Valve with a backflow preventer

Abstract

Valve comprising a valve body (23), a main valve (5), and a non-return valve (13), wherein the valve body (23) has an upstream valve inlet (2), an downstream valve outlet (3), and a flow channel (4) for connecting the valve inlet (2) to the valve outlet (3), wherein the main valve (5) and the non-return valve (13) are arranged in the flow channel (4), wherein the non-return valve (13) has a valve seat (14) and a closing element (15) for opening and closing the valve seat (14), wherein the valve seat (14) is integrally formed on the valve body (23), and wherein the closing element (15) is controllable via a first control chamber (16) and a second control chamber (17), wherein the first control chamber (16) is part of the flow channel (4), characterized in that the non-return valve (13) is located between is arranged at the valve inlet (2) and the main valve (5).

Description

[0001] The present invention relates to a valve according to the preamble of patent claim 1. A further subject of the invention is a method for operating such a valve.

[0002] Valves are used in various fields of technology to switch fluids. A fluid flows into the valve via a valve inlet. The valve inlet is connected to the valve outlet via a flow channel, to which the fluid flows along a main flow direction of the valve. The fluid can then exit the valve through the valve outlet. The valve inlet, the valve outlet, and the flow channel are part of a single- or multi-part valve body.

[0003] To switch the fluid flow, a main valve is located in the flow channel. This main valve can block the flow channel in its closed position, preventing the fluid to be switched from flowing through the flow channel from the valve inlet to the valve outlet. In its open position, the main valve releases the flow channel, allowing the fluid to be switched from the valve inlet to the valve outlet.

[0004] The pressure of the fluid to be switched can be used to actuate the main valve. For example, in a main valve designed as a servo valve with a main valve seat and a diaphragm-shaped main closing element, the fluid can exert a pressure on the valve inlet side on both sides of the main closing element, while a lower pressure prevailing on the valve outlet side is exerted on the remaining surfaces of the main closing element. By influencing the ratio of the surfaces of the main closing element facing towards and away from the main valve seat, to which the respective pressures are exerted, the main valve can be optionally opened or closed. In the closed position, the fluid acts with the valve inlet side pressure on a larger surface of the main closing element facing the main valve seat than on a surface facing away from the main valve seat.Consequently, a greater force acts on the main closing element toward the main valve seat than away from it, so that the main closing element is pressed against the main valve seat with a resulting force. To move the main valve to the open position, the pressure on the surface facing away from the main valve seat can be reduced to the pressure on the valve outlet side, and thus also the force acting on the main closing element toward the main valve seat. The fluid to be switched pushes the main closing element away from the main valve seat with a resulting force, and the main valve opens.

[0005] However, with such valves, a backflow of the fluid to be switched can occur, counter to the main flow direction. In particular, a drop in the pressure at the valve inlet can lead to a relative negative pressure compared to the valve outlet when the main valve is closed. This can result in a force acting away from the main valve seat on the main closing element, causing the main valve to open unintentionally. The fluid can then flow from the valve outlet to the valve inlet via the open main valve.

[0006] To prevent such backflow, check valves, such as a check valve, are installed in the valve inlet or outlet in the flow channel of the valve body. A check valve connected in series with the main valve allows the fluid to flow only in the main flow direction. As soon as the fluid is sucked back toward the valve inlet by the negative pressure on the valve inlet side, causing the fluid to flow back from the valve outlet to the valve inlet, the resulting backflow of the fluid causes the check valve to close, thus blocking the flow channel.

[0007] Backflow preventers typically have a valve seat and a closing element for opening and closing the valve seat. The closing element interacts with the valve seat to close the backflow preventer, preventing fluid from flowing back.

[0008] These backflow preventers are usually designed like a cartridge, which is inserted into the valve inlet or outlet as an additional element. This insertion of the backflow preventer only takes place during assembly of the valve by a technician in the factory or at the installation site, for example, when the valve is installed into a domestic piping system. Since the backflow preventers must be inserted separately into the valve, their use involves a certain amount of installation work at the installation site. Furthermore, the use of such backflow preventers is associated with various sources of error and is therefore highly prone to errors. For example, the backflow preventer can simply be forgotten during assembly or after disassembly for maintenance purposes, or it can be inserted in the wrong orientation.These defects mean that backflow of fluid from the valve outlet to the valve inlet is no longer prevented or the fluid can no longer flow from the valve inlet to the valve outlet if the backflow preventer is installed in the reverse orientation.

[0009] EP 1 435 495 A2 relates to a switching valve arrangement with two valves. DE 24 14 893 A1 deals with a combined backflow prevention and anti-siphon valve. A backflow prevention device with two valves is known from DE 103 11 252 B3.

[0010] The object of the present invention is to provide a valve and a method for operating such a valve, with which backflow can be prevented with a high degree of reliability and at the same time a low assembly effort and a low risk of assembly errors can be achieved.

[0011] This object is achieved in a device of the type mentioned at the outset by the characterising features of patent claim 1.

[0012] Due to the one-piece arrangement of the valve seat on the valve body, the valve seat and the valve body form a solid structural unit. The backflow preventer thus forms part of the valve. The valve seat determines the orientation of the backflow preventer. Since the captively arranged backflow preventer does not have to be inserted into the valve during assembly, but forms part of the valve, it cannot be forgotten or inserted incorrectly. Losing the entire backflow preventer is impossible. The valve according to the invention combines the fluid-switching function of the main valve with the protection against backflow of the fluid in a single structural unit. Additional backflow preventers are no longer necessary. The assembly effort and the associated risk of assembly errors are reduced.

[0013] Preferably, the valve, in particular the main valve, is a self-actuated servo valve. A self-actuated servo valve enables energy-efficient switching of a fluid. The pressure of the fluid to be switched can be used to actuate the self-actuated servo valve.

[0014] According to one design embodiment, it is proposed that the valve include a pilot valve for switching the main valve. The main valve, in particular a main valve designed as a self-actuated servo valve, can be easily actuated via the pilot valve to transition between a closed and an open position. The pilot valve can be actuated via a float, a manual actuating element, and / or an electromagnet.

[0015] According to the invention, the backflow preventer is arranged between the valve inlet and the main valve. Due to the arrangement between the valve inlet and the main valve, the backflow preventer can be arranged upstream of the main valve in the flow channel along a main flow direction. The backflow preventer arranged between the valve inlet and the main valve can prevent a relative negative pressure on the valve inlet side from affecting the main valve. Opening of the main valve by a force caused by a relative negative pressure on the valve inlet side can be easily prevented by the backflow preventer. Alternatively, the backflow preventer can be arranged between the main valve and the valve outlet.

[0016] The flow channel preferably has a central flow channel section extending between the non-return valve and the main valve. The valve seat arranged in the flow channel can be located at the beginning or end of this flow channel section. When the main valve is closed, the non-return valve can shield the central flow channel section from a pressure drop on the valve inlet side. The pressure of the fluid in the central flow channel section can be kept substantially constant in the event of a pressure drop on the valve inlet side. Transmission of a relative negative pressure on the valve inlet side via the central flow channel section can be easily prevented.

[0017] According to one design embodiment, it is proposed that the closing element of the backflow preventer be prestressed toward the valve seat of the backflow preventer. Due to the prestressed closing element, the valve seat of the backflow preventer can be easily closed by the closing element in the event of a pressure drop on the valve inlet side. A trigger pressure can be set via the prestress of the closing element. As soon as the pressure of the upstream fluid falls below this trigger pressure, the backflow preventer can close. The closing element can be prestressed mechanically, hydraulically, and / or mechanically. The prestressed closing element can be actuated essentially independently of the ratio of the pressures prevailing in the flow channel upstream and downstream of the backflow preventer.The actuation of the closing element can essentially depend on the ratio of the preload of the closing element to the pressure in the flow channel section upstream of the non-return valve along the main flow direction.

[0018] It is provided that the closing element is controllable via a first control chamber and a second control chamber. A first control chamber and a second control chamber enable control based on a ratio of the conditions in the control chambers, in particular the prevailing pressures and / or acting forces. The first control chamber and the second control chamber can be arranged on different, in particular opposite, sides of the closing element. The backflow preventer can be opened or closed depending on the ratio of the forces exerted on the closing element in the first control chamber and in the second control chamber. Forces can each be exerted on the closing element in the first control chamber and in the second control chamber. Depending on the ratio of the forces exerted on the closing element in the first control chamber and in the second control chamber, the closing element can close or release the valve seat.

[0019] In one structural embodiment, the closing element separates the first control chamber and the second control chamber from one another, in particular in a pressure-tight manner. The specification of a force exerted in the first control chamber and / or in the second control chamber can be independent of the other control chamber. Due to the pressure-tight separation of the first control chamber from the second control chamber, the force exerted on the closing element in the first control chamber and / or in the second control chamber can be specified by the hydraulic and / or pneumatic pressure prevailing in the respective control chamber. By changing the force and / or the pressure in the first control chamber and / or in the second control chamber, the trigger pressure of the non-return valve can be adjusted.

[0020] It is provided that the first control chamber is part of the flow channel, in particular a flow channel section on the valve inlet side. The pressure of the fluid to be switched, particularly on the valve inlet side, can prevail in the first control chamber as part of the flow channel in a structurally simple manner. A force is exerted on the closing element in the first control chamber via the pressure of the fluid to be switched in the first control chamber and the contact surface of the closing element with the first control chamber.

[0021] In a further development of the invention, it is provided that the second control chamber can be connected to a reference pressure reservoir via a reference pressure channel, in particular to the environment external to the valve. The second control chamber can be in pressure exchange with the reference pressure reservoir via the reference pressure channel. Via the reference pressure channel, a pressure prevailing in the second control chamber can be easily adjusted to a pressure prevailing in the reference pressure reservoir. The pressure in the second control chamber can be predetermined via the reference pressure channel, in particular independently of the other pressures prevailing in the valve. A pressure prevailing in the environment external to the valve, in particular the external atmospheric pressure, can also easily prevail in the second control chamber. A force can be exerted on the closing element in the second control chamber via the pressure prevailing in the second control chamber and the contact surface of the closing element with the second control chamber.

[0022] It is possible for a preload spring to be arranged in the second control chamber, acting on the closing element of the backflow preventer. The preload spring can exert a force that preloads the closing element. The preload force of the preload spring can be exerted in addition to a force exerted on the closing element by the pressure prevailing in the second control chamber. The force exerted on the closing element by the preload spring can be greater than the force exerted on the closing element by the hydraulic and / or pneumatic pressure in the second control chamber. The closing element can be essentially preloaded by the preload spring, whereby the preload force exerted by the pressure prevailing in the second control chamber can be negligible. The trigger pressure of the backflow preventer can be specified by selecting the preload spring used.

[0023] According to one design embodiment, it is proposed that the closing element of the backflow preventer be a valve diaphragm or a plunger. A plunger can be preloaded in the direction of the valve seat in a simple manner, in particular by a preload spring. A valve diaphragm represents a structurally simple design option for a closing element for closing a valve seat. The valve diaphragm can be used in a structurally simple manner to separate, in particular pressure-tight, the first control chamber and the second control chamber. The valve diaphragm can enable actuation of the backflow preventer depending on the pressures prevailing in the first control chamber and the second control chamber. When a valve diaphragm is used as the closing element, a preload spring can also be used.

[0024] Preferably, when the valve seat is closed, the area of ​​the valve diaphragm facing the valve inlet side, opposite to the main flow direction, is larger than the area of ​​the diaphragm facing the valve outlet side, along the main flow direction. Even in the case of an overpressure on the valve outlet side, which pushes the fluid back against the main flow direction, the non-return valve can be closed or remain closed due to this area ratio if the pressure on the valve inlet side falls below a triggering pressure, without being inadvertently opened by the overpressure on the valve outlet side.

[0025] The valve seat preferably separates an upstream flow region of the backflow preventer and an outflow region of the backflow preventer arranged concentrically thereto along a main flow direction of the valve. When the backflow preventer is open, the fluid can flow from the upstream flow region via the valve seat to the outflow region of the backflow preventer. The upstream flow region of the backflow preventer and the outflow region of the backflow preventer can form parts of the flow channel, which is not blocked by the backflow preventer when it is open. The closing element of the backflow preventer can close the valve seat, thus separating the upstream flow region of the backflow preventer from the outflow region of the backflow preventer. The flow channel of the valve is thus blocked.Due to the concentric arrangement of the inflow area of ​​the check valve and the outflow area of ​​the check valve, the closing element can close the valve seat located between the inflow area and the outflow area in a structurally simple manner. For this purpose, the closing element can be movable, in particular in a straight line, toward the common center of the inflow area and the outflow area of ​​the check valve.

[0026] In a further embodiment, the inflow area is arranged radially outward relative to the outflow area. In this way, the valve seat can be approached from the radial outside along the main flow direction. A larger upstream-facing surface of the closing element, in particular a valve diaphragm, can be achieved in a structurally simple manner.

[0027] In an alternative embodiment, the inflow area is arranged radially inward relative to the outflow area. In this way, the valve seat can be subjected to radially outward flow along the main flow direction. A pre-tensioned closing element, in particular a plunger, can be easily pushed away from the valve seat if the upstream pressure is sufficiently high to open it. If the upstream fluid pressure falls below the trigger pressure, the pre-tensioned closing element can easily close automatically.

[0028] According to a further development of the invention, the backflow preventer has an actuation axis, in particular an actuation axis of the closing element, which runs parallel to an actuation axis of the main valve. The actuation axis of the backflow preventer and the actuation axis of the main valve correspond to the respective axes along which movements for opening and closing the backflow preventer or the main valve take place. The actuation axis of the backflow preventer and the actuation axis of the main valve correspond to those axes of the backflow preventer or the main valve along which the closing element or the main closing element moves to open and close the valve seat or the main valve seat. The parallel course of the actuation axis of the backflow preventer and the actuation axis of the main valve prevents actuation movements of the valve that occur transversely to one another.Due to the parallel actuating axes, the valve can be manufactured in a simple manner.

[0029] It is further advantageous if the backflow preventer has a closing direction along its actuating axis that runs opposite to a closing direction along the actuating axis of the main valve. The manufacture of the valve can be further simplified by the opposite closing directions. In particular, when the closing directions of the backflow preventer and the main valve are directed towards the inside of the valve, the valve seat and the main valve seat can be arranged on the common valve body in a structurally simple manner. By arranging the valve seat and the main valve seat on the common valve body, the manufacture of the valve can be further simplified. Static components of the valve, in particular the flow channel, the main valve seat and / or the valve seat, can be part of the valve body, in particular the multi-part valve body, in a manufacturing-technically simple manner.Movable components of the valve, in particular the closing element, the main closing element, and / or the pilot valve, can be connected to the valve body, in particular detachably. Replacement of movable components of the valve, for example, for cleaning or maintenance, can be carried out easily.

[0030] Furthermore, it is advantageous if the actuating axis of the backflow preventer is offset from the actuating axis of the main valve, in particular along a flow axis of the valve connecting the valve inlet and the valve outlet. Due to the offset arrangement of the actuating axis of the backflow preventer with respect to the actuating axis of the main valve, the backflow preventer can be arranged upstream and / or downstream of the main valve in the flow channel in a space-saving manner. The downstream area of ​​the backflow preventer along the main flow direction can be connected to the upstream area of ​​the main valve. Alternatively, the downstream area of ​​the main valve can be connected to the upstream area of ​​the backflow preventer. Along the flow axis of the valve, an essentially wave-like guidance of the flow channel can result.With the wave-like guidance of the flow channel, the flow channel can initially be guided away from the flow axis, after a reversal of the flow direction it can pass below the flow axis and after a further reversal of the flow direction it can be guided back in the direction of the flow axis.

[0031] It is further advantageous if a cover element is detachable for accessing the interior of the backflow preventer. The detachable cover element, which is particularly connectable to the valve body, allows easy access to the interior of the backflow preventer, for example, for maintenance or to replace individual components of the backflow preventer. The cover element can, in particular, form part of the outer side of the valve. In a structurally simple manner, the cover element can serve to secure a membrane-shaped closing element arranged between the valve body and the cover element.

[0032] In a method of the type mentioned above, it is proposed that the non-return valve is closed as soon as the pressure on the valve inlet side falls below a trigger pressure.

[0033] Since the check valve closes as soon as the pressure at the valve inlet falls below the trigger pressure, the flow channel is blocked regardless of the actuating position of the main valve and the pressure at the valve outlet. The check valve prevents a relative negative pressure at the valve inlet from being transmitted to the valve outlet. The fluid at the valve outlet is not sucked back toward the valve inlet by the relative negative pressure, thus preventing backflow. The fluid-switching function of the main valve is combined with the protection against backflow of the fluid in one valve.

[0034] The features described in connection with the valve according to the invention can also be applied individually or in combination to the method. The same advantages as those already described result.

[0035] It is further proposed that the triggering pressure be predetermined by the pressure in a reference pressure reservoir, in particular the atmospheric pressure outside the valve, and / or a preload spring. The triggering pressure of the backflow preventer can be predetermined in a simple manner by the pressure in a reference pressure reservoir and / or the preload spring. In particular in the case of a backflow preventer with a closing element, the pressure in a reference pressure reservoir and / or the preload spring can exert a force on the closing element in the closing direction. The fluid located in the flow channel on the valve inlet side of the backflow preventer must exert a minimum pressure in order to open the backflow preventer, so that, depending on the area of ​​the closing element exposed to this pressure, the fluid exerts a counterforce on the closing element that is equal to the force in the closing direction.This minimum pressure, which must be applied on the valve inlet side of the check valve to achieve sufficient force, corresponds to the trigger pressure of the check valve. As soon as the pressure on the valve inlet side falls below this trigger pressure, the fluid on the valve inlet side can no longer generate sufficient counterforce for the check valve to close automatically. The trigger pressure can preferably be in the range of 0.2 mbar to 0.5 bar above the pressure on the valve outlet side when the main valve is closed or atmospheric pressure.

[0036] Further details and advantages of a valve according to the invention and a method according to the invention will be explained below using the exemplary embodiments of the invention schematically illustrated in the figures. Fig. 1 three sectional views of a first embodiment of a valve according to the invention and Fig. 2 three sectional views of a second embodiment of the valve according to the invention.

[0037] Fig. 1 and Fig. 2 each show a backflow-proof valve 1 according to the invention. The valve 1 has a valve body 23 with an upstream valve inlet 2 and a downstream valve outlet 3, which are connected to one another via a flow channel 4. A main valve 5 is arranged in the flow channel 4, with which a fluid flowing between the valve inlet 2 and the valve outlet 3 can be switched. In addition to the main valve 5, a backflow preventer 13 is arranged in the flow channel 4. The backflow preventer 13 prevents the fluid from being sucked back from the valve outlet 3 to the valve inlet 2 against the main flow direction S running from the valve inlet 2 to the valve outlet 3 in the flow channel 4 when there is a relative negative pressure on the valve inlet side compared to the pressure prevailing at the valve outlet 3.

[0038] In the two exemplary embodiments shown, the backflow preventer 13 is arranged between the valve inlet 2 and the main valve 5. The backflow preventer 13, thus arranged upstream of the main valve 5 in the flow channel 4 opposite to the main flow direction S, prevents a negative pressure on the valve inlet side from being transmitted to the main valve 5 and prevents a change in the pressure conditions in the area of ​​the main valve 5 from causing the main valve 5 to open inadvertently. Nevertheless, the backflow preventer 13 can also be arranged downstream of the main valve 5 along the main flow direction S, where it protects the valve 1 against backflow of a fluid.

[0039] The example shown in Fig. 1 and Fig. The main valve 5 of valve 1 shown in Figure 2 is designed as a self-actuated servo valve. The main valve 5 has a main valve seat 6, which is arranged in the flow channel 4. In order to switch the fluid, this main valve seat 6 can be closed by a main closing element 7, so that no fluid can flow through the flow channel 4 from the valve inlet 2 to the valve outlet 3.

[0040] The main closing element 7 has a flexible membrane 7.1, via which the closing element 7 is arranged between the valve body 23, made for example from cast metal, and a cover element 24. The membrane 7.1 is so flexible that the main closing element 7 can move inside the valve 1 between an open and a closed position. Furthermore, the membrane 7.1 serves to fluid-tightly close the main valve seat 6, which is formed as part of the valve body 23. In addition to the membrane 7.1, the main closing element 7 has a support body 7.2, which provides the closing element 7 with dimensional stability, so that the main closing element 7 can close the main valve seat 6 without being deformed by the pressures prevailing in the region of the main valve 5.

[0041] A guide 7.3 is formed integrally with the support body 7.2 and projects into the flow channel section 4.3 located along the main flow direction S downstream of the main valve 5. This guide 7.3 has a star-shaped contour. As shown in Fig. 1c, the guide 7.3 can be supported with the three points of its star-shaped contour on the inner surface of the valve body 23 forming the flow channel section 4.3. Alternatively, the guide 7.3 can also have a contour with two, four, five, six or more points. Displacement of the main closing element 7 transversely to the main flow direction S relative to the main valve seat 6 can be prevented by the guide 7.3. A reproducible position of the main closing element 7 relative to the main valve seat 6 can be achieved by the guide 7.3. The guide 7.3 ensures the functional reliability of the main valve 5, since there can be no misalignment of the main closing element 7 when the main valve seat 6 is closed.

[0042] The cover element 24 of the main valve 5 is detachably connected to the valve body 23 via fastening means 25. The cover element 24 serves to fasten the main closing element 7, which is clamped between the valve body 23 and the cover element 24. In addition, the cover element 24 also accommodates the pilot closing element 11 and the electronic and / or mechanical control components used to actuate it. By loosening the cover element 24, access to the interior of the main valve 5 is possible. After loosening the cover element 24, the main closing element 7 can be easily removed from the valve body 23 for cleaning or replacement. By replacing the cover element 24, it is possible to adapt the pilot valve 9 and thus also the main valve 5 to different application requirements.For example, by replacing the cover element 24, an electromechanically actuated pilot valve 9 can be replaced by a pilot valve 9 that can be actuated in the manner of a float valve.

[0043] The function of the main valve when opening and closing will be briefly described below.

[0044] A fluid flowing toward the main closing element 7 along the main flow direction S can flow into the area formed between the main closing element 7 and the cover element 24 via a compensating channel 8 extending through the main closing element 7. In this area, which is initially sealed except for the compensating channel 8, the inflowing fluid builds up a pressure that pushes the main closing element 7 toward the main valve seat 6, thus closing it. The main valve 5 then assumes its closed state.

[0045] To open the main valve 5, the valve 1 has a pilot valve 9. This pilot valve 9 includes a pilot valve seat 10 arranged in the main closing element 7 and a pilot closing element 11 with which the pilot valve seat 10 can be closed. When the main valve 5 is closed, the pilot valve 9 is closed.

[0046] To open the main valve 5, the plunger-shaped pilot closing element 11 is lifted from the pilot valve seat 10, thereby releasing a pilot channel 12 extending through the main closing element 7. The fluid located in the area between the main closing element 7 and the cover element 24 can now flow through the pilot valve seat 10 and the pilot channel 12 into the flow channel section 4.3. Since the pilot channel 12 has a larger clear cross-section than the compensating channel 8, more fluid flows out of the area between the main closing element 7 and the cover element 24 through the pilot channel 12 than can flow in through the compensating channel 8. The pressure in the area between the main closing element 7 and the cover element 24 is therefore reduced. Since the pressure of the fluid along the main flow direction S in the flow channel section 4.2 of the fluid flowing onto the main closing element 7 remains unchanged, there is a pressure difference on the opposite sides of the main closing element 7. Due to this pressure difference, the main closing element 7 is lifted off the main valve seat 6 along its actuating axis H, which coincides with the actuating axis of the pilot valve 9, against the closing direction J.

[0047] Via the open main valve seat 6, the flow channel sections 4.2 and 4.3 are in direct communication, so that a fluid can flow from the flow channel section 4.2 via the main valve seat 6 into the flow channel section 4.3. In the area of ​​the main valve seat 6, the flow direction is reversed, since the main flow direction S in the flow channel section 4.2 runs opposite to the closing direction J of the main valve 5, while the main flow direction S in the flow channel section 4.3 runs along the closing direction J of the main valve 5.

[0048] The main valve 5, designed as a self-actuated servo valve, enables energy-saving opening and closing, since the majority of the energy required to move the main closing element 7 is provided by the fluid to be switched. Only a comparatively small amount of energy is required to actuate the pilot valve 9. The pilot closing element 11 can be designed, for example, as a float valve or an electromagnetic plunger valve.

[0049] However, if the main valve 5, which is designed as a servo valve actuated by its own medium, experiences a pressure drop on the upstream side compared to the pressure prevailing in the flow channel 4 on the downstream side of the main valve 5, this can lead to an unintentional opening of the main valve 5. In this case, the fluid located in the area between the main closing element 7 and the cover element 24 is sucked back via the compensation channel 8 due to the negative pressure in the flow channel section 4.2, which is relative to the pressure on the valve outlet side, so that a correspondingly equal negative pressure is also established in the area between the main closing element 7 and the cover element 24. Due to the higher downstream pressure in the flow channel section 4.3, a force acts on the main closing element 7 opposite to the closing direction J, which leads to an opening of the main closing element 7. Since the pressure in the flow channel section 4.3 is larger than that in the flow channel section 4.2, when the main valve 5 is opened in this way, the fluid flows back against the main flow direction S.

[0050] In order to prevent such a backflow caused by a relative negative pressure, ie a back-suction, the valve 1 according to the invention has the non-return valve 13 arranged in a captive manner. Fig. The non-return valve 13 shown in Figure 1 prevents a negative pressure on the valve inlet side from being transmitted to the main valve 5. For this purpose, the non-return valve 13 has a valve seat 14 and a closing element 15. The closing element 15 is in the Fig. 1, the valve seat 14 is designed as a valve diaphragm. The closing element 15 can be used to open and close the valve seat 14, which is formed integrally with the valve body 23 and arranged in the flow channel 4.

[0051] Similar to the main closing element 7, the closing element 15 has an elastic membrane 15.1, with which the closing element 15 is movably arranged between a cover element 22 and the valve body 23. The cover element 22 closes off the interior of the valve 1 from the outside and forms part of the outer surface of the valve 1. In order to access the interior of the valve 1 and the interior of the backflow preventer 13, the cover element 22 is connected to the valve body 23 via fastening means 25. By loosening the fastening means 25, the cover element 22 can be removed, thus enabling, for example, a replacement of the closing element 15.

[0052] Since the valve seat 14 is integrally arranged on the valve body 23, the entire backflow preventer 13 cannot be lost when the cover element 22 is removed. Since the entire backflow preventer 13 is part of the valve 1, it cannot be forgotten during assembly of the valve 1.

[0053] A support body 15.2 and a guide 15.3 with a star-shaped contour serve to provide stability and guide the closing element 15, as already described in connection with the corresponding support body 7.2 and the guide 7.3 in connection with the main valve 5.

[0054] Unlike the main closing element 7, however, the closing element 15 does not have a compensating channel 8 connecting the two opposite sides of the closing element 15. Rather, the closing element 15 separates two control chambers 16, 17 located on opposite sides of the closing element 15 in a pressure-tight manner.

[0055] A first control chamber 16 is formed by the part of a control channel section 4.1 adjacent to the closing element 15 on the valve inlet side. A second control chamber 17 is located on the side of the closing element 15 opposite the first control chamber 16 along an actuation axis R of the non-return valve 13. This second control chamber 17 is delimited by the closing element 15 and the cover element 22. Since the controlling fluid from the flow channel 4 cannot enter the second control chamber 17 through the closing element 15, this second control chamber 17 is pressure-tightly separated from the flow channel 4.

[0056] The second control chamber 17 is connected to a reference pressure reservoir 1000 via a reference pressure channel 18, which is arranged in the cover element 22. In the Fig. 1, the reference pressure reservoir 1000 is formed by the environment outside the valve. However, a different reference pressure reservoir 1000 can also be used, for example a pressure tank. The pressure in the second control chamber 17 corresponds to the atmospheric pressure of the environment outside the valve. The pressure in the second control chamber 17 is independent of the fluid pressures inside the valve 1. Due to the essentially constant atmospheric pressure exerted on the surface of the closing element 15 facing away from the valve seat 14, the closing element 15 is prestressed with a force acting in the direction of the valve seat 14. In addition to the prestressing force exerted on the closing element 15 by the hydraulic pressure in the second control chamber 17, a Fig. 1, a preload spring (not shown) may be arranged, which exerts an additional preload force on the closing element 15.

[0057] The valve seat 14 of the check valve 13 divides the flow channel 4 in the area of ​​the check valve 13 into an inflow area 20 of the check valve 13 and an outflow area 21 of the check valve 13 arranged concentrically thereto along the main flow direction S of the valve 1. The inflow area 20 is formed by the area of ​​the flow channel section 4.1 which also borders the flow element 15. In the Fig. 1, the first control chamber 16 and the inflow area 20 of the non-return valve 13 therefore coincide spatially.

[0058] The inflow region 20 forms an annular region around the valve seat 14. The outflow region 21, on the other hand, is formed by the region of the flow channel section 4.2 adjacent to the closing element 15. In this way, the inflow region 20 is also arranged at the outer outflow region 21. This arrangement of the inflow region 20, the outflow region 21, and the valve seat 14 enables easy flow of the fluid from the inflow region 20 to the outflow region 21 via the valve seat 14 when the closing element 15 is open.

[0059] The function of the backflow preventer 13 will now be described in more detail below. As long as a greater force is exerted on the closing element 15 in the first control chamber 16, in which the valve inlet-side pressure is applied, than in the second control chamber 17, the closing element 15 is pressed away from the valve seat 14 by the resulting force and the backflow preventer 13 is opened. The force exerted on the closing element 15 in the first control chamber 16 or in the second control chamber 17 results from the product of the respective prevailing pressures and the area of ​​the closing element 15 on which these pressures are exerted, ie the contact area of ​​the closing element 15 with the respective control chamber 16, 17. When using a Fig. 1, the additional preload spring 19 not shown must be added to the corresponding spring force of the force caused by the pressure in the second control chamber 17 on the closing element 15.

[0060] When the check valve 13 is open, a fluid can flow along the main flow direction S from the inflow area 20 of the check valve 13 via the valve seat 14 to the outflow area 21 of the check valve 13. The fluid can then flow into the main valve 5 via the central flow channel section 4.2 and be switched by it.

[0061] If the pressure on the valve inlet side now drops to such an extent that the force exerted on the closing element 15 in the first control chamber 16 is no longer sufficient to push the closing element 15 away from the valve seat 14, the backflow preventer 13 closes automatically. This is because the force exerted on the closing element 15 in the second control chamber 17, independent of the pressure on the valve inlet side, results in a resultant force on the closing element 15 pointing in the direction of the valve seat 14. In this way, the backflow preventer 13 prevents the fluid from being sucked back from the flow channel section 4.2 into the flow channel section 4.1 against the main flow direction S.

[0062] Since the pressure drop is not transmitted to the central flow channel section 4.2, this pressure drop does not affect the main valve 5 in the manner of a relative negative pressure. The above-described unintentional opening of the main valve 5 due to the pressure drop does not occur. Due to the closed non-return valve 13, even if the main valve 5 is intentionally opened, there is no backflow of fluid from the valve outlet 3 to the valve inlet 2.

[0063] Since, when the main valve 5 is closed, it remains in its closed position even if there is a pressure drop on the valve inlet side, a backflow of the fluid to be switched is additionally blocked.

[0064] The backflow preventer 13 closes in the manner described above as soon as the fluid pressure on the valve inlet side falls below a trigger pressure of the backflow preventer 13. The trigger pressure is predetermined by the ratio of the product of the pressure prevailing in the second control chamber 17 and the area of ​​the closing element 15 facing the second control chamber 17, optionally plus the preload force of a preload spring 19, to the area of ​​the closing element 15 facing the first control chamber 16. The trigger pressure can be set by adjusting the pressure in the reference pressure reservoir 1000, the preload spring 19 used and / or the area ratio of the surfaces of the closing element 15 facing the first control chamber 16 or the second control chamber 17. The trigger pressure corresponds to the pressure that must be present in the first control chamber 16 so that the force acting on the closing element 15 in the closing direction K is balanced.

[0065] As in the Fig. 1a along the flow axis A connecting the valve inlet 2 to the valve outlet 3, when the non-return valve 13 is open, the flow direction is also reversed in the region of the valve seat 14 from the main flow direction S running counter to the closing direction K in the flow channel section 4.1 to the main flow direction S running along the closing direction K in the flow channel section 4.2.

[0066] Compared to the flow axis A, the flow channel 4 has a wave-like course. In the area of ​​the valve inlet 2, the main flow direction S along the flow channel 4 initially runs essentially along the flow axis A. In the flow channel section 4.1, the main flow direction S is diverted away from the flow axis A, essentially at a right angle, towards the backflow preventer 13. In the area of ​​the valve seat 14, the above-described reversal of flow direction occurs from the flow channel section 4.1 to the flow channel section 4.2. The flow channel section 4.2 runs beyond the flow axis A to the side of the valve 1 opposite the backflow preventer 13. In the area of ​​the main valve seat 6, there is a further reversal of flow direction from the flow channel section 4.2 to the flow channel section 4.3.3, the main flow direction S is then again guided essentially parallel to the flow axis A towards the flow channel 4, which runs essentially parallel to the flow axis A, in the region of the valve outlet 3.

[0067] In Fig. 1b is a transverse to the Fig. 1a shows a longitudinal section through the valve 1 along the flow axis A with a view towards the non-return valve 13. Fig. 1c shows the other half of the section with a view towards the main valve 5.

[0068] In Fig. In Figure 1b, the inflow area 20 can be seen in detail, as can the entire outflow area 21 of the backflow preventer 13. Furthermore, the guide 15.3 of the closing element 15, which has a trident star contour, can be seen in the flow channel section 4.2. As can be seen, the inflow area 20 surrounds the outflow area 21 in a ring shape.

[0069] It can also be seen that the surface of the closing element 15 facing the valve inlet side in the inflow area 20 against the main flow direction S is larger than the surface of the closing element 15 facing the valve outlet side in the outflow area 21 along the main flow direction S.

[0070] In Fig. 1c shows that the fluid flow in the area of ​​the main valve 5 essentially corresponds to the fluid flow in the area of ​​the backflow preventer 13, although the actuation axis H of the main valve 5 is offset from the actuation axis R of the backflow preventer 13 along the flow axis A. In this way, the outflow area 21 of the backflow preventer 13 is connected to a corresponding inflow area of ​​the main valve 5 via the flow channel section 4.2 in a space-saving manner. Both the closing element 15 of the backflow preventer 13 and the main closing element 7 of the main valve 5 are subjected to flow radially outwardly along the main flow direction S, so that when the valve seat 14 or the main valve seat 6 is open, the fluid flows radially inwardly through the valve seat 14 or the main valve seat 6.

[0071] In Fig. 2 shows a second embodiment of the valve 1 according to the invention. Since the structure of the valve 1 and the functioning of the individual parts of the valve 1 as well as of the entire valve 1 are similar to the Fig. 1, only the differences between this second embodiment and the first embodiment will be discussed below. Otherwise, reference is made to the above descriptions of the individual parts of the valve 1, which also apply to the valve shown in Fig. The second embodiment of the valve 1 shown in Figure 2 applies accordingly.

[0072] The locking element 15 of the Fig. The backflow preventer 13 shown in Figure 2 is designed in the manner of a direct-acting plunger. This closing element 15 has an elastic closing means 15.4, with which the valve seat 14 of the backflow preventer 13 can be closed. The closing means 15.4 is connected to a piston 15.5 of the closing element 15 via a mushroom-shaped connecting element 15.6. The piston 15.5 of the closing element 15 has a stepped diameter reduction 15.7 at its end region opposite the closing means 15.4. A preload spring 19 engages this diameter reduction 15.7, which preloads the closing element 15 toward the valve seat 14 of the backflow preventer 13.

[0073] The end of the biasing spring 19 opposite the closing element 15 is arranged on the inside of the valve on the cover element 22. The piston 15.5 of the closing element 15 and the biasing spring 19 are arranged in a tubular region of the cover element 22. The region between the closing element 15 and the cover element 22 forms a second control chamber 17, via which the closing element 15 can be controlled. The biasing spring 19 is arranged in this second control chamber 17.

[0074] Unlike in the first embodiment, the second control chamber 17 is in Fig. 2 is not pressure-tightly separated from the first control chamber 16. Rather, a fluid can enter the second control chamber 17 from the first control chamber 16 when the backflow preventer 13 is open. Nevertheless, the second control chamber 17 can be pressure-tightly separated from the first control chamber 16 by an additional seal between the piston 15.5 and the cover element 22, even when the backflow preventer 13 is open.

[0075] Also in Fig. The second embodiment shown in Figure 2 has an inflow region 20 of the backflow preventer 13 and an outflow region 21 of the backflow preventer 13 arranged concentrically thereto, which are separated by the valve seat 14 along the main flow direction S. The inflow region 20 is in the embodiment of Fig. 2, however, arranged radially inward of the inflow area 20. Due to the inwardly disposed inflow area 20, when the non-return valve 13 is closed, the end face of the plunger-shaped closing element 15 used to close the valve seat 14 is subjected to flow essentially centrally to the actuating axis R. The pressure of the valve inlet-side fluid prevailing in the area of ​​the flow channel section 4.1 forming a first control chamber 16 counteracts the preload force exerted on the closing element 15 by the preload spring 19.

[0076] In Fig. 2, the trigger pressure is determined primarily by the spring force of the preload spring 19 exerted on the closing element 15 and the force exerted by the fluid pressure in the second control chamber 17 and in the outflow region 21 in the direction of the valve seat 14 in relation to the surface of the closing element 15 in contact with the first control chamber 16.

[0077] Even in the case of an overpressure on the valve outlet side, which pushes the fluid back against the main flow direction S when the main valve 5 is open, the backflow preventer 13 can be closed or remain closed due to this force-to-area ratio when the trigger pressure on the valve inlet side falls below the trigger pressure, without being inadvertently opened by the overpressure on the valve outlet side. This is because an overpressure on the valve outlet side, which is transmitted to the outflow area 21, presses the closing element 15 more firmly against the valve seat 14.

[0078] The fluid pressure in the second control chamber 17 and in the outflow area 21 can make the significant contribution to the release pressure. A preload spring 19 with a low spring constant can be used. The preload spring 19 should be designed to be sufficiently strong that the closing element 15 is held tightly against the valve seat 14 even in an overhead installation, where the weight of the closing element 15 acts against the closing direction K, provided no other forces or pressures act on the closing element 15.

[0079] In the area of ​​the valve seat 14, the outflow area 21 surrounds the inflow area 20 essentially in a ring shape. However, in contrast to the first embodiment, the flow channel section 4.2 connecting the outflow area 21 with the main valve 5 is formed in two parts, as shown in the Fig. 2b and Fig. 2c can be seen.

[0080] As already mentioned in Fig. 1 represents the Fig. 2b a transverse to the Fig. 2a shows a longitudinal section along the flow axis A with a view towards the non-return valve 13. In Fig. 2c shows the corresponding other section half looking towards the main valve 5.

[0081] In Fig. 2b and Fig. Figure 2c shows the two-part flow channel section 4.2. The two main ring-segment-like parts of the flow channel section 4.2 surround the flow channel section 4.1 on essentially opposite sides. In the area of ​​the main closing element 7, the two parts of the middle flow channel section 4.2 merge to direct the flow radially outward toward the main valve seat 6.

[0082] Although the flow channel section 4.2 is divided into two parts, the flow channel 4 of the Fig. 2 shown valve 1 is essentially wave-shaped relative to the flow axis A.

[0083] Since the release pressure in the valve 1 is essentially determined by a preload spring 19, the release pressure in the Fig. 2 can be easily adjusted by selecting the preload spring 19. The provision of a reference pressure reservoir 1000 and the maintenance of the pressure prevailing in this reference pressure reservoir 1000 can be dispensed with in a structurally simple manner.

[0084] To enable the valve 1 to be installed in a line section, the valve inlet 2 and the valve outlet 3 have fastening means, which can be designed, for example, in the form of an external thread, an internal thread, and / or a hose nozzle. The fastening means of the valve inlet 2 and the valve outlet 3 can differ from one another.

[0085] The valve 1 described above and the described method for operating such a valve 1 make it possible to achieve a high level of safety against backflow while at the same time requiring little assembly effort and reducing the risk of assembly errors. Reference symbol: 1 valve 2 valve inlet 3 Valve outlet 4 flow channel 4.1 Flow channel section 4.2 Flow channel section 4.3 Flow channel section 5 Main valve 6 Main valve seat 7 Main locking element 7.1 Membrane 7.2 Support body 7.3 Leadership 8 compensation channel 9 Pilot valve 10 Pilot valve seat 11 Pilot locking element 12 pilot channel 13 backflow preventers 14 Valve seat 15 locking element 15.1 Membrane 15.2 Support body 15.3 Leadership 15.4 Locking devices 15.5 pistons 15.6 Connecting element 15.7 Diameter reduction 16 First control room 17 Second control room 18 Reference pressure channel 19 Preload spring 20 Inflow area 21 Outflow area 22 Cover element 23 Valve body 24 Cover element 1000 reference pressure reservoir A flow axis H Actuating axis J Closing direction K Closing direction R Actuating axis S Main flow direction

Claims

[1] Valve with a valve body (23), a main valve (5) and a backflow preventer (13), wherein the valve body (23) has an upstream valve inlet (2), a downstream valve outlet (3) and a flow channel (4) for connecting the valve inlet (2) to the valve outlet (3), wherein the main valve (5) and the backflow preventer (13) are arranged in the flow channel (4), wherein the backflow preventer (13) has a valve seat (14) and a closing element (15) for opening and closing the valve seat (14), wherein the valve seat (14) is arranged in one piece on the valve body (23) and wherein the closing element (15) is controllable via a first control chamber (16) and a second control chamber (17), wherein the first control chamber (16) is part of the flow channel (4), characterized by that the non-return valve (13) is arranged between the valve inlet (2) and the main valve (5). [2] Valve according to claim 1, characterized bythat the closing element (15) of the backflow preventer (13) is prestressed in the direction of the valve seat (14) of the backflow preventer (13). [3] Valve according to one of the preceding claims, characterized by that the closing element (15) separates the first control chamber (16) and the second control chamber (17), in particular in a pressure-tight manner. [4] Valve according to one of the preceding claims, characterized by that the first control chamber (16) is part of a valve inlet-side flow channel section (4.1). [5] Valve according to one of the preceding claims, characterized by that the second control chamber (17) can be connected to a reference pressure reservoir (1000) via a reference pressure channel (18), in particular to the environment outside the valve. [6] Valve according to one of the preceding claims, characterized bythat a pre-tensioning spring (19) acting on the closing element (15) of the non-return valve (13) is arranged in the second control chamber (17). [7] Valve according to one of the preceding claims, characterized by that the closing element (15) of the non-return valve (13) is a valve membrane or a plunger. [8] Valve according to one of the preceding claims, characterized by that the valve seat (14) separates an inflow region (20) of the backflow preventer (13) and an outflow region (21) of the backflow preventer (13) arranged concentrically thereto along a main flow direction (S) of the valve (1). [9] Valve according to claim 8, characterized by that the inflow area (20) is arranged radially outwardly to the outflow area (21). [10] Valve according to claim 8, characterized by that the inflow area (20) is arranged radially inward of the outflow area (21). [11] Valve according to one of the preceding claims, characterized by that the backflow preventer (13) has an actuating axis (R), in particular an actuating axis (R) of the closing element (15), which runs parallel to an actuating axis (H) of the main valve (5). [12] Valve according to claim 11, characterized by that the non-return valve (13) has a closing direction (K) along its actuating axis (R) which runs opposite to a closing direction (J) along the actuating axis (H) of the main valve (5). [13] Valve according to one of claims 11 or 12, characterized by that the actuating axis (R) of the non-return valve (13) is offset from the actuating axis (H) of the main valve (5), in particular along a flow axis (A) of the valve (1) connecting the valve inlet (2) and the valve outlet (3). [14] Valve according to one of the preceding claims, characterized bythat a cover element (22) is detachable for accessing the interior of the backflow preventer (13). [15] Valve according to one of the preceding claims, characterized by that it is a servo valve. [16] Method for operating a valve (1) according to one of claims 1 to 15, characterized by that the non-return valve (13) is closed as soon as the pressure on the valve inlet side falls below a trigger pressure. [17] Method according to claim 16, characterized by that the trigger pressure is predetermined by the pressure in a reference pressure reservoir (1000), in particular the atmospheric pressure outside the valve, and / or a preload spring (19).

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