JPH1068430A - Transmission of tractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform smooth transmission by providing a clutch coupling pressure control device to switch and select the coupling pressure pattern of a clutch during the shift operation according to the automatic transmission range of a tractor and the working condition of a working vehicle to select appropriate coupling pressure of the clutch. SOLUTION: When an automatic transmission switch 71 is turned ON, the shift position according to the output signal of a shift position selection switch 72, a shift position sensor 73, a lift arm sensor 74, an engine load sensor 75, etc., is determined to perform transmission in a clutch coupling pressure control device. When the coupling pressure control of a main clutch 1 is performed in accordance with the clutch coupling pressure pattern, the clutch is coupled by dropping the hydraulic force in a condition where the main clutch is uncoupled through a proportional solenoid valve in a long time during the shift-up on the road. During the shift-down, the clutch is coupled in a shorter time than the coupling time during the shift-up.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electronically changing the traveling speed of a tractor automatically and electronically. The connection pressure of a clutch is selected appropriately according to the automatic shifting range width and the working state. It is intended to make a smooth shift.

[0002]

In the form of automating the traveling transmission of the tractor, it is necessary to automatically adjust the clutch operation because the clutch operation differs depending on each traveling condition, work condition and the like. The present invention relates to whether the traveling shift is downshifted or upshifted, and whether the shift range width is small or large, whether the implement of the tractor is lowered to the working position, or raised to the non-working position. The connection pressure adjustment when the clutch is engaged is automatically switched and adjusted depending on whether the clutch is engaged.

[0003]

According to the present invention, there is provided a clutch connection pressure control device for switching and selecting a connection pressure pattern of the clutch 1 at the time of a shift operation according to an automatic shift range of a tractor and a working state of a work machine. The tractor transmission is characterized by the following features.

[0004]

When the operator selects a predetermined shift position which is deemed appropriate for traveling, various sensors are read, and the clutch connection pressure control device determines the level of the automatic shift range and the working posture. Is determined, and one of the optimal connection pressure patterns A to E of the clutch 1 according to these conditions is selected, and the clutch 1 is controlled for connection during shifting of the transmission. Is done.

[0005] The connection pressure pattern in this clutch connection pressure control device is a shift-up pattern when the gearshift operation is a high-speed position or a low-speed position from the current position. Selected as a pattern. Also, at the time of this shift-up, as a pattern when the working machine is in a working posture with the ground down,
At an early stage as possible, the clutch 1 is brought close to the engagement position as quickly as possible to be in a half-clutch state, and thereafter the clutch 1 is gradually connected. As a pattern when the working machine is raised and is in the non-working posture, the change in the connection pressure varies depending on the width of the shift range.

For example, when traveling on a road, a pattern in which the upshift width is standard, a pattern in which the connection pressure is gradually decreased when the upshift width is wide, and a When the width is narrow, the connection pressure is controlled to a steeply decreasing pattern.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A tractor body 2 has an engine under a front bonnet 3 and a main clutch 1 and a reversing clutch 4 with an internal clutch housing 5 connected to a rear side of the engine body. A front transmission case 9 in which a transmission 6, an auxiliary transmission 7, a 4WD switching clutch 8 and the like are housed, and a rear wheel differential device 10 and a rear transmission case 11 in the rear are integrally connected to the rear side. Wheel 1
2 and the front wheels 13 are of a 4WD type capable of driving and traveling. 14 is a seat between the left and right fenders 15, 16 is a steering handle, 17 is a lift arm, and a lift cylinder 8 in a hydraulic case 18 on the rear transmission case 11
0 and the lift control valve 81 is turned up and down. Reference numeral 19 denotes a PTO shaft which drives a rotary tilling device 20 as a working machine.

[0008] The tilling device 20 comprises a tilling shaft 22 which rotates with a cultivating claw 21 disposed horizontally in the left and right direction. The lower left and right lower pins 26 of the tilling frame 23 are connected to the lower link 27, and the lower link 27
And the lift arm 17 are connected by a lift rod 28, and the vertical movement of the lift arm 17 causes the tillage device 2 to rotate.
0 can be raised above the ground to be in a non-working posture or lowered to the ground to be in a tilling working posture. 29 is a tillage cover, 30 is a flat plate.

The main clutch 1 is of a wet multi-plate type and can operate the clutch shifter 32 by stepping on a clutch petal 31. The proportional solenoid valve 3 of a hydraulic circuit 33 having a hydraulic pump P and a tank port T is provided.
It is also turned on and off by 4 and cylinder 35. The proportional solenoid valve is configured so that the clutch is disengaged when the hydraulic pressure is increased.

The reverser clutch 4 is driven by switching between forward rotation and reverse rotation from a clutch shaft 36 driven by the main clutch 1 to a reverse shaft 39 via an intermediate shaft 37 and a reverse rotation shaft 38. It is of a wet multi-plate form, and can be turned on and off by a hydraulic reversing operation on the reversing clutch F on the forward side and on and off by the reversing clutch R on the reverse side. The PTO shaft 19 is driven from the intermediate shaft 37 via a speed change clutch 40 and an interlocking shaft 41.
82 is a pressure reducing valve, and 83 is a relief valve. 84 is the left and right brake cylinders 85L, 85 of the steering brake 76
This is a steering control valve that switches R to perform braking.

The main transmission 6 receives the rotation of the reverser shaft 39 and switches the speed change clutches 42 and 43 from the first speed to the fourth speed, thereby interlocking the speed of the counter shaft 44. The transmission clutches 42 and 43 are of a synchronous type, and
3 are shifted by electromagnetic solenoid valves 45 and 46 and shift cylinders 47 and 48.

The auxiliary transmission 7 has a power shift clutch in the form of a wet multi-plate, and receives electromagnetic solenoid valves 49 and 50 and a shift cylinder 5 from a hydraulic circuit 33.
1,52. The clutch shaft 53 driven from the counter shaft 44 and the clutch shaft 54
The rear wheel differential device 10 is rotatably provided on a pinion gear shaft 55 interlocked therewith, and counter shafts 56, 5 opposed thereto are provided.
7, a clutch shaft 58, 59 is rotatably provided on one shaft 57, and a clutch 6 switched between the clutch shafts 53 and 54 by the shift cylinder 51.
By providing 0 and 61, it is possible to switch from the neutral position to low speed L and high speed H. The clutch 6 which is switched by the shift cylinder 52 between the clutch shafts 58 and 59.
2, 63 can be switched from the neutral position to the ultra low speed LL and the medium speed M.

A rear wheel differential device 10 through the auxiliary transmission 7
A front wheel take-out shaft 64 that is interlocked with the front wheel 13 is transmitted from a pinion gear 55 that is interlocked with the front wheel 13.
A WD switching clutch 8 is provided, and an electromagnetic solenoid valve 70 of the hydraulic circuit 33 and the shift cylinder 66
When the clutch 67 is engaged from 2WD at the neutral position N,
When the interlocking shaft 65 is directly connected to form a normal 4WD, and when the clutch 68 is engaged, the interlocking shaft 6 is
5 can be a double speed 4WD that transmits to almost twice the rotation speed, and can be operated as a mode for turning steering.

In the automatic shifting by the clutch connection pressure control device, the clutch connection pressure control can be operated by turning on the automatic transmission switch 71. The clutch connection pressure control device includes a shift position selection switch 72 operated by the operator, a shift position sensor 73 that detects a shift position based on the current combination of the main speed change and the sub speed change, and a state of the tillage device 20 that is a working machine. A lift arm sensor 74 composed of a potentiometer, an engine load sensor 75, and the like are provided.
When the shift position is selected, the shift is performed, and the connection pressure control of the main clutch 1 is performed according to the flow as shown in FIG.

The clutch connection pressure pattern of the clutch connection pressure control device is set, for example, in the form of A to E in FIG. In pattern C, when shifting up,
Moreover, it shows the state of traveling on the road with the working machine raised, and this is a standard pattern. The graph shows the change over time t of the output current i from the clutch connection pressure control device to the proportional solenoid valve 34 or the hydraulic pressure p in the shift cylinder 35 over time. Then, the clutch 1 is connected by lowering.

On the other hand, at the time of downshifting, as shown in the D pattern, the hydraulic pressure p is suddenly lowered at the initial stage and then gradually lowered irrespective of the raising / lowering position of the work machine, and the C pattern is changed. The clutch is connected in a time t1 shorter than the connection time t. In the E pattern, the work machine is lowered by upshifting and is in the tilling state by the tilling device 20, and is set at an intermediate position between the C pattern and the D pattern.

The pattern A shows the same conditions as the pattern C and a case where the shift range width is wide, so that the oil pressure p decreases more gently than the pattern C. On the other hand, the B pattern indicates a case where the shift range width is narrow, and therefore, the connection of the clutch 1 is performed as the oil pressure p decreases more rapidly than the C pattern. The clutch connection pressure control device C
Although the target of the PU is instructed as the main clutch, the PU may be used in a mode in which gear shifting is performed using other clutches. Further, the present invention can also be used in a mode in which the main transmission is automatically shifted by performing a sub-shift using the sub-shift lever as the shift position selection switch 72.

FIG. 6 is different from the above example in that the lift arm 17 is automatically raised by the turning angle of the steering handle 16 to bring the working machine into the non-working posture and to output the steering brake 76. One side rear wheel 12
When the vehicle speed detected by the vehicle speed sensor 77 is in the speed change range of 3,5 to 5 km / h, the steering angle of the steering wheel 16 is determined by the control device CPU2 of the auto lift brake which applies the brake to the vehicle to perform the steering turn. ,
After automatically shifting down the transmissions 6 and 7 by one or two gears, the steering brake 76 is activated.
A pivot turn by the steering brake 76 in the speed change range is prohibited to ensure safety.

Thus, the vehicle speed after the end of the steering turn is:
Although it is in a state of being decelerated by one stage or two stages, when the turning is completed, the lift arm 17 is lowered by operating the tilling device 20 by lowering the finger-up lever 78, and the tilling device 2 is rotated.
As a grounding sensor 79 for detecting whether or not the tilling apparatus 20 has touched down after performing a shift up operation after 0 has touched down, a lift arm sensor for detecting the lift angle of the lift arm 17 or a tilling soil It may be configured to detect the angle by the tillage depth sensor or the like that detects the angle of the leveling plate 30 for leveling the surface.

[Brief description of the drawings]

FIG. 1 is a diagram of a traveling transmission mechanism and a block diagram of a clutch connection pressure control device.

FIG. 2 is a hydraulic circuit diagram.

FIG. 3 is a graph showing a clutch connection pressure pattern.

FIG. 4 is a flowchart of clutch connection pressure control.

FIG. 5 is a side view of the tractor working machine.

FIG. 6 is a block diagram of a vehicle speed control showing a partially different embodiment,
The flowchart.

[Explanation of symbols]

 1 Clutch A Connection pattern B Connection pattern C Connection pattern D Connection pattern E Connection pattern CPU Clutch connection pressure control device

Claims (1)

[Claims] 1. A clutch connection pressure control device for switching and selecting a connection pressure pattern of a clutch 1 at the time of a shift operation according to an automatic shift range width of a tractor and a working state of a work machine is provided. Transmission of tractor.