GB2143621A

GB2143621A - A pressure regulator

Info

Publication number: GB2143621A
Application number: GB08418286A
Authority: GB
Inventors: Friedrich Bauer
Original assignee: ENFO Grundlagen Forschungs AG
Current assignee: ENFO Grundlagen Forschungs AG
Priority date: 1983-07-19
Filing date: 1984-07-18
Publication date: 1985-02-13
Also published as: DE3423784A1; FR2549567B1; GB8418286D0; GB2143621B; AT385137B; IT1176393B; ATA264583A; IT8421910A0; FR2549567A1; IT8421910A1

Abstract

In a pressure regulator comprising a diaphragm (5) acted upon by inlet pressure against the force of a spring (6), a connection duct (16) having a narrow cross-section is provided between the inlet (2) and the outlet (3), and a closure member (14) connected with the diaphragm (5) controls a discharge aperture (17) provided additionally to the inlet (2) and outlet (3). The tension of spring (6) is adjustable by a screw (8). <IMAGE>

Description

SPECIFICATION A reverse pressure regulator The invention relates to a reverse pressure regulator which converts variations in the primary pressure, delivered thereto at the inlet, into oppositely phased variations in the secondary pressure discharged at the outlet, having a housing in which there is disposed a diaphragm which is acted upon by the primary pressure against the force of a spring and controls a regulator valve, a discharge aperture which leads away from the outlet side being provided in addition to the outlet and the inlet for the pressure medium.

Pressure regulators of this type of construction are used to actuate adjusting drives in dependence on the respective operating pressure of pneumatic systems, e.g. when regulating the amount delivered by compressors. The speed of the drive machine or a throttle apparatus installed in the suction line, for example, can be adjusted by means of the pressure regulator in dependence on the final pressure of the compressor.

In the case of the known reverse pressure regulators of the type of construction initially indicated the sealing member, of the regulator valve, which is connected in a driving mannertothe diaphragm, conrols a connection duct between the inlet side and the outlet side of the regulator housing. This connection duct is kept open by the spring acting on the diaphragm as long as a relatively low pressure prevails on the inlet side. In this connection essentially the entire inlet pressure is transmitted through the open connection duct to the outlet side. As soon as the primary pressure delivered at the inlet overcomes the force of the diaphragm spring, the regulator valve closes, such that the delivery of pressure medium to the outlet side is progessively prevented.On account of the flowing-away of pressure medium through the discharge aperture leading away from the outlet side the secondary pressure prevailing at the outlet subsequently decreases as the primary pressure increases.

These known regulators operate perfectly satisfactorily from the point of view of function. Owing to the discharge aperture, however, which is indispensable for their function and is permanently open, they are constantly consuming pressure medium. This consumption of pressure medium occurs precisely when full pressure has not yet built up at the inlet, i.e. during an operating phase in which there is too little pressure medium. As a result of this, in addition to an excess consumption of energy, the build-up of operating pressure, e.g. in the case of a continuous regulation of the amount delivered by a compressor, is delayed.

The invention is based on the object of improving the known reverse pressure regulators in such a way that a permanent flowing-away of pressure medium and the disadvantages and losses associated therewith are avoided.

The pressure regulator according to the invention is set out in claim 1 of the claims of this specification.

In contrast to the previously known constructions, with the pressure regulator according to the invention it is not the connection duct between the inlet side and the outlet side which is controlled but, on the contrary, the discharge aperture. As a result of this losses caused by the excess discharge of pressure medium through the discharge aperture are to a large extent avoided. The discharge aperture controlled by the regulator valve is only open when the primary pressure on the inlet side is too great, i.e. too much pressure medium is present in any case.

The pressure regulator according to the invention can be used with particular advantage for regulating compressors, in particular for continuously regulating the inlet valve of screw compressors. In this connection the overall arrangement is substantially simplified since only a simple adjusting cylinder is required for actuating the inlet valve. When pressure is building up the adjusting cylinder is acted upon by pressure via the pressure regulator according to the invention, as a result of which the inlet valve is continuously opened against the force of its closing spring. The discharge aperture remains closed until full pressure is reached such that no pressure medium is consumed.The regulator only starts to consume pressure medium - simultaneously with the closing movement of the inlet valve - when the end pressure rises above the nominal value, i.e. the compressor conveys too much. When the inlet valve is closed during idling, the regulator consumes the greatest amount of pressure medium and thereby also ensures the desired discharge effect for the amount of leakage of the inletvlave, which, as is known, is necessary for maintaining lubrication in the case of screw compressors.

In a further development of the invention the connection duct can be provided in a partition between the inlet and the outlet of the housing, which partition is penetrated by the sealing member of the regulator valve or the drive thereof with predetermined clearance. As a result of this it is easy to connect the drive between the diaphragm and the discharge aperture, no sealing with the partition which might impair the accuracy of regulation, for example occurring by friction, being necessary at all.

The connection duct can, however, consist entirely or partially of at least one bore in the partition between the inlet and the outlet of the housing or of a by-pass duct.

Further details and advantages of the invention will result from the following description of the pressure regulator according to the invention with reference to a drawing showing an axial centre section of an embodiment by way of example.

The reverse pressure regulator illustrated includes a husing 1 with an inlet 2 for the primary pressure and an outlet 3 for the secondary pressure. Placed on the housing lisa cover 4 which clamps a diaphragm 5 and accommodates a spring 6 loading the diaphragm 5. The spring 6 is supported on a spring plate 7 whih can be adjusted to preset the tension of the spring 6 by means of a screw 8. At its other end the spring 6 abuts on a diaphragm plate 9 which is secured to the diaphragm 5 by means of a nut 10.

Between the inlet 2 and the outlet 3 the housing 1 is divided by a partition 11 into an inlet pressure chamber 12 and an outlet pressure chamber 13. A regulator valve 15 conrols discharge to the atmosphere of pressure medium from the outlet pressure chamber 13 through a discharge aperture 17 into a discharge duct 18 independently of the outlet 3. The sealing member 14 of a regulator valve 15 is secured to the diaphragm plate 9 of the said diaphragm and penetrates the partition 11 with predetermined clearance such that a connection duct 16 having a narrow corss-section is formed between the inlet pressure chamber 12 and the outlet pressure chamber 13.

In the pressureless state, shown in the drawing, the regulator valve 15 is closed. Pressure medium delivered through the inlet 2 passes out of the inlet pressure chamber 12 through the connection duct 16 into the outlet pressure chamber 13, in which there builds up pressure which is available at the outlet 3 as secondary pressure. The pressure regulator remains in this position until full nominal pressure has built up. During this period the regulatorvalve 15 remains closed so that there are no pressure losses through the discharge duct 18. The nominal pressure can be set by preselecting the tension of the spring 6 by means of the screw 8.

As soon as the primary pressure acting in the inlet pressure chamber 12 on the diaphragm 5 overcomes the force of the spring 6 the sealing member 14 is lifted off the discharge aperture 17 and thus discharge through duct 18 increases as the pressure increases. As a result of this the pressure in the outlet pressure chamber 13, and the secondary pressure generated at the outlet, drop. Depending on the regulating arrangement selected overall there is triggered as a result an adjusting movement which counter-acts a further increase in the primary pressure. As soon as the pressure drops to the nominal value the regulating valve 15 closes the discharge duct 18 once more such that the secondary pressure does not drop any further.

By controlling discharge through the duct 18 it is ensured that during the buiid-up of pressure when there is still too little pressure medium available, no loss in pressure is caused by the discharge of pressure medium through the discharge duct 18.

The discharge aperture 17 is only opened when the nominal pressure is reached, whereupon pressure medium can flow away without any disadvantage since in this operating phase too much pressure medium is available in any case. During the continuous throttle regulation of screw compressors, the release of pressure medium during idling is actually desirable, since in order to maintain lubrication of the compressor the conveying of the pressure medium cannot be completely prevented and the quantity of pressure medium conveyed thereby beyond the output demand is removed by the discharge facility.

In the embodiment the connection duct 16 is formed by the clearance between the sealing member 14 of the regulating valve 15 and the passage in the partition 11. One or more bores can also be provided in the partition 11 either in addition to this clearance or instead thereof, these bores forming the connection duct. A separate by-pass duct between the inlet and the outlet is also possible within the scope of the invention. The drive connection between he diaphragm and the sealing body of the regulating valve can then be sealed, for example by a separate sealing membrane during the course of the transmission of force for the actuation of the regulating valve.

Claims

1. A reverse pressure regulator which converts variations in the primary pressure delivered thereto at the inlet into oppositely phased variations in the secondary pressure discharged at the outlet, having a housing, in which a diaphragm is disposed which is acted upon by the primary pressure againstthe force of a spring and controls a regulating valve, a discharge aperture leading away from the outlet side being disposed in addition to the inlet and the outlet for pressure medium, a connection duct having a narrow cross-section provided between the inlet and the outlet and a regulating valve having a discharge aperture whose opening is controlled by a sealing member connected to the diaphragm in phase with the primary pressure.

2. A pressure regulator as claimed in claim 1, wherein the connection duct is provided in a partition between the inlet and outlet of the housing, which partiion is penetrated by the sealing member of the regulating valve or the drive thereof with predetermined clearance.

3. A pressure regulator as claimed in claim 1 or claim 2, wherein the connection duct consists totally or partially of at least one bore in the partition between the inlet and the outlet of the housing.

4. A pressure regulator substantially as herein described with reference to and as illustrated in the accompanying drawing.