Abstract:
A pressure-limiting valve with feed function, comprising a valve housing (20) having at least two connection points, in particular in the form of a working connection (A) and a tank connection (T), and having a spring-loaded pressure-limiting valve piston (22) which is mounted such as to be longitudinally movable in the valve housing (20), and having a spring-loaded non-return valve piston (56) for the implementation of the feed function, is characterized in that the non-return valve piston (56) is designed as a hollow piston and is mounted such as to be longitudinally movable in the valve housing (20).
Abstract:
In order to avoid cavitation in a boom cylinder (108) head end (152) at the beginning of a dig cycle, fluid from an alternate source (148, 188) is supplied to the head end (152) before or in addition to fluid supplied by the main boom-up hydraulic circuit (134, 156). In one embodiment, an electronic hydraulic valve (184, 202), related sensors (274), and control system (190) determines the beginning of a dig operation and uses fluid at an intermediate pressure to rapidly provide fluid to a boom (108) head end (152) cylinder to prevent voiding or cavitation before fluid under high pressure from the main pump (132) can be brought to the cylinder (108). An on/off fluid switch (184, 202) is activated early in a dig operation to address low pressure at the boom cylinder head end (152) and provide an alternate path for fluid into the cylinder (108) in reaction to the boom (106) being lifted by a motion of the stick (110) and bucket (114) in contact with the work surface (104).
Abstract:
Die Erfindung betrifft eine hydraulische Ventilanordnung, die insbesondere für eine mobile Arbeitsmaschine verwendet wird und die ein Ventilgehäuse (10) mit einem Zulauf kanal (34) , mit einem Ablauf kanal (42) und mit einem Verbraucherkanal (39) sowie eine Ventilbohrung (11) aufweist, die die Kanäle anschneidet. In der Ventilbohrung (11) ist von einer Neutralstellung aus in zumindest die eine Richtung in eine Arbeitsstellung ein Ventilschieber (12) axial bewegbar, mit dem die fluidischen Verbindungen zwischen den Kanälen steuerbar sind. Außerdem ist ein Druckbegrenzungs- und Einspeiseventil (45, 47) vorhanden, mit dem durch gedrosseltes Ablassen von Druckfluid in den Ablaufkanal (42) der Druck in dem Verbraucherkanal (39) begrenzbar und Druckfluid vom Ablauf kanal (42) in den Verbraucherkanal (39) einspeisbar ist. Der Erfindung liegt die Aufgabe zugrunde, eine derartige hydraulische Ventilanordnung so zu gestalten, dass niedrige Herstellkosten und eine kleine Baugröße möglich sind. Das angestrebte Ziel wird erfindungsgemäß dadurch erreicht, dass das Druckbegrenzungs- und Einspeiseventil (45, 47) in einem Hohlraum des Ventilschiebers (12) untergebracht ist.
Abstract:
A valve manifold (54) controls hydraulic flow in a hydraulic system for an air compressor unit. The manifold (54) includes a pressure relief valve (1), a cold oil bypass valve (2), a proportional flow valve (3), and an anti-cavitation valve (4). The pressure relief valve (1) diverts flow away from a fan motor (30) when the pressure of hydraulic fluid within the hydraulic system is above a predetermined level. The cold oil bypass valve (2) diverts flow away from a hydraulic cooler (42) when the temperature of hydraulic fluid within the hydraulic system is below a predetermined level. The proportional flow valve (3) diverts flow away from the fan motor (30) when the temperature of hydraulic fluid within the hydraulic system is below a predetermined level. The anti-cavitation valve (4) prevents pressure build up within the hydraulic system when the air compressor unit is shut off.
Abstract:
Die Erfindung betrifft ein Druckluft-System (1) eines Nutzfahrzeugs und ein Verfahren zu dessen Steuerung. Hierbei werden elektropneumatischen Ventile (16, 18) mit mindestens einem ersten elektrischen Steuersignal (S1) und einem zweiten elektrischen Steuersignal (S2) angesteuert und die Druckluftaufbereitungsanlage (2) durch die elektrischen Steuersignale (S1, S2) in folgende Betriebsmodi eingestellt: einen Förder-Modus (I) zur Aufnahme von Druckluft (13) des Kompressors (3) über den Drucklufteingang (8a) durch den Lufttrockner (12) zu dem Druckluftausgang (8b), einen Ruhe-Modus (II) zur Ausgabe eines pneumatischen Steuersignals über den pneumatischen Steuerausgang (8c) zum Ausschalten des Kompressors (3), einen Regenerations-Modus (3) zur Einleitung eines Regenerations-Luftstroms von dem Druckluftausgang (8b) durch den Lufttrockner (12) zu dem Entlüftungs-Ausgang (8d) und Ausgabe des pneumatischen Steuersignals über den pneumatischen Steuerausgang (8c) zum Ausschalten des Kompressors (3). Zur Vermeidung und Beseitigung von Emulsionen in der Druckluftaufbereitungsanlage (2) ist vorgesehen, dass während des Förder-Modus (I) Förderdaten (30) ermittelt werden und die Druckluftaufbereitungsanlage (2) in Abhängigkeit der Förderdaten (30) in einen Anti-Emulsions-Modus (IV) einzustellen zur Aufnahme von Druckluft (13) des Kompressors (3) an dem Drucklufteingang (8a) und Ausgabe an den Entlüftungs-Ausgang (8d), ohne Ausgabe des pneumatischen Steuersignals über den pneumatischen Steuerausgang (8c), insbesondere auch unabhängig von einer Außentemperatur.
Abstract:
An example valve includes: (i) a valve body defining a longitudinal cavity, where the valve body includes a supply inlet and an operating outlet; (ii) a cage disposed in the longitudinal cavity, where the cage includes (a) a first opening fluidly coupled to the supply outlet, and (b) a second opening fluidly coupled to the operating outlet; and (iii) a spool mounted within the cage and configured to move axially therein. When the valve is actuated, the spool moves within the cage to form a gap, thereby allowing pressurized fluid to flow from the supply inlet through the first opening, the gap, and the second opening to the operating outlet. A flow area defined around an exterior peripheral surface of the spool changes upstream from the gap at a first rate, and changes downstream from the gap at a second rate that is different from the first rate.
Abstract:
A method for generating cavitation resistance in a liquid, a portion of which can be in contact with a surface is disclosed. The disclosed method can be carried out by pressure-treating the liquid, the liquid portion in contact with the surface, and/or the surface for a sufficient time to develop resistance to cavitation. The disclosed method can be carried out when the surface is made of a material having a surface roughness that is greater than the rc of the liquid. Suitable surfaces include borosilicate glass, drawn glass, copper, lead, steel, cast iron, metal alloys and concrete. The surfaces can be ship and boat propeller surfaces, the interior of fuel lines and fuel storage containers or any other surface where cavitation can occur.
Abstract:
A device for a hydraulic rock drilling machine (1) for the protection of a piston seal unit (6) for sealing between a percussive piston (4) and a cylinder in a housing (2) of the rock drilling machine, wherein a piston guide (5) is positioned between the piston seal unit (6) and a working space in the cylinder. Between the piston guide (5) and the piston seal unit (6) there is arranged a surrounding ring- shaped inwardly open chamber (9), which is formed for receiving a hydraulic liquid volume. A hydraulic supply flow channel (12,13) for hydraulic liquid supply is connected to said chamber (9). The invention also concerns a rock drilling machine and a method.
Abstract:
A reservoir (112/212) for a hydraulic pump system includes a reservoir body (140/240), an inner wall (144/244) dividing an interior of the reservoir body into a first pressure chamber (148/248) and a second pressure chamber (152/252), and a one-way valve (156/256) connecting the first pressure chamber and the second pressure chamber. A piston assembly (180/280) forms a first cylinder portion (184a/284a) connected to the first pressure chamber and a second cylinder portion (184b/284b) that is vented. The piston is movable within the cylinder under the influence of a biasing member (192/292) to increase and decrease the overall volume of the first pressure chamber. The piston pressures a piston pump inlet (172/272) connected to the first pressure chamber and maintains a constant pressure within the first pressure chamber under a variety of piston pump operating conditions.
Abstract:
A machine (10) includes a chassis (12) and a boom assembly (14). The boom assembly (14) is movable relative to the chassis (12). The machine (10) further includes a grapple assembly (16) suspended from the boom assembly (14). The grapple assembly (16) comprises a grapple head (18) fluidly connected to a first hydraulic circuit (57) for actuating the grapple head (18) to a grasping configuration, and a hydraulic motor (24) fluidly connected to a second hydraulic circuit (71) for rotating the grapple head (18). The second hydraulic circuit (71) includes a bypass valve (72). The bypass valve (72) has a first position configured to block a fluid flow between a first port (64) of the hydraulic motor (24) and a second port (66) of the hydraulic motor (24). The bypass valve (72) also has a second position configured to allow a fluid flow between the first port (64) of the hydraulic motor (24) and the second port (66) of the hydraulic motor (24). The bypass valve (72) allows the grapple head (18) to rotate freely when the grapple head (18) is in a grasping configuration.