Reduced noise diffuser for a motor-fan assembly
An air diffuser for a motor-fan unit having reduced blade passage frequencies, and reduced noise generation, includes a baffle plate, external vanes, internal vanes, diffuser ports, and a central opening. The baffle plate of the diffuser is made integral with the internal and external vanes, such that any leaking, rattling, or pure tone noise that may be generated from air movement over the surface of the diffuser are prevented or reduced. Additionally, the number of internal and external vanes provided by the diffuser is that equal to a prime number, thus resulting in a reduction of harmonic and pure tone noise generated during the operation of the motor-fan unit.
The present invention generally relates to diffusers used in association with various motor-fan systems. More particularly, the present invention relates to an air diffuser that reduces vane passage frequencies, and associated noise, which is generated from air movement over the surface of the diffuser. Specifically, the present invention is directed to a noise reducing diffuser that operatively secures the brushes of an electric motor. More specifically, the present invention relates to a noise reducing diffuser that is interchangeable with existing diffusers installed in various motor-fan units.
BACKGROUND OF THE INVENTIONElectric motors are well known in the art and have been put to use in a variety of applications, including the handling of air. In this circumstance, an electric motor is coupled to a fan, creating a motor-fan unit, which produces an airflow as needed. When providing air movement, the motor-fan unit may supply cooling air to the motor, so as to maintain the motor's operating temperature at an optimal level, allowing the motor's operating life to be extended. The motor-fan unit may also be used to generate working air for vacuum type devices.
To achieve this effect, the fan is mounted on a motor driven shaft, which draws air into a fan shroud. The fan shroud compresses or pressurizes the incoming air, which is resultantly released into the motor housing via one or more ports in a diffuser plate, causing the air to be directed toward the motor windings. As a result, the heat from the motor is drawn into the airflow and exhausted from the motor housing, thus enhancing the motor's operating life.
Many diffusers used with motor-fan units, incorporate radial turning vanes with a separately attached baffle plate to move the pressurized air from the fan shroud to the motor assembly. However, the baffle plates of these diffusers are not made integral with the turning vanes. This results in a baffle plate that does not form a complete seal with the attached turning vanes. Because of this inadequate or compromised seal, the diffuser generates leaking, rattling, and pure tone noises as the motor-fan unit draws air through the diffuser. In addition, blade passage frequencies are also created as air is passed over the diffuser's vanes. As such, many motor-fan units are uncomfortably noisy to many users. Further, the use of such motor-fan units may be limited to those applications where such noise can be tolerated.
In addition to the diffuser portion of the motor-fan unit, the motor itself comprises field windings that surround an armature that is centrally located on a shaft, which is rotatably mounted on suitable bearings. A commutator is also mounted on the shaft and placed in electrical contact with a power supply by a pair of opposed brushes contacting the commutator. Typically, these brushes and/or armature are completely or partially closed off from the cooling air provided by the fan unit. As such, the motor's efficiency and operating life are reduced due to the heat generated by the motor.
Therefore, there is a need for a diffuser for a motor-fan unit with radial turning vanes that has an integrated baffle plate to provide reduced noise during the motor-fan unit's operation. Additionally, there is a need for a reduced noise diffuser that allows cooling air to pass to the brushes and/or armature of the motor while supporting the brushes of the motor. Further, there is a need for an interchangeable diffuser with reduced vane passage frequencies, and reduced noise generation that can be used in association with existing motor-fan assemblies, while providing suitable cooling for the motor's armature and/or brushes.
DISCLOSURE OF INVENTIONIn light of the foregoing, it is a first aspect of the present invention to provide a reduced noise diffuser for a motor-fan assembly.
It is another aspect of the present invention to provide a diffuser interposed between a shrouded fan assembly and a motor assembly having a shaft that rotates a fan carried within the shrouded fan assembly, the diffuser comprising a baffle plate having a motor side and a fan side, the baffle plate having an opening therethrough; and a plurality of vanes extending from the motor side, each vane having an external portion which radially extends from the baffle plate, wherein adjacent vanes have a port therebetween, the plurality of vanes directing air flow generated by the fan from the fan side through the ports to the motor side.
It is yet another aspect of the present invention to provide a motor-fan assembly comprising a field winding; an armature having a shaft, the armature rotatably mounted within the field winding; a fan attached to the shaft; and a diffuser interposed between the fan and the field winding, the diffuser comprising a baffle plate having a motor side and a fan side; the baffle plate having an opening therethrough; a plurality of vanes extending from the motor side; each vane having an external portion which radially extends from the baffle plate wherein adjacent vanes have a port therebetween; and the plurality of vanes directing airflow generated by the fan from the fan side through the ports to the motor side.
DESCRIPTION OF THE DRAWINGSThese and other features and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where:
A motor-fan unit, indicated generally by the numeral 10 in the accompanying
As shown in
The motor assembly 12 is provided with an end plate assembly which is generally indicated by the numeral 42 shown in
Because the brushes 22 make electrical contact with the commutator 20 during the operation of the motor-fan unit 10, a pair of brush retainers generally indicated by the 5 numeral 62 are provided by the end plate assembly 42. The structure of each brush retainer 62 is largely identical to the other, with one brush retainer 62 being a mirror image of the other. Therefore, the following discussion will describe only a single brush retainer 62. As shown in
As shown in
Continuing with the brush retainer 62 as shown in
To ensure contact between the brush 22 and the commutator 20 of the motor 16, the brush 22 is biased into engagement with the commutator 20, as shown in
While spring retainer projection 94 may comprise a wall, an L-shaped projection may be used as shown in
As shown in
Air drawn into the shroud 34 by the fan assembly 14, is directed to the motor 16 by a diffuser assembly that is designated generally by the numeral 120. The diffuser assembly 120 is interposed between the fan 28 and the end plate assembly 42 and is configured to be interchangeable with existing diffuser assemblies that are part of other motor-fan units 10. That is, the diffuser assembly 120 of the present invention is designed to cooperate with end plate assemblies 42 of varying motor-fan units 10 so that the brushes 22 of such unit 10 are sufficiently supported. As shown in
The curvilinear vanes 128 may comprise radial turning vanes, wherein the number of vanes is equal to that of a prime number. It is believed that by having such an arrangement, the diffuser assembly 120 is able to reduce the harmonic interaction between the fan 14 and the diffuser at certain revolutions-per-minute multiples as the fan assembly 14 rotates. In general, many harmonics may be generated by air passing by over the surface of the diffuser vanes. For example, in arrangements where a diffuser utilizes a number of vanes not equal to a prime number, generated harmonics may occur at multiples of the smallest mathematical factor for the number of vanes present. In contrast, a diffuser having a number of vanes equal to that of a prime number only has two factors (i.e. the number 1 and the prime number itself). As such, the use of the diffuser 128 with a number of vanes equal to that of a prime number eliminates the factor harmonics that would otherwise be created by a diffuser with a number of vanes not equal to a prime number.
When the unit 10 is assembled and the motor assembly 12 rotates the fan assembly 14, air is drawn in through the shroud intake 34 and into the fan assembly 14. The fan assembly 14 exhausts the air radially such that it swirls around within the interior of the shroud and is redirected by the baffle plate 122 and, in particular, the curvilinear vanes 128. The air is guided through the ports 134 and swirls about the collection chamber 138 so that the air is forced radially inwardly toward the central opening 126 where it is then redirected so as to flow through the cavities 104 and other regions of the end plate assembly 42. Accordingly, the air drawn in through the shroud intake 136 is directed through the motor assembly 12 as needed for the end application.
Specifically, the vanes 128 may comprise radial turning vanes and/or may be equal in number to that of a prime number. For example, the number of turning vanes 128 may total 23, 29, or 37, although any other suitable prime number of turning vanes 128 may be utilized. By having such an arrangement, the diffuser assembly 120 is able to reduce the harmonic interaction between the fan 14 and the diffuser 120 at certain rpm multiples as the motor-fan unit 10 is in operation. More specifically, as high velocity air departs from a vane the resulting airflow also includes a vortex component that shears against other nearby vanes resulting in noise. The generated noise has its largest magnitude at frequencies equal to the multiples of the fan revolutions per minute (rpm) and the number of diffuser vanes. Thus, by altering the number of vanes 128 and/or the rpm of the fan 28 of the motor-fan unit 10, the noise frequencies with higher magnitudes may be shifted to different frequencies, thus minimizing the noise that would otherwise occur. As such, the noise generated by air passing through the diffuser 120 is thereby reduced.
Additionally as shown in
As shown in
Upstanding members 142 and 144 are of a suitable height to the internal curvilinear vanes 128 to allow for proper attachment of the diffuser assembly 120 to the end plate assembly 42. Further, upstanding members 142,144 may extend sufficiently beyond the height of the vanes 128 to an extent, such that they extend into the open mouths 72 defined by brush retainers 62. As a result the diffuser 120 is capable of attachment to the end plate assembly 42. Upstanding member 142 may have a raised edge 148 sized to fill the gap or notch 78 between the plate portion 44 and member 68 of the brush retainer 62. In this way, the brush cap assembly 139 encloses the brushes 22 when the end plate 42 and diffuser 120 are coupled to one another. Adjacent the raised edge 148, upstanding member 142 may be provided with a landing 150, which has the same height as upstanding member 144, thereby forming a recessed area that lies adjacent to the brush 22 when the diffuser assembly 120 and end plate assembly 42 are joined. The channel 140, opens toward the motor assembly 12 between the landing 150 and upstanding member 144. This arrangement, allows air generated by the fan assembly 14 to be distributed across the exposed surface 152 of the brush 22 that lies adjacent the brush cap assemblies 139 shown in
An alternative embodiment of the brush cap assemblies 139 are shown in
As shown in
It will, therefore, be appreciated that one advantage of one or more embodiments of the present invention is that the noise and vane passage frequencies associated with air movement over the diffuser's vanes are reduced. Still another advantage of the present invention is that the diffuser plate is configured, such that, the diffuser is capable of replacing a previously installed diffuser of an existing motor-fan unit. Yet another advantages of the present invention is that the diffuser is able to support the brushes of the motor-fan unit without additional adjustment to the diffuser.
Although the present invention has been described in considerable detail with reference to certain embodiments, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein.
Claims
1. A diffuser interposed between a shrouded fan assembly and a motor assembly having a shaft that rotates a fan carried within said shrouded fan assembly, the diffuser comprising:
- a baffle plate having a motor side and a fan side, said baffle plate having an opening therethrough; and
- a plurality of vanes extending from said motor side, each said vane having an external portion which radially extends from said baffle plate, wherein adjacent vanes have a port therebetween, said plurality of vanes directing airflow generated by the fan from said fan side through said ports to said motor side.
2. The diffuser according to claim 1, wherein each said vane has an internal portion contiguous with said external portion, said internal portions extending toward said opening.
3. The diffuser according to claim 2, wherein said vanes are curvilinear and spaced apart from each other.
4. The diffuser according to claim 2, wherein said internal portions terminate prior to reaching said opening so as to collectively form a collection chamber for the airflow.
5. The diffuser according to claim 1, wherein each said vane has a plate edge at said motor side and ring edge opposite said plate edge.
6. The diffuser according to claim 5, further comprising:
- a vane support ring connected to at least some of said vanes.
7. The diffuser according to claim 6, wherein said vane support ring is connected to at least some of said ring edges, said vane support ring having an inner edge with a diameter at least equal to or larger than said baffle plate's diameter.
8. The diffuser according to claim 1, wherein each said vane comprises a radial turning vane.
9. The diffuser according to claim 1, wherein said baffle plate is annular.
10. The diffuser according to claim 1, wherein said plurality of vanes total a number equal to a prime number.
11. The diffuser according to claim 1, further comprising:
- at least one brush cap connected to said motor side of said baffle plate.
12. A motor-fan assembly comprising:
- a field winding;
- an armature having a shaft, said armature rotatably mounted within said field winding;
- a fan attached to said shaft; and
- a diffuser interposed between said fan and said field winding, said diffuser comprising:
- a baffle plate having a motor side and a fan side;
- said baffle plate having an opening therethrough;
- a plurality of vanes extending from said motor side;
- each said vane having an external portion which radially extends from said baffle plate wherein adjacent vanes have a port therebetween; and
- said plurality of vanes directing airflow generated by the fan from said fan side through said ports to said motor side.
13. The motor assembly according to claim 12, wherein each said vane has an internal portion contiguous with said external portion, said internal portion extending toward said opening.
14. The motor assembly according to claim 13, wherein said vanes are curvilinear and spaced apart from each other.
15. The motor assembly according to claim 13, wherein said internal portions terminate prior to reaching said opening so as to collectively form a collection chamber for the airflow.
16. The motor assembly according to claim 12, wherein each said vane has a plate edge at said motor side and ring edge opposite said plate edge.
17. The motor assembly according to claim 16, further comprising:
- a vane support ring connected to at least some of said vanes.
18. The motor assembly according to claim 17, wherein said vane support ring is connected to at least some of said ring edges, said vane support ring having an inner edge with a diameter at least equal to or larger than said baffle plate's diameter.
19. The motor assembly according to claim 12, wherein each said vane comprises a radial turning vane.
20. The motor assembly according to claim 19, wherein said plurality of radial turning vanes total a number equal to a prime number.
21. The motor assembly according to claim 12, wherein said baffle plate is annular.
22. The motor assembly according to claim 12, wherein said plurality of vanes total a number equal to a prime number.
Type: Application
Filed: Jul 29, 2005
Publication Date: Feb 1, 2007
Inventors: James Shawcross (Hudson, OH), David Finkenbinder (Ravenna, OH)
Application Number: 11/193,908
International Classification: F04D 29/44 (20060101);