Abstract:
The present invention provides a hybrid vehicle, which has both the function of supplying hydraulic oil to a transmission when the idle operation of an engine is stopped, and the function of providing start force when the engine is cold started, thus reducing space occupied by components, and enhancing assembling productivity due to modularized components.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   The present application is based on, and claims priority from, Korean Application Serial Number 10-2005-0109124, filed on Nov. 15, 2005, the disclosure of which is hereby incorporated by reference herein in its entirety. 
   FIELD OF THE INVENTION 
   The present invention relates to a starter with an electric oil pump for a hybrid vehicle and, more particularly, to a starter with an electric oil pump for a hybrid vehicle, constructed to supply hydraulic oil to a transmission when an engine is started. 
   BACKGROUND OF THE INVENTION 
   A conventional hybrid vehicle is constructed so that an engine and an electric motor are operated in conjunction with an auxiliary machine, respectively. Further, the hybrid vehicle is provided with a starter motor to start the engine, and an electric oil pump to supply hydraulic oil to a transmission. 
   In such a vehicle, the electric motor is referred to as an Integrated Starter Generator (ISG), and has both a starting function and an electricity generating function. The starter motor serves to forcibly rotate a crank shaft when the engine is started. The electric oil pump provides hydraulic oil to the transmission, in addition to a path which supplies hydraulic oil to the transmission by the driving of the engine when the idle operation of the engine is stopped. 
   However, the conventional hybrid vehicle constructed as described above is problematic in that it must be provided with the starter motor which moves the crank shaft when the engine is started, and the electric oil pump which supplies hydraulic oil to the transmission, respectively, so that a large installation space is required, and the starter motor and the electric oil pump must be separately assembled, thus inconveniencing a manufacturer. 
   SUMMARY OF THE INVENTION 
   Embodiments of the present invention provide a hybrid vehicle, which has both the function of supplying hydraulic oil to a transmission when the idle operation of an engine is stopped, and the function of providing start force when the engine is cold started, thus reducing space occupied by components, and enhancing assembling productivity due to modularized components. 
   A hybrid vehicle according to an embodiment of the present invention includes an engine to generate a driving force by combustion of fuel. An auxiliary machine is operated by the driving force generated during the operation of the engine. An integrated starter generator starts the engine using electric power charged when the engine is hot started, produces electric power using the driving force of the engine, and drives the auxiliary machine using the charged electric power when the engine stops idle operation. A belt operates a pulley installed at each of a crank shaft of the engine, an output shaft of the auxiliary machine, and an output shaft of the integrated starter generator. A clutch is installed on the crank shaft, and controls power transmission between the crank shaft and the pulley installed at the crank shaft. An automatic transmission shifts and outputs a driving force generated from the engine according to driving conditions. A starter motor generates a driving force by charged electricity when the engine is cold started, thus starting the engine. An electric oil pump supplies hydraulic oil to the automatic transmission. In this case, the starter motor includes a drive part, a selective engaging part, and an engagement drive part. The drive part is rotated when operating power is applied. The selective engaging part has a pinion which is movably installed on a rotating shaft of the drive part, and engages with a ring gear which is coupled to the crank shaft of the engine, during start. The engagement drive part operates the selective engaging part only when the engine is started, thus forcing the pinion to engage with the ring gear. The electric oil pump shares a single rotating shaft with the starter motor. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the nature and objects of the present invention, reference should be made to the following detailed description with the accompanying drawings, in which: 
       FIG. 1  illustrates the construction of a hybrid vehicle having a starter with an electric oil pump, according to the present invention; and 
       FIG. 2  depicts the detailed construction of the starter with the electric oil pump shown in  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Herein below, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. 
   As shown in  FIGS. 1 and 2 , a vehicle includes an engine  10 , a torque converter  12 , and an automatic transmission  14 . The engine  10  is a power source of the vehicle, and burns an air/fuel mixture, thus generating a driving force. The torque converter  12  amplifies the driving force generated by the engine  10 . The automatic transmission  14  automatically changes the reduction ratio between the maximum reduction ratio and the minimum reduction ratio. 
   The engine  10  is provided with an injector  16  which regulates an amount of fuel injection and a fuel injection period. In the case of an ignition engine, the engine  10  is provided with an ignition plug  18 . The injector  16  and the ignition plug  18  are operated under the control of an Engine Control Unit (ECU). 
   Further, the engine  10  rotates an input shaft of the torque converter  12  via a crank shaft  11 . An output shaft of the torque converter  12  rotates an input shaft of the automatic transmission  14 . An output shaft of the automatic transmission  14  rotates a propeller shaft  20 . Thereby, wheels  26  are rotated through a differential gear  22  and an axle  24 . 
   The crank shaft  11  of the engine  10  is coupled via a belt  30  to an auxiliary machine  28 , such as a power steering oil pump, a compressor for an air conditioner, and a water pump, thus transmitting power to the auxiliary machine  28 . An ISG  32  is coupled to the auxiliary machine  28  to generate a driving force using electricity which is charged in a battery to transmit power when the idle operation of the engine  10  has stopped. 
   In this case, the ISG  32  provides start force when the engine  10  is hot started, and provides driving force to the auxiliary machine  28  in place of the engine  10  when the idle operation of the engine  10  has stopped. 
   To this end, a pulley P is installed on each of the crank shaft  11  of the engine  10 , the output shaft of the auxiliary machine  28 , and an output shaft  33  of the ISG  32  so that they are operated in conjunction with each other via the belt  30 . Further, a clutch C is installed on the crank shaft  11  to control power transmitted between the crank shaft  11  and the pulley P provided on the crank shaft  11 . The clutch C comprises an electronic or hydraulic multiple disc clutch, the engagement and disengagement of which are controlled by the ECU that will be described below in detail. 
   Further, the ISG  32  is connected to a large-capacity 36V battery  36  via an inverter  34 . A DC/DC converter  38  is installed between the inverter  34  and the large-capacity battery  36 . The DC/DC converter  38  is connected to a small-capacity 12V battery  40 . 
   In this case, under the control of a motor control unit (MCU), the inverter  34  supplies electricity required to drive the ISG  32  from the large-capacity battery  36 , and in addition, supplies electric power generated by the ISG  32  to the large-capacity battery  36 , thus charging the large-capacity battery  36 . 
   Further, the DC/DC converter  38  decreases the voltage of power which is produced by the ISG  32 , thus charging the small-capacity battery  40 . When necessary, the DC/DC converter  38  boosts the voltage of power charged in the small-capacity battery  40 , thus providing the boosted power to the ISG  32 . 
   The ECU and the MCU are controlled by a hybrid control unit (HCU). Thus, the HCU is connected to a sensing means S which detects and inputs various operation states of the vehicle. The sensing means S comprises various kinds of sensors, which detect the speed, acceleration, and braking extent of a vehicle, the inclination of a road surface, a battery charging state, etc. 
   Meanwhile, the engine  10  is provided with a starter motor  42  which starts the engine  10  when the engine  10  is cold started. Further, the engine  10  is provided with an electric oil pump  44  which supplies hydraulic oil to the automatic transmission  14 , when the idle operation of the engine  10  is stopped. 
   In this case, the starter motor  42  and the electric oil pump  44  are integrated into a single structure which shares a single rotating shaft  46 . In other words, they constitute an integrated starter having the electric oil pump. 
   To this end, the starter motor  42  includes a drive part  48 , a selective engaging part  52 , and an engagement drive part  54 . The drive part  48  is rotated as operating power is applied. The selective engaging part  52  is provided with a pinion  50  which is movably mounted on the rotating shaft  46  of the drive part  48 , and selectively engages with a ring gear  11   a  mounted to the crank shaft  11  of the engine  10  during a start. The engagement drive part  54  operates the selective engaging part  52  only when the engine  10  is started, so that the pinion  50  engages with the ring gear  11   a.    
   In this case, the drive part  48  includes a rotor  48   a , a stator  48   b , a brush  48   c , and a rectifier  48   c . The rotor  48   a  is installed on the rotating shaft  46 . The stator  48   b , comprising a permanent magnet, is disposed around the rotor  48   a . The brush  48   c  supplies direct power to the rotor  48   a . The rectifier  48   d  intermittently supplies direct power from the brush  48   c  to the rotor  48   a.    
   The selective engaging part  52  includes a plunger  52   a  and an overrunning clutch  52   b . The plunger  52   a  axially moves the pinion  50  on the rotating shaft  46 . The overrunning clutch  52   b  restrictively transmits the driving force from the rotating shaft  46  to the pinion  50 . 
   Further, the engagement drive part  54  includes a lever  54   a  and a solenoid actuator  54   b . The lever  54   a  axially moves the plunger  52   a  relative to the rotating shaft  46 . The solenoid actuator  54   b  applies actuating force to the lever  54   a . A pull-in coil  54   b - 1  and a hold-in coil  54   b - 2  are wound around the solenoid actuator  54   b  to provide electromagnetic force. 
   An internal gear  44   a  constituting the electric oil pump  44  is secured to an end of the rotating shaft  46 , and a external gear  44   b  is installed around the internal gear  44   a  in such a way as to be eccentric to the internal gear  44   a . The internal gear  44   a  and the external gear  44   b  are accommodated in a housing  44   c  having a predetermined sealed space therein. An inlet port  44   d  and an outlet port  44   e  are formed in the housing  44   c  to permit the suction and discharge of the hydraulic oil. 
   Moreover, the inlet port  44   d  and the outlet port  44   e  are coupled via corresponding hydraulic pipes  56  to an oil fan of the automatic transmission  14 . A strainer  58  is installed on the hydraulic pipe  56  to remove impurities contained in the hydraulic oil. 
   The operation of the present invention will be described below in detail. 
   First, when the engine  10  is cold started, the starter motor  42  is operated, thus driving the ring gear  11   a . At this time, the crank shaft  11  of the engine  10  is operated, thus driving the auxiliary machine  28  via the belt  30 . In this case, the clutch C is engaged. 
   Subsequently, when the engine  10  has been started and normal driving is performed, the ECU appropriately operates the engine  10  according to a driver&#39;s intentions or the driving conditions. 
   Meanwhile, if the sensing means S connected to the HCU determines that the idle operation of the engine  10  is stopped during the drive of a vehicle, the HCU controls the ECU, thus stopping the supply of fuel through the injector  16 . Thereby, the engine  10  is stopped. 
   In this case, the standard of determination regarding the stop of the idle operation of the engine  10  is as follows. That is, the present charging state of the battery must exceed a preset value (about 55%), the temperature of coolant must exceed a preset value (about 70° C.), the acceleration pedal must not be pressed, a vehicle speed must be 8 km/hr or less, the brake must be being operated, and the current gear must be a drive gear. 
   That is, when the HCU determines that all of the above-mentioned conditions are satisfied, the injection of fuel through the injector  16  is stopped, so that the engine  10  is switched into a stop mode. Thus, if the injection of fuel through the injector  16  is stopped when the engine  10  stops idle operation, the unnecessary use of fuel is prevented, so that fuel consumption efficiency is enhanced. 
   At this time, the HCU controls the MCU, thus driving the ISG  32 . As the ISG  32  is driven, power is generated. The power is applied to the auxiliary machine  28 , so that normal operation is executed. In this case, the clutch C is disengaged, thus limiting the rotation of the crank shaft  11  due to the drive of the ISG  32 . 
   In addition, the HCU operates the drive part  48  of the starter motor  42 , thus driving the electric oil pump  44  which shares the rotating shaft  46  with the starter motor  42 . Thereby, the electric oil pump  44  continuously supplies hydraulic oil to the automatic transmission  14 , and prepares for the re-start of the engine  10 . At this time, the engagement drive part  54  of the starter motor  42  is not operated, so that the ring gear  11   a  is not started despite the drive of the starter motor  42 . 
   Further, when the sensing means S connected to the HCU determines that the engine  10  is re-started, the HCU operates the ISG  32 , and starts the crank shaft  11  of the engine  10  via the belt  30 . At this time, since the hydraulic oil is sufficiently supplied to the automatic transmission  14  due to the driving of the electric oil pump  44 , the automatic transmission  14  can be smoothly operated. In this case, the engagement drive part  54  of the starter motor  42  is not operated, so that the ring gear  11   a  is not started by the driving of the starter motor  42 . 
   Moreover, when the engine  10  is re-started, the driving of the electric oil pump  44  is conducted only at an initial starting point. When the engine  10  is normally operated, the electric oil pump  44  is not driven but a mechanical pump provided in the automatic transmission  14  is operated, thus supplying the hydraulic oil. 
   Meanwhile, when the engine  10  is cold started, operating power is applied to the engagement drive part  54  of the electric oil pump  44 . Thereby, the selective engaging part  52  of the electric oil pump  44  is operated, so that the pinion  50  drives the ring gear  11   a , thus starting the engine  10 . 
   In this case, the electric oil pump  44  which shares the rotating shaft  46  with the starter motor  42  allows the hydraulic oil to be smoothly supplied to the automatic transmission  14 . 
   As apparent from the foregoing, the present invention provides a starter with an electric oil pump for a hybrid vehicle, which drives an auxiliary machine and prevents the injection of fuel through an integrated starter generator, when the idle operation of an engine is stopped during the driving of the vehicle, thus increasing fuel consumption efficiency, and which is constructed so that the electric oil pump is operated due to driving of the starter motor that shares a rotating shaft with the electric oil pump, thus smoothly supplying hydraulic oil to an automatic transmission. 
   If the engine is re-started, that is, hot started, the start of the engine is promoted by the integrated starter generator. Conversely, if the engine is cold started, the engine is started by the driving of a ring gear due to the driving of the starter motor.