JP3153864B2 - Running vibration suppression device for wheel type construction vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration suppressor for a construction vehicle, such as a wheel loader, which absorbs vibration during traveling by a work machine operating hydraulic circuit provided in the work machine.

[0002]

2. Description of the Related Art FIG. 1 shows an external side view of a wheel loader. In the figure, A is a vehicle body, B is a bucket, C is a boom cylinder, D is a boom, E is a bucket cylinder, and W is a wheel. The bucket B is attached to the tip of a boom D that can be rotated up and down by a boom cylinder C. The bucket B is rotatable back and forth by a bucket cylinder E.

In the construction vehicle described above, the working machine protrudes greatly in front of the vehicle body. Therefore, when the vehicle travels with earth or sand loaded on a bucket or travels on uneven terrain, the vehicle body moves up and down. There is a problem that the ride comfort and driving operability are poor.

In order to improve the above disadvantage, the present applicant has proposed Japanese Utility Model Application No. Hei 2-1289 as shown in FIGS. According to the present invention, the accumulator 9 is connected via a solenoid valve 13 in the middle of a pipe connecting the work machine cylinder 4 and the work machine operation valve 11, and the electromagnetic valve 13
A speed switch 14, which is turned on when the exciting coil 13b is linked to a speedometer and reaches a preset speed,
By connecting to the power supply via the switches 16 and 17 which are turned on when the work implement control lever 15 is set to the neutral position, the work implement control lever 15 is set to the neutral position during traveling,
When the vehicle speed reaches a preset speed, the solenoid valve 13 is energized, the solenoid valve 13 is opened, the work machine cylinder 4 and the accumulator 9 are connected, and the work machine cylinder 4 and the accumulator 9 reduce vibration of the vehicle body. It was done.

[0005]

SUMMARY OF THE INVENTION The above-mentioned Japanese Utility Model Application No. Hei 2-128.
No. 9 partially solved the problems of the previous vibration reduction device, but still has the following problems. (1) The backgrading operation (see FIG. 4) cannot be performed during the operation of the vibration suppressing device. The reason is that the hydraulic pressure (indicated by P4 in FIG. 2) in the working machine cylinder (4 in FIG. 2) communicates with the tank, and the boom (D in FIG. 1) to be held by the piston rod of the working machine cylinder causes bag grading. This is because they cannot escape from the work load.

(2) When the vehicle is stopped and the front wheel is lifted by the bucket (the same attitude as in FIG. 4) and the vibration suppressor is turned on by mistake during inspection and maintenance, the above (1) and For the same reason, the boom extends and the vehicle body falls and is dangerous.

(3) The function of the vibration suppressing device is achieved by the spring constant of the accumulator (9 in FIG. 2) and the throttling effect by the pipe resistance. However, since the accumulator is used at the same time, at the moment when the vibration suppression circuit and the normal work machine circuit are switched (for example, the speed switch 14 in FIG. 2 is turned off), the bottom pressure H of the work machine cylinder 4 and the accumulator Until the gas pressure of the cylinder 9 is balanced, the hydraulic oil moves into the accumulator 9, causing a phenomenon that the working machine cylinder 4 contracts and the boom falls. However, the general use of wheel loaders is forward → excavation → discharge →
Assuming a series of reverse flows, dropping the boom in the middle of work impairs the operability of the work equipment, and particularly, dropping the boom at the moment of unloading can be caused by dump truck vessels and hoppers. There was a danger of damaging them.

(4) There is a prior art in which a pressure switch (not shown) is provided in an oil passage between the solenoid valve 13 and the working machine cylinder 4 in FIG. 2 to switch the vibration suppressing device. Since the pressure switch always receives a high bottom pressure (H in FIG. 2) even in a normal working circuit, a very high durability switch is required.

(5) When the vibration suppressing device is operated during the operation, a high pressure (H in FIG. 2) generated at the bottom of the working machine cylinder 4 is applied to the accumulator 9, and the accumulator 9 may be damaged.

[0010]

The present invention has been made in view of the above, and has the following four items. (1) In a vibration suppression device for a wheel-type construction vehicle in which vibration during traveling is absorbed by a work machine operating hydraulic circuit provided in the work machine device, an oil passage connecting an oil chamber on the bottom side of a boom cylinder and an accumulator. A first electromagnetic switching valve having a check valve, and a pressure switch, and a second valve having a check valve in an oil passage branched from an oil passage connecting the head side oil chamber and the work implement operating valve. The electromagnetic switch valve and a relay that operates in response to the operation of the pressure switch and the operation of the vibration suppression device operation switch, so that the action of the pressure switch and the relay during scooping or in the process of raising the boom is provided. This automatically switches from the vibration suppression circuit to the normal work machine circuit. In addition, at this time, the boom does not fall due to the action of the first solenoid-operated directional control valve, and the high pressure oil during the work It is not applied.

(2) Since the pressure switch in the above (1) is provided in the oil passage connecting the head side oil chamber and the work implement operating valve, the pressure switch can be used during back-rading work or when the front tires are lifted. Even if the vibration suppression device operation switch is turned on by mistake during maintenance and repair inspection, the vibration suppression device does not operate and the vehicle body can be prevented from falling.

(3) In the above (2), by providing a second accumulator at the oil discharge port of the second electromagnetic switching valve, in the above (2), the operation switch of the vibration suppressing device is turned off during the backgrading operation. After that, manual operation for lifting the front wheel was necessary, but according to the means (3), this need is eliminated.

(4) In place of the pressure switch described above, a safety lever for restricting the operation of the working machine lever,
By providing a safety switch that is turned on and off by the operation of the lever, the safety lever is set to the release position at the time of work. When the operation switch is turned on, the vibration suppressing device is operated by turning the operation switch to the lock position, but the work implement operation valve cannot be operated.

[0014]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 5 is a diagram for explaining the electrohydraulic system of the first embodiment, in which devices having the same functions as in FIGS. 2 and 3 showing a conventional device are denoted by the same reference numerals. In the figure, when the vibration suppression operation switch 21 is turned on, the current from the power supply 18 passes to the relay 22 and the pressure switch 23. When the work machine operation valve 11 is operated, the pressure oil from the hydraulic pump 10 enters the bottom oil chamber 4b or the head oil chamber 4a of the boom cylinder 4 and causes the boom cylinder 4 to expand and contract.
An electromagnetic switching valve 26 is provided in an oil passage 25 branching from the middle of an oil passage 24 connecting the work machine operation valve 11 and the bottom oil chamber 4 b and connecting to the accumulator 9. Connected. Boom cylinder 4
An electromagnetic switching valve 29 is connected to an oil passage 28 branching from the middle of an oil passage 27 that connects the head side oil chamber 4a and the work implement operation valve 11 to each other.
Is provided. The current from the relay 22 passes through the solenoids of the electromagnetic switching valves 26 and 29. The set pressure of the pressure switch 23 is set so as to be higher than the oil pressure of the bottom oil chamber 4b of the boom cylinder 4 after discharging (hereinafter abbreviated as "bottom pressure").

Next, the operation of the first embodiment will be described. (1) The bottom pressure of the boom cylinder 4 increases when the vibration suppression operation switch 21 is turned on, that is, when the circuit is scooped or the boom rises while the circuit is in the vibration suppression circuit operation state. The hydraulic oil in the bottom side oil chamber 4b is supplied to the oil passages 24 and 25 and the electromagnetic switching valve 2
6, the accumulator 9 is filled through the open position 26a, and continues until the accumulated pressure reaches the set pressure of the pressure switch 23. When the accumulated pressure reaches the set pressure, the pressure switch 23 operates to activate the relay 22, and the electromagnetic switching valve 26 and 29 are turned off, and the circuit automatically switches from the vibration suppression circuit to the normal work machine circuit. After switching to the normal work machine circuit, the check valve at the closed position 26b of the electromagnetic switching valve 26 shuts off the oil passage from the bottom side of the boom cylinder 4 to the pressure switch 23 and the accumulator 9, so that the operation time is high. The circuit will be protected from hydraulic pressure.

(2) When the soil is discharged from the above state, the bottom pressure of the boom cylinder 4 decreases. At this time, the operating oil pressure in the accumulator 9 is reduced to the closed position 26b of the electromagnetic switching valve 26.
The pressure switch 23 is turned off again, and the electromagnetic switching valves 26 and 29 are turned on (open positions 26a and 29a) by the action of the relay 22. Automatically returns to the vibration suppression circuit. At this time, since the bottom pressure of the boom cylinder 4 is smaller than the internal pressure of the accumulator 9, the hydraulic oil in the bottom oil chamber 4b of the boom cylinder 4 does not enter the accumulator 9, so that the boom does not fall down which is a disadvantage of the related art. .

FIG. 6 is an electrohydraulic system diagram of the second embodiment. The difference from FIG. 5 of the first embodiment is that the hydraulic pressure applied to the pressure switch 23 is lower than that of the boom cylinder 4 in the first embodiment. Oil passage 25 branched from oil passage 24 from oil chamber 4b
In the second embodiment, the oil path 27 branches from the head-side oil chamber 4a.

The operation of the second embodiment is performed when the work implement is stretched to lift the front wheel during backgrading (see FIG. 4) and the vibration suppression device operation switch 21 is turned on by mistake during the operation. However, the head side oil chamber 4a
When the hydraulic pressure becomes equal to or higher than the set pressure of the pressure switch 23, the circuit to the electromagnetic switching valves 26 and 29 is automatically cut off by the relay 22, and the vibration suppressing device does not operate. .

In addition, even when the front wheel tire is replaced at the site, maintenance, repair, and inspection with the front wheel raised by a work machine, the vehicle body is prevented from falling even if the vibration suppression device operation switch 21 is accidentally turned on. Is what you can do.

FIG. 7 is a view showing a main part of an electro-hydraulic system according to a third embodiment. The difference from the second embodiment shown in FIG. 6 is that an oil passage 27 from a head side oil chamber 4a is provided. Another oil is connected to the oil outlet of the electromagnetic switching valve 29 provided in the branched oil passage.
Of accumulators 31 and the third
The operation of the second embodiment is almost the same as that of the second embodiment. However, in the case of the background grading operation, the second embodiment requires a manual operation of turning off the vibration suppression device operation switch 21 and then lifting the front wheel. However, in the third embodiment, even if the operation switch 21 is on, the accumulator 3
1, the high pressure in the head side oil chamber 4a is maintained, so that the front wheels can be floated.

FIG. 8 is a mechanical / electric / hydraulic system diagram of the fourth embodiment, which differs from the first embodiment shown in FIG. , A safety lever 32 and a safety switch 33 which is turned on / off by the movement of the lever 32. At the time of operation, the safety switch 33 is turned on by setting the safety lever 32 to the release position shown by the two-dot chain line in FIG.
6 and 29 are in the closed positions 26b and 29b, and the vibration suppressing device does not operate even if the operation switch 21 is turned on by mistake.
When the accumulator 9 is protected from the high pressure generated in the boom cylinder bottom chamber 4b during operation, and the safety lever 32 is in the locked position shown by the solid line in FIG.
When the safety switch 33 is turned off, the operation switch 2
When the switch 1 is turned on, the vibration suppression device operates, but the work implement lever 31 is suppressed by the safety lever 32, and the work implement operation valve 11 cannot be operated.

In the fourth embodiment, the vibration suppression operation switch 21 can be omitted from the system shown in FIG. 8, and in this case, the suppression device is operated only by operating the safety lever 32, or The accumulator 9 can be made inoperative, and at the time of operation, the movement of the work implement lever 31 is suppressed, so that the accumulator 9 can be protected.

[0023]

Since the present invention is constructed as described in detail above, a vibration suppressing device for a wheel-type construction vehicle in which vibration during traveling is absorbed by a working machine operating hydraulic circuit provided in the working machine device. The following large effects are achieved. (1) Even if you forget to turn off the vibration suppression device operation switch during work, the vibration suppression circuit is automatically switched to the normal work machine circuit during scooping or boom raising, so there is no danger of boom dropping and safe work. And high pressure is not applied to the pressure switch during operation, so reliability and durability are increased.

(2) At the time of back grading work, maintenance and inspection in a state where the front wheel tires are lifted by a work machine such as front wheel tire replacement, etc., even if the vibration suppression device operation switch is turned on by mistake, it is turned on again from the beginning. Even if there is, the vehicle body can be prevented from falling and safe work can be performed.

(3) When the working lever is provided with a safety lever and a safety switch, the vibration suppressor can be activated or deactivated only by operating the safety lever. Since the movement of the lever is suppressed, the reliability and the durability are increased by protecting the accumulator.

[Brief description of the drawings]

FIG. 1 is an external side view of a wheel loader.

FIG. 2 is a diagram for explaining a conventional electric / hydraulic system.

FIG. 3 is a perspective view showing the vicinity of a working machine operation lever according to the related art.

FIG. 4 is a view for explaining a posture during a back grading operation.

FIG. 5 is a boom for explaining the electric / hydraulic system of the first embodiment.

FIG. 6 is a diagram for explaining an electric / hydraulic system according to a second embodiment.

FIG. 7 is an explanatory diagram illustrating a main part of an electric / hydraulic system according to a third embodiment.

FIG. 8 is a view for explaining a mechanical, electric and hydraulic system of a fourth embodiment.

[Explanation of symbols]

 Reference Signs List 4 boom cylinder 4a head side hydraulic pressure 4b bottom side oil chamber 9 accumulator 11 work machine operation valve 21 vibration suppression device operation switch 22 relay 23 pressure switch 26 electromagnetic switching valve 29 electromagnetic switching valve 30 second accumulator 31 working machine lever 32 safety lever 33 Safety switch

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-244720 (JP, A) JP-A-2-53623 (JP, A) JP-A-2-147727 (JP, A) 47854 (JP, U) Japanese Utility Model Hei 2-70045 (JP, U) Japanese Utility Model Sho 63-165356 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) E02F 9/22

Claims (4)

(57) [Claims] In a vibration suppression device for a wheel type construction vehicle, vibrations during traveling are absorbed by a working machine operating hydraulic circuit provided in the working machine device.
An electromagnetic switching valve 26 having a check valve 26b in an oil passage 25 connecting the bottom side oil chamber 4b and the accumulator 9;
A pressure switch 23, and an oil passage 2 branched from an oil passage 27 connecting the head side oil chamber 4a and the work implement operating valve 11.
8, an electromagnetic switching valve 29 having a check valve 29b, an operation of the pressure switch 23, and a vibration suppression device operation switch 2
1. A vibration suppressing device, comprising: a relay 22 that operates in response to the operation of (1). 2. The pressure switch 23 according to claim 1,
Is provided in an oil passage 27 connecting the head side oil chamber 4a and the work implement operation valve 11. 3. The electromagnetic switching valve 29 according to claim 2,
A second accumulator 30 is provided at the oil discharge port of the vibration suppressor. 4. The pressure switch 23 according to claim 1,
A vibration suppressor characterized by comprising a safety lever 32 for restricting the operation of the work implement lever 31 and a safety switch 33 that is turned on and off by the operation of the lever 32.