JP3415512B2 - Valve device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve device having a pilot flow amplification type poppet valve. 2. Description of the Related Art FIG. 3 shows a control circuit of a meter-in / meter-out separation type. FIG. 3 shows a control circuit of a bridge configuration for controlling a single rod / cylinder type hydraulic actuator 11. In this control circuit, a tank 15 is connected via a common bypass valve 14 to a discharge port of a variable displacement pump 13 capable of variably controlling a discharge flow rate by a swash plate 12, and a load hold check valve 16 is connected. Having pump line
A bridge circuit 18 is connected via 17. The bridge circuit 18 includes two meter-in valves 21 and 22 connected to the pump line 17, respectively.
It is formed by two meter-out valves 23 and 24 connected to these meter-in valves 21 and 22, respectively. [0005] These meter-out valves 23 and 24 are connected to a tank line 25.
Check valves 26 and 27 for replenishing the working oil as the working fluid from the tank line 25 to the negative pressure generating section in the circuit are connected in parallel to the tanks 23 and 24. [0006] A passage 31 drawn out between the meter-in valve 21 and the meter-out valve 23 illustrated above the bridge circuit 18 is provided with a piston of the fluid pressure actuator 11.
A passage 35 is connected to a chamber 34 (hereinafter, referred to as a “rod side chamber”) on the side where the rod 33 is located relative to 32, and is drawn out from between the meter-in valve 22 and the meter-out valve 24 shown below. Is the piston of the fluid pressure actuator 11
It is connected to a chamber (hereinafter, referred to as “head-side chamber”) 36 located on the head side of 32. The inlet sides of the meter-out valve 23 and the meter-out valve 24 form a meter-out passage, that is, a return passage 37 from the fluid pressure actuator 11. [0008] The common bypass valve 14, meter-in valve
The throttle valves 21 and 22 and the meter-out valves 23 and 24 are provided with variable throttle means such as a spool valve or a poppet valve whose opening area can be variably controlled by electromagnetic means or pilot hydraulic means. These variable throttle means are operated by a controller. In the case of electromagnetic means, control is directly performed by an electric signal output from the controller, and in the case of pilot hydraulic means, control is performed by a pilot pressure signal via electro-hydraulic conversion means. Then, the hydraulic oil supplied from the pump 13 to one of the rod side chamber 34 and the head side chamber 36 of the fluid pressure actuator 11 and discharged from the other to the tank 15 is
The control is performed by a bridge circuit 18 formed by the two meter-in valves 21 and 22 and the two meter-out valves 23 and 24. For example, when the fluid pressure actuator 11 is
When performing the extension operation against the pressure, the common bypass valve 14 is closed, the discharge amount of the pump 13 is increased, the meter-in valve 22 on the head side of the fluid pressure actuator 11 is opened, and the meter-out valve 24 is closed. The meter-in valve 21 on the side is closed and the meter-out valve 23 is opened. When the fluid pressure actuator 11 is contracted, the common bypass valve 14 is closed, the discharge amount of the pump 13 is increased, the meter-in valve 21 on the rod side of the fluid pressure actuator 11 is opened, and the meter-out valve is opened. twenty three
Is closed, the meter-in valve 22 on the head side is closed, and the meter-out valve 24 on the head side is opened. FIG. 4A shows a conventional meter-out valve.
The details of the pilot flow amplification type poppet valve device used as 23 or 24, that is, the flow amplification poppet valve device, are shown, and a poppet valve 42 is displaceably fitted into a valve fitting hole 41 formed in a valve housing 40. And
A return passage 37 from the fluid pressure actuator 11 is communicated with an inlet chamber 43 having a larger diameter than the valve fitting hole 41. A large-diameter pilot control unit 44 is formed at the left end of the poppet valve 42. A pilot flow control slot 45 is formed in the outer peripheral surface of the pilot control unit 44 in the axial direction. The slot 45 has a constant width W as shown in FIG. A part of the slot 45 is open to a spring chamber 61 described later even when the poppet valve 42 is fully closed, and the area of the opening 46 varies depending on the position of the poppet valve 42. The poppet valve 42 has a small-diameter portion 51 facing the inlet chamber 43 with respect to a large-diameter portion 47 fitted in the valve fitting hole 41 of the valve housing 40. Further, the poppet valve 42 is provided with a passage communicating the inlet chamber 43 and the slot 45. That is, the passage 52 is formed in the radial direction of the small-diameter portion 51 which always faces the inlet chamber 43, and the passage formed in the center of the passage 52 in the axial direction.
53 communicates with this passage 53, and a passage formed in the radial direction.
As shown in FIG. 1 (B), an elongate hole-shaped passage 55 is communicated with an extension of the passage 54, and the passage 55 is communicated with the slot 45. At the right end of the poppet valve 42, an inlet chamber 43 is provided.
A return flow control unit 57 is provided, which can freely contact and separate from a sheet 56 formed between the outlet 56 and the outlet chamber 59 connected to the tank 15. The return flow control unit 57 has a main flow control slot 58.
Are formed. The left end face of the poppet valve 42 shown in FIG. 4A faces a spring chamber 61, and the poppet valve 42 is pressed toward the seat 56 by a coil spring 62 built in the spring chamber 61. That is, it is pressed in the closing direction. As means for controlling the opening degree of the poppet valve 42, a passage 63 is provided from the spring chamber 61 to the outlet chamber 59, and a pilot valve 64 is interposed in the passage 63. This pilot valve 64 is connected to the spring chamber 61
The pilot flow rate discharged from is controlled by an electric signal input to a solenoid 65 from a controller (not shown).
The proportional control is performed against the spring 66. Next, the operation of the conventional meter-out valve shown in FIG. 4 will be described. Return flow Q from the fluid pressure actuator 11
Is led to the inlet chamber 43 of the poppet valve 42 and the flow rate q therein
Flows into the spring chamber 61 through the opening 46 of the slot 45. The stroke control of the poppet valve 42 is achieved by controlling the opening degree of a pilot valve 64 communicating with the spring chamber 61. The flow rate passing through the pilot valve 64 is indicated by q in the figure. By controlling the stroke of the poppet valve 42, the main flow control slot 58 at the right end in the drawing is opened,
The LQ is controlled, and the main flow rate LQ indicates a situation where the pilot flow rate q at the pilot valve 64 is amplified. That is, the pilot valve 64 is
Modulation function. To explain this, a slot 45 is formed in the outer periphery of the poppet valve 42 in the axial direction, and the pressure P1 of the inlet chamber 43 is transmitted to the spring chamber 61 through the opening 46 of the slot 45, and the pilot valve 64 is During closure, the pressure P2 in the spring chamber 61 is equal to the pressure P1 in the inlet chamber. Therefore, when the pressure P3 in the outlet chamber 59 communicated with the tank line 25 is sufficiently low (when P3 is almost 0), the poppet valve 42 has a pressure receiving area A2 on the spring chamber 61 side. Since the area A3 is larger than the donut area pressure receiving area A1 on the side of the chamber 43 by the area A3, the area is pushed rightward in the drawing and is pressed by the sheet 56, and is in a closed state. Next, when the pilot valve 64 is opened and the pilot flow rate q discharged from the spring chamber 61 reaches a predetermined amount, a pressure reducing action works at the opening 46 of the slot 45, and the pressure of the spring chamber 61 is reduced. P2 is (A1 · P1 −
When the value falls below the value of (spring force of the spring 62) / A2, the poppet valve 42 moves to the left and a slot having a constant width W is formed.
The opening 46 of the opening 45 gradually increases the opening length from the initial opening length Xo to increase the opening area, so that the flow rate q increases, the pressure P2 of the spring chamber 61 increases slightly, and the poppet valve 42 increases.
Is pushed back to the right and then stops at the balance position. Further, the opening area A of the pilot valve 64
As p increases, the flow rate q increases and the poppet valve 42
Moves further to the left (stroke X), and the poppet valve 42
The opening area A _L (X) of the main flow control slot 58 gradually increases from zero, and the main flow LQ joins the pilot flow q. Next, the opening area Ap of the pilot valve 64
FIG. 5 shows a computer simulation result of a situation in which the pilot flow rate q and the main flow rate LQ increase and merge with each other when is expanded linearly with respect to the time axis. Here, assuming that P3 = 0 from the continuous equation, the equation (1) is given by: q = C.W. (X + Xo). {(2 / p). (P1-P2)} ^1/2 = C. Ap · {(2 / ρ) · (P2−P3)} ^1/2 = C · Ap · ｛(2 / ρ) · P2｝ ^1/2 where C is the flow coefficient (constant) and ρ is the working fluid ( (Hydraulic oil). Equation (2) LQ = C · A _L (X) · {(2 / ρ) · (P 1 −P 3)} ^1/2 = C · A _L (X) · ｛(2 / ρ) · P 1 Since｝ ^1/2 Xo is usually small, if Xo = 0 is assumed in equation (1), then (W · X) ² · (P 1 −P ² ) = Ap ² · P ² , then equation (3) P 2 = ( W · X) ² · P 1 / {Ap ² + (W · X) ² } From equation (1) and equation (3), equation (4) q = C · Ap · W · X · ｛Ap ² + (W · X) ² ｝ ^-1 / ² · ｛(2 / ρ) · P1｝ ^{1/2 From} equations (2) and (4), LQ / q = A _L (X) ·) Ap ² + (W · X) ² ｝ ^1/2 / (Ap
· W · X) Now, assuming that A _L (X) = αX, (α is a constant), Equation (5) LQ / q = (α / W) ｛{1+ (W ・ X / Ap) 2｝ 1 / 2 holds. As shown by the above equation (5), when the width W of the slot 45 is small, the LQ / q value increases, and the gain of the main flow rate with respect to the pilot flow rate increases. As shown in the computer simulation result of No. 5, the gain at the time of merging the main flow rates is also increased, and a clear inflection point Pc is generated in the combined flow rate Q, resulting in poor operability. When the fixed width W of the slot 45 is increased, the gain of the main flow rate is reduced, but the pilot flow rate is excessively increased, so that the pressure loss at the pilot valve 64 is increased and the pressure P2 of the spring chamber 61 is reduced. There is a defect that the poppet valve 42 does not fully open and does not fully open. The present invention has been made in view of the above points, and in a valve device having a pilot flow rate amplification type poppet valve for controlling a main flow rate by a pilot flow rate, the operability at the time when the main flow rate is merged is improved. The purpose of the present invention is to prevent a defect that the poppet valve does not fully open. According to the first aspect of the present invention, there is provided a valve housing, and a pilot flow amplification type poppet which is slidably fitted to the valve housing and controls a main flow by a pilot flow. A valve, a sheet to which the poppet valve is brought into contact with and separated from, an inlet chamber formed on the upstream side of the sheet, an outlet chamber for the main flow discharged through the sheet, and an outlet chamber formed on the opposite side via the poppet valve A spring chamber, a spring provided in the spring chamber for pressing the poppet valve toward the seat side, and an opening provided in the outer peripheral surface of the poppet valve and communicating with the inlet chamber and opening to the spring chamber by movement of the poppet valve. A slot having a variable area, and a pilot valve for controlling a pilot flow discharged from the spring chamber and merged with the main flow, the slot includes: When the poppet valve is in contact with the seat, the slot width at the opening is large and the slot width is narrow as the poppet valve moves, and the small width at which the slot width at the opening is constant after the intermediate stroke of the poppet valve A valve device having a fixed small width portion processed so as to be as follows. At the start of opening when the poppet valve starts moving away from the seat, since the slot width at the opening is large due to the variable width portion, the gain of the main flow at the start of opening is reduced, and The gain is also low, and the change in the combined flow rate is very smooth, so that the operability is good.
During the movement of the poppet valve, the slot width gradually changes from a large value to a small value from the variable width portion to the constant small width portion, so that the integrated slot opening area does not become too large, and the pilot flow rate also increases. It is not excessive, the pressure loss at the pilot valve is not high, and the pressure in the spring chamber is sufficiently reduced, so that the defect that the poppet valve does not fully open does not occur. An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1A shows the meter-out valve 23.
Or 24 (FIG. 3), which shows the internal structure of a pilot flow amplification type poppet valve device that controls the main flow by the pilot flow, that is, a flow amplification poppet valve device, and a valve fitting hole formed in the valve housing 40. A poppet valve 42 as a movable valve body is displaceably fitted to 41, and an inlet chamber 43 formed to have a larger diameter than the valve fitting hole 41.
In addition, a meter-out passage, that is, a return passage 37 from the fluid pressure actuator 11 (FIG. 3) is connected to the meter-out passage. A large-diameter pilot control unit 44 is formed at the left end of the poppet valve 42, and a pilot flow control slot 45 is formed in the outer peripheral surface of the pilot control unit 44 in the axial direction. A part of the slot 45 is open to a spring chamber 61 described later even when the poppet valve 42 is fully closed, and the area of the opening 46 varies depending on the stroke position of the poppet valve 42. The poppet valve 42 is provided with a small-diameter portion 51 facing the inlet chamber 43 with respect to a large-diameter portion 47 fitted in the valve fitting hole 41 of the valve housing 40. Further, the poppet valve 42 is provided with a passage communicating the inlet chamber 43 and the slot 45. That is, the passage 52 is formed in the radial direction of the small-diameter portion 51 which always faces the inlet chamber 43, and the passage formed in the center of the passage 52 in the axial direction.
53 communicates with this passage 53, and a passage formed in the radial direction.
As shown in FIG. 1 (B), an elongate hole-shaped passage 55 is communicated with an extension of the passage 54, and the passage 55 is communicated with the slot 45. At the right end of the poppet valve 42, there is provided a return flow control unit 57 that can freely contact and separate from a seat 56 formed in the valve housing 40.
A main flow control slot 58 is formed in 57. The sheet 56 defines the inlet chamber 43 formed on the upstream side of the sheet 56, and the outlet chamber 59 communicated with the tank 15 via the tank line 25. The slot 45 of the poppet valve 42 is
As shown in (B), when the poppet valve 42 is not opened when it comes into contact with the seat 56, the slot width W (X) in the opening 46 is set.
And the variable width portion 45a in which the slot width W (X) gradually narrows as the stroke X increases as the poppet valve 42 moves to the left and the stroke X increases, and is processed so as to have a constant small width after the intermediate stroke. The constant small width portion 45b is formed continuously. A spring chamber 61 is formed on the opposite side of the outlet chamber 59 via the poppet valve 42, as shown in FIG.
The left end face of the poppet valve 42 shown in
The poppet valve 42 is pressed in a direction in which the poppet valve 42 comes into close contact with the seat 56, that is, in a closing direction, by a coil spring 62 serving as a spring built in the spring chamber 61. As means for controlling the opening of the poppet valve 42, a passage 63 is provided from the spring chamber 61 to the outlet chamber 59, and a pilot valve 64 is interposed in the passage 63. The pilot valve 64 is for proportionally controlling the pilot flow rate discharged from the spring chamber 61 against the spring 66 by an electric signal input from a controller (not shown) to the solenoid 65. Next, the operation of the valve device shown in FIG. 1 will be described. In the above poppet type flow control valve, the large diameter portion 47 of the poppet valve 42 and the seat
The pressure P1 of the inlet chamber 43 in the left direction in the drawing acts on the donut area pressure receiving area A1 between the pressure chamber 56 and the pressure chamber A56. At this time, the inlet chamber 43 is a passage for the poppet valve 42.
Since the pilot chamber 64 is in communication with the spring chamber 61 through the slots 52 and 53, 54, 55, the slot 45 and the opening 46, the pressure P2 of the spring chamber 61 is equal to the pressure P1 of the inlet chamber 43 while the pilot valve 64 is closed. Therefore, the pressure receiving area A2 of the poppet valve 42 on the spring chamber 61 side is also equal to the pressure P of the inlet chamber 43.
1 acts to the right in the figure, the pressure receiving area A2 is larger than the pressure receiving area A1 by the area A3, and the outlet chamber 59
Since the pressure P3 is connected to the tank line 25 and is sufficiently low, the poppet valve 42 is pushed rightward in the figure to be in close contact with the seat 56, and is in a closed state. Next, when the pilot valve 64 opens in response to the electric signal and the pilot flow q flowing out of the spring chamber 61 via the passage 63 reaches a predetermined amount, a pressure reducing action is effected at the opening 46 of the slot 45. , Spring chamber 61 pressure P2
Is less than the value of (A1 · P1−spring force of spring 62) / A2, the poppet valve 42 moves to the left,
Since the opening area of the slot 45 increases, the flow rate q increases, the pressure P2 slightly increases, and the poppet valve 42 is slightly pushed back to the right, and stops at the balance position. Further, as the opening degree of the pilot valve 64 is increased, the flow rate q increases, the poppet valve 42 further moves to the left, and the main flow rate control section 57 provided in the return flow rate control section 57 at the tip end. The opening of the slot 58 also gradually increases. When the poppet valve 42 moves to the left, the width W (X) of the slot 45 gradually changes from a large value to a small value in the variable width portion 45a. As shown in (5), since the width W (X) of the slot 45 is large at the start of opening, the LQ / q value becomes small, the gain of the main flow with respect to the pilot flow becomes low, and the computer simulation results shown in FIG. As shown in
The gain at the time when the main flow rates merge is also low, and the change in the combined flow rate Q becomes very smooth, so that the fluid pressure actuator 11 can be operated smoothly, and the operability is good. In the course of the movement of the poppet valve 42, the width W (X) of the slot 45 gradually changes from a large value to a small value from the variable width portion 45a to the fixed small width portion 45b. The slot opening area is not too large, the pilot flow is not too large, and the pilot valve 64
Is not high, and the pressure in the spring chamber 61 is sufficiently reduced, so that the defect that the poppet valve 42 does not fully open does not occur. According to the present invention, at the start of opening when the poppet valve starts moving away from the seat, the slot width at the opening is large due to the variable width portion, so that the gain of the main flow rate at the start of opening is increased. , The gain at the time when the main flow rate merges with the pilot flow rate also becomes low, and the change in the combined flow rate becomes very smooth, so that the operability can be improved. During the movement of the poppet valve, the slot width gradually changes from a large value to a small value from the variable width portion to the constant small width portion, so that the integrated slot opening area does not become too large, and the pilot flow rate also increases. It is not excessive, the pressure loss at the pilot valve is not high, and the pressure in the spring chamber is sufficiently reduced, so that a defect that the poppet valve does not fully open can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (A) is a sectional view showing an embodiment of a valve device according to the present invention, and FIG. 1 (B) is a plan view of a part of the poppet valve. FIG. 2 is a characteristic diagram showing computer simulation results of a pilot flow rate, a main flow rate, and a combined flow rate in the valve device. FIG. 3 is a circuit diagram showing a meter-in / meter-out separated control circuit. 4A is a sectional view showing a conventional poppet type flow control valve, and FIG. 4B is a plan view of a part of the poppet valve. FIG. 5 is a characteristic diagram showing computer simulation results of a pilot flow rate, a main flow rate, and a combined flow rate in the flow control valve shown in FIG. [Description of Signs] 40 Valve housing 42 Poppet valve 43 Inlet chamber 45 Slot 45a Variable width section 45b Constant small width section 46 Opening 56 Seat 59 Outlet chamber 61 Spring chamber 62 Coil spring as spring 64 Pilot valve

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16K 3/26 F16K 31/124 F16K 1/38

Claims (1)

(57) [Claim 1] A valve housing, a pilot flow amplification type poppet valve which is slidably fitted to the valve housing and controls a main flow by a pilot flow, and a poppet valve is connected and disconnected. Sheet, an inlet chamber formed on the upstream side of the sheet, an outlet chamber for main flow discharged through the sheet, a spring chamber formed on the opposite side of the outlet chamber via a poppet valve, and a spring chamber. A spring provided on the outer surface of the poppet valve for pressing the poppet valve toward the seat; a slot provided on the outer peripheral surface of the poppet valve and communicating with the inlet chamber to change an opening area of an opening portion opened to the spring chamber by movement of the poppet valve; A pilot valve for controlling a pilot flow discharged from the chamber and merged with the main flow, wherein the slot has a poppet valve in contact with the seat. In the state, the slot width in the opening is large and the slot width is narrowed as the poppet valve moves, and the slot width in the opening is processed to be a constant small width after the middle stroke of the poppet valve. A valve device having a fixed small width portion.