United States Patent 3861080

An aperture, in a rigid housing enclosing a space or volume, is closed by utilizing a cover opening under explosive pressure and cooperating with the housing. The cover is maintained closed by exerting, between the cover and the housing, an elastic holding force which collapses abruptly to zero value on being overcome by explosive pressure within the housing. The cover may be hinged to the housing and may be provided with detent means for releasably latching it in the closed position. Where the housing aperture is of substantial size, two such covers may be used.

Schibli, Elmar (Niederwil, CH)
Kentsides, Constantin (Oberuzwil, CH)
Application Number:
Publication Date:
Filing Date:
Gebrueder Buehler AG (Uzwil, Gallen County, CH)
Primary Class:
Other Classes:
49/141, 49/394, 52/1
International Classes:
E04B1/98; E06B5/12; (IPC1-7): E05F15/20
Field of Search:
49/31,141,394 52
View Patent Images:
US Patent References:
2358143Vented panel1944-09-12Castor
1887484Explosion-release mechanism for windows1932-11-08Walton

Primary Examiner:
Downey, Kenneth
Attorney, Agent or Firm:
Mcglew, And Tuttle
What is claimed is

1. An apparatus for closing an aperture, in a rigid machine housing enclosing a space, by utilizing a cover opening under explosive pressure and cooperating with the machine housing, the improvement comprising, in combination, respective structural parts correlated with the boundary of the aperture formed in the machine housing and with the cover; an elastically releasable locking device installed between such respective structural parts and constructed and arranged so that, responsive to an explosive pressure within the machine housing, the initial restraining force of the locking device is overcome and the cover is abruptly moved from a stable, closed position to a tension-free open position clearing the aperture in the machine housing; said locking device comprising two detent elements elastically displaceable relative to each other; one element being connected with the cover and the counter element being connected with that portion of the machine housing bounding the aperture; the cooperating ends of the two elements being respectively convex and concave for interengagement with each other; an articulated suspension mounting the cover on the machine housing; a guide sleeve pivotally mounted on the cover between the articulated suspension and the opposite edge of the cover and extending perpendicularly to the articulated suspension; a pull rod slidably engaged in said guide sleeve; a compression spring embracing said pull rod between said guide sleeve and an end plate adjacent one end of said pull rod; and a pivot suspension at the other end of the pull rod mounted on another part delimiting the aperture.

2. An apparatus for closing an aperture, as claimed in claim 1, in which said pivot suspension is mounted on the machine casing at the periphery of the aperture.

3. An apparatus for closing an aperture, as claimed in claim 1, in which said pivot suspension is mounted on a second cover cooperating with the first-mentioned cover to close the aperture.

4. An apparatus for closing an aperture, as claimed in claim 3, in which said pivot suspension comprises a pivotal guide sleeve displaceably embracing said pull rod; and a second compression spring embracing the pull rod between said last-named guide sleeve and said other end of said pull rod.

5. An apparatus for closing an aperture, as claimed in claim 1, in which, when the cover is closed, said compression spring rests loosely on said pull rod and is tensioned to a certain value at a predetermined maximum opening of the cover.

6. An apparatus for closing an aperture, as claimed in claim 1, in which said compression spring has a progressive spring force characteristic.


This invention relates to a method for closing an aperture in a rigid housing enclosing a space, by utilizing a cover opening under explosive pressure and cooperating with the housing.

The problem underlying the invention is to provide housings of processing units, which foreseeably may possibly be seriously damaged by explosion-like detonations or by actual explosions occurring within the housing, with one or more explosion-relief apertures. These apertures are to be closed by explosion-relief covers in a manner such that each closure satisfies the following conditions.

The aperture in the machine housing is to be closed in such a way that, under normal material processing occurring inside the machine housing, both the machine housing having the aperture, on the one hand, and especially the cover fitted in the housing to close the aperture, on the other hand, act conjointly as one rigid machine housing.

When explosion-like detonations, or actual explosions, occur within the machine housing, there is a very rapid response in that the cover clears the largest possible area of the aperture in a very short time for relief of the pressure within the housing.

The closure must provide the smoothest possible surface toward the inside of the machine housing, that is, toward the processing space enclosed by the housing.

If possible, the cover should be suspended in an articulated manner on the machine housing to avoid complete separation of the cover from the housing.

Finally, the cover should be easily installed.

It is especially important to provide such explosion-relief devices in processing plants of the chemical industry and in shredding and transport systems in garbage processing. In other words, the sector in which the objective of the invention is important comprises processing plants which, with a very great probability, are imperiled by explosion-type detonations or by actual internal explosions, so that an additional condition, besides those mentioned above, must be fulfilled. Namely, there must be no need for maintenance over very long periods of time.

In addition, it is desirable, in very many cases, that the opening path of the explosion-responsive dampers, covers, or flaps be limited, and that, when an opening movement of the damper takes place for the relief of an explosion, an elastic limitation of the opening path is assured. Thereby, damage to the aperture closing device as a whole and of the damper or cover suspension in particular need not be suffered.

For certain cases, it is necessary, moreover, that large relief apertures are to be closed by two pivoted dampers or covers. For this condition, a locking system must be provided which gives the same assurances of safety and operation with the same principle.

A significant application of such dampers, for closing an explosion-relief aperture, is in shredding devices, in particular devices for the shredding of garbage, in that occasional unpredictable detonations and explosions may occur therein and lead to considerable damage.

From the foregoing, it will be appreciated that the use of such dampers or covers involves two contradictory conditions. That is, during normal operation of the shredding device, the damper must close the aperture absolutely tightly. On the other hand, when small explosions, or explosion-like detonations occur, the damper must open reliably, quickly and as widely as possible.

In endeavoring to find a suitable solution for these apparently contradictory requirements, it must be realized that, during shredding, parts are hurled against the damper and their kinetic energy is dissipated by impact with the damper. This load on the damper, however, is so local as not to cause opening of the damper. By contrast, the explosive pressure produced in a detonation or explosion in the space closed off by the damper and the housing exerts itself uniformly over the entire damper area. Thereby, even at relatively small detonations, forces in the amount of the product of the damper area and the explosive pressure, become operative on the locking mechanisms, and these forces are able to overcome the locking forces of the locking mechanisms only if the design of the locking mechanism is suitable. Thus, the problem to be solved resides primarily in suitably designing the locking mechanism taking into consideration the mentioned conditions.

In accordance with the invention, a method for solving this sphere of the problem is characterized in that the cover is held in the closed position by an elastic holding force exerted between the housing and the cover, this elastic holding force collapsing abruptly to zero value on being overcome by explosive pressure within the housing. In the closed position, the elastic holding force can hold the cover in a stable position, and it is only upon being overcome by the explosive pressure that the holding force collapses to zero so that the cover can occupy an unstable position.

The invention is also directed to apparatus for performing the method, and this apparatus is characterized in that, between two structural parts, correlated, on the one hand, to the boundary of the aperture formed in the machine housing which encloses the space and, on the other hand, to the cover, there is installed an elastically releasable locking device. This device is installed in such a manner that, responsive to an explosive pressure, an initial tension provided by the locking device is overcome, and the cover is moved suddenly from a stable closed position to a tension-free open position clearing the aperture in the housing.

The cover may be mounted pivotally on the machine housing for elastic connection with the housing.

The locking device may have two detent elements which are elastically displaceable relative to each other, one element being connected with the cover and a counter element being connected with the fixed boundary of the aperture closed by the cover. The detent element and the counter element have mating convex and concave, or vice versa, interengaging surfaces.

Locking may be effected with the use of a combination of two detent elements, elastically displaceable relative to each other, of which one element is assigned to the damper or cover and the counter element to the boundary of the aperture closed by the damper, with the detent action being effected by cooperation of convex and concave mating surfaces. At least one of the elements may be designed, depending on the correlation, to be adjustable to the tensioned closed position and to an unloaded or untensioned open position. The correlation of the two interlocking elements can be effected either between the damper and the boundary of the aperture, or between two dampers, by suitable correlation.

To limit the opening movement of the dampers closing the explosion-relief aperture, there may be provided, opposite the articulated suspension, a pull rod, also mounted in an articulated fashion, which receives, between the articulated suspension and its end, a guide sleeve connected with the damper. A compression spring is interposed between this guide sleeve and the pull rod opposite the mounting of the pull rod. The compression spring may be designed to have progressive spring action and, in the closed state of the damper, the spring is completely unloaded.

An object of the invention is to provide an improved method of closing an aperture in a rigid housing enclosing a space, by utilizing a cover opening under explosive pressure and cooperating with the housing.

Another object of the invention is to provide improved apparatus for closing an aperture in a rigid housing enclosing a space, by utilizing a cover opening under explosive pressure and cooperating with the housing.

A further object of the invention is to provide such a method and apparatus in which the cover is held in closed position by an elastic holding force exerted between the cover and the housing, the elastic holding force suddenly collapsing to zero upon being overcome by explosive pressure.

Another object of the invention is to provide such a method and apparatus in which the cover, responsive to explosive pressure, is moved from a stable position closing the aperture to an unstable position clearing the aperture.

For an understanding of the principles of the invention, reference is made to the following description of typical embodiments thereof as illustrated in the accompanying drawing.


In the drawing:

FIG. 1 is a longitudinal sectional view through an embodiment of the invention illustrating the cover partially opened;

FIG. 2 is a sectional view illustrating a cover locking system having two different adjustment possibilities; and

FIG. 3 is a longitudinal sectional view illustrating a double damper closure embodying the invention.

In the embodiment shown in FIG. 1, an explosion-relief aperture 102 is provided in a fixed casing 101 enclosing a processing space 100. To close aperture 102, there is provided a cover 103 which, along its periphery, has a packing strip 104 resting on casing or wall 101. Cover 103 is articulatedly or hingedly mounted through straps or ribs 105 engaging hinge pins 106 in straps or ribs 107 secured to casing or wall 101. Opposite the hinged suspension 105, 106, 107 of cover 103, there is mounted one of two elastically interlocking elements, of which the element 110 is composed as will now be described. Element 110 includes a housing 111 fixedly connected with cover 103. A displaceable detent element 112 is provided in housing 111, and has a convex detent head 113 and a stop 114 for engaging housing 111. Housing 111 also encloses a compression spring 115, preferably formed by several plate springs. The housing also has mounted therein a tension-adjusting device 120 comprising a screw 121 having a head 122 and a lock nut 123 arranged thereon, together with a pressure plate 124.

Cooperating with the locking device 110 there is a counter part 130 which is secured to wall or casing 101. Counter element 130 is formed, as an essential feature, with a concave detent recess 131 and, in certain cases, it is advantageous that the entry into this detent recess 131, as referred to the detent element 112, presents an inclination 132 so that closing of the cover and engagement of detent element 112 into detent recess 131 is effected more easily.

To limit the opening movement of cover 103, a pull rod 150 is pivotally mounted in straps or ribs 141 on wall or casing 101 through the medium of a pivot pin 142 and a hinge strap 143. A guide sleeve 146 embraces pull rod 150 and is rotatably or oscillatably mounted, through the medium of a bearing pin 147, in a bearing block 148 fixedly connected with damper or cover 103. The free end of pull rod 150 is provided with a threaded pin 151 and an end plate 152 retained by a nut 153, and end plate 152 has an abutment face 154. Between guide plate 146 and end plate 152 there are arranged, successively, a first compression spring 155, an intermediate disk 156, and a packet of plate springs forming a second compression spring 157. The helical compression spring 155 bears against an end face 158 of intermediate disk 156, while one end of plate spring 157 bears against the opposite end face 159. It is characteristic of the spring arrangement that, up to a certain opening movement of cover 103, the spring arrangement rests entirely loosely on pull rod 150, as is clearly visible from FIG. 1, by the space between end plate 152 and the uppermost plate spring of the spring 157.

With damper or cover 103 closed, plate spring packet 115 is charged, in locking device 110, upon engagement of the convex end 113 of element 11 into the concave detent recess of counter element 130, by adjustment of screw 121, to an extent such that the stress on cover or damper 103, occurring during normal operation of the device closed within casing 101, will not overcome the holding force. However, when an explosion occurs in the space 100, the interengaging locking is released by the pressure acting over the entire surface of cover 103.

At the beginning of the opening of cover or damper 103, element 112 is displaced, against the bias of compression spring 115, until convex head 113 moves over the edge of concave detent recess 131. Immediately thereupon, cover or damper 103 turns about pivot axis 105 at very great speed outwardly into the open position. With increasing opening movement of the cover away from a certain opening point, first compression spring 155 is compressed over a relatively long path. Thereby, the opening speed is decelerated for the first time. Following this compression of compression spring 155, the remaining deceleration of the opening a movement of cover 103 is provided by compression spring 157 until the movement of cover 103 is completely arrested. In certain cases, this now existing charging of the springs is sufficient to move the cover back toward the closed position.

With the arrangement shown in FIG. 1, it is possible to relieve the pressure waves of explosions, propagating at great speed (up to 400 m/sec.), in fractions of a second by overcoming small closing forces, into the opening or respectively into the free space surrounding the protected space 100. Additionally, this damper lock permits repeated use, which is not the case when burst plates are used. The elastic opening movement delimiting device permits braking the opening movement within a relatively long opening path and from the very great opening speed to zero, without this brake work being transformed into deformation work at the cover or at a housing part carrying the cover.

In the embodiment of the invention shown in FIG. 2, and similarly to the design shown in FIG. 1, a single cover 103' is mounted, by straps 105' in hinge pins 106', in bearing straps 107' which are connected with casing or wall 101'. The limitation of the opening path of cover 103' is again effected, on the one hand, by the articulated suspension 141', 143' for pull rod 150' and, on the other hand, guide sleeve 146' with bearing pin 147' engaged in bearing block 148' connected with cover 103'. However, for simplification, the springs which are used are not shown.

In contrast to the design according to FIG. 1, the locking device no longer acts between a counter element 130 at the fixed frame, through detent device 110, on cover bearings 105, 106, 107, but by twin arrangement, as will now be described, through a self-enclosed system.

A detent device 110' is firmly connected with wall or casing 101', and comprises a housing 111', a compression spring 115' arranged in the housing, and a screw 121' with a head 122', a lock nut 123' and a pressure plate 124° for the adjustment of spring 115'. A detent ball 163° is used as the detent element. Directly aligned with the combination comprising screw 121', spring 115' and detent ball 163', and at a given spacing therefrom, there is a tension device 170 also connected with wall or casing 101'. To determine the spacing, an intermediate detent element 160 is fixedly connected with cover 103' and extends over the edge of the cover or damper into the zone of detent device 110' and device 170 aligned therewith. In the zone of devices 110' and 170, detent element 160 is provided, on opposite sides, with detent recesses 161, there being provided, in the instant design, a continuous bore 162 extending from one detent to the other, solely for manufacturing reasons.

Tensioning device 170 comprises the housing 111" having a compression spring 115" arranged therein, and a detent ball 163". For the purpose of tensioning spring 115" through detent ball 163" relative to detent recess 161 in element 160, a toggle lever tensioning system is provided. This toggle lever tensioning system comprises a mounting element 171, firmly connected with casing or wall 101', a tensioning lever 172 pivoted in mounting 171 by a bearing pin 173, a toggle joint pin 174 articulatedly connecting lever 172 with an intermediate strap 175, a strap pin 176 pivotally connecting strap 175 with the head 177 of a pressure bolt 178, a pressure plate 180 engaging compression spring 115', and a slide bearing 181 connected with support 171 for slidably mounting pressure pin 178.

Functionally, that is, as far as the closing safety under normal operation and the opening upon explosions is concerned, there is no basic difference in the design of FIG. 2 from that of FIG. 1. However, in the construction of the embodiment of FIG. 2 and, as a result thereof, in the response sensitivity for opening of the damper or cover, there are differences. Thus, the action and reaction forces in the locked state are no longer closed by the detent device through the cover suspension and the fixed housing. Instead, there exists a closed circle of forces between the two detent and tensioning devices 110' and 170, through the intermediate detent element 160 and the fixed housing 101'. Thus, cover suspension 105', 106', 107' is relieved of these forces.

Tensioning device 170, having the toggle lever system, permits, after completed opening of cover 103', a very simple reclosing in that tensioning device 170 can be released very simply by lifting tensioning lever 172 and hence by corresponding relief of compression spring 115", which consists of a plate spring packet, to close the damper. It is only then that the locking force is again built up to the predetermined value, namely exactly the same as before, by pivoting tension lever 172 to its abutment against end stop 182. It is advantageous to use similar tensioning devices 170 on both sides of the intermediate detent element 160.

The opening path limiting device embodying the pull rod 150' and the springs arranged therein, as shown in FIG. 1, can be used without change and, it is advantageous to arrange these limiting devices in pairs, one on each side of the cover. Thus, in the embodiment of FIG. 2, there is provided a solution where, for opening of the cover, no additional bearing friction forces originating from the locking device need be overcome during the opening process, which latter must occur very rapidly, in that these, as stated, are no longer present as reaction forces.

The embodiment of the invention shown in FIG. 3 is substantially analogous to that shown in FIG. 2, and includes two cooperating covers 103" and 103'" with respective packing strips 104" and 104'", for closing larger relief apertures. The suspensions of the covers 103" and 103'" are effected, in the same manner as in FIGS. 1 and 2, through straps 105", 105'", hinge pins 106", 106'" and bearing straps 107", 107'".

In the same manner as in FIG. 2, tensioning device 170 is arranged double so that, through casing or wall 101", a closed force system is present. Consequently, two tensioning devices 170' and 170" are firmly connected with casing or wall 101" which contains the explosion-relief aperture to be closed by covers 103", 103'", and in turn these tensioning devices consist of the same parts as in FIG. 2, including the toggle lever system. The two devices are positioned on the same axis, and are so disposed that the detent recesses of intermediate detent element 160', which is secured to the lower damper 103'" and projects over the edge thereof, fit between the balls 163'" and 163"" of the respective tensioning devices 170' and 170". Thus, in contrast to FIG. 2, two tensioning devices with toggle lever systems are used.

While the locking system of FIG. 3 differs insignificantly from that shown in FIG. 2, there is a difference in the opening path limiting device. Near the lateral edges of covers 103" and 103'" there are fixed respective bearing blocks 148" and 148'" at approximately equal distances from the pivot axes of the respective covers. By correspondingly correlated bearing pins 147" and 147"", guide sleeves 146" and 146'", for pull rod 150", are rotatably mounted in the respective bearing blocks. At the two ends of pull rod 150" there are, in the same manner as in FIGS. 1 and 2, arranged, from the center outwardly, but shown as a whole only at the top, first compression springs 150', 150", then plate spring packets 157' serving as compression springs, and furthest out the nuts 153' which permit adjustment of the opening paths of the covers. In principle, this opening path lmitation involves the same system as in FIGS. 1 and 2, with the difference that pull rod 150", which is articulated to covers 103" and 103'", is no longer mounted on casing or wall 101" but is guided in parts secured on covers 103" and 103'".

Functionally, there results slight differences from the first two variants. In the closed position of the two covers, the upper cover is held by the packing strip of the lower cover. Pull rod 150", by its dead weight and the lower springs guided thereon, slides down far enough to be retained in an end position through springs 150' and 157', correlated to the guide sleeve 146", as well as the nut 153'.

In case of an explosion, the explosive pressure acts largely uniformly on both covers 103" and 103'". Through the packing strip correlated with damper or cover 103'", which seals the upper cover, this explosive pressure acts also on tensioning devices 170' and 170" which, through intermediate detent element 160' with the two detent recesses 161', hold the covers in the closed position. For the opening of the covers, the spring forces of both tensioning elements 170' and 170" must be overcome, and then both covers pivot outwardly about their bearings. During the opening movement, pull rod 150" slides up through the lower guide sleeve 146'". It is only when the lower spring 150" bears against guide sleeve 146'" that the elastic limitation of the opening movement commences, in that the two springs 155' and 155" are tensioned, substantially alike, simultaneously. Subsequently, there occurs the elastic deceleration of the cover opening movement by the plate spring packets. Instead of the arrangement of covers 103" and 103'" one above the other, these may alternatively be mounted with vertical pivot axes 106" and 106'" horizontally side-by-side on the housing, for the same mode of operation.

Despite the functionally minor difference of the embodiment of FIG. 3 from that of FIGS. 1 and 2, it is nevertheless notable inasmuch as, with very simple means, a large explosion-relief aperture can be provided and securely closed, and no disadvantageous forces must be overcome during the opening movement, especially in the bearings.

It will be clear that various structural elements and structural measures may also be used, which are different from those shown in the drawings, so that equivalent structure elements may be regard as coming within the scope of the invention. The essential feature for the invention is the safe closure in normal service and the rapid opening of the damper or cover when an explosion occurs. Because of the high opening speed, it is advantageous to use, in addition to the locking system, an elastic limitation for the opening path.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.