JP5528175B2 - Hydraulic circuit of loader working machine and hydraulic control method thereof - Google Patents

Description

  The present invention relates to a hydraulic circuit of a loader working machine such as a front loader and a truck loader, and a hydraulic control method therefor.

2. Description of the Related Art Conventionally, a front loader bucket level control device that performs horizontal control in which a bottom surface of a bucket is in a horizontal state when the boom is lowered while the bucket is scooped and grounded after dumping the bucket of the front loader is known. .
This bucket horizontal control device is provided with a detector for detecting the inclination of the bottom surface of the bucket with respect to the horizontal line, with a solenoid valve for the bucket cylinder connected to the downstream side of the solenoid valve for the boom cylinder, and a signal from this detector. By using this, after starting horizontal control, the bucket bottom is always kept horizontal even when the boom is descending (see Patent Document 1).

Japanese Patent Publication No. 6-102906

However, in the conventional bucket horizontal control device, the entire amount of hydraulic oil supplied to each cylinder is ensured regardless of the boom height and the bucket dump angle, so that the boom and the bucket move at full speed.
Therefore, when the bucket is largely inclined toward the dump side, the boom reaches the lowest position before the boom is lowered and the bottom surface of the bucket becomes a substantially horizontal state at the time of ground contact. There is a risk that the bucket may rush into the ground.

  In view of such a point, the present invention provides a flow dividing means for short-circuiting a part of hydraulic oil that can be supplied to the boom cylinder from the boom control valve to the work implement control valve when the boom is lowered and horizontal grounding control is performed. It is an object of the present invention to provide a hydraulic circuit for a loader working machine that can prevent the working tool from being pushed in when the grounding is performed by slowing down the boom lowering speed while making the working tool crawl at full speed.

  In the present invention, when lowering the boom and performing horizontal grounding control, the time for lowering the boom from the raised position to the lowest position is substantially the same as the time until the work tool is changed from the dumping posture to the bottom grounding posture. Thus, an object of the present invention is to provide a hydraulic control method for a loader working machine that can prevent a work tool tilted forward at the time of ground contact from being pushed into the ground.

In order to solve the above problems, the present invention employs the following technical means.
First, a boom control valve 4 for a boom cylinder 3 that raises and lowers the boom 2 and a work tool cylinder 6 that is connected to the downstream side of the boom control valve 4 and scoops and dumps the work tool 5 at the tip of the boom 2. A parallel control means 8 for raising the boom 2 while maintaining the work tool 5 in a fixed posture with respect to the horizontal line, and the boom control valve 4 and the work tool control valve 7. Horizontal grounding control means 9 for lowering the boom 2 to the lowest position while scooping the work tool 5 dumped at the position to make the bottom surface grounding posture,
The boom control valve 4 transfers a part of the hydraulic oil that can be supplied to the boom cylinder 3 during the operation of the horizontal grounding control means 9 from the bypass line PB1 of the boom control valve 4 to the main line PP2 of the work implement control valve 7. It has the characteristic that it has the diversion means 10 supplied to the working-tool control valve 7 by making it short-circuit and joining the hydraulic oil after operating the said boom cylinder 3.

Secondly, the amount of hydraulic oil that causes the shunting means 10 to short-circuit to the work tool control valve 7 increases as the inclination angle β of the work tool 5 toward the dump side at the start of the operation of the horizontal grounding control means 9 increases. It is characterized in that many are set.
Third, the boom 2 is raised and lowered by the boom control valve 4 via the boom cylinder 3, and the tip of the boom 2 is connected via the work tool cylinder 6 by the work tool control valve 7 connected to the downstream side of the boom control valve 4. The work tool 5 is scooped and dumped, and the boom control valve 4 and the work tool control valve 7 perform parallel control to raise the boom 2 while maintaining the work tool 5 in a fixed posture with respect to the horizontal line, and the lift position A hydraulic control method for a loader working machine that performs horizontal grounding control for lowering the boom 2 to the lowest position while scooping the work tool 5 dumped in step B to a bottom grounding posture,
The inclination angle β of the work tool 5 at the start of the horizontal grounding control is supplied to the work tool control valve 7 after operating the boom cylinder 3 and is lowered to the lowest position of the boom 2. When the scooping operation of the work tool 5 is at an angle that does not reach the bottom contact posture, the boom control valve 4 performs a part of the hydraulic oil that can be supplied to the boom cylinder 3 by the horizontal contact control after the boom cylinder 3 is operated. The time T1 during which the boom 2 is lowered from the raised position to the lowest position by accelerating the scooping operation of the work tool 5 and delaying the lowering of the boom 2 by supplying the working oil to the working tool control valve 7 is provided. The working tool 5 is substantially the same as the time T2 from the dumping posture to the bottom surface grounding posture.

Fourth, the time T1 for lowering the boom 2 from the raised position to the lowest position is lengthened as the inclination angle β of the work tool 5 toward the dump side at the start of the horizontal grounding control is larger. .
The hydraulic circuit of the loader working machine having the above characteristics and the hydraulic control method thereof have the following effects.

  The boom control valve 4 is provided with a flow dividing means 10 for short-circuiting a part of the hydraulic oil that can be supplied to the boom cylinder 3 from the boom control valve 4 to the work implement control valve 7 when the horizontal grounding control means 9 is operated. Is short-circuited from the bypass line PB1 of the boom control valve 4 to the main line PP2 of the work tool control valve 7, and the amount of oil supplied to the boom cylinder 3 is suppressed while securing the total amount of hydraulic oil that can be supplied to the work tool cylinder 6. It is possible to perform the scooping operation of the work tool 5 at full speed and at the same time to lower the lowering speed of the boom 2, so that the boom 2 reaches the lowest position before the work tool 5 assumes the bottom surface contact posture. This prevents the working tool 5 from being pushed in.

  Further, the larger the tilt angle β of the work tool 5 at the start of the operation of the horizontal grounding control means 9, the greater the amount of hydraulic oil to be short-circuited to the work tool control valve 7, thereby the tilt angle β of the work tool 5 is increased. Accordingly, it is possible to adjust the amount of oil supplied to the boom cylinder 3 while securing the total amount of hydraulic oil supplied to the work tool cylinder 6, and the work tool 5 can be adjusted with respect to various inclination angles β of the work tool 5. The lowering speed of the boom 2 can be controlled so as not to thrust.

Furthermore, by making the time T1 to the lowest position of the boom 2 and the time T2 to the bottom surface contact posture of the work tool 5 substantially the same during the horizontal contact control, the work tool 5 is tilted forward (dumped). It is possible to prevent the working tool 5 from being pushed into the ground without being grounded.
And, as the inclination angle β of the work tool 5 at the start of the horizontal grounding control is larger, the descending time T1 to the lowest position of the boom 2 is lengthened, so that the inclination angle β of various sizes can be increased. It is possible to prevent the working tool 5 from being pushed.

According to the hydraulic circuit of the loader working machine according to the present invention, when the boom is lowered and horizontal grounding control is performed, the hydraulic oil that can be supplied to the boom cylinder is partially short-circuited from the boom control valve to the work implement control valve. It is possible to easily control the lowering speed of the boom while securing the whole amount of hydraulic fluid to be supplied to the work tool control valve and continuously performing the scooping operation of the work tool at the same speed.
According to the hydraulic control method for a loader working machine according to the present invention, when the boom is lowered and horizontal grounding control is performed, the lowering time to the lowest position of the boom and the time to reach the bottom grounding posture of the work tool are substantially the same. By doing so, it is possible to prevent the working tool from rushing into the ground.

It is a schematic diagram of the hydraulic circuit of the loader work machine concerning the present invention. It is explanatory drawing of the loader hydraulic control part of a hydraulic circuit. It is sectional drawing of the principal part of a loader hydraulic control part. It is a graph showing the relationship between a work implement angle and a boom angle. It is a side view of a loader work machine.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 5 shows a tractor with a front loader (loader working machine 21) to which the hydraulic circuit 1 according to the present invention is applied. The loader working machine 21 has a front loader 23 attached to the front portion of the tractor 22. Yes.
The tractor 22 includes a vehicle body 24 that is directly connected to an engine, a clutch housing, a transmission case, and the like. The vehicle body 24 is provided with a pair of left and right front wheels 25 and a rear wheel (not shown) so that the vehicle can run. A bonnet 26 that covers the engine and the like is provided at the front of the vehicle body 24.

A cabin (not shown) is mounted on the vehicle body 24 behind the bonnet 26, and a control unit such as a driver's seat, a handle, and an operation lever (not shown) is provided in the cabin.
As shown in FIG. 5, the front loader 23 includes a pair of left and right mounting frames 27, and a pair of left and right booms 2 whose base ends (rear ends) are pivotally supported by the boom support shafts 28. A pair of left and right boom cylinders 3 interposed between the middle part of the boom 2 and the mounting frame 27 and moving the boom 2 up and down, and a bucket support shaft between the front ends (front ends) of the left and right booms 2. (Working tool support shaft) Bucket (working tool) 5 pivotally supported by 29, and interposed between the bucket 5 and the middle portion of the boom 2 and scooping the bucket 5, dumping (scooping operation and dumping operation) And a pair of left and right bucket cylinders (work implement cylinders) 6.

The loader work machine 21 has bucket inclination angle detection means (work implement inclination angle detection means) 30 for detecting an inclination angle β (absolute angle) with respect to the horizontal line (horizontal direction) of the bucket 5.
The bucket inclination angle detection means 30 includes a boom angle sensor 31 that detects a relative swing angle of the boom 2 with respect to the mounting frame 27, and a bucket angle sensor (work implement angle sensor) that detects a relative swing angle of the bucket 5 with respect to the boom 2. ) 32, and the absolute angle β of the bucket 5 is calculated from the swing angle detected by the boom angle sensor 31 and the tilt angle detected by the bucket angle sensor 32.

The boom angle sensor 31 is constituted by a boom spindle 28 and the bucket angle sensor 32 is constituted by a rotary encoder attached to a bucket spindle 29.
The mounting frame 27 is a boom support member provided on the vehicle body 24. The support frame 33 protrudes outward from the vehicle body 24 in the left-right direction, and protrudes upward from the left-right outer end of the support table 33. And a main frame 34 attached to the vehicle body 24, and these are installed on the left and right sides of the vehicle body 24.

The boom 2 has a base end side (rear end side) pivotally connected to the upper portion of the mounting frame 27 around a boom support shaft 28 in the left-right direction so that the boom 2 can be raised and lowered (vertically swung). Yes. The pair of left and right booms 2 are disposed on both the left and right sides of the bonnet 26, and the boom 2 is connected to each other by a boom coupling body 35 having a cylindrical shape or the like.
The boom cylinder 3 is interposed on the left and right sides of the middle part of the lower surface side of the boom 2 and the middle part of the mounting frame 27 in the vertical direction. The boom 2 can swing up and down by the expansion and contraction of the left and right boom cylinders 3.

  Specifically, the boom cylinder 3 is a double-acting hydraulic cylinder. As shown in FIG. 5, when the hydraulic oil flows into the cylinder chamber 3a on the cylinder rod side and the boom cylinder 3 contracts, the boom 2 is lowered. (See the solid line in FIG. 5). On the other hand, when hydraulic oil flows into the cylinder chamber 3b on the side opposite to the cylinder rod (bottom side), the boom cylinder 3 expands, and at this time, the boom 2 rises (see the one-dot chain line in FIG. 5).

The bucket 5 has a rear lower portion pivotally connected to the front end side (front end side) of the boom 2 so as to be swingable about the bucket support shaft 29, and can be tilted back and forth by the expansion and contraction of the bucket cylinder 6 (scooping operation and dumping). Operation is possible).
The bucket cylinder 6 is interposed on the left and right sides of the middle portion of the upper surface side of the boom 2 and the rear upper portion of the bucket 5. The bucket 5 can be scooped and dumped by the expansion and contraction of the left and right bucket cylinders 6.

Here, the bucket cylinder 6 is also a double-acting hydraulic cylinder like the boom cylinder 3, and as shown in FIG. 5, the hydraulic oil flows into the cylinder chamber 6a on the cylinder rod side, and the bucket cylinder 6 contracts. Sometimes the boom 2 is scooped (that is, tilted backward) (see the two-dot chain line in FIG. 5).
Further, when the hydraulic oil flows into the bottom cylinder chamber 6b, the bucket cylinder 6 expands, and at this time, the bucket 5 dumps (tilts forward) (see the one-dot chain line in FIG. 5).

FIG. 1 shows a hydraulic circuit 1 of a loader working machine for operating a boom 2 and a bucket 5. The hydraulic circuit 1 includes a loader hydraulic control unit 41 for a front loader 23, a boom spool 44 described later, And a controller 43 that adjusts the switching position of the bucket spool 47.
The loader hydraulic control unit 41 controls the boom cylinder 3 and the bucket cylinder 6 in accordance with the operation of an operation lever (not shown). The open center type boom control valve 4 for the boom cylinder 3 and the boom control valve 4 is provided with an open center type bucket control valve (work implement control valve) 7 for the bucket cylinder 6 connected to the downstream side of 4 and electromagnetic proportional pressure reducing valves 51 to 54 (see FIG. 1).

  The loader hydraulic control unit 41 includes a first pump 45 for driving the boom 2, the bucket 5, and the like, and a second pilot pump 46, and a pilot operation supplied from the second pump 46. After the oil is adjusted to an appropriate oil amount by the electromagnetic proportional pressure reducing valves 51 to 54, the direction and amount of hydraulic oil flowing through the boom control valve 4 and the bucket control valve 7 are controlled.

  The boom control valve 4 can be switched to a lowered position 4a, a neutral position 4b, and a raised position 4c by sliding the boom spool 44. The slide amount of the boom spool 44 is controlled by the controller 43 by an electromagnetic proportional pressure reducing valve 51, 52 is controlled and can be adjusted to an arbitrary position. When the boom spool 44 is switched to the neutral position 4b, the hydraulic oil from the port P is supplied to the bucket control valve 7 side as it is through the bypass line PB1.

  When the boom spool 44 is switched to the lowered position 4a, the hydraulic oil passes through the main line PP1 having a check valve and is supplied to the rod side cylinder chamber 3a of the boom cylinder 3 via the port A1. The rod retracts. The return oil flowing out from the bottom side cylinder chamber 3b when the rod is retracted is supplied to the bucket control valve 7 side through the port B1.

Conversely, when the boom spool 44 is in the raised position 4c, the hydraulic oil passes through the main line PP1 and is supplied to the bottom cylinder chamber 3b of the boom cylinder 3, and the rod of the boom cylinder 3 extends. . The return oil at that time is supplied to the bucket control valve 7 side after leaving the rod side cylinder chamber 3a.
Similarly to the boom control valve 4, the bucket control valve 7 can be switched to the dump position 7a, the neutral position 7b, and the scooping position 7c by sliding the bucket spool (work implement spool) 47. The sliding amount of the bucket spool 47 In addition, the controller 43 controls the electromagnetic proportional pressure reducing valves 53 and 54 so that the controller 43 can be adjusted to an arbitrary position. When the bucket spool 47 is in the neutral position 7b, the hydraulic oil from the boom control valve 4 flows directly to the port PB via the bypass line PB2.

When the bucket spool 47 is at the dump position 7a, the hydraulic oil passes through the main line PP2 having a check valve, and a pressure difference is generated in the bucket cylinder 6 due to a difference in piston contact area. It flows into the bottom side cylinder chamber 6b from the chamber 6a through the ports B2 and A2.
On the other hand, when the bucket spool 47 is in the scooping position 7c, the hydraulic oil passes through the main line PP2 and is supplied to the rod side cylinder chamber 6a of the bucket cylinder 6 through the port B2.

The controller 43 shown in FIGS. 1 and 2 controls the slide amounts of the boom spool 44 and the bucket spool 47 of the loader hydraulic control unit 41 based on output signals from the boom angle sensor 31 and the bucket angle sensor 32. And is constituted by a microcomputer or the like.
That is, the controller 43 controls the hydraulic oil (cylinder chamber and oil amount flowing in and out) supplied to the boom cylinder 3 and the bucket cylinder 6, and makes the bucket 5 have a fixed attitude (absolute angle β with respect to the horizontal line). The parallel control for raising the boom 2 while maintaining the predetermined value), and the boom 2 while operating the scooping operation to bring the bucket 5 dumped at the raised position into the bottom surface grounding posture (the bottom surface of the grounded bucket 5 is substantially horizontal). And horizontal grounding control that lowers to the lowest position.

When performing parallel control, if the boom 2 is raised without operating the attitude of the bucket 5, the bucket 5 naturally tilts backward. Therefore, in order to keep the absolute angle β of the bucket 5 constant, a loader The boom spool 44 of the hydraulic control unit 41 is set to the raised position 4c, and the bucket spool 47 is set to the dump position 7a.
At this time, the controller 43 adjusts the sliding amount of the bucket spool 47 in accordance with the boom angle α of the boom 2 (the output signal of the boom angle sensor 31), and operates an appropriate amount in the bottom cylinder chamber 6b of the bucket cylinder 6. Supply oil.

The hydraulic oil amount is adjusted by changing the sliding amount of the bucket spool 47 so that a part of the hydraulic oil leaks from a notch (groove) formed in the thick shaft portion of the dump position 7a of the bucket spool 47. The amount of oil flowing into the 6 side can be adjusted.
As described above, the controller 43 supplies an appropriate amount of hydraulic oil to the bucket cylinder 6 so as to maintain the absolute angle β of the bucket 5 detected by the bucket inclination angle detection means 30 to be constant, thereby realizing parallel control. .

The parallel control means 8 includes the controller 43, the raising position 4c of the boom control valve 4, the dump position 7a of the bucket control valve 7, the bucket inclination angle detecting means 30, and the like.
As shown in FIG. 4, the horizontal grounding control described above is performed when the bucket 5 is moved from the start position S (the bucket 5 is in the dumping posture and the boom 2 is raised) to the goal position G (the boom 2 is lowered). This is because the operation is performed up to the position where the bucket 5 is in the bottom contact posture.

At this time, if the boom 2 is lowered without the operation of the bucket, the bucket 5 further tilts forward, and thus the scooping operation must be performed so that the bucket 5 assumes the bottom surface contact posture.
Therefore, during horizontal grounding control, the boom spool 44 of the loader hydraulic control unit 41 is set to the lowered position 4a (or an intermediate position 4M described later) and the bucket spool 47 is set to the scooping position 7c (see FIG. 1).

  The dotted line in the symbols of the enlarged view of FIG. 1 indicates the amount of slide of the controller 43 when the boom spool 44 is at the lowered position 4a (the boom spool 44 is at an intermediate position 4M between the lowered position 4a and the neutral position 4b). This shows that a part of the hydraulic oil from the port P leaks from the bypass line PB1 and can flow into the main line PP2 of the bucket control valve 7 without passing through the boom cylinder 3.

  Similarly, during the horizontal grounding control, the controller 43 adjusts the hydraulic oil leaking from the notch by sliding the bucket spool 47, and the amount of oil supplied to the rod side cylinder chamber 6a of the bucket cylinder 6 (the scooping operation of the bucket 5). I have control. That is, the controller 43, the lowering position 4a of the boom control valve 4, the scooping position 7c of the bucket control valve 7, the bucket inclination angle detecting means 30, and the like constitute the horizontal grounding control means 9.

Here, as described above, the controller 43 can also control the slide amount of the boom spool 44 and can simultaneously control the amount of oil supplied to the boom cylinder 3.
The boom spool 44 is a notch for allowing a part of hydraulic oil to flow to the port A1 at a portion (a thick shaft portion indicated by X in FIGS. 2 and 3) that communicates the main line PP1 and the port A1 of the boom control valve 4. Part of hydraulic oil from the bypass line PB1 at a portion (a thick shaft portion indicated by Y in FIGS. 2 and 3) that connects 4X and the main line PP2 that is an oil passage to the bypass line PB1 and the bucket control valve 7 Are formed in the notch 4 </ b> Y for allowing the valve to flow directly to the bucket control valve 7.

A notch 4X in the thick shaft portion indicated by X is a groove formed along the axial direction of the boom spool 44, and overlaps the main line PP1 in the axial direction when the boom spool 44 is at the intermediate position 4M. It is the groove length.
Therefore, as shown by the arrow N1 in FIG. 3, at the intermediate position 4M of the boom spool 44, the hydraulic oil flows into the port A1 from the main line PP1 through the notch 4X. It is suppressed more than when it is in the position 4a.

Similarly to the notch 4X, the thick shaft notch 4Y indicated by Y is a groove along the axial direction, and the groove length overlaps the bypass line PB1 in the axial direction at the intermediate position 4M of the boom spool 44. Is formed.
Therefore, as shown by the arrow N2 in FIG. 3, when the boom spool 44 is at the intermediate position 4M, the hydraulic oil passes from the bypass line PB1 to the main line PP2 (and bypass line PB2) of the bucket control valve 7 through the notch 4Y. Inflow.

  Such inflow did not occur when the boom spool 44 was at the lowered position 4a, but when the boom spool 44 was at the intermediate position 4M, part of the hydraulic oil from the bypass line PB1 leaked, Without being supplied to the boom cylinder 3, it is short-circuited to the main line PP2 of the bucket control valve 7 as it is, and joins the hydraulic oil (indicated by arrow N3 in FIG. 3) after the boom cylinder 3 is operated.

By this merging, the hydraulic oil supplied to the bucket control valve 7 can secure the entire amount, while suppressing the hydraulic oil supplied to the boom cylinder 3. The control of the lowering speed of 2 can be easily realized.
That is, during the horizontal grounding control, the lowering speed of the boom 2 can be slowed while the scooping operation of the bucket 5 is performed at full speed.

Further, the controller 43 is configured to calculate the absolute angle β of the bucket 5 from the angle data of the input angle sensors 31 and 32, and the larger the absolute angle β, the shorter the bucket control valve 7. The slide amount of the boom spool 44 is set to be adjustable so that the amount of hydraulic oil to be increased is increased.
The notch 4X, 4Y, the controller 43, the boom spool 44, the bucket inclination angle detecting means 30 and the like constitute the flow dividing means 10.

A usage mode of the hydraulic circuit 1 of the loader working machine, that is, a hydraulic control method of the loader working machine will be described.
When the loader working machine 21 performs a dumping operation in which the boom 2 is lifted and the earth and sand are loaded onto a truck or the like while keeping the opening edge of the bucket 5 into which the earth and sand are scraped substantially horizontal, the earth and sand should not be spilled from the bucket 5. The parallel control means 8 performs parallel control for raising the boom 2 while maintaining the bucket 5 in a fixed posture with respect to the horizontal line.

  After dumping the earth and sand, in order for the loader working machine 21 to scrape the earth and sand into the bucket 5 again, the dumped bucket 5 whose boom angle α is a predetermined value and whose absolute angle β is a predetermined value is removed. The horizontal grounding control means 9 performs horizontal grounding control for lowering the boom 2 to the lowest position (that is, the boom angle α becomes 0) while performing a scooping operation to make the bottom surface grounding posture.

At this time, the controller 43 calculates the absolute angle β of the bucket 5 at the start of the horizontal grounding control, and adjusts the slide amount of the boom spool 44 at the intermediate position 4M corresponding to the absolute angle β.
A part of the amount of hydraulic oil corresponding to the amount of sliding is not supplied to the boom cylinder 3 by the flow dividing means 10, but a part of the hydraulic oil leaks from the bypass line PB1 and short-circuits to the main line PP2 of the bucket control valve 7 as it is. Therefore, it is possible to suppress the hydraulic oil supplied to the boom cylinder 3 while securing the total amount of hydraulic oil supplied to the bucket control valve 7.

At this time, the sliding amount of the boom spool 44 is such that the time T1 required to lower the boom 2 from the raised position of the boom angle α to the lowest position (the boom angle α becomes 0) is the dumping posture of the bucket 5. It is determined to be substantially the same as the time T2 required from the (posture inclined to the dump side by the absolute angle β) to the bottom contact posture.
When the boom 2 and the bucket 5 are moved from the start position S to the goal position G in FIG. 4, the boom 2 is lowered by the angle α within the same time, but the bucket 5 is only the angle (α + β). It means that it works ugly.

As a result, during horizontal grounding control, the lowering speed of the boom 2 can be slowed while performing the scooping operation of the bucket 5 at full speed, and the boom 2 reaches the lowest position before the bucket 5 assumes the bottom surface grounding posture. , And the thrust of the bucket 5 into the ground can be eliminated.
Furthermore, the controller 43 increases the time T2 until the bottom surface is brought into contact with the bottom surface as the absolute angle β at the start of the horizontal contact control increases, so that the lowering time T1 to the lowest position of the boom 2 is increased. The slide amount of the boom spool 44 is set.

Therefore, it is possible to prevent the bucket 5 from being pushed into the absolute angle β of various sizes.
In addition, this invention is not limited to embodiment mentioned above. Each configuration of the hydraulic circuit 1 or the like of the loader working machine or the overall structure, shape, dimensions, and the like can be appropriately changed in accordance with the spirit of the present invention.
The work tool 5 does not have to be a bucket for carrying earth and sand or ore, and may be a fork, a handler, a grader, or the like.

  The loader hydraulic control unit 41 lowers the boom 2 while maintaining the work tool 5 in a constant posture with respect to the horizontal line as well as the parallel control for raising the boom 2 while maintaining the work tool 5 in a constant posture with respect to the horizontal line. It is also possible to perform control.

DESCRIPTION OF SYMBOLS 1 Hydraulic circuit of loader work machine 2 Boom 3 Boom cylinder 4 Boom control valve 5 Work implement (bucket)
6 Work tool cylinder (bucket cylinder)
7 Work tool control valve (bucket control valve)
8 Parallel control means 9 Horizontal grounding control means 10 Diverging means 21 Loader working machine β Absolute angle of work tool T1 Time for lowering boom from raised position to lowest position T2 Time until working tool is brought from dumping position to bottom grounding position

Claims (4)

A boom control valve (4) for a boom cylinder (3) for raising and lowering the boom (2), and a work tool (5) at the tip of the boom (2) connected to the downstream side of the boom control valve (4) A work tool control valve (7) for the work tool cylinder (6) to be dumped, and the work tool (5) with respect to a horizontal line to the boom control valve (4) and the work tool control valve (7). The parallel control means (8) that raises the boom (2) while maintaining a constant posture, and the boom (2) is moved to the lowest position while the working tool (5) dumped at the raised position is operated to make a bottom grounding posture. Horizontal grounding control means (9) for lowering to
The boom control valve (4) supplies a part of hydraulic oil that can be supplied to the boom cylinder (3) when the horizontal grounding control means (9) is operated from the bypass line (PB1) of the boom control valve (4). A shunting means (10) for supplying to the work tool control valve (7) by short-circuiting to the main line (PP2) of the work tool control valve (7) and joining the hydraulic oil after operating the boom cylinder (3). A hydraulic circuit of the loader working machine.   The diversion means (10) is short-circuited to the work tool control valve (7) as the inclination angle (β) of the work tool (5) to the dump side at the start of the operation of the horizontal ground control means (9) increases. 2. The hydraulic circuit for a loader working machine according to claim 1, wherein a large amount of hydraulic oil is set. The boom control valve (4) raises and lowers the boom (2) through the boom cylinder (3), and the work tool control valve (7) connected to the downstream side of the boom control valve (4) 6) The work tool (5) at the tip of the boom (2) is scooped and dumped via 6), and the work tool (5) is moved with respect to the horizontal line by the boom control valve (4) and the work tool control valve (7). Parallel control is performed to raise the boom (2) while maintaining a constant posture, and the boom (2) is lowered to the lowest position while the work tool (5) dumped at the raised position is operated to make a bottom contact posture. A hydraulic control method for a loader working machine that performs horizontal grounding control,
The inclination angle (β) of the work tool (5) at the start of the horizontal grounding control supplies the working oil after operating the boom cylinder (3) to the work tool control valve (7), and the boom (2 ) When the scooping motion of the work tool (5) is at an angle that does not reach the bottom grounding posture while descending to the lowest position, the boom control valve (4) can supply the boom cylinder (3) by horizontal grounding control. A part of the working oil is joined to the working oil after the boom cylinder (3) is actuated and supplied to the work tool control valve (7) to accelerate the scooping operation of the work tool (5) and the boom (2 ) Is slowed down, the time (T1) for lowering the boom (2) from the raised position to the lowest position, and the time (T2) until the work tool (5) is changed from the dumping posture to the bottom surface grounding posture. The hydraulic control method for the loader working machine, characterized in that it is substantially the same.   The time (T1) for lowering the boom (2) from the raised position to the lowest position is increased as the inclination angle (β) of the work tool (5) to the dump side at the start of the horizontal grounding control is larger. The hydraulic control method for a loader working machine according to claim 3.

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