JPS63843Y2 - - Google Patents

Description

[Detailed explanation of the invention] Industrial application field This invention relates to an agricultural front loader, and its purpose is to increase the dumping speed of an advanced working machine such as a bucket cart attached to the end of the front loader's lift arm. The purpose is to improve work efficiency by speeding up the work, and to improve separation of adhesive work objects when discharging them.

BACKGROUND ART This type of agricultural front loader is equipped with a front loader B at the front of a tractor A, as shown in FIG.

A lift arm 1, which constitutes the main part of the front loader B, has its base pivoted to a part of the frame of the tractor A so as to be movable up and down, and is raised and lowered by a lift cylinder 2. Various types of tip working devices 3 are replaceably attached to the tip of the lift arm 1 (the drawing shows a bucket), and this tip working device 3 is
It is rotated by the dump cylinder 4 directly or via a link 5 and a rod 6 as shown so as to enable forward dumping or rearward rake.

Problems to be solved by the invention When working with such an agricultural front loader, the workpiece, such as agricultural products, is
The scooping speed is not as much of an issue as on the left, but
It is desired that the speed at which the workpiece scooped up by the tip working device 3 is discharged to a transport vehicle or the like is rapid to improve work efficiency.

In response to the above request, conventional techniques include increasing the size of the hydraulic pump and piping, using a vacuum prevention valve to quickly discharge the load due to its own weight, or using a differential circuit for the directional control valve. However, it has been unsatisfactory due to drawbacks such as cost, operability, and increased back pressure due to piping and valves.

Means for Solving the Problems This invention consists of a lift cylinder that moves up and down a lift arm whose base end is pivotally connected to a tractor, and a tip working mechanism that is pivotally connected to the tip of the lift arm that moves a piston rod to protrude and extend. In an agricultural front loader equipped with a single-rod type double-acting dump cylinder that performs a dumping operation by a retracting operation and a rake operation by a retracting and retracting operation, an oil passage on the side of the piston front chamber connected to the piston front chamber of the dump cylinder, and an oil passage connected to the piston front chamber of the dump cylinder. A first non-return check inserted between an oil passage on the piston rear chamber side connected to the piston rear chamber and an oil passage on the piston front chamber side, which prevents return oil from the piston front chamber and enables supply. a throttle connected in parallel to the first check valve in the middle of the oil passage on the piston front chamber side; and a throttle connected in the middle of the oil passage on the piston front chamber side at a position closer to the piston front chamber than the throttle; One end is connected in the middle, and the other end is branched and connected to the oil passage on the side of the rear chamber of the piston, and is always held in the closed position by a spring, and the hydraulic pressure of the oil passage on the side of the rear chamber of the piston is used as pilot oil pressure to open the speed increaser. The valve is inserted in the middle of the oil passage connecting the speed increasing valve to the oil passage on the piston front chamber side, and prevents oil from passing from the piston rear chamber side, and prevents oil from passing from the piston front chamber side. A second check valve is provided to allow the return oil to pass through.

Function First, in the retracting and retracting operation of the dump cylinder, the oil passage on the front chamber side of the piston of the dump cylinder is connected to the hydraulic pump, and the oil passage on the side of the rear chamber of the piston is connected to the tank. This causes oil from the hydraulic pump to open the first check valve and flow into the piston front chamber, and oil in the piston rear chamber to return to the tank. At this time, the speed increase valve remains closed,
The dump cylinder piston rod moves in and out at normal speed.

Next, when the oil passage on the piston rear chamber side of the dump cylinder is connected to the hydraulic pump, and the oil passage on the piston front chamber side is connected to the tank, the following two operating speeds are obtained.

First, when the amount of oil supplied from the hydraulic pump is large, the oil passage on the side of the front chamber of the piston is prevented from returning to the tank by the first check valve, so it communicates with the tank through the throttle, and the flow rate is small. Then just return to the tank. Therefore, the oil pressure in the oil passage on the piston rear chamber side increases, the speed increasing valve is opened, and most of the return oil on the piston front chamber side is merged and supplied to the oil passage on the piston rear chamber side. Here, the hydraulic pressure between the front and rear chambers of the piston is almost equal, but the pressure-receiving area of the piston differs depending on whether or not there is a rod, and there is pressure leakage from the throttle, which causes the piston rod to protrude and expand. The operating force in the direction of the piston is greater, and most of the return oil in the front chamber of the piston joins the rear chamber of the piston, so the dump cylinder has a flow rate of oil sent from the hydraulic pump and the flow rate of return oil from the front chamber of the piston. As a result, the flow rate per unit time increases, and the protrusion and extension speed of the piston rod increases in proportion to this increase in flow rate, so that a speed-up dump operation is performed. At this time, since the second check valve is present, the oil in the oil passage on the piston rear chamber side does not flow to the piston front chamber through the speed increasing valve.

Next, when the amount of oil supplied to the hydraulic pump is small, the oil passage on the piston front chamber side communicates with the tank through the throttle, and because the amount of oil supplied to the piston rear chamber is small, the piston rear chamber side The oil pressure in the oil passage does not become high enough to open the speed increasing valve, but instead causes the piston rod to protrude and extend at low speed.

Embodiment Figure 2 schematically shows the overall hydraulic circuit when the present invention is applied to an agricultural front loader.
In FIG. 2, 4 is a dump cylinder, and the lift cylinder is omitted. 7 is a directional control valve for the dump cylinder 4, and 8 is a directional control valve for the lift cylinder, which controls the direction of the hydraulic oil of the hydraulic pump 9 and the return oil to the tank 10, so as to provide each cylinder with the desired operation. It is something that allows people to do this.

The speed increasing valve C, which is the main point of this invention, is
As shown by the dashed line block in FIG. 2, it is installed as close to the dump cylinder 4 as possible.

The specific configuration of the speed increasing valve C is shown in FIG. 3, which will be described later.

First, the mode of operation of the hydraulic circuit will be explained with reference to FIG.

The two directional control valves 7 and 8 both have three switching positions, and the state shown in FIG.
At the neutral position, the hydraulic oil of the hydraulic pump 9 is returned to the tank 10 through the reserve ports of both valves 7 and 8, resulting in no-load operation.

In this state, if only one valve is switched to the operating position, the cylinder connected to the main port of the valve will be expanded or contracted in the corresponding direction, and both valves 7 and 8 will be operated at the same time. In this case, the return oil of the cylinder controlled by one valve causes the cylinder controlled by the other valve to follow suit, and in the circuit example shown in FIG. 2, the return oil of the lift cylinder is transferred to the dump cylinder 4. This shows the case where it is sent to the machine and operated.

In addition, in FIG. 2, 11 is a main relief valve provided in the middle of the supply path of hydraulic oil from the hydraulic pump 9.

FIG. 3 is a hydraulic circuit diagram illustrating the specific structure of the speed increasing valve used in the present invention. In this case, the first check valve 19 is connected to the oil passage 12 connected to the piston front chamber of the dump cylinder 4. A throttle 20 is connected in parallel with these, and a speed increasing valve C connected in parallel with these is inserted and connected to a branch oil passage of the oil passage 13 in the piston rear chamber of the dump cylinder 4 via a second check valve 21. , this speed increasing valve C is always made to block both oil passages 12 and 13 with a spring 22,
In addition, pilot oil passages 23 and 24 are provided facing each other from the oil passage 12 and the oil passage 13 immediately after the throttle 20. The configurations 19 to 24 in Figure 3 above are 1
It is constructed as a unit within one valve structure.

In this example, the dump cylinder 4 is contracted, ie, scooped, at a normal speed without the speed increase valve C operating.

On the other hand, the extension operation of the dump cylinder 4 is as follows.

That is, since the oil passage 12 always communicates with the tank through the throttle 20, when the flow rate of the hydraulic pump is large, the return oil from the piston front chamber side cannot freely return to the tank due to the flow rate limiting action of the throttle 20, and the oil is not returned to the tank at the rear of the piston. The oil pressure in the chamber increases, and the speed increasing valve C opens.
Most of the return oil on the piston front chamber side is merged and supplied to the piston rear chamber side, resulting in a speed-up dump, and when there is less oil, the pilot oil path 2 of the speed-up valve C is
4 does not become high, the speed increasing valve C does not open, and the oil in the piston front chamber returns to the tank through the throttle 20, allowing it to be dumped at a slow speed.

The flow rate control of the hydraulic pump can be performed, for example, by controlling the opening and closing of a throttle of the engine.

To explain the above-mentioned operation during speed-up dumping in more detail with reference to FIG. 3, the hydraulic pressure from the pump acts on the rear chamber of the piston of the cylinder 4 through the oil passage 13, and at the same time acts on the piston rear chamber of the cylinder 4 from the pilot oil passage 24 to oppose the spring 22. This acts in the direction of opening the speed increasing valve C. At this time, if the oil pressure from the pump becomes higher than the set pressure of the spring 22, the speed increasing valve C is opened. In this manner, when the speed increasing valve C is opened, the piston front chamber and the piston rear chamber of the cylinder 4 communicate with each other via the speed increasing valve C. When the front and rear chambers of the piston communicate with each other in this manner, hydraulic pressure from the pump acts on the front and rear surfaces of the piston of the cylinder 4. At this time, the propulsive force of the piston is expressed as (difference in pressure receiving area) x (hydraulic pressure from the pump).

Since the piston is a single rod type, the difference in pressure receiving area corresponds to the cross-sectional area of the piston rod.

When the piston starts moving forward with the above-mentioned propulsive force, the hydraulic fluid in the piston front chamber is forced out and has no choice but to flow into the piston rear chamber through the speed increasing valve C. That is, since the hydraulic pressure acting on the front and rear sides of the piston remains the same and only the piston moves forward, the hydraulic oil in the piston front chamber flows into the piston rear chamber. At this time, the flow rate of the hydraulic oil flowing from the piston front chamber to the piston rear chamber is Q/sec, and the flow rate of the hydraulic oil sent out from the pump is
Assuming Q'/sec, (Q+Q') hydraulic oil will be sent to the piston rear chamber. Then, the moving speed of the piston is expressed as the above (Q + Q') divided by the cross-sectional area S of the piston, so the speed is increased by Q/S compared to the case where the piston is moved only by pressure oil from the pump. I am forced to do it.

Effects of the invention According to this invention, the amount of oil supplied to the hydraulic pump can be
It is possible to perform high-speed dumping and low-speed dumping by adjusting the opening/closing control of the engine throttle, and it is possible to improve the unloading of sticky work objects (earth and sand, compost, livestock feed, etc.). .

In particular, with this idea, there is no need to make the hydraulic pump or piping large, and it is only necessary to connect and insert a simple one-piece speed increase valve between the oil passages in the front and rear chambers of the dump cylinder, so it can be implemented at low cost. There are features that can be used.

[Brief explanation of the drawing]

Fig. 1 is a schematic side view of the agricultural front loader that is the subject of the present invention, Fig. 2 is a schematic diagram of the entire hydraulic circuit thereof, and Fig. 3 illustrates the specific structure of the speed increasing valve used in the present invention. It is a hydraulic circuit. 1... Lift arm, 2... Lift cylinder,
3... Tip working machine, 4... Dump cylinder, C...
... Speed-up valve.

Claims (1)

[Claims for Utility Model Registration] A lift cylinder that moves up and down a lift arm whose base end is pivotally connected to a tractor, and a tip working device that is pivotally connected to the tip of the lift arm that performs a dump operation by the protrusion and extension operation of a piston rod. , an agricultural front loader equipped with a single-rod double-acting dump cylinder that performs a scooping motion by retracting and retracting, an oil passage on the piston front chamber side connected to the piston front chamber of the dump cylinder, and an oil passage connected to the piston rear chamber of the dump cylinder. a first check valve that is inserted in the middle of the connected oil passage on the piston rear chamber side and the oil passage on the piston front chamber side to prevent return oil from the piston front chamber and enable supply; a throttle connected in parallel with the first check valve to the middle of the oil passage on the piston front chamber side; and one end connected in the middle of the oil passage on the piston front chamber side at a position closer to the piston front chamber than the throttle. a speed increasing valve which is connected to the piston rear chamber side, and whose other end is branch-connected to the oil passage on the piston rear chamber side, is always held in a closed position by a spring, and is operated to open using the hydraulic pressure of the piston rear chamber side oil passage as pilot hydraulic pressure; The speed increase valve is inserted in the middle of the oil passage connecting to the piston front chamber side oil passage, and prevents oil from passing from the piston rear chamber side oil passage, and prevents oil from returning from the piston front chamber side oil passage. An agricultural front loader characterized by comprising a second check valve that allows passage.