Internal combustion engine

Abstract: The invention relates to an internal combustion engine (1) for vehicles comprising an output shaft (16) disposed in parallel with the crankshaft of the engine for transmitting the output power to the wheel shafts of the vehicle. The present invention is characterized in that the accessory drive pulley (50) supported by the output shaft (16) is located laterally opposite a crankshaft bearing and, preferably, disposed to be at least partially accommodated through a concave formed at the position of the crankshaft bearing (60).

Description: The invention relates to an internal combustion engine comprising an output shaft which is disposed in parallel with the crankshaft of the engine with an accessory drive pulley mounted on said output shaft. More specificially, the invention relates to an internal combustion engine designed to render the engine compact reducing its length in the direction of the crankshaft and its width in a direction transverse to the crankshaft axis. Recently, automotive structures have been deviced with an intention for making its engine unit compact by reducing its width longitudinally and laterally of its crankshaft to make the engine compartment as small as possible and as much to make the passenger compartment spacious so that the roominess and amenity for passengers may be afforded. Usually the accessory or auxiliary drive pulley for driving the accessories such as an alternator, a power steering pump, an air compressor, etc. are driven by an accessory driving system mounted on the crankshaft so as to drive said accessories by the power of the engine derived from the revolution speed of the crankshaft. Since such an accessory drive system is disposed at the end of the crankshaft, the disadvantage occurs that the length of the engine in the direction of the crankshaft axis is increased in the amount of the accessory drive system, normally designed to be an auxiliary or accessory drive pulley. In order to avoid such undesirable increase of the length of the motor block, efforts have been made to overcome said problems by disposing the accessory drive pulley within the extent of the crankshaft. As shown in EP-A-0335246, which belongs to the state of the art under Article 54 (3) EPC, a solution of said problem has been found in that the accessory drive pulley has been mounted on the output shaft of the engine which is disposed in parallel to the crankshaft. Said output shaft takes the engine performance from the crankshaft through a drive train and is adapted to transmit the engine output to the wheel shafts via a clutch mechanisam and a transmission. On the other hand, upon locating the accessory pulley on the output shaft, difficulties have been experienced to design the engine under space-saving aspects, namely, intending to reduce the dimension of the engine in width-wise direction, i.e., in a direction transverse to the crankshaft axis. In this case, locating the output shaft as close to the cylinder block/crankcase structure as desirable, the accessory drive pulley would interfere with certain parts of the engine such as the cylinder block supporting the crankshaft and/or the bearing case. Accordingly, the disposal of the accessory drive pulley on the output shaft of the engine has led to a definite and relatively large distance in between the output shaft and the crankshaft as the output shaft has to be kept spaced from the crankshaft or surrounding portions of the motor block resulting avoidably in an increased engine width in a direction transverse to the crankshaft axis, rendering the engine unit bulky in as much as an increased distance inbetween the crankshaft and the output shaft is required. Accordingly, it is an objective of the present invention to design an internal combustion engine as indicated above in such a manner that the engine becomes more compact and small-sized having a reduced length in the direction of the crankshaft axis but having a minimal dimension in width-wise direction perpendicularly to the crankshaft axis as well, even though an accessory drive pulley is disposed on an output shaft of the engine. In order to achieve the afore-indicated objective, according to the present invention, an internal combustion engine is provided comprising an engine block and a bearing case for supporting a crankshaft, an output shaft disposed in parallel with the crankshaft and supporting an accessory drive pulley adapted to drive accessory devices, wherein the accessory drive pulley is at least partially accommodated through a concave, formed into an outer surface of the cylinder block and/or bearing case, said outer surface extending substantially in parallel to the crankshaft, said concave is formed at a position of a crankshaft bearing which is opposite to said auxiliary drive pulley. According to another advantageous embodiment of the present invention, said concave is formed at the position of an end main bearing of the crankshaft supporting structure or at a spaced intermediate main bearing section with the concave being recessed at the cylinder block and/or bearing case (crankcase) of the automotive engine. With the present invention, the advantageous effect of both reducing the axial length of the engine in direction of the cam shaft axis and reducing the bulkiness of the cylinder block in width-wise direction rectangular to the crankshaft axis is obtained by means of disposing the output shaft in parallel with the crankshaft in order to transfer the engine output power to a transmission via a clutch mechanism and, supporting the auxiliary or accessory drive pulley on said output shaft along the extent of the crankshaft at certain selected locations, namely laterally opposite to a bearing of the crankshaft. Accordingly, in compliance with a preferred embodiment of the present invention, the accessory drive pulley is at least partially accommodated within a concave formed at the position of crankshaft bearing through the cylinder block/crankcase structure, said bearing being opposite to the accessory drive pulley. Therefore, the distance between the crankshaft and the output shaft is kept minimal despite the arrangement of the accessory drive pulley within the extent of the crankshaft laterally of one of the crankshaft bearings. The output shaft serves or may serve to different purposes such as an oil pump drive means, water pump drive means, cam shaft and alternator drive means in addition to transmitting the output power from the crankshaft to the wheel shafts via a transmission, or alternately thereto. Further preferred embodiments of the present invention are set forth in the other subclaims. Further objectives, features and advantages of the present invention will become more apparent from the following description of specific embodiments of the present invention in conjunction with the associated drawings wherein: Figure 1 is a side view of an automotive internal combustion engine according to the present invention as mounted as transverse engine into an engine compartment, Figure 2 is a diagramatic plan view of the engine according to Figure 1 mounted as a transverse engine into an engine compartment, Figure 3 is a side view of the automotive internal combustion engine according to Figure 1, but from the opposite side, Figure 4 is a front view of the automotive internal combustion engine as shown in Figure 1, Figure 5 is a partially broken away side view of the automotive internal combustion engine as shown in Figure 1, Figure 6 is a sectional view along the line VI-VI in Figure 5, partially in a diagramatic illustration, Referring first to Figures 1 and 2, an engine compartment of a motor vehicle adapted to accommodate an internal combustion engine according to an embodiment of the present invention is denoted by reference numeral 1. In this case, the vehicle equipped with an engine embodying the invention is of the front engine, front wheel drive type wherein the engine compartment 1 is formed above and between the right and left wheels 3 connected through front wheel shafts 2 connected to the front drive power train of the vehicle. Within the engine compartment 1 as an engine unit 4 a four-stroke six cylinder internal combustion engine is mounted with its radiator 5 being located in front of this engine unit 4. The engine unit 4 is a transversely disposed front engine with its crankshaft 6 extending transversely with respect to the travelling direction of the vehicle, thus, enabling to reduce the size of the engine compartment 1 and to enlarge the passenger compartment to render it spacious as much as possible. The crankshaft 6 of the engine 4 is journalled between a cylinder block 7 and a bearing case 8 connecting each piston 9, slidably received in the associated cylinder through a connecting rod 10 to the crankshaft 6. A cylinder head 11 is fixed to the cylinder block 7 and is provided with a head cover 12 and, each cylinder is provided with an ignition plug 13 in a usual manner. As shown in Figures 3 and 6 in double-dotted chain lines the crankshaft 6 at one end projecting out of the cylinder block 7 supports a disc 90 having projections 90a along its periphery in order to detect the phase of the crankshaft rotation (crank angle) by sensing the revolution of the projection 90a mounted on the disc 90 through a crank sensor 91 mounted on the cylinder block 7. The bearing case or crankcase 8 is provided with an oil pan 14 connected to an oil tank 15 which is disposed facing the front of the vehicle and extending from the bottom to the top of the internal combustion engine substantially through the entire height of the engine. As indicated above and depicted in the drawings the internal combustion engine is shown to be an in-line, six cylinder four cycle type engine, said individual cylinders forming a cylinder bank which is inclined backwards with respect to a vertical plane as the cylinder bore axis of the cylinders define a plane that is inclined rearwardly from the vertical. Said inclination, is specifically shown in Figures 1, 3 and 5 of the present application. In order to transmit the output power of the engine to the main driven wheels via a clutch mechanism 46 and a transmission 47, an engine output shaft 16 transmitting the output power of the engine, is disposed at the side of and in parallel to the crankshaft 6 and, is disposed slantly forwardly above the crankshaft 6 as specifically shown in Figures 1, 3 and 5. The disposal of the output shaft 16 with respect to the location of the crankshaft 6 is chosen such that a plane including both the axis of the crankshaft 6 and the axis of the output shaft 16 intersects with another plane defined by the cylinder axis at an acute angle α. (See Figure 5). In this way, the engine unit 4 can be compacted to a V-shape of its main axes with the vertex being determined through the low positioned cam shaft 6. The oil tank 15 is disposed slantly forwardly beneath or in front of the plane (crankshaft-output shaft) enabling an increased surface of the oil tank to face the front of the vehicle to be disposed to the cooling air flow when the vehicle moves forward (see Figure 4, Figure 5, Figure 3 and Figure 1). In this way, by means of positioning the output shaft 16 in such a manner that the angle α formed between the plane of the cylinder axes and the plane defined by the axis of the crankshaft 6 and the output shaft 16, is an acute angle, the distance between the output shaft 16 and the front wheel shafts 2 can be reduced in longitudinal direction of the vehicle. Also the position of the output shaft 16 with respect to the crankshaft position may vary from those shown in the Figures. Accordingly, the dimension of the vehicle compartment in longitudinal direction of the vehicle can be shortened allowing to achieve a spacious passenger compartment without increasing the overall length of the vehicle. As shown in Figure 5, the oil pan 14 has a pair of oil passages 17 extending substantially vertically through both sides of a guide portion 14a and, through each of the passages 17 oil is sucked in through an inlet port 17a at the bottom of the oil passage 17 by oil pumps 18 and 19 disposed on the output shaft 16 (Figure 6). The oil pan 14 and the oil tank 15 are partitioned by a wall provided with said oil passages 17. After having lubricated various portions of the engine the oil is collected at the bottom of the crank chamber A, formed with the cylinder block 7, the bearing case 8 and the oil pan 14. The inlet port 17a is provided with a net or sieve structure 20 so that dust or foreign material is prevented from entering into the oil passages 17 and cannot be sucked in. In order to avoid oil splashing through the cam shaft rotation causing a power loss of the cam shaft 6 during rotation, a plate 21 is mounted inside the oil pan 14 on a guide portion 14a. The oil pumps 18 and 19 are adapted to feed the oil through an oil cooler 22 and a filter 23 (Figure 4) and the oil reserved in the oil tank 15 is sucked through a strainer 25 disposed at the bottom of the oil tank 15 and, a pipe 26 extending from the strainer 25 upwardly and is fed to various lubricating points spread inside the engine by another oil pump 24 provided on the output shaft 16 of the engine (Figure 6). The flow of oil is shown by arrows in Figure 5. The oil tank 15 at its top, is provided with an oil refill mouth 15a closed by a refill cap 27 and, moreover, is provided with a breather portion 15b forming a labyrinth through partitions (not shown) so that oil may not leak out through the oil refill mouth 15a. The new location of the oil tank 15 to extend more vertically, as a result of the compacted engine structure, disposes the output shaft 16 closer to the cylinder block 7, rendering the top wall of the oil tank 15 through which the oil refill mouth 15a extends or is bored to be approximately horizontal. Thus, an oil refill operation through said oil refill mouth 15a is easier to perform than a refill operation through a conventional port provided through the head cover. As is shown in Figure 6, the output shaft 16 is driven by the crankshaft 6 through a gear transmission with a gear 28 mounted on the crankshaft 6 being in mesh, with a gear 29 mounted on the output shaft 16. The diameter and number of teeth of the gears 28, 29 is selected such, that a reduction gear ratio is obtained to slightly slow down the speed of the output shaft 16. As can also be derived from Figure 1, a gear 30 mounted on the output shaft 16 is connectd to a gear 32 on a countershaft 31, journalled by the cylinder head 11, through a first chain 33 and a gear 34 mounted on said countershaft 31 is connected to gears 38 on cam shaft 37 of the valve operating mechanism 36, through a second drive chain 35 so that the cam shafts 37 are rotated by the revolution of the crankshaft 6. The cams 39 are rotated together with their cam shafts 37 and operate the intake and exhaust valves (not shown) with predetermined timings. As indicated through Figures 1 to 5 the cylinder head 11 comprises exhaust pipes 40 and intake pipes 41 connected to each of the cylinders. Each intake pipe 41 is connected to a surge tank 42 which extends transversely and substantially in parallel to the cylinder block 7 supported therein through stays 43 (see Figures 2 to 4). The surge tank 42 is provided with a throttle valve 44 at its inlet end side and tapers from the upstream to the downstream side so that its cross-sectional area gradually reduces in order to increase the air flow speed of the intake air flowing from the upstream to the downstream side of the surge tank. Moreover, the farther the respective intake pipe 41 is positioned from the inlet end of the surge tank 42, the smoother is said air intake pipe 41 connected to said surge tank 42, i.e. the angle of connection of each intake pipe 41 to the surge tank 42 varies over the length of the surge tank in direction of the downstream flow of the intake air, so that air may be evenly supplied to each of the cylinders through the respective associated intake pipe 41. In the drawings, the surge tank 42 is positioned above the oil tank 15 (Figure 1, Figure 3, Figure 5), but it may also be positioned above the output shaft 16 as shown in phantom in Figure 5 or may extend above the oil tank 15. The output shaft 16 is provided with a fly wheel 45 and a clutch mechanism (not shown) at one end to transmit the engine power to the front wheel shafts 2 and the front wheels 3 through a transmission 47. By means of installing the fly wheel 45 and the clutch mechanism on the output shaft 16, the engine height can be reduced as compared with usual cases comprised in their art, where the fly wheel and the clutch mechanism are installed directly on the crankshaft 6. The transmission 47 with its primary and secondary sides disposed on the output shaft 16 and on the countershaft 48, respectively, drives the front wheel shafts 2 through a gear 49 mounted on the wheel shaft 2. By means of the steeply inclined plane L2 to form an acute angle with the plane L1, the distance between the front wheel shafts 2 supporting the final drive gear 49 affixed thereto and the output shaft 16 becomes shorter enabling to reduce the pitch circle diameter of the final gear 49 considerably. Accordingly, the engine weight can be remarkably reduced. By means of reducing the final diameter of the gear, moreover, the distance in between the engine to the ground can be increased, as, normally, said distance substantially depends on said final gear diameter. With conventional engines usually the auxiliaries, such as alternator, power steering pump, air compressor or the like, are driven by an accessory drive pulley which is located at one end of the crankshaft. This, however, results in an undesirable increase of the overall length of the engine. In order to reduce the overall length of the engine, the present invention sets out the accessory drive pulley 50 to be disposed on one end of the output shaft 16 or at an intermediate position thereof opposite to a bearing of the crankshaft 6 so as not to add anything to the overall length of the engine which is determined through the length of the crankshaft. In order to acquire said effects, a concave 51a is provided at the cylinder 7 and/or the associated portion of the crankcase 8 opposite to the main end bearing of the crankshaft 6 and the outer periphery of the pulley 50 is positioned such that it enters said concave 51 accordingly. The output shaft bearing for rotatably supporting the end of the output shaft 16 inwardly adjacent to the accessory drive pulley 50 is not shown in detail, but, is only indicated diagramatically by two opposite arrows. As shown in Figures 3 and 6 on the other end of the output shaft 16 opposite to the fly wheel 45, an auxiliary or accessory drive pulley 50 is positioned laterally opposite to a crankshaft main bearing 60 provided at one end of the cylinder block 7 and, similarly laterally opposite to a corresponding crankshaft bearing (not shown) provided on the bearing crankcase 8. The crankshaft end bearing 60 comprises the concave 51a formed at the position laterally opposite to the accessory drive pulley 50 and adapted to accommodate the associated portion of the accessory drive pulley 50. Normally, since the crankshaft 6 is journalled by the cylinder block 7 and the bearing case 8, there is a fear that the crankshaft web could interfere with the concave if said concave would simply be provided somewhere along the crankshaft axis. According to the present invention, the concave 51a is formed at a bearing 60, 61, either at an end portion or a spaced intermediate section of the crankshaft supporting structure. Thus, interference in between a crankshaft web and the concave 51a, 51b is avoided and thus, the distance L between the output shaft 16 and the crankshaft 6 (Figure 6) can be reduced. Accordingly, while the engine width can be reduced in a direction tranverse to the crankshaft 6 the output shaft 16 and the accessory drive pulley 50, can be disposed without protruding from the end of the crankshaft 6. The accessory drive arrangement is specifically shown in Figure 3 indicating a belt 55 to be wound around the pulley 50 and auxiliary pulleys for accessories such as an alternator 52, a power steering pump 53 and an air compressor 54 to drive them synchronously by the revolution of the output shaft 16. The tension of this belt 55 is adjusted through the idler 92. From Figure 3, the compacted layout of the engine unit 4 leading to a compacted accessory drive assembly as well, is clearly derivable. As shown in Figure 4, the oil tank 15 and the afore-mentioned accessory devices such as alternator 52, power steering pump 53 and air compressor 54 are disposed in front of the cylinder bank and, in addition, on one or the other side of the engine. So that an improved weight balance of the engine in direction of the crankshaft 6 may be obtained. Moreover, since the oil pump 15 and the auxiliary devices, such as alternator 52, power steering pump 53 and air compressor 54 can be disposed without overlapping with each other in the width direction of the engine (longitudinal direction of the vehicle) the width of the engine in the longitudinal direction of the vehicle can be reduced rendering the engine compact. Moreover, as said accessory devices 52, 53 and 54 are disposed facing the front of the vehicle and, as an external machinery driven by the output of the output shaft 16 through the crankshaft 6, are exposed to the travelling wind when the vehicle rides, all said auxiliary devices can be efficiently cooled. Finally, it should be noted, that a water inlet port 7a and a water outlet port 7b (Figure 4) are formed on the front surface of the cylinder block 7 facing the front of the vehicle and adapted to supply the cooling water to a radiator 5 through the water outlet port 7a and, to return it from the radiator 5 to a water pump through the water inlet port 7b tubing, to connect the radiator 5 to the cylinder block, is facilitated and cooling efficiency is improved. As shown in Figures 3 and 6, mainly, the accessory drive pulley 50 is located laterally opposite to the main end bearing 60 provided for the crankshaft 6 at one end of the cylinder block 7 and/or the bearing case 8 and the drive belt 55 can easily be dismounted for maintenance purposes. Thus, maintenance is facilitated. Of course, the position of the belt 55 is not limited to this place but, the accessory drive pulley 50 may be located at an intermediate position laterally opposite an intermediate main bearing 61 of the crankcase as is shown in double-dotted chain lines in Figure 6. Thus, the accessory drive pulley 50 is laterally opposite to a bearing 61 formed within the cylinder block 7 and/or a corresponding bearing (not shown) made up on the bearing case 8. The accessory drive pulley 50, again is partially accommodated through a concave 51b formed at the position of the bearing 61 in order to accommodate the accessory drive pulley 50 therein. Although the concaves 51 and 50b are formed at the position of bearings 60, 61 formed on both, the cylinder block 7 and the bearing case 8, they could be formed associated to a bearing formed only on either of both elements 7, 8 depending on the respective shape of the cylinder block 7 or the bearing case 8. Moreover, the provision of a concave is not limited to be recessed on the cylinder block 7 or the bearing case 8, but, can be formed at any member journalling the crankshaft 6. Finally, other types of engines wherein an oil pan is directly fastened to the cylinder block structure could also be used. In that case, the concave is also provided on said oil pan. Accordingly, the present invention, advantageously provides an automotive internal combustion engine having an output shaft extending in parallel to the crankshaft of the engine with an accessory drive pulley mounted on the output shaft. According to the present invention the accessory drive pulley is located laterally opposite to a bearing of the crankshaft. Preferably, the drive pulley is accommodated within a concave formed at the position of the bearing opposite to the accessory drive pulley. By means of that measure, the distance between the crankshaft 6 and the output shaft 16 can be reduced resulting in a reduced engine width transverse to the crankshaft and, moreover, the accessory drive pulley can be disposed within the extent of the crankshaft resulting in the length of the engine in the direction of the crankshaft axis being reduced, thus leading to a considerably compact engine design.

Claims: An internal combustion engine for automotive vehicles comprising a cylinder block (7) and a bearing case (8) supporting a crankshaft (6), an output shaft (16) disposed in parallel with the crankshaft (6) and supporting an accessory drive pulley (50) adapted to drive accessory devices, wherein the accessory drive pulley (50) is at least partially accommodated through a concave (51a,51b) formed into an outer surface of the cylinder block (7) and/or the bearing case (8), said outer surface extending substantially in parallel to the crankshaft (6) and said concave (51a,51b) is formed at a position of a crankshaft bearing (60,61) which is opposite to said auxiliary drive pulley (50). An internal combustion engine as claimed in Claim 1, characterized in that said concave (51b) is formed on a crankshaft supporting member journalling said crankshaft (6). An internal combustion engine as claimed in Claims 1 or 2, characterized in that the accessory drive pulley (50) is disposed at the end of the output shaft (16) engaging said concave (51a). An automotive internal combustion engine as claimed in Claim 1, characterized in that the accessory drive pulley (50) is disposed laterally opposite to an intermediate main bearing (61) of the crankshaft (6) engaging a concave (51b) which is formed on said cylinder block (7) and said bearing case (8), thus disposing the accessory drive pulley (50) within the extent of the crankshaft or the overall length of the cylinder block (7), respectively, without increasing the engine width perpendicularly to the crankshaft axis. An internal combusion engine as claimed in any of the preceding Claims 1 to 4, characterized in that the output shaft (16) is disposed slightly forwardly above the crankshaft (6) in such a manner that a plane (L2), including both the axis of the crankshaft (6) and the axis of the output shaft (16), intersects at an acute angle a plane (L1) including the axes of a plurality of cylinders of a cylinder bank.

Inventors: KOBAYASHI MANABU, OKUI KAORU, KOBAYASHI, MANABU, OKUI, KAORU
Applicants: YAMAHA MOTOR CO LTD, YAMAHA HATSUDOKI KABUSHIKI KAISHA
Application year: 1990
Main classification: F02B67
IPC codes: F02F1, F01M1, F02B1, F02B75, F02B61, F02B67