Cylinder head structure of an internal combustion engine

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

Technical Field

[0001] The present invention relates to a cylinder head structure of an internal combustion engine provided with a hydraulic lash adjuster, and more particularly to an improvement in the layout of an oil passage for supplying oil to the lash adjuster.

Background Art

[0002] In a valve operating mechanism of an intake valve or an exhaust valve of an internal combustion engine, a hydraulic lash adjuster is known for automatically adjusting the valve clearance to zero. In a configuration in which this hydraulic lash adjuster is provided in a cylinder head, an oil passage for guiding oil supplied from the cylinder block side to the hydraulic lash adjuster is generally required.

[0003] Patent Document 1 discloses a configuration in which an oil reservoir portion covered by a cam cap member is formed between an intake camshaft and an exhaust camshaft of a cylinder head, and an oil passage is formed from the lower portion of this oil reservoir portion to a hydraulic lash adjuster.

[0004] As disclosed in this Patent Document 1, conventionally, the entire oil passage for the hydraulic lash adjuster is formed inside the cylinder head by, for example, drilling, etc. Therefore, the design freedom is low, and the arrangement of the oil passage may be difficult due to interference with other parts.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] The present invention is 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 positioned in the cylinder head corresponding to at least the first camshaft, A cam carrier fixed to the top 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 direction of the cylinder axis, the oil pressure passage inside the cylinder head is located between the first camshaft and the second camshaft. A portion of the oil passage leading from this oil source pressure passage to the hydraulic lash adjuster passes through the inside of the cam carrier as an internal passage within the cam carrier.

[0007] 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. Therefore, there are fewer constraints on the placement of the oil passage due to interference with other parts on the cylinder head side.

[0008] Furthermore, the cam carrier is located relatively high in the vertical position of the internal combustion engine, and the vertical distance to the lash adjusters is also long, so oil is retained even if the internal combustion engine has been left idle for a long period of time. Therefore, oil is reliably supplied to the lash adjusters from the initial stages of the next start. [Brief explanation of the drawing]

[0009] [Figure 1] Front view of a cylinder head with a cam carrier. [Figure 2] Plan view of the cam carrier. [Figure 3] Cross-sectional view of a cylinder head equipped with a cam carrier. [Figure 4] An explanatory diagram showing the layout of the oil passages. [Figure 5] Top view of the cylinder head. [Figure 6] Diagram illustrating the valve train mechanism. [Modes for carrying out the invention]

[0010] An embodiment of this invention will now be described in detail with reference to the drawings. Figure 1 is a front view showing the cylinder head 1 of an internal combustion engine according to this invention together with the cam carrier 2. The cylinder head 1 is integrally cast using a metal material, such as an aluminum alloy, and is mounted on the upper surface of the cylinder block 3. The internal combustion engine of this embodiment is a three-cylinder in-line spark-ignition internal combustion engine, a so-called gasoline engine, which is mounted in a so-called transverse position at the front of the vehicle. When mounted on the vehicle, the cylinder center axis is generally vertical, and therefore Figure 1 generally corresponds to the position when mounted on the vehicle.

[0011] Furthermore, the internal combustion engine of the embodiment has a pent-roof type combustion chamber equipped with a spark plug and a fuel injection valve in the center of the combustion chamber, and each cylinder is equipped with a pair of intake valves and a pair of exhaust valves.

[0012] The cylinder head 1 includes an intake camshaft 5 for the intake valve and an exhaust camshaft 6 for the exhaust valve. The cam carrier 2 is configured as a cover that covers the upper opening of the cylinder head 1 and is joined and fixed to the upper surface of the cylinder head 1 via a suitable 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 approximately semicircular in shape and extend downwards, and rotatably supports the intake camshaft 5 and exhaust camshaft 6, respectively, between these camshaft bearing portions 11 and 12 and cam brackets 13 and 14 that are mounted opposite to them.

[0013] As shown in Figure 1, the intake camshaft 5 is positioned relatively lower than the exhaust camshaft 6 in terms of height along the cylinder's central axis. Correspondingly, the height of the upper edge portion of the cam carrier 2 covering the top of each camshaft 5 and 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 compartment at the front of the vehicle with the intake camshaft 5 side at the front of the vehicle and the exhaust camshaft 6 side at the rear of the vehicle. Therefore, the clearance between the engine and the vehicle's engine hood (shown by the dashed line L), which is inclined so that the front end is at a lower position, is appropriate for both the intake camshaft 5 side and the exhaust camshaft 6 side.

[0014] As shown in Figure 2, the cam carrier 2 of one embodiment has a ladder-like structure in which two elongated camshaft housings 21 and 22 extending in the direction of the cylinder row are connected to each other at the inter-cylinder positions. At three locations corresponding to the cylinder positions in the direction of the cylinder row, relatively large injection valve openings 23 are provided between the two camshaft housings 21 and 22. In addition, cylindrical plug holes 24 for inserting spark plugs are formed on the exhaust camshaft 6 side (camshaft housing 22 side) of the injection valve openings 23. The cam carrier 2 is integrally cast using a metal material such as an aluminum alloy.

[0015] 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. In Figure 3, the valve train is not shown, but as is well known to those skilled in the art, cylindrical stem guides are attached to the stem guide mounting holes 34 and 35, respectively, and poppet valve type intake and exhaust valves are assembled together with valve springs.

[0016] FIG. 6 is an explanatory diagram showing an outline of a valve operating mechanism not shown in FIG. 3. A rocker arm 101 having one end supported by a hydraulic lash adjuster 36 swings by the cam action of an intake camshaft 5 to open and close an intake valve 103. Similarly, a rocker arm 102 having one end supported by a hydraulic lash adjuster 37 swings by the cam action of an exhaust camshaft 6 to open and close an exhaust valve 104. 105 indicates a fuel injection valve and 106 indicates a spark plug. Since the hydraulic lash adjuster itself has a known configuration, its detailed description is omitted. It has a substantially cylindrical shape, extends by an internal spring to make the valve clearance zero, and is configured to be supported by oil filling the inside against the reaction force during valve lift. Note that FIG. 6 is an explanatory diagram of the mechanism and does not show the exact arrangement of each part.

[0017] In FIG. 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 FIG. 3, the intake valve center line M1 passes inside in the width direction of the cylinder head 1 (the left - right direction in FIG. 3) from 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 from the center O2 of the exhaust camshaft 6.

[0018] Hydraulic lash adjusters 36 and 37 are provided for each of the intake valve and the exhaust valve. These hydraulic lash adjusters 36 and 37 are loaded into cylindrical lash adjuster mounting holes 38 and 39 provided in the cylinder head 1 to receive hydraulic supply.

[0019] The intake - side hydraulic lash adjuster 36 is located outside in the width direction of the cylinder head 1 from the intake valve center line M1, and in the illustrated example, is arranged at a position substantially directly below the intake camshaft 5. The exhaust - side hydraulic lash adjuster 37 is located inside in the width direction of the cylinder head 1 from the exhaust valve center line M2, and in the illustrated example, is provided at a relatively higher position than the intake - side hydraulic lash adjuster 36.

[0020] In the entire in-line 3-cylinder cylinder head 1, six intake-side hydraulic lash adjusters 36 and six exhaust-side hydraulic lash adjusters 37 are provided. The lash adjuster mounting holes 38, 39 communicate with lash adjuster oil galleries 41, 42 extending in the cylinder bank direction, respectively. The lash adjuster oil galleries 41, 42 are, for example, drilled along the cylinder bank direction, and the ends of the lash adjuster oil galleries 41, 42 depicted in FIG. 1 are closed by plugs.

[0021] Next, the configuration of the oil passage, which is the main part of the present invention, will be described with reference to FIG. 4. FIG. 4 shows the oil passage in a perspective view along the cylinder bank direction to show the oil passages existing inside the cylinder head 1 and the cam carrier 2. Most of these oil passages other than the lash adjuster oil galleries 41, 42 are formed at the front end portions (the lower portions in FIG. 2) of the cylinder head 1 and the cam carrier 2. Similar to the lash adjuster oil galleries 41, 42, these oil passages are constituted by a combination of linear drilling processes, and unnecessary open end portions are closed by plugs.

[0022] An oil source pressure passage 45 extending in the vertical direction is formed at a substantially central portion in the width direction 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 axis direction. The lower end portion of this oil source pressure passage 45 communicates with a main oil gallery (not shown) of the cylinder block 3. Therefore, the oil pressurized by the oil pump is supplied to this oil source pressure passage 45.

[0023] The upper end of the oil pressure passage 45 opens to the lower surface of the oil reservoir 46 formed on the upper part of the cylinder head 1. The oil reservoir 46 is formed as a bathtub-shaped recess at the joint surface with the cam carrier 2 at a position between the intake camshaft 5 and the exhaust camshaft 6 (see Figure 5), and is formed as a closed space by being covered by the lower surface 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 by a suitable sealing member such as the liquid gasket described above.

[0024] As shown in Figure 4, the side surface 46a of the oil reservoir 46 on the exhaust camshaft 6 side is formed as an inclined surface, 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 at, for example, about 40 to 50° with respect to the joint surface 47 (in other words, the upper surface of the cylinder head 1), and its tip communicates with 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.

[0025] On the other hand, the cam carrier 2 has an internal cam carrier 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 internal cam carrier passage 52 consists 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 outward in the width direction of the cylinder head 1 from the intake camshaft 5. In other words, the internal cam carrier passage 52 has an inlet 52d facing the oil reservoir 46 between the two camshafts 5 and 6, and an outlet 52e facing the upper surface of the cylinder head 1 outside the two camshafts 5 and 6. Furthermore, in the middle of the straight section 52c that extends parallel to the joint surface 47, a camshaft lubrication oil passage 56 is formed, branching off from the cam carrier internal passage 52 and leading to the intake side camshaft bearing section 11 for the intake camshaft 5. The journal portion of the intake camshaft 5 is lubricated by the oil flowing through this camshaft lubrication oil passage 56.

[0026] An intake-side oil passage 53 is formed on the cylinder head 1 side so as to connect to the outlet portion 52e of the cam carrier internal passage 52 described above. The intake-side oil passage 53 has a straight section 53a that extends vertically and a straight section 53b that extends diagonally downward from the outer circumference of the cylinder head 1. The tip of the straight section 53b communicates with the intake-side lash adjuster oil gallery 41. The area around the connection between the two is sealed by a sealing 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.

[0027] As described above, in this 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 the case where the entire necessary oil passage is formed inside the cylinder head 1, the layout of the oil passage is easier, and the oil passage can be provided while avoiding interference with other parts. For example, an intake valve is interposed between the oil source pressure passage 45 and the intake-side lash adjuster mounting hole 38 (see Figure 6), but by providing the cam carrier internal passage 52 inside the cam carrier 2, it is possible to lay out the oil passage while avoiding interference with the intake valve. Furthermore, since the cam carrier internal passage 52 crosses above the intake camshaft 5, it is unnecessary to form an oil passage that crosses below the camshaft 5 on the cylinder head 1 side.

[0028] Furthermore, the internal passage 52 of the cam carrier is located higher than the hydraulic lash adjusters 36 and 37 and forms a relatively long path to the hydraulic lash adjusters 36 and 37. Therefore, it contributes to oil retention while the internal combustion engine is stopped, improving oil retention, for example, when the internal combustion engine is left idle for a long period of time. As a result, when the internal combustion engine is started after being idle, oil is quickly supplied to the hydraulic lash adjusters 36 and 37, suppressing oil depletion and air intake.

[0029] Since the exhaust-side hydraulic lash adjuster 37 is located between the exhaust valve and the oil source pressure passage 45, a simple structure can be achieved by providing the exhaust-side oil passage 51 in a straight line from the central oil reservoir 46 as described above. Although there is no passage with an oil retention function that passes through the inside of the cam carrier 2 for the exhaust-side hydraulic lash adjuster 37, the oil is retained by the oil reservoir 46, so oil depletion and air intake are suppressed. Therefore, there are separate parts with oil retention functions for the intake-side hydraulic lash adjuster 36 and the exhaust-side hydraulic lash adjuster 37, and oil depletion is reliably suppressed for each.

[0030] 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-like configuration as in the above embodiment, but may have at least one camshaft bearing portion. Alternatively, the camshaft may be rotatably supported between the cylinder head 1 and the cam carrier.

Claims

1. Cylinder head and, A first camshaft and a second camshaft, one of which is for the intake valve and the other for the exhaust valve, A first hydraulic lash adjuster is positioned in the cylinder head corresponding to the first camshaft, A second hydraulic lash adjuster is positioned in the cylinder head in accordance with the second camshaft, A cam carrier fixed to the top of the cylinder head and supporting at least a first camshaft, A cylinder head structure for an internal combustion engine, comprising: The first hydraulic lash adjuster described above is located outside the width direction of the internal combustion engine, relative to the centerline of the valve stem of the corresponding intake or exhaust valve. The second hydraulic lash adjuster described above is positioned in the width direction of the internal combustion engine between the centerline of the intake valve stem and the centerline of the exhaust valve stem. When viewed in the direction of the cylinder axis, the oil pressure passage inside the cylinder head is located between the first camshaft and the second camshaft. A portion of the oil passage from this oil source pressure passage to the first hydraulic lash adjuster passes through the inside of the cam carrier as an internal passage of the cam carrier. The above-mentioned oil pressure passage extends vertically inside the cylinder head and is connected to the above-mentioned cam carrier internal passage at the joint surface between the cylinder head and the cam carrier. The above-mentioned internal passage of the cam carrier, when viewed in the cylinder axial direction, crosses above the first camshaft and connects to the internal oil passage of the cylinder head for the first hydraulic lash adjuster. The second hydraulic lash adjuster is connected to the oil source pressure passage via an internal oil passage in the cylinder head for the second hydraulic lash adjuster, without passing through the cam carrier. Cylinder head structure of an internal combustion engine.

2. (delete)

3. The cylinder head has an oil gallery for the lash adjuster that extends along the direction of the cylinder row. The oil gallery for the lash adjuster is connected between the internal passage of the cam carrier and the first hydraulic lash adjuster. The cylinder head structure for an internal combustion engine according to claim 1.

4. The above-mentioned cam carrier is provided with a camshaft lubrication oil passage that branches off from the internal passage of the cam carrier and reaches the camshaft bearing section. The cylinder head structure for an internal combustion engine according to claim 1.

5. The above-mentioned oil pressure passage has an oil reservoir formed such that its volume increases at the joint surface between the cylinder head and the cam carrier. The oil passage inside the cylinder head for the second hydraulic lash adjuster mentioned above is in communication with the oil reservoir mentioned above. The cylinder head structure for an internal combustion engine according to claim 1.

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