JP7160505B2 - internal combustion engine - Google Patents

Description

The present invention relates to an internal combustion engine equipped with a hydraulic VVT device (variable valve timing device).

2. Description of the Related Art In an internal combustion engine for a vehicle or the like, the opening/closing timing (valve timing ) of one or both of an intake valve and an exhaust valve is controlled. As a control device for this valve timing, the camshaft is advanced or retarded with respect to the chain sprocket. A hydraulic VVT device controlled by

A hydraulic VVT device is controlled by an oil control valve (OCV). By supplying oil pressure-fed by an oil pump to the OCV, the OCV can be used to switch the destination of the oil and adjust the amount of oil to be sent. , which controls the advance/delay angle of the cam.

Regarding the relationship between the camshaft and the VVT device, an oil passage is provided in the camshaft to allow the rotation of the VVT device while supplying oil. It is necessary to form an oil passage between

Regarding this point, Patent Document 1 discloses a configuration in which a horizontal hole is made in the front part of the longitudinal side of the cylinder head and an OCV is fitted in the horizontal hole, and an oil passage from the OCV to the camshaft is formed on the upper surface of the cylinder head. It is disclosed to consist of a formed groove and a drilled hole communicating with the groove.

Japanese Patent No. 3498821

Although the groove serving as the control oil passage is sometimes formed on the lower surface of the front cam cap , whether it is formed in the cylinder head or in the front cam cap , the groove is not visible in plan view (or bottom view). ), often resulting in a curved shape.

On the other hand, the facing surfaces of the front bearing portion and the front cam cap are semicircular and form a perfect circle as a whole. After setting the front cam cap to a small diameter, the bearing hole formed by both is dredged by cutting with a drill or milling machine to finish it to a predetermined size while the front cam cap is fixed to the cylinder head. .

Chips are generated during this cutting process, and the generated chips enter the grooves for the control oil passages, and clog the bent portions in particular.

In other words, since the cylinder head and front cam cap are made of aluminum, the shavings tend to be in the form of thin strips (chips), so they are pushed into the grooves in an elastically deformed state. Due to the force, the shavings may be stretched in the groove, and therefore, the shavings cannot be removed by simply injecting compressed air.

In this case, tools are used to manually remove it, but not only does the removal work cost a considerable amount, it is left unremoved and may enter the OCV or VVT device. It sometimes caused malfunction. In general, since the groove is formed by casting, the inner surface of the groove often has a casting surface consisting of fine irregularities, so clogging with shavings is likely to occur.

SUMMARY OF THE INVENTION The present invention has been made in view of such a situation, and it is an object of the present invention to form a control oil passage that can prevent clogging of chips caused by cutting.

The internal combustion engine of the present invention is
"A camshaft that can rotate relative to the chain sprocket by a hydraulic VVT device is rotatably held by a plurality of bearings of the cylinder head via a cam cap, and an oil control valve (OCV) that controls the VVT device. ) is attached to the outside of a front bearing portion that rotatably supports the camshaft at a front portion of the cylinder head near the chain sprocket,
In addition, a control oil passage for controlling a VVT device is provided in the front portion of the cylinder head so that one end communicates with the oil control valve and the other end opens to the inner peripheral surface of the front bearing portion. are formed by
This is the basic configuration.

And, in addition to the basic configuration and the first feature , the present invention ,
"The control oil passage and the oil passage boss portion are inclined so as to be lowered from the front bearing portion toward the oil control valve. A counter rib is formed in a symmetrical posture with the oil passage boss.”
It also has a second feature.

In the present invention, the control oil passage from the OCV to the camshaft is a hole facing the OCV from the inner peripheral surface of the front bearing portion. Therefore, when finishing the inner peripheral surface of the intake front bearing portion and the front cam cap with the front cam cap fixed, even if chips enter the control oil passage, it can be easily removed by injecting compressed air or the like. can be removed completely.

In particular, when the control oil passage is formed by drilling, the inner surface of the control oil passage becomes much smoother than the casting surface. , can be easily pushed out by a jet of compressed air.

Therefore, according to the present invention, it is possible to reduce the time and effort required for processing, contribute to cost reduction, prevent clogging with chips, and improve the accuracy of the VVT device and the operation of the VVT device.

When a VVT device is provided, the front portion of the front bearing portion may be projected forward from the front wall portion of the cylinder head. By providing the passage boss portion, the oil passage can be formed as far forward as possible. Therefore, it is easy to match the dimensions with the VVT device and the OCV, and the freedom of design is high.

Cylinder heads are generally made of cast aluminum. The first feature is that the oil passage boss protrudes forward, which increases the space in which the molten metal flows during casting. As a result, it can contribute to the improvement of casting quality. In addition, since the boss portion protrudes from the front surface of the cylinder head in the form of a rib, there is an advantage that the rigidity of the cylinder head can be improved due to the reinforcing effect.

Furthermore, in the second feature, since the control oil passage is inclined so as to be lowered from the front bearing toward the OCV, communication can be ensured even if there is an oil port on the outer circumference of the OCV. Therefore, it is excellent in reality adaptability.

In addition, although the oil passage boss has a reinforcing effect as described above, if the present invention is adopted, the auxiliary boss is formed symmetrically with the oil passage boss, so the rigidity of the portion surrounding the front bearing is increased. can be made uniform to prevent distortion when external force or thermal stress is applied to the cylinder head. Therefore, it is possible to maintain the roundness of the front bearing portion at a high level and ensure smooth rotation of the camshaft. Thereby, a mechanical loss can be suppressed.

1 is a perspective view of a cylinder head according to an embodiment, viewed from the front and lower side; FIG. It is the perspective view seen from the front upper part. (A) is a perspective view of the main part as seen from the rear upper side, and (B) is a perspective view of the main part as seen from the laterally lower side. It is a front view (front view) of a cylinder head. FIG. 5 is a plan view partially displayed as a cross-sectional view taken along line V-V of FIG. 4; (A) is a sectional view taken along line VIA-VIA in FIG. 5, and (B) is a bottom view of the cam cap. FIG. 4 is a perspective view cut along a plane including the centerline of the OCV mounting hole; (A) is a cross-sectional view taken along line VIIIA-VIIIA in FIG. 6A, and (B) is a cross-sectional view taken along line VIIIB-VIIIB in FIG. 6A. (A) is an IXA-IXA horizontal sectional view of FIG. 3(B), and (B) is an IXB-IXB horizontal sectional view of FIG. 6(A). 1 is a partial front view (front view) of an internal combustion engine; FIG.

(1). Overview Next, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the terms front-rear and left-right are used to specify the direction, but the front-rear direction is the direction of the crankshaft, and the portion where the front cover (or the chain sprocket 30 and timing chain 31 shown in FIG. 10) is arranged. is before. Just to make sure, the directions are clearly shown in FIGS.

The basic structure of the cylinder head 1 is the same as that of the conventional cylinder head 1. For example, as shown in FIG. It has a box-like shape with an open top. The front wall portion 2 is formed with an intake front bearing portion 5 and an exhaust front bearing portion 6 . Reference numeral 4a shown in FIG. 2 is an exhaust outlet.

Both the front bearings 5 and 6 protrude forward from the front wall 2, but the intake front bearing 5 protrudes to a greater extent. Bosses, ribs, member mounting holes, and the like are formed on the front surface of the front wall portion 2 .

Inside the cylinder head 1, a plurality of pairs of intake intermediate bearing portions 7 and exhaust intermediate bearing portions 8 extending in the left-right direction are formed so as to be spaced apart in the cam shaft direction. A plug boss portion 9 into which an ignition device is fitted is formed between the intake intermediate bearing portion 7 and the exhaust intermediate bearing portion 8 .

As shown in FIG. 3(B), a plurality of intake ports 10 are formed side by side in the front-rear direction on the intake side surface of the cylinder head 1 . In this embodiment, the intake camshaft 11 is provided with a VVT device (not shown). An OCV mounting hole 12 is formed in the upper portion, and a hydraulic OCV (Oil Control Valve) 13 is fitted in the OCV mounting hole 12 as shown in FIG. 3(A).

As shown in FIG. 10 , a chain sprocket 30 is attached to the intake and exhaust camshafts via the rotor of the VVT device, and a timing chain 31 is wound around both chain sprockets 30 . The timing chain 31 is held narrowed by an intake-side chain guide 32 and an exhaust-side chain guide 33 so that the interval between the outward and return paths is narrowed.

The exhaust-side chain guide 33 is fixed, while the intake-side chain guide 32 is movable to adjust the tension of the timing chain 31 . Fixed.

(2) Control structure of OCV As shown in FIG. 17 and a retarding annular groove 16b (see FIG. 5) communicating therewith are formed. A retard control oil passage 19 connecting the grooves 16b has one end (upstream end) communicating with the OCV mounting hole 12 and the other end (downstream end) opening to the inner peripheral surface of the intake front bearing portion 5. is formed as

As can be understood from FIGS. 4, 5, and 9(B), the advance control oil passage 18 and the retard control oil passage 19 are arranged forward and backward with the advance control oil passage 18 positioned in front. in line. Also, the advance control oil passage 18 is high and the retard control oil passage 19 is low. These advance control oil passage 18 and retard control oil passage 19 are formed as straight holes by drilling (it can also be formed by casting).

Needless to say, the other end 18b of the advance control oil passage 18 communicates with the advance annular groove 16a of the intake camshaft 11, and the other end 19b of the retard control oil passage 19 is It communicates with the retarding annular groove 16b of the intake camshaft 11 . As clearly shown in FIGS. 4 and 6A, the OCV 13 is positioned below the intake front bearing 5, so the control oil passages 18, 19 are low at one ends 18a, 19a and 18b at the other end 18b . , 19b are inclined upward.

As shown in FIGS. 5 and 9, one end 18a of the advance control oil passage 18 and one end 19a of the retard control oil passage 19 are open to the inner peripheral surface in front of the OCV mounting hole 12. One end 19a of the retard control oil passage 19 is located on the far side. Further, one end 18a of the advance control oil passage 18 is positioned slightly higher than one end 19a of the retard control oil passage 19. As shown in FIG. In FIGS. 4 and 9, one ends 18a and 19a of the oil passages should originally be drawn with dotted lines, but are blacked out for clarity.

The advance angle control oil passage 18 and the advance angle control oil passage 18 are inclined so as to become lower with distance from the intake front bearing portion 5 in a front view, and are inclined from the intake front bearing 5 in a plan view. 5 and 9, due to the relationship between the front and rear positions, the left and right positions, and the height of the ends 18a, 19a and the other ends 18b, 19b. It has a posture that intersects in a substantially V shape both in view and plan view.

As shown in FIG. 6A, the intake camshaft 11 is rotatably held by the intake front bearing 5 by the intake front cam cap 21 . As shown in FIG. 6(B), an annular groove 22 is formed in the inner peripheral surface of the intake front cam cap 21. This groove is for lubrication.

As described above, the intake front bearing portion 5 protrudes greatly forward of the front wall portion 2 . For this reason, as can be understood from FIG. Close proximity. Therefore, as shown in FIGS. 1, 2 and 4, on the front surface of the front wall portion 2, an advance oil passage boss portion 23 corresponding to the advance control oil passage 18 and a retard control oil passage 19 are provided. The retarded oil passage boss portion 24 is formed in an inclined posture. The oil passage bosses 23 and 24 are exposed in a forward-facing recess 2 a formed in the front wall portion 2 .

Since the advance control oil passage 18 partially protrudes in front of the front wall portion 2, the advance oil passage boss portion 23 protrudes greatly from the front surface of the front wall portion 2. Since the passage 19 hardly protrudes, the projection dimension of the retard oil passage boss portion 24 is small. As for the height position, the retard angle control oil passage 18 is high and the retard angle control oil passage 19 is low. is lower than If both oil passages 18 and 19 are at the same height, only one boss portion is required.

As shown in FIGS. 1, 2, 4 and 6(A), of the front surface of the front wall portion 2, the opposite side (right side) of the oil passage boss portions 23 and 24 across the axial center of the intake front bearing portion 5 ), a counter rib 25 inclined symmetrically with the oil passage boss portions 23 and 24 projects forward. The counter rib 25 is connected to the intake front bearing portion 5, and the oil passage boss portions 23, 24 and the counter rib 25 are roughly in a V-shaped posture when viewed from the front.

The OCV 13 needs to supply and drain oil. This point will be explained below. As shown in FIG. 9A, the oil supply hole is composed of a horizontal hole 26a extending in the direction of the cam axis and a vertical hole 26b extending vertically. That is, the horizontal hole 26a is formed below the OCV mounting hole 12, and the vertical hole 26b is formed so as to communicate with the horizontal hole 26a and the OCV mounting hole 12 there.

As shown in FIGS. 2 and 4, an oil reservoir 26c is formed in the front surface of the cylinder head 1 obliquely below the horizontal hole 26a. Oil is supplied via a branch passage 26d (see FIG. 4) and a longitudinal hole.

The oil pool 26c is blocked by a chain guide tensioner 34 shown in FIG. It communicates with the hole 26a. By using the chain guide tensioner 34 as part of the oil passage in this way, the structure can be simplified, which contributes to cost reduction and weight reduction. The communication hole 26e may be formed inside the tensioner 34, or may be formed in one or both of the mating surfaces of the cylinder head 1 and the tensioner 34. As shown in FIG.

In the OCV 13, when oil is supplied to the advance control oil passage 18, the oil in the retard working chamber is discharged, and when oil is supplied to the retard control oil passage 19, the oil is supplied to the advance control oil passage. The oil in the working chamber is discharged. Therefore, two front and rear drain holes are provided, and the front drain hole communicates with the first drain hole 27 formed at the bottom of the OCV mounting hole 12, as shown in FIG. 9(A). .

The first drain hole 27 is elongated in the cam axis direction and opens in the front surface of the cylinder head 1 . The first drain hole 27 remains open from the front, and the oil flows down into the chain chamber. Therefore, the timing chain 31 can be lubricated.

As shown in FIGS. 7 and 9A, a discharge hole 13a provided in the rear portion of the OCV 13 opens into a space 1a formed in the cylinder head 1. As shown in FIG. The oil that has flowed down into the space 1a returns to the oil pan through an oil drop hole (not shown). In FIGS. 7 and 9A, the rear discharge hole 13a is shown facing downward, but it may be opened rearward and flow down from a lateral hole formed in the OCV mounting hole 12 to the space 1a.

(3) Summary Since the control oil passages 18 and 19 are formed as straight holes in the cylinder head 1, simple drilling is sufficient when they are formed by cutting. Therefore, in the process of finishing the bearing hole formed by the intake front cam cap 21 and the intake front bearing portion 5 in a state where the intake front cam cap 21 is fixed, the control oil passages 19, 19 are filled with shavings . If it gets in, it can be easily removed with a jet of compressed air.

That is, since the control oil passages 18 and 19 are straight and the inner surfaces are smoothed by drilling, even if chip-like chips enter in an elastically deformed state or lump-like state, the chips can be controlled. It is in a state where it is difficult to get caught on the inner surfaces of the oil passages 18 and 19 (a state in which friction is small), so it can be easily removed by a pressure equivalent to the injection of compressed air.

Therefore, it is possible to reduce the time and effort required for processing, and prevent malfunction of the OCV 13 and the VVT device due to clogging of chips. After finishing the bearing hole, the front cam cap 21 is removed and both are washed with washing oil, and then the remaining chips are removed by injecting compressed air (in some cases, washing A deburring process may be provided before.).

Further, since the boss portions 23 and 24 are provided on the front surface of the cylinder head 1, the control oil passages 18 and 19 protrude from the front of the front wall portion 2 or are close to the front surface of the front wall portion 2. However, the control oil passages 18 and 19 can be formed without any trouble. Therefore, it is not necessary to change the design of the cylinder head 1 or the position of the OCV 13, and the freedom of design is high.

Although the cylinder head 1 is an aluminum casting, the bosses 23 and 24 enlarge the cavity of the mold, so that the molten metal flows well in the mold and contributes to the improvement of casting quality.

Furthermore, since the boss portions 23 and 24 protrude from the front surface of the cylinder head 1, the rigidity of the cylinder head 1 can be improved by the rib effect. In this case, since the counter ribs 25 are provided symmetrically with the boss portions 23 and 24, the rigidity of the intake front bearing portion 5 and its peripheral portion is made uniform. Therefore, when the timing chain is subjected to mechanical external force or thermal expansion due to the rotation of the timing chain, the intake camshaft 11 can be prevented from being distorted and smoothly rotated.

As shown in FIG. 5, in the present embodiment, the control oil passages 18 and 19 are inclined so as to be shifted rearward from the intake front bearing portion 5 toward the OCV 13 in plan view. Therefore, the OCV 13 can be arranged behind the front surface of the cylinder head 1 while allowing the intake front bearing 5 to protrude forward. Therefore, it is not necessary to provide the cylinder head 1 with a forward-facing boss portion for arranging the OCV 13 . Therefore, the increase in size and weight of the cylinder head 1 can be prevented.

Further, in this embodiment, the control oil passages 18 and 19 are opened to the inner peripheral surface of the intake front bearing portion 5 at different heights. By changing the height, you can increase the distance without increasing the distance in the front-to-back direction. Therefore, it is possible to prevent a decrease in strength due to the provision of the two control oil passages 18 and 19 .

The present invention can also be applied to an exhaust camshaft.

The present invention can be embodied in an internal combustion engine with a VVT device. Therefore, it can be used industrially.

Reference Signs List 1 cylinder head 2 front wall portion 3, 4 side wall portion 5 intake front bearing portion 11 intake camshaft 12 OCV mounting hole 13 OCV (oil control valve)
Reference Signs List 15 advance longitudinal passage 16a advance annular groove 16b retard annular groove 18 advance control oil passage 19 retard control oil passage 21 intake front cam cap 23 advance oil passage boss 24 retard oil Road boss 25 Counter rib 26 Oil supply hole 27 Oil drain hole (drain hole)

Claims (1)

A camshaft rotatable relative to the chain sprocket by a hydraulic VVT device is rotatably held by a plurality of bearing portions of the cylinder head via a cam cap, and an oil control valve for controlling the VVT device mounted outside a front bearing portion that rotatably supports the camshaft at a front portion of the cylinder head near the chain sprocket,
In addition, a control oil passage for controlling a VVT device is provided in the front portion of the cylinder head so that one end communicates with the oil control valve and the other end opens to the inner peripheral surface of the front bearing portion. An internal combustion engine formed by
The front bearing portion protrudes forward from a front wall portion of the cylinder head, and an oil passage boss for forming the control oil passage on the front surface of the cylinder head and below the front bearing portion. The part protrudes forward,
In addition, the control oil passage and the oil passage boss portion are inclined so as to be lowered from the front bearing portion toward the oil control valve. A counter rib is formed that is symmetrical with the oil passage boss.
internal combustion engine.

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