A double-nozzle flapper-type electric feedback servo valve driven by a linear motor

Abstract

The application discloses a double-nozzle baffle type electric feedback servo valve driven by a linear motor, which comprises a driving stage, a pre-stage and a power stage, wherein the driving stage comprises a linear motor, a connecting rod, an electric connector, a motor base and an end cover; the pre-stage comprises a baffle, a knuckle bearing and a nozzle; the power stage comprises a valve core, a magnetic head connecting rod, an electric displacement sensor LVDT, a shell, a right end cover, a left end cover and a cover; linear motion of the linear motor and the connecting rod is converted into deflection of the baffle; the baffle deflection changes the gap between the nozzle and the left and right sides of the baffle, realizes nozzle-baffle variable throttling, generates a pressure difference acting on the left and right end faces of the valve core, drives the valve core of the power stage to move, and finally uses the electric displacement sensor to detect the valve core position. The application adopts the linear motor to replace the torque motor to drive the double-nozzle baffle, adopts the electric feedback to replace the mechanical feedback, omits the part with extremely high machining precision requirement, avoids spring tube breakage, and reduces the machining and motor assembly difficulty.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electro-hydraulic servo control, in particular to a double-nozzle baffle type electric feedback servo valve driven by a linear motor. BACKGROUND

[0002] At present, the double-nozzle baffle type electro-hydraulic servo valves in the industry are all driven by torque motors, and the working principle is that the armature in the torque motor drives the baffle to deflect under the driving of the electromagnetic torque, the baffle deflection causes the left and right nozzles to produce different degrees of throttling and form a pressure difference, thereby driving the spool to move and controlling the opening and closing of the valve port, the spool movement drives the feedback lever to deflect, and the feedback lever converts the spool displacement into a feedback torque, which is fed back to the armature assembly of the torque motor, and balances with the electromagnetic force, wherein the armature assembly adopts a spring tube support structure, the spring tube support allows the armature assembly to freely return to the center when there is no electromagnetic force, realizing the isolation of the nozzle overflow cavity oil and the outside and the non-contact friction movement of the baffle, and the resolution accuracy is high.

[0003] However, in the double-nozzle baffle structure, the wall thickness of the spring tube is only 60μm, the roundness requirement and coaxiality requirement of the inner and outer circles of the thin wall are both less than 2μm, the machining difficulty is great, and the spring tube is easily broken during machining or use, resulting in performance failure of the servo valve, in addition, the existing servo valve structure often adopts a mechanical feedback lever, which has very strict requirements for the stiffness of the feedback lever, and during the grinding process of the feedback lever, the taper and the matching precision of the ball head and the spool groove need to be accurately controlled, the machining precision requirement is extremely high, and the scrap rate of the parts is also high. SUMMARY

[0004] The technical problem solved by the present application is to provide a double-nozzle baffle type electric feedback servo valve driven by a linear motor, to solve the problems of high machining precision and great difficulty of the spring tube and feedback lever of the existing servo valve.

[0005] To solve the above problems, the present application discloses a double-nozzle baffle type electric feedback servo valve driven by a linear motor, the servo valve comprising a driving stage, a pre-stage, and a power stage;

[0006] The driving stage comprises a linear motor, a connecting rod, an electrical connector, a motor seat, and an end cover, the pre-stage comprises a baffle, a knuckle bearing, a nozzle, and a first stage seat, and the power stage comprises a valve, a magnetic head connecting rod, an electrical displacement sensor LVDT, a housing, a right end cover, a left end cover, and a cover.

[0007] The linear motor is connected with a connecting rod, the connecting rod is connected with an upper end of a baffle, the baffle is deflected around a joint bearing to form a lever with the joint bearing as a fulcrum; the linear motion of the linear motor and the connecting rod is converted into deflection of the baffle, and torque amplification is realized through the lever principle; the nozzle is two, symmetrically distributed on both sides of the baffle, and is press-fitted at the lower end of the joint bearing; the valve core is fixed below the nozzle; the deflection of the baffle changes the gap between the nozzle and the left and right sides of the baffle, realizes variable throttling of the nozzle and the baffle, and the generated pressure difference acts on the left and right end faces of the valve core to drive the valve core to move; the electric displacement sensor LVDT includes an LVDT sleeve and an LVDT body, the LVDT sleeve is installed on the surface of the left end cover, and the LVDT body is installed outside the LVDT sleeve; the magnetic head connecting rod is located on one side of the valve core, and the magnetic head of the magnetic head connecting rod is located at one end of the connecting rod close to the LVDT body; the electric displacement sensor LVDT is used to detect the position of the valve core.

[0008] Preferably, the linear motor, the connecting rod, and the electric connector are installed on a motor seat, the baffle, the joint bearing, and the nozzle are installed on a primary seat, and the valve core, the magnetic head connecting rod, and the electric displacement sensor LVDT are installed on a shell; the motor seat, the primary seat, and the shell are connected in sequence for fixing of the structure and the oil circuit.

[0009] Preferably, the electric connector is used to connect a circuit, and the extension and contraction displacement of the linear motor is linearly proportional to the control current.

[0010] Preferably, the upper end of the baffle is fixed to the connecting rod through internal and external tooth screws and a locking nut.

[0011] Preferably, the front stage adopts a hydraulic bridge circuit, the throttling elements of which include a pair of throttling devices and a pair of nozzles; the throttling devices are symmetrically located at both ends of a filter element, high-pressure oil enters the throttling devices after being filtered by the filter element, and then flows through the nozzles.

[0012] Preferably, the nozzle outlet is an overflow cavity, a damping block with a small hole is arranged inside the overflow cavity for adjusting the reference pressure of the hydraulic bridge circuit; the small hole of the damping block has different diameters, and the diameter can be replaced according to the working condition requirements.

[0013] Preferably, sealing rings and plugs are arranged inside the servo valve for realizing isolation or sealing of the oil circuit; the LVDT sleeve of the electric displacement sensor LVDT is used to realize oil isolation of the LVDT body and the magnetic head.

[0014] Preferably, the end cover, the right end cover, the left end cover, and the cover are the servo valve shell, which is used to fix the internal parts of the servo valve or protect the servo valve.

[0015] Preferably, the electric displacement sensor LVDT is connected with the LVDT modem outside the servo valve and the servo amplifier in turn, the electric displacement sensor LVDT modem completes the signal calculation of the LVDT, and feeds back to the servo amplifier, and the servo amplifier outputs bidirectional current to the servo valve, so that the closed-loop control of the servo valve is realized through position feedback.

[0016] Preferably, the linear motor replaces the torque motor of the traditional servo valve, and the electric displacement sensor LVDT replaces the feedback rod of the traditional servo valve, so that the spring tube and the feedback rod structure are omitted.

[0017] The present application has the following beneficial effects:

[0018] (1) The linear motor is used to replace the torque motor to drive the double-nozzle baffle, the machining precision requirement of the part of the spring tube is extremely high, the machining requirement of the part is greatly reduced, and the risk of spring tube rupture is avoided;

[0019] (2) The lever structure with joint bearing is used to convert the linear motion of the linear motor into rotary motion, and the output torque is amplified, so that the load capacity of the motor is improved;

[0020] (3) The electric feedback is used to replace the mechanical feedback, the feedback rod part is omitted, and the assembly difficulty of the motor and the part machining difficulty are greatly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a kind of double-nozzle baffle type electric feedback servo valve structure and working principle schematic diagram driven by linear motor provided by the present application.

[0022] Figure 2 It is a kind of double-nozzle baffle type electric feedback servo valve pre-stage structure schematic diagram driven by linear motor provided by the present application.

[0023] The figure mark is: 1, linear motor;2, electric connector;3, sealing ring;4, connecting rod;5, inner and outer tooth screw;6, locking nut;7, motor seat;8, sealing ring;9, end cover;10, baffle;11, sealing ring;12, joint bearing;13, primary seat;14, nozzle;15, plug;16, sealing ring;17, plug;18, sealing ring;19, right end cover;20, sealing ring;21, shell;22, valve core;23, valve sleeve;24, sealing ring;25, magnetic head connecting rod;26, left end cover;27, electric displacement sensor LVDT sleeve;28, electric displacement sensor LVDT body;29, nut;30, cover;31, restrictor;32, filter element;33, sealing ring;34, plug;36, plug;37, damping block;38, overflow cavity. DETAILED DESCRIPTION

[0024] The embodiments of the present application will be described in further detail below with reference to the drawings, obviously, the described embodiments are only part of the embodiments of the present application, but not all the embodiments.

[0025] As Figure 1 The application discloses a double-nozzle baffle type electric feedback servo valve driven by a linear motor, and a structure and working principle schematic diagram of the double-nozzle baffle type electric feedback servo valve driven by the linear motor are shown, the servo valve comprises a driving stage, a pre-stage, a power stage, wherein: the driving stage comprises a linear motor 1, a connecting rod 4, an electric connector 2, a motor base 7 and an end cover 9; the pre-stage comprises a baffle 10, a knuckle bearing 12, a nozzle 14 and a primary seat 13; the power stage comprises a valve core 22, a magnetic head connecting rod 25, an electric displacement sensor LVDT, a shell 21, a right end cover 19, a left end cover 26 and a cover 30; the linear motor 1 is connected with the connecting rod 4, the connecting rod 4 is connected with the upper end of the baffle 10, the baffle 10 is deflected around the knuckle bearing 12, and a lever with the knuckle bearing 12 as a fulcrum is formed; the linear motion of the linear motor 1 and the connecting rod 4 is converted into the deflection of the baffle 10, and the output torque amplification is realized through the lever principle; the nozzle 14 is provided with two nozzles, which are symmetrically distributed on the left and right sides of the baffle 10 and are press-fitted at the lower end of the knuckle bearing 12, and the valve core 22 is fixed below the nozzle 14; the deflection of the baffle 10 changes the gap between the nozzle 14 and the left and right sides of the baffle 10, realizes variable throttling of the nozzle and the baffle, generates a pressure difference acting on the left and right end faces of the valve core 22, and drives the valve core 22 to move; the electric displacement sensor LVDT comprises an LVDT sleeve 27 and an LVDT body 28, the LVDT sleeve 27 is installed on the surface of the left end cover 26, and the LVDT body 28 is installed outside the LVDT sleeve 27; the magnetic head connecting rod 25 is located on one side of the valve core 22, and the magnetic head of the magnetic head connecting rod 25 is located at one end of the connecting rod close to the LVDT body; the electric displacement sensor LVDT is used for detecting the position of the valve core 22.

[0026] The linear motor 1, the connecting rod 4 and the electric connector 2 are installed on the motor base 7, the baffle 10, the knuckle bearing 12 and the nozzle 14 are installed on the primary seat 13, and the valve core 22, the magnetic head connecting rod 25 and the electric displacement sensor LVDT are installed on the shell 21; the motor base 7, the primary seat 13 and the shell 21 are sequentially connected and used for fixing the structure and the oil circuit.

[0027] The electric connector 2 is used for connecting a circuit, and the extension and contraction displacement of the linear motor 1 is approximately linear in proportion to the control current.

[0028] The upper end of the baffle 10 is fixed to the connecting rod 4 by the internal and external screw 5 and the locking nut 6, in order to ensure the adjustment of the nozzle baffle zero position, the baffle 10 can rotate around the internal and external screw 5 and the locking nut 6, but the freedom of movement along the connecting rod 4 direction is limited, in order to avoid the over positioning caused by the installation error, the connecting rod 4 is a flexible rod with elasticity.

[0029] As Figure 2 The schematic diagram of the double nozzle baffle type electric feedback servo valve pre-stage structure driven by the linear motor is shown, the pre-stage adopts the hydraulic bridge circuit, the throttling element includes a pair of throttlers 31 and a pair of nozzles 14; the throttlers 31 are symmetrically located at both ends of the filter core 32, the high pressure oil enters the throttler 31 after being filtered by the filter core 32, and then flows through the nozzle 14; the outlet of the nozzle 14 is the overflow cavity 38, the inside of the overflow cavity 38 is provided with the damping block 37 with a small hole, which is used for adjusting the reference pressure of the hydraulic bridge circuit; the small hole diameter of the damping block 37 is different, and the hole diameter is replaced according to the working condition requirement.

[0030] The servo valve is internally provided with the sealing ring and the plug, which is used for realizing the isolation or sealing of the oil circuit; the LVDT sleeve 27 is used for realizing the oil isolation of the potential displacement sensor LVDT body 28 and the magnetic head connecting rod 25 magnetic head.

[0031] The end cover 9, the right end cover 19, the left end cover 26 and the cover 30 are the servo valve shell, which is used for fixing the internal parts of the servo valve or protecting the servo valve.

[0032] The electric displacement sensor LVDT is connected with the LVDT modem and the servo amplifier outside the servo valve in sequence, the LVDT modem completes the signal solution of the LVDT, and feeds back to the servo amplifier, the servo amplifier outputs the bidirectional current to the servo valve, and realizes the closed loop control of the servo valve through the position feedback.

[0033] The linear motor 1 replaces the torque motor of the traditional servo valve, and the electric displacement sensor LVDT replaces the feedback rod of the traditional servo valve, and the spring tube and the feedback rod structure are omitted.

[0034] The contents not described in detail in the specification belong to the prior art known to the person skilled in the art. It is obvious for the person skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and the present application can be realized in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting from any point of view, the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application.

Claims

1. A double-nozzle flapper type electric feedback servo valve driven by a linear motor, characterized in that: The servo valve includes a drive stage, a pre-stage, and a power stage, wherein: The driving stage comprises a linear motor (1), a connecting rod (4), an electrical connector (2), a motor base (7), and an end cover (9); The pre-stage includes a baffle (10), a joint bearing (12), a nozzle (14), and a first-stage seat (13); The power stage includes a valve core (22), a magnetic head connecting rod (25), an electric displacement sensor LVDT, a housing (21), a right end cover (19), a left end cover (26), and a cover (30); The linear motor (1) is connected to a connecting rod (4), the connecting rod (4) is connected to the upper end of a baffle (10), and the baffle (10) deflects around a joint bearing (12) to form a lever with the joint bearing (12) as a fulcrum; The linear motion of the linear motor (1) and the connecting rod (4) is converted into the deflection of the baffle (10), and the output torque is amplified by the lever principle; There are two nozzles (14), which are symmetrically distributed on both sides of the baffle (10) and are press-fitted to the lower end of the joint bearing (12). The valve core (22) is fixed below the nozzle (14); The deflection of the baffle (10) changes the gap between the nozzle (14) and the left and right sides of the baffle (10), thereby realizing variable throttling of the spray stop. The generated pressure difference acts on the left and right end surfaces of the valve core (22), driving the valve core (22) to move; The electric displacement sensor LVDT comprises an LVDT sleeve (27) and an LVDT body (28), wherein the LVDT sleeve (27) is mounted on the surface of the left end cover (26), and the LVDT body (28) is mounted outside the LVDT sleeve (27); The magnetic head connecting rod (25) is located on one end surface of the valve core (22), and the magnetic head of the magnetic head connecting rod (25) is located at one end of the connecting rod close to the body of the electric displacement sensor LVDT; The electric displacement sensor LVDT is used to detect the position of the valve core (22).

2. A double-nozzle flapper type electric feedback servo valve driven by a linear motor according to claim 1, characterized in that: The linear motor (1), connecting rod (4), and electrical connector (2) are mounted on a motor seat (7); the baffle (10), joint bearing (12), and nozzle (14) are mounted on a first-stage seat (13); the valve core (22), magnetic head connecting rod (25), and electric displacement sensor LVDT are mounted on a housing (21); the motor seat (7), first-stage seat (13), and housing (21) are connected in sequence for fixing the structure and the oil circuit.

3. The double-nozzle flapper type electric feedback servo valve driven by a linear motor according to claim 1, characterized in that: The electrical connector (2) is used to connect a circuit, and the ratio of the extension and contraction displacement of the linear motor (1) to the control current is linear.

4. The double-nozzle flapper type electric feedback servo valve driven by a linear motor according to claim 1, characterized in that: The upper end of the baffle (10) is fixed to the connecting rod (4) via internal and external thread screws (5) and a locking nut (6).

5. The double-nozzle flapper type electric feedback servo valve driven by a linear motor according to claim 1, characterized in that: The pre-stage adopts a hydraulic bridge circuit, and its throttling elements include a pair of throttles (31) and a pair of nozzles (14); the throttles (31) are symmetrically located at both ends of the filter element (32); the high-pressure oil enters the throttle (31) after being filtered by the filter element (32), and then flows through the nozzle (14).

6. The double-nozzle flapper type electric feedback servo valve driven by a linear motor according to claim 1, characterized in that: The outlet of the nozzle (14) is an overflow chamber (38), and a damping block (37) with a small hole is arranged inside the overflow chamber (38) for adjusting the reference pressure of the hydraulic bridge circuit; the small hole of the damping block (37) has different apertures, and the aperture is changed according to working conditions.

7. The double-nozzle flapper type electric feedback servo valve driven by a linear motor according to claim 1, characterized in that: A sealing ring and a plug are provided inside the servo valve to achieve isolation or sealing of the oil circuit; and the electric displacement sensor LVDT sleeve (27) is used to achieve oil isolation between the LVDT body (28) and the magnetic head of the magnetic head connecting rod (25).

8. The double-nozzle flapper type electric feedback servo valve driven by a linear motor according to claim 1, characterized in that: The end cover (9), the right end cover (19), the left end cover (26) and the cover (30) are servo valve housings, which are used to fix the internal parts of the servo valve or to protect the servo valve.

9. The double-nozzle flapper type electric feedback servo valve driven by a linear motor according to claim 1, characterized in that: The electric displacement sensor LVDT is connected to the LVDT modem and servo amplifier outside the servo valve in sequence. The electric displacement sensor LVDT modem completes the LVDT signal solution and feeds back to the servo amplifier. The servo amplifier outputs bidirectional current to the servo valve, and realizes closed-loop control of the servo valve through position feedback.

10. The double-nozzle flapper type electric feedback servo valve driven by a linear motor according to claim 1, characterized in that: The linear motor (1) replaces the torque motor of a traditional servo valve, and the electric displacement sensor LVDT replaces the feedback rod of a traditional servo valve, thereby eliminating the need for a spring tube and feedback rod structures.

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