JPS5831484B2 - hydraulic circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic circuit equipped with a hydraulic motor that drives an inertial body.

First, the first example is a machine equipped with the above hydraulic circuit.
The hydraulic excavator shown in the figure will be described.

An upper rotating body 2 is rotatably mounted on the lower traveling body 1, and a boom 3 is supported at the front part of the upper rotating body 2 so as to be able to be raised or lowered.

An arm 4 is attached to the tip of the boom 3, and a packet 5 is attached to the tip of the arm 4 so as to be able to swing.

The upper revolving body 2 is generally equipped with a hydraulic pump 6 driven by an engine and a swing hydraulic motor 8 for turning the upper revolving body 2, and the lower traveling body 1 is equipped with a traveling hydraulic motor γ.

The boom cylinder 9 that raises and lowers the boom 3 is connected to the upper rotating structure 2.
An arm cylinder 10 for swinging the arm 4 is attached to the middle upper part of the boom 3, and a packet cylinder 11 for swinging the packet 5 is attached to the upper part of the arm 4.

Each of the hydraulic actuators described above is driven by pressure oil discharged from the hydraulic pump 6.

Normally, the driving force of the swing hydraulic motor 8 is smaller than the swing inertia, so one drive circuit always reaches the maximum pressure when starting or stopping a sudden swing.

Since this maximum pressure is maintained by a safety valve, high pressure oil is relieved and energy is lost.

On the other hand, during normal loading work, the raising operation of the boom 3 by extension of the boom cylinder 9 is combined with the turning operation of the upper revolving structure 2, and the packets containing earth and sand are moved to the unloading position of a dump truck or the like.

During this combined operation, operate the operating lever all the way (ON/OFF).
off operation).

In this case, a hydraulic circuit is used that eliminates the above-mentioned problem only when starting the swing.

Next, this hydraulic circuit will be explained with reference to FIG.

The suction side of the hydraulic pump 6 is introduced into the oil tank 12a, and the discharge side of the hydraulic pump 6 includes a directional switching valve 13b, a directional switching valve with check valve 13c, and relief valves 13a, 13.
A multiple directional switching valve 13 consisting of valves d and 13e, a brake valve 14 consisting of a counterbalance valve 14c, and relief valves 14a and 14b are installed.

The multiple directional control valve 13 is suspended from the boom cylinder 9,
The brake valve 14 is suspended from the swing hydraulic motor 8.

A return pipe of the multiple directional switching valve 13 is introduced into the oil tank 12b.

There are various means for switching the directional control valves 13b and 13c, such as manual, hydraulic pilot, pneumatic pilot, and electromagnetic means, but they are not particularly relevant and will therefore be omitted here.

If pressure oil is supplied to the head chamber of the boom cylinder 9, the boom will rise, and if pressure oil is supplied to the rod chamber, the boom will lower.
When supplied to the hydraulic motor 8, the upper revolving body rotates.

Normally, the pressure P on the head side of the boom cylinder 9 when raising the boom.

and each IJ IJ-F valve 13a. 13d, 13e, 14
a, 14)+ set pressure P13a, P13d, P13o
, P14a, and P14b have the following magnitude relationship.

P o < P 14 a= P 14 b< P 1
3 a< P 13 d = P] 36 Now, if you switch the directional control valves 13b and 13C to the right position, and simultaneously operate the elevation lever and rotation lever to raise the boom and rotate the upper rotating structure, the boom The pressures of both the cylinder 9 and the swing hydraulic motor 8 are P, which is the lower one.

(ignoring pressure loss in piping, etc.), the pressure of the swing hydraulic motor 8 does not reach the pressure of Pt+l), and there is no relief.

Even in this case, the counterbalance valve 14C is in the neutral position when stopped (swinging brake), so the relief valve 1
4a relieves.

Furthermore, if the turning angle is small during the above-mentioned combined operation, the amount of lift of the boom will be insufficient due to lack of time, and the packet may not rise to a predetermined height.

In this case, it is necessary to operate the swing lever while adjusting it appropriately (for example, operating it slowly), which significantly impairs the operability.

This invention utilizes the energy generated by relief during activation and braking of a hydraulic motor that drives an inertial body such as a revolving body in a hydraulic excavator, crane, etc., as energy that increases the amount of movement of other actuators that are operated at the same time. It is an object of the present invention to provide a hydraulic circuit that can reduce the loss of the hydraulic motor and improve the operating efficiency when the hydraulic motor and other actuators operate simultaneously.

In this invention, a second directional switching valve is interposed in the circuit connecting the hydraulic motor and the first directional switching valve, and the second directional switching valve is communicated with the rod side chamber of the single-rod cylinder. The head side chamber communicates with the actuator, and the second directional switching valve has a neutral position where the first directional switching valve communicates with the hydraulic motor and a rod side chamber of the rod cylinder with the tank, and a neutral position where the hydraulic motor communicates with the first directional switching valve. The second directional switching valve is provided with a switching position that connects a circuit connecting the second directional switching valve and a rod side chamber of the single rod cylinder, and is configured such that the second directional switching valve can be switched when the hydraulic motor and the actuator are driven. shall be.

FIG. 3 shows an embodiment of the hydraulic circuit according to the present invention,
In the figure, the same parts as in FIG. 1 are denoted by the same reference numerals.

Electromagnetic directional switching valves 15 and 16 are inserted into the hydraulic circuits 8A and 8B of the swing hydraulic motor 8, respectively, and the excitation parts of the bidirectional switching valves 15 and 16 are connected to an electric circuit equipped with a power source 23, a switch 22, and a pressure switch 21. (Represented by a broken line)
The pressure receiving portion of the pressure switch 21 is connected to a hydraulic circuit 9A connected to the head chamber of the boom cylinder 9.

The switching ports of the directional switching valves 15 and 16 are suspended in a rod chamber of a single-rod type hydraulic cylinder 17 via a shuttle valve 20, and a return oil path is introduced into an oil tank 12c.

The head chamber of the hydraulic cylinder 17 has a spring 1 that pushes the piston.
7a is housed therein, and its head chamber is connected to the head chamber of the boom cylinder 9 via a check valve 19, and is also connected to an oil tank 120 via a check valve 18.

The pressure switch 21 closes when the head side pressure of the boom cylinder 9 reaches a predetermined value.

Other details are the same as in Figure 2.

When either the switch 22 or the pressure switch 21 is open, or when both switches 22 and 21 are open, the hydraulic circuit operates in the same way as the hydraulic circuit shown in FIG. 2.

When the head side pressure of the boom cylinder 9 reaches a predetermined value and the pressure switch 21 is closed with the switch 22 closed, both the directional control valves 15 and 16 are switched to the left position.

At this time, in order to perform a combined operation of raising the boom and rotating the upper revolving structure, pressure oil is supplied to the swing hydraulic motor 8 through the directional control valve 15 or 16), and the directional control valve 13b is returned to the neutral position. When you apply the brakes to the upper rotating structure,
The counterbalance valve 14c enters the neutral state, the pressure oil discharged from the swing hydraulic motor 8 is cut off, and the pressure increases.

Pressure oil exiting the directional control valve 15 or 16 is transferred to the shuttle valve 2.
0 and flows into the rod side chamber of the hydraulic cylinder 17.

Here, the pressure reduced by an amount corresponding to the area ratio of the hydraulic cylinder and the force of the spring 17a is the boom raising pressure P.

If it is larger, the rod of the hydraulic cylinder 17 will have a spring 1
7a moves in the direction of compression, pressure oil acts on the head chamber of the boom cylinder 9 through the check valve 19, and pushes up the piston of the boom cylinder 9.

Therefore, there is no energy loss relieved from the hydraulic circuit 8A or 8B, and the amount of lift of the boom increases.

Therefore, even when the swing hydraulic motor 8 is made to make a small turn and the hydraulic cylinder 9 is operated, sufficient pressure oil can be obtained to operate the hydraulic cylinder 9 to an appropriate position.

When the compression energy of the hydraulic cylinder 17 is smaller than the swing brake energy, the hydraulic cylinder 17 becomes the most compressed state, the swing brake pressure further increases, and when it reaches the set pressure of the relief valve 14a1 or the relief valve 14b, it returns to the normal state. So there's relief there.

Once the combined operation of raising the boom and rotating the upper revolving structure is completed, other work must be done.

At this time, when the switch 22 is opened, the directional control valve 15,
16 returns to the right position in the figure, the rod side chamber of the hydraulic cylinder 17 communicates with the oil tank 12c, and the piston returns to its original position by the force of the spring 17a.

When the boom is raised to a certain height and the packet is stationary in the air (the boom cylinder 90 circuit is cut off and the pressure switch 21 is closed by the holding pressure of the boom cylinder 9), the switch 22 is accidentally closed. Even if the swing hydraulic motor 8 is operated by the swing hydraulic motor 8, pressure is only generated on the head side of the boom cylinder 9, and the boom cylinder 9
After considering the area ratio of the relief valves 13e, 13d
If the set pressure is determined in advance, the boom cylinder 9 will not operate and malfunctions can be prevented.

The pressure switch 21 is in an open state when the head chamber side of the boom cylinder 9 communicates with the oil tank 12b, such as during a combined operation of lowering the boom and rotating the upper revolving structure, so it may be accidentally Even if the switch 22 is closed, the pressure oil supplied to the swing hydraulic motor 8 will flow to the hydraulic cylinder 17 via the directional control valve 15, 16, and the driving pressure of the swing hydraulic motor 8 will drop, causing the swing hydraulic motor 8 to temporarily stop swinging. There isn't.

Fig. 4 shows that hydraulic pilot type directional control valves 151 and 16' are inserted into the hydraulic circuits 8A and 8B of the swing hydraulic motor, respectively, and the bidirectional control valves 15' and 16' and the hydraulic pilot type directional control valve 13 are connected to the boom. Another embodiment of the present invention is shown in which the pilot valve 24 is connected to the pilot valve 24.

In this figure, the same parts as in FIG. 3 are denoted by the same reference numerals.

When the boom pilot valve 24 is operated to generate pilot pressure oil, the directional switching valve 13c is switched to the right position, and the directional switching valve 15' is switched to the right position.

16' are each switched to the left position and the same operation as in the embodiment of FIG. 3 takes place.

According to the invention described above, when the hydraulic motor that drives the inertial body and another actuator are operated simultaneously,
Since the relief energy when accelerating the hydraulic motor and the relief energy when decelerating the hydraulic motor can be used as energy to drive other actuators, energy loss due to relief can be reduced and, for example, when the hydraulic motor is made to make a small turn. At times, other actuators can be sufficiently operated to appropriate positions, and simultaneous operations can be performed smoothly.

This means that when the hydraulic excavator raises the boom and makes a small turn of the upper rotating structure, the energy that is being relieved in the hydraulic circuit of the swing hydraulic motor is used to raise the boom, increasing the amount of lift of the boom. Therefore, it is possible to sufficiently match the operations of turning and raising the boom without having to adjust the turning lever appropriately to match the turning and boom raising as in the conventional case.

In addition, as an embodiment of this invention, a hydraulic motor that drives the upper revolving structure and other actuators are used as cylinders of the boom, but other actuators are used as motors that receive a relatively constant load (for example, when the crane is elevated/elevated). A similar effect can be obtained even if the winding motor is used as a winding motor.

[Brief explanation of drawings]

Fig. 1 is a side view showing a hydraulic excavator, Fig. 2 is a system diagram showing a hydraulic circuit of a conventional swing hydraulic motor and boom cylinder in a hydraulic excavator, and Figs. 3 and 4 are different implementations of the hydraulic circuit according to the present invention. It is a system diagram showing an aspect. 8...Swivel hydraulic motor, 9...Boom cylinder, 13...Multiple directional valve, 13a.
...IJ Leaf valve, 13b... Directional switching valve, 13c... Directional switching valve with check valve, 13d
, 13e...IJ IJ-fu valve, 14...
...Brake valve, 14a, 14b...Relief valve, 14c...Counter balance valve, 15.
...Solenoid directional valve, 15'...Hydraulic pilot type directional valve, 16...Solenoid directional valve, 16'...Hydraulic pilot type directional control valve valve,
17...Hydraulic cylinder, 18°19...
・Check valve, 20...Shuttle valve, 21...
...Pressure switch, 22...Switch, 23.
...Power supply, 24...Pilot valve for boom.

Claims (1)

[Claims] 1 In a hydraulic circuit equipped with a hydraulic motor that drives an inertial body, an actuator that is driven simultaneously or independently with the hydraulic motor, and a first directional valve provided in a circuit that connects the hydraulic motor and actuator with a hydraulic source and a tank, respectively. , a second directional switching valve is interposed in a circuit connecting the hydraulic motor and the first directional switching valve, the rod side chamber of the single rod cylinder is communicated with the second directional switching valve, and the head side chamber of the single rod cylinder is connected to the second directional switching valve. The second directional switching valve communicates with the actuator, and has a neutral position where the first directional switching valve communicates with the hydraulic motor and a rod side chamber of the single rod cylinder with the tank, and a neutral position where the hydraulic motor and the first directional switching valve communicate with each other. The second directional switching valve is characterized by comprising a circuit connecting the valve and a switching position for communicating between the rod side chamber of the single-rod cylinder and the single-rod cylinder, so that the second directional switching valve can be switched when the hydraulic motor and the actuator are driven. Hydraulic circuit.