JPS5841127A - Hydraulic close circuit for driving revolving body - Google Patents

Abstract

PURPOSE:To enable to perform an idling opertion at a neutral time, by a method whereing lines, connecting a variable capacity hydraulic pump and a revolving hydraulic motor, are connected with a line provided with a switch valve connecting only at a neutral position time, and the lines are connected only at a neutral position time of a revolving lever. CONSTITUTION:A hydraulic circuit is constituted such that a variable capacity type hydraulic pump 2, driven by a prime mover 1, and a revolving hydraulic motor 3 for revolving body 4 are connected together with lines 6 and 7. In the hydraulic circuit, a line 22, provided with a swithch valve 25 which can be connected only at a neutral position, connects the lines 6 and 7, and through control of a hydraulic or mechanical revolving lever 5 which controls switching of the variable capacity type hydraulic pump 2, a revolving lever 5 switches the switch valve 25 so that the lines 6 and 7 in the hydraulic circuit are connected together only at a neutral position time. Thus, even if the revolving lever 5 is suddenly switched to a neutral position, a smooth idling operation can be performed, and the revolving body 4 can be held in an inactive state at a revolving drive time.

Description

Detailed Description of the Invention: The upper part of the present invention is rotatably installed on a base such as a running body, and is used as a hydraulic pump driven by a variable speed prime mover. The present invention relates to a hydraulic pump control type hydraulic closed circuit configured by connecting a bidirectional hydraulic motor for driving a revolving structure through two pipes.

First, a hydraulic closed circuit of a general hydraulic pump control system used in mobile cranes will be explained. A variable speed prime mover that can freely change the rotation speed like the lFi engine, both butcher hydraulic pumps driven by the 'aFi prime mover IK, a 3-wire hydraulic pump 2 and two oil supply and drainage pipes6. 7) is connected to a bidirectional hydraulic motor to form a hydraulic closed circuit; 4 is a revolving body which is driven to rotate by the hydraulic motor; Ru. 9 is a servo piston that operates the swash plate of the hydraulic pump 20; 8 is a switching valve that operates the servo piston; these constitute a hydraulic pump control device. The left and right operation chambers of the switching valve 8 are pilot pipes 11.1! Rotate through / (-5K
When the swing lever 5 is operated, the switching valve 8 is switched depending on the operating direction, and the hydraulic pump 1 is connected to the pipe 6.7 via the pilot pipe 13.14.
The supply direction from 5 to the servo piston 9 is switched and the hydraulic pump! ! The inclination direction of the O swash plate is changed, whereby the hydraulic pump 2 is configured to be able to discharge pressure oil in the forward and reverse directions, and the position of the servo piston 9, that is, the fR inclination angle of the swash plate is controlled by feedback pressure. This is done so that the discharge amount can be controlled. In addition,
16 is a high pressure relief valve that regulates the maximum pressure in the circuit;
7 is a hydraulic pump that replenishes pressure oil into the circuit, and the discharge side is a check valve 18. connected to γ to the conduit via XI;
And to the oil tank 21 via the low pressure relief valve 2o that sets the circuit 0 minimum pressure! It is connected.

In this hydraulic closed circuit, the swing lever S is at the neutral position Kl.
Then, the switching valve 84 is in the neutral position KTo), and therefore the servo piston S is also in the intermediate position, and the hydraulic pump 20 swash plate #1 is in the neutral position.
It is not tilted and discharges 13 hydraulic pumps t%/
Therefore, the revolving structure 4 driven by the hydraulic motor 3 is stationary. %/%), the servo piston 9 is moved by the oil discharged from the hydraulic pump 15, so the diagonal 4N of the hydraulic pump 2 is tilted.
Since the hydraulic pump 2 discharges oil and the hydraulic motor 3 is rotated, the rotating body 4 also rotates. When the swing lever 5 is then returned to the neutral position, the swash plate of the hydraulic pump 2 is held at a position where the pressures in the pipes 6 and 7 are equalized, and the swing body 4 continues to swing (due to inertia). This turning state due to inertia is the drifting operation necessary to prevent the suspended load from swinging out to zero.

In this device, b.
After turning the body 4, return the turning lever 5 to the neutral position to perform flow operation, and when the rotational speed of the prime mover 1 is suddenly lowered, the rotational speed of the prime mover 1 is suddenly reduced, and when the pump swash plate inclination angle is near the maximum, the pump Since the decrease in the discharge amount O due to the decrease in rotational speed cannot be compensated for by increasing the swash plate inclination angle, the discharge amount decreases rapidly and the rotational speed of the rotating body 40 decreases rapidly), - causing load swing. This invention has the drawback that the above-mentioned 9 hydraulic closed circuit KThvh rapidly reduces the rotational speed of the prime mover when the swing lever is trapped from the swing body drive position to the neutral position. It is an object of the present invention to provide a hydraulic closed circuit for driving a revolving superstructure that does not cause load swing even when the vehicle is in use.

The present invention provides a mechanically operated switching valve and a hydraulically operated switching valve between two oil supply and discharge pipes connecting a hydraulic pump and a hydraulic motor for driving a rotating body driven by its discharged oil. The switching valve is connected to a conduit having a swivel lever, and is configured so that the switching valve is in a communicating state at a neutral position and in a swiveling state at a rotating body driving position. In FIG. 2, in which the present invention (Embodiment 0) is explained below with reference to FIG. 2, the same reference numerals as in FIG. 1 indicate the same components.
2 is a pipe line 6 connecting the hydraulic pump 2 and the hydraulic motor 3;
If the switching valve in this case is in the neutral position, the pipe @g is inserted into the pipe connecting between 7 and 23.
The red 231 is a 2-point 3-position switching valve that communicates with the snow and has two positions on both sides.
When the swing lever 5 is in the neutral position, the switching valve is also in the neutral position, and the swing lever 5 is in the drive position of the swing body 4, that is, in the diagonal position of the hydraulic pump 2. When the plate operating switching valve 8 is operated to the left or right position, it is configured to switch to both sides.

In this configuration, when the swing lever 5 is switched to the swing body 40 drive position, the switching valve 8 is switched and oil is discharged from the hydraulic pump 2, but at the same time, the movement of the swing lever SO is transferred to the switching valve via the link mechanism 24. Since the operation red 13aK is transmitted and switched from the neutral position (communicating state) to the push position, the pressure oil discharged from the hydraulic pump to the pipe 6 and 7 is supplied to the hydraulic motor 3, and the hydraulic motor is rotated, and the rotating body 4 turns. Here, when the swing lever 5 is returned to the neutral position fK, the switching valve 23 is also returned to the neutral position via the link mechanism 24, and between the pipes 6 and 7, the pipe 2 and the switching valve 2
3. Nineteenth, even if the rotational speed of the prime mover 101f is suddenly reduced, the oil discharged from the hydraulic cage 3 rotated by the inertia of the rotating body 4 flows through the pipe 22 and the switching valve 23, Hydraulic motor 3Hiro rotating body O Rotates by inertia force and enables smooth running operation O Figure 3 As a switching valve installed in the pipe line 22, the above-mentioned mechanically operated switching valve 0) K, hydraulically operated type A 3-position switching valve 25 is provided, and the operation chambers on both sides of the switching valve 25 are connected to the pivot lever 50 pipes 11 and 12 through pilot pipes 26 and 27, respectively. be. Similarly to the switching valve 23, the cough switching valve 2s also communicates with the pipe line 28 at the neutral position and blocks the pipe line 28 at both sides. When operated, the pilot pressure is applied to the switching valve 8 through the pipes 26 and 27, and at the same time the pilot pressure is applied to the switching valve zsK (rounding and scissor switching valves are also switched), and the pipe type 3 is switched to the blocked state and 1 If you move the swing lever 5 to the neutral position KN, it becomes a switching valve! ! S also returns to the neutral position and is rounded to bring the pipe line 22 into a communicating state, producing the same effect as described above.

Note that when implementing the present invention, it is also possible to use a two-position switching valve as the switching valve provided in the conduit 22. However, the structure of the operating means tends to be more complicated than in each of the above embodiments. (9) In an actual hydraulic closed circuit, for example, a shuttle valve is provided between pipes 6 and 7, and a low pressure relief valve (the low pressure relief valve 20 or a separate relief valve) is provided on the outlet side of the shuttle valve; A brushing system including an oil cleaning device is provided between the low pressure relief valve and the oil tank 21, but the present invention o:g! As stated above, according to the present invention, even if the prime mover rotational speed suddenly drops when the swing lever is returned to the neutral position, Since smooth flow operation is possible, load swing can be prevented, heat can be avoided, and inching performance can be improved. In addition, when the swing lever is in the neutral position KTo, the two O oil supply and drainage pipes that connect the hydraulic pump and the hydraulic motor are short-circuited, so the hydraulic pump control μm control device O neutral is disturbed for some reason. Even if oil is discharged from the hydraulic pump, the discharged oil flows R through the switching valve and the pipeline that short-circuits the two pipelines, and the rotating body remains stationary without rotating, thereby preventing the load swinging. The present invention has the advantage that it can be installed relatively easily and inexpensively without changing the basic configuration of an existing hydraulic closed circuit.

[Brief explanation of the drawing]

Figure 1 is a hydraulic circuit diagram of a mobile crane that applies a general hydraulic closed circuit.
Hydraulic circuit diagrams each showing an example. , 8・◆
Switching valve, 9-・Servo piston, 11.1 & 26, 27
・・By-pass pipeline, 23.25・・Switching valve patent applicant Hitachi Reef Machine Co., Ltd. Agent Patent attorney Hikiyoshi Akimoto Agent Patent attorney Waka 1) Masaru - Figure 3

Claims (1)

[Scope of Claims] 1. A rotating body in which both sarcoma hydraulic pumps driven by a variable speed prime mover and both inner lid hydraulic motors for driving the rotating body are connected by two oil supply and drainage pipes. In the driving/driving hydraulic closed circuit, the two O oil supply/drainage pipes are connected by a pipe having a mechanically operated switching valve and a hydraulically operated switching valve. Hydraulic closed circuit for driving a rotating body O1, characterized in that the hydraulic closed circuit for driving a rotating body is configured such that it is in an appropriate state when the turning lever that operates the control device is in a neutral position and is in a four-wheeled state when it is in a rotating body driving position. A hydraulic closed circuit for driving a rotating body according to claim 1, wherein the switching valve is a two-bottom, three-position switching valve.