JPH0513815Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention is a wheeled construction machine in which the working device is articulated and protrudes from the vehicle body. While driving, the action of the hydraulic cylinder automatically dampens the vertical, longitudinal, and horizontal vibrations of the vehicle body, as well as pitching, rolling, and yawing, improving ride comfort and driving operation. This invention relates to an automatic vibration suppression device that improves performance.

Conventional technology In wheel-type construction machinery, the working device is installed on the vehicle body, mostly in the front, and rarely in the rear, in a jointed state, and the entire working device can be rotated up and down around the joint. In order to maintain a fixed position, a hydraulic cylinder or the like is installed between the working device and the vehicle body. A hydraulic cylinder or the like with a large capacity is used to ensure that the workpiece is handled by the work device and maintained in a predetermined working or running position. On the other hand, due to the nature of the work, the above-mentioned working equipment has conventionally been of a sturdy construction and tends to increase in weight, and the position of the center of gravity of the entire vehicle is largely influenced by the position and weight of the working equipment.

In particular, in recent years, wheel-type construction machinery has seen dramatic improvements in running performance, maneuverability, and running safety, as well as the diversification of work types. It is more economical to carry out transportation between work sites, or to transport the materials by self-propelled transport between work sites, and there are many requests for this.

As a result, the vehicle is often driven with the working equipment, which accounts for a large proportion of the total vehicle weight including the working equipment or the work object, firmly attached to the vehicle body. Moreover, in general, compared to automobiles, which are primarily designed for running, wheeled construction machines place importance on maneuverability in narrow work sites, so the wheelbase is as small as possible, and the structure of the machine necessitates a high center of gravity.

For example, as a representative example of a wheeled construction machine, the main structure of a wheeled tractor shovel shown in FIG. 1 will be explained. The working device 3 is attached to the front frame 2a of the machine. The working device 3 includes a boom 4 whose base end is rotatably supported by the front frame 2a in an articulated manner.
a bucket 5 rotatably supported at the tip of the boom 4; a cross link 6 and a dump link 7 bendably connected between the middle part of the boom 4 and one side of the bucket 5; Above front frame 2
It is comprised of a lift cylinder 8 provided between the front frame 2a and the boom 4, a dump cylinder 9 provided between the front frame 2a and the cross link 6, and the like.

The wheeled tractor shovel as described above is
When driving at a speed above a certain level on a ground surface 30' with uneven parts or a road surface with a wavy surface as shown in the figure, in the example shown in the figure, the front wheel 1 moves on the ground surface 30'.
The rear wheel 1 runs onto the convex part and is lifted higher than the rear wheel 1, and the forward axis of the machine tilts diagonally upward.Then the rear wheel 1 runs onto the convex part, and the machine's axis of travel tilts backwards. tilts diagonally downward and swings. Swinging of such a machine is not limited to just the front and back directions, but also when one of the left and right wheels of the wheels 1, 1 is on the ground 3.
When the vehicle enters the uneven portion of 0', it swings in the left-right direction perpendicular to the direction of travel. It is not only impossible to avoid the uneven parts that cause the above-mentioned oscillations on the work site, but also on general public roads, which are smooth but have undulations, so the running speed of the wheeled tractor shovel As the value increases, a phenomenon similar to that described above occurs. put it here,
As mentioned above, a wheeled construction machine such as the wheeled tractor shovel shown as an example has a relatively short wheelbase, a high center of gravity, and is also provided with suspension springs to absorb the vertical movement of the wheels 1, 1. the boom 4, while the work equipment 3 is traveling
Since it is firmly fixed to the front frame 2a of the vehicle body 2 by the lift cylinder 8, the working device 3 oscillates integrally with the vehicle body 2 in terms of swing, amplitude, and period. It happens.
Therefore, when driving at high speeds, the wheels 1, 1 move over irregularities on the road surface and the ground at a certain interval in response to the single natural frequency of the entire machine supported by elastic pneumatic rubber tires. When the machine runs over or falls over, it is added to the natural vibration of the entire machine, and the amplitude appears as undamped vibration, which continues to vibrate for a long time or increases as long as the running speed is within a certain range. There is a tendency to

Continuing to drive in such a state not only results in poor ride comfort, but also poses a danger that may lead to erroneous driving operations, and even if this is not the case, the operator is highly fatigued.

In recent years, in order to prevent this vibration, the lift cylinder 8 that holds the working device 3 in a fixed position in FIG. There is a machine that is supported by the vehicle body 2 and is designed to eliminate the vibrations of the vehicle body 2 separately so that the vibration of the entire machine always becomes a damped vibration.

There are several methods for forcibly generating this damped vibration, but the first example is JP-A-59-
As disclosed in Japanese Patent No. 182195, a mobile crane is known in which a spring (auxiliary spring) and a damper mechanism are provided inside the piston rod of a boom hoist cylinder. In this device, the piston rod of the hoist cylinder is formed hollow, and many members such as an auxiliary piston, a metal spring, a spring guide, and a support ring are built into the rod. ₂ Gas must be sealed.

Also, as a second example, for example,
As shown in Publication No. 11930, the boom of the hydraulic excavator is installed between the arm cylinder or between the arm and the bucket cylinder, and a buffer cylinder is installed separately from the working hydraulic cylinder such as the arm cylinder or the bucket cylinder. It is known that there is a

Problems that the invention aims to solve As mentioned above, vibration suppression methods have been developed in recent years, such as making the hydraulic cylinder that supports the working equipment have a special structure, adding auxiliary devices that separately absorb and damp vibrations, or using vibration suppression methods. Countermeasures such as providing a suppressing auxiliary hydraulic circuit have been proposed, but in the first example, the vibration damping constant is determined by the constant of the spring for vibration reduction and the properties of the orifice, so it is easy to It cannot be changed, and it is very difficult to set constants, and the structure is complex and manufacturing costs are high.In addition, in the second example, the components of the tip of the working device resonate with the vehicle body while driving. The purpose is to suppress the vibration of the entire machine, but it has little effect on suppressing the vibration of the entire machine.

In view of the above, this invention has a simple structure, low cost, and can be easily applied to conventional machines.Furthermore, during work using the work equipment, the vehicle body and work equipment can be reliably maintained under hydraulic pressure. The present invention aims to provide an automatic vibration suppressing device that is held by a cylinder and automatically switches to a circuit that damps the vibrations of the entire machine when the machine is running.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention has the following configuration. In other words, (a) An accumulator is connected in series with an electromagnetic switching valve and a slow return valve to a branch pipe of a hydraulic pipe on the load side of a hydraulic cylinder that supports a working device articulated on the vehicle body of a wheeled construction machine. (b) The above-mentioned electromagnetic switching valve is a solenoid switching valve that normally closes the internal oil passage by the biasing force of a built-in spring, and opens the internal oil passage when an electric signal is input to the receiving section from the outside. None, C. An acceleration detector is fixedly installed on the vehicle body to detect acceleration in the vertical direction perpendicular to the direction of travel; D. An amplification device that amplifies the output of the acceleration detector;
A relay is provided which closes the main electric circuit when an electrical signal equal to or higher than the closing value is applied to the relay circuit, and (e) the output section of the amplifier is guided to the relay circuit of the relay, and (f) the receiving section of the electromagnetic switching valve is provided with a relay. Connect the power supply via the above relay.

How it works When a vehicle travels on uneven ground and its speed increases, the vehicle body begins to vibrate, as mentioned earlier, and each part gradually shakes violently up and down.

At this time, an acceleration detector mounted on the vehicle body detects acceleration in the vertical direction. This detected value is amplified by an amplifier and acts on the relay circuit, and when the value exceeds a predetermined value, the main electrical circuit of the relay is closed and the power is connected to the solenoid directional valve, so the inside of the solenoid directional valve is The oil passage is opened, and the load-side hydraulic line of the hydraulic cylinder that supports the working equipment is communicated with the accumulator via a branch line, an electromagnetic switching valve, and a slow return valve, and the working equipment is separated from the vehicle body by vibration. In addition, the vibration energy is absorbed and becomes damped vibration, and as a result, the vibration suppression effect of the entire machine can be obtained without any special operation. Also,
When the vehicle is running at low speed or stopped, the output of the acceleration detector decreases, the main electrical circuit of the relay opens, and the internal oil path of the electromagnetic switching valve closes, ensuring that the work equipment is supported by the vehicle body. .

Embodiment FIG. 1 shows a side view of a wheeled tractor shovel as a representative example of a wheeled construction machine to which this invention is applied, and the main structure of this machine is as described above. The electrical and hydraulic system diagram of the main parts of the wheeled tractor shovel is shown in Figure 3. In this figure, 10 is a tank, 11 is a hydraulic pump for operating a working device in a hydraulic power unit, 12 is a hydraulic switching valve for a dump cylinder, 13 is a hydraulic switching valve for a lift cylinder, and 12 is a hydraulic switching valve for a dump cylinder. A head side oil chamber 9a and a rod side oil chamber 9b of the dump cylinder 9 are connected to each other via pipes 14a and 14b, and a head side oil chamber 9a and a rod side oil chamber 9b of the lift cylinder 9 are connected to each other via pipes 15a and 15b. Oil chamber 8a, rod side oil chamber 8
b is connected. Further, in the lift cylinder 8, a branch pipe 16 is provided in the middle of the pipe 15a connected to the oil chamber on the side where the weight of the working device 3 is loaded, that is, the head side oil chamber 8a. Variable throttle section 1 via electromagnetic switching valve 17
A slow return valve 18 consisting of a check valve 8a and a check valve 18b is connected to the slow return valve 18.
An accumulator 19 is connected to. In addition,
As the accumulator 19, a plug-type accumulator is usually used, but depending on the load size, installation space, and other factors, various combinations may be used, such as the sealed gas pressure and the number of units used, such as one or more. Accumulator 19 and slow return valve 18
The vibration suppression circuit 20 is connected between the head side oil chamber 8a of the lift cylinder 8 and the lift cylinder hydraulic pressure switching valve 13 by external piping including pipes 15a and 16. Therefore, the above-mentioned accumulator 19 and the like may be installed at any position on the front frame 2a within a range that does not interfere with the rotation of the boom 4 and the expansion and contraction operations of the lift cylinder 8, and depending on the connection piping method.

In addition, 21 is the main relief valve 22, 23, 2
4 are overload relief valves 25, 2 of the circuits communicating with the pipes 14a, 14b, and 15a, respectively;
6, 27, and 28 are check valves for preventing cavitation.

Furthermore, in this invention, on the vehicle body 2,
For example, an acceleration detector 29 for detecting acceleration in the vertical direction is fixedly installed on the front frame 2a,
The detected value is connected to an amplifier 36 via electric wiring 37, and its output is communicated to a relay circuit 35 for operating the relay 32. This relay 32 closes the main electric circuit when an electric signal of a predetermined value or more is applied to the relay circuit 35, and is normally open.
The output part is connected to the electromagnetic switching valve 17 by electrical wiring 31.
A power supply 33 is connected to the receiving section of the receiver via a switch 34 on the input side.

As shown in the figure, when the electromagnetic switching valve 17 is not energized, it is held in the A position by the biasing force of a built-in spring and blocks the pipe line 16, but when it is energized, it is switched to the B position and the pipe line 16 is blocked. 16 and accumulator 1
9 through a slow return valve 18.

Next, the operation will be explained based on the embodiment of this invention having the above configuration.

When carrying out excavation and loading work with a wheeled tractor shovel, the working device 3 is lowered and the bucket 5 is
When the bucket 5 is filled with earth and sand, the working device 3 is raised by the lift cylinder 8, and the bucket 5 is adjusted to an angle that prevents the earth and sand from flowing out. The robot then moves forward or backward to a designated location and releases soil. In this way, the traveling speed of the vehicle during excavation and loading work in relatively narrow spaces is approximately several kilometers per hour, but when the distance of transporting earth and sand becomes long, or when the vehicle is transported by self-propelled, , the traveling speed is increased in order to shorten the time required. In this way, even if the switch 34 is closed during excavation or loading work, the vibration of the vehicle body 2 is small when the traveling speed is low, so the value of the output electric signal of the acceleration detector 29 is small. Since the electrical signal of the relay circuit 35 does not reach the point of activating the relay 32, the main electrical circuit of the relay 29 remains open, and the electromagnetic switching valve 17 also remains in the A position. In other words, drilling
While loading, moving short distances, or driving on rough roads,
While the vehicle running speed is low and the vertical acceleration of the vehicle body 2 is small, the branch pipe 16 is closed to the electromagnetic switching valve 1.
7, the head side oil chamber 8a of the lift cylinder 8 that supports the working device 3 and the lift cylinder hydraulic switching valve 13 are connected to the pipe line 15.
a, and the branch pipe 16 is directly connected to the electromagnetic switching valve 1.
7, the state of the hydraulic circuit supporting the working device is the same as that in a normal wheeled tractor shovel, and when the lift cylinder hydraulic switching valve 13 is in the neutral position, the front frame of the vehicle body 2 is closed. A working device 3 is firmly connected to 2a.

Next, when carrying earth and sand loaded in the bucket 5 over medium distances, or when transporting the machine by self-propulsion, the gear shift lever (not shown) etc. should be moved to a high speed in order to shorten the time required. When driving at high speed by switching to the lower gear, if the road surface is uneven, the vehicle body will vibrate violently up and down.
As the detection value of the acceleration detector 29 increases, the main electric circuit of the relay 32 is closed, and the electromagnetic switching valve 17 is switched from the A position to the B position by the power supply 33.

In this state, as the wheeled tractor shovel travels, the vehicle body 2 vibrates in response to the undulations of the road surface and rapid acceleration/deceleration, causing the working device 3 to vibrate, and the boom 4 supporting the working device 3 to vibrate. The boom 4 is about to rotate in the vertical direction, causing pressure fluctuations in the head side oil chamber 8a of the lift cylinder 8 that supports the boom 4. In such a case, the head side oil chamber 8
a is the pipe line 15a, the branch pipe line 16, and the electromagnetic switching valve 1
7. Since it is linked to the accumulator 19 via the slow return valve 18, pressure oil flows into and out of the accumulator 19. At this time, the vibration is suppressed by the damping effect of the variable throttle portion 18a of the slow return valve 18, and the riding comfort is also improved.

That is, according to the wheel type shovel loader described above, it can be considered as a dynamic vibration damper in which the vehicle main body 2 side is the main vibration system and the working device 3 side, which is smaller in weight (mass) than the vehicle main body 2, is the sub vibration system. By selecting the capacity of the accumulator 19 and the pressure of the filled gas so that the natural frequency of the auxiliary vibration system on the working device 3 side is approximately equal to the natural frequency of the main vibration system on the vehicle main body 2 side. When traveling, the vehicle main body 2 hardly vibrates, but the working device 3 side of the sub-vibration system vibrates, and the spring force, that is, the accumulated pressure of the accumulator 19, is always applied from the ground 30 and the road surface on the working device 3 side. At the same time, the variable throttle portion 18a exhibits a vibration damping effect, thereby greatly and quickly suppressing vibrations and improving riding comfort.

In addition, the size of the mass of the vehicle body 2 and the working device 3,
Of course, greater effects can be expected by selecting and using an accumulator and slow return valve that match the load on the work equipment 3, road surface conditions that cause vibration, and machine usage conditions. Variable throttle section 18 within valve 18
A is not necessarily limited to a variable type, but it is also possible to find a value that suits the operating conditions of the machine and obtain the most vibration damping effect, and replace it with a fixed throttle part. Furthermore, when the vehicle main body 2 and the working device 3 are required to always be integral and move in the same manner even when traveling at high speed, for example, by keeping the power switch 34 open, The electromagnetic switching valve 17 always maintains the A position,
Needless to say, the branch pipe line 16 is blocked.

FIG. 4 is an electric circuit diagram showing a second embodiment of this invention, in which a relay 38 having a time-limited break contact function is provided between a relay circuit 35 connecting an amplifier 36 and a relay 32. The other parts not shown in the drawings are the same as those in the third embodiment of the first embodiment.
It is exactly the same as the figure. The purpose of this second embodiment is to further ensure the vibration suppression effect, and after the vibration of the vehicle body 2 falls below a predetermined acceleration, the lift cylinder 8 is The working device 3 is supported by the working device 3, and its operation is the same as that of the first embodiment.

Effects of the invention When the device of this invention is installed on a wheeled construction machine, while the wheeled construction machine is working and traveling at low speed, the working equipment is integrated with the vehicle body by the lift cylinder as before. held, transported and
When the vehicle body vibrates during high-speed driving such as forwarding, the vibration suppression circuit automatically switches to supporting the working equipment, so there is no vibration in the vehicle body even at high speeds, and the driver is free to operate or steer the working equipment. The driver only needs to concentrate on operation, and the ride quality is good, reducing driver fatigue, ensuring safety and improving work efficiency. In addition, if you do not need a vibration suppression circuit, you can simply operate a switch.
One machine can be used for multiple purposes.

Furthermore, all the equipment constituting this invention is general-purpose, and there is a high degree of freedom in selecting the installation location, making it easy to add additional equipment to existing machines and also economically advantageous.

[Brief explanation of the drawing]

Figure 1 is a side view showing the configuration of a wheeled tractor shovel, Figure 2 is a side view of the wheeled tractor shovel while it is running, Figure 3 is an electric/hydraulic system diagram of this invention, and Figure 4 is a side view showing the configuration of the wheeled tractor shovel. FIG. 2 is an electrical system diagram of main parts showing a second embodiment of this invention. 3... Working device, 8... Lift cylinder, 13
... Hydraulic switching valve for lift cylinder, 17 ... Solenoid switching valve, 18 ... Slow return valve, 20 ... Vibration suppression circuit, 29 ... Acceleration detector, 36 ... Multiplier, 38 ... Relay.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) One end of the working device is attached to the vehicle body in an articulated manner, and a hydraulic cylinder supports the self-weight load and working load of the working device, or makes a predetermined rotational movement. In wheel-type construction machinery, the internal oil line is normally closed by the biasing force of a spring in the branch pipe of the pipe leading to the hydraulic cylinder on the side where pressure is generated due to the load of the work equipment, and an electrical signal is sent from the outside. The accumulator is connected via an electromagnetic switching valve that opens when a An acceleration detector that detects acceleration in the vertical direction perpendicular to A relay for closing the circuit is provided, the output part of the amplifier is guided to the relay circuit of the relay, and the receiving part of the electromagnetic switching valve and the power source are connected via the relay. Vibration suppressor. (2) Provide a relay that has the function of closing the main electrical circuit when an electrical signal of a predetermined value or more acts on the relay circuit, and opening the circuit after a certain period of time when the electrical signal acting on the relay circuit becomes less than the predetermined value. An automatic vibration suppression device for a wheeled construction machine as set forth in claim 1 of the utility model registration claim.