Compressed-air supply system for vehicles

Abstract: A compressed-air supply system for vehicles comprises an air compressor (52) driven by an engine having at least one air intake valve and at least one exhaust valve operated by at least one camshaft (37). Said system further comprising an air pipe (60) connected to said air compressor (52) for supplying compressed air, whereby a first actuator (49) is provided communicating with said pipe being capable of generating an operational force based upon the compressed air to assist the shifting operation of a transmission device (48).

Description: The present invention relates to a compressed-air supply system for vehicles according to the preamble of claim 1. The drive transmission system conventionally used for vehicles such as automobiles and motorcycles is configured as follows. Engines are mounted in such vehicles and then a transmission device comprised of a group of gears links the engines to the drive wheels. The above described transmission devices change the engagement of the group of gears in order to change the gear ratio to obtain the desired speed. On the other hand, the above described engines are fitted with intake and exhaust valves that open and close the intake and exhaust openings of the intake and exhaust passages into the combustion chamber, and these valves are held in the normally closed position over the foregoing intake and exhaust valves by pneumatic springs. There are also intake and exhaust camshafts which are linked to the crankshaft of the foregoing engines which provide the cam system for the foregoing intake and exhaust valves. Then, when the engine is running, the foregoing intake and exhaust camshafts that are linked to the crankshaft overcome the force of the foregoing pneumatic springs by means of their cam system to appropriately open these valves. Through the repeated operation and use of these pneumatic springs, the air stored in their air chambers can gradually leak out, and conventionally a compressed-air cylinder is installed to replenish the compressed air in the foregoing air chambers. However, the above described conventional structure incurs the following problems. First, when the gear sets in the transmission device are tightly engaged, a considerable amount of effort is required to change the engagement of the gears in the transmission, and a stress on the operator of the vehicle ensues. Second, the problem with the requirement to install a compressed-air cylinder to replenish the compressed air in the air chambers of the pneumatic springs is that the compressed-air cylinder must be checked periodically for remaining air. When little air remains in the cylinder, it must be replaced with a new one, and such procedures complicate the maintenance and inspection of the foregoing pneumatic springs. From prior art document US-A 4,499,793 an automatic gear shifting device for operating a gear shift type transmission of a vehicle is known. Said vehicle comprises at least one camshaft for operating at least one intake valve and at least one exhaust valve. An air compressor driven by said engine is provided for supplying compressed air to an actuator of the gear shifting device. Said actuator is capable of delivering an operational force based on the supply of compressed air to assist the shifting operation of the transmission device. From prior art document FR-A 2 627 131 a pressure generator driven by an engine is known. Said pressure generator is connected with a motor shaft of said engine by a gearing means. Within said gearing means a camshaft driving gear is provided for driving a camshaft of said engine. It is an objective of the present invention to provide a compressed-air supply system for a vehicle as indicated above which is simple in construction and small in size. According to the present invention, said objective is solved by a compressed-air supply system as mentioned above, wherein said compressor comprises a piston rod which is coupled directly and eccentrically with an exhaust camshaft of the engine for driving the compressor. Accordingly, it is an advantage of the present invention to provided an improved compressed-air supply system for vehicles which is capable of lightening the operational load on an operator changing the engagement of the gears in the transmission. According to a preferred embodiment at least one air intake valve and said at least one exhaust valve are provided with pneumatic springs to hold said valves in a normally closed position and that a first regulator is provided communication with said pipe for regulating the air pressure in air chambers of said respective pneumatic springs. Further advantageous embodiments are laid down in the further dependent claims. The operation of one preferred embodiment is as follows. An air compressor is driven by the engine and supplies compressed air and that compressed air is fed to the actuators , which are capable of delivering an operational force based on that supply of compressed air Also, because the compressed air from the air compressor that is driven by the engine is also supplied to the pneumatic springs which exert a force on the intake and exhaust valves , there is no need to mount a compressed-air cylinder to supply the compressed air to the pneumatic springs , as it was in the prior art, thereby eliminating the need for inspection of the compressed-air cylinder for remaining compressed air, and for its replacement when empty. 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: Figure 1 is a sectional top view along line 1-1 of Figure 2. Figure 2 is a sectional side view of the engine. Figure 3 is a sectional view along line 3-3 of Figure 2. In the Figures, 1 represents a four-cycle, in-line, four cylinder internal combustion engine mounted in a vehicle such as an automobile. To facilitate the description, the arrow labeled "Fr" in the figures points toward the front, and references to "left" or "right" shall be based upon facing forward in the foregoing direction. Four cylinders 2, left and right, project upward from the crankcase of the foregoing engine 1. Each of these cylinders 2 is formed vertically into the cylinder block 4 and its axis 3 is parallel to the others. The cylinder bores 5 are formed into said cylinder block 4 along the above cylinder axes 3, a cylinder head 6 is mounted to the upward projecting end of the foregoing cylinder block 4, and a head cover 7 covers the top surface of this cylinder head 6. A number of fasteners removably hold the foregoing cylinder head 6 to the cylinder block 4. Pistons 10 have been inserted into the foregoing cylinder bores 5 and are free to slide up and down along the above mentioned cylindrical axes 3. The foregoing pistons 10 are linked to the crankshaft which is supported in the above mentioned crankcase by connecting rods 11. The spaces bounded by the foregoing cylinder block 4, cylinder head 6 and pistons 10 on the cylinder head 6 side comprise the combustion chambers 12. An air intake passage 14 extends from the back of the foregoing cylinder head 6 toward the front. On the upstream side of this air intake passage 14 are a throttle valve, mounted inside the air intake pipe 15 comprising the air intake pipe 14, a carburettor, and an air cleaner. On the downstream end of the foregoing air intake passage 14 are a plurality of double branches of which the ends, when viewed from the direction along the axes 3 of the cylinders 2 (a top view), open into the rear of the foregoing combustion chambers 12, wherein these various openings comprise the air intake openings 16. Air intake valves 18 open and close the foregoing air intake openings 16. These air intake valves 18 are equipped with valve stems 19 which are supported on the foregoing cylinder head 6 in a manner allowing them to freely slide up and down, and, integral valve bodies 20 are present at. the lower end of the valve stems 19. Pneumatic springs 21 mounted on these valve bodies 20 exert a force to maintain the foregoing air intake valves 18 normally closed over the air intake openings 16 on the combustion chamber 21 side. The foregoing pneumatic springs 21 are equipped with a bowl-shaped lower member 21a which is attached to the foregoing cylinder head 6 and which opens upward, and a bowl-shaped upper member 21b that is linked to the foregoing valve stem 19 and which opens downward. Both the lower member 21a and upper member 21b are mounted with the valve stem 19 as their axial center, and they are fitted to be freely slidable in the axial direction. Tightly sealed air chambers 21c are formed in the space surrounded by the foregoing lower member 21a and upper member 21b, and compressed air 22 is supplied to the inside of these air chambers 21c. The expansion of the foregoing air chambers 21c caused by this compressed air 22 causes the foregoing upper member 21b to rise, and the valve stem 20 of the air intake valve 18 causes the air intake valve opening 16 to close as described above. In addition, a dynamic valve mechanism 23 is located in the space encompassed by the foregoing cylinder head 6 and the cylinder head cover 7. This dynamic valve system is equipped with an air intake camshaft 24 with an axis that extends left and right. This air intake camshaft 24 is supported by bearings 26 on the foregoing cylinder head 6 that allow it to rotate around its axis. These bearings 26 consist of bearing areas 26a which support the foregoing air intake camshaft 24 on the bottom, and of covers 26b which cover the top half from above of the same air intake camshaft 24. These covers 26b are fastened by fasteners 26c to the foregoing bearing areas 26a. The foregoing air intake camshaft 24 is linked to the aforementioned crankshaft causing it to rotate around its axis. The rotation of the foregoing air intake camshaft 24 around its axis causes the lifters 25 on the upper-ends of the valve stems 19 to be engaged by the cams on the shaft, which, together with the force generated by the foregoing pneumatic springs 21, cause the foregoing air intake valves 18 to appropriately open and close the foregoing air intake valve openings 16. An exhaust passage 29 is present in the front of the foregoing cylinder head 6. The upstream end of this exhaust passage 29, when viewed along the axes 3 of the foregoing cylinders 2 (top view), comprises a plurality of double branches, and these branches open into the front side of the foregoing combustion chambers12, wherein these various openings comprise the exhaust openings 30. The downstream end of the foregoing air intake passage 29 connects to the exhaust pipe 31. Exhaust valves 32 are set in the foregoing exhaust openings 30 which open and close them. The valve stems 33 of these exhaust valves 32 are supported on the foregoing cylinder head 6 to be freely slidable up and down. Valve bodies 34 are integral with the lower end of these valve stems 33. Pneumatic springs 35 exert a force on the foregoing exhaust valves 32 to normally close the valve bodies 34 over the foregoing exhaust openings 30 on the combustion chamber side 12. These pneumatic springs 35 evince the same structure as the foregoing pneumatic springs 21, and their air chambers 35c between the lower members 35a and upper members 35b cause them to function in the same way. The above mentioned dynamic valve mechanism 23 is further equipped with an exhaust camshaft 37 of which the axis extends left and right. Bearings 26 on the foregoing cylinder head 6 allow this exhaust camshaft 37 to rotate around its axis and are of the same structure as the bearings 26 described above. The foregoing exhaust camshaft 37 is linked to the above mentioned crankshaft, which-causes it to rotate around its axis. The rotation around its axis by the foregoing exhaust camshaft 37 cause the lifters 38 on the tops of the foregoing valve stems 33 to be engaged by the cam system, which, along with the force generated by the foregoing pneumatic springs 35, cause the foregoing exhaust valves 32 to appropriately open and close the foregoing exhaust openings 30. In this configuration, the left end of the air intake camshaft 24 is linked to the foregoing crankshaft by means of a timing belt mechanism. In addition, a variable valve timing device 40 is attached to the other end of the foregoing air intake camshaft 24. This variable valve timing device 40 and the right end of the foregoing exhaust camshaft 37 are linked by a chain mechanism 41. This chain mechanism 41 is composed of a drive sprocket 41a attached to the foregoing variable valve timing device 40, of a follower sprocket 41b that is attached to the right end of the foregoing exhaust camshaft 37, and of a chain 41c spanning the drive sprocket 41a and the follower sprocket 41b. When the engine 1 is started, the air intake camshaft 24 linked to the crankshaft as described above will rotate. In addition, the exhaust camshaft 37 is rotated by the foregoing variable valve timing device 40 on the air intake camshaft 24 and the chain mechanism 41. In other words, the exhaust camshaft 37 is indirectly driven by the foregoing crankshaft. The operation of the foregoing variable valve timing device 40 enables the rotational timing of the exhaust camshaft 37 to be varied with respect to the foregoing air intake camshaft 24. In other words, it makes it possible to vary the timing (crank angle) of the opening and closing operation of the exhaust valves 32 with respect to the opening and closing operation of the air intake valves 18. Spark plugs 43 are affixed in the foregoing cylinder head 6, and the discharge area of each spark plugs 43 is situated at the edge of each of the foregoing combustion chambers 12. An electronic control device 44 controls the foregoing engine 1, and this control device 44 is electrically connected with the foregoing spark plugs 43. When the foregoing engine 1 is started, and a piston 10 descends from its upper dead point to its lower dead point in the air intake stroke, the air intake valves 18 are opened to open the air intake openings 16. At this time, the negative pressure created in the cylinder bore 5, the air intake passage 14 and the air intake pipe 15 causes outside air to be drawn in through the air cleaner toward the carburetor, where fuel is mixed with the air to create an air/fuel mixture 45. The air fuel mixture 45 passes through the foregoing air intake pipe 15 and the air intake passage 14 and through the gap between the inside circumferential surface of the foregoing air intake openings 16 and the valve body 20 of the air intake valve 18 to enter the foregoing combustion chamber 12. When the foregoing piston 10 reaches its lower dead point and begins its ascent for the compression stroke, and when the foregoing piston 10 reaches the vicinity of its upper dead point, the foregoing air/fuel mixture 45 in the combustion chamber 12 becomes adequately compressed. At this time, the control device 44 causes the spark plug 43 to emit an electrical discharge that ignites the foregoing air/fuel mixture 45 and burns it during the power stroke, causing the foregoing piston 10 to descend and to convert the heat of combustion into motive force. Continuing, this same piston 10 then begins ascending in the exhaust stroke, whereupon the gas generated by the foregoing combustion passes through the exhaust opening 30 which was opened by the operation of the exhaust valve 32, and then the gases are expelled from the cylinder 2 as exhaust through the exhaust passage 29, the exhaust pipe 31 and the muffler. Thereafter, the above described strokes are repeated, and the engine 1 delivers motive force. The foregoing engine 1 is linked by a transmission device 48 composed of gear sets to the drive wheels. When the speed is changed for the foregoing transmission levice 48, an actuator 49 consisting of an air cylinder assists in the shifting operation. In addition, the total length of the air intake passage of the foregoing air intake passage 14 and air intake pipe 15 can be varied. Specifically, the foregoing air intake pipe 15 consists of a sliding double-wall pipe, and an actuator 50 in the form of an air cylinder is used to change the length of this air intake pipe 15. Compressed air 22 is delivered from a reciprocating type of air compressor 52 that is driven by the foregoing engine 1. This air compressor 52 is removably attached to the top of the cylinder head cover 7 by bolts 53. A disc shaped support plate 55 is attached by a bolt 54 to the right end of the foregoing exhaust camshaft 34, and the end of a piston rod 56 of the foregoing air compressor 52 is axially supported by a shaft 57 on the foregoing support plate 55, wherein said shaft 57 is mounted to be eccentric with respect to the axis 58 of the exhaust camshaft 37. Then, when the engine 1 is started, the exhaust camshaft 37, which is driven by links to the crankshaft, causes the foregoing piston rod 56 to move reciprocally, which drives the air compressor 52 to output compressed air 22 from the compressor 52. The outlet of the foregoing air compressor 52 is connected to the foregoing actuator 49 through a regulator 61 and a valve 62, and an actuator 63 such as a magnetic valve, opens and closes the foregoing valve 62 and is electrically connected to the foregoing control device 44. In addition, the outlet of the foregoing air compressor 52 is connected to the foregoing actuator 50 through the foregoing air pipe 60, an accumulator 65, regulator 66 and valve 67. An actuator 68, such as a magnetic valve, opens and closes the foregoing valve 67, and is electrically connected to the foregoing control device 44. Also, a gear position sensor 70 is mounted on the foregoing transmission device 48 and detects whether or not the gear arrays are engaged (the gear position). This gear position sensor 70 is also electrically connected with the foregoing control device 44. Then, when changing the foregoing transmission device 48 to the desired gear ratio, the gear position sensor 70 detects the shifting operation, and that detection signal is fed into the foregoing control device 44. Thereupon, the control device 44 causes the actuator 63 to operate, whereby the valve 62 is opened and compressed air 22 is fed to the foregoing actuator 49. Next this compressed air 22 causes the foregoing actuator 49 to deliver an operational force to assist in the shifting of the foregoing transmission device 48. An operating-condition sensor 71 detects the operating condition of the engine 1 by detecting the RPM, etc, and this operating-condition sensor 71 is also electrically connected to the foregoing control device 44. When the control device 44 has received the detection signal from the foregoing operating condition detection sensor 71, it will drive the actuator 68 to appropriately adjust the valve 67 so that compressed air 22 is fed to the foregoing actuator 50. This compressed air 22 causes the foregoing actuator 50 to deliver an operational force, which adjusts the length of the foregoing air intake pipe 15. In other words, it is possible to adjust the length of the air intake pipe 15 without any operational force being supplied by the vehicle operator, and this action generates an air intake pulse that is beneficial in improving engine performance. The outlet of the foregoing air compressor 52 is also connected to each of the air chambers 21c, 35c of each above described pneumatic spring 21, 25 through the regulator 73, valve 74 and an air passage 75 in the cylinder head 6 to supply said chambers 21c, 35c with compressed air 22. Thus, should some compressed air 22 leak out of the foregoing pneumatic springs 21, 35, the continuous supply of compressed air 22 maintains these pneumatic springs at their normal pressure, thereby assuring that they generate the required force. In the embodiment shown in the figures, the air compressor 52 may equally well be driven by the air intake camshaft 24, or directly by the crankshaft. The present invention links an air compressor to the engine in order to deliver compressed air, and provides actuators generating operational forces based upon the supply of the foregoing compressed air. The operational force delivered by the foregoing actuators can be used to replace the operational force delivered by the vehicle operator or to lighten the force required of the operator thereby diminishing the operational stress on the operator of an operating vehicle. In addition, the compressor driven by the foregoing engine can also be used to provide compressed air to pneumatic springs exerting a force on the intake and exhaust valves, thereby eliminating the need to use a compressed-air cylinder as in the prior art to supply the pneumatic springs with compressed air, thereby eliminating the need to check such air cylinders for remaining air or to replace them when empty. This simplifies the inspection and maintenance of the pneumatic springs. Also, by providing this compressed air to the foregoing pneumatic springs, any leakage from them is replenished, while only requiring a very small amount of air. Accordingly, by additionally supplying compressed air to the springs as well as to the foregoing actuators, the foregoing actuators are able to deliver the desired operational force. To wit, not only is the load on the vehicle operator lightened by using the foregoing actuators, but the maintenance and inspection of the pneumatic springs are also simplified.

Claims: A compressed-air supply system for vehicles, comprising: at least one camshaft (24, 37) of an engine for operating at least one intake valve (18) and at least one exhaust valve (32) of said engine, and an air compressor (52) driven by said engine for supplying compressed air to a first actuator (49) via an air pipe (60), said first actuator (49) being capable of delivering an operational force based on the supply of compressed air to assist the shifting operation of a transmission device (48), characterized in that said compressor (52) comprises a piston rod (56) which is coupled directly and eccentrically with an exhaust camshaft (37) of the engine for driving the compressor (52). A compressed-air supply system according to claim 1, characterized in that said at least one air intake valve (18) and said at least one exhaust valve (32) are provided with pneumatic springs (21, 35) to hold said valves (18, 32) in a normal closed position, wherein a first regulator (73) is provided communicating with said pipe (60) for regulating an air pressure in air chambers (21c, 35c) of said respective pneumatic springs (21, 35). A compressed-air supply system according to claim 2, characterized in that a valve (74) is arranged between said first regulator (73) and said pneumatic springs (21, 35) which are operable by said first regulator (73). A compressed-air supply system according to at least one of the preceding claims 1 to 3, characterized in that a second actuator (50) is provided communicating with said pipe (60) being capable of generating an operational force based upon the compressed air to control a length of an air intake passage (14, 15). A compressed-air supply system according to claim 4, characterized in that a third regulator (66) is arranged between said air compressor (52) and said second actuator (50). A compressed-air supply system according to at least one of the preceding claims 1 to 5, characterized in that a second regulator (61) is provided between said air-compressor (52) and said first actuator (49). A compressed-air supply system according to at least one of the preceding claims 1 to 6, characterized in that said engine (1) comprises an air intake camshaft (24) for operating said at least one air intake valve (18) and said exhaust camshaft (37) for operating said at least one exhaust valve (32). A compressed-air supply system according to claim 7, characterized in that one end of the air intake camshaft (24) is linked to a crankshaft of said engine through a timing belt mechanism and another end of said air intake camshaft (24) is provided with a variable valve timing device (40). A compressed-air supply system for vehicles according to at least one of the preceding claims 1 to 8, characterized in that said compressor (52) is removably attached to a top of a cylinder head cover (7) of said engine.

Inventors: KIMURA TAKAAKI, KIMURA, TAKAAKI
Applicants: YAMAHA MOTOR CO LTD, YAMAHA HATSUDOKI KABUSHIKI KAISHA
Application year: 1995
Main classification: F02B67
IPC codes: F02B67, F01L3, F01L1, F02F7, F02B63