Patent Description:
Working vehicles such as excavators, backhoe loaders, telehandlers, skid-steer loaders, dumpers and the like often have one or more hydraulically actuated devices such as working arm actuators, track motors, bucket actuators etc. Such hydraulically actuated devices operate by receiving a flow of hydraulic fluid from a hydraulic pump.

Typically, the hydraulic pump of a working vehicle receives hydraulic fluid from the reservoir via a first pipe and supplies hydraulic fluid to a hydraulic system via a second pipe. When the hydraulic pump is to be removed/replaced for maintenance or repair, the first and second pipes are disconnected and the hydraulic pump is de-mounted from the working vehicle. Such an arrangement is therefore time-consuming and awkward to maintain and replace. Furthermore, energy losses along the length of the first pipe reduce the efficiency of the hydraulic system.

In standard working vehicles driven by an internal combustion engine (ICE), the hydraulic pump is typically driven by the ICE. That is, the hydraulic pump includes a drive shaft which is coupled (either directly, or via a gearbox) to an output shaft of the ICE, so that the hydraulic pump outputs a flow of hydraulic fluid whenever the ICE is running.

Since a flow of hydraulic fluid is not required by the hydraulically actuated device(s) of the working vehicle at all times when the ICE is running, excess output from the hydraulic pump is returned to the hydraulic reservoir via a bypass circuit/relief valve. Alternatively, a swash angle of the pump is altered to reduce the output of hydraulic fluid from the hydraulic pump. In either case, the ICE-driven pump arrangement leads to reduced efficiency of the hydraulic system, since the pump is being driven unnecessarily when no flow of hydraulic fluid is required. Prior art is disclosed in <CIT>.

The present disclosure seeks to overcome, or at least mitigate, one or more problems of the prior art.

Mounting the pump module(s) (i.e. as attachable/detachable self-contained units) to the housing provides a self-contained pumping assembly and reduces or removes the length of piping needed to connect the pump(s) to fluid (e.g. hydraulic fluid) contained in the tank. This reduces the complexity of the system and reduces or removes energy losses which would occur along such piping. This is particularly beneficial for working vehicles, such as battery-powered working vehicles where reduced energy losses result in increased battery life, or fuel cell powered working vehicles where reduced energy losses result in reduced fuel consumption.

In addition, this arrangement is more compact than prior art systems in which the pump(s) are provided separate from the tank.

Furthermore, having pump modules (i.e. attachable/detachable self-contained units) allows the pump modules to be installed or removed from the pump system without having to connect/disconnect interconnected components within the module. This simplifies the procedure for removal/replacement of pumps for repair or maintenance.

Optionally, the pump system is a hydraulic pump system for supplying hydraulic fluid from the tank to a hydraulic system.

Optionally, the pump system comprises a plurality of pumps, optionally three pumps. Having a plurality of pumps allows fluid (e.g. hydraulic fluid) to be supplied to multiple circuits more efficiently than if a single pump and flow sharing valves were used. Optionally, the mounting arrangement comprises a single mounting portion (e.g. mounting plate) and each pump is mounted to the housing via the single mounting portion.

Having such a single mounting portion provides a simple means to install/remove the pumps together from the housing (e.g. for access to an interior of the housing for cleaning/maintenance).

Optionally, the mounting portion (e.g. mounting plate) comprises a lid for the housing. Optionally, the mounting arrangement comprises a plurality of mounting portions and each pump is mounted to the housing via one of the mounting portions Optionally, the or each pump module comprises a mounting portion and is mounted to the housing by said mounting portion.

Optionally, the or each pump comprises a body, and wherein the body extends at least partially into the tank.

Having a body of the pump(s) extending at least partially into the tank (i.e. into an interior region defined by the housing) provides a compact arrangement (since at least part of the body of the pump is within an interior of the housing) which is useful in space-constrained environments, such as mobile vehicles (e.g. working vehicles).

According to the invention the housing comprises an outer casing and an inner liner spaced apart from the outer casing to define a cavity therebetween.

Such a cavity in a two-part housing reduces the transmission of sound generated by the one or more pumps from within the tank to an exterior of the housing. It will be understood that the liner of such a housing defines an interior wall of the tank.

Optionally, the cavity contains sound absorbing material.

Such sound absorbing material further reduces the amount of noise generated by the one or more pumps that is transmitted to the exterior of the tank.

Optionally, the outer casing comprises an inwardly extending projection (e.g. flange) and/or the inner liner comprises an outwardly extending projection (e.g. flange) configured to space the liner from the outer casing.

Such projection(s) facilitate correct alignment of the inner liner within the casing (e.g. so that a width of the cavity is approximately equal around a perimeter of the housing). Furthermore, such projection(s) being provided on the outer casing and/or inner liner removes the need for separate spacing components.

Optionally, one or more spacers are provided within the cavity between the inner liner and the outer casing.

Such spacer(s) facilitate correct alignment of the inner liner within the casing (e.g. so that a width of the cavity is approximately equal around a perimeter of the housing).

Optionally, the outer casing comprises an open end comprising a rim and the inner liner comprises an end comprising an outwardly extending projection (e.g. flange) for engaging the rim.

Such an arrangement provides a simple means for constructing the two-part housing.

Optionally, the rim comprises an inwardly extending projection (e.g. flange), and the outwardly extending projection of the inner liner engages the inwardly extending projection of the outer casing.

In this way, the inwardly-extending projection of the outer casing acts to space the liner from an outer wall of the outer casing, whilst also provided a greater surface area for contact with the outwardly extending projection of the inner liner (e.g. to provide an increased surface area for welding or for receiving one or more bolts therethrough).

Optionally, the outer casing is formed of plastics material or metallic material (e.g. steel or aluminium).

Optionally, the inner liner is formed of plastics material or metallic material (e.g. steel or aluminium).

The housing components can be easily formed from such materials. These materials have also been found to be suitable for reducing noise in tanks in combination with the cavity and/or sound absorbing material above.

Optionally, the housing defines one or more apertures for receiving the one or more pump modules.

Having one or more apertures for receiving the pump modules, provides a simple means for mounting the pump modules to the housing.

Optionally, the mounting arrangement comprises one or more plates or flanges each for at least partially surrounding a perimeter of one of said one or more apertures of the housing.

Having a plate or flange which surrounds a perimeter of one of said apertures of the housing allows the aperture to be completely covered by the plate or flange (which is useful for preventing ingress of dirt or debris, and/or leakage of fluid from the aperture). Such a plate or flange also provides an abutment surface which indicates when the pump module has been correctly positioned relative to the housing.

Optionally, the mounting arrangement (e.g. a single mounting plate, or a plurality of mounting plates/flanges) is mounted to the housing via a releasable fastening.

Having a releasable fastening allows the pump module(s) to be easily removed/installed for maintenance or replacement purposes.

Optionally, one of the mounting arrangement and housing comprises one or more through-holes or threaded holes and the other of the mounting portion and housing comprises a corresponding one or more threaded holes or through-holes, wherein the or each through-hole and threaded hole is provided for receiving a bolt to couple said mounting arrangement to the housing.

Having an arrangement which is suitable for coupling via one or more bolts provides a simple means of releasably mounting the pump module(s) to the housing via the mounting arrangement.

Optionally, the pump system further comprises one or more seals for sealing the one or more apertures.

The apertures being sealed allows the pump assembly to be used in any orientation (e.g. pump modules can be mounted on a top, side or lower surface of the housing) without leakage of fluid (e.g. hydraulic fluid). This provides a more flexible range of uses for the pump assembly. Furthermore, being sealed also prevents leakage in mobile applications where fluid may move around within the tank (e.g. in a working vehicle due to acceleration forces or inclined surfaces).

Optionally, the mounting arrangement comprises one or more mounting plates or flanges which at least partially surround a respective aperture of said one or more apertures of the housing, and wherein the or each mounting plate or flange further comprises a seal surface and/or seal provided on said mounting plate or flange for sealing said aperture.

A seal (e.g. a compressible seal such as a gasket) offers a reliable means of sealing an aperture, particularly under pressure (e.g. a bolting pressure exerted on the compressible seal when the mounting portion is secured to the housing via one or more bolts).

Optionally, each of the one or more pump modules comprises a body comprising an inlet portion which defines a pump inlet, and.

Having a pump inlet of the pump body immersed in fluid (e.g. hydraulic fluid) in the tank removes the need for pipework connecting the pump inlet to the fluid in the tank. This reduces the complexity of the system and reduces or removes energy losses which would occur along such piping. This is particularly beneficial for working vehicles, such as battery-powered working vehicles where reduced energy losses result in increased battery life, or fuel cell powered working vehicles where reduced energy losses result in reduced fuel consumption.

Optionally, each of the one or more pump modules comprises a pump outlet, and wherein the hydraulic pump system further comprises one or more fluid supply lines (e.g. hydraulic supply lines) connected to the one or more pump outlets for channelling fluid (e.g. hydraulic fluid) supplied by the one or more pump modules out of the housing.

Such a fluid supply line(s) allows fluid (e.g. hydraulic fluid) supplied by the pump(s) to be used outside the tank (e.g. to move actuators in a hydraulic system for a working vehicle).

Optionally, each of the fluid supply lines is coupled to the mounting arrangement, so that said fluid supply lines can be attached/detached from the pump system with the respective pump modules.

Each of the fluid supply lines being coupled to the mounting arrangement allows simple removal/replacement of pump modules with the mounting arrangement without having to connect/disconnect the fluid supply line from the associated pump outlet.

Optionally, the mounting arrangement comprises one or more fluid supply ports each coupled to a respective fluid supply line for connection to a fluid system (e.g. hydraulic system) in order to supply fluid (e.g. hydraulic fluid) from the pump module to the fluid system, wherein the fluid supply port is arranged to be external to the tank.

Such a fluid supply port allows the pump module(s) to be easily connected to a fluid system (e.g. to a hydraulic system for moving hydraulic actuators in a hydraulic system for a working vehicle).

Furthermore, the one or more fluid supply ports being provided on or by the mounting arrangement allows the pump(s) to be removed with the mounting arrangement without having to disconnect the fluid supply line(s) and/or downstream fluid connections (e.g. as opposed to having the port(s) on a fixed part of the housing, which would necessitate disconnecting the fluid supply line(s) from the respective port(s) and/or pump(s) when removing the pump(s) and mounting arrangement from the housing.

Optionally, each of the one or more pump modules further comprises an electric motor for driving the pump.

In embodiments with multiple pump modules, having an electric motor for each pump module allows flow of fluid from each module to be controlled independently of the other modules. This allows optimal pump flow rates to be set for each pump module, in contrast to prior art hydraulic systems that are driven by an internal combustion engine (ICE) which results in the hydraulic pump(s) outputting hydraulic fluid whenever the ICE is running (even if not required by hydraulically actuated devices of the hydraulic system). In other words, having an electric motor for each pump module leads to improved efficiency of the pump system, which is particularly beneficial for working vehicles, such as battery-powered working vehicles where increased pump system efficiency results in increased battery life, or fuel cell powered working vehicles where reduced energy losses result in reduced fuel consumption.

Optionally, the output of fluid (e.g. hydraulic fluid) from the pump of each of the one or more pump modules is controlled via rotation speed of the electric motor of said pump module; optionally, wherein the pump system further comprises one or more inverters for controlling frequency of power supplied to the one or more pump modules; optionally, wherein the one or more inverters are each mounted to the mounting arrangement or to a respective pump module, so that said one or more inverters can be attached/detached from the pump system with said one or more pump modules.

Having the pump(s) controlled via rotation speed of the electric motor(s) allows an optimal pump flow rate to be set for each pump module. This reduces the need for restrictions in downstream fluid systems (e.g. downstream hydraulic systems), which improves the efficiency of the associated fluid system.

Such an inverter arrangement enables variable speed control of the electric motor(s) and DC to AC power smoothing/conversion. This is useful in applications where the electric motors are powered by a DC electricity source (e.g. a battery on an electric working vehicle or a fuel cell on a fuel cell powered working vehicle).

Optionally, the pump system further comprises a controller configured to set the rotation speed of the or each electric motor based on one or more user inputs and/or one or more sensor inputs such as pump pressure and system temperature.

Such a controller allows an optimal pump flow rate to be set for each pump module, which leads to increased efficiency of a fluid system (e.g. hydraulic system) incorporating the pump system.

Optionally, the electric motor of each of the one or more pump modules is connected to the pump of said pump module by a common drive shaft or a gearbox.

Connecting a pump to an electric motor via a common drive shaft offers a simple and reliable means for driving the hydraulic pump by the electric motor.

Connecting a pump to an electric motor via a gearbox allows the electric motor and pump to each be run in their optimal rotational speed ranges (which may differ), which increases the efficiency of the pump system.

Optionally, the electric motor and/or inverter of at least one of the one or more pump modules is arranged to be positioned external to the tank.

Arranging the electric motor(s) to be external to the tank protects electrical components from short-circuiting or other damage caused be contact with hydraulic fluid.

Optionally, the pump system comprises a cover for said electric motor(s) and/or inverter(s).

Such a cover provides two functions. Firstly, the cover protects the external components (i.e. electric motor(s) and/or inverter(s)) from being damaged by impact or dirt/debris. Secondly, the cover reduces the transmission of noise generated by the external components, which results in a quieter pump system.

Optionally, the cover comprises sound-absorbing material (e.g. lined on an inside of the cover).

Such sound-absorbing material further reduces the transmission of noise from the pump system.

Optionally, the cover is formed of plastics material or metallic material (e.g. steel or aluminium).

The cover can be easily formed from such materials. These materials have also been found to be suitable for reducing noise transmission through the cover.

Optionally, the pump of each of the one or more pump modules is a fixed displacement pump.

Having an electric motor driving a fixed displacement pump eliminates the need for variable swash control to vary pump output, which allows an infinite range of output flow rates without inefficiency of partial displacement associated with variable swash plate piston pumps.

Optionally, the pump of each of the one or more pump modules is a bent axis piston pump.

Bent axis piston pumps have been found to offer a high displacement ratio due to large swash angles (><NUM>°), which results in a power dense package in comparison to axial piston pumps. This provides a high volumetric efficiency, which leads to an increased overall efficiency of the pump system.

Optionally, the pump system further comprises a filter arrangement for filtering fluid (e.g. hydraulic fluid) input to the tank (e.g. hydraulic fluid returning to the tank from a hydraulic system).

Having such a filter arrangement removes debris entrained in the fluid prior to entering the tank (e.g. debris formed via erosion of components in a hydraulic system) which improves the efficiency of the associated fluid system and reduces the likelihood of damage to components such as the pump.

Optionally, the filter arrangement is mounted on the housing or the mounting arrangement; optionally, wherein the filter arrangement extends at least partially into the tank.

Having the filter arrangement mounted on the housing and extending into the tank provides a compact and self-contained arrangement.

According to a second aspect of the disclosure, a working vehicle is provided, the working vehicle comprising a pump system as disclosed herein.

Optionally, the working vehicle is an electric working vehicle (e.g. a battery powered working vehicle).

Optionally, the working vehicle is a fuel cell powered working vehicle (e.g. comprising a hydrogen fuel cell for powering the working vehicle).

Optionally, the working vehicle is a hybrid working vehicle of the kind having an electric source of power and an alternative source of power.

The pump system of the first aspect of the disclosure is particularly compact and efficient. This provides significant benefits when applied to a working vehicle (where space is restricted and power is of limited capacity), particularly electric working vehicles where increased efficiency results in increased battery life and periods of use between charging, or fuel cell powered working vehicles where reduced energy losses result in reduced fuel consumption.

Optionally, the working vehicle is an excavator, backhoe loader, telehandler, skid-steer loader, dumper, forklift truck or other type of working vehicle having one or more hydraulically-actuated devices.

According to a third aspect of the disclosure, a pump module is provided, the pump module comprising a pump, an electric motor for driving the pump, and a mounting portion for mounting the pump module to a housing of a fluid tank in use.

Such a pump module (i.e. an attachable/detachable self-contained unit) is suitable for mounting directly to a housing of a fluid tank, which provides a compact arrangement. Furthermore, such an arrangement allows easy removal/replacement/maintenance of such modules.

Optionally, the pump is a hydraulic pump.

Optionally, the mounting portion is positioned such that a portion of the pump extends into said fluid tank when the pump module is mounted to said housing by the mounting portion in use.

Optionally, the mounting portion comprises a flange for surrounding a perimeter of an aperture of said housing when the pump module is mounted to said housing by the mounting portion in use.

Having a flange which surrounds a perimeter of an aperture of the housing allows the aperture to be completely covered by the mounting portion (which is useful for preventing ingress of dirt or debris, and/or leakage of fluid from the aperture). Such a flange also provides an abutment surface which indicates when the pump module has been correctly positioned relative to the housing.

Optionally, the mounting portion comprises a releasable fastening for releasably mounting the hydraulic pump module to said housing in use.

Having a releasable engagement formation provides a simple means of releasably mounting the pump module to the housing. This allows the pump module to be removed for maintenance or replaced easily.

Optionally, the mounting portion comprises a seal surface and/or seal configured to seal an aperture of said housing when the pump module is mounted to said housing by the mounting portion in use.

A seal (e.g. a compressible seal such as a gasket) offers a reliable means of sealing an aperture, particularly under pressure (e.g. a bolting pressure exerted on the compressible seal when the mounting portion is secured to the housing via one or more bolts). Furthermore, this allows the pump module to be fitted a housing of a fluid tank in any orientation (e.g. to a top, side or bottom surface) without leakage of fluid (e.g. hydraulic fluid).

Optionally, the electric motor is arranged to be positioned external to said fluid tank when the pump module is mounted to said housing by the mounting portion in use.

Arranging the electric motor to be external to the tank in use protects electrical components from short-circuiting or other damage caused be contact with fluid.

Optionally, the pump comprises a pump inlet and a pump outlet, wherein the pump module further comprises a fluid supply line connected to the pump outlet for channelling fluid (e.g. hydraulic fluid) supplied by the pump to a fluid system (e.g. a hydraulic system).

Having a fluid supply line as part of the pump module allows simple removal/replacement of the pump module from a housing of a tank without having to connect/disconnect the fluid supply line from the pump outlet.

Optionally, the fluid supply line is coupled to the mounting portion, so that said hydraulic supply lines can be attached/detached from said housing with the pump.

The fluid supply line being coupled to the mounting portion allows simple removal/replacement of the pump module without having to connect/disconnect the fluid supply line from the pump outlet.

Optionally, the mounting portion further comprises a fluid supply port coupled to the fluid supply line for connection to a fluid system (e.g. hydraulic system) in order to supply fluid from the pump module to the fluid system, wherein the fluid supply port is arranged to be external to said fluid tank when the pump module is mounted to said housing by the mounting portion in use.

Having a fluid supply port allows the pump module to be easily connected to a fluid system (e.g. a hydraulic system for moving hydraulic actuators of a working vehicle).

Optionally, the output of fluid from the pump is controlled via rotation speed of the electric motor.

Having the pump controlled via rotation speed of the electric motor allows an optimal pump flow rate to be set for the pump module. This reduces the need for restrictions in downstream fluid systems (e.g. valves in hydraulic circuits), which improves the efficiency of the associated fluid system.

Optionally, the pump module further comprises an inverter to control frequency of power supplied to the electric motor.

Having an inverter arrangement enables variable speed control of the electric motor(s) and DC to AC power smoothing/conversion. This is useful in applications where the electric motors are powered by a DC electricity source (e.g. a battery on an electric working vehicle, or a fuel cell in a fuel cell powered working vehicle).

Optionally, the electric motor is connected to the pump by a common drive shaft or a gearbox.

Connecting the pump to the electric motor via a common drive shaft offers a simple and reliable means for driving the pump by the electric motor.

Connecting the pump to the electric motor via a gearbox allows the electric motor and pump to each be run in their optimal rotational speed ranges (which may differ), which increases the efficiency of the pump module.

Optionally, the pump is a fixed displacement pump.

Optionally, the pump is a bent axis piston pump.

Bent axis piston pumps have been found to offer a high displacement ratio due to large swash angles (><NUM>°), which results in a power dense package in comparison to axial piston pumps. This provides a high volumetric efficiency, which leads to an increased overall efficiency of the pump module.

According to a fourth aspect of the disclosure, a pump module is provided, the pump module comprising a pump and a mounting portion for mounting the pump module to a housing of a hydraulic fluid tank in use, wherein the mounting portion is configured to at least partially surround an aperture of said housing, and wherein the mounting portion comprises a seal surface and/or seal configured to seal said aperture when the pump module is mounted to said housing in use.

Such a pump module (i.e. an attachable/detachable self-contained unit) is suitable for mounting directly to a housing of a hydraulic fluid tank, which provides a compact arrangement. Furthermore, such an arrangement allows easy removal/replacement/ maintenance of such modules.

In addition, a seal (e.g. a compressible seal such as a gasket) offers a reliable means of sealing an aperture, particularly under pressure (e.g. a bolting pressure exerted on the compressible seal when the mounting portion is secured to the housing via one or more bolts).

Optionally, the mounting portion comprises a flange for surrounding a perimeter of said aperture when the pump module is mounted to said housing by the mounting portion in use;.

Having a flange which surrounds a perimeter of an aperture of the housing allows the aperture to be completely covers by the mounting portion (which is useful for preventing ingress of dirt or debris, and/or leakage of fluid from the aperture). Such a flange also provides an abutment surface which indicates when the pump module has been correctly positioned relative to the housing.

Optionally, the mounting portion comprises a releasable fastening for releasably mounting the pump module to said housing in use.

Having a releasable engagement allows the pump module to be easily removed/installed to a housing for maintenance or replacement purposes.

According to a further aspect of the disclosure a fluid system is provided, the fluid system comprising:.

Such a cavity in a two-part housing reduces the transmission of sound generated by the one or more components from within the tank to an exterior of the housing. For example, where the one or more components are pumps, any noise generated by the pumps would be reduced by the two-part tank construction. It will be understood that the liner of such a housing defines an interior wall of the tank.

Such sound absorbing material further reduces the amount of noise generated by the one or more components that is transmitted to the exterior of the tank.

Such an arrangement provides a simple means for constructing the two-part housing. Optionally, the rim comprises an inwardly extending projection (e.g. flange), and the outwardly extending projection of the inner liner engages the inwardly extending projection of the outer casing.

In this way, the inwardly-extending projection of the outer casing acts to space the liner from an outer wall of the outer casing, whilst also provided a greater surface area for contact with the outwardly extending projection of the inner liner (e.g. to provide an increased surface area for welding or for receiving one or more bolts therethrough). Optionally, the outer casing is formed of plastics material or metallic material (e.g. steel or aluminium).

Embodiments are now described by way of example only with reference to the accompanying drawings, in which:.

Referring firstly to <FIG>, a hydraulic pump system is indicated at <NUM>. The hydraulic pump system <NUM> includes a housing <NUM> defining a tank <NUM> for containing hydraulic fluid <NUM> in use. In the illustrated embodiment, the hydraulic pump system also includes three pump modules <NUM> (one of which is obscured by the exploded/removed pump module <NUM> at the front of the figure). In alternative embodiments, more or fewer than three pump modules <NUM> are provided.

Each pump module <NUM> includes a mounting portion <NUM> and a hydraulic pump <NUM> for supplying hydraulic fluid <NUM> from the tank <NUM> to a hydraulic system (e.g. a hydraulic system of a working vehicle).

Each pump module <NUM> is mounted to the housing <NUM> by the mounting portion <NUM>. Having pump modules <NUM> (i.e. attachable/detachable self-contained units) mounted to the housing <NUM> provides a self-contained hydraulic pump system <NUM> and reduces or removes the length of piping needed to connect the pumps <NUM> to the hydraulic fluid <NUM> contained in the tank <NUM>. This reduces the complexity of the system and reduces or removes energy losses which would occur along such piping. This is particularly beneficial for working vehicles, such as battery-powered working vehicles where reduced energy losses result in increased battery life, or fuel cell powered working vehicles where reduced energy losses result in reduced fuel consumption. In addition, this arrangement is more compact than prior art systems in which the hydraulic pump(s) <NUM> are provided separate from the tank <NUM>.

It will be understood that the pump modules <NUM> are each attachable to and detachable from the housing as a self-contained unit. In other words, the pump modules <NUM> can each be installed or removed from the hydraulic pump system <NUM> without having to connect/disconnect interconnected components within the pump module <NUM>.

Each hydraulic pump <NUM> includes a body <NUM> having a pump inlet <NUM> and a pump outlet <NUM>. In the illustrated embodiment, the body <NUM> extends into the tank <NUM> so that the pump inlet <NUM> is immersed in hydraulic fluid <NUM> contained in the tank <NUM> in use. In alternative embodiments, the body <NUM> extends partially into the tank <NUM>. For example, in some embodiments part of the body <NUM> (e.g. an inlet portion) extends into the tank and another part of the body <NUM> is located external to the tank <NUM>. In some embodiments, the pump inlet <NUM> is not immersed in hydraulic fluid <NUM> contained in the tank <NUM> in use. Having a body <NUM> extending at least partially into the tank <NUM> (i.e. into an interior region defined by the housing <NUM>) provides a compact arrangement, since at least part of the body <NUM> of the hydraulic pump <NUM> is within an interior of the housing <NUM>, which is useful in space-constrained environments, such as mobile vehicles (e.g. working vehicles).

The housing <NUM> defines three apertures <NUM> for receiving the pump modules <NUM>. The mounting portion <NUM> of each pump module <NUM> is configured for mounting the pump module <NUM> around a respective aperture <NUM> of the housing <NUM>. It will therefore be understood that where the number of pump modules <NUM> is more or less than in the illustrated embodiment, the number of apertures <NUM> differs accordingly. Having one or more apertures <NUM> for receiving the pump modules <NUM>, and a mounting portion <NUM> on each pump module <NUM> provides a simple means for mounting the pump modules <NUM> to the housing <NUM>.

In the illustrated system the mounting portion <NUM> of each pump module <NUM> includes a flange <NUM> for surrounding a perimeter of an aperture <NUM> of the housing <NUM> when the pump module <NUM> is coupled to the housing <NUM> in use. Having a flange <NUM> which surrounds a perimeter of an aperture <NUM> of the housing <NUM> allows the aperture <NUM> to be completely covered by the mounting portion <NUM> (which is useful for preventing ingress of dirt or debris, and/or leakage of fluid from the aperture <NUM>). Such a flange <NUM> also provides an abutment surface which indicates when the pump module <NUM> has been correctly positioned relative to the housing <NUM>.

In alternative variants, the mounting portion <NUM> of each pump module <NUM> includes a flange which only partially surrounds a perimeter of an aperture <NUM> of the housing <NUM>. In alternative embodiments, the mounting portion <NUM> includes a plurality of projections or flanges arranged circumferentially around an aperture <NUM> of the housing <NUM> in use.

In the illustrated variant, the mounting portion <NUM> of each pump module <NUM> is mounted to the housing <NUM> via a releasable fastening. Having a releasable fastening allows the pump modules <NUM> to be easily removed/installed for maintenance or replacement purposes.

In particular, the mounting portion <NUM> includes a plurality of through-holes <NUM> and the housing <NUM> includes a corresponding plurality of threaded holes <NUM>. Each through-hole <NUM> and threaded hole <NUM> is provided for receiving a bolt (not shown) to couple the pump module <NUM> to the housing <NUM> in use. In alternative embodiments, the housing <NUM> includes a plurality of through-holes <NUM> and the mounting portion <NUM> includes a corresponding plurality of threaded holes <NUM>. In alternative embodiments, any other combination of through-holes and/or threaded holes suitable for receiving a fastener is used (e.g. a plurality of through-holes on the housing <NUM> and a corresponding plurality of through-holes on the mounting portion <NUM>, or a plurality of threaded holes on the housing <NUM> and a corresponding plurality of threaded holes on the mounting portion <NUM>). It will be understood that the term "through-hole" shall be interpreted as a non-threaded hole, and the term "threaded hole" shall be interpreted as a blind or through-hole comprising threads. Having an arrangement which is suitable for coupling via one or more bolts provides a simple means of releasably mounting the pump modules <NUM> to the housing <NUM>.

In alternative variants, the mounting portion <NUM> of each pump module <NUM> is fixedly attached to the housing <NUM> (e.g. via welding or adhesive). Fixedly attaching the mounting portions <NUM> to the housing <NUM> ensures a robust connection and can contribute to sealing of the apertures <NUM> in which the pump modules <NUM> are received.

As will be described in more detail below, the hydraulic pump system <NUM> includes seals for sealing the apertures <NUM> to prevent leakage of hydraulic fluid <NUM> from the tank <NUM>. The apertures <NUM> being sealed in use allows the hydraulic pump system <NUM> to be used in any orientation (e.g. pump modules <NUM> can be mounted on a top, side or lower surface of the housing <NUM>) without leakage of hydraulic fluid <NUM>. This provides a more flexible range of uses for the hydraulic pump system <NUM>. Furthermore, being sealed also prevents leakage in mobile applications where hydraulic fluid <NUM> may move around within the tank <NUM> (e.g. in a working vehicle due to acceleration forces or travelling over inclined surfaces).

In the illustrated variant, the mounting portion <NUM> of each pump module <NUM> includes a seal <NUM> for sealing a respective aperture <NUM> when the pump module <NUM> is coupled to the housing <NUM> in use. A seal <NUM> (e.g. a compressible seal such as a gasket) offers a reliable means of sealing an aperture <NUM>, particularly under pressure (e.g. a bolting pressure exerted on the compressible seal <NUM> when the mounting portion <NUM> is secured to the housing <NUM> via one or more bolts).

In the illustrated variant, the seal <NUM> of each pump module <NUM> is provided on a lower surface of the mounting portion <NUM>, so that the seal <NUM> is provided between the flange <NUM> and a portion of the housing <NUM> surrounding the aperture <NUM>.

In alternative variants, the mounting portion <NUM> of each pump module <NUM> includes a seal surface instead of, or in addition to, the seal <NUM>. For example a flat metal surface intended to form a metal-to-metal seal with the housing when the mounting portion <NUM> is fixed to the housing under pressure (e.g. bolting pressure).

The hydraulic pump system <NUM> also includes a plurality of hydraulic supply lines <NUM> each connected to a respective pump outlet <NUM> of the pump modules <NUM> for channelling hydraulic fluid <NUM> supplied by the pump modules <NUM> out of the housing <NUM>. Such hydraulic supply lines <NUM> allow hydraulic fluid <NUM> supplied by the hydraulic pumps <NUM> to be used outside the tank <NUM> (e.g. to move actuators in a hydraulic system for a working vehicle).

In the illustrated variant, each pump module <NUM> includes one of the hydraulic supply lines <NUM> so that the hydraulic supply lines <NUM> can be attached/detached from the hydraulic pump system <NUM> with the respective pump module <NUM>. Each of the hydraulic supply lines <NUM> being part of a respective pump module <NUM> allows simple removal/replacement of pump modules <NUM> without having to connect/disconnect the hydraulic supply line <NUM> from the associated pump outlet <NUM>.

In the illustrated variant, each pump module <NUM> includes a hydraulic supply port <NUM> coupled to the hydraulic supply line <NUM> of the pump module <NUM> for connection to a hydraulic system in order to supply hydraulic fluid <NUM> from the pump module <NUM> to the hydraulic system. Each of the hydraulic supply ports <NUM> is arranged to be external to the tank <NUM> when its respective pump module <NUM> is mounted to the housing <NUM>. Such a hydraulic supply port <NUM> allows the hydraulic pump modules <NUM> to be easily connected to a hydraulic system (e.g. for moving hydraulic actuators in a hydraulic system for a working vehicle).

In alternative variants, the hydraulic supply ports <NUM> are provided on the housing <NUM> rather than the respective pump modules <NUM>.

In the illustrated variant, each of the pump modules <NUM> also includes an electric motor <NUM> for driving the hydraulic pump <NUM> of the pump module <NUM>. In embodiments with multiple pump modules <NUM> such as that illustrated, having an electric motor <NUM> for each pump module <NUM> allows flow of hydraulic fluid <NUM> from each module <NUM> to be controlled independently of the other modules <NUM>. This allows optimal pump flow rates to be set for each pump module <NUM>, in contrast to prior art hydraulic systems that are driven by an internal combustion engine (ICE) which results in the hydraulic pump(s) outputting hydraulic fluid whenever the ICE is running (even if not required by hydraulically actuated devices of the hydraulic system). In other words, having an electric motor for each pump module leads to improved efficiency of the hydraulic pump system <NUM>, which is particularly beneficial for working vehicles, such as battery-powered working vehicles where increased pump system efficiency results in increased battery life, or fuel cell powered working vehicles where reduced energy losses result in reduced fuel consumption.

Referring still to <FIG>, the output of hydraulic fluid <NUM> from the hydraulic pump <NUM> of each of the pump modules <NUM> is controlled via rotation speed of the electric motor <NUM> of the pump module <NUM>. Having the hydraulic pumps <NUM> controlled via rotation speed of the electric motors <NUM> allows an optimal pump flow rate to be set for each pump module <NUM>. This reduces the need for restrictions in downstream hydraulic systems, which improves the efficiency of the associated hydraulic system.

In the illustrated variant, the hydraulic system also includes three inverters <NUM> to control frequency of power supplied to the electric motors <NUM> of the pump modules <NUM>. Such an inverter arrangement enables variable speed control of the electric motors <NUM> and DC to AC power smoothing/conversion. This is useful in applications where the electric motors <NUM> are powered by a DC electricity source (e.g. a battery on an electric working vehicle or a fuel cell on a fuel cell powered vehicle).

In some variant, the inverters <NUM> are each part of a respective pump module <NUM> so that the inverter <NUM> can be attached/detached from the hydraulic pump system <NUM> with said pump module <NUM>. In alternative embodiments, the inverters <NUM> are provided separate to the pump modules <NUM>. In alternative embodiments, the electric motors <NUM> are DC motors and the inverters <NUM> are omitted.

The hydraulic pump system <NUM> also includes a controller <NUM> configured to set the rotation speed of the electric motors <NUM> based on one or more user inputs <NUM> (such as an operating lever position) and/or one or more sensor inputs <NUM> (such as pump pressure and system temperature). Such a controller <NUM> allows an optimal pump flow rate to be set for each pump module <NUM>, which leads to increased efficiency of a hydraulic system incorporating the hydraulic pump system <NUM>.

Referring again to <FIG>, the electric motor <NUM> of each pump module <NUM> is connected to the hydraulic pump <NUM> of the pump module <NUM> by a common drive shaft <NUM>. Connecting a hydraulic pump <NUM> to an electric motor <NUM> via a common drive shaft <NUM> offers a simple and reliable means for driving the hydraulic pump <NUM> by the electric motor <NUM>.

In alternative variants, the electric motor <NUM> of each pump module <NUM> is connected to the hydraulic pump <NUM> of the pump module <NUM> by a gearbox. Connecting a hydraulic pump <NUM> to an electric motor <NUM> via a gearbox allows the electric motor <NUM> and hydraulic pump <NUM> to each be run in their optimal rotational speed ranges (which may differ), which increases the efficiency of the hydraulic pump system <NUM>.

In the illustrated variant, the electric motor <NUM> of each pump module <NUM> is arranged so that it is positioned external to the tank <NUM>. Arranging the electric motors <NUM> to be external to the tank <NUM> protects electrical components from short-circuiting or other damage caused be contact with hydraulic fluid <NUM> located within the tank <NUM> in use.

In some variants, the hydraulic pump <NUM> of each pump module <NUM> is a fixed displacement pump. For example, in some embodiments the hydraulic pumps <NUM> are bent axis piston pumps. Having an electric motor <NUM> driving a fixed displacement pump <NUM> eliminates the need for variable swash control to vary pump output, which allows an infinite range of output flow rates without inefficiency of partial displacement associated with variable swash plate piston pumps. Furthermore, bent axis piston pumps have been found to offer a high displacement ratio due to large swash angles (><NUM>°), which results in a power dense package in comparison to axial piston pumps. This provides a high volumetric efficiency, which leads to an increased overall efficiency of the hydraulic pump system <NUM>.

In alternative variants, the number of electric motors <NUM> is less than the number of pump modules <NUM>, so that one or more pump modules are driven by a common electric motor <NUM>. In alternative embodiments, the electric motors <NUM> are omitted and the pump modules <NUM> are driven by an internal combustion engine. In some embodiments where the pump modules <NUM> are driven by an internal combustion engine, the output of hydraulic fluid <NUM> from the hydraulic pumps <NUM> of the pump modules <NUM> is variable for a given rotation rate of the common electric motor <NUM> or internal combustion engine (e.g. by using a variable swash-plate pump). In such embodiments, a controller is provided to set the swash-plate angle (or similar displacement-changing property of the hydraulic pumps) based on one or more user inputs <NUM> and/or sensor inputs <NUM>.

In the illustrated variants, the hydraulic pump system <NUM> also includes a filter arrangement <NUM> for filtering hydraulic fluid <NUM> input to the tank <NUM> (e.g. hydraulic fluid <NUM> returning from one or more hydraulically-actuated devices of a working vehicle). Having such a filter arrangement <NUM> removes debris entrained in the hydraulic fluid <NUM> prior to entering the tank <NUM> (e.g. debris formed via erosion of components in a hydraulic system) which improves the efficiency of the hydraulic system and reduces the likelihood of damage to components such as the hydraulic pump <NUM>. In the illustrated embodiment, the filter arrangement <NUM> is mounted on the housing <NUM> and extends partially into the tank <NUM> similarly to the pump modules <NUM>, which provides a compact and self-contained arrangement. In alternative embodiments, the filter arrangement <NUM> is provided external to the housing <NUM> (e.g. as a separate unit connected to the tank <NUM> via a pipe).

The hydraulic pump system <NUM> may be used in different applications with different pump requirements. For example, in some embodiments only two pump modules <NUM> are required. In some embodiments where only two pump modules <NUM> are required, the housing <NUM> still includes three apertures <NUM> for receiving three pump modules <NUM>. Therefore, one of the apertures <NUM> will not be covered by a pump module <NUM>. In such embodiments, the aperture <NUM> which is not covered by the pump module <NUM> is covered by a cover plate of similar shape and size as the mounting portion <NUM> of the pump modules <NUM>. In this way, the aperture <NUM> which is not covered by a pump module <NUM> is covered (and sealed, if the cover plate includes a seal) to prevent influx of debris to the tank <NUM> or leakage of hydraulic fluid <NUM> from the tank <NUM>. Such a hydraulic pump system <NUM> is therefore configurable to meet the requirements of a particular application, by using the same basic integers (i.e. housing <NUM>, pump modules <NUM> and cover plate).

Referring now to <FIG>, a hydraulic pump system according to an embodiment of the invention is indicated at <NUM>. Common features between the hydraulic pump system of <FIG> and this embodiment are given the prefix "<NUM>", and only differences between the embodiments will be discussed in detail.

The housing <NUM> includes an outer casing 212a and an inner liner 212b which defines an interior wall of the tank <NUM>. The inner liner 212b is spaced apart from the outer casing 212a to define a cavity <NUM> therebetween (as best illustrated in <FIG> and <FIG>). The cavity <NUM> reduces the transmission of sound generated by the pumps <NUM> from within the tank <NUM> to an exterior of the housing <NUM>. In some embodiments, the cavity <NUM> contains sound absorbing material to further reduce the amount of noise generated by the pumps <NUM> that is transmitted to the exterior of the housing <NUM>.

In the embodiment of <FIG>, the outer casing 212a has an open end defining a rim <NUM> and the inner liner 212b has an outwardly extending flange <NUM> for engaging the rim <NUM>. In this way, the outwardly extending flange <NUM> prevents the inner liner 212b from dropping to the base of the outer casing 212a, so that the cavity <NUM> extends underneath the inner liner 212b. In alternative embodiments, the inner liner 212b has a different type of outwardly extending projection instead of the flange <NUM> (e.g. a series of outwardly extending projections distributed around the inner liner 212b).

The rim <NUM> of the outer casing 212a defines an inwardly extending flange which is configured to space the inner liner 212b from the side walls 262a of the outer casing 212a. In this way, the inwardly extending flange of the rim <NUM> extends to and abuts against the side walls 262b of the inner liner 212b, which ensures correct alignment of the inner liner 212b within the outer casing 212a. In alternative embodiments, the rim <NUM> has a different type of inwardly extending projection instead of a flange (e.g. a series of inwardly extending projections distributed around the rim <NUM>).

In alternative embodiments, separate spacing components are provided within the cavity <NUM> to facilitate spacing between the liner 212b and the outer casing 212a (e.g. in addition to, or instead of, the inwardly extending flange/projection(s) of the rim <NUM>).

In the embodiment of <FIG>, the rim <NUM> is box shaped (i.e. formed of box sections welded to the side walls <NUM>) and also extends outwardly from the side walls to provide a greater contact area for the flange <NUM> of the inner liner 212b and for the mounting plate <NUM>. In alternative embodiments, the inwardly extending flange of the rim <NUM> is formed by bending the side walls <NUM> inwards.

The housing has an open upper end which defines an aperture <NUM> for receiving the pumps <NUM>, as will be described in more detail below. The aperture <NUM> is closed by a mounting plate <NUM>. In other words, the mounting plate <NUM> acts as a lid for the tank <NUM>.

The mounting plate <NUM>, flange <NUM> of the inner liner 212b and/or the rim <NUM> of the outer casing 212a can be clamped or welded together. While not shown in the illustrated embodiment, mounting plate <NUM>, flange <NUM> of the inner liner 212b and/or the rim <NUM> of the outer casing 212a can also be attached by fasteners (e.g. bolts) provided in complementary through-holes or threaded holes in the mounting plate <NUM>, flange <NUM> of the inner liner 212b and/or rim <NUM> of the outer casing 212a. It will be understood that in some embodiments with such through-holes or threaded holes, the outwardly extending portion of the rim <NUM> is extended to provide space for the holes to receive the fasteners.

In some embodiments, a seal (not shown) is provided between the mounting plate <NUM> and the housing <NUM>. For example, in some embodiments a compressible seal such as a gasket is attached to an underside of the mounting plate <NUM> or attached to a top of the flange <NUM> of the inner liner 212b. Alternatively, in some embodiments a compressible seal is provided as a separate component that is placed between the mounting plate <NUM> and housing <NUM> during assembly. In some embodiments where a seal is provided between the mounting plate <NUM> and the housing <NUM>, the seal also has holes aligned with through-holes or threaded holes of the mounting plate <NUM> and housing <NUM> to receive a fastener (e.g. bolt) therethrough.

The outer casing 212a can be formed of plastics material, metallic material (e.g. steel or aluminium) or any other suitable material. Similarly, the inner liner 212b can be formed of plastics material, metallic material (e.g. steel or aluminium) or any other suitable material.

In the embodiment of <FIG>, the mounting plate <NUM> is configured to mount all of the pumps <NUM> to the housing <NUM>. In other words, the pump module <NUM> includes the mounting plate <NUM>, the three pumps <NUM>, and their respective motors <NUM> and inverters <NUM>, so that all the pumps <NUM>, motors <NUM> and inverters <NUM> are installed/removed from the housing <NUM> together. The hydraulic supply lines <NUM> each extend from a respective pump outlet <NUM> to a respective port <NUM> provided on the common mounting plate <NUM>.

In alternative embodiments, the pumps <NUM> and their respective motors <NUM> and inverters <NUM> are additionally releasably mounted to the mounting plate <NUM> so that they can be removed/replaced independently of each other. For example, in some embodiments, several pump modules <NUM> are attached to a common mounting plate <NUM> by individual mounting portions <NUM>, in the same way that the pump modules <NUM> of the embodiment of <FIG> above are attached to an upper surface of the housing <NUM>.

As best illustrated in <FIG> and <FIG>, the mounting plate <NUM> extends beyond the area defined by the open end of the housing <NUM> (e.g. behind the housing <NUM>). In this way, the mounting plate <NUM> provides a shoulder <NUM> which can be used to mount the hydraulic pump system <NUM> to a vehicle. The portion of the mounting plate <NUM> which extends beyond the area defined by the open end of the housing <NUM> also provides space for mounting additional components such as electronics, filters or the like.

In the embodiment of <FIG>, a cover <NUM> is provided for the components which are external to the tank <NUM> (i.e. electric motors <NUM>, inverters <NUM> and other electronics). The cover <NUM> protects such components from impact, dirt and debris, and also reduces the transmission of noise generated by these components, which results in a quieter pump system <NUM>.

Although not illustrated, it will be understood that the cover <NUM> would include one or more suitable apertures, cutaways or the like for access to the hydraulic ports <NUM> (e.g. to connect hoses thereto).

In some embodiments, the cover <NUM> includes sound-absorbing material (e.g. lined on an inside of the cover <NUM>).

The cover <NUM> can be formed of plastics material, metallic material (e.g. steel or aluminium) or any other suitable material.

As illustrated in <FIG>, the mounting plate <NUM> includes a slot <NUM> for allowing airflow inside the cover <NUM> (e.g. for cooling the electronic components located therein). In alternative embodiments, such a slot <NUM> is provided in the cover <NUM>, or a plurality of such slots <NUM> are provided in the mounting plate <NUM> and/or cover <NUM>.

Referring now to <FIG>, a working vehicle according to an embodiment is indicated at <NUM>. The working vehicle <NUM> includes a working arm <NUM> controlled by a plurality of hydraulic actuators <NUM>. The working vehicle <NUM> also includes a pair of left and right tracks <NUM> for moving the working vehicle <NUM>. The left and right tracks <NUM> are driven by respective hydraulic motors. A set of user inputs <NUM> (e.g. joy-sticks, levers, buttons, pedals etc.) are provided on the working vehicle <NUM> for controlling movement of the working vehicle <NUM> and the working arm <NUM>.

The working vehicle <NUM> also includes a hydraulic pump system <NUM> as described above in relation to <FIG> or a hydraulic pump system <NUM> as described above in relation to <FIG>. The hydraulic pump system <NUM>, <NUM> is provided to supply hydraulic fluid <NUM> to the hydraulic actuators <NUM> and left/right track motors of the working vehicle <NUM>. As has been outlined above, the hydraulic pump systems <NUM>, <NUM> of <FIG> and <FIG> are particularly compact and efficient. This provides significant benefits when applied to a working vehicle <NUM> (where space is restricted and power is of limited capacity), particularly when the working vehicle <NUM> is an electric working vehicle where increased efficiency results in increased battery life and periods of use between charging, or a fuel cell powered working vehicle where reduced energy losses result in reduced fuel consumption.

In the illustrated embodiment, the working vehicle <NUM> is of the type known as an excavator. In alternative embodiments, the working vehicle is a different type of vehicle. For example, in some embodiments the working vehicle is a backhoe loader, telehandler, skid-steer loader, dumper, forklift truck or other type of working vehicle having one or more hydraulically-actuated devices.

In alternative embodiments, the hydraulic pump system <NUM>, <NUM> is part of a hydraulic system of a static application rather than a mobile application such as a working vehicle (e.g. the hydraulic pump system <NUM>, <NUM> is part of an industrial hydraulic system in a manufacturing or processing plant).

The term "module" used throughout this description is to be interpreted as an attachable/detachable self-contained unit comprising components that can be installed in or removed from the hydraulic pump system <NUM> as a single unit, i.e. without having to connect/disconnect interconnected components of the module to or from one another.

Although the disclosure has been described in relation to one or more embodiments, it will be appreciated that various changes or modifications can be made without departing from the scope defined by the appended claims. For example:.

Claim 1:
A hydraulic pump system comprising:
a housing (<NUM>) defining a tank (<NUM>) for containing hydraulic fluid in use;
one or more pump modules (<NUM>) each comprising a hydraulic pump for supplying hydraulic fluid from the tank to a hydraulic system; and
a mounting arrangement (<NUM>);
wherein the or each pump module is mounted to the housing by the mounting arrangement,
wherein the or each hydraulic pump comprises a body (<NUM>), and wherein the body extends at least partially into the tank, and
wherein the housing comprises an outer casing, and characterised in that the hosing further comprises an inner liner (212b) spaced apart from the outer casing to define a cavity therebetween.