JPH0638925Y2 - Hydraulic control valve device for shovel loader - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a boom cylinder for excavating a boom in a shovel loader or the like that adjusts the ground to the irregularities of the boom in order to move the boom up and down in accordance with the irregularities of the ground. Both oil supply oil passages are connected to the tank at the same time, that is, the hydraulic control valve device in which the boom cylinder has a floating function. More specifically, both oil supply oil passages are connected to the tank at the same time. The present invention relates to improvement of a logic valve used for communication.

[Conventional technology]

Conventionally, as shown in FIG. 3, this type of hydraulic control valve device basically controls the direction of the boom cylinder 12 driven by the discharge oil of the main pump 10 and other, for example, bucket cylinder 14. Main multi-valve valve body 20 having two unit valves 16 and 18, and two pilot valves 22 and 22 for controlling the direction of the discharge oil of the pilot pump 21 for operating the two unit valves 16 and 18, respectively. It is composed of a pilot multi-valve valve body 26 having 24. And, between the unit valve 16 and the pilot valve 22, and between the unit valve 18 and the pilot valve 24, the ports 28a, 30a, 32a, 34a of the main multiple valve body 20 and the pilot lines 28c, 30c, 32c, 34c, respectively. And the ports 28b, 30b, 32b, 34b of the pilot multiple valve valve body 26.
Further, the main multi-valve valve body 20 is provided with a logic valve 36 in the oil supply oil passage 56 of the boom cylinder, and the pilot valve 22 has a floating position 22d in addition to the exit position 22a, the neutral position 22b, the entry position 22c. The logic valve 36 and the pilot valve 22 are connected via a port 38a, a pilot line 38c, and a port 38b.

Regarding the operation of the hydraulic control valve device configured as described above,
Explaining the boom cylinder 12, the pilot valve
When 22 is in the entry position, for example, position 22c, the pilot pressure of pilot pump 21 acts on port 28a via pilot line 28c, port 28b, inlet oil passage 37, and inlet port 40. The port 30a is connected to the pilot line 30.
The unit valve 16 is in the actuated position 16a as it communicates with the tank 46 via c, port 30b, return oil passage 42 and outlet port 44, while port 38b is blocked so that the orifice of the logic valve 36 is Oil does not flow to 36b, the pressure of boom cylinder port 12a acts on large diameter chamber 36a, and logic valve 36
Is blocked. Therefore, the unit valve 16 blocks the center bypass oil passage 48, the inlet port 50 connected to the main pump 10 communicates with the cylinder port 12a, and the boom cylinder 12 is driven downward in FIG. The return oil from the boom cylinder 12 should be
It is discharged from 12b to the tank 46 via the return oil passage 52 and the outlet port 54. Next, when the pilot valve 22 is in the floating position 22d, the pressure acting on the ports 28a and 30a is the same as in the case described above, so the unit valve 16 is also in the driving position 16a. However, the port 38b has a return oil passage 42 and an outlet port 44.
Since the large diameter chamber 36a of the logic valve 36 communicates with the tank 46 through the port 38a and the pilot line 38c, the oil flows through the orifice 36b. Therefore,
The differential pressure generated at the orifice 36b opens the logic valve 36. In this manner, one cylinder port 12a of the boom cylinder 12 is also connected to the tank 46 via the return oil passage 52 and the outlet port 54, like the other cylinder port 12b.

[Problems to be solved by the device]

However, the conventional logic valve described above has the following drawbacks.

That is, when the pilot valve 22 is in the neutral position 22b, and therefore the unit valve 16 is also in the neutral position 16b, the amount of oil leakage from the logic valve 36, that is, from the logic valve large diameter chamber 36a due to the holding performance of the boom cylinder 12. The amount of oil that leaks to the tank 46 through the port 38a, pilot line 38c, port 38b, pilot valve 22, return oil passage 42, and outlet port 44 must be reduced. However, since the pilot valve 22 is a spool valve, oil leaks from the gap between this spool and the pilot multiple valve valve body 26, the holding performance of the boom cylinder 12 deteriorates, and the amount of leakage decreases. However, there is a difficulty in tightly controlling the fitting gap. Further, since the pressure of the main pump 10 acts on the port 38a,
Since the pilot line 38c has to be configured as a high-pressure pipe, its equipment cost increases.

Therefore, an object of the present invention is to ensure the sealability of the logic valve, thereby reducing the amount of oil leakage and configuring the pilot line for communicating between the logic valve and the pilot valve for a low pressure shovel. An object is to provide a hydraulic control valve device for a loader.

[Means for Solving the Problems]

In order to achieve the above object, the hydraulic control valve device for a shovel loader according to the present invention has a plurality of unit valves for controlling the directions of a boom cylinder driven by the discharge oil of the main pump and other actuators. The main multi-valve valve body and the pilot multi-valve valve body having a plurality of pilot valves for operating the unit valves each operated by the discharge oil of the pilot pump, and the main multi-valve valve body is a logic valve. Is provided in an oil supply oil passage connected to the boom cylinder, the pilot valve has a floating position, and when the pilot valve is in the floating position, the oil supply oil passage of the boom cylinder is connected to the logic valve. A hydraulic control valve device for a shovel loader that can communicate with a tank through a logic valve large diameter chamber that communicates with the oil supply oil passage through an orifice, and is connected to the tank. While communicating with the return oil passage of the main multiple valve valve body through a small hole, the pilot seat provided in the small hole is controlled to open and close with a pilot poppet,
A piston connected to a pilot chamber in which one end of the pilot poppet is adjacent and the other end is connected to the pilot valve is provided, the diameter of the piston is configured to be larger than the diameter of the pilot seat, and the pilot valve is provided in a position other than the floating position. In some cases, the pilot pump discharge oil pressure is applied to the pilot chamber, and when the pilot valve is in the floating position,
The pilot chamber is connected to the tank.

[Operation] The pilot poppet of the logic valve according to the present invention is provided with the first pressing force by the pilot pump pressure acting on the piston pressure receiving surface, and the oil supply of the boom cylinder acting on the pilot seat through the orifice of the main poppet. The second pressing force due to the pressure of the oil passage is applied so as to face each other. The pressure in the oil supply passage of the boom cylinder may be higher than the pilot pump pressure,
Since the area of the piston pressure receiving surface is set sufficiently larger than the area of the pilot seat, the first pressing force is set to be sufficiently larger than the second pressing force.

However, when the pilot valve is in a position other than the floating position, the pilot poppet is loaded with the first and second pressing forces, but as described above, the first pressing force is large, so the pilot poppet is Closes the pilot seat and the logic valve is closed. On the other hand, when the pilot valve is in the floating position, the first pressing force is not applied, so the pilot poppet is opened by the second pressing force, and the hydraulic oil in the oil supply oil passage of the boom cylinder is forced to flow through the orifice. The main poppet is also opened by the pressure difference generated by the passage. Therefore, the hydraulic oil supply oil passage of the boom cylinder is communicated with the tank via the return oil passage.

Further, in the logic valve of the present invention, the seat portion is reliably closed by the pilot poppet between the large diameter chamber of the logic valve and the return oil passage connected to the tank. It is not necessary to strictly manage the fitting gap with the pilot multi-valve valve body, and the pilot line can use inexpensive piping for low pressure.

〔Example〕

An embodiment of a hydraulic control valve device for a shovel loader according to the present invention will be described in detail below with reference to the accompanying drawings. For convenience of explanation, the same components as those of the conventional structure shown in FIG. 3 are designated by the same reference numerals and detailed description thereof will be omitted.

The hydraulic control valve device for a shovel loader according to the present invention is basically the same as the conventional device shown in FIG. That is, in FIG. 1, the hydraulic control valve device has a main unit having two unit valves 16 and 18 for controlling the directions of the boom cylinder 12 driven by the discharge oil of the main pump 10 and the other cylinders for bucket 14, for example. A multi-valve valve body 20 and a pilot pump 21 for operating the two unit valves 16 and 18 respectively.
And a pilot multi-valve valve body 26 having two pilot valves 22 and 24 for controlling the direction of the discharged oil. Then, between the unit valve 16 and the pilot valve 22 and between the unit valve 18 and the pilot valve 24, the ports 28a and 30 of the main valve unit 20 are respectively provided.
a, 32a, 34a, pilot lines 28c, 30c, 32c, 34c, and ports 28b, 30b, 32b, 34b of the pilot multiplex valve 26, and the main multiplex valve body 20 for boom A logic valve 60 is provided in the oil supply oil passage 56 of the cylinder, and the pilot valve 22 has a floating position 22d in addition to the exit position 22a, the neutral position 22b, the entry position 22c, and the logic valve 60 and the pilot valve 22.
Between port 38a, pilot line 38c, port 38b
Connected via.

Therefore, as shown in detail in FIG. 2, the logic valve 60 in the hydraulic control valve device of the present invention is connected to the boom cylinder 12 via the cylinder port 12a.
A piston arranged in a pilot chamber 68 that communicates with a main poppet 66 with an orifice 64 that controls opening and closing between the 6 and the return oil passage 52, and a port 38b connected to the pilot valve 22 via a port 38b and a pilot line 38c. 70 and a pilot poppet 72 provided in a pilot poppet chamber 74 adjacent to this piston, and the oil supply oil passage 56
The small diameter hole 76 communicates between the large diameter chamber 62 and the pilot poppet chamber 74 communicating with each other through the orifice 64, and the pilot seat 78 provided in the small hole 76 is opened and closed by the pilot poppet 72. The pilot poppet chamber 74 is returned to the return oil passage 52 through the right angle hole 80 and the annular oil passage 82.
It is configured to communicate with.

Next, the operation of the hydraulic control valve device for a shovel loader of the present invention having such a configuration will be described. The operation of the unit valve 18 and the pilot valve 24 on the bucket cylinder 14 side is easily inferred from the operation of the unit valve 16 and the pilot valve 22 on the boom cylinder 12 side. Only the cylinder 12 side will be described.

First of all, when the pilot valve 22 is in the neutral position 22b, in the pilot multiple valve valve body 26, all the lines connected to the inlet oil passage 37 are blocked, so that the inlet port 40 from the pilot pump 21 is changed. The pressure in the line supplied with the discharge oil via the pilot relief valve 90
Is maintained at a pressure set by, usually around 30 kg / cm ² . Also, the ports 28b and 30b are connected to the return oil passage 4
2. Since it communicates with the tank 46 through the outlet port 44, the pressure inside these is substantially equal to the atmospheric pressure. On the other hand, in the main multi-valve valve body 20, the ports 28a, 30a
Port 28 via pilot lines 28c and 30c respectively
Since it is communicated with b and 30b, it is also maintained at substantially the same atmospheric pressure. Therefore, the unit valve 16 is at the neutral position 16b shown, and the oil discharged from the main pump 10 is returned to the tank 46 through the center bypass passage 48 and the outlet port 54. On the other hand, since the port 38b communicates with the inlet oil passage 37, the discharge pressure of the pilot pump 21 acts on this port 38b, and this pressure is applied to the logic valve via the pilot pipe 38c and port 38a. Acting on 60 pilot chambers 68. Therefore, the piston of the logic valve 60
70 is a force (first pressing force) having a magnitude of Pa = (pressure receiving area of piston 70) × (pilot pump pressure), which pushes the pilot poppet 72 to the right to close the seat 78, and thus the logic valve. 60 is closed.

At this time, if an external force acts on the boom cylinder 12 and a pressure is generated in the oil supply oil passage 56, the pilot poppet 72
Is Pb = (area of pilot seat 78) x (oil supply oil passage)
(Pressure of 56) force toward the left (second pressing force)
However, since the diameter of the piston 70 is sufficiently larger than the diameter of the pilot seat 78, the condition of Pa> Pb is always maintained, and the pilot seat 78 remains closed.

Next, when the pilot valve 22 is operated to the on position, for example, the position 22c, the pressures of the ports 38b and 30b do not change, the pressure of the pilot pump 21 acts on the port 38b, and the port 30b communicates with the tank 46. There is. On the other hand, the port 28b is connected to the inlet oil passage 37.
The pressure of the pilot pump 21 acts similarly to the port 38b. Therefore, in the main multi-valve valve body 20, the pilot pump pressure acts on the port 28a,
The unit valve 16 moves to the drive position 16a, the center bypass passage 48 is blocked, the inlet port 50 communicates with the port 12a, the discharge oil of the main pump 10 flows into the rod side of the boom cylinder 12, and the boom cylinder 12 moves. It is driven downward in FIG. On the other hand, the return oil from the head side of the boom cylinder 12 is discharged into the tank 46 via the port 12b, the return oil passage 52, and the outlet port 54. The main relief valve 92
Is for setting the pressure of the oil discharged from the main pump 10 that has flowed into the inlet port 50. When the pressure exceeds the set pressure, the oil that has flowed in flows out to the return oil passage 52. Also a logic valve
As described above, 60 is a force of Pa = (pressure receiving area of piston 70) × (pilot pump pressure) from the left side of pilot poppet 72, and Pb = (area of pilot seat 78) from the right side. A force of the magnitude of × (pressure of the oil supply oil passage 56) is received, but in this case as well, the diameter of the piston 70 is sufficiently larger than the diameter of the pilot seat 78 so that Pa> Pb is always maintained. The pilot poppet 72 blocks the pilot seat 78, and the discharge oil of the main pump 10 does not flow from the oil supply oil passage 56 to the return oil passage 52 via the logic valve 60.

Next, when the pilot valve 22 is operated to the floating position 22d, the pressure at the ports 28b and 30b does not change, so the unit valve 16 is set to the driving position 1
Held at 6a. On the other hand, since the port 38b communicates with the tank 46 via the return oil passage 42 and the outlet port 44, the port 38a of the main multi-valve valve body 20 becomes the tank pressure via the pilot line 38c. Therefore, in the logic valve 60, the pilot chamber 68 becomes the tank pressure, and the pilot poppet 72 receives the pressure of the large diameter chamber 62 and shifts to the left side in FIG.
The pilot seat 78 is opened. This allows the oil supply oil passage
The pilot oil of the discharge oil of the main pump 10 which has flown into 56 returns via the oil supply oil passage 56, the orifice 64, the small hole 76, the pilot seat 78, the pilot poppet chamber 74, the shaft right angle hole 80, and the annular oil passage 82. It flows to the oil passage 52. Due to this flow, the pressure difference generated in the orifice 64 causes the main poppet 66 to move to the left side in FIG.
84 is opened, and most of the oil discharged from the main pump 10 directly flows out from the main seat 84 portion to the return oil passage 52. The oil in the return oil passage 52 is discharged into the tank 46 via the outlet port 54. Thus, when the pilot valve 22 is in the floating position,
Since the cylinder ports 12a and 12b and the inlet port 50 are all in communication with the tank 46 via the outlet port 54, the boom cylinder 12 can have a floating function.

When the pilot valve 22 is operated to the exit position 22a, the boom cylinder 12 is driven upward in FIG.
The operation in this case is easily inferred from the operation when the pilot valve 22 is operated to the entry position 22c, and therefore the description thereof will be omitted.

As described above, according to the hydraulic control valve device of the present invention, since the sealing property of the logic valve itself is improved, it is not necessary to strictly manage the fitting gap between the spool of the pilot valve and the pilot multiple valve valve body. There is an advantage that a pipe for low pressure can be provided between the logic valve and the pilot valve.

Although the present invention has been described above with reference to the preferred embodiments, the present invention can be modified in many ways without departing from the spirit thereof.

[Effect of device]

As described above, the hydraulic control valve device for a shovel loader according to the present invention includes a main multi-valve valve body having unit valves for a boom cylinder and other actuators, and a plurality of pilots for operating the unit valves. In a hydraulic control valve device comprising a pilot multiple valve body having a valve, a logic valve is installed in the oil supply oil passage of the boom cylinder to give the boom cylinder a floating function,
In the logic valve, a piston in which the pressure of the pilot chamber connected to the pilot valve acts on one end surface, a pilot poppet is provided adjacent to the piston, and further, a large diameter chamber of the logic valve and a return oil passage connected to the tank. Since a small hole having a pilot seat is provided between the pilot poppet and the pilot poppet to control the opening and closing of the pilot seat, and the pilot chamber is communicated with the tank at the floating position of the pilot valve, the pilot valve floats. In the position, the logic valve is opened to allow the boom cylinder to have a floating function, and in the pilot valve inlet and outlet positions and the neutral position, the logic valve is closed and the logic valve large diameter chamber and the return oil passage. Or, the space between the tank and the tank is reliably sealed.

Furthermore, since the pilot line between the logic valve and the pilot valve can be configured to have a low pressure structure, the piping cost can be reduced.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram for explaining an embodiment of the hydraulic control valve device for a shovel loader according to the present invention, and FIG. 2 is a logic valve of the hydraulic control valve device for a shovel loader according to the present invention shown in FIG. FIG. 3 is an enlarged vertical sectional view showing an embodiment, and FIG. 3 is a hydraulic circuit diagram for explaining a conventional hydraulic control valve device for a shovel loader. 10 …… Main pump 12 …… Boom cylinder 12a, 12b …… Boom cylinder port 14 …… Bucket cylinder 14a, 14b …… Bucket cylinder port 16 …… Unit valve 16a, 16c …… Drive position, 16b… … Neutral position 18 …… Unit valve, 20 …… Main multiple valve valve body 21 …… Pilot pump 22 …… Pilot valve 22a …… Out position, 22b …… Neutral position 22c …… In position, 22d …… Floating position 24 …… Pilot valve 26 …… Pilot multiple valve valve body 28a, 28b, 30a, 30b, 32a, 32b, 34a, 34b, 38a, 38b …… Port 28c, 30c, 32c, 34c, 38c …… Pilot line 37 …… Inlet oil passage, 40 …… Inlet port 42 …… Return oil passage, 44 …… Outlet port 46 …… Tank 48 …… Center bypass oil passage 50 …… Inlet port, 52 …… Return oil passage 54 …… Outlet Port 56 56 Oil supply oil passage 60 Logic valve 62 Logic valve large diameter chamber 64 Orifice 66 Main poppet 68 Pilot Chamber, 70 …… Piston 72 …… Pilot poppet 74 …… Pilot poppet chamber 76 …… Small hole 78 …… Pilot seat 80 …… Axial right-angle hole, 82 …… annular oil passage 84 …… Main seat 90 …… Pilot relief valve 92 ... Main relief valve

Claims (1)

[Scope of utility model registration request] 1. A main multi-valve valve body having a boom cylinder driven by the discharge oil of a main pump and a plurality of unit valves respectively controlling the directions of a plurality of other actuators, and a pilot pump operated by the discharge oil. And a pilot multi-valve valve body having a plurality of pilot valves for respectively operating the unit valves, the main multi-valve valve body is provided with an oil supply oil passage connecting a logic valve to the boom cylinder, and The pilot valve has a floating position, and when the pilot valve is in the floating position, in a hydraulic control valve device for a shovel loader capable of communicating the oil supply oil passage of the boom cylinder with the tank via the logic valve, It is common to communicate through a small hole between the logic valve large-diameter chamber communicating with the oil supply oil passage through an orifice and the return oil passage of the main multiple-valve valve element connected to the tank. In addition, the pilot seat provided in the small hole is opened and closed by the pilot poppet,
A piston connected to a pilot chamber in which one end of the pilot poppet is adjacent and the other end is connected to the pilot valve is provided, the diameter of the piston is configured to be larger than the diameter of the pilot seat, and the pilot valve is provided in a position other than the floating position. In some cases, the pilot pump discharge oil pressure is applied to the pilot chamber, and when the pilot valve is in the floating position,
A hydraulic control valve device for a shovel loader, wherein the pilot chamber is connected to the tank.