DE3245288A1 - METHOD FOR SAVING ENERGY WHEN SETTING AN EQUIPMENT CYLINDER ON A HYDRAULIC EXCAVATOR BY A HYDRAULIC CIRCUIT - Google Patents

Description

O&K Orenstein & Koppel Aktiengesellschaft

Berlin

PAT 2o44

Method of saving energy in placing an equipment cylinder on one Hydraulic excavator through a hydraulic circuit

The invention relates to a method of saving of energy when placing an equipment cylinder on a hydraulic excavator through a hydraulic circuit with at least One pumping unit, one collecting unit and one working fluid control element.

The lowering of the boom and the stick of the equipment of an excavator was previously carried out by feeding under. More pressure Liquid into the working spaces of the corresponding equipment cylinders carried out. This fact did not take into account that both in the boom and in the stick of the dredging equipment potential energies are available that can be used for these operations or support them could.

The object of the invention is therefore that on the boom and on the stick of the equipment of an excavator

acting external forces, in particular the potential energy present in them, for the transport of the To utilize working fluid in the cylinder spaces of the corresponding equipment cylinder.

The task is in a method described at the beginning solved in that when lowering a piece of equipment by the equipment weight under pressure from the piston side Working fluid emerging from the cylinder chamber is fed to the cylinder chamber on the rod side.

In order to carry out the above method, a hydraulic circuit for setting an equipment cylinder is also used on a hydraulic excavator, its piston and rod side Cylinder space via working fluid lines and a working fluid actuator are connected to a pump and a collecting unit, indicated in the invention in .One selectable from several switching positions of the working fluid control element within its switching section when the supply line from the pump unit is blocked and more permeable Connection from the cylinder space on the rod side to the collecting unit, another permeable connection from the piston side Cylinder space is provided for the above connection of the rod-side cylinder space with the collecting unit.

- 1o -

Another hydraulic circuit for carrying out the inventive method for setting an equipment cylinder on a hydraulic excavator, the piston-side and rod-side cylinder space via working fluid lines and a working fluid control element can be connected to a pumping unit and a collecting unit, and in the case of three or more Selectable, controllable switching positions of the working fluid control element at least the following line assignments can represent

1. a) Passage from the pump unit to the piston side

Cylinder space,

b) Return from the cylinder chamber on the rod side to the collecting unit,

2. a) Run blocked,
b) return blocked,

3. a) Passage from the pump unit to the rod-side

Cylinder space,

b) Return from the cylinder chamber on the piston side to the collecting unit

is seen according to the invention that between the working fluid lines from the piston and rod side

Cylinder space to the working fluid control element in a connecting line a controllable lowering valve is provided, parallel to the downstream part of the connecting line to the working fluid line of the rod-side A discharge line to the collecting unit is provided in the cylinder space via a downstream preload valve.

A schematic exemplary embodiment of the invention will be explained with the aid of a drawing. The same parts have the same reference numerals in the individual figures of the drawing.
It show the

Fig. 1 to 3 hydraulic circuit embodiments of a first and the

4 and 5 hydraulic circuit designs of a second hydraulic circuit to carry out the inventive method.

Figure 1 shows a basic circuit for lowering equipment parts / in which an equipment cylinder 1 is shown, its piston-side cylinder space 2 and its Rod-side cylinder space 3 via unspecified

BATH ORIGINAL

Working lines and a working fluid actuator can be connected to a pumping unit 5 and a collecting unit 6. Member 4 can assume three selectable controllable switch positions, with at least the following line assignments are representable.

1. a) Passage from the pump unit to the piston side

Cylinder space,

b) Return from the cylinder chamber on the rod side to the collecting unit,

2. a) Run blocked,
b) return blocked,

However, the aforementioned line assignments can also be supplemented by others. Essential for the hydraulic circuit it is that in a selectable, of several switching positions of the working fluid control element 4 within its switching section with the feed line blocked from the pump unit 5 and the permeable connection 7 from the rod-side Cylinder space 3 to the collecting unit 6 is another permeable connection 8 from the cylinder space on the piston side

provided for the above permeable connection 7 of the rod-side cylinder space 3 with the collecting unit 6 is. '

Experience has shown that there are higher line resistances to the consumer than are to be expected for the collecting unit 6 is between the connection of the further permeable connection 8 to the permeable connection 7 and the outlet of the working fluid to the collecting unit 6 in the permeable Connection 7 a preload valve 11 is provided.

The hydraulic circuit described in Figure 1 must be exceeded when the dead center position, d. H. in the absence abandoned the external force on the equipment cylinder will..

FIG. 2 shows a hydraulic circuit with an automatic switchover to normal operation Use of an external switch valve 12 and one Check valve 13. The check valve is between the connection 9 of the further permeable connection 8 to the permeable connection 7 and the inlet 14 of the working fluid from the cylinder space on the rod side 3 installed with a blocking effect to the connection 9 of the further permeable connection 8 to the permeable connection 7.

BATH ORIGINAL

In parallel with the working fluid actuator 4, d. H. this immediately in a bypass line 15 is the pump unit 5 is connected to the cylinder space 3 on the rod side. The switching valve arranged in the bypass line 15 12 is on with its control input 16 via a control line 22 directly or indirectly via a line part the piston-side cylinder chamber 2 is connected. In this way it is possible to use the cylinder pressure acting on the piston side as a switching signal. He goes on reaching the Dead center, d. H. in the absence of the action of external forces, e.g. B. gravity, on the pieces of equipment to zero. The switching valve 12 shown must have at least the following can make two line assignments realizable.

1st pass of the pump unit 5 to the cylinder chamber 3 on the rod side.

2nd run blocked.

However, switching valves can also be used which allow further switching positions, and it is also equally possible from the control line 22 than for the switching action relieves pressure, a connection

BATH ORIGINAL

to lead to the opposite side of the control input 16 on the switching valve 12, so that the spring recognizable at the switching valve only has to overcome the frictional resistance and works without pressure.

FIG. 3 shows a control of the switching valve 12 in such a way that the control input 16 is connected via a separate control line 17 to a working connection 18 of a solenoid valve. For the further work ports 2oa 2ob and the solenoid valve 19 j _e are a conduit 21a and 21b to the pump unit 5 and for Samme! Unit 6 is provided "

The functional sequence in the equipment cylinder 1 using the hydraulic circuits as shown in FIGS. 2 and 3 are reproduced is as follows:

The working fluid actuator is used to extend the equipment cylinder 4 brought into a switching position, which has the following line assignments.

1. Connection of the pump unit 5 with the piston-side Cylinder space 2 and

2, connection of the rod-side cylinder space with the Collection unit 6.

The working fluid, conveyed by the pump unit 5, then acts on the piston area in the cylinder space, and that in the cylinder size on the rod side. displaced liquid volume enters the collecting unit 6 unhindered.

To retract the equipment cylinder, the working fluid actuator changes in a Sghal determination made by the detailed Sehaltstellung the working fluid control element 4 corresponds. It corresponds to the connections as they are in the right switching section of the working fluid control element 4 are shown. The external force acting on the piston rod creates a reaction pressure on the piston surface and in the piston-side cylinder space 2, via the control line 22 a switchover of the switchover valve 12 causes so that the external connection from the pumping unit to the rod-side cylinder chamber 2 is blocked. It is also the connection from the pump unit to the rod-side Cylinder space 2 in the working fluid control element 4 interrupted. The volume of liquid displaced from the piston-side cylinder chamber 2 only partially reaches the Pre-loading valve 11 to the collecting unit 6, since the pressure set on the pre-loading valve 11 is higher than the line resistance to the cylinder chamber on the rod side, and this is given priority.

BATH ORIGINAL

When the dead center is reached, the equipment movement is absent the external force and consequently also the reaction pressure from the piston-side cylinder space via the control line 22 to the control input 16 of the switching valve. It therefore switches the spring shown the switching valve 12 in the line allocation, Passage from the pump unit 5 to the rod-side Cylinder space, to which the pump unit then delivers. It is the connection to the collecting unit 6 through the check valve 13 blocked. The working fluid from the piston-side cylinder space 2 reaches the collecting unit 6 via the preload valve 11.

Are with such a circuit now for other reasons If electrical command pulses are present anyway, this can be used by, as shown in Figure 3, the Switching valve 12 controls via a solenoid valve 19.

Furthermore, a make-up line 23 can be seen in FIG. 3, which is switched via a forward direction Make-up line check valve 24 can feed into the piston-side cylinder space 2.

Finally, Figure 3 leaves one for safety reasons provided for the equipment cylinders of dredging equipment

BATH ORIGINAL

pilot operated secondary pressure relief valve 25 with the corresponding upper pilot valve 26 and the lower pilot valve 27 and another solenoid valve 28 recognize. The terms upper and lower each refer to a pilot valve relate to the pressure values or pressure ranges in which they control the secondary pressure limiting valve 25. Lines from this hydraulic diagram to the collecting unit 6 are not designated in more detail.

In the context of the requirements that are important in practice, such as those of consumers, i. H. of people working with excavators, are set up, a functional behavior in the "floating position" is also for excavator equipment he wishes. This term includes the possibility of changing the position of the dredging equipment when exposed to external forces Powers. From a practical point of view, it is required that the equipment be attached to the equipment handle under the action of gravity, and of the equipment in particular Shovel, approach the subgrade or come to rest on this, and that this shovel but also the equipment when forces act, due to uneven floors, can lift against the direction of gravity.

Based on a hydraulic circuit as shown in Figure ** ■ is shown, the aforementioned floating position realize as follows. In the first case that the boom z. B. due to its gravity, should be able to retract, it is assumed that the connection from the pump unit 5 to the rod-side cylinder chamber 3 is locked externally and internally. This is the case when the working fluid actuator 4 is brought into the right switch position. It then pushes the external load in the direction of retraction of the equipment cylinder, and it becomes the working fluid conveyed from the piston-side cylinder chamber 2 via the check valve 13 into the rod-side cylinder chamber 3. A part of the liquid volume from the piston-side cylinder space 2 becomes the collecting unit via the preload valve 11 discharged. This is necessary because the total volume of the piston-side cylinder space 2 is greater than that of the rod-side cylinder space 3.

The second case of an external force also contrary to the The direction of gravity, for example due to an unevenness in the floor, can also be implemented as follows.

With a signal for the working fluid actuator 4, that brings this into the position already described above is also a signal for the further solenoid valve 28

ΘΑΟ ORIGINAL

- 2ο -

submitted. This is the pilot operated secondary pressure relief valve 25 set via the low pilot valve 27 to a low pressure range. Working fluid can thus from the rod-side cylinder chamber 3 via the secondary pressure relief valve 25 escape to the collecting unit 6. A corresponding volume of working fluid for the piston-side Cylinder chamber 2 flows in via the make-up line 23 and the make-up line check valve 24. By the free Possibility of flow of the working fluid between the cylinder spaces the equipment position is not clamped, but versatile.

Finally, for the hydraulic circuit shown in FIG. 3, the case is explained in which the equipment cylinder is retracted takes place under the action of the pump unit 5. It is the working fluid control element 4 is again in the right switching position already explained. There is also a special signal from an external command generator given to the solenoid valve 19, which simultaneously sends a clear signal represents for the further solenoid valve 28. So is the secondary pressure relief valve 25 via the upper pilot valve 26 activated, so that this represents a pressure limitation at maximum pressure. By electrical activation of the solenoid valve 19 and thus the switching valve 12, the pump unit 5 promotes via the bypass line 15 and the Switching valve 12 working fluid into the rod-side cylinder chamber 3. The working fluid from the piston-side

BATH

Cylinder chamber 2 reaches the preload valve 11 Collection unit 6.

In the figure 4 is another hydraulic circuit for Solution of the problem according to the inventive method shown, which is suitable for placing an equipment cylinder 1 on a hydraulic excavator whose Piston-side and rod-side cylinder space 2, 3 via working f fluid lines and a working fluid actuator 4 with a pump and a collecting unit 5, can be connected and in which three or more can be selectively controlled Switch positions of the working fluid actuator 4 represent at least the following line assignments can.

1. a) Passage from the pump unit 5 to the piston side

Cylinder space 2,

b) Return from the rod-side cylinder space 3 to the collecting unit 6,

2. a) Run blocked,
b) return blocked,

BAO ORIGINAL

3. a) Passage from the pump unit 5 to the rod-side Cylinder space 3,

b) Return from the piston-side cylinder space 2 to the collecting unit 6.

It is essential to the invention that a controllable lowering valve 31 is provided in a connecting line 3o between the working fluid lines 29a, 29b from the piston- and rod-side cylinder space 2, 3 to the working fluid actuator 4, parallel to the downstream part of the connecting line to the working fluid line 29b of the rod-side cylinder space 3, a discharge line 33 to the collecting unit 6 is provided via a downstream preload valve 32. It can also be seen that in the downstream and parallel connected part of the connecting line, a non-return valve 34, likewise connected downstream with respect to the working fluid control element, with a flow direction to the working fluid line 29b is installed.

The working fluid control element 4 is shown with control connections 35a and 35b, as is the lowering valve

BATH ORIGINAL '

has a lowering valve control input 36. The latter and the control terminal 35b are from the working outputs a switchover slide 37 controlled. Figure -5 shows a variant in the hydraulic circuit of Figure 4 insofar as than that the lowering valve 31 is replaced by a modified lowering valve 38, so that in this sequence the recognizable parallel connection in the downstream part of the connection line 3o can already be carried out by means of the modified lowering valve 38. It is then no longer necessary to provide an element corresponding to the downstream check valve 34 of FIG.

Ultimately, it can be seen in the figure that with connection to the piston-side cylinder space 2 has an additional feed line 39 and an additional check valve 4o are.

The functioning of the hydraulic circuits according to the figures and FIG. 5 is as follows for the individual operations of the equipment cylinder.

The extension of the equipment cylinder 1 requires a line allocation in the working actuator 4, in which the pump unit 5 with the piston-side cylinder chamber 2 and the

BADORIQiNAL,. '. ■

Rod-side cylinder space 3 with the collecting unit 6 are connected »This corresponds to a position of the working fluid control element 4, as it is in the left switch position, immediately adjacent to the control connection 35a, is reproduced.

When retracting the equipment cylinder under the action of an external force, e.g. B. the load of the dredging equipment, the switchover slide 37 is in the position shown without a switching pulse, and a control signal is sent to the. Lowering valve control input 36, which opposes the lowering valve to the one shown Brings a position in which a flow from the piston-side cylinder chamber 2 via the lowering valve 31 to the downstream check valve 34 and via the working fluid line 29b to the cylinder chamber on the rod side 3 is possible. At the same time, part of the working fluid then flows out of the piston-side cylinder space 2 Via the downstream preload valve 32 and the discharge to the collecting unit 6. If the excavator equipment comes as a result one edition to rest, the equipment cylinder stops. The further retraction, now without any external force, requires a switching pulse at the input of the switchover slide

so that it goes into the other switch position. So is when an active signal for the lowering valve control input is interrupted 36 given a signal for the control connection 35 b of the working fluid actuator 4, so that there is a assumes changed switching position, which corresponds to that of the right chamber in the immediate vicinity of the control connection 35b. It is then the pump unit 5 via the working fluid control element 4 and the working fluid line 29b is connected to the rod-side cylinder space 3 and at the same time the working fluid escapes from the piston-side cylinder chamber 2 via the working actuator into the collecting unit 6.

A particularly simple implementation for the function of the floating position of the dredging equipment is through the modified hydraulic circuit according to Figure 5 possible.

The extension of the equipment cylinder and its retraction are carried out by switching operations that correspond to those which were explained in connection with the hydraulic circuit of FIG.

In order to achieve a floating position for the dredging equipment, a signal command is given to the lowering valve control input 36 after activating the switching slide 37 in a position that corresponds to that shown, so that the lowering valve 38 goes into a position in which, however, connections within the lowering valve are made as they are in the right ventricle next to the
Lowering valve control input 36 are shown. The lowering valve 38 then connects the piston-side cylinder space with the rod-side cylinder space 3 via the working fluid line 29b. The equipment cylinder 1 moves in this position of the hydraulic circuit up to the
Level and remain in this position. As a result of other work movements, starting from the subgrade and associated forces, a force can be exerted on the equipment cylinder in the direction that it follows. The connection described above enables the working fluid to flow freely between the cylinder spaces.

@AD

The aforementioned floating position is canceled and the equipment cylinder 1 is clamped by removing it the predetermined signal at the lowering valve control input 36 ,. A new signal is given to the input of the switchover slide 37, causing it to change to the not shown Position switches and a signal to the control terminal 35b of the working fluid actuator 4 leads. It is thus a switching position of the working fluid control element 4 produced in which the pump unit 5 via the working fluid line 29b into the cylinder space on the rod side 2 promotes, and the equipment cylinder 1 retracts positively.

It is easily possible to route the hydraulic signals to the control connections 35a and 35b and also for the lowering valve control input 36 to be replaced by mechanical, pneumatic or electrical signal lines. The hydraulic circuits shown also suffer no limitation in that the equipment cylinder 1 is made of a parallel connection several individual equipment cylinders is shown.

The hydraulic circuits shown are also applicable in the event that the equipment cylinder is the boom cylinder of dredging equipment, and they can too be realized for the stick cylinder of the excavator equipment,

Designation of the reference numbers

1 equipment cylinder

2 piston-side cylinder space

3 rod-side cylinder space

4 working fluid actuator

5 pumping unit

6 collection unit

'7 permeable connection

8 more permeable connection

9 connection

10 outlet

11 preload valve

12 changeover valve

13 check valve

14 inlet

15 bypass line

16 control input

17 separate control line

18 Working connection

19 solenoid valve

2oa further work connection

21a line

22 control line

23 Make-up line

24 Make-up line check valve

25 secondary pressure relief valve

BATH ORIGINAL

26 upper pilot valve

27 low pilot valve

28 further solenoid valve

29a working fluid line 29b "

30 connecting cable

31 lowering valve

32 downstream preload valve

33 Derivation

34 downstream check valve 35a control connection

36 Lowering valve control input

37 Toggle slide

38 modified lowering valve

39 additional make-up line

40 additional check valve

Claims (20)

O&K Orenstein & Koppel Aktiengesellschaft Berlin " PAT 2o4 4 PATENT CLAIMS 1 / Method of saving energy when placing a Equipment cylinder on a hydraulic excavator by a hydraulic circuit with at least one pump unit each, a collective unit and working fluid control element, characterized in that when a piece of equipment is lowered by the weight of the equipment under pressure working fluid emerging from the piston-side cylinder space (2) the rod-side cylinder space (3) is fed. 2. The method according to claim 1, characterized in that after a reduction in the pressure on the working fluid in the piston-side cylinder space (2) a selectable specific value range a further setting of the equipment cylinder (T) by the Pump unit (5) delivered working fluid takes place. 3. The method according to claim 2, characterized in that the selectable value range is approximately equal to zero. BAD ORKSfNAt 4. Hydraulic circuit for performing a method according to claims 1 to 3 and for setting an equipment cylinder on a hydraulic excavator, whose cylinder chamber on the piston and rod side is connected to working fluid lines and a working fluid control element can be connected to a pumping unit and a collecting unit, characterized in that in one of several switch positions of the working fluid actuator that can be selected (4) within its switching section when the supply line from the pump unit (5) is blocked and more permeable Connection (-7), from the rod-side cylinder space (3) to the collecting unit (6) another permeable Connection (8) from the piston-side cylinder space (2) to the protruding connection of the rod-side cylinder space (3) is provided with the collecting unit (6). 5. Hydraulic circuit according to claim 4, characterized in that between the connection (9) of the further permeable connection (8) to the permeable connection (7) and the outlet (1o) of the working fluid A preload valve (11) is provided for the collecting unit (6) in the permeable connection (7). 6. Hydraulic circuit according to claim 5, characterized in that that between the connection (9) of the further permeable connection (8) to the permeable connection (7) and the inlet (14) of the working fluid, a check valve from the cylinder chamber (3) on the rod side (13) is provided with a blocking effect for the connection (9) of the further permeable connection (8) to the permeable connection (7). 7. Hydraulic circuit according to claim 6, characterized in that parallel to the working fluid actuator (4) a bypass line (15) with a switching valve (12) is provided, which connects the pump unit (5) connects to the rod-side cylinder space (3). 8. Hydraulic circuit according to claim 7, characterized in that that the control input (16) of the switching valve (12)
tils is connected to the piston-side cylinder chamber (2) via a control line (2 2). 9. Hydraulic circuit according to claim 6, characterized in that that the control input (16) of the switching valve (12) via a separate control line (17) with a working connection (18) of a solenoid valve (19) connected is. BATH ORIGINAL 10. Hydraulic circuit according to claim 9, characterized in that that for the other working connections (2oa, 2ob) of the solenoid valve (19) each have a line (21a, 21b) to the pumping unit (5) and collecting unit (6) are provided. 11. Hydraulic circuit according to claim 6, characterized in that on the rod-side cylinder space (3) a secondary pressure relief valve (25) is connected. 12. Hydraulic circuit according to claim 11, characterized in that that the pressure relief valve (25) with two selectable specific pressure ranges permeability property having. 13. Hydraulic circuit according to claim 12, characterized in that that the pressure ranges can be set differently by a factor of about 1o. 14. Hydraulic circuit according to claim 6, characterized in that that to the piston-side cylinder space (2) via a make-up line check valve switched in the flow direction (24) a Nachspeiseleituna (23) is connected. 15. Hydraulic circuit for carrying out a method according to claims 1 to 3 and for setting an equipment cylinder on a hydraulic excavator, whose cylinder chamber on the piston and rod side is connected to working fluid lines and a working fluid control element can be connected to a pump unit and a collection unit are and in the three or more selectable controllable switching positions of the working fluid control element can display at least the following line assignments: 1. a) Passage from the pump unit to the piston side Cylinder space, b) Return from the rod-side cylinder space to Collecting unit, 2. a) Run blocked,
b) return blocked, 3. a) Passage from the pump unit to the rod-side Cylinder space, b) Return from the cylinder chamber on the piston side to the collecting unit, characterized in that between the working fluid lines (29a, 29b) from the piston and rod side BAD ORIGINAL Cylinder space (2, 3) for setting the working fluid member (4) in a connecting line (3o) a controllable lowering valve (31) is provided, wherein parallel to the downstream part of the connecting line (3o) to the working fluid line (29b) of the rod-side cylinder space (3) via a downstream preload valve (32) a discharge line (33) to the collecting unit (6) is provided. 16. Hydraulic circuit according to claim 1, characterized in that that in the downstream and parallel connected part of the connecting line (3o) a downstream Check valve (34) with flow direction to the working fluid line (29b) is provided. 17. Hydraulic circuit according to claim 15 and 16, characterized characterized in that the control connections (35a, 35b) of the working fluid actuator (4) and the Lowering valve control input (36) of the lowering valve (31) with the work outputs of a switchover slide (37) are connected. 18. Hydraulic circuit according to claim 4 and claim 15, characterized in that the equipment cylinder (1) consists of the parallel connection of several individual equipment cylinders is constructed. 19. Hydraulic circuit according to claim 4 and claim 15, characterized in that the equipment cylinder (1) is represented by a boom cylinder. 20. Hydraulic circuit according to claim 4 and claim 15, characterized in that the equipment cylinder (1) is represented by a stick cylinder.