(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2014/0196570 A1
`Small et al.
`(43) Pub. Date:
`Jul. 17, 2014
`
`US 2014O196570A1
`
`(54) LIGHTENED ROTATING MEMBER AND
`METHOD OF PRODUCING SAME
`(71) Applicant: FTS INTERNATIONAL, Fort Worth,
`TX (US)
`(72) Inventors: Tony M. Small, Fort Worth, TX (US);
`Pankaj Patel, Fort Worth, TX (US)
`
`(73) Assignee: FTS INTERNATIONAL, Fort Worth,
`TX (US)
`(21) Appl. No.: 13/740,989
`(22) Filed:
`Jan. 14, 2013
`Publication Classification
`
`(51) Int. Cl.
`FI6C3/06
`B23P I 7/00
`
`(2006.01)
`(2006.01)
`
`(52) U.S. Cl.
`CPC. F16C3/06 (2013.01); B23P 1700 (2013.01)
`USPC .................................. 74/603; 29/592: 29/428
`
`(57)
`
`ABSTRACT
`
`A lightened rotating member for a machine. The lightened
`member includes a plurality of radially machined penetra
`tions within at least one main bearing Support journal of the
`rotating member. The plurality of penetrations is formed
`around the circumference of the main bearing journal face,
`with the penetration centerline directed radially toward the
`rotating member's axial centerline. An even number of pen
`etrations may be utilized with minimal adverse effect on the
`balance of the rotating member. Odd numbers of penetrations
`may require Subsequent rebalancing. The rotating member
`may be any rotating member that utilizes one or more main
`bearing Support journals.
`
`
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`US 2014/O 196570 A1
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`Jul. 17, 2014
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`LIGHTENED ROTATING MEMBER AND
`METHOD OF PRODUCING SAME
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`0001. Not Applicable
`
`STATEMENT REGARDING FEDERALLY
`SPONSORED RESEARCH ORDEVELOPMENT
`0002. Not Applicable
`
`THE NAMES OF THE PARTIES TO AJOINT
`RESEARCH AGREEMENT
`0003) Not Applicable
`
`INCORPORATION-BY-REFERENCE OF
`MATERIAL SUBMITTED ON A COMPACT DISC
`0004) Not Applicable
`
`BACKGROUND OF THE INVENTION
`0005 1. Field of the Invention
`0006. The present invention relates to reciprocating posi
`tive-displacement pumps and engines and, more specifically,
`to lightened rotating members within positive displacement
`pumps and engines and methods of producing same.
`0007 2. Description of Related Art including information
`disclosed under 37 CFR 1.97 and 1.98
`0008 Horizontal drilling and well stimulation processes
`have revolutionized the oil and gas industry with regard to the
`optimization of hydrocarbon extraction. Shale areas once
`thought unreachable are now within range of the horizontal
`drilling technology, with most shale gas wells having an
`average depth from the surface of between 7,500 and 13,000
`feet with a horizontal run in the pay Zone of 2,000 to 3,000 feet
`on average, if not better. Further, wells in shale areas that were
`once thought to be dry or of limited productivity are now
`capable of efficient (and profitable) production due to the use
`of advanced stimulation processes, specifically hydraulic
`fracturing of the well bore in the specific hydrocarbon Zones.
`0009 Every shale Zone is composed differently, requiring
`somewhat different drilling and well stimulation techniques
`to make the well economically viable. Because of the atten
`dant high costs of horizontal drilling, it is necessary that Such
`a well produce as much hydrocarbon as possible in as short of
`a time as possible to allow the well operator to recover these
`enormous upfront costs. As such, hydraulic fracturing is used
`quite extensively to open up the pores in the Surrounding shale
`to allow trapped hydrocarbons to flow freely.
`0010 Rock pressures beneath the earth's surface are quite
`extreme, especially given the depths to which the well holes
`must be drilled to reach the pay Zones. As a rule of thumb, the
`pressures exerted by the surrounding rockata depth of 10,000
`feet measures approximately 10,000 PSI, but can be as high as
`15,000 PSI or greater depending on the shale characteristics.
`When a well hole is drilled to this depth, this enormous
`pressure is felt on the walls of the lateral run. Consequently, to
`fracture the Surrounding shale formation requires the ability
`to exceed this Surrounding pressure.
`0011
`Hydraulic fracturing pumps, or “frac pumps' as
`they are known in the industry, are relatively massive positive
`displacement pumps capable of countering this enormous
`pressure at these extreme depths. Fracturing fluid (“frac
`
`fluid'), often containing proppants and/or slickwater, are
`pumped downhole by the frac pump, relying on the relative
`incompressibility of the frac fluid to transmit the frac pump
`pressure at the Surface to an adequate pressure in the pay Zone
`to cause the fractures to form. However, pressure is not the
`only requirement. Because of the extreme distance that the
`frac fluid must travel, in addition to the large number of
`perforations in the lateral run through which the frac fluid
`must flow, a very high volumetric flow rate must beachieved.
`Thus, a frac pump is typically called upon to continuously
`pump frac fluid at a maximum pressure of around 15,000 PSI
`with a maximum flow rate of over 1132 GPM downhole,
`depending on the rpm and plunger size, which requires an
`input power of upwards of 2,500 BHP to achieve this kind of
`performance from the pump.
`0012 Positive displacement frac pumps typically come in
`a triplex (three cylinder) or quintuplex (five cylinder) con
`figuration. FIG. 1 depicts a typical quintuplex configuration,
`but is equally as representative of a triplex configuration as
`the only functional difference is an additional two cylinders.
`As depicted, the pump consists of a power end (102) and a
`fluid end (104). The power end includes a heavy steel block
`casing that houses the power components including: the input
`shaft that drives the bull gear, which is attached to the crank
`shaft, which is in turn attached to the plungers by crosshead/
`connecting rods. The fluid end (104) also includes a heavy
`steel block casing that houses the positive displacement
`plungers that work the frac fluid, drawing the fluid in through
`an intake manifold (106) and out under extreme pressure and
`flow rate through an output manifold (108). One-way valves
`within the fluid end (104) manage the flow. To handle such
`extreme operating conditions, each of these components must
`typically be forged from high strength alloy steel and, conse
`quently, is exceedingly heavy.
`0013 Oil and gas wells are usually located in very remote
`locations, requiring preparation of well sites with private
`roads for access from state highways. Thus, to move frac
`pumps and Supporting equipment to such locations it is nec
`essary to prepare specialized trailers. FIG. 2 depicts a typical
`frac pump semi-trailer with the systems required for opera
`tion of the frac pump at a remote well site. The frac pump
`(202), although one of many components necessary for the
`fracturing process to take place, tends to be one of the heaviest
`component on the trailer and is positioned directly over the
`trailer axles. The frac pump (202) fluid end is connected to a
`frac fluid blender (204) through a series of piping and valves
`(206). A high-horsepower diesel engine (208) connects to the
`frac pump (202) power end input shaft through a transmission
`(210) and drive shaft. For continuous operation the diesel
`engine (208) is also provided with a cooling system (212) and
`a reserve of fuel (214). In all, the tractor, trailer, and compo
`nents can very easily exceed the standard 80,000 LBS maxi
`mum road weight limit established by the U.S. and various
`state Department of Transportation offices for operation on
`public roadways. In fact, it is not uncommon for Such a
`tractor/trailer combination to weigh as much as 100,000 LBS
`or greater, requiring costly special permits to transport over
`the roadways and reinforced semi-trailers having extra axles
`and wheels. The result is higher costs for the operator due to
`the permitting process, equipment purchase, and mainte
`nance, as well as limited transportability due to the require
`ments for a sufficiently strong and durable roadway to deliver
`the rig to a well site.
`
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`US 2014/O 196570 A1
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`Jul. 17, 2014
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`0014 What is needed is a way to reduce this overall weight
`without sacrificing the strength and integrity of the frac pump
`and Support equipment. The present invention Substantially
`reduces the overall weight of the frac pump assembly without
`compromising the torsional strength or balance of the rotating
`internal components. Further, the present invention also
`reduces the moment of inertia of the rotating internal compo
`nents, thereby increasing overall efficiency and lowering the
`power consumption. Further still, the present invention
`achieves this in an unobtrusive fashion, such that it is not
`readily visible to the casual maintenance repairperson. Other
`benefits are taught herein, as will be readily appreciated fol
`lowing a reading and understanding of the following detailed
`description.
`
`BRIEF SUMMARY OF THE INVENTION
`
`Disclosed herein is a lightened rotating member for
`00.15
`a machine, the rotating member comprising: a plurality of
`radial penetrations, the radial penetrations formed around the
`circumference of at least one main bearing Support journal.
`Another embodiment includes a plurality of radial penetra
`tions, the radial penetrations formed around the circumfer
`ence of each of a plurality of main bearing Supportjournals. In
`another embodiment the radial penetrations are blind holes.
`In another embodiment the radial penetration centerlines are
`evenly spaced around the circumference. In another embodi
`ment that includes an even number of evenly-spaced radial
`penetrations, there is at least one radial penetration dimension
`that differs in response to dynamic balancing of the rotating
`member. In another embodiment one or more grooves are
`formed around the circumference of the at least one main
`bearing Support journal. Another embodiment includes a
`bearing race that is independently positional about the pen
`etrated bearing Support journal. Another embodiment
`includes a bearing race that is independently positional about
`the penetrated bearing Support journal, wherein positioning
`of the bearing race Substantially conceals the radial penetra
`tions. In another embodiment the radial penetrations are con
`figured to reduce the inertia of the rotating member without
`Substantially reducing the torsional stability and balance of
`the rotating member.
`0016. Also disclosed is a method for lightening the weight
`of a rotating member of a positive displacement device, the
`method steps comprising: forming a plurality of radial pen
`etrations around the circumference of at least one main bear
`ing Support journal. Steps in another embodiment include
`forming a plurality of radial penetrations around the circum
`ference of each of a plurality of main bearing Support jour
`nals. Steps in another embodiment include dynamically bal
`ancing the rotating member by varying the dimension of one
`or more of the radial penetrations. Steps in another embodi
`ment include forming one or more grooves around the cir
`cumference of the at least one main bearing Support journal.
`In another embodiment the radial penetrations are blind
`holes. In another embodiment the radial penetration center
`lines are evenly spaced around the circumference. Steps in
`another embodiment include installing a bearing race that is
`independently positional about the penetrated bearing Sup
`port journal. Steps in another embodiment include installing
`a bearing race that is independently positional about the pen
`etrated bearing Support journal, wherein positioning of the
`bearing race Substantially conceals the radial penetrations. In
`another embodiment the radial penetrations are configured to
`
`reduce the inertia of the rotating member without substan
`tially reducing the torsional stability and balance of the rotat
`ing member.
`
`BRIEF DESCRIPTION OF THE SEVERAL
`VIEWS OF THE DRAWING(S)
`0017. The present invention will be more fully understood
`by reference to the following detailed description of the pre
`ferred embodiments of the present invention when read in
`conjunction with the accompanying drawings, wherein:
`0018 FIG. 1 is a perspective view of a typical quintuplex
`fracturing pump assembly:
`0019 FIG. 2 depicts a typical frac pump semi-trailer with
`the systems required for operation of the frac pump at a
`remote well site;
`0020 FIG.3 depicts a perspective view of an embodiment
`of the present invention in the form of a crankshaft rotating
`member separated from the power end housing of a frac pump
`for clarity;
`0021
`FIG. 4 is an end axial view of the embodiment,
`highlighting the placement and spacing of the lightening pen
`etrations;
`0022 FIG. 5 is an end axial view of another embodiment,
`highlighting the placement and spacing of a different number
`of lightening penetrations;
`0023 FIG. 6 depicts the embodiment with roller bearings
`installed on the main bearing journals; and
`0024 FIG. 7 depicts the interior of a frac pump, highlight
`ing the construction and location of the crankshaft within the
`main bearing bores and webbing with the rotating member
`embodiment installed.
`0025. The above figures are provided for the purpose of
`illustration and description only, and are not intended to
`define the limits of the disclosed invention. Use of the same
`reference number in multiple figures is intended to designate
`the same or similar parts. Furthermore, if the terms “top.”
`“bottom.” “first,” “second,” “upper,” “lower,” “height.”
`“width.” “length.” “end,” “side,” “horizontal,” “vertical,” and
`similar terms are used herein, it should be understood that
`these terms have reference only to the structure shown in the
`drawing and are utilized only to facilitate describing the par
`ticular embodiment. The extension of the figures with respect
`to number, position, relationship, and dimensions of the parts
`to form the preferred embodiment will be explained or will be
`within the skill of the art after the following teachings of the
`present invention have been read and understood.
`
`DETAILED DESCRIPTION OF THE INVENTION
`0026 FIG.3 depicts a perspective view of a first embodi
`ment of a rotating member utilizing the present invention in
`the form of a crankshaft rotating-member separated from the
`power end housing of a frac pump. As shown, the crankshaft
`(300), in triplex configuration, features three rod bearing
`journals (308) supported by four main bearing journals (302).
`The main bearing journals have a bearing face (304) upon
`which an inner bearing race is mounted for a roller main
`bearing assembly (see FIG. 6). A plurality of blind hole pen
`etrations (306) is formed in each bearing face (304) along the
`circumferential centerline. Although a triplex configuration is
`described for the present embodiment, other embodiments
`are possible and the same principles apply. For example, in a
`quintuplex configuration the crankshaft would have five rod
`bearing journals supported by at least six main bearing jour
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`Jul. 17, 2014
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`nals. One of ordinary skill in the art to which the invention
`pertains will appreciate that a rotating assembly having any
`number of main bearing Support journals is within the scope
`of the claims herein.
`0027. The crankshaft (300) may be manufactured from
`alloy steel, cast materials, or forged materials, so long as
`Sufficient material exists in the main bearing journal to allow
`for the removal of a portion of the material in the novel
`manner as disclosed herein. Accordingly, one of ordinary
`skill in the art to which the invention pertains will understand
`that the invention applies equally to rotating members manu
`factured from any material appropriate for the application.
`Moreover, one of ordinary skill will understand that the
`machining technique for forming the penetrations depends
`upon the material used, as well as the desired accuracy of the
`resulting penetrations. While certain materials may be
`machined, others may require formation of the penetrations
`during the casting or forging process.
`0028 FIG. 4 provides an end-on axial view of the embodi
`ment, highlighting the placement and spacing of the lighten
`ing holes (306). As shown, the present embodiment utilizes
`ten penetrations in each main bearing journal bearing face
`(304), with each penetration equally spaced around the jour
`nal circumference on an angle (402) of 36 degrees in this
`embodiment. Each penetration is formed by machining the
`material to a fixed depth along the radius of the journal toward
`the axial centerline of the crankshaft to a depth that does not
`interfere with internal oiling passages that Supply pressurized
`oil to the rod and/or main bearings during operation. This
`creates a blind hole for the penetration, which is subsequently
`left void of materialso as to remove mass from the journal.
`0029. For the sake of balance it is important that the
`dimensions of each penetration be equal. Thus, the depth of
`each penetration should be no greater than the shallowest
`penetration with regard to potential interference with an oil
`ing passage. However, in another embodiment one or more of
`the holes may differ in dimension, which may be tolerated by
`statically and/or dynamically balancing the rotating assembly
`once the formation of the penetrations is complete. Because
`the mass is reduced at the outer diameter of the journal, not
`only is the weight of the crankshaft reduced, but the overall
`inertia for the journal (and consequently, the crankshaft) is
`reduced as well. In the present embodiment the addition often
`penetrations in each main bearing journal reduces the overall
`weight of the rotating assembly (300) by approximately 200
`to 300 LBS, resulting in a substantial weight reduction.
`0030. In yet another embodiment having no interfering
`main bearing journal oiling passages, it is possible to machine
`the radial penetrations completely through the axial center
`line. However, Such a configuration might impact the tor
`sional stability of the rotating member, which might limit the
`amount of horsepower input that the member could handle.
`Another embodiment may utilize a combination of through
`holes and blind holes within one or more journals so long as
`a proper static and dynamic balancing of the rotating member
`is performed. In yet another embodiment the journal bearing
`face (304) features one or more grooves machined around the
`diameter of the bearing face (304) to supplement the removal
`of material for the purposes described herein.
`0031. As previously stated, the plurality of penetrations
`(306) is equally spaced around the journal (304) circumfer
`ence, along the journal bearing face (304) circumferential
`centerline. Other embodiments can have a greater or lesser
`number of penetrations and may even have certain journals
`
`without penetrations. For example, FIG. 5 depicts an end-on
`axial view of another embodiment, highlighting the place
`ment and spacing of eight lightening penetrations, with the
`angle (502) between the centerline of each measuring
`approximately 45 degrees. In another embodiment twelve
`penetrations are utilized, with the angle between the center
`line of each measuring 30 degrees. An even number of pen
`etrations is utilized to ensure minimal effect on overall bal
`ance of the rotating assembly. However, other embodiments
`may utilize an odd number of radial penetrations if attention
`is given to the static and/or dynamic balance of the resulting
`rotating assembly.
`0032 FIG. 6 depicts the present embodiment of the rotat
`ing member with roller bearings (602) installed on the main
`bearing journals. When the roller bearings (602) are in place,
`the penetrations are essentially shielded from view. The roller
`bearing (602) features an inner bearing race that contacts the
`main bearing journal face (304), is independently positional
`about the journal face (304) surface, and covers the penetra
`tions thereby keeping matter from accumulating therein. An
`outer bearing race is mounted in the power end housing (see
`FIG. 7). Although the present embodiment utilizes roller
`bearings along the main bearing journals, other configura
`tions are possible and are within the scope of the invention.
`For example, another embodiment utilizes sleeve bearings
`instead of roller bearings. Use of sleeve bearings on internal
`rotating members is popular in the automotive industry. In
`Such a configuration it may be necessary to add a chamfer to
`the penetration (306) outer lip to prevent shearing of the oil
`film from the bearing Surface and Subsequent galling or strip
`ping off of the bearing material.
`0033 FIG. 7 depicts the interior of a frac pump housing
`(702), highlighting the construction and location of the crank
`shaft rotating member (300) embodiment within the main
`bearing bores and webbing (704). As shown, the rotating
`member (300) main bearings (602) roll within outer bearing
`races (706) that are mounted within bores in the main bearing
`webbing (704). These webs (704) provide positional support
`for the rotating member (300) and are dimensioned for
`adequate strength and rigidity to dissipate the tremendous
`forces generated within the frac pump during operation. The
`bearing face (304), during operation, Supports the forces
`exhibited on the crankshaft by the reciprocating connecting
`rod/piston/plunger arrangement by transferring the compres
`sive forces encountered by the plunger/piston/connecting rod
`assembly from the rod bearing journal (308) through the main
`bearing journal bearing face (304), the roller bearings (602),
`the outer bearing races (706), into the support webs (704) and
`ultimately to the power end housing (702) where the forces
`are dissipated.
`0034. Although the embodiment described herein focused
`on the crankshaft of a hydraulic fracturing pump as a rotating
`member that benefits from the methods and treatments taught
`herein, the invention is also applicable to other rotating mem
`bers and other uses. For example, the frac pump pinion shaft
`(702) is supported within the housing by bearing journals as
`well. Machining radial lightening holes as taught herein in
`one or more of the bearing journal Surfaces would, likewise,
`reduce overall pinion shaft weight and inertia without
`adversely affecting the pinion shafts torsional strength.
`Pumps having similar rotating components that might benefit
`from the invention include concrete, water, and other well
`treatment pump devices.
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`0035. Further still, internal combustion engines (gasoline,
`diesel, alternative fuels, or the like) would also benefit from
`the invention taught herein. For example, a typical internal
`combustion engine utilizes a crankshaft or rotor (i.e., rotary
`internal combustion engine) having main bearing journals for
`primary Support. Machining radial lightening holes as taught
`herein in these main bearing journal Surfaces would, likewise,
`lower the overall crankshaft weight and inertia without
`adversely impacting the torsional strength and balance of the
`overall rotating assembly. Other internal rotating members
`that are Supported by main bearing journals (for example, the
`camshaft, counterbalance shaft, transmission input shaft,
`drive axles, etc.) would likewise benefit from this novel treat
`ment.
`0036. The invention may be embodied in other specific
`forms without departing from the spirit or essential charac
`teristics thereof. The present embodiments are therefore to be
`considered in all respects as illustrative and not restrictive.
`Accordingly, the scope of the invention is established by the
`appended claims rather than by the foregoing description. All
`changes which come within the meaning and range of equiva
`lency of the claims are therefore intended to be embraced
`therein. Further, the recitation of method steps does not
`denote a particular sequence for execution of the steps. Such
`method steps may therefore be performed in a sequence other
`than that recited unless the particular claim expressly states
`otherwise.
`1. A lightened rotating member for a machine, the rotating
`member comprising:
`a plurality of radial penetrations, the radial penetrations
`formed around the circumference of at least one main
`bearing Support journal.
`2. The lightened rotating member of claim 1, further com
`prising:
`a plurality of radial penetrations, the radial penetrations
`formed around the circumference of each of a plurality
`of main bearing Support journals.
`3. The lightened rotating member of claim 1, wherein the
`radial penetrations are blind holes.
`4. The lightened rotating member of claim 1, wherein the
`radial penetration centerlines are evenly spaced around the
`circumference.
`5. The lightened rotating member of claim 1, further com
`prising:
`an even number of evenly-spaced radial penetrations,
`wherein at least one radial penetration dimension differs
`in response to dynamic balancing of the rotating mem
`ber.
`6. The lightened rotating member of claim 1, further com
`prising:
`one or more grooves formed around the circumference of
`the at least one main bearing Support journal.
`
`7. The lightened rotating member of claim 1, further com
`prising:
`a bearing race that is independently positional about the
`penetrated bearing Support journal.
`8. The lightened rotating member of claim 1, further com
`prising:
`a bearing race that is independently positional about the
`penetrated bearing Support journal, wherein positioning
`of the bearing race Substantially conceals the radial pen
`etrations.
`9. The lightened rotating member of claim 1, wherein the
`radial penetrations are configured to reduce the inertia of the
`rotating member without Substantially reducing the torsional
`stability and balance of the rotating member.
`10. A method for lightening the weight of a rotating mem
`ber of a positive displacement device, the method steps com
`prising:
`forming a plurality of radial penetrations around the cir
`cumference of at least one main bearing Support journal.
`11. The method of claim 10, the method steps further
`comprising:
`forming a plurality of radial penetrations around the cir
`cumference of each of a plurality of main bearing Sup
`port journals.
`12. The method of claim 10, the method steps further
`comprising:
`dynamically balancing the rotating member by varying the
`dimension of one or more of the radial penetrations.
`13. The method of claim 10, the method steps further
`comprising:
`forming one or more grooves around the circumference of
`the at least one main bearing Support journal.
`14. The method of claim 10, wherein the radial penetra
`tions are blind holes.
`15. The method of claim 10, wherein the radial penetration
`centerlines are evenly spaced around the circumference.
`16. The method of claim 10, the method steps further
`comprising:
`installing a bearing race that is independently positional
`about the penetrated bearing Support journal.
`17. The method of claim 10, the method steps further
`comprising:
`installing a bearing race that is independently positional
`about the penetrated bearing Support journal, wherein
`positioning of the bearing race Substantially conceals the
`radial penetrations.
`18. The method of claim 10, wherein the radial penetra
`tions are configured to reduce the inertia of the rotating mem
`ber without substantially reducing the torsional stability and
`balance of the rotating member.
`
`k
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`k
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`k
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