CN111997964A - High-frequency-response high-precision direction displacement hydraulic system and load control method thereof - Google Patents
High-frequency-response high-precision direction displacement hydraulic system and load control method thereof Download PDFInfo
- Publication number
- CN111997964A CN111997964A CN202010685989.XA CN202010685989A CN111997964A CN 111997964 A CN111997964 A CN 111997964A CN 202010685989 A CN202010685989 A CN 202010685989A CN 111997964 A CN111997964 A CN 111997964A
- Authority
- CN
- China
- Prior art keywords
- valve
- speed switch
- port
- load
- way proportional
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
- F15B21/02—Servomotor systems with programme control derived from a store or timing device; Control devices therefor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B19/00—Testing; Calibrating; Fault detection or monitoring; Simulation or modelling of fluid-pressure systems or apparatus not otherwise provided for
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Fluid-Pressure Circuits (AREA)
- Multiple-Way Valves (AREA)
Abstract
The invention discloses a high-frequency-response high-precision direction displacement hydraulic system and a load control method thereof. The system comprises a hydraulic unit, a controller and an LVDT displacement sensor; the hydraulic unit consists of a three-position four-way proportional valve and two high-speed switch valves; the hydraulic unit is provided with four oil ports of a PTAB (proportional-integral-differential), wherein a T port is connected with an oil outlet of the first high-speed switch valve, and an oil inlet of the first high-speed switch valve is connected with a D port of the three-position four-way proportional valve; the port P is connected with an oil inlet of a second high-speed switch valve, and an oil outlet of the second high-speed switch valve is connected with a port C of the three-position four-way proportional valve; the hydraulic unit provided by the invention is formed by connecting a three-position four-way proportional valve and two high-speed switch valves in series, and replaces the original full-bridge loop structure of four high-speed switch valves, so that the motion state of a load can be efficiently and accurately controlled, the effect of large gain of the proportional valve can be brought, and accurate control and feedback adjustment can be carried out by utilizing the characteristic of quick response of the switch valves.
Description
Technical Field
The invention relates to the field of hydraulic valve control, in particular to a high-frequency-response high-precision directional displacement hydraulic system and a load control method thereof.
Background
In recent years, the electro-hydraulic control technology is rapidly developed and widely applied to mechanical industries such as civil, industrial, military and aerospace industries. The traditional electro-hydraulic proportional valve adopts a valve core for control, the displacement of the valve core is controlled according to a voltage value input by a user, the flow of a corresponding value is output, and the output control of flow analog quantity is realized.
Along with the frequency increase of the high-speed switch valve, more and more hydraulic systems adopt the high-speed switch valve to carry out closed-loop control, and the high-speed switch valve can replace the position control of the proportional valve to the load in some fields due to the advantages of simple structure, low price, high reliability and the like. However, the high-frequency opening and closing of the high-speed switching valve can bring jitter to the actuator, and influence the dynamic characteristics of the actuator.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a high-frequency-response high-precision direction displacement hydraulic system and a load control method thereof. The hydraulic unit provided by the invention is formed by connecting a three-position four-way proportional valve and two high-speed switch valves in series, and replaces the original full-bridge loop structure of four high-speed switch valves, so that the motion state of a load can be efficiently and accurately controlled, the effect of large gain of the proportional valve can be brought, and accurate control and feedback adjustment can be carried out by utilizing the characteristic of quick response of the switch valves.
The technical scheme of the invention is as follows:
the invention discloses a high-frequency-response high-precision direction displacement hydraulic system which comprises a hydraulic unit, a controller and an LVDT displacement sensor, wherein the controller is connected with the hydraulic unit; the hydraulic unit consists of a three-position four-way proportional valve and two high-speed switch valves; the hydraulic unit is provided with P, T, A, B four oil ports, wherein a T port is connected with an oil outlet of the first high-speed switch valve, and an oil inlet of the first high-speed switch valve is connected with a D port of the three-position four-way proportional valve; the port P is connected with an oil inlet of a second high-speed switch valve, and an oil outlet of the second high-speed switch valve is connected with a port C of the three-position four-way proportional valve; the port A and the port B of the three-position four-way proportional valve are respectively used as the port A and the port B of the hydraulic unit;
the LVDT displacement sensor is connected with the controller and used for detecting the load state; the controller respectively controls the three-position four-way proportional valve and the two high-speed switch valves, wherein the controller controls the two high-speed switch valves by adopting PWM digital signals.
Preferably, the two high-speed switching valves are integrated in the three-position four-way proportional valve. The three-position four-way proportional valve is characterized in that two high-speed switch valve mounting holes are formed in a valve block of the three-position four-way proportional valve, the two high-speed switch valves are respectively mounted in the two high-speed switch valve mounting holes, and P, T, A, B four oil ports are formed in the valve block and are respectively used as P, T, A, B oil ports of the hydraulic unit. The T port on the valve block is connected with the oil outlet of the first high-speed switch valve through an oil path arranged in the valve block, and the oil inlet of the first high-speed switch valve is connected with the D port of the three-position four-way proportional valve through an oil path arranged in the valve block; the port P is connected with an oil inlet of a second high-speed switch valve through an oil way arranged in the valve block, and an oil outlet of the second high-speed switch valve is connected with a port C of the three-position four-way proportional valve through an oil way arranged in the valve block; the port A and the port B of the three-position four-way proportional valve are connected with the port A and the port B of the valve block through oil passages formed in the valve block.
The invention also discloses a load displacement control method based on the high-frequency-response high-precision direction displacement hydraulic system, which comprises the following steps:
in the initial stage of load movement, the two high-speed switch valves are all opened, and the flow is controlled through the three-position four-way proportional valve, so that the load can rapidly move to approach a designated position;
when the load is close to the designated position, the valve ports of the three-position four-way proportional valve are reduced, and the overall flow of the hydraulic unit is reduced; the high-speed switch valve is controlled to be opened and closed through the PWM signal, so that higher-precision control is realized, and the load is enabled to reach a specified position;
if the load position exceeds the designated position, the flow direction is adjusted through the three-position four-way proportional valve, and the high-speed switch valve is controlled to be opened and closed through the PWM signal, so that the load reaches the designated position.
The invention further discloses a control method of the load motion parameters of the high-frequency response high-precision direction displacement hydraulic system, which comprises the following steps:
the on-position LVDT displacement sensor detects the motion parameters of the load, in the initial stage, the two high-speed switch valves are all opened, and the three-position four-way proportional valve is used for controlling the motion parameters of the load, so that the motion parameters of the load are close to a preset target value;
when the load motion parameters are close to the preset target values, the valve ports of the three-position four-way proportional valve are reduced, and the high-speed switch valve is controlled to be opened and closed through the PWM signals, so that the high-precision control of the load motion parameters is realized, and the load motion parameters are enabled to reach and be maintained at the target values.
Compared with the prior art, the hydraulic unit provided by the invention is formed by connecting a three-position four-way proportional valve and two high-speed switch valves in series, and replaces the original full-bridge loop structure of four high-speed switch valves to realize the efficient and accurate control of the motion state of a load, so that the effect of large gain of the proportional valve can be brought, the accurate control and feedback adjustment can be carried out by utilizing the characteristic of fast response of the switch valves, the opening and closing characteristics of all the high-speed switch valves in the unit are consistent, the dynamic response is good, and the conventional switch valves only have two states of 'on' and 'off', so the flow resolution ratio is lower, and the occasions with higher requirements on the flow resolution ratio and the precision cannot be met. However, in the present invention, the PWM digital signal is used to control the high-speed switching valve, and although the high-speed switching valve is always operated in a fully open or fully closed state, the high-precision flow output can be realized by changing the duty ratio of the PWM signal through calculation according to the demand.
The feedback form of the load adopts displacement-electric feedback, the displacement of the load is collected through the LVDT and fed back to the controller, and signals are sent to the PWM output through operation.
Drawings
FIG. 1 is a schematic structural and schematic view of the present invention;
FIG. 2 is a schematic exterior view of a hydraulic unit according to the present invention;
FIG. 3 is a side view of the hydraulic unit of the present invention;
FIG. 4 is a cross-sectional view A-A of FIG. 3;
FIG. 5 is a schematic top view of the hydraulic unit of the present invention;
FIG. 6 is a cross-sectional view B-B of FIG. 5;
FIG. 7 is a schematic diagram of the oil circuit structure of the present invention;
fig. 8 is a schematic structural view of the high-speed switching valve of the present invention.
Detailed Description
The invention will be further illustrated and described with reference to specific embodiments. The technical features of the embodiments of the present invention can be combined correspondingly without mutual conflict.
As shown in fig. 1, the high-frequency-response high-precision direction displacement hydraulic system of the invention comprises a hydraulic unit, a controller and an LVDT displacement sensor; the hydraulic unit consists of a three-position four-way proportional valve and two high-speed switch valves; the hydraulic unit is provided with P, T, A, B four oil ports, wherein a T port is connected with an oil outlet of the first high-speed switch valve, and an oil inlet of the first high-speed switch valve is connected with a D port of the three-position four-way proportional valve; the port P is connected with an oil inlet of a second high-speed switch valve, and an oil outlet of the second high-speed switch valve is connected with a port C of the three-position four-way proportional valve; the port A and the port B of the three-position four-way proportional valve are respectively used as the port A and the port B of the hydraulic unit;
the LVDT displacement sensor is connected with the controller and used for detecting the load state; the controller respectively controls the three-position four-way proportional valve and the two high-speed switch valves, wherein the controller controls the two high-speed switch valves by adopting PWM digital signals.
The present invention further provides an implementation of a hydraulic unit, as shown in fig. 2-8. In this implementation, the two high speed switching valves 1-A and 1-B are integrated within a three-position, four-way proportional valve 6. The integration refers to a valve component integrating a high-speed switch valve and a three-position four-way proportional valve.
The three-position four-way proportional valve is characterized in that a valve block of the three-position four-way proportional valve is provided with two high-speed switch valve mounting holes, two high-speed switch valves 1-A and 1-B are respectively mounted in the two high-speed switch valve mounting holes, and the valve block is provided with a P port 5, a T port 4, an A port 2 and a B port 3 which are respectively used as P, T, A, B oil ports of a hydraulic unit.
The hydraulic unit is obtained by adding two high-speed switch valves on a valve block of a traditional three-position four-way proportional valve, wherein the two high-speed switch valves are arranged on the valve block of the original three-position four-way proportional valve, a T port on the valve block is connected with an oil outlet of a first high-speed switch valve 1-A through an oil path formed in the valve block, and an oil inlet of the first high-speed switch valve is connected with a D port of the three-position four-way proportional valve through an oil path formed in the valve block; the port P is connected with oil inlets of the second high-speed switch valves 1-B through oil paths formed in the valve blocks, and oil outlets of the second high-speed switch valves are connected with a port C of the three-position four-way proportional valve through oil paths formed in the valve blocks; the port A and the port B of the three-position four-way proportional valve are connected with the port A and the port B of the valve block through oil passages formed in the valve block.
The invention can control the flow direction of the A/B port through the three-position four-way proportional valve and control the flow of the A/B port by using the high-speed switch valve 1-B/1-A.
The three-position four-way proportional valve is in the prior art, as shown in fig. 4, the main components of the three-position four-way proportional valve 6 are a valve core 7 and a left electromagnet assembly and a right electromagnet assembly, each electromagnet assembly mainly comprises an electromagnet magnetic conduction shell 6-4, an electromagnet 6-2, a coil 6-1 and a magnetism isolating ring 6-3, the coil 6-1 is used for driving the electromagnet 6-2, and the magnetism isolating ring 6-plays a role in magnetic isolation. Except that the three-position four-way proportional valve is provided with two high-speed switch valves, a valve core, an oil way and an electromagnet assembly of the three-position four-way proportional valve are the same as those of the three-position four-way proportional valve in the prior art; the left electromagnet assembly and the right electromagnet assembly can push the valve core 7 to move, so that the proportional valve is closed or in different working modes.
The D port of the three-position four-way proportional valve and the C port of the three-position four-way proportional valve are understood to be positioned in the valve block, wherein if the first high-speed switch valve and the second high-speed switch valve are completely opened and are controlled by PWM signals, the D port of the three-position four-way proportional valve and the C port of the three-position four-way proportional valve are respectively a T port and a P port of the hydraulic unit.
The high-speed switch valve of the embodiment can be a high-speed switch valve in the prior art, as shown in fig. 6 and 8, the high-speed switch valve is a schematic structural diagram of the two-position two-way high-speed switch valve of the invention, the high-speed switch valve is arranged on a valve block of a proportional valve and is sealed by an end cover 1-1, and main components of the high-speed switch valve comprise a push rod 1-3 and a small coil 1-2 for driving the push rod; the beads 1-4 are arranged in the guard ring to play a role in determining the closing of the switch valve, and the push rod 1-3 can push the beads 1-4 to close the switch valve. The oil outlet and the oil inlet of the two-position two-way high-speed switch valve are connected with the corresponding oil port of the proportional valve or the external oil port of the valve block through an oil way branch.
Fig. 7 is a schematic diagram of the oil path structure of the present invention, and it can be seen from the diagram that the T port is connected to the oil outlet of the first high-speed switch valve, and the P port is connected to the oil inlet of the second high-speed switch valve.
The two high-speed on-off valves described in this embodiment are normally open valves. The two high-speed switch valves are completely the same; the side wall of the high-speed switch valve is an oil outlet, and the bottom of the high-speed switch valve is an oil inlet (an oil inlet)
The controller can adopt DSP, ARM and other controllers. The LVDT displacement sensor is used for collecting the load state and is connected with the input end of the controller; the controller is used for respectively controlling the 1-A high-speed switch valve and the 1-B high-speed switch valve through PWM signals and controlling the three-position four-way proportional valve. The high-speed switch valve has high response characteristic. The invention can be realized in the aspect of controlling aiming at different load state requirements:
and controlling the displacement of the load, namely requiring the load to accurately reach the specified displacement and stop. The three-position four-way proportional valve has the functions of flow reversing and proportional flow control. However, due to the structure of the three-position four-way proportional valve, the three-position four-way proportional valve has poor dynamic response characteristics, high-precision flow control cannot be realized, and the accuracy of load displacement cannot be realized by only relying on the three-position four-way proportional valve; the high-speed switch valve has better dynamic response characteristics, and although the flow reversing can not be realized by a single high-speed switch valve, the flow can be accurately controlled. Therefore, when the load displacement is accurately controlled, the high-speed switch valves are all opened in the initial stage, the three-position four-way proportional valve is used for controlling the large flow, and the load is quickly displaced to approach the designated position. When the load is close to the later stage of the designated position, the valve ports of the three-position four-way proportional valve are reduced, the whole flow is reduced, the high-speed switch valve is controlled through the PWM signal, the control with higher precision is realized, and the load can accurately reach the designated position. If the load position exceeds the designated position in the actual control due to the hysteresis of the hydraulic valve, the flow direction can be adjusted by the three-position four-way proportional valve, and the position is adjusted by the high-speed switch valve.
Aiming at load speed control, namely realizing the stable movement of the load at a certain speed. When the speed is regulated and controlled by only depending on the high-speed switch valve, the speed fluctuation is large due to large duty ratio change, and the speed is not suitable for speed stability. The speed cannot be accurately controlled due to the fixed opening of the valve port of the proportional valve which is only dependent on the proportional valve. Therefore, by the displacement control, the load speed is made close to the specified speed by the rough speed control by the proportional valve. The high speed switching valve is controlled by a PWM signal with a higher duty cycle, because the PWM signal has a higher duty cycle, the speed is more stable.
Similarly, the acceleration of the load can be controlled in a similar manner.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (9)
1. A high-frequency-response high-precision direction displacement hydraulic system is characterized by comprising a hydraulic unit, a controller and an LVDT displacement sensor; the hydraulic unit consists of a three-position four-way proportional valve and two high-speed switch valves; the hydraulic unit is provided with P, T, A, B four oil ports, wherein a T port is connected with an oil outlet of the first high-speed switch valve, and an oil inlet of the first high-speed switch valve is connected with a D port of the three-position four-way proportional valve; the port P is connected with an oil inlet of a second high-speed switch valve, and an oil outlet of the second high-speed switch valve is connected with a port C of the three-position four-way proportional valve; the port A and the port B of the three-position four-way proportional valve are respectively used as the port A and the port B of the hydraulic unit;
the LVDT displacement sensor is connected with the controller and used for detecting the load state; the controller respectively controls the three-position four-way proportional valve and the two high-speed switch valves, wherein the controller controls the two high-speed switch valves by adopting PWM digital signals.
2. The high frequency response high precision direction displacement hydraulic system of claim 1, wherein the two high speed switching valves are integrated into a three-position four-way proportional valve.
3. The high-frequency-response high-precision direction displacement hydraulic system as claimed in claim 2, wherein two high-speed switch valve mounting holes are formed in the valve block of the three-position four-way proportional valve, the two high-speed switch valves are respectively mounted in the two high-speed switch valve mounting holes, and P, T, A, B four oil ports are formed in the valve block and respectively serve as P, T, A, B oil ports of the hydraulic unit.
4. The high-frequency response high-precision direction displacement hydraulic system as claimed in claim 3, wherein a T port on the valve block is connected with an oil outlet of the first high-speed switch valve through an oil path formed in the valve block, and an oil inlet of the first high-speed switch valve is connected with a D port of the three-position four-way proportional valve through an oil path formed in the valve block; the port P is connected with an oil inlet of a second high-speed switch valve through an oil way arranged in the valve block, and an oil outlet of the second high-speed switch valve is connected with a port C of the three-position four-way proportional valve through an oil way arranged in the valve block; the port A and the port B of the three-position four-way proportional valve are connected with the port A and the port B of the valve block through oil passages formed in the valve block.
5. The high frequency response high precision direction displacement hydraulic system of claim 1, wherein the two high speed switch valves are normally open valves.
6. A high frequency response high precision direction displacement hydraulic system as claimed in claim 1, wherein said two high speed switch valves are identical.
7. A load displacement control method of a high frequency response high precision direction displacement hydraulic system according to claim 1, characterized in that:
in the initial stage of load movement, the two high-speed switch valves are all opened, and the flow is controlled through the three-position four-way proportional valve, so that the load can rapidly move to approach a designated position;
when the load is close to the designated position, the valve ports of the three-position four-way proportional valve are reduced, and the overall flow of the hydraulic unit is reduced; the high-speed switch valve is controlled to be opened and closed through the PWM signal, so that higher-precision control is realized, and the load is enabled to reach a specified position;
if the load position exceeds the designated position, the flow direction is adjusted through the three-position four-way proportional valve, and the high-speed switch valve is controlled to be opened and closed through the PWM signal, so that the load reaches the designated position.
8. A method for controlling the load motion parameters of a high frequency response high precision direction displacement hydraulic system based on claim 1, characterized in that:
the on-position LVDT displacement sensor detects the motion parameters of the load, in the initial stage, the two high-speed switch valves are all opened, and the three-position four-way proportional valve is used for controlling the motion parameters of the load, so that the motion parameters of the load are close to a preset target value;
when the load motion parameters are close to the preset target values, the valve ports of the three-position four-way proportional valve are reduced, and the high-speed switch valve is controlled to be opened and closed through the PWM signals, so that the high-precision control of the load motion parameters is realized, and the load motion parameters are enabled to reach and be maintained at the target values.
9. The method for controlling the load motion parameters of the high frequency response high precision direction displacement hydraulic system as claimed in claim 8, wherein: the load motion parameter is load motion speed or load motion acceleration.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010685989.XA CN111997964B (en) | 2020-07-16 | 2020-07-16 | High-frequency-response high-precision direction displacement hydraulic system and load control method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010685989.XA CN111997964B (en) | 2020-07-16 | 2020-07-16 | High-frequency-response high-precision direction displacement hydraulic system and load control method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111997964A true CN111997964A (en) | 2020-11-27 |
| CN111997964B CN111997964B (en) | 2022-04-22 |
Family
ID=73467419
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010685989.XA Active CN111997964B (en) | 2020-07-16 | 2020-07-16 | High-frequency-response high-precision direction displacement hydraulic system and load control method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111997964B (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003148419A (en) * | 2001-11-08 | 2003-05-21 | Hitachi Constr Mach Co Ltd | Driving device of running motor |
| CN101603876A (en) * | 2009-06-30 | 2009-12-16 | 浙江工业大学 | Vibration waveform controlling system of electro-hydraulic exciter |
| CN106382271A (en) * | 2016-10-18 | 2017-02-08 | 浙江大学 | Dual-valve-element programmable control hydraulic valve piloted by high-speed switching valves and control method of dual-valve-element programmable control hydraulic valve |
| CN109236775A (en) * | 2018-09-29 | 2019-01-18 | 南京航空航天大学 | A kind of big flow ratio valve module and its control method based on high-speed switch valve guide adjusting |
| CN109654079A (en) * | 2017-10-12 | 2019-04-19 | 华东交通大学 | The outlet throttling load port separate control valves that full switch valve group is closed |
-
2020
- 2020-07-16 CN CN202010685989.XA patent/CN111997964B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003148419A (en) * | 2001-11-08 | 2003-05-21 | Hitachi Constr Mach Co Ltd | Driving device of running motor |
| CN101603876A (en) * | 2009-06-30 | 2009-12-16 | 浙江工业大学 | Vibration waveform controlling system of electro-hydraulic exciter |
| CN106382271A (en) * | 2016-10-18 | 2017-02-08 | 浙江大学 | Dual-valve-element programmable control hydraulic valve piloted by high-speed switching valves and control method of dual-valve-element programmable control hydraulic valve |
| CN109654079A (en) * | 2017-10-12 | 2019-04-19 | 华东交通大学 | The outlet throttling load port separate control valves that full switch valve group is closed |
| CN109236775A (en) * | 2018-09-29 | 2019-01-18 | 南京航空航天大学 | A kind of big flow ratio valve module and its control method based on high-speed switch valve guide adjusting |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111997964B (en) | 2022-04-22 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3260273A (en) | Motor valve having differential pressure feedback | |
| RU2010124833A (en) | ELECTROHYDRAULIC PROPORTIONAL VALVE CONTROL SYSTEM REGULATING THE FLOW SPEED AND METHOD FOR ITS IMPLEMENTATION | |
| CN112196852A (en) | Digital fluid pilot-driven double-spool programmable control hydraulic valve and control method thereof | |
| CN101963166A (en) | Dual-mode electric digital valve | |
| US11092173B2 (en) | Flow control for an actuator | |
| CN105545852A (en) | High-speed switch pilot proportioning valve | |
| CN1230629C (en) | High-speed numerical control proportion valve | |
| CN111997964B (en) | High-frequency-response high-precision direction displacement hydraulic system and load control method thereof | |
| US8313082B2 (en) | Proportional position feedback hydraulic servo system | |
| CN2775363Y (en) | Dynamic pressure feedback electrohydraulic servo valve | |
| CN2886156Y (en) | Flow control type hydraulic main distributing valve capable of automatically returning to center | |
| CN2846835Y (en) | Pressure flow electrohydraulic servo valve | |
| CN114087149B (en) | Variable control loop of plunger pump with double-cavity independent control and multi-mode switching control method | |
| CN212429384U (en) | Hydraulic valve unit for composite control of digital fluid and continuous fluid | |
| CN116044841A (en) | Pressure flow high-precision control method based on electromagnetic switch valve | |
| Linnett et al. | An accurate low-friction pneumatic position control system | |
| CN105465079A (en) | Brake control oil way | |
| Dong et al. | Compound control strategy for independent metering directional valve of engineering machinery by simulation | |
| CN102434516A (en) | Electromagnet differential motion driving method for double-electromagnet proportional directional-flow valve | |
| JPH10299711A (en) | Flow rate direction switching valve | |
| CN2851675Y (en) | Electro-hydraulic servo valve for load pressure feedback | |
| CN111927843B (en) | Digital fluid and continuous fluid compound control hydraulic valve unit and control method thereof | |
| CN1815044A (en) | Dynamical pressure feedback electro-hydraulic servo valve | |
| CN111927842B (en) | Digital fluid pilot driven programmable control assembled hydraulic multi-way valve | |
| CN2690928Y (en) | Hydraulic servo synchronous controller |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |