WORK DEVICE HAVING A HYDRAULIC DRIVE FOR CIVIL ENGINEERING WORK

Abstract

A work device having a hydraulic drive for civil engineering work, in particular a drilling device or vibration pile-driving device, includes a hydraulic motor that is operated by way of a fluid of a hydraulic circuit, which circuit is supplied by way of a hydraulic pump, which pump is driven by an internal combustion engine, wherein at least one heat transfer unit for transfer of thermal energy of a fluid stream of the internal combustion engine to the fluid of the hydraulic circuit is provided. A method temporarily heats the hydraulic fluid of the hydraulic circuit of such a work device.

Claims

1. A hydraulically-driven work device comprising (a) a hydraulic motor; (b) a hydraulic circuit comprising a fluid operating the hydraulic motor; (c) a hydraulic pump supplying the hydraulic circuit; (d) an internal combustion engine driving the hydraulic pump; and (e) at least one heat transfer unit for transfer of thermal energy of a fluid stream of the internal combustion engine to the fluid of the hydraulic circuit.

2. The work device according to claim 1, wherein the hydraulic circuit and a cooling circuit of the internal combustion engine are thermally connected by way of the at least one heat transfer unit.

3. The work device according to claim 2, wherein the at least one heat transfer unit is set up for combined transfer of heat and material, wherein the fluid of the hydraulic circuit functions as a coolant, and wherein the heat transfer unit comprises a coupling and uncoupling device that couples and uncouples the hydraulic circuit and the cooling circuit.

4. The work device according to claim 3, wherein the hydraulic circuit and the cooling circuit are connected by way of a hydraulic fluid tank disposed in the hydraulic circuit.

5. The work device according to claim 2, wherein the at least one heat transfer unit comprises a heat exchanger that is disposed ahead of a cooler in the cooling circuit of the internal combustion engine, wherein at least one of the cooling circuit and the hydraulic circuit has a bypass line that circumvents the heat exchanger, wherein a valve is disposed in the bypass line and is controlled as a function of at least one of a hydraulic fluid stream temperature of the hydraulic circuit and a coolant stream temperature of a coolant stream of the cooling circuit.

6. The work device according to claim 2, further comprising a control and regulation module and a temperature sensor in the hydraulic circuit, wherein the at least one heat transfer unit is connected with the hydraulic circuit or the cooling circuit by way of a valve, wherein the valve is controlled by way of the control and regulation module, wherein the temperature sensor disposed in the hydraulic circuit is connected with the control and regulation module.

7. The work device according to claim 1, wherein the hydraulic circuit and an exhaust gas stream of the internal combustion engine are thermally connected by way of the at least one heat transfer unit.

8. The work device according to claim 7, wherein the at least one heat transfer unit comprises at least one heat exchanger.

9. The work device according to claim 7, wherein an exhaust gas line is disposed on the internal combustion engine and provided with a branch that is connected with the at least one heat transfer unit, wherein the exhaust gas line is provided with a throttle system for temporarily closing the exhaust gas line.

10. The work device according to claim 7, wherein the exhaust gas stream is thermally connected with the hydraulic circuit by way of a heat transfer circuit having a heat carrier fluid, wherein the heat transfer circuit is operated by way of the hydraulic pump.

11. The work device according to claim 10, further comprising a control and regulation module for controlling the hydraulic pump and a temperature sensor disposed in the hydraulic circuit and connected with the control and regulation module.

12. The work device according to claim 10, wherein the heat carrier fluid is a synthetic ester, a salt melt or a liquid metal.

13. The work device according to claim 1, wherein the internal combustion engine has a charger, and the charger has a compressed charging air stream thermally connected with the hydraulic circuit by way of the at least one heat transfer unit.

14. The work device according to claim 13, wherein the at least one heat transfer unit is disposed in a charging air line behind the charger.

15. A method for temporary heating of hydraulic fluid of a hydraulic circuit of a work device having a hydraulic drive for civil engineering work comprising: (a) supplying the hydraulic circuit by way of a hydraulic pump driven by an internal combustion engine having a coolant circuit; (b) passing the hydraulic fluid through a heat transfer unit for a defined period of time; and (c) supplying a fluid stream of the internal combustion engine to the heat transfer unit for transfer of thermal energy.

16. The method according to claim 15, wherein the heat transfer unit is connected with the hydraulic circuit by way of a line, and wherein a multi-way valve is disposed in the line.

17. The method according to claim 15, wherein the hydraulic circuit comprises a fluid tank used as a combined material and heat transfer unit, wherein the hydraulic fluid is simultaneously used as a coolant, and wherein the hydraulic circuit is connected with the cooling circuit of the internal combustion engine for a defined period of time.

18. The method according to claim 17, wherein the hydraulic fluid is a synthetic ester.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other objects and features of the invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention.

[0027] In the drawings,

[0028] FIG. 1 shows a schematic representation of the hydraulic group of a work device with coupling of the hydraulic circuit to the cooling circuit of the internal combustion engine by way of a heat exchanger;

[0029] FIG. 2 shows a representation of the hydraulic group of a work device with coupling of the hydraulic circuit to the cooling circuit of the internal combustion engine by way of a heat exchanger in a further embodiment;

[0030] FIG. 3 shows a representation of the hydraulic group of a work device with connection of the hydraulic circuit with the cooling circuit of the internal combustion engine;

[0031] FIG. 4 shows a representation of the hydraulic group of a work device with connection of the hydraulic circuit with the cooling circuit of the internal combustion engine in a further embodiment;

[0032] FIG. 5 shows a schematic representation of a hydraulic group of a work device with coupling of the hydraulic circuit to the exhaust gas stream of the internal combustion engine by way of a heat exchanger circuit; and

[0033] FIG. 6 shows a representation of the hydraulic group of a work device with coupling of the hydraulic circuit not only to the cooling circuit of the internal combustion engine by way of a heat exchanger but also to the exhaust gas stream of the internal combustion engine by way of a heat exchanger circuit.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0034] In FIG. 1, the hydraulic group of a work device having a hydraulic drive for civil engineering work, for example of a drilling device or vibration pile-driving device, is shown schematically. It comprises a hydraulic pump 1, which is disposed in the line 21 between a hydraulic oil tank 2 and a control block 3 and driven by an internal combustion engine 7. The control block 3 is connected with a hydraulic motor 4, the hydraulic oil inflow of which it controls. The control block 3 is connected with the hydraulic oil tank 2 by way of three lines 31, 32, 33 on the return side. The first line 31 is passed by way of a heat exchanger 6 as a coupling line, by way of a 2/2-way valve 61. The second line 32 is passed by way of a cooler 5 by way of a further 2/2-way valve 51. In the third line 33, a sequence valve 22 is provided as a failure valve, which valve can also be used as a free line to the tank in order to minimize pressure losses.

[0035] Usually, pressure-limiting valves, which can also be integrated into the valves in the form of a pressure stage, are provided in addition to the 2/2-way valves 51, 61 as well as the failure valve 22. In this regard, these pressure-limiting valves are biased in such a manner that significant ram pressures of 5.5 bar and more are guaranteed. In this way, a significant energy demand on the order of up to 12 kW is caused. These ram pressures are kept available in order to prevent cavitation when the work device, which can be a vibrator with rotating imbalance masses, for example, is stopped. It was found that this significant energy demand can be significantly reduced in that the aforementioned valves are structured as controllable proportional valves. Because the significant ram pressures are required only in certain states, the proportional valves can be set at significantly lower ram pressures in normal operation. Depending on events, for example when the work device is shut off, the proportional valves can then be adjusted by way of a controller connected with them, in such a manner that a high ram pressure is formedif necessary even higher than the aforementioned 5.5 bar.

[0036] The line 31, on the one hand, and the cooling circuit 71 of the internal combustion engine 7, on the other hand, are passed by way of the heat exchanger 6. In this regard, the heat exchanger 6 is connected behind the cooler 72 in the cooling circuit. The temperature in the line from the cooler 72, which cools the coolant of the internal combustion engine 7, to the internal combustion engine 7 amounts to less than 90 C. in most engines. The hydraulic oil can be exposed to this temperature for a longer time. If hydraulic oil remains in the heat exchanger 6, which reaches this temperature, the hydraulic oil is not damaged. The waste heat of the internal combustion engine 7, which is absorbed by the coolant, however, will not be utilized maximally in this case, because a large part of the heat energy has already been given off to the surroundings in the prior cooler 72.

[0037] A better degree of effectiveness is achieved if the heat exchanger 6 is connected with the line from the internal combustion engine 7 to the cooler 72 (as shown in FIG. 2). In this regard, however, it should be noted that the coolant temperature is possibly too high here to allow standing hydraulic oil, which is not constantly exchanged, to remain in the heat exchanger 6.

[0038] In this case, the heat exchanger 6 preferably should be separated from the supply of the engine coolant during the time when the first line 31 is closed by way of the 2/2-way valve 61, in other words when the hydraulic oil is not passed by way of the first line 31, in order to interrupt the supply of heat. For this purpose, a bypass line that circumvents the heat exchanger 6 and can be coupled in by way of a provided valve, for example, could be provided in the cooling circuit 71 of the internal combustion engine 7.

[0039] In the exemplary embodiment, a temperature sensor 81 is disposed in the line 21 between the pump 1 and the hydraulic tank 2, which sensor is connected with a control and regulation device 8. The control and regulation device 8 is connected with the 2/2-way valves 51, 61 by way of control lines 82, and set up in such a manner that in the event that the temperature reported by the temperature sensor 81 is lower than a limit temperature stored in the memory of the control and regulation device 8, the 2/2-way valve 61 is opened and the 2/2-way valve 51 is closed. In this position, the hydraulic oil is passed by way of the heat exchanger 6 by the control block 3, and thereby it is heated. After a target temperature stored in the memory of the control and regulation device 8, the 2/2-way valve 61 is closed and the 2/2-way valve 51 is opened, and afterward, the hydraulic oil is passed to the hydraulic oil tank 2 by way of the cooler 5 by the control block 3.

[0040] In the exemplary embodiment according to FIG. 3, the heat transfer unit is set up for combined material and heat transfer. An essential component of the heat transfer unit is the hydraulic oil tank 2 that is present here. In this regard, an identical fluid is used for the hydraulic circuit of the hydraulic motor 4 and as a coolant for the cooling circuit 71 of the internal combustion engine 7. The hydraulic oil tank 2 of the hydraulic circuit is directly connected with the cooling circuit 71 of the internal combustion engine 7 here, by way of an interposed 4/2-way valve 75. The 4/2-way valve 75, just like the 2/2-way valve 51, is connected with the control and regulation device 8 by way of control lines 82, and can be controlled by this device.

[0041] If the 4/2-way valve 75 is set by the control and regulation device 8 in such a manner that the incoming and return lines of the cooling circuit 71 are set to be open, the hydraulic oil is conveyed directly out of the hydraulic oil tank 2 into the cooling circuit 71 of the internal combustion engine 7 by way of the coolant pumpnot shownof the internal combustion engine 7, and thereby it is heated directly, without the involvement of a heat exchanger, by the waste heat of the internal combustion engine 7, before it is passed back into the hydraulic oil tank 2.

[0042] In the exemplary embodiment according to FIG. 4, the cooler 72 is disposed in a bypass line 73, which is connected with the cooling circuit 71 by way of a 3/2-way valve 76 on the supply side. In this way, the cooler 72 can be uncoupled during times in which it is not required. In the exemplary embodiment, the 3/2-way valve 76 is also connected with the control and regulation device 8 by way of control lines 82, and can be controlled by this device.

[0043] In the exemplary embodiment according to FIG. 5, the heat exchanger 6 is incorporated into a heat transfer circuit 62. The heat transfer circuit 62 comprises a pump 63, by way of which a heat transfer medium is circulated between this heat exchanger 6 and a second heat exchanger 64 that is provided. The second heat exchanger 64 is connected with the exhaust gas line 74 of the internal combustion engine 7, so that the exhaust gas stream of the internal combustion engine 7 can flow through it.

[0044] Because very high temperatures can prevail in the region of the exhaust gas line 74, an ester, as a temperature-resistant medium, is interposed as a heat transfer medium. Salt melts or, theoretically, also liquid metals can also be used as further temperature-resistant heat carrier fluids. The second heat exchanger 64, directly disposed at the exhaust gas line 74 of the internal combustion engine 7, transfers the heat to the intermediate medium, by way of which the heat is in turn transferred to the hydraulic oil by way of the first heat exchanger 6. To interrupt the heat supply to the hydraulic oil, the pump 63 can simply be shut off. For this purpose, it is practical to also connect the pump 63 with the control and regulation device 8, which in this case must be set up in such a manner that if the 2/2-way valve 61 is interrupted, the pump 63 is simultaneously shut off or that in the pass-through position of the 2/2-way valve 61, the pump 63 is activated.

[0045] Alternatively, the second heat exchanger 64 can also be disposed on a charger of an internal combustion engine 7, preceding the charging air cooler, in order to utilize the heat of the charging air stream, which also has a very high temperature, for heating the hydraulic oil. Of course, it is also possible to provide multiple heat exchangers, in order to utilize the different waste heat sources of the internal combustion engine for heating the hydraulic oil. For example, a third heat exchanger, by way of which the charging air stream is conducted, can also be provided in the heat transfer circuit 62.

[0046] The possibility also exists of branching off the exhaust gas system, for example after a catalytic converter that is present, in order to utilize the exhaust gas heat, and conducting one train to the exhaust pipe unchanged, and connecting the other train to the heat exchanger 6, in order to supply the heat directly to the hydraulic fluid by way of this heat exchanger 6. For this purpose, only one heat exchanger 6 is required, because only part of the exhaust gas stream is used. The additional heat transfer circuit described above is not necessary. To interrupt the heat supply to the hydraulic oil, the exhaust gas train between the branch and the heat exchanger 6, which ends in the heat exchanger, can be closed by means of a flap or a corresponding slide. This solution has the advantage that the counter-pressure that builds up in the exhaust gas system due to the exhaust gas stream does not increase.

[0047] In the exemplary embodiment according to FIG. 6, two heat exchangers 6, 6 are provided in the first line 31, one behind the other. The cooling circuit 71 of the internal combustion engine 7 is passed by way of the heat exchanger 6. In this regard, the heat exchanger 6 is connected with the line from the internal combustion engine 7 to the cooler 72, analogous to the exemplary embodiment according to FIG. 2. Furthermore, the waste heat of the exhaust gas stream of the internal combustion engine 7 is additionally utilized. For this purpose, the heat exchanger 6 is incorporated into a heat transfer circuit 62, analogous to the exemplary embodiment according to FIG. 6. Here, too, the heat transfer circuit 62 comprises a pump 63, by way of which a heat transfer medium is circulated between this heat exchanger 6 and a second heat exchanger 64 that is provided. The second heat exchanger 64 is connected with the exhaust gas line 74 of the internal combustion engine 7, so that the exhaust gas stream of the internal combustion engine 7 can flow through it. Alternatively, here, too, the possibility described above exists for utilizing the exhaust gas heat of the exhaust gas system, for example of branching after a catalytic converter that is present, and conducting one train to the exhaust pipe unchanged, and connecting the other train directly to the heat exchanger 6, in order to conduct the heat directly to the hydraulic fluid by way of this heat exchanger 6, without the involvement of a heat transfer circuit being required.

[0048] Although only a few embodiments of the present invention have been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.