GB2088187A

GB2088187A - Root crop harvester

Info

Publication number: GB2088187A
Application number: GB8131686A
Authority: GB
Original assignee: Hestair Farm Equipment Ltd
Current assignee: Hestair Farm Equipment Ltd
Priority date: 1980-11-27
Filing date: 1981-10-21
Publication date: 1982-06-09

Abstract

Depth control system for a potato harvester 10 comprises a hydraulic ram 46 to raise and lower a root lifting share 22 at the forward end of a digger web 24. Ram 46 is controlled by a solenoid valve to which depth- control signals are fed by a control switch 56 monitoring potato ridge height by means of a pneumatic sensor wheel 50 mounted on a leading arm 52 and riding along the top of the ridge. Sensor wheel 50 is positioned in front of share 22 by a distance corresponding to the response rate of the depth control system, having regard to the forward speed of the harvester. The system also includes an independently operable means to cause the hydraulic ram to raise the root lifting means. This means suitably comprises a double pole inhibit switch to isolate switch 56, and a manually operable height control means. <IMAGE>

Description

SPECIFICATION Root crop harvesters This invention relates to root crop harvesters and in particular, though not exclusively, to root crop harvesters in the form of potato harvesters.

An important feature of root crop harvester design is the provision of means to control the depth at which the root lifting means operates to raise the roots from the soil for passage into the harvester to undergo such processes as separation from soil, stones or crop material.

Many potato harvesters are provided with means whereby the root lifting means is merely set, manually, at a suitable position relative to the implement frame so as to lift the roots from the soil at the required depth. Other harvesters have been provided with a simple system for controlling the depth of operation of the root lifting means by means of a diabolo roller mounted on the root lifting means and which rides over the top of the potato ridge, following the contours thereof, and causing the root lifting means such as a share to rise and fall with it.

A further proposal in relation to control of the depth of operation of root lifting means has involved the use of a sensor following the ground contours, a hydraulic ram to raise and lower the root lifting means, and a hystraulic control system mechanically operated by the ground sensor.

None of the above-mentioned depth control systems have proved entirely satisfactory. The manually controlled system simply does not provide for depth control on-the-go whereby the harvester can be caused to respond to changing harvesting conditions.

The diabolo roller height control system apparently operates satisfactorily in the light soil conditions found in much of continental Europe but is unsatisfactory in heavy soil conditions where a high proportion of clods are encountered.

The last-mentioned servo type depth control system, being essentially mechanical, and operating through linkages is subject to the problem that there is inevitably a large amount of backlash and lost motion in the system which causes it to be unresponsive in operation and inaccurate. Moreover, in order to provide this system with feedback so that the lifting ram is deenergized when the required depth has been achieved, it has been necessary to provide a feedback linkage in addition to the framework of the implement -- which is an expensive and cumbersome addition to the harvester.

An object of the present invention is to provide a root crop harvester having improved depth control means for the root lifting means of the harvester.

According to the present invention there is provided a root crop harvester comprising: a frame; root lifting means mounted on the frame so as to be height-adjustable relative to the frame so as to vary the operating depth of the root lifting means; a hydraulic ram acting between the frame and the root lifting means so as to adjust the depth of operation of the latter; and control means for the hydraulic ram comprising a ground sensor, electrical switch means associated with the ground sensor, a solenoid valve connected to the electrical switch means and to the hydraulic ram so as to control the supply of hydraulic fluid from a source thereof to the ram in accordance with signals from the ground sensor, and independently selectively operable means to cause the hydraulic ram to raise the root lifting means relative to the frame.

The frame may be mounted on ground wheels and provided with a drawbar for attachment to a tractor. The invention is also applicable to selfpropelled harvesters.

The root lifting means may be in the form of a lifting share mounted at the forward end of a primary digger web. Other types of root lifting means are equally usabie in association with the invention, such as rotary disc type shares. The root lifting means may be mounted on a sub frame which is pivotally connected to the main frame of the harvester so that the root lifting means moves up and down.

The hydraulic ram acting between the frame and the root lifting means may be mounted on the main frame of the harvester and connected to a sub frame which is movable up and down with the root lifting means.

The ground sensor is preferably in the form of a wheel provided with a pneumatic tyre and positioned ahead of the root lifting means for contact with the centre of a potato ridge. The wheel may be mounted on a leading arm which is pivotally connected to the frame of the harvester so as to float up and down entirely independently of the root lifting means. A chain or the like may be provided to iimit downward movement of the sensor wheel during transport. Alternative sensors include diabolo wheels and the like, and sensor wheels mounted for contact with the ground at one or both sides of a potato ridge being harvested.

The electrical switch means associated with the ground sensor preferably comprises proximity switches, such as micro switches. Alternatively, a similar photo-electrical equivalent system could be provided. The electrical switch means is preferably mounted on structure associated with the root lifting means so as to be raised and lowered therewith. Position adjustment means may be provided for manually moving the electrical switch means relative to said structure so as to change the depth at which the height control system is set to operate.

The independently selectively operable means to cause the hydraulic ram to raise the root lifting means relative to the frame may comprise an inhibit system for disconnecting said electrical switch means from the solenoid valve and for providing manual control of the solenoid valve to raise and lower the root lifting means. Such provision is needed at the end of each row of crop to be harvested. Manual control of the solenoid valve may be provided by means of a manually operable switch provided in the cab of a tractor hauling the harvester or provided at the control platform of the harvesteriself. Such a manually operable switch is preferably spring-returned to a centre position in which no signal is transmitted.

An alternative means of causing the ram to raise the root lifting means relative to the frame could be in the form of any suitable expedient for actuating the micro switch (or its equivalent) which generates a lift signal.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows, diagrammatically, a side elevation view of a potato harvester; Figure 2 shows, diagrammatically, and on a larger scale a portion of control means for the root lifting means of the harvester of Figure 1-, and; Figure 3 shows a circuit diagram relating to the control means of Figure 2.

As shown in Figure 1 a root crop harvester in the form of a potato havester 10 comprises a frame 12 mounted on rear ground wheels 14 and having a draw bar bar 16 at its forward end for attachment to an agricultural tractor (not shown).

A drive input connection 1 8 is provided for connection by means of a shaft 20 to the power take off drive of the tractor.

Harvester 10 comprises a root lifting share 22, a primary digger web 24, a haulm elevator 26, a main elevator 28 and a series of separating conveyors 30 and 32 whereby potatoes are separated from clods, earth and other matter prior to being deposited in a tank 34.

The present invention, relating to a depth control system for share 22, is in no direct way related to the details of the structure and arrangement of those parts of the harvester to which the crop and soil is carried after it leaves the primary digger web 24, and thus these parts of the harvester are shown merely by way of example.

The height of frame 12 relative to the ground 36 is determined, during use, by the height of the forward end of draw bar 1 6 relative to the ground -this height being determined by the tractor drawing the harvester.

Lifting share 22 is mounted at the forward and lower end of digger web 24 so as to penetrate the potato ridge 37 and lift the ridge and the crop contained therein onto the web 24. A pair of rotatable discs (not shown) are provided one at each side of the share to guide the ridge onto the web.

Primary digger web 24 is mounted on its own rigid subframe 38 comprising side frame members 40, one at each side of the web and an extension sub-frame 42, rigid therewith and extending forwardly for a purpose to be described. Subframe 38 is pivotally mounted on main frame 12 about a horizontal laterally extending pivot axis 44 so that the root lifting share 22 is height adjustable relative to the main frame to vary its operating depth.

A hydraulic ram 46 is mounted at the forward end of main frame 12 and is pivotally connected at 48 to extension subframe 42 so as effectively to act between the main frame 12 and the sub frame 38 to adjust the height of share 22. Ram 46 is double acting and is connected to a source of hydraulic pressure (not shown) and to control means (to be described below) therefore. The source of hydraulic pressure comprises a pump (not shown) driven by shaft 20 and mounted on frame 12. Alternatively, the tractor hydraulic system could equally well operate the ram 46 directly.

A ground sensor in the form of a wheel 50 having a pneumatic tyre is mounted at the forward end of a leading arm 52 which is mounted by a pivot connection 54 on sub-frame 38 so as to be movable up and down relative thereto. Wheel 50 is positioned centrally of share 22 so as to contact the middle of the top of a potato ridge 37 being harvested.

Electrical switch means 56 is associated with ground sensor wheel 50 so as to be actuated by the sensor and to produce signals for a solenoid valve 58 (see Figure 3) controlling hydraulic ram 46. Switch means 56 is controlled by a switch rod 60 having a roller 62 at its lower end for rolling contact with leading arm 52. Switch rod 60 carries a switch element 64 to actuate a pair of micro switches 66 and 68 in accordance with up and down movement of arm 52 following wheel 50 (see Fig. 2).

Electrical switch means 56 is mounted in a switch box 70 carried on sub-frame 38 and which is height adjustable relative thereto between guides 72 and 74 by means of a hand wheel 76 and a screw threaded rod adjuster 78 connected to the switch box. An index 80 mounted on the side of switch box 70 co-operates with a scale 82 whereby the depth of operation of share 22 is preset before work commences.

Figure 3 shows the circuit diagram. A source 84 of 12 volts direct current is connected to solenoid valve assembly 58 which comprises individual solenoid valves 86 and 88 to control hydraulic fluid flow to and from double acting ram 46. Electrical switch means 56 is connected between 12 volt source 84 and the solenoid valve assembly so as to control the assembly in accordance with signals generated by up and down movement of wheel 50.

In addition to the above, independently selectively operable means is provided to cause ram 46 to raise sub-frame 38 and root lifting share 22 relative to main frame 12. Such means comprises a double pole inhibit switch 92 and a manually operable height control switch 94.

Inhibit switch 92 is operable to isolate electrical switch means 56 from solenoid valve assembly 58 so that the solenoid valve assembly is then actuable solely by height control switch 94.

In use, wheel 50 rides along the top of the potato ridge 37 moving up and down about pivot 54 to follow the ridge contours. Such movement of the wheel causes vertical movement of switch rod 60 whereby switch element 64 actuates micro switches 66 and 68 causing signals to be sent to solenoid valves 86 and 88 whereby ram 46 is appropriately extended or retracted until subframe 38 (and hence lifting share 22) is brought to a position at which switch element 64 is centred between the micro-switches 66 and 68 and no signal therefrom is generated. This position is dependent upon the position of switch box 70 relative to sub-frame 38-which is itself determined by the setting of hand wheel 76. The system operates to maintain share 22 at the depth corresponding to the set position of switch box 70 determined by hand wheel 76 (and indicated by the position of index 80 on scale 82).

If share 22 tends to work deeper, sub-frame 38 moves downwards, moving switch box 70 and micro switches 66 and 68 with it whereby one of the micro switches is actuated and a lift signal is generated and ram 46 is caused to retract.

At the end of each row being harvested the independently and selectively operable means (comprising inhibit switch 92 and height control switch 94) is actuated so as to cease automatic depth control and change to manual height control. On operating inhibit switch to isolate electrical switch means 56, the driver of the tractor then operates height control switch 94 to cause solenoid valve assembly 58 to cause ram 46 to retract and to raise share 22 to its transport position. The tractor and harvester turn round and when it is desired to re-commence harvesting inhibit switch 92 is closed and the automatic control system takes over.

The embodiment of the invention described above has the advantage of considerable sensitivity to small height control signal, little mechanical backlash and rapid response. A time delay is built into the system to allow for the distance in the fore/aft direction between wheel 50 and share 22 having regard to the speed of forward travel of the harvester.

In a further embodiment of the invention, which is not illustrated in the accompanying drawings, the roller 62 which is mounted at the lower end of switch rod 60 for rolling contact with leading arm 52, is replaced by a pivotal connection between rod 60 and arm 52, whereby bouncing of the rod 60 relative to sensor wheel 50 is avoided and response of the depth control system to rapidly changing height control signals is improved.

Claims

1. A root crop harvester comprising: a frame; root lifting means mounted on the frame so as to be height-adjustable relative to the frame so as to vary the operating depth of the root lifting means; a hydraulic ram acting between the frame and the root lifting means so as to adjust the depth of operation of the latter; and control means for the hydraulic ram comprising a ground sensor, electrical switch means associated with the ground sensor, a solenoid valve connected to the electrical switch means and to the hydraulic ram so as to control the supply of hydraulic fluid from a source thereof to the ram in accordance with signals from the ground sensor, and independently selectively operable means to cause the hydraulic ram to raise the root lifting means relative to the frame.

2. A harvester according to claim wherein said frame is mounted on ground wheels and provided with a drawbar for attachment to a tractor.

3. A harvester according to claim 1 in the form of a self-propelled harvester.

4. A harvester according to any one of the preceding claims wherein said root lifting means is in the form of a lifting share mounted at the forward end of a primary digger web.

5. A harvester according to any one of the preceding claims wherein said root lifting means is mounted on a sub-frame, the sub-frame being pivotally connected to the main frame of the harvester to permit up and down movement of said root lifting means.

6. A harvester according to claim 5 wherein said hydraulic ram acts between said sub-frame and the main frame of the harvester.

7. A havester according to any one of the preceding claims wherein said ground sensor is in the form of a wheel.

8. A harvester according to claim 7 wherein said wheel is provided with a pneumatic tyre.

9. A harvester according to claim 7 or 8 wherein said wheel is positioned ahead of the root lifting means for contact with the centre of a potato ridge.

10. A harvester according to any one of claims 7, 8 or 9 wherein said wheel is mounted on a leading arm, having regard to the direction of normal forward operative movement of the harvester, the leading arm being pivotally connected to the main frame of the harvester so as to float up and down independently of said root lifting means.

11. A harvester according to any one of the preceding claims wherein said electrical switch means associated with said ground sensor comprises proximity switches or a photo-electrical position sensor.

12. A harvester according to claim 11 wherein said electrical switch means is mounted on structure associated with said root lifting means so as to be raised and lowered with the root lifting means.

13. A harvester according to claim 12 wherein position adjustment means is provided to permit manual adjustment of the electrical switch means relative to said structure so as to change the depth at which the depth control system is set to operate.

14. A harvester according to any one of the preceding claims wherein said independently selectively operable means to cause the hydraulic ram to raise the root lifting means relative to the frame comprises an inhibit system for disconnecting said electrical switch means from said solenoid valve and for providing manual control of the solenoid valve to raise and lower said root lifting means.

1 5. A harvester according to claim 14 wherein said manual control of the solenoid valve is provided by means of a manually operable switch adapted to be mounted in the cab of a tractor hauling the harvester or provided on the control platform of the harvester itself.

1 6. A harvester according to claim 1 5 wherein said manually operable switch is spring-returned to a centre position in which no signal is transmitted.

1 7. A harvester according to claim 1 substantially as described herein with reference to the accompanying drawings.

18. A root crop harvester substantially as described herein with reference to the accompanying drawings.

1 9. A method of harvesting root crops comprising providing a harvester having a frame and root lifting means mounted on the frame so as to be height-adjustable relative to the frame and a hydraulic ram acting between the frame and the root lifting means, and causing said root lifting means to lift roots from the ground while controlling the operating depth of the root lifting means by means of a ground sensor, electrical switch means associated with the ground sensor, and a solenoid valve connected to the electrical switch means and to the hydraulic ram.

20. A method according to claim 19 wherein the root lifting means is raised relative to the frame by means of independently selectively operable means to energize said hydraulic ram.

21. A method of harvesting root crops substantially as described herein with reference to the accompanying drawings.