JP2002339917A - Working machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that, when attaching an emergency cutoff mechanism to a pipe attachment part of a hydraulic actuator, the emergency cutoff mechanism is large and easily damaged by abutting on an obstacle. SOLUTION: This working machine is provided with a control valve 30 controlling an operation of the hydraulic actuator 29, a safety valve 36 preventing overload of a control valve, and an emergency cutoff valve 37 stopping the hydraulic actuator, when a pipe connected to the hydraulic actuator is damaged. The emergency cutoff valve 37 is provided with a cutoff prevention part 39 preventing the operation of the emergency cutoff valve, when operating the hydraulic actuator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique of a stop device for preventing a hydraulic excavator or a hydraulic crane from falling due to breakage of a hydraulic pipe.

[0002]

2. Description of the Related Art Heretofore, there has been a conventional construction in which a bucket is attached to the tip of an arm of a backhoe to perform excavation work, or a hook is provided at a base of the bucket for crane work. In such a backhoe, if the pipe connected to the boom cylinder or the arm cylinder is broken during crane work, not only the boom or the arm pivots in the dropping direction and damages the suspended object, but also the backhoe body. To prevent damage, a fall prevention device is provided.

[0003] This fall prevention device can be mainly classified into two types. In the first method, as shown in FIG. 6, a check valve 42 and a shutoff valve 43 are connected in parallel to a port 41 on the lifting side of a hydraulic cylinder 40 serving as a hydraulic actuator, and the check valve 42 and the shutoff valve 43 Hydraulic cylinder 4
0 and the pilot type switching valve 45.
The pilot-type switching valve 45 is provided with an operation lever 46.
, The remote control valve 47 serving as a pilot operation valve is switched to send the pilot oil pressure to the operation unit and switch. In this way, the shut-off valve 43 is normally located at the block position and is shut off, and when the piping is broken, the check valve 42 and the shut-off valve 43 prevent the hydraulic pressure in the cylinder 40 from dropping out and prevent the cylinder 40 from dropping. Was. As such a technique, there is a technique disclosed in JP-A-6-94004 or JP-A-9-32044.

In the second method, as shown in FIG. 7, an emergency shutoff valve 49 is connected to a port 41 on the lifting side of a hydraulic cylinder 40.
Was connected. As shown in FIG. 9, the emergency shutoff valve 49 houses a poppet 51 in a valve case 50, and the poppet 51 is urged to the open side by a spring 52, and the hydraulic flow rate on the hydraulic cylinder 40 side increases, Poppet 51
The poppet 51 closes when the pressure difference (ΔP1−ΔP2) before and after the pressure becomes larger than the spring force. In this way, when the pipe is broken, the flow rate on the cylinder side suddenly increases and the emergency shutoff valve 49 is closed to prevent the pipe from falling. As the configuration of such an emergency shut-off valve, there are techniques of actual climbing No. 2584755 and actual climbing number of 30020827.

[0005]

When excavation work is performed by a backhoe, a large impact may be applied to the work equipment. Therefore, it is necessary to prevent the strength member of the work equipment and hydraulic equipment from being damaged by the impact force. It is common practice to provide a safety valve for absorption. When this safety valve is incorporated in the first type hydraulic circuit, as shown in FIG.
It is necessary to arrange a safety valve 44 between the hydraulic cylinder 40 and the shutoff valve 43, and these check valve 42, shutoff valve 43,
The installation space for arranging the safety valve 44 and the like becomes large, and as shown in FIG. 8, a valve case is arranged outside the hydraulic cylinder and covered with covers 53 to prevent damage from outside. . However, the appearance was poor, and the protrusion from the cylinder was inevitable, and the protruding portion was in contact with an obstacle such as a side wall during excavation during work. Further, the safety valve 44 requires a pipe for returning the return oil to the tank, and the hydraulic pipe is also increased.

In the case of the second method, when the excavation work and the crane work can be combined, it is necessary to increase the expansion / contraction (work) speed of the hydraulic cylinder in order to secure the amount of earthwork during the excavation work. The set flow rate of the emergency shut-off valve, that is, the flow rate when the poppet closes, needs to be increased. However, if the set flow rate is set large,
If the piping breaks during crane operation, the flow will be cut off at the point when the falling speed increases due to the large set flow rate, and when the falling speed is increased, it will be stopped suddenly. Is transmitted to this machine, not only to the operator, but also to the operator.
It was also losing the balance of this machine.

[0007]

The present invention employs the following means in order to solve the above-mentioned problems. First, in claim 1, a control valve for controlling the operation of the hydraulic actuator and a safety valve for preventing the control valve from overloading, and an emergency shut-off for stopping the hydraulic actuator when a pipe connected to the hydraulic actuator is broken. In a work machine equipped with a valve, the emergency shut-off valve is provided with a shut-off prevention unit for preventing the operation of the emergency shut-off valve when a hydraulic actuator is operated.

According to a second aspect of the present invention, the shutoff preventing portion is connected to a pilot operated valve for operating the control valve.

According to a third aspect of the present invention, a pilot oil path is communicated between a poppet constituting a valve body of the emergency shutoff valve and a piston constituting a shutoff preventing portion.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to the accompanying drawings, using a work machine as a backhoe. 1 is an overall side view of a backhoe equipped with an emergency shutoff valve according to the present invention, FIG. 2 is a hydraulic circuit diagram for operating a hydraulic actuator, FIG. 3 is a hydraulic circuit diagram to which a specific example of the emergency shutoff valve is applied, FIG. 4 is an enlarged sectional view of the emergency shutoff valve, and FIG. 5 is a reference hydraulic circuit diagram.

First, a schematic configuration of a working machine according to the present invention will be described using a backhoe as an embodiment. As shown in FIG. 1, the backhoe rotatably supports a revolving frame 8 via a revolving table bearing 7 having a vertical axis at the upper center of the crawler-type traveling device 1. A blade 10 is disposed at one end in the front and rear directions so as to be vertically rotatable. A bonnet 9 for covering an engine or the like is provided on a rear portion of the revolving frame 8, and a support frame of a canopy 22 is erected from the hood 9 to cover an operation unit.

A work machine 2 is mounted on the front end of the revolving frame 8, and the work machine 2 has a boom bracket 12 attached to the front end of the revolving frame 8 so as to be rotatable left and right.
The lower end of the boom 6 is supported by the boom bracket 12 so as to be rotatable back and forth. The boom 6 is bent forward in the middle, and is formed in a substantially “C” shape in side view. An arm 5 is rotatably supported at the other end of the boom 6, and a bucket 4 as a work attachment is rotatably supported at the tip of the arm 5. The hook 3 is attached to the pivot pin 14 on the back side of the bucket 4.
Are pivotally supported so that a load 20 can be hung on the hook 3.

A boom cylinder 23 serving as a hydraulic actuator is interposed between the boom bracket 12 and a boom cylinder stay 6a provided on a front surface of the boom 6 in the middle, and an arm cylinder provided on a back surface of the boom 6 in the middle. An arm cylinder 29 serving as a hydraulic actuator is interposed between the stay 6b and a bucket cylinder bracket 27 provided at the base end of the arm 5, and a stay 11 connected to the bucket cylinder bracket 27 and the bucket 4 is provided.
, A bucket cylinder 24 is interposed.

Thus, the boom 6 is rotated by the expansion and contraction of the boom cylinder 23, the arm 5 is rotated by the expansion and contraction of the arm cylinder 29, and the bucket 4 is rotated by the expansion and contraction of the bucket cylinder 24. The boom cylinder 23, the arm cylinder 29, and the bucket cylinder 2
4 is composed of hydraulic cylinders, each of the cylinders 23, 29,
Reference numeral 24 is driven by operation of an operation lever disposed in the operation unit to switch a switching valve disposed below the operation lever and supply hydraulic oil from a hydraulic pump to be driven to expand and contract.

A swing cylinder (not shown) is disposed on the side of the swing frame 8, and its base is pivotally supported by the swing frame 8. The tip of the cylinder rod of the swing cylinder is connected to the boom bracket 12. The boom bracket 12 can be rotated left and right with respect to the turning frame 8 by the swing cylinder, and the work implement 2 can be rotated left and right.

The turning frame 8 can be turned 360 degrees left and right by the operation of a hydraulic motor provided above the turning table bearing 7, and the blade 10 is connected to the rear portion of the discharge plate and the track frame of the crawler type traveling device 1. It can be moved up and down by the operation of a blade cylinder interposed between them. Further, traveling hydraulic motors 15 are disposed inside driving sprockets disposed on one side of the front and rear of the track frame, so that the crawler traveling device 1 can be driven to travel.

In such a backhoe, a hydraulic circuit for preventing the hydraulic actuator of the present invention from falling when the piping is broken will be described with reference to FIG. First, the main hydraulic pump 31 is connected to the output shaft of the engine housed in the hood 9.
And the charge pump 32 are connected and driven in parallel. A relief valve 34 for setting an output oil pressure is connected in parallel to a discharge-side main oil passage 33 of the main hydraulic pump 31,
The main oil passage 33 is connected to the control valve 30 via a check valve 35.

The control valve 30 is constituted by a pilot-operated 6-port three-position switching valve, and the secondary side has an oil passage (piping) 25 communicating with a bottom chamber 29a of the arm cylinder 29 and an oil passage (piping) communicating with a rod side chamber 29b. Piping)
26 are connected. A safety valve 36 is connected in parallel to an oil passage 26 communicating with a rod side chamber 29b (lifting side) for supplying pressure oil when lifting, and an emergency shutoff valve 37 is connected in series. The safety valve 36 has substantially the same configuration as the relief valve, the emergency shutoff valve 37 has a communication position and a block position, and the poppet can be urged to the communication side by a spring and held on the communication side by pilot oil pressure described later. If the flow rate from the rod side chamber becomes large, that is, if the pipe is broken during lifting, the spool moves to the block side and is switched to the closing side. The specific configuration of the emergency shutoff valve 37 will be described later.

A relief valve 61 for setting an output oil pressure is connected in parallel to a discharge oil passage 60 of the charge pump 32, and pilot discharge valves 62 and 63 serving as remote control valves are connected to the discharge oil passage 60. The pilot operation valves 62 and 63 are switched by a rotation operation of an operation lever 64 provided in an operation unit. The pilot operation valves 62 and 63 are two-position switching valves, and the secondary side is connected to the operation parts 30b and 30a of the control valve 30 via pilot oil passages 65 and 66, respectively.
The operating section 37a of the emergency shut-off valve 37 (the shut-off preventing section 3)
9).

In such a configuration, when the load 20 is locked and lifted by the hook 3, when the operation lever 64 is turned to the lifting side (direction A), the pilot operation valve 63 is switched, and the charge pump 32 is switched. From the discharge oil passage 60 to the pilot oil passage 66 via the pilot operation valve 63, and is sent to the operation portion 30a of the control valve 30 for switching. When the control valve 30 is switched to the (A) side, the pressure oil from the main hydraulic pump 31 is supplied to the rod side chamber 29b of the arm cylinder 29 via the emergency cutoff valve 37, and the arm cylinder 29 is contracted. Thus, the luggage 20 can be lifted.

When the operation lever 64 is turned in the downward (B) direction while the load 20 is lifted, the pilot operation valve 62 is switched, and the pressure oil from the charge pump 32 is discharged from the discharge oil passage 60 through the pilot oil passage 60. It flows to the pilot oil passage 65 through the operation valve 62 and the control valve 30
Is switched to the operation unit 30b. When the control valve 30 is switched to the (b) side,
The pressure oil from the main hydraulic pump 31 is supplied to the arm cylinder 29
Is fed to the head side chamber 29a, the arm cylinder 29 is extended to lower the load 20, and the rod side chamber 29b
The hydraulic oil inside is drained to the tank via the emergency shutoff valve 37.

When the arm cylinder 29 is rapidly extended (the load 20 is unloaded), when the hydraulic oil in the rod side chamber 29b flows through the emergency shutoff valve 37, the pilot oil passage 3
Attempts to switch to the block side with pressure oil from 7b,
The hydraulic pressure of the pilot oil passage 65 is controlled by the operation unit 3 of the emergency shutoff valve 37.
Since it is at 7a, the communication position is maintained, and the load can be unloaded without hindrance. In addition, when an excessive amount of hydraulic oil flows or the hydraulic pressure becomes high at the time of the descent, the safety valve 36 is operated to protect the pressure from becoming excessive.

When the operating lever 64 is at the neutral position,
The pressure oil from the discharge oil passage 60 is blocked, and no pressure oil is supplied to the pilot oil passages 65 and 66.
66 is connected to the tank and drained. Further, the control valve 30 is also in the neutral position, and the oil passages 25 and 26
Is also blocked, and the arm cylinder 29 is held at the position at the time of the neutral operation. When the pipe is broken at the neutral position, the hydraulic oil in the rod side chamber 29b quickly flows out, but the emergency shutoff valve 37 is switched to the block position by the pressure oil from the pilot oil passage 37b to prevent the oil from flowing out. At this time, since no pressure oil is supplied to the pilot oil passage 65, the pilot oil is not supplied to the operation unit 37a, and the operation can be switched by the pressure oil from the pilot oil passage 37b.

Next, a specific configuration of the emergency shutoff valve 37 will be described with reference to FIGS. The emergency shutoff valve 37 has a valve case 70 and a cylinder case 71 connected and arranged on the same axis, and the valve case 70 is formed of a T-shaped pipe.
One end of the straight portion communicates with the cylinder case 71, and the other end connects with a pipe as a primary port 70a for connection to the control valve 30. It is connected to an actuator (hydraulic cylinder) via the next port 70b. A poppet 72 and a spring 73 are provided in the valve case 70.
The poppet 72 has a valve body 72a at one end to close the primary port 70a.
3 urges the primary port 70a to open. The spring force of the spring 73 is set such that the poppet 72 is closed when the flow rate increases rapidly due to breakage of the pipe. On the other side of the poppet 72, a connecting rod 72b is arranged on the axis and protrudes and is inserted into the cylinder case 71. A communication hole 72c is opened in the poppet 72 in parallel with the axis so that the back chamber 70c can communicate with the primary and secondary ports.

The cylinder case 71 is formed in a pipe shape, one end of which is inserted into the valve case 70, and the connecting rod 72b is slidably penetrated through the axis thereof. The other end is closed by a plug member 74 and houses a piston 75 therein. The rod side chamber 71 a of the cylinder case 71 is communicated with the pilot oil passage 65.

In such a configuration, at the time of raising operation, pressure oil flows from the primary side port 70a to the secondary side port 70b, and the poppet 72 is opened to maintain the communication state. At the time of the lowering operation, pressure oil flows from the secondary port 70 to the primary port 70a, and the constricted portion 72 of the poppet 72 flows.
Due to the surface pressure of d, the poppet 72 attempts to move in the closing direction by overcoming the spring force. However, since the pressure oil from the pilot oil passage 65 is supplied to the rod chamber side 71a, the poppet 72 closes without sliding. Never. And, at the time of neutral, since the pilot oil passage 65 is drained,
The hydraulic oil leaked from between the cylinder case 71 and the connecting rod 72b is drained from the pilot oil passage, and
In the case where the pressure oil does not stay in the pipe 1a and the pipe is broken at the neutral position, the poppet 72 slides in the closing direction by overcoming the spring force. At this time, the pressure oil in the rod side chamber 72b is drained. Then, it can slide smoothly and close instantly.

It is conceivable that the emergency shutoff valve 37 is constructed as shown in FIG. That is, the emergency shutoff valve 37 '
Is constructed such that the poppet 72 'and the piston 75' are formed separately and slidably arranged, and the pilot oil passage 65 is connected to the piston 7 '.
It communicates with the back side of 5 '. In this manner, at the time of operation, the poppet 72 ′ can be urged to the open side by the rod portion 75 a protruding from the piston 75 ′ by the pressure oil from the pilot oil passage 65, but the leak oil from the rod portion 75 a enters the piston side. Since the pilot oil pressure is not so high, it cannot be pushed out completely, and the necessity of providing the drain 76 arises. As in the conventional case, it is preferable to form a pilot oil passage between the poppet 72 and the piston 75.

[0028]

As described above, the present invention has the following advantages. First, a control valve for controlling the operation of the hydraulic actuator and a safety valve for preventing overload are provided in the control valve,
When the piping connected to the hydraulic actuator is broken,
In a work machine having an emergency shut-off valve for stopping a hydraulic actuator, the emergency shut-off valve is provided with a shut-off preventing unit for preventing the operation of the emergency shut-off valve when the hydraulic actuator is operated, so that a check valve or a safety valve is provided. This eliminates the need to provide such components at the piping connection near the actuator, thus making it possible to make the system compact and making it difficult for the emergency shut-off valve to hit obstacles or the like during operation. Then, when the pipe is broken, etc., the shutoff function can be surely exhibited.

Further, since the shut-off preventing portion is connected to the pilot-operated valve for operating the control valve, the oil passage to the actuator is operated by the shut-off preventing portion when the control valve is operated. Without interrupting, the actuator can be reliably operated by effectively utilizing the pilot hydraulic pressure.

Further, since the pilot oil passage is communicated between the poppet constituting the valve element of the emergency shut-off valve and the piston constituting the shut-off preventing portion, the poppet and the piston are connected. Leakage oil from the gap between the rods can be drained from the pilot oil passage, so that the drain oil passage is not required and the operation of the piston is not hindered.

[Brief description of the drawings]

FIG. 1 is an overall side view of a backhoe equipped with an emergency shutoff valve according to the present invention.

FIG. 2 is a hydraulic circuit diagram for operating a hydraulic actuator.

FIG. 3 is a hydraulic circuit diagram to which a specific example of the emergency shutoff valve is applied.

FIG. 4 is an enlarged sectional view of the emergency shutoff valve.

FIG. 5 is a reference hydraulic circuit diagram.

FIG. 6 is a hydraulic circuit diagram having a conventional first type emergency shutoff valve.

FIG. 7 is a hydraulic circuit diagram having a conventional second type emergency shutoff valve.

FIG. 8 is a side view of a backhoe equipped with a first type emergency shutoff valve.

FIG. 9 is a sectional view of a first type emergency shutoff valve.

[Explanation of symbols]

 29 Arm cylinder 30 Control valve 36 Safety valve 37 Emergency shut-off valve 39 Shut-off prevention unit 39

Continued on front page F term (reference) 2D003 AA01 AB03 AC06 BA01 BA07 CA02 DA03 DB02 3H060 AA01 BB08 CC02 DA02 DC05 DD05 DD11 EE04 GG16 HH04 HH18 3H082 AA02 AA18 AA23 AA25 BB17 CC02 DA23 DA37 DA46 EE01

Claims (3)

[Claims] 1. A control valve for controlling operation of a hydraulic actuator, a safety valve for preventing overload of the control valve, and an emergency shut-off valve for stopping the hydraulic actuator when a pipe connected to the hydraulic actuator is broken. The work machine according to claim 1, wherein said emergency shut-off valve is provided with a shut-off preventing portion for preventing operation of said emergency shut-off valve when a hydraulic actuator is operated. 2. The work machine according to claim 1, wherein the shut-off preventing unit is connected to a pilot operation valve that operates the control valve. 3. The working machine according to claim 1, wherein a pilot oil passage is communicated between a poppet constituting a valve body of the emergency shutoff valve and a piston constituting a shutoff preventing portion.