JP2571190Y2 - Hydraulic circuits such as power shovels - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit such as a power shovel. More specifically, the present invention relates to a hydraulic circuit to be added to an existing hydraulic circuit when a separate function is added to an existing hydraulic drive mechanism of the power shovel, and a power shovel to which such a hydraulic circuit is applied.

[0002]

2. Description of the Related Art A construction machine such as a power shovel uses a hydraulic actuator having a large power for turning, raising and lowering an arm, and tilting a bucket. The hydraulic pressure source uses the rotation of an engine. On the other hand, the plurality of actuators are usually rarely operated simultaneously, and the operator sequentially turns, moves up and down the arm, and the like. Therefore, it is desired to drive a large number of actuators from a small number of hydraulic pumps, and for that purpose, various devices have been proposed (for example, Japanese Patent Application Laid-Open Nos. 57-127006 and 58-3).
3649, JP-A-61-83728).

[0003]

[Problems to be Solved by the Invention] By the way, recent power shovels are not only used to load earth and sand into dump trucks with buckets, but also to transport wood and concrete pieces, and to dismantle houses. Some have a solve bucket facing the bucket body, and others have the bucket wrist rotated (rotated like a wrist twist). These additional functions can be controlled by providing separate hydraulic units and control valves,
As described above, it is desired to share a basic power shovel as much as possible without increasing the number of hydraulic pumps and the like.
In the present invention, the term "power shovel or the like" refers to a large excavation loading machine comprising a traveling unit, for example, a rotatable cab mounted on a crawler, and a boom having a vertically movable dipper. This is a general-purpose shovel excavator that can be used for various tasks by exchanging it.

In this case, for example, another directional control valve is interposed in parallel with a directional control valve for a bucket tilting operation in a basic power shovel, and the two directional control valves are switched to perform the tilting operation of the bucket. It is also conceivable to control the opening and closing of the solve bucket. However, in such a case, there is a problem that the number of operation means increases and the operation means becomes complicated, and if the operation is performed simultaneously, the amount of oil supply becomes insufficient, so that the respective operation parts cannot be quickly operated. Under such circumstances, the present invention can ensure sufficient work efficiency when adding a new function to a power shovel, and can easily add a power shovel to a basic hydraulic circuit. It is an object of the present invention to provide a hydraulic circuit.

[0005]

The hydraulic circuit according to the present invention has two hydraulic circuits.
A plurality of hydraulic actuators that reciprocate by sending pressure oil to one of the pipelines and returning from the other, and selectively alternately communicate the first outlet and the second outlet to a pressure oil source or a return pipe, respectively. A directional control valve, a first port communicating with a first outlet of the directional control valve, a second port communicating with one conduit of the first hydraulic actuator, and communicating with one conduit of the second hydraulic actuator. A first three-way switching valve having a third port for selectively communicating the first port with the second port or the third port, a first port communicating with the second outlet of the directional control valve, a first hydraulic pressure; A second port communicating with the other channel of the actuator and a third port communicating with the other channel of the second hydraulic actuator, wherein the first port is selectively communicated with the second port or the third port; Let the second A hydraulic circuit comprising a one-way switching valve and an interlocking switching mechanism for switching between the first three-way switching valve and the second three-way switching valve while synchronizing the one-way switching valve with one pipe of the first or second hydraulic actuator The first and second three-way switching valves are connected to the first and second hydraulic actuators by connecting the first and second three-way switching valves to the first and second hydraulic actuators. When switched to operate, the on-off valve is configured to open for a certain period of time.

In the hydraulic circuit of the first aspect, a first hydraulic cylinder for tilting the bucket body, a second hydraulic cylinder for opening and closing the solve bucket, and a first hydraulic motor for turning the power shovel body are provided. A hydraulic circuit having a second hydraulic motor for rotating the rotating buckets in a wrist, and alternately using the first hydraulic cylinder and the second hydraulic cylinder for use; a first hydraulic motor and a second hydraulic motor;
It is desirable to alternately use the hydraulic motor.

The additional hydraulic circuit according to the present invention is a hydraulic circuit according to claim 2, which is added to the existing hydraulic circuit when a separate function is added to the existing hydraulic drive mechanism such as a power shovel. A hydraulic circuit for opening and closing the bucket and a hydraulic circuit for rotating the wrist of the rotating bucket are unitized. And such a hydraulic circuit is applied to a power shovel.

[0008]

When driving the first hydraulic actuator, the three-way switching valves (claim (c)) and (claim (d)) are operated by an interlocking switching mechanism (claim (e)). 1) is linked to the second port.
Thereby, the two conduits of the first hydraulic actuator communicate with the first outlet and the second outlet of the directional control valve. When the direction control valve is switched in this state, one of the lines of the first hydraulic actuator is on the oil supply side and the other is on the return side, and the other line is on the oil supply side and one is on the return side. Can be switched, and the first hydraulic actuator can be driven back and forth. In any state, any pipeline of the second hydraulic actuator is closed by the three-way switching valve. Here, the hydraulic actuator is a concept including a hydraulic operation mechanism such as a hydraulic cylinder, a hydraulic motor, and a rotary actuator.

When the second hydraulic actuator is operated, each of the three-way switching valves ((c),
(D) The first port is communicated with the third port. Thus, as in the case of the first hydraulic actuator, the second hydraulic actuator can be driven back and forth by switching the direction control valve. Since the three-way switching valve is provided for each pipe, so to speak, the effective inner diameter can be increased and the structure can be simplified.

Further, in the hydraulic circuit according to the first aspect, when the first and second three-way switching valves are switched from the operation state of the first or second hydraulic actuator, the first or second hydraulic switch is temporarily operated. The pipeline of the hydraulic actuator is opened to the drain pipeline. Therefore, the residual pressure when the first or second hydraulic actuator is operating can be released.

Further, the power shovel can open and close the solve bucket using a hydraulic unit for tilting the bucket body. Also, the wrist rotation of the rotating bucket can be performed by using the turning hydraulic unit of the power shovel body. Further, the production cost of the power shovel can be reduced through sharing of the basic part.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The hydraulic circuit, three-way switching valve, interlocking three-way switching valve and power shovel of the present invention will be described below with reference to the drawings. FIG. 1 is a hydraulic circuit showing an embodiment of the hydraulic circuit of the present invention, FIG. 2 is a schematic side view showing an embodiment of the power shovel of the present invention, and FIG. FIG. 4 is a longitudinal sectional view showing an embodiment of the three-way switching valve according to the present invention, and FIG. 5 is a perspective view showing an example of the actual arrangement of the hydraulic circuit shown in FIG.

First, the entire power shovel of the present invention will be described with reference to FIG. Reference numeral 10 in FIG. 2 denotes a vehicle body for moving the power shovel 1 forward or backward, and a body 11 that is rotatable about a vertical axis with respect to the vehicle body 10 is provided at an upper portion of the vehicle body 10. A swingable first arm 20 extends from a front end (left side in FIG. 2) of the main body 11, and a second arm 21 is swingably attached to a distal end of the first arm 20 via a pin 23. These arms 20 and 21 are driven by hydraulic cylinders 24 (two) and 25. The rotating bucket 2 is pivotally connected to the tip of the second arm 21 (at the bottom in FIG. 2) by a shaft 37. The whole rotating bucket is
It is tilted and driven by the first hydraulic cylinder 26 and the link 27. The rotating bucket 2 includes a base 3 directly connected to the second arm 21, and a bucket body 5 connected to the base 3 via a rotary ring 4 so that the wrist can rotate.
And a solve bucket (movable jaw) 7 rotatably connected to the bucket body 5 by pins 6.
The rotating ring 4 has a ring gear, and a so-called wrist rotation can be performed by rotating a pinion gear meshing with the ring gear by a hydraulic motor (not shown). The solve bucket 7 is driven to open and close by a second hydraulic cylinder 8. The hydraulic circuit of the present invention is for switching and operating a first hydraulic cylinder 26 for tilting the bucket body 5 and a second hydraulic cylinder 8 for opening and closing the solve bucket 7, and for turning the power shovel body 11, for example. It is used for switching and operating a hydraulic motor and a hydraulic motor for rotating the entire rotating bucket 2 for wrist rotation.

Next, a hydraulic circuit for switching the first and second hydraulic cylinders 26 and 8 will be described with reference to FIG.
The pipeline 9 on the head side of the first hydraulic cylinder 26 is connected to the second port A2 of the first three-way switching valve A, and the pipeline 12 on the rod side is connected to the second port B2 of the second three-way switching valve B. Have been. The head-side and rod-side conduits 13 and 14 of the second hydraulic cylinder 8 are connected to the third port A3 of the first three-way switching valve A and the third port B3 of the second three-way switching valve B, respectively. I have. The first ports A1 and B1 of the three-way switching valves A and B are respectively connected to the first outlet C1 and the second outlet C2 of the four-way switching valve C having three positions and four ports. The first inlet C of the four-way switching valve C
The third and second inlets C4 are respectively connected to the pump P and the return port of the tank T, respectively. In FIG. 1, F is a filter, H is a check valve, and R is a pilot circuit for switching the four-way switching valve C. Four-way switching valve C
Is preferably a center-closed type. FIG. 1 omits the relief valve from the actual circuit. The first and second three-way switching valves A and B have a common pilot circuit 28, 29 as shown on the left side of FIG. 3, and have a two-position, four-port four-way switching valve (manual switching valve, such as a lever, etc.). )
It is configured to be switched simultaneously by D. That is, such common pilot circuits 28 and 29 are an interlocking switching mechanism of the first aspect. In addition, as the interlocking switching mechanism, in addition to a common pilot circuit, a mechanism that mechanically interlocks with a lever or the like may be used.

In the circuit on the left side of FIG. 3, a line 1 on the head side and a line 14 on the rod side of the second hydraulic cylinder 8 for opening and closing the solve bucket 7 are connected to the line 1 respectively.
3a and 14a are branched. And those pipelines are 2
It is connected to the drain circuit via a solenoid valve SV at position 4 port. The solenoid valve SV is a lever-driven four-way switching valve D
Is operated to switch the state in which the second hydraulic cylinder 8 is driven to the state in which the first hydraulic cylinder 26 is driven, and immediately switch the pipe lines 13a and 14a to "open" so as to connect them to the drain circuit. Instead, the timer returns to the original “closed” (closed state) after a certain period of time. This does not affect the side of the first hydraulic cylinder 26 for driving the bucket body. In FIG. 3, the second
The case where the drain circuit is connected to the hydraulic cylinder side has been described. However, from the same technical idea, even when the drain circuit is connected to the first hydraulic cylinder side, the influence on the second hydraulic cylinder side can be prevented.

On the right side of FIG. 3, a pipe 15 communicating with the hydraulic motor for turning of the main body (11 in FIG. 2) and a pipe 16 communicating with the hydraulic motor for rotating the wrist of the bucket are provided in two three-way directions. Switching is performed by switching valves E and G. 17
Is a double safety unit in which a relief valve 18 and a check valve are combined.
Or when it reaches the left or right turning end. Reference numeral J denotes a pilot four-way switching valve.

Next, the operation of the hydraulic circuit configured as described above will be described. First, a case where the four-way switching valve D for the pilot lines 28 and 29 is not operated will be described with reference to FIG. In this case, the pressure oil from the pump P urges the spools of the three-way switching valves A and B to the right in FIG. Thereby, the first port A1 and the second port A2 of the first three-way switching valve A communicate with each other, and the third port A3 is shut off. At the same time, the first port B1 and the second port B2 of the second three-way switching valve B communicate with each other, and the third port B3 is shut off. Accordingly, the hydraulic cylinder 8 for opening and closing the solve bucket is restrained at that position, and the pipe lines 9 and 12 on the head side and the rod side of the hydraulic cylinder 26 for tilting the bucket body 5 are switched four-way as shown in FIG. It will be connected to valve C. Accordingly, in this state, the four-way switching valve C is connected via the pilot circuit R to the first state in which the first outlet C1 is connected to the pump P from the neutral position (the second outlet C2 is on the tank T side), and the first outlet C1 Is connected to the tank T in the second state (the second exit C2
(Pump side), the bucket body 5 can be freely operated to tilt upward or downward.

Next, the four-way switching valve D for the pilot lines 28 and 29 shown in FIG.
, The spools of the first and second three-way switching valves A and B are simultaneously urged leftward. Thereby, the first ports A1, B1 of the three-way switching valves A, B communicate with the third ports A3, B3 respectively, and the second ports A2, B
2 is shut off. Accordingly, the first hydraulic cylinder 26 for tilting the bucket body 5 is restrained at that position, and the second cylinder 8 for opening and closing the solve bucket 7 is connected to the hydraulic pump P and the tank T via the four-way switching valve C. Thus, the solve bucket can be opened and closed by operating the four-way switching valve C. In the hydraulic circuit diagram of FIG. 1, a circuit in the case where the solve bucket 7 is not provided is indicated by an imaginary line S. That is, in a basic power shovel without the solve bucket 7, the hydraulic cylinder 26 for tilting the bucket body 5 is used.
May be directly connected to the four-way switching valve C. Conversely, when improving a basic excavator with a solve bucket,
A hydraulic circuit unit having two (or four) three-way switching valves and having a hydraulic circuit unit as shown in FIG. 5 may be added, with each actuator (hydraulic cylinder, hydraulic motor, etc.) provided.

Next, an embodiment of the three-way switching valve of the present invention will be described with reference to FIG. This three-way switching valve is particularly preferable as the three-way switching valves A and B in FIGS. In FIG. 4, reference numeral 31 denotes a prismatic body having a cylindrical cavity 32 extending in the axial direction. In the cavity 32, leaving a central portion serving as the valve chamber 33,
Two cylindrical sleeves 34 and 35 are inserted and fixed. The openings at both ends of the body 31 are end caps 3
6,37.

The end caps 36, 37 are formed with holes 38, 39 having pipe tapers for connecting pilot circuits (28, 29 in FIG. 3). Further, a first port 40 communicating with the valve chamber 33 is formed at the center of the body 31. The insides of the two sleeves 34 and 35 communicate with the second port 43 and the third port 44 formed in the body 31 through holes 41 and 42 formed in the sleeves 34 and 35 in the radial direction.

A spool 45 is slidably accommodated in the sleeves 34 and 35 and the valve chamber 33 in the axial direction. At both ends of the spool 45, cylindrical guide portions 46, 47 sliding in the sleeves 34, 35 are provided.
Is provided. The guides 46 and 47 also function as pistons during pilot operation. Spool 45
A cylindrical valve element 48 having an outer diameter larger than the inner diameter of the sleeves 34, 35 is provided at the center of the. And valve body 4
The guide member 8 and the guide portions 46 and 47 are connected by rods 49 and 49. The angle at both ends of the valve body 48 is
0, and their tapered surfaces 50 are
The inner peripheral portions of the opening portions (portions opening toward the valve chamber 33) of the inner portions 4 and 35 are in contact with the corner portions 51 of the inner peripheral edge. That is, the corner portion 51 is a valve seat (seat) that seals between the valve chamber 33 and the inside of the sleeves 34 and 35 when the valve body 48 contacts. In order to play a role of such a valve seat and to guide the spool 45 slidably, each sleeve 34, 35 is made of relatively soft metal such as mild steel, and the spool 45 is made of the sleeve 34, 35.
It is preferable to use harder steel (for example, hardened steel). In FIG. 4, reference numeral 52 denotes a bolt hole for fixing the body 31 to another three-way switching valve and a base plate (55 in FIG. 5), and 53 and 54 denote O-rings for sealing. In the three-way switching valve configured as described above, when the pilot pressure is applied to the pilot connection hole 39 on the right side, the spool 45 moves to the left side as shown in FIG. 4 (solid line arrow). Then, the tapered surface 50 at the left end of the valve body 48 comes into contact with the corner portion 51 of the left sleeve 34, and cuts off communication between the valve chamber 33 and the internal cavity 34a of the left sleeve 34. Thereby, the communication between the first port 40 and the second port 43 is cut off.

On the other hand, the tapered surface 50 at the right end of the valve body 48 is separated from the corner 51 of the right sleeve 35, so that the valve chamber 33 and the internal cavity 35a of the right sleeve 35 communicate with each other, whereby the first The port 40 communicates with the third port 44. Conversely, when the pilot pressure is applied from the pilot connection hole 38 on the left side, the spool 48 moves to the right side as indicated by a broken arrow, and closes the opening of the sleeve 35 on the right side. Thereby, the first port 40 and the third port 43 communicate with each other. As described above, the three-way switching valve of FIG.
Since the tapered surface 50 of the valve body 48 closes the opening facing each other of the cavities 34a and 35a in the 35, there is an advantage that the flow path cross-sectional area at the time of opening can be extremely increased. Therefore, as in the case of the hydraulic circuit of FIG. 1 or FIG. 3, when connected in series with the four-way switching valve C, a pressure drop or the like does not occur, and quick operation of the hydraulic actuator can be secured.

Next, a case where the circuit of FIG. 3 is unitized by using the three-way switching valve of FIG. 4 will be described with reference to FIG.
In the unit shown in FIG. 5, four three-way switching valves A, B, E, and G are mounted in two stages on the front side of a square frame-shaped base plate 55, and four-way switching valves D and J for pilot operation are provided at the other end. Are attached. Furthermore, base plate 55
A double safety unit 17 having two relief valves 18 is attached to the right rear of the vehicle. Thus, the hydraulic circuit for tilting the bucket body 5 and the rotating bucket 2
By unitizing the hydraulic circuit for wrist rotation,
An existing basic type power shovel can be easily modified into a power shovel having a function of opening and closing a solve bucket and rotating a wrist of a rotating bucket. In particular, since two three-way switching valves A, B, E, and G are used as a pair, when they are vertically stacked as shown in FIG. 5, there is an effect of saving space. Further, by using the frame-shaped base plate 55, there is an advantage that piping to the hydraulic unit side can be collected at the center portion and piping to the hydraulic actuator side can be collected outside.

[0024]

[Effect of the Invention] The hydraulic circuit of the present invention is used when adding a new hydraulic actuator to hydraulic equipment such as a power shovel.
There is an advantage that it can be easily added and does not lower the function of existing equipment. Although the power shovel of the present invention has additional functions, it can share parts with the power shovel having basic functions, and can be easily modified from existing power shovels.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of a hydraulic circuit of the present invention.

FIG. 2 is a schematic side view showing one embodiment of the power shovel of the present invention.

FIG. 3 is a hydraulic circuit diagram showing a main part of the hydraulic circuit of FIG. 1 together with a pilot circuit.

FIG. 4 is a longitudinal sectional view showing one embodiment of the three-way switching valve of the present invention.

FIG. 5 is a perspective view showing an example of an actual arrangement of the hydraulic circuit of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Power shovel 2 ... Rotating bucket 5 ... Bucket body 7 ... Solve bucket 8 ... 2nd hydraulic cylinder 10 ... Body 11 ... Main body 26 ... 1st hydraulic cylinder 31 ... Body 33 ... Valve chamber 34, 35 ... Sleeve 40 ... 1st Port 43 Second port 44 Third port 45 Spool 48 Valve element A First three-way switching valve B Second second three-way switching valve

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-127026 (JP, A) JP-A-58-33649 (JP, A) JP-A-61-83728 (JP, A) 206749 (JP, U) Actually open 1987-44956 (JP, U) Actually open 1987-72318 (JP, U) Actually open, 57-3105 (JP, U) Actually open, 1979-79701 (JP, U) Japanese Utility Model Showa 60-14151 (JP, U) Japanese Utility Model Showa 58-98185 (JP, U) Japanese Utility Model Showa 60-16188 (JP, Y2)

Claims (4)

(57) [Scope of request for utility model registration] (A) a plurality of hydraulic actuators which reciprocate by sending pressure oil to one of two pipelines and returning from the other, and (b) a first outlet and a second outlet respectively. A directional control valve selectively and alternately communicating with a pressure oil source or a return pipe; and (c) a first port communicating with a first outlet of the directional control valve, and communicating with one pipeline of a first hydraulic actuator. A first three-way switching valve having a second port and a third port communicating with one of the pipelines of the second hydraulic actuator, and selectively communicating the first port with the second port or the third port; d) a first port communicating with the second outlet of the directional control valve, a second port communicating with the other pipeline of the first hydraulic actuator, and a third port communicating with the other pipeline of the second hydraulic actuator. And the first port (E) an interlocking switching mechanism for switching the first three-way switching valve and the second three-way switching valve while synchronizing the first three-way switching valve and the second three-way switching valve. (F) one of the first and second hydraulic actuators has a branch pipe connected to a drain pipe via an on-off valve, and one pipe and the other pipe have a branch pipe. The first
And a hydraulic circuit such as a power shovel configured such that when the second three-way switching valve is switched to operate the first or second hydraulic actuator, the on-off valve is opened for a predetermined time. 2. A first hydraulic cylinder for tilting a bucket body, a second hydraulic cylinder for opening and closing a solve bucket, and a first hydraulic cylinder for turning a power shovel body. (D) a second hydraulic motor for wrist-rotating the rotating bucket; (e) a hydraulic circuit for alternately using the first hydraulic cylinder and the second hydraulic cylinder for use; The hydraulic circuit for a power shovel or the like according to claim 1, further comprising: f) a hydraulic circuit for alternately using the first hydraulic motor and the second hydraulic motor. 3. The hydraulic circuit according to claim 2 , wherein when adding a separate function to an existing hydraulic drive mechanism such as a power shovel, the hydraulic circuit is added to the existing hydraulic circuit. Hydraulic circuit for wrist rotation of rotating bucket and additional hydraulic circuit unit. 4. A power shovel having the hydraulic circuit according to claim 1.