Apparatus for the energy-optimized hydraulic control of at least one double-action working cylinder

Abstract

The invention relates to an apparatus for the energy-optimized hydraulic control of at least one double-action working cylinder of a work machine comprising a hydraulic pressure transducer which is hydraulically connected to a first piston surface of the working cylinder, to a second piston surface of the working cylinder and to at least one pressure accumulator, wherein the pressure transducer is configured such that the hydraulic energy of a high-pressure volume flow conveyed by the first piston surface to the pressure transducer can be stored completely or at least partially by the at least one connected pressure accumulator and such that the cylinder chamber of the second piston surface of the working cylinder can be filled with a low-pressure volume flow by the pressure transducer.

Claims

1. A hydraulic circuit for operating a work machine, comprising a double acting working cylinder (1) comprising a piston rod and head, a hydraulic valve (14) coupled to a base side of the double acting working cylinder (1), a hydraulic valve and connection (12, 13) coupled to the hydraulic valve (14) on a side opposite the working cylinder (1), a pressure transducer (A) coupled (15) to the hydraulic valve and connection (12, 13) and the hydraulic valve (14) on the side opposite the working cylinder (1), said pressure transducer (A) comprising two separate cylinders coupled together through a double-headed piston rod (A3), an accumulator (11) coupled to one of these separate transducer cylinders, a restriction valve (9) coupled to a low pressure outlet (16) from the transducer (A) and, on an opposite side, to a rod side of the double acting cylinder (1), a further hydraulic valve (5) coupled between the restriction valve (9) and the rod side of the double acting cylinder (1), and between the hydraulic valve (14) and the base side of the double acting cylinder (1), and a tank (7) coupled to the further hydraulic valve (5) between the restriction valve (9) and the rod side of the double acting cylinder (1) and, on an opposite side, between the low pressure outlet (16) and the restriction valve (9).

2. The hydraulic circuit of claim 1, wherein the accumulator (11) is coupled to a piston chamber (A2) of one (A1) of the cylinders, said hydraulic valve and connection (12, 13) are coupled (15) to a ring chamber (A4) of the same cylinder (A1), said low pressure outlet (16) is located on a ring chamber (A5) of the other cylinder, and a second tank (10) is coupled to a piston chamber (A6) of the other cylinder.

3. The hydraulic circuit of claim 2, additionally comprising a check valve (4) positioned between the working cylinder (1) and the restriction and hydraulic valves (9, 5), a pre-charging valve (6) positioned between the first tank (7) and the check valve (4) and the restriction and hydraulic valves (9, 5), and a suction valve (8) positioned between the first tank (7) and said restriction valve (9) and said low pressure outlet (16).

4. The hydraulic circuit of claim 1, wherein said hydraulic valve and connection (12, 13) are coupled (15) to a piston chamber (A2) of one (A1) of the cylinders, said low pressure outlet (16) is located on a ring chamber (A4) of the same cylinder (A1), the accumulator (11) is coupled to a piston chamber (A6) of the other cylinder, and a second tank (10) is coupled to a ring chamber (A5) of the other cylinder.

5. The hydraulic circuit of claim 4, additionally comprising a check valve (4) positioned between the working cylinder (1) and the restriction and hydraulic valves (9, 5), a pre-charging valve (6) positioned between the first tank (7) and the check valve (4) and the restriction and hydraulic valves (9, 5), and a suction valve (8) positioned between the first tank (7) and said restriction valve (9) and said low pressure outlet (16).

6. A hydraulic circuit for operating a work machine, comprising a double acting working cylinder (1) comprising a piston rod and head, a hydraulic valve (14) coupled to a base side of the double acting working cylinder (1), a hydraulic valve and connection (12, 13) coupled to the hydraulic valve (14) on a side opposite the working cylinder (1), a pressure transducer (B) coupled (15) to the hydraulic valve and connection (12, 13) and the hydraulic valve (14) on the side opposite the working cylinder (1), said pressure transducer (B) comprising a differential cylinder having a piston chamber (B2), a piston (B3) mounted therein, a ring chamber (B4), and a secondary cylinder comprising a rod chamber (B5), an accumulator (11) coupled to one of these chambers (B2, B5), a restriction valve (9) coupled to a low pressure outlet (16) from the transducer (B) and, on an opposite side, to a rod side of the double acting cylinder (1), a further hydraulic valve (5) coupled between the restriction valve (9) and the rod side of the double acting cylinder (1), and between the hydraulic valve (14) and the base side of the double acting cylinder (1), and a tank (7) coupled to the further hydraulic valve (5) between the restriction valve (9) and the rod side of the double acting cylinder (1) and, on an opposite side, between the low pressure outlet (16) and the restriction valve (9).

7. The hydraulic circuit of claim 6, wherein the accumulator (11) is coupled to the ring chamber (B4) of the differential cylinder, said hydraulic valve and connection (12, 13) are coupled (15) to the piston chamber (B2) of the differential cylinder, and said low pressure outlet (16) is located on the rod chamber (B5) of the secondary cylinder.

8. The hydraulic circuit of claim 7, additionally comprising a check valve (4) positioned between the working cylinder (1) and the restriction and hydraulic valves (9, 5), a pre-charging valve (6) positioned between the tank (7) and the check valve (4) and the restriction and hydraulic valves (9, 5), and a suction valve (8) positioned between the tank (7) and said restriction valve (9) and said low pressure outlet (16).

9. The hydraulic circuit of claim 6, wherein the accumulator (11) is coupled to the rod chamber (B5) of the secondary cylinder, said hydraulic valve and connection (12, 13) are coupled (15) to the piston chamber (B2) of the differential cylinder, and said low pressure outlet (16) is located on the rod chamber (B4) of the differential cylinder.

10. The hydraulic circuit of claim 9, additionally comprising a check valve (4) positioned between the working cylinder (1) and the restriction and hydraulic valves (9, 5), a pre-charging valve (6) positioned between the tank (7) and the check valve (4) and the restriction and hydraulic valves (9, 5), and a suction valve (8) positioned between the tank (7) and said restriction valve (9) and said low pressure outlet (16).

11. A hydraulic circuit for operating a work machine, comprising a double acting working cylinder (1) comprising a piston rod and head, a hydraulic valve (14) coupled to a base side of the double acting working cylinder (1), a hydraulic valve and connection (12, 13) coupled to the hydraulic valve (14) on a side opposite the working cylinder (1), a pressure transducer (C) coupled (15) to the hydraulic valve and connection (12, 13) and the hydraulic valve (14) on the side opposite the working cylinder (1), said pressure transducer (C) comprising a tandem cylinder having an upper ring chamber (C2), a lower ring chamber (C4), a piston rod (C3) disposed in the upper and lower ring chambers (C2, C4), and a rod chamber (C5), an accumulator (11) coupled to one of these chambers (C4, C5), a restriction valve (9) coupled to a low pressure outlet (16) from the transducer (C) and, on an opposite side, to a rod side of the double acting cylinder (1), a further hydraulic valve (5) coupled between the restriction valve (9) and the rod side of the double acting cylinder (1), and between the hydraulic valve (14) and the base side of the double acting cylinder (1), and a tank (7) coupled to the further hydraulic valve (5) between the restriction valve (9) and the rod side of the double acting cylinder (1) and, on an opposite side, between the low pressure outlet (16) and the restriction valve (9).

12. The hydraulic circuit of claim 11, wherein the accumulator (11) is coupled to the lower ring chamber (C4) of the tandem cylinder, said hydraulic valve and connection (12, 13) are coupled (15) to the upper ring chamber (C2) of the tandem cylinder, and said low pressure outlet (16) is located on the rod chamber (C5).

13. The hydraulic circuit of claim 12, additionally comprising a check valve (4) positioned between the working cylinder (1) and the restriction and hydraulic valves (9, 5), a pre-charging valve (6) positioned between the tank (7) and the check valve (4) and the restriction and hydraulic valves (9, 5), and a suction valve (8) positioned between the tank (7) and said restriction valve (9) and said low pressure outlet (16).

14. The hydraulic circuit of claim 11, wherein the accumulator (11) is coupled to the rod chamber (C5), said hydraulic valve and connection (12, 13) are coupled (15) to the upper ring chamber (C2) of the tandem cylinder, and said low pressure outlet (16) is located on the lower ring chamber (C4) of the tandem cylinder.

15. The hydraulic circuit of claim 14, additionally comprising a check valve (4) positioned between the working cylinder (1) and the restriction and hydraulic valves (9, 5), a pre-charging valve (6) positioned between the tank (7) and the check valve (4) and the restriction and hydraulic valves (9, 5), and a suction valve (8) positioned between the tank (7) and said restriction valve (9) and said low pressure outlet (16).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages and properties of the invention will be explained in the following with reference to a plurality of embodiments shown in the drawings.

(2) There are shown:

(3) FIG. 1: a first embodiment of the apparatus in accordance with the invention;

(4) FIG. 2: a second embodiment of the apparatus in accordance with the invention;

(5) FIG. 3: a third embodiment of the apparatus in accordance with the invention;

(6) FIG. 4: a fourth embodiment of the apparatus in accordance with the invention;

(7) FIG. 5: a fifth embodiment of the apparatus in accordance with the invention; and

(8) FIG. 6: a sixth embodiment of the apparatus in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(9) An overview of the hydraulic circuit, which represents the invention described here, is shown in FIGS. 1 to 6. The circuit having the working cylinder 1 is a component of a work machine, for example of a crane or of a construction machine. The working cylinder or cylinders 1 serve as lifting cylinder(s) for carrying out a lifting movement of the boom system of the machine. When lowering the boom system, the load of the boom acts on the working cylinder 1 and allows an unpressurized retracting movement of the piston rod into the cylinder.

(10) The circuit in accordance with the invention is characterized in that, when the working cylinder or cylinders 1 are retracted under a pressing load, the existing potential energy can be stored with the help of a hydraulic store 11 and a pressure transducer A, B, C. In addition, an energy-efficient refilling of the rod side of the working cylinder or cylinders 1 is made possible by the interconnections shown. The invention is additionally characterized by a parallel integration into a work machine, such as a crane or a construction machine, which also allows a problem-free function of all consumers on a failure of the storage apparatus 11.

(11) The hydraulic transducer A, B, C in conjunction with the hydraulic accumulator 11 ensures that oil volume of the base side of the working cylinder or cylinders 1 can be taken up and that the potential energy contained therein can be stored with the help of the hydraulic accumulator 11. At the same time, the hydraulic pressure transducer A, B, C implements the filling of the rod sides of the working cylinder(s) 1 in that it displaces the oil volume necessary for this purpose. This oil displacement takes place at a low-pressure level since the base-side high-pressure level is compensated by the hydraulic accumulator 11. The speed of the lowering process can be set by a restriction valve 9 between the hydraulic pressure transducer A, B, C and the rod side of the working cylinders 1. The filling of the rod sides of the working cylinders 1 is characterized as energy-efficient since the restriction point 9 only has to generate comparatively small pressure losses to set the lowering speed.

(12) The described circuit can be operated with three different pressure transducers A, B and C in two respectively different interconnections. They only differ by the arrangement of the hydraulic accumulator 11 and by the design of the pressure transducer A, B, C. The following applies to all interconnections:

(13) If the storage process is to be started, a force must be applied to the working cylinder 1 which results in the retraction of the working cylinder 1. A pressure is hereby built up on the base side of the working cylinder 1 which defines the potentially available energy. This potential energy should be taken up by a hydraulic accumulator 11. A connection between the base side and the connection 15 of the pressure transducer A, B or C is provided by the hydraulic valve 14 designed as a switch valve or as a proportional valve. A pressure is adopted at the outlet 16 on the basis of the equilibrium of forces within the pressure transducer A, B or C. No retracting movement of the working cylinder 1 can take place up to the actuation of the hydraulic valve 9. The escape of an oil volume from the pressure transducer A, B or C is made possible by a proportional control of the hydraulic valve 9 and the speed of the retracting movement of the working cylinder 1 is simultaneously determined. It made possible by the hydraulic valve 9 for this volume flow to move via the check valve 4 into the rod-side chamber of the working cylinder 1. An exiting volume flow is generated at the outlet 16 on the take-up of volume flow at the connection 15 due to the configuration of the pressure transducer A, B or C. The excess volume flow which is not needed for filling the rod-side chamber of the working cylinder 1 is led by the precharging valve 6 to the tank 7 with an adjustable precharging pressure at the precharging valve 6.

(14) If the storage process is stopped, the normal control can be initiated for retracting the working cylinder 1. The hydraulic valves 9 and 14 are closed for this purpose. The volume flow from the base-side chamber of the working cylinder 1 is led via the check valve 4 into the rod-side chamber of the working cylinder 1 by a proportional control of the hydraulic valve 5. The excess oil quantity from the base side of the working cylinder 1 is led into the tank 7 via the precharging valve 6 with an adjustable precharging pressure. The normal control of the working cylinder 1 for lifting and lowering without a storage process takes place via the connections 2 and 3. An outflow of the supplied volume flow at connection 2 to the tank is prevented by the check valve 4.

(15) The hydraulic valves 9 and 14 are kept closed for reusing the hydraulic energy in the hydraulic accumulator 11. Pressurized volume flow which escapes from the connection 15 of the pressure transducer can be taken off at the connection 12 by a switching or proportional actuation of the hydraulic valve 13. A volume flow shortage arises at the low-pressure connection 16 by removal of volume flow from the pressure transducer A, B or C at the connection 15. The short volume flow is supplied via the suction valve 8.

(16) All kinds of hydraulic accumulators can be used as the hydraulic accumulator 11. Embodiments as gas accumulators, piston accumulators, membrane accumulators or spring accumulators are conceivable. The direct integration of the accumulator 11 in the pressure transducers A, B, C is furthermore possible. The invention is not restricted to one kind or one type of the energy storage medium. Nitrogen or nitrogen mixtures are typically used in gas accumulators and piston accumulators. In addition, a use of a combination of different pressure transducers and also a use of different accumulators in different combinations is possible. The valves shown can be used as single 2/2 way valves or also as a combination on a valve rod. In this respect, a proportional or switching control is likewise possible.

(17) In accordance with the embodiment of FIG. 1, the pressure transducer A comprises two differential cylinders which are coupled to one another via their piston rods. The primary cylinder has the piston A3, the piston chamber A2 and the ring chamber A4. The secondary cylinder comprises the piston chamber A6 and the ring chamber A5. On actuation of the hydraulic valve 14, a connection is created between the base side of the working cylinder 1 and of the upper ring chamber A4 of the pressure transducer A1 via the connection 15 and the base-side pressure of the working cylinder 1 is applied to the ring surface of the piston A3. The upper piston chamber A2 of the pressure transducer A is connected to a hydraulic accumulator 11. The lower piston chamber A6 of the pressure transducer A is connected to the tank 10 or to the environment.

(18) The lower ring chamber A5 of the pressure transducer A1 is first closed by a hydraulic valve 9 via the low-pressure outlet 16. A pressure is adopted in the lower ring chamber A5 on the basis of the equilibrium of forces at the piston A3 of the pressure transducer A. The pressure adopted is reduced in the lower ring chamber A5 in contrast to the base-side pressure of the working cylinder 1 by the oppositely acting forces of the pressures in the upper piston chamber A2 and the upper ring chamber A4. No retracting movement of the working cylinder 1 can take place up to the actuation of the hydraulic valve 9 at the outlet 16. An escape of the oil volume out of the lower ring chamber A4 via the outlet 16 is made possible by a proportional control of the hydraulic valve 9. This volume flow moves through the hydraulic valve 9 via the check valve 4 into the rod-side chamber of the working cylinder 1. A proportional volume flow is displaced from the lower ring chamber A5 on the take-up of volume flow into the upper ring chamber A2 by the configuration of the piston A3. The excess volume flow which is not needed for filling the rod-side chamber of the working cylinder 1 is led by the precharging valve 6 to the tank 7 with an adjustable precharging pressure at the precharging valve 6.

(19) The embodiment of FIG. 2 likewise makes use of the pressure transducer A in accordance with FIG. 1, but the interconnection to the working cylinder 1 and to the store 11 takes place in a different manner from this. On actuation of the hydraulic valve 14, a connection is created between the base side of the working cylinder 1 and of the upper piston chamber A2 of the pressure transducer A via the connection 15 and the base-side pressure of the working cylinder 1 is applied to the upper piston surface of the piston A3. The lower piston chamber A6 of the pressure transducer A is connected to a hydraulic accumulator 11. The lower ring chamber A5 of the pressure transducer A is connected to the tank 10 or to the environment. The upper ring chamber A4 of the pressure transducer A is first closed by a hydraulic valve 9 via the outlet 16. A pressure is adopted in the upper ring chamber A4 on the basis of the equilibrium of forces at the piston A3 of the pressure transducer A. The pressure adopted is reduced in the upper ring chamber A4 in contrast to the base-side pressure of the working cylinder 1 by the oppositely acting forces of the pressures in the upper piston chamber A2 and the lower ring chamber A5. No retracting movement of the working cylinder 1 can take place up to the actuation of the hydraulic valve 9 at connection 16. An escape of the oil volume out of the upper ring chamber A4 via connection 16 is made possible by a proportional control of the hydraulic valve 9. This volume flow moves through the hydraulic valve 9 via the check valve 4 into the rod-side chamber of the cylinder 1. A proportional volume flow is displaced from the upper ring chamber A4 on the take-up of volume flow into the upper ring chamber A2 by the configuration of the piston A3. The excess volume flow which is not needed for filling the rod-side chamber of the working cylinder 1 is led by the precharging valve 6 to the tank 7 with an adjustable precharging pressure at the precharging valve 6.

(20) FIG. 3 shows an embodiment with another pressure transducer B. It comprises a differential cylinder with the piston chamber B2, the piston B3 and the ring chamber B4. The secondary cylinder is a plunger cylinder having the rod chamber B5. On actuation of the hydraulic valve 14, a connection is created between the base side of the working cylinder 1 and the piston chamber B2 of the pressure transducer B via the connection 15 and the base-side pressure of the working cylinder 1 is applied to the piston surface of the piston B3. The ring chamber B4 of the pressure transducer B is connected to a hydraulic accumulator 11. The rod chamber B5 of the pressure transducer B is first connected via connection 16 to a hydraulic valve 9. A pressure is adopted in the rod chamber B5 on the basis of the equilibrium of forces at the piston B3 of the pressure transducer B. The pressure adopted is reduced in the rod chamber B5 in contrast to the base-side pressure of the working cylinder 1 by the oppositely acting forces of the pressures in the piston chamber B2 and the ring chamber B4. No retracting movement of the working cylinder 1 can take place up to the actuation of the hydraulic valve 9 at the connection 16. An escape of the oil volume out of the rod chamber B5 via the connection 16 is made possible by a proportional control of the hydraulic valve 9. This volume flow moves through the hydraulic valve 9 via the check valve 4 into the rod-side chamber of the working cylinder 1. A proportional volume flow is displaced from the rod chamber B5 on the take-up of volume flow into the piston chamber B2 by the configuration of the piston B3. The excess volume flow which is not needed for filling the rod-side chamber of the working cylinder 1 is led by the precharging valve 6 to the tank 7 with an adjustable precharging pressure at the precharging valve 6.

(21) The embodiment of FIG. 4 likewise uses the pressure transducer B in accordance with FIG. 3, but uses a modified interconnection. On actuation of the hydraulic valve 14, a connection is created between the base side of the working cylinder 1 and the piston chamber B2 of the pressure transducer B via the connection 15 and the base-side pressure of the working cylinder 1 is applied to the piston surface of the piston B3. The rod chamber B5 of the pressure transducer B is connected to a hydraulic accumulator 11. The ring chamber B4 of the pressure transducer B is first connected via connection 16 to a hydraulic valve 9. A pressure is adopted in the ring chamber B4 on the basis of the equilibrium of forces at the piston B3 of the pressure transducer B. The pressure adopted is reduced in the ring chamber B4 in contrast to the base-side pressure of the working cylinder 1 by the oppositely acting forces of the pressures in the piston chamber B2 and the rod chamber B5. No retracting movement of the working cylinder 1 can take place up to the actuation of the hydraulic valve 9 at the connection 16. An escape of the oil volume out of the ring chamber B4 via connection 16 is made possible by a proportional control of the hydraulic valve 9. This volume flow moves through the hydraulic valve 9 via the check valve 4 into the rod-side chamber of the working cylinder 1. A proportional volume flow is displaced from the ring chamber B4 on the take-up of volume flow into the piston chamber B2 by the configuration of the piston B3. The excess volume flow which is not needed for filling the rod-side chamber of the working cylinder 1 is led by the precharging valve 6 to the tank 7 with an adjustable precharging pressure at the precharging valve 6.

(22) The embodiment of FIG. 5 uses the pressure transducer C which comprises a tandem cylinder with the upper ring chamber C2, the piston C3 and the lower ring chamber C4. The tandem cylinder is coupled via its piston rod to the plunger cylinder which comprises the rod chamber C5. On actuation of the hydraulic valve 14, a connection is created between the base side of the working cylinder 1 and the upper ring chamber C2 of the pressure transducer C via connection 15 and the base-side pressure of the working cylinder 1 is applied to the upper ring surface C2 of the piston C3. The lower ring chamber C4 of the pressure transducer C is connected to a hydraulic accumulator 11. The rod chamber C5 of the pressure transducer C is first connected via connection 16 to a hydraulic valve 9. A pressure is adopted in the rod chamber C5 on the basis of the equilibrium of forces at the piston C3 of the pressure transducer C. The pressure adopted is reduced in the rod chamber C5 in contrast to the base-side pressure of the working cylinder 1 by the oppositely acting forces of the pressures in the upper ring chamber C2 and the lower ring chamber C4. No retracting movement of the working cylinder 1 can take place up to the actuation of the hydraulic valve 9 at connection 16. An escape of the oil volume out of the rod chamber C5 via the connection 16 is made possible by a proportional control of the hydraulic valve 9. This volume flow moves through the hydraulic valve 9 via the check valve 4 into the rod-side chamber of the working cylinder 1. A proportional volume flow is displaced from the rod chamber C5 on the take-up of volume flow into the upper ring chamber C2 by the configuration of the piston C3. The excess volume flow which is not needed for filling the rod-side chamber of the working cylinder 1 is led by the precharging valve 6 to the tank 7 with an adjustable precharging pressure at the precharging valve 6.

(23) The last embodiment of FIG. 6, in contrast to the embodiment in accordance with FIG. 5, only provides a modified interconnection of the pressure transducer C. On actuation of the hydraulic valve 14, a connection is created between the base side of the working cylinder 1 and the upper ring chamber C2 of the pressure transducer C via connection 15 and the base-side pressure of the working cylinder 1 is applied to the upper ring surface C2 of the piston C3. The rod chamber C5 of the pressure transducer C is connected to a hydraulic accumulator 11. The lower rod chamber C4 of the pressure transducer C1 is first connected via connection 16 to a hydraulic valve 9. A pressure is adopted in the lower ring chamber C4 on the basis of the equilibrium of forces at the piston C3 of the pressure transducer C1. The pressure adopted is reduced in the lower ring chamber C4 in contrast to the base-side pressure of the working cylinder 1 by the oppositely acting forces of the pressures in the upper ring chamber C2 and the rod chamber C5. No retracting movement of the working cylinder 1 can take place up to the actuation of the hydraulic valve 9 at the connection 16. An escape of the oil volume out of the lower ring chamber C4 via connection 16 is made possible by a proportional control of the hydraulic valve 9. This volume flow moves through the hydraulic valve 9 via the check valve 4 into the rod-side chamber of the working cylinder 1. A proportional volume flow is displaced from the lower ring chamber C4 on the take-up of volume flow into the upper ring chamber C2 by the configuration of the piston C3. The excess volume flow which is not needed for filling the rod-side chamber of the working cylinder 1 is led by the precharging valve 6 to the tank 7 with an adjustable precharging pressure at the precharging valve 6.

(24) The invention is further characterized in that the system for storing the hydraulic energy is designed such that the system is not necessary for the standard operation of the machine. The machine can be operated further as normal on a failure of the storage system.