Solenoid drive control device and safety switch equipped with same

Abstract

To achieve energy saving to reduce thermal risk due to temperature rise.SOLUTION: A solenoid drive controller 100 is configured to have a solenoid body 22A for attracting a movable iron core 23A and the solenoid body 22A movably supports the movable iron core 23A so that the movable iron core 23A can take a suction position to be sucked by the solenoid body 22A and a non-suction position not to be sucked by the solenoid body 22A. A photo-interrupter 28 for detecting a state of the movable iron core 23A and a current controller 51 are provided. The current controller 51 controls a supply current to the solenoid body 22A according to detection results by the photo-interrupter 28 such that when the movable iron core 23A is at the non-suction position or a position in the vicinity thereof, a drive current Imax is supplied to the solenoid body 22A, and when the movable iron core 23A is at the suction position or a position in the vicinity thereof, a holding current Ih smaller than the drive current Imax is supplied to the solenoid body 22A.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a solenoid drive control device for achieving energy saving and reducing thermal risks due to temperature rise, and a safety switch equipped with the same. [Background technology]

[0002] In general, a solenoid comprises a solenoid body having an electromagnetic coil, and a movable part supported in a slidable manner by the solenoid body. When the electromagnetic coil is energized, a magnetic field is generated from the electromagnetic coil through the movable part, and the movable part is attracted to the solenoid body by the magnetic force.

[0003] Here, since magnetic force is inversely proportional to the square of the distance, in a solenoid, a large current (drive current) is required to attract the moving part, but after the moving part is attracted, the moving part is inside the magnetic field, so an equivalent current is not required and only a small current (holding current) is sufficient.

[0004] However, in conventional solenoids, the same current continues to flow when holding the movable part after attraction as when it was attracted, which increases power consumption, heats up the solenoid and adversely affects surrounding equipment, and if the solenoid is installed in a place where people approach, the heat from the outer cover of the solenoid may cause harm to the human body. Furthermore, there is a risk of the electromagnetic coil burning out.

[0005] In view of this, in the solenoid current control method described in JP 2000-173822 A, when the current switch to the coil is turned on, full current is supplied to the coil, and after a predetermined time has elapsed since the start of current supply, the current to the coil is kept at a small value by a current limiting circuit (see paragraphs

[0046] to

[0048] in the same publication). According to the publication, this configuration reduces the power consumption of the solenoid, reduces the amount of heat generated, and prevents the coil from burning out.

[0006] On the other hand, a safety switch is known as a device using a solenoid. The safety switch is provided at the entrance of a dangerous area where a machine tool or the like is placed, and turns on / off depending on the opening / closing state of the door. The safety switch includes an actuator attached to the door side and a switch body attached to the wall side into which the actuator is inserted and removed. The switch body includes a cam that can be rotated by inserting the actuator, an operating rod that can move in the axial direction and has one end that can abut against the cam and the other end that can switch the contact, and a solenoid disposed around the operating rod. When the movable door is opened or closed, the actuator that moves with the movable door is inserted and removed from the switch body, thereby rotating the cam inside the switch body, and the operating rod moves in the axial direction according to the rotation position, and accordingly the contact is switched on / off, and an on / off signal is sent to the machine tool. The solenoid of the safety switch is provided to switch the cam between lock and unlock by attracting and moving the operating rod when the movable door is opened or closed. Summary of the Invention [Problem to be solved by the invention]

[0007] Conventionally, the current control of the solenoid in such a safety switch has continued to flow the same current as when the operating rod is attracted, even when the attracted state of the operating rod is maintained after the operating rod is attracted, and therefore there have been problems of increased power consumption and thermal risks caused by heat generation in the coil. Therefore, by adopting the method described in the above publication, it is possible to switch from the large current (drive current) at the time of current supply to a small current (holding current) after a certain time has elapsed since current was supplied to the solenoid.

[0008] However, in the case of a safety switch, if the suction action of the operating rod is not completed before the above-mentioned certain time has elapsed, there is a risk of the safety switch failing to lock or unlock. Therefore, it can be said that it is not suitable to control the energization of a solenoid that operates a device such as a safety switch by time.

[0009] The present invention has been made in consideration of the above-mentioned conventional circumstances, and an object of the present invention is to provide a solenoid drive control device that can realize energy saving and reduce the thermal risk caused by temperature rise. Another object of the present invention is to provide a solenoid drive control device that can reliably lock and unlock a safety switch. [Means for solving the problem]

[0010] The present invention is a drive control device for a solenoid, which has a solenoid body for attracting a movable part, and the solenoid body movably supports the movable part so that the movable part can take an attracted position where the movable part is attracted to the solenoid body and a non-attracted position where the movable part is not attracted to the solenoid body. , is the drive current First Current Supplying or , the first current Smaller It is a holding current to hold the moving part. To provide a second current 、 A current control section that controls the current and a current control section that controls the current when a first current is supplied to the solenoid body. 、 moving part is in suction position move What I did and a detection unit for detecting Check By department the law of nature moving part is in suction position move What I have done detection Only after this is done will the current control section The current supplied to the solenoid body is switched from a first current to a second current.

[0011] According to the present invention, the movable part moves to the attracted position when attracted to the solenoid body, and moves to the non-attracted position when not attracted to the solenoid body. At this time, when the first current is supplied to the solenoid body, 、 moving part is in suction position move What I have done Detected by the detector and The current control unit switches the current supplied to the solenoid body from the first current to a second current smaller than the first current, based on the detection of movement of the movable unit by the detection unit.

[0012] As a result, when the movable part is in the attraction position, the current supplied to the solenoid body can be reduced, thereby reducing the current consumption of the solenoid. This not only achieves energy savings through power savings, but also reduces temperature rise and reduces the thermal risk of the coil burning out, etc. Also, in the present invention, the detection section detects that the movable section has moved to a position near the suction position.

[0015] The present invention 、 A safety switch equipped with the drive control device be .

[0016] The safety switch according to the present invention further includes a moving body that moves in response to an action from the movable part. The moving body has an action part that acts on a plurality of contacts for controlling an external device, and a detection part that is provided separately from the action part and is detected by the detection part. Further, a drive control method for a solenoid according to the present invention is a method for moving a movable part to an attraction position and a non-attraction position, and includes the following steps. i) supplying a first drive current, which is a drive current, to the solenoid while the movable part is in the non-attraction position; ii) A step of supplying to the solenoid a second current, which is a holding current for holding the movable part and is smaller than the first driving current, only when the detection unit detects that the movable part has moved from the non-attraction position to the attraction position due to the supply of the first driving current. Effect of the Invention

[0017] As described above, according to the present invention, the movable part is in the suction position. Place At some point, the current supplied to the solenoid body can be reduced to reduce the current consumption of the solenoid, thereby realizing energy savings through power saving and also reducing the temperature rise, thereby reducing the thermal risk of the coil burning out, etc. [Brief description of the drawings]

[0018] [Figure 1] 1 is an exploded assembly view of a switch body of a safety switch to which a solenoid drive control device according to an embodiment of the present invention is applied; [Diagram 2]FIG. 2 is a vertical cross-sectional view of a switch body of a spring-lock type safety switch as an example of the safety switch (FIG. 1). [Diagram 3] FIG. 2 is a perspective view of a contact changeover block (moving body) of the switch body (FIG. 1) viewed from above. [Figure 4] FIG. 4 is a perspective view of the contact changeover block (FIG. 3) viewed from below. [Diagram 5] FIG. 4 is a plan view of the contact switching block (FIG. 3). [Figure 6] FIG. 4 is a front view of the contact switching block (FIG. 3). [Figure 7] FIG. 2 is a schematic block diagram of the drive control device (FIG. 1). [Figure 8] 3 is a time-series diagram showing the operation of the safety switch (FIG. 2) when an actuator is removed. FIG. [Figure 9] 3 is a time-series diagram showing the operation of the safety switch (FIG. 2) when an actuator is removed. FIG. [Figure 10] 3 is a time-series diagram showing the operation of the safety switch (FIG. 2) when an actuator is removed. FIG. [Figure 11] 8 is a graph showing a change in a solenoid current controlled by the drive control device (FIG. 7). [Figure 12] 5 is a time-series diagram showing the operation of a solenoid lock type safety switch, which is another example of the safety switch (FIG. 1), when an actuator is inserted. FIG. [Figure 13] 13 is a time-series diagram showing the operation of the safety switch (FIG. 12) when an actuator is inserted. FIG. [Figure 14] 13 is a time-series diagram showing the operation of the safety switch (FIG. 12) when an actuator is inserted. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] An embodiment of the present invention will now be described with reference to the accompanying drawings. 1 to 11 are diagrams for explaining a solenoid drive control device according to an embodiment of the present invention. Here, an example is taken in which the solenoid drive control device is applied to a spring-lock type safety switch. In addition, in Fig. 2, Fig. 8 to Fig. 10, the cross-sectional areas are shown colored gray. For convenience of explanation, in the following description, "upper", "upper side", and "upper" refer to the upper side in Fig. 2, Fig. 8 to Fig. 10, and "lower", "lower side", and "lower" refer to the lower side in each figure, and depending on how the safety switch is attached, "upper" does not necessarily mean vertically upward, and similarly, "lower" does not necessarily mean vertically downward.

[0020] Fig. 1 is an exploded view of a switch body constituting a safety switch, and Fig. 2 is a view showing a vertical cross section of the switch body together with an actuator. As shown in Figs. 1 and 2, the safety switch 1 includes a switch body 2 and an actuator 3. The switch body 2 includes a body case 20, a main body portion 21 housed in the body case 20 through an opening 20a thereof, a head portion 4 attached to the upper portion of the body case 20 and having a plurality of actuator insertion openings 4a through which the actuator 3 is inserted and removed, and a bottom cover 5 attached to the lower portion of the body case 20. The switch body 2 is attached to, for example, a wall or a fixed door (not shown), and the actuator 3 is attached to, for example, a movable door (not shown).

[0021] As shown in Fig. 1 and Fig. 2, the main body 21 has a solenoid 22, an operating rod 23, and a contact block 24 having a plurality of contacts for controlling an external device, the contacts being switched by the movement of the operating rod 23. As shown in Fig. 2, the solenoid 22 has a solenoid body 22A made of an electromagnetic coil to which a current is supplied from an external power source, a movable iron core (movable part) 23A that is provided so as to be attracted by the solenoid body 22A and is movable in the axial direction so as to take an attracted position attracted to the solenoid body 22 and a non-attracted position not attracted to the solenoid body 22A, and a fixed iron core 22B fixed to the lower part of the solenoid body 22A. The operating rod 23 is disposed inside the movable iron core 23A, passes through the movable iron core 23A vertically, and is acted upon by the movable iron core 23A. The solenoid body 22A is disposed on the outer periphery of the movable iron core 23A. The fixed core 22B has a through hole in the center that supports the operating rod 23 movably in the axial direction, and has an inclined surface 22Ba at the upper end.

[0022] The lower end of the movable core 23A is formed with an inclined surface 23Aa that can come into contact with the inclined surface 22Ba at the upper end of the fixed core 22B. When the movable core 23A moves downward, the inclined surface 23Aa at the lower end of the movable core 23A comes into contact with the inclined surface 22Ba at the upper end of the fixed core 22B, thereby setting a stop end for the downward movement of the movable core 23A, and therefore the fixed core 22B also functions as a stopper for the downward movement of the movable core 23A. In addition, a snap ring (shaft retaining ring) 23C is attached to the outer peripheral surface of the central part of the operating rod 23, and a recess 23Ab that allows the snap ring 23C to move when the operating rod 23 moves is formed on the inner peripheral surface of the lower part of the movable core 23A. When the operating rod 23 moves upward, the snap ring 23C comes into contact with the upper end of the recess 23Ab of the movable iron core 23A, thereby setting a stop end for the upward relative movement of the operating rod 23 with respect to the movable iron core 23A. Note that the movable iron core 23A and the operating rod 23 are arranged to move in the axial direction in conjunction with the axial movement of one of them via the snap ring 23C.

[0023] As shown in FIG. 1, the contact block 24 has a plurality of switchable contacts 24a (only a portion of them is shown in the figure). As shown in FIG. 2, the contact block 24 is engaged with the lower end of the operating rod 23 and is arranged to move together with the operating rod 23, and has a contact switching block (moving body) 25 for switching each of the contacts 24a. The contact switching block 25 has a rib (detected portion) 25A that protrudes to the side (see FIG. 1). As shown in FIG. 1 and FIG. 2, a side plate 26 that faces the rib 25A is disposed on the side of the contact switching block 25. The side plate 26 is provided with a terminal block 27 of the solenoid 22 and a photointerrupter (detection portion) 28 for detecting the rib 25A of the contact switching block 25. The photointerrupter 28 is disposed above the rib 25A in FIG. 2.

[0024] As shown in Fig. 3 to Fig. 6, the contact switching block 25 has a cylindrical portion 25C arranged at the center, a locking recess 25Cb provided at the upper part of the cylindrical portion 25C and capable of locking the lower end of the operating rod 23, and a pair of contact switching portions 25B, 25D protruding on both sides of the cylindrical portion 25C and integrally provided with the cylindrical portion 25C. The lower part of each of the contact switching portions 25B, 25D has inclined surfaces (acting portions) 25B1, 25B2, 25D1, 25D2 acting on each of the contacts 24a of the contact block 24. The above-mentioned rib 25A is provided on one of the contact switching portions 25B. The rib 25A is a thin plate-like member.

[0025] The photointerrupter 28 for detecting the rib 25A is a U-shaped transmissive photosensor in plan view, as shown by the dashed line in Fig. 5, and has a light-emitting section 28A incorporating a light-emitting element, and a light-receiving section 28B incorporating a light-receiving element, which is disposed facing the light-emitting section 28A at a predetermined interval. The light-receiving element of the light-receiving section 28B is configured to receive the light L emitted from the light-emitting element of the light-emitting section 28A, and the rib 25A is detected when the light L between the light-emitting section 28A and the light-receiving section 28B is blocked by the rib 25A as a detection object. Although not shown, the output of the photointerrupter 28 is input to a switching element such as a field effect transistor (FET), for example.

[0026] In this embodiment, the rib 25A is integrally provided with the contact switching block 25, and the contact switching block 25 is engaged with the lower end of the operating rod 23 and moves together with the operating rod 23, so that detection of the rib 25A is equal to detection of the operating rod 23. As described above, the operating rod 23 moves in the axial direction in conjunction with the axial movement of the movable iron core 23A via the snap ring 23C, so that detection of the operating rod 23 is detection of the state of the movable iron core 23A. It can also be said that the contact switching block 25 moves under the action of the movable iron core 23A. For example, an LED (light emitting diode) is used as the light emitting element of the light emitting unit 28A, and for example, a phototransistor is used as the light receiving element of the light receiving unit 28B. When there is no light blocking object, a current flows through the phototransistor, and when there is a light blocking object, no or almost no current flows through the phototransistor, so that the position of the rib 25A and therefore the operating rod 23 (i.e., the position of the movable iron core 23A) is detected by the current change on the light receiving unit 28B side.

[0027] As shown in FIG. 2, a tapered shaft portion 29A of a holder 29, which is disposed below the contact switching block 25 and is attached to the lower portion of the solenoid 22 while holding the contact block 24, is inserted into a hole 25Ca (FIG. 4) formed at the lower end of the cylindrical portion 25C of the contact switching block 25. A compression coil spring 29S is disposed around the shaft portion 29A. The upper end of the compression coil spring 29S is in pressure contact with the bottom wall surface of the hole 25Ca of the cylindrical portion 25C, and the lower end is in pressure contact with the upper surface of the holder 29. With this configuration, the elastic repulsive force of the compression coil spring 29S acts upward on the operating rod 23 via the contact switching block 25.

[0028] As shown in FIG. 2, a cam 40 is provided inside the head portion 4 of the switch body 2, and the cam 40 is rotatably supported on a central shaft 41. A plurality of notches 40c are formed in the cam 40, and the tip of the actuator 3 inserted into the head portion 4 from the actuator insertion port 4a of the head portion 4 engages with the notches 40c of the cam 40 to rotate the cam 40. The movable iron core 23A acts to lock or unlock the rotation of the cam 40 via the operating rod 23, as will be described later. In the state shown in FIG. 2, the tip 23a of the operating rod 23 elastically abuts on a recess 40b formed in the lower part of the cam 40.

[0029] 7 shows a drive control device for the solenoid 22. The drive control device 100 has a photointerrupter 28 and a current control unit 51 that controls the current supplied to the solenoid 22 in accordance with the detection result of the photointerrupter 28, and an external power source 50 is connected to the photointerrupter 28 and the current control unit 51. The current control unit 51 has an analog IC (not shown) that performs two-stage control of the current supplied to the solenoid 22 based on the output from the photointerrupter 28 and also performs constant current control.

[0030] Next, the drive control of the solenoid 22 by the drive control device 100 will be described with reference to FIGS. Fig. 8 corresponds to the state where the movable door is closed. At this time, the actuator 3 attached to the movable door is inserted inside the head portion 4 of the switch body 2 of the safety switch 1, rotating the cam 40 counterclockwise in the figure. Also, no current is supplied from the external power source 50 (Fig. 7) to the solenoid body 22A of the solenoid 22 (solenoid OFF state), and therefore the operating rod 23 and the movable iron core 23A move upward by the action of the elastic repulsive force of the compression coil spring 29S and are disposed at the non-attraction position, whereby the tip portion 23a of the operating rod 23 engages with the notch 40c of the cam 40, and the cam 40 is locked in the rotational direction, thus entering a locked state.

[0031] In this locked state, even if the actuator 3 is to be removed from the head portion 4, the clockwise rotation of the cam 40 is restricted by the interference between the notch 40c and the operating rod 23. Furthermore, the inclined surfaces 25B1, 25B2, 25D1, and 25D2 (FIG. 3) of the contact switching block 25 act on the contacts 24a (FIG. 1) of the contact block 24 to switch the contacts 24a, and an ON signal is output to the machine inside the door, making the machine operable. When the operating rod 23 and the movable iron core 23A are in the non-attraction position, as shown in the partially enlarged view circled in FIG. 8, the rib 25A of the contact switching block 25 shields the light receiving portion 28B of the photointerrupter 28, and the photointerrupter 28 detects the rib 25A. At this time, no or almost no current flows through the light receiving portion 28B of the photointerrupter 28.

[0032] When current is supplied from the external power source 50 to the solenoid 22 via the current control unit 51 (FIG. 7), the solenoid 22 turns ON. At this time, the current control unit 51 supplies a solenoid current to the solenoid body 22A according to the detection result of the photointerrupter 28. This solenoid current is Imax (drive current) as shown in FIG. 11, and the solenoid 22 is driven in full power mode.

[0033] Then, as shown in Fig. 9, the movable iron core 23A is attracted to the solenoid body 22A and moves downward against the elastic repulsive force of the compression coil spring 29S. As a result, the operating rod 23 receives the action from the movable iron core 23A via the snap ring 23C and moves downward. When the inclined surface 23Aa at the lower end of the movable iron core 23A abuts against the inclined surface 22Ba at the upper end of the fixed iron core 22B, the downward movement of the movable iron core 23A and the operating rod 23 stops. The stop position at this time is the attracted position of the operating rod 23 and the movable iron core 23A. At this attracted position, the tip 23a of the operating rod 23 has moved to a position below the bottom surface of the notch 40c of the cam 40. Therefore, the locked state of the cam 40 is released and the cam 40 is in the unlocked state. Also, at this time, as shown in the partially enlarged view surrounded by a circle in Fig. 9, the rib 25A of the contact switching block 25 has moved below the light receiving portion 28B of the photo interrupter 28, and the photo interrupter 28 has not detected the rib 25A, and the light receiving portion 28B is receiving the light from the light emitting portion 28A (Fig. 5). At this time, a current flows through the light receiving portion 28B of the photo interrupter 28.

[0034] Based on the detection result of the photo interrupter 28, as shown in Fig. 11, the current control unit 51 reduces the solenoid current supplied to the solenoid body 22A from Imax to Ih (<Imax) (holding current). Thereby, the solenoid 22 is driven in the energy saving mode. In this embodiment, at an intermediate position between the non-attracted position (Fig. 8) and the attracted position (Fig. 9) of the operating rod 23 and the movable iron core 23A, more specifically, in the vicinity of the attracted position, the photo interrupter 28 is set so as not to detect the rib 25A, that is, it is set so that a current flows through the light receiving portion 28B of the photo interrupter 28. However, the non-detection setting of the rib 25A by the photo interrupter 28 may be performed when the operating rod 23 and the movable iron core 23A reach the attracted position (that is, excluding the vicinity of the attracted position).

[0035] Next, FIG. 10 shows a state in which the actuator 3 has been pulled out from the head portion 4 of the switch body 2 of the safety switch 1 from the state shown in FIG. 9, corresponding to the open state of the movable door. When the actuator 3 is pulled out from the head portion 4, the actuator 3 rotates the cam 40 clockwise as shown in the figure. As a result, the operating rod 23 is pushed downward by the rotating cam 40, and the tip 23a of the operating rod 23 elastically abuts against the concave portion 40b at the lower part of the cam 40. When the operating rod 23 is pushed downward by the cam 40, the operating rod 23 moves downward against the elastic repulsive force of the compression coil spring 29S.

[0036] In FIG. 10, due to the downward movement of the operating rod 23, the rib 25A of the contact switching block 25 also moves downward, and the light receiving portion 28B of the photointerrupter 28 continues to receive light. Therefore, the driving state of the solenoid 22 continues in the energy-saving mode.

[0037] Thus, according to the present embodiment, according to the detection result of the rib 25A by the photointerrupter 28 (that is, the detection of the operating rod 23 (and thus the movable iron core ( 23A)), when the operating rod 23 and the movable iron core 23A are in the non-attracted position, a large solenoid current (driving current) Imax is supplied to the solenoid 22, and when the operating rod 23 and the movable iron core 23A are in the attracted position or a position near thereto, the current control unit 51 controls the current supplied to the solenoid 22 so that a small solenoid current (holding current) Ih (<Imax) is supplied to the solenoid 22.

[0038] Thereby, when the operating rod 23 and the movable iron core 23A are in the attracted position or a position near thereto, the current supplied to the solenoid 22 can be reduced to reduce the consumption current of the solenoid 22. As a result, energy saving due to power saving can be realized, the temperature rise can be reduced, and the thermal risk such as burnout of the coil can be reduced.

[0039] In this embodiment, when transitioning from the cam unlocked state shown in FIG. 9 to the cam locked state shown in FIG. 8, the photointerrupter 28 is set to detect the rib 25A at an intermediate position between when the operating rod 23 and the movable iron core 23A move from the attraction position (FIG. 9) to the non-attraction position (FIG. 8), more specifically, at a position close to the non-attraction position. In other words, the photointerrupter 28 is set so that no or almost no current flows through the light receiving portion 28B of the photointerrupter 28, but the detection of the rib 25A by the photointerrupter 28 may be set at the time when the operating rod 23 and the movable iron core 23A reach the non-attraction position (i.e., not including a position close to the non-attraction position).

[0040] Here, unlike this embodiment, a case will be considered in which the photointerrupter 28 is set to detect that the operating rod 23 and the movable iron core 23A are at the attracted position or a position close thereto during normal operation (i.e., the photointerrupter 28 is set to detect the rib 25A when the operating rod 23 and the movable iron core 23A are at the attracted position or a position close thereto). In this case, when the photointerrupter 28 breaks down (for example, light is no longer emitted from the light-emitting element of the light-emitting part 28A due to deterioration, etc.), even if the operating rod 23 and the movable iron core 23A are at the non-attracted position or a position close thereto, the operating rod 23 and the movable iron core 23A are erroneously detected as being at the attracted position or a position close thereto. Therefore, even in a state in which a drive current must be supplied to the solenoid 22 (a state in which the operating rod 23 and the movable iron core 23A are at the non-attracted position or a position close thereto), no drive current is supplied to the solenoid 22, and a holding current smaller than the drive current is supplied. As a result, the movable iron core 23A is not attracted normally, and the operating rod 23 does not operate normally, causing a locking failure or an unlocking failure.

[0041] In contrast, as in this embodiment, if the photointerrupter 28 is set to detect that the operating rod 23 and the movable iron core 23A are in the non-attracted position or a position close thereto during normal operation, when the photointerrupter 28 breaks down, it will erroneously detect that the operating rod 23 and the movable iron core 23A are in the non-attracted position or a position close thereto (i.e., a state in which a drive current must be supplied to the solenoid) regardless of the actual positions of the operating rod 23 and the movable iron core 23A. Although it is an erroneous detection, since it is always erroneously detected as a "state in which a drive current must be supplied to the solenoid", a drive current is always supplied to the solenoid 22 regardless of the state of the operating rod and the movable iron core 23A. This ensures the basic function of always attracting the movable iron core 23A and operating the operating rod 23 normally, and prevents locking or unlocking failures from occurring.

[0042] Next, Figures 12 to 14 show an example in which the solenoid drive control device according to this embodiment is applied to a solenoid lock type safety switch. In each figure, the same reference numerals as in Figures 8 to 10 indicate the same or corresponding parts, and similarly, cross-sectional areas are colored gray. Also, in the following description, for convenience of explanation, "upper", "upper side", and "top" refer to the upper side in Figures 12 to 14, and "lower", "lower side", and "bottom" refer to the lower side in each figure.

[0043] As shown in Figures 12 to 14, this solenoid lock type safety switch differs from the above-mentioned spring lock type safety switch in that the fixed iron core 22B is disposed above the solenoid 22, the movable iron core 23A is disposed below it, and a coil spring 23S is disposed on the outer periphery of the operating rod 23 between the fixed iron core 22B and the movable iron core 23A. The attraction direction by the solenoid 22 is upward, which is the opposite direction to that of the spring lock type. Also, a snap ring 23C is attached to the outer periphery of the lower part of the operating rod 23.

[0044] 12 shows a state before the actuator 3 is inserted into the head portion 4 of the switch body 2 of the safety switch 1, which corresponds to the open state of the movable door. At this time, the operating rod 23 is pushed downward by the cam 40, and the tip 23a of the operating rod 23 elastically abuts against the recess 40b at the bottom of the cam 40. When the operating rod 23 is pushed downward by the cam 40, the operating rod 23 moves downward against the elastic repulsive force of the compression coil spring 29S. In this state, the cam 40 is in an unlocked state, the movable iron core 23A is not attracted by the solenoid body 22A, and the operating rod 23 and the movable iron core 23A are in the non-attracted position.

[0045] At this time, as shown in the enlarged partial view circled in Figure 12, rib 25A shields light receiving portion 28B of photointerrupter 28, photointerrupter 28 detects rib 25A, and no or almost no current flows through light receiving portion 28B of photointerrupter 28.

[0046] 13 shows a state in which the actuator 3 is inserted into the head portion 4 and the cam 40 is rotated counterclockwise. At this time, the operating rod 23 moves upward due to the action of the elastic repulsive force of the compression coil spring 29S, and the tip 23a of the operating rod 23 is positioned in the notch 40c of the cam 40, and a gap is formed between the tip 23a and the bottom surface of the notch 40c. In addition, the snap ring 23C at the bottom of the operating rod 23 is in pressure contact with the lower end of the movable iron core 23A from below.

[0047] At this time, the cam 40 is in an unlocked state, the movable core 23A is not attracted by the solenoid body 22A, and the operating rod 23 and the movable core 23A are in the non-attracted position. Also, at this time, as shown in the partially enlarged view circled in Fig. 13, the rib 25A still shields the light receiving portion 28B of the photointerrupter 28, the photointerrupter 28 detects the rib 25A, and no or almost no current flows through the light receiving portion 28B of the photointerrupter 28.

[0048] When current is supplied from the external power source 50 to the solenoid 22 via the current control unit 51 (FIG. 7), the solenoid 22 turns ON. At this time, the current control unit 51 supplies a solenoid current to the solenoid body 22A according to the detection result of the photointerrupter 28. This solenoid current is Imax (drive current) as shown in FIG. 11, and the solenoid 22 is driven in full power mode.

[0049] Then, as shown in Fig. 14, the movable iron core 23A is attracted by the solenoid body 22A and moves upward against the elastic repulsive force of the coil spring 23S, so that the operating rod 23 moves upward together with the movable iron core 23A. Then, when the inclined surface 23Aa at the upper end of the movable iron core 23A abuts against the inclined surface 22Ba at the lower end of the fixed iron core 22B, the upward movement of the movable iron core 23A and the operating rod 23 stops. The stop position at this time is the attracted position of the operating rod 23 and the movable iron core 23A. At this attracted position, the tip 23a of the operating rod 23 is located at a position abutting or approaching the bottom surface of the notch 40c of the cam 40, so that the cam 40 is in a locked state. At this time, as shown in the partially enlarged view circled in Fig. 14, the rib 25A of the contact switching block 25 has moved above the light receiving portion 28B of the photointerrupter 28, the photointerrupter 28 is not detecting the rib 25A, and the light receiving portion 28B is receiving light from the light emitting portion 28A (Fig. 5). At this time, a current flows through the light receiving portion 28B of the photointerrupter 28.

[0050] Based on the detection result of the photointerrupter 28, as shown in FIG. 11, the current control unit 51 reduces the solenoid current supplied to the solenoid body 22A from Imax (drive current) to Ih (<Imax) (holding current). Thereby, the solenoid 22 is driven in the energy-saving mode. In this embodiment, more specifically, in the intermediate position until the operating rod 23 and the movable iron core 23A move from the non-attraction position (FIG. 13) to the attraction position (FIG. 14), that is, in the vicinity of the attraction position, the photointerrupter 28 is set so as not to detect the rib 25A. That is, it is set so that current flows through the light-receiving portion 28B of the photointerrupter 28. However, the setting of non-detection of the rib 25A by the photointerrupter 28 may be performed when the operating rod 23 and the movable iron core 23A reach the attraction position (that is, excluding the vicinity of the attraction position).

[0051] Thus, according to this embodiment, in accordance with the detection result of the rib 25A by the photointerrupter 28 (that is, the detection of the operating rod 23 (and thus the movable iron core 23A)), when the operating rod 23 and the movable iron core 23A are in the non-attraction position, a large solenoid current (drive current) Imax is supplied to the solenoid 22, and when the operating rod 23 and the movable iron core 23A are in the attraction position or its vicinity, the current control unit 51 controls the current supplied to the solenoid 22 so that a small solenoid current (holding current) Ih (<Imax) is supplied to the solenoid 22.

[0052] Thereby, when the operating rod 23 and the movable iron core 23A are in the attraction position or its vicinity, the current supplied to the solenoid 22 can be reduced to reduce the power consumption of the solenoid 22. As a result, energy saving due to power saving can be realized, the temperature rise can be reduced, and the thermal risk such as burnout of the coil can be reduced.

[0053] In this example as well, when transitioning from the cam locked state shown in FIG. 14 to the cam unlocked state shown in FIG. 13, the photointerrupter 28 is set to detect the rib 25A at an intermediate position between when the operating rod 23 and the movable iron core 23A move from the attraction position (FIG. 14) to the non-attraction position (FIG. 13), more specifically, at a position close to the non-attraction position. In other words, the photointerrupter 28 is set so that no or almost no current flows through the light receiving portion 28B of the photointerrupter 28, but the detection of the rib 25A by the photointerrupter 28 may be set at the point when the operating rod 23 and the movable iron core 23A reach the non-attraction position (i.e., not including a position close to the non-attraction position).

[0054] Here, unlike this embodiment, a case will be considered in which the photointerrupter 28 is set to detect that the operating rod 23 and the movable iron core 23A are at the attracted position or a position close thereto during normal operation (i.e., the photointerrupter 28 is set to detect the rib 25A when the operating rod 23 and the movable iron core 23A are at the attracted position or a position close thereto). In this case, when the photointerrupter 28 breaks down (for example, light is no longer emitted from the light-emitting element of the light-emitting part 28A due to deterioration, etc.), even if the operating rod 23 and the movable iron core 23A are at the non-attracted position or a position close thereto, the operating rod 23 and the movable iron core 23A are erroneously detected as being at the attracted position or a position close thereto. Therefore, even in a state in which a drive current must be supplied to the solenoid 22 (a state in which the operating rod 23 and the movable iron core 23A are at the non-attracted position or a position close thereto), no drive current is supplied to the solenoid 22, and a holding current smaller than the drive current is supplied. As a result, the movable iron core 23A is not attracted normally, and the operating rod 23 does not operate normally, causing a locking failure or an unlocking failure.

[0055] In contrast, as in this embodiment, if the photointerrupter 28 is set to detect that the operating rod 23 and the movable iron core 23A are in the non-attracted position or a position close thereto during normal operation, when the photointerrupter 28 breaks down, it will erroneously detect that the operating rod 23 and the movable iron core 23A are in the non-attracted position or a position close thereto (i.e., a state in which a drive current must be supplied to the solenoid) regardless of the actual positions of the operating rod 23 and the movable iron core 23A. Although it is an erroneous detection, since it is always erroneously detected as a "state in which a drive current must be supplied to the solenoid", a drive current is always supplied to the solenoid 22 regardless of the state of the operating rod and the movable iron core 23A. This ensures the basic function of always attracting the movable iron core 23A and operating the operating rod 23 normally, and prevents locking or unlocking failures from occurring.

[0056] [First Modification] In the above embodiment, the contact switching block 25 has both the function of switching the contacts 24a of the contact block 24 and the function of detecting the position of the operating rod 23, thereby making it easy to link the two functions and reducing the number of parts to reduce manufacturing costs, but the application of the present invention is not limited to this. A detection target may be directly attached to the operating rod 23, and the photointerrupter 28 may detect this detection target.

[0057] [Second Modification] In the above embodiment, the photointerrupter 28 is used as a detection unit for detecting the rib 25A of the contact switching block 25. However, instead of the photointerrupter 28, a reed switch, a microswitch, a magnetic switch, or the like may be used.

[0058] [Third Modification] In the above embodiment, the current supplied to the solenoid 22 is controlled by two-stage control and constant current control using an analog IC. OdeAlthough an example of controlling the solenoid 22 has been shown, the application of the present invention is not limited to this. For example, pulse control may be performed. That is, a pulse voltage may be applied to the solenoid 22 and the duty cycle of the pulse width may be changed to control the current supplied to the solenoid 22. Alternatively, the current supplied to the solenoid 22 may be controlled by lowering the input voltage using a dropper circuit.

[0059] [Fourth Modification] In the above embodiment, an example is shown in which the operating rod 23 is provided in addition to the movable iron core 23A, but the application of the present invention is not limited to this. In the present invention, the operating rod 23 may be omitted and the movable iron core 23A may be extended in the axial direction so that the movable iron core 23A also functions as the operating rod. In this case, the state of the movable iron core 23A can be directly detected by the photointerrupter 28.

[0060] [Fifth Modification] In the above embodiment, the photointerrupter 28 detects via the operating rod 23 that the movable core 23A is at the non-attraction position or a position nearby, but the application of the present invention is not limited to this. The photointerrupter 28 in the present invention may detect via the operating rod 23 that the movable core 23A is at the attraction position or a position nearby.

[0061] [Sixth Modification] In the above embodiment, the operating rod 23 also functions as a locking member that locks the cam 40, but the application of the present invention is not limited to this. In the present invention, the locking member that locks the cam 40 may be provided separately from the operating rod 23.

[0062] [Seventh Modification] In the above embodiment, the solenoid applied to the spring lock type safety switch corresponds to the so-called "pull type", and the solenoid applied to the solenoid lock type safety switch corresponds to the so-called "push type", but the solenoid to which the drive control device of the present invention is applied can be similarly applied to the so-called "self-holding type" that holds the movable iron core at the attraction position by utilizing the attractive force of a permanent magnet. In this case, the holding current of the solenoid is zero (i.e. Ih = 0).

[0063] [Eighth Modification] In the above embodiment, an example has been shown in which the state of movable core 23A (i.e., whether it is in the attracted position or the non-attracted position) is indirectly detected by detecting the position of operating rod 23, but the member used for position detection is not limited to operating rod 23. Any movable member may be used as long as it is linked to movable core 23A.

[0064] [Ninth Modification] In the above embodiment, a solenoid in which the movable core 23A reciprocates in the axial direction (i.e., moves linearly) has been described as an example, but the present invention can be similarly applied to solenoids in which the movable core tilts (or rotates) around a fulcrum, rotates around an axis, etc. In this way, the drive control device according to the present invention can be applied to all electrical components that attract a movable core by passing a current through a copper wire to generate a magnetic field.

[0065] [Other Modifications] The above-described embodiments and modifications should be considered in all respects as merely illustrative of the present invention, and not restrictive. Those skilled in the art to which the present invention pertains may, in consideration of the above teachings, construct various modifications and other embodiments that incorporate the principles of the present invention without departing from the spirit and essential characteristics of the present invention, even if not expressly described herein.

[0066] [Other application examples] The present invention is not limited to the above-mentioned safety switch, but can be applied to various devices and apparatuses that use solenoids. [Industrial Applicability]

[0067] INDUSTRIAL APPLICABILITY The present invention is useful for a solenoid drive control device that realizes energy saving and reduces thermal risks due to temperature rise. [Explanation of symbols]

[0068] 1: Safety switch 2: Switch body 3: Actuator 40: Cam 22: Solenoid 22A: Solenoid body 23A: Movable core (moving part) 25: Contact changeover block (moving body) 25A: Rib (detection part) 25B1, 25B2, 25D1, 25D2: Slanted surface (action part) 28: Photointerrupter (detection part) 51: Current control section 100: Drive control device Imax: Drive current (first current) Ih: Holding current (second current) [Prior art documents] [Patent documents]

[0069] [Patent Document 1] JP 2000-173822 A (see paragraphs

[0046] to

[0048] )

Claims

1. A drive control device for a solenoid having a solenoid body for attracting a movable part, the solenoid body movably supporting the movable part so that the movable part can take an attracted position where it is attracted to the solenoid body and a non-attracted position where it is not attracted to the solenoid body, a current control unit that performs current control so as to supply a first current, which is a drive current, to the solenoid body, or a second current, which is a holding current for holding the movable part and is smaller than the first current, to the solenoid body; a detection unit that detects that the movable unit has moved to the attraction position when the first current is supplied to the solenoid body, The current control unit switches the current supplied to the solenoid body from the first current to the second current only when the detection unit detects that the movable unit has moved to the attraction position. A solenoid drive control device comprising:

2. In claim 1, The detection unit detects that the movable unit has moved to a position near the suction position. A solenoid drive control device comprising:

3. A safety switch equipped with a drive control device for a solenoid as described in claim 1.

4. In claim 3, A moving body that moves in response to the action of the movable part is further provided, The moving body has an acting portion that acts on a plurality of contacts for controlling an external device, and a detection portion that is provided separately from the acting portion and is detected by the detection portion. A safety switch characterized by:

5. A method for controlling a solenoid to move a movable part to an attraction position and a non-attraction position, comprising: supplying a first drive current, which is a drive current, to the solenoid while the movable portion is in the non-attraction position; a second current, which is a holding current for holding the movable part and is smaller than the first driving current, is supplied to the solenoid only when a detection unit detects that the movable part has moved from the non-attraction position to the attraction position by the supply of the first driving current; A method for controlling the drive of a solenoid.

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