Method and device for regulation of a cooling fan drive on an internal combustion engine in a construction or working machine

Abstract

The invention relates to a method for regulation of a cooling fan drive on an internal combustion engine, in particular equipped with several independent cooling circuits, in a construction or working machine, whereby the power drain of the cooling fan drive is set to approximately zero during certain working stages of the construction and/or working and said power drain may be added to the capacity for the working stage.

Description

[0001] The invention relates to a method for regulating a cooling fan drive on an internal combustion engine, in particular provided with a number or separate cooling circuits and used in construction or working machines.

[0002] German reference DE-A 195 35 674 proposes a method for regulating the cooling system of an excavator drive, in particular a high-performance diesel-engine drive. For this method, a thermostat provided near the diesel engine opens up the flow path from the diesel engine to a water cooled-radiator that operates jointly with the fan at a predetermined water temperature. A temperature gauge arranged in the area of the flow path controls the fan in such a way that within a predetermined temperature range above the thermostat-controlled water temperature, the speed of the fan is controlled in the range between 0 min−1 and a maximum speed.

[0003] German reference DE-A 198 25 759 discloses a hydraulic drive component with a variable displacement pump that is connected flow-wise in a closed circuit to an engine and is designed to drive an auxiliary device such as a fan. An auxiliary pump can be connected operationally to the pump, the engine and a container for replenishing the flow medium lost in the closed circuit. An auxiliary circuit that is connected to the pump has a circulation opening that is connected with respect to the flow to the closed circuit in downstream direction of the engine, so as to reduce the required container volume.

[0004] Construction or working machines, particularly hydraulic excavators, are designed for specific peak performances, for example computed on the basis of identical working movements that are in part repeated constantly, such as the lifting of the boom and the pivoting of the upper carriage relative to the undercarriage.

[0005] The internal combustion engines of these construction or working machines, in particular of hydraulic excavators, are normally cooled with water, wherein a fan controlled by a separate hydraulic drive is provided. The fan can be turned on/turned off and, in particular, can be actuated by the internal combustion engine in dependence on the increasing temperatures in the cooling circuit of the internal combustion engine.

[0006] During normal operations of the construction or working machine, particularly of the hydraulic excavator, the fan as a rule is activated once a predetermined temperature value is exceeded in the cooling circuit of the internal combustion engine. The activated fan requires a specific driving power for controlling the temperature in the cooling circuit.

[0007] As a result of the power drain caused by the fan activation, the full driving power of the internal combustion engine is not available, for example, for raising a boom and the internal combustion engine capacity assigned to the operating sequence may no longer be sufficient for certain limit ranges.

[0008] Thus, it is the object of the invention to provide a method and a device for regulating a fan drive in such a way that the capacity can be raised for the working movements of the construction or working machine, without this leading to a reduction in power for the internal combustion engine.

[0009] This object is solved with a method for regulating a fan drive on an internal combustion engine, in particular provided with several independent cooling circuits, in construction and/or working machines. For this, the power consumption of the fan drive is set to approximately zero for predetermined operating sequences of the construction and/or working machine and the fan power consumption is added to that of the operating sequence.

[0010] Advantageous modifications of the subject matter of the invention follow from the associated dependent method claims.

[0011] This object is furthermore solved with a device for regulating a fan drive on an internal combustion engine, in particular provided with several independents cooling circuits and used in construction and/or working machines. The device comprises at least one PI regulator for each cooling circuit, at least one downstream-connected comparator, as well as at least one pulse-width modulator that is operatively connected to a control unit.

[0012] The regulator according to a different idea behind the invention is a &mgr; controller-PI regulator.

[0013] The subject matter of the invention makes it possible to adjust at least two different set temperature values for several independently operating cooling circuits in an internal combustion engine with the aid of a fan drive and via a joint control unit. As a result, the power consumption of the fan drive is set to zero for specific working movements (fan runs along with no load) and the fan capacity can then be added to that of the working movement.

[0014] A set value/actual value comparison is performed with a &mgr; controller-PI regulator for each cooling circuit and the required adjustment value is determined for each cooling circuit. The downstream-connected comparator then determines the maximum adjustment value from the individual adjustment values and transmits this maximum value to a PWM stage (pulse width modulation stage) that is connected to the control unit. For a specific working movement, for example when raising the boom of a hydraulic excavator, the set temperature values of the cooling circuits are essentially raised simultaneously. As a result, the power consumption of the fan drive is set to approximately zero (fan runs along with no load) and the lifting capacity increases by the amount of the fan drive capacity.

[0015] Depending on the dimensions of the construction or working machine, in particular a large hydraulic excavator, the lifting capacity for raising the boom can thus be increased without overheating of the drive unit or units. This takes into account that the fan driving power is not assigned continuously, but is required only for predetermined, defined working movements of the construction or working machine.

[0016] The single FIGURE is described in the following and represents a schematic diagram.

[0017] Shown is an internal combustion engine 1, provided for this example with two independent cooling circuits 2, 3, which in turn are connected via a controller 9 with control unit 10 on a controllable fan drive 4 to a fan wheel 5. Also shown is an equipment part 6, for example the boom of a hydraulic excavator that is not shown in further detail herein. This equipment part is positioned on an upper carriage 7 that is only indicated herein and can be lowered or raised with the aid of hydraulic cylinders 8. Also indicated are the hydraulic circuit 11, which is responsible for the lifting and lowering of the equipment component 6, the hydraulic circuit 12 that is responsible for the fan drive 4, as well as the hydraulic circuit 20 that is necessary for supplying the control unit 10. A &mgr; controller-PI regulator 13, 14 is provided for each cooling circuit 2, 3, which performs a set value/actual value comparison and computes the associated adjustment values for each cooling circuit 2, 3. The set values are provided to the &mgr; controllers-PI regulators 13, 14 via a reversing switch 15. The values determined by the &mgr; controllers-PI regulators 13, 14 are transmitted to a downstream-connected comparator 16. This comparator determines the maximum adjustment value from the individual adjustment values and transmits this maximum adjustment value to a PWM (pulse width modulation) stage 17 that is connected via the line 18 to the control unit 10. Among other things, a portion of the driving capacity of the internal combustion engine 1 is thus assigned to the operating sequence of the equipment component 6 while another portion of the driving capacity is required for the fan wheel 5, so as to protect the internal combustion engine 1 against overheating. For specific operating sequences, for example when raising the equipment component 6 with the aid of hydraulic cylinders 8, the combustion engine 1 may not have enough driving power for raising the equipment component 6.

[0018] According to the invention, a switch 19 and the reversing switch 15 are used to raise the set temperature values for the cooling circuits 2, 3 for this type of working movement to higher set temperature values. As a result, the power consumption of the fan drive 4 is set to approximately zero via the line 18 and the control unit 10. The fan wheel 5 then stops running or runs along without load. The hydraulic driving power of the fan drive 4, which is no longer needed for operating the fan wheel 5, is thus added to the lifting capacity of the equipment component 6 without resulting in overheating of the internal combustion engine 1. As soon as the specific movement sequence is completed, the hydraulic fan drive 4 is again switched to the fan wheel 5, wherein the increased set temperature values for each cooling circuit 2, 3 are again assigned via the switch 19 and the reversing switch 15 to a lower set temperature value. This power interplay can be repeated in an optional sequence, but must be seen in the final analysis as depending on the maximum capacity to be assigned to the respective movement sequence.

Claims

1. (Original) A method for regulating a fan drive (4) on an internal combustion engine (1), in particular provided with several independent cooling circuits (2, 3) and used in construction and/or working machines in that the power consumption of the fan drive (4) is set approximately to zero for predetermined operating sequences of the construction and/or working machine and that the fan power consumption is added to that of the operating sequence.

2. (Original) The method according to claim 1, characterized in that at least two different set temperature values are adjusted for the cooling circuit (2, 3), wherein for predetermined operating sequences of the construction or working machine the one set temperature value is adjusted to a higher set temperature value with the aid of a switch (19) and a reversing switch (15) and that the operating capacity of the fan drive (4) is set to approximately zero.

3. (Currently Amended) The method according to claim 1 or 2, characterized in that if several cooling circuits (2, 3) exist, at least two different set temperature values are adjusted for each cooling circuit (2, 3) via a joint control unit (10).

4. (Currently Amended) The method according to one of the claims claim 1 to 3, characterized in that a set value/actual value temperature comparison is carried out with a &mgr; controller-PI regulator (13, 14) for each cooling circuit (2, 3) and that the permissible adjustment value for each cooling circuit (2, 3) is determined.

5. (Currently Amended) The method according to one of the claims claim 1 to 4, characterized in that a comparator (16) that operates jointly with the PI regulator(s) (13, 14) determines a maximum adjustment value from the individual adjustment value(s) and transmits this maximum adjustment value to a pulse width modulation stage (17) that is operatively connected to the control unit (10).

6. (Currently Amended) The method according to one of the claims claim 1 to 5, characterized in that for a predetermined working movement of the construction and/or working machine, in particular for lifting the boom (6) of a hydraulic excavator, the set temperature values of all cooling circuits (2, 3) are raised essentially at the same time, thus causing the power consumption of the fan drive (4), particularly during the no-load operation of the fan wheel (5), to be set approximately to zero and the driving power of the fan drive (4) to be assigned to the movement sequence of the construction and/or working machine, in particular for increasing the lifting capacity of the boom (6).

7. (Original) A device for regulating a fan drive (4) on an internal combustion engine (1), in particular provided with several independent cooling circuits (2, 3) and used in construction and/or working machines, said device comprising at least one reversing switch (15), at least one PI regulator (13, 14) for each cooling circuit (2, 3), at least one downstream-connected comparator (16), as well as at least one pulse width modulator (17) that is operatively connected to a control unit (10).

8. (Original) The device according to claim 7, characterized in that the regulator (13, 14) is a &mgr; controller-PI regulator.