GB2099484A - Machine for digging peat - Google Patents

Abstract

A machine for digging moor peat comprises a frame (10), carrying power transmission equipment (13) to operate both an excavator disc (14), and a press (18) filled by the action of the disc (14). The press (18) includes a transfer screw rotary within a nozzle box (21) provided with nozzle openings for compressed product. In order to minimise blockage by woody material of these outlet nozzles the box (21) of the press is provided with a return pipe (20) for the peat mass, by-passing the zone of the nozzle openings, whereby a recirculation of a promotion of the peat mass is obtained, to promote a grinding action and thereby reduce the tendency to nozzle blockages. <IMAGE>

Description

SPECIFICATION Machine for digging peat The subject of the present invention is a machine, more especially a small-scale machine, for digging and handling moor peat, and more particularly in the form of non-predried peat.

Finnish Patent No. 53,392 describes a machine for digging moor peat, comprising a frame, an excavator disc, a transmission system, and a press. This prior art machine cuts, grinds and mixes the peat and presses it into compact pieces of specified shape. Its press is placed in front of and above the excavator disc, as viewed in the driving direction of the machine. The peat flies by the effect of centrifugal force directly off the excavator disc into the press without any significant change in direction.

In the press of such a machine, a transfer screw rotates inside a cylindrical housing, possibly conical at its outer end. At or towards this outer end are provided several nozzle openings and pipes, out of which the compressed and ground peat is discharged while being at the same time broken into pieces.

Woody solids, such as parts of logs or roots of trees are frequently present in the peat and arrive in the press. These solids cause frequent blockages of the nozzle openings in the prior art machines, and interrupt their operation. The cleaning of such blockages is time-consuming and laborious.

It is an object of the present invention to avoid the disadvantages described above and to provide such a machine, more especially a small-scale machine for digging peat. An additional object of the invention is to improve the prior art machine of the type described above so that the peat mass becomes even more compact, homogeneous and void of air, and dries quickly.

A further object of the invention is to provide peat pieces of smooth unbroken surface.

The invention consists in a machine for digging moor peat, of the type in which a mobile frame carries a power transmission, driving both (a) a peat-excavating means and (b) a press comprising an elongate housing and means for transferring along the housing and extruding from a plurality of nozzle outlets in the housing peat fed to the press from the excavating means; in which machine is provided at least one additional return duct or pipe, communicating with the interior of the housing to either side of the nozzles, to achieve recirculation of a proportion of the peat transferred along the housing and thereby reduce in size material tending to block the nozzle outlets.

When a duct or pipe is used as defined above solid but breakable material in the peat mass, such as pieces of wood etc., can be recirculated a sufficient number of times as to be crushed to such extent that they are able to pass through the nozzle openings without blocking them.

The recirculation of the peat mass also promotes the compactness of the mass and the elimination of air. Also, it equalises the pressure at all the nozzle openings so that the peat mass is discharged evenly.

In a preferred embodiment of the invention the nozzle outlets further comprise pipes of appropriate length having a smooth and low friction interior surface e.g. of synthetic polymer.

This produces pieces of peat with a more dense structure and smooth face.

The invention will be further described with reference to embodiments illustrated in the attached drawing, in which: Figure 1 is a side view of a small peat digging machine in accordance with the invention, Figure 2 is a top view of the machine of Figure 1, Figure 3 is a front view of the machine of Figure 1, Figure 4 is a diagrammatic section through a cylindrical box and associated nozzle pipes, and Figure 5 is an axial view of a conical nozzle box with a by-passing pipe.

The machine shown in Figures 1,2 and 3 has a frame 10 for connection by means of connecting means 11 to (for example) the 3-point lifting gear of a tractor. The tractor (not shown) pulls the machine and provides power by means of cardan shaft 1 2 to a cog-wheel and chain transmission, whose casing is denoted with reference numeral 1 3. This transmission turns an excavator of known type, the screw 1 9 of the press 1 8 and the peatfield levelling screw 1 5. A drum 1 6 is connected to the rear part of the machine by means of pivotal arms 25, to compact and level the peat-field and to support the rear of the machine adjustably, so that the working depth of the machine can be adjusted by means of a hydraulic cylinder 1 7 fitted between the arms 25 and the frame 10.

The relative arrangement of the excavator disc 14 and of the press 1 8 is preferably similar to that shown in the Finnish Patent No. 56,392. When the machine travels forwards, blades (not shown) of the excavator disc 1 4 detach and grind the peat and throw it further into the press 18. Transfer screw 1 9 within this press progresses through the nozzles 23 onto the field that has already been levelled and compacted by the drum 1 6.

The press has now been provided with a return pipe 20 or 20', which by-passes the zone of the nozzle openings 23.

As is shown in Figures 1, 2, 3 and 4, the return pipe 20 extends from the downstream end of the cylindrical housing or nozzle box 21 towards the feeding end of the peat mass.

In the embodiment of Figure 5, the housing or nozzle box 21' of the press is gently conical, and a correspondingly conical feeder screw 19' operates inside a box, as illustrated by broken lines. The return pipe 20' begins smoothly at the downstream end of the box 21' and passes in a curved path to the upstream end.

The length of the return pipe 20, 20' is for example, about 1 metre, and the return pipe becomes wider in the direction of the return flow Fa, preferably so that the ratio of the crosssectional area A2 (of the discharge end of the return pipe 20, 20') to the area A, (of the initial end) i.e. A2/A1 is approximately from 2 to 6 and preferably about 4. The return pipe 20, 20' has a smooth internal surface. It should preferably not extend too far to the upstream side ahead of the zone of the nozzle openings 23, because that causes an unnecessary loss of power.

In practice it has been found favourable to dimension the ratio of the cross-sectional area Ao (of the inlet end of the nozzle box 21) to the area A1 (of the inlet end of the return pipe 20, ') so that Ao/A1 is approximately 5 to 7 and preferably about 6.

The return pipe in accordance with the invention functions as a balancing pipe, through which the return flow F1 takes place so that solid particles do not accumulate in the nozzle box 21, 12' of the press and block the openings 23. By using this return pipe 20, 20' continuous recirculation is obtained. The pressure P1 at the end of the screw 19, 19' and the pressure P2 at the discharge end of the return pipe are either substantially equal or pressure P1 is only slightly higher than the pressure P2. Under these circumstances the pressure can be made substantially uniform within the entire axial length of the nozzle box 21,21' over the zone of the nozzle openings 23.

In front of the excavator disc 14, is provided a ski-shaped wall 28 fixed to the frame 10 of the machine by means of pivoting link rods. Wall 28 prevents throwing of peat and of solid particles included therein towards the tractor.

The nozzle box 21, 21' of the press together with the return pipe 20, 20' and the nozzle pipes 26 are arranged as an integrated unit and are replaceable as one unit. For this purpose, the said box, with the components included in it is attached to the pipe of the press 1 8 by means of a flanged joint 27 or by any like detachable connection of snap joint.

According to Figure 4, short stub pipes 24 have been fastened by welding to the box 21 of the press. Extensions of the said stub pipes are constituted by nozzle pipes 26, which are preferably flexible plastic pipes. When plastic pipes of smooth internal surface and of low coefficient of friction are used as these nozzles pipes 26, good shaping of the peat pieces is obtained, i.e., the peat pieces have a dense and smooth face and hold together well.

By means of adjustment of the conical shape of the noule box 21, it is also possible to affect the degree of working of the peat mass. Thus, by such adjustment and by adjusting (a) the length and the cross-sectional areas A, and A2 of the return pipe 20 (b) the ratio of the said areas A1 and A2, and (c) the position of the outlet end and inlet end of the return pipe 20, it is possible to optimize the operation of the nozzle box for different peat qualities and, at the same time, to minimize the tendency of blocking of the nozzle box as well as to produce a compacted, sufficiently homogeneous and air-free peat, especially smallsize peat. (In this connection, by small-size peat is meant a peat product whose diameter is less than 50 mm.) The operation of the nozzle box 21 of the press can also be affected by varying the length L of the nozzle pipes 26, particularly in dependence upon the dryness of the peat. Since the plastic nozzle pipes 26 can be attached to the stub pipes 24 by means of snap joints, the nozzle pipes 26 may, if necessary, be exchanged so as to be of different lengths and if required of different cross-sectional areas.

An important factor in the operation of the return pipe 20, 20' by-passing the zone of the nozzle openings 23 is that by its recirculation effect pieces of wood and like material can circulate a sufficient number of times so as to be crushed into small enough pieces to be discharged through the nozzle openings 23. Thus, no blockage or only infrequent blockages can occur.

Claims (14)

1. A machine for digging moor peat, of the type in which a mobile frame carries a power transmission, driving both (a) a peat-excavating means and (b) a press comprising an elongate housing and means for transferring along the housing and extruding from a plurality of nozzle outlets in the housing, peat fed to the press from the excavating means; in which machine is provided at least one additional return duct or pipe, communicating with the interior of the housing to either side of the nozzles, to achieve recirculation of a proportion of the peat transferred along the housing and thereby reduce in size material tending to block the nozzle outlets.

2. A machine as claimed in claim 1 in which one end of the duct or pipe is located at or near the end of the elongate housing and the other end of the duct or pipe is located immediately upstream of the nozzle outlets in the housing.

3. A machine as claimed in claim 1 or 2 in which the cross-sectional area of the duct or pipe increases in the direction of return flow.

4. A machine as claimed in claim 1,2 or 3 in which the ratio of the cross-sectional area of the upstream or return end of the duct or pipe to that of the downstream or inlet end is from 2:1 to 6:1.

5. A machine as claimed in claim 4 in which the said ratio is substantially 4:1.

6. A machine as claimed in any one preceding claim in which the elongate housing is conical and one end of the duct or pipe is connected at the narrow end of the conical housing.

7. A machine as claimed in claim 6 in which the ratio between the cross-sectional area of the inlet end of the elongate conical housing to that of the downstream end or inlet end of the duct or pipe is from 5:1 to 7:1.

8 A machine as claimed in claim 7 in which the said ratio is substantially 6:1.

9. A machine as claimed in any one preceding claim in which the nozzle outlets further comprise pipes having a smooth low-friction interior surface, to smooth and densify the extruded peat pieces.

10. A machine as claimed in any one preceding claim in which the mobile frame further carries a transverse levelling screw driven by the transmission to level the excavated surface, and a trailing drum to compact the surface so levelled.

11. A machine as claimed in any one preceding claim in which the peat-excavating means is a rotary excavator disc, and in which the press is located to receive excavated peat flung off this disc by centrifugal force.

1 2. A machine as claimed in any one preceding claim further comprising a protective guard wall on the frame to shield a towing tractor from excavated peat.

13. A machine as claimed in any one preceding claim in which the elongate housing, the duct or pipe, and the nozzle outlets together constitute a separately detachable and replaceable sub-unit.

14. A machine for digging moor peat substantially as herein described with reference to, and as illustrated in, the accompanying drawings.