GB2133583A

GB2133583A - Electrically actuated hydraulic regulating valve

Info

Publication number: GB2133583A
Application number: GB08334049A
Authority: GB
Inventors: Adam Dittner; Karl Prenzel
Original assignee: FAG Kugelfischer Georg Schaefer KGaA; Kugelfischer Georg Schaefer and Co
Current assignee: IHO Holding GmbH and Co KG
Priority date: 1982-12-24
Filing date: 1983-12-21
Publication date: 1984-07-25
Also published as: DE3247953C2; GB2133583B; DE3247953A1; FR2538495A1; FR2538495B1; GB8334049D0

Abstract

A moving-coil motor (5) or a motor comprising a disc rotor is connected to a motion-converting gear (27, 28, 29) by way of a permanent-magnet across-the-wall clutch (22, 23). This converts the rotary movement of the motor (5) into a translatory movement of an auxiliary piston (30). The latter acts as a hydraulic actuating element for a cylindrical follower piston (38), which forms the valve slide. The permanent-magnet across-the-wall clutch is contained in a regulating circuit, which comprises the moving-coil motor (5) and a means for generating a signal representing the position of the valve slide, said means being provided on the auxiliary piston (30). <IMAGE>

Description

SPECIFICATION Electrically actuated hydraulic regulating valve -This invention relates to an electrically actuated hyd raulic regulating valve with a drive in the form of a motor having a disc rotor or moving coil, which motor, by way of a gear which converts rotary movement into translatory movement, is in driving connection with a cylindrical valve slide, the position of which is detected by means for generating a signal representing position which is applied as the actual value to a regulating amplifier, to another input of which a valve position required value can be applied, and the output of which acts on the motor.

Such a valve with a motor having a disc rotor is described in DE-PS 24 56 677, and a valve of this kind having a moving coil motor is described in DE-PS 26 02 375 in the name ofthe present Applicants. Both of these valves offer the advantages of a high setting speed and good control accuracy, while being of rela tively simple construction. They can therefore be used in all cases in which these properties are required and when the throughput volume is not too great. Because the cylindrical valve slide is driven directly through the movement-conversion gear, there is an upper limit to the size of this valve slide.

An aim of the present invention is to provide a valve ofthe construction setforth in the opening paragraph of this Specification, which while permitting a rela tively high throughput volume, is also distinguished by a high setting speed, good control precision and the absence of dynamically loaded sealing means.

Accordingly, in a valve according to the present invention, a permanent-magnet clutch is arranged between the drive and the gear with its primary part positioned outside the valve housing and its secon dary part inside the valve housing which at this point comprises a non-magnetic partition, in which the output side of the gear is in driving connection with a longitudinally displaceable auxiliary piston which is centrally arranged in the valve slide, the latter being constructed as a hydraulically actuated follow-up pis ton controlled by the auxiliary piston, and in which the means for generating a signal representing posi tion is actuated by the auxiliary piston.

An example of a valve made in accordance with the present invention is illustrated in the accompanying drawing, in which: Figure 1 shows an axial sectional view of the valve; and Figure 2 illustrates, on a larger scale, a detail from Figure 1.

Figure 1 shows a valve housing 1 and a housing 2 for the drive. The two housings are interconnected, and inserted between them is a non-magnetic parti tion 3, which has a flat-bottomed depression 4 at its middle. The moving coil 5 of the moving-coil motor here used is accommodated in the housing 2. The moving coil 5 surrounds a stationary annular short circuit plate or core 6 of soft iron. Arranged immove ably on each side of this plate are two pairs of sector shaped permanent magnets 7 and 8, 9 and 10, the magnets of each pair being disposed diametrally opposite each other. Bonded to the rear face of each pair of magnets is a common annular short-circuit plate 11 or 12 of soft iron.

The ends of the moving coil are attached to helical springs 13 and 14. The latter are connected to the output of a regulating amplifier 16 through a lead 15.

The moving coil 5 is secured in a bifurcated element 17. The latter is connected to a spindle 19 by a screw and taper connection 18. The spindle is mounted in ball bearings 20 and 21. At its end, this spindle carries the primary part 22 of a permanent-magnet clutch.

The associated secondary part 23 of the clutch is located in the depression 4 on the other side of the non-magnetic partition 3.

The secondary part 23 of this clutch is secured on a spindle 24 which is mounted in ball bearings 25 and 26 which are arranged inthe housing 1. A ball bearing 27 is secured off-centre on the other end of the spindle 24. This bearing is in operative connection with two driving discs 28 and 29. The latter are secured on an auxiliary piston 30. As indicated by the arrow 31, the auxiliary piston 30 is moved to the right or the left when the spindle 24 rotates.

Achamber32 surrounds this auxiliary piston 30. An annular ferritic body 33 is secured to the right-hand end of the auxiliary piston 30. This body, together with adjacent coils 34 and 35, forms a distancemeasuring system. Forthis purpose, the said coils are connected in the known mannerto a bridge circuit 36, which in turn is connected to the actual-value input (+) of the regulating amplifier 16. The required-value input (-) of the regulating amplifier leads to the terminal 37. This serves to supply a required value for the valve setting.

A cylindrical valve slide 38 co-operates with connecting orifices, i.e. annular chambers 39, 40, 41, 42 and 43. Of these, the connecting orifice 41 provides a connection with a pressure-medium source, for example a hydraulic pump, whereas the orifices 39 and 43 communicate with an oil-suppiy container.

Depending upon the displacement of the valve slide 38, a connection is established between the orifice 41 and one of the orifices 40 and 42. This system is known per se and is not therefore described here in detail.

Secured to the auxiliary piston 30 are two closure cones 44 and 45. These are arranged at a slight distance from closure edges in blind-end holes 46 and 47 which are formed in the end-faces of the valve slide 38. Shaped sealing means are fitted on the auxiliary piston 30 between the closure cones 44 and 45.

Transverse bores 50 and 51 are formed in the valve slide 38 in the manner illustrated, and inclined ducts 52 and 53 are also formed therein.

In the zone of the annular chamber 41, annular cams 54 and 55 (shown in Figure 2) are secured to the auxiliary piston 30. Together with the surrounding housing parts, these cams form throttle gaps 56 and 57. There are also main gaps 58 and 59 around the auxiliary piston 30. Thus, the duct 53 establishes a connection between the annular gap 59 and the chamber 32, whereas the duct 52 establishes a connection between the annular chamber 58 and a chamber 60, which extends leftwards as far as a closure screw-cap 61. Provided at the left-hand end of the auxiliary piston 30 is a middle-position spring 62. This biases the auxiliary piston 30 to hold it in the rest position in the illustrated neutral situation.

The valve operates as follows: in the illustrated rest position, in which current does not flow through the moving coil 5, hydraulic oil flows under pressure from the annular duct 41 towards both sides and into the annular chambers 58 and 59 through the throttle gaps 56 and 57 and, from these chambers, it passes through the ducts 52 and 53 into the chambers 60 and 32. Since, as mentioned above, the closure cones 44 and 45 are each slightly spaced from their associated closure edges, the hydraulic oil can now flow from the chambers 60 and 32 past the closure cones by way of the ducts 50 and 51 and intotheconnecting openings 39 and 43, and therefore into the oil-supply container.

Because of the symmetrical arrangement of these paths at both sides of the annular duct 41, the valve slide 36 is hydraulically centred in relation to the closure cones 44 and 45.

If a current is now applied to the moving coil 5so as to move the auxiliary piston 30 to the left, this causes the closure cone 44 to be pressed on to its closure edge. Furthermore, with reference to Figure 2, the annular cams 54 and 55 are moved to the left. The resistance to flow in the throttle gap 56 thus becomes greater than that in the throttle gap 57. As a result of this, hydraulic oil is abletoflow in increased amounts into the chamber 32 by way ofthethrottle gap 57, the annular duct 59 and the duct 53. Since, as already stated, the closure member 44 now bears firmly against its closure edge, this hydraulic oil is able to act on the entire right-hand end-face ofthe valve slide 38.

Thelattertherefore movestotheleftinthe mannerof a follower piston or servo-piston, and this continues until a new hydraulic centring position of the valve slide 38 has been established between the closure cones 44 and 45. The means 33,34 and 35 for generating a signal representing the position of the valve slide indicates whether the displacement distance of the auxiliary piston 70 corresponds to the required value supplied by way of the terminal 37.For this purpose a complete regulating circuit (not shown) formed which extends from the output ofthe regulating amplifier 16 and passes through the moving coil 5, the magnetic clutch 22, 23, and gear 27,28, 29, the signal-generating means 33, 34 and 35, the bridge circuit 36 as well as the actual-valve input of the regulating amplifier 16.

The angled arrangement of the valve housing 1 and the drive housing 2 illustrated in the example is not the only one possible. The drive housing may also be arranged as an axial extension of the auxiliary piston 30. The motion-converting drive can then be constructed, for example, in the manner specified in the initially mentioned patent specifications in the name of the present Applicants.

As can be seen from the example described, the high displacement speed and the great operating precision of the known arrangements can still be maintained by means of the moving coil motor drive.

Because ofthe indirect driving of the valve slide 38 by way of the auxiliary piston 30 actuated by the moving-coil motor, there is practically no upper limit to the throughputvolume. Finally, because of the use of the permanent-magnet across-the-wall clutch 22, 23, it is possible to provide a construction wherein all ofthe elements participating inthefunctioning ofthe valve, such as, for example, the valve slide 38, can operate without the provision of dynamically loaded sealing means. This contributes considerably towards obtaining a high displacement speed and control precision in view of the great throughput volume. The fact that the signal-generating means 33 is secured to the auxiliary piston 30 and not to the valve slide 38 offers an advantage of increased stability as regards regulating technique.

Claims

1. An electrically actuated hydraulic regulating valve with a drive in the form of a motor having a disc rotor or moving coil, which motor, by way of a gear which converts rotary movement into translatory movement, is in driving connection with a cylindrical valve slide, the position of which is detected by means for generating a signal representing position which is applied as the actual value to a regulating amplifier,to another input of which a valve position required value can be applied, and the output of which acts on the motor, in which a permanentmagnet clutch is arranged between the drive and the gear with its primary part positioned outside the valve housing and its secondary part inside the valve housing which at this point comprises a nonmagnetic partition, in which the output side of the gear is in driving connection with a longitudinally displaceable auxiliary piston which is centrally arranged in the valve slide, the latter being constructed as a hydraulically actuated follow-up piston controlled by the auxiliary piston, and in which the means for generating a signal representing position is actuated by the auxiliary piston.

2. An electrically actuated hydraulic regulating valve substantially as described herein with reference to the accompanying drawing.