HK1128748B - Hydraulic drive system with energy recuperation - Google Patents

Description

The present invention relates to a hydraulic drive system for the propulsion of a device, with a drive unit capable of driving the device via a primary hydraulic circuit from a first and second hydraulic displacement machine, and with a third hydraulic displacement machine which is connected or connected to the device for the transfer of mechanical energy, and a high pressure storage device which is connected or connected hydraulically to the third displacement machine. In particular, the present invention relates to a hydraulic drive system used in a crane, in particular the propulsion of a wind turbine.

Such hydraulic drive systems usually have a primary drive unit, such as a combustion engine or an electric motor, which drives one or more hydraulic pumps to provide hydraulic energy to drive the device. To increase the performance of such systems, it is first possible to dimension the drive unit to provide more hydraulic energy. However, the size of the primary drive unit also increases the cost, installation space and energy consumption of the system.

For this reason, hydraulic energy storage systems are increasingly used, e.g. they are charged during braking phases and supply the hydraulic energy stored in them to the drive system during acceleration phases. Thus, the drive unit itself can be reduced in size, as it is supported by the high pressure storage at peak loads. However, in known hydraulic drive systems with such a high pressure storage, satisfactory efficiency for energy storage or energy release cannot be achieved. In addition, the control is often complicated.

The present invention is therefore intended to provide a hydraulic drive system which allows efficient energy storage and easy control.

According to the invention, this task is accomplished by a hydraulic drive system to drive a device as described in claim 1. Such a hydraulic drive system includes a drive unit that can drive the device via a primary hydraulic circuit from a first and second hydraulic displacement machine, and a third hydraulic displacement machine that is connected or connected to the device for the transmission of mechanical energy, and a high pressure storage device that is hydraulically connected or connected to the third displacement machine.

Since the high-pressure storage device can be charged by a hydraulic displacement machine connected or connectable to the drive unit, the high-pressure storage device can be charged at an excellent efficiency in phases where the drive power provided by the drive unit is not or not fully required to drive the device, as the mechanical energy supplied by the drive unit is directly converted into hydraulic energy by the hydraulic displacement machine.

In addition, the arrangement of the invention allows the high-pressure storage to be charged by the drive unit without moving the device, whereas in known systems the high-pressure storage can only be charged if the device is also moved. This results in a significantly improved flexibility in the storage management of the hydraulic drive system of the invention, since the high-pressure storage is also stored in phases in which the device is stationary and thus neither the second nor the third hydraulic displacement machine is moved, the high-pressure storage is charged by a hydraulic displacement machine which is connected to the drive unit for the transfer of mechanical energy or is connected to the recharging unit. The storage of energy can also be optimized by means of a direct mechanical power supply, which is also achieved by means of a hydraulic power management unit.

In particular, the design of the invention makes it possible to operate the drive unit, e.g. a diesel engine, at an optimal operating point at all times and to store the energy not required in the primary hydraulic circuit in the high-pressure storage. During peak loads this energy can then be returned to the drive system, so that the overall system has a high output power and with a relatively small drive unit.

Furthermore, the invention allows the first hydraulic compressor to operate as a hydraulic pump and the second hydraulic compressor to operate as a hydraulic motor, so that the first hydraulic compressor drives the second hydraulic compressor and forms a primary hydraulic circuit. This makes it possible to control the system according to the invention with particular ease, whereby the volume current flowing through the primary hydraulic circuit from the first hydraulic displacement machine and the second hydraulic displacement machine and, if necessary, the setting of these displacement machines, determine the speed and position of the device.

This makes it possible to control the primary drive primarily, while the secondary drive from the high-pressure storage and third hydraulic compressor is controlled secondarily. This effectively avoids the problems that prevented a practical implementation of the energy-efficient secondary control. Previously secondary-controlled drives were difficult to control from a regulatory point of view, as moment differences immediately led to a movement of the device. Since in practice, tolerances in the hydraulic components, hysterics and similar interference effects cannot produce a 100% ideal rotary speed, the potential for acceleration of the thrust is greatly reduced by the invention of a secondary thrust controlled by a regular combination of a primary or a secondary thrust controlled by a particularly high-energy thrust or a highly uncontrolled thrust.

The advantage is that the high pressure storage can be charged by the first hydraulic compressor, which is already present in the hydraulic drive system of the invention and can be connected or connected to the drive unit to supply the hydraulic energy to drive the second hydraulic compressor. In phases where the hydraulic energy provided by the first hydraulic compressor is not or not fully used by the second hydraulic compressor, this hydraulic energy can be stored in the high pressure storage according to the invention and then be available in operation with high load gas to support the drive unit.

In the case of a high-pressure storage device, the first hydraulic compressor is connected to the first hydraulic compressor by means of a valve. In the case of phases in which the high-pressure storage device is to be charged by means of the drive unit and the first hydraulic compressor, the high-pressure storage device is connected to the primary hydraulic circuit by means of this valve. In the case of phases in which the hydraulic energy stored in the high-pressure storage device is used to drive the device, the high-pressure storage device is separated from the primary hydraulic circuit and the device is connected by means of the third hydraulic compressor.

The connection is furthermore drinkable, and the storage management of the invention can be effectively controlled by such a flow control valve.

Alternatively, the invention may provide for a fourth hydraulic displacement machine through which the high pressure storage can be charged, which, in addition to the aforementioned advantages of efficient and flexible storage management, provides a flexible design of the rest of the hydraulic system, since the primary hydraulic circuit from the first and second hydraulic displacement machines can be operated independently of the second hydraulic circuit from the fourth hydraulic displacement machine, high pressure storage and third hydraulic displacement machine.

Such an embodiment of the invention thus comprises a drive unit, a first and a fourth hydraulic displacement machine with which the drive unit for the transmission of mechanical energy can be connected or connected, and a second and a third hydraulic displacement machine which can be connected or connected to the device for the transmission of mechanical energy, the first hydraulic displacement machine being hydraulically connected or connected to the second hydraulic displacement machine.

This results in a primary hydraulic circuit consisting of a first and second hydraulic compressor, through which the device can be hydraulically driven. The fourth and third hydraulic compressor, on the other hand, are used to effectively manage the storage of the high pressure storage. By connecting or connecting the fourth hydraulic compressor to the primary drive unit and at the same time connecting or connecting the third hydraulic compressor to the device, both the high pressure storage system and the energy recovery system achieve optimal efficiency and good use of the drives provided by the four primary drive units.

The invention also provides an advantage in that the high-pressure storage device can be charged by the third hydraulic compressor by acting as a hydraulic pump. This makes it possible to store the mechanical energy transferred from the device to the drive system during the phases in which the device is to be brake. Here too, the efficiency is excellent, since the mechanical energy from the device is converted directly into hydraulic energy by the third hydraulic compressor and can be fed into the high-pressure storage device. This also reduces the energy consumption of the system.

The advantage is that the high-pressure storage can be charged by the first or fourth hydraulic displacement machine or by the third hydraulic displacement machine, depending on the operating condition, so that the high-pressure storage can be charged by the drive unit or the device, but the efficiency is excellent.

The hydraulic compressor used for charging is connected to a hydraulic reservoir, which is also advantageous. In energy storage, hydraulic fluid can be pumped out of the hydraulic reservoir and pumped into the high-pressure storage.

The advantage of this method is that the third and/or fourth hydraulic displacement machine is connected to a hydraulic reservoir according to the invention.

If the high pressure storage is charged by the first hydraulic compressor, the design depends on whether the primary hydraulic circuit is open or closed. In an open primary hydraulic circuit, the first hydraulic compressor is connected to the hydraulic reservoir and can charge it if the high pressure storage is connected to the output of the first hydraulic compressor operating as a hydraulic pump.

Furthermore, the third hydraulic compressor works as a hydraulic motor and is driven by the high-pressure storage device. This makes it possible, in phases of high load, to return the hydraulic energy stored in the high-pressure storage device to the drive system and to propel the device. This again results in an excellent efficiency, since the hydraulic energy is converted directly by the third hydraulic compressor into mechanical energy, which then drives the device.

It is also advantageous that the first and/or fourth hydraulic compressor can operate as a hydraulic motor and be driven by the high pressure storage, which makes it possible to supply energy to other consumers driven in parallel by the drive unit, again with a good efficiency.

Furthermore, it is advantageous that the first hydraulic compressor can also operate as a hydromotor and the second hydraulic compressor as a hydraulic pump, so that the second compressor drives the first hydraulic compressor, which makes it possible, for example, to transfer energy to other consumers, which are driven by the drive unit in parallel, via the second and first hydraulic compressor circuits during the device's braking phases.

According to the invention, the first and second hydraulic compressor machines are advantageously combined in a closed hydraulic circuit. Such a closed hydraulic circuit of the first and second hydraulic compressor machines for the propulsion of the device is of great advantage for many applications, but prevents the efficient recovery of energy or efficient storage management of the hydraulic propulsion systems known to date.

However, the use of a third hydraulic compressor connected to the high pressure storage unit and the rechargeability of the high pressure storage unit by a hydraulic compressor connected to the drive unit now make it possible to perform efficient storage management and energy storage and recovery with high efficiency even in a closed hydraulic circuit from the first and second hydraulic compressors.

However, the present invention can of course also be used to advantage when the first and second hydraulic displacement machines form an open hydraulic circuit.

According to the invention, the waves of the second and third hydraulic displacement machines for the transmission of mechanical energy can be connected or connected to a drive shaft of the device, which allows mechanical energy from the second and third hydraulic displacement machines to be effectively transferred to the drive shaft of the device and vice versa.

Furthermore, the shafts of the second and third hydraulic compressor are connected directly or by means of a gearbox, which ensures that the shafts of the second and third hydraulic compressor are tightly coupled, resulting in a simple design with a high efficiency.

Furthermore, it is advantageous to connect the shafts of the second and/or third hydraulic displacement machine to the drive shaft of the device by at least one coupling, which enables the connection of the invention to be effectively established for the transmission of mechanical energy if necessary.

Furthermore, it is advantageous to connect the drive shaft of the drive unit to the drive shafts of the first and/or fourth hydraulic displacement machines for the transfer of mechanical energy, which allows the first and/or fourth hydraulic displacement machines to be driven by the drive unit and thus convert the mechanical energy provided by the drive unit into hydraulic energy.

Furthermore, it is advantageous that the drive shafts of the first and fourth hydraulic displacement machines can be connected to the drive shaft of the drive unit independently by at least two clutches, which makes it possible to control the first or fourth hydraulic displacement machine independently, so that, for example, only the first hydraulic displacement machine is driven or only the fourth hydraulic displacement machine, or both.

The power unit is also advantageous in that it drives the drive shafts of the first and/or fourth hydraulic displacement machine via a gearbox, which then provides the corresponding translation to drive the first and/or fourth hydraulic displacement machine.

The invention also provides for a further device to be driven by the drive unit, which is operated in parallel with the first and/or fourth hydraulic displacement machines. For example, if the first device is the lifting unit of a crane, the fourth device may be the cranes' cranes or rotors, so that several cranes can be driven by a single drive unit.

Furthermore, it is advantageous to drive the other device by means of a hydraulic circuit with a hydraulic pump, whereby the hydraulic pump is driven by the drive unit, which is used to drive several hydraulic circuits to drive several devices.

Furthermore, it is advantageous to have the additional device or the hydraulic pump driving the additional device connected to the drive unit by at least one coupling, independently of the first and/or fourth hydraulic displacement machines, so that the individual devices can be driven independently of each other by the drive unit.

Furthermore, it is advantageous that the further device or the hydraulic pump driving the further device can be connected to the first and/or fourth hydraulic displacement machines for the transfer of mechanical energy, in particular via at least one coupling. This makes it possible to transfer energy from the first and/or fourth hydraulic displacement machines to the further device or the hydraulic pump driving the further device, so that the further device can also be involved in storage management or energy recovery. However, this results in less efficient efficiency for the further device, since this hydraulic energy must first be converted into mechanical energy and then back into hydraulic energy. The connection of the further hydraulic displacement machine and/or the further hydraulic displacement machine with the further device or the further component can then be carried out via a common transmission unit, which can then be used to transfer energy between the individual components of the further hydraulic displacement device or the further unit.

The hydraulic drive system of the invention enables the drive unit to operate at an optimal operating point, since energy can be stored in low-load phases by means of the high-pressure storage and energy can be fed into the system in high-load phases to relieve the engine power of the drive unit. It also makes it possible to drive a drive unit with relatively high power output.

The advantage of the present invention is that the drive unit according to the invention comprises a single motor. Instead of using two motors to increase the overall performance of the system, as is necessary without the high pressure storage management according to the invention, a single motor is sufficient in the present invention, as load peaks can be deflated through the high pressure storage. Alternatively, several motors driving a gearbox can also be used in parallel, as the connection of the drive unit to the first and/or fourth hydraulic displacement machine ensures optimal utilization of the individual motors, storing unneeded drive energy.

Furthermore, it is advantageous to use the first and/or second hydraulic displacement machines according to the invention with adjustable displacement volumes, which can then be used to control the hydraulic circuitry of the first and second hydraulic displacement machines accordingly.

Furthermore, it is advantageous that the third and/or fourth hydraulic compressor of the hydraulic drive system of the invention has an adjustable compressor volume. The adjustability of the fourth hydraulic compressor thus allows the energy storage or energy release of this compressor to be controlled, the energy recovery from the device or the corresponding additional drive of this device to be controlled by the adjustability of the third hydraulic compressor.

It is also advantageous that the first and/or second hydraulic compressor have two conveying directions, which makes it possible to move the device in two directions via the first and second hydraulic compressor.

Furthermore, the advantage of the invention is that the third and/or fourth hydraulic compressor has two conveyor lines, which makes it possible to operate the third and/or fourth hydraulic compressor as both pump and motor without the need for a circuit, by switching from one conveyor to the other.

Furthermore, the invention provides for two devices, the propulsion systems of which are each equipped with a first, second and third hydraulic compressor, the first hydraulic compressor being capable of being connected or connected to the drive unit for the transfer of mechanical energy and the second and third hydraulic compressor being capable of being connected or connected to the devices for the transfer of mechanical energy, and the first hydraulic compressor being capable of being connected or connected hydraulically to the second hydraulic compressor. In essence, this results in two parallel hydraulic propulsion systems of the first, second and third compressors. The compressor of the invention is also capable of being connected to the devices, and the first hydraulic compressor is capable of being connected or connected hydraulically to the second hydraulic compressor.

The energy storage by the drive unit can be done by one or both of the first hydraulic displacement machines, and the high pressure storage can be connected to the output of at least one of the first hydraulic displacement machines via one or more valves.

Alternatively, energy storage can be achieved by a fourth hydraulic displacement machine, which can store energy directly from the drive power of the drive unit, but only a single fourth hydraulic displacement machine is required to achieve optimum efficiency.

The advantage of the hydraulic drive system according to the invention is that it has a control to control the storage and working functions of the system, which then takes over the control of the system components in order to either store energy in the high pressure storage or return this energy to the system in the individual phases.

The advantage of the hydraulic drive system of the present invention is that it is the drive system of a crane, where the storage management of the present invention can be used with great advantage.

The advantage is that the device is a blast, in particular a blast, which allows the free energy to be recovered by the third hydraulic compressor when loading and the high pressure storage to support the drive unit when lifting the loads. It is also possible to charge the high pressure storage by the first or fourth hydraulic compressor when the drive unit is otherwise not turning. This results in both a significant increase in power and massive energy savings. Thus, the primary drive power can be reduced despite increased exhaust power.

However, the hydraulic drive system of the invention can also be used to drive a mobile work equipment, in particular a reachstacker or wheel loader.

The device is preferably a drive, so that energy can be recovered when braking and then made available when accelerating.

The present invention continues to include a crane with a hydraulic drive system as described above, which gives the same advantages as described above.

The present invention also covers a mobile work equipment, in particular a reachstacker or wheel loader, with a hydraulic drive system as described above, which also gives the advantages described above.

The present invention further comprises a method for operating the propulsion system according to the invention, whereby the high pressure storage is charged by converting the motion energy of the device via the third hydraulic displacement machine and/or the high pressure storage is charged via a hydraulic displacement machine connected or connectable to the drive unit for the transmission of mechanical energy, when the power of the drive unit is not or not entirely required for the propulsion of the device. This, on the one hand, prolongs the energy released, e.g. when the device is decelerated, and, on the other hand, allows the drive unit to be driven at an optimal operating point by storing the power of each hydraulic displacement machine directly in the hydraulic displacement machine, which results in the high power output being generated by the respective hydraulic displacement machine.

The invention allows the high-pressure storage to be charged by the drive unit without moving the device, which was not possible with conventional systems but now allows for significantly improved energy management.

It is advantageous to provide two hydraulic circuits of the first and second hydraulic displacement machines on the one hand and the fourth and third hydraulic displacement machines on the other, so that a division of labour is made which allows the simple control of the hydraulic system of the invention.

Furthermore, the device is advantageously driven by converting the hydraulic energy from the high pressure storage via the third hydraulic displacement machine, which allows the hydraulic energy stored there to be used to support the drive unit, which therefore requires a lower output power.

Furthermore, it is advantageous to convert hydraulic energy from the high pressure storage to mechanical energy from the first and/or fourth hydraulic displacement machines, which allows additional consumers to be powered at peak power levels also via the high pressure storage, but with a lower efficiency.

The present invention further comprises a hydraulic drive system for the propulsion of a device, with a drive unit capable of propelling the device via a primary hydraulic drive consisting of a hydraulic pump and a hydraulic motor, with a secondary hydraulic drive which is connected or connected to another hydraulic displacement machine for the transmission of mechanical energy to the device, with a high pressure storage unit which is connected or connected hydraulically to the secondary displacement machine, and with a control unit where the primary hydraulic drive is controlled by the primary and the secondary hydraulic secondary drives.

The present invention also includes a corresponding method for the propulsion of a device by means of a hydraulic drive system with a drive unit capable of propelling the device by means of a primary hydraulic drive from a hydraulic pump and a hydraulic motor, and with a secondary hydraulic drive which is connected or coupled to another hydraulic displacement machine for the transmission of mechanical energy to the device and a high pressure storage device which is connected or coupled hydraulically to the secondary displacement machine, the primary hydraulic drive being controlled by the primary and the secondary hydraulic drive by the secondary.

The primary hydraulic drive thus determines the speed or position of the device by the volume flow, so that minor inaccuracies in the secondary control of the further hydraulic displacement machine do not lead to an immediate, unwanted movement of the consumer. This results in enormous advantages over conventional secondary control drives, which had not been achieved until now, especially from a safety point of view, due to this problem of the control technique that is difficult to master.

The methods of the invention are advantageously performed automatically by the control of the hydraulic drive system of the invention.

The present invention is now described in more detail by means of illustrations and drawings showing: Figure 1a:an example of the hydraulic drive system of the invention for propelling a wind turbine with a closed primary hydraulic circuit, whereby the high pressure storage is chargeable via the first hydraulic compressor of the primary hydraulic circuit,Figure 1b:an example of the hydraulic drive system of the invention for propelling two devices, whereby two primary closed hydraulic circuits are provided, and whereby the high pressure storage is chargeable via the primary hydraulic circuit with the higher pressure,Figure 1c:an example of the hydraulic drive system of the invention, whereby two hydraulic compressors are connected to the first hydraulic compressor, whereby two hydraulic compressors are connected to the primary hydraulic circuit,Figure 2a:an example of the hydraulic drive system of the invention for propelling a wind turbine, with a closed primary hydraulic circuit, with a fourth hydraulic drive machine through which the high pressure storage can be charged,Figure 2b:an alternative version of the hydraulic drive system shown in Figure 2a,Figure 2c:an example of the hydraulic drive system of the invention for propelling a driving motor shown in Figure 2a,Figure 2d:an example of a hydraulic drive system for propelling a driving motor, with a second hydraulic drive system for propelling two consumers, with two additional primary drivers,Figure 2c:an example of a hydraulic drive system, which is designed to run on a hydraulic motor, which is connected to a hydraulic drive system, which is connected to a hydraulic motor, which is connected to a hydraulic motor, which is connected to a hydraulic drive system, which is connected to a hydraulic motor, which is connected to a hydraulic motor, which is connected to a hydraulic motor, which is connected to a hydraulic motor, which is connected to a hydraulic motor, which is connected to a hydraulic motor, which is connected to a hydraulic motor, which is connected to a hydraulic motor, which is connected to a hydraulic motor, which is connected to a hydraulic motor, which is connected to a hydraulic motor, which is connected to a hydraulic motor, which is connected to a hydraulic motor, which is connected to a hydraulic motor, which is connected to a motor, which is connected to a motor, which is connected to a motor, which is connected to a motor, which is connected to a motor, to a motor, which is connected to a motor, which is connected to a motor, to a motor, to a motor, which is connected to a motor, to a motor, a motor, which is connected to a motor, to a motor, a motor, which is connected to a motor, to a motor, a motor, a motor, to a motor, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, an, an,Figure 3a:an example of the hydraulic drive system of the invention for propelling a wind turbine with an open primary hydraulic circuit, whereby the high pressure storage is chargeable via the first hydraulic displacement machine of the primary hydraulic circuit,Figure 3b:an example of the hydraulic drive system of the invention for propelling the wind turbine, with two primary hydraulic cycles, which are charged by a single first hydraulic displacement machine with a hydraulic fluid displacement machine, whereby the high pressure storage is charged via the first hydraulic displacement machine on four further hydraulic displacement machines,Figure 4:An example of the hydraulic drive system of the invention, which is designed to be charged on a hydraulic displacement machine with a high pressure displacement machine, is shown below, and is designed to be used for a hydraulic displacement machine with a high pressure displacement machine, which is charged by a hydraulic displacement machine, with a high pressure displacement machine, which is open to a further four hydraulic displacement machines,Figure 4:An example of the hydraulic drive system of the invention, which is designed to be charged on a hydraulic displacement machine with a high pressure displacement machine, with a high pressure displacement machine, which is open to the first hydraulic displacement machine, and a high pressure displacement machine with a hydraulic displacement motor, which is charged on a secondary displacement machine, with a high pressure displacement machine, which is charged on a hydraulic displacement machine with a high pressure displacement machine, which is charged on a secondary displacement of the first hydraulic displacement machine, which is charged on a high pressure displacement of the first hydraulic displacement machine, and a high pressure displacement of the first hydraulic displacement system is charged on a high pressure displacement of the first hydraulic displacement machine, which is charged on a high pressure displaced by a high pressure displacement of the first hydraulic displacement motor, which is charged on a high pressureFigure 5a:an example of the hydraulic drive system of the invention for propelling a crane, with an energy recovery hydraulic drive system of the invention for propelling the winds and two additional hydraulic circuits for propelling the rotor and the winch,Figure 5b:an example of the hydraulic drive system of the invention for propelling a crane, with an energy recovery hydraulic drive system of the invention for propelling two winds and two additional hydraulic drives for propelling the winch and the winch,Figure 6a:another example of a hydraulic drive system of the invention for propelling a crane, with an energy recovery hydraulic drive system of the invention for propelling two winds and two additional hydraulic drives for propelling the winch and the winch,Figure 6a:an example of a hydraulic drive unit of the invention, with two hydraulic drives and a hydraulic drive unit, and the first unit of the engine, the two engines and the fifth unit, which are run parallel to the engine.

Figure 1a shows an example of the hydraulic drive system for propelling a winch according to the invention 6 whereby a diesel engine is provided as the drive unit 10 to drive the first hydraulic displacer 1. For this purpose, the drive unit 10 is connected to the first hydraulic displacer 1 by a clutch 7 and a gear 8 to the first hydraulic displacer 1. The first hydraulic displacer 1 is connected to a second hydraulic displacer 2 by hydraulic lines 11 and 13 so that a closed primary hydraulic circuit is formed. The second hydraulic displacer 2 is connected to and drives the first hydraulic displacer 6.

A third hydraulic compressor 3 is also planned, which is also connected to the winch 6 and is connected by hydraulic lines to a hydraulic reservoir 9 and a high pressure storage 5 and the hydraulic storage 5 is connected by a valve 70 to the first hydraulic compressor 1 via the pressure-side hydraulic line 11 of the primary hydraulic circuit.

If the first hydraulic compressor 1 is now driven by the drive unit 10, the primary hydraulic circuit drives the wind 6 via the second hydraulic compressor 2 so that a load can be lifted. If, on the other hand, the load from the wind 6 is lowered, the mechanical energy released can be converted into hydraulic energy in the third hydraulic compressor and stored in the high pressure storage 5 . This results in an excellent degree of mechanical torque by converting the mechanical energy directly into hydraulic energy.

Furthermore, in operating phases when the wind 6 is stationary or the propulsion energy required to operate the wind 6 is less than that supplied by the drive unit 10, the valve 70 of the high pressure storage unit 5 can be connected to the output of the first hydraulic pressure storage unit 1 by switching to the valve 70 to charge the first hydraulic pressure storage unit 5.

The hydraulic fluid, which is pumped into the high pressure storage 5 by the first hydraulic compressor machine 1 during storage operation, is supplied by a smaller feed pump 90 which supplies the low pressure side 13 with a minimum pressure via a back-up valve 91 and thus compensates for leakage oil losses in known closed hydraulic circuits.

According to the invention, the high pressure storage 5 can be charged directly by a hydraulic compressor connected to the drive unit 10 for the transfer of mechanical energy, which allows it to store energy with excellent efficiency even when the wind 6 is stationary. This allows the drive unit 10 to be operated, e.g. in the form of a diesel engine, at an optimal operating point, with the mechanical energy provided by the drive unit 10 being used to drive the wind 6 or stored in the high pressure storage 5.

The first, second and third hydraulic compressors are two-way adjustable pumps, the position of which controls the hydraulic system. The volume flow through the closed hydraulic circuit from the first and second hydraulic compressors determines the movement of the wind, while the third hydraulic compressors are driven by wind 6 or wind 6 depending on the load situation. The primary hydraulic circuit can be primarily controlled while the third hydraulic drive unit is secondarily controlled, so that the respective advantages (safe and reliable actuation at primary regulation and effective secondary energy recovery regulation) can also be combined while the secondary energy is regulated at the nearest to the primary.

Figure 1b shows another example of the hydraulic drive system of the invention for the propulsion of two consumers. It consists of two closed primary hydraulic circuits for the propulsion of the respective consumers, which essentially correspond to the primary hydraulic circuits shown in Figure 1a. The first hydraulic compressors 1 and 21 of the respective primary hydraulic circuits are driven by the drive unit 10 in parallel via gear 8 and are hydraulically connected to the second hydraulic compressors 2 and 22 each, which drive the first and third devices.The high pressure storage 5 is further connected to a valve arrangement 71 via a valve 70; the valve arrangement 71 comprises two back-up valves, through which the connection line 74 between valve 70 and valve arrangement 71 is connected to the pressure side 72 and 73 of the primary hydraulic circuits respectively. The hydraulic storage in the example shown in Figure 1b corresponds essentially to the storage shown in Figure 1a, whereby in the open position of valve 70 the high pressure storage 5 can be charged via the primary hydraulic circuit at the higher pressure.

The example shown in Figure 1b makes it possible to operate the energy storage modes of the invention by means of either the first or third hydraulic compressors in the same way as in Figure 1a. The hydraulic energy stored in the high pressure storage tank 5 can also be used by means of the third hydraulic compressors 3 and 23 to drive the two devices.

Figure 1c shows a further version of the propulsion system of the invention, which drives two devices as shown in Figure 1b. The primary propulsion circuits are identical to those shown in Figure 1b, while the valve arrangement 71 is replaced by separate control valves 70 and 80, which are connected via the high pressure storage 5 to the pressure side 72 and 73 of the primary hydraulic circuits respectively. The valves 70 and 80 operate in a manner analogous to the valve 70 shown in Figure 1a, so that a charge of the high pressure storage 5 is possible via the respective first hydraulic displacement machines 1 and 21 of the respective primary hydraulic circuits.

In the examples shown in Figures 1b and 1c, the hydraulic fluid is supplied by the first hydraulic compressors 1 and 21 to the high pressure storage tank 5 as shown in Figure 1a, via the respective oil leakage stream compensation, which is supplied by a feed pump not shown.

Figure 2a shows another example of the hydraulic drive system of the invention for propelling a winch 6 of a crane, in which the high pressure storage is charged by a fourth hydraulic displacement unit 4; the diesel engine is also provided as the driving unit 10 and is connected to a gearbox 8 by a clutch 7; the gearbox 8 is connected to a first hydraulic displacement machine 1 and a fourth hydraulic displacement machine 4. The overclutch 7 and the gearbox 8 enable the drive unit 10 to drive the first hydraulic displacement machine 1 and the fourth hydraulic displacement machine 4.

The first hydraulic compressor 1 is connected to a second hydraulic compressor 2 via the hydraulic lines 11 and 13, so that a hydraulic circuit is formed from the first and second hydraulic compressors. The second hydraulic compressor 2 is in turn connected to the wind 6 and drives it. The hydraulic circuit from the first and second hydraulic compressors is a closed hydraulic circuit in the example, so that in the circuit from the first hydraulic compressor 1, Hydraulic compressor 11, second hydraulic compressor 2 and hydraulic compressor 13 when the first hydraulic compressor is driven by the pump unit and operates as a hydraulic actuator, the hydraulic circuit is hydraulically actuated.

A third hydraulic compressor 3 is also provided, the drive shaft of which is directly connected to the drive shaft of the second hydraulic compressor. The fourth hydraulic compressor 4 and the third hydraulic compressor 4 are connected to the high pressure storage 5 by hydraulic lines 12 and 14. In the respective pumping operation of the fourth and third hydraulic compressor respectively, this hydraulic fluid can be pumped from a hydraulic compressor 9 back into the high pressure storage 5 respectively. Conversely, in the operation of the fourth and third hydraulic compressor 5 the hydraulic fluid can flow from the hydraulic compressor 5 through the respective hydraulic compressors 9 so that these hydraulic compressors 9 work as a hydraulic motor.

Thus, in the hydraulic drive system of the invention, there is a direct possibility of transferring mechanical energy from the drive unit 10 to both the first and fourth hydraulic displacement machines, and there is a direct possibility of transferring mechanical energy from the second and third hydraulic displacement machines to the wind 6 or vice versa from wind 6 to the second and third hydraulic displacement machines.

The wind 6 can now be driven first by the closed hydraulic circuit from the first and second compressor, whereby the mechanical energy supplied by the drive unit 10 is converted by the first hydraulic compressor into hydraulic energy and by the second hydraulic compressor into mechanical energy, which drives the wind 6. Conversely, if mechanical energy is transferred from the wind 6 back to the hydraulic drive system, as is the case with a reduction in the load of the hydraulic energy, the hydraulic energy must now no longer be destroyed or stored at the drive unit 10 as in existing systems, but drives the third hydraulic compressor into the pump 3 which now operates as a pump and produces a hydraulic fluid. In the case of the conversion of the hydraulic energy, the energy can be stored in the pump 5 without further conversion of the hydraulic fluid.

Conversely, when lifting a load through the winch 6, the winches can also be driven by the third hydraulic compressor machine 3, with hydraulic fluid flowing from the high pressure storage 5 to the hydraulic reservoir 9. This supports the drive via the hydraulic circuit from the first and second hydraulic compressors, so that the drive unit 10 can also be reduced in size. The efficiency is again very high by directly converting the hydraulic energy from the hydraulic storage into mechanical energy that drives the winch 6, so that an overall effective energy recovery can be achieved.

In addition, the high pressure storage 5 can also be charged via the fourth hydraulic compressor 4 if the energy supplied by the drive unit 10 is not or not entirely required to drive the first hydraulic compressor 1. This in particular makes it possible to operate the diesel engine of the drive unit 10 at an optimal operating point, charging the high pressure storage 5 in phases where little power is required to drive the wind 6 and in phases where particularly high power is required, returning the energy from the high pressure storage 5 and using the third hydraulic compressor to drive the wind machine.

The volume current from the closed hydraulic circuit of the first and second hydraulic compressor determines the movement of the winds, while the third hydraulic compressor is driven by the wind 6 or drives the wind 6 depending on the load situation, and the fourth hydraulic compressor 4 charges or does not charge the high pressure storage 5 depending on the operating situation.

In the example, all hydraulic compressors are designed as adjustable compressors with two conveyor lines, all of which can operate as both hydraulic pumps and hydraulic motors.

The third hydraulic compressor machine usually works as both a pump and a motor, wherein in the example the alternation between these functions can be made by the direction of the compressor. The adjustability of the third hydraulic compressor machine allows, in addition to switching between pump and motor operation, the control of the pump and the control of the energy output of the hydraulic compressor.

The embodiment of the hydraulic drive system of the invention shown in Figure 2b is largely identical to the hydraulic drive system shown in Figure 2a, so that no further description of the corresponding components is required. The only difference with the first embodiment shown in Figure 2a is that the second and third hydraulic displacement machines are connected to the winch 6, which in the fourth example is now connected via the intermediate third gear 17.

Figure 2c shows an example of the hydraulic drive system of the invention, which is identical in its components to the drive shown in Figure 2a, but is not used to drive a crane but to drive a mobile work equipment, in this case a reachstacker or wheel loader, where the driver is first hydraulically operated via the closed hydraulic circuits of the first and second hydraulic power transmission engines 1 and 2, whereby the energy released by the vehicle's braking is now generated via the third hydraulic power transmission engine 3 in the pressure storage unit 5 and stored in the high-pressure drive and returned to the engine at high speed, so that the hydraulic power transmission can be operated directly by a hydraulic motor unit 4 and 5 which can only be operated by the second hydraulic power transmission unit 5 and the hydraulic power transmission unit 5 can be operated by a hydraulic motor unit 10 which is the most efficient unit for the vehicle.

The example shown in Figure 2d now provides for two devices which can be driven separately by the hydraulic drive system. For example, in the case of a crane, both the winches and the rotor or two winds could be driven by the hydraulic drive system. The drive unit 10, a diesel engine, drives two parallel first hydraulic pushers 1 and 21 and a fourth hydraulic pusher 4 by means of a clutch 7 and a gear 8 and the first hydraulic pusher 1 forms a closed hydraulic circuit, which in the previous examples is connected to a second hydraulic pusher 2, which in turn is connected to the first gear. The first hydraulic pusher 22 and the second hydraulic pusher 23 are also connected to a hydraulic circuit, which in turn is connected to a second hydraulic pusher 2 and a second hydraulic pusher 2.

This makes it possible, in the case of energy recovery, to convert the mechanical energy supplied by the respective device directly via the hydraulic compressor 3 or 23 into hydraulic energy, which is then stored in a common high pressure storage 5 . To this end, the two third hydraulic compressor 3 and 23 are connected to the high pressure storage 5 via hydraulic lines 14 and 19 respectively. Likewise, both devices can be directly powered by the respective third hydraulic compressor 5 using the pressure from the high pressure storage 5 via the respective third hydraulic compressor. To directly charge the compressor 5 via the drive unit 10 the fourth hydraulic compressor 4 is also connected to a hydraulic motor 12 via the hydraulic drive unit 5 or 10 so that it can only be operated at a minimum load of 10 volts, so that the two hydraulic compressor units can only be recharged at a maximum load of 10 volts.

The energy management of the invention can thus be used with optimum efficiency for the propulsion of two consumers without the need to completely double the propulsion system. For the additional consumer, in addition to the drive from the first and second hydraulic displacement machines 21 us 22 which is necessary in any case, only a third hydraulic displacement machine 23 is needed as an additional element, while the fourth hydraulic displacement machine 4 and the high pressure storage system 5 do not need to be doubled. On the contrary, the common high pressure storage system 5 allows a simple energy exchange between the two drives for the first and second device.

The example shown in Figure 2e is a three-device drive system, the drive system for the first two devices being identical to the one shown in Figure 2d, so that no description of these system components is required. The gearbox 8, driven by the drive unit 10, now drives the first hydraulic compressor 1 and 21 of the first two devices and the fourth hydraulic compressor 4 as well as the first hydraulic compressor 31 of the third device, which is placed parallel to it. The first hydraulic compressor 31 of the third device forms a hydraulic circuit with the other hydraulic compressor 32,The third device is now equipped with no additional displacement machine, so that in the event of a braking operation the third device of the high pressure storage 5 cannot be charged directly. However, in the event of a braking operation of the third device, it is possible to convert the mechanical energy from the third device first into hydraulic energy via the hydraulic displacement machine, to convert this hydraulic energy back into mechanical energy via the hydraulic displacement machine 31 and then to supply this mechanical energy via the transmission 8 to the other hydraulic displacement machines, so that, for example, the hydraulic energy is converted into mechanical energy via the hydraulic displacement machine 31 and the mechanical energy is then transferred to the other hydraulic displacement machines.The first and second devices, which allow the direct conversion of mechanical energy into hydraulic energy by the third hydraulic machines, are much less efficient.

Figure 3a shows another example of the hydraulic drive system of the invention for propelling a winch 6 using an open primary hydraulic circuit. The first hydraulic compressor 1 is driven by the drive unit 10 with which it is connected via the clutch 7 and provides the pressure for the entire hydraulic system. The first hydraulic compressor 1 is a hydraulic pump with a conveyor and adjustable full current. The output 46 of the first hydraulic compressor 1 is driven by a 4/3 valve 40 valve with the connections 42 and 43 of the second hydraulic compressor 2, which drives 6 winds, which are connected to the water supply.The valve 40 is connected to the hydraulic reservoir 9 in each case, and has a middle position in which both outputs 42 and 43 are connected to the hydraulic reservoir 9. Furthermore, in the high pressure side connection line 42 of the second hydraulic compressor 2 there is a valve 41 controlled by a control line 44 which is connected to the low pressure axis 43. If the hydraulic compressor 43 is not loaded with pressure, the valve 41 provides a hydraulic valve which prevents the return of hydraulic flow from the second hydraulic compressor to the first hydraulic compressor.In the reverse case, the valve 41 is an adjustable throttle.

Furthermore, a third hydraulic compressor 3 according to the invention is capable of connecting to the winch 6 via a coupling 47 and is hydraulically connected to the high pressure storage 5 for the transfer of mechanical energy, so that the mechanical energy given off by the winch 6 can be converted to hydraulic energy via the third hydraulic compressor 3 and stored in the high pressure storage 5 and, conversely, the hydraulic energy stored in the high pressure storage 5 can be used via the third hydraulic compressor to drive the winch 6 and thus support the drive unit 10.

The high pressure storage 5 is now connected by a valve 70 to the output side 46 of the first hydraulic compressor 1; this arrangement essentially allows operation as in the example of the present invention shown in Figure 1a, whereby the first hydraulic compressor 1 when charging the high pressure storage 5 draws the hydraulic fluid required directly from the reservoir 9 as it is an open hydraulic circuit.

In Figure 3b, a further embodiment of the present invention is shown using the two-wind drive arrangement used in Figure 3a. This is done by two second hydraulic compressors 2 and 22 which drive the first and second winds respectively and are driven by valves 40 and 41 and 80 and 81 respectively as in the first hydraulic compressors 1 shown in Figure 3a. In addition, there are three hydraulic compressors 3 and 23 respectively, each of which is connected to the first and second winds by couplers and is hydraulically connected to a hydraulic reservoir and to the other side by a hydraulic pump.

The high pressure storage tank 5 can thus be charged with the energy from the winds via the third hydraulic compressors 3 and 23 respectively, and the energy stored in the high pressure storage tank 5 can be used to drive the winds.

Furthermore, in operating phases where the propulsion energy supplied by the drive unit 10 is not or not entirely required by the second hydraulic compressors 2 and 22 to drive the winds, it is possible to store the remaining energy in the hydraulic storage 5 and this also results in the advantages described above in relation to the closed primary hydraulic circuits, which also occur in the open primary hydraulic circuits shown here.

Figure 4 shows another example of an open primary hydraulic hydraulic drive system of the invention, where the high pressure storage 5 can be charged by a fourth hydraulic displacement machine, the primary hydraulic drive corresponding to the example shown in Figure 3a and the storage corresponding to the example shown in Figure 2a.

The first hydraulic compressor 1 is an adjustable pump which connects via valves 40 and 41 to the respective inlet side of the second hydraulic compressor 2 and via valve 40 to the hydraulic reservoir 9; valve 40 is a 4/3 way valve which connects the connections of the second hydraulic compressor 1 to the hydraulic reservoir in a central position and, in the two outer switch positions, the pressure relief valve 1 to the pressure relief valve 1 via either the hydraulic pump 42 or the hydraulic pump 43 to the two outlets of the second hydraulic compressor 2 and the second hydraulic compressor 2 to the hydraulic compressor 9 respectively. In the case of a hydraulic compressor, this valve is designed to be operated in the same direction, in particular if the hydraulic compressor is not connected to the other hydraulic compressor, and if the hydraulic compressor is not connected to the second hydraulic compressor, the hydraulic compressor 43 is designed to be operated in the opposite direction.

The arrangement of the fourth hydraulic compressor, the third hydraulic compressor and the hydraulic storage 5 is again identical to the examples shown in Figures 2a to 2e, so that these are not discussed in detail.

In addition, another consumer is provided in Fig. 4 which is driven by a separate hydraulic circuit without its own energy storage.

Figure 5a shows a hydraulic drive system of a crane, using the direct energy recovery for the lift according to the invention, while the winch and the rotor are driven in parallel by their own hydraulic circuits without their own energy recovery. The drive system of the lift 6 essentially follows the example shown in Figure 2a, with the addition of clutches 52 and 51 between the gear 8 and the first and second hydraulic displacement machine respectively. Furthermore, a further 6 clutches are provided between the four hydraulic displacement machines mounted on a common axis and the second and eighth hydraulic displacement machines and the lift 55 .

In addition, the turbine 58 and turbine 63 are now intended as additional devices to be driven by the hydraulic system, the transmission 8 being connected via the clutch 53 to an adjustment pump 57 which drives the hydraulic cylinder of the turbine 58.

Furthermore, the transmission 8 is connected via clutch 54 to a hydropump 59 which, together with a hydromotor 60, forms a closed hydraulic circuit which, via a clutch 56, drives the rotor 63.

Neither the coupling between gears and hydraulic displacement machinery nor the coupling between hydraulic displacement machinery and devices is absolutely necessary, so that some or all of the couplings could be omitted in alternative embodiments.

As shown in Figure 2e, the energy recovery from the movement of the tiller and the rotor cannot be done directly, as in the case of the crane, but only by way of the gear 8 bypass, so that the efficiency is correspondingly lower there.

In Figure 5b, another example of the hydraulic drive system for propelling a crane is shown, which is similar in the whip and rotor to the one shown in Figure 5a and now includes two winds in the hydraulic energy storage system of the invention. The hydraulic drive system for propelling the two winds is similar to the one shown in Figure 2d, i.e. it has a closed primary hydraulic circuit of first hydraulic compressor 1 and 21 respectively and second hydraulic compressor 2 and 22 respectively, while the propulsion is provided by three hydraulic compressors 2 and 23 respectively, and a hydraulic unit connected to the fourth compressor 10 and the hydraulic compressor 10 respectively.

The operation of the drive system shown in Figure 5b is essentially the same as that of the drive system shown in Figure 5a, but with the possibility of energy recovery from the movement of two winds and of supporting the drive by means of the hydraulic energy stored in the high pressure storage 5 also for both winds.

As described above, the invention of the crane drives shown in Figures 5a and 5b results in massive energy savings in the turning operation by the direct energy recovery from the lift by the third hydraulic compressor 3 and the use of the high pressure storage 5 and the third hydraulic compressor 3 as a secondary power source for increasing the power without the need to increase the primary power of the drive unit 10.

The direct energy storage of the energy emitted by the drive unit 10 via the fourth hydraulic displacement machine 4 continues to allow the diesel engine of the drive unit 10 to operate at an optimal operating point, since unneeded energy can be effectively stored.

It is also possible, at peak loads, to use the high pressure storage 5 as a secondary source of power in the propulsion of the piston or rotor by the fourth hydraulic displacement machine acting as a hydromotor and delivering mechanical energy via the transmission 8 to the other consumers.

Of course, the same advantages described for a wind turbine with a closed primary hydraulic circuit and a fourth hydraulic compressor, through which the high pressure storage 5 can be charged, can also be achieved by choosing one of the alternatives described above for the wind turbine.

The only decisive factor is that the high-pressure storage 5 is rechargeable via a hydraulic compressor which is connected or can be connected to the drive unit 10 for the transmission of mechanical energy, so that energy not required to drive the wind can be efficiently stored, especially when the wind itself is stationary.

In Figure 6a, we now see another example of the hydraulic drive system of the invention, which is essentially the same as the drive system shown in Figure 2a. However, it involves two drive motors 10 and 110, which are connected to the gearbox 8 via clutches 7 and 107 respectively, which in turn drive the first and fourth hydraulic displacement machines. In the case of electric drive motors in particular, such an arrangement may be advantageous in providing the required power.

The embodiment of a hydraulic drive system according to the invention shown in Figure 6b is firstly a first subsystem corresponding to the system shown in Figure 2a. In parallel to this, a second subsystem is provided in which a further drive unit 120 drives a further hydraulic drive 101 and a further fourth hydraulic drive 104 by means of a clutch 117 and a gear 108 which are hydraulically parallel to the first and fourth hydraulic drives of the first subsystem. This results in both a power doubling of the whole drive system and a redundant layout which increases the safety of the whole drive system. The operation of this system is designed to be analogous to that of the hydraulic drive unit in Figure 2 and is designed to be simple and simple, while the second drive unit is designed to be a hydraulic drive unit and a simple and simple propulsion unit.

The same advantages as shown above are also achieved with this drive system, with the additional redundancy of the hydraulic pressure supply.

Claims (38)

1. A hydraulic drive system for driving an apparatus (6), with a drive unit (10) which can drive the apparatus (6) via a primary hydraulic circuit comprising a first hydraulic displacement machine (1) and a second hydraulic displacement machine (2), and with a third hydraulic displacement machine (3) which is connectable or connected with the apparatus (6) for transmitting mechanical energy, and a high-pressure accumulator (5) which is hydraulically connected or connectable with the third displacement machine (3), so that via the third hydraulic displacement machine an energy recovery or a support of the drive system can be effected, which is independent of the primary hydraulic circuit, wherein shafts of the second hydraulic displacement machine (2) and the third hydraulic displacement machine (3) are connectable or connected with a drive shaft of the apparatus (6) for transmitting mechanical energy, characterized in that the high-pressure accumulator (5) can be charged by a hydraulic displacement machine which is connected or connectable with the drive unit (10) for transmitting mechanical energy such that a direct conversion of the mechanical energy supplied by the drive unit into hydraulic energy is effected by the hydraulic displacement machine.
2. The hydraulic drive system according to claim 1, wherein the high-pressure accumulator (5) can be charged by the first hydraulic displacement machine (1).
3. The hydraulic drive system according to claim 1, wherein a fourth hydraulic displacement machine (4) is provided, via which the high-pressure accumulator (5) can be charged.
4. The hydraulic drive system according to any of the preceding claims, wherein the high-pressure accumulator (5) can be charged via the third hydraulic displacement machine (3), in that the same operates as hydraulic pump.
5. The hydraulic drive system according to any of the preceding claims, wherein the hydraulic displacement machine used for charging is connected or connectable with a hydraulic reservoir (9).
6. The hydraulic drive system according to any of the preceding claims, wherein the third hydraulic displacement machine (3) operates as hydraulic motor and can be driven via the high-pressure accumulator (5).
7. The hydraulic drive system according to any of the preceding claims, wherein the first and/or fourth hydraulic displacement machine operates as hydraulic motor and can be driven via the high-pressure accumulator (5).
8. The hydraulic drive system according to any of the preceding claims, wherein the first hydraulic displacement machine (1) also can operate as hydraulic motor and the second hydraulic displacement machine (2) also can operate as hydraulic pump, so that the second hydraulic displacement machine drives the first hydraulic displacement machine.
9. The hydraulic drive system according to any of the preceding claims, wherein the first and the second hydraulic displacement machine form a closed hydraulic circuit.
10. The hydraulic drive system according to claim 1, wherein the shafts of the second and the third hydraulic displacement machine are connected directly or via a transmission (17).
11. The hydraulic drive system according to claim 1, wherein the shafts of the second and/or the third hydraulic displacement machine are connectable with the drive shaft of the apparatus (6) via at least one clutch (55).
12. The hydraulic drive system according to any of the preceding claims, wherein the output shaft of the drive unit (10) is connectable or connected with drive shafts of the first and/or the fourth hydraulic displacement machine for transmitting mechanical energy.
13. The hydraulic drive system according to claim 12, wherein the drive shafts of the first and the fourth hydraulic displacement machine are independently connectable with the drive shaft of the drive unit via at least two clutches (51, 52).
14. The hydraulic drive system according to claim 12 or 13, wherein the drive unit (10) drives the drive shafts of the first and/or the fourth hydraulic displacement machine via a transmission (8).
15. The hydraulic drive system according to any of the preceding claims, wherein at least one further apparatus (63) is driven via the drive unit (10).
16. The hydraulic drive system according to claim 15, wherein the further apparatus (63) is driven via a hydraulic circuit with a hydraulic pump (59) and the hydraulic pump is driven by the drive unit (10).
17. The hydraulic drive system according to claim 15 or 16, wherein the further apparatus (63) or the hydraulic pump (59) driving the further apparatus (63) is connectable with the drive unit (10) via at least one clutch (54) independent of the first and/or the fourth hydraulic displacement machine.
18. The hydraulic drive system according to any of claims 15 to 17, wherein the further apparatus (63) or the hydraulic pump driving the further apparatus (63) is connectable with the first and/or fourth hydraulic displacement machine for transmitting mechanical energy, in particular via at least one clutch.
19. The hydraulic drive system according to any of the preceding claims, wherein the drive unit (10) comprises an internal combustion engine or an electric motor.
20. The hydraulic drive system according to claim 19, wherein the drive unit comprises a single motor or a plurality of motors (10, 110) driving a transmission in parallel.
21. The hydraulic drive system according to any of the preceding claims, wherein the first and/or the second hydraulic displacement machine has an adjustable displacement volume.
22. The hydraulic drive system according to any of the preceding claims, wherein the third and/or the fourth hydraulic displacement machine has an adjustable displacement volume.
23. The hydraulic drive system according to any of the preceding claims, wherein the first and/or the second hydraulic displacement machine has two directions of delivery.
24. The hydraulic drive system according to any of the preceding claims, wherein the third and/or the fourth hydraulic displacement machine has two directions of delivery.
25. The hydraulic drive system according to any of the preceding claims, wherein two apparatuses are provided, whose drive systems each have first, second and third hydraulic displacement machines, wherein the first hydraulic displacement machines (1, 21) are connectable or connected with the drive unit (10) for transmitting mechanical energy, the second hydraulic displacement machines (2, 22) and the third hydraulic displacement machines (3, 23) each are connectable or connected with the apparatuses for transmitting mechanical energy, wherein the first hydraulic displacement machines (1, 21) each are hydraulically connected or connectable with the second hydraulic displacement machines (2, 22), and wherein the high-pressure accumulator (5) is hydraulically connected or connectable with the third hydraulic displacement machines (3, 23).
26. The hydraulic drive system according to claim 25, wherein the high-pressure accumulator (5) can be charged by one or both of the two first hydraulic displacement machines (1, 21).
27. The hydraulic drive system according to claim 25, wherein a fourth hydraulic displacement machine (4) additionally is provided, via which the high-pressure accumulator (5) can be charged.
28. The hydraulic drive system according to any of the preceding claims, comprising a controller for activating the storage and work functions of the system.
29. The hydraulic drive system according to any of the preceding claims for driving a crane.
30. The hydraulic drive system according to claim 29, wherein the apparatus (6) is a winch, in particular a hoisting winch.
31. The hydraulic drive system according to any of claims 1 to 28 for driving a mobile implement, in particular a reachstacker or a wheel loader.
32. The hydraulic drive system according to claim 31, wherein the apparatus (6) is a traveling drive.
33. A crane with a hydraulic drive system according to any of claims 1 to 30.
34. A mobile implement, in particular a reachstacker or wheel loader, with a hydraulic drive system according to any of claims 1 to 28 and 31 and 32.
35. A method for operating a drive system according to any of the preceding claims, wherein the high-pressure accumulator (5) is charged by conversion of the kinetic energy of the apparatus (6) via the third hydraulic displacement machine (3) and/or the high-pressure accumulator (5) is charged via a hydraulic displacement machine which is connected or connectable with the drive unit (10) for transmitting mechanical energy, when the power of the drive unit (10) is not or not completely required for driving the apparatus (6).
36. The method according to claim 35, wherein charging the high-pressure accumulator (5) is effected while the apparatus (6) is not moved.
37. The method according to claim 35 or 36, wherein the apparatus (6) is driven by conversion of the hydraulic energy from the high-pressure accumulator (5) via the third hydraulic displacement machine (3).
38. The method according to any of the preceding claims, wherein mechanical energy is supplied to further loads by conversion of the hydraulic energy from the high-pressure accumulator (5) via the first and/or fourth hydraulic displacement machine.