JPH0253623A - Travel vibration restraining and stabilizing circuit for wheeled contruction machine - Google Patents

Abstract

PURPOSE:To prevent unnecessary up and down swing motion of an operating equipment and improve the security by incorporating a safety circuit which has a make contact point, a break contact point and a plurality of change-over valves, in the travel vibration restraint circuit of a hydraulic means in a wheeled construction machine. CONSTITUTION:When a switch 6 is turned on, for example, electric current flows through a break contact point 3 and an electric wire 38 and to a secondary change-over valve 31. The secondary change-over valve 31 is then changed over to the position F so that a pipe passage 37 communicated with a tank 10 is communicated with a pipe passage 36. Discharge oil in a hydraulic pump 11 is flown via a pipe passage 33 and then into an accumulator 19 and when the pressure in a pipe passage 41 is increased higher than that in the pipe passage 37, a primary change-over valve 30 is changed-over to the position D. Then the discharge oil flows flows into a plurality of hydraulic change-over valves 12 and 13 via the pipe passage 32. And furthermore, when the electric current passing across and switch 6 runs via a limit switch 5 to excite a make contact point 2, an opening and closing valve 17 is changed-over to the position B to realize the vibro-isolation effect.

Description

[Detailed Description of the Invention] Industrial JLL Field This invention provides a system in which the 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 is also equipped with a hydraulic vibration suppression device. The present invention relates to a circuit that can automatically prevent a working device from descending under its own weight when switching between activation and deactivation of a running vibration prevention device in a non-shocked, wheeled 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 an on-off valve, and vibration is generated. The vibration suppression device was operated so as to be interposed in the load-side conduit of the hydraulic cylinder only while the vehicle was running.

For example, as a representative example of a wheeled construction machine, a wheeled tractor-shovel shown in FIG. 2 is equipped with an embodiment of a driving vibration suppressing device as shown in FIG. 3. Therefore,
When the 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-buffered and is supported entirely by rubber tires. Therefore, vibration is likely to occur.

In order to absorb the vibration energy at this time and dampen the vibration, the load side pipe line 15a of the lift cylinder 8 that supports the working device 7 is connected to the slow return valve 18 consisting of a throttle valve 18a and a check valve 18b, and an accumulator 19. By communicating with the vibration suppressing device 20 configured through the branch pipe 16, the working device 7 is vibrated separately from the vehicle body, leading to damped vibration.

On the other hand, the wheeled tractor Shirapel not only travels, but also lowers the bucket of the working device 7 to the ground, uses the forward force of the machine to dig the cutting edge into the earth and sand, and loads the Pakeso I with earth and sand to the dump cylinder 9. and lift cylinder 8
In many cases, the entire working device 7 is lifted up, 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 work is extremely low or at a standstill, and vibrations do not occur;
Accurate and safe work cannot be performed unless the bucket is held integrally with the vehicle body, so in such cases,
The lift cylinder 8 must be isolated from the vibration suppressor 20, but on the other hand, it is desirable that the lift cylinder 8 be in communication with the vibration suppressor 20 when the vehicle is running.

Therefore, an on-off valve [7] is interposed in the middle of a branch pipe 16 that communicates a pipe 15a leading to the head side oil chamber 8a, which is the load side of the lift cylinder 8, and the vibration suppressor 20, and is installed near the driver's seat. Switch 6 was being operated selectively.

Problems to be Solved by the Invention During a series of operations such as digging, moving, loading, and moving during work, it 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 work device 7, switch 6
Since the circuit is opened and the on-off valve 17 is in position A in FIG. 3, the pipe line 15a and the vibration suppressing device 20 are cut off.

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 8a of the lift cylinder 8 becomes high in proportion to the load on the bucket.Then, all earth and sand excavation operations are completed. When the switch 6 is closed to connect the vibration suppression device 20 and the conduit 15a to start traveling, the pressure is accumulated in the accumulator 19 up to the pressure of the conduit 15a. Therefore, a part of the pressure oil in the head-side oil chamber 8a of the lift cylinder 8 passes through the pipe 15a, the branch pipe 16, the B position passage of the on-off valve 17, and the slow return valve 18 to the accumulator 1.
9, the working device 7 is lowered relative to the vehicle body. In addition, when dumping earth and sand at a predetermined location after the next move, in order to prevent the vehicle from shaking, the switch and chiro are opened again to cut off communication between the conduit 15a and the vibration suppression device 20. The dump cylinder 9 is operated to discharge the earth and sand from the bucket. As a result, the load on the working device 7 is reduced,
The pressure in the pipe line 15a decreases accordingly. The vehicle begins to move from this state, but in order to suppress vehicle vibration while driving, switch 6 is closed and lift cylinder 8 is closed.
When the vibration suppression circuit 20 is communicated with the
9 is a head side oil chamber 8a corresponding to the load when fully loaded with earth and sand.
Since the high pressure of B remains unchanged, the on-off valve 17 is
A part of the pressure oil that had been accumulated at the moment of switching to the position flows into the head side oil chamber 8a of the lift cylinder 8, and the working device 7
This results in the vehicle 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 packet position required during work. This impedes speedy and safe work.

In view of this problem, the present invention has been developed so that when switching to the vibration suppression circuit state, the pressure in the head side oil chamber of the lift cylinder and the accumulated pressure in the accumulator are always maintained at the same level, so that the working device is useless against the vehicle body. The aim is to provide a stabilizing circuit that prevents vertical fluctuations at low cost.

Means for Solving the Problems In order to solve the above problems, the present invention takes the following measures. In other words, in the middle of the pipe connecting the vibration suppression device and the load-side oil chamber of the lift cylinder for the work equipment, there is an on-off valve that opens in response to an external electric signal, a port, a hydraulic pump, and a valve for the work equipment. It is located in the middle of the pipeline that connects the hydraulic switching valve, and is switched by a signal to supply the pressure oil discharged from the hydraulic pump to the hydraulic switching valve for working equipment, directly to the vibration suppression device, or to the accumulator in the equipment. A first switching valve that supplies oil until a predetermined pressure is accumulated; and (3) A receiving part of one of the first switching valves connects the load side oil of the lift cylinder to the tank by an electric signal from the outside. a second switching valve that causes a connection failure to the pipe line leading to the chamber; and two, a limit switch that operates when the pressure of the pipe line leading to the vibration suppression device becomes approximately equal to or higher than the load side pressure of the lift cylinder. E. The receiving part of the on-off valve has a make contact which is closed by the operation of a limit switch operated by the switch and the switch cylinder, and which has a function of maintaining the closed circuit state. A power source is connected to the receiving portion of the second switching valve through the switch and a break contact which opens at the same time as the make contact is activated.

Operation When the work equipment is raised by the lift cylinder and starts traveling, when the switch is closed, the power source acts on the receiving part of the second switching valve through the switch and the break contact, and the valve is switched. A pipe line leading to one receiving portion of the switching valve is connected to a pipe line leading to the load side oil chamber of the lift cylinder. At this time, when the pressure in the load-side oil chamber of the lift cylinder is higher than the pressure in the pipeline leading from the first switching valve to the vibration suppression device, the first switching valve allows the discharge pressure oil of the hydraulic pump to reach the vibration suppression device. Since the pressure is switched to the side where the supply is supplied to the side, pressure is accumulated in the achi emulator of the vibration suppression device, and when the pressure on the other side becomes almost equal to the load side pressure of the lift cylinder, the limit switch is activated by the action of the switch cylinder, and the make contact is closed. The circuit is closed and maintained in the closed state, so power is continuously supplied to the receiving part of the on-off valve, and the load-side oil chamber of the lift cylinder and the vibration suppression device are connected to the pipe line and the on-off valve. communicate via. At this time, since the pressure in the load-side oil chamber of the lift cylinder and the pressure in the vibration suppressor are approximately equal, the working device maintains its position even if the on-off valve is opened.

In addition, as soon as the make contact is activated, the break contact is opened and the operation of the second switching valve is stopped, so the pipe line leading to one receiving part of the switching valve is connected to the tank, so the valve is switched, The pressure oil discharged from the hydraulic pump flows into the hydraulic switching valve for the working equipment.

In this way, it is possible to obtain the effect of suppressing the vibration of the vehicle body while driving, and it is also possible to operate the working equipment, but it also prevents the working equipment from inadvertently descending even when the on-off valve is activated. do not have.

Next, when performing operations such as excavating, scooping, and discharging, it is more reliable and safe to operate without the vibration suppressor, but in this case, by leaving the switch open, the lift cylinder Since the load-side oil chamber and the vibration suppression device are isolated by an on-off valve, powerful and reliable operation of the work equipment is achieved.

At this time, since the second switching valve connects the pipe line leading to one of the receiving parts of the first switching valve to the tank, the entire amount of pressure oil discharged from the hydraulic pump is transferred through the first switching valve. Direction flows into the hydraulic switching valve for the working equipment.

Example Embodiments of this 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, 10 is a tank, 11 is a hydraulic pump for operating the working equipment in the hydraulic power unit, and 12 is a hydraulic switching valve for the dump cylinder 9. A head-side oil chamber 9a and a rod-side oil chamber 9b of the dump cylinder 9 are connected to the hydraulic cut-off valve 12 via pipes 14a and 14b, and 13 is a hydraulic switching valve for the lift cylinder 8; 13
A head side oil chamber 8a and a rod side oil chamber 8b of the lift cylinder 8 are connected to each other via pipes 15a and 15b. 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 head side oil chamber 8a.
A branch pipe line 16 is provided in the middle of the pipe 5a, and this branch pipe line 16 is connected to a throttle valve 18a and a check valve 18b via an on-off valve 17.
The slow return valve 18 is further connected to an accumulator 19. The above-mentioned on-off valve 17 normally closes the branch pipe 16 by the biasing force of a built-in spring, and when an electric signal is input to its receiving section, it opens and closes the branch pipe 16 as a slow return valve. 18 and a vibration suppressor 20 consisting of an Akiemulator 19. Further, as the accumulator 19, a plug type accumulator is usually used, and depending on the load size, working conditions, installation space, etc., one or more may be used, or the on-off valve 17,
Vibration suppression value! It may be used in various combinations such as singular or plural including 20.

In addition, 21 is a main relief valve, 22, 23, and 24 are overload relief valves of the circuits communicating with the pipes 14a, 14b, and 15a, respectively, 25.26.27
．． 28 is a check valve for preventing cavitation.

In addition, 1 in the figure is a relay circuit that has a make contact 2, a break contact 3, a switch 6 for opening and closing the power supply, etc. The make contact 2 is normally open, but when the switch 6 is closed, the limit is reached. Once the electric wire 39 is closed by the switch 5, power is continuously supplied to the electric wire 40 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. However, it is an electrical circuit of known technology that is designed to be open while the electric wire 40 is energized regardless of whether the limit switch 5 is opened or closed, and 4 is a rod containing a head side oil chamber 4a and a spring. A switch cylinder equipped with a side oil chamber 4b,
Although it is normally contracted by the biasing force of the spring, the oil chamber 4a
As the pressure increases, and when it becomes approximately equal to the pressure in the oil chamber 4b, it expands, and the tip of the iron reaches the limit switch 5.
The above-mentioned on-off valve 17 and the vibration suppressor 1E2 are arranged in the head side oil chamber 4a to close the internal electric circuit of the limit switch 5.
The pipe line 33 branched from the pipe line connecting to the pipe line 34
A conduit 35, which is an extension of the conduit 15a, leads to the rod-side oil chamber 4b.

Furthermore, the pressure oil of the hydraulic pump 11 is
In the middle of the pipe line 32 flowing into the hydraulic switching valve group consisting of
A first switching valve 30 is provided which switches to the C position by the signal pressure generated in the conduit 37 or to the D position by the signal pressure generated in the conduit 41, and when the first switching valve 30 is in the C position The pressure oil discharged from the hydraulic pump 11 is directed to the pipe line 33 via the check valve 29, and when the position is switched to the D position, the passage to the pipe line 33 is blocked and the oil is guided to the pipe line 32. , the valve remains in the C position when the pressures in lines 37, 41 are approximately equal.

Reference numeral 31 designates a second electromagnetic switching valve, and an electric wire 38 leading to the power supply via the break contact 3 is led to the receiving part of the valve.
7 is connected to the tank 10, but when it is energized, it is switched to the F position, and the pipe 37 is branched from the pipe 35.
6.

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

When stopping the wheeled tractor excavator, or when operating the excavation and scooping of earth and sand, raising and lowering the working equipment while running at extremely low speed, operate the hydraulic selector valves 12 and 13 with the switch 6 open. At this time, neither the on-off valve 17 nor the second switching valve 31 is energized, so the on-off valve 17 is in the A position, and the branch pipe 16 and the vibration suppressor 20 are connected to each other. The second switching valve 31 is in the E position and allows the pipe line 37 to communicate with the tank 10. On the other hand, the hydraulic pump 11 is already in operation, and its discharge pressure oil is sent to the C position passage of the first switching valve 30 and the check valve 29.
, the pipe 33 and the slow return valve 18 to flow into the accumulator 19, but since it has a finite volume, it immediately fills up, and the pressure in the pipe 33 rises, and at the same time the pressure in the pipe 41 also becomes higher than that in the pipe 37. is also high (as a result, the first switching valve 3
0 is switched to the D position against the urging force of the spring,
While maintaining that position, the discharge pressure oil of the hydraulic pump 11 is passed through the D position passage of the first switching valve 30 and the pipe 32 to the hydraulic switching valve 12.
．． 13, and by operating the switching valve, the lift cylinder 8 and dump cylinder 9 are expanded and contracted. Therefore, under this condition, the working device 7 is reliably supported with respect to the vehicle body by the lift cylinder 8, and performs accurate operation in accordance with the operation of the hydraulic switching valves 12, 13, like a normal machine.

After completing the scooping of earth and sand into the packet, when starting to travel on the undulating transport road, first close the sui-nochi 6 and then operate the hydraulic switching valves 12 and 13 to adjust the travel attitude.

During this time, the power supply is switched to switch 6, break contact 3,
It passes through the electric wire 38 and acts on the receiving part of the second switching valve 31, so that the cough valve is switched from the E position to the F position, causing the pipe 37 that was previously connected to the tank 10 to be connected to the pipe 36, and Therefore, the first switching valve 30 maintains the C position when the pressure in the pipe 37, that is, the pipe 16a is higher than the pressure in the pipe 41, that is, the accumulator 19, but the pressure oil discharged from the hydraulic pump 11 is 33, it flows into the accumulator 19 and the pressure is accumulated, and as the pressure in the pipe line 41 becomes higher than that in the pipe line 37, the pressure oil is switched to the D position, and the pressure oil discharged from the hydraulic pump 11 passes through the pipe line 32, and the pressure oil is switched to the D position. Flow into valve 12.13.

On the other hand, the pressure of the pipe line 34 leading to the head side oil chamber 4a of the switch cylinder 4 is equal to the pressure of the accumulator 19,
A pipe line 35 leading to the rond side oil chamber 4b is connected to the lift cylinder 8.
The head side oil chamber 4 is equal to the pressure of the head side oil chamber 8a, which is the load side of
When the pressure in a gradually increases and becomes almost equal to or higher than the pressure in the rond side oil chamber 4b, the switch cylinder 4 expands against the biasing force of the built-in spring, and the rond tip touches the limit switch 5. Since it acts on the actuator to close the internal electric circuit of the limit switch 5, the electric wire 39 becomes short-circuited. Along with this, switch 6
The power passing through excites the make contact 2 via the limit switch 5, so the make contact 2 is closed, and the power is connected to the receiving part of the on-off valve 17 via the electric wire 40 connected thereto. The on-off valve 17 switches from the A position to the B position, and 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 changing, as described above, the pressures in the oil chamber 8a and the accumulator 19 are approximately the same, so the working device 7 does not temporarily lower.

Note that once the make contact 2 is in a closed state and power begins to be supplied to the electric wire 40, 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, When the closed circuit state continues and power is supplied to the electric wire 40, the break contact 3 opens and the second switching valve 31 is no longer energized, so the valve switches to the original E position, so the first switching valve 30 maintains the D position as long as there is load pressure in the pipe line 33, and does not interfere with the operation of the working device.

To summarize the above operation, when this machine is operated with the switch 6 open, the running vibration suppression device does not operate and the conventional standard performance is exhibited. Also, switch 6
When the circuit is closed, if the internal pressure of the accumulator of the vibration suppression device is lower than the load side pressure of the lift cylinder, the discharge pressure oil of the hydraulic pump automatically closes the
After accumulating pressure in the accumulator and making the pressures on both sides approximately the same, the load side oil chamber of the lift cylinder and the vibration suppression device are connected.

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, it will be possible to switch from the hydraulic circuit in normal working conditions to a circuit that exerts a vibration suppression effect. When switching, 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, so that the working equipment does not move up or down at the time of switching. In addition, the accumulator's accumulated pressure automatically corresponds to the weight of the work equipment including the object to be worked on.
No special operations are required, allowing safe and stable work.

[Brief explanation of the drawing]

Fig. 1 is an electrical/hydraulic system diagram showing an embodiment of the present invention, Fig. 2 is an external side view of a wheeled tractor excavator, and Fig. 3 is a main part of a conventional running vibration suppression device installed in a wheeled tractor excavator. This is an electrical/hydraulic system diagram. 1... Relay circuit 2... Make contact 3... Break contact 4... Switch cylinder 5...・
... Limit switch 17 ...... Opening/closing valve 20 ...... Vibration suppressor 30 ...... First switching valve 31 ...... First 2 switching valves or more

Claims (1)

[Claims] In a wheel-type construction machine in which a base end of a working equipment support member is pivotally supported on a vehicle body and supported by a lift cylinder, a signal is input to a receiving unit through a conduit leading to a load-side oil chamber of the lift cylinder. In a hydraulic running vibration suppression circuit connected to a vibration suppression device via an on-off valve that opens when The first switching valve supplies oil to the hydraulic switching valve for operating the actuator, or directly to the vibration suppression device until a predetermined pressure is accumulated in the accumulator in the device, and an electric signal from the outside. The first switching valve issues a signal to switch to the side that supplies pressure oil to the vibration suppression device, and the pressure in the pipe line leading to the vibration suppression device is approximately equal to or higher than the load pressure of the lift cylinder. When the limit switch is activated, the receiving part of the on-off valve is connected to a power source via a make contact which closes when the switch and the limit switch are activated and has a holding function.
A running vibration suppressing and stabilizing circuit for a wheeled construction machine, characterized in that a power source is connected to a receiving part of the switching valve via the switch and a break contact that opens at the same time as the make contact is activated.