EP2855945B2 - Method for operating a hydraulic system - Google Patents

Description

The invention relates to a hydraulic system with a primary circuit controlling a first hydraulic consumer, which has a first hydraulic drive unit comprising at least one motor-driven hydraulic pump, with a secondary circuit controlling a second hydraulic consumer, which has a second hydraulic drive unit comprising at least one further motor-driven hydraulic pump has, wherein the hydraulic consumers arranged in the primary circuit and in the secondary circuit are supplied with hydraulic oil from a tank independently of one another via their hydraulic drive units in a first operating state, wherein in a second operating state when the first consumer is at a standstill, at least part of the hydraulic oil from the primary circuit into the Secondary circuit is fed to control the second consumer. With this measure, more oil is made available for the operation of the second consumer without increasing the speed of the motor-driven hydraulic pumps and thus a higher performance, in particular a higher operating speed, is achieved. A hydraulic system of this type is, for example, from EP 1 995 155 A2 known.

Hydraulic systems of this type are used, for example, to control and operate mobile thick matter pumps, which have a hydraulic drive mechanism for the thick matter pump arranged in the primary circuit and a hydraulic drive and control mechanism arranged in the secondary circuit for a distribution boom designed, for example, as an articulated mast. In the operating state of such a thick matter pump, preferably designed as a concrete pump, the drive mechanism of the thick matter pump and the placing boom is actuated simultaneously but independently of one another via their respective hydraulic pumps. The oil supply in the hydraulic circuits is limited by the amount of oil supplied by the associated hydraulic pumps. However, there are also operating states in which only one of the hydraulic circuits is activated. This is the case, for example, before and after a pumping process when unfolding and folding the placing boom between a folded transport position and an unfolded operating position. In modern concrete pumps, this unfolding and folding process is program-controlled. Since this process also means a waiting time for the pump driver, there is a need for rapid execution, which leaves something to be desired with the pump performance usually available in the mast hydraulic circuit.

Proceeding from this, the invention is based on the object of improving the known hydraulic system of the type specified at the outset in such a way that an increased operating speed is made possible for special tasks within the hydraulic system with a given pump power in the various hydraulic circuits.

In order to achieve this, the combination of features specified in claim 1 is proposed according to the invention. Advantageous refinements and further developments of the invention result from the dependent claims.

The object of the invention is achieved primarily in that the first consumer arranged in the primary circuit is expediently designed as a hydraulic drive mechanism of a thick matter pump, while the second consumer arranged in the secondary circuit is designed as a drive and control mechanism of a distribution boom consisting of several mast arms. In this case, the measure according to the invention can be used, for example, for the automatic folding and unfolding of the placing boom by feeding oil from the main circuit of the thick matter pump to the boom circuit, for example via a suitable valve control.

According to a preferred embodiment of the invention, the hydraulic drive mechanism of the thick matter pump has two hydraulic drive cylinders, each connected to a delivery cylinder via a piston rod, which at one end via a main line with the at least one hydraulic pump arranged in the primary circuit and at the other end via a rocking oil line are connected to one another, the primary circuit and the secondary circuit being connected to one another via a connecting line in which a first control valve which either releases or blocks the oil flow is arranged. In order to ensure the pressure build-up required for feeding into the secondary line, at least one second control valve which either blocks or releases the oil flow to the tank is expediently arranged within the primary circuit. A further embodiment variant provides that at least one third control valve is arranged within the primary circuit and either blocks or releases the oil flow to, from or between the hydraulic cylinders.

A further advantageous embodiment of the invention provides that at least one reversible and adjustable main pump as well as a feed pump opening into the primary circuit on the pressure side and into the tank on the suction side are arranged in the closed primary circuit. In this case, a first embodiment variant provides that the connecting line containing the control valve is branched off from one of the main lines of the primary circuit. So that the pressure required for the mast control can be built up by the main pump, the main pump is controlled in such a way that the pressure side of the main pump is on the relevant main line. Accordingly, in this case, the piston of the drive cylinder connected to the main line in question must be moved to its end position adjacent to the swing oil line. In another embodiment variant, this is The connecting line containing the control valve is connected to one of the main lines of the primary circuit via a check valve. This means that the main pump can be controlled in such a way that the pressure side is on either one or the other main line.

Furthermore, a control valve that releases or blocks the flow can be arranged in the swing oil line between the hydraulic cylinders. A further advantageous or alternative embodiment of this can consist in the fact that stroke compensation loops equipped with feed and feed valves are arranged in the area of the end positions of the drive cylinders, and that a control valve designed as a shut-off valve or a directional valve that can optionally be connected to the secondary circuit is arranged in at least one of the stroke compensation loops .

Fig. 1 bis 6

hydraulische Schaltungsanordnungen von Hydrauliksystemen mit einem geschlossenen Primärkreis zum Betätigen einer Zweizylinder-Dickstoffpumpe und einem Sekundärkreis für die Steuerung eines Verteilermasts;

Fig. 7 und 8

hydraulische Schaltungsanordnungen von Hydrauliksystemen mit offenem Primärkreis zum Ansteuern und Betätigen einer Zweizylinder-Dickstoffpumpe und mit einem Sekundärkreis für die Steuerung eines Verteilermasts. Diese Ausführungsbeispiele nach Fig. 7 und 8 fallen jedoch nicht unter den Schutz der Patentansprüche.

The invention is explained in more detail below with reference to the exemplary embodiments shown schematically in the drawing. Show it

Fig. 1 to 6

hydraulic circuit arrangements of hydraulic systems with a closed primary circuit for actuating a two-cylinder thick matter pump and a secondary circuit for controlling a distribution boom;

7 and 8

Hydraulic circuit arrangements of hydraulic systems with an open primary circuit for controlling and actuating a two-cylinder thick matter pump and with a secondary circuit for controlling a distribution boom. These exemplary embodiments Fig. 7 and 8th However, they are not protected by the patent claims.

The hydraulic circuits shown in the drawing are intended for thick material pumps which have two delivery cylinders, not shown, whose front openings open into a material feed container and can be alternately connected to a delivery line via a pipe switch during the pressure stroke. The delivery cylinders are driven in push-pull via hydraulic drive cylinders 7, 8, which are arranged in a first primary circuit I. For this purpose, the drive pistons of the drive cylinders 7, 8 are connected to the delivery pistons in the delivery cylinders via a common piston rod. The drive cylinders 7,8 form a first consumer in the primary circuit I, which also has a hydraulic drive unit comprising at least one motor-driven hydraulic pump 1,2. Furthermore, in all exemplary embodiments, a secondary circuit II is provided, which has a second hydraulic drive unit comprising a further motor-driven hydraulic pump 22. In a first operating state, the hydraulic consumers arranged in the primary circuit I and in the secondary circuit II can be supplied with hydraulic oil from a common tank 60 independently of one another via their hydraulic drive units. In this way, the primary circuit I with the drive cylinders 7, 8 and the secondary circuit II with the mast control 24 can be driven simultaneously, but separately from each other via their respective hydraulic pumps 1, 2, 22.

A special feature of the invention is that in a second operating state when the consumer comprising the hydraulic cylinders 7, 8 is at a standstill, at least part of the hydraulic oil can be fed from the primary circuit I into the secondary circuit II to control the placing boom. This measure ensures that the folding and unfolding of the distribution boom designed as an articulated boom can be carried out more quickly when the thick matter pump is at a standstill by supplying pressure oil from the primary circuit I. In order to achieve this, in all exemplary embodiments the primary circuit I and the secondary circuit II are connected to one another via a connecting line 29, in which a first control valve 28 which either releases or blocks the oil flow ( Fig. 1 to 4 , 6 to 8 ) or 35 ( Fig. 5 ) is arranged. In order to generate the pressure required for the feed in the primary circuit I, various design variants are proposed, which are explained in more detail below.

The exemplary embodiments according to Fig. 1 to 6 refer to hydraulic systems whose primary circuit I is designed as a closed hydraulic circuit. The drive cylinders 7 and 8 that form the consumer are driven in push-pull mode via the main lines 17, 18 via a reversible and adjustable main pump 1. This means that the piston 70 in the drive cylinder 7 extends when the piston 80 in the drive cylinder 8 is pushed back over the oil flowing in the rocking oil line 19. Once both pistons 70,80 in the drive cylinders 7,8 have reached their end position, the main pump 1 reverses its delivery direction so that the pistons move in the other direction. From the closed primary circuit I consisting of main pump 1, main lines 17, 18, drive cylinder 7, 8 and swing oil line 19, a corresponding amount of oil is always fed out into the tank 60, which is under atmospheric pressure, via the alternating flushing valve 5 and the pressure relief valve 6. The amount of oil to be discharged can be adjusted via the pressure relief valve 6. The alternating flushing valve 5 has two control lines 25, 26 connected to the main lines 17 and 18, which move the valve slide of the alternating flushing valve 5 back and forth, depending on which side the high pressure is on. Oil is then fed out from the low-pressure side to the tank 60 via the outlet lines 20 and 21 via the main lines 17 or 18. In addition, a feed pump 2 connected to the tank 60 on the suction side is provided, via which an amount of oil corresponding to the amount of oil fed out at the alternating flushing valve 5 is fed back into the low-pressure side of the main pump 1 via the check valves 3 and 4 connected to the main lines 17 and 18. Any excess quantity flows into the tank 60 via the pressure relief valve 43.

If the main pump 1 is at zero delivery, there is constant pressure in the lines 17 and 18, so that the valve slide of the alternating flushing valve 5 remains in the middle position and no oil is fed out. In this state, the entire amount of oil from the feed pump 2 flows into the tank 60 via the pressure relief valve 43.

Due to leaks occurring in the drive cylinders 7 and 8, oil must be fed in or out in certain operating conditions so that the pistons 70, 80 in question can reach their end positions. For example, if the piston 80 in the cylinder 8 does not reach its bottom-side end position while the piston 70 in the cylinder 7 has reached its rod-side end position, oil can be supplied to the cylinder 8 via the throttle 16, the check valve 13 and the rocking oil line 19, so that the Piston 80 in cylinder 8 reaches its bottom end position. On the other hand, if the piston 70 in the cylinder 7 has not yet reached its rod-side end position, while the piston 80 in the cylinder 8 is already in its bottom-side end position, oil is fed off via the check valve 11 so that the piston 70 in the cylinder 7 reaches its rod-side end position can drive. The piston end position valve 10, which is designed as a ball valve, must be open. The check valve 12 on the bottom side corresponds to the check valve 11 on the side of the cylinder 8, while the piston end position valve 10 corresponds to the piston end position valve 9 there. On the other hand, the check valve 14 on the cylinder 8 corresponds to the rod-side check valve 13 on the cylinder 7, while the rod-side throttle 16 corresponds to the throttle 15 there. The secondary circuit II, designed as a mast circuit, contains a hydraulic pump 22, which can either be designed as a constant or variable pump. The hydraulic pump 22 is connected on the suction side to the tank 60 and on the pressure side via the pressure line 23 to the consumer designed as a mast control 24.

In the exemplary embodiments according to Fig. 1 to 4 and 6 to 8 A control valve 28 designed as a 2/2-way valve is provided in the connecting line 29 between primary circuit I and secondary circuit II. In the rest position, the directional control valve 28 shuts off the connection between the primary circuit I and the pressure line 23 without leaking oil, while in the switched position the connection is switched on. So that the pressure necessary for the mast control 24 can be built up by the main pump 1, the main pump 1 is controlled in such a way that in the case of Fig. 1 on the main line 17 is the pressure side. Therefore, the piston 70 of the drive cylinder 7 must be moved into its rod-side end position. Since the primary circuit I is opened when feeding to the secondary circuit II (mast circuit) and the oil fed to the secondary circuit II no longer flows back to the main pump 1, only as much oil can be fed in as the feed pump 2 supplies. The maximum possible quantity can be limited via the electrically proportional (EP) quantity adjustment 27 of the main pump 1.

In the exemplary embodiment according to Fig. 2 Two additional check valves 30 and 31 are provided, via which a connection from the main lines 17 or 18 to the directional control valve 28 can be established. As a result, the main pump 1 can be selectively controlled in such a way that the pressure side is either on the main line 17 or on the main line 18. If the pressure side is on the main line 18, the piston in the drive cylinder 8 must be moved to its rod-side end position.

In the exemplary embodiment according to Fig. 3 an additional control valve 32 designed as a shut-off valve is provided, which in the non-activated state leads the oil fed out via the alternating flushing valve 5 and the pressure relief valve 6 to the tank 60. The control valve 32 is activated to feed the secondary circuit II (mast circuit). This blocks the connection to tank 60 so that no more oil can be fed out to tank 60. This means that the entire amount of oil from the feed pump 2 is available via the main pump 1 for supply to the secondary circuit II.

In the case of the exemplary embodiment Fig. 4 an additional shut-off valve 34 is provided between the throttle 16 and the check valve 13 of the stroke compensation loop. If the piston 70 in the drive cylinder 7 is in its rod-side end position and pressure is built up due to the feed to the secondary circuit II (mast circuit), oil flows from the main line 17 via the throttle 16, the connecting line 19 and the check valves 13, 11 to the low-pressure side 18 This oil is therefore not available for feeding to the fattening circuit. When not activated, the valve 34 is open. If the valve 34 is activated, no more oil can flow out and the entire amount of oil from the feed pump 2 is available for feeding into the secondary circuit.

In the exemplary embodiment according to Fig. 5 Instead of the control valve 28, a control valve 35 designed as a directional control valve is alternatively provided in the stroke compensation loop of the cylinder 7. When not activated, oil can flow via the throttle 16 and the check valve 13. If the directional control valve 35 is activated and the piston 70 in the drive cylinder 7 is in its rod-side end position, a connection is made between the main line 17 via the drive cylinder 7 and the line 29 with the pressure line 23 of the secondary circuit II (mast circuit). At the same time, the feed to the low-pressure side is blocked via the throttle 16 and the check valve 13. This means that no more oil can flow out, so that the entire amount of oil from the feed pump 2 is available for supply.

In the case of the exemplary embodiment Fig. 6 an additional shut-off valve 33 is provided in the swing oil line 19. In the uncontrolled state The shut-off valve 33 connects the drive cylinders 7 and 8 so that they can carry out the delivery cycle described above. If the shut-off valve 33 is activated, the connection through the rocking oil line 19 is blocked, so that the pistons 70,80 can no longer move in the drive cylinders 7,8. The oil compensation can no longer take place due to the leakage in the drive cylinders 7,8. As a result, the piston 70,80 pressure can be built up in the drive cylinders 7,8 and in the main lines 17,18 by the main pump 1 in any position. The pressure relief valve 52, which is connected via the check valves 53 and 54 to the pressure chambers between the drive cylinders 7, 8 and the shut-off valve 33, prevents unacceptably high pressures when the shut-off valve 33 is closed, which could occur due to the pressure transmission in the drive cylinders 7, 8.

In the exemplary embodiments Fig. 7 and 8th an open primary circuit I is provided to drive the concrete pump. In case of Fig. 7 the main pump 44 sucks the oil directly from the tank 60 via the suction line 48. Between the main line 47 and the working lines 17 'and 18' there is a reversing valve 36, which either connects the main line 47 with the working line 17' or 18' and not connected line 18 'or 17' connects to the tank 60. The pistons 70,80 in the drive cylinders 7 and 8 then move in push-pull as described above. To reverse the direction of movement, the reversing valve 36 is controlled in the opposite direction. The main pump 44 has an electrically proportional (EP) adjustment device 45. In the case of Fig. 7 If hydraulic oil is supplied to the secondary circuit II (mast circuit), the valve 36 is not activated. This means that the connection between the main line 47 and the working lines 17', 18' is blocked. If the directional control valve 28 is now activated, oil from the primary circuit I can be fed to the secondary circuit II via the main line 47 and the line 29. Theoretically, the entire delivery volume of the main pump 44 can be fed to the secondary circuit II. In practice, the amount of oil supplied is adjusted via the electrically proportional quantity adjustment 45.

In the exemplary embodiment according to Fig. 8 Alternatively, both the mast pump 22 with controller 37 and the main pump 44 with controller 46 (load-sensing LS) are LS-controlled. A directional control valve 38 is provided here, via which either the load pressure of the drive cylinders 7, 8 reported via line 41 or the load pressure of the mast control reported via line 42 is fed to the load sensing controller (LS) 46 of the main pump 44. With LS-controlled hydraulic pumps, the high pressure of the hydraulic pump is compared with the load pressure and the difference between the two pressures is kept constant via an adjusting element. The adjusting element ensures that the amount of oil is independent of the load pressure. The load pressure of the drive cylinders 7, 8 is picked up via the shuttle valve 37 either from the working line 17 'or 18'. If the directional control valve 38 is not activated, the load pressure of the drive cylinders 7 and 8 goes to the controller 46 of the main pump 44. This regulates the pressure difference at the adjusting throttle 50, with which the speed of the pistons 70, 80 in the drive cylinders 7 and 8 are adjusted regardless of the load pressure can. If hydraulic oil from the primary circuit I is to be fed to the secondary circuit II, the load pressure of the mast control is reported to the controller 46 of the main pump 44 by activating the valve 38 via line 42. This regulates the pressure difference at the adjusting throttle 51, independent of the load pressure, with which the amount of hydraulic oil supplied can be adjusted.

The invention has been described in detail above for the application of a mobile two-cylinder thick matter pump. In principle, it is possible to transfer the principle on which the invention is based to other hydraulic systems with at least two hydraulic circuits, such as those found, for example, in excavators or other work machines.

In summary, the following should be noted: The invention relates to a hydraulic system, preferably for controlling and actuating a mobile thick matter pump. The hydraulic system comprises a primary circuit I which controls a first hydraulic consumer and which has a hydraulic drive unit comprising at least one motor-driven hydraulic pump 1, 2, 44. Furthermore, a secondary circuit II controlling a second hydraulic consumer is provided, which has a second hydraulic drive unit comprising at least one further motor-driven hydraulic pump 22. In a first operating state, the hydraulic consumers 7, 8; 24 arranged in the primary circuit I and in the secondary circuit II can be supplied with hydraulic oil from a common tank 60 independently of one another via their hydraulic drive units. A special feature of the invention is that in a second operating state when the first consumer 7,8 is at a standstill, at least part of the hydraulic oil is fed from the primary circuit I into the secondary circuit II to control the second consumer 24. Advantageously, the first consumer 7, 8 arranged in the primary circuit I is designed as a hydraulic drive mechanism of the thick matter pump, while the second consumer 24 arranged in the secondary circuit II is designed as a drive and control mechanism of a distribution boom consisting of several mast arms.

Reference symbol list

1

Main pump (hydraulic pump)

2

Feed pump (hydraulic pump)

3

check valve

4

check valve

5

Alternating flush valve

6

Pressure relief valve

7

Drive cylinder

8th

Drive cylinder

9.10

Piston end valve

11,12

check valve

13,14

check valve

15,16

throttle

17

main line

18

main line

17'

Work management

18'

Work management

19

Rocking oil line

20

Exit line

21

Exit line

22

Mast pump (hydraulic pump)

23

pressure line

24

Mast control

25

Control line

26

Control line

27

Quantity adjustment

28

Control valve (2/2-way valve)

29

connecting line

30

check valve

31

check valve

32

control valve

33

Shut-off valve

34

Shut-off valve

35

control valve

36

reversing valve

37

Shuttle valve

38

Directional valve

41

Line

42

Line

43

Pressure relief valve

44

Main pump (hydraulic pump)

45

Adjustment device (quantity adjustment)

46

Load sensing controller (LS)

47

main line

48

suction line

50

Variable throttle

51

Variable throttle

52

Pressure relief valve

53

check valve

54

check valve

60

tank

70

Pistons

80

Pistons

I

Primary circuit

II

Secondary circuit

Claims (8)

1. A hydraulic system having a closed primary circuit (I) which activates a first hydraulic consumer (7, 8) and has a first hydraulic drive assembly which comprises at least one motor-driven, reversible and adjustable hydraulic pump (1, 2, 44) and a feed pump (2) which opens on the pressure side into the primary circuit (I) and on the suction side into the tank (60), having a secondary circuit (II) which activates a second hydraulic consumer (24) and has a second hydraulic drive assembly which comprises at least one further motor-driven hydraulic pump (22), the hydraulic consumers which are arranged in the primary circuit (I) and in the secondary circuit (II) being loaded in a first operating state via their hydraulic drive assemblies independently of one another with hydraulic oil from a tank (60), and, in a second operating state, when the first consumer (7, 8) is at a standstill, at least part of the hydraulic oil from the primary circuit (I) being fed into the secondary circuit (II) in order to activate the second consumer (24), characterized in that the first consumer (7, 8) which is arranged in the primary circuit (I) is configured as a hydraulic drive mechanism of a thick matter pump, whereas the second consumer (24) which is arranged in the secondary circuit (II) is configured as a drive and control mechanism of a distributor boom of the thick matter pump, which distributor boom consists of a plurality of boom arms, wherein in the second operating state, when the hydraulic pump (22) in the secondary circuit is operating, the hydraulic oil is supplied via the feed pump (2), such that the unfolding and folding of the distributor boom can be carried out more rapidly while the thick matter pump is at standstill.
2. The hydraulic system as claimed in claim 1, characterized in that the hydraulic drive mechanism of the thick matter pump has two hydraulic drive cylinders (7, 8) which are connected via in each case one piston rod to a delivery cylinder and are connected at their one end via in each case one main line (17, 18) to the at least one hydraulic pump (1, 2)which is arranged in the primary circuit (I) and are connected at their other end via an oil oscillation line (19) to one another, and in that the primary circuit (I) and the secondary circuit (II) are connected to one another via a connecting line (29), in which a first control valve (28, 35) which selectively releases or shuts off the oil flow is arranged.
3. The hydraulic system as claimed in claim 2, characterized in that at least one second control valve (5, 32, 36) which selectively shuts off or releases the oil flow to the tank is arranged within the primary circuit (I).
4. The hydraulic system as claimed in claim 2 or 3, characterized in that at least one third control valve (33, 36) which selectively shuts off or releases the oil flow to, from or between the hydraulic cylinders is arranged within the primary circuit (I).
5. The hydraulic system as claimed in claim 2, characterized in that the connecting line (29) which contains the control valve (28) is branched off from one of the main lines (17) of the primary circuit (I).
6. The hydraulic system as claimed in claim 2, characterized in that the connecting line (20) which contains the control valve (28) is connected via in each case one non-return valve (30, 31) to one of the main lines (17, 18) of the primary circuit (I).
7. The hydraulic system as claimed in one of claims 2 to 6, characterized in that a control valve (33) which releases or shuts off the throughflow is arranged in the oil oscillation line (19) between the hydraulic cylinders.
8. The hydraulic system as claimed in one of claims 2 to 7, characterized in that stroke compensation loops which are fitted with infeed and outfeed valves are arranged in the region of the end positions of the pistons (70, 80) in the drive cylinders (7, 8), and in that a control valve (34) which is configured as a shut-off valve or a directional valve (35) which can be connected selectively to the secondary circuit (II) is arranged in at least one of the stroke compensation loops.

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