WO2013164072A1

WO2013164072A1 - Device for saving energy in working appliances that can be actuated hydraulically

Info

Publication number: WO2013164072A1
Application number: PCT/EP2013/001181
Authority: WO
Inventors: Daniel Feld
Original assignee: Hydac Technology Gmbh
Priority date: 2012-05-03
Filing date: 2013-04-20
Publication date: 2013-11-07
Also published as: DE102012009670A1

Abstract

The invention relates to a device for saving energy in hydraulically actuated working appliances (1), comprising a supply unit, in particular in the form of a hydraulic pump (33) and a piston accumulator (5) with a piston (9) which can be moved longitudinally in an accumulator housing (7), the piston rod (17) thereof being guided longitudinally in a separating wall (11) of the accumulator housing (7), said wall defining cylinder chambers together with the piston (9). A cylinder chamber is fluidically connected to the working appliances (1) as a pressure actuation chamber (13) for supplying the pressure required for a working step, another cylinder chamber (25) can be connected to the supply unit by means of a pressure control device (29) and an additional cylinder chamber forms a pressure accumulator chamber (21). Said invention is characterized in that a hollow piston rod in the shape of a tube (17) is closed on the end thereof facing the piston (9) and is open on the free end (19) in the cylinder chamber (21) separated by the separating wall (11) of the piston (9).

Description

Device for energy saving

in hydraulically operated equipment

The invention relates to a device for energy saving in hydraulically actuated work equipment, with a supply unit, in particular in the form of a hydraulic pump and a piston accumulator with a longitudinally movable in a storage housing piston whose piston rod is guided longitudinally movable in a partition wall of the storage housing, which together with the Piston cylinder spaces limited, wherein a cylinder space is connected as a pressure-actuated space for the required for a work pressure supply to the working equipment fluid leading, another cylinder space via a pressure control device to the supply unit is connectable and another cylinder chamber forms a pressure storage space.

Energy saving and recovery devices, which have as a piston accumulator a double piston accumulator with a plurality of positively coupled pistons and belonging to a different genus, are known from EP 0 897 480 B1 and EP 1 254 319 B1. During operation of such devices, during movements of the pistons of the piston accumulator forcibly coupled to one another via the coupling part, a higher internal pressure, which decreases in the direction of relaxation, increases as the pistons in the other travel direction increase in magnitude. Lumens move the accumulator chamber. The amount of fluid trapped in the accumulator chamber forms a kind of energy accumulator, comparable to a mechanical spring, and the kinetic energy of the working equipment introduced by the traversing movement into the accumulator space can be retrieved again.

In these known solutions, the piston accumulator designed in the form of a double piston accumulator is permanently connected to the working equipment as the central part of the energy saving and recovery device, so that energy is continuously stored in the piston accumulator and retrieved therefrom as a function of the working movement of the working equipment , The work equipment can be in particular work machines, such as excavators or the like, in which boom to raise and lower, but if necessary, such devices can also be used in other hydraulic systems, such as hydraulic brake systems, in elevators and hydraulic motors or similar.

With a particular advantage, such devices can be used as workload compensation systems in working apparatuses such as excavators or the like, wherein a corresponding internal pressure in the pressure storage space is assigned to a piston or boom position of the hydraulically actuated working equipment, which, when the boom is to be lifted under load, relaxed under usable energy release.

To avoid overcompensation, the system may advantageously be designed so that the pressure of the gas cushion, which generates the compensation force, is less than the load pressure generated by the load force on the double piston. Based on this prior art, the present invention seeks to provide a device of the type considered available, which is characterized by a particularly favorable performance, especially when used for load compensation systems.

According to the invention this object is achieved by a device having the features of claim 1 in its entirety.

According to the characterizing part of claim 1, an essential feature of the invention is that a hollow piston rod is provided in the form of a tube which is closed at its end associated with the piston and at the free end which extends through the partition wall from the piston separated cylinder space is open.

As a result, a piston accumulator is formed, which corresponds to a single piston functionally a double piston accumulator, because the tube together with the piston part surface which is surrounded by the closed end of the tube, in the cylinder space in which the pipe end is located as the second Piston acts. The fact that only one piston has to be performed circumferentially under appropriate fit and seal on the cylinder wall, simplifies the design of the piston accumulator while reducing friction losses.

In a particularly advantageous manner, the volume of the interior of the tube is available as an additional volume for the cylinder chamber associated with the tube end. This cylinder space located at the free end of the tube can be provided as an accumulator space, preferably when using a gaseous pressure medium such as N. 2. In an advantageous manner, despite a compact design and low space required a large volume of gas for the pressure pad to be formed in the pressure accumulator space available , With particular advantage, the pressure storage space can be connected to a pressure supply device, which can have at least one pressure accumulator, for example in the form of an N 2 bottle. Likewise, it may be provided with its gas side connected to the pressure accumulator space hydraulic accumulator.

Additional, nachschaltbare pressure accumulator can be provided.

With particular advantage, the arrangement may be made such that the adjacent to the full-surface piston side of the piston cylinder chamber is provided as a pressure actuating space.

The pressure control device may comprise at least one controllable switching valve, by means of which the supply unit, preferably in the form of the hydraulic pump with the hollow piston rod surrounding the cylinder annulus is connectable, which is located between the partition wall and the piston.

The working equipment can comprise at least one hydraulically actuatable working cylinder, which can be connected to the pressure actuating chamber of the piston accumulator, preferably with its working space adjacent to the full-surface piston side of its working piston.

In particularly advantageous embodiments, the arrangement may be such that the hollow piston rod is guided in the region of the open tube end by means of a guide device on the cylinder wall.

The appropriate guidance of the free end of the tube avoids the risk of vibrations during vibrations, so that the device can be used to particular advantage in mobile machines. The guide device may have fluid passages, so that it has to fulfill only guiding tasks and no sealing fit is required. On the other hand, the arrangement may be such that the guide device forms a seal on the cylinder wall, so that a second, the hollow piston rod surrounding cylinder annulus is formed, both cylinder annuli are selectively connected by means of the switching valve alternately with the supply unit and a tank port. As a result, the second cylinder annulus space for generating an active return movement of the extended working piston can be used.

Alternatively, for the active return movement of the working piston of a working cylinder which is closed on the rod side of its working piston, the rod-side working space of the working cylinder via the switching valve with the hydraulic pump can be connected.

The invention with reference to embodiments shown in the drawings will be described in detail. Show it:

Fig. 1 in principle and not to scale a representation

Schematic representation of an embodiment of the device according to the invention and

FIGS. 2 to 8 of FIG. 1 are corresponding illustrations of further embodiments of the device according to the invention.

The exemplary embodiment of the device according to the invention shown in FIG. 1 in the form of a schematically simplified circuit diagram serves to save and recover energy in the case of hydraulically actuated working devices, of which only one working cylinder is shown in FIG. stel lt and is denoted by 1. The working cylinder 1 is hydraulically operable to produce a working or extending movement of the working piston 3, which takes place against a load or counterforce indicated in FIG. 1 by an arrow I F. It may be the load of a crane jib or the like trade n. The device further comprises egg nen piston accumulator 5, in the housing 7 ei n longitudinally movable piston 9 is arranged. The fitting on the inner wall of the housing 7 guided piston 9 bounded together with a partition wall 1 1, which is arranged approximately centrally in the housing 7 and this separates into two Gehäusetei le, within the housing 7 more Zyl inderräume. Of these, the cylinder space adjoining the vol piston side of the piston 9 is provided as a pressure actuating space 1 3, which for the supply of the working cylinder 1 required for working operations with a pressure fluid via a line 1 5 to the working cylinder 1 connected is.

On the other side of the piston piston 9 is a kind of hollow piston rod bi ldendes tube 1 7, which extends through the partition 1 1 in the distance from the piston 9 Tei l of the housing 7 inside. The tube 1 7 is at this, from the piston 9 remote, free end 1 9 open. The Zyl i nderraum in which this pipe end is 1 9 is provided as with a pressure medium befül age accumulator chamber 21, which is biased at vorl hegenden example with standing under egg nem nem pressure bias gas such as Ni. For the supply of the pressure storage chamber 21 with pressure medium under the pre-charge pressure, a pressure-supply device is provided in the exemplary embodiment of FIG. 1 which has a pressure gas 22 containing pressure gas such as N 2.

As a result, in addition to the additional gas space defined by the inner space of the pipe 1 7, additional compressed gas volumes are available, which can optionally be connected to the pressure storage space 21 by a valve arrangement, not shown in FIG. With its interior space 23 this sets Pipe 1 7 the volume of the accumulator chamber 21 to the closed end of the tube 1 7 on the piston 9 away, ie the pressure prevailing in the pressure accumulator 21 pressure acts on the piston 9 on the piston part surface corresponding to the cross-sectional area of the piston 9 mounted on the pipe 1 7. The remaining on the outside of the tube 1 7 annular surface of the piston 9 delimited together with the partition wall 1 1 surrounding the pipe 1 7 annular space which is provided in the present example as a pump chamber 25 and connected via a line 27 to the pressure control device 29. The pressure control device 29 has a controllable switching valve 31 in the form of a 2/2-way valve, via which the pump chamber 25 is selectively connectable to a supply unit, preferably in the form of a hydraulic pump 33 or tank 35. The pressure storage space 21 is connected to the pressure supply device, which in the present example is provided as a pressure vessel 22 for N 2.

FIG. 1 shows the device in an operating state which corresponds to the center position of the working piston 3 and the piston 9 of the piston accumulator 5. In this case, the preload pressure which prevails in the accumulator chamber 21 compensates for the internal pressure generated by the opposing force F in the working cylinder 1, via the line 15 in the pressure actuation space 13. In a lowering, ie a return movement of the working piston 3, which causes the pressure line 15 in the pressure actuating chamber 13 pressure increase leads to a displacement of the piston 9 in the Fig. Left to a pressure increase in the pressure storage chamber 21, ie to build a reinforced pressure pad that for a subsequent operation, if for an extension movement of the working piston 3, the pump chamber 25 is connected via the switching valve 31 to the hydraulic pump 33, in the sense of energy recovery is available. During the return movement of the working piston 3, ie at a lowering of a relevant load, the pump chamber 25 via the switching valve 31 to the tank 35 is depressurized.

The return movement of the working piston 3 can be passive, i. by displacement of the working piston 3 by means of the acting load force F or other counterforce F of the working tool shaft. Alternatively, as is the case in the embodiment of FIG. 2, an active return movement of the working piston 3 can be effected. For this purpose, the example of FIG. 2 differs from the example of FIG. 1 in that the working cylinder 1 forms a closed, rod-side space 37 on the rod side of the working piston 3. At the same time, the switching valve 31 is formed by a directional valve, which makes it possible to connect the rod-side chamber 37 via a return line 39 to the hydraulic pump 33, while the pump chamber 25 is connected via the switching valve 31 at the same time with tank 35. Incidentally, the example of FIG. 2 does not differ functionally from the example of FIG. 1.

The embodiment of FIG. 3 differs from the example of FIG. 1 only insofar as instead of a single pressure accumulator 22, two pressure accumulators 22 are provided which can be switched on respectively associated switching valves 41 and 43 individually or jointly the pressure accumulator space 21. The pressure accumulators 22 may have the same design and contribute only to increase the total gas volume, or may have different pressure levels to produce different biasing pressures, which can generate different operating characteristics during operation, for example, to adapt to different base loads, such as by a tool change the working equipment can be conditional. The embodiment of FIG. 4 again corresponds to the example of FIG. 2, except that here as a pressure supply device two pressure accumulator 22 are provided, which are connected via switching valves 41 and 43 the pressure accumulator space 21.

The example of FIG. 5 corresponds in function to the example of FIG. 1, except that the tube 1 7 is guided at its open end 19 by means of a guide 45 on the cylinder wall of the housing 7. This guide 45 has fluid passages 47, i. it only has a guiding function without a seal being formed at the pipe end 19. While the tube 17 is thus secured against vibrations during operation, this example also corresponds functionally to the example of FIG. 1.

The example shown in FIG. 6 differs from the example of FIG. 5 only in that in turn the pressure supply device 2 optionally has pressure accumulators 21 which can be connected to the pressure accumulator chamber 21 with associated switching valves 41 and 43.

In contrast to FIGS. 5 and 6, in the exemplary embodiment of FIG. 7, the guide device 45 at the pipe end 19 performs the dual function of guiding and sealing against the cylinder wall of the housing 7. Thus, as in the case of a conventional double-piston accumulator having two accumulator pistons to the cylinder annulus, which forms the pump chamber 25, an additional annular space 49 is formed, which surrounds the hollow piston rod, ie the tube 1 7, and is located between the partition wall 1 1 and guide means 45. This additional annular space 49 can be used as a reversing space to effect an active return movement of the working piston 3 by pressure build-up in the annular space 49. For this purpose, this annulus 49 is connected via a return line 51 by means of the switching valve 31 to the hydraulic pump 33. The example of Fig. 8 corresponds to the example of Fig. 7, except that the pressure supply device again has two pressure accumulators 22, which are connected via switching valves 41 and 43 the pressure accumulator space 21.

Claims

P a n t a n s p r e c h e

Device for energy saving in hydraulically actuated working equipment (1), with a supply unit, in particular in the form of a hydraulic pump (33) and with a piston accumulator (5) with a longitudinally movable in a storage housing (7) piston (9), the piston rod (1 7th ) in a partition wall (1 1) of the storage housing (7) is longitudinally movable, which defines together with the piston (9) cylinder chambers, a Zyl inderraum as a pressure actuating chamber (1 3) for the erforderl for a work Ie pressure supply to the working equipment ( 1) is connected to carry fluid, another cylinder space (25) via a pressure control device (29) is connectable to the supply unit and another cylinder space forms an accumulator chamber (21), characterized in that a hollow piston rod in the form of a tube (1 7) is provided is, at its the piston (9) facing the end closed and at the free end (19) extending in the durc h is the partition wall (1 1) from the piston (9) separate cylinder space (21) is open.

Device according to Claim 1, characterized in that the cylinder space located at the free end (19) of the hollow piston rod is provided as an accumulator chamber.

Apparatus according to claim 1 or 2, characterized in that the pressure storage space (21) can be connected to a pressure supply device.

Device according to one of the preceding claims, characterized in that the pressure supply device has at least one pressure accumulator (22). Device according to one of the preceding claims, characterized in that the cylinder space adjoining the full-surface piston side of the piston (9) is provided as a pressure-actuating space (13).

Device according to one of the preceding claims, characterized in that the pressure control device (29) at least one controllable switching valve (31), by means of which the supply unit (33) with the hollow piston rod (1 7) surrounding the cylinder annulus (25) is connectable, the is located between the partition (1 1) and the piston (9).

Device according to one of the preceding claims, characterized in that the working equipment at least one hydraulically actuable working cylinder (1), preferably with its on the full-surface piston side of a working piston (3) adjacent working space, with the pressure actuating chamber (1 3) of the piston accumulator ( 5) is connectable.

Device according to one of the preceding claims, characterized in that the hollow piston rod (1 7) in the region of the open tube end (19) by means of a guide device (45) is guided on the cylinder wall.

Device according to one of the preceding claims, characterized in that a fluid-permeable guide device (45) is provided.

Device according to one of the preceding claims, characterized in that the guide device (45) forms a seal on the cylinder wall, so that a second, the hollow piston rod (1 7) surrounding the cylinder annulus (49) is formed, and that both cylinder annuli (25, 49) optionally by means of the switching valve (31) alternately with the supply unit (33) and a Tankan- schlus (35) are connectable.

Device according to one of the preceding claims, characterized in that in a working cylinder (1) which is closed on its rod side, the rod-side working space (37) of Arbeitszyl inder (1) via the switching valve (31) with the supply unit (33) connectable is.

Device according to one of the preceding claims, characterized in that the pressure supply device has a plurality of pressure accumulators (22) which can be connected individually or jointly via associated valve devices (41, 43) to the pressure accumulator space (21).