WO1984004652A1

WO1984004652A1 - Automatic header height control

Info

Publication number: WO1984004652A1
Application number: PCT/GB1984/000175
Authority: WO
Inventors: Cedric Sharpe
Original assignee: Massey Ferguson Sa; Massey Ferguson Services Nv
Priority date: 1983-05-31
Filing date: 1984-05-23
Publication date: 1984-12-06
Also published as: GB2141012A; FI850391A0; AU3016984A; EP0153321A1; GB2141012B; GB8314893D0; FI850391L

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

Automatic header height control

Field of the Invention

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

Background Art

Automatic table height control systems are known such as shown in British patent specification number 1 124 111 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 to variations in the ground 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 lever that is connected to the control valve. Automatic table height control is engaged by- a selection lever that serves to connect the Bowden cable to the manual control lever so that the sensing fingers operate the latter. Thus, manual or automatic table height control is possible depending upon whether or not the selection lever is coupled to 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 con¬ nection so that the manual control lever can be operated to raise the table without disengaging the selection lever. Release of the manual control lever then allows automatic control to resume. Disclosure of the Invention

An object of the present invention is to provide an improved automatic table height control system, in particular, a simpler system 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 for full automatic control but causes the table to be raised automat¬ ically and held at a higher level over rough ground condit¬ ions 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 of which it causes the actuator to raise or lower the table, respect¬ ively; a ground sensor 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 link¬ age connecting the ground sensor to the control element 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; 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 sensor to the control ele¬ ment so that a RAISE signal can be transferred at all times, but full automatic control is only operative when the selection lever is set to 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 that the table can be controlled in a uni¬ directional 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 drawings in which:-

Description of the Drawings

Figure 1 is a side elevation of the table at the front of a combine harvester fitted with an automatic table height control system according to the invention;

Figure 2 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;

Figure 4 is a side elevation of the control console of Figure 3; and

Figure 5 is a section along the line 5-5 in Figure 3.

Best Mode of Carrying Out the Invention

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 pivot- ally connected to the vehicle frame and is moved about its pivot axis 4 by hydraulic rams 5 so as to adjust the height of the table 3 above the ground.

A control valve 6 controls hydraulic fluid connections to the rams 5 for raising and lowering the table 3. A manually operable control lever 7 is connected via a linkage 8 to the spool 9 of the control valve 6 so that the spool can be de¬ pressed to lower the table and lifted to 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 con¬ trolled automatically by a height control system comprising ground sensors 10 on the underside of the table and a mechanical linkage that connects the sensors 10 to the spool 9 of the control valve.

The ground sensors 10 may be of a known kind comprising a plurality of rearwardly projecting curved fingers 11 that are spaced across the width of the table and are connected to a transverse pivot rod 12 at their leading ends and are supported at their rear ends by respective guide rods 13 that are pivotally connected to the fingers 11 and extend rearwards therefrom 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 14 to support the fingers 11 in a lowermost position when the table is lifted clear of the ground. If the table is low¬ ered far enough to bring one or more of the fingers 11 into contact with the ground, these fingers will pivot in re¬ sponse 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 rearwardly ex¬ tending connecting rod 17 to a bell-crank lever 18 that is pivotally mounted on the rear wall of the table (Figure 2) .

A Bowden cable 19 connects the bell-crank lever 18 to the spool 9 of the control valve 6. The lower end of the inner cable 20 (Figure 2) is connected to the lever 18 via 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 of the outer cable 23 is connected to a pivot arm 24 that is mounted on the rear wall of the table and is held in posi¬ tion by a spring-loaded stay 25 incorporating a compression spring 26. The upper end of the outer cable 23 is connected via a bracket 27 to one end of a height control lever 28 that 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 that the 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 of the inner cable 20 between the bell- crank lever 18 and the lever 22. Thus, when the height control system is in operation with the fingers 11 in contact with the ground and the lever 22 holding the spool of the 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 height of the table.

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 22 that over¬ comes the spool centring springs and urges the spool of the 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 22 to depress the spool of the control valve 6, there¬ by connecting the rams 5 to exhaust so that they lower the table. When the fingers 11 touch the ground they swing up¬ wards and operate through arm 16, rod 17, bell-crank 18 and links 21 to pull on the inner cable 20, thereby pivoting lever 22 to lift the spool"of the control valve 6 back to its neutral position in which it isolates the rams 5. The table is then held at this height until the fingers 11 move in response to a variation in ground level.

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

A drop in ground level will allow the fingers to 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 lower the table until the fingers are returned to their previous median position with the cable 20 holding the lever 22 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 lever 7. If lever 7 is operated to lower the table, 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 by the upwards movement of fingers 11 as the table is lowered. This tension is accommodated by movement of the pivot arm 24 against the action of compression spring 26, which in turn allows outer cable 23 to straighten causing an effective increase in the length of the inner cable 20. On the other hand, if lever 7 is operated to raise the table, the spool of the control valve is lifted through linkage 8 and causes lever 22 to pivot and further tension spring 31. Once the 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 against the 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 the lock nuts 32, provides the means to vary the sensitivity of the system in response to movement of the fingers.

If the selection lever 30 is returned to the OFF position, the table will remain in its lowered state. The resulting removal of tension in spring 31 may cause a minor re¬ adjustment of lever 22, cable 20 and fingers 11 that will cause the rams to raise the table slightly. Thereafter, the table will be maintained at this level until the fingers are raised, whereupon the tension transmitted through the cable 20 will operate lever 22 and thereby the spool of the control valve to raise the table. Once raised, the spool of the control valve is returned to the neutral position by the centring springs and the fingers return to their median position. The table is thus maintained at its new height. The absence of the spring action 31 now leaves some slack¬ ness in the cable 20 and thus the fingers will not be effective in operating the lever 22 unless they are raised more than before so as to first take-up this slackness. The

OMPI control system therefore operates in an automatic uni¬ directional or raise mode in which the table is lifted and held at a higher level if the fingers sense rough ground or other uneveness or obstructions. The table is not repeat¬ edly 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 at the leading edge of the table is held clear of obstructions.

Claims

1. An automatic table height control system for maintaining the height of a crop cutting table of a crop harvesting machine at a predetermined level above the ground 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 of which it causes the actuator to raise or lower the table, respectively; a ground sensor 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 connecting the ground sensor to the control element 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 associated with the linkage and incorporating spring means that is effective when the mode selection mechanism is in an ON state to act on said linkage to move the control element to the lower position, characterised in that the linkage (16 to 22) is permanently connected to the 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) urges the linkage (22) in that sense to 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 (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) .

3. A system as claimed in claim 2 in which the spring means

(31) comprises a tension spring that is connected to the return lever (22) .

4. A system as claimed in claim 2 or 3 in which said one end of the inner cable (20) is connected to the ground senso (11) via a plurality of pivoted links (21) .

5. A system as claimed in any one of claims 2 or 4 in which the outer cable (23) of the Bowden cable (19) has that end adjacent the control element (9) connected to the height of cut control lever (28) that is adjustable to vary the position of said end of the outer cable (23).

6. A system as claimed in claim 5 in which the outer cable (23) has that end adjacent the ground sensor (11) connected to a spring-loaded pivot arm (24) which can move against the force of its spring-loading to allow straightening of the outer cable (23).

7. A system 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. A system as claimed in any one of the preceeding 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.