EP3808981A1 - Constant pump for use in conveying a hydraulic fluid in a closed hydraulic circuit, closed hydraulic circuit, construction machine and method for operating a constant pump in a closed hydraulic circuit - Google Patents
Constant pump for use in conveying a hydraulic fluid in a closed hydraulic circuit, closed hydraulic circuit, construction machine and method for operating a constant pump in a closed hydraulic circuit Download PDFInfo
- Publication number
- EP3808981A1 EP3808981A1 EP20000372.1A EP20000372A EP3808981A1 EP 3808981 A1 EP3808981 A1 EP 3808981A1 EP 20000372 A EP20000372 A EP 20000372A EP 3808981 A1 EP3808981 A1 EP 3808981A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- pump
- fixed displacement
- displacement pump
- fluid
- bearing
- 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- Withdrawn
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Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C11/00—Combinations of two or more machines or pumps, each being of rotary-piston or oscillating-piston type; Pumping installations
- F04C11/001—Combinations of two or more machines or pumps, each being of rotary-piston or oscillating-piston type; Pumping installations of similar working principle
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C29/00—Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 - F04C28/00
- F04C29/0021—Systems for the equilibration of forces acting on the pump
- F04C29/0028—Internal leakage control
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C11/00—Combinations of two or more machines or pumps, each being of rotary-piston or oscillating-piston type; Pumping installations
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C15/00—Component parts, details or accessories of machines, pumps or pumping installations, not provided for in groups F04C2/00 - F04C14/00
- F04C15/0003—Sealing arrangements in rotary-piston machines or pumps
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C15/00—Component parts, details or accessories of machines, pumps or pumping installations, not provided for in groups F04C2/00 - F04C14/00
- F04C15/0003—Sealing arrangements in rotary-piston machines or pumps
- F04C15/0007—Radial sealings for working fluid
- F04C15/0019—Radial sealing elements specially adapted for intermeshing-engagement type machines or pumps, e.g. gear machines or pumps
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C15/00—Component parts, details or accessories of machines, pumps or pumping installations, not provided for in groups F04C2/00 - F04C14/00
- F04C15/0003—Sealing arrangements in rotary-piston machines or pumps
- F04C15/0023—Axial sealings for working fluid
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C15/00—Component parts, details or accessories of machines, pumps or pumping installations, not provided for in groups F04C2/00 - F04C14/00
- F04C15/0003—Sealing arrangements in rotary-piston machines or pumps
- F04C15/0034—Sealing arrangements in rotary-piston machines or pumps for other than the working fluid, i.e. the sealing arrangements are not between working chambers of the machine
- F04C15/0038—Shaft sealings specially adapted for rotary-piston machines or pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C15/00—Component parts, details or accessories of machines, pumps or pumping installations, not provided for in groups F04C2/00 - F04C14/00
- F04C15/0042—Systems for the equilibration of forces acting on the machines or pump
- F04C15/0046—Internal leakage control
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C15/00—Component parts, details or accessories of machines, pumps or pumping installations, not provided for in groups F04C2/00 - F04C14/00
- F04C15/0088—Lubrication
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C15/00—Component parts, details or accessories of machines, pumps or pumping installations, not provided for in groups F04C2/00 - F04C14/00
- F04C15/06—Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet
- F04C15/064—Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet with inlet and outlet valves specially adapted for rotary or oscillating piston machines or pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C2/00—Rotary-piston machines or pumps
- F04C2/08—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
- F04C2/12—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
- F04C2/14—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons
- F04C2/18—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons with similar tooth forms
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C2240/00—Components
- F04C2240/30—Casings or housings
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C2240/00—Components
- F04C2240/50—Bearings
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C2240/00—Components
- F04C2240/80—Other components
- F04C2240/811—Actuator for control, e.g. pneumatic, hydraulic, electric
Definitions
- the invention relates to a fixed displacement pump for use in conveying a hydraulic fluid in a closed hydraulic circuit, a closed hydraulic circuit, a construction machine and a method for operating a fixed displacement pump in a closed hydraulic circuit.
- Fixed displacement pumps are known and well established in the field of hydraulics. In contrast to variable displacement pumps, fixed displacement pumps are characterized by the fact that they displace a constant volume with each rotation. Such a fixed displacement pump is, for example, in the DE2307351A disclosed.
- Typical elements of a generic fixed displacement pump are a pump housing, at least one conveying element arranged inside the pump housing in a conveying chamber and rotatably drivable about an axis of rotation for conveying purposes, the conveying element having at least one bearing axis running in the axial direction of the axis of rotation and the conveying element with the bearing axis within a Axial direction next to the delivery element, which is fixed to the pump housing and rotatable about the axis of rotation, a fluid pump inlet via which the hydraulic fluid to be delivered can be delivered from outside the constant pump on a low-pressure side into the delivery space, and a fluid pump outlet via which the delivered hydraulic fluid is removed from the delivery space can be removed from the fixed displacement pump on a high pressure
- the pump housing designates the unit that shields the pump from the outside environment. It can be provided that the pump housing also has bearing devices inside, in particular for forming the axle bearing.
- the conveying element is in particular a toothed wheel, especially a pair of toothed wheels that mesh with one another.
- the delivery element can be rotated around the axis of rotation in the delivery space, the hydraulic fluid being delivered from the fluid pump inlet to the fluid pump outlet within the fixed displacement pump as a result of the rotational movement of the delivery element within the delivery space.
- this pump is integrated into a hydraulic system, a fluid pressure is built up on the side of the fluid pump output by the connected consumer (s), so that this side (high pressure side), on which the pumped fluid leaves the fixed displacement pump, has a higher pressure level than the fluid at the fluid pump inlet (low pressure side).
- the pressure on the low-pressure side is significantly lower than that on the high-pressure side (usually up to a maximum of 3 bar) or even a negative pressure, so that the low-pressure side on which the hydraulic fluid enters the constant pump in such a case is also referred to as the suction side.
- the leakage oil is then sucked in by the fixed displacement pump itself on the suction side and fed back into the pumping chamber.
- the limiting component at this point is the shaft seal on the drive shaft.
- the hydraulic fluid is also under comparatively high pressure on the low-pressure side, for example at least greater than 10 bar, usually in the range of 20 to 30 bar, which means that the leakage oil can no longer be sucked off and / or the hydraulic fluid can rather be via the grooves or the like Equipment is pressed into the axle bearing and / or the shaft sealing ring passes / damaged and oil escapes from the fixed displacement pump.
- a characteristic of a closed hydraulic circuit is therefore that the hydraulic fluid from the hydraulic consumer is not diverted into a tank, but is returned to the pump in one or more lines. The pump is thus "clamped" in the hydraulic circuit on both sides. A defined discharge of leakage oil to a suction or low-pressure side, as described above, is then no longer possible.
- axial piston pumps are usually used in closed hydraulic circuits.
- Such hydraulic pumps allow a variable delivery volume per revolution of the respective delivery element of the pump.
- Such pumps are comparatively costly and maintenance-intensive.
- the object of the invention is to further develop a fixed displacement pump such that it is suitable for use in a closed hydraulic circuit. Ideally, it should be possible at the same time to vary the delivery volume in the closed hydraulic circuit and / or even to reverse the delivery direction.
- the fixed displacement pump has a collecting space adjoining the axle bearing of the fixed displacement pump for the leakage portion of the hydraulic fluid emerging from the axle bearing, a sealing device being present which seals the collecting space from the low-pressure side and the high-pressure side of the fixed-displacement pump, and that the fixed displacement pump has a leakage oil outlet connected to the collecting space for, in particular separate, discharge of the leakage oil from the fixed displacement pump.
- the collecting space thus no longer has a direct line connection to the low-pressure side of the fixed displacement pump, but a separate leakage oil outlet.
- the leakage oil is no longer fed directly to the hydraulic circuit on a suction side within the pump, but is discharged from the fixed displacement pump via a separate leakage oil outlet that connects the collecting chamber with a leakage oil outlet opening of the fixed displacement pump.
- the high-pressure side of the fixed displacement pump sealed off from the collecting chamber with the aid of the sealing device, but also the low-pressure side according to the invention so that the hydraulic fluid can no longer press into the collecting chamber from the low-pressure side either.
- the task of the collecting space is to collect leakage components from the axle bearing in a controlled manner. It is preferred here if the collecting space is designed in such a way that it combines the leakage oil emerging from a plurality of axle bearings and thus enables the leakage oil to be discharged centrally from the fixed displacement pump.
- the collecting space is designed as a collecting space which is pressureless in relation to the outside environment when the fixed displacement pump is in operation. This enables the leakage oil that accumulates in the collecting space to be discharged from the pump without pressure. In comparison to the external environment of the fixed displacement pump, there is no increased or decreased pressure level in the collecting space, but rather the pressure of the external environment.
- the collecting space extends through components that are stationary relative to the pump housing and / or components that are stationary relative to the at least one bearing axis.
- Stationary is to be understood to mean that the walls delimiting the collecting space do not at least partially change their position relative to the pump housing or to the bearing axis during operation of the fixed displacement pump.
- a collecting space which is stationary with respect to the pump housing can in particular also be formed directly by a pump housing part itself.
- a component that is stationary with respect to the bearing axis can in particular also be formed directly from the bearing axis itself.
- the collecting space can also be designed in such a way that it has fixed areas both with respect to the pump housing and with respect to the bearing axis.
- the collecting space has a bearing axis, in particular completely, circumferential annular space.
- he can also use one.
- the collecting space has a collecting passage opening which runs completely through the bearing axis in the axial direction from one to the other end face. This arrangement can in particular be used to connect two areas of the collecting space that are stationary relative to the pump housing.
- the collecting space can additionally or alternatively be designed in such a way that it has at least one connecting channel which connects an annular space surrounding a bearing axis or a collecting head section or a collecting passage opening with an annular space surrounding a bearing axis or a collecting head section or a collecting passage opening.
- a connection channel is designed in particular to be stationary with respect to the pump housing, for example as a connection bore.
- the collecting space comprises a collecting line into which several connecting channels open. Several leakage oil flows are thus combined centrally in the collecting line via the connecting channels.
- the collecting space thus extends here in and / or over several components.
- Particularly suitable for this purpose is, for example, a design of the collecting space or at least a partial area thereof in the bearing axis, in particular such that it passes through the bearing axis in the axial direction, in particular completely.
- the collecting space can additionally or alternatively also, in particular directly, be formed in the conveying means, in particular likewise in such a way that it passes through the bearing axis, in particular completely, in the axial direction of the axis of rotation.
- Another preferred possibility consists in forming the collecting space at least partially in a bearing bracket in which at least one bearing axis is mounted.
- a bearing bracket in which at least one bearing axis is mounted.
- Such a, in particular one-piece, bearing bracket can be provided in particular to mount two parallel bearing axles of a constant displacement pump at the same time, for example as a connecting part between two pump units of a constant displacement pump designed as a tandem pump.
- the collecting space can also be designed, for example, in a pump flange or a pump flange plate, in particular as a surface recess on the side opposite a flange side.
- the collecting space is formed in a pump cover, in particular as a surface recess on the side opposite an outside of the pump cover.
- a coupling plate of a tandem pump is, in addition or as an alternative, a coupling plate of a tandem pump. Such a coupling plate is used to mechanically couple two constant pump units to one another in a tandem arrangement known per se in the prior art.
- such a coupling plate can, for example, as a plate with two or several opposing recesses and / or through openings for receiving at least one bearing axis of each constant pump unit, which enables a comparatively compact tandem arrangement, or at least with a feed-through opening for a coupling element for drive purposes between the two constant pump units.
- the sealing device is, for example, preferably arranged as a contact seal, in particular between a pump cover and a housing part that forms, in particular, the radial conveying space relative to the axis of rotation of the at least one conveying element.
- the sealing device is preferably made of an elastic material.
- the sealing device can in particular be a polymer material, in particular a plastic polymer, for example NBR (nitrile rubber, fluorine rubber, etc. Elastomers or thermoplastics are preferred.
- Metallic seals can also be used.
- Coated seals can also be used It is particularly preferred to design the sealing device as a flat seal, ie in a design in which the height of the seal is small compared to the sealing surface and which, in particular, adapts to the adjacent sealing surfaces with its entire width of its sealing surface preferably alternatively, for example, also be designed as a molded seal, in particular with a more square cross-section with rounded edges.
- the sealing device can consist of several separate subunits. However, it can be advantageous, for example to facilitate assembly, if the sealing device is designed in one piece as a whole.
- the sealing device used to seal the collecting space from the low and high pressure sides of the fixed displacement pump at the same time then consists of a single, coherent part.
- the sealing device can also be possible for the sealing device to be constructed from a plurality of subunits, but then preferably subunits which are structurally identical to one another.
- it has at least one sealing section that completely encircles the bearing axis or the axis of rotation of the conveying element.
- the sealing device is preferably designed in such a way that it comprises two sealing sections, each completely encircling a bearing axis, and a connecting section that connects the two sealing sections to one another.
- the sealing device can in particular be designed in the form of a sealing goggle.
- the sealing device can in particular comprise at least two sealing elements which are arranged one behind the other, in particular congruent with one another, in the axial direction of the axis of rotation of a conveying element.
- the sealing device is also preferably acted upon with a tension force in the axial direction of the axis of rotation.
- the fixed displacement pump is preferably an external gear pump, comprising two juxtaposed, intermeshing gearwheels each rotating around an axis of rotation, each with external toothing, two parallel to one another, at least partially at the same height in the axial direction of the axes of rotation Bearing axles, one bearing axle carrying one gear and the other bearing axle carrying the other tooth.
- one of the bearing axles is designed as a drive axle protruding from the housing, comprising a form-fit device for engaging a drive arrangement, in particular a spline. This enables the connection of a drive train.
- only one of the bearing axles in particular the bearing axle driven by the other bearing axle, comprises a through opening that extends completely through the bearing axle in the axial direction and is open on both end faces as part of the collecting space.
- the bearing axis connected to the drive train arranged externally to the fixed displacement pump is preferably designed to be essentially solid.
- the fixed displacement pump is designed as a tandem pump with a first and a second fixed displacement pump unit.
- the tandem pump preferably has a coupling plate, according to the invention, which is arranged directly between two gear wheel pairs of the first and the second constant pump unit.
- part of the collecting space of the fixed displacement pump is formed by the coupling plate and / or a seal is present as part of the sealing device on both sides of the coupling plate in the direction of the axis of rotation of the gear pairs.
- several of the bearing axles have through openings running through them as part of the collecting space. This makes it easier to obtain a common, continuous collecting space for all of the fixed displacement pump units of the fixed displacement pump.
- such a fixed displacement pump with a plurality of fixed displacement pump units in particular exclusively, comprises a single common leakage oil outlet.
- the leakage oil of the at least two fixed displacement pump units is thus discharged into an associated collecting space and discharged from the fixed displacement pump via the single, common leakage oil outlet. It is particularly preferred if the leakage oil outlet is arranged in a pump cover, in particular a pump cover of only one of the at least two constant pump units. In addition or as an alternative, it can preferably be provided that the leakage oil outlet is arranged in a flange.
- the fixed displacement pump comprises a valve device which is connected to the fluid pump inlet and the fluid pump outlet and / or is connected upstream of the fluid pump inlet and the fluid pump outlet.
- a valve device which is connected to the fluid pump inlet and the fluid pump outlet and / or is connected upstream of the fluid pump inlet and the fluid pump outlet.
- a preferred valve function of the valve device is "switching between a direct and closed bypass from the fluid pump inlet to the fluid pump outlet and an interruption of the closed bypass". If the hydraulic fluid is fed directly from the fluid pump outlet to the fluid pump inlet, the hydraulic fluid delivered by the fixed displacement pump does not pass any hydraulic consumers in the closed circuit. With this valve function, the fixed displacement pump thus conveys hydraulic fluid in a shortened, closed hydraulic circuit, bypassing at least one hydraulic consumer, such as a hydraulic motor, from the fluid pump outlet via the valve device directly back to the fluid pump inlet. The hydraulic consumer is then inactive accordingly. If the closed direct diversion via the valve device from the fluid pump outlet to the fluid pump inlet is activated, no hydraulic fluid is conveyed in the closed hydraulic circuit to the hydraulic consumer.
- valve device can also be designed such that it enables a fluid connection between the fluid pump outlet and a first outlet of the valve device to be switched to a fluid connection between the fluid pump outlet and a second outlet of the valve device.
- This switching constellation can be used, for example, to reverse the conveying direction in that part of the closed hydraulic circuit that takes place between the valve device and the hydraulic consumer, such as a hydraulic motor.
- the valve device can additionally or alternatively also be designed in such a way that it enables the hydraulic volume delivered by the fixed displacement pump to be divided into two partial flows, specifically a partial flow returned directly to the fixed displacement pump and a partial flow passed on to the hydraulic consumer.
- valve device can also be designed in such a way that a high-pressure side of the fixed displacement pump is pressure-protected and / or a discharge line is released when a pressure threshold is exceeded on the high-pressure side.
- the valve device can comprise, for example, a preferably adjustable pressure limiting valve.
- the feed line can be fed with hydraulic fluid, for example, from a suitable feed pump.
- the feed line is connected to the closed hydraulic circuit, to the low and / or the high pressure side, via a suitable pressure protection device, for example an, in particular adjustable, pressure limiting valve.
- the feed pump is preferably a unit separate from the constant pump according to the invention. In a further preferred alternative, the feed pump can also be integrated into the constant pump according to the invention as an additional stage.
- the valve device is designed as a modular unit with a basic valve block and one or more functional valve blocks.
- the basic valve block can, for example, have a connection opening for connection to the fluid pump inlet or a line to the fluid pump inlet of the fixed displacement pump, and / or a connection opening for connection to the fluid pump outlet or a line to the fluid pump outlet of the fixed displacement pump, and / or a connection opening for connection to a motor inlet or a line for the inlet of a motor, in particular a hydraulic motor, and / or a connection opening for connection to an engine outlet or a line for the outlet of a motor, in particular a hydraulic motor.
- the basic valve block can include a connection opening for connection to a feed line. This connection makes it possible to feed hydraulic fluid into the closed hydraulic circuit from the outside, for example with the aid of a feed pump.
- the basic valve block can have a line interruption with an interruption outlet opening and an interruption inlet opening. The interruption outlet opening and the interruption inlet opening in the basic valve block itself are not in fluid connection with each other, but can be brought into fluid connection with each other in the manner described below with the aid of a suitable functional module block.
- one or more functional valve blocks are present in addition to the basic valve block.
- One or more operating functions can be obtained on the basic valve block via a function valve block.
- the design as a separate and interchangeable function module block arranged on the basic valve block enables individual adaptation of the specific functions of the valve device.
- the functional module block has a module block inlet opening and a module block outlet opening which is in fluid-conducting connection with the module block inlet opening via a valve device and / or a line connection. The hydraulic fluid thus passes through the functional module block from the inlet opening to the outlet opening.
- the functional module block can, for example, in particular be exchangeably attached to the basic valve block in such a way that the interruption outlet opening is in fluid connection with the module block inlet opening and the module block outlet opening is in fluid connection with the interruption inlet opening.
- the hydraulic fluid especially coming from the fixed displacement pump in the closed hydraulic circuit, is passed from the basic valve block into the functional module block and from there back to the basic valve block before it is fed to a hydraulic consumer, for example a hydraulic motor.
- the basic valve block thus represents a type of adapter that is supplied with hydraulic fluid in a closed system by the fixed displacement pump and on which various functions can be implemented.
- at least one functional module block is connected to the basic valve block.
- the functional module block can correspondingly pure through lines for the hydraulic fluid and / or, in particular, switchable switching devices, in particular at least one valve, very particularly at least one 2/2-way valve and / or at least a 4/2-way valve and / or a, in particular continuously variable, flow divider, specifically a variable, in particular proportionally controllable, flow control valve.
- the functional module block is designed in such a way that it enables switching between two inlet and two outlet openings, in particular for example via a switchable 4/2-way valve. With this function, a closed hydraulic circuit routed through the function module block to a consumer can be reversed with regard to its flow direction.
- the function module block can also be designed as a feed-through bridge and thus enable a static feed-through of defined inputs to defined outputs.
- the function module block can also be designed in such a way that it can be used to switch a feed function on and off, via which hydraulic fluid is fed from the outside into the closed hydraulic circuit.
- the function module block divides an incoming hydraulic volume flow into two outgoing hydraulic volume flows, for example with the aid of a flow control valve.
- a flow control valve for example, it is possible, for example, to vary the volume flow component that is passed on in the flow direction to a hydraulic consumer, and the volume flow component that is passed back to the pump, for example bypassing.
- a further development shown with the aid of a function module block can also be a feed pressure bypass, which is particularly helpful for the cold start phase. With the aid of the feed pressure bypass, hydraulic fluid can be diverted directly to the fixed displacement pump, bypassing the consumer. The hydraulic fluid is therefore only circulated in a partial segment in the closed hydraulic circuit and can heat up more quickly in this way.
- the fixed displacement pump deliver in the line part located downstream in the conveying direction from the fixed displacement pump to the consumer.
- a suitable bypass line for example also in the basic module block, and a suitable valve, in particular in the functional module block. It is essential for the bypass line that it enables the hydraulic fluid delivered by the fixed displacement pump to be returned from the high pressure side to the low pressure side, bypassing the consumer.
- the basic valve block is designed for the simultaneous connection of at least two functional module blocks.
- the connected function module blocks preferably implement different functionalities.
- the two function module blocks are ideally designed in such a way that they can perform at least one of the functionalities "on / off function” and / or “direction reversal” and / or “flow divider” or “flow control” on a connected consumer, especially hydraulic motor, are designed, the respective functionality being related to the behavior of the connected consumer driven by the closed hydraulic circuit.
- the valve device in particular the basic valve block, is preferably designed, independently of the above statements, in such a way that it has a connection for a feed pump and that it has a switching device, in particular pressure-protected, for draining hydraulic fluid from the closed circuit into a discharge line leading to a line connection, for example due to thermal effects and / or for partial cooling of the hydraulic fluid circulating in the closed hydraulic circuit.
- a part of hydraulic fluid can be withdrawn from outside the closed hydraulic circuit and supplied to the closed hydraulic circuit in a controlled manner. This can serve in particular to compensate for leakage oil losses and / or for cooling purposes of the hydraulic fluid volume circulating in the closed hydraulic circuit.
- a pressure-protected switching device is, for example, a pressure limiting valve.
- valve device can be designed as a structural unit that is structurally connected with the fixed displacement pump or as a structural unit that is separate from the fixed displacement pump but is in fluid connection with it.
- the invention is also directed to these two variants.
- Another aspect of the invention relates to a closed hydraulic circuit, comprising a constant displacement pump according to the invention, in particular with a valve device, as described above.
- the closed hydraulic circuit accordingly has, in addition to a fixed displacement pump according to the invention, a hydraulic consumer supplied with hydraulic fluid from the fixed displacement pump, in particular a hydraulic motor, with a fluid motor input and a fluid motor output, a supply line leading to hydraulic fluid which connects the fluid pump output to the fluid motor input, and a hydraulic fluid returning supply line which connects the fluid motor output to the fluid pump input.
- the invention also relates to a construction machine, in particular a road finisher, a feeder, a road milling machine, a stabilizer, a recycler, a garbage or earth compactor, an earth or road roller, with at least one closed hydraulic circuit according to the invention.
- Another aspect of the invention finally relates to a method for operating a fixed displacement pump operated in a closed hydraulic circuit, in particular a fixed displacement pump according to the invention.
- the method according to the invention initially comprises a conveyance of hydraulic fluid with the aid of the fixed displacement pump to a high pressure side of the closed hydraulic circuit.
- a pressure level (“high pressure side") that is higher than that on the low-pressure side is generated in the closed hydraulic circuit between the fluid outlet on the fixed displacement pump and the at least one hydraulic consumer and maintained during operation.
- a hydraulic consumer in particular a hydraulic or hydraulic motor, is driven with the aid of the hydraulic fluid carried on the high-pressure side.
- the leakage oil is diverted from the fixed displacement pump, in particular separately from the hydraulic fluid circulating within the closed hydraulic circuit, whereby a volume fraction of hydraulic fluid is removed from the closed hydraulic circuit as a result.
- the discharge takes place particularly preferably without pressure or without a pressure difference in relation to the external environment of the fixed displacement pump.
- the leakage oil is also diverted from the fixed displacement pump preferably via one, in particular exclusively one, leakage oil outlet of the fixed displacement pump.
- the method according to the invention also finally includes feeding hydraulic fluid into the closed hydraulic circuit to compensate for the leakage oil diverted from the closed hydraulic circuit in the preceding steps in order to keep the total volume of hydraulic fluid in the closed hydraulic circuit at least substantially as constant as possible.
- a suitable feed device with, in particular, a feed pump which is separate from the constant pump according to the invention and which can also be a constant pump, can be provided.
- the collection of leakage oil takes place at least partially via a through opening arranged in a bearing axis.
- the collection thus takes place at least partially via a partial area of the collecting space that rotates with the conveying element about the axis of rotation. It is ideal if the leakage oil is collected via a collecting space which at least partially rotates with the conveying element about the axis of rotation and in particular extends through it, especially along the axis of rotation, and which has at least a partial area that is stationary opposite a pump housing of the fixed displacement pump, in particular in the area of the leakage oil outlet.
- the collecting space is preferably sealed against both the high pressure side and the low pressure side of the fixed displacement pump with the aid of a sealing device, especially with the aid of a sealing device, as described in more detail for the fixed displacement pump according to the invention .
- the constant pump is designed as a tandem pump with a first constant pump unit and a second constant pump unit.
- leakage oil quantities are collected separately for each fixed displacement pump unit.
- the two closed hydraulic circuits operated by the two fixed displacement pump units are also supplied with hydraulic fluid via a common feed pump which has supply lines to both closed hydraulic circuits.
- Figure 1 shows an example of a construction machine 1 which is particularly suitable for the use of the arrangement according to the invention or for the use of the method according to the invention, as described in more detail below.
- the construction machine 1 according to Figure 1 Specifically, it is a so-called road finisher, the essential elements of which are a machine frame 2, driving devices 3, a control stand 4, a drive motor 5, a material bunker 6 and a screed 7.
- the structure and mode of operation of such a construction machine 1 or in particular of the in Figure 1 road paver shown is known per se. In operation, the construction machine moves in or against the direction of travel A over the ground (in the case of a road paver, direction A also represents the paving direction of the same).
- FIG. 2 illustrates the basic structure of a closed hydraulic circuit 8 according to the invention.
- Essential elements of such a closed hydraulic circuit 8 are a pump designed as a constant pump 9 with a pump outlet 10 and a pump inlet 11, as well as a hydraulic consumer 12, in particular a hydraulic motor, with a motor inlet 13 via the Hydraulic fluid reaches the hydraulic consumer and drives it, and with a motor outlet 14, via which the hydraulic fluid leaves the hydraulic consumer 14 again.
- Hydraulic fluid conveyed by the fixed displacement pump 9 is conveyed from the pump outlet 10 to the engine inlet 13 via a feed line 15.
- This sub-area of the closed hydraulic circuit 8 is also referred to as the high pressure side.
- Hydraulic fluid emerging from the hydraulic consumer 12 in the closed hydraulic circuit 8 is fed back to the fixed displacement pump 9 via a return line 16 which connects the motor outlet 14 to the pump inlet 11.
- the sub-area of the closed hydraulic circuit 8 between the motor outlet 14 and the pump inlet 11 is also referred to as the low-pressure side.
- the fixed displacement pump 9 can be connected to a drive element, for example an internal combustion engine or a pump transfer gear, via a drive shaft 17.
- the hydraulic consumer 12 can drive an output shaft 18 via which an element to be driven, for example a conveying device, a travel drive, an exciter, etc., is set in motion.
- the closed hydraulic circuit 8 can also include the valve device 19.
- This can include a base valve block 20 and two, for example have these attached, functional module blocks 21.
- the hydraulic fluid conveyed by the fixed displacement pump 9 via the pump outlet 10 first passes the basic valve block 20 and then the hydraulic consumer 12. Via the motor outlet 14, the hydraulic fluid conveyed is then returned to the fixed displacement pump 9, again passing through the basic valve block 20 in the closed hydraulic circuit 8.
- Part of the fixed displacement pump 9 is a collecting space 22 in which leakage oil that occurs during operation of the fixed displacement pump 9 is collected.
- the leakage oil collected within the fixed displacement pump 9 can be discharged from the interior of the fixed displacement pump 9 via a leakage oil outlet 23, in particular without pressure in relation to the external environment of the fixed displacement pump 9.
- a discharge line 24 connected to the leakage oil outlet 23 can be provided, which discharges the leakage oil collected from the leakage oil outlet 23 into a tank 25.
- a feed device 26 can be provided, which is provided to compensate for the leakage oil losses in the closed hydraulic circuit 8.
- This feed device 26 can comprise a feed pump 27 separate from the constant pump 9 of the closed hydraulic circuit 8, for example a conventional constant pump in an open hydraulic circuit, which is connected via a feed line 28 to the closed hydraulic circuit 8 and / or one of its components, such as the valve device in the present exemplary embodiment 19, is connected in such a way that hydraulic fluid can be fed into the closed hydraulic circuit 8 to compensate for the leakage oil losses.
- FIG 3 shows a cross section through an exemplary fixed displacement pump 9 for a more detailed illustration of a possible delivery principle of the fixed displacement pump, as it can in particular also be used to implement a fixed displacement pump according to the invention.
- the flow direction of the hydraulic fluid delivered by the fixed displacement pump 9 is in Figure 3 indicated with arrows.
- the in Figure 3 The embodiment shown is the fixed displacement pump 9 is an external gear pump, the invention in principle also relating to other specific configurations of the fixed displacement pump 9 with different delivery principles.
- Hydraulic fluid reaches the interior of a pump housing 29 of the fixed displacement pump 9 via the pump inlet 11.
- the delivery rate of the hydraulic fluid is generated by, for example, 2 conveyor elements 30 designed as adjacent, meshing external gears.
- the pump inlet 11 (“low-pressure side”) and the pump outlet 10 (“high-pressure side”) are located opposite one another on the longitudinally extending side regions.
- the conveying elements 30, which can be rotated about the respective rotational axis R, are each mounted on a bearing axis 31 on the pump housing 29 via an axle bearing (in Figure 3 not shown) rotatably mounted.
- a return of leakage oil flows occurring during operation of the fixed displacement pump 9 is therefore not possible via a feed on a suction side, as is the case with conventional fixed displacement pumps.
- the fixed displacement pump 9 therefore has the collecting chamber 22, which is described in greater detail below, for the separate collection and combination of leakage oil flows that are sealed off from the low-pressure side and the high-pressure side.
- FIG 4 shows a constant displacement pump 9 according to the invention in a tandem arrangement with two constant displacement pump units 9A and 9B.
- a mounting flange 37 is provided, via which the fixed displacement pump 9 can be flange-mounted on a drive element, for example a drive motor or a pump transfer case.
- the two constant pump units 9A and 9B are arranged in series with one another, so that only one drive shaft 17 is required to drive the two constant pump units 9A and 9B.
- Each of the two constant pump units 9A and 9B supplies a closed hydraulic circuit (in Figure 4 Not shown).
- the two pump inlets 11 are arranged on the front of the fixed displacement pump 9 in Figure 4 .
- the two constant pump units 9A and 9B or the constant pump 9 has a common leakage oil outlet 23 on the side of the pump housing 29 opposite the drive shaft 17. Via this exclusively one leakage oil outlet 23 of the fixed displacement pump 9, all of the leakage oil collected in the collecting space described in more detail below from both fixed displacement pump units 9A and 9B is discharged from the fixed displacement pump 9. Separate collection and discharge for each of the two constant pump units 9A and 9B is, however, also possible.
- the pump housing 29 is constructed in several parts and comprises two housing sleeves 29A and 29B, which are each assigned to a constant pump unit 9A and 9B, a flange plate 29C with the mounting flange 37 and a coupling plate 29A, via which the housing sleeves 29A and 29B of the two constant pump units 9A and 9B are connected to each other.
- connecting screws 32 are also provided, which pass through the two housing sleeves 29A and 29B and the coupling plate 29D up to the flange plate 29C and are in thread engagement in the flange plate 29C.
- the Leakage oil outlet 23 is arranged, for example, in a flange, in particular the flange plate 29C or the coupling plate 29D.
- FIG. 3 is a cross-sectional view with the plane I from FIG Figure 4 and the viewing direction according to the viewing arrow I. Figure 4 .
- the cutting plane thus runs along the two axes of rotation R.
- the in the Figures 5A and 5B The fixed displacement pump shown differs slightly from the one in Fig. 4 shown fixed displacement pump.
- the “inner workings" are essentially identical. A relevant difference is that in the embodiment, the pump cover can be designed to be integrated.
- the pump housing 29 is composed of several individual components, specifically 29A to 29E. In contrast to the variant according to Fig.
- the fixed displacement pump 9 in the present exemplary embodiment also comprises two individual fixed displacement pump units 9A and 9B.
- the invention also extends in particular to those constant pumps which have only one constant pump unit, for example comprising the elements 29A, 29C and 29E with a gear pair. However, only one constant pump unit or more than two constant pump units can also be provided.
- each fixed displacement pump unit comprises a pair of gearwheels 31A, 31B that mesh with one another as the conveying element 30.
- the gears are external gears.
- the fixed displacement pump is driven by the drive shaft 17 rotating about the axis of rotation R (R1), which can be designed in one piece with the gear 31A of the first fixed displacement pump unit 9A. It is essential that the drive shaft 17 and the first gear 31A are connected to one another in a rotationally fixed manner.
- the meshing engagement of the gear 31A with the teeth of the second gear 31B causes the second gear 31B to rotate about the axis of rotation R2.
- Each gear wheel 31A and 31B comprises in the axial direction of the respective rotational axis R1 and R2 on both sides in each case a bearing axis 33 which protrudes in the axial direction relative to the respective gear wheel 31A / 31B and which in the Figure 5A are designated with the index numbers 33.1 to 33.8 for better assignment.
- the bearing axis 33.1 projects beyond the drive shaft projecting beyond the pump housing 29.
- On the axis of rotation R1 of the bearing axis 33.1 opposite to the drive gear 31A is the bearing axis 33.2.
- the gear 31B engages with the gear 31A with the two bearing axles 33.3 and 33.4 protruding opposite one another in the axial direction of the axis of rotation R2.
- the gear 31C includes the bearing axles 33.5 and 33.6 and the gear 31D the bearing axles 33.7 and 33.8.
- the bearing axis 33.2 of the first constant pump unit 9A via a connecting pin 34 which is positioned non-rotatably about the axis of rotation R1 in the bearing axis 33.2, which at the same time engages non-rotatably in the bearing axis 33.5 of the second constant pump unit 9B, in Drive connection is.
- the second constant pump unit 9B is thus driven via the first constant pump unit 9A and the non-rotatable connection achieved via the connecting pin 34.
- the bearing axles 33 are each mounted in axle bearings 35 (in association with the bearing axles 33.1 to 33.8 in the axle bearings 35.1 to 35.8) so that they can rotate about the respective rotational axis R1 and R2, whereby the axle bearings 35 can in particular be designed as slide bearings .
- the gears 31A to 31D can be axially secured with the aid of bearing brackets 36A and 36B for the first fixed displacement pump unit 9A and 36C and 36D for the second fixed displacement pump unit 9B, which are arranged in the interior of the pump housing 29.
- the bearing brackets can form the axle bearings 35.1 to 35.8.
- the gears 31A to 31D protrude in the radial direction to the respective axis of rotation R1 and R2 with respect to the radial extent of the respective axle bearings 35.1 to 35.8, so that they are positively prevented by the bearing brackets 36 from any significant axial displacement along the respective axis of rotation R1, R2.
- FIG. 5B shows, for a more detailed illustration of the overall extent of the collecting space 22, this free of any contour lines extending into the plane of view of the cross-sectional view. To further improve the overview, the connecting pin 34 has also been omitted. In Figure 5B some of the exit points 39.1 to 39.8 of the leakage oil from the axle bearings 35.1 to 35.8 in the collectively connected and hollow space 22 are designated for the respective axle bearings 35.1 to 35.8.
- a collecting cavity section 22.1 that encircles the bearing axis 33.1 in a ring shape. This is formed in the flange plate 29C and merges into a channel bore 22.2, which can also be formed inside the flange plate 29C.
- a connection to a hollow space 22.3 present at the end of the bearing axis 33.3 is formed, which is connected to the bearing axis 33.3, the gear wheel 31B and the bearing axis 33.4 along the axis of rotation Through hole 22.4 passing through R2 passes.
- the collecting space 22 merges into a subarea 22.5 which is stationary with respect to the pump housing 29 and in which the exit points 39.4 and 39.7 are located.
- Comparable collecting space areas 22.9 to 22.13 can also be found at the exit points 39.2, 39.5 and 39.6, which are collected in this sub-area of the collecting space 22 and in the direction of arrow P4, P5 to Leakage oil outlet 23 can flow.
- a sealing device 40 which in the present exemplary embodiment comprises several sealing units which, in the axial direction of the axes of rotation R1 and R2, one behind the other between a) the flange plate 29C and the bearing bracket 36A and the pump housing 29A, b) the coupling plate 29D, the bearing bracket 36B and the pump housing 29A, c) the coupling plate 29D, the bearing bracket 36C and the pump housing 29B and d) the pump housing 29B, the bearing bracket 36D and the pump housing cover 29E.
- the sealing device 40 has a conventional housing seal 40A and a collecting space seal 40B according to the invention.
- a conventional housing seal 40A and a collecting space seal 40B according to the invention.
- Figure 6 shows first the structure of a sealing device 40 according to the prior art, ie for a fixed displacement pump 9 *, which is not suitable for use in a closed hydraulic circuit, but can only be operated sensibly in an open hydraulic circuit system.
- Structural and / or functionally corresponding components are denoted by "*" with reference to the preceding statements on the embodiment of the fixed displacement pump according to the invention.
- the housing seal 40A there is a partial plenum seal 40B * which provides the Collecting space 22 seals only against the high pressure side of the fixed displacement pump 9 *.
- the compartment 22.3 * is specified, which is located at the front in the axial direction R2 to the bearing axis 33.3 *) via grooves 41 to the suction side of the fixed displacement pump 9 * on the side of the pump inlet 11 * (in Fig. 6 indicated by the two dashed arrows).
- the vacuum required for this on the suction side of the fixed displacement pump 9 * is generated by the delivery function of the fixed displacement pump 9 * in an open hydraulic circuit or it can be provided that there is only a very low pressure level here, in particular at a maximum of 3 bar. A seal against the suction side is therefore also not available due to the function.
- This arrangement is not suitable for operating the fixed displacement pump 9 * in a closed circuit, since the suction effect required on the pump inlet side can then no longer be generated or the pressure on the low-pressure side is significantly higher, in particular greater than 10 bar.
- the fixed displacement pump has a plenum seal 40B, which is designed such that it seals the plenum at the same time against the low pressure side (ie towards the pump inlet side) and against the high pressure side (ie towards the pump outlet side).
- the collecting space seal 40B comprises two completely and closed circumferential recesses 42A and 42B which are connected to one another via a connecting web 42C.
- the collecting space seal 40B can be designed in one piece, for example in the form of a sealing gland. However, several individual subunits can also be used. Each of the circular recesses revolves around one of the two axes of rotation R1, R2.
- the collecting space seal 40B is clamped between the flange plate 29C and the bearing bracket 36A. Further plenum seals 40B can also be clamped between the bearing bracket 36B and the coupling plate 29D, the coupling plate 29D and the bearing bracket 36C and the bearing bracket 36D and the pump housing cover 29E ( Figure 5b ). The required clamping force can be generated via the connecting screws 32.
- Each collecting chamber seal 40B has in common that it can be designed as a flat seal and / or molded seal and / or the collecting chamber 22 of one of the constant pump units 9A and 9B inside opposite the delivery chamber 38, be it towards the high pressure side and / or the low pressure side of the constant pump 9 , seals.
- the constant displacement pump 9 has a separate connection between the collecting space 22 and the external environment of the constant displacement pump, in particular the leakage oil outlet 23.
- the collecting space 22 can therefore also be without pressure (or without pressure difference) with respect to the external environment.
- Fig. 8 illustrates a possible arrangement of a constant pump 9 according to the invention in one embodiment of a hydraulic circuit diagram.
- the constant pump 9 is connected in fluid-conducting connection via the supply line 15 and the return line 16 to the valve device 19, comprising a basic valve block 20 on which two functional module blocks 21 are arranged.
- the fixed displacement pump in relation to the closed Hydraulic circuit 8 can be operated in both conveying directions, as a result of which the feed line 15 then becomes the return line 16 and vice versa.
- the hydraulic consumer 12 in the present case in the form of a hydraulic motor, adjoins the valve device 19 in the conveying direction. This is also in fluid-conducting connection with the valve device 19 via a supply line 15 and a return line 16.
- the basic valve block 20 comprises a pump input PA, a motor output MA, a motor input MB and a pump output PB.
- a feed pump 43 is connected to the basic valve block 20 of the valve device 19 via a feed line 44.
- the task of the feed pump 43 is to suck in hydraulic fluid from the tank 25 and to feed it into the closed hydraulic circuit 8 to compensate for leakage oil losses.
- a feed connection S is provided on the basic valve block 20 of the valve device 19, to which a feed line running within the basic valve block 20 connects.
- a feed filter 45 is also provided in the feed line.
- the closed hydraulic circuit is pressure-protected via the pressure relief valve 47.
- the feed line is connected within the basic valve block 20 via a pressure limiting valve 46 in a pressure-protected manner with respect to the feed line 15.
- a further pressure limiting valve 47 can also be provided to the return line 16.
- the valve device 19 can further include, for example in the basic valve block 20, pressure limiting devices, in particular in the form of pressure limiting valve 46 ', which enable a controlled discharge of excess hydraulic fluid from the closed hydraulic circuit 8, for example due to thermal expansion effects.
- One or more of the pressure relief valves 46, 46 'and / or 47 can be controlled.
- the hydraulic circuit shown is in particular the functional module blocks 21A and 21B attached to the basic valve block 20, through which the hydraulic fluid is passed successively from the fixed displacement pump 9 before it is passed on to the hydraulic consumer 12.
- the Figures 9A through 9D show the valve device 19 with the basic valve block 20 and respectively different attached functional module blocks 21.
- functionalities that can be achieved in conventional closed hydraulic circuits with a variable displacement pump can also be imitated when using the constant pump described above, such as For example, switching the delivery direction on the hydraulic consumer, varying the delivery rate, etc.
- the function module block 21A includes, for example, an on / off function.
- hydraulic fluid fed into the valve device 19 via the input PA can be returned directly to the pump output PB, bypassing the connections MA and MB and thus bypassing a consumer connected to MA / MB, as shown in FIG Figure 9A switching position shown.
- hydraulic fluid entering the valve device 19 is passed through the input PA to the outputs MA or MB, depending on the switching position of the functional valve block 21B, and thus passed on to the hydraulic consumer.
- FIG. 9B An alternative embodiment according to Figure 9B is the function module block 21C in the form of a non-switchable transmission bridge.
- the variant shown thus does not allow a change in direction of the sub-area of the connected hydraulic circuit 8 that is located downstream of the valve device 19, starting from the fixed displacement pump 9.
- FIG 9C is compared to the previous statements according to Figures 9A and 9B the function module block 21A is replaced by the function module block 21D.
- the in Figure 9C In this context, there is complete, stepless variability between the maximum delivery volume and a zero delivery volume both in terms of the delivery volume fed in via the output MA and through the outlet MB.
- the delivery device in the circuit part of the closed hydraulic circuit 8 can be selected between the connections MA and MB via the function module 21B.
- FIG 10 finally, describes the design of a valve device 19, for example for the case of use in a tandem pump arrangement, as described, for example, in the preceding figures.
- a valve device 19 is assigned to each of the constant pump units.
- One of the two valve devices can have a plug element 48 which interrupts the connection to the tank line T via the pressure limiting valve 46, as shown in the previous embodiments.
- This valve can also have a modular design in order to enable the basic block 20 to be adapted to the respective design as easily as possible.
- FIG. 11 finally illustrates essential steps of a method according to the invention.
- hydraulic fluid is conveyed 49 with the aid of a fixed displacement pump to a high pressure side of a closed hydraulic circuit, in particular a closed hydraulic circuit, as described above.
- the conveying 49 drives 50 a hydraulic consumer, in particular a hydraulic motor, with the aid of the hydraulic fluid carried on the high pressure side in the closed hydraulic circuit.
- a collection 52 of leakage oil takes place within the fixed displacement pump in a separate collection chamber sealed off from the low-pressure side and also from the high-pressure side of the closed hydraulic circuit, which is then derived from the fixed-displacement pump in step 53 . It is further provided that hydraulic fluid is fed into the closed hydraulic circuit to compensate for the leakage oil diverted from the closed hydraulic circuit in steps 52 and 53.
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Abstract
Die Erfindung betrifft eine Konstantpumpe zur Verwendung zum Fördern eines Hydraulikfluids in einem geschlossenen Hydraulikkreislauf, einen geschlossenen Hydraulikkreislauf, eine Baumaschine sowie ein Verfahren zum Betrieb einer Konstantpumpe in einem geschlossenen Hydraulickreislauf.The invention relates to a fixed displacement pump for use in conveying a hydraulic fluid in a closed hydraulic circuit, a closed hydraulic circuit, a construction machine and a method for operating a fixed displacement pump in a closed hydraulic circuit.
Description
Die Erfindung betrifft eine Konstantpumpe zur Verwendung zum Fördern eines Hydraulikfluids in einem geschlossenen Hydraulikkreislauf, einen geschlossenen Hydraulikkreislauf, eine Baumaschine sowie ein Verfahren zum Betrieb einer Konstantpumpe in einem geschlossenen Hydraulickreislauf.The invention relates to a fixed displacement pump for use in conveying a hydraulic fluid in a closed hydraulic circuit, a closed hydraulic circuit, a construction machine and a method for operating a fixed displacement pump in a closed hydraulic circuit.
Konstantpumpen sind im Bereich der Hydraulik bekannt und bereits bestens etabliert. Konstantpumpen zeichnen sich im Gegensatz zu Verstellpumpen dadurch aus, dass sie bei jeder Umdrehung ein konstantes Volumen verdrängen. Eine solche Konstantpumpe ist beispielsweise in der
Im Betrieb einer solchen Konstantpumpe treten regelmäßig Leckageströme aus. Dabei gelangt ein Teil des Hydraulikfluids, beispielsweise zwischen dem Achslager und der Lagerachse des Förderelementes, aus dem Förderstrom des Hydraulikfluids und wird somit nicht mehr vom Förderelement zur Hochdruckseite gefördert. Für Konstantpumpen ist es in diesem Zusammenhang bekannt, eine Einrichtung zum Abführen eines aus dem Förderraum über das Achslager austretenden Leckageanteils des Hydraulikfluids, vorzusehen. Eine solche Einrichtung kann beispielsweise in einer Nut bestehen, die gegenüber zum Förderraum vom Achslager zur Niederdruckseite der Konstantpumpe führt. Wird eine solche Konstantpumpe in einem offenen Hydraulikkreislauf betrieben, herrscht an der Niederdruckseite ein gegenüber der Hochdruckseite deutlich geringerer Druck (üblicherweise bis maximal 3 bar) oder sogar ein Unterdruck, so dass die Niederdruckseite, auf der Hydraulikfluid in die Konstantpumpe eintritt, in einem solchen Fall auch als Saugseite bezeichnet wird. Das Leckageöl wird dann von der Konstantpumpe auf der Saugseite selbst angesaugt und dem Förderraum wieder zugeführt. Begrenzendes Bauteil ist an dieser Stelle der Wellendichtring der Antriebswelle.Leakage flows regularly occur when such a fixed displacement pump is in operation. In this case, part of the hydraulic fluid, for example between the axle bearing and the bearing axis of the conveying element, comes out of the conveying flow of the hydraulic fluid and is therefore no longer conveyed by the conveying element to the high-pressure side. In this context, it is known for fixed displacement pumps to provide a device for discharging a leakage portion of the hydraulic fluid emerging from the delivery space via the axle bearing. Such a device can consist, for example, in a groove that leads from the axle bearing to the low-pressure side of the fixed displacement pump opposite to the delivery chamber. If such a constant pump is operated in an open hydraulic circuit, the pressure on the low-pressure side is significantly lower than that on the high-pressure side (usually up to a maximum of 3 bar) or even a negative pressure, so that the low-pressure side on which the hydraulic fluid enters the constant pump in such a case is also referred to as the suction side. The leakage oil is then sucked in by the fixed displacement pump itself on the suction side and fed back into the pumping chamber. The limiting component at this point is the shaft seal on the drive shaft.
Eine solche Anordnung ist allerdings nicht für den Einsatz in einem geschlossenen Hydraulickreislauf geeignet, da dann beispielsweise der vorstehend beschriebene Saugeffekt nicht mehr auftritt bzw. des sehr geringe Druckniveau auf der Saugseite nicht mehr vorliegt. In einem geschlossenen Hydraulikkreislauf steht das Hydraulikfluid auch auf der Niederdruckseite unter vergleichsweise hohem Druck, beispielsweise wenigstens größer 10 bar, üblicherweise im Bereich von 20 bis 30 bar, wodurch das Leckageöl nicht mehr abgesaugt werden kann und/oder das Hydraulikfluid vielmehr über die Nuten oder ähnliche Einrichtungen in das Achslager hineingedrückt wird und/oder den Wellendichtring passiert/beschädigt und dadurch Öl aus der Konstantpumpe austritt. Kennzeichnend für einen geschlossenen Hydraulikkreislauf ist somit, dass das Hydraulikfluid vom hydraulischen Verbraucher nicht in einen Tank abgeleitet wird, sondern in einer oder mehreren Leitungen zurück zur Pumpe geführt wird. Die Pumpe ist damit beidseitig in den Hydraulikkreislauf "eingespannt". Ein definiertes Abführen von Leckageöl zu einer Saug- bzw. Niederdruckseite hin, wie vorstehend beschrieben, ist dann nicht mehr möglich.However, such an arrangement is not suitable for use in a closed hydraulic circuit, since then, for example, the suction effect described above no longer occurs or the very low pressure level on the suction side no longer exists. In a closed hydraulic circuit, the hydraulic fluid is also under comparatively high pressure on the low-pressure side, for example at least greater than 10 bar, usually in the range of 20 to 30 bar, which means that the leakage oil can no longer be sucked off and / or the hydraulic fluid can rather be via the grooves or the like Equipment is pressed into the axle bearing and / or the shaft sealing ring passes / damaged and oil escapes from the fixed displacement pump. A characteristic of a closed hydraulic circuit is therefore that the hydraulic fluid from the hydraulic consumer is not diverted into a tank, but is returned to the pump in one or more lines. The pump is thus "clamped" in the hydraulic circuit on both sides. A defined discharge of leakage oil to a suction or low-pressure side, as described above, is then no longer possible.
Aus diesem Grund wird in geschlossenen Hydraulikkreisläufen üblicherweise auf Axialkolbenpumpen zurückgegriffen. Derartige Hydraulikpumpen ermöglichen ein variables Fördervolumen pro Umdrehung des jeweiligen Förderelementes der Pumpe. Derartige Pumpen sind allerdings vergleichsweise kosten- und wartungsintensiv.For this reason, axial piston pumps are usually used in closed hydraulic circuits. Such hydraulic pumps allow a variable delivery volume per revolution of the respective delivery element of the pump. Such pumps, however, are comparatively costly and maintenance-intensive.
Hiervon ausgehend ist es die Aufgabe der Erfindung, eine Konstantpumpe dahingehend weiterzuentwickeln, dass diese für eine Verwendung in einem geschlossenen Hydraulikkreislauf geeignet ist. Idealerweise soll es dabei gleichzeitig möglich sein, in dem geschlossenen Hydraulikkreislauf das Fördervolumen zu variieren und/oder sogar die Förderrichtung umzukehren.Starting from this, the object of the invention is to further develop a fixed displacement pump such that it is suitable for use in a closed hydraulic circuit. Ideally, it should be possible at the same time to vary the delivery volume in the closed hydraulic circuit and / or even to reverse the delivery direction.
Die Lösung der Aufgabe gelingt mit einer Konstantpumpe zur Verwendung zum Fördern eines Hydraulikfluids in einem geschlossenen Hydraulikkreislauf, mit einem geschlossenen Hydraulickreislauf, mit einer Baumaschine sowie mit einem Verfahren zum Betrieb einer Konstantpumpe in einem geschlossenen Hydraulikkreislauf gemäß den unabhängigen Ansprüchen. Bevorzugte Weiterbildungen sind in den abhängigen Ansprüchen angegeben.The problem is solved with a fixed displacement pump for use to convey a hydraulic fluid in a closed hydraulic circuit, with a closed hydraulic circuit, with a construction machine and with a method for operating a fixed displacement pump in a closed hydraulic circuit according to the independent claims. Preferred developments are given in the dependent claims.
Ein wesentlicher Aspekt der Erfindung liegt darin, dass die Konstantpumpe einen an das Achslager der Konstantpumpe angrenzenden Sammelraum für den aus dem Achslager austretenden Leckageanteil des Hydraulikfluids aufweist, wobei eine Abdichteinrichtung vorhanden ist, die den Sammelraum gegenüber der Niederdruckseite und der Hochdruckseite der Konstantpumpe abdichtet, und dass die Konstantpumpe einen mit dem Sammelraum verbundenen Leckageölauslass zum, insbesondere separaten, Abführen des Leckageöls aus der Konstantpumpe aufweist. Der Sammelraum weist somit keine unmittelbare Leitungsverbindung mehr zur Niederdruckseite der Konstantpumpe auf, sondern einen separaten Leckageölauslass. Damit wird bei der erfindungsgemäßen Konstantpumpe das Leckageöl nicht mehr direkt innerhalb der Pumpe dem Hydraulikkreislauf auf einer Saugseite zugeführt, sondern aus der Konstantpumpe über einen separaten Leckageölauslass, der den Sammelraum mit einer Leckageölsauslassöffnung der Konstantpumpe verbindet, abgeleitet. Darüber hinaus ist nicht nur die Hochdruckseite der Konstantpumpe gegenüber dem Sammelraum mithilfe der Abdichteinrichtung abgedichtet, sondern erfindungsgemäß ergänzend auch die Niederdruckseite, so dass das Hydraulikfluid auch von der Niederdruckseite nicht mehr in den Sammelraum drücken kann. Die Aufgabe des Sammelraums besteht darin, aus dem Achslager austretende Leckageanteile kontrolliert zu sammeln. Bevorzugt ist es dabei, wenn der Sammelraum derart ausgebildet ist, dass er das aus mehreren Achslagern austretende Leckageöl vereint und somit eine zentrale Abführung des Leckageöls aus der Konstantpumpe ermöglicht.An essential aspect of the invention is that the fixed displacement pump has a collecting space adjoining the axle bearing of the fixed displacement pump for the leakage portion of the hydraulic fluid emerging from the axle bearing, a sealing device being present which seals the collecting space from the low-pressure side and the high-pressure side of the fixed-displacement pump, and that the fixed displacement pump has a leakage oil outlet connected to the collecting space for, in particular separate, discharge of the leakage oil from the fixed displacement pump. The collecting space thus no longer has a direct line connection to the low-pressure side of the fixed displacement pump, but a separate leakage oil outlet. Thus, in the fixed displacement pump according to the invention, the leakage oil is no longer fed directly to the hydraulic circuit on a suction side within the pump, but is discharged from the fixed displacement pump via a separate leakage oil outlet that connects the collecting chamber with a leakage oil outlet opening of the fixed displacement pump. In addition, not only is the high-pressure side of the fixed displacement pump sealed off from the collecting chamber with the aid of the sealing device, but also the low-pressure side according to the invention so that the hydraulic fluid can no longer press into the collecting chamber from the low-pressure side either. The task of the collecting space is to collect leakage components from the axle bearing in a controlled manner. It is preferred here if the collecting space is designed in such a way that it combines the leakage oil emerging from a plurality of axle bearings and thus enables the leakage oil to be discharged centrally from the fixed displacement pump.
Es hat sich nun als vorteilhaft herausgestellt, wenn der Sammelraum als ein im Betrieb der Konstantpumpe zur Außenumgebung druckloser Sammelraum ausgebildet ist. Dies ermöglicht ein druckloses Abführen des im Sammelraum anfallenden Leckageöls aus der Pumpe. Im Sammelraum herrscht somit im Vergleich zur Außenumgebung der Konstantpumpe kein erhöhtes oder erniedrigtes Druckniveau, sondern der Druck der Außenumgebung.It has now been found to be advantageous if the collecting space is designed as a collecting space which is pressureless in relation to the outside environment when the fixed displacement pump is in operation. This enables the leakage oil that accumulates in the collecting space to be discharged from the pump without pressure. In comparison to the external environment of the fixed displacement pump, there is no increased or decreased pressure level in the collecting space, but rather the pressure of the external environment.
Hinsichtlich der konkreten Ausgestaltung des Sammelraums bestehen mannigfaltige vorteilhafte Weiterbildungsmöglichkeiten, die auch miteinander kombiniert werden können. So ist es beispielsweise bevorzugt, wenn sich der Sammelraum durch gegenüber dem Pumpengehäuse ortsfeste und/oder gegenüber der wenigstens einen Lagerachse ortsfeste Bauteile erstreckt. Ortsfest ist dabei so zu verstehen, dass die den Sammelraum begrenzenden Wände zumindest teilweise ihre Relativlage zum Pumpengehäuse oder zur Lagerachse im Betrieb der Konstantpumpe nicht ändern. Ein gegenüber dem Pumpengehäuse ortsfester Sammelraum kann insbesondere auch unmittelbar von einem Pumpengehäuseteil selbst ausgebildet sein. Ein gegenüber der Lagerachse ortsfestes Bauteil kann insbesondere auch unmittelbar von der Lagerachse selbst ausgebildet sein. Wesentlich für einen solchen Sammelraum ist somit, dass er sich mit der Lagerachse um die Rotationsachse mitdreht. Insbesondere kann der Sammelraum aber auch derart ausgebildet sein, dass er sich sowohl gegenüber dem Pumpengehäuse als auch gegenüber der Lagerachse ortsfeste Bereiche ausweist. In einer besonders bevorzugten konkreten Ausgestaltung des Sammelraums weist dieser einen die Lagerachse, insbesondere vollständig, umlaufenden Ringraum auf. Ergänzend oder alternativ kann er auch einen. sich in Axialrichtung der Lagerachse an eine Stirnseite der Lagerachse unmittelbar anschließenden Sammelkopfabschnitt umfassen, insbesondere derart, dass die Lagerachse und das Achslager stirnseitig bündig zum Sammelraum hin miteinander abschließen oder die Lagerachse in Axialrichtung etwas in den Sammelraum über das Achslager vorsteht. Besonders bevorzugt ist es ergänzend oder alternativ ferner, wenn der Sammelraum eine die Lagerachse in Axialrichtung von der einen zur anderen Stirnseite vollständig durchlaufende Sammeldurchgangsöffnung aufweist. Diese Anordnung kann insbesondere genutzt werden, um zwei relativ zum Pumpengehäuse ortsfeste Bereiche des Sammelraums miteinander zu verbinden. Weiter kann der Sammelraum auch ergänzend oder alternativ dahingehend ausgebildet sein, dass er wenigstens einen Verbindungskanal, der einen eine Lagerachse umlaufenden Ringraum oder einen Sammelkopfabschnitt oder eine Sammeldurchgangsöffnung mit einem eine Lagerachse umlaufenden Ringraum oder einem Sammelkopfabschnitt oder einer Sammeldurchgangsöffnung verbindet, aufweist. Ein solcher Verbindungskanal ist insbesondere ortsfest gegenüber dem Pumpengehäuse ausgebildet, beispielsweise als Verbindungsbohrung. Es ist ferner vorteilhaft, wenn der Sammelraum eine Sammelleitung umfasst, in die mehrere Verbindungskanäle münden. Über die Verbindungskanäle werden somit mehrere Leckageölströme zentral in der Sammelleitung vereint.With regard to the specific configuration of the collecting space, there are various advantageous further training options that can also be combined with one another. For example, it is preferred if the collecting space extends through components that are stationary relative to the pump housing and / or components that are stationary relative to the at least one bearing axis. Stationary is to be understood to mean that the walls delimiting the collecting space do not at least partially change their position relative to the pump housing or to the bearing axis during operation of the fixed displacement pump. A collecting space which is stationary with respect to the pump housing can in particular also be formed directly by a pump housing part itself. A component that is stationary with respect to the bearing axis can in particular also be formed directly from the bearing axis itself. It is therefore essential for such a collecting space that it rotates with the bearing axis about the axis of rotation. In particular, however, the collecting space can also be designed in such a way that it has fixed areas both with respect to the pump housing and with respect to the bearing axis. In a particularly preferred specific embodiment of the collecting space, it has a bearing axis, in particular completely, circumferential annular space. In addition or as an alternative, he can also use one. in the axial direction of the bearing axis directly adjoining the collecting head section on an end face of the bearing axis, in particular in such a way that the bearing axis and the axle bearing are flush with one another at the end face to the collecting space or the bearing axis protrudes somewhat in the axial direction into the collecting space over the axle bearing. In addition or as an alternative, it is particularly preferred if the collecting space has a collecting passage opening which runs completely through the bearing axis in the axial direction from one to the other end face. This arrangement can in particular be used to connect two areas of the collecting space that are stationary relative to the pump housing. Furthermore, the collecting space can additionally or alternatively be designed in such a way that it has at least one connecting channel which connects an annular space surrounding a bearing axis or a collecting head section or a collecting passage opening with an annular space surrounding a bearing axis or a collecting head section or a collecting passage opening. Such a connection channel is designed in particular to be stationary with respect to the pump housing, for example as a connection bore. It is also advantageous if the collecting space comprises a collecting line into which several connecting channels open. Several leakage oil flows are thus combined centrally in the collecting line via the connecting channels.
Es besteht nun die bevorzugte Möglichkeit, den Sammelraum teilweise in mehreren Bauteilen und/oder über mehrere Bauteile hinweg und/oder in mehreren Bereichen der Konstantpumpe auszubilden. Der Sammelraum erstreckt sich hier somit in und/oder über mehrere Bauteile hinweg. Besonders geeignet ist hierzu beispielsweise eine Ausbildung des Sammelraums oder zumindest eines Teilbereiches desselben in der Lagerachse, insbesondere derart, dass er die Lagerachse in Axialrichtung, insbesondere vollständig, durchläuft. Der Sammelraum kann ergänzend oder alternativ auch, insbesondere direkt, im Fördermittel ausgebildet sein, insbesondere ebenfalls derart, dass er die Lagerachse in Axialrichtung der Rotationsachse, insbesondere vollständig, durchläuft. Eine weitere bevorzugte Möglichkeit besteht darin, den Sammelraum zumindest teilweise in einer Lagerbrille, in der wenigstens eine Lagerachse gelagert ist, auszubilden. Eine solche, insbesondere einstückig ausgebildete, Lagerbrille kann insbesondere dazu vorgesehen sein, gleichzeitig zwei parallel zueinander verlaufende Lagerachsen einer Konstantpumpe zu lagern, beispielsweise als Verbindungsteil zwischen zwei Pumpeneinheiten einer als Tandempumpe ausgebildeten Konstantpumpe. Grundsätzlich ist es aber auch möglich, eine solche Lagerbrille mehrteilig auszubilden. Weiter ergänzend oder alternativ kann der Sammelraum beispielsweise auch in einem Pumpenflansch bzw. einer Pumpenflanschplatte, insbesondere als Oberflächenausnehmung auf der einer Anflanschseite gegenüberliegenden Seite, ausgebildet sein. Weiter ergänzend oder alternativ kann es auch vorgesehen sein, dass der Sammelraum in einem Pumpendeckel, insbesondere als Oberflächenausnehmung auf der einer Außenseite des Pumpendeckels gegenüberliegenden Seite, ausgebildet ist. Ein weiteres, ebenfalls bevorzugtes Bauteil zur Ausbildung des Sammelraums ist ergänzend oder alternativ eine Kopplungsplatte einer Tandempumpe. Eine solche Kopplungsplatte dient dazu, zwei Konstantpumpeneinheiten miteinander mechanisch in einer an sich im Stand der Technik bekannten Tandemanordnung zu koppeln. Von der Bauart her kann eine solche Kopplungsplatte beispielsweise als eine Platte mit zwei oder mehreren einander gegenüberliegenden Ausnehmungen und/oder Durchgangsöffnungen zur Aufnahme wenigstens einer Lagerachse jeder Konstantpumpeneinheit ausgebildet sein, wodurch eine vergleichsweise kompakte Tandemanordnung möglich wird, oder zumindest mit einer Durchführöffnung für ein Kopplungselement zu Antriebszwecken zwischen den beiden Konstantpumpeneinheiten.There is now the preferred possibility of partially forming the collecting space in several components and / or over several components and / or in several areas of the fixed displacement pump. The collecting space thus extends here in and / or over several components. Particularly suitable for this purpose is, for example, a design of the collecting space or at least a partial area thereof in the bearing axis, in particular such that it passes through the bearing axis in the axial direction, in particular completely. The collecting space can additionally or alternatively also, in particular directly, be formed in the conveying means, in particular likewise in such a way that it passes through the bearing axis, in particular completely, in the axial direction of the axis of rotation. Another preferred possibility consists in forming the collecting space at least partially in a bearing bracket in which at least one bearing axis is mounted. Such a, in particular one-piece, bearing bracket can be provided in particular to mount two parallel bearing axles of a constant displacement pump at the same time, for example as a connecting part between two pump units of a constant displacement pump designed as a tandem pump. In principle, however, it is also possible to design such a bearing bracket in several parts. Additionally or alternatively, the collecting space can also be designed, for example, in a pump flange or a pump flange plate, in particular as a surface recess on the side opposite a flange side. In addition or as an alternative, it can also be provided that the collecting space is formed in a pump cover, in particular as a surface recess on the side opposite an outside of the pump cover. Another, likewise preferred component for forming the collecting space is, in addition or as an alternative, a coupling plate of a tandem pump. Such a coupling plate is used to mechanically couple two constant pump units to one another in a tandem arrangement known per se in the prior art. From the design, such a coupling plate can, for example, as a plate with two or several opposing recesses and / or through openings for receiving at least one bearing axis of each constant pump unit, which enables a comparatively compact tandem arrangement, or at least with a feed-through opening for a coupling element for drive purposes between the two constant pump units.
Auch hinsichtlich der konkreten Ausgestaltung der Abdichteinrichtung bestehen bevorzugte Variationsmöglichkeiten. Diese ist beispielsweise bevorzugt als Berührungsdichtung, insbesondere zwischen einem Pumpendeckel und einem, insbesondere den radialen Förderraum zur Rotationsachse des wenigstens einen Förderelementes bildenden, Gehäuseteil angeordnet. Die Abdichteinrichtung besteht bevorzugt aus einem elastischen Material. Vom Material her kann es sich bei der Abdichteinrichtung insbesondere um ein Polymermaterial, insbesondere ein Kunststoffpolymer, beispielsweise NBR (Nitril-Kautschuk, Fluor-Kautschuk etc. handeln. Bevorzugt sind Elastomere oder Thermoplaste. Auch die Verwendung metallischer Dichtungen ist möglich. Auch beschichtete Dichtungen können als Abdichteinrichtung verwendet werden. Besonders bevorzugt ist die Ausbildung der Abdichteinrichtung als Flachdichtung, d.h. in einer Bauform, bei der die Höhe der Dichtung klein ist gegenüber der Dichtfläche und die sich insbesondere mit ihrer gesamten Breite ihrer Dichtfläche an die anliegenden Dichtflächen anpasst. Die Abdichteinrichtung kann bevorzugt alternativ beispielsweise auch als Formdichtung, insbesondere mit eher quadratischem Querschnitt mit abgerundeten Kanten, ausgebildet sein. Die Abdichteinrichtung kann aus mehreren separaten Untereinheiten bestehen. Es kann allerdings, beispielsweise zur Erleichterung der Montage, vorteilhaft sein, wenn die Abdichteinrichtung als Ganzes einstückig ausgebildet ist. Die für die Abdichtung des Sammelraums gegenüber gleichzeitig der Nieder- und der Hochdruckseite der Konstantpumpe verwendete Abdichteinrichtung besteht dann aus einem einzigen, zusammenhängenden Teil. Weiter kann es auch möglich sein, dass die Abdichteinrichtung aus mehreren Untereinheiten, dann aber bevorzugt zueinander baugleichen Untereinheiten, aufgebaut ist. Ergänzend oder alternativ kann es vorgesehen sein, dass sie wenigstens einen die Lagerachse bzw. die Rotationsachse des Förderelementes radial vollständig umlaufenden Dichtabschnitt aufweist. Insbesondere für den Fall, dass die Konstantpumpe mehr als ein Förderelement umfasst, ist die Abdichteinrichtung bevorzugt in der Weise ausgebildet, dass sie zwei jeweils eine Lagerachse radial vollständig umlaufende Dichtabschnitte sowie einen Verbindungsabschnitt, der die beiden Dichtabschnitte miteinander verbindet, umfasst. Dazu kann die Abdichteinrichtung insbesondere in Form einer Abdichtbrille ausgebildet sein. Die Abdichteinrichtung kann insbesondere wenigstens zwei Abdichtelemente umfassen, die in Axialrichtung der Rotationsachse eines Förderelementes hintereinander, insbesondere zueinander deckungsgleich, angeordnet sind. Die Abdichteinrichtung wird ferner bevorzugt in Axialrichtung der Rotationsachse mit einer Spannkraft beaufschlagt.There are also preferred possible variations with regard to the specific design of the sealing device. This is, for example, preferably arranged as a contact seal, in particular between a pump cover and a housing part that forms, in particular, the radial conveying space relative to the axis of rotation of the at least one conveying element. The sealing device is preferably made of an elastic material. In terms of material, the sealing device can in particular be a polymer material, in particular a plastic polymer, for example NBR (nitrile rubber, fluorine rubber, etc. Elastomers or thermoplastics are preferred. Metallic seals can also be used. Coated seals can also be used It is particularly preferred to design the sealing device as a flat seal, ie in a design in which the height of the seal is small compared to the sealing surface and which, in particular, adapts to the adjacent sealing surfaces with its entire width of its sealing surface preferably alternatively, for example, also be designed as a molded seal, in particular with a more square cross-section with rounded edges. The sealing device can consist of several separate subunits. However, it can be advantageous, for example to facilitate assembly, if the sealing device is designed in one piece as a whole. The sealing device used to seal the collecting space from the low and high pressure sides of the fixed displacement pump at the same time then consists of a single, coherent part. Furthermore, it can also be possible for the sealing device to be constructed from a plurality of subunits, but then preferably subunits which are structurally identical to one another. In addition or as an alternative, it can be provided that it has at least one sealing section that completely encircles the bearing axis or the axis of rotation of the conveying element. In particular, in the event that the fixed displacement pump comprises more than one delivery element, the sealing device is preferably designed in such a way that it comprises two sealing sections, each completely encircling a bearing axis, and a connecting section that connects the two sealing sections to one another. For this purpose, the sealing device can in particular be designed in the form of a sealing goggle. The sealing device can in particular comprise at least two sealing elements which are arranged one behind the other, in particular congruent with one another, in the axial direction of the axis of rotation of a conveying element. The sealing device is also preferably acted upon with a tension force in the axial direction of the axis of rotation.
Hinsichtlich der konkreten Ausgestaltung der Konstantpumpe sind ebenfalls bevorzugte Weiterbildungen möglich. So handelt es sich bei der Konstantpumpe bevorzugt um eine Außenzahnradpumpe, umfassend zwei nebeneinander liegende, miteinander kämmende und um jeweils eine Rotationsachse drehende Zahnräder mit jeweils außenliegender Verzahnung, zwei parallel zueinander verlaufende, in Axialrichtung der Rotationsachsen zumindest teilweise auf gleicher Höhe angeordnete Lagerachsen, wobei die eine Lagerachse das eine Zahnrad und die andere Lagerachse das andere Zahn trägt. Es ist vorteilhaft, wenn die eine der Lagerachsen als eine aus dem Gehäuse vorspringende Antriebsachse ausgebildet ist, umfassend eine Formschlusseinrichtung zum Eingriff einer Antriebsanordnung, insbesondere eine Passverzahnung. Dies ermöglicht den Anschluss eines Antriebsstrangs. Ergänzend oder alternativ umfasst nur eine der Lagerachsen, insbesondere die von der anderen Lagerachse angetriebene Lagerachse, eine sich in Axialrichtung durch die Lagerachse vollständig erstreckende und zu beiden Stirnseiten offene Durchgangsöffnung als Teil des Sammelraums. Die mit dem extern zur Konstantpumpe angeordneten Antriebsstrang in Verbindung stehende Lagerachse ist dagegen bevorzugt im Wesentlichen massiv ausgebildet.With regard to the specific design of the fixed displacement pump, preferred developments are also possible. The fixed displacement pump is preferably an external gear pump, comprising two juxtaposed, intermeshing gearwheels each rotating around an axis of rotation, each with external toothing, two parallel to one another, at least partially at the same height in the axial direction of the axes of rotation Bearing axles, one bearing axle carrying one gear and the other bearing axle carrying the other tooth. It is advantageous if one of the bearing axles is designed as a drive axle protruding from the housing, comprising a form-fit device for engaging a drive arrangement, in particular a spline. This enables the connection of a drive train. In addition or as an alternative, only one of the bearing axles, in particular the bearing axle driven by the other bearing axle, comprises a through opening that extends completely through the bearing axle in the axial direction and is open on both end faces as part of the collecting space. The bearing axis connected to the drive train arranged externally to the fixed displacement pump, on the other hand, is preferably designed to be essentially solid.
Insbesondere für Baumaschinen ist es bekannt und üblich, dass diese gleichzeitig mehrere, funktional getrennte, anzutreibende Hydraulikkomponenten aufweisen können, wie beispielsweise insbesondere für Straßenfertiger und Beschicker. Es ist daher auch bevorzugt, wenn die Konstantpumpe als Tandempumpe mit einer ersten und einer zweiten Konstantpumpeneinheit ausgebildet ist. Auf diese Weise können gleichzeitig mehrere, zueinander separate Hydraulikkreisläufe über einen die Konstantpumpe mit den mehreren Konstantpumpeneinheiten antreibenden Antriebsstrang betrieben werden. Die Tandempumpe weist hierzu erfindungsgemäß bevorzugt eine Kopplungsplatte auf, die unmittelbar zwischen zwei Zahnradpaarungen der ersten und der zweiten Konstantpumpeneinheit angeordnet ist. Es ist nun vorgesehen, dass ein Teil des Sammelraums der Konstantpumpe durch die Kopplungsplatte gebildet wird und/oder in Richtung der Rotationsachse der Zahnradpaarungen beidseits der Kopplungsplatte jeweils eine Dichtung als Teil der Abdichteinrichtung vorhanden ist. Ergänzend oder alternativ kann es vorgesehen sein, dass mehrere der Lagerachsen diese vollständig durchlaufende Durchgangsöffnungen als Teil des Sammelraums aufweisen. Dies erleichtert es, einen gemeinsamen, durchgängigen Sammelraum für sämtliche der Konstantpumpeneinheiten der Konstantpumpe zu erhalten. Weiter ergänzend oder alternativ umfasst eine solche Konstantpumpe mit mehreren Konstantpumpeneinheiten, insbesondere ausschließlich, einen einzigen gemeinsamen Leckageölauslass. Damit wird das Leckageöl der wenigstens zwei Konstantpumpeneinheiten somit in einen zusammengehörigen Sammelraum abgeführt und über den einzigen, gemeinsamen Leckageölauslass aus der Konstantpumpe abgeleitet. Dabei ist es besonders bevorzugt, wenn der Leckageölauslass in einem Pumpendeckel, insbesondere einem Pumpendeckel nur einer der wenigstens zwei Konstantpumpeneinheiten, angeordnet ist. Ergänzend oder alternativ kann es bevorzugt vorgesehen sein, dass der Leckageölauslass in einem Flansch angeordnet ist.For construction machinery in particular, it is known and customary that these can have several functionally separate hydraulic components to be driven at the same time, such as, for example, in particular for road pavers and feeders. It is therefore also preferred if the fixed displacement pump is designed as a tandem pump with a first and a second fixed displacement pump unit. In this way, several hydraulic circuits that are separate from one another can be operated simultaneously via a drive train that drives the fixed displacement pump with the several fixed displacement pump units. For this purpose, the tandem pump preferably has a coupling plate, according to the invention, which is arranged directly between two gear wheel pairs of the first and the second constant pump unit. It is now provided that part of the collecting space of the fixed displacement pump is formed by the coupling plate and / or a seal is present as part of the sealing device on both sides of the coupling plate in the direction of the axis of rotation of the gear pairs. In addition or as an alternative, it can be provided that several of the bearing axles have through openings running through them as part of the collecting space. This makes it easier to obtain a common, continuous collecting space for all of the fixed displacement pump units of the fixed displacement pump. Additionally or alternatively, such a fixed displacement pump with a plurality of fixed displacement pump units, in particular exclusively, comprises a single common leakage oil outlet. The leakage oil of the at least two fixed displacement pump units is thus discharged into an associated collecting space and discharged from the fixed displacement pump via the single, common leakage oil outlet. It is particularly preferred if the leakage oil outlet is arranged in a pump cover, in particular a pump cover of only one of the at least two constant pump units. In addition or as an alternative, it can preferably be provided that the leakage oil outlet is arranged in a flange.
Eine weitere wesentliche Weiterbildung der Erfindung kann darin bestehen, dass die Konstantpumpe eine Ventileinrichtung umfasst, die an den Fluidpumpeneingang und den Fluidpumpenausgang angeschlossen und/oder dem Fluidpumpeneingang und dem Fluidpumpenausgang vorgeschaltet ist. Mithilfe einer solchen Ventileinrichtung können für die insbesondere in einem geschlossenen Kreislauf betriebene Konstantpumpe Funktionalitäten imitiert werden, die konventionell nur beispielsweise mit einer Verstellpumpe mit variablen Fördervolumen möglich sind, wie beispielsweise eine Umkehr der Durchflussrichtung in zumindest einem Teil des geschlossenen Hydraulikkreislaufes und/oder eine Verstellung des in zumindest einem Teil des geschlossenen Hydraulikreislaufes geförderten Hydraulikfluidvolumens pro Umdrehung der Konstantpumpe. Eine bevorzugte Ventilfunktion der Ventileinrichtung ist "Schalten zwischen einer direkten und geschlossenen Umleitung vom Fluidpumpeneingang zum Fluidpumpenausgang und eine Unterbrechung der geschlossenen Umleitung". Wird das Hydraulikfluid direkt vom Fluidpumpenausgang zum Fluidpumpeneingang geleitet, passiert das von der Konstantpumpe geförderte Hydraulikfluid im geschlossenen Kreislauf keinen hydraulischen Verbraucher. Die Konstantpumpe fördert bei dieser Ventilfunktion somit Hydraulikfluid in einem verkürzten geschlossenen Hydraulikkreislauf unter Umgehung wenigstens eines hydraulischen Verbrauchers, wie beispielsweise einem Hydromotor, vom Fluidpumpenausgang über die Ventileinrichtung direkt wieder zurück zum Fluidpumpeneingang. Entsprechend ist der hydraulische Verbraucher dann inaktiv. Wird die geschlossene direkte Umleitung über die Ventileinrichtung vom Fluidpumpenausgang zum Fluidpumpeneingang aktiviert, wird somit kein Hydraulikfluid im geschlossenen Hydraulikkreislauf bis hin zum hydraulischen Verbraucher gefördert. Ergänzend oder alternativ kann die Ventileinrichtung auch derart ausgebildet sein, dass sie ein Umschalten einer Fluidverbindung zwischen dem Fluidpumpenausgang und einem ersten Ausgang der Ventileinrichtung zu einer Fluidverbindung zwischen dem Fluidpumpenausgang und einem zweiten Ausgang der Ventileinrichtung ermöglicht. Über diese Schaltkonstellation kann beispielsweise erreicht werden, dass eine Umkehrung der Förderrichtung in demjenigen Teil des geschlossenen Hydraulikkreislaufes erreicht wird, der zwischen der Ventileinrichtung und dem hydraulischen Verbraucher, wie beispielsweise einem Hydromotor, erfolgt. Die Ventileinrichtung kann ergänzend oder alternativ auch derart ausgebildet sein, dass sie ein Aufteilen des von der Konstantpumpe geförderten Hydraulikvolumens in zwei Teilströme, konkret einen direkt zur Konstantpumpe zurückgeführten Teilstrom und einen um hydraulischen Verbraucher weitergeleiteten Teilstrom ermöglicht. Auf diese Weise kann der Anteil des zum hydraulischen Verbraucher weitergeleiteten Hydraulikfluidvolumens auch bei konstantem Fördervolumen der Konstantpumpe im Sinne einer Verstellpumpe variiert werden. Darüber hinaus kann die Ventileinrichtung auch derart ausgebildet sein, dass eine Druckabsicherung einer Hochdruckseite der Konstantpumpe und/oder ein Freigeben einer Ablassleitung bei Überschreiten einer Druckschwelle auf der Hochdruckseite erfolgt. Dazu kann die Ventileinrichtung beispielsweise ein, bevorzugt einstellbares, Druckbegrenzungsventil umfassen. Besonders bevorzugt ist es schließlich weiter ergänzend oder alternativ, wenn die Ventileinrichtung derart ausgebildet ist, dass sie ein Herstellen einer druckabgesicherten Fluidverbindung von einer Speiseleitung zu einem Niederdruckbereich der Konstantpumpe ermöglicht. Eine solche Anordnung dient insbesondere zum Ausgleich von Leckageölverlusten und/oder wärmebedingten Ölverlusten im geschlossenen Hydraulikkreislauf, um ein gewünschtes Fluidvolumen im geschlossenen Hydraulikkreislauf und damit ein gewünschtes Druckniveau, insbesondere auch auf der Niederdruckseite des geschlossenen Hydraulikkreislaufes, zu ermöglichen. Dazu kann die Speiseleitung beispielsweise von einer geeigneten Speisepumpe mit Hydraulikfluid gespeist werden. Die Speiseleitung ist über eine geeignete Druckabsicherung, beispielsweise ein, insbesondere einstellbares, Druckbegrenzungsventil an den geschlossenen Hydraulikkreislauf, zur Nieder- und oder zur Hochdruckseite hin, angeschlossen. Die Speisepumpe stellt bevorzugt eine zur erfindungsgemäßen Konstantpumpe separate Einheit dar. In einer weiteren bevorzugten Alternative kann die Speisepumpe aber auch als zusätzliche Stufe in die erfindungsgemäße Konstantpumpe integriert sein.A further essential development of the invention can consist in the fact that the fixed displacement pump comprises a valve device which is connected to the fluid pump inlet and the fluid pump outlet and / or is connected upstream of the fluid pump inlet and the fluid pump outlet. With the help of such a valve device, functionalities can be imitated for the constant pump, which is operated in a closed circuit in particular, which are conventionally only possible, for example, with a variable displacement pump with variable delivery volume, such as a reversal of the flow direction in at least part of the closed hydraulic circuit and / or an adjustment of the Hydraulic fluid volume conveyed in at least part of the closed hydraulic circuit per revolution of the fixed displacement pump. A preferred valve function of the valve device is "switching between a direct and closed bypass from the fluid pump inlet to the fluid pump outlet and an interruption of the closed bypass". If the hydraulic fluid is fed directly from the fluid pump outlet to the fluid pump inlet, the hydraulic fluid delivered by the fixed displacement pump does not pass any hydraulic consumers in the closed circuit. With this valve function, the fixed displacement pump thus conveys hydraulic fluid in a shortened, closed hydraulic circuit, bypassing at least one hydraulic consumer, such as a hydraulic motor, from the fluid pump outlet via the valve device directly back to the fluid pump inlet. The hydraulic consumer is then inactive accordingly. If the closed direct diversion via the valve device from the fluid pump outlet to the fluid pump inlet is activated, no hydraulic fluid is conveyed in the closed hydraulic circuit to the hydraulic consumer. Additionally or alternatively, the valve device can also be designed such that it enables a fluid connection between the fluid pump outlet and a first outlet of the valve device to be switched to a fluid connection between the fluid pump outlet and a second outlet of the valve device. This switching constellation can be used, for example, to reverse the conveying direction in that part of the closed hydraulic circuit that takes place between the valve device and the hydraulic consumer, such as a hydraulic motor. The valve device can additionally or alternatively also be designed in such a way that it enables the hydraulic volume delivered by the fixed displacement pump to be divided into two partial flows, specifically a partial flow returned directly to the fixed displacement pump and a partial flow passed on to the hydraulic consumer. In this way, the proportion of the hydraulic fluid volume passed on to the hydraulic consumer can be varied in the sense of a variable displacement pump even with a constant delivery volume of the fixed displacement pump. In addition, the valve device can also be designed in such a way that a high-pressure side of the fixed displacement pump is pressure-protected and / or a discharge line is released when a pressure threshold is exceeded on the high-pressure side. For this purpose, the valve device can comprise, for example, a preferably adjustable pressure limiting valve. Finally, it is particularly preferred, additionally or alternatively, if the valve device is designed in such a way that it enables a pressure-protected fluid connection to be established from a feed line to a low-pressure region of the fixed displacement pump. Such an arrangement serves in particular to compensate for leakage oil losses and / or heat-related oil losses in the closed hydraulic circuit in order to enable a desired fluid volume in the closed hydraulic circuit and thus a desired pressure level, in particular also on the low-pressure side of the closed hydraulic circuit. For this purpose, the feed line can be fed with hydraulic fluid, for example, from a suitable feed pump. The feed line is connected to the closed hydraulic circuit, to the low and / or the high pressure side, via a suitable pressure protection device, for example an, in particular adjustable, pressure limiting valve. The feed pump is preferably a unit separate from the constant pump according to the invention. In a further preferred alternative, the feed pump can also be integrated into the constant pump according to the invention as an additional stage.
Von der konkret baulichen Konzeption her bestehen ebenfalls mannigfaltige Möglichkeiten zur vorteilhaften Ausbildung der Ventileinrichtung. Insbesondere kann es vorgesehen sein, dass die Ventileinrichtung als modulare Einheit mit einem Grundventilblock und einem oder mehreren Funktionsventilblöcken ausgebildet ist. Der Grundventilblock kann beispielsweise eine Anschlussöffnung zur Verbindung mit dem Fluidpumpeneinlass bzw. einer Leitung zum Fluidpumpeneinlass der Konstantpumpe, und/oder eine Anschlussöffnung zur Verbindung mit dem Fluidpumpenauslass bzw. einer Leitung zum Fluidpumpenauslass der Konstantpumpe, und/oder eine Anschlussöffnung zur Verbindung mit einem Motoreinlass bzw. einer Leitung zum Einlass eines Motors, insbesondere Hydromotors, und/oder eine Anschlussöffnung zur Verbindung mit einem Motorauslass bzw. einer Leitung zum Auslass eines Motors, insbesondere Hydromotors umfassen. Ergänzend kann der Grundventilblock eine Anschlussöffnung zur Verbindung an eine Speiseleitung umfassen. Über diesen Anschluss ist es somit möglich, Hydraulikfluid in den geschlossenen Hydraulikkreislauf von extern, beispielsweise mithilfe einer Speisepumpe, einzuspeisen. Ergänzend oder alternativ kann der Grundventilblock eine Leitungsunterbrechung mit einer Unterbrechungsausgangsöffnung und einer Unterbrechungseingangsöffnung aufweisen. Dabei stehen die Unterbrechungsausgangsöffnung und die Unterbrechungseingangsöffnung im Grundventilblock selbst nicht in Fluidverbindung miteinander, können aber in der nachstehend beschriebenen Weise mithilfe eines geeigneten Funktionsmodulblockes in Fluidverbindung miteinander gebracht werden.In terms of the specific structural concept, there are also diverse possibilities for an advantageous design of the valve device. In particular, it can be provided that the valve device is designed as a modular unit with a basic valve block and one or more functional valve blocks. The basic valve block can, for example, have a connection opening for connection to the fluid pump inlet or a line to the fluid pump inlet of the fixed displacement pump, and / or a connection opening for connection to the fluid pump outlet or a line to the fluid pump outlet of the fixed displacement pump, and / or a connection opening for connection to a motor inlet or a line for the inlet of a motor, in particular a hydraulic motor, and / or a connection opening for connection to an engine outlet or a line for the outlet of a motor, in particular a hydraulic motor. In addition, the basic valve block can include a connection opening for connection to a feed line. This connection makes it possible to feed hydraulic fluid into the closed hydraulic circuit from the outside, for example with the aid of a feed pump. Additionally or alternatively, the basic valve block can have a line interruption with an interruption outlet opening and an interruption inlet opening. The interruption outlet opening and the interruption inlet opening in the basic valve block itself are not in fluid connection with each other, but can be brought into fluid connection with each other in the manner described below with the aid of a suitable functional module block.
Zum Erhalt verschiedener Funktionalitäten ist es bevorzugt, wenn ergänzend zum Grundventilblock ein oder mehrere Funktionsventilblöcke vorhanden sind. Über einen Funktionsventilblock kann eine oder können mehrere Betriebsfunktionen am Grundventilblock erhalten werden. Die Ausbildung als separaten und austauschbar am Grundventilblock angeordneten Funktionsmodulblock ermöglicht dabei eine individuelle Anpassung der konkreten Funktionen der Ventileinrichtung. Der Funktionsmodulblock weist dazu eine Modulblockeingangsöffnung und eine über eine Ventileinrichtung und/oder eine Leitungsverbindung mit der Modulblockeingangsöffnung in fluidleitender Verbindung stehende Modulblockausgangsöffnung auf. Das Hydraulikfluid passiert den Funktionsmodulblock somit von der Eingangsöffnung kommend zur Ausgangsöffnung hin. Der Funktionsmodulblock kann beispielsweise, insbesondere austauschbar, am Grundventilblock derart befestigt sein, dass die Unterbrechungsausgangsöffnung in Fluidverbindung mit der Modulblockeingangsöffnung und die Modulblockausgangsöffnung in Fluidverbindung mit der Unterbrechungseingangsöffnung steht. Mit dieser Anordnung wird das Hydraulikfluid, insbesondere im geschlossenen Hydraulikkreislauf von der Konstantpumpe kommend, aus dem Grundventilblock in den Funktionsmodulblock und von diesem wieder zurück zum Grundventilblock geleitet, bevor es einem hydraulischen Verbraucher, beispielsweise einem Hydromotor, zugeführt wird. Der Grundventilblock stellt somit eine Art von der Konstantpumpe mit Hydraulikfluid in einem geschlossenen System versorgten Adapter dar, an den verschiedene Funktionen verwirklicht werden können. Dazu wird wenigstens ein Funktionsmodulblock an den Grundventilblock angeschlossen. Der Funktionsmodulblock kann entsprechend reine Durchgangsleitungen für das Hydraulikfluid und/oder, insbesondere schaltbare Schalteinrichtungen, insbesondere wenigstens ein Ventil, ganz besonders wenigstens ein 2/2-Wege-Ventil und/oder wenigstens ein 4/2-Wege-Ventil, und/oder einen, insbesondere stufenlos veränderbaren, Strömungsteiler, konkret ein variables, insbesondere proportional steuerbares, Stromregelventil, aufweisen.In order to obtain various functionalities, it is preferred if one or more functional valve blocks are present in addition to the basic valve block. One or more operating functions can be obtained on the basic valve block via a function valve block. The design as a separate and interchangeable function module block arranged on the basic valve block enables individual adaptation of the specific functions of the valve device. For this purpose, the functional module block has a module block inlet opening and a module block outlet opening which is in fluid-conducting connection with the module block inlet opening via a valve device and / or a line connection. The hydraulic fluid thus passes through the functional module block from the inlet opening to the outlet opening. The functional module block can, for example, in particular be exchangeably attached to the basic valve block in such a way that the interruption outlet opening is in fluid connection with the module block inlet opening and the module block outlet opening is in fluid connection with the interruption inlet opening. With this arrangement, the hydraulic fluid, especially coming from the fixed displacement pump in the closed hydraulic circuit, is passed from the basic valve block into the functional module block and from there back to the basic valve block before it is fed to a hydraulic consumer, for example a hydraulic motor. The basic valve block thus represents a type of adapter that is supplied with hydraulic fluid in a closed system by the fixed displacement pump and on which various functions can be implemented. For this purpose, at least one functional module block is connected to the basic valve block. The functional module block can correspondingly pure through lines for the hydraulic fluid and / or, in particular, switchable switching devices, in particular at least one valve, very particularly at least one 2/2-way valve and / or at least a 4/2-way valve and / or a, in particular continuously variable, flow divider, specifically a variable, in particular proportionally controllable, flow control valve.
Konkret kann es beispielsweise vorgesehen sein, dass der Funktionsmodulblock derart ausgebildet ist, er ein Umschalten zwischen zwei Einlass- und zwei Auslassöffnungen ermöglicht, insbesondere beispielsweise über ein schaltbares 4/2-Wege-Ventil. Bei dieser Funktion kann ein durch den Funktionsmodulblock geführter geschlossener Hydraulikreislauf zu einem Verbraucher hin bezüglich seiner Durchströmungsrichtung umgekehrt werden. Ergänzend oder alternativ kann der Funktionsmodulblock auch als Durchleitungsbrücke ausgebildet sein und damit ein statisches Durchleiten von festgelegten Eingängen zu festgelegten Ausgängen ermöglichen. Weiter ergänzend oder alternativ kann der Funktionsmodulblock auch derart ausgebildet sein, dass über ihn ein An- und Ausschalten einer Speisefunktion möglich ist, über die Hydraulikfluid von außen in den geschlossenen Hydraulickreislauf eingespeist wird. Weiter ergänzend oder alternativ kann es ferner vorgesehen sein, dass der Funktionsmodulblock einen eingehenden Hydraulikvolumenstrom in zwei ausgehende Hydraulikvolumenströme aufteilt, beispielsweise mithilfe eines Stromregelventils. Auf diese Weise kann beispielsweise der Volumenstromanteil, der in Durchströmungsrichtung zu einem hydraulischen Verbraucher weitergeleitet wird, und der Volumenstromanteil, der beispielsweise unter Umgehung zur Pumpe zurückgeleitet wird, variiert werden. Eine weitere mithilfe eines Funktionsmodulblockes dargestellte Weiterbildung kann auch ein Speisedruck-Bypass sein, der speziell für die Kaltstartphase hilfreich ist. Mithilfe des Speisedruck-Bypass kann Hydraulikfluid unter Umgehung des Verbrauchers direkt zur Konstantpumpe umgeleitet werden. Das Hydraulikfluid wird im geschlossenen Hydraulickreis somit nur in einem Teilsegment zirkuliert und kann sich auf dieses Weise schneller erwärmen. Erst wenn der Speisedruck-Bypass gesperrt wird, fördert die Konstantpumpe in den in Förderrichtung stromabwärts zur Konstantpumpe zum Verbraucher hin gelegenen Leitungsteil. Eine solche Funktionalität kann mit einer geeigneten Bypass-Leitung, beispielsweise auch im Grundmodulblock, und einem geeigneten Ventil, insbesondere im Funktionsmodulblock, vorgesehen sein. Wesentlich für die Bypass-Leitung ist, dass sie eine Rückführung der von der Konstantpumpe geförderten Hydraulikfluids von der Hochdruckseite zur Niederdruckseite unter Umgehung des Verbrauchers ermöglicht.Specifically, it can be provided, for example, that the functional module block is designed in such a way that it enables switching between two inlet and two outlet openings, in particular for example via a switchable 4/2-way valve. With this function, a closed hydraulic circuit routed through the function module block to a consumer can be reversed with regard to its flow direction. In addition or as an alternative, the function module block can also be designed as a feed-through bridge and thus enable a static feed-through of defined inputs to defined outputs. In addition or as an alternative, the function module block can also be designed in such a way that it can be used to switch a feed function on and off, via which hydraulic fluid is fed from the outside into the closed hydraulic circuit. In addition or as an alternative, it can also be provided that the function module block divides an incoming hydraulic volume flow into two outgoing hydraulic volume flows, for example with the aid of a flow control valve. In this way, it is possible, for example, to vary the volume flow component that is passed on in the flow direction to a hydraulic consumer, and the volume flow component that is passed back to the pump, for example bypassing. A further development shown with the aid of a function module block can also be a feed pressure bypass, which is particularly helpful for the cold start phase. With the aid of the feed pressure bypass, hydraulic fluid can be diverted directly to the fixed displacement pump, bypassing the consumer. The hydraulic fluid is therefore only circulated in a partial segment in the closed hydraulic circuit and can heat up more quickly in this way. Only when the feed pressure bypass is blocked does the fixed displacement pump deliver in the line part located downstream in the conveying direction from the fixed displacement pump to the consumer. Such a functionality can be provided with a suitable bypass line, for example also in the basic module block, and a suitable valve, in particular in the functional module block. It is essential for the bypass line that it enables the hydraulic fluid delivered by the fixed displacement pump to be returned from the high pressure side to the low pressure side, bypassing the consumer.
Hinsichtlich der konkreten Auslegung des Grundventilblockes bestehen ebenfalls Variationsmöglichkeiten. So ist es beispielsweise bevorzugt, wenn der Grundventilblock zum gleichzeitigen Anschluss wenigstens zweier Funktionsmodulblöcke ausgebildet ist. Die angeschlossenen Funktionsmodulblöcke verwirklichen dabei bevorzugt verschiedene Funktionalitäten. Grundsätzlich werden die beiden Funktionsmodulblöcke idealerweise derart ausgebildet, dass sie zur Durchführung wenigstens einer der Funktionalitäten "An/Aus-Funktion" und/oder "Richtungsumkehr" und/oder "Strömungsteiler" bzw. "Stromregeln" an einem angeschlossenen Verbraucher, ganz besonders Hydromotor, ausgebildet sind, wobei sich die jeweilige Funktionalität dabei auf das Verhalten des angeschlossenen und vom geschlossenen Hydraulikkreislauf angetriebenen Verbraucher bezieht.With regard to the specific design of the basic valve block, there are also possible variations. For example, it is preferred if the basic valve block is designed for the simultaneous connection of at least two functional module blocks. The connected function module blocks preferably implement different functionalities. Basically, the two function module blocks are ideally designed in such a way that they can perform at least one of the functionalities "on / off function" and / or "direction reversal" and / or "flow divider" or "flow control" on a connected consumer, especially hydraulic motor, are designed, the respective functionality being related to the behavior of the connected consumer driven by the closed hydraulic circuit.
Die Ventileinrichtung, insbesondere der Grundventilblock, ist unabhängig von den vorstehenden Ausführungen bevorzugt derart ausgebildet, dass sie einen Anschluss für eine Speisepumpe aufweist, und dass sie eine, insbesondere druckabgesicherte, Schalteinrichtung zum Ablass von Hydraulikfluid aus dem geschlossenen Kreislauf in eine bis zu einem Leitungsanschluss führende Ablassleitung aufweist, beispielsweise aufgrund von Wärmeeffekten und/oder zur teilweisen Kühlung des im geschlossenen Hydraulikkreislauf zirkulierenden Hydraulikfluids. Damit kann dem geschlossenen Hydraulikkreislauf in kontrollierter Weise ein Teil an Hydraulikfluid von außerhalb des geschlossenen Hydraulikkreislaufes entzogen und zugeführt werden. Dies kann insbesondere zum Ausgleich von Leckageölverlusten und/oder zu Kühlungszwecken des im geschlossenen Hydraulikkreislauf umlaufenden Hydraulikfluidvolumens dienen. Eine derartige druckabgesicherte Schalteinrichtung ist beispielsweise ein Druckbegrenzungsventil.The valve device, in particular the basic valve block, is preferably designed, independently of the above statements, in such a way that it has a connection for a feed pump and that it has a switching device, in particular pressure-protected, for draining hydraulic fluid from the closed circuit into a discharge line leading to a line connection, for example due to thermal effects and / or for partial cooling of the hydraulic fluid circulating in the closed hydraulic circuit. In this way, a part of hydraulic fluid can be withdrawn from outside the closed hydraulic circuit and supplied to the closed hydraulic circuit in a controlled manner. This can serve in particular to compensate for leakage oil losses and / or for cooling purposes of the hydraulic fluid volume circulating in the closed hydraulic circuit. Such a pressure-protected switching device is, for example, a pressure limiting valve.
Grundsätzlich kann die Ventileinrichtung als mit der Konstantpumpe baulich zusammenhängende Baueinheit oder als zur Konstantpumpe separate, aber mit dieser in Fluidverbindung stehende Baueinheit ausgebildet sein. Die Erfindung richtet sich auch auf diese beiden Varianten.In principle, the valve device can be designed as a structural unit that is structurally connected with the fixed displacement pump or as a structural unit that is separate from the fixed displacement pump but is in fluid connection with it. The invention is also directed to these two variants.
Ein weiterer Aspekt der Erfindung betrifft einen geschlossenen Hydraulikkreislauf, umfassend eine erfindungsgemäße Konstantpumpe, insbesondere mit einer Ventileinrichtung, wie vorstehend beschrieben. Der geschlossenen Hydraulikkreislauf weist demnach neben einer erfindungsgemäßen Konstantpumpe einen von der Konstantpumpe mit Hydraulikfluid versorgten hydraulischen Verbraucher, insbesondere einen Hydraulikmotor, mit einem Fluidmotoreingang und einem Fluidmotorausgang, eine Hydraulikfluid hinleitende Versorgungsleitung, die den Fluidpumpenausgang mit dem Fluidmotoreingang verbindet, und eine Hydraulikfluid rückleitende Versorgungsleitung, die den Fluidmotorausgang mit dem Fluidpumpeneingang verbindet, auf.Another aspect of the invention relates to a closed hydraulic circuit, comprising a constant displacement pump according to the invention, in particular with a valve device, as described above. The closed hydraulic circuit accordingly has, in addition to a fixed displacement pump according to the invention, a hydraulic consumer supplied with hydraulic fluid from the fixed displacement pump, in particular a hydraulic motor, with a fluid motor input and a fluid motor output, a supply line leading to hydraulic fluid which connects the fluid pump output to the fluid motor input, and a hydraulic fluid returning supply line which connects the fluid motor output to the fluid pump input.
Die Erfindung betrifft auch eine Baumaschine, insbesondere einen Straßenfertiger, einen Beschicker, eine Straßenfräse, einen Stabilisierer, einen Recycler, einen Müll- oder Erdverdichter, eine Erd- oder Straßenwalze, mit wenigstens einem erfindungsgemäßen geschlossenen Hydraulickreislauf.The invention also relates to a construction machine, in particular a road finisher, a feeder, a road milling machine, a stabilizer, a recycler, a garbage or earth compactor, an earth or road roller, with at least one closed hydraulic circuit according to the invention.
Ein weiterer Aspekt der Erfindung betrifft schließlich ein Verfahren zum Betrieb einer in einem geschlossenen Hydraulikkreislauf betriebenen Konstantpumpe, insbesondere einer erfindungsgemäßen Konstantpumpe. Das erfindungsgemäße Verfahren umfasst zunächst ein Fördern von Hydraulikfluid mithilfe der Konstantpumpe hin zu einer Hochdruckseite des geschlossenen Hydraulickreislaufes. Durch dieses Fördern wird im geschlossenen Hydraulikkreislauf ein gegenüber der Niederdruckseite erhöhtes Druckniveau ("Hochdruckseite") im geschlossenen Hydraulikkreislauf zwischen dem Fluidausgang an der Konstantpumpe und dem wenigstens einen hydraulischen Verbraucher erzeugt und im Betrieb aufrecht erhalten. Dadurch erfolgt in einem weiteren Schritt ein Antreiben eines hydraulischen Verbrauchers, insbesondere Hydro- bzw. Hydraulikmotors, mithilfe des auf der Hochdruckseite geführten Hydraulikfluids. Es erfolgt ferner ein Rückführen des Hydraulikfluids vom hydraulischen Verbraucher, insbesondere Hydromotor, zur Konstantpumpe auf der Niederdruckseite des geschlossenen Hydraulikkreislaufes. Dies entspricht insoweit bis auf die Verwendung einer Konstantpumpe dem üblichen Ablauf in einem geschlossenen Hydraulikkreislauf. Ergänzend zu den vorhergehend genannten Schritten erfolgt gleichzeitig nun erfindungsgemäß ein Sammeln von Leckageöl innerhalb der Konstantpumpe in einem zur Niederdruckseite und zur Hochdruckseite des geschlossenen Hydraulikkreislaufes separaten Sammelraum. Zum möglichen Aufbau dieses Sammelraums wird auf die vorhergehenden Ausführungen Bezug genommen. Wesentlich ist, dass für das Sammeln ein gegenüber gleichzeitig der Hochdruckseite als auch der Niederdruckseite abgedichteter Sammelraum genutzt wird und das über den Sammelraum gesammeltes Leckageöl insbesondere nicht einer Saugseite der Konstantpumpe zugeführt wird. Da das erfindungsgemäße Verfahren den Betrieb der Konstantpumpe in einem geschlossenen Hydraulikkreislauf vorsieht, ist auch keine Saugseite an der Konstantpumpe vorhanden. Es ist erfindungsgemäß daher weiter vorgesehen, dass ein, insbesondere zum innerhalb des geschlossenen Hydraulikkreislaufes zirkulierenden Hydraulikfluids separates, Ableiten des Leckageöls aus der Konstantpumpe erfolgt, wodurch im Ergebnis ein Volumenanteil an Hydraulikfluid aus dem geschlossenen Hydraulikkreislauf entfernt wird. Das Ableiten erfolgt besonders bevorzugt drucklos bzw. ohne Druckdifferenz gegenüber der Außenumgebung der Konstantpumpe. Das Ableiten des Leckageöls aus der Konstantpumpe erfolgt zudem bevorzugt über einen, insbesondere ausschließlich einen einzigen, Leckageölauslass der Konstantpumpe. Das erfindungsgemäße Verfahren umfasst ferner schließlich ein Einspeisen von Hydraulikfluid in den geschlossenen Hydraulikkreislauf zum Ausgleich des in den vorhergehenden Schritten aus dem geschlossenen Hydraulikkreislauf abgezweigten Leckageöls, um das Gesamtvolumen an Hydraulikfluid in dem geschlossenen Hydraulikkreislauf zumindest im Wesentlichen möglichst konstant zu halten. Hierzu kann eine geeignete Speiseeinrichtung mit insbesondere einer zur Konstantpumpe gemäß der Erfindung separaten Speisepumpe, bei der es sich ebenfalls um eine Konstantpumpe handeln kann, vorgesehen sein.Another aspect of the invention finally relates to a method for operating a fixed displacement pump operated in a closed hydraulic circuit, in particular a fixed displacement pump according to the invention. The method according to the invention initially comprises a conveyance of hydraulic fluid with the aid of the fixed displacement pump to a high pressure side of the closed hydraulic circuit. As a result of this conveying, a pressure level ("high pressure side") that is higher than that on the low-pressure side is generated in the closed hydraulic circuit between the fluid outlet on the fixed displacement pump and the at least one hydraulic consumer and maintained during operation. As a result, in a further step, a hydraulic consumer, in particular a hydraulic or hydraulic motor, is driven with the aid of the hydraulic fluid carried on the high-pressure side. There is also a return of the hydraulic fluid from the hydraulic consumer, in particular the hydraulic motor, to the fixed displacement pump on the low-pressure side of the closed hydraulic circuit. Except for the use of a fixed displacement pump, this corresponds to the usual sequence in a closed hydraulic circuit. In addition to the steps mentioned above, according to the invention, leakage oil is now simultaneously collected within the fixed displacement pump in a collecting space separate from the low-pressure side and the high-pressure side of the closed hydraulic circuit. About the possible structure of this collecting space reference is made to the preceding statements. It is essential that a collecting space that is sealed off from both the high-pressure side and the low-pressure side is used for the collection and that the leakage oil collected via the collecting space is in particular not fed to a suction side of the fixed displacement pump. Since the method according to the invention provides for the operation of the fixed displacement pump in a closed hydraulic circuit, there is also no suction side on the fixed displacement pump. According to the invention, it is therefore further provided that the leakage oil is diverted from the fixed displacement pump, in particular separately from the hydraulic fluid circulating within the closed hydraulic circuit, whereby a volume fraction of hydraulic fluid is removed from the closed hydraulic circuit as a result. The discharge takes place particularly preferably without pressure or without a pressure difference in relation to the external environment of the fixed displacement pump. The leakage oil is also diverted from the fixed displacement pump preferably via one, in particular exclusively one, leakage oil outlet of the fixed displacement pump. The method according to the invention also finally includes feeding hydraulic fluid into the closed hydraulic circuit to compensate for the leakage oil diverted from the closed hydraulic circuit in the preceding steps in order to keep the total volume of hydraulic fluid in the closed hydraulic circuit at least substantially as constant as possible. For this purpose, a suitable feed device with, in particular, a feed pump which is separate from the constant pump according to the invention and which can also be a constant pump, can be provided.
Für die Durchführung des erfindungsgemäßen Verfahrens ist es bevorzugt, wenn das Sammeln von Leckageöl wenigstens teilweise über eine in einer Lagerachse angeordnete Durchgangsöffnung erfolgt. Damit erfolgt das Sammeln somit zumindest teilweise über einen sich mit dem Förderelement um die Rotationsachse drehenden Teilbereich des Sammelraums. Ideal ist es dabei, wenn das Sammeln des Leckageöls über einen Sammelraum erfolgt, der sich wenigstens teilweise mit dem Förderelement um die Rotationsachse mitdreht und sich insbesondere durch dieses hindurch erstreckt, ganz besonders entlang der Rotationsachse, und der wenigstens einen Teilbereich aufweist, der ortsfest gegenüber einem Pumpengehäuse der Konstantpumpe ist, insbesondere im Bereich des Leckageölauslasses.For carrying out the method according to the invention, it is preferred if the collection of leakage oil takes place at least partially via a through opening arranged in a bearing axis. The collection thus takes place at least partially via a partial area of the collecting space that rotates with the conveying element about the axis of rotation. It is ideal if the leakage oil is collected via a collecting space which at least partially rotates with the conveying element about the axis of rotation and in particular extends through it, especially along the axis of rotation, and which has at least a partial area that is stationary opposite a pump housing of the fixed displacement pump, in particular in the area of the leakage oil outlet.
Um über das Achslager austretendes Leckageöl besonders effektiv sammeln zu können, erfolgt zum Sammeln von Leckageöl im Sammelraum ein Abdichten des Sammelraums bevorzugt sowohl gegenüber der Hochdruckseite als auch der Niederdruckseite der Konstantpumpe mithilfe einer Abdichteinrichtung, ganz besonders mithilfe einer Abdichteinrichtung, wie zur erfindungsgemäßen Konstantpumpe näher beschrieben.In order to be able to collect leakage oil escaping via the axle bearing particularly effectively, to collect leakage oil in the collecting space, the collecting space is preferably sealed against both the high pressure side and the low pressure side of the fixed displacement pump with the aid of a sealing device, especially with the aid of a sealing device, as described in more detail for the fixed displacement pump according to the invention .
Es kann vorteilhaft sein, wenn die Konstantpumpe als Tandempumpe mit einer ersten Konstantpumpeneinheit und einer zweiten Konstantpumpeneinheit ausgebildet ist. Bei dieser besonderen Anordnung kann es vorgesehen sein, dass Leckageölmengen für jede Konstantpumpeneinheit separat zueinander gesammelt werden. Bevorzugt ist es jedoch, ein Vereinen der Leckageölströme der ersten und der zweiten Konstantpumpeneinheit und anschließend ein gemeinsames Ableiten der vereinten Leckageölströme aus der Tandempumpe vorzusehen, um nicht zwei separate Leckageölströme ableiten zu müssen. Ergänzend oder alternativ erfolgt auch das Speisen mit Hydraulikfluid der von den beiden Konstantpumpeneinheiten betriebenen beiden geschlossenen Hydraulikkreisläufe über eine gemeinsame Speisepumpe, die Versorgungsleitungen zu beiden geschlossenen Hydraulickreisläufen aufweist.It can be advantageous if the constant pump is designed as a tandem pump with a first constant pump unit and a second constant pump unit. With this special arrangement, it can be provided that leakage oil quantities are collected separately for each fixed displacement pump unit. However, it is preferred to combine the leakage oil flows of the first and the second constant pump unit and then jointly discharge the combined leakage oil flows from the tandem pump, so as not to provide two separate leakage oil flows having to deduce. In addition or as an alternative, the two closed hydraulic circuits operated by the two fixed displacement pump units are also supplied with hydraulic fluid via a common feed pump which has supply lines to both closed hydraulic circuits.
Nachstehend wird die Erfindung anhand der in den Figuren dargestellten Figuren näher erläutert. Es zeigen schematisch:
- Fig. 1:
- Eine Seitenansicht auf eine exemplarische Baumaschine, vorliegend ein Straßenfertiger;
- Fig. 2:
- eine Prinzipskizze zu einem geschlossenen Hydraulikkreislauf;
- Fig. 3:
- eine Prinzipskizze zur Funktionsweise einer Konstantpumpe vom Typ Außenzahnradpumpe;
- Fig. 4:
- eine perspektivische Schrägansicht auf eine zwei Konstantpumpeneinheiten aufweisende Konstantpumpe;
- Fig. 5a:
- eine Querschnittansicht durch die Konstantpumpeneinheiten aus
Fig. 4 in der Ebene I inFig. 4 (Betrachtungsrichtung gemäß Blickpfeil I) bei einer modifizierten Konstantpumpe; - Fig. 5b:
- die Querschnittansicht aus
Fig. 5a mit hervorgehobenem Sammelraum; - Fig. 6:
- eine Querschnittansicht durch eine Konstantpumpe in einer Perspektive vergleichbar zur Ebene II in
Fig. 4 (Betrachtungsrichtung gemäß Blickpfeil II) auf eine Abdichteinrichtung aus dem Stand der Technik; - Fig. 7:
- eine Querschnittansicht durch die Konstantpumpe aus
Fig. 4 in der Ebene II inFig. 4 (Betrachtungsrichtung gemäß Blickpfeil II) auf eine Abdichteinrichtung gemäß der Erfindung; - Fig. 8:
- ein Hydraulikschaltplant eines geschlossenen Hydraulikkreislaufes;
- Fig. 9a:
- ein Hydraulikschaltplan eines Moduls einer Ventileinrichtung mit Ein/Aus- und Richtungsumkehrfunktion;
- Fig. 9b:
- ein Hydraulikschaltplan eines Moduls einer Ventileinrichtung mit Ein/Aus-Funktion;
- Fig. 9c:
- ein Hydraulikschaltplan eines Moduls einer Ventileinrichtung mit stufenloser Ein/Aus- und Richtungsumkehrfunktion;
- Fig. 9d:
- ein Hydraulikschaltplan eines Moduls einer Ventileinrichtung mit stufenloser Ein/Aus-Funktion;
- Fig. 10:
- eine weitere Variation des Hydraulikschaltplans aus
Fig. 9a ; - Fig. 11:
- ein Ablaufdiagramm eines erfindungsgemäßen Verfahrens.
- Fig. 1:
- A side view of an exemplary construction machine, in the present case a road finisher;
- Fig. 2:
- a schematic diagram of a closed hydraulic circuit;
- Fig. 3:
- a schematic diagram of the functioning of a fixed displacement pump of the external gear pump type;
- Fig. 4:
- a perspective oblique view of a fixed displacement pump having two constant pump units;
- Fig. 5a:
- a cross-sectional view through the fixed displacement pump units
Fig. 4 in level I inFig. 4 (Viewing direction according to arrow I) with a modified fixed displacement pump; - Fig. 5b:
- the cross-sectional view
Figure 5a with highlighted collecting space; - Fig. 6:
- a cross-sectional view through a fixed displacement pump in a perspective comparable to plane II in
Fig. 4 (Viewing direction according to viewing arrow II) to a sealing device from the prior art; - Fig. 7:
- a cross-sectional view through the fixed displacement pump
Fig. 4 in level II inFig. 4 (Viewing direction according to viewing arrow II) on a sealing device according to the invention; - Fig. 8:
- a hydraulic circuit diagram of a closed hydraulic circuit;
- Fig. 9a:
- a hydraulic circuit diagram of a module of a valve device with on / off and direction reversal function;
- Fig. 9b:
- a hydraulic circuit diagram of a module of a valve device with an on / off function;
- Fig. 9c:
- a hydraulic circuit diagram of a module of a valve device with stepless on / off and direction reversal function;
- Fig. 9d:
- a hydraulic circuit diagram of a module of a valve device with a stepless on / off function;
- Fig. 10:
- another variation of the hydraulic circuit diagram
Figure 9a ; - Fig. 11:
- a flow chart of a method according to the invention.
Gleiche Bauteile sind in den Figuren mit gleichen Bezugszeichen gekennzeichnet, wobei nicht jedes sich in den Figuren wiederholende Bauteil separat in jeder Figur bezeichnet ist.The same components are identified by the same reference symbols in the figures, and not every component that is repeated in the figures is labeled separately in each figure.
Im vorliegenden Ausführungsbeispiel kann der geschlossene Hydraulikkreislauf 8 ferner die Ventileinrichtung 19 umfassen. Diese kann einen Grundventilblock 20 und zwei, beispielsweise an diesen angesetzte, Funktionsmodulblöcke 21 aufweisen. Das von der Konstantpumpe 9 über den Pumpenausgang 10 geförderte Hydraulikfluid passiert zunächst den Grundventilblock 20 und anschließend den hydraulischen Verbraucher 12. Über den Motorauslass 14 wird das geförderte Hydraulikfluid unter erneuter Passage des Grundventilblocks 20 im geschlossenen Hydraulikkreislauf 8 anschließend wieder zur Konstantpumpe 9 rückgeführt.In the present exemplary embodiment, the closed
Teil der Konstantpumpe 9 ist ein Sammelraum 22, in dem Leckageöl, welches im Betrieb der Konstantpumpe 9 auftritt, gesammelt wird. Das innerhalb der Konstantpumpe 9 gesammelte Leckageöl kann, insbesondere gegenüber der Außenumgebung der Konstantpumpe 9 drucklos, über einen Leckageölauslass 23 aus dem Inneren der Konstantpumpe 9 abgeführt werden. Hierzu kann eine an den Leckageölauslass 23 angeschlossene Abführleitung 24 vorgesehen sein, die das gesammelte Leckageöl vom Leckageölauslass 23 in einen Tank 25 ableitet.Part of the fixed
Schließlich kann eine Speiseeinrichtung 26 vorgesehen sein, die zum Ausgleich der Leckageölverluste im geschlossenen Hydraulikkreislauf 8 vorgesehen ist. Diese Speiseeinrichtung 26 kann eine zur Konstantpumpe 9 des geschlossenen Hydraulikkreislaufes 8 separate Speisepumpe 27 umfassen, beispielsweise eine konventionelle Konstantpumpe in einem offenen Hydraulikkreislauf, die über eine Speiseleitung 28 mit dem geschlossenen Hydraulikkreislauf 8 und/oder einer seiner Komponenten, wie im vorliegenden Ausführungsbeispiel beispielsweise der Ventileinrichtung 19, der Art verbunden ist, dass Hydraulikfluid zum Ausgleich der Leckageölverluste in den geschlossenen Hydraulikkreislauf 8 einspeisbar ist. Weitere Einzelheiten zu dem in
Jede Konstantpumpeneinheit umfasst im vorliegenden Ausführungsbeispiel als Förderelement 30 ein miteinander kämmendes Zahnradpaar 31A, 31B. Bei den Zahnrädern handelt es sich um Außenzahnräder. Der Antrieb der Konstantpumpe erfolgt über die um die Rotationsachse R (R1) rotierende Antriebswelle 17, die einstückig mit dem Zahnrad 31A der ersten Konstantpumpeneinheit 9A ausgebildet sein kann. Wesentlich ist, dass die Antriebswelle 17 und das erste Zahnrad 31A drehfest miteinander verbunden sind. Durch den kämmenden Eingriff des Zahnrads 31A in die Verzahnung des zweiten Zahnrads 31B wird das zweite Zahnrad 31B in Rotation um die Rotationsachse R2 versetzt. Jedes Zahnrad 31A und 31B umfasst in axialer Richtung der jeweiligen Rotationsachse R1 und R2 zu beiden Seiten jeweils eine gegenüber dem jeweiligen Zahnrad 31A/31B in axialer Richtung vorstehende Lagerachse 33, die in der
Die Lagerachsen 33 (konkret 33.1 bis 33.8) sind jeweils in Achslagern 35 (in Zuordnung zu den Lagerachsen 33.1 bis 33.8 in den Achslagern 35.1 bis 35.8) um die jeweilige Rotationsachse R1 und R2 rotierbar gelagert, wobei die Achslager 35 insbesondere als Gleitlager ausgebildet sein können. Die Axialsicherung der Zahnräder 31A bis 31D kann mithilfe von im Inneren des Pumpengehäuses 29 angeordneten Lagerbrillen 36A und 36B für die erste Konstantpumpeneinheit 9A und 36C und 36D für die zweite Konstantpumpe Einheit 9B, erfolgen. Die Lagerbrillen können die Achslager 35.1 bis 35.8 bilden. Die Zahnräder 31A bis 31D springen in radialer Richtung zur jeweiligen Rotationsachse R1 und R2 gegenüber der radialen Erstreckung der jeweiligen Achslager 35.1 bis 35.8 vor, so dass sie durch die Lagerbrillen 36 formschlüssig an einer nennenswerten Axialverschiebung entlang der jeweiligen Rotationsachse R1, R2 gehindert werden.The bearing axles 33 (specifically 33.1 to 33.8) are each mounted in axle bearings 35 (in association with the bearing axles 33.1 to 33.8 in the axle bearings 35.1 to 35.8) so that they can rotate about the respective rotational axis R1 and R2, whereby the axle bearings 35 can in particular be designed as slide bearings . The
Im Betrieb der Konstantpumpe 9 leckt Hydraulikfluid aus dem Förderraum 38 in axialer Richtung der Rotationsachse R1 und R2 zwischen den Lagerachsen 33 und den Achslagern 35. Dieses Leckageöl wird innerhalb der Konstantpumpe 9 in dem Sammelraum 22 gesammelt.
Über die Austrittsstelle 39.1 tritt Leckageöl beispielsweise über das Gleitlager aus, welches zwischen der Lagerachse 33.1 und dem Achslager 35.1 gebildet wird. Analog trifft dies auf die Austrittstellen 39.2 (zwischen 33.2 und 35. 2 [
Insgesamt steht damit ein zusammenhängender Sammelraum 22 innerhalb der Konstantpumpe 9 zur Verfügung, über den über die Achslager 35 austretende Leckageölströme vereint und getrennt zur Hochdruckseite und Niederdruckseite der Konstantpumpe 9 aus dieser abgeführt werden können. Wichtig ist dabei, dass diese Anordnung nicht zwingend die Verwendung einer Tandemanordnung, wie beispielhaft in der
Um ein effizientes Sammeln des Leckageöls, wie in den
Infolgedessen ist es erfindungsgemäß nun im Unterschied zur in
Für die Funktionalität des in
Der Funktionsmodulblock 21A gemäß
Mithilfe des Funktionsmodulblocks 21B kann somit beispielsweise eine Richtungsumkehr hin zu einem an die Anschlüsse MA und MB angeschlossenen hydraulischen Verbraucher, wie beispielsweise einen Hydromotor, erreicht werden.With the aid of the
Die zum Ausgang PB rückführenden Leitungsabschnitte sind ferner gegenüber einer Tankleitung mit dem Ausgang T über geeignete Druckbegrenzungsventile 46 Druck abgesichert.The line sections returning to the output PB are also protected against pressure from a tank line with the output T by means of suitable
Ein alternatives Ausführungsbeispiel gemäß
In
Im Ausführungsbeispiel gemäß
Claims (15)
dass die Konstantpumpe (9) einen an das Achslager (35) angrenzenden Sammelraum (22) für den aus dem Achslager (35) austretenden Leckageanteil des Hydraulikfluids aufweist, wobei eine Abdichteinrichtung (40) vorhanden ist, die den Sammelraum (22) gegenüber der Niederdruckseite und der Hochdruckseite der Konstantpumpe (9) abdichtet, und dass die Konstantpumpe (9) einen mit dem Sammelraum (22) verbundenen Leckageölauslass (23) zum Abführen des Leckageöls aus der Konstantpumpe (9) aufweist.A fixed displacement pump (9) for use in conveying a hydraulic fluid in a closed hydraulic circuit (8), comprising
that the fixed displacement pump (9) has a collecting space (22) adjoining the axle bearing (35) for the leakage portion of the hydraulic fluid exiting from the axle bearing (35), a sealing device (40) being present which closes the collecting space (22) on the low-pressure side and the high pressure side of the fixed displacement pump (9), and that the fixed displacement pump (9) has a leakage oil outlet (23) connected to the collecting chamber (22) for discharging the leakage oil from the fixed displacement pump (9).
dadurch gekennzeichnet,
dass der Sammelraum (22) wenigstens eines der folgenden Merkmale aufweist:
characterized,
that the collecting space (22) has at least one of the following features:
dadurch gekennzeichnet,
dass der Sammelraum (22) teilweise in und/oder an einem der folgenden Bauteile der Konstantpumpe (9) ausgebildet ist:
characterized,
that the collecting space (22) is partially formed in and / or on one of the following components of the fixed displacement pump (9):
dadurch gekennzeichnet,
dass die Abdichteinrichtung (40) wenigstens eines der folgenden Merkmale aufweist:
characterized,
that the sealing device (40) has at least one of the following features:
dadurch gekennzeich net,
dass die Konstantpumpe (9) eine Außenzahnradpumpe ist, umfassend
characterized gekennzeich net,
that the fixed displacement pump (9) is an external gear pump, comprising
dadurch gekennze ich net,
dass die Konstantpumpe (9) als Tandempumpe mit einer ersten und einer zweiten Konstantpumpeneinheit (9A, 9B) ausgebildet ist, wobei die Tandempumpe wenigstens eines der folgenden Merkmale aufweist
by that I do not mark,
that the constant pump (9) is designed as a tandem pump with a first and a second constant pump unit (9A, 9B), the tandem pump having at least one of the following features
dadurch gekennzeichnet,
dass sie eine Ventileinrichtung (19) umfasst, die an den Fluidpumpeneingang (11) und den Fluidpumpenausgang (10) angeschlossen und/oder dem Fluidpumpeneingang (11) und dem Fluidpumpenausgang (10) vorgeschaltet ist, wobei die Ventileinrichtung (19) wenigstens eine der folgenden Ventilfunktionen aufweist:
characterized,
that it comprises a valve device (19) connected to the fluid pump inlet (11) and the fluid pump outlet (10) and / or upstream of the fluid pump inlet (11) and the fluid pump outlet (10), the valve device (19) at least one of the following Has valve functions:
dadurch gekennzeichnet,
dass die Ventileinrichtung (19) als modulare Einheit mit
einem Grundventilblock (20), umfassend wenigstens
characterized,
that the valve device (19) as a modular unit with
a basic valve block (20) comprising at least
dadurch gekennzeichnet,
dass der Funktionsmodulblock (21) zur Durchführung wenigstens einer der folgenden Funktionalitäten ausgebildet ist:
characterized,
that the functional module block (21) is designed to carry out at least one of the following functionalities:
dadurch gekennzeichnet,
dass der Grundventilblock (20) zum gleichzeitigen Anschluss zweier Funktionsmodulblöcke (21) ausgebildet ist, insbesondere zur Durchführung wenigstens einer der folgenden Funktionalitäten an einem angeschlossenen Verbraucher, ganz besonders Hydromotor:
characterized,
that the basic valve block (20) is designed for the simultaneous connection of two functional module blocks (21), in particular for performing at least one of the following functionalities on a connected consumer, especially hydraulic motor:
dadurch gekennzeichnet,
dass die Ventileinrichtung (19), insbesondere der Grundventilblock (20), einen Anschluss für eine Speisepumpe (27) aufweist, und dass sie eine, insbesondere druckabgesicherte, Schalteinrichtung zum Ablass von Hydraulikfluid aus dem geschlossenen Kreislauf in eine bis zu einem Leitungsanschluss führende Ablassleitung aufweist.Fixed displacement pump (9) according to one of claims 8 to 10,
characterized,
that the valve device (19), in particular the basic valve block (20), has a connection for a feed pump (27), and that it has a, in particular pressure-protected, switching device for discharging hydraulic fluid from the closed circuit into a discharge line leading to a line connection .
umfassend die Schritte:
comprehensive the steps:
dadurch gekennzeichnet,
dass es wenigstens einen der folgenden Schritte umfasst:
characterized,
that it includes at least one of the following steps:
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102019007277.4A DE102019007277A1 (en) | 2019-10-18 | 2019-10-18 | Fixed displacement pump for use in pumping hydraulic fluid in a closed hydraulic circuit, closed hydraulic circuit, construction machine and method for operating a fixed displacement pump in a closed hydraulic circuit |
Publications (1)
Publication Number | Publication Date |
---|---|
EP3808981A1 true EP3808981A1 (en) | 2021-04-21 |
Family
ID=72852371
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP20000372.1A Withdrawn EP3808981A1 (en) | 2019-10-18 | 2020-10-09 | Constant pump for use in conveying a hydraulic fluid in a closed hydraulic circuit, closed hydraulic circuit, construction machine and method for operating a constant pump in a closed hydraulic circuit |
Country Status (4)
Country | Link |
---|---|
US (1) | US20210115921A1 (en) |
EP (1) | EP3808981A1 (en) |
CN (1) | CN112682305A (en) |
DE (1) | DE102019007277A1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102020116822A1 (en) * | 2020-06-25 | 2021-12-30 | Schwäbische Hüttenwerke Automotive GmbH | Axial pressure relief in plain bearings of pumps |
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DE7001479U (en) * | 1970-01-17 | 1971-06-03 | Joh Heinr Bornemann & Co Masch | SUBMERSIBLE PUMP WITH ONE OR MORE SHAFTS, GUIDED THROUGH A LEAKAGE CHAMBER ARRANGED BETWEEN THE PUMP HOUSING AND A GEARBOX. |
DE2307351A1 (en) | 1973-02-15 | 1974-08-22 | Bosch Gmbh Robert | METHOD AND EQUIPMENT FOR CONTROLLING THE FLOW OF A CONSTANT PUMP |
DE2555716A1 (en) * | 1975-12-11 | 1977-06-16 | Bosch Gmbh Robert | HYDROSTATIC TRANSMISSION |
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JPH08121351A (en) * | 1994-10-31 | 1996-05-14 | Shimadzu Corp | Gear pump or motor |
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CN109555682A (en) * | 2018-11-21 | 2019-04-02 | 中国航发西安动力控制科技有限公司 | A kind of self-lubricating multichannel fuel feeding gear pump |
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DE4125128C2 (en) * | 1990-08-10 | 1994-11-24 | Barmag Barmer Maschf | Gear pump |
US6973782B2 (en) * | 2003-12-19 | 2005-12-13 | Dana Corporation | Pressurized hydraulic fluid system with remote charge pump |
DE202004000183U1 (en) * | 2004-01-09 | 2004-04-01 | Sommer, Manfred | Pump for viscous fluids has a drive shaft bearing inside a hollow support and positioned inside a hollow hub mounting for the pump rotor |
US20130098011A1 (en) * | 2011-10-21 | 2013-04-25 | Michael L. Knussman | Hydraulic system having multiple closed-loop circuits |
DE102016002443A1 (en) * | 2016-02-29 | 2017-08-31 | Bomag Gmbh | Steering device, construction machine with a steering device and method for steering a steerable machine |
DE202016008445U1 (en) * | 2016-09-22 | 2018-01-05 | Seepex Gmbh | Cavity Pump |
-
2019
- 2019-10-18 DE DE102019007277.4A patent/DE102019007277A1/en not_active Withdrawn
-
2020
- 2020-10-09 EP EP20000372.1A patent/EP3808981A1/en not_active Withdrawn
- 2020-10-12 US US17/068,294 patent/US20210115921A1/en not_active Abandoned
- 2020-10-16 CN CN202011107596.7A patent/CN112682305A/en active Pending
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE7001479U (en) * | 1970-01-17 | 1971-06-03 | Joh Heinr Bornemann & Co Masch | SUBMERSIBLE PUMP WITH ONE OR MORE SHAFTS, GUIDED THROUGH A LEAKAGE CHAMBER ARRANGED BETWEEN THE PUMP HOUSING AND A GEARBOX. |
DE2307351A1 (en) | 1973-02-15 | 1974-08-22 | Bosch Gmbh Robert | METHOD AND EQUIPMENT FOR CONTROLLING THE FLOW OF A CONSTANT PUMP |
DE2555716A1 (en) * | 1975-12-11 | 1977-06-16 | Bosch Gmbh Robert | HYDROSTATIC TRANSMISSION |
DE3879423T2 (en) * | 1987-12-18 | 1993-06-24 | Hitachi Ltd | SCREW PISTON VACUUM PUMP. |
JPH08121351A (en) * | 1994-10-31 | 1996-05-14 | Shimadzu Corp | Gear pump or motor |
EP2180187A2 (en) * | 2008-10-27 | 2010-04-28 | Robert Bosch GmbH | Cog wheel machine |
DE102016100959A1 (en) * | 2016-01-20 | 2017-07-20 | FRISTAM Pumpen Schaumburg GmbH | Rotating pump and locking plate |
CN109555682A (en) * | 2018-11-21 | 2019-04-02 | 中国航发西安动力控制科技有限公司 | A kind of self-lubricating multichannel fuel feeding gear pump |
Also Published As
Publication number | Publication date |
---|---|
US20210115921A1 (en) | 2021-04-22 |
DE102019007277A1 (en) | 2021-04-22 |
CN112682305A (en) | 2021-04-20 |
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