JPH079Y2 - Lifting control valve structure of working part - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a lifting control valve structure of a working unit assembled to a working vehicle such as an agricultural tractor, a riding type rice transplanter, or a combine.

[Problems to be Solved by Prior Art and Invention] Generally, in this type of work vehicle, the lifting / lowering control of a working unit mounted on a traveling machine body is performed by hydraulic control based on expansion / contraction of a hydraulic cylinder. ing. In this case, when the working unit is lifted up and down close to the set position, it is necessary to reduce the speed to reduce the shock at the time of stop and to perform deceleration control so that the work unit can be stopped accurately at the set position. For this reason, conventionally, the control valve device has been provided with a throttle mechanism that throttles the amount of pressure oil supplied to the hydraulic cylinder side when set in the ascending / descending speed deceleration control state to perform the deceleration control. By the way, the throttle mechanism is required to be highly accurate in its nature, but the control valve device has various basic mechanisms such as a valve mechanism for switching the working unit between rising, neutral and lowering. However, in order to provide the above-mentioned throttle mechanism so as not to affect them, the control valve device is complicated and complicated, and it is practically impossible to adjust the throttle amount. Therefore, there is a possibility that required deceleration control may not be obtained, resulting in lack of reliability. Moreover, the throttle mechanism is often set specifically for that model, so if it is provided in a control valve device, that control valve device can no longer be used as a control valve device of another model. Therefore, there is a problem in terms of versatility of the control valve device.

[Means for Solving the Problem] The present invention has been made in view of the above circumstances and was devised for the purpose of providing a lifting control valve structure for a working unit capable of eliminating these drawbacks. A control valve device for controlling expansion and contraction of a hydraulic cylinder for lifting and lowering a part is provided with a pump side oil passage for supplying pressure oil from a hydraulic pump to a pump port of the control valve device and a pressure oil from a cylinder port of the control valve device. The cylinder side oil passage for supplying to the hydraulic cylinder side is integrally assembled to the respective hydraulic housings, and the control valve device is provided with a pressure oil from the pump port when set in the ascending / descending speed deceleration control state. While the valve lock mechanism that locks the supply is installed, the hydraulic housing receives the pressure oil in the locked state and throttles it from the oil passage on the pump side to the oil passage on the cylinder side. It is characterized in that a bypass oil passage with a throttle mechanism for supplying pressure oil is provided.

According to this configuration, the present invention provides the throttle mechanism for deceleration control independently of the control valve device to improve the reliability thereof, and also enables the control valve device to be widely used. It is a thing.

[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 working unit 3 is attached to a rear portion of the traveling machine body 1 via an elevating link mechanism 2, and the working unit 3 is a lift arm 4. It is the same as the conventional one that it can be moved up and down by vertical swing.

The lift arm cylinder 5 that controls the vertical swing of the lift arm 4 receives pressure oil from the hydraulic pump 6 and expands and contracts. A control valve (control valve device) 7 that controls expansion and contraction in the hydraulic circuit. Is provided.
That is, the valve housing 7a of the control valve 7
Is integrally provided in the hydraulic housing 8, but the control valve 7 has an oil passage 8a communicating with the hydraulic pump 6 side provided in the hydraulic housing 8 and a lift arm cylinder 5.
The pump port 9 and the cylinder port 10 which are respectively connected to the oil passage 8b which is connected to the side, and the neutral oil return port 12 which returns the pressure oil from the pump port 9 to the oil tank 11 side and the cylinder oil return, which will be described later. Each of the ports 14 and the pilot oil return port 19 is formed. Also
15 is a spool valve, 16 is a poppet valve, 17 is an unload valve, and 18 is a check valve. Also 15a, 15
b and 15c are valve parts of the spool valve 15, 16a is a valve part of the poppet valve 16, 17a is a valve part of the unload valve 17, and 18a is a valve part of the check valve 18.

Then, in the neutral state shown in FIG. 4W, in the spool valve 15, only the first valve portion 15a is opened, and from the oil passage A for giving a back pressure to the unload valve 17 to the pilot oil return port 19. While the oil is flowing, the second and third valve parts 15b and 15c are closed,
The pressure oil from the pump port 9 is restricted from flowing into the oil passage A and the oil passage B leading to the check valve 18, so that it flows only in the oil passage C leading to the neutral oil return port 12. In this state, the unload valve 17 moves against the ammunition 17a by the pressure oil force flowing in the oil passage C, and the valve unit 1
7a is opened, whereby the pressure oil from the pump port 9 passes through the oil passage C and the neutral oil return port 12 and the oil tank 11
On the other hand, while the valve portion 16a of the poppet valve 16 is closed, the oil from the cylinder port 10 is restricted from flowing to the cylinder oil return port 14, and thus the lift arm cylinder 5 has the current length. Will be maintained in a state.

When the raising / lowering operation lever 20 is operated to the lower side, the spool valve 15 moves in the direction in which it is pulled out from the valve housing 7a (see FIG. 4X), and the poppet valve 16 also moves to the ammunition 16b. Move against. As a result, the valve portion 16a of the poppet valve is opened and the oil from the cylinder port 10 is returned to the cylinder oil return port.
As it flows to the oil tank 11 side via 14, the lift arm cylinder 5 receives the load due to the weight of the working unit 3 and shrinks, and the working unit 3 descends. At this time, the spool valve 15 is the same as in the neutral state.
Only the first valve portion 15a is open, and the pressure oil from the pump port 9 flows back to the oil tank 11 via the neutral oil return port 12.

Further, when the raising / lowering operation lever 20 is operated to the upward side, the spool valve 15 moves in the direction of being retracted into the valve housing 7a (see Y in FIG. 4).
16 does not follow the movement, and accordingly, the valve portion 16a is maintained in the neutral state and is in the closed state, while the spool valve 15 includes the first valve 15a in the closed state and the spool valve 15 in the first state. The second and third valve parts 15b and 15c are opened. Therefore, a part of the pressure oil from the pump port 9 flows to the oil passage A,
The unload valve 17 receives the urging force of the ammunition 17b and moves as close as possible to the valve portion 17a, while the remaining pressure oil flows through the third valve portion 15c in the open state to the oil passage B, and this pressure oil Due to the force, the check valve 18 moves against the ammunition 18b and the valve portion 18a is opened. As a result, the pressure oil flows toward the cylinder port 9 side and the lift arm cylinder 5
Will be extended and the working unit 3 will be raised.

Further, when the lifting operation lever 20 is operated to the upward side, in the slow rising state in which the height of the working unit 3 and the lever set position are close to each other, the rising speed of the working unit 3 is
Although it is necessary to control the speed to be slower than the normal rising speed, this is as shown in FIG. 4Z. That is, in this structure, the spool valve 15 is slightly retracted in the valve housing 7a from the neutral state. In this state, only the second valve portion 15b is opened and the remaining first and third valve portions 15a and 15c are closed. As a result, the unload valve 17 receives the pressure oil from the pump port 9 as a back pressure and closes the valve portion 17a, so that the pressure oil from the pump port 9 is locked in the control valve 7. Thus, the locking mechanism of the present invention is constituted by this.

On the other hand, in the hydraulic housing 8, the hydraulic pump 6
Side is formed with an oil passage 8a for connecting the pump port 9 of the control valve 7 and an oil passage 8b for connecting the cylinder port 10 and the lift arm cylinder 5 side. A bypass oil passage E is formed between 8a and 8b. In this bypass oil passage E, a speed adjusting spool 21 for forming a throttle valve portion 21a is screwed so as to be adjustable in and out, and a check valve 22 is further provided for preventing backflow. Then, as described above, when the pressure oil supply to the control valve 8 is locked due to the slow rising state, the pressure of the pressure oil supplied from the hydraulic pump 6 to the oil passage 8a increases, and the pressure oil is thereby increased. The oil passes through the throttle valve portion 21a while being throttled by the throttle valve portion 21a, and flows to the oil passage 8b via the check valve 22.
It is directly supplied to the lift arm cylinder 5, whereby the amount of pressure oil supplied to the lift arm cylinder 5 side is reduced and the rising speed of the working unit 3 is controlled to be decelerated. .

In the embodiment of the present invention configured as described above, the lift arm cylinder 5 causes the hydraulic oil from the hydraulic pump 6 to move when the spool valve 15 linked to the operation of the lifting operation lever 20 moves in and out of the valve housing 7a. Is supplied to extend the oil, or the oil in the cylinder flows into the oil tank 11 to be reduced, whereby the lifting and lowering control of the working unit 3 is performed. Then, during the raising control of the working unit 3,
When the lever set position of the raising / lowering operation lever 20 is close to the height of the working portion, the ascending speed is controlled to be decelerated. At this time, the pressure oil from the hydraulic pump 6 is
It is supplied to the lift arm cylinder 5 in a throttled state through a bypass oil passage E with a throttle mechanism formed in the hydraulic housing 8 without passing through the control valve 7 as in the conventional case, whereby a working unit is provided. 3 rises in the deceleration control state.

As described above, according to the present invention, the ascending speed of the working unit 3 can be decelerated and controlled to be decelerated and increased. 7 is provided on the hydraulic housing 8 side. Therefore, it is not necessary to provide the control valve 7 with a throttle mechanism for performing deceleration control, and as a result, when designing and manufacturing the control valve 7, while ensuring a state that does not affect its basic function. Further, the control valve 7 does not have to deal with troublesome and complicated measures such as providing a throttle mechanism that requires a delicate open state, and when the deceleration control state is set as described above, the control valve 7 is not operated. A lock mechanism for locking the pressure oil supply only needs to be provided, and therefore the structure is simple, and the control valve 7 can be attached regardless of the throttle amount at the time of deceleration control, which differs depending on the model, achieving the versatility. You can Since the throttle mechanism provided instead of the throttle valve is formed in the bypass oil passage E on the hydraulic housing 8 side that is not directly related to the oil passages formed in the control valve 7, the control valve 7 has a complicated valve configuration. And the control valve 7 is easily manufactured.

Moreover, in this case, since the throttle mechanism has no relation with the spool valve 15, it is possible to adjust the throttle amount independently and to assemble it, so that the occurrence of defects due to machining or assembly errors can be eliminated, and reliability can be improved. A high valve mechanism can be manufactured inexpensively and in large quantities.

Further, in this device, the opening amount of the throttle valve portion 21a can be freely adjusted by the user by adjusting the appearance of the speed adjusting spool 21. Therefore, the optimum working portion 3 of the operator can be adjusted according to the skill and working conditions of the operator. There is an advantage that the slow rising speed can be arbitrarily set.

[Advantages] In summary, since the present invention is configured as described above, a throttle mechanism required for controlling the working unit ascending / descending speed is not provided in the conventional control valve device. Instead, it is provided on the hydraulic housing side. For this reason, the control valve device does not require any troublesome and complicated measures such as providing a throttle mechanism that requires delicate opening adjustment while paying attention not to impair originally required functions.
Even if the structure is not allowed to be simple and the throttle amount is different depending on the model, the control valve device can be provided regardless of this, and the versatility can be achieved in many cases. Moreover, the throttle mechanism required for deceleration control is provided on the hydraulic housing side, which is not directly related to the control valve device, so that the adjustment of the throttle amount can be performed independently without affecting the control valve device side. As a result, the reliability of the valve control is significantly improved, and the necessary deceleration control is reliably performed.

[Brief description of drawings]

1 is a side view of an agricultural tractor, FIG. 2 is a hydraulic circuit diagram, and FIG. 3 is a hydraulic housing. FIG. 4 is a developed sectional view showing the control valve in a neutral state, a lowered state, a raised state, and a decelerated raised state. In the figure, 3 is a working part, 5 is a lift arm cylinder, 7 is a control valve, 8 is a hydraulic housing, 8a and 8b are oil passages, 9 is a pump port, 10 is a cylinder port, 21a is a throttle valve part, and E is a bypass. It is an oil passage.

Claims (1)

[Scope of utility model registration request] 1. A control valve device for controlling expansion and contraction of a hydraulic cylinder for raising and lowering a working part, a pump side oil passage for supplying pressure oil from a hydraulic pump to a pump port of the control valve device, and a cylinder of the control valve device. While integrally assembled to a hydraulic housing in which a cylinder side oil passage for supplying pressure oil from a port to the hydraulic cylinder side is formed,
The control valve device is provided with a valve locking mechanism that locks the pressure oil supply from the pump port when set in the up-down speed deceleration control state, while the hydraulic housing receives the pressure oil in the lock state and the pump side A lift control valve structure for a working unit, characterized in that a bypass oil passage with a throttle mechanism for narrowing pressure oil from the oil passage to the oil passage on the cylinder side is provided.