Piston Pump and Method of Manufacturing the Same

This application is a continuation of and claims priority of U.S. application Ser. No. 18/658,876, filed May 8, 2024, which is hereby incorporated herein by reference in its entirety.

This application relates to the field of piston pumps and methods of manufacturing piston pumps and parts thereof.

Piston pumps are pumps that use reciprocating motion of pistons to move fluid through a system. Piston pumps are classified as positive displacement pumps, which move a volume of fluid for each cycle. In traditional piston pumps, the cycle for each piston includes a suction stroke, in which the piston is moved a distance to draw the volume of fluid into a chamber, and a discharge stroke, in which the piston is returned that distance to displace the volume of fluid from the chamber.

In accordance with one aspect of this disclosure, a piston pump has a pump housing having a crankshaft chamber, a pumping chamber, and a plurality of piston passages, the piston passages extending from the crankshaft chamber to the pumping chamber. The piston pump further has a crankshaft rotatably mounted in the crankshaft chamber, the crankshaft having a longitudinally extending crankshaft rotation axis, and a plurality of cams distributed along the crankshaft axis. Each cam has a plurality of cam noses and a plurality of cam heels, the cam noses circumferentially alternating with the cam heels around the crankshaft axis, the cam noses all having a nose radius, the cam heels all having a heel radius, the nose radius being greater than the heel radius, a cam stroke length that is a difference between the nose radius and the heel radius, and a cam material abrasion resistance. The piston pump further has a plurality of pistons, each piston corresponding to a cam of the plurality of cams, each piston slidably mounted in a corresponding piston passage of the plurality of piston passages between a nose position and a heel position. Each piston has a piston shaft extending within the corresponding piston passage, the piston shaft having a first shaft end positioned in the crankshaft chamber and a second shaft end; and a sacrificial piston crown removably connected to the first shaft end, the piston crown having a cam engagement side in contact with the corresponding cam, the cam engagement side having a piston crown material abrasion resistance that is less than the cam material abrasion resistance. The piston pump further has a plurality of resiliently compressible piston biases, each piston bias biasing a corresponding piston of the plurality of pistons toward the crankshaft and maintaining constant contact between the cam engagement side of the piston crown and the corresponding cam of the piston as the crankshaft rotates, the piston being in the nose position when the cam engagement side is in contact with the nose of the cam, and the piston being in the heel position when the cam engagement side is in contact with the heel of the cam.

In accordance with one aspect of this disclosure, a piston pump has a pump housing having a crankshaft chamber, a pumping chamber, and a plurality of piston passages, the piston passages extending from the crankshaft chamber to the pumping chamber. The piston pump further has a crankshaft rotatably mounted in the crankshaft chamber, the crankshaft having a longitudinally extending crankshaft rotation axis, and a plurality of cams distributed along the crankshaft axis. The piston pump further has a plurality of pistons, each piston corresponding to a cam of the plurality of cams, each piston slidably mounted in a corresponding piston passage of the plurality of piston passages between a nose position and a heel position. Each piston has a piston shaft extending within the corresponding piston passage, the piston shaft having a first shaft end positioned in the crankshaft chamber and a second shaft end. The piston shaft has a unitary construction of solid metal and an exterior surface. At least a portion of the exterior surface has an abrasion-resistance surface treatment. Each piston further has a piston crown connected to the first shaft end, the piston crown having a cam engagement side in contact with the corresponding cam. The piston pump further has a plurality of resiliently compressible piston biases, each piston bias biasing a corresponding piston of the plurality of pistons toward the crankshaft and maintaining constant contact between the cam engagement side of the piston crown and the corresponding cam of the piston as the crankshaft rotates.

In accordance with one aspect of this disclosure, a piston pump has an extrusion-formed pump housing having a crankshaft chamber, a pumping chamber, and a plurality of piston passages, the piston passages extending from the crankshaft chamber to the pumping chamber. The piston pump further has an extrusion-formed crankshaft rotatably mounted in the crankshaft chamber, the crankshaft having a longitudinally extending crankshaft rotation axis, and a plurality of cams distributed along the crankshaft axis. The piston pump further has a plurality of pistons, each piston corresponding to a cam of the plurality of cams, each piston slidably mounted in a corresponding piston passage of the plurality of piston passages between a nose position and a heel position. Each piston has a piston shaft extending within the corresponding piston passage, the piston shaft having a first shaft end positioned in the crankshaft chamber and a second shaft end, and a piston crown connected to the first shaft end, the piston crown having a cam engagement side in contact with the corresponding cam. The piston pump further has a plurality of resiliently compressible piston biases, each piston bias biasing a corresponding piston of the plurality of pistons toward the crankshaft and maintaining constant contact between the cam engagement side of the piston and the corresponding cam of the piston as the crankshaft rotates.

In accordance with one aspect of this disclosure, a method of mass-producing crankshafts for a piston pump includes segmenting a crankshaft axle precursor formed as an elongated circular rod into a first crankshaft axle and a second crankshaft axle, each of the first and second crankshaft axles having an axle length; extruding a cam precursor as an elongated non-circular rod; segmenting the cam precursor into a first plurality of cams and a second plurality of cams, each of the cams in the first and second plurality of cams having a cam width; machining a central axle opening through each cam of the first and second plurality of cams, the central axle opening having an opening diameter sized to receive an outer diameter of the crankshaft axles; mounting the first plurality of cams onto the first crankshaft axle by inserting the first crankshaft axle into the central axle opening of the first plurality of cams, and mounting the second plurality of cams onto the second crankshaft axle by inserting the second crankshaft axle into the central axle opening of the second plurality of cams; and rigidly connecting the first plurality of cams to the first crankshaft axle along the axle length of the first crankshaft axle, and rigidly connecting the second plurality of cams to the second crankshaft axle along the axle length of the second crankshaft axle.

In accordance with one aspect of this disclosure, a method of mass-producing pistons for a piston pump includes segmenting a piston shaft precursor formed as an elongated rod into a first piston shaft and a second piston shaft, each of the first and second piston shafts having a shaft length extending from a first shaft end to a second shaft end; applying an abrasion-resistance treatment to a surface of the first piston shaft for at least a portion of the shaft length of the first piston shaft, and applying an abrasion-resistance treatment to a surface of the second piston shaft for at least a portion of the shaft length of the second piston shaft; extruding a piston crown precursor formed as an elongated profile having a cam engagement side and an opposed shaft engagement side; segmenting the piston crown precursor into a first piston crown and a second piston crown, each of the first and second piston crowns having the cam engagement side, the shaft engagement side, and a crown width; and connecting the shaft engagement side of the first piston crown to the first shaft end of the first piston shaft, and connecting the shaft engagement side of the second piston crown to the first shaft end of the second piston shaft.

In accordance with one aspect of this disclosure, a method of mass producing piston pumps includes the method of mass producing crankshafts in accordance with one aspect of this disclosure; the method of mass producing pistons in accordance with one aspect of this disclosure to produce a first plurality of pistons and a second plurality of pistons; extruding a pump main body precursor formed as an elongated profile having a top wall, a bottom wall, and a rear wall extending between the top and bottom walls; segmenting the pump main body precursor into a first pump main body and a second pump main body, each of the first and second pump main bodies having the top, bottom, and rear walls, a first side opening, and a second side opening, each of the first and second side openings defined between the top, bottom, and rear walls; and assembling a first piston pump by connecting the first crankshaft, the first plurality of pistons, the first pump main body, and a first pair of sidewalls, and assembling a second piston pump by connecting the second crankshaft, the second plurality of pistons, the second pump main body, and a second pair of sidewalls.

These and other aspects and features of various embodiments will be discussed in greater detail below.

Numerous embodiments are described in this application, and are presented for illustrative purposes only. The described embodiments are not intended to be limiting in any sense. The invention is widely applicable to numerous embodiments, as is readily apparent from the disclosure herein. Those skilled in the art will recognize that the present invention may be practiced with modification and alteration without departing from the teachings disclosed herein. Although particular features of the present invention may be described with reference to one or more particular embodiments or figures, it should be understood that such features are not limited to usage in the one or more particular embodiments or figures with reference to which they are described.

The terms “an embodiment,” “embodiment,” “embodiments,” “the embodiment,” “the embodiments,” “one or more embodiments,” “some embodiments,” and “one embodiment” mean “one or more (but not all) embodiments of the present invention(s),” unless expressly specified otherwise.

The terms “including,” “comprising” and variations thereof mean “including but not limited to,” unless expressly specified otherwise. A listing of items does not imply that any or all of the items are mutually exclusive, unless expressly specified otherwise. The terms “a,” “an” and “the” mean “one or more,” unless expressly specified otherwise.

As used herein and in the claims, two or more parts are said to be “coupled”, “connected”, “attached”, “joined”, “affixed”, “secured”, or “fastened” where the parts are joined or operate together either directly or indirectly (i.e., through one or more intermediate parts), so long as a link occurs. As used herein and in the claims, two or more parts are said to be “directly coupled”, “directly connected”, “directly attached”, “directly joined”, “directly affixed”, or “directly fastened” where the parts are connected in physical contact with each other. As used herein, two or more parts are said to be “rigidly coupled”, “rigidly connected”, “rigidly attached”, “rigidly joined”, “rigidly affixed”, or “rigidly fastened” where the parts are coupled so as to move as one while maintaining a constant orientation relative to each other. None of the terms “coupled”, “connected”, “attached”, “joined”, “affixed”, and “fastened” distinguish the manner in which two or more parts are joined together.

Further, although method steps may be described (in the disclosure and/or in the claims) in a sequential order, such methods may be configured to work in alternate orders. In other words, any sequence or order of steps that may be described does not necessarily indicate a requirement that the steps be performed in that order. The steps of methods described herein may be performed in any order that is practical. Further, some steps may be performed simultaneously.

As used herein and in the claims, a group of elements are said to ‘collectively’ perform an act where that act is performed by any one of the elements in the group, or performed cooperatively by two or more (or all) elements in the group.

Some elements herein may be identified by a part number, which is composed of a base number followed by an alphabetical or subscript-numerical suffix (e.g.or). Multiple elements herein may be identified by part numbers that share a base number in common and that differ by their suffixes (e.g.,, and). All elements with a common base number may be referred to collectively or generically using the base number without a suffix (e.g.). For clarity of the drawings, only a first instance or only a few instances of all elements with a common base number may be labelled in the drawings.

The design of existing piston pumps, such as existing linear/reciprocating piston pumps, presents numerous problems in the manufacturability and longevity of the pump. For example, existing piston pumps implement various types of eccentric crankshafts, which are time-intensive, labor-intensive, and thus costly to manufacture. These crankshafts are often made by forging, which requires significant energy consumption. Further, due to their eccentric nature, these crankshafts are subsequently machined using slow, high-energy consumption turning mill methods to produce crankshafts balanced for optimal performance (i.e., to avoid vibration and the resultant failure of the various components of the piston pump). Similarly, other components of existing piston pumps (e.g., connecting rods, pump body) are often made by casting, which also requires significant time investment and energy consumption. The separately cast components may also require transport from the foundry at which they were cast to a common machining facility for subsequent machining.

show a typical piston assemblyof an existing piston pump. The piston assemblyincludes a pistonconnected to an eccentric crankshaftby a connecting rod. As shown, the pistonis commonly a two-piece construction including a piston rodand a plunger. In operation, for each revolution of the eccentric crankshaft, the pistonis moved by the crankshaft, via the connecting rod, between a suction stroke (see e.g.,) and a discharge stroke (see e.g.,). Producing a single suction stroke and discharge stroke for each revolution of the crankshaftmay result in a discontinuous or unsteady discharge of the pumping fluid. Additionally, due to wear of the connecting rodthrough the normal course of operation, the displacement of the pistonin each stroke may decrease over time, resulting in a decrease in a pumping volume of the piston assemblyand thus further degrading pump performance.

During each stroke, the pistonslides through a fluid sealin constant contact with the seal. Due to this contact, the plungeris often made of a ceramic for the high abrasion resistance of ceramic, while a steel piston rodis often used for steel's ability to withstand the forces of the pressurized fluid during the discharge stroke. However, this design requires a perfect seal between the piston rodand the plungerto prevent leaking. Consequently, high precision in manufacturing and assembly of the piston rodand plungeris required, increasing the associated time and cost of manufacture. Further, in the two-piece construction of the piston, the ceramic plungeris connected to the piston rodby a washer and nut, which hold the plungerin compression between the piston rodand the washer and nut. In production, if the nutis tightened too much, the ceramic plungermay crack, leading to leaking through the seal. Conversely, if the nutis not tightened enough, fluid may pass between the plungerand the piston rodand thereby leak through the seal.

Further, as shown in, due to the eccentric nature of the crankshaft, a total force Fof the connecting rodon the pistonduring the suction and discharge strokes includes a pull/push component Falong a longitudinal dimension of the pistonand a downward/upward component Fthat is transverse to the longitudinal dimension of the piston. In standard piston assemblies, such as the piston assemblyshown, the downward/upward component Fmay lead to increased force of contact between the sealand the piston rodand/or plungerduring the suction and discharge strokes. In particular, the downward component Fshown incan reach 20% or more of the total force Fthat is needed to push the pistonagainst the pressurized fluid during the discharge stroke. As a result of the increased force of contact caused by to the downward/upward component F, the piston rod, plunger, and/or sealmay wear at an accelerated rate, leading to premature failure of one or more of these components and leakage of fluid through the seal. Such increased force of contact may also lead to increased vibration during operation of the piston pump and thereby premature failure of the pump body or the components therein.

Referring to, disclosed herein is a piston pump, generally referred to as piston pump, which addresses one or more (or all) of the above-described issues in existing piston pumps. For clarity, embodiments of piston pumpmay address any one or more of the above-described problems, and as such, some embodiments may yet have one or more of the above-described problems unresolved. In some cases, embodiments of piston pumpmay address other problems or have other advantages not described above and have all the above-described problems may remain unresolved. In the illustrated example, the piston pumpincludes a pump housingcontaining a plurality of pistonshaving a piston shaft(better seen e.g., in) and a crankshafthaving a plurality of non-circular cams. As shown, each pistonhas a piston crownresiliently biased to engage a corresponding camsuch that, in operation, the pistonsmay be displaced by rotation of the crankshaftas the portion of the non-circular camwith which the piston crownis engaged changes. It will be appreciated that, while the drawings show only three pistonsand three cams, any number of pistonsand camsmay be used in accordance with this disclosure, which may depend on the size of the piston pumpand/or the desired pumping volume thereof.

The design of the piston pumpmay mitigate or eliminate any one or more (or all) of the issues common to existing piston pumps described previously, including while pumping fluid at high pressures. For example, the use of non-circular cams(e.g., ellipsoid, triangular, square, etc.) increases the number of strokes of the pistonsper revolution of the crankshaft(e.g., 4 strokes, 6 strokes, 8 strokes, etc.), which may provide a steadier discharge of the pumping fluid and/or a greater pumping volume. Additionally, the camsmay have a greater abrasion resistance than the piston crowns, which may result in the piston crownseroding over time. This may prevent or minimize erosion of the cams, which may thereby preserve stroke length of the pistonsand thus preserve pumping volume of the piston pumpthrough time.

As another example, the piston shaftsof the pistonsmay optionally have a unitary design that eliminates the failure modes associated with a typical two-piece piston common in existing piston pumps. Instead of relying on the abrasion resistance of ceramic, the piston shaftsmay have an abrasion-resistance surface treatment providing sufficient abrasion resistance for sliding contact with a fluid seal. Additionally, the total force of the camson the pistonsduring the suction and discharge strokes may remain substantially axially aligned with the piston shaftas the piston shaft reciprocates between suction and discharge strokes. The downward/upward force component that is transverse to the longitudinal dimension of the pistonsmay accordingly be reduced or eliminated. In particular, the downward/upward force component may be less than 10%, or more particularly less than 5%, of the total force needed to push the pistonagainst the pressurized fluid during the discharge stroke. Accordingly, the force of contact between a seal and the piston shaftduring the intake and discharge strokes may be less than that of existing piston pumps, which may decrease vibration of the piston pump, decrease the rate of wear of the piston shafts, and/or decrease the rate of wear of the seals, and thereby extend the service life of piston pumpand these components thereof.

Further, the design of the piston pump, as expanded upon subsequently herein, may be conducive to expeditious mass-production of such piston pumps. For example, any of the pump housing, the cams, the piston crowns, or any other component of the piston pumpmay be manufactured by extrusion, providing fast, repeatable means of mass-producing such piston pumps with a high degree of control of material properties. The time and energy required to produce the piston pumpmay accordingly be less than that required to produce existing piston pumps, and the time and energy may be further reduced per piston pumpwhen mass-produced as described herein.

Referring to, in the illustrated example, the piston pumpshown is a linear piston pump. However, it will be appreciated that the principles of this disclosure may be applied to other reciprocating pumps such as radial pumps and diaphragm pumps, for example.

The pump housingincludes a pump main body. As shown, the pump main bodyhas a top wall, a bottom wallopposite the top wall, and a rear wallextending from and connecting the top wallto the bottom wall. The pump main bodyhas a first side openingand a laterally opposed second side opening. The first and second side openingsshown are defined between the top wall, bottom wall, and rear wall. The pump main bodymay further have a front openingopposite the rear walland defined between the top walland bottom wall.

The pump main bodymay be made of any suitable metal or metal alloy, including one or more of iron, steel, stainless steel, titanium, and aluminum. In the illustrated example, the pump main bodyis made of aluminum. In some embodiments, the profile of the pump main bodymay be manufactured by extrusion, which may advantageously reduce costs of manufacturing, reduce the ecological impact of manufacturing, accelerate both individual production and mass-production of piston pumps, enable the use of many different alloys and fine control of the material properties thereof (e.g., material strength, which may be chosen depending on forces to be experienced by the piston pump and its components during operation, hereinafter the “operational forces”) and, in the case of aluminum and aluminum alloys, enable aluminum anodizing for a range of colors of the pump housing. In other embodiments, none of pump main bodyis manufactured by extrusion.

Referring to, the pump housingfurther includes a first sidewalland a second sidewall. As shown, the first and second sidewallsinclude a central protruding portion. The central protruding portionof the first and second sidewallsmay be shaped to slidably fit in the first and second side openingsbetween the top wall, bottom wall, and rear wall. An advantage of this design is that the central protruding portionmay strengthen the pump main bodyby providing support between the cantilevered top and bottom walls,. Another advantage is that the central protruding portionmay improve the transfer of operational forces between the first and second sidewallsand the pump main body, reducing stress concentration on any one part of the pump housing. In other embodiments, one or both of sidewallsdoes not have a protruding portion.

The first and second sidewallsmay further include a bearing recessshaped for receiving a bearing. The bearingsmay be any size and type suitable for rotatably supporting the crankshaftbetween the first and second sidewalls. As shown, the bearing recessmay be positioned such that, when the central protruding portionsof the first and second sidewallsare inserted into the first and second side openings, the bearingsin the bearing recessesare aligned. In this way, the crankshaftmay extend generally perpendicular to both the first sidewalland the second sidewallwhen rotatably mounted therebetween.

One of the first and second sidewalls, shown as the first sidewallin the illustrated example, may include a crankshaft passagepositioned centrally within the bearing recessesand extending through the sidewall from the bearing recesses. As shown, the crankshaft passagepermits the crankshaftto extend through the first sidewallsuch that rotation of the crankshaftdriven external to the pump housingcan drive rotation of the crankshaftrotatably supported internal to the pump housing.

The first and second sidewallsmay further include a flangebordering the central protruding portionsuch that, when the central protruding portionis inserted into the side opening, the flangeabuts the top wall, bottom wall, and rear wall. As shown, the flangeof the first and second sidewallsis flush with (i.e., does not extend beyond) an outer surface of the pump main body. In alternate embodiments, the flangeof the first and second sidewallsmay extend beyond the outer surface of the pump main body. For example, the flangemay extend downwardly from the bottom wallsuch that the first and second sidewallsmay also function as legs for the piston pump.

The first and second sidewallsmay be connected to the pump main bodyby any suitable means. For example, the first and second sidewallsmay be permanently connected to the pump main body, such as by welding the flangesto the top wall, bottom wall, and rear wall. Alternately, the first and second sidewallsmay be removably connected to the pump main bodyusing any suitable fastener to connect the flangesto the top wall, bottom wall, and rear wall. For example, in the illustrated example, the first and second sidewallsare removably connected to the pump main bodyby a plurality of boltsextending through the flangesand into the top wall, bottom wall, and rear wall. An advantage of removably connecting one or both of the first and second sidewallsto the pump main bodyis that the sidewall(s) may be removed for inspection, maintenance, and/or replacement of the sidewall(s) or any other component of the piston pumpwithin the pump housing. In other embodiments, one or both of sidewallsmay be integrally formed with or permanently joined to pump main body(e.g., by welds or rivets).

Optionally, sidewall sealsmay be positioned between flangesand the pump main bodybefore connecting the first and second sidewallsto the pump main body. The sidewall sealsmay be, for example, any suitable resiliently compressible material (e.g., rubber) that may be compressed between the flangesand the pump main bodywithout splitting/breaking to provide a fluid-tight connection between the sidewallsand the pump main body.

The first and second sidewallsmay be made of any suitable metal or metal alloy, including one or more of iron, steel, stainless steel, titanium, and aluminum. In the illustrated example, the first and second sidewallsare made of steel. The first and second sidewallsmay receive and distribute the operational forces from the crankshaft. Accordingly, steel may be a desirable material for the sidewalls, such as in high-pressure piston pumps, due to its high strength. In other embodiments, one or both sidewallsmay be any other material of suitable strength for handling the operational forces.

While the first and second sidewallsmay be manufactured by any suitable method such as forging or casting, the first and second sidewallsmay be advantageously be manufactured by extrusion. Manufacturing by extrusion may confer similar benefits to those described above with respect to extrusion of the pump main housing. Additionally, manufacturing by extrusion may advantageously enable the production of sidewalls of more uniform thickness and uniform material properties, which may be selected according to the design parameters of the piston pump(e.g., size, operational forces, etc.). In other embodiments, one or both of sidewallsmay be manufactured by means other than extrusion.

Referring still to, the pump housingmay further include a front wallfor closing the front openingof the pump main body. As shown, when the front wallis positioned over the front opening, the front wallmay abut the top wall, bottom wall, and first and second sidewalls. The front wallmay be permanently or removably connected to the pump main bodyusing any suitable means, such as those described with respect to the first and second sidewalls. In the illustrated example, the front wallis removably connected to the pump main bodyby a plurality of boltsextending through the front walland into the top wall, bottom wall, and first and second sidewalls. In other embodiments, the front wallmay be permanently connected to, or integrally formed, the pump main body.

Optionally, the front wallmay include a central protruding portion similar to that of the first and second sidewallsand shaped to slidably fit in the front openingbetween the top wall, bottom wall, and the central protruding portionsof the first and second sidewalls. A central protruding portion of the front wallmay confer similar advantages to those described previously with respect to the central protruding portionof the first and second sidewalls.

Optionally, a front wall sealmay be positioned between the front walland the pump main bodybefore connecting the front wallto the pump main body. The front wall sealmay be, for example, any suitable resiliently compressible material (e.g., rubber) that may be compressed between the front walland the pump main bodywithout splitting/breaking to provide a fluid-tight connection between the front walland the pump main body.

The front wallmay be made of any suitable metal or metal alloy, including one or more of iron, steel, stainless steel, titanium, and aluminum. In the illustrated example, the front wallis made of aluminum. While the front wallmay be manufactured by any suitable method such as forging or casting, the front wallmay be advantageously manufactured by extrusion, which may confer similar benefits to those described above with respect to extrusion of the pump main housing. Optionally, where the pump main bodyand the front wallare the same material, the pump main bodymay be extruded with the front wallsuch that the pump main bodyis integrally formed therewith. In such examples, the central protruding portionof the first and second sidewallsmay be shaped to slidably fit in the first and second openingdefined between the top wall, bottom wall, rear wall, and front wall, and the flangeof the first and second sidewallsmay be connected to the top wall, bottom wall, rear wall, and front wallas described previously. In other embodiments, the front wallmay be manufactured by means other than extrusion.

Referring to, when the first and second sidewallsand the front wallare connected to the pump main body, the pump housingmay include a crankshaft chamberdefined between the top wall, bottom wall, rear wall, first and second sidewalls, and front wall. As shown, the crankshaftmay be rotatably mounted within the crankshaft chambervia bearingsas described previously. Any other means suitable for rotatably mounting the crankshaftwithin the crankshaft chambermay be used.

Referring still toand additionally to, the pump housingmay further include a plurality of piston passages. As shown, the pistons passagesmay extend through the rear wallof the pump main body. Each of the piston passagesmay have one of the pistonsslidably mounted therein. In manufacturing the piston pump, the piston passagesmay be machined (e.g., drilled) through the rear wallsubsequent to the forming of the pump main housing, whether by forging, casting, or extrusion. In other embodiments, the piston passagesmay be formed at the same time as the forming of the pump main housing.

The pump housingmay further have a pumping chamberdefined within a pumping chamber housing. As shown, the pumping chamber housingmay be connected to the rear wallof the pump main body. In this way, the pumping chambermay be spaced apart from the crankshaft chamberby the rear wall. Consequently, the piston passagesmay extend from the crankshaft chamberto the pumping chamber. The pumping chamber housingmay be connected to the pump main bodyby any suitable means. For example, pumping chamber housingmay be permanently connected to the pump main body, such as by welding to the rear wall. Alternately, pumping chamber housingmay be removably connected to the pump main bodyusing any suitable fastener. For example, as shown in the illustrated example, the pumping chamber housingmay be removably connected to the pump main bodyby a plurality of boltsextending into the rear wall. An advantage of removably connecting pumping chamber housingto the pump main bodyis that pumping chamber housingmay be removed for inspection, maintenance, and/or replacement of the components within the pumping chamber. In alternate embodiments, the pumping chamber housingmay be permanently connected to, or integrally formed with, the pump housing.

The pumping chambermay be subdivided into a plurality of working chambers. Each working chambermay include a piston openingwhich, when the pumping chamber housingis connected to the pump main body, may align with a corresponding one of the piston passages. In this way, each pistonmay extend into one of the working chambersfrom the piston passagewith which that working chamberis aligned and in which the pistonis slidably mounted. In other embodiments, such as where the pumping chamber housingis integrally formed with the pump housing, the working chambersand the piston passagemay similarly be integrally formed.

As shown in the illustrated example, each working chambermay further include a fluid intake port, through which fluid may be drawn into the working chamber, and a fluid outlet port, through which fluid may be discharged from the working chamber. The intake portmay include a non-return intake valve(e.g., a check valve) and the outlet portincludes a non-return outlet valve(e.g., a check valve). In operation, during the suction stroke wherein the pistonis withdrawn from the working chamber, the non-return intake valveof the intake portmay be open and the non-return outlet valveof the outlet portmay be closed. In this way, fluid may be drawn into the working chamberduring the suction stroke. Conversely, during the discharge stroke wherein the pistonis driven into the working chamber, the non-return intake valveof the intake portmay be closed and the non-return outlet valveof the outlet portmay be open. In this way, fluid may be expelled from the working chamberduring the discharge stroke.

Referring still to, in the illustrated example, the crankshaftof the piston pumpincludes a crankshaft axlerotatably mounted within the crankshaft chamberabout a longitudinally extending crankshaft rotation axis. As shown, the crankshaft axlemay be rotatably mounted via the bearings. The bearingsmay be positioned as described previously such that the crankshaft axisextends generally perpendicularly to the first and second sidewalls. Consequently, crankshaft axismay extend generally parallel to the rear wall. In this way, the crankshaft axlemay have a constant spacing from the rear wallacross the crankshaft chamber. Similarly, the non-circular camsof the crankshaftmay be connected to the crankshaft axleand distributed along the crankshaft axissuch that, when the crankshaft axleis mounted in the crankshaft chamber, each camis aligned with one of the piston passagesand the camsmay be equidistant from their respective piston passages(i.e., when the camshave the same orientation). An advantage of this design is that the operational forces on the crankshaft(e.g., from resilient biases, pressurized pumping fluid) may be more evenly distributed across the crankshaft axleand more evenly transferred to the first and second sidewalls. This may avoid uneven stress concentrations (e.g., in the crankshaft axle, bearings, sidewalls) that may otherwise lead to premature failure of the components of the piston pump. In other embodiments, the crankshaft axlemay be rotatably mounted within the crankshaft chambersuch that the crankshaft axisextends at an angle to the first and second sidewallsand/or to the rear wall.

The crankshaft axlemay be made of any suitable metal or metal alloy, including one or more of iron, steel, stainless steel, titanium, and aluminum. In the illustrated example, the crankshaft axleis made of steel, which may be advantageous for transferring operational forces from the pistonsto the first and second sidewallsdue to the high strength of steel. In other embodiments, the crankshaft axlemay be any other material having any suitable diameter for providing the requisite strength for transferring operational forces. The crankshaft axlemay be manufactured by any suitable method such as forging, casting, or extrusion, or may be machined from a round stock rod of suitable diameter.

Referring to, shown therein are various examples of non-circular camsof the crankshaft. As shown, each cammay have a central openingsized to receive the crankshaft axlesuch that each camis slidably removably connectable to the crankshaft axlethrough the central opening. After slidably connecting to the crankshaft axle, the camscan be rigidly connected to the crankshaft axleby any suitable means, such as by one or more fasteners (e.g., screw, bolt), or welding. Connecting (e.g., rigidly) the camsto the crankshaft axlemay inhibit the camsfrom rotating relative to the crankshaft axleabout the crankshaft axis. Connecting the camsto the crankshaft axlemay further inhibit the camsfrom sliding on the crankshaft axlealong the crankshaft axis. In other embodiments, the camsmay be connected to the crankshaft axleby different means. For example, the camsmay be integrally formed with the crankshaft axle(e.g., machined in) or the camsmay each be a two-piece construction that may be connected around the crankshaft axleat the desired position.

Additionally, or in the alternative, as exemplified in to, the crankshaftmay optionally include a plurality of cam securement pinsdistributed along the crankshaft axisand extending radially outwardly from the crankshaft axle, and the central openingof the camsmay include a cam lock recessshaped to slidably mate with one of the cam securement pins. In this way, when each camis slidably connected to the crankshaft axle, the cam lock recessmay slidably mate with one of the cam securement pins. The cam securement pinsmay thus rigidly connect the mating camsto the crankshaft axlesuch that the camsmay be inhibited from rotating relative to the crankshaft axleabout the crankshaft axis. An advantage of the cam securement pinsand cam lock recessesis that the camsmay be removably rigidly connected to the crankshaft axlesuch that the camsmay be removed for replacement (e.g., at the end of service life of the cam). Another advantage is that differently shaped camsmay be used interchangeably in the same piston pump(e.g., to change pump operation, such as pumping volume). In other embodiments, crankshaftdoes not include cam securement pins.

The cam securement pinsmay be connected to the crankshaft axleby any suitable means (e.g., welding). In the example shown in, the crankshaft axleincludes a plurality of securement pin recessesdistributed along the crankshaft axisand extending radially inwardly into the crankshaft axle. The cam securement pinsmay be connected to the crankshaft axleby insertion into the securement pin recessesand held in a friction fit within the securement pin recessesor, optionally, secured in the securement pin recessessuch as by adhesive, welding, or fasteners. In other embodiments, crankshaft axledoes not include securement pin recesses.