Method for adjusting the rotational speed of an internal combustion engine of a road-building machine, and road-building machine for said method

Abstract

A method for adjusting the rotational speed of an internal combustion engine of a road-building machine which, in addition to a traction drive, has hydraulic motors which are connected to the internal combustion engine and which serve for driving working assemblies, in which method the rotational speed is adjusted as a function of the present power demand of the working assemblies, characterized in that the hydraulic motors are operated using fixed-displacement pumps, and residual volume flows presently to be discharged are reduced by flow valves for hydraulic motors of active working assemblies, for which purpose the rotational speed of the internal combustion engine is automatically adapted during working operation.

Claims

1. A method for adjusting the rotational speed of an internal combustion engine of a road-building machine, which, in addition to a traction drive, has hydraulic motors, connected to the internal combustion engine, for the driving of working assemblies, and in which method the rotational speed is adjusted dependent on the current power requirement of the working assemblies, wherein the hydraulic motors are operated using fixed displacement pumps and residual volume flows of flow control valves for hydraulic motors of active working assemblies, which residual volume flows are currently to be discharged, are reduced, for which purpose the rotational speed of the internal combustion engine is automatically adapted during working operation, the method comprising adjusting using a controller the flow control valves via a control line.

2. The method according to claim 1, further comprising adjusting with the controller such that the flow control valve of the hydraulic motor of the currently highest loaded working assembly, having then the smallest residual volume flow, gives the setting of the rotational speed signal for the adjustment of the rotational speed of the internal combustion engine.

3. The method according to claim 2, wherein the reduction of the residual volume flows of the flow control valves of a plurality of hydraulic motors is linked in the manner of a master-slave architecture, according to which the residual volume flow of the flow control valve of the hydraulic motor of the currently highest loaded working assembly determines the setting of the rotational speed signal as the master, which the flow control valves of the hydraulic motors of the other active working assemblies follow as slaves.

4. The method according to claim 1, further comprising minimizing at least the residual volume flow of the at any one time highest loaded working assembly.

5. The method according to claim 1, further comprising detecting the current power requirement of individual working assemblies and notifying the control apparatus.

6. The method according to claim 1, further comprising operating the traction drive independently from the rotational speed of the internal combustion engine.

7. A road-building machine having an internal combustion engine for driving a traction drive as well as a plurality of hydraulic motors for working assemblies, and having a controller for adjusting the rotational speed of the internal combustion engine dependent on the current power requirement of the working assemblies, wherein each of the plurality of hydraulic motors can be operated by means of a fixed displacement pump, which is drivable by the internal combustion engine and the full volume flow of each of which can be influenced by means of a respective flow control valve, and the controller is connected as a connecting link between the flow control valves of the hydraulic motors and a rotational speed sensor of the internal combustion engine and has an adaptation control circuit, which provides a rotational speed signal set to a reduction of the residual volume flows of the flow control valves for hydraulic motors of active working assemblies, which residual volume flows are currently to be discharged, wherein the controller adjusts the flow control valves via a control line.

8. The road-building machine according to claim 7, wherein the adaptation control circuit is designed for making a selection according to which the flow control valve of the hydraulic motor of the currently highest loaded working assembly, having then the smallest residual volume flow, gives the setting of the rotational speed signal for the adjustment of the rotational speed of the internal combustion engine.

9. The road-building machine according to claim 8, wherein the adaptation control circuit is designed for linking the reduction of the residual volume flows of the flow control valves of a plurality of hydraulic motors in the manner of a master-slave architecture, according to which the residual volume flow of the flow control valve of the hydraulic motor of the currently highest loaded working assembly determines the setting of the rotational speed signal as the master, which the flow control valves of the hydraulic motors of the other active working assemblies follow as slaves.

10. The road-building machine according to claim 7, wherein sensors, which indicate the current power requirement of individual working assemblies, are connected to the controller.

11. The road-building machine according to claim 7, wherein the controller is connected to a traction drive pump, which is driven by the internal combustion engine, in order to regulate a traction drive motor, which is fed by the traction drive pump, to a selectable running speed independently from the rotational speed of the internal combustion engine.

12. A road finisher configured according to claim 7, wherein the working assemblies are a tamper and vibrators of a paving screed, a spreading auger, and a conveyor of a road finisher.

Description

(1) The invention is explained in greater detail below with reference to the illustrative embodiment represented in the appended drawing.

(2) FIG. 1 shows a block diagram for the adjustment of the rotational speed of an internal combustion engine of a road-building machine.

(3) As shown in FIG. 1, the invention relates to a method for adjusting the rotational speed of an internal combustion engine 1 of a road-building machine, in particular of a road finisher, a road milling machine or the like, which, in addition to a traction drive 2, has hydraulic motors 3, connected to the internal combustion engine 1, for the driving of working assemblies. In a road finisher, the working assemblies include, for instance, a tamper bar, a vibration device for a screed, a conveyor belt for material to be laid, and a spreading auger, which, moreover, are able to be provided in multipart or multiple arrangement.

(4) The rotational speed of the internal combustion engine 1 can be adjusted dependent on the current power requirement of the working assemblies, for which purpose the internal combustion engine 1 has a rotational speed adjusting device 4.

(5) The hydraulic motors 3 are operated using fixed displacement pumps 5. The fixed displacement pumps 5 always generate the full volume flow for a specific rotational speed of the internal combustion engine. The amount of the constant volume flow is set by the rotational speed of the internal combustion engine 1.

(6) Since the fixed displacement pumps 5 always generate the full volume flow, a residual volume flow which is not required for the respective hydraulic motor 3 that is to be fed is discharged via a flow control valve 6. The residual volume flows of the flow control valves 6 for hydraulic motors 3 of active working assemblies, which residual volume flows are currently to be discharged dependent on a paving-working operation of the road-building machine, are now reduced according to the invention, for which purpose the rotational speed of the internal combustion engine is automatically adapted during paving-working operation. An increase or reduction of the rotational speed of the internal combustion engine 1 increases or reduces the volume flow of the fixed displacement pumps 5. By means of the adjustment of the rotational speed of the internal combustion engine 1, the volume flow of the fixed displacement pumps 5 is consequently altered such that the residual volume flows of the fixed displacement pumps 5 are influenced in an energy-optimized manner. In paving-working operation, the internal combustion engine 1 is consequently no longer operated at the nominal rotational speed, but at a rotational speed which is set on a load-dependent basis and is dependent on the power requirement of the active working assemblies. The power requirement or energy requirement is here, in particular, a volume or rotational speed requirement.

(7) To this end, a controller 7, which conducts an adaptation of the rotational speed of the internal combustion engine 1 via a rotational speed signal line 8, is provided.

(8) The adaptation is preferably realized such that the flow control valve 6 of the hydraulic motor 3 of the currently highest loaded working assembly, having then the smallest residual volume flow, gives the setting of the rotational speed signal for the adjustment of the rotational speed of the internal combustion engine 1. The optimization of energy usage by adjustment of the rotational speed of the internal combustion engine 1 can be done to the point where at least one, preferably the smallest of the residual volume flows, is brought to approximately zero. The remaining residual volume flows inevitably follow this degree of adjustment and are likewise reduced. Since the energy requirement of the hydraulic motors 3 for the various working assemblies in paving-working operation is different, the degree of the reduction of the residual flows is likewise different. The controller 7 adjusts the flow control valves 6 via a control line 9.

(9) The reduction of the residual volume flows of the flow control valves 6 of a plurality of hydraulic motors 3 can be linked in the manner of a master-slave architecture, according to which the residual volume flow of the flow control valve 6 of the hydraulic motor 3 of the currently highest loaded working assembly determines the setting of the rotational speed signal as the master, which the flow control valves 6 of the hydraulic motors 3 of the other active working assemblies follow as slaves.

(10) Preferably, at least the residual volume flow of the at any one time highest loaded working assembly is minimized or adjusted approximately to zero. The highest consumer then receives the full volume flow of the associated fixed displacement pump 5 as a result of the appropriately adjusted rotational speed of the internal combustion engine 1, while the flow control valves 6 can still discharge residual volume flows, which then, however, are at least reduced. The road-building machine is thereby operated more economically.

(11) The current power requirement of individual working assemblies is detected and notified to the control device 7. By means of sensors 10, which are connected via data lines 11 to the controller 7, the energy requirement of the individual active working assemblies during paving-working operation can be continuously determined and delivered as input data to the controller 7 for an automatic load-dependent adaptation of the rotational speed of the internal combustion engine 1.

(12) For the traction drive 2, an additional hydraulic pump 12 is provided in order to be able to adjust the traction drive independently from the rotational speed of the internal combustion engine 1. Via control lines 13, 14, the controller 7 can adjust the traction drive independently from the energy-optimized adjustment of the rotational speed of the internal combustion engine 1, since also an energy-optimized reduction of the rotational speed of the internal combustion engine 1 relative to its nominal rotational speed in a paving-working operation provides sufficient power for the traction drive 2 to enable adjustment to a selectable running speed.

(13) For the implementation of the above-described method, a road-building machine, in particular a road finisher, having an internal combustion engine 1 for driving a traction drive 2 as well as a plurality of hydraulic motors 3 for working assemblies (not shown), is provided. In addition, a control apparatus for a controller 7 for adjusting the rotational speed of the internal combustion engine 1 dependent on the current power requirement of the working assemblies is provided.

(14) Each of the plurality of hydraulic motors 3 can be operated by means of a fixed displacement pump 5, which is drivable by the internal combustion engine 1 and the full volume flow of each of which can be influenced by means of a respective flow control valve 6, and the controller 7 of the control device is connected as a connecting link between the flow control valves 6 of the hydraulic motors 3 and a rotational speed sensor of the internal combustion engine 1 and has an adaptation control circuit, which provides a rotational speed signal set to a reduction of the residual volume flows of the flow control valves 6 for hydraulic motors 3 of active working assemblies, which residual volume flows are currently to be discharged.

(15) The adaptation control circuit for making a selection can be designed such that the flow control valve 6 of the hydraulic motor 3 of the currently highest loaded working assembly, having then the smallest residual volume flow, gives the setting of the rotational speed signal for the adjustment of the rotational speed of the internal combustion engine 1.

(16) The adaptation control circuit can be designed for linking the reduction of the residual volume flows of the flow control valves 6 of a plurality of hydraulic motors 3 in the manner of a master-slave architecture.