GB1578915A - Electromagnetic pressure regulating valve - Google Patents

Description

(54) AN ELECTROMAGNETIC PRESSURE REGULATING VALVE (71) We, ROBERT BOSCH GmbH., a German company of Postfach 50, 7000 Stuttgart 1, Germany., 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 followin statement: This invention relates to an electromagnetic pressure regulating valve.

German Gebrauchsmuster No. 72 02 049 discloses a pressure regulating valve which comprises a solid control rod having an armature connected to one of its ends, the other of its ends engaging a differential piston. In this arrangement, the valve unit and the magnet unit form two essentially separate constructional units. Thus, the pressure regulating valve is relatively large and of expensive construction. Furthermore, when the magnet is operated, magnetic flux passes through the control rod so that there is a danger that magnetic jamming will occur.

German Auslegeschrift No. 2 019 345 discloses a pressure regulating valve in which a rod serves both as a valve member and as an armature. Apart from a connection for the fluid to be regulated this valve has only one further connection to discharge. Thus, when it is in operation, relatively large energy losses occur involving the use of considerable electrical energy to provide a usable pressure regulation. Once again, magnetic jamming can also occur due to magnetic flux passing through the valve member. Moreover, since the magnet is exposed to the full pressure of the fluid to be regulated, metallic products resulting from wear on the moving parts can enter the magnet chamber where they settle and lead to breakdown of the valve.

An electromagnetic pressure regulating valve in accordance with the invention comprises a housing, an electromagnet arranged in the housing, a control rod mounted at each of its ends for axial movement in the housing and an armature of the electromagnet fixed to the control rod, one end of the control rod being formed as a hollow slide valve member mounted in a non-magnetic slide bearing, the valve member and the slide bearing forming a slide valve controlling communication between respective pressure fluid supply and discharge ports and a control port, the control port being arranged to be connected to a source of fluid under pressure to be regulated and being in permanent communication with an area on the slide valve member responsive to axial pressure in opposition to the force applied to the control rod by the electromagnet, so that the pressure of the source of fluid to be regulated can be controlled by the control valve in accordance with the force provided by the electromagnet.

In such a pressure regulating valve, magnetic jamming of the control rod is largely prevented by mounting the slide valve member in a non-magnetic slide bearing. Furthermore, the danger of magnetic jamming can be virtually obviated by a magnetic flux conducting plate shielding the end of the control rod opposite to that of the valve member.

In a preferred form of regulating valve, the slide valve is arranged in a valve housing which is integral with the electromagnet housing, for example by being made to plug-in to the electromagnet housing. This leads to a simple and compact construction.

By arranging the discharge port remote from the control port, the magnet is only exposed to the discharge pressure, thus reducing considerably the risk of breakdown due to metallic deposits in the magnet chamber.

Preferably, the hollow slide valve member is formed by a blind bore in the end of the control rod, the exterior of the hollow slide valve member being provided with two annular grooves forming three separate piston sections slidable in the axial bore, the annular groove nearer to the electromagnet being provided with openings leading into the blind bore. With that form of valve member, the force-displacement-curve of the electromagnet can easily be made appropriate to the relative positions of the control edges provided by the piston sections.

To locate the slide bearing axially, it may be accommodated in a stepped bore in the valve housing.

In order that the invention may be clearly understood and readily carried into effect, one form of pressure regulating valve in accordance therewith will now be described with reference to the accompanying drawing which represents a longltudinal section through the valve.

The drawing shows an electromagnetic pressure regulating valve 10 comprising an electromagnet 11 and a slide valve 12. The pressure regulating valve 10 has a housing 13 which consists of an electromagnet housing 14 and a slide valve housing 15 plugged into the latter so that the valve housing 13 and the electromagnet housing 14 are integral with one another. The electromagnet housing 14 accommodates a winding 16, a plate 17 conducting the magnetic flux and has a cover 18, a space 21 being formed in the interior of the housing 13 accommodating the armature 19 of the electromagnet 11. A tubular extension 22 of the slide valve housing 15 projects into the space 21, the end of the extension 22 lying opposite the end of the armature 19 and being arranged in the magnetic flux circuit of the electromagnet 11.

In a multi-stepped bore 24, the slide valve housing 15 accommodates an extension 25 of non-magnetic material which has an axial bore 26. The armature 19 is fixed to a control rod 27, mounted for axial movement in the housing 13, one end 28 of which is guided in a slide bearing 29 in the cover 18, and the other end 32 of which is formed as a hollow slide valve member 33 guided in a slide bearing formed by the axial bore 26 in the extension 25. The hollow slide valve member 33 is formed by a blind bore 34 in the end of the control rod 27 and is subdivided by means of two annular control grooves 35 and 36 into three separate piston sections 37, 38 and 39 slidable in the axial bore 26. The annular control groove 36 nearer to the electromagnet is provided with openings 41 leading to the blind bore 34.

Ducts 42 which are connected to a supply port 43 in the valve housing 15 and which extend radially into the axial bore 26, are arranged in the extension 25 in the region of the control groove 35. In the region of the piston section 39, the extension 25 has recesses 44 which are in communication with a discharge port 45 in the valve housing 15. An end annular groove in the extension 25 forms a control port 46 which can be connected to a source of fluid under pressure to be regulated and which is in permanent communication with the base of the blind bore 34 forming an area on the slide valve member responsive to axial pressure from the source of fluid, in opposition to the force applied to the control rod 27 by the electromagnet 11.

The method of operation of the electromagnetic pressure regulating valve 10 is as follows: The pressure of the fluid at the control port 46 to be regulated, acts on the base of the blind bore 34 in the control rod 27 at the end 32 thereof whereas the armature 19 produces an opposing force on the control rod 27. If both forces are in equilibrium, then the control port 46 is not only isolated from the supply port 43 but also from the discharge port 45.If the pressure at the control port 46 is higher than a desired value signal generated by the electromagnet 11, then the control rod 27 is forced towards the right in the drawing whereby the piston section 39 opens the communication to the discharge port 45 and fluid under pressure can flow away from the load port 4 through the blind bore 34 and the openings 41 until equilibrium is once again established between the opposing forces acting on the control rod 27.

If the reverse occurs and the pressure at the load port 46 is too low in relation to the electromagnetically applied counterforce, then the control rod 27 is displaced towards the left in the drawing whereby the piston section 37 opens the communication between the supply port 43 and the load port 46. Fluid under pressure can then flow through this communication until the desired pressure has built up at the control port 46 and equilibrium of the opposing forces on the control rod 27 again prevails.

Thus, desired pressures may be controlled within a predetermined range by varying the electrical signal applied to the winding 16 of the electromagnet 11.

It is an advantage that, due to the nonmagnetic extension 25 and the magnetic flux conducting plate 17, no magnetic flux flows through the control rod 27 in the region of its ends 28 and 32 so that magnetic jamming of the rod is prevented. Furthermore, the extension 25 permits easy matching of the position of the control edges on the slide valve 12 formed by the piston sections 37-39, to the behaviour of the displacement-force-curve of the electromagnet 11.

Since the discharge port 45 is remote from the control port 46 where the pressure of the source of fluid to be regulated prevails, the electromagnet 11 is only exposed to the discharge pressure, which considerably reduces the risk of breakdown of the electromagnet due to metallic deposits from the fluid under pressure arriving in the magnet chamber.

Finally, combining the hollow slide valve 33 with the control rod 27, leads to a simple and compact construction of the pressure regulating valve 10.

WHAT WE CLAIM IS: 1. An electromagnetic pressure regulating valve comprising a housing, an electromagnet arranged in the housing, a control rod mounted at each of its ends for axial movement in the housing and an armature of the electromagnet fixed to the control rod, one end of the control rod being formed as a hollow slide valve member mounted in a non-magnetic slide bearing, the valve member and the slide bearing forming a slide valve controlling communication between respective pressure fluid supply and discharge ports and a control port, the control port being arranged to be connected to a source of fluid under pressure to be regulated and being in permanent communication with an area of the slide valve member responsive to axial pressure in opposition to the force applied to the control rod by the electromagnet, so that the pressure of the source of fluid to be regulated can be controlled by the control valve in accordance with the force provided by the electromagnet.

2. A pressure regulating valve according to claim 1, in which the slide valve is arranged in a valve housing which is integral with the electromagnet housing.

3. A pressure regulating valve according to claim 1 or claim 2, in which the supply and discharge ports lead radially into an axial bore in the slide bearing accommodating the hollow slide valve member.

4. A pressure regulating valve according to claim 3, in which the controport forms an extension of the axial bore and leads directly into the interior of the hollow slide valve member.

5. A pressure regulating valve according to claim 3 or claim 4, in which the hollow slide valve member is formed by a blind bore in the end of the control rod, the exterior of the hollow slide valve member being provided with two annular grooves forming three separate piston sections slidable in the axial bore, the annular groove nearer to the electromagnet being provided with openings leading into the blind bore.

6. A pressure regulating valve according to claim 2 and any one of claims 3 to 5 in which the electromagnet housing accommodates a winding, a magnetic flux conducting plate and has a cover at one of its ends, the slide valve being plugged into the electromagnet at the end thereof opposite to the cover.

7. A pressure regulating valve according to claim 6, in which the slide valve housing is provided with a tubular extension plugged into the electromagnet housing so as to project into the winding and form a part of the magnetic circuit with its inner end located in the vicinity of the armature.

8. A pressure regulating valve according to any preceding claim, in which the slide bearing is accommodated in a stepped bore in the valve housing.

9. An electromagnetic pressure regulating valve substantially as herein described with reference to the accompanying draw ing.

ing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. of the source of fluid to be regulated prevails, the electromagnet 11 is only exposed to the discharge pressure, which considerably reduces the risk of breakdown of the electromagnet due to metallic deposits from the fluid under pressure arriving in the magnet chamber. Finally, combining the hollow slide valve 33 with the control rod 27, leads to a simple and compact construction of the pressure regulating valve 10. WHAT WE CLAIM IS:

1. An electromagnetic pressure regulating valve comprising a housing, an electromagnet arranged in the housing, a control rod mounted at each of its ends for axial movement in the housing and an armature of the electromagnet fixed to the control rod, one end of the control rod being formed as a hollow slide valve member mounted in a non-magnetic slide bearing, the valve member and the slide bearing forming a slide valve controlling communication between respective pressure fluid supply and discharge ports and a control port, the control port being arranged to be connected to a source of fluid under pressure to be regulated and being in permanent communication with an area of the slide valve member responsive to axial pressure in opposition to the force applied to the control rod by the electromagnet, so that the pressure of the source of fluid to be regulated can be controlled by the control valve in accordance with the force provided by the electromagnet.

2. A pressure regulating valve according to claim 1, in which the slide valve is arranged in a valve housing which is integral with the electromagnet housing.

3. A pressure regulating valve according to claim 1 or claim 2, in which the supply and discharge ports lead radially into an axial bore in the slide bearing accommodating the hollow slide valve member.

4. A pressure regulating valve according to claim 3, in which the controport forms an extension of the axial bore and leads directly into the interior of the hollow slide valve member.

5. A pressure regulating valve according to claim 3 or claim 4, in which the hollow slide valve member is formed by a blind bore in the end of the control rod, the exterior of the hollow slide valve member being provided with two annular grooves forming three separate piston sections slidable in the axial bore, the annular groove nearer to the electromagnet being provided with openings leading into the blind bore.

6. A pressure regulating valve according to claim 2 and any one of claims 3 to 5 in which the electromagnet housing accommodates a winding, a magnetic flux conducting plate and has a cover at one of its ends, the slide valve being plugged into the electromagnet at the end thereof opposite to the cover.

7. A pressure regulating valve according to claim 6, in which the slide valve housing is provided with a tubular extension plugged into the electromagnet housing so as to project into the winding and form a part of the magnetic circuit with its inner end located in the vicinity of the armature.

8. A pressure regulating valve according to any preceding claim, in which the slide bearing is accommodated in a stepped bore in the valve housing.

9. An electromagnetic pressure regulating valve substantially as herein described with reference to the accompanying draw ing.

ing.