DE102014004932B3 - circuitry - Google Patents

Abstract

A circuit arrangement for controlling hydraulic consumers (10, 12, 14) which are connected in series and which are supplied for their operation by at least one load-sensing control pump (17) via a pressure supply port (P), each by means of an assignable valve means between a Standby operation and a working operation and vice versa is operable, which is arranged between the pressure supply port (P) and a supply line (A1) at least one hydraulic consumer (10) and having an actuatable valve (40), characterized in that the valve ( 40) can only be controlled hydraulically, that at least one actuation signal for the pending actuation originates from a load tap (34) at least at one of the hydraulic consumers (10) and that a metering orifice (46) between the valve (40) and at least one hydraulic consumer ( 10) is connected in the assignable supply line (A1).

Description

The invention relates to a circuit arrangement for controlling hydraulic consumers, which are connected in series and which are supplied for their operation by at least one load-sensing control pump via a pressure supply port, each operable by means of an assignable valve means between a standby mode and a working mode and vice versa is, which is arranged between the pressure supply port and a supply line of at least one hydraulic consumer and having an actuatable valve.

Mobile working machines, such as so-called Winterdienststreuer be built with a variety of carrier vehicles as a means of transport. Such work machines regularly have different controllable and operable hydraulic consumers, for example in the form of hydraulically driven constant motors. Thus, in the case of the mentioned winter service spreaders, for example, a consumer with his hydraulic motor can serve to drive a transport screw, for the purpose of transporting road salt; another consumer with a corresponding engine can then include a spreading plate for distributing the road salt on the road and another consumer with controllable motor to drive a feed pump to bring, for example, a liquid road salt mixture of winter maintenance spreader on the road.

The pertinent consumer enumeration is only an example and a variety of other consumers, even for other applications, in other types of machinery or work equipment would be conceivable. In order to be able to supply with the already mentioned Winterdienststreufahrzeugen with the smallest possible pump volume, the normally 2 to 4 hydraulically powered consumers accordingly, they are regularly connected in series, ie each consumer is the complete pump flow available. As a pump while a constant pump is used. A hydraulic circuit diagram showing the known solution is the subject of 1 the present protective law.

Since the mentioned carrier vehicles are increasingly equipped with so-called load-sensing pumps (LS pumps), there is a fundamental desire to be able to operate the series connection with such pumps. Due to the principle, the respective LS pump must be operated as a fixed displacement pump, since in the series connection the excess volume flow must flow to the tank via individual pressure compensators, with the result that the LS pump would then swing out to a maximum delivery volume.

In order to prevent this behavior, the LS pump is regularly operated as a fixed displacement pump with an upstream throttle valve. By closing the throttle valve, the LS pump can be switched to standby mode, with the upcoming load sensing pressure in the fluid flow direction behind the throttle valve ultimately representing the control fluid flow for the actuatable LS pump. The pump flow itself, however, is determined by the free cross section of the throttle valve.

A well-known series circuit with so-called LS-Vorschaltventil is exemplary in the 2 in the following description text.

Although the latter genus-forming solution is very advantageous and in particular allows safe operation of the LS supply pump, it represents a certain effort both from the control side and from the cost side ago to electrically control the additional ball valve to control the LS pump.

The WO 2005/075833 A1 describes a circuit arrangement for controlling hydraulic consumers which are connected in series one behind the other and which are supplied for their operation by at least one load sensing control pump via a pressure supply port which is operable by means of an assignable valve device between a standby mode and a working mode and vice versa, the is arranged between the pressure supply port and a supply line of at least one hydraulic consumer and having an actuatable valve.

Based on this prior art, the present invention seeks to ensure the known solutions, while maintaining their advantages, namely a meaningful, functionally reliable operation, to further improve that achieved by both the manufacturing effort and on the part of the control effort to be operated a reduction is.

This object is achieved by a circuit arrangement with the features of claim 1 in its entirety.

The fact that according to the characterizing part of patent claim 1, the valve is exclusively hydraulically controlled that at least one actuation signal for the pending actuation comes from a load tap at least on one of the hydraulic consumers, that the load tap is connected to the valve via a load sensing control line and that a metering orifice is connected between the valve and at least one hydraulic consumer in the assignable supply line, the circuit arrangement can be switched purely hydraulically between an active operation and a standby mode without the use of an electrical activation Operation automatically switch back and forth. The hydraulic control is without electrical components and is therefore very reliable in use. Also can be dispensed with a complicated, costly electronic control structure.

In order to switch the LS pump back and forth between active operation and standby mode, it is necessary to change the volumetric flow demand. For this purpose, according to a preferred embodiment of the invention, a metering orifice is switched on and off by a hydraulically actuated directional control valve. The switching signal to this comes preferably from a Lastdruckabgriff to the individual, connected to the circuit hydraulic consumers.

In order to allow the pressure to build up on the consumer, it is preferably provided that a low standby volume flow continues to flow. This is controlled by a second aperture which always remains open within the circuitry.

If all connected loads are inactive, the load sensing control line is depressurized and the directional control valve is closed. Thus, the pump only promotes the volume flow through the small aperture is requested. The pressure is determined by the load-sensing pressure difference of the pump.

If a consumer is now switched on by the operator of the working machine, the pressure in the LS control line rises due to the fact that the standby volume flow flows to the consumer. As a result of this increase in pressure, the directional valve switches over and releases the "large aperture". Thus, according to the "large aperture", the volumetric flow demand to the pump increases and this swings to provide the required operating volume flow for the series connection.

The functionality of the series connection remains completely unaffected. By replacing the directional control valve with a suitable plug, the system can also be operated on a fixed displacement pump.

Further advantageous embodiments of the solution according to the invention are the subject of the dependent claims.

In the following, the solution according to the invention is based on three hydraulic circuit diagrams according to the 1 to 3 explained in more detail, wherein the 1 and 2 Solutions in the prior art relate.

To the structure and operation of the solution according to the invention after the 3 First, the state of the art according to the content of the 1 and 2 explained in more detail.

The 1 shows a circuit arrangement for driving three hydraulic consumers 10 . 12 . 14 In the form of constant hydraulic motors, as shown in the 1 are connected in series and for their operation by means of a constant pump 16 via a pressure supply port P from a storage reservoir, such as a hydraulic tank 15 supplied with fluid prescribable pressure. In the 1 shown outer frame 18 relates to the actual area of the circuit arrangement, wherein the respective consumer 10 . 12 . 14 via supply lines A1, A2 and A3 and return lines B1, B2, B3 is connected to the still to be described circuit arrangement fluid or media leading.

The respective circuit arrangements shown in the figures are intended to be used in particular for winter service gritting vehicles, the first consumer 10 with its hydraulic motor to drive a screw conveyor, not shown, can serve for the purpose of transporting road salt. The second consumer 12 can include with its engine a scattering plate for distributing a road salt on the road and the last consumer 14 with its controllable constant-motor can serve to drive a feed pump to bring, for example, a liquid road salt mixture of winter maintenance spreader on the road. For the sake of simplicity, the graphic reproduction of transport screw, spreading plate and application pump was dispensed with. Furthermore, it goes without saying that the respective circuit arrangement according to 1 to 3 can also be used for other purposes as Winterdienststreuer use, but where the hydraulic consumers 10 . 12 . 14 are always arranged in the series connection shown to each other.

Between the respective inlet and return lines A1, B1; A2, B2 and A3, B3 of each hydraulic consumer 10 . 12 . 14 is a pressure balance 20 switched, with each pressure balance 20 as shown in the 1 on the input and output side to a common supply line 22 connected. The input C1 of the common supply line 22 opens into the supply line A1 and the output C2 of the supply line 22 terminates in the last return line B3 of the indicated series circuit. Furthermore, the return line B3 opens from the last consumer 14 coming into the tank connection T off. Between the pressure supply port P and the tank port T is an adjustable and electromagnetically actuated pressure relief valve 24 switched, for example, set to a pressure value of 200 bar to secure the respective hydraulic circuit in the case of over-supply, in particular in the form of an overpressure, from the pump side, the fluid path via a connecting line 26 between pressure supply connection P and tank connection T produces.

Via control lines 28 . 30 which are arranged on opposite sides respectively on the control piston of each pressure balance 20 act, is always the inlet-side pressure in the supply lines A1, A2, A3 of each hydraulic consumer 10 . 12 . 14 as well as by means of a throttle or aperture 32 throttled pressure in the form of a load tap 34 located in the respective supply line A1, A2 and A3 behind a 2/2-way proportional valve 36 is arranged. Furthermore, also the pressure compensators 20 constructed in the manner of a 2/2-way proportional directional valve concept.

To get along with the smallest possible pump flow rates, as in 1 represented, the individual hydraulic consumers 10 . 12 . 14 interconnected in series, allowing every consumer 10 . 12 or 14 the complete pump volume flow is available. To ensure a secure supply of individual consumers 10 . 12 . 14 Incidentally, due to the way valves 36 can be switched within the circuit and therefore go into active mode, the constant pump must 16 in a correspondingly high degree fluid with a predetermined pressure ready and should the total volume on the hydraulic consumers are not consumed, the excess proportion on the respective then addressed pressure balance 20 given to the tank connection side T. Such loss operation via the pressure compensators 20 Although it is reliable, but leads to energy losses, in particular from the operation of the pump 16 result.

To counteract the pertinent disadvantages, is in a circuit arrangement according to the illustration of the 2 has already been proposed, which also otherwise proves to be disadvantageous constant pumps for the pressure supply of the circuit arrangement by load sensing pump concepts 17 to be replaced, wherein also known in circuit arrangements, for example according to the 2 , the fundamental problem is that when not removed hydraulic fluid through the series-connected consumer 10 . 12 . 14 the excess medium via the individual pressure compensators 20 Depending on the application, it must be brought to the tank side T in an energy-dissipating manner. So a solution in which the constant pump 16 after 1 through a LS pump 17 is replaced, which would then also be operated as a constant pump, then makes no sense in this respect.

To address the pertinent disadvantage is in the solution after the 2 proposed, an electrically controllable throttle valve 40 provided in the first supply line A1 between the pressure supply port P and the input C1 of the supply line 22 for the individual pressure compensators 20 is switched. In the direction of the 2 is seen behind the throttle valve 40 in the manner of an electrically controllable 2/2-way proportional directional control valve on the output side, the control pressure in the supply line A1 tapped and via an LS control line 42 , which is connected to a LS connection of the valve arrangement, for controlling the delivery volume to the corresponding control device of the LS pump 17 forwarded. By targeted activation and closing of the directional control valve 40 can be connected to the pressure supply side P LS pump 17 be switched to the so-called standby mode, with the addressed LS tap on the LS control line 42 the pump flow through the released cross-section of the throttle valve 40 is determined.

Since the proposed circuit arrangement is particularly preferred for winter maintenance equipment, especially in the form of gritting vehicles, application and is often required in this technical area, that the control is very inexpensive, not all devices and machines mentioned above have the possibility of said ballast in the form of the throttle valve 40 for controlling the LS pump 17 to bring with. In particular already delivered Winterdienstgeräte can be with the in 2 The solution presented only very poorly retrofit, as often not readily available the connections for the electrical control of the throttle valve 40 ,

The in the 2 shown circuit has been explained only insofar as they differ significantly from the solution to the 1 differs, the previously used reference numerals and components of 1 in the 2 are provided with the same reference numerals and the extent already taken so far apply to the components according to the 2 , Furthermore, in turn for the 3 the same reference numerals are used for the same components, so that in this respect also the statements made so far for the circuit diagram representation according to the 3 apply, which is explained, moreover, only in so far as they are authoritative, that is, inventive of the above-known solutions according to the 1 and 2 different.

In the solution after the 3 is the corresponding valve 40 to the valve solution after the 2 designed as only hydraulically operated directional control valve, which in his in the 3 shown blocking position under the action of an energy storage in the form of a compression spring 41 comes, provided no hydraulic control on the opposite control side of the valve 40 is present. For the pertinent hydraulic control has the directional control valve 40 on his the compression spring 41 opposite, opposite control side an input for the LS control line 42 on, their input pressure via another LS control line 44 that gets from the load tap 34 of every hydraulic consumer 10 . 12 . 14 coming to the LS control line 42 with the check valve open 43 is switched on. The directional valve 40 is formed in the manner of a 2/2-way switching valve and with a corresponding hydraulic actuation via the LS control lines 42 and 44 becomes the valve 40 switched into its fluid-conducting passage position.

There is also a metering orifice 46 between the valve 40 and the input point C1 of the supply line 22 connected in the first supply line A1, which preferably has a correspondingly large opening cross-section. Instead of the metering orifice 46 can also occur a suitably designed throttle. Furthermore, behind the measuring aperture 46 and in front of the entrance of the valve 40 pointing in the direction of the pressure supply connection P a parallel branch 48 switched with another second aperture 50 , which allows the flow of a low standby volume flow, which will be explained in more detail below. Furthermore, like that 3 shows, the other LS control line 44 by means of a third aperture 52 or throttle in a relieving manner connected to the tank side T of the circuit arrangement, including the corresponding connection line of the third panel 52 opens into the return line B3.

To the LS pump 17 Now you can switch back and forth between operation and standby, the volumetric flow demand is changed. This is the metering or orifice plate 46 behind the directional valve 40 switched and the flow of the aperture 46 can through the hydraulically actuated directional control valve 40 controlled, in particular switched on and off. The actual switching signal for the hydraulic control of the directional control valve 40 comes from the respective load pressure tap 34 in the supply lines A1, A2 and A3 to the individual hydraulic consumers 10 . 12 . 14 , To the pressure build-up at the respective consumer 10 . 12 . 14 To allow safe, a low standby volume flow is allowed, which is beyond the second aperture 50 , which always remains open with a predeterminable cross-section, is controlled.

Are all consumers 10 . 12 . 14 inactive, is the LS line 42 . 44 depressurized and the hydraulically controllable directional control valve 40 is closed. Thus, the LS pump promotes 17 only the volume flow through the small aperture 50 is requested. The pressure is due to the necessary load sensing differential pressure of the pump 17 certainly.

Will now be at least one of the consumers 10 . 12 or 14 switched on in this order, the pressure in the LS control line increases 42 . 44 This is because the standby volume flow now flows to the respectively assigned consumer. Due to this increase in pressure, the directional valve switches 40 around and gives the big aperture 46 free. This increases according to the large opening cross-section of the aperture 46 the volumetric flow demand to the pump 17 , Which then pivots so far controlled by the pressure in the load-sensing connection LS to the required operating volume flow for the consumer 10 . 12 . 14 to provide. The functionality of the indicated series connection remains completely unaffected by the pertinent measure.

By replacement of the directional valve 40 by a corresponding end plug (not shown) in the hydraulic circuit, the system can then turn on a constant pump 16 , as already shown, are operated. While with the solutions after the 1 and 2 to the prior art, the pressure relief valve 24 was electrically controlled, was in the solution after the 3 in turn selected an exclusively hydraulic solution that gets along with the hydraulic control pulse in the connecting line between the pressure supply port P and tank port T.

Claims (10)

Circuit arrangement for controlling hydraulic consumers ( 10 . 12 . 14 ) which are connected in series one behind the other and for their operation by at least one load-sensing control pump ( 17 ) are supplied via a pressure supply connection (P), which in each case can be operated by means of an assignable valve device between a standby mode and a working mode and vice versa, between the pressure supply connection (P) and a supply line (A1) of at least one hydraulic consumer ( 10 ) is arranged and an actuatable valve ( 40 ), characterized characterized in that the valve ( 40 ) is exclusively hydraulically controllable that at least one actuation signal for the pending actuation of a load tap ( 34 ) at least at one of the hydraulic consumers ( 10 ), that the load tap ( 34 ) via a load-sensing control line ( 44 ) with the valve ( 40 ) and that a metering orifice ( 46 ) between the valve ( 40 ) and at least one hydraulic consumer ( 10 ) is connected in the assignable supply line (A1). Circuit arrangement according to claim 1, characterized in that in parallel circuit ( 48 ) to the valve ( 40 ) and the measuring aperture ( 46 ) another aperture ( 50 ), which remains permanently fluid-conducting open and bypassing the valve ( 40 ) as well as the measuring aperture ( 46 ) a standby volume flow from the pressure supply port (P) to at least one of the hydraulic consumers ( 10 ). Circuit arrangement according to Claim 1 or 2, characterized in that the free opening cross-section of the metering orifice ( 46 ) is dimensioned significantly larger than the opening cross-section of the further diaphragm ( 50 ). Circuit arrangement according to one of the preceding claims, characterized in that in the case of inactive hydraulic consumers ( 10 . 12 . 14 ) the pressure in the load-sensing control line ( 42 . 44 ) via a relief diaphragm ( 52 ) is degraded, so that with the elimination of the actuating signal in the form of a hydraulic back pressure, the valve ( 40 ) closes. Circuit arrangement according to one of the preceding claims, characterized in that the valve ( 40 ) of the valve device is a hydraulically actuated directional control valve, which is preferably designed as a 2/2-way valve via a compression spring ( 41 ) is held in the non-actuated state in its blocking neutral position. Circuit arrangement according to one of the preceding claims, characterized in that in the supply line (A1) for the first hydraulic consumer ( 10 ) within the series connection a proportional valve ( 36 ), that, starting from this hydraulic consumer ( 10 ), whose return line (B1) into the feed line (A2) of the subsequent consumer in the series ( 12 ), in turn a proportional valve ( 36 ), and that this sequence for any subsequent, further hydraulic consumers ( 14 ) is maintained. Circuit arrangement according to one of the preceding claims, characterized in that between inlet (A1, A2, A3) and return line (B1, B2, B3) of each hydraulic consumer ( 10 . 12 . 14 ) a pressure balance ( 20 ) and that each pressure balance ( 20 ) on the input and output side to a common supply line ( 22 ) connected. Circuit arrangement according to claim 7, characterized in that the respective pressure compensator ( 20 ) on its opposite control sides once the supply pressure in the respective supply line (A1) of the hydraulic consumer ( 10 ) and once the load sensing pressure added to the pressure of an energy storage, such as a compression spring, has pending. Circuit arrangement according to one of claims 6 to 8, characterized in that the load tap ( 34 ) for detecting the current load-sensing pressure in the load-sensing control line ( 42 . 44 ) in the respective supply line (A1) between the proportional valve ( 36 ) and the hydraulic consumer ( 10 ), to which the load-sensing control line ( 42 . 44 ) connected. Circuit arrangement according to one of the preceding claims, characterized in that the actuating signal for the valve ( 40 ) of the valve device in the form of a control pressure from the load-sensing control line ( 42 . 44 ), which, contrary to the action of a compression spring ( 41 ) on the opposite control side of the valve piston of the valve ( 40 ) acts.

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