(19) |
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(11) |
EP 0 972 435 A2 |
(12) |
EUROPEAN PATENT APPLICATION |
(43) |
Date of publication: |
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19.01.2000 Bulletin 2000/03 |
(22) |
Date of filing: 11.05.1999 |
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(84) |
Designated Contracting States: |
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AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE |
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Designated Extension States: |
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AL LT LV MK RO SI |
(30) |
Priority: |
13.05.1998 GB 9810097
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(71) |
Applicant: Hartley Industries Limited |
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Sheffield S11 9UZ (GB) |
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(72) |
Inventor: |
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- Yates, Adam John
Cramlington,
Northumberland NE23 9DH (GB)
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(74) |
Representative: Long, Edward Anthony et al |
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Hulse & Co,
St. James House, 8th Floor,
Vicar Lane Sheffield S1 2EX Sheffield S1 2EX (GB) |
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(57) A soil sifta, eg a soil sifting device, has a body figure 1 which is an inclined
mesh drum A, with open end upper most which is loaded with garden material to be sifted.
The bottom of the drum is closed except for a helical labyrinth figure 2. On rotating
the drum in one direction the material is agitated and separated through the mesh
rolling up and over the step shown in the helical back plate figure 4. Sifted soil
then falls to a barrow or container below the drum. Larger debris is expelled from
the bottom of A when the rotation is reversed. Debris falls through the labyrinth
formed by the helical back plate figure 1,2,3,4. The inclined drum is supported by a portable frame D, to which is attached the motor
housing or crank handle C.
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[0001] The invention relates to a soil sifting device.
[0002] Gardeners would traditionally prepare the soil for cultivation by removing grass
first and then turn over the earth breaking the compacted earth into smaller pieces.
[0003] The action of breaking these clods down allows the soil to be permeable to both air
and water for healthy growth.
As a finishing operation the gardener may use a garden riddle to remove stones and
weeds.
This riddle is a hand held tray made of wood and a perforated material that is shaken
back and forth, this has the effect of loosening the soil, so the rocks and weeds
are left in the tray.
This is a back-breaking and labour intensive job.
[0004] According to the present invention the 'soil sifta' can process soil dug directly
from the garden, separating the stones and vegetable matter as quickly as a man can
feed the device with material.
[0005] The present invention comprises a fabricated mesh drum, a frame holding the drum
at an inclined angle, an electric / petrol motor or hand crank, with a means of releasing
sifted-out material and a mechanism to deliver sifted soil and debris separately to
a barrow or other container.
[0006] The inclined drum with open end uppermost is loaded with garden material to be sifted.
The bottom end of the drum is closed except for a labyrinth formed by way of a helical
(thread like) surface whose ends overlap by a quarter turn. The gap is a result of
the pitch of the helix (150-300mm).
On rotating the drum in one direction the soil / material is agitated and separated,
allowing fine, broken soil to fall through the mesh walls of the drum, while the larger
debris is retained.
[0007] By reversing the direction of rotation of the drum the helical back plate actively
draws the debris out of the bottom end of the tube, delivering it directly into a
barrow or similar container.
[0008] A specific embodiment of the invention will now be described by way of example with
reference to the accompanying drawing:
[0009] Referring to the drawings 'fig 1, 2, 3' the 'soil sifta' comprises:
A. Rotating mesh drum. |
B. Helical Back plate. |
C. Motor or Crank Handle. |
D. Frame. |
E. Wheels. |
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[0010] Figure 4 illustrates the helical back plate B and how its contra-rotation expels
the unwanted retained debris.
1. A soil sifter comprising a rotating mesh drum wherein the bottom end of the inclined
drum is closed except for an exit labyrinth formed by way of a helical (thread like)
surface the ends of which overlap by more than 45°.
2. A soil sifter as in Claim 1, wherein the labyrinth is created by the pitch of the
helix.
3. A soil sifter as in Claim 1, wherein the rotation of the drum in one direction agitates
and separates allowing sifted soil to fall through the mesh walls of the drum. Reversal
of the direction of rotation of the drum expels the debris from the lower end of the
tube into a barrow or similar container.
4. A soil sifter as in Claim 1, comprising a rotating mesh drum supported on a frame
at an inclined angle and driven round by an electric/petrol motor or hand cranked
at either end.
5. A soil sifter as in Claim 1, wherein the upper end of the cylindrical mesh drum is
open for insertion of soil and debris mixtures.
6. A soil sifter as in Claim 1, wherein the inside of the tube is fitted with blades
to assist in the breaking up of clods of earth.
7. A soil sifter as in Claim 1, wherein the tube axis is angled to assist the soil to
move down the tube.
8. A soil sifter as in Claim 1, where the speed of rotation is from 10 rpm to 100 rpm.
9. A soil sifter as in Claim 1, wherein the mesh size can be adjusted.