Patent Document

BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an engine oil pump, especially an engine oil pump that has simplified transmission mechanism for adjusting an output volume flow rate of engine oil. 
     2. Description of the Prior Art(s) 
     An engine oil pump is used for pressurizing and circulating engine oil. The engine oil pump provides the engine oil to a cylinder of an internal combustion engine for the purpose of lubrication, so as to allow pistons to slide smoothly. 
     With reference to  FIG. 7 , a conventional engine oil pump comprises a main seat  61 , a regulating valve  62 , an inner rotor  63 , an outer rotor  64 , and an eccentric wheel  65 . The main seat  61  has a first oil chamber  611 , a second oil chamber  612 , a pressurizing chamber  613 , an oil return channel  614 , and an oil regulating chamber  615 . The pressurizing chamber  613  is formed between the first oil chamber  611  and the second oil chamber  612 . The oil regulating chamber  615  communicates between the second oil chamber  612  and the oil return channel  614 . The regulating valve  62  is mounted in the oil regulating chamber  615 . The inner rotor  63  and the outer rotor  64  engage with each other and are mounted in the pressurizing chamber  613 . The eccentric wheel  65  surrounds the outer rotor  64  and is connected to the regulating valve  62  via a transmission assembly  66 . 
     When output oil pressure of the conventional oil engine pump is raised, the engine oil with raised output oil pressure pushes the regulating valve  62  to slide. Then the regulating valve  62  drives the eccentric wheel  65  to rotate by an angle via the transmission assembly  66 . Thus, quantity of the engine oil that is pressurized by the inner rotor  63  and the outer rotor  64  and is delivered to the second oil chamber  612  is reduced. Moreover, some of the engine oil in the second oil chamber  612  of the main seat  61  flows into the oil regulating chamber  615 , so the output oil pressure can be lowered. The engine oil in the oil regulating chamber  615  may further flow back to the first oil chamber  611  via the oil return channel  614  to lower down the output oil pressure automatically. Therefore, the conventional engine oil pump that has the transmission assembly  66 , the eccentric wheel  65 , and the gear type inner and outer rotors  63 ,  64  mounted in the main seat  61 , and the regulating valve  62  mounted in the oil regulating chamber  615  of the main seat  61  can well control flowing of the engine oil. 
     In the conventional engine oil pump, the transmission assembly  66  includes multiple gears engaging with each other, so as to drive the eccentric wheel  65  to rotate and to regulate and to circulate the engine oil. However, the conventional engine oil pump with the multiple gears needs too many components for driving related mechanisms. Therefore, the conventional engine oil pump has high manufacturing cost and high assembling complexity. Furthermore, since the gears transmit movements indirectly, the transmission assembly  66  of the conventional engine oil pump is inefficient. 
     To overcome the shortcomings, the present invention provides a variable flow engine oil pump to mitigate or obviate the aforementioned problems. 
     SUMMARY OF THE INVENTION 
     The main objective of the present invention is to provide a variable flow engine oil pump. The variable flow engine oil pump has a first seat, a second seat attached to the first seat, and a regulating valve assembly and a pressurizing assembly mounted in the second seat. An eccentric wheel of the pressurizing assembly meshes with a plug of the regulating valve assembly. 
     With the plug driving the eccentric wheel to rotate by an angle, a volume flow rate of engine oil output by the engine oil pump can be adjusted. Elements used for adjusting the output volume flow rate of the engine oil are reduced, and manufacturing cost and assembling complexity of the engine oil pump are lowered accordingly. Moreover, since the regulating valve assembly drives the pressurizing assembly directly, the regulating valve assembly can drive the pressurizing assembly efficiently. 
     Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a variable flow engine oil pump in accordance with the present invention; 
         FIG. 2  is an exploded perspective view of the variable flow engine oil pump in  FIG. 1 ; 
         FIG. 3  is another exploded perspective view of the variable flow engine oil pump in  FIG. 1 ; 
         FIG. 4  is a cross-sectional top view of the variable flow engine oil pump in  FIG. 1 ; 
         FIG. 5  is a top view of the variable flow engine oil pump in  FIG. 1 ; 
         FIG. 6  is an operational top view of the variable flow engine oil pump in  FIG. 1 ; and 
         FIG. 7  is an exploded perspective view of a conventional engine oil pump in accordance with the prior art. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to  FIGS. 1 and 2 , a variable flow engine oil pump in accordance with the present invention comprises a first seat  10 , a second seat  20 , a regulating valve assembly  24 , and a pressurizing assembly  30 . 
     With reference to  FIGS. 2 and 3 , the first seat  10  has an inner surface, two opposite ends, an outer sidewall, a first axial hole  11 , a first recess  101 , a second recess  102 , an oil return channel  12 , and multiple first fastening holes  13 . The first axial hole  11  is formed through the first seat  10 . The first recess  101  and the second recess  102  are formed in the inner surface of the first seat  10  and are respectively disposed adjacent to the two ends of the first seat  10 . The oil return channel  12  is formed in the inner surface of the first seat  10  and communicates with the first recess  101 . The first fastening holes  13  are separately formed through the first seat  10  and are arranged along the outer sidewall of the first seat  10 . 
     With reference to  FIGS. 2 to 4 , the second seat  20  is attached to the first seat  10  and has an inner surface, two opposite ends, an outer sidewall, a mounting recess  200 , a second axial hole  21 , a third recess  201 , a fourth recess  202 , an oil inlet  203 , an oil outlet  204 , an oil regulating chamber  22 , a positioning groove  221 , a guiding channel  205 , an oil return hole  23 , and multiple second fastening holes  25 . 
     The inner surface of the second seat  20  faces and is attached to the inner surface of the first seat  10 . The mounting recess  200  is formed in the inner surface of the second seat  20 . The second axial hole  21  is formed through the second seat  20 , corresponds in position to the mounting recess  200 , and aligns with the first axial hole  11  of the first seat  10 . Specifically, the second axial hole  21  is formed through an inner bottom defined in the mounting recess  200 . 
     The third recess  201  is formed in the inner surface of the second seat  20 , is disposed adjacent to one of the ends of the second seat  20 , and communicates with the mounting recess  200 . The third recess  201  corresponds in position to and communicates with the first recess  101  of the first seat  10 . The third recess  201  and the first recess  101  form an oil inlet chamber  40 . Since the oil return channel  12  communicates with the first recess  101 , the oil return channel  12  communicates with the oil inlet chamber  40  as well. The fourth recess  202  is formed in the inner surface of the second seat  20 , is disposed adjacent to the other end of the second seat  20 , and communicates with the mounting recess  200 . The fourth recess  202  corresponds in position to and communicates with the second recess  102  of the first seat  10 . The fourth recess  202  and the second recess  102  form an oil outlet chamber  50 . 
     The oil inlet  203  is formed through the second seat  20 . Specifically, the oil inlet  203  is formed through an inner bottom defined in the third recess  201  of the second seat  20 . The oil outlet  204  is formed through the second seat  20 . Specifically, the oil outlet  204  is formed through an inner bottom defined in the fourth recess  202  of the second seat  20 . 
     The oil regulating chamber  22  is formed in the second seat  20 , is elongated, and communicates with the mounting recess  200 . The oil regulating chamber  22  has an inner end and an outer end. The outer end of the oil regulating chamber  22  communicates with an exterior of the second seat  20 . The positioning groove  221  is formed in an interior surface defined around the oil regulating chamber  22  and is disposed adjacent to the outer end of the oil regulating chamber  22 . The guiding channel  205  is formed in the second seat  20 , communicates between the inner end of the oil regulating chamber  22  and the fourth recess  202 , and between the oil regulating chamber  22  and the oil outlet chamber  50 . 
     With reference to  FIG. 6 , the oil return hole  23  is formed in the inner surface of the second seat  20 , communicates with the oil regulating chamber  22 , and corresponds in position to and communicates with the oil return channel  12  of the first seat  10 . 
     The second fastening holes  25  are separately formed through the second seat  20 , are arranged along the outer sidewall of the second seat  20 , and respectively align with the first fastening holes  13  of the first seat  10 . Multiple fasteners are mounted through the first fastening holes  13  and the second fastening holes  25 , such that the first seat  10  and the second seat  20  are securely held together. The fasteners may be screws or bolts incorporated with nuts. 
     With reference to  FIGS. 2 and 4 , the regulating valve assembly  24  is mounted in the oil regulating chamber  22  of the second seat  20 , and includes a plug  241 , an end cap  243 , a resilient element  242 , and a retaining ring  244 . 
     The plug  241  is cylindrical, is slidably mounted in the oil regulating chamber  22  of the second seat  20 , and selectively seals the oil return hole  23 . The plug  241  has an outer surface, an open end, a closed end, a receiving recess, and a driving toothed portion  2411 . The closed end of the plug  241  corresponds in position to the inner end of the oil regulating chamber  22 , and faces and selectively seals the guiding channel  205 . The receiving recess of the plug  241  is formed in the open end of the plug  241 . The driving toothed portion  2411  is formed on the outer surface of the plug  241 , is disposed adjacent to the closed end of the plug  241 , and is exposed to the mounting recess  200  of the second seat  20 . 
     The end cap  243  is mounted in the oil regulating chamber  22  of the second seat  20  and is disposed adjacent to the outer end of the oil regulating chamber  22 . The end cap  243  has an outer end surface, an inner end surface, and a mounting protrusion. The mounting protrusion of the end cap  243  is formed on and protrudes from the inner end surface of the end cap  243 . 
     The resilient element  242  protrudes in the receiving recess of the plug  241  and has two opposite ends. The ends of the resilient element  242  respectively abut the plug  241  and the second seat  20 . One of the ends of the resilient element  242  is mounted in the receiving recess of the plug  241  and abuts the plug  241 . The other end of the resilient element  242  is mounted around the mounting protrusion of the end cap  243  and abuts the inner end surface of the end cap  243 . In the preferred embodiment, the resilient element  242  is a compression spring. 
     The retaining ring  244  engages in the positioning groove  221  that is disposed in the oil regulating chamber  22  and abuts the outer end surface of the end cap  243 . Thus, the end cap  243 , the resilient element  242 , and the plug  241  are constrained in the oil regulating chamber  22  of the second seat  20 . In the preferred embodiment, the retaining ring  244  is a C-clip. 
     With reference to  FIGS. 2 to 4 , the pressurizing assembly  30  is mounted in the mounting recess  200  of the second seat  20  and includes an inner rotor  31 , an outer rotor  32 , and an eccentric wheel  33 . 
     The inner rotor  31  is annular and has an outer sidewall, an end surface, a central hole  311 , multiple teeth  312 , and an annular protrusion  313 . The end surface of the inner rotor  31  faces the second seat  20 . The central hole  311  is formed through the inner rotor  31  and aligns with the first axial hole  11  of the first seat  10  and the second axial hole  21  of the second seat  20 . Preferably, the central hole  311  is non-circular in cross-section. The teeth  312  of the inner rotor  31  are separately formed on and arranged around the outer sidewall of the inner rotor  31 . The annular protrusion  313  is formed on the end surface of the inner rotor  31  and around the central hole  311 , and protrudes in the second axial hole  21  of the second seat  20 . 
     The outer rotor  32  is annular, is mounted around the inner rotor  31 , and has an inner sidewall and multiple teeth  321 . The teeth  321  of the outer rotor  32  are separately formed on and arranged around the inner sidewall of the outer rotor  32 . An inner diameter of the outer rotor  32  is larger than an outer diameter of the inner rotor  31 . Some of the teeth  321  of the outer rotor  32  mesh with some of the teeth  312  of the inner rotor  31 . Accordingly, a gap is formed between the other teeth  321  of the outer rotor  32  and the other teeth  312  of the inner rotor  31  that do not mesh with each other. The gap selectively corresponds in position to and communicates with the oil inlet chamber  40  and the oil outlet chamber  50 . 
     The eccentric wheel  33  is annular, is rotatably mounted in the mounting recess  200  of the second seat  20 , is securely mounted around the outer rotor  32 , and has an outer sidewall, a driven toothed portion  331 , and an eccentric hole  332 . The driven toothed portion  331  is formed on the outer sidewall of the eccentric wheel  33  and meshes with the driving toothed portion  2411  of the plug  241 . The eccentric hole  332  is formed through the eccentric wheel  33 . An inner diameter of the eccentric hole  332  of the eccentric wheel  33  corresponds in size to an outer diameter of the outer rotor  32 . Thus, the outer rotor  32  is fitted in the eccentric wheel  33  with an outer sidewall of the outer rotor  32  abutting an inner sidewall of the eccentric wheel  33 . 
     With further reference to  FIG. 5 , during operation, a driving shaft is mounted through the central hole  311  of the inner rotor  31 , drives the inner rotor  31  to rotate, and drives the outer rotor  32  to rotate via the inner rotor  31 . The inner rotor  31  and the outer rotor  32  are eccentric and mesh with each other by the teeth  312 ,  321 . Engine oil that flows through the oil inlet  203  and into the oil inlet chamber  40  is drawn into the gap between the inner rotor  31  and the outer rotor  32 . When the inner rotor  31  and the outer rotor  32  are driven to rotate, a capacity of the gap increases and decreases alternately. As the capacity of the gap decreases, the engine oil in the gap is compressed and is delivered to the oil outlet chamber  50 . Then the compressed engine oil flows out through the oil outlet  204  and is provided to a cylinder of an internal combustion engine. 
     With further reference to  FIG. 6 , when needful quantity of the engine oil of the combustion is less than an output of the engine oil of the variable flow engine oil pump, oil pressure of the engine oil that is output from the engine oil pump would be raised. Then, the engine oil in the oil outlet chamber  50  flows into the guiding channel  205  to push the closed end of the plug  241 , and the resilient element  242  is compressed accordingly. Thus, the plug  241  slides away from the guiding channel  205 , and the engine oil further flows into the oil regulating chamber  22 . Since the driving toothed portion  2411  of the plug  241  meshes with the driven toothed portion  331  of the eccentric wheel  33 , as the plug  241  slides, the plug  241  drives the eccentric wheel  33  as well as the outer rotor  32  to rotate by an angle. Thus, a relative position of the outer rotor  32  and the inner rotor  31  changes, and a quantity of the engine oil that is delivered by the outer rotor  32  and the inner rotor  31  is reduced. Accordingly, the oil pressure of the engine oil that is output from the engine oil pump can be reduced. Moreover, the oil pressure of the engine oil that is output from the engine oil pump can also be reduced with the engine oil flowing from the oil outlet chamber  50  to the oil regulating chamber  22 . 
     As shown in  FIG. 6 , as the oil pressure of the engine oil in the oil outlet chamber  50  is raised continuously, the plug  214  in the oil regulating chamber  22  is pushed farther away from the guiding channel  205 , and the oil return hole  23  is opened. Thus, the engine oil that flows in the oil regulating chamber  22  further flows through the oil return hole  23 , the oil return channel  12  and flows back to the oil inlet chamber  40 . The oil pressure of the engine oil that is output from the engine oil pump is further reduced accordingly. 
     Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and features of the invention, the disclosure is illustrative only. Changes may be made in the details, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Technology Category: 2