DE102021211345A1 - Hydraulic compact axle comprising several tubular components - Google Patents

Abstract

The invention relates to a hydraulic compact axle (10) comprising an actuator assembly (40), a pump assembly (50; 50'), a motor assembly (80) and a volume compensation assembly (90), which are each arranged concentrically with respect to a longitudinal axis (13). .According to the invention, the actuator assembly (40), the pump assembly (50; 50'), the motor assembly (80) and the volume compensation assembly (90) are each designed as a separate assembly, preferably as a separately preassembled assembly, with the said assemblies ( 40; 50; 50'; 80; 90) are arranged in a row along the longitudinal axis (13), being attached end to end to each other exclusively in pairs, the actuator assembly (40) being arranged at one end of said row.

Description

The invention relates to a hydraulic compact axle according to the preamble of claim 1.

In the context of the present patent application, a hydraulic compact axle is understood to be a self-contained assembly that includes a complete hydraulic circuit with a pump and an actuator, with a motor being provided to drive the pump.

It is known to design such a compact axle in such a way that it looks exactly like a conventional hydraulic differential cylinder with regard to the external shape. For this purpose, for example, on the US11118610B2 referred. The compact axle shown there has the disadvantage that it is difficult to assemble because many components have to be built into a long, slender outer tube. Furthermore, the compact axis can only be adapted to customer requirements with a great deal of effort. Even the adjustment of the stroke length is associated with considerable effort. A customer-specific valve assembly is hardly economically possible.

From the DE 10 2008 025 054 B4 a hydraulic system is known in which this problem has been solved in that the pump assembly, the motor assembly and the volume compensation assembly are designed as separate assemblies that can be attached to one another. However, the hydraulic system shown there is typically not designed as a compact axis because the actuator assembly is not directly attached to the rest of the assembly. If this is exceptionally the case, the actuator assembly is arranged laterally next to the other assemblies for structural reasons, so that the actuator assembly alone transmits the hydraulic forces, while the other assemblies are kept force-free. As a result, such a compact axle does not have the external shape of a conventional hydraulic differential cylinder.

An advantage of the present invention is that the corresponding compact axle has the external form of a conventional hydraulic differential cylinder, while still being easy to assemble. The compact axis can still absorb and transmit the hydraulic forces that occur during operation without excessive deformation occurring, individual components breaking or leaks occurring.

According to claim 1, it is proposed that the actuator assembly, the pump assembly, the motor assembly and the volume compensation assembly are each designed as a separate assembly, preferably as a separately preassembled assembly, with the assemblies mentioned being arranged in a row along the longitudinal axis, wherein they are only attached end to end in pairs, with the actuator assembly being located at one end of said row.

The actuator assembly can be designed as a hydraulic cylinder or as a hydraulic motor. The hydraulic cylinder can be designed as a differential or synchronous cylinder. The synchronous cylinder can be unfolded or folded once or several times. A simply folded double-rod cylinder is, for example, from DE 10 2012 012 142 A1 known. A folded, in particular a double-folded double-rod cylinder has the advantage that, on the one hand, it can be fastened to the adjacent assembly within the meaning of the invention, in particular with a threaded screw connection, while on the other hand it can be easily controlled, especially if the direction of movement of the piston rod changes frequently. Such a double-rod cylinder has an air space whose volume changes when the piston rod moves. This air space can be in permanent air exchange connection with the outside environment, for example via a sintered metal filter or via large windows in a dirt scraper. The actuator assembly may be provided with a mechanical override so that it can be moved by means other than the motor assembly, for example by hand. If the actuator assembly is designed as a hydraulic motor, it can be provided with a torque support, for which purpose the pivot pins explained below can be used, for example.

The pump assembly may include a single pump connected to the actuator in a closed hydraulic circuit. A liquid chamber of the volume compensation assembly is preferably in liquid exchange connection with the hydraulic circuit in such a way that the closed hydraulic circuit is always completely filled with pressure liquid, with no overpressure occurring there that could damage the hydraulic compact axle. The pump assembly can include two pumps that are connected in series, with the liquid chamber of the volume compensation assembly being connected between the two pumps, with the flow rates of the two pumps preferably being adjustable differently. In particular when using a differential cylinder, the different fluid flows on the two sides of the cylinder can be compensated in this way. The funding ratio in question can be fixed, as is evident from the DE 10 2010 020 690 B4 is known. It can in Be adjustable operation, for example, to compensate for pressure-dependent leaks. Said pump can be designed as an internal gear pump, as an external gear pump, as an axial piston pump, as a radial piston pump or as a vane pump.

The volume compensation assembly is preferably designed structurally similar to a hydraulic accumulator. The filling pressure of the volume-compensation assembly is between 5 and 30 bar, for example, with the high pressure of the hydraulic circuit mentioned being 200 bar, for example. Said filling pressure is therefore considerably smaller than said working pressure. Accordingly, the volume compensation assembly hardly stores any hydraulic energy, so that despite the structural similarity, there can be no question of a hydraulic accumulator. It acts more like a tank that can be positioned in any direction with respect to gravity.

The pump assembly can include at least one hydraulic valve, it being possible for at least some of the valves to be combined to form a valve assembly that can be preassembled separately. In particular, the valve assembly can include at least one check valve, at least one pressure-limiting valve, at least one load-holding valve and/or at least one overflow valve.

The motor assembly preferably includes an electric motor. The electric motor can be designed as a synchronous motor, an asynchronous motor or a direct current motor. The speed of the electric motor can be adjusted in a highly dynamic manner, preferably using an associated regulating or control device, so that the movable component of the actuator assembly can be greatly accelerated or braked. The electric motor is preferably in rotary drive connection with the at least one pump of the pump assembly explained above.

The motor assembly can include a control device with which the relevant electric motor is electrically controlled. Specifically, a motor controller and, if desired, a setpoint generator can be provided. The control device can be attached inside the compact axle or on the outside of the compact axle, with mixed forms also being conceivable. The control device can include a rotary encoder with which the rotational position and/or the rotational speed of the motor can be measured. The control device can include a pressure sensor with which the pressure of the volume compensation assembly can be measured, in particular the pressure in the relevant liquid space or in the relevant gas space. The control device can include a temperature sensor with which the temperature of the pressure fluid in the hydraulic compact axle can be measured. The motor assembly or the control device can include a replaceable battery and/or operating elements, for example buttons or rotary controls, and/or a display. The currents flowing in the motor assembly during operation can be used to measure forces, torques or other stresses that act on the compact axis. All of the measured variables mentioned can be transmitted externally via a data interface and are preferably not only used within the compact axis. Wired or wireless data interfaces can be used as the data interface. Wired data interfaces are, for example, a CAN bus or an Ethernet. Examples of wireless data interfaces are Wifi, Bluetooth, LTE or 5G-NR. Such data interfaces can be used to control the movement of the compact axis using a smartphone or a tablet computer using an operating app. If the actuator assembly is designed as a hydraulic cylinder, a linear displacement sensor can be provided, which directly measures the position of the moving part or the piston rod, and is preferably connected to the control device.

The hydraulic compact axle is preferably operated with a pressure fluid, which is preferably hydraulic oil. A gas chamber of the volume compensation assembly is preferably filled with a gas, which can preferably be pressurized that is higher than the ambient pressure. The gas is, for example, nitrogen.

It is conceivable that the various assemblies are attached to one another in pairs by means of pressing, gluing, welding or crimping.

Advantageous developments and improvements of the invention are specified in the dependent claims.

Provision can be made for the assemblies mentioned to be arranged in the sequence actuator assembly, pump assembly, motor assembly and volume compensation assembly in a row along the longitudinal axis. It is conceivable that the volume compensation assembly is arranged at another point in the series, for example between the actuator assembly and the pump assembly. The claimed arrangement has the advantage that the hydraulic fluid in the fluid chamber of the volume compensation assembly the electric motor flushed through and thus causes improved cooling.

Provision can be made for at least one part, preferably all of the assemblies mentioned, to be screwed together in pairs via a threaded connection, with the threaded connection comprising an internal and an external thread, which are formed concentrically to the longitudinal axis, and they are screwed together. As a result, a particularly stable and rigid connection can be achieved between the assemblies mentioned. As explained below, the connection can be designed in such a way that it is also leak-free when the hydraulic fluid is at high pressure from the inside. The freedom from leakage is maintained even when the compact axis is exposed to external forces, in particular the lateral forces explained below.

Provision can be made for a centering to be arranged directly adjacent to at least one threaded connection, preferably to all threaded connections, with the centering comprising two circular-cylindrical surfaces which are concentric to the longitudinal axis and abut one another. With the centering, a more precise relative alignment of the two assemblies involved can be achieved than would be the case with the threaded screw connection alone. The proposed centering requires little space in the radial direction. As a result, the wall thickness of the relevant tubular components can be made small.

It can be provided that a diameter of the circular-cylindrical surfaces is preferably smaller than an inside diameter of the associated internal thread, the centering being arranged at the longitudinal end of the component of the threaded screw connection with the external thread. With regard to a possible leakage flow path of the pressure fluid from the interior of the compact axis via the threaded connection to the outside environment, the centering is arranged inside the threaded connection, where it is preferably also used for sealing. When assembling the threaded fitting, damage to the centering and the seal mentioned is reliably avoided.

Provision can be made for a static seal to be arranged in the area of the centering, which preferably comprises a sealing ring which is arranged concentrically to the longitudinal axis. The sealing groove, which accommodates the sealing ring, is preferably arranged on the component with the external thread of the threaded screw connection. The circular-cylindrical surface on the other component preferably forms a sealing surface directly.

Provision can be made for at least one of the named assemblies, preferably all of the named assemblies, to be provided with tool engagement means, in particular with at least one spanner flat, with the tool engagement means being designed in such a way that the threaded screw connection in question can be tightened and/or released. The ideally circular-cylindrical outer shape of the compact axis offers only little contact surface for a screwing tool. This deficiency can be remedied with the proposed tool attack means.

Provision can be made for the component of the threaded connection with the external thread to have a longitudinal end face which is aligned perpendicularly to the longitudinal axis and which is braced via the relevant threaded connection with an adapted mating surface on the other component of the threaded connection. In this way, the length of the centering in the direction of the longitudinal axis can be made short, with the two components of the screwed connection nevertheless being securely aligned with regard to relative tilting. The longitudinal face is preferably flat. At least one spacer ring can be arranged between the longitudinal end face and the mating face in order to achieve a predetermined, defined relative rotational position of the two components.

Provision can be made for the pump assembly to comprise a first tubular component which is concentric with respect to the longitudinal axis and which is part of at least one associated screw connection, with at least one displacement chamber of a pump in question having a variable volume being completely surrounded by a first subassembly which can be preassembled separately, the first subassembly is accommodated in the first tubular component so as to be rotatable with respect to the longitudinal axis, the first subassembly being secured with respect to rotation about the longitudinal axis to a further component which is fixedly connected to the first tubular component. The first subassembly is preferably used identically in many variants of the hydraulic compact axis. It is one of the most expensive components of the hydraulic compact axis because high hydraulic efficiency requires high manufacturing precision. The further component is preferably a valve block of the valve assembly explained above, with a plurality of valves being accommodated in the one-piece valve block, which are connected to liquid channels delimited by the valve block. The valve block is typically designed differently for each variant of the hydraulic compact axle. With the proposed construction, the cost-saving principle "little variance with the expensive first subassembly and a lot of variance with the inexpensive valve assembly" can be implemented in the best possible way.

Provision can be made for the volume-compensation assembly to completely enclose a gas chamber, closing off a directly adjacent tubular component in a liquid-tight manner at the front, with the volume-compensation assembly preferably comprising a force introduction means. The threaded screw connection suggested above enables reliable power transmission and securely seals the liquid chamber of the volume compensation assembly. The force introduction means can be designed as a ball joint or as a pair of pivot pins, the preferably circular-cylindrical pivot pins being arranged concentrically to a common pivot axis.

Provision can be made for the hydraulic compact axle to comprise a first and a second force introduction means, with the first force introduction means being arranged on a movable component of the actuator assembly, with the second force introduction means being arranged at a distance from the first force introduction means in the direction of the longitudinal axis, with at least the second force introduction means a pair of pivot pins disposed concentrically about a common pivot axis on opposite sides of the longitudinal axis, the pivot axis being oriented perpendicular to the longitudinal axis. A ball-and-socket joint can also be considered as the force introduction means, in particular for the first force introduction means. In contrast, the pivot pins mentioned have the advantage that they can absorb an acceleration torque of the electric motor, so that the compact axis does not perform any pivoting movement about the longitudinal axis when accelerating and braking. Preferably, the pivot axis intersects the longitudinal axis. The pivot axis can also cross the longitudinal axis at a distance. It is conceivable that the second force introduction means is arranged on the end of the hydraulic compact axle opposite the first force introduction means in the direction of the longitudinal axis.

Provision can be made for the pivot axis and the longitudinal axis to intersect or intersect in the vicinity of a center of mass of the hydraulic compact axis, preferably in the area of the pump assembly, most preferably in the area of a valve assembly that is part of the pump assembly. This arrangement is advantageous when the compact axis is subjected to accelerated movement as a whole. Lateral forces can act on the compact axis, which are spatially distributed. With the proposed arrangement of the pivot pins, the resulting bending moments are minimized. The preferred arrangement of the assemblies in a row means that the center of mass is usually located near the valve assembly. The corresponding valve block is particularly suitable for attaching the trunnions to it, as this is a very solid component.

It can be provided that the motor assembly, the volume compensation assembly, the actuator assembly and/or the pump assembly are each provided with a plurality of cooling fins on their outer peripheral surface, the cooling fins preferably being spaced apart from one another by spaces, the spaces most preferably being open to the outside environment are. Ideally, such cooling ribs are not used, since a hydraulic differential cylinder has no cooling ribs. In many hydraulic applications, such as excavators, such cooling fins are easily damaged. Nevertheless, it may be necessary to provide cooling measures to prevent the compact axis from overheating. The proposed arrangement of the cooling ribs is then particularly advantageous because clogging of the intermediate spaces mentioned with dirt and the like is reliably avoided. This would greatly reduce the cooling effect.

The cooling fins can be part of a cooling device that uses heat pipes to transport heat. The heat pipes are connected, for example, to the coils of the electric motor and/or to an integrated circuit of the control device, for example via a cooling plate, in order to efficiently dissipate the heat generated there to the environment. It is conceivable that the cooling effect of the cooling ribs is improved by means of a fan, with the fan being driven electrically, for example. The cooling fins are preferably arranged in one piece on an associated tubular component.

Provision can be made for the actuator assembly to be in the form of a hydraulic cylinder, with an average outside diameter of the actuator assembly being smaller than an average outside diameter of the remaining assemblies. This design deviates from the desired ideal "outer shape of the hydraulic differential cylinder". With this outer shape, however, a significant cost saving can often be achieved by making the actuator assembly no larger than is required for the desired forces.

If the compact axis is operated at low temperatures, for example in winter is taken, it may be necessary to heat the oil. This can be done, for example, by using the above-mentioned overflow valves to pump pressure fluid in the circuit without the compact axis, in particular the movable component of the actuator assembly, moving. It is also conceivable that the electric motor is acted upon by electrical reactive power, which alone causes the motor windings to heat up, but no torque. It goes without saying that a pressure fluid is preferably used which always has the desired viscosity at the temperatures occurring during operation.

However, such pressure fluids are very expensive if they are to be usable at very low temperatures.

The hydraulic compact axle can be designed in such a way that it can supply additional hydraulic consumers and/or in such a way that it can be supplied by at least one additional pump. It goes without saying that hydraulically self-sufficient operation is preferably aimed for.

The hydraulic compact axle can be provided with a load holding device that acts to hold the moving part of the actuator assembly in place when the electric motor is not energized. This can be done, for example, by means of load-holding valves, which are preferably part of the pump assembly, in particular the valve assembly. The load can be held by means of a clamp, for example by clamping a movable piston rod of the actuator assembly to a tubular component which is part of the actuator assembly.

The hydraulic compact axle can be controlled by means of an operating element, which is designed as an operating lever or as a joystick. The operating lever can be equipped with a force feedback system, which gives the user haptic feedback about the force acting on the moving component of the actuator assembly. This force can be determined, for example, by measuring the currents flowing in the electric motor.

• - bei einem Bagger, beispielsweise an der Schaufel, am Ausleger und/oder am Stiel oder am Drehwerk
• - bei einem landwirtschaftlichen Traktor, beispielsweise am Hubwerk und/oder am Frontlader
• - bei einem Telehandler, beispielsweise am Teleskoparm zum Ein- und Ausfahren bzw. zum Anheben und Absenken
• - bei einem Gabelstapler, beispielsweise zum Anheben und zum Absenken der Hubgabel
• - bei einem Skid-Loader
• - bei einem Radlader
• - bei einem Dumper, beispielsweise zum Anheben und Absenken der Lademulde
• - bei einer Scherenhubbühne, beispielsweise zum Anheben und Absenken der Hubbühne
• - bei einer Tunnelbohrmaschine, beispielsweise zum Vortrieb
• - bei einer Windkraftanlage, beispielsweise zur Rotorblattverstellung
• - zum Öffnen bzw. Schließen von Schiebetüren, beispielsweise auf Schiffen
• - bei einer Planierraupe, beispielsweise zum Anheben und Absenken des Planierschildes und zu dessen sonstiger Ausrichtung
• - bei einer Bewegungsplattform, welche beispielsweise nach dem Prinzip eines Hexapods ausgebildet ist
• - bei einem Flugzeugschlepper
• - bei einer Lenkung eines Fahrzeugs, beispielsweise zum entsprechenden Schwenken der Räder
• - bei einem aktiven Fahrwerk, beispielsweise bei einem Neigezug oder bei einem Waggonlenk-Mechanismus
• - bei einem Retarder (Weichen)
• - bei Maschinen zur Kunststoffformgebung, beispielsweise nach dem Blasform- oder dem Spritzgussverfahren
• - bei einer Maschine zum Pressen, zum Sintern, zum Fließen, zur Keramikherstellung oder zum Pulverpressen
• - bei einer Recycling-Maschine, beispielsweise einem Shredder oder einer Müllpresse
• - bei einer Schweißmaschine
• - bei einer Maschine zum Nieten, zum Clinchen, zum Stanzen oder zum Nibbeln
• - bei einer Biegemaschine
• - bei einer Maschine zum Walzen von Bauteilen, beispielsweise zur Verstellung der Lage der Walzen
• - beim Handling bzw. beim Bewegen von Werkstücken innerhalb einer Fertigungsstraße, insbesondere zwischen den verschiedenen Fertigungsstationen
• - bei einer Maschine zur Herstellung von Lebensmitteln
• - bei einer Maschine zum Prüfen von Bauteilen
• - bei einem Stellantrieb, beispielsweise zur Pitch-Verstellung eines Flügels bzw. eines Rotorblatts, zur Verstellung einer Armatur oder zur Verstellung eines Krankenbettes
• - bei einer Klemmvorrichtung, beispielsweise zur Verstellung der Klemmbacken

The hydraulic compact axis according to the invention can replace hydraulic cylinders or rotary or swivel drives in any known machine, namely:

• - on an excavator, for example on the bucket, boom and/or stick or slewing gear
• - On an agricultural tractor, for example on the linkage and/or on the front loader
• - With a telehandler, for example on the telescopic arm for retracting and extending or for raising and lowering
• - on a forklift, for example to raise and lower the lifting fork
• - with a skid loader
• - on a wheel loader
• - on a dumper, for example to raise and lower the loading trough
• - on a scissor lift, for example to raise and lower the lift
• - in a tunnel boring machine, for example for propulsion
• - In a wind turbine, for example for rotor blade adjustment
• - for opening or closing sliding doors, for example on ships
• - On a bulldozer, for example for raising and lowering the bulldozer blade and for its other alignment
• - In a movement platform, which is designed, for example, on the principle of a hexapod
• - at an aircraft tractor
• - When steering a vehicle, for example for the appropriate pivoting of the wheels
• - With an active chassis, for example with a tilting train or with a wagon steering mechanism
• - with a retarder (points)
• - in machines for plastic molding, for example after the blow molding or injection molding process
• - in a machine for pressing, sintering, pouring, ceramic production or powder pressing
• - in a recycling machine, such as a shredder or compactor
• - at a welding machine
• - in a machine for riveting, clinching, punching or nibbling
• - at a bending machine
• - in a machine for rolling components, for example to adjust the position of the rolls
• - when handling or moving workpieces within a production line, esp particular between the various manufacturing stations
• - in a machine for the production of food
• - in a machine for testing components
• - In an actuator, for example, to adjust the pitch of a wing or a rotor blade, to adjust a fitting or to adjust a hospital bed
• - With a clamping device, for example for adjusting the clamping jaws

It goes without saying that the features mentioned above and those still to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

• 1 eine perspektivische Ansicht einer erfindungsgemäßen hydraulischen Kompaktachse;
• 2 einen Längsschnitt einer Gewindeverschraubung;
• 3 einen Längsschnitt einer Pumpenbaugruppe gemäß einer ersten Ausführungsform und die angrenzende Aktuator- bzw. Motorbaugruppe;
• 4 einen Längsschnitt einer Pumpenbaugruppe gemäß einer zweiten Ausführungsform und die angrenzende Aktuator- bzw. Motorbaugruppe;
• 5 einen Längsschnitt der Volumen-Kompensationsbaugruppe und die angrenzende Motorbaugruppe.

The invention is explained in more detail below with reference to the accompanying drawings. It shows:

• 1 a perspective view of a hydraulic compact axle according to the invention;
• 2 a longitudinal section of a threaded fitting;
• 3 a longitudinal section of a pump assembly according to a first embodiment and the adjacent actuator or motor assembly;
• 4 a longitudinal section of a pump assembly according to a second embodiment and the adjacent actuator and motor assembly;
• 5 a longitudinal section of the volume compensation assembly and the adjacent motor assembly.

1 shows a perspective view of a hydraulic compact axle 10 according to the invention. The outer shape of the compact axle 10 is selected so that it can replace a conventional hydraulic differential cylinder, the second force introduction means 12' being provided for this in particular. Accordingly, the outer shape is approximately circular-cylindrical over the entire length.

The compact axis 10 is composed of an actuator assembly 40, a pump assembly 50, a motor assembly 80 and a volume compensation assembly 90. These are arranged in the order mentioned in a row along the longitudinal axis 13, and they are only attached to one another in pairs at the front. This division into separate assemblies, which can preferably be preassembled separately from one another, is advantageous since it considerably simplifies the assembly of the compact axis. The corresponding fastenings are designed in such a way that they can transfer the forces occurring during operation with the smallest possible space requirement. In this case, the forces that are generated hydraulically by the actuator assembly 40 occur first. The present actuator assembly 40 is designed in the manner of a folded synchronous cylinder, with the corresponding movable component 41 being movable in the direction of the longitudinal axis 13 in the manner of a piston rod. Accordingly, the hydraulic forces are directed in the direction of the longitudinal axis 13 .

Furthermore, reference should be made to the acceleration forces that occur during operation, which occur, for example, when the compact axis 10 as a whole is accelerated or braked. This can happen, for example, when the compact axle is arranged on the shovel of an excavator, where the boom of the excavator arm is greatly accelerated. In such cases, considerable mass forces directed transversely to the longitudinal axis can act on the compact axle 10 in a spatially distributed manner. The fixed connections of the assemblies 40, 50, 80, 90 are therefore designed in such a way that the resulting bending moments can be transmitted rigidly and without risk of breakage. Threaded connections 20, which are explained in more detail further below, have proven to be particularly advantageous.

In applications in which the transverse forces explained above occur to a significant extent, the second force introduction means 12 are preferably used, which are designed in the form of two circular-cylindrical pivot pins 15, which are arranged concentrically to a common pivot axis 14 on opposite sides of the longitudinal axis 13. The first force introduction means 11, which is arranged at the outermost end of the movable component 41 of the actuator assembly 40, in the present case comprises a ball joint which cannot transmit any torque. In contrast, the pivot pins 15 can support the acceleration torque of the electric motor in the motor assembly 80 . Furthermore, the point of intersection between the longitudinal axis 13 and the pivot axis 14 can be arranged very close to the center of mass 17 of the compact axis 10 . This minimizes the bending moments on the threaded connections 20 caused by the transverse forces explained above.

The second force application means 12 'preferably also includes a ball joint. It is arranged on the volume compensation assembly 90 and thus on the opposite end of the compact axis 10 in the direction of the longitudinal axis 13 with respect to the first force introduction means 11. The The second force introduction means 12' is preferably used in applications in which the focus is on maximum external similarity to a conventional hydraulic differential cylinder.

Said assemblies 40, 50, 80, 90 can each comprise at least one subassembly, which in turn can preferably be preassembled separately. Here, the pump assembly 50 comprises two subassemblies, namely the first subassembly (No. 56 in 3 and 4 ) and the valve assembly 70. The valve assembly 70 comprises a valve block 71 in which at least one hydraulic valve is accommodated. The pivot pins 15 are preferably attached to the valve block 71 or formed integrally therewith.

The desired approximately circular-cylindrical outer shape has the consequence that tightening and loosening of the screw threads 20 are hardly suitable opportunities for screwing tools available. For this reason, tool application means 16 in the form of wrench flats were arranged on the outside of the compact axis 10 at various points.

The actuator assembly 40 includes a fourth tubular component 46, at the in 1 A guide 42 for the movable component 41 is arranged on the left end, which at the same time forms a hydraulic seal. In the present case, the fourth tubular component 46 is designed largely over its entire length as a circular-cylindrical tube with respect to the longitudinal axis 13 , with deviations occurring, for example, in the area of the threaded connection 20 and in the area of the guide 42 . In the context of the present application, the term “tubular component” is intended to include any component that extends along an axis, surrounding this axis in a ring shape so that it has a cavity inside, the cavity being on both opposite sides in the direction of the axis ends is open. In particular, such pipes should be included that are equipped with cooling fins (No. 88 in 3 and 4 ) are provided. Although such cooling ribs are undesirable in many applications of the compact axle because they can be easily damaged, they are sometimes necessary to prevent the compact axle 10 from overheating.

Attention should also be drawn to the electrical connection 18 of the compact axis 10, which is preferably arranged on the motor assembly 80. A special feature of the present compact axle 10 is that, in addition to this one electrical connection 18, no further connections are required, in particular no hydraulic connections.

2 shows a longitudinal section of a threaded connection 20. All threaded connections 20 of the present compact axle are preferably designed essentially according to this basic pattern.

A threaded fitting 20 comprises a first and a second component 101; 102, each of which is formed in one piece. The first component 101 is provided with the internal thread 21, wherein it is tubular in the sense explained above. The second component 102 is provided with the external thread 22 . It can be tubular, in the case of the valve block (No. 71 in 1 ) is designed as a compact component.

The internal thread 21 and the external thread 22 are screwed together. The alignment accuracy that can be achieved in this way is often not sufficient for the two assemblies associated with the threaded connection 20 to work together reliably at this interface. Therefore, the threaded fitting 20 includes a centering 24. The centering 24 includes the first and second component 101; 102 each have a circular-cylindrical surface 23 with respect to the longitudinal axis, the two circular-cylindrical surfaces 23 being adapted to one another essentially without play. This achieves an alignment transverse to the longitudinal axis. The diameter of the circular-cylindrical surfaces 23 is somewhat smaller than the inner diameter of the internal thread 21. The circular-cylindrical surface 23 is also arranged at the very end of the second component 102 with the external thread 22. FIG.

The second component 102 with the external thread 22 has a flat longitudinal face 27 which is oriented perpendicularly to the longitudinal axis and is arranged at the outermost end of the second component 102 . This longitudinal end face 27 bears at least indirectly against an adapted mating face 28 in the interior of the first component 101 . As a result, the first and the second component 101; 102 aligned with respect to a mutual tilting in such a way that their central axis coincide exactly with the longitudinal axis.

The static seal 25 should also be pointed out. Depending on where on the compact axle the screwed connection 20 is arranged, a very considerable hydraulic pressure can be present on its inside. A pressure of 200 bar, for example, can be present inside the actuator assembly or inside the pump assembly. A pressure of 30 bar, for example, can be present inside the volume compensation assembly. The already mentioned circular-cylindrical surfaces 23 are used for sealing. The circular-cylindrical surface 23 on the second component 102 serves directly as a sealing surface. In The circular-cylindrical surface 23 on the first component 101 is provided with a groove which is circular with respect to the longitudinal axis and in which a sealing ring 26 is accommodated, the sealing ring 26 being designed as an O-ring, for example. With this arrangement, when assembling the threaded fitting 20, there is little risk that the sealing ring 26 will be damaged. This risk of damage is further minimized with the chamfer 29 in the area of the longitudinal face 27 of the second component 102 .

3 shows a longitudinal section of a pump assembly 50 according to a first embodiment and the adjacent actuator or motor assembly 40; 80. In 3 A total of three threaded connections 20 can be seen, all of which are designed according to the basic pattern explained above, namely between the fourth tubular component 46 and the valve block 71, between the valve block 71 and the first tubular component 55 and between the first tubular component 55 and the second tubular component 82.

The actual pump 51 is designed as an internal gear pump, wherein it is formed entirely by a separate first subassembly 56, which is accommodated in the first tubular component 55 so that it can rotate relative to the longitudinal axis 13, wherein it is secured against rotation by means of at least one cylindrical pin 58 on the valve block 71 . This ensures that the hydraulic channels in the valve block 71 and in the first subassembly 56 are aligned opposite one another.

The first subassembly 56 comprises a pot-like main body 60 in which the internal gear 52 of the internal gear pump is rotatably accommodated, being hydrostatically and/or hydrodynamically rotatably mounted by means of the pressure fluid. In 3 below, the external gear wheel 53 of the internal gear pump meshes with the internal gear wheel 52. The corresponding tooth contact delimits the two pressure chambers 57 from one another in a fluid-tight manner. On the opposite side with respect to the longitudinal axis 13 , a comparable seal is achieved by means of a filler piece 59 , which in the present case is designed in one piece with the main body 60 . In order to increase the maximum delivery pressure, separate filling pieces can be provided which, if desired, are made in several pieces. The present internal gear pump is designed to be 4-quadrant capable, which is why the filler piece 59 is designed to be symmetrical with respect to a plane containing the longitudinal axis 13 . In the present case, the bore 61 in the shaft of the external gear wheel 53 permanently carries the pressure in the liquid chamber of the volume compensation assembly. Reference should also be made to the cover 62 of the first subassembly 56, which among other things forms the control kidneys of the internal gear pump, while also supporting the external gear 53 together with the main body 60 so that it can rotate relative to the longitudinal axis 13.

In the present case, the valve block 71 accommodates the two 3 Visible pressure relief valves 72, which each limit the pressure in the associated first 43 and second pressure chamber 44 upwards. The pressure in the first pressure chamber 43 allows the movable part 41 to be extended in the direction of the longitudinal axis 13 . The pressure in the second pressure chamber allows the movable part 41 to retract in the direction of the longitudinal axis 13 . In the present case, the actuator assembly 40 is designed as a synchronous cylinder, so that the hydraulically active surfaces of the first and second pressure chambers 43; 44 are identical. However, tolerance-related deviations from this ideal and/or temperature fluctuations can lead to the pressure in the hydraulic circuit, which is closed in the present case, rising in an undesired manner. This increase in pressure is limited upwards by the pressure-limiting valves 72 . The first and the second pressure chamber 43; 44, can each be assigned a suction valve. An anti-cavitation valve is a non-return valve which only allows a flow of fluid from the liquid chamber of the volume compensation assembly to the relevant pressure chamber 43; 44 to allow. The anti-cavitation valves can each be part of an associated pressure-limiting valve 72 . They may also be in the form of separate valves screwed into the main body 60 of the first subassembly 56, for example.

The valve assembly 70 is equipped with valves depending on the specific application of the compact axis. The present valve block 71 has the advantage that it offers a comparatively large amount of installation space for valves. It can easily be lengthened in the direction of the longitudinal axis in order to provide more installation space for valves. Next you can refer to 1 explained pivot pin can be easily attached to the outside of the valve block 71, with a safe transfer of force is guaranteed to the adjacent assemblies.

Attention should also be drawn to the air space 45 of the actuator assembly 40, the volume of which changes when the movable component moves. Since the piston is 47 in 3 is in its stowed end position, the airspace at the point marked No. 45 has a volume of zero. The air space is preferably permanently connected to the ambient air via at least one duct, it being possible for this duct to be provided with a sintered filter in order to prevent the ingress of dirt.

The second tubular component 82 of the motor assembly 80 is firmly connected to the stator 84 of the electric motor, for example glued. The second tubular component 82 can be provided with cooling ribs 88 on its outer peripheral surface, which dissipate the waste heat generated in the coil windings of the stator 84 to the environment.

The motor shaft 81 of the electric motor is fitted with two rotary bearings 86 (see also 5 ) with respect to the longitudinal axis 13 rotatably mounted. In the present case, the pivot bearings 86 are designed as radial grooved ball bearings. The bore 89 inside the motor shaft 81 carries the pressure in the liquid space of the volume compensation assembly. The motor shaft 71 is in rotary drive connection with the external gear wheel 53 via a separate clutch 104 . The corresponding coupling engagement can easily be established when assembling the associated threaded fitting 20 . The rotor 85 of the electric motor, which in the present case comprises a plurality of permanent magnets, is firmly connected to the motor shaft 81, for example glued.

4 shows a longitudinal section of a pump assembly 50' according to a second embodiment and the adjacent actuator or motor assembly 40; 80. The actuator and motor assembly 40; 80 are identical to 3 educated. The pump assembly 50' is identical to that in FIG 3 educated. With regard to the commonality in question, refer to the explanations 3 referred. In the 3 and 4 Identical or corresponding components are marked with the same reference numbers. It should also be noted that the rotational position of the sectional planes with respect to the longitudinal axis 13 in 3 and 4 differ in such a way that the pressure-limiting valves 72 are visible in each case. As a result, the internal gear 52, the external gear 53 and the filler appear different although they are actually formed identically.

The second embodiment 50' differs from the first embodiment of the pump assembly with regard to the arrangement of the pressure-limiting valves 72. In the present case, these have the same hydraulic function as with reference to FIG 3 explained. However, they are located in the main body 60 of the first subassembly 56 . As a result, the overall length of the first subassembly 56 increases. In order to achieve the greatest possible number of identical parts for all variants with the already large variety of possible variants of the compact axis, the design according to 3 preferred.

It should be noted that immediately to the right of the pressure relief valves 72 in 4 the pressure is present in the liquid chamber of the volume compensation assembly. The electric motor is designed as a so-called oil-carrying motor whose entire interior is filled with hydraulic fluid. The hydraulic fluid is selected accordingly so that it does not interfere with the function of the electric motor. In particular, it is electrically non-conductive.

5 shows a longitudinal section of the volume compensation assembly 90 and the adjacent motor assembly 80. In 3 are first two more threaded fittings 20 to recognize that after with reference to 2 explained basic principle are designed. A threaded fitting 20 is provided between the second and third tubular members 82; 83 of the motor assembly 80 is arranged. Another threaded connection 20 is arranged between the third tubular component 83 and the base body 95 of the volume compensation assembly 90 .

In 5 the second pivot bearing 86 can be seen, with which the motor shaft 81 is rotatably mounted. A rotary encoder 87 is arranged in the area of this pivot bearing 86, with which the angle of rotation of the motor shaft 81 can be measured. The corresponding measurement is used to electronically control the currents in the stator 84 . It should be noted here that the current control mentioned is also possible without rotary encoder 87 .

As already mentioned, the entire interior of the motor assembly 80 forms part of the liquid space 91 of the volume compensation assembly 90. So that the pressure fluid can reach all areas of this interior, several bores 105 are provided, which enable a corresponding exchange of liquid.

On the fourth tubular component is the in 1 visible electrical connector (No. 18 in 1 ) arranged. This preferably has a defined alignment relative to the second force introduction means 12' in the form of a ball joint, namely with regard to the rotational position with respect to the longitudinal axis 13. This can be achieved by between the longitudinal end face (No. 27 in 2 ) and the mating surface (No. 28 in 2 ) at least one spacer is installed, the thickness of which is selected during assembly so that the desired rotational position results.

The gas space 92 of the volume compensation assembly 90 has a small volume in the present case. This is due to the fact that the actuator assembly is designed as a synchronous cylinder, so that the total volume of hydraulic fluid in the actuator assembly is essentially constant, regardless of the position of the movable component. The volume compensation assembly In the present case, 90 only has to compensate for changes in the volume of the pressure fluid, which result, for example, from a change in temperature or from internal leaks.

If the actuator assembly is in the form of a differential cylinder, the gas space is preferably made significantly larger.

In the present case, the gas space 92 is delimited in a fluid-tight manner by a membrane 93 from the liquid space 91 . The present pot-shaped membrane 93 consists, for example, of an elastomer, so that it can deform elastically in order to compensate for a change in the volume of the pressure fluid in the fluid chamber 91 . The gas space 92 is filled with a gas, which is preferably dry nitrogen. This gas can be delivered using a (in 5 (not visible) filling valve, which is accommodated in the base body 95. The membrane 93 is protected from damage by a substantially rigid perforated plate 94 . The perforated plate 94 is designed as a flat plate with a constant thickness, with a large number of bores passing through it in the direction of the longitudinal axis 13 .

Diaphragm 93 with orifice plate 94 is clamped between the longitudinal face (#27 in 2 ) and the mating surface (No. 28 in 2 ) clamped to the associated threaded fitting 20 and therefore held firmly.

The one-piece base body 95 of the volume compensation assembly 90 is pot-shaped, tightly sealing the associated longitudinal end face of the third tubular component 83 . On its end face pointing outwards in the direction of the longitudinal axis 13, a second force transmission means 12' is arranged, which in the present case is designed as a ball and socket joint. However, it can also be in the form of pivot pins in accordance with in 1 shown other second force application means (No. 12 in 1 ) be trained. It goes without saying that only one of the second force introduction means explained is used to introduce forces.

reference list

10

hydraulic compact axle

11

first means of introducing force

12

second power transmission means (first embodiment)

12'

second force introduction means (second embodiment)

13

longitudinal axis

14

pivot axis

15

trunnion

16

tool attack

17

center of mass

18

electrical connection

20

threaded fitting

21

inner thread

22

external thread

23

circular cylindrical surface

24

centering

25

static seal

26

sealing ring

27

longitudinal face

28

counter surface

29

chamfer

40

actuator assembly

41

moving component

42

guide

43

first pressure room

44

second pressure room

45

airspace

46

fourth tubular component

47

Pistons

50

Pump assembly (first embodiment)

50'

Pump assembly (second embodiment)

51

pump

52

internal gear

53

external gear

54

check valve

55

first tubular component

56

first subassembly

57

displacement space

58

Cylindrical pin (anti-twist device)

59

filler piece

60

Main body of the first subassembly

61

drilling

62

Lid

70

valve assembly

71

valve block (additional component)

72

pressure relief valve

80

engine assembly

81

motor shaft

82

second tubular component

83

third tubular component

84

stator

85

rotor

86

pivot bearing

87

encoder

88

cooling fin

89

drilling

90

volume compensation assembly

91

liquid space

92

gas space

93

membrane

94

perforated plate

95

body

96

clamping ring

101

first component

102

second component

103

gap

104

coupling

105

drilling

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• US11118610B2 [0003]
• DE 102008025054 B4 [0004]
• DE 102012012142 A1 [0007]
• DE 102010020690 B4 [0008]

Claims (14)

Hydraulic compact axle (10) comprising an actuator assembly (40), a pump assembly (50; 50'), a motor assembly (80) and a volume compensation assembly (90), which are each arranged concentrically with respect to a longitudinal axis (13), characterized in that that the actuator subassembly (40), the pump subassembly (50; 50'), the motor subassembly (80) and the volume compensation subassembly (90) are each designed as a separate subassembly, preferably as a separately preassemblable subassembly, with the named subassemblies (40 ; 50; 50';80; 90) are arranged in a row along the longitudinal axis (13) being attached end-to-end exclusively in pairs, the actuator assembly (40) being arranged at one end of said row. Hydraulic compact axle (10) according to claim 1 , wherein said assemblies (40; 50; 50';80; 90) in the order actuator assembly (40), pump assembly (50; 50'), motor assembly (80) and volume compensation assembly (90) in a row along the longitudinal axis (13) are arranged. Hydraulic compact axle (10) according to one of the preceding claims, wherein at least one part, preferably all, of the said assemblies (40; 50; 50'; 80; 90) are screwed together in pairs via a threaded screw connection (20), the threaded screw connection (20 ) each having an internal and an external thread (21; 22), which are formed concentrically to the longitudinal axis (13), wherein they are screwed together. Hydraulic compact axle (10) according to claim 3 , wherein a centering (24) is arranged immediately adjacent to the at least one threaded connection (20), preferably to all threaded connections (20), the centering (20) each comprising two circular-cylindrical surfaces (23) which are concentric to the longitudinal axis (13 ) are formed abutting each other. Hydraulic compact axle (10) according to claim 4 , wherein a diameter of the circular-cylindrical surfaces (23) is preferably smaller than an inner diameter of the associated internal thread (21), the centering (24) being arranged at the longitudinal end of the component (102) of the threaded screw connection (20) with the external thread (22). Hydraulic compact axle (10) according to one of Claims 4 or 5 , wherein in the area of the centering (24) a static seal (25) is arranged, which preferably comprises a sealing ring (26) which is arranged concentrically to the longitudinal axis (13). Hydraulic compact axle (10) according to one of claims 3 until 6 , wherein at least one of said assemblies (40; 50; 50';80; 90), preferably all said assemblies (40; 50; 50';80; 90), each with tool application means (16), in particular with at least one wrench flat, are provided, the tool application means (16) being designed in such a way that the threaded screw connection (20) in question can be tightened and/or released. Hydraulic compact axle (10) according to one of claims 3 until 7 , wherein the component (102) of the screwed connection (20) with the external thread (20) has a longitudinal end face (27) aligned perpendicularly to the longitudinal axis (13) which, via the screwed connection in question (20), has an adapted mating surface (28) on the other component (101) of the threaded fitting (20) is clamped. Hydraulic compact axle (10) according to one of claims 3 until 8th , wherein the pump assembly (50; 50') comprises a first tubular component (55) which is concentric with respect to the longitudinal axis (13) and which is part of at least one associated threaded screw connection (20), with at least one displacement chamber (57) of variable volume of a relevant pump (51) is completely surrounded by a separately preassemblable first subassembly (56), the first subassembly (56) being accommodated in the first tubular component (55) such that it can rotate with respect to the longitudinal axis (13), the first subassembly (56) with respect to torsion is secured about the longitudinal axis (13) to a further component (71) which is firmly connected to the first tubular component (55). Hydraulic compact axle (10) according to one of claims 3 until 9 , as far as this on claim 2 is retracted, wherein the volume compensation assembly (90) completely encloses a gas space (92), wherein it liquid-tightly closes an immediately adjacent tubular component (83) at the front, wherein the volume compensation assembly (90) preferably comprises a force introduction means (12'). Hydraulic compact axle (10) according to one of the preceding claims, wherein the hydraulic compact axle (10) comprises a first and a second force introduction means (11; 12; 12'), the first force introduction means (11) on a movable component (41) of the actuator assembly (40) is arranged, wherein the second force introduction means (12; 12 ') in the direction of the longitudinal axis (13) at a distance from the first force introduction means (11), wherein at least the second force introduction means comprises a pair of pivot pins (15) which are arranged concentrically to a common pivot axis (14) on opposite sides of the longitudinal axis (13), the pivot axis (14) being perpendicular to the longitudinal axis ( 13) is aligned. Hydraulic compact axle (10) according to claim 11 , wherein the pivot axis (14) and the longitudinal axis (13) intersect or intersect in the vicinity of a center of mass (17) of the hydraulic compact axis (10), preferably in the area of the pump assembly (50; 50'), most preferably in the area of a Valve assembly which is part of the pump assembly (50; 50'). Hydraulic compact axle (10) according to one of the preceding claims, wherein the motor assembly (80), the volume compensation assembly (90), the actuator assembly (40) and/or the pump assembly (50; 50') are each provided with a plurality of cooling fins ( 88), the cooling fins (88) preferably being spaced from each other by gaps, which gaps are most preferably open to the outside environment. Hydraulic compact axle (10) according to one of the preceding claims, wherein the actuator assembly (40) is designed as a hydraulic cylinder, with an average outside diameter of the actuator assembly (40) being smaller than an average outside diameter of the remaining assemblies (50; 50', 80; 90). .

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