JP2556697B2 - Hydraulic device for dumper control of loader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is mounted on a power vehicle for agricultural tractors, and is applied to various works such as scooping, carrying, dumping earth and sand, compost, grass and the like. More specifically, a loader configured so that a tip attachment such as a bucket mounted on the tip of a lift arm is configured to perform a dumping operation by extending and contracting a plurality of dump cylinders arranged in a lateral direction. The present invention relates to a hydraulic device for dump control.

(Prior Art) FIG. 8 is a side view showing a configuration of a loader mounted on an agricultural tractor. In the figure, 1 is a tractor body, 2
Is a loader mounting frame that is detachable from the tractor body 1,
Reference numeral 3 is a lift arm pivotally connected to the mounting frame 2 so as to be vertically swingable, and is configured to be vertically movable via a pair of left and right lift cylinders 4A and 4B. Reference numeral 5 denotes a tip end attachment such as a bucket, which is pivotally connected to the tip end portion of the lift arm 3 via a quadruple link 6 so as to be swingable, that is, damping. 7A and 7B are dump cylinders, which are arranged in a pair of left and right at an upper position near the tip of the lift arm 3, and the tips of their piston rods 7Aa and 7Bb are pivotally connected to a four-link.

FIG. 9 is a conventional hydraulic system diagram of a dump control hydraulic device of a loader having the above-described configuration. In the figure, reference numeral 8 is an up / down switching valve interposed in a hydraulic path to the pair of lift cylinders 4A, 4B, and has three ports, an ascending port 8a, a descending port 8b, and a neutral port 8n. Reference numeral 9 is an expansion / contraction switching valve for the pair of dump cylinders 7A and 7B, which is an extension port.
9a, contraction port 9b, and neutral port 9n.
In the figure, 15 is a tank and 16 is a pump.

10 is the switching valve 9 and a pair of dump cylinders 7
A speed control valve interposed between A and 7B,
Hydraulic pressure is supplied to the full-bore side 7a, 7b side of both dump cylinders 7A, 7B at the same time, and the operating speed can be switched in two stages while releasing the hydraulic pressure from the annulus 7a ', 7b' side simultaneously. It has two ports 10a, 10b. That is, on one port 10b side, the return oil passage is bypass-connected to the oil supply passages to the cylinders 7A, 7B, and when switching to this port 10b side, the return oil is bypassed to the oil supply passage, The operating speed of the dump cylinders 7A and 7B can be made higher than that when the other port 10a is used.

(Problems to be Solved by the Invention) In the conventional dump control hydraulic device for the loader configured as described above, the dump operation speed can be switched between two stages by switching the speed control valve. However, even when switching to the high speed side, the amount of oil corresponding to the annulus volume of both dump cylinders is required, so there was a limit to the increase in dump speed.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a hydraulic device for dumper control of a loader capable of doubling the dump speed as compared with the conventional one by a simple configuration improvement.

(Means for Solving the Problems) In order to achieve this object, a dump control hydraulic device of a loader according to the present invention includes a plurality of expansion / contraction switching valves interposed in hydraulic system passages of a plurality of dump cylinders. At the time of dumping operation, at least one dump cylinder is independent of other dump cylinders, and a speed increasing valve capable of switching to a free operating state is interposed in a hydraulic system path between the dump cylinder and the other dump cylinder. It is characterized by

(Operation) According to the present invention, at least 1
To operate one dump cylinder independently of the other dump cylinder, operate the speed increasing valve as needed to switch the independent dump cylinder to a free operating state, thereby enabling dump operation. It becomes possible to reduce the total amount of oil required by the amount of oil required to operate the independent dump cylinder. As a result, the operating speed of the other drive-side dump cylinders increases, and when a pair of left and right dump cylinders is used, the dump speed can be increased to about double.

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

In each of the embodiments, the configuration of the loader itself is the same as that shown in FIG.
The case where A and 7B are used will be described. Further, the same reference numerals as those in the hydraulic system diagram shown in FIG. 9 are given, and detailed description thereof will be omitted.

Embodiment 1 In the hydraulic system diagram shown in FIG. 1, reference numeral 11 denotes a speed increasing valve, which is interposed in a hydraulic system path between the speed adjusting valve 10 and the one-side dump cylinder 7A. This speed increasing valve 11 has a normal port 11a and a port 11b forming a bypass circuit between the full bore 7A side and the annulus 7a 'side of the dump cylinder 7A itself. When switching to the extension port 9a side, an operation switching signal from the sensor switch 12 automatically switches to the port 11b side, and in parallel with this, the speed control valve 10 also automatically switches to the port 10b side. Is configured.

13 is a vacuum prevention valve, which is an acceleration valve
It is interposed in parallel to 11. When the pair of dump cylinders 7A and 7B are extended at a high speed, the vacuum prevention valve 13 is automatically opened in association with an increase in hydraulic pressure in the supply system passage, and the full bore 7a side of the dump cylinder 7A is closed. It serves to prevent the inside of the full bore 7a from becoming a vacuum by sending oil to.

 Next, the operation of the above configuration will be described.

As shown in FIG. 2, the expansion / contraction valve 9 is attached to the extension port 9a side,
That is, when the dump switch is operated to the dump operation position and the sensor switch 12 is turned on, the speed increasing valve 10 is switched to the port 10b side and the speed increasing valve 11 is switched to the port 11b side.

As a result, in the one dump cylinder 7A, the full bore 7a side and the annulus 7a ′ side of the dump cylinder 7A are detoured through the port 11b to be in a free operating state, and the total amount of oil by the pump 16 is reduced. It will be sent to the full bore 7b side of the other dump cylinder 7B. At this time, since both dump cylinders 7A and 7B are in the extension direction, the operating load thereof is very small, and the operating force of the other dump cylinder 7B can sufficiently oppose. As a result, the pair of dump cylinders 7A and 7B can be extended at a very high speed and can perform an efficient dumping action.

Second Embodiment The hydraulic system diagram of this embodiment shown in FIG. 3 is exactly the same as that of the first embodiment. The difference from the first embodiment is that the sensor switch 12 is operated by switching only the speed control valve 10. Switch 12a, speed control valve 10 and speed increasing valve 11
Both of them are separately provided with a switch 12b for switching operation at the same time.

According to the second embodiment, the normal speed dump with both the switches 12a and 12b turned off, the medium speed dump with only one switch 12a turned on, the high speed dump with both switches 12a and 12b turned on, and the like. The dump speed can be selected in three stages, which has the advantage of being even easier to use.

Embodiment 3 In the hydraulic system diagram of the embodiment shown in FIG.
The difference is that the speed control valve 10 and the speed increasing valve 11
The point is that a variable speed valve 14 that integrates the and is used.This valve 14 has a normal speed port 14a and a high speed port 14b.
It is a 2-port type.

According to the third embodiment, the number of valves for changing the speed is 1
In addition, since the valve operating electric system can be unified, it has an advantage that the whole structure is simple and inexpensive.

Embodiment 4 In the hydraulic system diagram of the embodiment shown in FIG. 5, the difference from Embodiment 3 is that the annulus 7a 'side of the dump cylinder 7A is
The point is that the variable speed valve 14 is connected to the tank 15 through the inside of the variable speed valve 14 in the switching state to the high speed side.

According to the fourth embodiment, since the oil on the annulus 7a 'side of the one dump cylinder 7A in the free state at the time of high speed dump is returned directly to the tank 15, as in each of the first to third embodiments, the annulus 7a' is used. The pressure loss inside the pipe is smaller than in the case where the side and the full bore 7a side are connected to form a bypass circuit.
It has an advantage that the dump speed can be further increased.

Embodiment 5 In the hydraulic system diagram of this embodiment shown in FIG. 6, the difference from Embodiment 1 is that the speed control valve 10 is omitted and only the speed increasing valve 11 is interposed. It is in.

Sixth Embodiment The sixth embodiment shown in FIG. 7 functions and operates in the same manner as the first, second or fifth embodiment, except that the arrangement of the speed increasing valve 11 is changed.

In each of the above-described embodiments, the case where a pair of left and right dump cylinders is used has been described, but three or more dump cylinders are used, and one or two of them are independent of other dump cylinders. It is also possible to make it possible to switch to a free operating state.

(Effects) As described above, according to the present invention, at least one of the plurality of dump cylinders is made independent of the other during the dump operation, and is switched to the free operation state, so that a constant pump capacity is maintained. It is possible to increase the amount of oil sent to the drive side cylinder per unit time to increase the dump speed about twice as compared with the conventional one.

Therefore, a simple modification such as replacement or addition of the valve has the effect of significantly improving the dump work efficiency.

In particular, if you add a speed increasing device to one that is already equipped, you can make a further high speed dump,
Dump speed can also be controlled in stages, which has the effect of contributing to the expansion of the loader work range.

It should be noted that it is not limited to the implementation of only the dump control described above, and it is also possible to increase the lift arm lifting speed when there is no load
It can also be applied to forklifts.

[Brief description of drawings]

1 and 2 are hydraulic system diagrams showing an embodiment of a hydraulic device for dumper control of a loader according to the present invention. 3 to 7 are hydraulic system diagrams showing another embodiment, FIG. 8 is a side view showing the configuration of the loader, and FIG. 9 is a conventional hydraulic system diagram. 3 ...... Lift arm 5 ...... Tip attachment 7A, 7B ...... Dump cylinder 7Aa, 7Bb ...... Piston rod 7a, 7b ...... Full bore 7a ', 7b' ...... Annulus 9 ...... Expansion / conversion switching valve 11 ...... Accelerate Valve

Claims (3)

(57) [Claims] 1. A hydraulic system path for a plurality of dump cylinders, wherein tip ends of piston rods of a plurality of laterally arranged dump cylinders are pivotally connected to an upper portion of a tip attachment attached to a tip portion of a lift arm. In addition to supplying hydraulic pressure to the full bore side of these dump cylinders at the same time, the extension operating state that releases the hydraulic pressure from the annulus side simultaneously, and the contracting operating state that supplies the hydraulic pressure to the annulus side simultaneously and releases the hydraulic pressure from the full bore side at the same time. In a dumper control hydraulic device of a loader having a valve that can be switched between and, a hydraulic system path between the expansion and contraction switching valve and a plurality of dump cylinders has a plurality of dump cylinders At least one of them is independent of other dump cylinders, and a speed-up valve that can be switched to a free operating state A hydraulic device for dumper control of a loader characterized by being interposed. 2. The speed increasing valve forms a bypass circuit between the annulus side and the full bore side of at least one dump cylinder itself independent of other dump cylinders. A hydraulic device for dumper control of the loader according to the first aspect. 3. The dumper for a loader according to claim 1, wherein the speed increasing valve directly connects the annulus side of at least one dump cylinder independent of the other dump cylinders to the tank. Control hydraulic system.