EP2211058A1 - Hydraulikpumpe - Google Patents

Hydraulikpumpe Download PDF

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Publication number
EP2211058A1
EP2211058A1 EP09001065A EP09001065A EP2211058A1 EP 2211058 A1 EP2211058 A1 EP 2211058A1 EP 09001065 A EP09001065 A EP 09001065A EP 09001065 A EP09001065 A EP 09001065A EP 2211058 A1 EP2211058 A1 EP 2211058A1
Authority
EP
European Patent Office
Prior art keywords
fluid
working machine
cyclically changing
valve
actuated
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP09001065A
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English (en)
French (fr)
Inventor
Michael Richard Dr. Fielding
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Danfoss Power Solutions ApS
Artemis Intelligent Power Ltd
Original Assignee
Sauer Danfoss ApS
Artemis Intelligent Power 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
Application filed by Sauer Danfoss ApS, Artemis Intelligent Power Ltd filed Critical Sauer Danfoss ApS
Priority to EP09001065A priority Critical patent/EP2211058A1/de
Publication of EP2211058A1 publication Critical patent/EP2211058A1/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
    • F04B1/053—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement with actuating or actuated elements at the inner ends of the cylinders
    • F04B1/0535—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement with actuating or actuated elements at the inner ends of the cylinders the piston-driving cams being provided with inlets and outlets
    • 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
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/22—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00 by means of valves
    • F04B49/24—Bypassing
    • 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
    • F04B7/00—Piston machines or pumps characterised by having positively-driven valving
    • F04B7/0076—Piston machines or pumps characterised by having positively-driven valving the members being actuated by electro-magnetic means

Definitions

  • the invention relates to a fluid working machine, comprising at least one fluid inlet port, at least one fluid outlet port and a plurality of cyclically changing cavities, wherein said fluid working machine is able to supply a fluid flow rate sufficient for hydraulic applications and/or wherein said fluid working machine can be supplied by a fluid flow rate, sufficient to propel said fluid working machine.
  • the invention also relates to a method of operating a fluid working machine, comprising at least one fluid inlet port, at least one fluid outlet port and a plurality of cyclically changing cavities, wherein said fluid working machine is able to supply a fluid flow rate sufficient for hydraulic applications and/or wherein said fluid working machine can be supplied by a fluid flow rate, sufficient to propel said fluid working machine.
  • fluid pumps When the pressure level of a fluid has to be increased, fluid pumps are used. Over the years, different types of pumps have been developed. For example, scroll pumps, piston and cylinder pumps, centrifugal pumps, radial blower type pumps, axial blower type pumps, rotary vane pumps or gear pumps are used.
  • the type of pump which is chosen generally depends on the plurality of parameters. For example, the compression ratio, the fluid flow rate to be pumped, the kind of fluid to be pumped or the like can influence the decision on which type of pump to choose.
  • a piston In hydraulic pumps of the piston and cylinder type, a piston is moving back and forth in a cylindrical cavity. By the movement of the piston the volume of the cavity is cyclically changing. When the cavity's volume is expanding, hydraulic fluid is sucked in from the low pressure fluid reservoir. Once the piston has reached its bottom dead center, the cavity's volume starts to contract. During this contraction phase, the hydraulic fluid is expelled out of the pump's cavity towards a high pressure fluid manifold.
  • simple passive valves like check valves can be used.
  • a crankshaft or a cam which is eccentrically mounted on a rotating shaft can be used.
  • a crankshaft or a cam which is eccentrically mounted on a rotating shaft.
  • the fluid output behavior of a multiple cylinder pump can be more homogeneous as compared to a single cylinder pump.
  • Synthetically commutated hydraulic pumps are a unique subset of variable displacement pumps. They are also known under the name digital displacement pump.
  • the fluid inlet valve of the pumping cavity is replaced by an actively actuated valve.
  • the actuation pattern of the actuated valve can be controlled by an electronic controlling unit. If the actuated valve is opened as soon as the piston has reached its top dead center (TDC) (or a short time afterwards) and remains open during the expansion phase of the pumping cavity until the piston has reached its bottom dead center (BDC), and the actuated valve will then be closed during the contraction phase of the pumping cavity, the synthetically commutated hydraulic pump will act as a standard hydraulic pump, comprising passive valves.
  • Another working mode can be achieved if the actuated valves will be closed at some intermediary position between the bottom dead center and the top dead center of the piston during the contraction phase of the pumping cavity. This way, only part of the cyclically changing volume of the pumping cavity will be used for pumping hydraulic oil towards the high pressure side of the synthetically commutated hydraulic pump.
  • the synthetically commutated hydraulic pump design is described in EP 0 361 927 B1 or US 6,651,545 B2 , for example. These pumps have proven to be superior when it comes to quickly adapting to a rapidly changing fluid flow demand. Due to this ability, they have also proven to be particularly energy efficient. This is because it is no longer necessary to short-circuit pressurized hydraulic fluid to the low pressure fluid reservoir without performing useful work, simply because of the fact that momentarily an excess amount of hydraulic fluid is pumped by the hydraulic pump.
  • the design of synthetically commutated hydraulic pumps necessitates low pressure valves, which can be quickly and precisely switched from an open into a closed state by applying an external actuation signal.
  • actuated valves used for synthetically commutated hydraulic pumps have to have a large cross section for hydraulic fluid to pass through them. These requirements make the design of actuated valves, which can be used for synthetically commutated hydraulic pumps, quite elaborate and hence expensive. Examples of the quite complex design of actuated valves which are usable for synthetically commutated hydraulic pumps can be found, for example, in US 2005/006759681 A1 . The comparatively high complexity and the comparatively high price of the actuated valves - and therefore of the resulting synthetically commutated hydraulic machine - has hindered a wide spread application of synthetically commutated hydraulic machines so far.
  • variable displacement high-pressure pump for pumping fluid to an accumulation chamber.
  • the variable displacement high-pressure pump is used as a fuel pump for a common rail fuel injection system.
  • the variable displacement high-pressure pump comprises two pumping units for receiving low-pressure fluid through an inlet and selectively delivering the fluid to the accumulation chamber at a high-pressure.
  • a common fluid passage in fluid communication with the two pumping units is provided. Using the common fluid passage, fluid can be pumped from one of the pumping units to the respective other one of the pumping units.
  • a valve is positioned in the common fluid passage for selectively blocking the flow of fluid between the two pumping units such that the pumping units deliver fluid to the accumulation chamber when the valve blocks the fluid flow between the two pumping units.
  • the high-pressure pump and its components do not have to be designed for high fluid flow rates. Contrary to this, the achievable fluid flow rates have to be much higher for hydraulic fluid working machines (hydraulic pumps and/or hydraulic motors). Therefore, the two technical fields are clearly distinct, due to the totally different fluid flow requirements. Therefore, a person skilled in the technical field of fuel pumps differs from person skilled in the technical field of hydraulic pumps. In particular, the valve in the fluid passage between the two pumping units would have to have completely different fluid flow cross-sections in the aforementioned two technical fields. However, an actuated fluid valve, which shows a high fluid flow cross-section and which can be actuated very fast and precisely at the same time (which would both be required in the technical field of hydraulic fluid working machines), seems to be prohibitively complicated and expensive at first sight.
  • a hydraulic working machine with a plurality of cyclically changing working cavities comprising passive inlet and outlet valves, connecting the working cavities to a low-pressure fluid reservoir and a high-pressure fluid reservoir, respectively.
  • passive inlet and outlet valves connecting the working cavities to a low-pressure fluid reservoir and a high-pressure fluid reservoir, respectively.
  • a cut-off valve between a pair of working cavities Said cut-off valve can be opened at a certain time between the bottom dead centre and the top dead centre of the morning piston of the respective working cavity.
  • the design the necessary cut-off valve is very complicated, because the cut-off valve has to be able to open and close very fast and precisely, has to have a large fluid flow cross-section and has to be able to remain closed under pressure differences, coming from both sides of the cut-off valve.
  • a fluid working machine comprising at least one fluid inlet port, at least one fluid outlet port and a plurality of cyclically changing cavities, wherein said fluid working machine is able to supply a fluid flow rate sufficient for hydraulic applications and/or wherein said fluid working machine can be supplied by a fluid flow rate, sufficient to propel said fluid working machine, wherein at least one passive fluid connecting means is provided in a fluid path, connecting said fluid inlet port and at least one of said cyclically changing cavities in a way that at least one actuated valve, provided in said fluid path, connecting said fluid inlet port and at least one of said cyclically changing cavities, wherein said actuated valve can be actuated on a cycle-by-cycle basis.
  • the fluid path, comprising said passive fluid connecting means and the fluid path, comprising said actuated valve can at least in part fall together and/or can at least in part be different.
  • the fluid path connecting said fluid inlet port and at least one of said cyclically changing cavities can be led through different parts of the fluid working machine.
  • the fluid path can be split up, so that a first part of the fluid path connecting the fluid inlet port and at least one of the cyclically changing cavities is designed as a common fluid path, while a second part of this fluid path is split up, so that two (or even more) separate (fractional) fluid paths are formed.
  • the actuator of the actuated valve can be designed smaller because it has to provide less force for actuating the valve part of said actuated valve.
  • This again can make the design of the actuated valve significantly easier and cheaper.
  • the actuated valve can be actuated on a cycle-by-cycle basis, the pumping performance of the fluid working machine (output fluid flux) can be adapted to a rapidly changing fluid flow demand very fast.
  • the actuated valve has to be designed in a relatively complex way so that it is able to open and close sufficiently fast and sufficiently precise even at high speeds of the fluid working machine (e.g. at high RPMs).
  • the fluid working machine should be able to deliver a fluid flow rate of 1 cm 3 /s, 5 cm 3 /s, 10 cm 3 /s or even more, if the fluid working machine is used as a fluid pump (and/or to be propelled with such a fluid flow rate, if the fluid working machine is used as a hydraulic motor).
  • a fluid flow rate 1 cm 3 /s, 5 cm 3 /s, 10 cm 3 /s or even more
  • the fluid working machine can be used in times with a lower fluid flow rate.
  • different numbers could be used as well, in particular every natural number with the unit cm 3 /s.
  • At least one of said actuated valves of said fluid working machine is arranged in a common fluid path of at least two of said cyclically changing cavities.
  • this embodiment it is possible to significantly reduce the overall cost for the fluid working machine, since generally the overall number of actuated valves can be reduced.
  • a single actuated valve is used for two or even more cyclically changing cavities.
  • one, several and/or all of the connected cyclically changing cavities is (are) able to perform idle strokes, part strokes and/or full strokes.
  • at least part of the cyclically changing cavities can not only be in the same phase of their working cycles, but can also be out of phase from each other, i.e. in different phases of their respective working cycle.
  • the fluid working machine in a way that at least one of said actuated valves and at least one of said passive fluid connecting means are arranged in series and/or in parallel.
  • the overall number of actuated valves within the resulting fluid working machine can be reduced.
  • the design of the actuated valve can be simplified (for example by reducing the fluid flow cross section, thus simplifying the design for the actuator part of the actuated valve and/or reducing the force which has to be produced by the actuator part of the actuated valve).
  • the possible fluid flow rates through the respective valves can add up to a higher overall fluid flux. This can be the case during certain time intervals and/or when considering the mean average over several working cycles of the cyclically changing cavities.
  • one of the valves for example the passive fluid connecting means, can be used to provide a closure of the fluid path even if the other valve (for example the actuated valve) is still in an open position for performing a different task, for example for supplying fluid to another cyclically changing cavity.
  • At least one of said actuated valves and a plurality of said passive fluid connecting means, in particular of passive fluid connecting means which are connecting to different cyclically changing cavities, are connected to at least one common fluid chamber of said fluid working machine.
  • This common fluid chamber can be used for distributing a common fluid path (for example the first section of a fluid path) to a plurality of different fluid paths (e.g. "parallel" fluid paths).
  • the common fluid chamber can be designed as a simple bifurcation or can comprise a certain volume. Using a simple bifurcation, the overall design volume of the fluid working machine can be reduced.
  • the common fluid paths are comprising the actuated valve(s), while the "parallel" fluid paths comprise the passive fluid connecting means.
  • the number of the more expensive actuated valves can be reduced as compared to the overall number of the relatively cheap passive fluid connecting means.
  • the overall cost of the resulting fluid working machine can be reduced. This is usually even the case, if the reduction in the number of actuated valves necessitates an increase in the number of passive fluid connecting means.
  • the fluid working machine is designed in a way that at least one high-pressure valve is provided in a fluid path between at least one of said fluid outlet ports and at least one of said cyclically changing cavities, or in particular between at least one of said fluid outlet ports and at least one of said common fluid chambers.
  • a fluid path can be established towards the high pressure fluid manifold of the fluid working machine (depending on the position of the at least one high-pressure valve).
  • at least one of said high-pressure valves is designed as a passive fluid connecting means, for example a biased-closed check valve. This way costs can be saved and the design of the fluid working machine can be simplified.
  • the common fluid chamber is used as some kind of a "general fluid distributing chamber" which is not only used during the intake stroke, but also during the output stroke of the one or several cyclically changing cavities.
  • the fluid working machine is designed in a way that at least one of said passive fluid connecting means is arranged in a fluid path which is going at least in part through a preferably common driving unit of said plurality of cyclically changing cavities and/or which is at least in part going through a part of at least one of said cyclically changing cavities which is neighboring said preferably common driving unit, or is designed as a passive valve unit, in particular as a poppet valve and/or as a spool valve.
  • the head-part of the piston-and-cylinder arrangement i.e. the part, being on the opposite side of the crankshaft
  • the bottom-part i.e. the part, being in the vicinity of the crankshaft.
  • a fluid flow area can be provided which can even exceed the fluid flow area provided by fluid working machines according to the state of the art. This is done by using areas of the cyclically changing cavities (e.g. in a piston-and-cylinder arrangement) which are so far generally not used. This is even possible without (significantly) increasing dead volumes.
  • the common driving unit can be in particular a common crankshaft, which is present in the radial piston pump or even a so-called "wedding cake"-type pump, for example. In such a common crankshaft an opening like an elongated ditch can be provided.
  • a passive fluid connecting means can show the behavior of a passive and/or of an actuated valve (at least to a certain extent).
  • cyclically changing cavities not only the cavity itself, but also neighboring parts of this cavity are encompassed.
  • the piston-like part is encompassed by this expression.
  • a fluid path leading through a part of at least one of the cyclically changing cavities can be designed as a bore in a piston-like structure of the fluid working machine.
  • a fluid path of the presently suggested type will be arranged in parallel to a fluid path, comprising the "real" actuated valve(s).
  • each cyclically changing cavity may be equipped with at least one (additional) low pressure passive fluid connecting means to admit fluid directly into but not out of the cyclically changing cavity.
  • a low pressure passive fluid connecting means may be a check valve biased to the closed position and oriented so that fluid cannot escape the cyclically changing cavity through it.
  • a low pressure passive fluid connecting means may be an enlongated ditch formed in the crankshaft as described above, the ditch being arranged to let fluid into but not out of the cyclically changing cavity by virtue of its being fluidly connected with the cyclically changing cavity when the cyclically changing cavity is expanding and fluidly disconnected from the cyclically changing cavity when the cyclically changing cavity is contracting.
  • fluid admitted through a low pressure passive fluid connecting means comes directly or indirectly from a reservoir of low pressure fluid brought to the fluid working machine or held within the fluid working machine.
  • a plurality of (additional) low pressure passive fluid connecting means can be provided as well.
  • the (additional) low pressure passive fluid connecting means can be (at least in part) of the same design or can be (at least in part) of a different design.
  • the fluid working machine is designed in a way that at least one of said cyclically changing cavities is designed as a cylinder-and-piston device.
  • This design proved to be well suited for achieving the usual design parameters of fluid working machines, in particular of fluid working machines which are used for hydraulic systems. This is of course also true for fluid working machines of the synthetically commutated hydraulic machine type.
  • the fluid working machine is designed in a way that at least two of said cyclically changing cavities are displaced out of phase by at least 100 °, 105°, 110°, 115°, 120°, 125°, 130°, 135°, 140°, 145°, 150°, 155°, 160°, 165° or 170° and/or not more than 120 °, 125 °, 130°, 135 °, 140 °, 145 °, 150 °, 155 °, 160°, 165°, 170° or 175°.
  • the fluid working machine can be easily arranged on a wall of a device, the fluid working machine is used for, for example.
  • the suggested design can also prove to be advantageous with respect to the fluid flow patterns and/or with respect to the occurring pressures of the pumped fluid during the working cycle of the fluid working machine.
  • said displacement at an angle of less than 180° (or the respective number) can provide for a phase shift of less than 180° of the contraction phases of the working cycle of the fluid working machine.
  • the period where the at least two cyclically changing cavities are expanding simultaneously can provide a preferably finite or even an elongated period where no fluid flows from the cyclically changing cavities into a common fluid chamber.
  • the period where both cyclically changing cavities are expanding simultaneously can also be used for lowering the pressure within a common fluid chamber, used for distributing fluid to or receiving fluid from the cyclically changing cavities, or to allow such a depressurisation to be carried out.
  • additional depressurization means are provided.
  • Such a depressurization can prove to be necessary and/or advantageous for opening an actuated valve. This is because otherwise the actuated valve generally would have to be opened against a differential pressure between its two sides. Hence, if the differential pressure is smaller or even nonexistent, the opening movement of the actuated valve is easier. Hence, it is possible that the actuated valve can be designed with the less powerful actuator. Depending on the design of the fluid working machine it is even possible that this depressurization is a necessary requirement for being able to open the actuated valve at all.
  • At least one of said cyclically changing cavities and/or at least one of said common fluid chambers and/or at least one of said passive fluid connecting means and/or at least one of said actuated valves comprises at least one fluid depressurization means, which is preferably designed as a controllable depressurization means.
  • a fluid depressurisation means is able to release fluid from a common fluid chamber so as to reduce the pressure of fluid in it.
  • a fluid depressurising means releases fluid directly or indirectly to a reservoir of low pressure fluid brought to the fluid working machine or held within the fluid working machine.
  • a depressurization can be a necessary requirement for being able to open an actuated valve.
  • the depressurization does not necessarily have to decrease the differential pressure to zero or "almost” zero. Instead, even an only “moderate” or “substantial” decrease in differential pressure can prove to be advantageous.
  • the fluid depressurising means is preferably operable to release fluid during at least part of periods where at least two (or even all) cyclically changing cavities are expanding simultaneously (in particular those cyclically changing cavities, connecting to the same common fluid chamber), and even more preferably releases fluid only when no or essentially no fluid flows from the cyclically changing cavities into a common fluid chamber.
  • the fluid depressurising means is designed and arranged in a way that it is capable of depressurising the common fluid chamber at or shortly after the point of minimum volume of the at least one cyclically changing cavity which is latest in phase of all the at least one cyclically changing cavities.
  • the fluid depressurising means becomes incapable of depressurising the common fluid chamber at or shortly before the point of maximum volume of the at least one cyclically changing cavity which is earliest in phase of all the at least one cyclically changing cavities.
  • the fluid working machine in a way that at least one of said fluid depressurization means is designed as an orifice or as a fluid connection prolonging means, wherein said fluid connection prolonging means is designed and arranged in a way to initiate and/or to prolong an open state of at least one of said passive fluid connecting means and/or at least one of said actuated valve means.
  • a relatively easy and cheap way of designing a depressurization means can be achieved.
  • At least one of said actuated valves is designed as an electrically actuated valve, which is preferably comprising a latching device, in particular a magnetic latching device and/or a latching device for latching said actuated valve in an end position.
  • An electrical actuation of the actuated valve is generally particularly useful, since it is usually relatively easy to design a controlling unit which outputs electrical signals.
  • standard microcontrollers can be used for calculating the timing of the actuation signals.
  • the output signal from the microcontroller can be easily amplified to actuate the actuated valve, using standard amplifiers. Therefore a fluid working machine which is precisely controllable and still relatively cost-efficient can be provided.
  • the overall consumption of electrical energy can be reduced. It has to be noted that in that synthetically commutated fluid working machine the actuated valves usually remain in an end position for quite elongated time intervals. Therefore, using a latching device, it is possible to significantly reduce the electrical current, or it is even possible to completely switch off the electrical current, while still securely holding the actuated valve in an end position. Therefore the mean average of electrical energy consumed can be lowered significantly.
  • the end position can be in particular an open position and/or a closed position. Actuating the valve preferably moves the valve away from at least one of its end positions today, putting it in the opposite state of open or closed to when it was in an end position.
  • the actuated valve is a direct acting actuated valve, which allows it to actuate with maximum speed and/or minimum delay.
  • a direct acting valve can be particularly designed and arranged in a way that it primarily uses electrical energy to open and/or close the valve.
  • the actuated valve is a biased actuated valve, which naturally moves towards an end position.
  • the controlling unit preferably actively controls the actuated valves in phased relationship to cycles of cyclically changing cavity volume.
  • phased relationship to cycles of cyclically changing cavity volume we usually mean that the timing of active control of one or more actuated valves is determined with reference to the phase of the volume cycles of the cyclically changing cavities.
  • the fluid working machine typically comprises cyclically changing cavity phase determining means, such as a position sensor.
  • the fluid working machine preferably comprises a shaft position sensor, and optionally a shaft speed sensor, and the controller is operable to receive a shaft position signal from the shaft position sensor, and optionally a shaft speed signal from a said shaft speed sensor.
  • the controller will typically be operable to determine the phase of individual cyclically changing cavities.
  • actively controls we particularly include the possibilities that the controller is operable to selectively cause an actuated valve to do one, more or all of open, close, remain open and/or remain closed.
  • the controller may only be able to affect the state of an actuated valve during a portion of a working cycle. For example, the controller may be unable to open an actuated valve against a pressure difference during times when pressure within the working chamber is substantial.
  • the controller actively controls the actuated valve by transmitting a control signal either directly to an actuated valve or to an actuated valve driver, such as a semiconductor switch.
  • a control signal we particularly Include transmitting a signal which denotes the intended state of an actuated valve (e.g.
  • the controller may transmit a signal on a continuous basis and stop or change the signal to cause a change in the state of an actuated valve, for example, the actuated valve may comprise a normally closed solenoid opened valve which is held open by provision of an electric current and actively closed by switching off the current.
  • the fluid working machine is designed as a synthetically commutated hydraulic machine.
  • Such fluid working machines are particularly energy efficient, and are thus preferred.
  • Such synthetically commutated hydraulic machines generally require elaborate and hence expensive actuated valves. Therefore, the advantages of the suggested design can have a particularly large impact if applied to synthetically commutated hydraulic machines.
  • the fluid working machine is designed in a way that a pumping stroke of at least one of said cyclically changing cavities pumps a fluid volume of at least 1 ml, 2 ml, 3 ml, 4 ml, 5 ml, 6 ml, 7 ml, 8 ml, 9 ml and/or 10 ml.
  • the respective number can be in particular the pumped fluid volume of a full pumping stroke.
  • a fluid working machine can be achieved which is usable for driving hydraulics, for example. This is because in hydraulic applications, a sufficiently fast movement of the respective hydraulic components is essential. With the suggested volumes, such a sufficiently fast movement of the hydraulic components can usually be sustained.
  • a method of operating a fluid working machine comprising at least one fluid inlet port, at least one fluid outlet port and a plurality of cyclically changing cavities, wherein said fluid working machine is able to supply a fluid flow rate sufficient for hydraulic applications and/or wherein said fluid working machine can be supplied by a fluid flow rate, sufficient to propel said fluid working machine, wherein the fluid input of at least one of said plurality of cyclically changing cavities is sucked in from said fluid inlet port through at least one passive fluid connecting means, and wherein the method is modified in a way that at least one actuated valve, selectively connecting at least one of said fluid inlet ports and at least one of said cyclically changing cavities is provided, wherein said actuated valve can be actuated on a cycle-by-cycle basis.
  • FIG. 1 a schematic sketch of a synthetically commutated hydraulic pump 1 according to a first embodiment is shown.
  • the synthetically commutated hydraulic pump 1 comprises two cylinders 2, 3, in which an associated piston 4, 5 moves up and down. By the movement of the pistons 4, 5 within the cylinders 2, 3, two different pumping cavities 6, 7 of cyclically changing volume are provided.
  • the up and down movement of the pistons 4, 5 within the respective cylinder 2, 3 is initiated by a contact of a bottom part 8, 9 of the pistons 4, 5 with the radial surface 10 of the rotating crankshaft 11.
  • the crankshaft 11 is mounted off-axis on a rotating axis 12, so that the respective eccentric cams 46, 47 of the crankshaft 11 rotate eccentrically around the rotating axis 12 and work like a cam for the respective piston 4, 5.
  • the crankshaft 11 is drawn as two separate units, lying beside each other, it is preferred that the synthetically commutated hydraulic pump 1 comprises only one rotating crankshaft 11 and the two cylinders 2, 3 and pistons 4, 5 are arranged on two eccentrics 46, 47 themselves arranged along an axial direction of the crankshaft 11 behind each other.
  • the hydraulic pump 1 could be also designed in a way that he one rotating eccentric camshaft 46 is provided with the two pistons 4,5 arranged angularly spaced apart around it (which is the case in the wedding cake type pump, for example).
  • the view chosen for the synthetically commutated hydraulic pump 1 in Fig. 1 should therefore be understood as a schematic drawing, showing mainly the working principle of the synthetically commutated hydraulic pump 1.
  • the movement of the pistons 4, 5 - and therefore the changing volumes of the pumping cavities 6, 7 - is out of phase from each other.
  • the volume of the pumping cavity 6 lags the volume of the pumping cavity 7 by less than 180°, presently by 170°.
  • the phase difference between the volumes of the two pumping cavities 6, 7 is presently realized by an appropriate phase difference between the two eccentric camshafts 46, 47.
  • the second piston 5 (in Fig. 1 on the right side) is still moving out of its cylinder 3. Therefore the volume of the second pumping cavity 7 is still increasing. This can be seen by the position of the eccentric cam 46, which is some 20° before the bottom dead center of the second piston 5.
  • the rotating direction of the crankshaft 11 and eccentric cam 46 is indicated by an arrow A.
  • the fluid flow into the pumping cavity 7 is going through the bottom part 9 of piston 5. Consequently, the piston 5 has a hollow interior 14, so that fluid can pass through the piston 5.
  • the hollow interior 14 needs not necessarily to be designed as shown in Fig. 1 . Instead, it is also possible that only a bore with a relatively small diameter (as compared to the outer diameter of piston 5) is provided within the piston 5. Furthermore, a plurality of bores could also be provided.
  • a (second) groove 16 is provided within the radial surface 10 of the crankshaft 11.
  • the dimensions of the second groove 16 (in particular its circumferential dimension) is chosen in a way that the groove 16 lies in the vicinity of the opening 14 in the bottom part 9 of the corresponding piston 5, whenever the piston 5 is moving downwards, i.e. the volume of the pumping cavity 7 is expanding. Therefore, fluid can flow through the bottom part of the second piston 5, whenever the volume of the second cavity 7 is increasing (fluid flow indicated by arrow B).
  • the second groove 16 lies away from the hollow interior 14 at the bottom part 9 of piston 5. Therefore, the fluid passage is blocked and no fluid can pass through the bottom part 9 of the piston 5.
  • an appropriately arranged first groove 15 is provided on the radial surface 10 of the crankshaft 11 for corresponding interaction with the bottom part 8 of the first piston 4 as well.
  • the downward movement of the pistons 4, 5 out of the respective cylinders 2, 3 can be assisted by a spring 45, which is arranged between said parts in a way that the piston 4, 5 and the cylinder 2, 3 are pushed away from each other.
  • the first piston 4 On the left side of Fig. 1 , the first piston 4 is moving upwards into the corresponding cylinder 2. Therefore, the volume within the first pumping cavity 6 is decreasing. As can be seen from Fig. 1 , the first groove 15 does not lie in the vicinity of the hollow interior 13 of the bottom part 8 of the first piston 4. Therefore, the fluid passage through the bottom part 8 of piston 4 is blocked. Therefore, the (pressurized) fluid is pushed out of the pumping cavity 6 through the (passive) check valve 17 into a common fluid distribution chamber 19. The distribution chamber 19 is used by both cylinders 2, 3. The passive check valve 17 is open due to the pressure differences between the pumping cavity 6 and the (common) distribution chamber 19.
  • an electrically actuated valve 20 and a high-pressure valve 21 are arranged connecting to the distribution chamber 19.
  • the actuated valve 20 In the position of the actuated valve 20, as shown in Fig. 1 , the actuated valve 20 is in its closed position. Therefore, the fluid that is expelled out of one of the two cylinders 2, 3 is leaving the distribution chamber 19 through the high pressure check valve 21 towards the high pressure fluid manifold 22. From the high-pressure fluid manifold 22, the pressurized hydraulic fluid can be sent to hydraulic consumers, for example.
  • the fluid flow out of the pumping cavity 6 towards the high pressure fluid manifold 22 is indicated by an arrow C in Fig. 1 .
  • the synthetically commutated hydraulic pump 1 essentially behaves like a standard hydraulic pump, well known in the state of the art. This is the so called full stroke pumping mode of the synthetically commutated hydraulic pump 1.
  • the actuated valve 20 will remain open during a complete working cycle of the synthetically commutated hydraulic pump 1, the fluid leaving the pumping cavity 6, 7 will simply be returned towards the low pressure manifold 23, for example the crankshaft case of the crankshaft 11, from which the pumping cavities 6, 7 intake hydraulic oil through the grooves 15, 16. This is the so-called idle mode of the synthetically commutated hydraulic pump 1.
  • the actuated valve 20 will be placed into its opened position when (or before) the respective piston 4, 5 (in the present embodiment second piston 5) reaches its bottom dead center (BDC). Therefore, in the beginning of the contraction phase of the respective pumping cavity 6, 7, the hydraulic fluid leaving the pumping cavity 6, 7 will simply be returned to the low pressure fluid manifold 23. However, after a certain traveling distance of the piston 4, 5, the actuated valve 20 will be closed. Starting from this point, the hydraulic fluid, leaving the pumping cavity 6, 7 will be pressurized and leaves the distribution chamber 19 towards the high pressure fluid manifold 22 through the high-pressure check valve 21 (as indicated by arrow C).
  • the actuation pattern of the different valves is shown in more detail in the actuation graph 24 of Fig. 2 .
  • the following is shown (from top to bottom): the position 25 of the actuated valve 20; the position 26 of the second (right) piston 5; the position 27 of the second (right) check valve 18; the position 28 of the first (left) piston 4; the position 29 of the first (left) check valve 17; the position 30 of the high pressure valve 21; the pressure p 31 in the distribution chamber 19; the fluid flow rate 32 through the high-pressure valve 19.
  • both pumping cavities 6, 7 are expanding (see lines 26, 28).
  • both check valve 17, 18 would be solely of a passive check valve type, both check valves 17, 18 would be closed during the expansion phase of the respective pumping cavity 6, 7, leaving the distribution chamber 19 at an elevated pressure.
  • the actuated valve 20, used in the embodiment of Fig. 1 is not able to open against a substantial pressure difference between the distribution chamber 19 and the low pressure fluid reservoir 23. Therefore, the pressure in the distribution chamber 19 must be allowed to drop, so that the actuated valve 20 can be opened.
  • an opening pin 39 is provided for this purpose.
  • the opening pin 39 will hold the first check valve 17 in its open position for a short time after the top dead center 38 (TDC) of the first piston 4. Therefore, the expansion of the first pumping cavity 6 will lead to a pressure drop within the pumping cavity 19 (see line 31).
  • the actuated valve 20 can be opened (see line 25) and the first check valve 17 is allowed to close (see line 29).
  • the closing time of the first check valve 17 is delayed a little bit past the point when the pressure in the distribution chamber has reached its low pressure level (and the fluid connection through the first groove 15 and the bottom part 8 of first piston 4 is not yet established), the developing underpressure in the first pumping chamber 6 can even be used for opening the actuated valve 20.
  • the depressurization could also be achieved by different means, other than the presently used opening pin 39.
  • an actuated valve 20 being able to open against an elevated pressure could be used.
  • an actuated valve 20 could be used, which has an internal depressurization means.
  • the valve described in British application GB 2430246 A could be used, for example.
  • Another possibility would be to simply provide for an orifice, establishing a fluid channel with a limited cross section between the distribution chamber 19 and the low pressure fluid manifold 23.
  • the offset between the working cycles of second pumping cavity 7 and first pumping cavity 6 has to be smaller than 180°. Otherwise, there would be simply no time and/or no possibility for a depressurization of the distribution chamber 19. Therefore, it would be problematic - if possible at all - to open the actuated valve 20 for realizing an idle mode and/or a part stroke mode of the synthetically commutated hydraulic pump 1.
  • the suggested phase difference of presently 170° provides for a sufficiently large time interval between the top dead center 38 of first piston 4 and bottom dead center 41 of second piston 5 (the point where the second pumping cavity 7 starts to shrink again), so that a depressurization can be performed.
  • FIG. 3 a schematic drawing of a second embodiment of a synthetically commutated hydraulic pump 42 is shown.
  • This synthetically commutated hydraulic pump 42 can show essentially the same basic design features as the synthetically commutated hydraulic pump 1, shown in Fig. 1 .
  • the presently suggested synthetically commutated hydraulic pump 42 is arranged at a sidewall 43 of a device 44.
  • the two cylinders 3, 4 of the synthetically commutated hydraulic pump 42 are arranged at an angle, which can be for example 160°, 170° or the like.
  • the two pistons 4, 5, moving back and forth in the respective cylinders 2, 3, share the same crankshaft 11.
  • the crankshaft 11 can be simply formed as a cylindrical block and does not have to have a special shaping of its surface 10.
  • grooves 15, 16 have to be provided to allow for "breathing” of the respective pumping cavity 6, 7 through the bottom part 8, 9 of the respective pistons 4, 5.
  • a slight offset of the two cylinders 2, 3 in an axial direction of the crankshaft 11 can be provided.
  • both pistons 4, 5 to communicate with a single groove 15 in a single eccentric cam 47 forming part of crankshaft 11.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Details Of Reciprocating Pumps (AREA)
EP09001065A 2009-01-27 2009-01-27 Hydraulikpumpe Withdrawn EP2211058A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP09001065A EP2211058A1 (de) 2009-01-27 2009-01-27 Hydraulikpumpe

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EP09001065A EP2211058A1 (de) 2009-01-27 2009-01-27 Hydraulikpumpe

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014048418A1 (de) * 2012-09-26 2014-04-03 Danfoss Power Solutions Gmbh & Co. Ohg Verfahren und vorrichtung zur ansteuerung einer elektrisch kommutierten fluidarbeitsmaschine

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US3682565A (en) * 1970-08-31 1972-08-08 Donald L Yarger Multiple piston pump apparatus
EP0361927B1 (de) 1988-09-29 1994-07-27 Artemis Intelligent Power Ltd. Pumperegelungsverfahren und Tellerventil dafür
EP0685644A2 (de) * 1994-05-06 1995-12-06 Cummins Engine Company, Inc. Hochdruckpumpe für Brennstoffeinspritzsysteme
DE19644915A1 (de) * 1996-10-29 1998-04-30 Bosch Gmbh Robert Hochdruckpumpe
US6651545B2 (en) 2001-12-13 2003-11-25 Caterpillar Inc Fluid translating device
EP1429020A1 (de) * 2002-12-09 2004-06-16 Caterpillar Inc. Pumpe mit veränderlichem Abfluss
US20050067596A1 (en) 2001-12-17 2005-03-31 Rampen William H S Annular valve
GB2430246A (en) 2005-09-01 2007-03-21 Artemis Intelligent Power Ltd Valve
WO2008012587A2 (en) * 2006-07-27 2008-01-31 Artemis Intelligent Power Ltd A digital hydraulic pump/motor torque modulation system and apparatus
DE102007041021A1 (de) * 2006-09-01 2008-03-06 Robert Bosch Gmbh Steuereinrichtung für eine hydraulische Kolbenmaschine mit veränderbarem Volumenstrom
DE102007029670A1 (de) 2006-10-20 2008-04-24 Robert Bosch Gmbh Hydraulische Arbeitsmaschine

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Publication number Priority date Publication date Assignee Title
US3682565A (en) * 1970-08-31 1972-08-08 Donald L Yarger Multiple piston pump apparatus
EP0361927B1 (de) 1988-09-29 1994-07-27 Artemis Intelligent Power Ltd. Pumperegelungsverfahren und Tellerventil dafür
EP0685644A2 (de) * 1994-05-06 1995-12-06 Cummins Engine Company, Inc. Hochdruckpumpe für Brennstoffeinspritzsysteme
US5538403A (en) 1994-05-06 1996-07-23 Cummins Engine Company, Inc. High pressure pump for fuel injection systems
DE19644915A1 (de) * 1996-10-29 1998-04-30 Bosch Gmbh Robert Hochdruckpumpe
US6651545B2 (en) 2001-12-13 2003-11-25 Caterpillar Inc Fluid translating device
US20050067596A1 (en) 2001-12-17 2005-03-31 Rampen William H S Annular valve
EP1429020A1 (de) * 2002-12-09 2004-06-16 Caterpillar Inc. Pumpe mit veränderlichem Abfluss
GB2430246A (en) 2005-09-01 2007-03-21 Artemis Intelligent Power Ltd Valve
WO2008012587A2 (en) * 2006-07-27 2008-01-31 Artemis Intelligent Power Ltd A digital hydraulic pump/motor torque modulation system and apparatus
DE102007041021A1 (de) * 2006-09-01 2008-03-06 Robert Bosch Gmbh Steuereinrichtung für eine hydraulische Kolbenmaschine mit veränderbarem Volumenstrom
DE102007029670A1 (de) 2006-10-20 2008-04-24 Robert Bosch Gmbh Hydraulische Arbeitsmaschine

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014048418A1 (de) * 2012-09-26 2014-04-03 Danfoss Power Solutions Gmbh & Co. Ohg Verfahren und vorrichtung zur ansteuerung einer elektrisch kommutierten fluidarbeitsmaschine
CN104854346A (zh) * 2012-09-26 2015-08-19 丹佛斯动力系统有限责任两合公司 用于致动电子换向的流体工作机器的方法和装置
CN104854346B (zh) * 2012-09-26 2018-03-23 丹佛斯动力系统有限责任两合公司 用于致动电子换向的流体工作机器的方法和装置
US10364807B2 (en) 2012-09-26 2019-07-30 Danfoss Power Solutions Gmbh & Co. Ohg Method and device for actuating an electrically commutated fluid working machine

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