SU792002A1 - Digital electrohydraulic drive - Google Patents

Description

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The invention relates to digital electrically-controlled electro-hydraulic actuators, representing an extensive class of discrete actuators used in various automatic control systems (CDS). One of the directions is the creation of a discrete electro-hydraulic drive to digital ACS consisting of 10 of a stepper electric motor (SED), a throttling hydraulic distributor (DGR) of the hydraulic cylinder and mechanical feedback, which together form a follow-up linear hydraulic drive with mechanical feedback.

A known electro-hydraulic follow-up system with a hydromechanical wave former in a direct control circuit, which eliminates the influence of the energy of the fast-rotating parts of the engine and switchgear 1.

The closest technical solution to this is a digital electro-hydraulic drive containing a stepper motor (VDD) connected to a control channel and a hydromechanical amplifier with a power amplifier.

for example, made in the form of a wave reducer with a jet tube, a throttle control valve (DGR) of a spool type, connected through a screw-nut transmission to a hydromechanical power amplifier and hydraulically to a linear hydraulic motor, the rod of which is connected to a feedback lever 12J ,

In such a drive, there is a backlash in the mechanical feedback circuit, which leads to a decrease in the stable operation of the drive under inertial load.

When assembling such a drive, it is necessary to obtain the required force for changing the throttling hydraulic distributor either by increasing the gear ratio in the kinematic connections established between the SED shaft and the DGR, or by increasing the SED output power. In turn, an increase in the gear ratio in kinematic transmissions will lead to a decrease in the quality of the drive in speed at a fixed pickup frequency for a given type of PED. Increase permutation effort due to increased output power

SED is not always possible due to a number of restrictions.

The purpose of the invention is to improve the dynamic characteristics due to a significant increase in the switching force on the GDR-following linear hydraulic drive with mechanical feedback and to improve the positioning accuracy.

The essence of the invention is that in it the feedback lever is connected to the screw of the screw drive.

At the same time, the shaft of the SED is completely unloaded and only fulfills the specified load angle Oez, which is strictly worked out by the wave gearbox, taking into account the transmission coefficient. The torque generated by the WAVE gear reducer is realized due to the dynamics of the liquid jets flowing out of the nozzles under pressure equal to the pressure in the pressure hydraulic line and due to the reduction of the wave reducer. The position of the rotation of the wave reducer sets the SED which is then transformed into a linear movement by a pair of screw-nuts.

The drawing shows a diagram of a digital, electro-hydraulic drive consisting of the following parts and assemblies: 1 - case of the following linear hydraulic drive; 2 stepping motor (SHED); 3 - electronic switchboard (EC), which forms the signal to the control channel SED; 4 - digital control machine (TsUM) or computer, microprocessor; 5 - piston of a linear hydraulic engine-power cylinder with rods located on both piston storons; 6 - throttle directional valve, 4-edge, spool-type (DGR); 7 - hydrolines connecting the right cavity of the follow- ing linear hydraulic drive with DGR; 8 - hydrolines connecting the left cavity of the follow-up linear hydraulic drive with the horizontal resonance; 9 - jet tube with two nozzles (wave generator); 10 - deformable driven gear wave gear; 11 - fixed gear wheel wave gear; 10 and 11 - together form a wave gear reducer; 12 - the right cavity of the power cylinder; 13 - the left cavity of the power cylinder; 14 a lever (mechanical) feedback of a follow-up linear hydraulic drive; 15 - screw; 16 - a piston with a rod containing a nut; (15 and 16 - all sets of cc-set gear screw;); PH and PC - connection, respectively, of pressure and drain lines to the drive.

The digital electrohydraulic drive consists of SHED 2, which

through the coupling is rigidly connected with a string tube-9, having two nozzles located in the same plane at an angle of -180 °. The jet tube is placed in the casing of the follow- ing linear hydraulic drive 1 in the sliding bearings and is connected through internal channels to the pressure hydroline Rn. The jet tube has the ability to rotate in the body of the hydraulic drive in the sliding bearings, which are also sealing devices. The jet tube is located inside the driven gear 10 of the wave gear with a small gap between the nozzles and the latter. Under the action of a force, the driven gear can be deformed and meshes with the fixed gear 11. The driven gear has a number of teeth 2 and a fixed wheel has a number of teeth 2 + 1, and together they comprise a wave gear reducer. The driven gear is rigidly connected to the screw 15, which is engaged with the nut, which is placed in the piston with the rod 16. The screw 15 has the ability to enter the rod. A screw and a piston with a stem containing a nut together constitute a screw-nut kinematic pair that converts the rotational motion of the screw into reciprocating moving pistons with the stem. The piston is hinged through the rod to the mechanical feedback lever of the follow- ing linear hydraulic actuator. In the housing 1 of the hydraulic actuator, a throttle valve 6 is placed, to which two hydraulic lines are supplied — Pornna Rn and Pc drain. Two hydraulic lines 7 and 8, which connect the right 12 and left 13 cavities of the hydraulic drive, respectively, depart from the DGR. In the housing 1 of the hydraulic piston placed with rods 5 located on both sides of the piston. The housing 1 and the piston with the rods 5 form a power cylinder with a double-sided rod. The DGR is pivotally connected to the mechanical feedback lever, which in turn is also pivotally connected to the piston rod 5. The DGR, hydraulic cylinder and lever mechanical feedback together constitute the following linear hydraulic actuator. The electronic control unit, which generates signals at the PED, consists of a digital control machine 4 and an electronic switch 3.

Digital electro-hydraulic drive works as follows.

The control pulses from the CUM 4 are fed to the electronic switch 3, which forms the control algorithm for SED 2. When receiving a command from the electronic switch, the SED turns at a certain angle clockwise or counterclockwise according to the command, and it rotates the jet tube with two nozzles, to which the fluid from the pressure line is supplied. The fluid, emerging from the nozzles of the jet tube, acts on the driven eubchatuy wheel, which under the action of the forces from the jets is deformed and, being engaged with the stationary gear wheel, moves at a certain angle. The fluid flowing out of the nozzles and acting on the driven gear then drains from the cavity of the wave reducer into the drainage line. The nozzle jet tube is a wave generator. The follower gear with the rotation of the jet tube is also rotated to a certain angle, taking into account the transmission coefficient, the wave gear reducer. The driven gear rotates the screw 15, mounted in the rolling bearing, through rigid fastening. The rotation of the screw causes the piston to move in translation with the rod 16. The movement of the piston through the rod causes the movement of the mechanical feedback lever 14 of the follow-up linear hydraulic drive. The feedback lever moves relative to its fastening in the stem of part 5. When the lever moves relative to the fixing point in the stem of part 5, the throttle control valve b is displaced relative to its neutral position, which causes the cavities 12 and 13 to connect to the pressure valve and drain hydrolines through internal hydraulic lines 7 and 8. Connecting cavities 12 and 13 with pressure and drain hydroline respectively will depend on the movement of the feedback lever clockwise or counterclockwise, which will cause a differential pressure Eni on the piston 16 and moving the latter. Moving the piston 5 will cause the feedback lever pinning point on the rod of part 5 to move relative to its fixation with part 16 and, in turn, will result in the return of the DGR to the neutral position. Returning the DGR to the neutral position will result in overlapping of the hydraulic lines 7 and 8 connecting the right and left cavities of the hydraulic drive, and stopping the piston 5. Therefore, turning the SED shaft through a certain angle will cause a strictly defined movement of the stem of the follow-up hydraulic drive.

The technical and economic efficiency of the proposed drive consists in increasing the Q-factor, since the shaft of an SED is not loaded with any forces. When assembling a discrete electro-hydraulic linear drive consisting of SHED, DGR, representing 4-edge spool, hydraulic cylinders, in total representing the following linear hydraulic actuator with lever mechanical feedback, there are no backlash joints in the form of a screw, a rail gear and etc. at

The feedback circuit does not have to be resolved in the choice of the required force on the GDR due to the speed of displacement of the latter.

Claims (2)

1. USSR author's certificate according to the application No. 2152475 / 18-24, cl. F 15 B 1J / 12, 1965. 2. Discrete control electro-hydraulic drive, ed. G. N. Posokhina, M, Energie, 1975, p.21 (prototype). Aa