GB2174787A

GB2174787A - Valve

Info

Publication number: GB2174787A
Application number: GB08607407A
Authority: GB
Inventors: Karl Rein
Original assignee: Hoerbiger Ventilwerke GmbH and Co KG
Current assignee: Hoerbiger Ventilwerke GmbH and Co KG
Priority date: 1985-04-03
Filing date: 1986-03-25
Publication date: 1986-11-12
Also published as: FR2580054B1; DE3607659A1; BE904534A; IT8619829A0; FI861280A; JPS61233275A; FR2580054A1; IT1189077B; IT8619829A1; GB8607407D0; FI861280A0

Abstract

A device for controlling the delivery rate of compressors is provided with a flap valve for throttling and blocking the section of passage of the suction line. The flap valve comprises a valve housing (1) having a through duct (2), in which the flap (3) is rotatably mounted about a shaft (4) arranged transversely to the longitudinal axis of the through duct (2). In order to obtain an integrated unit having few component parts, the shaft (4) projects into a pneumatic or hydraulic regulating cylinder (5) mounted on the side of the valve housing (1), the piston (6) of the said cylinder being guided in the cylinder (5) so as to slide in a rotationally rigidly manner, and being connected in a driving manner to the flap (3) by means of a thread (9) provided on the shaft (4). <IMAGE>

Description

SPECIFICATION Device for controlling the delivery rate of compressors The invention relates to a device for controlling the delivery rate of compressors, having a flap valve for throttling and blocking the section of passage of the suction line, the flap valve comprising a valve housing having a through duct, and the flap being rotatably mounted in the valve housing about a shaft arranged transversely to the longitudinal axis of the through duct It is known to control the delivery rate of compressors, i.e. both reciprocating compressors and rotary compressors, by altering the section of passage of the suction line by means of an adjustable flap valve. A known device having this design is described in US Patent Specification 2 991 002.In the known embodiment, the flap which alters the section of passage of the suction line is rotatably mounted in a valve housing about a shaft, which penetrates the said housing diametrally. The shaft projects at one end out of the valve housing, where it is provided with a crank arm, which is connected in a driving manner via a rod to a regulating cylinder. The said drive of the flap is expensive and occupies a relatively large amount of space outside the valve housing, where the regulating cylinder is arranged as a separate component part and the displaceable drive parts are freely accessible.

The object of the invention is to improve and simplify known control devices of the type mentioned above, such that only a few drive parts are required for the adjustment of the control flap, and only a minimum amount of space is occupied.

According to the invention, this object is attained in that the shaft projects into a pneumatic or hydraulic regulating cylinder, which is mounted on the side of the valve housing, the piston of the said cylinder being guided in the cylinder so as to slide in a rotationally rigid manner, and being connected in a driving manner to the flap via a thread provided on the shaft. In this embodiment, the rotary drive for the flap is fully integrated in the valve housing. The piston of the regulating cylinder is incorporated per se in one part of the valve housing, and acts directly upon the shaft of the flap, so that a minimum of component parts is sufficient for rotating the flap. In addition, only a small amount of space is occupied and there are no moving parts on the outside.

Rotary drive means which have a pneumatic or hydraulic cylinder, the piston of which rotates a drive shaft via a thread, are already known (DE OS 21 15707, DE OS 22 44 897, US PS 3 169 407). The known embodiments form a separate drive unit and have a complicated design, such that they present no substantial advantages for the adjustment of compressors throttle flaps when compared with known embodiments comprising a crank drive. In contrast, according to the invention, a rotary drive is provided in the case of a compressor control, wherein the rotary drive is fully integrated in the control device and is designed in accordance with its special type of application, such that the particular advantages mentioned above are obtained.

In a preferred embodiment of the invention, the shaft may engage with its thread in a threaded nut, which is formed from a hollow extension of the piston projecting beyond the shaft, the hollow extension being non-circular on the outside, preferably having a flattened or polygonal cross section, and being guided in a rotationaly rigidly manner in a corresponding recess in the valve housing. In this connection, the drive connection between the piston and the shaft and also the anti-torsion lock of the piston are combined in the extension of the said piston, the space required for the rotary drive of the trottle flap thereby being reduced still further.

In further embodiments of the invention, the piston, which is connected in a driving manner to the shaft, may be provided with a return spring, which is mounted in the cylinder chamber on one side of the piston, and which loads the piston in the direction of its end position, in which the flap opens the through duct. This ensures that the throttle valve adopts the desired position when the regulating cylinder is in the pressureless state, without any additional movable drive parts or additional space being required for the restoring force.

Finally, according to a further feature of the invention, an air duct may lead from the cylinder chamber, in which the return spring is provided, and open into the through duct of the valve housing, preferably in front of the flap in the direction of flow. In this embodiment, a single connecting bore is provided on the outside of the valve housing for the entire rotary drive, to which bore the pressure medium line for the supply and removal of the working fluid is connected.

Further details of the invention may be derived from the following description by way of example of an embodiment, which is illustrated in the drawing. This shows an axial cross section through the valve housing of the embodiment, with the flap valve.

The flap valve comprises a valve housing 1 having a through duct 2, in which a flap 3 is mounted.

The flap 3 is rotatable about a shaft 4, which penetrates the through duct 2 diametrically and which is rotatably mounted in the valve housing 1. One end of the shaft 4 projects into a regulating cylinder 5, which is mounted on the side of the valve housing 1. and in which a piston 6 slides, which piston may be acted upon on one side by a pneumatic or hydraulic pressure medium. The said pressure medium is supplied and drawn off via a connecting bore 7, which is provided in a cover 8, which closes the regulating cylinder 5 from the outside.

The shaft 4 is provided with a thread 9, which engages in the thread of a threaded nut 10, which is formed by the piston 6. In the embodiment, the piston 6 comprises a hollow extension 11, which projects beyond the shaft 4 and which is designed as a threaded nut 10. The hollow extension 11 is non-circular on the outside and engages in a corresponding guide duct 12 of the valve housing 1.

This non-circular formation cannot be clearly seen in the embodiment. Here, the extension 11 and the guide duct 12 are shown with a square cross section. However, any other type of guide, which prevents a rotation of the parts which are guided in one another, is conceivable.

A return spring 14 is mounted in the cylinder chamber 13 disposed at the rear of the piston 6, which return spring loads the piston 6 in the direction of the outer end position, in which the flap 3 adopts the position shown in the embodiment. In this position the through duct is open. Finally, an air duct 15 leads from the cylinder chamber 2 into the through duct 2 of the valve housing 1.

The flap valve illustrated and described is mounted in the suction line of a compressor, in order to control the delivery rate thereof. In this connection, the through duct 2 forms part of the suction line, the section of passage of which is controlled by rotation of the flap 3. In the position illustrated, the flap 3 is open. When a pneumatic or hydraulic pressure medium is supplied through the connecting bore 7, this pushes the piston 6 against the force of the return spring 14, the extension 11 sliding in the guide duct 12 and thus preventing a rotation of the piston 6. In this connection, the threaded nut 10, which engages in the thread 9 on the shaft 4, brings about a rotation of the shaft 4 and thus also a rotation of the flap 3 the passage of the through duct 2 thereby being throttled according to the respective position of the piston 6.

As soon as pressure is released from the regulating cylinder 5 via the connecting bore 7, the piston 6 returns to its illustrated end position under the effect of the return spring 14. The air duct 15 prevents disadvantageous pressure from building up in the cylinder chamber 13 during the regulating movement of the piston 6.

Claims

1. A device for controlling the delivery rate of compressors, having a flap valve for throttling and blocking the section of passage of the suction line, the flap valve comprising a valve housing having a through duct, and the flap being rotatably mounted in the valve housing about a shaft arranged transversely to the longitudinal axis of the through duct, characterised in that the shaft (4) projects into a pneumatic or hydraulic regulating cylinder (6) mounted on the side of the valve housing (1), the piston (6) of the said cylinder being guided in the cylinder (6) so as to slide in a rotationally rigid manner, and being connected in a driving manner to the flap (3) via a thread (9) provided on the shaft (4).

2. A device according to claim 1, characterised in that the shaft (4) engages with its thread (9) in a threaded nut (10), which is formed by a hollow extension (11) of the piston (6) projecting beyond the shaft (4), the hollow extension (11) being non-circular on the outside, and being guided in a rotationally rigidly manner in a corresponding recess (12) in the valve housing (1).

3. A device according to claim 1 or 2, characterised in that the piston (6), which is connected in a driving manner to the shaft (4), is provided with a return spring (14) mounted in the cylinder chamber (13) on one side of the piston (6), which return spring loads the piston in the direction of its end position, in which the flap (3) opens the through duct (2).

4. A device according to claim 3, characterised in that an air duct extends from the cylinder chamber (13), in which the return spring (14) is provided, and opens into the through duct (2) of the valve housing (1).