JP2724469B2 - 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 circuit that can automatically prevent the working device from lowering under its own weight when switching the inoperative state.

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. 3 shows an embodiment of a main part of a traveling vibration suppressing device provided in a wheel type tractor shovel as shown in FIG. 2 as a representative example of a wheel type construction machine. Accordingly, when the wheel-type tractor shovel travels on an uneven road surface, the working device 7 projects forward from the front axle, and its weight ratio is large, the axle is unbuffered, and the whole is supported by rubber tires. Therefore, vibration is easily generated.

In order to absorb the vibration energy at this time and make it a damped vibration, the load-side pipe 15a of the lift cylinder 8 supporting the working device 7 is connected to the slow return valve 18 including the throttle portion 18a and the check valve 18b, and the accumulator 19. The working device 7 is caused to vibrate separately from the vehicle body by communicating with the vibration suppressing device 20 composed of

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.

For this reason, a switch provided in the vicinity of the driver's seat is provided with an on-off valve 17 in the middle of a branch line 16 that connects the line 15a communicating with the head side oil chamber 8a on the load side of the lift cylinder 8 and the vibration suppressing device 20. 6 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,
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 at the position A in FIG. 3, so that the pipeline 15a and the vibration suppressing device 20 are shut 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 all the excavation operations of the earth and sand are completed and the traveling for traveling is started, the switch 6 is closed to connect the vibration suppressing device 20 and the pipe 15a for suppressing the vibration during traveling. Is not stored up to the pressure of the pipe 15a, a part of the pressure oil in the head side oil chamber 8a of the lift cylinder 8 is
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. When dumping earth and sand at a predetermined place after the next movement, the switch 6 is opened again to prevent the vehicle from shaking, and the pipe 15a is opened.
Communication with the vibration suppression device 20 is cut off, and the dump cylinder 9
To release the sediment from the bucket. As a result, the load on the working device 7 decreases, and the pressure in the pipeline 15a decreases accordingly. In this state, the movement of the vehicle is started. When the switch 6 is closed and the lift cylinder 8 and the vibration suppression circuit 20 are communicated with each other to suppress the vibration of the vehicle during traveling, the accumulator 19 is filled with the earth and sand. Since the high pressure of the head-side oil chamber 8a corresponding to the load of the head-side oil chamber 8a is stored as it is, a part of the pressure oil stored at the moment when the on-off valve 17 is switched to the position B becomes part of the head-side oil chamber of the lift cylinder 8. 8a, and the working device 7 is raised with respect to the vehicle body.

As described above, each time the on-off valve 17 is switched to the position B, the working device 7 slightly turns up and down against the driver's will, and it becomes difficult to maintain the correct bucket position required during the work. Hamper quick and safe work.

SUMMARY OF THE INVENTION In view of the above problems, when switching to the vibration suppression circuit state, the present invention always keeps the pressure in the head side oil chamber of the lift cylinder and the accumulated pressure in the accumulator the same, so that the working device does not need to use the vehicle body. The purpose of the present invention is to provide an inexpensive stabilizing circuit for preventing the above-mentioned vertical rotation.

Means for Solving the Problems In order to solve the above problems, the present invention employs the following means. That is, a. B. An on-off valve that is opened by an electric signal from the outside in a pipe connecting the vibration suppression device and the load-side oil chamber of the lift cylinder for the working device; It is in the middle of the pipeline connecting the hydraulic pump and the hydraulic switching valve for the working device, and is switched by a signal to supply the discharge pressure oil of the hydraulic pump to the hydraulic switching valve for the working device or directly to the vibration suppression device. A first switching valve for supplying the accumulator in the device until a predetermined pressure is accumulated, c. A second switching valve for connecting one of the receiving portions of the first switching valve to the tank by an external electric signal to connect the pipeline to the oil chamber on the load side of the lift cylinder; d. Means for actuating a limit switch when the pressure in the pipeline leading to the vibration suppression device is substantially equal to or higher than the load side pressure of the lift cylinder, for example, a switch cylinder; A power source is connected to the receiving portion of the on-off valve via a make contact having a function of closing the circuit by the operation of a switch and a limit switch operated by a switch cylinder and having a function of maintaining a closed state; A power source is connected to the receiving portion of the second switching valve via a break contact that opens through the switch at the same time as the make contact operates via the switch.

When the switch is closed when the working device is lifted by the lift cylinder to start traveling, the power supply acts on the receiving portion of the second switching valve via the switch and the break contact to switch the valve, and the first switching is performed. The conduit leading to one receiving part of the valve,
Connect to the pipeline leading to the load side oil chamber of the lift cylinder.
At this time, the pressure in the load-side oil chamber of the lift cylinder
When the pressure is higher than the pressure of the pipeline leading from the switching valve to the vibration suppressing device, the first switching valve is switched to the side where the hydraulic pressure discharged from the hydraulic pump is supplied to the vibration suppressing device. When the pressure is substantially equal to the load side pressure of the lift cylinder, the limit switch operates by the action of the switch cylinder, the make contact is closed, and the closed state is maintained. Power is continuously supplied to the unit, and the load-side oil chamber of the lift cylinder and the vibration suppression device communicate with each other via a pipeline and an on-off valve. At this time, since the pressure of the load-side oil chamber of the lift cylinder and the pressure of the vibration suppressing device are substantially equal, the operating device maintains its position even when the on-off valve is opened.

As soon as the make contact is activated, the break contact is opened and the operation of the second switching valve is stopped, so that the pipe leading to one of the receiving parts of the first switching valve is connected to the tank so that the valve is switched. The hydraulic pressure discharged from the hydraulic pump flows into the hydraulic switching valve for the working device.

Thus, the effect of suppressing the vibration of the vehicle body during traveling can be obtained, and it is of course possible to operate the working device. However, even when the open / close valve is operated, the working device may not be inadvertently lowered. Absent.

Next, when performing operations such as excavation, scooping, and discharge, it is more reliable and safer to operate the vibration suppressor without operating the vibration suppressor. Since the load-side oil chamber and the vibration suppression device are shut off by the on-off valve, powerful and reliable operation of the working device is realized.

At this time, since the second switching valve has a pipe communicating with one of the receiving portions of the first switching valve communicating with the tank, the discharge pressure oil of the hydraulic pump can be completely discharged through the first switching valve. It flows toward the hydraulic switching valve for the working device.

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 equipment, 10 is a tank, 11 is a hydraulic pump for operating working equipment and the like in a hydraulic power unit, and 12 is a hydraulic switching valve for dump cylinder 9. The line 14a,
The head-side oil chamber 9a and the rod-side oil chamber 9b of the dump cylinder 9 are connected via 14b, and 13 is a hydraulic switching valve for the lift cylinder 8, which is connected to the hydraulic switching valve 13 via pipes 15a and 15b. The head side oil chamber 8a and the rod side oil chamber 8b of the lift cylinder 8 are connected. Furthermore, in the lift cylinder 8, a branch line 16 is provided in the middle of a line 15a connected to the oil chamber on the load side by the working device, that is, the head side oil chamber 8a. Via throttle valve 18a and check valve 1
8b. The slow return valve 18 is further connected to an accumulator 19. The on-off valve 17 normally closes the branch line 16 by the biasing force of the built-in spring, and opens when the electric signal is input to the receiving portion thereof to open the branch line 16 and the slow return valve. The device is configured to communicate with a vibration suppressing device 20 including an accumulator 19 and an accumulator 19. In addition, as the accumulator 19, usually a Prada-type accumulator is used, and the load may be singular or plural depending on the size of the load, working conditions, installation space, or the like, or may be one or more including the on-off valve 17, the vibration suppression device 20, and the like. Various combinations may be used.

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

1 is a relay circuit having a make contact 2, a break contact 3, a switch 6 for opening and closing a power supply, and the like. The make contact 2 is normally open, but when the switch 6 is closed, a limit is applied. Once the electric wire 39 is closed by the switch 5, power is continuously supplied to the electric wire 40 leading to the receiving portion 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, regardless of whether the limit switch 5 is opened or closed, the electric circuit 40 is a known electric circuit that is open while the electric wire 40 is energized. Reference numeral 4 denotes a rod side having a head-side oil chamber 4a and a spring. A switch cylinder having an oil chamber 4b, which is normally contracted by the urging force of a spring, but expands when the pressure in the oil chamber 4a rises and becomes substantially equal to the oil chamber 4b pressure. The tip is the limit By acting on the actuator of the switch 5, the internal electric circuit of the limit switch 5 is closed, and the above-mentioned on-off valve 17 and the vibration suppressing device 20 are connected to the head side oil chamber 4a. A pipe 33 branched from the pipe is guided through a pipe 34, and a pipe 35 extending from the pipe 15a is guided to the rod-side oil chamber 4b.

Further, in the middle of the pipeline 32 in which the pressure oil of the hydraulic pump 11 flows into the hydraulic switching valve group including the hydraulic switching valves 12 and 13, a pipeline 37 is provided.
A first switching valve 30 is provided for switching to the C position by the signal pressure generated in the valve or to the D position by the signal pressure generated in the pipeline 41. When the first switching valve 30 is in the C position, The pressure oil discharged from the pump 11 is supplied to the pipe 33 via the check valve 29,
When switched to the position, the passage to line 33 is blocked and guided to line 32, and when the pressures in lines 37, 41 are approximately equal, the valve retains the C position. I do.

Numeral 31 denotes an electromagnetic type second switching valve, and an electric wire 38 leading to a power source via a break contact 3 is guided to a receiving portion thereof. Is switched to the F position when excited, and the pipe 37 is connected to a pipe 36 branched from the pipe 35.

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

When the wheel-type tractor excavator is stopped, or when digging, scooping, raising or lowering the work equipment, etc. under ultra-low speed operation, operate the hydraulic switching valves 12, 13 with the switch 6 open. In this case, the on-off valve 17 and the second switching valve 31 are not excited, so that the on-off valve 17 is at the position A and the branch line 16 and the vibration suppressing device 20 The second switching valve 31 is at the position E, and the pipe 37 is connected to the tank 10. On the other hand, the hydraulic pump 11 is already operating, and the discharge pressure oil thereof is supplied to the first switching valve 30.
Flows into the accumulator 19 through the C position passage, the check valve 29, the pipe 33, and the slow return valve 18, but because of the finite volume, it immediately fills up, the pressure in the pipe 33 rises, and at the same time the pipe 41 The pressure is also higher than that of the line 37, so that the first switching valve 30 is switched to the D position against the urging force of the spring and holds that position, and the discharge pressure oil of the hydraulic pump 11 is discharged to the first position. The fluid flows into the hydraulic switching valves 12 and 13 through the D-position passage of the switching valve 30 and the pipeline 32, and the lift cylinder 8 and the dump cylinder 9 are expanded and contracted by operating the switching valves. Therefore, in this state, the working device 7 is
As a result, the vehicle is reliably supported by the vehicle body, and performs an accurate operation in accordance with the operation of the hydraulic switching valves 12 and 13 as in a normal machine.

When the scooping of the earth and sand into the bucket is completed and the traveling on the undulating transport path is started, the switch 6 is closed first and the hydraulic switching valves 12 and 13 are operated to adjust the traveling posture. During this time, the power supply is switch 6, break contact 3, electric wire
Since the valve passes through 38 and acts on the receiving portion of the second switching valve 31, the valve is switched from the E position to the F position, and the pipe 37 which has been connected to the tank 10 up to that point is connected to the pipe 36, 1 switching valve 30
When the pressure of the pipe 37, that is, the pipe 16a is higher than the pressure of the pipe 41, that is, the pressure of the accumulator 19, the position C is maintained, but the discharge pressure oil of the hydraulic pump 11 flows into the accumulator 19 through the pipe 33. When the pressure in the line 41 becomes higher than that in the line 37, the pressure is switched to the position D, and the discharge pressure oil of the hydraulic pump 11 passes through the line 32 and the hydraulic switching valves 12, 1
Flow into 3. On the other hand, the line 34 leading to the head side oil chamber 4a of the switch cylinder 4 is at the same time equal to the pressure of the accumulator 19, and the line 35 leading to the rod side oil chamber 4b is connected to the head side oil chamber 8a which is the load side of the lift cylinder 8. When the pressure in the head-side oil chamber 4a gradually increases due to the pressure of the hydraulic pump 11 and becomes substantially equal to or higher than the pressure in the rod-side oil chamber 4b, the switch cylinder 4 is provided with a built-in spring. , And the end of the rod acts on the actuator of the limit switch 5 to close the internal electric circuit of the limit switch 5, so that the electric wire 39 is short-circuited. Accordingly, the power supply passing through the switch 6 excites the make contact 2 via the limit switch 5, so that the make contact 2 is closed, and the power is supplied to the receiving portion of the on-off valve 17 via the electric wire 40 connected thereto. Is connected, the on-off valve 17 is switched from the A position to the B position, and the pipeline 16 is connected to the accumulator through the on-off valve 17 and the slow return valve 18.
19, and exerts a vibration suppressing effect. However, when the on-off valve 17 is switched, as described above, the working chamber 7 is in the same state as the pressure in the oil chamber 8a and the accumulator 19 is substantially the same. It does not descend temporarily.

When the make contact 2 is closed and power is supplied to the electric wire 40, the make contact 2 is provided with a holding function irrespective of the opening and closing of the limit switch 5, so that unless the switch 6 is opened, When the power is supplied to the electric wire 40, the break contact 3 is opened and the second switching valve 31 is not excited, so that the valve is switched to the original E position. 30 keeps the D position as long as the load pressure is present in the pipeline 33, and does not hinder the operation of the working device.

To summarize the above operation, with the switch 6 open,
When the machine is operated, the running vibration suppression device does not operate and exhibits the conventional standard performance. When the switch 6 is closed, when the internal pressure of the accumulator of the vibration suppressing device at that time is lower than the load side pressure of the lift cylinder, the accumulator is automatically turned on first by the discharge pressure oil of the hydraulic pump. After accumulating the pressure and making the two pressures approximately the same, the load-side oil chamber of the lift cylinder is connected to the vibration suppression device.

Effect of the Invention If the stabilizing circuit according to the present invention is provided in addition to the traveling vibration suppressing circuit of the hydraulic means provided in the wheel type construction machine, the hydraulic circuit in a normal working state can be switched to a circuit exhibiting the vibration suppressing effect. In advance, the hydraulic pressure of the oil chamber of the hydraulic cylinder for supporting the working device and the hydraulic pressure accumulated in the accumulator in the vibration suppression circuit are almost the same, so that the working device And the accumulator pressure automatically accumulates according to the weight of the working equipment including the symmetrical elephant.No special operation is required, and safe and stable work is possible. it can.

[Brief description of the drawings]

FIG. 1 is an electric / hydraulic system diagram showing an embodiment of the present invention, FIG. 2 is an external side view of a wheel-type tractor shovel, and FIG. 3 is a main part of a conventional traveling vibration suppressing device provided in a wheel-type tractor shovel. It is an electric and hydraulic system diagram. 1 relay circuit 2 make contact 3 break contact 4 switch cylinder 5 limit switch 17 on-off 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 of a working device support member is pivotally supported on a vehicle body and supported by a lift cylinder, wherein a pipe leading to a load side oil chamber of the lift cylinder is received. In a hydraulic traveling vibration suppression circuit connected to a vibration control device via an opening / closing valve that opens when a signal is input to the section, a signal is provided in the middle of the discharge side pipeline of an operating hydraulic pump such as various hydraulic actuators. And a first switching valve for supplying hydraulic oil to the hydraulic switching valve for actuating the actuator or supplying the hydraulic oil directly to the vibration suppressing device until a predetermined pressure is accumulated in the accumulator in the device. A second switching valve that issues a signal that switches the first switching valve to a side that supplies pressure oil to the vibration suppression device by an electric signal, and a pressure of a pipe leading to the vibration suppression device is substantially equal to a load pressure of the lift cylinder. Means for activating the limit switch when the value is equal to or greater than 0, and a power source is connected to the receiving portion of the on-off valve via a make contact having a function of closing and holding the switch by operating the switch and the limit switch. The above-mentioned switch is provided in the receiving section of the second switching valve.
A running vibration suppressing and stabilizing circuit for a wheel-type construction machine, characterized in that a power source is connected via a break contact that opens at the same time as a make contact operates.