JP3511297B2 - Directional switching valve with lock valve - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lock valve having a directional control valve for supplying and discharging pressurized oil to and from a drive cylinder of a boom or an arm of a construction machine. The present invention relates to a directional control valve. 2. Description of the Related Art A directional control valve for supplying and discharging pressure oil to and from a hydraulic cylinder used for driving a boom or an arm of a construction machine is left in a stopped state for a long time with the boom or the arm raised. Then, the hydraulic pressure generated in the hydraulic cylinder due to the weight of the boom or the arm or the weight and the load continues to act on the load port of the directional switching valve connected to the hydraulic cylinder. Oil leaks due to the minute gap between the boom and the arm, causing the boom and the arm to gradually descend. In order to prevent this, a lock valve is conventionally provided on the way to the direction switching valve of the passage discharged from the hydraulic cylinder at the time of the load reduction operation. The configuration is shown in FIG. In the figure, 1 is a direction switching valve, 2 is a remote control valve, 3 is a pilot valve, 4 is a lock valve, and 5 is a hydraulic cylinder for an arm. Although the pilot valve 3 and the lock valve 4 are shown separately in the drawing, these are integrally formed in a commercially available product. If the remote control valve 2 is operated in the load increasing direction from the neutral position, a hydraulic pilot signal is given to the pilot portion 6 of the direction switching valve 1 to be switched to the switching position 1a, and the hydraulic oil from the pump P is locked. The valve 4 is opened against the valve spring 7 and is supplied to the hydraulic chamber 5a of the hydraulic cylinder 5, and the hydraulic cylinder 5 operates in the load increasing direction. When the remote control valve 2 is returned to the neutral position, the switching valve 1 also returns to the neutral position, the supply of the pressure oil from the pump P is cut off by the switching valve 1, and the passage 8 between the switching valve 1 and the hydraulic chamber 5a is closed. It is shut off by the lock valve 4. In this load increasing state, the load W is acting and the hydraulic pressure is generated in the hydraulic chamber 5a. However, even if the load W is left for a long time, the arm does not gradually descend due to the presence of the lock valve 4. When the remote control valve 2 is operated in the load decreasing direction from the state where the arm is raised as described above, the hydraulic pilot signal is given to the pilot portion 9 of the direction switching valve 1 and is switched to the switching position 1b. Since the hydraulic oil from the pump P is supplied to the hydraulic chamber 5b of the hydraulic cylinder 5, and the same hydraulic pilot signal is also given to the pilot valve 3 to open the pilot passage 10, the back pressure chamber 4a of the lock valve 4 Hydraulic pressure is pilot passage 10, pilot valve 3
Through the tank T. Therefore, the pressure oil in the hydraulic chamber 5a passes through the passage 8, pushes and opens the lock valve 4 and is discharged from the direction switching valve 1 to the tank T, and the hydraulic cylinder 5 operates in the load decreasing direction. A lock valve 4 attached to the directional control valve 1 for supplying and discharging pressure oil to and from the hydraulic cylinder 5 for the arm described above is a hydraulic pilot signal supplied to the directional control valve 1. Since the lock is released by opening the pilot valve 3 by the same hydraulic pilot signal as the above, the opening operation of the direction switching valve 1 and the unlocking of the lock valve 4 (opening operation of the pilot valve 3) are temporarily performed. It is going to be done at the same time. However, there is no guarantee that the lock will be released at the same time without delaying the opening of the directional control valve 1. In reality, a slight impact may occur at the start of the operation of the hydraulic cylinder 5 in the unloading direction. This is caused by the opening operation of the directional control valve 1 caused by the lock valve 4 for some reason.
It is considered that the lock release operation of is sometimes delayed. Further, this type of directional control valve 1 is connected and fixed in a block shape integral with several other directional control valves,
It is fixed to a part of an industrial machine, and it is desired that the dimension in the connection direction be as small as possible in order to reduce the size of the entire machine. The lock valve 4 and the pilot valve 3 described above are originally desirably formed in the main body of the directional control valve 1. However, since the connecting direction dimensions of the directional control valve 1 cannot be increased, they cannot be easily formed. The switching valve 1 is configured to be connected to a proper position of the main body or to be provided at another position. Therefore, the lock valve 4 and the pilot valve 3 are provided and the pilot passage 11 from the remote control valve 2 is lengthened by the provision of the lock valve 4 and the pilot valve 3, which goes against miniaturization. SUMMARY OF THE INVENTION It is an object of the present invention to provide a directional control valve with a lock valve that is slightly earlier than the opening operation of the directional control valve in releasing the lock valve, and is also suited for miniaturization. I do. According to the present invention, there is provided a lock valve having an axis parallel to a spool of a directional control valve, wherein the lock valve has the directional control valve, each of which is arranged on the same axis. A main valve that opens and closes a load port of the valve, a small valve that opens and closes a back pressure chamber of the main valve, and a pilot piston that presses the small valve. The pilot piston connects the pilot chamber to the direction switching valve. A pilot passage opening / closing portion is provided on the spool of the directional control valve so as to release the pressing force of the small valve connected to the pilot source prior to opening the valve at the time of the load reduction operation, and the pilot valve is moved with the movement of the spool.
To open and close the load passage opening and closing the load port.
It is characterized by connecting to the network . The main valve of the lock valve is unlocked by releasing the pressing force of the pilot piston pressing the small valve, thereby opening the back pressure chamber of the main valve. When the directional control valve is operated to supply the pressure oil in the load reduction direction, the lock state of the lock valve is released, and then the directional control valve is opened. This order is ensured by providing the pilot passage opening / closing portion on the spool of the directional control valve. Therefore,
The timing at which the lock state of the lock valve is released is surely slightly earlier than the opening operation of the direction switching valve. Further, by providing the spool of the directional control valve and the axis of the lock valve in parallel, the main body of the directional control valve can be connected without increasing the size of the main body of the directional control valve in the connection direction with other directional control valves. Most of the lock valve can be incorporated in the inside, and since the pilot oil pressure of the pilot piston can be an on / off signal, there is no need to use the pilot oil pressure signal from the remote control valve.
A pilot hydraulic pressure signal can be obtained by using a pilot source pressure of 0 to 40 kg / cm ² ) and a pilot passage opening / closing portion added to a spool of the directional control valve located near the lock valve. Is possible. An embodiment of the present invention will be described with reference to FIGS. This embodiment is a directional control valve 21 with a lock valve for a hydraulic cylinder 20 for a boom. This directional control valve 2
1 is a normal one comprising a main body 22, a spool 23, etc.
The lock valve 24 is additionally provided. The main body 22 is provided with an inner hole 25 into which the spool 23 is inserted, and the inner hole 25 has an enlarged inner hole portion (hereinafter, simply referred to as an enlarged portion) 26, 27, 28, 29, 30, 3.
1, 32, 33, 34, 35, 36 are formed.
A passage 37 is formed following the enlarged portion 26.
Subsequently, a load port 38 opened on the outer surface of the main body 22 is provided. One end of a bridge passage 39 is connected to the enlarged portion 27, and a main passage 40 connected to a pump port is connected to the middle of the bridge passage 39 via a load check valve 41. The enlarged portions 28 and 30 are connected to the main passage 40 via a passage (not shown). Enlargement part 2
Reference numeral 9 is connected to the tank via a passage (not shown). The other end of the bridge passage 39 is connected to the enlarged portion 31. A passage 43 is formed following the enlarged portion 32, and a load port 44 opened on the outer surface of the main body 22 is provided following the passage 43. A lock valve 24 described later is provided in the middle of the passage 43. A passage 45 is connected to the enlarged portion 33, and this passage 45 is connected to the tank via a passage (not shown). And this passage 45
Is connected to the enlarged portion 32 via an overload relief valve 46 and a passage 47. The enlarged portion 34 is connected to a pilot hydraulic pressure source via a passage 48, and the enlarged portion 35 is connected to the pilot passage 4.
9 to the pilot chamber 81 of the lock valve 24,
The enlarged portion 36 is connected to the tank via a drain passage (not shown). The spool 23 is inserted into the inner hole 25 of the main body 22 and provided with hydraulic pilot chambers 51 and 52 at both ends, and a remote control valve (pilot valve), not shown, respectively.
The pilot passage from is connected. Spool 23
Are held in a fixed position (neutral position) without a pilot signal in the hydraulic pilot chambers 51 and 52 on both sides,
A holding spring 53 is provided at the end on the pilot chamber 52 side. The spool 23 is provided with annular grooves 54, 55, 56, 57 and longitudinal grooves 58, 59 in the axial direction of the spool in relation to the enlarged portions 26 to 36 of the inner hole 25 of the main body 22. Some of these annular grooves are provided with notches for controlling the flow rate, but the details regarding the notches are omitted because they are detailed. The annular groove 54 allows the enlarged portions 26 and 27 to communicate with each other when the spool 23 is moved beyond the predetermined dimension e1 rightward from the neutral position shown in the figure. The annular grooves 55, 56 communicate with the enlarged portions 28, 29, 30 when the spool 23 is in the neutral position, and when the spool 23 is moved to the right or left in the drawing beyond the predetermined dimension e5, Each of the enlarged portions 28, 29, 30 is shut off. The annular groove 57 allows the enlarged portions 31 and 32 to communicate with each other when the spool 23 is moved to the left from the illustrated neutral position beyond the predetermined dimension e2, and extends beyond the specified dimension e3 to the right from the illustrated neutral position. When moved, the enlarged portions 32 and 33 communicate with each other. The vertical groove 58 is provided as a pilot passage opening / closing portion of the lock valve 24. When the spool 23 is moved from the neutral position in the figure to the right over a predetermined dimension e4, the enlarged portions 34 and 35 are formed. It is to communicate. The vertical groove 59 communicates with the enlarged portions 35 and 36 when the spool 23 is in the illustrated neutral position, and shuts off between the enlarged portions 35 and 36 when slightly moved rightward from the neutral position. On further movement, it remains blocked,
Enlarged section 35 when moved to the left from the neutral position
And 36 remain in communication. E5 is smaller than the predetermined dimensions e1 and e3, and e4 is smaller than the predetermined dimension e5. The connection order of the respective enlarged portions when the spool 23 moves rightward is determined. I have decided. The lock valve 24 is composed of a main valve 61, a small valve 62, a pilot piston 63, and the like, which are sequentially arranged on the same axis, so that the axis is parallel to the upper side of the spool 23 in the figure. It is provided in. The cross section in the figure is a cross section perpendicular to the connecting direction of the directional switching valve 21 with the lock valve and another directional switching valve arranged adjacent thereto, and the direction perpendicular to the paper surface is the connecting direction. The thickness of the main body 22 in the connection direction is formed as thin as possible. Although not shown, the thickness is substantially equivalent to the outer shape of the pilot portion at both ends of the spool 23. A lock valve 24 is provided in the main body 22 by forming an inner hole 64 reaching the passage 43. The lock valve 24 of FIG. 1 and its vicinity are shown in an enlarged scale in FIG. The main valve 61 is capable of moving back and forth along an inner hole 64, and is pressed by a main valve spring 66 on a valve seat 65 forming a valve hole formed in the middle of the passage 43, so that the valve hole, that is, the passage is formed. 43 is closed. The inner diameter of the valve hole is Ri Thea formed smaller than the inner diameter of the inner hole 64, the pilot piston 6
In the state where the pilot pressure described later does not act on 3,
Is are to produce the closing force acting on the main valve 61 by the pressure of the load port 44 side. When the main valve 61 is closed, there is a communication having a throttle 68 between the back pressure chamber 67 of the main valve in which the main valve spring 66 is housed and a portion of the closed passage 43 communicating with the load port 44 side. A hole 69 is formed in the main valve 61. A small valve 62 is disposed behind the main valve 61 and on the right side in the figure. The small valve 62 is a sphere, and forms a valve seat 72 at the rear end of a communication hole 71 formed in the spring receiving / valve seat member 70 of the main valve spring 66 so as to penetrate in the axial direction. Valve seat 72
To the communication hole 7
1 is closed. At the rear end of the member 70, a member 90 is screwed by a screw portion 73.
A valve chamber 74 is formed so as to hold the valve 2 so as to be able to open and close. The valve chamber 74 is connected by a passage 83 to the side where the passage 43 is connected to the enlarged portion 32, that is, to the front side of the main valve 61. The member 90 fits into the inner hole 64 and the screw portion 75
The member 70 is also fixed to the main body 22 by this. At the rear of the member 90, an inner hole 76 in which the pilot piston 63 is accommodated and slides in the front-rear direction is formed, and the small valve pressing projection 77 of the pilot piston 63 extends across the inner hole 76 and the valve chamber 74. Is formed. The pilot piston 63 is accommodated in the inner hole 76 and has a small valve pressing projection 77 protruding from the front end surface. The pilot piston 63 is pressed by a spring 79 from the back surface, and the tip of the projection 77 presses the small valve 62. It has become. The rear end of the spring 79 is fixed to the body 22 and is supported by a member 80 surrounding the rear of the member 90 . The front end of the inner hole 76 accommodating the pilot piston 63 is located in the pilot chamber 8.
The pilot chamber 81 is provided with the pilot passage 49 communicating with the enlarged portion 35. The spring chamber 84 containing the spring 79 is connected to the tank via a drain passage 85. Reference numeral 86 in the figure fixes the member 80 to the main body 22 with bolts. The illustrated state of the lock valve 24 is a locked state. That is, the main valve 61 is seated on the valve seat 65,
The small valve 62 is pressed by the pilot piston 63 and the valve seat 7
2 is seated. In order to open the main valve 61 in this locked state, it is necessary that the pressure on the load port 44 side rises and the small valve 62 pushes the pilot piston 63 against the spring 79 by the pressure. The spring 79 is set so that the small valve 62 opens when the oil pressure on the load port 44 side rises to a pressure slightly lower than the set pressure of the overload relief valve 46. Therefore, when the oil pressure on the load port 44 side becomes higher than the set pressure of the overload relief valve 46, the small valve 62 opens, the main valve 61 opens, and the overload relief valve 46 also opens. ing. The lock release of the lock valve 24 is
This is performed by the pilot oil pressure acting on the pilot chamber 81. That is, when the pilot piston 63 retreats against the spring 79 by the pilot oil pressure, the small valve 62 is released from the pressing force and is opened, and the lock is released. In this unlocked state, when the front side of the main valve 61, that is, the passage 43 communicating with the enlarged portion 32 is connected to the tank, the hydraulic pressure of the back pressure chamber 67 also decreases, and the main valve 61 is connected to the inner hole 64 and the valve. The valve is easily opened by the hydraulic pressure on the load port 44 side acting on the area difference portion of the valve hole of the seat 65. In the directional control valve 21 with the lock valve configured as described above, the load port 38 is connected to the load-lowering-side pressure chamber 20a of the boom hydraulic cylinder 20, and the load port 44 is connected to the load-up-side pressure chamber 20b. Used. The directional control valve 21 is operated by operating the remote control valve.
When the pilot pressure acts on the hydraulic pilot chamber 52 of
The spool 23 moves leftward from the illustrated neutral position.
When the spool 23 is moved to the left, the enlarged portion 2
8 and 30 and the enlarged portion 29 are closed by the land portion of the spool, the hydraulic pressure of the main passage 40 rises, and the enlarged portions 31 and 57 are opened, so that the pressure oil flows from the main passage 40 to the load check valve 41. Is pushed open to pass through the bridge passage 39 and reach the passage 43. And the pressure oil is
Further, the main valve 61 of the lock valve 24 is pushed open against the main valve spring 66, reaches the load pushing-side pressure chamber 20 b of the boom hydraulic cylinder 20 through the load port 44, and pushes up the load. That is, the boom tip rises. In this state, the remote control valve is returned to the neutral position and the hydraulic pilot chamber 52
When the oil pressure signal is no longer present, the spool 23 returns to the illustrated neutral position. This state is a state in which a load is applied to the hydraulic cylinder 20, and the hydraulic pressure due to the load is applied to the load port 44. However, the lock valve 24 is provided in the middle of the passage 43 following the load port and is closed. So
There is no outflow of pressurized oil from the load lifting side pressure chamber 20b of the hydraulic cylinder 20, and the boom does not descend even if left for a long time. When the pilot pressure acts on the hydraulic pilot chamber 51 of the direction switching valve 21 by the reverse operation of the remote control valve, the spool 23 moves rightward from the neutral position shown in the figure. When the spool 23 is moved to the right, the enlarged portions 34 and 35 are first communicated with each other by the vertical groove 58 in accordance with the dimensional differences of the predetermined dimensions e1, e3, e4, and the like. Part 34
Pressure oil from a pilot source reaching 40 kg / cm ²
Is supplied to the pilot chamber 81 of the lock valve 24 through the pilot passage 49. With this pressure oil, the pilot piston 63 is retracted against the spring 79, and the pressing of the small valve 62 is released. As a result, the back pressure chamber 67 of the main valve 61
Is provided with a communication hole 71 on the side connected to the enlarged portion 32 of the passage 43,
The communication between the valve chamber 74 and the passage 83 is established, and this state is the unlocked state of the lock valve 24. Next, the space between the enlarged portions 28 and 30 and the enlarged portion 29 is closed by the land portion of the spool, and the hydraulic pressure of the main passage 40 rises. Next, the enlarged portions 26 and 27 are communicated by the annular groove 54, and at the same time, the enlarged portions 32 and 33 are communicated by the annular groove 57. Therefore, the pressure oil in the main passage 40 pushes and opens the load check valve 41, passes through the bridge passage 39, the enlarged portions 27 and 26, the passage 37, and the load port 38, and is supplied to the load depressing-side pressure chamber 20a of the hydraulic cylinder 20. Is done. At this time, the oil in the load boosting side pressure chamber 20b is pushed out, and
4, the main valve 61 of the lock valve 24 unlocked at the end of the passage 43 is pushed open to pass through the enlarged portions 32 and 33,
Since the hydraulic cylinder 20 is discharged into the tank, the hydraulic cylinder 20 performs a load lowering operation. When the remote control valve is returned to the neutral position during the load pressing operation and the hydraulic pilot signal in the hydraulic pilot chamber 51 is lost, the spool 23 returns to the neutral position, and the operation of the hydraulic cylinder 20 stops. In this process, first, the space between the enlarged portions 26 and 27 is shut off, and at the same time, the enlarged portions 32 and 3
3, the supply of the pressure oil from the main passage 40 to the load pushing-down pressure chamber 20a stops, and the discharge of the oil from the load pushing-up pressure chamber 20b to the tank stops. As a result, the load check valve 41 is closed, and the main valve 61 is closed by the pressing force of the main valve spring 66. Next, the enlarged portions 28 and 3
0 and opening between the enlarged portion 29, the pressure oil of the main passage 40 is to flow into the tank, the oil pressure of the main passage 40 is reduced. Next, the space between the enlarged portions 34 and 35 is shut off. Subsequently, the space between the enlarged portions 35 and 36 is connected by the vertical groove 59, and the spool 23 returns to the neutral position. As a result, the pilot signal from the pilot source to the pilot chamber 81 disappears, and the pilot piston 63
The small valve 62 is pressed against the valve seat 72 to close the passage 71 and the lock valve 24 is locked. When the lock valve 24 is in the locked state as described above, the pressure oil on the load port 44 side connected to the load boosting side hydraulic chamber 20b of the hydraulic cylinder 20 at the main valve 61 does not leak to the tank side. There is no such thing, and even if left as it is for a long time, the tip of the boom does not gradually descend. According to the present invention, when the directional control valve is operated to supply the pressure oil in the load reduction direction, the lock state of the lock valve is released, and then the directional control valve is opened. I do. Since this sequence is ensured by providing the pilot passage opening / closing portion on the spool of the directional control valve, the timing at which the lock state of the lock valve is released is slightly earlier than the opening operation of the directional control valve. Therefore, it is possible to reliably prevent the occurrence of an impact due to a delay in the timing of opening the lock valve. Further, by providing the spool of the directional control valve and the axis of the lock valve in parallel, the main body of the directional control valve can be connected without increasing the size of the main body of the directional control valve in the connection direction with other directional control valves. Most of the lock valve can be incorporated therein, which is effective for miniaturization.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional front view showing one embodiment of the present invention. FIG. 2 is a partially enlarged view of FIG. FIG. 3 is a schematic view showing a configuration of a conventional directional control valve provided with a lock valve. [Description of Signs] 21 Directional switching valve with lock valve 23 Spool 24 Lock valve 58 Vertical groove (pilot passage opening / closing portion) 61 Main valve 62 Small valve 63 Pilot piston 81 Pilot chamber

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Megumi Miyake 4-2-27 Nagasawacho, Hyogo-ku, Kobe-shi, Hyogo Prefecture Heights Nagasawa 404 (72) Inventor Shoichi Maeda 2- 14-11 Aioi, Aioi-shi, Hyogo (56) References JP-A-54-123416 (JP, A) JP-A-50-121949 (JP, A) JP-A-63-74899 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name ) F15B 11/08 E02F 9/22

Claims (1)

(57) Claims 1. A lock valve is provided with an axis parallel to a spool of a directional control valve, and the lock valve is provided with a directional control valve which is disposed on the same axis. It comprises a main valve for opening and closing a load port, a small valve for opening and closing a back pressure chamber of the main valve, and a pilot piston for pressing the small valve. The pilot piston lowers the load in the pilot chamber by the directional control valve. prior to opening during operation is connected to the pilot source provided the pilot channel opening and closing portion to the spool of the directional control valve so as to release the pressing force of the small valve, the spool
Communicates with the pilot passage opening / closing section as the tool moves,
A directional switching valve with a lock valve, wherein the load port is connected to a tank .