APPARATUS AND METHOD FOR OPERATING A VEHICLE COOLING SYSTEM

Abstract

A vehicle cooling system includes a first fan assembly, a second fan assembly, and a control unit. The first fan assembly generates a main cooling flow acting upon a first cooler arrangement. The second fan assembly generates a secondary cooling flow adjacent to the main cooling flow and acting upon a second cooler arrangement. The secondary cooling flow is branched off from the main cooling flow via the second fan assembly. The main and secondary cooling flows pass through a filter element located upstream of the first and second fan assemblies and the first and second cooler arrangements. The control unit is configured to determine an actual value of a rotational speed variable of the second fan assembly, compare the actual value with a desired value specified for a cleaned state of the filter element, and generate a trigger signal to initiate a reversing operation of the first fan assembly.

Claims

1. A vehicle cooling system comprising: a first fan assembly generating a main cooling flow acting upon a first cooler arrangement; a second fan assembly generating a secondary cooling flow adjacent to the main cooling flow and acting upon a second cooler arrangement, the secondary cooling flow being branched off from the main cooling flow via the second fan assembly, the main and secondary cooling flows passing through a filter element located upstream of the first and second fan assemblies and the first and second cooler arrangements; and a control unit configured to determine an actual value of a rotational speed variable of the second fan assembly, compare the actual value with a desired value specified for a cleaned state of the filter element, and generate a trigger signal to initiate a reversing operation of the first fan assembly in order to blow out the filter element by means of the first fan assembly by reversing the direction of the main cooling flow when the comparison result lies outside a predetermined rotational speed tolerance range.

2. The system of claim 1, wherein the actual value of the rotational speed variable is determined via the control unit communicating with a sensor detecting a rotational speed of the second fan assembly.

3. The system of claim 1, wherein the actual value of the rotational speed variable is determined via the control unit based on a control variable for operating the second fan assembly.

4. The system of claim 1, wherein the desired value of the rotational speed variable that is specified for a cleaned state of the filter element is fixedly predetermined.

5. The system of claim 1, wherein the desired value of the rotational speed variable that is specified for a cleaned state of the filter element is variably predetermined by the control unit depending on a determined actual cooling requirement.

6. The system of claim 1, wherein a user interface for outputting operator information informing of the necessity of carrying out a reversing operation is activated by means of the trigger signal.

7. The system of claim 1, wherein an actuating device intended for automatically carrying out the reversing operation is activated by means of the trigger signal.

8. The system of claim 7, wherein the reversing operation is automatically carried out by the control unit after previous enabling by the operator.

9. A method for operating a vehicle cooling system comprising: generating via a first fan assembly a main cooling flow acting upon a first cooler arrangement; generating via a second fan assembly a secondary cooling flow adjacent to the main cooling flow and acting upon a second cooler arrangement, the secondary cooling flow being branched off from the main cooling flow via the second fan assembly; passing the main and secondary cooling flows through a filter element located upstream of the first and second fan assemblies and the first and second cooler arrangements; determining via a control unit an actual value of a rotational speed variable of the second fan assembly; comparing via the control unit the actual value with a desired value specified for a cleaned state of the filter element; and generating via the control unit a trigger signal to initiate a reversing operation of the first fan assembly in order to blow out the filter element by means of the first fan assembly by reversing the direction of the main cooling flow when the comparison result lies outside a predetermined rotational speed tolerance range.

10. The method of claim 9, wherein the actual value of the rotational speed variable is determined via the control unit communicating with a sensor detecting a rotational speed of the second fan assembly.

11. The method of claim 9, wherein the actual value of the rotational speed variable is determined via the control unit based on a control variable for operating the second fan assembly.

12. The method of claim 9, wherein the desired value of the rotational speed variable that is specified for a cleaned state of the filter element is fixedly predetermined.

13. The method of claim 9, wherein the desired value of the rotational speed variable that is specified for a cleaned state of the filter element is variably predetermined by the control unit depending on a determined actual cooling requirement.

14. The method of claim 9, wherein a user interface for outputting operator information informing of the necessity of carrying out a reversing operation is activated by means of the trigger signal.

15. The method of claim 9, wherein an actuating device intended for automatically carrying out the reversing operation is activated by means of the trigger signal.

16. The method of claim 15, wherein the reversing operation is automatically carried out by the control unit after previous enabling by the operator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The method according to the disclosure for operating a vehicle cooling system will be described in more detail below on the basis of the appended drawings. Here, identical reference designations relate to corresponding components or components which are of comparable function. In the drawings:

[0025] FIG. 1 shows a schematically illustrated vehicle cooling system of a utility vehicle in the form of an agricultural tractor;

[0026] FIG. 2 shows the vehicle cooling system shown in FIG. 1 during the carrying out of a reversing operation; and

[0027] FIG. 3 shows an exemplary embodiment, illustrated as a flow diagram, of the method according to the disclosure for operating the vehicle cooling system shown in FIG. 1.

DETAILED DESCRIPTION

[0028] The embodiments or implementations disclosed in the above drawings and the following detailed description are not intended to be exhaustive or to limit the present disclosure to these embodiments or implementations.

[0029] FIG. 1 shows a schematically illustrated vehicle cooling system 10 which is part of a utility vehicle in the form of an agricultural tractor 12.

[0030] The illustration of an agricultural tractor 12 is merely of an exemplary nature; it may, on the contrary, also be any other utility vehicle from the agricultural or forestry sphere, and also a construction vehicle.

[0031] The vehicle cooling system 10 which is accommodated in an engine compartment 14 of the agricultural tractor 12 has a first cooler arrangement 16 and a second cooler arrangement 18 accommodated spatially separately therefrom. The first cooler arrangement 16 comprises, inter alia, in addition to a high-temperature heat exchanger 20 for cooling a diesel engine 22, an oil cooler 24 and an air-conditioning system condenser 26, wherein the relevant cooler components lie in series and/or in parallel in a common main cooling flow 28 which is generated by means of a first fan assembly 32 designed as an axial fan 30. The axial fan 30 is set into rotation here via a belt drive 34 connected to the diesel engine 22.

[0032] Furthermore, the second cooler arrangement 18 is a charge air cooler 36 which is mounted adjacent inside the engine compartment 14 running upstream and substantially horizontally above the main cooling flow 28. The charge air cooler 36 serves for cooling the combustion air which is heated by means of a turbocharger 38 during the compression and is to be supplied to an intake tract 40 of the diesel engine 22 (the hose connections present in this respect are merely indicated for the sake of clarity in FIG. 1). In order to permit operation of the charge air cooler 36 which is independent of the first cooler arrangement 16, a second fan assembly 42 in the form of a further axial fan 44 which is driven by means of a hydraulic motor 46 is connected upstream. Instead of such a hydraulic drive, however, an electric drive in the form of an electric motor may also be provided. In this way, a secondary cooling flow 48 passing through the charge air cooler 36 is branched off from the main cooling flow 28. The heated secondary cooling flow 48 subsequently leaves the engine compartment 14 via an air outlet opening 52 which is formed on an upper side of an engine hood 50 (indicated by dashed lines).

[0033] To protect the cooler arrangements 16, 18 of the vehicle cooling system 10 against dust deposits and an associated degradation of the cooling power, the ambient air 54 required for generating main and secondary cooling flows 28, 48 is taken in via a filter element 56 lying upstream of the fan assemblies 32, 42 and the cooler arrangements 16, 18. The filter element 56 is in the form of a fine-mesh metal screen 58 which is designed as a particle filter and is located directly behind a front-side radiator grille 60 in the engine hood 50 of the agricultural tractor 12. In a departure therefrom, the filter element 56 can also be structurally integrated directly in the front-side radiator grille 60.

[0034] Since the surface of the metal screen 58 becomes clogged over time as dust-containing ambient air 54 passes through it, the filter element 56 has to be cleaned at regular intervals. For this purpose, the vehicle cooling system 10 provides the option of setting the axial fan 30 of the first cooling arrangement 16 into a reversing operation in which the direction of the main cooling flow 28 is reversed such that the filter element 56 can be blown off toward the external environment and thereby cleaned.

[0035] For example, the axial fan 30 included by the first fan assembly 32 and intended for carrying out the reversing operation has a plurality of fan vanes 64 which project radially at a fan hub 62 and can be pivoted with respect to their angle of attack a by means of an actuating device 66. In this way, a reversal of the flow direction is possible without changing the direction of rotation of the axial fan 30. This operating state is reproduced in FIG. 2.

[0036] For the sake of completeness, it should be noted that the spatial arrangement of the fan assemblies 32, 42 and cooler arrangements 16, 18 illustrated in FIG. 1 reproduces one of a plurality of options. In the present case, the second cooler arrangement 18 is located with respect to the course of the main cooling flow 28 between the filter element 56 and the first cooler arrangement 16, but may also be located between the first cooler arrangement 16 and the first fan assembly 32.

[0037] The function of the further components illustrated in FIG. 1 will be explained below in conjunction with the method sequence reproduced in FIG. 3.

[0038] FIG. 3 shows here an exemplary embodiment, illustrated as a flow diagram, of the method according to the disclosure for operating the vehicle system 10. According thereto, the method is started in an initialization step 100, whereupon, in a first step 102, an actual value n.sub.act of a rotational speed variable which reproduces a rotational speed occurring at the second fan assembly 42, depending on the cooling requirement, is determined by a control unit 68 (e.g., a controller including a processor and memory). The cooling requirement dependency of the rotational speed of the second fan assembly 42 arises in the present case from the fact that a reduced cooling power, which is identified on the basis of a rise in temperature, is compensated for by a successive increase in the rotational speed.

[0039] The actual value n.sub.act of the rotational speed variable is determined in the first step 102 by the control unit 68 by a sensor by detecting the rotational speed of a fan wheel 70 included by the second fan assembly 42. For this purpose, use is made of an inductive rotational speed sensor 72 of conventional design which contactlessly detects the revolutions of a drive shaft 74 running between hydraulic motor 46 and fan wheel 70 and transmits a rotational speed signal corresponding thereto to the control unit 68.

[0040] Alternatively, the actual value n.sub.act of the rotational speed variable is determined by the control unit 68 in the first step 102 by computer in accordance with control variables provided for operation of the second fan assembly 42. The control variables present at a CAN data bus 76 of the agricultural tractor 12 are detected by a sensor and, when the control behavior of the hydraulic motor 46 is known, permit an unambiguous statement about the rotational speed occurring at the fan wheel 70. The control variables here represent a volumetric flow and/or pressure of a hydraulic supply provided for operating the hydraulic motor 46. Said control variables here are indirectly derived by the control unit 68 from an electric signal serving to actuate a valve (not shown) provided for predetermining a volumetric flow and/or pressure. By contrast, if an electric motor is used, the control variables arise from voltage and/or current of a power supply provided for operating same.

[0041] In a second step 104, the actual value n.sub.act of the rotational speed variable that is determined in the first step 102 is compared by the control unit 68 with a desired value n.sub.des specified for a cleaned state of the filter element 56.

[0042] If the control unit 68, in a third step 106, recognizes that the comparison result lies outside a predetermined rotational speed tolerance range Δn, it generates, in a fourth step 108, a trigger signal for initiating a reversing operation of the first fan assembly 32 in order to blow off the filter element 56 by means of the first fan assembly 32 by reversing the direction of the main cooling flow 28. Otherwise, the method returns again to the third step 106.

[0043] In other words, an excessive increase in the cooling requirement of the second cooler arrangement 18, which increase is derived from a rotational speed discrepancy observed in the fourth step 108, is used as an indicator of the necessity for carrying out an operation to clean the filter element 56.

[0044] According to a first option, the desired value n.sub.des of the rotational speed variable that is specified for a cleaned state of the filter element 56 is fixedly predetermined. The desired value n.sub.des is specified in such a manner that a maximum anticipated cooling requirement of the charge air to be cooled by means of the second cooler arrangement 18 is reliably covered. The desired value n.sub.des predetermined for the rotational speed variable is stored in a memory unit 78 communicating with the control unit 68.

[0045] In a departure therefrom, a second option makes provision that the desired value n.sub.des of the rotational speed variable that is specified for a cleaned state of the filter element 56 is not fixedly oriented to the maximum cooling requirement of the charge air to be cooled by means of the second cooler arrangement 18, but rather is variably predetermined by the control unit 68 depending on a determined actual cooling requirement. The actual cooling requirement of the charge air is derived by the control unit 68 inter alia from details available via the CAN data bus 76 in respect of an engine rotational speed or engine power of the diesel engine 22, the external temperature, the air humidity, the charge air pressure and/or the position of adjustable turbocharger vanes.

[0046] To initiate the cleaning operation, it is provided, in a fifth step 110, that a user interface 80 for outputting operator information informing of the necessity of carrying out a reversing operation is activated by means of the trigger signal. The user interface 80 has a touch-sensitive display 82 which is accommodated in a driver's cab of the agricultural tractor 12 or else is part of a mobile terminal 84 which is connected in terms of data exchange to the control unit 68 via a wireless interface 86. The operator information is output visually via the touch-sensitive display 82, but also audibly by means of an acoustic signal generator 88 included by the user interface 80.

[0047] In this connection, in a seventh step 114, after enabling by an operator in an upstream sixth step 112, the actuating device 66 included by the first fan assembly 32 and intended for automatically carrying out the reversing operation is activated by means of the trigger signal. For this purpose, the actuating device 66 comprises an electrically, hydraulically, or pneumatically actuable arrangement 90, integrated in the fan hub 62 of the fan wheel 70, for changing the angle of attack a of the fan vanes 64. The arrangement 90 is actuated electrically, hydraulically, or pneumatically here by means of a controller unit 92 which is connected to the control unit 68. If the enabling by an operator is not carried out in the sixth step 112, the method is ended directly in a concluding step 116.

[0048] The touch-sensitive display 82 included by the user interface 80 is used for the enabling by the operator in the sixth step 112. In this case, the driver of the agricultural tractor 12 obtains the opportunity of searching for a suitable parking space so that an undesirable blowing off of the filter element 56 in closed buildings, such as barns or workshops, can be prevented.

[0049] Subsequently, the method according to the disclosure is ended in the concluding step 116.

[0050] The terminology used herein is for the purpose of describing example embodiments or implementations and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the any use of the terms “has,” “includes,” “comprises,” or the like, in this specification, identifies the presence of stated features, integers, steps, operations, elements, and/or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

[0051] Those having ordinary skill in the art will recognize that terms such as “above,” “below,” “upward,” “downward,” “top,” “bottom,” etc., are used descriptively for the figures, and do not represent limitations on the scope of the present disclosure, as defined by the appended claims. Furthermore, the teachings may be described herein in terms of functional and/or logical block components or various processing steps, which may include any number of hardware, software, and/or firmware components configured to perform the specified functions.

[0052] Terms of degree, such as “generally,” “substantially,” or “approximately” are understood by those having ordinary skill in the art to refer to reasonable ranges outside of a given value or orientation, for example, general tolerances or positional relationships associated with manufacturing, assembly, and use of the described embodiments or implementations.

[0053] As used herein, “e.g.,” is utilized to non-exhaustively list examples and carries the same meaning as alternative illustrative phrases such as “including,” “including, but not limited to,” and “including without limitation.” Unless otherwise limited or modified, lists with elements that are separated by conjunctive terms (e.g., “and”) and that are also preceded by the phrase “one or more of” or “at least one of” indicate configurations or arrangements that potentially include individual elements of the list, or any combination thereof. For example, “at least one of A, B, and C” or “one or more of A, B, and C” indicates the possibilities of only A, only B, only C, or any combination of two or more of A, B, and C (e.g., A and B; B and C; A and C; or A, B, and C).

[0054] While the above describes example embodiments or implementations of the present disclosure, these descriptions should not be viewed in a restrictive or limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the appended claims.