GB2031616A – Control system for a valve
– Google Patents
GB2031616A – Control system for a valve
– Google Patents
Control system for a valve
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Info
Publication number
GB2031616A
GB2031616A
GB7927614A
GB7927614A
GB2031616A
GB 2031616 A
GB2031616 A
GB 2031616A
GB 7927614 A
GB7927614 A
GB 7927614A
GB 7927614 A
GB7927614 A
GB 7927614A
GB 2031616 A
GB2031616 A
GB 2031616A
Authority
GB
United Kingdom
Prior art keywords
piston
control
cartridge
spool
fluid
Prior art date
1978-08-16
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.)
Granted
Application number
GB7927614A
Other versions
GB2031616B
(en
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.)
Schwelm & Towler Hydraulics
Original Assignee
Schwelm & Towler Hydraulics
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.)
1978-08-16
Filing date
1979-08-08
Publication date
1980-04-23
1979-08-08
Application filed by Schwelm & Towler Hydraulics
filed
Critical
Schwelm & Towler Hydraulics
1980-04-23
Publication of GB2031616A
publication
Critical
patent/GB2031616A/en
1982-12-15
Application granted
granted
Critical
1982-12-15
Publication of GB2031616B
publication
Critical
patent/GB2031616B/en
Status
Expired
legal-status
Critical
Current
Links
Espacenet
Global Dossier
Discuss
Classifications
F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
F15B13/00—Details of servomotor systems ; Valves for servomotor systems
F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
F15B13/0401—Valve members; Fluid interconnections therefor
F15B13/0405—Valve members; Fluid interconnections therefor for seat valves, i.e. poppet valves
Description
1 GB 2 031 616 A 1
SPECIFICATION
A control system for a cartridge valve This invention relates to a control system for con- 70 trolling a cartridge valve for the purpose of influenc ing flow of fluid therethrough, for example when used as a throttle.
In multi-way valves with control spools, it is known that proportionality can be established be tween spool travel and an introduced signal as a result of the factthatthe position of the spool is associated with the equilibrium of the forces acting thereon, that is to say that by altering the force conditions, the spool travel is altered, because according to the basic laws of physics, the position of the spool necessarily always changes so that the forces acting thereon come into equilibrium again.
In this manner, a precise, sensitive positioning of the driven member is possible, as is necessary, for example, in a variety of transport and working machines. In a cartridge valve, that is to say a two-way built-in valve with only one control edge, it was hitherto only possible with great difficulty to provide a direct relation between an introduced signal and the cross-sectional area of flow freed thereby.
In contrast to spool valves, cartridge valves have only one control oil connection so that it is necessary to use methods now common in the spool technique in the cartridge technique, namely to combine one of the two main flow connections with the associated piston area or annular area with the necessary second control oil connection.
As a result of this combination this area is exposed 100 to all the pressure fluctuations of the main connec tion which means thatthese fluctuations have to be stabilized at the side of the opposite control oil connection in order to keep the cartridge piston in the required position.
This kind of regulations makes very heavy de mands on the quality of the regulating system.
The object of the invention is to provide a control system for displacing the piston of a cartridge valve by a specific amount, with simple means, in order to 11 free a very specific cross-sectional area of flow which is proportional to an introduced signal, as is already prior art forthe control of a spool.
According to the present invention there is pro vided a control system for a cartridge valve having an axially movable cartridge piston controlling flow of fluid through a conduit, the cartridge valve having a control chamber for fluid exerting on the cartridge piston a force opposing the force exerted on the cartridge piston by the fluid in the conduit, the control system comprising a control piston aligned with the cartridge piston, a fluid follow-up system operable in response to relative movement between the control piston and the cartridge piston to adjust the pressure in the control chamber so as to cause the cartridge piston to follow-up movement of the control piston, and means for automatically regulat ing the axial setting of the control piston in accord ance with a control signal.
Embodiments of the invention will now be de- 130 scribed, by way of example, with reference to the accompanying drawing, in which:- Figure 1 shows a device for pre-control by the method of pressure reduction, Figure 2 shows a device with a mechanical follow-up system, and Figure 3 shows a device with an electrical position regulation.
In all the Figures, a cartridge valve 1 has a main flow conduit 2 and an outflow 3. In the valve 1 there is an axially movable piston 4which controls flow of fluid from the conduit 2 to the outflow 3. The piston 4 is provided with a duct 4a connecting the conduit 2 to a control chamber 4b at the end of the piston remote from conduit 2 and outflow 3. The duct 4a is formed with a restriction 4c restricting flow of fluid therethrough. Afurther duct 4d in the piston connects the chamber 4b to the outflow 3.
A control valve 8 on the cartridge valve 1 has a piston 7 aligned with the cartridge piston 4. The piston 7 is fitted with a rod 5 which extends into the chamber 4b and co-operates with the adjacent end of duct 4dto form a throttle valve 6. The control piston 7 is loaded by a captive spring 9 which urges the piston 7 in the direction towards the cartridge piston 4 and thereby tends to close the throttle valve 6.
An automatic regulating system 13, 14 or 15 fed with fluid under pressure through line 12 is adapted to supply fluid to opposite sides of the control piston 7 at different pressures so as to exert an axial force on the piston. The adjustment of the pressure difference at the regulating system 13, 14 or 15 is effected through a proportional electromagnet 16. According to the adjustment of the pressure difference at the regulating system by the proportional magnet 16, the pressure at the under side of the piston is increased or reduced according to the desired position of the control piston 7.
The regulating systems consist of a magnetic switch 17 with a piston spool 18 of known construction which, on the one hand is connected through pipelines 19,20 to the compartments above the top 10 of the control piston 7 and below its under side 0 11, and onthe other hand has pipelines 21 tothe reservoir 22 and the line 12 as a connection to the main flow conduit 2. In the embodiment shown in Figure 3, a regulator 23 and a displacement pickup 24 are also provided, the regulator 23 directly influencing the electronic control of the magnetic switch 17.
The regulating system 13 for reducing the pressure works so thatthe differential pressure atthe pre-control piston 7 is compared with the magnet force through the end faces of the piston spool 18. A stable equilibrium results when the force of the spring 9 corresponds to the magnet force, taking into consideration the area relationships.
The main component of the regulating system 13, 14 and 15 is the magnetic switch 17. The mode of operation of this switch 17 is that a spool 18 installed therein blocks all four hydraulic connections 12,19, 20,21 in the neutral position. On deflection of spool 18 to one side, the pressure connection 12 is connected to the upper side 10 of the piston and the 2 GB 2 031 616 A 2 reservoir connection 21 is connected to the under side 11 of the piston. On deflection to the other side, the pressure connection 12 is connected to the under side 11 of the piston and the reservoir connection 21 is connected to the upper side 10 of the piston. The three regulating systems 13,14,15 differ in the manner of the deflection of this spool 18. 1 n the system 13, the proportional magnet 16 first deflects the spool 18 so that oil from the pipe 12 flows to the under side 11 of the piston. The resulting increase in pressure is returned to the end face of the spool at the same time through the pipe 20. The pressure at the upper side 10 of the piston is likewise supplied to the opposite end of the spool through the pipe 19.
This pressure difference at the end faces of the spool produces a force directed counter to the proportional magnet. If the effect of this force is greater than that of the proportional magnet, then it leads to a displacement of the spool 18 in the opposite posi tion. With an equilibrium of forces, the spool 18 returns to the neutral position again. Thus the pressure difference at the piston 7 is proportional to an electrical signal introduced at the proportional magnet 16. The pressure difference at the piston 7 again displaces this towards the captive spring 9. 90 The displacement distance depends on the magni tude of the pressure difference. Thus the displace ment distance of the piston 7 is again proportional to the electric signal introduced into the proportional magnet. System 14 differs from system 13 in that the 95 force of the captive spring which results from displacement of the piston 7 is supplied directly back to the spool 18 and so a direct equalization of force is effected at this spool 18 between the force of the captive spring and the force of the proportional magnet. The regulating process takes place in the same manner as with system 13. System 15 differs from system 14 or 13 in that the position of the piston 7 is measured through a built-in contactless electrical distance indicator 24. An electrical control signal (desired value) is given to the regulator 23 with an integrated amplifier and controls the control valve 8. On a flow through the magnetic switch 17, the control piston 7 is moved. The distance indicator fed through an oscillator measures the position of the main control piston 7 (actual value). This actual value, which is rectified through a demodulator, is supplied to the amplifier which compares it with the desired value. The amplifier controls the magnetic switch 17 until desired value and actual value are equal. Thus the position of the piston 7 is proportion al to the electrical desired value.
To open the cartridge valve the electromagnet 16 is operated to move the piston 7 away from the cartridge valve 4 and thereby open the throttle valve 120 6. Fluid in the chamber 4b then exhausts through the duct 4dto the outflow 3, and the pressure of fluid on the underside of the piston 4 causes the piston 4 to follow up the movement of the piston 7 until the throttle valve 6 is closed. Fluid meanwhile is flowing 125 continuously from the conduit 2 into the chamber 4b at a restricted rate through the duct 4b, and when the piston 4 has moved a sufficient distance to abut against the end of rod 5, thereby closing the throttle valve 6, the pressure in chamber 4b builds up to that 130 necessary to hold the piston 4 at a position close to the end of the rod 5. The cartridge valve may thus be opened to provide any particular cross sectional area of f low therethrough by setting the piston 7 at the appropriate position by the automatic regulating system 13,14 or 15 as explained above.
z
Claims (7)
1. A control system fora cartridge valve having an axially movable cartridge piston controlling flow of fluid through a conduit, the cartridge valve having a control chamberforfluid exerting on the cartridge piston a force opposing the force exerted on the cartridge piston by the fluid in the conduit, the control system comprising a control piston aligned with the cartridge piston, a fluid follow-up system operable in response to relative movement between the control piston and the cartridge piston to adjust the pressure in the control chamber so as to cause the cartridge piston to follow-up movement of the control piston, and means for automatically regulating the axial setting of the control piston in accordance with a control signal.
2. A control system as claimed in claim 1, wherein said fluid follow-up system comprises conduit means for supply of fluid under pressure at a restricted rate from the conduit to the control chamber, a throttle valve on the cartridge piston controlling exhaust of fluid from the control chamber, and a linkage between the control piston and the throttle valve, the linkage being adapted to control the throttle valve in response to relative movement between the control piston and the cartridge piston.
3. Acontroi system as claimed in claim 1 or2, wherein the automatic regulating means for the control piston is operable to control the pressure of fluid acting on opposing ends of the control piston.
4. A control system as claimed in claim 3, wherein the automatic regulating means comprises a spring urging the control piston towards the cartridge piston, a spool movable in opposite directions to direct fluid under pressure to opposite ends respectively of the control piston, the ends of the spool having control surfaces subjected to the same pressures as those acting on opposite ends of the control piston, and electromagnetic means operable to exert an axial force of variable magnitude on the spool, the arrangement being such that in operation the axial position of the control piston is regulated by variation of the force exerted by the electromagnetic means on the spool.
5. A control system as claimed in claim 3, wherein the automatic regulating means comprises a spool movable in opposite directions to directfluid under pressure to opposite ends respectively of the control piston, spring means interposed between the spool and the control piston, and electromagnetic means operable to exert an axial force of variable magnitude on the spool, the arrangement being such that in operation the axial position of the control piston is regulated by variation of the force exerted by the electromagnetic means on the spool.
6. A control system as claimed in claim 5, including means operable to regulate the electro- 3 GB 2 031616 A 3 magnetic means in accordance with the axial setting of the control piston.
7. A control system fora cartridge valve substantialiy as hereinbefore described with reference to any of the Figures of the accompanying drawings.
Printed for Her Majesty’s Stationery Office by Croydon Printing Company limited, Croydon Surrey, 1980. Published bythe Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.
GB7927614A
1978-08-16
1979-08-08
Control system for a valve
Expired
GB2031616B
(en)
Applications Claiming Priority (1)
Application Number
Priority Date
Filing Date
Title
DE19782835771
DE2835771A1
(en)
1978-08-16
1978-08-16
ARRANGEMENT FOR CONTROLLING A CARTRIDGE ELEMENT
Publications (2)
Publication Number
Publication Date
GB2031616A
true
GB2031616A
(en)
1980-04-23
GB2031616B
GB2031616B
(en)
1982-12-15
Family
ID=6047107
Family Applications (1)
Application Number
Title
Priority Date
Filing Date
GB7927614A
Expired
GB2031616B
(en)
1978-08-16
1979-08-08
Control system for a valve
Country Status (5)
Country
Link
US
(1)
US4311296A
(en)
DE
(1)
DE2835771A1
(en)
GB
(1)
GB2031616B
(en)
IT
(1)
IT1212366B
(en)
NL
(1)
NL7905359A
(en)
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US4662600A
(en)
*
1982-09-10
1987-05-05
Hydrolux S.A.R.L.
Adjustable throttle valve
US5178358A
(en)
*
1990-10-31
1993-01-12
Hydrolux S.A.R.L.
Adjustable proportional throttle-valve with feedback
FR2703750A1
(en)
*
1993-04-06
1994-10-14
Oilgear Towler
Hydraulic servo valve, circuit including it and its use in a method for controlling a forging press
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1979-04-07
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Mannesmann Rexroth GmbH, 8770 Lohr
Valve for controlling pressure medium
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1980-10-28
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Robert Bosch Gmbh, 7000 Stuttgart
Load independent control for volumetric flow – has valve piston as volumetric flow sensor with spring and flow pressure control and connection to path detector
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Reinhard Ing.(grad.) 4050 Mönchengladbach Kucharzyk
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Device for actuating a sliding body, in particular the piston-type slide of a directional control valve
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Mannesmann Rexroth GmbH, 8770 Lohr
DEVICE FOR ACTUATING A SLIDING BODY, IN PARTICULAR THE PISTON SLIDER OF A DIRECTIONAL VALVE
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1978
1978-08-16
DE
DE19782835771
patent/DE2835771A1/en
active
Granted
1979
1979-07-09
NL
NL7905359A
patent/NL7905359A/en
not_active
Application Discontinuation
1979-07-18
IT
IT7924463A
patent/IT1212366B/en
active
1979-08-08
GB
GB7927614A
patent/GB2031616B/en
not_active
Expired
1979-08-14
US
US06/066,392
patent/US4311296A/en
not_active
Expired – Lifetime
Cited By (3)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
US4662600A
(en)
*
1982-09-10
1987-05-05
Hydrolux S.A.R.L.
Adjustable throttle valve
US5178358A
(en)
*
1990-10-31
1993-01-12
Hydrolux S.A.R.L.
Adjustable proportional throttle-valve with feedback
FR2703750A1
(en)
*
1993-04-06
1994-10-14
Oilgear Towler
Hydraulic servo valve, circuit including it and its use in a method for controlling a forging press
Also Published As
Publication number
Publication date
IT7924463D0
(en)
1979-07-18
IT1212366B
(en)
1989-11-22
NL7905359A
(en)
1980-02-19
DE2835771A1
(en)
1980-02-28
GB2031616B
(en)
1982-12-15
US4311296A
(en)
1982-01-19
DE2835771C2
(en)
1987-10-22
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Legal Events
Date
Code
Title
Description
1999-09-01
PE20
Patent expired after termination of 20 years
Effective date:
19990807
