JPS5997301A - Fluid control device - Google Patents

Abstract

PURPOSE:To perform accurate meter-out control by controlling a meter-out valve mechanism by means of a meter-in valve mechanism. CONSTITUTION:A meter-in valve mechanism (a) is mainly composed of a flow rate adjustment selector valve 21 and a pressure control valve 22, while a meter- out valve mechanism (b) is mainly composed of meter-out valves 23, 24. According to change over of a spool 38 of a flow rate adjustment selector valve 21, opening of a pilot passage 64 is determined correspondingly to the change over quantity and the pilot pressure corresponding to the flow rate is generated to be exerted on a rod 92, to have the rods 92, 91 pushed leftward. Pressure in a relay chamber 83 is applied on a stepped part 99 and made to act as a force against the pilot pressure. The rods 92 and 91 move in proportion to the change over quantity of the spool 38, and a notch part 97 opens toward the pressure chamber 77 side, and the pressure in said chamber 77 is lowered. A main poppet 71 moves in proportion to the quantity of movement of the rod 91 to determine the opening area of a seat part 81, and meter-out control can be performed so that a cylinder 57 can be controlled even during operation of negative load.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluid control device that performs load sensing control and meter-out control.

(Conventional Control Device) The conventional control device shown in FIG. The pilot pressure is also introduced into the pilot chamber 7 of one of the valves 5.6.

For example, by operating the manual operating device 1, the pilot passage 8 is
When pilot pressure is introduced into the meter-in valve 2, the pilot pressure flows into one pilot chamber 3 of the meter-in valve 2 and the pilot chamber 7 of the meter-out valve 5.

When pilot pressure is introduced into the pilot chamber 3 as described above, the meter-in valve 2 moves to the right side in the drawing,
The main passage 9 and the load boat 10 are communicated with each other. Therefore, the working fluid from the pump 11 is transferred to the load check valve 1
2 is pushed open and flows into the rod side chamber 14 of the cylinder 13, causing the cylinder 13 to contract.

Further, as described above, when pilot pressure flows into the pilot chamber 7 of one of the meter-out valves 5, the meter-out valve 5 opens and the bottom side chamber 15 of the cylinder 13 is opened.
is communicated with the tank passage 17 via the flow passage 1G.

Therefore, the working fluid on the return side from the bottom side chamber 15 returns to the tank 18.

The meter-in/club 2 in this conventional control device
Due to the fluid force of the working fluid flowing from the main passage 9 to the load port 10, the
It maintains a self-compensation function so that the flow rate is proportional to the pilot pressure.

However, because of this self-compensation function, when load pressure fluctuations or pump pressure fluctuations occur, the meter-in valve 2
performs a self-compensating operation, but at this time the pilot room 3.4
A change in volume occurs. When a volume change occurs in the pilot chamber 3.4, the pilot pressure fluctuates, and this fluctuation acts on the meter-out valve 5 or 6.

When the fluctuated pilot pressure acts on the meter-out valve as described above, it adversely affects the valve function, resulting in the drawback that accurate meter-out control cannot be performed.

(Objective of the Present Invention) An object of the present invention is to provide a fluid control device that eliminates the above-mentioned conventional drawbacks by controlling a meter-out valve mechanism by a meter-in valve mechanism.

(Embodiment of the present invention) In the first embodiment shown in FIG. 2.3, a meter-in valve mechanism a is provided downstream of the variable pump 20, and a meter-in valve mechanism a is further provided downstream of the meter-in valve mechanism a. An out valve mechanism is provided.

The meter-in valve mechanism a has a flow rate adjustment switching valve 21 and a pressure control valve 22 as main elements, and the meter-out valve mechanism a has a pair of meter-out valves 23 and 24 as main elements. The general configuration is shown in Figure 3.

That is, each of the above elements is installed inside the valve body 25, and the pressure control valve 22 is provided at the most upstream side thereof.

The pressure and force control valve 22 has a pore 2 formed in the valve body 25.
6 has a spool 27 slidably installed inside.

The pore 26 has a first annular groove 28 and a second annular groove 2.
8, the first annular groove n28 is always in communication with the inflow passage 3o of the flow rate adjustment switching valve 21, and the second annular groove 28 is always in communication with the variable pump 20 via the main passage 31. There is.

The spool 27 has one end facing one pilot chamber 32 and the other end facing the other pilot chamber 32.
3, and an annular recess 34 is formed in the center. The other pilot chamber 33 has a spring 3.
5 is interposed, and the spool 27 is normally maintained in the illustrated state by the action of the spring 35.

That is, in the above state, the working fluid from the variable pump 20 flows from the main passage 31 to the second annular groove 28 to the annular recess 34.
→It is in a relationship that it flows into the inflow passage 30 via the first annular groove 28. At this time, the pressure on the inflow passage 30 side passes through the orifice 36 to the one pilot chamber 32.
flows into.

Further, the flow rate adjustment switching valve 21 has a spool 38 slidably installed in a pore 37 formed in the valve body 25. The spool 38 has one end protruding outside the valve body 25, and the other end thereof. facing the spring chamber 3θ. The spool 38 is normally maintained at the neutral position shown in the figure by the action of the spring 40 interposed in the spring chamber 3B.

In the illustrated state, an annular recess 41 formed at the center of the spool 38 corresponds to the inflow passage 30, and the inflow passage 30 is closed by lands 42, 43 formed on both sides of the annular recess 41.

The lands 42 and 43 are formed with tapered surfaces or notches that taper toward the annular recess 41.

Then, from the above state, the spool 38 is connected to the spring 4.
0, the annular groove 44 or 45 that communicates with the load boat 4B or 47 is moved to the left or right.
One of the annular grooves communicates with the inflow passage 30.

Furthermore, a load detection boat 48.48 is formed outside the annular groove 44.45 and at a position substantially adjacent thereto, and this load detection boat 48.48 is configured as described above. The load boat 4 communicates with the inflow passage 30.
The pressure in B or 47 is introduced as two pilot pressures into the other pilot chamber 33 of the pressure control valve 22, and at the same time, the pilot pressure is introduced into a shuttle valve 50 to be described later. However, when the spool 38 is in the illustrated neutral position, the load detection port 48, 48 is communicated with the tank 52 through the passage 51 formed in the spool 38, and the load detection port 48, 48 is connected to the tank 52 in the neutral position. I try not to build up pressure.

The load ports 46, 47 as described above are connected to the control ports 55, 56 via load check valves 53, 54.
These re-control ports 55, 58 are connected to the bottom chamber 58 and the rod chamber 58 of the cylinder 57, respectively.

The spool 38 also has a pilot pressure switching notch 6.
0, and this pilot pressure switching notch 80 is connected to a branch passage 61 branched from the main passage 31.
A pressure reducing valve 82 is provided in the flow process of this branch passage 81.

When the spool 38 is in the neutral position, the pilot pressure switching notch 60 is closed, and when the spool 38 is switched to the left or right, it communicates with either the pilot passage 63 or 64, and the spool 38 is in communication with either the pilot passage 63 or 64.
The opening area for the pilot passage 63 or 84 is determined according to the amount of movement of the pilot passage 8.

The pilot passage 63.64 is an orifice 65.66.
Since it communicates with the tank 52.87 via the pilot passage 63 or 84, the pilot pressure corresponding to the opening area for the pilot passage 63 or 84 is
Occurs on 4th.

The pilot pressure generated as described above flows into the meter-out valve mechanism, and the configuration of this meter-out valve mechanism is as follows.

That is, the pores 6 and 69 are located on the most downstream side of the valve body 25.
These pores 68 and 89 are opposed to each other with the tank passage 70 in between. A main poppet 71.72 is provided inside this pore 68.68, and a first guide member 73.74 is fixed to the outside of this main poppet 71.72, and furthermore, this first guide member A second guide member 75, 78 is fixed to the outside of 73, 74.

And the pressure chamber formed between the main poppet 71.72 and the first guide member 73.74? ? , 78 with a spring 79.80 interposed therein, and this spring 79.8
Normally, due to the action of 0, the above main bope, )71.72,
A seat portion 81. formed on the control port 55, 56 side.
82, tank passage 70 and control port 55.58
communication with is cut off.

In addition, the first guide member 73, 74 and the second guide member 7
A relay chamber 83.84 formed between the control boat 55 and the control boat 55 communicates with the pressure chamber 77.78 via an orifice 85.88 and communicates with the control boat 55 via a passage 87.88.
．． It also connects to 56. Furthermore, a second guide member 75.
A pilot chamber 88,90 formed in the pilot passage 63 via damper orifices 128, 127
．． It is connected to 64.

A hole is formed in the center of each of the main poppet 71.72, the first guide member 73.74, and the second guide member 75.76 as described above, and a rod 91.82 is inserted into the hole.
are slidably passed through the rods 81, and both rods 81
．． The inner ends of 82 abut against each other within the tank passage 70.

Both ends of the rods 81, 82 are in contact with spring guides 93, 94, and the spring guides 83, 94 push the rods 81, 82 by the action of their springs 95, 98, and normally is rod 91.
82 is held in the neutral position shown.

When the rods 81, 82 are held in the neutral position as described above, communication between the tank passage 70 and the pressure chambers 77, 78 is cut off, but if they move against the spring force of the springs 95, 96. At this time, the pressure chambers 77, 78 and the tank passage 70 communicate with each other through the notches 87, 98 formed in the rods 91, 82.

The rods 81 and 82 also include the relay chambers 83 and 84.
A step 98.100 is formed on which the pressure introduced inside acts, and the inner diameter D1 is larger than the outer diameter D2 at this step.

In addition, the symbols 101 and 102 in the figure are anti-void valves,
103 and 104 are relief valves.

In this first embodiment, a meter-in valve mechanism a' having a similar configuration and a meter-out valve mechanism b' associated therewith are provided on the downstream side of the meter-in valve mechanism a.

Since each of these mechanisms is the same as described above, a detailed explanation of each of these elements will be omitted, but new symbols will be added as necessary.

The fluid control device equipped with the valve mechanism as described above has an output detection passage 105 provided in the main passage 31, and this output detection passage 105 is connected to the differential pressure sensing control valve 10B and the safety valve 107.
It is connected to a tilt angle control device 108 consisting of.

The differential pressure sensing control valve 10B is located in one of the pilot chambers.
The pressure from the output detection passage 105 is introduced into the pilot chamber 109 , and the other pilot chamber 110 is provided with a spring 111 and connected to the shuttle valve 50 via a load detection passage 112 .

The shuttle valve 5o connected to the load detection passage 112 is connected to the load detection boats 48 and 49 via the load detection passage 124, and at the same time, the shuttle valve 5o is connected to the load detection boats 48 and 49 of the downstream meter-in valve mechanism a'. They are connected via a detection passage 125.

Therefore, the load pressure of either the upstream actuator or the downstream actuator, whichever is higher, is the shuttle valve 5.
0 will be selected and introduced into the pilot room 110.

It goes without saying that a check valve may be provided in place of the shuttle valve 50.

The differential pressure sensing control valve 10B is connected to the pilot chamber 10.
8 and the pilot chamber 110, and when the pressure in one pilot chamber 109 is higher than the pressure in the other pilot chamber 110, the differential pressure sensing control valve 1013 acts against the spring 111 as shown in the drawing. Switch to left position. When the differential pressure sensing control valve 106 is switched in this way, the flow from the output detection passage 105 returns to the variable pump 2.
Since the working fluid of 0 flows into the tilt angle control cylinder 114 through the passage 113, the discharge amount of the variable pump 20 is reduced.

On the other hand, when the pressure in the other pilot chamber 108 becomes higher than the pressure in the one pilot chamber 108, the differential pressure sensing control valve 108 is held at the right position as shown in the figure and the tilt angle control cylinder 114 is communicated with the tank 115. , the piston of the tilt angle control cylinder 114 moves under the action of a spring, increasing the discharge amount of the variable pump 20.

However, if only the upstream cylinder 57 is operated and the spool 38 is switched to the right in FIG. 3, the inflow passage 30 and the load boat 47 will communicate with each other.
The opening area during the communication process is determined according to the amount of movement of the spool 38.

As described above, the inflow passage 30 has a predetermined opening area.
When the and load boat 47 communicate with each other, the working fluid from the variable pump 20 passes through the pressure control valve 22 → inflow passage 30 → annular recess 41 → load port 47 → load check valve 54 and enters the rod side chamber 59 of the cylinder 57. Inflow.

When the spool 38 is switched to the right as described above, the pilot pressure switching notch 60 and the pilot passage 84 are brought into communication, and the amount of opening thereof is determined according to the amount of movement of the spool 38. Once the opening amount is determined, the pressure reducing valve 62
The pilot flow rate that flows in via is determined, and the determined pilot flow rate flows from the pilot passage 64 to the tank B7 through the orifice 86, but a pressure difference is generated before and after the orifice 66 according to the pilot flow rate.

The pilot pressure generated in this manner flows into the pilot chamber 80 and acts on the outer end surface of the rod 82.

When pilot pressure is introduced into the pilot chamber 80 as described above, the rod 82 is pushed leftward in the drawing by the action of the pilot pressure. Along with this, the rod 81 is also pushed, and the notch 87 of the rod 81 opens into the pressure chamber 77 .

If the notch 97 opens into the pressure chamber 77, this pressure chamber 7
7 communicates with the tank passage 70 and its pressure decreases, so the high pressure on the control boat 55 side causes the main pump) 71
opens, and the control boat 55 communicates with the tank passage 70.

Therefore, the fluid on the return side of the bottom side chamber 58 is
Returning to step 6, the cylinder 57 contracts.

When the cylinder 57 operates as described above, the load pressure on the load boat 47 side is introduced from the load detection boat 49 into the other pilot chamber 33 of the pressure control valve 22. The pressure on the inflow passage 3o side is introduced into the inlet 32 through the oriice 38.

At this time, the pressure control valve 22 remains within the range where the pressure P1 on one pilot chamber 32 side, the pressure P2 on the other pilot chamber 33 side, and the pressure P3 corresponding to the spring force of the spring 35 maintain the relationship Pl=P2+P3. is balanced, and the opening amount between the annular recess 34 and the inflow passage 30 is adjusted to control the differential pressure before and after the spool 38 to be constant. Therefore, when switching the spool 38, a flow rate proportional to the opening area of the spool 38 is obtained, and as a result, a predetermined flow rate is supplied to the cylinder 57 regardless of its load fluctuation.

At this time, the discharge pressure of the variable pump 2o is
5 into one pilot chamber 109 of the tilt angle control device 108, while the load pressure on the rod side chamber 58 side flows from the annular groove 45→load detection passage 124→shuttle valve 50→
The other pilot chamber 11 via the load detection passage 112
Flows into 0.

Therefore, the differential pressure sensing control valve 106 has a pressure P in one of the pilot chambers 109, and a pressure P in the other pilot chamber 109.
The pressure P2 in the spring 10 and the pressure P3 corresponding to the spring force of the spring 111 are balanced in the following relationship: P1=P2+P3.

For example, when the pressure P1 on the pilot chamber 108 side is higher than the pressure P2+P3 on the pilot chamber 110 side, the differential pressure sensing control valve 108 moves against the spring 111, stops at the position balanced at P2+P3, and output is detected. The passage 105 and the passage 113 are communicated with each other. Therefore, the discharge amount of the variable pump 20 flows into the tilt angle control cylinder 114, and the discharge amount of the variable pump 20 is reduced.

On the other hand, if P1 becomes lower than P2+P3, the differential pressure sensing control valve 106 switches, the fluid in the cylinder 114 flows to the tank 115, and the variable pump 20 changes accordingly.
The discharge amount is also increased.

The discharge amount of the variable pump 20 is determined as described above, but the discharge amount is determined within a range that satisfies the conditions of P, = P2 + i = '3, and in the end, the pump discharge pressure and the load pressure are determined. The pump discharge amount is controlled so that the differential pressure between the two is equal to the pressure corresponding to the spring force.

On the other hand, when a load acts on the cylinder 57 in the direction of arrow 128 shown in FIG. 2 and pressure is supplied to the rod side chamber 58 side, that is, when a negative load acts on the cylinder 57, the meter-in valve mechanism a Unable to control cylinder.

This is because when a negative load is acting as described above, the cylinder moves with the load pressure rather than the supply pressure from the pump, so it is not possible to control the cylinder by controlling the flow rate on the supply side. .

In such a case, the meter-out valve mechanism functions, and its specific operation is as follows.

That is, when the spool 38 of the flow rate adjustment switching valve 21 is switched to the right in the drawing as described above, the opening degree of the pilot passage B4 is determined according to the switching amount.

Once the opening degree of the pilot passage 64 is determined, a flow rate corresponding to the opening degree flows, and a pilot pressure corresponding to the above flow rate is generated by the function of the orifice 6B.

This pilot pressure flows into the pilot chamber 90 and acts on the rod 92, pushing the rods 92 and 91 leftward in the drawing.

At this time, the pressure on the control port 55 side is flowing into the pressure chamber 77 and the relay chamber 83, but the pressure inside the relay chamber 83 acts on the stepped portion 89, and the force is applied to the rods 82 and 81.
It acts as a force that opposes the

Therefore, the rod 9 pushed by the pilot pressure
2 and 81 move to a position where the pressing force due to the pilot pressure and the force acting on the spring 95 and the stepped portion 88 are balanced. In other words, the rods 92 and 81 move in proportion to the pilot pressure, that is, the switching amount of the spool 38.

When the rod 81 moves as described above, the notch 87 opens toward the pressure chamber 77 and communicates the pressure chamber 77 with the tank passage 70 . When the pressure chamber 77 communicates with the tank passage 70, the pressure inside the pressure chamber 77 decreases due to the action of the orifice 85. When the pressure inside the pressure chamber 77 decreases in this way, the main poppet 71 moves in proportion to the amount of movement of the rod 81 due to the action of the high pressure on the control boat 55 side, thereby determining the opening area of the seat portion 81.

If the seat part 81 is opened as described above, the control port 5
5 and the tank passage 70 communicate with each other, and a flow rate corresponding to the opening degree of the seat portion 81 flows into the tank passage 70.

In other words, the pilot pressure is determined according to the switching amount of the spool 38 of the flow rate adjustment switching valve 21, the amount of movement of the main poppet 71 is also determined in proportion to the pilot pressure, and the seat portion 81 has an opening area proportional to the pilot pressure. will be maintained.

If the opening area of the seat portion 81 is thus obtained in proportion to the pilot pressure, meter-out control can be performed according to the opening area, and the cylinder 57 can be controlled even when the above-mentioned negative load is applied.

Then, in the above condition, there is a load fluctuation on the cylinder in question,
When the pressure on the return side changes, the rod 91.82 senses the pressure change as a change in the force acting on the step 88.

Therefore, when the pressure on the outflow port 55 side increases while the opening area of the seat portion 81 is constant, the flow rate flowing into the tank passage 70 tends to increase in accordance with the pressure increase.

However, at this time, the pressure within the relay chamber 83 also rises, and the force acting on the stepped portion 99 also increases, so that the rod 81.
82 moves to the right in the drawing. As the rod moves, the main poppet 71 follows and self-adjusts so as to reduce the opening area of the seat portion 81 and cancel the increase in the amount of outflow.

Conversely, when the pressure on the control port 55 side decreases, the amount of outflow flowing into the tank passage 70 tends to decrease in accordance with the pressure drop. However, at this time, the pressure within the relay chamber 83 also decreases, and the force acting on the step portion 99 also decreases.
Rods 91, 82 move to the left in the drawing. As the rod moves, the main poppet 71 follows and increases the opening area of its seat portion 81 to self-adjust to compensate for the decrease in the outflow amount.

In other words, even if the pressure on the control boat 55 side changes, the opening area of the seat portion 81 is automatically increased or decreased to maintain a self-compensating function to prevent changes in the flow rate on the return side.

Note that the pressure receiving areas of the first step portions 99 and 100 do not need to be equal; for example, if the direction of the load is fixed at a certain number, the pressure receiving area of one step portion may be made larger. You can stay there.

Further, the control operation when simultaneously operating the motor 117 connected to the meter-in valve mechanism a' side and the cylinder 57 is substantially the same as when only the cylinder 57 is operated, but the meter-in valve The pressure control valve 22 on the mechanism a side and the pressure control valve 118 on the meter-in 7<lub mechanism a' side function to prevent the variable pump 20 from insufficiently supplying working fluid only to the actuator with the lower load.

Further, the higher load pressure of the actuators is selected by the shuttle valve 50 and introduced into the load detection passage 112,
The discharge amount of the variable pump 20 is controlled between the load pressure and the load pressure.

In addition, in the above embodiment, pressure ffJI Sv valve 22
．． 118 has multiple actuators in one circuit configuration.
Required only when controlling HJ.

In other words, when operating multiple actuators at the same time, the supply flow rate from the pump is high and the load is low. % of the flow tends to flow, and as a result, working fluid is no longer supplied to the high load.

Therefore, if a pressure control valve is provided as shown in the first embodiment, the pressure control valve will operate! Since only the required flow rate is supplied to the actuator, the actuator with a low load is not supplied with working fluid.

In addition, in this fluid control device, the meter-out/< lube mechanism is controlled by the switching operation of the flow rate adjustment switching valve 21, so that the meter-out/ Even if the pump pressure changes, the pressure car J control valve 22 will only operate normally.
Meter out/<lube mechanism a4 t ± no effect.

In other words, the meter-in operation and meter-out operation are performed independently, resulting in high sensitivity. The operation of the N meter out valve mechanism can be stabilized.

The second embodiment shown in FIG.
, 120 are in the illustrated neutral position, working fluid from pump 20 flows through neutral flow path 121 to tank 116.
In addition, a restriction 122 and a low pressure relief valve 123 are provided in the flow process to the tank.

Therefore, in this second embodiment, since the working fluid passes through the restrictor 122 when the flow rate adjustment switching valve is in the neutral position, a constant flow rate is ensured in the circuit even in the neutral state. Further, the low pressure relief valve 123 suppresses the peak pressure during the switching transition of the flow rate adjustment switching valve to a low level.

In both of the embodiments described above, self-pressure is used to supply pilot pressure to the meter-out valve mechanism, but a pump for supplying the pilot pressure may be provided separately.

(Configuration of the present invention) The configuration of the present invention is such that, in a fluid control device using a valve mechanism that can control the flow rate according to the amount of movement of the spool, a constant flow rate can be maintained according to the opening degree regardless of the load fluctuation of the actuator. It is characterized in that it includes a meter-in valve mechanism that constantly supplies water, and a meter-out valve mechanism that operates by switching the meter-in valve mechanism.

With the above configuration, when the meter-in valve mechanism is operated, the meter-out valve mechanism automatically operates.
Capable of meter-in control and meter-out control.

(Effects of the Present Invention) Since the present invention is configured as described above, the operation of the meter-in valve mechanism does not adversely affect the meter-out valve mechanism.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional device, Figures 2 and 3 show a first embodiment of the present invention, Figure 2 is a circuit diagram, and Figure 3 is a diagram showing a meter-in valve mechanism and a meter-out valve mechanism. The sectional view and FIG. 4 are circuit diagrams of the second embodiment. a, a'...Meter-in valve mechanism, b, b'・Work・
Meter out valve mechanism, 3rd/fist/spool. Representative patent attorney Nobuyuki Shima 9r 1 account

Claims (1)

[Claims] In a fluid control device that uses a valve mechanism that can control the flow rate according to the amount of movement of the spool, there is a meter-in valve mechanism that always supplies a constant flow rate according to the opening degree, regardless of load fluctuations on the actuator, and A fluid control device equipped with a meter-out valve mechanism operated by a switching operation of the valve mechanism.