WO2014121910A1

WO2014121910A1 - Hydraulic multi-load system with energy-efficient hydraulic circuit

Info

Publication number: WO2014121910A1
Application number: PCT/EP2014/000266
Authority: WO
Inventors: Philip Nagel
Original assignee: Karlsruher Institut für Technologie
Priority date: 2013-02-05
Filing date: 2014-02-03
Publication date: 2014-08-14
Also published as: EP2954215A1; DE102013101107A1

Abstract

The invention relates to a hydraulic multi-load system with an energy-efficient hydraulic circuit, comprising a hydraulic source (7) for a volumetric flow rate of a hydraulic medium and comprising at least two loads (1, 2, 3) with control valves (4, 5, 6), each load being connected to the source via a respective feed line (11) and a respective return line (12). The aim of the invention is to provide a hydraulic multi-load system which does not have additional sensors and which has a reduced energy requirement and produces less lost energy. This is achieved in that at least one hydraulic store (27) or buffer is provided, the store or buffer has a hydraulic connection to at least one return line, and at least one return line has means for diverting hydraulic medium into the store or the buffer.

Description

Hydraulic multi-user system with energy-efficient hydraulic circuit

The invention relates to a hydraulic multi-user system, in particular a constant-pressure system or load-sensing system with energy-efficient hydraulic circuit for reducing energy losses according to the first claim.

In the field of hydraulic drive technology for mobile and stationary machines, multi-user systems in which several consumers (rotational, translational) are supplied with a smaller number of hydraulic sources (hydraulic pumps, storage) are common (see [1-4]). Usually several consumers are always connected to a common source and are supplied by them. The load and thus the demand for hydraulic power of the individual consumers is not only dependent on their maximum force, but also on the particular application. It varies constantly. The individual consumers connected to one hydraulic source usually differ in their respective load from those of the other consumers. However, a hydraulic source must always maintain a maximum pressure required for the most heavily loaded consumer, i. an energy surplus is always generated which is not needed by the low-load consumers. Energy losses are constantly generated. This is due to the fact that the source can promote the hydraulic medium (usually hydraulic oil) physically only with a potential (pressure). ■

In. a direct hydraulic connection of multiple consumers to a common hydraulic source, the hydraulic medium would follow the path of least resistance initially only drive the lower-load consumers. As measures to prevent or control different

BESTÄTlGUNGSe ^ DPFE more parallel operated consumers of this effect controllable hydraulic resistors (control valves) are provided at each consumer, which throttles the uniform pressure of the hydraulic source to the pressure required at each consumer. When throttling a pressure energy losses always occur, namely on all available on the market and below hydraulic circuits (eg

Closed center, open center, load sensing with upstream or downstream pressure compensators, total flow control).

A general aim is to reduce the above-mentioned systemic energy losses in multi-consumer systems and thus the required energy intake, in particular to counteract increasingly stringent emissions standards and rising raw material prices for ^' fuel. For this the following concepts are known:

In a constant-current system ("open-center systems", [1]) a hydraulic source delivers a constant volume flow (constant pump) into a circuit to which the consumers are connected depressurized back into the tank When a consumer is activated, the non-pressurized circuit to the tank is partially or completely closed, the inlet to the consumer partially or fully opened

Pressure relief valve limited system pressure. A valve to the consumers is opened, so that the maximum pressure on the pressure of the consumer is reduced. The system works with a volume flow and a pressure surplus.

In constant-pressure systems ("closed-center systems", [1-4]), a source with variable volume flow (variable displacement pumps) is regulated so that a constant system pressure is always present. is ensured. The pressure is preset via a pump controller. The pump controller ensures a system pressure below the pressure of the pressure relief valve, independent of the volume flow. When no consumer is actuated, the pump only delivers as much volume flow in order to compensate for any leakage and losses while maintaining the required pressure. If a consumer is activated, the flow rate of the pump increases, whereby the pressure of the pump is reduced via a valve to the pressure of the consumer. The system ^'operating at a pressure excess, but advantageously not with an additional volume of excess electricity.

Load-sensing systems (see [1-4]) are derived from constant-pressure systems, where, however, the control pressure of the pump (setpoint specification) is not constant _. Pump controller with fixed target specification is given, but by another hydraulic signal circuit .- The highest consumer pressure is identified, and reported to the pump, which is adjustable in their performance accordingly. This reduces systemic losses. The system works with the lowest possible variable and thus an energy-optimized pressure surplus and without excess flow. , .

Load-sensing systems allow precise adjustment of the variable displacement pump and thus of the total pressure, which is based on the highest load of the consumers in the hydraulic system.

STinunenstrom-Regel-Systeme ("flow matching", see [2], [4]). Use as the aforementioned load-sensing systems, a sensor, the volumetric flow demand of a consumer directly by · Measuring the machine operator's desire with a sensor Thus, the pressure of the working pump can be lowered further. tilen before consumers are not thereby reduced. ^'

Based on the above concepts, there are the following approaches to reduce systemic losses by throttling (pressure reduction) on low-load consumers:

A first approach is to divide consumers into several consumer groups with similar load profiles (multi-loop systems). Ideally, each consumer is operated only with a source adapted to it (positive displacement control). Each group is fed by one and each with its own hydraulic source adapted to its load profile. The difference in the energy needs of consumers per source and thus the _. generated energy surplus are thus significantly reduced, the expenditure on equipment by additional groups and thus sources adversely increased.

Further, there is another approach in a series connection of consumers, in which a second consumer can be switched behind a first consumer to supply this with hydraulic medium (preferably hydraulic oil) .. The hydraulic medium is passed in series through several consumers and gradually relaxed (composite principle) ,

Although all of the aforementioned concepts and approaches provide for a load pressure equalization with respect to the hydraulic source, but this is done by valves that convert energy surpluses, into heat and enter in the hydraulic medium no longer usable energy loss.

Based on this, the object of the invention is to provide a hydraulic multi-user system without additional sensors and with further reduced energy requirement and energy loss. proposal to produce, which is characterized by a simple apparatus and does not have the aforementioned disadvantages.

The object is achieved by characterizing features of claim 1. In these backward dependent claims give advantageous embodiments again.

The solution of the task provides, an energy-efficient hydraulic circuit in addition to a Mehrverbrauchersystem described above, preferably a constant-pressure system, more preferably a load-sensing system, in which the feed pressures as possible all connected to a source consumers as close as possible maximum required consumer supply pressure of the most heavily loaded consumer are raised. For this purpose, preferably also consumer feed pressures and the pressure, which is specified by the hydraulic source (system pressure), adapted to each other. An increase in a consumer feed pressure, instead of a throttling of unused pressures in the hydraulic medium in that the consumer a memory or buffer is connected in series, which is converted to another pressure reduction in usable power. A system comprises at least two, preferably three or four consumers.

The system pressure is always greater than the maximum consumer pressure required and exceeds the consumer feed pressure of each

, A consumer pressure is the pressure that must be applied to a consumer in order to make it suitable for the provision of the respective intended consumer service. The . Consumer pressures change with the activation of the consumer continuously during operation.

Preferably, this maximum consumer pressure of the system forms the maximum consumer feed pressure, ^■ as this pressure, in contrast to the consumer feed pressure of the other consumer, rather preferably not raised. The property of the highest loaded consumer can change among the consumers of the system. In contrast to a load-sensing system, the system pressure in a constant-pressure system is not adjusted according to the maximum required consumer supply pressure.

During the passage of the hydraulic medium through the consumer, usually a hydraulic piston or other hydraulic Arbeitsmäschine takes place a pressure reduction, in total equal to the consumer pressure. The pressure difference between system pressure and consumer pressure is the loss pressure. The loss pressure is associated with a power loss. The loss pressure is mainly due to the control valves, which passes through the hydraulic medium before and after passing through the consumer as well as other hydraulic components and resistors such. preferably on upstream pressure compensators. In a load-sensing system with demand-controlled system pressure, the loss pressures generated by throttling bridge only significantly lower pressure differences compared to the conventional constant-pressure system.

An essential feature of the invention is that an existing power surplus (system power minus the consumer power) after leaving the consumer. is not throttled by a pre- or downstream valve by pressure release, ie, as a loss of energy to the hydraulic medium, is transmitted, but is redirected by a hydraulic circuit in a hydraulic accumulator. The hydraulic accumulator is connected in series with the low-load consumers. The memory serves as a buffer; ^'The stored energy can be called up again at a later date. The pressure in the memory is the memory pressure. The hydraulic Mehrverbrauchersystem thus comprises a hydraulic source for a flow rate of a hydraulic medium and at least two consumers with control valve, which are connected via a respective feed line and a return line to the source. Furthermore, the system comprises at least one energy-efficient hydraulic circuit with at least one hydraulic pressure accumulator. The latter is connected hydraulically with at least one return line between the consumer and the source, wherein the diversion into the store via a valve control preferably takes place with at least one diverter valve or at least one shut-off valve. A possible return flow from the reservoir back into the return line is preferably avoided via check valves.

The accumulator pressure raises the level of the consumer pressure without changing the amount. The consumer feed pressure of such a series circuit is summed up by the consumer pressure and the accumulator pressure; he rises with the accumulator pressure. In order to reduce the throttling of the system pressure on the consumer feed pressures and thus the power loss, the consumer feed pressures are increased by the storage pressures and passed to the consumer past residual pressures in the memory 'instead of relaxing by throttling. Power loss is stored in the memory and is therefore available for further utilization. Ideally, the consumer supply pressures of all consumers are after an increase in the lower consumer supply pressures by the accumulator pressure at a level, so that the required pressure losses and thus power losses are kept as low as possible by the control valves.

However, the sum of consumer pressure and accumulator pressure do not exceed the consumer feed pressure of the highest loaded consumer (maximum consumer feed pressure) Series was switched to the memory and at which the system pressure; of a load-sensing system.

The hydraulic multi-user system with energy-efficient hydraulic circuit thus comprises a hydraulic source and at least two consumers with control valve, which are connected via a feed line and a return line to the source. The. For this purpose, the source preferably comprises a hydraulic pump with a tank or another hydraulic pressure source for generating a preferably constant hydraulic medium volume flow (system volume flow Q _Sys t) at constant or variable system pressure p _Sys t. The control valves are preferably in the form of controllable throttles in front of and behind the consumers Arranged feed lines and ^' return lines and are used in particular a reduction of the system pressure on each required for a consumer power consumer pressure. Preferably, a consumer has its own control valve.

In the specific embodiment, the energy-efficient hydraulic circuit comprises at least one hydraulic accumulator (or buffer) for the intermediate storage of pressurized hydraulic medium. For this purpose, the accumulator has a hydraulic connection, preferably a continuous hydraulic line connection to at least one return line, upstream of each return line of each consumer. Further, for the supply of the memory in at least one return line means are provided for the diversion of hydraulic medium in the memory. The reservoir is a hydraulic accumulator which serves as another hydraulic source for at least one other consumer. The diversion means preferably comprise at least one valve.

One embodiment provides for an energy efficient hydraulic circuit which is applied to each of the consumers Detects loss pressures and a memory or buffer between the return lines of the consumer switches back and forth so that the consumer leaving the flow rates are passed with the highest-ever .Leverustdrücken in the memory. Preferably, means are provided which compares the consumer pressures of all consumers in the system and removes the consumer with the highest consumer pressure (not the consumer supply pressure) from the series connection. The memory is charged until the sum of the accumulator pressure and the consumer pressure of the series connections less losses reaches the system pressure.

It is necessary to match the maximum consumer feed pressure to the consumer pressure of the maximum loaded consumer to allow parallel operation of all consumers. Thus, the pressures of the lower-load consumers must be raised to the highest consumer pressure. It is essential that an adjustment of the different consumer pressures not only by upstream throttle valves, but on an increase .des pressure level is realized by the series-connected common memory. Thus, an addition of the accumulator pressure and the consumer pressures of the less loaded consumer to the level of each highest applied consumer pressure (the highest-load consumer). Thus, the consumer pressure of a consumer increases by an amount resulting from the accumulator pressure.

For this purpose, the hydraulic circuit comprises means for diverting H. hydraulic medium in the return line from the consumer to the source, which does not uselessly relieve a still biased hydraulic medium leaving the consumer, but redirects it into the hydraulic accumulator and / or to another consumer. Optionally, no throttle valves are provided for complete relaxation in the return line. Of the . Hydraulic accumulator preferably comprises a closed rigid volume with a connection for the hydraulic medium, which is introduced into these and presses against a gas cushion and this compresses. Of the. Memory is filled by an introduction of hydraulic medium until it settles in the memory with the accumulator pressure an equilibrium state.

The in the memory (or buffer) biased under pressure accumulator hydraulic medium forms retrievable and thus advantageously usable energy. The reservoir is used for further use as a hydraulic source. A prerequisite for this is that the accumulator pressure exceeds the consumer pressure required for further use. Preferably, energy recovery takes place in the system. For this purpose, the following preferred energy uses are proposed:

1. Direct feed to a consumer preferably of the same consumer system with reduced power requirements. As a result, preferably a series connection of two consumers, whereby a time offset between the operation of the consumer is realized by the hydraulic accumulator. Basically, this also includes one

, repeated feeding of a consumer,

2. Infeed into a hydraulic motor for relief,. the drive of the. hydraulic source,

3. Infeed into other actuators or hydraulic components, e.g. Controls, resistors or valves of the consumer system and / or

4. as a hydraulic source of another consumer system with. a lower operating pressure.

The object is thus achieved by a robust hydraulic circuit which caches an amount of energy leaving the consumer for later use, wherein the circuit works hydraulically self-sufficient. and advantageously without additional control technology or sensors.

The invention will be explained in more detail below with reference to exemplary embodiments with figures. Show it

1 shows a schematic representation of a conventional multi-user system,

2 a to c are each a graphical representation (pressure P over volume flow Q) of the power losses of a constant-pressure system (a), a load-sensing system (b) and a load-sensing system with energy-efficient hydraulic Circuit (c),

3 shows a hydraülischen circuit block for Lastdruck-. Increase in the return by means of 3/2-way valve,

4 shows a hydraulic circuit module for increasing the load pressure in the return by means of 2/2-way valve,

5 shows by way of example a schematic representation of a multi-user system with memory as well.

6 shows a schematic representation of a multi-user system with memory and 3/2-way valve on each consumer.

Fig.l is a conventional load sensor system as Mehrverbrauchersystem according to the aforementioned prior art again. In the example, it comprises three hydraulic piston drives as consumers 1, 2 and 3, each with a control valve 4, 5 and 6, a hydraulic source 7 for a volume flow of a hydraulic medium with tank 8, pump 9 and pump drive 10 as ever a supply line 11 from the source to the consumers and one return line 12 from the consumer in the tank.

The control pressure of the pump (target specification) is not specified by a constant pump controller with fixed target specification, but is controlled by a further hydraulic signal circuit 13 with pressure relief valve 14 and return 15 in the tank.

Furthermore, the illustrated load-sensor system has check valves 20 between the inlets of the consumers 1 to 3, which forwards the maximum consumer pressure retrieved by the consumers hydraulically via a pressure relief valve line 33 to the overpressure valve 14 and thus the system pressure provided by the source via a Actuator 21 for controlling the pump forwards. The consumer pressure is preferably tapped in front of the respective consumers upstream individual pressure compensators 22, 23 and 24 and / or on the control valves 4, 5 and 6. The necessary connection lines are shown in Fig.l dashed lines.

In a constant-pressure system eliminates the aforementioned needs-based readjustment of the system pressure, i. in Fig.l (as well as in Figures 5 and 6) shown in phantom lines and the check valves accounts for otherwise unchanged circuit.

FIGS. 2a to c illustrate graphically the integral performances in a constant-pressure system (a), a load-sensing system (b) and a load-sensing system with energy-efficient hydraulic circuit (c) in a representation of the pressure p via the volume flow Q. The output is calculated from the product of the pressure and the volume flow. The maximum possible The volume flow and pressure of the source are indicated in the diagrams with Q _max or p _max (basic data of the hydraulic source). Furthermore, three consumer services 16, 17 and 18 are shown in the diagrams, the required pressures change continuously during operation and must be covered by the pump performance. Corresponding to the required consumer services, the system volume flow Q _{syst is} specified and the system pressure p _{syst of} the hydraulic source in the example of a constant-pressure system (FIG. 2 a) fixed or set to a load-sensing system (FIGS. 2 b and c) is set variably. The power loss 19 is calculated from the system power (product of system volume flow and system pressure) minus the respective load power applied. Even if the power loss - as shown in Fig.2b - can be minimized by a maximum of the pressure requested by the consumer readjustment of the system pressure, there is a power loss through the less loaded consumer, which is usually delivered in conventional systems as heat input into the hydraulic medium ,

In the context of the invention, the supply of the consumer is realized by the pump as in the aforementioned constant-pressure system or load-sensing system. However, the return line has means, which instead of a return to the tank, a diversion of the hydraulic medium after leaving the consumer in a memory, when the pressure in the memory is less than the pressure of the recycled hydraulic medium. The accumulator pressure thus assumes the function of a backpressure at the outlet of the consumer, whereby the load pressure at the input of the consumers can be increased by an amount resulting from the accumulator pressure, which otherwise leads to an increased power loss due to their load pressures. The pressure difference applied by the consumers remains the same. A large part of the power loss will be is advantageously converted into stored power 25 (see Fig. 2c).

3 shows the required circuit supplement. The return of the hydraulic medium from the load-sensing system is in the return line 12 after leaving the control valve (4, 5 or 6) in a 3/2-way valve .26 (diverter valve) passed, in which the hydraulic medium either the memory 27th or with the tank 8 is directed. The hydraulic medium must always take the way through the diverter valve after leaving a consumer. Preferably, a diverter valve is provided for each consumer, which is preferably connected to a common memory. If the pressure of the hydraulic medium in the area in front of the 3/2-way valve is higher than the internal pressure of the reservoir Ps _pe ic _h e _r , preferably the memory is connected in series with the consumer. To avoid a storage discharge by a reflux of the storage medium back into the diverter valve, a check valve 28 is provided as a safety valve '.

Alternatively, a circuit gem. 4, in which as means for the diversion of hydraulic medium in the memory by a 2/2-way valve 29 (shut-off valve) is realized and the memory preferably always. hydraulically connected to the return line 12. The branching from the return line takes place before the arrangement of the 2/2-way valve. After leaving a consumer, the hydraulic medium only has to pass through the shut-off valve when it is forwarded to tank 8. The shut-off valve is preferably closed when the pressure applied in the hydraulic medium in the return line 12 is greater than the accumulator pressure. It is preferably opened only when the aforementioned switching condition is no longer met, ie the memory is not fillable. The 2/2-way valve prevents unimpeded drainage of prestressed hydraulic fluid in the tank 8. To avoid a memory discharge by a reflux of the storage medium back into the return line 12, a check valve 28 is provided as a safety valve.

Only when the maximum consumer power is always retrieved only from one consumer and exceeds the consumer services of other consumers of the multi-consumer system, a supply of the memory of this consumer with maximum consumer performance, especially in a system pressure readjusting load-sensing system is not expected; Means for diverting hydraulic medium into the memory are optionally not provided for this consumer.

In the circuit designs acc. 3 and 4, the diverter valve 26 and the switching valve 29 are preferably controlled hydraulically, wherein the reduced pressure at the consumer pi (=

Consumer pressure) plus the storage pressure pspeicher the system pressure psyst (= load-sensing pressure P _LS according to Figures 3 and 4). All said pressures are preferably supplied hydraulically to the diversion means, from hydraulic medium to the reservoir or buffer. Basically, the necessary switching condition for a deflection of hydraulic medium in the memory, that the sum of the consumer ^' degraded pressure pi and the accumulator pressure Psticher less system pressure Psyst (alternatively - as shown in Figure 6 - of the consumers retrieved maximum consumer pressure is:

Pi + Pspeicher <Psyst. (1)

If differential cylinders are operated in the hydraulic drive system, two piston surfaces act against each other. These piston surfaces may differ, for example due to a piston rod arranged only on one side. In this case, one of the piston surface is reduced around the piston cross section, whereby the accumulator pressure due to a Kolbenflächenverhältnis- This is not equal to 1 effective to the pump acting depending on the direction of movement of the piston is increased or decreased. This can be taken into account in the setting, in particular, of the means for deflecting, in particular the deflecting valves according to the aforementioned formula (1). Following the deflection into the memory only in a direction of movement of the piston, a fixed adjustment of the deflection is proposed with consideration. If both directions of movement of the piston are used in a memory charging, depending on the direction of movement is an adjustment via a switchable. Back pressure ^■ z. B. above. an additional valve circuit proposed on the opposite valve spool side.

The means for the diversion of hydraulic medium in the memory as the. Shut-off valves and deflection valves are advantageously controlled only hydraulically and regulated. Additional sensors or electronic control of these means are basically not required and preferably not available.

5 shows schematically a load-sensing system with upstream individual pressure car of conventional design (see Fig.l),., Supplied by a memory 27, which can be fed via the return line 12 as in the aforementioned manner. The means for diverting hydraulic medium into the reservoir or buffer, e.g. Circuits with 3/2 or 2/2-way valves which can be used for this purpose (compare FIGS. 3 and 4) are shown in the schematic

Fig.5 not shown explicitly, but provided. Via a drain line 30, the hydraulic medium stored in the memory is led into an optional return valve 31 and passed to a consumer, in the example of the pump drive 10 as needed and / or above a certain pressure. A check valve 32 prevents a direct forwarding into the tank 8 when a pressure difference, which can preferably be set, is exceeded. In contrast to the embodiment shown in FIG. In the embodiment shown in FIG. 5, the check valves 20 and the overpressure valve line 33 (load-sensing line, load-signaling line) are taken into account because of the switchable series connection of storage and consumer, the consumer pressures raised by the accumulator pressure. It is not the consumer pressures compared alone or out, but the respective applied maximum consumer pressure of the maximum loaded consumer against the lower consumer pressures plus the accumulator pressure.

FIG. 6 discloses the embodiment shown in FIG. 5, in which each of the three consumers 1 to 3 is equipped with one respective own 3/2-way valve 26 in the return lines 12 shown in FIG. Each 3/2-way valve is switched via a hydraulic adjustment. The according to the realization of the switching condition. abovementioned formula (1) for the 3/2-way valve required pressures are the consumer demanded maximum consumer pressure, which is tapped hydraulically on the pressure relief valve line 33, the. at the drain line 30 tapped storage pressure and the consumer per consumer between the respective control valve 4-6 and the check valves 20, abgegeriffenen consumer pressure. Instead of the maximum consumer pressure, another embodiment provides a tapping, not shown in the figures, of the system pressure Ps _ys t mentioned in formula (1) at the feed line 11 between the pump 9 and the individual pressure _compensators 22 to 24.

Possible power flow streams in the hydraulic circuit from the pump 9 of the source to the consumer 1-3 and back to the tank 8 of the source of the embodiment illustrated in Fig. 6 are as follows. Starting from the pump 9, the hydraulic medium is conducted through the feed line 11 to the three consumers 1 to 3, whereby, after branching into three consumer paths, there is one individual pressure balance 22 to 24 and one control pressure each. he valve 4 to 6 happens. In the consumer, a relaxation of the hydraulic medium takes place by a pressure difference in the amount of the consumer pressure. From the consumer forwarding via the return line 12 via the control valves 4-6 to the respective consumer assigned 3/2-Wegeven- valves 26 takes place in the directional valves, a check of the switching condition in accordance with. Formula (1) in the aforementioned manner. This is followed either by a forwarding via an introduction into the discharge line 30 to the store 27 or directly to another _. Consumers such as a pump piston or a different hydraulic drive, or a back line through another portion of the ^"return line 12 back into the tank 8 (especially in the case of the most heavily loaded load), in which the pump receives 9 hydraulic oil.

With the aid of the aforementioned circuits, the system-related energy losses of all addressed solutions available on the market can be reduced and thus bring about a significant increase in energy efficiency. Here. Only simple, inexpensive standard components are used. The switching decision is made at each consumer independently of the remaining consumers, so that no complex sensor and control circuit is necessary.

Literature:

[1] Finzel, R.: Electro-hydraulic control systems for mobile machines; Dissertation TU Dresden 2010

[2] Djurovic, M .: Energy-saving drive systems for the working hydraulics of mobile work machines, electrohydraulic load sensing; Dissertation TU Dresden 2007

[3] Will. D. et al .: Hydraulics: Basics, Components,

circuits; http: // www. amazon. en / Hydraulic components circuits-Dieter-Will / dp / 3642172423 / ref = pd_sim_sbs_b_l

[4] Fedde, T. : Electrohydraulic demand flow systems using the example of a tractor; Dissertation, TU Braunschweig 2008; https: // www. tu Brunswick. de / imn / institut / f oerderverein / veroef

List of reference numbers:

1 consumer 1

2 consumers 2

3 consumers 3

4 Control valve for consumers 1

5 control valve for consumers 2

6 Control valve for consumers 3

7 hydraulic source

8 tank

9 pump

10 pump drive

11 feed line

12 return line

13 hydraulic signal circuit

14 pressure relief valve

15 return

16 consumer power of the consumer 1

17 Consumer power of the consumer 2

18 Consumer power of the consumer 3

19 power loss

20 check valve

21 actor

22 Individual pressure scale for consumers 1

23 Individual pressure scale for consumers 2

24 Individual pressure balance for consumers 3

25 power loss

26 3/2-way valve

27 memory

28 check valve

29 2/2-egeventil

30 drain line

31 return valve

32 check valve

33 pressure relief valve line

Claims

claims

1 .. Hydraulic multi-user system with .energieeffizienter hydraulic circuit, comprising

a) a hydraulic source (7) for a volume flow of a hydraulic medium,

b) at least two consumers (1,2,3) with control valve

(4,5,6), which are connected via a respective feed line (11) and one return line (12) to the source, characterized in that

c) at least one hydraulic accumulator (27) or buffer is provided,

d) the reservoir or buffer has a hydraulic connection with at least one return line, and e) at least one return line has means for diverting hydraulic medium into the reservoir or buffer.

2. Hydraulic Mehrverbrauchersystem according to claim 1, characterized in that the memory (27) or buffer is a further hydraulic source for at least one further consumer.

3. Hydraulic Mehrverbrauchersystem according to claim 1 or 2, characterized in that the means comprise at least one valve (26, 29).

4. Hydraulic Mehrverbrauchersystem according to claim 3, characterized in that the valve is a diverter valve (26) and forms the hydraulic connection.

5. Hydraulic Mehrverbrauchersystem according to claim 3, da-. characterized in that the valve is a shut-off valve

, '(29) is connected downstream of the hydraulic connection. Hydraulic Mehrverbrauchersystem according to one of the preceding claims, characterized in that between the memory or buffer and the hydraulic connection, a check valve is provided.