GB2318135A

GB2318135A - Soil auger and mechanical soil sampler

Info

Publication number: GB2318135A
Application number: GB9621208A
Authority: GB
Inventors: Terence Mcburney; Roger Charles Balls
Original assignee: Minister of Agriculture Fisheries and Food UK
Current assignee: Minister of Agriculture Fisheries and Food UK
Priority date: 1996-10-11
Filing date: 1996-10-11
Publication date: 1998-04-15
Also published as: GB9907411D0; GB9621208D0; AU4630897A; GB2333547B; WO1998016714A1; GB2333547A

Abstract

A mechanical soil sampler including a support frame including guide means 13, 13', baseplate 15 and rotary drive means 9, where said support frame is adapted to retain an auger 2 in movable mounting to guide the auger 2 during insertion into and removal from the ground. The auger 2 comprises a fluted drill bit adapted at one end for operably coupling to the rotary drive means 9. A scraper 4 is mounted on the auger and adapted for engagement with the flute of the auger to dislodge soil samples therefrom during the relative movement of the scraper and the auger. A bucket 16 may also be provided to collect the dislodged soil samples.

Description

Soil Anger and Mechanical Soil Sampler The present invention relates to a soil auger and in particular to a screw type auger and to a mechanical soil sampler employing this auger.

There currently exists the need for a soil sampler which can be used to rapidly obtain a large number of soil samples, for example in order to monitor the levels of agro-chemicals present in the ground of a field. This need is particularly acute for arable farmers. These farmers need to monitor nitrogen levels, an essential plant nutrient, in a field down to the depth of root penetration (typically about 1 metre) in order to optimise the use of nitrogen fertiliser on the crop. Exceeding the crops' requirement wastes money, depresses yield and may also lead to nitrate accumulation in watercourses, subterranean aquifiers and even in the edible product itself.

Hand augers are well known but are slow to operate, typically permitting the sampling of only 66 fields per day and are prone to causing strain injuries in the operators. One known mechanical screw-type soil auger is described in US 3 356 168 and comprises a shaft having a point at one end with the opposite end being adapted to fit a standard drill chuck. A continuous flighting is spot welted onto the shaft and extends along its length. The purpose of this flighting is to scatter soil around the edge of a hole it produces and therefore cannot be employed to provide a useflil soil sample.

An auger which is specifically designed to produce a soil sample from which depth information may be obtained is disclosed in US 4 779 689. This auger comprises a hollow cylindrically body which is provided with cutting teeth about the perimeter of one end and a shaft at the other end which is adapted for attachment to an electric hand drill. The auger produces a plug of soil which is held within its cylindrical body and which is removed by pushing the sample through a slot provided along the length of the body. This has the disadvantages that the soil sample taken is of a relatively large diameter, which måy necessitate the taking of further sub-samples, and that the soil sample itself may be broken because of the particular way in which it has to be extracted from the auger. This leads to an increased probability of cross contamination of soil from different depths and an increased difficulty in correlating the soil from the sample with the depth in the ground from which it was taken.

According to a first aspect of the present invention there is provided a soil auger comprising a fluted drill bit provided with one end adapted for operably coupling to a rotary drive means and a scraper adapted for engagement with the flute to dislodge soil samples therefrom during their relative movement.

Usefully the scraper comprises a collar rotatably mounted about the drill bit and having a surface adapted to engage the flute thereof. With this arrangement the screw action of the relative rotation of the bit and the collar effects displacement of the drill bit through the collar.

This has the advantage that the collar, being mounted on the drill bit, needs no additional supporting structure and so provides a simplified design of the soil auger. A further advantage of this arrangement is that the soil sample may be dislodged from the flute in an easily controlled manner simply by controlling the relative rotation of the collar and bit. This rotation may be achieved either manually or mechanically, for example by using the same rotary drive means as is employed to drive the bit into the ground.

According to a second aspect of the present invention there is provided a mechanical soil sampler comprising a soil auger according to the first aspect and a rotary drive means operably coupled thereto.

The rotary drive means may, for example, be a commercially available electric hand drill. This provides a mechanical soil sampler which is relatively lightweight and inexpensive to construct.

Preferably the mechanical soil sampler additionally comprises a support frame having guide means, for example a cooperating guide bar and carriage arrangement, which is adapted to retain the rotary drive means and soil auger in moveable mounting to guide the drill bit during insertion into and extraction from the soil and to support the drill bit substantially perpendicular to the soil during sample collection. This arrangement facilitates the accurate correlation of soil sample depth with position of sample on the drill bit.

Collection means, cooperable with the mechanical soil sampler, may also be provided which is adapted to collect discrete soil samples dislodged by the scraper from separate predetermined regions of the drill bit.

This collection means may for example comprise a plurality of sample holders having an open end for receiving dislodged soil in attachment to the support frame so as to lie parallel with and extend along substantially all of the fluted region of the drill bit. For ease of construction these sample holders may comprise a single trough being provided with a plurality of internal partitions to segregate soil samples collected from different regions of the drill bit corresponding to the regions between the partitions. Alternatively, the collection means may be a bucket locatable adjacent the scraper. In embodiments where the soil is dislodged from the flute of the drill bit by rotating the collar then the bucket may be slideably mounted on the guide means and operably connected to the collar, for example by latching it to the collar, so as to maintain the relative spatial relationship between the collar and the bucket as the collar moves along the bit. In use the bucket will be periodically emptied to provide discrete soil samples from the predetermined regions. These regions could for example represent 0-30cm, 30-60cm and 60-90cm soil sample depths.

Furthermore, the inventors have discovered that under certain circumstances, particularly when used in unconsolidated soils, sample loss may occur from the flutes of the drill bit of the present invention and that such loss may be reduced by controlling either or both of the rotational speed of the bit and the rate of its penetration into the soil. In order to reproducibly control the rate of penetration of the drill bit into the soil the mechanical soil sampler may additionally comprise a latch means for latching the collar to the support frame, for example to the base of the frame. This arrangement is such that displacement of the bit into the ground is controlled by its rotational speed, that is, by the screw action between the drill bit and the flute engaging surface of the collar.

Further control of the rotation of the drill bit may be achieved by providing a decoupling device having a first part coupled to the drive means, a second part coupled to the drill bit and a biasing means adapted to hold apart the first and second parts to decouple the one from the other. The operator then controls the rotation of the drill bit through the application of an external force to bring the first and second parts into operational contact. Usefully the decoupling device may be adapted to couple the rotation of the drive means to the drill bit irrespective of the direction of the externally applied force along the axis of the drill bit.

Embodiments of the invention will be now be described, by way of example only, with reference to the drawings of the accompanying figures, of which: Figure 1 shows a part section of a soil auger according to the first aspect of the present invention.

Figure 2 shows a mechanical soil sampler according to the second aspect of the present invention.

Figure 3 shows a part section view of a decoupling device usable with the mechanical soil sampler of figure 2 Referring now to Figure 1 a soil auger 1 comprises a lOmm shank diameter drill bit 2 having a flute 3 extending for approximately 1 meter along the shank. A scraper, comprising a collar body 4 and an insert 5 having an edge 6 adapted to engage the flutes 3. This arrangement is such that the relative rotation of the drill bit 3 and the scraper 4,5 causes the edge 6 to move screw like along the flutes 3 to dislodge any soil retained therein. The scraper 4,5 is also provided with a pair of latch bars 7, 7' (not shown) each of which is, towards one end, pivotally mounted on the body 4.

One end of the auger 1 is mounted in the chuck 8 (Figure 2) of an electric drill 9 which is connected to the rotatable shank of the electric drill 9 through a decoupler 10 and a 1:200 speed reduction gear 11. This gear 11 permits the motor of the drill 9 to run at near full power, to provide maximum torque, whilst permitting the drill bit 2 to rotate slowly to avoid possible loss of the soil sample. The body of the drill 9 is adapted for slidable mounting on guide bars 13, 13' of the support frame 14. The support frame 14 also comprises a base plate 15 through which the drill bit 2 may pass and which has recesses or holes into which the free ends of the latch bars 7, 7' can be located (shown as dashed construction). When latched in this position, the collar body 4 is prevented from rotating with the drill bit 2 which then has to pass screw like through it. This results in the rotational speed of the bit 2 controlling its rate of insertion into the ground. A collection bucket 16 having recesses 17, 17' for receiving the latch bars 7, 7' is slidably mounted onto the guide bars 13, 13' and in use may is latchable to the collar body 4 in order to collect soil samples dislodged from the flute 3 of the bit 2 as the collar body 4 passes along the bit 2. In use the bit 2 and collar body 4 are rotated relative to one another so as to permit passage of the collar body along the drill bit 2. The bucket 16 collects soil dislodged from the flute 3 by the edge 6 and is removed and emptied periodically so that individual soil samples, corresponding to predetermined regions through the ground, may be collected and tested.

It will be clear to a person skilled in the art that the collection of individual soil samples may be achieved using a collar and bucket which remain stationary whilst the drill bit is rotated.

Wheels (not shown) are also provided on the support frame so that the whole soil sampler may be easily transported about the sample site.

The two-way decoupler 10 is shown in Figure 3 and comprises a housing 18 having an internal cavity 19 adapted to receive the shaft 20 of the drill 9. A collar 21 is slidably located in the cavity 19 and is in connection with the shaft 20 to rotate as the shaft 20 rotates. The collar 21 is provided with holes 22,22' which are adapted to receive and locate one pair of corresponding opposing pairs of lugs 23, 23' and 24,24'. A pair of spring coils 25,25' act to bias the collar out of contact with both pairs of lugs in the absence of an externally applied force. When an operator either pushes or pulls the drill 9 movement of the rotating shaft 20 urges the collar 21 against one of the springs 25,25' and locates one of the pair of lugs 23,23' (or 24,24' depending on the direction of the extemally applied force). Once the lugs 23,23' are located in the holes 22,22' the whole body 10 rotates with the shaft 20.

Claims

1. A soil auger comprising a fluted drill bit provided with one end adapted for operably coupling to a rotary drive means and a scraper adapted for engagement with the flute to dislodge soil samples therefrom during their relative movement.

2. A soil auger as claimed in Claim 1 characterised in that the scraper comprises a collar rotatably mounted about the drill bit and having a surface adapted to engage the flute thereof.

3. A soil auger as claimed in Claim 2 characterised in that the collar comprises a body portion and an insert, the insert being provided with the surface outward of the body portion and away from the end of the bit adapted for coupling to the rotary drive means.

4. A mechanical soil sampler comprising a soil auger as claimed in any one of the preceding claims and a rotary drive means operably coupled thereto.

5. A mechanical soil sampler as claimed in Claim 4 characterised in that it additionally comprises a support frame, the support frame being provided with guide means adapted to retain the drive means and the auger in moveable mounting to guide the drill bit during insertion into and extraction from the soil and in use being capable of supporting the drill bit substantially perpendicular to the ground.

6. A mechanical soil sampler as claimed in Claim 4 characterised in that the auger is that claimed in either Claim 2 or Claim 3 and in that there is additionally provided latch means for latching the collar to the support frame.

7. A mechanical soil sampler as claimed in Claim 6 characterised in that the latch means comprises latch bars having a first end pivotally connected to the collar and a second end engagable with corresponding recesses provided in the support frame to latch the collar.

8. A mechanical soil sampler as claimed in Claim 7 characterised in that the support frame additionally comprises a base plate for contacting the ground, the recesses being provided in the base plate.

9. A mechanical soil sampler as claimed in any of the Claims 6 to 8 characterised in that there is additionally provided collection means adapted to collect discrete soil samples from predetermined regions ofthe drill bit.

10. A mechanical soil sampler as claimed in Claim 9 characterised in that the collection means comprises a removable bucket locatable adjacent the collar.

11. A mechanical soil sampler as claimed in Claim 10 characterised in that the bucket is operably connected to the collar to maintain their relative spatial relationship as the collar moves along the drill bit.

12. A mechanical soil sampler as claimed in any one of the Claims 4 to 11 characterised in that there is further provided a decoupling device having a first part coupled to the drive means, a second part coupled to the drill bit and a biasing means adapted to hold apart the first and second parts to decouple the one from the other.

13. A mechanical soil sampler as claimed in Claim 12 characterised in that the decoupling device comprises a housing having an internal cavity adapted to receive a shaft of the drive means and having located slidably therein a collar cooperable with the shaft to rotate therewith, the collar being provided with holes adapted to receive and locate one pair of corresponding opposing pairs of lugs of the cavity walls and being biased out of contact with the lugs.