JPS6037401A - Hydraulic circuit for inertia load - Google Patents

Abstract

PURPOSE:To prevent rapid increase in a hydraulic pressure on an inertia load drive side, by providing a remote control valve generating an adjustable pilot pressure, and supplying the pilot pressure to a pilot line of a selector valve and a set pressure adjusting mechanism of a relief valve. CONSTITUTION:A remote control valve generating an adjustable pilot pressure is connected to a pilot line and a set pressure adjusting mechanism 4 of a selector valve 2 and a relief valve 3, respectively, which are provided in a discharge line of a pump 1. With this arrangement, a set pressure of the relief valve 3 defining an upper limit of a hydraulic pressure on an inertial load drive side may be modified and adjusted according to a quantity of operation by an operator, thereby preventing rapid increase in the hydraulic pressure on the inertia load drive side.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic circuit for driving and controlling a rotating body having inertia in a power shovel, a hydraulic crane, etc., that is, an inertial load.

For example, a conventional hydraulic circuit that drives and controls the upper revolving body (inertial load) of a power excavator has a main pump that is the hydraulic pressure source for drive control, and is installed between the main pump's discharge pipe and return pipe. The IJ IJ- consists of a valve, a switching valve, a hydraulic motor connected to both of the pipes and directly controlling the upper rotating body, and the operating pressure oil discharged from the main pump is switched to the hydraulic motor by the switching valve. The structure is such that the inertial load is driven and controlled by supplying the inertial load and rotating the hydraulic motor in the forward and reverse directions.

However, in the conventional inertial load hydraulic circuit f, when the inertial load, for example 6 workpieces, is operated to open the switching valve to slightly start the upper revolving structure, the upper revolving structure is directly driven. An abnormally high pressure builds up on the inlet side of the hydraulic motor to be controlled until the steady drive state is reached due to the influence of the inertia of the upper rotating body, and as a result, the upper rotating body (inertia load) is much higher than the operator intended. It has the disadvantage of rapid acceleration, which can lead to erroneous operation. This phenomenon becomes particularly noticeable when a closed center type pulp that does not have a neutral 19427 function is used for the switching valve.

The present invention was developed to eliminate the above-mentioned drawbacks in conventional hydraulic circuits for inertial loads. A relief valve and a switching valve are provided between the pipe line and a remote control valve that outputs an adjustable pilot pressure, and the pilot pressure is connected to the switching valve and the IJ I.
It is characterized in that it is used as the control pressure of the set pressure adjustment mechanism provided on the J-F valve, and its purpose is to determine the upper limit of the working oil pressure on the inertial load drive side. By controlling the switching of the switching valve corresponding to the operating amount of the onitor and making it possible to change and adjust it in connection with the same control, a sudden increase in the hydraulic pressure on the inertial load drive side can be prevented and the above-mentioned drawbacks can be avoided. The point is that it provides a hydraulic circuit with no inertial load.

The present invention has the above-mentioned configuration, and a relief valve and a switching valve are provided between the discharge pipe and the return pipe of the main pump, which are the drive control hydraulic power source for the inertial load, and the pilot pressure can be adjusted. Since the pilot pressure is used as the control pressure of the set pressure adjustment mechanism provided in the switching valve and the IJ-F valve, when starting the inertial load at a slow speed, the remote control valve outputs When the operating valve is operated by a small amount to output a low pilot pressure, the opening degree of the switching valve is reduced according to the pilot pressure a, and the amount of operating pressure oil supplied to the inertial load drive side is reduced. By the set pressure adjustment mechanism operated by pilot pressure, IJ
The set pressure of the IJ-F valve is lowered in synchronization with the switching operation of the switching valve in accordance with the pilot pressure, and the hydraulic pressure of the hydraulic oil at the time of startup becomes appropriate, thereby preventing sudden acceleration of the inertial load, that is, runaway. , the drive control performance of inertial loads is significantly improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

An embodiment of the present invention is shown in the attached diagram, in which (1) is the main pump which is the hydraulic pressure source for drive control of the inertial load (α), and (11) is the discharge side of the main pump (1). (12) is a return pipe connected to the tank; (3) is a return pipe connected to the tank;
) is the IJ IJ-7 valve provided between the discharge pipe (11) and the return pipe (12), and (2) is the switching valve provided between the discharge pipe (Ah) and the return pipe (12). , (5) are connected to the discharge pipe (11) and the return pipe (12) to carry the inertial load (α
) is a hydraulic motor capable of forward and reverse rotation that directly drives and controls the hydraulic motor (5). The hydraulic motor (5) is driven in the forward and reverse directions by being supplied to the side and drained from the return pipe (e2).

Furthermore, in this embodiment, a remote control valve (8) that receives supply pressure from the sword and outputs a pilot pressure (secondary pressure) that can be adjusted according to the operation amount is provided. The relief valve (3) is provided with a set pressure adjustment mechanism (4), and the relief valve (3) is provided with a set pressure adjustment mechanism (4), so that the control pressure can be supplied as a reciprocating control pressure of the switching valve (2) through the dotted line. Pressure adjustment mechanism (4)
The pilot pressure is supplied as a control pressure through a shuttle valve (9).

Further, the set pressure m14 node mechanism (4) has a cylinder into which the nozzle pressure flows as shown in the figure, and the nozzle pressure operates a piston to adjust the nozzle pressure. The spring pressure, that is, the set pressure of the relief valve (3) is increased or decreased in proportion to the pilot pressure.

The illustrated embodiment of the present invention has the above-described configuration, so that when the remote control valve (8) is moved by a desired amount to the right or left in the drawing, the valve ξ corresponding to the amount of movement is moved.
The pilot pressure is outputted, and the pilot pressure passes through the dotted line and is applied as a control pressure to the right side or left side of the switching valve (2) in the figure, and the switching valve (2) is controlled to switch. In synchronization with the switching control, the pilot pressure is supplied as a control pressure to the set pressure regulator (4) via the shuttle valve (9), and the IJ-IJ-f valve (3
) is changed and adjusted.

Therefore, when the inertial load (α) is slightly activated, the remote control valve (8) is slightly operated, and a low pilot pressure is output. Therefore, when the aforementioned low pilot pressure is added to the switching valve (2) as a control pressure, the switching valve (2)
is switched and the opening degree corresponds to the pilot pressure, so that the inertial load (α) side, that is, the hydraulic motor (5)
At the same time, the set pressure of the set pressure adjustment mechanism (4) changes in synchronization with the switching valve (2), and the set pressure, that is, the set pressure of the relief valve (3), changes. Since the set pressure is low corresponding to the low pilot pressure, the hydraulic pressure of the hydraulic oil on the inlet side of the hydraulic motor (5) is prevented from rising excessively and reaches the desired upper limit hydraulic pressure, which reduces sudden acceleration of the hydraulic motor, that is, inertial load. The inertial load can be started easily and smoothly by adjusting the remote control operation of the starter, and the drive control performance of the inertial load can be significantly improved.

Although the above embodiment has been described using a hydraulic motor, similar effects can be obtained when an actuator is used.

Although the present invention has been described above with reference to embodiments, it goes without saying that the present invention is not limited to such embodiments, and that various design modifications can be made without departing from the spirit of the present invention. .

[Brief explanation of the drawing]

The attached figure is a hydraulic circuit diagram of an inertial load showing one embodiment of the present invention. 1: Main pump 2: Switching valve 6: Relief valve 4: Set pressure adjustment mechanism 5: Hydraulic motor 7: Pilot pump 8: Remote control valve 9: Shuttle valve α: Inertial load ll: Discharge pipe line 12: Return pipe line return Agent: Patent attorney: 6 people who are not members of Kaihon Important Cultural Properties

Claims (1)

[Claims] A relief valve and a switching valve are installed between the discharge pipe and return pipe of the main pump, which is the hydraulic power source for drive control of the inertial load.
A remote control valve that outputs an adjustable pilot pressure is provided, and the pilot pressure is connected to the switching valve and the IJ.
An inertial load hydraulic circuit characterized by a configuration in which the set pressure adjustment mechanism provided in the IJ valve is used as a control pressure.