Patent Grant
11041492
This disclosure relates generally to compressors, and more specifically, to a mechanism for cutting off the flow of gas, liquid, or the combination thereof in the event of compressor failure or malfunction.
In today's world of pneumatic operations, it is hard to imagine a time when air compressors were nonexistent in factories or workshops. The fact is, in the context of machine-age history, air compressors are a relatively recent innovation. Not long ago, the air tools used in workshops typically drew power from complex systems comprised of belts, wheels, and other large components. For the most part, such machinery was too massive, heavy, and costly for smaller operations, and was therefore confined primarily to larger companies.
Today, however, air compressors are usually found at factories where products are assembled or in most places where cars are serviced, such as gas stations and auto workshops. The list of tools that run on compressed air is long, but some of the most common pneumatic tools include the following: drills, grinders, nail guns, sanders, spray guns, and staplers. The most significant benefit of the standard workshop air compressor is its compact and relatively lightweight dimensions, which stand in contrast to centralized sources of power that generally utilize large motors. Additionally, air compressors last longer, require less maintenance, are easier to move from worksite to worksite, and are far less noisy than old-fashioned machinery.
Air compression is essentially a twofold process in which the pressure of air rises while the volume drops. In most cases, compression is accomplished with reciprocating piston technology, which makes up the vast majority of compressors on the market. Every compressor with a reciprocating piston has the following parts: crankshaft; connecting rod; cylinder; piston; and valve head.
Air compressors, for the most part, are powered by either gas or electric motors—it varies by model. At one end of the cylinder are the inlet and discharge valves. Shaped like metal flaps, the two valves typically appear at opposite sides of the cylinder's top end. During the “compression” process, what the piston effectively does with its back and forth movements is create a vacuum. As the piston retracts (i.e., on its down-stroke), the space in front gets filled with air, which is sucked through the inlets from the outside or from another gas source. When the piston extends (i.e., on its upstroke), that same air is compressed and therefore given the strength to push through the discharge valve—simultaneously holding the inlet shut—and into a tank or other compressed gas receptacle. As more air is sent into the tank, the pressure gains intensity.
In certain air compressor models, the pressure is produced with rotating impellers. However, the models that are typically used by mechanics, construction workers, and crafts people tend to run on positive displacement, in which air is compressed within compartments that reduce its space. Even though some of the smallest air compressors consist of merely a motor and pump, the vast majority have air tanks. The purpose of the air tank is to store amounts of air within specified ranges of pressure until it is needed to perform work. In turn, the compressed air is used to power the pneumatic tools connected to the unit supply lines. While all of this is going on, the motor repeatedly starts and stops to keep the pressure at a desired consistency.
In order to accommodate the vast range of pneumatic tools on the market, air compressors are manufactured in both one- and two-cylinder varieties. However, compressors used by private craftspeople and contractors often contain two-cylinders that function almost identically to single cylinders, the only real difference being that two strokes occur during each revolution. Some two-cylinder machines that are marketed to the public also work in two stages, where one piston sends compressed air to another cylinder for further compression.
For most single-stage air compressors, the preset pressure limit is set to a specific pressure per square inch (“psi”). When this limit is reached, a pressure switch goes off to stop the motor. In most operations, however, there is no need to even reach the pressure limit. For that reason, the compressor's air line is set to a regulator, where the user inputs the appropriate pressure level for a given tool. The regulator is bookended by two gauges: one that comes in front to monitor the pressure of the tank, and another gauge at the end to keep the pressure of the air line in check. Furthermore, the tank may be equipped with an emergency valve that triggers in the event of a mishap with the pressure switch. On some models, the switch might connect with an unloader valve, which can help reduce stress to the tank at times when the machine is deactivated.
For certain heavy-duty industrial operations, piston compressors are considered insufficient. In order to get the pressure intensity needed for complex pneumatic and other high-powered tools, professionals will generally opt for rotary screw air compressors. Unlike the piston air compressor, which relies on pulsation, the rotary screw air compressor produces an ongoing movement to generate power.
In a rotary screw compressor, air is compressed with a meshing pair of rotors. As the screws move in rotation, fluids gets sucked in, compressed, and ejected. In order to keep leakage rates at an absolute minimum, fast rotational rates are vital throughout the operation.
While compressors often are used to compress air from the atmosphere, compressors also can be used to compress other gases and liquids, or even combinations thereof. The type of gas/liquid compressed obviously is application dependent. Nevertheless, for applications that call for compressing gas/liquid that is dangerous or otherwise harmful to humans and/or the environment, additional care must be taken to prevent exposures, whether during normal operation or during compressor breakdown or failure. Such failure or breakdown can occur when any of the compressor components such as the crankshaft, connecting rod, cylinder, piston, rotor, or valve head fail in a manner that allows gas/liquid to escape to the atmosphere or open environment.
One precaution taken for dangerous gas/liquid applications is to enclose the compressor in an airtight enclosure so that any catastrophic failure to the compressor that might vent gas/liquid to the atmosphere is trapped in the enclosure. This has proven cumbersome and inefficient since it significantly adds to the size of the compressor unit, detracts from easy access to the compressor, and can hold too much heat. Accordingly, a better apparatus is needed for preventing gas/liquid exposures during compressor failure or breakdown.
In one embodiment, the present invention includes a means for cutting off the flow of gas or liquid (or a combination thereof) in the event of compressor failure or breakdown. In this embodiment, the gas/liquid flows from its source through one or more passageways into a first input chamber, and also through one or more other passageways into a second input chamber, where the first and second input chambers are separated by a stop plunger. During the down-stroke of the piston, the gas/liquid in the first chamber passes (or is drawn) through an inlet valve of the piston bore, and during the up-stroke of the piston, that gas/liquid is forced through an outlet valve of the piston bore to a tank or other compressed gas/liquid receptacle. So long as the compressor operates normally, the pressure in the two input chambers (i.e., on each side of the stop plunger) will be substantially equal, thereby keeping the stop plunger in place. If, however, the compressor fails in a manner that exposes gas/liquid in the piston bore to the atmosphere, or otherwise results in a decrease in pressure in the piston bore, the pressure in the first input chamber will fall below the pressure in the second input chamber, thereby causing the stop plunger to move to a position in which it blocks the flow of gas/liquid from entering the inlet valve of the piston bore. In that case, harmful gas/liquid from its source will cease (or substantially cease) flowing, thereby preventing harmful gas/liquid exposures during compressor failure or breakdown.
The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present invention. While the invention in not limited to the following drawings, it may be better understood by reference to one or more of them in combination with the detailed description of specific embodiments presented herein. Moreover, while some of the descriptions of the drawings refer to “gas” being used, it should be understood that liquids (or a gas/liquid combination) could also be used without departing from the disclosed invention.
Various features and advantageous details are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known starting materials, processing techniques, components, and equipment are omitted so as not to unnecessarily obscure the invention in detail. It should be understood, however, that the detailed description and the specific examples, while indicating embodiments of the invention, are given by way of illustration only, and not by way of limitation. Various substitutions, modifications, additions, and/or rearrangements within the spirit and/or scope of the underlying inventive concept will become apparent to those skilled in the art from this disclosure.
As gas enters input passageway 120 and input chamber 130b, it flows to (and through) gas outlet 160, as shown by the exiting arrows in
If the compressor fails in a manner that exposes gas in the piston bore (or anywhere at or downstream of gas outlet 160) to the atmosphere, or otherwise results in a decrease in pressure in the piston bore, the pressure in input chamber 130b will fall below the pressure in input chamber 130a because chamber 130b will essentially be open to the atmosphere due to its connection to the piston bore. The pressure differential between chamber 130a and 130b will then cause stop plunger 140 to move to a position against gas outlet 160, thereby blocking the flow of gas from entering gas outlet 160 and the inlet valve of the piston bore. In that case, harmful gas from the gas source (being delivered through gas passageways 110 and 120) will cease flowing, thereby preventing harmful gas exposures during compressor failure or breakdown.
While various dimensions and geometries of gas block 100 and its constituent components are shown in
In yet another embodiment, the sum of the cross-sectional size of gas passageways 120 are made smaller than the sum of the cross-sectional size of the inlets to the piston bore. This size relationship ensures that in the event the piston bore loses pressure (or is exposed to the atmosphere) the gas pressure in input chamber 130b will drop below the gas pressure in input chamber 130a. As described above, the pressure differential between chamber 130a and 130b will then cause stop plunger 140 to move to a closed position against gas outlet 160, thereby blocking the flow of gas from entering gas outlet 160 and the inlet valve of the piston bore. In that case, gas from the gas source (being delivered through gas passageway 110 and 120) will cease flowing, thereby preventing gas exposures during compressor failure, breakdown, or other pressure losses.
In operation, gas is supplied from an external source to gas input passageway 152, as depicted by the arrow showing gas flow into that passageway. Given this exemplary embodiment's structure and assuming stop plunger 153 is in its open position, gas supplied to gas input passageway 152 enters stop plunger 153, flows through gas passageway 154, and then flows through gas passageway 156. Pressure from the supplied gas will exert a force against poppet 157 and, if that pressure exerts a force on poppet 157 greater than the combined force exerted on poppet 157 by spring 158 and the gas pressure in gas output passageway 159, poppet 157 will open, thereby allowing gas to flow into gas output passageway 159. Except as described in more detail below, gas will continue to flow from gas input passageway 152 to gas output passageway 159 as long as the force exerted on poppet 157 by the input gas exceeds the combined force exerted on poppet 157 by spring 158 and the gas in gas output passageway 159.
The gas in gas output passageway 159 then flows as conventionally understood, i.e., into a compressor's piston bore (not shown). This described gas flow occurs at least on the down-stroke of the piston and ceases upon the piston's upstroke, at which point gas is forced through an outlet valve (not shown) to a tank or other compressed gas receptacle (not shown). (Note that due to the design of gas block 151, during the piston's upstroke, gas will not reverse flow across/through poppet 157 because poppet 157 will remain closed due to the combined force exerted on poppet 157 by spring 158 and the gas in gas output passageway 159 exceeding the input gas pressure.) Throughout this cycle, i.e., during normal compressor operation, gas pressure in each of gas passageways 152, 154, and 156 is substantially equal, thereby causing stop plunger 153 to remain in its open position (as shown). Movement of stop plunger 153 can be retarded (to deter its movement during shipping, installation, minor pressure differentials, vibration, etc.) by one or more o-rings 161. Other movement retarding mechanisms could also be used instead of (or in combination with) o-ring 161, such as one or more springs, c-rings, or even merely friction between stop plunger 153 and gas block 151.
If the compressor fails in a manner that exposes gas in the piston bore (or anywhere at or downstream of poppet 157) to the atmosphere, or otherwise results in a decrease in pressure in the piston bore, the pressure in gas output passageway 159 will fall below the pressure in gas passageways 152, 154, and 156 because gas output passageway 159 will essentially be open to the atmosphere due to its connection to the piston bore. This pressure differential will then cause poppet 157 to temporarily open until the pressure differential causes stop plunger 153 to move to its closed position against gas stop 155, thereby blocking the flow of gas from entering gas passageway 156, gas output passageway 159, and the piston bore. In that case, harmful gas from the gas source (being delivered through gas passageways 152, 154, 156, and 159) will cease flowing, thereby preventing harmful gas exposures during compressor failure or breakdown.
While various dimensions and geometries of gas block 151 and its constituent components are shown in
Although the invention(s) is/are described herein with reference to specific embodiments, various modifications and changes can be made without departing from the scope of the present invention(s), as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention(s). Any benefits, advantages, or solutions to problems that are described herein with regard to specific embodiments are not intended to be construed as a critical, required, or essential feature, or element of any or all the claims.
Unless stated otherwise, terms such as “first” and “second” are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The terms “coupled” or “operably coupled” are defined as connected, although not necessarily directly, and not necessarily mechanically. The terms “a” and “an” are defined as one or more unless stated otherwise. The terms “comprise” (and any form of comprise, such as “comprises” and “comprising”), “have” (and any form of have, such as “has” and “having”), “include” (and any form of include, such as “includes” and “including”) and “contain” (and any form of contain, such as “contains” and “containing”) are open-ended linking verbs. As a result, a system, device, or apparatus that “comprises,” “has,” “includes,” or “contains” one or more elements possesses those one or more elements but is not limited to possessing only those one or more elements. Similarly, a method or process that “comprises,” “has,” “includes,” or “contains” one or more operations possesses those one or more operations but is not limited to possessing only those one or more operations.
This application is a divisional application of, and hereby claims priority under 35 U.S.C. § 120 to, pending U.S. patent application Ser. No. 15/440,847, entitled “Compressor Gas Cutoff,” by inventor Donald R. McMullen, filed on 23 Feb. 2017.
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| Number | Date | Country | |
|---|---|---|---|
| 20200003204 A1 | Jan 2020 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15440847 | Feb 2017 | US |
| Child | 16566715 | US |
