JP2003226165A - Speed change operation device for working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem on a tractor having a throttle lever and a hydromechanical transmission (HMT) which can maintain stable speed and loading work during low speed working travel that engine stop occurs due to lack of the revolving output of an engine or the need for troublesome work exists in resetting the throttle lever to a high revolution side when a speed change pedal is actuated for high speed operation. <P>SOLUTION: The output speed of the HMT is varied by the actuation of the speed change pedal 5. A thrust accelerating operation part 6 is provided on the lower face of the speed change pedal 5 for increasing/reducing the output speed of the engine set and held by the throttle lever 4 at the same time when the pedal is actuated. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift operation device for a working vehicle having a hydraulic mechanical continuously variable transmission, such as a tractor or a lawn mower. 2. Description of the Related Art Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 5-215200, a hydraulic mechanical type continuously variable transmission (hereinafter, HMT) comprising a hydrostatic continuously variable transmission section and a gear mechanism section has been known. It is known that this HMT is mounted on a construction vehicle or a cargo handling vehicle. [0003] However, in the work vehicle capable of maintaining the output rotation speed of the engine as described above, the vehicle speed and load work can be maintained at a low speed while the work is being performed. When the vehicle speed is increased by depressing the pedal, the output becomes insufficient and engine stall occurs, or the trouble of resetting the throttle lever to the high rotation side is required. [0004] In view of the above-mentioned problems, the present invention provides a shift control device for a working vehicle as follows. That is, a hydromechanical continuously variable transmission (1) including a hydrostatic continuously variable transmission section (1a) and a gear mechanism section (1b) for transmitting the rotational power of the engine (E), and a gear having a plurality of gear positions. In a working vehicle transmitting to the driving wheels (2F, 2R) via a transmission (9), the working vehicle includes a throttle lever (4) for setting and maintaining an output rotation speed of the engine (E); A shift pedal (5) for shifting the output rotation speed of the continuously variable transmission (1) is provided, and the engine () set and held by the throttle lever (4) simultaneously with the depression operation of the shift pedal (5). E) A shift operation device for a work vehicle, comprising an accelerator operation section (6) capable of increasing and decreasing the output rotation speed. (Operation) In the shift control device for a work vehicle configured as described above, when the shift pedal (5) is depressed, the vehicle speed is increased, and at the same time, the throttle of the engine (E) is also increased. As a result, even when the speed is increased in the working state, the work load does not increase and engine stall does not occur, and when the work is completed and the vehicle is moved on a general road at high speed. This eliminates the need to perform the speed change operation and the throttle operation separately, thereby improving the operability of the vehicle. An embodiment of the present invention will be described below with reference to an agricultural tractor T as a working vehicle. First, the configuration of the tractor T will be described. As shown in FIG. 2, the tractor T has a diesel engine E inside a bonnet 11 and a front axle case for supporting left and right front wheels 2F, 2F below the engine E. A transmission case 12 containing a hydraulic mechanical continuously variable transmission (hereinafter referred to as HMT1) or the like is connected, and a rear axle case 13 supporting the rear wheels 2R, 2R is connected to the left and right rear portions of the case 12. . A cabin 14 is formed above the transmission case 12 at the rear of the hood 11 so as to cover the periphery of the cockpit 15. The structure inside the cabin 14 will be described.
As shown in the figure, a shift lever 3 for setting the shift position of the auxiliary transmission 9 is provided.
Is provided, and a neutral position detection switch 17 that is turned on when the lever 3 is operated to the neutral position is provided. The shift lever 3 is a lever guide 1 shown in FIG.
As shown in FIG. 6, the so-called h-shaped shift mode is configured, and more specifically, once from a linear low-speed operation area (F1, R) assuming forward and backward movement during work and a neutral position (N) in the low-speed operation area. A high-speed forward operation area (F) operated outward from the vehicle body and operated forward from the neutral position (N)
2). A lever 18 for projecting and lowering the work implement is provided inward of the speed change lever 3, and a lever position sensor 18s for detecting an operation position is provided at the base of the lever 18. A PTO shaft 2 at the rear of the vehicle body is provided beside the cockpit 15.
An independent PTO on / off switch 23 for turning on / off the rotation of the front wheel 2F, increasing the speed of the front wheel 2F during braking, applying a brake to the rear wheel 2R on the inside of the rotation, and further raising the work implement R to the non-working position. Various setting devices such as a turning control switch 24 for turning on and off the operation of so-called turning control are provided. Then, the sensors 18s...
Are connected to the controllers 10a, 10b,..., Which are the control means 10 below the cockpit 15. Further, a meter panel 25 having various notification devices such as a pilot lamp, a liquid crystal monitor, and an alarm buzzer is provided in front of the cockpit 15, and a handle post 27 having a steering handle 26 protruding behind the meter panel 25 is provided. A steering wheel angle sensor 26 s is provided inside 27 as a means for detecting a turning operation of the vehicle body. On one side surface of the handle post 27, there is provided a throttle lever 4 or the like which is provided with a friction material on a rotation support portion and sets and holds the output rotation speed of the engine E, and pushes and pulls the lever 4 back and forth. Operate the wire 28a
The throttle of the engine E, that is, the output rotation speed is increased / decreased through a mechanical interlocking mechanism such as a link member or a link member. On the floor 29 in front of the cockpit 15, a clutch pedal 30, a shift pedal 5, which is a shift operation device of the present invention, left and right brake pedals 31, which respectively brake the left and right rear wheels 2R, 2R, 31 etc. are provided. As shown in FIG. 1, the speed change pedal 5 is supported on a horizontal shaft 33 on a plate member 32 attached to the opening of the floor 29. The output rotation of the HMT 1 is constantly attached to the rotation base toward the deceleration side. In addition to a spring and a damper mechanism for energizing the pedal, an arm portion 5a extending downward is provided on the side of the pedal, and the rotation of the arm portion 5a is provided below the floor 29. The position is transmitted to the position sensor 5s) to detect the depression amount of the pedal 5. Further, below the speed change pedal 5,
When the pedal 5 is depressed by a predetermined value or more, an accelerator operating portion 6 is provided which comes into contact with the lower surface of the pedal and is pushed down the floor, and a lower end of the pressing type accelerator operating portion 6 is turned around a horizontal axis 34 by a mechanical interlocking mechanism. The engine E is connected to a throttle adjustment section of the engine E via a wire 35 and a wire 28b. As a result, the speed can be increased only when the accelerator operation section 6 is depressed with the throttle position set and held by the throttle lever 4, that is, the engine speed as a base point. To explain the rear part of the vehicle body of the tractor T, a rear part of the transmission case 12 is provided with a cylinder case 36 in which a hydraulic cylinder for lifting and lowering the work machine is provided. It is configured to rotate up and down. On one side of the lift arm 37, a lift arm angle sensor 37s is provided at the rotation base. Thus, in the working machine controller 10b, which will be described later, the solenoid 35a of the working machine lifting proportional flow control valve or the working machine lifting proportional flow rate control valve is adjusted so that the operating angle of the working machine raising / lowering lever 18 and the set angle of the lift arm 37 match. A control (position control) for raising and lowering the work implement R by supplying current to the solenoid 35b of the work implement lowering proportional flow control valve is provided. A three-point link mechanism 38 comprising a top link and left and right lower links is provided at the rear of the vehicle body, and various working machines such as a ground work machine are connected to the link mechanism 38. In FIG. 2, a rotary working machine R is connected, and the rotary working machine R is configured to input the rotation of the PTO shaft 22 via a universal joint and drive the rotary claw 39 to rotate. ing. Next, the power transmission structure of the tractor T will be described with reference to FIG. The rotational power of the engine E is
It is taken out from the engine output shaft 40 and transmitted to the first shaft 41 supported at the front part in the transmission case 12 via the main clutch Cm. The first shaft 41 has a PTO on the power upper side.
A PTO power branching gear 42 is provided as a branch of the system power, and the rear end of the coaxial 41 is connected to the pump input shaft 4 of the HMT 1.
3 is connected. The HMT1 is
This is a main transmission for traveling system power comprising a hydrostatic stepless transmission section (hereinafter, HST1a) and a planetary gear type transmission mechanism section 1b. The swash plate tilt angle in the pump P of the HST section, that is, the trunnion shaft 7 , The output rotation speed of the motor M is continuously changed from forward rotation to reverse rotation. The trunnion shaft 7 is provided with a potentiometer type sensor (hereinafter referred to as a trunnion shaft angle sensor 7s) for detecting a coaxial angle, and an electric motor 8 as a trunnion shaft operation actuator. The rotation of the trunnion shaft 7 is appropriately changed by driving the motor 8 in accordance with the above. Here, the shift lever 3 of the HMT 1 is used.
And the trunnion shaft 7 are electrically interlocked, but the two members 3 and 7 may be mechanically interlocked and connected by a link mechanism, a cam mechanism, or a wire or the like. Further, the pump input shaft 43 protrudes further rearward from the HST section main body, and a planetary gear mechanism 1b described later.
Are connected. The power transmission path of the traveling system is an HST
A second shaft 45 is disposed behind the pump input shaft 43 of FIG. 1a, and the second shaft 45 has an HM for measuring the number of revolutions output from the planetary gear mechanism 1b and the gear mechanism 1b in order from the front.
A T output rotation detecting gear 46, a first clutch mechanism (hereinafter, referred to as a first clutch mechanism) for turning on / off the power transmission output from the gear mechanism unit 1b.
An HMT clutch C1), a first input gear 48 for taking in rotation of a motor output shaft 47 of the HST1a described later,
Further, a gear-type auxiliary transmission 9 is provided behind the input gear 48. The planetary gear mechanism 1b includes a plurality of planetary gears 50, an internal gear 51 which meshes with the outer peripheral edge of the planetary gears 50 and rotates integrally with the second shaft 45, and the second shaft 45. The sun gear 52 and the like meshing with the inner peripheral edge of the planetary gear 50 are rotated upward, and the planetary gears 50 are supported by a carrier 44 and connected integrally with the pump input shaft 43. . The sun gear 52 is configured to idle on the second shaft 45, and the rear portion is configured to rotate integrally with the second input gear 53. In the power transmission path on the motor M side of the HST 1a, a second output gear 54 meshing with the second input gear 53 is provided at an intermediate portion of a motor output shaft 47, and a second clutch mechanism (hereinafter, HST clutch) is provided. The first output gear 55 meshes with the first input gear 48 via a counter gear via C2). The HMT clutch C1 and the HST
The clutch C2 is configured so as to be hydraulically pressed by an energization command of a traveling controller 10a described later.
As a result, the rotational power of the engine E is transmitted to the auxiliary transmission 9.
In order to transmit to the
The rotation of the carrier 44 is combined with the rotation of the sun gear 52 that rotates integrally with the motor output shaft 47 by setting the T clutch C2 to “disengage” to drive the second shaft 45 (HMT mode) or the HMT clutch C1. "Off" and HST
Only the rotation of the motor output shaft 47 is transmitted to the auxiliary transmission 9 via the engagement of the first input / output gears 55 and 48 with the clutch C2 being "on" (HST mode). I have. The rotation obtained from the HMT mode is detected by an HMT rotation detection sensor 46s provided in proximity to the output rotation detecting gear 46 of the HMT 1, and the rotation obtained from the HST mode is detected by the second output. Gear 5
The vehicle speed in each mode is detected indirectly by the detection by the HST rotation detection sensor 54 s provided in the vicinity of the HST rotation sensor 4. The sub-transmission 9 is a gear-type transmission having two high-speed (F2) and low (F1) shift positions and a reverse (R) position operated by the shift lever 3. The rotational power decelerated at the same shift position is transmitted to the left and right rear wheel drive shafts 56 and the rear wheels 2 via the rear wheel differential mechanism 55.
In addition to the transmission to the front wheel 2F via the front wheel speed increasing device 58 and the front wheel differential mechanism, the transmission to the front wheel 2F is performed by the front wheel power split gear 57 provided on the power upper side than the rear wheel differential mechanism 55. A disk-type brake mechanism 60 is provided on the left and right rear wheel drive shafts 56 to rotate the coaxial 56, that is, to operate the rear wheel 2R to extend and retract the piston of a brake hydraulic cylinder 61L (61R) acting as a brake actuator. The left and right sides or the left and right sides are braked integrally. On the other hand, in the transmission path of the PTO-system power, a driven gear 65 meshing with the PTO-system power branch gear 42 is provided at a front portion in the transmission case 12, and a third gear for supporting the driven gear 65 is provided. A clutch mechanism (hereinafter, PTO clutch C3) for turning on / off the transmission power is provided on the lower side of the power of the shaft 66. In addition, the PTO
The clutch C3 is configured to perform an on / off operation by hydraulic pressure according to an energization command of a controller 10b described later.
The PTO clutch C3 is provided with a PTO
A transmission 67 is provided to change the rotational speed of the PTO shaft 22 in several steps. Next, a control system of the tractor T will be described with reference to FIG. The control means 10 of the tractor T includes a traveling controller 10a that processes control related to shifting,
A work machine controller 10b for processing the control of the work machine R, a meter panel controller 10c for processing the display device such as the liquid crystal monitor, and the like. Each controller is a CP for processing various signals.
U, a RAM for temporarily storing these signal information, and a storage means such as an EEPROM for storing various control programs. Further, each controller 10a, 10
Each of b and 10C is connected by a communication line, and is configured to be able to transmit and receive each other's sensor information and output information. The traveling controller 10a receives the input of the transmission pedal position sensor 5s, the neutral position detection switch 17, the trunnion shaft angle sensor 7s,
The steering angle sensor 26s, the HMT rotation sensor 46s, the HST rotation detection sensor 54s, and the like are connected and provided. The output unit includes an electric motor 8 for forcibly changing the rotational position of the trunnion shaft 7 and an HMT clutch C.
Solenoid 70, H
Actuates the solenoid 71 of the proportional flow control valve for pressing the ST clutch C2, the solenoids 72, 72 of the proportional flow control valve for operating the hydraulic cylinders 61L, 61R for braking the left and right rear wheels 2R, 2R, and the front wheel speed increasing device 58. The solenoid 73 of the switching control valve to be operated is connected and provided. Further, the controller 10b for lifting and lowering the working machine
The input unit is connected to the turning control switch 24, the lever position sensor 18s at the base of the work equipment elevating lever 18, the lift arm angle sensor 37s, the independent PTO on / off switch 23, and the like. Ascending and descending solenoids 74a, 74b of a proportional flow control valve for sending pressure oil to the working machine elevating cylinder, a PTO clutch C3
And a solenoid 75 of a switching control valve for connecting and disconnecting the valve. The output of the liquid crystal monitor, the pilot lamp,
An alarm buzzer or the like is connected. In the tractor T configured as described above, when the power is turned on and the engine E is started, each of the controllers 10a, 10b... First performs a sensor check process of various sensors and setting devices as shown in FIGS. After that, various controls are executed. The flowchart shown in FIG. 7 shows the outline of the control executed by the traveling controller 10a. In the controller 10a, various setting devices and switches are read in STEP1, and a sensor check is performed only when the engine is started in STEP2. Perform Thereafter, in STEP3, a process of shifting control by operating the shift lever 3 and the shift pedal 5 is performed, and in STEP4, turning control is performed, and the process returns. Here, the processing of the steering wheel angle sensor 20s in the sensor check in STEP 2 will be described with reference to FIG. In the sensor check process of the steering wheel angle sensor 20s, first, in STEP1, the power supply to the electric motor 8 is suppressed, and the vehicle is set in a state in which the vehicle cannot travel. Then, in STEP 2, the liquid crystal monitor of the meter panel 25 is
A guidance display is provided to operate the steering handle 20 from one of the left and right lock positions to the other lock position. When the operator operates the steering wheel according to the guidance display, the detected value and the E
The internal storage value stored in the EPROM is compared with the internal storage value. If the difference is equal to or greater than a predetermined value, information is transmitted to the meter panel controller 10c in STEP6, an alarm buzzer is activated for a predetermined time, and the operation proceeds to STEP7. In this way, the operation of the turning control is restrained, and the fact that the vehicle is in the restraint state is displayed. Then, in STEP 8, the energized braking state of the electric motor 8 is released, and the tractor T is set in a running state. As a result, even if the operation is started while the sensor 20s is out of order and the steering wheel 20 is operated left and right, the turning control is not easily activated, or conversely, the steering wheel 20 is operated.
It is no longer possible to operate in a state that is not suitable for turning control, such as when the steering wheel is operated only by slightly steering. Further, here, the configuration is such that the sensor 20s is checked by a predetermined steering operation performed by the operator at the time of starting the engine, so that a failure state can be easily found at an early stage. In this case, after the failure of the sensor 20s is detected, the operator is notified by a monitor or an alarm buzzer. However, the tractor is stopped by continuing the check in STEP 1 or stopping the engine E. A configuration in which the vehicle cannot be driven may be adopted. The flowchart shown in FIG.
The shift control process in STEP3 is shown. In STEP1, it is determined whether the neutral position detection switch 17 of the shift lever 3 is ON, and if this is YES,
In STEP2, the clutches C1 and C2 are set to the HST mode, and the electric motor 8 sets and holds the trunnion shaft 10 at a position where the detection value of the rotation sensor 54s becomes zero. As a result, the speed can be quickly changed at the time of starting. On the other hand, if the determination in STEP 1 is NO, it is determined in STEP 3 whether the depressing operation of the shift pedal 5 is performed, and if the determination is YES, STEP 4
To the trunnion shaft 7 according to the amount of depression of the pedal 5.
Change the angle of. The graph shown in FIG. 11 shows the relationship between the engine speed and the vehicle speed at the standard time (when no load is applied). For example, when the sub-shift is set to “low” and the shift pedal 5 is depressed at the point P, L1 As shown by the dotted line in
At the initial stage of the depression, the vehicle speed is slightly increased, and then increased with the engine speed. Here, the HMT,
The vehicle speed is detected by the HST rotation sensors 46s and 54s,
The vehicle travels in the HMT mode up to a predetermined vehicle speed S1, and travels in the HST mode when the vehicle speed exceeds the vehicle speed S1. When the shift pedal 5 is depressed by a predetermined amount or more, the accelerator operation section 6 is simultaneously pressed as described above, and the throttle of the engine E is also increased.
In this way, the shift operation and the accelerator operation are separately performed when temporarily moving at a high speed during the work, particularly when turning or changing the work location, or when the work is completed and the general road is moved at a high speed. This eliminates the need and improves the operability of the tractor T. Further, here, a gap is provided between the lower surface of the shift pedal 5 and the accelerator operation section 6, and the throttle is accelerated when the shift pedal 5 is depressed by a predetermined amount or more. In comparison, the operability is better when the vehicle speed is finely adjusted. As another form of the transmission lever 3,
As shown in FIG. 12, the accelerator operation unit 6 is
The speed change pedal 5 and the throttle pedal 6 ′ are provided side by side on the floor 29, and the throttle pedal 6 ′ is depressed at the same time as the shift pedal 5 is depressed. The number may be increased. As a result, it is possible to select whether or not to increase the throttle according to the judgment of the operator, as compared with a configuration in which the accelerator operation section 6 is provided below the speed change pedal 5.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a speed change pedal. FIG. 2 is an overall side view of the tractor. FIG. 3 is a diagram showing the periphery of a speed change lever. FIG. 4 is a view showing the periphery of a handle. FIG. 5 is a diagram showing a transmission mechanism of the tractor. FIG. 6 is a diagram showing a connection state of a control unit. FIG. 7 is a flowchart showing an outline of control executed by the traveling controller. FIG. 8 is a flowchart showing an outline of control executed by a work implement controller. FIG. 9 is a flowchart showing an outline of a sensor check process of a steering angle sensor; FIG. 10 is a flowchart showing an outline of a shift control. FIG. 11 is a diagram for explaining the effect of vehicle speed. FIG. 12 shows another embodiment of the speed change pedal. [Description of Signs] 1 Hydraulic mechanical transmission 1a HST section 1b Planetary gear mechanism section 2F Front wheel 2R Rear wheel 3 Shift lever 4 Throttle lever 5 Shift pedal 6 Accelerator operating section 7 Trunnion shaft 8 Electric motor 10 Control means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 29/00 F02D 29/00 B H G05G 1/14 G05G 1/14 E 13/00 13/00 F term (Reference) 3D040 AA01 AA28 AB04 AC50 AD02 AD12 AE06 AF01 AF07 3D041 AA00 AA12 AA15 AA51 AB04 AB07 AC02 AC04 AC15 AC19 AC24 AD02 AD04 AD10 AD31 AD32 AD42 AD53 AE12 AE19 AE32 3G065 CA05 CA22 EA13 FA09 GA31 AGA11 GA31 GA01 AB01 BA05 CB08 DB11 DB12 EA02 EB03 EC01 EC02 EC04 3J070 AA32 BA34 CC22 CC71 DA24 EA31

Claims (1)

Claims: 1. A hydromechanical continuously variable transmission (1) comprising a hydrostatic continuously variable transmission section (1a) and a gear mechanism section (1b) for transmitting the rotational power of an engine (E). Drive wheels (2F, 2R) via a gear type transmission (9) having a plurality of gear positions.
The work vehicle includes a throttle lever (4) for setting and maintaining an output rotation speed of the engine (E), and a shift for changing the output rotation speed of the continuously variable transmission (1). A pedal (5) is provided, and the engine (E) set and held by the throttle lever (4) at the same time as the depressing operation of the speed change pedal (5).
A shift operation device for a work vehicle, comprising an accelerator operation section (6) capable of increasing and reducing the output rotation speed of the work vehicle.