The present invention relates to an air flow adjusting apparatus which adjusts the flow rate of air to be discharged or taken in from an air source to a load.
A conventional air flow adjusting apparatus shown in Japanese Utility Model Publication No. 8-5806 comprises an air supply passage 101 through which suction air is supplied to a sheet feed device, a valve chamber 102 arranged in the air supply passage 101, and a butterfly valve 104 which is arranged in the valve chamber 102 and pivots about a support shaft 103, as shown in
The air flow adjusting apparatus shown in Japanese Utility Model Laid-Open No. 59-162552 comprises an air blowing passage and air suction passage respectively connected to the discharge port and suction port of an air pump, and switching valves respectively arranged between the air blowing passage and a suction wheel and between the air suction passage and a suction wheel. Each switching valve has a notch with a semilunar section. When the switching valve pivots, the quantity of suction air or discharge air to the suction wheel is adjusted through the notch.
In the conventional air flow adjusting apparatuses described above, when the opening angle θ of the valve body is small, the quantity of air passing through the valve body is relatively small for a change in opening angle θ of the valve body. When the opening angle θ of the valve body is large, the quantity of air relatively increases for a change in opening angle θ of the valve body. Thus, the relationship between the opening angle of the valve body and the pressure of air to be supplied is not constant, as shown in
In the conventional air flow adjusting apparatuses described above, when the air passage is entirely shielded by the valve body, the pressure of air supplied from an air source increases the internal pressure between the air source and valve body. In this state, when the valve body starts to open the air passage, the quantity of air passing through the valve body temporarily reaches a flow rate equal to or more than that corresponding to the opening angle of the valve body, and the pressure of air to be supplied fluctuates largely. Therefore, in the conventional air flow adjusting apparatuses described above, it is difficult to adjust the flow rate of air highly accurately.
It is an object of the present invention to provide an air flow adjusting apparatus which facilitates air flow adjustment highly accurately.
In order to achieve the above object, according to the present invention, there is provided an air flow adjusting apparatus comprising a first air passage to be connected to a load, a second air passage to be connected to an atmosphere, a third air passage which is to be connected to an air source and branches to be connected to the first air passage and the second air passage, and opening/closing means for opening/closing a first connecting portion between the first air passage and the third air passage and a second connecting portion between the second air passage and the third air passage in an interlocked manner, wherein the opening/closing means opens/closes the first connecting portion and the second connecting portion with a sum of an opening area of the first connecting portion and an opening area of the second connecting portion being always set constant.
An air flow adjusting apparatus according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 6. This embodiment is directed to an air flow adjusting apparatus applied to a sheet-fed offset rotary printing press.
Referring to
A plurality of gripper bars 5 each comprising a gripper pad and gripper pad shaft are supported between the pair of delivery chains 4 at predetermined intervals in the direction of the arrow A. A plurality of gripper devices 6 each comprising a gripper and gripper pad line up on each gripper bar 5 in the axial direction. The gripper devices 6 grip a paper sheet 7 from the gripper devices 6 of the final cylinder of a printing unit arranged upstream of the delivery unit 1 in the sheet convey direction, and conveys the paper sheet 7 as the delivery chains 4 travel. The paper sheet 7 conveyed by the gripper devices 6 is released when the grippers of the gripper devices 6 are opened and closed with respect to the gripper pads by sheet release cams (not shown), and is dropped on a pile board 8 and stacked there.
Three paper guides 9A, 9B, and 9C divided in the sheet convey direction are provided with air suction ducts (not shown) which are connected to a dust collector 10 through hoses 11a, 11b, 11c, and 11d. A spray pipe 12 supported between the pair of frames 2 is disposed on an upright portion extending obliquely upward from the starting end of the delivery chains 4. The spray pipe 12 is connected to an air supply source (not shown). The spray pipe 12 has a plurality of spray nozzles 13 which line up, and blows powder to the paper sheet 7 under conveyance by the delivery chains 4.
The spray pipe 12 and spray nozzles 13 are covered with a box-like cover 14 which is supported between the pair of frames 2 and has one open face opposing the paper sheet 7 under conveyance. The two, front and rear wall surfaces of the cover 14 are provided with brushes 15 which come into slidable contact with the traveling gripper bars 5 and gripper devices 6. The powder discharged from the spray nozzles 13 is blown to the printed surface of the paper sheet 7 under conveyance in a space surrounded by the cover 14 and brushes 15.
A blowing device 16 supported between the pair of frames 2 is arranged above the sheet convey path downstream of the spray nozzles 13 in the sheet convey direction, and blows air to the printed surface of the paper sheet 7 under conveyance to be substantially parallel to the printed surface of the paper sheet 7 and toward the upstream in the sheet convey direction. An air suction duct 17 supported between the pair of frames 2 is disposed above the sheet convey path located at substantially the intermediate portion between the spray nozzles 13 and blowing device 16. The air suction duct 17 takes in excessive powder blown from the spray nozzles 13 and leaking from the space surrounded by the cover 14 and brushes 15 together with air blown from the blowing device 16. The air suction duct 17 is connected to a blower 19, serving as an air source in the dust collector 10, through a hose 11e and air flow adjusting devices 20 (to be described later). A porous plate 18 having many suction holes is attached to the air suction duct 17 to face upstream in the sheet convey direction.
In this arrangement, after the paper sheet 7 is gripping-changed from the last cylinder of the printing unit to the gripper devices 6 and conveyed by the delivery chains 4, the powder discharged from the spray nozzles 13 is blown to the printed surface of the paper sheet 7. Therefore, at a sheet delivery unit as the convey terminal end, setoff or so-called blocking does not occur between paper sheets 7 stacked on the pile board 8. The excessive powder blown from the spray nozzles 13 and leaking from the space surrounded by the cover 14 and brushes 15 is regulated from flowing downstream in the sheet convey direction with air blown from the blowing device 16, and is taken in by the air suction duct 17.
The air flow adjusting devices 20 will be described with reference to
As shown in
The flow adjusting plate 22 (opening/closing means) is supported to be movable in a direction (direction of arrows B-C) perpendicular to the air channels in the respective air passages so as to block the first and second connecting portions 27 and 28. A slit 23 is formed in the valve cage 21. The slit 23 extends in the direction of the arrows B-C to correspond to the first and second connecting portions 27 and 28 and opens to one end face of the valve cage box 21. The flow adjusting plate 22 is supported to be movable in the slit 23 in the direction of the arrows B-C.
The first air passage 24 is formed in the valve cage 21 in a direction (direction of arrows D-E) perpendicular to the slit 23, and connected to an opening 24a which opens to one side surface (on the side of the direction of the arrow E) of the valve cage 21. The second air passage 25 is formed in the valve cage 21 in a direction (direction of the arrows D-E) perpendicular to the slit 23, and connected to an opening 25a which opens to one side surface (on the side of the direction of the arrow E) of the valve cage 21. The first and second first connecting portions 27 and 28 respectively connected to the first and second air passages 24 and 25 are formed at the same position in the widthwise direction (direction of arrows F-G) in the flow adjusting plate 22, as shown in
A third air passage 26 is formed in the valve cage 21 to extend in the direction of the arrows B-C. One end 26a of the air passage 26 extends to the first connecting portion 27 and communicates with the first air passage 24 through the first connecting portion 27. The other end 26b of the third air passage 26 extends to the second connecting portion 28 and communicates with the second air passage 25 through the second connecting portion 28. An opening 26c is formed in that side surface of the valve cage 21 which is opposite (the direction of the arrow D) to the first and second air passages 24 and 25. The opening 26c is connected to the blower 19 through a hose 30. Namely, the third air passage 26 starting from the opening 26c branches in the valve cage 21 so as to be connected to the first and second connecting portions 27 and 28.
As shown in
Regarding flow adjustment, the flow adjusting plate 22 is accommodated in the slit 23 of the valve cage 21. At this time, when the second communication window 32 coincides with the second connecting portion 28, as shown in
When the flow adjusting plate 22 further moves in the direction of the arrow B, as shown in
Referring back to
A method of adjusting the flow rate of suction air to be supplied to the respective air suction ducts of the paper guides 9A, 9B, and 9C and to the air suction duct 17 in the air flow adjusting apparatus with the above arrangement will be described. The first connecting portion 27 of the air flow adjusting device 20 is entirely shielded by the flow adjusting plate 22 in advance, as shown in
In this state, the switch of the blower 19 of the dust collector 10 is turned on. In this case, the air suction duct 17 does not communicate with the third air passage 26, and supply of suction air to the air suction duct 17 is stopped. Thus, the pressure of the suction air to be supplied to the air suction duct 17 is “0”. Subsequently, when the manipulation lever 36 of the air flow adjusting device 20 pivots counterclockwise about the shaft 37 as the center, the flow adjusting plate 22 moves in the direction of the arrow B, as shown in
Therefore, the suction air supplied from the blower 19 to the third air passage 26 partly passes through the first connecting portion 27 and is supplied to the air suction duct 17 as the negative pressure. The remaining suction air is taken in from the atmosphere through the second connecting portion 28. To maximize the supply quantity of the suction air to the air suction duct 17, the air flow adjusting plate 22 is moved further in the direction of the arrow B, as shown in
In air flow adjustment, since the sum of the opening area of the first connecting portion 27 and the opening area of the second connecting portion 28 is always constant, the sum of the quantity of air passing through the first connecting portion 27 and the quantity of air passing through the second connecting portion 28 can always be set constant. Hence, the internal pressure between the blower 19 and the first connecting portion 27 can always be set constant. Even if the opening area of the first connecting portion 27 is “0”, the internal pressure does not increase. Therefore, the influence of the internal pressure, which occurs conventionally when the first connecting portion 27 starts to open, can be eliminated to eliminate large air pressure fluctuation. Thus, air flow can be adjusted highly accurately.
Since the shapes of the first and second communication windows 31 and 32 and the respective sectional shapes of the first and second connecting portions 27 and 28 are rectangular, the relationship (ratio) between the moving amount of the flow adjusting plate 22 in the direction of the arrows B-C and the change amount of the opening area of the first connecting portion 27 is constant. Therefore, the ratio of the moving amount of the flow adjusting plate 22 to the pressure of air in the air suction duct 17 connected to the first connecting portion 27 becomes constant, as shown in
The second embodiment of the present invention will be described with reference to
The sizes of the first and second communication windows 131 and 132 in a direction of arrows B-C are set to be equal to the diameters of the first and second connecting portions 127 and 128. In the same manner as in the first embodiment, an interval L between one side in the direction of the arrow B of the first communication window 131 and one side in the direction of the arrow B of the second communication window 132 is set to be equal to an interval L between the first and second connecting portions 127 and 128. Hence, in the same manner as in the first embodiment, the sum of the opening area of the first connecting portion 127 obtained by the first communication window 131 and the opening area of the second connecting portion 128 obtained by the second communication window 132 is always constant to follow the movement of the flow adjusting plate 122 in the direction of the arrows B-C.
According to this embodiment, the first and second communication windows 131 and 132 are formed as ellipses having major axes in the direction of the arrows F-G. Even when the positions of the valve cage 121 and flow adjusting plate 122 shift in the direction of the arrows F-G, the opening areas of the first and second connecting portions 127 and 128 do not become smaller than the regular opening areas. Thus, the supply quantity of suction air to the suction duct does not become smaller than a predetermined supply quantity, and an accurate quantity of air can be supplied.
The third embodiment of the present invention will be described with reference to
The first and third air passages 41 and 43 are arranged in a first hollow body 44 serving as a valve cage. A first connecting portion 45 between the first and third air passages 41 and 43 is shielded or opened by a first flow adjusting plate 47 which is driven by a first motor 46 to move in the radial direction (vertical direction in
An air flow rate input unit 52 to which the value of the suction air quantity to be supplied to the air suction duct 17 is connected to a controller 53. The controller 53 controls the driving directions and driving times of the first and second motors 46 and 50 on the basis of an input value input to the air flow rate input unit 52. More specifically, the controller 53 controls the first and second motors 46 and 50 to move the first and second flow adjusting plates 47 and 48 such that the sum of the opening area of the first connecting portion 45 obtained by the first flow adjusting plate 47 and the opening area of the second communication hole 49 obtained by the second flow adjusting plate 51 is always constant.
According to this embodiment, since the relationship (ratio) between the moving amounts of the first and second flow adjusting plates 47 and 51 and a change in pressure of air in the air suction duct 17 is always constant, the air flow adjusting apparatus 40 can perform highly accurate adjustment easily.
In the respective embodiments described above, the air flow adjusting apparatus is applied to a dust collector which removes paper dust, powder, dust, or the like by suction drawing. The air flow adjusting apparatus can naturally have applications other than the dust collector. For example, the air flow adjusting apparatus can be applied to a suction wheel which grips the trailing edge of a paper sheet released from gripper devices 6, thus adjusting the quantity of suction air. The air flow adjusting apparatus can also be applied to an air blower, leveling foot, or the like in a sheet feed device or an air blowing device which blows air from a nozzle so as to bring a paper sheet into tight contact with the outer surface of a cylinder, thus adjusting the blowing air quantity.
Although the air source has been exemplified by a blower which supplies suction air, the air source can be a discharge pump which supplies discharge air. Various design change can be made in the air supply. Although the sectional shapes of the first and second connecting portions 27 and 28 and the shapes of the first and second communication windows 31 and 32 are both square in the first embodiment, they may be rectangular. Only the shapes of the first and second communication windows 31 and 32 may be rectangular.
As has been described above, according to the present invention, since the sum of the opening areas of the first and second connecting portions is always constant, the sum of the quantity of air passing through the first connecting portion and the quantity of air passing through the second connecting portion can always be set constant. Hence, the internal pressure between the blower and the first connecting portion can always be set constant. Even if the opening area of the first connecting portion is “0”, the internal pressure does not increase. Therefore, the influence of the internal pressure, which occurs conventionally when the first connecting portion starts to open, can be eliminated, so that the air flow adjusting apparatus can perform highly accurate air flow adjustment.
Number | Date | Country | Kind |
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115456/2005 | Apr 2005 | JP | national |