Patent Application
20110266858
The present invention relates to an apparatus for processing ground surfaces.
Such automotive construction machines for processing surfaces are known from EP 1 408 158 B1.
The road milling machine which is described therein comprises a machine frame with a drive motor for driving moving devices and for driving working devices. The moving devices can consist of wheels or track assemblies which are connected with the machine frame via lifting columns.
As a roller drive, the drive device especially drives a milling drum for milling ground surfaces, preferably in counter-rotating operation. The milling drum can be uncoupled from the drive train by means of a coupling device. A scraper blade is disposed in a height-adjustable manner in the direction of travel behind the milling drum, which scraper blade slides over the surface that has been milled or is to be milled by the milling drum. The bottom edge of the scraper blade is always disposed at the lowest plane of the cutting circle of the milling drum in milling operation.
Such construction machines work in a strip-like manner according to the width of the milling drum. This means that, after completion of a predetermined section of milled ground surface, the construction machine needs to travel back in order to mill off an adjacent strip. This reverse travelling is known as maneuvering operation. In maneuvering operation, the working device is in the so-called maneuvering position, while it is in the so-called working position in working operation.
What is relevant here is that, in contrast to working operation, the milling drum has the same rotational direction in maneuvering operation as the moving devices. This is also known as synchronized operation.
In order to prevent any inadvertent collision of the tools of the milling drum with the ground surface in synchronized operation, it is necessary according to the state of the art that the milling drum stands still during reverse travel because the construction machine can be accelerated in an uncontrolled and sudden manner in case of an inadvertent engagement of the milling drum with the ground surface. Since the circumferential speed of the milling drum, especially at operating speed, can be many times, e.g., three times, the travelling speed, a strong and uncontrolled acceleration of the road construction machine can occur in case of a sudden engagement of the milling drum. Moreover, there is a danger that the milling drum will be damaged in the event of an inadvertent engagement with the ground surface.
According to the aforementioned EP 1 408 158 B1, the milling drum is decoupled from the drive train after it has been moved upward from the milling cut at the end of a strip of ground surface to be processed. The construction machine can now be moved back without any danger in maneuvering operation to the beginning of the section to be processed, wherein the drive motor at first needs to be throttled to idle speed for the renewed coupling of the milling drum. Both the lowering of the drive motor, which consists of an internal combustion engine, to idle speed and also the renewed acceleration to operating speed requires a considerable waiting period, unlike a conventional passenger car engine.
Before processing the next strip, the drive motor needs to be brought back again to operating speed. These processes are very time-consuming and very onerous for the vehicle operator, especially in cases where short sections are to be processed. Moreover, the continual engagement of the clutch and the resulting frequent load changes of the engine lead to increased wear and tear on the coupling device, the engine and all components involved in the drive train.
An automotive construction machine developed for remedying these disadvantages and a method for processing ground surfaces is known from DE 10 2006 024 123 A1.
The road milling machine described therein provides that the milling drum can be removed from the milling cut by pivoting or lifting by means of lifting columns of the moving devices. The distance of the lifted milling drum from the ground surface is monitored by a monitoring device. If this monitoring device detects a shortfall in a predetermined distance, either the lifted milling drum which continues to rotate at this point is decoupled from the drive motor or the moving devices are decoupled from the drive motor, the machine frame is lifted or an alarm signal is generated. If the milling drum actually has ground contact, it is merely necessary to destroy the current rotational energy. The mass of the construction machine is sufficient in order to prevent a jump of the construction machine in the direction of travel.
In such a construction machine, the milling drum can remain coupled with the drive motor permanently, in particular in a synchronous maneuvering operation. The time lost when making the necessary adjustments, e.g., by throttling and accelerating the drive motor, is reduced to a considerable extent.
Such a monitoring device, however, does not offer any guarantee for a reliable and flawless monitoring with respect to the detection of the distance of the rotating, lifted milling drum from the ground surface. There is a danger, for example in case of flaws in the ground surface or suddenly rising or falling ground surfaces, that a secure reaction of the monitoring device does not occur or only occurs too late. This can have serious consequences because the rotating milling drum might engage the ground surface and accelerate the construction machine in a sudden and uncontrolled manner.
The invention is therefore based on the object of providing an apparatus for processing ground surfaces, with which the processing of ground surfaces can be reliably streamlined and with which in particular the time required for changing between a working operation and a maneuvering operation can be shortened and corresponding waiting periods reduced.
According to one embodiment of the present invention, an apparatus for processing ground surfaces comprises a moving device, a working device and especially a milling device for milling the ground surface, and a drive device for driving the moving device and the working device which can be moved to a working position, in which it is in operative engagement with the ground surface, and to a maneuvering position, in which it is not in operative engagement with the ground surface, wherein a sensor device is provided which detects the maneuvering position and/or at least one working parameter of the working device, namely its power consumption, working speed, rotational speed or its inclination, and/or at least one load parameter of the moving device, and a control device which reduces the frictional connection between the drive device and the working device and/or the drive power transmitted by the drive device to the working device in the maneuvering position and/or in case of detection of a deviation of the at least one detected working parameter or load parameter from a set parameter value.
Preferably, the working device comprises at least one milling device for milling the ground surface, wherein the term milling device means any tools and devices for processing the ground surface such as grinding, compacting, milling or leveling tools. In relation to the rotational direction of the milling device, the moving device preferably has the same direction of rotation in maneuvering operation and an opposite direction of rotation in working operation.
It is principally possible in the apparatus in accordance with the present invention to adapt the drive device as one drive or a plurality of drives. Accordingly, the working devices and the moving devices can be driven either by a common drive or also by their own drives. This will be described below in greater detail.
One aspect of the invention is that, inter alia, the working device can remain permanently coupled with the drive device, i.e. in working operation as well as in maneuvering operation, by the use of the above sensors specific in particular to the working parameters.
The control device is adapted so as to monitor the frictional connection at work between the drive device and the working device and reduce such frictional connection when a maneuvering operation and/or a deviation of a detected parameter from a set parameter is determined. These detected parameters are working parameters of the working device or the entire apparatus, namely their power consumption, working speed, rotational speed or inclination, and/or load parameter of the moving device or apparatus, such as the weight acting on the moving device or acceleration.
It is possible, for example, to reduce the drive power transferred to the drive device during the detection of the maneuvering operation via the control device in such a way that, in case of malfunction, i.e. the unintended contact of the drive device with the ground surface, it is merely necessary to brake the machine's reduced drive power. Although the drive device in this state is still operating at a (reduced) working speed from which working operation can be resumed quickly again after maneuvering, this speed is no longer sufficient to accelerate the machine in an uncontrolled manner in case of a sudden inadvertent engagement.
Furthermore, unintended action of the drive device on the apparatus, e.g., in the case of an unintended contact of the working device with the ground surface during maneuvering operation, can be prevented by a selective controlling of the frictional connection between the drive device and the working device; in particular the safety of processing ground surfaces can thus be improved with such an apparatus. A frictional connection can thus be reduced in such a way that although the drive device is further driven in the maneuvering position at a set speed, preferably the working speed, a frictional connection threshold is exceeded upon contact with the ground surface so that no further drive power that can drive the apparatus in an uncontrolled manner is transmitted.
In contrast to the detection of the distance between the working device and the ground surface and the reaction to the detection of a shortfall in this distance, the apparatus in accordance with the present invention offers a much more precise and secure possibility for checking whether or not there is a trouble-free maneuvering operation. In particular the detection of the working parameters acting on the apparatus, especially the working device, is an essential aspect here. Thus, e.g., the speed of the working device can be detected by using corresponding sensors. Since the rotational speed will change suddenly upon a sudden engagement of the working device with the ground surface or any other impediment, a malfunction can thus be inferred directly and effectively. The same applies to the monitoring of the required drive power, the consumption of which will also rise suddenly in case of a malfunction as described above. The same applies to a change in inclination of the working device or the apparatus itself.
In accordance with the present invention, the tedious deactivation of the drive train of the working device and, in turn, the tedious reactivation of the subsequent working operation are no longer necessary when initiating the maneuvering operation. This allows the operator to execute the tasks to be performed with the apparatus much more efficiently.
As already explained above, the working device and especially the milling device of the apparatus are preferably in operative connection with a drive device via a coupling device. The control device controls the frictional connection and/or the slip (clutch slip) of this coupling device. This way, the working device is still driven especially in maneuvering operation, while the reduced frictional connection ensures that no acceleration of the apparatus is initiated via its drive in case of inadvertent contact of the working device with the ground surface.
The frictional connection and especially the clutch slip of the clutch device are adjustable in such a way that there is essentially no clutch slip in maneuvering operation while there is clutch slip in working operation. This can preferably be set individually for any apparatus, any drive device and for further ambient parameters, for example the working speed, the type of ground surface to be processed, etc.
The apparatus is further characterized in that the sensor device of the apparatus preferably comprises at least one load sensor which is in operative connection with the moving device. This detects the load parameters acting on the moving device such as weight loads, acceleration loads and/or changes in the latter. Accordingly, any unexpected change in force or alleviation not initiated by the operator and caused by an unintentional engagement of the drive device with the ground surface or any other impediment can be identified. In response, the frictional connection between the drive device and the working device and/or the drive power transmitted to the drive device can be reduced rapidly and effectively or corresponding safeguards taken.
Preferably, the sensor device of the apparatus comprises at least one inclination sensor which detects an inclination and/or a change in inclination of the apparatus. An unplanned engagement of the drive device or a similar disturbance which inevitably leads to an especially abrupt change in the inclination of the apparatus can thus be detected quickly and reliably.
The sensor device preferably comprises at least one workload sensor which detects the power consumption and/or the working speed and/or the rotational speed of the working device and/or changes in the latter. This way, the frictional connection or the drive power between the drive device and the working device can be reduced or corresponding safeguards taken in case of deviations of one of these parameters from a set parameter value.
In one embodiment, this workload sensor is in operative connection with the coupling device. Accordingly, the drive power, the drive speed, the coupling slip and/or changes in the latter can be detected for the coupling device and one of the above “safeguards” can be taken in case of a deviation of one of these parameters from a set parameter value.
A further advantage of the sensors and monitoring device described above is the possibility of monitoring the machine also in terms of its operability, especially in normal working operation. Disturbances in operation, which can be inferred from e.g. defective clutch elements, worn-out tools etc., can thus be detected with the same sensors in a secure and cost-effective way.
In a further embodiment, the drive device preferably comprises an auxiliary drive device and a main drive device. The working device is or can be connected with the auxiliary drive device in maneuvering operation and with the main drive device or with both of these drive devices in working operation. Here, the auxiliary drive device provides less working power than the main drive device. It is thus ensured that the working device of the construction machine can be accelerated to its working speed or placed in a working mode rapidly after a maneuvering operation, while working operation is not possible by the drive of the auxiliary drive device. The security function thus remains reliably intact. It is noted here that such an embodiment with an auxiliary drive device and a main drive device can also be applied to conventional apparatuses for processing ground surfaces. It principally offers the possibility of switching an apparatus quickly between maneuvering and working operation.
In one embodiment, the drive device is adapted in such a way that, as a result of the auxiliary drive device, a synchronization of the working speed of the working device, especially its rotational speed, with the drive speed of the main drive device is possible, especially in maneuvering operation. A “switching” between the main drive device and the auxiliary drive device and especially a reactivation of the connection between the main drive device and the working device can thus be ensured rapidly, while the processing time for a given ground surface and in particular the time required for switching are reduced.
According to one embodiment, the drive device and especially the auxiliary drive device are adapted in such a way that the drive device can be accelerated by the auxiliary drive device in particular to the working speed of the main drive device during a decoupling of the main drive device from the working device as well as in maneuvering operation. This way, it is possible to accelerate the working device back to the speed of the main drive device, especially shortly before the conversion of the machine from maneuvering operation back to working operation, so that a switching and the renewed commencement of working operation are possible in a simple manner without interruptions.
The auxiliary drive device preferably comprises an electric or hydraulic drive so that rapid response characteristics are guaranteed. Preferably, the “charging” of the auxiliary drive device occurs by means of the main drive device and in particular in the working state in which the main drive device is alleviated, i.e., for example, in maneuvering operation.
In one embodiment, the coupling device preferably comprises a belt drive. Its belt tension is preferably adjustable by means of the control device, especially by way of a belt tightener, for controlling the frictional connection and/or the coupling slip. The belt drive preferably comprises a hydraulic or similarly modifiable belt tightener. The above safeguards during maneuvering operation can thus be easily ensured.
The invention will be described below with reference to examples which will be explained below in greater detail with reference to the drawings.
The same reference numerals will be used in the description below for the same and functionally equivalent parts.
The apparatus or construction machine 1 as shown in
The lowered position shown here corresponds to the working position or working operation in which the illustrated ground surface 13 is milled off. As shown, the rotational direction of the working device 4 runs opposite to the direction of movement of the apparatus 1 or the direction of rotation of the wheels 2 in working operation. In the lifted or maneuvering position (not shown), the working device 4 is no longer engaged with the ground surface 13 to be milled. In this position, the apparatus is moved “backwards” to the starting point of a new milling strip. During this changeover, the rotational movement of the working device 4 and the direction of movement of the apparatus 1 are synchronous. If an uncontrolled engagement of the working device 4 with the ground surface 13 or another impediment occurs, the apparatus 1 is accelerated in an abrupt and uncontrolled manner. It is this “malfunction” that shall be avoided.
This is possible in particular by means of a reduction of the drive power transferred to the working device 4 in maneuvering operation. For this purpose, working parameters and load parameters of the apparatus 1 are detected by way of corresponding sensors, the detected parameters are compared with existing set reference parameters and corresponding safeguards remedying the “malfunction” outlined above are initiated by way of a suitable control device. A sensor device with different sensors for detecting a deviation of at least one working parameter or load parameter from the set parameter value is provided. In this regard, the apparatus 1 can principally be provided with individual sensors or a combination of these sensors. The apparatus 1 according to
The load sensor 8 detects the load parameters acting on the moving device 2 such as weight loads, acceleration loads or changes in the latter in order to detect any unexpected changes in force or alleviation not initiated by the operator. If, for example, there is a sudden engagement of the working device 4 with the ground surface 13 in maneuvering operation because, e.g., the wheels 2 of the apparatus 1 pass through a depression, this engagement would lift the apparatus 1, leading to a brief alleviation of the lifting devices 5 and to a corresponding detection at the load sensors 8. A “malfunction” thus detected in maneuvering operation leads to a direct reaction in the drive system 6 of the working device 4, while the frictional connection between the drive device 6 and the working device 4 and/or the power provided or made available by the drive device 6 to the working device 4 is reduced.
This analogously applies to the inclination sensor which detects a change in the inclination of the apparatus caused by similar events. In this case as well, the frictional connection between the drive device 6 and the working device 4 and/or the power provided or made available by the drive device 6 to the working device 4 is reduced via a corresponding control signal.
The workload sensor 10, on the other hand, detects the power consumption, the working speed and/or the speed of the working device or the milling device 4 provided here or changes in the latter. Once an especially abrupt rise or fall is detected, a corresponding control signal is generated and the frictional connection between the drive device 6 and the milling device 4 and/or the power provided or made available by the drive device 6 to the working device 4 is reduced.
The working device 4 is coupled with the auxiliary drive device 18 via the coupling device 19 in maneuvering operation, whereas a connection is made with the main drive device 15 by means of the coupling device 16 in working operation. The auxiliary drive device 18 provides the working device 4 in the coupled state with less working power than the main drive device 15. It is thus ensured that the working device 4 of the apparatus is kept in maneuvering operation at an especially continuous rotational speed so that the operational state can be reached again rapidly at the beginning of a new working operation. In order to prevent an uncontrolled acceleration or damage to the apparatus 1 in maneuvering operation, the drive power provided by the auxiliary drive device 18 is set in such a way that the “idling operation” of the working device 4 is ensured but no working operation is possible. It is also possible in a similar embodiment to lower the rotational speed of the working device 4 in maneuvering operation or even to reduce the same to zero and to accelerate to working speed or a similar speed shortly before the renewed switching to working operation in which re-coupling with the main drive device 15 is possible. In this regard, a synchronization of the working speed of the working device 4 with the drive speed of the main drive device 15 is thus possible by means of the auxiliary drive device 18 especially in maneuvering operation.
The sensors 10 and 8 shown here are also load and workload sensors. They are used inter alia for monitoring the operation of the drive devices, in particular for detecting and synchronizing the rotational speeds of the auxiliary drive device 18, the main drive device 15 and the working device 4. It is further possible to make inferences via the sensors with respect to the state of the drive device 6 including the coupling devices 16, 19.
For the improved detection of a malfunction, the performance of the coupling device 16 for severing the connection 17 (shown schematically here) between the drive device 6 and the milling device or working device 4 can be varied. In the case of the hydraulically actuated coupling 16 shown here, this occurs by way of a limitation of the transferable torque or the transferable drive power by a change of the coupling pressure, shown in diagram 9. This pressure can be set individually for the construction machine by means of an adjusting device 11. The transferable power of the hydraulically actuated coupling device 16 is ideally set to a level so that in particular it does not slip and thus does not produce any increased wear and tear in the coupling device 16. The diagram shown here also shows an apparatus 1 in which the frictional connection or the coupling slip of the coupling device 16 is adjustable by means of a control device. This way, the drive device 4 can be further driven in maneuvering operation, while it is still ensured that, as a result of the reduced frictional connection, no acceleration of the apparatus 1 is initiated via its drive device 6 in case of unintended contact of the working device 4 with the ground surface 13.
While the present invention has been illustrated by description of various embodiments and while those embodiments have been described in considerable detail, it is not the intention of Applicants to restrict or in any way limit the scope of the appended claims to such details. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of Applicants' invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2010 014 893.8 | Apr 2010 | DE | national |
