GB2184798A

GB2184798A - Transmission for self propelled agricultural machine

Info

Publication number: GB2184798A
Application number: GB08628690A
Authority: GB
Inventors: Hans-Helmut Coenenberg
Original assignee: Claas KGaA mbH
Current assignee: Claas KGaA mbH
Priority date: 1985-12-02
Filing date: 1986-12-01
Publication date: 1987-07-01
Anticipated expiration: 2006-12-01
Also published as: DE3542500C2; DE3542500A1; FR2590850A1; FR2590850B1; GB8628690D0; GB2184798B

Abstract

A self-propelled agricultural machine has a driving engine (1) adapted to be coupled via a travel speed variator (2) and a clutch (4) to a non-synchromesh gear ratio change mechanism (6), the agricultural machine having a thrust wheel or dog-type shift mechanism with a switching device and an electrical control device (15) connected to rotary speed sensors on the shafts of the ratio change mechanism, and to a processor (13) which imparts an engaging clearance for a preselected ratio to the switching device. A control device for the clutch, variator and ratio change mechanism comprises a hand and/or foot lever (16) which is pivotable out of a transversely engaged midway position (O) through an unstable midway position (N) into a forwards positioning zone (V) and into a reverse positioning zone (R), being so connected through switching and auxiliary elements to the processor and to the device for controlling the clutch and gearbox that it is possible to derive from the position of the control lever in the reverse and forward zones a desired speed signal which operates the travel speed variator and in that pivoting of the control lever out of the midway position, a clutch engaging signal, and conversely upon pivoting of the control lever into the midway position a clutch disengaging signal, is generated. <IMAGE>

Description

SPECIFICATION Self-propelled agricultural machine The invention relates to a self-propelled agricultural machine.

A self-propelled agricultural machine having a non-synchromesh gear ratio changing mechanism is described in the Applicant's prior but as yet unpublished German Patent application P 34 21 582.4. A particular feature of this mechanism is an arrangement in which, when the gear ratios are to be changed, the most favourable moment for gear engagement is calculated by a processor as a function of various measured data having regard to a given time period required for the mechanism to perform each change of ratios.

In this case, clearance for gear engagement is always ascertained for a point in time which is ahead of synchronism of the gear shafts or gear wheels which have to be coupled to one another so that the teeth of these gear wheels have a minimal speed in relation to one another when they meet so that a sudden tooth-to-tooth engagement is avoided and a reliable tracking-in is guaranteed.

In spite of the advantages offered by the aforementioned applied to a non-synchromesh gear shift change mechanism, the operator is still responsible for all manner of actuating sequences which must be performed at specific times and in specified sequences and which diverge from the actual working pattern. Thus the arrangement disclosed in the aforementioned prior application does not provide the ease of operation which is achievable with the considerably more expensive hydrostatic transmissions used in agricultural machines. It is a particular problem that a clutch must be operated when changing between forward and reverse gears.

Therefore an object of the invention is to improve a self-propelled agricultural machine having a non-synchromesh gear ratio changing mechanism, so as to provide a means for operating this mechanism, and a method of operation, which is simular to that of hydrostatic propulsion drives, so that the operator has no difficulty switching over when changing from a machine which features hydrostatic drive to a machine which has a non-synchromesh gearbox, and finds both machines similarly easy to operate.

According to this invention a self-propelled agricultural machine, particularly a harvesting machine, such as a combine harvester, with a driving engine adapted to be coupled to a non-synchromesh gear speed change mechanism serving as a gearbox and operated by auxiliary power through a travel speed variator and a clutch, the gear shift mechanism comprising a thrust wheel or dog-type shift arrangement with a shifting device and an electrical control device connected to rotary speed sensors on the gear shafts which are to be coupled and to a processor which feeds to the switching device clearance for engagement of the relevant gear and so varies the instant of clearance as a function of variations in rotary speeds of the gear shafts and a constant switching time that clearance takes place at a predetermined relative speed of the gear wheels which are to be brought into engagement and prior to synchronism or stoppage, characterised in that the control device comprises a hand and/or foot lever which is movable out of a transversely engaging intermediate position through an unstable intermediate position into a forwards zone and a reverse zone being so connected through shifting and auxiliary elements to the processor and the means of operating the clutch and the gearbox that from the position of the control lever in the two positioning zones, a desired speed signal is derived which controls the auxiliary power drive of the speed variator and in that when the lever is moved out of the intermediate position, a clutch engaging signal, and upon movement of the lever into the intermediate position a clutch disengaging signal, is generated to control the auxiliary drive of the clutch through independent travel/time behaviour patterns and in keeping with the preselected gear.

A particular advantage of the invention is the logical operation of the drive control lever, in that with the lever in either of the respective positioning zones for forwards travel and reverse travel, changing the angular position of the control lever tends to change the speed of travel in whichever gear is engaged. It is most logical to arrange the positioning zone for forward travel ahead of that for reverse travel, the speed of travel in each direction being proportional to the angular displacement of the control lever from the midway position, in each respective zone.

The direction of travel is changed simply by shifting the control lever from one positioning zone through the midway position and into the other positioning zone. A fast shift of the control lever is also possible because the logical links and programme patterns of the electrical control device are advantageously chosen so that the gear ratios are changed in a way which is co-ordinated with the clutch in whichever is the calculated optimum pattern.

Beause the control lever conveys the desired value of the speed of travel to a control circuit by virtue of its position within the forwards or reverse travels zones, comparison of the desired and actual values allows the speed of travel to be adjusted to the desired value in accordance with the angular position or variation in angle of the control lever.

In an advantageous further development, the control lever is, in its intermediate position, fixed both in transverse movement and also in forwards and backwards movement by a click stop engagement which facilitates manual override. This provides for a marked separation of neutral, forwards and reverse travel positions so that in most cases any visual monitoring of the control lever position is unnecessary. Spring-loaded members which engage with the control lever in the midway position, make it wasy to find these engaged positions which offer manual override.

As the control lever preset engagement positions are overridden, the declutching and clutch engagement operations take place according to their own particular preset patterns; dis-engagement of the clutch occurs in each case at maximum positioned speed while clutch engagement takes place only in the neutral position at maximum positioning speed but for the rest clutch engagement takes place in at least two stages with initially rapid "take-up" of dead travel until the onset of "bite" whereupon, according to the gear ratio, the process is slowed down until there is a more or less slow increase in the force of application in order to avoid abrupt acceleration.With hydraulic clutch actuation, simple and per se known hydraulic and hydropneumatic means are adequate while the start and finish of these processes are signalled to the processor by simple monitoring switches.

Since the selection of travel direction is made via the control lever, then for the choice of the transmission ratio it is necessary only to have one gear selector lever, which does not require a reverse travel stage. Advantageously, a gear shift preselector system is provided which is actuated by a gear preselector lever, actuation of the gear preselector lever resulting in an automatic gear change. For this purpose, the gear preselector lever is connected to a gear change monitoring switch via which gear preselection can be so passed to the processor that whichever is the fixed or calculable gear shift pattern, namely the disengagement and re-engagement of the gears, can be triggered together with the subsequent re-engagement process.At the same time, the travel speed variator is advantageously brought into the slow travel position when the gears are disengaged so that after re-engagement it can attain the desired speed value corresponding to the control lever position.

In a further advantageous development of the invention, also the coupling range can be adjustable up to the minimum speed in the relevant gear. For this purpose, an auxiliary force actuated clutch pedal is provided which is used for fine positioning, sudden stoppings.

e.g emergency stops, or also for momentary stopping and re-starting and accelerating up to the preset speed. This clutch pedal is comparable to the so-called inching pedal provided with many hydrostatic drive systems.

All in all, this combination of features considerably simplifies the operation of a self-propelled agricultural agricultural machine with a non-synchromesh gear ratio changing mechanism, and also provides the following advantages: upon disengagement of the clutch, the travel speed variator is automatically cut out and switched on again after re-engagement of the clutch which takes place either by shifting the control lever beyond the midway position, by shifting the gear pre-selector lever or by actuating the clutch pedal through the associated logic circuits in the processor.It is possible even while travelling to change to another gear preselected via the gear preselector lever because also via the gear preselector lever, the automatic gear change pattern with declutching, idling, clearance of the new gear after the rotary speeds have dropped below the electronicaly ascertained clearance values to the point of engagement of the clutch after the new gear has been engaged, and finally the running up of the travel variator to the value determined by the control lever, can be triggered. When changing down, the driver can still if he wishes accelerate the gear shift pattern by braking until he almost comes to a standstill because then the gear shift "window" calculated by the processor is reached more rapidly for engagement of the relevant gear wheels.

The invention will now be explained in greater detail hereinafter with reference to an example of embodiment shown in the accompanying drawings, in which: Figure 1 is a diagrammatic view of the travel drive of a self-propelled harvesting machine with an associated actuating means; and Figure 2 is a plan view of the control lever guide in the actuating means according to Fig.

1.

In the drawings, the motive power of the machine is obtained from a central driving engine 1 which can also be utilised as a source of power for other machine functions. Through a travel speed variator 2, it is coupled to a gearbox 6, of which the input shaft can be isolated from the travel speed variator 2 by means of an intermediate clutch 4. The travel speed variator 2 can be actuated via an auxiliary drive 3 and the clutch 4 through an associated auxiliary drive 5, both auxiliary drives possibly being integrated into a hydraulic system.

Gear changes in the gearbox 6 are effected via shift rods 8 via a shift block 7 which is likewise incorporated into a hydraulic shift system controlled by an electrical control system. A drive shaft 9 connects the gearboxy 6 to the driving wheels 10 of the self-propelled harvesting machine.

The auxiliary power equipment is supplied through a central hydraulic pump 12 which can likewise be driven by the driving motor 1.

A distributor means 11 controls the individual auxiliary power devices 3, 5 and 7,8 as a function of electrical signals passed through electrical conductors 14 to positioning and valve members within the apparatus 11, which are not shown in greater detail.

The principal element of the electrical control device is a processor 13, the task of which is first and foremost, when there is to be a gear ratio change in the gearbox 6, to calculate whichever is the most favourable point of engagement according to the various measured data and a constant ratio-changing pattern within the entire switching device, a corresponding engagement clearance being passed through one of the conductors 14 to the distributor device 11 for the shift block 7 which triggers the gear change. The corresponding logic links and programme patterns of the processor make it possible with minimal additional outlay to provide an automatic gear change or change of direction of travel.

Control lines 23 link the processor 13 to switching and auxiliary elements 15 which are likewise not shown in detail in the drawings.

These switching and auxiliary elements 15 are operatively connected to a control lever 16 which may take the form of a foot lever or a hand lever, being disposed in the machine operator's convenient reach.

As Fig. 2 particularly shows, the control lever 16 is guided in an elongated slide 24 in the middle of a long side of which there is a cut-out 25 which can be engaged by transverse displacement of the control lever 16 in relation to the longitudinal axis of the slide 24. By an opposing spring loaded ball 26, the control lever 16 is pressed into the cut-out 25. The position shown illustrates the engaged midway position 0 of the control lever 16 out of which, against the force of the spring loaded ball 26, it can be displaced transversely into a midway position N by transverse displacement towards the ball side, and out of which it can be moved in either of two directions along the slide 24. The natural position N is consequently unstable, requiring the control lever 16 to be held when so positioned, if movement out of position N is to be avoided.

The control lever 1 6 can be moved out of the unstable neutral position into the forwards travel zone Vv or into the reverse travel zone VR, either the maximum forwards speed Vv max or the maximum reverse speed VR max being provided in the respective extreme positions. The position for minimum speeds in both forwards and reverse travel zones, in other words Vv min or VR min are fixed by the control lever 1 6 resting on the ball 26 engaged transversely into the slide 24.

In the midway position 0 or N of the control lever 16, furthermore, a shift signal is triggered via a switching member 27 in order to actuate the clutch 4. With the lever 16 in other positions, other switches and switching members (not shown) are provided in order to transmit the corresponding direction of travel command via the processor 13 to the distributor device 11 and to the gearbox 6 for selection of the forwards and reverse gear.Furthermore, it is possible via the switching member 27 to ensure that if the control lever 16 is left in the engaged midway position 0, then when the shift mechanism actuality achieve its neutral mode, the clutch 4 is re-engaged so that the gearbox input shaft remains in movement to faciliate the next gear engagement, so that on the other hand unnecessarily long disengagement times of the clutch 4 with their stressing of hydraulics and mechanics can be avoided.

For this problem, the shift member 27 with the associated switch can also be available if, for the rest, other suitable switching elements are provided on the mechanical part of the control lever 16 to generate the clutch signal.

By virtue of its position within the forwards positioning zone Vv and reverse positioning zone VR, the control lever 16 provides a desired speed value as a function of which the travel speed variator 2 is controlled via the processor 13 and the distributor device 11.

By means of a feedback system, the desired and actual speed values are compared: this control arrangement makes is possible, regardless of the speed at which the control lever 16 is moved, to always adjust to the optimum adjustment speed of the travel variator 2.

Therefore, it is also possible to shift the control lever 16, practically instantly without overstraining the workings of the travel speed variator, during the subsequent shifting operation and the raising of the travel speed variator to the speed required. When the midway position N of the control lever 16 is reached, a disengagement signal is also passed to the clutch 4 and the clutch is not engaged again by the auxiliary drive 5 until the control lever 16 is moved out of the unstable midway position N transversely into the neutral position 0, or forwards or backwards along the slide 24, so producing a corresponding engagement signal.When the control lever 16 is moved from full deflection of the forwards zone V into a full deflection in the reverse zone R, there is first of all a reduction in the travel speed variator 2 down to the slow position and then the clutch 4 is disengaged, after which the gear change takes place in the gearbox 6 according to the gear shift "window" calculated by the processor 13, after which the clutch 4 is engaged and only afterwards is the speed variator caused to increase speed of travel.

In the immediate vicinity of the control lever 16 there is a gear preselector lever 17 through which it is possible not only to predetermine the gear to which the gearbox 6 is required to change-but also to trigger a gear change. For this purpose, the gear preselector lever 17 is coupled to a gear change monitoring switch 18 which, when the gear preselector lever 1 7 is actuated, brings about the subsequent part of the operating cycle: changing down of the travel speed variator 2, disen gagement of the clutch 4, changing of the gear ratio in the gearbox 6 via the shift block 7 and shift rods 8, engagement of the clutch 4 and raising of the travel speed variator 2 to the preset speed signalled by the angular position of the control lever 16.

The travel speed variator 2 cannot cover the entire speed range from zero travel speed up to whichever is the minimum speed of the gear engaged. Therefore, in addition to the control Iver 16 and the gear preselector lever 17, there is also a clutch pedal 20 coupled to a switch 21 which, when the clutch pedal 20 is operated, disengages the clutch 4 via the electrical control device. Furthermore, the clutch pedal 20 is connected via a hydraulic linkage 22 to the auxiliary power device 3 of the travel speed variator 2 in order to step the travel speed variator 2 down into the slow position before the clutch 4 is disengaged.

When the clutch pedal 20 is released, firstly the clutch 4 is engaged and only then is the speed variator 2 run up again to the envisaged speed.

Claims

1. Self-propelled agricultural machine, particularly a harvesting machine, such as a combine harvester, with a driving engine adapted to be coupled to a non-synchromesh gear speed charwermechanism serving as a gearbox and operated by auxiliary power through a travel speed variator and a clutch, the gear shift mechanism comprising a thrust wheel or dog-type shift arrangement with a shifting device and an electrical control device connected to rotary speed sensors on the gear shafts which are to be coupled and to a processor which feeds to the switching device clearance for engagement of the relevant gear and so varies the instant of clearance as a function of variations in rotary speeds of the gear shafts and a constant switching time that clearance takes place at a predetermined relative speed of the gear wheels which are to be brought into engagement and prior to synchronism or stoppage, characterised in that the control device comprises a hand and/or foot lever (16) which is movable out of a transversely engaging intermediate position (0) through an unstable intermediate position (N) into a forwards zone (V) and a reverse zone (R) being so connected through shifting and auxiliary elements (15) to the processor (13) and the means of operating the clutch and gearbox that from the position of the control lever (16) in the two positioning zones (V, R), a desired speed signal is derived which controls the auxiliary power drive (3) of the speed variator (2) and in that when the lever (16) is moved out of the intermediate position (N), a clutch engaging signal, and upon movement of the lever (16) into the intermediate position (N) a clutch disengaging signal, is generated to control the auxiliary drive (5) of the clutch (4) through independent travel/time behaviour patterns and in keeping with the preselected gear.

2. Self-propelled agricultural machine according to claim 1, characterised in that the control lever (16) when in the midway position (0) which is to be engaged is fixed traversely and longitudinally in relation to the forwards or reverse positions by click-stop engagements which facilitate manual override and in this click-engagement midway position (0), the clutch is re-engaged in the neutral position of the gear mechanism.

3. Self-propelled agricultural machine according to claim 1 or 2, characterised in that there is close to the control lever (16), a gear preselector lever (17) which is connected to the shifting and control device and the processor (13) via a gear preselector shift arrangement.

4. Self-propelled agricultural machine according to claim 3, characterised in that the gear preselector lever (17) is connected to a gear change monitoring switch (18) which so controls the processor (13) that in addition to the shifting cycle when the gears are changed, positioning signals for the preceding disengagement and subsequent re-engagement of the clutch (4) are generated and passed on to the auxiliary drive (5).

5. Self-propelled agricultural machine according to claim 4, characterised in that indirectly through the processor (13) or through its control means the travel speed variator (2) is adjusted via its auxiliary drive (3) prior to disengagement of the clutch (4) in that the speed variator 2 is moved into the slow position and after re-engagement of the clutch (4) it is adjusted to the travelling speed corresponding to the position of the control lever (16).

6. Self-propelled agricultural machine according to one of claims 1 to 5, characterised in that in addition to the control lever (16), a clutch pedal (20) is provided which, via a switch (21), controls the auxiliary drive (5) of the clutch (4) and through which, throughout the clutch operating process, the travel speed variator (2) is set to the slow speed via the auxiliary drive (3).