EP0582099B1 - Hydraulic system with load sensing - Google Patents
Hydraulic system with load sensing Download PDFInfo
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- EP0582099B1 EP0582099B1 EP93110985A EP93110985A EP0582099B1 EP 0582099 B1 EP0582099 B1 EP 0582099B1 EP 93110985 A EP93110985 A EP 93110985A EP 93110985 A EP93110985 A EP 93110985A EP 0582099 B1 EP0582099 B1 EP 0582099B1
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- port
- load
- valve
- hydraulic
- sensing
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- 239000012530 fluid Substances 0.000 claims abstract description 12
- 230000002441 reversible effect Effects 0.000 claims 1
- 230000011664 signaling Effects 0.000 description 14
- 239000007788 liquid Substances 0.000 description 6
- 230000007935 neutral effect Effects 0.000 description 3
- 238000011161 development Methods 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 230000005284 excitation Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
- F15B21/08—Servomotor systems incorporating electrically operated control means
Definitions
- the invention relates to a hydraulic system with a pump, the output pressure of which is controlled as a function of a pressure present at a load signaling connection, a reservoir, a hydraulic function, a control valve, by means of which the hydraulic function can be connected to the pump or the reservoir depending on control signals, and a load signaling valve.
- Some agricultural tractors have closed hydraulic systems, in which control valves in their neutral position block the flow of liquid from the pump (closed center system). Furthermore, in these systems the hydraulic fluid delivery quantity can be compensated in such a way that only the required quantity of fluid is supplied by the pump (power-on-demand).
- some attachments that can be coupled to the tractor have hydraulic systems or components that require a hydraulic system that delivers a constant pressure. Therefore, if a control valve of the tractor hydraulic system described above is used to control the fluid flow to the hydraulic functions of an implement with constant pressure request, the hydraulic pump of the tractor must be operated continuously at maximum operating pressure. This results in higher power losses than necessary. This also increases fuel consumption and the result is an additional heat load.
- EP-A-0 010 860 describes a load signaling control for a hydraulic system with the features mentioned in the introduction, in which a load signal is tapped behind a main flow control opening of a control valve which operates a hydraulic function.
- the load signal is fed to a device by means of which the liquid delivery of the pump is changed as a function of changes in the load signal.
- the hydraulics of an attachment must be adapted and supplemented by a control valve according to EP-A-0 010 860.
- valve kits which are usually supplied for attachments with closed hydraulic systems, in order to be able to connect them to tractors with open hydraulic systems.
- an electrical control signal from the attachment is used to control a relief valve of the valve kit.
- the operator In this mode of operation, the operator must carefully adjust the tractor valve that supplies the hydraulic fluid to keep power losses to a minimum. Even with such a setting, there is an uninterrupted flow of liquid even when the implement function is not operated. This leads to undesirable performance losses.
- the object on which the invention is based is seen in providing a solution for a hydraulic system of the type mentioned at the outset by means of which the problems described can be overcome.
- the hydraulic system should enable a simpler and more effective interface between an attachment function and a closed hydraulic system with a compensated amount of liquid, in which the pump pressure is limited to the required level.
- This interface should not require extensive hydraulic installation work or valve modifications in order to obtain a load signal in the event of multiple attachment functions.
- the interface should be content with low electrical power, which is only used when the pump is required to deliver a maximum pressure.
- the hydraulic system according to the invention can be used particularly advantageously in a work vehicle, for example a cordless tractor.
- the output pressure of the hydraulic pump of the tractor hydraulic system is automatically controlled depending on a load signal.
- a control valve downstream of the pump which can be an attachment control valve or a valve for a hydraulically actuated tractor function, controls the fluid flow between the pump, a reservoir and the attachment or the tractor function.
- An electromagnetic load signaling valve controls the hydraulic connection between the pump outlet, the load signaling connection of the pump and the reservoir. It contains a valve part, which is pushed into a first position by a spring, in which it connects the load signaling connection to the storage container. In this position, the pump pressure is regulated down to the standby pressure.
- the valve part can be brought into a second position by energizing a solenoid coil, in which the pump outlet pressure is applied to the load signaling connection, as a result of which the pump outlet pressure is raised to its maximum value.
- the solenoid coil is energized by a control circuit whenever the implement control valve is actuated. Excitation is interrupted if the implement control valve is not actuated.
- the functions of the load signaling valve can be integrated, for example, in a lifting valve of the control hydraulics for the three-point linkage of an agricultural tractor.
- FIG. 1 a closed hydraulic system (closed center hydraulic system) is shown in FIG. 1, as can be used, for example, in an agricultural tractor, not shown.
- the part of the hydraulic system shown contains a pump 12 and a sump or reservoir 18.
- the pump 12 generates a liquid pressure in the pump outlet line 14, which depends on a load pressure present at the load signaling connection 16.
- the hydraulic system 10 shown contains a pilot, servo or solenoid-operated control valve 20, by means of which the connections between the pump 12, the sump 18 and a hydraulic function can be controlled.
- the hydraulic function is, for example, a hydraulic cylinder 22 of an attachment, not shown, which can be mounted on the tractor.
- the control valve 20 shown is actuated by a solenoid.
- the invention can also be carried out with a valve controlled by hydraulic fluid or air pressure.
- the control valve 20 can be installed on the tractor as well as on the attachment.
- the hydraulic system 10 can also contain further servo or manual control valves, not shown, for influencing additional hydraulic functions.
- the pump connection of the control valve 20 is connected to the pump outlet line 14 via the line 26 and connecting members 24.
- the return connection of the control valve 20 is connected to the sump 18 via the line 30 and connecting members 28.
- the hydraulic system 10 of the tractor can also contain a connecting member 32 and a line 34, which are connected to the load signaling connection 16 via a shuttle valve 36. In the present exemplary embodiment, however, the connecting member 32 is closed and unused.
- Other parts of a tractor hydraulic system 38 are connected to the hydraulic system 10 shown via the pump outlet line 14, a load reporting line 37 and a return line 39.
- a solenoid-controlled or servo-controlled inflow control valve 40 has a housing in which a first connection 42, which is connected to the pump outlet line 14, a second connection 44, which is connected to the load-reporting connection 16 via the shuttle valve 36, and a third connection 46 connected to the sump 18.
- the inflow control valve 40 includes a valve member 48 which can be moved between a first position and a second position. In the first position shown, the first connection 42 is blocked and the second connection 44 is connected to the third connection 46. In the second position, the first connection 42 is connected to the second connection 44 and the third connection 46 is blocked.
- a spring 50 is biased and urges the valve member 48 into its first position.
- a servo device 52 such as a solenoid, is excitable to move the valve member 48 to its second position.
- Each of the solenoid coils of the control valve 20 is preferably controlled by a valve driver 60, as described for example by US-A-4,964,014.
- the valve drivers 60 in turn can be controlled by an electronic control unit 62, as described for example by US-A-4,518,044.
- the two valve drivers 60 are supplied with current by a battery 64 via a current-sensing resistor R1. If one or both of the valve drivers 60 is energized, a comparison circuit 66 reacts to the voltage drop that forms across the resistor R1 and excites the coil 52 of the inflow control valve 40. As a result, the valve part 48 is always shifted into its second position when at least one coil of the Control valve 20 is excited. However, the valve member 48 remains in its first position when none of the coils of the control valve 20 is energized.
- the inflow control valve 40 connects the pump outlet line 14 to the load-reporting connection 16, so that the pump 12 of the hydraulic system 10 adjusts to the maximum outlet pressure.
- a high flow rate can be achieved at the control valve 20 and the hydraulic cylinder 22 of the attachment. All that is required is a small flow control valve 40 that can operate at a low electrical power level since it only needs to provide a low flow rate load signal to the pump 12 to generate a maximum pump output pressure.
- the hydraulic system 10 shown in FIG. 1 controls high pressures only when the hydraulic cylinder 22 of the attachment is actuated.
- the pump 12 only supplies the required amount of liquid.
- any electro-hydraulic valve of the tractor can be used to control the fluid pressure connection to the load signaling connection 16 of the pump 12. As will be described in detail later, it is also possible to use the tractor's own hoist control valve here.
- FIG. 2 shows a second exemplary embodiment in which the inflow control valve 40 has been replaced by a hoist control valve 70.
- the hoist control valve 70 contains a housing with a first connection 72, which is connected to the pump outlet line 14, a second connection 74, which is connected via a shuttle valve 36 to the load-reporting connection 16 of the pump 12, and a third connection 76, which is connected to the sump 18 is connected, a fourth connection 78, which is connected to hydraulic cylinders 80, and a fifth connection 82, which is connected to both the load reporting connection 16 and to the second connection 74.
- the hoist control valve 70 contains a valve part 71 which can be moved into the first neutral position shown, in which the first connection 72, the fourth connection 78 and the fifth connection 82 are blocked and the second connection 74 is connected to the third connection 76 .
- a second (lifting) position of the valve part 71 the first connection 72 is connected to the fifth connection 82 and the second connection 84 to the fourth connection 78 and the third connection 76 is blocked.
- a third (lowering) position of the valve part 71 the first connection 72 and the fifth connection 82 are blocked and the second connection 74 and the fourth port 78 is connected to the third port 76.
- the valve part 71 is urged into its first, neutral position by prestressed springs 84 and 86 and can be brought into its second or third position by excitable magnet coils 88 and 90.
- the hoist valve 70 is moved into its second position, in which the pump outlet pressure is connected to the load signaling connection 16, so that the pump 12 of the hydraulic system 10 has its builds up maximum hydraulic pressure.
- the pump outlet pressure is applied to the hydraulic cylinders (hoist cylinders) 80 so that they extend fully. This ensures that whenever the control valve 20 is actuated, the lifting mechanism (not shown) is fully raised, so that it does not interfere with the operation of the hydraulic cylinder 22 located on the attachment (not shown).
- FIG. 3 The embodiment shown in FIG. 3 is similar to that of FIG. 2. In the embodiment of FIG. 3, however, there is no line through which the pump outlet is connected directly to an inlet of the control valve 20. Instead, a line 92 connects the fourth port 78 of the hoist valve 70 to the inlet of an implement control valve 20. In the embodiment according to FIG. 3, the hoist valve 70 controls the fluid connection to the load signaling port 16 and the connection between the pump 12 and the control valve 20.
- the lifting cylinder 80 can also be released from the lifting valve 70, since they should remain fully extended during the operation of the control valve 20.
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- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Fluid-Pressure Circuits (AREA)
- Lifting Devices For Agricultural Implements (AREA)
- Diaphragms For Electromechanical Transducers (AREA)
- Lubrication Of Internal Combustion Engines (AREA)
- Actuator (AREA)
- Vehicle Body Suspensions (AREA)
- Lift Valve (AREA)
Abstract
Description
Die Erfindung betrifft ein Hydrauliksystem mit einer Pumpe, deren Ausgangsdruck in Abhängigkeit eines an einem Lastmeldeanschluß anstehenden Drucks gesteuert wird, einem Vorratsbehälter, einer Hydraulikfunktion, einem Steuerventil, durch das in Abhängigkeit von Steuersignalen die Hydraulikfunktion wahlweise mit der Pumpe oder dem Vorratsbehälter verbindbar ist, und einem Lastmeldeventil.The invention relates to a hydraulic system with a pump, the output pressure of which is controlled as a function of a pressure present at a load signaling connection, a reservoir, a hydraulic function, a control valve, by means of which the hydraulic function can be connected to the pump or the reservoir depending on control signals, and a load signaling valve.
Einige landwirtschaftliche Schlepper weisen geschlossene Hydrauliksysteme auf, bei denen Steuerventile in ihrer Neutralstellung den Flüssigkeitsdurchfluß von der Pumpe sperren (Closed-Center-System). Ferner kann bei diesen Systemen die Hydraulikflüssigkeitsabgabemenge derart kompensiert sein, daß lediglich die benötigte Flüssigkeitsmenge von der Pumpe geliefert wird (Power-on-Demand). Im Gegensatz hierzu weisen einige an den Schlepper ankoppelbare Anbaugeräte Hydrauliksysteme oder -komponenten auf, die ein Hydrauliksystem erfordern, welches einen konstanten Druck liefert. Wird daher ein Steuerventil des oben beschriebenen Schlepperhydrauliksystems verwendet, um den Flüssigkeitsstrom zu den Hydraulikfunktionen eines Anbaugerätes mit Konstantdruckanforderung zu steuern, so muß die Hydraulikpumpe des Schleppers ständig bei maximalem Betriebsdruck betrieben werden. Hierdurch entstehen höhere Leistungsverluste als erforderlich. Damit steigt auch der Treibstoffverbrauch, und eine zusätzliche Wärmebelastung ist die Folge.Some agricultural tractors have closed hydraulic systems, in which control valves in their neutral position block the flow of liquid from the pump (closed center system). Furthermore, in these systems the hydraulic fluid delivery quantity can be compensated in such a way that only the required quantity of fluid is supplied by the pump (power-on-demand). In contrast, some attachments that can be coupled to the tractor have hydraulic systems or components that require a hydraulic system that delivers a constant pressure. Therefore, if a control valve of the tractor hydraulic system described above is used to control the fluid flow to the hydraulic functions of an implement with constant pressure request, the hydraulic pump of the tractor must be operated continuously at maximum operating pressure. This results in higher power losses than necessary. This also increases fuel consumption and the result is an additional heat load.
Eine Lösung dieses Problems kann darin gesehen werden, den Schlepper mit einer nicht geregelten Druckquelle sowie einem Rückmeldeanschluß zu versehen und auf dem Anbaugerät eine hydraulische Lastmeldeleitung zu installieren, die den Hydraulikdruck der Anbaugerätefunktion erfaßt. Dieser Lösungsweg erfordert jedoch Veränderungen an der Anbaugerätehydraulik (Hydraulikkreis und Ventilanordnung), was sehr kompliziert und teuer werden kann, wenn mehrere Funktionen berücksichtigt werden müssen.A solution to this problem can be seen in providing the tractor with a non-regulated pressure source and a feedback connection and one on the implement Install hydraulic load signaling line that detects the hydraulic pressure of the implement function. However, this approach requires changes to the implement hydraulics (hydraulic circuit and valve arrangement), which can be very complicated and expensive if several functions have to be taken into account.
Die EP-A-0 010 860 beschreibt eine Lastmeldesteuerung für ein Hydrauliksystem mit den eingangs genannten Merkmalen, bei dem ein Lastsignal hinter einer Hauptdurchflußsteueröffnung eines Steuerventils, welches eine Hydraulikfunktion bedient, abgegriffen wird. Das Lastsignal wird einer Einrichtung zugeführt, durch die die Flüssigkeitsabgabe der Pumpe in Abhängigkeit von Änderungen des Lastsignals verändert wird. Auch hier muß die Hydraulik eines Anbaugerätes angepaßt und durch ein Steuerventil gemäß der EP-A-0 010 860 ergänzt werden.EP-A-0 010 860 describes a load signaling control for a hydraulic system with the features mentioned in the introduction, in which a load signal is tapped behind a main flow control opening of a control valve which operates a hydraulic function. The load signal is fed to a device by means of which the liquid delivery of the pump is changed as a function of changes in the load signal. Here too, the hydraulics of an attachment must be adapted and supplemented by a control valve according to EP-A-0 010 860.
Eine andere Lösung erfordert die Verwendung von Ventilbausätzen, die üblicherweise für Anbaugeräte mit geschlossenen Hydrauliksystemen geliefert werden, um diese an Schlepper mit offenen Hydrauliksystemen anschließen zu können. Bei einem derartigen Ventilbausatz wird ein elektrisches Steuersignal des Anbaugerätes verwendet, um ein Entlastungsventil des Ventilbausatzes anzusteuern. Bei dieser Betriebsweise muß die Bedienungsperson das Schlepperventil, das die Hydraulikflüssigkeit liefert, sorgfältig einstellen, um Leistungsverluste klein zu halten. Selbst mit einer solchen Einstellung herrscht ein ununterbrochener Flüssigkeitsstrom, auch wenn die Anbaugerätefunktion nicht betätigt wird. Dies führt zu unerwünschten Leistungsverlusten.Another solution requires the use of valve kits, which are usually supplied for attachments with closed hydraulic systems, in order to be able to connect them to tractors with open hydraulic systems. In such a valve kit, an electrical control signal from the attachment is used to control a relief valve of the valve kit. In this mode of operation, the operator must carefully adjust the tractor valve that supplies the hydraulic fluid to keep power losses to a minimum. Even with such a setting, there is an uninterrupted flow of liquid even when the implement function is not operated. This leads to undesirable performance losses.
Die der Erfindung zugrunde liegende Aufgabe wird darin gesehen, für ein Hydrauliksystem der eingangs genannten Art eine Lösung anzugeben, durch die sich die geschilderten Probleme überwinden lassen. Insbesondere soll das Hydrauliksystem ein einfacheres und effektiveres Interface zwischen einer Anbaugerätefunktion und einem geschlossenen Hydrauliksystem mit kompensierter Flüssigkeitsmenge ermöglichen, bei der der Pumpendruck auf das erforderliche Maß begrenzt wird. Dieses Interface soll keine extensiven Hydraulikinstallationsarbeiten oder Ventilmodifikationen erfordern, um für den Fall mehrerer Anbaugerätefunktionen ein Lastmeldesignal zu gewinnen. Ferner soll sich das Interface mit geringer elektrischer Leistung begnügen, die nur dann gebraucht wird, wenn von der Pumpe die Abgabe eines maximalen Drucks gefordert wird.The object on which the invention is based is seen in providing a solution for a hydraulic system of the type mentioned at the outset by means of which the problems described can be overcome. In particular, the hydraulic system should enable a simpler and more effective interface between an attachment function and a closed hydraulic system with a compensated amount of liquid, in which the pump pressure is limited to the required level. This interface should not require extensive hydraulic installation work or valve modifications in order to obtain a load signal in the event of multiple attachment functions. Furthermore, the interface should be content with low electrical power, which is only used when the pump is required to deliver a maximum pressure.
Die Aufgabe wird ausgehend von dem Oberbegriff des Patentanspruches 1 durch dessen kennzeichnende Merkmale gelöst. Weitere vorteilhafte Ausgestaltungen und Weiterbildungen der Erfindung gehen aus den Unteransprüchen hervor.The object is achieved on the basis of the preamble of
Das erfindungsgemäße Hydrauliksystem läßt sich besonders vorteilhaft bei einem Arbeitsfahrzeug, beispielsweise einem Akkerschlepper anwenden. Dabei wird der Ausgangsdruck der Hydraulikpumpe des Schlepperhydrauliksystems automatisch in Abhängigkeit eines Lastmeldesignals gesteuert. Ein der Pumpe nachgeordnetes Steuerventil, bei dem es sich um ein Anbaugerätesteuerventil oder ein Ventil für eine hydraulisch betätigbare Schlepperfunktion handeln kann, steuert den Flüssigkeitsfluß zwischen der Pumpe, einem Vorratsbehälter und dem Anbaugerät oder der Schlepperfunktion. Ein elektromagnetisches Lastmeldeventil steuert die hydraulische Verbindung zwischen dem Pumpenausgang, dem Lastmeldeanschluß der Pumpe und dem Vorratsbehälter. Es enthält ein Ventilteil, das durch eine Feder in eine erste Lage gedrängt wird, in der es den Lastmeldeanschluß mit dem Vorratsbehälter verbindet. In dieser Lage wird der Pumpendruck auf den Bereitschaftsdruck herunter geregelt. Das Ventilteil läßt sich durch Erregen einer Magnetspule in eine zweite Lage bringen, in der der Pumpenausgangsdruck an den Lastmeldeanschluß angelegt wird, wodurch der Pumpenausgangsdruck auf seinen maximalen Wert hochgefahren wird. Durch einen Steuerkreis wird die Magnetspule immer dann erregt, wenn das Anbaugerätesteuerventil betätigt wird. Die Erregung wird unterbrochen, wenn keine Betätigung des Anbaugerätesteuerventils erfolgt. Die Funktionen des Lastmeldeventils können beispielsweise in ein Hubventil der Regelhydraulik für die Dreipunktaufhängung eines Ackerschleppers integriert werden.The hydraulic system according to the invention can be used particularly advantageously in a work vehicle, for example a cordless tractor. The output pressure of the hydraulic pump of the tractor hydraulic system is automatically controlled depending on a load signal. A control valve downstream of the pump, which can be an attachment control valve or a valve for a hydraulically actuated tractor function, controls the fluid flow between the pump, a reservoir and the attachment or the tractor function. An electromagnetic load signaling valve controls the hydraulic connection between the pump outlet, the load signaling connection of the pump and the reservoir. It contains a valve part, which is pushed into a first position by a spring, in which it connects the load signaling connection to the storage container. In this position, the pump pressure is regulated down to the standby pressure. The valve part can be brought into a second position by energizing a solenoid coil, in which the pump outlet pressure is applied to the load signaling connection, as a result of which the pump outlet pressure is raised to its maximum value. The solenoid coil is energized by a control circuit whenever the implement control valve is actuated. Excitation is interrupted if the implement control valve is not actuated. The functions of the load signaling valve can be integrated, for example, in a lifting valve of the control hydraulics for the three-point linkage of an agricultural tractor.
Anhand der Zeichnung, die Ausführungsbeispiele der Erfindung zeigt, werden nachfolgend die Erfindung sowie weitere Vorteile und vorteilhafte Weiterbildungen und Ausgestaltungen der Erfindung näher beschrieben und erläutert.The invention and further advantages are described below with reference to the drawing, which shows exemplary embodiments of the invention and advantageous developments and refinements of the invention described and explained in more detail.
Es zeigt:
- Fig. 1
- die schematische Darstellung eines Hydraulikkreises gemäß einer ersten Ausgestaltung der Erfindung,
- Fig. 2
- die schematische Darstellung eines Hydraulikkreises gemäß einer zweiten Ausgestaltung der Erfindung und
- Fig. 3
- die schematische Darstellung eines Hydraulikkreises gemäß einer dritten Ausgestaltung der Erfindung.
- Fig. 1
- the schematic representation of a hydraulic circuit according to a first embodiment of the invention,
- Fig. 2
- the schematic representation of a hydraulic circuit according to a second embodiment of the invention and
- Fig. 3
- the schematic representation of a hydraulic circuit according to a third embodiment of the invention.
Unter dem Bezugszeichen 10 ist in der Fig. 1 ein geschlossenes Hydrauliksystem (Closed-Center-Hydraulic-System) dargestellt, wie es beispielsweise bei einem nicht dargestellten landwirtschaftlichen Schlepper Verwendung finden kann. Der dargestellte Teil des Hydrauliksystems enthält eine Pumpe 12 und einen Sumpf oder Reservoir 18. Die Pumpe 12 erzeugt in der Pumpenausgangsleitung 14 einen Flüssigkeitsdruck, der von einem an dem Lastmeldeanschluß 16 anstehenden Lastdruck abhängt. Ferner enthält das dargestellte Hydrauliksystem 10 ein pilot-, servo- oder magnetspulenbetätigtes Steuerventil 20, durch welches die Verbindungen zwischen der Pumpe 12, dem Sumpf 18 und einer Hydraulikfunktion steuerbar ist. Bei der Hydraulikfunktion handelt es sich beispielsweise um einen Hydraulikzylinder 22 eines nicht dargestellten Anbaugeräts, das an den Schlepper montierbar ist. Das dargestellte Steuerventil 20 wird magnetspulenbetätigt. Die Erfindung läßt sich jedoch auch mit einem durch Hydraulikflüssigkeit oder Luftdruck pilotgesteuerten Ventil ausführen. Das Steuerventil 20 kann sowohl auf dem Schlepper als auch auf dem Anbaugerät installiert sein. Das Hydrauliksystem 10 kann auch weitere, nicht dargestellte servo- oder handbetätigbare Steuerventile zur Beeinflussung zusätzlicher Hydraulikfunktionen enthalten. Der Pumpenanschluß des Steuerventils 20 ist über die Leitung 26 und Verbindungsglieder 24 an die Pumpenausgangsleitung 14 angeschlossen. Der Rücklaufanschluß des Steuerventils 20 steht über die Leitung 30 und Verbindungsglieder 28 mit dem Sumpf 18 in Verbindung. Das Hydrauliksystem 10 des Schleppers kann ferner ein Verbindungsglied 32 sowie eine Leitung 34 enthalten, die über ein Wechselventil 36 mit dem Lastmeldeanschluß 16 in Verbindung stehen. Im vorliegenden Ausführungsbeispiel ist jedoch das Verbindungsglied 32 geschlossen und unbenutzt. Andere Teile eines Schlepperhydrauliksystems 38 sind mit dem dargestellten Hydrauliksystem 10 über die Pumpenausgangsleitung 14, eine Lastmeldeleitung 37 und eine Rückführleitung 39 verbunden.1, a closed hydraulic system (closed center hydraulic system) is shown in FIG. 1, as can be used, for example, in an agricultural tractor, not shown. The part of the hydraulic system shown contains a
Gemäß vorliegender Erfindung weist ein magnetspulen- oder servogesteuertes Zuflußsteuerventil 40 ein Gehäuse auf, in dem sich ein erster Anschluß 42, der mit der Pumpenausgangsleitung 14 verbunden ist, ein zweiter Anschluß 44, der über das Wechselventil 36 mit dem Lastmeldeanschluß 16 verbunden ist, und ein dritter mit dem Sumpf 18 verbundener Anschluß 46 befinden. Das Zuflußsteuerventil 40 enthält ein Ventilteil 48, das sich zwischen einer ersten Stellung und einer zweiten Stellung verschieben läßt. In der ersten, dargestellte Stellung ist der erste Anschluß 42 gesperrt und der zweite Anschluß 44 mit dem dritten Anschluß 46 verbunden. In der zweiten Stellung wird der erste Anschluß 42 mit dem zweiten Anschluß 44 verbunden und der dritte Anschluß 46 gesperrt. Eine Feder 50 ist vorgespannt und drängt das Ventilteil 48 in seine erste Stellung. Eine Servovorrichtung 52, wie beispielsweise eine Magnetspule, ist erregbar, um das Ventilteil 48 in seine zweite Stellung zu bewegen.According to the present invention, a solenoid-controlled or servo-controlled
Jede der Magnetspulen des Steuerventils 20 wird vorzugsweise durch einen Ventiltreiber 60, wie er beispielsweise durch die US-A-4,964,014 beschrieben wurde, angesteuert. Die Ventiltreiber 60 ihrerseits können durch eine elektronische Steuereinheit 62, wie sie beispielsweise durch die US-A-4,518,044 beschrieben wurde, angesteuert werden. Die beiden Ventiltreiber 60 werden über einen stromfühlenden Widerstand R1 von einer Batterie 64 mit Strom versorgt. Wird einer oder beide der Ventiltreiber 60 erregt, so reagiert ein Vergleichskreis 66 auf den sich über dem Widerstand R1 ausbildenden Spannungsabfall und erregt die Spule 52 des Zuflußsteuerventils 40. Hierdurch wird das Ventilteil 48 immer dann in seine zweite Stellung verschoben, wenn wenigstens eine Spule des Steuerventils 20 erregt wird. Das Ventilteil 48 bleibt jedoch in seiner ersten Stellung, wenn keine der Spulen des Steuerventils 20 erregt ist.Each of the solenoid coils of the
Immer wenn wenigstens eine der Spulen des Steuerventils 20 aktiv ist, verbindet das Zuflußsteuerventil 40 die Pumpenausgangsleitung 14 mit dem Lastmeldeanschluß 16, so daß die Pumpe 12 des Hydrauliksystems 10 sich auf maximalen Ausgangsdruck einstellt. Durch diese Ausbildung läßt sich eine hohe Durchflußleistung an das Steuerventil 20 und den Hydraulikzylinder 22 des Anbaugeräts erreichen. Es ist dabei lediglich ein kleines Zuflußsteuerventil 40 erforderlich, das auf niedrigem elektrischen Leistungsniveau betrieben werden kann, da es lediglich ein Lastmeldesignal mit niedriger Durchflußmenge an die Pumpe 12 liefern muß, um einen maximalen Pumpenausgangsdruck zu erzeugen.Whenever at least one of the coils of the
Das in Fig. 1 dargestellte Hydrauliksystem 10 steuert hohe Drücke nur dann, wenn der Hydraulikzylinder 22 des Anbaugeräts betätigt wird. Dabei liefert die Pumpe 12 lediglich die erforderliche Flüssigkeitsmenge. Eine solche Ausführung ist besonders dort vorteilhaft, wo Anbaugeräte mit mehreren Funktionen, die intermittierend betätigbare Hydraulikzylinder enthalten, verwendet werden. Andernfalls wären ein erheblicher Installationsaufwand oder Ventilmodifikationen zur Erzeugung eines Lastmeldesignals erforderlich, so daß ein Verwender eher ein Anbaugerätesteuerventil verwenden und den Schlepper bei ständig hohem Systemdruck betreiben würde. Es ist grundsätzlich jedes elektrohydraulische Ventil des Schleppers verwendbar, um die Flüssigkeitsdruckverbindung zu dem Lastmeldeanschluß 16 der Pumpe 12 zu steuern. Es ist, wie später im einzelnen beschrieben wird, auch möglich, hier das schleppereigene Hubwerkssteuerventil zu verwenden.The
Die Fig. 2 zeigt ein zweites Ausführungsbeispiel, bei dem das Zuflußsteuerventil 40 durch ein Hubwerkssteuerventil 70 ersetzt wurde. Das Hubwerkssteuerventil 70 enthält ein Gehäuse mit einem ersten Anschluß 72, der mit der Pumpenausgangsleitung 14 verbunden ist, einen zweiten Anschluß 74, der über ein Wechselventil 36 mit dem Lastmeldeanschluß 16 der Pumpe 12 verbunden ist, einen dritten Anschluß 76, der mit dem Sumpf 18 verbunden ist, einen vierten Anschluß 78, der mit Hydraulikzylindern 80 verbunden ist, und einen fünften Anschluß 82, der sowohl mit dem Lastmeldeanschluß 16 als auch mit dem zweiten Anschluß 74 verbunden ist.FIG. 2 shows a second exemplary embodiment in which the
Das Hubwerkssteuerventil 70 enthält ein Ventilteil 71, das sich in die dargestellte erste, neutrale Stellung bewegen läßt, in der der erste Anschluß 72, der vierte Anschluß 78 und der fünfte Anschluß 82 gesperrt sind und der zweite Anschluß 74 mit dem dritten Anschluß 76 verbunden ist. In einer zweiten (Hebe-) Stellung des Ventilteils 71 sind der erste Anschluß 72 mit dem fünften Anschluß 82 und der zweite Anschluß 84 mit dem vierten Anschluß 78 verbunden und der dritte Anschluß 76 gesperrt. In einer dritten (Senk-) Stellung des Ventilteils 71 sind der erste Anschluß 72 und der fünfte Anschluß 82 gesperrt und der zweite Anschluß 74 sowie der vierte Anschluß 78 mit dem dritten Anschluß 76 verbunden. Das Ventilteil 71 wird durch vorgespannte Federn 84 und 86 in seine erste, neutrale Stellung gedrängt und läßt sich durch erregbare Magnetspulen 88 und 90 in seine zweite bzw. dritte Stellung bringen.The hoist
Bei der Ausbildung gemäß Fig. 2 wird immer dann, wenn eine der Magnetspulen des Steuerventils 20 erregt ist, das Hubwerksventil 70 in seine zweite Stellung bewegt, bei der der Pumpenausgangsdruck an den Lastmeldeanschluß 16 angeschlossen ist, so daß die Pumpe 12 des Hydrauliksystems 10 ihren maximalen Hydraulikdruck aufbaut. Zur gleichen Zeit wird der Pumpenausgangsdruck an die Hydraulikzylinder (Hubwerkszylinder) 80 angelegt, so daß diese voll ausfahren. Hierdurch wird sichergestellt, daß immer dann, wenn das Steuerventil 20 betätigt wird, das nicht dargestellte Hubwerk voll angehoben ist, so daß es nicht den Betrieb des auf dem nicht gezeigten Anbaugerät befindlichen Hydraulikzylinders 22 stört.In the embodiment according to FIG. 2, whenever one of the solenoid coils of the
Das in Fig. 3 dargestellte Ausführungsbeispiel ähnelt dem der Fig. 2. In dem Ausführungsbeispiel der Fig. 3 ist jedoch keine Leitung vorgesehen, durch die der Pumpenausgang unmittelbar mit einem Einlaß des Steuerventils 20 verbunden ist. An Stelle dessen verbindet eine Leitung 92 den vierten Anschluß 78 des Hubwerksventils 70 mit dem Einlaß eines Anbaugerätesteuerventils 20. Bei der Ausbildung gemäß Fig. 3 steuert das Hubwerksventil 70 die Flüssigkeitsverbindung zu dem Lastmeldeanschluß 16 und die Verbindung zwischen der Pumpe 12 und dem Steuerventil 20.The embodiment shown in FIG. 3 is similar to that of FIG. 2. In the embodiment of FIG. 3, however, there is no line through which the pump outlet is connected directly to an inlet of the
Bei den in Fig. 2 und 3 dargestellten Ausgestaltungen können die Hubwerkszylinder 80 auch von dem Hubwerksventil 70 gelöst werden, da sie während des Betriebs des Steuerventils 20 voll ausgefahren bleiben sollen.In the embodiments shown in FIGS. 2 and 3, the lifting
Claims (10)
- Hydraulic system with a pump (12) which provides pressurized fluid at a pump output port as a function of pressure in a load-sensing port (16), a reservoir (18), a hydraulic function (22), a control valve (20) through which, in dependence on control signals, the hydraulic function (22) can be connected as desired either with the pump (12) or the reservoir (18), and a load-sensing valve (40, 70),
characterised in that
through the load-sensing valve (40, 70), the load-sensing port (16) can be acted on either by the output pressure of the pump (12) or by the pressure of the reservoir (18), as desired, and that the load-sensing valve (40, 70) is reversible, in dependence on the control signals given to the control valve (20), in such a way that the load-sensing port (16) is connected with the pump output port (14) when the control valve (20) is activated and with the reservoir (16) when the control valve is inoperative. - Hydraulic system according to claim 1,
characterised in that
the pump output port (14) is directly connected to an inlet of the control valve (20). - Hydraulic system according to claim 1 or 2,
characterised in that
the load-sensing valve (40, 70) contains a valve member (48, 71), which is pushed by a spring (50, 84) into a first position, in which it connects the load-sensing port (16) with the reservoir (18) and which can be moved by means of a servo mechanism against the force of the spring (50, 84) into a second position, in which it connects the load-sensing port (16) with the pump output port (14). - Hydraulic system according to one of claims 1 to 3,
characterised in that
the load-sensing valve (40, 70) has a first port (42, 72) connected to the pump output port (14), a second port (44, 74) connected to the load-sensing port (16), a third port (46, 76) connected to the reservoir (18) and also has a valve member (48, 71) which, in a first position, blocks the first port (42, 72) and connects the second port (44, 74) to the third port (46, 76) and, in a second position, connects the first port (42, 72) to the second port (44, 74) and blocks the third port (46, 76). - Hydraulic system according to one of claims 1 to 4,
characterised in that
the load-sensing valve is a component part of a lifting gear control valve (70) which controls the flow of fluid between the pump output port (14), the reservoir (18) and the hydraulic cylinder (80) of a mounted implement. - Hydraulic system according to claims 4 and 5,
characterised in that
the load-sensing valve (70) has a fourth port (78) connected to the hydraulic cylinder (80) and a fifth port (82) connected to the load-sensing port (16), and in that the valve member (71), in a first position, blocks the first port (72), the fourth port (78) and the fifth port (82) and connects the second port (74) to the third port (76), and, in a second position, connects the first port (72) to the fifth port (82) and the second port (74) to the fourth port (78) and blocks the third port (76). - Hydraulic system according to claim 6,
characterised in that
the valve member (71) can be moved into a third position, in which it blocks the first port (72) and the fifth port (82) and connects the second port (74) and the fourth port (78) to the third port (76). - Hydraulic system according to claim 6 or 7,
characterised in that
the fourth port (78) is connected both to the hydraulic cylinder (80) and to an inlet of the control valve (20). - Hydraulic system according to one of claims 1 to 8,
characterised in that
at least one further hydraulic function (38) is connected to the pump output port (14) and gives a load-sensing signal to the load-sensing port (16) via a load-sensing line (37). - Utility vehicle with a hydraulic system in accordance with one of claims 1 to 9.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US07/923,762 US5245827A (en) | 1992-08-03 | 1992-08-03 | Supply valve arrangement for closed center hydraulic system |
US923762 | 1992-08-03 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0582099A2 EP0582099A2 (en) | 1994-02-09 |
EP0582099A3 EP0582099A3 (en) | 1994-08-24 |
EP0582099B1 true EP0582099B1 (en) | 1997-01-02 |
Family
ID=25449226
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP93110985A Expired - Lifetime EP0582099B1 (en) | 1992-08-03 | 1993-07-09 | Hydraulic system with load sensing |
Country Status (10)
Country | Link |
---|---|
US (1) | US5245827A (en) |
EP (1) | EP0582099B1 (en) |
JP (1) | JPH06159305A (en) |
AT (1) | ATE147139T1 (en) |
AU (1) | AU659751B2 (en) |
BR (1) | BR9303240A (en) |
CA (1) | CA2101235C (en) |
DE (1) | DE59304948D1 (en) |
ES (1) | ES2095527T3 (en) |
MX (1) | MX9304408A (en) |
Families Citing this family (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE4311191C2 (en) * | 1993-04-05 | 1995-02-02 | Deere & Co | Hydraulic system for supplying open or closed hydraulic functions |
DE10040395A1 (en) | 1999-09-14 | 2001-03-22 | Caterpillar Inc | Hydraulic control system for improving pump response and dynamic match of pump and valve has control unit for controlling rate of change of cross-section of main flow control valve |
US20060196179A1 (en) * | 2005-03-01 | 2006-09-07 | Arun Kesavan | Load-sensing integrated brake and fan hydraulic system |
US8267004B2 (en) * | 2009-05-20 | 2012-09-18 | Lifetime Enterprises, Llc | Adaptable hydraulic control system |
CN102734276B (en) * | 2012-06-28 | 2015-07-01 | 三一汽车起重机械有限公司 | Load sensing electric proportion hydraulic control system and engineering machinery |
CN103148038A (en) * | 2013-03-20 | 2013-06-12 | 镇江华瑞液压机械有限公司 | Dual-energy saving combined hydraulic valve |
CN103727082B (en) * | 2013-12-27 | 2016-08-31 | 三一汽车起重机械有限公司 | Hydraulic system and engineering machinery |
CN105158076A (en) * | 2015-08-19 | 2015-12-16 | 河南科技大学 | Impact type pneumatic bearing device |
DE102018212077A1 (en) * | 2018-07-19 | 2020-01-23 | Deere & Company | Method for operating a hydraulic consumer on an electrically actuated control valve |
CN111577689B (en) * | 2020-06-03 | 2021-03-26 | 江苏科迈液压控制系统有限公司 | Flow saturation resisting method for load sensitive proportional multi-way valve |
Family Cites Families (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3486334A (en) * | 1968-05-16 | 1969-12-30 | Cessna Aircraft Co | Hydraulic power transmission control |
US4276811A (en) * | 1972-11-08 | 1981-07-07 | Control Concepts, Inc. | Closed center programmed valve system with load sense |
US4401009A (en) * | 1972-11-08 | 1983-08-30 | Control Concepts, Inc. | Closed center programmed valve system with load sense |
US4050596A (en) * | 1975-07-24 | 1977-09-27 | Control Concepts, Inc. | Electrohydraulic valve assembly for front end loader attachment to farm tractor |
US4046399A (en) * | 1975-11-05 | 1977-09-06 | Control Concepts, Inc. | Electrohydraulic system for towed vehicle |
US4023646A (en) * | 1975-11-24 | 1977-05-17 | Allis-Chalmers Corporation | Load sensitive hydraulic system |
US4107924A (en) * | 1977-04-28 | 1978-08-22 | Caterpillar Tractor Co. | Pump upgrading system |
US4199942A (en) * | 1978-09-28 | 1980-04-29 | Eaton Corporation | Load sensing control for hydraulic system |
DE3318052A1 (en) * | 1982-12-30 | 1984-07-05 | Robert Bosch Gmbh, 7000 Stuttgart | HYDRAULIC CONTROL DEVICE |
US4589437A (en) * | 1983-07-07 | 1986-05-20 | Zeuner Kenneth W | Reel speed valve assembly |
DE3914904C2 (en) * | 1989-05-05 | 1995-06-29 | Rexroth Mannesmann Gmbh | Regulation for a variable displacement pump that works depending on the load |
EP0477370B2 (en) * | 1990-01-11 | 1998-11-04 | Hitachi Construction Machinery Co., Ltd. | Hydraulic valve apparatus |
-
1992
- 1992-08-03 US US07/923,762 patent/US5245827A/en not_active Expired - Lifetime
-
1993
- 1993-07-09 DE DE59304948T patent/DE59304948D1/en not_active Expired - Lifetime
- 1993-07-09 EP EP93110985A patent/EP0582099B1/en not_active Expired - Lifetime
- 1993-07-09 AT AT93110985T patent/ATE147139T1/en not_active IP Right Cessation
- 1993-07-09 ES ES93110985T patent/ES2095527T3/en not_active Expired - Lifetime
- 1993-07-21 MX MX9304408A patent/MX9304408A/en not_active IP Right Cessation
- 1993-07-23 CA CA002101235A patent/CA2101235C/en not_active Expired - Fee Related
- 1993-07-29 AU AU44310/93A patent/AU659751B2/en not_active Ceased
- 1993-07-30 BR BR9303240A patent/BR9303240A/en not_active IP Right Cessation
- 1993-08-03 JP JP5192467A patent/JPH06159305A/en active Pending
Also Published As
Publication number | Publication date |
---|---|
JPH06159305A (en) | 1994-06-07 |
ATE147139T1 (en) | 1997-01-15 |
EP0582099A3 (en) | 1994-08-24 |
DE59304948D1 (en) | 1997-02-13 |
MX9304408A (en) | 1994-03-31 |
CA2101235A1 (en) | 1994-02-04 |
EP0582099A2 (en) | 1994-02-09 |
US5245827A (en) | 1993-09-21 |
CA2101235C (en) | 1995-06-27 |
ES2095527T3 (en) | 1997-02-16 |
AU659751B2 (en) | 1995-05-25 |
AU4431093A (en) | 1994-02-10 |
BR9303240A (en) | 1994-03-15 |
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