GB1568950A - Servo pilot valve - Google Patents

Description

PATENT SPECIFICATION

( 21) Application No 7233/79 ( 22) Filed 3 May 197 0 ( 62) Divided out of No 1568949 mf) ( 31) Convention Application Nos.

796650 ( 32) Filed 13 of 797 162 16 0 ( 33) United States of America (US) ( 44) Complete Specification published 11 June 1980 ( 51) INT CL 3 F 15 B 9/07 HOIF 7/14 ( 52) Index at acceptance G 3 P 11 12 A 16 EX 18 21 24 KX X Hi P 1 E 2 B 2 J ( 72) Inventors DOUGLAS W AMOS DWAWNE R ELMBEG ( 11) May 1977 May 1977 in ( 54) SERVO PILOT VALVE ( 71) We, HONEYWELL INC, a Corporation organised and existing under the laws of the State of Delaware, United States of America, Honeywell Plaza, Minneapolis, Minnesota 55408, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed to be particularly described in and by the following statement:-

This invention relates to pilot valves suitable for controlling servo valves.

According to the invention, there is provided a magnetically operated pilot valve comprising a generally U-shaped frame; a first rare earth-cobalt magnet attached to one arm of the frame; a second rare earthcobalt magnet attached to the other arm of the frame; an armature attached at one end to the bight of the frame, the other end extending between the magnets; a coil means wound round the armature; and a valve attached to the armature for controlling the flow of fluid from an inlet to an outlet port.

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which:Figure 1 is a cross-sectional view of the pilot valve according to the present invention; Figure 2 is a partial cross-sectional front view of the valve shown in Figure 1 but without the cover; Figure 3 shows the surface topography of the surface of the receiver plates which face the splitter plate of the receiver shown in Figure 1; Figure 4 is a front view of the splitter plate; Figure 5 is a cross-sectional view of Figure 1 taken along line A-A; Figure 6 is a fragmentary view of the jet pipe, splitter plate, and actuating arm assembly of the valve shown in Figure 1; Figure 7 shows the jet pipe used in the pilot stage valves; Figure 8 is an end view of the jet pipe; 50 and Figure 9 shows the frame and armature for supporting the coil of the magnetic operator of the valve in Figure 1; and, Figure 10 shows an alternative construc 55 tion for the pilot valve according to the invention The pilot valve 10 shown in Figure 1 has cover portion 11 secured by appropriate screws (not shown) to base section 12 and 60 has sealing gasket 23 therebetween Inlet port 14 communicates with chamber 15 through channel or aperture 16 Chamber also communicates with threaded aperture 17 which has sealing plug 18 therein 65 Extending through base 12 and suitably secured thereto, as by an adhesive, is hollow jet pipe 19 which communicates with the chamber 15 The other end of the jet pipe 19 is moved vertically within recess 70 of base 12 by actuating arm or push rod 21 As best shown in Figure 6, jet pipe 19, during assembly, is pushed through aperture 23 in flattened section 22 of push rod 21 until groove 24 (Figure 7) in jet pipe 75 19 snaps into aperture 23 Flattened section 22 and aperture 23 act as a clip to secure jet pipe 19 to actuating arm 21.

Fluid is supplied to chamber 15 under pressure from a source connected to port 80 14 and travels from chamber 15 through jet pipe 19 and out of jet pipe 19 to receiver section 30 The receiver section comprises first and second receiver plates 31 and 32 with a splitter plate 33 sandwiched 85 therebetween Receiver plate 31 is shown in more detail in Figures 3 and 4 and comprises a plate having groove 34 cut in the surface of receiver plate 31 facing splitter plate 33 The grooves extends from notch 90 1 568 950 1 568 950 at the edge of the receiver plate and extends to aperture 36 through the receiver plate Receiver plate 32 is identical to receiver plate 31 and the two receiver plates S are positioned with respective grooves 34 facing one another separated by splitter plate 33 and with their respective notches directed towards the end of jet pipe 19 for receiving fluid therefrom The receiver plates have an additional aperture extending therethrough at 37.

As better shown in Figure 5, aperture 36 of receiver plate 32 overlies aperture 37 of receiver plate 31 Also, aperture 37 of receiver plate 32 overlies aperture 36 of receiver plate 31 With this construction, groove 34 of receiver plate 31 extends from its notch 35 to its aperture 36 whereas groove 34 of receiver plate 32 extends from its notch 35 to its aperture 36 Aperture 36 of receiver plate 32 communicates with outlet port 40 through aperture 41 in splitter 33, aperture 37 in receiver plate 31 and channel 42 in base 12 Likewise, aperture 36 in receiving plate 31 communicates with corresponding outlet port 43 through channel 44 in base 12 It is to be noted that splitter plate 33 has no corresponding aperture to communicate aperture 37 of receiver plate 32 with aperture 36 of receiver plate 31 since groove 34 of receiver plate 31 communicates with port 43 through aperture 36 of receiver plate 31 and channel 44 without going through the splitter plate Cover and sealing plate 45 is secured over the sandwiched construction of receiver plates 31 and 32 and splitter plate 33 by suitable screws 46, 47 and 48 which extends through suitable holes in cover plate 45, receiver plate 32, splitter plate 33 and receiver plate 31 and finally into base 12.

Fluid issuing from jet pipe 19 impinges onto notches 35 of receiving plates 31 and 32 and will travel along corresponding grooves 34 and then down respective channels 42 and 44 to respective ports 40 and 43 If the jet tube 19 is midway between notches 35 of receiver plates 31 and 32, an equal amount of fluid will be received at outlet ports 40 and 43 If the jet tube 19 is moved in an upward direction, outlet port 40 will receive a greater proportion of the fluid and, if jet tube 19 is moved in a downward direction from its midposition, outlet port 43 will receive a greater proportion of the fluid Jet pipe 19 is moved vertically with respect to the receiving assembly 30 by the push rod or actuating arm 21 Actuating arm 21 is driven by a control mechanism or magnetic operator 50 shown in Figures 1 and 2.

Assembly 50 comprises generally Ushaped frame 51 of a low hysteresis magnetic flux conducting material The frame is shown in more detail in Figure 9 and has appropriate slots 52 and 53 for receiving screw 54, and slot 55 and a corresponding slot below 55 for receiving a second screw corresponding to screw 54 70 Frame 51 has first arm 56 and second arm 57 connected together at their ends by cross-piece of bight 58 In the preferred embodiment, frame 51 is a unitary piece which is stamped and bent in the generally 75 U-shaped fashion as shown Arm 56 has recess 60 therein and arm 57 has corresponding recess 61 Rare earth-cobalt magnet 62 having a first polarity is set into recess 60 and will be held thereto by 80 its magnetic attraction for frame 51.

Second rare earth-cobalt magnet 63 of opposite polarity is inserted into recess 61 and will be held thereto by its magnetic attraction for frame 51 Rare earth such as 85 samarium, praseodymium and misch-metal may be alloyed with cobalt to provide the magnets with different magnetic properties.

Pole pieces 64 and 65 are respectively associated with and attached to magnets 90 62 and 63 by suitable means such as an adhesive The magnetic circuit structure is completed by armature 70 which is suitably attached to cross-piece 58 of frame 51 As shown, armature 70 is welded to bracket 71 95 which is in turn welded to cross-piece 58 of frame 51.

Bobbin 72 is inserted over armature 70 and has corresponding U-shaped ends 74 and 75 aligned with the corresponding 100 slots 52, 53 and 55 of frame 51 for receiving corresponding screws 54 Screws 54 thus secure control mechanism or magnetic operator 50 to base 12 Finally, winding 76 is wound around 72 and is suitably 105 supplied with a pair of terminals (not shown) for receiving an input signal from an external source Depending upon the polarity of the signal applied to winding 76, the armature will be either driven away 110 from pole piece 64 to pole piece 65 or driven away from pole pieces 65 to pole piece 64.

Armature 70 has a clip 80 as shown for releasably securing armature 70 to push 115 rod 21 Push rod 21 is inserted through slot 81 of clip 80 into the aperture 82 therein Thereafter, screw 83 is inserted between the front portion of clip 80 and push rod 21 and a nut 84 is secured over 120 the screw 83 to pinch clip 80 against push rod 21 Thus, push rod 21 cannot slide with respect to armature 70 but is instead, driven by armature 70.

The upper end of push rod 21 has bulge 125 91 for butting against washer 90 which in turn butts against spring 92 The spring 92 pushes against washer 93 which is suitably attached to one end of screw 94.

Screw 94 extends through press nut 95 130 1 568 950 which is pressed through aperture 96 of frame 51 Screw 94 may be driven by a suitable wrench, such as a hexagonal key wrench, for biasing push rod 21 and armature 70 in a vertical direction.

At the lower end of push rod 21 is bulge which butts against washer 101 which in turn butts against feedback spring 102.

Feedback button 103 may be connected to a suitable feedback mechanism on the servo valve which is being controlled by pilot valve 10 for providing a feedback function Biasing spring 92 and adjustment screw 94 are utilized to center jet tube 19 with respect to splitter plate 33 when no input is supplied to coil 76 Push rod 21 extends through a suitable slot 105 in frame 51.

In operation, with no input signal applied to coil 76, the fluid issuing from jet pipe 19 will be divided by splitter plate 33 to both receiving plates 31 and 32 so that outlet ports 40 and 43 receive equal amounts of fluid As an input signal is applied to coil 76 of one polarity, armature will be driven up pulling jet pipe 19 up to increase the flow to outlet port 40 and decrease the flow to outlet port 43.

If an opposite polarity signal is supplied to the coil 76, armature 70 is driven downward to correspondingly drive jet pipe 19 down to increase the fluid flow to outlet port 43 and decrease the fluid flow to outlet port 40.

Splitter plate 33 has generally U-shaped retaining arm 110 extending from one side thereof One leg of U-shaped arm 110 is shorter than its opposite leg and terminates in clip 111 Clip 111 is formed of a Vshaped notch 112 with an aperture 113 at the apex of the V During assembly, clip 111 is bent down until jet pipe 19 snaps into aperture 113 In this manner, jet pipe 19 is retained against lateral motion along the edge of splitter plate 33 facing jet pipe 19 and is allowed only vertical motion across splitter plate 33 and receiver plates 31 and 32.

An alternative pilot valve 200 is shown in Figure 10, which is basically the same type of construction as that shown in Figures 1 to 9 but with the jet pipe running through the armature instead of being connected to the armature by pusher 21.

Specifically, pilot stage valve 200 has a cover 201 which fits over base section 202 with gasket 203 for sealing Magnetic arrangement 204 is essentially the same as shown in Figures 1 to 9 but, in Figure 10, is shown in partial cross section Specifically, magnetic structure 204 comprises a generally U-shaped frame 205 having a bobbin 206 and winding 207 wound therearound Through a center hole in bobbin 206 is mounted armature 208 attached to frame 205 by bracket 209 Clip 210 is inserted over the end of armature 208 and jet pipe 211 extends through the armature 208 and through base section 202 to chamber 212 Chamber 212 is connected to input 70 port 213 by channel 214 Plug 215 seals chamber 212 The magnetic structure 204 also comprises magnets 216 and 217 with pole pieces 218 and 219 Armature 208 is biased by springs 220 and 221 Spring 220 75 is adjustable by screw 222 fitted through nut 223 Spring 220 is centered about plate 224 and projection 225 Spring 221 is centered by plate 226 and projection 227.

Hydraulic fluid or other fluid is supplied 80 through port 213 to chamber 212 and from there flows through jet pipe 211 and out of jet pipe 211 to receiving section 230.

Receiver section 230 comprises receiver plates 231 and 232 with a splitter plate 233 85 of the same construction as shown in Figure 1 to 9 Splitter plate 233 terminates in a clip 234 which secures jet pipe 211 against transverse movement Receiving section 230 has a cover plate 235 and 90 the entire assembly is fastened to base 202 by screw 236 Channel 237 communicates one of the receiving plates 231 or 232 to an outlet port 238 The other receiving plate is connected in the manner shown in 95 Figures 1 to 9 to a second output port.

A feedback arrangement may comprise spring 240 hooked over a groove in jet pipe 211, such as groove 24 in jet pipe 19 of Figure 7, and is attached at its other end 100 to a crank arm 241.

As can be seen, the arrangement shown in Figure 10 has the benefit that the jet pipe is controlled directly by the armature without any intervening mechanical link 105 age.

Reference is directed to application No.

17346/78 (Serial No 1568949) which contains claims directed to other features of the above described pilot valve 110

Claims (6)

WHAT WE CLAIM IS: -

1 A magnetically operated pilot valve comprising a generally U-shaped frame; a first rare earth-cobalt magnet attached to one arm of the frame; a second rare earth 115 cobalt magnet attached to the other arm of the frame; an armature attached at one end to the bight of the frame, the other end extending between the magnets; a coil means wound round the armature; and a 120 valve attached to the armature for controlling the flow of fluid from an inlet to an outlet port.

2 The pilot valve of claim 1, wherein the coil means comprises a bobbin sur 125 round the armature and a coil wound round the bobbins.

3 The pilot valve of claim 2, wherein the bobbin and said arms have aligned slots for receiving a fixing member to secure 130 1 568 950 the frame and bobbin to a body of said valve.

4 The pilot valve of claim 1, 2 or 3, wherein the valve is actuated via a pushrod secured to the armature by means of a releasable connection.

The pilot valve of claim 4, including a biasing spring acting between the frame and push rod to bias the push rod.

6 The pilot valve of any one of the 10 preceding claims, including a jet pipe connected to the inlet port, and a receiving means connected to the outlet port and receiving a jet of fluid from the jet pipe.

JOHN RIDDLE, Agent.

Printed for Her Majesty's Stationery Office by The Tweeddale Press Ltd, Berwick-upon-Tweed, 1980.

Published at the Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.