Cutting blade assembly

Embodiments of the invention provide a cutting blade assembly operably coupleable to a fluid pump. The cutting blade assembly comprises a cutting plate and a cutting hub. The cutting plate may have a front axial surface, an opening, and a plurality of cutting features. Each of the plurality of cutting features may define a pair of cutting edges. The cutting hub may be disposed at least partially within the opening of the cutting plate and may have a cutting arm and fin adjacent to the front axial surface. The cutting arm may define an arcuate front surface having a leading edge. When the cutting plate and the cutting hub are rotated relative to each other, the leading edge of the cutting arm may pass adjacent to the plurality of cutting features so that the relative rotation of the cutting plate and the cutting hub defines a cutting action between the cutting arm and each cutting feature.

REFERENCE TO RELATED APPLICATION

Not Applicable.

BACKGROUND OF THE INVENTION

Cutting blade assemblies are used in a wide variety of applications to generally reduce the particle size of the medium being processed. Grinder pumps include a motor that rotates an impeller and an associated cutting blade assembly. Fluid and debris suspended within the fluid are drawn into the grinder pump where the cutting blade assembly attempts to reduce the particle size of the suspended debris before the impeller pumps the resulting slurry to a downstream location.

One issue common to most cutting blade assemblies, and especially those incorporated in a grinder pump or other fluid pumping applications, is the efficient processing and jam-free operation of the cutting blade assembly given the wide variety of debris encountered. For instance, with grinder pumps, debris including rags, mop heads, beverage containers, diapers, coins, and other objects can clog and jam the cutting blade assembly or place an increased load on the motor driving the cutting blade assembly. The various types of debris present many challenges because stringy debris (e.g., a mop head) can tend to wrap around the cutting blade assembly, resilient debris (e.g., plastic and rubber objects) can tend to wedge between moving parts of the cutting blade assembly, and hard debris (e.g., metallic objects) can wear or damage the cutting features of the cutting blade assembly. One particularly pervasive global problem faced in cutting systems involves the processing of wastewater containing wipes, which can include fibrous materials such as plastic fibers. Fibers can accumulate in gaps and at various interfaces causing a reduction in effectiveness of the cutting system and blockages of the pump.

To address these various problems associated with processing a variety of suspended debris, the drive motor torque can be increased, the cutting blade assembly strengthened, and the allowable particle size increased. However, none of these approaches presents an efficient, cohesive technique to address the persistent issues faced by cutting blade assemblies, and especially those cutting blade assemblies used in grinder pump applications.

SUMMARY OF THE INVENTION

In light of at least the above, a need exists for a cutting blade assembly capable of efficiently and effectively processing various types of debris encountered by the cutting blade assembly.

Some embodiments of the invention provide a cutting blade assembly that may be operably coupleable to a fluid pump. The cutting blade assembly comprises a cutting plate and a cutting hub. The cutting plate may have a front axial surface, an opening, and a plurality of cutting features. Each of the plurality of cutting features may define a pair of cutting edges. The cutting hub may be disposed at least partially within the opening of the cutting plate and may have a cutting arm adjacent to the front axial surface. The cutting arm may define an arcuate front surface having a leading edge. When the cutting plate and the cutting hub are rotated relative to each other, the leading edge of the cutting arm may pass adjacent to the plurality of cutting features so that the relative rotation of the cutting plate and the cutting hub defines a cutting action between the leading edge of the cutting arm and the pair of cutting edges of each cutting feature.

The pair of cutting edges may be radially separated from each other, thereby allowing for multiple cuttings actions to be defined each time the leading edge of the cutting arm passes over an individual cutting feature of the plurality of cutting features. The pair of cutting edges may include a radially inner cutting edge and/or a radially outer cutting edge, and the multiple cutting actions may include: a scissor-type cutting action as the leading edge of the cutting arm passes the radially inner cutting edge; and/or a chipping-type cutting action as the leading edge of the cutting arm passes the radially outer cutting edge.

Each cutting feature of the plurality of cutting features may comprise a C-shaped through hole extending through the cutting plate from the front axial surface to a rear axial surface of the cutting plate.

Each cutting feature of the plurality of cutting features may be approximately equidistant from the opening and a radial edge of the cutting plate.

The cutting plate may include a plurality of deflection features configured to deflect debris radially outward away from the opening when the cutting hub is rotated relative to the cutting plate. Each of the deflection features may be gradually recessed into the front axial surface from an arcuate leading edge that is flush with the front axial surface to an arcuate trailing edge that is recessed into the front axial surface, thereby forming an angled lower surface. Each of the deflection features may include an inner end proximate the opening and an outer end at a radial edge of the cutting plate, and each of the deflection features may gradually widen from the inner end to the outer end. The arcuate leading edge may define a leading radius of curvature and the arcuate trailing edge may define a trailing radius of curvature that is different from the leading radius of curvature.

The cutting hub may further include a plurality of deflection fins configured to urge debris away from the opening of the cutting plate when the cutting hub rotates with respect to the cutting plate.

Other embodiments of the invention provide a cutting blade assembly that may be operably coupleable to a fluid pump. The cutting blade assembly comprises a cutting plate and a cutting hub. The cutting plate may have a front axial surface, an opening, and a plurality of cutting holes. Each of the plurality of cutting holes may define at least one cutting edge. The cutting hub may be disposed at least partially within the opening of the cutting plate and has a cutting arm and a fin. The cutting arm may be adjacent to the front axial surface and may define an arcuate front surface having a leading edge. The fin may be adjacent to the front axial surface and proximate to the cutting arm. When the cutting plate and the cutting hub are rotated relative to each other, the leading edge of the cutting arm may pass adjacent to the plurality of cutting holes so that the relative rotation of the cutting plate and the cutting hub defines a cutting action between the leading edge and the at least one cutting edge and the fins may be configured to urge debris away from the opening of the cutting plate.

The at least one cutting edge may be a pair of cutting edges. The pair of cutting edges may be radially separated from each other, thereby allowing for multiple cuttings actions to be defined each time the leading edge of the cutting arm passes over an individual cutting feature of the plurality of cutting features. Each cutting feature of the plurality of cutting features may comprise a C-shaped through hole extending through the cutting plate from the front axial surface to a rear axial surface of the cutting plate. Each cutting feature of the plurality of cutting features may be approximately equidistant from the opening and a radial edge of the cutting plate. Each one of the pair of cutting edges may be disposed on opposite ends of the corresponding cutting feature.

The cutting plate may further include a plurality of deflection features configured to deflect debris radially outward away from the opening when the cutting hub is rotated relative to the cutting plate. Each of the deflection features may be gradually recessed into the front axial surface from an arcuate leading edge that is flush with the front axial surface to an arcuate trailing edge that is recessed into the front axial surface, thereby forming an angled lower surface. Each of the deflection features may include an inner end proximate the opening and an outer end at a radial edge of the cutting plate, and each of the deflection features may gradually widen from the inner end to the outer end. The arcuate leading edge may define a leading radius of curvature and the arcuate trailing edge defines a trailing radius of curvature that is different from the leading radius of curvature.

In other embodiments, a cutting plate may comprise a front axial surface, a rear axial surface spaced apart from the front axial surface, and a plurality of cutting features formed through the front axial surface and the rear axial surface, wherein each of the plurality of cutting features may define a pair of cutting edges.

In still further embodiments, a cutting hub may comprises a hub portion, at least one cutting arm extending radially outward from the hub portion, and at least one fin extending radially outward from the hub portion and circumferentially spaced from the at least one cutting arm.

DETAILED DESCRIPTION

One embodiment of a cutting blade assembly10is described in the context of a grinder pump. However, the embodiments described herein can be incorporated into other suitable types of cutting devices, such as blenders, mixers, and food processors.

FIGS. 1-4illustrate a cutting blade assembly10configured for use with a grinder pump (not shown). The grinder pump may include the cutting blade assembly10and a fluid pump. The grinder pump may generally draw fluid and debris into and through an inlet in a pump housing of the grinder pump. The fluid and debris may be processed by the cutting blade assembly10and the resulting slurry may be directed through the grinder pump, through an internal manifold, toward an outlet of the pump housing. Specifically, the fluid pump may include an electric motor configured to rotate a central drive shaft about a drive axis12(shown inFIG. 1). The drive shaft may be rotatably fixed to an impeller, which may be seated within the pump housing proximate the inlet. As the impeller rotates, fluid and debris may be drawn toward the inlet and engaged by the cutting blade assembly10.

The cutting blade assembly10of one embodiment of the invention may include a disk-shaped cutting plate14and a cutting hub16. In some instances, the cutting plate14may be seated into a mating cylindrical recess formed into an external surface of the pump housing and surrounding the inlet. The cutting plate14may be rotatably fixed to the mating cylindrical recess by a series of mating features that engage a corresponding plurality of rotational locking notches18of the cutting plate14. Each locking notch18may be recessed into a front axial surface20of the cutting plate14at a radial edge22of the cutting plate14. In some instances, the plurality of locking notches18may be disposed evenly-spaced around the circumference of the cutting plate14.

The cutting hub16is partially received within a central opening24(shown inFIGS. 4, 6, and 7) of the cutting plate14and may be rotatably coupled to the drive shaft of the motor, so that the cutting hub16rotates in unison with the impeller of the fluid pump. Specifically, the cutting hub16includes a central opening26having a keyway28that may be configured to receive the drive shaft of the motor, and to engage the drive shaft of the motor in a keyway-type rotationally-engaged connection.

It will be appreciated that the cutting hub16may alternatively or additionally be configured to rotatably engage the drive shaft of the motor in various other manners without departing from the scope of the invention. For example, in some instances, the central opening26of the cutting hub16may alternatively include a threaded radially-inward facing surface configured to engage a corresponding threaded portion of the drive shaft.

FIGS. 1-12illustrate the structure of and interaction between the cutting plate14and the cutting hub16of the cutting blade assembly10. The cutting plate14and the cutting hub16are configured to establish an axial cutting action (i.e., generally parallel to the drive axis12). This axial cutting action is achieved via relative rotation between the cutting plate14and the cutting hub16.

As shown inFIGS. 6 and 7, the cutting plate14includes the locking notches18, the central opening24, a plurality of deflection features30, and a plurality of cutting features32. The central opening24extends through the cutting plate14from the front axial surface20to a rear axial surface34(shown inFIG. 7) and defines an inwardly-facing radial wall35.

In the illustrated non-limiting example, there may be four deflection features30that are evenly spaced around the circumference of the cutting plate14. In other embodiments, the shape, number, and relative orientation of the deflection features30may be altered to accommodate application-specific requirements.

Each of the deflection features30may be gradually recessed into the front axial surface20from an arcuate leading edge36that is flush with the front axial surface20to an arcuate trailing edge38that is recessed into the front axial surface20, thereby forming an angled lower surface40. Each of the deflection features30may further include an inner end42proximate the central opening24and an outer end44at the radial edge22of the cutting plate14.

Both the arcuate leading edge36and the arcuate trailing edge38may extend generally radially outward from the inner end42toward the outer end44and may curve from the inner end42to the outer end44in a direction of rotation46of the cutting hub16(i.e., the direction that the cutting hub16rotates relative to the cutting plate14during use). The arcuate trailing edge38may also have a smaller radius of curvature than that of the arcuate leading edge36, such that the deflection features30gradually widen from the inner end42to the outer end44. The increasing depth and flow area of the deflection features30may help to gradually deflect debris radially outward away from the central opening24, when the cutting hub16is rotated relative to the cutting plate14.

In the illustrated non-limiting example, there may be twelve cutting features32that may be grouped into four groups of three, each group may be evenly spaced around the circumference of the cutting plate14and may be separated by one of the four deflection features30. In other embodiments, the shape, number, grouping, and relative orientation of the cutting features32may be altered to accommodate application-specific requirements.

Each of the cutting features32may form a generally arcuate or C-shaped through hole extending through the cutting plate14from the front axial surface20to the rear axial surface34and may be approximately equidistant from the central opening24and the radial edge22of the cutting plate14. Each cutting feature32may include an inner end48, an outer end50, a leading sidewall52, and a trailing sidewall54. The inner end48may be disposed proximate the central opening24. The outer end50may be disposed proximate the radial edge22of the cutting plate14. Both the inner end48and the outer end50may be angled or skewed in the direction of rotation46of the cutting hub16. As such, each of the leading sidewall52and the trailing sidewall54, and therefore the cutting feature32as a whole, may form a generally C-shaped element with the concave side of the “C” shape pointing in the direction of rotation46of the cutting hub16.

The leading sidewall52may be disposed on the convex side of the cutting feature32. As best illustrated inFIG. 9, the leading sidewall52may extend between and generally perpendicularly to the front and rear axial surfaces20,34. The trailing sidewall54may be disposed on the concave side of the cutting feature32. As best illustrated inFIGS. 8-10, the trailing sidewall54may extend between the front and rear axial surfaces20,34, at an angle relative to each of the front and rear axial surfaces20,34. Specifically, the trailing sidewall54may extend from the front axial surface20toward the rear axial surface34at an angle with respect to the drive axis12such that the trailing sidewall54is angled in the direction of rotation46of the cutting hub16from the front axial surface20to the rear axial surface34. As such, the cutting feature32may gradually widen from the front axial surface20to the rear axial surface34, and a pair of cutting edges56is formed between the trailing sidewall54and the front axial surface20. Specifically, the trailing sidewall54may define a pair of negative semi-frustoconical shaped surfaces57(i.e., each of the surfaces57form the outside of a semi-frustoconical shaped cavity) connected by a central semi-frustoconical shaped surface59that is oppositely-oriented (i.e., upside-down with respect to the semi-frustoconical shape of the surfaces57). The pair of cutting edges56may be disposed at the narrow ends of the negative semi-frustoconical shaped surfaces57, thereby providing two distinct cutting edges56, separated by the central surface59, for each cutting feature32.

Referring now toFIG. 6, one of the pair of cutting edges56may be disposed proximate the inner end48of the cutting feature32and the other cutting edge56may be disposed proximate the outer end50of the cutting feature32. Thus, the pair of cutting edges56may be radially separated from each other. Therefore, the pair of cutting edges56allows for debris to be cut multiple times each time a single cutting arm58of the cutting hub16passes over a single cutting feature32. As shown inFIG. 2, the leading-most edge of the radially inner cutting edge56may be tangential to ray R1and the leading-most edge of the radially outer cutting edge56may be tangential to ray R2. In one example, the ray R1may be rotationally spaced about the drive axis12from the ray R2by an angle α such that the cutting engagement between the cutting features32and the cutting hub16may be adapted to accommodate application-specific requirements by, for instance, altering the angle α (and/or the contour of the cutting arm58) to adjust the cyclical timing of the cutting engagement.

As shown inFIGS. 2, 15A, 15B, and 15Cthe axial cutting action between the cutting plate14and the cutting hub16can be generally accomplished as axial cutting arms58of the cutting hub16rotate adjacent to the pair of cutting edges56in two separate cutting actions (e.g., a scissor-type, shearing action and a chipping-type action). For example, as the cutting hub16is rotated and one of the axial cutting arms58passes over one of the cutting features32, the leading edge62of the cutting arm58first passes over the radially inner cutting edge56(see, e.g.,FIG. 15A). As the leading edge62passes over the radially inner cutting edge56, a scissor-type, shearing action occurs between the leading edge62and the radially inner cutting edge56due to the arrangement of the cutting feature32with respect to the cutting arm58(see, e.g.,FIG. 15B). Specifically, the cutting feature32is arranged such that, as the cutting hub16rotates, the convex shape of the trailing sidewall54, the convex shape of the leading edge62of the cutting arm58, and the angle α between ray R1and ray R2provides that a majority of the radially inner cutting edge56is arranged close to parallel to the leading edge62of the cutting arm58. With the close to parallel arrangement between the radially inner cutting edge56and the leading edge62, the leading edge62gradually shears over the radially inner cutting edge56.

Conversely, the cutting feature32is arranged such that, as the cutting hub16rotates, a majority of the radially outer cutting edge56may be arranged close to perpendicular, with only a radially outermost portion of the radially outer cutting edge56being disposed at or near parallel to the leading edge62of the cutting arm58. As such, the leading edge62may shear over the portion of the radially outer cutting edge56that is close to perpendicular to the leading edge62, and then abruptly passes over the end portion of the radially outer cutting edge56that is close to parallel with the leading edge62(see, e.g.,FIG. 15C). The abrupt change in relative angles between the radially outer cutting edge56and the leading edge62may result in a chipping-type cutting action. As such, the scissor-type action and the chipping-type action may establish two separate zones of cutting engagement at the pair of cutting edges56as the cutting hub16rotates relative to the cutting plate14.

The cutting hub16may include three circumferentially-spaced axial cutting arms58that may extend radially outward from a central, cylindrical hub portion60. Each of the axial cutting arms58of the cutting hub16may have a leading edge62that is positioned adjacent to the front axial surface20of the cutting plate14. As the cutting hub16rotates, the leading edges62of each axial cutting arm58may shear past the fixed pair of cutting edges56of the cutting features32of the cutting plate14.

In some instances, the arrangement of the cutting features32on the cutting plate14and the spacing between the cutting arms58of the cutting hub16ensure that only one cutting arm58and one cutting feature32are performing a cutting action at any given time. This may allow for a more uniform torque on the pump motor, while also reducing starting torque on the pump motor in the case that debris is disposed between the cutting arm58and the cutting feature32when the pump motor is started.

As shown inFIG. 3, a gap or spacing64between the leading edge62and the front axial surface20can be adjusted based on the particular application requirements, such as desired axial cut size and medium being processed. For example, in some instances, the gap or spacing64may be less than 0.2 mm.

As shown inFIGS. 5 and 10-12, each of the axial cutting arms58may taper from a wider and thicker base portion66adjacent the hub portion60to a narrower and thinner tip portion68at a distal end of the axial cutting arm58. Each axial cutting arm58may have a generally arcuate front surface70and a generally planar rear surface72. The front surface70may be rounded to aid in rejecting suspended debris that has not been sufficiently reduced in size by the axial cutting action. An undercut74may be formed in the rear surface72to create a low pressure zone on the back edge76of the axial cutting arm58to help prevent debris from being trapped or becoming stagnant as the axial cutting arm58rotates. The arcuate front surface70of the cutting arms58may also minimize the magnitude of a torque spike of the motor when debris comes into abrupt contact with the cutting hub16.

The cutting hub16may further include a connection cap recess78, a plate engagement portion80(shown inFIGS. 11 and 12), and a plurality of deflection fins82. The connection cap recess78may be recessed into a front surface84of the hub portion60. The connection cap recess78may be configured to receive and/or engage a corresponding connection cap (not shown) that is configured to engage the drive shaft of the motor to lock the cutting hub16into engagement with the cutting plate14.

The plate engagement portion80may define a generally cylindrical shape that extends away from a rear surface86of the hub portion60. The plate engagement portion80may have a diameter that corresponds to a diameter of the central opening24of the cutting plate14. As such, the plate engagement portion80may be received within the central opening24of the cutting plate14.

The plurality of deflection fins82may extend radially outward from the hub portion60, at a lower end of the hub portion60, between adjacent cutting arms58. In some instances, the rear surface of each of the deflection fins82may be flush with the rear surface86of the hub portion. As best shown inFIG. 2, when the plate engagement portion80of the cutting hub16is received within the central opening24of the cutting plate14, a distal tip88of each fin82extends radially outward, past the inner ends42of the deflection features30, to approximately the inner ends48of the cutting features32. As such, the fins82may be configured to urge debris away from the central opening24of the cutting plate14while the cutting hub16is rotated. Accordingly, with reference toFIG. 5, the fins82may aide in preventing debris from becoming lodged between the inwardly-facing radial wall35of the central opening24and an outwardly-facing radial wall90of the plate engagement portion80, which can inhibit relative rotation between the cutting plate14and the cutting hub16.

In the illustrated non-limiting example, there are three deflection fins82that may be evenly spaced around the circumference of the cutting hub16. In other embodiments, the shape, number, and relative orientation of the deflection fins82may be altered to accommodate application-specific requirements.

With reference toFIGS. 3 and 13, the cutting hub16may further include a node92that is configured to direct debris away from the drive axis12. The node92may extend axially from the front surface84of the hub portion60an axial distance D1. The node92may define a leading portion94and a trailing portion96that may be connected by an intermediate axial portion98. The intermediate axial portion98may be substantially parallel to the front surface84of the hub portion60. The node92may span a circumferential distance D2from a leading lower corner91to a trailing lower corner93. In some instances, the circumferential distance D2may be about three times the axial distance D1, where “about” is within 10%. For example, the axial distance D1may be about 5 mm and the circumferential distance D2may be about 15 mm, where “about” is within 10%.

In some instances, the slope/angle of the leading portion94relative to the front surface84is more gradual than that of the trailing portion96. For example, a leading angle β between the leading portion94and the front surface84of the hub portion60may be any angle between about 110-160 degrees, and preferably about 135 degrees, where “about” is within 10%. As another example, a trailing angle γ between the trailing portion96and the front surface84may be any angle between about 100-140 degrees, and preferably about 120 degrees, where “about” is within 10%. In other exemplary embodiments, the leading angle β may greater than 90 degrees and the trailing angle γ may be greater than 90 degrees.

Further, the node92may include a leading upper corner95and a trailing upper corner97. In some instances, the leading upper corner95and the trailing upper corner97may have radii of curvature that are about three times the radii of curvature of the leading lower corner91and the trailing lower corner93, where “about” is within 10%. For example, the leading upper corner95and the trailing upper corner97may each have a radius of curvature of between about 2-5 mm, and preferably about 3 mm, and the leading lower corner91and the trailing lower corner93may each have a radius of curvature of about 1-3 mm, and preferably about 1 mm, where “about” is within 10%.

Referring now toFIG. 14, the node92may also define an interior surface100and an exterior surface102that may both generally taper toward the intermediate axial portion98, with the exterior surface102skewed at a greater angle than the interior surface100, relative to an axial direction104of the drive axis12. For example, the exterior surface102may be arranged at an angle δ from the axial direction104and the interior surface100may be arranged at an angle ε from the axial direction104. In some instances, the angle δ may be any angle between about 10-25 degrees and the angle ε may be any angle between about 0-2 degrees, where “about” is within 10%. As the cutting hub16rotates, the node92may be configured to deflect and reject debris away from the drive axis12and toward the various cutting features32. With this node92form factor (e.g., elevation/cam profile), debris (e.g., cloths, wipes, etc.) that will otherwise surround the cutting rotor during suction, are preferably diverted and fed, for instance, step-by-step to the cutting features. This helps enable a more continuous cutting process without longer undercuts and reduced potential for excessive loading. In addition, the flow-optimized geometry of these node92features reduces and limits power loss during operation.

In the illustrated non-limiting example, there may be a single node92extending from the hub portion60. In other embodiments, the placement, shape, number, and relative orientation of the node92may be altered to accommodate application-specific requirements.

Once the axial cutting action is complete, the resulting slurry may be urged by the rotating impeller of the fluid pump, through the internal manifold, toward the outlet of the pump housing. The illustrated construction of the cutting plate14and the cutting hub16(as shown inFIG. 2) provides a generally constant inlet area that improves the efficiency of the overall cutting blade application. For instance, the cross sectional area of the central opening24in the cutting plate14may be generally constant over the axial length of the central opening24. The relatively constant inlet area minimizes the velocity changes of the fluid/slurry as it travels through the cutting blade assembly10and associated pump components. In the cutting blade assembly10, the fluid speed may be increased as it passes into and through the cutting features32, reduces slightly downstream of the cutting features32, and maintains approximately the same velocity before reaching the impeller. The torque required to operate the cutting blade assembly10may be further minimized by the swept back configuration of the axial cutting arms58. Furthermore, the cutting configuration employed in the axial cutting action may reduce the torque requirements as compared to a conventional cutting action. The reduction in typical cut size achieved by having two separate cutting edges56for each cutting feature32may also reduce the torque required.

It will be understood that a variety of materials, including metals, plastics, and composites may be used to construct the cutting blade assembly given the specific application requirements.