JP4363208B2 - Emergency stop pushbutton switch - Google Patents

Description

  The present invention relates to an improvement of an emergency stop pushbutton switch used in an electric circuit for safe operation of various automatic machines and press devices.

  FIG. 15 shows an example of a conventional emergency stop pushbutton switch. The push button switch B is provided so that the shaft rod g of the push button body f is inserted from the large-diameter cylindrical portion b of the plastic main body case a so as to be able to advance and retreat in the axial direction of the case, and the push button body f is pushed forward. At this position, the elastically deformable locking piece h of the shaft rod g is engaged with a protrusion d provided on the inner side of the small-diameter cylindrical portion c to hold the position, and the push button body f is moved in one direction. , The rear end surface of the locking piece h is disengaged from the projection d, and the push button body f is returned to the original retracted position by the return spring e.

  Inside the large-diameter cylindrical portion b, a pair of movable contacts o provided on the conductive piece n are respectively connected to the fixed contact r by a pressurizing spring t at a position in a normal state where the push button body f is retracted. Provided with a switch portion m configured to be elastically contacted and to move the movable contact o away from the fixed contact r by moving the conductive piece n forward in an emergency stop state where the push button body f is pushed to the forward end. Yes. Further, on the small-diameter cylindrical portion c side, a terminal block j in which a plurality of terminals k inserted into the distal end portion of the fixed terminal piece p extending from the fixed contact r and conducted is provided is detachable.

  The emergency stop push button switch B is used for the purpose of immediately stopping the operation when the operator pushes the push button body f by hand when an emergency occurs during the operation of a machine such as a press device. Is an electrical component. However, when an emergency occurs, the operator may hit the push button body f with a tool such as a hammer or a wrench at hand, so that the push button body f may be damaged or destroyed. For example, as shown in FIG. 16, if the shaft rod g of the push button body f is destroyed due to such a cause, the switch unit m that is instantaneously turned off is turned on again by the elasticity of the pressurizing spring t. (Circuit is closed), so that the emergency stop function is not exhibited.

Incidentally, this type of emergency stop pushbutton switch is defined as an “electrical emergency stop device with a mechanical latch function” in the international standard (IEC60947-5-5). In the item of “Latch” of the content, “If an emergency stop signal is output during operation of the emergency stop device, the emergency stop function shall be maintained by latching the operating system. It shall be maintained until the emergency stop device is reset. The emergency stop device shall not be latched without the output of an emergency stop signal.
JP-A-9-50730 JP-A-5-94732 JP 2002-56735 A JP 2000-123683 A JP 2003-222684 A JP 2003-222688 A

  An object of the present invention is to provide an emergency stop pushbutton switch that can reliably perform an emergency stop operation, has high reliability, and has excellent responsiveness of a switch unit.

In order to achieve the above object, the invention described in claim 1 is provided with a push button body that can be moved forward and backward in the axial direction of the case on a large-diameter cylindrical portion on one end side of a hollow body case. The terminal block with the terminal is detachably attached to the small-diameter cylindrical part on the other end side, and a plurality of movable contacts are accommodated in the large-diameter cylindrical part of the main body case at the original position where the push button body is retracted. A switch part is provided that is elastically contacted by a spring with respect to the fixed contact to be moved, and that allows the movable contact to be separated from the fixed contact while the push button body is pushed in and held at the forward end position. The distal end portion of the fixed terminal piece extending from the contact point is provided so as to be conductive by being pressed against the terminal of the terminal block, and the push button body held at the forward end position is rotated by a predetermined angle so that the push button body is Return position by the return spring In emergency stop pushbutton switch that is configured to return,
Around the shaft portion of the push button body, a stopper protrusion and a locking piece that can be elastically deformed in the radial direction are integrally formed on the outer surface in the axial direction in order from the tip of the cylindrical portion. An inner cylinder having a flange formed at the rear end of the part, and a fixing projection formed on the outer periphery of one end of the cylindrical part, and a claw piece that can be elastically deformed radially at a predetermined position of the cylindrical part An integrally formed outer cylinder is disposed concentrically, and the fixing projection of the outer cylinder is applied to the bottom of the large-diameter cylindrical portion of the main body case and the claw piece is formed in the middle cylinder. The tip of the shaft portion inserted in a notch groove formed in the inner bottom portion with a pushing spring interposed between the shaft portion of the push button body and the inner bottom portion of the middle cylinder Is engaged with a protrusion formed on the inner side of the cylindrical portion of the middle cylinder to provide a detent, In addition, a return spring is interposed between the tip of the shaft portion and the small-diameter cylindrical portion of the main body case, and the protrusion for the stopper of the middle cylinder is made small by the elastic force of the return spring. The push button body is provided so as to be held in the retracted position by being brought into contact with the protrusion formed on the inner side of the part,
When the push button body is pushed in, the claw piece of the outer cylinder is moved outward by the protrusion-shaped cam formed on the outer surface of the shaft portion of the push button body, and the engagement with the outer cylinder is released. By moving the middle cylinder forward by the elastic force of the pushing spring, the middle cylinder temporarily moves over the projection formed on the inside of the small-diameter cylinder of the main body case. And is held at the forward end position together with the push button body, and at the same time, the movable contact provided with the movable contact is pressed by the flange of the middle cylinder and moved backward, thereby moving the movable contact to the above-mentioned position. Provided so that the switch part is turned off by separating from the fixed contact,
On the other hand, by rotating the push button body held at the forward end position by a predetermined angle, the engagement between the locking piece of the middle cylinder and the protrusion of the main body case is released, so that the push button body and the middle cylinder are separated. It is characterized in that it is configured to return to the original retracted position by a return spring.

In order to achieve the above object, the invention described in claim 2 is the emergency stop pushbutton switch according to claim 1, wherein a ring member having a plurality of locking portions formed on the inner diameter side is connected to the rear end of the movable member. The movable member is pressed by the flange of the middle cylinder through the ring member when the push button body is pushed in, and the middle cylinder is moved to the forward end position together with the push button body. When the retaining portion of the ring member is held, it is in a position over the pair of protrusions formed on the inner side of the outer cylinder, and on the other hand, the push button body and the middle cylinder return to the retracted position. In addition, the plurality of movable contacts are simultaneously elastically brought into contact with the fixed contacts by simultaneously engaging the protrusions of the outer cylinder with the engaging portions of the ring member.

  In order to achieve the same object, the invention described in claim 3 is the push button switch for emergency stop according to claim 1 or 2, wherein the push button body is held in the forward end position in the emergency stop state. When damage occurs around the head of the body, the movable contact and the fixed contact are opened by providing a part of the movable member in contact with the protrusion formed on the outer surface of the middle cylinder. The separated OFF state is maintained as it is.

(Invention of Claim 1)
This emergency stop push button switch is configured to move the inner cylinder in conjunction with the push button body forward at once by the elastic force of the pushing spring and to instantaneously separate the movable contact from the fixed contact. The responsiveness to the OFF state of the switch part is good, the emergency stop operation can be performed reliably, and the reliability and safety are excellent.

(Invention of Claim 2)
When the emergency stop push button switch is released, the locking portion of the ring member moves over the protruding portion of the outer cylinder at the same time so that the plurality of movable contacts are simultaneously elastically contacted with the fixed contacts. Since it is configured, the responsiveness to the ON state of the switch unit is very good.

(Invention of Claim 3)
This emergency stop pushbutton switch is excellent in reliability and safety because it is configured to reliably hold the switch portion in the off state even when the periphery of the pushbutton body is damaged.

  The best mode of the present invention will be described below with reference to the drawings. FIG. 1 is a side view of a main part of an emergency stop pushbutton switch in a normal state in which the contact of the switch portion is “closed”, FIG. 2 is an explanatory view showing the arrangement of the contacts in the main body case, and FIG. FIG. 4 is a side view showing a part of the movable member, FIG. 5 is a front view of the push button body, FIG. 6 is a longitudinal side view of the middle cylinder, and FIG. 7 is a plan view of the outer cylinder. FIG. 8 is a longitudinal side view of the outer cylinder, FIG. 9 is a plan view of the ring member, and FIG. 10 is a main part showing a normal state in which the push button body is held at the retracted end position and the contact of the switch portion is “closed”. FIG. 11 is a schematic diagram of a main part showing an emergency stop state in which the push button body is held at the forward end position and the contact of the switch portion is “open”, and FIG. 12 is a schematic view of the push button body held at the forward end position. FIG. 13 is a schematic diagram for explaining the positional relationship between the locking portion of the ring member and the protruding portion of the outer cylinder in a state where the push button body is in the forward end. FIG. 14 is a schematic diagram for explaining the positional relationship between the engaging part of the ring member and the protruding part of the outer cylinder at the moment when the switch part is slightly retracted from the position. FIG. It is a schematic diagram explaining being hold | maintained.

  In FIG. 1, A is an emergency stop pushbutton switch of the present invention. The plastic body case 1 of the pushbutton switch A is formed in a hollow shape, and a plurality of ribs (not shown) are provided at predetermined intervals in the longitudinal direction on the inner surface 2a of the large-diameter cylindrical portion 2 on one end side. A screw 6 is formed on the outer surface of the small-diameter cylindrical portion 5 on the other end side, and a pair of protrusions 7 are integrally formed on the inner surface 5a so as to face each other. As shown in FIG. 10, these protrusions 7 are configured such that the large-diameter cylindrical portion 2 side is an inclined surface 7 a and a top end surface 7 b is provided, and then a back end surface 7 c is provided in a direction orthogonal to the inner surface 5 a. In relation to the stopper projection 38 and the locking piece 39 of the middle cylinder 35, it constitutes a component of the latch mechanism. 8 is a spring receiving member fitted inward of the small-diameter cylindrical portion 5 near the tip, and 9 is a mounting nut screwed into the screw 6 of the small-diameter cylindrical portion 5.

  Inside the large-diameter cylindrical portion 2, a plurality of a pair of left and right fixed terminal pieces 11 each having a fixed contact 13 constituting the switch portion S provided toward the bottom portion 2 b are provided at approximately equiangular intervals at three locations here. While being arranged along the end surface of the rib, the tip of each fixed terminal piece 11 is provided along the inner surface of the small diameter cylindrical portion 5.

  Reference numeral 15 denotes a plastic movable member having a vertically long block shape. As shown in FIGS. 3 and 4, the movable member 15 includes a locking pin 16 on the upper surface 15a, locking portions 17 and 17 protruding on both lower sides of the back surface 15b, and a spring having a certain depth from the lower surface. An insertion hole 18 is provided. At a substantially intermediate position of the movable member 15, a pair of left and right movable contacts 21, 21 fix a conductive plate 20 provided in accordance with the interval between the fixed contacts 13, 13 in a cross shape. As shown in FIG. 2, the movable member 15 is disposed between the pair of fixed terminal pieces 11, 11, i.e., at three locations, and the bottom 2 b of the large-diameter cylindrical portion 2 and the spring insertion hole 18. The plurality of movable contacts 21 are urged in a direction to elastically contact the corresponding fixed contacts 13 by springs 22 interposed therebetween.

  Reference numeral 25 denotes a plastic push button body which is movable back and forth in the axial direction of the main body case 1. As shown in FIG. 5, this push button body 25 is provided so that a shaft portion 27 is integrally formed at the center portion of the umbrella-shaped head portion 26, and the head portion 26 is loosely fitted to the outer surface of the large-diameter cylindrical portion 2. ing. The shaft portion 27 is formed with a ridge-shaped cam 28 in the axial direction at an angular interval of 180 degrees at two locations on the outer surface near the head portion 26, and at the center of the depth from the tip to a substantially intermediate position. A hole 30 is formed. Reference numeral 29 denotes an enlarged diameter portion formed near the tip of the shaft portion 27.

Around the shaft portion 27 of the push button body 25, the middle tube 35 and the outer tube 50 are arranged concentrically around the shaft portion 27.
As shown in FIG. 6, the plastic inner cylinder 35 has a flange 37 formed at one end of a cylindrical portion 36, and a stopper projection 38, which is a component of the latch mechanism, and a latch that can be elastically deformed in the radial direction. The pieces 39 are integrally formed at two positions on the axially outer surface in order from the other end (tip) of the cylindrical portion 36 with an angular interval of 180 degrees. In the cylindrical portion 36, an inner bottom portion 36a is formed near the tip, and arc-shaped notch grooves 40 are formed at two locations on the inner bottom portion 36a. Reference numeral 41 denotes an opening formed at an intermediate position of the cylindrical portion 36, and reference numeral 42 denotes a protrusion formed on the outer surface at the lower edge position of the opening 41.

The push button body 25 is provided with a pushing spring 45 that is set so that a predetermined elastic force is generated between the bottom of the center hole 30 and the inner bottom 36 a of the middle cylinder 36. The shaft portion 27 is detented by engaging the enlarged diameter portion 29 of the shaft portion 27 inserted into the notch groove 40 with a protrusion 39 a formed inside the cylindrical portion 36 of the intermediate cylinder 35. . A return spring 46 is interposed between the enlarged diameter portion 29 and the spring receiving member 8 of the main body case 1.

  As shown in FIG. 10, the push button body 25 makes the rear end surface 38 a of the stopper projection 38 of the middle cylinder 35 abut against the rear end surface 7 c of the projection 7 of the main body case 1 by the elastic force of the return spring 46. It is provided so as to be held at the retracted position in the normal state by contacting.

  As shown in FIGS. 7 and 8, the plastic outer cylinder 50 is formed by forming three fixing projections 52 at equiangular intervals on the outer peripheral surface of the lower end of the cylindrical part 51 and extending upward from the cylindrical part 51. Four rising pieces 53 having a width shape are formed, and protrusions 54 are formed inside the two rising pieces 53 facing each other. Further, a claw piece 55 that is elastically deformable in the radial direction is integrally formed at a substantially intermediate position of the cylindrical portion 51 so as to protrude inward.

  As shown in FIG. 10, the outer cylinder 50 is configured such that the lower surface of the fixing projection 52 is applied to the bottom 2 b of the large-diameter cylindrical portion 2 and the side surface of the projection 52 is between the ribs of the large-diameter cylindrical portion 2. And the tip of the claw piece 55 is provided so as to face the opening 41 of the middle cylinder 35.

  Reference numeral 57 denotes a ring member in which three fitting holes 59 are formed in the ring plate 58 at substantially equal angular intervals. As shown in FIG. 9, on the inner diameter side of the ring plate 58, a locking portion 61 is formed on the inner surface of the annular piece 60 provided at an angular interval of 180 degrees. The ring member 57 is integrally attached to the movable member 15 by fitting fitting holes 59 into the locking pins 16 of the movable member 15.

  As shown in FIG. 11, the movable member 15 is provided so as to be pressed by the flange 37 of the intermediate cylinder 35 via the ring member 57 when the push button body 25 is pushed. Further, as shown in FIG. 12, the locking portion 61 of the ring member 57 gets over the protruding portion 54 of the outer cylinder 50 in a state where the middle cylinder 35 is held at the forward end position together with the push button body 25. On the other hand, when the push button body 25 and the middle cylinder 35 return to the retracted position, the plurality of engaging portions 61 get over the protrusions 54 at the same time, thereby fixing the plurality of movable contacts 21 simultaneously. The contact point 13 is configured to be elastically contacted. The relationship between the protrusion 54 and the locking portion 61 constitutes a latch mechanism.

  Thus, with respect to the switch portion S, the movable contact 21 is elastically contacted with the fixed contact 13 by the spring 22 at the original position in the normal state in which the push button body 25 is retracted (FIGS. 1 and 10). In the emergency stop state where the push button body 25 is pushed to the forward end position, the movable contact 21 is separated from the fixed contact 13 by lowering the movable member 15 by the flange 37 of the middle cylinder 35 as shown in FIG. It is configured to let you.

  Further, the push button body 25 is held at the forward end position when the rear end surface 39b of the locking piece 39 of the middle cylinder 35 shown in FIG. When the push button body 25 is rotated to the right by a certain angle in a state where the push button body 25 is rotated, the locking piece 39 is disengaged from the projection 7 and is returned to the original retracted position by the elastic force of the return spring 46. It has been.

  Reference numeral 70 denotes a plastic terminal block in which a plurality of terminals (not shown) are appropriately arranged. The terminal block 70 is provided so as to be fixed by being inserted into the small diameter cylindrical portion 5 of the main body case 1. In a state where the terminal block 70 is attached to the main body case 1, the distal end portion of the fixed terminal piece 11 of the switch portion S is provided so as to be inserted into a contact piece (not shown) having a spring property. It is a known configuration that can be energized in a pressed state.

  As described above, the emergency stop push button switch A that moves the middle cylinder 35 interlocked with the push button body 25 at a stroke by the elastic force of the push spring 45 itself and momentarily separates the movable contact 21 from the fixed contact 13. Composed.

Next, the operation and operation of the emergency stop push button switch A of the present invention will be described with reference to the drawings.
(1) As shown in FIGS. 1 and 10, the push-button body 25 of the push-button switch A is configured so that the rear end surface 38 a of the stopper projection 38 of the middle cylinder 35 is projected from the protrusion of the main body case 1 by the elastic force of the return spring 46. 7 is held at the retracted position in the normal state. In this normal state, the movable contacts 21 corresponding to the plurality of fixed contacts 13 are in contact with each other by the elastic force of the spring 22, so that the contacts of the switch unit S are in a “closed” state (on state). Retained.
(2) When the push button body 25 is pushed in during an emergency stop, the engagement between the middle cylinder 35 and the outer cylinder 50 is released by pushing the claw piece 55 outward by the cam 28. At this moment, the middle cylinder 35 is moved forward at once by the elastic force of the pushing spring 45 itself, and the locking piece 39 of the middle cylinder 35 gets over the inclined surface 7a of the projection 7 of the main body case 1 and stops. The rear end surface 39a of the piece 39 abuts on the back end surface 7c of the projection 7 (latching action), and the push button body 25 and the middle cylinder 35 are held at the forward end position (FIG. 11).
(3) As shown in FIG. 11, the movable member 15 is pushed down by the flange 37 of the intermediate cylinder 35 via the ring member 57 when the push button body 25 is pushed in. Thereby, since the movable contact 21 is separated from the fixed contact 13, the contact of the switch portion S is in an “open” state (off state). Further, in a state where the middle cylinder 35 is held at the forward end position together with the push button body 25, the locking portion 61 of the ring member 57 has overcome the protrusion 54 of the outer cylinder 50 as shown in FIG. Move forward to position (latch action).
(4) In the emergency stop state held at the forward end position of (3), the locking piece 39 of the middle cylinder 35 is disengaged from the protruding portion 7 of the main body case 1 by rotating the push button body 25 clockwise. Therefore, the push button body 25 and the middle cylinder 35 are returned to the original retracted position by the elastic force of the return spring 46.

(5) When the push button body 25 and the middle cylinder 35 return to the retracted position in (4), the movable member 15 is released from the pressing by the flange 37 of the middle cylinder 35 and the ring member 57 has a plurality of engagements. Since the stop portion 61 climbs over the protrusion 54 of the outer cylinder 50 at the same time, the movable contact 21 is instantaneously brought into contact with the fixed contact 13 by the elastic force of the spring 22, so that the contact of the switch portion S is again “closed”. The state is maintained.

  Incidentally, the response when closing a plurality of contacts in the emergency stop pushbutton switch A of the present invention is 5 (ms), and the performance is remarkably higher than the response of the conventional pushbutton switch: 30 (ms). It was confirmed by experiment that it was high.

  When the pushbutton switch A is in an emergency stop state, as shown in FIG. 14, if the head 26 of the pushbutton body 25 is damaged by being hit with a tool such as a hammer, the protrusion of the middle cylinder 35 When the engaging portion 17 of the movable member 15 is brought into contact with 42, the switch portion S once turned off is not turned on again, and can be reliably maintained in the off state. .

  As described above, this emergency stop pushbutton switch moves the inner cylinder interlocked with the pushbutton body forward at once by the elastic force of the push spring so that the movable contact is instantaneously separated from the fixed contact. Since it comprises, the responsiveness to the OFF state of a switch part is favorable, an emergency stop operation | movement can be performed reliably, and it is excellent in reliability and safety | security. In addition, there is an advantage that the switch portion can be reliably maintained in the OFF state even when the head of the push button body is damaged in the emergency stop state.

Side view of the main part of the push button switch for emergency stop according to the present invention in a normal state in which the contact of the switch part is "closed". Explanatory drawing showing the arrangement of contacts in the body case Plan view of movable member Side view showing a part of the movable member cut away Front view of push button body Longitudinal side view of the middle cylinder Top view of the outer cylinder Longitudinal side view of outer cylinder Plan view of ring member Schematic diagram of the main part showing the normal state where the push button body is held at the retracted end position and the contact of the switch part is "closed" Schematic diagram of the main part showing an emergency stop state in which the push button body is held at the forward end position and the contact of the switch part is "open" The schematic diagram explaining the positional relationship of the latching | locking part of a ring member and the protrusion of an outer cylinder in the state in which the pushbutton body was hold | maintained in the advance end position The schematic diagram explaining the positional relationship of the latching | locking part of a ring member and the protrusion of an outer cylinder in the position of the moment when a pushbutton body retracted a little from the advance end position Schematic diagram explaining that the switch part is held in the OFF state when the head part of the push button body is damaged Vertical side view of a conventional emergency stop pushbutton switch Explanatory drawing of the pushbutton switch for the conventional emergency stop which shows that a switch part will be in an ON state from an OFF state when a shaft rod breaks in the emergency stop state where the pushbutton body was pushed to the advance position

Explanation of symbols

A ... Emergency stop push button switch S ... Switch part 1 ... Main body case 2 ... Large diameter cylinder part 5 ... Small diameter cylinder part
7 ... Projection 11 ... Fixed terminal piece 13 ... Fixed contact 15 ... Movable member 17 ... Locking part 21 ... Movable contact 22 ... Spring 25 ... Push button body 27 ... Shaft part 28 ... Cam 35 ... Medium tube 36 ... Cylinder part 36a ... Inner bottom part 37 ... Flange 38 ... Stopper projection 39 ... Locking piece 39a .. Projection 40: Notch groove 42 ... Projection 45 ... Pushing spring 46 ... Return spring 50 ... Outer cylinder 54 ... Projection 55 ... Claw piece 57 · Ring member 61 ··· Locking portion 70 ··· Terminal block

Claims (3)

A push button body is provided on a large-diameter cylindrical portion on one end side of a hollow main body case so as to be movable forward and backward in the axial direction of the case, and a terminal block on which a plurality of terminals are arranged is a small-diameter cylinder on the other end side. A plurality of movable contacts are elastically contacted by springs to the corresponding fixed contacts at the original position where the push button body is retracted in the large-diameter cylindrical part of the main body case, and the push button body A switch portion is provided that pushes the movable contact away from the fixed contact while being held at the forward end position, and the tip of the fixed terminal piece extending from the fixed contact is used as a terminal of the terminal block. Each of the push button bodies is provided so as to be able to be brought into pressure contact with each other, and further, the push button body held at the forward end position is rotated by a predetermined angle so that the push button body is returned to the original retracted position by the return spring. For pushbutton switch for stop Stomach,
Around the shaft portion of the push button body, a stopper protrusion and a locking piece that can be elastically deformed in the radial direction are integrally formed on the outer surface in the axial direction in order from the tip of the cylindrical portion. An inner cylinder having a flange formed at the rear end of the part, and a fixing projection formed on the outer periphery of one end of the cylindrical part, and a claw piece that can be elastically deformed radially at a predetermined position of the cylindrical part An integrally formed outer cylinder is disposed concentrically, and the fixing projection of the outer cylinder is applied to the bottom of the large-diameter cylindrical portion of the main body case and the claw piece is formed in the middle cylinder. provided so as to face parts, the tip portion of the shaft portion inserted into the notch grooves formed in the inner bottom with interposing the pushing spring between the inner bottom portion in said cylindrical shaft portion of the push button member Is engaged with a protrusion formed on the inner side of the cylindrical portion of the middle cylinder to provide a detent, In addition, a return spring is interposed between the tip of the shaft portion and the small-diameter cylindrical portion of the main body case, and the protrusion for the stopper of the middle cylinder is made small by the elastic force of the return spring. The push button body is provided so as to be held in the retracted position by being brought into contact with the protrusion formed on the inner side of the part,
When the push button body is pushed in, the claw piece of the outer cylinder is moved outward by the protrusion-shaped cam formed on the outer surface of the shaft portion of the push button body, and the engagement with the outer cylinder is released. By moving the middle cylinder forward by the elastic force of the pushing spring, the middle cylinder temporarily moves over the projection formed on the inside of the small-diameter cylinder of the main body case. And is held at the forward end position together with the push button body, and at the same time, the movable member provided with the movable contact is pressed by the flange of the middle cylinder and moved backward, thereby moving the movable contact to the position described above. Provided so that the switch part is turned off by separating from the fixed contact,
On the other hand, by rotating the push button body held at the forward end position by a predetermined angle, the engagement between the locking piece of the middle cylinder and the protrusion of the main body case is released, so that the push button body and the middle cylinder are separated. An emergency stop pushbutton switch configured to return to an original retracted position by a return spring. A ring member having a plurality of locking portions formed on the inner diameter side is fixed to a rear end portion of the movable member, and when the push button body is pushed in, the movable member is interposed by the flange of the middle cylinder via the ring member. The locking portion of the ring member is provided with a pair of protrusions formed on the inner side of the outer cylinder in a state where the middle cylinder is held at the forward end position together with the push button body. When the push button body and the middle cylinder return to the retracted position, the plurality of movable contacts are fixed simultaneously by the ring member's locking part getting over the protruding part of the outer cylinder. 2. The emergency stop push button switch according to claim 1, wherein the push button switch is configured to elastically contact the contact. In the emergency stop state where the push button body is held at the forward end position, if damage occurs around the head of the push button body, a part of the movable member is placed on the protrusion formed on the outer surface of the middle cylinder. 3. The pushbutton switch for emergency stop according to claim 1 or 2, wherein the push-button switch for emergency stop is configured so as to maintain an off state in which the movable contact and the fixed contact are separated by being provided so as to contact each other.

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