Powder delivery chamber for a dense phase powder pump and dense phase powder pump comprising a powder delivery chamber

Abstract

The invention relates to a powder delivery chamber (2, 2') for a dense phase powder pump (1) for delivering powder, in particular coating powder, wherein the powder delivery chamber (2, 2') has an end region, via which the powder delivery chamber (2, 2') is fluidically connected or can be fluidically connected to a powder line (9), wherein the end region of the powder delivery chamber (2, 2') is configured as a transition region (8) and is designed to reduce the effective flow cross section of the powder delivery chamber (2, 2') to the effective flow cross section of the powder line (9) and / or to the effective flow cross section of a valve (6, 7), in particular a pinch valve, arranged between the powder delivery chamber (2, 2') and the powder line (9). In particular, according to the invention, a cleaning system is associated with the end region, with which cleaning system cleaning air in the form of compressed air can be supplied to the end region (as required, in particular) in order to keep the end region free of powder deposits or in order to remove powder deposits in the end region.

Description

Technical Field

[0001] 1. The present invention relates to a powder conveying chamber for a dense phase powder pump.

[0002] 2. Therefore, the present invention relates more specifically to a powder delivery chamber of a dense-phase powder pump for conveying powders, particularly coating powders, wherein the powder delivery chamber includes an end region through which the powder delivery chamber is fluidly connected, as needed, or fluidly connectable to a powder line via a valve, particularly a pinch valve. The end region of the powder delivery chamber is thus configured as a transition region and is designed to reduce the effective flow cross-sectional area of ​​the powder delivery chamber to the effective flow cross-sectional area of ​​the valve in the open state, or respectively, to the effective flow cross-sectional area of ​​the powder line.

[0003] 3. The present invention also relates to a dense phase powder pump comprising at least one such powder delivery chamber.

[0004] 4. The dense phase powder pump of the present invention is particularly used for conveying coating powder from a first powder reservoir to a second powder reservoir arranged downstream of the dense phase powder pump, or to a powder spray gun arranged downstream of the dense phase powder pump, or to a similar device for spraying coating powder. Background Technology

[0005] 5. The principle of the above-mentioned type of dense phase powder pump is known from the prior art.

[0006] 6. For example, EP 1 551 558 A1 relates to a dense phase powder pump having a first powder delivery chamber and a second powder delivery chamber arranged parallel to the first powder delivery chamber. The two powder delivery chambers of this known prior art dense phase powder pump are restricted on both the suction and delivery sides by mechanically operated pinch valve arrangements.

[0007] 7. Accordingly, a powder hose is specifically provided that connects to the corresponding powder delivery chamber of the dense phase powder pump in the suction or delivery region of the pump, such that it is deformable by mechanical force, thereby allowing the hose cross-section to be squeezed or opened as needed. The two parallel powder delivery chambers operate in alternating phases, meaning that one of the two powder delivery chambers draws in coating powder through the powder inlet of the dense phase powder pump, while the other of the two powder delivery chambers dispenses a portion of the coating powder previously drawn into the powder delivery chamber through the powder outlet of the dense phase powder pump.

[0008] 8. Dense phase powder pumps having multiple, particularly two powder delivery chambers connected in parallel, are also known from WO 2005 / 005060 A2 (US 2006 / 0193704 A1), DE 199 59 473 A1 (US 2001 / 0003568 A1) and EP 1 752 399 A1.

[0009] 9. Dense-phase powder pumps are known from DE 196 11 533 B4, WO 2004 / 087331 A1 and EP 1 566 352 A2 to deliver coating powder to suitable devices for spraying coating powder, for example, in particular powder spray guns.

[0010] 10. Before the use of dense-phase powder pumps for conveying coating powders was known, powder pumps designed as ejectors were used, and these are still used today for coating powder conveying. However, unlike dense-phase powder pumps, powder pumps designed as ejectors (also known as "dilute-phase powder pumps") have the following disadvantages: these powder pumps can typically only convey a relatively small amount of coating powder per unit time.

[0011] 11. To date, dense phase powder pumps have been widely used in practice, especially for applications that require the delivery of relatively large amounts of coating powder per unit time.

[0012] 12. However, in practical applications it has been shown that, for example, dense-phase powder pumps known from EP 1 551 558 A1 have problems with continuous powder delivery, especially with certain types of powder delivery, or require relatively frequent maintenance. Summary of the Invention

[0013] 13. The present invention aims to solve the task of easily avoiding or at least reducing powder accumulation and powder blockage during the powder conveying mode of a dense phase powder pump of the type described above, particularly at the powder inlet side of the powder conveying chamber and / or at the powder outlet side of the powder conveying chamber of the dense phase powder pump. This is also particularly applicable to powder types that tend to agglomerate and / or adhere during conveying.

[0014] 14. In particular, the above-mentioned type of dense phase powder pump will be further developed in a less maintenance-intensive manner, thereby ensuring continuous and uniform powder delivery, especially regardless of the powder type.

[0015] 15. Therefore, the present invention particularly relates to a powder delivery chamber of a dense-phase powder pump for conveying powders, especially coating powders, wherein the powder delivery chamber includes an end region through which the powder delivery chamber is fluidly connected, or fluidly connectable to, a powder line as needed, via a valve, particularly a pinch valve. The end region of the powder delivery chamber is thus configured as a transition region and is designed to reduce the effective flow cross-sectional area of ​​the powder delivery chamber to the effective flow cross-sectional area of ​​the valve in the open state, or respectively to the effective flow cross-sectional area of ​​the powder line.

[0016] 16. The present invention particularly provides a cleaning system that is allocated to the end region of a powder conveying chamber, and in particular cleaning air in the form of compressed air can be supplied to the end region, especially when necessary, so as to keep the end region free of powder deposits or remove powder deposits at the end region.

[0017] 17. Providing such an end-area cleaning system can effectively prevent destructive and therefore unwanted powder buildup (powder agglomeration) and potentially associated powder blockage at the powder inlet and / or powder outlet of the powder delivery chamber during the powder delivery mode of a dense phase powder pump.

[0018] 18. Specifically, during the output phase of the dense phase powder pump, especially at the end of the output phase, or during the cleaning cycle of the dense phase powder pump, the cleaning system can help clean the corresponding end areas, and especially the inlet and outlet areas of the powder conveying chamber.

[0019] 19. For example, when purge air is introduced into the end region of the powder conveying chamber in addition to the conveying compressed air introduced into the powder conveying chamber (by applying appropriate positive pressure to the powder conveying chamber) during the output cycle of the dense phase powder pump, effective flushing of the end region of the powder conveying chamber is achieved. This optimally prevents or at least reduces powder agglomeration, thereby preventing or at least reducing the resulting blockage.

[0020] 20. Various methods can be envisioned when performing end-area cleaning. According to a preferred embodiment, certain areas of the end region of the powder delivery chamber (which are particularly at least partially tapered) are designed to correspondingly define filters for said end regions. The filters are permeable to air but impermeable to coating powder and are surrounded by an annular chamber to which compressed air can be connected as needed.

[0021] 21. Embodiments of the solution of the present invention particularly specify the allocation of a control device to a cleaning system designed to fluidly connect at least one cleaning air outlet of the end region of the powder conveying chamber to a compressed air supply line or compressed air source when needed. The control device is particularly designed to fluidly connect said at least one cleaning air outlet of the end region of the powder conveying chamber to a compressed air supply line or compressed air source during cleaning operations.

[0022] 22. As an alternative or supplement to this, the control device is designed to fluidly connect at least one purging air outlet of the end region of the powder conveying chamber to a compressed air supply line or compressed air source during the powder output cycle of the powder conveying chamber.

[0023] 23. According to a further improvement of the latter embodiment, the control device is specified to adjust, in particular, the volume of compressed air supplied to the at least one cleaning air outlet in the end region of the powder conveying chamber per unit time, especially according to the operating state and / or operating cycle of the powder conveying chamber. Thus, it is meaningful for the control device to supply a larger volume of compressed air per unit time to the at least one cleaning air outlet in the end region of the powder conveying chamber during cleaning operations than the volume of compressed air supplied to the at least one cleaning air outlet per unit time during powder output mode.

[0024] 24. Embodiments of the powder conveying chamber of the present invention specify that the end region of the powder conveying chamber is fluidly connected to or can be fluidly connected to a powder pipeline via a valve, particularly a pinch valve, wherein the valve, particularly the pinch valve, presents an effective flow cross-sectional area in its open state. Thus, the end region of the powder conveying chamber is designed to reduce the flow cross-sectional area of ​​the powder conveying chamber to the effective flow cross-sectional area of ​​the valve, particularly the pinch valve, in its open state.

[0025] 25. Similar to the end region of the powder conveying chamber, the powder conveying chamber itself or the main region of the powder conveying chamber each includes at least one air exchange opening, which is designed and formed separately, in particular, from the purge air outlet of the end region, for alternate fluid connection to a vacuum line or vacuum source or fluid connection to a compressed air supply line or compressed air source, to draw powder into the powder conveying chamber or pneumatically discharge a portion of powder that has been previously drawn into the powder conveying chamber.

[0026] 26. According to an embodiment of the invention, a powder delivery chamber has a first end region and a second end region disposed opposite thereto, wherein the powder delivery chamber is fluidly connected to or is capable of being fluidly connected to a first powder line via the first end region, and is fluidly connected to or is capable of being fluidly connected to a second powder line via the second end region. The first end region and / or the second end region of the powder delivery chamber are thus respectively implemented as transition regions and are designed to reduce the effective flow cross-sectional area of ​​the powder delivery chamber to the effective flow cross-sectional area of ​​the corresponding powder line. This further improvement specifically specifies that both the first end region and the second end region are provided with a purging system, through which purging air in the form of compressed air can be supplied, especially when necessary, to the respective end regions to keep the respective end regions free of powder deposits or to remove powder deposits at the end regions.

[0027] 27. Preferably, the diameter decreases at both end regions of the powder conveying chamber, resulting in a smaller cross-sectional area and thus turbulence due to the change in material velocity, but also increased impact, which ultimately leads to powder deposition on the conical surface. These phenomena are increasingly observed at the inlet region of the powder conveying chamber. To counteract this, the end regions of the powder conveying chamber are provided with corresponding cleaning systems. The end regions of the powder conveying chamber can in particular be designed to be separate; that is, at least partially composed of a porous material and replaceable end components that can be pressurized with compressed air, so that the conical inner wall surface of the end components is flushed by air.

[0028] 28. According to an embodiment of the invention, the cleaning system has a filter element that is permeable to air but impermeable to powder, and particularly has at least some tapered, tapering regions. The tapered filter element defines the extent of the powder delivery chamber at its end region. The filter element is surrounded by an annular chamber formed by a filter housing, wherein compressed air can be connected to the annular chamber when needed.

[0029] 29. The filter element is preferably releasably connected, or releasably connected, to the end region of the powder conveying chamber, particularly the cylindrical body region, via its larger diameter end region. Alternatively, the filter element is preferably releasably connected, or releasably connected, to the end region of the powder pipeline via its smaller diameter end region, or releasably connected, or releasably connected, to a valve, particularly a pinch valve, disposed between the powder conveying chamber and the powder conveying pipeline.

[0030] 30. The present invention also relates to a cleaning system for the end region of a powder conveying chamber, particularly a powder conveying chamber of the type described above. The cleaning system is designed to supply cleaning air, in the form of compressed air, to the end region of the powder conveying chamber, especially when necessary, in order to keep the end region free of powder deposits or to remove powder deposits at the end region.

[0031] 31. The present invention also relates to a dense-phase powder pump for conveying coating powder from a first powder reservoir to a downstream second powder reservoir or to a downstream powder spray gun or similar device for spraying coating powder. The dense-phase powder pump has at least one powder delivery chamber of the type described above, said at least one powder delivery chamber being fluidly connected or potentially fluidly connected to the first powder reservoir via a powder inlet, and fluidly connected or potentially fluidly connected to the second powder reservoir or fluidly connected or potentially fluidly connected to the powder spray gun or similar device for spraying powder via a powder outlet. A corresponding inlet valve or outlet valve is provided at the powder inlet and at the powder outlet of the dense-phase powder pump.

[0032] 32. A preferred embodiment of the dense phase powder pump of the present invention particularly specifies that the powder inlet valve is designed to be appropriately larger in size than the powder outlet valve. This embodiment is based on the understanding that the powder inlet valve of the dense phase powder pump is crucial for adjusting the flow of powder that can actually be delivered by the dense phase powder pump per unit time. Embodiments of the dense phase powder pump of the present invention, to a certain extent, specify that the at least one powder inlet valve, in its open state, presents an effective flow cross-sectional area larger than that of the powder outlet valve in its open state.

[0033] 33. As an alternative, embodiments of the dense-phase powder pump of the present invention specify that the at least one powder inlet valve and the at least one powder outlet valve have at least substantially the same effective flow cross-sectional area in their respective open states. The advantage of this embodiment is that valves with identical structures can be used for both the at least one powder inlet valve and the at least one powder outlet valve, which is associated with advantages in maintenance and spare parts storage.

[0034] 34. According to the invention, a dense-phase powder pump has a powder inlet connected to or connectable to a (upstream) first powder reservoir, and a powder outlet connected to or connectable to a (downstream) second powder reservoir or a (downstream) powder spray gun or similar device for spraying powder. Thus, the powder inlet of the dense-phase powder pump can be arranged at a first end region of the pump, and the powder outlet can be arranged at the opposite second end region, wherein the at least one powder delivery chamber of the dense-phase powder pump is arranged between the powder inlet and the powder outlet.

[0035] 35. In an advantageous embodiment of the invention, the at least one powder delivery chamber of the dense phase powder pump of the invention has a powder inlet and a powder outlet, the powder inlet having at least one powder inlet valve located in a first end region, and the powder outlet having at least one powder outlet valve located in a opposite second end region. The powder inlet of the at least one powder delivery chamber is fluidly connected to, or is capable of being fluidly connected to, the powder inlet of the dense phase powder pump via the at least one powder inlet valve. Conversely, the powder outlet of the at least one powder delivery chamber of the dense phase powder pump is fluidly connected to, or is capable of being fluidly connected to, the powder outlet of the dense phase powder pump via the at least one powder outlet valve.

[0036] 36. According to another aspect of the invention, a dense-phase powder pump has a powder inlet connected to or connectable to a first powder reservoir and a powder outlet connected to or connectable to a second powder reservoir or connected to or connectable to a powder spray gun or a similar device for spraying powder, wherein the at least one powder delivery chamber of the dense-phase powder pump of the invention has a powder channel at one end region, which serves as both a powder inlet and a powder outlet of the at least one powder delivery chamber. According to this aspect of the invention, it is advantageous that the powder channel of the at least one powder delivery chamber is fluidly connected to or fluidly connectable to the powder inlet of the dense-phase powder pump via the at least one powder inlet valve, and thus the powder channel of the at least one powder delivery chamber is fluidly connected to or fluidly connectable to the powder outlet of the dense-phase powder pump via the at least one powder outlet valve.

[0037] 37. According to a preferred embodiment, the dense-phase powder pump further includes a distributor to fluidly connect the powder passage of the powder delivery chamber to a powder inlet valve on one side and to a powder outlet valve on the other side. It is particularly conceivable to use a Y-shaped element as the distributor. However, other embodiments are of course conceivable in this respect.

[0038] 38. In a preferred embodiment of the solution of the present invention, a control device is also provided, which is designed to alternately control the at least one powder inlet valve and / or the at least one powder outlet valve of the dense phase powder pump. The control device is preferably also designed to alternately apply positive and negative pressure in the at least one powder delivery chamber of the dense phase powder pump.

[0039] 39. The at least one powder delivery chamber of the dense phase powder pump is preferably provided with a gas conduit, through which the respective powder delivery chamber can be alternately connected to a vacuum line or vacuum source for drawing coating powder into the powder delivery chamber through an open powder inlet valve when the powder outlet valve is closed, or connected to a compressed air line or compressed air source for pneumatically discharging a portion of the powder present in the powder delivery chamber through an open powder outlet valve when the powder inlet valve is closed. The control device is thus designed to alternately switch one powder delivery chamber between drawing in and discharging.

[0040] 40. In an advantageous embodiment of the dense-phase powder pump according to the invention, the aforementioned gas conduit has an air intake opening and a compressed air opening in the circumferential wall of the housing of the powder delivery chamber, wherein, preferably, a microporous filter element, preferably in the form of a filter tube, is also provided, forming the circumferential wall of the powder delivery chamber over at least a portion of its length or preferably its entire length and separating the powder delivery chamber from the annular chamber. The annular chamber is formed between the outer periphery of the filter element, preferably designed as a filter tube, and the inner periphery of the circumferential wall of the housing, and surrounds the filter element, preferably designed as a filter tube. The filter element, preferably designed as a filter tube, is permeable to air but impermeable to coated powder due to its small pore size. It is preferably composed of a sintered material.

[0041] 41. The at least one powder inlet valve and the at least one powder outlet valve of the dense phase powder pump of the present invention are preferably each designed as pinch valves, especially of the type having a flexible resilient hose as the valve passage, so that compressed air can be actuated to squeeze the flexible resilient hose in the pressure chamber surrounding the hose together in order to close the respective valve.

[0042] 42. In this case, it is particularly advantageous that the at least one powder inlet valve designed as a pinch valve and the at least one powder outlet valve designed as a pinch valve each include a pinch valve housing and a resiliently deformable valve element having a powder inlet and a powder outlet, the resiliently deformable valve element preferably being in the form of a hose section. Thus, the valve element should be arranged particularly inside the pinch valve housing so that the powder inlet of the pinch valve can be in fluid communication with the powder outlet of the pinch valve through the valve element formed as a hose section.

[0043] 43. Consequently, it is advantageous that the pinch valve housing includes at least one connector for supplying compressed air (actuating compressed air) as needed into the space formed between the inner wall of the pinch valve housing and a valve element disposed within the pinch valve housing. When the actuating compressed air is supplied, an overpressure is created in the space between the inner wall of the pinch valve housing and the valve element, resulting in the valve element being radially compressed and the pinch valve closing. When the pressure in the pinch valve housing is subsequently released, the valve element returns to its initial state, such that fluid communication exists between the powder inlet and outlet of the pinch valve via the valve element.

[0044] 44. According to one aspect of the invention, it is further specified that during the suction phase of the powder conveying chamber, a negative pressure is applied to the powder conveying chamber as early as simultaneously with or preferably after a specific lag time following the control signal to open the powder inlet valve arranged at the powder inlet of the powder conveying chamber, such that the negative pressure in the powder conveying chamber begins to build up as early as the opening of the powder inlet valve; however, preferably, it begins to build up after the aforementioned predetermined lag time following the opening of the powder inlet valve. For a conveying cycle (= dense phase powder pump cycle) of approximately 200 ms in the conveying chamber, the predetermined lag time is preferably in the range of 0 ms and 50 ms. However, this example does not preclude the use of other lag times and cycle times for the dense phase powder pump.

[0045] 45. During the suction phase of the dense phase powder pump, a negative pressure is applied to the powder delivery chamber only after the powder inlet valve has opened or at the earliest simultaneously with the opening of the powder inlet valve, so that the advantageous embodiment of the solution of the present invention can achieve a negative pressure in the powder delivery chamber that is less resistant to the opening movement of the powder inlet valve than known solutions of the prior art and designed as multi-chamber dense phase powder pumps, especially when the powder inlet valve is designed as a pinch valve.

[0046] 46. ​​To shorten the response time of the dense-phase powder pump of the present invention and thus increase its delivery frequency, it is preferably specified that, in addition to or as an alternative to the measures described above, the powder inlet valve located at the powder inlet of the powder delivery chamber and the powder outlet valve located at the powder outlet of the powder transfer chamber are each designed as pneumatically actuated pinch valves. A corresponding control valve that supplies actuating compressed air to the pinch valves in a coordinated manner is used to activate the pinch valves.

[0047] 47. A preferred embodiment of the dense phase powder pump of the present invention specifies that the length of the pneumatic control line leading to the pinch valve is minimized as much as possible in order to ensure that the response lag time is minimized when the corresponding pinch valve is actuated, i.e., when actuation compressed air is supplied, or when negative pressure is applied, or when the corresponding pinch valve housing is vented.

[0048] 48. To this end, in a preferred embodiment of the dense phase powder pump of the present invention, a material block preferably composed of multiple modules is specified, for example, the at least one powder delivery chamber of the dense phase powder pump is formed in the material block, or the at least one powder delivery chamber of the dense phase powder pump is arranged on the material block, wherein the powder inlet valve and powder outlet valve of the at least one powder delivery chamber of the dense phase powder pump are also advantageously arranged on the material block. In particular, the corresponding control valves (each control valve is preferably designed as pinch valves) for pneumatically actuating the powder inlet valve and powder outlet valve are thereby directly fluidly connected to the powder inlet valve or powder outlet valve via a compressed air passage formed in the material block, so as to ensure that actuating air is supplied to and removed from the powder inlet valve / powder outlet valve formed as pinch valves.

[0049] 49. In this case, it is further advantageous that all control valves are arranged on the material block and are fluidly connected directly to the powder delivery chamber through channels formed in the material block. All control valves are fluidly connected to the at least one powder delivery chamber of the dense phase powder pump of the present invention for supplying delivery compressed air (during the dispensing phase of the dense phase powder pump) and supplying vacuum (during the suction phase of the dense phase powder pump).

[0050] 50. These measures enable the pneumatic control line to the pinch valve and the air line to the at least one powder conveying chamber to be shortened as much as possible, so as to ensure that the response lag time is minimized when the corresponding pinch valve is actuated, i.e. when actuating compressed air is supplied, or when negative pressure is applied, or when the corresponding pinch valve housing is vented.

[0051] 51. As previously stated, by ensuring that during the suction phase of the dense phase powder pump, i.e., when a negative pressure is applied in the powder delivery chamber (which begins as early as the opening of the powder inlet valve arranged at the powder inlet of the powder delivery chamber), the response time of the dense phase powder pump of the present invention can be shortened, and thus the delivery frequency can be increased. Alternatively or supplementing this, the pump frequency can be increased by maximally shortening the passage provided for pneumatically actuating the powder inlet valve designed as a pinch valve or the powder outlet valve designed as a pinch valve, to supply actuating compressed air to or remove actuating compressed air from the pinch valve, respectively.

[0052] 52. Another advantage is that the path lengths of the plurality of channels or passages used to supply the compressed air to the at least one powder conveying chamber are shortened, or the path lengths of the plurality of channels or passages used to apply a vacuum in the powder conveying chamber are shortened. This reduces response hysteresis time when the powder inlet valve or powder outlet valve is actuated, and when a vacuum is applied in the at least one powder conveying chamber during the suction phase or when a positive pressure is applied in the at least one powder conveying chamber during the distribution phase.

[0053] 53. Therefore, increasing the delivery frequency of the dense phase powder pump ensures sufficient uniformity of the powder flow distributed at the powder outlet of the dense phase powder pump.

[0054] 54. To further increase the uniformity of the powder flow at the powder outlet of the dense phase powder pump, and especially to prevent destructive pulsations in the powder flow downstream of the powder outlet of the dense phase powder pump, a preferred embodiment of the solution of the present invention uses an auxiliary compressed air inlet device in addition to or as a supplement to the measures described above. This auxiliary compressed air inlet device is discharged into the powder path at least at at least one point between the powder outlet valve assigned to the at least one powder delivery chamber and the powder outlet of the dense phase powder pump, or preferably immediately downstream of the powder outlet of the dense phase powder pump, and is used to supply auxiliary compressed air as needed, which is provided as supplementary delivery compressed air. In other words, in addition to introducing delivery compressed air into the powder delivery chamber during the dispensing phase of the dense phase powder pump, additional delivery compressed air is supplied at appropriate times or under appropriate circumstances, by means of the auxiliary compressed air inlet device, either immediately upstream or immediately downstream of the powder outlet of the dense phase powder pump.

[0055] 55. The at least one auxiliary compressed air inlet device is preferably implemented via a filter tube through which at least a portion of the powder path between the powder outlet valve and the powder outlet of the dense phase powder pump extends. Preferably, the powder path downstream of the powder outlet valve of the dense phase powder pump passes through the filter tube for a portion of its length. The filter tube is permeable to compressed air but not to particles of the coated powder. Thus, it is meaningful to form the filter tube, for example, from a microporous material such as a sintered material. The filter tube forms a circumferential wall around the powder path and thus creates a relatively large area through which even a small amount of auxiliary compressed air can flow uniformly into the powder path and influence the powder particle size distribution in terms of powder concentration homogenization.

[0056] 56. However, it is also possible to design an auxiliary compressed air inlet device without a filter element, especially a filter tube. The filter element or filter tube is used solely to prevent powder particles from entering the auxiliary compressed air line connected to the auxiliary compressed air inlet device.

[0057] 57. In order to particularly effectively reduce or avoid flow pulsation in the powder path downstream of the powder outlet of the dense phase powder pump, it is advantageous that auxiliary compressed air is introduced into the powder path downstream of the powder outlet valve of the dense phase powder pump in the form of a pulsating flow via an auxiliary compressed air inlet device. Thus, the pulse frequency of the auxiliary compressed air should be at least the same as the frequency of the powder delivery chamber, at which a portion of the powder is distributed from the powder delivery chamber.

[0058] 58. A preferred embodiment of the dense-phase powder pump of the present invention specifies that the pulse frequency of the auxiliary compressed air is the same as the frequency of the powder delivery chamber; that is, the same as the frequency at which a portion of the powder is dispensed from the powder delivery chamber. In conjunction with this, it is preferable that a mechanism for supplying the pulsating auxiliary compressed air to the at least one auxiliary compressed air inlet device is provided, such that the mechanism for supplying the pulsating auxiliary compressed air is advantageously designed such that the auxiliary compressed air is supplied to the at least one auxiliary compressed air inlet device in the opposite phase to the powder dispensing cycle. This ensures that when the powder outlet valve is closed, the auxiliary compressed air is always supplied to the powder path downstream of the powder outlet valve. This measure particularly ensures that the flow rate in the powder line downstream of the powder outlet of the dense-phase powder pump remains constant without any fluctuations.

[0059] 59. The present invention is also based, in particular, on the understanding that, especially in the case of a dense phase powder pump designed as a single-chamber dense phase powder pump, it is advantageous to supply auxiliary compressed air at the powder outlet of the dense phase powder pump as additional delivery compressed air, wherein when the volume of the additional compressed air supplied to the powder path downstream of the powder outlet valve during the suction phase of the powder delivery chamber is substantially the same as the volume of the delivery compressed air supplied to the powder delivery chamber during the powder distribution phase (which is used to pneumatically discharge said portion of the powder previously sucked into the powder delivery chamber), the powder / air mixture downstream of the powder outlet of the dense phase powder pump flows more uniformly through the powder line.

[0060] 60. In order to realize this understanding in the dense phase powder pump of the present invention, on the one hand, it is conceivable to provide a mechanism for supplying pulsating auxiliary compressed air to the at least one additional pressure inlet device, such that the mechanism adapts the volume of auxiliary compressed air supplied to the powder path to the volume of delivery compressed air supplied to the powder delivery chamber.

[0061] 61. When the aerodynamic resistance generated when the conveying compressed air is supplied to the powder conveying chamber and the aerodynamic resistance generated when the auxiliary compressed air is supplied to the powder path are substantially the same, complex compressed air volume control can be particularly eliminated. To achieve this, it is advantageous that at least the basic components of the auxiliary compressed air inlet device (i.e., the components required for supplying auxiliary compressed air to the powder path) have the same structure as the basic components of the powder conveying chamber (i.e., the components of the powder conveying chamber required for supplying conveying compressed air during the distribution phase of the powder conveying chamber). For example, in this case, it is conceivable that the auxiliary compressed air inlet device includes a chamber wall, at least a portion of the length of which is formed by a filter, which surrounds the powder path and separates it from an intermediate chamber that surrounds the filter and is formed between the filter and the housing of the auxiliary compressed air inlet device. The filter of at least the additional compressed air inlet device should thus be structurally identical to the filter of the powder conveying chamber.

[0062] 62. On the other hand, it is also conceivable to provide a control device that can automatically adjust, preferably automatically control or adjust, the frequency of the auxiliary compressed air according to the powder distribution frequency of the powder conveying chamber. This occurs in particular by adapting the pulse frequency of the auxiliary compressed air to the frequency of the powder conveying chamber, wherein when the dense phase powder pump is in its suction phase (in which the powder inlet valve is open and the powder outlet valve is closed), the auxiliary compressed air is advantageously always supplied to the powder path after the powder outlet valve of the dense phase powder pump, thereby ensuring that a sufficient volume of conveying compressed air required for conveying the coating powder is always used.

[0063] 63. However, it is also conceivable that, during the dispensing phase of the dense phase powder pump, auxiliary compressed air may be additionally introduced into the powder path after the powder outlet valve of the dense phase powder pump.

[0064] 64. However, when the dense phase powder pump is in its suction phase, supplying auxiliary compressed air only through the auxiliary compressed air inlet device to the powder path allows for a reduction in the source (compressed air, and therefore energy) required to operate the dense phase powder pump. This also prevents excessive delivery compressed air in the powder path downstream of the dense phase powder pump's powder outlet, thus preventing powder particles from being expelled from the spray at units (powder spray guns or similar devices for spraying coating powders) located downstream of the dense phase powder pump.

[0065] 65. In this case, it is particularly advantageous that the control device is capable of regulating, preferably automatically controlling or adjusting, the volume of auxiliary compressed air flowing through the auxiliary compressed air inlet device per unit time, the volume of which is introduced into the powder path after the powder outlet valve of the dense phase powder pump according to the total amount of powder conveyed per unit time.

[0066] 66. Regarding a method for conveying coating powder from a first powder reservoir to a second powder reservoir disposed downstream of the first powder reservoir, or to a powder spraying gun disposed downstream of the first powder reservoir, or a similar apparatus for spraying coating powder, the present invention specifies that the method comprises method steps of providing a powder spraying apparatus including the dense-phase powder pump of the present invention and at least one spraying gun, and method steps of performing a specific operating cycle, wherein the specific operating cycle comprises the following cyclic steps:

[0067] 67.a) A negative pressure is generated in at least one powder delivery chamber of the dense phase powder pump to draw coating powder into the powder delivery chamber through the open powder inlet valve of the dense phase powder pump while the powder outlet valve of the dense phase powder pump is closed.

[0068] 68.b) Close the powder inlet valve and open the powder outlet valve;

[0069] 69.c) While the powder inlet valve is closed, compressed gas is introduced into the powder conveying chamber to distribute coating powder from the powder conveying chamber through the open powder outlet valve; and

[0070] 70.d) Close the powder outlet valve and open the powder inlet valve.

[0071] 71. According to one aspect of the method of the invention, in the cyclic step c), purge air is supplied to the powder path at at least one point in the powder outlet region of the powder conveying chamber. Alternatively or additionally, in the cyclic step d), purge air is supplied to the powder path at at least one point in the powder inlet region of the dense phase powder pump. Attached Figure Description

[0072] 72. Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings.

[0073] 73. Figure 1 This is a schematic diagram and isometric view of an exemplary embodiment of the dense phase powder pump of the present invention, which has two powder delivery chambers arranged parallel to each other;

[0074] 74. Figure 2 yes Figure 1 Schematic diagram and exploded view of an exemplary embodiment of the dense phase powder pump of the present invention;

[0075] 75. Figure 3 It is based on Figure 1 A schematic diagram illustrating the operating principle of an exemplary embodiment of the dense-phase powder pump of the present invention; and

[0076] 76. Figure 4 It is based on Figure 1A pneumatic schematic diagram of an exemplary embodiment of the dense phase powder pump of the present invention. Detailed Implementation

[0077] 77. The following will be referenced. Figure 3 The illustrations in the figure first describe the working principle of a dense phase powder pump 1 according to an exemplary embodiment of the present invention, which uses two powder delivery chambers 2, 2' arranged in parallel.

[0078] 78. For example Figure 3 As schematically shown, each of the two parallel powder conveying chambers 2, 2' has a main body region 3, particularly cylindrical, having an effective flow cross-sectional area that is at least substantially uniform. Each of the two powder conveying chambers 2, 2', particularly the cylindrical main body region 3, has a cylindrical, particularly circular, sleeve 4 and a filter element 5 housed within the sleeve 4. The filter element 5 of the main body region 3 of the powder conveying chambers 2, 2' is particularly a cylindrical filter element 5.

[0079] 79. Each powder conveying chamber 2, 2' has a powder inlet with a powder inlet valve 6 and a powder outlet with a powder outlet valve 7. The corresponding powder inlet valve 6 will also be referred to below as the "first valve" or "suction-side valve". The powder outlet valve 7 will also be referred to as the "second valve" or "conveyor-side valve".

[0080] 80. A transition region 8 is provided at the corresponding suction and conveying end regions of the main body area of ​​powder conveying chambers 22 and 2', which is designed to reduce the effective flow cross-sectional area of ​​powder conveying chambers 22 and 2' to the effective flow cross-sectional area of ​​the corresponding connected powder pipeline 9, or to the effective flow cross-sectional area of ​​valves 6 and 7 arranged between powder conveying chambers 22 and 2' and powder pipeline 9. Thus, the transition region 8 is at least partially implemented as a conical region.

[0081] 81. The corresponding transition regions 8 arranged on the suction side end region of the main body region 3 of the powder conveying chambers 2, 2' and on the conveying side end region of the main body region 3 of the powder conveying chambers 2, 2' are designed as components separate from the main body region 3, which are detachably or detachably connected to the main body region 3 of the powder conveying chambers 2, 2'.

[0082] 82. The transition region 8 is used to adapt / reduce the nominal width of the main body region 3 of the powder conveying chambers 2 and 2' (i.e., the inner diameter of the main body region 3 of the powder conveying chambers 2 and 2') to the nominal width of the corresponding connecting powder pipeline 9 or the nominal width of the intervention valves 6 and 7, respectively.

[0083] 83. The transition region 8 includes a particularly conical filter element 10 housed in the filter housing 11.

[0084] 84. During the suction process, a vacuum (negative pressure) is generated in one of the powder delivery chambers 2 and 2' of the dense phase powder pump 1. The negative pressure draws the powder to be delivered, especially coating powder, into the powder delivery chamber 2 or 2' through the corresponding powder inlet. The fine-pore filter element 5 in the main body region 3 of the powder delivery chamber 2 or 2' separates the powder. During the suction process, the powder delivery chamber 2 or 2' is closed on the corresponding suction side or delivery side by the corresponding delivery side valve.

[0085] 85. On the other hand, during the conveying process, the suction-side valve 6 on the powder inlet side of the powder conveying chambers 2, 2' is closed, while the conveying-side valve 7 is opened. During the suction process, the coating powder previously sucked into the powder conveying chambers 2, 2' is then forced out of the powder conveying chambers 2, 2' and further conveyed through the fine-pore filter element 5 of the main body region 3 by the positive pressure established by compressed air.

[0086] 86. From Figure 3 As can be seen, the suction and conveying processes alternate between two parallel powder conveying chambers 2 and 2'. In other words, the two parallel powder conveying chambers 2 and 2' operate in opposite phases.

[0087] 87. Figure 3 The schematic diagram also shows the operating modes of the conical filter element 10 in the powder outlet end area of ​​the main body area 3 of the powder conveying chambers 2 and 2' and in the transition area 8 at the powder inlet or conveying end area.

[0088] 88. Specifically, according to an embodiment of the invention, during the conveying process, positive pressure is applied not only in the annular space between the cylindrical filter element 5 of the main body region 3 and the cylindrical sleeve 4 of the main body region 3, so that when the suction-side valve 6 on the powder inlet side of the powder conveying chambers 2, 2' is closed and the conveying-side valve 7 is open, positive pressure is also applied to the corresponding conical filter element 10 of the transition region 8. In this way, during the conveying process, purge air in the form of compressed air is supplied to the two end regions of the powder conveying chambers 2, 2' via the conical filter element 10 to keep the end regions free of powder deposits or to remove powder deposits at the end regions.

[0089] 89. The following will be referenced Figure 1 and Figure 2 The illustration depicts an exemplary embodiment of a dense-phase powder pump 1 using two parallelly arranged powder delivery chambers 2, 2' according to an embodiment of the present invention.

[0090] 90.Specifically, Figure 1The structure of a dense phase powder pump 1 having two parallel powder delivery chambers 2, 2' according to an exemplary embodiment of the present invention is shown in isometric view. The dense phase powder pump 1 has two powder delivery chambers 2, 2', each of which has a cylindrical body region 3, the body region 3 having a cylindrical, and particularly cylindrical, sleeve 4, and a permeable filter element 5 disposed within the sleeve 4. The filter element 5 is preferably a rigid body made of sintered material, preferably made of sintered metal (e.g., bronze or aluminum), sintered plastic, or a mixture of sintered materials.

[0091] 91. Especially from Figure 2 As shown in the exploded view, each powder conveying chamber 2, 2' has a transition region 8 at the suction side and the conveying side, which is detachably connected to or can be connected to a portion of the main body region 3 and the powder conveying chamber 2, 2'. The transition region 8 is thus used to adapt / reduce the nominal width of the main body region 3 of the powder conveying chamber 2, 2' to the nominal width of the corresponding suction-side valve 6 or conveying-side valve 7.

[0092] 92. In order to reduce the nominal width (i.e., the inner diameter of the cylindrical main body region 3 of the powder conveying chambers 2, 2') accordingly to the (reduced) nominal width of the corresponding valves 6, 7 or the corresponding powder line 9, each transition region 8 has a filter element 10, which tapers in particular in the direction of the valves 6, 7 or the flow line.

[0093] 93. Similar to the filter element 5 in the main region 3, the filter element 10 is preferably a rigid body, particularly made of sintered material, preferably sintered metal (e.g., bronze or aluminum) or sintered plastic or a mixture of sintered materials. Of course, other embodiments in which the filter element 10 in the transition region 8 tapers tapered in the direction of the respective valves 6, 7 are also conceivable.

[0094] 94. The filter element 10, tapering tapered in the direction of the respective valves 6, 7, defines the effective flow cross-sectional area of ​​the transition region 8 so that the nominal width of the main body region 3 of the powder conveying chambers 2, 2' is adapted to the nominal width of the valves 6, 7 connected to the respective end regions of the powder conveying chambers 2, 2'.

[0095] 95. From Figure 2 As can be seen from the exploded view, the corresponding tapered filter element 10 of the transition region 8 is detachably connected to the corresponding end region of the main body region 3 of the powder conveying chambers 2, 2', in particular by means of a screw connector or other releasable joint, such as a bayonet connector or a lockable plug connector.

[0096] 96. Each transition region 8 also has a corresponding filter housing 11 in which a tapered filter element 10 can be housed. An air gap is formed between the interior of the filter housing 11 and the exterior of the tapered filter element 10, which can be pressurized as needed via a corresponding air line.

[0097] 97. A first pinch valve 6 connected to the suction side end region of powder conveying chambers 2 and 2' is provided. Figure 1 and Figure 2 The powder inlet of each powder delivery chamber 2, 2' of the dense phase powder pump 1 is schematically shown. A second pinch valve 7 is connected to the corresponding delivery side end region of the powder delivery chamber 2, 2', that is, to the delivery side end region of the transition region 8 of the powder delivery chamber 2, 2'.

[0098] 98. Although in the exemplary embodiments the pinch valves are always used as powder inlet valve 6 and powder outlet valve 7, they can of course be of any type.

[0099] 99. In the illustrated embodiment, a supply line branch of the Y-connector 12 connects the powder inlet side of the two first (suction-side) valves 6 to a powder supply line 9, which leads, for example, to a powder container (not shown). A hose connector is thus used to connect the powder inlet side of the two first valves 6 (pinch valves) to the supply line branch of the Y-connector 12.

[0100] 100. However, it is also conceivable that, instead of the Y-connector 12, the corresponding powder inlet side of the first (suction side) valve / pinch valve 6 is fluidly connected to one or two different powder containers via a separate powder supply line.

[0101] 101. In the illustrated embodiment, a branch of the distribution line (e.g., also a Y-shaped line connector 12) connects the powder outlets of the two second (delivery side) valves / pinch valves 7 to one end of a powder distribution hose 9, the other end of which leads to another powder container (not shown). Although the powder distribution line can be a rigid tube, it is preferably a flexible hose.

[0102] 102. In Figure 1 and Figure 2 In the illustrated embodiment, each of the powder delivery chambers 2, 2' is housed and secured in the mounting member 13. The powder delivery chambers 2, 2' are connected to the mounting member 13, in particular, by removable screws or bayonet couplings.

[0103] 103. The following is based on reference. Figure 2 The exploded view describes in more detail the structure of each powder delivery chamber 2, 2' used in the dense phase powder pump 1.

[0104] 104. Therefore, each powder conveying chamber 2, 2' is divided into a main region 3 and two transition regions 8, the main region having at least substantially uniform effective flow cross-sectional area, and the two transition regions having conical flow cross-sectional areas arranged at the respective end regions of the main region 3.

[0105] 105. Specifically, the main body region 3 of each powder conveying chamber 2, 2', particularly the cylindrical type, is associated with a corresponding sleeve 4, the interior of which has a designated, breathable, and at least substantially cylindrical filter element 5. The sleeve 4, which houses the filter element 5, forms the main body region 3 of each powder conveying chamber 2, 2'.

[0106] 106. The aforementioned type of suction-side transition region 8 is provided at the suction-side end region of the main body region 3 of the powder conveying chambers 2 and 2'. In other words, the suction-side end region of the main body region 3 is provided with a tapered filter element 10, which has a corresponding housing region 11 associated with the tapered filter element 10. This metaphorically applies equally to the transition region 8 correspondingly provided at the conveying-side end region of the main body region 3 of the powder conveying chambers 2 and 2'.

[0107] 107. In an exemplary embodiment of the dense-phase powder pump 1 of the present invention shown in the accompanying drawings, the first (suction side) valve 6 and the second (delivery side) valve 7 are each preferably designed as pinch valves.

[0108] 108. Each pinch valve 6, 7 has a pinch valve body 15, which has an inlet-side flange and an outlet-side flange. A resiliently deformable valve element 14 is housed within the pinch valve body 15. The resiliently deformable valve element 14 is, in particular, a resiliently deformable hose section. Each flange has a powder line connector (hose connector) to which a powder line 9 (powder hose) can be connected.

[0109] 109. For example, from according to Figure 4 As can be seen from the pneumatic diagram, the tapered filter element 10 is arranged in the corresponding filter housing 11 of each transition region 8, so that the inlet of the tapered filter element can be fluidly connected with the outlet of the main body region 3 of the powder conveying chambers 2, 2'.

[0110] 110. The filter housing 11 of the transition zone 8 includes a connector 16 for supplying compressed air as needed into the space formed between the inner wall of the filter housing 11 and the tapered filter element 10 disposed inside the filter housing 11. When compressed air is supplied, the areas formed by the transition zone 8 in the delivery chambers 2, 2' are flushed accordingly, and powder deposits there are removed or prevented from accumulating there.

[0111] 111. In an exemplary embodiment of the dense-phase powder pump 1 of the present invention shown in the accompanying drawings, each first valve 6 and second valve 7 is designed as a pinch valve, whereby each pinch valve 6, 7 is provided with an elastically deformable valve element 14 arranged within a corresponding pinch valve housing 15, such that the inlet of the pinch valve 6, 7 is fluidly connected to the outlet of the pinch valve 6, 7 through the valve element formed as an elastically deformable valve element 14.

[0112] 112. The pinch valve housing 15 has a connector 17 for supplying compressed air as needed into the space formed between the inner wall of the pinch valve housing 15 and the valve element 14 disposed within the pinch valve housing 15. When compressed air is supplied, the valve element 14 elastically deforms, thereby interrupting the fluid communication between the inlet and outlet of the pinch valves 6, 7. However, when there is no compressed air in the gap between the inner wall of the pinch valve housing 15 and the valve element 14 disposed within the pinch valve housing 15, the previously elastically deformed valve element 14 returns to its initial state, wherein the inlet and outlet of the pinch valve housing 15 are in fluid communication.

[0113] 113. A vacuum connector may also be connected via at least one of the connectors of the pinch valves 6 and 7 to discharge compressed air from the previously introduced gap in order to quickly open the pinch valve.

[0114] 114. The tapered filter element 10 of the transition region 8 is preferably designed to be air-permeable on a circumference of at least 180° and preferably 360°. The filter element 10 is preferably composed of a microporous material such that it is permeable to air but impermeable to the coating powder. For example, the filter element 10 may be made of a sintered body (e.g., metal or plastic) or a mixture of materials comprising metal or plastic. It may also be made of different materials and / or formed from a filter membrane.

[0115] 115. The filter orifices of the filter element 10 are preferably designed such that compressed air is guided into the powder path formed / defined by the transition region 8 over a relatively large powder path area in both the circumferential and longitudinal directions of the filter element 10. The micropores of the filter element 10 may be inclined radially or axially toward the powder path.

[0116] 116. Figure 4 It shows Figure 1 / Figure 2 An exemplary embodiment of the pneumatic diagram of the dense phase powder pump 1, schematically depicted in the figure.

[0117] 117. For example Figure 4 As shown schematically, in Figure 4The control device 100, schematically shown, is used to operate the dense phase powder pump 1. The control device 100 is designed to properly control the various actuated parts of the dense phase powder pump 1, especially the control valves S1 to S8, and to coordinate their actuation.

[0118] 118. On the one hand, this involves coordinating the activation of pinch valves 6 and 7 via control valves S5, S6, and S7. On the other hand, it involves appropriately activating control valves S1, S2, and S4 to coordinate the supply of compressed air to the corresponding main areas 3 of the two powder conveying chambers 2 and 2', or to coordinate the application of appropriate vacuum, respectively. It also involves appropriately activating control valve S1 to coordinate the supply of compressed air, as purging air, to the corresponding transition areas 8 of the main areas of the two powder conveying chambers 2 and 2'.

[0119] 119. According to Figure 4 The pneumatic diagram shown is characterized, in particular, that dedicated compressed air is supplied to the corresponding transition regions 8 of the suction-side end regions and the conveying-side end regions of the powder conveying chambers 2, 2'. Specifically, this is preferably ensured to occur simultaneously with the supply of compressed air to the main body region 3 of the respective powder conveying chambers 2, 2'.

[0120] 120. Therefore, the so-called cone flushing; that is, flushing in the corresponding transition areas of the powder conveying chambers 2, 2', is only initiated during the cleaning cycle.

[0121] 121. However, as an alternative or supplement to this, it is also conceivable to initiate such conical cleaning and to do so during powder conveying operations. In this case, it is particularly conceivable that the conical cleaning is operated at a first intensity during powder conveying mode and at a higher second intensity during cleaning mode. The additional air volume introduced during the cleaning process will also lead to an increase in cleaning efficiency.

[0122] 122. The present invention is not limited to the embodiments shown in the accompanying drawings, but rather arises from a comprehensive overall consideration of all features disclosed herein.

[0123] 123. List of reference numerals in attached figures

[0124] 124.1 Dense Phase Powder Pump

[0125] 125.2, 2' Powder conveying chamber

[0126] 126.3 Main Area

[0127] 127.4 casing

[0128] 128.5 filter element

[0129] 129.6 Powder Inlet Valve

[0130] 130.7 Powder outlet valve

[0131] 131.8 Transition Zone

[0132] 132.9 Powder Pipeline

[0133] 133.10 Conical Filter Element

[0134] 134.11 Filter housing

[0135] 135.12 Y-type connector

[0136] 136.13 Installation Components

[0137] 137.14 Valve Components (Pinch Valve)

[0138] 138.15 pinch valve housing

[0139] 139.16 Connector on filter housing

[0140] 140.17 Fittings on the body of the pinch valve

[0141] 141.100 Control Device

[0142] 142.S1-S8 control valves

Claims

1. A powder conveying chamber (2, 2') of a dense-phase powder pump (1) for conveying powder, wherein, The powder delivery chamber (2, 2') includes at least one air exchange opening, which is separate from the purge air outlet of the end region for alternately fluidly connecting to a vacuum line or vacuum source, or a compressed air supply line or compressed air source, for drawing powder into the powder delivery chamber (2, 2') or pneumatically discharging a portion of the powder present in the powder delivery chamber (2, 2'), wherein the powder delivery chamber (2, 2') includes an end region, via which the powder delivery chamber (2, 2') is fluidly connected to or can be fluidly connected to a powder line (9), wherein the powder The end regions of the powder delivery chambers (2, 2') are configured as transition regions (8) and are designed to reduce the effective flow cross-sectional area of ​​the powder delivery chambers (2, 2') to that of the powder pipeline (9) and / or to that of the valves (6, 7) arranged between the powder delivery chambers (2, 2') and the powder pipeline (9). The end regions are equipped with a purging system, through which purging air in the form of compressed air can be supplied to the end regions to keep the end regions free of powder deposits or to remove powder deposits at the end regions. Its features are, At least a portion of the wall region of the end region forming the powder conveying chamber (2, 2') is designed as a porous wall region that allows compressed air to pass through but substantially prevents powder from passing through.

2. The powder conveying chamber (2, 2') according to claim 1, wherein, The end region of the powder conveying chamber (2, 2') has at least one cleaning air outlet for blowing out cleaning air from the powder conveying path defined by the powder conveying chamber (2, 2') and the transition region (8) as needed.

3. The powder conveying chamber (2, 2') according to claim 2, wherein, The cleaning system has a filter element (10) that is at least partially tapered and tapered, the filter element being permeable to air but not to powder, wherein the filter element (10) is housed in a filter housing (11) which is supplied with cleaning air in the form of compressed air, wherein the filter element (10) is releasably connected to the end region of the cylindrical body region of the powder delivery chamber (2, 2') through its larger diameter end region, and wherein the filter element (10) is releasably connected to the end region of the powder pipeline (9) or the end region of a valve (6, 7) disposed between the powder delivery chamber (2, 2') and the powder pipeline (9) through its smaller diameter end region.

4. The powder conveying chamber (2, 2') according to claim 3, wherein, A control device (100) is assigned to the cleaning system, the control device being configured to fluidly connect at least one cleaning air outlet of the end region of the powder conveying chamber (2, 2') to a compressed air supply line or a compressed air source when needed, wherein the control device (100) is configured to fluidly connect at least one cleaning air outlet of the end region of the powder conveying chamber (2, 2') to the compressed air supply line or the compressed air source during cleaning operations; and / or The control device (100) is designed to fluidly connect at least one purge air outlet of the end region of the powder conveying chamber (2, 2') to the compressed air supply line or the compressed air source during the powder output cycle of the powder conveying chamber (2, 2').

5. The powder conveying chamber (2, 2') according to claim 4, wherein, The control device (100) is designed to adjust the volume of compressed air supplied to at least one cleaning air outlet of the end region of the powder conveying chamber (2, 2') per unit time according to the operating state and / or operating cycle of the powder conveying chamber, wherein the control device (100) is designed to supply a larger volume of compressed air to the at least one cleaning air outlet of the end region of the powder conveying chamber (2, 2') per unit time during cleaning operation compared to the volume of compressed air supplied to the at least one cleaning air outlet per unit time during the powder output cycle.

6. The powder conveying chamber (2, 2') according to claim 5, wherein, The end regions of the powder conveying chambers (2, 2') are fluidly connected to or can be fluidly connected to the powder pipeline (9) via valves (6, 7), wherein the valves (6, 7) present an effective flow cross-sectional area in their open state, and wherein the end regions of the powder conveying chambers (2, 2') are designed to reduce the effective flow cross-sectional area of ​​the powder conveying chambers (2, 2') to the effective flow cross-sectional area of ​​the valves (6, 7) in their open state.

7. The powder conveying chamber (2, 2') according to claim 6, wherein, The powder conveying chamber (2, 2') includes a cylindrical main body region (3) having at least substantially uniform effective flow cross-sectional area.

8. The powder conveying chamber (2, 2') according to claim 7, wherein, The powder delivery chambers (2, 2') have a first end region and a second end region arranged opposite to it, wherein the powder delivery chambers (2, 2') are fluidly connected to or are capable of being fluidly connected to a first powder line (9) via the first end region, and are fluidly connected to or are capable of being fluidly connected to a second powder line (9) via the second end region, wherein the first end region and / or the second end region of the powder delivery chambers (2, 2') are implemented as transition regions (8) and are designed to reduce the effective flow cross-sectional area of ​​the powder delivery chambers (2, 2') to the effective flow cross-sectional area of ​​the corresponding powder line (9), and wherein a cleaning system is always allocated to the first end region and / or the second end region, and cleaning air in the form of compressed air is capable of being supplied to the corresponding end regions via the cleaning system in order to keep the corresponding end regions free of powder deposits or remove powder deposits at the end regions.

9. A dense-phase powder pump (1) for conveying coating powder from a first powder reservoir to a downstream second powder reservoir or to a downstream powder spray gun or similar device for spraying coating powder, wherein, The dense-phase powder pump (1) has at least one powder delivery chamber (2, 2') according to any one of claims 1 to 8, the powder delivery chamber being fluidly connected to or capable of being fluidly connected to the first powder reservoir via a powder inlet, and fluidly connected to or capable of being fluidly connected to the second powder reservoir or the powder spray gun or the similar device for spraying coating powder via a powder outlet, wherein at least one powder inlet valve (6) is provided at the powder inlet, and at least one powder outlet valve (7) is provided at the powder outlet.

10. The dense phase powder pump (1) according to claim 9, wherein, The at least one powder inlet valve (6) and the at least one powder outlet valve (7) have the same effective flow cross-sectional area in their respective open states.

11. The dense phase powder pump (1) according to claim 9, wherein, The powder inlet valve (6) in its open state has a larger effective flow cross-sectional area than the powder outlet valve (7) in its open state.

12. The dense phase powder pump (1) according to claim 10, wherein, The dense phase powder pump (1) is designed as a single-chamber dense phase powder pump (1), and the dense phase powder pump (1) has only a single powder delivery chamber (2, 2') for conveying coating powder.

13. The dense phase powder pump (1) according to claim 10, wherein, The dense phase powder pump (1) is designed as a multi-chamber dense phase powder pump (1), and the dense phase powder pump (1) has multiple powder delivery chambers connected in parallel to each other for conveying coating powder.

14. The dense phase powder pump (1) according to claim 9, wherein, The at least one powder conveying chamber (2, 2') has a powder inlet at a first end region and a powder outlet at a second end region arranged opposite to each other, wherein the at least one powder inlet valve (6) and the at least one powder outlet valve (7) are respectively arranged at opposite end regions of the at least one powder conveying chamber (2, 2').

15. The dense phase powder pump (1) according to claim 9, wherein, The at least one powder conveying chamber (2, 2') has a powder channel at one end region, the powder channel serving as both a powder inlet and a powder outlet, wherein the at least one powder inlet valve (6) and the at least one powder outlet valve (7) are always disposed in the powder channel.

16. The dense phase powder pump (1) according to claim 15, wherein, A distributor is also provided for fluidly connecting the powder passage of the at least one powder conveying chamber (2, 2) to the at least one powder inlet valve (6) on one side and to the at least one powder outlet valve (7) on the other side.

17. The dense phase powder pump (1) according to claim 9, wherein, A control device (100) is also provided to control the at least one powder inlet valve (6) and / or the at least one powder outlet valve (7) to alternately apply positive and negative pressure in the at least one powder conveying chamber (2, 2').

18. The dense phase powder pump (1) according to claim 17, wherein, The at least one powder inlet valve (6) and the at least one powder outlet valve (7) are individually controllable.

19. The dense phase powder pump (1) according to claim 18, wherein, The at least one powder inlet valve (6) and the at least one powder outlet valve (7) are each designed as pinch valves with a flexible elastic hose (14) as a valve passage, the flexible elastic hose (14) being able to be squeezed together in a pressure chamber (15) surrounding the hose (14) by actuating compressed air in order to close the respective valves (6, 7).

20. The dense phase powder pump (1) according to claim 17, wherein, The control device (100) is provided, which is designed to alternately connect at least one air exchange opening of the at least one powder delivery chamber (2, 2') to a vacuum line or vacuum source for drawing coating powder into the at least one powder delivery chamber (2, 2') through the open at least one powder inlet valve (6) when the at least one powder outlet valve (7) is closed, or to a compressed air supply line or compressed air source for pneumatically discharging a portion of the powder present in the at least one powder delivery chamber (2, 2') through the open at least one powder outlet valve (7) when the at least one powder inlet valve (6) is closed.

21. The dense phase powder pump (1) according to claim 9, wherein, At least one auxiliary compressed air inlet device also discharges into the powder path at at least one point after the at least one powder outlet valve (7) for supplying auxiliary compressed air as supplemental delivery compressed air when needed, wherein the auxiliary compressed air inlet device discharges into the powder path at at least one point between the powder outlet valve (7) and the powder outlet of the dense phase powder pump (1).

22. The dense phase powder pump (1) according to claim 21, wherein, The auxiliary compressed air inlet device is designed to introduce auxiliary compressed air into the powder path in a pulsating flow manner.

23. The dense phase powder pump (1) according to claim 22, wherein, The system also includes a mechanism for supplying pulsed auxiliary compressed air to the at least one auxiliary compressed air inlet device, wherein the pulse frequency of the auxiliary compressed air is at least the same as the frequency of the at least one powder conveying chamber (2, 2'), and a portion of the powder is distributed from the at least one powder conveying chamber (2, 2') at the frequency.

24. The dense phase powder pump (1) according to claim 23, wherein, The pulse frequency of the auxiliary compressed air is the same as the frequency of the at least one powder delivery chamber (2, 2'), a portion of the powder is distributed from the powder delivery chamber (2, 2') at the frequency, and wherein the mechanism for supplying the pulsed auxiliary compressed air to the at least one auxiliary compressed air inlet device is designed such that the auxiliary compressed air is supplied to the at least one auxiliary compressed air inlet device in a manner opposite to the powder distribution cycle of the at least one powder delivery chamber (2, 2').

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