JP2007332941A - Structure of engine oil pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrict the biased wear-off of a relief valve provided in a relief chamber 31 located in an oil pump body 12 to assure the relief valve of its reliable long-time operation. <P>SOLUTION: Two relief holes 35, 36 are opened at the ambient wall of a relief chamber 31 on the side of a suction chamber 19, and two penetration holes 45, 46 are opened at the ambient wall part located opposite to the suction chamber 19. The relief hole 35 is communicated with the penetration hole 45 circumferentially closer to it by connections 48 formed by notching the ambient wall part of the relief chamber 31 located between the relief hole 35 and the penetration hole 45 and close to the relief chamber 31. A recess 51 is formed at the installation surface 12a of the pump body 12. This recess 51 is shaped so that the two penetration holes 45, 46 can communicate with each other when the opening of the recess 51 and an opening formed by the two penetration holes 45, 46 on the side of the installation surface 12a are closed with the engine main body. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an oil pump structure for an engine, and particularly relates to a technical field of a device having a relief hole and a relief valve that opens and closes the relief hole.

Conventionally, for example, as shown in Patent Document 1, an oil pump is attached to one end of the engine body in the cylinder row direction, and the pump shaft of the oil pump is connected to the crankshaft of the engine body via a timing chain. It is known to be driven by. In the pump body of this oil pump, a suction chamber and a discharge chamber are usually formed across a rotor chamber in which a pump rotor that is rotated by driving a pump shaft is disposed. A discharge passage is formed for guiding oil to the nozzle. Further, as disclosed in Patent Document 2, the oil pump is provided with a relief hole and a relief valve that opens and closes the relief hole. When the engine speed increases, the relief valve is provided. Thus, the relief hole is opened, and part of the oil discharged from the discharge chamber is discharged from the relief hole, thereby stabilizing the pressure or amount of oil supplied to the engine body.
Japanese Patent Laid-Open No. 2002-115600 (6th page, FIG. 4, FIG. 6) JP-A-8-158842

  By the way, the oil discharged from the relief hole is normally returned to the suction chamber. This is because returning to the oil pan causes the oil pump to perform the extra work of pumping oil from the oil pan again, thus reducing pump efficiency. Therefore, the relief hole is provided in the peripheral wall portion of the relief chamber in which the relief valve is provided so as to communicate the suction chamber and the relief chamber.

  Here, as in Patent Document 1, the pump body of the oil pump is arranged in the cylinder row direction in the engine body through the mounting surface with the end surface on one side in the axial direction of the pump shaft in the pump body as the mounting surface. In the case of mounting on one end, the suction chamber and the discharge chamber are provided on the side of the pump body opposite to the mounting surface in order to improve the arrangement efficiency in the pump body, and the discharge passage and the relief chamber are , Provided on the mounting surface side of the pump body. In this case, the relief chamber is disposed so as to open to the discharge passage and pass through the attachment surface side from the opening to the suction chamber. For this reason, the relief hole is formed in the suction chamber side (that is, the side opposite to the mounting surface) in the peripheral wall portion of the relief chamber, and is not formed in the mounting surface side in the peripheral wall portion of the relief chamber.

  However, if the relief holes are formed only in the portion of the peripheral wall portion of the relief chamber opposite to the mounting surface, the following problems arise. That is, the relief valve is normally configured to open and close the relief hole by moving in the longitudinal direction of the relief chamber with the peripheral wall surface of the relief chamber as a guide surface. Since the pressure becomes negative pressure, the relief valve is shifted to the relief hole side of the relief chamber by the negative pressure. As a result, the relief valve side portion of the relief valve rubs against the surrounding wall surface to cause uneven wear. When this uneven wear increases, there is a problem that the relief valve does not operate.

  The present invention has been made in view of such points, and an object of the present invention is to provide an oil pump having a relief hole and a relief valve for opening and closing the relief hole as described above. By elaborating the invention, it is intended to suppress the occurrence of uneven wear of the relief valve and to ensure that the relief valve operates over a long period of time.

  In order to achieve the above object, according to the present invention, a through hole is formed in a portion of the peripheral wall portion of the relief chamber opposite to the suction chamber (a portion opposite to the relief hole), and also in the through hole. A negative pressure was generated in the same manner as the relief hole.

  Specifically, in the invention of claim 1, a pump body provided with a pump shaft driven by a crankshaft of an engine body has an end surface on one side in the axial direction of the pump shaft as an attachment surface. A pump rotor that is attached to one end of the engine body on one side in the cylinder row direction via the attachment surface and that rotates by driving the pump shaft is disposed on a portion of the pump body opposite to the attachment surface. A suction chamber and a discharge chamber are formed across the rotor chamber, and extends from the discharge chamber toward the mounting surface at the portion on the mounting surface side of the pump body and opens to the mounting surface. A discharge passage, and a relief chamber that is open to the discharge passage and extends from the opening to the suction surface with respect to the attachment surface side. A relief hole that communicates the suction chamber and the relief chamber is formed in the surrounding wall, and the relief hole is opened and closed by moving in the longitudinal direction of the relief chamber with the surrounding wall surface of the relief chamber as a guide surface. A relief valve is provided, and the relief valve opens the relief hole so that a part of the oil discharged from the discharge chamber to the discharge passage is returned to the suction chamber through the relief chamber and the relief hole. The engine oil pump structure is the target.

  And the said relief hole is formed in the part by the side of the said suction chamber in the surrounding wall part of the said relief chamber along with the circumferential direction through a relief valve guide surface part between two, and the surrounding wall part of the said relief chamber In the portion on the opposite side to the suction chamber, there are two through-holes that are arranged in the circumferential direction with a relief valve guide surface portion therebetween and penetrate the peripheral wall portion so as to open to the mounting surface and the relief chamber. The one relief hole and the through hole on the side close to the relief hole in the circumferential direction are formed by notching the relief chamber side of the peripheral wall portion of the relief chamber between the relief hole and the through hole. The other relief hole and the through hole on the side close to the relief hole in the circumferential direction are connected to each other by a connecting portion on the peripheral wall portion of the relief chamber between the relief hole and the through hole. The recesses are formed in the mounting surface, and the opening of the recess and the opening on the mounting surface side of the two through holes are connected to the engine body through the mounting surface by the pump body. When mounted, the engine is closed by the engine body, and the recess closes the opening of the recess and the opening on the mounting surface side in the two through holes by the engine body. In this state, the two through holes are formed to communicate with each other.

  With the above configuration, two relief holes are formed in the suction chamber side portion of the peripheral wall portion of the relief chamber (that is, the portion on the side opposite to the mounting surface). Two through holes are formed in the portion (that is, the portion on the mounting surface side), and one relief hole and the through hole on the side closer to the relief hole in the circumferential direction are relief between the relief hole and the through hole. They are connected to each other by a connection portion formed by cutting out the relief chamber side of the peripheral wall portion of the chamber. Thereby, the inside of this through-hole is made into a negative pressure via a connection part.

  On the other hand, the through hole on the side close to the other relief hole in the circumferential direction is not connected to the other relief hole by the connecting portion as described above. However, since the two through holes communicate with each other by the recess formed on the mounting surface, the inside of the through hole also has a negative pressure. Thus, even if the through hole on the side closer to the circumferential direction than the other relief hole is not connected to the other relief hole, the inside of the through hole can be negatively formed with a simple structure in which a recess is formed on the mounting surface. Pressure.

  Therefore, holes (relief holes and through-holes) that become negative pressure when the oil pump is operated are formed in the peripheral wall of the relief chamber in a well-balanced manner in the entire circumferential direction. Does not act, and the occurrence of uneven wear of the relief valve is suppressed.

  According to a second aspect of the present invention, in the first aspect of the invention, the pump body is formed by a split mold having first and second molds that are opened and closed in the axial direction of the pump shaft. The pump body is formed by a first mold on the mounting surface side, and the relief hole is formed by a second mold on the pump body opposite to the mounting surface.

  In the invention of claim 3, in the invention of claim 2, the recess is formed by the first mold.

  From these inventions, the entire pump body including the through hole, the relief hole, and the recess can be simultaneously formed in a split mold, and the cost can be reduced when the pump body is manufactured.

  In the invention of claim 4, the pump body provided with the pump shaft driven by the crankshaft of the engine body has an end surface on one side in the axial direction of the pump shaft in the pump body as the mounting surface, and the pump body is interposed through the mounting surface. A rotor chamber that is attached to an end of the engine body on one side in the cylinder row direction and that has a pump rotor that is rotated by driving of the pump shaft is disposed on the opposite side of the mounting surface of the pump body. A suction chamber and a discharge chamber, and a discharge passage that extends from the discharge chamber toward the mounting surface and opens to the mounting surface in a portion of the pump body on the mounting surface side, A relief chamber that opens to the discharge passage and extends from the opening to pass through the mounting surface side with respect to the suction chamber, and is formed on a peripheral wall portion of the relief chamber, A relief hole is formed to communicate the suction chamber and the relief chamber, and a relief valve that opens and closes the relief hole by moving in the longitudinal direction of the relief chamber with the peripheral wall surface of the relief chamber as a guide surface is formed in the relief chamber. An engine is provided, wherein the relief valve opens the relief hole so that a part of the oil discharged from the discharge chamber to the discharge passage is returned to the suction chamber through the relief chamber and the relief hole. For oil pump structure.

  And the said relief hole is formed in the part by the side of the said suction chamber in the surrounding wall part of the said relief chamber along with the circumferential direction through a relief valve guide surface part between two, and the surrounding wall part of the said relief chamber In the portion on the opposite side to the suction chamber, there are two through-holes that are arranged in the circumferential direction with a relief valve guide surface portion therebetween and penetrate the peripheral wall portion so as to open to the mounting surface and the relief chamber. The one relief hole and the through hole on the side close to the relief hole in the circumferential direction are formed by notching the relief chamber side of the peripheral wall portion of the relief chamber between the relief hole and the through hole. The other relief hole and the through hole on the side close to the relief hole in the circumferential direction are connected to each other by the first connecting portion, and the peripheral wall of the relief chamber between the relief hole and the through hole Are connected to each other by a second connecting portion formed by cutting out the relief chamber side, and the opening on the mounting surface side in the two through holes is a state in which the pump body is attached to the engine body via the mounting surface It is assumed that the engine is closed by the engine body.

  As a result, the one relief hole and the through hole on the side close to the relief hole in the circumferential direction are connected via the first connecting portion, as in the invention of claim 1, and the other relief hole and Since the through hole on the side closer to the relief hole in the circumferential direction is connected via the second connection portion, the two through holes are each set to a negative pressure via the first and second connection portions. Therefore, similarly to the first aspect, the occurrence of uneven wear of the relief valve is suppressed.

  According to a fifth aspect of the present invention, in the fourth aspect of the invention, the pump body is formed by a split mold having first and second molds that are opened and closed in the axial direction of the pump shaft. The pump body is formed by a first mold on the mounting surface side, and the relief hole is formed by a second mold on the pump body opposite to the mounting surface.

  Thus, like the invention of claim 2, the entire pump body including the relief hole can be simultaneously formed in a split mold, and the cost can be reduced when the pump body is manufactured.

  According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the two relief holes and the two through holes are at substantially the same position in the longitudinal direction of the relief chamber.

  In this way, the oil can be reliably returned to the suction chamber by the relief valve, and the bending moment of the relief valve can be prevented from being generated by the negative pressure, thereby ensuring the uneven wear of the relief valve. Can be suppressed.

  As described above, according to the oil pump structure of the engine of the present invention, the holes (relief holes and through holes) that become negative pressure when the oil pump is operated are balanced across the entire circumferential direction in the peripheral wall portion of the relief chamber. By making it well formed, it is possible to suppress the occurrence of uneven wear of the relief valve, so that the relief valve operates reliably over a long period of time.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
1 and 2 show a cylinder block 3 of an engine body in an engine to which an oil pump 11 to which an oil pump structure according to Embodiment 1 of the present invention is applied is attached. In this embodiment, this engine is an in-line four-cylinder gasoline engine in which four cylinders are arranged in series in a direction in which a crankshaft (the axis of the crankshaft is shown as X in FIG. 1) extends.

  In this embodiment, the cylinder row direction, that is, the direction in which the crankshaft extends (the direction perpendicular to the plane of FIG. 1, the left-right direction in FIG. 2) is the engine front-rear direction, and the output end side of the crankshaft (in FIG. The back side of the page, the right side of FIG. 2, is called the rear side of the engine, while the opposite side (the front side of the page of FIG. 1, the left side of FIG. 2) is called the front side of the engine. The left-right direction perpendicular to the cylinder row direction is called the engine width direction.

  The front end wall 3a constituting the end of the cylinder block 3 on one side in the cylinder row direction (the front side of the engine) has protruding wall portions 54 that protrude from the upper end to the lower end at both ends in the engine width direction, 54 and one cover mounting boss 75 projecting in a circular shape at the center in the engine width direction at the top of the front end wall 3a. Each of the protruding wall portions 54 and the cover mounting boss portion 75 constitute a cover mounting portion for mounting and fixing a front cover (not shown), and each of the protruding wall portions 54 and the cover mounting boss portion 75 includes a front cover. Screw holes 76 into which the mounting bolts are screwed are formed (a plurality of screw holes 76, 76,... Are formed in each protruding wall portion 54, and one screw hole 76 is formed in the cover mounting boss portion 75, respectively. Formed). The mounting bolts attach and fix the peripheral edge of the front cover to the protruding wall portions 54 and the central portion to the cover mounting boss portion 75, respectively, between the front cover and the front end wall portion 3a. A flat space portion for accommodating a timing chain for driving an oil pump 11, a water pump, a valve operating system and the like, which will be described later, is formed.

  Of the projecting walls 54, 54, the projecting wall on the right side in FIG. 1 (because an intake manifold is provided on the right side wall portion when viewed from the front of the cylinder block 3, the right side in FIG. A circular opening that communicates with a pump chamber 55 in which a water pump (not shown) is disposed is formed in the upper portion of the portion 54. A portion of the pump chamber 55 on the rear side of the engine communicates with a thermostat chamber 72 that houses a thermostat (not shown). Then, when the impeller of the water pump housed in the pump chamber 55 rotates, the cooling water supplied from the radiator side is sucked into the pump chamber 55 from the thermostat chamber 72, and the cooling water is radiated in the radial direction of the pump chamber 55. It flows outward and is discharged from the discharge port, and then flows into a water jacket provided in the cylinder block 3.

  The cylinder block 3 is a deep skirt type in which both side wall portions on both sides in the engine width direction extend to a position below the axis X of the crankshaft, and a portion surrounded by both skirt portions is A crank chamber 58 for accommodating the crankshaft is provided. A plurality of main bearing portions 59 are formed in the crank chamber 58 so as to be arranged in the longitudinal direction of the engine. A bearing cap 60 is disposed on each of the main bearing portions 59, and the bearing caps 60 are in contact with each other. In a state of being connected by the beam 61, the bolt 62 is fastened and fixed to the main bearing portion 59.

  A pump mounting portion 3b to which an oil pump 11 for pumping oil for lubrication of the engine to each part of the engine is mounted on the inner side in the engine width direction below the intake side protruding wall portion 54 in the front end wall portion 3a. Yes. The pump mounting portion 3b has a front end wall portion 3a that is recessed by substantially the same length as the oil pump 11, and has a flat surface perpendicular to the crankshaft.

  The oil pump 11 includes a pump body 12 and a pump cover 13 attached to a surface of the pump body 12 on the front side of the engine (a surface opposite to a mounting surface 12a described later). The pump body 12 is provided with a pump shaft 15 extending in parallel with the crankshaft. The pump shaft 15 penetrates the pump cover 13, and an engine front side end portion of the pump shaft 15 projects from the pump cover 13 to the engine front side. A sprocket (not shown) is fixed to the front end portion of the pump shaft 15 on the engine, and the pump shaft is connected via a timing chain wound between the sprocket and the sprocket attached to the crankshaft. 15 is driven by a crankshaft.

  The pump body 12 has an end surface (engine rear side end surface) on one side in the axis P direction of the pump shaft 15 of the pump body 12 as a mounting surface 12a, and the cylinder body 3 of the engine body via the mounting surface 12a. It is attached to one end of the cylinder row direction (the pump attachment portion 3b of the front end wall portion 3a). The mounting surface 12a is a flat surface perpendicular to the crankshaft (pump shaft 15), like the pump mounting portion 3b, and has four bolt insertion holes 22, 22,... Provided in the pump body 12 (FIG. 3). 4 and 6), a bolt (not shown) inserted into the pump mounting portion 3b is in close contact with the bolt. The pump cover 13 is also provided with four bolt insertion holes 23, 23,... (See FIG. 1) corresponding to the bolt insertion holes 22 of the pump body 12, and the pump cover 13 is also simultaneously provided by the bolts. It will be attached to the pump body 12.

  Next, the configuration of the pump body 12 will be described in detail with reference to FIGS.

  The pump body 12 has a shape that can be cast-molded by a split mold having first and second molds that are opened and closed in the direction of the axis P of the pump shaft 15, and is cast by the split mold. That is, the first type and the second type of the split type are matched with each other by a parting line (PL) indicated by a one-dot chain line in FIG. 6, and in this state, the first type is positioned on the mounting surface 12a side. The second mold is located on the opposite side of the mounting surface 12a. After the molding, the first mold moves to the engine rear side, and the second mold moves to the engine front side, so that the split mold is opened. The relief chamber 31 described later is formed by a slide mold that moves in a direction perpendicular to the axis P of the pump shaft 15. There are other parts that are partially molded by the slide mold.

  A portion of the pump body 12 opposite to the mounting surface 12a is separated by a rotor chamber 18 in which an inner rotor 16 and an outer rotor 17 (see FIG. 2) serving as a pump rotor rotating by driving the pump shaft 15 are disposed. Thus, a suction chamber 19 and a discharge chamber 20 are formed (see FIGS. 2, 3 and 5). That is, the suction chamber 19 is formed below the rotor chamber 18, and the discharge chamber 20 is formed above the rotor chamber 18. The suction chamber 19 communicates with a passage in the connection portion 25 through an opening 25a on the suction chamber side of the connection portion 25 connected to an oil strainer disposed in an oil pan (not shown).

  In the present embodiment, the oil pump 11 is an internal gear type pump, and external teeth are provided on the outer peripheral surface of the inner rotor 16 that is integrally fixed to the pump shaft 15, and the inner rotor is provided on the inner peripheral surface of the outer rotor 17. Internal teeth that mesh with the 16 external teeth are provided. The inner rotor 16 rotates eccentrically with respect to the pump shaft 15 and the outer rotor 17, and the oil in the oil pan is engaged with the outer teeth of the inner rotor 16 and the inner teeth of the outer rotor 17 during the rotation. Is sucked into the suction chamber 19 through the opening 25 a on the suction chamber side of the connecting portion 25, and the oil is discharged to the discharge chamber 20 through the rotor chamber 18. A bearing portion 27 (see FIGS. 3 and 5) that rotatably supports the end portion of the pump shaft 15 on the mounting surface 12a side is formed on the wall portion of the rotor chamber 18 on the mounting surface 12a side. Yes.

  In the portion of the pump body 12 on the mounting surface 12a side, a discharge passage 30 (FIG. 3) that extends in parallel with the axis P of the pump shaft 15 from the discharge chamber 20 toward the mounting surface 12a and opens to the mounting surface 12a. To FIG. 5), and a cross section that opens into the discharge passage 30 and extends from the opening in a direction (downward) perpendicular to the axis P of the pump shaft 15 and passes through the mounting surface 12 a side with respect to the suction chamber 19. A circular relief chamber 31 (see FIGS. 5 to 8) is formed.

  The opening on the attachment surface 12a side in the discharge passage 30 is connected to an oil supply passage 81 provided in the cylinder block 3 when the pump body 12 is attached to the pump attachment portion 3b via the attachment surface 12a. (See FIG. 2). The oil supply path 81 extends in the front-rear direction of the engine, and the end portion on the front side of the engine opens to the front end wall portion 3a of the cylinder block 3, and the opening on the mounting surface 12a side of the discharge passage 30 opens in this opening. Is connected. On the other hand, the end of the oil supply path 81 on the rear side of the engine is bent toward the intake side of the cylinder block 3 and is opened in the side wall portion on the intake side, and this opening is connected to an oil filter (not shown). As a result, the oil discharged from the discharge chamber 20 to the discharge passage 30 is guided to the oil filter through the oil supply passage 81 of the cylinder block 3, and the oil filtered by the oil filter is again supplied to the cylinder block 3. And is led to a main gallery (not shown).

  The lower end of the relief chamber 31 is open to the lower surface of the pump body 12 (see FIGS. 5, 7, and 8). The opening is closed by a closing member 32 as shown by a two-dot chain line in FIG. The relief chamber 31 includes an upper (discharge passage side) small-diameter portion 31a and a lower large-diameter portion 31b. The large-diameter portion 31b is substantially at the same height as the suction chamber 19, and the suction chamber It is located on the mounting surface 12 a side with respect to the chamber 19.

  A relief valve 33 that opens and closes relief holes 35 and 36 to be described later is provided in the large-diameter portion 31 b of the relief chamber 31. The relief valve 33 has a circular cross-section and a diameter slightly smaller than the cross-sectional diameter of the large-diameter portion 31b, and the longitudinal direction (vertical direction) of the relief chamber 31 using the peripheral wall surface of the large-diameter portion 31b as a guide surface. ) Can be moved. When the pressure of the oil discharged into the discharge passage 30 is not more than a predetermined value, the relief valve 33 is urged upward by a compression spring 34 provided between the relief valve 33 and the closing member 32, thereby releasing the relief valve 33. The upper end surface of the valve 33 is in contact with the stepped portion at the boundary between the small diameter portion 31a and the large diameter portion 31b.

  Two relief holes 35 communicating the suction chamber 19 and the relief chamber 31 are formed in a portion of the peripheral wall portion of the large-diameter portion 31b of the relief chamber 31 on the side of the suction chamber 19 (opposite to the mounting surface 12a). 36 (see FIGS. 3, 5 and 6) is formed. These two relief holes 35 and 36 are arranged in the circumferential direction of the relief chamber 31 between the two relief holes 35 and 36 via the relief valve guide surface portion 40 (see FIG. 6). At substantially the same position in the longitudinal direction. Further, the two relief holes 35 and 36 both extend parallel to the axis P of the pump shaft 15. Thus, the two relief holes 35 and 36 together with the rotor chamber 18, the suction chamber 19, the discharge chamber 20, and the discharge passage 30 have a shape that can be molded by the split second mold, and the second Molded by a mold.

  The relief valve 33 closes the relief holes 35 and 36 when the upper end surface of the relief valve 33 is in contact with the stepped portion. When the engine speed increases and the pressure of the oil discharged to the discharge passage 30 becomes higher than a predetermined value (the oil flow rate increases accordingly), the relief valve 33 is compressed by the pressure. It moves downward against the urging force of the spring 34 to open the relief holes 35 and 36. Thus, a part of the oil discharged from the discharge chamber 20 into the discharge passage 30 is returned to the suction chamber 19 through the relief chamber 31 and the relief holes 35 and 36. Thus, the pressure or amount of oil supplied to the oil supply passage 81 of the cylinder block 3 is stabilized.

  As described above, the relief holes 35 and 36 are formed in a portion of the peripheral wall portion of the large-diameter portion 31b of the relief chamber 31 on the side opposite to the mounting surface 12a, and when the oil pump 11 is operated, the relief holes 35 and 36 are formed. Since the suction chamber 19 and the relief holes 35 and 36 have a negative pressure, if only the relief holes 35 and 36 are opened in the peripheral wall portion of the relief chamber 31, the relief valve 33 is relieved by the negative pressure. The chamber 31 is shifted to the side opposite to the mounting surface 12a. As a result, the portion of the relief valve 33 opposite to the mounting surface 12a is rubbed against the peripheral wall surface of the large diameter portion 31b to cause uneven wear. When this uneven wear increases, the relief valve 33 cannot move in the vertical direction, Oil leakage may occur between the relief valve 33 and the peripheral wall surface of the large diameter portion 31b, resulting in malfunction of the relief valve 33.

  Therefore, in the present embodiment, two through holes 45 and 46 (FIGS. 4 to 6) are formed in a portion of the peripheral wall portion of the large-diameter portion 31b of the relief chamber 31 opposite to the suction chamber (that is, the portion on the mounting surface 12a side). 8), a negative pressure is generated in these two through holes 45 and 46 as well as the relief holes 35 and 36.

  Specifically, the two through holes 45, 46 are formed between the two through holes 45, 46 in the portion of the peripheral wall portion of the large diameter portion 31 b of the relief chamber 31 opposite to the suction chamber 19. The peripheral walls are aligned in the circumferential direction via the valve guide surface portions 41 (see FIG. 6), are substantially at the same position in the longitudinal direction of the relief chamber 31, and open to the mounting surface 12a and the relief chamber 31. It penetrates the part. Both of these two through holes 45 and 46 extend in parallel with the axis P of the pump shaft 15, similarly to the two relief holes 35 and 36. Thus, the two through holes 45 and 46 have a shape that can be molded by the first mold of the split mold, and are formed by the first mold.

  The two through holes 45 and 46 are opposed to the two relief holes 35 and 36 in the direction along the axis P of the pump shaft 15, respectively, and are substantially at the same height as the two relief holes 35 and 36. (See FIG. 5). That is, the two relief holes 35 and 36 and the two through holes 45 and 46 are located at substantially the same position in the longitudinal direction of the relief chamber 31. For this reason, when the relief holes 35 and 36 are closed by the relief valve 33, the through holes 45 and 46 are also closed. When the relief holes 35 and 36 are opened, the through holes 45 and 46 are also opened. . The two through holes 45 and 46 may be slightly shifted in the longitudinal direction of the relief chamber 31 with respect to the two relief holes 35 and 36, but the shift amount is preferably as small as possible.

  In FIG. 6, the right relief hole 35 and the through hole 45 on the side close to the relief hole 35 in the circumferential direction (the right through hole 45 facing the relief hole 35) are formed between the relief hole 35 and the through hole 45. They are connected to each other by a connecting portion 48 formed by cutting out the relief chamber 31 side of the peripheral wall portion of the relief chamber 31 therebetween. That is, the relief hole 35 and the through hole 45 are in communication with each other via the connection portion 48 that is continuous with the space of the relief chamber 31. The connecting portion 48 is formed by the second mold.

  On the other hand, in FIG. 6, the left relief hole 36 and the through hole 46 on the side closer to the circumferential direction with respect to the relief hole 36 (the left through hole 46 facing the relief hole 36) penetrate the relief hole 36. They are separated from each other by the peripheral wall portion of the relief chamber 31 between the holes 46. In other words, the connecting portion 48 as described above is not formed between the relief hole 36 and the through hole 46, and the relief valve guide surface portion 42 is configured with the peripheral wall portion of the relief chamber 31 interposed therebetween. . This is because the bolt insertion hole 22 passes through the peripheral wall portion between the relief hole 36 and the through-hole 46 in the vicinity of the relief chamber 31. This is because the thickness of the surrounding wall portion becomes very thin.

  By forming the relief holes 35 and 36, the through holes 45 and 46, and the connection portion 48, the relief valve 33 is guided by the three relief valve guide surface portions 40 to 42 at the height position of the portion where these are formed. It will be. In other portions of the large-diameter portion 31b, the peripheral wall surface of the large-diameter portion 31b exists all around as a relief valve guide surface.

  Here, as shown in FIGS. 4 and 5, a recess 51 that is recessed in front of the engine (opposite to the mounting surface 12 a) is located above the two through holes 45 and 46 in the mounting surface 12 a of the pump body 12. Is formed so as to connect the two through holes 45 and 46. The recess 51 is formed by the first divided mold. The opening of the recess 51 and the opening of the two through holes 45 and 46 on the mounting surface 51a side are when the pump body 12 is mounted on the pump mounting portion 3b via the mounting surface 12a. The recess 51 is closed by the pump mounting portion 3b, and the opening of the recess 51 and the opening on the mounting surface 12a side of the two through holes 45 and 46 are closed by the pump mounting portion 3b. Sometimes, the two through holes 45 and 46 are formed to communicate with each other.

  Therefore, in this embodiment, when the oil pump 11 is operated, the two relief holes 35 and 36 are set to a negative pressure. Also, one of the two through holes 45, 46 is connected to the relief hole 35 by the connection portion 48, so that the inside of the through hole 45 is set to a negative pressure via the connection portion 48. Further, since the other through hole 46 communicates with the one through hole 45 by the recess 51 formed in the mounting surface 12a, the inside of the through hole 46 also has a negative pressure. As a result, holes 35, 36, 45, 46 that become negative pressure when the oil pump 11 is operated are formed in the peripheral wall portion of the relief chamber 31 in a well-balanced manner in the entire circumferential direction. The biased force no longer acts on the. Therefore, the occurrence of uneven wear of the relief valve 33 is suppressed, and the relief valve 33 operates reliably over a long period of time.

  Further, when the two relief holes 35, 36 are opened by the relief valve 33, the two through holes 45, 46 are also opened. Therefore, in addition to the relief holes 35, 36, the through holes 45, 46 are also used. Oil flows out, but the oil flowing out from the through holes 45 and 46 flows into the suction chamber 19 through the recess 51 and the connecting portion 48, leaks in the middle, and returns to the oil pan. Absent. As a result, a decrease in pump efficiency of the oil pump 11 can be prevented. That is, when the oil is returned to the oil pan, it is necessary to cause the oil pump 11 to perform the extra work of pumping the oil from the oil pan again, and the pump efficiency is reduced by that amount, but the relief holes 35 and 36 and the through holes 45 are reduced. , 46 is returned to the suction chamber 19 so that the pump efficiency can be maintained at the same level as when the through holes 45, 46 are not provided.

(Embodiment 2)
FIG. 9 shows Embodiment 2 of the present invention (note that the same parts as those in FIG. 6 are given the same reference numerals and detailed description thereof is omitted), and the relief hole 36 and the through hole 46 are replaced with the relief hole 35 and The connection is made in the same way as the through hole 45.

  That is, in the present embodiment, the relief hole 35 and the through hole 45 are connected via the connecting portion 48 (hereinafter referred to as the first connecting portion 48) as in the first embodiment, and the relief hole 36 and the through hole 46 are connected. Are connected to each other by a second connection portion 49 formed by cutting out the peripheral wall portion of the relief chamber 31 between the relief hole 36 and the through hole 46 on the relief chamber 31 side. As a result, the relief valve guide surface portion 42 as in the first embodiment does not exist between the relief hole 36 and the through hole 46, and the relief holes 35 and 36, the through holes 45 and 46, and the first and second holes are not provided. At the height position of the portion where the connecting portions 48 and 49 are formed, the relief valve 33 is guided only by the two relief valve guide surface portions 40 and 41.

  As described in the first embodiment, the thickness of the peripheral wall portion between the relief hole 36 and the through hole 46 is very thin due to the presence of the bolt insertion hole 22. Although the size is considerably smaller than that of the first connection portion 48, if there is no bolt insertion hole 22 close to the peripheral wall portion, the size of the second connection portion 49 is the same as that of the first connection portion 48. It is preferable to make it comparable.

  Further, in the present embodiment, since the relief hole 36 and the through hole 46 are connected by the second connecting portion 49, the recess 51 as in the first embodiment is provided on the mounting surface 12a of the pump body 12. Not. However, since the size of the second connecting portion 49 is small, the recess 51 as in the first embodiment may be provided.

  Also in this embodiment, the pump body 12 is cast-molded by the split mold having the first and second molds as in the first embodiment, and the two through holes 45 and 46 are the first of the split molds. The two relief holes 35 and 36 and the first and second connection portions 48 and 49 are formed by one mold (the mold on the mounting surface side), and the split mold second mold (on the side opposite to the mounting surface) is formed. Mold).

  Further, the opening on the mounting surface 12a side in the two through holes 45 and 46 is the same as in the first embodiment, when the pump body 12 is in a state of being attached to the pump mounting portion 3b via the mounting surface 12a. It is closed by the pump mounting portion 3b.

  Therefore, also in the present embodiment, as in the first embodiment, when the oil pump 11 is operated, the inside of the two through holes 45 and 46 is set to a negative pressure via the first and second connection portions 48 and 49. As a result, the force biased to the relief valve 33 by the relief holes 35 and 36 on the suction chamber 19 side (opposite side of the mounting surface 12a) and the through holes 45 and 46 on the side opposite to the suction chamber 19 (side of the mounting surface 12a). Can be prevented from acting. Therefore, the occurrence of uneven wear of the relief valve 33 is suppressed, and the relief valve 33 operates reliably over a long period of time.

  The present invention is useful for an oil pump structure of an engine having a relief hole and a relief valve that opens and closes the relief hole.

It is a front view which shows the cylinder block of the engine main body in an engine with which the oil pump to which the oil pump structure which concerns on Embodiment 1 of this invention was applied was attached. It is the II-II sectional view taken on the line of FIG. It is a front view which shows the pump body of the said oil pump. It is a rear view of the pump body. It is the VV sectional view taken on the line of FIG. It is the VI-VI sectional view taken on the line of FIG. It is a VII direction arrow figure (bottom view) of FIG. It is the VIII-VIII sectional view taken on the line of FIG. FIG. 7 is a diagram corresponding to FIG.

Explanation of symbols

3 Cylinder block 3a front end wall of the engine body (end on one side in the cylinder row direction)
3b Pump mounting portion 11 Oil pump 12 Pump body 12a Mounting surface 15 Pump shaft 16 Inner rotor (pump rotor)
17 Outer rotor (pump rotor)
18 Rotor chamber 19 Suction chamber 20 Discharge chamber 30 Discharge passage 31 Relief chamber 33 Relief valve 35 Relief hole 36 Relief hole 40 Relief valve guide surface part 41 Relief valve guide surface part 45 Through hole 46 Through hole 48 Connection part (first connection part)
49 Second connection 51 Recess P Pump shaft axis

Claims (6)

A pump body provided with a pump shaft driven by a crankshaft of an engine body has a cylinder body row in the engine body via the mounting surface with an end surface on one axial direction of the pump shaft in the pump body as the mounting surface. The suction chamber and the discharge chamber are separated from each other by a rotor chamber in which a pump rotor that is rotated by driving of the pump shaft is disposed at a portion opposite to the mounting surface in the pump body. And a discharge passage that extends from the discharge chamber toward the mounting surface and opens to the mounting surface, and opens to the discharge passage, and A relief chamber extending from the opening so as to pass through the mounting surface side with respect to the suction chamber is formed, and the suction chamber and the relief are formed on a peripheral wall portion of the relief chamber. A relief hole is formed to communicate with the chamber, and a relief valve is provided in the relief chamber to open and close the relief hole by moving in the longitudinal direction of the relief chamber with the peripheral wall surface of the relief chamber as a guide surface. The engine has an oil pump structure for an engine in which a part of the oil discharged from the discharge chamber to the discharge passage is returned to the suction chamber through the relief chamber and the relief hole by opening the relief hole. And
Two relief holes are formed in the circumferential wall portion of the relief chamber on the side of the suction chamber side by side in the circumferential direction with a relief valve guide surface portion therebetween.
The peripheral wall portion of the peripheral wall portion of the relief chamber opposite to the suction chamber is arranged in the circumferential direction with a relief valve guide surface portion therebetween, and the peripheral wall portion is opened to the mounting surface and the relief chamber. Two through holes are formed,
The one relief hole and the through hole on the side close to the relief hole in the circumferential direction are formed by a connection portion formed by cutting out the relief chamber side of the peripheral wall portion of the relief chamber between the relief hole and the through hole. Connected to each other,
The other relief hole and the through hole on the side close to the relief hole in the circumferential direction are separated from each other by a peripheral wall portion of the relief chamber between the relief hole and the through hole,
A recess is formed on the mounting surface,
The opening of the recess and the opening on the mounting surface side of the two through holes are blocked by the engine body when the pump body is mounted to the engine body via the mounting surface. And
The recess is formed so that the two through holes communicate with each other when the opening of the recess and the opening on the mounting surface side of the two through holes are closed by the engine body. An oil pump structure for an engine. The engine oil pump structure according to claim 1,
The pump body is formed by a split mold having first and second molds that are opened and closed in the axial direction of the pump shaft,
The through hole is formed by a first mold on the mounting surface side of the pump body,
The engine oil pump structure according to claim 1, wherein the relief hole is formed by a second mold opposite to the mounting surface of the pump body. The engine oil pump structure according to claim 2,
The engine oil pump structure according to claim 1, wherein the recess is formed by the first mold. A pump body provided with a pump shaft driven by a crankshaft of an engine body has a cylinder body row in the engine body via the mounting surface with an end surface on one axial direction of the pump shaft in the pump body as the mounting surface. The suction chamber and the discharge chamber are separated from each other by a rotor chamber in which a pump rotor that is rotated by driving of the pump shaft is disposed at a portion opposite to the mounting surface in the pump body. And a discharge passage that extends from the discharge chamber toward the mounting surface and opens to the mounting surface, and opens to the discharge passage, and A relief chamber extending from the opening so as to pass through the mounting surface side with respect to the suction chamber is formed, and the suction chamber and the relief are formed on a peripheral wall portion of the relief chamber. A relief hole is formed to communicate with the chamber, and a relief valve is provided in the relief chamber to open and close the relief hole by moving in the longitudinal direction of the relief chamber with the peripheral wall surface of the relief chamber as a guide surface. The engine has an oil pump structure for an engine in which a part of the oil discharged from the discharge chamber to the discharge passage is returned to the suction chamber through the relief chamber and the relief hole by opening the relief hole. And
Two relief holes are formed in the circumferential wall portion of the relief chamber on the side of the suction chamber side by side in the circumferential direction with a relief valve guide surface portion therebetween.
The peripheral wall portion of the peripheral wall portion of the relief chamber opposite to the suction chamber is arranged in the circumferential direction with a relief valve guide surface portion therebetween, and the peripheral wall portion is opened to the mounting surface and the relief chamber. Two through holes are formed,
The one connection hole formed by notching the relief chamber side of the peripheral wall portion of the relief chamber between the relief hole and the through hole, the one through hole and the through hole on the side close to the relief hole in the circumferential direction. Connected to each other by parts
The second relief hole and the through hole on the side close to the relief hole in the circumferential direction are formed by cutting out the relief chamber side of the peripheral wall portion of the relief chamber between the relief hole and the through hole. Connected to each other by parts
The opening on the mounting surface side in the two through holes is closed by the engine body when the pump body is mounted on the engine body via the mounting surface. The engine oil pump structure. The oil pump structure for an engine according to claim 4,
The pump body is formed by a split mold having first and second molds that are opened and closed in the axial direction of the pump shaft,
The through hole is formed by a first mold on the mounting surface side of the pump body,
The engine oil pump structure according to claim 1, wherein the relief hole is formed by a second mold opposite to the mounting surface of the pump body. In the oil pump structure of the engine according to any one of claims 1 to 5,
The engine oil pump structure according to claim 1, wherein the two relief holes and the two through holes are located at substantially the same position in the longitudinal direction of the relief chamber.

Images