Earth working machine having a shiftable transmission between a drive motor and a rotatable working apparatus

Abstract

An earth working machine (10), encompassing a drive motor (42) and a working apparatus (22) drivable by the drive motor (42) so as to move rotationally, the drive motor (42) being connected to the working apparatus (22), for transfer of a torque, with interposition of a shiftable transmission (50; 150) comprising at least two gearing stages having different torque transfer ratios, is characterized in that by means of a first gearing stage of the shiftable transmission (50), an input shaft (48), coupled on the input side to the drive motor (42), of the shiftable transmission (50) is connectable in torque-transferring fashion directly to an output shaft (52), coupled on the output side to the working apparatus (22), of the shiftable transmission (50) so as to rotate together at the same rotation speed; and by means of a second gearing stage of the shiftable transmission (50), the input shaft (48) is connectable in torque-transferring fashion, with interposition of a transmission assemblage (64), to the output shaft (52) so as to rotate together at different rotation speeds.

Claims

1. An earth working machine, comprising: a drive motor; a milling drum; a shiftable transmission connecting the drive motor to the milling drum for transfer of a torque to rotate the milling drum at a plurality of selectable transfer ratios, the shiftable transmission including an input shaft coupled to the drive motor and an output shaft coupled to the milling drum; and a braking apparatus disposed in a torque transfer path from and including the shiftable transmission to and including the milling drum, the braking apparatus being configured to bring the milling drum to a stop when the torque transfer path is interrupted; wherein the braking apparatus is arranged to act on the output shaft or another component of the shiftable transmission that always rotates together with the output shaft; and wherein the output shaft is coupled to the milling drum by a planetary gearset assemblage connected to the milling drum, and a belt drive connected between the shiftable transmission and the planetary gearset assemblage.

2. The earth working machine of claim 1, wherein: the braking apparatus includes a brake disc mounted on the output shaft.

3. The earth working machine of claim 1, further comprising: a plurality of power takeoffs configured such that all of the plurality of power takeoffs are always being rotationally driven when the input shaft is driven.

4. The earth working machine of claim 3, further comprising: a plurality of hydraulic pumps, each of the hydraulic pumps being coupled to one of the power takeoffs.

5. The earth working machine of claim 4, further comprising: a first power takeoff shaft defining two of the power takeoffs, two of the hydraulic pumps being coupled to the first power takeoff shaft.

6. The earth working machine of claim 5, further comprising: a second power takeoff shaft defining another two of the power takeoffs, another two of the hydraulic pumps being coupled to the second power takeoff shaft.

7. The earth working machine of claim 1, wherein: the transmission includes a clutch disposed between the input shaft and the output shaft.

8. The earth working machine of claim 1, wherein the transmission further includes: a first power takeoff shaft; a second power takeoff shaft; a first gear set whereby the input shaft drives the first power takeoff shaft; and a second gear set whereby the input shaft drives the second power takeoff shaft.

9. The earth working machine of claim 8, further comprising: a first pair of hydraulic pumps driven by the first power takeoff shaft.

10. The earth working machine of claim 9, further comprising: a second pair of hydraulic pumps driven by the second power takeoff shaft.

11. The earth working machine of claim 8, further comprising: a pinion gear attached to the input shaft, the pinion gear being a part of both the first gear set and the second gear set.

12. The earth working machine of claim 11, wherein: the transmission includes a clutch disposed between the pinion gear and the output shaft so that when the clutch is closed the pinion gear rotates with the output shaft, and so that when the clutch is open the pinion gear can drive the first and second power takeoff shafts without driving the output shaft.

13. An earth working machine, comprising: a drive motor; a milling drum; and a shiftable transmission connecting the drive motor to the milling drum for transfer of a torque to rotate the milling drum at a plurality of selectable transfer ratios, the shiftable transmission including: an input shaft coupled to the drive motor; an output shaft coupled to the milling drum; a first power takeoff shaft; a second power takeoff shaft; a first gear set whereby the input shaft drives the first power takeoff shaft; and a second gear set whereby the input shaft drives the second power takeoff shaft; wherein the output shaft is coupled to the milling drum by a planetary gearset assemblage connected to the milling drum, and a belt drive connected between the shiftable transmission and the planetary gearset assemblage.

14. The earth working machine of claim 13, further comprising: a first pair of hydraulic pumps driven by the first power takeoff shaft.

15. The earth working machine of claim 14, further comprising: a second pair of hydraulic pumps driven by the second power takeoff shaft.

16. The earth working machine of claim 13, further comprising: a pinion gear attached to the input shaft, the pinion gear being a part of both the first gear set and the second gear set.

17. The earth working machine of claim 16, wherein: the transmission includes a clutch disposed between the pinion gear and the output shaft, the clutch having a first engagement state in which the pinion gear rotates with the output shaft, and the clutch having a second engagement state in which the pinion gear can drive the first and second power takeoff shafts without driving the output shaft.

18. The earth working machine of claim 13, wherein: the first and second power takeoff shafts are always being rotationally driven when the input shaft is driven.

19. The earth working machine of claim 18, further comprising: a plurality of hydraulic pumps, each of the hydraulic pumps being coupled to one of the power takeoff shafts.

20. An earth working machine, comprising: a drive motor; a milling drum; a shiftable transmission connecting the drive motor to the milling drum for transfer of a torque to rotate the milling drum at a plurality of selectable transfer ratios, the shiftable transmission including: an input shaft coupled to the drive motor; an output shaft coupled to the milling drum; a first power takeoff shaft; a second power takeoff shaft; a first gear set whereby the input shaft drives the first power takeoff shaft; and a second gear set whereby the input shaft drives the second power takeoff shaft; and a first pair of hydraulic pumps driven by the first power takeoff shaft.

21. The earth working machine of claim 20, further comprising: a second pair of hydraulic pumps driven by the second power takeoff shaft.

22. An earth working machine, comprising: a drive motor; a milling drum; a shiftable transmission connecting the drive motor to the milling drum for transfer of a torque to rotate the milling drum at a plurality of selectable transfer ratios, the shiftable transmission including: an input shaft coupled to the drive motor; an output shaft coupled to the milling drum; a first power takeoff shaft; a second power takeoff shaft; a first gear set whereby the input shaft drives the first power takeoff shaft; and a second gear set whereby the input shaft drives the second power takeoff shaft; and a pinion gear attached to the input shaft, the pinion gear being a part of both the first gear set and the second gear set.

23. The earth working machine of claim 22, wherein: the transmission includes a clutch disposed between the pinion gear and the output shaft, the clutch having a first engagement state in which the pinion gear rotates with the output shaft, and the clutch having a second engagement state in which the pinion gear can drive the first and second power takeoff shafts without driving the output shaft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will be explained in further detail below with reference to the appended drawings, in which:

(2) FIG. 1 is an exemplifying view of an embodiment according to the present invention of an earth working machine of the present Application;

(3) FIG. 2 is a schematic block view of a drive train of the earth working machine of FIG. 1;

(4) FIG. 3 schematically depicts a first embodiment of the shiftable transmission from the drive train of FIG. 2; and

(5) FIG. 4 schematically depicts a second embodiment of the shiftable transmission from the drive train of FIG. 2.

DETAILED DESCRIPTION

(6) In FIG. 1, an earth working machine according to the present invention is labeled generally with the number 10. Earth working machine 10, embodied in the present example as a large road milling machine, stands on substrate U that is to be worked by it. The large road milling machine has for this purpose front 12 and rear 14 drive units that can be embodied as wheels or as crawler track units, which are known per se and will not be further discussed here.

(7) Large road milling machine 10 comprises an operator's platform 16 from which large road milling machine 10 can be controlled and operated.

(8) Located in the region behind operator's platform 16, i.e. between operator's platform 16 and the rear end of large road milling machine 10, is an engine compartment 18 in which is arranged an internal combustion engine 42 explained in further detail in conjunction with FIG. 2, which furnishes drive power for propelling and operating large road milling machine 10.

(9) Located in the region below operator's platform 16 and between the front and rear drive units 12 and 14 in a longitudinal machine direction is a milling drum housing 20 in which a milling drum 22 constituting a working apparatus, rotatable around a milling drum axis A orthogonal to the drawing plane of FIG. 1, i.e. the transverse direction of large road milling machine 10, is received.

(10) With milling drum 22, substrate U can be removed to a removal depth predetermined by modifying the height of machine frame 26 relative to drive units 12 and 14. Alternatively or additionally, milling drum 22 can be received in machine frame 26 vertically adjustably relative thereto. The milled material removed by milling drum 22 is wetted in milling drum housing 20 in order to decrease the environmental dust impact of large road milling machine 10, and conveyed by discharge device 24, indicated in FIG. 1 as being merely in the vicinity of the machine, in front of large road milling machine 10. During operation, large road milling machine 10 therefore usually follows a truck whose loading device it fills with bulk material while being operated to remove substrate U.

(11) Numerous apparatuses on large road milling machine 10, for example the vertical adjustment system for machine frame 26 relative to drive units 12 and 14, or the steering system for drive units 12 and 14 and the propulsion system for drive units 12 and 14, are implemented by way of hydraulic motors or hydraulic pumps. Milling drum 22, conversely, can be mechanically driven to move by way of internal combustion engine 42 received in engine compartment 18. Internal combustion engine 42 is a drive power source both for the mechanically driven milling drum 22 and for the hydraulically actuatable or drivable apparatuses of large road milling machine 10.

(12) In FIG. 2, the drive train of the working apparatus of earth working machine 10 of FIG. 1, in the form of a highly schematic block diagram, is labeled with the reference character 40. Drive train 40 encompasses internal combustion engine 42, for example in the form of a diesel internal combustion engine, as a source of drive power. The use of an Otto-cycle engine as a drive motor is, however, also not excluded. Drive shaft 44 of internal combustion engine 42 is coupled, with interposition of an elastic coupling 46 known per se, to input shaft 48 of a shiftable transmission 50 described in detail below in conjunction with FIG. 3.

(13) With the use of shiftable transmission 50 it is possible to operate the internal combustion engine at an optimum steady-state rotation speed and nevertheless to allow working apparatus 22, for example in the form of a milling drum or milling rotor, to operate at different rotation speeds and different torques. The steady-state operating rotation speed of internal combustion engine 42 can be selected for optimum performance, optimum emissions, and/or optimum consumption.

(14) An output shaft 52 of shiftable transmission 50 is coupled, via a belt drive 54 known per se, to the input side of a planetary gearset assemblage 56 that is connected on the output side to working apparatus 22 in torque-transferring fashion.

(15) Belt drive 54 comprises at least two belt pulleys, one of which can be embodied for temporary attachment of an auxiliary drive so that working apparatus 22 can be rotated at low speed for maintenance and/or repair purposes.

(16) As already noted above, what is depicted in FIG. 2 is merely a highly schematic block diagram. Planetary gearset assemblage 56 can in fact be arranged at least in part, or in fact entirely, in the interior of working apparatus 22.

(17) In the exemplifying embodiment depicted, working apparatus 22 encompasses a hollow cylindrical milling drum on whose outer side milling bits are arranged, usually with interposition of bit holders or quick-change bit holders. The cavity radially inside the milling drum and surrounded by it offers space to at least partly accommodate planetary gearset assemblage 56.

(18) As a rule, what takes place in drive train 40 is that the rotation speed of drive shaft 44 of internal combustion engine 42 is stepped down and the torque available at drive shaft 44 is stepped up. This means that working apparatus 22 rotates around its working apparatus axis more slowly than drive shaft 44 does around its rotation axis, but with a torque that, ignoring unavoidable losses, is reciprocally greater.

(19) Whereas, in the exemplifying embodiment presented, belt drive 54 steps torque down and rotation speed up from the input side to the output side, planetary gearset assemblage 56 steps torque up and steps speed down. In the example shown in FIG. 2, the planetary gearset assemblage is in fact the only one of the three rotation speed- and torque-converting apparatuses 50, 54, 56 which steps rotation speed down and steps torque up. In the present exemplifying embodiment, for example, the torque transfer ratio of the belt drive from the input side to the output side can be selected to be between 0.78 and 0.8, and in the present exemplifying embodiment the torque transfer ratio of planetary gearset assemblage 56 from the input side to the output side can be equal to approximately 20.5 to 20.7.

(20) Input shaft 48 of shiftable transmission 50 constitutes, more precisely, a principal input drive of shiftable transmission 50. Output shaft 52, depicted in FIG. 2, of shiftable transmission 50 likewise constitutes a principal output drive thereof.

(21) A first embodiment of shiftable transmission 50 is depicted highly schematically in FIG. 3.

(22) As depicted in FIG. 3, input shaft 48 and output shaft 52 of shiftable transmission 50 are selectably connectable to one another so as to rotate together at the same speed, or disconnectable from one another, by way of a direct-drive clutch 60. The direct-drive clutch can be, for example, a multi-disc clutch. By way of direct-drive clutch 60, input shaft 48 can be connected to output shaft 52 of the shiftable transmission to yield a shaft arrangement rotating together. Very high efficiency in terms of power transfer from internal combustion engine 42 to working apparatus 22 is thereby achieved.

(23) Direct-drive clutch 60 constitutes a first gearing stage for torque-transferring connection of input shaft 48 and output shaft 52. With this first gearing stage, no transmission assemblage of any kind is involved in the transfer of drive power from input shaft 48 to output shaft 52.

(24) A second gearing stage that can likewise be implemented on shiftable transmission 50 encompasses a transmission assemblage 64 that, upon activation of the second gearing stage and deactivation of the first gearing stage, transfers drive power from input shaft 48 to output shaft 52 of shiftable transmission 50.

(25) Transmission assemblage 64 encompasses a first transmission sub-assemblage 66 located closer to the input side, and a second transmission sub-assemblage 68 located closer to the output side, of shiftable transmission 50.

(26) In the exemplifying embodiment according to the present invention that is depicted, each of the two transmission sub-assemblages 66 and 68 encompasses exactly one gear pair.

(27) First transmission sub-assemblage 66 encompasses input drive pinion 70, which meshes with an output drive pinion 72 of the first transmission sub-assemblage. In the example depicted, output drive pinion 72 is arranged on an intermediate shaft 74 so as to rotate together.

(28) The tooth count of input drive pinion is assumed to be z.sub.1 and the tooth count of output drive pinion 72 is assumed to be z.sub.2; as shown in FIG. 3, z.sub.1>z.sub.2.

(29) Intermediate shaft 74 furthermore carries input drive pinion 76 of the second transmission sub-assemblage, which meshes with output drive pinion 78 of the second transmission sub-assemblage on output shaft 52.

(30) In the embodiment depicted, output drive pinion 78 is fixedly connected to output shaft 52 of shiftable transmission 50 so as to rotate together therewith at the same speed. In the example depicted, input drive pinion 76 of the second transmission sub-assemblage is selectably connectable to intermediate shaft 74 so as to rotate together, or disconnectable therefrom, via an intermediate clutch 80.

(31) Intermediate clutch 80 can again be a multi-disc clutch.

(32) In a departure from what is depicted in FIG. 3, intermediate shaft 74 can also be embodied as a split intermediate shaft, in which case input drive pinion 76 can then be fixedly coupled to the output drive side of intermediate shaft 74, and the input drive side and output drive side of the (now split) intermediate shaft can be connectable to one another in order to rotate together, or disconnectable from one another, by way of intermediate clutch 80.

(33) Input drive pinion 76 of the second transmission sub-assemblage has a tooth count z.sub.3 that is greater than the tooth count z.sub.4 of output drive pinion 78 of second transmission sub-assemblage 68.

(34) The tooth counts z.sub.1, z.sub.2, z.sub.3, and z.sub.4 are selected so that the tooth counts of pinions of similar size, i.e. for example the tooth counts z.sub.1 and z.sub.3 of the two input drive pinions 70 and 76, likewise differ from one another by no more than two teeth, as also do the tooth counts z.sub.2 and z.sub.4 of the similarly sized output drive pinions 72 and 78. It is then the case that the transfer ratios of the two transmission sub-assemblages 66 and 68 can differ by no more than 1%, so that for an assumed overall transfer ratio j of transmission assemblage 64, it is approximately true that each transfer ratio of transmission sub-assemblages 66 and 68 is approximately the square root of j. The result is that at the meshing engagement points of the respective transmission sub-assemblages, i.e. between pinions 70 and 72 on the one hand and between pinions 76 and 78 on the other hand, the forces that are transferred between the pinions are approximately the same, which results in homogeneous loading of the two transmission sub-assemblages and thus uniform wear behavior for the entire transmission assemblage 64.

(35) With the arrangement of direct-drive clutch 60 and intermediate clutch 80 as shown, shiftable transmission 50 can advantageously be shifted between its two gearing stages under load. It is therefore possible to switch, with no interruption in load, between direct drive and the transfer ratio furnished by transmission assemblage 64.

(36) For reliable stoppage of the working apparatus when both clutches (direct-drive clutch 60 and intermediate clutch 80) are released, shiftable transmission 50 preferably comprises a braking apparatus 81 that, in the present embodiment, interacts with the output drive side of intermediate clutch 80. A brake disc 81a, on which braking force can be exerted by a brake caliper 81b of braking apparatus 81, can be provided for this purpose on the output drive side of intermediate clutch 80.

(37) Merely for the sake of completeness, be it noted that shiftable transmission 50 comprises four further power takeoffs 82, 84, 86, 88.

(38) Hydraulic pumps 90, 92, 94, 96 are respectively coupled to power takeoffs 82, 84, 86, 88. Shiftable transmission 50 is thus, in the present case, a pump distributor transmission.

(39) In the example depicted, power takeoffs 82 and 84 are located on a common first power takeoff shaft 85. Power takeoffs 86 and 88 are located on a common second power takeoff shaft 87.

(40) First power takeoff shaft 85 is rotationally driven by a power takeoff pinion 89 that is connected to first power takeoff shaft 85 so as to rotate together, and meshes permanently with input drive pinion 70 of first transmission sub-assemblage 66.

(41) Second power takeoff shaft 87 also has a second power takeoff pinion 91 connected nonrotatably to it so as to rotate together. Said pinion is rotationally driven indirectly, with interposition of an intermediate pinion 93, by output drive pinion 72 of first transmission sub-assemblage 66. This ensures that first and second power takeoff shafts 85 and 87 rotate in the same direction. It also ensures that, regardless of the engagement states of direct-drive clutch 60 and intermediate clutch 80, torque is always transferred both to first power takeoff shaft 85 and to second power takeoff shaft 87.

(42) A control apparatus of shiftable transmission 50 ensures exclusion of critical operating states, for example simultaneous torque transfer engagement of both direct-drive clutch 60 and intermediate clutch 80, or braking engagement of braking apparatus 81 when direct-drive clutch 60 and intermediate clutch 80 are not both released. The control apparatus of shiftable transmission 50 can be implemented by a machine control apparatus of earth working machine 10, or can be a control apparatus separate therefrom, for example using respective microprocessors and/or stored-program control systems as known in the existing art.

(43) In a departure from what is depicted in FIG. 3, a part of intermediate shaft 74 which is constantly rotationally driven by the input shaft can also be guided out of a housing of shiftable transmission 50 as an additional or alternative power takeoff.

(44) Only one of the two clutches (direct-drive clutch 60 and intermediate clutch 80) can be respectively activated for torque transfer, while the other must be deactivated. It is possible, however, to deactivate both clutches 60 and 80 simultaneously, for example if torque is required only at the power takeoffs but not at the principal output drive.

(45) FIG. 4 depicts a second embodiment of a shiftable transmission according to the present invention. Identical and functionally identical components and component portions are labeled in FIG. 4 with the same reference characters as in FIG. 3, but incremented by 100. The second embodiment in FIG. 4 will be described below only to the extent that it differs from the first embodiment in FIG. 3, the description of which is otherwise also to be referred to for an explanation of the second embodiment in FIG. 4.

(46) Shiftable transmission 150 of FIG. 4 comprises no power takeoffs, but only the principal input drive through input shaft 148 and principal output drive via output shaft 152.

(47) Intermediate clutch 180 in FIG. 4 is also, merely as an illustration of design options, arranged not on intermediate shaft 174 but on output shaft 152. Intermediate clutch 180 serves to selectably connect output drive pinion 178 of second transmission sub-assemblage 164 to output shaft 152 or disconnect it therefrom.

(48) Even though intermediate clutch 180 is arranged on output shaft 152 of shiftable transmission 150, it is an intermediate clutch 180 for purposes of the present Application because it is arranged in the torque transfer path of transmission arrangement 168 and enables interruption or establishment of a transfer of torque from input shaft 148 to output shaft 152 via intermediate shaft 174.

(49) In this second embodiment, braking apparatus 181 interacts with output shaft 152, which supports a brake disc 181 so as to rotate together with it.