JPS62160323A - Free-slewing system of oil-pressure shovel - Google Patents

Abstract

PURPOSE:To permit functions matching various kinds of operations to be selected by the same machine by providing an oil path having paired working oil paths connected by a shuttle valve, etc., and a switch valve for the pressure oil-flowing-in and out port of an oil-pressure motor. CONSTITUTION:When the spool of an electromagnetic switch valve 15 is D under a condition that a switch 22 is opened, oil paths 30 and 31 are interrupted and oil paths 6 and 7 form an independent circuit. A slewing operation lever 25 is operated, an oil-pressure motor 5 is normally or reversely turned, and an upper slewing body is stopped by a great deceleration force. When the switch 22 is closed, the valve 15 is switched to E, a slewing free valve 14 is opened, and oil pressure in the oil paths 6 and 7 freely flows into other oil paths through each shuttle valve 13. When the lever 25 is restored to neutral, the motor 5 turns freely by the inertia of the upper slewing body without breaking torque. The efficiency of operations can thus be enhanced according to various conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a hydraulic system that can selectively freely rotate a hydraulically driven rotary body having a large inertial force.

Conventional technology By replacing the front acnotchment of the hydraulic Noyohell, it can be used not only as an earth-moving machine such as a backhoe or a loading shovel, which is its original purpose, but also as a cargo-handling machine with the characteristics of a mobile crane. Although it is often used, the functionality of the swing drive system of the superstructure has given it performance suitable for most commonly used earthmoving machines. In other words, when the swing operation lever is returned from the swing position to the neutral position, the inertia of the swing body is automatically absorbed by the hydraulic brake of the hydraulic motor, and the hydraulic brake is forcibly stopped and held. The circuit system is used to improve the safety and cycle time of earthwork work. An embodiment of this type of hydraulic circuit is as shown in FIG. 5 rotates in the forward or reverse direction, and rotates the upper revolving body using a revolving pinion, gears, etc. When the hydraulic switching valve 4 is set to the neutral position, that is, the C position during the swing I1 movement, the pressure oil supply from the main pump 2 is cut off, and the oil passages 6.7 leading to the oil inflow and outflow ports of the swing motor 5 are closed. Both are closed by the spool of the hydraulic switching valve 4, but the rotating motor 5 is forced to rotate due to the rotational inertia of the upper rotating body, so oil is sucked in from one port, becomes high pressure, and is released from the other port. It is discharged. This discharged high pressure oil passes through the relief valve 8' or 8 and the oil passage 6 on the low pressure side.
or 7, and is sucked in again from the port on the opposite side of the hydraulic motor 5. This operation is repeated, and while the pressure oil passes through the relief valve 8.8' and becomes low pressure, the rotational inertia energy of the upper rotating body is consumed and the speed gradually decreases, until it finally stops and maintains its position. become. That is, when the hydraulic switching valve 4 is switched to the C position from the state in which the upper rotating body of the hydraulic excavator is turned, hydraulic braking torque is automatically generated in the hydraulic motor 5 to reduce the turning speed of the upper rotating body.
This gives you the ability to stop it in a short amount of time. Note that in order for the hydraulic motor 5 to generate braking torque, the hydraulic motor 5 must
The oil chamber of the operating part must be filled with oil, and if it leaks from the oil-sealed part during braking and there is insufficient oil during rotation, it will not be possible to exert braking torque.To prevent this, the oil passage 6
and 7 are constantly supplied with oil from the main return circuit 10 from the swing motor and other actuators via the oil line 11 via check valves 9 and 9. On the other hand, the hydraulic switching valve 4 is in the neutral position C. A relief valve 12.12' is provided to prevent abnormally high pressure from being trapped in the oil passage 6.7 for some reason.

The above-mentioned upper revolving body drive system with a hydraulic circuit configuration has advantages when used as an earth-moving machine or some load-throwing machines, but on the other hand, when changing the front attachment and using it for other purposes, it is difficult to operate the upper structure. There are often pros and cons. For example, in a general hydraulic backhoe equipped with a poom 34, an arm 35, and a backhoe packet 36 as shown in FIG. When moving the vehicle or to a predetermined position, the swing brake is automatically applied by simply setting the swing control lever to neutral, making it easy to stop the vehicle at a predetermined position. Even if there are
This is effective because it allows you to maintain a fixed position for a short period of time without performing any operations. On the other hand, as shown in FIG. 3, when a winch box 37 is attached to the tip of an arm 35, a hook block 38 is suspended by a wire rope 40, and a load 39 is handled, the load 39 is lifted and the upper part is rotated. When the body is turned and moved to a predetermined position and the swing operation lever is returned to neutral, the winch box 37 that moves together with the upper swing structure attempts to stop with a large deceleration due to the swing brake force, and the suspended load 39 This results in pendulum movement due to inertial force, making it extremely difficult to determine a predetermined position. Conventionally, a machine equipped with such an actuation mechanism has been operated by a skilled operator who carefully and slowly accelerates and decelerates the swing to prevent pendulum movement from occurring in the suspended load 39. In addition, a high degree of skill is required to follow the swinging motion of the suspended load 39 in accordance with the pendulum motion to stop the swinging, otherwise the cycle time would be reduced.

Also, in cargo handling work, as shown in Fig. 4, the arm 4
In a load dumping machine in which a gripping tool 42 of wood or other material is directly attached to the tip of the machine, pendulum movement is difficult to occur even when a swing brake force is applied, and it is better to forcibly stop the swing to improve cycle time. This makes positioning of luggage easier.

Problems to be Solved by the Invention As mentioned above, when the front attachment of a hydraulic excavator is reequipped and used for various purposes, a swing brake force is applied when the swing operation lever is set to neutral depending on the type of work. This can be an advantage or a disadvantage, so in a single hydraulic excavator, automatic braking performance and free turning performance when the swing operation lever is in the neutral position can be freely selected with just N operations. The aim is to realize a hydraulic circuit system that can do this.

In order to have a function that is more than just a means to solve the problem, this invention has the following hydraulic/electrical circuit configuration.

That is, a shuttle valve is connected between a pair of hydraulic oil passages connected to a pressure oil flow/outflow port of the hydraulic motor, and an oil replenishment circuit from the outlet port of the shuttle valve to the hydraulic oil passage of the hydraulic motor. Configures the oil passage. Then, in the middle of the cedar oil path, there is a pilot switching valve (hereinafter referred to as a swing free valve) whose internal oil path is normally open but is closed when the pilot is positive, and an electric signal, hydraulic pressure signal, or A switching valve is provided to manually open and close the internal oil passage. In addition, the pilot oil chamber of the pilot switching valve is provided with a limit switch that is linked to the operating lever of the manually operated lever-type hydraulic switching valve for operating the hydraulic motor and that opens an electric circuit only when the operating lever is in the neutral position. The pressure oil discharged from the pilot pump is guided through an electromagnetic switching valve that opens and closes the internal oil passage in response to an electric signal.

Operation: Switch the switching valve in the middle of the communication oil path between the outlet port of the shuttle valve provided between a pair of hydraulic motor operating oil paths and the oil replenishment circuit to an open state by an electric signal, hydraulic signal, or manually. .

In this state, when the swing operation lever is in the neutral position and the electric circuit of the limit switch is open, that is, when no swing operation is being performed, the solenoid switching valve is not energized and the internal oil passage is connected to the pyro pump. Since no pressure oil is supplied to the pilot oil chamber of the swing free valve, the circuit remains open, and one oil path of the hydraulic motor operating oil path is connected to the shuttle valve, swing free valve, and switching valve. It also communicates with the other hydraulic motor hydraulic oil passage through a check valve for the replenishment circuit. As a result, the pair of hydraulic oil passages that supply pressure oil to the hydraulic motor communicate with each other, and the hydraulic motor can be easily rotated by external force.

Next, when the electric circuit of the mint switch is closed in conjunction with the swing operation lever, that is, when the swing operation is started, the solenoid switching valve is energized, and the pressure oil from the pilot pump flows through the internal oil path of the solenoid valve. The oil flows into the pilot oil chamber of the swing free valve and closes the swing free valve, and the pair of hydraulic motor operating circuits are mutually cut off by the shuttle valve and become independent circuits. The turning acceleration is made. After turning is started, when the operating lever is returned to neutral, the free turning valve opens again and the circuit returns to the free turning state.

In addition, when the switching valve located in the middle of the communication oil passage is set to the closed position by an electric signal, a hydraulic signal, or manually, the pair of hydraulic morph hydraulic oil passages become independent regardless of the position of the operating lever for operating the hydraulic motor. This results in a circuit state similar to that of a normal hydraulic excavator swing system shown in FIG.

Embodiment An embodiment of the present invention will be explained with reference to the drawings. FIG. 1 is a hydraulic/electrical circuit diagram showing an embodiment of the present invention, l is an engine that drives a main pump 2 and a pilot pump 3; Oil is sucked in from 21 through a suction strainer 19, and the discharged oil is pressure regulated by a relief valve 17 and communicates with a manually operated lever-type hydraulic switching valve 4 for operating the swing motor 5, and the operating lever 25 of the switching valve 4 is in the neutral position. That is, in the C position, the pressure oil passes through the C position open oil passage and the oil passage 24, reaches another hydraulic switching valve (not shown), and then merges with the return oil passage of the other hydraulic switching valve group to enter the main It becomes the return circuit 10 and flows into the tank 21. When the operating lever 25 of the hydraulic switching valve 4 is pushed or pulled, the spool of the hydraulic switching valve 4 moves and switches to the A or B position, and the pressure oil discharged from the main pump 2 is transferred to the oil path 6, the hydraulic motor 5, and the oil path. 7. It flows to the tank 21 through the A position passage of the hydraulic switching valve 4, or to the tank 21 through the oil passage 7, the hydraulic morph 5, the oil passage 6, and the B position passage of the hydraulic switching valve 4, and the hydraulic motor 5 is It functions to rotate or reverse. Reference numeral 8.8 is a relief valve which is opened from oil passages 6 to 7 and from oil passages 7 to 6, respectively, and allows the hydraulic excavator's upper rotating structure, which has a large inertia, to be rotated by the hydraulic motor 5. This is to prevent the oil passages 6.7 from being closed and high pressure to be generated when the hydraulic switching valve 4 is suddenly moved to the C position after the operation is completed, and also to provide a constant braking torque to the hydraulic motor 5 during the relief operation. It is. Also, check valves 9.9゛ are connected from the main return circuit lO to the oil passage 11 towards the oil passage 6.7.
The oil passage 6.
7. The internal hydraulic oil chamber of the hydraulic motor 5 is always filled with oil to prevent the hydraulic motor 5 from idling even when driven by an external force. Furthermore, each oil passage 6.7 is provided with a relief valve 12.12', which prevents abnormal confinement pressure from occurring in the operating circuit when the hydraulic switching valve 4 is in the C position. The set pressure is generally higher than the set pressure of the relief valve 8.8''.

On the other hand, the pressure oil of the biloft pump 3 is a pilot oil pressure source for operating the swing free valve 14, which will be described later, and the swing brake device 23.
It is used as a source of hydraulic pressure when the circuit is installed, and in order to maintain the circuit pressure at a constant value, it has a relief valve 18, a filter 20, and an oil passage 28.

Also, in the middle of the oil passages provided so as to communicate with the pair of oil passages 6.7, when the oil passage 6 becomes high pressure, the oil passage 7 on the low pressure side
There is a shuttle valve 13 that blocks the passage to the oil passage 6 on the low pressure side and allows the oil passage on the high pressure side to pass to the outlet port when the oil passage 7 becomes high pressure. Shuttle valve 1
The outlet port No. 3 is connected to the replenishment oil passage 11 by oil passages 30, 31, and 32 via an electromagnetic switching valve 15 and a swing free valve 14 (pilot switching valve). Oil road 30.31
The electromagnetic cutoff valve 15 located between the oil passages 31 and 32 has an internal oil passage opened and closed by a switch 22. In the pilot oil chamber of the swing free valve 14, in conjunction with the operating lever 25 of the hydraulic switching valve 4 for operating the hydraulic motor 5, when the operating lever 25 is in the neutral position, the internal electric circuit is opened and the valve is tilted forward or backward. The outlet port of the electromagnetic switching valve 16 which receives the electric signal of the limit switch 26 which closes the circuit via the electric wire 27 and opens and closes the internal oil passage is communicated with the oil passage 33. In addition, the oil passage 29 branched from the pilot oil pressure source oil passage 28 is
It communicates with the inlet port of the electromagnetic switching valve 16, and when the electromagnetic switching valve 16 is energized, the oil passages 29 and 33 are in communication, and when the energization is interrupted, the oil passage 29 is shut off, and the oil passage 33 is connected to the tank 21. It gets through.

The switch 22 is located at a position near the driver's seat where it can be easily operated, so that the electromagnetic switching valve 15 can be easily switched at the driver's will.

Next, the operation of the hydraulic/electrical circuit having the above configuration will be described in detail.

First, when the switch 22 is open and the electromagnetic switching valve 15 is not energized, the spool of the electromagnetic switching valve 15 is in the D position and the oil passages 30 and 31 are blocked, so the shuttle valve 13 is used to select The pressure oil on the high-pressure side of the oil passages 6.7 that has been removed does not flow into the supply oil passage 11, and therefore, the oil on the high pressure side of the oil passages 6.7 does not flow into the supply oil passage 11.
7 forms an independent circuit. In this state, the swing operation lever 25 is operated, the hydraulic switching valve 4 is placed in the A, B, or C position, and the hydraulic motor 5 is rotated forward or reverse, or decelerated against the inertia of the upper rotating body. When the hydraulic excavator is stopped or held at a stop, it maintains the swing hydraulic circuit state similar to that of the normal hydraulic excavator shown in Fig. 6 mentioned above.
Next, when the switch 22 is closed and the electromagnetic switching valve 15 is energized, the electromagnetic switching valve 15 is switched to the E position, and when the swing operating lever 25 is neutral, that is, when the limit switch 26 is open, the electromagnetic switching valve The spool 16 maintains the F position, the pilot oil chamber of the swing free valve 14 communicates with the tank 21, and the internal oil passage of the swing free valve 14 is open, so the hydraulic oil passage 6.7 of the hydraulic morph 5 are each
One pressure oil is connected to the outlet port of the shuttle valve 13, the oil passage 32,
It can freely flow into the other oil passage 7 or 6 via the swing free valve 14, the oil passage 31, the E position passage of the electromagnetic switching valve 15, the oil passage 30, and the check valve 9 or 9'. is capable of free rotation in either forward or reverse directions by external force.

From this state, when the operating lever 25 is tilted back and forth in an attempt to rotate the hydraulic motor 5 and the internal electric circuit of the limit switch notch 26 is closed, the electromagnetic switching valve 16 is energized.
Since the spool is switched from the F position to the 0 position, the pressure oil from the pilot pump 3 flows through the oil path 2g and 'rL magnetic switching valve 16.
The oil passes through the G position oil passage and the oil passage 33 into the pylon of the swing free valve 14 and into the oil chamber, and closes the internal oil passage of the swing free valve 14. As a result, the hydraulic oil passage 6.7 of the hydraulic motor 5
The hydraulic circuit returns to the same state as when the switch 22 was opened, and the hydraulic motor 5 starts to be activated by the pressure oil sent via the hydraulic switching valve 4. As the hydraulic motor 5 rotates, the upper rotating body with large inertia also rotates, and then, in order to stop it at a predetermined position, when the operating lever 25 is returned to the neutral position, the hydraulic switching valve 4 becomes the C position, and the hydraulic motor 5
At the same time, the internal electric circuit of the control lever 25 is linked to the operating lever 25, the internal electric circuit of the Mitsutwitch 26 is opened, and the electric &'' The spool is switched from the 0 position to the F position, the pressure oil sent from the pilot pump 3 through the oil path 29 is cut off, and the pyro 7) oil chamber of the swing free valve 14 is in the oil path 33, and the electromagnetic switching valve 16 is in the F position. Since it communicates with the tank 21 through the oil passage, the internal oil passage of the swing free valve 14 becomes open.

Therefore, the operating circuit of the hydraulic motor 5 has the same hydraulic circuit configuration as that during free rotation described above. As a result, the hydraulic morph 5 continues to rotate freely due to the inertia of the upper revolving structure and does not generate brake torque, so even when the attachment is hanging down as shown in FIG. 3, the tip of the attachment does not swing. Also, upper rotation with inertia.

To stop the body slowly, operate the swing operation lever gradually or intermittently in the direction of reverse swing, or move the swing control lever on the 5-axis of the swing motor as added to the hydraulic/electrical circuit diagram in Figure 1. A method may also be used in which a swing brake device 23 such as a hydraulic release type is provided and operated.

FIG. 5 is a hydraulic/electrical circuit diagram showing a second embodiment of the present invention, in which the operation for switching to the swing free circuit is performed using a hydraulic pilot method. That is, a pilot switching valve 15'' is used instead of the electromagnetic switching valve 15, a detent type two-position manual switching valve 22'' is used instead of the switch 22,
The hydraulic pressure source passes through an oil path 29 branched from the discharge side oil path 28 of the pilot pump 3 to the switching valve 22', and also to the switching valve 22'.
The outlet port of 2" and the pilot oil chamber of the pilot switching valve 15" are communicated by an oil passage.The operation method, operation, and effect of the second embodiment are completely the same as those of the first embodiment.

In addition, the switch 15 or the switching valve 15' that operates to switch to the free rotation circuit in the first embodiment and the second embodiment
It does not necessarily have to be a switching valve operated by electricity or hydraulics, and there is no problem even if it is a manually operated switching valve, as long as the switching operation position is in an easy-to-operate location near the driver's seat. .

Effects of the Invention If the swing hydraulic circuit according to the present invention is provided in the swing system of the upper rotating body of a hydraulic excavator, even if the front attachment is changed and the work content is different, the swing automatic brake can be maintained with the same machine. Both functions, such as the free turning function and the free turning function, can be selected freely by simply operating a switch near the driver's seat, allowing inexperienced drivers to perform the safest and most efficient work according to various work conditions. is also easy.

4. FiJ jtL explanation of the drawings Fig. 1 is a hydraulic/electrical circuit diagram showing the first embodiment of the present invention;
Figure 2 is a side view of the hydraulic hack hoe, Figure 3 is a side view when the front attachment of the hydraulic excavator is equipped with a crane, Figure 4 is a side view when the front attachment of the hydraulic excavator is equipped with a gripping tool, FIG. 5 is a hydraulic/electrical circuit diagram showing a second embodiment of the present invention, and FIG. 6 is a hydraulic circuit diagram of a conventional swing system for a hydraulic excavator.

3...Pilot pump 4...
... Hydraulic switching valve 8.8" ... Relief valve 9.9" ... Check valve 12.12" ... Relief valve 13 ... Shuttle valve 14 ......Swivel free valve (pilot switching valve)
15... Solenoid switching valve 15'... Pilot switching valve 22...
・・Switch 22°・・・・・Switching valve 25・・・・・Operation lever 26・・・・・Limit switch or more

Claims (1)

[Claims] In a swing drive system in which the hydraulic motor is rotated forward, reversed, or stopped by operating a manual operating lever and switching the hydraulic switching valve, and the rotating upper body is rotated by the rotational force, the pressure oil inflow/outflow port of the hydraulic motor is An oil passage is provided between a shuttle valve and a replenishment circuit that replenishes oil to the hydraulic oil passage leading to the hydraulic motor and an outlet port of the shuttle valve between the pair of hydraulic oil passages that communicate with each other, and an oil passage is provided between the oil passage The internal oil passage is normally open, and a pilot switching valve that is closed by pilot pressure and a switching valve that opens and closes the internal oil passage in response to an electric signal, hydraulic signal, or manual operation are arranged in series, and a hydraulic motor The oil passage from the pilot pump is opened by the electric signal from the limit switch, which is linked to the operating lever of the manual lever-operated hydraulic switching valve and closes the electrical circuit when the operating lever is not in the neutral position. A free turning system for a hydraulic excavator, characterized in that an oil passage is provided between an outlet port of a closed electromagnetic switching valve and a pilot oil chamber of the pilot switching valve.