GB2200405A - Blower for a combustible gas-air mixture - Google Patents

Abstract

Any of the mixture inadvertently leaking through the shaft seal 30' is returned from a chamber 34' to the blower intake chamber by a passage 40. The chamber 34' is also connected to atmosphere either directly through passage 50 or indirectly via passages (66, Fig. 2C) in the motor housing. <IMAGE>

Description

IMPROVED BLOWER FOR A COMBUSTIBLE GAS-AIR MIXTURE The prescnt invention relates generally to a blower for a combustible gaseous fluid or-vas-air mixture, and more particularly to improvements for obviating any leakage of the mixture as might present an explosion hazard, pollute the working environment or otherwise detract from the usefulness of the blower.

It is already well known, as exemplified by the pump of U.S. Patent No. 2,784,672, that the pump suction can be used to induce a fluid flow path from behind the impeller back into the pumping or impeller chamber. Significantly, this pump suction heretofore has not been effectively used to control the adverse effects of leaking combustible fluid that typically is handled by this type of pump.

Broadly, it is an object of the present invention to provide an improved blower in which the suction thereof, without any adverse side effect on blower efficiency and performance, is used to return leaking gas-air mixture to the suction chamber, thereby to overcome the foregoiny and other shortcomings of the prior art.

Specifically, it is an object to apply suction to a compartment behind the impeller in which gas-air leakage is collected preparatory to the return thereof to the suction chamber, but without causing the lubricant to be sucked out of the shaft bearing which by necessity in the construction of the blower is located adjacent the leakage-collection chamber and is thus unavoidably subject to the suction applied thereto, all in a manner as will subsequently be explained in detail.

An improved blower demonstrating objects and advantages of the present invention includes the previously noted gas-air leakage collection compartment behind the impeller, and which conpartment is bounded on one side by a seal and un its opposite side by a shaft-supporting bearing.In accordance witn the present invention there are two passageways in communication with said compartment, namely a first passageway connected between said compartment and the inlet of the impeller chamber for establishing an exiting flow path under suction of said impeller for any fluid, i.e. gaseous material, entering into said compartment, and a second passageway connected from atrnosp!cre to said compartment for establishing a normally inflowing flow path of air into said compartment past said compartment-bounding, bearing and having c nmunication with said exiting flow path, whe g y during blower pumping service when there is no leakage of gas-air mixture into said compartment the suction applied to the compartment draws air from atmosphere through said first passageway rather than through the bearing, and in this way the bearing is by-passed and not subject to a suction which might remove the grease and oil therefrom and cause drying out of the bearing.Yet, when there is gas-air leakage into the compartment, it is typically higher than atmospheric pressure, and is leakage which is readily returned by the blower Suction back to the intake chamber.

The above brief description, as well as other further objects, features and advantages of the present invention, will be more fully appreciated by reference to the following detailed description of presently-preferred, hut nonetheless illustrative embodiments in accordance with the present invention, when taken in conjunction with the accompanying drawings, wherein:: FIG. 1 is an end elevational view of a blower illustrating the inlet and outlet thereof, in the construction of which there can be advantageously embodied the improvements according to the present invention; FIG. 2A is a side elevational view, partly in section, of a prior art blower in which the internal structural features are illustrated as seen along line 2-2 of FIG. 1, the same being presented for contrast with the internal structural features in accordance with the present invention; FIG. 2B is a view similar to FIG. 2A, namely, a view partially in section taken along line- 2-2 of FIG. 1, but illustrating a first improved embodiment of a blower according to the present invention-:: and FIG. 2C is a view similar to FIG. 2B, but illustrating a second embodiment of an improved blower according to the present invention, As will be better understood from the description which follows, the improved blower embodiments of the present invention utilize to advantage the suction of the blower to control any yas-air mixture which inadvertently leaks down the shaft of the blower and which, if combustible, represents a- significant explosion hazard.Moreover, it is not an acceptable solution to release the leaking gas-air mixture into the atmosphere for this will pollute the area. However, while effective control of any leaking gas-air mixture is desirable, and would appear to be readily achieved using the suction of the blower impeller, this has not heretofore been possible without advcrsely affecting the efficiency and operation of the blower. For example, and as is well understood and exemplified by the fluid pump of prior U.S.

Patent No. 2,784,672, while the suction pressure can effectively be used to produce a desirable flow of cooliny fluid from the rear of the impeller back to the inlet thereof, it is not readily apparent, for reasons which will now be discussed, to be able to tlse this suction pressure to return any leaking yas-air mixture from the rear of the impeller seal back to the inlet.To best explain the difficulties, reference should be made to FIG. 1 in conjunction with FIG. 2A, which it will be understood illustrates a prior art blower 10 of the type that is typically used to urge in movement or to pump a combustible gas-air mixture, said mixture entering through an inlet 12 along pclth 60 into an impeller chamber 14 in shiah it is raised to a higher pressure, and then discharged to a point of use through an outlet 16. As illustrated in FIG. 2A, blower 10 includes a motor 18 having a motor shaft 20 extending therefrom which is appropriately supported in a bearing 22 mounted in an end wall 24 of the motor housing 26.Also appropriately mounted to be driven in rotation on the end of motor shaft 20 within the impeller chamber 14 is an impeller 28 of conventional and well understood construction.

To normally prevent leakage of gas-air mixture out of the impeller clamber 14 rearwardly along the shaft 20 there is typically provided a seal 30 which is in sealing engagement with the shaft 20, as at 32. As illustrated in FIG. 2A and also as exists in the noted U.S. Patent No.277847672 a compartent 34 is pro vided typically in m interposed position between the seal 30 and the bearing 22. In fact, compartment 34 typically has an opening 36 which bounds the seal 30 on one side, and an opposite side opening 38 which bounds the bearing 22. Moreover, it is the communication between the compartment 34 with the bearing 22 through the opening 38 that is the physical condition which primarily complicates the effective use being made in the prior art of the suction pressure of the impeller chamber 14- to remove any gas-air mixture leaking past the seal 30 rearwardly alony the shaft 20 into the compartment 34, all as now will be explained in detail.

More particularly, and although not shown in FIG. 2A, it is readily suggested by the prior art, again as exemplified by the previously noted U.S. Patent No. 2,784,672, that a passageway can be connected between the compartment 34 and the impeller inlet 14 through which the suction of the impeller chamber can be applied to compartment 34 for removal of any gas-air mixture leaking past the seal 30. However, it must be recognized that certainly at least during the initial operation of the blower 10, the seal 30 will be effective in preventing any gas-air leakage down along the shaft 20 into the compartment 34. Thus, during this period of pumping service of the blower 10, the applied suction on compartment 34 would not be performing any useful function in removing gas-air leakage, but it would nevertheless inadvertently be undermining the effective operation of the bearing 22.More particularly, and as is well understood, bearing 22, being of the ball bearing type, typically is packed with grease and oil to facilitate the rotative movement of the motor shaft 20 in the opening 38 of the motor housing wall 24. Thus, the suction pressure applied to the compartment 34, even of a nominal amount, "ould produce an undesirable tendency for movement of grease and oil from the bearing 22, and ultimately will result in a "drying out" of the bearing, and possibly cause its malfunctioning during pumping service of the blower 10.

To a significant extent, the inventive contribution is a recognition of the problem as above stated, and consists of applying novel structural feat-ures to a conventionally constructed blower which eliminates undesirable fluid leakage through the seal 30, and, at the same time, obviates any possibility of the bearing 22 drying out. This will now be explained in conjunction with a first inventive embodiment, as illustrate in FIG. 2B, in which the same conventional or unchanged structural features already described in connection with the prior art blower of FIG. 2A are illustrated by the same, but sinyle primed reference numerals, and for brevity's sake, will not again be referred to.

The structural features added to the blower 10' and which constitute the invention, consist of a first passageway 40 in impeller housing or casing 42 connected at one end, as at 44, to the suction or inlet of the pump impeller chamber 14'. As a result, suction is applied through the passageway 40 to the compartment 34' establishing an exiting flow path, designated 48, for any gaseous material within the compartment 34'. As already noted, however, flow through path 48 could result in inadvertent drying out of the bearing 22', if it is not effectively neutralized during pumping service of the blower 10' when there is no leakage of gas-air mixture into the compartment 34' requiring removal.During this interval of pumping service, there is therefore provided in accordance with the present invention a second passageway 50 in communication with the atmosphere, as at 52, and at its opposite end connected, as at 54, to the compartment 34' so as to induce an inflowing flow path 56 of air in response to the suction pressure being applied through the passageway 40 to the compartment 34'.

To summarize the improvements in the operational mode of the blower 10', let it be assumed that impeller 28' is being driven in rotation 58, and thus is effective in urging in movement a combustible gas-air mixture through inlet 12', through the impeller chamber 14', and out to a point of use through the blower outlet 16. During this pumping. interval of the blower 10' it will be further assumed that the seal 30' is effective in preventing any leakage of the combustible gas-air mixture into the compartment 34'.The suction pressure nevertheless being applied through the passageway 40 on the compartment 34' does not cause any drying out of the bearing 22' since at, this time it induces air to flow along path 56 into compartment 34' and thus by-passes the bearing 22', rather than flowing through it, to thereby establish communication at the opening 44 of the passageway 40 with the exiting path48 leadiny into the inlet of the impeller chamber 14'. In this manner, and specifically in avoiding air flow through the bearing 22', there is no tendency to force the oil or grease, in which the bearing 22 is packed, from leaving the bearing and thus failing to i)crforn its function (f facilitatiny rotation of the motor shaft 20'.

If it is next assumed, however, that prolonged pumping service of the blower 10' results in inadvertent wearing of the seal 30', it can then be expected that there will be some leakage of gas-air mixture rearwardly along the shaft 20' past the seal 32' initially established by the seal 30'. The combustible gas-air mixture which is collected in compartment 34', however, will be understood to be at a pressure which is greater than atmospheric pressure. In practice, and as a rule of thumb, the gas-air mixture which leaks into the compartment 34' is typically higher than atmospheric pressure. This s-air mixture at the pressure noted, is induced to return to the inlet of the impeller chamber 14' by the suction applied through the passageway 40.In this connection, it has been found in practice that optimum results are obtained when passageway 40 is of a diameter in the range of between 3/32 ins (2.3Smm) to 5/32 ins 3.97mm.

More particularly, the diameter selected for the passageway 40 is a function of blower capacity and back pressure, and should be sized so as to maintain a negative pressure in chamber 34' even when the blower discharge is restricted to near complete closure.

Reference should now be made to a second embodiment according to the present invention illustrated in FIG. 2C, in which there are many of the same structural features already described in connection with FIG. 2B and which, for brevity's sake, are therefore designated with the same but double-primed reference numerals, and will not be further referred to.The flajor difference between the embodiment of FIG. 2C as compared with that of FIG. 2B is that the motor 18" is not hermetically sealed in a housing 26", but is open to atmosphere through external openings 62 which, in turn, communicate via openings 64 to provide the same conmunicati)n between the atmosphere and the con'partmcI't. behind the bearing 22 for iicoming air that was the ftulction of passageway 50 of the embodiment of FIG. 263. Thus, in the blower embodiment of 1G. 2C, prior to a breakdown of the seal 30", the suction of the impeller chamber 14" is neutralized by atmospheric air flowiny into the compartment 34" along the path 66 and its establishing communication with the exiting flow out of the compartment 34" throuyh the passageway 40" to the inlet of the impeller chamber 14". In following the path 66, the bearing 22" is again effectively by-passed, and there is thus no tendency to cause any removal of any oil or any grease from the bearing 22".

However, should there be any breakdown in the seal 30", the suction applied to the compartment 34" will effectively remove any combustible gas-air mixture leaking into said compartment and return it to the inlet of the impeller chamber 14".

A latitude of modification, change, and substitution is intended in the foregoing disclosure and in some instances some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly anti in a manner consistent with the spirit and scope of the invention herein.

Claims (2)

WìiAT IS CLAIMED IS:

1. An improved blower for urying in movement a gaseous fluid from an inlet through an impeller chamber to an outlet of the type having a motor-driven shaft supported in a bearing, an impeller mounted on said shaft in said impeller chamber, and a seal operatively disposed in a normally sealing relation about said shaft in a location between said impeller and said bearing to correspondingly normally prevent any leakage of said gaseous fluid out of said impeller chamber rearwardly along said shaft, said blower improvements comprisiny a canpartment formed about said shaft bounded on one side by said seal and on an opposite side by said bearing for collecting any gaseous fluid leaking rearwardly along said shaft as a result of the weariny of said seal occurring during pumping service of said blower, a first passageway connected between said compartment and said inlet of said impeller chamber for establishing an exiting flow path under suction created by said impeller for any gaseous fluid entering into said compartment, and a second passageway connected from atmosphere to said compartment for establishing a normally inflowing flow path of air into said compartment past said ccmpartme nt-bound ing , bearing and having communication with said exiting flow path, whereby during blower pumping service whencver there is leakage w of gaseous fluid into said compartment said suction applied to said compartment draws air frexn atmosphere through said first.

passageway in a direction preventing the escape of said gaseous fluid to atmosphere and causes the removal thereof back to said impeller chamL)er.

2. An improved blower for a gaseous fluid as defined in Claim 1 including an impeller housing defining said impeller chamber having an external opening therein serving as the connection to atmosphere for said second passageway.