Tripping emergency push-button

Abstract: Tripping emergency push-button comprising a first or a second movable knob (12, 13) acting on an obstacle clearing mechanism, operating by rotation around an axis parallel to the movement direction of said movable slider (12, 13), comprising a slidable member (32), provided with at least a retaining tooth (48), which at the lowering of said first or second movable knob (12, 13) rotates around its axis parallel to the moving direction of one of the knobs (12, 13) compelling said at least one retaining tooth (48) to clear an obstacle (58) and, once the slidable member (32) has cleared through tripping action said obstacle (58), it also rotates in a tripping way carrying said retaining tooth (48) under said obstacle (58), preventing so the coming back of said slidable member (32) in said raised position. The release of the at least one retaining tooth (48) can happen just through a rotating movement, in a reversed direction with respect to the retaining movement, provided by rotation of a first of said knobs (12) or of a cylinder lock (15) within a second of said knobs (13).

Description: The present invention refers to an emergency push- button comprising the features of the preamble of claim 1 (see GB-A-2 169 142). Such emergency push-buttons have safe and non equivocal actuation, obtained through tripping, of the kind used for providing safety interventions on electrical, electromechanical or electronic devices or plants in order to obviate problems or to intervent the fastest the possible in emergency situations. Such emergency push-buttons are largely used for example, but not exlusively, on carrying or lifting devices, such as conveying belts, elevators, cranes, escalators and lifts, or in monitoring and alert plants against accidents, such as fires, blastings, floods, or crimes, such as stealings, hooliganisms, damages or the like. There are already many emergency push-buttons and one of the objects sought to be obtained therethrough is a safe actuation, i. e. the safety that, once they are actuated, not only they interrupt their action or are deactuated, but can be deactuated only at will by an explicit deactuating action. Further, said emergency push-buttons, must operate switches actuated by them even in case of failures of their components or damages to the contacts, such as light welding thereof. All the emergency push-buttons, to meet the safety international regulations, are provided with a large knob or slider, having mushroom shape, which is actuable by a hand palm to permit the fastest and the safest the possible intervention. A known kind of emergency push-button uses on a stem of said mushroom knob a permanent magnet secured thereto which, being depressed by action on the knob, is coupled to another permanent magnet strictly connected to fixed structures of the same emergency push-button and inversly biased with respect to the first magnet, so that the above magnets sharply attract each other, when their reciprocal distance falls under a preset level, providing the knob collapse without any actuation unsafety. In this case the actuation is very safe, but there is however a problem of a very difficult push-button deactuation if the two permanent magnets come too near each other, owing to the very high forces required to disconnect them. It is possible to try to reduce said force to a reasonable level by interposing a non magnetic material gap, having calibrated thickness, but any event squeezing, detaching or however thinning such a gap can result again in exaggerated attractive forces between the magnets, making void all the advantages coming from said non magnetic gap. Another known kind of emergency push-button is a snap action push-button providing on a stem of the mushroom knob two conical enlargements having bases facing each other separated by a circumferential groove of semicircular cross-section to house latches or engaging means, such as balls, provided around said stem and pushed by springs acting perpendicularly to the axis of said stem and arranged in seats dug in a fixed housing of said push-button, said latches or balls acting as latching means to maintain the emergency push-button in actuated position when an actuation has been carried out thereon. This second system is however more unsafe than the first one, because it is sufficient that the knob actuation is a little weaker than necessary for having the knob coming back in the deactuated position as the latches or the balls were not able to go over the tripping point in going from the conical surface to the circumferential groove. Further, wear in the edges of the groove makes actuation more and more unsafe, eventually lowering the reliability of the push-button. GB-A-2 169 142 discloses an improvement with respect to the above mentioned snap action push-button provided with latches in the form of plungers urged by springs in a direction perpendicular to the axis of the push-button, the latches, because of a push on the push-button, clearing corresponding projections in the steady body of the push-button itself and remaining engaged under the projections themselves. The disengaging of the latches from the projections is provided by rotation of the push-button itself engaging the external ends of the plungers against cam surfaces gradually withdrawing the plungers until the projections are cleared. Of course this kind of disengagement by rotation of the push-button reduces the wearing of the latches, but cannot eliminate it completely because the plungers of the latches have to move into recesses in the stem of the push-button and scrape against the cam surfaces during the disengagement remaining prone to wearing due to both friction of the plungers in their recesses and friction of their tips against the projections of the steady body at the engagement thereof and against the cam surfaces at their disengagement. The problem of this snap action push-button is a reduced life connected with the above mentioned remaining wears. An object of the present invention is to provide an emergency push-button having active contact opening preserving switching features in the time in spite of possible wear of components without having difficult recovery or unsafe actuation. A further object is to provide through a suitable overstroke of movable components of said push-button an active actuation of controlled contacts even in the case of faults of push-button components or contact damages, such as a light welding. It is to realize that the prior art emergency push-buttons hereabove considered are all of the direct action and latching kind, in which a force applied to contact means, such as microswitches or the like, directly depends on the force normally applied to their knobs. On the contrary, an emergency tripping push-button would be suitable in which the energy provided to actuate contacts is properly stored in spring means remaining always the same and providing a constant actuating power. The above object is attained by an emergency push-button with a safe actuation, comprising a fixed housing, a knob movable along an axis thereof upon actuation of the knob, retaining and releasing means positioned in said housing for said axially movable knob, a slider support rigidly connected to said knob and spring-biased in said housing, said retaining and releasing means including a member suited to rotate around an axis parallel to a direction of actuation of said knob and movable in an axial direction of said knob by axial sliding of said slider support, after said knob has been actuated, characterized by said retaining and releasing means further including a plurality of retaining members provided on said movable member and a plurality of protrusions provided on said housing, said retaining members cooperating with said protrusions, as said movable member rotates, so that said retaining members move in a direction of rotation of said movable member and subsequentely abut under the respective protrusions, said retaining members clearing said protrusions through a subsequent rotation of said movable member and a movement of said retaining members around said protrusions, and by means effecting a rotational movement of said movable member, before said movable member is axially moved, said movable member including a stem extending into said slider support, said means effecting rotational movement including a cam assembly formed within said stem and a pin provided in said slider support and movable therealong and extending transversely of said axis, said pin being engaged in and cooperating with said cam assembly to cause rotation and a tripping action of said movable member resulting in engagement of said retaining members with or disengagement of said retaining members from said protrusions, respectively. In a preferred embodiment said cam assembly includes a recess formed in said stem, said recess being provided with at least two shaped surfaces of which one surface is parallel to said axis of the knob and antoher surface is sloping with respect to said axis. Preferably, said recess is provided with two pairs of opposing shaped surfaces, of which a first pair is positioned parallel to the axis of movement of the knob and a second pair has surfaces sloping with respect to said axis. More preferably, said movable member is connected to said knob by resilient means which are loaded in a first direction parallel to the axis of said knob and in a second direction perpendicular to said axis of said knob to allow a) a first rotary movement of said movable member in order to permit said retaining members of the movable member to snap on said protrusions, as said retaining members move around said protrusions, or to clear said protrusions, b) an axial advancing movement of said retaining members beyond said protrusions, and c) a second rotary movement in a direction opposite to that of said first rotary movement to ensure engagement of said retaining members of said movable member with said protrusions. Still more preferably, retaining members are retaining teeth. Particularly, said resilient means comprise a first axially extending spring acting on said slider support and which is charged through compression to allow advancing of said movable member with respect to said protrusions, and a second spring acting on said movable member to move around said protrusions and then is discharged to carry said retaining teeth under said protrusions. Alternatively said resilient means comprise just one spring acting on said movable member and strainable in an axial direction by compression and in a rotary direction by torsion in order to allow said retaining teeth to move around said protrusions to axially advance said teeth beyond said protrusions and to move said retaining teeth back under said protrusions. According to another alternative, said resilient means comprise at least one elastomeric sleeve acting on said movable member and strainable by compression and by rotation in order to force said retaining teeth to move around said protrusions to axially advance said teeth and to move said teeth back under said protrusions. In addition, the emergency push-button of an embodiment of the invention is characterized in that said movable member has a planar disk at a lower end thereof and that said cam assembly has an axial length smaller than a stroke permitted to said movable knob so that in case of breaking of said resilient means a deeper stroke of said movable knob into said housing is always ensuring the movement thereof, even if a movement of said planar disk is hindered by damages to controlled means. Preferably, said resilient means comprise a pair of springs of which one operates by an axial movement of said knob and another operates by rotation of said knob. More preferably, said resilient means comprise just one spring constructed to be strainable by axial compression due to actuation of the push-button, to remain compressed by engagement of said retaining teeth under said protrusions and to be subsequentely strained by torsion caused by a rotation of said knob to release said retaining teeth from said protrusions. In particular, said means is constructed to remain charged after said knob has been held lowered by said movable member which in turn has been held by said retaining teeth under said protrusions, said resilient means being further actuable by rotation of said knob in order to release said retaining teeth from said protrusions and to bring said knob back to a rest position thereof. In addtion the emergency push-button of an embodiment of the present invention further comprises a cylinder lock connected to said slider support and suited to place the push-button to a recovered position after actuation, said lock being turnable by a key. The features and advantages of embodiments of the present invention will be more apparent from the following detailed description, not to be considered in limiting sense, provided with the enclosed drawings, in which: figure 1 is a side view, in cross section, of a first embodiment of the invention; figure 2 is a lateral view, in cross section, of a second embodiment of the invention, differing from the first embodiment by a key recovery mechanism; figure 3 is a perspective, partially broken away view of a cam mechanism used in both embodiments; figure 4 is a cross section view along line A-A of either figure 1 or figure 2; figure 5 is a cross section view along line B-B of either figure 1 or figure 2; figure 6 is a cross section view along line C-C of figure 1; figure 7 is a cross section view along line D-D of figure 2. Referring now to figures 1 and 3, depicting a first embodiment, an emergency push-button 10 consists of a movable slider 12, having the shape of a mushroom knob, slidable in a substantially tubular housing 14 in which it is sealed by a seal 16. The mushroom knob 12 is connected through a pin 18 to a plastic support 20 spring held in an emitted position by a spring 22 abutting against a flange 23 of said support 20 and against a seat 24, comprised in the tubular housing 14, said spring having the duty to maintain the mush room knob 12 in emitted position. Through the plastic support 20 passes a second pin 26 engaged in a cam assembly 28 within a stem 30 of a movable member 32 transmitting, through a planar disk pad 34, an axial movement to underlying contact means (not shown in figure 1). The above mentioned plastic support 20 is provided with a bore 36 housing the stem 30 of the movable member 32 and ends with a seat 38 housing a spring 40 abutting on a shoulder 42 of the underlying movable member 32, said spring 40 being further secured by a first pin 44 extending into a hole through the seat 38 and by a second pin 46 extending into a hole through the shoulder 42. The movable member 32 is provided with a plurality of small retaining teeth 48 and of stroke limiting teeth 50. The planar disk pad 34 abuts eventually in the rest position against a seat 52 formed in the lower end 54 of the tubular housing 14. The lower end 54 of the housing 14 is provided with an internal bore 56 from which extend protrusions 58, engageable with the retaining teeth 48. Referring now particularly to figures 3 and 4, the structure of the cam assembly 28 is better understood. The cam assembly 28 has a bore housing the pin 26 and crossing the stem 30, provided with two first opposing profiles 60 and 62 sloping with respect to the axis of the stem 30 and with two second opposing profiles 61 and 63 parallel to said axis and joining said two profiles 60 and 62 along a rounded corner 65. Figure 2 depicts a second embodiment of the invention similar to the first one, except that instead of the mush-room knob 12 is used a mushroom knob 13, provided with a cylinder lock 15 actuable to recovery the knob 13 by means of a key 17, connected to the support 20 through a pin 18 and provided with a seal 19, the remaining components of said second embodiment being substantially similar to those of said first embodiment. To understand the operation of the two embodiments, reference is made to figures 1 to 5. When either the mushroom knob 12 or the mushroom knob 13 is depressed, the plastic support 20 is depressed too, trailing the pin 26 in axial downwards movement. The pin 26 acts against the two sloping opposed profiles 60 and 62 of the cam assembly 28, causing the rotation of the stem 30 connected to the movable member 32, compelling the spring 40, connected to respective pins 44 and 46 to the support 20 and to the movable member 32, to be charged both by compression and by torsion. The rotation of the movable member 32 moves the retaining teeth 48 from an abutting position on underlying protrusions 50 to void areas 64 (see Fig.5) allowing said teeth 48 to come under the protrusions 58. Once the retaining teeth 48 crossed the void areas 64, the movable member 32, pushed by the spring 40 is snap-lowered by a tripping action and the torsion provided to the spring 40 carried the retaining teeth 48 under the protrusions 58, always through a tripping action, i.e. discharging the spring 40, returning the lowered position of said movable slider 32 and consequently, acting definitely on the contact means controlled thereby. The rotation of the movable member 32 cannot be larger than that allowed by the extension of the free areas 64, because of two limiting teeth 50 movable within limited slots 66, said rotation being also limited in reversed direction, when the retaining teeth 48, after, coming come into the free areas 64, move to lie under the protrusions 58. In summary, an actuation of the mushroom knob 12 or 13 compels the movable member 32 to rotate around its axis in a first time in clockwise direction to disengage the theeth 48 from the protrusions 58 and then, once said movable member 32 has been lowered , to carry said retaining teeth 48, by means of a rotation in counterclockwise direction under the protrusions 58, providing to engage the movable member 32 in lowered position. It is to realize that the profiles 61 and 63 are preferably manufactured parallel to the axis of the stem 30 of the cam assembly 28, with a legnth quite lesser than the stroke lenght of the movable knobs 12 or 13, so that in case of breaking of the spring 40 said further stroke permitted to the movable members, allows to transmitt a push of the member, through abutting of the pin 26 against the rounded corner 65, ever advancing the movable member 32, permitting also in such a case the operation of the planar disk pad 34 on the underlying contact means. Further, should the contacts of the underlying means be somehow hindered, such as by partial welding, the supplementary push of the pin 26 against the corner 65 can help in separating said contacts. The two embodiments of the present invention have also clearing means and mechanisms allowing to carry the push button to a rest position, after it has been actuated, when the emergency situation has been overcome, or however when the alerting signals connected to said situations are no longer useful. The recovering mechanisms are of two kinds chiefly depicted in the respective figures 1 and 2, 6 and 7. To recover the emergency push-button which, once pressed, maintains actuated the controlled contact means , it needs to return to the rest position the movable member 32, by disengaging the retaining teeth 48 from the protrusions 58 in the internal bore 56 of the lower portion 54 of the tubolar housing 14. To this purpose, according to the first embodiment, it needs to rotate the mushroom knob 12, for example in clockwise direction, to trail , through the pin 26 and the stem 30, the movable member 32, disengaging the retaining teeth 48 from their position under the protrusion 58 to the position in front of the free areas 64. In making such a rotation, the spring 22, which was compressed, undergoes also a torsion owing to end pins 70 and 72 respectively coupled to the support 20 and to the seat 24 of the tubular housing 14. The retaining teeth 48, going under the free areas 64, are lifted by the spring 22 allowing the movable member 32 to come back in the rest position of figure 1. The spring 22, which was torsion charged because of the rotation of the mush room knob 12, is now discharged returning the teeth 48 on the protrusions 58, thus preventing an unwanted falling down of the movable member 32. The rotation of the mushroom knob 12 is possible because, as depicted in figures 4 and 6, the tubular housing 14 is internally provided with two axial ribs 74 and 76 engaging two enlarged grooves 78 and 80 externally provided in the stem of the mushroom knob 12. In fact, when by grasping the mush-room knob 12 it is rotated in the clockwise direction, the enlarged grooves 78 and 80 formed in the stem of the knob 12 permit the rotation, providing then through the action of the pins 18 and 26, the clearing of the retaining teeth 48 from the protrusions 58, the lifting of the teeth 48 through the free areas 64 by release of the spring 22, which was axially compressed, and the coming back of the teeth 48 over the protrusions 58, by discharging of the torsion of said spring 22 undergone during the recovery rotation of the mushroom knob 12. According to another embodiment , the recovery is provided through rotation of a cylinder lock 15 by a key 17. In this case the mushroom knob 13 cannot rotate with respect to the tubular housing 14, becuase as depicted in figure 7, the stem is provided with grooves 82 and 84 substantially following in size the ribs 74 and 76 inside the tubular housing 14. However, since the cylinder lock 15 is turnable with respect to the mushroom knob 13 and the lock is connected to the support 20 through the pin 18, the recovery rotation of the support 20 and the consequent torsion of the spring 22 are secured by said cylinder lock 15, which of course, can be turned just when the key 17 is inserted in the lock 15. The rotation of the cylinder lock 15 allows a recovery of the movable member 32 in a way completely similar to that of the movable member 32 of figure 1 embodiment. What has been hereabove specified depictes two not limiting embodiments of the present invention. The springs 22 and 40 provided with pins assuring their torsion, could be replaced with two respective springs, separately assuring axial and rotating movements, or said springs could be replaced by sleeves of elastomeric materials, provided with pin fasteners, or the like, to allow said axial and rotating movements.

Claims: Emergency push-button with a safe actuation, comprising a fixed housing (14), a knob (12, 13) movable along an axis thereof upon actuation of the knob (12, 13), retaining and releasing means positioned in said housing (14) for said axially movable knob (12, 13), a slider support (20) rigidly connected to said knob (12, 13) and spring-biased in said housing (14), said retaining and releasing means including a member (32) suited to rotate around an axis parallel to a direction of actuation of said knob (12, 13) and movable in an axial direction of said knob by axial sliding of said slider support (20), after said knob (12, 13) has been actuated, characterized by said retaining and releasing means further including a plurality of retaining members (48) provided on said movable member (32) and a plurality of protrusions (58) provided on said housing (14), said retaining members (48) cooperating with said protrusions (58), as said movable member (32) rotates, so that said retaining members (48) move in a direction of rotation of said movable member (32) and subsequentely abut under the respective protrusions (58), said retaining members (48) clearing said protrusions (58) through a subsequent rotation of said movable member (32) and a movement of said retaining members (48) around said protrusions (58); and by means effecting a rotational movement of said movable member (32) before said movable member (32) is axially moved, said movable member (32) including a stem (30) extending into said slider support (20), said means effecting rotational movement including a cam assembly (28) formed within said stem (30) and a pin (26) provided in said slider support (20) and movable therewith and extending transversely of said axis, said pin (26) being engaged in and cooperating with said cam assembly (28) to cause rotation and a tripping action of said movable member (32) resulting in engagement of said retaining members (48) with or disengagement of said retaining members (48) from said protrusions (58), respectively. The emergency push-button according to claim 1, characterized in that said cam assembly (28) includes a recess formed in said stem (30), said recess being provided with at least two shaped surfaces (60, 61) of which one surface (61) is parallel to said axis of the knob (12, 13) and another surface (60) is sloping with respect to said axis. The emergency push-button according to claim 2, characterized in that said recess is provided with two pairs of opposing shaped surfaces (60, 61; 62, 63) of which a first pair (61, 63) is positioned parallel to the axis of movement of the knob (12, 13) and a second pair (60, 62) has surfaces sloping with respect to said axis. The emergency push-button according to claim 3, characterized in that said movable member (32) is connected to said knob (12, 13) by resilient means (22) which are loaded in a first direction parallel to the axis of said knob (12, 13) and in a second direction perpendicular to said axis of said knob (12, 13) to allow a) a first rotary movement of said movable member (32) in order to permit said retaining members (48) of the movable member (32) to snap on said protrusions (58), as said retaining members (48) move around said protrusions (58), or to clear said protrusions (58), b) an axial advancing movement of said retaining members (48) beyond said protrusions (58), and c) a second rotary movement in a direction opposite to that of said first rotary movement to ensure engagement of said retaining members (48) of said movable member (32) with said protrusions (58). The emergency push-button according to claim 3, characterized in that said retaining members (48) are retaining teeth. The emergency push-button according to claim 5, characterized in that said resilient means (22) comprise a first axially extending spring acting on said slider support (20) and which is charged through compression to allow advancing of said movable member (32) with respect to said protrusions (48), and a second spring acting on said movable member (32) to move around said protrusions (58) and then is discharged to carry said retaining teeth (48) under said protrusions (58). The emergency push-button according to claim 5, characterized in that said resilient means (22) comprise just one spring acting on said movable member (32) and strainable in an axial direction by compression and in a rotary direction by torsion in order to allow said retaining teeth (48) to move around said protrusions (58) to axially advance said teeth (48) beyond said protrusions (58) and to move said retaining teeth (48) back under said protrusions (58). The emergency push-button according to claim 5, characterized in that said resilient means (22) comprise at least one elastomeric sleeve acting on said movable member (32) and strainable by compression and by rotation in order to force said retaining teeth (48) to move around said protrusions (58) to axially advance said teeth (48) and to move said teeth (48) back under said protrusions (58). The emergency push-button according to claim 5, characterized in that said movable member (32) has a planar disk (34) at a lower end thereof and that said cam assembly (28) has an axial length smaller than a stroke permitted to said movable knob (12, 13) so that in case of breaking of said resilient means (22) a deeper stroke of said movable knob (12, 13) into said housing is always ensuring the movement thereof, even if a movement of said planar disk (34) is hindered by damages to controlled means. The emergency push-button according to claim 9, characterized in that said resilient means (22) comprise a pair of springs of which one operates by an axial movement of said knob (12, 13) and another operates by rotation of said knob (12, 13). The emergency push-button according to claim 9, characterized in that said resilient means (22) comprise just one spring constructed to be strainable by axial compression due to actuation of the push-button (12, 13), to remain compressed by engagement of said retaining teeth (48) under said protrusions (58) and to be subsequentely strained by torsion caused by a rotation of said knob (12, 13) to release said retaining teeth (48) from said protrusions (58). The emergency push-button according to claim 9, characterized in that said resilent means (22) is constructed to remain charged after said knob (12, 13) has been held lowered by said movable member (32) which in turn has been held by said retaining teeth (48) under said protrusions (58), said resilient means being further actuable by rotation of said knob (12, 13) in order to release said retaining teeth (48) from said protrusions (58) and to bring said knob (12, 13) back to a rest position thereof. The emergency push-button according to claim 12, characterized in that further comprises a cylinder lock (15) connected to said slider support (20) and suited to place the push-button (13) to a recovered position after actuation, said lock (15) being turnable by a key (17).

Inventors: FALCHI FIORINO, PARDINI FRANCO, FALCHI, FIORINO, PARDINI, FRANCO
Applicants: CGE SPA, CGE- COMPAGNIA GENERALE ELETTROMECCANICA S.P.A.
Application year: 1990
Main classification: H01H3
IPC codes: H01H3