JPS59118930A - Operational speed controller for double-acting working part - Google Patents

Abstract

PURPOSE:To raise the fine operability of a double-acting working part by enabling it to be set to optimal working speed according to the operations of an oil- pressure cylinder by a method in which a flow rate control valve is provided to an oil path between an oil-pressure cylinder and its control valve, and an escape oil path is provided to the flow rate control valve. CONSTITUTION:A flow rate control valve 8 is provided between an oil-pressure cylinder and its switch valve 5. In the flow rate control valve 8, a spool 17 is movably supported by springs 9 and 12 in the body 14, oil chambers are provided in the spool 17 and also before and behind of the spool 17, and oil paths 6 and 7 and an escape oil path 11 are led to each oil chamber. When pressure oil of more than a fixed pressure flows into the flow rate control valve 8 through pipelines 6 and 7, the escape pipeline 11 is opened to allow the pressure oil to discharge, and thereby optimal operation speed can be obtained for the oil- pressure cylinder 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an operating speed control device for a double-acting operating part such as an operating cylinder installed in a working machine such as a front loader or rotary mounted on a tractor.

Recently, it has become increasingly common for these working machines attached to tractors to be driven by the tractor's hydraulic system, but since this hydraulic system was originally used to operate the working machine lifting mechanism, The oil pressure and flow rate are sufficiently large. Therefore, when the operating section of the work machine has a small capacity, the flow rate of the hydraulic system is too large, and as a result, the operating speed of the operating section is too fast, making it impossible to perform fine movement operations, making the operation difficult. As a countermeasure to this problem, it is possible to install a flow rate adjustment device in the tractor's hydraulic system to adjust the flow rate and then supply it to each operating part, but since there are many different hydraulic supply systems, Performing suitable flow rate adjustment at one location requires an extremely complicated structure and is difficult to implement.

There is also a method of forcibly restricting the flow rate using a simple orifice or the like, but this creates problems such as overloading the hydraulic pump because high resistance acts on the discharge side of the hydraulic pump.

Therefore, in this invention, a flow control valve is provided between a double-acting operating section of a working machine mounted on a tractor and a switching valve that controls the supply and discharge of pressure oil to this operating section. The relief part is opened by the pressure oil flowing in while maintaining a constant pressure, and the hydraulic pressure of this pressure oil is lowered. The system is designed to supply the most suitable flow rate to each area using a flow control valve with a simple structure.

To explain the specific structure based on an illustrated embodiment, the hydraulic circuit illustrated in FIG. The piston (1a) is a double-acting operating part (2), and the pressure oil of the hydraulic pump (3) installed on the tractor is supplied to the relief valve (4).
) and is connected so that it can be supplied to or discharged from the oil passage (6) or oil passage (7) before and after the lift piston (1a) via the double-acting switching valve (5). . A flow control valve (8) is connected between the double-acting actuator (2) and the switching valve (5), and the flow control valve (8)
The pressure in the oil line (6) connected to the pump (3) is caused by the spring (
When the force exceeds the force 9), the valve O1 moves and a part of the pressure oil that should flow into one oil chamber (2a) K of the double-acting actuating part (2) is transferred from the oil passage (6) to the relief part 01. ) to the oil passage (7), and when the oil passage (7) is connected to the oilfield pump (3), the pressure in this oil passage (7) can control the force of the spring 021. Since the valve (1) moves to open the passage from the oil passage (7) to the oil passage (6), a portion of the pressure oil that should flow into the other oil chamber ('2b) flows into the oil passage (6).
).

An example of the commercialized flow control valve (8) is shown in Fig. 2, where the poppet On (1st south corresponds to the valve (11, 031) with a throttle OQ in the hole 09 of the valve body 04) ) is inserted, but when the hydraulic pump (3) is connected to the oil passage (6) and pressure oil flows from this oil passage ``6'' into the hole (19), it flows against the spring (9). The poppet [η moves to the left and the relief hole O1O is connected to the boat (IIK, so a part of the pressure oil in the oil passage (6) escapes through the relief part fl + 3K through the valve stop, bow) Ql. Also, when the oil passage (7) is connected to the hydraulic pump (3) and pressure oil flows in from the oil passage (7), the poppet aη moves to the right against the spring UK and closes the relief hole. 0 & will be in communication with the boat (A), and a part of the pressure oil in the oil passage (7) will escape to the relief part 0υ via the relief hole 081° boat ■.

Then, as shown in the figure, a part of the pressure oil in the busy oil passage (6) or (7) is transferred to a switching valve ('271.
The structure is such that it returns to the tank via the control valve r21J of the work equipment elevator #IQ, 1, etc., or directly to the tank (C)K (although not shown), so that the lift piston of the lift cylinder (1) The hydraulic pressure of the pressure oil supplied to the lift piston (1a) decreases, and the lift piston (1a)
) will be slowed down.

Nao, N! In addition to the illustrated example, control valves (8) having other structures having the same functions as those described above may be used.

The operating speed control device for a double-acting operating section according to the present invention is constructed as described above, and is caused by pressure oil flowing in exceeding a preset pressure. Since the hydraulic pressure of the pressure oil is lowered and the inflow direction of this pressure oil is configured to be reversible, the double-acting operating part can be operated at a suitable operating speed that suits its properties. Therefore, it is possible to always maintain a suitable operating speed regardless of the type of tractor or the capacity of the hydraulic stomach. In addition, since it is attached to a busy operating part, the structure is simple, and since it is a reversible type, only one flow control valve is required, making it possible to put it into practical use at low cost. be.

[Brief explanation of drawings]

The figures show one embodiment of the present invention, FIG. 1 is a hydraulic circuit diagram, and FIG. 2 is a sectional view of a flow control valve used in the same circuit. Description of symbols (1)...Lift cylinder (2)...Double acting actuating part (3))...Hydraulic pump (4)...Relief valve (fi)...Switching valve (6)・
・Oil passage (8)...Flow rate control valve (10...Relief part Patent applicant Iseki Agricultural Machinery Co., Ltd.

Claims (1)

[Claims] A flow control valve is provided between a double-acting operating section of a working machine mounted on a tractor and a switching valve that controls the supply and discharge of pressure oil to this operating section, and this flow control valve is set to -U. The double-acting type actuator is characterized in that the inflow direction of the pressure oil is configured to be reversible so that the pressure oil flowing in exceeding the pressure opens the relief part and lowers the oil pressure of the pressure oil. section operating speed control device.