JPH01235736A - Control stabilizing circuit for traveling vibration of wheeled construction machine - Google Patents

Abstract

PURPOSE:To prevent the useless vertical movement of working machine by a method in which a branch tube is set between a vibration suppressor and the first closing valve, the pipeline is provided with a switching valve and the second closing valve and connected to an oil-pressure pump, and these valves are connected to a relay circuit. CONSTITUTION:A branch tube 30' is set between a vibration suppressor 20 and the first closing valve 17, and the pipeline is provided with a switching valve 35 and the second closing valve 34 in series and connected to an oil- pressure pump 11. The closing valves 17 and 34 are connected to a relay circuit 1 with a switch, and the switching valve 35 is connected to the circuit 1 through a flow rate-detecting valve 4. When operating the suppressor 20 by the switch 6 and oil-pressure switching valves 12 and 13, where the closing valve 17 is at B-position, the pressure of a lift cylinder 8a is equalized with that of an accumulator 19. The useless vertical movement of the working machine during switching period can thus be prevented, ensuring safe operations.

Description

[Detailed Description of the Invention] Industrial Application Field This invention provides a system in which a base end of a working device protruding from a vehicle body is pivoted to the vehicle body so as to be movable up and down, and a hydraulic vibration suppression device is also provided. The present invention relates to a circuit that can automatically prevent the work equipment from descending under its own weight when switching between activation and deactivation of a running vibration prevention device in a non-shocked, wheel-type construction machine supported by a hydraulic cylinder.

Conventional technology Conventionally, a vibration suppressing device is installed in the load side circuit of a hydraulic cylinder that supports a working device that protrudes from the vehicle body of a wheeled construction machine, so that it can be opened and closed by a switching valve, and vibration is generated. The vibration suppression device was operated only while the vehicle was running, intervening in the load-side conduit of the hydraulic cylinder.

For example, as a representative example of a wheeled construction machine, a wheeled tractor-shovel as shown in FIG. Therefore,
When a wheeled tractor excavator travels on an uneven road surface, the working device 7 protrudes further forward than the front axle, and its weight ratio is large.The axle is non-shocked and is supported entirely by rubber tires. Vibration is likely to occur.

In order to absorb the vibration energy at this time and make it a damped vibration, the pipe line 15QL on the load side of the lift cylinder 8 that supports the working device 7 is connected to a slow return valve 18 consisting of a throttle valve 18α, a check valve 1B4, and an accumulator 19. The working device 7 is vibrated separately from the vehicle body by communicating with the vibration suppressing device 20 constituted by the vibration suppressing device 20 through the one-branch pipe 16, leading to damped vibration.

On the other hand, the wheeled tractor excavator does not only travel, but also lowers the bucket of the working device 7 to the ground, uses the forward force of the machine to sink the cutting edge into the earth and sand, fills the bucket with earth and sand, and lifts it up with the tamp cylinder 9. In many cases, the entire work device 7 is lifted up by the lift cylinder 8, adjusted to an appropriate height at another point, and the dump cylinder 9 is operated again to dump the earth and sand. The traveling speed during loading and dumping in such excavation and loading operations is extremely low or at a standstill, and vibrations do not occur; rather, the packets are held integrally with the vehicle body. If not, accurate and safe work cannot be performed, so in such a case, the lift cylinder 8 must be isolated from the vibration suppressor 20, but on the other hand, it must be in communication with the vibration suppressor 20 when traveling. desirable.

Therefore, a switching valve 17 is interposed in the middle of a branch pipe 16 that communicates a pipe 15α leading to the head side oil chamber 8 cL, which is the load side of the lift cylinder 8, and the vibration suppressing device 20, and a switch is installed near the driver's seat. 6 was being operated selectively.

During a series of operations such as digging, moving, loading, and moving during work, the invention must be carried out at least twice, and more times depending on the distance traveled, the road surface, and obstacles. Moreover, the opening and closing operations of the communication between the lift cylinder and the vibration suppression device become frequent. To specifically describe the situation at this time, when loading earth and sand into the bucket of the working device 7, the switch 6 is opened and the on-off valve 17 is placed in position A in Fig. 3.
The conduit 15α and the vibration suppression bag δ20 are isolated. In this state, when the bucket is loaded with earth and sand and the working device 7 is raised, the circuit pressure in the head side oil chamber 8α of the lift cylinder 8 becomes high in proportion to the load on the bucket. Next, when the excavation of the earth and sand is completed and the travel is started, the switch 6 is closed to connect the vibration suppression circuit 20 and the pipe line 15 (l) to suppress vibrations during the travel, and the accumulator 19 Since the pressure in the pipe 15α is not accumulated in the pipe 15α, a part of the pressure oil in the head side oil chamber 8α of the lift cylinder 8 is transferred to the pipe 15α, the branch pipe 16, the B position passage of the on-off valve 17,
As the water flows into the accumulator 19 through the slow return valve 18, the working device 7 is lowered relative to the vehicle body. Also,
After the next move, when dumping earth and sand at a predetermined location, in order to prevent the vehicle from shaking, the switch 6 is opened again to cut off the communication between the conduit 15α and the vibration suppression device 20, and the dump cylinder 9 to release the dirt from the bucket. As a result, the load on the working device 7 is reduced and the conduit 15
The pressure at α decreases accordingly. If the vehicle starts moving from this state, or if the switch 6 is closed and the lift cylinder 8 is communicated with the vibration suppression circuit 20 while the vehicle is running, in order to suppress the vibration of the vehicle, the accumulator 19 is Because the high pressure in the head side oil chamber 8α corresponding to the load of 8α, resulting in the working device 7 being raised relative to the vehicle body.

In this way, each time the on-off valve 17 is switched to the B position, the working device 7 moves slightly up and down against the driver's will, making it difficult to maintain the accurate bucket position required during work. , impeding speedy and safe work.

In view of this problem, the present invention maintains the pressure in the head side oil chamber of the lift cylinder and the accumulated pressure in the accumulator at the same level when switching to the vibration suppression circuit state, thereby causing unnecessary up and down movement of one working device or the vehicle body. The purpose is to provide a stabilizing circuit that prevents rotation.

Means for Solving the Problems In order to solve the above problems, the present invention takes the following measures. Namely.

b) The branch pipe of the discharge pipe of the hydraulic pump for working equipment,
The branch pipe is connected between the vibration suppressing device and the first on-off valve that opens and closes, leading to the load-side oil chamber of the hydraulic cylinder that supports the work equipment. The branch pipe is connected to the flow rate detection valve by the biasing force of a built-in spring, or the receiving part is connected to the pressure held in the vibration suppressor, that is, by the accumulator storage. A switching valve is provided in series, which switches when a pressure higher than the pressure is applied, cuts off the connection to the flow rate detection valve, and introduces pressure oil from the hydraulic pump into the vibration suppression device via a branch line.

c) A power source is connected to the receiving part of the first on-off valve via a switch, a limit switch operated by the flow rate detection valve, and a make contact operated by the limit switch and having a holding function.

2) The receiving part of the second on-off valve includes the above switch and the first
The power supply is connected through a break contact that opens the internal electrical circuit only when the receiving part of the on-off valve is energized.

e) Pressure oil from a pipe line leading to the load-side oil chamber of the hydraulic cylinder that supports the working device is introduced to the receiving portion of the switching valve through a pilot pipe line.

Operation When a load is applied to the work equipment and the work equipment starts running, the switch is closed and the work equipment is set in the running position, and the power is applied to the receiving part of the second on-off valve via the switch and the flake contact. , the second on-off valve opens and supplies pressure oil from the hydraulic pump to the switching valve. At this time, since the load side pressure of the hydraulic cylinder for supporting the working equipment is acting on the receiving part of the switching valve, this pressure is higher than the pressure in the vibration suppression device, so the hydraulic pump passes through the switching valve. Pressure oil flows into the vibration suppression device. As a result, the pressure inside the vibration suppression device rises, and when it becomes approximately equal to the load side pressure of the hydraulic cylinder, the switching valve is switched, and the pressure oil flows into the flow rate detection valve and the limit switch. , the make contact is energized, the power source is connected to the receiving part of the first on-off valve, and the first on-off valve is opened and connected to the load-side oil chamber of the hydraulic cylinder supporting one working device. The first opening/closing operation is performed after the pressures in the oil chamber of the hydraulic cylinder and the vibration suppression device become approximately the same as described above. There is no instantaneous lowering of the working equipment when the valve opens.

Note that at the same time that the receiving part of the first on-off valve is energized, the break contact is also energized, the power to the receiving part of the second on-off valve is cut off, the branch pipe is closed, and the flow rate detection pulp is turned on. The pressure oil inflow stops and the limit switch becomes inoperable, or the make contact has a holding function, so unless the switch is opened, power will continue to be supplied to the receiving part of the first on-off valve. be done.

Example Embodiments of the invention will be described based on the drawings.

FIG. 1 is an electrical/hydraulic system diagram when a wheeled tractor excavator, which is a typical example of a wheeled construction machine, is equipped with a normal vibration suppression device and a running vibration suppression stabilization circuit according to the present invention.

In the figure, 8 and 9 are lift cylinders and dump cylinders for working equipment, 1O is a tank, 11 is a hydraulic pump for operating working equipment in a hydraulic power unit, and 12 is a hydraulic switching valve for the dump cylinder 9. The head side oil chamber 9α and the rod side oil chamber 9bi of the dump cylinder 9 are connected to the switching valve 12 via pipes 14α and 146, and 13 is a hydraulic switching valve for the lift cylinder 8;
The head side oil chamber 8α and the rod side oil chamber 8a of the lift cylinder 8 are connected to each other via pipes 15c and 15d. Further, in the lift cylinder 8, a pipe line 1 connected to the oil chamber on the load side by the working device, that is, the oil chamber on the head side 8α.
A branch pipe 16 is provided in the middle of 5α, and this branch pipe 16 is connected via a first on-off valve 17 to a slow return valve 18 consisting of a throttle valve 18α and a check valve 18. 18 is further connected to an accumulator 19. The on-off valve 17 normally closes the branch pipe 16 by the biasing force of a built-in spring, and opens when an electric signal is input to its receiving section, opening the branch pipe 16.
It communicates with a vibration suppression device 20 consisting of a slow return valve 18 and an accumulator l9'.

Further, as the accumulator 19, a bladder type accumulator is usually used, and depending on the load size, work conditions, installation space, etc., one or more may be used, or one or more may be used including the on-off valve 17 and the vibration suppressor 20. They may also be used in various combinations.

Note that 21 is a main relief valve, 22, 23 and 24 are overload relief valves of circuits communicating with the pipes 14α, 144, and 15α, respectively, and 25, 26, 27, and 28 are check valves for preventing cavitation.

Moreover, the pressure oil of the hydraulic pump 11 is
A branch pipe 30, 30' is provided in the middle of the pipe that flows into the hydraulic switching valve group consisting of the hydraulic switching valve group, and the branch pipe 30' is provided with a check valve for backflow prevention between the vibration suppressor 20 and the on-off valve 17. 36, and the conduit 30 is connected in series with an on-off valve 34,
A switching valve 35 is provided. This on-off valve 34 is normally in the C position and closes the pipe line 30 due to the biasing force of a built-in spring, but when an electric signal is applied to the receiving section via the electric wire 32, it is switched to the D position and the pipe line 30 is closed. Route 30 is opened.

Also, the switching valve 35 is normally in the E position due to the biasing force of the built-in splinter, allowing the pipe line 30 to pass through the pipe line 37, or receiving pressure oil in the pilot pipe line 31 communicating with the pipe line 15α. When the pressure is higher than that of the line 30', the switch is switched to the F position, and the passage from the line 30 to the line 37 is blocked, and the lines 30 and 30' are in communication.

4 is a flow detection valve, which has two left and right oil chambers formed by the piston α supported by a spring for maintaining neutrality, each of which communicates with the pipe 37 and the tank IO, and both left and right sleeve chambers are connected to the inside of the piston α. The piston Q moves to the right in the figure when there is a flow of pressure oil from the pipe line 37 toward the tank IO, and when the flow of pressure oil stops, the piston Q moves to the right in the figure. The piston α gradually returns to the neutral position. Reference numeral 5 designates a limit switch, which is provided at a position where the electric wire 33 is normally open, or when the piston α of the flow rate detection valve 4 moves to the right, it acts on the actuator of the limit switch 5 and closes the electric wire 33. .

Further, l is a relay circuit having a make contact 2, a break contact 3, a switch 6 for opening and closing the power supply, etc., and the make contact 2 is normally open, or when the switch 6 is closed, it is activated by the limit switch 5. Once the electric wire 33 is closed, power is continued to be supplied to the electric wire 29 leading to the receiving part of the on-off valve 17, and this state is maintained unless the switch 6 is opened, and the break contact 3 is normally closed. This is an electrical circuit of the known technology, which is designed to be open while the electric wire 29 is energized, regardless of whether the limit switch 5 is open or closed.

Next, the operation of the invention having the above configuration will be explained.

When stopping the wheeled tractor excavator or performing earth and sand excavation or scooping work at extremely low speeds, operate the hydraulic selector valves 12 and 13 for operating the work equipment 7 while keeping the switch 6 open to perform the required operation. However, at this time, since no electrical signal is acting on the receiving section of the on-off valve 17.34, both positions A and C, which are closed circuits, are maintained.

Therefore, the working device 7 is reliably supported by the lift cylinder 8 with respect to the vehicle body, and operates accurately in accordance with the operation of the hydraulic switching valves 12, 13, as in a normal machine.

After completing the scooping of earth and sand into the bucket and starting traveling on the undulating transportation road, first close the switch 6 and then operate the hydraulic selector valves 12 and 13 to adjust the traveling posture. The power passes through the switch 6, the break contact 3, and the electric wire 32, and acts on the receiving part of the on-off valve 34, so that the on-off valve 34 is switched from the C position to the D position, causing the pipe line 30 to pass through the switching valve 35. . On the other hand, the receiving part of the switching valve 35 has a conduit 15 connected to the head side oil chamber 8α of the lift cylinder 8.
The pilot pipe 31 is led from α, but since this pressure has increased due to the load after enclosing the earth and sand, the switching valve 35 is already in the F position, and the pressure in the pipe 30 is The oil flows into the accumulator 19 via the D position oil passage of the on-off valve 34, the F position oil passage of the switching valve 35, the check valve 36, the pipe 30', and the slow return valve 18, or When the accumulated pressure increases and becomes approximately equal to the pressure in the pilot pipe 31, that is, the pressure in the head side oil chamber 8α, the switching valve 35 is switched from the F position to the E position by the return force of the built-in spring. As a result, the pressure oil in the pipe line 30 passes through the E position oil line of the switching valve 35 and the pipe line 37, flows into the oil chamber on the left side of the flow rate detection valve 4, and moves the piston α to the right. As a result, the limit switch 5 is activated, and the electric wire 33 is brought into a closed circuit state. Accordingly, the power that has passed through the switch 6 excites the make contact 2 via the limit switch 5, so that the make contact 2 is closed, and the receiving part of the on-off valve 17 is energized through the electric wire 29. The on-off valve 17 is switched from the A position to the B position,
The pipe line 16 communicates with the accumulator 19 via the on-off valve 17 and the slow return valve 18 to exert a vibration suppressing effect.When the on-off valve 17 is switched, the oil chamber 8α and the accumulator 19 Since the pressures are approximately the same, the working device 7 will not be temporarily lowered.

Note that when the make contact 2 becomes closed and power begins to be supplied to the electric wire 29, the make contact 2 is given a holding function, regardless of whether the limit switch 5 is opened or closed, so unless the switch 6 is opened, If the circuit remains closed and power is supplied to the electric wire 29, the break contact 3 will open and the on-off valve 34 will no longer be energized.
is switched to the original C position to close the pipe line 30, and the pressure oil discharged from the hydraulic pump 11 flows only into the hydraulic switching valve 12.13. Furthermore, when the on-off valve 34 returns to the C position, pressure oil no longer flows into the flow rate detection valve 4, so that the pressure oil in the left oil chamber of the flow rate detection valve 4 flows through the throttle d built into the piston α. As the oil flows out into the tank 10 through the side oil chamber, the piston α gradually returns to neutral, and accordingly, the limit switch 5 also returns and the electric wire 33 becomes open.

Next, FIG. 2 shows a vibration suppressing bag ZF20 according to the present invention.
FIG. 3 is a diagram of the main electrical and hydraulic system of another embodiment for supplying pressure oil to the vehicle. In this figure, the branch pipe 30 in FIG.
Instead of providing the above on-off valve 34, the pressure oil discharged from the hydraulic pump 11 is normally supplied to the hydraulic switching valve 12 in the middle of the pipeline between the hydraulic pump 11 and the hydraulic switching valve 12. ,
A second on-off valve 38 is provided, which switches from the G position to the H position when a signal acts on the receiving part, and allows the pressure oil discharged from the hydraulic pump 11 to flow into the pipe line 30.
The electric wire 32 from the relay circuit 1 shown in FIG. 1 is connected, and the rest is completely the same as that shown in FIG. 1.

In the case of the circuit shown in FIG. 2 above, when the switch 6 is closed in order to apply the running vibration suppression function when a heavy load is applied to the working device 7, the on-off valve 38 is switched from the G position to the H position. The pressure oil discharged from the hydraulic pump 11 first flows into the switching valve 35 via the H position passage of the on-off valve 38 and the pipe line 30, and as described above, supplies the pressure oil to the vibration suppression device 20, and then the accumulator. When the accumulated pressure of the hydraulic pump 19 becomes approximately equal to the pressure of the head side oil chamber 8α, the power to the electric wire 32 is cut off, the on-off valve 38 returns to the G position, and the discharge pressure oil of the hydraulic pump 11 is completely discharged from the working device 7. It flows into the hydraulic switching valve that operates etc. At the same time, the on-off valve 17 shown in FIG. 1 is opened, and the conduit 16 is communicated with the vibration suppressor 20 to realize smooth switching. Therefore, in order to obtain the travel vibration suppressing effect, there is no need to specially manipulate the hydraulic switching valve for operating the working device 7, etc., and a stable circuit at the time of switching can be obtained.

FIG. 3 is an electrical/hydraulic system diagram of the main parts of the traveling vibration suppression and stabilization circuit provided at the portion where the pipe line 16 and the vibration suppression device 20 are connected via the on-off valve 17. In this figure, branch pipe 16. The vibration suppression device 20, the on-off valve 17, the electric wire 29 connected to the receiving part of the on-off valve 17, etc. are all the same as those in the embodiment shown in FIG. 16 and 16' are provided with a bypass pipe 40, and a check valve 39 of the circulation section only in the direction of the pipe 16 is provided in the middle of the bypass pipe.

In the circuit configuration shown in this figure, the pressure oil accumulated in the accumulator 19 is controlled regardless of the switching position of the on-off valve 17.
In addition, in response to load fluctuations on the lift cylinder 8, the pressure does not always become higher than the pressure in the head side oil chamber 8α.
On the other hand, the vibration suppressing effect is exerted only when the on-off valve 17 is in the B position. Therefore, if the working device 7 is discharged with a full load of sand and sand, and the pressure in the head side oil chamber 8α decreases, even if the on-off valve 17 is in the A position, excess pressure oil in the accumulator 19 will be released. flows out into the pipe 16 through the bypass pipe 40 and the check valve 39, and even if the discharge of the earth and sand is completed and the on-off valve 17 is immediately switched to the B position,
Since the pressures in the accumulator 19 and the head side oil chamber are approximately the same, the operating device 7 can automatically obtain a running vibration suppressing stability circuit that does not increase rapidly.

The circuits shown in FIGS. 1, 2, and 3 of the above embodiments can be used as a running vibration suppressing and stabilizing circuit in the running vibration suppressing device. By using a combination of FIG. 3 and FIG. 3, and FIG. 2 and FIG. 3, a more effective running vibration suppression stability circuit for a wheeled construction machine can be obtained.

Effects of the Invention If the stability circuit according to the present invention is added to the running vibration suppression circuit of the hydraulic means provided in a wheeled construction machine, the hydraulic circuit in normal working conditions can be changed to a circuit that exerts a vibration suppression effect. When switching is about to occur, the hydraulic pressure in the oil chamber of the hydraulic cylinder for supporting the working equipment and the hydraulic pressure accumulated in the accumulator in the vibration suppression circuit automatically become approximately the same. The accumulator does not swing up and down, and the accumulated pressure in the accumulator automatically corresponds to the weight of the work equipment including the workpiece.
No special operations are required, allowing safe and stable work.

[Brief explanation of the drawing]

Figures 1, 2, and 3 are electrical and hydraulic system diagrams showing embodiments of the present invention. Figure 1 shows the first embodiment, and Figure 2 shows the main parts of the second embodiment. FIG. 3 shows the main parts of the third embodiment, FIG. 4 is an external side view of the wheeled tractor shovel, and 5UA shows the main parts of the conventional running vibration suppression device installed in the wheeled tractor shovel. It is a hydraulic system diagram. 1 ・・・・・・・・・ Relay circuit 2 ・・・・・・・・・ Make contact 3 ・・・・・・・・・ Break contact 4 ・・・・・・・・・ Flow rate detection valve 5 ・・・・・・・
... Limit switch 6 ...... Switch 17.34.38 ...... Open/close valve 20
...... Vibration suppression device 35 ...... Switching valve and above

Claims (3)

[Claims] (1) A wheeled construction machine in which the base end of a working equipment boom is pivotally supported on the wheel body and supported by a hydraulic cylinder, in which a pipe line leading to the load-side oil chamber of the hydraulic cylinder is branched and connected to the receiving part. In a hydraulic operating circuit connected to a hydraulic vibration suppressing device during traveling via a first on-off valve that opens an internal oil path when a signal is applied, a discharge pipe of a hydraulic pump for working equipment and the first on-off valve A branch pipe line leading from the valve to the middle of the pipe line to the vibration suppressing device is provided, and a second on-off valve that opens the internal oil passage only when a signal acts on the receiving part is provided in the middle of the branch pipe line. , normally leads the branch pipe from the second on-off valve to the flow rate detection valve, and when a pressure higher than the pressure in the pipe leading to the vibration suppressor acts on the receiving part, the branch pipe connected in front and back The switching valve communicating with the passage is arranged in series, and
Power is supplied to the receiving part of the second on-off valve via a switch near the driver's seat, a limit switch operated by the flow rate detection valve, and a make contact with a holding function, and the receiving part of the second on-off valve is , power is supplied through a switch near the driver's seat and a break contact that opens when the receiving section of the first on-off valve is energized, and the receiving section of the switching valve is provided with a hydraulic cylinder that supports the working device. A running vibration suppression stability circuit for wheeled construction machinery in which a pilot pipe guides the pipe leading to the load-side oil chamber of the machine. (2) In the middle of the pipeline on the discharge side of the hydraulic pump for working equipment,
a second on-off valve that normally opens the conduit and, when a signal acts on the receiving section, opens the conduit to a branch conduit connected to the conduit between the first on-off valve and the vibration suppression device; and the second
In the middle of the branch pipe from the on-off valve, the branch pipe is normally led to a flow rate detection valve, and when a pressure higher than the pressure in the pipe leading to the vibration suppressor acts on the receiving part, the connection is made in front and back. A running vibration suppression and stabilization circuit for a wheeled construction machine according to claim 1, further comprising a switching valve that communicates with the branch pipe. (3) A bypass pipe is provided that communicates the branch pipe before and after the first on-off valve provided in the middle of the branch pipe leading from the load-side oil chamber of the hydraulic cylinder to the vibration suppression device, and the bypass Claims (1) and (2) further comprising providing a check valve in the middle of the pipeline that allows flow only in the direction of the pipeline leading to the load-side oil chamber of the hydraulic cylinder.
A running vibration suppression stability circuit for a wheeled construction machine as described in .