JP2020018171A - Control device for work vehicle - Google Patents

Abstract

To provide a control device for a work vehicle capable of reducing travel speed of a machine body with preferable following property even to sudden increase of a load on a work device.SOLUTION: A speed reduction ratio setting part 61 sets a speed reduction ratio according to whether or not a load ratio of an engine exceeds a reference value, and a target cam plate position calculation part 62 sets a target cam plate position being a target position of a cam plate of a hydraulic pump 33 so that the travel speed of the machine body is reduced according to the speed reduction ratio from the speed according to the position of a shift lever. A current supplied to proportional pressure reduction control valves 52, 53 of HST is controlled so that the position of the cam plate of the hydraulic pump matches the target cam plate position.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a control device used for a work vehicle such as a combine.

  In the combine, the root of the culm planted in the field is cut by a reaper, the cut culm is transported from the reaper to the threshing device, and the culm is threshed by the threshing device, and the grain is removed. Is collected in the grain tank. The combine is equipped with an engine as a drive source, and the power from the engine is transmitted to working devices such as a reaper and threshing device, and the power from the engine is transmitted to a traveling device composed of a pair of right and left crawlers. Is done.

  Therefore, the load of the engine fluctuates depending on the state of the work in the work machine. When the load on the work implement increases and the load on the engine becomes excessive (overload), the number of revolutions of the engine decreases and the engine may stop. The power transmitted to the traveling device can be shifted by a continuously variable transmission, and the driver's cab is provided with a shift lever operated to adjust the shift by the continuously variable transmission. Therefore, when the load on the engine exceeds a predetermined value, automatic control is performed to reduce the load on the engine by moving the shift lever with a motor to reduce the traveling speed of the body.

JP-A-10-259868

  However, in the configuration in which the traveling speed is reduced via the motor, when the load on the work implement suddenly increases, it is not possible to sufficiently reduce the speed, and there is a possibility that the engine may not be stopped due to a decrease in engine rotation.

  SUMMARY OF THE INVENTION It is an object of the present invention to provide a control device for a work vehicle that can reduce the traveling speed of an airframe with good followability even when the load on the work device suddenly increases.

  In order to achieve the above object, a control device for a work vehicle according to the present invention includes an airframe, an engine, a work device driven by the power of the engine, a swash plate pump and a pump driven by the power of the engine. A continuously variable transmission that includes a motor driven by fluid discharged from the vehicle and outputs power of the motor; a pair of left and right traveling devices that support the body and are driven by the power output from the continuously variable transmission; What is claimed is: 1. A control device for a work vehicle, comprising: an operation member operated to instruct a traveling speed of an airframe by the device, a position detection means for detecting a position of the operation member, and a load corresponding value corresponding to an engine load. A deceleration rate setting means for setting a deceleration rate according to whether or not the speed exceeds a reference value, and a deceleration rate setting means from a speed corresponding to a position where the traveling speed of the aircraft is detected by the position detection means. Target position setting means for setting the target position of the pump swash plate so that the pump is decelerated according to the set deceleration rate, and the position of the pump swash plate coincides with the target position set by the target position setting means. Control means for controlling the continuously variable transmission.

  According to this configuration, the deceleration rate is set according to whether or not the load corresponding value corresponding to the engine load exceeds the reference value, and the traveling speed of the body is changed from the speed corresponding to the position of the operation member to the deceleration rate. The target position of the swash plate of the pump is set so as to be decelerated accordingly. Then, the continuously variable transmission is controlled such that the position of the swash plate of the pump matches the target position. As a result, the responsiveness of the control is higher and the load on the working device is lower than the control in which the operating member is moved by an actuator such as a motor to change the target position of the swash plate of the pump and reduce the traveling speed of the body. The running speed of the aircraft can be reduced with good followability even for a sudden increase in the load of the engine due to a sudden increase.

  The deceleration rate setting means preferably sets a deceleration rate including a proportional term set by multiplying a deviation of the load corresponding value from the reference value by a proportional gain when the load corresponding value exceeds the reference value. As a result, the deceleration rate is set to a larger value as the deviation of the load corresponding value from the reference value is larger, so that the traveling speed of the aircraft can be reduced with better followability to a sudden increase in engine load. Can be.

  The deceleration rate setting means adds, when the load corresponding value exceeds the reference value, an integral term set by multiplying the integral value of the deviation of the load corresponding value from the reference value by an integral gain to the proportional term. A deceleration rate may be set.

  In addition, the deceleration rate setting means removes the proportional term in response to the load corresponding value changing from a value exceeding the reference value to a value less than the reference value, and the position at which the traveling speed of the aircraft is detected by the position detection means. The deceleration rate including the integral term may be set so as to be accelerated toward a speed corresponding to.

  In this case, the deceleration rate setting means, when the proportional term disappears in response to the load corresponding value changing from a value exceeding the reference value to a value less than the reference value, the deceleration rate for the proportional term to be eliminated. Is preferably added to the integral term, and a deceleration rate including the integral term after the addition is set. Thereby, it is possible to suppress a sudden change in the deceleration rate when shifting from a state in which the traveling speed of the aircraft is decelerating to a state in which the traveling speed returns to the normal speed by acceleration. Also, the deceleration rate changes with a slow change in the integral term, and the traveling speed of the aircraft gradually increases (increases) with the change in the deceleration rate. Hunting and the like can be suppressed. Therefore, the ride comfort of the worker can be improved.

  The target position setting means may set the target position from a multiplication value obtained by multiplying a numerical value representing the position detected by the position detection means by a deceleration rate.

  ADVANTAGE OF THE INVENTION According to this invention, the running speed of an airframe can be reduced with favorable followability also to the sudden increase of the load of a working device.

It is a right view which shows the front part of the combine using the control apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows the principal part of the electrical structure of a combine. FIG. 3 is a block diagram showing a specific configuration for HST control. FIG. 5 is a diagram for describing a method of setting a deceleration rate by a deceleration rate setting unit. 5 is a graph showing an example of a change over time of a load factor, a proportional term, an integral term, and a deceleration rate.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Overall structure of combine>
FIG. 1 is a right side view showing a front part of a combine 1 in which a control device according to an embodiment of the present invention is used.

  The combine 1 is a work vehicle that cuts culms and threshes from culms while traveling in a field. The fuselage 11 of the combine 1 is supported by a pair of right and left traveling devices 12. The traveling device 12 employs a crawler having a rough terrain running ability so that the combine 1 can travel in a field.

  The body 11 is provided with a cab 13, a mowing device 14, a threshing device 15, and a grain tank 16.

  The cab 13 is arranged above the front end of the traveling device 12. The cab 13 is provided with a seat 17 on which a worker sits. The cab 13 is provided with an operation panel 18 operated by an operator, for example, from the front to the left of the seat 17.

  The operation panel 18 includes a shift lever 19 and the like. The shift lever 19 is provided, for example, so as to be tiltable in the front-rear direction. The operator can instruct the forward movement of the body 11 by tilting the shift lever 19 forward, and can change the speed of the forward movement based on the amount of tilt. The operator can instruct the body 11 to move backward by tilting the shift lever 19 to the rear side, and change the speed of the reverse movement according to the amount of tilt.

  The reaper 14 is arranged in front of the traveling device 12. The reaper 14 has a weeding tool 21 at the front end thereof, and a cutting blade 22 behind the weeding tool 21. The weeding tool 21 and the cutting blade 22 are supported by a frame 23 before cutting. At the rear end of the pre-cutting frame 23, a cutting horizontal frame 24 extending in the left-right direction is provided. One end of the main cutting frame 25 is connected to the horizontal cutting frame 24. The reaping main frame 25 extends rearward from the reaping horizontal frame 24, and the other end (provided forward and downward, the rear end) is rotatably connected to the frame of the machine body 11. Due to the operation of the cylinder (not shown), the mowing main frame 25 swings, and the swinging movement causes the weeding tool 21 and the cutting blade 22 to rise above the ground, and the weeding tool 21 and the cutting blade 22. Rises and descends to the lowered position where it descends near the ground. When the airframe 11 advances in a state where the weeding tool 21 and the cutting blade 22 are located at the descending position, the seeds of the grain culm planted in the field are separated by the weeding tool 21 and the grain culm is cut by the cutting blade 22. Reaped by

  The threshing device 15 and the grain tank 16 are arranged side by side at a position above the traveling device 12 and behind the reaper 14. The cut culm is conveyed to the threshing device 15 by the cutting device 14. The threshing device 15 conveys the stem side of the grain stalk backward by a threshing feed chain, and supplies the spike end side of the grain stalk to a handling room to thresh. Then, the grains are transported from the threshing device 15 to the grain tank 16, and the grains are stored in the grain tank 16. A grain discharge auger 26 is connected to the grain tank 16, and the grains stored in the grain tank 16 can be discharged outside the machine by the grain discharge auger 26.

<Electrical configuration of combine>
FIG. 2 is a block diagram showing a main part of an electrical configuration of the combine 1.

  The combine 1 is equipped with an engine 31 and an HST (Hydro Static Transmission: hydrostatic transmission) 32. The HST 32 shifts and outputs the power of the engine 31. Specifically, the HST 32 includes a hydraulic pump 33 driven by the power of the engine 31 and a hydraulic motor 34 driven by the fluid discharged from the hydraulic pump 33. The hydraulic pump 33 is a variable displacement swash plate type piston pump. In a range where the inclination angle of the pump swash plate with respect to the axis of the pump rotation shaft of the hydraulic pump 33 is less than 90 °, the larger the inclination angle is, the smaller the discharge amount of the hydraulic oil from the hydraulic pump 33 becomes. When the inclination angle of the pump swash plate is 90 °, the discharge of the hydraulic oil from the hydraulic pump 33 stops. Further, when the inclination angle of the pump swash plate exceeds 90 °, the discharge direction of the hydraulic oil from the hydraulic pump 33 is reversed when the inclination angle is less than 90 °. The hydraulic motor 34 is a variable displacement swash plate type piston motor. When the inclination angle of the motor swash plate with respect to the axis of the motor rotation shaft of the hydraulic motor 34 is constant, the larger the amount of hydraulic oil supplied to the hydraulic motor 34, that is, the larger the amount of hydraulic oil discharged from the hydraulic pump 33, The rotation speed of the motor rotation shaft increases.

  The power of the engine 31 is shifted by the HST 32 and transmitted to the left and right traveling devices 12 and the reaper 14. In addition, the power of the engine 31 is transmitted to the threshing device 15 without being subjected to the shift operation by the HST 32. A power transmission mechanism (not shown) including a clutch and the like is interposed between the HST 32 and the traveling device 12, between the HST 32 and the reaper 14, and between the engine 31 and the threshing device 15, respectively.

  The combine 1 is equipped with a single main ECU (Electronic Control Unit) 41 for overall overall control and a plurality of ECUs for specific individual control. ECUs for individual specific control include, for example, engine ECU 42 and HSTECU 43. The main ECU 41, the engine ECU 42, and the HST ECU 43 are each configured to include a micro controller unit (MCU: Micro Controller Unit).

  The main ECU 41 is communicably connected to each ECU for specific control, that is, the engine ECU 42 and the HSTECU 43. The main ECU 41 receives information obtained by each ECU for individual specific control from detection signals of various sensors and the like, and transmits commands and information required by each ECU for control to each ECU.

  The engine ECU 42 receives an instruction from the main ECU 41 and controls the engine 31.

  A shift lever position sensor 44 that outputs a detection signal corresponding to the operation position of the shift lever 19 is connected to the HSTECU 43, and the detection signal of the shift lever position sensor 44 is input. Further, the HST ECU 43 is connected to a pump swash plate position sensor 45 that outputs a detection signal according to the position of the pump swash plate (the inclination angle from the reference position) of the hydraulic pump 33 of the HST 32. The detection signal of the position sensor 45 is input. The HST ECU 43 receives a command from the main ECU 41 and controls the HST 32 (HST control) based on information obtained from each detection signal of the shift lever position sensor 44 and the pump swash plate position sensor 45.

<Specific configuration for HST control>
FIG. 3 is a block diagram showing a specific configuration for HST control.

  The HST 32 is provided with an electronically controlled servo cylinder 51 for changing the inclination angle of the pump swash plate of the hydraulic pump 33. The servo cylinder 51 has a first pressure chamber to which hydraulic pressure is supplied from a forward-side proportional pressure reduction control valve 52 and a second pressure chamber to which hydraulic pressure is supplied from a reverse-side proportional pressure reduction control valve 53. Further, the servo cylinder 51 has a rod that moves linearly due to the pressure difference between the first pressure chamber and the second pressure chamber, and the linear movement of the rod changes the inclination angle of the pump swash plate. The servo cylinder 51, the forward-side proportional pressure-reducing control valve 52, and the reverse-side proportional pressure-reducing control valve 53 constitute a servo mechanism 54 that controls the inclination angle of the pump swash plate of the hydraulic pump 33.

  The HST ECU 43 includes a deceleration rate setting unit 61, a target swash plate position calculation unit 62, an actual swash plate position detection unit 63, a deviation calculation unit 64, and a PI (Proportional-Integral) calculation unit as processing units for HST control. 65 are substantially provided. Each processing unit is realized by software by program processing or by hardware such as a logic circuit.

  FIG. 4 is a diagram for explaining a method of setting the deceleration rate by the deceleration rate setting unit 61. FIG. 5 is a graph showing an example of a change over time of the load factor, the proportional term, the integral term, and the deceleration rate.

  The deceleration rate setting unit 61 sets a deceleration rate according to the load of the engine 31.

  Specifically, information on the rotation speed of the engine 31 (hereinafter, referred to as “engine rotation speed”) is input from the engine ECU 42 via the main ECU 41 to the HST ECU 43. The combine 1 is provided with an engine rotation sensor that outputs a pulse signal synchronized with the rotation of the engine 31 (the rotation of the crankshaft) as a detection signal, and the engine speed is obtained from the detection signal of the engine rotation sensor. .

  The deceleration rate setting unit 61 uses the rotation speed of the engine 31 in a no-load state as a reference rotation speed, obtains a reduction amount of the engine rotation speed from the reference rotation speed, and determines a ratio of the reduction amount to a predetermined reference reduction amount. As a load factor (%). Then, the deceleration rate setting unit 61 sets a deceleration rate according to whether or not a load rate as a load corresponding value corresponding to the load of the engine 31 exceeds a reference value. More specifically, when the load factor exceeds the reference value of 100% (time T1, T3), the deceleration rate setting unit 61 sets a proportional term and an integral term in order to reduce the traveling speed of the body 11. , The sum of the proportional and integral terms is added to 1000 (‰) to set the deceleration rate. The proportional term is set by multiplying the deviation of the load factor from the reference value by a proportional gain. The integral term is set by multiplying the integral value of the deviation of the load factor from the reference value by the integral gain.

  Referring to FIG. 3, target swash plate position calculating section 62 sets a detection value obtained by digitizing a detection signal of shift lever position sensor 44 to a value corresponding to the position of shift lever 19, and sets the detected value to a deceleration rate. From the multiplication value obtained by multiplying the deceleration rate set by the setting unit 61, a value according to a target swash plate position, which is a target of the position of the pump swash plate of the hydraulic pump 33, is calculated according to a predetermined calculation formula. It should be noted that a map defining a relationship between a multiplied value obtained by multiplying the detected value of the shift lever position sensor 44 by the deceleration rate and a value corresponding to the target swash plate position is stored in the memory of the HSTECU 43, The calculation unit 62 may set a value according to the target swash plate position from the multiplied value according to the map.

  The actual swash plate position detector 63 converts a detection value obtained by digitizing the detection signal of the pump swash plate position sensor 45 into an actual position (inclination angle) of the pump swash plate of the hydraulic pump 33 according to the actual swash plate position. Value.

  The deviation calculator 64 subtracts a value corresponding to the actual swash plate position calculated by the actual swash plate position detector 63 from a value corresponding to the target swash plate position calculated by the target swash plate position calculator 62. The swash plate position deviation, which is the deviation of the target swash plate position from the actual swash plate position, is calculated.

  The PI calculation unit 65 performs a PI (proportional integration) calculation using the swash plate position deviation, and sets a target current value as a target of the current value supplied to each of the proportional pressure reduction control valves 52 and 53 from the result of the PI calculation. I do.

  Then, in the HST ECU 43, the current supplied to the proportional pressure reducing control valves 52, 53 is adjusted according to the respective target current values so that the value of the current supplied to the proportional pressure reducing control valves 52, 53 matches the target current value. Is controlled by the chopper at the selected duty.

  By setting a deceleration rate of less than 1000 (‰), a value corresponding to the target swash plate position of the hydraulic pump 33 is set to a smaller value than when the deceleration rate is set to 1000 (‰). You. As a result, the amount of hydraulic oil discharged from the hydraulic pump 33 decreases, the rotation speed of the hydraulic motor 34 transmitted to the traveling device 12 decreases, and the traveling speed of the machine body 11 decreases. The load on the engine 31 is reduced by reducing the traveling speed of the body 11. Then, as shown in FIG. 5, when the load factor of the engine 31 decreases from a value exceeding the reference value of 100% to a value equal to or less than the reference value (time T2, T4), the deceleration rate setting unit 61 sets As shown in FIG. 4, the proportional term previously set is eliminated, the integral term is set, and the integral term is added to 1000 (‰) in order to increase the traveling speed of No. 11. , Set the deceleration rate. At this time, the deceleration rate setting unit 61 sets the integral gain so that the deceleration rate of the proportional term to be eliminated is added to the integral term, and multiplies the integral gain by the integral value of the deviation from the reference value of the load factor. This sets the integral term. This suppresses a sudden change in the deceleration rate when the traveling speed of the body 11 switches from deceleration to acceleration.

<Effects>
As described above, the deceleration rate according to whether the load factor of the engine 31 exceeds the reference value is set, and the traveling speed of the body 11 is reduced from the speed corresponding to the position of the shift lever 19 according to the deceleration rate. Thus, the target swash plate position which is the target position of the swash plate of the hydraulic pump 33 is set. Then, the HST 32 is controlled such that the position of the swash plate of the hydraulic pump 33 matches the target swash plate position. As a result, the responsiveness of the control is higher than the control in which the shift lever 19 is moved by an actuator such as a motor to change the target position of the swash plate of the hydraulic pump 33 and the traveling speed of the body 11 is reduced. The traveling speed of the machine body 11 can be reduced with good followability even when the load on the engine 31 is suddenly increased due to a sudden increase in the load on the working device such as the device 14 and the threshing device 15.

  When the load factor of the engine 31 exceeds the reference value, a deceleration rate including a proportional term set by multiplying a deviation of the load factor from the reference value by a proportional gain is set. As a result, the deceleration rate is set to a larger value as the deviation of the load rate from the reference value is larger, so that the traveling speed of the body 11 is reduced with better followability to a sudden increase in the load of the engine 31. be able to.

  In response to the load factor of the engine 31 changing from a value exceeding the reference value to a value less than the reference value, the proportional term disappears, and the deceleration rate of the disappeared proportional term is added to the integral term, A deceleration rate including the integral term after the addition is set. Thereby, it is possible to suppress a sudden change in the deceleration rate when shifting from a state in which the traveling speed of the body 11 is decelerating to a state in which the traveling speed returns to the normal speed by acceleration. Further, since the integral term slowly changes with the change in the load factor, the deceleration rate changes with the slow change of the integral term, and the traveling speed of the airframe 11 gradually decreases with the change of the deceleration rate. Accelerate (increase). Therefore, it is possible to suppress a sudden increase in the traveling speed of the body 11 or hunting. Therefore, the ride comfort of the worker can be improved.

<Modification>
The embodiments of the present invention have been described above, but the present invention can be embodied in other forms.

  For example, when the load factor exceeds the reference value of 100%, deceleration rate setting section 61 sets a proportional term and an integral term, and decelerates by adding the sum of the proportional term and the integral term to 1000 (‰). Although the rate is set, the differential term is further set by multiplying the differential value of the load factor by the differential gain, and the deceleration rate is set by adding the sum of the proportional term, the integral term and the differential term to 1000 (‰). May be.

  Also, combine 1 is taken up as an example of a work vehicle, but the present invention is not limited to combine 1 and is applied to work vehicles other than combine 1 such as a harvester for harvesting vegetables such as ginseng, radish, green soybeans, and cabbage. can do.

  In addition, various design changes can be made to the above-described configuration within the scope of the matters described in the claims.

1: Combine 11: Airframe 12: Traveling device 14: Harvesting device (working device)
15: Threshing device (working device)
19: Shift lever (operation member)
31: Engine 32: HST (Continuously variable transmission)
33: Hydraulic pump 34: Hydraulic motor 41: Main ECU
42: Engine ECU
43: HST ECU (control device, position detecting means, deceleration rate setting means, target position setting means, control means)
44: shift lever position sensor (position detecting means)
61: deceleration rate setting section (deceleration rate setting means)
62: Target swash plate position calculation unit (target position setting means)

Claims (6)

A machine body, an engine, a working device driven by the power of the engine, a swash plate type pump driven by the power of the engine, and a motor driven by a fluid discharged from the pump; A continuously variable transmission that outputs the vehicle, a pair of left and right traveling devices that support the body and are driven by the power output from the continuously variable transmission, and operate to indicate a traveling speed of the aircraft by the traveling device. Control device for a working vehicle, comprising:
Position detection means for detecting the position of the operation member,
Deceleration rate setting means for setting a deceleration rate according to whether a load corresponding value corresponding to the engine load exceeds a reference value,
The target position of the swash plate of the pump is set such that the traveling speed of the body is reduced according to the deceleration rate set by the deceleration rate setting means from a speed corresponding to a position detected by the position detection means. Target position setting means to be set;
Control means for controlling the continuously variable transmission so that the position of the swash plate of the pump coincides with the target position set by the target position setting means.   When the load corresponding value exceeds the reference value, the deceleration rate setting means sets the deceleration rate including a proportional term set by multiplying a deviation of the load corresponding value from the reference value by a proportional gain. The control device according to claim 1, wherein the setting is performed.   When the load corresponding value exceeds the reference value, the deceleration rate setting means sets the proportional term by multiplying an integral value of a deviation of the load corresponding value from the reference value by an integral gain. The control device according to claim 2, wherein the deceleration rate is set by adding an integral term.   The deceleration rate setting means causes the proportional term to disappear according to a change in the load corresponding value from a value exceeding the reference value to a value equal to or less than the reference value, and the traveling speed of the body is changed to the position detection means. 4. The control device according to claim 3, wherein the control unit sets the deceleration rate including the integral term so as to accelerate toward a speed corresponding to a position detected by the control unit.   The deceleration rate setting means, when the load corresponding value has changed from a value exceeding the reference value to a value equal to or less than the reference value, when the proportional term disappears, The control device according to claim 4, wherein a deceleration rate is added to the integral term, and the deceleration rate including the integrated term after the addition is set.   6. The target position setting unit according to claim 1, wherein the target position setting unit sets the target position from a multiplication value obtained by multiplying a numerical value representing a position detected by the position detection unit by the deceleration rate. 7. Control device.

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