the axial direction of the inner rod 8. Good. In this embodiment, disk-shaped yokes 7 are interposed between the permanent magnets 9, whereby a magnetic field can be efficiently generated on the outer periphery of the inner rod 8. Further, in this embodiment, the inner rod 8 has a cylindrical shape and is hollow inside, and has a structure in which the permanent magnet 9 is accommodated therein. As an alternative, the permanent magnet 9 may be mounted on the outer periphery.

  A cover 12 is attached to the right end of the inner rod 8. The cover 12 includes a small diameter portion 12a that holds the right end of the inner rod 8, a flange 12b provided at the left end of the small diameter portion 12a, and a large diameter portion 12c provided on the outer periphery of the flange 12b. The right end of the outer rod 11 is attached to the inner circumference of the large diameter portion 12 c, and the outer rod 11 and the inner rod 8 are connected via the cover 12. A mounting shaft 13 is provided at the right end of the cover 12 so as to protrude rightward, and an inner ring 17 is attached to the outer periphery of the mounting shaft 13 by press fitting.

  Subsequently, the core 4 has a cylindrical shape, and slots 4a formed by annular recesses for holding the coils 5 are arranged on the inner periphery in the same number as the number of the coils 5 arranged in the axial direction. Further, annular magnetic teeth 4b are provided on both sides in the axial direction of the slot 4a, and when the annular coil 5 is mounted in the slot 4a, the magnetic teeth 4b are disposed at both ends of the coil 5 in the axial direction.

  The coil 5 is held by the core 4 so as to surround the outer periphery of the inner rod 8, and is opposed to a field composed of a plurality of permanent magnets 9 provided on the inner rod 8. The magnet 9 is attracted, and the inner rod 8 can be driven with respect to the stator S in the axial direction which is the left-right direction in FIG.

  When the inner rod 8 is driven in the axial direction, the slider 10 connected to the left end of the inner rod 8 is guided to the bottom guide 6 and the outer rod 11 connected to the right end of the inner rod 8 is connected to the guide tube. 3 will guide you. Therefore, the inner rod 8 is smoothly driven in the axial direction without being shaken relative to the stator S, and can exhibit a stable thrust.

  In addition, trunnion pins 2 a and 2 b are provided on the outer periphery of the base 2. The trunnion pins 2a and 2b are inserted into holes 15a and 15b provided in the rectangular frame 15, and the electric linear actuator A can be rotated around the axis of the trunnion pins 2a and 2b while being inside the frame 15. Contained. A chuck fitting 16 capable of gripping the right end of the test piece T in FIG. 1 is provided on the inner peripheral side of the right side of the frame 15.

  The load sensor L detects the amount of elastic deformation of the first insulator 18 having cylindrical elasticity attached to the outer periphery of the inner ring 17 to detect the axial load of the electric linear actuator A. . In this example, the load sensor L includes an outer ring 19 mounted on the outer periphery of the first insulator 18 and a detection unit made of an unillustrated strain gauge that is attached to the right end of the first insulator 18 to form a bridge circuit. 20 and a voltage detector 21 for detecting a bridge voltage of the strain gauge. The voltage detector 21 includes a signal line 22 for applying a voltage to the bridge circuit and transmitting a signal corresponding to the detected bridge voltage to the outside, and is attached to the outer periphery of the outer ring 19. The outer ring 19 is provided with a plurality of mounting holes 19a at equal intervals on the circumference, and bolts B and nuts N are connected to a connecting member 30 that holds the left end of the test piece T in FIG. Can be connected by.

  In this example, the first insulator 18 is made of hard rubber, and electromagnetically isolates the detection unit 20 attached thereto and the voltage detection unit 21 attached to the outer periphery of the outer ring 19 from the electric linear actuator A. doing. Therefore, electromagnetic noise generated by energization of the coil 5 of the electric linear actuator A is not transmitted to the load sensor L via the inner rod 8, the cover 12, the mounting shaft 14 and the inner ring 17. In this case, the first insulator 18 functions not only as an elastically deforming part for the load sensor L to detect the load, but also to input electromagnetic noise from the electric linear actuator A side to the load sensor L. It also functions as an insulating member. The material and thickness of the first insulator 18 can be arbitrarily set on the assumption that the load sensor L can be electromagnetically insulated. The strain gauge is generally formed by attaching a resistance wire or a photo-etched resistance foil on a thin electric insulator base, but the base constituting the strain gauge cannot insulate magnetic noise, The base is not included in the insulating member I according to the present invention.

  The connecting member 30 includes a flange portion 30a and a chuck portion 30b that is provided to the right of the flange portion 30a in FIG. 1 and grips the left end of the test piece T as an external member. In the flange portion 30a, the same number of mounting holes 30c as the mounting holes 19a of the outer ring 19 are provided at positions corresponding to the mounting holes 19a.

  An insulating plate 31 is interposed between the connecting member 30 and the outer ring 19, and a bush 32 formed of an insulator is inserted into the mounting hole 30 c. The insulating plate 31 has a disc shape, and is provided at a position where the same number of mounting holes 31a as the mounting holes 19a of the outer ring 19 coincide with the mounting holes 19a. The bush 32 includes a cylindrical portion 32a that is inserted into the mounting hole 30c, and a flange portion 32b that is provided on the outer periphery of the right end of the cylindrical portion 32a in FIG. The length from the tip of the cylindrical portion 32a of the bush 32 to the flange portion 32b is the same as or slightly shorter than the length in the left-right direction in FIG.

  In order to attach the connecting member 30 to the electric linear actuator A, an insulating plate 31 is stacked on the outer ring 19, and a connecting member 30 in which a bush 32 is inserted into the mounting hole 30c from the right side in FIG. To do. Then, when the bolt B is inserted into the mounting holes 19a, 30c, 31a and the nut N is mounted on the outer periphery of the screw portion of the bolt B, the outer ring 19 and the connecting member 30 are tightened by the bolt B and the nut N. Are integrated together with the insulating plate 31 and the bush 32. When the outer ring 19 and the connecting member 30 are integrated in this way, the load sensor L is connected to the connecting member 30, and the load sensor L is connected to the electric linear actuator A as described above. 30 is connected to the electric linear actuator A through the load sensor L.

  In this example, the insulating plate 31 and the bush 32 are made of non-conductive and non-magnetized non-magnetic synthetic resin such as MC nylon (registered trademark). Are electrically insulated, and magnetically, a magnetic gap is formed between the components.

  An insulating plate 31 is interposed between the connecting member 30 and the load sensor L, and a bush 32 is provided to electromagnetically insulate between the bolt B and the connecting member 30. The load sensor L is electromagnetically insulated. Therefore, in this example, the second insulator 33 is formed by the insulating plate 31 and the bush 32. The thickness of the insulating plate 31 and the material and thickness of each part of the bush 32 can be arbitrarily set on the assumption that the load sensor L can be electromagnetically insulated.

  As described above, the load sensor L is connected to the electric linear actuator A via the first insulator 18 and is connected to the connecting member 30 via the second insulator 33. An insulating member I is constituted by the insulator 33.

  In the linear actuator unit 1 configured as described above, when the coil 5 is energized and the inner rod 8 is driven in the axial direction to expand and contract the electric linear actuator A, a vibration test can be performed by applying a tensile load to the test piece T. The load applied to the test piece T during the vibration test can be detected by the load sensor L.

  The insulating member I prevents electromagnetic noise from being input to the load sensor L from the inner rod 8 side of the electric linear actuator A. Further, in this example, electromagnetic noise is not input to the load sensor L from the electric linear actuator A through the frame 15, the chuck fitting 16, the test piece T, and the connecting member 30 by the insulating member I.

  Thus, since the load sensor L is electromagnetically insulated from the electric linear actuator A by the insulating member I, electromagnetic noise generated by energization of the electric linear actuator A is not superimposed on the signal output from the load sensor L. Therefore, according to the linear actuator unit 1, it is possible to prevent the electromagnetic noise from being superimposed on the output of the load sensor L, and an accurate load can be detected.

  In addition to the electric linear actuator A, the frame 15 that holds the electric linear actuator A, the chuck metal fitting 16, and the test piece T as an external member or the external member itself is made of a material that can be electromagnetically insulated. The second insulator 33 can be omitted. That is, if there is an electromagnetically insulating member on the path through which electromagnetic noise is indirectly input to the load sensor L from the electric linear actuator A or an external device (not shown) via the external member, the electric linear actuator A directly It is sufficient to provide the insulating member I on the path through which electromagnetic noise is input to the load sensor L. When the insulating member I electromagnetically insulates the load sensor L from both the electric linear actuator A and the connecting member 30 as in this example, the insulating member I is connected not only from the electric linear actuator A but also to the connecting member 30. There is an advantage that electromagnetic insulation can be performed from the external member side, and more accurate load can be detected.

  In addition, when the insulating member I is made of synthetic resin, there is an advantage that the linear actuator unit 1 can be reduced in weight while enabling electromagnetic insulation. Only one of the first insulator 18 and the second insulator 33 may be formed of synthetic resin.

  In this example, the load sensor L detects the elastic deformation amount of the first insulator 18. In contrast, like the linear actuator unit 40 shown in FIG. 2, the detection unit 20 of the load sensor L is provided between the inner ring 41, the outer ring 42, and the inner ring 41 and the outer ring 42. When detecting the amount of elastic deformation of the elastically deforming portion 43 of the conductor or magnetic material which is bent by the relative displacement of the inner ring 41 and the outer ring 42 in the axial direction, a cylindrical shape is formed between the inner ring 41 and the mounting shaft 14. The first insulator 44 may be interposed. In this example, the first insulator 44 and the second insulator 33 constitute an insulator member I ′. In this way, since the load sensor L is electromagnetically insulated from the electric linear actuator A, it is possible to prevent the electromagnetic noise from being superimposed on the output of the load sensor L and to detect an accurate load. Note that, among the components constituting the linear actuator unit 40 shown in FIG. 2, the components given the same reference numerals as those of the linear actuator unit 1 shown in FIG. 1 are composed of the same components as the linear actuator unit 1. Therefore, detailed explanation is omitted. In the example shown in FIG. 1, the first insulator 18 functions not only as an elastic deformation part for the load sensor L to detect the load, but also from the electric linear actuator A side with respect to the load sensor L. Since it functions also as an insulating member that cuts off the input of electromagnetic noise, it is not necessary to provide the first insulator in addition to the elastically deformable portion as in the example shown in FIG.

  Moreover, although the example in which the load sensor L is insulated by an insulating member so as not to be affected by electromagnetic noise from the outside has been described, the load sensor L includes a covering member formed of an insulating material that covers the detection unit 20 and the voltage detection unit 21. In addition, the load sensor L itself may be electromagnetically insulated from the outside.

  The linear actuator unit 1 can be used not only for the vibration tester K but also for various machines and devices if, for example, a bracket is provided in the connecting member 30 instead of the chuck portion 30b to enable connection with an external device. Therefore, the use of the linear actuator unit 1 is not limited to the vibration testing machine K. In addition to the attachment using the trunnion pins 2a and 2b, the linear actuator unit 1 may be provided with a bracket at the end of the bottom guide 6 so as to be connected to an external device.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

DESCRIPTION OF SYMBOLS 1 ... Linear actuator unit, 18 ... 1st insulator, 30 ... Connection member, 33 ... 2nd insulator, A ... Electric linear actuator, I, I '... Insulation member , L ... load sensor, T ... test piece (external member),

Claims (5)

An electric linear actuator;
A load sensor connected to the electric linear actuator to detect an axial load of the electric linear actuator;
An insulating member that electromagnetically insulates the load sensor from the electric linear actuator. The load sensor is connected to one end of the electric linear actuator;
A connecting member for connecting the electric linear actuator to an external member via the load sensor;
The linear actuator unit according to claim 1, wherein the insulating member electromagnetically insulates the load sensor from the connecting member. The linear actuator unit according to claim 1, wherein the insulating member is a synthetic resin. The insulating member is
A first insulator coupled to a tip of the electric linear actuator to electromagnetically insulate the load sensor from the electric linear actuator;
The linear actuator according to claim 2, further comprising a second insulator that is coupled to the coupling member and electromagnetically insulates the load sensor from the coupling member. unit. An electric linear actuator;
A load sensor connected to the electric linear actuator for detecting an axial load of the electric linear actuator;
The load sensor is electromagnetically insulated. The linear actuator unit characterized by the above-mentioned.

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