GB2117931A - Electro-hydraulic servo valves - Google Patents

Electro-hydraulic servo valves Download PDF

Info

Publication number
GB2117931A
GB2117931A GB08306619A GB8306619A GB2117931A GB 2117931 A GB2117931 A GB 2117931A GB 08306619 A GB08306619 A GB 08306619A GB 8306619 A GB8306619 A GB 8306619A GB 2117931 A GB2117931 A GB 2117931A
Authority
GB
United Kingdom
Prior art keywords
jewel
electro
nozzle
hydraulic servo
flapper
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.)
Withdrawn
Application number
GB08306619A
Other versions
GB8306619D0 (en
Inventor
Dennis William Parker
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Dowty Hydraulic Units Ltd
Original Assignee
Dowty Hydraulic Units Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Dowty Hydraulic Units Ltd filed Critical Dowty Hydraulic Units Ltd
Priority to GB08306619A priority Critical patent/GB2117931A/en
Publication of GB8306619D0 publication Critical patent/GB8306619D0/en
Publication of GB2117931A publication Critical patent/GB2117931A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15C—FLUID-CIRCUIT ELEMENTS PREDOMINANTLY USED FOR COMPUTING OR CONTROL PURPOSES
    • F15C3/00—Circuit elements having moving parts
    • F15C3/10—Circuit elements having moving parts using nozzles or jet pipes

Abstract

An electro-hydraulic servo valve of either the moving-flapper type or the moving-jet type has any one or more of the following features:- a) a nozzle in the form of a jewel, b) a restrictor, in the flow-passage to a nozzle, in the form of a jewel, and c) a bearing, in the form of a jewel, associated with the valve spool, for engagement with a feed-back wire. t

Description

SPECIFICATION Electro-hydraulic servo valves This invention relates to electro-hydraulic servo valves.
One form of electro-hydraulic servo valve utilises a nozzle or nozzles, the flow of liquid from which is controlled by a flapper. The flapper is caused to move from a null position, by means of an electrical force motor when the latter is energised, towards or away from a nozzle in order to increase or decrease the obturating effect which the flapper has on liquid issuing from the nozzle orifice.
It is essential for such a nozzle to have an accurately-profiled shape with a sharp edge which lies in a plane parallel to the surface of the flapper when the latter is in its null position; otherwise the ability of the flapper accurately to control the flow of liquid from the nozzle orifice is impaired.
Furthermore, because of erosion which can occur on the edge of the nozzle due to a highvelocity flow of liquid, it has been necessary to make the nozzles from high-quality steels and beryllium coppers.
As a consequence nozzles for electro-hydraulic servo valves are expensive.
In such an electro-hydraulic servo valve the position of a valve spool is changed by controlling the flow of liquid from the nozzles. It is customary to use in such forms of servo valve a spring wire which is rigidly fixed at one end to the flapper and is associated, at its other end, with the valve spool so that it can move, with the valve spool, with respect to its fixed end. As the valve spool moves from its null position, consequent upon movement of the flapper from its null position, the end of the spring wire on the valve spool also moves, bending the wire and providing a feedback signal.
One such valve is described in U.K. Patent Specification No. 923839.
As shown in that patent specification, the end of the wire located on the valve spool has an accurate spherical shape which may be an accurately-made ball, which fits in an endless groove formed in the valve spool.
In practice, it is necessary to produce in the valve spool an endless groove which has the required uniform size, shape and surface finish.
For, if it is not so, the spherical end of the wire may have a tight fit when it is within one part of the groove and may have a clearance fit when it is within another part of the groove. Both can impair the performance of the servo valve and the latter can also cause accelerated wear of the parts.
It is an object of this invention to provide an improved electro-hydraulic servo valve.
According to this invention an electro-hydraulic servo valve has a nozzle made from a jewel.
Such a nozzle has a high degree of resistance to erosion to liquid flowing through and out of it at a high velocity, can be readily manufactured with the necessary high degree of accuracy and surface finish, inciuding a substantially sharp edge if necessary, and, if the jewel is an industrial jewel, is cheaper than those hitherto used.
With nozzles used previously, it has been necessary accurately to position opposed nozzles, in relation to the flapper, by a manual adjustment.
This is a precision operation which requires a high degree of skill from an operator. Nozzles made from jewels can readily be positioned accurately in and, say, cemented to, a suitable nozzle holder, which can in turn, if desired, be positioned accurately in another part of the valve and a suitably-machined flapper can then more easily be positioned accurately between the two nozzles without any need for so-called "nozzle-pushing", the technique previously used for positioning nozzles with respect to a flapper.
An electro-hydraulic servo valve may have a restrictor which restricts the flow of liquid to a nozzle. According to this invention, such a restrictor may be a jewel and will have a high degree of resistance to erosion due to liquid flow at a high velocity, can be readily manufactured to the necessary high degree of accuracy and, if the jewel is an industrial jewel, will be cheaper than those hitherto used.
Also according to this invention the feed-back wire of an electro-hydraulic servo valve is associated with the valve spool by way of a jewel bearing.
Conveniently, the jewel bearing can be in the form of a hollow tube, within which the spherical end of the feed-back wire can fit, and the hollow tube can fit in a suitable hole which can be easily machined in the valve spool.
Such a hollow tube can readily be finished to a high degree of accuracy and of surface finish. Its size can be chosen to match a certain size of high precision ball which can be fitted to the end of the feed-back wire. The quality and hardness of the jewel bearing reduces wear caused by any sliding between the feed-back wire and the spool.
If damage does occur to the jewel bearing, it can readily be removed from the valve spool and replaced. Conveniently, the jewel will be an industrial jewel which is relatively inexpensive.
Although the illustrative electro-hydraulic servo valves described above have been of the so called nozzle/flapper type, those electro-hydraulic servo valves of the so-called moving-jet type could also have nozzles and/or restrictors and/or feed-back bearings in the form of jewels.
Claim
1. An electro-hydraulic servo valve having any one or more of the following features:-
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (1)

  1. **WARNING** start of CLMS field may overlap end of DESC **.
    SPECIFICATION Electro-hydraulic servo valves This invention relates to electro-hydraulic servo valves.
    One form of electro-hydraulic servo valve utilises a nozzle or nozzles, the flow of liquid from which is controlled by a flapper. The flapper is caused to move from a null position, by means of an electrical force motor when the latter is energised, towards or away from a nozzle in order to increase or decrease the obturating effect which the flapper has on liquid issuing from the nozzle orifice.
    It is essential for such a nozzle to have an accurately-profiled shape with a sharp edge which lies in a plane parallel to the surface of the flapper when the latter is in its null position; otherwise the ability of the flapper accurately to control the flow of liquid from the nozzle orifice is impaired.
    Furthermore, because of erosion which can occur on the edge of the nozzle due to a highvelocity flow of liquid, it has been necessary to make the nozzles from high-quality steels and beryllium coppers.
    As a consequence nozzles for electro-hydraulic servo valves are expensive.
    In such an electro-hydraulic servo valve the position of a valve spool is changed by controlling the flow of liquid from the nozzles. It is customary to use in such forms of servo valve a spring wire which is rigidly fixed at one end to the flapper and is associated, at its other end, with the valve spool so that it can move, with the valve spool, with respect to its fixed end. As the valve spool moves from its null position, consequent upon movement of the flapper from its null position, the end of the spring wire on the valve spool also moves, bending the wire and providing a feedback signal.
    One such valve is described in U.K. Patent Specification No. 923839.
    As shown in that patent specification, the end of the wire located on the valve spool has an accurate spherical shape which may be an accurately-made ball, which fits in an endless groove formed in the valve spool.
    In practice, it is necessary to produce in the valve spool an endless groove which has the required uniform size, shape and surface finish.
    For, if it is not so, the spherical end of the wire may have a tight fit when it is within one part of the groove and may have a clearance fit when it is within another part of the groove. Both can impair the performance of the servo valve and the latter can also cause accelerated wear of the parts.
    It is an object of this invention to provide an improved electro-hydraulic servo valve.
    According to this invention an electro-hydraulic servo valve has a nozzle made from a jewel.
    Such a nozzle has a high degree of resistance to erosion to liquid flowing through and out of it at a high velocity, can be readily manufactured with the necessary high degree of accuracy and surface finish, inciuding a substantially sharp edge if necessary, and, if the jewel is an industrial jewel, is cheaper than those hitherto used.
    With nozzles used previously, it has been necessary accurately to position opposed nozzles, in relation to the flapper, by a manual adjustment.
    This is a precision operation which requires a high degree of skill from an operator. Nozzles made from jewels can readily be positioned accurately in and, say, cemented to, a suitable nozzle holder, which can in turn, if desired, be positioned accurately in another part of the valve and a suitably-machined flapper can then more easily be positioned accurately between the two nozzles without any need for so-called "nozzle-pushing", the technique previously used for positioning nozzles with respect to a flapper.
    An electro-hydraulic servo valve may have a restrictor which restricts the flow of liquid to a nozzle. According to this invention, such a restrictor may be a jewel and will have a high degree of resistance to erosion due to liquid flow at a high velocity, can be readily manufactured to the necessary high degree of accuracy and, if the jewel is an industrial jewel, will be cheaper than those hitherto used.
    Also according to this invention the feed-back wire of an electro-hydraulic servo valve is associated with the valve spool by way of a jewel bearing.
    Conveniently, the jewel bearing can be in the form of a hollow tube, within which the spherical end of the feed-back wire can fit, and the hollow tube can fit in a suitable hole which can be easily machined in the valve spool.
    Such a hollow tube can readily be finished to a high degree of accuracy and of surface finish. Its size can be chosen to match a certain size of high precision ball which can be fitted to the end of the feed-back wire. The quality and hardness of the jewel bearing reduces wear caused by any sliding between the feed-back wire and the spool.
    If damage does occur to the jewel bearing, it can readily be removed from the valve spool and replaced. Conveniently, the jewel will be an industrial jewel which is relatively inexpensive.
    Although the illustrative electro-hydraulic servo valves described above have been of the so called nozzle/flapper type, those electro-hydraulic servo valves of the so-called moving-jet type could also have nozzles and/or restrictors and/or feed-back bearings in the form of jewels.
    Claim
    1. An electro-hydraulic servo valve having any one or more of the following features:- (a) a nozzle or nozzles made from a jewel, (b) a restrictor made from a jewel, and (c) a bearing for a feed-back wire in the form of a jewel.
GB08306619A 1982-03-19 1983-03-10 Electro-hydraulic servo valves Withdrawn GB2117931A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08306619A GB2117931A (en) 1982-03-19 1983-03-10 Electro-hydraulic servo valves

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB8208147 1982-03-19
GB8208148 1982-03-19
GB08306619A GB2117931A (en) 1982-03-19 1983-03-10 Electro-hydraulic servo valves

Publications (2)

Publication Number Publication Date
GB8306619D0 GB8306619D0 (en) 1983-04-13
GB2117931A true GB2117931A (en) 1983-10-19

Family

ID=27261524

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08306619A Withdrawn GB2117931A (en) 1982-03-19 1983-03-10 Electro-hydraulic servo valves

Country Status (1)

Country Link
GB (1) GB2117931A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2153110A (en) * 1984-01-28 1985-08-14 Rexroth Mannesmann Gmbh A servo-valve
EP0212873A1 (en) * 1985-08-08 1987-03-04 Sabre Safety Limited Positive pressure demand valves
DE3737143A1 (en) * 1987-11-02 1989-05-11 Rexroth Mannesmann Gmbh Servo valve

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB731298A (en) * 1951-11-30 1955-06-08 Mueller Wilhelm Improvements in or relating to articles having wear resistant outer surfaces and processes for making the same
GB984260A (en) * 1962-06-08 1965-02-24 Lucifer Sa Improvements in relation to single beat lift valves
GB1197899A (en) * 1966-11-30 1970-07-08 Goodrich Co B F Manufacture of Polyurethane Belting
GB1535441A (en) * 1976-02-04 1978-12-13 Hewlett Packard Gmbh Sample injection device for liquid chromatographs

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB731298A (en) * 1951-11-30 1955-06-08 Mueller Wilhelm Improvements in or relating to articles having wear resistant outer surfaces and processes for making the same
GB984260A (en) * 1962-06-08 1965-02-24 Lucifer Sa Improvements in relation to single beat lift valves
GB1197899A (en) * 1966-11-30 1970-07-08 Goodrich Co B F Manufacture of Polyurethane Belting
GB1535441A (en) * 1976-02-04 1978-12-13 Hewlett Packard Gmbh Sample injection device for liquid chromatographs

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2153110A (en) * 1984-01-28 1985-08-14 Rexroth Mannesmann Gmbh A servo-valve
US4624284A (en) * 1984-01-28 1986-11-25 Mannesmann Rexroth Gmbh Servovalve
EP0212873A1 (en) * 1985-08-08 1987-03-04 Sabre Safety Limited Positive pressure demand valves
DE3737143A1 (en) * 1987-11-02 1989-05-11 Rexroth Mannesmann Gmbh Servo valve

Also Published As

Publication number Publication date
GB8306619D0 (en) 1983-04-13

Similar Documents

Publication Publication Date Title
EP0066150B1 (en) Variable gain servo controlled directional valve
JPH0839281A (en) Laser cutter with focal position adjusting device
DE883082C (en) Probe device for a copy milling machine
JPS5854207A (en) Electronic fluid type servo valve device
JPH0424565B2 (en)
DE4113633C2 (en) Processing device
US5070898A (en) Metering valve
US4643590A (en) Guide system
GB2117931A (en) Electro-hydraulic servo valves
US3159170A (en) Web edge control device
EP3023647B1 (en) Servovalve jet pipe
JPH0919841A (en) Machine centering compensation actuator system
US4782860A (en) Magnetic flow control valve
US10760704B2 (en) Servovalve assembly
EP3412921B1 (en) Servovalve assembly
EP1016793B1 (en) Pressure controller
DE3105578C2 (en) Device for positioning a grinding wheel
US4391430A (en) Hydraulic servo control spool valve
RU2266438C1 (en) Hydraulic circuit for linear drive of tool slide
US3765437A (en) Hydraulic free-jet servo-valves
US3459402A (en) Tracer valve assembly
GB2124799A (en) Electro-hydraulic servo valve
US4854752A (en) Convertible print head
DE2922419A1 (en) Wear and cavitation resistant two=way valve - has ball and flow controlling seats made of corundum to resist corrosion and wear
EP0282454A2 (en) Device for adjusting the distance between or tool and a workpiece

Legal Events

Date Code Title Description
WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)