Title of Invention

"AN AUTOMATIC DEVICE FOR REMOVING INTERNAL SEALS FROM THE VALVES OF LPG CYLINDERS AT HIGH SPEED"

Abstract

The present invention relates to an automatic device for removing internal seals from the valves of LPG cylinders at high speed comprising: an outer shell, a slide block within the outer shell, a tool carrier within the said slide block having first slot and a pivot pin, a foot fixed to the lower portion of the said slide block and extending out below the said slide block, the lower portion of the foot being curved sideways into a toe. an extractor having a curved cam slot, fixed pivotably on the said pivot pin within the tool carrier and extending through a second slot in the slide block, the lower portion of the extractor being narrowed down to a tip, a spring placed between the slide block and the tool carrier to separate the two, a pneumatic piston fitted in the top of the outer shell to actuate the tool carrier, second spring between the outer shell and side block to push the slide block downwards, first pneumatic valve to sense the upward movement of the slide block and a second pneumatic valve to sense the downward movement of the said pneumatic piston.

Full Text

The present invention relates to an automatic device for removing internal seals from the valves of LPG cylinders at high speed. BACKGROUND LPG is a widely used cooking fuel in many parts of the world. This gas is supplied to the customers in cylinders. The cylinders contain a valve, which serves for both filling & withdrawal of the gas. At the point of use a pressure regulator is fitted onto the valve by the user. The regulator opens the valve and regulates the out flow of gas to connected appliances. Various types and sizes of valves are used in the industry. One common feature of these valves is that a means of sealing the joint between the valve and the regulator is always provided. LPG is a highly flammable gas and this seal ensures that no leak to the atmosphere takes place when the gas is being withdrawn from the cylinder. Fig. 1 of the accompanying drawings shows a very commonly used design of such an LPG valve (1) mounted on a cylinder (c). The mouth of the valve contains an internal recess (2) into which a seal (3) is fitted. Fig. 2 of the accompanying drawings shows how this seals the connection between the LPG valve and the regulator nozzle (4). A leak from this seal is especially hazardous because it can take place undetectably at the customer premises, where no special precautions against accidental ignition are in place. The danger is further accentuated by the fact that these cylinders are often used in confined kitchens in close proximity to burner flames and unprotected electrical fittings. Since the seal is located near the open mouth of the LPG valve. It can suffer environmental degradation, mechanical damage and deposition of foreign matter. Causing it to loose its sealing capability. The above combination of factors make control of seal integrity a critical safety issue. In order to avoid these hazards it is necessary for the supplier to ensure the integrity of the seal before the cylinder is sent to the customer. This control is done within the filling plant according to one of two procedures. One is to replace the seal with a new one every time a cylinder comes in for refilling. And then use a leak testing device which checks for seal leakage. Another method is to use a leak testing device to check the seal and to change the seals found to be leaking. Both these methods require that the seal be somehow removed from the valve before a new one is installed. If the seal is an internal one the removal is difficult because of the very confined space for access of the removal tool and poor visibility of the operation for the operator. Careless removal can scratch the sealing groove inside the valve and cause even a new seal to leak. Such a valve is permanently damaged and has to be discarded. The method currently used for removing the seal is to pull it out manually using a hooked tool. This method is very vulnerable to variations in operator skill. The risk of scratching the surface of the sealing groove inside the valve is high. This method is also much too slow to handle the high production rates of modern filling Plants. The object of this invention is to obviate the above drawbacks by removing seals automatically at a high speed and independent of manual skill. To achieve the said objectives, this invention provides an automatic device for removing internal seals from the valves of LPG cylinders at high speed comprising: an outer shell, a slide block within the outer shell, a tool carrier within the said slide block having first slot and a pivot pin, a foot fixed to the lower portion of the said slide block and extending out below the said slide block, the lower portion of the foot being curved sideways into a toe, an extractor having a curved cam slot, fixed pivotably on the said pivot pin within the tool carrier and extending through a second slot in the slide block, the lower portion of the extractor being narrowed down to a tip, a spring placed between the slide block and the tool carrier to separate the two, a pneumatic piston fitted in the top of the outer shell to actuate the tool carrier, second spring between the outer shell and side block to push the slide block downwards, first pneumatic valve to sense the upward movement of the slide block and a second pneumatic valve to sense the downward movement of the said pneumatic piston. The slide block includes a flange at the upper end, a cavity, a slot and a pin at the lower end. The said pin in the slide block passes through the curved cam slot in the extractor such that the curved cam slot causes the tip of the extractor to follow a curved path as the tool carrier is actuated by the piston thereby displacing the seal from the groove in the LPG valve. The sensing of the upward movement of the slide block is carried out by a pneumatic valve receiving air supply via port in the outer shell and producing an output signal at another port. The sensing of the downward movement of the pneumatic piston is carried out by a second pneumatic valve receiving air supply at port in the outer shell and producing an output signal at another port. The invention will now be described with reference to the accompanying drawings: Fig. 1 shows a cross section of a known LPG valve showing the internal seal. Fig. 2 shows a cross section of known LPG valve with the gas regulator attached. Fig. 3 shows an isometric view of the seal removal device. Fig. 4a shows a cross section of the seal removal device in the idle condition. Fig. 4b shows a cross section of the seal removal device lowered onto the cylinder valve. Fig. 4c shows a cross section of the seal removal device when the extractor has started extending. Fig. 4d shows a cross section of the seal removal device with the extractor partly extended. Fig. 4e shows a cross section of the seal removal device with the extractor fully extended. Fig. 4f shows a cross section for the seal removal device after it has lifted off the valve, carrying the seal with it. Referring to the drawings, an automatic device, according to this invention, has following components: An outer shell (200) and a slide block (110) is fixed slidably within the outer shell and containing a flange (111) at the upper end, a cavity (112) and a slot (113) and a pin (114). A tool carrier (120) is fixed slidably within the slide block containing a slot (121) and a pivot pin (122). Further a foot (130) is fixed to the lower portion of the slide block and extending out below it. The lower portion of the foot is curved sideways into a toe (131). An Extractor (140) is also fixed pivotably on pin (122) within the tool carrier and extending slidably through slot (113) in the slide block. Containing a curved cam slot (141) engaging pin (114). The lower portion of the extractor is narrowed down to a tip (142). A spring (150) is placed between the slide block and the tool carrier to separate the two. A pneumatic piston (160) is fitted slidably in the top of the outer shell to actuate the tool carrier. The piston is being actuated via port (205) in the outer shell. A spring (170) is also provided between the outer shell & slide block to push the slide block downwards. A pneumatic valve (180) is provided to sense the upward movement of the slide block. Air supply is received via port (201) in the outer shell and an output signal is produced at port (202) when the slide block (110) moves upward. A pneumatic valve (190) is fixed to sense the downward movement of the Pneumatic piston. Air supply is received at port (203) in the outer shell and an output signal is provided at port (204) when the piston (160) moves downward. The ports (204, 203, 205, 201 & 202) are connected to a conventional pneumatic circuit. WORKING: Fig. 4a shows the device in the idle condition. In this condition the spring (170) keeps the slide block (110) down in the outer shell and the spring (150) keeps the tool carrier (120) up in the slide block, extractor (140) is thus retracted within the slide block. Fig. 4b shows the device when it has been lowered onto a cylinder valve. This lowering being accomplished by a standard pneumatic actuator (not shown) connected to the top (206) of the outer shell (200). The lower part of foot (130) has entered the mouth of the cylinder valve and the Top part (12) of the valve has contacted the lower face (115) of the slide block (110). Thus pushing it up against the action of spring (170) and actuating the pneumatic valve (180). Actuating of this valve provides a pneumatic signal at port (202) to indicate successful engagement of the device to the cylinder valve. The pneumatic circuit is organized to pressurize port (205) on receipt of this signal, pressurization this port causes the piston (160) to move downwards, forcing the tool carrier downward against the action of spring (150). Since the extractor (140) is connected to the tool carrier via pin (122) it too is forced downwards. Fig. 4c shows the device in the initial stage of this downward motion. In this condition downward movement of the tool carrier (120) has caused the extractor (140) to move downwards within the slide block. Since the cam slot (141) in the extractor engages pin (114) which is fixed to the slide block, the shape of the cam forces the extractor tip (142) to move radially outwards as the extractor moves down. In Fig. 4c this motion has caused the extractor tip (142) to touch the upper surface of the valve seal (3). Continuation of this motion causes the extractor tip (142) to lower further and also extend radially into the sealing groove (2). This displaces the seal out of the groove as shown in Fig. 4d where the extractor tip has been forced to limit its radial motion. The extractor tip is dimensioned so that in this condition it does not contact any surface of the valve. Carrying the downward movement of the tool carrier to completion causes the extractor to extend further downwards. The pin (114) now enters the upper portion of cam (141). This causes the extractor tip (142) to retract radially inwards towards the foot (130). This forces the seal further out of the groove (3) and until it is gripped between the extractor tip (142) and foot (130). This condition is shown in Fig. 4e. Further movement of the tool carrier is stopped because it is now fully seated in cavity (112) in the slide block (110). At this stage the flange (161) at the upper end of piston (160) actuates valve (190) causing a pneumatic signal to be output at port (204). This signal indicates the completion of O-ring gripping stroke. The attached pneumatic circuit lifts the device off the LPG valve on receipt of this signal. Since the O-ring is gripped between the extractor tip and the foot, it is pulled out of the LPG valve as the device lifts. This condition is shown in Fig. 4f. When the device has lifted fully, the pneumatic circuit cuts off pressure to port (205) and opens this port to the atmosphere, thus removing the down force due to piston (160). On removal to this down force the spring (150) & (170) return the device to its initial state shown in Fig. 4a. In this state the extractor retracts into the slide block and releases the seal, permitting it to fall off. A special feature of the device is that it can be easily adapted to a wide variety of groove and seal dimensions by changing the shapes of the extractor tip, the cam slot and the foot. Another special feature of the device is that the tool motions are derived in simple way from the movement of one pneumatic piston (160). This facilitates high speed operation. The entire sequence of operation shown in Fig. 4b to Fig. 4e is accomplished in a fraction of a second. I claim: 1. An automatic device for removing internal seals from the valves of LPG cylinders at high speed comprising: an outer shell, a slide block within the outer shell, a tool carrier within the said slide block having first slot and a pivot pin, a foot fixed to the lower portion of the said slide block and extending out below the said slide block, the lower portion of the foot being curved sideways into a toe, an extractor having a curved cam slot, fixed pivotably on the said pivot pin within the tool carrier and extending through a second slot in the slide block, the lower portion of the extractor being narrowed down to a tip, a spring placed between the slide block and the tool carrier to separate the two, a pneumatic piston fitted in the top of the outer shell to actuate the tool carrier, second spring between the outer shell and side block to push the slide block downwards, first pneumatic valve to sense the upward movement of the slide block and a second pneumatic valve to sense the downward movement of the said pneumatic piston. 2. An automatic device as claimed in claim 1 wherein the slide block includes a flange at the upper end, a cavity, a slot and a pin at the lower end. 3. An automatic device as claimed in claims 1 & 2 wherein the said pin in the slide block passes through the curved cam slot in the extractor such that the curved cam slot causes the tip of the extractor to follow a curved path as the tool carrier is actuated by the piston thereby displacing the seal from the groove in the LPG valve. 4. An automatic device for removing internal seals from the valves of LPG cylinders substantially as herein described with reference to and as illustrated in figures 3 to 4f of the accompanying drawings.

Documents:

799-del-2000-abstract.pdf

799-del-2000-claims.pdf

799-del-2000-correspondence-others.pdf

799-del-2000-correspondence-po.pdf

799-del-2000-description (complete).pdf

799-del-2000-drawings.pdf

799-del-2000-form-1.pdf

799-del-2000-form-19.pdf

799-del-2000-form-2.pdf

799-del-2000-form-3.pdf

799-del-2000-pa.pdf