Patent Publication Number: US-2023139344-A1

Title: Clutch device for a vehicle fan

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to German Patent Application No. 102021128076.1, filed on Oct. 28, 2021, which is hereby incorporated by reference. 
     FIELD OF THE DISCLOSURE 
     The disclosure relates to a clutch device for a vehicle fan. 
     BACKGROUND 
     A clutch device for a vehicle fan is, for example, in the form of what is known as a Visco clutch, in the case of which a valve is opened by means of a bimetallic element as a temperature of a vehicle assembly to be cooled increases, in order to convey pressurized hydraulic liquid into a working space of the Visco clutch in order to increase the clutch closure. Consequently, the rotational speed of a fan impeller, driven by the Visco clutch, and therefore its cooling performance increase. 
     SUMMARY 
     In the case of some applications, the use of a Visco clutch is however too expensive and therefore uncommon. This applies, for example, to the case of the cooling of internal combustion engines in agricultural tractors of comparatively low power output classes. Here, a rigid coupling is usually brought about between a pulley wheel of a belt drive, driven by the internal combustion engine, and a fan impeller which serves to generate a cooling air stream which loads an engine heat exchanger. When the internal combustion engine is switched off, the belt drive comes to a standstill comparatively rapidly. On account of its mass moment of inertia, however, the fan impeller tends to rotate further for a certain time period. This leads to spinning of the pulley wheel which is connected to it along the stationary drive belt and therefore to undesired wear and perceptible vibrations and/or noise. 
     It is therefore an object to configure a clutch device of the type mentioned at the outset in such a way that, in the case of a rigid drive connection, it leads to an improved wear and noise behavior of the vehicle fan. 
     This object can be achieved by a clutch device with the features of one or more of the following embodiments. 
     A clutch device for a vehicle fan includes, a drive-side clutch element, an output-side clutch element, and a locking mechanism configured or arranged between the two clutch elements so that a rotary connection established between the clutch elements is released if a drive-side rotational speed drops or reduces in comparison with an output-side rotational speed. 
     The freewheel which is formed in this way can transmit a torque only in one rotational direction. In the case of opposite rotational directions of the two clutch elements with respect to one another, or if the output-side rotational speed is greater than the drive-side rotational speed, the rotary connection is released automatically. In this way, it can be ensured that a fan blade which is driven by means of the clutch device can rotate further in a reaction-free manner even in the case of a retardation or standstill of the drive-side clutch element. 
     Here, a use of the clutch device is not restricted to a certain vehicle fan. It can thus serve to generate a cooling air stream which loads an engine heat exchanger, but can also relate to any desired other applications in the automotive sector. Here, inter alia, a use in conjunction with an interior compartment ventilation or climate control system of a driver&#39;s cab of an agricultural vehicle is conceivable. 
     Additional features of the clutch device are apparent from the following embodiments. 
     The drive-side clutch element can have a hub which can be connected to a drive shaft, a plurality of radially pivotable locking claws being attached along an outer circumference of the hub, which locking claws are prestressed into a deflected locking position in each case by means of a spring element in order to establish the rotary connection. The hub has, for example, an internal thread, into which the drive shaft, connected to a pulley wheel, of a belt drive which can be driven by an internal combustion engine can be screwed. 
     There is the possibility in this case that a plurality of clutch ramps for engaging with a respective one of the locking claws are configured along an inner circumference of the output-side clutch element. In the case of an established rotary connection, the locking claws can bear with a front-side end against a ramp end which runs substantially transversely with respect to the rotational direction. Conversely, the locking claws can be pushed away radially inward out of the deflected locking position along an inner contour of the clutch ramps counter to the prestress which is generated by means of the respective spring element. The locking claws can have a curved course in such a way that they bear in each case in a shoulder region against the inner contour of the clutch ramps. On account of the increase produced in this way of the bearing area, friction-induced wear of locking claws and clutch ramps can be decreased significantly in freewheeling operation. Here, the two parts can be made of surface-tempered steel. 
     In addition, it is possible that the number of clutch ramps corresponds to that of the locking claws or is a multiple thereof. A total of from four to five locking claws and clutch ramps can be distributed uniformly along the outer circumference of the hub and the inner circumference of the output-side clutch element. The precise number of locking claws is ultimately dependent here on the torques which are to be transmitted by means of the clutch device. 
     A fastening flange for mounting a fan impeller can be configured on the output-side clutch element. The fan impeller which can be made of fiber-reinforced plastic comprises a plurality of fan blades which serve to generate an axial or radial cooling air stream. Here, the fan impeller can be screwed by means of a fastening hub to a ring with holes which is provided on the fastening flange. 
     The drive-side clutch element is received rotatably within the output-side clutch element, for example, by means of a deep groove ball bearing. The deep groove ball bearing usually comprises an inner and an outer ball race. The outer ball race can be inserted into a receiving opening, configured on the output-side clutch element, and can be fixed therein in a substantially play-free manner by means of a securing ring which engages into an inner groove which runs around on the receiving opening. In contrast, the inner ball race can be plugged onto a fastening projection, configured on the hub, and can bear there against a peripheral collar. A further securing ring which engages into a peripheral outer groove on the fastening projection can be situated on that side of the deep groove ball bearing which lies opposite the collar, which further securing ring fixes the deep groove ball bearing substantially without play on the fastening projection. 
     The above and other features will become apparent from the following detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The clutch for a vehicle fan will be described in greater detail in the following text on the basis of the appended drawings. Here, identical reference signs refer to components which coincide or are comparable with regard to their function. In the drawings: 
         FIG.  1    shows an exploded illustration of the constituent parts of one exemplary embodiment of the clutch device for a vehicle fan; 
         FIG.  2    shows a view of the clutch device according to  FIG.  1    in the assembled state in the case of an established rotary connection; 
         FIG.  3    shows a view of the clutch device illustrated in  FIG.  2   , in the case of a released rotary connection; and 
         FIG.  4    shows a sectional illustration of the clutch device in a state, in which it is installed on a vehicle fan. 
     
    
    
     DETAILED DESCRIPTION 
     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. 
       FIG.  1    shows an exploded illustration of the constituent parts of one exemplary embodiment of the clutch device for a vehicle fan which is shown in greater detail in  FIG.  4   . 
     Along a common rotational axis  12 , the clutch device  10  comprises a drive-side clutch element  14  and an output-side clutch element  16 . 
     The drive-side clutch element  14  has a hub  18  (in this regard, see also  FIG.  4   ). A plurality of radially pivotable locking claws  22  are attached along an outer circumference  20  of the hub  18 , which locking claws  22  are prestressed in each case by means of a spring element  24  into a deflected locking position which is illustrated in  FIG.  2   , with the result that a rotary connection can be established between the two clutch elements  14 ,  16 . 
     To this end, a plurality of clutch ramps  28  are configured along an inner circumference  26  of the output-side clutch element  16  for engaging with a respective one of the locking claws  22 . As can be seen in  FIG.  2   , in the case of an established rotary connection, the locking claws  22  bear with a front-side end  30  against a ramp end  32  which runs substantially transversely with respect to the rotational direction. 
     Conversely, in order to release the rotary connection, the locking claws  22  can be pushed away radially inwards out of the deflected locking position along an inner contour  34  of the clutch ramps  28  counter to the prestress which is generated by means of the respective spring element  24 , the said locking claws  22  being received at least partially by a respective recess  36  along the outer circumference of the hub  18 . This is the case, for example, in the case of opposite rotational directions of the two clutch elements  14 ,  16  with respect to one another or else when the output-side rotational speed is greater than the drive-side rotational speed. Freewheeling operation of this type is shown in  FIG.  3   . As a result, the clutch device  10 , more precisely the locking mechanism which is formed by way of the locking claws  22  and the clutch ramps  28 , transmits a torque only in the predefined rotational direction. 
     In the present case, the number of clutch ramps  28  corresponds to that of the locking claws  22 . As an alternative, however, they can also be a multiple thereof. According to the example, a total of four locking claws  22  and clutch ramps  28  are arranged distributed uniformly along the outer circumference  20  of the hub  18  and the inner circumference  26  of the output-side clutch element  16 . 
     In addition, the locking claws  22  have a tangentially curved course with regard to the outer circumference  20  of the hub  18 , in such a way that they bear in each case in a shoulder region  38  against the inner contour  34  of the clutch ramps  28 . On account of the increase provided in this way in the bearing area, friction-induced wear of locking claws  22  and clutch ramps  28  can be decreased significantly during freewheeling operation. Here, the two parts can be made of surface-tempered steel. 
     Furthermore,  FIG.  4    shows a sectional illustration of the clutch device  10  in a state, in which it is installed on a vehicle fan  40 . As can be seen by way of comparison with  FIG.  1   , the drive-side clutch element  14  is received rotatably within the output-side clutch element  16  by means of a deep groove ball bearing  42 . 
     The deep groove ball bearing  42  comprises an inner ball race  44  and an outer ball race  46 . The outer ball race  46  is inserted into a receiving opening  48  which is configured on the output-side clutch element  16 , and is fixed therein substantially without play by means of a securing ring  50  which engages into an inner groove  52  which runs around on the receiving opening  48 . In contrast, the inner ball race  44  is plugged onto the fastening projection  54 , configured on the hub  18 , and bears there against a peripheral collar  56 . A further securing ring  60  which engages into a peripheral outer groove  58  on the fastening projection  54  is situated on that side of the deep groove ball bearing  42  which lies opposite the collar  56 , which further securing ring  60  fixes the deep groove ball bearing  42  substantially without play on the fastening projection  54 . 
     The fastening flange  62  for mounting a fan impeller  64  which is shown in  FIG.  4    is configured on the output-side clutch element  16 . The fan impeller  64  which can be made of a fiber-reinforced plastic comprises a plurality of fan blades  66  which serve to generate an axial cooling air stream  68 . The fan impeller  64  is screwed by means of a fastening hub  70  to a ring  72  with holes which is provided on the fastening flange  62 . 
     The hub  18  which is enclosed by the drive-side clutch element  14  comprises an internal thread  74 , into which a drive shaft  78  which is connected to a pulley wheel  76  is screwed, with the result that the hub  18  and the drive shaft  78  are rotationally connected to one another. The pulley wheel  76  is a constituent part of a belt drive  82  which can be driven by an internal combustion engine  80  and is situated in the engine compartment  84  of an agricultural vehicle (not shown), for example an agricultural tractor. 
     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. 
     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. 
     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. 
     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). 
     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.