WO2024095432A1

WO2024095432A1 - Cylinder head structure of internal combustion engine

Info

Publication number: WO2024095432A1
Application number: PCT/JP2022/041104
Authority: WO
Inventors: 龍太吉田; 敦朗小峠; 広直禰津; 和貴有馬
Original assignee: 日産自動車株式会社
Priority date: 2022-11-04
Filing date: 2022-11-04
Publication date: 2024-05-10

Abstract

Air-intake-side and air-discharge-side hydraulic lash adjusters (36, 37) are provided to a cylinder head (1) in an internal combustion engine. An oil original-pressure passage (45) is positioned at a width-direction central section of the cylinder head (1), the oil original-pressure passage (45) communicating with an oil reservoir part (46). A cam carrier internal passage (52) that passes through the interior of a cam carrier (2) is provided to the air-intake-side lash adjuster (36). Oil is supplied from the oil reservoir part (46) to a lash-adjuster mounting hole (38) via the cam carrier internal passage (52) and an air-intake-side oil passage (53).

Description

Cylinder head structure for internal combustion engine

This invention relates to a cylinder head structure for an internal combustion engine equipped with a hydraulic lash adjuster, and in particular to an improvement in the layout of the oil passages that supply oil to the lash adjuster.

Hydraulic lash adjusters are known to automatically adjust valve clearance to zero in the valve mechanisms of intake and exhaust valves in internal combustion engines. In configurations where this hydraulic lash adjuster is provided in the cylinder head, an oil passage is generally required to guide the oil supplied from the cylinder block to the hydraulic lash adjuster.

Patent Document 1 discloses a configuration in which an oil reservoir covered by a cam cap member is formed between the intake camshaft and exhaust camshaft of the cylinder head, and an oil passage is formed from the bottom of this oil reservoir to a hydraulic lash adjuster.

As disclosed in Patent Document 1, conventionally, the entire oil passage for the hydraulic lash adjuster was formed inside the cylinder head, for example by drilling, which limited design freedom and sometimes made it difficult to position the oil passage due to interference with other components.

Japanese Utility Model Application Publication No. 5-1807

The present invention relates to
A cylinder head;
a first camshaft and a second camshaft, one of which is for an intake valve and the other is for an exhaust valve;
a hydraulic lash adjuster disposed in the cylinder head corresponding to at least the first camshaft;
a cam carrier fixed to an upper portion of the cylinder head and supporting at least a first camshaft;
A cylinder head structure for an internal combustion engine comprising:
When viewed in the cylinder axial direction, an oil source pressure passage is located inside the cylinder head between the first camshaft and the second camshaft,
A portion of the oil passage from this oil source pressure passage to the hydraulic lash adjuster passes through the inside of the cam carrier as the cam carrier internal passage.

Pressurized oil is supplied from the cylinder block to the oil source pressure passage inside the cylinder head, and from there it is sent to the hydraulic lash adjuster via an oil passage. Part of this oil passage passes through the inside of the cam carrier. This means that there are fewer restrictions on the placement of the oil passage due to interference with other parts on the cylinder head side.

The cam carrier is located relatively high up in the internal combustion engine and the vertical distance to the lash adjuster is long, so oil is retained even if the internal combustion engine is left unused for an extended period of time. This ensures that oil is supplied to the lash adjuster from the beginning of the next startup.

FIG. 2 is a front view of a cylinder head equipped with a cam carrier. FIG. FIG. 4 is a cross-sectional view of a cylinder head equipped with a cam carrier. FIG. 4 is an explanatory diagram showing the layout of oil passages. FIG. FIG.

Below, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view showing a cylinder head 1 of an internal combustion engine according to the present invention together with a cam carrier 2. The cylinder head 1 is integrally cast using a metal material, such as an aluminum alloy, and is attached to the upper surface of a cylinder block 3. The internal combustion engine of the embodiment is an in-line three-cylinder spark ignition internal combustion engine, a so-called gasoline engine, and is mounted in a so-called horizontal position at the front of a vehicle. When mounted on the vehicle, the central axis of the cylinder is generally vertical, and therefore FIG. 1 generally corresponds to the position when mounted on the vehicle.

The internal combustion engine of the embodiment has a pent roof type combustion chamber with a spark plug and a fuel injection valve in the center of the combustion chamber, and each cylinder has a pair of intake valves and a pair of exhaust valves.

The cylinder head 1 is equipped with an intake camshaft 5 for the intake valves and an exhaust camshaft 6 for the exhaust valves. The cam carrier 2 is configured as a cover that covers the top opening of the cylinder head 1, and is joined and fixed to the top surface of the cylinder head 1 via an appropriate sealing member such as a liquid gasket. The cam carrier 2 has an intake side camshaft bearing portion 11 and an exhaust side camshaft bearing portion 12 that are roughly semicircular toward the bottom, and rotatably supports the intake camshaft 5 and the exhaust camshaft 6 between them and

cam brackets

13 and 14 that are attached opposite these

camshaft bearing portions

11 and 12.

As shown in FIG. 1, the intake camshaft 5 is positioned at a relatively lower height position along the cylinder center axis compared to the exhaust camshaft 6. Correspondingly, the height position of the upper edge portion of the cam carrier 2 covering the upper part of each

camshaft

5, 6 is also configured so that the intake camshaft 5 side is lower than the exhaust camshaft 6 side. In one embodiment, the internal combustion engine is mounted in the engine room at the front of the vehicle with the intake camshaft 5 side facing the front of the vehicle and the exhaust camshaft 6 side facing the rear of the vehicle. Therefore, the clearance between the vehicle's engine hood (shown by imaginary line L), which is tilted so that the front end is in a low position, is appropriate on both the intake camshaft 5 side and the exhaust camshaft 6 side.

As shown in FIG. 2, the cam carrier 2 in one embodiment has a ladder-like configuration in which two

camshaft housings

21, 22 that extend in the cylinder row direction are connected to each other at positions between the cylinders. At three locations that correspond to cylinder positions in the cylinder row direction, a relatively large injection valve opening 23 is provided between the two

camshaft housings

21, 22. In addition, plug holes 24 for inserting spark plugs are each formed in a cylindrical shape on the exhaust camshaft 6 side (camshaft housing 22 side) of the injection valve opening 23. The cam carrier 2 is cast as a single unit using a metal material, such as an aluminum alloy.

Figure 3 is a cross-sectional view of the cylinder head 1 and cam carrier 2 shown in Figure 1, cut along a cross section passing through the centers of the intake and exhaust valves. As mentioned above, it has a pent roof type combustion chamber 31, to which the intake port 32 and exhaust port 33 are connected. The valve mechanism is not shown in Figure 3, but as is well known to those skilled in the art, cylindrical stem guides are attached to the stem

guide mounting holes

34, 35, respectively, and poppet valve type intake and exhaust valves are assembled together with valve springs.

FIG. 6 is an explanatory diagram showing an outline of the valve mechanism not shown in FIG. 3. A rocker arm 101, one end of which is supported by the hydraulic lash adjuster 36, swings due to the cam action of the intake camshaft 5 to open and close the intake valve 103. Similarly, a rocker arm 102, one end of which is supported by the hydraulic lash adjuster 37, swings due to the cam action of the exhaust camshaft 6 to open and close the exhaust valve 104. 105 indicates a fuel injection valve, and 106 indicates an ignition plug. The hydraulic lash adjuster itself is a well-known structure, so a detailed description is omitted, but it is roughly cylindrical, and is expanded by an internal spring to make the valve clearance zero, and the reaction force during valve lift is supported by the oil that fills the inside. Note that FIG. 6 is an explanatory diagram of the mechanism, and does not show the exact layout of each part.

In Figure 3, line M1 indicates the center line of the valve stem of the intake valve, and line M2 indicates the center line of the valve stem of the exhaust valve. As shown in Figure 3, the intake valve center line M1 passes inside in the width direction of the cylinder head 1 (left-right direction in Figure 3) of the center O1 of the intake camshaft 5. On the other hand, the exhaust valve center line M2 passes outside in the width direction of the cylinder head 1 of the center O2 of the exhaust camshaft 6.

Hydraulic lash adjusters

36, 37 are provided for each of the intake valves and exhaust valves. These

hydraulic lash adjusters

36, 37 are loaded into cylindrical lash

adjuster mounting holes

38, 39 provided in the cylinder head 1 and receive hydraulic pressure.

The intake side hydraulic lash adjuster 36 is located on the outside of the intake valve center line M1 in the width direction of the cylinder head 1, and in the illustrated example, is located approximately directly below the intake camshaft 5. The exhaust side hydraulic lash adjuster 37 is located on the inside of the exhaust valve center line M2 in the width direction of the cylinder head 1, and in the illustrated example, is located at a relatively higher position than the intake side hydraulic lash adjuster 36.

The in-line three-cylinder cylinder head 1 is equipped with six intake hydraulic lash adjusters 36 and six exhaust hydraulic lash adjusters 37. The lash

adjuster mounting holes

38, 39 are connected to lash

adjuster oil galleries

41, 42 that extend in the cylinder row direction, respectively. The lash

adjuster oil galleries

41, 42 are drilled, for example, along the cylinder row direction, and the ends of the lash

adjuster oil galleries

41, 42 shown in Figure 1 are blocked by plugs.

Next, the configuration of the oil passages, which are an essential part of the present invention, will be described with reference to Figure 4. Figure 4 shows the oil passages as seen through along the cylinder row direction in order to show the oil passages present inside the cylinder head 1 and cam carrier 2. Most of these oil passages, except for the lash

adjuster oil galleries

41, 42, are formed in the front end portions (the lower portions in Figure 2) of the cylinder head 1 and cam carrier 2. Note that, like the lash

adjuster oil galleries

41, 42, these oil passages are constructed by a combination of linear drilling, with unnecessary open ends blocked by plugs.

An oil source pressure passage 45 extending in the vertical direction is formed in approximately the center of the width of the cylinder head 1, in other words, at a position between the intake camshaft 5 and the exhaust camshaft 6 when viewed in the cylinder axial direction. The lower end of this oil source pressure passage 45 communicates with the main oil gallery (not shown) of the cylinder block 3. Therefore, oil pressurized by the oil pump is supplied to this oil source pressure passage 45.

The upper end of the oil source pressure passage 45 opens into the underside of an oil reservoir 46 formed at the top of the cylinder head 1. The oil reservoir 46 is formed as a bathtub-shaped recess in the joint surface with the cam carrier 2 at a position between the intake camshaft 5 and the exhaust camshaft 6 (see FIG. 5), and is formed as a closed space by being covered by the underside of the cam carrier 2. The joint surface 47 between the cylinder head 1 and the cam carrier 2 around the oil reservoir 46 is sealed with an appropriate sealing member such as the liquid gasket mentioned above.

The side surface 46a of the oil reservoir 46 on the exhaust camshaft 6 side is formed as an inclined surface as shown in FIG. 4, and one end of the exhaust-side oil passage 51 opens in the center of this side surface 46a. The exhaust-side oil passage 51 is formed in a straight line inclined, for example, at an angle of about 40 to 50 degrees with respect to the joint surface 47 (in other words, the top surface of the cylinder head 1), and its tip is connected to the exhaust-side lash adjuster oil gallery 42. In other words, oil is supplied to the exhaust-side lash adjuster mounting hole 39 from the oil reservoir 46 via the exhaust-side oil passage 51 and the lash adjuster oil gallery 42.

On the other hand, the cam carrier 2 has a cam carrier internal passage 52 formed by connecting multiple straight sections so as to pass through the inside of the cam carrier 2 as part of the oil passage from the oil reservoir 46 to the intake side hydraulic lash adjuster 36. The cam carrier internal passage 52 is composed of a straight section 52a extending diagonally upward from the oil reservoir 46, a straight section 52b extending parallel to the joint surface 47 above the intake camshaft 5, and a straight section 52c extending downward outside the intake camshaft 5 in the width direction of the cylinder head 1. In other words, the cam carrier internal passage 52 has an inlet section 52d facing the oil reservoir 46 between the two

camshafts

5, 6, and an outlet section 52e facing the top surface of the cylinder head 1 outside the two

camshafts

5, 6. In addition, in the middle of the straight section 52c that extends parallel to the joint surface 47, a camshaft lubricating oil passage 56 is formed that branches off from the cam carrier internal passage 52 and leads to the intake side camshaft bearing portion 11 for the intake camshaft 5. The journal portion of the intake camshaft 5 is lubricated by the oil that flows through this camshaft lubricating oil passage 56.

An intake-side oil passage 53 is formed on the cylinder head 1 side so as to connect to the outlet 52e of the cam carrier internal passage 52. The intake-side oil passage 53 has a straight section 53a extending vertically and a straight section 53b extending diagonally downward from the outer periphery of the cylinder head 1. The tip of the straight section 53b is connected to the intake-side lash adjuster oil gallery 41. The periphery of the connection between the two is also sealed by a seal member at the joint surface 47 between the cylinder head 1 and the cam carrier 2. Figure 5 shows the upper end opening of the intake-side oil passage 53 (straight section 53a). Therefore, oil is supplied to the intake-side lash adjuster mounting hole 38 from the oil reservoir 46 via the cam carrier internal passage 52, the intake-side oil passage 53, and the lash adjuster oil gallery 41.

In this way, in the above embodiment, oil is supplied from the oil reservoir 46 to the intake side lash adjuster mounting hole 38 through the cam carrier internal passage 52. Therefore, compared to forming all the necessary oil passages inside the cylinder head 1, the layout of the oil passages is easier, and the oil passages can be provided while avoiding interference with other components. For example, an intake valve is interposed between the oil source pressure passage 45 and the intake side lash adjuster mounting hole 38 (see FIG. 6), but by providing the cam carrier internal passage 52 inside the cam carrier 2, it is possible to lay out the oil passages while avoiding interference with the intake valve. Furthermore, because the cam carrier internal passage 52 crosses above the intake camshaft 5, it is not necessary to form an oil passage that crosses below the camshaft 5 on the cylinder head 1 side.

In addition, the cam carrier internal passage 52 is located higher than the hydraulic lash

adjusters

36, 37, and forms a relatively long path to the hydraulic lash

adjusters

36, 37. This contributes to oil retention while the internal combustion engine is stopped, and improves oil retention, for example, when the internal combustion engine is left unused for an extended period of time. As a result, when the internal combustion engine is started after being left unused, oil is quickly supplied to the hydraulic lash

adjusters

36, 37, preventing oil shortage and air intake.

The exhaust-side hydraulic lash adjuster 37 is located between the exhaust valve and the oil source pressure passage 45, so by providing the exhaust-side oil passage 51 in a straight line from the central oil reservoir 46 as described above, a simple structure can be achieved. For the exhaust-side hydraulic lash adjuster 37, there is no passage with an oil retention function that passes through the inside of the cam carrier 2, but since the oil is retained by the oil reservoir 46, oil shortage and air intake are suppressed. Therefore, there are separate parts with an oil retention function for the intake-side hydraulic lash adjuster 36 and the exhaust-side hydraulic lash adjuster 37, and oil shortage in each is reliably suppressed.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications are possible. For example, the cam carrier is not limited to a ladder-shaped configuration as in the above embodiment, but may be any configuration that has at least one camshaft bearing portion. In addition, the camshaft may be rotatably supported between the cylinder head 1 and the cam carrier.

Claims

A cylinder head;
a first camshaft and a second camshaft, one of which is for an intake valve and the other is for an exhaust valve;
a hydraulic lash adjuster disposed in the cylinder head corresponding to at least the first camshaft;
a cam carrier fixed to an upper portion of the cylinder head and supporting at least a first camshaft;
A cylinder head structure for an internal combustion engine comprising:
When viewed in the cylinder axial direction, an oil source pressure passage is located inside the cylinder head between the first camshaft and the second camshaft,
A part of the oil passage from the oil source pressure passage to the hydraulic lash adjuster passes through the inside of the cam carrier as a cam carrier internal passage.
Cylinder head structure of an internal combustion engine.
The cam carrier internal passage extends from an inlet portion between the two camshafts across above the first camshaft to an outlet portion outside the two camshafts when viewed in the cylinder axial direction.
2. The cylinder head structure of an internal combustion engine according to claim 1.
The cylinder head has an oil gallery for the lash adjuster extending along the cylinder row direction inside the cylinder head.
an oil gallery for the lash adjuster is connected between the outlet of the cam carrier internal passage and the hydraulic lash adjuster;
3. A cylinder head structure for an internal combustion engine according to claim 2.
a camshaft lubricating oil passage branching from the cam carrier internal passage inside the cam carrier and leading to a camshaft bearing portion;
3. A cylinder head structure for an internal combustion engine according to claim 2.
The oil source pressure passage has an oil reservoir portion formed so as to expand in volume at a joint surface between the cylinder head and the cam carrier,
a second hydraulic lash adjuster disposed in the cylinder head corresponding to the second camshaft is in communication with the oil reservoir via a second oil passage;
2. The cylinder head structure of an internal combustion engine according to claim 1.