JP5817291B2 - Shift control device for work vehicle - Google Patents

Description

  The present invention relates to a shift control device for a work vehicle in which a hydraulic continuously variable transmission (hereinafter referred to as “HST”) is provided in a traveling transmission system, and the traveling vehicle speed is adjusted by controlling the shift of the HST by a control unit.

  As shown in Patent Document 1, a work vehicle provided with a travel transmission system that has an HST transmission mechanism that continuously shifts HST forward and backward by trunnion control has a wide range of shift positions for adjusting the vehicle speed. 2. Description of the Related Art A shift control device for a work vehicle having a control unit that controls an HST transmission mechanism according to an operation position of a main transmission lever is known.

In this shift control device, the controller controls the drive shaft of the trunnion shaft according to the selected position of the main shift lever, thereby adjusting the output shaft rotational speed of the HST transmission mechanism.
More specifically, means for detecting the rotational position of the main transmission lever, means for detecting the rotational position of the forward / reverse switching lever, means for detecting the tilt angle of the movable swash plate of the hydraulic pump, tilt angle of the movable swash plate Is provided, and each means is connected to the controller and controlled so that the movable swash plate of the HST transmission mechanism is tilted to the operating direction of the forward / reverse switching lever and the speed set by the main transmission lever.

JP 2002-250437 A

  The shift control device for the work vehicle detects the shift position of the main shift lever with a sensor, drives the electromagnetic valve of the actuator with a drive current corresponding to the detected value, and sets the tilt angle of the movable swash plate of the hydraulic pump. Although it is changed, due to the play of the HST itself or the interlocking mechanism of the actuator and the movable swash plate, if the work vehicle is different, the tilt angle of the movable swash plate will not be the same even if the shift position of the main transmission lever is the same The running speed will be different.

  Accordingly, an object of the present invention is to travel at a constant traveling speed if the shift setting position of the speed change operation tool is the same even if the body of the work vehicle is different.

The problems of the present invention are solved by the following technical means.
According to the first aspect of the present invention, the movement of the transmission operating tool 18 is detected by the transmission position sensor 58, the engine speed is adjusted based on the detected value of the transmission position sensor 58, and the trunnion shaft of the HST 21 is rotated. In the shift control device for a work vehicle that achieves a set travel speed, the relationship between the drive current value and the output rotation speed of the HST 21 is examined in the adjustment mode for each machine body, and the detected value near the maximum output is decreased at a predetermined rate from the maximum output. Is stored in the control device 50 as control data, and is set by the speed change operation tool 18 using the control data. a structure for controlling the drive current of the solenoid valves 62 and 63 for rotating the trunnion shaft so that the rotational speed of the output shaft of HST21 corresponding to the speed, output the largest in the adjustment mode Detection of the maximum near the drive current value E and the drive start current value F of the rotational speed and the output start time near the detection value is a shift control device for a working vehicle, which comprises carrying out separately the forward side and the reverse side.

With this configuration, even if the maximum output varies and is unstable, if it is a detected value near the maximum output that has decreased at a predetermined rate from the maximum output, the relationship between the drive current and the rotational speed is reliably detected and converted to control data Even if the interlocking mechanism from the speed change operation tool 18 to the trunnion shaft of the HST 21 is different for each machine, the drive current value at the start of output stored in the adjustment mode and the drive current value near the maximum output can be used to change the speed. The electromagnetic valves 62 and 63 of the trunnion shaft can be controlled so that the HST 21 becomes the set rotational speed at the predetermined shift position of the operation tool 18 and travels at the set travel speed. Further, with this configuration, it is possible to detect the relationship between the drive current and the rotational speed that are different between the forward side and the reverse side and to generate control data, and to accurately control the traveling speed on the forward side and the reverse side.

According to the second aspect of the present invention, the movement of the transmission operating tool 18 is detected by the transmission position sensor 58, the engine speed is adjusted based on the detection value of the transmission position sensor 58, and the trunnion shaft of the HST 21 is rotated. In the shift control device for a work vehicle that achieves a set travel speed, the relationship between the drive current value and the output rotation speed of the HST 21 is examined in the adjustment mode for each machine body, and the detected value near the maximum output is decreased at a predetermined rate from the maximum output. Is stored in the control device 50 as control data, and is set by the speed change operation tool 18 using the control data. The drive current value of the electromagnetic valves 62 and 63 that rotate the trunnion shaft to control the output shaft rotation speed of the HST 21 corresponding to the speed is controlled, and the drive current at the start of output Of detection, the vehicle speed change control of the work vehicle and to store a drive current value when the vehicle has started to move gradually increasing a current value from a stopped state as the drive start current value F The device.

With this configuration, even if the maximum output varies and is unstable, if it is a detected value near the maximum output that has decreased at a predetermined rate from the maximum output, the relationship between the drive current and the rotational speed is reliably detected and converted to control data Even if the interlocking mechanism from the speed change operation tool 18 to the trunnion shaft of the HST 21 is different for each machine, the drive current value at the start of output stored in the adjustment mode and the drive current value near the maximum output can be used to change the speed. The electromagnetic valves 62 and 63 of the trunnion shaft can be controlled so that the HST 21 becomes the set rotational speed at the predetermined shift position of the operation tool 18 and travels at the set travel speed. Further, the driving current value at which the vehicle actually starts traveling can be converted into control data as the driving current value at the start of output, and the actual traveling speed can be accurately controlled.

According to the first and second aspects of the present invention, in a work vehicle in which the HST 21 is shifted by the speed change operation tool 18, it is possible to control the airframe with the same speed sensation without changing the speed change state in the speed change operation tool 18 for each airframe. become able to do.

It is the whole tractor side view. It is the whole tractor top view except a cabin. It is a power transmission block diagram. It is a control block diagram of automatic control. It is a graph showing the relationship between a drive current and HST output-shaft rotation speed. It is a top view of a maximum speed dial. It is a graph showing the relationship between the operation position of a speed change operation tool, and a drive current value.

A tractor 1 will be described below as an example of the work vehicle.
In the present specification, the left and right directions in the forward direction of the work vehicle are referred to as left and right, respectively, the forward direction is referred to as front, and the reverse direction is referred to as rear.

  As shown in FIGS. 1 and 2, the tractor 1 includes front wheels 2, 2 and rear wheels 3, 3 at the front and rear portions of the fuselage, and the rotational power of the engine 5 mounted on the front portion of the fuselage is supplied to the HST 21 in the transmission case 8. The auxiliary transmission 22 is appropriately decelerated and transmitted to the front wheels 2, 2 and the rear wheels 3, 3.

  A steering handle 7 is provided at the handle post 6 in the cabin 4 at the center of the machine body, and a seat 9 is provided behind the steering handle 7. Below the steering handle 7 is provided a forward / reverse lever 10 for switching the advancing direction of the airframe to the front / rear direction. When the forward / reverse lever 10 is rotated forward, the airframe moves forward, and when it is rotated rearward, it moves backward.

  In addition, an accelerator lever 11 for adjusting the engine speed is provided on the opposite side of the forward / reverse lever 10 with the handle post 6 interposed therebetween, and a shift according to the present invention for adjusting the traveling speed is provided at the right corner portion of the step floor 13. An operating tool, that is, an accelerator pedal 18 and left and right brake pedals 19R and 19L for operating the left and right rear wheels 3 and 3 are provided.

A meter panel 16 is provided on the front side of the steering handle 7 at the upper part of the handle post 6 to display the vehicle status such as traveling speed.
Further, the left front side portion of the seat 9 is provided with an auxiliary transmission lever 15 that can select any one of a low speed, a medium speed, a high speed, and a neutral position, and a PTO transmission lever 12 is provided behind the auxiliary transmission lever 15. A maximum speed setting dial 54, a response setting dial 55, and an auto cruise set switch 56 are provided on the right side of the seat 9. The drive current value set by the maximum speed setting dial 54 is determined based on the control data stored in the adjustment mode to be described later. As shown in FIG. 6, 90% is set to the lateral position from 50% to 100% in the rotation range. Set evenly.

A rotary working machine 17 is attached to the rear of the tractor 1.
FIG. 3 is a power transmission block diagram, in which the rotation of the output shaft of the engine 5 is transmitted to the rear wheel drive shaft 27 of the differential case 23 via the damper 20 in the transmission case 8, the HST 21, and the auxiliary transmission unit 22. Drive.

  The rotation of the output shaft of the HST 21 is detected by the HST output shaft sensor 25 as the rotation of the rotation sensor gear 24, and the output shaft rotation of the auxiliary transmission unit 22 is detected by the rear axle rotation sensor 26. Since the HST output shaft sensor 25 and the rear axle rotation sensor 26 calculate the time required to detect the predetermined number of teeth of the sensor gear, the number of rotations at a high speed can be obtained by setting the number of teeth to 1 at low speed and 3 teeth at high speed. It can detect accurately and stop quickly.

  FIG. 4 is a control block diagram of automatic control for controlling the operation of each part of the tractor. The engine ECU 29 for controlling the output of the engine E, the work machine lifting / lowering system ECU 40 for controlling the lifting / lowering of the work machine 17, the front wheels 2, and the rear wheels 3. It is composed of a traveling system ECU 50 that controls the traveling speed by controlling the rotation, and exchanges control signals by CAN communication.

  Input of control data to the engine ECU 29 includes boost pressure from the boost pressure sensor 30, correction signal from the boost pressure correction control switch 36, exhaust temperature from the engine exhaust temperature sensor 31, and engine from the engine rotation sensor 32. The rotation speed of the output shaft, the oil pressure from the engine oil pressure sensor 33, the radiator water temperature from the engine water temperature sensor 34, the fuel pressure on the common rail from the rail pressure sensor 35, and the depression angle of the accelerator pedal 18 of the accelerator sensor 28 The control output from the engine ECU 29 is the rail pressure to the fuel high-pressure pump 37 and the injection signal to the high-pressure injector 38.

The boost pressure correction control switch 36 turns on / off the control for gradually increasing the fuel injection amount when the accelerator lever 11 rotates when the boost pressure is low.
Input of control data to the work implement lifting system ECU 40 includes an operation position signal of the position control lever 41 for raising and lowering the work implement 17, a lift position signal from the lift arm sensor 42, a raising position regulating dial 43 and a lowering speed adjustment. The control output from the work implement elevating system ECU 40, such as an adjustment signal of the dial 44, is an ascending or descending signal to the main raising sol 45 and the main lowering sol 46 of the hydraulic cylinder.

Further, the work implement lifting system ECU 40 communicates with the work implement controller 47 and the communication unit 48 with GPS.
The control data is input to the travel system ECU 50 by the output shaft rotation speed of the HST 21 of the HST output shaft sensor 25, the output shaft rotation speed of the auxiliary transmission unit 22 of the rear axle rotation sensor 26, and the rear wheel 3 of the vehicle speed sensor 53. The rotational speed, the maximum setting speed of the maximum speed setting dial 54, the setting response of the response setting dial 55, the set signal of the auto cruise set switch 56, the operation position of the forward / reverse lever operation position sensor 64 of the forward / reverse lever 10 The operation position of the auxiliary transmission lever operating position sensor 57 of the auxiliary transmission lever 15, the transmission position sensor of the present invention for detecting the depression position of the accelerator pedal 18, that is, the depression signal of the accelerator pedal sensor 58, and the accelerator sensor provided on the accelerator lever 11 59 engine rotation setting signal and oil temperature sensor 60 oil temperature in transmission case 8 The control output from the traveling system ECU 50 includes the brake pedal depression signal from the brake pedal operation detecting sensor 61, the traveling acceleration of the acceleration detecting sensor 52, the engine speed of the engine rotation sensor 66 of the engine 5, and the like. a forward output signal to sol 62, a reverse output signal to HST reverse proportional pressure sol 63, and the like.

The traveling speed, the shift position, the engine water temperature, and other data are displayed on the meter panel 16 and the operation panel 65 provided in front of the steering handle 7.
FIG. 5 shows the relationship between the drive current value applied to the HST forward proportional pressure sol 62 and the HST reverse proportional pressure sol 63 for controlling the hydraulic cylinder that rotates the trunnion shaft of the HST 21 and the HST output shaft rotational speed detected by the HST output shaft sensor 25. The measured drive current value and the measured data of the HST output shaft rotation speed are assumed to fluctuate in the design change line A indicated by the solid line in the design, but the actual measured data is the maximum of the shift width B and the maximum depending on the characteristics of each HST 21 and the aircraft. There is a variation in the rotational speed width C. The drive current value and the measurement data of the HST output shaft rotational speed which are different for each aircraft are stored in the traveling system ECU 50 as control data.

The adjustment mode is performed in a state where the assembly of the tractor 1 is finished and the sub-shift lever 15 is neutral and the driving after the HST 21 is turned off and no traveling load is applied at the final adjustment.
First, in the measurement on the forward side, as the data at the time of acceleration, the drive current is changed from near zero where the HST 21 does not rotate to the maximum drive current value D sufficient to obtain the maximum rotational speed J, and the output shaft rotation of the HST 21 The number of rotations is measured, and the driving start current value F at the start of rotation and the maximum acceleration speed H near the maximum driving current value E of 90% of the maximum driving current D are stored in the traveling system ECU 50 as control data.

  Further, as data at the time of deceleration, the drive current is changed from the maximum drive current value D to near zero, and the maximum deceleration near rotation speed I and the drive stop current value G are stored in the traveling system ECU 50 as control data. The drive stop current value G can be accurately detected by actually running the tractor 1 and measuring it.

Similarly to the above, on the reverse side, the deceleration side control data is stored in the traveling ECU 50.
In addition, since there is a slight time lag when the drive current is applied and the rotation of the HST 21 is output, the rotation speed after a predetermined time has elapsed from the application of the drive current is used as control data.

  The rotation speed of the HST 21 depending on the depression depth of the accelerator pedal 18 uses the speed increase side drive start current value F, the speed increase maximum vicinity speed H, the speed reduction maximum vicinity speed I, and the drive stop current value G. The drive current value calculated from the calculated control change rate is applied to the HST forward proportional pressure sol62 and the HST reverse proportional pressure sol63.

  As shown in FIG. 7, a neutral zone for prohibiting output is provided in the depression start range of the accelerator pedal 18, and the traveling ECU 50 controls to output the drive start current value F at the acceleration start position at the end of the neutral zone. To do. When the accelerator pedal 18 is depressed from the acceleration start position, the drive current value is rapidly increased so that the drive current linearly changes (proportional change) from zero rotation of the HST 21 to the maximum acceleration vicinity H. Further, a maximum output zone is provided at the maximum depression position of the accelerator pedal 18 so that the maximum rotational speed J is output at the maximum drive current value.

  The maximum speed J is determined by the engine speed regulation. However, when the oil temperature sensor 60 detects a predetermined temperature or higher, the maximum drive current value D is set to the maximum speed setting dial 54 and the current value range and near the maximum. By further reducing the regulated drive current value to the lower drive current value E, further increase in the oil temperature is suppressed. The return of the drive current is lower than a predetermined temperature to prevent the occurrence of hunting.

The regulated drive current value is determined by the drive current value calculated from the control change rate.
When the depression of the accelerator pedal 18 is stopped and the driving of the HST 21 is stopped, the driving current for driving forward or backward driving is stopped and a driving current slightly larger than the driving start current value F in the reverse direction after a predetermined time has elapsed. Is applied for a short time (several tens of milliseconds), and the trunnion shaft is returned to the neutral position after returning to the normal position.

  When the accelerator pedal 18 is depressed to a predetermined high speed position or a predetermined high speed position or higher, a change rate of the depression speed is calculated, and according to the change rate, up to a constant change rate that does not overload the engine load, up to the pedal position corresponding speed. Change the speed increase rate. In addition, when the accelerator pedal 18 is stepped on beyond a predetermined high speed position, the speed acceleration rate is decreased when the predetermined speed acceleration rate elapses for a predetermined time, and the speed acceleration rate is canceled when the target speed is reached.

  From the traveling system ECU 50, the set traveling speed is obtained at the depression position of the accelerator pedal 18 using the control data of the maximum vicinity driving current value E, the driving start current value F, and the driving stop current value G detected above. A drive current is output to the HST forward proportional pressure sol62 and the HST reverse proportional pressure sol63 to control the rotation of the trunnion shaft of the HST21.

  When the accelerator pedal 18 is depressed most, not the driving current value based on the control data but the predetermined large driving current value is output to the HST forward proportional pressure sol62 and the HST reverse proportional pressure sol63, so that the highest speed is obtained for each aircraft. Make sure they are not different.

  Further, even if the drive current value (rate) is increased, if the travel speed increase amount (rate) is lower than a predetermined value, the travel load is large, so that the increase in the drive current value is interrupted to prevent an engine stall. Further, when the engine speed reduction is larger than a predetermined rate, the drive current is reduced to prevent engine stall, and when the engine speed is close to the idling speed, the drive current is turned off and the HST 21 is made neutral. After that, when the engine speed returns to the set speed, the engine speed is slowly returned to a predetermined drive current at a predetermined change rate.

  In addition to the control using the measurement data of the drive current value and the HST output shaft rotation speed, the acceleration / deceleration acceleration is set by the response setting dial 55 so that the acceleration of the machine body detected by the acceleration detection sensor 52 becomes the set acceleration. It is also possible to control it. The control using the acceleration is not performed because it takes too much time to detect the acceleration in the low speed state, and the control is performed with the immediately preceding acceleration / deceleration rate.

In addition, since control using this acceleration is difficult to detect a change in acceleration at a low speed, acceleration / deceleration is controlled by a drive current change rate of a separately set change rate line.
The response setting dial 55 controls acceleration / deceleration at a predetermined drive current change rate according to the dial position without performing acceleration control. At the start of deceleration, the speed change after a certain time has elapsed since the current change. Is corrected by the acceleration detected by the acceleration detection sensor 52. The correction at the time of switching in the reverse direction immediately after the forward / reverse switching (forward → reverse or reverse → forward) is performed on the predetermined drive current change rate with the same amount of increase / decrease correction as the correction increase / decrease amount on the deceleration side.

  Further, the rotational speed of the engine 5 is regulated so that the rotational speed detected by the engine rotational sensor 66 does not exceed a predetermined rotational speed, but is slightly higher than that using the restricted rotational speed of the maximum speed setting dial 54. Set to the number of revolutions.

E Nearest maximum drive current value F Drive start current value 18 Shifting operation tool ( accelerator pedal)
21 HST
58 Shift position sensor (accelerator pedal sensor)
50 Control device (traveling ECU)

Claims (2)

The movement of the transmission operating tool (18) is detected by the transmission position sensor (58), the engine speed is adjusted based on the detection value of the transmission position sensor (58), and the trunnion shaft of the HST (21) is rotated. In the shift control device for a work vehicle that achieves the set travel speed, the maximum output that is decreased at a predetermined rate from the maximum output by examining the relationship between the drive current value and the output rotation speed of the HST (21) in the adjustment mode for each aircraft. The relationship between the maximum vicinity drive current value (E) detected as the vicinity detection value and the rotational speed and the drive start current value (F) at the start of output are stored in the control device (50) as control data, and the control data is used. , electromagnetic valve for rotating the trunnion shaft so that the rotational speed of the output shaft of the HST (21) corresponding to the traveling speed set by the speed change operation member (18) (62) controls the driving current value (63) Configuration and , Detection of the maximum near the driving current value (E) the rotational speed and the driving starting current value F at the output start of the maximum output near the detection value at the adjustment mode, and performing separately the forward side and the reverse side Shift control device for work vehicle. The movement of the transmission operating tool (18) is detected by the transmission position sensor (58), the engine speed is adjusted based on the detection value of the transmission position sensor (58), and the trunnion shaft of the HST (21) is rotated. In the shift control device for a work vehicle that achieves the set travel speed, the maximum output that is decreased at a predetermined rate from the maximum output by examining the relationship between the drive current value and the output rotation speed of the HST (21) in the adjustment mode for each aircraft. The relationship between the maximum vicinity drive current value (E) detected as the vicinity detection value and the rotational speed and the drive start current value (F) at the start of output are stored in the control device (50) as control data, and the control data is used. The drive current value of the electromagnetic valves (62) and (63) for rotating the trunnion shaft is controlled so that the output shaft rotational speed of the HST (21) corresponding to the traveling speed set by the transmission operation tool (18) is obtained. Configuration and , The detection of the output at the start of the driving current value, that is stored as the vehicle drive start current value the drive current value when the vehicle is raised to start moving gradually current from a stopped state (F) shift control device for the working vehicle shall be the feature.

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