[01] The invention relates to an over/underpressure valve for a socket on a cooking appliance, a socket with such a valve, as well as a cooking appli- ance with such a valve and/or with a socket. The invention more specifically focuses on commercial cooking appliances, in particular on commercial hot air steamers.

[02] Many types of cooking appliances are known. In commercial use, hot air steamers are suitable for many cooking tasks. They have a steam generator, the steam of which circulates inside the cooking chamber in particular due to forced convection. Other energy sources can be additionally provided for cooking the food to be cooked. [03] A particularly advantageous embodiment of a hot air steamer operates with a water drain closed by a siphon.

[04] More specifically in such an embodiment, at least one over/underpressure valve should be provided on the cooking appliance. If an over- pressure forms in the cooking chamber, it must be able to escape at any rate when it reaches a certain level. It is also necessary to compensate for or reduce an under-pressure at any rate when it exceeds a certain level, in order to prevent damage to the appliance or drain water to be sucked from the siphon into the cooking appliance. In a hot air steamer, a great underpressure regularly occurs when excess humidity contained in the air circulating inside the cooking chamber is condensed by injecting cold water. With such a mixed condensation, the volume of the fogged area in the condenser abruptly decreases, so that ambient air must abruptly be sucked into the cooking appliance.

[05] Providing such an over/under-pressure valve on a socket leading out of the casing of the cooking appliance is known. A disc rests outside on the socket with a circular cross-section. This disc closes the entire cross- section of the socket and protrudes slightly beyond it. A pin is centrally fastened to the disc - implemented by means of a star which extends inward from an edge area of the disc. The pin extends coaxially with the socket into it. It is located inside a guide sleeve which is disposed inside the socket - also via a star-shaped fastening. The pin is secured against being pulled out of the sleeve.

[06] The disc has several clearances between its outer ring and the central area from which the pin extends. These clearances are completely covered by a smaller disc on the side facing the inside of the socket. The smaller disc is pre-tensioned against the greater disc by means of a spring, but can be withdrawn by several millimeters from the greater disc toward the inside of the socket until it reaches a limit, if a force is applied to it. [07] During operation of a cooking appliance equipped with this, the over/under-pressure valve hermetically seals the socket under normal pressure conditions: the greater disc closes the tubular end of the socket and the smaller disc covers the clearances of the greater disc.

[08] If an excess overpressure builds up, the greater disc lifts off the tubular end of the socket in an axially outward direction. It is supported in this by the small disc because due to the higher pressure, it presses even more strongly from the inside against the clearances on the greater disc.

[09] The air can escape substantially radially through the vent between the tubular end of the socket and the outer disc. [10] A collar is usually disposed around this circular outlet, mostly a pipe section with a greater diameter. The collar diverts the air back into an axial direction and lets it exit the appliance. This prevents the escaping air that has been deviated in an orthogonal direction relative to the vertical axial direction from escaping for instance in the direction of the operating per- sonnel. They may indeed well stand approximately at face level with the upper edge of the casing of the cooking appliance. [11] Once the overpressure has been dissipated, gravity pulls both discs which are pre-tensioned against each other back down until the greater disc comes to rest on the socket. [12] If however an excess under-pressure occurs inside the cooking appliance, the greater disc is firmly sucked onto the socket and thus remains stationary. Due to the under-pressure, the small disc however lifts off the greater disc toward the inside of the socket. Air can thus stream in through the apertures in the greater disc, through the vent between the greater disc and the smaller disc and through the annular gap around the smaller disc.

[13] Once the under-pressure has been dissipated, the pre-tensioning spring pushes the small disc back against the greater disc. [14] The object underlying the invention is to provide an improved valve.

[15] According to a first aspect of the present invention, the object is solved by an over/under-pressure valve for a socket on a cooking appliance, more specifically on a commercial hot air steamer, with an opener opening outward for discharging overpressure and with an opener opening inward for discharging under-pressure, one of the two openers being mounted on the socket and the opener mounted on the socket having an edge guide opposing the socket. [16] The following terms must be explained:

[17] "Opening inward" refers to a direction of motion of one of the openers toward the inside of the socket, meaning ultimately with a socket mounted onto the cooking appliance, a direction of motion which yields to an air flow into the cooking appliance.

[18] Similarly, "opening outward" refers to a direction of opening which lets an air flow escape the cooking appliance through the socket.

[19] It must be assumed, that, as a rule, the "socket" constitutes a closure of the pipes leading out of the cooking appliance. In practice, it must be born in mind that a pipe or tube system inside the casing extends from the cooking chamber to be discharged or the air piping system to the wall of the casing. The "socket" is preferably set in the casing wall, mostly on an upper side of the casing.

[20] Such a configuration however is not mandatory. In fact, the entire "socket" can also be accommodated inside the casing of the appliance, or it can be located outside the casing.

[21] It is also possible to imagine constellations with several over/underpressure valves, these constellations having different types and places of installation. [22] Regarding "discharge", it must more specifically be born in mind to allow an overpressure or an under-pressure in the cooking chamber up to a certain limit, the over/under-pressure valve being activated for discharge only after this limit has been crossed.

[23] It is essential for the "socket" to have a closable pipe system, more specifically pipes with a round cross-section. [24] Regarding the mounting on the socket, it must be understood that at least one of the two openers should be guided by means of a firmly attached mounting. This mounting can be fastened on the socket if the socket as such constitutes a constructional element with the built-in over/underpressure valve. The same effect occurs of course if the mounting is not at- tached to the socket but for instance directly to the casing of the cooking appliance.

[25] At any rate, one of the two openers can be mounted to the other one. It makes sense for constructional reasons if a smaller opener is mounted on a bigger opener.

[26] In order to simplify readability, expressions using "at least" will be avoided as much as possible in the present application. A feature with an indefinite article "one", "two", etc. must thus always be understood as though it included the expression "at least", provided it does not result from the context that precisely such a number should be available.

[27] An "edge guide" must be understood as a guide, which takes over the task of guiding the opener along the edge of the opener and/or the socket. It should therefore be moved away from the axial guide in the middle. The latter indeed has the disadvantage that for a centrally disposed guided element on the opener, a guide must be centrally disposed in the socket. To that end it is necessary to encroach on the path of the air flow which in- creases the flow resistance and furthermore requires a rather high construction expense.

[28] In contrast, both the socket and the opener already feature an edge. It is thus considerably easier in terms of construction to directly use at least one of the two edges which are already available for guiding.

[29] A reliable guide becomes particularly important more specifically when the displaced edge-guided opener must return merely by means of gravity.

[30] An edge guide already exists when the guide is only disposed at one point or a portion of the edge.

[31] It is preferable however to use the entire edge as a guide. [32] It is preferable if the opener mounted on the socket carries the other opener in a spring-mounted manner. A guide can also be provided at the edge or even preferably in a central area for the spring-mounted connection.

[33] It is proposed that both openers are connected to each other via a pin and a sleeve. Such a design can have a small configuration, a spring being easily integrated. [34] The openers themselves can be manufactured in many different designs. Discs or cups provide particularly simple designs. Metal is suitable as a construction material but other construction materials more specifically such as plastic material can also be used. [35] The surface which actually closes the socket is preferably positioned orthogonally to a direction of flow through the socket. It is preferably discshaped.

[36] The edge guide can have extensive clearances.

[37] A "clearance" on the edge guide must more specifically be understood as an arrangement in which the edge guide exists at least on a constructional element, otherwise as a collar-type area, for instance as a cylinder barrel. [38] The extensive clearances are supposed to be present in the edge guide. They make it easier for the air to escape. This design particularly makes sense when the edge guide must serve for displacement, more specifically lifting, in the function of the overpressure valve. The excess pressure then pushes the corresponding opener along its preferably linear edge guide mainly upwards out of the socket. The collar-shaped edge guide firmly connected to the opener, for instance a plane cover, is accordingly lifted at least partially out of the socket. In order for the air to escape more easily, the clearances are provided in the collar. The air can then escape not only through the vent between the collar and the socket but additionally in a radial or diagonal direction through the clearances out of the inside of the collar and over the edge of the socket into the ambient air. [39] In order to facilitate the escape or inflow of air, it is proposed that the cut surface of the edge guide is greater than its remaining surface.

[40] In an extreme development, the edge guide consists only of a few guide bars. Broader, disc-shaped bars are also possible.

[41] In general, it would have to be possible to assume that a greater surface of the edge guide supports a secure gliding of the opener in both directions and reduces the risk of it getting jammed. [42] The inventor considers configuring the edge guide as a toothed ring as a good compromise between openness and available guiding surface at the edge guide. The multiple teeth run respectively parallel to the outline of the socket, that is for instance in the shape of a circular ring segment. A sufficient space remains however between the teeth for the air to flow through.

[43] The toothed ring can for instance have a wave-shaped outline. [44] The edge guide has a longitudinal extension in relation to the outlet direction of the opener, which in the simplest case is linear and coaxial to the socket. The toothed ring should have an extension of at least 1 cm, or preferably 2 cm in the axial direction. With a sufficient extension, the opener can distinctly lift off its closed position when it opens.

[45] It should furthermore be born in mind that when the socket is installed on the cooking appliance, it can have a collar in form of a beveled pipe section which continues like a chimney. [46] The socket and the valve are preferably matched in such a manner that the chimney-type collar on the socket is higher than a lift of the opener opening outward, but that the measure of the projection is as small as possible, so that in its opened position, the opener opening outward preferably rises to less than 5 mm from a lowest point of the chimney-type collar. [47] In order to be able to securely maintain the open position, the opener opening outward can be secured to the socket by means of an anchor. In a simple case, such an anchor can be a chain or a bar which moves together with the opener opening outward during its opening motion, a bolt, which is for instance firmly connected to the socket or can be disposed in it so that it can move up to a certain limit, being provided at the bottom of the chain or bar. [48] It is understood that a socket as described above, more specifically equipped with an over/under-pressure valve is advantageous.

[49] The same applies to a cooking appliance which is equipped with such a valve and/or socket.

[50] An exemplary embodiment of the invention is described in more detail in the following with reference to the drawings. In the drawings:

Figure 1 shows a front view of a vertical socket for a cooking appliance with a built-in over/under-pressure valve,

Figure 2 shows a section through the socket and the over/under- pressure valve from figure 1 according to the markings II - II in figure 1, Figure 3 shows a top view onto the socket with the over/under-pressure valve from figures 1 and 2 according to the markings III - III in figure 2, and

Figure 4 shows a three-dimensional view of the socket with over/underpressure valve from figures 1 to 3.

[51] The socket 1 in the figures is provided for being inserted into a casing of a cooking appliance. There an outer part 2 of it should protrude vertically upward out of the casing of the cooking appliance, while an inner part 3 should be disposed inside the cooking appliance usually made of sheet metal. [52] The outer part 2 substantially consists of a cylindrical collar 4, which is disposed coaxially to an axial direction 5 of the socket. An upper side 6 of the collar 4 is beveled, thus resulting in a higher area 7 and a lower area 8 of the collar 4. [53] The collar 4 is hollow inside. It consists only of a sheet metal which forms the cylinder barrel. The latter is closely connected to a bottom sheet metal plate 9. [54] The inner part 3 of the socket 1 has a considerably more complex configuration:

[55] It substantially consists of a pipe socket 10 through which air can flow in different directions in case of an over or under-pressure. An O-ring 13 made of a silicone for instance is disposed outside the pipe socket 10 in an axial fixation by means of two flanges 11, 12.

[56] While the bottom plate 9 is destined to be fit directly on a pipe 14 of a cooking appliance (not shown), the inner part 3 is substantially destined to be inserted into the pipe 14 (only shown in figure 1), the O-ring 13 providing for a hermetical seal.

[57] From an axial perspective, the over/under-pressure valve 17 lies be- tween an inner area 15 of the pipe 14 - and thus of the cooking appliance - and an outer area 16 with ambient air.

[58] The over/under-pressure valve 17 substantially consists of a cup- shaped first opener 18 and a disc-shaped second opener 19 in the form of a valve disc.

[59] The cup-shaped first opener 18 is composed of a big disc 20 and a toothed ring 21 with teeth 22 (exemplarily labeled) attached to it. [60] The big disc 20 has a circular outer outline which slightly protrudes from the pipe socket 10 due to its dimensions, so that it rests tightly on the pipe socket 10 in a ring-shaped contact point 23. It is however not firmly attached there, but rather freely movable.

[61] The big disc 20 has a continuous ring-shaped edge area 24 with three extensive apertures 25 (exemplarily labeled). Three radial bars 26 (exem- plarily labeled) are arranged in shape of a star between the three apertures 25 and converge into a small ring 28 in a center 27 through which a central axis also runs. This ring has an orifice 29 in its center for a screw or a pin 30.

[62] The pin 30 is secured against sliding through the small ring 28 into the inner area 15 by means of a first front flange 31. On its other side, it has a second front flange 32. A spiral spring 33 is mounted there. The spiral spring 33 extends from the second front flange 32 disposed inward, in the direction of the outer area and is pre-tensioned there against the discshaped second opener 19. The disc-shaped second opener 19 is therefore maintained by the pre-tension of the spiral spring 33 against the extensive apertures 25 of the big disc 20 of the cup-shaped first opener 18 and closes them. -

[63] The teeth 22 of the toothed ring 21 have the same pronounced wave- shaped run in which the surface equipped with teeth 22 is approximately the same as the surface equipped with clearances 34 (exemplarily labeled). The radial diameter of the toothed ring 21 is marginally smaller than the pipe socket 10, so that the cup-shaped first opener 18 can only deviate inside the pipe socket 10 by a very small angle relative to the axial direction 5, even when the cup-shaped first opener 18 only extends into the pipe socket 10 with a small section of the toothed ring 21.

[64] An anchor-shaped element in form of a wire is attached to a chain at a lower end 35 of the pin 30.

[65] It is suspended at equilibrium, so that two limbs protrude radially the same distance. In their radial extension in relation to the axial direction 5 and thus to the central axis of the socket 1, the two limbs extend beyond the pipe socket 10 but are smaller than the pipe 14 coming from the cook- ing appliance.

[66] During operation of the cooking appliance and thus of the socket 1 with its over/under-pressure valve 17, the clamping of the O-ring 13 at first provides a secure sealing of the inside of the cooking appliance, particu- larly of the cooking chamber, with which the inner area 15 is connected, against the outer area 16. Air cannot enter respectively escape next to the O-ring 13, nor through the pipe socket 10, since the pipe socket 10 is closed radially inward by the cup-shaped first opener 18, in practice by its big disc 20, and by the disc-shaped second opener 19. [67] Gravity seals the over/under-pressure valve 17 against overpressure in the inner area 15 by means of the cup-shaped first opener 18, the discshaped second opener 19, the spiral spring 33 and the anchor-shaped ele- ment 36 as well as the connecting chain.

[68] If the upward force resulting from an overpressure in the inner area 15 is greater than this weight, the unit listed above, substantially the entire over/under-pressure valve 17, lifts off from the contact point 23 of the pipe socket 10 toward the outer area 16. The toothed ring 21 lifts out of the pipe socket 10 to the same degree. The air can escape diagonally upward through the very extensive clearances 34 into the collar 4 of the outer part 2 of the socket 1 and out. [69] Once the discharge of the overpressure has occurred, gravity leads the over/under-pressure valve 17 back to a neutral position shown in the figures.

[70] When leaving the pipe socket 10, the over/under-pressure valve 17 is guided linearly along its toothed ring 21. Since the toothed ring 21 is mechanically engaged with the pipe socket 10, in order to prevent a jam at a very short angle, and since the toothed ring 21 is located at the ring-shaped edge area 24 of the big disc 20, the toothed ring 21 interacting with the pipe socket 10 serves as an edge guide in the present invention. [71] Losing the oyer/under-pressure valve 17 when it lifts out of the pipe socket 10, which in turn is attached locally to the pipe 14 by clamping, is prevented by the anchor-shaped element 36. An axial leeway 37 between the anchor-shaped element 36 and its necessarily occurring impact on the pipe socket 10 is smaller by a few millimeters than an axial length 38 of the teeth 22. When the over/under-pressure valve 17 leaves the pipe socket and the anchor-shaped element 36 hits against the pipe socket 10 from below, a few millimeters of the teeth 22 and thus of the axial edge guide are thus still inside the pipe socket 10. This ensures that the over/underpressure valve 17 falls safely back into the pipe socket 10 when the overpressure decreases.

[72] In case of an under-pressure, the over/under-pressure valve 17 is shut tight until the force resulting from the under-pressure in the inner area 15 onto the disc-shaped second opener 19 exceeds the pre- tensioning force of the spiral spring 33. When this happens, the disc-shaped second opener 19 lowers toward the inner area 15 against the force of the spiral spring 33. Air can then enter from the outer area 16 into the inner area 15 through the apertures 25.

[73] Once the under-pressure has been relieved, the spiral spring 33 reliably closes the disc-shaped second opener 19 against the cup-shaped first opener 18. List of reference numbers

1 Socket 20 Big disc

2 Outer part 21 Toothed ring

3 Inner part 22 Tooth

5 4 Collar 23 Contact point

5 Axial direction 25 24 Ring-shaped edge area

6 Upper side 25 Aperture

7 High area 26 Bar

8 Lower area 27 Center

10 9 Bottom plate 28 Small ring

10 Pipe socket 30 29 Orifice

11 Flange 30 Pin

12 Flange 31 First front flange

13 O-ring 32 Second front flange

15 14 Pipe 33 Spiral spring

15 Inner area 35 34 Clearance

16 Outer area 35 Bottom end

17 Over/under-pressure valve 36 Anchor-shaped element

18 Cup- shaped first opener 37 Axial leeway

20 19 Disc-shaped second opener 38 Axial length