Abstract:
The oil pump for a vehicle may include a housing forming an outer wall of the oil pump, an outer ring to control a pumping volume of an oil, a first chamber for storing a pumped oil and connected to an engine to supply the oil to the engine, a second chamber selectively communicated to the first chamber to store the pumped oil, a rotor moving along a radial direction to pump the oil and rotating at the same time, an elastic member for controlling an operation pressure of the oil to maintain a working moment of the outer ring, and a solenoid valve for selectively communicating the first chamber with the second chamber.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority of Korean Patent Application Number 10-2012-0157472 filed Dec. 28, 2012, 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 an oil pump for a vehicle. More particularly, the present invention relates to an oil pump for a vehicle using an on/off solenoid valve. 
         [0004]    2. Description of Related Art 
         [0005]    Generally, an oil pump for a vehicle is operated by a torque of a crankshaft or a camshaft transmitted through a chain or a gear. The oil pump draws an oil in an oil pan, boosts pressure of the drawn oil, and supplies lubrication oil to each frictional members of an engine. Performance of the pump is appeared by an amount and pressure of supplied oil. In addition, the oil pump is divided into an external gear type and an internal gear type. In the external gear type, an involute tooth is often used, and in the internal gear type, a trochoid curve is often used. 
         [0006]    A regulator is provided at the oil pump so as to maintain hydraulic pressure of a lubrication portion within a predetermined range. In addition, viscosity of oil varies according to the oil temperature, and the amount of supplied oil is increased in proportion to engine speed. Therefore, the regulator appropriately controls hydraulic pressure for lubricating by temperature. A regulator chamber is provided at the regulator for storing oil. 
         [0007]    The regulator chamber may be provided with at least a solenoid valve provided for controlling the amount and pressure of oil transmitted from the oil pump to an engine. The solenoid valve is adapted to selectively communicate a regulator chamber and other regulator chamber. 
         [0008]    However, in case that a proportional control solenoid valve is used as the solenoid valve, the composition of the oil pump may be complex and the manufacturing cost of the oil pump may be increased. In addition, difficulty of control is excessively increased according to it is required that the proportional control solenoid valve is precisely controlled. Meanwhile, it may be difficult that durability of exquisite components included at the proportional control solenoid valve is ensured. 
         [0009]    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 
       [0010]    The present invention has been made in an effort to provide an oil pump for a vehicle having advantages of having simply configuration. In addition, the present invention has been made in an effort to provide an oil pump for a vehicle having advantages of controlling an amount and pressure of supplied oil easily. 
         [0011]    The oil pump for a vehicle according to various aspects of the present invention may include a housing forming an outer wall of the oil pump, an outer ring to control a pumping volume of an oil, a first chamber for storing a pumped oil and connected to an engine to supply the oil to the engine, a second chamber selectively communicated to the first chamber to store the pumped oil, a rotor moving along a radial direction to pump the oil and rotating at the same time, an elastic member for controlling an operation pressure to maintain a working moment of the outer ring, and a solenoid valve for selectively communicating the first chamber with the second chamber. 
         [0012]    The solenoid valve may be an on/off solenoid valve which is operated to open/close in 2 steps. 
         [0013]    The oil pump may further include an electronic control unit receiving a rotation speed of the engine and comparing the rotation speed of the engine with a predetermined rotation speed, and a temperature sensor sensing an oil temperature in the engine and transmitting information about the oil temperature to the electronic control unit, wherein the electronic control unit controls the solenoid valve to open/close according to the rotation speed of the engine and the oil temperature sensed by the temperature sensor. 
         [0014]    The solenoid valve may be respectively controlled on each section of at least two sections that are divided according to the oil temperature in the engine. 
         [0015]    The rotation speed of the engine for operating the solenoid valve may be determined on each section of the at least two sections that are divided according to the oil temperature in the engine. 
         [0016]    The solenoid valve may maintain opened if the rotation speed of the engine is slower than the predetermined rotation speed of the engine, and is closed if the rotation speed of the engine reaches the predetermined rotation speed of the engine. 
         [0017]    The predetermined rotation speed of the engine for closing the solenoid valve may be relatively high on a section when the oil temperature in the engine is relatively low, and the predetermined rotation speed of the engine for closing the solenoid valve may be relatively low on a section when the oil temperature in the engine is relatively high. 
         [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 diagram of an exemplary oil pump for a vehicle according to the present invention. 
           [0020]      FIG. 2  is a graph illustrating a relationship between rotation speed of an engine and pressure of supplied oil from an exemplary oil pump for a vehicle according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    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. 
         [0022]      FIG. 1  is a schematic diagram of an oil pump for a vehicle according to various embodiments of the present invention. As shown in  FIG. 1 , an oil pump for a vehicle  1  includes a housing  10 , an outer ring  11 , a first chamber  14 , a second chamber  15 , a rotor  12 , a vane  18 , an inner ring  19 , an elastic member  13 , and a solenoid valve  50 . 
         [0023]    The housing  10  is a case forming an outer wall of the oil pump  1 . One end of the outer ring  11  is rotatably connected to the housing  10  by a pivot pin  3 . In addition, pumping volume of the oil pump  1  is determined according to the outer ring  11  rotates around the pivot pin  3 . 
         [0024]    The first and second chambers  14  and  15  are spaces for storing oil pumped by the oil pump  1 . In addition, the first and second chambers  14  and  15  are adapted to control hydraulic pressure of the oil pump  1  and are formed between the housing  10  and the outer ring  11 . 
         [0025]    The rotor  12  rotates and moves in a radial direction when the oil pump  1  is operated by rotation of a crankshaft or a camshaft. Thus, oil is pumped by operation of the rotor  12 . The vane  18  is rotated by rotation of the rotor  12 . In addition, the pumping volume of the oil pump  1  may be varied according to the number of vanes  18 . 
         [0026]    The inner ring  19  is disposed at the inside of the outer ring  11 , and the radius of the inner ring  19  is shorter than the radius of the outer ring  11 . In addition, the inner ring  19  contacts one end of the vane  18 ; the other end of the vane  18  and the interior circumference of the outer ring  11  constantly contact each other. 
         [0027]    The elastic member  13  is disposed at one side of the outer ring  11 . In addition, the elastic member  13  controls operation pressure for stably maintaining working moment of the outer ring  11 . 
         [0028]    Some components of the oil pump  1  including the housing  10 , the outer ring  11 , the first chamber  14 , the second chamber  15 , the rotor  12 , the vane  18 , the inner ring  19 , and the elastic member  13  are known in the art such that a detailed description thereof will be omitted. 
         [0029]    The solenoid valve  50  is provided to selectively communicate the first chamber  14  with the second chamber  15 . In addition, an oil hole  16  and an oil passage  17  are formed at the housing  10 . 
         [0030]    The oil hole  16  is a hole which is adapted to communicate the first chamber  14  with the solenoid valve  50 . In addition, the oil passage  17  is a passage which is adapted to communicate the solenoid valve  50  with the second chamber  15 . That is, the solenoid valve  50  is selectively opened or closed between the oil hole  16  and the oil passage  17  so as to selectively communicate the oil hole  16  with the oil passage  17 . 
         [0031]    Herein, the solenoid valve  50  is an on/off solenoid valve which is operated to open and close in 2 steps. For example, the solenoid valve  50  is operated to open when power is supplied and close when power is not supplied, or is operated to close when power is supplied and open when power is not supplied. 
         [0032]    The oil pump  1  according to various embodiments of the present invention further includes a temperature sensor  30  and an electronic control unit  20 , and is connected with an engine  40 . In addition, the oil pump  1  supplies oil to the engine  40 . Herein, the engine  40  is connected with the oil pump  1  so as to receive oil from the first chamber  14 . 
         [0033]    The temperature sensor  30  is connected with the engine  40  and the solenoid valve  50 , and senses temperature of oil flowed into the engine  40 . 
         [0034]    The electronic control unit  20  controls open/close of the solenoid valve  50 . In addition, the electronic control unit  20  is connected with the temperature sensor  30  so as to receive information about oil temperature from the temperature sensor  30 . The electronic control unit  20  controls the solenoid valve  50  according to information about oil temperature received from the temperature sensor  30  and rotation speed of the engine  40 . Herein, the electronic control unit  20  may be a general electronic control unit (ECU: electronic control unit) supervising various controls for electronic devices of a vehicle. 
         [0035]    The method detecting rotation speed of the engine  40  and the method that the electronic control unit  20  holds information about the detected rotation speed of the engine  40  are well-known to a person of ordinary skill in the art such that a detailed description thereof will be omitted. 
         [0036]    Hereinafter, an operation of the oil pump  1  based on rotation speed of the engine  40  will be described in detail. 
         [0037]    The solenoid valve  50  is opened in a low speed section of the engine  40 . That is, the first chamber  14  and the second chamber  15  are communicated with each other. Herein, the low speed section of the engine  40  refers to a case when rotation speed of the engine  40  is slower than or equal to a set speed, and the set speed can be predetermined. Further, oil fills into the first chamber  14  and the second chamber  15  when the solenoid valve  50  is opened in the low speed section of the engine  40 . 
         [0038]    The oil pump  1  is controlled on each section, separated with a primary control section and a secondary control section as rotation speed of the engine  40  is increased. In addition, the electronic control unit  20  determines rotation speed of the engine  40 , and controls the solenoid valve  50 . 
         [0039]    The solenoid valve  50  is opened on the primary control section. An amount and pressure of oil discharged from the oil pump  1  are increased as rotation speed of the engine  40  is increased, and the pressure of oil imposes on the first chamber  14  and the second chamber  15 . In addition, the pressure of oil imposing on the first chamber  14  and the second chamber  15  is increased over the pressure predetermined at the elastic member  13 . Further, the outer ring  11  rotates anticlockwise in the drawing by the pressure of oil increased over the predetermined pressure of the elastic member  13 . Therefore, the eccentricity amount of the outer ring  11  with respect to the center of the oil pump  1  is becoming reduced, and the amount of oil discharged from the oil pump  1  is becoming decreased. Herein, fuel consumption can be improved as the amount of oil discharged from the oil pump  1  is decreased. 
         [0040]    The secondary control section is a section when rotation speed of the engine  40  becomes faster compared to the primary control section. The solenoid valve  50  is closed on the secondary control section. That is, oil via the oil hole  16 , the solenoid valve  50 , and the oil passage  17  is not flowed into the second chamber  15 . In addition, pressure of oil imposing on only the first chamber  14  is lower than the pressure predetermined at the elastic member  13 . Therefore, the outer ring  11  rotates clockwise in the drawing, and the eccentricity amount of the outer ring  11  with respect to the center of the oil pump  1  is becoming increased. That is, the amount of oil discharged from the oil pump  1  is increased, and oil pressure in the engine  40  is becoming higher. 
         [0041]    The amount of oil discharged from the oil pump  1  is increased in proportion to rotation speed of the engine  40  as rotation speed of the engine  40  becomes faster in a period after the secondary variable. 
         [0042]    Meanwhile, the operation of the oil pump  1  is reversely performed when the engine  40  speed is becoming slow. That is, while the operations of the oil pump  1  according to the low speed section of the engine  40 , the primary control section, the secondary control section, and the period after the secondary variable are sequentially performed when the engine  40  speed is becoming fast, the operations of the oil pump  1  according to the period after the secondary variable, the secondary control section, the primary control section, and the low speed section of the engine the oil pump  1  are sequentially performed when the engine  40  speed is becoming slow. 
         [0043]      FIG. 2  is a graph illustrating a relationship between rotation speed of an engine and pressure of supplied oil from an oil pump for a vehicle according to various embodiments of the present invention. As shown in  FIG. 2 , there is a section in which oil pressure is excessively high, according to an ordinary curved line L 1  which shows a correlation of the supplied oil pressure and rotation speed of the engine  40 . Herein, the supplied oil pressure is pressure of oil supplied from the oil pump  1  to the engine  40 . 
         [0044]    The supplied oil pressure of the oil pump  1  can be optimally controlled according to a graph L 2  about the supplied oil pressure and rotation speed of the engine  40  by the operation of the oil pump  1 . Particularly, in a period when rotation speed of the engine  40  is faster compared to the primary control section, the difference between the graph L 2  of the present invention and the ordinary curved line L 1  is definite or substantial. Herein, fuel consumption may be improved as a result of the difference between the graph L 2  of the present invention and the ordinary curved line L 1 . 
         [0045]    The starting point Pf of the primary control section and the starting point Ps of the secondary control section are determined according to the predetermined rotation speed of the engine  40 , and the rotation speed of the engine  40  for determining start of the primary control section and secondary control section is predetermined. In addition, fuel consumption is improved as the rotation speed of the engine  40  for determining start of the secondary control section is becoming past. However, the state that the amount of oil in the engine  40  is not sufficient may be long as the gap between the rotation speeds of the engine  40  for starting the primary control section and the secondary control section are is large. That is, durability of the engine  40  may be deteriorated. 
         [0046]    Therefore, one may predetermine the rotation speed of the engine  40  for determining start of the primary control section and secondary control section by considering durability and fuel consumption of the engine  40 . 
         [0047]    The electronic control unit  20  possesses logic controlling the solenoid valve  50  according to temperature of oil. In addition, the rotation speed of the engine  40  for starting the secondary control section is changed according to temperature of oil. The electronic control unit  20  controls the solenoid valve  50  by dividing state of the engine low temperature and state of the engine high temperature. 
         [0048]    The state of the engine low temperature is a case that oil in the engine  40  has low temperature, and the state of the engine low temperature may be the state that oil temperature of the engine  40  is lower than 80° C. In addition, oil pressure is naturally becoming high as oil temperature is low on the state of the engine low temperature. Further, thermal load of the components comprising the engine  40  is relatively low on the state of the engine low temperature. 
         [0049]    The rotation speed of the engine  40  for starting the secondary control section may be determined to be a relatively high speed on the state of the engine low temperature. For example, the rotation speed of the engine  40  for starting the secondary control section is determined to be 3000 rpm on the state of the engine low temperature. 
         [0050]    The state of the engine high temperature is a case that oil in the engine  40  has a high temperature, and the state of the engine high temperature may be the state that oil temperature of the engine  40  is higher than or equal to 80° C. In addition, oil pressure is naturally becoming low as oil temperature is relatively high compared to the state of the engine low temperature on the state of the engine high temperature. Further, thermal load of the components comprising the engine  40  is relatively high on the state of the engine high temperature. 
         [0051]    The rotation speed of the engine  40  for starting the secondary control section may be determined to be a relatively low speed on the state of the engine low temperature. For example, the rotation speed of the engine  40  for starting the secondary control section is determined to 2000 rpm on the state of the engine high temperature. 
         [0052]    Meanwhile, sections for determining oil temperature are further subdivided, and the rotation speed of the engine  40  for starting the secondary control section may be predetermined on the each subdivided section. For example, sections for determining oil temperature may be divided to a section that oil temperature of the engine  40  is lower than 50° C., a section that oil temperature of the engine  40  is higher than or equal to 50° C. and lower than 100° C., and a section that oil temperature of the engine  40  is higher than or equal to 100° C., and the rotation speed of the engine  40  for starting the secondary control section may be respectively determined to 3000 rpm, 2500 rpm, and 2000 rpm on the each section. 
         [0053]    As described above, if the section for determining oil temperature and the rotation speed of the engine  40  for starting the secondary control section on the each section are determined, the rotation speed of the engine  40  for starting the secondary control section can be predetermined as high as possible and fuel consumption can be improved and, in some cases, substantially. Meanwhile, sections for determining oil temperature may be further subdivided. 
         [0054]    According to various embodiments of the present invention, it can be easy for controlling an amount and pressure of supplied oil by using the on/off solenoid valve  50  so as to selectively communicate the first chamber  14  with the second chamber  15 . In addition, the configuration of the oil pump  1  can be simple, the manufacturing cost of the oil pump  1  can be reduced, and simultaneously, the durability of the oil pump  1  can be improved by using the on/off solenoid valve  50  having simple control method, requiring the temperature sensor  30 , and removing a pressure sensor. 
         [0055]    For convenience in explanation and accurate definition in the appended claims, the terms “inside” or “outside”, and etc. are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. 
         [0056]    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.