JP2781077B2 - Tractor draft control mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a draft control mechanism for keeping the traction force of a working machine mounted on a tractor constant.

[0002]

2. Description of the Related Art A conventional draft control device is disclosed in
This was configured as described in JP-A-20524. That is, the pushing force applied to the top link portion of the three-point link type working machine mounting device presses the draft sensor rod biased by the spring, and the draft sensor rod mechanically moves the hydraulic valve for lifting and lowering the working machine. By switching, the work machine is raised when the traction force is large, and the work machine is lowered when the traction force is small, so that the draft force is controlled to be constant.

[0003]

According to the present invention, as described in the prior art, a pressing force applied to a top link mechanically is obtained.
Rather than moving the draft sensor rod and switching the lift valve, the draft force is electronically detected by an electronic governor mechanism, and the working machine lift valve constituted by the electromagnetic switching valve is switched. As a result, the draft sensor rod conventionally mechanically configured can be eliminated, and a large urging spring provided at the end of the top link on the tractor side, or a connection between the switching valve and the draft sensor rod can be achieved. The configuration is such that a complicated configuration can be deleted.

[0004]

The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described. That is, the rotation number detection sensor 1 and the rack position sensor 2
Electronic governor mechanism A constituted by an actuator, a rack actuator 9 and an electronic control unit G;
, An accelerator lever sensor 5, a load factor setting device 6, and a lift angle sensor 3, and the detected load factor FS detected by the electronic control unit G in the working state is the set load factor set by the load factor setting device 6. In a configuration in which the working machine is controlled to move up and down so as to be within the setting range of F, the draft control is configured to be temporarily stopped when the engine speed is changed by the accelerator lever 14 or other control means. is there. Further, when the engine speed N is changed by the accelerator lever 14 or other control means, the draft control is suspended or temporarily stopped until the load ratio becomes substantially equal to the load ratio immediately before the change. The draft control is configured to stop when the vehicle stops running, when low idling is set, when starting, when the engine stalls, and when the engine is stopped. Further, the control interval of the draft control is made longer as the set load factor F becomes larger. Also,
The larger the set load factor F, the wider the dead zone width of the draft control.

[0005]

Next, the operation of the present invention will be described. In the conventional draft control mechanism, a mechanical sensor mechanism provided at the top link portion, a link and an arm, and the hydraulic switching valve is controlled by a feedback mechanism, but in the case of the present invention, The detection of the detected load factor FS is performed by the electronic governor mechanism A, the setting of the load factor is performed by the load factor setting device 6, and all the signals are obtained as electronic signals to enable the draft control. Although the electronic governor mechanism A is originally an electronic control mechanism for automatically controlling the rotation speed, load factor, and fuel supply amount of the engine E, the present invention uses the electronic governor mechanism A as a control component for draft control. By using it as a part, a draft control with a simple structure and all of it was made electronic. In such a draft control mechanism, since the electronic governor mechanism A is also used as the detection load rate FS detection mechanism, the detected load rate FS greatly changes while the engine speed N changes. If comparison control is performed between the detected load factor FS and the set load factor F, abnormal control will be performed. In the present invention, the draft control is stopped when the engine speed N changes so that such abnormal control does not occur. When the set load factor F is large,
The duty ratio of the pulse for driving the lift lifting / lowering electromagnetic valves V1 and V2 is changed to increase the control interval and to increase the dead zone width H.

[0006]

Next, embodiments of the present invention will be described. 1 is a side view of a tractor equipped with a rotary tilling device as a working machine, FIG. 2 is a side sectional view of an electronic governor mechanism A, FIG. 3 is a side view of the electronic governor mechanism A, and FIG. Drawing showing an example of the map, FIG. 5 is a hydraulic circuit diagram of a working machine lifting mechanism B having lift lifting / lowering solenoid valves V1 and V2.

Referring to FIG. 1, the structure of the tractor will be described.
An engine E is disposed inside the hood of the tractor, and an electronic governor mechanism A is attached to a side surface of the engine E. An accelerator lever 14 for setting the engine speed N by an operator is rotatably supported by a dashboard portion of the hood, and an accelerator lever sensor 5 is arranged at a base of the accelerator lever 14. The accelerator lever sensor 5 detects how much the operator has turned the accelerator lever 14 and how much rotation speed the operator desires to set. As a result, the engine speed N changes. Further, the engine speed N may be changed by another control. A work machine control panel 15 is provided on the side of the tractor seat. The work machine control panel 15 has an automatic / manual switch 8 for switching between automatic control and manual control of the work machine, A load factor setting device 6 for setting the load factor and a work implement position setting device 7 for setting the position of the work implement during position control are arranged. Further, the rotary tillage device R mounted on the rear of the tractor is provided with a tillage depth sensor 4 for detecting the tillage depth of the rotary tillage device R during the depth control of the working machine. Lift arm 13 for position control
The lift angle sensor 3 is arranged at the base of the.

The electronic governor mechanism A will be described with reference to FIGS. The electronic governor mechanism A is attached to a side surface of the engine E, and the magnetic rotating body 12 is fixed to a cam shaft 16 of the fuel pump. The rotation of the camshaft 16 is detected by the rotation speed detection sensor 1 of the magnetic rotator 12 to obtain the engine rotation speed. The fuel supply amount of the electronic governor mechanism A is adjusted by moving the fuel rack 10 from side to side. It is the rack actuator 9 that drives the fuel rack 10 based on the control command signal. The rack position sensor 2 detects the position of the fuel rack 10 moved by the rack actuator 9 and detects the fuel supply amount. A rack bar 11 connected to a fuel rack 10 is inserted through the rack position sensor 2 and the rack actuator 9.

Next, a control curve of the engine E by the electronic governor mechanism A will be described with reference to FIG. In the engine E, the engine output and the shaft torque are determined by the injection amount and the injection timing of the fuel injection pump and the engine speed. The fuel injection amount is adjusted by sliding the fuel rack 10 by the rack actuator 9. And it is obtained by measuring the injection amount based on the position of the fuel rack 10 and the engine speed. The injection timing is adjusted by a timing adjustment actuator (not shown).
The engine speed is detected by a speed detection sensor 1. The accelerator lever 14 of the operator is provided to the electronic control unit G.
Is rotated, the rotation speed is supported via the accelerator lever sensor 5. As the electronic control unit G, a microcomputer is used, and a program ROM storing a control program is arranged. In addition, a data ROM storing various data required for control calculation such as speed fluctuation rate characteristics is arranged.

In the data rom, what is the set value of the engine speed arbitrarily set according to the position of the accelerator lever 14 operated by the operator himself and the actual speed (actual value) according to the load. Such a speed variation characteristic is stored in the form of an arithmetic expression or a numerical table for each different work content. Regarding the speed fluctuation rate, the set value and the actual value of the period rotation speed are recognized, then the mode set by the operator is recognized, and the target rack position to be set is calculated by the droop rate map according to the mode. . A signal for changing the actual rack position to the corrected target rack position is output to the rack actuator 9, the fuel rack 10 is automatically adjusted, and the operation is performed within a predetermined speed fluctuation range. Normally, control is performed along the map d of the droop control shown in FIG. 4 so as to recognize a predetermined speed fluctuation, the fuel rack 10 changes, and the shaft torque changes.
The speed fluctuation characteristic is selected according to the mode of the work content. When constant rotation operation is required, the fuel consumption is increased or decreased and the rotation speed is made constant along the map i of the isochronous control in order to keep the rotation speed constant. , A constant rotation operation is performed. In addition, even in the case of isochronous control, especially in the case of special work, when the load increases and it is close to the maximum shaft torque, the reverse droop that increases the rotation speed and the shaft torque to prevent engine stall. It is also possible to select a control map r.

FIG. 5 shows a hydraulic circuit diagram of the working machine elevating mechanism B. The lift arm 13 is turned up and down by the expansion and contraction of the hydraulic cylinder 20,
Is provided with a lift angle sensor 3 for detecting the position. The lift hydraulic control valves V1 and V2 control the pressure oil to the hydraulic cylinder 20, and are constituted by a lift electromagnetic valve V1 and a downward magnetic valve V2. A signal for switching between the ascending solenoid valve V1 and the descending solenoid valve V2 is transmitted from the lift electronic control unit C.

FIG. 6 is a flow chart of a draft control mechanism showing the technology of the present invention, and FIG. 7 is a diagram showing a section between an electronic control section G of the electronic governor mechanism A, a lift electronic control section C, and a work implement elevating mechanism B. 3 is a diagram illustrating the movement of the detection signal and the command signal. In FIG. 7, the technique of claim 1 will be described. An electronic governor mechanism A including a rotation speed detection sensor 1, a rack position sensor 2, a rack actuator 9, and an electronic control unit G;
, An accelerator lever sensor 5, a load factor setting device 6, and a lift angle sensor 3, and the detected load factor FS detected by the electronic control unit G in the working state is the set load factor set by the load factor setting device 6. This is a technique for controlling the lifting and lowering of the working machine so that the working machine falls within the setting range of F. As shown in FIG. 7, signals are communicated between the electronic control unit G and the lift electronic control unit C of the electronic governor mechanism A, and the signals are also transmitted between the lift electronic control unit C and the work implement elevating mechanism B. Being communicated. The essential part of the present invention is that the signal of the electronic governor mechanism A can be used as a control signal of the work implement elevating mechanism B. That is, the electronic governor mechanism A and the work implement elevating mechanism B are connected via the lift electronic control unit C.

Next, FIG. 6 will be described along a flowchart. After the "start" of the control, "initial setting"
I do. Next, "The ascending solenoid valve V1 and the descending solenoid valve V2 are turned off.
F ". Next, "check of sensors" is performed. Next, it is determined whether or not the check result is OK. If “OK”, it is determined whether the automatic / manual switch 8 is “auto / manual”. If "manual", position control is performed. "Automatic"
If so, the “detected load factor FS” is read. Next, it is determined whether the working machine is in the “working state”. If not in the working state, the operation shifts to position control. If it is in the working state, it is next determined whether or not the output value of the accelerator lever sensor 5 has changed. If yes, after a certain period of time, it is again determined whether or not the output value of the accelerator lever sensor 5 has changed. This routine is repeated until a certain period of time elapses from the change in the number of revolutions by the accelerator lever sensor 5. Thus, the engine speed N
The draft control is temporarily stopped by waiting for a certain time from the change of the draft.

Then, when there is no change in the engine speed N, the detected load factor FS is read, and then the "set load factor F read" is performed. Next, "Read the dead zone width H"
I do. Then, the value of “HD · HS” obtained by increasing or decreasing the dead zone width H to the detected load factor FS is calculated. Next, it is determined whether or not “F> HD”. If “F> HD”, “the ascending solenoid valve V1 is turned ON”. If not “F> HD”, the ascending solenoid valve V1 is turned off. Next, “F <HS” is determined,
If “F <HS”, the descending solenoid valve V2 is turned ON. Unless “F <HS”, the descending solenoid valve V2 is turned off. If “HD <F <HS”, both the ascending solenoid valve V1 and the descending solenoid valve V2 are turned off.

Next, the technique of claim 2 will be described with reference to FIGS. FIG. 8 shows the case where the engine speed N is increased.
FIG. 9 is a flowchart showing the suspension of the draft control, and FIG. 9 is a drawing showing the suspension of the draft control when the engine speed N is reduced. In the technology of claim 1,
The draft control is started by monitoring the passage of a certain time from the change of the engine speed N by the accelerator lever 14, and the draft control is started.
4, the load ratio immediately before the change in the engine speed N is stored, and after the change in the engine speed N, the draft control is started only when the load ratio becomes close to the load ratio before the change. Things. Similarly, when the engine speed N is changed to the speed increase side or when the engine speed N is changed to the deceleration side, the draft control is temporarily stopped.

Next, referring to FIG. 10 and FIG. 11, the technique of claim 3 will be described. FIG. 10 shows a flowchart in a case where the draft control is stopped in the running stop state and the low idling rotation. FIG. 11 shows a flowchart in a case where the draft control is stopped at the time of starting, at the time of engine stall, and at the time of stopping the engine. When the tractor is stopped, the load factor of the engine E becomes small, and as the draft control of the work implement, the control is operated in the descending direction of the work implement, which is a direction in which the load increases, and the descending solenoid valve V2 is activated. The open state continues. Therefore, in order to solve such a problem, the draft control is disabled in the traveling stopped state.

Next, claim 4 will be described with reference to FIG. FIG. 12 shows that the set load factor F is divided into three stages of large, medium and small, and the non-control time of the pulse signal for opening and closing the lift lifting / lowering solenoid valves V1 and V2 is set to T1> T2 according to the magnitude of each set load factor F. > T3. Next, claim 5 will be described with reference to FIG. FIG. 13 shows the dead zone width H depending on whether the set load factor F is large, medium or small.
Can be changed to H1>H2> H3.
FIG. 14 is a flowchart in a case where the dead zone width H can be changed simultaneously with the magnitude of the set load factor F together with the pulse non-control time.

[0018]

As described above, the present invention has the following advantages. That is, the configuration described in claim 1 can solve the following problems. That is, when the engine speed N is changed by the accelerator lever 14, the load factor output from the electronic governor mechanism A is different from the actual load factor. That is, when the speed is increased, the load factor becomes large. This is because, in order to increase the speed, the supply amount of fuel is increased, and as a result, the rack position moves in the direction of a large load factor. Conversely, when the vehicle decelerates, the load factor decreases. This is because it is necessary to reduce the fuel supply amount in order to reduce the speed, and the rack position moves in the direction of the smaller load factor. If the draft control is performed in a state where the load factor is different from the actual value, the finished state after the work becomes uneven with many irregularities. Therefore, this problem can be solved by stopping the draft control while the engine speed N is changed.

[0019] Further, with the configuration as claimed in claim 2, the following problems can be solved. That is, when the engine speed N is increased by the accelerator, it is determined that the load factor is high. Actually, since the engine speed N is increased, it is determined that the load factor has become smaller, and the control in the opposite state is performed although the control should be performed accordingly. The same is true for deceleration. Therefore, this problem can be solved by temporarily stopping the draft control until the engine speed N returns to the load ratio before the change, as in the present technology.

[0020] Further, by configuring as in claim 3,
The electronic governor mechanism A detects a load factor different from the actual one,
If the draft control corresponding to this is performed as it is, the state that the lift elevating solenoid valves V1 and V2 are kept ON continues, and a problem that the instruction of the direction in which the working machine is lowered or the direction in which the work machine is raised continues. You do it. The present invention applies to all cases where such abnormal control may occur,
The problem was solved by stopping the control.

[0021] Further, with the configuration as claimed in claim 4, the following problems can be solved. The larger the load ratio of the engine E, the longer it takes to return to the set value,
When continuous control is performed, hunting occurs. In the present invention, such a disadvantage of the prior art can be solved by making the control interval longer as the load factor becomes larger and performing the control duller.

In addition, with the structure as claimed in claim 5, the precision is improved when the cultivation depth is reduced, and the variation is small when the cultivation depth is increased.

[Brief description of the drawings]

FIG. 1 is a side view of a tractor equipped with a rotary tilling device as a working machine.

FIG. 2 is a side sectional view of the electronic governor mechanism A.

FIG. 3 is a side view of the electronic governor mechanism A.

FIG. 4 is a diagram showing an example of a control map by an electronic governor mechanism A.

FIG. 5 is a hydraulic circuit diagram of a working machine elevating mechanism B including lift elevating electromagnetic valves V1 and V2.

FIG. 6 is a flowchart of a draft control mechanism of the tractor according to the present invention.

FIG. 7 is a diagram illustrating movements of a detection signal and a command signal among an electronic control unit G, a lift electronic control unit C, and a work implement elevating mechanism B of the electronic governor mechanism A;

FIG. 8 is a flowchart showing a temporary stop of draft control when the engine speed N is increased.

FIG. 9 is a drawing showing a temporary suspension of draft control when the engine speed N is reduced.

FIG. 10 is a flowchart in a case where draft control is stopped in a traveling stop state and during low idling rotation.

FIG. 11 is a flowchart in a case where draft control is stopped at the time of start, engine stall, and engine stop.

FIG. 12 divides a set load factor F into three stages of large, medium and small, and sets a non-control time of a pulse signal for opening and closing the lift elevating solenoid valves V1 and V2 to T according to the magnitude of each set load factor F.
It is a flowchart figure comprised so that it may change to 1>T2> T3.

FIG. 13 is a flowchart in which the value of the dead zone width H can be changed to H1>H2> H3 depending on whether the set load factor F is large, medium or small.

FIG. 14 is a flowchart in the case where the dead zone width H can be changed simultaneously with the magnitude of the set load factor F together with the pulse non-control time.

[Explanation of symbols]

 F Set load factor FS Detected load factor D Detected towing load DM Average calculated value A Electronic governor mechanism B Work implement elevating mechanism C Lift electronic control unit V1 Elevating solenoid valve V2 Descending solenoid valve H Dead band width T Non-control time 1 Rotation speed detection sensor 2 Rack position sensor 3 Lift angle sensor 4 Plowing depth position sensor 5 Accelerator lever sensor 6 Load factor setting device 7 Work implement position setting device 8 Automatic / manual changeover switch 9 Rack actuator 10 Fuel rack 11 Rack bar 12 Magnetic rotating body 20 Hydraulic cylinder

Claims (5)

(57) [Claims] 1. An electronic governor mechanism A including a rotation speed detection sensor 1, a rack position sensor 2, a rack actuator 9, and an electronic control unit G;
2, an accelerator lever sensor 5, a load factor setting device 6,
Equipped with a lift angle sensor 3 and an electronic control unit G
In the configuration in which the work implement is lifted / lowered so that the detected load factor FS detected by the above becomes within the set range of the set load factor F set by the load factor setting device 6, the engine speed is controlled by the accelerator lever 14 or other control means. A draft control mechanism for a tractor, characterized in that the draft control is temporarily stopped when is changed. 2. An electronic governor mechanism A including a rotation speed detection sensor 1, a rack position sensor 2, a rack actuator 9, and an electronic control unit G, and a lift elevating solenoid valve V1.V
2, an accelerator lever sensor 5, a load factor setting device 6,
Equipped with a lift angle sensor 3 and an electronic control unit G
In the configuration in which the work implement is lifted and lowered so that the detected load factor FS detected by the above-mentioned method falls within the set range of the set load factor F set by the load factor setting device 6, the engine speed is controlled by the accelerator lever 14 or other control means. A draft control mechanism for a tractor, wherein, when N is changed, the draft control is suspended or temporarily stopped until the load ratio becomes substantially equal to the load factor immediately before the change. 3. An electronic governor mechanism A including a rotation speed detection sensor 1, a rack position sensor 2, a rack actuator 9, and an electronic control unit G, and a lift elevating solenoid valve V1 · V.
2, an accelerator lever sensor 5, a load factor setting device 6,
Equipped with a lift angle sensor 3 and an electronic control unit G
In the configuration in which the working machine is controlled to move up and down so that the detected load factor FS detected by the above becomes within the set range of the set load factor F set by the load factor setting device 6, when the traveling is stopped, when the low idling rotation is set, and when the starting is performed, A draft control mechanism for a tractor, wherein the draft control is stopped when the engine stalls or when the engine is stopped. 4. An electronic governor mechanism A including a rotation speed detection sensor 1, a rack position sensor 2, a rack actuator 9, and an electronic control unit G, and a lift elevating solenoid valve V1.V
2, an accelerator lever sensor 5, a load factor setting device 6,
Equipped with a lift angle sensor 3 and an electronic control unit G
In the configuration in which the working machine is controlled to move up and down so that the detected load factor FS detected by the above becomes within the set range of the set load factor F set by the load factor setting device 6, the larger the set load factor F is, the more the draft control is performed. A draft control mechanism for a tractor, wherein the control interval of the tractor is extended. 5. An electronic governor mechanism A including a rotation speed detection sensor 1, a rack position sensor 2, a rack actuator 9, and an electronic control unit G, and a lift lifting / lowering solenoid valve V1 · V.
2, an accelerator lever sensor 5, a load factor setting device 6,
Equipped with a lift angle sensor 3 and an electronic control unit G
In the configuration in which the working machine is controlled to move up and down so that the detected load factor FS detected by the above becomes within the set range of the set load factor F set by the load factor setting device 6, the larger the set load factor F is, the more the draft control is performed. A tractor draft control mechanism characterized by a wider dead zone.