JP2686106B2 - Shovel loader boom and bucket controller - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boom and bucket control device for a shovel loader, and more particularly, to self-leveling for automatically holding a bucket in a horizontal position when the boom is moved up and down. The present invention relates to a boom and bucket control device having a valve.

(Prior Art) In a conventional shovel loader, the most common automatic leveling device that automatically tilts the bucket so that it keeps the horizontal posture when the boom is raised and lowered is a mechanical type that uses a parallel link mechanism. Linkage devices are known. Since this linkage device has a problem that the lifting mechanism part becomes large or increased, as a solution to the problem, a hydraulic automatic leveling device, specifically, an automatic leveling device using a self-leveling valve. Have been proposed, and the method is disclosed in, for example, U.S. Pat.
It is disclosed in the specification and drawings. FIG. 4 is a circuit diagram of the hydraulic automatic leveling device disclosed in this U.S. Pat.

This is a directional control valve 51 for lift cylinders, a directional control valve 52 for dump cylinders and other directional control valves for attachments.
A self-leveling valve 56 including a shunt valve 55 with a servo is installed downstream of a control valve 54 including three directional control valves 53 and 53 in the form of a series circuit. The first position a, which functions to divert the discharge oil from the rod-side oil chamber when the cylinder 57 rises, and the total amount of the hydraulic oil from the lift cylinder directional control valve 51, when the cylinder 57 descends, are set to the rod-side oil chamber of the lift cylinder 57. It is adapted to be switched by the servo means to the second position b which functions to bypass.

That is, when the lift cylinder direction switching valve 51 is switched to the rising side, a part of the oil discharged from the rod-side oil chamber of the lift cylinder 57 passes through the first position “a” of the diversion valve 55 and then the dump cylinder 58. While sending to the bottom oil chamber, the remaining oil is returned to the tank 59 via the lift cylinder directional control valve 51 to tilt the bucket in the forward tilt direction according to the lift amount and keep the bucket horizontal. Further, when the lift cylinder directional control valve 51 is switched to the lower side, it is supplied to the rod-side oil chamber of the lift cylinder 57 via the second position b of the flow dividing valve 55.

(Problems to be Solved by the Invention) By the way, during the loading and unloading work by the shovel loader, the boom and the bucket are often operated not only independently but also at the same time. At times, operations such as quickly discharging the soil of the bucket by tilting the bucket forward while continuing to move upward while the boom is rising are frequently performed. Further, such simultaneous operation is extremely important in achieving high efficiency of loading work.

However, in the conventional shovel loader equipped with the self-leveling valve 56, when the boom raising operation and the bucket forward tilting operation are performed simultaneously, the hydraulic oil delivered from the rod-side oil chamber of the lift cylinder 57 is transferred to the head of the dump cylinder 58. Since the oil is supplied to the side oil chamber, the operating speed of the dump cylinder 58 becomes slower by an amount corresponding to the rod diameter of the lift cylinder 57 than when the bucket is independently tilted forward.
That is, when the hydraulic oil sent from the rod-side oil chamber of the lift cylinder 57 is supplied to the dump cylinder 58,
The amount of hydraulic oil supplied from the hydraulic pump to the dump cylinder 58 is higher than that of the lift cylinder 57 as compared with the case where the hydraulic oil is directly supplied to the dump cylinder 58 via the directional switching valve 52 for the dump cylinder.
There is a problem that the dump speed is slowed down by the amount corresponding to the rod diameter of, and dirt from the bucket is poor. Such poor soil separation caused by the slow dumping speed does not bring out the effect of the simultaneous operation, but rather causes a decrease in work efficiency.

In view of the above problems, it is an object of the present invention to make the forward tilting speed of the bucket during the simultaneous operation equal to that during the single operation.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides self-leveling on the downstream side of a control valve including a directional switching valve for a lift cylinder and a directional switching valve for a dump cylinder in the form of a series circuit. A valve is provided, and the hydraulic oil sent from the lift cylinder when the boom is raised or lowered is split into a regulated flow rate and a surplus flow rate at a predetermined ratio by the flow dividing valve of the self-leveling valve, and the adjusted split oil is sent to the dump cylinder. A boom and bucket control device for a shovel loader of a type capable of automatically leveling a bucket by means of the control valve, wherein the directional switching valve for the dump cylinder in the control valve is provided upstream of the directional switching valve for the lift cylinder. When operating these two-way switching valves at the same time, hydraulic oil is supplied to the dump cylinder prior to It is characterized in that the spilled oil from the Linda is supplied to the lift cylinder.

(Operation) If the switching operation of the lift cylinder directional control valve to the raised position and the operation of switching the dump cylinder directional control valve to the forward tilt position are performed at the same time, the hydraulic oil from the hydraulic pump is transferred to the bottom chamber of the dump cylinder. The hydraulic oil that has been sent and accordingly sent out from the rod-side oil chamber is supplied from the dump cylinder direction switching valve through the lift cylinder direction switching valve to the bottom oil chamber of the lift cylinder. That is, the supply of hydraulic oil to the dump cylinder precedes the lift cylinder, and the supplied oil amount is equivalent to that when the dump cylinder directional control valve is operated independently. Therefore, even if the bucket operated by the dump cylinder is operated simultaneously, the bucket can be tilted forward at the same speed as in a single operation, which is faster than the conventional case.

(Example) Hereinafter, an example of the present invention will be specifically described with reference to the drawings. FIG. 2 shows an outline of the shovel loader, and the boom 3 whose base end is supported by the pillar 2 of the vehicle main body 1 so as to be vertically rotatable is configured to be lifted and lowered by a lift cylinder 4. The bucket 5 attached to the tip of the is tilted forward and backward by the dump cylinder 6.

FIG. 1 shows an embodiment of the control device of the present invention. The hydraulic fluid pumped up and discharged from the tank 8 by the hydraulic pump 7 is used as a directional switching valve 9 for a dump cylinder, a directional switching valve 10 for a lift cylinder, and an earth auger used for digging work, for example. The flow direction is controlled by a cargo control valve 12 which includes a direct switching valve 11 for attachment as a series circuit. Therefore, the order of arrangement of the directional control valves in the control valve 12 is set so that at least the directional control valve 9 for the dump cylinder is on the upstream side of the directional control valve 10 for the lift cylinder. From downstream to downstream, they are arranged in the order of dump cylinder, lift cylinder, and attachment.

On the other hand, the directional control valve 9 for the dump cylinder is an open center type three-position type, has a forward tilt position c, a neutral position b, and a rear tilt position a, and is connected to the dump cylinder 6 by the pipe lines 13 and 14. Connected, and the directional control valve 10 for the lift cylinder is an open center type 4-position type
Ascending position a, neutral position b, descending position c, float position d
And the pipes 15 and 16 are connected to the lift cylinder 4.

Further, the control valve 12 and the lift cylinder 4 and the dump cylinder 6 which are the actuators on the downstream side thereof.
A self-leveling valve 17 for automatically adjusting the level of the bucket 5 is incorporated in the circuit connecting the and. In this embodiment, it is carried out both when the boom is raised and when the boom is lowered. For boom raising, the diversion valve 18 and the two switching valves 19, 20 are provided in the rod side circuit of the lift cylinder 4. The relief valve 21 and the check valve 22 are included, and the diversion valve 30 and the two switching valves 31, 3 are provided in the bottom side circuit of the lift cylinder 4 for lowering the boom.
2, the relief valve 33, and the check valve 34 are included.

A specific description will be given of the rod-side circuit that is executed when the boom is raised. The flow dividing valve 18 has its inlet connected to the rod-side oil chamber of the lift cylinder 4 and its adjustment outlet connected to a pipe 13 communicating with the bottom-side oil chamber of the dump cylinder 6 via a pipe 23. The surplus outlet is incorporated so as to communicate with the direction switching valve 10 for the lift cylinder.
The check valve 22 is inserted into the conduit 23, and the relief valve 21 keeps the set pressure. Further, the flow dividing valve 18 has a structure that can be switched to a position where the conduit 23 on the adjusting outlet side is closed by the pressure on the excessive outlet side acting through the pilot line 24.

Then, the inlet side and the surplus outlet side of the flow dividing valve 18 are connected by a bypass pipe 25, and the one switching valve 19 is inserted in the bypass pipe 25. In this way the shunt valve
The switching valve 19 inserted in parallel with the
Opening and closing are controlled by the rod side oil chamber pressure of the dump cylinder 6 acting on the open side through the pilot line 27 and the bottom side oil chamber pressure of the lift cylinder 4 acting on the pilot line 27, and both pressures act together. When or when they do not work together, a spring holds them in the open position. Also, the other one switching valve 20 is
It is built in a pipe line 28 that connects the pipe line 14 that connects the rod-side oil chamber of the dump cylinder 6 and the directional switching valve 9 for the dump cylinder, and the pipe line 28 that connects the surplus outlet side of the flow dividing valve 18, and is always It is held in the closed position, and can be switched to the open position by the pressure on the adjusted outflow side of the flow dividing valve 18 acting via the pilot line 29.

Next, the bottom side circuit implemented for boom lowering will be described. Basically, it is the same as that for the above-described ascending operation, and the flow dividing valve 30 has its inlet port in the lift cylinder 4
Of the check valve 34
Is connected to the rod-side oil chamber of the dump cylinder 6 via the pipes 28 and 14 from which the pipe is inserted, and the surplus outlet is connected to the lift cylinder directional control valve 10. The relief valve 33 for keeping the pressure in the pipe 35 at a predetermined pressure is provided in the pipe 36 connecting the pipe 35 and the suction pipe 7a of the hydraulic pump 7. Further, the flow dividing valve 30 has a structure capable of switching to a position where the conduit 35 on the adjusting outlet side is closed by the pressure on the excessive outlet side acting via the pilot line 37.

Then, the inlet side and the surplus outlet side of the flow dividing valve 30 are connected by a bypass pipe 38, and the one switching valve 31 is inserted in the bypass pipe 38. In this way the shunt valve
The switching valve 31 inserted in parallel with 30 is the pilot line 39
Opening and closing are controlled by the bottom side oil chamber pressure of the dump cylinder 6 acting on the opening side via the pilot line 40 and the rod side oil chamber pressure of the lift cylinder 4 acting on the closing side via the pilot line 40. It is adapted to be held in the open position by a spring when working together or not working together. Also, another one switching valve
32 is a shunt valve in the rod side circuit of the lift cylinder 4.
It is incorporated in the pipeline 41 that connects the pipeline 23 leading to the adjustment outlet of 18 and the pipeline 15 leading to the surplus outlet of the flow dividing valve 30 in the bottom side circuit, and is always held in the closed position and piloted. It is switched to the open position by the pressure on the adjusting outlet side of the flow dividing valve 30 acting via the line 42.

The present embodiment is configured as described above, and its operation will be described below.

(When the boom is raised) When the lift cylinder directional control valve 10 is switched to the raised position a, the hydraulic oil discharged from the hydraulic pump 7 reaches the switching valve 31 of the bottom side circuit of the self-leveling valve 17 through the pipe line 15. Since the switching valve 31 is held at the open position by the spring, the hydraulic oil is sent to the bottom side oil chamber of the lift cylinder 4 via the bypass pipe 38, and the boom 3
Rises. At this time, the pressure of the bottom side oil chamber acts on the switching valve 19 in the rod side circuit via the pilot line 27 to switch the switching valve 19 to the closed position, so that the operation sent from the rod side oil chamber of the lift cylinder 4 is performed. Oil diversion valve
Step 18 is entered and the bucket 5 is divided at a preset ratio so as to keep the angle of the bucket 5 constant.

Then, the split oil on the adjustment outflow side is sent from the pipe line 23 to the bottom side oil chamber of the dump cylinder 6 via the pipe line 13, and the bucket 5 is tilted forward. That is, the bucket 5 is automatically adjusted so as to maintain the horizontal posture in response to the rise of the boom 3. At this time, since the pressure in the conduit 23 on the adjusting outlet side of the flow dividing valve 18 acts on the switching valve 20 via the pilot line 29 to switch the switching valve 20 to the open position, the rod side of the dump cylinder 6 is closed. The discharged oil sent from the oil chamber merges with the excess oil from the excess outlet of the flow dividing valve 18 via the pipes 14 and 28, and returns to the tank 8 via the pipe 16 and the lift cylinder direction switching valve 10.

When the dump cylinder 6 becomes overspeed due to the weight of the bucket 5 while the boom 3 is being raised, if the bottom side oil chamber of the dump cylinder 6 is about to cause a negative pressure state, the lift cylinder 4 The pressure in the rod-side oil chamber of No. 2 drops to zero, the pressure drop causes the pressure in the pilot line 29 to disappear, and the switching valve 20 is switched to the closed position by the spring to shut off the flow in the pipeline 28. Of oil from the rod side oil chamber is blocked. Therefore, the operation of the dump cylinder 6 is temporarily stopped until the pressure in the oil chamber on the bottom side of the dump cylinder 6 is sufficiently increased, and when the pressure is increased, the original operation is resumed.

If the dump cylinder 6 reaches the stroke end while the lift cylinder 4 is being lifted, the flow dividing valve
The split oil from the adjustment outlet side of 18 returns to the tank 8 through the relief valve 21 as the oil flow in the pipes 23 and 16 is blocked.

(During boom lowering) When the lift cylinder directional control valve 10 is switched to the lowered position c, the hydraulic fluid discharged from the hydraulic pump 7 reaches the rod side circuit switching valve 19 of the self-leveling valve 17 via the pipe line 16. At this time, the switching valve 19 is held in the open position by the spring, so that the working oil flows through the bypass line 25.
After that, the boom 3 is sent to the rod-side oil chamber of the lift cylinder 4, and the boom 3 is lowered. At this time, the pressure in the rod side oil chamber acts on the switching valve 31 in the bottom side circuit via the pilot line 40 to switch the switching valve 31 to the closed position, so that the operation sent out from the bottom side oil chamber of the lift cylinder 4 is performed. The oil enters the flow dividing valve 30 from the pipe line 15 and is divided at a predetermined ratio in the same manner as when rising. Then, the split oil on the adjustment outlet side is supplied from the pipe 35 through the check valve 34 and the pipes 28, 14 to the rod-side oil chamber of the dump cylinder 6, and the bucket 5 is tilted rearward. That is, the bucket 5 descends and is automatically leveled according to the descending amount.

Further, at this time, the pressure on the adjustment outlet side of the flow dividing valve 30 acts on the switching valve 32 via the pilot line 42 and switches it to the open position, so that the oil sent from the bottom side oil chamber of the dump cylinder 6 is piped. It joins with the surplus oil of the flow dividing valve 30 via the passages 13, 23, 41, and returns to the tank 8 via the pipe passage 15 and the lift cylinder direction switching valve 10.

That is, according to the present embodiment, the bucket 5 can be automatically leveled both when the boom 3 is raised and when it is lowered, and the boom 3 at that time is adjusted.
The hydraulic oil from the hydraulic pump 7 is used to raise and lower the
Since it can be supplied to the lift cylinder 4 through the bypass line 28 or 38 without passing through, it is possible to raise and lower at the same high speed as in the case without the self-leveling valve 17.

(When the bucket is tilted forward or backward) When the dump cylinder directional control valve 9 is switched to the forward tilt position c, the hydraulic oil from the hydraulic pump 7 passes through the pipe line 13 to the bottom side oil chamber of the dump cylinder 6. While being supplied, the working oil sent from the rod-side oil chamber is returned to the tank 8 via the pipe line 14 and the dump cylinder directional control valve 9, so that the bucket 5 is tilted forward. Further, when the dump cylinder direction switching valve 9 is switched to the rearwardly inclined position a, the flow of the hydraulic oil is opposite to that described above, and the bucket 5 is rearwardly inclined. That is,
When the directional control valve 9 for the dump cylinder is operated independently, the dump cylinder 6 is operated without using the self-leveling valve 17.

(When the boom is raised and the bucket is tilted forward) When the dump cylinder directional control valve 9 is switched to the forward tilt position c and the lift cylinder directional control valve 10 is switched to the raised position a, the hydraulic oil from the hydraulic pump 7 is discharged. It is supplied to the bottom side oil chamber of the dump cylinder 6 from the direction switching valve 9 via the pipe 13, and the bucket 5 is tilted forward. Then, the hydraulic oil sent from the rod side oil chamber of the dump cylinder 6 is sent to the dump cylinder directional switching valve 9 via the pipe line 14, and from this, the lift cylinder switching valve 10
Through the line 15 and the self-leveling valve 17 through the same route as in the above-mentioned single operation.
Is sent to the bottom side oil chamber, and the boom 3 rises. At this time, the switching valve 19 of the bypass line 25 in the rod side circuit acts in a direction in which the pressures of the rod side oil chamber of the dump cylinder 6 and the bottom side oil chamber of the lift cylinder 4 are opposite to each other via both pilot lines 26 and 27. However, since both the pressures are balanced with each other, the switching valve 19 is eventually held in the open position by the biasing force of the spring, so that the hydraulic oil sent from the rod-side oil chamber of the lift cylinder 4 is bypassed. From the pipe 25, the pipe 16 and the lift cylinder directional control valve 10 are returned to the tank 8.

(When the boom is lowered and the bucket is tilted backward) When the dump cylinder directional control valve 9 is switched to the rearward tilted position a and the lift cylinder directional control valve 10 is switched to the lowered position c, the hydraulic oil from the hydraulic pump 7 is discharged. It is supplied to the rod side oil chamber of the dump cylinder 6 from the direction switching valve 9 through the pipe line 14, and the bucket 5 is tilted backward. Then, the hydraulic oil sent from the bottom side oil chamber of the dump cylinder 6 is sent to the dump cylinder directional switching valve 9 via the pipe line 13, and from this, the lift cylinder switching valve 10
Through the line 16 and the self-leveling valve 17 through the same route as in the above-described single operation.
Is sent to the rod side oil chamber, and the boom 3 descends. At this time, the switching valve 31 of the bypass line 38 in the bottom side circuit acts in a direction in which the pressures of the bottom side oil chamber of the dump cylinder 6 and the rod side oil chamber of the lift cylinder 4 are opposite to each other via the pilot lines 39, 40. However, since both the pressures balance each other, the switching valve 31 is eventually held in the open position by the urging force of the spring, so that the hydraulic oil sent from the bottom side oil chamber of the lift cylinder 4 is bypass pipe. Line 38 to pipe 15 and lift cylinder directional control valve
Return to tank 8 via 10.

Therefore, in this embodiment, the boom 3 as described above is used.
During the simultaneous operation of raising and lowering the bucket and tilting the bucket 5 forward and backward, the working oil can be supplied to the dump cylinder 6 prior to the lift cylinder 4, so that the operating speed thereof is the same as that of the single operation described above. That is, during the simultaneous operation, the bucket 5 can be dumped at the same speed as that during the single operation.

Therefore, when loading the soil on the truck T as shown in FIGS. 5 to 9, it is possible to effectively remove the soil from the bucket 5.

That is, the shovel loader scoops up the earth and sand (Fig. 5), and when it approaches the truck T to some extent, it further approaches while raising the boom 3 (Fig. 6) until the bucket 5 comes to the bed of the truck T. Move forward (Fig. 7),
The vehicle is stopped, the bucket 5 is tilted forward while raising the boom 3, and the earth and sand of the bucket 5 are placed on the bed of the truck T (FIG. 8). At this time, the forward tilting speed of the bucket 5 is the same as that during the single operation of the bucket, so that soil removal is good.
Then, the vehicle moves backward as it is, and when the bucket 5 is disengaged from the bed of the truck T, the boom 5 is lowered and the bucket 5 is tilted backward to complete the work (FIG. 9).

FIG. 3 shows a modification of the self-leveling valve 17. That is, in the modification shown in the figure, the self-leveling valve 17 is configured so that the dump cylinder 6 operates to automatically level the bucket 5 only when the boom is raised, and is incorporated only in the rod side circuit of the lift cylinder 4. Has been. Since the specific configuration is the same as that of the above-described embodiment, the same reference numerals as those shown in FIG. 1 are given and the description thereof is omitted. Although not shown in the figure, conversely, the self-leveling valve 17 is incorporated only in the bottom side circuit of the lift cylinder 4 so that the dump cylinder 6 operates so as to automatically level the bucket 5 only when the boom is lowered. Is also possible.

(Effects of the Invention) As described in detail above, according to the present invention, in the boom and bucket control device of the shovel loader equipped with the self-leveling valve in the hydraulic circuit for the automatic horizontal leveling of the bucket, the boom raising and lowering and the front and rear of the bucket. The bucket can be dumped at the same speed as when it is tilted at the same time as when it is independently operated. It is possible to effectively remove the soil from the bucket when loading,
It is very useful for improving work efficiency.

By the way, when it is attempted to determine the amount of movement of the boom so that the bucket is horizontal when the boom is raised or lowered, the cylinder diameter and rod diameter of the lift cylinder and the dump cylinder, which are related to the movement of the boom and the bucket, or There is a constraint that the design must be made in consideration of the distance from the working point of the lift cylinder to the rotation fulcrum of the boom and the distance from the working point of the dump cylinder to the rotation fulcrum of the bucket. However, as in the present invention, when the hydraulic oil that flows out from the lift cylinder and is sent to the dump cylinder is adjusted by the flow dividing valve of the self-leveling valve, there is no restriction on the setting as described above. A great degree of freedom in design can be obtained.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of a boom and bucket control device of the present invention, FIG. 2 is a schematic side view of a shovel loader, and FIG. 3 is a hydraulic circuit diagram showing a modification of a self-leveling valve. FIG. 5 is a hydraulic circuit diagram showing a conventional example, and FIGS. 5 to 9 are explanatory diagrams showing a work of loading soil on a truck. 3 …… Boom 4 …… Lift cylinder 5 …… Bucket 6 …… Dump cylinder 7 …… Hydraulic pump 9 …… Dump cylinder directional control valve 10 …… Lift cylinder directional control valve 12 …… Control valve 17 …… Self Leveling valve 18 …… Shunt valve 19 …… Switching valve 25 …… Bypass line 30 …… Shunt valve 31 …… Switching valve 38 …… Bypass line

Claims (1)

(57) [Claims] 1. A self-leveling valve is provided downstream of a control valve including a directional control valve for a lift cylinder and a directional control valve for a dump cylinder in the form of a series circuit.
The hydraulic oil sent from the lift cylinder when the boom is raised or lowered is split into a regulated flow rate and a surplus flow rate by the flow dividing valve of the self-leveling valve at a predetermined ratio, and the adjusted flow dividing oil is sent to the dump cylinder to automatically move the bucket. A boom and bucket control device for a shovel loader capable of horizontal adjustment, wherein a directional control valve for a dump cylinder in the control valve is provided upstream of a directional control valve for a lift cylinder. Boom and bucket control device for a shovel loader configured to supply hydraulic oil prior to the dump cylinder and to supply oil spilled from the dump cylinder to the lift cylinder during simultaneous operation of.