JP2005325814A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve thermal efficiency of an internal combustion engine provided with a fuel injection device for injecting and supplying fuel into a combustion chamber 4 directly. <P>SOLUTION: This engine E is provided with a cylinder block 1, a piston 3 fitting slidably into the cylinder block 1, a crankshaft 5 connected with the piston 3, and a connecting means 10 connecting the piston 3 with the crankshaft 5. The connecting means 10 has a link mechanism 19 reducing lowering speed of the piston 3 corresponding to rotation of the crankshaft 5 more than lifting speed of the piston 3, and this engine comprises the fuel injection device for injecting and supplying fuel into the combustion chamber 4 directly. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine in which a piston slidably fitted into a cylinder is connected to a crankshaft through connecting means.

  In the internal combustion engine as described above, for example, as disclosed in Japanese Patent Application Laid-Open No. 2000-55164 and Japanese Patent Application Laid-Open No. 7-11971, a connecting rod (connecting means) for connecting a piston and a crankshaft is provided. It is known that the first connecting rod on the piston side and the second connecting rod on the crankshaft side are divided into two parts and pivotally connected by an intermediate pin, and the intermediate pin and the fixed part are connected by a link arm.

By the way, in order to improve the thermal efficiency by increasing the equal volume at the time of combustion of the air-fuel mixture in the internal combustion engine, and to improve the intake efficiency and reduce the pumping loss, the piston is slowly moved from the top dead center in the expansion stroke. It is desirable to descend (at low speed). In view of this, for example, as disclosed in Japanese Patent Application Laid-Open No. 2003-83101, an internal combustion engine has been devised in which the change in the crank angle of the expansion stroke (and the intake stroke) is greater than 180 °. By doing so, the piston lowering speed near the top dead center becomes slower than the conventional one, so that the thermal efficiency can be improved by increasing the isovolume by completing the combustion in the meantime.
JP 2003-83101 A

  However, in the internal combustion engine as described above, there is a problem that the heat loss increases because the volume of the combustion chamber is small and the time during which the pressure is high becomes long. Further, in order to reduce such heat loss, it is known that even if the temperature of the cooling water is raised or the amount of cooling water is reduced, the exhaust loss increases and it is difficult to improve the thermal efficiency.

  The present invention has been made in view of such a problem, and an object thereof is to improve the thermal efficiency of an internal combustion engine.

  In order to achieve such an object, in the present invention, a cylinder (for example, the cylinder block 1 in the embodiment), a piston slidably fitted to the cylinder, a crankshaft connected to the piston, a piston and a crankshaft An internal combustion engine (for example, in the embodiment) configured to have a link mechanism that makes the lowering speed of the piston smaller than the rising speed of the piston according to the rotation of the crankshaft. The engine E) includes a fuel injection device (for example, the fuel-air mixture injector 100 in the embodiment) that directly injects fuel into the combustion chamber of the internal combustion engine.

  In the above-described invention, the link mechanism includes a first connecting rod having one end pivotally connected to the piston and the other end provided with an intermediate pin, and one end pivotally connected to the intermediate pin and the other end to the crankshaft. A second connecting rod that is pivotally connected, a fixed portion that is pivotally connected at one end to the intermediate pin and at the other end below the crankshaft, and a link arm that is pivotally connected, and the piston is located at top dead center The direction of the first connecting rod is substantially parallel to the central axis of the cylinder (for example, the axis L2 of the cylinder block 1 in the embodiment), and the direction of the second connecting rod is substantially perpendicular to the central axis of the cylinder. It is preferable that it is comprised so that it may become.

  Furthermore, in the second invention, a cylinder, a piston slidably fitted in the cylinder, a crankshaft connected to the piston, and a connecting means for connecting the piston and the crankshaft (for example, the connecting rod in the embodiment) 421) and a cylinder head that is provided at one end of the cylinder and forms a combustion chamber between the piston and the piston, and the cylinder head is disposed between the piston and the crankshaft ( For example, the engine E2) in the embodiment includes a fuel injection device that directly injects and supplies fuel into the combustion chamber.

  In each of the above-described inventions, the fuel injection device is configured to inject and supply an air-fuel mixture in which fuel and compressed air are mixed into the combustion chamber, and the piston is configured to supply the air-fuel mixture injected from the fuel injection device. It is preferable to be configured with a cavity that receives the majority.

  According to the present invention, heat loss is reduced by stratified combustion using a fuel injection device. Therefore, the effect of reducing the piston speed near top dead center leads to improvement in thermal efficiency, and the thermal efficiency of the internal combustion engine can be improved. .

  In the above invention, when the piston is located at the top dead center, the direction of the first connecting rod is substantially parallel to the central axis of the cylinder, and the direction of the second connecting rod is aligned with the central axis of the cylinder. By being configured to be substantially perpendicular to the cylinder, the size of the internal combustion engine in the direction of the central axis of the cylinder can be reduced.

  Further, according to the second invention, since the lowering speed and the rising speed of the piston according to the rotation of the crankshaft near the top dead center are smaller than those of the conventional one, similarly, the By reducing the heat loss, the effect of reducing the piston speed near the top dead center leads to the improvement of the thermal efficiency, and the thermal efficiency of the internal combustion engine can be improved. Furthermore, since the piston ascending speed can also be reduced, the fuel injection timing is advanced, fuel atomization is improved, and the thermal efficiency of the internal combustion engine can be further improved.

  Further, in each of the above-described inventions, since the piston is configured to include a cavity portion that receives most of the air-fuel mixture, the air-fuel mixture can be sufficiently secured in the cavity portion, so that more stable stratified combustion is achieved. It becomes possible.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 and FIG. 2 show an engine E which is an example of an internal combustion engine according to the present invention. The engine E is a single-cylinder engine mounted on a two-wheeled vehicle, and transmits (shifts) the rotational driving force of the crankshaft 5 by a transmission (not shown) to rotationally drive a rear wheel (not shown) of the two-wheeled vehicle. It is configured. In the present specification, the direction of the top dead center and the direction of the bottom dead center of the piston 3 configured in the engine E are defined as upward and downward, respectively.

  The engine E includes a cylinder block 1 having a cylindrical cylinder inner peripheral surface 1a, and a cylinder head 2 attached so as to cover the upper surface of the cylinder block 1. The piston 3 is fitted to the peripheral surface 1a) so as to be slidable in the axial direction. On the upper surface of the piston 3, there is a cavity portion (dish-shaped depression) 3b for receiving the air-fuel mixture injected from the air-fuel mixture injector 100, which will be described later, and making the air-fuel mixture easy to burn during the compression stroke. Is provided.

  As shown in FIG. 1, a spark plug 21 and an air-fuel mixture injector 100 are attached to the cylinder head 2, and in the combustion block 4 surrounded by the cylinder head 2 and the piston 3 in the cylinder block 1, A mixture of compressed air and fuel is injected from the mixture injector 100 and ignited and burned by the spark plug 21. As shown in FIG. 2, an intake valve 23 and an exhaust valve 24 are attached to the cylinder head 2 while being urged in the closing direction by valve springs 23 a and 24 a, and the intake valve 23 is formed in the cylinder head 2. The opened intake passage 2a is opened and closed, and the exhaust valve 24 opens and closes the exhaust passage 2b. An intake manifold 25 is connected to the intake passage 2a, and an exhaust manifold (not shown) is connected to the outlet end 2c of the exhaust passage 2b.

  In the housing HSG that supports the cylinder block 1, as shown in FIG. 2, a crank that extends at right angles to the axis L <b> 2 of the cylinder block 1 (the central axis of the space formed by being surrounded by the cylinder inner peripheral surface 1 a). The shaft 5 is rotatably attached. The crankshaft 5 is connected to the piston 3 by using connecting means 10 including first and second connecting rods 11, 12, and the axis L 1 (center axis) of the crankshaft 5 is relative to the axis L 2 of the cylinder block 1. So that they are biased to one side.

  The first connecting rod 11 is formed so as to extend in the vertical direction. One end of the first connecting rod 11 is pivotally connected to the piston 3 via a piston pin 3 a, and the other end of the second connecting rod 12 is connected via an intermediate pin 13. Pivot with one end. The second connecting rod 12 is formed so as to extend in the left-right direction. One end of the second connecting rod 12 is pivotally connected to the other end of the first connecting rod 11 via the intermediate pin 13, and the other end is connected via the crank pin 5a. It is pivotally connected to the crankshaft 5. One end of a link arm 14 is pivotally connected to the intermediate pin 13, and the other end is pivotally connected to a fixed portion 15 located below the crankshaft 5 via a fulcrum pin 16.

  When the piston 3 is at the top dead center, the axis L3 of the first connecting rod 11 (that is, the line connecting the axis L4 of the piston pin 3a and the axis L5 of the intermediate pin 13) is substantially equal to the axis L2 of the cylinder block 1. The axis L6 of the second connecting rod 12 (that is, the line connecting the axis L5 of the intermediate pin 13 and the axis L7 of the crank pin 5a) is substantially perpendicular to the axis L3 of the first connecting rod 11. ing. That is, when the piston 3 is located at the top dead center, the direction of the first connecting rod 11 is substantially parallel to the axis L2 of the cylinder block 1 (the central axis of the space formed by being surrounded by the cylinder inner peripheral surface 1a). In addition, the direction of the second connecting rod 12 is configured to be substantially perpendicular to the axis L2 of the cylinder block 1. At this time, the axis L8 of the link arm 14 (that is, the line connecting the axis L5 of the intermediate pin 13 and the axis L9 of the fulcrum pin 16) is lowered to the left in FIG. 2 with respect to the axis L3 of the first connecting rod 11. It is inclined to.

  In addition, the said 1st connecting rod 11, the 2nd connecting rod 12, and the link arm 14 comprise the link mechanism 19 in this invention.

  Further, the rotation direction of the crankshaft 5 is set to a direction in which the crankpin 5a is lowered and then lowered while the piston 3 is lowered from the top dead center to the bottom dead center.

  FIG. 3 shows a state when the piston 3 is at the bottom dead center. When the piston 3 moves from the top dead center to the bottom dead center, the axis L5 of the intermediate pin 13 located at the lower end of the first connecting rod 11 is constrained by the link arm 14 and centered on the axis L9 of the fulcrum pin 16 Move on arc R. In the meantime, the axis L5 of the intermediate pin 13 does not come out on the left side in the drawing with respect to the axis (center axis) L2 of the cylinder block 1.

  The crankshaft 5 rotates 216 ° while the piston 3 moves from the top dead center to the bottom dead center, and the crankshaft 5 rotates 144 ° while the piston 3 moves from the bottom dead center to the top dead center. That is, in the engine E of this embodiment, the link mechanism 19 causes the expansion stroke and the intake stroke period (crank angle) to be longer than the compression stroke and the exhaust stroke period (crank angle), and responds to the rotation of the crankshaft 5. The descending speed of the piston 3 is smaller than the ascending speed of the piston 3.

  FIG. 4 shows the relationship of the stroke of the piston with respect to the crank angle. The two-dot chain line is a conventional arrangement in which the axis of the crankshaft is arranged on the cylinder axis and the piston pin and the crankpin are connected by a single connecting rod. The characteristics of the engine (internal combustion engine) are shown. The characteristics of the two-dot chain line are similar to those of a sine curve (broken line), and the delay side (compression stroke and exhaust stroke) and the lead side (expansion stroke and intake stroke) are symmetrical with respect to the top dead center. On the other hand, the characteristic of the present embodiment indicated by the solid line is that the period of the expansion stroke and the intake stroke is longer than the period of the compression stroke and the exhaust stroke as described above. Becomes asymmetric.

  By the way, the engine E of the present embodiment is a 4-stroke type engine, and intake, compression, combustion, and exhaust strokes are performed while the piston 3 reciprocates twice, and the intake and exhaust valves 23 and 24 are opened / closed accordingly. The As shown in FIG. 5, the first chain 32a is hung between the first sprocket 30 and the first intermediate sprocket 31a of the crankshaft 5 for opening and closing the intake and exhaust valves 23 and 24, A second chain 32 b is wound between a second intermediate sprocket 31 b provided integrally with the first intermediate sprocket 31 a and the second sprocket 33 of the camshaft 34. The first sprocket 30 is provided coupled to the end of the crankshaft 5, and the first and second intermediate sprockets 31a and 31b are provided to the right of the first sprocket 30 in the housing HSG, and the second The sprocket 33 is provided on a camshaft 34 that is rotatably provided on the side of the cylinder block 1.

  The number of teeth of the first and second sprockets 30, 33 is set to 1: 2 (via the first and second intermediate sprockets 31 a, 31 b), and the camshaft is half the rotational speed of the crankshaft 5. 34 is rotationally driven. The camshaft 34 is formed with an intake cam portion 34a and an exhaust cam portion 34b, and rollers 35b and 36b of cam followers 35 and 36 pivotally connected to the cylinder block 1 by connecting pins 35a and 36a, respectively. It is in contact with the parts 34a, 34b (see FIG. 5).

  On the other hand, rocker arms 39, 40 for operating the intake / exhaust valves 23, 24 are pivotally attached to the upper surface of the cylinder head 2 by pivot pins 39a, 40a. Push rods 37 and 38 are arranged as shown in the figure by connecting one end of the cam followers 35 and 36 to each other. The other ends of the rocker arms 39 and 40 are in contact with the tips of the intake and exhaust valves 23 and 24, and the intake and exhaust valves 23 and 24 are resisted against the biasing of the valve springs 23a and 24a by the rocking of the rocker arms 39 and 40. It can be pushed down to release it.

  In the mechanism configured as described above, the camshaft 34 is rotationally driven at a rotational speed ½ that of the crankshaft 5, and the cam followers 35 and 36 are correspondingly rotated once for each rotation of the camshaft 34 (that is, the crankshaft). Rocks up and down once every two rotations of 5). In response to this swing, the push rods 37 and 38 are reciprocated up and down to swing the rocker arms 39 and 40 via the pivot pins 39a and 40a, and the intake and exhaust valves 23 and 24 are connected to the valve springs 23a and 24a. The intake and exhaust passages 2 a and 2 b are communicated with the combustion chamber 4 by being pushed down against the bias and released. The cam portions 34a and 34b are set so that the intake valve 23 is opened during the intake stroke and the exhaust valve 24 is opened during the exhaust stroke.

  Further, a mixture of compressed air and fuel is injected from the mixture injection injector 100 into the combustion chamber 4 at a predetermined timing (so-called air assist type fuel injection), and this mixture is ignited and burned by the spark plug 21. A combustion stroke is performed. At this time, the air-fuel mixture injector 100 injects a high-concentration air-fuel mixture around the tip ignition portion 21a of the spark plug 21 to perform efficient combustion (stratified combustion) and to perform lean combustion as a whole. As a result, fuel consumption can be improved and exhaust gas can be cleaned.

  As shown in FIGS. 10 and 11, the air-fuel mixture injector 100 operates to open and close the air injection valve 116 with compressed air (hereinafter referred to as air) in a pressurized mixing chamber 134 (see FIG. 10). The fuel injection valve 146 supplies the fuel supplied to the fuel chamber 166 from the air injector 110 injected into the combustion chamber 4 through the fuel supply line 27 (see also FIG. 7) from the fuel pump P (see FIG. 11). And a fuel injector 140 that injects into the mixing chamber 134 by an opening / closing operation.

  As shown in FIG. 10, the air injector 110 includes a housing 112 that is fixed to the head cover 26 (see FIG. 1 and the like) and extends in the vertical direction, and a pipe line 114 that is formed in the housing 112 so as to extend in the vertical direction. An air injection valve 116 that is slidably movable in the pipe 114 in the vertical direction, a core 118 fixed to the top of the air injection valve 116, a spring 120 that constantly biases the core 118 upward in FIG. A coil 124 provided on the outer periphery of 118 surrounded by a resin 122 is mainly configured. The coil 124 can be energized from the control device 180 via the electric wire 126, and the energized coil 124 is excited to become an electromagnet.

  A plug member 128 is provided at the lower end of the air injection valve 116, and when the coil 124 is not energized and is not excited, the core 118 (that is, the air injection valve 116) is attached upward by the spring 120. As a result, the plug member 128 closes the air-fuel mixture injection port 115 formed at the lower end of the pipe 114 (the state shown in FIG. 10). A fuel injector mounting space 130 opened upward is formed in the upper part of the housing 112, and a nozzle portion 144 (described later) of the fuel injector 140 is fitted into the bottom of the fuel injector mounting space 130 from above. A nozzle holding member 132 for holding is provided. The internal space of the nozzle holding member 32 is a mixing chamber 134 in which the fuel injected from the fuel injector 140 and the compressed air are mixed. The mixing chamber 134 passes through an air-fuel mixture passage 136 that extends downward, and the pipe line 114. (In the internal space of the air injection valve 116).

  As shown in FIG. 11, the fuel injector 140 includes a housing 142 that is mounted in the fuel injector mounting space 130 formed in the housing 112 of the air injector 110, and a nozzle portion 144 that is provided at the lower end of the housing 142. A fuel injection valve 146 extending so as to vertically penetrate the upper wall portion 144a of the nozzle portion 144, and a core 148 fixed to the outer peripheral portion of the plunger 146a constituting the fuel injection valve 146; A spring 150 that constantly biases the plunger 146a downward, and a coil 154 that is provided on the outer periphery of the core 148 and surrounded by the resin 152 are mainly configured. The coil 154 can be energized from the control device 180 via the terminal 156, and the energized coil 154 is excited to become an electromagnet.

  A ball member 146b is attached to the lower end portion of the plunger 146a. When the coil 154 is not energized and is not energized, the core 148 is biased downward by the spring 150 (ie, the plunger 146a) to The member 146b comes into contact with the valve seat 162 of the nozzle port 160 extending vertically through the lower wall 144b of the nozzle unit 144 from above and closes the nozzle port 160 (the state shown in FIG. 11). The high-pressure fuel supplied from the fuel pump P is introduced into the housing 142 from a fuel supply port 164 provided on the side of the housing 142, and enters the fuel chamber 166 in the nozzle portion 144 via the oil passages 164a, 164b, 164c. Sent.

  In order to perform air-assist fuel injection in this way, the air-fuel mixture injector 100 includes an air injector 110 and a fuel injector 140. In addition, the compressor 50 supplies compressed air into the mixing chamber 134. have. In the mixing chamber 134, the fuel injected from the fuel injector 140 and the compressed air supplied from the compressor 50 are mixed to form a high-concentration air-fuel mixture, and this air-fuel mixture has its own internal pressure. Using the mixture injection injector 100 (from the air injector 110), it is injected into the combustion chamber 4 at a predetermined timing (detailed operation of the mixture injection injector 100 will be described later).

  As shown in FIGS. 6 and 7, the compressor 50 is configured integrally with the cylinder block 1, and includes a compressor cylinder body 51 having a cylindrical cylinder inner peripheral surface 51 a, and a compressor cylinder body 51. A compressor cylinder head 52 mounted so as to cover the upper surface, a compressor piston 53 provided in the compressor cylinder body 51 by being slidably fitted in the cylinder inner peripheral surface 51a in the axial direction, and a compressor And a scotch yoke mechanism SY for sliding and reciprocating in a state where the piston 53 is fitted to the cylinder inner peripheral surface 51a. The scotch yoke mechanism SY is provided so as to be slidable in a direction perpendicular to the cylinder shaft by fitting in a sliding hole 54a formed at the tip of a flat piston rod 54 integrally connected to the compressor piston 53. The slider 55 is configured to have an eccentric shaft 57 formed eccentrically at the tip of the compressor drive shaft 56 provided on the side of the cylinder block 10, and the eccentric shaft 57 rotates to the slider 55. It is fitted and connected freely. In addition, as shown in FIG. 8, the compressor drive shaft 56 is rotatably supported by the cylinder body 10 via bearings 58a and 58b.

  In the compressor having such a configuration, when the compressor drive shaft 56 is rotationally driven, the compressor piston 53 can be reciprocated while being in sliding contact with the cylinder inner peripheral surface 51a by the action of the scotch yoke SY. In order to rotationally drive the compressor drive shaft 56, a third sprocket 60 is provided integrally with a second sprocket 33 that is coupled to the camshaft 34, and a fourth sprocket 61 is coupled to the compressor drive shaft 56. The third chain 62 is wound around the third and fourth sprockets 60 and 61. The third and fourth sprockets 60 and 61 have the same number of teeth, and both rotate at the same rotational speed as the second sprocket 33. For this reason, the fourth sprocket 61 is rotated at a half rotational speed of the crankshaft 5, the compressor drive shaft 56 is also rotated at the same rotational speed, and the compressor piston 53 is rotated once when the crankshaft 5 is rotated twice. Make a round trip. As the compressor piston 53 is reciprocated in this way, in the cylinder space 50a (see FIG. 9) surrounded by the compressor cylinder head 52 and the compressor piston 53 in the cylinder inner peripheral surface 51a. Inhale air and compress.

  A valve plate 63 made of a thin metal plate is sandwiched between the compressor cylinder body 51 and the compressor cylinder head 52 to function as a gasket (see FIG. 9). Two intake reed valves 64 are formed in the valve plate 63 by punching in a tongue-like shape. When the compressor piston 53 moves downward, it receives a negative pressure generated in the cylinder space 50a. As shown by the two-dot chain line in FIG. 9, the outside air is allowed to be introduced from the intake hole 52a by being elastically deformed and bent. The valve plate 63 is formed with a circular hole 65 into which the convex portion 53a formed on the compressor piston 53 can be fitted.

  An exhaust poppet valve 70 is provided above the valve plate 63. As shown in FIG. 9, the exhaust poppet valve 70 includes a disc-like valve body 71 provided so as to be seated on a seating surface 52 c in a compressed air passage space 52 d formed in the compressor cylinder head 52. It is comprised from the compression spring 74 which urges | biases the valve body 71 in the direction which seats on the seating surface 52c. An air communication hole 52b is formed to communicate with the cylinder space 50a from the seating surface 52c in the compressed air passage space 52d, and the air passage hole 52b is covered by the valve body 71 in a state where the valve body 71 is seated on the seating surface 52c. Closed. The exhaust poppet valve 71 configured as described above receives the negative pressure generated in the cylinder space 50a when the compressor piston 53 is moved downward as indicated by an arrow A in FIG. The air passage hole 52b is held while being seated on the surface 52c, and the compressed air in the compressed air passage space 52d is prevented from flowing back into the cylinder space 50a.

  As can be seen from the above description, when the crankshaft 5 is rotated, this rotation is transmitted via the first to third chains 32 a, 32 b, 62, and the compressor drive shaft 56 is ½ of the crankshaft 5. The compressor piston 53 is reciprocated corresponding to the rotation of the compressor drive shaft 56. As a result, the compressor piston 53 is reciprocated once every two rotations of the crankshaft 5. When the compressor piston 53 is reciprocated in this way, the intake reed valve 64 is opened in the downward stroke of the compressor piston 53 (the stroke moving in the direction of arrow A in FIG. 9), and the cylinder is formed from the intake hole 52a. Cylinder in which external air is sucked into the space 50a and the exhaust poppet valve 70 is opened in the upward movement stroke (stroke moving in the direction of arrow B in FIG. 9) and compressed in accordance with the upward movement of the compressor piston 53. The compressed air in the space 50a is pushed into the compressed air passage space 52d. Note that the timing of pushing out the compressed air in this way is synchronized with the rotation of the crankshaft 5 as described above, and is performed in accordance with the fuel injection by the air-fuel mixture injector 100.

  When the compressor piston 53 moves up to the vicinity of the top dead center, the above-mentioned convex portion 53a formed in the compressor piston 53 is formed in the air formed in the compressor cylinder head 52 from the circular hole 65 formed in the valve plate 63. It fits in the passage hole 52b. Thereby, the air in the internal space of the air passage hole 52b is compressed by the convex portion 53a and pushed out into the compressed air passage space 52d, so that the compression dead space is reduced and the compression efficiency is increased.

  The compressed air supply pipe 75 is connected to the compressed air passage space 52d to which compressed air is supplied as described above. As shown in FIG. 7, the compressed air supply pipe 75 is connected to a compressed air supply path 76 formed in the cylinder head 12, and the compressed air supply path 76 further opens into the mixing chamber 134 described above. Yes. Further, a pressure adjusting device 78 for adjusting the pressure of the compressed air supplied from the compressor 50 into the mixing chamber 134 is connected to the compressed air supply path 76 (see FIG. 5).

  On the other hand, as shown in FIG. 8, a magnet coupling type water pump WP is provided so as to be connected to an end of the compressor drive shaft 56 opposite to the side where the eccentric shaft 57 is formed. The water pump WP includes an outer magnet 81 coupled to the compressor drive shaft 56 via a coupling member 80, an inner magnet 82 opposed to the inside of the outer magnet 81 via a separating member 84, and an inner magnet 82. And a pump blade 85 attached to the tip of the pump shaft 83. The isolation member 84 isolates the space in which the hydraulic oil in which the compressor drive shaft 56 is provided flows and the space in which the cooling water in which the pump blades 85 are provided flows. The outer magnet 81 and the inner magnet 82 constitute a non-contact type coupling mechanism and are separated by sandwiching the separating member 84, but the other follows the rotation of one by the action of the magnetic force between the two, and rotates.

  In the water pump WP, as described above, when the compressor drive shaft 56 is rotated by the rotation of the crankshaft 5 and the outer magnet 81 is rotated together with the compressor drive shaft 56, the inner magnet 82 is brought into contact therewith by the magnetic coupling action. The pump blades 85 are driven to rotate through the pump shaft 83. Thereby, engine cooling water is drawn from the water tank and discharged from the discharge port 87. A cooling water supply pipe (not shown) is connected to the discharge port 87, and this cooling water supply pipe is connected to the cooling water inlet 88 shown in FIG. 5 and is formed in the cylinder block 1 and the cylinder head 2 from here. Cooling water is supplied to the cooling water passage. Cooling water that circulates through the cooling water passage and cools the cylinder block 1 and the cylinder head 2 is sent from a cooling water outlet 89 (see FIG. 1) to a radiator via a pipe (not shown). In the water pump WP, a thermostat 86 is provided at a portion through which cooling water from the pump blade 85 to the discharge port passes (see FIG. 8).

  As shown in FIG. 5, a starter motor SM for starting the engine E is attached to the housing HSG. A starter pinion (not shown) is attached to the drive shaft of the starter motor SM, and this starter pinion is attached to the end of the crankshaft 5 via a one-way clutch (not shown). ).

  In the engine E configured as described above, when the starter motor SM is driven to start the engine E, a starter gear (not shown) is rotationally driven via a starter pinion (not shown), and the crankshaft 5 Is driven to rotate. As a result, the compressor 50 is driven as described above, and compressed air is supplied to the mixing chamber 134 in the air injector 110. At the same time, the fuel pump P is driven by the rotation of the crankshaft 5 and high pressure fuel is supplied into the fuel chamber 166 of the fuel injector 140.

  As described above, in the fuel injector 140, when the coil 154 is not energized and is not energized, the core 148 (that is, the plunger 146a) is urged downward by the spring 150, and the ball member 146b opens the nozzle port 160. When the coil 154 is energized and excited to become an electromagnet, the core 148 is attracted by the coil 154 and the plunger 146a moves upward, so that the ball member 146b moves away from the valve seat 162. Thus, the nozzle port 160 is opened. As a result, the high-pressure fuel pressurized in the fuel chamber 166 is injected from the nozzle port 160 and mixed with the compressed air in the mixing chamber 134 to generate a high-pressure concentration mixture.

  On the other hand, in the air injector 110, as described above, when the coil 124 is not energized and is not energized, the core 118 (that is, the air injection valve 116) is urged upward by the spring 120 and the plug member 128 is energized. Closes the air-fuel mixture injection port 115 at the lower end of the pipe 114, but when the coil 124 is energized and energized to become an electromagnet, the core 118 is attracted to the coil 124 and the air injection valve 116 is energized. Therefore, the plug member 128 is separated from the mixture injection port 115 and the mixture passage (the internal space of the air injection valve 116 and the mixture passage 136) is opened. As a result, the high-pressure air-fuel mixture that has been pressurized in the mixing chamber 134 is injected into the combustion chamber 4 from the air-fuel mixture injection port 115.

  After the compression stroke of the piston 3, the air-fuel mixture is ignited by the spark plug 21 and burned, and the engine E is started through the fuel / expansion stroke. As described above, the cavity 3b is provided on the upper surface of the piston 3, and the air-fuel mixture is sufficiently secured in the cavity 3b. For this reason, the air-fuel mixture is in a layered state that is very flammable during the compression stroke.

  In this way, heat loss is reduced by stratified combustion using the air-fuel mixture injector 100, so that the effect of reducing the piston speed near the top dead center leads to improvement in thermal efficiency, and the thermal efficiency of the engine E can be improved. it can. That is, as shown in FIG. 4, the period of the expansion stroke in the engine E is longer than the period of the exhaust stroke, and the lowering speed of the piston 3 corresponding to the rotation of the crankshaft 5 becomes smaller. The capacity is increased and the thermal efficiency is improved.

  Further, when the piston 3 is located at the top dead center, the direction of the first connecting rod 11 is approximately the axis L2 of the cylinder block 1 (the central axis of the space formed by being surrounded by the cylinder inner peripheral surface 1a). The dimension of the engine E in the direction of the axis L2 of the cylinder block 1 is reduced by being parallel and configured so that the direction of the second connecting rod 12 is substantially perpendicular to the axis L2 of the cylinder block 1. Can do.

  Further, since the piston 3 includes the cavity portion 3b that receives most of the air-fuel mixture, the air-fuel mixture can be sufficiently ensured in the cavity portion 3b, so that more stable stratified combustion is possible. Become.

  In the above-described embodiment, when the piston 3 is at the top dead center, the second connecting rod 12 extends in a direction perpendicular to the axis L2 of the cylinder block 1, but for example, as shown in FIG. The axis L6 of the second connecting rod 212 may extend slightly obliquely upward with respect to the direction perpendicular to the axis L2 of the cylinder block 1, and, for example, as shown in FIG. The axis L6 of the cylinder block 1 may extend slightly obliquely downward with respect to the direction orthogonal to the axis L2 of the cylinder block 1.

  In FIG. 12, since the configuration is the same as that of the engine E of the above-described embodiment shown in FIG. 2, parts other than the connecting means 210 composed of the first and second connecting rods 211 and 212 are assigned the same numbers. doing. Similarly, in FIG. 13, since the configuration is the same as that of the engine E of the above-described embodiment shown in FIG. 2, parts other than the connecting means 310 including the first and second connecting rods 311, 312 have the same number. Is attached.

  At this time, in the connecting means 210 shown in FIG. 12, when the piston 3 is at the top dead center, the position of the axis L5 of the intermediate pin 13 on the axis L2 of the cylinder block 1 is Q1, and from the axis L1 of the crankshaft 5 When S is a leg of a perpendicular line lowered to the axis L2 of the cylinder block 1, Q1 is on the lower side of S. Further, in the connecting means 310 shown in FIG. 13, when the piston 3 is at the top dead center, the position of the axis L5 of the intermediate pin 13 on the axis L2 of the cylinder block 1 is Q2, and the axis L1 of the crankshaft 5 Q2 is on the upper side of S, where S is a leg of a perpendicular line that is lowered to the axis L2 of the cylinder block 1.

  In the connecting means 210 and 310 shown in FIGS. 12 and 13, the second connecting rods 212 and 312 are disposed substantially perpendicular to the first connecting rods 211 and 311 when the piston 3 is at the top dead center. The operational effects of the above embodiment can be achieved as they are. Strictly speaking, however, in the connecting means 210 shown in FIG. 12, since Q1 is located below S, a tensile load acts on the second connecting rod 212 when the piston 3 descends from the top dead center during the expansion stroke. To do. Further, in the connecting means 310 shown in FIG. 13, since Q2 is positioned above S, a compression load is applied to the second connecting rod 312 for an instant when the piston 3 descends from the top dead center in the expansion stroke. Therefore, from the viewpoint of the strength of the second connecting rod, the arrangement of the connecting means 210 shown in FIG. 12 where a compressive load does not act on the second connecting rod is more advantageous. By adopting such an arrangement, the second connecting rod is The diameter can be reduced to contribute to weight reduction.

  Moreover, in the above-mentioned embodiment, although demonstrated using the 4-cycle engine E used for a two-wheeled vehicle as an example of the internal combustion engine which concerns on this invention, it is not restricted to this, The engine (internal combustion engine) of a four-wheeled vehicle The present invention can also be applied to a two-cycle engine (internal combustion engine).

  Furthermore, as shown in FIG. 14, a cylinder 415, a piston 416 slidably fitted in the cylinder 415, a crankshaft 419 connected to the piston 416, and a connecting rod connecting the piston 416 and the crankshaft 416. 421 and a cylinder head 412 provided at one end of the cylinder 415 and forming a combustion chamber (not shown) between the piston 416 and the cylinder head 412 disposed between the piston 416 and the crankshaft 419. In the engine E2 configured as described above, a fuel injection device (a mixture injection injector) that directly injects fuel into the combustion chamber may be provided. In this way, similarly to the engine E described above, the thermal efficiency of the engine E2 can be improved.

  FIG. 14 shows a motorcycle power unit PU including the engine E2 according to the second invention. The power unit PU includes a transmission case 411 and a cylinder head 412 fastened to the front surface of the transmission case 411. And a cylinder block 413 fastened to the front surface of the cylinder head 412 and a cover 414 fastened to the front surface of the cylinder block 413. In the following description, the left side in FIG. 14 is the front of the power unit PU. A piston 416 is slidably fitted to a cylinder 415 supported inside the cylinder block 413, and a piston pin 417 is fixed to a front end of legs 416a and 416a integrally projecting forward from the piston 416. Established. Further, a U-shaped notch 415a is formed at the front end of the cylinder 415 in order to avoid interference with the piston pin 417 when the piston 416 is at the top dead center shown in FIG.

  The crankshaft 419 supported on the mating surfaces of the cylinder head 412 and the transmission case 411 includes a pair of crankpins 419a. The rear ends of the pair of connecting rods 421 are connected to the crankpins 419a via the needle bearings 420. It is connected with. Further, the front ends of the pair of connecting rods 421 are pivotally connected to both ends of the piston pin 417 through an opening (not shown) of the cylinder head 412 and an opening (not shown) of the cylinder block 413.

  A combustion chamber (not shown) is formed in the cylinder head 412 so as to face the top surface of the piston 416, and an intake port (not shown) extending upward from the combustion chamber and an exhaust port (not shown) extending downward. Are respectively opened and closed by an intake valve 425 and an exhaust valve 426 arranged in a V shape. An ignition plug (not shown) is attached to the combustion chamber so as not to interfere with the intake valve 425 and the exhaust valve 426.

  The mission case 411 supports an intake rocker shaft 430 and an exhaust rocker shaft 431, and an intake rocker arm 432 that is swingably supported by the intake rocker shaft 430 includes an intake cam 433 and an intake valve fixed to the camshaft 428. It abuts on the stem end of 425. An intermediate portion of an L-shaped driven exhaust rocker arm 434 is swingably supported on the exhaust rocker shaft 431, one end of the driven exhaust rocker arm 434 contacts the stem end of the exhaust valve 426, and the other end is Connected to one end of the connecting rod 435. A drive exhaust rocker arm 436 independent of the intake rocker arm 432 is swingably supported on the intake rocker shaft 430, and an exhaust cam 437 fixed to the camshaft 428 is attached to the drive exhaust rocker arm 436. While abutting, the other end of the connecting rod 435 is connected.

  The rotation of the camshaft 428 is transmitted to the intake valve 425 via the intake cam 433 and the intake rocker arm 432, and the intake valve 425 is driven to open at a rate of once per two rotations of the crankshaft 419. The rotation of the camshaft 428 is transmitted to the exhaust valve 426 via the exhaust cam 437, the drive exhaust rocker arm 436, the connecting rod 435 and the driven exhaust rocker arm 434, and exhausted at a rate of once per two rotations of the crankshaft 419. The valve 426 is driven to open.

  In the engine E2 configured as described above, the cylinder head 412 is disposed at a position sandwiched between the piston 416 and the crankshaft 419. In FIG. 15, the relationship between the crank angle θ with respect to the top dead center of the engine E2 and the displacement x of the piston 416 with reference to the top dead center is indicated by a broken line. Here, the stroke between the top dead center and the bottom dead center of the piston 416 is 60 mm. As can be seen from FIG. 15, when the piston 416 is at the midpoint between the top dead center and the bottom dead center (the point where the displacement is −30 mm), the crank angle θ is an angle θb larger than 90 °. On the other hand, in the cosine curve indicated by the solid line, when the piston 416 is at the midpoint between the top dead center and the bottom dead center, the crank angle θ is 90 °.

  Thus, in the engine E2 according to the second invention, it can be seen that the line indicating the relationship of the displacement x of the piston 416 with respect to the crank angle θ (see the broken line) is located above the cosine curve indicated by the solid line. . This means that the change amount of the displacement x of the piston 416 relative to the change amount of the crank angle θ is smaller than the characteristic of the cosine curve near the top dead center of the piston.

  As described above, in order to increase the thermal efficiency of the engine E2, it is desirable to increase the isovolume during the combustion of the air-fuel mixture. For this purpose, when the piston 416 descends from the top dead center in the expansion stroke, the crank angle θ The smaller the amount of increase in the volume of the combustion chamber (not shown) with respect to the amount of increase, the higher the isovolume and the thermal efficiency. As is clear from FIG. 15, the displacement x of the piston 416 near the top dead center of the engine E2 indicated by the broken line is smaller than the displacement x of the piston of the conventional engine indicated by the chain line. That is, the descending speed and ascending speed of the piston 416 corresponding to the rotation of the crankshaft 419 near the top dead center are smaller than those of the conventional one.

  If the engine E2 according to the second aspect of the invention includes a fuel injection device that directly injects fuel into the combustion chamber, the piston 416 corresponding to the rotation of the crankshaft 419 near the top dead center. Since the lowering speed and the rising speed of the engine are smaller than the conventional ones, the heat loss is reduced by stratified combustion using the fuel injection device, and the effect of reducing the piston speed near the top dead center leads to the improvement of the thermal efficiency. The thermal efficiency of the engine E2 can be improved. Furthermore, since the ascending speed of the piston 416 can also be reduced, the fuel injection timing is advanced, fuel atomization is improved, and the thermal efficiency of the engine E2 can be further improved. In addition, if the piston 416 is configured to include a cavity portion that receives most of the air-fuel mixture, the air-fuel mixture can be sufficiently secured in the cavity portion, so that more stable stratified combustion is possible.

1 is a cross-sectional view showing a motorcycle engine, which is an example of an internal combustion engine according to the present invention, cut along a plane passing through axes of a crankshaft and a cylinder block. It is sectional drawing which shows the said engine cut | disconnected in the surface which passes along the axis line of a cylinder block, and the center of an intake / exhaust valve (it shows the state which a piston is located in a top dead center). FIG. 3 is a cross-sectional view showing a state where a piston is located at a bottom dead center in FIG. 2. It is a graph which shows the relationship between a crank angle and a piston stroke. It is a fragmentary sectional view which shows the front front side of the said engine. It is a front sectional view of a compressor provided in the engine. It is a sectional side view of the compressor. It is a plane sectional view of the above-mentioned compressor and water pump. It is a front sectional view which expands and shows the cylinder head part of the above-mentioned compressor. It is sectional drawing of an air injector. It is sectional drawing of a fuel injector. It is a sectional side view which shows the modification of the said engine. It is a sectional side view showing the 2nd modification of the above-mentioned engine. It is a sectional side view of the engine which concerns on 2nd invention. It is a graph which shows the relationship between the crank angle of the engine which concerns on 2nd invention, and piston displacement.

Explanation of symbols

E engine (internal combustion engine)
E2 Engine according to the second invention (internal combustion engine)
L2 Cylinder block axis 1 Cylinder block 2 Cylinder head 3 Piston (3a Piston pin, 3b Cavity)
4 Combustion chamber 5 Crankshaft (5a Crankpin)
DESCRIPTION OF SYMBOLS 10 Connecting means 11 1st connecting rod 12 2nd connecting rod 13 Intermediate pin 14 Link arm 15 Fixing part 19 Link mechanism 100 Air-fuel mixture injector 100 (fuel injection device)
210 Connecting means (modification)
211 First connecting rod 212 Second connecting rod 310 Connecting means (second modification)
311 1st connecting rod 312 2nd connecting rod 412 Cylinder head (another embodiment)
415 Cylinder 416 Piston 419 Crankshaft 421 Connecting rod (connecting means)

Claims (4)

A cylinder,
A piston slidably fitted into the cylinder;
A crankshaft connected to the piston;
Connecting means for connecting the piston and the crankshaft;
In the internal combustion engine in which the connecting means is configured to have a link mechanism that makes the lowering speed of the piston in accordance with the rotation of the crankshaft smaller than the rising speed of the piston,
An internal combustion engine comprising a fuel injection device that directly injects and supplies fuel into a combustion chamber of the internal combustion engine. The link mechanism is
A first connecting rod having one end pivotally connected to the piston and the other end provided with an intermediate pin;
A second connecting rod having one end pivotally connected to the intermediate pin and the other end pivotally connected to the crankshaft;
One end is pivotally connected to the intermediate pin, and the other end is provided with a fixed portion located below the crankshaft and a link arm pivotally connected.
When the piston is located at the top dead center, the direction of the first connecting rod is substantially parallel to the central axis of the cylinder, and the direction of the second connecting rod is substantially perpendicular to the central axis of the cylinder. The internal combustion engine according to claim 1, wherein the internal combustion engine is configured as follows. A cylinder,
A piston slidably fitted into the cylinder;
A crankshaft connected to the piston;
Connecting means for connecting the piston and the crankshaft;
A cylinder head provided at one end of the cylinder and forming a combustion chamber with the piston;
In the internal combustion engine configured such that the cylinder head is disposed between the piston and the crankshaft,
An internal combustion engine comprising a fuel injection device that directly injects and supplies fuel into the combustion chamber. The fuel injection device is configured to inject and supply an air-fuel mixture obtained by mixing the fuel and compressed air into the combustion chamber,
4. The internal combustion engine according to claim 1, wherein the piston includes a cavity that receives most of the air-fuel mixture injected from the fuel injection device. 5. organ.

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