GB2088694A

GB2088694A - Pneumatic tobacco transport

Info

Publication number: GB2088694A
Application number: GB8136214A
Authority: GB
Original assignee: Molins Ltd
Current assignee: Mpac Group PLC
Priority date: 1980-12-03
Filing date: 1981-12-01
Publication date: 1982-06-16

Abstract

Tobacco is transported pneumatically, e.g. to a cigarette making machine, through a pipe having means for deflecting the tobacco upwards, within a generally horizontal pipe section, to restore the tobacco to an airborne state after it has dropped through gravity to the bottom of the pipe. The deflection of the tobacco may be achieved by one or more inserts in the pipe providing a ramp 4, a plateau 5 and a downwardly tapering trailing surface 6. Alternatively, deflection may be achieved by one or more tubes 8 (Fig 3) which syphon off air from an upper region of the pipe and reintroduce it from below the pipe, into a region of the pipe having a reduced cross-sectional area. <IMAGE>

Description

SPECIFICATION Pneumatic tobacco transport The present invention is concerned with the pneumatic transport of tobacco to cigarette making machines; that is to say, cut tobacco ready for forming into cigarettes.

The pneumatic transport of particulate material is generally well known. In the tobacco industry tobacco is often fed pneumatically from a communal source to a plurality of cigarette making machines along long pipes through which air flow is produced by suction at the delivery ends of the pipes. However, problems occur if the pipes have long horizontal sections. Tobacco tends to fall, under the effects of gravity, to the bottom of such pipes thereby becoming separated from the main air stream so that transport is less efficient and the tobacco can become damaged. To counteract this effect, high air velocities have customarily been used, requiring higher suction pressures for long pipes. However, high suction pressures cause sealing problems at the delivery ends of the pipes, i.e. at the cigarette making machines.

According to one aspect of the present invention there is provided a method of pneumatically transporting tobacco along an elongate generally horizontal hollow member, the method including the step of deflecting the tobacco upwards in the hollow member at one or more positions along the hollow member to keep the tobacco airborne.

For convenience the hollow member will be referred to as a "pipe", though it may in practice comprise a series of separate pipes connected end to end by devices including the deflecting means.

According to a second aspect of the present invention, a pipe for pneumatically transporting tobacco in a generally horizontal direction includes at least one deflecting means arranged to deflect upwards tobacco transported through the pipe, the portion of the pipe through which the tobacco is deflected having a reduced internal cross-sectional area so as to increase the speed of the air along that portion of the pipe, thus accelerating the tobacco.

For a given length of pipe, this invention enables tobacco or similar materials to be pneumatically transported with a lower suction source. This is particularly useful for relatively long pipes, e.g. longer than 50 metres.

According to a first embodiment of the invention the particulate material is deflected by means of ramps spaced in the direction of material flow, in the lower section of the pipe.

The ramps themselves preferably have plateaus forming portions of the pipe of reduced cross-section.

According to a second embodiment of the invention the particulate material is deflected by syphoning air from the upper portion of the pipe and re-directing this syphoned air into the lower portion of the pipe in a direction having an upwards component so as to lift tobacco from the lower portion of the pipe.

This may be effected by means of one or more narrow tubes opening into the pipe in the upper position thereof at one position and opening into the lower portion of the pipe at a position downstream of said one position. In this embodiment an inverted ramp may be provided in the upper portion of the pipe to co-operate with the syphoning tube or tubes to assist in controlling the deflection of the material and to accelerate the air.

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made to the accompanying drawings, in which: Figure 1 shows a first embodiment of the present invention; Figures 2A to 2Eare schematic illustrations of cross-sections taken along lines AA to EE in Fig. 1 when the apparatus of Fig. 1 is in use; Figure 3 illustrates a second embodiment of the invention and is a section on the line Ill-Ill in Fig. 5; Figure 4 is a bottom plan view of the apparatus of Fig. 3; and Figure 5 is a cross-section on the line V-V in Fig. 3.

Fig. 1 shows a pipe in which tobacco is transported pneumatically in the direction of the arrow 2 from a tobacco store (not shown) to a cigarette making machine (not shown). A suction fan is connected to the cigarette machine end of the pipe to draw the air through the pipe.

A ramp 3 rises from the bottom of the pipe 1, presenting a concave face 4 to the tobacco and air stream, starting with a smooth transition from the horizontal bottom surface of the pipe. Ramp 3 has a plateau portion 5 downstream of the concave face 4, and a portion 6 which tapers back towards the bottom of the pipe 1, e.g. at an angle of about 10 or less.

As tobacco is carried along the pipe 1 it tends to accumulate, under the effect of gravity, on the bottom of the pipe 1, as shown in Fig. 2A where the tobacco material is indicated by reference numeral 7. As it moves further along the pipe 1 it encounters the arcuate sloping face 4 of ramp 3 (giving 6g centrifugal force for a 20' arc), which causes it to be carried upwards as shown in Fig. 2B.

The tobacco then reaches the plateau portion 5 as shown in Fig. 2C and is carried upwards by its own momentum into the upper portion of the pipe 1, as shown in Fig. 2D, even though the ramp slopes away from the upper part of the pipe 1 in ramp portion 6. Hence, after the tobacco has passed over ramp 3 it is again airborne as shown in Fig. 2E and is carried more efficiently by the air stream. A plurality of these ramps may be provided in a long pipe.

The reduction in the internal cross-section of the pipe in the region of the plateau results in an increased air velocity in that region (and in the approach to that region) which accelerates and assists in deflecting the tobacco.

Fig. 3 shows a second embodiment of the invention. Tobacco is carried along pipe 1 in the direction of arrow 2 by a moving air stream. A pair of narrow tubes 8 (see Fig. 4) have inlet ends 9 in the upper portions of pipe 1 and outlet ends 10 in the lower portion of pipe 1. By means of narrow tubes 8 air is syphoned off as indicated by arrows 11 in Fig. 3, into the tube 8 from the upper portion of pipe 1 and is directed into the lower portion of pipe 1 in such a direction as to lift tobacco which has accumulated on the bottom of pipe 1. Inverted ramps 1 2 are provided in the upper portion of pipe 1 to aid this process. It can be seen from Fig. 5 that in the region of inlet ends 9, the pipe 1 has a generally flat top; this enables the tubes 8 to collect air more efficiently.In regions remote from the ends 9 of the ducts, the pipe 1 has a substantially circular cross-section.

As in Fig. 1, the ramp increases the air velocity since it progressively reduces the internal cross-section of the pipe. In this example, the increased velocity (and consequently reduced pressure) has a venturi effect which draws more air into the tubes 8 and thus assists the upward deflection of the tobacco owing to the increased velocity of the air leaving the tubes.

The second embodiment illustrated in Figs. 3 to 5, is more effective in deflecting the tobacco, but is more expensive to put into practice.

By way of example, the following comparison can be made between a conventional pipe system and a system according to this invention. In a typical conventional system, tobacco may be conveyed in a pipe, 4 inch diameter (10 cms), at a velocity of approximately 3600 feet/min (1100 metres/min). Using a pipe of same diameter in accordance with this invention, and with this invention, and with deflecting means approximately every 8G feet (24 metres), we calculate that the air velocity can be reduced to approximately 2400 feet/ min (730 metres/min). This allows the suction pressure at the delivery end of the pipe to be reduced by approximately 50%, and consequently the power consumed is reduced by approximately 66%.

The plateau portion 5 and downwardly tapering portion 6 of the deflecting means shown in Fig. 1 reduce the pressure drop, compared with a ramp member having only the deflecting surface 4 followed by an abrupt step down.

Claims

1. A method of pneumatically transporting tobacco along an elongate generally horizontal hollow member, including the step of deflecting the tobacco upwards in the hollow member at one or more positions along the hollow member to keep the tobacco airborne.

2. A pipe for pneumatically transporting tobacco in a generally horizontal direction, including at least one deflecting means arranged to deflect upwards tobacco transported through the pipe, the portion of the pipe through which the tobacco is deflected having a reduced internal cross-sectional area so as to increase the speed of air along that portion of the pipe, thus accelerating the tobacco.

3. A pipe according to claim 2 in which the deflecting means comprises a ramp in the lower section of the pipe.

4. A pipe according to claim 3 in which the deflecting surface of the ramp is concave in longitudinal section.

5. A pipe according to claim 4 in which the deflecting surface of the ramp is followed by a portion which tapers downwards back towards the bottom of the pipe.

6. A pipe according to claim 5 in which the ramp includes a plateau portion between the deflecting surface and the downwardly tapering portion.

7. A pipe according to claim 2 in which the deflecting means comprises means for syphoning away air from the upper portion of the pipe and for re-directing the syphoned air into the lower portion of the pipe in a direction having an upwards component so as to lift tobacco from the lower portion of the pipe.

8. A pipe according to claim 7 in which the deflecting means comprises one or more narrow tubes opening into the pipe in the upper position thereof at one position and opening into the lower portion of the pipe at a position downstream of said one position.

9. A pipe according to claim 8 including an inverted ramp in the upper portion of the pipe to co-operate with the syphoning tube or tubes to assist in controlling the deflection of the material and to accelerate the air.

10. Apparatus for conveying tobacco from a communal source of tobacco to a number of cigarette making machines via pipes according to claim 1 having lengths at least of the order of 50 metres, the air flow through the pipes being adapted to be at a velocity of approximately 730 metres/minute, and the deflecting means being positioned in the pipes at intervals of approximately 24 metres.

11. A method according to claim 1 and substantially in accordance with any one of the examples described with reference to the accompanying drawings.

1 2. Apparatus according to claim 2 and substantially in accordance with any one of the examples described with reference to the accompanying drawings.

1 3. The subject matter of any preceding claim (ignoring any dependency of one claim on another) considered separately or in combination with the subject matter of any one or more of the other claims (again ignoring dependency).