Patent Publication Number: US-11022134-B2

Title: Oil pump of vehicle having inner ring

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2018-0057186, filed on May 18, 2018, which is incorporated herein by reference in its entirety. 
     FIELD 
     The present disclosure relates to an oil pump for pressurizing engine oil of a vehicle. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     An engine mounted on a vehicle circulates engine oil for reducing the friction of each moving part and for cooling. The engine oil is pressurized by an oil pump mounted inside the engine and supplied to the lubrication parts. 
     As a prior art, an oil pump structure is shown in  FIG. 1 . The oil pump  110  includes a housing  111  in which a space is formed, a rotor  112  which is eccentrically rotated inside the housing  111 , and vanes  113  which are slidable in the radial direction of the rotor  112  and installed at intervals along the circumferential direction of the rotor  112 . Since the vanes  113  are installed so that the front ends of the vanes  113  are in close contact with the inner surface of the housing  111 , the oil is compressed by the volume change of the space between the inner surface of the housing  111  and the vanes  113  adjacent to the outer surface of the rotor  112  and each other when the rotor  112  rotates. 
     However, in the oil pump  110  according to the prior art as described above, since the vanes  113  are rotated by the rotor  112  and simultaneously performs a sliding motion with respect to the rotor  112 , it is found that the moving parts of the oil pump  110  are abruptly abraded when the rotation speed of the oil pump  110  is increased. 
     The inner surface of the housing  111  is nitriding-treated, the vane  113  is made of tool steel, and the outer surface of the rotor  112  is also steam-treated. 
     In recent years, the engine has been upgraded to high performance, so that the oil pump  110  is often operated under severe conditions, thereby promoting abrasion. 
     The foregoing is intended merely to aid in the understanding of the background of the present disclosure, and is not intended to mean that the present disclosure falls within the purview of the related art that is already known to those skilled. The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure, and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. 
     SUMMARY 
     The present disclosure provides an oil pump having an inner ring in which the material of a housing is replaced by a lightweight material, and the rotatable inner ring is provided at an inner surface of the housing to be contacted with vanes. 
     An oil pump according to a form of the present disclosure may include a housing in which a space is formed, a rotor installed to be rotatable in an eccentric position on the housing and having vanes mounted along a circumferential direction to be protruded and retracted in a radial direction of the housing, and an inner ring fitted to an inner surface of the housing and rotated along the rotor when the rotor rotates. The housing is formed of a material harder than the inner ring, and oil for lubrication is provided between the housing and the inner ring. 
     The housing may be made of synthetic resin material. In particular, the housing may be made of thermosetting phenolic resin material. 
     According to other form of the present disclosure, the housing may be made of a light metal having a specific gravity lower than that of steel. In particular, the housing may be made of aluminum or magnesium. 
     The inner ring may be made of metal material. In particular, the inner ring may be made of the same material as the vane. Accordingly, the inner ring may be made of bearing steel or tool steel. 
     According to further aspect of the present disclosure, at least one of an outer circumference surface of the inner ring and an inner surface of the housing may be formed with at least one groove for accommodating oil between the inner ring and the housing. 
     The groove may be formed on the inner surface of the housing as a first groove along the circumference of the housing. 
     The groove may be formed on the outer circumference surface of the inner ring as a second groove along the circumference of the inner ring. 
     The housing may be provided with at least one oil supply hole for supplying oil between the inner surface of the housing and the inner ring. 
     The outer surface of the housing may be provided with at least one pocket formed concavely from the outside of the housing to the inner surface of the housing. The pockets may be formed along the circumference direction and the height direction of the housing. 
     In accordance with the form of the present disclosure, the oil pump includes the housing made of synthetic resin material so that it can be lightweight. Furthermore, the inner surface of the housing is contacted to the inner ring having excellent abrasion resistance, thereby improving abrasion resistance. 
     In addition, since the housing is made of synthetic resin material, it is possible to form the housing shapes as desired to reduce Noise, Vibration and Harshness (NVH). For example, pockets on the outer surface of the housing can be easily formed. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which: 
         FIG. 1  is a plane view of an oil pump according to a prior art; 
         FIG. 2  is a plan view showing an oil pump with an inner ring according to an exemplary form of the present disclosure; 
         FIG. 3  is an exploded perspective view of a housing and an inner ring in the oil pump according to the exemplary form of the present disclosure; 
         FIG. 4  is a partially cut-away perspective view of the oil pump according to the exemplary form of the present disclosure; and 
         FIG. 5  is a perspective view of a groove with a spiral shape formed in a housing of an oil pump according to another exemplary form of the present disclosure. 
     
    
    
     The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     Referring to  FIG. 2 , an oil pump  10  having an inner ring  14  according to the present disclosure may include a housing  11  in which a space is formed, a rotor  12  being installed to be rotatable in an eccentric position on the housing  11  and having vanes  13  mounted along a circumference direction to be protruded and retracted in a radial direction of the housing  11 , and the inner ring  14  which is fitted to an inner surface of the housing  11  and rotates along the rotor  12  when the rotor  12  rotates. The housing  11  may be formed of a material harder than the inner ring  14 , and oil for lubrication may be accommodated between the housing  11  and the inner ring  14 . 
     The space may be formed in the housing  11 . Constituent elements described below may be provided in the space of the housing  11 . 
     The rotor  12  may be installed to be rotatable in an eccentrically located position on the housing  11  and have the vane  13  mounted along a circumference direction to be protruded and retracted in a radial direction of the housing  11 . 
     The inner ring  14  may be fitted to the inner surface of the housing  11 . The inner ring  14  may rotate along the rotor  12  when the rotor  12  rotates. The inner ring  14  may be contact with the rotating vane  13  and formed into a cylinder shape to be fitted to the inner surface of the housing  11 . 
     As shown in  FIG. 2 , when the rotor  12  rotates, the inner ring  14  may rotate in the same direction as the vane  13 . Since the inner ring  14  rotates along the vane  13  when the vane  13  rotates, the inner ring  14  rotates at a later rotation speed than the rotor  12 . 
     The inner ring  14  and the housing  11  may be the duality structure, so that the fixed housing  11  may be formed of lightweight material and the inner ring  14  directly contacting with the rotating vane  13  may be formed of a material having a higher strength than the housing  11 . More specifically, the housing  11  may be formed of synthetic resin or light metal material, and the housing  11  may be made of thermosetting phenolic resin material in synthetic resin and also, a light metal having a specific gravity lower than that of steel, for example, aluminum or magnesium. 
     The inner ring  14  may be made of material that is stronger than the housing  11 , for example steel. Preferably, the inner ring  14  may made of bearing steel or tool steel that is the same material as the vane  13  because the vane  13  may also be made of bearing steel or tool steel. The bearing steel and tool steel have excellent abrasion resistance, which can reduce the abrasion between the vane  13  and the inner ring  14  contacted with each other. 
     Accordingly, since the housing  11  is made of a lightweight material and the inner ring  14  contacting the vane  13  is made of a high-strength material, the weight of the oil pump  10  can be reduced and fuel consumption can be improved. 
     When the rotor  12  rotates with the inner ring  14  together, lubrication is desired between the housing  11  and the inner ring  14 . For this purpose, an oil film is formed to contain oil between the housing  11  and the inner ring  14 . 
     Particularly, in  FIG. 3 , at least one first groove  11   b  is formed on the inner surface of the housing  11  along a height direction H and at least one second groove  14   a  is formed on an outer circumference surface of the inner ring  14  along the height direction H. When the oil pump  10  is assembled according to the present disclosure, at least one of the first groove  11   b  in the housing  11  and second groove  14   a  in the inner ring  14  may be formed for receiving oil. Since the oil is provided inside each of the grooves  11   b  and  14   a , friction between the inner ring  14  and the housing  11  is reduced by the oil while the inner ring  14  rotates in the housing  11 . 
     For example, as shown in  FIG. 3 , the first groove  11   b  may be formed on the inner surface of the housing  11 . The first groove  11   b  may be formed along the circumference direction of the housing  11  at a predetermined depth. In  FIG. 3 , a plurality of the first grooves  11   b  in the housing  11  may be formed along the height direction H of the housing  11 . 
     On the other hand, the second groove  14   a  may also be formed on the outer circumference surface of the inner ring  14 . A plurality of second grooves  14   a  in the inner ring  14  may also be formed along the height direction H of the inner ring  14 . 
     The housing  11  may be provided with at least one oil supply hole  11   a  for supplying oil desired for lubrication between the housing  11  and the inner ring  14 . The oil supply holes  11   a  may be formed through the wall of the housing  11  so that oil is supplied from the outside of the housing  11  to the inner surface of the housing  11  for lubricating between the housing  11  and the inner ring  14 . 
     The oil may also be supplied through the surface where the oil pump  10  is assembled.  FIG. 4  shows the area where the oil is supplied for the lubrication of the oil pump  10  by arrows. The oil may be supplied through the oil supply hole  11   a  (solid line in  FIG. 4 ) and also be supplied through the surface on which the oil pump  10  is assembled (dotted arrow in  FIG. 4 ). 
     On the outer surface of the housing  11 , at least one pocket  11   c  may be formed concavely from the outer surface of the housing  11  along the circumference direction and the height direction H of the housing  11 . 
     The pockets  11   c  are configured for serving to buffer the pressure wave generated by the oil pressurized by and discharged from the oil pump  10  during operation of the oil pump  10 . These pockets  11   c  may be formed in the housing  11  along the circumference direction and the height direction H of the housing  11  for buffering the pressure wave generated when the pressurized oil is discharged from the oil pump  10 , thereby improving NVH (Noise, Vibration and Harshness) performance. 
       FIG. 5  shows an oil pump housing having an inner ring (not shown) according to another exemplary form of the present disclosure. 
     The present exemplary form has the same configuration as the oil pump described above except that another groove  21   b  of the housing  21  is formed in a different shape. As shown in  FIG. 5 , the groove  21   b  formed in the housing  21  may be formed in a spiral pattern along the inner surface of the housing  21  to supply oil between the housing  21  and the inner ring (not shown). Furthermore, the groove  21   b  with a spiral shape may also be formed in the inner ring (not shown). 
     While this present disclosure has been described in connection with what is presently considered to be practical exemplary forms. It is to be understood that the present disclosure is not limited to the disclosed forms, but, on the contrary, it is intended to cover various modification and equivalent arrangements included within the spirit and scope of the present disclosure.