CN217813773U - Combined axial piston pump - Google Patents

Abstract

A composite axial piston pump, a plurality of axial piston pumps connected together along a common drive axis, the axial piston pump comprising: a pump housing, a pump shaft extending through the pump housing along a common drive axis and into the housing cavity; the cylinder is fixed to the pump shaft and includes a plurality of cylinders; a plurality of pistons, a swash plate fixed to the pump housing and configured to reciprocate the pistons. A valve plate and a port block are connected to the pump housing and in fluid communication with the cylinders, the valve plate configured to direct fluid flow from a suction port defined in the port block to the plurality of cylinders, the cylinders directed to a discharge port defined in the port block. The plurality of axial piston pumps are connected together such that a suction port defined in a port block of at least one of the pumps is directed vertically downward and is configured to be in fluid connection with a straight suction port line oriented vertically upward from below the pump.

Description

Combined axial piston pump

Technical Field

The present invention relates generally to a combination of axial piston pumps, and more particularly to an arrangement of axial piston pumps connected together and driven along a common drive axis, wherein the pumps are each oriented such that their inlet fluid lines extend linearly out from the bottom of each pump.

Background

Axial piston pumps are known for use in hydraulically actuated fuel injection systems and in other applications including implement pumps, swing pumps, oil cooler pumps, fan pumps, pilot pumps, etc. for heavy machinery. Efficient operation of such pumps is important to the overall operation of the engine. Furthermore, the maintenance-free operation capability of such pumps is important to reduce system downtime. While efficient operation is an important design criterion, issues such as weight, size, cost, installation limitations, flow rate, potential pump cavitation, and ease of assembly impact the overall design of such pumps.

U.S. Pat. No. 6,035,828 to Anderson et al describes a fixed displacement, variable flow axial piston pump for a hydraulically actuated fuel injection system. In this system, a high pressure common rail supplies hydraulic fluid to a plurality of hydraulically actuated fuel injectors mounted in a diesel engine. The hydraulic fluid contained in the common rail is pressurized by a fixed displacement axial piston pump that is directly driven by the engine. The pump includes a plurality of pistons arranged in parallel about a central longitudinal axis of the pump, and reciprocation of the pistons is effected by rotation of an inclined cam surface or swash plate biased against the proximal ends of the pistons. The displacement of the pump is varied by a control valve that selectively varies the amount of pressurized fluid supplied to the pump outlet during the discharge stroke of each piston.

In the case of an axial hydraulic piston pump, the central cylinder or block is rotatably driven by an engine or other motor. The barrel includes a plurality of cylinders, each cylinder adapted to receive a reciprocating piston. At the driven end, each piston is pivotally and slidably engaged with a swash plate positioned at an angle relative to the cylinder barrel. At the working end of each cylinder, a valve plate having two or more kidney-shaped inlets and outlets is provided. During the inlet phase of operation, hydraulic fluid is drawn through the inlet of the valve plate and into the cylinder of the rotating cylinder. This pumping or filling of the cylinder takes place as the cylinder rotates and the piston of the cylinder, which is close to the inlet, moves from the top dead centre position to the bottom dead centre position. The rotation of the cylinder and the dimensions of the inlet are such that the cylinder rotates out of communication with the inlet of the valve plate once the piston reaches its bottom dead center position. As the piston moves from the bottom dead center position to the top dead center position, further rotation of the barrel causes fluid flow to the cylinder, which is now completely filled with hydraulic fluid. During travel from the bottom dead center to the top dead center position, the cylinder communicates with the outlet of the valve plate so that hydraulic fluid can be delivered from the pump to provide useful work as described above or to provide for the driving of implements and work arms on various earth moving equipment.

While the pump of Anderson et al may be adequate for certain applications, there remains a need for an axial piston pump and combination of axial piston pumps that are specifically designed for certain applications, particularly on heavy equipment, where the pumps are mounted together along a common drive axis to meet space constraints and utilize available drives on the heavy equipment, such as gearboxes, and have specific performance dimensions, port dimensions, ranges of positions and orientations of ports, and overall configurations determined by extensive analysis, including application of physics-based equations, flow rate analysis, and other computational fluid dynamics simulations, taking into account the flow rates required for higher speed operation, while avoiding phenomena that can increase wear on the pumps and shorten their service life. Some applications require unique sizes and arrangements of suction and discharge ports to meet system installation constraints.

SUMMERY OF THE UTILITY MODEL

The utility model provides a modular axial piston pump, it has overcome prior art's shortcoming to satisfy the specific performance and the constructional requirement of certain system and functional requirement of certain heavy equipment.

A combined axial piston pump comprising a combination of a plurality of axial piston pumps connected together along a common drive axis, wherein the axial piston pumps each comprise: a pump housing having a central longitudinal axis and a housing cavity; a rotatable pump shaft extending through the pump housing along the common drive axis and into the housing chamber; a cylinder fixed to the pump shaft and including a plurality of cylinders; a plurality of pistons configured for reciprocating movement within a cylinder; and a swash plate fixed to the pump housing and configured to reciprocate the pistons such that capacity chambers of the cylinders expand and contract as the pump shaft and the cylinder body rotate; a valve plate; and a port block connected to or integral with the pump housing and in fluid communication with the cylinder; the valve plate is configured to direct fluid flow from a suction port defined in the port block to the plurality of cylinders and from the cylinders to a discharge port defined in the port block; and

the plurality of axial piston pumps are connected together such that a suction port defined in a port block of at least one of the axial piston pumps is directed vertically downward and is configured to be in fluid connection with a straight suction port line oriented vertically upward from below the axial piston pump.

A first axial piston pump of the combination of the plurality of axial piston pumps comprises a flange on a rear surface of the first axial piston pump having a distributed configuration of bolt holes configured to connect a second axial piston pump to the rear surface of the first axial piston pump, wherein the suction ports are defined in a port block of the second axial piston pump, oriented vertically downward and configured to fluidly connect with a straight suction port line oriented vertically upward from below the second axial piston pump.

A second axial piston pump of the combination of the plurality of axial piston pumps comprises a flange on a rear surface of the second axial piston pump having a distributed arrangement of bolt holes capable of connecting a third axial piston pump to the rear surface of the second axial piston pump, wherein the suction ports are defined in a port block of the third axial piston pump, oriented vertically downward and configured to be in fluid connection with a straight suction port line oriented vertically upward from below the third axial piston pump.

A first axial piston pump of the combination of the plurality of axial piston pumps comprises a flange on a rear surface of the first axial piston pump having a distribution of bolt holes configured to connect a second axial piston pump to the rear surface of the first axial piston pump, the suction port being defined in a port block of the second axial piston pump, oriented vertically downward and configured to fluidly connect with a straight suction port line oriented vertically upward from below the second axial piston pump, and wherein the second axial piston pump of the combination of the plurality of axial piston pumps comprises a flange on a rear surface of the second axial piston pump having a distribution of bolt holes configured to connect a third axial piston pump to the rear surface of the second axial pump, wherein the suction port is defined in a port block of the third axial piston pump, oriented vertically downward and configured to fluidly connect with a suction port line oriented vertically upward from below the third axial piston pump.

Each of the axial piston pumps includes a respective discharge port defined in the port block of the axial piston pump, the discharge ports being oriented 180 degrees from the suction port and on opposite sides of the port block.

Each of the axial piston pumps includes a respective discharge port defined in the port block of the axial piston pump, the discharge ports being oriented 180 degrees from the suction port and on opposite sides of the port block.

Each of the axial piston pumps includes a respective discharge port defined in the port block of the axial piston pump, the discharge ports being oriented 180 degrees from the suction port and on opposite sides of the port block.

Each of the axial piston pumps includes a respective discharge port defined in the port block of the axial piston pump, the discharge ports being oriented 180 degrees from the suction port and on opposite sides of the port block.

The respective discharge port is configured to fluidly connect with an elbow that redirects fluid flow discharged from the respective discharge port.

A combined axial piston pump comprising a combination of three axial piston pumps connected together along a common drive axis, wherein the axial piston pumps each comprise: a pump housing having a central longitudinal axis and a housing cavity; a rotatable pump shaft extending through the pump housing along the common drive axis and into the housing chamber; a barrel fixed to the pump shaft and including a plurality of cylinders; a plurality of pistons configured for reciprocating movement within a cylinder; and a swash plate fixed to the pump housing and configured to reciprocate the pistons such that capacity chambers of the cylinders expand and contract as the cylinder body rotates; a valve plate; and a port block connected to or integral with the pump housing and in fluid communication with the cylinder; the valve plate is configured to direct fluid flow from a suction port defined in the port block to the plurality of cylinders and from the cylinders to a discharge port defined in the port block; and

the three axial piston pumps are connected together such that the suction ports defined in the port blocks of at least two of the axial piston pumps are directed vertically downwards and are configured to be in fluid connection with a straight suction port line oriented vertically upwards from below the axial piston pumps.

According to an aspect of the invention, two or more axial piston pumps in combination are connected together along a common drive axis, wherein the axial piston pumps each comprise: a pump housing having a central longitudinal axis and a housing cavity; a rotatable pump shaft extending through the pump housing along the common drive axis and into the housing chamber; a rotating cylinder fixed to the pump shaft and including a plurality of cylinders; a plurality of pump pistons configured for reciprocating movement within the plurality of cylinders; and a swash plate fixed to the pump housing and configured to reciprocate the pump pistons such that capacity chambers of the cylinders expand and contract as the cylinder body rotates. Each pump further comprises a valve plate and a port block connected to or integral with the pump housing and in fluid communication with the cylinder. The valve plate is configured to direct fluid flow from a suction port defined in the port block to the plurality of cylinders and from the cylinders to a discharge port defined in the port block. The two or more axial piston pumps are connected together such that a suction port defined in a port block of at least one of the pumps is directed vertically downward and is configured to be in fluid connection with a straight suction port line oriented vertically upward from below the pump.

According to another aspect of the invention, three axial piston pumps in combination are connected together along a common drive axis, wherein the axial piston pumps each comprise: a pump housing having a central longitudinal axis and a housing cavity; a rotatable pump shaft extending through the pump housing along the common drive axis and into the housing chamber; a rotating cylinder fixed to the pump shaft and including a plurality of cylinders; a plurality of pump pistons configured for reciprocating movement within the plurality of cylinders; and a swash plate fixed to the pump housing and configured to reciprocate the pump pistons such that capacity chambers of the cylinders expand and contract as the cylinder body rotates. Each pump further comprises a valve plate and a port block connected to or integral with the pump housing and in fluid communication with the cylinder. The valve plate is configured to direct fluid flow from a suction port defined in the port block to the plurality of cylinders and from the cylinders to a discharge port defined in the port block. The three axial piston pumps are connected together such that a suction port defined in a port block of each of the pumps is directed vertically downward and configured to be in fluid connection with a straight suction port line oriented vertically upward from below the pumps.

The utility model discloses to the improvement of axial piston pump entry structure, can avoid latent pump gas pocket phenomenon, improve life, along common drive axis mounting means, satisfied the adaptability demand of joining in marriage the dress with the machine.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several exemplary embodiments of the invention and together with the description, serve to explain the principles and aspects of the invention.

Drawings

Fig. 1 is a side view of a combined axial piston pump according to an exemplary embodiment of the present invention;

fig. 2A and 2B are perspective views of the combined axial piston pump shown in fig. 1.

Fig. 3 is a rear view of a flange interface between the two axial piston pumps of fig. 1 and 2A, 2B.

FIG. 4 is a rear view of the combination axial piston pump shown in FIG. 1 and FIGS. 2A and 2B; and

FIG. 5 is a longitudinal cross-sectional view of an exemplary axial piston pump such as may be included in the combined axial piston pump of FIG. 1.

Detailed Description

Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

Fig. 1-4 illustrate an exemplary combination 100 of axial piston pumps connected together along a common drive axis for various applications on heavy equipment such as earth moving machinery. As shown in fig. 1-4, the first pump 120 may be an axial piston pump configured to function as a swing pump or other implement pump used on heavy equipment, such as an excavator, the second pump 130 is bolted to a flange 124 on a rear side of the first pump 120 and configured to function as an oil cooler or fan pump, and the third pump 140 is bolted to a rear side of the second pump 130 and configured to function as a pilot pump. The function of each of a plurality of axial piston pumps that may be coupled together according to embodiments of the present invention may differ from the functions listed above. As shown in fig. 3, the flange 124 on the rear side of the first pump 120 may be provided with an arrangement of bolt holes 320, 322, 324, and 326, the bolt holes 320, 322, 324, and 326 configured to receive bolts that connect the second pump 130 to the rear side of the first pump 120. According to various exemplary embodiments of the present invention, the bolt pattern in the flange 124 for connecting the third pump 140 and in the flange on the rear side of the second pump 130 may be configured such that the fluid inlet connectors 160, 180 guiding fluid into the inlet suction ports of the pumps are positioned at the bottom side of the pumps 130, 140, respectively, thereby enabling direct vertical fluid flow paths 162, 182 for delivering fluid into the pumps 130, 140, respectively. The direct fluid flow path into the fluid inlet connector of the axial piston pump on the low pressure suction side of the pump avoids any restriction to inlet fluid flow on the low pressure suction side of each pump and also avoids potential pump cavitation.

When the combined flow rate and pressure in the pump is insufficient or detrimental to the type of liquid being pumped, pump cavitation can occur, resulting in the formation of air pockets or air cavities in the fluid, resulting in cavitation. These air cavities or air chambers can collapse or implode quickly with great force, thereby generating rapid and energy release from the implosion of the air chambers, potentially leading to wear and premature failure of the pump. The restricted inlet flow path, which may be created, for example, by an elbow or other fluid inlet connector, may result in a change in the direction of flow or a change in the cross-sectional area of flow of the fluid supplied to the axial piston pump, which may result in a change in the fluid flow rate or pressure at the suction port of the pump, thereby contributing to potential pump cavitation caused by the creation and collapse of air pockets or air cavities.

As shown in the arrangement and orientation of the exemplary axial piston pumps 120, 130 and 140 shown in fig. 1, 2A, 2B and 4, the bolt pattern on the flange 124 on the rear side of the first pump 120 is configured such that the second pump 130 can be connected to the rear side of the first pump 120 with the fluid inlet connector 160 for the second pump 130 directed vertically downward and the third pump 140 connected to the rear side of the second pump 130 with the fluid inlet connector 180 for the third pump 140 directed vertically downward, allowing multiple pumps to be installed along a common drive axis while avoiding any unnecessary restriction to fluid flow on the low pressure inlet side of the pumps.

Referring now to FIG. 5, an exemplary axial piston pump that may be connected together with one or more other axial piston pumps of similar design to form an assembly of multiple axial piston pumps that may be driven along a common drive axis is indicated by reference numeral 220. As shown in FIG. 5, the pump 220 includes an outer housing or casing 222 from which a drive shaft 224 extends for connection to the transmission and engine of the larger machine on which the pump is positioned. As shown in fig. 1-4, the pump 220 may be an example of a type of axial piston pump 120, 130, 140, which axial piston pumps 120, 130, 140 may be connected together in a pump assembly driven along a common drive axis. In the exemplary embodiment of fig. 1, as described above, the first axial piston pump 120 may be a swing pump or other implement pump for supplying pressurized hydraulic fluid, for example, to a swing arm of an excavator, the second axial piston pump 130 may be an oil cooler or fan pump for pumping hydraulic fluid, for example, through a radiator, driving a fan or operating another cooling source, wherein the oil cooler pump 130 is connected to a flange 124 on the rear side of the first axial piston pump 120, and the third axial piston pump 140 may be a pilot pump or other pump for supplying pressurized hydraulic fluid for another function. As shown in fig. 1, pumps 120, 130, and 140 may be connected together along a common drive axis for a variety of reasons, including but not limited to saving space on the machine, and the availability of drives, such as gear boxes and drive shafts, that are configured to provide drive power to the plurality of pumps.

The example axial piston pump 220 may be designed to draw hydraulic fluid through an inlet 226 in the port block 288 and discharge the hydraulic fluid through an outlet 228 in the port block 288 (see fig. 5) to communicate with an implement, actuator, or other component on the machine that converts pressure from the pressurized hydraulic fluid into work required to perform various functions. In some alternative embodiments of the exemplary axial piston pump 220, the port block 288 (which may also be referred to as a "head") may be replaced with a component such as a port block or a combination of a head and a back cover of the axial piston pump. The drive shaft 224 may be operably connected to a barrel 230 (e.g., interconnected by splines) adapted to rotate within the housing 222. The cylinder 230 is positioned adjacent a valve plate 232, the valve plate 232 including fluid flow apertures in fluid communication with the aforementioned inlet 226 and outlet 228 formed in a port block 288.

Referring also to fig. 5, the cartridge 230 is shown in greater detail. The cartridge 230 may include a cylinder block 234 with a plurality of cylinders 236 in the cylinder block 234. Each cylinder 236 is parallel and includes a cylinder wall 238. A piston 240 is mounted for reciprocal movement within each cylinder 236. More specifically, each piston 240 is adapted to reciprocate within the cylinder 236 as the piston 240 and cylinder barrel 230 rotate about a central longitudinal axis 246 of the pump 220 through inlet and outlet strokes.

To reciprocate the pistons 240 through the cylinders 236, the driven end 242 of each piston is rotatably and slidably engaged with a swash plate 244 via a slide block 245. The swash plate 244 may be disposed at a transverse angle relative to the cylinder barrel 230 such that the pistons 240 reciprocate back and forth therein as the cylinder barrel 230 and pistons 240 rotate about a longitudinal axis 246 under the influence of hydraulic fluid entering and exiting the cylinders 236. Further, the angle at which the swashplate 244 is positioned determines the resulting volume of fluid flow from the pump 220. For example, if the swash plate 244 is parallel to the valve plate 232, there is no fluid flow at all. However, at each angle, the swash plate 244 pivots away from parallel, and the resulting flow of exhaust fluid increases.

Opposite the driven end 242, each piston 240 includes a working end 248. As also shown in fig. 5, the working end 248 is adapted to reciprocate between a bottom dead center position 249 and a top dead center position 251. As one of ordinary skill in the art will appreciate, during the filling or intake stroke of each piston 240, the working end 248 moves from the top dead center position 251 to the bottom dead center position 249; and during the exhaust stroke the working end 248 moves from the bottom dead center position 249 to the top dead center position 251.

Hydraulic fluid drawn during the intake stroke and expelled during the exhaust stroke may be directed through the plurality of fluid flow apertures 250 shown in fig. 5. In some exemplary embodiments, the transverse cross-sectional shape of each fluid flow aperture may be substantially elliptical and may include a plurality of facets and angles to facilitate inflow and outflow and, therefore, the overall throughput of the pump 220.

Each fluid flow bore 250 may include a plurality of surfaces angled at particular sizes and angles to most effectively fill and drain hydraulic fluid. For example, each cylinder 236 may terminate in a front chamber 252, the front chamber 252 having a front chamber wall 254 concentric with the cylinder wall 238, but having a slightly smaller diameter. The walls of the front chamber 252 lead to a first output engagement wall 256 disposed at a transverse angle relative to the front chamber wall 254.

The first output engagement wall 256 may then extend into a second output engagement wall 260 disposed at an angle to the first output engagement wall 256. The first and second output engagement walls 256 and 260, respectively, may not be planar in shape, but rather curved according to the general kidney shape (specifically, compound kidney shape) of the fluid flow aperture 250. The fluid flow aperture 250 may also be defined by a first input engagement wall 264 disposed at a transverse angle relative to the front chamber wall 254. Each cylinder 236, antechamber 252 and fluid flow bore 250 cooperate to define an inlet fluid flow path that may not be linear in direction, but rather a curve having multiple angular portions. In operation, during an input stroke of the piston 240, the fluid flow path begins in the portion where hydraulic fluid is drawn through the fluid flow apertures 250 in a direction parallel to the longitudinal axis 246 but laterally offset from the cylinder 236, and then radially outward until it enters the front chamber 252 whereupon the fluid enters the cylinder 236. During the output stroke, a fluid flow path is created in which the compressed fluid moves through the cylinder 236 until reaching the front chamber, where the compressed fluid moves parallel to the cylinder 236 and concentric with the cylinder 236. The compressed fluid then engages the first output engagement wall 256, where it is directed radially inward until redirected by the second output engagement wall 260 cooperating with the second input engagement wall 268, and the fluid thereby exits the cylinder block 234.

The fluid flow bore 250 cooperates with the valve plate 232 and the port block 288 to draw hydraulic fluid through the inlet 226 and direct hydraulic fluid out through the outlet 228. In an exemplary embodiment, the valve plate 232 may include one curved or kidney-shaped inlet aperture and first and second curved or kidney-shaped outlet apertures. Each of the inlet and outlet apertures in the valve plate 232 may be configured to be curvilinear or kidney-shaped to facilitate communication of hydraulic fluid as the cylinder block 234 and cylinder 236 rotate relative to the valve plate 232. More specifically, because valve plate 232 is secured within pump 220 as cartridge 230 rotates, fluid communication can be achieved during such rotation by providing valve plate 232 with kidney-shaped inlet and outlet apertures. The inlet aperture may be configured to traverse more than 90 degrees but less than 180 degrees around the valve plate 232. In another aspect, each outlet aperture may be less than 90 degrees laterally around valve plate 232. This is done to provide an effective transition between the inlet 226 and the outlet 228 in the port block 288 and between the suction and compression strokes.

As described above, each piston 240 reciprocates away from valve plate 232 through its associated cylinder 236 from top dead center position 251 to bottom dead center position 249 during an intake stroke. Upon reaching the bottom dead center position 249, the cylinder 236 is completely filled with hydraulic fluid, and therefore fluid communication of the hydraulic fluid supply must be stopped and the full cylinder 236 continued to rotate toward the outlet orifice in the valve plate 232. However, before doing so, the transition zone of the valve plate 32 remains interrupted of fluid flow, allowing each piston 240 to reverse direction and begin compressing fluid as the piston 240 moves from the bottom dead center position 249 to the top dead center position 251. As it rotates through the first and second outlet apertures in valve plate 232, the fluid in each cylinder 236 is expelled due to the change in displacement of each associated piston 240, and the pistons 240 again approach top dead center positions 251.

In various alternative embodiments according to the present invention, the suction inlet 226 in the port block 288 may be configured to terminate on an outer surface of the port block at a suction port having a predetermined specific diameter to meet specific performance requirements of the machine on which the axial piston pump is mounted. Some exemplary performance requirements for a particular machine and application may include improved pump inlet conditions, higher speed pump operation, greater fluid volumetric flow, and avoidance of any potential pump cavitation that may be caused by a disruption or restriction in inlet flow or a reduction in inlet pressure. In some exemplary embodiments, an axial piston pump used as an implement pump may be designed to provide fluid flow rates of, for example, 280 cc/sec or greater, and may be used in large wheel loaders, such as large wheel loaders of carter peller 990, 993, and 994. In such applications, the suction port may be 5 inches ± 0.25 inches in diameter, and the porting block may be configured such that the suction port is positioned on one side of the porting block at 180 degrees from the discharge port on the opposite side of the porting block. In other alternative embodiments, the diameter of the suction port may be 3.5 inches ± 0.25 inches, or 4.0 inches ± 0.25 inches, depending on the particular application, system installation and connection constraints, machine configuration, and other factors. In addition, alternative embodiments may position the inlet suction port on one side of the porting block, or on the rear of the porting block, with the discharge port defined as having a central axis that is perpendicular to the central axis of the suction port, extending vertically through the bottom of the porting block, or extending horizontally through one side of the porting block, or having a central axis of the discharge port that extends 180 degrees from the central axis of the suction port, for example, through the side of the porting block opposite the suction port. Various exemplary embodiments of a port block for an axial piston pump according to the present invention, and the diameter, orientation and relative positioning of inlet suction and discharge ports on one or more axial piston pumps in an assembly of multiple axial piston pumps, may be selected according to particular performance requirements, flow factors, avoidance of pump cavitation, installation and system installation constraints of the pump on a particular machine and available drive source, ease of manufacturability, and other considerations.

Industrial applicability

In operation, the axial piston pump 220 may be mounted on the machine alone, or in some embodiments according to the present disclosure, the axial piston pump 220 may be mounted on the machine. Two or more axial piston pumps of the same or similar design may be coupled together along a common drive axis and oriented relative to each other such that when the pumps are assembled together and mounted on a machine, the inlet suction port on each pump is configured to face vertically downward to facilitate mounting a straight fluid connection extending vertically into the bottom of each pump without bends or other potential restrictions to inlet fluid flow. Factors that determine how many axial piston pumps can be stacked together and mounted to the machine along a common drive axis can include space limitations on the machine, available drives (e.g., gear boxes) and drive connections on the machine (which can be used to drive connections on the drive shaft 224), and pressurized hydraulic fluid requirements on a particular machine.

As best seen in fig. 1-3, the bolt pattern on the flange 124 on the rear side of the first pump 120 of the pump combination 100 may be configured such that the second pump 130 may be coupled to the rear side of the first pump 120 with the fluid inlet connector 160 for the second pump 130 directed vertically downward, and such that the third pump 140 is coupled to the rear side of the second pump 130 with the fluid inlet connector 180 for the third pump 140 directed vertically downward. The mounting arrangement described above allows multiple pumps to be mounted along a common drive axis on the machine, whilst avoiding any unnecessary restriction to fluid flow on the low pressure inlet side of the pumps. The bolt pattern on the flange 124 on the rear side of the first pump 120 of the pump assembly 100 is an example of a bolt pattern that enables additional pumps coupled to the first pump to be oppositely oriented along a common drive axis when the pumps are mounted on a machine such that the vertical fluid flow paths 162, 182 direct low pressure fluid in the pumps to be pressurized into and through the suction inlets.

Each axial piston pump may be designed to draw hydraulic fluid through an inlet 226 formed in a side or rear surface of the port block 288 or through an inlet 226 formed by an additional portion such as a cap coupled to the rear surface of the port block and discharge the hydraulic fluid through an outlet 228 or discharge port formed in a side or bottom surface of the port block 288 at an angle, for example, of 90 degrees or 180 degrees (see fig. 5) relative to a central axis of the suction port for communication with implements, actuators, or other components on the machine, converting pressure from the pressurized hydraulic fluid into work required to perform various functions. The drive shaft 224 of the axial piston pump may be operatively connected to a cylinder (or block) 230 (e.g., via a splined interconnection), the cylinder (or block) 230 being adapted to rotate within the pump housing 222. The cartridge 230 may be positioned adjacent a valve plate 232, the valve plate 232 including fluid flow apertures, such as arcuate slots extending circumferentially therethrough, in fluid communication with the aforementioned inlet 226 and outlet 228 formed in a port block 288.

Referring also to fig. 5, and as noted above, the cartridge 230 is shown in greater detail. The cylinder 230 may include a cylinder block 234, and a plurality of cylinders 236 are disposed in the cylinder block 234. Each cylinder 236 is parallel and includes a cylinder wall 238. A piston 240 is mounted for reciprocating movement within each cylinder 236. More specifically, each piston 240 is adapted to reciprocate within the cylinder 236 as the piston 240 and cylinder barrel 230 rotate about a central longitudinal axis 246 of the pump 220 through intake and exhaust strokes.

To reciprocate the pistons 240 through the cylinders 236 to vary the chamber volume in each cylinder as fluid is drawn into, compressed in, and discharged from each cylinder, the driven end 242 of each piston is rotatably and slidably engaged with a swash plate 244 by a slide 245. The swash plate 244 may be disposed at a transverse angle relative to the cylinder barrel 230 such that the pistons 240 reciprocate back and forth therein as the cylinder barrel 230 and pistons 240 rotate about a longitudinal axis 246 under the influence of hydraulic fluid entering and exiting the cylinders 236. Further, the angle at which the swashplate 244 is positioned determines the resulting volume of fluid flow from the pump 220. For example, if the swash plate 244 is parallel to the valve plate 232, there is no fluid flow at all. However, at each angle, the swash plate 244 pivots away from parallel, and the resulting flow of exhaust fluid increases.

Opposite the driven end 242, each piston 240 includes a working end 248. As also shown in fig. 5, the working end 248 is adapted to reciprocate between a bottom dead center position 249 and a top dead center position 251. As will be appreciated by one of ordinary skill in the art, during the filling or intake stroke of each piston 240, the working end 248 moves from the top dead center position 251 to the bottom dead center position 249; and during the exhaust stroke the working end 248 moves from the bottom dead center position 249 to the top dead center position 251. As shown in the arrangement and orientation of the example axial piston pumps 120, 130 and 140 shown in fig. 1, 2A, 2B and 4, the bolt pattern on the flange 124 on the rear side of the first pump 120 is configured such that the second pump 130 can be coupled to the rear side of the first pump 120 with the fluid inlet connector 160 for the second pump 130 pointing vertically downward and the third pump 140 coupled to the rear side of the second pump 130 with the fluid inlet connector 180 for the third pump 140 pointing vertically downward, allowing multiple pumps to be installed along a common drive axis while avoiding any unnecessary restriction to fluid flow on the low pressure inlet side of the pumps. For example, during the filling or intake stroke of each piston 240 in second pump 130, low pressure fluid is drawn through fluid inlet connector 160 along direct vertical flow path 162. Thus, there is no restriction to the inflow or area that may result in the creation of bubbles that may burst, thereby avoiding the creation of potential pump cavitation areas near the suction inlet of the second pump 130. Similarly, during the filling or intake stroke of each piston 240 in third pump 140, low pressure fluid is drawn through fluid inlet connector 180 along direct vertical fluid flow path 182. Thus, there is no restriction to the inflow or area that may result in the creation of bubbles that may burst, thereby avoiding the creation of potential pump cavitation areas near the suction inlet of the third pump 140.

Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the various exemplary embodiments disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims.

Claims (10)

1. A composite axial piston pump comprising a combination of a plurality of axial piston pumps connected together along a common drive axis, wherein the axial piston pumps each comprise: a pump housing having a central longitudinal axis and a housing cavity; a rotatable pump shaft extending through the pump housing along the common drive axis and into the housing chamber; a barrel fixed to the pump shaft and including a plurality of cylinders; a plurality of pistons configured for reciprocating movement within a cylinder; and a swash plate fixed to the pump housing and configured to reciprocate the pistons such that capacity chambers of the cylinders expand and contract as the pump shaft and the cylinder body rotate; a valve plate; and a port block connected to or integral with the pump housing and in fluid communication with the cylinder; the valve plate is configured to direct fluid flow from a suction port defined in the port block to the plurality of cylinders and from the cylinders to a discharge port defined in the port block; and

the plurality of axial piston pumps are connected together such that a suction port defined in a port block of at least one of the axial piston pumps is directed vertically downward and is configured to be in fluid connection with a straight suction port line oriented vertically upward from below the axial piston pump.

2. The combined axial piston pump of claim 1, wherein a first axial piston pump of the combination of the plurality of axial piston pumps includes a flange on a rear surface of the first axial piston pump having a distributed configuration of bolt holes configured to connect a second axial piston pump to the rear surface of the first axial piston pump, wherein the suction ports are defined in a port block of the second axial piston pump, oriented vertically downward and configured to fluidly connect with a straight suction port line oriented vertically upward from below the second axial piston pump.

3. The combined axial piston pump of claim 1, wherein a second axial piston pump of the combination of the plurality of axial piston pumps includes a flange on a rear surface of the second axial piston pump having a distributed configuration of bolt holes configured to connect a third axial piston pump to the rear surface of the second axial piston pump, wherein the suction ports are defined in a port block of the third axial piston pump, oriented vertically downward and configured to be in fluid connection with a straight suction port line oriented vertically upward from below the third axial piston pump.

4. The composite axial piston pump of claim 1, wherein a first axial piston pump of the combination of the plurality of axial piston pumps includes a flange on a rear surface of the first axial piston pump having a distribution of bolt holes configured to connect a second axial piston pump to the rear surface of the first axial piston pump, the suction ports defined in a port block of the second axial piston pump oriented vertically downward and configured to fluidly connect with a straight suction port line oriented vertically upward from below the second axial piston pump, and wherein the second axial piston pump of the combination of the plurality of axial piston pumps includes a flange on a rear surface of the second axial piston pump having a distribution of bolt holes configured to connect a third axial piston pump to the rear surface of the second axial pump, wherein the suction ports are defined in a port block of the third axial piston pump oriented vertically downward and configured to fluidly connect with a suction port line oriented vertically upward from below the third axial piston pump.

5. The composite axial piston pump of claim 1, wherein each of the axial piston pumps includes a respective discharge port defined in the port block of the axial piston pump, the discharge ports being oriented 180 degrees from the suction port and on opposite sides of the port block.

6. The combined axial piston pump of claim 2, wherein each of the axial piston pumps includes a respective discharge port defined in the port block of the axial piston pump, the discharge ports being oriented 180 degrees from the suction port and on opposite sides of the port block.

7. The combined axial piston pump of claim 3, wherein each of the axial piston pumps includes a respective discharge port defined in the port block of the axial piston pump, the discharge ports being oriented 180 degrees from the suction port and on opposite sides of the port block.

8. The combined axial piston pump of claim 4, wherein each of the axial piston pumps includes a respective discharge port defined in the port block of the axial piston pump, the discharge ports being oriented 180 degrees from the suction port and on opposite sides of the port block.

9. The combined axial piston pump of claim 5, wherein the respective discharge port is configured to fluidly connect with an elbow that changes a direction of fluid flow discharged from the respective discharge port.

10. A combined axial piston pump, comprising a combination of three axial piston pumps connected together along a common drive axis, wherein each of the axial piston pumps comprises: a pump housing having a central longitudinal axis and a housing cavity; a rotatable pump shaft extending through the pump housing along the common drive axis and into the housing chamber; a cylinder fixed to the pump shaft and including a plurality of cylinders; a plurality of pistons configured for reciprocating movement within a cylinder; and a swash plate fixed to the pump housing and configured to reciprocate the pistons such that capacity chambers of the cylinders expand and contract as the cylinder body rotates; a valve plate; and a port block connected to or integral with the pump housing and in fluid communication with the cylinder; the valve plate is configured to direct fluid flow from a suction port defined in the port block to the plurality of cylinders and from the cylinders to a discharge port defined in the port block; and

the three axial piston pumps are connected together such that the suction ports defined in the port blocks of at least two of the axial piston pumps are directed vertically downward and are configured to be in fluid connection with a straight suction port line oriented vertically upward from below the axial piston pumps.

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