Classifications

• • 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
  • E02F9/2264—Arrangements or adaptations of elements for hydraulic drives
  • E02F9/2267—Valves or distributors
• • 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
  • E02F9/2232—Control of flow rate; Load sensing arrangements using one or more variable displacement pumps
• • 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
  • E02F9/226—Safety arrangements, e.g. hydraulic driven fans, preventing cavitation, leakage, overheating
• • 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
  • E02F9/2264—Arrangements or adaptations of elements for hydraulic drives
  • E02F9/2271—Actuators and supports therefor and protection therefor
• • 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
  • E02F9/2278—Hydraulic circuits
  • E02F9/2296—Systems with a variable displacement 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
  • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
  • F15B11/003—Systems with load-holding 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
  • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
  • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
  • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
  • F15B11/05—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed specially adapted to maintain constant speed, e.g. pressure-compensated, load-responsive
• • 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
• • 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
  • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
  • F15B13/01—Locking-valves or other detent i.e. load-holding devices

Definitions

• the invention relates to a system for load pressure-independent control and load maintenance of a plurality of rotary and / or translational consumers of a construction and / or work machine with at least one regulated pump and at least one secondary pressure compensator containing a spring-loaded control piston.
• the currently known systems of load pressure-independent flow distribution have a functional and spatial separation between the secondary balance, which takes over the function of pressure compensation, signal generation and transmission, and the load holding function.
• the functional and spatial separation of the functional units increases the number of individual components of the system and thus also the cost, assembly and maintenance effort.
• DE 34 43 354 AI describes a hydraulic system which has a pump, for example driven by a diesel engine, which supplies pressure medium to consumers via directional valves.
• the speed controller of the injection pump of the diesel engine is influenced with the aid of a pressurized actuating cylinder, to which the pressure generated in order to increase the speed of the internal combustion engine acts in a control line.
• This pressure is created in cooperation with one of the directional valves for an easily Kenden consumers and a pressure control valve controlled so that a constant pressure is generated in the line when operating a conventional directional valve.
• a special control edge comes into effect, as a result of which a pressure in the line which increases in proportion to the deflection of the control slide is generated.
• the speed of the internal combustion engine and thus of the pump is increased and adjusted so that the consumer just receives the required amount of pressure medium. In this way, economical operation is possible.
• LSC Linde Synchro Control
• the system works according to the load sensing Principle. It significantly improves the simultaneous operation of various functions of hydraulic systems with an open circuit.
• the Linde Synchro Control (LSC) valves are individual valve sections. The suitable combination for different machines is achieved by mounting the individual sections on appropriate valve plates. These valve plates only contain the connection channels, such as the input channel from the pump, connection channels to and from the valves, the return line and the connection of the return to the tank.
• the actual functional elements are housed in the valve sections.
• the valves themselves are piston-type, have a spring-centered closed center position and are operated hydraulically.
• the maximum piston stroke is adjustable, and since the pressure drop at the control edges is kept constant, this means that the maximum oil flow that is to flow through the valve can be limited at the end stops of the valve.
• a pressure compensator is arranged inside the valve piston.
• the shuttle valves for the LS signal are located inside the pressure compensators and move with them into the valve piston.
• EP 0 326 150 AI A generic control system for load pressure independent control of several consumers of a mobile hydraulic construction machine is known from EP 0 326 150 AI.
• This Control system has a pressure compensator containing a spring-loaded control piston.
• a load holding or lowering brake valve in which the components generating the load holding function and control elements are provided in the area of the control piston.
• the object of the invention is to optimize the functional separation between the signal generation, the load holding and the pressure compensation function realized in the current systems by reducing external individual components in order to bring about a cost-effective, assembly-friendly and trouble-free construction.
• Such systems are used for load pressure-independent control and regulation of consumer speeds in mobile construction and work machines, e.g. Excavators, wheel bearings, graders and the like. where at least two consumers, e.g. Hydraulic cylinder, must have a working movement uninfluenced by the load pressures impressed from the outside without mutual interference.
• the lower housing part is part of the control valve.
• a secondary pressure compensator with a load holding function is used, in which, contrary to the function in conventional load compensators with a separate load holding function, the load pressure-carrying signal in the consumer-side channels is not used for forwarding to the pressure regulator of the feed pump, since it thereby means that additional load-holding valves are arranged in the consumer channels an unintentional drop in the load due to the leakage of the pressure regulator of the feed pump or the pressure relief valve of the load-sensing line. According to the invention, this is avoided by reporting a pressure signal to the pressure regulator of the feed pump and to the compensators of the consumers with lower loads, which pressure signal is generated and maintained by the pump itself and the pressure level of which corresponds to the highest consumer pressure.
• FIG. 1 is a schematic representation of a secondary pressure compensator with an integrated load holding function
• 2 shows a schematic control concept for two translational consumers
• 3 shows an embodiment of a secondary pressure compensator with an integrated load holding function
• Fig. 4 shows an embodiment of a control system with two translational consumers and in
• FIG. 1 the schematic structure of a control system according to the invention is shown using the example of a consumer.
• the secondary pressure compensator with load holding function is divided into two components, namely an upper housing part 78 and a lower housing part 86.
• the lower housing part 86 is preferably part of the control valve 7, 8, 9, i.e. forms a uniform housing with it.
• FIG. 2 shows an example of the structure of the control system for two translational consumers 16, 17 (hydraulic cylinders).
• the system accordingly has two secondary pressure compensators, the housings of which are each divided into two housing parts 78, 79 and 86, 87, ie the design of the second secondary pressure compensator corresponds to that of the secondary pressure compensator 78 shown in FIG. 1,
• the control concept is as follows: A pump 1 generates a pressure level in the system that by a preselectable control difference ⁇ p LS above the input pressure signal of the pressure regulator 2 of the pump 1 lies. This pressure level is present when the inlet throttle 7 is open under the piston crown 37 of the first secondary pressure compensator 78, 86.
• the inlet pressure level of the pressure regulator 2 in the line 20 drops via a load-sensing bypass valve 3 to the tank pressure level p r .
• the outlet throttle 9 is opened.
• the consumption-side pressure signal p L1 is present in the discharge channel 22 of the secondary pressure compensator 78, 86 and is planted via the channel 29, a shuttle valve 32, a channel 31 and a damping nozzle 30 except for the the loaded piston head 27 of the secondary pressure compensator 78, 86.
• the consumer-side pressure signal p L1 which acts on the spring-loaded piston head 27 of the secondary pressure compensator 78, 86, keeps the two-part control piston 72, 73 on its valve set 36, as a result of which no leakage flow can escape from the pressure-carrying consumer-side channel 22 into the inlet channel 33.
• the inlet throttle 7 also opens with a corresponding phase shift, as a result of which the pump pressure p p , which is initially at the level of the control pressure difference ⁇ p LS , builds up on the active surface of the piston head 37.
• the seat valve seats 36, 53 of the piston heads and the piston heads 27, 44 of the two-part control pistons of the secondary pressure compensators 78, 86 and 79, 87 are surface-balanced.
• the pressure signal limited to the consumer load pressure p L1 is forwarded to the pressure regulator 2 of the pump 1.
• the pump 1 supplies an output pressure p p which is the preselected one in relation to the pressure input signal in line 20 Control difference ⁇ p LS has.
• the valve seat 36 of the two-part control piston 72, 73 of the secondary pressure compensator 78, 86 opens as a result of the excess pressure on the piston crown surface 37, causing a Volume flow Q V1 flows through the inlet throttle 7, the open valve seat 36 and an outlet throttle 9 to the consumer 16.
• the resulting volume flow Q V1 is determined by the variable opening cross-section A D1 of the inlet throttle 7 and the differential pressure ⁇ P LS - P FI dropping over it in accordance with the following equation:
• the pump pressure signal present in the channel 35 and limited to the consumer pressure level p L1 is forwarded via the check valve 34, the channel 25 and the lines 4, 5 to the second secondary pressure compensator 79, 87.
• the load pressure signal p L1 is present in the pressure signaling line 5 of the secondary pressure compensator 79, 87, which becomes active via the channel 42, the shuttle valve 49, the channel 48 and the damping nozzle 47 on the active surface of the control piston head 44 and thus the Valve seat 53 of the two-part control piston 74, 75 holds securely closed.
• Case III The consumer 16 actuated first has a load pressure p L1 which is lower than that of the consumer 17 subsequently actuated with the load pressure p L2 (p L1 ⁇ p L2 ).
• the load pressure signal p L1 is present in the pressure signaling line 5 of the secondary pressure compensator 79, 87, which becomes active via the channel 42, the shuttle valve 49 and the channel 48 on the active surface of the control piston head 44 and thus the valve seat 53 of the two-part Control piston 74, 75 holds securely closed.
• the outlet throttle 12 is first opened, as a result of which the load pressure p L2 takes effect via the channel 46 in the lower chamber of the shuttle valve 49. Since it is presupposed that p L1 ⁇ p L2 , the load pressure p L2 predominates in the lower chamber of the shuttle valve 49 and acts via the channel 48 and the damping nozzle 47 on the head 44 of the two-part control piston 74, 75.
• the inlet throttle 10 With the transverse cut A D2 open.
• the pressure potential p L1 + ⁇ p LS offered by the pump 1 becomes effective under the piston crown 54 of the two-part control piston 74, 75 of the pressure compensator 79, 87. Since the sum of the current load pressure p L2 and equivalent pressure p F2 of the spring acting on the piston head 44 is greater than the pressure signal p L1 + ⁇ p S which acts on the piston head 54 from the pump 1, the valve seat 53 of the two-part control piston 74, 75 remains initially closed.
• the pump pressure signal p L1 + ⁇ p S is forwarded via the nozzle 38, the check valve 51 and the load signal line 42 and 5 to the pump regulator 2, which then reacts with a pressure increase in the pump outlet pressure p p in line 19.
• the pressure in the line 51 and in the load signaling line 42 can at most reach the load pressure level p L2 , since this leads to the opening of the check valve 40 and thus to the connection to the load-carrying consumer channel 46 and 39, respectively.
• the load pressure signal p L2 also forwarded to the secondary pressure compensator 78, 87 of the consumer 16. Since it is assumed that P L2 > Pn, the load signal p L2 also acts on the piston head 27 of the two-part control piston 72, 73 of the secondary pressure compensator 78 via the channel 25, the shuttle valve 32, the channel 31 and the damping nozzle 30.
• the increased pressure signal of the pump 1 acts on the effective surface of the piston head 37 of the secondary pressure compensator 78, 86, which in turn sets the constant pressure drop ⁇ p LS -p F1 via the inlet throttle 7.
• control concept shown is thus able to keep the consumer speeds preselected via the inlet throttles 7, 10 constant, regardless of the load pressures present in each case.
• the secondary pressure compensators 78, 86 and 79, 87 shown contain, in addition to the load holding function, all signal-generating and signal-comparing functions, as a result of which no external logic elements, such as check valves or shuttle valves, are necessary.
• the poppet valve function integrated in the two-part control pistons 72, 73 and 74, 75 realizes the load holding function often required with mobile hydraulic construction and work machines without additional external components.
• FIG. 3 shows an exemplary embodiment of a single secondary pressure compensator 78, 86 which essentially contains the following components: a two-part control piston 72, 73 which contains a piston crown 37 and a piston head 27, a spring 28 being provided in the region of the piston head 27.
• the pressure signal of the pump not shown, is passed on to the pressure regulator of the pump via the inlet nozzle plate 21, the check valve 34 and the channel 25. Further channels 26, 29, 31 are provided in the area of the housing head of the illustrated secondary pressure compensator 78, 86.
• FIG. 4 shows an exemplary embodiment with two secondary pressure compensators 78, 86 and 79, 87 with two consumers 16, 17.
• FIG. 5 uses a diagram to show the opening characteristic of the outlet throttle in relation to the inlet throttle, the phase shift also being shown as a function of the parameters specified.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mining & Mineral Resources (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Mechanical Engineering (AREA)
• Fluid-Pressure Circuits (AREA)
• Operation Control Of Excavators (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=7845583

Family Applications (1)

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Citations (6)

Family Cites Families (4)

• 1997
  • 1997-10-15 DE DE19745489A patent/DE19745489B4/de not_active Expired - Fee Related
• 1998
  • 1998-09-30 JP JP2000516113A patent/JP2001520335A/ja not_active Withdrawn
  • 1998-09-30 DE DE59804000T patent/DE59804000D1/de not_active Expired - Fee Related
  • 1998-09-30 WO PCT/EP1998/006215 patent/WO1999019571A1/de active IP Right Grant
  • 1998-09-30 EP EP98961094A patent/EP1023508B1/de not_active Expired - Lifetime

Patent Citations (6)

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