JPH0762361B2 - Free excavator swivel system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic system capable of selectively performing free rotation of a hydraulically driven rotating body having a large inertial force.

Conventional technology By exchanging its front attachment, hydraulic excavators have been widely used not only as earthmoving machines such as backhoes and loading shovels, which are their original applications, but also as cargo handling machines with the characteristics of mobile cranes. In many cases, the function of the swing drive system for the upper swing structure imparted performance suitable for the most commonly used earthworking machines. That is, when the turning operation lever is returned from the turning position to the neutral position, a hydraulic circuit system is adopted in which the inertial energy of the turning structure is automatically absorbed by the hydraulic brake torque of the hydraulic motor to forcibly stop and hold. , It helps to improve the safety of earthwork and cycle time. An embodiment of this type of hydraulic circuit is as shown in FIG. 6, in which the turning motor 5 is operated by switching the hydraulic switching valve 4 for operating the turning hydraulic motor 5 to the A position or the B position in the figure. Rotates in the forward or reverse direction, and causes the upper revolving structure to revolve with a revolving pinion, a gear, or the like. When the hydraulic pressure switching valve 4 is set to the neutral position, that is, the C position during the turning operation, the pressure oil supply from the main pump 2 is cut off, and the oil passages 6 and 7 leading to the oil inflow and the outflow port of the turning motor 5 are cut off.
Are both closed by the spool of the hydraulic pressure switching valve 4, but the rotation inertia of the upper swing body causes the swing motor 5 to be forced to rotate, so that oil is sucked from one port and becomes high pressure in the other port. Is discharged from. The discharged high-pressure oil passes through the relief valve 8 ′ or 8 and is relieved in the low-pressure side oil passage 6 or 7, and is again sucked from the port on the opposite side of the hydraulic motor 5. By repeating this operation, the pressure oil is released from the relief valve 8,
While passing through 8'and becoming a low pressure, the rotational inertia energy of the upper swing body is gradually consumed, and the speed gradually decreases until it finally stops and holds its position. That is, when the hydraulic switching valve 4 is switched to the C position from the state where the upper swing body of the hydraulic excavator is swung, hydraulic braking torque is automatically generated in the hydraulic motor 5, and the swing speed of the upper swing body is reduced to a short time. The ability to stop in time is given. In order for the hydraulic motor 5 to generate braking torque, the oil chamber of the operating portion of the hydraulic motor 5 must be filled with oil, which leaks from the oil-tight portion during braking and the oil in the circuit is insufficient. Then, the braking torque cannot be exerted. Therefore, in order to prevent this, the oil passages 6 and 7 are prevented.
Is constantly replenished through the oil passage 11 of the main return circuit 10 from the swing motor and other actuators via the check valves 9 and 9 '. On the other hand, when the hydraulic switching valve 4 is in the neutral position C, nothing is done. Relief valves 12 and 12 'are provided to prevent the abnormal high pressures from being trapped in the oil passages 6 and 7 due to such a cause.

The above-mentioned hydraulic revolving upper revolving structure drive system is an advantage as an earthmoving machine or some cargo handling machines, but on the other hand, when changing the front attachment and using it for other purposes, it is necessary for work operation. Often there are disadvantages. For example, the boom 34 and the arm shown in FIG.
In a general hydraulic backhoe equipped with a backhoe bucket 36 and a backhoe bucket 36, the boom 34, the arm 35, and the backhoe bucket 36 are operated to scoop the earth and sand, and when the earth and sand are moved to a transport vehicle or a predetermined position, a swing operation The turning brake is automatically applied only by making the operation lever neutral, and it is easy to stop at a predetermined position.After the stop, even if the vehicle body is tilted to some extent, any operation is performed. It is effective because it is possible to maintain a fixed position for a short period of time. On the other hand, as shown in FIG. 4, the winch box 37 is attached to the tip of the arm 35, and the hook block 38 is hung by the wire rope 40. When the swing operation lever is returned to neutral, the winch box 37, which moves integrally with the upper swing body, tries to stop with a greater deceleration due to the swing braking force,
The suspended load 39 causes a pendulum motion due to the inertial force, and it is difficult to perform predetermined positioning. Conventionally, a skilled operator carefully and slowly accelerates and decelerates the turning of a machine equipped with such an attachment so that the pendulum motion does not occur on the suspended load 39, and A high degree of skill was required, such as stopping the swing by following the swinging motion in accordance with the pendulum movement of the load 39, or else the cycle time was reduced.

Also in the cargo handling work, as shown in FIG.
In a cargo handling machine of a type in which a wood or other gripping tool 42 is directly attached to the tip of the pendulum, pendulum motion is unlikely to occur even when a swing braking force is applied. Rather, forcibly stopping the swing improves the cycle time, It is easy to position.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As described above, when the front attachment of the hydraulic excavator is installed and used for various purposes, the swing braking force acts when the swing operation lever is neutralized depending on the work content. May be an advantage or a disadvantage. Therefore, in one hydraulic excavator, the automatic braking performance and the free turning performance when the turning lever is neutral can be freely selected by only a simple operation. It is intended to realize a hydraulic circuit system.

Means for Solving the Problems In order to realize the free turning system for the hydraulic excavator as described above, the present invention has taken the following means. That is, (a) the swing hydraulic motor is provided with a brake device capable of arbitrarily braking its output shaft system, and in the middle of an oil passage communicating a pair of operating circuits for supplying pressure oil to the hydraulic motor. A switching valve that opens the internal oil passage only when a signal acts on the receiving unit is provided.

B) Operation signal means for detecting that the hydraulic pressure switching valve for the hydraulic motor has been switched and outputting a switching signal is provided.

C) Switching means for interrupting the signal circuits before and after the switching means by an internal signal passage in the middle of the signal circuit leading to the receiving portion of the switching valve and only when the operation signal acts on the receiving portion. Select signal means capable of arbitrarily issuing a signal to the above-mentioned signal circuit through the above and stopping is provided.

When the operation selection signal means is operated to supply a signal to the signal circuit,
The signal reaches the switching means. At this time, if the swing motor hydraulic pressure switching valve is not operated, no signal is issued from the operation signal means and the switching means does not operate. Therefore, the signal circuits before and after the switching means are in a communicating state through the switching means, and the above selection is made. The signal from the signal means acts on the receiving portion of the switching valve, the internal oil passage of the switching valve is opened, and the pair of operating circuits to the hydraulic motor communicate with each other. Therefore, the hydraulic motor is free to apply an external force. Rotate to.

In this state, when the hydraulic pressure switching valve for the hydraulic motor is switched to either the forward or reverse direction, a signal acts from the operation signal means to the receiving portion of the switching signal means, and the signal from the selection signal means via the switching means. No longer acts on the receiving portion of the directional control valve, the internal oil passage of the directional control valve is closed, and the hydraulic motor and hydraulic directional control valve are connected by only one pair of operating circuits, and the swing start is normally performed. The turning acceleration is performed. In addition,
After the turning operation is started, when the turning operation lever is returned to the neutral position, the internal oil passage of the switching valve is opened again by the above-described operation, and the free turning state is established. In this free turn state, when stopping the turn, the turning lever is appropriately operated continuously or intermittently in the opposite direction, and especially when deceleration and precise selection are required. It is realized by adjusting the operation of the brake device on the output shaft system of the motor. When the signal from the selection signal means is stopped, the signal does not act on the receiving portion of the switching valve regardless of the presence or absence of the signal output from the operation signal means, and the turning system has the same circuit as a normal hydraulic excavator. Return to configuration.

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

FIG. 1 is a hydraulic / electrical circuit diagram showing a first embodiment when applied to a turning drive system of a hydraulic remote control type hydraulic excavator of the present invention.

Reference numeral 1 is an engine that drives a main pump 2 and a pilot pump 3. The main pump 2 sucks oil from a tank 21 through a suction strainer 19, and the discharge oil is regulated by a relief valve 17 to switch the hydraulic pressure for operating the swing motor 5. When the spool of the switching valve 4 communicates with the valve 4 and is in the neutral position, that is, when the spool is in the C position, it reaches another hydraulic switching valve (not shown) through the oil passage 24.
In addition to the return oil passage of another hydraulic switching valve group, the main return circuit
It becomes 10 and flows into the tank 21. Numerals 25 and 26 are pilot oil passages for introducing the signal pressure oil regulated by the turning operation pilot valve (not shown) into the pilot oil chamber of the hydraulic pressure switching valve 4. When the spool moves and switches to the A or B position, the discharge pressure oil of the main pump 2 is the oil passage 6, the hydraulic motor 5, the oil passage 7, and the hydraulic switching valve 4.
To the tank 21 via the A position passage 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 pressure switching valve 4 to the normal or reverse rotation of the hydraulic motor 5. To do. Reference numerals 8 and 8 ′ are relief valves which are opened toward the oil passages 6 to 7 and toward the oil passages 7 to 6, respectively, and the hydraulic excavator upper revolving structure having a large inertia is swung by the hydraulic motor 5. After that, when the hydraulic pressure switching valve 4 is suddenly moved to the C position, the oil passages 6 and 7 are closed to prevent a high pressure from being generated, and further, a constant braking torque is applied to the hydraulic motor 5 during the relief operation. is there. Further, since check valves 9 and 9'are provided to the oil passages 6 and 7 so as to replenish oil from the main return circuit 10 through the oil passage 11, the check valves 9 and 9'are respectively provided. The internal hydraulic oil chamber is constantly filled with oil so that the hydraulic motor 5 does not run idle even when driven by an external force. Further, the oil passages 6 and 7 are provided with relief valves 12 and 12 ', respectively, to prevent the occurrence of abnormal confining pressure in the operating circuit when the hydraulic pressure switching valve 4 is in the C position. The set pressure is generally higher than the set pressure of the relief valves 8 and 8 '.

On the other hand, the oil discharged from the pilot pump 3 serves as a pilot hydraulic pressure source, has a relief valve 18 for keeping the circuit pressure at a constant value, and is guided to the pilot valve through a filter 20 and an oil passage 28. ing.

Between the oil passages 6 and 7, there are provided a first second position and a pilot switching valve 13 that form an oil passage that shuts off both oil passages when no pilot pressure acts and forms an oil passage that communicates with each other when pilot pressure acts. The pilot oil chamber of the pilot switching valve 13 is in communication with the second position, the outlet port of the pilot switching valve 14, and the oil passage 31. In the pilot oil chamber of the pilot switching valve 14, when the pressure in either of the pilot oil passages 25 and 26 leading to the right or left pilot oil chamber of the hydraulic switching valve 4 rises, the pressure on that side is selectively taken out. A pilot oil passage 27 is led from the shuttle valve 16, and when the pressure in the pilot oil passage 27 rises, the pilot switching valve
14 switches to shut off the oil passage 30 that connects the outlet port of the electromagnetic switching valve 15 and the inlet port of the pilot switching valve 14,
When the pressure of the pilot oil passage 27 is lowered by passing 31 through the tank 21, the oil passage 30 and the oil passage 31 are communicated with each other.

Further, the inflow port of the electromagnetic switching valve 15 communicates with an oil passage 29 branched from the oil passage 28 of the pilot hydraulic pressure source, and by opening and closing the switch 22 attached to a position such as an operator's cab where it is easy to operate, The oil passage 30 is communicated with the tank 21 or the oil passage 29.

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

First, the case where the switch 22 is open and the electromagnetic switching valve 15 is not excited will be described. The spool of the electromagnetic switching valve 15 is H
Since the oil passage 29 is closed and the oil passage 30 is open to the tank 21, the spool position of the pilot switching valve 14 is F or G depending on the pressure of the pilot oil passage 27. However, the oil passage 31 communicates with the tank 21, so that the spool of the pilot switching valve 13 always holds the D position, and the oil passages 6 and 7 are cut off from each other. In this state, the turning operation lever is operated to set the hydraulic switching valve 4 to the A, B, or C position, and the hydraulic motor 5 is normally or reversely rotated or decelerated against the inertial force of the upper swing body. When holding or stopping and holding, the turning hydraulic circuit state similar to the normal hydraulic excavator of FIG. 6 described above is maintained. Next, the switch 22 is closed, and the electromagnetic switching valve 15
When the excitation switching valve 15 is excited, the switching valve 15 is switched to the I position, the turning operation lever is neutral, that is, when no signal pressure is generated in either of the pilot oil passages 25 and 26,
Since 14 is switched to the G position, the pressure oil from the pilot pump 3 is in the oil passage 29, the I position passage of the electromagnetic switching valve 15, and the oil passage 30.
To reach the inflow port of the pilot switching valve 14, and further through the G position passage and the oil passage 31 to reach the pilot oil chamber of the pilot switching valve 13 and switch the pilot switching valve 13 to the E position. , 7 are in communication with each other.
From this state, if the turning operation lever is operated to rotate the hydraulic motor 5 to increase the hydraulic pressure in the pilot oil passage 25 or 26, the hydraulic pressure switching valve 4 moves from the C position to A or B.
At the same time as switching to the position, the shuttle valve 16 takes out only the pressure signal of the pilot oil passage 25 or 26 on the side where the hydraulic pressure has risen, and passes through the pilot oil passage 27 to select the pilot switching valve.
14 pilot oil chamber, the pilot switching valve 14 F
Since the pressure is switched to the position, the pressure oil in the oil passage 30 is closed and the oil passage 31
Is connected to the tank 21 and the pilot oil chamber of the pilot switching valve 13 is at tank pressure, the pilot switching valve 13 is at position D, and the oil passages 6 and 7 are shut off, so that the hydraulic circuit state similar to that shown in FIG. 6 is restored. Then, the hydraulic motor 5 starts to be activated by the pressure oil sent via the hydraulic pressure switching valve 4. As the hydraulic motor 5 rotates, the upper revolving superstructure, which has a large inertia, also revolves and then stops at a predetermined position. Therefore, the revolving lever is returned to the neutral position, and the oil pressure in the pilot oil passages 25, 26 drops to the tank pressure. Then, the hydraulic switching valve 4 becomes the C position, stops the oil supply and discharge to the hydraulic motor 5, shuts off the ports communicating with the oil passages 6 and 7, and at the same time, the pressure in the pilot oil passage 27 also becomes the tank pressure. 14 becomes the G position, the pressure oil of the oil passage 30 flows into the pilot oil chamber of the pilot switching valve 13 through the G position passage of the pilot switching valve 14 and the oil passage 31, and switches the pilot switching valve 13 to the E position. Therefore, the oil passages 6 and 7 communicate with each other through the E position passage, the hydraulic motor 5 continues free rotation due to the inertia of the upper swing body, and no brake torque is generated. Therefore, the attachment as shown in FIG. 4 is suspended. When even shake does not occur load at the tip. To slowly stop the upper revolving superstructure with inertia, operate the revolving operation lever gradually or intermittently in the reverse revolving direction, or as described in the hydraulic / electric circuit diagram of Fig. 1. In addition, a turning brake device 23 such as a hydraulic release type provided on the turning motor 5 axis may be provided and operated.

FIG. 2 is a hydraulic / electrical circuit diagram showing a second embodiment of the present invention. As with the first embodiment, the hydraulic switching valve for operating the hydraulic motor 5 is a hydraulic pilot type.

In this embodiment, instead of the pilot switching valve 14, an electromagnetic switching valve 14 'is used, and the signal pressure sent from the shuttle valve 16 is guided to a pressure switch 33 which is closed when the pressure rises, and the pressure switch 33 The electromagnetic switching valve 14 'is actuated by the electric signal of 1., and the flow and operation / operation of the pressure oil in this circuit are exactly the same as in the first embodiment.

The shuttle valve 16, the pilot switching valves 14 and 14 ', the electromagnetic switching valve 15, and the switch 22 in each of the above-described embodiments are not necessarily limited to these.
The shuttle valve 16 may be operation signal means for outputting a signal indicating that the swing hydraulic switching valve has been switched, and the pilot switching valves 14, 14 'are switching means for opening and closing the signal circuit by a signal from the operation signal means. Electromagnetic switching valve 1
5. The switch 22 is a selection signal means capable of arbitrarily transmitting and stopping a signal that can be remotely operated from the driver's seat or the like, and the result of the present invention can be obtained. In short, the present invention is not limited to the above-mentioned embodiment. It is possible to make various design modifications, for example, to those having different operation systems of the hydraulic switching valve for the swing hydraulic motor without departing from the spirit of the above.

EFFECTS OF THE INVENTION If the system according to the present invention is provided as a turning system for a hydraulic excavator, even if the front attachment is changed and the work content is changed, a hydraulic automatic braking function and a free turning function for turning with the same machine are provided. Any function, such as the mechanical brake function, can be
Since the selection can be easily made freely, it is easy for a driver who is not accustomed to the safest and most efficient work according to various work conditions with one hydraulic excavator.

[Brief description of drawings]

FIG. 1 is a hydraulic / electrical circuit diagram showing a first embodiment of the present invention,
FIG. 2 is a hydraulic / electrical circuit diagram showing a second embodiment of the present invention,
Fig. 3 is a side view of the hydraulic backhoe, Fig. 4 is a side view of the front attachment of the hydraulic excavator equipped with a crane, and Fig. 5 is a side view of the front attachment of the hydraulic excavator mounted. FIG. 6 is a hydraulic circuit diagram of a swing system of a conventional hydraulic excavator. 3 ... Pilot pump 4 ... Hydraulic switching valve 8,8 '... Relief valve 9,9' ... Check valve 13,14 ... Pilot switching valve 14 ', 15 ... Electromagnetic switching valve 16 ... Shuttle valve 22 ...... Switch 33 …… Pressure switch

Claims (1)

[Claims] 1. A pair of oil passages communicating with a turning hydraulic motor,
Supply the pressure oil from the hydraulic switching valve to rotate the hydraulic motor forward,
In a revolving drive system configured to reverse and stop, a brake device capable of arbitrarily braking the output shaft system of the hydraulic motor, an oil passage communicating with the pair of oil passages, and an intermediate portion between the oil passages. Provided Normally, the internal oil passage is closed, but when a signal acts on the receiving part, the switching valve that opens the internal oil passage and the hydraulic motor hydraulic switching valve are detected and the switching signal is output. When the operation signal provided in the middle of the signal circuit communicating with the signal receiving unit and the signal receiving unit of the switching valve acts on the signal receiving unit, it connects the signal circuit before and after the signal circuit through the internal signal passage, and the switching unit. A free turning system for a hydraulic excavator comprising selection signal means capable of arbitrarily transmitting / stopping a signal to / from the above-mentioned signal circuit via the above.