WO2003062600A1 - Mecanisme de verrouillage temporaire pour pompe hydraulique a pistons axiaux - Google Patents

Mecanisme de verrouillage temporaire pour pompe hydraulique a pistons axiaux Download PDF

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Publication number
WO2003062600A1
WO2003062600A1 PCT/AU2003/000040 AU0300040W WO03062600A1 WO 2003062600 A1 WO2003062600 A1 WO 2003062600A1 AU 0300040 W AU0300040 W AU 0300040W WO 03062600 A1 WO03062600 A1 WO 03062600A1
Authority
WO
WIPO (PCT)
Prior art keywords
pump
motor assembly
cylinder block
cylinder
assembly according
Prior art date
Application number
PCT/AU2003/000040
Other languages
English (en)
Inventor
Allan Rush
Original Assignee
Permo-Drive Research And Development Pty Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AUPS0032A external-priority patent/AUPS003202A0/en
Priority claimed from AUPS0031A external-priority patent/AUPS003102A0/en
Priority claimed from AUPS0030A external-priority patent/AUPS003002A0/en
Application filed by Permo-Drive Research And Development Pty Ltd filed Critical Permo-Drive Research And Development Pty Ltd
Publication of WO2003062600A1 publication Critical patent/WO2003062600A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K6/00—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units
    • B60K6/08—Prime-movers comprising combustion engines and mechanical or fluid energy storing means
    • B60K6/12—Prime-movers comprising combustion engines and mechanical or fluid energy storing means by means of a chargeable fluidic accumulator
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03C—POSITIVE-DISPLACEMENT ENGINES DRIVEN BY LIQUIDS
    • F03C1/00—Reciprocating-piston liquid engines
    • F03C1/02—Reciprocating-piston liquid engines with multiple-cylinders, characterised by the number or arrangement of cylinders
    • F03C1/06—Reciprocating-piston liquid engines with multiple-cylinders, characterised by the number or arrangement of cylinders with cylinder axes generally coaxial with, or parallel or inclined to, main shaft axis
    • F03C1/0602—Component parts, details
    • F03C1/0607—Driven means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03C—POSITIVE-DISPLACEMENT ENGINES DRIVEN BY LIQUIDS
    • F03C1/00—Reciprocating-piston liquid engines
    • F03C1/02—Reciprocating-piston liquid engines with multiple-cylinders, characterised by the number or arrangement of cylinders
    • F03C1/06—Reciprocating-piston liquid engines with multiple-cylinders, characterised by the number or arrangement of cylinders with cylinder axes generally coaxial with, or parallel or inclined to, main shaft axis
    • F03C1/0636—Reciprocating-piston liquid engines with multiple-cylinders, characterised by the number or arrangement of cylinders with cylinder axes generally coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block
    • F03C1/0644—Component parts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
    • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F04B1/128—Driving means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
    • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F04B1/20—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block
    • F04B1/2007—Arrangements for pressing the cylinder barrel against the valve plate, e.g. by fluid pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
    • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F04B1/20—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block
    • F04B1/2014—Details or component parts
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/62—Hybrid vehicles

Definitions

  • the present invention relates generally to hydraulic motors and pumps, and more particularly to positive displacement axial piston motors and pumps.
  • the invention has been developed primarily for use with a pump/motor assembly which forms part of a regenerative drive system ("RDS"), and will be described predominantly hereinafter in that context. It should be appreciated, however, that the invention is not limited to this particular field of use, being readily adaptable to any axial piston hydraulic motor or pump for use in virtually any application.
  • RDS regenerative drive system
  • the RDS is based upon a positive displacement pump/motor arrangement incorporating a cylinder block which houses a cylindrical array of axially reciprocating pistons.
  • the cylinder block and valve face are coaxially disposed around the primary drive shaft, thereby avoiding the need for intermediate gearing, chains, belts or other transmission elements.
  • the resultant regenerative drive system provides a practical and commercially viable system for harnessing the previously wasted braking energy of a vehicle, storing this energy, and subsequently releasing it back into the drive train as required under conditions of acceleration, load, or gear change transitions.
  • This RDS arrangement significantly improves the overall efficiency of the engine and power transmission systems of the vehicle.
  • the RDS system also conveniently acts as an efficient auxiliary braking mechanism in the energy accumulation mode.
  • the system as described is subject to several significant limitations, many of which are common to previously known axial piston hydraulic motors and pumps.
  • one significant limitation in the pump/motor assembly as previously described relates to the inherent drag associated with the seals, bearings, valve faces and other elements that are in direct sliding contact with each other, as the cylinder block and other components in the rotational group rotate with respect to the valve plate, housing and other stationary components of die system, i the particular RDS unit described, these factional drag forces are reduced by virtue of the fact that most of the components in direct contact with one another "float" on a film of oil, which is often pressurised. Nevertheless, a residual drag factor remains, which consumes power, generates heat, and compromises the potential efficiency of the system.
  • the present invention is concerned more specifically with the drag normally attributable to the direct communication between the rotational group including the cylinder block, and the valve plate, i the pump/motor assembly and RDS unit as previously described in the earlier patent application referenced above, a "hold-down" spring is disposed resiliently to bias the cylinder block axially into face-to-face sliding engagement with the valve plate. Because of the relatively high pressures generated within the pump/motor assembly, the hold-down spring is required to exert a relatively high degree of axial force on the cylinder block in order to prevent excessive fluid leakage between the block and the valve plate.
  • the relatively high axial force between the cylinder block and the valve plate causes significant frictional drag between these components as they slide rotationally relative to one another, separated only by a thin film of pressurised oil.
  • the associated inefficiency is particularly significant in situations where the pump/motor assembly is operating in a neutral or "free-wheel" mode, in which the unit is neither pumping nor driving but is nevertheless rotating, often at high speed, as a result of direct connection with a rotary source of power or load.
  • the basic problem is compounded in such conditions because the drag factor itself is exacerbated when the pump/motor unit is operating in the neutral or free-wheeling mode. This is because the unit is not producing hydraulic pumping pressure sufficient to sustain the film of hydrostatic pressurised oil required to minimise the effect of fiictional drag between the components in direct rotational contact with one another.
  • the invention provides a positive displacement hydraulic pump/motor assembly including:- a rotary cylinder block having a central axis and incorporating a generally circular array of cylinders disposed in parallel relationship around the axis; a corresponding plurality of axial pistons reciprocably disposed within the respective cylinders; drive means to effect rotation of the cylinder block about the central axis; a drive plate disposed at one end of the cylinder block to effect sequentially staggered reciprocation of the pistons in response to rotation of the cylinder block; a stationary valve plate disposed at an opposite end of the cylinder block, the valve plate having a valve face adapted for sliding rotational engagement with a complementary mating face formed on the cylinder block; the valve plate further including at least one inlet port adapted for fluid communication with a source of hydraulic fluid and at least one outlet port adapted for fluid
  • the drive means include a drive shaft, disposed in coaxial relationship with the cylinder block. Most preferably, the drive shaft extends through a complementary bore formed in the cylinder block.
  • the assembly preferably further includes coupling means disposed drivingly to connect the shaft to the cylinder block.
  • the coupling means may be fixed or selectively releasable.
  • the shaft is splined or keyed to the cylinder block within the bore.
  • the positive displacement pump/motor is a swash plate type unit
  • the drive plate takes the form of a stationary swash plate, which is inclined with respect to the central rotational axis of the cylinder block.
  • the ends of the pistons remote from the valve plate include “followers” adapted to slide over the swash plate as the cylinder block rotates.
  • a hold-down plate is preferably disposed to capture the floating ends of the pistons and retain the followers in sliding contact with the swash plate, hi alternative embodiment, however, springs or other suitable means may be used to retain the followers in contact with the swash plate.
  • the angle of inclination of the swash plate is selectively adjustable, to provide variable flow rate characteristics.
  • the swash plate is preferably adapted to be selectively inclined in a positive or a negative sense, thereby enabling the assembly alternately to operate as a motor or a pump.
  • the variable swash plate can also be oriented in an intermediate or neutral position, effectively normal to the central axis, such that rotation of the cylinder block causes no movement of the pistons, hence induces no net flow into or out of the cylinders through the ports, and therefore causes no load on the system aside from a residual level of inherent fiictional drag.
  • the invention may also be applied to a bent axis type hydraulic pump, hi that case, connecting rods for the pistons are pivotably attached to a thrust plate adapted to rotate with the cylinder block.
  • the invention may also be adaptable to other configurations of motors and pumps.
  • the pump/motor assembly further includes selectively variable bias means disposed to apply a variable bias force urging the respective mating faces on the cylinder block and the valve plate into sealing engagement.
  • the bias means include an hydraulic hold-down piston disposed within a complementary hold down cylinder.
  • An electronically activated hydraulic valve actuator is preferably also provided to regulate pressure in the hold-down cylinder.
  • the hold-down cylinder is preferably supplied by pilot pressure from the pump/motor assembly. Alternatively, however, it may be supplied from an external source of hydraulic fluid pressure. It will also be appreciated that the hold-down piston need not be hydraulic, but could alternatively be operated by means of an electromagnetic solenoid, a mechanical screw, or other suitable electrical, magnetic, electro-magnetic, mechanical, hydraulic, pneumatic or hybrid arrangements.
  • the hydraulic hold-down piston takes the form of an annular sleeve disposed coaxially around the drive shaft, at the end of the cylinder block remote from the valve plate.
  • the valve actuator is preferably adapted to supply pressurised oil into the hydraulic hold-down cylinder, and release oil from that cylinder, according to the pressure and flow characteristics of the pump/motor assembly.
  • the system is ideally regulated such that under conditions of minimal motor or pump load, the pressure to the hold-down cylinder is released or substantially reduced so as to minimise fiictional drag between the rotary cylinder block and the stationary valve plate.
  • the supply pressure to the hold-down cylinder is substantially increased, so as to minimise leakage from the ports at the interface between the cylinder block and the valve plate.
  • This pressure regulation may be controlled in a linear, step-wise or other manner in response to pressure changes at selected points in the system.
  • the assembly includes a non-adjustable retention spring disposed to provide a minimum level of substantially constant initial bias force sufficient to hold the cylinder block against the valve plate at a relatively low threshold pressure.
  • the retention spring takes the form of a preloaded annular bevel or frusto-conical washer disposed within an annular recess formed between the hold-down piston and the cylinder block.
  • the threshold force provided by the retention spring is sufficient to allow the pump to supply a predetermined level of pilot pressure to the hydraulic hold- down cylinder with minimal leakage, at an initial positive or negative (but non-zero) swash plate angle.
  • This initial swash plate angle for the desired level of pilot pressure is preferably between 0.1 degrees and around 5.0 degrees, more preferably between 0.3 and around 1.0 degrees, and ideally around 0.5 degrees off the neutral or zero position.
  • the invention preferably further includes a selectively operable hydraulic lift-off cylinder effectively interposed between the cylinder block and the valve plate, such that upon actuation, the cylinder block is axially displaced marginally away from the valve plate.
  • the exposed end of the lift-off cylinder is in direct contact with a thrust bearing, to facilitate continued rotation of the cylinder block with minimal fiictional resistance.
  • the lift-off cylinder would normally only be activated with the swash plate in the neutral position, when there is minimal internal pressure within the pump/motor assembly.
  • the coupling means include a locking mechanism, desirably in the form of a tapered locking collet disposed coaxially around the drive shaft.
  • the locking collet is desirably splined internally for engagement with a correspondingly splined section of the shaft, so as to transmit rotary drive, while accommodating a limited degree of relative axial displacement between the collet and the shaft.
  • the hydraulic hold-down cylinder in addition to its function of applying a variable hold-down force, is configured to positively disengage the locking collet mechanism when the hydraulic lift-off cylinder is simultaneously de-pressurised.
  • the inner surface of the cylinder block is preferably tapered to match the outer surface profile of the locking collet.
  • the outer surface of the locking collet is preferably also splined, for engagement with complementary splines formed on the inner surface of the cylinder block such that upon axial engagement, the two components become mechanically interlocked for conjoined rotation. In this way, the locking collet positively transmits rotary drive from the shaft to the cylinder block, while still allowing a limited degree of axial displacement of the rotational group along the shaft.
  • This limited degree of axial displacement, with the splines engaged, preferably permits the cylinder block to be alternately held positively against the valve plate by the hold-down cylinder and displaced marginally away from the valve plate by the lift-off cylinder.
  • the shaft is able to spin independently of the surrounding rotational group.
  • this mechamsm selectively allows fiictional and hydrodynamic drag to be further reduced in situations where the pump/motor assembly is not under load.
  • interlocking engagement may be used as an alternative to splines, to selectively transmit drive between the shaft and the cylinder block.
  • outer surface of the locking collet may not be splined or otherwise mechanically keyed for interlocking engagement with the mating inner surface of the surrounding cylinder block. Rather, the locking mechanism may rely upon progressive, albeit less positive, fiictional engagement.
  • the invention is adapted for incorporation into an energy management system operable in a driving mode, a braking mode and a neutral mode
  • the energy management system including:- energy accumulation means operable selectively to store and release energy through controlled receipt and release of hydraulic fluid; a positive displacement hydraulic pump/motor assembly as defined above, in fluid communication with the energy accumulation means; an hydraulic reservoir in fluid communication with the pump/motor assembly; and a drive shaft; the system being arranged such that in the braking mode the pump/motor assembly retards the drive shaft by pumping hydraulic fluid into the accumulation means, in the driving mode the pump/motor assembly supplies supplementary power to the drive shaft using pressurised hydraulic fluid from the accumulation means, and in the neutral mode the pump/motor assembly is effectively inoperative and exerts no substantial driving or retarding influence on the drive shaft.
  • the drive shaft forms part of the drive train of a vehicle.
  • the drive shaft extends through a complementary bore formed in the cylinder block, such that the drive shaft and the cylinder block are coaxial, the pistons of the pump/motor assembly are uniformly disposed in parallel relationship around the drive shaft.
  • the coupling means preferably include a splined connection directly between the vehicle drive shaft and the cylinder block.
  • gears, clutches, or other coupling mechanisms may be interposed to transmit rotary drive between the vehicle drive train and the pump/motor unit.
  • Such transmission may be mechanical, hydraulic, pneumatic or electromagnetic. It may also be permanently engaged or decouplable, manual or automatic, and may include constant or variable reduction ratios.
  • the pump/motor assembly includes at least three external ports to permit ingress and egress of hydraulic fluid, with a first port communicating with an inlet of the hydraulic reservoir, a second port communicating with an outlet of the hydraulic reservoir, and a third port communicating with the accumulation means.
  • a heat exchanger is preferably disposed between the first port and the hydraulic fluid reservoir.
  • a plurality of positive displacement axial piston pumps is arranged axially along the drive shaft. These pumps may be connected hydraulically to operate in series, parallel, or a combination of both.
  • the energy management system includes a flow control circuit through which hydraulic fluid may be selectively directed, the control circuit being adapted to provide a controllable resistance enabling the pump/motor unit selectively to exert a retarding force on the drive shaft when required, even if the accumulation means are fully charged.
  • the accumulation means include a gas/liquid accumulator comprising a double-ended cylinder and a piston adapted to float sealingly within the cylinder.
  • One side of the cylinder preferably contains a compressible inert gas such as nitrogen, while the other side of the cylinder is preferably connected hydraulically to the pump/motor unit.
  • the accumulator is preferably thereby adapted to store energy by pumping hydraulic fluid into one side of the cylinder, so as to compress the gas on the other side by displacement of the floating piston, and subsequently to release that energy by expulsion of hydraulic fluid as the compressed gas expands, hi alternative embodiments, however, other forms of accumulator, such as bladder or diaphragm type accumulators, may be readily substituted.
  • the assembly preferably includes a plurality of accumulators, which may be selectively connected in series, parallel or a combination of both, as required.
  • figure 1 is a cross-sectional view of a pump/motor assembly, showing a hold- down cylinder activated in the normal operating or loaded configuration, according to a first embodiment of the invention
  • figure 2 is a cross-sectional view similar to figure 1, showing the hold-down cylinder in the unloaded or deactivated configuration
  • figure 3 is a cross-sectional view showing a pump/motor assembly incorporating a lift-off cylinder shown in the normal operating (deactivated) mode, according to a second embodiment of the invention (NB -
  • this version of the pump/motor unit as illustrated substitutes a conventional spring for the hold-down cylinder shown in figures 1 and 2
  • figure 4 is a cross-sectional view of the pump/motor unit of figure 3, showing the lift-off cylinder in the unloaded (activated) mode
  • figure 5 is a cross-sectional view showing a pump/motor assembly incorporating a hold-down cylinder, a lift
  • the invention provides a positive displacement hydraulic pump/motor unit 1.
  • the pump/motor unit includes a stationary housing 2 and a cylinder block 3 supported within the housing for rotation about a central axis 5.
  • the block 3 incorporates a circular array of hydraulic cylinders 6 uniformly disposed in parallel relationship about the central rotational axis 5.
  • a corresponding array of axial pistons 10 is reciprocably disposed within the respective cylinders.
  • a central drive shaft 12 extends through a complementary bore 13 formed in the cylinder block. The shaft is drivingly connected to the cylinder block 3 by coupling means including spline formations 14 to effect rotation of the block about the central axis, as described in more detail below.
  • a stationary drive plate in the form of swash plate 15 is disposed at one end of the cylinder block (the right-hand end when viewing the drawing).
  • the swash plate is pivotably supported within the housing, for adjustable movement within a predetermined range, about an axis substantially normal to the rotational axis of the cylinder block.
  • a hold-down plate 16 is disposed to locate the free ends of the pistons remote from the valve plate in the appropriate relative spatial relationship, while the end faces of the pistons are formed with followers 18 adapted to engage and slidably traverse the operative surface of the swash plate. In this way, rotation of the cylinder block effects sequentially staggered reciprocation of the pistons, with the amplitude of piston travel being determined by the selected angle of inclination of the swash plate.
  • a stationary valve plate 20 is disposed at the opposite end of the cylinder block (the left-hand end when viewing the drawings) and is rigidly connected to the housing.
  • the valve plate includes a valve face 21 adapted for sliding rotational engagement with a complementary mating valve face 22 formed on the abutting end of the cylinder block.
  • the valve plate includes inlet ports 24 adapted for communication with a source of hydraulic fluid, and outlet ports 26 adapted for fluid communication with an hydraulic load.
  • the valving is arranged such that hydraulic fluid is progressively drawn into the cylinders in sequence through the inlet ports as the pistons withdraw away from the valve plate and is subsequently expelled from the cylinders through the outlet ports as the respective pistons are progressively advanced toward the valve plate, under the influence of the swash plate.
  • the swash plate is pivotably supported within the housing such that the effective angle of inclination with respect to the rotational axis of the cylinder block is adjustable to provide selectively variable flow characteristics, hi particular, the swash plate may be alternately inclined in a positive and a negative sense, thereby enabling the assembly selectively to operate as a motor or a pump, hi this regard, it should be appreciated that the particular valve ports which function as inlets to the cylinders of the pump/motor unit, and those which function as outlets, will alternate according to the operational mode of the unit.
  • the swash plate can also be orientated in an intermediate or neutral position in a plane effectively normal to the central axis, such that rotation of the cylinder block produces no reciprocation of the pistons. In this mode, the pump/motor unit induces no net fluid flow into or out of the cylinders, and consequently transfers no significant hydraulic load to the shaft.
  • the version of the pump/motor unit as illustrated further includes controllable bias means disposed to apply a variable bias force urging the mating faces 21 and 22 on the valve plate and the cylinder block respectively into sealing engagement.
  • the bias means include an hydraulic hold-down piston 30 disposed within a complementary hold-down cylinder 32.
  • the hold- down piston 30 takes the form of an annular sleeve disposed coaxially around the drive shaft, at the front (right-hand when viewing the drawings) end of the cylinder block, remote from the valve plate.
  • the hold-down cylinder is correspondingly shaped, and is pressurised via a supply passage 35, which extends through the housing and the drive shaft as shown.
  • the pressure supplied to the hold-down cylinder is regulated by an electronic valve actuator 36 (represented diagrammatically in figure 1 only) according to predetermined operational parameters related to the pressure and flow characteristics of the pump/motor assembly and other characteristics of the system, which will vary according to the application.
  • the hold-down cylinder is regulated such that under conditions of relatively high motor or pump load, the supply pressure to the hold- down cylinder is maintained at a predetermined level, sufficient to minimise leakage from the ports between the mating valve faces at relatively high pump/motor pressures. This is the normal operating mode for the unit, as shown in figure 1. Conversely, under conditions of minimal motor or pump load, the pressure to the hold-down cylinder is released or substantially reduced, so as to minimise fiictional /062600
  • valve actuator 36 in a linear, stepwise or other manner in response to pressure changes at selected points in the system. It may also be regulated wholly or in part according to other parameters such as measured leakage flow, fiictional drag, temperature changes or the like, as well as various combinations of such parameters on the basis of a suitable control system.
  • the pump/motor unit ideally includes a non-adjustable retention spring mechanism, with a relatively low level of substantially constant preload, calibrated to provide a minimal threshold level of initial bias force.
  • the retention mechanism takes the form of a preloaded annular bevel or frusto-conical spring washer 39 disposed within a complementary annular recess 40 formed between the hold-down piston and the cylinder block.
  • the bevel spring washer 39 is shown in a flattened configuration in figure 1, corresponding to the normal operational or loaded mode, and in a marginally expanded configuration in figure 2, corresponding to the unloaded or passively released operational mode.
  • the initial bias force of the spring washer 39 is calibrated to hold the cylinder block against the valve plate with a relatively low level of force in the unloaded or released mode of the hold-down cylinder, sufficient simply to allow the pump to begin supplying pilot pressure to the hold-down cylinder via passage 35 at an initial positive or negative (but non-zero) swash plate angle.
  • This initial swash plate angle corresponding to the desired level of pilot pressure is preferably between 0.1 and around 5.0 degrees, more preferably between 0.3 and around 1.0 degrees, and ideally around 0.5 degrees off the neutral or zero position.
  • a second embodiment of the invention additionally includes a selectively operable active release or lift-off mechanism in the form of an hydraulic lift-off piston 40, slidably disposed within an associated lift-off cylinder 41.
  • the lift-off piston and cylinder are again annular in configuration, and positioned coaxially around the central drive shaft.
  • This hydraulic lift-off mechanism is intended primarily to complement the operation of the hold-down cylinder 32 and the associated retention spring 39 mechanism as illustrated in the first embodiment of the invention shown in figures 1 and 2.
  • the lift-off mechanism is shown in figures 3 and 4 in conjunction with a conventional spring- based hold-down mechanism 42 (to which the lift-off mechanism is equally applicable).
  • the lift-off piston and cylinder are effectively interposed between the cylinder block and the valve plate.
  • the liftoff cylinder is depressurised through supply passage 44, and has no effect on the operation of the pump/motor unit.
  • the lift-off cylinder is pressurised again through supply passage 44, whereby the cylinder block is axially displaced away from the valve plate. This is the positively unloaded or actively released mode of operation, as represented in figure 4.
  • the pressure generated within the lift-off cylinder in order to effect positive release of the cylinder block, must be sufficient at least substantially to overcome the threshold bias force of the retention spring 38 or 42 associated with the relevant hold-down mechanism. It will also be appreciated that in the situation where the lift-off cylinder is activated without the inclusion of a hold- down cylinder which may be simultaneously depressurised, the lift-off cylinder must activate against a thrust bearing to allow for the continued rotation of the cylinder block with the shaft.
  • the extent of axial displacement may be marginal, and indeed may even be visually indiscernible.
  • the axial lift-off mechanism enables selective minimisation of fiictional drag between the cylinder block and the valve plate in situations where the pump/motor unit is doing no work.
  • the lift-off cylinder would normally only be activated with the swash plate in the neutral position, when there is consequently minimal internal pressure within the pump/motor assembly. Otherwise, the axial displacement of the cylinder block away from the valve plate, albeit by only a small amount, may result in excessive leakage of pressurised hydraulic fluid past the valve ports.
  • FIG. 5 A further embodiment of the invention is illustrated in figures 5 and 6 where again similar features are denoted by corresponding reference numerals.
  • cylinders 32 and 41 are incorporated into the pump/motor unit.
  • the coupling means additionally include a releasable locking mechanism 50, to enable selective disengagement of the cylinder block and the associated components in the rotational group, from the central drive shaft.
  • this selectively releasable locking mechanism is omitted from the earlier embodiments as illustrated, to facilitate the initial explanation of the surrounding components in the assembly and the supplementary aspects of the invention.
  • the supplementary and primary aspects are integrated together because the resultant mechanical interaction gives rise to significant synergies.
  • the locking mechanism may be implemented in various forms independently, as well as in conjunction with one or both of, the ancillary hold-down and lift-off mechanisms.
  • the locking mechanism 50 as illustrated includes a tapered locking collet 52, which is splined internally for engagement with the corresponding spline formations 14 on the drive shaft.
  • the splined connection transmits rotary drive while accommodating a limited degree of relative axial displacement between the locking collet 52 and the shaft.
  • the inner surface 54 of the cylinder block is shaped to match the tapered external surface profile of the locking collet and these tapered surfaces also incorporate complementary axially interengageable spline formations 55.
  • annular sleeve 60 incorporating a shoulder flange 62 is interposed between the hold-down piston 30 and the locking collet 52
  • the cylinder 41 in the normal operating (locked) mode as shown in figure 5, the cylinder 41 is pressurised via passage 44, which urges that piston to the right (when viewing the drawings) while simultaneously urging the cylinder block to the left, toward the valve plate.
  • the piston 40 advances it drives the locking collet 52, the annular sleeve 60 and the piston 30 axially and in unison to the right, away from the valve plate.
  • cylinder 32 is simultaneously depressurised via passage 35.
  • the cylinder 41 is vented via passage 44 while the cylinder 32 is simultaneously pressurised via passage 35, as shown in figure 6.
  • the end face and 66 of the annular sleeve 60 engages the adjacent face of the locking collet, and drives the locking collet axially toward the valve plate 20 (to the left when reviewing the drawings).
  • the locking collet carries the cylinder block with it. However, once the cylinder block firmly engages the valve plate, no further axial displacement is possible. Upon further pressurisation of cylinder 32, the piston 30, sleeve 60, and collet 52 are displaced progressively toward the valve plate while the cylinder block is held back, until the piston 40 reaches the end of its travel, at which point no further axial displacement of the locking collet is possible. At this point, the previously intermeshing tapered splines 55 on the locking collet and the surrounding cylinder block are disengaged, to permit relative rotation between the rotational group and the drive shaft, i this position, the cylinder block is both unloaded and unlocked, as represented by the configuration shown in figure 6.
  • coil springs 68 are incorporated within the cylinders to bias the respective pistons into contact with the swash plate, thereby minimising free play and noise within the pump/motor unit, particularly when operating in the unloaded or unlocked mode. It will be appreciated that this mechanism, when unlocked in situations where the pump/motor assembly is not under load, effectively eliminates fiictional drag between the cylinder block and the valve plate. It also eliminates drag between the cylinder block and other stationary elements within the housing. This feature is particularly advantageous in applications where the cylinder block rotates within an oil bath and consequently, the hydrodynamic drag on the rotational group is relatively high.
  • the hydraulic pump/motor assembly 1 forms part of an energy management system 72, wherein the drive shaft 12 of the pump/motor unit is connected to the drive line or power train 74 of the vehicle via yokes 76 and 78. In situ, these yokes form parts of universal joints at the respective ends of the drive shaft. In this way, the drive shaft of the pump/motor unit becomes serially connected with, and an integral part of, the drive line of the vehicle, thereby obviating the need for gearboxes, chain drives, belt drives, or other intermediate transmission mechanisms. This makes the unit efficient, compact, reliable, and readily retrofitable to existing vehicles.
  • the system further includes energy accumulation means in the form of a pair of gas/liquid accumulators 80, each comprising a double- ended cylinder 82 and a piston (not shown) adapted sealingly to float within the cylinder.
  • One side of each cylinder contains a compressible inert gas such as nitrogen, while the other side of the cylinder is in fluid communication with the pump/motor unit via hydraulic lines.
  • Each accumulator is thereby adapted to store energy by receiving pressurised hydraulic fluid into one side of the cylinder so as to compress the gas on the other side, and adapted subsequently to release that energy by expulsion of the hydraulic fluid as the compressed gas is allowed to expand.
  • the system is selectively operable in any one of three primary modes.
  • a first braking mode the system operates to retard the drive shaft of the vehicle by pumping hydraulic fluid into the accumulators and thereby compressing the contained gas medium.
  • the system is operable in a driving mode to supply supplementary power to the drive shaft of the vehicle using the pressurised hydraulic fluid from the accumulators.
  • the hydraulic pump/motor unit operates as a pump powered by the vehicle drive shaft, whereas in the driving mode, the unit operates as a motor powered by pressurised hydraulic fluid from the accumulators.
  • the system is also operable in a third neutral or "free wheeling" mode, whereby the drive shaft of the vehicle is substantially unaffected by the pump/motor unit, aside from any residual fiictional drag which the present invention aims to minimise.
  • the cylinder block In the neutral or free wheeling mode, the cylinder block may be marginally displaced from the valve plate by selective actuation of the lift-off cylinder, to minimise a key source of fiictional power loss within the pump/motor unit.
  • the locking collet Simultaneously or alternatively, the locking collet may be selectively disengaged. As previously described, this avoids the need for the cylinder block to rotate in unison with the drive shaft when not required. The effect of this disengagement is to substantially eliminate a primary source of hydrodynamic drag which arises by virtue of the fact that the rotational group normally spins in an oil bath contained within the housing.
  • the three primary operational modes are controlled by the angle of inclination of the swash plate 15, in the manner previously described.
  • the RDS management system is programmably responsive to a predetermined series of system parameters such as accelerator, brake and clutch pedal positions, engine speed, gear selection, engine manifold pressure, swash plate position, drive line torque, accumulator pressure and hydraulic pump/motor pressure.
  • the system may also be pre-programmed with topographical mapping and terrain data, thereby enabling it effectively to anticipate inclines and declines as well as stopping and acceleration points on known routes, and optimise the performance of the RDS on that basis. Again, the general operating principles in this respect are described in more detail in PCT/AU99/00740.
  • the RDS unit as illustrated is positioned in the central drive line of the vehicle, immediately downstream of the engine 92 and gearbox 94. This is advantageous, because in that position, the system can be readily retrofitted to existing vehicles by replacement of a standard section of the original drive line. It should be understood, however, that the unit may alternatively be positioned between the engine and gearbox, for example in direct connection with the crank shaft. As another alternative, it may be incorporated into a gearbox or engine casing. It may also be positioned downstream of one or both of the differentials 98, and may even be incorporated into an axle. In that case, it will be apparent that several RDS units may be incorporated into multiple drive line sections, axles or stub axles.
  • the pump/motor unit may be required to operate in a neutral or freewheeling mode for prolonged periods, and any residual fiictional drag during such periods can impact materially on the overall efficiency of the system.
  • the invention represents both a practical and a commercially significant improvement over the prior art.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Transportation (AREA)
  • Reciprocating Pumps (AREA)
  • Hydraulic Motors (AREA)

Abstract

L'invention concerne un ensemble moteur/pompe hydraulique à déplacement positif pour un système de gestion d'énergie pouvant fonctionner en mode d'entraînement, en mode de freinage et en mode neutre afin de fournir un entraînement supplémentaire à partir d'un freinage de récupération dans un véhicule. L'ensemble décrit dans cette invention comprend un bloc-cylindres rotatif présentant un axe et un réseau généralement circulaire de cylindres et des pistons axiaux. Un arbre d'entraînement entraîne la rotation du bloc-cylindres et un plateau d'entraînement entraîne le mouvement alternatif séquentiel des pistons. Une plaque porte-soupape fixe comprend un collet de soupape conçu pour s'engrener par rotation et par glissement avec une face correspondante complémentaire formée sur le bloc-cylindres et des orifices d'entrée/sortie communiquant avec une source hydraulique et une charge. Le moyen (50) de couplage à séparation sélective est conçu, lorsqu'il est en mode engrené, pour relier l'arbre d'entraînement au bloc-cylindres et, en mode déconnecté, pour désolidariser l'arbre d'entraînement et le bloc-cylindres.
PCT/AU2003/000040 2002-01-18 2003-01-17 Mecanisme de verrouillage temporaire pour pompe hydraulique a pistons axiaux WO2003062600A1 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
AUPS0032A AUPS003202A0 (en) 2002-01-18 2002-01-18 Hold-down cylinder for axial piston hydraulic pump
AUPS0031A AUPS003102A0 (en) 2002-01-18 2002-01-18 Releasable locking mechanism for axial piston hydraulic pump
AUPS0032 2002-01-18
AUPS0030 2002-01-18
AUPS0031 2002-01-18
AUPS0030A AUPS003002A0 (en) 2002-01-18 2002-01-18 Lift-off cylinder for axial piston hydraulic pump

Publications (1)

Publication Number Publication Date
WO2003062600A1 true WO2003062600A1 (fr) 2003-07-31

Family

ID=27616945

Family Applications (3)

Application Number Title Priority Date Filing Date
PCT/AU2003/000042 WO2003062602A1 (fr) 2002-01-18 2003-01-17 Cylindre de retenue pour pompe hydraulique a piston axial
PCT/AU2003/000041 WO2003062601A1 (fr) 2002-01-18 2003-01-17 Cylindre de relevage pour pompe hydraulique a pistons axiaux
PCT/AU2003/000040 WO2003062600A1 (fr) 2002-01-18 2003-01-17 Mecanisme de verrouillage temporaire pour pompe hydraulique a pistons axiaux

Family Applications Before (2)

Application Number Title Priority Date Filing Date
PCT/AU2003/000042 WO2003062602A1 (fr) 2002-01-18 2003-01-17 Cylindre de retenue pour pompe hydraulique a piston axial
PCT/AU2003/000041 WO2003062601A1 (fr) 2002-01-18 2003-01-17 Cylindre de relevage pour pompe hydraulique a pistons axiaux

Country Status (2)

Country Link
US (3) US20030180158A1 (fr)
WO (3) WO2003062602A1 (fr)

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US7909584B2 (en) * 2004-01-30 2011-03-22 Black & Decker Inc. Air compressor
DE102006055800A1 (de) * 2006-11-27 2008-05-29 Robert Bosch Gmbh Hybridantrieb mit Ventilabschaltung
ATE541735T1 (de) * 2007-11-01 2012-02-15 Ducere Holdings Pty Ltd Antriebsanordnung mit als pumpe oder motor betreibbarem hydraulikmechanismus mit offenem regelkreis
CN102725619B (zh) * 2009-06-11 2015-06-24 伊顿公司 混合动力驱动系统中的故障检测和减轻
US8596404B1 (en) * 2010-12-22 2013-12-03 Eaton Corporation Commissioning a hybrid drive assembly of a vehicle
DE102012214807A1 (de) 2012-08-21 2014-05-28 Robert Bosch Gmbh Hydrostatische Verdrängereinheit
US9873325B1 (en) 2014-10-22 2018-01-23 Hydro-Gear Limited Partnership Drive apparatus
JP6612610B2 (ja) * 2015-12-17 2019-11-27 ナブテスコ株式会社 流体圧ポンプおよび流体圧システム
CN111059015B (zh) * 2020-02-10 2024-06-07 元工能源科技集团有限公司 复合结构泵
CN112209210A (zh) * 2020-10-21 2021-01-12 天津市航昊机电设备有限公司 一种扶梯齿轮机构控制装置的供油机构

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US4579043A (en) * 1983-10-25 1986-04-01 Mannesmann Rexroth Gmbh Hydrostatic machine with fixed or variable displacement
US4993780A (en) * 1988-10-24 1991-02-19 Isuzu Motors Limited Regenerative braking system for car
JPH09228948A (ja) * 1996-02-20 1997-09-02 Calsonic Corp 固定容量の斜板式コンプレッサ
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DATABASE WPI Derwent World Patents Index; Class Q12, AN 1997-487615/45 *

Also Published As

Publication number Publication date
US20030180158A1 (en) 2003-09-25
US20030180157A1 (en) 2003-09-25
WO2003062602A1 (fr) 2003-07-31
WO2003062601A1 (fr) 2003-07-31
US20040001763A1 (en) 2004-01-01

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