JPH06337004A - Hydraulic actuator operating structure of working vehicle - Google Patents

Abstract

PURPOSE:To reduce a dispersion of stop state of a working device when an operating lever is returned to the neutral stop position. CONSTITUTION:A hydraulic actuator operating structure of a working vehicle is provided with a speed sensor for detecting the operating speed of a working device, whereby when an operating lever 24 is operated to the neutral stop position N, if the working device is decelerated to a designated low speed, an operating current of an electromagnetic proportional valve 19 is held to an operating current corresponding to the designated low speed, and after that, the working device is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic proportional valve capable of controlling a flow rate for supplying and discharging working oil to a hydraulic actuator for driving a working device provided in a machine body, and for operating the electromagnetic proportional valve. The present invention relates to a hydraulic actuator operating structure for a work vehicle that includes an artificial operating tool (an operating lever, an operating pedal, etc.) that is operated manually.

[0002]

2. Description of the Related Art An example of a hydraulic actuator operating structure for a work vehicle as described above is disclosed in Japanese Patent Application Laid-Open No. 2-256901. With this configuration,
Hydraulic motor for turning drive (13 in FIG. 1 of the above publication)
(Corresponding to a hydraulic actuator), an electromagnetic proportional valve (3 in FIG. 1 of the publication) capable of controlling the flow rate by operating and supplying hydraulic oil from a pump to operate the hydraulic motor, and an operation lever (first of the publication). 14) in the figure (corresponding to a manual operation tool) and a position sensor (18 in FIG. 1 of the above publication) for detecting the operation position of the operation lever.

As a result, when the operating lever is operated to the neutral stop position as shown in FIG. 2 of the publication based on the detected value of the position sensor, the solenoid proportional valve is operated to the neutral position and the hydraulic motor operates. It has stopped. When the operation lever is operated from the neutral stop position to the operation position side, the operation current is passed through the solenoid proportional valve so that the flow rate of the hydraulic oil from the solenoid proportional valve increases as the operation amount increases.
The solenoid proportional valve is operated from the neutral position to the hydraulic oil supply position side. As described above, the larger the operating lever is operated from the neutral stop position, the faster the hydraulic motor operates, and the operating position of the operating lever allows the hydraulic motor to operate at a desired operating speed.

[0004]

It is assumed that the operation lever is returned to the neutral stop position side in a state where the operation lever is operated to a certain operation position and the hydraulic motor is operated in the above-mentioned configuration. In this case, the solenoid proportional valve is also operated to the neutral position side in response to the return operation of the operation lever, and when the operation lever is operated to the neutral stop position, the solenoid proportional valve is also operated to the neutral position and the hydraulic motor is stopped. Will be done.

However, when a large load or inertia is applied to the hydraulic motor (in the case of the backhoe disclosed in the above publication, for example, a large amount of soil is put in the bucket of the backhoe provided on the swivel base, , The backhoe device is greatly extended forward, etc.), or the flow rate of the hydraulic oil supplied from the solenoid proportional valve to the hydraulic motor is changing, the operation lever is operated to the neutral stop position and the electromagnetic When the proportional valve is also operated to the neutral position, the hydraulic motor may suddenly stop, or may stop before the desired stop position, such that the stopped state may vary. It is an object of the present invention to configure the hydraulic actuator so that it can be stopped in a constant state as much as possible without being affected by the load and inertia applied to the hydraulic actuator, and changes in the flow rate of hydraulic oil.

[0006]

A feature of the present invention is that the hydraulic actuator operating structure for a work vehicle as described above is configured as follows. That is, [1] A hydraulic actuator for driving a working device provided in the machine body is operated artificially with a flow-controllable solenoid proportional valve that operates by supplying and discharging hydraulic oil from a pump. Equipped with a manual operation tool and a position sensor that detects the operation position of the manual operation tool, and based on the detection value of the position sensor, when the manual operation tool is operated to the neutral stop position, the solenoid proportional valve is set to the neutral position. In response to the operation amount of the manual operation tool operated from the neutral stop position to the operation position side, the solenoid proportional valve is adjusted so that the flow rate of the hydraulic oil from the solenoid proportional valve increases as the operation amount increases. It is equipped with a control means for passing an operating current to operate it from the neutral position to the hydraulic oil supply position side, and with a speed sensor for detecting the operating speed of the working device, so that the human operating tool moves from the operating position to the neutral stop position. operation When the detected value of the speed sensor reaches a predetermined low speed, the holding means holds the operation current output from the control means at the operation current corresponding to the predetermined low speed.

[2] The operation of the working device detected by the speed sensor in the state of the operation of the solenoid proportional valve having the operation current corresponding to a predetermined low speed by the holding means in the structure of the above [1]. When the speed falls below a predetermined low speed, the solenoid proportional valve is operated to increase the flow rate,
The changing means for changing the operating current to the solenoid proportional valve is provided.

[0008]

[Action]

[I] With the configuration as described in [1] above, as shown in the dashed-dotted line A2 in FIG. Is operated, the operating speed of the work device is also reduced.
After that, when the operating speed of the work device reaches a predetermined low speed, the operation current to the solenoid proportional valve 19 is the operation current I1 corresponding to the predetermined low speed at this time, irrespective of the operation position of the manual operation tool 24. Therefore, when the manual operation tool 24 reaches the neutral stop position N, the solenoid proportional valve 19 is also operated to the neutral position and the working device is also stopped.

In this case, if the operating speed of the working device is reduced to a predetermined low speed, regardless of the inertia and load of the working device, the flow rate of hydraulic oil supplied from the pump, etc. , The electromagnetic proportional valve is held in a state corresponding to this predetermined low speed. As a result, the operating speed of the working device is maintained at the above-mentioned predetermined low speed to some extent, and then the operation is stopped.Therefore, the stopped state of the working device is kept constant regardless of various states. Can be set.

[II] For example, when a particularly heavy load is applied to the working device, the manipulator is operated to the neutral stop position side so that the operating current to the solenoid proportional valve becomes a predetermined low speed at this time. When the operating current is maintained at the corresponding operating current, the operating speed of the work device may be greatly reduced from the above-mentioned predetermined low speed due to a large load, and the work device may stop before the desired stop position. is there. Therefore, the previous section [2]
With such a configuration, when the operating speed of the working device becomes lower than the predetermined low speed described above, the solenoid proportional valve is operated to the flow rate increasing side, and the decrease in the operating speed of the working device is suppressed.

[0011]

As described above, when the artificial operating tool is returned to the neutral stop position, the solenoid proportional valve is not operated so as to simply follow the returning operation, but the predetermined operation is performed as in claim 1. By temporarily holding the solenoid proportional valve in a state corresponding to low speed, it has become possible to set the stopped state of the working device to a constant one regardless of various states. As a result, it becomes possible to stabilize the work device during the stop operation.

According to the second aspect of the invention, when the solenoid proportional valve is temporarily held in a state corresponding to a predetermined low speed, the work device is stopped by a large load before the desired stop position. Since such a situation can also be prevented, it is possible to further stabilize the work device during the stop operation.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. (1) As shown in FIG. 1, a pair of left and right front wheels 1 and rear wheels 2
An agricultural tractor, which is an example of a work vehicle, is provided with an engine 3, a control unit 4 at the center, and a mission case 5 at the rear of the machine body supported by the dozer device 6, and the machine body at the front of the machine body. A backhoe device 7 (corresponding to a working device) is provided as an attachment at the rear part.

Next, the backhoe device 7 will be described. As shown in FIG. 1, a support portion 8 connected to the rear portion of the mission case 5 is rocked around a vertical axis P1 of the support portion 8 by a pair of left and right hydraulic cylinders 9 and 10 (corresponding to hydraulic actuators). A swing bracket 11, a boom 12 swingably operated around a horizontal axis P2 of the swing bracket 11 by a hydraulic cylinder 15, and an arm 13 swingably operated around a horizontal axis P3 at the tip of the boom 12 by a hydraulic cylinder 16. , A bucket 14 swinging around a horizontal axis P4 at the tip of the arm 13 by a hydraulic cylinder 17, a pair of left and right outriggers 33 moving up and down by a hydraulic cylinder 34, and a steering fixed to the support portion 8. The backhoe device 7 is configured by the portion 18 and the like.

(2) Next, the operation structure of the backhoe device 7 will be described. As shown in FIG. 3, a solenoid proportional valve 19 for the pair of hydraulic cylinders 9 and 10 for the swing bracket 11, a control valve 20 for the hydraulic cylinder 15 for the boom 12, a pair of control valves 35 for the hydraulic cylinder 34 for the outrigger 33, Hydraulic cylinder 1 for arm 13
6 and a control valve 22 for the hydraulic cylinder 17 for the bucket 14 are provided. The solenoid proportional valve 19 is a center bypass type and a neutral return type.
The control valves 20, 21, 22, 35 are center bypass type and mechanically operated. The electromagnetic proportional valve 19 and the control valves 20, 21, 22, 35 are connected to the pump 25 in parallel.

As shown in FIGS. 1 and 3, a right operating lever 2 which can be operated in the front, rear, left and right directions on a control portion 18 of the backhoe device 7.
3 and a left operation lever 24 (corresponding to an artificial operation tool) are provided, and a right operation lever 23 and a control valve 2 for the boom 12 are provided.
0 and the control valve 22 for the bucket 14 are mechanically interlocked. Thereby, when the right operation lever 23 is operated back and forth, the control valve 20 is switched and the boom 12 is rocked, and when the right operation lever 23 is operated left and right, the control valve 22 is switched and operated. The bucket 14 is rocked.

The left operating lever 24 and the control valve 21 for the arm 13 are mechanically linked to each other, and the left operating lever 2
When 4 is operated back and forth, the control valve 21 is switched and the arm 13 is rocked. A position sensor 26 for detecting the left-right operation position of the left operation lever 24 is provided, and the detection value of the position sensor 26 is input to the control device 27 (corresponding to control means). When the left operation lever 24 is operated to the left or right, based on the detection value of the position sensor 26,
The solenoid proportional valve 19 is operated by the operation current from the control device 27, and the swing bracket 11 is rocked right and left.

(3) Next, the operation of the swing bracket 11 in the backhoe device 7 will be described. Figure 2
As shown in (a) and FIG. 1, a swing bracket 11 is swingably supported left and right around a vertical axis P1 of a supporting portion 8 of the backhoe device 7, and a pair of left and right sides sandwiching the vertical axis P1 is provided. Double-acting hydraulic cylinders 9 and 10 are connected to a swing bracket 11. As shown in FIGS. 2A and 3, a pair of oil passages 28, 29 from the solenoid proportional valve 19 is provided.
One of the oil passages 28 is connected in parallel to the extension-side oil chamber 9 a of the one hydraulic cylinder 9 and the contraction-side oil chamber 10 b of the other hydraulic cylinder 10, and the other oil passage 29.
Is connected in parallel to the contraction side oil chamber 9b of one hydraulic cylinder 9 and the expansion side oil chamber 10a of the other hydraulic cylinder 10.

The state shown in FIG. 2 (a) is a state in which the swing bracket 11 is located at the center of the left and right. When hydraulic oil is supplied from the electromagnetic proportional valve 19 to the oil passage 28 from this state, for example, one hydraulic cylinder 9 begins to expand and the other hydraulic cylinder 10 begins to contract, and the swing bracket 1
1 starts swinging to the left.

Then, as shown in FIG. 2B, when one hydraulic cylinder 9 reaches the vertical axis P1, the hydraulic cylinder 9 extends near the stroke end. As a result, due to the contracting action of the other hydraulic cylinder 10, the hydraulic oil discharged from the expansion-side oil chamber 10a of the hydraulic cylinder 10 is supplied to the contraction-side oil chamber 9b of the hydraulic cylinder 9, and the hydraulic cylinder 9 is contracted. Also shrinks, Figure 2
As shown in (c), the swing bracket 11 reaches the left swing end. The above state also occurs when swinging the swing bracket 11 to the right.

(4) Next, the control of the hydraulic cylinders 9 and 10 for the swing bracket 11 by the left operating lever 24 will be described. (4) -1 The detection value of the position sensor 26 that detects the left and right operation positions of the left operation lever 24 and the operation current to the solenoid proportional valve 19 for the hydraulic cylinders 9 and 10 are shown in FIG.
The relationship is set as shown by the solid line A1.

As a result, when the left operation lever 24 is operated to the neutral stop position N, the operation current to the solenoid proportional valve 19 is set to zero and the solenoid proportional valve 19 is operated to its neutral position by its neutral return action. The hydraulic cylinders 9 and 10 are stopped. Next, when the left operation lever 24 is operated from the neutral stop position N to the right swing position R (corresponding to the operating position) or the left swing position L (corresponding to the operating position), the neutral stop position N is moved to the right or Corresponding to the operation amount of the left operation lever 24 to the left swing position R, L side, the flow rate of the hydraulic oil from the solenoid proportional valve 19 increases as the operation amount increases, so The operating current is set to be large.

The inclination of the first half on the neutral stop position N side of the solid line A1 is set gently, and the inclination of the latter half on the right or left swing position R, L side is set large. As a result, in the first half on the neutral stop position N side where the hydraulic cylinders 9 and 10 operate at a relatively low speed, the left operation lever 24 can be used to make a subtle speed change.

(4) -2 Next, a case will be described in which the left operation lever 24 is returned to the neutral stop position N from a state where it is operated to the right or left swing position R, L side operation position. As shown in FIG. 2A and FIG. 3, a potentiometer 30 (corresponding to a speed sensor) that detects the position of the swing bracket 11 is provided, and the detected value of the potentiometer 30 is differentiated to differentiate the swing bracket 11 from the swing bracket 11. The swing speed is detected.

The left operating lever 24 is moved to the right or left swing position R,
It is assumed that the swing bracket 11 is moved to the operation position on the L side and is swinging at a certain swing speed. From this state,
When the left operation lever 24 is returned to the neutral stop position N side as shown by the alternate long and short dash line A2, the operation current of the solenoid proportional valve 19 is also reduced, and along with this, the swing bracket 1
The rocking speed of 1 also decreases.

When the swing speed of the swing bracket 11 reaches a predetermined low speed in a state where the left operation lever 24 reaches a position just before the neutral stop position N, the alternate long and short dash line A in FIG.
As shown in 2, regardless of the operation position of the left operation lever 24, the operation current to the solenoid proportional valve 19 is held at the operation current I2 corresponding to the predetermined low speed at this time (corresponding to the holding means). After that, when the left operation lever 24 reaches the neutral stop position N, the operation current to the solenoid proportional valve 19 is reduced to zero and the swing bracket 11 stops.

In this structure, when a large amount of soil is put in the bucket 14 of the backhoe device 7, or when the boom 12 and the arm 13 of the backhoe device 7 are largely extended rearward, the rotational speed of the engine 3 is high and the pump is high. When the flow rate of the hydraulic oil supplied from 25 to the solenoid proportional valve 19 is large, the backhoe device 7 itself has a large inertia when the swing bracket 11 is being rocked.

Therefore, when the left operation lever 24 is operated to the neutral stop position N side in this state, the swing bracket 1
Since the rocking speed of No. 1 does not immediately decrease, the rocking speed of the swing bracket 11 is set to a predetermined value at the operation position closer to the neutral stop position N than the operation position of the left operation lever 24 corresponding to the operation current I2 in FIG. Reach a low speed. As a result, the operation current to the solenoid proportional valve 19 is held at the operation current I1 (lower than the above-mentioned operation current I2) corresponding to the predetermined low speed at this time (corresponding to the holding means), and the left operation is performed. When the lever 24 reaches the neutral stop position N, the operating current to the solenoid proportional valve 19 is reduced to zero and the swing bracket 11 stops.

On the contrary, in this configuration, the backhoe device 7
When nothing is put in the bucket 14 of the engine, or when the boom 12 and the arm 13 of the backhoe device 7 are folded to the body side, the rotation speed of the engine 3 is low and the pump 2
When the flow rate of the hydraulic oil supplied from 5 to the solenoid proportional valve 19 is small, the backhoe device 7 itself does not have a large inertia during the swing operation of the swing bracket 11.

Therefore, when the left operation lever 24 is operated to the neutral stop position N side in this state, the swing bracket 1
Since the rocking speed of 1 immediately decreases, the operating current I in FIG.
At the operating position before the operating position of the left operating lever 24 corresponding to 2, the swing speed of the swing bracket 11 reaches a predetermined low speed. As a result, the solenoid proportional valve 19
The operating current to the motor is held at the operating current I3 (higher than the operating current I2 described above) corresponding to the predetermined low speed at this time (corresponding to the holding means), and the left operating lever 24 is in the neutral stop position N. When, the operating current to the solenoid proportional valve 19 is dropped to zero and the swing bracket 11 stops.

(4) -3 For example, when the swing bracket 11 is rocked to move the soil on the side of the bucket 14 to one side, a large load is applied to the rocking operation of the swing bracket 11. Will be applied. In such a case, with the configuration of (4) -2 above, as shown by the alternate long and short dash line A3 in FIG. 5, the left operation lever 24 is operated to the neutral stop position N side to operate the solenoid proportional valve 19. When the current is held at the operation current I4 corresponding to the predetermined low speed at this time, the swing bracket 1 is caused by a large load applied to the bucket 14.
In some cases, the swing speed of No. 1 is greatly reduced from the above-described predetermined low speed, and the swing bracket 11 stops before the desired stop position.

In such a case, if the swing speed of the swing bracket 11 detected by the potentiometer 30 becomes lower than the predetermined low speed, the one-dot chain line A in FIG.
As shown in FIG. 3, the held operating current I4 is slightly increased and the solenoid proportional valve 19 is operated to the flow rate increasing side, and the deceleration of the swing speed of the swing bracket 11 is suppressed. When the swing speed of the swing bracket 11 returns to the above-mentioned predetermined low speed, the operation current I5 at that time is returned.
Is held in.

[Other Embodiments] The present invention can be applied not only to the swing bracket 11 of the backhoe device 7 but also to the boom 12 and the arm 13 of the backhoe device 7. The present invention can be applied not only to the backhoe device 7 but also to the dozer device 6 and other working devices.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is an overall side view of an agricultural tractor, a dozer device, and a backhoe device.

FIG. 2 is a plan view showing each swinging state of the swing bracket of the backhoe device.

FIG. 3 is a hydraulic circuit diagram of a backhoe device.

FIG. 4 shows the relationship between the operation position of the left operation lever and the operation current to the solenoid proportional valve, and operates the left operation lever to the neutral stop position side to keep the operation current at a value corresponding to a predetermined low speed. Figure showing the broken state

FIG. 5 shows the relationship between the operating position of the left operating lever and the operating current to the solenoid proportional valve. When the operating current is maintained by operating the left operating lever toward the neutral stop position, the backhoe device decelerates. Figure showing a state where the operating current has been increased again after passing

[Explanation of symbols]

 7 Working device 9, 10 Hydraulic actuator 19 Electromagnetic proportional valve 24 Manual operation tool 25 Pump 26 Position sensor 27 Control means 30 Speed sensor N Neutral stop position of manual operation tool R, L Operating position of manual operation tool I1, I2, I3 I4 operating current

Claims (2)

[Claims] 1. A pump (2) is attached to a hydraulic actuator (9), (10) for driving a working device (7) provided in the machine body.
5) An electromagnetic proportional valve (19) capable of controlling the flow rate by operating and supplying the hydraulic oil from the hydraulic oil, operating it, an artificial operation tool (24) artificially operated, and the artificial operation tool (24) And a position sensor (26) for detecting the operation position of the position sensor (26), and based on the detection value of the position sensor (26), the human operation tool (24) is operated to the neutral stop position (N). The solenoid proportional valve (19) is operated to the neutral position, and in accordance with the operation amount of the artificial operation tool (24) from the neutral stop position (N) to the operation positions (R) and (L), In order that the flow rate of the hydraulic oil from the solenoid proportional valve (19) increases as the operation amount increases, the solenoid proportional valve (1
9) is provided with a control means (27) for applying an operation current to operate the operation current from the neutral position to the hydraulic oil supply position side, and also with a speed sensor (30) for detecting the operation speed of the working device (7). Then, when the artificial operation tool (24) is operated from the operating positions (R) and (L) to the neutral stop position (N), the detection value of the speed sensor (30) reaches a predetermined low speed. , The operation current output from the control means (27) is the operation current (I1) corresponding to the predetermined low speed,
(I2), (I3), (I4) A hydraulic actuator operating structure for a work vehicle, which is provided with a holding means. 2. The solenoid proportional valve (1
Work detected by the speed sensor (30) while the operation current to 9) is held at the operation currents (I1), (I2), (I3), and (I4) corresponding to the predetermined low speed. When the operating speed of the device (7) becomes lower than the predetermined low speed, the operation current to the solenoid proportional valve (19) is changed so that the solenoid proportional valve (19) is operated to increase the flow rate. The hydraulic actuator operating structure for a work vehicle according to claim 1, further comprising: