Title of Invention

"AN ELECTRO-HYDRAULIC PRESSURE CONTROL VALVE FOR PRECISE SPEED CONTROL OF INDUSTRIAL TURBINE"

Abstract

This invention relates to an electro - hydraulic pressure control valve for precise speed control of industrial turbines by delivering hydraulic oil to the valve comprising a permanent magnet torque motor (1), a pressure port (4), a control port (5) a drain port (6) and an electronic controller (8a) to process the input signal current for the torque motor characterized in that the torque motor armature fitted with flapper and connected to flapper nozzle (2), the flapper controlling the flapper nozzle gap proportionate to the signal current, the flapper nozzle (2) connected to a three land spool, (3) the nozzle chamber pressure of the nozzle (2) being transmitted to one end of the spool and the middle land of the said spool (3) controls the opening of the control port (5) and provided with a bias spring (7) for initial adjustment of pressure.

Full Text

This invention relates to an electro - hydraulic pressure control valve for precise speed control of industrial turbines for power generation. Presently mechanical governors are used extensively for the speed control of industrial turbines. There are disadvantages associated with the mechanical governors for speed control of Industrial turbines. One of the disadvantage of the present type of mechanical governors in that the speed control is not precise and maintains only an average speed depending on the load. Another disadvantage of the present type of mechanical governors is that the control is not linear and is moderately effective only within a narrow middle range. There is a trend exists for the channge over to electronic control from mechanical governors but no effective and improved control has yet been developed and being used in the speed control of industrial turbines. Therefore, the main,object of the present invention is to provide an effective and precise speed control of industrial turbines for power generation which utilises a combination of electronic and hydraulic pressure control. Another object of the present invention is to provide a torque motor with improved armature-fIexutre-fIapper assembly for developing torque proportional to current variations wherein a flexture provides the required restoring moment. Yet another object of the present invention is to provide flapper nozzle valve for the effective near pressure variations proportional to the flapper position and a spool valve wherein flow of oil is linear to the spool position. A further objection of the present invention is to provide and electronic circuit for supply of power to the electronic controller and a signal conditioning circuit for deriving the required feedback signal from pressure pick up as input of 4-20 mA control signal to the electronic controller to develop a suitable current to drive the torque motor. Yet a further object of the present invention is to provide a dynamic frequency of 6HZ for system. According to the present invention there is provided an electro-hydraulic pressure control valve for precise speed control of industrial turbines by delivering hydraulic to the valve comprising a permanent magnet torque motor, a pressure port, a control port a drain port and an electronic controller to process the input signal current for the torque motor characterized in that the torque motor armature fitted with flapper and connected to flapper nozzle, the flapper controlling the flapper nozzle gap proportionate to the signal current, flapper nozzle connected to a three land spool, the nozzle chamber pressure of the nozzle being transmitted to one end of the spool and the middle land of the said spool controls the opening of the control port and provided with a bias spring for initial adjustment of pressure. The nature of the invention, its objective and further advantages residing in the same will be apparent from the following description made with reference to non-limiting exemplary embodiments of the invention represented in the accompanying drawings: Fig.l shows the general configuration of the valve; Fig.2 shows the sectional view of the valve showing the configurations of various components; Fig.3 shows the details of electronic controller circutory; Fig.4 shows the performance curve of the control pressure and output flow. In accordance with the present invention the valve consists of a permanent magnet torque motor (1) to convert electric signal in to mechanical movement, a flapper nozzle valve (2) which works as a hydraulic amplifier, a pool valve (3) which controls the control pressure port (5) opening in direct proportion to the signal current and a pressure transducer to give the required feed-back. It has built in control electronics (8) comprising of connector (8) and electronic circuit (8a). The valve has a filter cover (9) to provide an access to the filter for its maintenance, by opening the cover. The valve has three hydraulic interfaces; (1) a pressure port (4) connected to hydraulic power source of 6-8 KSC pressure having minimum flow capacity of 20 liters per m in. and (2) a control port (5) connected to the driven device and (3) a drain port (6) connected to the reservoir. Details of electric connection is shown terminating a t the e I electrical 8a connector Input signal current of 4-20 mA is processed in the control electronics (8) which drives the torque motor (1).0n the armature of the torque motor is fitted a flapper which controls the flapper nozzle (2) gap proportionate to the signal current. The armature is held by a flexture which provides the restoring moment . Nozzle chamber pressure increases with the flapper movement and the pressure is communicated to one end of the spool (3) and makes it move. The spool (3) is a three land configuration and the middle land controls the opening of the control port (5). The spool (3) is loaded with a bias spring which can be used for initial adjustment (7) of pressure. A pressure transducer is connected to the control pressure which gives necessary feed back to the system. The armature, flexture tube and the flapper are so designed that the consistency is geometrical relations between these can be achieved with normal work skill. Machining of the armature ends and the flapper flats are done by electro discharge machining. During the process of invention two laboratory models were fabricated and tested and the results evaluated. Final refinements made on the critical functional elements and more precise results obtained. Detail technical data of these two laboratory models is given below: - Electrical : Inpu t supply: Power consumption Signal Inpu t: 18-32 VDC (24 VDC nominal) 4-20 mA in to 100 ohms (Output pressure increases with signal current) Hydraulie: Media : Supply pressure : FiItration : Vi scos i ty : Output Pressure : F I ow : Performance: L i near i ty: Hysteres is: Accuracy : Frequency response: Environment : Operating temperature Storage temperature ; Shock: Vibrat ion P hy s i c a I : Height: Base : Petroleum based turbine oil. (Servo Prime 46) 6-8 KSC 25 Microns absolute 8 to 400 Centistokes 1 to 4.5 KSC 12 to 18 liters per minute (max) (As per Pressure Vs.Flow graph - Fig. 5) 0.5% of full scale over full range 0.2% of full scale over full range {0.25% at ambient temperature of 15 to 50 degrees C. 1 % of fu1 r scale over full range. 4-6 Hz at SRC 15 to 50 degree C -40 to 85 degree C 50 g half sine for 0.005 sec. ( 18 puIses total) MIL-STD-810C (516.2-2 at 50 g) 18 to 500 Hz at 4.2 grms MIL - STD - 8 IOC ( 516.2-6 CURVE vV) 203 mm 165x165 mm The invention described hereinabove is in relation to non - limiting embodiment and as defined by the accompanying claims. WE CLAIM; 1. An electro-hydraulic pressure control valve for precise speed control of industrial turbines by delivering hydraulic oil to the valve comprising a permanent magnet torque motor (1), a pressure port (4), a control port (5), a drain port (6) and an electronic controller (8a) to process the input signal current for the torque motor characterized in that the torque motor armature fitted with flapper and connected to flapper nozzle (2). The flapper controlling the flapper nozzle gap proportionate to the signal current, the flapper nozzle (2) connected to a three land spool (3), the nozzle chamber pressure of the nozzle (2) being transmitted to one end of the spool and the middle land of the said spool (3) controls the opening of the control port (5) and provided with a bias spring (7) for intial adjustment of pressure. 2. An electro-hydraulic pressure control valve as claimed in claim 1 wherein the torque motor armature fitted with flapper, the said armature being held by a flexture to provide the restoring moment. 3. An electro-hydraulic pressure control valve as claimed in claim 1 wherein the nozzle chamber is connected to flapper movement of the armature for pressure control. 4. An electro-hydraulic pressure control valve for precise speed control of industrial turbines as hereinabove described an illustrated.

Documents:

1759-del-1997-abstract.pdf

1759-del-1997-claims.pdf

1759-del-1997-correspondence-others.pdf

1759-del-1997-correspondence-po.pdf

1759-del-1997-description (complete).pdf

1759-del-1997-drawings.pdf

1759-del-1997-form-1.pdf

1759-del-1997-form-19.pdf

1759-del-1997-form-2.pdf

1759-del-1997-form-3.pdf

1759-del-1997-gpa.pdf