Hydraulic pump apparatus

Abstract

A hydraulic pump apparatus (100) comprising: a housing (154); a drive shaft (132); a hydraulic fluid inlet (156) fluidly connected to one or more low-pressure manifolds (136) within the housing; first to third hydraulic fluid outlets (158A, 158B, 158C) fluidly connected to respective first to third high-pressure manifolds (138A, 138B, 138C) within the housing; and a plurality of piston cylinder units. The plurality of piston cylinder units comprises first to third cylinder groups (140A, 140B, 140C), each comprising one or more of the piston cylinder units (134). Each piston cylinder unit of the first, second and third cylinder groups comprises: a low-pressure valve (150) for controlling flow of hydraulic fluid between the one or more low-pressure manifolds (136) and the working volume; and a high-pressure valve (152) for controlling flow of hydraulic fluid from the working volume to one of the high-pressure manifolds (136).

Description

[0001] P610252PC00

[0002] Hydraulic Pump Apparatus

[0003] FIELD

[0004] The present disclosure relates to a hydraulic pump apparatus, and to a working vehicle. BACKGROUND

[0005] Working vehicles such as excavators typically have one or more hydraulic actuators such as working arm actuators, track motors, slew motors etc. Such hydraulic actuators operate by receiving a flow of hydraulic fluid from a hydraulic pump. During different operating conditions, the demand for flow rate and / or pressure of hydraulic fluid supplied to the hydraulic actuators will vary. It is therefore desirable to vary the output flow of hydraulic fluid generated by the hydraulic pump in order to meet the demanded pressure, whilst avoiding undersupplying or oversupplying hydraulic fluid and associated energy wastage. Different types of hydraulic pump apparatuses have been used for supplying a variable output of hydraulic fluid in such working vehicles. One such example is a digital displacement pump of the kind outlined in EP4257829A1.

[0006] It is an aim of the present invention to address one or more of the disadvantages associated with the prior art.

[0007] SUMMARY

[0008] The present teachings provide a hydraulic pump apparatus and a working vehicle according to the appended claims.

[0009] A first aspect of the teachings provides a hydraulic pump apparatus for a working vehicle. The hydraulic pump apparatus may comprise a drive shaft which is configured for rotation by a prime mover.

[0010] The hydraulic pump apparatus may comprise a hydraulic fluid inlet. The hydraulic fluid inlet may be fluidly connected to one or more low-pressure manifolds.

[0011] The hydraulic pump apparatus may comprise a first hydraulic fluid outlet for supplying hydraulic fluid to a first control valve group of the working vehicle. The first hydraulic fluid outlet may be fluidly connected to a first high-pressure manifold.

[0012] The hydraulic pump apparatus may comprise a second hydraulic fluid outlet for supplying hydraulic fluid to a second control valve group of the working vehicle. The second hydraulic fluid outlet may be fluidly connected to a second high-pressure manifold.P610252PC00

[0013] The hydraulic pump apparatus may comprise a third hydraulic fluid outlet for supplying hydraulic fluid to a third control valve group of the working vehicle. The third hydraulic fluid outlet may be fluidly connected to a third high-pressure manifold.

[0014] The hydraulic pump apparatus may comprise a plurality of piston cylinder units. Each of the piston cylinder units may comprise a cylinder which defines a working volume therein, and a piston which is driven by the drive shaft, and which reciprocates within the cylinder to vary the working volume. Each of the piston cylinder units may comprise a low-pressure valve for controlling flow of hydraulic fluid between the one or more low-pressure manifolds and the working volume. Each of the piston cylinder units may comprise a high-pressure valve for controlling flow of hydraulic fluid from the working volume to a high-pressure manifold (e.g., one of the first to third high-pressure manifolds).

[0015] The plurality of piston cylinder units may comprise a first cylinder group. The first cylinder group may comprise one or more of the piston cylinder units. The high-pressure valve of each piston cylinder unit of the first cylinder group may be connected (e.g., fixedly connected) to the first hydraulic fluid outlet via the first high-pressure manifold.

[0016] The plurality of piston cylinder units may comprise a second cylinder group. The second cylinder group may comprise one or more of the piston cylinder units. The high-pressure valve of each piston cylinder unit of the second cylinder group may be connected (e.g., fixedly connected) to the second hydraulic fluid outlet via the second high-pressure manifold.

[0017] The plurality of piston cylinder units may comprise a third cylinder group. The third cylinder group may comprise one or more of the piston cylinder units. The high-pressure valve of each piston cylinder unit of the third cylinder group may be connected (e.g., fixedly connected) to the third hydraulic fluid outlet via the third high-pressure manifold.

[0018] A hydraulic pump apparatus having two hydraulic fluid outlets / high-pressure manifolds may be particularly beneficial for excavators, in which efficiency savings can be gained by having separate hydraulic fluid feeds to the left / right tracks and to different actuators of the working arm (e.g., boom and dipper arm actuators). Having an additional third hydraulic fluid outlet / high-pressure manifold may facilitate further improved efficiency by offering a dedicated outlet which can be used for hydraulic actuators with different pressure / load requirements (e.g., a hydraulic slew motor of an excavator).

[0019] Having a fixed connection between each high-pressure valve and the associated hydraulic fluid outlet provides a simplified arrangement in comparison to alternative configurations. In this context, the term "fixedly connected" will be understood to mean a direct connection to the respective outlet via the respective high-pressure manifold. In other words, when "fixedly connected to the first hydraulic fluid outlet via the first high-pressureP610252PC00

[0020] manifold", outflow through the high-pressure valve(s) of the piston cylinder unit(s) of the first cylinder group always flows into the first high-pressure manifold (i.e., it does not flow into the second or third high-pressure manifolds). Similarly, when "fixedly connected to the second hydraulic fluid outlet via the second high-pressure manifold", outflow through the high-pressure valve(s) of the piston cylinder unit(s) of the second cylinder group always flows into the second high-pressure manifold (i.e., it does not flow into the first or third high-pressure manifolds). Similarly, when "fixedly connected to the third hydraulic fluid outlet via the third high-pressure manifold", outflow through the high-pressure valve(s) of the piston cylinder unit(s) of the third cylinder group always flows into the third high-pressure manifold (i.e., it does not flow into the first or second high-pressure manifolds).

[0021] The hydraulic pump apparatus may comprise a housing. The drive shaft may extend through the housing. The hydraulic fluid inlet may be provided through the housing (e.g., defining a through-path from an exterior of the housing to an interior of the housing). The one or more low-pressure manifolds may be provided within the housing. For example, the one or more low-pressure manifolds may be provided by one or more conduits (e.g., pipes) extending within an interior of the housing. As another example, the one or more low-pressure manifolds may be integrally formed within a body of the housing (e.g., as cast, machined or additively manufactured conduits within the body of the housing). The first hydraulic fluid outlet may be provided through the housing (e.g., defining a through-path from an interior of the housing to an exterior of the housing). The first high-pressure manifold may be provided within the housing. For example, the first high-pressure manifold may be provided by a conduit (e.g., pipe) extending within an interior of the housing. As another example, the first high-pressure manifold may be integrally formed within a body of the housing (e.g., as a cast, machined or additively manufactured conduit within the body of the housing).

[0022] The second hydraulic fluid outlet may be provided through the housing (e.g., defining a through-path from an interior of the housing to an exterior of the housing). The second high-pressure manifold may be provided within the housing. For example, the second high-pressure manifold may be provided by a conduit (e.g., pipe) extending within an interior of the housing. As another example, the second high-pressure manifold may be integrally formed within a body of the housing (e.g., as a cast, machined or additively manufactured conduit within the body of the housing).

[0023] The third hydraulic fluid outlet may be provided through the housing (e.g., defining a th rough -path from an interior of the housing to an exterior of the housing). The third high-pressure manifold may be provided within the housing. For example, the third high-P610252PC00

[0024] pressure manifold may be provided by a conduit (e.g., pipe) extending within an interior of the housing. As another example, the third high-pressure manifold may be integrally formed within a body of the housing (e.g., as a cast, machined or additively manufactured conduit within the body of the housing).

[0025] Each of the piston cylinder units may be provided at least partly within the housing. For example, the cylinders of the piston cylinder units may be integrally formed with a body of the housing. As another example, the piston cylinder units may be discrete from the body of the housing, but positioned at least partly (e.g., fully) within an interior of the housing.

[0026] Having a housing which encloses / contains the drive shaft, low and high-pressure manifolds and the piston cylinder units, allows the hydraulic pump apparatus to be provided as a self-contained unit. In other words, these components are all packaged together, and there is only a need to provide a mechanical connection to the drive shaft, and fluid connections to the hydraulic fluid inlet / outlets. This may facilitate simple assembly and packaging of the hydraulic pump apparatus on a working vehicle.

[0027] The hydraulic pump apparatus may comprise a controller configured to actively control the low-pressure valves and / or the high-pressure valves of the piston cylinder units to adjust the net displacement of each piston cylinder unit during each rotation of the working volume, to independently regulate the flow of fluid to the first, second and third high-pressure manifolds.

[0028] Such a controller facilitates suitable outflow of hydraulic fluid through the first to third hydraulic fluid outlets.

[0029] The hydraulic pump apparatus may comprise a controller configured to actively control the low-pressure valves and / or the high-pressure valves of the piston cylinder units to adjust the net displacement of each piston cylinder unit during each rotation of the working volume, to independently regulate the flow of fluid to the first, second and third high-pressure manifolds so that the third cylinder group supplies a lower pressure of hydraulic fluid to the third high-pressure manifold than the first and second cylinder groups supply to the respective first and second high-pressure manifolds, such that the third hydraulic fluid outlet is a dedicated low-pressure outlet for supplying hydraulic fluid to a hydraulic slew motor of the working vehicle.

[0030] Such a configuration facilitates a dedicated low-pressure outlet for a lower pressure hydraulic slew motor for an excavator. This allows the hydraulic slew motor to be actuated without parallel losses which may be associated with driving the hydraulic slew motor and a higher pressure hydraulic service from the same outlet.P610252PC00

[0031] The hydraulic pump apparatus may be configured so that the third cylinder group supplies or is able to supply a lower pressure of hydraulic fluid to the third high-pressure manifold than the first and second cylinder groups supply to the respective first and second high-pressure manifolds. It will be understood that this may be dependent on the load / operating pressure experienced by each of the three high-pressure manifolds.

[0032] Such a configuration facilitates a dedicated low-pressure outlet which may be used to supply a lower pressure hydraulic service, such as a hydraulic slew motor for an excavator. This allows the lower pressure hydraulic service to be actuated without parallel losses which may be associated with driving the lower pressure hydraulic service and a higher pressure hydraulic service from the same outlet.

[0033] The third high-pressure manifold may have an operating pressure in the range 100 bar to 300 bar.

[0034] Such an operating pressure in the third high-pressure manifold may be particularly suitable for actuating a hydraulic slew motor of an excavator.

[0035] The first and second high-pressure manifolds may have an operating pressure in the range 100 bar to around 400 bar.

[0036] Such an operating pressure in the first and second high-pressure manifolds may be particularly suitable for actuating track motors and / or working arm actuators of an excavator.

[0037] The first and second high-pressure manifolds may have an operating pressure which is greater than the operating pressure of the third high-pressure manifold by an amount in the range 50 bar to 150 bar, for example in the range 75bar to 125 bar, for example approximately 100 bar.

[0038] Optionally, wherein the first and second high-pressure manifolds have an operating pressure which is at least 50 bar greater than the operating pressure of the third high-pressure manifold; optionally at least 75 bar greater; optionally at least 100 bar greater. Such a difference in operating pressure may correspond to typical differences between the operating pressure of a hydraulic slew motor and the operating pressure of track motors / working arm actuators of an excavator.

[0039] Each of the first, second and third cylinder groups may comprise a plurality of piston cylinder units.

[0040] This facilitates a greater amount of flexibility in how much hydraulic fluid is input to the first, second and third high-pressure manifolds.P610252PC00

[0041] The third cylinder group may comprise fewer piston cylinder units than the first and / or second cylinder groups.

[0042] In this way, the third cylinder group may be configured to generate a lower flow rate at a lower pressure of the hydraulic fluid to the third high-pressure manifold, which may be beneficial for supplying a lower pressure hydraulic service (e.g., an excavator hydraulic slew motor).

[0043] The hydraulic pump apparatus may comprise 30 piston cylinder units, and wherein the third cylinder group comprises nine or ten piston cylinder units.

[0044] Such a configuration may balance the output flow rates to the first to third high-pressure manifolds, particularly when the working vehicle is an excavator, the third high-pressure manifold drives a hydraulic slew motor, and the first and second high-pressure manifolds drive other functions of the excavator.

[0045] The hydraulic pump apparatus may comprise a radial piston arrangement in which the plurality of piston cylinder units extend approximately radially and are arranged circumferentially around the drive shaft.

[0046] Such a radial piston arrangement may facilitate a compact packaging of multiple piston cylinder units that can easily be driven by a single shaft. For example, the pistons of the piston cylinder units may be sequentially driven by one or more cams coupled to the drive shaft.

[0047] The plurality of piston cylinder units may comprise a first cylinder ring of piston cylinder units positioned proximal to a first axial position along the drive shaft, and a second cylinder ring of piston cylinder units positioned proximal to a second axial position along the drive shaft, wherein the second axial position is spaced apart from the first axial position.

[0048] For a given circumferential dimension of the hydraulic pump apparatus, such a configuration of first and second spaced apart rings may facilitate a greater number of piston cylinder units, and thus a greater output of hydraulic fluid, than alternative configurations in which there is only a single ring.

[0049] The hydraulic fluid inlet, first hydraulic fluid outlet, second hydraulic fluid outlet and / or third hydraulic fluid outlet may pass through the housing between the first and second axial positions.

[0050] This may facilitate easier channelling of hydraulic fluid to and from both rings of piston cylinder units than in alternative configurations in which the hydraulic fluid inlet, first hydraulic fluid outlet, second hydraulic fluid outlet and / or third hydraulic fluid outlet pass through the housing axially outboard of the first or second axial position.P610252PC00

[0051] The piston cylinder units of the first cylinder group may be provided in the first cylinder ring, and the piston cylinder units of the second cylinder group are provided in the second cylinder ring.

[0052] This may simplify the arrangement of the first and second high-pressure manifolds, as each may only be required to channel fluid from one side of the hydraulic pump apparatus to the respective hydraulic fluid outlet.

[0053] The piston cylinder units of the third cylinder group may be provided in one of the first and second cylinder rings.

[0054] This may simplify the arrangement of the third high-pressure manifold, as it may only be required to channel fluid from one side of the hydraulic pump apparatus to the third hydraulic fluid outlet.

[0055] At least one piston cylinder unit of the third cylinder group may be provided in the first cylinder ring and wherein at least one piston cylinder unit of the third cylinder group is provided in the second cylinder ring.

[0056] In this way, the first and second cylinder groups may be more evenly sized than in alternative configurations, which may be beneficial for certain applications (e.g., those in which the first and second hydraulic fluid outlets are coupled to hydraulic actuator groups with similar pressure and flow rate requirements).

[0057] The piston cylinder units may be arranged in cylinder sets each comprising two or more piston cylinder units (e.g. three piston cylinder units), wherein the cylinder sets are arranged circumferentially around the drive shaft and spaced apart from each other such that each piston cylinder unit is closer to piston cylinder units within the same cylinder set than to piston cylinder units of adjacent cylinder sets.

[0058] Such a grouping of piston cylinder units into cylinder sets may facilitate a compact packaging of the piston cylinder units.

[0059] The cylinder sets each may comprise three piston cylinder units and wherein the hydraulic pump apparatus comprises five cylinder sets arranged circumferentially around the drive shaft; optionally, wherein the hydraulic pump apparatus comprises five cylinder sets arranged circumferentially around a first axial position along the drive shaft, and five cylinder sets arranged circumferentially around a second axial position along the drive shaft.

[0060] Such a radial piston arrangement may facilitate a compact packaging of multiple piston cylinder units that can easily be driven by a single shaft.

[0061] A second aspect of the teachings provides a working vehicle. The working vehicle may comprise a machine body, and a ground engaging propulsion structure coupled to theP610252PC00

[0062] machine body for moving the working vehicle over a ground surface. The working vehicle may comprise a working arm coupled to the machine body for performing a work function. The working vehicle may comprise a prime mover for driving movement of the groundengaging propulsion structure and / or working arm.

[0063] The working vehicle may comprise a first actuator group comprising one or more hydraulic actuators. The working vehicle may also comprise a first control valve group for directing hydraulic fluid to the first actuator group.

[0064] The working vehicle may comprise a second actuator group comprising one or more hydraulic actuators. The working vehicle may also comprise a second control valve group for directing hydraulic fluid to the second actuator group.

[0065] The working vehicle may comprise a third actuator group comprising one or more hydraulic actuators. The working vehicle may also comprise a third control valve group for directing hydraulic fluid to the third actuator group.

[0066] The working vehicle may comprise a hydraulic fluid reservoir.

[0067] The working vehicle may comprise a hydraulic pump apparatus. The hydraulic pump apparatus may comprise a drive shaft coupled to the prime mover for rotation by the prime mover.

[0068] The hydraulic pump apparatus may comprise one or more low-pressure manifolds fluidly connected to the hydraulic fluid reservoir.

[0069] The hydraulic pump apparatus may comprise a first high-pressure manifold fluidly connected (e.g., fixedly connected) to the first control valve group.

[0070] The hydraulic pump apparatus may comprise a second high-pressure manifold fluidly connected (e.g., fixedly connected) to the second control valve group.

[0071] The hydraulic pump apparatus may comprise a third high-pressure manifold fluidly connected (e.g., fixedly connected) to the third control valve group.

[0072] The hydraulic pump apparatus may comprise a plurality of piston cylinder units. Each piston cylinder unit may comprise a cylinder which defines a working volume therein, and a piston which is driven by the drive shaft, and which reciprocates within the cylinder to vary the working volume. Each piston cylinder unit may comprise a low-pressure valve for controlling flow of hydraulic fluid between the low-pressure manifold and the working volume. Each piston cylinder unit may comprise a high-pressure valve for controlling flow of hydraulic fluid from the working volume to one of the first to third high-pressure manifolds.P610252PC00

[0073] The plurality of piston cylinder units may comprise a first cylinder group comprising one or more of the piston cylinder units. The high-pressure valve of each piston cylinder unit of the first cylinder group may be connected (e.g., fixedly connected) to the first high-pressure manifold.

[0074] The plurality of piston cylinder units may comprise a second cylinder group comprising one or more of the piston cylinder units. The high-pressure valve of each piston cylinder unit of the second cylinder group may be connected (e.g., fixedly connected) to the second high-pressure manifold.

[0075] The plurality of piston cylinder units may comprise a third cylinder group comprising one or more of the piston cylinder units. The high-pressure valve of each piston cylinder unit of the third cylinder group may be connected (e.g., fixedly connected) to the third high-pressure manifold.

[0076] A hydraulic pump apparatus having two high-pressure manifolds may be particularly beneficial for excavators, in which efficiency savings can be gained by having separate hydraulic fluid feeds to the left / right tracks and to different actuators of the working arm (e.g., boom and dipper arm actuators). Having an additional third high-pressure manifold may facilitate further improved efficiency by offering a dedicated outlet which can be used for hydraulic actuators with different pressure / load requirements (e.g., a hydraulic slew motor of an excavator).

[0077] Having a fixed connection between each high-pressure valve and the associated high-pressure manifold provides a simplified arrangement in comparison to alternative configurations. In this context, the term "fixedly connected" will be understood to mean a direct connection to the respective control valve group via the respective high-pressure manifold. In other words, when "fixedly connected to the first high-pressure manifold", outflow through the high-pressure valve(s) of the piston cylinder unit(s) of the first cylinder group always flows into the first high-pressure manifold (i.e., it does not flow into the second or third high-pressure manifolds). Similarly, when "fixedly connected to the second high-pressure manifold", outflow through the high-pressure valve(s) of the piston cylinder unit(s) of the second cylinder group always flows into the second high-pressure manifold (i.e., it does not flow into the first or third high-pressure manifolds). Similarly, when "fixedly connected to the third high-pressure manifold", outflow through the high-pressure valve(s) of the piston cylinder unit(s) of the third cylinder group always flows into the third high-pressure manifold (i.e., it does not flow into the first or second high-pressure manifolds).

[0078] The first to third high-pressure manifolds of the hydraulic pump apparatus may be independently connected to the respective first to third control valve groups so that eachP610252PC00

[0079] high-pressure manifold only supplies hydraulic fluid to a single one of the first to third control valve groups.

[0080] This provides a simple configuration in which no switching valves need to be actuated in order to direct hydraulic fluid from the high-pressure manifolds to the respective control valve groups.

[0081] In other configurations, the first and second control valve groups may comprise one or more merging valves for combining flow from the first and second high-pressure manifolds.

[0082] Optionally, the working vehicle comprises a controller configured to actively control the low-pressure valves and / or high-pressure valves of the piston cylinder units to adjust the net displacement of each piston cylinder unit during each rotation of the working volume to independently regulate the flow of fluid to the first, second and third high-pressure manifolds.

[0083] Such a controller facilitates suitable supply of hydraulic fluid to the first to third actuator groups.

[0084] The machine body may comprise an undercarriage supported on the ground-engaging propulsion structure and a superstructure which is configured to rotate relative to the undercarriage about a vertical axis, wherein the first and second actuator groups comprise hydraulic actuators associated with the ground-engaging propulsion structure and / or actuation of the working arm, and wherein the third actuator group comprises a hydraulic slew actuator configured to rotate the superstructure relative to the undercarriage.

[0085] A hydraulic slew actuator (e.g. slew motor) typically operates at a different pressure than actuators associated with propulsion (e.g. track motors) or actuation of the working arm (e.g. working arm cylinders). Therefore, by having the third high-pressure manifold supply the hydraulic slew actuator, this facilitates optimising of pressure in the different high-pressure manifolds and thus reducing inefficiencies associated with parallel losses.

[0086] The third actuator group may comprise only the hydraulic slew actuator, such that the third high-pressure manifold is a dedicated hydraulic fluid supply for the hydraulic slew actuator.

[0087] The working vehicle may be configured so that the third cylinder group supplies or is able to supply a lower pressure of hydraulic fluid to the third high-pressure manifold than the first and second cylinder groups supply to the respective first and second high-pressure manifolds. It will be understood that this may be dependent on the load / operating pressure experienced by each of the three high-pressure manifolds.P610252PC00

[0088] Optionally, the third high-pressure manifold has an operating pressure in a range of 100 to 300 bar.

[0089] Optionally, the first and second high-pressure manifolds have an operating pressure in a range of 100 to 400 bar.

[0090] Optionally, the first and second high-pressure manifolds may have an operating pressure which is at least 50 bar greater than the operating pressure of the third high-pressure manifold, optionally at least 75 bar greater, optionally at least 100 bar greater.

[0091] The first actuator group may comprise: a first track motor for driving a first track of the ground-engaging propulsion structure; and / or a boom actuator for raising or lowering a boom of the working arm; and / or an implement actuator for actuating an implement of the working arm.

[0092] The second actuator group may comprise: a second track motor for driving a second track of the ground-engaging propulsion structure; and / or a dipper arm actuator for pivoting a dipper arm of the working arm relative to the boom of the working vehicle; and / or an auxiliary actuator port for connecting one or more auxiliary actuators to the second high-pressure manifold.

[0093] The hydraulic pump apparatus may be a hydraulic pump apparatus according to the first aspect.

[0094] Such a working vehicle benefits from the advantages of the hydraulic pump apparatus of the first aspect, outlined above.

[0095] BRIEF DESCRIPTION OF DRAWINGS

[0096] Embodiments will now be described by way of example only with reference to the accompanying figures, in which:

[0097] Figure 1 is a side view of a working vehicle, according to an embodiment;

[0098] Figure 2 is a schematic diagram of a hydraulic system of the working vehicle of Figure 1;

[0099] Figure 3 is a schematic view of a hydraulic pump apparatus for the hydraulic system of Figure 2, in cross section along a drive shaft of the hydraulic pump apparatus;

[0100] Figure 4 is schematic view of a hydraulic pump apparatus for the hydraulic system of Figure 2, in cross section across the drive shaft of the hydraulic pump apparatus;

[0101] Figure 5 is a plan view of a cylinder set of the hydraulic pump apparatus of Figure 4;

[0102] Figure 6 is a schematic diagram of the hydraulic pump apparatus of Figures 4 and 5;

[0103] Figure 7 shows a first grouping of piston cylinder units of the hydraulic pumpP610252PC00

[0104] apparatus of Figure 6; and

[0105] Figure 8 shows a second grouping of piston cylinder units of the hydraulic pump apparatus of Figure 6.

[0106] DETAILED DESCRIPTION

[0107] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of various embodiments and the teachings. However, those skilled in the art will understand that: the present teachings may be practiced without these specific details or with known equivalents of these specific details; that the present teachings are not limited to the described embodiments; and, that the present teachings may be practiced in a variety of alternative embodiments. It will also be appreciated that well known methods, procedures, components, and systems may not have been described in detail.

[0108] With reference to Figure 1, a working vehicle is indicated at 10. The illustrated working vehicle 10 is of the kind known as an excavator. In particular, the illustrated working vehicle 10 is a tracked excavator. In other embodiments, the working vehicle 10 may be another type of working vehicle (e.g., a wheeled excavator, or another type of working vehicle).

[0109] The illustrated working vehicle 10 has a machine body 12 and a ground-engaging propulsion structure 14 which is coupled to the machine body 12 for moving the working vehicle 10 over a ground surface.

[0110] In the illustrated embodiment, the ground-engaging propulsion structure 14 is provided by first and second tracks 16. Other types of propulsion structure (e.g., wheels) may be provided in other embodiments.

[0111] In the illustrated embodiment, the machine body 12 includes an undercarriage 17 which is supported on the ground-engaging propulsion structure 14, and a superstructure 18 provided above the undercarriage 17. The illustrated superstructure 18 is configured to rotate relative to the undercarriage 17 about a vertical axis. In particular, a slew actuator 104 (e.g., a hydraulic slew motor) is provided for slewing the superstructure 18 relative to the undercarriage 17. The slew actuator 104 is part of a hydraulic system 100 of the working vehicle (described in more detail below).

[0112] In the illustrated embodiment, the superstructure 18 has an operator cab 20 in which an operator can sit to control the working vehicle 10 (e.g., via user controls 22).

[0113] The working vehicle 10 has a prime mover 30 (illustrated schematically on Figure 1). In particular, the prime mover 30 is an internal combustion engine. In the illustratedP610252PC00

[0114] embodiment, the internal combustion engine 30 is shown as part of the superstructure 18. In alternative embodiments, the internal combustion engine 30 is part of the undercarriage 17. The internal combustion engine 30 provides an energy source for driving the groundengaging propulsion structure 14 and / or for movement of a working arm 24 (described below). In addition, the prime mover 30 provides an energy source for driving hydraulic actuators of a hydraulic system 100 of the working vehicle 10 (described below with reference to Figure 2).

[0115] In some embodiments, the prime mover 30 may include a different energy source instead of or in addition to the internal combustion engine (e.g., a battery and an electric motor driven by the battery).

[0116] In the illustrated embodiment, first and second track motors 102A, 102B are provided for propelling the working vehicle 10. In other words, the first and second track motors 102A, 102B are provided for actuating a propulsion function of the working vehicle 10. The first and second track motors 102A, 102B are hydraulic motors which are part of the hydraulic system 100 of the working vehicle 10. The first track motor 102A is configured to drive the first track 16 (e.g., a left track) of the ground-engaging propulsion structure 14, and the second track motor 102B is configured to drive the second track 16 (e.g., a right track) of the ground-engaging propulsion structure 14.

[0117] The illustrated working vehicle 10 includes a working arm 24 which is coupled to the machine body 12 (in particular, to the superstructure 18). The working arm 24 can be actuated by one or more working arm actuators 106, 108, 110 of the hydraulic system 100 to perform a work function or working arm operation (e.g., an excavating operation). In other words, the working arm actuators 106, 108, 110 are associated with movement of the working arm 24.

[0118] In the illustrated embodiment, the working arm 24 has a boom 24A and a dipper arm 24B. The boom 24A is pivotally connected to the machine body 12 (e.g., to the superstructure 18). The dipper arm 24B is pivotally connected to the boom 24A (i.e., at the distal end of the boom 24A). In the illustrated embodiment, an implement 24C (e.g., an excavating bucket) is pivotally connected to the dipper arm 24B.

[0119] The working arm actuators include a boom actuator 106, a dipper arm actuator 108, and an implement actuator 110. The illustrated working arm actuators are hydraulic cylinders. The boom actuator 106 is configured to pivot the boom 24A relative to the machine body 12. For example, in the illustrated configuration the boom actuator 106 is arranged so that extension of the boom actuator 106 raises the boom 24A, and so that retraction of the boom actuator 106 lowers the boom 24A.P610252PC00

[0120] The dipper arm actuator 108 is configured to pivot the dipper arm 24B relative to the boom 24A. For example, in the illustrated configuration the dipper arm actuator 108 is arranged so that extension of the dipper arm actuator 108 pivots the dipper arm 24B to decrease an angle between the boom 24A and the dipper arm 24B, and so that retraction of the dipper arm actuator 108 pivots the dipper arm 24B to increase the angle between the boom 24A and the dipper arm 24B.

[0121] The implement actuator 110 is configured to pivot the implement 24C relative to the dipper arm 24B. For example, in the illustrated embodiment where the implement 24C is a bucket, the implement actuator 110 is arranged so that extension of the implement actuator 110 corresponds to closing the bucket 24C, and so that retraction of the implement actuator 110 corresponds to opening the bucket 24C.

[0122] Referring now to Figure 2, the hydraulic system 100 of the working vehicle 10 is illustrated. The hydraulic system 100 incudes a first actuator group 101A which includes one or more hydraulic actuators. In particular, the first actuator group 101A includes the first track motor 102A, the boom actuator 106, and the implement actuator 110.

[0123] The hydraulic system 100 also includes a second actuator group 101B which includes one or more hydraulic actuators. In particular, the second actuator group 101B includes the second track motor 102B, the dipper arm actuator 108, and an auxiliary actuator 112 for actuating an auxiliary function of the working vehicle 10.

[0124] The hydraulic system 100 also includes a third actuator group 101C which includes the slew actuator 104.

[0125] A first control valve group 120A is provided for directing hydraulic fluid to the first actuator group 101A. Similarly, a second control valve group 120B is provided for directing hydraulic fluid to the second actuator group 101B. Similarly, a third control valve group 120C is provided for directing hydraulic fluid to the third actuator group 101C.

[0126] Each of the control valve groups 120A, 120B, 120C includes one or more valves which allow a direction of actuation of the respective hydraulic actuators 102A, 102B, 104, 106, 108, 110, 112 to be controlled (e.g., extension / retraction of a hydraulic cylinder, or first and second rotational direction of a hydraulic motor). For example, each control valve group 120A, 120B, 120C may include a directional control valve for each associated hydraulic actuator (e.g., the first and second control valve groups 120A, 120B may have three directional control valves, and the third control valve group 120C may have a single directional control valve).

[0127] The hydraulic system 100 also includes a hydraulic fluid reservoir 114 and a hydraulic pump apparatus 130 for supplying hydraulic fluid from the hydraulic fluid reservoir 114 toP610252PC00

[0128] the control valve groups 120A, 120B, 120C along respective first to third hydraulic feed lines 122A, 122B, 122C. In this way, when one of the hydraulic actuators 102A, 102B, 104, 106, 108, 110, 112 is actuated, hydraulic fluid can be channelled from the hydraulic fluid reservoir 114 via the hydraulic pump apparatus 130 along the hydraulic feed lines 122A, 122B, 122C, through the respective control valve group 120A, 120B, 120C to the hydraulic actuator.

[0129] It will be understood that, although not illustrated, each of the control valve groups 120A, 120B, 120C is also connected to the hydraulic fluid reservoir 114 via one or more hydraulic return lines. In this way, when one of the hydraulic actuators 102A, 102B, 104, 106, 108, 110, 112 is actuated, hydraulic fluid which is expelled from the hydraulic actuator can be channelled through the respective control valve group 120A, 120B, 120C, along the hydraulic return line to the hydraulic fluid reservoir 114.

[0130] The hydraulic pump apparatus 130 will now be described in more detail. The hydraulic pump apparatus 130 has a drive shaft 132 coupled to the prime mover 30 for rotation by the prime mover 30. The drive shaft 132 is configured to drive a plurality of piston cylinder units 134, as will be described in more detail below.

[0131] The hydraulic pump apparatus 130 has one or more low-pressure manifolds 136 which are fluidly connected to the hydraulic fluid reservoir 114. The hydraulic pump apparatus 130 also has a first high-pressure manifold 138A which is fixedly connected to the first control valve group 120A (e.g., via the first hydraulic feed line 122A). The hydraulic pump apparatus 130 also has a second high-pressure manifold 138B which is fixedly connected to the second control valve group 120B (e.g., via the second hydraulic feed line 122B). The hydraulic pump apparatus 130 also has a third high-pressure manifold 138C which is fluidly connected to the third control valve group 120C (e.g., via the third hydraulic feed line 122C).

[0132] As will be described in more detail below, the plurality of piston cylinder units 134 are split into first, second and third cylinder groups 140A, 140B, 140C (illustrated schematically in Figure 2).

[0133] The first cylinder group 140A includes one or more piston cylinder units 134 which feed the first high-pressure manifold 138A. Similarly, the second cylinder group 140B includes one or more piston cylinder units 134 which feed the second high-pressure manifold 138B. Similarly, the third cylinder group 140C includes one or more piston cylinder units 134 which feed the third high-pressure manifold 138C.

[0134] The structure of the piston cylinder units 134 is illustrated schematically in Figure 3. In particular, each piston cylinder unit 134 has a cylinder 142 which defines a working volume 144 therein. Each piston cylinder unit 134 also has a piston 146 which is driven by theP610252PC00

[0135] drive shaft 132 and which reciprocates within the cylinder 142 to vary the working volume 144. For example, Figure 3 illustrates piston cylinder units 134 on an upper side of the drive shaft 132 in which the piston 146 is positioned radially inward so that the working volume 144 is maximised, and piston cylinder units 134 on a lower side of the drive shaft 132 in which the piston 146 is positioned radially outward so that the working volume 144 is minimised. The pistons 146 are moveable by a cam 148 coupled to the drive shaft 132 to facilitate the reciprocating motion between the two piston positions illustrated in Figure 3.

[0136] Each piston cylinder unit 134 also has a low-pressure valve 150 for controlling flow of hydraulic fluid between the low-pressure manifold 136 and the working volume 144, and a high-pressure valve 152 for controlling flow of hydraulic fluid from the working volume 144 to one of the first to third high-pressure manifolds 138A, 138B, 138C.

[0137] In the configuration of Figure 2, the high-pressure valve 152 of each piston cylinder unit 134 of the first cylinder group 140A is fixedly connected to the first high-pressure manifold 138A. Similarly, the high-pressure valve 152 of each piston cylinder unit 134 of the second cylinder group 140B is fixedly connected to the second high-pressure manifold 138B. Similarly, the high-pressure valve 152 of each piston cylinder unit 134 of the third cylinder group 140C is fixedly connected to the third high-pressure manifold 138C.

[0138] In the illustrated configuration, the first to third high-pressure manifolds 138A, 138B, 138C of the hydraulic pump apparatus 130 are independently connected to the respective first to third control valve groups 120A, 120B, 120C. In this way, each high-pressure manifold 138A, 138B, 138C only supplies hydraulic fluid to a single one of the first to third control valve groups 120A, 120B, 120C.

[0139] It will be understood that, because the third actuator group 101C only has a single hydraulic actuator, i.e., the hydraulic slew actuator 104, the third high-pressure manifold 138C is a dedicated hydraulic fluid supply for the hydraulic slew actuator 104. The hydraulic slew actuator 104 typically operates at a different pressure to actuators associated with propulsion (e.g., track motors 102A, 102B) or actuation of the working arm (e.g., working arm cylinders 106, 108, 110). Therefore, by having the third high-pressure manifold 138C supply the hydraulic slew actuator 104 separately, this facilitates optimising of the flow rate and pressure in the different high-pressure manifolds 138A, 138B, 138C and thus reduces inefficiencies associated with parallel losses.

[0140] In some configurations, the working vehicle 10 is configured so that the third cylinder group 140C generates a flow rate to supply a lower pressure of hydraulic fluid to the third high-pressure manifold 138C than the flow rate generated by the first and second cylinder groups 140A, 140B supplies to the respective first and second high-pressure manifoldsP610252PC00

[0141] 138A, 138B. For example, the third high-pressure manifold 138C may have an operating pressure in the range 100 to 300 bar, whereas the first and second high-pressure manifolds may have an operating pressure in the range 100 to 400 bar. In other configurations, different ranges of operator pressure may be used, but the first and second high-pressure manifolds 138A, 138B may still have an operating pressure which is greater than the operating pressure of the third high-pressure manifold 138C (e.g., at least 50 bar greater, e.g., at least 75 bar greater, e.g., at least 100 bar greater). The first and second high-pressure manifolds 138A, 138B have an operating pressure which is greater than the operating pressure of the third high-pressure manifold 138C by an amount in the range 50 bar to 150 bar, for example in the range 75bar to 125 bar, for example approximately 100 bar.

[0142] In some configurations, the first and second control valve groups 120A, 120B may have one or more merging valves for combining flow from the first and second high-pressure manifolds 138A, 138B.

[0143] The working vehicle 10 has a controller 50 configured to actively control the low-pressure valves 150 and / or high-pressure valves 152 of the piston cylinder units 134 to adjust the net displacement of each piston cylinder unit 134 during each rotation of the working volume 144 to independently regulate the flow of fluid to the first, second and third high-pressure manifolds 138A, 138B, 138C. In this way, the controller 50 ensures that a flow rate generated by the first, second and third piston cylinder groups 140A, 140B, 140C produces the desired pressure of hydraulic fluid to be supplied to the control valve groups 120A, 120B, 120C.

[0144] It will be understood that, because the third high-pressure manifold 138C is a dedicated hydraulic fluid supply for the hydraulic slew actuator 104 (as mentioned above), the controller 50 is configured to independently regulate the flow of fluid to the first, second and third high-pressure manifolds 138A, 138B, 138C so that the third cylinder group 140C supplies a lower pressure of hydraulic fluid to the third high-pressure manifold 138C than the first and second cylinder groups 140A, 140B supply to the respective first and second high-pressure manifolds 138A, 138B.

[0145] The controller 50 may comprise: control circuitry; and / or processor circuitry; and / or at least one application specific integrated circuit (ASIC); and / or at least one field programmable gate array (FPGA); and / or single or multi-processor architectures; and / or sequential / parallel architectures; and / or at least one programmable logic controllers (PLCs); and / or at least one microprocessor; and / or at least one microcontroller; and / or a central processing unit (CPU), to perform the described methods. The controller 50 may include an associated memory or the memory may be located locally to the controller or remotely. The memory may be a non-volatile flash memory.P610252PC00

[0146] The way in which the controller 50 regulates flow rate and in which the low-pressure valves 150 and high-pressure valves 152 operate may be accomplished via any suitable means (e.g., following control strategies outlined in EP4257829A1).

[0147] For example, each of the low-pressure valves 150 may be an electronically actuated valve (e.g., in the form of an electronically actuated face-sealing poppet valve). Each low-pressure valve 150 may be operable to selectively seal off a channel extending from the working volume 144 to the low-pressure manifold 136. Each low-pressure valve 150 may be normally open solenoid actuated valve which opens passively when the pressure within the working volume 144 is less than or equal to the pressure within the low-pressure manifold 136, i.e. during an intake stroke of the piston 146, to bring the working volume 144 into fluid communication with the low-pressure manifold 136. Each low-pressure valve 150 may be selectively closable under the active control of the controller 50 (via a control line 52) to bring the working volume 144 out of fluid communication with the low-pressure manifold 136. Each low-pressure valve 150 may alternatively be a normally closed valve. As another example, each of the high-pressure valves 152 may be in the form of a pressure actuated delivery valve. Each high-pressure valve 152 may be operable to seal off a respective channel extending from the working volume 144 to the respective high-pressure manifold 138A, 138B, 138C. Each high-pressure valve 152 may function as a normally closed pressure-opening check valve, which opens passively due to the pressure difference across the valve, and taking into account the force of a biasing member within the high-pressure valve 152. Each high-pressure valve 152 also functions as a normally closed solenoid actuated check valve which the controller 50 may selectively hold open (via a control line 54) once that high-pressure valve 152 is opened by pressure within the working volume 144. Typically, the high-pressure valves 152 are not openable by the controller 50 against pressure in the respective high-pressure manifold 138A, 138B, 138C. Each high-pressure valve 152 may additionally be openable under the control of the controller 50 when there is pressure in the respective high-pressure manifold 138A, 138B, 138C but not in the working volume 144, or may be partially openable.

[0148] Referring now to Figures 3 to 8, the structure of the hydraulic pump apparatus 130 is outlined in more detail.

[0149] The hydraulic pump apparatus 130 has a housing 154, and the drive shaft 132 extends through the housing 154 (e.g., from a left side of the housing 154 towards a right side of the housing 154 as illustrated in Figure 3).

[0150] The hydraulic pump apparatus 130 also includes a hydraulic fluid inlet 156 provided through the housing 154 (e.g., defining a through-path from an exterior 154a of the housing 154 to an interior 154b of the housing 154). The hydraulic fluid inlet 156 is fluidlyP610252PC00

[0151] connected to the one or more low-pressure manifolds 136, which are provided within the housing 154. Although the one or more low-pressure manifolds 136 are illustrated schematically in Figure 3, they may be provided within the housing 154 in any suitable manner. For example, the one or more low-pressure manifolds 136 may be provided by one or more conduits (e.g., pipes) extending within the interior 154b of the housing 154. As another example, the one or more low-pressure manifolds 136 may be integrally formed within a body of the housing 154 (e.g., as cast, machined or additively manufactured conduits within the body of the housing 154).

[0152] The hydraulic pump apparatus 130 also includes a first hydraulic fluid outlet 158A provided through the housing 154 (e.g., defining a through-path from the interior 154b of the housing 154 to the exterior 154a of the housing 154). The first hydraulic fluid outlet 158A is connected to the first high-pressure manifold 138A so that hydraulic fluid can be supplied from the first high-pressure manifold 138A (which is provided within the housing 154) to the first hydraulic feed line 122A and the associated first control valve group 120A. For example, the first high-pressure manifold 138A may be provided by a conduit (e.g., pipe) extending within the interior 154b of the housing 154. As another example, the first high-pressure manifold 138A may be integrally formed within a body of the housing 154 (e.g., as a cast, machined or additively manufactured conduit within the body of the housing 154).

[0153] It will be understood that the high-pressure valve 152 of each piston cylinder unit 134 of the first cylinder group 140A is fixedly connected to the first hydraulic fluid outlet 158A via the first high-pressure manifold 138A.

[0154] The hydraulic pump apparatus 130 also includes a second hydraulic fluid outlet 158B provided through the housing 154 (e.g., defining a through-path from the interior 154b of the housing 154 to the exterior 154a of the housing 154). The second hydraulic fluid outlet 158B is connected to the second high-pressure manifold 138B so that hydraulic fluid can be supplied from the second high-pressure manifold 138B (which is provided within the housing 154) to the second hydraulic feed line 122B and the associated second control valve group 120B. For example, the second high-pressure manifold 138B may be provided by a conduit (e.g., pipe) extending within the interior 154 of the housing 154. As another example, the second high-pressure manifold 138B may be integrally formed within a body of the housing 154 (e.g., as a cast, machined or additively manufactured conduit within the body of the housing 154).

[0155] It will be understood that the high-pressure valve 152 of each piston cylinder unit 134 of the second cylinder group 140B is fixedly connected to the second hydraulic fluid outlet 158B via the second high-pressure manifold 138B.P610252PC00

[0156] The hydraulic pump apparatus 130 also includes a third hydraulic fluid outlet 158C provided through the housing 154 (e.g., defining a through-path from the interior 154b of the housing 154 to the exterior 154a of the housing 154). The third hydraulic fluid outlet 158C is connected to the third high-pressure manifold 138C so that hydraulic fluid can be supplied from the third high-pressure manifold 138C (which is provided within the housing 154) to the third hydraulic feed line 122C and the associated third control valve group 120C. For example, the third high-pressure manifold 138C may be provided by a conduit (e.g., pipe) extending within the interior 154b of the housing 154. As another example, the third high-pressure manifold 138C may be integrally formed within a body of the housing 154 (e.g., as a cast, machined or additively manufactured conduit within the body of the housing 154).

[0157] It will be understood that the high-pressure valve 152 of each piston cylinder unit 134 of the third cylinder group 140C is fixedly connected to the third hydraulic fluid outlet 158C via the third high-pressure manifold 138C.

[0158] Each of the piston cylinder units 134 is provided within the housing 154. In some configurations, the cylinders 142 of the piston cylinder units 134 may be integrally formed with a body of the housing 154. In other configurations, the piston cylinder units 134 may be discrete from the body of the housing 154, but positioned at least partly (e.g., fully) within the interior 154b of the housing 154.

[0159] Figure 6 illustrates a plurality of piston cylinder units 134 which may be grouped in different ways to provide the first, second and third cylinder groups 140A, 140B, 140C of the hydraulic pump apparatus 100. In the illustrated configuration, there are 30 piston cylinder units 134, but other numbers of piston cylinder units 134 may be used in different configurations.

[0160] In some configurations, each of the first, second and third cylinder groups 140A, 140B, 140C has a plurality of piston cylinder units 134. For example, Figure 7 illustrates a configuration in which the first cylinder group 140A has 15 of the piston cylinder units 134, the second cylinder group 140B has six of the piston cylinder units 134, and the third cylinder group 140C has nine of the piston cylinder units 134. It will be understood that the third cylinder group 140C has nine of the piston cylinder units 134 may have nine or ten of the piston cylinder units. However, in other embodiments, the first, second and third cylinder groups 140A, 140B, 140C may have different numbers of piston cylinder units therein.

[0161] For example, Figure 8 illustrates a configuration in which the first cylinder group 140A contains twelve of the piston cylinder units 134, the second piston cylinder group 140B contains nine of the piston cylinder units 134, and the third cylinder group 140C has nineP610252PC00

[0162] of the piston cylinder units 134. Again, in this example, it will be understood that the third cylinder group 140C may have nine of ten of the piston cylinder units 134.

[0163] Alternative groupings of the piston cylinder units 134 may be used in other configurations. In some embodiments, the third cylinder group 140C may have fewer piston cylinder units 134 than the first and / or second cylinder groups 140A, 140B. The third cylinder group 140C may have, for example, fewer piston cylinder units 134 than the total number of piston cylinder units in the first and second cylinder groups 140A, 140B.

[0164] In some configurations, the hydraulic pump apparatus 100 has a radial piston arrangement in which the plurality of piston cylinder units 134 each extend approximately radially and are arranged circumferentially around the drive shaft 132. For example, such a configuration is illustrated in Figures 3 and 4. Such a radial piston arrangement may facilitate a compact packaging of multiple piston cylinder units 134 that can easily be driven by a single drive shaft 132. For example, the pistons 146 of the piston cylinder units 134 may be sequentially driven by one or more cams 148 coupled to the drive shaft 132.

[0165] In Figure 3, the plurality of piston cylinder units 134 are arranged in a first cylinder ring 160A of piston cylinder units 134 positioned proximal to a first axial position 162A along the drive shaft 132, and a second cylinder ring 160B of piston cylinder units 134 positioned proximal to a second axial position 162B along the drive shaft 132. The second axial position 162B is spaced apart from the first axial position 162A. For a given circumferential dimension of the hydraulic pump apparatus 100, such a configuration of first and second spaced apart rings 160A, 160B may facilitate a greater number of piston cylinder units 134, and thus a greater output of hydraulic fluid, than alternative configurations in which there is only a single ring. In the cross-sectional view of Figure 4, only the first cylinder ring 160A is illustrated.

[0166] The first and second cylinder rings 160A, 160B are illustrated schematically in Figures 6 to 8, with the first cylinder ring 160A being represented by the lower row of piston cylinder units 134 and the second cylinder ring 160B being represented by the upper row of piston cylinder units 134.

[0167] In the configuration of Figure 3, the hydraulic fluid inlet 156, first hydraulic fluid outlet 158A, second hydraulic fluid outlet 158B and third hydraulic fluid outlet 158C pass through the housing 154 between the first and second axial positions 162A, 162B. This may facilitate easier channelling of hydraulic fluid to and from both rings 160A, 160B of piston cylinder units 134 than in alternative configurations in which the hydraulic fluid inlet 156, first hydraulic fluid outlet 158A, second hydraulic fluid outlet 158B and / or third hydraulicP610252PC00

[0168] fluid outlet 158C pass through the housing 154 axially outboard of the first or second axial position 162A, 162B.

[0169] In the configurations of Figures 7 and 8, the piston cylinder units 134 of the first cylinder group 140A are provided in the first cylinder ring 160A, and the piston cylinder units of the second cylinder group 140B are provided in the second cylinder ring 160B. This may simplify the arrangement of the first and second high-pressure manifolds 138A, 138B, as each may only be required to channel fluid from one side of the hydraulic pump apparatus 100 to the respective hydraulic fluid outlet 158A, 158B.

[0170] In the configuration of Figure 7, the piston cylinder units 134 of the third cylinder group 140C are provided in one of the first and second cylinder rings 160A, 160B. This may simplify the arrangement of the third high-pressure manifold 138C, as it may only be required to channel fluid from one side of the hydraulic pump apparatus 100 to the third hydraulic fluid outlet 158C. In particular, the piston cylinder units 134 of the third cylinder group 140C are provided in the second cylinder ring 160B.

[0171] In the configuration of Figure 8, at least one piston cylinder unit 134 of the third cylinder group 140C is provided in the first cylinder ring 160A and at least one piston cylinder unit 134 of the third cylinder group 140C is provided in the second cylinder ring 160B. In particular, the piston cylinder units 134 of the third cylinder group 140C are evenly divided between the first and second cylinder rings 160A, 160B (e.g., with 3 piston cylinder units 134 in each cylinder ring 160A, 160B). In this way, the first and second cylinder groups 140A, 140B may be more evenly sized than in alternative configurations, which may be beneficial for certain applications (e.g., those in which the first and second hydraulic fluid outlets 158A, 158B are coupled to hydraulic actuator groups with similar hydraulic pressure requirements).

[0172] As best illustrated in Figures 4 and 5, the piston cylinder units 134 may be arranged in cylinder sets 164 each having two or more piston cylinder units 134 (e.g., three piston cylinder units 134). The cylinder sets 164 are arranged circumferentially around the drive shaft 132 and spaced apart from each other such that each piston cylinder unit 134 is closer to piston cylinder units 134 within the same cylinder set 164 than to piston cylinder units 134 of adjacent cylinder sets 164. Such a grouping of piston cylinder units 134 into cylinder sets 164 may facilitate a compact packaging of the piston cylinder units 134. The cylinder sets 164 may each have three piston cylinder units 134. Such an arrangement is illustrated in the plan view of Figure 5. It will be understood that the cylinder sets 164 of Figure 4 may have the same configuration, but that only two of the three piston cylinder units 134 of each cylinder set 164 are visible in this cross-sectional view.P610252PC00

[0173] In the configuration of Figure 4, the hydraulic pump apparatus 100 has five cylinder sets 164 arranged circumferentially around the drive shaft 132. The illustrated five cylinder sets 164 define the first cylinder ring 160A (e.g., the illustrated cylinder sets 164 are arranged around the first axial position 162A). The hydraulic pump apparatus 100 may also include a similar configuration defining the second cylinder ring 160B (e.g., five cylinder sets 164 arranged circumferentially around the drive shaft 132 at the second axial position 162B).

[0174] The cylinder sets 164 are illustrated schematically as groups of three piston cylinder units 134 in Figures 6 to 8. It will be understood that each cylinder set 164 may have a common connection to the respective low-pressure manifold 136 and high-pressure manifold 138A, 138B, 138C.

[0175] In the configuration illustrated in Figure 5, each cylinder set 164 has an approximately triangular shape when viewed in plan view (i.e., corresponding to a radially inward view). In particular, the housing 154 has a protrusion 166 of approximately triangular crosssection, which encloses the piston cylinder units 134 of the cylinder set 164. The piston cylinder units 134 are positioned within the housing protrusion 166 in a triangular formation (e.g., approximately equidistant from each other).

[0176] It will be understood that the particular configurations of piston cylinder units 134 illustrated in Figures 3 to 8 is just for example. Various alternative configurations may be used.

[0177] The one or more embodiments are described above by way of example only and it will be appreciated that the variations are possible without departing from the scope of protection afforded by the appended claims. It should also be noted that whilst the appended claims set out particular combinations of features described above, the scope of the present disclosure is not limited to the particular combinations hereafter claimed, but instead extends to encompass any combination of features herein disclosed.

Claims

P610252PC00Claims1. A hydraulic pump apparatus for a working vehicle, the hydraulic pump apparatus comprising:a housing;a drive shaft extending through the housing and being configured for rotation by a prime mover;a hydraulic fluid inlet provided through the housing, the hydraulic fluid inlet being fluidly connected to one or more low-pressure manifolds within the housing;a first hydraulic fluid outlet provided through the housing for supplying hydraulic fluid to a first control valve group of the working vehicle, the first hydraulic fluid outlet being fluidly connected to a first high-pressure manifold within the housing;a second hydraulic fluid outlet provided through the housing for supplying hydraulic fluid to a second control valve group of the working vehicle, the second hydraulic fluid outlet being fluidly connected to a second high-pressure manifold within the housing; a third hydraulic fluid outlet provided through the housing for supplying hydraulic fluid to a third control valve group of the working vehicle, the third hydraulic fluid outlet being fluidly connected to a third high-pressure manifold within the housing;a plurality of piston cylinder units provided at least partly within the housing, wherein each of the piston cylinder units comprises: a cylinder which defines a working volume therein; a piston which is driven by the drive shaft and which reciprocates within the cylinder to vary the working volume; a low-pressure valve for controlling flow of hydraulic fluid between the one or more low-pressure manifolds and the working volume; and a high-pressure valve for controlling flow of hydraulic fluid from the working volume to one of the first to third high-pressure manifolds;wherein the plurality of piston cylinder units comprises:a first cylinder group comprising one or more of the piston cylinder units, wherein the high-pressure valve of each piston cylinder unit of the first cylinder group is fixedly connected to the first hydraulic fluid outlet via the first high- pressure manifold;a second cylinder group comprising one or more of the piston cylinder units, wherein the high-pressure valve of each piston cylinder unit of the second cylinder group is fixedly connected to the second hydraulic fluid outlet via the second high- pressure manifold; anda third cylinder group comprising one or more of the piston cylinder units, wherein the high-pressure valve of each piston cylinder unit of the third cylinder group is fixedly connected to the third hydraulic fluid outlet via the third high- pressure manifold.24P610252PC002. The hydraulic pump apparatus of claim 1, wherein the hydraulic pump apparatus comprises a controller configured to actively control the low-pressure valves and / or the high-pressure valves of the piston cylinder units to adjust the net displacement of each piston cylinder unit during each rotation of the working volume, to independently regulate the flow of fluid to the first, second and third high-pressure manifolds.

3. The hydraulic pump apparatus of claim 1 or 2, wherein the hydraulic pump apparatus comprises a controller configured to actively control the low-pressure valves and / or the high-pressure valves of the piston cylinder units to adjust the net displacement of each piston cylinder unit during each rotation of the working volume, to independently regulate the flow of fluid to the first, second and third high-pressure manifolds so that the third cylinder group supplies a lower pressure of hydraulic fluid to the third high-pressure manifold than the first and second cylinder groups supply to the respective first and second high-pressure manifolds, such that the third hydraulic fluid outlet is a dedicated low-pressure outlet for supplying hydraulic fluid to a hydraulic slew motor of the working vehicle.

4. The hydraulic pump apparatus of claim 1, 2 or 3, wherein the hydraulic pump apparatus is configured so that the third cylinder group is able to supply a lower pressure of hydraulic fluid to the third high-pressure manifold than the first and second cylinder groups supply to the respective first and second high-pressure manifolds.

5. The hydraulic pump apparatus of claim 3 or 4, wherein the third high-pressure manifold has an operating pressure in the range 100 bar to 300 bar; and / or wherein the first and second high-pressure manifolds have an operating pressure in the range 100 bar to around 400 bar.

6. The hydraulic pump apparatus of claim 3, 4 or 5, wherein the first and second high-pressure manifolds have an operating pressure which is greater than the operating pressure of the third high-pressure manifold by an amount in the range 50 bar to 150 bar, for example in the range 75bar to 125 bar, for example approximately 100 bar.

7. The hydraulic pump apparatus of any preceding claim, wherein each of the first, second and third cylinder groups comprises a plurality of piston cylinder units.

8. The hydraulic pump apparatus of any preceding claim, wherein the third cylinder group comprises fewer piston cylinder units than the first and / or second cylinder groups.P610252PC009. The hydraulic pump apparatus of claim 8, wherein the hydraulic pump apparatus comprises 30 piston cylinder units, and wherein the third cylinder group comprises nine or ten piston cylinder units.

10. The hydraulic pump apparatus of any preceding claim, wherein the hydraulic pump apparatus comprises a radial piston arrangement in which the plurality of piston cylinder units extend approximately radially and are arranged circumferentially around the drive shaft.

11. The hydraulic pump apparatus of claim 10, wherein the plurality of piston cylinder units comprises a first cylinder ring of piston cylinder units positioned proximal to a first axial position along the drive shaft, and a second cylinder ring of piston cylinder units positioned proximal to a second axial position along the drive shaft, wherein the second axial position is spaced apart from the first axial position.

12. The hydraulic pump apparatus of claim 11, wherein the hydraulic fluid inlet, first hydraulic fluid outlet, second hydraulic fluid outlet and / or third hydraulic fluid outlet pass through the housing between the first and second axial positions.

13. The hydraulic pump apparatus of claim 11 or 12, wherein the piston cylinder units of the first cylinder group are provided in the first cylinder ring, and the piston cylinder units of the second cylinder group are provided in the second cylinder ring.

14. The hydraulic pump apparatus of claim 13, wherein the piston cylinder units of the third cylinder group are provided in one of the first and second cylinder rings.

15. The hydraulic pump apparatus of claim 13, wherein at least one piston cylinder unit of the third cylinder group is provided in the first cylinder ring and wherein at least one piston cylinder unit of the third cylinder group is provided in the second cylinder ring.

16. The hydraulic pump apparatus of any of claims 10 to 15, wherein the piston cylinder units are arranged in cylinder sets each comprising two or more piston cylinder units (e.g., three piston cylinder units), wherein the cylinder sets are arranged circumferentially around the drive shaft and spaced apart from each other such that each piston cylinder unit is closer to piston cylinder units within the same cylinder set than to piston cylinder units of adjacent cylinder sets.P610252PC0017. The hydraulic pump apparatus of claim 16, wherein the cylinder sets each comprise three piston cylinder units and wherein the hydraulic pump apparatus comprises five cylinder sets arranged circumferentially around the drive shaft; optionally, wherein the hydraulic pump apparatus comprises five cylinder sets arranged circumferentially around a first axial position along the drive shaft, and five cylinder sets arranged circumferentially around a second axial position along the drive shaft.

18. A working vehicle comprising:a machine body,a ground engaging propulsion structure coupled to the machine body for moving the working vehicle over a ground surface;a working arm coupled to the machine body for performing a work function; a prime mover for driving movement of the ground-engaging propulsion structure and / or working arm;a first actuator group comprising one or more hydraulic actuators, and a first control valve group for directing hydraulic fluid to the first actuator group;a second actuator group comprising one or more hydraulic actuators, and a second control valve group for directing hydraulic fluid to the second actuator group;a third actuator group comprising one or more hydraulic actuators, and a third control valve group for directing hydraulic fluid to the third actuator group;a hydraulic fluid reservoir; anda hydraulic pump apparatus comprising:a drive shaft coupled to the prime mover for rotation by the prime mover; one or more low-pressure manifolds fluidly connected to the hydraulic fluid reservoir;a first high-pressure manifold fixedly connected to the first control valve group;a second high-pressure manifold fixedly connected to the second control valve group;a third high-pressure manifold fluidly connected to the third control valve group;a plurality of piston cylinder units each comprising: a cylinder which defines a working volume therein; a piston which is driven by the drive shaft and which reciprocates within the cylinder to vary the working volume; a low-pressure valve for controlling flow of hydraulic fluid between the low-pressure manifold and the working volume; and a high-pressure valve for controlling flow of hydraulic fluid from the working volume to one of the first to third high-pressure manifolds; wherein the plurality of piston cylinder units comprises:27P610252PC00a first cylinder group comprising one or more of the piston cylinder units, wherein the high-pressure valve of each piston cylinder unit of the first cylinder group is fixedly connected to the first high-pressure manifold;a second cylinder group comprising one or more of the piston cylinder units, wherein the high-pressure valve of each piston cylinder unit of the second cylinder group is fixedly connected to the second high- pressure manifold; anda third cylinder group comprising one or more of the piston cylinder units, wherein the high-pressure valve of each piston cylinder unit of the third cylinder group is fixedly connected to the third high-pressure manifold.

19. The working vehicle of claim 18, wherein the first to third high-pressure manifolds of the hydraulic pump apparatus are independently connected to the respective first to third control valve groups so that each high-pressure manifold only supplies hydraulic fluid to a single one of the first to third control valve groups.

20. The working vehicle of claim 18 or 19, wherein the machine body comprises an undercarriage supported on the ground-engaging propulsion structure and a superstructure which is configured to rotate relative to the undercarriage about a vertical axis, wherein the first and second actuator groups comprise hydraulic actuators associated with the ground-engaging propulsion structure and / or actuation of the working arm, and wherein the third actuator group comprises a hydraulic slew actuator configured to rotate the superstructure relative to the undercarriage.

21. The working vehicle of claim 20, wherein the third actuator group comprises only the hydraulic slew actuator, such that the third high-pressure manifold is a dedicated hydraulic fluid supply for the hydraulic slew actuator.

22. The working vehicle of claim 20 or 21, wherein the working vehicle is configured so that the third cylinder group is able to supply a lower pressure of hydraulic fluid to the third high-pressure manifold than the first and second cylinder groups supply to the respective first and second high-pressure manifolds; optionally, wherein the third high-pressure manifold has an operating pressure in a range of 100 to 300 bar; and / or optionally, wherein the first and second high-pressure manifolds have an operating pressure in a range of 100 to 400 bar; and / or optionally, wherein the first and second high-pressure manifolds have an operating pressure which is greater than the operating pressure of the third high-pressure manifold by an amount in the range 50 bar to 150 bar, for example in the range 75bar to 125 bar, for example approximately 100 bar.28P610252PC0023. The working vehicle of any of claims 18 to 22, wherein the first actuator group comprises: a first track motor for driving a first track of the ground-engaging propulsion structure; and / or a boom actuator for raising or lowering a boom of the working arm; and / or an implement actuator for actuating an implement of the working arm.

24. The working vehicle of any of claims 18 to 23, wherein the second actuator group comprises: a second track motor for driving a second track of the ground-engaging propulsion structure; and / ora dipperarm actuator for pivoting a dipperarm of the working arm relative to the boom of the working vehicle; and / or an auxiliary actuator port for connecting one or more auxiliary actuators to the second high-pressure manifold.

25. The working vehicle of any of claims 18 to 24, wherein the hydraulic pump apparatus is a hydraulic pump apparatus according to any of claims 1 to 17.29

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