This invention relates to slide valve assemblies and in particular to slide valve assemblies for controlling a flow of material and utilizing a flexible membrane for achieving an effective seal between a reciprocable closure member and the valve body.

It has been proposed in British patent specification 1383059 to provide a slide valve assembly comprising a valve body having an opening through which material is arranged to pass under the control of the valve, a closure member reciprocally movable across the opening, and a flexible membrane extending around and secured to the closure member, the membrane also being secured to the valve body.

Such assemblies are particularly suitable for controlling the flow of powder materials to prevent such materials from escaping from the assembly.

An object of the invention is to provide an improved slide valve assembly.

According to the invention a slide valve assembly comprises a valve body defining an opening for material, a closure member reciprocally movable across the opening to prevent the flow of material through the opening, a flexible membrane carried by the closure member and having a portion movable with the closure member and another portion fixed in relation to the valve body, and resilient means associated with the closure member, the closure member, upon reaching a closed position of the valve, abutting the valve body through the resilient means to effect a seal between the closure member and the valve body.

Preferably the assembly comprises guide means for the closure member and the valve body includes a slot through which the closure member is movable, said other portion of the membrane being fixed between the slot and the guide means.

Conveniently the resilient means is carried by the closure member over a region of the closure member which is arranged to abut against the valve body in the closed position, and the membrane extends around and over said region of the closure member.

In one arrangement the opening in the valve body is circular and the closure member is of corresponding shape to occupy the opening in the closed position, the leading edge of the closure member being semicircular and said leading edge constituting said region of the closure member. Alternatively the opening may be rectangular or of other shapes, and the closure member is shaped accordingly.

The membrane may be secured to the closure member towards the leading end thereof by releasable fixing means. The portion of the membrane which is fixed may be clamped between the valve body and the guide means so as to be located around the slot in the valve body to effect a seal.

The guide means, which may also serve to carry the closure member, is conveniently releasably attached to the valve body. This enables the closure member to be readily removed for cleaning and, if necessary, to replace the membrane. In one arrangement a quick release toggle may serve to interconnect the valve body and the guide means.

The membrane may generally be in the form of a bag open at one side and in the form of a segment of a circle and the bag being open to define an opening for receiving the closure member.

The closure member may be resiliently biased towards a closed position.

Further features of the invention will appear from the following description of an embodiment of the invention given by way of example only and with reference to the drawings, in which:

Fig 1 is a perspective view of the slide valve assembly, shown assembled,

Fig 2 is a perspective view corresponding to Fig 1 with the slide valve disassembled,

Fig 3 is a view on the line 3-3 in Fig 2, and

Fig 4 is a view on the line 4-4 in Fig 1.

Referring to the drawings a slide valve assembly is shown which is intended to be located in circular section piping or ducting 10 along which is carried flowable material, for example powder or liquid material.

A valve body 12 is secured to the pipe or ducting 10 through flanged connections using spaced apart flanges 13 and 14 at each end of the body 12. The flanges 13 and 14 extend circurnferentially around a cylinder 16 which defines an opening 11 for material and in which is formed a semicircular slot 18 for receiving a valve guide body 20. The slot 18 also provides an aperture through which a reciprocal closure member 22 is movable between closed and open positions.

The valve guide body 20 extends generally radially of the central axes 24 of the valve body and includes a channel 26 through which the closure member 22 extends, and lateral guides 28 in which bearing strips 30 on the closure member 22 locate.

The leading end of the guide body 20 provides generally semicircular edges 32 which locate with the cylinder 16 around the edges of the slot 18.

The guide body 20 is releasably securable to the body 12 through axially directed flanges 34 on opposite sides of the body 12 which flanges each carry a clip arrangement 35 pivotable between a clamping position (Fig 1) and a release position (Fig 2), this arrangement having an operating handle 35A and a clip 35B, the clip engaging with a hook 36 on the valve body and being drawn towards a clamped position of Fig 1 when the body 20 is fixed to the valve body 12.

Alternatively the guide body 20 is coupled to the valve body 12 with nuts and bolts.

The closure member 22 generally takes the form of a plate 38 of which the leading end 39 is semicircular and is fitted with resilient means 40 which extends over and around the semicircular edge of the plate 38. The resilient means 40 can take several forms, for example a strip of resilient material, such as rubber or foam, adhered to the plate 38, or a moulding of resilient material slotted to received the edge of the plate, or any other convenient arrangement fulfilling the purpose to be described. In a further arrangement the resilient means 40 is a fluid or air filled tube.

The closure member 22 may be manually or power operated a manually operated version being shown. Manual operation may be by means of a spring loaded handle 42 carried on the member 22 and by movement against the spring is releasable from the frame of the body 20. Release of the closure member 22 from the open position for movement towards a closed position in the illustrated arrangement is by lifting the handle 42 against the spring to release the engagement with a hole in a cross bar 29 of the body 20. The closure member 22 can then be moved towards a closed position of the valve.

To ensure resilient tensioning of the closure member 22 into a closed position there is provided a tensioner (Fig 4) including a rotatable handle 50 carried on a threaded shaft 51 and mounted between the body 20 at one end and the rear end of the closure member 22 at the other end. a spring 52 being located around the shaft 51 so that on rotation of the handle 50 the spring is compressed and urges the closure member 22 resiliently towards a closed position compressing the resilient means 50 at the loading edge of the closure member 22 to the required amount. Manual operation is used where infrequent operation of the valve is required. Alternatively the closure member 22 may be attached to a pneumatic or hydraulic cylinder (not shown).

The closure member 22 also comprises a membrane 44 of flexible sheet material, for example rubber, rubberised fabric, plastic sheet or other cleanable, flexible material suited to the

environment in which the valve operates. The membrane 44 includes two segmental portions 45 joined together over two edges of the segment by strips 45 A and open over the part circular edges, thereby defining a bag into the open side of which is received the leading end of the plate 38 with a circular edge of the plate located up against the junction between the segmental portions 45.

There is also provided releasable fixing means for securing the leading end of the plate 38 to the membrane 44. In Fig 1 this fixing means is shown as a nut and bolt 46. Other fixing means may be employed, for example a strip of material may be fixed to the inside of the membrane bag and the strip locates in a slot formed in the plate 38 and leading to an opening in the plate (this arrangement not being shown in the drawings). At the trailing edges of the membrane 44 the membrane is arranged to be clamped between the edges of the slot 18 and the guide body 20 to seal the body 20 in the slot 18. The leading end of the membrane is free to move in and out of the opening 11 in the body when the closure member 22 is moved in and out of a closed position and the membrane prevents any material within the cylinder 16 from escaping through the slot 18 and the valve assembly.

The guide body 20 is fitted with a gasket member 31 of semi circular shape which fits onto the leading semi circular edge 32 of the body 20 and formed of resilient material, for example latex applied over a wire frame. The member 31 provides an upstanding lip 48 to form a seal for the body 20 against the valve body 12. It will be seen that the guide body 20, the slot 18 and the shaping of the membrane 44 present co-operating tapered shapes ensuring that the parts fit closely together when in the assembled condition. The body 20 is provided with stops 49 to act as an abutment and prevent the body 20 from being urged too far towards the body 12.

When the valve assembly is in the open position the closure member is fully withdrawn from across the opening 11, withdrawing with it the leading end of the membrane 44 and allowing material to pass freely through the opening 11. When it is required to close the opening 11 the closure member is operated towards a closed position in which the leading end of the

plate 38 abuts the inside of the cylinder 16 around its internal periphery opposite to the slot 18. Due to a presence of the resilient material 40, located between the plate 38 and the membrane 42 a satisfactory seal is obtained. The arrangement avoids the presence of resilient material on the internal surface of the cylinder 16 which may be contaminated by material passing through the opening 11. At the same time an adequate seal is made despite the possible presence of material on the inside wall of the cylinder.

To ensure that the resilient material 40 is not retained in a fully compressed position after closure of the valve there is provided the resilient means 50, 51, 52 between the handle 42 or other operating means and the closure member 22, whereby the closure member is urged at a predetermined force into a closed position.

It will be seen that the slide valve assembly shown and described is effective in controlling the flow of materials along piping or ducting without the likelihood of products escaping through the valve assembly or blocking the valve assembly. At the same time the assembly is readily taken apart for any cleaning requirement or replacement of the membrane. Indeed the membrane may be replaced after each operation of the valve by releasing the closure assembly from the body 12 and taking off the membrane 44.

The assembly is adaptable for various duties and materials and the membrane may be changed to suit specific requirements. The valve body may incorporate axial extensions of piping so that the body becomes permanently united with the ducting for the product. Various different drive arrangements may be employed for the valve and the drive arrangements may be adapted for automatic operation.

The valve may equally well be applied to pipes or ducts not of circular section by adapting the shape of the closure member 22 and the associated body 20 to the duct shape. Thus the duct may be of elliptical, rectangular or other shape, in cross section.