Predominantly electrically operated earth working machine

Abstract

A self-propelled earth working machine includes a machine frame and a traveling gear, the traveling gear including drive units rollable on a contact subsurface of the earth working machine, the machine frame supporting a working apparatus, the earth working machine having as a main functional unit a work drive in order to drive the working apparatus to perform a work movement for earth working, and the earth working machine having at least one further functional unit, the earth working machine having a common power source, which provides both the energy for the work drive as well as the energy for the further functional unit. The common power source includes a common electrical supply switching device, to which every functional unit is connected in electrically conductive fashion, wherein the main functional unit includes an electric motor.

Claims

1-15. (canceled)

16. A self-propelled earth working machine, comprising: a machine frame; a plurality of wheels or tracks rollable on a ground surface for supporting the machine frame therefrom; a working apparatus supported from the machine frame; a common electrical supply switching device to which each of a first functional unit and at least one further functional unit are connected in electrically conductive fashion for transmitting electrical energy between the common electrical supply switching device and the first functional unit and the at least one further functional unit, wherein the first functional unit includes an electric motor for converting electrical energy transmitted to the first functional unit into kinetic energy to drive the working apparatus for earth working.

17. The self-propelled earth working machine of claim 16, wherein: the common electrical supply switching device includes a direct current intermediate circuit.

18. The self-propelled earth working machine of claim 16, further comprising: a power circuit interconnected between the common electrical supply switching device and the first functional unit and/or the at least one further functional unit, the power circuit being configured to change a magnitude of at least one parameter characterizing the electrical energy input by the common electrical supply switching device into the power circuit and to output the electrical energy thus modified to the first functional unit and/or the at least one further functional unit.

19. The self-propelled earth working machine of claim 18, wherein: the power circuit includes a DC voltage converter and/or an inverter.

20. The self-propelled earth working machine of claim 16, wherein: the at least one further functional unit includes a kinetic functional unit which converts the electrical energy supplied thereto into kinetic energy.

21. The self-propelled earth working machine of claim 16, wherein: the at least one further functional unit includes an operational functional unit which supplies the electrical energy supplied thereto to a static consumer.

22. The self-propelled earth working machine of claim 16, wherein the at least one further functional unit is selected from the group consisting of: a propulsion drive for driving the earth working machine to perform a driving movement on the ground surface; a ventilator drive for driving a ventilator situated on the earth working machine; a pump drive for driving at least one pump for conveying a fluid; a conveyor drive for driving a conveyor; an actuating drive for changing a relative position of a functional unit of the at least one further functional unit relative to the machine frame; a steering drive for changing a steering angle of at least one drive unit relative to the machine frame; a vehicle electrical system; an electrical illumination system of the earth working machine; an electrical signaling system of the earth working machine; and an electrical control device.

23. The self-propelled earth working machine of claim 22, wherein the at least one further functional unit comprises at least one pump drive, wherein an electric motor drives a plurality of pumps by interposition of a pump transfer gear.

24. The self-propelled earth working machine of claim 23, wherein at least one driven pump is a constant displacement pump, the output volume and/or delivery pressure of which is changeable by changing the rotational speed of the pump.

25. The self-propelled earth working machine of claim 22, wherein the at least one further functional unit comprises at least one pump drive, wherein an electric motor drives exactly one pump by interposition of a gear.

26. The self-propelled earth working machine of claim 25, wherein the pump is a constant displacement pump, the output volume and/or delivery pressure of which is changeable by changing the rotational speed of the pump.

27. The self-propelled earth working machine of claim 16, wherein a common power source comprising the common electrical supply switching device is configured to recuperate, during a deceleration of a kinetic functional unit as at least one of the first functional unit and the at least one further functional unit, connected in electrically conductive fashion to the supply switching device, kinetic energy of the kinetic functional unit as electrical energy.

28. The self-propelled earth working machine of claim 16, comprising a primary energy source which is connected in electrically conductive fashion to the common electrical supply switching device, the primary energy source comprising at least one of the following source units: an accumulator; a battery; a generator; a fuel cell system; a photovoltaic unit; a current collector; and a connection interface for connecting to an external current source.

29. The self-propelled earth working machine of claim 28, further comprising at least one secondary energy source which is connected in electrically conductive fashion to the common electrical supply switching device, the secondary energy source comprising at least one of the following source units: an accumulator; a battery; a generator; a fuel cell system; a photovoltaic unit; a current collector; and a connection interface for connecting to an external current source.

30. The self-propelled earth working machine of claim 29, wherein a supply circuit is interconnected between at least one energy source, of the primary energy source and the secondary energy source, and the common electrical supply switching device, and wherein the supply circuit is configured to change a magnitude of at least one parameter characterizing the electrical energy input by the at least one energy source into the supply circuit and to output the electrical energy thus modified to the common electrical supply switching device.

31. The self-propelled earth working machine of claim 30, wherein the supply circuit comprises at least one of a rectifier and a DC voltage converter.

32. The self-propelled earth working machine of claim 16, wherein the earth working machine has a combustion engine for operating an on-board generator, a power of the combustion engine not exceeding fifty percent (50%) of a nominal total operating power of the earth working machine.

33. The self-propelled earth working machine of claim 32, wherein the power of the combustion engine is configured not to exceed fifty percent (50%) of a nominal total operating power of the supply switching device.

34. The self-propelled earth working machine of claim 16, wherein the earth working machine is free of a combustion engine.

35. The self-propelled earth working machine of claim 16, wherein the working apparatus comprises a milling drum having a milling drum tube, wherein the electric motor of the first functional unit is at least partially surrounded by the milling drum tube, and wherein an axis of rotation of a rotor of the electric motor corresponds to an axle of the milling drum.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0057] The present invention will be explained in greater detail below with reference to the attached drawings. The figures show:

[0058] FIG. 1 a rough schematic side view of an earth working machine according to the invention in the exemplary form of a large road milling machine.

DETAILED DESCRIPTION

[0059] In FIG. 1, a specific embodiment according to the invention of an earth working machine in the form of an earth or road milling machine is generally indicated by reference numeral 10. It comprises a machine frame 12, which forms the basic framework for a machine body 14. Machine body 14 comprises machine frame 12 and the components of machine 10 which are connected to the machine frame and are, if indicated, movable relative thereto.

[0060] Machine body 14 comprises front lifting columns 16 and rear lifting columns 18, which are connected at one end to machine frame 12 and at the other end respectively to front drive units 20 and to rear drive units 22. The distance of machine frame 12 from drive units 20 and 22 is modifiable by way of lifting columns 16 and 18.

[0061] Drive units 20 and 22 are depicted by way of example as crawler track units. In a departure therefrom, individual, or all, drive units 20 and/or 22 may also be wheel drive units.

[0062] The viewer of FIG. 1 looks onto the earth working machine or simply “machine” 10 in a direction of view that is parallel to the transverse direction Q of the machine, which is orthogonal to the drawing plane of FIG. 1. A longitudinal machine direction orthogonal to transverse machine direction Q is labeled L and extends parallel to the drawing plane of FIG. 1. A vertical machine direction H likewise extends in parallel to the drawing plane of FIG. 1 and orthogonally to longitudinal machine direction L and transverse machine direction Q. The arrowhead of longitudinal machine direction L in FIG. 1 points in the forward direction. Vertical machine direction H extends in parallel to the yaw axis Gi of machine 10, longitudinal machine direction L extends in parallel to the roll axis Ro, and transverse machine direction Q extends in parallel to pitch axis Ni.

[0063] The earth working machine 10 may comprise an operator's platform 26, from which a machine operator is able to control machine 10 via a control panel 28 as a control device of the machine 10.

[0064] Arranged below machine frame 12 is a working assembly 30, here represented, by way of example, as a milling assembly 30 having a milling drum 34, accommodated in a milling drum housing 32, that is rotatable about a milling axis R extending in the transverse machine direction Q so that substrate material may be removed therewith during an earth working operation, starting from contact surface AO of the contact subsurface, or simply “subsurface” U, to a milling depth determined by the relative vertical position of machine frame 12. The milling drum 34 is therefore a working apparatus within the meaning of the present application. The contact subsurface U may also be referred to as ground surface U on which the wheels or tracks roll.

[0065] In the illustrated machine, the vertical adjustability of machine frame 12 by way of lifting columns 16 and 18 also serves to set the milling depth, or generally working depth, of machine 10 or the milling assembly 30 in the context of earth working. The earth working machine 10 depicted by way of example is a large milling machine, for which the placement of milling assembly 30 between and at a distance from the front and rear drive units 20 and 22 in the longitudinal machine direction L is typical. Large milling machines of this kind, or indeed earth-removing machines in general, usually comprise a transport device so that removed earth material can be transported away from machine 10. Of a transport device fundamentally present in machine 10, for reasons of better clarity, FIG. 1 only shows partially a discharge belt 36 with its end region located closer to the machine frame 12. The discharge belt 36 is loaded by a transfer belt, not shown in FIG. 1 but situated in region 38, with removed earth material, which the discharge belt 36 in the machine 10, designed as a front loader machine, transfers to a transport vehicle, driving ahead of the machine, which is likewise not illustrated in FIG. 1.

[0066] It is not apparent from the lateral view of FIG. 1 that machine 10 comprises, in both its front end region and its rear end region, two respective lifting columns 16 and 18 each having a drive unit 20, 22 connected to it. Front lifting columns 16 are respectively connected to drive units 20, in a manner also known per se, by a drive unit connecting structure 40, for example a connecting fork fitting around drive unit 20 in transverse machine direction Q. Rear lifting columns 18 are connected to their respective drive unit 22 via a rear drive unit connecting structure 42 constructed identically to the front drive unit connecting structure 40. Drive units 20 and 22 are of substantially identical construction and constitute traveling gear 24 of the machine. In the illustrated example, the drive units 20 and 22 are driven electromotively, namely, by one electric motor 44 per drive unit 20 and 22.

[0067] In the illustrated example, the drive unit 20, having a travel direction indicated by double arrow D, comprises a radially inner accommodation and guidance structure 46, which supports the electric motor associated with drive unit 20 and on which a circulating drive track 48 is arranged and is guided for circulating movement. The same applies analogously to drive unit 22.

[0068] Lifting column 16 and with it drive unit 20 are rotatable about a steering axis S1 by way of a steering apparatus (not illustrated further). Preferably additionally, but also alternatively, lifting column 18, and with it drive unit 22, may be rotatable by way of a steering apparatus about a steering axis S2 parallel to steering axis S1.

[0069] The machine comprises a power source 50, which represents a central energy supply of machine 10. At least, the power source 50 supplies multiple functional units of the machine 10 with energy, namely, directly with electrical energy.

[0070] The power source 50 comprises a supply switching device 52 accommodated on the machine frame 12. The supply switching device 52 is in the present case designed as a direct current intermediate circuit 52a.

[0071] In the illustrated exemplary embodiment, the supply switching device 52 receives electrical energy from a plurality of electrical energy sources. As an on-board energy source, for example as primary energy source 54, machine 10 carries along an accumulator 56, which supplies the supply switching device 52 with direct current. The rechargeable accumulator 56 is able to output the electrical energy stored within it directly to the supply switching device 52, since the output DC voltage of the accumulator 56 matches the operating DC voltage of the supply switching device 52. If this is not the case, a DC voltage converter may be situated between the accumulator 56 and the supply switching device 52.

[0072] In addition to the accumulator 56, the machine 10 has a plurality of secondary energy sources for the explanatory purposes. The division into primary and secondary energy sources is merely by way of example and may deviate from the presently illustrated example. Nevertheless, the assumption of a powerful accumulator 56 as primary energy source 54 of machine 10 is practical.

[0073] As a first secondary energy source, machine 10 and in particular the power source 50 may comprises a current collector 58, which taps alternating current from a current rail 60, which is supplied by a public power network PN fed by a power station K.

[0074] The current collector 58 is connected directly to a rectifier 62, which converts the tapped alternating current of the public power network into a DC voltage that is usable for the supply switching device 52. The rectifier 62 may be connected to a DC voltage converter 64, which converts the DC voltage output by the rectifier 62 to the DC voltage level of the supply switching device 52.

[0075] A further secondary energy source is a cable-bound plug connection 66, for example in the form of a plug socket, which may likewise be connected to the public power network PN via a matching counterpart 68, for example a plug. Since alternating current is thus obtained also via the plug connection 66, yet the supply switching device 52 requires DC voltage, the plug connection 66 is also connected to the rectifier 62 and to the DC voltage converter.

[0076] In order to provide the machine 10 with a sufficient range of movement in spite of the cable connection to the public power network PN, the cable connection of machine 10 to the public power network PN may be established via a cable winding drum vehicle 70, which accompanies the machine 10 in operation.

[0077] A further secondary energy source may be a photo-voltaic panel 72, which is situated for example on the outer side of the protective roof 26a of the operator's platform 26. Since such photo-voltaic panels 72 normally output a DC voltage, the photo-voltaic panel 72 is connected in electrically conductive fashion by interposition of a DC voltage converter 74 to the supply switching device 52.

[0078] In order to be able to generate electrical energy for operating the machine 10 autonomously, if necessary, the machine 10 includes a combustion engine 76 as a further secondary energy source, which is able to drive a generator 78 via its output shaft. The generator 78 is connected in electrically conductive fashion to the supply switching device 52 via a suitable power circuit, so that generator 78 supplies electrical energy to the supply switching device 52 in the appropriate form and at the appropriate voltage level.

[0079] The earth working machine 10 may also comprise a fuel cell system 79 as an alternative or additional secondary energy source, which supplies the electrical energy it generates to the supply switching device 52, if necessary, via a suitable power circuit.

[0080] On the output side, the supply switching device 52 provides DC voltage or direct current to a plurality of functional units. The main functional unit of the earth working machine 10 is an electric motor 80, which forms the rotary drive of the milling drum 34. A gear unit may be situated between the electric motor 80 and the milling drum 34. However, the electric motor 80 may also drive the milling drum 34 directly to perform the rotary motion. A power circuit 81, for example a DC voltage converter and/or an inverter, may also be situated between the supply switching device 52 and the electric motor 80, in order to bring the electrical energy output by the supply switching device 52 into a form of energy suitable for the electric motor 80 in terms of magnitude and/or form. Such a supply circuit may comprise a DC voltage converter and/or an inverter. For the present exemplary embodiment, however, the electric motor 80 shall be assumed to be a direct current motor suppliable directly by the supply switching device 52. Alternatively or additionally, the electric motor 80 may have an integrated power control, by which the motor power of the electric motor 80 may be changed in targeted fashion, for example by the use of control commands of the control panel 28.

[0081] Apart from the electric motor 80 as the main functional unit, the supply switching device 52 supplies numerous further functional units.

[0082] Thus, in the exemplary embodiment, by interconnection of an inverter 82, the supply switching device 52 supplies a synchronous motor 84, which directly drives a constant displacement pump 86 of a hydraulic circuit. The constant displacement pump 86, the output volume of which is directly controllable via its rotational speed, provides a pressure level in the hydraulic oil circuit, which allows for the operation of hydraulic power devices on machine 10, such as the lifting columns 16 and 18 for example.

[0083] As a further functional unit, the supply switching device 52 by interconnection of a DC voltage converter 88 supplies a direct current motor 90, which drives, by way of a pump transfer gear 92, a first pump 94 for conveying liquid cooling medium and a second pump 96 for conveying a further liquid medium, for example a refrigeration circuit medium of an air conditioning system.

[0084] A direct current ventilator motor 91 supplied directly with direct current by the supply switching device 52 drives a ventilator 93 in order to cool by convection at least one liquid medium, for example the refrigeration circuit medium, the cooling medium, the hydraulic oil or lubricating oil conveyed by a pump (not shown).

[0085] As further functional units, the supply switching device 52 furthermore supplies electrical direct current to an electric actuating drive 98 for adjusting the protective roof 26a of the operator's platform 26 between the operating position shown in FIG. 1 and a lowered stowage position, as well as to a front electric steering drive 100 and a rear electric steering drive 102. As further functional units, the supply switching device 52 likewise supplies direct current to an electric swivel drive 104 of the discharge belt 36 as a conveyor device of the machine 10 and the rotating drive 106 of the discharge belt for revolving motion of the belt.

[0086] Finally, the supply switching device 52 supplies direct current to the control panel 28 and to an illumination device 108 of the operator's platform 26. The illumination device 108 may be supplied with direct current by interconnection of a vehicle electrical system, so that the supply switching device 52 supplies a vehicle electrical system with a predetermined DC voltage, say, 24 V, for example after transforming the direct current using a DC voltage converter, the illumination device 108 or also the control panel 28 with its equipment for storing and processing data in turn being connected to the vehicle electrical system.

[0087] Thus, it is possible to operate the earth working machine 10 in fully electric fashion. In order to provide electrical energy at the earth working machine 10 as quickly as possible, the accumulator 56 may be connected to the supply switching device 52 by quick connectors that can be disconnected and reconnected quickly and may be connected to the machine frame 12 by quick-change fasteners that can be disconnected and reconnected quickly, so that a discharged accumulator, if sufficient time for charging it is not available, may be exchanged quickly for another, charged accumulator, if necessary.

[0088] The electric motors provided on the earth working machine 10 are capable of being operated as generators, so that in the event of decelerations at the devices driven by the respective electric motors, the kinetic energy reduced at the devices can be recuperated and be supplied to the accumulator 56 by the supply switching device 52 and be stored there.