JP2526813Y2 - Compound control valve - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite control valve used for civil engineering construction machines and the like, and more particularly to a composite control valve capable of minimizing a natural fall due to the weight of an actuator and a load raised and lowered by the actuator. .

[0002]

2. Description of the Related Art As shown in FIG. 5, a composite control valve 10 of this type generally has a plurality of directional control valves (four in this embodiment) 14, 16, 18, and 20 arranged in parallel in a casing 12 thereof. The directional control valve is provided with each supply / discharge port 22a,
Actuators are connected to 22b... 28a and 28b, respectively. In the figure, only one actuator 34 connected to the second direction switching valve 16 from the bottom in the figure via the pipes 32a and 32b is shown. In such a configuration, the discharge oil from the pump 30 flows into the pressure oil inflow port 36, and passes through a center bypass oil passage (not shown) when the direction switching valves 14 to 20 are in a neutral state. The oil is discharged from the pressure oil outflow port 37 to the tank 38. For example, when the directional control valve 16 is operated to the left in the figure, the discharge oil from the pump is supplied to the supply / discharge port 2
4a flows into the piston rod side oil chamber 34a of the actuator 34 via the pipe 32a to operate the load W, while the oil in the piston head side oil chamber 34b is supplied via the pipe 32b to the supply / discharge port 24b and the pressure oil flows out. It is configured to flow out of the tank 37 through the port 37.

By the way, in such a construction machine,
When the actuator 34 is, for example, an actuator for a power shovel or the like, since the directional control valve generally has a certain predetermined amount of internal leakage, the actuator 34 and the load W naturally drop, causing a safety problem. Therefore, in this type of composite control valve, a drift reduction valve 40 for preventing backflow of oil from the piston rod side oil chamber 34a of the actuator 34 with respect to the specific direction switching valve 16 is indicated by a two-dot chain line. And is provided on the pipe 32a to prevent the natural descent. Reference numeral 42 denotes an accessory valve for overload relief or anticavitation for the direction switching valve 16, but when the drift reduction valve 40 is provided as described above, the accessory valve 42 is also attached to the valve. For operational relevance, it is located between the drift reduction valve 40 and the actuator 34 as shown by the two-dot chain line.

[0004]

However, in the above-mentioned prior art, the drift reduction valve and the accessory valve are provided on the external piping, so that a considerable space is required and the accessory casing and the drain piping are required.
It had the drawback of increasing costs. Further, when the piping distance between the directional control valve and the drift reduction valve is long, there is a disadvantage that an instantaneous drop of the actuator and load occurs when the drift reduction valve is released due to the compressibility of the fluid and the expansion of the piping. Had.

Accordingly, an object of the present invention is to eliminate the unnecessary space and equipment and to reduce the drift by constructing the drift reduction valve so that it can be disposed close to the directional control valve in the casing of the composite control valve. An object of the present invention is to provide a composite control valve capable of preventing an instantaneous drop of an actuator and a load generated when the valve is released.

[0006]

In order to achieve the above object, a composite control valve according to the present invention comprises a plurality of directional control valves arranged in parallel in a casing in order from the upstream side to the downstream side of the pressure oil supply. In the combined control valve, a specific directional switching valve that requires an extremely small internal leakage amount of the pressure oil and one supply / discharge port of the upstream or downstream directional switching valve adjacent to the specific directional switching valve are sequentially arranged, respectively. A casing inner core which is deviated to an upstream or downstream position and is connected to a supply / discharge port at an upper portion of the specific direction switching valve, and activates or releases a backflow prevention function of the pressure oil in the casing inner core. The invention is characterized in that a pilot pressure operated drift reduction valve is provided.

[0007]

According to the composite control valve of the present invention, the drift reduction valve is provided in the casing inner core connected to the supply / discharge port of the directional control valve. That is, it is configured to be disposed close to the direction switching valve in the casing of the composite control valve. The drift reduction valve and the direction switching valve are connected by a passage inside the casing, and a drain pipe is also connected inside the casing.

As described above, according to the composite control valve of the present invention, unnecessary space and equipment outside the casing for installing the drift reduction valve are eliminated, and momentary movement of the actuator and load when the drift reduction valve is released. Descent is also prevented.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a composite control valve according to an embodiment of the present invention; In addition,
For convenience of description, the same components as those of the conventional structure shown in FIG. 5 are denoted by the same reference numerals, and detailed description thereof will be omitted.

First, the embodiment shown in FIGS. 1 to 4 is one in which the technology according to the present invention is applied to the conventional composite control valve shown in FIG. Accordingly, since the two components have the same basic configuration, this will be briefly described below. The composite control valve 10 includes four directional control valves 14, 16, 18, and 20 disposed in parallel in the casing 12. And supply / discharge ports 22a, 22b... 28 of these directional control valves.
An actuator is connected to each of a and 28b.
Here, the directional control valve 16 is a specific directional control valve that needs to make the internal leakage amount particularly small with respect to the flow of the pressure oil from the pump 30 flowing in from the pressure oil inflow port 36. 1 shows only the actuator 34 connected to the supply / discharge ports 24a, 24b of the specific direction switching valve 16 via the pipes 32a, 32b. Next, the flow of the pressurized oil will be described mainly with reference to FIGS.
Is in a neutral state, the discharge oil from the pump 30 is discharged from the pressure oil inflow port 36 to the tank 38 via the center bypass passage 56 and the pressure oil outflow port 37. next,
For example, when the spool 58 of the specific direction switching valve 16 is operated to the left in the drawing, at this time, the center bypass passage 56
Is closed, the discharge oil from the pump 30 is supplied from the supply oil passage 60 to the supply / discharge oil passage 62 which is operated in communication therewith.
a through the supply / discharge port 24a and the pipe 32a to flow into the piston rod side oil chamber 34a of the actuator 34 to increase the load W, while the piston head side oil chamber 34b
The oil inside the pipe 32b, the supply / discharge port 24b, the supply / discharge oil passage 62
b, It passes through the tank oil passage 64 and flows out of the pressure oil outflow port 37 to the tank 38. Next, when the spool 58 is operated to the right in the drawing, the discharge oil from the pump 30 passes from the supply oil passage 60 through the supply / discharge oil passage 62b that is operated in communication with the supply oil passage 60, and the supply / discharge port. 24b, piping 32b
Through the piston head side oil chamber 3 of the actuator 34
The oil in the piston rod side oil chamber 34a flows through the pipe 32a, the supply / discharge port 24a, the supply / discharge oil passage 62a, the tank oil passage 64, and flows out of the pressure oil outflow port 37. It flows out to the tank 38.

However, in the composite control valve of the present invention, the pilot pressure-operated drift reduction valve 5 for operating or canceling the fluid backflow prevention function for the specific direction switching valve 16 is provided.
0 is one supply / discharge port of the specific direction switching valve 16, that is, a piston rod side oil chamber 34a of the actuator 34.
And is connected to the specific direction switching valve 16 by a casing internal passage 54 while being provided in a casing internal core 52 connected to the supply / discharge port 24a on the side connected to the port. In order to configure the internal core 52, one of the supply / discharge ports 24a and 22a of the specific direction switching valve 16 and the upstream direction switching valve 14 adjacent thereto is provided.
It is sequentially shifted to the upstream position.

The drift reduction valve 50 has an internal core 52
And a control unit 50b for controlling the main poppet 50a. The controller 50b is operated by the pilot pressure, and when the spool 58 of the specific direction switching valve 16 is operated to the left in the drawing, this operation connects the supply / discharge oil passage 62b and the tank oil passage 64. When the spool 58 is operated rightward in the drawing immediately before the operation, the lock of the main poppet 50a is released immediately before the supply / discharge oil passage 62a and the tank oil passage 64 are connected by this operation. like,
That is, the backflow prevention function is released. In the neutral state of the spool 58, the main poppet 50a is locked, that is, the backflow prevention function is activated. The accessory valve 42 is a specific direction switching valve 1
6 and the drift reduction valve 50, so as to operate properly regardless of the arrangement of the drift reduction valve 50, and the drain pipe of the drift reduction valve 50 It is connected to the oil passage 64 so that no special external piping is required.

Therefore, according to the composite control valve of the present invention having such a structure, when the spool 58 of the specific direction switching valve 16 is operated to the left in the drawing, as described above, the supply and discharge oil passage 62b is provided. Immediately before the connection with the tank oil passage 64, the backflow prevention function of the drift reduction valve 50 is released, so that the oil discharged from the pump 30 pushes up the drift reduction valve 50 (main poppet 50a) in the supply / discharge oil passage 62a. And flows into the piston rod side oil chamber 34a to increase the load W, while the oil in the piston head side oil chamber 34b passes through the supply / drain oil passage 62b
Flowed out to 8. When the spool 58 is operated to the right in the drawing, the drift reduction valve 5 immediately before the supply / discharge oil passage 62a and the tank oil passage 64 are connected as described above.
0 is released, the oil discharged from the pump 30 is supplied from the oil supply / discharge oil passage 62b to the piston head side oil chamber 34.
b, the load W falls, while the oil in the piston rod side oil chamber 34a flows in the supply / discharge oil passage 62a without being blocked by the drift reduction valve 50, and flows into the tank oil passage 64.
From the tank to the tank. However, the spool 58
Is in the neutral state, the backflow prevention function of the drift reduction valve 50 is activated as described above, so that the backflow of the oil in the piston rod side oil chamber 34a to the specific direction switching valve 16 is prevented, The natural fall of the load W is prevented. Furthermore, since the drift reduction valve 50 and the direction switching valve 16 are connected to each other via the casing internal passage 54 in an extremely short manner, the instantaneous spontaneous drop of the load W when the backflow prevention function of the drift reduction valve 50 is released. Is also prevented.

As described above, according to the composite control valve of the present invention, the drift reduction valve can be disposed in the casing without rearranging other accessory valves, so that the entire composite control valve is converted. It can be provided at low cost. In addition, it is possible to prevent instantaneous natural drop of the load at the time of canceling the backflow prevention function of the drift reduction valve, which is often generated in the related art, thereby further improving safety. In the present embodiment, the case where the specific direction switching valve is disposed at the second position from the upstream side has been described, but the position is another position, for example, the second position from the most upstream side or the downstream side. Obviously, in this case, in the former case, only one of the supply / discharge ports on the most upstream side is moved upstream, and in the latter case, the one of the most downstream / second supply / discharge port is placed on the upstream side. It is easily understood that each of them is shifted to the downstream side.

Although the present invention has been described with reference to the preferred embodiment, the present invention is not limited to the above-described embodiment, and many design changes can be made without departing from the spirit of the present invention.

[0016]

As described above, the composite control valve of the present invention activates or cancels the fluid backflow prevention function for a specific directional control valve that needs to minimize the internal leakage of the fluid. The pilot pressure actuated drift reducing valve is arranged in the casing inner core connected to one of the supply / discharge ports of the specific direction switching valve, so that the actuator operated by the specific direction switching valve and the actuator The natural descent by the weight of the load to be raised and lowered can be reliably achieved without increasing the structure of the entire composite control valve. Furthermore, as a result of the drift reduction valve being disposed at an extremely short position with respect to the specific direction switching valve,
Momentary spontaneous natural drop of the load at the time of releasing the backflow prevention function of the drift reduction valve, which has often been generated in the past, is also prevented, and safety can be further improved. The drift reduction valve is installed without rearranging the auxiliary valve for overload relief or anticavitation, etc., so that the function of the auxiliary valve is not impaired, and the overall structure of the composite control valve is compact. And can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of a composite control valve according to the present invention.

FIG. 2 is a cross-sectional plan view of FIG.

FIG. 3 is a sectional view taken along line III-III of FIG.

FIG. 4 is a sectional view taken along the line IV-IV of FIG. 1;

FIG. 5 is a plan view showing a conventional composite control valve.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Composite control valve 12 ... Casing 14, 18, 20 ... Direction switching valve 1
6. Specific direction switching valve 20a, 20b-28a, 28b ... Supply / discharge port 3
0 ... Pump 32a, 32b ... Piping 34 ... Actuator 34a ... Piston rod side oil chamber 34b ... Piston head side oil chamber 3
6 ... Pressure oil inflow port 37 ... Pressure oil outflow port 38 ... Tank 4
2, 44 ... Attached valve 50 ... Drift reduction valve 50a ... Main poppet 50b ... Control unit 52 ... Inner core 5
4: Casing internal passage 56: Center bypass passage 5
8. Spool 60 ... Supply oil passage 62a, 62b ... Supply / drain oil passage 64 ... Tank oil passage

Claims (1)

(57) [Scope of request for utility model registration] In a composite control valve in which a plurality of directional control valves are sequentially arranged in parallel in a casing from an upstream side to a downstream side of a pressure oil supply, it is necessary to minimize the internal leakage of the pressure oil. One supply / discharge port of a specific directional control valve and one of the upstream and downstream directional control valves adjacent to the specific directional control valve are sequentially shifted to upstream or downstream positions, respectively. A composite control valve, comprising: a casing inner core connected to an exhaust port; and a pilot pressure operated drift reduction valve for operating or canceling a backflow prevention function of pressure oil is provided in the casing inner core. .