JP2006052708A - Fuel direct injection type internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel direct injection type internal combustion engine of a construction allowing a low cost and easy of maintenance. <P>SOLUTION: The engine 50 has the construction that high pressure air generated by an air pump 80 is mixed with fuel to provide a mixture and the mixture is directly injected into a combustion chamber 62 of a cylinder 56 though an injector 75 mounted to a cylinder head 52. The cylinder head 52 is provided with a cam shaft 60 driving an intake valve 71 and an exhaust valve 72 for causing intake and exhaust of the combustion chamber 62. The air pump 80 has a pump case 65 formed in the cylinder head 52 and a pump piston 81 reciprocating in the pump case 65. The pump piston 81 is driven by the cam shaft 60. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a direct fuel injection type internal combustion engine in which an air-fuel mixture obtained by mixing fuel with high pressure air is directly injected into a combustion chamber of the internal combustion engine by an injector, and more specifically, an air pump for supplying high pressure air to the injector. Concerning the arrangement configuration.

  A fuel direct injection internal combustion engine configured to inject a high-pressure air-fuel mixture directly into a combustion chamber by an injector is known, and as such an injector, a type in which fuel pressurized by a high-pressure pump is injected into a combustion chamber, or a high-pressure A configuration in which an air-fuel mixture obtained by injecting fuel into air is injected into a combustion chamber is known.

The latter so-called air assist type injector requires an air pump for generating high-pressure air, and is generally provided on the side of the crankcase or cylinder (that is, in the cylinder block). A piston type is often used for this air pump, and its driving force is obtained by converting the rotational motion of a shaft member that rotates in synchronization with the crankshaft into linear motion (for example, see Patent Document 1 below). The generated high-pressure air is supplied to an injector provided in the cylinder head through an internal pipe provided in the cylinder block and in the cylinder head, in addition to an external pipe such as a hose.
Japanese Patent Laid-Open No. 2004-60609 JP 2003-184688 A

  However, the above-described conventional configuration has a problem that the pipe for supplying the high-pressure air generated by the air pump to the injector in the cylinder head becomes long, the structure is complicated, and maintenance is difficult. Further, since the air pump has a configuration in which the rotational power of the camshaft is driven through a chain or the like and a shaft member, there is a problem that the number of parts increases, and in addition to manufacturing costs, maintenance costs are also required.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a fuel direct injection internal combustion engine having a structure that can be made inexpensive and easy to maintain.

  A fuel direct injection internal combustion engine according to the present invention is a direct fuel injection system in which an air-fuel mixture obtained by mixing fuel with high-pressure air generated by an air pump is directly injected into a combustion chamber of a cylinder by an injector attached to the cylinder head. In an injection internal combustion engine, a cylinder head has an intake valve for intake / exhaust of a combustion chamber and a camshaft for driving the exhaust valve, and an air pump reciprocates within the pump case and the pump case formed in the cylinder head. The pump piston is driven by a camshaft.

  In the fuel direct injection internal combustion engine, the axis of the pump case is preferably parallel to the axis of the cylinder. In the direct fuel injection internal combustion engine, it is preferable that the injector extends so as to be substantially along the axis of the cylinder, and the camshaft is positioned on the side of the injector.

  In the direct fuel injection internal combustion engine according to the present invention, an air pump that generates high-pressure air mixed with fuel is provided in the cylinder head, and this air pump is also driven by a camshaft provided in the cylinder head. Therefore, the pipe line for guiding the high-pressure air generated by the air pump to the injector can be shortened compared to the conventional case, and the maintenance becomes very easy. Further, since the air pump is directly driven by the camshaft, the number of parts is reduced as compared with the conventional one, and the cost for manufacturing and maintenance can be reduced. Further, since the pump case and the pump piston constituting the air pump are arranged in the cylinder head, the lubricating oil for camshaft lubrication can be used as it is for lubricating the sliding portion between the pump piston and the pump case. As a result, the lubricating oil supply structure can be simplified (shared).

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a scooter type motor-equipped bicycle (hereinafter referred to as a scooter) 1 including a direct fuel injection internal combustion engine according to a first embodiment of the present invention. The scooter 1 includes a vehicle body portion B and a power portion D, and the vehicle body portion B includes a frame 10 and a body cover 20. The frame 10 includes left and right main tubes 11, a head pipe 12 that is attached to the front end portions of the left and right main tubes 11 so as to extend obliquely in the vertical direction. Left and right down tubes 13 coupled to the rear end, left and right seat rails 14 extending rearward and upward from an intermediate portion of the left and right main tubes 11, a connecting tube 15 connecting the intermediate portion of the seat rail 14 and the main tube 11, a main A floor frame 16 provided outside the tube 11 and the down tube 13, a swing arm 17 whose front end is pivotally connected to a pivot 15 a formed in the connecting tube 15, and the like are configured.

  A steering shaft 18 is inserted through the head pipe 12, and a bar handle 30 is attached to the upper end portion of the steering shaft 18. Left and right front forks 19 with front suspensions extend downward from the lower end of the steering shaft 18, and a front wheel 41 is rotatably supported on the lower ends of the left and right front forks 19.

  The body cover 20 is provided so as to cover the entire vehicle body part B. The body cover 20 includes a front cover 21 that covers the front of the head pipe 12, left and right front side covers 22 that cover the sides of the head pipe 12, the front of the main tube 11 and the down tube 13, a rear portion of the main tube 11, and a seat. A floor center cover 23 covering the front part of the rail 14, left and right floor side covers 24 covering the rear part of the down tube 13, the rear part of the main tube 11 and the upper part of the floor frame 16, and left and right bodies covering the rear part of the seat rail 14. The side cover 25 includes left and right rear center covers 26 and a rear lower cover 27 that cover the rear of the seat rail 14.

  A windshield 31 and a meter visor 32 are attached to the upper portion of the front cover 21, and a rider seat 33 and a passenger seat 34 are provided above the seat rail 14. A front fender 35 is attached to the lower part of the left and right front side covers 22, and a rear fender 36 is attached to the lower part of the rear lower cover 27. A tail lamp unit 37 is provided at the lower part of the rear center cover 26. The upper surfaces of the left and right floor side covers 24 are formed flat to serve as a footrest for a person (driver) sitting on the rider seat 33, and in the middle of the connecting tube 15, the legs of the person sitting on the passenger seat 34. A tandem step 38 used as a stand is attached. A main stand 43 is swingably attached to a rear end portion of the main tube 11, and a side stand 44 is swingably attached to an intermediate portion of the left down tube 13.

  A rear wheel 42 is rotatably supported at the rear portion of the swing arm 17. A lower end of a rear suspension 39 having an upper end attached to the rear end portion of the seat rail 14 is attached to the rear end portion of the swing arm 17, and an impact received by the rear wheel 42 is applied to the rear suspension via the swing arm 17. 39 is absorbed. In addition, a power unit D is mounted on the swing arm 17. The power unit D includes an engine 50, a transmission 90, and the like. The engine 50 is a direct fuel injection type internal combustion engine according to the first embodiment of the present invention, and the transmission 90 is a continuously variable drive comprising a drive pulley 91, a driven pulley 92, and a drive belt 93 spanned between these pulleys 91, 92. Consists of anomalous mechanism.

  The engine 50 is a single-cylinder, two-valve, four-stroke, crank-type engine. As shown in FIGS. 2 and 3, the cylinder block 51, the cylinder head 52 and the crankcase 53, the crankshaft 55, the cylinder 56, and the piston 57 are used. , A connecting rod 58, a camshaft 60, an intake valve 71 and an exhaust valve 72, an air pump 80, a fuel injection valve 69, an injector 75, a spark plug 76, and the like.

  The crankcase 53 is joined to the lower part of the cylinder block 51, and the cylinder head 52 is joined to the upper part of the cylinder block 51. The cylinder head 52 includes a cylinder head main body 52a joined to the cylinder block 51 and a cylinder head cover 52b joined to the upper portion of the cylinder head main body 52a. The crankshaft 55 is rotatably supported in the crankcase 53, and a drive pulley 91 of the transmission 90 is connected to the left end side of FIG. 2 via a centrifugal clutch (not shown). The cylinder 56 is formed in the cylinder block 51, and the piston 57 is swingably attached to the end of a connecting rod 58 connected to the crankshaft 55 via a piston pin 59.

  The camshaft 60 is rotatably supported in the cylinder head 52 and is driven to rotate by a crankshaft 55 via a chain 61. The intake valve 71 is a valve for performing intake and intake between the combustion chamber 62 and the intake port 63 into the combustion chamber 62 formed by being surrounded by the cylinder 56, the piston 57, and the cylinder head 52, The combustion chamber 62 and the intake port 63 are always urged by the valve spring 71a in the closing direction, but the intake valve drive cam 60a formed on the camshaft 60 moves downward through the intake valve drive rocker arm 73. When the pressure is pressed, the combustion chamber 62 and the intake port 63 are communicated with each other. The exhaust valve 72 is a valve that performs exhaust from the combustion chamber 62, that is, a communication between the combustion chamber 62 and the exhaust port 64, and a direction in which the combustion chamber 62 and the exhaust port 64 are always closed by a valve spring 72a. However, when the exhaust valve driving cam 60b formed on the camshaft 60 is pressed downward via the exhaust valve driving rocker arm 74, the combustion chamber 62 and the exhaust port 64 are connected to each other. It comes to communicate. Here, the support shaft 73a for swingably supporting the intake valve drive rocker arm 73 and the support shaft 74a for swingably supporting the exhaust valve drive rocker arm 74 are parallel to each other as shown in FIG. They are arranged and supported by the cylinder head 52 respectively.

  The air pump 80 includes an inner cylindrical pump case 65 formed in the cylinder head 52 (cylinder head cover 52b), a pump piston 81 movable in the pump case 65, and a pump having one end formed on the camshaft 60. The pump rod 82 is connected to the drive cam 60c and has the pump piston 81 on the other end side. Here, the pump case 65 is provided such that its axis AX2 is parallel to the axis AX1 of the cylinder 56 (see FIGS. 2 and 3), and when the crankshaft 55 rotates, the rotational force causes the chain 61 to move. And the pump rod 82 moves in the same direction as the movement direction of the piston 57 (in the up and down direction in FIG. 2) via the pump drive cam 60c. For this reason, the pump piston 81 reciprocates in the pump case 65.

  In the suction process of the air pump 80 (the process of moving the pump piston 81 downward in FIG. 2), the air suction port 66 provided in the head cap 54 attached to the cylinder head 52 so as to close the end of the pump case 65. In the discharge process of the air pump 80 (the process of moving the pump piston 81 upward in the drawing in FIG. 2), high-pressure air is passed through the head cap 54 and the cylinder head 52 (see FIG. 3). 67a, 67b, 67c, 67d, 67e) and supplied to the injector 75. Note that an air regulator 68 is interposed in an intermediate portion of the air passage 67 (between the air passages 67c and 67d). When excess air is released here, air having an appropriate pressure is supplied to the injector 75. It has become so. On the other hand, the fuel (here, gasoline) is attached to the cylinder head 52 and is supplied into the injector 75 from a fuel injection valve 69 (see FIG. 3) connected to a fuel tank and a fuel pump (not shown).

  2 and 3, the injector 75 extends so as to be substantially along the axis AX1 of the cylinder 56, and projects the injection port 75a into the combustion chamber 62 (the camshaft 60 is shown in FIG. 2). And located on the side of the injector 75), as shown in FIG. The injector 75 mixes the high-pressure air generated and supplied by the air pump 80 and the fuel inside as described above, and directly injects and injects the resultant air-fuel mixture into the combustion chamber 62 in the compression process. When the air-fuel mixture is ignited by the spark plug 76 immediately after the injection of the air-fuel mixture, the air-fuel mixture explodes (combusts) and pushes down the piston 57, so that the crankshaft 55 rotates thereby, and the above-mentioned centrifugal type (not shown) The drive pulley 91 is rotationally driven via the clutch. The rotational force of the drive pulley 91 is transmitted to the driven pulley 92 via the drive belt 93, and further transmitted to a gear mechanism (not shown) to drive the rear wheel 42.

  As described above, in the engine 50 according to the first embodiment, the air pump 80 that generates high-pressure air to be mixed with fuel is provided in the cylinder head 52, and the camshaft 60 is also provided in the cylinder head 52. Therefore, the conduit (air passage 67) for guiding the high-pressure air generated by the air pump 80 to the injector 75 can be shortened compared to the conventional case, and the maintenance becomes very easy. Further, since the air pump 80 is directly driven by the camshaft 60, the number of parts is reduced as compared with the conventional case, and the cost for manufacturing and maintenance can be reduced. Further, since the pump case 65 and the pump piston 81 constituting the air pump 80 are arranged in the cylinder head 52, the lubricating oil for lubricating the camshaft 60 is directly slid between the pump piston 81 and the pump case 65. It becomes possible to divert the lubrication of the moving part, and the lubrication oil supply structure can be simplified (shared).

  Further, in the engine 50 according to this embodiment, as described above, since the axis AX2 of the pump case 65 is parallel to the axis AX1 of the cylinder 56, the lateral direction of the cylinder 56 (of the cylinder 56) There is little overhang in the off-axis direction). For this reason, it is possible to widen the footrest space even when the engine 50 is mounted on the scooter 1 in a crank lateral state as in the above embodiment.

  In the engine 50 according to the present embodiment, the injector 75 extends so as to be substantially along the axis AX <b> 1 of the cylinder 56, and the camshaft 60 is arranged to be shifted to the side of the injector 75. For this reason, the injector 75 can be installed in the center part of the combustion chamber 62, the adhesion of fuel to the inner wall surface of the cylinder 56 can be reduced, and the combustion efficiency can be improved.

  Next, a direct fuel injection internal combustion engine according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 6 shows a motorcycle 101 including an engine 150 according to the second embodiment of the present invention. The motorcycle 101 includes a left and right main tube 111, a head pipe 112 attached to the front end portions of the left and right main tubes 111 in an obliquely extending direction, a front end portion coupled to the head pipe 112, and a rear end portion. Are formed in a substantially U-shaped left and right down tube 113 coupled to the rear end of the main tube 111, left and right seat rails 114 extending rearward and upward from the rear end of the left and right main tube 111, and the left and right main tubes 113. A swing arm 117 having a front end portion pivoted on the pivot 113a is provided.

  A steering shaft 118 is inserted through the head pipe 112, and a handle 130 is attached to the upper end portion of the steering shaft 118. Left and right front forks 119 with a front suspension extend downward from a lower end portion of the steering shaft 118, and a front wheel 141 is rotatably supported on the lower end portions of the left and right front forks 119.

  A rider seat 133 and a passenger seat 134 are provided above the seat rail 114. A front fender 135 is attached to the front fork 119, and a rear fender 136 is attached to the lower portion of the seat rail 114. In addition, a tail lamp unit 137 is provided at the rear part of the rear fender 136, and a step 138 is provided in the middle part of the left and right down tubes 113 as a footrest for a person (driver) sitting on the rider seat 133. Yes. A main stand 143 is swingably attached to an intermediate portion of the down tube 113.

  A rear wheel 142 is rotatably supported at the rear portion of the swing arm 117. At the rear of the swing arm 117, a lower end of a rear suspension 139 having an upper end attached to the seat rail 114 is attached, and the impact of the rear wheel 142 is absorbed by the rear suspension 139 via the swing arm 117. ing. An engine 150 and a transmission 190 connected to the engine 150 are accommodated in a space between the main tube 111 and the down tube 113, and the power of the engine 150 transmitted to the transmission 190 is transmitted to the rear of the swing arm 117. A power transmission device 195 such as a propeller shaft for transmitting to the wheel 142 is provided.

  The engine 150 is a V-type 2-cylinder 3-valve 4-stroke type crank horizontal installation engine. As shown in FIGS. 7 and 8, one cylinder includes a cylinder block 151, a cylinder head 152 and a crankcase 153, a crankshaft 155, a cylinder 156, a piston 157, a connecting rod 158, a camshaft 160, intake valves 171 and 171. ', An exhaust valve 172, an air pump 180, a fuel injection valve (not shown), an injector 175, a spark plug (not shown), and the like.

  The crankcase 153 is joined to the lower part of the cylinder block 151, and the cylinder head 152 is joined to the upper part of the cylinder block 151. The cylinder head 152 includes a cylinder head main body 152a connected to the cylinder block 151, and a cylinder head cover 152b joined to the upper portion of the cylinder head main body 152a. The crankshaft 155 is rotatably supported in the crankcase 153, and a drive gear (not shown) for driving an input shaft (not shown) of the transmission 190 is provided at an end of the crankshaft 155. The cylinder 156 is formed in the cylinder block 151, and the piston 157 is attached to the end of a connecting rod 158 connected to the crankshaft 155 via a piston pin 159.

  The camshaft 160 is rotatably supported in the cylinder head 152 and is rotationally driven by a crankshaft 155 via a chain (not shown). The two intake valves 171 and 171 ′ are valves that perform intake into the combustion chamber 162 formed by being surrounded by the cylinder 156, the piston 157, and the cylinder head 152, and are always burned by the valve springs 171a and 171′a, respectively. The chamber 162 and the intake port 163 are urged in the closing direction, but are pressed downward by the intake valve drive cam 160a formed on the camshaft 160 via the intake valve drive rocker arm 173. The combustion chamber 162 and the intake port 163 communicate with each other. Further, the exhaust valve 172 is a valve for exhausting from the combustion chamber 162 and is always urged in a direction to close the combustion chamber 162 and the exhaust port 164 by a valve spring 172a, but is also formed on the camshaft 160. When the exhaust valve driving cam 160b is pressed downward via the exhaust valve driving rocker arm 174, the combustion chamber 162 and the exhaust port 164 are communicated with each other. Here, the support shaft 173a for swingably supporting the intake valve drive rocker arm 173 and the support shaft 174a for swingably supporting the exhaust valve drive rocker arm 174 are shown in FIGS. Are parallel to each other and supported by a cylinder head 152.

  As shown in FIG. 8, the air pump 180 includes an inner cylindrical pump case 165 formed in the cylinder head 152, a pump piston 181 movable within the pump case 165, and one end side formed on the camshaft 160. And a pump rod 182 having the pump piston 181 on the other end side. Here, the pump case 165 is provided so that its axis AX12 extends in a direction inclined with respect to the axis AX11 of the cylinder 156 (here, a direction substantially orthogonal to the plane of FIG. 7). When the shaft 155 rotates, the rotational force is transmitted to the camshaft 160 via the above-described chain (not shown), and the pump rod 182 is tilted with respect to the moving direction of the piston 157 via the pump drive cam 160c (see FIG. 7 in the horizontal direction of the drawing). For this reason, the pump piston 181 reciprocates in the pump case 165. In this embodiment, the fact that the axis AX12 of the pump case 165 is inclined (not parallel) to the axis AX11 of the cylinder 156 is narrow in the space above the engine 150, as can be seen from FIG. This is because it is difficult to project the air pump 180 upward as described above.

  In the suction process of the air pump 180 (the process of moving the pump piston 181 leftward in FIG. 7), the air suction port provided in the head cap 154 attached to the cylinder head 152 so as to close the end of the pump case 165 166 (see FIG. 7), outside air is sucked in, and in the discharge step of the air pump 180 (the step of moving the pump piston 181 rightward in FIG. 7), the high-pressure air is supplied to the air passage 167 (the air passage 167a in the head cap 154, The air is supplied to the injector 175 through an air passage 167b formed of a hose provided between the head cap 154 and the cylinder head 152, and air passages 167c and 167d provided in the cylinder head 152. In addition, an air regulator 168 is interposed in an intermediate portion of the air passage 167 (between the air passages 167c and 167d), and air with an appropriate pressure is supplied to the injector 175 when excess air is released here. The On the other hand, fuel (here, gasoline) is supplied into the injector 175 from a fuel injection valve (not shown) attached to the cylinder head 152.

  As shown in FIG. 7, the injector 175 extends so as to be substantially along the axis AX11 of the cylinder 156, and the injection port 175a protrudes into the combustion chamber 162 (the camshaft 160 is as shown in FIG. 8). In the side of the injector 175). The injector 175 mixes the high-pressure air generated and supplied by the air pump 180 and the fuel inside as described above, and directly injects and injects the resulting air-fuel mixture into the combustion chamber 162 in the compression process. Immediately after the injection of the air-fuel mixture, if the air-fuel mixture is ignited by the ignition plug (not shown), the air-fuel mixture explodes (combusts) and pushes down the piston 157, so that the crankshaft 155 rotates and the power is This is transmitted to the power transmission device 195 via the transmission 190. The power of the engine 150 transmitted to the power transmission device 195 is further transmitted to a gear mechanism (not shown), and the rear wheel 142 is finally driven.

  As described above, also in the engine 150 according to the second embodiment, the air pump 180 that generates high-pressure air mixed with the fuel is provided in the cylinder head 152, and the camshaft in which the air pump 180 is also provided in the cylinder head 152. 160, the pipe (air passage 167) for guiding the high-pressure air generated by the air pump 180 to the injector 175 can be shortened compared to the conventional case, and the maintenance becomes very easy. . Further, since the air pump 180 is directly driven by the camshaft 160, the number of parts is reduced as compared with the conventional one, and the cost for manufacturing and maintenance can be reduced. Similarly to the case of the first embodiment, the pump case 165 and the pump piston 181 constituting the air pump 180 are disposed in the cylinder head 152, so that the lubricating oil for lubricating the camshaft 160 is directly used as the pump piston 181. And the pump case 165 can be used for lubrication of the sliding portion, and the lubricating oil supply structure can be facilitated (shared).

  Also, in the engine 150 according to the second embodiment, the injector 175 extends so as to be substantially along the axis AX11 of the cylinder 156, and the camshaft 160 is arranged to be shifted to the side of the injector 175. The injector 175 can be installed at the center portion of the combustion chamber 162, so that fuel adhesion to the inner wall surface of the cylinder 156 can be reduced, and combustion efficiency can be improved.

  Although the preferred embodiments of the present invention have been described so far, the scope of the present invention is not limited to those shown in the above-described embodiments. For example, although the number of intake valves and exhaust valves is one or two in the above-described embodiment, these are examples, and the number of valves is not limited to the above-described embodiment. Further, in the above-described embodiment, the direct fuel injection type internal combustion engine according to the present invention is provided in a scooter type motorbike or motorcycle, but this is an example, and it is used as a power source for other power machines. Of course it is also possible.

1 is a side view of a scooter type motor-equipped bicycle equipped with an engine according to a first embodiment of the present invention. It is sectional drawing of the said engine seen from the arrow II-II in FIG. It is sectional drawing of the said engine seen from the arrow III-III in FIG. It is sectional drawing of the said engine seen from arrow IV-IV in FIG. FIG. 5 is a partial cross-sectional view seen from an arrow V in FIG. 4. It is a side view of the scooter type motor-equipped bicycle equipped with the engine according to the second embodiment of the present invention. FIG. 7 is an enlarged partial sectional view of the engine in FIG. 6. It is sectional drawing of the said engine seen from the arrow VIII-VIII in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bicycle with scooter type motor 50 Engine 51 Cylinder block 52 Cylinder head 53 Crankcase 55 Crankshaft 56 Cylinder 57 Piston 58 Connecting rod 60 Camshaft 60a Intake valve drive cam 60b Exhaust valve drive cam 60c Pump drive cam 62 Combustion chamber 65 Pump case 67 Air passage 71 Intake valve 72 Exhaust valve 75 Injector 75a Injection port 80 Air pump 81 Pump piston 82 Pump rod

Claims (3)

In a fuel direct injection internal combustion engine configured to directly inject a mixture obtained by mixing fuel with high-pressure air generated by an air pump into a combustion chamber of a cylinder by an injector attached to the cylinder head.
The cylinder head has an intake valve for intake and exhaust of the combustion chamber and a camshaft for driving the exhaust valve,
The air pump includes a pump case formed in the cylinder head and a pump piston that reciprocates in the pump case, and the pump piston is driven by the camshaft. Type internal combustion engine. 2. The direct fuel injection internal combustion engine according to claim 1, wherein an axis of the pump case is parallel to an axis of the cylinder. 3. The direct fuel injection type internal combustion engine according to claim 1, wherein the injector extends so as to be substantially along an axis of the cylinder, and the camshaft is positioned on a side of the injector. 4.

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