Relief valve and a hose device for dust collectors, a dust collector and a method for operating a dust collector

Abstract

A hose device may include a flexible hose device body having a first end configured to be attached to a cyclone and a second end with a free opening. The hose device may also include a plurality of weights affixed between the first end and the second end. When subjected to suction forces from a vacuum of the cyclone, the second end may be sucked upwards such that the plurality of weights hingedly swing toward the first end and the hose device body is in a retracted configuration. When released from the suction forces of the cyclone, the plurality of weights hingedly swing away from the first end and the hose device body extends downwards into an extended configuration by the gravity forces acting upon the weights, in the absence of the suction forces, to expand a size of the free opening.

Claims

1. A dust collector comprising: a cyclone; and a hose device comprising a hose device body having a first end configured to be attached to the cyclone and a second end with a free opening, the hose device body being flexible; a plurality of weights affixed to the hose device body; wherein, when subjected to suction forces from a vacuum of the cyclone, the second end of the hose device body is sucked upwards such that the plurality of weights hingedly swing toward the first end of the hose device body, against gravity forces acting upon the weights, and the hose device body is in a retracted configuration; wherein, when released from the suction forces of the cyclone, the plurality of weights hingedly swing away from the first end of the hose device body and the hose device body extends downwards into an extended configuration by the gravity forces acting upon the weights, in the absence of the suction forces, to expand a size of the free opening.

2. The dust collector of claim 1, wherein the weights are evening distributed around the hose device body.

3. The dust collector of claim 1, wherein each weight extends from proximate to the first end of the hose device body to proximate to the second end of the hose device body.

4. The dust collector of claim 1, wherein each weight comprises a pointed shape at an end of the weight proximate the second end of the hose device body.

5. The dust collector of claim 1, wherein the hose device body comprises a conical shape in the extended configuration.

6. The dust collector of claim 1, wherein the hose device body is mounted at a bottom of the cyclone and the hose device body hangs down from a first end disposed at the bottom of the cyclone.

7. The dust collector of claim 1 further comprising a dust bag affixed to the cyclone such that the hose device is disposed within the dust bag.

8. The dust collector of claim 1 further comprising a dust bag that hangs down from the cyclone.

9. The dust collector of claim 8, wherein, when the hose device body transitions to the extended configuration, accumulated dust within the hose device body falls down into the dust bag through the free opening.

10. The dust collector of claim 8, wherein, in the presence of the suction forces from the cyclone, the hose device prevents the dust bag from being sucking into the cyclone.

11. The dust collector of claim 1, wherein, in the presence of the suction forces from the cyclone, a portion of the hose device body moves inwards and upwards towards the cyclone.

12. The dust collector of claim 1, wherein, in the presences of the suction forces from the cyclone, each weight pivots upwards about an upper end of the weight.

13. The dust collector of claim 1 wherein the free opening permits air to pass through the hose device body while in the hose device body is in the retracted configuration.

14. The dust collector of claim 1, wherein the hose device comprises a rim with fasteners configured to engage with a bottom of the cyclone to secure the hose device body to the cyclone.

15. The dust collector of claim 1, wherein each weight has an oblong shape.

16. A hose device comprising: a hose device body having a first end configured to be attached to a cyclone and a second end with a free opening, the hose device body being flexible; a plurality of weights affixed between the first end and the second end; wherein, when subjected to suction forces from a vacuum of the cyclone, the second end of the hose device body is sucked upwards such that the plurality of weights hingedly swing toward the first end of the hose device body and the hose device body is in a retracted configuration; wherein, when released from the suction forces of the cyclone, the plurality of weights hingedly swing away from the first end of the hose device body and the hose device body extends downwards into an extended configuration by the gravity forces acting upon the weights, in the absence of the suction forces, to expand a size of the free opening.

17. The hose device of claim 16, wherein the weights are distributed around the hose device body between the first end and the second end.

18. The hose device of claim 16, wherein each weight comprises a pointed shape at an end of the weight proximate the second end of the hose device body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic illustration of an exemplary dust collector according to some example embodiments with the relief valve in closed position.

(2) FIG. 2 is an illustration corresponding to that of FIG. 2 with the relief valve in open position.

(3) FIG. 3 is an illustration of the principle of the relief valve as open.

(4) FIG. 4 illustrates the principle of the relief valve as closed.

(5) FIG. 5 is a perspective view of an exemplary relief valve as open.

(6) FIG. 6 is the relief valve of FIG. 5 as closed.

(7) FIG. 7 is a side view partly in section of an exemplary hose device according some example embodiments in a first position.

(8) FIG. 8 is a view similar to that of FIG. 7 illustrating the hose device in a second position.

(9) FIG. 9 is a view similar to that of FIG. 7 illustrating the hose device in a third position.

(10) FIG. 10 is a perspective view of the hose device of FIG. 7.

(11) FIG. 11 is an explosive view of the hose device of FIG. 10

(12) FIG. 12 is a block diagram illustrating actuation of an inlet valve for pressurized air.

(13) FIG. 13 is a block diagram illustrating governing of the valves according to a further example embodiment.

DESCRIPTION OF EXAMPLES

(14) FIG. 1 is a schematic representation of a dust collector according to an example embodiment. The dust collector has an inlet 4 and an outlet 5 and forms a fluid path for air through the dust collector. The inlet 4 is connected to a grinding machine 6. A motor driven fan acts as a vacuum generating means 3 thereby establishing an air flow through the dust collector from the inlet 4 to the outlet 5 as indicated by the arrows. The dust collector has a primary cleaner 1 and a secondary cleaner 2. The primary cleaner 1 includes a cyclone 7. The secondary cleaner includes a filter 8.

(15) At the bottom of the cyclone 7 there is a dust bag 9 that may be made of plastic. The dust bag 9 is arranged to collect accumulated dust from the cyclone 7. A similar dust bag 10 is mounted beneath the filter 8. The bottom 15 of the cyclone housing 14 and the bottom 17 of the filter housing 16 are configured as grids or nets allowing dust to path therethrough.

(16) Between the secondary cleaner 2 and the vacuum generating means 3 there is a relief valve 100 that in this figure is shown in the closed position. When the relief valve is in the open position (see FIG. 2) it communicates the flow path to the surrounding air which normally is at atmospheric pressure.

(17) On the downstream side of the filter 8 there is an inlet valve 12 for pressurized air from an air tank 11, receiving pressurized air from a compressor 13.

(18) FIG. 1 illustrates the dust collector at normal operation. At normal operation the vacuum generator 3 creates a vacuum in the flow path in the dust collector, by which air with dust particles is forced to flow therethrough. The primary cleaner 1, the cyclone 7, separates most of the dust particles, typically 95% or more. The separated dust is gathered in the cyclone on the walls of the cyclone housing 14 as well as on the bottom 15 thereof. Due to the vacuum prevailing in the cyclone 7 the dust bag will be held sucked up against the grid bottom 15. The remaining dust particles are separated by the filter 8 in the secondary cleaner 2. The dust particles gather on the upstream side of the filter 8 and on the bottom 17 of the filter housing 16. Also the dust bag 10 will be held sucked up against the grid bottom 17.

(19) After the secondary cleaner 2, air that is substantially free from dust flows to the outlet 5 via the vacuum generating means 3.

(20) FIG. 2 represents the same dust collector as FIG. 1 but illustrates it in a deactivated mode of operation. This mode of operation is attained by opening the relief valve 100 as illustrated in the figure. Running of the vacuum generating means 3 is continued without problem also during the deactivated mode of operation, since the major part of the air that flows in through the relief valve 100 flows in direction of the vacuum generating means 3.

(21) The open relief valve 100 eliminates the vacuum within the dust collector. Thereby the dust bags 9, 10 no longer will be sucked up against the respective grid bottom 15, 17. The dust in the cyclone 7 thereby is allowed to fall down into the dust bag 9 through the grid bottom 15, and the dust in the filter housing 16 falls down to its dust bag 10.

(22) When the dust bags 9, 10 are not sucked against the respective grid bottom 15, 17 but are in these fallen down positions they are visible from the outside of the dust collector. An operator thereby will be able to see how much dust is contained in the respective dust bag 9,10 and decide whether it is necessary to exchange a dust bag with an empty one or if it still has capacity to house more dust so that normal operation can continue until later.

(23) After a time period, sufficient long for the dust in the cleaners 1, 2 to fall down into the dust bags 9, 10, the relief valve 100 is shut. Thereby the vacuum pressure within the dust collector is restored and the normal operation mode starts again.

(24) During the period when the relief valve 100 is open cleaning of the filter 8 and the cyclone 7 is possible. This is attained by blowing pressurized air into the dust collector from an air tank 11 through an inlet valve 12. The pressurized air is injected into the dust collector at a location downstream the filter 8 but upstream the relief valve 100. The pressurized air creates a flow through the cleaners 1, 2 in the opposite direction than at normal operation, i.e. as indicated by the arrows A. The reverse flow through the filter 8 cleans it from dust, which falls down into the dust bag 10. The pressurized air also cleans the cyclone 7.

(25) A major fraction of the pressurized air flows towards the vacuum generating means 3 as indicated by the arrow B.

(26) Actuation of the relief valve 100 to the open position may be performed automatically at certain time intervals or in response to sensed operation parameters in the dust collector. Alternatively, opening of the relief valve 100 may be done manually. The relief valve is maintained open a certain period of time that is sufficient to effectively dump the dust into the dust bags 9, 10 and to clean the filter 8 and the cyclone 7. The function of an example of the relief valve 100 will be explained in more detail below with reference to FIGS. 3 and 4.

(27) FIGS. 3 and 4 illustrates the working principle of the relief valve 100 in a schematic example depicted merely for illustrative purpose. FIG. 3 illustrates the relief valve 100 in its closed position when the machine performs its operation. In this position an opening 109 in the valve housing 101, which may be the wall of the duct where the valve is mounted, is covered by a plate-shaped movable member 102 acting as a valve body. A sealing 108 between the valve body and the valve housing 101 seals the upper side of the relief valve from its inner side. At the upper side prevails atmospheric pressure and on the inner side, i. e. within the duct there is vacuum.

(28) A valve stem 103, which is magnetic at least at its ends, carries the movable member 102. An electromagnet 106 holds the valve stem 103 in the shown position and represents a first force exerting means. In addition a pressure spring 104 urges the movable member 102 towards the valve housing 101 and represents a second force exerting means acting in the same direction as the electromagnet 106. The atmospheric pressure P outside the relief valve urges the movable member 102 downwards in the direction of opening the valve. This is prevented by the force of the electromagnet 106.

(29) A short distance below the lower end of the valve stem 103 in this position there is a further electromagnet 107.

(30) At certain intervals the relief valve 100 is to be opened for dust dumping and clean blowing. This may be initiated manually or by means of an opening control means 110. This is performed by breaking the current to the electromagnet 106, so that its force in the upward direction becomes deactivated. The pressure difference between the atmospheric pressure P and the vacuum inside thereby presses the movable member 102 downwards against the action of the pressure spring 104, which is too weak to alone withstand the force from the pressure difference. The relief valve thereby reaches it open position.

(31) The open position is illustrated in FIG. 4. In that position, the lower end of the valve stem 103 has reached the electromagnet 107. The electromagnet 107 is in activated stage when the valve stem 103 reaches it and therefor attracts the valve stem 103. The electromagnet 107 acts as a third force exerting means, and the force dominates over the force from the pressure spring 104 so that the relief valve 100 is maintained open as long as the electromagnet 107 is activated.

(32) After a certain period of time, the electromagnet 107 is deactivated. The pressure spring 104 thereby presses the movable member 102 up against the valve housing 101. The spring force is not sufficient to alone withstand the pressure difference. However, with the movement of the movable member 102 also the valve stem 103 moves up towards the upper electromagnet 106, which in this moment is brought into activated state again. The electromagnet 106 will catch the end of the valve stem 103 and maintain the relief valve 100 closed.

(33) The activation time of the lower electromagnet should be sufficient to allow emptying of the dust in the cleaner down in the dust bag and to give sufficient time for clean blowing. The activation time is controlled by a second control means 111. This may be governed from a timer 112 or from a sensor 113.

(34) The opening control means 110 and the second control means may constitute parts of a common general relief valve controller arranged as a programmable logic controller.

(35) FIGS. 5 and 6 illustrate an example of a relief valve 300 according to some example embodiments in the closed and open position, respectively. The relief valve 300 is arranged at the top of a duct 314 communicating with the interior of the dust collector at a location corresponding to that illustrated in FIG. 1. Communication with the ambient air is accomplished by the inlets 315 spaced around the cylindrical part 316 of the valve housing 301.

(36) In the closed position of FIG. 5 the atmospheric air is restricted to reach only the space radially outside the cylindrical valve member 302a and axially above a movable member 302. The movable member 302 is an annular plate extending radially outwards from the bottom end of the cylindrical valve body 302a. Inside the walls formed by the movable member 302 and the valve body 302a there is vacuum.

(37) The valve stem 303 is by means of consoles 318 rigidly connected to the valve body 302a. A pressure spring 304 is arranged concentric with the valve stem 303 Further down, the second electromagnet 307 is located a short distance below the valve stem 303.

(38) When the upper electromagnet 306 is deactivated the pressure difference across the annular movable member 302 presses it downwards. The valve body 302a attached thereto thus also moves downwards.

(39) In FIG. 6, the relief valve is in its open position, in which the valve body 302a has opened up for ambient air for flowing into the interior of the valve housing and reach down to the dust collector via the duct 314. At this state the valve stem 303 is captured by the activated lower electromagnet 307, and the consoles 318 of the valve stem are urged against the compression spring 304.

(40) When the lower electromagnet is deactivated the pressure spring 304 pushes the valve stem 303 upwards until it is captured by the upper electromagnet 306 again and thereby returns to its closed position.

(41) FIG. 7 is a side view of a hose device 200 according to an example embodiment. The hose device 200 is mounted at the bottom 215 of a cyclone 207 in a portable, industrial dust collector. The hose device 200 in this example has a conical shape in the open position when no vacuum prevails. It hangs down from a first end 201 attached to the grid means (not visible) at the bottom of the cyclone 207. The lower, second end 202 of the hose device 200 is open.

(42) The material of the hose device 200 is flexible and elastic. The material preferably comprises an elastomer. Preferably, the material comprises rubber, such as natural rubber. Preferably, the material comprises a blend of natural rubber and Styrene-Butadiene Rubber (SBR). The dust bag 209 hangs down from the cyclone 207 to which it is attached and is made of plastic.

(43) On the external side of the hose device are four weights 203 attached evenly distributed around the same. Each weight 203 has a flat oblong shape with the flat side abutting the hose device. Each weight 203 extends a short distance from the upper, first end 201 to a short distance from the lower, second end 202. At the lower end each weight has a pointed shape 204.

(44) The figure illustrates the hose device 200 and the dust bag 209 in the state when no vacuum prevails. Thereby the weights 203 hold the hose device 200 directed downwards so that an opening is formed at its bottom. In this position dust that has been accumulated on the bottom grid of the cyclone 207 will fall down into the dust bag 209. When emptying is finished, the machine in which the cyclone works is ready to operate again and the development of vacuum inside the cyclone 207 is initiated, e. g, by closing a relief valve.

(45) FIG. 8 illustrates the hose device 200 and the dust bag 209 at the beginning when the vacuum starts to act. From the position in FIG. 7, the dust bag 209 will be sucked inwards against the hose device 200.

(46) By the force from the vacuum, the dust bag 209 will push the hose device 200 inwards and upwards, whereby each weight 203 swings like a hinge around its upper end. At the end the hose device 200 and the dust bag 209 reaches the position illustrated in FIG. 9, where the hose device 200 by the vacuum is sucked upwards against the underside of the bottom 215 of the cyclone 207 as indicated by the arrows. For illustrative purpose the hose device in this figure is depicted also in its hanging down position, in this figure indicated at 200a.

(47) Although the hose device 200 is flexible and elastic, it is more rigid than the dust bag 209. Therefore, and because of the weights, the hose device 200 will not be sucked up through the grid means at the bottom 215 of the cyclone 207. The hose device 200 in this position will prevent the dust bag 209 from being sucked up through the grid means. Part of the dust bag 209 will hang down below the hose device 200 as illustrated or be sucked up against it if there remains some air leakage across the hose device 200.

(48) When it is time for dumping dust into the dust bag 209, the vacuum in the cyclone is released by the release valve. In the absence of vacuum, the weights 203 will by gravity swing down so that the hose device 200 reaches it down-directed conical position and the dust will fall through the grid device and through the opening at the bottom of the hose device into the dust bag.

(49) It is to be appreciated that a hose device 200 according to some example embodiments can be mounted to any one of the primary 1 and secondary 2 cleaners in FIGS. 1 and 2. Preferably, hose devices 200 are mounted to both the primary 1 and the secondary 2 cleaner, more specifically, hose devices 200 are suitably mounted to both the cyclone housing 14 and the filter housing 16.

(50) FIG. 10 illustrates the hose device 200 in a perspective view from above as attached to the bottom 215 of a cleaner. The bottom 215 consists of a rim 208 and a grid 205 attached to the rim 208. By bayonet-fasteners 210 on the rim 208, the bottom 215 is easily detachable from the cylindrical wall (not shown) of the cleaner. Each of the four weights 203 are attached to the inside of the hose device 200 and secured on the outside by a clamp 212.

(51) FIG. 11 shows the hose device 200 of FIG. 10 in an explosive view. The upper end 201 of the hose device 200 is attachable to the circumferential of the grid 205 by means of a fastening ring 206 and screws 211.

(52) FIG. 12 illustrates the actuation of the inlet valve 12 (see also FIG. 2) for pressurized air used for clean blowing the filter 8. Opening and closing of the inlet valve 12 is controlled by a clean-blowing control unit 121 initiating opening and closing of the inlet valve 12.

(53) The clean-blowing control unit 121 may be arranged to receive signals from the relief valve 100 when the latter opens, which signals may initiate immediate opening of the inlet valve 12. Alternatively the clean-blowing unit may include a second timer means 122, which is arranged to delay opening of the inlet valve 12 a pre-determined period. The length of this period may be adjustable.

(54) The second timer means 122 may also be arranged to initiate closing of the inlet valve 12 after it has been open a certain time. Also the duration of the opening time may be adjustable.

(55) As an alternative or as a complement to timer means, the clean-blowing control unit may act in response to pressure sensors. In one alternative a pressure sensor 123 containing two pressure sensing spots arranged on either side of the filter 8 senses the pressure drop across the filter 8. At beginning of the clean blowing the pressure drop is relatively high due to the gathering of dust on and within the filter 8. As the dust is blown away from the filter 8, the pressure drop will gradually decrease. The decreasing pressure drop is compared with the initial pressure drop. When the pressure drop has passed below a certain threshold closing of the relief valve is initiated.

(56) In another alternative the pressure in the duct between the inlet valve 12 and the relief valve 100 is sensed by another sensor 124 as an indicator for initiating the closing of the inlet valve 12.

(57) In order to assure that the inlet valve 12 closes before the relief valve 100 the second control means 111 of the relief valve (see FIG. 3) may be governed from the clean-blowing control means 121 preventing the second control means 111 from deactivating the electromagnet 107 unless the inlet valve has closed. This governing may include that closing of the inlet valve 12 initiates deactivation of the electromagnet 107 for closing of the relief valve 100.

(58) The clean-blowing control means 121 is preferably a part of a programmable logic controller that also includes the opening control means 110 and the second control means 111 of the relief valve 100.

(59) FIG. 13 illustrates governing of the inlet valve 12 and the relief valve 400 according to a further example embodiment. It is to be understood that the illustration of the valve governing may relate to a dust collector as illustrated in FIGS. 1 and 2. The relief valve 400 in this example may be of any suitable kind and may be pneumatically actuated. It may be without retaining means or may be provided with retaining means similar to that of the relief valve 100 described above. Both the relief valve 400 and the inlet valve 12 are governed by a central controller 401 with a PLC (programmable logic controller). The central controller governs the time intervals for the opening of the relief valve 400. It also governs the opening and closing of the relief valve 400 and the opening and closing of the inlet valve 12 as well as the timing of these actuations in relation to each other.

(60) A typical example of the actuation of the valves and their timing-relation that may be programmed into the central controller 401 is that the relief valve 400 opens once every third minute. At opening of the relief valve 400, the time sequence below follows: 0 sec: The relief valve 300 opens 1 sec: The inlet valve 12 opens. At that moment substantially atmospheric pressure prevails in the dust collector. 1.3 sec: The inlet valve 12 closes 3 sec: The relief valve 300 closes.