JPH0646249Y2 - Drive control switching device for power take-off shaft in agricultural tractor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a clutch follow-up type drive control for stopping a power take-off shaft in an agricultural tractor so as to follow the depression of a traveling clutch pedal and stop the drive shaft. The present invention relates to a drive control switching device for a power take-off shaft, which can be switched to a clutch independent drive control for maintaining the state as it is.

[Problems to be Solved by Prior Art and Invention] Generally, the drive system of the power take-out shaft (hereinafter referred to as "PTO shaft") provided with this kind of agricultural tractor is roughly divided into the drive clutch pedal and the drive clutch pedal. In this case, the clutch independent drive control (independent control, hereinafter referred to as "IND-PTO control") continues to drive the PTO axis regardless of this.
Abbreviate) and follow the depression of the traveling clutch pedal
There are two types of clutch follow-up drive control (standard control, abbreviated as "STD-PTO control" hereafter) that stops the PTO axis, but these two types of switching are used in agricultural tractors to operate the drive type switching operation tool. There are various types that can deal with the diversification of work in various ways. However, in the case where the drive type of the PTO shaft can be switched in this way, when performing ground work such as plowing work, if the work is performed in the IND-PTO control state, the traveling clutch is depressed. Even if the aircraft is stopped, the PTO shaft will continue to be driven and ground work will continue, so the work depth at that location will be deep, and the work depth will be disturbed and ground work with high accuracy will be performed. As a result, it is necessary to always switch the drive type switching operation tool to the STD-PTO control side for ground work, but this is often forgotten, and there is a countermeasure for this. There is a strong demand.

[Means for Solving Problems] The present invention has been made in view of the above circumstances, and was devised with the object of providing a drive control switching device for a power take-off shaft in an agricultural tractor capable of eliminating these drawbacks. Then, based on a command from the drive type switching operation tool, a control command is issued to the power connection / disconnection mechanism provided in the transmission system to the power extraction shaft and the drive type switching operation tool of the power extraction shaft. Connected via the control unit, the power disconnect mechanism to the depression of the traveling clutch pedal,
In the agricultural tractor configured to be able to switch between the clutch follow-up drive control that switches to the disconnection state by following and the clutch independent drive control that maintains the continuous state, in the control unit, the control unit includes a working unit for ground work. It is connected to the work depth control switching operation tool, and when this is set to work depth control, it is called clutch independent type drive control. It is characterized in that work depth control determination means for issuing a control command is provided.

With this configuration, the present invention automatically controls the drive of the PTO axis by the STD-PTO control when performing ground work in the working depth control state even if the IND-PTO control is set. It was made possible.

[Embodiment] Next, an embodiment of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 denotes a traveling machine body of an agricultural tractor, and a rotary tilling type working section 2 which is an example of a ground working section is attached to a rear portion of the traveling machine body 1 via a lifting link mechanism 3. The working unit 2 is configured to move up and down by the lift arm 5 swinging up and down based on a command from the control unit 4 described later, and the connecting shaft 7 that is interposed between the PTO shaft 6 and the working shaft 2. Power is input from the engine side via.

In FIG. 3, a lift arm cylinder 27 that controls the lifting movement of the lift arm 5 and a lift rod 13 provided between the lift arm 5 and the lower link 3b of the lifting link mechanism 3 are provided on either the left or right side. The hydraulic circuit diagram for the lift rod cylinder 13 and the hydraulic clutch 23 provided in the power transmission system for the PTO shaft 6 is shown. The lift arm cylinder 27 expands and contracts by switching between the ascending solenoid valve 27a and the descending solenoid valve 27b. Actuated and lift rod cylinder 13
Although a is configured to be expanded and contracted by switching the tilt control solenoid valve 28, and the hydraulic clutch 23 is intermittently operated by switching the clutch solenoid valve 29. , A priority valve 30 is provided, and the pressure oil supply amount to the lift arm cylinder 27 side is adjusted based on the engine speed as described later. The tilt control solenoid valve 28 is connected to the outlet side, and the amount of pressure oil supplied to the lift rod cylinder 13a can be adjusted by switching the valve 30.

The control unit 4 is configured by using a microcomputer, and the control unit 4 includes an arm angle detection sensor 8 for detecting the swing angle of the lift arm 5, and a top link 3a of the lifting link mechanism 3. Draft detection sensor 9 for detecting the draft force, position detection sensor for detecting the lever position of the position lever 10 for setting the working height
11, a tilt detection sensor 12 that detects the tilted state of the traveling body 1 with respect to the horizontal direction, a lift rod sensor 14 that detects the extension / contraction length of the lift rod cylinder 13a, and a rotation speed that detects the rotation speed of the engine. Sensors such as the detection sensor 26, or inclination control switching switch 15, draft control switching switch 16, PTO shaft drive type switching switch 17, sensitivity switching switch 18, safety switch 22 for detecting depression of the traveling clutch pedal 21 ( Safety switch
22 is set so that the engine can be started only when the traveling clutch pedal 21 is depressed to switch it to ON), switches such as the plowing depth control switching switch 24, and the draft setting device for setting the draft force. 19, data from setting devices such as a tilt setting device 20 for setting the left-right tilting state of the working unit 2 and a plowing depth setting device 31 for setting the plowing depth are input, and the control unit 4 A control command is output to each actuating unit described later based on the input data.

Next, the control system procedure will be described with reference to the flow chart shown in FIG. First, regarding the control based on the switching of the drive system of the PTO shaft 6,
It is determined whether the drive type switching switch 17 is set to the STD-PTO control. If YES is judged as set, then the safety switch 2
2 is in the OFF state (that is, the traveling clutch pedal 21 is not depressed), it is determined whether or not
If YES is determined as being OFF, an ON command is issued to the clutch solenoid valve 29 to send the pressure oil from the hydraulic pump P to the hydraulic clutch 23 to cause the clutch to move.
23 is set to continue.

Further, if the determination is NO, that is, the safety switch 22 is in the ON state (that is, the state where the traveling clutch pedal 21 is depressed), an OFF command is issued to the clutch solenoid valve 29. Hydraulic clutch 23
Is controlled to be in a disconnected state.

On the other hand, if the PTO axis drive type switching switch 17 is not set to STD-PTO control and a NO judgment is made, it is further judged whether or not it is set to IND-PTO control and set. If NO is determined as not (that is, the switch 17 is set to the OFF position), an OFF command is issued to the clutch solenoid valve 29 and the power transmission to the PTO shaft 6 is cut off. If YES is determined as being set, it is further determined whether the plowing depth control switching switch 24 is set to OFF, and YES is determined as being made here. Then, an ON command is issued to the clutch solenoid valve 29 to control the hydraulic clutch 23 to be in the continuous state. On the other hand, if NO is determined as not set, the drive type switching switch 17 Is controlled so that it is in the same state as when it is determined that the is set to STD-PTO control.

As described above, when the drive type switching switch 17 is set to the IND-PTO control, the hydraulic clutch 23 is maintained in the continuous state even if the traveling clutch pedal 21 is depressed when the driving depth control state is not set, and accordingly, the traveling clutch is maintained. Even if the airframe is turned off by turning off, the PTO shaft 6 continues to be driven regardless of this and power is transmitted to the working unit 2 to perform clutch independent drive control capable of performing work. However, in this state, if the plowing depth control switching switch 24 is turned on to perform tilling control, the drive type switching switch
Even if 17 is set to the IND-PTO control, this is ignored, and the hydraulic clutch 23 automatically switches between on and off depending on whether the safety switch 22 is turned on or off, that is, whether or not the traveling clutch pedal 21 is depressed. Therefore, even if the drive type switching switch 17 is not switched to the STD-PTO control as in the conventional case and is kept in the IND-PTO control, the working unit 2 is stopped following the airframe stop and the plowing is continued. It is possible to reliably prevent the depth from becoming too deep, and it is possible to perform highly accurate plowing depth control.

Further, in the embodiment, in addition to the drive type switching control of the PTO shaft 6, the pressure oil supply amount to the lift arm cylinder 27 is maintained substantially constant even when the rotation speed is low such as when the engine is started. The priority valve 25 provided as much as possible can be effectively used to control the switching of the hydraulic pressure supply amount to the lift rod cylinder 13a. That is, as shown in FIG. 6, in the system start state, the engine rotation speed is detected by the rotation speed detection sensor 26, and the detected value C is smaller than a preset set value D (C <D). If it is judged that it is small and YES is judged, the priority valve 25 is turned off.
Switching to the state to regulate the flow of pressure oil through the valve 25,
As a result, the required amount of pressure oil from the hydraulic pump P is supplied to the lift arm cylinder 24 side so that the lift arm cylinder 24 can be expanded and contracted without delay when the engine speed is low. . When the engine speed becomes higher than the set value D and NO is determined, it is further determined whether the tilt control switching switch 15 is ON (that is, the tilt control state) and OFF.
If NO is determined, the priority valve 25 is controlled to the OFF state and the lift arm cylinder 2
The required amount of pressure oil is supplied to the 4 side.

If YES is determined as being determined to be ON by the determination of the tilt control switching switch 15, the lift rod cylinder 13a is further out of the low speed operation range (that is, the lift control cylinder 13a is significantly deviated from the target tilt control attitude). If it is not outside the range (that is, close to the target tilt control state), the priority valve 25
Is controlled to the OFF state and the oil passage through the valve 25 is closed, but if YES is judged as being out of range, the priority valve 25 is turned on and the priority valve 25 is turned on.
An oil passage passing through 25 is opened, whereby a large amount of pressure oil is supplied to the oil passage on the side of the lift rod cylinder 13a, and high speed control is performed.

Thus, in this embodiment, when the engine speed is low,
A priority valve provided to control the amount of pressure oil supplied to the lift arm cylinder 27 so as not to decrease.
25 can be used as a speed adjusting valve that switches the control speed during tilt control, and therefore, it is not possible to effectively use dual functions of members, and inching operation is required to reduce the control speed. Therefore, the expansion / contraction speed of the lift rod cylinder 13a can be increased / decreased by the continuous ON operation of the valve, so that stable, fine and precise tilt control without any shock can be performed.

Further, this is a lifting control of the lift arm 5 as shown in the flow chart of FIG. 7 when the draft control switching switch 16 is turned on and the draft control is required when the working unit 2 is a plow working machine. Is going to do. That is, when the switch 16 is ON in the system start state, the monitor lamp is turned on (it goes without saying that the monitor lamp for controlling the working depth is turned on during the above-mentioned working depth control), but in this state. Then, it is determined whether or not the "lift arm operation" described later. If YES is determined because it is not “lift arm operation”, it is determined whether the detection value E of the draft detection sensor 9 is smaller than the set value F of the draft setting device 19 (E <F), and it is small. If YES is determined, that is, if the working unit 2 is positioned higher than the set state, an ON command is issued to the lowering solenoid valve 27b to lower the working unit 2. Control will be made. On the other hand, when the determination is NO because the detected value E is large, the detected value E is larger than the set value F (E> F).
When it is determined that the lift arm 5 is large, the lift arm 5 determines whether or not the lift arm 5 is within the range of the working range angle Y with the lower limit position as a reference (the lower limit position is 0 degree). (It can be determined based on the detection value of the arm angle detection sensor 8). Here, when the draft control is performed, the angle Y is a rising angle at which the lift arm 5 rises by a certain angle in order to avoid the overload when it is overloaded, X is an angle from the lower limit position to the upper limit position of the lift arm 5. When Z is set, it is represented by “Y + X≈Z”, and the upper limit angle Z is set to be slightly larger than the angle X + Y (larger by the correction value α).

If YES is determined based on the determination that the lift arm 5 is within the range of the angle Y, the lift arm 5 is further determined.
Determines whether or not the angle X has risen, and if it has risen, the lift arm is stopped and the lift solenoid valves 27a and 27b are turned off. When the above is performed, "lift arm operation" is performed, and at the same time, an ON command is issued to the lift solenoid valve 27a to control the lift arm 5 to be lifted by an angle X. On the other hand, if it is determined that the lift arm 5 is in the upper position beyond the range of the angle Y and is in the range of the angle Y, it is determined to be “NO” in spite of being in the rising control state. The lift arm is stopped "and the lift solenoid valve 27a is controlled to be turned off. Therefore, even if a lift command is issued while the lift arm 5 is located near the upper limit position, Ignoring this means that the lift arm 5 is maintained in a stopped state, and as a result, during draft control in which lift control is performed within the swing range of the lift arm 5, a control command exceeding the upper limit is issued. It is possible to reliably prevent the problem that the pressure oil continues to relieve, and in this state, prompt lowering control is performed when the sensor detection value falls below the set value. Ri, it is possible to perform safe and highly accurate draft control.

[Effects] In short, since the present invention is configured as described above, the switching operation of the drive type switching operation tool
The drive system of the power take-off shaft can be arbitrarily switched between the clutch follow-up drive control that stops following the depression of the traveling clutch pedal and the clutch independent drive control that does not stop. When performing working depth control in the set state of independent drive control,
The work depth control determination means provided in the control unit determines this,
The command from the drive type switching operation tool is ignored, and the control command by the clutch follow-up type drive control is issued.Therefore, it is not necessary to switch the drive type switching operation tool each time. It is possible to reliably prevent the unevenness of the height, and to perform highly accurate work depth control by any driving method.

[Brief description of drawings]

1 shows an embodiment of a drive control switching device for a power take-off shaft in an agricultural tractor according to the present invention. FIG. 1 is an overall side view of the agricultural tractor, and FIG. 2 is a drive type switching operation switch. FIG. 3 is a hydraulic circuit diagram, FIG. 4 is a block circuit diagram of the control system, and FIG.
Fig. 6 is a flow chart of the drive type switching control of the power take-off shaft, Fig. 6 is a flow chart of the expansion / contraction control of the lift rod cylinder, Fig. 7 is a flow chart of the draft control, and Figs. 8A and 8B are lifts. It is an explanatory view of an operation of an arm part. In the figure, 1 is a traveling machine body, 2 is a working unit, 4 is a control unit, 5 is a lift arm, 6 is a power takeoff shaft, 17 is a drive type switching switch, 22 is a safety switch, 24 is a plowing depth control switching switch, Reference numeral 23 is a hydraulic clutch, and 27a and 27b are lifting solenoid valves.

Claims (1)

[Scope of utility model registration request] 1. A power interrupting mechanism provided in a power transmission system to a power take-off shaft, and a drive type switching operation tool for the power take-off shaft,
A clutch follower that connects to the power interrupt mechanism by a control unit that issues a control command to the power interrupt mechanism based on the command from the drive type switching operation tool, and switches the power interrupt mechanism to the disconnected state by following the depression of the traveling clutch pedal. In an agricultural tractor configured to be switchable between a mold drive control and a clutch independent drive control that maintains a continuous state, the control unit is connected to a working depth control switching operation tool of a working unit for ground work. When this is set to work depth control, the command from the drive type switching operation tool, which is called clutch independent drive control, is ignored and the control command is issued by the clutch follow-up drive control. A drive control switching device for a power take-off shaft in an agricultural tractor, which is provided with means.