Engine device

Abstract: An engine device having an engine body (6) provided with a crankshaft (7) and balancer shafts (8,9) adapted to rotate in association with the crankshaft (7), with the engine body (6) covered with an engine cover (58), whereby engine auxiliary (70,80) is integrally incorporated in the engine cover (58).

Description: The present invention relates to an engine device according to the preamble part of the independent claim 1. An engine device has a structure in which engine auxiliaries, such as an oil pump or water pump are arranged as a unit at the front side of the engine unit and those auxiliaries are driven through timing chains or belts for engine auxiliaries. In such structures, the engine auxiliaries, such as an oil pump and water pump are incorporated in an engine body as a unit, resulting in increased number of components, complexity of assembly, increased cost or the like. It also tends to increase the number of locations to be sealed, resulting in the occurrence of leakage of oil or water. In addition, waste power is consumed in the bearings to support the load from tension force of timing chains or belts for engine auxiliaries. DE 41 28 432 A discloses a gear drive for a diesel combustion engine wherein the gear drive is arranged on a fly wheel side of the engine and a drive of an injection pump, cool water pump and oil pump has been carried out by different gears of the gear drive. It is an objective of the present invention to improve an engine device as indicated above so as to reduce a number of components of the auxiliaries to be incorporated and a number of locations to be sealed. The objective is solved according to the present invention by an engine device comprising the features of the independent claim 1. According to an embodiment, the engine auxiliary is coupled to the balancer shafts so that both the engine auxiliary and the balancer shafts are allowed to rotate together. According to this embodiment, since the engine auxiliary is coupled to the balancer shafts so that both the engine auxiliary and the balancer shafts are allowed to rotate together and the central-shaft-directly-driven-system is employed, it is possible to reduce the load applied on the bearings and to reduce the volume of the bearings. According to another embodiment, the balancer shafts are rotatably supported on the engine body, an end of the crankshaft is sealed with a sealing member, wherein a shaft of the engine auxiliary is rotatably supported through bearings, and the engine auxiliary and the balancer shafts are coupled to rotate together. According to the aforesaid embodiment, since the balancer shafts are rotatably supported on the engine body, the auxiliary is rotatably supported on the engine cover, the engine auxiliary and the balancer shafts are coupled to rotate together, and the central-shaft-directly-driven-system is employed, it is possible to reduce the load applied on the bearings and to reduce the volume of the bearings. Further, the positioning of the crankshaft relative to the auxiliary shaft is easily and accurately carried out as the end of the crankshaft is projected out of the engine cover and then sealed. According to a further embodiment, an engaging protrusion of the pump shaft is in engagement with an engaging recess formed on a tip of said balancer shaft and the balancer shaft and the pump shaft are coupled integrally rotatably. According to a further embodiment, the crankshaft is supported on bearings in a cylinder block forming the engine body, and a first of the balancer shafts is at one end portion rotatably supported by a needle bearing, whereas the other end portion is supported by a ball bearing. According to this embodiment, it is possible to reduce a load applied on the bearings and to reduce the volume of the bearings due to the employment of the central-shaft-directly-driven-system. According to a further embodiment, a second of the balancer shafts is at one end portion rotatably supported by a needle bearing, whereas the other end portion is rotatably supported by a ball bearing. Other preferred embodiments of the present invention are laid down in further dependent claims. In the following, the present invention is explained in greater detail with respect to several embodiments thereof in conjunction with the accompanying drawings, wherein: Fig. 1 is a side view of the front side part of the vehicle equipped with the engine device; Fig. 2 is a cross-sectional view of the engine device; Fig. 3 is a side view of the engine device; Fig. 4 is a side view illustrated with the engine cover being removed. Fig. 5 is a cross-sectional view of a water pump part according to another embodiment. In the front and side part of a vehicle 1, an engine room 3 is disposed in front of the front wheels 2, an engine 4 is equipped within the engine room 3, and a radiator 5 is located in the front side of the engine 4. This engine 4 is a 2-cylinder, 4-stroke engine and disposes an oil pan 700 at the bottom of an engine body 6. A crankshaft 7 is disposed within the engine body 6 along the vehicle's width direction, and balancer shafts 8, 9 are disposed in the front and rear side of the crankshaft along the width direction. In a cylinder head 10 configuring the engine body 6 are formed branch exhaust passages 11, 12 and branch intake passages 13, 14 for each cylinder. The branch exhaust passages 11, 12 are opened and closed by the corresponding exhaust valve 15 disposed in respectively, and the branch intake passages 13, 14 are opened and closed by the corresponding intake valve 16 disposed in respectively. The exhaust valve 15 and the intake valve 16 are driven by cams 19, 20 disposed on camshafts 17, 18. The branch exhaust passages 11., 12 are collected to a collected exhaust passage 21, which is connected to an exhaust pipe 22. The exhaust pipe 22 connected to each cylinder is collected to a collected exhaust pipe 23, which passes from the front-side of the engine body 6 through the underneath and extends rearward. In addition, to the exhaust pipe 23 is provided a catalyst 24. The branch intake passages 13, 14 are collected to a collected intake passage 25, in which a throttle body 26 is provided, wherein the collected intake passage 25 is connected to the cylinder head 10. The throttle body 26 has an intake passage 28 connecting to the intake passage 25 of each cylinder, and furthermore, an intake manifold 30 is connected to the throttle body 26. On the cylinder head 10, an injector 35 is disposed. To the throttle body 26 is provided a throttle valve 40 controlling the flow rate of the respective intake passage 28. This throttle valve 40 is controlled in accordance with information of the engine speed and the throttle openings. In a cylinder block 50 configuring the engine body 6, the crankshaft 7 is rotatably supported on bearings 50a. A balancer shaft 8 is arranged that one end portion 8a is rotatably supported through a needle bearing 51 and another end portion 8b is rotatably supported through a ball bearing 52. A balancer shaft 9 is also arranged in the same manner that one end portion 9a is rotatably supported through a needle bearing 53 and another end portion 9b is rotatably supported through a ball bearing 54. Each of the balancers 8, 9 is inserted from the end portion 8a, 9a of an opening 50b, 50c of the cylinder block 50 and assembled the ball bearing 52, 54 to the opening 50b, 50c. A gear 55 is mounted on the crankshaft 7, while gears 56 and 57 are mounted on the balancer shaft 8 and 9, respectively. The gears 56 and 57 respectively engage the gear 55. As the crankshaft 7 rotates, the balancer shafts 8 and 9 are interlocked to rotate together through gears 55, 56 and 57. One side of the cylinder block 50 is covered with an engine cover 58, so that the engine cover 58 forms a cam chain chamber 59. A cam gear 60 is disposed on the crankshaft 7, and a cam chain 61 is fitted over between the cam gear 60 and a gear disposed on the camshafts 17, 18 (not shown). The camshafts 17, 18 are interlocked to rotate by rotating of the crankshaft 7 through the cam chain 61, and the exhaust valve 15 and the intake valve 16 are opened and closed with the predetermined timing. An end portion 7a of the crankshaft 7 is protruded from an opening 58a of the engine . cover 58, and a driving pulley 62 is mounted on the protruding end portion 7a with a locking bolt 63. Between a shaft 62a of the driving pulley 62 and the opening 58a is sealed with sealing member 64. A driving belt 66 is fitted over between the driving pulley 62 and a air compressor 65 disposed on the front side of the engine, and a driving belt 68 is fitted over between the driving pulley 62 and an alternator 67 disposed on the rear side of the engine. An oil pump 70 and a water pump 80 are integrally incorporated in the engine cover 58. That is to say, the oil pump 70 is integrally formed so that a pump housing 71 is one part of the engine cover 58, and a pump chamber 73 is formed by assembling the pump housing 71 with a cover housing 72. A pump shaft 75 with blades 74 is rotatably supported between the pump housing 71 and the cover housing 72. An engaging protrusion 75a is formed on a tip of the pump shaft 75. An engaging recess 8c is formed on a tip of the balancer shaft 8 positioned opposite to the pump shaft 75. The engaging protrusion 75a of the pump shaft 75 is engaged with the engaging recess 8c of the balancer shaft 8, and the balancer shaft 8 and the pump shaft 75 are coupled integrally and rotatably. Oil is supplied to each part of the engine 4 by rotation of the pump shaft 75. However, it is also possible to only arrange the water pump 80 integrally with the engine cover 58. The water pump 80 is also formed integrally so that a pump housing 81 is one part of the engine cover 58, and a pump chamber 83 is formed by assembling the pump housing 81 with a cover housing 82. In the pump housing 81, a pump shaft 85 with blades 84 is rotatably supported through a ball bearing 86. An engaging protrusion 85a is formed on a tip of the pump shaft 85. An engaging recess 9c is formed on a tip of the balancer shaft 9 positioned opposite to the pump shaft 85. The engaging protrusion 85a of the pump shaft 85 is engaged with the engaging recess 9c of the balancer shaft 9, and the balancer shaft 9 and the pump shaft 85 are coupled integrally and rotatably. The pump housing 81 is protruded into the cam chain chamber 59, and it is configured to be due to the fact be small in size that the pump shaft 85 is sealed in this pump housing 81 with a mechanical sealing member 98 and an oil-sealing member 99. The mechanical sealing member 98 and the oil-sealing member 99 shut out the cooling water and oil, and a weep hole 81 a is formed between the mechanical sealing member 98 and the oil-sealing member 99. In the cover housing 82, a cooling water intake passage 90 is provided, and the cooling water from the radiator 5 is supplied to the pump chamber 83 through the cooling water intake passage 90. By driving of the water pump 80, the cooling water is supplied from a cooling water discharging passage 91 formed in the cover housing 82 and the engine cover 58 to each part of the engine. In the embodiment shown in Fig. 5, a cooling water passage 101 is formed in a cover housing 100 and is communicated with a thermostat 88 disposed in the engine cover 58. Cooling water supplied from the radiator 5 is passed through the thermostat 88 via connection pipe 89 and thereafter supplied to the pump chamber 83 through the cooling water passage 101. If the thermostat 88 is disposed at the cooling water inlet side in the engine cover 58 as in this embodiment, a thermostat housing 88a as part of the engine cover is formed together with the engine cover, resulting in the reduction of the number of components and the prevention of occurrence of vibration and water leakage which may be produced in case of the thermostat housing and the engine cover being separately formed. In this invention, since the balancer shafts 8, 9 are rotatably supported on the engine body 6, the auxiliary such as the oil pump 70, water pump 80 or the like is rotatably supported on the engine cover 58, the engine auxiliary and the balancer shafts 8, 9 are coupled to rotate together, and the central-shaft-directly-driven-system is employed, it is possible to reduce the load applied on the bearings and to reduce the volume of the bearings. Further, the positioning of the crankshaft relative to the auxiliary shafts is easily and accurately carried out as the end of the crankshaft is projected out of the engine cover and then sealed. Also, integral incorporation of the auxiliaries such as the oil pump 70 and water pump 80 into the engine cover 58 allows the reduction in the number of auxiliary components to be assembled, as well as the number of locations to be sealed. It is also allowed to reduce the number of components of the oil pump 70 and water pump 80 to be incorporated, to reduce the load applied on the bearings and to reduce in volume of the bearings due to the employment of the central-shaft-directly-driven-system. As shown and described, according to an engine device having an engine body provided with a crankshaft and balancer shafts adapted to rotate in association with the crankshaft, wherein the engine body is covered with an engine cover, engine auxiliary being an oil pump and/or a water pump is integrally incorporated in the engine cover, wherein the oil pump and/or the water pump are/is integrally formed so that a pump housing is one part of the engine cover, wherein said pump housing forms together with a cover housing a pump chamber, integral incorporation of the auxiliary into the engine cover allows the reduction in the number of auxiliary components to be assembled, as well as the number of locations to be sealed. According to an embodiment, since the engine auxiliary is coupled to the balancer shafts so that both the engine auxiliary and the balancer shafts are allowed to rotate together and the central-shaft-directly-driven-system is employed, it is possible to reduce the load applied on the bearings and to reduce the volume of the bearings. According to another embodiment, since the balancer shafts are rotatably supported on the engine body, the auxiliary is rotatably supported on the engine cover, the engine auxiliary and the balancer shafts are coupled to rotate together, and the central-shaft-directly-driven-system is employed, it is possible to reduce the load applied on the bearings and to reduce the volume of the bearings. Further, the positioning of the crankshaft relative to the auxiliary shafts is easily and accurately carried out as the end of the crankshaft is projected out of the engine cover and then sealed.

Claims: An engine device having an engine body (6) provided with a crankshaft (7) and balancer shafts (8,9) adapted to rotate in association with the crankshaft (7), wherein the engine body (6) is covered with an engine cover (58), and where an engine auxiliary (70,80) being an oil pump (70) and/or a water pump (80) is integrally incorporated in the engine cover (58), characterized in that the oil pump (70) and/or the water pump (80) are/is integrally formed so that a pump housing (71,81) is one part of the engine cover (58), wherein said pump housing (71,81) forms together with a cover housing (72,82) a pump chamber (73,83). An engine device according to claim 1, characterized in that the engine auxiliary (70,80) is coupled to the balancer shafts (8,9) so that both the engine auxiliary (70,80) and the balancer shafts (8,9) are allowed to rotate together. An engine device according to claim 1 or 2, characterized in that the balancer shafts (8,9) are rotatably supported on the engine body (6), an end of the crankshaft (7) is sealed with a sealing member (64), wherein a shaft (75,85) of the engine auxiliary (70,80) are rotatably supported through bearings (86), and the engine auxiliary (70,80) and the balancer shafts (8,9) are coupled to rotate together. An engine device according to at least one of the preceding claims 1 to 3, characterized in that an engaging protrusion (75a,85a) of the pump shaft (75,85) is in engagement with an engaging recess (8c,9c) formed on a tip of said balancer shaft (8,9) and the balancer shaft (8,9) and the pump shaft (75,85) are coupled integrally rotatably. An engine device according to at least one of the preceding claims 1 to 4, characterized in that the crankshaft (7) is supported on bearings (50a) in a cylinder block (50) forming the engine body (6), and that a first (8) of the balancer shafts (8,9) is at one end portion (8a) rotatably supported by a needle bearing (51), whereas the other end portion (8b) is supported by a ball bearing (52). An engine device according to at least one of the preceding claims 1 to 5, characterized in that a second (9) of the balancer shafts (8, 9) is at one end portion (9a) rotatably supported by a needle bearing (53), whereas the other end portion (9b) is rotatably supported by a ball bearing (54).

Inventors: YAMAGUCHI AKIRA, YAMASHITA NORIYUKI, YAMAGUCHI, AKIRA, YAMASHITA, NORIYUKI
Applicants: YAMAHA MOTOR CO LTD, YAMAHA HATSUDOKI KABUSHIKI KAISHA
Application year: 2000
Main classification: F02B67
IPC codes: F02B67, F01P5, F02B77, F01M1