JP6591929B2 - Oil pump - Google Patents

Description

  The present invention relates to a variable displacement oil pump.

  As an oil pump for an internal combustion engine, a trochoid type oil pump having an inner rotor connected to a crankshaft directly or via a gear is known. This oil pump has a problem in that the discharge amount per unit time varies depending on the rotation speed of the inner rotor, so that the discharge amount becomes excessive in a high rotation range of the internal combustion engine. In order to solve this problem, a variable displacement oil pump in which a plurality of rotatable vanes are provided in the outer rotor and a control oil passage is provided between the outer peripheral portion of the outer rotor and the housing is known (for example, Patent Document 1). In this oil pump, the control oil passage is connected to the discharge port of the oil pump and has a pressure equal to that of the discharge port. When the oil pressure in the control oil passage rises, each vane receives the oil pressure and is pushed inward in the radial direction of the outer rotor, the volume of the liquid chamber formed between the outer rotor and the inner rotor is reduced, and the oil suction amount is reduced. Decrease. Thereby, the discharge amount of the oil pump is reduced.

JP-A-6-137280

  However, in the oil pump described above, there is a possibility that the liquid chamber expands due to the vane being displaced radially outward under the pressure of the liquid chamber in the vicinity of the discharge port where the volume of the liquid chamber contracts. Therefore, there is a problem that oil tends to remain in the liquid chamber and the volumetric efficiency is low. In addition, since the outer shape of the outer rotor is formed when the vanes rotating independently of each other are in sliding contact with each other, there is a problem that oil is likely to leak from the sliding contact portion of each vane and volume efficiency is low.

  In view of the above background, it is an object of the present invention to improve volumetric efficiency in a variable displacement oil pump.

  In order to solve the above-described problems, an embodiment of the present invention includes a housing (2) in which a rotor housing chamber (7) is formed, and a housing that is rotatable about the first axis (A) in the rotor housing chamber. An outer rotor (3) that is supported and has inner teeth (15) on the inner periphery, and is supported by the housing so as to be rotatable about a second axis (B) that is offset from the first axis inside the outer rotor. And an inner rotor (4) having outer teeth (26) meshing with the inner teeth on the outer periphery, and a region in which a liquid chamber (30) formed between the inner rotor and the outer rotor expands in the rotational direction of the outer rotor. The expansion region (31), and the region where the liquid chamber contracts is the contraction region (32), the housing so as to open toward the liquid chamber in the expansion region. A suction port (34) formed in the groove, a discharge port (36) formed in the housing so as to open toward the liquid chamber in the contraction region, and a valley (15A) of the inner teeth of the outer rotor. ) To the outer peripheral surface (14) of the outer rotor, a plunger (20) slidably received in the through hole, the outer peripheral surface of the outer rotor, and the wall surface of the rotor storage chamber ( 7A), the outer peripheral oil passage (41) connected to the discharge port, and the wall surface of the rotor housing chamber facing the outer peripheral surface of the outer rotor in the contraction region, Provided is an oil pump (1) having a convex portion (40) that pushes inward in the radial direction of the outer rotor.

  According to this aspect, it is possible to provide a variable displacement oil pump with high volumetric efficiency. When the supply amount of the oil pump is small, the pressure at the discharge port is low, so the pressure at the outer peripheral oil passage is low, the plunger moves radially outward by centrifugal force, and the volume of the liquid chamber is increased in the expansion region. To increase. Thereby, the intake amount of the oil pump increases, and as a result, the supply amount of the oil pump increases. On the other hand, when the supply amount of the oil pump is large, the pressure of the discharge port increases, so the pressure of the outer peripheral oil passage increases, and the plunger is in the radial direction against the centrifugal force by the hydraulic pressure supplied from the outer peripheral oil passage. It moves inward and the volume of the liquid chamber decreases in the expansion region. Thereby, the intake amount of the oil pump is decreased, and as a result, the supply amount of the oil pump is decreased. Further, in the contracted region corresponding to the discharge port, the plunger is supported radially inward by the convex portion, so that it can remain in a predetermined position against the pressure of the liquid chamber. Thereby, the volumetric efficiency of the oil pump is improved. Further, since each plunger is slidably accommodated in the through hole, oil leakage from the liquid chamber is suppressed, and the volumetric efficiency of the pump is improved.

  Moreover, said aspect WHEREIN: The said convex part is good to have an inclined surface (40B) from which a protrusion amount increases gradually in the rotation direction of the said outer rotor.

  According to this aspect, the plunger can smoothly move inward in the radial direction of the outer rotor by sliding on the inclined surface.

  Further, in the above aspect, the plunger is movable between an innermost position located on the innermost radial direction with respect to the outer rotor and an outermost position located on the outermost radial direction with respect to the outer rotor. Yes, the convex portion may position the plunger at the innermost position.

  According to this aspect, the volumetric efficiency of the oil pump is improved.

  In the above aspect, the outer rotor may have an inner locking portion (22) that contacts the plunger at the innermost position and restricts the plunger from moving radially inward with respect to the outer rotor.

  According to this aspect, the plunger does not drop out from the through hole inward in the radial direction of the outer rotor.

  In the above aspect, the outer rotor may have an outer locking portion (23) that abuts the plunger at the outermost position and restricts the movement of the plunger outward in the radial direction with respect to the outer rotor.

  According to this aspect, the plunger does not fall out of the outer rotor in the radial direction from the through hole.

  In the above aspect, the outer circumferential surface of the outer rotor is formed with an annular groove (17) recessed radially inward and extending in the circumferential direction, and the through hole opens into the annular groove, and the convex The part is good to have plunged into the annular groove.

  According to this aspect, the sliding contact area between the outer peripheral surface of the outer rotor and the housing can be increased, and the support stability of the outer rotor is improved.

  Moreover, said aspect WHEREIN: The said annular groove is good to comprise at least one part of the said outer periphery oil path.

  According to this aspect, the space for providing the outer peripheral oil passage can be reduced.

  In the above aspect, the through hole may extend in a radial direction of the outer rotor.

  According to this aspect, the plunger can move smoothly by centrifugal force.

  Further, in the above aspect, the housing includes a first housing member (2A) constituting a wall portion on one side in the direction of the first axis of the rotor accommodating chamber, and the first axis of the rotor accommodating chamber. A second housing member (2B) constituting the other wall portion in the direction, and formed in an annular shape, and sandwiched between the first housing member and the second housing member, It has a 3rd housing member (2C) which comprises a wall part, and the said convex part is good to be provided in the internal peripheral surface of the said 3rd housing member.

  According to this aspect, the oil pump can be easily manufactured.

  In the above aspect, the plunger may be formed in a spherical shape.

  According to this aspect, the structure of the plunger can be simplified. Further, the plunger can move smoothly in the through hole.

  According to the above configuration, the volumetric efficiency can be improved in the variable displacement oil pump.

Sectional drawing of the oil pump which concerns on 1st Embodiment II-II sectional view of FIG. The cross-sectional view showing the periphery of the plunger in the expansion region of the oil pump according to the first embodiment The longitudinal cross-sectional view which shows the plunger periphery in the expansion | swelling area | region of the oil pump which concerns on 1st Embodiment. The longitudinal cross-sectional view which shows the plunger periphery in the contraction area | region of the oil pump which concerns on 1st Embodiment. The cross-sectional view showing the periphery of the plunger in the expansion region of the oil pump according to the second embodiment The longitudinal cross-sectional view which shows the plunger periphery in the expansion | swelling area | region of the oil pump which concerns on 2nd Embodiment. Cross-sectional view showing the periphery of the plunger in the expansion region of the oil pump according to the third embodiment The longitudinal cross-sectional view which shows the plunger periphery in the expansion | swelling area | region of the oil pump which concerns on 3rd Embodiment.

  Hereinafter, an embodiment of an oil pump according to the present invention will be described with reference to the drawings. The oil pump 1 according to the embodiment is a variable displacement trochoid pump, and is used for an automobile engine or the like.

(First embodiment)
As shown in FIGS. 1 and 2, the oil pump 1 has a housing 2 and an outer rotor 3 and an inner rotor 4 accommodated in the housing 2.

  The housing 2 has a rotor accommodating chamber 7 inside. The rotor accommodating chamber 7 is formed in a circular hole with the axis A as the center. As shown in FIG. 2, in the present embodiment, the housing 2 includes a first housing member 2 </ b> A, a second housing member 2 </ b> B, and a third housing member 2 </ b> C that are fastened together by screws 8. The third housing member 2C is a plate-like member and is sandwiched between the first housing member 2A and the second housing member 2B. The third housing member 2C is formed with a through-hole 11 having a substantially circular cross section that penetrates in the thickness direction. Each of the first housing member 2 </ b> A and the second housing member 2 </ b> B coaxially has a bottomed recess 12 having a circular cross section at a portion facing the through hole 11. The rotor accommodating chamber 7 is defined by the through hole 11 and each recess 12.

  As shown in FIGS. 1 and 2, the outer rotor 3 is an annular member centered on a predetermined axis, and an outer peripheral surface 14 is formed on the circumferential surface. The outer rotor 3 has inner teeth 15 projecting radially inward on the inner peripheral surface thereof. The internal teeth 15 are formed in a shape based on a trochoid curve. Both end surfaces 16 in the axial direction of the outer rotor 3 are formed on a plane orthogonal to the axial line.

  As shown in FIG. 2, the outer circumferential surface 14 of the outer rotor 3 is formed with an annular groove 17 that is recessed radially inward and that extends in the circumferential direction to form an annular shape. The cross section of the annular groove 17 is formed in a quadrangle having a bottom wall 17A and side walls 17B on both sides of the bottom wall 17A.

  As shown in FIGS. 1 and 3, the outer rotor 3 is formed with a plurality of through holes 18 penetrating from the valley portions 15 </ b> A of the inner teeth 15 on the inner peripheral surface to the outer peripheral surface 14. Each through hole 18 extends linearly along the radial direction of the outer rotor 3. In the present embodiment, the end portion of each through hole 18 on the outer side in the radial direction is open to the bottom wall 17 </ b> A of the annular groove 17. In the present embodiment, the cross section of the through hole 18 is formed in a circular shape.

  Plungers 20 are accommodated in the respective through holes 18 so as to be movable in the longitudinal direction of the through holes 18. In this embodiment, the plunger 20 is a spherical ball. The diameter of the plunger 20 is formed so as to be slidable in contact with the hole wall of the through hole 18. The plunger 20 is preferably formed in a size that allows the through-hole 18 to be liquid-tightly sealed.

  As shown in FIGS. 3 to 5, an inner locking portion 22 projects from the radially inner end of the hole wall of each through hole 18. The inner locking portion 22 contacts the plunger 20 and prevents the plunger 20 from moving inward in the radial direction. When the plunger 20 abuts on the inner locking portion 22, the plunger 20 is at the most radially inner position within the movable range. The position of the plunger 20 at this time is called the innermost position. In the present embodiment, in the innermost position, the plunger 20 is located on the surface formed by the valley portion 15 </ b> A on the inner peripheral surface of the outer rotor 3 at the innermost position. A portion of the inner locking portion 22 that contacts the plunger 20 is formed into a spherical surface.

  An outer locking portion 23 projects from at least one side wall 17B of the annular groove 17. The outer locking portion 23 is in contact with the plunger 20 and prevents the plunger 20 from moving radially outward. When the plunger 20 abuts on the outer locking portion 23, the plunger 20 is at the most radially outer position within the movable range. The position of the plunger 20 at this time is called the outermost position. In the present embodiment, at the outermost position, the portion of the plunger 20 located radially outward is disposed radially inward from the outer peripheral surface 14 of the outer rotor 3. In addition, the plunger 20 has the widest portion located in the through hole 18 at the outermost position to seal the through hole 18. A portion of the outer locking portion 23 that comes into contact with the plunger 20 is formed into a spherical surface. The plunger 20 is movable between the inner locking portion 22 and the outer locking portion 23.

  As shown in FIG. 2, the outer rotor 3 includes a first outer rotor member 3 </ b> A and a second outer rotor member 3 </ b> B that are divided by a virtual plane that is orthogonal to the axis and passes through the center of each through hole 18. The first outer rotor member 3A and the second outer rotor member 3B are fastened to each other by a fastening member such as a bolt. In another embodiment, the movement of the first outer rotor member 3A and the second outer rotor member 3B in the direction perpendicular to the axis is restricted by positioning pins or the like, and the first outer rotor member 3A and the second outer rotor member 3A and the second outer rotor member 3 are controlled by the housing 2 that houses the outer rotor 3. The 2 outer rotor member 3B may be restricted from moving in a direction along the axis. Each plunger 20 is disposed in each through hole 18 when the first outer rotor member 3A and the second outer rotor member 3B are combined.

  As shown in FIGS. 1 and 2, the outer rotor 3 is rotatably accommodated in the rotor accommodating chamber 7 of the housing 2. The outer circumferential surface 14 of the outer rotor 3 is in sliding contact with the circumferential surface of the circumferential wall 7A constituting the outer circumferential portion of the rotor accommodating chamber 7, and the axis of the outer rotor 3 is arranged coaxially with the axis A (first axis) of the rotor accommodating chamber 7. Is done.

  The inner rotor 4 has outer teeth 26 that are disposed inside the outer rotor 3 and inscribed in the inner teeth 15 of the outer rotor 3 in the rotor accommodating chamber 7. The outer teeth 26 are formed in a shape that meshes with the inner teeth 15, and have a smaller number of peaks than the peaks of the inner teeth 15. The axis B (second axis) of the inner rotor 4 is arranged offset in parallel to the axis A of the rotor accommodating chamber 7 and the outer rotor 3. A coupling hole 27 penetrating in the direction along the axis B is formed at the center of the inner rotor 4. An input shaft 28 penetrating the housing 2 is inserted into and coupled to the coupling hole 27. The coupling between the input shaft 28 and the coupling hole 27 may be performed by press-fitting the input shaft 28 into the coupling hole 27 or by coupling via a key.

  When the input shaft 28 rotates with respect to the housing 2, the inner rotor 4 rotates with respect to the housing 2, and the outer teeth 3 rotate with respect to the housing 2 by the inner teeth 15 being pushed by the outer teeth 26. The liquid chamber 30 formed between the outer teeth 26 of the inner rotor 4 and the inner teeth 15 of the outer rotor 3 repeats expansion and contraction according to the rotation of the inner rotor 4 and the outer rotor 3. As shown in FIG. 1, in the rotation direction of the outer rotor 3 (clockwise in FIG. 1, white arrow), an area where the liquid chamber 30 expands is an expansion area 31, and an area where the liquid chamber 30 contracts is a contraction area 32. .

  As shown in FIGS. 1 and 2, the housing 2 has at least one suction port 34 formed so as to open toward at least one liquid chamber 30 in the expansion region 31. In the present embodiment, the suction ports 34 are formed on both sides of the outer rotor 3 and the inner rotor 4 in the axis A direction. The two suction ports 34 extend outward in the radial direction of the housing 2 from the open ends opened to the liquid chamber 30, and are connected to each other in the radial outward direction of the rotor housing chamber 7, and are formed on the outer surface of the housing 2. It is connected to the mouth 35. The suction port 35 is connected to an oil reservoir through an oil passage formed by piping or the like.

  The housing 2 has at least one discharge port 36 formed so as to open toward at least one liquid chamber 30 in the contraction region 32. In the present embodiment, the discharge ports 36 are formed on both sides of the outer rotor 3 and the inner rotor 4 in the axis A direction. The two discharge ports 36 each extend outward in the radial direction of the housing 2 from the open end opened to the liquid chamber 30, are connected to each other in the radial outward direction of the rotor housing chamber 7, and are formed on the outer surface of the housing 2. Connected to outlet 37. The discharge port 37 is connected to a hydraulic device or a sliding portion of the device through an oil passage formed by piping or the like.

  As shown in FIG. 1, in the circumferential wall 7 </ b> A of the rotor accommodating chamber 7, a convex portion 40 that protrudes radially inward and enters the annular groove 17 is formed at a portion corresponding to the contraction region 32. The convex portion 40 extends in the circumferential direction in a range corresponding to the contraction region 32. The protruding end surface 40 </ b> A of the convex portion 40 is formed on a circumferential surface centering on the axis A, and is in sliding contact with the bottom surface of the annular groove 17. Both ends in the circumferential direction of the convex portion 40 are inclined surfaces 40B that are continuous from the wall surface of the circumferential wall 7A to the protruding end surface 40A of the convex portion 40. In the rotation direction of the outer rotor 3, the protruding portion 40 gradually increases by the inclined surface 40B at the end portion on the side where the contraction region 32 starts, and the convex portion 40 by the inclined surface 40B at the end portion on the side where the contraction region 32 ends. The protrusion amount gradually decreases. It is preferable that the projecting end surface 40A of the convex portion 40 and the wall surface of the circumferential wall 7A are smoothly continuous by the inclined surface 40B.

  As shown in FIG. 2, the width of the convex portion 40 is formed narrower than the width of the annular groove 17 in the direction of the axis A. Thus, a passage (space) is formed between the convex portion 40 and each side wall of the annular groove 17. In the present embodiment, the convex portion 40 is formed by the third housing member 2C.

  The annular groove 17 and the circumferential wall 7A cooperate to define an annular outer peripheral oil passage 41 centering on the axis A between the outer rotor 3 and the wall surface of the rotor accommodating chamber 7. The housing 2 opens to a portion of the circumferential wall 7 </ b> A facing the annular groove 17 (that is, the outer peripheral oil passage 41), extends radially outward, and opens to the discharge port 36 outside the rotor accommodating chamber 7. A hydraulic pressure supply path 42 is formed. Thereby, the hydraulic pressure of the discharge port 36 is supplied to the outer peripheral oil passage 41 via the hydraulic pressure supply passage 42, and the pressures of the outer peripheral oil passage 41 and the discharge port 36 become equal. The hydraulic pressure supply path 42 is, for example, a groove formed on the mating surface of the first housing member 2A with the third housing member 2C, or a groove formed on the mating surface of the second housing member 2B with the third housing member 2C. It is good to form by etc.

  The oil pump 1 configured as described above is attached to, for example, an internal combustion engine. The output shaft may be a shaft integrally formed with the crankshaft or a shaft connected to the crankshaft via a transmission mechanism such as a chain, belt, or gear. The suction port 35 is preferably connected to a pipe or the like extending inside the oil pan in which the oil below the internal combustion engine is stored. The discharge port 37 may be connected to the oil passage of the internal combustion engine.

  The operation and effect of the oil pump 1 according to the first embodiment configured as described above will be described. When the input shaft 28 rotates and the inner rotor 4 rotates about the axis B, the outer rotor 3 rotates about the axis A due to the meshing of the outer teeth 26 and the inner teeth 15. When the inner rotor 4 and the outer rotor 3 rotate, the liquid chamber 30 expands in the expansion region 31 and oil is sucked into the liquid chamber 30 from the suction port 34, and the liquid chamber 30 contracts from the liquid chamber 30 in the contraction region 32. Oil is discharged to the discharge port 36. In this way, the oil pump 1 sucks in oil, compresses it, and discharges it.

  Each plunger 20 in the through-hole 18 receives centrifugal force radially outward because the outer rotor 3 rotates. Each plunger 20 receives hydraulic pressure inward in the radial direction by the oil supplied to the outer peripheral oil passage 41 connected to the discharge port 36. The position of each plunger 20 is determined by the centrifugal force and the load received from the hydraulic pressure. When the centrifugal force is larger than the load received from the hydraulic pressure, the plunger 20 moves radially outward and is positioned at the outermost position. On the other hand, when the centrifugal force is smaller than the load received from the hydraulic pressure, the plunger 20 moves inward in the radial direction and is positioned at the innermost position.

  In the low rotation range of the internal combustion engine, the rotation speed of the input shaft 28 is small, the discharge amount per unit time of the oil pump 1 is relatively small, and the hydraulic pressure of the discharge port 36 is relatively low. In this state, the force applied to the plunger 20 becomes larger than the load that the centrifugal force receives from the oil in the outer peripheral oil passage 41, the plunger 20 moves to the outermost position, and the inner end side of the communication passage is a part of the liquid chamber 30. And the liquid chamber 30 expands. As a result, the amount of oil sucked into the liquid chamber 30 from the suction port 34 in the expansion region 31 increases.

  When the rotation of the outer rotor 3 proceeds and the liquid chamber 30 reaches the contraction region 32, the plunger 20 is pushed inward in the radial direction by the convex portion 40 and moved to the innermost position as shown in FIG. As a result, oil radially inward from the plunger 20 in the through hole 18 is pushed out into the liquid chamber 30. Then, the liquid chamber 30 contracts and the oil in the liquid chamber 30 is discharged to the discharge port 36. At this time, since the plunger 20 is supported from the outside in the radial direction by the convex portion 40, even if the liquid chamber 30 contracts and the pressure of the oil in the liquid chamber 30 rises, the plunger 20 does not move in the radial direction. Absent. When the liquid chamber 30 is removed from the contraction region 32, as shown in FIG. 4, the convex portion 40 is detached from the back portion of the plunger 20, and the plunger 20 can move to the outermost position. At this time, if the centrifugal force applied to the plunger 20 is greater than the load applied to the plunger 20 from the oil in the outer peripheral oil passage 41, the plunger 20 moves to the outermost position. Thus, in the low rotation range of the internal combustion engine where the rotation speed of the input shaft 28 is small, the oil pump 1 expands the liquid chamber 30 in the expansion region 31 by the movement of the plunger 20 and increases the amount of oil sucked to discharge the oil. Increase.

  In the high rotation range of the internal combustion engine, the rotation speed of the input shaft 28 is larger than in the low rotation range, the discharge amount per unit time of the oil pump 1 is large, and the hydraulic pressure of the discharge port 36 is large. In particular, the hydraulic pressure of the discharge port 36 increases due to the supply amount being larger than the amount of oil used in each part of the internal combustion engine. The hydraulic pressure of the outer peripheral oil passage 41 is substantially equal to the hydraulic pressure of the discharge port 36. In this state, the load applied to the plunger 20 from the oil in the outer peripheral oil passage 41 is larger than the centrifugal force applied to the plunger 20, the plunger 20 moves to the innermost position as shown by the solid line in FIG. The liquid chamber 30 contracts without contributing to the volume of the liquid chamber 30. Thereby, the amount of oil sucked into the liquid chamber 30 from the suction port 34 in the expansion region 31 is reduced. In the high rotation range, the centrifugal force applied to each plunger 20 increases as the rotational speed of the outer rotor 3 increases. However, the load that the plunger 20 receives radially inward from the oil in the outer peripheral oil passage 41 is applied to the plunger 20. It becomes larger than the applied centrifugal force.

  When the rotation of the outer rotor 3 proceeds and the liquid chamber 30 reaches the contraction region 32, the plunger 20 is supported in the radial direction by the convex portion 40 and remains in the innermost position. Then, the liquid chamber 30 contracts and the oil in the liquid chamber 30 is discharged to the discharge port 36. At this time, since the plunger 20 is supported from the outside in the radial direction by the convex portion 40, even if the liquid chamber 30 contracts and the pressure of the oil in the liquid chamber 30 rises, the plunger 20 does not move in the radial direction. Absent. When the liquid chamber 30 is removed from the contraction region 32, the convex portion 40 is detached from the back portion of the plunger 20, and the plunger 20 can move to the outermost position. At this time, if the centrifugal force applied to the plunger 20 is greater than the load applied to the plunger 20 from the oil in the outer peripheral oil passage 41, the plunger 20 moves to the outermost position. As described above, in the high rotation range of the internal combustion engine where the rotation speed of the input shaft 28 is large, the oil pump 1 contracts the liquid chamber 30 in the expansion region 31 by the movement of the plunger 20, thereby reducing the oil suction amount and the discharge amount. Can be reduced.

  In the oil pump 1 according to the present embodiment, in the contracted region 32 corresponding to the discharge port 36, the plunger 20 is supported radially inward by the convex portion 40, so that the predetermined pressure against the pressure of the liquid chamber 30 is obtained. You can stay in the position. Thereby, the volumetric efficiency of the oil pump 1 is improved. Moreover, since each plunger 20 is slidably accommodated in the through hole 18, oil leakage from the liquid chamber 30 is suppressed, and the volumetric efficiency of the pump is improved.

  Since the convex portion 40 has the inclined surface 40B at the end in the circumferential direction, the plunger 20 can smoothly slide on the convex portion 40 and smoothly move inward in the radial direction of the outer rotor 3.

  Since the annular groove 17 is provided on the outer peripheral surface 14 of the outer rotor 3 and the convex portion 40 is inserted into the annular groove 17, the outer peripheral surface 14 of the outer rotor 3 can be slidably contacted with the outer peripheral wall of the rotor accommodating chamber 7. . Thereby, the slidable contact area between the outer peripheral surface 14 of the outer rotor 3 and the housing 2 is increased, and the support stability of the outer rotor 3 is improved.

  Since the annular groove 17 also serves as the outer peripheral oil passage 41, the space for providing the outer peripheral oil passage 41 can be reduced to reduce the size of the oil pump 1.

(Second Embodiment)
The oil pump 60 according to the second embodiment is different from the oil pump 1 according to the first embodiment in the configuration of the through hole 18, the plunger 20, the inner locking portion 22, and the outer locking portion 23. The configuration of is the same. In the following description of the oil pump 60 according to the second embodiment, the same components as those of the oil pump 1 according to the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIGS. 6 and 7, in the oil pump 60 according to the second embodiment, the through hole 18 is formed in a quadrangular cross section. The plunger 20 is formed in a substantially rectangular parallelepiped and is slidably accommodated in the through hole 18. Locking grooves 61 are respectively provided in the wall surfaces on one side and the other side of the through hole 18 in the axis A direction. Each locking groove 61 extends in the radial direction of the outer rotor 3 and has an inner locking portion 61A formed by a radially inner end wall and an outer locking portion 61B formed by a radially outer end wall. .

  Locking projections 62 project from the wall surfaces on one side and the other side of the plunger 20 in the axis A direction. Each locking projection 62 is received in the corresponding locking groove 61. The innermost position of the plunger 20 is determined when the locking projection 62 contacts the inner locking portion 61A, and the outermost position of the plunger 20 is determined when the locking projection 62 contacts the outer locking portion 61B.

(Third embodiment)
In the oil pump 70 according to the third embodiment, the annular groove 17 is omitted from the outer rotor 3 and the annular groove 71 is formed in the circumferential wall 7A of the housing 2 as compared with the oil pump 1 according to the first embodiment. The point is mainly different. In the following description of the oil pump 70 according to the third embodiment, the same components as those of the oil pump 1 according to the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIGS. 8 and 9, an annular groove 71 having an axis A as the center is recessed in the circumferential wall 7 </ b> A of the housing 2. On the bottom surface of the annular groove 71, a convex portion 72 projecting radially inward is formed at a portion corresponding to the contracted region 32. The convex portion 72 extends in the circumferential direction in a range corresponding to the contracted region 32, similarly to the convex portion 40 according to the first embodiment. The projecting end surface 72 </ b> A of the convex portion 72 is formed on a circumferential surface centered on the axis A and is in sliding contact with the outer circumferential surface 14 of the outer rotor 3. Both ends in the circumferential direction of the convex portion 72 are inclined surfaces (not shown) continuous from the bottom surface of the annular groove 71 to the protruding end surface 72A of the convex portion 72, as in the convex portion 40 according to the first embodiment. In the direction of the axis A, the width of the protrusion 72 is formed smaller than the width of the annular groove 71. The annular groove 71 and the outer peripheral surface 14 of the outer rotor 3 cooperate to define an annular outer peripheral oil passage 73 centering on the axis A.

  The through hole 18 extends linearly from the valley 15 </ b> A of the inner tooth 15 in the radial direction, and opens to the outer peripheral surface 14. The through hole 18 has a circular cross section, and a spherical plunger 20 is slidably accommodated therein. In the oil pump 70, the outer locking portion 23 is omitted from the outer rotor 3. As shown in FIG. 8, in the expansion region 31, the outermost position is defined by the plunger 20 coming into contact with the bottom surface of the annular groove 71. As shown in FIG. 9, in the contraction region 32, the plunger 20 is supported radially inward by the convex portion 72 and is located at the innermost position.

  Although the description of the specific embodiment is finished as above, the present invention is not limited to the above embodiment and can be widely modified. For example, as illustrated in the first to third embodiments, various shapes can be applied to the through hole 18 and the plunger 20. Various shapes can be applied to the inner locking portion 22 and the outer locking portion 23. In the above embodiment, the suction port 34 and the discharge port 36 are provided on both sides of the outer rotor 3 in the direction of the axis A, but may be provided on only one side of the outer rotor 3.

DESCRIPTION OF SYMBOLS 1, 60, 70: Oil pump 2: Housing 2A: 1st housing member 2B: 2nd housing member 2C: 3rd housing member 3: Outer rotor 3A: 1st outer rotor member 3B: 2nd outer rotor member 4: Inner rotor 7: Rotor Accommodating chamber 7A: circumferential wall 14: outer peripheral surface 15: inner teeth 15A: valley 17: annular groove 18: through hole 20: plunger 22: inner locking portion 23: outer locking portion 26: outer teeth 30: liquid chamber 31 : Expansion region 32: Shrinkage region 34: Suction port 36: Discharge port 40: Convex part 40A: Projection end surface 40B: Inclined surface 41: Peripheral oil passage

Claims (10)

A housing in which a rotor housing chamber is formed;
An outer rotor supported by the housing so as to be rotatable about a first axis in the rotor accommodating chamber and having inner teeth on the inner periphery;
An inner rotor provided with outer teeth that are supported by the housing so as to be rotatable around a second axis that is offset with respect to the first axis inside the outer rotor, and that engage with the inner teeth on the outer periphery;
In the rotation direction of the outer rotor, when the liquid chamber formed between the inner rotor and the outer rotor expands as an expansion region, and the region where the liquid chamber contracts is a contraction region, the liquid chamber in the expansion region A suction port formed in the housing so as to open toward the housing, and a discharge port formed in the housing so as to open toward the liquid chamber in the contraction region;
A through hole extending from the valley of the inner tooth of the outer rotor to the outer peripheral surface of the outer rotor;
A plunger slidably accommodated in the through hole;
An outer peripheral oil passage formed between the outer peripheral surface of the outer rotor and a wall surface of the rotor accommodating chamber, and connected to the discharge port and the through hole;
An oil pump, comprising: a convex portion provided on a wall surface of the rotor accommodating chamber facing the outer peripheral surface of the outer rotor in the contraction region and pushing the plunger inward in the radial direction of the outer rotor.   The oil pump according to claim 1, wherein the convex portion has an inclined surface in which a protruding amount gradually increases in a rotation direction of the outer rotor. The plunger is movable between an innermost position located on the innermost radial direction with respect to the outer rotor and an outermost position located on the outermost radial direction with respect to the outer rotor,
The oil pump according to claim 1, wherein the convex portion positions the plunger at the innermost position.   4. The oil pump according to claim 3, wherein the outer rotor has an inner locking portion that abuts on the plunger at the innermost position and restricts movement of the plunger inward in the radial direction with respect to the outer rotor. 5. .   5. The outer rotor includes an outer locking portion that abuts on the plunger at the outermost position and restricts the movement of the plunger radially outward relative to the outer rotor. 6. The oil pump described. On the outer peripheral surface of the outer rotor, an annular groove that is recessed radially inward and extending in the circumferential direction is formed,
The through hole opens in the annular groove,
The oil pump according to any one of claims 1 to 5, wherein the convex portion protrudes into the annular groove.   The oil pump according to claim 6, wherein the annular groove constitutes at least a part of the outer peripheral oil passage.   The oil pump according to any one of claims 1 to 7, wherein the through hole extends in a radial direction of the outer rotor. The housing constitutes a first housing member that constitutes a wall portion on one side in the direction of the first axis of the rotor accommodating chamber, and a wall portion on the other side in the direction of the first axis of the rotor accommodating chamber. A second housing member, and a third housing member formed in an annular shape and sandwiched between the first housing member and the second housing member to form a wall portion of the outer peripheral portion of the rotor accommodating chamber. ,
The oil pump according to any one of claims 1 to 8, wherein the convex portion is provided on an inner circumferential surface of the third housing member.   The oil pump according to any one of claims 1 to 9, wherein the plunger is formed in a spherical shape.

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