JP2013007470A - Shift control apparatus of working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a working vehicle run at constant travel speed if an HST pedal takes the same speed change position even if the machine body of the working vehicle differs.SOLUTION: A shift control apparatus of the working vehicle detects the movement of an HST pedal 18 by an HST pedal sensor 58, adjusts the engine speed based on the detected value of the HST pedal sensor 18, and rotates a trunnion shaft of an HST 21 to attain a set travel speed. The apparatus checks a relation between a drive current and output revolution of the HST 21 in an adjustment mode to store it into a control device 50 as control data, changes the drive current by using the control data to attain an output shaft rotation speed set at the detected speed change position of the HST pedal 18, and controls a magnetic valve to rotate the trunnion shaft of the HST 21.

Description

  The present invention relates to a shift control device for a working vehicle, in which a traveling transmission system is provided with an HST transmission mechanism, and the HST transmission mechanism is subjected to shift control by a control unit to adjust the traveling vehicle speed.

  As shown in Patent Document 1, in a working vehicle in which a hydraulic transmission continuously variable transmission (hereinafter referred to as “HST”) continuously shifts forward and backward by trunnion control is provided in a traveling transmission system, the vehicle speed thereof For adjustment, there is known a shift control device for a work vehicle having a control unit that controls an HST transmission mechanism in accordance with an operation position of an HST pedal having a wide range of shift positions.

In this speed change control device, the control unit adjusts the output shaft rotational speed of the HST speed change mechanism by drivingly controlling the trunnion shaft according to the selected position of the HST pedal.
More specifically, means for detecting the rotation position of the HST pedal, means for detecting the rotation position of the forward / reverse switching lever, means for detecting the tilt angle of the movable swash plate of the hydraulic pump, and the tilt angle of the movable swash plate A means for changing is provided, and each means is connected to the controller, and the movable swash plate of the HST speed change mechanism is tilted to the operating direction of the forward / reverse switching lever and the speed set by the main speed change lever.

JP 2002-250437 A

  The shift control device of the work vehicle detects the shift position with a sensor, drives the electromagnetic valve of the actuator with a drive current corresponding to the detected value, and changes the tilt angle of the movable swash plate of the hydraulic pump. However, if the work vehicle is different due to the play of the HST itself or the interlocking mechanism between the actuator and the movable swash plate, the tilt angle of the movable swash plate will not be the same even if the shift position is the same, and the traveling speed will be different.

  Therefore, an object of the present invention is to travel at a constant traveling speed as long as the speed change position 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 HST pedal (18) is detected by the HST pedal sensor (18), the engine speed is adjusted based on the detected value of the HST pedal sensor (18), and the HST (21 ) Of the work vehicle that rotates the trunnion shaft to reach the set travel speed, the relationship between the drive current and the output rotation speed of the HST (21) is checked in the adjustment mode, and the control device ( 50) and using the control data, the drive current is changed so that the output shaft rotational speed is set at the detected shift position of the HST pedal (18), and the trunnion shaft of the HST (21) is rotated. A shift control device for a work vehicle characterized by controlling an electromagnetic valve.

  With this configuration, even if the interlock mechanism of the HST 21 or HST pedal 18 to the HST 21 trunnion shaft is different for each work vehicle, the HST pedal 18 is shifted so as to have a predetermined set traveling speed at a predetermined high-speed rotation position. .

According to a second aspect of the present invention, there is provided the shift control device for a work vehicle according to the first aspect, wherein the adjustment mode is performed in a state in which the driving force transmission after the output shaft of the HST 21 is cut off.
With this configuration, the relationship between the drive current and the HST output shaft rotational speed is converted into control data in a state where there is no travel load fluctuation, and the travel speed can be controlled based on stable control data.

According to a third aspect of the present invention, there is provided the shift control apparatus for a work vehicle according to the first aspect, wherein the feedback control is not performed when the drive current value is lower than a predetermined current value.
With this configuration, the control can be stabilized without causing hunting by not performing the feedback control in a state where the drive current value is low and the traveling speed is difficult to reach the set speed.

  According to the fourth aspect of the present invention, when the HST pedal 18 is set to the fastest position, an electromagnetic valve that rotates the trunnion shaft of the HST 21 with the fastest drive current value set separately is not the control data obtained in the adjustment mode. The shift control device for a work vehicle according to claim 1, wherein the shift control device is configured to control.

With this configuration, the vehicle can be driven at a predetermined maximum speed without being controlled by the control data of the drive current and the HST output shaft rotation speed which are different for each work vehicle.
According to the fifth aspect of the present invention, the shift position of the HST pedal 18 is detected by the HST pedal sensor 58, and the trunnion shaft of the HST 21 is rotated based on the detected value of the HST pedal sensor 58 to reach the set traveling speed. In the shift control device for a work vehicle, the acceleration setting means 55 is provided, and the acceleration detected by the acceleration detection sensor 52 is controlled to be the acceleration set by the acceleration setting means 55. Control device.

  With this configuration, the HST 21 is controlled so as to travel at an acceleration actually measured by the acceleration detection sensor 52, and the acceleration feeling during traveling does not change depending on the work vehicle.

  In the invention according to any one of claims 1 to 5, in a work vehicle that shifts the HST 21 with the HST pedal 18, the shifting state with the HST pedal 18 is not different for each aircraft, so that any aircraft can be operated with the same shifting feeling. become.

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.

An example of a work vehicle will be described below using a tractor as an example.
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. A forward / reverse lever 10 is provided below the left side of the steering handle 7 to switch 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.

  Further, 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 an HST for similarly adjusting the engine speed is provided at the right corner of the step floor 13. The 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 auxiliary transmission lever 15 is configured to be able to select any one of a low speed position, a medium speed position, a high speed position, and a neutral position. A rear PTO transmission lever 12 is provided in the publication of the four-wheel drive lever 14, and a mid PTO transmission lever 12 a is provided on the left side of the rear PTO transmission lever 12. 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.

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 rotation angle of the accelerator lever 11 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.

  Note that the boost pressure correction control switch 36 is configured to detect the rotation of the accelerator lever 11 when the boost pressure is low, and to detect the rotation of the accelerator lever 28 and to gradually increase the fuel injection amount.

  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 ascending so45 and the main descending so 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 operation position sensor 64 of the forward / reverse lever, The operation position of the auxiliary transmission lever operation position sensor 57 of the transmission lever 15, the operation position of the main transmission lever operation position sensor 49 of the main transmission lever 14, the depression signal of the HST pedal sensor 58 of the HST pedal 18, and the oil temperature sensor 60. The oil temperature in the transmission case 8, the brake pedal depression signal of the brake pedal operation detection sensor 61, In traveling such as acceleration in degrees detection sensor 52, the control output from the traveling system ECU50 includes a forward output signal to the HST forward proportional pressure Sol62, a reverse output signals to the HST reverse proportional pressure Sol63.

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 drive current value applied to the HST forward proportional pressure sol62 and the HST reverse proportional pressure sol63 for controlling the hydraulic cylinder that rotates the trunnion shaft of the HST 21 in the adjustment mode, and the HST output shaft rotational speed detected by the HST output shaft sensor 25. Based on the measurement data of the drive current value and the HST output shaft rotation speed measured for the relationship, before the shipment of the tractor 1 after the assembly of the tractor 1, the auxiliary transmission lever 15 is made neutral and the drive after HST21 is turned off so that no traveling load is applied. Done in state. Although the design data changes as indicated by the solid line A, the actual measurement data varies between the speed change width B and the maximum speed width C depending on the characteristics of the HST 21 and each aircraft. The driving 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.

  Then, the driving current is output from the traveling system ECU 50 to the HST forward proportional pressure sol62 and the HST reverse proportional pressure sol63 so that the set travel speed is obtained at a predetermined shift position of the HST pedal 18 using this control data, and the HST21 Controls the rotation of the trunnion shaft.

  In the control using the measurement data of the drive current value and the HST output shaft rotational speed, if the drive current value is lower than the predetermined value, the set travel speed is unlikely to occur, and hunting occurs when feedback control is performed. The feedback control is performed when the value is exceeded.

  Further, when the HST pedal 18 is set to the highest speed, a predetermined drive current is output to the HST forward proportional pressure sol62 and the HST reverse proportional pressure sol63 instead of the measurement data of the drive current value and the HST output shaft rotational speed. , Make sure that the maximum speed does not vary between aircrafts.

  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.

18 HST pedal 21 HST
58 HST pedal sensor 50 Control device (travel ECU)
52 Acceleration detection sensor 55 Acceleration setting means (response setting dial)

Claims (5)

  The movement of the HST pedal (18) is detected by the HST pedal sensor (18), the engine speed is adjusted based on the detected value of the HST pedal sensor (18), and the trunnion shaft of the HST (21) is rotated. In a shift control device for a work vehicle that achieves a set travel speed, the relationship between the drive current and the output rotation speed of the HST (21) is examined in the adjustment mode, and stored as control data in the control device (50). Is used to control the electromagnetic valve that rotates the trunnion shaft of the HST (21) by changing the drive current so that the output shaft rotational speed set at the detection shift position of the HST pedal (18) is used. A shift control device for a working vehicle.   2. The shift control apparatus for a work vehicle according to claim 1, wherein the adjustment mode is performed in a state in which driving force transmission after the output shaft of the HST (21) is cut off.   The shift control device for a work vehicle according to claim 1, wherein feedback control is not performed when the drive current value is lower than a predetermined current value.   When the main speed change lever (14) is set to the fastest position, the electromagnetic valve that rotates the trunnion shaft of the HST (21) is controlled not by the control data obtained in the adjustment mode but by the highest speed drive current value set separately. The shift control apparatus for a work vehicle according to claim 1.   The shift position of the main shift lever (14) is detected by the main shift lever operation position sensor (49), and the trunnion shaft of the HST (21) is rotated based on the detected value of the main shift lever operation position sensor (49). In the shift control device for a work vehicle that achieves the set traveling speed, the acceleration setting means (55) is provided, and the acceleration detected by the acceleration detection sensor (52) is the acceleration set by the acceleration setting means (55). A shift control apparatus for a work vehicle, characterized by being controlled as described above.

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