JPH0513818Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention pivots the base end of a working device that protrudes from the vehicle body to the vehicle body so that it can move up and down, and is equipped with a hydraulic vibration suppression circuit. The above-mentioned vibration suppression technology is used to suppress the vibrations that occur in the vehicle body when a wheeled construction machine supported by a hydraulic cylinder runs on an uneven road surface, so that the characteristics are optimal for the load condition of the work equipment. The present invention relates to a device that automatically adjusts circuit characteristics.

BACKGROUND ART In wheel-type construction machinery, the working device is protruded from the front part of the vehicle body, and in rare cases at the rear thereof, and a hydraulic cylinder is provided to support the working device with respect to the vehicle body. It is provided between the two and expands and contracts to ensure that the workpiece is handled by the work device and to maintain a predetermined working or running posture. On the other hand, the vehicle itself is a so-called non-shock type vehicle, in which the frame on which the driver's seat, control device, work equipment, power plant, etc. are mounted is directly mounted on an axle with rubber tire wheels. The majority.

In recent years, these wheeled construction machines have seen dramatic improvements in their running performance, maneuverability, and running stability, as well as the diversification of types of work. It is more economical to move a heavy snow plow as a working device, such as a snow plow, and the demand for this is increasing, but this wheel-type construction machine If the vehicle continues to travel at a speed higher than that, the undulations of the road surface will cause undamped oscillations in the vehicle body, such as longitudinal and lateral vibrations, pitching, rolling, and yawing, resulting in large dynamic loads on the vehicle body and the road surface. This not only causes discomfort to the driver, but also causes discomfort and fatigue for the driver, leading to health problems and even erroneous operation.

The occurrence of this undamped vibration is basically strongly influenced by the position of the center of gravity of the entire vehicle, the wheelbase, the proportion of mass that overhangs and protrudes outward from the wheelbase, and the driving conditions. In practical terms, this is caused by a combination of the type, position, and weight of work tools such as bucket carts and snow plows, the magnitude of the load caused by the object being worked on, the degree of undulation of the road surface, and the traveling speed. Traditionally, as a method to suppress this vibration, when vibration occurs while driving under range driving conditions, the driving operation is done by changing the driving speed (mainly by switching to a lower speed), Alternatively, the machine is equipped with hydraulic means in advance, that is, the pressure oil pipe on the load side of the hydraulic cylinder that supports the working device is branched and communicated with the pipe of a vibration suppression circuit consisting of a slow return valve and an accumulator. method is taken.

Among these means, the former method leads to a decrease in work efficiency, and the latter hydraulic method is affected not only by the capacity of the accumulator and the initial gas pressure, but also by the throttling effect of the slow return valve. The vibration absorption energy characteristics of vibration suppression circuits naturally differ, and a vibration suppression circuit that only has certain characteristics will not be able to obtain characteristics suitable for each of the various operating load conditions as described above. will be far from achieving its objectives.

Problems that the invention aims to solve When using hydraulic means to suppress vibrations of wheeled construction machinery, if no load is applied to the working equipment, or if the workpiece is loaded, the original work tool as the working equipment In practice, it may be possible to drive under conditions such as when special work tools with different weights and center of gravity positions are attached. This could not be achieved with a slow return valve.

This idea is based on automatic adjustment that automatically changes the characteristics of the vibration suppression circuit according to the load condition of the work equipment in the changing driving conditions as described above, and provides the most favorable vibration suppression effect for each condition. This paper proposes a device.

Means for Solving the Problem In order to solve this problem, the present invention has the following configuration. In other words, the pipe line leading to the load-side oil chamber of the hydraulic cylinder that supports the work equipment is branched off, and the proportional hydraulic Equipped with a pilot type variable throttle valve,
In the receiving part of the proportional hydraulic pilot type variable throttle valve,
The pressure oil in the load-side oil chamber of the hydraulic cylinder is guided through the throttle.

Effect When the machine runs with the vibration suppression circuit connected, the pressure in the load-side oil chamber of the hydraulic cylinder increases or decreases in proportion to the moment generated from the relationship between the weight, payload, and center of gravity of the working equipment at that time, and at the same time The throttling effect of the proportional hydraulic pilot type variable throttle valve also increases or decreases, and the characteristics of vibration energy absorption in this vibration suppressing circuit change, making it possible to obtain a vibration suppressing effect with characteristics suitable for each state.

Example An embodiment of this invention will be described based on the drawings.

1 and 2 are external side views of a wheeled tractor shovel as a typical example of wheeled construction machinery. It shows the driving posture when the vehicle body 2 is installed.
are the same, but the working device 3 when the vehicle is empty when the bucket 5 is installed, when the vehicle is loaded, and when the snow removal plow is installed.
The distance l ₁ between the center of gravity position G and the center of the front wheel 1,
l ₂ , l ₃ and their weights are different.

This wheeled tractor shovel has a working device 3 mounted on a front frame 2a of a vehicle main body 2, which is mounted in a non-shocked manner on the axles of a plurality of wheels 1 using rubber tires. The working device 3 includes a boom 4 whose base end is rotatably supported on a front frame 2a, and a work tool such as a bucket 5 or a snow plow 6 rotatably supported at the tip of the boom 4. , a lift cylinder 8 provided between the front frame 2a and the boom 4, and a dump cylinder 9 provided via a link device between the front frame 2a and the power tool. .

FIG. 3 is a hydraulic system diagram of this wheeled tractor shovel, but it is also an electrical system diagram according to this invention. In this figure, 10 is a tank,
11 is a main pump for operating the working device in the hydraulic power unit, 12 is a hydraulic switching valve for the dump cylinder, and 13 is a hydraulic switching valve for the lift cylinder.
A pipe line 14a is connected to the hydraulic switching valve 12 for the dump cylinder.
The head side oil chamber 9a and rod oil chamber 9b of the dump cylinder 9 are connected through 14b, and the head side oil chamber 8a and rod side of the lift cylinder 8 are connected to the lift cylinder hydraulic switching valve 13 through pipes 15a and 15b. An oil chamber 8b is connected thereto. Further, a branch pipe 16 is provided in the middle of the pipe 15a connected to the oil chamber on the side of the lift cylinder 8 where the weight of the working device 3 is loaded, that is, the head side oil chamber 8a. , an electromagnetic on-off valve 17 that normally closes the internal oil passage (position A in the diagram) with the biasing force of a spring, and opens the circuit (position B in the diagram) when an electric signal is input to the receiver. A slow return valve 18 consisting of a proportional hydraulic pilot type variable throttle valve 18a and a check valve 18b is connected through the slow return valve 18, and an accumulator 19 is further connected to the slow return valve 18.

Note that the accumulator 19 is usually a Prada type accumulator, and may be used in various combinations depending on the load size, installation space, and other factors, such as capacity, intended gas pressure, and number of units used. . Also, the accumulator 19
A vibration suppression circuit 20 consisting of a and a slow return valve 18 is connected between the head side oil chamber 8a and the lift cylinder hydraulic 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 by using a connecting piping method.

Also, 21 is the main relief valve, 22, 2
3 and 24 are conduits 14a, 14b, and 15, respectively.
Overload relief valve of the circuit communicating with a, 2
5, 26, 27, and 28 are check valves for preventing cavitation.

Furthermore, the proportional hydraulic pilot type variable throttle valve 18a, which is the throttle section of the slow return valve 18, has a throttle effect that increases or decreases proportionally depending on the magnitude of the pressure signal acting on its receiving section C. The pressure oil in the pipe line 16 is transferred to the receiving part C by the pipe line 31.
It is guided through an aperture 7. 29 is a switch,
The power source 30 is led to the receiving part of the on-off valve 17 via the switch 29 and the electric wire 32, and by opening and closing the switch 29, the purpose is to connect/disconnect communication between the conduit 16 and the vibration suppression circuit. Therefore, the on-off valve 17 is not necessarily an electromagnetic on-off valve, but may also be a hydraulic pilot type, manual type, or other remote control type as long as it can easily open and close the internal oil passage whenever necessary. I don't mind it at all.

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

When carrying out excavation or loading work with a wheeled tractor shovel, the vehicle speed is very low or the vehicle is stationary, and it is not affected by the undulations of the road surface at all; rather, the working device 3 is The switch 29 is left open since it is necessary to maintain a secure relative position with the main body 2. At this time,
The on-off valve 17 is in the A position, and the head side oil chamber 8a of the lift cylinder 8 is connected only to the lift cylinder hydraulic pressure switching valve 13 through the pipe 15a, leaving the hydraulic circuit of the conventional wheeled tractor shovel unchanged. The working device 3 is securely held on the vehicle body 2.

Next, the machine starts moving to transport the excavated soil and transport it by itself. At this time, when the switch 29 is closed, the power supply 30 passes through the switch 29 and the electric wire 32 and acts on the receiving part of the on-off valve 17. Since the on-off valve 17 is switched from the A position to the B position to open the internal oil passage, the pipe line 15a is connected to the branch pipe line 1.
6. The opening/closing valve 17 is connected to the pipe line of the vibration suppression circuit 20 through the B position passage, and the working device 3 is supported by the lift cylinder 8 which is also equipped with the vibration suppression circuit 20, thereby suppressing the vibration of the vehicle body. be done. However, as mentioned before, the vibration suppression circuit 2
0 does not have characteristics commensurate with the weight and center of gravity position of the working device 3, vibration energy will not be absorbed appropriately and the effect cannot be expected.
In the present invention, the pressure oil in the pipe line 16, that is, the pressure oil in the head side oil chamber 8a that is generated in proportion to the weight moment of the working device 3, is passed through the pipe line 31 and the throttle 7.
Since it is led to the receiving part C of the proportional hydraulic pilot type variable throttle valve 18a, the throttling effect of the proportional hydraulic pilot type variable throttle valve 18a increases and decreases gradually.
Furthermore, the characteristics of the vibration suppression circuit 20 are changed proportionally so that the vibrations of the vehicle body 2 are suppressed in response to changes in the weight of the working device 3.

In this way, when this device is installed on a wheeled construction machine similar to a wheeled tractor shovel, the vibrations generated when traveling on an uneven road surface at a certain speed or higher can be reduced during the work at that time. It is absorbed by a vibration suppression circuit whose characteristics change depending on the weight of the device.

FIG. 4 is an electrical/hydraulic system diagram showing the waist part of the second embodiment of this invention, 34 is a vibration suppression circuit consisting of a slow return valve 33 and an accumulator 19, and the slow return valve 33 is a check valve. 18b and a proportional electromagnetic variable throttle valve 33a, which is a throttle part, and an electric signal is sent to the receiving part D of the load cell 36, which detects the load of the lift cylinder 8, through an amplifier 35 and an electric wire 37. It is guided as follows. In the first embodiment, the throttling effect of the slow return valve 18 is increased or decreased by a hydraulic signal, but in the second embodiment, the proportional electromagnetic Variable throttle valve 33a
The aperture effect is increased or decreased, and other configurations and operations are the same as in the first embodiment.

In addition, the receiving part D of the proportional electromagnetic variable throttle valve 33a
In addition to the detected value of the load on the lift cylinder 8 shown in this second embodiment, for example, the pressure in the head side oil chamber 8a of the lift cylinder 8 may be converted into an electrical signal and guided to the work equipment. This purpose can be achieved even with electrical signals obtained by detecting the types and states of 3.

Effects of the invention This invention was developed as a throttle part of the slow return valve that constitutes the vibration suppression circuit of wheeled construction machinery. The signal is input to the receiver and we use a proportional variable throttle valve that increases or decreases the throttle effect, so the vibration suppression effect is always automatically adjusted to suit each load condition, making it easier to use while driving. It is effective in improving riding comfort, reducing driver fatigue, and maintaining health, and is also easy to operate.

[Brief explanation of the drawing]

Figure 1 shows the state when the bucket is attached, and the second figure.
The figure is an external side view of a wheeled tractor shovel with a snow removal plow attached, Figure 3 is an electric/hydraulic system diagram of a wheeled tractor shovel equipped with the device of the present invention, and Figure 4 is a diagram of the wheeled tractor shovel equipped with the device of the present invention. It is a principal part electric/hydraulic system diagram of 2nd Example. 3... Working equipment, 5... Bucket, 6... Snow removal plow, 7... Throttle, 17... Opening/closing valve, 18,3
3... Slow return valve, 18a... Proportional hydraulic pilot type variable throttle valve, 19... Accumulator, 20, 34... Vibration suppression circuit, 33a... Proportional electromagnetic variable throttle valve.

Claims (1)

[Scope of utility model registration request] In wheel-type construction machinery, in which the base end of the working equipment is pivotally supported on the vehicle body, and the hydraulic cylinder supports the working equipment's own weight and work load, and performs predetermined rotational movements, the oil on the load side of the hydraulic cylinder is A hydraulic vibration suppression circuit is constructed by connecting a pipe line leading to the chamber to an accumulator via a slow return valve consisting of a variable throttle valve and a check valve, and a hydraulic vibration suppression circuit configured by connecting a pipe line leading to the chamber to an accumulator through a slow return valve consisting of a variable throttle valve and a check valve, and a hydraulic vibration suppression circuit configured to connect the pipe line leading to the chamber to the accumulator via a slow return valve consisting of a variable throttle valve and a check valve. a variable throttle valve that increases or decreases its throttle effect in proportion to the magnitude of the signal, and a receiving section of the variable throttle valve;
and means for supplying an electrical or hydraulic signal proportional to the load moment determined by the load condition of the working device.