JPS6059236A - Front loader floating automatic shutoff device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of troubles caused by maloperations by providing a detector for raising positions of a working tool on the tip of a boom, a detector for excess burden to the working tool above a given burden, and a shutter valve to close a floating circuit during the detecting period of both said detectors. CONSTITUTION:When a control valve 10 is out of floating, a detector 21 is operated to release a shutter valve 17, and by switching control valves 10 and 12, a boom cylinder 4 and a bucket cylinder 6 are allowed to extend or contract freely. When soil is fully loaded on the bucket 5 and the cylinder 4 is extened, a load detector 18 is operated by discharge pressure of the oil-pressure pump 9 if the burden of the bucket 5 exceeds a given one. When the bucket 5 goes up to a given height, a position detector 20 is operated, a valve drive circuit 19 is actuated, and the shutter valve 17 is excited to interrupt between the control valve 10 and the cylinder 4. The falling down of the bucket 5 by maloperations can thus be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a floating automatic shut-off device for a front loader, and the present invention relates to a floating automatic shut-off device for a front loader. This is to prevent the floating circuit from falling suddenly.

In a front loader equipped with a complete set of working tools, such as a packet, at the tip of the boom, the control valve for raising and lowering the boom is provided with a floating function, so that uniform armor work can be performed in a floating state.

However, since this type of control valve can be operated arbitrarily at any time, for example, when the boom is being raised high to transport a packet full of soil and sand, the control valve may be accidentally switched to the floating state. Otherwise, there was a risk that the packet would suddenly fall unexpectedly and cause an accident.

The present invention was provided for the purpose of solving these nine problems in the conventional art.The present invention is characterized by the fact that the control valve for raising and lowering the boom has a floating function. The control device teζ includes a position detector that detects that the working tool at the tip of the boom is in the raised position, a load detector that detects that the weight capacity of the working tool (TII+ is higher than a predetermined value), and a The main point is equipped with a shutoff valve that shuts off the floating circuit when detected.

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.
The figure shows a packet type front loader for tractor equipment, in which (1) is a tractor, (2) is a mounting frame, and (3) is a pair of left and right booms, which are pivoted on the mounting frame (2) so that they can be raised and lowered. It can be raised and lowered by a pair of left and right boom cylinders (4). (5) is a packet, which is pivoted at the tip of the boom (3), and has a pair of left and right packet cylinders +61
VC,! Rotation operation is possible. (7) is a three-point linkage mechanism, and (8) is a hydraulic system for raising and lowering a CVc-threatened working machine through a three-point linkage mechanism (7). 9) is a hydraulic pump that is driven by the engine. (10) is the boom cylinder (4
) fljlJ m valve, in addition to being able to switch the operating lever (11) to the neutral, up, and down positions, it also has a floating part (10a)'e, and when operated to this floating part (10a), , boom cylinder (4
) so that both cylinder chambers communicate with each other. u7J
are control valves of the packet cylinder (6), which can be operated by a control lever 0 fathom, and these control valves LIOI n are connected in series between the hydraulic pump (9) and the hydraulic device (8).

Incidentally, the hydraulic system (8) is of course connected to a dedicated control valve. En α5) Hachinic valve, α61H relief valve. t17) is an electromagnetic shutoff valve, and the control valve (10
) and the boom cylinder (4) so as to interrupt the floating circuit. (+81nm heavy detector, pressure switch and hydraulic pump (
9) and the control valve (lO), and detects that a direct weight of more than a predetermined value is acting on the packet (6) by a change in the pressure on the discharge side of the hydraulic pump (9).

FIG. 3 shows a control circuit for a cutoff valve 071, which is driven by a valve drive circuit α91. The 5F drive circuit α has a position detector 4 that detects the rise of the packet (5), and the aforementioned load detector (I and detector 12+ that detects states other than floating of the control valve (lO)). When the respective signals are input and the detector 0 → cut-off is operated, the cut-off valve η is excited and cut off, and when the detector 12+1 is operated, the cut-off valve ! 17) is configured to demagnetize and release the magnet. The position detector (sha) is attached to the pivot portion of the boom (3) and is configured to detect the rise of the packet (5) through the vertical movement of the boom (3).

In the above configuration, when the control valve (+i) is at a position other than 70-ting, the detector I that is linked to this control valve (lO)
21) is operated and the shutoff valve η is in the released state. Therefore, by switching the control valve (+01 tl), the boom cylinder (4) and the packet cylinder (6) can freely expand and contract, allowing normal work to be carried out and also allowing use in a floating state.

If the boom cylinder (4) is extended after filling the packet (6) with soil, etc., the
If the direct weight of J is equal to or higher than a predetermined value, the load detector H operates 11 times depending on the discharge pressure of the hydraulic pump (9). When the kerat (6) rises to a certain height, the boom (3) rises to a certain height.
) through which the position detector nod operates. For this reason, the valve drive circuit (1st cycle) is activated, and the area between the shutoff valves is excited and shuts off between the control valve (ltl and the boom cylinder (4), so the control valve (
10) Floating part (10a') due to incorrect operation
Even if it appears on the side, the floating circuit will remain disconnected. Therefore, it is possible to prevent the boom (4) from descending and the kerato (5) to suddenly fall, improving safety, and without requiring special care during operation. Good properties. Moreover, in the middle of falling, there was a drop (
If the tractor 6) is abruptly stopped, excessive stress will be applied to the vehicle body, front axle, etc. of the tractor 11+, but this problem can be prevented.

The working tool may be a fork or the like other than the packet 5). The raised position does not necessarily have to be the upper limit of the working tool, and can be set at an intermediate position for safety reasons.

In the present invention, when the work tool is raised to the raised position with a direct load of more than 'Pft constant, the shutoff valve
The V-shaped structure prevents the work tool from falling suddenly due to incorrect operation of the control valve, improving safety and improving safety.
Improves operability.

4 to 8 disclose a control device other than the one according to the present invention, and FIG. 4 shows a solenoid valve type hydraulic circuit, in which a solenoid valve for controlling the xzt6 boom cylinder (4), 5
) Solenoid valve for controlling Hapaquet cylinder (6),
These are connected in series with the solenoid valve 2z at the front stage and the solenoid valve 23) at the rear stage. The solenoid valve 2z has a solenoid for raising (241) and a solenoid for lowering 4, and a solenoid valve 231
has a dump solenoid and a rollback solenoid. ``2&'' is a pressure detector, which is connected to the hydraulic circuit between the solenoid valve 2 and the hydraulic pump (9). The pressure detector generates an output at time t when the circuit pressure rises to a cracking pressure that is slightly lower than the relief pressure of the relief valve OQ. @ is an operation detector for the hydraulic system (8), which is composed of a pressure switch. Note that this operation detector 29) may be constituted by a limit switch that is linked to a hydraulic control lever that controls the hydraulic system (8).

Figure 5 shows the control circuit, f30) is the operation switch for raising the boom, +3++ is the operation switch for lowering the boom, (321 is the operation switch for packet dumping, and time is the operation switch for packet rollback. For example, it is possible to selectively operate one operation lever for the shite boom and the packet respectively.
(3G) ~ NANDAND circuit) is an RSS flip-flop circuit consisting of a NAND circuit, "f401 Il
1 is a NOT circuit, 4 (4 barrels) (5 (capital) is an AND circuit.

In the configuration shown in Figures 4 and 5, earth and sand excavation and loading work is carried out using a boom cylinder (
4) and the packet cylinder (6) can be expanded and contracted.

During such work, the control circuit operates as follows and drives each of the solenoid valves 2 and 1 in accordance with signals. For example, when rolling back a packet (5), if you operate the operation switch ``V'', a packet rollback signal is generated, which is passed through an AND circuit (4) to a transistor (
When solenoid 5 is activated, the solenoid (271) of the solenoid valve (271) is energized, and the solenoid valve (271) is activated in the rollback direction.

Therefore, the packet cylinder (6) contracts and the packet (6)
) rolls back.

When dumping a packet (5), the operation switch 3 generates a packet dump signal, and the AND circuit @η, the transistor (the solenoid □□□ of the solenoid valve is energized via the 5 switch, and the solenoid valve causes the dump). The packet cylinder (6) expands and the packet (5) is dumped.

When raising or lowering the boom (3), press the operation switch (3).
0) or 01) generates a boom up signal or a boom down signal, and the solenoid (23) of the solenoid (
24) or 4 is energized, the solenoid valve 1221 operates in the upward or downward direction, the boom cylinder (4) extends or contracts, and the boom (3) rises or falls.

When operating the operation switches (■) and (G) at the same time to raise the boom (3) while rolling back the packet t5+k, each solenoid valve 22123+ operates as described above, and the boom cylinder (4) Pressure oil is supplied from the hydraulic pump (9) and pressure oil from the boom cylinder (4) is supplied to the packet cylinder (6), respectively, and each cylinder t41+61 is operated. In addition, each cylinder 14++6
1 has the same diameter and the same volume. At this time,
If the circuit pressure detected by pressure detector 8 is below cracking 1, no pressure detection signal is generated, so NAND
Since the AND circuit output is at the iJH level, the output of the flip-flop circuit [39] is set to the previous state, that is, the L level, to 1.
In a daze, NOT circuit α1), AND circuit (4 (to) (state) operates through AND circuit f441. Of course, AN
The output of the D circuit is also at the ■ level. When an overload is applied for some reason and the circuit pressure reaches cracking pressure, the pressure detector operates and generates a pressure detection signal, so all the human power in the NAND circuit becomes H level, and its output becomes Change to L level. Therefore, the output of the flip-flop circuit A9) becomes H level, and the NOT circuit (A9) becomes H level.
41), the AND circuit (c) (441) is closed, so each solenoid valve 2z row returns to neutral, and the cylinder +4116
1 both expanded and contracted, interrupting the 3 works. In other words, the work is suspended, and this state is maintained even if the circuit pressure falls below the cracking pressure. Therefore, when either one of the irons (operation switch 噸) is returned, the output of the AND circuit (531) becomes L.
Since the level changes, the output of the flip-flop circuit (39) becomes L level, and the output from the solenoid valve (411, AND circuit i, 4th floor H1, AND circuit (9),
123), only one of them is operational and the other is inoperable. That is, once the circuit pressure rises to the cracking pressure, unless one of the signals is cut off, the solenoid valve 2
2123+ maintains a neutral state, and only when some number n is selected can the suspension be canceled and the transition to the next n1 operation possible. Therefore, even though the solenoid valves 2z and 231 are connected in series, large back pressure such as cracking pressure does not act on the preceding solenoid valve Z21.On the other hand, when the front loader t is working, hydraulic pressure Device (8)
If the front loader side is used, there is a fear that the pressure on the oil pressure i fft 18+ side will act as back pressure on the solenoid valve β row, and the front loader side will not operate and fall. Solenoid valve, 221
, the DI seal may be damaged.

However, at this time, the operation detector 29) indicates that the hydraulic system +81
The operation of the signal i is inverted in the NOT circuit, and the level signal enters the AND circuit (4'A"f: and then the flip-flop circuit (39) VC, so the solenoid valve β1 is connected as described above. It is possible to return to the neutral state, thereby preventing the occurrence of problems due to the effect of back pressure, and improving safety.These operations are shown in the flow diagram of FIG.

When operating the solenoid valve 2zi231 with one operating lever (I), if the operating direction is cross-shaped as shown in Fig. and a light emitting element for command display (50~(5
9) Throw the light emitting elements (631) for operation confirmation on the outside, command from the operating lever 15 (1) and the solenoid valve! 21,
By making the operation (23) visible on the display of the light emitting element, safe and efficient work can be performed. Note that a pressure display light emitting element (6 (a)) and a packet position display light emitting element (6υ) may be provided on the display board (5 (f)).

When operating the solenoid valve 221.23+ with two levers, it is sufficient to set rjt''L corresponding to each lever as shown in FIG.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the present invention, in which FIG. 1 is a side view, FIG. 2 is a hydraulic circuit diagram, and FIG. 3 is a block diagram. The figures show a control system different from the present invention, Fig. 4 is a hydraulic circuit, Fig. 5 is an electric circuit diagram, Fig. 6 is a flow chart, and Figs. 7 and 8 are diagrams showing display boards. . il+...Tractor, (3)...Boom, (4)・
・・Boom cylinder, (5)・・Packet, (6)・
...packet cylinder, tlol[121...flI
l[l valve, (10a)...floating part, η
...Shutoff valve, 0~...Load detector, Short...Position detector.

Claims (1)

[Claims] 1. In a front loader control device in which the control valve for raising and lowering the boom has a floating function, there is a position detector that detects that the work tool at the tip of the boom is in the raised position, and a position detector that detects that the work tool at the tip of the boom is at a predetermined position. A floating automatic cut-off device for a front loader, characterized in that it is equipped with a load detector that detects the above, and a cut-off valve that cuts off a floating circuit when these detectors detect the above.