JP2014088784A - Variable capacity oil pump - Google Patents

Abstract

An oil pump includes an internal gear pump in which a drive rotor of an external gear and a driven rotor of an internal gear mesh with each other, and supplies oil to a lubricated portion of an engine through at least an oil filter. , The generation of abnormal noise due to discharge pulsation is suppressed.
A displacement adjustment mechanism (for example, an adjustment ring 53, a coil spring 54, an addition ring 53, an addition spring 53), and a pump displacement can be changed by changing relative positions of a drive rotor 51 and a driven rotor 52 with respect to a suction port 50b and a discharge port 50c. Pressure space TH). This capacity adjusting mechanism is configured to operate in response to the hydraulic pressure guided from the oil passage 46 on the downstream side of the oil filter 45.
[Selection] Figure 1

Description

  The present invention relates to a variable displacement oil pump.

  2. Description of the Related Art Conventionally, as disclosed in, for example, Patent Document 1, in an oil pump for supplying engine oil to a lubricated part of an engine or the like, intake ports and discharge ports of an inner rotor (drive rotor) and an outer rotor (driven rotor) It is known that the pump capacity can be changed by changing the positional relationship with respect to.

  This is provided with an adjustment ring that rotatably holds the outer rotor from the outer periphery in the housing. The adjustment ring is operated by hydraulic pressure introduced from the discharge port into the pressurizing space of the housing, and the inner rotor and the outer rotor are pumped. It is designed to be displaced in a decreasing direction.

JP 2012-132356 A

  By the way, in general, in an inscribed gear pump such as a trochoid pump, working chambers are formed between teeth of a drive rotor and a driven rotor, and these working chambers move in the rotational direction of the rotor. The volume increases or decreases. And since the volume change of the working chamber is not uniform with respect to the rotation of the rotor, the pump discharge pressure includes a relatively large pulsation.

  For this reason, when the adjustment ring is operated by the hydraulic pressure introduced from the discharge port as in the conventional example, the adjustment ring is vibrated by the pulsation of the hydraulic pressure, which may cause abnormal noise.

  In view of such problems, an object of the present invention is to suppress the generation of abnormal noise caused by discharge pulsation in a variable displacement internal gear pump used as an oil pump for an internal combustion engine or the like.

  In order to achieve the above object, in the present invention, the hydraulic pressure for operating the pump displacement adjusting mechanism is introduced into the oil pump not from the discharge port but from the downstream oil passage where the pulsation is attenuated.

  Specifically, the present invention comprises an internal gear pump in which a drive rotor of an external gear and a driven rotor of an internal gear mesh with each other, and supplies oil to a lubricated part such as an internal combustion engine through at least an oil filter Is the target. And a displacement adjusting mechanism capable of changing a pump displacement by changing a relative position of the drive rotor and the driven rotor with respect to the suction port and the discharge port. The displacement adjusting mechanism is provided downstream of the oil filter. It is configured to operate under the hydraulic pressure guided from the side oil passage.

  When the oil pump configured as described above is operated, the oil is discharged to the discharge port by the rotation of the drive rotor and the driven rotor, and is supplied to the lubricated portion of the internal combustion engine via an oil filter or the like. In addition, the capacity adjustment mechanism is operated in response to the oil pressure guided from the oil passage on the downstream side of the oil filter, and the oil discharge amount is adjusted.

  Thus, after passing through the oil filter, the discharge pulsation is attenuated, so even if the capacity adjustment mechanism is operated by the hydraulic pressure derived from it, the excitation force acting on the capacity adjustment mechanism is not very large. In other words, the generation of abnormal noise can be suppressed. In addition, since the capacity of the oil pump is adjusted according to the hydraulic pressure on the downstream side closer to the main gallery compared to the upstream side of the oil filter, the controllability such as the oil flow rate and pressure is improved.

  As an example, the capacity adjusting mechanism is introduced into the housing from a holding member that rotatably holds the driven rotor from the outer periphery, a biasing member that biases the holding member in an increasing direction of the pump capacity, and the oil passage. And a hydraulic operation section that operates the holding member in a direction in which the pump capacity decreases against the urging force of the urging member in response to the hydraulic pressure.

  In this configuration, if a large pulsation is included in the hydraulic pressure guided to the capacity adjustment mechanism, a spring or the like that urges the holding member when it is vibrated will expand and contract, which may cause a problem of abnormal noise. The effects of the invention as described above are particularly effective.

  Further, as a preferred configuration, a communication path may be formed in at least one of the drive rotor and the driven rotor so that one end opens on the outer peripheral surface of the tooth tip and the other end opens on the side surface of the rotor. In this way, even if the volume of the working chamber changes suddenly at the final stage where the teeth of the drive rotor and driven rotor mesh with each other, part of the oil can be released to the side of the rotor through the communication path, and the discharge pressure increases rapidly. Can be relaxed to further reduce the excitation force.

  Preferably, if an oil cooler is disposed in the oil passage upstream of the oil filter, the oil pressure pulsation can be further attenuated by passing through the oil cooler. If the oil pressure is taken out from the oil passage downstream from the oil filter and upstream from the main gallery, the length of the passage leading the oil pressure from the take-out portion to the oil pump can be easily shortened.

  According to the variable displacement type oil pump of the present invention, the hydraulic pressure for operating the capacity adjustment mechanism is introduced not from the discharge port but from the downstream oil passage where the pulsation is attenuated. The excitation force does not become so large, and the generation of abnormal noise can be suppressed.

It is sectional drawing which shows the structure of the oil pump which concerns on embodiment of this invention, Comprising: A pump capacity | capacitance shows a maximum state. It is a figure which shows the outline of the oil supply path | route of the engine which concerns on 1st Embodiment. FIG. 2 is a view corresponding to FIG. 1 and showing a state where the capacity of the oil pump is minimal in the first embodiment. It is an image figure which shows that a pulsation attenuate | damps after passing an oil filter. FIG. 3 is a view corresponding to FIG. 1 according to a second embodiment. It is an expanded sectional view of the tooth tip which shows the structure of a relief hole. It is explanatory drawing that a pulsation becomes small by an escape hole.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, the case where the present invention is applied to a gasoline engine 1 (internal combustion engine) for an automobile will be described, but the present invention is not limited to this. The description of this embodiment is merely an example, and does not limit the configuration or use of the present invention.

(First embodiment)
FIG. 1 shows the structure of the oil pump 5 according to the first embodiment, and FIG. 2 shows an outline of the oil supply path 4 of the engine 1. As shown in phantom lines in FIG. 2, the engine 1 has an engine block 2 in which a cylinder head is assembled to the upper part of the cylinder block and a crankcase is assembled to the lower part, and an oil pan 3 is attached to the lower part thereof. ing.

  In the present embodiment, the engine oil (hereinafter also simply referred to as oil) stored in the oil pan 3 is sucked up by the operation of the oil pump 5, and the pistons, crank bearings, valve trains and the like are lubricated by the oil supply path 4. Supply to the cooling part That is, the oil recirculated from the lubricated part or the like is stored in the oil pan 3, and the oil strainer 41 is disposed so as to be immersed in the oil.

  The suction pipe 41 a of the oil strainer 41 is connected to the suction port 50 b of the oil pump 5. The oil pump 5 is an internal gear pump including an external gear drive rotor 51 and an internal gear driven rotor 52, which will be described later in detail, and is provided at the center of the drive rotor 51 as shown in FIG. Driven by the fitted crankshaft 6, the oil in the oil pan 3 is sucked up through the oil strainer 41.

  On the other hand, the upstream end of the first oil passage 42 formed in the engine block 2 communicates with the discharge port 50 c of the oil pump 5, and the downstream end of the first oil passage 42 is connected to the oil cooler 43. . The oil cooler 43 cools the oil by exchanging heat with the engine cooling water. The cooled oil flows through the second oil passage 44 formed in the engine block 2 and is sent to the oil filter 45.

  The oil filter 45 filters foreign matters and impurities in the oil by the filter element, and the filtered oil flows through the third oil passage 46 and is sent to the main gallery 47. The main gallery 47 is formed in the engine block 2 so as to extend, for example, in the cylinder row direction, and maintains a predetermined pressure of the oil sent as described above, and a plurality of oil passages branching therefrom. (Not shown) to distribute to the above-mentioned lubricated parts.

-Structure of oil pump-
Next, the structure of the oil pump 5 will be described in detail with reference to FIG. As shown in the figure, the oil pump 5 holds an external gear drive rotor 51 rotated by the crankshaft 6, an internal gear driven rotor 52 rotated in mesh with the external gear, and the driven rotor 52 rotatably held from the outer periphery. The adjustment ring 53 (holding member) to be housed is accommodated in the housing 50. The adjustment ring 53 is for changing the pump capacity by displacing the drive rotor 51 and the driven rotor 52 as will be described later.

  First, the housing 50 has a thick plate shape as a whole. As shown in FIG. 1, the housing 50 is shaped like a long bowl in a plan view, and has a deformed recess 50a that opens to the front side (front side in the figure). Is formed. The recess 50a accommodates the drive rotor 51, the driven rotor 52, the adjustment ring 53, and the like (hereinafter referred to as an accommodation recess 50a), and is closed by overlapping and fastening a cover (not shown) from the front. .

  A round hole (not shown) penetrating the bottom wall of the housing recess 50a is formed at a position slightly above the center of the housing recess 50a, and the front end of the crankshaft 6 is inserted therethrough. Although not shown, a similar through hole is also formed in the cover, and the front end portion of the crankshaft 6 is inserted into the through hole, and can be rotated by a bearing bush disposed in each hole. It is supported by.

  Further, the front end portion of the crankshaft 6 is provided with a D-cut portion having a part of its outer peripheral surface as a flat surface, and is fitted into a central hole 51b that penetrates the central portion of the drive rotor 51 to rotate integrally. It is like that. The drive rotor 51 has a plurality of external teeth 51a (seven in the example shown in the figure) having a trochoid curve or a curve approximated to a trochoid curve (for example, involute, cycloid, etc.) on the outer periphery.

  On the other hand, the driven rotor 52 is formed in an annular shape, and the inner teeth 52a are formed on the inner circumference thereof so as to mesh with the outer teeth 51a of the drive rotor 51 (eight in the illustrated example). Has been. The center of the driven rotor 52 is eccentric by a predetermined amount with respect to the center of the drive rotor 51, and the outer teeth 51 a of the drive rotor 51 and the inner teeth 52 a of the driven rotor 52 on the eccentric side (lower right side in the figure). Are engaged.

  Further, the outer peripheral surface of the driven rotor 52 is slidably fitted to and supported by the main body portion 53a with a slight gap between the outer peripheral surface and the inner peripheral surface of the main body portion 53a of the adjustment ring 53. That is, the adjustment ring 53 holds the driven rotor 52 so as to be rotatable from the outer periphery. The ring main body 53a is integrally formed with a protruding portion 53b that is partially extended outward, an arm portion 53c that extends radially outward, and a tapered protruding portion 53d. Yes.

  The drive rotor 51 and the driven rotor 52 thus held by the adjustment ring 53 constitute a trochoid pump of seven leaves and eight nodes in this embodiment, and in the annular space between the two rotors 51 and 52, A plurality of working chambers R arranged in the circumferential direction are formed between the teeth meshing with each other. The volume of each working chamber R increases or decreases while moving along the outer periphery of the drive rotor 51 as the two rotors 51 and 52 rotate.

  That is, in a range from the position where the teeth of the two rotors 51 and 52 mesh with each other (in the vicinity of the base of the arm portion 53c of the adjustment ring 53 in FIG. 1) to about 180 degrees in the rotor rotation direction indicated by the arrow in the drawing, As the rotors 51 and 52 rotate, the volume of the working chamber R gradually increases, and a suction range for sucking oil is obtained. On the other hand, in the remaining range of about 180 degrees, the volume of the working chamber R gradually decreases as the rotors 51 and 52 rotate, and becomes a discharge range in which oil is discharged while being pressurized.

  A suction port 50b and a discharge port 50c are formed in the housing 50 so as to correspond to the suction range and the discharge range, respectively. As an example, in this embodiment, the suction port 50b is opened at the bottom surface of the housing recess 50a of the housing 50 so as to correspond to the suction region as shown by a part of broken lines in FIG. The discharge port 50c is open.

  The suction port 50b is curved and extended toward the outer periphery of the housing 50 (downwardly to the left in the figure) and communicates with the suction pipe 41a of the oil strainer 41. The discharge port 50c is also connected to the outer periphery of the housing 50 (see FIG. The first oil passage 42 communicates with the first oil passage 42. When the drive rotor 51 and the driven rotor 52 rotate while meshing with each other, oil is sucked from the suction port 50b into the working chamber R formed between them, pressurized and discharged from the discharge port 50c.

  Since the flow rate of the oil discharged from the discharge port 50c increases as the rotational speed of the oil pump 5, that is, the engine rotational speed increases, the amount of oil supplied to the lubricated portion of the engine 1 in the high rotational speed increases. Even in this case, the main gallery 47 can maintain a hydraulic pressure higher than a predetermined level, and can properly distribute the oil to the lubricated portion.

-Capacity adjustment mechanism-
Furthermore, the oil pump 5 of this embodiment includes a capacity adjustment mechanism that can change the flow rate of oil discharged per rotation of the drive rotor 51, that is, the pump capacity. In the present embodiment, the adjustment ring 53 is operated to change the relative positions of the drive rotor 51 and the driven rotor 52 with respect to the suction port 50b and the discharge port 50c. change.

  Specifically, as shown in FIG. 1, the pressing force from the compression coil spring 54 (biasing member) acts on the arm portion 53 c that extends radially outward from the main body portion 53 a of the adjustment ring 53. As a result, the adjustment ring 53 is biased so as to be displaced upward while rotating counterclockwise in the figure. Further, guide pins 50d and 50e project from the bottom surface of the housing recess 50a of the housing 50, and come into contact with the inner peripheral surface of the protruding portion 53b and the outer peripheral surface of the protruding portion 53d of the adjustment ring 53, respectively. The operation of 53 is guided.

  The adjustment ring 53 guided in this manner divides the inside of the housing recess 50a into an upper pressurizing space TH and a lower low pressure space TL in the figure, and the hydraulic pressure in the pressurizing space TH (hydraulic operating portion). Operated in response to F. That is, the pressurizing space TH is communicated with the third oil passage 46 between the oil filter 45 and the main gallery 47 through the pilot passage 50 f, and the hydraulic pressure is guided from the third oil passage 46.

  The hydraulic pressure thus guided acts on the upper outer peripheral surface of the adjustment ring 53 facing the pressurizing space TH, and a downward pressing force F is applied as shown by a white arrow in the figure. On the other hand, since the atmospheric pressure is generally applied to the low pressure space TL communicating with the suction port 50b, the adjusting ring 53 receives the elastic force of the coil spring 54 acting on the arm portion 53c as described above, and moves upward. On the other hand, it is pressed downward by the oil pressure F from the pressurizing space TH, and is operated in a balance between the two.

  When the adjustment ring 53 is positioned at the uppermost position as shown in FIG. 1, the amount of oil sucked from the suction port 50b and discharged from the discharge port 50c per one rotation of the drive rotor 51 and the driven rotor 52, that is, the pump Capacity is maximized. On the contrary, when the adjustment ring 53 is located at the lowermost position as shown in FIG. 3, the pump capacity is minimized.

  With such a configuration, for example, when the engine speed is low, such as idling, the adjustment ring 53 is urged to the uppermost position as shown in FIG. 1 by the elastic force of the coil spring 54, and the pump capacity is maximized. When the engine speed increases from this state, the pump discharge pressure increases, so the hydraulic pressure introduced into the pressurizing space TH also increases, and the adjustment ring 53 operates downward against the resilient force of the coil spring 54. .

  As the adjustment ring 53 operates downward and the pump capacity decreases, the degree of increase in the oil discharge amount due to the increase in the rotational speed decreases, and an appropriate amount of oil is supplied to the main gallery 47. Become so. Then, when the engine speed is very high, the pump capacity is minimized as shown in FIG. 3, so that excessive oil supply to the main gallery 47 is suppressed.

  By the way, in the above-described oil pump 5, in general, the adjustment ring 53 generally guides a part of the opening of the discharge port 50 c to the pressurizing space TH in the housing 50 and guides the discharge pressure to the pressurizing space TH as it is. Had to work. However, in this case, the pulsation included in the discharge pressure vibrates the adjustment ring 53, and the arm portion 53c and the like collide with the housing recess 50a and the guide pins 50d and 50e, and noise may be generated. .

  On the other hand, in the present embodiment, the hydraulic pressure is guided from the third oil passage 46 between the oil filter 45 and the main gallery 47 as described above, and in this third oil passage 46, the oil cooler 43 and the oil Since the pulsation is attenuated by passing through the filter 45, the excitation force acting on the adjustment ring 53 is reduced, and the generation of abnormal noise can be suppressed.

  FIG. 4 (a) shows the result of examining the change in hydraulic pressure (discharge pressure) of the discharge port 50c, and FIG. 4 (b) shows the change in hydraulic pressure after passing through the oil filter 45. Yes. Comparing both figures, a large discharge pulsation at the discharge port 50c is attenuated by passing through the oil cooler 43 and the oil filter 45, and the pulsation is considerably reduced in the third oil passage 46 on the downstream side of the oil filter 45. I understand.

  As described above, in the oil pump 5 of the engine 1 according to the present embodiment, in order to change the pump capacity by displacing the drive rotor 51 and the driven rotor 52, the hydraulic pressure applied to the adjustment ring 53 is conventionally conventional. The oil is introduced not from the discharge port 50c but from the third oil passage 46 on the downstream side through which the pulsation is attenuated through the oil cooler 43 and the oil filter 45. For this reason, the exciting force to the adjustment ring 53 does not become so large, and the generation of abnormal noise can be suppressed.

  Moreover, since the capacity of the oil pump 5 can be adjusted according to the hydraulic pressure on the downstream side closer to the main gallery 47 as compared to the upstream side such as the oil filter 45, the controllability such as the oil flow rate to the main gallery 47 is improved. Even if the amount of oil supplied to the lubricated portion of the engine 1 changes greatly, the hydraulic pressure of the main gallery 47 can be suitably maintained.

  Further, the third oil passage 46 downstream from the oil filter 45 and upstream from the main gallery 47 is formed so as to pass in the vicinity of the oil pump 5 in the engine block 2, so that the hydraulic pressure is supplied from here. The length of the pilot passage 50f that is taken out and led to the oil pump 5 can be easily shortened, and this is also advantageous in improving controllability.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the second embodiment, the outer teeth 51a of the drive rotor 51 of the oil pump 5 and the inner teeth 52a of the driven rotor 52 are respectively escape holes 51c for releasing a part of the hydraulic pressure that rapidly rises in the working chamber R. 52b is provided. Since the other configuration is the same as that of the first embodiment, the escape holes 51c and 52b will be mainly described here.

  FIG. 5 is a cross-sectional view showing the structure of the oil pump 5 in the present embodiment, and shows a state where the pump capacity is maximum as in FIG. FIG. 6A shows the drive rotor 51 and the driven rotor 52 in an enlarged manner, and the escape holes 51c and 52b have one ends including the apexes of the teeth 51a and 52a as shown in FIG. It opens to the outer peripheral surface of the tooth tip, branches after extending toward the tooth root, and opens to both sides of the rotor.

  That is, when the outer teeth 51a of the drive rotor 51 and the inner teeth 52a of the driven rotor 52 mesh with each other, the relief holes 51c and 52b are formed between the outer peripheral surface of the tooth tip and the inner peripheral surface of the tooth base that are close to each other in the final stage. This is a communication path that communicates the gap with the side surface of the rotor. FIG. 6 (b) shows an example in which the relief holes 51c and 52b are opened at one place on the outer peripheral surface of the tooth tip. This is because the openings are opened at two places as shown in FIG. 6 (c). It may be.

  By providing such escape holes 51c and 52b, the discharge pulsation of the oil pump 5 is alleviated, and the excitation force applied to the adjustment ring 53 can be further reduced. That is, in the final stage where the outer teeth 51a of the drive rotor 51 and the inner teeth 52a of the driven rotor 52 are engaged, the volume of the working chamber R is rapidly reduced between the outer peripheral surface of the tooth tip and the inner peripheral surface of the tooth root. As schematically shown in FIG. 7A, the discharge pressure rises in a steep pulse shape.

  On the other hand, if the relief holes 51c and 52b opened on the outer peripheral surface of the tooth tip are provided as in the present embodiment, the relief holes 51c and 52b are released from the working chamber R in which the volume rapidly decreases at the final stage of meshing as described above. The hydraulic pressure can be released. For this reason, as shown in FIG. 7B, the rise of the pulsed discharge pressure becomes low, and the increase in discharge pulsation can be mitigated.

  Therefore, in the case of the oil pump 5 according to the second embodiment, the hydraulic pressure for operating the adjustment ring 53 is introduced from the third oil passage 46 in which the pulsation is attenuated, as in the first embodiment described above, Further, by reducing the discharge pulsation itself, the excitation force applied to the adjustment ring 53 can be further reduced, and the generation of abnormal noise can be more reliably suppressed.

-Other embodiments-
Each of the embodiments described above has been described with respect to the case where the present invention is applied to the oil pump 5 of the in-line four-cylinder gasoline engine 1 for automobiles. However, the present invention is not limited to this, and is applicable to engines other than automobiles. It can also be applied to oil pumps. Further, the number of cylinders and the type of engine (V type, horizontally opposed type, etc.) are not particularly limited, and the present invention can be applied to an oil pump of a diesel engine. Furthermore, the present invention can be applied to an oil pump of a transmission.

  In each of the above embodiments, the hydraulic pressure is taken out from the third oil passage 46 after passing through the oil cooler 43 and the oil filter 45 and introduced into the pressurizing space TH in the housing 50 of the oil pump 5. However, the present invention is not limited to this. For example, the oil cooler 43 may not be provided. Further, the hydraulic pressure may be taken out from the main gallery 47, or the hydraulic pressure may be taken out from an oil passage on the downstream side of the main gallery 47.

  Further, the capacity adjustment mechanism of the oil pump 5 is not limited to the one provided with the adjustment ring 53, the coil spring 54, and the like as in the above embodiments, and various other configurations are conceivable.

  Furthermore, in the second embodiment, escape holes 51c and 52b are provided in the tooth tips of both the external teeth 51a of the drive rotor 51 and the internal teeth 52a of the driven rotor 52, but the external teeth 51a or the internal teeth 52a are provided. Only one of the relief holes 51c and 52b may be provided. Further, the escape holes 51c and 52b do not reach both sides of the rotor but may communicate with either one of the side surfaces.

  Since the present invention can suppress the generation of abnormal noise from the engine or transmission oil pump, it is highly effective when applied to an engine mounted on an automobile.

1 engine (internal combustion engine)
4 Oil supply system 43 Oil cooler 45 Oil filter 46 Third oil passage (oil passage downstream of the oil filter)
47 Main Gallery 5 Oil Pump 50 Housing 50b Suction Port 50c Discharge Port 51 Drive Rotor 51a External Teeth 51c Relief Hole (Communication Path)
52 Driven rotor 52a Internal tooth 52b Relief hole (communication path)
53 Adjustment ring (holding member: capacity adjustment mechanism)
54 Coil spring (Biasing member: Capacity adjustment mechanism)
TH pressurization space (hydraulic operating part: capacity adjustment mechanism)

Claims (5)

An oil pump comprising an internal gear pump in which a drive rotor of an external gear and a driven rotor of an internal gear mesh with each other, and supplies oil to a lubricated part through at least an oil filter,
A displacement adjusting mechanism capable of changing a pump displacement by changing a relative position of the drive rotor and the driven rotor with respect to a suction port and a discharge port;
2. The variable displacement oil pump according to claim 1, wherein the displacement adjusting mechanism is configured to operate by receiving a hydraulic pressure guided from an oil passage downstream of the oil filter. The variable displacement oil pump according to claim 1, wherein
The capacity adjustment mechanism is
A holding member for rotatably holding the driven rotor from the outer periphery;
An urging member that urges the holding member in a direction in which the pump capacity increases;
Receiving a hydraulic pressure introduced into the housing from the oil passage, and operating the holding member in a direction in which the pump capacity decreases against the biasing force of the biasing member;
Equipped with a variable displacement oil pump. The variable displacement oil pump according to any one of claims 1 and 2,
A variable displacement oil pump, wherein at least one of the drive rotor and the driven rotor is formed with a communication path such that one end opens on the outer peripheral surface of the tooth tip and the other end opens on the side surface of the rotor. In the variable displacement oil pump according to any one of claims 1 to 3,
A variable displacement oil pump, wherein an oil cooler is disposed in an oil passage upstream of the oil filter. In the variable displacement oil pump according to any one of claims 1 to 4,
Equipped with internal combustion engine,
A variable displacement oil pump in which hydraulic pressure guided to the capacity adjusting mechanism is taken out from an oil passage downstream of the oil filter and upstream of a main gallery of the internal combustion engine.

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