CN1587719A - Pilot type pure water overflow valve - Google Patents

Pilot type pure water overflow valve Download PDF

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Publication number
CN1587719A
CN1587719A CN 200410053555 CN200410053555A CN1587719A CN 1587719 A CN1587719 A CN 1587719A CN 200410053555 CN200410053555 CN 200410053555 CN 200410053555 A CN200410053555 A CN 200410053555A CN 1587719 A CN1587719 A CN 1587719A
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China
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valve
guide
hole
main
main valve
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CN 200410053555
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Chinese (zh)
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CN1304761C (en
Inventor
杨华勇
弓永军
周华
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Zhejiang University ZJU
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Zhejiang University ZJU
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Priority to CNB2004100535559A priority Critical patent/CN1304761C/en
Publication of CN1587719A publication Critical patent/CN1587719A/en
Application granted granted Critical
Publication of CN1304761C publication Critical patent/CN1304761C/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Abstract

The invention discloses a kind of pure water overflow valve. In the king valve there is a king valve cover inside which there is a king valve core held down by a spring; on the bottom of the king valve body there is water inlet and outlet connected by the king valve's channel; The king valve plug having a secondary throttling cone valve structure with high pressure conduction reduce noise and abate vibration, and the constant liquid damp installed in the king valve core confirm the working stability of the overflow valve; the guide valve having cone valve structure with damping piston don't only increase motion damp to advance the working stability of the overflow valve, but also make the guide valve core conduct so as to confirm that it don't bank after being opened; constant liquid damp is set at the entrance of the guide valve so as to increase constant pressure precision of the overflow valve. The invention achieves zero leakage by sealing directly valve plug and valve cover, valve cover and valve body, and improve static performance of the overflow valve by add valve port damper; the valve is versatile.

Description

Pilot-operated water hydraulic relief valve
Technical field
The present invention relates to the hydraulic control technology is the hydraulic element of feature, relates in particular to a kind of pilot-operated water hydraulic relief valve.
Background technique
The pure water hydraulics technology has the unique advantage of the feature of environmental protection and flame retarding because of it, just be subjected to the extensive attention of countries in the world hydraulic pressure circle, and water hydraulic components also becomes one of key content of research.Relief valve is one of the most key valve element of hydraulic system, also becomes research emphasis at the research of the relief valve that is applicable to the pure water hydraulics system.
Traditional oil pressure relief valve has two kinds of patterns: a kind of direct acting type relief valve of forming by valve body, taper or spherical valve core and pressure adjusting spring, also claim direct-acting overflow valve, and its pressure controling precision is low, often does pilot valve and uses; Another kind is by pilot valve and two-stage or three grades of pilot operated compound relief valves that concentric main valve is formed, and this valve allows pressure to be carried out minor adjustments, the pressure controling precision height.But, because the spool of pilot valve is taper or sphere, no matter be direct-acting type or leading type, because the settable orifice of its pilot valve has only one, and opening degree is very little, the flow gain height, and noise is big, thereby limited its working pressure can not be too high, valve easily breaks, the life-span is short.In the pure water hydraulics system, because the density of water is big, viscosity is little, the working stability problem of water hydraulic relief valve is even more serious than oil pressure relief valve, simultaneously, the leakage rate of water hydraulic relief valve is tens of times of oil pressure relief valve under the same conditions, makes the structure of existing oil pressure relief valve can't be applicable to aqueous medium.
In addition, because the pressure for vaporization height of water make water electrode easily vaporize and boiling, thereby under the same conditions, the cavitation erosion degree that water hydraulic relief valve suffers is than the strong hundreds of times of oil pressure relief valve; Compare with mineral oil, aqueous medium corrosivity is very strong, and the destruction of corrosive action makes prior oil pressure relief valve material all not be suitable for aqueous medium.
Therefore, how to draw the design experiences of traditional oils pressurized overflow valve, overcome the adverse effect that aqueous medium brings, improve the quiet dynamic characteristic of relief valve, become the key point of water hydraulic relief valve research.The water hydraulic relief valve structure of development has mainly still been continued to use traditional oil pressure structure of relief valve in the world at present, it has only a fixer resistance in the guide loop, between poppet valve core and valve seat, form variable liquid resistance, when spillway discharge increases, pilot valve and main valve aperture all will increase, flow increases, and inlet pressure increases, and therefore has bigger positive stable state override pressure.And its anti-cavitation erosion ability is relatively poor, and to having relatively high expectations of processing technology, processing cost is higher.
Summary of the invention
The object of the present invention is to provide a kind of pilot-operated water hydraulic relief valve, be used to improve the quiet dynamic characteristic of relief valve, realize not having and leak, alleviate phenomenons such as cavitation erosion, corrosion simultaneously, be higher than in being applicable under the aqueous medium environment.
The technical solution adopted for the present invention to solve the technical problems is: comprise that pilot-operated water hydraulic relief valve is combined by main valve and pilot valve arranged coaxial; Wherein:
1) main valve: comprise main valve body, be contained in the main valve housing in the main valve body opening, main valve plug is contained in the main valve housing, the resistance of main valve liquid is housed in the main valve plug small through hole, in the main valve plug large through-hole main spool spring is housed, when main valve plug is opened, form the variable restrictor valve port of two polyphones between main valve plug and the main valve housing, have water intake and water outlet on the main valve body, the liquid flow point of water intake is a two-way, lead up to the main valve plug center hole, main valve liquid resistance is communicated with the main spool spring chamber, and another road is communicated with water outlet by the runner that forms between main valve plug and the main valve housing, has radial direction through hole in the main valve plug center hole;
2) pilot valve: comprise guide's valve body, have six stepped hole in guide's valve body from left to right successively, guide's valve body from left to right first, two, guide's valve pocket is housed in three holes, be contained in the guide's spool in the pilot valve trepanning, the resistance of pilot valve liquid is housed in the 4th hole, the other end of main valve housing matches with the 6th hole in guide's valve body, the other end of main spool spring withstands on the 5th hole end surface in guide's valve body, in first hole of guide's valve body the pilot valve end cap is housed, the pilot valve end cap, in adjustable lever is housed, the pilot valve spring withstands between guide's spool and the adjustable lever, the liquid stream in main spool spring chamber is through the 6th hole of guide's valve body, the 5th hole, the resistance of pilot valve liquid enters the 3rd hole, the radial direction through hole that puts through pilot valve enters pilot valve and puts center hole then, when guide valve core is opened in the ban, form a variable restrictor valve port between guide's spool and the guide's valve pocket, the liquid stream that pilot valve puts in the center hole flows in guide's valve body first hole through settable orifice and guide's valve pocket radial direction through hole, the inclined hole that liquid stream in the pilot valve spring chamber puts by pilot valve flows in guide's valve body first hole, and liquid stream is communicated with the main valve water outlet by the runner on guide's valve body in guide's valve body first hole;
With the O-ring seals sealing, respectively with the O-ring seals sealing, use O-ring seals, sealing between the 6th hole of main valve housing and guide's valve body between main valve housing and the main valve body between main valve plug and the main valve housing; Seal with O-ring seals between guide's valve pocket and the guide's valve body; With the O-ring seals sealing, seal with O-ring seals between adjustable lever and the pilot valve end cap between pilot valve end cap and the guide's valve body.
Main valve plug is the two-step throttle structure that has effective inhibition cavitation erosion, reduces noise, reduces to vibrate, and have at the main valve plug center and can influence the high-pressure induct of main flow bundle radial direction through hole, set up the pilot valve liquid resistance that can improve the relief valve setting-pressure accuracy in the pilot valve ingress, resistance of main valve liquid and pilot valve liquid resistance polyphone, guide's spool be for increasing kinetic damping, improve the relief valve working stability, make guide's spool guiding, three grades of cone valve structures of band damping piston that can canting after guaranteeing to open.
The present invention compares with background technique, and the beneficial effect that has is:
1, main valve plug is the variable restrictor valve port that forms two polyphones between two-step throttle structure and the main valve housing, the pressure drop of relief valve in main valve born by two settable orifices, thereby improved the relief valve working pressure, so, for reaching same pressure regulation requirement, need by same flow, opening degree must increase, because opening degree increases, flow gain reduces, thereby has improved relief valve stability; In addition, have the high-pressure induct hole at the center, utilize the high-pressure induct bundle to influence the main flow bundle, can effectively suppress cavitation erosion, reduce noise, reduce vibration;
2, set up the liquid resistance in the pilot valve ingress, make and not only can improve resistance of main valve liquid and first drain resistance polyphone the relief valve setting-pressure accuracy, and can avoid elongated hole liquid capacitance-resistance to be prone to blocking problem; Guide's spool is the cone valve structure of band damping piston, thereby this piston can not only increase the working stability that kinetic damping improves relief valve, can also make guide's spool guiding, can canting after guaranteeing to open;
3, between main valve plug and the main valve housing, between main valve housing and the main valve body, between main valve housing and the guide's valve body, between guide's valve pocket and the guide's valve body, between pilot valve end cap and the guide's valve body, all directly seal between adjustable lever and the pilot valve end cap, efficiently solve water hydraulic relief valve and leak serious problem with O-ring seals;
4, the main valve inner flow passage of particular design and valve pocket structure help alleviating the harm that cavitation erosion brings.For preventing cavitation erosion, utilize flow field simulation that the main valve inner flow passage has been carried out optimal design, can make current smooth more, alleviated cavitation erosion and flow noise, all elements of valve are equal to adopt anti-corrosion non-corrosive material, can guarantee that valve has the long life-span;
5, simple structure of the present invention, flexible movements are reliable, and it is good to have versatility, is easy to standardized characteristics, is applicable to the mesohigh operating conditions.
Description of drawings
Fig. 1 is a structural principle schematic representation of the present invention.
Fig. 1: the 1st, main valve body, the 2nd, main valve housing, the 3rd, O-ring seals, the 4th, the resistance of main valve liquid, the 5th, main valve plug, the 6th, O-ring seals, the 7th, back-up ring, the 8th, O-ring seals, the 9th, back-up ring, the 10th, O-ring seals, the 11st, main spool spring, the 12nd, the resistance of pilot valve liquid, the 13rd, guide's valve body, the 14th, O-ring seals, the 15th, back-up ring, the 16th, guide's valve pocket, the 17th, guide's spool, the 18th, pilot valve end cap, the 19th, pilot valve spring, the 20th, spring pad, the 21st, pad, the 22nd, adjustable lever, the 23rd, nut, the 24th, back-up ring, the 25th, O-ring seals, the 26th, nut, the 27th, back-up ring, the 28th, O-ring seals, the 29th, steel is stifled, and the 30th, O-ring seals, the 31st, O-ring seals, the P mouth is a water intake, and the O mouth is a water outlet, and A is a main valve, B is a pilot valve, and a is a runner, and b is a radial direction through hole, c is a center hole, and f is a center hole, and g is a runner, i is an inclined hole, and m is a radial direction through hole, and n is a radial direction through hole.
Embodiment
Pilot-operated water hydraulic relief valve is combined by main valve A and pilot valve B, in main valve body 1 hole, main valve housing 2 is housed, taper main valve plug 5 with two-step throttle and high-pressure induct structure is positioned at main valve housing 2 holes, and compress by spring 11, when main valve plug 5 is opened, form the variable restrictor valve port of two polyphones between main valve plug 5 and the main valve housing 2, main valve body 1 lower end has water intake P and water outlet O, liquid flow point by water intake P is a two-way, lead up to main valve plug center hole c, main valve liquid resistance 4 is communicated with the main spool spring chamber, another road is communicated with water outlet O by the runner a of formation between main valve plug 5 and the main valve housing 2, has radial direction through hole b in main valve plug 5 center hole c; Set up pilot valve liquid resistance 12 in pilot valve B ingress, make and not only can improve resistance 4 of main valve liquid and pilot valve liquid resistance 12 polyphones the relief valve setting-pressure accuracy, and can avoid elongated hole liquid capacitance-resistance to be prone to blocking problem;
Have six stepped hole in guide's valve body 13 from left to right successively, guide's valve body 13 from left to right first, two, guide's valve pocket 16 is housed in three holes, guide's spool 17 with damping piston is arranged in guide's valve pocket 16 holes, thereby this piston can not only increase the working stability that kinetic damping improves relief valve, can also make guide's spool 17 guiding, can canting after guarantee opening, liquid resistance 12 is housed in the 4th hole, the other end of main valve housing 2 matches with the 6th hole in guide's valve body 13, the other end of main spool spring 11 withstands on the 5th hole end surface in guide's valve body 13, in first hole of guide's valve body 13 pilot valve end cap 18 is housed, pilot valve end cap 18, in adjustable lever 22 is housed, pilot valve spring 19 withstands between guide's spool 17 and the adjustable lever 22, the liquid stream in main spool spring chamber is through the 6th hole of guide's valve body 1, the 5th hole, elder generation's drain resistance 12 enters the 3rd hole, enter pilot valve through the radial direction through hole m on guide's valve pocket 16 then and put center hole f, when guide valve core 17 is opened in the ban, form a variable restrictor valve port between guide's spool 17 and the guide's valve pocket 16, the liquid stream that pilot valve puts in the center hole f flows in guide's valve body first hole through settable orifice and guide's valve pocket radial direction through hole n, liquid stream in the pilot valve spring chamber flows in guide's valve body first hole by the inclined hole i on guide's valve pocket 16, and liquid stream is communicated with main valve water outlet O by the runner g on guide's valve body in guide's valve body first hole; Pilot valve spring 19 is used to set up relief valve pressure, and main spool spring 11 is used for main valve plug 5 is pressed against main valve housing 2, makes primary valve close; When the pressure of main intake valve P reaches the relief valve set pressure, press water enters guide's valve pocket by main valve plug center hole, main valve liquid resistance 4, main spool spring chamber, first drain resistance 12, overcome the spring force of pilot valve spring 19, make guide's spool 17 open, the relief valve overflow, liquid stream forms pressure reduction at the main valve plug two ends simultaneously, and main valve plug 5 is opened, and liquid stream arrives main valve water outlet O through the shaped flow channel that forms between main valve plug 5 and the main valve housing 2.
Seal with O-ring seals 8, back-up ring 9 between main valve plug 5 and the main valve housing 2, respectively with O-ring seals 3, back-up ring and O-ring seals 6, back-up ring 7 sealings, use O-ring seals 10, retaining ring sealing between the 6th hole of main valve housing 2 and guide's valve body 13 between main valve housing 2 and the main valve body 1; Seal with O-ring seals 14, back-up ring 15 between guide's valve pocket 16 and the guide's valve body 13; With O-ring seals 28, back-up ring 27 sealings, seal with O-ring seals 25, back-up ring 24 between adjustable lever 22 and the pilot valve end cap 18 between pilot valve end cap 18 and the guide's valve body 13.
The rated working pressure of this valve is 14MPa (maximum service pressure is 21MPa), and rated flow is 120L/min.
Employing have two-step throttle and high-pressure induct structure the taper main valve plug, have the pilot poppet valve core of damping piston, set up the liquid resistance in the pilot valve ingress, make resistance of main valve liquid and first drain resistance polyphone improve the relief valve setting-pressure accuracy, the non-corrosive material of seal form and special processing combination reliably is the characteristics of this valve.This valve adopts socket head screw to connect main valve body 1 and guide's valve body 13, and main valve plug 5 is contained in the main valve body 1, and main valve housing 2 is contained in main valve body 1 center, and main spool spring 11 is pressed against main valve plug 5 on the main valve housing 2.Main valve body 1 lower end has water intake P and water outlet O, and both are interconnected by main valve plug 5 and the shaped flow channel that main valve housing 2 forms, and intake-outlet adopts board-like connection, and O-ring seals 31 is sealed into water outlet when being used for board-like connection.Add back-up ring 9 sealings by O-ring seals 8 between main valve plug 5 and the main valve housing 2, the form that this employing Sealing directly seals is good in high pressure water ambient condition lower seal performance.Form the variable restrictor valve port of two polyphones between main valve plug 5 and the main valve housing 2, make valve port pressure reduction bear jointly by two restrictions, shaped flow channel between main valve plug 5 and the main valve housing 2 is optimized design, make current smooth more, can reduce the possibility that cavitation erosion takes place greatly, have the high-pressure induct hole at main valve plug 5 centers, utilize the high-pressure induct bundle to influence the main flow bundle, can effectively suppress cavitation erosion, reduce noise, reduce vibration.The pilot-operated water hydraulic relief valve of being developed relies on guide's spring 19 to carry out pressure regulation, turn nut 23 is undertaken spacing by nut 26,22 motions of nut 23 compressing adjustable levers, adjustable lever 22 links to each other with spring pad 20, pad 21 and compresses guide's spring 19, regulating system pressure change.Pilot valve B ingress is provided with first drain resistance 12, liquid stream arrives the pilot valve outlet by first drain resistance 12, guide's spool 17 with the settable orifice that guide's valve pocket 16 forms, seal with O-ring seals 30 in the pilot valve outlet port, the pilot valve outlet communicates with the main valve outlet, belong to the internal control internal drainage type, drain port outside having on pilot valve B is generally used plug 29 shutoff.

Claims (3)

1, a kind of pilot-operated water hydraulic relief valve is characterized in that: comprise that pilot-operated water hydraulic relief valve is combined by main valve (A) and pilot valve (B) arranged coaxial; Wherein:
1) main valve (A): comprise main valve body (1), be contained in the main valve housing (2) in main valve body (1) hole, main valve plug (5) is contained in the main valve housing (2), main valve liquid resistance (4) is housed in main valve plug (5) small through hole, in main valve plug (5) large through-hole main spool spring (11) is housed, when main valve plug (5) is opened, form the variable restrictor valve port of two polyphones between main valve plug (5) and the main valve housing (2), have water intake (P) and water outlet (O) on the main valve body (1), the liquid flow point of water intake (P) is a two-way, lead up to main valve plug center hole (c), main valve liquid resistance (4) is communicated with the main spool spring chamber, another road is communicated with water outlet (O) by the runner (a) of formation between main valve plug (5) and the main valve housing (2), has radial direction through hole (b) in main valve plug (5) center hole (c);
2) pilot valve (B): comprise guide's valve body (13), have six stepped hole in guide's valve body (13) from left to right successively, guide's valve body (13) from left to right first, two, guide's valve pocket (16) is housed in three holes, be contained in the guide's spool (17) in guide's valve pocket (16) hole, pilot valve liquid resistance (12) is housed in the 4th hole, the other end of main valve housing (2) matches with the 6th hole in guide's valve body (13), the other end of main spool spring (11) withstands on the 5th hole end surface in guide's valve body (13), pilot valve end cap (18) is housed in first hole of guide's valve body (13), pilot valve end cap (18), in adjustable lever (22) is housed, pilot valve spring (19) withstands between guide's spool (17) and the adjustable lever (22), the liquid stream in main spool spring chamber is through the 6th hole of guide's valve body (1), the 5th hole, pilot valve liquid resistance (12) enters the 3rd hole, the radial direction through hole (m) that passes through then on guide's valve pocket (16) enters upward center hole (f) of guide's valve pocket (16), when guide valve core (17) is opened in the ban, form a variable restrictor valve port between guide's spool (17) and the guide's valve pocket (16), the liquid stream that guide's valve pocket (16) is gone up in the center hole (f) flows in guide's valve body first hole through settable orifice and guide's valve pocket (16) radial direction through hole (n), liquid stream in the pilot valve spring chamber flows in guide's valve body first hole by the inclined hole (i) on guide's valve pocket (16), and liquid stream is communicated with main valve water outlet (O) by the runner (g) on guide's valve body in guide's valve body (13) first holes;
2, a kind of pilot-operated water hydraulic relief valve according to claim 1, it is characterized in that main valve plug (5) is for having effective inhibition cavitation erosion, reduce noise, the two-step throttle structure that reduces to vibrate, and have at main valve plug (5) center and can influence the high-pressure induct of main flow bundle radial direction through hole (b), set up the pilot valve liquid resistance (12) that can improve the relief valve setting-pressure accuracy in pilot valve (B) ingress, main valve liquid resistance (4) and pilot valve liquid resistance (12) polyphone, guide's spool (17) is for can increase kinetic damping, improve the relief valve working stability, make guide's spool (17) guiding, three grades of cone valve structures of band damping piston that can canting after guaranteeing to open.
3, a kind of pilot-operated water hydraulic relief valve according to claim 1, it is characterized in that: seal with O-ring seals (8) between main valve plug (5) and the main valve housing (2), use the sealing of O-ring seals (3) and O-ring seals (6) between main valve housing (2) and the main valve body (1) respectively, seal with O-ring seals (10) between the 6th hole of main valve housing (2) and guide's valve body (13); Seal with O-ring seals (14) between guide's valve pocket (16) and the guide's valve body (13); With O-ring seals (28) sealing, seal with O-ring seals (25) between adjustable lever (22) and the pilot valve end cap (18) between pilot valve end cap (18) and the guide's valve body (13).
CNB2004100535559A 2004-08-04 2004-08-04 Pilot type pure water overflow valve Expired - Fee Related CN1304761C (en)

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CNB2004100535559A CN1304761C (en) 2004-08-04 2004-08-04 Pilot type pure water overflow valve

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Application Number Priority Date Filing Date Title
CNB2004100535559A CN1304761C (en) 2004-08-04 2004-08-04 Pilot type pure water overflow valve

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CN1587719A true CN1587719A (en) 2005-03-02
CN1304761C CN1304761C (en) 2007-03-14

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100439895C (en) * 2006-01-19 2008-12-03 浙江大学 Oil elastic modulus detector based on volume elastic modulus definition
CN102042432A (en) * 2010-12-10 2011-05-04 北京工业大学 Direct-acting water pressure overflow valve with damping piston
CN105805073A (en) * 2016-05-29 2016-07-27 浙江大学 Cartridge overflow valve main valve with directional damper
CN107489799A (en) * 2017-08-31 2017-12-19 上海立新液压有限公司 A kind of efficient precursor overflow valve
CN111765005A (en) * 2020-06-10 2020-10-13 中国航发北京航科发动机控制系统科技有限公司 Hydraulic stability adjusting device composed of piston damping and variable throttling nozzle
CN112032377A (en) * 2020-08-21 2020-12-04 浙江大学 Quick-response pilot operated safety valve and system overpressure quick protection method
CN114183425A (en) * 2021-11-30 2022-03-15 华中科技大学 Damping element matched with adjustable gap, direct-acting overflow valve and pilot-operated overflow valve

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN85109329B (en) * 1985-12-26 1988-07-20 庄凤龄 Precursory overflow valve
CN86201695U (en) * 1986-03-25 1987-05-06 陕西机械学院 Piston type lead overflow valve
EP0661484B1 (en) * 1993-11-30 1999-08-25 Smc Corporation Double-solenoid type electromagnetic valve
JPH0886380A (en) * 1994-09-13 1996-04-02 Smc Corp Pilot valve
DE29716274U1 (en) * 1997-09-10 1999-01-14 Lorentz, Bernt, 22457 Hamburg Overflow valve
US6554014B2 (en) * 2000-10-13 2003-04-29 Hydraforce, Inc. Proportional pilot operated directional valve
CN2729386Y (en) * 2004-08-04 2005-09-28 浙江大学 Guide water hydraulic relief valve

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100439895C (en) * 2006-01-19 2008-12-03 浙江大学 Oil elastic modulus detector based on volume elastic modulus definition
CN102042432A (en) * 2010-12-10 2011-05-04 北京工业大学 Direct-acting water pressure overflow valve with damping piston
CN102042432B (en) * 2010-12-10 2012-05-23 北京工业大学 Direct-acting water pressure overflow valve with damping piston
CN105805073A (en) * 2016-05-29 2016-07-27 浙江大学 Cartridge overflow valve main valve with directional damper
CN105805073B (en) * 2016-05-29 2017-08-25 浙江大学 A kind of plug-in overflow valve main valve that there is orientation to damp
CN107489799A (en) * 2017-08-31 2017-12-19 上海立新液压有限公司 A kind of efficient precursor overflow valve
CN107489799B (en) * 2017-08-31 2023-11-03 上海立新液压有限公司 Efficient guide overflow valve
CN111765005A (en) * 2020-06-10 2020-10-13 中国航发北京航科发动机控制系统科技有限公司 Hydraulic stability adjusting device composed of piston damping and variable throttling nozzle
CN112032377A (en) * 2020-08-21 2020-12-04 浙江大学 Quick-response pilot operated safety valve and system overpressure quick protection method
CN114183425A (en) * 2021-11-30 2022-03-15 华中科技大学 Damping element matched with adjustable gap, direct-acting overflow valve and pilot-operated overflow valve
CN114183425B (en) * 2021-11-30 2023-02-14 华中科技大学 Damping element matched with adjustable gap, direct-acting overflow valve and pilot-operated overflow valve

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