JP3810339B2 - Tractor lifting control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lift control device for a tractor configured to lift and lower a lift arm for lifting and lowering a work device by a mechanical position control device.
[0002]
[Prior art]
As a tractor equipped with a mechanical position control device, for example, as disclosed in Japanese Patent Application Laid-Open No. 8-256515, a position adjustment shaft linked to a position control valve is manually manually adjusted by a position lever. In addition, it is known that the position adjustment shaft can be adjusted by an electric motor so that the electric motor can be operated based on an operation of a manual up / down switch or an automatic backup switch.
[0003]
Specifically, a bell crank-shaped rotating arm 31 is provided between the spool switching shaft 29 (corresponding to the position adjusting shaft) 29 and the motor arm 40 driven by the electric motor 28, and the motor arm 40 and the rotating arm 31 are arranged. A structure in which the link arm 43 fixedly attached to the switching shaft 29 and the other end of the rotating arm 31 are interlocked and connected by the rod 30 is employed. The rod 30 is loosely inserted into the boss 44 provided at the other end of 31 and a nut 45 is attached to the insertion end of the rod 30 so that only a fixed displacement of the rod 30 can be transmitted to the link arm 43. .
[0004]
[Problems to be solved by the invention]
In the conventional example shown in the above publication, the lift arm 9 can be raised and lowered to an arbitrary height by the lift lever 19, and the lift arm 9 can also be raised and lowered by raising the manual up / down switch. The lift arm 9 can also be automatically moved to the highest position by reverse operation, and the work device can be easily raised and lowered when changing the direction of the aircraft at the shore. Since the rotating arm 31 is interposed to link and connect the link arm 43 of the shaft 29, the number of components is increased, and a space for installing the rotating arm 31 is required, resulting in an increase in size of the structure. It was.
[0005]
The present invention has been made paying attention to such points, and by adding a device to the structure for interlockingly connecting the electric motor and the position adjusting shaft (spool switching shaft in the conventional example), the number of components is reduced. And it aims at providing the raising / lowering control apparatus which can exhibit an expected function compactly.
[0006]
[Means for Solving the Problems]
[Configuration, Action, and Effect of Invention of Claim 1]
[0007]
The invention according to claim 1 is a mechanical type in which a position adjusting shaft and a feedback shaft linked to a position control valve that controls the operation of a lift arm for raising and lowering a work device are respectively coupled to a manually operated position lever and a lift arm. In the tractor elevating control device having an electric motor for operating the position adjusting shaft.
A position arm is attached upward to the position adjusting shaft biased in the downward operation direction, and the position lever is swung while the output shaft of the electric motor is positioned higher than the swing fulcrum of the position lever. A dynamic fulcrum and an output shaft of the electric motor are disposed between the position adjustment shaft and a swing fulcrum of a lift arm disposed behind the position adjustment shaft, and the output shaft of the electric motor and the position in a side view. An operation link linked to the position lever and a drive link linked to a motor arm mounted downward from the output shaft of the electric motor are arranged in front of each other at a height position between the swing fulcrum of the lever. It arranged interlockingly connected with a flexible with two elongated holes provided in said position arm portion toward the operation link or drive Li That any of the links phrase with the flexibility even the movement is moved to the raised operative side beyond the corresponding said slot, are configured to position the arms are abutment displaced in the raised operative direction Features.
[0008]
According to the above configuration, in the normal position control state, the operation link is located at the end of the long hole interchange on the ascending operation side, and when the position lever is operated in the ascending direction, the position arm is operated up via the operation link. The lift arm moves up to a height corresponding to the operation position of the position lever. Also, when the position lever is operated in the downward direction, the position arm biased in the downward operation direction is urged and rotated in the downward operation direction following the operation link, and the lift arm corresponds to the operation position of the position lever. Move down to height. In this operation, the relative movement between the drive link and the position arm is absorbed by the long hole interchange.
[0009]
In addition, when the electric motor is driven in the ascending operation direction by a switch operation or the like with the position lever at an arbitrary operation position, the drive link is moved to the ascending operation side beyond the long hole interchange, and the position arm is driven. The lift arm is pivoted in the ascending operation direction via the link, and the lift arm greatly ascends to a height set as the operation limit of the electric motor. In this operation, the relative movement between the operation link and the position arm is absorbed by the long hole interchange.
[0010]
Here, the long hole for interlockingly connecting the position arm, the operation link and the drive link with flexibility is formed in the position arm .
[0011]
Therefore, according to the first aspect of the present invention, the motor arm attached downward from the output lever of the position lever and the electric motor is provided with a long hole provided in the position arm corresponding to both the links via the operation link and the drive link. A lifting control device that has a small number of parts and a compact configuration that can be linked and linked through the interchange of various types, avoids interference between the operation of the position lever and the electric motor, and can perform its intended function. It became possible to configure.
[0012]
[Configuration, Action, and Effect of Invention of Claim 2]
[0013]
According to a second aspect of the present invention, in the first aspect of the invention, the electric motor is configured to be actuated to the ascending side based on an artificial operation of the ascending operation switch.
[0014]
According to the above configuration, when the lift arm is held at a low working position by the position lever and the work is run, the position arm is rotated in the lifting operation direction by the electric motor by one-touch operation of the lifting operation switch. The lift arm can be preferentially raised greatly.
[0015]
Therefore, according to the invention of claim 2, the working device having the working height can be quickly raised only by a light switch operation, and the above-mentioned effect of the invention of claim 1 is brought about, and the direction of the machine body is changed at the shore. Can be done lightly.
[0016]
[Configuration, Action, and Effect of Invention of Claim 3]
[0017]
According to a third aspect of the present invention, in the first or second aspect of the present invention, the electric motor is configured to be actuated upward based on detection that the travel shift lever has been operated in the reverse range.
[0018]
According to the above configuration, when the travel shift lever is operated to the reverse range, the position arm is rotated in the ascending operation direction by the electric motor, and the lift arm is automatically greatly increased.
[0019]
Therefore, according to the invention of claim 3, while providing the above-mentioned effect of the invention of claim 1 or 2, it is possible to perform the backup control using the electric motor, and to avoid the damage of the working device at the time of reverse driving at the end. can do.
[0020]
[Configuration, Action, and Effect of Invention of Claim 4]
[0021]
The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the position lever corresponds to the height of the lift arm in a state where the position arm is operated to the ascending operation side by the electric motor. A means for detecting that the operation position has been operated is provided, and a control means for returning the electric motor to the lowering operation side based on the detection is provided.
[0022]
According to the above configuration, when the position switch is operated to the operation position corresponding to the height of the lift arm after the ascent operation switch or the reverse switch is operated and the position arm is operated to the ascending operation side by the electric motor, this is detected. Thus, the electric motor returns to the lowering operation side. In this case, the position arm is supported by the operation link at the rotation position corresponding to the position lever and held at that position, and is restored to the normal mechanical position control state. That is, after that, the lift arm can be arbitrarily raised and lowered to a height corresponding to the operation position of the position lever.
[0023]
Therefore, according to the invention of claim 4, after the electric motor is operated in accordance with an electrical command and the lift arm is preferentially raised, the original mechanical position control state is simply restored by operating the position lever. It is possible to achieve the above-mentioned effects of the invention according to any one of claims 1 to 3, and the handleability is excellent.
[0024]
[Configuration, Action, and Effect of Invention of Claim 5]
[0025]
According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, a stopper is provided for restricting the operation limit of the electric motor to the ascending operation side and the descending operation side. The motor driving is automatically stopped based on the increase of the motor driving current due to the contact.
[0026]
According to the above configuration, the electric motor is operated to a predetermined limit without electrically detecting the operation limit of the electric motor to the upward operation side and the downward operation side using sensors such as a limit switch and a potentiometer. Thus, the energization drive can be stopped accurately, and the above effect of the invention according to any one of claims 1 to 4 can be achieved, and the automatic motor stop structure at the operation limit can be configured at low cost.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a rear right side surface of a tractor configured to have a rotary tillage specification. In this tractor, a rotary tiller device 3 as an example of a working device is connected to a three-point link mechanism 2 provided at the rear portion of the tractor main unit 1, and a pair of left and right lift arms 4 swinging up and down by hydraulic drive are used for the three tractors. The point link mechanism 2 is driven up and down, and a single-acting lift cylinder 5 (see FIG. 5) that integrally swings and drives the left and right lift arms 4 is provided for the transmission case 6 in the tractor main unit 1. It is housed in a cylinder case 7 connected to the upper part.
[0028]
As shown in the control hydraulic circuit in FIG. 8, the lift cylinder 5 is controlled by a position control valve 10, which includes a main spool 11, a lowering valve 12, a relief valve. 13, an unload valve 14, etc., and the lift cylinder 5 and the position control valve 10 are connected via a drop speed adjusting valve 15.
[0029]
The position control valve 10 is connected to and supported by the lower surface of the cylinder case 7, and a connection link 16 is pivotally connected to the end of the main spool 11 so that the balance can swing. The connected position adjusting shaft 17 and feedback shaft 18 are provided through the right and left sides of the cylinder case 7 so as to penetrate horizontally.
[0030]
A position arm 19 is fixed to the outer end portion of the position adjusting shaft 17, and the outer end portion of the feedback shaft 18 and the left lift arm 4 are interlocked and connected via a feedback link 20. As a result, the connecting link 16 swings around the end on the feedback side, the main spool 11 is shifted to the ascending side U or the descending side D, and the lift arm 4 is driven and lifted via the lift cylinder 5. Or the dead weight lowering operation is performed. When the lift arm 4 is operated, the operation is converted into the rotation of the feedback shaft 18 through the feedback link 20, the main spool 11 is shifted in the reverse direction through the connection link 16, and the position adjustment shaft 17 is rotated. When the feedback shaft 18 is rotated to a predetermined rotation position corresponding to the operation position, the main spool 11 returns to neutral, and the lifting operation is stopped. That is, a position control mechanism is configured to raise and lower the lift arm 4 to a position corresponding to the position arm 19 by arbitrarily rotating the position arm 19.
[0031]
As shown in FIG. 2, a driver's seat 8 is provided above the cylinder case 7, and a position lever 22 for artificially setting a work height is provided on the right side of the driver seat 8 with the position adjusting shaft 17. An operation link that is disposed so as to be able to swing back and forth around the fulcrum a and to be able to hold friction at an arbitrary operation position at a position corresponding to the lift arm fulcrum, and is pivotally extended forward from the position lever 22 The front end of 23 is engaged and connected to a long hole 24 formed in the position arm 19 with flexibility.
[0032]
The main spool 11 of the position control valve 10 is always urged to the lowering side D by the spring 25, and the position arm 19 is always urged to rotate clockwise in FIGS. The rear end of the long hole 24 is in contact with the front end of the operation link 23. Therefore, as the position lever 22 swings backward (counterclockwise in FIG. 2), the position arm 19 engaged and supported by the operation link 23 moves backward (in FIG. 2) against the urging force. And the lift arm 4 is raised to a position corresponding to the operation position of the position arm 19. On the contrary, as the position lever 22 swings forward (clockwise in FIG. 2), the position arm 19 that is urged to rotate follows the position lever 22 and rotates forward. The lift arm 4 is lowered to a position corresponding to the operation position of the position arm 19. In the state in which the position lever 22 is operated to the foremost position, the position control valve 10 is maintained in the lowered state without being returned to neutral regardless of the feedback accompanying the lowering of the lift arm 4. Thus, a state in which the lift arm 4 can be lowered by its own weight to a mechanical lower limit, that is, a so-called floating state is brought about.
[0033]
The position control mechanism is not particularly different from the conventional one. In the present invention, the following configuration is further added.
[0034]
That is, as shown in FIG. 6, an electric motor 32 with a speed reducer is provided on the right side surface of the cylinder case 7 via a bracket 31, and a motor arm 33 is mounted on a speed reduction output shaft 32 a of the electric motor 32. Is connected and fixed, and the front end portion of the drive link 34 pivotally extended from the free end portion of the motor arm 33 is engaged and connected to a long hole 35 formed in the position arm 19 with flexibility.
[0035]
As shown in FIG. 9, the control device 36 for controlling the operation of the electric motor 32 includes an ascending operation switch 37, a descending operation switch 38, a driving device disposed at appropriate positions such as the right lateral side of the driver seat 8 or the front panel. The reverse switch 40 that detects that the travel shift lever 39 provided on the left side of the seat 8 is operated to the reverse range, and the upper limit that is pressed when the position lever 22 is operated to the highest position. The detection switches 41 are connected to each other, and the electric motor 32 is controlled to perform forward / reverse operation as follows according to the operation of these switches. Note that the rotation limit of the motor arm 33 is regulated by contact with a pair of stoppers 42 and 43 attached to the bracket 31. As shown in FIG. 7, the upper limit detection switch 41 is mounted on the side surface of the rear wheel fender 44 via a bracket 45 and is pressed by an operation piece 46 attached to the position lever 22. .
[0036]
Normally, the motor arm 33 is in a position that is abutted and supported by a stopper 42 that restricts the counterclockwise rotation limit. At this time, since the drive link 34 is moved forward, the position arm 19 is driven. The rotation of the link 34 is not limited, and the link 34 swings and displaces following the operation of the position lever 22.
[0037]
FIG. 2 shows a state where the position lever 22 is operated to a low position and the position control is stably maintained in a neutral state. When the raising operation switch 37 is operated in this state, the electric motor 32 is energized and the motor arm 33 is driven. Rotates clockwise and the drive link 34 is pulled backward. The front end portion of the drive link 34 moves rearward along the long hole 35, and the position arm 19 moves upward in the counterclockwise direction U by the further rearward movement of the drive link 34 after reaching the rear end of the long hole 35. This lifts the lift arm 4 upward.
[0038]
As shown in FIG. 3, when the motor arm 33 comes into contact with the stopper 43 and is prevented from rotating further in the clockwise direction, an excessive current flows through the electric motor 32, which is generated in the control device. And the power supply to the electric motor 32 is automatically cut off. As the motor arm 33 is rotated to the upper limit in this way, the lift arm 4 is driven to the highest position or a high position close thereto, and the rotary tiller 3 is greatly raised.
[0039]
In addition, when the travel shift lever 39 is operated from the forward range or the neutral position to the reverse range, this is detected by the reverse switch 40, and the electric motor 32 is rotated clockwise to rotate the rotary tiller 3 as described above. Control that is greatly increased, so-called backup control is executed.
[0040]
When the lowering operation switch 38 is operated from the state of FIG. 3 in which the lift arm 4 is raised, the electric motor 32 is energized in the reverse direction and rotated counterclockwise until the motor arm 33 contacts the stopper 42. When the rotation of the motor arm 33 is prevented and an overcurrent flows through the electric motor 32, this is detected and the energization of the electric motor 32 is automatically cut off as described above. Thus, when the motor arm 33 rotates counterclockwise and the drive link 34 is pushed forward, the position arm 19 that is urged to swing follows the forward movement of the drive link 34 in the downward direction D. It swings and the lift arm 4 descends. When the rear end of the long hole 24 of the position arm 19 is received by the front end portion of the operation link 23, the position arm 19 can no longer swing in the descending direction D, and only the drive link 34 has the long hole 35. Move forward along. In other words, the rotary tiller 3 can be lowered to the original height set by the position lever 22 by operating the lower operation switch 38 after raising the rotary tiller 3 with the raising operation switch 37.
[0041]
Accordingly, when the direction of the body is changed at the end of the first-plow tillage, the rotary tiller 3 can be greatly raised only by lightly operating the raising operation switch 37 one-shot. Therefore, the rotary tiller 3 can be lowered to the original height simply by lightly operating the lowering operation switch 38 after the direction change.
[0042]
Further, when maneuvering the aircraft on the coast, if the reverse operation is performed to perform a switch turn or the like, the rotary tiller 3 is automatically raised greatly by the above-described backup control, and the rotary tiller 3 is lowered. It is avoided in advance that the vehicle will move backward and hit the bag.
[0043]
In addition, as shown in FIG. 4, when the position lever 22 is operated to the highest position in the state in which the rotary tiller 3 is greatly raised by operating the raising operation switch 37, the upper limit detection switch 41 is operated and the electric operation is performed. The motor 32 is rotated in the reverse direction, and is rotated counterclockwise until the motor arm 33 contacts the stopper 42 as shown in FIG. In this case, since the operation link 23 is engaged with the rear end of the long hole 24, the position arm 19 does not swing, and only the drive link 34 moves forward along the long hole 35.
[0044]
Thereafter, when the position lever 22 is operated in the descending direction, the position arm 19 also follows and swings in the descending direction D as the operation link 23 moves forward, and the lift arm 4 moves to a height corresponding to the operating position of the position lever 22. Moving. That is, after operating the raising operation switch 37 to raise the rotary tiller 3 greatly, the position lever 22 is operated to the highest position to restore the normal mechanical position control mode.
[0045]
[Another embodiment]
The present invention can also be implemented in the following forms.
[0046]
(1) Instead of a mode in which the electric motor 32 is driven in the forward / reverse direction by the ascending operation switch 37 and the lowering operation switch 38, a mode in which the electric motor 32 is repeatedly driven in the forward / reverse direction each time a single switch is operated. Can also be adopted. In this case, it is convenient to use a built-in pushbutton switch with a lamp so that the lamp is turned on by the raising operation and turned off by the next lowering operation so that the switch operation state can be easily recognized.
[0047]
(2) As a means for detecting that the travel shift lever 39 has been operated to the reverse range, or a means for detecting that the position lever 22 has been operated to the highest position, in addition to using a limit switch, A switch, an optical sensor, or the like can also be used.
[Brief description of the drawings]
[Fig. 1] Right side view of the rear of the tractor [Fig. 2] Side view of the valve operating unit [Fig. 3] Side view of the valve operating unit [Fig. 4] Side view of the valve operating unit [Fig. 5] Side view of the valve operating unit [Fig. 6] Plan view of valve operation unit [Fig. 7] Plan view of upper limit detection switch operation structure [Fig. 8] Hydraulic circuit diagram [Fig. 9] Control block diagram [Explanation of symbols]
4 Lift Arm 10 Position Control Valve 17 Position Adjustment Shaft 18 Feedback Shaft 19 Position Arm 22 Position Lever 23 Operation Link 24 Long Hole 32 Electric Motor 34 Drive Link 35 Long Hole 37 Lifting Operation Switch 39 Traveling Shift Lever 42 Stopper 43 Stopper

Claims (5)

The position adjustment shaft and the feedback shaft linked to the position control valve that controls the lift arm for raising and lowering the work device are linked to the manually operated position lever and lift arm to form a mechanical position control mechanism. In the tractor lift control device including an electric motor for operating the position adjusting shaft,
A position arm is attached upward to the position adjustment shaft biased in the downward operation direction, and the position lever is swung while the output shaft of the electric motor is positioned higher than the swing fulcrum of the position lever. A dynamic fulcrum and an output shaft of the electric motor are disposed between the position adjustment shaft and a swing fulcrum of a lift arm disposed behind the position adjustment shaft, and the output shaft of the electric motor and the position in a side view. An operation link linked to the position lever and a drive link linked to a motor arm mounted downward from the output shaft of the electric motor are arranged in front of each other at a height position between the swing fulcrum of the lever. It arranged interlockingly connected with a flexible with two elongated holes provided in said position arm portion toward the operation link or drive Li That any of the links phrase with the flexibility even the movement is moved to the raised operative side beyond the corresponding said slot, are configured to position the arms are abutment displaced in the raised operative direction Characteristic tractor lifting control device.   The tractor elevating control device according to claim 1, wherein the electric motor is configured to be operated to an ascending operation side based on an artificial operation of an ascending operation switch.   The tractor lift control device according to claim 1 or 2, wherein the electric motor is configured to be operated to the ascending operation side based on detection that the travel shift lever is operated in the reverse range.   The electric motor includes means for detecting that the position lever has been operated to the operation position corresponding to the height of the lift arm in a state where the position arm is operated to the ascending operation side by the electric motor. The tractor elevating control device according to any one of claims 1 to 3, further comprising control means for returning to the lowering operation side.   A stopper is provided for restricting the contact of the electric motor to the ascending operation side and the descending operation side, and the motor drive is automatically stopped based on the increase in motor drive current due to contact with the stopper. The raising / lowering control apparatus of the tractor as described in any one of Claims 1-4.

Images