JP5011704B2 - Tractor travel control device - Google Patents

Description

  The present invention relates to a traveling control device for a tractor that controls a traveling speed by switching a working mode and a traveling mode by a changeover switch and adjusting an engine throttle opening and a transmission transmission ratio of a transmission.

As shown in Patent Document 1, there is known a tractor travel control device that controls an engine rotation and a transmission transmission ratio by switching between a work mode and a travel mode by a changeover switch signal. The work mode performs travel control at a set constant speed and is mainly applied for work travel. The travel mode performs travel control at a speed corresponding to the accelerator operation, and is mainly applied to mobile travel such as road travel.
JP 2003-74659 A

  However, the travel control device for the tractor needs to be switched to the travel mode by a switch operation when traveling outside the work in the middle of the tractor work in the work mode, and then again when returning to the work mode. Requires switch operation. Since such a troublesome switch operation is required, detailed response is difficult and the work efficiency is reduced. Even if a dedicated switch suitable for the switching operation is specially provided, the switch operation cannot be omitted, and conversely, the configuration becomes complicated.

  The problem to be solved is troublesome due to the simple configuration that does not require any special input tool in the tractor travel control device that controls the engine rotation and the transmission transmission ratio by switching the work mode and the travel mode by the changeover switch. An object of the present invention is to obtain a tractor travel control device capable of switching and returning modes at any time without requiring a switching operation.

According to the first aspect of the present invention, an output disk is arranged through front and rear power rollers between the front and rear input disks, and the rotational power of the engine received on the input disk is controlled by a transmission transmission ratio according to the angle of the power roller. A variator that outputs variable speed power from the output disk;
A planetary transmission unit which outputs the differential power of high and low with the variable speed power and the rotational power of the traveling transmission shaft as inputs;
It has a toroidal continuously variable transmission composed of a Hi-Lo clutch that switches the transmission of the high and low differential power,
Adjusting the throttle opening of the engine and the transmission transmission ratio of the toroidal continuously variable transmission to control the tractor's traveling speed, and to work at the set speed while operating the work equipment connected to the tractor so that it can be raised and lowered In a tractor travel control device comprising a control unit capable of switching between constant speed control and torque control for traveling at a vehicle speed corresponding to an accelerator operation,
The vehicle speed control by the control unit includes a speed selection switch for selecting from a plurality of set speeds, and a mode selection switch for selecting each mode of traveling, constant speed, roll baler, and traction work. Switching processing between the constant speed control and the torque control based on
In the above travel mode, torque control is performed with the reference vehicle speed set corresponding to the accelerator pedal operation position,
In the constant speed mode, constant speed control is performed at a constant speed according to the set speed corresponding to the selection of the speed selection switch, and torque control is performed when at least one of accelerator operation and work implement ascent is detected. It is characterized by constant speed control that travels at a set speed upon completion.
With the above configuration, even in the work mode, speed control is performed in the travel mode in accordance with the detection of the accelerator operation or the detection of the operation stop of the work implement. If the detected position of the accelerator pedal is detected and the detected value continues beyond a predetermined threshold value for a predetermined time or longer, the vehicle departs from the constant vehicle speed mode and shifts to speed adjustment by the accelerator pedal. When the value of is less than or equal to the threshold value, the vehicle speed can be changed only by operating the accelerator pedal without requiring a switch operation by speed control to return to the work mode.
In the invention according to claim 2, in the case of torque control by raising the work implement, only when the lift-up signal is input to the up state, when the lift-up signal is on the down side, the control is returned to the constant speed control. It is characterized by.
In the invention according to claim 3, in the brake processing in the vehicle speed control by the control unit , the brake switch left and brake switch right signals are input to the control unit, the vehicle speed control is performed by these signals, and the left and right brake switches are braked. A switch or potentiometer is attached to the pedal,
In addition, the control unit tries to obtain a geared neutral by controlling the ratio in the reverse deceleration direction only when the two-wheel brake is applied based on the signals of the left and right brake switches, and when the vehicle speed becomes below a certain level. Control is performed so that the clutch is released.
The invention according to claim 4 introduces a control process by a draft mode with a constant tilling depth in the draft work traveling of the tractor,
When the tilling depth constant draft mode is constant, the vehicle speed is changed according to the engine rotation by torque control, and when there is an excessive draft load fluctuation, a control process is performed to raise the work implement and apply the draft. Normal torque control is performed without applying a draft until a traction load reaches a certain value, and normal draft control is applied when a large traction load is applied. It is characterized by.

The tractor travel control device has the following effects.
When the travel mode is selected, travel control is performed at a vehicle speed corresponding to the accelerator operation. When the work mode is selected, travel control is performed at a set constant vehicle speed, and the accelerator operation is performed. If the working machine is not operated, the traveling control is performed at the vehicle speed corresponding to the accelerator position. Therefore, the travel control device for the tractor has a simple configuration that does not require any special input tool, so that mode switching and return can be performed at any time without requiring troublesome switching operations. It is possible to respond efficiently and finely. In addition, since the vehicle speed can be changed only by operating the accelerator pedal without requiring a switch operation, the operability and work can be improved.
According to the configuration of claim 2, in addition to the effect of claim 1, in the case of the lifting / lowering height of the work implement, when the lift-up signal is input to the rising state, the vehicle is temporarily released from the constant vehicle speed mode and is When shifting to speed adjustment and the lift-up signal goes down, the control returns to the work mode unrelated to the operation of the accelerator pedal, and at any speed while the work equipment is ascending without requiring switch operation. Since it can run, operability and workability can be improved.
In addition to the above configuration, the speed selected by the constant speed switch is set to the lowest speed, the vehicle speed in the work mode is maintained when the accelerator pedal is released during traveling by the accelerator pedal when the work machine is raised, and the vehicle is stopped by a brake operation. In such a case, since it operates as a speed increasing operation device when the pedal is depressed to the minimum speed or higher, operability and workability can be improved in turning the body and moving in the field.
According to the configuration of claim 3, in addition to the effects of claims 1 and 2, the two-wheel brake is used as a speed reduction in running on the road. It is possible to secure a braking force during road traveling without causing any trouble in traveling. In the above configuration, the turning torque during the operation can be secured by performing a control process for the one-side brake so as to increase the running torque.
According to the configuration of claim 4, in addition to the effects of claims 1 to 3, the constant tilling draft mode is a normal torque control without using the draft until a certain traction load, and a large traction load is applied. When entered, normal draft control is applied, vehicle speed control is performed except for excessive loads, and plowing depth is kept constant, so that work efficiency can be improved compared to conventional draft control with large plowing depth fluctuations. .

Embodiments specifically configured based on the above technical idea will be described below with reference to the drawings.
FIG. 1 is a side view of an agricultural tractor showing an example of a work vehicle equipped with a tractor travel control apparatus according to the present invention. The agricultural tractor 1 has an engine C mounted on the front part of the airframe having a front wheel A and a rear wheel B. The rotational power of the engine C is transmitted to the speed change transmission device 2 and is appropriately decelerated by the speed change transmission device 2. The power is transmitted to the front wheel A and the rear wheel B, and is also output to the rear working machine F via the rear PTO shaft E. The work machine F is supported by an elevating arm 54a tilted by the work machine elevating cylinder 54 so that the work machine F can be raised and lowered, and a rolling adjustment cylinder 53 is interposed so that the left and right heights of the work machine F can be adjusted.

  For operation by the operator, a monitor J for displaying the driving state on the front side of the steering handle H, a forward / reverse switching lever K and an accelerator lever L for switching forward and backward, an accelerator pedal M and a brake pedal N at the base, A shift lever Q and the like are arranged beside the cockpit P provided at the upper part of the transmission case 2a of the transmission 2 and configured to be automatically shiftable by the controller 61.

  As shown in FIG. 2, the transmission transmission apparatus 2 is provided with an input shaft 11 that receives power from the engine C in the previous stage, and the traveling system power is transmitted from the input shaft 11 to the traveling transmission shaft 12. Gear transmission. A variator 13 of a full toroidal type transmission mechanism that receives the input rotation of the traveling transmission shaft 12 and outputs shifting power is provided, and the planetary transmission that outputs high and low differential power with the shifting power and the traveling transmission shaft 12 as inputs. The part 14 and the drive pinion shaft 15d as an output thereof are configured on one line via the Hi-Lo clutch 15 for switching the transmission of the differential power of the high and low, and the rear wheel differential part 16 to the left and right rear wheels B The driving power is transmitted to Further, the driving power is branched from the drive pinion shaft 15d to the front wheel transmission shaft 17, and is connected to the front wheel differential portion 19 via the front wheel speed increasing clutch 18 for speed increasing transmission control, and the driving power is transmitted to the left and right front wheels A. . Further, a 4WD input rotation sensor 17r and an output sensor 18r are provided for vehicle speed detection.

  The work machine system power is transmitted from the input shaft 11 to the speed increasing gear by the PTO transmission shaft 21, branched to the hydraulic pump 23 via the bevel gear 22, and the PTO clutch 24 and the reverse clutch 25 are provided downstream of the PTO transmission shaft 21. And transmit to the PTO shaft E via the transmission ratio switching unit 26.

  The variator 13 includes an output disk 32 disposed between the front and rear input disks 31 and 31 that receive the rotational power of the traveling transmission shaft 12, and includes front and rear power rollers 33 and 33 therebetween. This is placed in a dedicated compartment in the transmission case.

  The differential output of the planetary transmission unit 14 is obtained by changing the forward / reverse rotational speed including the stop speed to the variator by the planetary gear that differentials between the planetary carrier that receives the input side rotation of the variator 13 and the sun gear that receives the output side rotation. It outputs according to 13 gear ratio. When stopping the airframe, the gear transmission can be configured without requiring a main clutch by controlling the power roller 33 of the variator 13 to move forward and backward to a geared neutral position where the gear ratio corresponds to the stop speed. it can. Further, at the time of starting the engine, start control including advance / retreat control to the geared neutral position is performed.

  As shown in FIG. 3, the tractor travel control device of the present invention has a mode changeover switch 73, a speed selection switch 74, an accelerator pedal sensor M, a lift-up signal 77, a vehicle speed on the input side of the control unit 71, as shown in FIG. The sensor 84 and the like are connected, and the roller solenoids 91s and 91t, the Hi clutch solenoid 92H, the Lo clutch solenoid 92L and the like are connected to the output side. A mode selector switch 73 switches between torque control for road driving mode and constant speed control for work mode, and a speed selection switch 74 selects a set speed in the work mode.

  The control unit 71 determines the reference vehicle speed based on the mode changeover switch 73 or the like operated by the operator, compares the actual vehicle speed with the vehicle speed sensor 84, and until the actual vehicle speed becomes equal to the reference vehicle speed, the roller solenoids 91s, 91t, Drive control of the Hi clutch solenoid 92H and the Lo clutch solenoid 92L is performed. The reference vehicle speed is determined by the mode changeover switch 73, the accelerator pedal sensor M, and the speed selection switch 74, and includes a lift-up signal 77 if necessary.

In addition, on the input side, linear shifts 72f and 72r, shift levers, roller pressure sensors 75s and 75t, HL clutch pressure sensors 76s and 76t, throttle sensor C1 , initial operation mode input 78, engine rotation sensor 81, oil temperature sensor 82, a variator output disk rotation sensor 83, a brake coupling sensor 85, a brake pedal sensor 86, and the like are connected.

Next, specific traveling control by the above configuration will be described.
The mode changeover switch 73 selects each mode such as “travel”, “constant speed”, and “roll baler” as shown in the changeover configuration diagram of FIG. “Traveling” is a selection position of a road traveling mode to which torque control for changing the vehicle speed according to the accelerator operation is applied, and “constant speed” is a setting corresponding to the selection of “1” to “3” of the speed selection switch 74. In principle, a constant speed control based on speed is used, and an exception is applied to a work mode with an exception to which torque control is applied under a predetermined condition. A “roll baler” is a selection position for baler mode control (described later).

  The predetermined condition in the work mode corresponds to the case where the accelerator pedal operation is detected, and if necessary, the case where the lift arm rise is detected, and torque control is applied under these conditions. Only when there is not, constant speed control by the set speed is performed.

  That is, as shown in the driving operation example of FIG. 5B, when the accelerator pedal is operated during driving at a constant speed based on the set speed, the work mode becomes the driving control corresponding to the pedal operation, and the pedal operation is performed. When is no longer present, constant speed control is performed again at the set speed. The presence or absence of the pedal operation is detected by detecting the position of the accelerator pedal, and when the pedal depression amount exceeds the set threshold value and the predetermined time t1 is continued, it is determined that the pedal operation is performed. Judge that there is no pedal operation. Further, as shown in the example of the traveling operation in FIG. 5C, torque control is performed when the lift arm is raised, and constant speed control is performed when the lift arm is lowered.

  The vehicle speed control process will be described in detail. In the road travel mode, as shown in the flowchart of FIG. 5, a reference vehicle speed corresponding to the accelerator pedal position is set (S1), and the actual vehicle speed is set for the reference vehicle speed corresponding to the pedal operation. The control unit 71 performs a process of changing the gear ratio (S2, S3) through the control valve for operating the power roller until they match. The vehicle speed is determined by the balance between the load and the driving torque, and the vehicle travels with the driving torque determined by the accelerator pedal.

  Further, in the work mode, as shown in the flowchart of the vehicle speed control process of FIG. 6, the set vehicle speed (for example, 2 km / h) by the speed selection switch 74 is set (S11), and the accelerator pedal operation or the lift arm is raised. In the determination (S12, S13), the power roller drive control (S14a) is performed so that the reference vehicle speed corresponding to the accelerator pedal position is obtained only when applicable, and the vehicle speed is set to the set vehicle speed when neither is applicable. Then, drive control of the power roller (S14b) is performed.

  As described above, when the depression position of the accelerator pedal is detected and the detected value is equal to or greater than a predetermined threshold and continues for a predetermined time or longer, the vehicle is temporarily departed from the constant vehicle speed mode and shifted to the speed adjustment by the accelerator pedal. When the value of the accelerator pedal is less than or equal to the threshold value for a certain period of time, the vehicle speed can be changed only by operating the accelerator pedal without requiring a switch operation by speed control to return to the work mode, so that operability and work can be improved.

  In the case of the lifting / lowering height of the work implement, when the lift-up signal is input to the up state, the constant vehicle speed mode is temporarily disengaged and the speed is adjusted by the accelerator pedal. By returning to the work mode unrelated to the operation of the accelerator pedal, it is possible to travel at any speed while the work implement is raised without requiring a switch operation, so that operability and workability can be improved. .

  In addition to the above configuration, the speed selected by the constant speed switch is set to the lowest speed, the vehicle speed in the work mode is maintained when the accelerator pedal is released during traveling by the accelerator pedal when the work machine is raised, and the vehicle is stopped by a brake operation. In such a case, since it operates as a speed increasing operation device when the pedal is depressed to the minimum speed or higher, operability and workability can be improved in turning the body and moving in the field.

  In the baler mode, constant speed control is normally performed by ratio control, and automatic change control is performed for torque control when the engine load increases and the engine speed decreases. When the roll baler work is applied to the slope, the engine rotation drops as the traveling load increases, and there is a problem that the PTO rotation decreases due to the influence, and the bale work itself becomes clogged, but by controlling as described above, Since the vehicle speed can be reduced by detecting the load, the operation speed on the work machine side can be kept constant, and the bale operation can proceed without causing clogging. In this case, the same effect as described above can be obtained by detecting the change in the rack position and automatically changing from the constant speed control to the torque control to reduce the vehicle speed in accordance with the load change.

  The vehicle speed detection in the vehicle speed control is controlled to use a value V obtained by subtracting the rotation of the output sensor 18r from the 4WD input rotation sensor 17r, as shown in the front wheel rotation characteristic diagram of FIG. By such control, the unevenness of the detection value of the 4WD input rotation sensor 17r that becomes unstable at the time of turning is corrected, and it is possible to reduce erroneous detection by smooth and stable data, so that a smooth resume change is possible. Shock reduction can be achieved.

  As for the brake processing in the vehicle speed control, as shown in the control system configuration diagram of FIG. 8, the signals of the brake switch left 87L and the brake switch right 87R are input to the control unit 71, and the vehicle speed control is performed by these signals. The left and right brake switches 87L and 87R are configured by attaching a switch or a potentiometer to the brake pedal.

  Based on the signals of the left and right brake switches 87L and 87R, the control unit 71 attempts to obtain a geared neutral by controlling the ratio in the opposite deceleration direction only when the two-wheel brake is applied, and the vehicle speed is reduced to a certain level. Then, it controls to drop the clutch. Since the two-wheel brake is used as a speed reduction in road driving, the braking process during road driving is ensured by performing the control process as described above without causing any trouble in turning driving during work by the one-side brake. be able to. In the above configuration, the turning torque during the operation can be secured by performing a control process for the one-side brake so as to increase the running torque.

  In the draft work traveling of the tractor, the control process by the draft mode with a constant tilling depth described below is introduced. In this constant tilling depth draft mode, when the tilling depth is constant, the vehicle speed is changed in accordance with the engine rotation by torque control, and when there is an excessive draft load fluctuation, a control process is performed to raise the work implement and apply the draft.

  In the above draft with constant tillage depth, normal torque control is performed without applying the draft until the traction load reaches a certain value, and normal draft control is applied when a large traction load is applied. Since the control is performed and the tilling depth is constant, the working efficiency can be improved as compared with the conventional draft control in which the variation in tilling depth is large.

It is a side view of the agricultural tractor which shows the example of application of the 2WD 4WD switching apparatus which concerns on this invention. It is a transmission system expansion | deployment figure of a transmission transmission part. It is a control block diagram of a traveling control apparatus. FIG. 4 is a switching configuration diagram (a) of the mode changeover switch and two example travel operation diagrams (b, c). It is a flowchart of the vehicle speed control process of driving mode. It is a flowchart of the vehicle speed control process in a work mode. It is a front wheel rotation characteristic view. It is a control system block diagram of a brake process.

DESCRIPTION OF SYMBOLS 1 Agricultural tractor 2 Variable speed transmission 13 Variator 31 Input disk 32 Output disk 33 Power roller 54 Work machine elevating cylinder 54a Elevating arm 61 Controller 71 Controller 73 Mode changeover switch 74 Speed selection switch 77 Lift up signal 81 Engine rotation sensor 84 Vehicle speed Sensor 91s, 91t Roller solenoid A Front wheel B Rear wheel C Engine F Work machine M Accelerator pedal (Accelerator pedal sensor)
t1 predetermined time t2 predetermined time

Claims (4)

An output disk is arranged between the front and rear input disks and the front and rear power rollers between them, and the engine rotational power received by the input disks is output from the output disk as the speed change ratio according to the angle of the power roller. With the variator,
A planetary transmission unit which outputs the differential power of high and low with the variable speed power and the rotational power of the traveling transmission shaft as inputs;
It has a toroidal continuously variable transmission composed of a Hi-Lo clutch that switches the transmission of the high and low differential power,
Adjusting the throttle opening of the engine and the transmission transmission ratio of the toroidal continuously variable transmission to control the tractor's traveling speed, and to work at the set speed while operating the work equipment connected to the tractor so that it can be raised and lowered In a tractor travel control device comprising a control unit capable of switching between constant speed control and torque control for traveling at a vehicle speed corresponding to an accelerator operation,
The vehicle speed control by the control unit includes a speed selection switch for selecting from a plurality of set speeds, and a mode selection switch for selecting each mode of traveling, constant speed, roll baler, and traction work. Switching processing between the constant speed control and the torque control based on
In the above travel mode, torque control is performed with the reference vehicle speed set corresponding to the accelerator pedal operation position,
In the constant speed mode, constant speed control is performed at a constant speed according to the set speed corresponding to the selection of the speed selection switch, and torque control is performed when at least one of accelerator operation and work implement ascent is detected. A tractor travel control device characterized by constant speed control that travels at a set speed upon completion.   In the case of torque control by raising the work implement, only when the lift-up signal is input to the up state, the control is returned to the constant speed control when the lift-up signal goes down. The tractor travel control device described. The brake processing in the vehicle speed control by the control unit is such that the signals of the brake switch left and brake switch right are input to the control unit, and the vehicle speed control is performed by these signals, and the toroidal continuously variable transmission is performed only when the two-wheel brake is applied. 3. The power transmission is controlled by the clutch of the toroidal continuously variable transmission when the transmission speed ratio is controlled to a stop speed by the machine and the vehicle speed becomes a certain level or less immediately before the stop. Tractor travel control device.   In the traction mode, when the working depth is constant, the vehicle speed is changed in accordance with the engine speed by torque control, and if there is an excessive draft load fluctuation, the work machine is raised to perform the control process to make the draft effective. 4. The tractor travel control device according to claim 1, wherein torque control is performed when the value is equal to or less than a certain value. 5.

Images