BACKGROUND OF THE INVENTION 0001 1. Field of the Invention 0002 The present invention relates to an outboard engine provided with an internal combustion engine having a throttle valve device capable of being easily operated from outside the outboard engine and of being neatly arranged inside an engine cover covering the internal combustion engine. 0003 2. Description of the Related Art 0004 A prior art outboard engine provided with an internal combustion engine and a throttle valve device combined with the internal combustion engine, and disclosed in JP 8-91297 A uses a push-pull cable, namely, a Bowden cable, for transmitting a throttle operating force to a driven part of the throttle valve device. 0005 In the outboard engine disclosed in JP 8-91297 A, the inner cable of the Bowden cable is connected to a control lever disposed in a front part of the outboard engine, another cable is extended between a drive pulley combined with the control lever, and a driven pulley combined with the throttle valve device disposed in a rear part of the outboard engine. The inner cable of the Bowden cable is moved relative to the outer cable of the Bowden cable to turn the driven pulley in a desired direction for opening or closing the throttle valve device by the drive pulley. 0006 Since the drive and the driven pulley respectively having certain diameters are used for transmitting the sliding motion of the inner cable of the Bowden cable to the valve shaft of the throttle valve device, a comparatively large space available for placing the drive and the driven pulley must be formed around the throttle valve device and hence the size of the engine cover needs to be increased. 0007 In most conventional outboard engines, a vertical internal combustion engine is disposed with its crankshaft extended in a vertical position in a front part of the outboard engines, an intake duct connected to the intake port of the internal combustion engine is extended on the right or the left side of the internal combustion engine, and the intake duct and a throttle valve device connected to the intake duct are placed inside an engine cover covering the internal combustion engine. In the following description, terms qualifying directions and sides, such as right, left, front, rear, longitudinal and lateral, are used to qualify directions and sides with respect to the advancing direction of a ship provided with the outboard engine. 0008 In most cases, a valve shaft holding the throttle valve of the throttle valve device is vertically extended, a throttle lever for turning the throttle valve has a base part connected to the upper or the lower end of the valve shaft and a free end connected directly or through links to an operating member, such as a push-pull wire. 0009 In the outboard engine of this type, the valve shaft is supported in an upper bearing part and a lower bearing part, and water collects in the lower bearing part and, in some case, the water collected in the lower bearing part hinders the light operation of the throttle valve device. 0010 An outboard engine disclosed in JP 11-34985 A is provided with a throttle valve device having a throttle valve supported on a valve shaft, and placed in an intake duct with the valve shaft extended in a horizontal position. 0011 In the outboard engine disclosed in JP 11-34985 A, a throttle lever connected to the valve shaft supporting the throttle valve, and a link connecting the throttle lever to a push-pull wire are arranged outside the intake duct, and a throttle position sensor for measuring the angular position of the throttle valve is connected to an outer end, lying outside the intake duct, of a shaft supporting a turning lever connecting the throttle lever and the push-pull wire. When the throttle lever, the link and the throttle position sensor are arranged outside the intake duct, the engine cover covering the internal engine of the outboard engine needs to be bulged and makes it difficult to form the outboard engine in compact construction. 0012 The present invention has been made in view of the foregoing problems and it is therefore an object of the present invention to provide an outboard engine provided with a throttle valve device requiring a small space for installation, and a small engine cover that does not need to be bulged.

SUMMARY OF THE INVENTION 0013 An outboard engine in a first aspect of the present invention includes: an internal combustion engine; a throttle valve device for controlling intake air to be taken in by the internal combustion engine; a driven unit combined with the throttle valve device; a drive unit for producing a throttle-driving force corresponding to an external throttle-operating force applied thereto; and a throttle valve operating mechanism for transmitting the throttle-operating force of the drive unit to the driven unit; wherein the throttle valve operating mechanism is a linkage including a plurality of component members, and the plurality of component members are joined by ball-and-socket joints. 0014 In the outboard engine according to the present invention, the driven unit combined with the throttle valve device, and the drive unit capable of producing the throttle-operating force are interlocked by the throttle valve operating mechanism, and the throttle-operating mechanism is the linkage. Therefore, the throttle-operating force of the drive unit can be smoothly transmitted to the driven unit regardless of the distance between the drive unit and the driven unit. 0015 Since the throttle-operating mechanism is a linkage, the throttle-operating force of the drive unit can be surely transmitted to the driven unit. 0016 Since the throttle operating mechanism is a linkage, and the links of the linkage are joined by the ball-and-screw joints, respectively, the throttle-operating force of the drive unit can be surely transmitted to the driven unit regardless of the positional relation between the driven unit and the drive unit, and regardless of the difference between a direction in which the throttle-operating force of the drive unit acts and a direction from which the driven unit receives the throttle-operating force. 0017 Preferably, the throttle valve device is disposed with the valve shaft inclined to a horizontal plane. The throttle valve device may be disposed such that the valve shaft slopes down from its front end toward its rear end. 0018 When the throttle valve device is disposed in the foregoing position, collection of water in bearing parts supporting the valve shaft can be prevented and the throttle valve device can be lightly operated. 0019 Preferably, the linkage includes the throttle valve device is disposed such that the valve shaft slopes down from a front end thereof toward its rear end. 0020 Preferably, the linkage includes a swing arm pivotally supported so as to be turned by the throttle-operating force of the drive unit, a bell crank, a link connecting the swing arm to the bell crank to transmit the swing motion of the swing arm to the bell crank, and a connecting rod for transmitting motions of the bell crank to the driven unit. 0021 Preferably, the arm, the bell crank and the link are supported on a single bracket. 0022 Preferably, a connecting rod for transmitting the throttle-operating force of the drive unit to the arm is longitudinally extended, and the connecting rod for transmitting the motion of the bell crank to the driven unit is laterally extended. 0023 Joints joining adjacent joining parts of the arm, the bell crank, the link and the two connecting rods may be ball-and-socket joints, respectively. 0024 An outboard engine in a second aspect of the present invention includes: an internal combustion engine, an engine cover covering the internal combustion engine; and a throttle valve device disposed inside the engine cover and provided with a throttle valve for controlling intake air to be taken in by the internal combustion engine; wherein the throttle valve is supported on a valve shaft, a driven unit to be driven by an external throttle-operating force is combined with one end of the valve shaft, a throttle position sensor is combined with the other end of the valve shaft, and the valve shaft is inclined to a horizontal plane. 0025 In this outboard engine, a dimension of the throttle valve along the valve shaft is small and the throttle valve device is compact and can be neatly disposed inside the engine cover. 0026 Since the valve shaft of the throttle valve is inclined at a small angle to a horizontal plane, collection of water in bearing parts supporting the valve shaft can be prevented and the throttle valve device can be lightly operated. 0027 The driven unit and the throttle position sensor combined with the opposite ends of the inclined valve shaft of the throttle valve can be inclined so as to be substantially parallel to the inclined surfaces and curved surfaces of the engine cover and can be disposed close to the engine cover covering the internal combustion engine. Consequently, the internal combustion engine can be neatly disposed inside the engine cover. 0028 Preferably, the internal combustion engine has a crankshaft disposed in a crankcase on the front side of the center of the outboard engine with respect to the longitudinal direction, and the throttle valve device is disposed in front of the crankcase, and the valve shaft is extended along a longitudinal surface of the outboard engine. 0029 Thus, the intake duct having one end connected to intake ports formed in a cylinder head on the rear side can be extended along either the right or the left side surface of the internal combustion engine and around the front side of the crankcase. Therefore, the engine cover does not need to be bulged, the intake duct can be formed in a long length, the outboard engine can be formed in compact construction, and intake efficiency can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS 0030 FIG. 1 is a side elevation of an outboard engine in a preferred embodiment according to the present invention taken from the right side of the outboard engine; 0031 FIG. 2 is a partly cutaway plan view of the outboard engine shown in FIG. 1; 0032 FIG. 3 is an enlarged plan view of an essential part of the outboard engine shown in FIG. 1; 0033 FIG. 4 is a fragmentary, longitudinal sectional view taken on the line IV-IV in FIG. 1; 0034 FIG. 5 is a view taken in the direction of the arrow V in FIG. 2; 0035 FIG. 6 is an exploded perspective view of a throttle-operating mechanism; 0036 FIG. 7 is a perspective view of the throttle-operating mechanism shown in FIG. 6; 0037 FIG. 8 is a plan view of a link; 0038 FIG. 9 is a plan view of the link shown in FIG. 8; 0039 FIG. 10 is a cross-sectional view taken on the line X-X in FIG. 8; 0040 FIG. 11 is a cross-sectional view taken on the line IX-IX in FIG. 8; and 0041 FIG. 12 is a plan view of a joint for a connecting rod.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 0042 The construction of an outboard engine 1 in a preferred embodiment of the present invention shown in FIGS. 1 to 12 will be described. 0043 The front side of the outboard engine 1 on the side of a ship, i.e., the right side as viewed in FIG. 1, is supported by a support device 3 on the transom 2 of the ship. The outboard engine 1 has an extension case 4 covering a lower part of the outboard engine 1, an under cover 5 joined to the upper end of the extension case 4, and an engine cover 6 detachably joined to the upper end of the under cover 5. The engine cover 6 has an air intake opening 6a. A gear case 7 is joined to the lower end of the extension case 4. A propeller P extends rearward from the gear case 7. 0044 An expanded upper part of the under cover 5 and the engine cover 6 define an engine chamber 8. An inline four-cylinder four-stoke-cycle internal combustion engine 10 and auxiliary machines are placed in the engine chamber 8. The internal combustion engine 10 is disposed with its crankshaft 9 extended in a vertical position. As shown in FIG. 4, a flywheel 9a is mounted on the lower end of the crankshaft 9. 0045 Referring to FIG. 1, the internal combustion engine 10 has a crankcase 11, a cylinder block 12 and a cylinder head arranged in that order rearward and joined together. The crankshaft 9 is supported for rotation between the joining surfaces of the crankcase 11 and the cylinder block 12. The cylinder block 12 is provided with four cylinders 14 in a vertical arrangement. As shown in FIG. 2, pistons 15 are fitted in the cylinders 14 for longitudinal, sliding reciprocation, and are connected to the crankshaft 9 by connecting rods 16 (FIG. 4) to drive the crankshaft 9 for rotation. 0046 As shown in FIG. 2, ignition plugs, not shown, are attached to the cylinder head 13 so as to be exposed to combustion chambers 17 defined by the cylinders 14, the pistons 15 and the cylinder head 13, respectively. An intake port 18 and an exhaust port 19 for each of the cylinders 14 are formed in a lateral arrangement in the cylinder head 13 so as to open into the combustion chamber 17. An intake valve 20 and an exhaust valve 21 are seated on the inner open ends, on the side of the combustion chamber 17, of the intake port 18 and the exhaust port 19 of each cylinder 14, respectively. A fuel injection valve, not shown, is placed in the intake port 18. The intake valves 20 and the exhaust valves 21 are opened and closed by valve trains, not shown. 0047 An intake vessel 22 defining an intake chamber is disposed in an upper right-hand region (a right region in FIG. 2) of a front part of the engine chamber 8. The inlet ends (right ends in FIG. 2) of the intake ports 18 are connected through an intake manifold 23 and a throttle valve device 34 to the intake box 22. A fuel injector i is provided at the downstream end of the intake manifold 23. The intake box 22 is opened through an intake duct 33 into the atmosphere as shown in FIG. 4. 0048 The support device 3 has a main support 24 including a swivel case 25. A shaft, not shown, attached to a mount frame is supported for turning in a horizontal plane on the swivel case 25. An upper mount frame 26 of the mount frame is connected to a mount case 30 formed integrally with a lower part of the internal combustion engine 10 by an upper mount rubber 28. A lower mount frame 27 of the mount frame is attached to the extension case 4 by a lower mount rubber 29. A steering arm 31 formed in the mount frame is turned in a horizontal plane to turn the outboard engine 1 laterally for steering on the swivel case 25. 0049 The main support 24 is supported on the transom 2 by a horizontal tilt shaft 32 and can be turned in a vertical plane on the tilt shaft 32. 0050 Referring to FIGS. 2 and 3, the throttle valve device 34 has a cylindrical valve case 35, and a longitudinal valve shaft 36 supported for turning on the valve case 35. The valve shaft 36 is slightly inclined at an angle (FIG. 4) to a horizontal plane such that its front end is at a level higher than that of its rear end. The throttle valve device 34 has a disk-shaped valve element 37 attached to the valve shaft 36, an operating lever 38 supported for turning on a rear part of the valve case 35, and an interlocking mechanism 39 interlocking the valve shaft 36 and the operating lever 38. The interlocking mechanism 39 turns the valve shaft 36 such that a turning angle through which the operating lever 38 needs to be turned to turn the valve element 37 through a unit angle when the valve element 37 is near its fully closed position is greater than a turning angle through which the operating lever 38 needs to be turned to turn the valve element 37 through the same unit angle when the valve element 37 is near its fully open position. A throttle position sensor 57 is disposed on a front part of the valve case 35. The front end of the valve shaft 36 is connected to a movable member 57a of the throttle position sensor 57. 0051 Although the interlocking mechanism 39 in this embodiment is a cam mechanism, the interlocking mechanism 39 may be any suitable mechanism, such as a linkage or an elliptic-gear mechanism, provided that the mechanism has the same characteristics as the interlocking mechanism 39. 0052 A throttle valve operating mechanism 40 for operating the throttle valve device 34 will be described. 0053 Referring to FIG. 5, the operating lever 38 of the throttle valve device 34 is provided at its free end with a ball-ended connecting member 38a. The ball-ended connecting member 38a deviates from a shaft 38b on which the operating lever turns. The ball of the ball-ended connecting member 38a is engaged in a socket 41a of a socket-ended connecting member 41 provided with an internally threaded hole 41b (FIG. 12). The ball of the ball-ended connecting member 38a and the socket 41a constitute a ball-and-socket joint. A externally threaded part 42a of a rod 42 is screwed in the internally threaded hole 41b, and a locknut 43 put on the externally threaded part 42a is screwed down firmly against the end of the socket-ended connecting member 41 to connect the socket-ended connecting member 41 securely to the left end of the rod 42. The socket-ended connecting member 41 is able to turn in all planes passing the center of the ball of the ball-ended connecting member 38a attached to the free end of the operating lever 38. As shown in FIGS. 2 and 3, a socket-ended connecting member 58 similar to the socket-ended connecting member 41 is attached to the right end of the rod 42. 0054 Referring to FIGS. 3 and 6, a bracket 44 is fastened to the right side wall of the crankcase 11 of the internal combustion engine 10 with a bolt 45 passed through a through hole 44a formed in the bracket 45. A pivot shaft 46a supporting a bell crank 46 is supported for rotation in bearings 47 in a vertical hole 44b formed in the bracket 44. A washer 48 is put on a lower end part of the pivot shaft 46a, and a snap ring 49 is engaged in an annular groove 46b formed in a lower part of the pivot shaft 46a to retain the bell crank 46 on the bracket 44. A ball-ended connecting member 46d is attached to the front arm 46c of the bell crank 46 so as to extend upward. A ball-ended connecting member 46f is attached to the rear arm 46e of the bell crank 46 so as to extend downward. The ball-ended connecting member 46d attached to the front arm 46c of the bell crank 46 is engaged in the socket of the socket-ended connecting member attached to the right end of the rod 42. The ball-ended connecting member 46d and the socket-ended connecting member 58 constitute a ball-and-socket joint. 0055 Referring to FIGS. 8 to 11, a front end part 50a of a link 50 has substantially horizontal, parallel, flat upper and lower surfaces, and is provided with a socket 50b. The ball-ended connecting member 47f attached to the rear arm 46e of the bell crank 46 is engaged in the socket 50b of the link 50. A hole 50c is formed in a part of the link 50 on the front side of the socket 50b. The sockets 50b and 50c are connected by a slit 50d. A rear end part 503 of the link 50 has parallel right and left flat surfaces extending substantially along front and rear vertical planes. A socket 50f, a hole 50g and a slit 50h similar to those formed in the front end part 50a are formed in the rear end part 50e. The ball-ended connecting member 46f attached to the rear arm 46e of the bell crank 46 is engaged in the socket 50b of the front end part 50a of the link 50 so form a ball-and-socket joint. 0056 As shown in FIG. 6, a pivot shaft 44c projects rightward from a part, near the through hole 44a and the vertical hole 44b, of the bracket 44. An arm 51 is provided in the left side surface of a base part thereof with a cylindrical recess, not shown. The pivot shaft 44c of the bracket 44 is fitted in the cylindrical recess of the arm 51 to support the arm 51 for forward and backward turning. A holding bolt 52 passed through a through hole 51a formed coaxially with the cylindrical recess in the base part of the arm 51 is screwed in a center threaded hole 44d formed in the support shaft 44c of the bracket 44 to hold the arm 51 on the support shaft 44c. A ball-ended connecting member 51b is attached to a middle part of the right side surface of the arm 51 so as to project rightward. The ball-ended connecting member 51b is engaged in the socket 50f of the rear end part 50e of the link 50 to form a ball-and-socket joint. A washer 53 is loosely put on the holding bolt 52. 0057 A connecting pin 54 is attached to the lower end of the arm 51 so as to rightward from the arm 51. A connecting member 70 is swingably mounted on a free end part of the connecting pin 54. 0058 As shown in FIG. 2, a box 59 containing electrical equipment is disposed at a position above the right-hand side (on the left side as viewed in FIG. 2) of the internal combustion engine 10. 0059 As shown in FIG. 3, a throttle operating Bowden cable 60 is connected to the throttle valve operating mechanism 40 to operate the throttle valve device 34. The throttle operating Bowden cable 60 has a flexible cable 61 for transmitting operating force applied to an operating handle placed in a ship, not shown, to the throttle valve operating mechanism 40, and a case 62 enclosing the cable 61. A bracket 55 for holding the throttle operating Bowden cable 60 is attached to the under cover 5 in a right part of the engine chamber 8. A holding pipe 63 having a neck 63a is put on a rear end part of the case 62, and the neck 63a is forced into a slot 55b formed in a standing part 55a of the bracket 55 to hold case 62 of the throttle operating Bowden cable 60 on the bracket 55. 0060 A metal guide pipe 64 is connected to the rear end of the holding pipe 63. The joint of the holding pipe 63 and the guide pipe 64 is covered with a sealing member 65. The rear end 61a of the cable 61 is connected to the front end 66a of a connecting rod 66 in the guide pipe 64. The connecting rod 66 extends rearward from the guide pipe 64. A rear end part of the guide pipe 64 is covered with a sealing member 67. An exposed part, extending forward from the under cover 5, of the throttle operating Bowden cable 60 is covered with a rubber grommet 56 fitted in an opening 5a formed in the under cover 5. 0061 Referring to FIG. 6, the connecting rod 66 has an externally threaded rear end part 66a. A locknut 68 is screwed on the externally threaded rear end part 66a. The externally threaded rear end 66a is screwed in an internally threaded hole 71a formed in a body 71 of the connecting member 70, and is fastened firmly to the connecting member 70. 0062 A sliding cover 72 is mounted on the body 71 of the connecting member 70. The sliding cover 72 is able to slide longitudinally in a predetermined range. The connecting pin 54 attached to the lower end of the arm 51 is inserted in a hole 71b formed in the body 71 of the connecting member 70, and a slot 72a formed in the sliding cover 72. When the connecting rod 66 is pulled forward, the sliding cover, 72 slides forward relative to the body 71 by a predetermined stroke and thereby the connecting pin 54 is pulled forward and the arm 51 is turned forward. When the connecting rod 66 is pushed rearward, the connecting pin 54 engaged in the hole 71b of the body 71 is moved rearward and thereby the arm 51 is turned rearward. 0063 Referring to FIG. 7, a shifting Bowden cable 69 for shifting a transmission is extended substantially parallel to the throttle operating Bowden cable 60 on the right side of the throttle operating Bowden cable 60. The shifting Bowden cable 69 is held on the standing part 55a of the bracket 55. When a crewman on board the ship pulls the throttle lever rearward to open the fully closed throttle valve device 34 of the outboard engine 1 embodying the present invention shown in FIGS. 1 to 12, the cable 61 of the throttle operating Bowden cable 60 is pulled forward. Consequently, the arm 51 having the lower end connected through the connecting member 70 and the connecting rod 66 to the rear end of the cable 61 is turned forward from a position shown in FIG. 4 through an angle of about 90 at a maximum to turn the bell crank 46 counterclockwise, as viewed in FIG. 3, through an angle of 90 at a maximum. Consequently, the connecting rod 42 is moved leftward (upward, as viewed in FIG. 3) to turn the operating lever 38 of the throttle valve device 34 counterclockwise, as viewed in FIG. 5, so that the fully closed throttle valve device 34 is opened. The angular position of the valve element 37 is measured by the throttle position sensor 57. 0064 When the operating lever 38 is turned through an angle in an opening direction with the throttle valve device 34 in a nearly fully closed state, the valve shaft 36 and the valve element 37 turn through a very small angle as compared with an angle through which the operating lever 38 is turned, owing to the agency of the interlocking mechanism 39 interlocking the valve shaft 36 and the operating lever 38. Thus, the fine adjustment of the opening of the throttle valve device 34 is possible. 0065 The cable 61 of the throttle operating Bowden cable 60 slides longitudinally, the rod 42 moves laterally to turn the operating lever 38 of the throttle valve device 34, and the operating lever 38 is connected to the connecting rod 66 connected to the rear end of the cable 61 of the throttle operating Bowden cable 60 by the throttle valve operating mechanism 40 including the connecting member 41, the rod 42, the bell crank 46, the link 50, the arm 51 and the connecting member 70. Therefore, even if the throttle valve device 34 is far off to the left from a rearward extension of the throttle operating Bowden cable 60, the operating force can be surely transmitted through the cable 61 to the operating lever 38 and the throttle valve device 34 can be smoothly opened and closed. 0066 Since the bracket 55 holding the throttle operating Bowden cable 60 is spaced a long distance apart from the arm 51, and the rear end part of the throttle operating Bowden cable 60 is held on the bracket 55, and the holding pipe 63 and the guide pipe 64 are easily tiltable, the cable 61 is able to slide smoothly in the case 62 and the connecting rod 66 is able to slide smoothly in the guide pipe 64 regardless of the vertical shifting of the connecting pin 54 attached to the lower end of the arm 51 even if the arm 51 is turned through a large angle and the connecting pin 54 of the arm 51 is shifted vertically by a long distance. 0067 Since the bell crank 46 can be freely turned in a three-dimensional space by the tilting motion of the operating lever 38 and the longitudinal turning of the arm 51, the swing motion of the arm 51 can be smoothly and surely transmitted to the operating lever 38. 0068 As shown in FIGS. 3 and 4, the operating lever 38, i.e., a driven member of the throttle valve device 34, is disposed at the rear end of the throttle valve device 34, and the throttle position sensor 57 is disposed in front of the throttle valve device 34. Therefore, the valve shaft 36 of the throttle valve device 34 is short, and hence the throttle valve device 34 can be neatly disposed in the space defined by the engine cover 6 covering the internal combustion engine 10. 0069 As shown in FIG. 4, the valve shaft 36 of the throttle valve device 34 is slightly inclined to a horizontal plane. Therefore, water does not collect in the bearing parts in which the valve shaft 36 of the throttle valve device 34 is supported and hence the throttle valve device 34 can be lightly operated. 0070 The valve shaft 36 is inclined at an angle to a horizontal plane such that its front end is at a level higher than that of its rear end. Therefore, the operating lever 38 does not come into contact with the crankcase 11 when the valve shaft 36 is turned by the throttle valve operating mechanism 40 even though the operating lever 38 is disposed close to the front surface of the crankcase 11 of the internal combustion engine 10. Since the front surface of the throttle position sensor 57 is substantially parallel to the front wall of the engine cover 6 and a narrow gap is formed between the throttle position sensor 57 and the engine cover 6, the internal combustion engine 10 and the throttle valve device 34 can be neatly arranged inside the engine cover 6. 0071 In the outboard engine 1 having the crankcase 11 disposed in the front part thereof and the cylinder head 13 disposed in the rear part thereof, the throttle valve device 34 is disposed in front of the crankcase 11, intake air flows from the left side (right side, as viewed in FIG. 2) of the outboard engine 1 through the throttle valve device 34 rightward, and the upstream end of the throttle valve device 34 is connected to the intake ports 18 formed in the cylinder head 13 by the intake manifold 23 as shown in FIG. 2. Therefore, the intake manifold can be formed in a very long length and hence the intake efficiency of the internal combustion engine 10 can be improved.