JP2020122417A - Internal combustion engine - Google Patents

Abstract

To provide a structure which is simple, and excellent in safety, related to the lubrication structure between a crank sprocket and a timing chain.SOLUTION: An oil injection port 17 for injecting oil toward an end face 12a of a crank sprocket 12 is formed at an engine main body such as a cylinder block 3. The oil injection port 17 communicates with a back face groove 15 formed at a bearing part 4. The oil injection port 17 is arranged in a region at this side rather than an engagement start part 19 of the crank sprocket 12 and a timing chain 11 when viewed from a rotation direction 18 of the crank sprocket 12. The oil flows along teeth 12b from the rear end face 12a of the crank sprocket 12, and is transited to the timing chain 11. It is preferable to form an annular guide groove 20 at the crank sprocket 12.SELECTED DRAWING: Figure 1

Description

The present invention relates to an internal combustion engine, and is characterized by a lubricating structure of a meshing portion between a crank sprocket and a timing chain.

The meshing portion between the crank sprocket and the timing chain needs to be lubricated with oil. As this lubrication structure, Patent Documents 1 and 2 disclose that a nozzle (oil jet) for ejecting oil is provided in a portion of a cylinder block higher than a crank sprocket.

Of these, in Patent Document 1, the oil jetted downward from the nozzle is set so that the crank sprocket directly hits the meshing start portion with the timing chain, while in Patent Document 2, the oil is front cover (chain cover). ), it hits the projection diagonally from above and after it reflects, it pours down to the meshing start portion of the crank sprocket and the timing chain.

JP, 2004-353551, A Micro film of Jitsukaihei 3-454071

In Patent Documents 1 and 2, since a dedicated nozzle must be attached to the cylinder block, there is a problem that the structure is complicated and cost is increased, or the nozzle falls off due to vibration or the like and is caught between the crank sprocket and the timing chain. , There is a problem of leading to a serious accident.

Further, the oil pressure changes depending on the engine speed, but in Patent Documents 1 and 2, since the nozzle is far from the crank sprocket, the engine speed is low and the oil viscosity is high during warm-up operation. If the pressure of the oil is low (the flow velocity is slow), the oil may not reach the target area and may cause poor lubrication.

The present invention has been made to improve the present situation.

The present invention is
``Having an engine body including a cylinder block, a crank shaft rotatably held by the cylinder block, and a crank sprocket fixed to the crank shaft and meshing with a timing chain,
An oil ejection port communicating with an oil passage formed inside the engine body is provided at one end surface of the crank sprocket at any one of the front and rear portions of the engine body sandwiching the crank sprocket when viewed from the crank axis direction. It is open towards"
That is the basic configuration.

And in addition to this basic configuration,
“The oil ejection port is opened to one end surface of the crank sprocket at a position closer to a front side than a meshing start portion of the crank sprocket and the timing chain when viewed from the rotation direction of the sprocket.”
Is added.

In the present invention, the oil ejection port may be formed in the cylinder block, or may be provided in the front cover (chain cover, chain case) which covers the timing chain and constitutes the engine body.

When the oil ejection port is formed in the cylinder block, the oil ejection port opens forward, and when the oil ejection port is formed in the front cover, the oil ejection port opens rearward.

In the present invention, it is preferable to provide the crank sprocket with oil guide means for guiding the oil ejected from the oil ejection port and attached to the teeth toward the teeth. The oil guide means may be, for example, an annular groove or an annular rib (both of which can be used together).

In the present invention, the oil ejected from the oil ejection port is scattered in the radial direction by the centrifugal force after hitting one end surface of the crank sprocket, and while being wet to the teeth of the crank sprocket and the timing chain, it is also transferred to the timing chain. .. Therefore, the meshing portion between the crank sprocket and the timing chain is lubricated.

Further, in the present invention, since the nozzle is not required, the structure is simple and the cost can be suppressed, and there is no accident due to the detachment of the nozzle, which is excellent in safety. Further, since the oil ejection port and the crank sprocket are close to each other, the oil can be surely ejected to the crank sprocket even if the engine speed is low, so that the oil does not reach the target portion. No trouble will occur.

As described above, it is preferable to provide the oil guide means on one end surface of the crank sprocket so that the lubricating effect of the meshing portion between the crank sprocket and the timing chain can be ensured.

FIG. 2A is a vertical sectional side view of the first embodiment and is a sectional view taken along line I-I of FIG. 2B, and FIG. 2B is an enlarged view of a portion of an annular bearing groove. 1A is a sectional view taken along line IIA-IIA in FIG. 1, and FIG. 1B is a sectional view taken along line IIB-IIB in FIG. It is a figure which shows 2nd Embodiment, (A) is a vertical side view, (B) is BB sectional drawing of (A). (A) is a figure which shows 3rd Embodiment, (B) is a figure which shows 4th Embodiment. (A) is a figure which shows 5th Embodiment, (B) is a figure which shows 6th Embodiment.

Next, an embodiment of the present invention will be described with reference to the drawings. In the present application, the front and rear words are used to specify the direction, but the front and rear direction is the crank axis direction, and the side on which the crank pulley is arranged is the front and the side on which the mission is arranged is the rear. As a precaution, the direction is clearly shown in FIG.

(1). First Embodiment/Basic Structure First, a first embodiment shown in FIGS. 1 and 2 will be described. FIG. 1(A) shows the front part of the engine, and the front journal 2 formed in the front part of the crankshaft 1 is mounted on the bearing part 4 of the cylinder block 3 in a pair of upper and lower bearing metals 5, 6 and a crank cap. It is rotatably held via 7. The bearing metals 5 and 6 are held by the cylinder block 3 so as not to be displaced, and form a part of the engine body described in the claims.

Needless to say, the crankshaft 1 has a rear journal and an intermediate journal, and adjacent journals are linked by a pair of crank arms 9 linked by crankpins 8.

A sprocket fixing part 10 having a diameter slightly smaller than that of the front journal 2 is continuous to the front end of the front journal 2 on the crankshaft 1. The crank sprocket 12 with which the timing chain 11 meshes is fixed to the sprocket fixing part 10. There is. The crank sprocket 12 is held by the key 13 so as not to rotate relative to the sprocket fixing portion 10.

Although illustration is omitted, a front cover that surrounds the timing chain 11 is fixed to the front surface of the cylinder block 3, and the front end portion of the crankshaft 1 is exposed in front of the front cover. A crank pulley for driving the auxiliary machine is fixed. The front cover also constitutes the engine body.

The front cover is integrally formed with the pump housing of the trochoidal oil pump.The pump chamber is formed by fixing the pump cover to the pump housing from the rear side, and the inner rotor that meshes with the pump chamber is formed in the pump chamber. And an outer rotor are arranged. The inner rotor is fixed to the front part of the crankshaft 1.

An oil supply passage through which oil pressurized in the pump chamber flows is formed in the front cover, and a downstream end of the oil supply passage communicates with a main gallery formed in the cylinder block 3. Then, the oil pressure-fed to the main gallery is fed to each lubrication unit and the like via the branch gallery.

As described above, the front journal 2 is rotatably held via the bearing metals 5 and 6, and the sliding surface between the bearing metals 5 and 6 and the front journal 2 has a vertical longitudinal direction formed on the cylinder block 3. It is lubricated by the oil sent from the branch gallery 14.

That is, the back surface groove 15 extending in the circumferential direction is formed on at least the inner peripheral surface of the bearing portion 4 among the inner peripheral surface of the bearing portion 4 and the inner peripheral surface of the crank cap 7. The lower end of the gallery 14 communicates. The upper end of the branch gallery 14 communicates with a main gallery (not shown).

An annular lubricating groove 15a is formed on at least the inner peripheral surface of the upper bearing metal 5. As shown in FIG. 1B, the annular lubricating groove 15a has a trapezoidal cross-sectional shape that widens toward the front journal, and the optimum position of the annular lubricating groove 15a (the oil film thickness of the bearing surface is the maximum surface pressure portion). (A position formed in a wedge shape toward the rear surface) and the rear surface groove 15 are communicated with each other through the communication hole 15b, so that an appropriate oil film of oil is formed and a sliding surface between the bearing metal 5, 6 and the front journal 2. Is lubricated. That is, since the back surface groove 15 is formed in the bearing portion 4, the opening position of the branch gallery 14 and the position of the communication hole 16 do not necessarily have to match, and the degree of freedom in design increases.

(2). Lubricating structure of crank sprocket Then, as a lubricating means for the meshing portion of the crank sprocket 12 and the timing chain 11, the bearing 4 is communicated with the rear surface groove 15 toward the rear end surface 12a of the crank sprocket 12. An oil ejection port 17 for ejecting oil is formed. Therefore, in the present embodiment, the rear end surface 12a of the crank sprocket 12 is the one end surface described in the claims.

In FIG. 2, the position of the oil ejection port 17 is indicated by a black circle. As shown in this figure, the oil ejection port 17 is located at a position slightly before the meshing start portion A between the crank sprocket 12 and the timing chain 11 when viewed from the rotation direction 18 of the crankshaft 1.

As described above, the oil ejection port 17 communicates with the back surface groove 15 formed in the bearing portion 4 into which the upper bearing metal 5 is fitted. Therefore, in this embodiment, the back surface groove 15 also serves as the oil passage described in the claims.

An annular guide groove 20 having a semicircular cross section is formed as an example of an oil guide means for flowing the oil ejected from the oil ejection port 17 in a radial direction at a position on the rear end surface 12a of the crank sprocket 12 that faces the oil ejection port 17. doing. Although the outer peripheral portion of the crank sprocket 12 is composed of a large number of teeth 12b, the annular guide groove 20 is designed so as not to interfere with the group of teeth 12b.

With the above configuration, when the engine is started, the oil is jetted toward the annular guide groove 20 of the crank sprocket 12 with a slight time lag. Then, the oil attached to the annular guide groove 20 is directed in the rotation direction of the crank sprocket 12 while flowing along the outer peripheral direction by the centrifugal force.

Therefore, as shown by the dotted line arrow in FIG. 2B, the oil falls between the crank sprocket 12 and the timing chain 11 in a posture in which the oil falls toward the rotation direction 18 of the crank sprocket 12 with respect to the radiation passing through the axis. The crank sprocket 12 flows or is skipped toward the meshing start portion 19.

When the oil reaches or reaches the meshing start portion 19 through the rear end surface 12a of the crank sprocket 12, the oil is transferred to the link plate or pin on the rear side of the timing chain 11, and the front side through the pin. It will also be transferred to the side link plate.

In addition, a part of the oil attached to the annular guide groove 20 wraps around the inner surface of the tooth 12b of the crank sprocket 12 before reaching the meshing start portion 19, whereby the oil that reaches the pin forming the timing chain 11 is released. Oil transfer is also performed. As shown in FIG. 1, the tooth 12b has a trapezoidal shape in which the width becomes narrower as it moves away from the axis, and the front and rear end surfaces are inclined, so that the oil easily goes around the inner surface of the tooth 12b.

In this way, the oil ejected toward the rear end surface 12a of the crank sprocket 12 is transferred to the teeth 12b of the crank sprocket 12 and the link plate and pin of the timing chain 11 as the crank sprocket 12 rotates, Lubrication of the meshing portion between the crank sprocket 12 and the timing chain 11 and lubrication between the link plate and the pin forming the timing chain 11 are performed.

When the annular guide groove 20 is formed as in the embodiment, since the annular guide groove 20 functions as an oil reservoir, there is an advantage that the oil can be efficiently guided toward the meshing start portion 19.

Further, the oil jetting means has a simple structure in which the oil jetting port 17 is provided in the upper bearing metal 5, so that the cost can be largely suppressed. Further, since the oil ejection port 17 is close to the crank sprocket 12, the oil can be surely ejected even when the engine is rotating at a low speed, so that the lubrication can be accurately performed over the entire rotation range.

(2). Other Embodiments Next, other embodiments shown in FIG. In the second embodiment shown in FIG. 3, the oil ejection port 17 is formed as a groove on the inner peripheral surface of the bearing portion 4.

It can be said that the annular guide groove 20 of the crank sprocket 12 is preferably formed close to the group of the teeth 12b, but the position of the oil ejection port 17 is dependent on the thickness of the bearing metals 5 and 6 and the outer diameter of the crank sprocket 12. Therefore, as a dimensional conflict, it can be formed as a hole in the bearing portion 4 as in the first embodiment or as a groove in the inner peripheral surface of the bearing portion 4 as in the second embodiment.

4 and 5 show an example of development of the oil guide means. Among them, in the third embodiment shown in FIG. 4A, the annular guide groove 20 is formed with a group of the radial grooves 22 which are opened in the valley portion between the adjacent teeth 12b. Therefore, a large number of the radial grooves 22 are formed outside the annular guide groove 20. In this embodiment, the oil easily propagates to the inner surfaces of the teeth 12b, so that the lubricating effect can be greatly improved.

In the fourth embodiment shown in FIG. 4(B), the crank sprocket 12 is formed with a group of guide holes 23 that are open to the annular guide groove 20 and each valley. In this example, the oil can be sent to the front-rear intermediate part of the valley between the teeth 12b and the teeth 12b, so that the oil can be sent to the inner surface of the teeth 12b even better and a higher lubrication effect can be enjoyed. In addition, in this embodiment, strength reduction can also be suppressed.

In FIG. 5, ribs are formed on the rear end surface 12a of the crank sprocket 12 as the oil guide means. Of these, in the fifth embodiment shown in FIG. 5(A), a single annular guide rib 24 is formed on the rear end surface 12a of the crank sprocket 12. On the other hand, in the sixth embodiment shown in FIG. 5B, a group of independent guide ribs 25 is formed on the rear end surface 12a of the crank sprocket 12. In any case, the ribs 24 and 25 are formed at positions that do not interfere with the timing chain 11.

In the example of FIG. 5(A), the outer peripheral surface of the annular guide rib 24 is formed as an inclined surface whose outer diameter decreases toward the protruding direction. Therefore, it can be said that the oil easily flows toward the inner surfaces of the teeth 12b. Of course, the annular guide rib 24 may be formed in a simple quadrangle. Alternatively, it is also possible to combine the annular guide groove 20 of the previous embodiment and the annular guide rib 24 of the present embodiment. In this case, it can be said that the lubricating effect is excellent because the function of stopping the oil is high.

The independent guide rib 25 formed in the sixth embodiment of FIG. 5B is inclined with respect to the radiation passing through the axis. That is, the crank sprocket 12 is inclined toward the rotation direction 18 so that the distance from the shaft center becomes smaller. In this embodiment, since the oil ejected from the oil ejection port 17 is efficiently pushed in the radial direction by the independent guide rib 25, it is presumed that a high lubrication effect can be exhibited.

When the ribs 24 and 25 are used as the oil guide means as in the embodiment of FIG. 5, there is an advantage that the strength reduction of the crank sprocket 12 can be prevented.

Although the embodiments of the present invention have been described above, the present invention can be embodied in various other ways. For example, it is possible to provide an oil ejection port on the front cover to eject oil to the front end surface of the crank sprocket. Further, the oil ejection port 17 can be communicated with the branch gallery.

The present invention can be embodied in a lubrication structure for a crank sprocket and a timing chain. Therefore, it can be used industrially.

1 crankshaft 2 front journal 3 cylinder block 4 bearing part 5,6 bearing metal 7 crank cap 10 sprocket fixing part 11 timing chain 12 crank sprocket 12a rear end face (one end face)
12b teeth 14 branch gallery 15 back surface groove 15a annular lubricating groove 17 oil jet 18 rotation direction of crank sprocket 19 meshing start portion 20 annular guide groove as an example of oil guide means

Claims (1)

It has an engine body including a cylinder block, a crank shaft rotatably held by the cylinder block, and a crank sprocket that is fixed to the crank shaft and meshes with a timing chain.
An oil ejection port communicating with an oil passage formed inside the engine body is provided at one end face of the crank sprocket at any one of the front and rear portions of the engine body when sandwiching the crank sprocket when viewed from the crank axis direction. It has a structure that opens toward
The oil jet port is opened at one end surface of the crank sprocket at a position closer to the front side than the meshing start portion between the crank sprocket and the timing chain when viewed from the rotation direction of the sprocket.
Internal combustion engine.

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