JP6066709B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine in which a chain cover that covers a transmission mechanism for a valve mechanism such as a timing chain is also used as a part of an oil pump (trochoid pump). Note that gears and timing belts can also be used as the transmission mechanism for the valve operating mechanism. Therefore, strictly speaking, the term “chain cover” does not match the gears and timing belt, but the term “chain cover” is used. In this application, the wording of the chain cover is used as a broad concept cover that covers the transmission means.

  As an oil pump for an internal combustion engine for a vehicle, a trochoid pump having an inner rotor and an outer rotor whose rotational axes are shifted is generally used because of its small size and high output. This trochoid oil pump has a structure in which a pair of meshed inner rotor and outer rotor is sandwiched between a pump housing and a pump cover. The inner rotor is directly connected to the crankshaft and the rotational power of the crankshaft. Is transmitted to the inner rotor by a chain or a gear, and the crankshaft direct connection method is an advantage that can be made compact.

  Examples of the type in which the inner rotor is directly connected to the crankshaft include, for example, Patent Documents 1 and 2, and in Patent Document 2, a chain cover that covers the valve mechanism driving timing chain is also used as a pump housing part. . If a part of the pump cover is also used as a component of the oil pump as in Patent Document 2, the oil pump is further reduced in size.

  In any case, the oil pump has a relief passage that allows oil to escape when the discharge pressure becomes excessive, and if a relief valve that is biased by a spring is placed in the relief passage, the discharge pressure becomes excessive. Oil is supposed to escape. And in patent document 1, since the relief oil was returned to the oil pan conventionally, in view of the large mechanical loss of the oil pump, by opening the end of the relief passage to the suction passage, It is described to reduce the mechanical loss of the pump.

Japanese Patent Publication No. 07-88820 JP 2002-48075 A

  Now, the trochoid pump confins oil in the space between the inner rotor and outer rotor, and pumps it, but since oil is pumped intermittently, pressure fluctuations occur in the discharge pressure, which is Appears as pulsation.

  Patent Document 2 is an invention aimed at attenuating the pulsation of the discharged oil itself, but the oil pulsation also occurs in the relief passage. As in Patent Document 2, the relief oil is supplied to the oil pump. When returning to the suction passage, there is a possibility that noise may be generated by the relief oil returned from the relief passage and the sealing performance of the oil pump may be adversely affected. In particular, since the relief oil returning from the relief passage is at a high pressure, it can be said that problems of noise and deterioration of sealing performance due to the pulsation of the relief oil are likely to appear remarkably.

  The present invention has been made to improve such a current situation, and aims to effectively suppress problems such as noise caused by pulsation of relief oil with a simple structure.

  An internal combustion engine of the present invention includes a cylinder block having a crankshaft protruding from one side surface, a chain cover that is fixed to one side surface of the cylinder block and covers a transmission mechanism for a valve mechanism that is driven by the crankshaft, And an oil pump driven by a crankshaft.

An oil suction passage and a discharge passage are formed on the mating surface of the pump housing portion and the pump cover, and a relief passage for allowing the discharged oil to escape to the suction passage when the oil discharge pressure becomes excessive. the via pump cover so formed as to return to the suction passage, the portion formed in the pump cover of the relief passage, the relief valve for opening and closing the relief passage is arranged movably And
Accordingly, the relief passage has a first portion into which the discharged oil flows, a second portion in which the relief valve moves, and a third portion in communication with the second portion and the suction passage. , the pump portion formed by the housing portion of the inner surface of the suction passage, the oil ejected from part 3 content of the relief passage is in those barrels oil contact surface.

Then, Part 3 content of the relief passage is, while being formed closer to the side close to the first part portion of the relief passage of the suction passage,
The oil abutment surface, relative to the pump housing portion and the mating surface of the pump cover is inclined away from said mating face with increasing distance from the first part portion of the relief passage,
In addition, the axis of the third portion of the relief passage is inclined with respect to the oil contact surface so as to move away from the first portion of the relief passage as the oil contact surface is approached.

  As a result of investigations by the inventors of the present application, it is estimated that noise when oil is relieved is mainly caused by the oil ejected from the relief passage colliding with the inner surface (wall surface) of the suction passage. That is, since the oil ejected from the relief passage collides with the inner surface of the suction passage vigorously, film vibration is generated in the chain cover constituting the suction passage, and this is presumed to be a cause of noise.

On the other hand, in the present invention, the oil jetted from the end (third portion) of the relief passage is deflected in the flow direction at the oil contact surface of the suction passage, so that the kinetic energy of the oil is changed to the inner surface of the suction passage. Therefore, even if there is pulsation in the oil, it is possible to prevent or remarkably suppress the vibration of the chain cover, which may cause noise during oil relief. It is possible to prevent or remarkably suppress the deterioration of the sealing performance.

  Further, since the vibration is suppressed by devising the shape of the suction passage instead of providing a braking member, the structure is simple and beneficial in terms of cost.

1 is a side view of an internal combustion engine according to an embodiment. The chain cover implementation form is a perspective view from the outside. It is a separation figure of a chain cover and a pump cover, and the chain cover is seen from the back side. (A) is a schematic cross-sectional view taken along the line IVA-IVA in FIG. 1, and (B) is a schematic cross-sectional view taken along the line IVB-IVB in FIG. In drawing showing the essential components of the implementation form, C-C of (A) VA-VA sectional view of FIG. 3, (B) is VB-VB cross-sectional view of FIG. 3, is (C) is (B) (D) is a DD cross-sectional view of (C).

(1). Summary of the implementation forms will be described with reference to the embodiment of the present invention with reference to the drawings. This embodiment is applied to an internal combustion engine for a vehicle. As shown in FIG. 1, the internal combustion engine includes a cylinder block 3 having a cylinder bore 2 in which a piston 1 reciprocates, and a cylinder fixed to the upper surface of the cylinder block 3. A head 4 and a chain cover 5 fixed to one side of the cylinder block 3 and the cylinder head 4 are provided. An oil pan 6 is fixed to the lower surface of the cylinder block 3. On the other hand, a cylinder head cover 7 is fixed to the upper surface of the cylinder head 4.

  In the following description, in order to specify the direction, left and right and inner and outer words are used, and these left and right words are based on FIG. Further, with respect to the inner side and the outer side, when the chain cover 5 is used as a reference, the direction facing the cylinder block 3 is called the inner side, and the exposed side opposite to the cylinder block 3 is called the outer side. In this embodiment, FIG. 1 is a front view. Therefore, the side view is as seen from the horizontal direction orthogonal to the axis of the crankshaft 8.

As shown in FIGS. 2 and 4A, the chain cover 5 has a peripheral wall 5a and has a shallow tray shape that opens toward the cylinder block 3 and the cylinder head 4. A shaft hole 9 through which the crankshaft 8 passes is vacant. As shown roughly in FIG. 4B, an accessory drive pulley 10 is fixed to a portion of the crankshaft 8 exposed from the chain cover 5 and the accessory drive wound around the accessory drive pulley 10 is fixed. An auxiliary machine such as an alternator or a water pump is driven by the belt 11.

The portion of the chain cover 5 that extends to the left and right sides with the shaft hole 9 as the center is a pump housing portion 12 that constitutes a part of the oil pump, and the pump cover 13 is superimposed on the pump housing portion 12 from the inside. The pump cover 13 is fixed to the pump housing portion 12 with a group of bolts 14 (see FIG. 4A). In FIG. 4 (B), the pump cover 13 is shown schematically. As shown in FIG. 4A, a portion of the pump cover 13 around the crankshaft 8 is recessed, and a sprocket 8a fixed to the crankshaft 8 is formed in the recessed portion as shown in FIG. 4B. The timing chain 8b is wound around the sprocket 8a.

  As shown in FIG. 4, a pump chamber 15 that is recessed outside the pump cover 13 is formed at a location around the crankshaft 8 in the pump housing portion 12, and an inner rotor that meshes with the pump chamber 15. 16 and the outer rotor 17 are arranged. Accordingly, an oil pump 18 is configured by a part of the chain cover 5, the pump cover 13, and the rotors 16 and 17. Needless to say, the crankshaft 8 passes through the pump cover 13.

The mating surfaces of the pump housing 12 and the pump cover 13, a suction passage 19 for guiding the oil into the pump chamber 15, and a discharge passage 20 for discharging the pressurized oil, is formed so as to face in the lateral direction opposite ing. Suction passage 19 and the discharge passage 20 is formed by denting both the pump housing 12 and pump cover 13.

  Although not shown in the drawing, the outer periphery of the inner rotor 16 and the inner periphery of the outer rotor 17 are formed with concavities and convexities that mesh with each other. The outer peripheral surface of the outer rotor 17 is a perfect circle, but the rotational axis of the inner rotor 16 and the rotational axis of the outer rotor 17 are slightly shifted from each other. The oil is intermittently pumped from 19 to the discharge passage 20.

  As shown in FIGS. 3 and 5, an oil introduction passage 21 extending downward is integrally formed in a portion of the pump cover 13 opposite to the pump housing portion 12, and the end of the oil introduction passage 21 is a suction port. The passage 19 generally communicates with the left and right intermediate portions. A suction unit having a strainer is fixed to the oil introduction passage 21.

  The oil that has exited the discharge passage 20 once reaches the oil filter 22, then returns to the relay passage 23 shown in FIG. 3, and is sent from the pipe-like discharge passage 24 to an oil feed passage such as an oil gallery. The tip of the discharge passage 24 can be brought into contact with an oil feed passage formed in the cylinder block 3.

  As clearly shown in FIG. 2, a filter holding portion 25 is formed at the end of the chain cover 5, and a screw cylinder 26 into which the oil filter 22 is screwed protrudes outwardly from the filter holding portion 25. Yes. The screw cylinder 26 is parallel to the crankshaft 8, and therefore, the oil filter 22 is also arranged in a lateral orientation substantially parallel to the crankshaft 8. An annular groove 27 located outside the screw cylinder 26 is formed on the outer surface of the filter holding portion 25, and a relay hole 28 communicating with the relay passage 23 is formed at the location of the annular groove 27.

(2) Relief means As shown in FIGS. 3 and 5, the pump housing part 12 and the pump cover 13 have a relief passage 29 for returning the oil to the suction passage 19 when the oil discharge pressure becomes higher than a set value. Is formed. The relief passage 29, when communicating with the discharge passage 20 through the pump chamber 15 and the first portion 29a extending in the same direction as the suction passage 19 into co, second portion formed in a posture substantially parallel to the oil introduction passage 21 29b, a second portion 29b, and a third portion 29c communicating with the suction passage 19.

  The first portion 29 a of the relief passage 29 is formed by a groove provided in both the pump housing portion 12 and the pump cover 13, and the second portion 29 b is formed by providing the cylinder portion 30 in the pump cover 13. The third portion 29 c is formed by making a hole in the pump cover 13. The cylindrical portion 30 is inclined so as to be away from the mating surface 39 of the pump housing portion 12 and the pump cover 13 as it goes downward in a side view. In other words, the cylindrical portion 30 is inclined so as to approach the cylinder block 3 (or move away from the chain cover 5) as it goes downward.

A rod-shaped relief valve 31 is fitted into the cylindrical portion 30 and the relief valve 31 is biased upward by a spring 32. The upper end portion of the second portion 29b of the relief passage 29 is a small diameter portion 29b ' , and the relief passage 29 is blocked by the relief valve 31 hitting the lower surface of the small diameter portion 29b'. The spring 32 is supported by a spring receiver 33, and the spring receiver 33 is held by a supporting means such as a split pin 34 so that it cannot be removed.

The third portion 29c of the relief passage 29 corresponds to a terminal portion, and in the present embodiment, the third portion 29c is provided at two front and rear positions in a side view (of course, orthogonal to the axis 35 of the cylindrical portion 30). Only one place may be provided at the place of the line. Further, as shown in FIGS. 5B and 5C, the third portion 29 c of the relief passage 29 is formed so as to open toward the side closer to the first portion 29 a of the relief passage 29 in the suction passage 19. Yes.

  The axial center 36 of the third portion 29c of the relief passage 29 is inclined slightly downward so as to form an obtuse angle θ1 with the axial center 35 of the cylindrical portion 30 (or the relief valve 31). For this reason, compared with the case where the 3rd part 29c is orthogonal to the axis line of the cylinder part 30, oil flows into the 3rd part 29c smoothly.

As clearly shown in FIG. 5D, the third portion 29 c of the relief passage 29 opens toward the inner surface of the pump housing portion 12 constituting the suction passage 19. Accordingly, the relief oil ejected from the third portion 29 c hits the oil contact surface 37 that is a part of the inner surface of the suction passage 19, but the first center as the shaft center 36 of the third portion 29 c approaches the oil contact surface 37. By inclining with respect to the normal 38 of the oil contact surface 37 so as to be separated from the portion 29a , the lower side (first portion 29a) formed by the axis 36 of the third portion 29c and the oil contact surface 37 in a side view . The angle θ2 on the opposite side is set to an obtuse angle.

In the present embodiment, the oil abutment surface 37 is away from The further down (increasing distance from the starting end 29a of the relief passage 29) (the mating surface 39 of the or the pump housing 12 and pump cover 13) the pump cover 13 Inclined .

  In the above configuration, when the discharge pressure of the oil pump 18 becomes excessive, the relief valve 31 is pushed by the oil and moves backward, and the oil is ejected from the third portion 29c of the relief passage 29 to the suction passage 19, but the third portion The oil ejected from 29c does not collide with the oil contact surface 37 of the suction passage 19 from the front, but is guided by the oil contact surface 37 so as to be warped downward, and smoothly changes its direction. To be absorbed. For this reason, the dynamic pressure of the oil does not act as an impact on the inner surface of the suction passage 19, and vibration and noise and sealability deterioration due to this can be prevented.

As in the present embodiment, when the axis (axis) 35 of the third portion 29c is inclined with respect to the axis 35 of the cylindrical portion 30 (or the second portion 29b), the flow of the relief oil can be smoothed. It is effective for suppressing vibration. Further, when the inclined with respect to the third axial center 35 of the portion 29c mating surface 39 as in this embodiment, since the inclination angle with respect to the Align surface 39 can small camphor Rukoto, need to change large design There are no advantages.

  Further, when the axis 35 of the third portion 29c is inclined with respect to the mating surface 39 and the oil contact surface 37 is also inclined with respect to the mating surface 39 as in the present embodiment, the axis of the third portion 29c is Since the angle θ2 formed by the core 35 and the oil contact surface 37 can be made as large as possible, there is an advantage that the oil guide function can be enhanced and vibration can be prevented more effectively. If the portion below the oil contact surface 37 in the suction passage 19 is formed in an arc shape in a side view, the oil guide function can be further improved.

  The present invention can be embodied in various ways other than the above-described embodiment. For example, the relief valve is not limited to the rod type, and for example, a needle type or a rotating plate type can also be adopted. It is also possible to use a ball as the valve body.

  The present invention is actually applicable to an oil pump. Therefore, it can be used industrially.

DESCRIPTION OF SYMBOLS 1 Cylinder block 5 Chain cover 8 Crankshaft 12 Pump housing part which comprises an oil pump 13 Pump cover 15 Pump chamber 16 Inner rotor 17 Outer rotor 18 Oil pump 19 Intake passage 20 Discharge passage 22 Oil filter 29 Relief passage 29a 1st part 29b 2nd part 29c 3rd part (terminal part)
30 Cylinder 31 Valve body 32 Spring 35 Axle of cylinder 36 Axis of third part 37 Oil contact surface 38 Perpendicular of oil contact surface 39 Matching surface of pump housing part and pump cover

Claims (1)

A cylinder block with a crankshaft protruding from one side surface, a chain cover that is fixed to one side surface of the cylinder block and covers transmission means for a valve mechanism that is driven by the crankshaft, and oil that is driven by the crankshaft With a pump,
The oil pump has a structure in which an inner rotor and an outer rotor that rotate integrally with the crankshaft are sandwiched between a pump housing portion provided in the chain cover and a pump cover that is overlapped and fixed thereto ,
An oil suction passage and a discharge passage are formed on the mating surface of the pump housing portion and the pump cover, and a relief passage for allowing the discharged oil to escape to the suction passage when the oil discharge pressure becomes excessive. the via pump cover so formed as to return to the suction passage, the portion formed in the pump cover of the relief passage, the relief valve for opening and closing the relief passage is arranged movably And
Accordingly, the relief passage has a first portion into which the discharged oil flows, a second portion in which the relief valve moves, and a third portion in communication with the second portion and the suction passage. , the formed part pump housing part of the inner surface of the suction passage, the oil ejected from part 3 content of the relief passage is a structure that is a person barrel oil abutment surface,
Part 3 content of the relief passage is, while being formed closer to the side close to the first part portion of the relief passage of the suction passage,
The oil abutment surface, relative to the pump housing portion and the mating surface of the pump cover is inclined away from said mating face with increasing distance from the first part portion of the relief passage,
And, the axis of the third portion of the relief passage is inclined with respect to the oil contact surface so as to move away from the first portion of the relief passage as the oil contact surface is approached.
Internal combustion engine.

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