CA2227892A1 - Vacuum pressure seal - Google Patents
Vacuum pressure seal Download PDFInfo
- Publication number
- CA2227892A1 CA2227892A1 CA 2227892 CA2227892A CA2227892A1 CA 2227892 A1 CA2227892 A1 CA 2227892A1 CA 2227892 CA2227892 CA 2227892 CA 2227892 A CA2227892 A CA 2227892A CA 2227892 A1 CA2227892 A1 CA 2227892A1
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- impeller
- vacuum pressure
- inlet
- casing
- pressure chamber
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Abstract
A vacuum pressure seal for use with a centrifugal or axial gas exhaust fan. The seal comprises a vacuum pressure chamber covering the portion of the fan's casing through which the impeller shaft exits, and one or more tubes allow fluid communication between the vacuum pressure chamber and the inlet of the fan. The difference in gas pressure between the vacuum pressure chamber and the inlet of the fan caused by the operation of the fan results in leaked gas in the vacuum pressure chamber being drawn to the inlet.
Description
VACUUM PRESSURE SEAL
The present invention relates to gas exhaust fans and is primarily concerned with vacuum pressure seals adapted to prevent gas leakage from such fans.
It is common for centrifugal gas exhaust fans to allow gas to escape through the space between the casing of the fan and the impeller shaft. This is due in part to the fact that it is difficult to create an airtight seal between the stationary fan casing and the rotating shaft.
While the leakage of gas from a centrifugal gas exhaust fan is not always a concern, such fans are often used for the extraction from a certain area of noxious gases. Where such a fan is used to move noxious gases, it is important that leakage from the fan be minimized.
A number of devices have been designed to draw gas which has leaked out of the rear of a fan back to the inside of the fan. U. S. Patents 3,927,889 and 3,927,890, both issued to Maurice L. Adams, Jr. on December 23, 1975, disclose such a method. In these patents, the leaked gas is returned to the interior of the fan by means of an oil pump driven by a motor separate from the fan motor. Clearly, this design involves a certain expense as well as some design challenges involved in incorporating a pump and motor in the fan for such a task.
U. S. Patent 5,156,522, issued to Lynn P.
Tessier on October 20, l992, discloses another method of impeding the escape of gases through the rear of a centrifugal gas exhaust fan at the shaft. This method does not require the incorporation of any additional mechanical equipment as in the Adams patents. A tube is used to create a fluid connection between the outlet of the fan and the chamber at the rear of the fan into which gas leaks. When the fan is operating normally, the pressure of the gas at the outlet is higher than the pressure at the rear of the fan. The high-pressure outlet gas is, therefore, drawn into the tube towards the leaked gas in the chamber at the rear of the fan. The movement of the high-pressure gas encourages the leaked gas to return to the interior of the fan by retracing the path through which it leaked in the first place.
Unfortunately, according to the Tessier patent, such a method of encouraging gases into the interior of a fan can cause problems of gas turbulence when the fan is run at low speeds. The solution proposed by the Tessier patent involves the addition of a cup shaped shroud over the area through which the leaked gas is returned. This shroud deflects the gas returning to the interior of the fan along the radial direction of the impeller. The shroud is fixed to the impeller by a retaining nut.
Though less elaborate than the additions required by the Adams patents, this patent does call for the addition of parts to the interior of the fan.
It would be difficult to modify an existing centrifugal gas exhaust fan to accept the addition of the parts necessary to incorporate the improvements of either the Adams patents or the Tessier patent unless the fan had been originally designed with such a modification in mind.
Accordingly, there is a need for an improved vacuum pressure seal which avoids the disadvantages described above.
The invention comprises a vacuum pressure seal for attachment to the exterior of the rear of a fan casing through which passes the shaft of the fan. The vacuum pressure seal defines a vacuum pressure chamber which is placed so as to cover an existing conventional seal between the rear of the fan casing and the shaft.
The vacuum pressure chamber is placed in fluid communication with the inlet of the fan. The gas pressure in the vacuum pressure chamber is approximately equal to the gas pressure at the inlet of the fan.
Because of the action of the fan, which moves gas from the inlet through the interior near the impeller and then to the outlet, the gas pressure at the inlet is lower than that surrounding the impeller and the atmospheric pressure. The pressure difference between the vacuum pressure chamber at the rear of the fan and the inlet of the fan is such that exhaust gas which leaks from the fan casing into the vacuum pressure chamber is drawn from the chamber through the fluid communication means and into the inlet for re-circulation through the fan.
In accordance with the invention there is provided, in a gas exhaust fan comprising (i) an impeller, (ii) a shaft adapted to be attached to and to rotate the impeller, (iii) a casing adapted to surround the impeller and allow it to rotate, the casing having openings for fluid communication with an inlet and an outlet and to allow the impeller or its shaft to extend to the exterior of the casing, (iv) a conventional seal adapted for attachment to the casing and for rotating attachment to the impeller or the shaft, and (v) the inlet; the improvement comprising a vacuum pressure seal defining a vacuum pressure chamber and adapted for attachment to the conventional seal and for surrounding the impeller or the shaft, and means for fluid communication between the vacuum pressure chamber and the inlet.
An advantage of the present invention is that gas leakage from the fan is minimized.
Another advantage of the present invention is that it can be readily incorporated into an existing fan.
Another advantage of the present invention is that it can be incorporated without complex redesign of the fan and without the introduction of mechanical devices.
The invention will be better understood by way of the following detailed description of a preferred embodiment with reference to the appended drawings, in which:
Fig. 1 is a rear elevation of a centrifugal gas exhaust fan mounted on a base and having incorporated therewith a vacuum pressure seal and tubes in accordance with the preferred embodiment of the present invention;
Fig. 2 is an axial cross-sectional view of a centrifugal gas exhaust fan mounted on a base and having incorporated therewith a vacuum pressure seal and tubes in accordance with the preferred embodiment of the present invention taken along line 2-2 of Fig. 1;
Fig. 3 is an enlarged rear elevation of a vacuum pressure seal in accordance with the preferred embodiment of the present invention; and Fig. 4 is an axial, enlarged, fragmentary cross-sectional view of a vacuum pressure seal in accordance with the present invention taken along line 4 4 of Fig. 3, shown adjacent a centrifugal gas exhaust fan impeller having attached thereto a shaft.
Referring to Figs. 1 and 2, there is shown a centrifugal gas exhaust fan 10 having a casing 12 and defining an outlet 14 and an inlet 16. A rear fan support plate 18 is attached to the casing 12 by means of bolts 20.
Within the casing 12, the fan 10 comprises an impeller 22 having fixed thereto an impeller hub 24 which in turn is fixed to a shaft 26. The shaft 26, the impeller hub 24, and the impeller 22 are fixed to one another by means of a bolt 28.
The frame supporting the casing 12 of the fan 10 comprises a rear frame base element 34, a front frame base element 36, and side frame base elements 38. The basE~ elements support front frame supports 40 and rear frame supports 42a and 42b. A bearing support bracket 44 is mounted horizontally to the rear frame supports 42a and 42b. Bearing 32 is bolted to the bearing support brar_ket 44.
The fan casing 12 is further supported with the inlet 16 to the front frame supports 40 by means of bolts 46.
A vacuum pressure seal 50, in accordance with an embodiment of the present invention, is shown attached to the rear fan support plate 18 by means of bolts 52. A
vacuum pressure chamber 60 is shown surrounding the shaft 26. The vacuum pressure seal 50 comprises a rectangular plate 54, a circular plate 56, and a circumferential plate 58, a11 of which collectively define a vacuum pressure chamber 60. The rectangular plate 54 is shown mounted to the rear fan support plate 18 and has an opening for the impeller hub 24. An outer seal 61 is placed in between the rear fan support plate 18 and the rectangular plate 54 of the vacuum pressure seal 50. The circular plate 56 has an opening to accommodate the shaft 26. The openings in plates 54 and 56 have very close tolerances with the shaft 26 and hub 24 in order to minimize the air leakage into the pressure seal 50. The circumferential plate 58 seals the vacuum pressure chamber 60 by joining the rectangular plate 54 and the circular plate 56.
A pair of tubes 62a and 62b are connected at one end to spigots 64a and 64b on circumferential plate 58. The other end of each tube 62a and 62b is fixed to the inlet 16 by means of a spigot 66. The tubes 62a, 62b are preferably made of PVC but can be of any suitable material. These tubes 62a, 62b allow fluid communication between the vacuum pressure chamber 60 and the inlet 16.
The present invention relates to gas exhaust fans and is primarily concerned with vacuum pressure seals adapted to prevent gas leakage from such fans.
It is common for centrifugal gas exhaust fans to allow gas to escape through the space between the casing of the fan and the impeller shaft. This is due in part to the fact that it is difficult to create an airtight seal between the stationary fan casing and the rotating shaft.
While the leakage of gas from a centrifugal gas exhaust fan is not always a concern, such fans are often used for the extraction from a certain area of noxious gases. Where such a fan is used to move noxious gases, it is important that leakage from the fan be minimized.
A number of devices have been designed to draw gas which has leaked out of the rear of a fan back to the inside of the fan. U. S. Patents 3,927,889 and 3,927,890, both issued to Maurice L. Adams, Jr. on December 23, 1975, disclose such a method. In these patents, the leaked gas is returned to the interior of the fan by means of an oil pump driven by a motor separate from the fan motor. Clearly, this design involves a certain expense as well as some design challenges involved in incorporating a pump and motor in the fan for such a task.
U. S. Patent 5,156,522, issued to Lynn P.
Tessier on October 20, l992, discloses another method of impeding the escape of gases through the rear of a centrifugal gas exhaust fan at the shaft. This method does not require the incorporation of any additional mechanical equipment as in the Adams patents. A tube is used to create a fluid connection between the outlet of the fan and the chamber at the rear of the fan into which gas leaks. When the fan is operating normally, the pressure of the gas at the outlet is higher than the pressure at the rear of the fan. The high-pressure outlet gas is, therefore, drawn into the tube towards the leaked gas in the chamber at the rear of the fan. The movement of the high-pressure gas encourages the leaked gas to return to the interior of the fan by retracing the path through which it leaked in the first place.
Unfortunately, according to the Tessier patent, such a method of encouraging gases into the interior of a fan can cause problems of gas turbulence when the fan is run at low speeds. The solution proposed by the Tessier patent involves the addition of a cup shaped shroud over the area through which the leaked gas is returned. This shroud deflects the gas returning to the interior of the fan along the radial direction of the impeller. The shroud is fixed to the impeller by a retaining nut.
Though less elaborate than the additions required by the Adams patents, this patent does call for the addition of parts to the interior of the fan.
It would be difficult to modify an existing centrifugal gas exhaust fan to accept the addition of the parts necessary to incorporate the improvements of either the Adams patents or the Tessier patent unless the fan had been originally designed with such a modification in mind.
Accordingly, there is a need for an improved vacuum pressure seal which avoids the disadvantages described above.
The invention comprises a vacuum pressure seal for attachment to the exterior of the rear of a fan casing through which passes the shaft of the fan. The vacuum pressure seal defines a vacuum pressure chamber which is placed so as to cover an existing conventional seal between the rear of the fan casing and the shaft.
The vacuum pressure chamber is placed in fluid communication with the inlet of the fan. The gas pressure in the vacuum pressure chamber is approximately equal to the gas pressure at the inlet of the fan.
Because of the action of the fan, which moves gas from the inlet through the interior near the impeller and then to the outlet, the gas pressure at the inlet is lower than that surrounding the impeller and the atmospheric pressure. The pressure difference between the vacuum pressure chamber at the rear of the fan and the inlet of the fan is such that exhaust gas which leaks from the fan casing into the vacuum pressure chamber is drawn from the chamber through the fluid communication means and into the inlet for re-circulation through the fan.
In accordance with the invention there is provided, in a gas exhaust fan comprising (i) an impeller, (ii) a shaft adapted to be attached to and to rotate the impeller, (iii) a casing adapted to surround the impeller and allow it to rotate, the casing having openings for fluid communication with an inlet and an outlet and to allow the impeller or its shaft to extend to the exterior of the casing, (iv) a conventional seal adapted for attachment to the casing and for rotating attachment to the impeller or the shaft, and (v) the inlet; the improvement comprising a vacuum pressure seal defining a vacuum pressure chamber and adapted for attachment to the conventional seal and for surrounding the impeller or the shaft, and means for fluid communication between the vacuum pressure chamber and the inlet.
An advantage of the present invention is that gas leakage from the fan is minimized.
Another advantage of the present invention is that it can be readily incorporated into an existing fan.
Another advantage of the present invention is that it can be incorporated without complex redesign of the fan and without the introduction of mechanical devices.
The invention will be better understood by way of the following detailed description of a preferred embodiment with reference to the appended drawings, in which:
Fig. 1 is a rear elevation of a centrifugal gas exhaust fan mounted on a base and having incorporated therewith a vacuum pressure seal and tubes in accordance with the preferred embodiment of the present invention;
Fig. 2 is an axial cross-sectional view of a centrifugal gas exhaust fan mounted on a base and having incorporated therewith a vacuum pressure seal and tubes in accordance with the preferred embodiment of the present invention taken along line 2-2 of Fig. 1;
Fig. 3 is an enlarged rear elevation of a vacuum pressure seal in accordance with the preferred embodiment of the present invention; and Fig. 4 is an axial, enlarged, fragmentary cross-sectional view of a vacuum pressure seal in accordance with the present invention taken along line 4 4 of Fig. 3, shown adjacent a centrifugal gas exhaust fan impeller having attached thereto a shaft.
Referring to Figs. 1 and 2, there is shown a centrifugal gas exhaust fan 10 having a casing 12 and defining an outlet 14 and an inlet 16. A rear fan support plate 18 is attached to the casing 12 by means of bolts 20.
Within the casing 12, the fan 10 comprises an impeller 22 having fixed thereto an impeller hub 24 which in turn is fixed to a shaft 26. The shaft 26, the impeller hub 24, and the impeller 22 are fixed to one another by means of a bolt 28.
The frame supporting the casing 12 of the fan 10 comprises a rear frame base element 34, a front frame base element 36, and side frame base elements 38. The basE~ elements support front frame supports 40 and rear frame supports 42a and 42b. A bearing support bracket 44 is mounted horizontally to the rear frame supports 42a and 42b. Bearing 32 is bolted to the bearing support brar_ket 44.
The fan casing 12 is further supported with the inlet 16 to the front frame supports 40 by means of bolts 46.
A vacuum pressure seal 50, in accordance with an embodiment of the present invention, is shown attached to the rear fan support plate 18 by means of bolts 52. A
vacuum pressure chamber 60 is shown surrounding the shaft 26. The vacuum pressure seal 50 comprises a rectangular plate 54, a circular plate 56, and a circumferential plate 58, a11 of which collectively define a vacuum pressure chamber 60. The rectangular plate 54 is shown mounted to the rear fan support plate 18 and has an opening for the impeller hub 24. An outer seal 61 is placed in between the rear fan support plate 18 and the rectangular plate 54 of the vacuum pressure seal 50. The circular plate 56 has an opening to accommodate the shaft 26. The openings in plates 54 and 56 have very close tolerances with the shaft 26 and hub 24 in order to minimize the air leakage into the pressure seal 50. The circumferential plate 58 seals the vacuum pressure chamber 60 by joining the rectangular plate 54 and the circular plate 56.
A pair of tubes 62a and 62b are connected at one end to spigots 64a and 64b on circumferential plate 58. The other end of each tube 62a and 62b is fixed to the inlet 16 by means of a spigot 66. The tubes 62a, 62b are preferably made of PVC but can be of any suitable material. These tubes 62a, 62b allow fluid communication between the vacuum pressure chamber 60 and the inlet 16.
Though Fig. 1 shows two tubes, the number of such tubes could be one or more without departing from the scope of the present invention.
Fig. 3 shows the vacuum pressure seal 50 enlarged and before it is mounted to the casing 12, including a rectangular front plate 54 and a circular rear_ plate 56. The rectangular plate 54 includes holes 68 for passage of bolts 52 for mounting the vacuum pressure seal 50 on a centrifugal gas exhaust fan. Both the rectangular plate 54 and the circular plate 56 also include aligned openings 70 for passage of the shaft 26.
Though the openings 70 are shown as being the same diameter, they could be a different size in the case where the impeller hub 24 extends past the rectangular plate 54 when it is mounted as shown in Fig. 2. Also shown in Fig. 3 are spigots 64a, 64b including ribbed portions 72 for secure attachment of tubes 62a and 62b respectively.
Referring now to Fig. 4, there is shown the vacuum pressure seal 50 taken along line 4-4 of Fig. 3 and mounted to a plate 74 which in turn is mounted to the casing 12. Between the plate 74 and the casing 12, there is shown the seal 21 and the mounting plate 18. Arrows indicate the direction of flow of gas leaking from the rear- of the fan when the vacuum pressure seal 50 is operational. The arrows also indicate the path of the gases from the vacuum pressure chamber 60 through spigots 64a and the tubes 62a.
When the centrifugal gas exhaust fan 10 is in operation, the impeller 22 pumps gases from the inlet 16 and through the outlet 14. Because of the funnel shape of the inlet 16, the speed of the air passing through the inlet 16 increases with increasing proximity to the impeller 22. Another effect of the shape of the inlet 16 is 'that the static pressure of the gas therein at the pos_Ltion of the spigot 66 is relatively low as compared to i:he gas pressure adjacent the impeller 22.
Since the gas which leaks from the rear of the fan is at approximately the pressure of the gas adj acent to the impeller 22, the gas pressure in the vacuum pressure chamber 60 is higher than the gas pressure at the spigot 66 in the inlet 16 at the position of spigot 66 whenever the fan is in operation. Therefore, when the tube 62a or 62b is connected to the vacuum pressure chamber 60 and to the inlet 16, allowing fluid communication between the two, gas in the vacuum pressure chamber 60 tends to be drawn through the tube 62 to the inlet 16.
In order to control the flow of gas through the tubE~ 62, a conventional regulating valve (not shown) may be added at some point thereon.
It should be understood that the configuration of the centrifugal gas exhaust fan 10 and the vacuum pressure seal 50 could be varied without departing from the scope of the invention.
For example, the impeller hub 24 attached to the impeller 22 may extend to the exterior of the casing 12 of the fan 10, as shown in Fig. 2. In such a case, any conventional seals used to inhibit the path of the leakage of gas from the interior of the fan would be attached to the casing 12 and in rotating relation with the impeller hub 24. However, another arrangement is shown in Fig. 4, whereby the shaft 26 extends through the opening in the rear of the fan and the impeller hub 24 does not extend to the exterior of the fan. In this case, any conventional seals which are similarly attached to the casing 12 should be in rotating relation with the shaft 26.
A similar variation is possible in respect of the vacuum pressure chamber 60, wherein the impeller hub 24 may be arranged such that it extends to the exterior of the rear of the fan but does not extend to the exterior of the vacuum pressure chamber 60, all as shown in Fig. 2. Another possible arrangement would involve the impeller hub 24 extending beyond the plate 56 of the vacuum pressure chamber 60. Such an embodiment could be employed without departing from the scope of the invention.
It should also be understood that the configuration of the inlet 16 need not involve a portion thereof having a gradually reduced cross-section with increasing proximity to the impeller 22, as shown in Fig.
2. The gas static pressure in the inlet 16 during operation of the fan would remain below the gas pressure adjacent the impeller 22 and therefore in the vacuum pre:>sure chamber 60 even without this feature, albeit the pressure difference would be reduced.
In addition, it should be understood that either the inner seal 30 or the outer seal 61 or both could be omitted from the fan without departing from the scope of the present invention. However, in order for the vacuum pressure seal described herein to operate efficiently, it is preferable that there be some conventional seal between the fan casing 12 and either the shaft 26 or the impeller hub 24, as the case may be, to reduce the amount of leaked gas with which the vacuum pre:~sure chamber 60 is required to deal.
It should also be understood that the front plate 54 of the vacuum pressure seal 50 may have a shape other than rectangular without departing from the scope of the invention. Similarly, the rear plate 56 of the vacuum pressure seal 50 may have a shape other than circular without departing from the scope of the invention.
Fig. 3 shows the vacuum pressure seal 50 enlarged and before it is mounted to the casing 12, including a rectangular front plate 54 and a circular rear_ plate 56. The rectangular plate 54 includes holes 68 for passage of bolts 52 for mounting the vacuum pressure seal 50 on a centrifugal gas exhaust fan. Both the rectangular plate 54 and the circular plate 56 also include aligned openings 70 for passage of the shaft 26.
Though the openings 70 are shown as being the same diameter, they could be a different size in the case where the impeller hub 24 extends past the rectangular plate 54 when it is mounted as shown in Fig. 2. Also shown in Fig. 3 are spigots 64a, 64b including ribbed portions 72 for secure attachment of tubes 62a and 62b respectively.
Referring now to Fig. 4, there is shown the vacuum pressure seal 50 taken along line 4-4 of Fig. 3 and mounted to a plate 74 which in turn is mounted to the casing 12. Between the plate 74 and the casing 12, there is shown the seal 21 and the mounting plate 18. Arrows indicate the direction of flow of gas leaking from the rear- of the fan when the vacuum pressure seal 50 is operational. The arrows also indicate the path of the gases from the vacuum pressure chamber 60 through spigots 64a and the tubes 62a.
When the centrifugal gas exhaust fan 10 is in operation, the impeller 22 pumps gases from the inlet 16 and through the outlet 14. Because of the funnel shape of the inlet 16, the speed of the air passing through the inlet 16 increases with increasing proximity to the impeller 22. Another effect of the shape of the inlet 16 is 'that the static pressure of the gas therein at the pos_Ltion of the spigot 66 is relatively low as compared to i:he gas pressure adjacent the impeller 22.
Since the gas which leaks from the rear of the fan is at approximately the pressure of the gas adj acent to the impeller 22, the gas pressure in the vacuum pressure chamber 60 is higher than the gas pressure at the spigot 66 in the inlet 16 at the position of spigot 66 whenever the fan is in operation. Therefore, when the tube 62a or 62b is connected to the vacuum pressure chamber 60 and to the inlet 16, allowing fluid communication between the two, gas in the vacuum pressure chamber 60 tends to be drawn through the tube 62 to the inlet 16.
In order to control the flow of gas through the tubE~ 62, a conventional regulating valve (not shown) may be added at some point thereon.
It should be understood that the configuration of the centrifugal gas exhaust fan 10 and the vacuum pressure seal 50 could be varied without departing from the scope of the invention.
For example, the impeller hub 24 attached to the impeller 22 may extend to the exterior of the casing 12 of the fan 10, as shown in Fig. 2. In such a case, any conventional seals used to inhibit the path of the leakage of gas from the interior of the fan would be attached to the casing 12 and in rotating relation with the impeller hub 24. However, another arrangement is shown in Fig. 4, whereby the shaft 26 extends through the opening in the rear of the fan and the impeller hub 24 does not extend to the exterior of the fan. In this case, any conventional seals which are similarly attached to the casing 12 should be in rotating relation with the shaft 26.
A similar variation is possible in respect of the vacuum pressure chamber 60, wherein the impeller hub 24 may be arranged such that it extends to the exterior of the rear of the fan but does not extend to the exterior of the vacuum pressure chamber 60, all as shown in Fig. 2. Another possible arrangement would involve the impeller hub 24 extending beyond the plate 56 of the vacuum pressure chamber 60. Such an embodiment could be employed without departing from the scope of the invention.
It should also be understood that the configuration of the inlet 16 need not involve a portion thereof having a gradually reduced cross-section with increasing proximity to the impeller 22, as shown in Fig.
2. The gas static pressure in the inlet 16 during operation of the fan would remain below the gas pressure adjacent the impeller 22 and therefore in the vacuum pre:>sure chamber 60 even without this feature, albeit the pressure difference would be reduced.
In addition, it should be understood that either the inner seal 30 or the outer seal 61 or both could be omitted from the fan without departing from the scope of the present invention. However, in order for the vacuum pressure seal described herein to operate efficiently, it is preferable that there be some conventional seal between the fan casing 12 and either the shaft 26 or the impeller hub 24, as the case may be, to reduce the amount of leaked gas with which the vacuum pre:~sure chamber 60 is required to deal.
It should also be understood that the front plate 54 of the vacuum pressure seal 50 may have a shape other than rectangular without departing from the scope of the invention. Similarly, the rear plate 56 of the vacuum pressure seal 50 may have a shape other than circular without departing from the scope of the invention.
Claims (13)
1. In a gas exhaust fan comprising:
an impeller;
a rotating shaft for mounting said impeller;
a casing adapted to surround said impeller and allow it to rotate, said casing having openings for fluid conununication with an inlet and an outlet and an opening to pass at least said shaft to extend to the exterior of said casing;
the improvement comprising a vacuum pressure seal defining a vacuum pressure chamber and adapted for attachment to said casing and for surrounding at least said shaft, and means for fluid communication between said vacuum pressure chamber and said inlet.
an impeller;
a rotating shaft for mounting said impeller;
a casing adapted to surround said impeller and allow it to rotate, said casing having openings for fluid conununication with an inlet and an outlet and an opening to pass at least said shaft to extend to the exterior of said casing;
the improvement comprising a vacuum pressure seal defining a vacuum pressure chamber and adapted for attachment to said casing and for surrounding at least said shaft, and means for fluid communication between said vacuum pressure chamber and said inlet.
2. The gas exhaust fan improvements defined in claim 1, wherein said impeller includes an impeller hub.
3. The gas exhaust fan improvements defined in claim 1, wherein said means for fluid communication between said vacuum pressure chamber and said inlet comprises at least one tube adapted for attachment at one end to said vacuum pressure chamber and at another end to said inlet.
4. The gas exhaust fan improvements defined in clam 3, wherein at least one regulating valve is adapted for attachment to a portion of said at least one tube.
5. The gas exhaust fan improvements defined in claim 3, wherein said at least one tube is adapted for attachment to and fluid communication with said inlet at least at a first position thereon, and said inlet has a cross-sectional area at said first position thereon which is greater than its cross-sectional area at a second position thereon located adjacent said impeller.
6. In a gas exhaust fan comprising:
an impeller, including an impeller hub;
a shaft adapted to be attached to and to rotate said impeller;
a casing adapted to surround said impeller and allow it to rotate, said casing having openings for fluid communication with an inlet and an outlet and to allow at least one of said impeller and said shaft to extend to the exterior of said casing;
a seal adapted for attachment to said casing and for accommodating one of said impeller and said shaft;
the improvement comprising a vacuum pressure seal defining a vacuum pressure chamber and adapted for attachment to at least one of said seal and said casing and for allowing rotation of at least one of said impeller and said shaft, and means for fluid communication between said vacuum pressure chamber and said inlet.
an impeller, including an impeller hub;
a shaft adapted to be attached to and to rotate said impeller;
a casing adapted to surround said impeller and allow it to rotate, said casing having openings for fluid communication with an inlet and an outlet and to allow at least one of said impeller and said shaft to extend to the exterior of said casing;
a seal adapted for attachment to said casing and for accommodating one of said impeller and said shaft;
the improvement comprising a vacuum pressure seal defining a vacuum pressure chamber and adapted for attachment to at least one of said seal and said casing and for allowing rotation of at least one of said impeller and said shaft, and means for fluid communication between said vacuum pressure chamber and said inlet.
7. The gas exhaust fan improvements defined in claim 6, wherein said means for fluid communication between said vacuum pressure chamber and said inlet comprises at least one tube adapted for attachment at one end to said vacuum pressure chamber and at another end to said inlet.
8. The gas exhaust fan improvements defined in claim 7, wherein at least one regulating valve is adapted for attachment to a portion of said at least one tube.
9. The gas exhaust fan improvements defined in claim 7, wherein said at least one tube is adapted for attachment to and fluid communication with said inlet at least at a first position thereon, and said inlet has a cross-sectional area at said first position thereon which is greater than its cross-sectional area at a second position thereon located adjacent said impeller.
10. In a gas exhaust fan comprising:
an impeller, including an impeller hub;
a shaft adapted to be attached to and to rotate said impeller;
a casing adapted to surround said impeller and allow it to rotate, said casing having openings for fluid communication with an inlet and an outlet and to allow at least one of said impeller and said shaft to extend to the exterior of said casing;
a seal adapted for attachment to said casing and for rotating attachment to one of said impeller and said shaft;
the improvement comprising said seal including a vacuum pressure chamber adapted for attachment to said casing and for accommodating at least one of said impeller hub and said shaft, and means for fluid communication between said vacuum pressure chamber and said inlet.
an impeller, including an impeller hub;
a shaft adapted to be attached to and to rotate said impeller;
a casing adapted to surround said impeller and allow it to rotate, said casing having openings for fluid communication with an inlet and an outlet and to allow at least one of said impeller and said shaft to extend to the exterior of said casing;
a seal adapted for attachment to said casing and for rotating attachment to one of said impeller and said shaft;
the improvement comprising said seal including a vacuum pressure chamber adapted for attachment to said casing and for accommodating at least one of said impeller hub and said shaft, and means for fluid communication between said vacuum pressure chamber and said inlet.
11. The gas exhaust fan improvements defined in claim 10, wherein said means for fluid communication between said vacuum pressure chamber and said inlet comprises at least one tube adapted for attachment at one end to said vacuum pressure chamber and at another end to said inlet.
12. The gas exhaust fan improvements defined in claim 11, wherein at least one regulating valve is adapted for attachment to a portion of said at least one tube.
13. The gas exhaust fan improvements defined in claim 11, wherein said at least one tube is adapted for attachment to and fluid communication with said inlet at least at a first position thereon, and said inlet has a cross-sectional area at said first position thereon which is greater than its cross-sectional area at a second position thereon located adjacent said impeller.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US406498A | 1998-01-08 | 1998-01-08 | |
| US09/004,064 | 1998-01-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2227892A1 true CA2227892A1 (en) | 1999-07-08 |
Family
ID=29418018
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2227892 Abandoned CA2227892A1 (en) | 1998-01-08 | 1998-01-26 | Vacuum pressure seal |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2227892A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102251976A (en) * | 2011-08-04 | 2011-11-23 | 张家港施亿百机电设备有限公司 | Small centrifugal fan |
-
1998
- 1998-01-26 CA CA 2227892 patent/CA2227892A1/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102251976A (en) * | 2011-08-04 | 2011-11-23 | 张家港施亿百机电设备有限公司 | Small centrifugal fan |
| CN102251976B (en) * | 2011-08-04 | 2013-01-16 | 张家港施亿百机电设备有限公司 | Small centrifugal fan |
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| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |