Closed type jet pipe electro-hydraulic servo valve structure capable of preventing oil pollution

Abstract

This invention relates to a closed-loop anti-return oil contamination jet tube electro-hydraulic servo valve structure. The valve core has a U-shaped groove for mounting a feedback spring assembly. After the valve core is installed in the valve sleeve, a gap seal is formed between the valve core and the inner wall of the valve sleeve, sealing and isolating the valve body's return oil chamber from the U-shaped groove cavity of the valve core. A gap seal connection is used between the valve sleeve and the valve body to isolate the cavity containing the nozzle and receiver from the valve body's return oil chamber. The valve body has an independent flow channel that guides the jet oil from the nozzle to the oil filter, and then introduces the oil into the valve body's return oil port through the filter. This invention designs a sealed isolation structure to isolate the feedback spring assembly from the servo valve's return oil flow field cavity, preventing turbulent flow from directly interfering with the feedback spring assembly and improving the force state of the feedback rod. The separate flow channel that guides the jet oil output from the nozzle to the return oil port and the addition of an oil filter structure effectively prevents the servo valve's jet stage (nozzle and receiver) from being contaminated by return oil, improving the servo valve's reliability and service life.

Description

Technical Field

[0001] This invention relates to an electro-hydraulic servo control element in hydraulic engineering, and more particularly to a jet tube electro-hydraulic servo valve structure. Background Technology

[0002] Electro-hydraulic servo valves are precision hydraulic control components with internal orifice sizes down to the micrometer level, making them highly susceptible to clogging by contaminants in the hydraulic fluid, leading to complete valve malfunction. Currently, in the domestic servo valve field, the 609 Institute has conducted extensive research on contamination protection for nozzle-flap type two-stage servo valves, using methods such as adding filters and check valves to protect the nozzle, return port, and bottom oil passage. Xi'an Haisheng Aviation Technology Co., Ltd. has optimized the structure of the nozzle-flap valve baffle, designing the baffle and nozzle with a ball joint fit, making it difficult for contaminants to enter. While these inventions can prevent return oil contamination to some extent, they do not isolate the pilot stage oil passage from the return oil chamber, failing to eliminate the influence of the return oil turbulence field on the feedback components.

[0003] Compared to nozzle-baffle type electro-hydraulic servo valves, the pilot stage of jet pipe electro-hydraulic servo valves already has strong anti-contamination capabilities.

[0004] The principle of the jet tube electro-hydraulic servo valve is as follows: Figure 1 As shown, it mainly consists of a torque motor, a jet amplifier, a spool valve assembly, and a feedback assembly. The torque motor adopts a permanent magnet structure, with a Bourdon tube supporting the armature jet tube assembly and isolating the motor from the hydraulic system. The preamplifier stage is a jet amplifier, which consists of a jet tube and a receiver.

[0005] Its working principle is as follows: When a control current is input to the motor coil, the control magnetic flux generated on the armature interacts with the permanent magnet flux, thus generating a torque on the armature. This torque causes the armature, Bourdon tube, and nozzle assembly to deflect by a small angle proportional to the torque. The deflection of the high-speed jet through the nozzle causes the pressure in one chamber of the receiver to increase and the pressure in the other chamber to decrease. A pressure difference is formed across the valve core connecting these two chambers. The valve core moves until the torque generated by the feedback assembly balances the motor torque, causing the nozzle to return to a position near the midpoint between the two receivers. At this point, the displacement of the valve core is proportional to the magnitude of the control current, and the valve's output flow rate is proportional to the control current.

[0006] Currently, the pilot stage structure (jet stage) of the jet tube electro-hydraulic servo valve mainly consists of a torque motor jet tube, nozzle, receiver, feedback spring assembly, clamping screw, and spool valve assembly (including valve body) (as follows). Figure 2 (As shown).

[0007] The existing structure is an open cavity structure. Hydraulic oil is supplied through the inlet to high-pressure oil. After being filtered by an oil filter, the high-pressure oil passes through a motor jet pipe and is ejected through a nozzle to create a pressure difference between the two chambers of the servo valve receiver, driving the servo valve spool to move. Excess hydraulic oil flows back to the return chamber along the spool valve passage (see...). Figure 3 The servo valve jet stage of this structure is directly connected to the hydraulic system's return oil circuit, making it an open structure.

[0008] Therefore, this structure has the following drawbacks:

[0009] 1) The jet stage, composed of the nozzle and receiver of the electro-hydraulic servo valve, is susceptible to contamination from the return oil, which can cause the servo valve to malfunction and fail to work. Due to its open structure, the jet stage is directly connected to the return oil circuit of the hydraulic system. However, most hydraulic systems only install oil filters on the supply line for protection, and no filters are installed on the return oil circuit. When the system stops, if there is back pressure in the return oil or the oil level in the tank is higher than the mounting surface of the servo valve, the oil in the return oil tank will flow back to the return port of the servo valve. The nozzle and receiver orifice diameter is only 0.2mm, which is easily contaminated by pollutants, causing the nozzle or receiver orifice to become contaminated and clogged, resulting in functional failure.

[0010] 2) Since the feedback spring assembly is directly installed in the cavity where the nozzle jet and the return oil flow field of the slide valve meet, when the high pressure oil has a large return oil flow rate during the operation of the slide valve, it generates a turbulent flow field together with the nozzle jet, which interferes with the normal operation of the feedback spring assembly, resulting in a decrease in the static control accuracy of the servo valve. In severe cases, it can cause the servo valve to resonate or the feedback spring assembly to break. Summary of the Invention

[0011] The present invention provides a closed-loop anti-return oil contamination jet tube electro-hydraulic servo valve structure, which can effectively prevent the servo valve jet stage (nozzle, receiver) from being contaminated by return oil, thereby improving the servo valve's anti-contamination capability; at the same time, it improves the stress state of the servo valve feedback spring assembly, enhances the servo valve's control accuracy, and improves the servo valve's reliability and service life.

[0012] To achieve the above objectives, the technical solution of the present invention is: a closed-loop anti-return oil contamination jet pipe electro-hydraulic servo valve structure, including a servo valve torque motor, valve core, valve sleeve, valve body, nozzle, receiver, and feedback spring assembly. The nozzle and receiver are provided with a U-shaped groove for installing the feedback spring assembly. After the valve core is installed in the valve sleeve, it forms a gap seal with the inner wall of the valve sleeve, sealing and isolating the return oil chamber of the valve body from the U-shaped groove cavity of the valve core. The valve sleeve and the valve body are connected by a gap seal, isolating the cavity where the nozzle and receiver are located from the return oil chamber of the valve body. The valve body is provided with an independent flow channel for guiding the jet oil from the nozzle to the oil filter, and introducing the oil into the return oil port of the valve body through the oil filter.

[0013] Furthermore, the feedback spring assembly is installed in the valve core U-shaped groove, which is sealed and isolated from the valve body's oil return chamber. This avoids interference from turbulent flow fields, thereby improving the control accuracy, reliability, and service life of the servo valve.

[0014] Furthermore, the end of the feedback spring assembly is inserted into the valve core slot, and two clamping screws clamp the end of the feedback spring assembly through the threaded connection inside the valve core, thereby connecting the feedback spring assembly and the valve core.

[0015] Furthermore, when the return oil pressure exceeds the pilot stage pressure, the return oil medium is filtered and blocked by the oil filter, ensuring that the nozzle and receiver are not contaminated.

[0016] The beneficial effects of this invention are:

[0017] 1) The feedback spring assembly is sealed and isolated from the return oil chamber of the servo valve. A separate flow channel is designed to guide the jet oil output from the nozzle to the return oil port and an oil filter structure is added to effectively prevent the jet stage (nozzle, receiver) of the servo valve from being contaminated by the return oil, thereby improving the reliability and service life of the servo valve.

[0018] 2) The designed sealed isolation structure isolates the feedback spring assembly from the return oil flow field cavity of the servo valve slide valve, preventing the turbulent flow field from directly interfering with the feedback spring assembly and improving the force state of the feedback rod.

[0019] 3) Improved force state of feedback spring assembly, enhancing control accuracy of servo valve. Attached Figure Description

[0020] Figure 1 Schematic diagram of the working principle of the electro-hydraulic servo valve for jet tubes;

[0021] Figure 2 This is a schematic diagram of the pilot stage structure of a jet tube electro-hydraulic servo valve;

[0022] Figure 3 This is a schematic diagram of the hydraulic oil flow direction in the existing structure.

[0023] Figure 4 This is a schematic diagram of the closed-loop anti-return oil contamination jet tube electro-hydraulic servo valve structure of the present invention.

[0024] Figure 5 for Figure 4 Left sectional view;

[0025] In the diagram: 1-Torque motor, 2-Nozzle, 3-Feedback spring assembly, 4-Valve body, 5-Valve sleeve, 6-Valve core, 7-Oil filter, 8-Clamping screw. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] like Figure 4 As shown in Figure 5, a structure for preventing backflow contamination of an electro-hydraulic servo valve includes a torque motor 1, a nozzle 2, a feedback spring assembly 3, a valve body 4, a valve sleeve 5, a valve core 6, an oil filter 7, and a clamping screw 8.

[0028] The torque motor 1, nozzle 2, and feedback spring assembly 3 are assembled into a component and installed in the valve body 4. The end of the feedback spring assembly 3 is inserted into the slot of the valve core 6. Two clamping screws 8 clamp the end of the feedback spring assembly 3 through the threaded connection inside the valve core 6, thus connecting the feedback spring assembly 3 to the valve core 6. The slot of the valve core 6 for installing the feedback spring assembly 3 is designed as a U-shaped slot. After being installed in the valve sleeve 5, it forms a gap seal with the inner wall of the valve sleeve 5, sealing and isolating the oil return chamber of the valve body 4 from the U-shaped slot cavity of the valve core 6. At the same time, the valve sleeve 5 also uses a gap seal when installed in the valve body 4 to seal and isolate the nozzle 2. The receiver 3 cavity is isolated from the return oil cavity of the valve body 4. The valve body 4 is designed with an independent flow channel to guide the oil jet from the nozzle 2 to the oil filter 7. The oil is then introduced into the return oil port of the valve body 4 through the oil filter 7. When the return oil pressure is greater than the pilot stage pressure, the return oil medium is filtered and blocked by the oil filter 7, ensuring that the nozzle 2 and receiver are not contaminated. At the same time, the feedback spring assembly 3 is installed in the U-shaped slot of the valve core 6, which is sealed and isolated from the return oil cavity of the valve body 4. This avoids interference from the turbulent flow field, improves the control accuracy of the servo valve, and enhances the reliability and service life of the servo valve.

Claims

1. A closed-loop anti-return oil contamination jet pipe electro-hydraulic servo valve structure, comprising a servo valve torque motor, valve core, valve sleeve, valve body, nozzle, receiver, and feedback spring assembly, characterized in that: The valve core has a U-shaped slot for installing the feedback spring assembly. After the valve core is installed in the valve sleeve, it forms a gap seal with the inner wall of the valve sleeve, sealing and isolating the valve body's oil return chamber from the U-shaped slot cavity of the valve core. The valve sleeve and valve body are connected by a gap seal, isolating the cavity where the nozzle and receiver are located from the valve body's oil return chamber. The valve body has an independent flow channel for guiding the nozzle-jet oil to the oil filter, and the oil is introduced into the valve body's oil return port through the oil filter. The feedback spring assembly is installed in the valve core's U-shaped slot, which is sealed and isolated from the valve body's oil return chamber, avoiding interference from turbulent flow fields and improving the control accuracy, reliability, and service life of the servo valve. The end of the feedback spring assembly is inserted into the valve core's slot, and two clamping screws clamp the end of the feedback spring assembly through the threaded connection inside the valve core, realizing the connection between the feedback spring assembly and the valve core.

2. The closed-loop anti-return oil contamination jet tube electro-hydraulic servo valve structure according to claim 1, characterized in that: When the return oil pressure exceeds the pilot stage pressure, the return oil medium passes through the oil filter to block contaminants, ensuring that the nozzle and receiver are not contaminated.

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