Clamping mechanism

Abstract

This provides a clamping mechanism that can hold an object without requiring a continuous energy supply. [Solution] The clamping mechanism comprises a fixed clamping claw supported by a housing, a movable clamping claw supported by a moving member, a first permanent magnet that attracts the moving member, a second permanent magnet that attracts the moving member in the opposite direction to the first permanent magnet, a first electromagnet positioned on the side of the first permanent magnet, and a second electromagnet positioned on the side of the second permanent magnet. After the moving member moves toward the first permanent magnet, if the first and second electromagnets are not energized, the magnetic field generated by the combination of the first permanent magnet and the first core of the first electromagnet maintains the state in which the moving member is attracted to the first permanent magnet. After the moving member moves toward the second permanent magnet, if the first and second electromagnets are not energized, the magnetic field generated by the combination of the second permanent magnet and the second core of the second electromagnet maintains the state in which the moving member is attracted to the second permanent magnet.

Description

Technical Field

[0001] The present invention relates to a clamping mechanism.

Background Art

[0002] As a mechanism for holding an object, an electric chuck disclosed in Patent Document 1 is known. This electric chuck has a rotating motor and a plurality of fingers moved by the motor, and these fingers hold the object. Also, an air chuck disclosed in Patent Document 2 is known. This air chuck has a piston driven by air and a plurality of gripping members moved by a motor, and these gripping members hold the object.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the electric chuck disclosed in Patent Document 1, in order to maintain the state where the fingers clamp the object, power must be continuously supplied to the motor. Otherwise, the motor can rotate reversely, and the fingers cannot continue to clamp the object. In the air chuck disclosed in Patent Document 2, in order to maintain the state where the gripping members clamp the object, air force must be continuously applied to the piston. Otherwise, the piston can move reversely, and the gripping members cannot continue to clamp the object.

[0005] Therefore, the present invention provides a clamping mechanism that can continue to hold an object without continuously supplying energy. [Means for solving the problem]

[0006] A clamping mechanism is provided according to one aspect of the present invention. The clamping mechanism comprises a movable member, a housing that movably supports the movable member, a fixed clamping claw supported by the housing, a movable clamping claw supported by the movable member and cooperating with the fixed clamping claw to hold an object, a first permanent magnet disposed within the housing and generating a magnetic field in a direction that attracts the movable member so that the movable clamping claw approaches the fixed clamping claw, a second permanent magnet disposed within the housing and generating a magnetic field in a direction that attracts the movable member so that the movable clamping claw moves away from the fixed clamping claw, a first electromagnet disposed within the housing and having a first core and a first coil wound around the first core, with the first core interposed between the first permanent magnet and the movable member, and a second electromagnet disposed within the housing and having a second core and a second coil wound around the second core, with the second core interposed between the second permanent magnet and the movable member. If the first electromagnet is energized to strengthen the magnetic field of the first permanent magnet, the first electromagnet moves the moving member toward the first core. If the second electromagnet is energized to strengthen the magnetic field of the second permanent magnet, the second electromagnet moves the moving member toward the second core. After the moving member has moved toward the first core, if the first and second electromagnets are not energized, the magnetic field generated by the combination of the first permanent magnet and the first core maintains the state in which the moving member is attracted to the first core. After the moving member has moved toward the second core, if the first and second electromagnets are not energized, the magnetic field generated by the combination of the second permanent magnet and the second core maintains the state in which the moving member is attracted to the second core.

[0007] In this embodiment, when one electromagnet is excited to strengthen the magnetic field of the corresponding permanent magnet, the excited electromagnet moves the moving member toward itself. After the moving member has moved toward one of the electromagnets, the permanent magnet and core corresponding to the previously excited electromagnet attract the moving member, keeping it stationary while both electromagnets are not excited. Therefore, the clamping mechanism can hold an object without a continuous energy supply, and can keep the movable clamping claws separated from the fixed clamping claws without a continuous energy supply, thus saving energy. Furthermore, the clamping mechanism can hold an object even in the event of a power outage, for example.

[0008] Preferably, the moving member, the fixed clamping claw, and the movable clamping claw are formed from a non-magnetic material. The clamping mechanism may further include a first ferromagnetic member and a second ferromagnetic member, which are formed from a ferromagnetic material and are positioned at both ends of the moving member in the direction of movement. The first core may be interposed between the first permanent magnet and the first ferromagnetic member, and the second core may be interposed between the second permanent magnet and the second ferromagnetic member. In this case, if the magnetic force with which the first permanent magnet and the first electromagnet attract the first ferromagnetic member is greater than the magnetic force with which the second permanent magnet and the second electromagnet attract the second ferromagnetic member, the moving member will be attracted to the first permanent magnet. Conversely, if the magnetic force with which the second permanent magnet and the second electromagnet attract the second ferromagnetic member is greater than the magnetic force with which the first permanent magnet and the first electromagnet attract the first ferromagnetic member, the moving member will be attracted to the second permanent magnet. Since the moving member, fixed clamp claw, and movable clamp claw are made of non-magnetic material, they do not emit magnetic flux. Therefore, the magnetic fields generated by the permanent magnets and electromagnets can be effectively utilized for position control of the moving member.

[0009] Preferably, the housing comprises a ferromagnetic wall portion formed from a ferromagnetic material, which is arranged around the first permanent magnet, the first coil, the second permanent magnet, and the second coil, and a non-magnetic wall portion formed from a non-magnetic material, which is arranged around the portion of the movable member that supports the movable clamp claw. In this case, the ferromagnetic wall surrounding the permanent magnet and coil functions as a yoke, allowing magnetic flux to pass through and strengthening the magnetic field. Furthermore, the non-magnetic wall, moving member, fixed clamp claw, and movable clamp claw, which are separated from the permanent magnet and coil, are made of non-magnetic material and therefore do not emit magnetic flux. Consequently, the magnetic field generated by the permanent magnet and electromagnet can be effectively utilized for position control of the moving member.

[0010] Preferably, the clamping mechanism further includes a control device for controlling the excitation of the first electromagnet and the second electromagnet. Preferably, when the first electromagnet is excited to strengthen the magnetic field of the first permanent magnet, the control device excites the second electromagnet to weaken the magnetic field of the second permanent magnet, and when the second electromagnet is excited to strengthen the magnetic field of the second permanent magnet, the control device excites the first electromagnet to weaken the magnetic field of the first permanent magnet. In this case, when the moving member is moved, the energy that needs to be supplied to the electromagnet that attracts the moving member can be reduced because the magnetic field of the permanent magnet on the opposite side is weakened.

[0011] Preferably, the clamping mechanism further includes a control device for controlling the excitation of the first electromagnet and the second electromagnet. Preferably, the control device does not excite the second electromagnet when it excites the first electromagnet to strengthen the magnetic field of the first permanent magnet, and does not excite the first electromagnet when it excites the second electromagnet to strengthen the magnetic field of the second permanent magnet. In this case, the moving member can be moved by exciting only the electromagnet that attracts the moving member.

[0012] Preferably, the clamping mechanism further includes a sensor for measuring the force or acceleration applied to the housing. Preferably, when the object is held between the fixed clamping claw and the movable clamping claw and the first and second electromagnets are not energized, the control device energizes the first electromagnet to increase the clamping force applied by the movable clamping claw to the object if the force or acceleration measured by the sensor exceeds a threshold. This clamping mechanism can hold an object between the fixed and movable clamping claws without a continuous energy supply. The first electromagnet does not need to be energized while the object is held between the fixed and movable clamping claws. However, if a large force or acceleration is temporarily applied to the housing, energizing the first electromagnet, which provides clamping force to the movable clamping claws, allows the fixed and movable clamping claws to hold the object more strongly, preventing it from falling or shifting.

[0013] Preferably, the clamping mechanism further includes a sensor for measuring the force or acceleration applied to the housing. Preferably, if the force or acceleration measured by the sensor is greater than a threshold, the control device continues to energize the first electromagnet for the period during which the movable clamping claw is to be held close to the fixed clamping claw. In this case, if a large force or acceleration is applied to the housing, the first electromagnet that provides clamping force to the movable clamping claws is kept energized for the duration that the object should be held. This prevents the clamping force from weakening during the period that the object should be held, thus preventing the object from falling or shifting position. [Effects of the Invention]

[0014] In this embodiment, the clamping mechanism continues to hold the object even without a continuous supply of energy. [Brief explanation of the drawing]

[0015] [Figure 1]FIG. 1 is a cross-sectional view of a clamp mechanism according to an embodiment of the present invention in a state of holding an object. [Figure 2] FIG. 2 is a cross-sectional view of the clamp mechanism in a state of releasing the object. [Figure 3] FIG. 3 is a perspective view showing a modification example of a clamp claw of the clamp mechanism. [Figure 4] FIG. 4 is a perspective view showing another modification example of the clamp claw of the clamp mechanism. [Figure 5] FIG. 5 is a flowchart showing an example of a method of using the clamp mechanism. [Figure 6] FIG. 6 is a cross-sectional view of a clamp mechanism according to a modification example of an embodiment of the present invention. [Figure 7] FIG. 7 is a flowchart showing an example of a method of using the clamp mechanism according to the modification example of FIG. 6. [Figure 8] FIG. 8 is a flowchart showing another example of a method of using the clamp mechanism according to the modification example of FIG. 6.

MODE FOR CARRYING OUT THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The scales of the drawings are not necessarily accurate, and some features may be exaggerated or omitted. In the following description, "upper", "lower", "left", and "right" are based on the drawings and are not intended to limit the orientation during the use of the clamp mechanism.

[0017] The clamp mechanism according to an embodiment of the present invention is provided, for example, on a robot arm to carry an object. Alternatively, this clamp mechanism is provided, for example, on an index table to hold an object. This clamp mechanism can also be called a "gripper" or a "chuck".

[0018] As shown in FIGS. 1 and 2, the clamp mechanism according to an embodiment of the present invention includes an actuator assembly 1 and a control device 40. The actuator assembly 1 includes a movable member 2, a housing 3, a fixed clamp claw 4, and a movable clamp claw 5.

[0019] The movable member 2 is made of a non-magnetic material (e.g., aluminum, non-magnetic stainless steel, plastic). The portion of the movable member 2 other than the movable clamp claw 5 may have a rectangular prism shape, for example, but may also have a cylindrical shape.

[0020] The movable member 2 is positioned inside the housing 3. The housing 3 supports the movable member 2 so that it can move along its longitudinal direction. The parts of the housing 3 other than the fixing clamp claws 4 have, for example, a rectangular tube shape, but may also have a cylindrical shape.

[0021] The housing 3 supports the fixing clamp claws 4. In this embodiment, the fixing clamp claws 4 are formed on the upper part 33a of the wall portion 33 that constitutes the housing 3. However, the fixing clamp claws 4 may be fixed to a member (not shown) that is fixed to the housing 3. The fixing clamp claws 4 extend in the direction opposite to that of the movable member 2.

[0022] The movable clamp claw 5 is supported on the movable member 2. In this embodiment, the movable clamp claw 5 is formed on the movable member 2. However, the movable clamp claw 5 may be fixed to a member (not shown) that is fixed to the movable member 2. The movable clamp claw 5 passes through a through hole 33b formed in the upper part 33a of the wall portion 33 that constitutes the housing 3, and faces the fixed clamp claw 4. As the movable member 2 moves, the distance between the fixed clamp claw 4 and the movable clamp claw 5 is variable. When the movable clamp claw 5 approaches the fixed clamp claw 4, the fixed clamp claw 4 and the movable clamp claw 5 cooperate to hold the object 7. When the movable clamp claw 5 moves away from the fixed clamp claw 4, the object 7 is released from the fixed clamp claw 4 and the movable clamp claw 5.

[0023] The clamping claws 4 and 5 shown in the illustration have a shape suitable for gripping spherical or circular objects 7. However, the shape of the clamping claws 4 and 5 is not limited to those shown. The clamping claws 4 and 5 may have other shapes as illustrated in Figure 3 or Figure 4.

[0024] As shown in Figures 1 and 2, the housing 3 has multiple pieces, namely wall sections 31, 32, 33, 34, and 35. Wall section 31 is an end wall located at the left end of the housing 3, and wall section 35 is an end wall located at the right end of the housing 3. Each of the wall sections 32, 33, and 34 is a circumferential wall and may have, for example, a rectangular tube shape, but may also have a cylindrical shape. The movable member 2 is moved back and forth inside wall section 33. Although not absolutely necessary, a lubricant such as grease may be placed inside wall section 33 to facilitate the movement of the movable member 2. The wall sections 31, 32, 33, 34, and 35 are connected to each other by fasteners or connectors (e.g., screws) not shown. Furthermore, for attachment to the external structure, the mounting pieces 37 and 38 are fixed to the housing 3 by fasteners or connectors (e.g., screws) not shown. Mounting holes 37a and 38a are formed in the mounting pieces 37 and 38, respectively, to facilitate attachment to the external structure. The mounting pieces 37 and 38, and thus the actuator assembly 1, are attached to the external structure by fasteners or connectors (e.g., bolts) not shown, which are inserted into the mounting holes 37a and 38a. Mounting piece 37 is fixed to the left side of the left wall 31, and mounting piece 38 is fixed to the right side of the right wall 35. However, the position of the mounting pieces is not limited to the illustrated embodiment; for example, mounting piece 37 may be fixed to the lower surface of the wall 31, and mounting piece 38 may be fixed to the lower surface of the wall 35.

[0025] Inside the housing 3, a first magnet set 10a and a second magnet set 10b are arranged to move and position the movable member 2 together with the movable clamp claw 5. The first magnet set 10a is located on the left side of the housing 3 and, as shown in Figure 1, pulls the movable member 2 to the left. The second magnet set 10b is located on the right side of the housing 3 and, as shown in Figure 2, pulls the movable member 2 to the right. A first ferromagnetic member 11 and a second ferromagnetic member 12 are fixed to the left and right ends of the movable member 2, respectively, so that it can be moved and positioned left and right by the magnetic force of the magnet sets 10a and 10b. The ferromagnetic members 11 and 12 are made of a ferromagnetic material (for example, iron). The ferromagnetic members 11 and 12 may be the same shape and size as each other.

[0026] The first magnet set 10a includes a first permanent magnet 13a and a first electromagnet 14a. The first permanent magnet 13a is located within the wall portion 31. The first electromagnet 14a is located within the wall portion 32. The first electromagnet 14a includes a first core 15a and a first coil 16a wound around the first core 15a, with the first core 15a interposed between the first permanent magnet 13a and the first ferromagnetic member 11. The first permanent magnet 13a generates a magnetic field Fa that attracts the first ferromagnetic member 11, which is attached to the left end of the moving member 2, to the left. The first core 15a is made of a ferromagnetic material (e.g., iron). The first core 15a may be fixed at a position away from the first permanent magnet 13a, but preferably it is attracted to the first permanent magnet 13a and in contact with it. Therefore, even if the first coil 16a is not energized and the first electromagnet 14a is not energized, the combination of the first permanent magnet 13a and the first core 15a generates a magnetic field Fa that attracts the moving member 2 to the left.

[0027] The second magnet set 10b includes a second permanent magnet 13b and a second electromagnet 14b. The second permanent magnet 13b is located within the wall portion 35. The second electromagnet 14b is located within the wall portion 34. The second electromagnet 14b includes a second core 15b and a second coil 16b wound around the second core 15b, with the second core 15b interposed between the second permanent magnet 13b and the second ferromagnetic member 12. The second permanent magnet 13b generates a magnetic field Fb that attracts the second ferromagnetic member 12, which is attached to the right end of the moving member 2, to the right. The second core 15b is made of a ferromagnetic material (e.g., iron). The second core 15b may be fixed at a position away from the second permanent magnet 13b, but preferably it is attracted to the second permanent magnet 13b and in contact with it. Therefore, even if the second coil 16b is not energized and the second electromagnet 14b is not energized, the combination of the second permanent magnet 13b and the second core 15b generates a magnetic field Fb that attracts the moving member 2 to the right.

[0028] The magnetic force of the second permanent magnet 13b may be equivalent to that of the first permanent magnet 13a. The second core 15b may be the same shape and size as the first core 15a, and the dimensions of the wires constituting the second coil 16b and the number of turns of the second coil 16b may be the same as those of the wires constituting the first coil 16a and the number of turns of the first coil 16a. Therefore, the magnetic force that the second electromagnet 14b can generate may be the same as that of the first electromagnet 14a.

[0029] Through holes 17 and 18 are formed in the wall portion 32 of the housing 3, and insulated wires 19 and 20, which have the conductors at both ends of the first coil 16a, are passed through the through holes 17 and 18, respectively. Through holes 21 and 22 are formed in the wall portion 34 of the housing 3, and insulated wires 23 and 24, which have the conductors at both ends of the second coil 16b, are passed through the through holes 21 and 22, respectively. The insulated conductors 19, 20, 23, and 24 are electrically connected to the control device 40.

[0030] The control device 40 includes, for example, a processor and a memory device, and the processor operates according to a computer program. The control device 40 may also be a programmable logic device such as an FPGA (Field Programmable Gate Array) or a DSP (Digital Signal Processor). According to the program, the control device 40 can control the excitation of the first electromagnet 14a and the second electromagnet 14b by controlling the power supply to the coils 16a and 16b.

[0031] The insulated conductors 19, 20, 23, and 24 may be directly connected to the control device 40. However, the control device 40 may also control the power supply to the coils 16a and 16b using wireless power supply technology, thereby controlling the excitation of the first electromagnet 14a and the second electromagnet 14b.

[0032] In the above configuration, if the magnetic force with which the first magnet set 10a attracts the first ferromagnetic member 11 is greater than the magnetic force with which the second magnet set 10b attracts the second ferromagnetic member 12, the moving member 2 is attracted to the first magnet set 10a on the left. Conversely, if the magnetic force with which the second magnet set 10b attracts the second ferromagnetic member 12 is greater than the magnetic force with which the first magnet set 10a attracts the first ferromagnetic member 11, the moving member 2 is attracted to the second magnet set 10b on the right. Therefore, the moving member 2 is moved back and forth within the internal space of the wall portion 33. In the illustrated embodiment, the reciprocating motion of the moving member 2 is linear, but it may also be curved.

[0033] In order to effectively utilize the magnetic flux of the magnet sets 10a and 10b, the walls 31, 32, 34, and 35 of the housing 3 are ferromagnetic walls formed from a ferromagnetic material (for example, iron). As described above, the wall portion 31 is positioned around the first permanent magnet 13a, and the wall portion 32 is positioned around the first coil 16a. In the illustrated embodiment, the wall portions 31 and 32 are separate components, but they may be formed integrally. The wall portion 31 positioned around the first permanent magnet 13a and the wall portion 32 positioned around the first coil 16a function as yokes through which magnetic flux passes, thereby strengthening the magnetic field Fa of the first magnet set 10a. The wall portion 35 is positioned around the second permanent magnet 13b, and the wall portion 34 is positioned around the second coil 16b. In the illustrated embodiment, the walls 34 and 35 are separate components, but they may be formed integrally. The wall portion 35 positioned around the second permanent magnet 13b and the wall portion 34 positioned around the second coil 16b function as yokes through which magnetic flux passes, thereby strengthening the magnetic field Fb of the second magnet set 10b.

[0034] Furthermore, in order to prevent or reduce the divergence of magnetic flux from the magnet sets 10a and 10b, the wall portion 33 is a non-magnetic wall portion formed from a non-magnetic material (e.g., aluminum, non-magnetic stainless steel, plastic). In the illustrated embodiment, the entire wall portion 33 arranged around the moving member 2 is a non-magnetic wall portion over the entire stroke of the moving member 2, but it is preferable that at least the portion of the moving member 2 that supports the movable clamp claw 5 is a non-magnetic wall portion. Furthermore, the movable member 2, the fixed clamp claw 4, and the movable clamp claw 5 are made of non-magnetic material. Since the non-magnetic wall portion 33, the movable member 2, the fixed clamp claw 4, and the movable clamp claw 5, which are located away from the permanent magnets 13a, 13b and the coils 16a, 16b, are made of non-magnetic material, they do not emit magnetic flux. Therefore, the magnetic fields Fa and Fb generated by the permanent magnets 13a, 13b and the electromagnets 14a, 14b can be effectively utilized for position control of the movable member 2. To prevent or reduce magnetic flux divergence, preferably, the mounting pieces 37 and 38 are also formed from a non-magnetic material.

[0035] Under the above configuration, the control device 40 controls the excitation of the electromagnets 14a and 14b to move and position the movable member 2, and the clamping claws 4 and 5 can hold and release the object 7. Below, an example of the control method by the control device 40, i.e., the method of using the clamping mechanism, will be explained with reference to the flowchart in Figure 5.

[0036] At the start of Figure 5, as shown in Figure 2, the movable member 2 is attracted to the second magnet set 10b, and the movable clamp claw 5 is separated from the fixed clamp claw 4. First, in step S1, the control device 40 determines whether or not the clamping mechanism should hold the object 7. If the determination in step S1 is positive, the operation proceeds to step S2.

[0037] In order to hold the object 7 with the clamp claws 4 and 5, in step S2, the control device 40 energizes the first coil 16a to strengthen the magnetic field Fa of the first permanent magnet 13a, thereby energizing the first electromagnet 14a. At this time, the control device 40 may also energize the second coil 16b to weaken (for example, cancel out) the magnetic field Fb of the second permanent magnet 13b, thereby energizing the second electromagnet 14b, or it may not energize the second electromagnet 14b by not energizing the second coil 16b. As a result, the magnetic field Fa of the first magnet set 10a attracts the first ferromagnetic member 11, which overcomes the magnetic field Fb of the second magnet set 10b attracts the second ferromagnetic member 12. As shown in Figure 1, the movable clamp claw 5 and the moving member 2 move to the left, i.e., toward the first core 15a. Consequently, the movable clamp claw 5 approaches the fixed clamp claw 4, and the object 7 is held between them.

[0038] The dimensions of the relevant parts of the actuator assembly 1 are designed such that a gap CL remains between the first ferromagnetic member 11 and the first core 15a when the clamping claws 4 and 5 hold the object 7 (see Figure 1). Therefore, the clamping claws 4 and 5 can hold the object 7 with a reasonably large force. However, the gap CL is not absolutely necessary. When the clamping claws 4 and 5 hold the object 7, the first ferromagnetic member 11 may come into contact with the first core 15a.

[0039] Once the first ferromagnetic member 11 approaches the first core 15a together with the movable member 2, the magnetic field Fa generated by the combination of the first permanent magnet 13a and the first core 15a maintains the state in which the first ferromagnetic member 11 and the movable member 2 are attracted to the first core 15a, even if the first electromagnet 14a is not energized. In other words, even if the magnetic force component from the first electromagnet 14a disappears, the movable member 2 remains stationary, the movable clamp claw 5 continues to approach the fixed clamp claw 4, and the clamp claws 4 and 5 can continue to hold the object 7. Therefore, in step S3, the control device 40 does not energize the first electromagnet 14a and the second electromagnet 14b.

[0040] Next, in step S4, the control device 40 determines whether or not to release the object 7 from the clamping mechanism. If the determination in step S4 is positive, the operation proceeds to step S5.

[0041] In order to release the object 7 from the clamping claws 4 and 5, in step S5, the control device 40 energizes the second coil 16b to strengthen the magnetic field Fb of the second permanent magnet 13b, thereby energizing the second electromagnet 14b. At this time, the control device 40 may also energize the first coil 16a to weaken (for example, cancel) the magnetic field Fa of the first permanent magnet 13a, thereby energizing the first electromagnet 14a, or it may not energize the first electromagnet 14a by not energizing the first coil 16a. As a result, the magnetic field Fb of the second magnet set 10b attracts the second ferromagnetic member 12, which overcomes the magnetic field Fa of the first magnet set 10a that attracts the first ferromagnetic member 11. As shown in Figure 2, the moving member 2 moves to the right, i.e., toward the second core 15b, together with the movable clamp claw 5. Consequently, the movable clamp claw 5 separates from the fixed clamp claw 4, and the object 7 is released from between them.

[0042] Once the second ferromagnetic member 12 approaches the second core 15b together with the movable member 2, the magnetic field Fb generated by the combination of the second permanent magnet 13b and the second core 15b maintains the state in which the second ferromagnetic member 12 and the movable member 2 are attracted to the second core 15b, even if the second electromagnet 14b is not energized. In other words, even if the magnetic force component from the second electromagnet 14b disappears, the movable member 2 remains stationary, and the movable clamp claw 5 can continue to move away from the fixed clamp claw 4. Therefore, in step S6, the control device 40 does not energize the first electromagnet 14a and the second electromagnet 14b.

[0043] Next, in step S7, the control device 40 determines whether or not a termination command has been supplied to the control device 40 itself. If no termination command is received, the operation returns to step S1, as it waits until the clamp claws 4 and 5 are ready to hold a new object 7. If a termination command is received, the operation ends.

[0044] In this clamping mechanism, when one electromagnet 14a or 14b is excited to strengthen the magnetic field of the corresponding permanent magnet 13a or 13b, the excited electromagnet 14a or 14b moves the moving member 2 toward itself (steps S2, S5). After the moving member 2 has moved toward one of the electromagnets 14a or 14b, while both electromagnets 14a or 14b are not excited, the permanent magnet 13a or 13b and core 15a or 15b corresponding to the immediately excited electromagnet 14a or 14b attract the moving member 2, and the moving member 2 is kept stationary (steps S3, S6). Therefore, the clamping mechanism can continue to hold the object 7 without a continuous energy supply, and can keep the movable clamping claw 5 away from the fixed clamping claw 4 without a continuous energy supply, thus saving energy. Furthermore, for example, the clamping mechanism can continue to hold the object 7 even in the event of a power outage.

[0045] In step S2, the second electromagnet 14b is energized to weaken the magnetic field Fb of the second permanent magnet 13b, and in step S5, the first electromagnet 14a is energized to weaken the magnetic field Fa of the first permanent magnet 13a. When the moving member 2 is moved, the energy that must be supplied to the electromagnet 14a or 14b that attracts the moving member 2 can be reduced because the magnetic field of the permanent magnet 13b or 13a on the opposite side is weakened. If the second electromagnet 14b is not energized in step S2, and the first electromagnet 14a is not energized in step S5, the moving member 2 can be moved by energizing only the electromagnet 14a or 14b that attracts the moving member 2.

[0046] Figure 6 shows a modified clamping mechanism according to an embodiment of the present invention. This clamping mechanism further includes a sensor 41 in addition to the components according to the embodiment. The sensor 41 is attached to one of the locations on the housing 3 and measures the force or acceleration applied to the housing 3. The sensor 41 supplies a signal indicating the force or acceleration applied to the housing 3 to the control device 40. In other words, the sensor 41 reports the force or acceleration applied to the housing 3 to the control device 40.

[0047] Figure 6 shows the state in which the clamp claws 4 and 5 are holding object 7. The figure showing the state in which object 7 is released is the same as in Figure 2, except for sensor 41.

[0048] When an object 7 is held between the fixed clamp claw 4 and the movable clamp claw 5, and the first electromagnet 14a and the second electromagnet 14b are not energized, the control device 40 energizes the first electromagnet 14a to increase the clamping force that the movable clamp claw 5 applies to the object 7 if the force or acceleration measured by the sensor 41 exceeds a threshold.

[0049] Referring to the flowchart in Figure 7, an example of the control method by the control device 40 according to the modified example in Figure 6, i.e., the method of using the clamping mechanism, will be explained. Steps indicated with the same numbers as in Figure 5 are the same as the steps explained with reference to Figure 5. After step S3, the clamping mechanism is in a state where the object 7 is held between the fixed clamping claw 4 and the movable clamping claw 5, and the first electromagnet 14a and the second electromagnet 14b are not energized. In step S8, the control device 40 compares the force or acceleration reported by the sensor 41 with a threshold. If the force or acceleration is greater than the threshold, in step S9, the control device 40 energizes the first electromagnet 14a by supplying power to the first coil 16a to strengthen the magnetic field Fa of the first permanent magnet 13a. At this time, the control device 40 may also energize the second electromagnet 14b by supplying power to the second coil 16b to weaken (e.g., cancel) the magnetic field Fb of the second permanent magnet 13b, or it may not energize the second electromagnet 14b by not supplying power to the second coil 16b. The process in step S9 may be the same as in step S2. However, the current supplied to the first coil 16a in step S9 may be different from the current supplied to the first coil 16a in step S2.

[0050] In step S9, the magnetic field Fa of the first magnet set 10a increases again, attracting the first ferromagnetic member 11. Therefore, if a large force or acceleration is temporarily applied to the housing 3, the magnetic field Fa is increased by exciting the first electromagnet 14a that provides clamping force to the movable clamp claw 5, allowing the fixed clamp claw 4 and the movable clamp claw 5 to hold the object 7 more strongly and prevent the object 7 from falling or shifting position.

[0051] The process then proceeds to step S4. If the judgment in step S8 is negative (the force or acceleration reported from sensor 41 is below the threshold), the process also proceeds to step S4. During the period when the judgment in step S4 is negative (object 7 should not be released), if the force or acceleration reported by sensor 41 falls below a threshold, the control device 40 may, as in step S3, refrain from exciting the first electromagnet 14a and the second electromagnet 14b. That is, if no large force or acceleration is applied to the housing 3, the magnetic force component from the first electromagnet 14a may be extinguished. This threshold may be the same as or different from the threshold in step S8. In this case, the magnetic field Fa generated by the combination of the first permanent magnet 13a and the first core 15a keeps the moving member 2 stationary, the movable clamp claw 5 continues to approach the fixed clamp claw 4, and the clamp claws 4 and 5 continue to hold the object 7.

[0052] Referring to the flowchart in Figure 8, another example of the control method by the control device 40 according to the modified example in Figure 6, i.e., the method of using the clamping mechanism, will be explained. Steps indicated with the same numbers as in Figure 5 are the same as the steps explained with reference to Figure 5. At the start of Figure 8, as shown in Figure 2, the movable member 2 is attracted to the second magnet set 10b, and the movable clamp claw 5 is separated from the fixed clamp claw 4.

[0053] First, in step S10, the control device 40 compares the force or acceleration reported by the sensor 41 with a threshold. If the force or acceleration is greater than the threshold, in step S11, the control device 40 sets a flag stored in the control device 40 itself to 1. If the force or acceleration is less than or equal to the threshold, in step S12, the control device 40 resets the flag to 0. After steps S11 and S12, the operation proceeds to step S1, and the control device 40 waits until it is ready to hold the object 7 with the clamping claws 4 and 5.

[0054] In step S2, the movable member 2 is moved to the left together with the movable clamp claw 5 in order to hold the object 7 with the clamp claws 4 and 5, and then the operation proceeds to step S13. In step S13, the control device 40 determines whether the flag is 1 or not. If the determination in step S13 is negative (force or acceleration is below the threshold), the operation proceeds to step S3. Therefore, the control device 40 does not energize the first electromagnet 14a and the second electromagnet 14b. Because the force or acceleration applied to the actuator assembly 1 is small, the movable clamp claw 5 continues to approach the fixed clamp claw 4, and the clamp claws 4 and 5 can continue to hold the object 7.

[0055] If the judgment in step S13 is positive (force or acceleration is greater than the threshold), the operation proceeds to step S4 without going through step S3, and the control device 40 waits until it is time to release the object 7 from the clamp claws 4 and 5. Therefore, if the force or acceleration measured by the sensor 41 is greater than the threshold, the control device 40 continues to energize the first electromagnet 14a, which brings the movable clamp claw 5 closer to the fixed clamp claw 4, for the period during which the object 7 should be held. During this period during which the object 7 should be held, the control device 40 may energize the second electromagnet 14b to weaken the magnetic field Fb, or it may not energize the second electromagnet 14b. Even if a large force or acceleration is applied to the housing 3, the clamping force is not weakened by the strong magnetic field Fa during the period during which the object 7 should be held, thus preventing the object 7 from falling or shifting position. In addition, the strong magnetic field Fa prevents vibration of the moving member 2 and reduces the mutual impact between the moving member 2 and the wall 33.

[0056] In step S5, the movable member 2 is moved to the right together with the movable clamp claw 5 to release the object 7 from the clamp claws 4 and 5, and then the operation proceeds to step S14. In step S14, the control device 40 determines whether the flag is 1 or not. If the determination in step S14 is negative (force or acceleration is below the threshold), the operation proceeds to step S6. Therefore, the control device 40 does not energize the first electromagnet 14a and the second electromagnet 14b. Because the force or acceleration applied to the actuator assembly 1 is small, the movable clamp claw 5 can remain separated from the fixed clamp claw 4.

[0057] If the determination in step S14 is positive (force or acceleration is greater than the threshold), the operation proceeds to step S7 without going through step S6, and the control device 40 determines whether or not a termination command has been supplied to the control device 40 itself. Therefore, if the force or acceleration measured by the sensor 41 is greater than the threshold, the control device 40 continues to energize the second electromagnet 14b that separates the movable clamp claw 5 from the fixed clamp claw 4 for the period during which the movable clamp claw 5 should be separated from the fixed clamp claw 4. During this period, the control device 40 may energize the first electromagnet 14a to weaken the magnetic field Fa, or it may not energize the first electromagnet 14a. Even if a large force or acceleration is applied to the housing 3, the strong magnetic field Fb prevents vibration of the moving member 2 and reduces the mutual impact between the moving member 2 and the wall 33 during the period during which the movable clamp claw 5 should be separated from the fixed clamp claw 4.

[0058] In step S7, the control device 40 determines whether or not a termination command has been issued to the control device 40 itself. If no termination command has been issued, the operation returns to step S10, and the control device 40 again compares the force or acceleration reported from the sensor 41 with the threshold. If a termination command has been issued, the operation terminates.

[0059] Although the present invention has been illustrated and described above with reference to preferred embodiments, those skilled in the art will understand that modifications to form and detail are possible without departing from the scope of the invention as described in the claims. Such modifications, alterations, and changes should be included within the scope of the present invention. [Explanation of Symbols]

[0060] 1…Actuator assembly, 2…Moving member, 3…Housing, 4…Fixed clamp claw, 5…Movable clamp claw, 7…Object, 10a…First magnet set, 10b…Second magnet set, 11…First ferromagnetic member, 12…Second ferromagnetic member, 13a…First permanent magnet, 13b…Second permanent magnet, 14a…First electromagnet, 14b…Second electromagnet, 15a…First core, 15b…Second core, 16a...First coil, 16b...Second coil, 17,18...Through holes, 19,20...Insulated wires, 21,22...Through holes, 23,24...Insulated wires, 31,32,34,35...Wall section (ferromagnetic wall section), 33...Wall section (non-magnetic wall section), 33a...Upper part, 33b...Through hole, 37,38...Mounting piece, 37a,38a...Mounting hole, 40...Control device, 41...Sensor, Fa...Magnetic field, Fb...Magnetic field, CL...Gap

Claims

1. A movable member and A housing that movably supports the aforementioned movable member, The housing is supported by a fixing clamp claw, A movable clamp claw, supported by the aforementioned moving member and cooperating with the fixed clamp claw to hold an object, A first permanent magnet is disposed within the housing and generates a magnetic field in a direction that attracts the moving member so that the movable clamp claw approaches the fixed clamp claw, A second permanent magnet is disposed within the housing and generates a magnetic field in a direction that attracts the moving member so that the movable clamp claw moves away from the fixed clamp claw, Displaced within the housing, the first electromagnet comprises a first core and a first coil wound around the first core, the first core being interposed between the first permanent magnet and the moving member, Displaced within the housing, the second electromagnet comprises a second core and a second coil wound around the second core, wherein the second core is interposed between the second permanent magnet and the moving member. Equipped with, When the first electromagnet is excited to strengthen the magnetic field of the first permanent magnet, the first electromagnet moves the moving member toward the first core, and when the second electromagnet is excited to strengthen the magnetic field of the second permanent magnet, the second electromagnet moves the moving member toward the second core. If the first electromagnet and the second electromagnet are not energized after the moving member has moved toward the first core, the magnetic field generated by the combination of the first permanent magnet and the first core is configured to maintain the state in which the moving member is attracted to the first core. If the first electromagnet and the second electromagnet are not energized after the moving member has moved toward the second core, the magnetic field generated by the combination of the second permanent magnet and the second core is configured to maintain the state in which the moving member is attracted to the second core. Clamping mechanism.

2. The moving member, the fixed clamp claw, and the movable clamp claw are formed from a non-magnetic material. The device further comprises a first ferromagnetic member and a second ferromagnetic member, formed from a ferromagnetic material and positioned at both ends of the moving member in the direction of movement, wherein the first core is interposed between the first permanent magnet and the first ferromagnetic member, and the second core is interposed between the second permanent magnet and the second ferromagnetic member. The clamping mechanism according to claim 1.

3. The aforementioned housing is A ferromagnetic wall portion formed from a ferromagnetic material is arranged around the first permanent magnet, around the first coil, around the second permanent magnet, and around the second coil. It comprises a non-magnetic wall portion formed from a non-magnetic material, which is arranged around the portion of the movable member that supports the movable clamp claw. The clamping mechanism according to claim 1 or 2.

4. The system further includes a control device for controlling the excitation of the first electromagnet and the second electromagnet, When the control device energizes the first electromagnet to strengthen the magnetic field of the first permanent magnet, it energizes the second electromagnet to weaken the magnetic field of the second permanent magnet, and when the control device energizes the second electromagnet to strengthen the magnetic field of the second permanent magnet, it energizes the first electromagnet to weaken the magnetic field of the first permanent magnet. The clamping mechanism according to claim 1 or 2.

5. The system further includes a control device for controlling the excitation of the first electromagnet and the second electromagnet, When the control device energizes the first electromagnet to strengthen the magnetic field of the first permanent magnet, it does not energize the second electromagnet, and when it energizes the second electromagnet to strengthen the magnetic field of the second permanent magnet, it does not energize the first electromagnet. The clamping mechanism according to claim 1 or 2.

6. The housing is further equipped with a sensor for measuring the force or acceleration applied to it. When the object is held between the fixed clamp claw and the movable clamp claw, and the first electromagnet and the second electromagnet are not energized, if the force or acceleration measured by the sensor exceeds a threshold, the control device energizes the first electromagnet to increase the clamping force that the movable clamp claw applies to the object. The clamping mechanism according to claim 4.

7. The housing is further equipped with a sensor for measuring the force or acceleration applied to it. The control device, when the force or acceleration measured by the sensor is greater than a threshold, continues to energize the first electromagnet that brings the movable clamp claw closer to the fixed clamp claw for the period during which the object should be held. The clamping mechanism according to claim 4.

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