JPH07300881A - Oil-hydraulic circuit of back hoe - Google Patents

Abstract

PURPOSE:To prevent rapid falling of a suspended cargo by merely changing a part of an oil-hydraulic circuit of an actuator system without requiring newly providing a winch and a hydraulic motor for driving the winch which provide a function of a crane as required in a conventional back hoe, without lowering the original function of the back hoe even in the case of happening such a trouble that a flexible hose is injured and oil flows out therefrom, when the back hoe is used as a crane in an operation other than excavation operation. CONSTITUTION:An oil-hydraulic circuit for using a back hoe as a crane is provided at the end side of flexible hoses 6, 7 of a back hoe, which circuit is branched off an original oil-hydraulic circuit of the back hoe. A counter-balance valve 10 for preventing a cargo from rapidly falling is provided midway in the oil-hydraulic circuit for use as a crane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit of a backhoe, which is a civil engineering work machine, for excavating earth and sand from a front side by using a bucket, and more specifically, it has a crane function for off-purpose use. The hydraulic circuit of the backhoe.

[0002]

2. Description of the Related Art In addition to the original excavation work, when a backhoe is used as a crane for lifting loads, a regulation concerning the restriction of the use of so-called vehicle construction machinery outside the intended use is provided in Article 164 of the Industrial Safety and Health Regulations. There is.

According to Article 164, Paragraph 2 of the same regulation, (1) When the nature of the work is unavoidable, that is, in order to reduce the risk of soil collapse as part of the excavation work, a temporary earth stop sheet pile is used. (2) When it is necessary to perform safe work, that is, when the work area is narrow and the work is carried in with a mobile crane, the work area becomes more complicated and the danger increases. If possible, the regulation stipulates that the load can be lifted by the backhoe as long as the specified conditions are complied with.

A technique related to this type of backhoe is described in, for example, Japanese Utility Model Laid-Open No. 56-73771.

[0005]

By the way, the bucket cylinder 1, the arm cylinder 2, and the boom cylinder 3 of the backhoe shown in FIG. 9 are so-called telescopic machines that perform reciprocating movements in the front-rear direction to perform a predetermined operation. For,
A rigid metal pipe cannot be used as a conduit for supplying pressure oil to these, and a flexible hose (generally a high-pressure rubber hose) that can follow the reciprocating motion of each cylinder is used. .

Degradation of the flexible hose, which is repeatedly stressed when the backhoe is used, is relatively quick, and it is usual that the flexible hose is obliged to be added to the safety inspection obligation (regular voluntary inspection) of the backhoe. However, it is very difficult to know exactly when to replace a hose unless the hose is clearly visible.

Under such circumstances, when the backhoe is used outside of its intended purpose, that is, when it is used as a crane for lifting loads, the previous occupational health and safety regulations stipulate that no one should be allowed to enter within the working radius. However, in the actual work, the wire rope or the hanging chain is slung while the engine is running, or the operator directly guides the suspended load without using the guide rope. In such a case, if the flexible hose is damaged due to some reason, it will be suspended from the bucket hook indicated by reference numeral 4 in FIG. 9 due to oil leakage from the cylinder. This includes the risk that the cargo 5 will fall rapidly, damage the body of the truck, and, in the worst case, cause a personal injury.

The cause of the trouble in the hydraulic pressure supply system may be an emergency stop of the hydraulic pump or an insufficient amount of oil in the hydraulic tank, in addition to the breakage of the flexible hose.

In order to prevent the sudden drop of the suspended load as described above, it is conceivable to provide a counter balance valve for applying back pressure to the cylinder located at the tip of the flexible hose.

However, as described above, the backhoe is used as a crane for the original purpose of the backhoe, which is required to exert the maximum force downward when excavating the soil from the front side to the front side with the bucket for excavating. The counterbalance valve as a suspended load drop preventing means when used results in impairing the original function of the backhoe, that is, the function of exerting the maximum force downward, and eventually reduces the original excavation work capacity of the backhoe. It causes the problem of causing it.

Incidentally, Japanese Utility Model Laid-Open No. 56-73771 entitled "Hydraulic circuit of backhoe having a crane function" discloses:
By installing a pilot check valve in the lifting circuit of the hydraulic circuit for the arm cylinder and boom cylinder that blocks the flow of oil in the direction in which the arm and boom descend, an abnormal load acts on the arm and boom, causing an arm cylinder And, when abnormal pressure is generated in the raising circuit of the boom cylinder and the hoses of both cylinders are damaged due to this abnormal pressure, a technology for preventing the arm and the boom from falling by the both pilot check valves is disclosed. Has been done.

However, the technique described in the publication is to newly install a winch that controls the crane function, and further, a hydraulic motor for driving the winch, which is greatly different from the present invention described later in this respect. As a result, the backhoe cost is high.

The object of the present invention is to use the backhoe for purposes other than the original excavation work, that is, when the backhoe is used to lift a load as a crane in addition to the original excavation work. Even when assuming a hydraulic supply system trouble such as oil breakage due to breakage, the original function of the backhoe, that is, when excavating the soil from the front by the bucket to the front, the maximum force is downward. There is no need to newly install a winch that controls the crane function and a hydraulic motor for driving the winch as in the past, as it has a part of the hydraulic circuit of the actuator system. To provide an improved backhoe hydraulic circuit that can prevent a sudden drop of a suspended load by simply changing it. A.

[0014]

In the backhoe for excavating the sand from the front by the bucket, the backhoe is branched from the original hydraulic circuit of the backhoe to the tip side of the flexible hose of the actuator system. This is achieved by providing a hydraulic circuit for use as a crane that is not used for the purpose, and providing a means for preventing a sudden drop of a suspended load in the middle of the hydraulic circuit on the tip side of the flexible hose used for a crane.

[0015]

In the above construction, when the backhoe incorporating the circuit of the present invention is used for the original purpose of the backhoe, the original function of the backhoe, that is, when excavating the soil from the front to the front by the bucket, It exerts its maximum force toward the outside and excels in excavation workability.

Further, when the backhoe incorporating the circuit of the present invention is used outside the intended purpose, that is, when it is used as a crane for lifting loads, the flexible hose of the actuator system should be damaged by some reason and oil should be removed. Even if a hydraulic supply system trouble such as an outflow occurs, a dedicated circuit as a crane provided at the tip side of the flexible hose, that is, a hydraulic circuit provided by branching from the original hydraulic circuit of the backhoe Suspended load rapid fall prevention means installed at

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to one embodiment shown in FIGS.

FIG. 1 shows the flow of oil when the backhoe incorporating the circuit of this embodiment is used as a crane for the purpose of extra-application use.

FIG. 2 shows the oil flow in the opposite direction to that of FIG.

FIG. 3 shows the flow of oil when the backhoe incorporating the circuit of this embodiment is used for the original purpose of the backhoe.

FIG. 4 shows the flow of oil in the opposite direction to FIG.

1 to 4, reference numerals 6 and 7 denote flexible high pressure rubber hoses for supplying pressure oil to the actuator (bucket cylinder, other cylinder) system of the backhoe and following the reciprocating motion of the actuator. , Which are located on the tip side of the high-pressure rubber hoses 6 and 7, and are provided in the hydraulic circuits between the high-pressure rubber hoses 6 and 7 and the cylinder 8, respectively, of an electromagnetic center bypass type switching valve 9, a counter balance valve 10, and a check valve. 11, relief valve 1
2, double pilot check valves 13, 14 and a pressure switch 15 are installed as shown.

In the illustrated embodiment, the electromagnetic center bypass type switching valve 9 to the pressure switch 15 are connected as one block unit via flanges 16 to 19, respectively.

When the backhoe incorporating the circuit of the present embodiment is used for the original purpose of the backhoe in the above-mentioned configuration, the oil flow in one direction is as shown by the arrow in FIG. The flow of oil in the opposite direction is as shown by the arrow in FIG.

That is, in FIG. 3, the pressure oil that has passed through the high pressure rubber hose 6 passes through the pilot check valve 13 → the cylinder 8 → the pilot check valve 14 → B of the electromagnetic center bypass type switching valve 9 → A, and the high pressure rubber hose 7 side. Then, the piston rod 20 of the cylinder 8 is moved in the direction of arrow a in the figure.

In FIG. 4, the pressure oil that has passed through the high-pressure rubber hose 7 passes through the electromagnetic center bypass type switching valve 9 A → B → pilot check valve 14 → cylinder 8 → pilot check valve 13 to the high-pressure rubber hose 6 side. Then, the piston rod 20 of the cylinder 8 is moved in the direction of arrow b in the figure.

On the other hand, when the backhoe incorporating the circuit of this embodiment is used as a crane for the purpose of non-use, the unidirectional oil flow is as shown by the arrow in FIG. The flow of oil in the opposite direction is as shown by the arrow in FIG.

That is, in FIG. 1, the pressure oil that has passed through the high-pressure rubber hose 6 has a pilot check valve 13 → cylinder 8 → pilot check valve 14 → B of the electromagnetic center bypass type switching valve 9 → B ′ → counter balance valve 1.
0 to the high pressure rubber hose 7 side via A ′ → A of the electromagnetic center bypass type switching valve 9, and the piston rod 20 of the cylinder 8 is moved in the direction of arrow a in the figure.

In FIG. 2, the pressure oil that has passed through the high-pressure rubber hose 7 is A → A ′ of the electromagnetic center bypass type switching valve 9 → check valve 11 → B ′ → B of the electromagnetic center bypass type switching valve 9. → Double pilot check valve 14
-> Cylinder 8-> The high-pressure rubber hose 6 side is reached via the pilot check valve 13, and the piston rod 20 of the cylinder 8 is moved in the direction of arrow b in the figure.

The relief valve 12 operates when a pressure higher than a preset value is applied to it, that is, when the backhoe is used for a crane and an overload is applied to the relief valve 12, and a part of the pressure oil is discharged. Protect the hydraulic circuit system by leaking.

The pressure switch 15, like the relief valve 12, is turned on when a pressure higher than a preset value is applied thereto, that is, when the backhoe is used for a crane and an overload is applied thereto. , An alarm device (not shown) (sound, lamp, or a combination thereof) is activated to call attention to the operator and others.

5 to 8 show another embodiment of the present invention,
In this embodiment, an electromagnetic normally open type shutoff valve 21 and an electromagnetic normally closed type shutoff valve 22 are used in place of the electromagnetic center bypass type switching valve 9 of the first embodiment. The case is illustrated.

That is, the normally open type shut-off valve 21 includes the high pressure rubber hoses 6 and 7 of the actuator system.
Located on the tip side of the backhoe, the first hydraulic circuit of the backhoe.
It is installed in the tier.

The normally-closed shutoff valve 22 is also located at the tip of the high pressure rubber hoses 6 and 7 of the actuator system and is installed at the first stage of the hydraulic circuit using the backhoe as a crane. .

When the backhoe incorporating the circuit of the present embodiment is used for the original purpose of the backhoe in the above-mentioned configuration, the oil flow in one direction is as shown by the arrow in FIG. The flow of oil in the opposite direction is as shown by the arrow in FIG.

That is, in FIG. 7, the pressure oil that has passed through the high pressure rubber hose 6 passes through the pilot check valve 13 → cylinder 8 → pilot check valve 14 → electromagnetic type normally open type shutoff valve 21 and the high pressure rubber hose 7
To the side, the piston rod 20 of the cylinder 8 is moved in the direction of arrow a in the figure.

In FIG. 8, the pressure oil that has passed through the high-pressure rubber hose 7 is electromagnetic normally open type shutoff valve 21 → pilot check valve 14 → cylinder 8 →
It goes through the pilot check valve 13 to the high pressure rubber hose 6 side, and connects the piston rod 20 of the cylinder 8 to the arrow b in the figure.
Move in the direction.

On the other hand, when the backhoe incorporating the circuit of this embodiment is used as a crane for the purpose of non-use, the unidirectional oil flow is as shown by the arrow in FIG. The flow of oil in the opposite direction is as shown by the arrow in FIG.

That is, in FIG. 5, the pressure oil that has passed through the high-pressure rubber hose 6 is pilot check valve 13 → cylinder 8 → pilot check valve 14 → single auto pilot check valve 23 → counter balance valve 10 →
The piston rod 20 of the cylinder 8 is moved in the direction of arrow a in the figure through the electromagnetic normally closed shutoff valve 22 to reach the high pressure rubber hose 7 side.

In FIG. 6, the pressure oil that has passed through the high pressure rubber hose 7 is electromagnetic normally closed shutoff valve 22 → check valve 11 → pilot check valve 14
-> Cylinder 8-> The high-pressure rubber hose 6 side is reached via the pilot check valve 13, and the piston rod 20 of the cylinder 8 is moved in the direction of arrow b in the figure.

In the embodiments of FIGS. 5 to 8, the electromagnetic normally open type shutoff valve 21 and the normally closed type shutoff valve 22 are replaced with each other, that is, the original hydraulic circuit of the backhoe and the backhoe are used for other purposes. As a switching valve for switching the hydraulic circuit when used as a crane, the electromagnetic normally closed shut-off valve 22 is installed in the original hydraulic circuit of the backhoe, and the hydraulic circuit when the backhoe is used as a crane that is not used Alternatively, the electromagnetic normally open type shutoff valve 21 may be installed.

As is apparent from the description of the illustrated embodiment, according to the present invention, when the backhoe is used for its original purpose, the backhoe has its original function, that is, the bucket moves soil from the front to the front. When excavating by scratching, it exerts the maximum force downward and excels in excavation workability.

When the backhoe is used for other purposes,
That is, when using it as a crane to lift loads,
According to the present embodiment, the flexible hoses 6 and 7 provided on the tip side of the flexible hoses 6 and 7 can be provided even when troubles in the hydraulic supply system occur such that the flexible hoses 6 and 7 of the actuator system are damaged and oil flows out. A counterbalance valve 10 installed in the middle of a dedicated circuit as a crane, that is, a hydraulic circuit branched from the original hydraulic circuit of the backhoe prevents a suspended load from being rapidly dropped.

As shown in the illustrated embodiment, with the piston 24 of the cylinder 8 as an actuator as a boundary,
By connecting the double pilot check valves 13 and 14 to the hydraulic circuits in front of both chambers 26 and 27 formed on the left and right of the cylinder tube 25, not only when the backhoe is used as a crane which is not used, but also When used for the original excavation work of the backhoe, that is, the switching valve 9 of the electromagnetic center bypass type shown in FIGS.
Alternatively, regardless of switching between the electromagnetic normally open type shutoff valve 21 and the normally closed type shutoff valve 22 shown in FIGS. 5 to 8, the flexible hoses 6 and 7 are damaged and oil leaks, causing a trouble in the hydraulic supply system. In the event of occurrence of the above, the double pilot check valves 13 and 14 are locked at that point, the movement of the piston rod 20 is stopped, and the bucket or the load 5 shown in FIG. 9 is prevented from being rapidly dropped. Therefore, it is possible to further enhance the safety of this seed engineering work machine.

Further, the double pilot check valve 1
Cylinder 8 which is an actuator instead of 3, 14
9 of the hydraulic circuit immediately before both chambers 26, 27 formed on the left and right of the cylinder tube 25 with the piston 24 as a boundary, the hydraulic oil is immediately before the chamber on the pushing side when the bucket 27 of FIG. 9 rises. Even if the pilot check valve is connected to the hydraulic circuit, the same effect as described above can be obtained.

Regarding the safety when the backhoe is used for the original excavation work, paying attention only to the usage of the backhoe as a crane that is not used for the purpose, and focusing only on the safety in use as the crane. As long as it is the same as the conventional one, the double pilot check valves 13 and 14 of the illustrated embodiment, or the pilot check valves replacing the double pilot check valves 13 and 14 may be omitted.

However, by installing the double pilot check valves 13 and 14 of the illustrated embodiment or the pilot check valve as a substitute member thereof, these pilot check valves can be used as a crane whose backhoe is not used. In such a case, the counter balance valve 10 functions as a secondary protective device that is a protective device.
Further, the double pilot check valves 13 and 14 or the pilot check valve as a substitute member thereof functions as a safety device even when the backhoe is used for the original excavation work, and further enhances the safety of the seed civil work machine. Not only can it be enhanced, but the following additional effects can be achieved.

That is, even if the backhoe is stopped while the cylinder, which is the working machine, has been naturally lowered due to aging or other reasons, and the boom is extended in the horizontal direction, for example, the pilot described above is used. The check valve prevents the boom from dropping naturally, and even if a vehicle or other object is placed below the boom of the backhoe, it is possible to avoid the problem of damage to these objects.

Further, instead of the electromagnetic type center bypass type switching valve 9, the normally open type shutoff valve 21 and the normally closed type shutoff valve 22 shown in the illustrated embodiment, for example, an external hydraulic pilot operated type, an air pilot operated type. , Manually operated center bypass type switching valve,
A normally open type shutoff valve or a normally closed type shutoff valve may be used.

[0050]

As described above, according to the present invention, when the backhoe is used outside the intended use, that is, when the backhoe is used as a crane for lifting loads in addition to the original excavation work, the flexible hose of the actuator system causes some cause. Even if it is assumed that a hydraulic supply system trouble such as oil spillage due to damage due to a backhoe is expected, the original function of the backhoe, that is, when excavating the soil from the front by the bucket to the front, A hydraulic circuit for the actuator system that does not impair the function that exerts the maximum force, excels in excavation workability, and does not need to newly install a winch that controls the crane function as in the past and a hydraulic motor for driving the winch. It is possible to prevent the sudden drop of the suspended load by an extremely simple means of only changing a part.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a first embodiment showing a flow of oil when a backhoe incorporating the circuit of the present invention is used as a crane for the purpose of extra-application use.

FIG. 2 is a hydraulic circuit diagram showing an oil flow in a direction opposite to that of FIG.

FIG. 3 is a hydraulic circuit diagram of a first embodiment showing a flow of oil when a backhoe incorporating the circuit of the present invention is used for the original purpose of the backhoe.

FIG. 4 is a hydraulic circuit diagram showing an oil flow in a direction opposite to that of FIG.

FIG. 5 is a hydraulic circuit diagram of a second embodiment showing a flow of oil when a backhoe incorporating the circuit of the present invention is used as a crane for the purpose of extra-application use.

FIG. 6 is a hydraulic circuit diagram showing an oil flow in a direction opposite to that of FIG.

FIG. 7 is a hydraulic circuit diagram of a second embodiment showing a flow of oil when a backhoe incorporating the circuit of the present invention is used for the original purpose of the backhoe.

8 is a hydraulic circuit diagram showing the flow of oil in the opposite direction to FIG.

FIG. 9 is an external view of a backhoe.

[Explanation of symbols] 1 ... Bucket cylinder, 2 ... Arm cylinder, 3 ...
Boom cylinder, 4 ... bucket hook, 5 ... suspended load,
6, 7 ... High-pressure rubber hose, 8 ... Cylinder, 9 ... Electromagnetic center bypass type switching valve, 10 ... Counterbalance valve, 11 ... Check valve, 12 ... Relief valve, 13, 14
… Double pilot check valve, 15… Pressure switch,
16 to 19 ... Flange, 20 ... Piston rod, 21 ...
Electromagnetic normally open type shutoff valve, 22 ... Electromagnetic normally closed type shutoff valve, 23 ... Single auto pilot check valve, 24 ... Piston, 25 ...
Cylinder tube, 26, 27 ... Chamber, 28 ... Bucket.

Claims (6)

[Claims] 1. In a backhoe for excavating earth and sand from a front side by using a bucket, the backhoe is used as a crane that is not used for the purpose by branching from the hydraulic circuit of the backhoe to the tip side of a flexible hose of an actuator system. A hydraulic circuit for a backhoe, which is provided with a means for preventing a sudden drop of a suspended load in the middle of the hydraulic circuit on the tip side of the flexible hose used for a crane. 2. The hydraulic pressure of the backhoe as claimed in claim 1, wherein the means for preventing the sudden drop of the suspended load, which is provided in the middle of the hydraulic circuit used for the crane located on the tip side of the flexible hose, is a counterbalance valve. circuit. 3. The alarm device according to claim 1 or 2, which is turned on when a pressure equal to or higher than a preset value is applied to the hydraulic circuit when the backhoe is used as a crane which is not used for the purpose. Backhoe hydraulic circuit equipped with a pressure switch to activate the. 4. The method according to claim 1, wherein
A backhoe hydraulic circuit that connects a double pilot check valve to the hydraulic circuits in front of both chambers that are formed on the left and right of the cylinder tube, with the piston of the cylinder that is the actuator as the boundary. 5. The method according to any one of claims 1 to 3,
Of the hydraulic circuits in front of both chambers formed on the left and right of the cylinder tube with the piston of the cylinder, which is the actuator as the boundary, install a pilot check valve in the hydraulic circuit in front of the chamber where the hydraulic oil is pushing out when the bucket rises. Connected backhoe hydraulic circuit. 6. A backhoe comprising the hydraulic circuit according to claim 1.