JPH0549771B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a hydraulic system that can selectively freely rotate a hydraulically driven rotating body with a large inertial force.

Conventional Technology Hydraulic excavators have traditionally been used by replacing their front attachments, allowing them to be used not only as earthmoving machines such as backhoes and loading shovels, which are their original uses, but also as cargo handling machines with the characteristics of mobile cranes. Although often widely used, the functionality of the swing drive system of the upper revolving structure has given it performance suitable for the most commonly used earth-moving machines. In other words, when the swing operation lever is returned from the swing position to the neutral position, a hydraulic circuit system is adopted in which the inertia energy of the swing body is automatically absorbed by the hydraulic brake torque of the hydraulic motor, and the system is forcibly stopped and held. , which helps improve the safety and cycle time of earthwork operations. 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 swing operation, the pressure oil supply from the main pump 2 is cut off, and the swing motor 5
The oil passages 6 and 7 leading to the oil inflow and oil outflow ports are both closed by the spool of the hydraulic switching valve 4, but since the swing motor 5 is forcibly rotated due to the rotational inertia of the upper swing structure, one Oil is sucked in through a port and discharged under high pressure from the other port. The discharged high-pressure oil passes through the relief valve 8' or 8, is relieved to the oil passage 6 or 7 on the low-pressure side, 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 valves 8, 8' and becomes low pressure, the rotational inertia energy of the upper revolving body is consumed, the speed gradually decreases, and finally it stops and maintains its position. It becomes like this. That is, when the hydraulic switching valve 4 is switched to the C position while the upper rotating body of the hydraulic excavator is being rotated, hydraulic braking torque is automatically generated in the hydraulic motor 5, reducing the swinging speed of the upper rotating body and shortening the rotation speed of the upper rotating body. It has been given the ability to stop in time. In addition, in order for the hydraulic motor 5 to generate braking torque, the oil chamber of the operating part of the hydraulic motor 5 must be filled with oil, and oil may leak from the oil-tight part during braking, causing a lack of oil during rotation. In this case, braking torque cannot be exerted, so in order to prevent this, oil from the main return circuit 10 from the swing motor and other actuators is supplied to the oil passages 6 and 7 via the check valves 9 and 9' through the oil passage 11. Relief valves 12 and 12' are provided to prevent abnormally high pressure from being trapped in the oil passages 6 and 7 for some reason when the hydraulic switching valve 4 reaches the neutral position C. be.

The above-mentioned upper revolving body drive system with a hydraulic circuit configuration has advantages when used as an earth-moving machine or some cargo handling machines, but on the other hand, when changing the front attachment and using it for other purposes, it becomes difficult to operate. This often results in operational disadvantages. For example, in a general hydraulic backhoe equipped with a boom 34, an arm 35, and a backhoe bucket 36 shown in FIG. 2, the boom 34, arm 35, and backhoe bucket 36 are operated to scoop up earth and sand and rotate. When moving earth and sand to a transport vehicle or a predetermined location, the swing brake is automatically applied by simply setting the swing operation lever to neutral, making it easy to stop at a predetermined location. Even if the device is tilted to a certain degree, it is effective because it can maintain a fixed position for a short period of time without any operation. On the other hand, as shown in Figure 3, arm 3
5, a winch box 37 is attached to the tip of the hook block 38 by a wire rope 40, and when handling a suspended load 39, the suspended load 39 is hoisted, the upper revolving structure is rotated to move it to a predetermined position, and the When the operating lever is returned to neutral,
The winch box 37, which moves integrally with the upper rotating body, attempts to stop with a large deceleration due to the swing braking force, and the suspended load 39 causes a pendulum movement due to inertia, making it extremely difficult to position it at a predetermined position. Conventionally, a machine equipped with such an attachment has been operated by a skilled operator who carefully accelerates and decelerates the swing slowly to prevent pendulum movement from occurring in the suspended load 39. A high degree of skill is required to follow the swinging motion of the suspended load 39 in accordance with the pendulum motion and to stop the swinging, otherwise the cycle time would be reduced.

Also, in cargo handling work, as shown in Figure 4,
In a cargo handling machine in which a gripping tool 42 of wood or other material is directly attached to the tip of the arm 41, pendulum movement is unlikely to occur even when a swing brake force is applied, and it is better to forcibly stop the swing to a certain extent 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, depending on the work involved, when the swing operation lever is set to neutral, the swing brake force may vary. The effect may be an advantage or a disadvantage, so
The present invention aims to realize a hydraulic circuit system in which automatic braking performance when the swing operation lever is in the neutral state and free swing performance can be freely selected with a simple operation in one hydraulic excavator.

Means for Solving the Problem In order to provide the above functions, the present invention has the following hydraulic/electrical circuit configuration.

That is, there is a shuttle valve between a pair of hydraulic oil passages connected to the pressure oil inflow and outflow ports of the hydraulic motor, and an oil supply circuit that communicates from the outlet port of the shuttle valve to the oil replenishment circuit to the hydraulic oil passage of the hydraulic motor. constitute a road. In the middle of the oil passage, there is a pilot switching valve (hereinafter referred to as a swing free valve) which normally keeps the internal oil passage open but is closed by pilot pressure, as well as an electric signal and hydraulic pressure. A switching valve is provided to open and close the internal oil passage by signal or manually. In addition, the pilot oil chamber of the above-mentioned pilot switching valve is connected to the operating lever of the manually operated lever type hydraulic switching valve for operating the hydraulic motor, and the electric circuit is opened 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 electrical signal.

Function The switching valve located in the middle of the communication oil path between the outlet port of the shuttle valve provided between a pair of hydraulic motor hydraulic oil paths and the oil replenishment circuit is switched to the open state by an electric signal, hydraulic signal, or manually. do.

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 electromagnetic switching valve is not energized and the internal oil passage receives pressure from the pilot pump. The oil is shut off and no pressure oil is supplied to the pilot oil chamber of the swing free valve, so it remains open, and one oil path of the hydraulic motor operating oil path is connected to the shuttle valve, free swing valve, switching valve, and replenishment circuit. It communicates with the other hydraulic motor hydraulic oil passage through the check valve for the hydraulic motor. 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 limit switch linked to the swing operation lever is closed, that is, when the swing operation is started, the solenoid switching valve is energized, and the pressure oil from the pilot pump passes through the internal oil path of the solenoid valve and rotates. The oil flows into the pilot oil chamber of the 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, so when the swing motor operates, normal swing is performed. acceleration is achieved. 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 motor hydraulic oil passages become independent regardless of the position of the operating lever for operating the hydraulic motor. This results in a circuit similar to that of the normal hydraulic excavator swing system shown in FIG.

Embodiments Examples of the present invention will be described with reference to the drawings.

FIG. 1 is a hydraulic/electric field circuit diagram showing an embodiment of the present invention. Reference numeral 1 is an engine that drives a main pump 2 and a pilot pump 3, which sucks oil from a tank 21 through a suction strainer 19, and discharges oil. The pressure is regulated by the relief valve 17 and communicates with the manually operated lever type hydraulic switching valve 4 for operating the swing motor 5. When the operating lever 25 of the switching valve 4 is in the neutral position, that is, in the C position, the pressure oil is in the C position open oil state. It passes through the oil passage and oil passage 24 to reach another hydraulic switching valve (not shown), and further merges with the return oil passage of the other hydraulic switching valve group to form the main 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. To the tank 21 via the A position passage of the hydraulic switching valve 4, or to the tank 21 via the oil passage 7, the hydraulic motor 5, the oil passage 6, and the B position passage of the hydraulic switching valve 4.
The hydraulic motor 5 functions to rotate forward or reverse. 8, 8' are respectively from oil passage 6 to 7,
This is a relief valve that opens from oil passages 7 to 6, and after the hydraulic excavator upper rotating body with large inertia is rotated by the hydraulic motor 5, the hydraulic switching valve 4 is suddenly set to the C position. When the oil passages 6 and 7 are closed, high pressure is prevented from being generated.
Furthermore, it is used to apply a constant braking torque to the hydraulic motor 5 during the relief operation. Also oil line 6,
Since the check valves 9 and 9' are provided in the direction of replenishing the main oil from the main return circuit 10 through the oil passage 11, the oil passages 6 and 7 and the hydraulic motor 5
The internal hydraulic oil chamber is always filled with oil to prevent the hydraulic motor 5 from idling even when driven by an external force. Furthermore, the oil passages 6 and 7 are provided with relief valves 12 and 12', respectively, to prevent 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 valves 8, 8'.

On the other hand, the pressure oil of the pilot pump 3 is used as a pilot hydraulic pressure source for operating the swing free valve 14 (described later), an operating hydraulic pressure source when a swing brake device 23 is installed, and other purposes, and maintains the circuit pressure at a constant value. For this purpose, it has a relief valve 18, a filter 20, and an oil passage 28.

In addition, when the oil passage 6 becomes high pressure, there is
A shuttle that blocks the passage to the oil passage 7 on the low pressure side, and when the oil passage 7 becomes high pressure, 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 through the outlet port. A valve 13 is provided, and an outlet port of the shuttle valve 13 is connected to the supply 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 3
The electromagnetic switching valve 15, which is located between 0 and 31, has an internal oil passage opened and closed by a switch 22, and is located between oil passages 31 and 32. 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 a neutral position, the internal electric circuit is opened and the valve is tilted forward or backward. An oil passage 33 communicates with an outlet port of an electromagnetic switching valve 16 which receives an electric signal from a limit switch 26 which closes the circuit via an electric wire 27 and opens and closes an internal oil passage. An oil passage 29 branched from the pilot oil pressure source oil passage 28 communicates with the inlet port of the electric switching valve 16, and when the electromagnetic switching valve 16 is energized, the oil passages 29 and 33 are in communication with each other, and when the energization is interrupted, the oil passage 29 is connected to the inlet port of the electric switching valve 16. Oil road 29
is blocked, and the oil passage 33 communicates with the tank 21.

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, the solenoid switching valve 1
5 is not excited, the spool of the electromagnetic switching valve 15 is in the D position, and the oil passages 30, 31
is shut off, so that the pressure oil on the high pressure side of the oil passages 6 and 7 selected by the shuttle valve 13 does not flow into the supply oil passage 11, and therefore the oil passages 6 and 7 form 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 moved or held at a stop, the swing hydraulic circuit state is maintained similar to that of the conventional hydraulic excavator shown in FIG. 6 described above. Next, switch 22
When the circuit is closed and the electromagnetic switching valve 15 is energized, the electromagnetic switching valve 15 is switched to the E position, and the swing operation lever 2
5 is neutral, that is, when the limit switch 26 is open, the spool of the solenoid switching valve 16 is in the F position.
The position is maintained, 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 passages 6 and 7 of the hydraulic motor 5 are connected to one side, respectively. Pressure oil is connected to the exit port of the shuttle valve 13, the oil passage 32, and the swing free valve 1.
4. It can freely flow into the other oil passage 7 or 6 via 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';
The hydraulic motor 5 can freely rotate 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 26 is closed, the electromagnetic switching valve 16 is energized and the spool is switched from the F position to the G position. Pressure oil from the pilot pump 3 flows into the pilot oil chamber of the swing free valve 14 through the oil path 29, the G position oil path of the electromagnetic switching valve 16, and the oil path 33, and flows through the internal oil path of the swing free valve 14. Close the circuit. As a result, the hydraulic oil passages 6 and 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 switching valve 4 switches to the C position. At the same time, the oil supply and discharge are stopped and the ports leading to the oil passages 6 and 7 are shut off, and the internal electric circuit of the limit switch 26 linked to the operating lever 25 is opened, and the spool of the electromagnetic switching valve 16 is moved from the G position to the F position. As a result, the pressure oil sent from the pilot pump 3 through the oil path 29 is cut off, and the pilot oil chamber of the swing free valve 14 communicates with the tank 21 through the oil path 33 and the F position oil path of the electromagnetic switching valve 16. Therefore, 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 motor 5 continues to rotate freely due to the inertia of the upper rotating body and does not generate brake torque, so the third
Even when hanging the attachment as shown in the figure,
No load swing occurs at the tip. In addition, to slowly stop the rotating upper structure with inertial force, operate the swing operation lever gradually or intermittently in the direction of reverse rotation, or use the hydraulic/electrical circuit shown in Figure 1. Similarly, a method may be adopted in which a swing brake device 23 of a hydraulic release type or the like provided on the five axes of the swing motor 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 by a hydraulic pilot system. That is, the pilot switching valve 1 is used instead of the electromagnetic switching valve 15.
5', a detent type two-position manual switching valve 22' is used in place of the switch 22, and the oil pressure source is sent to the switching valve 22' via an oil path 29 branched from the discharge side oil path 28 of the pilot pump 3. Further, the outlet port of the switching valve 22' and the pilot oil chamber of the pilot switching valve 15' are communicated through an oil passage. In the second embodiment as well, the operation method, action, and effect are the same as in the first embodiment.
This is exactly the same as the example.

Note that the switch 15 or switching valve 15' that operates to switch to the swing-free circuit in the first and second embodiments does not necessarily have to be an electrically or hydraulically operated switching valve, but may be in a position where the switching operation is possible. As long as it is located near the driver's seat and is easy to operate, there is no problem even if it is a manually operated switching valve.

Effects of the Invention If the swing hydraulic circuit according to the present invention is installed 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 system can be automatically rotated with the same machine. Both the brake function and free turning function can be freely selected by simply operating a switch near the driver's seat, so it is the safest and most convenient option to suit various work conditions.
Moreover, efficient work is easy even for inexperienced drivers.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic and electrical circuit diagram showing a first embodiment of the present invention, Fig. 2 is a side view of a hydraulic backhoe, and Fig. 3 is a side view of a hydraulic excavator with a crane attached to its front attachment. , Fig. 4 is a side view of the front attachment of a hydraulic excavator with a grip attached to it, Fig. 5 is a hydraulic/electrical circuit diagram showing the second embodiment of the present invention, and Fig. 6 is a diagram of a conventional hydraulic excavator. FIG. 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.

Claims (1)

[Claims] 1 In a swing drive system in which a hydraulic switching valve is switched by an operating means to operate a hydraulic motor and the rotating upper body is rotated by the rotational force thereof, a pair of hydraulic oil passages leading to pressure oil inflow and outflow ports to the hydraulic motor. A shuttle valve installed in the middle of an oil path communicating with
An oil passage connecting the outlet port of the shuttle valve and a supply circuit to the hydraulic motor operating oil passage is provided in series in the middle of the oil passage, and when a signal acts on the receiving section, the normally open internal oil passage is closed. A first switching valve and a second valve that opens and closes the internal oil passage according to an arbitrary signal from the outside.
A free turning hydraulic excavator comprising: a switching valve; and signal means for detecting that the switching valve is in a position other than neutral and supplying a signal to a receiving section of the first switching valve. Hydraulic circuit.