GB2099959A

GB2099959A - An electromagnet device and a valve controlled thereby

Info

Publication number: GB2099959A
Application number: GB8212903A
Authority: GB
Original assignee: Sulzer AG; Gebrueder Sulzer AG
Current assignee: Sulzer AG
Priority date: 1981-05-05
Filing date: 1982-05-05
Publication date: 1982-12-15
Also published as: JPS57200777A; IT8220849A0; IT1150543B; GB2099959B; JPH0239675B2; DE3119049A1; DK98982A; DE3119049C2

Abstract

A hydraulic fluid flow control valve comprises a valve stem (11) connected to the armature (15) of an electromagnetic actuator Fig. 1, not shown. The valve stem carries a valve disc 5 having a surface on one side to close an inlet passage 2 and a surface on the other side to close an exhaust passage 4, the diameter of the valve stem being equal to the effective diameters of the said two surfaces. The valve disc extends radially outwards beyond the effective diameters of the said two surfaces to provide axially facing surfaces which cooperate with oppositely facing surfaces on the valve body to afford damping during closing movement of the valve disc. <IMAGE>

Description

SPECIFICATION An electromagnet device and a valve controlled thereby The invention relates to an electromagnet device arranged for the actuation of the movable member of a hydraulic control valve; a valve body being provided which has a hydraulic supply duct, a hydraulic discharge duct and a hydraulic control duct, the movable member being movable in the valve body so as either to connect the supply duct to the control duct and cut off the latter from the discharge duct or to connect the control duct to the discharge duct and cut off the control duct from the supply duct.

In a known device of this kind the electromagnet has a pivoted armature having a plate which extends out of the magnet casing, pivots with the armature and extends between two nozzles. The nozzles are directed towards one another and hydraulic pressure medium flows through them. The moving member of the valve is in operative hydraulic connection with the two nozzles and is in the form of a double-acting spool whose position varies depending on the position of the armature plate between the nozzles. Depending upon the spool position, the control duct communicates either with a supply duct or with the discharge duct, all three ducts being provided in duplicate.Such a device has the disadvantage of being of complicated construction; also, it is unreliable in operation due to the sensitivity of the nozzles to dirt, it is of use only for pressures of up to approximately 200 bar and, since sealing is provided by the spool, there are considerable leakage losses of hydraulic medium It is an object of the invention to provide a device of the kind specified which is of simpler construction than the known device. It is a further object to provide a valve for use at pressures up to 1000 bar, has reduced leakage losses and is more reliable in operation.

Accordingly the present invention provides an electromagnetically actuable hydraulic control valve, comprising a valve body which has a hydraulic supply duct, a hydraulic discharge duct and a hydraulic control duct, a movable valve member which is movable to the valve body so as either to connect the supply duct to the control duct and cut off the latter from the discharge duct orto connect the control duct to the discharge duct and cut off the control duct from the supply duct, in which the valve member is a poppet valve having a stem which extends in the direction of movement of the armature of an electromagnet actuator and is connected thereto for direct transmission of armature movemenu to the valve member, the valve member has two annular sealing surfaces which are disposed opposite to one anotherto cooperate selectively with a respective one of two annular seat surfaces disposed in the valve body, one on either side of the poppet valve, the valve stem is guided and sealed in the valve body, the diameter of the valve stem is equal to the inner diameter of the seat surfaces in the valve body, and the valve has a disc-like extension which extends radially outwards beyond the sealing surfaces and whose radial boundary surfaces cooperate with valve-body surfaces parallel to them to define gaps which are filled with fluid in use damping movement of the poppet valve.

The direct connection between the magnet armature and the moving member of the valve helps to reduce the cost of the device considerably and makes for a compact construction. Also, nozzles which are sensitive to dirt are obviated. The sealingtightness between the various ducts is better with the poppet valve than in the prior device, so that there is no appreciable leakage loss. Since the valve stem diameter is equal to the inner diameter of the seat surfaces in the body, there is a substantial pressure equalisation at the poppet valve in the suppy duct. Since the valve has the disc-like extension between the sealing surfaces, movement of the valve head is damped shortly before it strikes a seat surface in the valve body; consequently, the annular seat and sealing surfaces can be of very reduced effective width.

In order to promote a fuller understanding of the above and other aspects of the present invention, an embodiment will now be described, by way of exam p!e only, with reference to the accompanying drawings in which: Figure 1 is an axial section through a valve device; Figure 2 is a view to an enlarged scale of the part within broken lines in Figure 1; Figure 3 is a partial view similarto Figure 2 of an alternative embodiment, and Figure 4 is a section on the line IV-IV of Figure 3.

Figure 1 shows a valve body 1 which has a supply duct for a pressure medium which is at a high pressure of, 1000 bar, supplied by a source (not shown).

The valve body 1 also has a control duct3 leading to means (not shown) controlled by pressure medium in the duct 3, such means being, for example, a fuel injector of a diesel engine. The two ducts 2,3 can communicate with one another by way of an aperture controlled by a poppet valve 5 disposed for movement in the valve body 1. A discharge duct4 is disposed, below the poppet valve 5 in Figure 1, in a spiggot 6 introduced into the valve body 1. The duct 4 enables pressure medium returning through the control duct 3 to go to a sump or the like (not shown). A duct 4' branches off the duct 4, and extends to the top part of the valve body 1 and serves as a discharge for leaked fluid.

Disposed in the body 1 between the ducts 2 and 3 is an annular valve seat surface 7 which so cooperate with an annular sealing surface 8 of the poppet valve 5, that the effective seat width is determined by the diameter D of the bore 2' and outer diameter D' of the seat surface part 8 of the poppet valve 5 (Figure 2). A seat surface 9 corresponding to the seat surface 7 is provided in the top annular end face of the spiggot 6. The seat surface 7 extends around the discharge duct4 and cooperates with a second annularsealing surface 10 of the poppet valve 5. The sealing surface 10 is similar to and disposed opposite to the sealing surface 8. This construction enables a very narrow seat width to be used without constructional difficulties.The seat width is determined by the surface relationship: F'-F When p and F' are as indicated in Figure 2, and is preferably at most 5% of F. The poppet valve 5 extends radially beyond the sealing surfaces 8, 10 being in the form of a disc40 whose top boundary surface 37 and bottom boundary surface 38, each extend perpendicularly to the axis of the valve stem 11 and are set back slightly from the surfaces 8, 10 respectively.Near the disc 40, those surfaces of the body 1 or the spiggot 6 into which the seat surfaces 7,9 merge radially, extend parallel to the boundary surfaces 37,38 of the disc 40, so that with the valve 5 in a closed position a narrow gap remains between either the surface 37 orthe surface 38 of the disc40 and the adjacent surface of the body 1 or the spiggot 6.

The function of this gap is to damp the movement of the valve 5 as it approaches either of its two closed positions. One of the advantages of this kind of damping isthatthe beginning of damping is unaffected by differences due to thermal expansion.

The valve 5 has at the top in Figure 1 a cylindrical cross-section stem 11. The stem has a portion 11' of reduced cylindrical cross-section near the supply duct 2. The stem 11 is guided and sealed by the cylindrical part 11 having a close fit in a bore 12 in the body 1. The diameter of the cylindrical portion of stem 11 is equal to the inner diameter of the seat surfaces 7,9. At itstopthe stem merges into a rod 13 extending through an electromagnet device 14 which is also housed in the valve body 1.

The electromagnet device 14 comprises an armature in the form ofathin-walled obtuse-angled hol low cone 15 and a two-piece electro-magnet body 16, 16' whose conical surfaces adjacent the cone bound the air gap and comprise the energised con ductors. The construction of such an electromagnet has been described in greater detail in the Applic ants' co-pending Application No. (Reference P5604).

The armature 15 is connected to the rod 13 of the valve 5 by means of sleeve 17 which extends around the rod 13, is thickened like a flange at its bottom end in Figure 1 and bears by way of its thickened end on an annular disc 18 bearing on a pair of cup springs 19. The cup springs bear by way of a ring 20 on the valve stem 11.At its top end in Figure 1 the sleeve 17 thickens inwardly and bears by way of this end on a pair of cup springs 21 bearing by way of an annular disc 22 on a two-piece ring 23 engaging in a conical groove in the top end of the rod 13. When assembled the ring 23 is located radially by a projecting rim of the disc 22. Two sleeves or the like 24, 25 are disposed axially one above another on the sleeve 17 and these clamp the armature 15 between them.

Clamped between the bottom end of member 24 and the flange-like end of sleeve 17 is a centering spider 26 having a number of curved radial arms whose outer ends are clamped between a magnet body 16 and the valve body 1. A similar centering spider 27 is clamped between the top end of the sleeve member 25 and a ring 28 screwed to the top end of the sleeve 17, on the one hand, and the magnet body 16' and a cup spring 29 on the other hand. The connection described enables the movement of the armature 15 to be transmitted to the poppet valve 5 directly; the cup spring pairs 19, 21 permit small relative axial movements between the poppet valve 5 and the armature 15 since it may happen that the poppet valve 5 is already seating but the armature has not reached its stop.The inner stops or abutments for the armature are adjusted relatively to the seating positions of the poppet valve 5 in the body 1 by adjustment of the thickness of a ring 20' in cooperation with the preloading of the cup spring 29 by the cover 30. Also, there is considerable radial clearance between the rod 13 and the sleeve 17 and such clearance enables free radial adjustment of the valve axis and magnet axis across the discs 18,22 respectively.

In operation, when pressure medium is required to flow through the control duct3 to the means to be controlled, the magnet is energised to pull the armature 15 downwards in Figure 1 sothatthe valve 5 has its sealing surface 10 pressed into engagement with the seat surface 9. High-pressure medium can then discharge from the supply duct 2 to the control duct 3. To interrupt the supply of pressure medium, the magnet is energised to move the armature 15 into the top position, shown in Figure 1,the poppet valve 5 also rising so that its sealing surface 8 is engaged with the seat surface 7 and communication is opened between the control duct 3 and the discharge duct 4.Pressure medium now flows from the control duct 3 through the discharge duct 4. Since the movements alternate very rapidly, dynamic stressing of all the surfaces 7,8,9 and 10 isconsid- erable and these items should therefore be made of a high-strength material, for example, casehardened steel, which permits a high specific surface pressure. The damping facility hereinbefore described, in the form of the disc 40 on the poppet valve 5, provides simple, reliable and cheap damping as since the valve moves towards a seat surface the hydraulic pressure medium in the gap adjacent such surface tends to resist displacement.Since the annular seat surfaces 7, 9 are very narrow and their inner diameter corresponds to the diamter of the cylindrical part of the stem 11, hydraulic forces in the duct 2 acting on the poppet valve 5 are substantially compensated for.

In the embodiment shown in Figures 3 and 4, the poppet valve has, on the side distant from the stem portion 11', guide pin 39which extends into the discharge duct4 and which is of uniform crosssection. The cross-section of the pin 39 is such that the entire flow cross-section between it and the surrounding duct 4 is equal to the flow cross-section of the supply duct 2 near the valve stem portion 11'.

This feature assists satisfactory guidance of the poppet valve 5 and satisfactory equalisation of pressure losses on the inflow and outflow side.

Instead of the sealing and seat surfaces 7,8,9 and 10 being flat as described, they can be conical. To provide sealing and seat surfaces able to withstand high surface pressures, the surfaces can have hard metal armouring.

The electromagnet connected to the poppet valve 15 can be magnetically single-acting with spring return instead of magnetically double-acting. A single-acting magnet for very rapid movements has been disclosed in the Applicants' co-pending patent application No. (Reference (P. 5603)).

Claims

1. An electromagnetically actuable hydraulic control valve, comprising a valve body which has a hydraulic supply duct, a hydraulic discharge duct and a hydraulic control duct, a movable valve member which is movable in the valve body so as either to connect the supply duct to the control duct and cut off the latter from the discharge duct orto connect the control duct to the discharge duct and cut off the control duct from the supply duct, in which the valve member is a poppet valve having a stem which extends in the direction of movement of the armature of an electromagnet actuator and is connected thereto for direct transmission of armature movement to the valve member, the valve member has two annular sealing surfaces which are disposed opposite to one another to cooperate selectively with a respective one of two annular seat surfaces disposed in the valve body one on either side of the poppet valve, the valve stem is guided and sealed in the valve body, the diameter of the valve stem is equal to the inner diameter of the seat surface of the valve body, and the valve has a disclike extension which extends radially outwards beyond the sealing surfaces and whose radial boundary surfaces cooperate with valve-body surfaces parallel to them to define gaps which are filled with fluid in use damping movement of the poppet valve.

2. A valve as claimed in Claim 1 in which the valve-body seat surfaces and the poppet valve sealing surfaces are made of high-strength material.

3. A valve as claimed in Claim 1 or 2, in which resilient means is provided in the connection between the valve stem and the armature.

4. Avalve as claimed in Claim 1,2 or3 in which the connection between the valve stem and the armature is such that the stem can move radially relative to the armature.

5. A valve as claimed in any one of Claims 1 to 4 in which the poppet valve has, on the side distant from its stem, a guide pin which extends into the hydraulic discharge duct and which leaves free between itself and the discharge duct a flow crosssection equal to the flow cross-section of the supply duct near the valve stem.

6. A valve as claimed in any one of Claims 1 to 5 in which the electromagnet actuator is mounted in the valve body.

7. A valve as claimed in any one of Claims 1 to 6 in which the position of the electromagnet device is adjustable axially relative to the valve body.

8. An electromagnetically actuable hydraulic control valve substantially as herein described with reference to the accompanying drawings.