Earth working machine

Abstract

An earth working machine (10), in particular a road milling machine, a stabilizer, or the like, having a milling drum (30) that is mounted rotatably on a machine frame (11) and is populated or populatable on its outer circumference with working tools (31); the working tools (31) to come into contact, during working operation, with the ground that is to be worked to remove it; a drive unit (20) drives the milling drum (30) by means of a drive motor (21); an input drive shaft (33) couplable to the drive motor (21) is attached to the milling drum (30); and a ballast element, constituting a kinetic mass (57), increases the kinetic energy of the milling drum (30). The kinetic mass (57) is couplable to or decouplable from the rotatable milling drum (30), or a rotational member indirectly or directly coupled to the milling drum (30), via a shiftable coupling (55).

Claims

1. An earth working machine, comprising: a machine frame; a working drum rotatably mounted relative to the machine frame, the working drum including working tools configured to contact a ground surface to work the ground surface; a drive motor; an input drive shaft connected to the working drum, the input drive shaft being configured to be coupled to the drive motor so that the drive motor drives the working drum; a kinetic mass; and a shiftable coupling configured to couple the kinetic mass to the working drum to increase a kinetic energy of the working drum and to decouple the kinetic mass from the working drum.

2. The earth working machine of claim 1, wherein: the working drum rotates at a speed in a range of from 30 to 240 revolutions per minute; and the kinetic mass rotates at a speed in a range of from 60 to 4000 revolutions per minute.

3. The earth working machine of claim 1, wherein: the working drum has a moment of inertia having a first value when the shiftable coupling is disengaged to decouple the kinetic mass from the working drum, and the working drum and the kinetic mass together have a moment of inertia having a second value when the shiftable coupling is engaged to couple the kinetic mass to the working drum, the second value being at least twice as great as the first value.

4. The earth working machine of claim 1, wherein: a moment of inertia of the kinetic mass is greater than or equal to T/i.sup.2, where T corresponds to a moment of inertia of the working drum and i is a rotation speed ratio between a rotation speed of the kinetic mass and a rotation speed of the working drum.

5. The earth working machine of claim 1, further comprising: a conversion transmission connected between the kinetic mass and the working drum, the conversion transmission being configured to convert a rotation speed of the working drum to a higher rotation speed of the kinetic mass, the conversion transmission having a conversion ratio modifiable in at least two ratio steps or steplessly.

6. The earth working machine of claim 1, further comprising: a conversion transmission connected between the kinetic mass and the working drum, the conversion transmission being configured to convert a rotation speed of the working drum to a higher rotation speed of the kinetic mass; and wherein the working drum encloses an installation space, and the conversion transmission is located at least partially in the installation space.

7. The earth working machine of claim 1, further comprising: a conversion transmission connected between the kinetic mass and the working drum, the conversion transmission being configured to convert a rotation speed of the working drum to a higher rotation speed of the kinetic mass; a working drum housing attached to the machine frame; and wherein the conversion transmission is located at least partially inside the working drum housing.

8. The earth working machine of claim 1, wherein: when the shiftable coupling is engaged the working drum is coupled to the kinetic mass such that a rotation speed of the working drum and a rotation speed of the kinetic mass are equal to one another, slippage of the shiftable coupling being disregarded.

9. The earth working machine of claim 1, wherein: wherein the working drum encloses an installation space; and the shiftable coupling and the kinetic mass are arranged inside the installation space surrounded by the working drum.

10. The earth working machine of claim 1, wherein: the kinetic mass is exchangeable.

11. The earth working machine of claim 1, further comprising: a bearing shaft disposed on an opposite end of the working drum from the input drive shaft, the working drum being rotatably mounted relative to the machine frame on the bearing shaft; wherein the shiftable coupling is connected to one of the input drive shaft and the bearing shaft.

12. The earth working machine of claim 1, further comprising: a conversion transmission connected between the kinetic mass and the working drum, the conversion transmission being configured to convert a rotation speed of the working drum to a higher rotation speed of the kinetic mass.

13. The earth working machine of claim 12, further comprising: a bearing shaft disposed on an opposite end of the working drum from the input drive shaft, the working drum being rotatably mounted relative to the machine frame on the bearing shaft; and wherein the conversion transmission includes an input drive side connected to one of the input drive shaft and the bearing shaft.

14. The earth working machine of claim 13, wherein: the conversion transmission includes an output drive side, and the shiftable coupling is connected between the output drive side of the conversion transmission and the kinetic mass.

15. The earth working machine of claim 1, further comprising: a conversion transmission connected between the kinetic mass and the working drum, the conversion transmission being configured to convert a rotation speed of the working drum to a higher rotation speed of the kinetic mass; a working drum housing attached to the machine frame, the working drum housing defining an internal space, the working drum being received at least partially in the internal space of the working drum housing; and wherein the conversion transmission is arranged on the working drum housing outside of the internal space.

16. The earth working machine of claim 15, wherein: the conversion transmission is mounted on a side wall of the working drum housing.

17. The earth working machine of claim 1, wherein: when the shiftable coupling is engaged the working drum is coupled to the kinetic mass such that a rotation speed of the working drum and a rotation speed of the kinetic mass deviate from one another.

18. The earth working machine of claim 17, further comprising: a conversion transmission connected between the working drum and the kinetic mass, the conversion transmission providing the deviation between the rotation speed of the working drum and the rotation speed of the kinetic mass.

19. The earth working machine of claim 1, further comprising: a milling transmission; wherein the working drum encloses an installation space, and the milling transmission is located at least partially in the installation space; and wherein the input drive shaft is received in the milling transmission.

20. The earth working machine of claim 19, wherein: the milling transmission comprises a planetary transmission including a sun gear on a sun gear shaft; and the shiftable coupling is configured to couple the kinetic mass to the sun gear shaft.

21. The earth working machine of claim 1, further comprising: an endlessly circulating belt drive connecting the drive motor to the input drive shaft.

22. The earth working machine of claim 21, further comprising: a pump distribution transmission driven by the drive motor and located between the drive motor and the endlessly circulating belt drive.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

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

(2) FIG. 1 is a side view of a large milling machine constituting an example of an earth working machine;

(3) FIG. 2 schematically depicts a milling unit of the earth working machine according to FIG. 1;

(4) FIG. 3 schematically depicts a milling drum housing having a milling drum received therein; and

(5) FIG. 4 schematically depicts a milling drum housing having a milling drum received therein, as an alternative to the embodiment in accordance with FIG. 3.

DETAILED DESCRIPTION

(6) FIG. 1 shows, as an earth working machine, a road milling machine 10 for milling road surfaces made of asphalt, concrete, or the like. Road milling machine 10 comprises a machine frame 11 having an operator's platform 12. On operator's platform 12, the machine operator can drive the road milling machine and can control functions of the road milling machine.

(7) Machine frame 11 is carried by a propelling unit 13. Propelling unit 13 encompasses, for example, four crawler track units 14 that are arranged at the front and rear end on both sides of machine frame 11. Crawler track units 14 enable the road milling machine to move forward and backward along a travel path. Lifting columns 15 are provided in order to adjust the height of machine frame 11 with respect to propelling unit 13. Crawler drive units 14 on the one hand, and machine frame 11 on the other hand, are fastened onto these lifting columns 15. By adjusting lifting columns 15, the machine operator can perform a vertical alignment of machine frame 11 with respect to a roadway.

(8) Wheels can also be provided instead of a crawler track unit 14.

(9) The road milling machine possesses a working unit, which is a milling device having a milling drum 30. Milling drum 30 is populated with working tools 31. The milling drum 30 may also be referred to as a working drum 30.

(10) Working tools 31 are fastened replaceably on milling drum 30 through the intermediary of retaining arrangements, for example bit holders or quick-change bit holder systems.

(11) As FIG. 1 shows, milling drum 30 is arranged on machine frame 11 between the front and rear crawler track units 14. The invention is of course not limited to utilization in the context of such types of machine, usually referred to as “large” milling machines. It is instead also conceivable for milling drum 30 to be arranged between the rear propelling units. Such machine types are usually referred to as “compact” or “small” milling machines. The roadway surface is milled off with milling drum 30. In order to drive milling drum 30, the road milling machine comprises a drive unit 20 that is also carried by machine frame 11. Drive unit 20 is depicted schematically, and drawn with dashed lines, in FIG. 1.

(12) Drive unit 20 drives not only milling drum 30 but also crawler track units 14 and further units of the road milling machine, which include e.g. lifting columns 15 for adjusting machine frame 11, or positioning drives (not depicted) for steering, or a water pump (not depicted) for cooling working tools 31 of milling drum 30.

(13) FIG. 2 schematically depicts drive unit 20. This drawing once again shows milling drum 30, specifically in a view from the left transversely to the direction of travel, perpendicularly to the image plane in accordance with FIG. 1. Working tools 31 are depicted schematically in this view. As the illustration further shows, milling drum 30 is arranged in a milling drum housing 40. Milling drum housing 40 possesses side walls 41 and a top panel 42. Side walls 41 and top panel 42 shield milling drum 30 with respect to the environment. An opening is usually provided on milling drum housing 40, through which material can travel onto a conveying apparatus (not depicted), for example made up of conveyor belts, in order to load the material, for instance, onto a truck.

(14) Milling drum 30 is mounted rotatably on machine frame 11 or on milling drum housing 40. Milling drum 30 possesses an input drive shaft 33 and a bearing shaft 32.

(15) Milling drum 30 can be driven with drive unit 20. Specifically, drive unit 20 encompasses a drive motor 21 that is usually constituted by an internal combustion engine. Drive motor 21 is connected via a coupling element 22 to a pump distribution transmission 23. For a space-saving design, coupling element 22 can be arranged at least locally in a cavity 24 of the pump distribution transmission. In the pump distribution transmission, a fluid becomes pressurized. That fluid is guided via pressure conduits to individual functional units of the road milling machine, for example lifting columns 15, or to hydraulic motors of crawler track unit 14. A shifting device 25 is provided downstream from pump distribution transmission 23.

(16) Drive motor 21 can be selectably coupled to or decoupled from a shaft 26 by means of shifting device 25.

(17) Shaft 26 carries a belt pulley 27 that is part of a transfer unit 28. Transfer unit 28 also encompasses a further belt pulley 29. The two belt pulleys 27, 29 are connected to one another by an endlessly circulating belt drive.

(18) As FIG. 2 illustrates, belt pulley 29 is retained on input drive shaft 33 of the milling drum. Input drive shaft 33 is guided through a lateral opening in the associated side wall 41 of milling drum housing 40. Input drive shaft 33 is coupled indirectly or directly onto milling drum 30. A bearing shaft 32 is provided concentrically with input drive shaft 33 on the oppositely located side of milling drum 30. Input drive shaft 33 and bearing shaft 32 together form the rotation axis for milling drum 30.

(19) FIG. 2 further illustrates the fact that a conversion transmission 50 is arranged outside the milling drum housing. This conversion transmission 50 can be designed as a transmission having one or several transmission ratio steps, or as a steplessly operating transmission. Bearing shaft 32 leads directly to the input side of conversion transmission 50. A connecting piece 54 in the form of a shaft, constituting a rotational member, is arranged on the output drive side of conversion transmission 50. Connecting piece 54 creates the connection to a coupling 55, which here is a shiftable coupling 55. Shiftable coupling 55 can be operated from operator's platform 12. It is also conceivable for a separately actuatable shifting unit, for operating coupling 55, to be provided in the vicinity of milling drum housing 40. Preferably, however, shiftable coupling 55 is to be operated from operator's platform 12, offering considerably simplified operation.

(20) Coupling 55 is connected via a supporting shaft 56 to a kinetic mass 57. Kinetic mass 57 is a weight that is attached to supporting shaft 56. It is also conceivable for kinetic mass 57 to be exchangeably coupled, indirectly or directly, to supporting shaft 56.

(21) The configuration depicted in FIG. 2 is illustrated once again in more detailed fashion in FIG. 3, the view selected here being one in which milling drum 32 is depicted from the opposite side.

(22) As FIG. 3 shows, conversion transmission 50 is fastened externally onto the associated side wall 41.

(23) Conversion transmission 50 can be embodied, for example, as a planetary transmission, a driving element 51, which constitutes the sun gear of the planetary transmission, being retained on bearing shaft 32. In addition, a planet carrier 52 having an output drive element 53 (planet gears) is retained nonrotatably on connecting piece 54. As FIG. 3 illustrates, planet carrier 52 carries gears that mesh with the sun gear. The invention is, of course, not limited to the use of a planetary transmission as conversion transmission 50. It is instead also conceivable for other forms of transmission to be used.

(24) The manner of operation of the arrangement shown in FIGS. 2 and 3 is as follows: Drive motor 21 drives pump distributor transmission 23 via coupling element 22. When shifting device 25 is engaged, shaft 26 is connected to drive motor 21. Transfer unit 28 is thereby driven at a rotation speed n2 that can correspond to rotation speed n1 of drive motor 21. On the output drive side of transfer unit 28, rotation speed n2 is present at input drive shaft 33. In large milling machines, rotation speed n1 corresponds approximately to rotation speed n2, although a different conversion ratio can of course also be selected. That rotation speed n2 is then stepped down, by means of a milling transmission (not depicted in the drawing), to a lower rotation speed n3 at which milling drum 30 rotates. In ordinary road milling machines, this conversion ratio between the higher rotation speed n2 and the milling drum rotation speed n3 is in the range between 10 and 30.

(25) The same rotation speed n3 at which milling drum 30 is rotating is also present at bearing shaft 32. Rotation speed n3 accordingly also feeds into the input drive side of conversion transmission 50, as shown in FIG. 3.

(26) Conversion transmission 50 then converts rotation speed n3 to a higher rotation speed n4 that is present at connecting piece 54. When coupling 55 is closed, this rotation speed n4 is also present at supporting shaft 56, so that kinetic mass 57 rotates at the higher rotation speed n4.

(27) When coupling 55 is closed, kinetic mass 57 can consequently be coupled to milling drum 30 via coupling 55 and conversion transmission 50. The rotational energy generated during the rotary motion of kinetic mass 57 is introduced into milling drum 30, thereby increasing the kinetic energy of milling drum 30. The result is that milling drum 30 runs more smoothly.

(28) FIG. 4 depicts an alternative variant embodiment of the invention. As this drawing illustrates, milling drum 30 is once again accommodated in milling drum housing 40. Input drive shaft 33 and bearing shaft 32 are once again coupled rotatably onto machine frame 11 or onto milling drum housing 40. A milling transmission 60 is accommodated in the space surrounded by milling drum 30. As has been explained above, rotation speed n2 of belt pulley 29 can be stepped down by this milling transmission 60. Milling transmission 60 can be embodied as a planetary transmission. It possesses a driving element 61, usually a gear, that is nonrotatably connected to input drive shaft 33. One or several gears 62 (planet gears) mesh with this driving element 61 in order to achieve a stepdown in rotation speed. This stepped-down rotation speed then corresponds to rotation speed n3 of milling drum 30. Input drive shaft 33 has a connecting piece 63 that is attached via a coupling 55 to a supporting shaft 56. Supporting shaft 56 carries kinetic mass 57. Rotation speed n4 at which kinetic mass 57 rotates accordingly corresponds to rotation speed n2 of input drive shaft 33 when coupling 55 is closed. It is also conceivable to provide a conversion transmission 50 that is arranged before or after coupling 55 and that steps rotation speed n2 of drive shaft 33 up to a higher rotation speed n4 at which kinetic mass 57 rotates.

(29) As is evident from FIG. 4, kinetic mass 57 and coupling 55 are arranged in protected fashion inside the installation space surrounded by milling drum 30. Milling transmission 60 is also arranged locally inside milling drum housing 40, and partly inside the installation space surrounded by milling drum 30.

(30) In the exemplifying embodiments described above, the axis around which kinetic mass 57 rotates aligns with the rotation axis of milling drum 30. It is also conceivable, however, for these two rotation axes to be arranged parallel to one another at a distance. It is furthermore conceivable for these rotation axes to proceed at an angle to one another.