Patent Publication Number: US-2023145204-A1

Title: Piston with oil return passage and engine

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Chinese Patent Application No. CN 202122733618.7, filed on Nov. 9, 2021, the contents of which is hereby incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     The utility model relates to the field of engines, in particular to a piston and an engine with an oil return channel. 
     BACKGROUND 
     As one of the core components of the engine, the piston of the engine is facing the challenge of higher durability and reliability. The durability of the piston is one of the most important factors affecting the reliability of the engine. Improving the initial and low engine fuel consumption under the durability life can well ensure that it meets the requirements of emission regulations in the whole life cycle. The design of oil return hole, as an important link to reduce oil consumption and durability, needs to be reasonably designed to improve the ability of oil return. 
     As shown in  FIG.  1    and  FIG.  2   , the existing design of oil return hole, but its effective oil return section is too small, resulting in: the oil return hole set at the upper end of the skirt is unfavorable to reducing the oil consumption at low speed and low load, and more oil will accumulate at the upper end of the skirt and even be sucked up; The oil return section is small, and the large amount of oil backflow encountered at high speed and high load is unfavorable. 
     As an improvement, an improved oil return hole is introduced in the patent Publication No. CN202832824U, which sets the oil return hole on the third annular bank and communicates with the surface window to facilitate oil return; In the patent Publication No. CN208935361U, the upper surface of the skirt of the piston body  1  is integrally formed with an oil storage tank  7 . In the actual cast or forged piston, the oil storage tank is machined, and the lower end of the second oil return window  8  is integrally formed with a stub shaft platform  9 . The short axis platform in the structure is obviously more protruding than the face window, so it is difficult to cast directly. 
     SUMMARY 
     In view of this, the disclosed embodiments provide a piston with an oil return passage and an engine to solve the problems in the prior art. 
     In order to solve the above technical problem, the present invention provides a piston having an oil return channel, the piston including: 
     Piston head, the head is provided with a ring groove; 
     Piston skirt, the skirt is connected to the head, the surface of the skirt is provided with a concave face window, and the connection between the face window and the ring groove forms a residual ring bank; 
     Oil return hole, the oil return hole is formed by milling on the residual ring bank, the oil return hole connects the ring groove close to the skirt with the face window, and the depth of the oil return hole is greater than the depth of the ring groove. 
     Furthermore, the size of the opening of the oil return hole is larger than the size of the bottom of the oil return hole. 
     Preferably, the axis of the oil return hole extends along the radial direction of the piston. 
     Preferably, a plurality of oil return holes are arranged, and a plurality of oil return holes are symmetrically distributed on the remaining ring bank. 
     Preferably, the difference between the depth of the oil return hole and the depth of the ring groove is 0.5-1.0 mm. 
     Preferably, the diameter range of the bottom of the oil return hole is Ø 8 mm- Ø 15 mm. 
     Preferably, the ring groove comprises at least one gas ring groove and at least one oil ring groove, the gas ring groove is located above the oil ring groove, and ring banks are arranged between the gas ring groove and the top of the head, between the gas ring groove and the oil ring groove, and between the oil ring groove and the skirt. 
     Preferably, the gas ring groove is a wedge-shaped ring groove or a rectangular ring groove and is internally provided with an air ring, the oil ring groove is a rectangular ring groove and is internally provided with an oil ring and an oil ring support spring. 
     Preferably, the annular groove includes one gas ring groove and at least one oil ring groove at least, and the gas ring groove is located oil ring groove top, all is equipped with the land between gas ring groove and the top of the head portion, between gas ring groove and the oil ring groove, between oil ring groove and the skirt portion. 
     Preferably, the gas ring groove is a wedge-shaped groove or a rectangular groove and is internally provided with a gas ring, and the oil ring groove is a rectangular groove and is internally. 
     In a second aspect, an engine provided by the embodiment of the present invention further includes the above-mentioned piston having the oil return channel. 
     The piston with the oil return channel and the engine have the advantages that: 
     The beneficial effects of a piston and an engine with an oil return channel of the utility model are: 
     1. The application adopts the milling method at the position of the remaining annular bank, and processes the oil return hole with circular open section with one feed. The opening size of the oil return hole is larger than the size of the bottom of the oil return hole, which greatly increases the area of the oil flow section and at least doubles the area of the oil flow section; The processing method of one-time feed milling has a simple processing path, which greatly reduces the production cost and improves the processing speed; 
     2. The opening size of the oil return hole of the application is larger than the size of the bottom of the oil return hole, and is connected with the face window, so that the oil is not easy to accumulate in the oil return hole, and the oil accumulated in the oil return hole is not easy to be sucked back to the combustion chamber when the engine runs at idle speed or low speed and low load, so as to reduce oil consumption and improve exhaust emission; 
     3. The depth of the oil return hole described in the application is greater than the diameter depth of the third ring groove, which reduces the risk of burr and avoids the risk that steel chips are not easy to come out during processing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a structural diagram of an oil return hole in the prior art; 
         FIG.  2    is a side sectional structural diagram of  FIG.  1   ; 
         FIG.  3    is the structural diagram of the piston with oil return channel of the utility model; 
         FIG.  4    is a sectional view of the head of the piston with an oil return channel of the utility model; and 
         FIG.  5    is a schematic cross-sectional view of the oil return hole of the piston with an oil return. 
     
    
    
     DESCRIPTION OF SYMBOLS 
       10  head;  11  first ring groove;  12  second ring groove;  13  third ring groove;  14 . The first ring bank;  15  second ring bank;  16  Third Ring bank;  17 . Residual ring bank;  18  gas ring;  19  oil ring;  110  oil ring support spring;  111  oil return hole; 
       20  skirt;  21  face windows. 
     DETAILED DESCRIPTION 
     The function of the oil return hole is to effectively return the oil in the cylinder to avoid the carbonization of lubricating oil such as oil and adhering to the piston ring groove or combustion chamber, affecting the engine performance and reducing the service life of the engine. Therefore, as an important means to reduce oil consumption and durability, the oil return hole needs to be reasonably designed to improve the oil return capacity. As shown in  FIGS.  3  to  5   , this embodiment provides a piston with an oil return channel, including a head  10  and a skirt  20  connected with it. The head  10  is provided with a ring groove, the surface of the skirt  20  is provided with a concave face window  21 , and the connection between the face window  21  and the ring groove forms a residual ring bank  17 ; At least one oil return hole  111  is arranged on the remaining annular bank  17 . 
     Specifically, the head  10  and the skirt  20  are cylindrical and integrally formed. 
     The piston with oil return channel is a steel piston. 
     More specifically, as shown in  FIGS.  4  and  5   , the ring groove includes a first ring groove  11 , a second ring groove  12  and a third ring groove  13 . The first ring groove  11  is close to the top of the head  10 , the third ring groove  13  is close to the skirt  20 , the second ring groove  12  is located between the first ring groove  11  and the third ring groove  13 , and a first ring bank  14  is formed between the top of the head  10  and the first ring groove  11 , A second annular bank  15  is formed between the first annular groove  11  and the second annular groove  12 , a third annular bank  16  is formed between the third annular groove  13  and the skirt  20 , and the third annular bank  16  is communicated with the remaining annular bank  17 . 
     The first ring groove  11  is a wedge-shaped or rectangular ring groove, the second ring groove  12  and the third ring groove  13  are rectangular ring grooves, the first ring groove  11  and the second ring groove  12  are provided with an air ring  18 , and the third ring groove  13  is provided with an oil ring  19  and an oil ring support spring  110 . 
     The diameters of the second annulus  15  and the third annulus  16  are greater than those of the first annulus  14 . 
     Because the piston is a steel piston, the first ring groove  11 , the second ring groove  12  and the third ring groove  13  can withstand higher strength collision and friction, the piston can withstand higher explosion pressure and the service life of the piston is longer. 
     Specifically, as shown in  FIG.  3   , the oil return hole  111  is formed by milling on the remaining annular bank  17 , and the opening size of the oil return hole  111  is larger than the size of the bottom of the oil return hole  111 . 
     The application adopts the milling method at the position of the residual ring bank to process the oil return hole with circular open section with one feed. With a simple processing path, the whole new form of oil hole manufacturing has a certain cost advantage. As shown in  FIG.  5   , the piston greatly increases the area of the oil flow section, at least doubling the area of the oil flow section. 
     The difference between the depth of the oil return hole  111  and the diameter depth of the third ring groove  13  ranges from 0.5 to 1.0 mm. The diameter range of the bottom of the oil return hole  111  is Ø 8Ø 15. 
     The risk of burr is reduced during piston processing, and the risk that steel chips are not easy to come out during processing is avoided. 
     The oil return holes  111  are provided with a plurality of oil return holes, which are symmetrically distributed on the surface window  21 , and form a plurality of remaining annular banks  17 . 
     In the specific embodiment of the application, the skirt  20  is provided with two relatively arranged face windows, and two remaining annular banks  17  are formed, and two oil return holes  111  are evenly distributed on each remaining annular bank  17 . 
     During the specific implementation, the oil can flow to the face window through the oil return hole to form an oil return channel, and then flow to the oil pan. The oil is not easy to accumulate in the oil return hole. When the engine is idling or running at low speed and small load, it is not easy to suck the oil accumulated in the oil return hole back to the combustion chamber, so as to reduce the oil consumption and improve the exhaust emission. 
     In specific implementation, a plurality of evenly distributed oil storage holes can also be arranged at the circumferential position of the third ring groove  13 . 
     In the second aspect, the embodiment of the present disclosure provides an engine, which also includes the piston with oil return channel. 
     During the implementation of the application, when the piston moves back and forth, the piston plays the role of oil scraping and oil distribution. For example, the application defines the direction close to the head  10  as above and the direction close to the skirt  20  as below. When the piston moves from top to bottom, the second ring bank scrapes the oil to the oil return hole and then flows to the face window to form an oil return channel; When the piston moves from bottom to bottom, the oil is distributed around the bank.