Patent Publication Number: US-2019178156-A1

Title: Engine device for vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims under 35 U.S.C. § 119(a) the benefit of Korean Patent Application No. 10-2017-0168658, filed on Dec. 8, 2017 in the Korean Intellectual Property Office, the entire contents of which are incorporated by reference herein. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an engine device for a vehicle, which is capable of improving fuel efficiency by reducing an engine load attributable to continuous operation of an auxiliary drive system. 
     2. Description of the Related Art 
     In general, a vehicle includes an auxiliary drive system, which is rotated by torque from an engine. Such an auxiliary drive system includes a generator, a compressor for an air conditioner, a water pump, etc. 
     The torque generated by the operation of the engine is transferred to a crankshaft, and is subsequently transferred to various auxiliary devices, which constitute the auxiliary drive system, via belts connected to the crankshaft. To this end, the crankshaft and the auxiliary drive system are provided with pulleys to receive torque via the belts. 
     In recently developed vehicles, one integrated belt is connected to an auxiliary drive system. However, because a single belt is connected to the pulleys of the auxiliary drive system, all of the pulleys of the auxiliary drive system are rotated when the engine operates, and thus torque loss occurs. 
     Accordingly, the engine output is reduced, and fuel efficiency and operational efficiency are deteriorated. 
     The information disclosed in this Background section is only for enhancement of understanding of the general background of the disclosure and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. 
     SUMMARY 
     Therefore, the present disclosure provides an engine device for a vehicle, which is capable of improving fuel efficiency by reducing an engine load attributable to continuous operation of an auxiliary drive system. 
     In accordance with the present disclosure, the above and other objects can be accomplished by the provision of an engine device for a vehicle, including a pulley unit connected with a crankshaft configured to be rotated by engine torque, the pulley unit being provided with a clutch pulley configured to be selectively rotated by the engine torque depending on whether electric power is applied, and an auxiliary drive system connected with the clutch pulley via a belt and configured to be rotated by torque from the clutch pulley. The pulley unit is configured such that the clutch pulley is not rotated when the auxiliary drive system is not rotated so as to minimize torque loss attributable to dispersion of engine torque. 
     The auxiliary drive system may include an air-conditioner compressor and an alternator, with a water pump provided separately. 
     The water pump may be an electric water pump that is selectively operated depending on application of electric power. 
     The engine device may further include a battery electrically connected to the alternator, and the battery may be a lithium ion battery. 
     The engine device may further include a controller determining whether to apply electric power to the pulley unit, and the controller may verify operation of a switch of an air conditioner or a state of charge of a battery. When the switch of the air conditioner is operated or when the state of charge of the battery reaches a predetermined capacity of the battery, the controller may control the pulley unit to rotate the clutch pulley. 
     The pulley unit may include a clutch pulley connected to the auxiliary drive system via a belt, a field coil assembly provided inside the clutch pulley and configured to generate electromagnetic force depending on application of electric power, and a disc hub assembly connected to the crankshaft inside the clutch pulley and configured to be engaged with the clutch pulley when the field coil assembly generates electromagnetic force due to application of electric power thereto so that the clutch pulley is rotated by the engine torque. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and other advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a view illustrating an engine device for a vehicle according to an exemplary embodiment of the present disclosure; 
         FIG. 2  is a block diagram of components of the engine device for a vehicle illustrated in  FIG. 1 ; and 
         FIG. 3  is a view illustrating a pulley unit of the engine device for a vehicle according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles. 
     The terminology used herein is for the purpose of describing particular embodiments only 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 terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Throughout the specification, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. In addition, the terms “unit”, “-er”, “-or”, and “module” described in the specification mean units for processing at least one function and operation, and can be implemented by hardware components or software components and combinations thereof. 
     Further, the control logic of the present disclosure may be embodied as non-transitory computer readable media on a computer readable medium containing executable program instructions executed by a processor, controller or the like. Examples of computer readable media include, but are not limited to, ROM, RAM, compact disc (CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart cards and optical data storage devices. The computer readable medium can also be distributed in network coupled computer systems so that the computer readable media is stored and executed in a distributed fashion, e.g., by a telematics server or a Controller Area Network (CAN). 
     Reference will now be made in detail to the preferred embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
       FIG. 1  is a view illustrating an engine device for a vehicle according to an exemplary embodiment of the present disclosure,  FIG. 2  is a block diagram of components of the engine device for a vehicle illustrated in  FIG. 1 , and  FIG. 3  is a view illustrating a pulley unit of the engine device for a vehicle according to the present disclosure. 
     In the following description of the present disclosure, an auxiliary drive system will be described as being configured to receive engine torque via a belt. However, devices that must be operated when an engine operates, for example, a steering hydraulic control system, a cam pulley, or the like, may receive engine torque via separate belts. 
     The present disclosure relates to a device for selectively transferring engine torque to the auxiliary drive system. Because a belt connection structure of an engine is a known technology that is widely used in industrial fields, a pulley unit according to the present disclosure will be mainly described in the following description. 
     As shown in  FIGS. 1 and 2 , the engine device for a vehicle according to the present disclosure may include: a pulley unit  100 , which is connected with a crankshaft C configured to be rotated by engine torque and which is provided with a clutch pulley  120  configured to be selectively rotated by the engine torque depending on whether electric power is applied; and an auxiliary drive system  200 , which is connected with the clutch pulley  120  via a belt B and which is rotated by torque from the clutch pulley  120 . The pulley unit  100  is configured such that the clutch pulley  120  is not rotated when the auxiliary drive system  200  is not rotated, thereby minimizing torque loss attributable to dispersion of the engine torque. The tension of the belt B may be maintained by pulleys provided separately. 
     As such, the present disclosure is characterized in that the engine torque is selectively transferred to the auxiliary drive system  200  via the pulley unit  100  depending on whether the auxiliary drive system  200  needs to rotate. Accordingly, it is possible to minimize loss that may occur due to the transfer of the engine torque to the auxiliary drive system  200  when the auxiliary drive system  200  does not need to rotate. As a result, fuel efficiency is improved, and the engine output is increased. 
     In contrast, in the prior art, because a pulley of a crankshaft and pulleys of an auxiliary drive system are always connected to each other via a belt, all of the pulleys of the auxiliary drive system are rotated when the crankshaft are rotated. Thus, torque loss occurs due to continuous rotation of the auxiliary drive system. 
     In order to solve this problem, the pulley unit  100  according to the present disclosure includes the clutch pulley  120 , which is rotated together with the crankshaft C but selectively transfers torque depending on whether electric power is applied. Accordingly, since the clutch pulley  120  of the pulley unit  100  is not rotated when the auxiliary drive system  200  is not rotated, the engine torque is not transferred to the auxiliary drive system  200 , whereby torque loss is minimized Further, when the auxiliary drive system  200  needs to operate, the clutch pulley  120  of the pulley unit  100  is rotated, and the engine torque is transferred to the auxiliary drive system  200 , whereby the auxiliary drive system  200  operates normally. 
     As such, since the engine torque is selectively transferred to the auxiliary drive system  200  depending on whether the auxiliary drive system  200  needs to rotate, torque loss is minimized, fuel efficiency is improved, and the engine output is increased. 
     A detailed description of the present disclosure will now be made. The auxiliary drive system  200  may include an air-conditioner compressor  240  and an alternator  260 , with a water pump  220  provided separately. 
     That is, in the present disclosure, the devices that constitute the auxiliary drive system  200  are the air-conditioner compressor  240  and the alternator  260 . The air-conditioner compressor  240  and the alternator  260  are provided with pulleys, which are connected to the belt B, so as to be rotated by engine torque. Because the water pump  220  is not connected to the crankshaft C via the belt B, the water pump  220  does not receive engine torque. 
     When an air conditioner, which is included in an air-conditioning system, is not operated, the pulley connected to the air-conditioner compressor  240  does not need to rotate. When the engine of the vehicle is initially started or when it is not necessary to charge a battery, the pulley connected to the alternator  260  does not need to rotate. 
     The water pump  220  needs to operate frequently after the engine is started due to its characteristics. Further, the operating conditions of the water pump  220  vary depending on the temperature of coolant. Thus, the water pump  220  does not receive the engine torque but is operated independently. That is, the water pump  220  may be an electric water pump, which is selectively operated depending on the application of electric power. 
     As described above, in the auxiliary drive system  200 , the pulley of the air-conditioner compressor  240  and the pulley of the alternator  260  are connected to the clutch pulley  120  of the pulley unit  100  via the belt B, and the pulley unit  100  selectively allows the clutch pulley  120  to be rotated by the engine torque depending on whether the auxiliary drive system  200  needs to rotate. Accordingly, it is possible to minimize torque loss of the engine. 
     The water pump  220 , which is embodied by an electric water pump, is electronically controlled in accordance with the engine load and the temperature of coolant. Since the operating conditions of the electric water pump are well known, a detailed description thereof will be omitted. 
     A battery A, which is electrically connected to the alternator  260 , may be a lithium ion battery. 
     According to the present disclosure, the alternator  260  is not always operated, but performs a generation operation when the clutch pulley  120  is rotated by the rotation of the pulley unit  100 . Since the battery A is embodied by a lithium ion battery, which has high charging efficiency and low power loss, the power may be maintained stable even though the alternator  260  is not always operated. If a general battery, which has relatively low charging efficiency, is used, the alternator  260  needs to be operated constantly, which may cause torque loss. 
     Therefore, in the present disclosure, the battery A is embodied by a lithium ion battery, whereby energy charging due to the generation of electric energy of the alternator  260  is achieved efficiently, and thus the extent of operation of the alternator  260  is reduced. 
     The pulley unit  100  is controlled by a controller  300 . The controller  300  determines whether to apply electric power to the pulley unit  100 . To this end, the controller  300  collects information about operation of a switch of the air conditioner or about a state of charge of the battery. When the switch of the air conditioner is operated or when the state of charge of the battery reaches a predetermined capacity of the battery, the pulley unit  100  may be controlled to rotate the clutch pulley  120 . 
     As such, when the switch of the air conditioner is in an off state or when the state of charge of the battery is satisfactory, the controller  300  does not operate the pulley unit  100 , and thus the clutch pulley  120  of the pulley unit  100  is not rotated. The predetermined capacity of the battery, which is stored in advance in the controller  300 , may be set in accordance with the specification of the battery, and may be set to a level at which charging is required due to use of the power stored in the battery. 
     When the controller  300  receives a signal generated by user operation of the switch of the air conditioner or when the state of charge of the battery is insufficient, the controller  300  controls the pulley unit  100  so that the clutch pulley  120  receives the engine torque and rotates. Accordingly, the pulley of the air-conditioner compressor  240  and the pulley of the alternator  260 , which are connected to the clutch pulley  120  via the belt B, are rotated together with the clutch pulley  120 , whereby the air-conditioner compressor  240  and the alternator  260  operate normally. 
     Conversely, upon determining that the air conditioner is turned off or that the state of charge of the battery is sufficient, the controller  300  controls the pulley unit  100  so that the clutch pulley  120  does not receive the engine torque. Accordingly, it is possible to minimize the dispersion of the engine torque to the air-conditioner compressor  240  and to the alternator  260 . As a result, the energy generated by the operation of the engine is used only for the rotation of the crankshaft C, and thus the engine output is increased. 
     As shown in  FIG. 3 , the pulley unit  100  includes: a clutch pulley  120 , which is connected to the auxiliary drive system  200  via the belt B; a field coil assembly  140 , which is provided inside the clutch pulley  120  and which is configured to generate electromagnetic force depending on the application of electric power; and a disc hub assembly  160 , which is connected to the crankshaft C inside the clutch pulley  120  and which is configured to be engaged with the clutch pulley  120  when the field coil assembly  140  generates electromagnetic force due to the application of electric power thereto so that the clutch pulley  120  is rotated by the engine torque. 
     Through this configuration of the pulley unit  100 , when the field coil assembly  140  generates electromagnetic force due to the application of electric power thereto, the disc hub assembly  160  is engaged with the clutch pulley  120 , and consequently, the engine torque is transferred to the clutch pulley  120  via the disc hub assembly  160 . 
     In particular, when electric power is applied to the field coil assembly  140  under the control of the controller  300 , a disc of the disc hub assembly  160  is engaged with the clutch pulley  120  by magnetic induction generated by electromagnetic force of the field coil assembly  140 , and the engine torque is transferred to the clutch pulley  120  and is subsequently transferred to the auxiliary drive system  200  via the belt B connected to the clutch pulley  120 , whereby the auxiliary drive system  200  can rotate. 
     In another example, the pulley unit  100  may include: a housing  180 , which is mounted to an engine case; a clutch pulley  120 , which is rotatably provided around the housing  180 ; a field coil assembly  140 , which is mounted inside the housing  180  and which is configured to generate electromagnetic force depending on the application of electric power; and a disc hub assembly  160 , which includes a hub  161  coupled to the crankshaft C, an inner ring  162  coupled to the hub  161 , an outer ring  164  coupled to the inner ring  162  via a damper  163 , and a disc  165  coupled to the outer ring  164  and configured to be moved toward the clutch pulley  120  by the electromagnetic force. 
     Such a pulley unit  100  is configured based on a clutch hub device, which selectively transfers torque of a drive shaft, such as the crankshaft C, and various known structures other than the above-described structure may be applied to the pulley unit  100 . 
     As is apparent from the above description, according to the engine device for a vehicle configured as described above, the clutch pulley may be rotated together with the crankshaft C or may not be rotated depending on the application of electric power. Therefore, when the auxiliary drive system  200  does not need to rotate, the clutch pulley is prevented from rotating. Accordingly, torque loss attributable to dispersion of torque to the auxiliary drive system is minimized As a result, fuel efficiency is improved, and engine output is increased. 
     Although the preferred embodiment of the present disclosure has been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the disclosure as disclosed in the accompanying claims.