JP2688966B2 - Running vibration suppression and stabilization circuit for wheeled construction machines - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a base end of a working device protruding from a vehicle main body pivotally supported on the vehicle main body so as to be vertically rotatable, and a hydraulic vibration suppression device is also provided. Operation of traveling vibration prevention device in non-buffered, wheel-type construction machinery supported by hydraulic cylinders
The present invention relates to a hydraulic circuit that automatically excludes the work device from descending by its own weight when switching the inaction, and also protects the equipment.

2. Description of the Related Art Conventionally, a vibration suppression device is provided in a load side circuit of a hydraulic cylinder that supports a working device protruding from a vehicle body of a wheel type construction machine, and the vibration suppression device is provided to be freely opened and closed by an on-off valve.
The vibration suppression device is operated so as to be interposed in the load-side pipeline of the hydraulic cylinder only during traveling where vibration occurs.

For example, FIG. 5 shows a general electric / hydraulic system of a main part of a traveling vibration suppressing device provided in a wheel type tractor shovel as shown in FIG. 4 as a representative example of a wheel type construction machine. In this way, the working device 7 of the wheel type tractor excavator projects forward from the front axle, and its weight ratio is large, the axle is non-buffering type, and the whole is supported by rubber tires. Vibration of the machine is likely to occur.

At this time, for the purpose of absorbing the vibration energy to generate a damping vibration and quickly stabilizing the machine body, the load side pipe 15a of the lift cylinder 8 supporting the working device 7 is checked by the branch pipe 16 to check the throttle valve 18a. Vibration suppressor consisting of slow return valve 18 consisting of valve 18b and accumulator 19
By communicating with 20, the working device 7 is vibrated separately from the vehicle main body, and leads to damped vibration.

On the other hand, the wheel-type tractor shovel not only travels, but also lowers the bucket of the working device 7 to the ground, makes the cutting edge penetrate the earth and sand by the forward force of the fuselage, loads the bucket with the earth and sand, and raises the bucket by the dump cylinder 9. , Lift cylinder 8
In many cases, the entire work apparatus 7 is lifted, adjusted to an appropriate height at another point, and the dump cylinder 9 is operated again to dump the soil. When loading in such excavation and loading work, etc., the traveling speed at the time of dumping is extremely low or stopped, and vibration does not occur, rather,
If the bucket is not held integrally with the vehicle body, accurate and safe work cannot be performed.
The lift cylinder 8 must be cut off from the vibration suppressing device 20. On the other hand, it is preferable that the lift cylinder 8 communicates with the vehicle when traveling. Therefore, the pipeline 15a leading to the head-side oil chamber 8a on the load side of the lift cylinder 8 and the vibration suppressing device 20
A switching valve 17 is interposed in the middle of a branch pipe line 16 communicating with
The switch 6 provided near the driver's seat was selectively operated.

Problems to be Solved by the Invention During a series of operations such as excavation / movement / loading / movement at the time of work, the number of times must be at least twice, or further depending on the traveling distance, traveling road surface, and the situation of obstacles. Again, the opening and closing operation of the communication between the lift cylinder and the vibration suppression device becomes frequent. To describe this situation specifically,
Since the switch 6 is opened and the opening / closing valve 17 is set to the position A in FIG. 5 when loading the soil of the bucket of the working device 7, the pipeline 15a and the vibration suppressing device 20 are cut off. In this state, when earth and sand are loaded into the bucket and the working device 7 is raised, the circuit pressure of the head-side oil chamber 8a of the lift cylinder 8 becomes
The pressure increases in proportion to the bucket load. Next, when completing the excavation operation of the earth and sand and starting traveling for movement, the switch 6 is closed to connect the vibration suppressing circuit 20 and the pipe 15a to each other to suppress vibration during traveling, and the accumulator 19 is connected. Since the pressure is not accumulated up to the pressure of the pipe line 15a in the pipe line 15, a part of the pressure oil in the head side oil chamber 8a of the lift cylinder 8 is not stored in the pipe line 15a.
a, the work apparatus 7 descends with respect to the vehicle body because it flows into the accumulator 19 through the branch conduit 16, the B-position passage of the on-off valve 17, and the slow return valve 18. Further, when the soil is dumped at a predetermined place after the next movement, the switch 6 is opened again to prevent the vehicle from shaking, and the pipeline 15a is opened.
Communication with the vibration suppression device 20 is cut off, and the dump cylinder 9
To release the soil in the bucket.

During the series of operations as described above, it is often very dangerous that the working device is slightly lowered at the moment when the switch 6 for operating the vibration suppressing device 20 is closed because the bucket is scooped with sand and moved. Therefore, as shown in FIG. 6, the pressure of the relay circuit 44 between the receiving portion of the opening / closing valve 17 and the switch 6 and the pressure of the pipe line 33 communicating with the vibration suppressing device 20 are transferred to the head side oil chamber 8a of the lift cylinder 8. A differential pressure switch 45 that closes only when it is approximately equal to or higher than that of the communicating pipe 15a, and when the pressure in the conduit 33 is lower than that in the conduit 15a, the pressure is generally maintained until the pressure reaches that level. ,Hydraulic pump
The first switching valve 30 that preferentially supplies the discharge pressure oil of 11 to the pipeline 33
And a second switching valve 31 that operates the first switching valve in response to a command from the relay circuit 44, and even if the switch 6 is closed, the pressure accumulated in the vibration suppressing device 20 is In general, an electric / hydraulic circuit is provided so that the opening / closing valve 17 does not open unless it becomes the same as that of the conduit 15a, that is, the conduit 16.

However, the lift cylinder 8 generates pressure in the head-side oil chamber 8a in response to static and dynamic loads on the entire working device 7, and varies greatly during normal excavation, transportation, and other operations. , A hydraulic circuit corresponding to these high pressures is built. For example, when excavation work is performed with the dump cylinder 9, a pressure much higher than the static weight load pressure of the work device 7 including the work object is generated in the oil chamber 8a due to the reaction force of the excavation resistance. When excavating or running with the switch 6 closed, the accumulator 19 in the vibration suppressing device 20 as described above accumulates a pressure corresponding to the maximum pressure generated in the oil chamber 8a, and thus the life of the accumulator. Becomes shorter.

In view of this point, when the present invention is operated to the traveling vibration suppression stabilization circuit operating state, pressure oil flows into the accumulator of the vibration suppression device, and its pressure becomes substantially equal to the pressure of the head side oil chamber of the lift cylinder. Therefore, it is the same as the conventional method to open the on-off valve that communicates the oil chamber with the vibration suppression device, but during excavation work, as described above, the pressure in the oil chamber on the head side of the lift cylinder increases to suppress vibration. When the pressure in the circuit exceeds a certain pressure, the on-off valve is automatically closed, and the pressure oil supply to the vibration suppression circuit is stopped to protect the accumulator and improve the efficiency of excavation work. It is an object of the present invention to make an improvement and automatically obtain a traveling vibration suppressing and stabilizing circuit during normal traveling after completion of excavation work.

Means for Solving the Problems In order to solve the above problems, the present invention employs the following means. That is, a. ) An on-off valve in the middle of the communication line between the vibration suppression device and the load-side oil chamber of the lift cylinder, in which the internal oil passage is opened by a signal from the outside, and b. ) The discharge pressure oil of the hydraulic pump is supplied to the vibration suppression device only when a pressure higher than the accumulated pressure of the accumulator in the vibration suppression device acts on the receiving part in the middle of the discharge side pipeline of the hydraulic pump. A first switching valve that is switched as necessary, and c. ) A second switching valve that switches a receiving portion of the first switching valve communicating with the tank so as to communicate with the load side oil chamber of the lift cylinder by a signal from the outside, and d. ) Pressure detector, pressure switch, break contact,
Control means comprising a make contact or the like and having a function of transmitting a signal to the receiving portions of the first switching valve and the second switching valve; ) A switch for a signal for instructing the execution and stop of the operation of the above-mentioned control means, which is easily operated from the driver's seat, is provided. ) The signal emitted by the control means supplies the signal to the receiving portion of the second switching valve under the command of the operation execution by the means, but the pressure in the vibration suppression device introduced to the pressure detection device is lifted. When the pressure on the load side of the cylinder is approximately equal to or higher than that, the signal to the receiving portion of the second switching valve is stopped,
At the same time, a signal is supplied to the receiving portion of the on-off valve, and when the pressure inside the vibration suppression device exceeds a predetermined pressure, a function of stopping all signals to the receiving portion of the on-off valve and the second switching valve is given. .

While the switch for the action signal is closed and the control means is in the operation execution state, while the accumulated pressure of the accumulator of the vibration suppression device introduced to the pressure detection device is lower than the standard load pressure of the lift cylinder. The signal from the control means is supplied only to the second switching valve. Therefore, the on-off valve maintains the closed state, the pressure of the load-side oil chamber of the lift cylinder acts on the first switching valve by the operation of the second switching valve, and the discharge pressure oil of the hydraulic pump operates the first switching valve. Pass into the accumulator.
Then, when the pressure of the accumulator and the pressure of the load side oil chamber of the lift cylinder become approximately the same pressure, the pressure detection device operates, and the control means causes the signal to the second switching valve by the action of the internal make contact and break contact. And a signal is supplied to the on-off valve. As a result, the pipeline that communicates with the load-side oil chamber of the lift cylinder communicates with the vibration suppression device that has an accumulator that is stored at approximately the same pressure as this pressure via the internal passage of the on-off valve, so the on-off valve opens. If the working device is raised to the required height by the lift cylinder and the vehicle travels without lowering the working device at the moment of doing so, the vibration suppressing effect of the vehicle body can be obtained.

Next, during operation of the control means, the pressure in the load-side oil chamber of the lift cylinder approaches the set maximum pressure due to, for example, excavation work by the work device or abnormal load on the work device from the outside. Sometimes. On the other hand, it is not only expensive to make the maximum allowable pressure of the accumulator of the vibration suppressing device, which is communicated via the on-off valve, high pressure, but also a problem of its durability arises. In such a case, in the present invention, the pipe line leading to the vibration suppressing device leads to the pressure switch constituting the control means, and when a pressure above a predetermined level acts on the pressure switch, a signal is transmitted via the break contact. And the control means is an on-off valve, a second
No signal is supplied to any of the switching valves.

Therefore, for example, even when excavation work is performed with the signal switch closed, the accumulated pressure of the accumulator does not rise abnormally and the working device does not rotate with respect to the vehicle body. Excavation work is performed.

When the signal switch is opened to stop the operation of the control means, no signal is supplied from the means to the on-off valve and the second switching valve. Needless to say, is given.

Embodiment An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is an electric / hydraulic system diagram when a normal vibration suppressing device and a traveling vibration suppressing and stabilizing circuit according to the present invention are provided in a wheel type tractor shovel as a typical example of a wheel type construction machine.

In the figure, 8 and 9 are lift cylinders and dump cylinders for working devices, 10 is a tank, 11 is a hydraulic pump for operating working devices in a hydraulic power unit, and 12 is a hydraulic switching valve for dump cylinders 9. Line 14 to hydraulic switching valve 12
The head side oil chamber 9a and the rod side oil chamber 9b of the dump cylinder 9 are connected via a and 14b, 13 is a hydraulic pressure switching valve for the lift cylinder 8, and the hydraulic pressure switching valve 13 is provided with pipe lines 15a and 15b. The head side oil chamber 8a and the rod side oil chamber 8b of the lift cylinder 8
Is connected. Furthermore, in the lift cylinder 8,
Oil chamber on the load side by the working device, that is, head side oil chamber 8a
A branch pipe 16 is provided in the middle of the pipe 15a connected to the branch pipe 16. The branch pipe 16 is connected to a slow return valve 18 including a throttle valve 18a and a check valve 18b via an opening / closing valve 17 and The return valve 18 is further connected to an accumulator 19. The on-off valve 17 normally closes the branch pipe line 16 by the biasing force of the built-in spring, and opens when the electric signal is input to the receiving portion of the on-off valve 17, and opens the branch pipe line 16 through the slow return valve. Vibration suppressor 20 consisting of 18 and accumulator 19
It is designed to communicate with. Also accumulator
A prada type accumulator is usually used as 19 and may be one or more in view of the load, working conditions, installation space, etc., or various combinations such as the on-off valve 17 and the vibration suppression device 20 such as one or more. It may also be used.

Reference numeral 21 is a main relief valve, 22, 23 and 24 are overload relief valves of circuits communicating with the pipelines 14a, 14b and 15a, respectively, and 25, 26, 27 and 28 are check valves for preventing cavitation.

Furthermore, in the middle of the pipeline 32 in which the pressure oil of the hydraulic pump 11 flows into the hydraulic pressure switching valve group consisting of the hydraulic pressure switching valves 12 and 13, the pipeline 37 among the pipelines 37 and 41 leading to the receiving part is The C position when the pressure is high, and the D position when the line 41 is higher
When the switching valve 30 is provided and the first switching valve 30 is in the C position, the hydraulic fluid discharged from the hydraulic pump 11 is discharged from the check valve 29 and the pipeline.
When the vibration suppressing device 20 is switched to the D position through 33, the passage to the check valve 29 is shut off and guided to the pipe 32. Reference numeral 31 is an electromagnetic second switching valve, which is connected to the control means 1 described later by an electric wire 38 at the receiving portion, is in the E position by the biasing force of the spring, and connects the pipeline 37 to the tank 10. However, when a signal is supplied, it switches to the F position,
The conduit 37 is communicated with the conduit 36 branched from the conduit 15a. Further, 39 is an electric wire, which connects the above-mentioned control means 1 and the receiving part of the on-off valve 17, and 6 is a main switch for connecting and disconnecting the power supply to the control means 1.

Then, 1 is the above-mentioned control means,
For example, as shown in FIG. 1, the pressure detecting device 5 for interlocking the make contact 2, the pressure switch 4, the break contacts 3a, 3b,
It is composed of 3c etc. The pressure detecting device 5 has 2
The oil chambers are divided into two, and each oil chamber has a pipeline 34 branched from the pipeline 15a and a pipeline 3 branched from the pipeline 33.
When the pressure in the pipe line 35 becomes substantially equal to or higher than the pressure in the pipe line 34, the built-in make contact 2 which has been open until then is closed, and the pressure switch 4 is introduced. The pipeline 33 is branched to the pipeline 42, and the pipeline 42 is guided to the pipeline.
When the pressure of 42 exceeds a predetermined pressure or becomes abnormally high, the internal electric circuit of the pressure switch is closed.

Further, 3a, 3b, 3c are all break contacts, and the internal electric circuit is normally closed, but it is opened when excited. In addition, both 40 and 41 are electric wires and constitute an electric circuit in the control means 1.

Next, the operation of the invention configured as above will be described.

When the wheel-type tractor shovel illustrated is used without operating the normal traveling vibration suppressing circuit, the main switch 6 may be operated with the circuit open, so a detailed description of the operating state at that time will be omitted. Only the operation when running or excavating work with the main switch 6 closed will be described.

First, when traveling, when starting the operation of the traveling vibration suppressing device, the hydraulic pump 11 is driven by the engine (not shown), and the working device 7 is driven by the lift cylinder 8 against the dead weight or the load of the load. Assuming a held state, a certain pressure is generated in the load side oil chamber 8a and the pipe line 15a leading to this. Therefore, if the main switch 6 is closed while the accumulated pressure of the accumulator 19 of the vibration suppressing device 20 is significantly lower than the certain pressure in the pipe 15a, the pressure in the pipes 33, 35 will be the same. Since the pressure is lower than the pressures of 15a and 34, the make contact 2 in the pressure detection device 5 is open, so the power source leading to the main switch 6 and the electric wire 40 is not connected to the electric wire 39. Hold. On the other hand, the power source of the electric wire 40 passes through the break contacts 3a, 3b and the electric wire 38 which are arranged in series and closed, and the second switching valve 31 serves as a signal.
The second switching valve switches from the E position to the F position as a result of reaching the receiving section of the above, and as a result, the pipe lines 36 and 37 are communicated. At this time, since the pipeline 41 is connected to the pipeline 33 and the pipeline 36 is lower than the pressure in the pipeline 36, the first switching valve 30 is in the C position, and the hydraulic fluid discharged from the hydraulic pump 11 is in the C position passage of the first switching valve 30. Check valve 29, pipeline
It passes through the slow return valve 33 and the slow return valve 18 and flows into the accumulator 19 to increase the internal pressure of the vibration suppressing device 20.
Along with this, when the pressure in the pipe line 35 becomes substantially equal to or higher than the pressure in the pipe line 34, the pressure detection device 5 operates to close the built-in make contact 2. Then the electric wire 40
The power source of the above operates via the make contact 2 and the break contact 3c, and acts as a signal on the receiving portion of the on-off valve 17 via the electric wire 39 to switch the valve from the A position to the B position, and at the same time in the control means 1. Since the break contact 3a is opened, the signal to the electric wire 38 is stopped, and the second switching valve 31 moves from the F position to the E position.
Further, the first switching valve 30 switches from the C position to the D position, and the hydraulic fluid discharged from the hydraulic pump 11 flows into the hydraulic switching valve group consisting of the hydraulic switching valves 12 and 13 to prepare for the operation of the working device 7. Of course, it is possible to do so, but at the moment when the opening / closing valve 17 is switched to the B position, the front and rear pressures are almost equal, so the working device does not descend against the driver's will.

Further, when excavation work is performed with the main switch 6 closed, an excessive load is applied to the lift cylinder 8 by the excavation reaction force of the work device 7 or an unexpectedly large external force, and the pipes 15a, 33, 42 When the pressure becomes equal to or higher than a predetermined pressure, the pressure switch 4 is activated and the power source of the electric wire 40 passes through the electric wire 41 and opens the break contacts 3b and 3c, so that the control device 1 can operate regardless of the state of the make contact 2. From, the signals to the on-off valve 17 and the second switching valve 31 are all stopped, and the same as when the main switch 6 is opened, that is, when the vibration suppressing device does not operate. It is not necessary to open the switch 6 each time, and the accumulator is protected.

FIG. 2 is an electric / hydraulic system diagram showing a second embodiment of the present invention. The hydraulic pump 11 shown in the first embodiment is a hydraulic pump for operating a working device and a pressure oil filling device for a vibration suppressing device. I shared with you, but this is not always necessary,
This is an embodiment in which a hydraulic pump 43 is provided separately from the hydraulic pump 11 in order to make the operation smoother, and the operation and effect are the same as in the first embodiment.

FIG. 3 is an electric system diagram showing another embodiment 1a of the control means 1 in FIGS. 1 and 2. This system diagram and that of FIG. 1 are different in the arrangement and combination of the break contacts 46a, 46b and the make contacts 2, 47, and their operation is from the main switch 6 which is a switch for signals. The signal power is supplied to the pressure switch 4 and the break contact 46a through the wire 40, and in the state shown in the figure, the power is transmitted to the wire 38 as a signal through the break contact 46a and the break contact 46b. When the pressure in the pipe line 35 becomes equal to or higher than the pressure in the pipe line 34, the make contact point 2 of the pressure detection device 5 is closed, so that the make contact point 47 is closed.
A signal is transmitted to the electric wire 39, the break contact 46b is opened, and the signal to the electric wire 38 is cut off.

Further, as described in the operation in the above-mentioned embodiment, when the pressure in the pipe 42 rises above a predetermined value, the pressure switch 4 is closed, and as a result, the break contact 46a is opened, and the electric power to the parts other than the pressure switch 4 is opened. Since all the circuits are cut off, all signals to the electric wires 38 and 39 are interrupted, but when the pressure switch 4 is automatically restored, the control means 1a starts operating again.

As described above, the control means 1, 1a shown in FIGS. 1 and 3 show an example of a part in which the power source is used as a signal medium and the pressure detecting device, the pressure switch, and various contacts are combined. The control means in the invention is not limited to the device having the characteristics described here, and for example, the opening / closing valve 17, the second switching valve 31, and the pressure detection device 5, the pressure switch 4, and the break in the control means 1. Contacts 3a, 3b, 3c, 46a, 46b,
In the combination of make contacts 2, 47, etc., their characteristics are reverse characteristics, or even if they are replaced with electric fluid as a signal medium, or fluid such as hydraulic pressure or pneumatic pressure, they can be used in one direction. The switching to the traveling vibration suppressing circuit of the wheel type construction machine can be realized by an easy operation, and the accumulated pressure of the accumulator 19 is lower than the load side oil chamber pressure of the lift cylinder 8 while the traveling vibration suppressing circuit is operating. At this time, until the pressure becomes almost the same, the discharge pressure oil of the hydraulic pump 11 or 43 is controlled by the vibration suppressing device 20.
The automatic opening of the on-off valve 17 when the pressure becomes almost the same, and at the same time, stop the flow of pressure oil to the vibration suppression device by the hydraulic pump, and for some reason, suppress the vibration. When the pressure in the device becomes an abnormal pressure of a predetermined value or more, it is automatically detected that the pressure oil of the hydraulic pump 11 or 43 flows into the vibration suppressing device 20 side at the position where the on-off valve 17 is closed. Any control means may be used as long as it outputs a signal to bring the position of the second switching valve 31 to stop.

EFFECTS OF THE INVENTION If a stabilizing circuit according to the present invention is provided along with a traveling vibration suppressing circuit of hydraulic means provided in a wheel-type construction machine, the hydraulic circuit in a normal working state is switched to a circuit that can obtain a vibration suppressing effect. When the operation is performed, automatically, with priority, the hydraulic pump replenishes pressure oil to the accumulator in the vibration suppressor until the pressure in the load-side oil chamber of the work equipment supporting lift cylinder becomes approximately equal, and then the vibration Since the suppression device operates, safe operation and good riding comfort can be obtained without lowering the work device against the driver's will during switching, and excavation work etc. If the pressure in the load-side oil chamber of the work equipment supporting lift cylinder becomes an abnormal pressure above the predetermined pressure allowed by the accumulator, the load-side oil chamber and the vibration suppression device will automatically Since the pipe line between the hydraulic pump and the storage device is cut off, and at the same time, the supply of pressure oil from the hydraulic pump to the vibration suppression device is also stopped,
Since the accumulator is protected and the working device is integrated with the machine body through the lift cylinder, it is possible to improve the durability of the vibration suppressing device, simplify the driving operation, and contribute to safe driving.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention, FIG. 2 shows an electric / hydraulic system diagram showing the second embodiment, and FIG. 3 shows another embodiment of the control means in FIGS. 1 and 2. Electrical diagram, No. 4
FIG. 5 is an external side view of a wheel type tractor shovel, FIG. 5 is an electric / hydraulic system diagram of a main part showing a conventional general traveling vibration suppressing circuit provided in the wheel type tractor shovel, and FIG. It is an improved conventional electric and hydraulic system diagram. 1,1a ...... Control means 2 ...... Make contact 3a, 3b, 3c ...... Break contact 4 ...... Pressure switch 5 ...... Pressure detection device 17 ...... Open / close valve 20 ...... Vibration suppression device 30 ...... First switching valve 31 …… Second switching valve

Claims (1)

(57) [Claims] 1. A wheel-type construction machine in which a base end portion of a working device support member is pivotally supported on a vehicle body and is supported by a lift cylinder, and a pipe line communicating with a load side oil chamber of the lift cylinder is provided. In a hydraulic traveling vibration suppression circuit connected to a vibration suppression device via an opening / closing valve that opens due to the action of a signal, the vibration suppression device is provided in the middle of a conduit connecting an oil pressure source and the upstream conduit of the opening / closing valve. The first switching valve that guides the hydraulic pressure source to the upstream pipe only when a pressure higher than the pressure of the first switching valve acts on the receiving section, and the receiving section of the first switching valve that is opened when a signal acts on the receiving section. A second switching valve that connects a pipe communicating with the pipe to a pipe communicating with the load-side oil chamber of the lift cylinder;
When a signal is input from the driver's seat through a signal switch that can be opened and closed, a signal is output to the receiving portion of the second switching valve, and the pressure in the vibration suppression device causes the pressure in the load-side oil chamber of the lift cylinder to rise. When the pressure is approximately equal to or higher than the pressure, a signal is output to the receiving portion of the on-off valve and at the same time the signal output circuit to the receiving portion of the second switching valve is shut off. When the value exceeds the limit, a traveling vibration suppression stabilizing circuit for a wheel-type construction machine comprising a control means having a function of shutting off a signal output circuit to the receiving portion of the on-off valve and the second switching valve.