EP0719947B1 - Load-sensing Schaltung - Google Patents
Load-sensing Schaltung Download PDFInfo
- Publication number
- EP0719947B1 EP0719947B1 EP95120626A EP95120626A EP0719947B1 EP 0719947 B1 EP0719947 B1 EP 0719947B1 EP 95120626 A EP95120626 A EP 95120626A EP 95120626 A EP95120626 A EP 95120626A EP 0719947 B1 EP0719947 B1 EP 0719947B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- pressure
- load
- force
- working
- valve body
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2221—Control of flow rate; Load sensing arrangements
- E02F9/2225—Control of flow rate; Load sensing arrangements using pressure-compensating valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
- F04B49/08—Regulating by delivery pressure
-
- 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
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
- F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
- F15B11/165—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for adjusting the pump output or bypass in response to demand
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B2205/00—Fluid parameters
- F04B2205/09—Flow through the pump
-
- 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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
- F15B2211/205—Systems with pumps
- F15B2211/2053—Type of pump
- F15B2211/20546—Type of pump variable capacity
- F15B2211/20553—Type of pump variable capacity with pilot circuit, e.g. for controlling a swash plate
-
- 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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
- F15B2211/25—Pressure control functions
- F15B2211/253—Pressure margin control, e.g. pump pressure in relation to load pressure
-
- 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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/305—Directional control characterised by the type of valves
- F15B2211/30525—Directional control valves, e.g. 4/3-directional control valve
-
- 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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/40—Flow control
- F15B2211/405—Flow control characterised by the type of flow control means or valve
- F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable throttles or orifices
-
- 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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/605—Load sensing circuits
- F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
- F15B2211/6054—Load sensing circuits having valve means between output member and the load sensing circuit using shuttle valves
-
- 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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/605—Load sensing circuits
- F15B2211/6058—Load sensing circuits with isolator valves
-
- 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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/67—Methods for controlling pilot pressure
-
- 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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
- F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
Definitions
- the invention relates to a load-sensing circuit according to the preamble of Claim 1.
- load-sensing circuits are known from practice and for example in the "hydraulic training, issued by Mannesmann Rexroth, Drive and control technology in mobile drive machines ", RE 00 315 / 9.82 on page 68 in hydraulic-mechanical design described.
- These known load-sensing circuits are very susceptible to vibration, so that unstable conditions can often occur; aggravating in addition there are the high volume capacities in the relatively large distances between the hydraulic pump and the consumers bridging hoses and especially strong in mobile applications Fluctuations in oil temperature, drive speed and in vehicles such as such as excavators with multiple consumers the movement of changing masses (Boom, stick, spoon).
- Load sensing circuits in electro-hydraulic Execution show a more stable operating behavior, but a considerable one faces greater design effort.
- the volume flow feedback device comprises the first and second measuring surfaces, wherein the first measuring area is larger than the second measuring area. If for example the throttle cross section of the pressure difference between the Working pressure and the load pressure with the flow of a corresponding volume flow generating variable throttle increases and thus this pressure difference is reduced, the control valve controls the hydraulic pump for a longer time Delivery volume and thus larger volume flow until this at the variable throttle the original one, before enlarging the throttle cross section existing pressure difference generated. The larger volume flow accelerates the or the consumer, so that the working pressure and the load pressure in the same Dimensions increase. This increase in pressure creates the different sizes Measuring surfaces a force component corresponding to the measuring surface difference greater hydraulic force of the pressure difference.
- This force component is a measure of the increase in volume flow and thus represents the feedback force represents, which acts against the counterforce, which is preferably the adjusting force is a compression spring.
- the counterforce which is preferably the adjusting force is a compression spring.
- the feedback device ensures that after each adjustment of the hydraulic pump greater or smaller delivery volume the resultant acting on the control valve the feedback force and the counterforce to a smaller or larger value is set.
- the setpoint setting of the Control valve changed so that a new adjustment of the hydraulic pump to an even larger or smaller delivery volume only with a smaller or larger, counteracting pressure difference between the Working pressure and the load pressure can be carried out. It results in in this way a decreasing with increasing funding volume and, conversely, with decreasing delivery volume increasing p-V characteristic curve, the one Load sensing circuit with so-called proportional behavior.
- the feedback device is advantageously as one Flow feedback device designed, being the force generated by the feedback device can be mechanical force.
- the delivery volume feedback device comprises at least one displacement spring, on the actuator adjusting the delivery volume of the hydraulic pump and attacks on the valve body and the action of the latter by the Counterforce with increasing adjustment of the hydraulic pump to a larger or smaller funding volume reduced or increased. In this way a smaller or Larger pressure difference required to turn the hydraulic pump to a larger one or set a smaller delivery volume.
- the invention is between the valve body and a first, double-acting and stationary actuating cylinder, a second, single-acting, from the counterforce towards a fixed stop Actuated actuating cylinder clamped, the actuating piston under the Effect of the working pressure acts on the valve body against the counterforce, the actuating piston of the first actuating cylinder being the working pressure and has measuring surfaces acted upon by the load pressure and under which Effect of the pressure difference between the working pressure and the load pressure above the second actuating cylinder acts on the valve body against the counterforce.
- valve body takes over together with the first actuating cylinder the load-sensing function and, with the second actuating cylinder, pressure control, which is superimposed on the load sensing, i.e. instead of the latter in Function occurs when the hydraulic force enters the second actuating cylinder System stops at the fixed stop.
- the pressure control points when using the delivery volume feedback device the same proportional behavior as the load sensing control.
- the characteristics of which approximate a performance hyperbola there is a power regulation instead of the pressure can as well as that of the aforementioned pressure control by simultaneous Use of the volume flow feedback device according to the measurement area difference be modified.
- Figure 1 shows a load sensing circuit for a zero stroke controlled Hydraulic pump 1 adjustable delivery volume V, two in the open circuit consumers 2 connected in parallel, such as two hydraulic motors over two Working lines 3 drives hydraulically.
- the hydraulic pump 1 is with a Drive motor, not shown, mechanically coupled and via a main working line 4 to the two working lines 3 and via a suction line 5 connected to the tank 6.
- One of the consumers 2 leads Return line 7 also to tank 6.
- the hydraulic pump 1 is designed, for example, as an axial piston pump, the Actuator 8 for adjusting its delivery volume V via the piston rod 9 with the actuating piston 10 of a hydraulic cylinder 11 in a differential design is mechanically coupled.
- the actuating piston 10 defines in the hydraulic cylinder 11 with its smaller, circular end face a pressure chamber 12 and with its opposite, larger, circular end face one Pressure chamber 13.
- the pressure chamber 12 is connected via a first signal pressure line 14 the main working line 4 and via a second signal pressure line 15 to the Pressure chamber 13 connected.
- the load sensing circuit consists of a control valve 16 in the second Signal pressure line 15, a volume flow feedback device 17 and each an adjusting throttle 18 in the two working lines 3.
- the control valve 16 which is shown symbolically in FIG. 7, divides the second Signal pressure line 15 in a first, connected to the pressure chamber 12 Signal pressure line section 19 and a second, to the pressure chamber 13 connected signal pressure line section 20. It is considered a throttling 3/2-way valve with a working connection P to the first signal pressure line section 19, a working connection A to the second signal pressure line section 20 and a working connection T to a leading to the tank 6 Relief line 21 formed.
- the valve body 22 of the control valve 16 has at its two ends a first measuring surface MF 1 and a second measuring surface MF 2 .
- the first measuring area MF 1 is larger than the second measuring area MF 2 and defines a working pressure control chamber 23 which is connected to the first signal pressure line section 19 via a working pressure control line 24.
- the second measuring surface MF 2 defines a load pressure control chamber 25, which is connected via a load pressure control line 26 to a shuttle valve 27 in a connecting line 28.
- the connecting line 28 connects those working line sections 3, 29 to one another which are arranged in the flow direction after the adjusting throttles 18, ie between these and the consumers 2.
- a preloaded compression spring 30 is arranged in the load pressure control chamber 25, which acts on the valve body 22 in FIG. 1 to the left in the direction of a first working position, in which the working connections A and T are connected to one another, while the working connection P is blocked.
- the volume flow feedback device 17 comprises the two differently sized measuring surfaces MF 1 and MF 2 on the valve body 22 and serves to generate a feedback force F R acting on the valve body, as described below.
- the function of the load-sensing circuit according to FIG. 1 is as follows:
- the zero-stroke-controlled hydraulic pump 1 is actuated by the actuating or working pressure p A, which may be present in the pressure chamber 12 of the hydraulic cylinder 11, and is removed from the main working line 4 via the first actuating pressure line 14.
- p A which may be present in the pressure chamber 12 of the hydraulic cylinder 11
- p A acted upon by a compression spring, not shown, in the pressure chamber 12 in the direction of the maximum delivery volume, as long as the control valve 16 assumes its aforementioned first working position.
- the pressure chamber 13 of the hydraulic cylinder 11 is relieved via the second signal pressure line section 20, the opened working connections A and T of the control valve 16 and the relief line 21 to the tank 6, while the full setting or Working pressure p A builds up and acts on the actuating piston 11 in the direction of its right end position in FIG. 1, which corresponds to the maximum delivery volume V of the hydraulic pump 1.
- the preload (setting force or counterforce F G ) of the compression spring 30 is selected such that it is equal to the hydraulic force of that pressure difference ⁇ p between the working pressure p A of the hydraulic pump 1 which was reduced in front of the adjusting throttle 18 and the load pressure p L of the consumer which was reduced after the adjusting throttle 18 2, which, acting on both measuring surfaces MF 1 and MF 2 of the valve body 22, is formed on the adjusting throttle 18 which is set to the largest throttle cross section and through which the maximum volume flow Q of the hydraulic pump 1 flows; in this case the other adjustment throttle 18 is completely closed.
- the pressure difference ⁇ p increases accordingly and shifts the valve body 22 in FIG. 1 to the right into a second working position, in which when the working connection T is blocked, the working connections A and P are open and the two signal pressure line sections 19 and 20 connect with each other.
- the actuating or working pressure p A now acts on the larger, circular piston surface of the actuating piston 10, thus displacing it to the left in FIG.
- the feedback force F R thus increases the action on the valve body 22 by the counterforce F G and thus sets the control valve 16 to a larger setpoint of the volume flow Q. This results in the pQ characteristic curve shown in FIG. 2, which increases with decreasing volume flow Q and characterizes a proportional operating behavior of the hydraulic pump 1.
- the operating behavior of the hydraulic pump 1 follows the same characteristic curve if the throttle cross section of the variable throttle 18 is increased.
- the pressure difference ⁇ p thus falls, so that the valve body 22 transfers to the first working position and the hydraulic pump 1 is swung out to a larger delivery volume V until it promotes the larger volume flow Q which causes the original pressure difference ⁇ p at the adjusting throttle 18 , ie until force equilibrium is established on valve body 22.
- the larger volume flow Q increases the load on the hydraulic pump 1, so that the working pressure p A and the load pressure p L increase to the same extent.
- the hydraulic force of the working pressure p A acting on the larger measuring surface MF 1 increases by a larger amount corresponding to the measuring surface difference than the hydraulic force of the load pressure p L acting on the smaller measuring surface MF 2 .
- the resulting feedback force F R acts on the valve body 22 in the opposite direction to the counter force F G , whereby the control valve 16 is set to a smaller setpoint of the volume flow Q.
- the result is the same pQ characteristic curve, shown in FIG. 2 and falling with increasing volume flow Q, which characterizes a proportional operating behavior of the hydraulic pump 1.
- Control valve 16 also takes over the function of a Regulation with which the delivery volume V of the hydraulic pump 1 changes Loads are adjusted such that the volume flow Q delivered with the adjusting throttle 18 matches the setpoint.
- the volume flow Q delivered by the hydraulic pump 1 is divided into two partial volume flows, which the consumers 2, in accordance with the set throttle cross sections and the loads acting on the consumers 2 at the branches of the working lines 3 from the main working line 4 drive at appropriate speed.
- the respectively higher load pressure p L acts via the shuttle valve 27 and the load pressure control line 26 on the second measuring surface MF 2 of the valve body 22, while the same working pressure p A in both working lines 3 acts on the first measuring surface MF 1 .
- the smaller of the pressure difference ⁇ p occurring at both adjusting throttles 18 acts on the valve body 22; in other words, the control and regulation described above only controls or regulates the consumer 2 which is subject to greater loads in the manner described above.
- the load-sensing circuit according to FIG. 3 differs from that according to FIG. 1 with an otherwise identical construction and function by an override device 31 for changing the size of the first and second measuring surfaces MF 1 , MF 2 . pressure difference ⁇ p.
- the override device 31 comprises a third measuring surface MF 3 , which is formed on the valve body 22, defines a control pressure chamber 32 and can be acted upon by an external control pressure p S against the counterforce F G of the compression spring 30 via a control pressure line 33 connected thereto, by the pressure difference Increase ⁇ p as required; this function of the override device 31 which causes the hydraulic pump 1 to pivot back to a smaller delivery volume as the control pressure p S increases is also referred to as a negative control function.
- control pressure line 33 can be connected to the pressure space opposite the control pressure space 32, designated by reference numeral 34 in FIG.
- FIG. 4 shows a load-sensing circuit which, instead of the hydraulic override device 31, comprises an override device 35 which is designed as an electrically controllable input part, for example in the form of a switching magnet or control magnet, for the control valve 16 and, with appropriate control, the valve body 22 with a Additional force is applied, which either acts against the counterforce F G of the compression spring 30 (when performing the negative control function) or in the opposite direction (when performing the positive control function).
- an override device 35 which is designed as an electrically controllable input part, for example in the form of a switching magnet or control magnet, for the control valve 16 and, with appropriate control, the valve body 22 with a Additional force is applied, which either acts against the counterforce F G of the compression spring 30 (when performing the negative control function) or in the opposite direction (when performing the positive control function).
- the load sensing arrangement according to FIG. 5 differs from that according to FIG. 1 with otherwise the same construction and function in that instead of the volume flow feedback device 17 with measuring surfaces MF 1 and MF 2 of different sizes, they are of the same size and therefore have the reference symbols MF ' 1 and MF ' 2 designated measuring surfaces and a delivery volume feedback device 36 are used in the form of a displacement measuring spring which acts on the actuator 8 of the hydraulic pump 1 and on the end of the valve body 22 opposite the compression spring 30.
- the measuring spring 36 detects the delivery volume setting of the hydraulic pump 1 by acting on the valve body 22 with increasing delivery volume V with a correspondingly increasing feedback force F R and with decreasing delivery volume V with a correspondingly decreasing feedback force F R against the counterforce F G of the compression spring 30.
- the invention also extends to exemplary embodiments, both the Volume flow feedback device 17 and the delivery volume feedback device 36 use.
- Figure 7 shows a load sensing circuit with superimposed pressure or power control. It comprises a first, double-acting and stationary actuating cylinder 37, a second, single-acting actuating cylinder 38 and the control valve 16 according to FIG. 1, but without the measuring surfaces acted upon by the differential pressure ⁇ p. These are designed as measuring surfaces MF ' 1 and MF' 2 of the same size on the actuating piston 39 of the first actuating cylinder 37.
- the first measuring surface MF ' 1 defines the working pressure control chamber 23, which is connected to the main working line 4 via the working pressure control line 24.
- the second measuring surface MF ' 2 defines the load pressure control chamber 25, which is connected via the load pressure control line 26 to the shuttle valve 27 in the connecting line 28 connecting the working line sections 29.
- the pressure difference .DELTA.p taken off at the adjusting throttle 18 associated with the higher-load consumer acts on the actuating piston 39 of the first actuating cylinder 37 and acts on the second actuating cylinder 38 in FIG. 7 to the left in the direction of the valve body 22 via its piston rod 40.
- the actuating piston 42 of the second actuating cylinder 38 has an annular piston surface 43 which, together with an annular cylinder surface 44 of the same size, defines a likewise annular pressure chamber 45 which is penetrated by the piston rod 46 and is connected to the second actuating pressure line section 15, 20 via a control line 47 ,
- the actuating piston 42 acts on the valve body 22 of the control valve 16 against the counterforce F G of the adjustable compression spring 30 in the direction of the second, under the action of the working pressure p A of sufficient size present in the pressure chamber 45 and taken from the first actuating pressure line section 15, 20 by the first actuating pressure line 14 working position.
- the feedback device is designed here as a delivery volume feedback device 36 which, in the case of the aforementioned pressure control, comprises a position measuring spring and, in the case of the aforementioned power control, an arrangement of a plurality of travel measuring springs connected in series with different characteristic curves which approximate a performance hyperbola.
- the displacement spring or displacement spring arrangement 36 engages on the piston rod 9 of the actuating piston 10 of the hydraulic cylinder 11 and on the end of the valve body 22 opposite the actuating cylinders 37, 38 and acted upon by the compression spring 30.
- the measuring spring or measuring spring arrangement 36 is tensioned with increasing swiveling back of the hydraulic pump 1 to a smaller delivery volume V, so that the resulting feedback force F R acts in the same direction with the compression spring 30, ie the valve body 22 in the direction of the first working position and via this and the actuating piston 42, the second actuating cylinder 38 is urged against a stationary stop 48.
- the valve body 22 takes over together with the first actuating cylinder 37 Load-sensing function and together with the second actuating cylinder 38 Pressure or power control, with the p-V characteristics of both the load sensing control as well as the pressure or power control of the characteristic of Displacement spring 36, for example the characteristic shown in FIG. 6, or the Power hyperbola correspond to the position measuring spring arrangement 36.
- the measuring surfaces MF ' 1 and MF' 2 are larger than the piston surface 43 and the cylinder surface 44, in such a way that during the load sensing function the hydraulic force of the pressure difference ⁇ p acting on the measuring surfaces MF ' 1 and MF' 2 is greater than the hydraulic force of the working pressure p A acting on the cylinder surface 44 and thus keeps the second actuating cylinder 38 at a distance from the fixed stop 46; as a result, the effect of the working pressure p A on the actuating piston 42 and thus the valve body 22 is switched off.
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mining & Mineral Resources (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Fluid-Pressure Circuits (AREA)
- Operation Control Of Excavators (AREA)
- Control Of Positive-Displacement Pumps (AREA)
Description
- Fig. 1
- einen Schaltplan einer Load-Sensing-Schaltung in einer ersten Ausgestaltung nach dem Stand der Technik,
- Fig. 2
- ein Diagramm, das die Kennlinie der Load-Sensing-Schaltung nach Figur 1 zeigt,
- Fig. 3
- einen vereinfachten Schaltplan einer Load-Sensing-Schaltung in einer zweiten Ausgestaltung nach dem Stand der Technik,
- Fig. 4
- einen vereinfachten Schaltplan einer Load-Sensing-Schaltung in einer dritten Ausgestaltung nach dem Stand der Technik,
- Fig. 5
- einen vereinfachten Schaltplan einer Load-Sensing-Schaltung gemäß einem bevorzugten Ausführungsbeispiel der Erfindung,
- Fig. 6
- ein Diagramm, das die Kennlinie der Load-Sensing-Schaltung nach Figur 5 zeigt, und
- Fig. 7
- einen vereinfachten Schaltplan einer Load-Sensing-Schaltung gemäß einem weitere bevorzugten Ausführungsbeispiel der Erfindung.
Claims (9)
- Load-Sensing-Schaltung für eine wenigstens einen Verbraucher (2) über mindestens eine Arbeitsleitung (3) antreibende, nullhubgeregelte Hydropumpe (1) verstellbaren Fördervolumens (V), mit einem auf einen Sollwert des Volumenstroms (Q) der Hydropumpe (1) einstellbaren Regelventil (16), dessen
mit einer Gegenkraft (FG) zur Einstellung des Sollwerts beaufschlagter
Ventilkörper (22) über eine erste Meßfläche (MF1, MF'1) vom Arbeitsdruck (pA) der Hydropumpe (1) gegen die Gegenkraft (FG) in Richtung einer Arbeitsstellung und über eine zweite Meßfläche (MF2, MF'2) vom Lastdruck (pL) des Verbrauchers (2) gleichsinnig mit der Gegenkraft (FG) in Richtung einer anderen Arbeitsstellung beaufschlagbar ist oder dessen mit der Gegenkraft (FG) zur Einstellung des Sollwerts beaufschlagter Ventilkörper (22) über eine an einem Stellkolben (39) wirkende Druckdifferenz (Δp) gegensinnig zu der Gegenkraft (FG) beaufschlagbar ist,
wobei das Regelventil (16) in der einen Arbeitsstellung eine Verstellung der Hydropumpe (1) auf kleineres und in der anderen Arbeitsstellung auf größeres Fördervolumen (V) hervorruft, gekennzeichnet durch
eine Rückmeldeeinrichtung (17, 36) zur Erzeugung einer dem eingestellten Fördervolumen (V) der Hydropumpe (1) entsprechenden und auf den Ventilkörper (22) wirkenden Rückmeldekraft (FR), die die Beaufschlagung des Ventilkörpers (22) durch die Gegenkraft (FG) und damit die Sollwerteinstellung des Regelventils (16) gegensinnig zu Änderungen des Fördervolumens (V) ändert,
wobei die Rückmeldeeinrichtung eine Fördervolumen-Rückmeldeeinrichtung (36) umfaßt, die mit wenigstens einer Wegmeßfeder (36) ausgebildet ist, die an dem das Fördervolumen (V) der Hydropumpe (1) verstellenden Stellglied (8) und am Ventilkörper (22) angreift. - Load-Sensing-Schaltung nach Anspruch 1,
dadurch gekennzeichnet, daß die Kennlinie(n) der Wegmeßfeder(n) (36) einer Leistungshyperbel angenähert ist bzw. sind. - Load-Sensing-Schaltung nach Anspruch 1 oder 2,
dadurch gekennzeichnet, , daß der Arbeitsdruck (pA) in Strömungsrichtung vor und der Lastdrück (pL) in Strömungsrichtung hinter einer Drosselstelle (18) in der Arbeitsleitung (3) abgenommen wird. - Load-Sensing-Schaltung nach Anspruch 3,
dadurch gekennzeichnet, daß die Drosselstelle (18) eine Verstelldrossel ist. - Load-Sensing-Schaltung nach wenigstens einem vorhergehenden Anspruch,
gekennzeichnet durch eine Übersteuerungseinrichtung (31, 35) zum Verändern der Größe der die Meßflächen (MF1, MF2) beaufschlagenden Druckdifferenz (Δp) zwischen dem Arbeitsdruck (pA) und dem Lastdruck (pL). - Load-Sensing-Schaltung nach wenigstens einem vorhergehenden Anspruch,
dadurch gekennzeichnet, daß zwischen dem Ventilkörper (22) und einem ersten, doppeltwirkenden und ortsfesten Stellzylinder (37) ein zweiter, einfachwirkender, von der Gegenkraft (FG) in Richtung eines ortsfesten Anschlags (48) beaufschlagter Stellzylinder (38) eingespannt ist, dessen Stellkolben (42) unter der Wirkung des Arbeitsdrucks (pA) den Ventilkörper (22) gegen die Gegenkraft (FG) beaufschlagt, und daß der Stellkolben (39) des ersten Stellzylinders (37) die vom Arbeitsdruck (pA) und vom Lastdruck (pL) beaufschlagbaren Meßflächen (MF'1, MF'2) aufweist und unter der Wirkung der Druckdifferenz ( Δp) zwischen dem Arbeitsdruck (pA) und dem Lastdruck (pL) über den zweiten Stellzylinder (38) den Ventilkörper (22) gegen die Gegenkraft (FG ) beaufschlagt. - Load-Sensing-Schaltung nach Anspruch 6,
dadurch gekennzeichnet, daß die vom Arbeitsdruck (pA) beaufschlagte Kolbenfläche (43) des Stellkolbens (42) des zweiten Stellzylinders (38) kleiner als die vom Arbeitsdruck (pA) und vom Lastdruck (pL) beaufschlagbaren Meßflächen (MF' 1, MF'2) des Stellkolbens (39) des ersten Stellzylinders (37) ist. - Load-Sensing-Schaltung nach wenigstens einem vorhergehenden Anspruch,
dadurch gekennzeichnet, daß zwischen dem Ventilkörper (22) und einem ersten, doppeltwirkenden und ortsfesten Stellzylinder (37) ein zweiter, einfachwirkender, von der Gegenkraft (FG) in Richtung eines ortsfesten Anschlags (48) beaufschlagter Stellzylinder (38) eingespannt ist, dessen Stellkolben (42) unter der Wirkung des Arbeitsdrucks (pA) den Ventilkörper (22) gegen die Gegenkraft (FG) beaufschlagt, und daß der Stellkolben (39) des ersten Stellzylinders (37) die vom Arbeitsdruck (pA) und vom Lastdruck (pL) beaufschlagbaren Meßflächen (MF'1, MF'2) aufweist und unter der Wirkung der Druckdifferenz (Δp) zwischen dem Arbeitsdruck (pA) und dem Lastdruck (pL) über den zweiten Stellzylinder (38) den Ventilkörper (22) gegen die Gegenkraft (FG ) beaufschlagt. - Load-Sensing-Schaltung nach Anspruch 8,
dadurch gekennzeichnet, daß die vom Arbeitsdruck (pA) beaufschlagte Kolbenfläche (43) des Stellkolbens (42) des zweiten Stellzylinders (38) kleiner als die vom Arbeitsdruck (pA) und vom Lastdruck (pL) beaufschlagbaren Meßflächen (MF' 1, MF'2) des Stellkolbens (39) des ersten Stellzylinders (37) ist.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE4447154A DE4447154C2 (de) | 1994-12-29 | 1994-12-29 | Load-Sensing-Schaltung |
DE4447154 | 1994-12-29 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0719947A2 EP0719947A2 (de) | 1996-07-03 |
EP0719947A3 EP0719947A3 (de) | 1998-02-11 |
EP0719947B1 true EP0719947B1 (de) | 2004-07-21 |
Family
ID=6537452
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP95120626A Expired - Lifetime EP0719947B1 (de) | 1994-12-29 | 1995-12-27 | Load-sensing Schaltung |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0719947B1 (de) |
DE (2) | DE4447154C2 (de) |
Families Citing this family (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19713934B4 (de) | 1997-04-04 | 2004-06-03 | Brueninghaus Hydromatik Gmbh | Lastdruckgeführter Förderstromregler mit Spülkreislauf |
DE10134747B4 (de) * | 2001-07-17 | 2017-05-04 | Liebherr-Machines Bulle S.A. | Verfahren und Vorrichtung zur lastabhängigen Steuerung der Fluidversorgung eines Fluidkreises |
DE10209964A1 (de) * | 2002-03-06 | 2003-09-25 | Zf Lenksysteme Gmbh | System zur Steuerung einer hydraulischen Verstellpumpe |
DE102005016181B4 (de) * | 2005-04-08 | 2018-05-09 | Robert Bosch Automotive Steering Gmbh | Regelvorrichtung für eine hydraulische Fördereinrichtung |
DE102006002959A1 (de) * | 2006-01-21 | 2007-07-26 | Zf Lenksysteme Gmbh | Hydrauliksystem mit volumenstromgeregelter Pumpe |
DE102006014074B4 (de) * | 2006-03-28 | 2017-04-06 | Robert Bosch Gmbh | Dosiersystem und Verfahren zur Abgabe eines Zuschlagstoffes in ein Abgassystem einer Brennkraftmaschine |
DE102007039589A1 (de) * | 2007-08-22 | 2009-02-26 | Voigt, Dieter, Dipl.-Ing. | Regelölpumpe mit verstellwegabhängiger Öldruckregelung |
DE102008031768A1 (de) * | 2008-07-04 | 2010-01-07 | Alpha Fluid Hydrauliksysteme Müller GmbH | Regelanordnung für proportionale Winkelverstellung |
DE102012112879B4 (de) * | 2012-12-21 | 2014-08-07 | Pierburg Gmbh | Ventilvorrichtung für einen Hydraulikkreislauf sowie Ölpumpenregelanordnung |
DE102013216395B4 (de) * | 2013-08-19 | 2019-01-17 | Danfoss Power Solutions a.s. | Steuereinrichtung für hydraulische verstellpumpen und verstellpumpe mit einer steuereinrichtung |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2910611A1 (de) * | 1979-03-17 | 1980-09-18 | Bosch Gmbh Robert | Hydraulikanlage |
DE2913534A1 (de) * | 1979-04-04 | 1980-10-16 | Bosch Gmbh Robert | Einrichtung zur regelung des foerderstroms und zur begrenzung des foerderdrucks einer verstellbaren pumpe |
US4292805A (en) * | 1979-09-24 | 1981-10-06 | Rexnord Inc. | Servo-valve convertible construction |
DE3200885A1 (de) * | 1982-01-14 | 1983-07-21 | Robert Bosch Gmbh, 7000 Stuttgart | Leistungsregler fuer eine hydrostatische pumpe |
DE3340332C2 (de) * | 1983-11-08 | 1988-11-10 | Hydromatik GmbH, 7915 Elchingen | Leistungs-Regelvorrichtung für einen hydrostatischen Antrieb mit Fördermengeneinstellung |
DE3805061A1 (de) * | 1988-02-18 | 1989-08-31 | Linde Ag | Hydraulische schaltanordnung |
DE69314735T2 (de) * | 1992-08-31 | 1998-02-19 | Kayaba Industry Co Ltd | Steuereinrichtung für Verbraucher |
KR0120281B1 (ko) * | 1994-07-29 | 1997-10-22 | 석진철 | 로드센싱시스템의 펌프입력마력 및 유량제어장치 |
-
1994
- 1994-12-29 DE DE4447154A patent/DE4447154C2/de not_active Expired - Fee Related
-
1995
- 1995-12-27 DE DE59510929T patent/DE59510929D1/de not_active Expired - Fee Related
- 1995-12-27 EP EP95120626A patent/EP0719947B1/de not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
DE4447154A1 (de) | 1996-07-11 |
DE4447154C2 (de) | 2002-05-29 |
EP0719947A3 (de) | 1998-02-11 |
DE59510929D1 (de) | 2004-08-26 |
EP0719947A2 (de) | 1996-07-03 |
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