JP2003185006A - Transmission control device of working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem in a working vehicle decelerating the output speed of a hydromechanical transmission (HMT) by detecting the depressed amount of a brake pedal generally energized by a spring in non-braking direction that the vehicle is abruptly accelerated when the brake pedal is released. <P>SOLUTION: An operating speed is detected by the depressed amount sensor for the brake pedal. When the speed is directed in the non-braking direction and higher than a predetermined speed, the output rotation control of the HMT by the normal depressed amount is interrupted, and a vehicle speed is returned to a gear shift lever holding position by a speed increase line L1 based on a preset elapse of time. Also, when the vehicle comprises a working machine for the ground, a PTO clutch is disengaged when the brake pedal is depressed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a shift control device for a work vehicle having a hydromechanical continuously variable transmission such as a tractor and a lawn mower.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Unexamined Patent Publication No. 5-215200, a hydromechanical continuously variable transmission (HMT) for rotating the engine has a hydrostatic continuously variable transmission and a gear mechanism. It is known and it is known to mount this HMT on a construction vehicle or a cargo handling vehicle.

[0003]

However, when working with the ground working machine such as the rotary working machine mounted on the working vehicle as described above, even if the brake pedal is depressed, the H
Since the output rotation of the MT is still transmitted to the drive wheels, and the rotational power from the PTO shaft is still transmitted to the ground work machine, there is a problem that it becomes a propulsive force of the vehicle and the braking distance becomes long.

The brake pedal is generally urged toward the brake release side by a spring or the like. However, if the output rotation of the HMT is controlled according to the pedal position, when the pedal is released. There is a problem that the vehicle accelerates rapidly.

[0005]

SUMMARY OF THE INVENTION In view of the above problems, the present invention has a shift control device for a work vehicle configured as follows. That is, in the invention of claim 1, the rotational power of the engine (E) is supplied to the hydrostatic stepless transmission (1a) and the gear mechanism (1).
b) is transmitted to the drive wheels (2F, 2R) via a hydraulic mechanical continuously variable transmission (1), and the output rotational speed of the transmission (1) is moved forward across the neutral position. And a work vehicle which is held by a set position of a lever (3) which is operated to move in a reverse operation range, a ground work machine (R) which is movably connected to the work vehicle and a power to the ground work machine (R). PTO shaft (11) for transmitting the power and the PTO
A clutch mechanism (C which turns on and off the power transmission to the shaft (11)
3) is provided and the brake pedal (8) of the vehicle is provided.
Is provided with a sensor (8s) for detecting the depression operation of the pedal (8), and when the brake pedal (8) is depressed, the output rotation speed of the transmission (1) is set by the lever (3). The clutch mechanism (3) for decelerating from the rotational speed according to the depression position of the brake pedal (8) and transmitting the power to the PTO shaft (11) is turned off.
A shift control device for a work vehicle is provided with a control means (10) for operating.

(Operation of Claim 1) According to the invention of Claim 1 configured as described above, while the output rotation of the hydromechanical continuously variable transmission (1) is set and held by the lever (3),
When the brake pedal (8) is depressed, the output speed of the hydromechanical continuously variable transmission (1) is decelerated and the drive wheels (2F, 2R) are driven in preference to the lever position.

According to the second aspect of the invention, the sensor (8s) for detecting the depression operation of the brake pedal (8).
Detects the operation speed of the pedal (8), and when the operation speed is faster than a preset speed, the output is performed based on a predetermined acceleration pattern that prevents sudden acceleration regardless of the depression position. The shift control device for a work vehicle according to claim 1, further comprising a control means (10) for returning the rotation speed.

(Operation of Claim 2) According to the invention of Claim 2 configured as described above, when the moving speed is high when the brake pedal (8) is released, the transmission (1) corresponding to the pedal position. The output control of the transmission (1) is controlled based on a preset speed-up pattern.

[0009]

As a result, in the invention of claim 1, even if the output rotation of the hydromechanical continuously variable transmission (1) is held by the lever (3), if the brake pedal (8) is depressed, the drive wheel ( (1R) is braked, the output rotation of the hydromechanical continuously variable transmission (1) is decelerated, and the power transmission to the working unit is also cut off, so that the braking distance can be shortened.

According to the second aspect of the invention, the hydraulic mechanical continuously variable transmission (1) is normally operated by operating the brake pedal (8).
Even if the output control is performed, if the brake pedal (8) is released, sudden acceleration can be prevented and the operability of the vehicle can be improved.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described for an agricultural tractor T which is a work vehicle. First, the structure of the tractor T will be described.

As shown in FIG. 2, the tractor T is equipped with a diesel engine E inside the bonnet 11, a front axle case for supporting the left and right front wheels 2F, 2F is provided below the engine E, and a rear portion of the engine E will be described later. A transmission case 12 that houses a hydraulic mechanical continuously variable transmission (hereinafter referred to as HMT1) and the like is connected, and a rear axle case 13 that supports rear wheels 2R, 2R is connected to the left and right of the rear portion of the case 12. .

A cabin 14 surrounding the cockpit 16 is provided at the rear of the bonnet 11 above the mission case 12, and a meter panel 15 having various notification devices such as a pilot lamp and a liquid crystal monitor is provided inside the cabin 14, and behind it. A steering wheel post 21 is provided on which the steering wheel 20 is provided, and a steering wheel turning angle sensor 20s is provided inside the post 21 as a means for detecting a turning operation of the vehicle body.

Further, on one side surface of the handle post 21, there is provided an accelerator lever 22 for setting and holding the number of revolutions of the engine E. Also, the handle post 2
Below 1, there is a clutch pedal 23 and an accelerator pedal 2
4. A single brake pedal 8 and the like are provided, and the rotation base of the clutch pedal 23 is provided with a spring and a damper for urging power transmission of a main clutch, which will be described later, to the entrance side, and the pedal 2.
A potentiometer-type depression position sensor 23s is provided as a means for detecting the depression operation of No. 3, and a spring is also provided at the base of the accelerator pedal 8 so as to accelerate the engine speed set and held by the accelerator lever 22 only when the depression is performed. A potentiometer-type depression position sensor 8s is provided as means for detecting the depression operation of the damper and the pedal 8.

In the vicinity of the cockpit 16, an HMT shift lever 3 for shifting the output rotation of the HMT is provided, and a friction material is provided at the rotation base of the lever 3 to hold the set position. There is. Further, a work machine elevating lever 25 and an auxiliary gearshift lever 29 are provided in the vicinity of the cockpit so as to project, and lever position sensors 3s, 25 for detecting the operating position at the respective lever bases.
s, 29s are provided.

Furthermore, on the side of the cockpit, an independent PTO ON / OFF switch 27A for turning ON / OFF the rotation of the PTO shaft 26 at the rear of the vehicle body and a PTO drive mode for setting ON / OFF of PTO control which will be described later. Switch 27
B, the front wheel 2F is accelerated when turning, and the rear wheel 2 inside the turn
A turning control switch 28 for turning on and off the so-called turning control for braking the R and raising the working machine R to the non-working position is provided.

The various setting devices 27, 28 ... And the sensors 3s, 9s ... Are connected to the controller group which is the control means 10 below the cockpit 16. Further, a cylinder case 30 having a hydraulic cylinder for raising and lowering the working machine is provided at the rear part of the vehicle body of the tractor T, and a lift arm 31 supporting the case 30 to the left and right is vertically rotated by expanding and contracting the piston of the cylinder. On one side of the lift arm 31, a lift arm angle sensor 31s is provided on the rotation base. The top link 32 and the left and right lower links 33, 33 are provided at the rear of the vehicle body.
Is provided with a three-point link mechanism, and various working machines such as a ground working machine are connected to the link mechanism.

In the example shown in FIG. 2, the rotary working machine R is connected to the rotary working machine R.
The rotation of the TO shaft 26 is input through a universal joint to drive the rotary pawl 36. Thereby, in the working machine controller 10b described later,
The solenoid 34 of the proportional flow control valve for raising the working machine or the solenoid 35 of the proportional flow control valve for lowering the working machine is energized so that the operating angle of the lever 25 for raising and lowering the working machine coincides with the set angle of the lift arm 31. The configuration is such that control (position control) for raising and lowering the machine R is performed.

Next, the power transmission structure of the tractor T will be described with reference to FIG. The rotational power of the engine E is
A first shaft 41 that is taken out from the engine output shaft and is supported at the front part inside the transmission case 12 via the main clutch 40.
Transmitted to. The main clutch 40 is provided with a clutch operating hydraulic cylinder 39 as a main clutch operating actuator, and in response to an energization command from the controller 10a, the main clutch 40 is operated similarly to the clutch pedal 23.
It is configured to turn on and off.

The first shaft 41 has a P on the power side.
A PTO power branching gear 42 is provided as a branch part of the TO power, and a rear end part of the coaxial shaft 41 is connected to a pump input shaft 43 of the HMT 1. In addition, the HMT1
Is a main transmission device for traveling system power composed of a hydrostatic continuously variable transmission portion (hereinafter referred to as HST 1a) and a planetary gear type transmission mechanism portion 1b. The main transmission device for the HST transmission lever 3 corresponds to the operation position of the HMT transmission lever 3. By changing the tilt angle of the swash plate in the pump P, that is, the rotation angle of the trunnion shaft 4, the output rotation speed of the motor M is continuously changed from normal rotation to reverse rotation.

The trunnion shaft 4 is provided with a potentiometer type angle sensor 6 for detecting a coaxial angle and an electric motor 5 as an actuator for operating the trunnion shaft.
The rotation position of the trunnion shaft 4 can be forcibly changed from the set position of the HMT shift lever 3 by driving the motor 5.

Although the HMT gear shift lever 3 and the trunnion shaft 4 are electrically interlocked here, both members 3 and 4 are mechanically interlocked by a link mechanism or a cam mechanism. Is also good. Further, the pump input shaft 43 is provided so as to project further rearward from the HST main body, and is connected to a carrier 44 of a planetary gear mechanism portion 1b described later.

The power transmission path of the traveling system is HST.
A second shaft 45 is arranged behind the pump input shaft 43 of 1a, and a planetary gear mechanism 1b and an HMT for measuring the number of revolutions output from the gear mechanism 1b are arranged on the second shaft 45 in order from the front.
A first clutch mechanism (hereinafter, referred to as HM) for turning on / off the power transmission output from the output rotation detecting gear 46 and the gear mechanism 1b.
A T-clutch C1), a first input gear 48 for taking in rotation of a motor output shaft 47 of the HST 1a described later are provided, and a gear type auxiliary transmission device 49 is provided behind the input gear 48.

The planetary gear mechanism 1b includes a plurality of planetary gears 50, an internal gear 51 that meshes with outer peripheral edge portions of the planetary gears 50, and rotates integrally with the second shaft 45, and the second shaft 45. Of the planetary gears 50 and the sun gear 52 that meshes with the inner peripheral edge portion of the planetary gears 50.
4 and is integrally connected to the pump input shaft 43. Further, the sun gear 52 is configured to idle on the second shaft 45, and the rear portion thereof is integrally configured with the second input gear 53.

Further, the power transmission path on the motor M side of the HST 1a is provided with a second output gear 54 meshing with the second input gear 53 at an intermediate portion of the motor output shaft 47, and a second clutch mechanism (hereinafter referred to as HST clutch). A first output gear 55 that meshes with the first input gear 48 is provided via C2).

Further, the HMT clutches C1 and HST
The clutch C2 is hydraulically pressure-bonded by an energization command from the traveling controller 10a described later.
As a result, the rotational power of the engine E is transferred to the auxiliary transmission 4
9 is transmitted, the HMT clutch C1 is “on” and H
With the ST clutch C2 set to "off", 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 to drive the second shaft 45 (HMT mode), or the HMT clutch C1 is set. "Off" and HS
With the T-clutch C2 set to "ON", only the rotation of the motor output shaft 47 is transmitted to the sub transmission 49 through the engagement of the first input / output gears 55 and 48 (HST mode). ing.

The rotation obtained from the HMT mode is detected by an HMT rotation detection sensor 46s provided close to the output rotation detection gear 46 of the HMT1, and the rotation obtained from the HST mode is detected by the second output. Gear 5
The vehicle speed in each mode is indirectly detected by the HST rotation detection sensor 54s provided close to the No. 4 vehicle.

As a result, as shown in FIG. 4, in the tractor T, when the HMT gear shift lever 3 is tilted into the reverse range and the low speed range of the forward movement, which exceeds the neutral position and reaches the predetermined vehicle speed S1, in the HST mode, The vehicle is configured to travel in the HMT mode in a forward high speed range that exceeds the predetermined vehicle speed S1 when moving forward.

The sub transmission 49 is a transmission having two shift positions of "high" and "low", and the rotational power reduced at the same shift position is transferred to the left and right via the rear wheel differential mechanism 57. The power is transmitted to the rear wheel drive shaft 56 and the rear wheel 2R, and by the front wheel power branch gear provided on the power-hand side of the rear wheel diff mechanism 57, it is also transmitted to the front wheel 2F via the front wheel speed increasing device 58 and the front wheel diff mechanism. It is configured to be communicable.

A disc type brake mechanism 60 is provided on the left and right rear wheel drive shafts 56 to rotate the coaxial shaft 56, that is, to extend and retract a piston of a hydraulic cylinder 61L (61R) for braking, which serves as a brake actuator for the rear wheel 2R. The left and right are independent or the left and right are integrally braked.

On the other hand, in the transmission path of the PTO system power, a driven gear 65 which meshes with the PTO system power branch gear 42 is provided at the front part inside the mission case 12, and a third gear supporting the driven gear 65 is provided. A clutch mechanism (hereinafter, referred to as PTO clutch C3) for turning on / off the transmitted power is provided on the lower power side of the shaft 66. In addition, the PTO
The clutch C3 is configured to be turned on and off by hydraulic pressure according to an energization command from the controller 10b described later.
Also, on the power side of the PTO clutch C3, a PTO
A speed change unit 67 is provided to change the rotation speed of the PTO shaft 26 in several stages.

Next, the control system of the tractor T will be described with reference to FIG. The control means 10 of the tractor T is
Travel controller 10a for processing control related to gear shifting
And a work machine controller 10b that processes control related to the work machine. Each controller has a CPU that processes various signals, a RAM that temporarily stores these signal information, and an EEPROM that stores various control programs.
It is configured to have storage means such as M. Further, the controllers 10a and 10b are connected to each other through a communication line and are configured to transmit and receive sensor information and output information to and from each other.

The traveling controller 10a uses the input section for the steering wheel turning angle sensor 20s, the lever position sensor 3s at the base of the HMT shift lever 3, the trunnion shaft angle sensor 6, the auxiliary shift lever position sensor 29s, and the clutch pedal depression amount. The sensor 23s, the brake pedal depression amount sensor 8s, the HMT rotation sensor 46s, the HST rotation detection sensor 54s, and the like are connected and provided. The output section also includes an electric motor 5 for forcibly changing the rotation position of the trunnion shaft 4, a solenoid 69 of a switching control valve for sending pressure oil to a hydraulic cylinder for operating the main clutch, and an HMT clutch C1.
Solenoid 70, HS of proportional flow control valve for crimping operation
Solenoid 71 of the proportional flow control valve for crimping the T-clutch C2, the left and right rear wheel brake hydraulic cylinders 61
Solenoid 7 of proportional flow control valve that operates L and 61R
2L, 72S, a solenoid 74 of a switching control valve for operating the front wheel speed increasing device 58, etc. are connected and provided.

Further, the working machine lifting controller 10b
Is connected to the input unit with the swing control switch 28, the lever position sensor 25s at the base of the work machine lifting lever 25, the lift arm angle sensor 31s, the independent PTO on / off switch 27A, the PTO drive mode setting switch 27B, and the like. The solenoids for raising and lowering the proportional flow rate control valve for sending pressure oil to the cylinder for raising and lowering the working machine, and the solenoid 75 for the switching control valve for opening and closing the PTO clutch C3 are connected to the output section. Are provided.

In the tractor T configured as described above, when the engine E is started after the power is turned on, various controls are executed as shown in FIGS. 6 to 10. The flowchart shown in FIG. 6 shows an outline of the control executed by the traveling controller 10a. The controller 10a reads in STEP 1 the connection states and detection states of various setting devices, switches, and sensors, and in STEP 2, the steering wheel turning angle is determined. It is determined whether the angle is less than or equal to a predetermined angle.
If it is O, it is determined to be a turning operation in the field, and after turning control is performed, other processing is further performed to return.

The flow chart shown in FIG. 7 shows an outline of the control executed by the working machine controller 10b. The controller 10b reads in STEP 1 the connection states and detection states of various setting devices, switches, and sensors,
After the PTO control is performed in STEP2 and the position control is performed in STEP3, another process is further performed to return.

The shift control will be described in detail with reference to FIG. In the traveling controller 10a, first ST
In EP1, the operating direction and operating speed of the brake pedal 8 are calculated, and in STEP2, the depression position of the pedal 8 is determined. If the pedal depression position is the maximum depression position, the process proceeds to STEP3, the HST clutch C2 is set to "ON", the trunnion shaft 4 is set to the neutral position, and the left and right brake hydraulic cylinders 61L and 61R are set to the operating state. Hold. If the determination in STEP2 is the non-depressed position, that is, the initial position where only the biasing force of the spring is applied, the process proceeds to STEP4 and the HMT
The trunnion shaft 4 is rotated corresponding to the position of the speed change lever 3 to change the output rotation of the HST 1a.

If it is determined in STEP 2 that the operation position of the brake pedal 8 is between the maximum depressed position and the non-depressed position, the process proceeds to STEP 5 to determine the operation direction of the pedal 8. When the operation speed in the depressing direction is slower than a predetermined speed, the HMT clutch C1 and the HST clutch C2 are set according to the vehicle speed and the pedal position.
And the angle of the trunnion shaft 4 is changed by the electric motor 5.

The above example will be described with reference to FIG.
The traveling controller 10a stores the set holding position of the speed change lever 3, and the vehicle speed is reduced by driving the electric motor 5 according to the depression position of the brake pedal 8. Conversely, when the pedal 8 is released, the stored value is stored. Return the vehicle speed to. Further, here, the auxiliary transmission 49 is "high" and "low".
The sub-shift lever position sensor 29 determines which is set.
s, the depression stroke of the pedal 8 and the deceleration rate of the vehicle speed are set to be constant in any case. As a result, the operator can always adjust the vehicle speed with a constant feeling.

When the operation speed of the brake pedal 8 is high in STEP8, it is assumed that the brake pedal is in a sudden braking state, and the HMT clutch C1 or the HST clutch C2 is assumed.
Intermittently turning on / off the pressure bonding to turn on / off the power transmitted to the front wheels 2F or the rear wheels 2R to shorten the braking distance of the vehicle.

Further, in STEP 5, the brake pedal 8
When the pedaling operation is detected and it is determined in STEP 6 that the operation speed is equal to or higher than the predetermined value, it is determined that the pedal 8 has returned to the initial position only by the biasing force of the spring, or a state close to this. The clutches C1 and C2 and the trunnion shaft 4 according to the position of the pedal 8,
That is, the control of the vehicle speed is restrained, and the vehicle speed is increased in a shift pattern according to the passage of time as shown in FIG.

The vehicle speed increasing pattern shown in FIG. 1 is H
A case is shown in which the MT gear shift lever 3 is set and held at an angle of α1 and the brake pedal 8 is released, and when the return time of the pedal 8 is shorter than t2, a speed increase that does not cause sudden acceleration previously stored in the EEPROM. The trunnion shaft 4 is returned to the set position based on the line L1. Time t in FIG.
1 fully releases the brake pedal 8 and the pedal 8
Indicates the time to return only by urging the spring.

As a result, in the tractor T, the output rotation of the HST 1a is decelerated when the brake pedal 8 is depressed, so that the braking distance can be set short. Further, when the brake pedal 8 is suddenly released, the angle adjustment of the trunnion shaft 4 depending on the pedal position is restrained and the vehicle speed is increased based on a preset speed increasing line, so that sudden acceleration can be prevented. The operability of the vehicle can be improved.

As the speed increasing pattern for preventing the sudden acceleration, in addition to the regulation by the pedal return time as in the speed increasing line L1, the angle of the trunnion shaft 4 is gradually returned every several percent. Configuration and hydraulic cylinder 6 for the brake
The vehicle speed may be restored by using another actuator in combination, such as brake release by 1L or 61R.

Turning control performed by the traveling controller 10a will be described below with reference to FIG. In this turning control, in STEP 1, it is determined whether or not the turning control switch 28 is turned on.
In step 2, the depression operation of the brake pedal 8 is determined, and if it is also YES, in step 3, the brake hydraulic cylinder 61L (6L6
1R), and then in STEP 4, the working machine is raised to the non-working position, and in STEP 5 the front wheels 2F are moved to the rear wheels 2R.
The output speed of the HST 1a is further decelerated to the end.

The PTO control performed by the working machine controller 10b will be described with reference to FIG.
First, in STEP 1, it is determined whether the independent PTO switch 27A is ON or in STEP 2 whether the PTO drive mode switch 27B is ON.
In the case of ES, the PTO clutch C3 is turned off (STEP 6) when the HMT shift lever 3 is operated to the stop position or the brake pedal 8 is operated to the maximum depression position.

As a result, when the ground work machine such as the rotary work machine R is mounted on the tractor T, the power to the work machine is shut off. Therefore, similarly to the shift control, the rapid acceleration due to the dashing is prevented. Further, it is possible to prevent engine stalling due to overload at the time of stop.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a vehicle speed and a return time when a brake pedal is operated.

FIG. 2 is an overall side view of a tractor.

FIG. 3 is a diagram showing a power transmission structure of a tractor.

FIG. 4 is a diagram showing the relationship between vehicle speed and drive mode.

FIG. 5 is a diagram showing a connection state of a controller.

FIG. 6 is a flowchart showing an outline of control executed by the traveling controller.

FIG. 7 is a flowchart showing an outline of control executed by a work machine controller.

FIG. 8 is a flowchart showing an outline of shift control.

FIG. 9 is a flowchart showing an outline of turning control.

FIG. 10 is a flowchart showing an outline of PTO control.

FIG. 11 is a diagram showing a decelerated state of the vehicle speed when the brake pedal is depressed from the holding position of the HMT shift lever.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F16H 59:68 F16H 59:68

Claims (2)

[Claims] 1. A drive wheel (2F) is provided with rotational power of an engine (E) via a hydromechanical continuously variable transmission (1) comprising a hydrostatic continuously variable transmission (1a) and a gear mechanism (1b). , 2
R), and the output rotation speed of the transmission (1) is held by a set position of a lever (3) which is operated to move in a forward operation range and a reverse operation range with a neutral position interposed therebetween. The work vehicle has a ground work machine (R) that is vertically movable, a PTO shaft (11) that transmits power to the ground work machine (R), and power transmission to and from the PTO shaft (11). A clutch mechanism (C3) is provided, and a brake pedal (8) of the vehicle is provided with a sensor (8s) that detects a depression operation of the pedal (8). When the brake pedal (8) is depressed, the shift speed is changed. A clutch mechanism for decelerating the output rotation speed of the device (1) from the set rotation speed of the lever (3) according to the depression position of the brake pedal (8) and transmitting power to the PTO shaft (11). 3) "Off" shift control device for a working vehicle, characterized in that it comprises control means (10) to operate. 2. A sensor (8s) for detecting a depression operation of the brake pedal (8) detects an operation speed of the pedal (8), and when the operation speed is faster than a preset speed, the depression operation is performed. 2. The shift control of a work vehicle according to claim 1, further comprising control means (10) for returning the output rotation speed based on a predetermined acceleration pattern that prevents sudden acceleration regardless of the position. apparatus.