Fluid Control Device

Abstract

Provided is a fluid control device which prevents fluid leakage from an inlet chamber to an outlet chamber and also exhibits better control responsiveness.　A normally-closed type fluid control device (1) comprises a housing (101) including an inlet chamber (123) and an outlet chamber (122) divided by a housing land section (101B) extending radially inwards, a spool (102) disposed in the housing (101) and including a spool land section (102B) formed thereon so as to extend radially outwards and so as to be slidable back and forth on the housing land section (101B), and a biasing means (106) for biasing the spool (102) towards a valve closing position, wherein the spool (102) is displaced by an externally applied actuation force against the biasing force of the biasing means (106) so as to put the inlet chamber (123) in communication with the outlet chamber (122), the spool (102) includes an enlarged section (131) positioned in the inlet chamber (123) and having a larger diameter than that of the spool land section (102B), and the enlarged section (131) and the housing land section (101B) define a poppet valve configuration (130).

Description

[Technical Field]

[0001] The present invention relates to a fluid control device that switches the open / closed state of a flow path, and more particularly to a fluid control device that controls the flow rate of a pressurized fluid accumulated in an accumulator. [Background technology]

[0002] Conventionally, fluid circuits have been used to drive vehicles, construction machinery, industrial machinery, etc. by flowing pressurized fluid such as oil from a main pump into an actuator to drive a load. These fluid circuits are equipped with an accumulator that stores a portion of the return fluid from the actuator, and a fluid control device that switches between an open and closed state of the accumulator and an outlet-side flow path of the main pump. By closing the fluid control device, a portion of the return fluid is stored in the accumulator, and by opening the fluid control device, the pressurized fluid stored in the accumulator is regenerated in the outlet-side flow path of the main pump, thereby improving energy efficiency.

[0003] The fluid control device disclosed in Patent Document 1 is a normally closed spool valve in which a spool moves within a housing due to pilot pressure from a pilot pump. Specifically, the interior of the housing is partitioned, from one end to the other, by first, second, and third land portions of the spool into a pilot chamber located at one end of the housing so as to be switchably connected to the pilot pump and the tank, an output chamber connected to the outlet-side flow path of the main pump, an input chamber connected to an accumulator, and a drain chamber located at the other end of the housing so as to be connected to the tank.

[0004] In addition, the second land portion of the spool is a valve body portion that switches the open / closed state between the input chamber and the output chamber, and a notch is provided on the outer periphery of the second land portion as an internal flow path that opens to the output chamber and is closed on the input chamber side.

[0005] In addition, a biasing means is disposed in the drain chamber to bias the spool toward the pilot chamber. When the pilot chamber is connected to the tank, the spool is biased by the biasing means, and the input chamber and the output chamber are blocked by the second land portion. On the other hand, when the pilot chamber is connected to the pilot pump, the pilot pressure from the pilot pump moves the spool toward the drain chamber against the biasing force of the biasing means, and the input chamber and the output chamber are connected through the notch in the second land portion. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2018-168914 A (page 8, Figure 5) Summary of the Invention [Problem to be solved by the invention]

[0007] In Patent Document 1, when the input chamber and the output chamber are closed, the dimension from the outer peripheral surface of the second land portion, i.e., the closed end of the notch, to the input chamber is made sufficiently long to prevent the pressurized fluid stored in the accumulator from leaking from the input chamber to the output chamber. However, because the dimension from the closed end of the notch to the input chamber is long, it takes time for the input chamber and the output chamber to communicate through the notch, which could result in poor control responsiveness.

[0008] The present invention has been made in view of these problems, and has as its object to provide a fluid control device that prevents fluid leakage from the input chamber to the output chamber and has good control response. [Means for solving the problem]

[0009] In order to solve the above problems, the fluid control device of the present invention comprises: a housing divided into an input chamber and an output chamber by a housing land portion extending radially inward; a spool disposed within the housing, the spool having a spool land portion extending radially outward and capable of sliding reciprocally along the housing land portion; and a biasing means for biasing the spool to a valve-closed position, A normally closed type fluid control device in which the spool receives an external driving force and moves against the biasing force of the biasing means, thereby connecting the input chamber and the output chamber, The spool is disposed in the input chamber and has a large diameter portion having a diameter larger than that of the spool land portion, The large diameter portion and the housing land portion form a poppet valve structure. With this, when the valve is closed and no external driving force is applied, the spool valve is closed by the housing land and spool land, and the poppet valve consisting of the large diameter portion and land reliably seals the space between the input chamber and the output chamber. By shortening the spool land, the input chamber and the output chamber are quickly connected when the spool is moved by external driving force. This improves the control response of the fluid control device.

[0010] The large diameter portion may have a tapered shape that abuts against an opening edge of the housing land portion, and a constricted portion having a smaller diameter than the spool land portion may be formed between the large diameter portion and the spool land portion. This allows the tapered large diameter portion to be securely seated on the opening edge of the housing land, since the constricted portion extends inward beyond the spool land. Furthermore, manufacturing is simple because no special processing is required on the housing.

[0011] The spool may have a pressure-receiving surface in the large diameter portion that has an axial area equal to that of the outer diameter portion of the opening edge of the housing land portion, and that receives a force in a closing direction from the fluid that balances a force in an opening direction generated by the fluid in the input chamber acting on the outer diameter portion. As a result, the axial area of ​​the pressure-receiving surface and the outer diameter portion are the same, so the pressure-receiving surface balances the forces in the opening and closing directions acting on the spool, allowing the spool to accurately control the opening and closing of the input chamber and output chamber.

[0012] a recessed portion is provided inside the large diameter portion, the recessed portion communicating with a space on the opposite side of the input chamber from the housing land portion; and a communication hole is provided in the spool, the communication hole communicating the space within the recessed portion with the input chamber. the pressure-receiving surface is provided in the recess, and a pressure-receiving body is arranged slidably relative to the recess to hermetically separate a space within the recess from a space on the opposite side of the housing land portion, The large diameter portion may be slidable relative to the housing. With this, the large diameter portion is slidable relative to the housing, so that the poppet valve structure can be configured with a simple structure and the reciprocating movement of the spool is stabilized.

[0013] The pressure-receiving body may be separate from the housing. This simplifies the assembly work since precision is not required when assembling the fluid control device. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is an explanatory diagram showing an example of a hydraulic circuit in which a fluid control device according to a first embodiment of the present invention is used. [Figure 2] FIG. 4 is an explanatory diagram showing the relationship between the lever operation amount and the secondary pressure of the hydraulic remote control valve. [Figure 3] FIG. 3 is a cross-sectional view showing a valve-closed state of the fluid control device. [Figure 4] This is a cross-sectional view taken along the line AA. Note that only the spool is shown here. [Figure 5] 4A and 4B are explanatory diagrams showing the relationship between forces acting on the spool in the valve closing direction and the valve opening direction. [Figure 6] FIG. 1 is a cross-sectional view showing a valve open state of a fluid control device; [Figure 7]FIG. 3 is an explanatory diagram showing the relationship between a spool stroke and a spool opening degree of the fluid control device. [Figure 8] FIG. 5 is a cross-sectional view showing a fluid control device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fluid control device according to an embodiment of the present invention will be described below with reference to the accompanying drawings. [Example]

[0016] A fluid control device according to a first embodiment will be described with reference to FIGS. 1 to 7, taking as an example a form of a spool type flow control valve 1 used in a hydraulic circuit of a shovel loader.

[0017] As shown in FIG. 1, the shovel loader has a lift arm W linked to a bucket that contains earth and sand, a hydraulic cylinder 6 that serves as an actuator for driving the lift arm W, and a hydraulic circuit C that is used for the hydraulic cylinder 6.

[0018] The hydraulic circuit C mainly comprises a variable displacement hydraulic pump 3 and a fixed displacement hydraulic pump 4 (hereinafter sometimes referred to as hydraulic pumps 3, 4) driven by a drive mechanism 2 such as an engine or an electric motor, a directional control valve 5 that switches the supply destination of pressurized oil as pressurized fluid supplied from the hydraulic pump 3, a hydraulic cylinder 6 connected to the directional control valve 5, an accumulator 7 that accumulates a portion of the return oil from the hydraulic cylinder 6, an electromagnetic directional control valve 8 that switches the open / close state of an oil passage connecting the hydraulic cylinder 6 and the accumulator 7, a spool type flow control valve 1 that switches the open / close state of an oil passage 21 on the outlet side of the accumulator 7 and the hydraulic pump 3, a hydraulic remote control valve 9 that switches the supply destination of pressurized oil supplied from the hydraulic pump 4, an electromagnetic proportional valve 10 that switches the open / close state of an oil passage connecting the hydraulic pump 4 and the spool type flow control valve 1, and a controller 11 that controls the electromagnetic proportional valve 10 and the electromagnetic directional control valve 8.

[0019] The hydraulic pump 3 and the hydraulic pump 4 are connected to the drive mechanism 2 and are rotated by the power from the drive mechanism 2 to supply pressure oil downstream.

[0020] The pressure oil discharged from the hydraulic pump 3 flows through an oil passage 21 toward the directional control valve 5 .

[0021] The directional control valve 5 is a 6-port, 3-position open-center type switching valve that can be switched to a neutral position 5A, an extension position 5B, or a retraction position 5C. The flow of pressure oil in each position of the directional control valve 5 will be described in detail later.

[0022] A relief valve 14 is installed in oil passage 21 on the outlet side of hydraulic pump 3, and a portion of the pressurized oil is discharged to tank 12 through oil passage 22. The relief valve 14 prevents damage to the hydraulic equipment in the circuit, and operates when rod 6A in hydraulic cylinder 6 reaches the end of extension or contraction, or when a sudden load is applied to hydraulic cylinder 6, causing the oil in the circuit to become clogged and become abnormally high pressure.

[0023] The solenoid directional control valve 8 is a two-port, two-position normally closed solenoid directional control valve, and the solenoid directional control valve 8 and the hydraulic cylinder 6 are connected by an oil passage 23. When an electric signal from the controller 11 is applied to the solenoid 8a through an electric signal line 51, the solenoid directional control valve 8 opens the oil passage 23 and the downstream oil passage 35. The accumulator 7 is connected to the oil passage 35.

[0024] The spool type flow control valve 1 is disposed downstream of the oil passage 35, i.e., downstream of the accumulator 7, and is capable of opening and closing the oil passage 35 and the oil passage 24 downstream of the spool type flow control valve 1. This oil passage 24 is connected to the oil passage 21 on the outlet side of the hydraulic pump 3. The structure of the spool type flow control valve 1 will be described in detail later.

[0025] On the other hand, a portion of the pressure oil discharged from the hydraulic pump 4 is supplied to the hydraulic remote control valve 9 through an oil passage 25, and a portion of the pressure oil is supplied to the electromagnetic proportional valve 10 through an oil passage 26 branched from the oil passage 25.

[0026] The hydraulic remote control valve 9 is a variable pressure reducing valve, and by operating the lever 9a in the extension or contraction direction, reduced secondary pressure is supplied to the signal port 5a or signal port 5b of the directional control valve 5 through the signal oil passage 41 or signal oil passage 42. All of the pressure oil discharged from the hydraulic pump 4 that is not supplied to the signal ports from the hydraulic remote control valve 9 is discharged to the tank 12 through the relief valve 13 and oil passage 27.

[0027] When the lever 9a is operated in the extension or retraction direction, a secondary pressure proportional to the lever operation amount as shown in FIG. 2 is supplied to the signal port 5a or signal port 5b of the directional control valve 5, causing the directional control valve 5 to switch from the neutral position 5A to the extension position 5B or the retraction position 5C.

[0028] The solenoid proportional valve 10 is a normally closed type solenoid proportional valve, and when an electric signal from the controller 11 is applied to the solenoid 10a via the electric signal line 52, a secondary pressure proportional to the electric signal is output from the output port 10b and applied to the spool type flow control valve 1 through the oil passage 28. Furthermore, when no electric signal is applied, the output port 10b of the solenoid proportional valve 10 is connected to the tank 12 through the oil passage 29.

[0029] Next, the state when the lever 9a of the hydraulic remote control valve 9 is actually operated will be described.

[0030] When the lever 9a of the hydraulic remote control valve 9 is not operated, the directional control valve 5 is in the neutral position 5A. In this neutral position 5A, all of the pressurized oil discharged from the hydraulic pump 3 flows through the oil passage 21, the directional control valve 5, and the oil passage 30 to the tank 12.

[0031] When the lever 9a is operated in the retraction direction, the directional control valve 5 switches to the retraction position 5C. In this retraction position 5C, pressurized oil flows into the oil chamber 6a of the hydraulic cylinder 6 through the oil passage 31 branching from the oil passage 21, the directional control valve 5, and the oil passage 32, and the oil in the oil chamber 6b passes through the oil passage 33, the directional control valve 5, and the oil passage 34 and is discharged to the tank 12, causing the rod 6A of the hydraulic cylinder 6 to operate in the retraction direction.

[0032] In addition, when an electrical signal from the pressure sensor 15 installed on the signal oil passage 42 is input to the controller 11, and an arithmetic circuit previously implemented in the controller 11 inputs the electrical signal to the solenoid directional control valve 8 through the electrical signal line 51, the solenoid directional control valve 8 switches to the open state, and a portion of the return oil from the oil chamber 6b of the hydraulic cylinder 6 passes through the oil passage 23, the check valve 17, the solenoid directional control valve 8, and the oil passage 35 and is accumulated in the accumulator 7.

[0033] On the other hand, when the lever 9a is operated in the extension direction, the directional control valve 5 switches to the extension position 5B. At this extension position 5B, pressurized oil flows into the oil chamber 6b of the hydraulic cylinder 6 through the oil passage 31, the directional control valve 5, and the oil passage 33, and the oil in the oil chamber 6a passes through the oil passage 32, the directional control valve 5, and the oil passage 34 and is discharged to the tank 12, causing the rod 6A of the hydraulic cylinder 6 to operate in the extension direction.

[0034] Furthermore, when an electric signal is input from pressure sensor 16 installed on signal oil passage 41 to controller 11, and an arithmetic circuit pre-installed in controller 11 inputs the electric signal through electric signal line 52 to solenoid proportional valve 10, secondary pressure is applied to spool type flow control valve 1 through oil passage 28, and spool type flow control valve 1 opens, causing stored oil in accumulator 7 to flow through spool type flow control valve 1 and oil passage 24 to join oil passage 21 and be regenerated in oil chamber 6b of hydraulic cylinder 6.

[0035] At this time, the controller 11 also inputs an electric signal through the electric signal line 53 to the discharge oil amount control section 3a of the hydraulic pump 3, thereby reducing the pump discharge amount.

[0036] In this way, the hydraulic circuit C of pressurized oil using the accumulator 7 regenerates the pressurized oil stored in the accumulator 7, thereby reducing the amount of oil discharged from the hydraulic pump 3 while achieving a sufficient extension speed of the hydraulic cylinder 6, thereby enabling the shovel loader to save energy.

[0037] Next, the structure of the spool type flow control valve 1 will be described with reference to Figures 3 and 4. Note that Figure 3 illustrates the closed state of the spool type flow control valve 1, in which the spool 102 does not receive pressure oil, i.e., no driving force, from the hydraulic pump 4.

[0038] As shown in FIG. 3, the spool-type flow control valve 1 mainly comprises a cylindrical housing 101, a spool 102 inserted into the housing 101, sealing bodies 103 and 104 that close openings on both sides of the housing 101, a pressure-receiving body 105 that is arranged within the spool 102 so as to be able to slide relative to the pressure-receiving body 105, and a spring 106 as a biasing means that is arranged between the spool 102 and the sealing body 104.

[0039] Housing 101 is provided with a first inner diameter land portion 101A extending toward the inner diameter side from sealing body 103 toward sealing body 104, a second inner diameter land portion 101B as a housing land portion, and a third inner diameter land portion 101C spaced apart from each other.

[0040] In other words, large diameter portions 101D and 101E having a larger diameter than each of the inner diameter land portions are formed between the first inner diameter land portion 101A and the second inner diameter land portion 101B, and between the second inner diameter land portion 101B and the third inner diameter land portion 101C.

[0041] The first inner diameter land portion 101A and the second inner diameter land portion 101B have the same inner diameter, and the third inner diameter land portion 101C has a larger inner diameter than the first inner diameter land portion 101A and the second inner diameter land portion 101B.

[0042] In addition, the housing 101 is formed with a perforation 108 that radially connects the internal space of the large diameter portion 101D with the external space, a perforation 109 that radially connects the internal space of the large diameter portion 101E with the external space, and a perforation 115 that radially connects the internal space of the third inner diameter land portion 101C with the external space near the sealing body 104.

[0043] The bore 108 communicates with the regenerative oil passage 24 (see FIG. 1). That is, the bore 108 is an output port through which the stored oil in the accumulator 7 is output to the oil passage 24 from the internal space of the large diameter portion 101D.

[0044] Further, the bore 109 communicates with the oil passage 35 and the accumulator 7 (see FIG. 1). That is, the bore 109 is an input port through which the stored oil in the accumulator 7 is input into the internal space of the large diameter portion 101E.

[0045] The bore 115 also communicates with an oil passage (not shown) that communicates with the tank 12 .

[0046] On the spool 102, a first outer diameter land portion 102A, a second outer diameter land portion 102B, and a third outer diameter land portion 102C are provided in this order from the sealing body 103 toward the sealing body 104, and are spaced apart from each other.

[0047] The first inner diameter land portion 101A and the first outer diameter land portion 102A that slides thereon constitute a first sliding portion 102a.

[0048] The second inner diameter land portion 101B and the second outer diameter land portion 102B, which serves as a spool land portion that slides against the second inner diameter land portion 101B, form a second sliding portion 102b. A plurality of notches 112 extending in the axial direction are formed in the second outer diameter land portion 102B.

[0049] 4, the notch 112 has a wall portion 112a that opens to the first sliding portion 102a side and extends radially outward toward the third sliding portion 102c side. Note that only the spool 102 is shown in FIG.

[0050] Returning to FIG. 3, the third inner diameter land portion 101C and the third outer diameter land portion 102C, which serves as a large diameter portion that slides against the third inner diameter land portion 101C, form a third sliding portion 102c.

[0051] The first sliding portion 102a and the second sliding portion 102b are spaced apart in the axial direction and connected by a small diameter portion 102d (see FIG. 4) that is smaller in diameter than the first sliding portion 102a and the second sliding portion 102b. The third sliding portion 102c is formed to have a larger diameter than the first sliding portion 102a and the second sliding portion 102b.

[0052] Specifically, a tapered large diameter portion 131 is formed between the second outer diameter land portion 102B and the third outer diameter land portion 102C.

[0053] In addition, a constricted portion 111 having a smaller diameter than the second outer diameter land portion 102B is formed circumferentially between the large diameter portion 131 and the second outer diameter land portion 102B. That is, a portion of the large diameter portion 131 extends radially inward beyond the second outer diameter land portion 102B.

[0054] Furthermore, the large diameter portion 131 is adapted to abut in a sealing manner against an opening edge 132 on the large diameter portion 101E side of the second inner diameter land portion 101B when the spool type flow control valve 1 is in a closed state. In other words, the large diameter portion 131 and the opening edge 132 constitute a poppet valve 130.

[0055] Further, a recess 110 that opens into the space on the sealing body 104 side is provided inside the third sliding portion 102c. Further, the third sliding portion 102c is formed with a perforation 116 as a communication hole that radially communicates the internal space of the recess 110 with the internal space of the large diameter portion 101E. The detailed shape of the recess 110 will be described later.

[0056] A pressure receiving body 105, which is separate from the housing 101 and the sealing body 104, is disposed in the recess 110 so as to be able to slide relative to the housing 101 and the sealing body 104. Both ends of the pressure receiving body 105 are formed in a semi-spherical shape.

[0057] The sealing bodies 103 and 104 are fixed to both ends of the housing 101 by fastening members such as bolts (not shown), and sealing members 113 and 114 are arranged between the sealing bodies 103 and 104 and the housing 101, sealing the gap between the sealing bodies 103 and 104 and the housing 101.

[0058] Furthermore, a bore 103a is formed in the sealing body 103, penetrating it in the axial direction, and the bore 103a communicates with the oil passage 28 (see FIG. 1).

[0059] In the following, in the housing 101, the space sandwiched between the sealing body 103 and the first sliding portion 102a will be referred to as the oil chamber 121, the space sandwiched between the first sliding portion 102a and the second sliding portion 102b will be referred to as the oil chamber 122 serving as the output chamber, the space sandwiched between the second sliding portion 102b and the third sliding portion 102c will be referred to as the oil chamber 123 serving as the input chamber, and the space sandwiched between the third sliding portion 102c, the pressure-receiving body 105, and the sealing body 104 will be referred to as the oil chamber 124.

[0060] The space in the recess 110 that is separated from the oil chamber by the pressure-receiving body 105 is referred to as an oil chamber 125. The oil chamber 123 and the oil chamber 125 communicate with each other through a bore .

[0061] As shown in FIG. 3, when the spool type flow control valve 1 is in a closed state, the first sliding portion 102a of the spool 102 hermetically separates the oil chambers 121 and 122, and the third sliding portion 102c hermetically separates the oil chambers 123 and 124.

[0062] Specifically, the gap between the first inner diameter land portion 101A and the first outer diameter land portion 102A and the gap between the third inner diameter land portion 101C and the third outer diameter land portion 102C are small. Furthermore, the dimension S1 of the axial overlap portion between the first inner diameter land portion 101A and the first outer diameter land portion 102A and the dimension S3 of the axial overlap portion between the third inner diameter land portion 101C and the third outer diameter land portion 102C are sufficiently long, so there is almost no oil leakage from the gap between the first inner diameter land portion 101A and the first outer diameter land portion 102A and the gap between the third inner diameter land portion 101C and the third outer diameter land portion 102C. Note that the dimensions S1 and S3 may be the same or different.

[0063] The amount of oil leakage varies depending on factors such as the diameter of the land on the housing 101 side, the annular area of ​​the gap between the land on the housing 101 side and the land on the spool 102 side, the axial overlap dimension between the land on the housing 101 side and the land on the spool 102 side, and the pressure difference between adjacent oil chambers.

[0064] Furthermore, when the spool-type flow control valve 1 is in a closed state, the perforations 103a, 108, and 115 are in communication with the tank 12 (see FIG. 1), so that the oil chambers 121, 122, and 124 are at the same pressure.

[0065] Furthermore, when the spool type flow control valve 1 is in a closed state, the oil chamber 122 and the oil chamber 123 are hermetically separated by a spool valve consisting of the second inner diameter land portion 101B and the second outer diameter land portion 102B, and a poppet valve 130 consisting of a large diameter portion 131 and an opening edge 132.

[0066] Specifically, the gap between the second inner diameter land portion 101B and the second outer diameter land portion 102B is small, and the gap is blocked by a poppet valve 130 consisting of a large diameter portion 131 and an opening edge 132, so there is no oil leakage from the gap between the second inner diameter land portion 101B and the second outer diameter land portion 102B.

[0067] In this way, the space between the oil chamber 122 and the oil chamber 123 can be reliably sealed by closing the two valves, and therefore the second outer diameter land portion 102B can be formed to be short in the axial direction.

[0068] Specifically, the dimension S2 of the portion where the second inner diameter land portion 101B and the portion of the second outer diameter land portion 102B from the wall portion 112a of the notch 112 to the constricted portion 111 overlap in the axial direction (i.e., viewed radially) can be made sufficiently shorter than the dimensions S1 and S3 (S1, S3 > S2).

[0069] Furthermore, since bore 109 is connected to accumulator 7 (see FIG. 1), the pressure in oil chamber 123 is higher than the pressure in oil chambers 121, 122, and 124. Furthermore, as described above, oil chamber 123 and oil chamber 125 are connected through bore 116, so that oil chamber 123 and oil chamber 125 are at the same pressure.

[0070] Furthermore, since the pressure in the oil chamber 125 is higher than the pressure in the oil chamber 124 , the pressure-receiving body 105 is pressed against the sealing body 104 by the pressure in the oil chamber 125 .

[0071] Here, the force acting on the spool 102 when the spool type flow control valve 1 is in the closed state will be described with reference to FIG.

[0072] As shown in FIG. 5, a force R acts on the spool 102 in the valve opening direction.

[0073] Specifically, if the pressure inside the oil chamber 123 is pressure P, the pressure P acts on an area G in the axial direction of the outer diameter portion of the large diameter portion 131, which is greater than the portion that contacts the opening edge 132, i.e., the cosine area of ​​the annular inclined surface between the portion that contacts the opening edge 132 of the large diameter portion 131 and the third outer diameter land portion 102C, and the force R acting on the spool 102 in the valve opening direction is R = P × G. Note that hereinafter, the area G of the outer diameter portion in the axial direction will also be referred to as the axial view area G of the outer diameter portion.

[0074] On the other hand, a force T acts on the spool 102 in the valve closing direction.

[0075] The force T will be described in detail. The recess 110 has a small diameter recess 110A having an opening that opens into the oil chamber 124 (see FIG. 3), and a large diameter recess 110B having a larger diameter than the small diameter recess 110A and an end surface 110a. The end surface 110a has a pressure-receiving portion G' as a pressure-receiving surface to which the pressure P in the oil chamber 125 is applied.

[0076] Pressure P within oil chamber 125 is applied to the entire surface of end face 110a. The portion of end face 110a that is outer diameter than small diameter recess 110A and annular surface 110b that forms a step with small diameter recess 110A and large diameter recess 110B face each other in the axial direction and have the same area, and the forces of pressure P acting in the valve closing direction and the valve opening direction at these opposing points are offset. Therefore, the portion of end face 110a that essentially acts in the valve closing direction, i.e., the region of end face 110a excluding the portion outer diameter than small diameter recess 110A, is defined as pressure-receiving portion G'.

[0077] That is, the pressure P in the oil chamber 125 is applied to the pressure receiving portion G', and the force T acting on the spool 102 in the valve closing direction is T=P×G'.

[0078] Incidentally, the axially viewed area G of the outer diameter portion of the spool 102 and the pressure-receiving portion G' have the same area (G = G'). From the above, the force R acting on the spool 102 in the valve-opening direction and the force T acting on the spool 102 in the valve-closing direction are the same (R = T), and these forces R and T cancel each other out and are balanced.

[0079] Next, the open state of the spool type flow control valve 1 will be described with reference to FIGS.

[0080] As shown in Figure 6, when pressurized oil is supplied from hydraulic pump 4 (see white arrow in Figure 6) into oil chamber 121 through perforation 103a of sealing body 103, the spool 102 moves in the valve opening direction against the biasing force of spring 106 due to the oil pressure until end 102e of spool 102 abuts the end face of sealing body 104.

[0081] When the spool 102 moves from the valve closed position to the valve open position, the oil chambers 122 and 123 communicate with each other through a plurality of notches 112 provided on the outer peripheral surface of the second sliding portion 102b. Even when the spool 102 moves to the valve open position, the oil chambers 121 and 122 are hermetically separated by the first sliding portion 102a, and the oil chambers 123 and 124 are hermetically separated by the third sliding portion 102c.

[0082] When oil chamber 122 and oil chamber 123 are connected to each other, pressurized oil from accumulator 7, which is supplied into oil chamber 123 through perforation 109, flows into oil chamber 122 through notch 112 and then flows out of oil chamber 122 downstream through perforation 108 (see the black arrow in Figure 6).

[0083] At this time, the oil in the oil chamber 124 is discharged through the perforations 115 into the tank 12 (see FIG. 1).

[0084] Fig. 7 shows the relationship between the stroke of the spool 102 and the opening of the notch 112 (also referred to as the spool opening). In Fig. 7, the spool type flow control valve 1 of this embodiment is shown by a solid line, and the spool type flow control valve without a poppet valve is shown by a dashed line.

[0085] 7, the horizontal axis represents the stroke of the spool 102, and the vertical axis represents the opening of the notch 112. In the spool-type flow control valve 1 (solid line), the notch 112 is closed with an opening of zero from stroke 0 to stroke U. It begins to open at stroke U and reaches a maximum value Z at stroke V. The section from stroke 0 to stroke U is the stroke until the wall portion 112a of the notch 112 reaches the opening edge 132 of the second inner diameter land portion 101B (see FIG. 3).

[0086] On the other hand, a spool-type flow control valve without a poppet valve (dashed line) needs to ensure a long dimension for the portion where the housing land and spool land overlap in the axial direction to prevent oil leakage from between them, which lengthens the section from stroke 0 to stroke U' where the valve starts to open, resulting in poor control response.Furthermore, the section from stroke U' to stroke V, i.e., the control range of the flow control curve, becomes narrow, which causes the problem of poor controllability.

[0087] In other words, the spool type flow control valve 1 (solid line) can precisely control the spool opening. In other words, it has a high degree of freedom in the flow control curve. This is because, compared to a spool type flow control valve without a poppet valve (dashed line), the section from stroke 0 to stroke U can be shortened, resulting in good control response and a wide section from stroke U to stroke V.

[0088] As described above, when the spool type flow control valve 1 is in the closed state, the spool valve is closed by the second inner diameter land portion 101B and the second outer diameter land portion 102B, and the poppet valve 130 consisting of the large diameter portion 131 and the opening edge 132 can reliably seal the space between the oil chamber 122 and the oil chamber 123, so the second outer diameter land portion 102B can be made short in the axial direction. As a result, when the spool type flow control valve 1 is in the open state, the oil chamber 122 and the oil chamber 123 quickly communicate with each other, improving control response.

[0089] Furthermore, due to the small diameter constriction 111 formed between the large diameter portion 131 and the second outer diameter land portion 102B, the tapered large diameter portion 131 extends more inwardly than the second outer diameter land portion 102B, so that the large diameter portion 131 can be securely seated on the opening edge 132 of the second inner diameter land portion 101B.

[0090] Furthermore, since no special processing such as forming a tapered opening edge 132 is required, the housing 101 can be manufactured easily.

[0091] Furthermore, spool 102 has an axially viewed area G of the outer diameter portion of large diameter portion 131 to which the pressure from inside oil chamber 123 is applied, and a pressure-receiving portion G' that has the same area as area G and to which the pressure from inside oil chamber 125 is applied, so that a force R in the valve-opening direction and a force T in the valve-closing direction that are generated by the pressure being applied to area G in the axial view of the outer diameter portion and pressure-receiving portion G' cancel each other out and are balanced. This allows spool 102 to accurately control the opening and closing of oil chambers 122 and 123.

[0092] Furthermore, a pressure-receiving body 105 is disposed in a recess 110 of the spool 102, and the recess 110 and the pressure-receiving body 105 define an oil chamber 125, with the oil chamber 123 and the oil chamber 125 communicating with each other through a bore 116. Furthermore, a pressure-receiving portion G' having the same area as the axial-view area G of the outer diameter portion is provided on an end face 110a of the recess 110. This allows the oil chamber 123 and the oil chamber 125 to be at the same pressure, and the pressures of the oil chamber 123 and the oil chamber 125 are applied to the axial-view area G of the outer diameter portion and the pressure-receiving portion G', which have the same area, so that the force R in the valve-opening direction of the spool 102 and the force T in the valve-closing direction can be reliably and easily balanced.

[0093] Furthermore, since the pressure receiving body 105 is separate from the housing 101 and the sealing body 104, high precision is not required when assembling the spool type flow control valve 1, and the assembly work is simple.

[0094] Furthermore, since the third outer diameter land portion 102C, which has the same diameter as the outer diameter of the large diameter portion 131, slides against the third inner diameter land portion 101C, and the recess 110 and the pressure-receiving body 105 slide against each other, tilting of the spool 102 when it moves axially can be prevented, and the spool 102 can be moved axially stably.

[0095] Furthermore, since the third outer diameter land portion 102C extends axially from the outer diameter of the large diameter portion 131, when assembling the spool type flow control valve 1, the spool 102 can be inserted and positioned from the opening on the sealing body 104 side of the housing 101, which simplifies the assembly work, and since the housing 101 can be constructed from a single member, the manufacturing and assembly of the housing 101 is also simple.

[0096] Specifically, if only part of the spool valve were to have a poppet structure, the housing would have to be divided into multiple sections at the position of the poppet portion that forms the large diameter, which would increase the number of processes and complicate the structure. For example, if the housing were to be divided into multiple sections, the two divided housings would need to be aligned with each other, making the processing difficult. However, by providing the third outer diameter land portion 102C so that it extends axially from the outer diameter of the large diameter portion 131 as in this structure, the housing 101 can be formed as a single unit, simplifying manufacturing and processing.

[0097] In the first embodiment, the outer diameter portion and the pressure-receiving surface have the same area, and the force on both sides of the spool in the axial direction is balanced by applying the same fluid pressure to the outer diameter portion and the pressure-receiving surface. However, the present invention is not limited to this, and the force on both sides of the spool in the axial direction may be balanced by applying fluids with different pressures to the outer diameter portion and the pressure-receiving surface. In other words, the outer diameter portion and the pressure-receiving surface may have different areas.

[0098] Furthermore, in this Example 1, an example was given in which the pressure-receiving surface G' is provided on the end face 110a of the recess 110, but this is not limited to this and the pressure-receiving surface can be freely changed as long as it is axially opposite the outer diameter portion of the large diameter portion and is subjected to fluid pressure in the valve closing direction.

[0099] Furthermore, in the first embodiment, the housing 101 and the sealing member 104 are separate bodies, but this is not limiting. For example, the housing 101 and the sealing member 104 may be integrally formed as a part extending from the housing 101 or the sealing member 104. [Example]

[0100] Next, a fluid control device according to a second embodiment will be described with reference to Fig. 8. Note that a description of the same configuration as in the first embodiment will be omitted.

[0101] As shown in FIG. 8, the spool type flow control valve 200 mainly includes a housing 201, a spool 202, sealing bodies 203 and 204, and a spring 206.

[0102] The housing 201 is provided with a first inner diameter land portion 201A and a second inner diameter land portion 201B as a housing land portion, which are spaced apart from each other. A large diameter portion 201D is formed between the first inner diameter land portion 201A and the second inner diameter land portion 201B. A large diameter recess 201E that opens toward the sealing body 204 is formed on the second inner diameter land portion 201B on the sealing body 204 side. The housing 201 is also provided with a bore 208 that communicates with the regenerative oil passage 24 (see FIG. 1) and a bore 209 that communicates with the accumulator 7.

[0103] Sealing body 204 has a U-shaped cross section, and the inner circumferential surface of the recess that opens toward housing 201 forms third inner diameter land portion 201C. Third inner diameter land portion 201C is formed to have the same diameter as first inner diameter land portion 201A and second inner diameter land portion 201B. Sealing body 204 also has perforation 215 formed therein that communicates with tank 12 (see FIG. 1).

[0104] A first sliding portion 202a, a second sliding portion 202b, and a third sliding portion 202c are provided on the spool 202. The first sliding portion 202a, the second sliding portion 202b, and the third sliding portion 202c have the same diameter.

[0105] A large diameter portion 231 is formed on the second sliding portion 202b on the sealing body 204 side. The large diameter portion 231 is axially separated from the third sliding portion 202c, and the large diameter portion 231 and the third sliding portion 202c are connected by a small diameter portion 202e having a smaller diameter than the third sliding portion 202c.

[0106] The large diameter portion 231 and the opening edge 232 constitute a poppet valve 230 .

[0107] When pressure oil is supplied from hydraulic pump 4 (see FIG. 1) into oil chamber 221 through bore 203a, spool 202 moves in the valve opening direction against the biasing force of spring 206 until the end of third sliding portion 202c abuts against the end of sealing body 204. In this state, oil chambers 222 and 223 communicate with each other through notch 212.

[0108] In this way, when the spool type flow control valve 200 is in a closed state, in addition to the spool valve being blocked by the second inner diameter land portion 201B and the second outer diameter land portion 202B, the poppet valve 230 formed by the large diameter portion 231 and the opening edge 232 can reliably seal the space between the oil chamber 222 and the oil chamber 223, so the second outer diameter land portion 202B can be formed short in the axial direction.

[0109] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes modifications and additions that do not deviate from the gist of the present invention.

[0110] For example, in the above embodiment, a hydraulic circuit was described in which a portion of the return oil is stored in an accumulator when the hydraulic cylinder retracts and the stored oil is regenerated when the hydraulic cylinder extends. However, for example, it is also possible to store pressure in the accumulator when the hydraulic cylinder extends and regenerate the stored oil when the hydraulic cylinder retracts. Also, it is possible to store a portion of the return oil generated when another actuator is driven in an accumulator and regenerate the stored oil in the hydraulic cylinder. In other words, the present invention is applicable to various fluid circuits that use an accumulator for storage and regeneration.

[0111] Furthermore, the fluid control device is not limited to use in the hydraulic circuit of a shovel loader, but may be applied to the fluid circuits of vehicles other than shovel loaders, construction machinery, industrial machinery, etc. Furthermore, the pressure fluid used in the fluid circuit may be a liquid or gas other than oil.

[0112] Furthermore, the fluid control device in the above embodiment is exemplified as a form in which the valve is switched between a closed state and an open state by pilot oil pressure from a hydraulic pump, but this is not limiting, and a spool-type solenoid valve may also be used. [Explanation of symbols]

[0113] 1. Spool-type flow control valve (fluid control device) 3,4 Hydraulic pump 5-way valve 6 Hydraulic cylinder (actuator) 7 Accumulator 21~35 Oil road 101 Housing 101B Second inner diameter land (housing land) 102 spool 102B Second outer diameter land (spool land) 102C Third outer diameter land (large diameter part) 103,104 Sealing body 105 Pressure receiving body 106 Spring (biasing means) 110 recess 111 Neck 112 notches 116 Perforation (communication hole) 122 Oil chamber (output chamber) 123 Oil chamber (input chamber) 125 Oil chamber (space inside the recess) 130 Poppet valve 131 Large diameter section 132 Opening edge 200 Spool-type flow control valve (fluid control device) 230 Poppet valve 231 Large diameter section 232 Opening edge C Hydraulic circuit G Axial area of ​​outer diameter G' Pressure receiving part (pressure receiving surface)

Claims

1. a housing divided into an input chamber and an output chamber by a housing land portion extending radially inward; a spool disposed within the housing, the spool having a spool land portion extending radially outward and capable of sliding reciprocally along the housing land portion; and a biasing means for biasing the spool to a valve-closed position, A normally closed type fluid control device in which the spool receives an external driving force and moves against the biasing force of the biasing means, thereby connecting the input chamber and the output chamber, The spool is disposed in the input chamber and has a large diameter portion having a diameter larger than that of the spool land portion, The large diameter portion and the housing land portion form a poppet valve structure, The large diameter portion is formed in a tapered shape, a constricted portion having a smaller diameter than the spool land portion is formed between the large diameter portion and the spool land portion of the spool, one surface of the constricted portion is defined by a tapered surface that is continuous with the large diameter portion, a pressure-receiving surface in the large diameter portion of the spool that is equal to the axial area of ​​the outer diameter portion of the spool relative to the opening edge of the housing land portion and that receives a force from the fluid in the input chamber in a closing direction that balances the force in the opening direction acting on the outer diameter portion.

2. a recessed portion is provided inside the large diameter portion, the recessed portion communicating with a space on the opposite side of the input chamber from the housing land portion; and a communication hole is provided in the spool, the communication hole communicating the space within the recessed portion with the input chamber. the pressure-receiving surface is provided in the recess, and a pressure-receiving body is arranged slidably relative to the recess to hermetically separate a space within the recess from a space on the opposite side of the housing land portion, 2. The fluid control device according to claim 1, wherein the large diameter portion is slidable relative to the housing.

3. 3. The fluid control device according to claim 2, wherein the pressure receiving body is separate from the housing.

Images