United States Patent (19) 11 Patent Number: 4,784,091 Okada, deceased et al. (45) Date of Patent: Nov. 15, 1988

(54 HEAD COVER STRUCTURE FOR 3,303,832 2/1967 Platner et al...... 123/52 M A V-TYPE ENGINE 3,782,344 1/1974 Schmuck ...... 123/52 M 4,440,120 4/1984 Butler ...... 123/52 MV (75) Inventors: Masatoshi Okada, deceased, late of 4,643,138 2/1987 Ruf et al...... 123/52 M Kariya, Japan, by Masayuki Okada a legal representative; Masami Primary Examiner-Willis R. Wolfe Nishida; Kazuaki Hokazono, both of Assistant Examiner-Marguerite Macy Hiroshima, Japan Attorney, Agent, or Firm-Gerald J. Ferguson, Jr. 73) Assignee: Mazda Motor Corporation, 57 ABSTRACT Hiroshima, Japan Each of the cylinder heads forming right and left cylin 21) Appl. No.: 35,330 der banks of a V-type engine is provided, in the inner side wall thereof, with ports each communicating 22 Filed: Apr. 7, 1987 with a cylinder formed in the cylinder bank. A 30 Foreign Application Priority Data is provided in each cylinder bank above intake and exhaust valves to drive the valves in synchronization Apr. 8, 1986 JP Japan ...... 61-80586 with the rotation of the engine and supported for rota (51 Int. Cl." ...... FO2M 35/10 tion by a plurality of bearings. Each discrete intake 52 U.S. Cl...... 123/52 MV; 123/90.38 passage is connected to one of the intake port of one of (58) Field of Search ...... 123/193 H, 52 M., 52 MV, the cylinder banks and extends above the other cylinder 123/90.27, 90.38 bank. covers mounted on the respective cylinder heads are provided with recessed portions at (56) References Cited the portions corresponding to the inter-bearing portions U.S. PATENT DOCUMENTS of the camshaft and said discrete intake passages extend 1,132,256 3/1915 Gunn ...... 123/90.38 through the recessed portions. 2,845,911 8/1958 Gill ...... 123/52 MV 2,990,819 7/1961 Bouvy ...... 123/90.38 12 Claims, 3 Drawing Sheets

U.S. Patent Nov. 15, 1988 Sheet 1 of 3 4,784,091

U.S. Patent Nov. 15, 1988 Sheet 2 of 3 4,784,091

U.S. Patent Nov. 15, 1988 Sheet 3 of 3 4,784,091

4,784,091 1. n 2 FIG. 4 is a cross-sectional view taken along line CYLINDER HEAD COVER STRUCTURE FOR A IV-IV in FIG. 2. V. TYPE ENGINE DESCRIPTION OF THE PREFERRED BACKGROUND OF THE INVENTION 5 EMBODIMENT 1. Field of the Invention In FIG. 1, a V-type engine has a cylinder block 1 on which a cylinder head 2 for the left cylinder bank L and This invention relates to a cylinder head cover struc a cylinder head 3 for the right cylinder bank R are ture for a V-type engine, and more particularly to a mounted at 60 to each other. Between the cylinder cylinder head cover structure which can contribute to 10 block 1 and the cylinder head 2 for the left cylinder the enhancement of the supercharging effect of the bank L and between the cylinder block 1 and the cylin inertia of the intake air in a V-type engine. der head 3 for the right cylinder bank R are each 2. Description of the Prior Art formed three cylinders 4. A (not shown) is in There has been known, as disclosed in Japanese Un serted into each cylinder 4 to form a combustion cham examined Patent Publication No. 59(1984)-565, an in 15 ber 5 therein. take system for a V-type engine in which the intake The cylinder heads 2 and 3 are provided with an ports are formed in the inner sides (opposed sides) of the intake port 6 and an exhaust port 7 for each cylinder 4. cylinder banks, and the intake passages connected to the Each of the intake ports 6 opens to the combustion intake ports of each bank extend to the inner side of the chamber 5 at one end and to the inner side wall of the other bank and then are bent upwardly to form an arc in 20 corresponding cylinder bank at the other end. Each of a vertical plane, thereby ensuring a sufficient length of the exhaust ports 7 opens to the 5 the intake passages with the best use of the space be at one end and to the outer side wall of the correspond tween the banks and improvement of the inertia effect ing cylinder bank at the other end. The intake port 6 is of intake air. provided with an intake valve 8 at the end facing the However, the intake system of the prior art is disad 25 combustion chamber 5 and the exhaust port 7 is pro vantageous in that since the angle at which the cylinder vided with an exhaust valve 9 at the end facing the banks are set to each other is substantially fixed and the combustion chamber 5. Each of said intake valves 8 is intake passages are laid out in the space between the mounted inwardly inclined with respect to the central cylinder banks, the intake passages must be inherently axis of the cylinder 4. Each of the cylinder heads 2 and elongated upward in order to ensure a sufficient length, 30 3 is provided with a camshaft 10 for exclusively driving thereby adding to the overall height of the engine. the intake valves 8 and a camshaft 11 for exclusively driving the exhaust valves 9. The 10 and 11 SUMMARY OF THE INVENTION are disposed substantially on the extension of the longi In view of the foregoing observations and descrip tudinal axes of the valve stems of the intake valves 8 and tion, the primary object of the present invention is to 35 extend in parallel to the row of cylinders. The camshaft provide a cylinder head cover structure in which a 10 on each cylinder head is supported by four camshaft sufficient length of the intake passages can be ensured bearings 12 and the camshift 11 on each cylinder head is without adding to the overall height of the engine. supported by four camshaft bearing 13. As shown in In accordance with the present invention, there is FIG. 2, one of the four camshaft bearings 12 is disposed provided a cylinder head cover structure for a V-type on the front end of the corresponding cylinder head, engine having first and second cylinder heads for form and the other three camshift bearings 12 are respec ing first and second cylinder banks, each cylinder head tively disposed beside the three cylinders 4. Similarly, being provided, in the inner side wall thereof, with one of the four camshaft bearings 13 is disposed on the intake ports each communicating with a cylinder front end of the corresponding cylinder head, and the 45 other three camshaft bearings 13 are respectively dis formed in the cylinder bank, at least one camshaft pro posed beside the three cylinders 4. Further, the cylinder vided in each cylinder bank above intake and exhaust heads 2 and 3 are respectively provided with cylinder valves to drive the valves in synchronization with rota head covers 14 and 15 to cover the camshafts 10 and 11. tion of the engine and supported for rotation by a plu To each of the intake ports 6 is connected one end of rality of bearings, discrete intake passages each of 50 a discrete intake passage 16 the other end of which is which is connected to one of the intake ports of one of connected to a surge tank 17 disposed between the the cylinder banks and extends above the other cylinder banks L and R. The downstream side portion 16a of the bank, and cylinder head covers mounted on the respec discrete intake passage 16 connected to each intake port tive cylinder heads, characterized in that recessed por 6 in each cylinder bank extends from the intake port 6 tions are formed in each of the cylinder head covers at 55 toward the other cylinder bank, and the upstream side the portions corresponding to the inter-bearing portions portion 16b of the discrete intake passage 16 is disposed of the camshaft and said discrete intake passages extend above the camshaft 10 for exclusively driving the intake through the recessed portions. valves 8 of said other cylinder bank and is bent up BRIEF DESCRIPTION OF THE DRAWINGS wardly to form an arc in a vertical plane toward a side 60 of the surge tank 17. FIG. 1 is a cross-sectional view showing a V-type Each of the cylinder head covers 14 and 15 is pro engine provided with a cylinder head cover structure in vided with recessed portions 18 at portions correspond accordance with an embodiment of the present inven ing to the inter-bearing portions of the camshaft 10 (the tion, portions between the camshaft bearings 12) as shown in FIG. 2 is a plan view showing the right cylinder bank 65 FIGS. 1 to 4, and the upstream side portions 16b of the of the engine, discrete intake passages 16 are passed through one of FIG. 3 is a cross-sectional view taken along line III the recessed portions 18 not to interfere with the cylin -III in FIG. 2, and der head cover. 4,784,091 3 4. By virtue of the recessed portions 18, the overall and is bent downward above the respective camshaft length of each discrete intake passage 16 can be suffi for the cylinder bank to extend through one of the re cient to obtain an optimal inertia effect of intake air in a cessed portions in the cylinder head cover toward the low engine speed range without adding to the overall other cylinder bank where it is connected to one of the height of the engine. intake ports, and a crossing portion connected to one of We claim: the intake ports in said other cylinder bank at a down 1. A cylinder head cover structure for a cylinder stream end thereof and to a downstream end of the engine having first and second cylinder heads for form U-shaped portion at an upstream end, the crossing por ing first and second cylinder banks, each cylinder head tions of the discrete intake passages for the respective being provided, in an inner side wall thereof, with in 10 cylinder banks being located below the surge tank and take ports each communicating with a cylinder formed crossing each other when viewed in a direction parallel in the cylinder bank, at least one camshaft provided in to an engine output shaft. each cylinder bank above intake and exhaust valves to 9. A cylinder head cover structure for a cylinder drive the valves in synchronization with rotation of the engine having first and second cylinder heads for form engine and supported for rotation by a plurality of bear 15 ing first and second cylinder banks, each cylinder head ings, discrete intake passages each of which is con being provided, in an inner side wall thereof, with in nected to one of the intake ports of one of the cylinder take ports each communicating with a cylinder formed banks and extends above the other cylinder bank, and in the cylinder bank, a pair of intake valves for each cylinder head covers mounted on the respective cylin cylinder, at least one exhaust valve for each cylinder, a der heads, characterized in that recessed portions are 20 formed in each of the cylinder head covers at corre pair of camshafts provided in each cylinder bank to sponding portions of the camshaft and respective said respectively drive the intake valves and the exhaust discrete intake passages extend through corresponding valves in synchronization with rotation of the engine, a ones of said recessed portions. plurality of camshaft bearings formed in each cylinder 2. A cylinder head cover structure as defined in claim 25 head between the intake valves for each cylinder, dis 1 in which said camshaft is disposed substantially on an crete intake passages each of which is connected to one extension of the longitudinal axis of valve stems of the of the intake ports of one of the cylinder banks and intake valves. extends above the other cylinder bank, and cylinder 3. A cylinder head cover structure as defined in claim head covers mounted on the respective cylinder heads, 2 in which each of said intake valves is mounted in 30 characterized in that recessed portions are formed in wardly inclined with respect to the central axis of the each of the cylinder head covers at inter-cylinder por cylinder. tions of the camshaft and respective said discrete intake 4. A cylinder head cover structure as defined in claim passages extend through corresponding ones of said 1 in which said intake valves in each cylinder bank are recessed portions. driven by an intake camshaft and the exhaust valves in 35 10. A cylinder head cover structure as defined in each cylinder bank are driven by an exhaust camshaft, claim 9 in which each of said discrete intake passages is and said recessed portions are formed in each of the connected to a surge tank having a predetermined vol cylinder head covers at the inter-bearing portions of the ume at an upstream end thereof, and extends from the intake camshaft. surge tank toward one of the cylinder banks and is bent 5. A cylinder head cover structure as defined in claim 40 downward above the respective camshaft for the cylin 4 in which a pair of intake valves are provided for each der bank to extend through one of the recessed portions cylinder, and the bearings for supporting the intake in the cylinder head cover toward the other cylinder camshaft are provided between for each cylinder, bank where it is connected to one of the intake ports. said recessed portions being formed at portions of the 11. A cylinder head cover structure as defined in cylinder head cover corresponding to the portions of 45 claim 10 in which each of said discrete intake passages the intake camshaft between the cams for two adjacent is formed by a U-shaped portion which extends from a cylinders. side of the surge tank toward one of the cylinder banks 6. A cylinder head cover structure as defined in claim and is bent downward above the respective intake 1 in which said first and second cylinder banks are set at shaft for the cylinder bank to extend through one of the 60. 50 recessed portions in the cylinder head cover toward the 7. A cylinder head cover structure as defined in claim other cylinder bank where it is connected to one of the 1 in which each of said discrete intake passages is con intake ports, and a crossing portion connected to one of nected to a surge tank having a predetermined volume the intake ports in the other cylinder bank at a down at an upstream end thereof, and extends from the surge stream end thereof and to a downstream end of the tank toward one of the cylinder banks and is bent down 55 U-shaped portion at an upstream end, the crossing por ward above the respective camshaft for the cylinder tions of the discrete intake passages for the respective bank to extend through one of the recessed portions in cylinder banks being located below the surge tank and the cylinder head cover toward the other cylinder bank crossing each other when viewed in a direction parallel where it is connected to one of the intake ports. to an engine output shaft. 8. A cylinder head cover structure as defined in claim 60 12. A cylinder head cover structure as defined in 7 in which each of said discrete intake passages is claim 9 in which said first and second cylinder banks are formed by a U-shaped portion which extends from a set at 60. side of the surge tank toward one of the cylinder banks sk s

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