DE102008038793A1 - Two-circuit hydraulic system and method for controlling consumers of a dual-circuit system - Google Patents

Abstract

Disclosed are a hydraulic dual-circuit system for controlling consumers and a method for driving consumers of a hydraulic dual-circuit system, wherein the two circuits are connected to each other via a Verschschaltventilanordnung so that the variable displacement of one circuit accumulates pressure medium in the other circle. The two-circuit system has a deactivation device, via which the summation is deactivated when the pressure medium requirement in the connected circuit is smaller than the maximum pump delivery flow and greater than a switching pressure medium demand. This may for example be about 80% of the maximum pump delivery rate.

Description

The The invention relates to a hydraulic dual-circuit system according to the Preamble of claim 1 and a method for driving of consumers of such a two-circuit system.

In the US 6,170,261 B1 is a hydraulic dual-circuit system of a mobile working device, such as a chain or tracked device disclosed. In such caterpillars, the chassis has two chains, which are each controlled separately via one of the hydraulic circuits. To the two hydraulic circuits of the chain unit are also still a slewing gear and units of equipment, such as the boom, the dipper and the spoon connected. Each of the two hydraulic circuits is fed by its own variable displacement pump with pressure medium, which is controlled depending on the highest load pressure of the consumer in each associated circle.

For the case that, for example, next to the two chains still at least a consumer of the equipment is operated should, it is possible to avoid a pressure medium shortage to interconnect both hydraulic circuits. This interconnection via a connection valve, via the the pressure lines connected to the two pumps and the load pressure signaling lines the two circles are interconnected. The activation of the Interconnection valve is dependent on the pressure medium supply to the additional consumer. In addition, can The operator manually intervene and the two circles manually interconnect.

The disadvantage of this solution is that, for example, when driving a connected to a hydraulic circuit consumer with high pressure medium demand and low pressure and driving a connected to the other circuit consumer with low pressure requirement and high pressure both circuits are connected via the interconnection valve, so that the higher load pressure of the latter circle also rests in the former circle. Due to this higher load pressure, the pump of the first circuit is raised, so that both circuits are raised to the higher pressure level. The pressure in the first-mentioned hydraulic circuit must then be appropriately throttled back to the pressure level required there, resulting in significant energy losses. Another disadvantage of in the US 6,170,261 B1 described solution is that a considerable effort to control the Zusammenschaltventils is required.

In the DE 102 545 738 A1 the applicant is shown an improved two-circuit system in which a Verschschaltventilanordnung is carried out with two pressure compensators, each of which is assigned to one of the circuits and via the function of the load pressure and the pump pressure in the associated circuit connection to the other circuit can be opened. A disadvantage of this solution is that the Verschschaltventilanordnung has a relatively complex structure.

In the DE 41 00 988 C2 discloses a dual-circuit hydraulic system in which the summation is switchable in response to the control of certain consumers. To eliminate the disadvantages described in the introduction, the interconnection of the two circuits to a single-circuit system is limited to cases in which this makes sense energetically.

at This known solution is done via interconnection a Verschschaltventilanordnung, in a basic position the connects both circles to a single circle system. The junction valve arrangement has a connect valve, which has a pilot-control valve arrangement from the above-described basic position in a locked position leaves to deactivate the summation. This adjustment via a pilot valve arrangement, which depends on The load pressures of the consumers of the two circuits can be controlled is.

adversely in this solution is that the Verschschaltventilanordnung always summed up in the basic position and only under certain operating conditions the summation is deactivated. Order now with this deactivation the explained in the beginning unfavorable operating conditions for the summation, on the other hand however, the summation in a wide range of driving the Enabling consumers is a significant technical device Effort required to the pilot control valve assembly and its Activation to realize.

In contrast, the invention has the object, a hydraulic dual-circuit system and a method for driving consumers of a hydraulic Two-circuit system to create, by the low device complexity ensures an optimized in terms of energy consumption summation.

These Task is by a hydraulic dual-circuit system with the features of claim 1 and a method with the features of the sibling Claim 19 solved.

In the inventive hydraulic Two-circuit system, the respective consumers assigned to a circle are supplied via a variable displacement pump with pressure medium. The two hydraulic circuits can be connected to each other arrangement by means of a switching valve, so that the variable displacement of one circle summed pressure medium in the other circle. According to the invention, a deactivation device is provided by means of which the pressure medium requirement can be detected in both circuits, and via which the interconnection valve arrangement can be deactivated if the pressure medium requirement in a circuit is smaller than the maximum pump delivery flow and greater than a switchover pressure medium requirement.

The inventive method works accordingly, wherein in one process step, the pressure medium requirement in both Circles recorded and the pressure medium requirement in the circles each with a maximum pump flow of this circle associated pump and with one below the maximum pump delivery rate lying switching pressure medium requirement of or this circle associated Consumer (s) is compared. In the case where the pressure medium requirement in the circuit to be switched smaller than the maximum pump flow rate and greater than the switching pressure medium requirement, the Verschschaltventilanordnung is deactivated, and thus the Summation stopped.

In this way, the above-described, energetically unfavorable operating conditions can be reliably avoided, the summation is switched according to the criteria usually provided, while the deactivation of this summation is independent of these criteria depending on the individual pressure medium requirement in each circle. Ie. unlike the solution according to the DE 41 00 988 C2 activating and deactivating the summation is largely independent of each other, wherein the deactivation device can deactivate the summation independently of the control pressures acting upon the interconnector valve arrangement.

Such a control strategy and such a dual-circuit system can generally be used in LS systems, in LUDV systems and also in EFM (Electronic Flow Management) systems. The basic structure of LUDV systems is, for example, in the post-published patent application DE 10 2006 053 897 described. The control of consumers according to the EFM principle is in the DE 103 54 022 A1 explains, the content of both patent applications is one of the disclosure of the present patent application, so that in the following only the essential elements for understanding the invention must be explained.

The Applicant also reserves the right to activate and / or Disable summation on EFM systems independently from the LUDV / LS systems described in more detail below in a separate patent application to pursue in the then also resorted to the disclosure of the aforementioned applications can be.

In a preferred embodiment of the invention, the interposing valve assembly has an interposing valve whose valve spool has two unidirectional control surfaces which are acted upon by the highest load pressure in the first circuit and by the pump pressure in the second circuit, respectively. The valve spool also has two in the other direction effective control surfaces, which are acted upon in accordance with the highest load pressure in the second circuit and the pump pressure in the first circuit. Such a ΔΔp valve is described in detail in US Pat DE 10 2006 053 897 explained.

about such a switching valve is in both circles only the load pressure corresponding to the actual requirements reported to each associated variable displacement, so that in the Case in which in one of the circles a high pressure with low pressure medium requirement is applied, the variable pump of this circuit is not started up and thus the energy losses compared to those described above Solutions are significantly minimized. This solution However, it does allow that in the case where one of the Circles a high pressure at high pressure medium requirement is applied, this high pressure is reported in the second circle, if in this one low load pressure is applied.

According to the invention this switching valve via the deactivation device regardless of the voltage applied to the switching valve Control pressures in its zero position or in a predetermined Position are adjusted to cancel the summation.

at A variant of the invention has this deactivation device a deactivation valve via which disables the Summation one of the two effective in one direction, with the pump pressure in the first or the load pressure in the second acted upon Control surface of the valve spool of the connection valve with the load pressure or the pump pressure in the other circle can be acted upon, so that the resulting control pressure difference at the valve spool is equal to zero.

there It is preferred if the valve spool for deactivation in both directions with the pump pressures in the first and in the second circle is applied.

In this embodiment, the Deactivation valve to be a continuously variable directional control valve that has four pressure medium connections and three control connections, wherein in a basic position of the deactivation valve at two input terminals of the load pressure in the first and in the second circuit is applied and assigned output terminals, the respective control surfaces are subjected to the respective load pressure. When adjusting the valve spool from this basic position, the input ports are zuusteuerbar and two other input ports aufsteuerbar, via which in each case that control surface which is acted upon in the normal position with the load pressure of a circle, when adjusting the valve spool with the pump pressure of the other circuit is applied - on the valve spool effective control pressure difference is then zero, so that it is moved back to the basic position.

alternative the deactivation device can be equipped with a proportionally adjustable Be executed pilot valve, over the at least one of the control surfaces of the valve spool with a higher or a lower control pressure can be applied, so that this is adjustable in a predetermined direction to the summation controlled to pick up.

at In a preferred solution, the pilot valve is steady adjustable directional control valve, over the to deactivate both unidirectional control surfaces be connected to each other, so that then in each direction of the respective higher pump pressure of a circle acts or one of the control surfaces is relieved.

These Discharge is then preferably by a connection with a Tank, so then by appropriate control of this pilot valve the switching valve is adjustable in its middle position.

alternative The pilot valve can also be designed as a pressure reducing valve be that about one of the one-way effective ones Control surfaces acting pressure is changed to controlled to adjust the junction valve in its basic position. In this case, each adjustment can be assigned a pressure reducing valve become

The Control of the pilot valve or the deactivation valve is preferably carried out electrically. Of course it is However, a hydraulic or electro-hydraulic control possible.

At the Two-cycle system according to the invention are preferably the pumps press and / or the load pressures in the Circles detected via pressure sensors or the like.

Having regard to the pressures detected by the pressure sensors can be estimated as a function of the expected performance enhancement (Q Δ _p and or pressure increase in a circle) then determines whether a summation is useful or not.

The Direction of summation can be detected via a displacement sensor the valve spool position of the connection valve are detected.

to Determining the actual pressure medium volume flow or the hydraulic Performance, the pump speed and its swivel angle can be detected.

In Dependence on the signals of these or other sensors then can the deactivation valve, the pilot valve or the metering orifice can be controlled to the interconnecting valve to bring into its locked position.

D. H. Such a system allows the control of Consumers according to the LS / LUDV principle or the EFM principle, in the former case, the pump depending on highest load pressure of the consumer is controlled while according to the EFM principle, the pump and also the metering orifice depending on is adjusted by reference values, via an operator, for example be adjusted by means of a joystick.

at LS or LUDV systems is the metering orifice assigned to each consumer associated with an individual pressure balance. The control of the variable displacement pump takes place depending on the highest load pressure in each circle.

The control can be further improved if, in each circuit via a further LS line (LS chain) and corresponding shuttle valves of the respective highest load pressure of the respective circuit is attacked and in the control of the interconnection valve 40 is taken into account.

According to one According to the control concept according to the invention, the interconnection valve arrangement is deactivated, if the pressure medium requirement in both circles is smaller than the maximum Pump flow is at one pump.

The Totalization can be maintained when of higher pressure Circle is promoted in the lower pressure circle.

other advantageous developments of the invention are the subject of further Dependent claims.

In the following, preferred embodiments of the invention will be described schematically Drawings explained in more detail. Show it:

1 a circuit diagram of a LUDV dual-circuit system according to the invention with a deactivation valve for deactivating a Verschschaltventilanordnung;

2 a circuit diagram of an EFM dual-circuit system, the basic structure of which 1 corresponds;

3 an EFM dual-circuit system with simplified deactivation valve and

4 An EFM dual-circuit system with two simple deactivation valves.

In 1 is a circuit diagram of a LUDV dual circuit system shown, the basic structure of the above-mentioned DE 10 2006 053 897 is known, so that only the essential elements of the invention will be discussed here. Such a dual-circuit system has two hydraulic circuits 1 . 2 , which in the illustration according to 1 only simplified without return are shown. The two circles 1 . 2 can be by means of a Verschschaltventilanordnung 4 connect with each other so that pressure medium from one of the circles 1 . 2 in the other circle 2 . 1 can be promoted. The junction valve arrangement 4 is a deactivation device 6 with a deactivation valve 7 assigned over which the function of the Verschschaltventilanordnung 4 can be deactivated or overridden.

Such a dual-circuit system can be used for example in an excavator control, for example, via each of the circles 1 . 2 a traction drive for each chain of a excavator undercarriage can be supplied independently with pressure medium. In addition to this travel drive, further consumers of the excavator, such as a slewing gear, a stick, a bucket or a boom, are actuated via the two-circuit system, wherein in each case one valve axis of the two-circuit system can be assigned to one of these consumers.

As shown in 1 every circle has 1 . 2 a variable displacement pump 8th . 10 , about each of which at least one consumer 12 . 14 is supplied with pressure medium. It is at a pressure port of each pump 8th . 10 with variable flow a supply line 16 . 18 connected to the entrance of an adjustable metering orifice 20 . 22 leads. The cross section of the respective inlet orifice 20 . 22 can be adjusted by an operator, for example via an electric joystick or a hydraulic joystick, so that the pressure medium volume flow to the associated consumer 12 . 14 depending on the respective opening cross-section of the inlet orifice 20 . 22 is adjustable.

At the exit of the metering orifice 20 . 22 is each a supply line 24 . 26 connected to the respective consumer 12 . 14 leads. In this supply line 24 . 26 Each is a LUDV pressure compensator 28 . 30 arranged in the opening direction from the pressure downstream of the metering orifice 20 . 22 and in the closing direction is acted upon by the highest load pressure of all consumers of the respective circuit, each via an LS line 32 . 34 and a shuttle valve cascade, not shown, of the driven consumers of the respective circuit 1 . 2 is tapped. In the control position of each LUDV pressure compensator 28 . 30 corresponds to the pressure in the pressure medium flow path between the metering orifice 20 . 22 and the associated LUDV pressure compensator 28 . 30 the highest load pressure, which then via the associated LUDV pressure compensator 28 . 30 on the individual load pressure of the consumer 12 . 14 is throttled. About these LUDV pressure compensators 28 . 30 is the pressure drop across the metering orifice 20 . 22 independent of load pressure, whereby in the case of a supersaturation, the pressure medium volume flow to all controlled consumers of a circuit 1 . 2 is reduced proportionally.

The activation of the respective variable displacement pump 8th . 10 takes place as a function of this highest load pressure in the load reporting lines 32 . 34 that via a pump control line 36 . 38 from the associated load reporting channel 32 . 34 is tapped.

About the interconnection valve assembly 4 can the two supply lines 16 . 18 be connected to each other, so that pressure medium can be promoted from one circle to the other circle (summing).

The junction valve arrangement 4 has at the in 1 illustrated embodiment, a connection valve 40 , which is mentioned in detail in the beginning DE 10 2006 053 897 is described. This connection valve 40 has two pressure ports P1, P2 and four control ports, which in the illustration according to 1 with LS2, LS2 '(circle 2 ) and LS1, LS1 '(circle 1 ) are designated. In the illustrated basic position, these connections are blocked. The two pressure ports P1, P2 are each via a pressure line 42 . 46 with the associated supply line 16 . 18 connected. The connection valve 40 is designed as a continuously adjustable valve and can be adjusted from the illustrated basic position (0) in the direction (a), in the pressure medium from the circle 2 in the circle 1 is promoted, in which case the two control terminals LS1, LS2 'are interconnected. In an adjustment in the direction (b) is correspondingly pressure medium from the circle 1 in the circle 2 summed up while the both control terminals LS2, LS1 'connected to each other. This connection valve 4 is designed as a so-called ΔΔp valve, with two control surfaces 46 . 48 when pressurizing the valve spool of the switching valve 40 in the direction of (a) apply while two more control surfaces 50 . 52 in the opposite direction (b) act on this valve spool.

The control area 46 is doing via a pressure control line 54 with the pressure in the pressure line 44 ie the pump pressure of the circle 2 applied. The other, in the direction of (a) effective control surface 48 is via an LS control line 56 with the highest load pressure of the circle 1 ie the pressure in the load-sensing line 32 applied. Correspondingly, at the direction of (b) effective control surface 52 the pump pressure in the supply line 16 on, via the pressure line 42 and another pressure control line 58 is tapped. The further control surface 50 is then correspondingly via an LS control line 60 with the highest load pressure of the circle 2 connected by the load reporting line 34 is tapped.

Up to here corresponds to the illustrated embodiment fully in terms of content in the DE 10 2006 053 897 described solution, so that reference can be made to the relevant statements with regard to the function and further details. The summation from one circle to the other then takes place as a function of the two pressure differences that occur on the control surfaces 46 . 50 and 48 . 52 Act.

According to 1 is the control port LS1 'via a LS branch channel 62 with the LS control line 56 connected. In a corresponding manner, the control channel LS2 'via an LS branch channel 64 with the LS control line 60 connected. The two other control connections LS2, LS1 'are each via an LS channel 68 . 70 with the LS control line 56 respectively. 60 connected, wherein in each LS channel 66 . 68 one each a pressure fluid flow to the associated control port LS1, LS2 enabling check valve 70 respectively. 72 is arranged. About the two check valves 70 . 72 it is ensured that a higher load pressure of the connected circuit can not be reported to the other circuit.

The two LS control lines 56 . 60 are at the in 1 illustrated embodiment via control lines 74 . 76 with two output ports A, B of the deactivation valve 6 connected. This is designed as a continuously adjustable directional control valve with seven connections and can be adjusted in (b), wherein the valve spool via a spring 78 biased towards its basic position (a).

The deactivation valve 6 besides the two connections A, B has a tank connection T and four input connections C, E, D, F; in the illustration according to 1 external connections C, F are in this case to the load reporting line 32 respectively. 34 connected. The two in 1 inside control terminals E, D are via pressure control channels 80 . 82 to the assigned pressure line 42 . 44 connected. In the spring-biased home position (a), the terminals B, C and A, D are connected together so that in the control lines 74 . 76 in each case the highest load pressure of the respective circle 1 . 2 is applied. The connections T, E and F are blocked.

In the illustrated embodiment, the deactivation valve 6 electrically via a proportional magnet 84 adjustable, which is controlled by a control unit, not shown. By energizing the proportional magnet 84 may be the valve spool of the deactivation valve 6 in the direction (b) are adjusted so that the pressure medium connection between the terminals B, C and A, D is controlled and the pressure medium connection between the terminals E, B and F, A is controlled, so that in the control lines 74 . 76 then according to the higher pump pressure of the respective circle 1 . 2 takes effect. In other words, with an adjustment in the direction (b), the previously with the highest load pressure in the circle 2 beauf hit control area 50 with the pump pressure of the circle 2 and the previously with the highest load pressure of the circle 1 applied control surface 48 with the pump pressure in a circle 1 applied. However, these pump pressures also act in the opposite direction on the other two control surfaces 46 respectively. 50 , so that the resulting control pressure difference by adjusting the deactivation valve 6 can be reduced to zero and the interconnecting valve 40 due to its preload in the home position (0) zurückverstellt and accordingly the summation is disabled or interrupted.

In principle, there are a large number of options, depending on a control signal, the effective control pressure difference at the interconnecting valve 40 to break the summation - the in 1 illustrated deactivation valve 6 is just one of those possibilities. When the power is switched off or the control signal at the proportional solenoid is reduced 84 becomes the deactivation valve 6 adjusted again in the direction of its illustrated basic position (a), so that the summation is reactivated and corresponding to the on the control surfaces 46 . 50 and 48 . 52 applied control pressure differences a summation takes place or both circles 1 . 2 can be operated as separate circuits.

The pump pressure in the supply lines 16 . 18 can each via pressure transducer 86 . 88 detected and via signal lines 90 . 92 reported to a control unit, not shown, in which these pressure signals are processed in the manner described below to the deactivation valve 6 head for. Accordingly, the maximum load pressure in the circuits can be detected by pressure transducers, not shown.

The circuit according to 1 can additionally with speed sensors 94 . 96 be carried out to detect the pump speed, the speed signals then according to signal lines 98 . 100 reported to the control unit.

Depending on the over the pressure sensors 86 . 88 determined pump pressure, via the speed sensors 94 . 96 recorded speed of the pumps 8th . 10 as well as their swivel angle and on the stored in the control unit pump characteristics then the actual flow rate of the two variable displacement pumps 1 . 2 determined and compared with the desired flow rate or with the maximum flow rate, so that depending on the respective actual flow rate, the summation is maintained or deactivated.

The direction in which is summed can be via a transducer 102 be detected, via which the position of the valve spool of the interconnection valve 40 is detected. The position signal of the position transducer 102 is also via a signal line 104 forwarded to the control unit and processed there.

At the in 1 shown LUDV system is the requested by the consumer pressure fluid quantity, ie the pressure medium requirement in each circle 1 . 2 when using a hydraulic joystick, for example, via the summed control pressure pst determined in the measuring diaphragm control lines 106 . 108 for adjusting the metering orifices 20 . 22 all consumers. These control pressures can be determined via pressure transducers. Accordingly, the pressure medium requirement is determined from the summed control signals in an electric joystick

According to a control concept according to the invention, the summation is deactivated by one circuit in the other, as long as the pressure medium requirement in each circle 1 . 2 below the maximum delivery volume flow of the respective variable displacement pump 8th . 10 is because this can then cover the pressure medium requirement of each circle.

If the pressure medium requirement in a circle above the maximum delivery volume of the associated variable 8th . 10 increases, deactivation is via the deactivation valve 6 switched off, so that a summation is possible. This summation takes place when, for example, the pressure medium requirement in a circle 1 greater than the maximum flow rate of the variable displacement pump 8th is, so then over the interconnecting valve 40 a summation from the circle 2 in the circle 1 is possible.

However, this summation is deactivated if the pressure medium requirement in the switched-on circuit 2 Although smaller than the maximum flow rate of the variable displacement pump 10 however, greater than a predetermined switching pressure medium demand in this circuit 2 is. This switching pressure medium requirement can be, for example, 80% of the maximum delivery volume flow. A summation at such a high utilization of the variable 10 would be disadvantageous in terms of energy, so that according to the inventive concept in fulfilling this condition (pressure medium requirement less than maximum flow rate, but greater than the switching pressure medium requirement (for example, 80% of the maximum flow rate)) from the control unit, a control signal to the proportional magnet 84 is discharged, so that the deactivation valve 6 is moved in the direction of its position (b) and thus the interconnection valve 40 is reset to its home position (0) regardless of the load pressures and pump pressure, and accordingly the summation is disabled.

When the connection valve 40 a displacement sensor 102 (please refer 1 ), it can be seen on the basis of the position of the directional valve spool, in which direction is summed and what pressure difference due to the pressure compensator function of the interconnecting valve 40 is being regulated. Thus, it is possible with the position of the switching valve 40 and determine from the pressure medium requirement and the detected load pressures whether summing makes sense from an energetic point of view or whether the summation should be deactivated.

As an additional decision criterion can still the load pressures of each circle 1 . 2 be detected, for example, via load pressure sensors, not shown, and in the case in which a summation of the load pressure higher in the lastlastnegigeren circle 1 . 2 takes place, no deactivation of the corresponding interconnecting valve 40 is set.

In the embodiment described above, the control of the two variable displacement pumps takes place 8th . 10 depending on the highest load pressure of the consumers of the respective circle 1 . 2 , where the metering orifice 20 . 22 for example, via a joystick are adjustable to the pressure medium flow to the consumers 1 . 2 adjust. The Circuit according to 1 can also be used in classic LS systems in which, for example, the pressure compensator is connected upstream of the metering orifice and is acted upon in the opening direction by the individual load pressure and in the closing direction by the pressure upstream of the metering orifice.

2 shows a circuit with the basic structure according to 1 , this system is operated according to the EFM principle. The basic structure of the circuit according to 2 corresponds largely to that of the circuit according to 1 , so that reference is made to these statements with regard to the basic structure.

At the in 2 shown EFM solution is the control of the variable displacement pump 8th . 10 not as a function of the highest load pressure of the load, but as a function of the setpoint set via a joystick. With an electric joystick, the determination of the total pressure medium requirement is made by summing the individual control signals (on the signal lines 106 . 108 ). In the case of a hydraulic joystick, the pressure medium requirement is determined by summing the control pressures (pst) which are set via the joystick and which may also be detected by pressure sensors (not shown).

From these control pressures pst and the control signals can then be the pressure medium requirement (setpoint) in each circle 1 . 2 be determined, so that according to the criteria described above, the summation is disabled as long as the pressure medium required is in a circle below the maximum delivery volume of this circle. The summation is activated as soon as the pressure medium requirement in the one circle above the maximum flow rate of the associated pump 8th . 10 lies. This summation from one circuit to the other circuit is turned off when the pressure medium demand in the one circuit is greater than the switching pressure medium demand, which - as stated above - can be about 80% of the maximum flow rate of the associated pump.

The above-described decision whether a summation makes sense or can not also be dependent on the actual LS pressure level of each circle are taken. This pressure level can, as described above, detected via the pressure sensors become. Alternatively, it is possible for every consumer to assign an own LS message chain to pick up the load pressure, so that the actual LS pressure level of each circuit is determined can.

If, as stated above - via their own pressure sensors, the actual maximum load pressure in the respective circuits 1 . 2 can be detected, and from the EFM control, the actual volume flows, which can be determined for example from the pump speed, the swivel angle, the pump pressure and the characteristics of the pump, a performance-related assessment of the situation can be performed, and in response Performance assessment, whether the summation in terms of energy sense or not makes sense.

As already explained in the LUDV system, by determining the valve spool position of the interconnecting valve 40 be recognized, in which direction is summed and what pressure difference at the interconnecting valve 40 is controlled so that these parameters can also enter into the decision whether the summation remains active or is deactivated.

In the case where the pump 8th . 10 each carried out with a speed sensor, in addition, the currently available torque and the actual amount of pump can be taken into account in the decision.

If the diesel control of the excavator still that available standing diesel torque or the current pressure of the engine as a signal, it is beneficial to do so in the control strategy to take into account.

As already mentioned, the pressure sensors are 86 . 88 not necessarily, however, the consideration of these signals improves the accuracy with which the predetermined control strategies are realized.

In the above-described solution according to 2 Thus, depending on the explained criteria, the deactivation valve 6 controlled via the control unit, not shown, to keep the summation active or disable.

In principle, EFM solutions can be applied to the deactivation valve 6 according to 2 be waived, since the control pressure difference at the interconnecting valve 40 also by controlling the measuring aperture 20 . 22 can be varied. In an EFM system according to 2 controls the control unit, not shown, both the pump quantity and the opening cross section of the metering orifice 20 . 22 , which is adjusted depending on the pressure medium requirement. The amount of pump and the opening cross-section are usually in a defined ratio. If, for example, a pressure medium requirement of 80 l / min is requested via the joystick, then the pump will accordingly be set to a delivery flow of 80 l / min. In addition, the metering aperture 20 . 22 placed in a position where above the metering orifice a vorbe a certain pressure loss of, for example, 10 bar is generated. With this ratio is then the Δp at the associated control surfaces, for example 56, 50 of the interconnecting valve 40 Are defined. As long as the other circle is dealt with accordingly, the other two control surfaces will also be used 48 . 52 acted upon by a corresponding Δp, so that the valve spool of the interconnecting valve 40 remains in its illustrated basic position (0). By means of the control unit, this Δp can now be consciously changed in an EFM system by passing the metering orifice 20 . 22 or the delivery volume flow of the associated variable displacement pump 8th . 10 Adjusted a circle and thus deliberately adjusted the Δp on one side, so that the switching valve 40 is adjusted in dependence on this newly set Δp and thus the summation is activated or deactivated.

This pure EFM control without deactivation valve 6 Again, according to the criteria described above, depending on the pressure medium requirement, the hydraulic power, the set target value, etc. take place. This concept can also be followed up in a separate application.

In 3 is an EFM principle that is opposite to the solution in 2 is somewhat simplified, but in the basic structure is identical. A difference between those in the 2 and 3 illustrated systems is that in the embodiment according to 3 the LUDV pressure compensators 28 . 30 are designed as 3-way pressure compensators, which are locked in their basic position and when controlling a consumer - just like the LUDV pressure compensators in 2 - be adjusted to a control position, in which the downstream of the orifices 20 . 22 applied maximum load pressure of each circuit to the individual load pressure of the associated consumer 12 . 14 is throttled. In the case where the assigned consumer 12 . 14 the maximum load pressure of the respective circle 1 . 2 is the LUDV pressure compensator 28 . 30 to the left ( 3 ) adjusted to its end position, in which this maximum load pressure in the load-sensing line 32 . 34 is reported. Also in the variant according to 3 is the above-described switch valve 40 provided in the representation according to 3 in its summation position (b) is adjusted by pressure medium from the circle 1 in the circle 2 is summed up.

The control surfaces 46 . 48 . 50 . 52 are with the same pressure differences as in the embodiment according to the 1 and 2 so that further explanations are unnecessary in this regard.

Another difference is that in the LS control line 60 over which the control surface 50 with the in the load reporting line 34 adjacent highest load pressure of the circle 2 is acted upon, a throttle check valve 110 is provided, which is a control oil flow in the direction of the control surface 50 limited control space permits, while the return flow takes place via the throttle section.

Deactivation of the switching valve 40 via a deactivation device 6 in the illustrated embodiment, with a continuously adjustable 3/3-way pilot valve 112 is executed. This has three ports A, B and T, the latter tank port T is connected to a tank. The two ports A, B are via channels 114 . 116 connected to the control rooms, through the control surfaces 50 respectively. 52 are limited.

A valve spool of the pilot valve 112 is via a spring arrangement 118 biased to a middle position (0) in which the terminals A, B, T are shut off. The steady adjustment of the valve spool via a magnet assembly 120 , wherein the valve spool in the direction of a position (a) is adjustable, in which the two connections A, B and thus the control channels 114 . 116 connected to each other. In an adjustment of the valve spool in the direction (b), the port A is connected to the tank port T, so that the control channel 114 is relieved to the tank while the port B remains shut off. Consequently, when adjusting the pilot valve 112 in direction (a) in direction (b) on the control surfaces 50 . 52 acting Druckkraftrultultierende increases, while in an adjustment in the direction (b) this pressure force resulting is reduced. Accordingly, by adjusting the pilot valve 112 in the unloading position (b) or the pressure build-up position (a) of the directional valve spool of the interconnecting valve 40 controlled to be adjusted in the direction of its center position to the summation (see 3 ). The control is again based on the same criteria and control strategies as in the previously described embodiments, so that will not be discussed here. It is about the displacement sensor 102 monitors whether the directional valve spool has reached its center position.

4 Finally, shows an embodiment in which instead of the single pilot valve 112 two continuously adjustable pressure reducing valves 122 . 124 are provided, via which the on the valve spool of the interconnecting valve 40 effective control pressure difference is set. In the illustrated embodiment can on these pressure reducing valves 122 . 124 the control surfaces 50 . 48 be acted upon control pressure. According to the previous explanations acts on these control surfaces 48 . 50 normal way, ie with acti fourth connection valve 40 the highest load pressure of the circles 1 . 2 , each via the load reporting line 32 . 34 is tapped. The output of each pressure reducing valve 122 . 124 is via a control channel 114 respectively. 126 with the from the control surface 48 or from the control surface 50 limited control space of the connection valve 40 connected. The input connection of the 3-way pressure reducing valves 122 . 124 is in each case to a control pressure line 128 connected, in which a comparatively high control pressure is applied, by controlling the electrically adjustable pressure reducing valves 122 . 124 can be reduced to a predetermined control pressure, which then in the control channel 114 respectively. 126 is applied. The control of the two pressure reducing valves 122 . 124 occurs via the control unit in dependence on the above-described control strategies.

By suitable adjustment of these pressure reducing valves 122 . 124 can be the valve spool of the connection valve 40 to its home position (0) to deactivate a summation. As in 4 indicated, it may be advantageous in a deactivation of the summation, the LS control lines 56 . 60 via only indicated valve elements for load signaling line 34 . 32 shut off and the from the control surfaces 46 . 52 limited control rooms to the tank T to relieve pressure and the lines 58 respectively. 54 to the pressure line 42 respectively. 44 shut off so that essentially alone over the pressure reducing valves 122 . 124 set pressure difference on the valve spool of the connection valve 40 acts. In principle, it is also possible to adjust the Verschaltungsventils alone on the pressure reducing valves 122 . 124 to control, so that on the complex ducting to pressurize the control surfaces 46 . 48 . 50 . 52 can be dispensed with load pressure and pump pressure.

In all described embodiments, the pressure signals of the pressure sensors 86 . 88 for controlling the directional valve spool position of the interconnection valve 40 be used. Also in the embodiment according to 4 it is beneficial to the displacement sensor 102 to provide the valve spool position.

In the above-described embodiments, a one-piece connection valve 40 described. Of course, the inventive concept can also be applied to systems in which each circle 1 . 2 a separate interconnecting valve is assigned. Such a solution is for example in the aforementioned DE 102 55 738 A1 the applicant explains.

In principle, the pilot valves described on the basis of an EFM solution can be used 112 and the pressure reducing valves 122 . 124 also for LUDV or LS systems to deactivate the summing function.

Disclosed are a hydraulic dual-circuit system for controlling consumers and a method for driving consumers of a hydraulic Two-circuit system, wherein the two circuits via an interconnecting valve arrangement with each other are connectable, so that the variable displacement of a circuit pressure medium summed up in the other circle. The dual-circuit system has a deactivation device, via the summation is deactivated when the pressure medium requirement in the connected circuit smaller than the maximum pump flow and greater than a switching pressure medium requirement is. This can, for example, at about 80% of the maximum pump flow lie.

1

circle

2

circle

4

Interconnecting valve arrangement

6

Deaktierungseinrichtung

7

deactivation valve

8th

variable

10

variable

12

consumer

14

consumer

16

supply line

18

supply line

20

metering orifice

22

metering orifice

24

supply line

26

supply line

28

LUDV pressure

30

LUDV pressure

32

Load-sensing line

34

Load-sensing line

36

Pump control line

38

Pump control line

40

Interconnecting valve

42

pressure line

44

pressure line

46

control surface

48

control surface

50

control surface

52

control surface

54

Pressure control line

56

LS control line

58

Pressure control line

60

LS control line

62

LS branch channel

64

LS branch channel

66

LS-channel

68

LS-channel

70

check valve

72

check valve

74

control line

76

control line

78

feather

80

Pressure control line

82

Pressure control line

84

proportional solenoid

86

pressure sensor

88

pressure sensor

90

signal line

92

signal line

94

Speed sensor

96

Speed sensor

98

signal line

100

signal line

102

transducer

104

signal line

106

Orifice control line

108

Orifice control line

110

Speed Controller

112

pilot valve

114

control channel

116

control channel

118

spring assembly

120

magnet assembly

122

Pressure reducing valve

124

Pressure reducing valve

126

control channel

128

Control pressure line

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 6170261 B1 [0002, 0004]
• - DE 102545738 A1 [0005]
• - DE 4100988 C2 [0006, 0013]
• - DE 102006053897 [0014, 0016, 0043, 0049, 0051]
• - DE 10354022 A1 [0014]
• - DE 10255738 A1 [0088]

Claims (22)

Hydraulic dual-circuit system for controlling consumers ( 12 . 14 ), each hydraulic circuit ( 1 . 2 ) a variable displacement pump ( 8th . 10 ), over which this circle ( 1 . 2 ) associated consumers ( 12 . 14 ) are supplied with pressure medium, wherein the two circles ( 1 . 2 ) by means of a connection valve arrangement ( 4 ) are connectable to each other in such a way that the variable displacement pump ( 8th . 10 ) of a circle ( 1 . 2 ) Pressure medium in the other circle ( 2 . 1 ), characterized by a deactivation device ( 6 ), on which the pressure medium requirement in both circles ( 1 . 2 ) is detectable and via which the Verschschaltventilanordnung ( 4 ) can be deactivated if the pressure medium requirement in a circle ( 1 . 2 ) is less than the maximum pump flow rate and greater than a switching pressure medium requirement. Dual circuit system according to claim 1, wherein the interconnecting valve arrangement ( 4 ) a connection valve ( 40 ) whose valve spool ( 2 ) unidirectional control surfaces ( 46 . 48 ) of the highest load pressure in the first circle ( 1 . 2 ) or from the pump pressure in the second circuit ( 2 . 1 ) and two in the other direction effective control surfaces ( 50 . 52 ), which has the highest load pressure in the second circle ( 2 . 1 ) or the pump pressure in the first circle ( 1 . 2 ) can be acted upon. Dual circuit system according to claim 2, wherein the interconnecting valve ( 40 ) via the deactivation device ( 6 ) is adjustable independently of the applied according to claim 2 control pressures in its zero position. Dual circuit system according to claim 3, wherein the deactivation device ( 6 ) a deactivation valve ( 7 ), via which for deactivating in each case one of the two effective in one direction, with the pump pressure in the first and the load pressure in the second circle ( 1 . 2 ) ( 46 . 48 ; 50 . 52 ) with the load pressure or the pump pressure in the other circle ( 2 . 1 ) are acted upon, so that the resulting control pressure difference is zero. Two-circuit system according to claim 4, wherein a valve spool of the interconnecting valve ( 40 ) for deactivating in both directions with the pump pressures in the first and second circuits ( 1 . 2 ) is acted upon. Dual circuit system according to claim 4 or 5, wherein the deactivation valve ( 7 ) is a continuously adjustable control valve, wherein in a basic position at two input terminals of the load pressure in the first and in the second circle ( 1 . 2 ) and via associated output terminals (A, B) the corresponding control surfaces ( 48 . 50 ) are acted upon by the respective load pressure, wherein when adjusting from a basic position (a) these input terminals (C, D) steerable and two other input terminals (E, F) are aufsteuerbar, on the respective control surface ( 48 . 50 ) in the normal position with the load pressure of a circle ( 1 . 2 ) is applied when adjusting the valve spool with the pump pressure of the other circuit ( 2 . 1 ) is acted upon. Dual circuit system according to claim 4, wherein the deactivation device ( 4 ) a proportionally adjustable pilot valve ( 112 ), via the at least one of the control surfaces ( 50 . 52 ) can be acted upon with a control pressure, so that the valve spool of the interconnection valve ( 40 ) is adjustable in a predetermined direction. Dual-circuit system according to claim 7, wherein the pilot valve ( 112 ) is a continuously variable directional control valve, via the two effective in one direction control surfaces ( 50 . 52 ) can be acted upon by the same control pressure or one of these control surfaces ( 50 ) is relieved. Two-circuit system according to claim 8, wherein this Relief pressure is the tank pressure. Dual-circuit system according to claim 7, wherein the pilot valve at least one pressure reducing valve ( 122 . 124 ). Dual circuit system according to one of the preceding claims, wherein the deactivation device ( 6 ) is electrically operated. Dual-circuit system according to one of the preceding claims, with pressure sensors ( 86 . 88 ) for detecting the pump pressure and / or the maximum load pressure of each circuit ( 1 . 2 ). Dual-circuit system according to one of the preceding claims, with a displacement sensor ( 102 ) for detecting a slide position of the connection valve ( 40 ). Dual-circuit system according to one of the preceding claims, with rotational speed sensors ( 94 . 96 ) for detecting the pump speed and with swivel angle sensors for detecting the swivel angle of the pumps ( 8th . 10 ). Dual-circuit system according to one of the preceding claims, having a control unit, for controlling in each case one of a consumer ( 12 . 14 ) of a circle ( 1 . 2 ) associated metering orifice ( 20 . 22 ) and arranged in this circle variable pump ( 8th . 10 ) in response to a control signal (EFM) set by an operator. Dual circuit system according to one of the claims 12 to 15, having a control unit for activating the deactivation device ( 6 ) depending on the pressure medium requirement of the driven consumers to the interconnecting valve ( 40 ) in its locked position. A dual circuit system according to any one of claims 1 to 16, wherein each circuit ( 1 . 2 ) is designed as an LS or LUDV system and to each consumer ( 12 . 14 ) a metering orifice ( 20 . 22 ) and an individual pressure scale ( 28 . 30 ) and the variable displacement pump ( 8th . 10 ) as a function of the highest load pressure in the respective circuit ( 1 . 2 ) is controllable. Dual circuit system according to one of the preceding patent claims, each circuit ( 1 . 2 ) an LS line for picking up the individual load pressure of each consumer 12 . 14 assigned. Method for driving consumers of a dual-circuit system, each hydraulic circuit ( 1 . 2 ) a variable displacement pump ( 8th . 10 ), over which in this circle ( 1 . 2 ) consumers ( 12 . 14 ) are supplied with pressure medium, wherein the two circles ( 1 . 2 ) by means of a cohesion valve arrangement ( 4 ) can be connected to one another in such a way that the variable displacement pump ( 8th . 10 ) of a circle ( 1 . 2 ) Pressure medium in the other circle ( 2 . 1 ), characterized by the steps: - Detecting the pressure medium requirement in both circles ( 1 . 2 ) - comparing the pressure medium requirement in the one circle ( 1 . 2 ) with a maximum pump flow rate of this circuit ( 1 . 2 ) associated pump ( 8th . 10 ) and with a switching pressure medium requirement of the circuit below the maximum pump delivery flow ( 1 . 2 ) associated consumer ( 12 . 14 ) and - deactivating the interconnection valve arrangement ( 4 ) if the pressure medium requirement is less than the maximum pump flow rate and greater than the switching pressure medium requirement. The method of claim 19, wherein the interconnect valve assembly ( 4 ) is deactivated when the pressure medium requirement in both circles ( 1 . 2 ) smaller than the maximum pump delivery flow in each case one variable displacement pump ( 8th . 10 ). The method according to claim 19 or 20, wherein the summation remains activated when from the higher pressure to the lower pressure ( 1 . 2 ). Method according to one of the claims 19-21, where the pump pressure and / or the maximum load pressure of each circuit is detected and depending on an expected Power increase is decided, whether a summation makes sense or not.