Abstract:
A vehicle having a variable hydraulic pump may include a sun gear that receives a torque from a power source through an input shaft, a ring gear of which an interior circumference is with a distance from an exterior circumference of the sun gear, a planetary gear that is disposed between the interior circumference of the ring gear and the exterior circumference of the sun gear, a carrier that connects with an output shaft, a hydraulic pump that pumps oil through the output shaft that is connected to the carrier, and a motor that is disposed outside the ring gear to selectively rotate the ring gear.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority of Korean Patent Application Number 10-2013-0025571 filed Mar. 11, 2013, the entire contents of which application are incorporated herein for all purposes by this reference. 
       BACKGROUND OF INVENTION 
       [0002]    1. Field of Invention 
         [0003]    The present invention relates to a vehicle having a variable hydraulic pump that variably changes load of hydraulic pump for generating hydraulic pressure that is necessary for an engine or a transmission to reduce energy loss and cost. 
         [0004]    2. Description of Related Art 
         [0005]    Recently, fuel consumption saving art has been researched to reduce CO2, and an ISG (Idle stop and go) system turns off engine in a predetermined stop condition and restarts the engine in a predetermine restart condition. 
         [0006]    The ISG (Idle Stop and Go) system uses information such as vehicle speed, engine rotation speed, coolant temperature, and so on to stop the engine in a predetermined condition and thereafter enables normal driving by restarting engine in a case that the restarting of the engine is demanded by a vehicle condition. 
         [0007]    The ISG system stops an engine to enter into an idle stop condition when an engine is sufficiently warmed up, a coolant temperature is higher than a predetermined value, a condition that a vehicle speed is low or at zero (0), a shifting position of a transmission is neural, and a brake pedal is operated for a predetermined time. 
         [0008]    The ISG device can increase fuel consumption efficiency of a vehicle up to 5 to 15%. Generally, an automatic transmission (AT) has to have a motorized hydraulic pump that supplied oil pressure thereto in an idle stop condition of a vehicle having ISG system. 
         [0009]    Accordingly, the vehicle having an automatic transmission and an ISG system includes a mechanical pump that is disposed in the automatic transmission to be operated by an engine in the ISG none operation condition and generates hydraulic pressure necessary for controlling the automatic transmission and an auxiliary motorized hydraulic pump that is operated in the ISG operation condition to generate hydraulic pressure for the automatic transmission. 
         [0010]    The vehicle having the automatic transmission and the ISG system has two pumps that are a mechanical pump and an auxiliary motorized hydraulic pump, wherein the mechanical pump is operated during the operation of the engine and the auxiliary motorized hydraulic pump is alternatively operated during the none-operation of the engine. 
         [0011]    The vehicle having the automatic transmission and the ISG system has to have two pumps having equal functions, and therefore vehicle cost is increased, vehicle weight is also increased, and the fuel consumption is deteriorated. 
         [0012]    The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention 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 OF INVENTION 
       [0013]    The present invention has been made in an effort to provide a vehicle having a variable hydraulic pump having advantages of minimizing energy lost by hydraulic pump, fuel consumption, and fluctuation of hydraulic pressure by optimally controlling the load of hydraulic pump. 
         [0014]    A vehicle having a variable hydraulic pump according to various aspects of the present invention may include a sun gear that receives a torque from a power source through an input shaft, a ring gear of which an interior circumference is with a distance from an exterior circumference of the sun gear, a planetary gear that is disposed between the interior circumference of the ring gear and the exterior circumference of the sun gear, a carrier that connects with an output shaft, a hydraulic pump that pumps oil through the output shaft that is connected to the carrier, and a motor that is disposed outside the ring gear to selectively rotate the ring gear. 
         [0015]    The vehicle having a variable hydraulic pump may further include a shaft one way clutch that has the input shaft rotate in one direction, and a ring gear one way clutch that has the ring gear rotate in the other direction. The power source may be an internal combustion engine or a motor. 
         [0016]    The vehicle having a variable hydraulic pump may further include a controller that controls the motor depending on a rotation speed of the input shaft such that the hydraulic pump is controlled at a predetermined optimized speed. The motor may be operated at a predetermined rotation speed such that the pump is operated at a minimum rotation speed in an idle stop condition. A compensation value may be applied to a target rotation speed of the hydraulic pump depending on a temperature of the oil, when the power source is operated. 
         [0017]    In a vehicle having a variable hydraulic pump according to various aspects of the present invention, the rotation speed of the hydraulic pump is optimally controlled by a motor in accordance with the rotation speed or driving conditions of an engine to be able to reduce lost energy. Also, the fluctuation of hydraulic pressure that is formed by the hydraulic pump is reduced to be able to improve the stability. Further, compensation value is applied in accordance with oil temperature to be able to safely generate hydraulic pressure and one motor is used to optimally control the load of the hydraulic pump. 
         [0018]    The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a schematic cross-sectional view of an exemplary variable hydraulic pump that is disposed in a vehicle according to the present invention. 
           [0020]      FIG. 2  is a schematic diagram of an exemplary variable hydraulic pump that is disposed in a vehicle according to the present invention. 
           [0021]      FIG. 3  is a schematic diagram showing an operational method of an exemplary variable hydraulic pump that is disposed in a vehicle according to the present invention. 
           [0022]      FIG. 4  is a graph showing a compensation value that varies depending on oil temperature in an exemplary variable hydraulic pump according to the present invention. 
           [0023]      FIG. 5  is a flowchart showing a control method of an exemplary variable hydraulic pump that is disposed in a vehicle according to the present invention. 
           [0024]      FIGS. 6A ,  6 B,  6 C and  6 D are schematic diagrams showing operational conditions of a variable hydraulic pump of a vehicle according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 
         [0026]      FIG. 1  is a schematic cross-sectional view of a variable hydraulic pump that is disposed in a vehicle, and  FIG. 2  is a schematic diagram of a variable hydraulic pump that is disposed in a vehicle according to various embodiments of the present invention. Referring to  FIG. 1  and  FIG. 2 , a variable hydraulic pump of a vehicle includes an engine  100  as a power source, an input shaft  160 , a shaft one way clutch  155 , a sun gear  110 , a planetary gear  105 , a ring gear  140 , a ring gear one way clutch  150 , a motor  145 , a carrier  115 , an output shaft  120 , a hydraulic pump  135 , and a pump housing  165 . Further, the pump housing  165  includes a suction passage  125  through which oil is sucked to the hydraulic pump  135  and a discharge passage  130  through which oil is discharged. 
         [0027]    The torque of the engine  100  is input to the sun gear  110  of the variable hydraulic pump through the input shaft  160 , and the shaft one way clutch  155  is disposed on an exterior circumference of the input shaft  160  to have the input shaft  160  rotate only in one rotation direction. The ring gear one way clutch  150  is disposed on an exterior circumference of the ring gear  140  to have the ring gear  140  rotate only in the other rotation direction. The motor  145  rotates the ring gear  140  in the other rotation direction. 
         [0028]    The torque that is input to the input shaft  160  is transmitted to the sun gear  110 , the planetary gear  105 , the ring gear  140 , the carrier  115 , and the output shaft  120  such that the hydraulic pump  135  pumps oil. When the engine  100  stops its operating, the motor  145  rotates the ring gear  140  to operate the hydraulic pump  135  in a minimum load, and when the engine  100  rotates the input shaft  160  slower than a predetermined velocity, the motor  145  operates the hydraulic pump  135  in a predetermined optimized load. 
         [0029]    Referring to  FIG. 2 , the hydraulic pump  135  can be one of various types of pumps. For example, the hydraulic pump according to various embodiments of the present invention can use trochoid type internal gear. 
         [0030]      FIG. 3  is a schematic diagram showing an operational method of a variable hydraulic pump that is disposed in a vehicle according to various embodiments of the present invention. Referring to  FIG. 3 , Ne denotes a rotation speed if the engine  100  or a rotation speed of the output shaft  120  or a rotation speed of the sun gear  110 , Np denotes a rotation speed of the hydraulic pump  135  or the carrier  115 , Nm denotes a rotation speed of the motor  145  or the ring gear  140 , Zs denotes the number of the gear of the sun gear  110 , and Zr denotes the number of the gear of the ring gear  140 . 
         [0031]    A rotation speed Np of the hydraulic pump  130  is determined by a lever principle, that is, Np can be determined by a rotation speed Ne of the engine  100 , a rotation speed Nm of the motor  145 , the number Zs the gear of the sun gear  110  and the number Zr of the gear of the ring gear  140 . That is, if the rotation speed of the motor  145  is increased in a condition that the rotation speed of the engine  100  is fixed, the rotation speed of the hydraulic pump  135  is increased, and if the rotation speed of the engine  100  is increased in a condition that the rotation speed of the motor  145  is fixed, the rotation speed of the hydraulic pump  135  is increased. 
         [0032]      FIG. 4  is a graph showing a compensation value that varies depending on oil temperature in a variable hydraulic pump according to various embodiments of the present invention. Referring to  FIG. 4 , a horizontal axis denotes oil temperature, and a vertical axis denotes alpha (a) value as a compensation value. The alpha value is used to control the target rotation speed of the hydraulic pump  135 . Referring to  FIG. 5 , the usage method of the compensation value will be further described. 
         [0033]      FIG. 5  is a flowchart showing a control method of a variable hydraulic pump that is disposed in a vehicle according to various embodiments of the present invention. Referring to  FIG. 5 , a control is started in S 500 , and it is determined whether the motor  145  is normal or not in S 510 . The method for determining whether the motor  145  is normal or not refers to disclosed arts and the detailed description thereof will be omitted in the present invention. If it is determined that the motor  145  is abnormal, a fail code is generated in S 570 , and the engine  100  is operated in a predetermined fail mode in S 580 . Here, the motor  145  is not operated, and the hydraulic pump  135  is operated by the engine  100 . 
         [0034]    It is determined whether a vehicle is in an idle stop (ISG) condition in S 520  and S 530 . The idle stop condition (a condition that an engine is stopped in an idle condition) can be determined by a vehicle speed and a brake operating force. For example, the ISG condition is satisfied when a vehicle speed is less than or equal to a predetermined base value (ISG reference value) and a brake operating force is larger than or equal to a predetermined value (ISG reference value). If the vehicle is not in an idle stop condition, S 550  is performed, and if the vehicle is in an idle stop condition, S 540  is performed. 
         [0035]    If it is determined that the engine  100  is stopped and Ne is zero (0) in S 540 , S 590  is performed. The rotation speed (Nm) of the motor  145  is maintained at a predetermined value (N_isg) in S 590 . If it is determined that the rotation speed Ne of the engine  100  is not zero (0) in S 540 , it is determined whether oil temperature is larger than a reference value in S 550 . If it is determined that oil temperature is larger than a reference value, S 560  is performed, and if it is determined that oil temperature is less than a reference value, S 595  is performed. 
         [0036]    A rotation speed (Nm) of the motor  145  is calculated by a controller through a formula −Zs/Zr*(Ne−(Np+α))−(Np+α) in S 560 . And, a rotation speed (Nm) of the motor  145  is calculated by a controller through a formula −Zs/Zr*(Ne−Np)−Np in S 595 . 
         [0037]      FIGS. 6A ,  6 B,  6 C and  6 D are schematic diagrams showing operational conditions of a variable hydraulic pump of a vehicle according to various embodiments of the present invention. 
         [0038]      FIG. 6A  shows that an engine  100  is operated in an idle condition, wherein the rotation speed of the motor  145  is maintained to a relatively high state such that the rotation speed of the hydraulic pump  135  is maintained to a predetermined optimized value. 
         [0039]      FIG. 6B  shows that an engine  100  is operated in a low load condition, wherein the rotation speed of the motor  145  is maintained to a relatively middle state such that the rotation speed of the hydraulic pump  135  is maintained to a predetermined optimized value. 
         [0040]      FIG. 6C  shows that an engine  100  is operated in a high load condition, wherein the rotation speed of the motor  145  is maintained to a relatively low state or not operated such that the rotation speed of the hydraulic pump  135  is maintained to a predetermined optimized value. 
         [0041]      FIG. 6D  shows that an engine  100  is stopped to be operated, wherein the rotation speed of the motor  145  is maintained to an idle state such that the rotation speed of the hydraulic pump  135  is maintained to a predetermined optimized value. 
         [0042]    In various embodiments of the present invention, the motor can be regarded as a stator of a general motor unit and the ring gear can be regarded as a rotor of the motor unit. 
         [0043]    For convenience in explanation and accurate definition in the appended claims, the terms “interior” or “exterior”, and etc. are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. 
         [0044]    The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.