GB2141012A

GB2141012A - Crop harvester

Info

Publication number: GB2141012A
Application number: GB08314893A
Authority: GB
Inventors: Cedric Sharpe
Original assignee: Massey Ferguson Services NV
Current assignee: Massey Ferguson Services NV
Priority date: 1983-05-31
Filing date: 1983-05-31
Publication date: 1984-12-12
Also published as: GB8314893D0; EP0153321A1; WO1984004652A1; FI850391L; FI850391A0; GB2141012B; AU3016984A

Abstract

An automatic table height control system for maintaining the height of a crop cutting table (3) of a crop harvesting machine at a predetermined level above the ground comprising a control device (6) adapted to control an actuator (5) for raising and lowering the table, the control device including a movable control element (9) that assumes a neutral position or raise and lower positions either side of the neutral position in each of which it causes the actuator to raise or lower the table, respectively; a ground sensor (10) that senses the level of the ground and assumes a median position when the table is at a pre-determined set height above the ground and moves either side of the median position with changes in ground level; a linkage (16-22) permanently connecting the ground sensor (10) to the control element (9) so that when the ground sensor is in the median position the control element is in the neutral position, and movement of the sensor from the median position, caused by a rise in ground level, moves the control element to the raise position; and an automatic mode selection mechanism (30, 31) comprising a mode selection lever (30) that is movable between ON and OFF position and is connected via spring means (31) to said linkage (22) so that when in the ON position, the spring means (31) urges the linkage (22) in that sense to move the control element (9) to the lower position, and when in the OFF position, the spring means (31) does not act on the linkage (22). The linkage (16 to 22) includes a Bowden cable (19) comprising inner and outer coaxial cables (20, 23), the inner cable (20) being connected at one end to the ground sensor (11) and at the other end to a return lever (22) which is connected in turn to the control element (9). The outer cable (23) is connected at one end to a height of cut control lever (28) and at the other end to a spring-loaded pivot arm (24) that resists straightening of the outer cable.

Description

SPECIFICATION Combine harvester This invention relates to an automatic table height control system for maintaining the height of a crop cutting and gathering table of a harvesting machine at a predetermined level above the ground.

Automatictable height control systems are known such as shown in British parent specification number 1 124111 in which ground sensing fingers on the underside of a combine table are connected via a mechanical linkage including a Bowden cable to a hydraulic control valve controlling the table lift rams so that movement of the sensing fingers in response tovariationsintheground level controls operation of the lift rams and thereby maintains the table at a substantially constant predetermined height above the ground. The height of the table can be controlled manually by a control leverthat is connected to the control valve. Automatic table height control is engaged by a selection lever that serves to connectthe Bowden cable to the manual control lever so thatthe sensing fingers operate the latter.Thus, manual or automatictable heightcontrol is possible depending upon whether or notthe selection lever is coupledto the manual control lever. Also, manual control can be used to over-ride automatic control by incorporating an over-ride spring in the Bowden cable connection so thatthe manual control lever can be operated to raise the table without disengaging the selection lever.

Release ofthe manual control lever then allows automatic control to resume.

An object of the present invention is to provide an improved automatic table height control system, in particular, a simplersystem than the aforesaid system, and one which provides a modified mode of automatic control that allows the table to be set at said predetermined height as forfull automatic control but causes the table to be raised automatically and held at a higher level when rough ground conditions when these are sensed by the ground sensors.

This object is achieved by providing an automatic table height control system comprising a control device adapted to control an actuator for raising and lowering the table, the control device including a movable control element that assumes a neutral position or raise and lower positions either side of the neutral position in each ofwhich it causes the actuator to raise or lowerthetable, respectively; a ground sensor that senses the level of the ground and assumes a median position when the table is at a predetermined set height above the ground and moves either side of the median position with changes in ground level; a linkage connecting the ground sensor to the control element so that when the ground sensor isinthe median position the control element is in the neutral position, and movement of the sensor from the median position, caused by a rise in ground level, moves the control element to the raise position; an automatic mode selection lever that is movable between ON and OFF position and is connected via a spring connection to said linkage so that when in the ON position, the spring connection urges the linkage in that sense to cause the control element to move to the lower position, and when in the OFF position, the spring connection does not act on the linkage.

The linkage connects the ground sensorto the control element so that a RAISE signal can be transferred at all times, butfull automatic control is only operative when the selection lever is setto the ON position, thereby allowing the spring connection to give a spring return action for lowering the table to said predetermined height. Thus, a simplified system is provided that avoids the need for an uncoupling mechanism between the ground sensor and the control device. Further, the separate selection lever allows the return spring action on said linkage to be removed so thatthe table can be controlled in a unidirectional or raise mode in which it is held at a higher level over rough ground.

The invention will now be described by way of example with reference to the accompanying draw ings in which:- Figure lisa side elevation ofthe table atthefront of a combine harvesterfitted with an automatic table height control system according to the invention; Figure2 is a side elevation of part of the control system of Figure 1 that is connected to the table; Figure 3 is a front elevation of the control console of the combine of Figure 1; Figure4is a side elevation ofthe control console of Figure3; and Figure 5is a section along the line 5-5 in Figure 3.

The combine harvester illustrated in Figure 1 comprises a self-propelled vehicle 1 having a forwardly projecting crop elevator 2 that carries a crop cutting and gathering table 3 across the front of the vehicle.

The elevator 2 is pivotally connected to the vehicle frame and is moved about its pivot axis 4 by hydraulic rams 5 so asto adjust the height ofthetable 3 above the ground.

A control valve 6 controls hydraulicfluid connectins to the rams 5 for raising and lowering the table 3.

A manually operable control lever 7 is connected via a linkage 8to the spool 9 ofthe controlvalve6 so that the spool can be depressedto lowerthetable and liftedto raise the table. Centring springs within the valve urge the spool to a neutral position in which it isolates the rams from the hydraulic supply and exhaust.

The height of the table above the ground can also be controlled automatically by a height control system comprising ground sensors lOon the underside of the table and a mechanical linkagethatconnectsthe sensors 10 to the spool 9 ofthe control valve.

The ground sensors 10 may be ofa known kind comprising a plurality of rearwardly projecting curved fingers 1 1 that 11 thatarespacedacrossthewidthofthetable and are connected to a transverse pivot rod 12 attheir leading ends and are supported attheir rear ends by respective guide rods 13 that are pivotally connected to the fingers 11 and extend rearwards therefrom The drawing(s) originally filed was (were) informal and the print here reporduced is taken from a later filed formal copy.

The claims were filed later than the filing date within the period prescribed by Rule 25(1) of the Patents Rules 1982.

through apertures in a transverse support member 14 on the underside of the table. A stop 15 at the end of each rod 13 engages the support member 1 4to supportthe fingers 11 in a lowermost position when the table is lifted clearofthe ground. lfthetable is lowered far enough to bring one or more of the fingers 11 into contactwith the ground, these fingers will pivot in response to variations in ground level as the combine advances, and this movement is transferred from the pivot rod 12 through a projecting arm 16 and a rearwardlyextending connecting rod 17toa bell-crank lever 1 8that is pivotally mounted on the rearwall ofthetable (Figure 2).

A Bowden cable 19 connects the bell-crank lever 18 to the spool 9 ofthe control valve 6. The lower end of the inner cable 20 (Figure 2) is connected to the lever 18via a set of pivot links 21 and the upper end of the inner cable (Figure 3) is connected to one end of a lever 22 that is connected to the spool 9 at its opposite end.

The lower end oftheoutercable23 is connectedto a pivot arm 24 that is mounted on the rear wall of the table and is held in position by a spring-loaded stay 25 incorporating a compression spring 26. The upper wend ofthe outer cable 23 is connected via a bracket 27 to one end of a height control lever28that is adjustable in a quadrant (Figure 4) and serves to set the upper end of the outer cable in a position corresponding to a required table height above the ground. It will be appreciated thatthe setting of height control lever 28 determines the curvature of the cable 19 between this lever and the lower pivot arm 24, and thus the effective length ofthe inner cable 20 between the bell-crank lever 18 andthe lever22.Thus, when the height control systems is in operation with the fingers 11 in contactwiththeground and the lever22 holding the spool ofthe control valve 6 in its neutral position isolating the rams 5 from the hydraulic supply and exhaust, the length of the inner cable 20 set by the height control lever 28, determines the effective sensing position of the fingers 11 relative to the table, and thus the heightofthetable.

An automatic mode selection lever 30 is connected to the lever 22 via a tension spring 31 and serves, when in the ON position, to apply a spring bias to the lever that overcomes the spool centring springs and urges the spool ofthe control valve 6 downwards to the "table lower" position. When the selection lever 30 is in the OFF position, the lever 22 is free from the bias of spring 31.

Thus, when the table is raised, movement of the selection lever 30 to the ON position tensions spring 31 and pivots lever 22to depress the spool of the control valve 6, thereby connecting the rams 5to exhaust so thatthey lowerthetable. When the fingers 11 touch the ground they swing upwards and operate through arms 16, rod 17, bell-crank 18 and links 21 to pull on the inner cable 20, thereby pivoting lever 22to lift the spool ofthe control valve 6 backto its neutral position in which it isolates the rams 5. Thetable is then held atthis height until the fingers 11 move in response to avariation in ground level.

A rise in ground level will swing the fingers upwards and cause the spool ofthe control valve 6to be lifted further beyond the neutral position to the "table raise" position in which the rams 5 are connected to pressure and thus raisethetable. Thefingers can then swing backto their previous median position and the spring 31 returns lever 22 and the spool of the control valve to the neutral position.

Adrop in ground level will allowthefingersto swing further downwards, releasing the tension in cable 20 and allowing the spring 31 to return lever 22 and the spool of the control valve to the"table lower" position. The rams therefore lowerthe table until the fingers are returned to their previous median position with the cable 20 holding the lever22 and spool of the control valve in the neutral position.

When the automatic height control system is operating with the selection lever 30 in the ON position, the operator can still over-ride the height setting by operating the manual control lever7. If lever 7 is operated to lowerthetable,the spool of the control valve is depressed through linkage 8 and causes lever 22 to pivot and tension cable 20.

Additionally, cable 20 is tensioned bythe upwards movement of fingers 11 asthetableislowered.This tension is accommodated by movement of the pivot arm 24 againstthe action of compression spring 26, which in turn allows outer cable 23to straighten causing an effective increase in the length of the inner cable 20. On the other hand, if lever7 is operated to raise the table, the spool of the control valve is lifted through linkage 8 and causes lever 22to pivot and furthertension spring 31. Oncethe manual control lever 7 is released, the automatic control system resumes control and returns the table to the preset height.

It will be appreciated that the spring-loaded pivot arm 24 by allowing an effective increase in the length of cable 20 againstthe action of compression spring 26, serves both an over-ride and a safety function in allowing the fingers 11 to pivot upwards suddenly over an obstruction. Moreover, the loading of the compression spring 26 being adjustable through the lock nuts 32, provides the means to vary the sensitivity of the system in response to movementofthe fingers.

If the selection lever 30 is returned ta the OFF position, the table will remain in its lowered state. The resulting removal oftension in spring 31 may cause a minor readjustment of lever 22, cable 20 and fingers 11 that will cause the ramsto raise the table slightly.

Thereafter, thetable will be maintained atthis level until the fingers are raised,whereupoflthe tension transmittedthrough the cable 20 will operate lever 22 and thereby the spool of the control-valve to r & ethe table. Once raised, the spool of the controivatve is returned to the neutral position by the centring springs and the fingers return.totheir median position. The table isthus maintained at its new height. The absence of the spring action 31 now leaves some slackness in the cable 20 and thusthe fingers will not be effective in operating the lever 22 unless they are raised more than before so as to firsttake-up this slackness. The control system therefore operates in an automatic unidirectional or raise mode in which the table is lifted and held at a higher level if fingers sense rough ground or other uneveness or obstruc tions. The table is not repeatedly dropped back to the predetermined set height as in the fully automatic control mode when the selection lever 30 is in the ON position. Thus, the crop cutting knife 33 atthe leading edge of the table is held clear of obstructions.

Claims

1 An automatic table height control system for maintairting the height of a crop cutting table of a crop harvesting machine at a predetermined level above the groundcomprising a control device adapted to control an actuatorfor raising and lowering the table, the control device including a movable control ele mentthatassuaiesa neutral position orraiseand lower positionseither side of the neutral position in each of which it-causes the actuator to raiseor lower the table, respectively; a ground sensor that senses the level ofthe ground and assumes a median position when the table is at-a predetermined set height above the ground and moves either side ofthe median position with changes in ground level; a linkage connecting the ground:sensorto the control element so that when the ground sensor is in the median position the control element is in the neutral position, and movementofthesensorfromthemedian position, caused by a rise in ground level, moves the control element to the raise position; and an automatic mode selection mechanism associated with the linkage and incorporating spring meansthat is effec tive when the mode selection mechanism isin an ON state to act on said linkageto move the control element to the lower position, characterised in that the linkage (16to 22) ispermanentlyconnectedtothe control element (9) and the mode selection mechanism (30,31) comprises a mode selection lever (30) that is movable between ON and OFF position and is connected via said spring means (31) to said linkage (22) so that when in the ON position, the spring means (31) urgesthe linkage (22) in that senseto move the control element (9) to lower position, and when in the OFF position, the spring means (31) does not act on the linkage (22).

2. A system as claimed in claim 1 in which the linkage (16to 22) includes a Bowden cable (19) comprising inner and outer coaxail cables (20,23), the inner cable (20) being connected atone end to the ground sensor (11) and at the other end to a return lever (22) which is connected in turn to the control element (9).

3. Asystem assjaimedinclaim 2 in which the spring means (31)sqmprises a tension spring that is connected to th*-returr,r,lever (22).

4. Asystem as;claii;ned in claim 2 or 3 in which said one end of the innen cable (20) is connected to the ground sensor (11 )'aa plurality of pivoted links (21).

5. Asystem as maimed in any one ofclaims 2 or4 in which the outer cable (23) of the Bowden cable (19) has thatend adjaeentthe control element (9) con nectedto the height of cut control lever (28) that is adjustable to vary the position of said end of the outer cable(23).

6 A systern as claimed in claim 5 which the outer cable has that end adjacent the g round sensor (1 1)connectedto a spring-loaded pivot arm t24) which can move against the force of its spring loading to allow straightening of the outer cable (23).

7. Asystem as claimed in claim 6 in which the spring-loading of the pivot arm (24) is provided by a spring (26), the loading of which can be adjusted by means (32).

8. Asystem as claimed in any one of the preceding claims in which a manually operable height control lever (7) is connected to the control element (9) so as to control the latter.

9. An automatic table height control system substantially as herein described with reference to the accompanying drawings.