GB2117090A - An improved pressurized fluid jetting device in a color sorting apparatus - Google Patents

Abstract

A pressurized fluid jetting device (1) for use in color sorting granular materials by the blowing action of a pressurized fluid has a cylindrical member (13), a cap member (11) detachably secured thereto, a valve seat member (19), pressure receiving plate (25) fixed therebetween, and a valve plate (22) movable between the valve seat member (19) and the pressure receiving plate (25). The cylindrical member (13) has an internal cavity defining a fluid passage (14) and a solenoid means (15) adapted to be selectively energized in accordance with the state of detection of grains of different colors. Usually the valve plate (22) is pressed onto the valve seat member (19) to shut off the flow of the fluid but, as the solenoid means (15) is energized, the valve plate is strongly attracted to strike the pressure receiving plate (25) to cause a rapid wear of the latter. The pressure receiving plate (25) can be renewed easily because it is formed as a body separate from the cylindrical member (13). <IMAGE>

Description

SPECIFICATION An improved pressurized fluid jetting device in a color sorting apparatus The present invention relates to a color sorting apparatus for sorting granular materiais according to their colours and, more particularly, to an improvement in a pressurized fluid jetting device for use in a sorting apparatus of the kind described.

A color sorting apparatus adapted to sort granular materials of different colors according to their colors is known. This conventional apparatus incorporates a device for jetting a pressurized fluid to selectively blow the sorted objects. The pressurized fluid jetting device incorporates a cup-shaped cylindrical main body in which is provided a passage for the pressurized fluid and a solenoid means surrounding the passage. A pressure receiving surface is constituted by the bottom wall of the main body provided with a plurality of vent holes. Also, a cap member provided with a valve seat member therein is detachably screwed to the main body. A valve plate is loosely fitted in a guide air passage provided in the valve seat member.This valve plate is adapted to be moved in the axial direction of the device by the balance of force between the magnetic attracting force of the solenoid means and the force produced by the pressurized fluid in the fluid passage to make contact either with the pressure receiving surface or the valve seat. In this type of color sorting apparatus, the frequency of operation of the pressurized fluid jetting device is extremely high, and the magnetic attracting force of the solenoid means is very large, so that the pressure receiving surface struck by the valve plate is worn rapidly. The wearing down of the pressure receiving surface causes a change in the stroke of the valve plate which in turn disorders the action of the device for jetting the pressurized fluid, resulting in a serious deterioration of sorting performance of the sorting apparatus.To recover the normal sorting performance, it is necessary to renew the worn down pressure receiving surface frequentiy. The work for renewing the part is extremely complicated and troublesome particularly when the sorting apparatus is arranged and constructed with a plurality of sorting units side by side. In addition, considerable money, labour and time is required for the renewal of the main body of the pressurized fluid jetting device.

Accordingly, the present invention aims as its major object at overcoming the above-described problem of the prior art.

To this end, according to the invention, there is provided a pressurized fluid jetting device for color sorting apparatus, having a cup-shaped cylindrical body accommodating a fluid passage and a solenoid means, the cup-shaped cylindrical body having a bottom wall provided with vent holes and constituting a pressure receiving surface, a cap member provided therein with a valve seat member and detachably secured to the cupshaped cylindrical body; and a valve plate loosely fitted in a guide passage formed in the valve seat member; characterized in that the body of the pressurized fluid jetting device has a cylindrical wall portion and a pressure receiving plate portion having vent holes, the pressure receiving plate portion being formed as a body separate from the cylindrical wall portion and detachably secured to one end of said cylindrical wall portion.

The above and other features will be apparent in the following description of a preferred embodiment given with reference to the accompanying drawings, in which: Fig. 1 is a sectional view of a photoelectric sorting chamber of a color sorting apparatus; Fig. 2 is a sectional side elevational view of a conventional pressurized fluid jetting apparatus; Fig. 3 is a sectional side elevational view of a pressurized fluid jetting device in accordance with an embodiment of the invention; and Fig. 4 is an exploded perspective view of a pressurized fluid jetting device as shown in Fig. 3.

Before turning to the description of the embodiment, an explanation will be made here as to the general construction of a color sorting apparatus in which the pressurized fluid jetting device of the invention is incorporated.

Referring to Fig. 1, granular material, for example, grain containing grains of different colors, are supplied into a photoelectric sorting chamber 2 through a grain chute 3 mounted on the sorting chamber 2. The grains flow in the sorting chamber 2 in a linear form along a predetermined path A. A photo-electric chamber 4 is disposed at each side of the photoelectric sorting chamber 2. Each photoelectric chamber 4 accommodates a light emitting element 5, a light receiving element 7 and a reference color plate 6 all disposed as shown in the Figure. In operation, the light is applied by the light sources 5 to the grain flow flowing along the path A, and the difference between the amount of light reflected or transmitted by the grain flow and the amount of light coming from the reference color plate 6 is detected by the light receiving element 7 in each photoelectric chamber 4.The light receiving element produces, upon detection of the presence of grains of a different color, a detection signal for actuating the pressurized fluid jetting device 1 so that a pressurized fluid, which is in this case compressed air, is jetted from a nozzle 10 of the jetting device 1 to blow the grain particles of the different color away from the predetermined path A of flow of the grains. The grain particles of the different color thus blown away from the path A are collected at the bottom of the sorting chamber 2 and are discharged through a discharge port 8.

On the other hand, the grain particles of ordinary color are allowed to flow along the path A and are discharged to the outside of the sorting apparatus through a grain collecting sleeve 9. Thus, the grains having colors different from that of ordinarily coloured grain are separated and taken away from the latter.

As will be understood from the foregoing description, the pressurized fluid jetting device 1 is operated very frequently, and, in addition, very abruptly at each time of detection of the grain of a different color.

Fig. 2 shows a typical conventional pressurized fluid jetting device 1 A used in the color sorting apparatus of the kind described above. This conventional jetting device 1 A has a main body 1 2A constituted by a cup-shaped cylindrical member 1 3A in which is defined a fluid passage 14A surrounded by a solenoid means 15A. The bottom wall of the cup-shaped cylindrical member 13A, provided with a plurality of vent holes 23A, constitutes a pressure receiving surface 25A. A cap member 1 1A having a valve seat member 1 9A therein is fixed by screwing to the outlet side end of the main body 12A with an "0" ring 8A compressed between the pressure receiving surface 25A and the valve seat member 19A. A valve plate 22A is loosely fitted in a guide passage 20Aformed in the valve seat member 1 9A.The fluid passage 1 4A is connected to a source of compressed air so that the valve plate 22A is normally pressed against the inner surface of the valve seat member 19A, as illustrated, by the force produced by the pressure of compressed air.

However, as the grain particles of a different color are detected, the solenoid means 15A is energized through lead wires 27A to produce a magnetic attracting force which acts to attract the valve plate 25A onto the pressure receiving surface 25A, thereby to permit the compressed air to be jetted from the nozzle 10 (See Fig. 1) attached to the cap member 11. Thus, the valve plate 22 is adapted to be moved reciprocatingly in the axial direction, and the frequency of operation of the same is considerable. In addition, the valve plate 22 strikes the pressure receiving surface sharply due to the large force of attraction exerted by the solenoid means 15A.In consequence, the pressure receiving surface 25A is worn down rapidly to increase the stroke of the valve plate 22A so that the jetting action of the nozzle 10 of the device 1 A for jeeting the compressed air deteriorates and seriously lowers the sorting performance. In order to recover the required sorting performance by eliminating the trouble attributable to the wearing down of the pressure receiving surface, it is necessary to renew the main body 1 2A of the device as a whole, requiring much money and labour as stated before.

This problem of the prior art, however, is overcome by the present invention, as will be realized from the following description of the preferred embodiment of the invention.

Figs. 3 and 4 show an embodiment of the pressurized fluid jetting device in accordance with a preferred embodiment of the invention. The pressurized fluid jetting device generally designated by the reference numeral 1 has a nozzle 10 (See Fig. 1), cap member 11 and a main body 12, although the nozzle 10 is omitted from Figs. 3 and 4.

The main body 12 has a cylindrical member 13 in which is defined a fluid passage 14 surrounded by a solenoid means 15. A fluid chamber 16 is formed at the outlet side of the fluid passage 14.

The cap member 11 has a cylindrical member 17 with a frusto-conical head portion, receiving at its central portion a valve seat member 19 provided with a plurality of small through holes 18 disposed in a circle. A guide passage 20 is formed in the valve seat member 19. The cylindrical member 17 is internally threaded at its front and rear end portions. A nozzle 10 (See Fig. 1) and the outlet end of the main body 12 are detachably fixed by screwing onto the front and rear end portions of the cylindrical member 17, respectively. An annular valve plate 22 is provided with a central through hole 21. A disc-shaped pressure receiving plate 25, which is a body separate from the main body 12, is provided with a central through hole 24 of a diameter greater than that of the aforementioned fluid passage 14.The valve plate 22 loosely fits in the guide passage 20 formed in the valve seat member 19 mounted in the cap member 11. After adhering the pressure receiving member 25 to the outlet side end of the main body 12, the cap member 11 is screwed onto the outlet side end of the main body 12 with an "O" ring 8 compressed between the valve seat member 1 9 and the pressure receiving plate 25. In consequence, the cap member 11 is assembled with the main body 12 while pressing the pressure receiving plate 25 by means of a flange 26 provided on the valve seat member 19. At the same time, the nozzle 10 is screwed onto the end of the cap member thus completing the assembling of the pressurized fluid jetting device 1.

In the assembled state of the device 1, the pressure-receiving plate 25 partially covers the fluid chamber 1 6 of the main body 12 with the vent holes 23 thereof communicating with the fluid chamber 1 6.

In operation, since the fluid passage 1 4 is connected to a source of compressed air, the valve plate 22 loosely fitting in the guide passage 20 in the valve seat member 1 9 is normally pressed against the inner surface of the valve seat member 1 9 as shown in Fig. 3 by the action of the compressed air coming from the source of compressed air, thereby to close the small through holes 18, so that the compressed air is not supplied to the nozzle 10.

As stated before, when the light receiving element 7 in the photoelectric sorting chamber 2 detects the grain particles of a different color, the element 7 produces a detection signal by which the solenoid means 1 5 is energized through lead wires 27. In consequence, the valve plate 22 loosely fitting in the guide passage 20 is attracted towards the pressure receiving plate 25 to make an impacting contact therewith, by the electromagnetic attracting force produced by the solenoid means 1 5, so that the plurality of small through holes 1 8 in the valve seat member 1 9 are opened.As a result, a part of the compressed air in the fluid passage 14 flows into the inner peripheral portion of the valve plate 22 via the through hole 24 of the pressure receiving plate 25 and the through hole 21 of the valve plate 22 and further into the small through holes 18 in the valve seat member 19, while the other part of the compressed air in the fluid passage 14 flows into the guide passage 20 via the fluid chamber 16 and the vent holes 23 of the pressure receiving plate 25 and further into the small through holes 18 in the valve seat member 19 via the space around the valve plate 22. The air then is jetted from the nozzle 10 attached to the cap member 11 to blow the detected grain particles of the different color away from the predetermined path of the grain to separate the grain particles of the different color from ordinary grains.

As the detection signal from the light receiving element 7 is extinguished, the solenoid means 1 5 is de-energized so that the valve plate 22, which has been attracted into contact with the pressure receiving plate 25, is moved by the pressure of the compressed air flowing in the fluid passage into contact with the inner surface of the valve seat member 19 to close the small holes 18 in the latter thereby to shut off the flow of compressed air from the nozzle 10.This operation of the pressurized fluid jetting device 1 is conducted instantaneously and at a high frequency of repetition, so that the contact surface of the pressure receiving plate 25 is rapidly worn down due to the striking by the valve plate 22 caused by the large electromagnetic attracting force exerted by the solenoid means 1 5. In consequence, the stroke of the valve plate 22 is increased and the jetting action of the device is disabled. In such a case, the color sorting apparatus is stopped without delay, for the renewal of the pressure receiving plate 25. This can be done simply by unscrewing the cap member 11 from the body of the pressurized fluid jetting device 1. By so doing, the pressure receiving plate 25 becomes accessible and can be replaced easily with new one.In this state, it is also possible to inspect the valve plate 22 and the valve seat member 19 in the cap member 11. If necessary the valve plate 22 and the valve seat member 1 9 are renewed. After fitting these parts in the correct places, the cap member 11 is screwed onto the main body 12 to assemble all parts as explained before, so that the pressurized fluid jetting device 1 is completely repaired and is ready to perform the blowing sorting operation at high accuracy.

In contrast to the conventional pressurized fluid jetting device in which the pressure receiving plate is constituted by the bottom wall of a cup-shaped cylindrical member having a plurality of vent holes, the pressure receiving plate in the device of the invention is formed as a member separate from the cylindrical member constituting the main body of the device and is detachably secured to the cylindrical member by quite a simple means. It is, therefore, possible to inspect and, if necessary, renew various parts which are liable to be worn down by the repeated opening and closing action of the valve plate, e.g. pressure receiving plate, valve plate itself, valve seat member and so forth, in quite an easy manner. In addition, the pressurized fluid jetting device of the invention has quite a simple construction and the parts thereof are easy to fabricate, so that the cost of production is lowered substantially. Also, it is possible to improve the rate of operation of the color sorting apparatus while maintaining a high sorting performance.

Claims (2)

1. A pressurized fluid jetting device for color sorting apparatus, having a cup-shaped cylindrical body accommodating a fluid passage and a solenoid means, said cup-shaped cylindrical body having a bottom wall provided with vent holes and constituting a pressure receiving surface, a cap member provided therein with a valve seat member and detachably secured to said cupshaped cylindrical body; and a valve plate loosely fitted in a guide passage formed in said valve seat member; characterized in that said body of said pressurized fluid jetting device has a cylindrical wall portion and a pressure receiving plate portion having vent holes, the pressure receiving plate portion being formed as a body separate from said cylindrical wall portion and detachably secured to one end of said cylindrical wall portion.

2. A pressurized fluid jetting device substantially as described with reference to Figures 3 and 4 of the accompanying drawings.