JP2004036409A - Fuel injector of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To set a spray pattern for restraining the deterioration in combustibility when fuel sticks to a cylinder wall surface in a lift small area of intake valves. <P>SOLUTION: This engine is provided with the two intake valves 105 and two exhaust valves 107 in respective cylinders. A fuel injection valve 131 being a two-way valve is arranged in an intake port 130 for injecting the fuel toward the respective intake valves 105. The spray pattern of the fuel injection valve 131 striking on a shade part back face of the respective intake valves 105 is deviatively set on the exhaust valve 107 side so that the shade part outer periphery and the spray pattern have a common tangent at a point closest to the exhaust valves 107 and 107, and avoids fuel spray striking on the side close to a cylinder wall of a shade part. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel injection device for an engine, and more particularly, to a technique for improving a spray pattern of a fuel injection valve.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been known a fuel injection device having a configuration in which a fuel injection valve is disposed upstream of an intake valve to inject fuel toward the back of an umbrella portion of the intake valve during an intake stroke (Japanese Patent Application Laid-Open No. Hei 6-1994). 010807).
[0003]
[Problems to be solved by the invention]
By the way, in an engine equipped with a variable valve lift mechanism that changes the lift amount of the intake valve, when the lift amount of the intake valve is small, the flow during the intake stroke becomes strong in the outer peripheral direction of the valve. There is a problem that the fuel injected from the side easily adheres to the cylinder wall surface, resulting in deterioration of combustion.
[0004]
The present invention has been made in view of the above problems, and even if the lift amount of the intake valve is small, it is possible to suppress the fuel from adhering to the cylinder wall surface, and thereby improve the combustion performance of the engine. It is an object to provide an injection device.
[0005]
[Means for Solving the Problems]
Therefore, according to the first aspect of the present invention, the spray pattern of the fuel injection valve, which corresponds to the back of the head portion of the intake valve, is biased toward a side away from the cylinder wall surface.
According to the above configuration, the fuel spray does not impinge on the entire back surface of the umbrella portion of the intake valve, but the spray is biased toward the side of the umbrella portion rear surface away from the cylinder wall surface. Fuel is drawn into the cylinder from the side remote from the cylinder.
[0006]
Therefore, even when the lift amount of the intake valve is small and the flow during the intake stroke is strong in the outer peripheral direction of the valve, it is possible to suppress the fuel from adhering to the cylinder wall surface, thereby improving the combustibility. As a result, fuel consumption and emission can be reduced.
It should be noted that the inventions according to the second to fourth aspects also exhibit the same effects as the first aspect.
[0007]
According to the second aspect of the present invention, the spray pattern of the fuel injection valve corresponding to the back of the head of the intake valve is biased toward the center of the combustion chamber.
According to the above configuration, the fuel injected from the fuel injection valve is arranged so as to be biased toward the side near the center of the combustion chamber on the back surface of the umbrella portion of the intake valve, and mainly the side near the center of the combustion chamber of the intake valve. From the fuel is sucked into the cylinder.
[0008]
According to the third aspect of the present invention, the spray pattern of the fuel injection valve corresponding to the back surface of the head portion of the intake valve is biased to the side closer to the exhaust valve opposed to the fuel injection valve.
According to the above configuration, the fuel injected from the fuel injection valve is arranged to be biased toward the side of the umbrella portion of the intake valve that is closer to the exhaust valve opposed to the intake valve. Fuel is drawn into the cylinder from the side near the valve.
[0009]
According to the fourth aspect of the present invention, the spray pattern of the fuel injector corresponding to the back of the head of each of the two intake valves is biased toward a side closer to the adjacent intake valve.
According to the above configuration, the fuel injected from the fuel injection valve is arranged to hit the side closer to the adjacent intake valve on the back surface of the umbrella portion of the intake valve, and mainly from the side where the intake valve is adjacent. Fuel is drawn into the cylinder.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a system configuration diagram of a vehicle engine including a fuel injection device according to the present invention.
In FIG. 1, an electronic control throttle 104 for opening and closing a throttle valve 103b by a throttle motor 103a is interposed in an intake pipe 102 of an engine 101, and is provided in a combustion chamber 106 through the electronic control throttle 104 and an intake valve 105. Air is inhaled.
[0011]
The combustion exhaust gas is exhausted from the combustion chamber 106 via an exhaust valve 107, purified by a front catalyst 108 and a rear catalyst 109, and then released into the atmosphere.
The exhaust valve 107 is opened and closed by a cam 111 supported by an exhaust camshaft 110 while maintaining a constant valve lift and a valve operating angle.
On the other hand, the intake valve 105 includes a variable valve event and lift (VEL) mechanism 112 that continuously and variably controls the valve lift amount together with the operating angle, and a variable valve timing control (VTC) that continuously and variably controls the valve timing. A mechanism 113 is provided.
[0012]
A variable mechanism for changing the valve operating characteristics of the exhaust valve 107 may be provided together with the intake valve 105.
An engine control unit (ECU) 114 containing a microcomputer detects an accelerator pedal sensor APS116 such that a target intake air amount corresponding to the accelerator opening is obtained based on the opening degree of the throttle valve 103b and the operation characteristics of the intake valve 105. The electronic control throttle 104, the VEL mechanism 112, and the VTC mechanism 113 are controlled in accordance with the accelerator pedal opening APO or the like.
[0013]
In addition to the accelerator pedal sensor APS 116, the ECU 114 detects an air flow meter 115 for detecting an intake air amount Q of the engine 101, a crank angle sensor 117 for obtaining a rotation signal from the crankshaft 120, and an opening TVO of the throttle valve 103b. Detection signals are input from a throttle sensor 118, a water temperature sensor 119 that detects a cooling water temperature Tw of the engine 101, and the like.
[0014]
The ECU 114 calculates the engine speed Ne based on the rotation signal output from the crank angle sensor 117.
In addition, an electromagnetic fuel injection valve 131 is provided at the intake port 130 on the upstream side of the intake valve 105 of each cylinder. When the fuel injection valve 131 is driven to open by an injection pulse signal from the ECU 114, Fuel is injected in an amount proportional to the injection pulse width (valve opening time).
[0015]
2 to 4 show the structure of the VEL mechanism 112 in detail.
However, the structure of the mechanism for continuously variably controlling the valve lift amount and the operating angle of the intake valve 105 is not limited to those shown in FIGS.
The VEL mechanism 112 shown in FIGS. 2 to 4 includes a pair of intake valves 105, 105, a hollow cam shaft 13 (drive shaft) rotatably supported by a cam bearing 14 of the cylinder head 11, and the cam shaft. 13, two eccentric cams 15 and 15 (drive cams), which are rotatable cams, a control shaft 16 rotatably supported by the same cam bearing 14 above the cam shaft 13, and a control shaft 16 A pair of rocker arms 18, 18 rotatably supported by a control cam 16 via a control cam 17, and a pair of independent rockers arranged at the upper ends of the intake valves 105, 105 via valve lifters 19, 19. Moving cams 20 and 20 are provided.
[0016]
The eccentric cams 15, 15 and the rocker arms 18, 18 are linked by link arms 25, 25, and the rocker arms 18, 18 and the swing cams 20, 20 are linked by link members 26, 26.
The rocker arms 18, 18, the link arms 25, 25, and the link members 26, 26 constitute a transmission mechanism.
[0017]
As shown in FIG. 5, the eccentric cam 15 has a substantially ring shape and includes a small-diameter cam main body 15a and a flange portion 15b integrally provided on an outer end surface of the cam main body 15a. The camshaft insertion hole 15c is formed therethrough, and the axis X of the cam body 15a is eccentric from the axis Y of the camshaft 13 by a predetermined amount.
Further, the eccentric cam 15 is press-fitted and fixed to both sides of the cam shaft 13 which do not interfere with the valve lifter 19 via the cam shaft insertion holes 15c.
[0018]
As shown in FIG. 4, the rocker arm 18 is bent substantially in a crank shape, and a central base 18a is rotatably supported by the control cam 17.
A pin hole 18d into which the pin 21 connected to the distal end of the link arm 25 is press-fitted is formed through one end 18b protruding from the outer end of the base 18a, while the inner end of the base 18a is formed. The other end portion 18c protruding from the portion has a pin hole 18e into which a pin 28 connected to one end portion 26a of each link member 26 described later is press-fitted.
[0019]
The control cam 17 has a cylindrical shape and is fixed to the outer periphery of the control shaft 16, and the position of the axis P 1 is eccentric from the axis P 2 of the control shaft 16 by α as shown in FIG.
The swing cam 20 has a substantially horizontal U-shape as shown in FIGS. 2, 6, and 7, and the cam shaft 13 is fitted into a substantially annular base end portion 22 and is rotatably supported. A support hole 22a is formed to penetrate, and a pin hole 23a is formed to penetrate an end 23 located on the other end 18c side of the rocker arm 18.
[0020]
On the lower surface of the swing cam 20, a base circular surface 24a on the base end portion 22 side and a cam surface 24b extending in an arc from the base circular surface 24a to the end edge side of the end portion 23 are formed. The circular surface 24a and the cam surface 24b abut on a predetermined position on the upper surface of each valve lifter 19 according to the swing position of the swing cam 20.
That is, from the viewpoint of the valve lift characteristics shown in FIG. 8, the predetermined angle range θ1 of the base circle surface 24a becomes the base circle section as shown in FIG. 2, and the predetermined angle range θ2 from the base circle section θ1 of the cam surface 24b. This is a so-called ramp section, and further, a predetermined angle range θ3 from the ramp section θ2 of the cam surface 24b is set to be a lift section.
[0021]
The link arm 25 includes an annular base 25a and a protruding end 25b protruding at a predetermined position on the outer peripheral surface of the base 25a. The cam body of the eccentric cam 15 is provided at a central position of the base 25a. A fitting hole 25c rotatably fitted to the outer peripheral surface of 15a is formed, and a pin hole 25d through which the pin 21 is rotatably inserted is formed through the protruding end 25b.
[0022]
Further, the link member 26 is formed in a linear shape with a predetermined length, and the pin holes 18d of the other end 18c of the rocker arm 18 and the end 23 of the swing cam 20 are formed at both ends 26a and 26b of the circular shape. , 23a are respectively formed with pin insertion holes 26c, 26d through which the ends of the pins 28, 29, which are press-fitted, are rotatably inserted.
At one end of each of the pins 21, 28, and 29, snap rings 30, 31, and 32 that regulate the axial movement of the link arm 25 and the link member 26 are provided.
[0023]
In the above configuration, as shown in FIGS. 6 and 7, the valve lift varies depending on the positional relationship between the axis P2 of the control shaft 16 and the axis P1 of the control cam 17, and the control shaft 16 is rotated. By driving, the position of the axis P2 of the control shaft 16 with respect to the axis P1 of the control cam 17 is changed.
The control shaft 16 is configured to be rotationally driven within a predetermined rotation angle range by a DC servomotor (actuator) 121 by a configuration as shown in FIG. , The valve lift amount and the valve operating angle of the intake valve 105 continuously change (see FIG. 9).
[0024]
In FIG. 10, the DC servo motor 121 is arranged so that its rotation axis is parallel to the control shaft 16, and a bevel gear 122 is supported at the tip of the rotation shaft.
On the other hand, a pair of stays 123a and 123b are fixed to the distal end of the control shaft 16, and a nut 124 is swingably supported around an axis parallel to the control shaft 16 connecting the distal ends of the pair of stays 123a and 123b. You.
[0025]
A bevel gear 126 meshed with the bevel gear 122 is rotatably supported at the tip of a threaded rod 125 meshed with the nut 124. The rotation of the DC servomotor 121 causes the threaded rod 125 to rotate. The position of the nut 124 meshing with the shaft 125 is displaced in the axial direction of the screw rod 125, so that the control shaft 16 is rotated.
[0026]
Here, the direction in which the position of the nut 124 approaches the bevel gear 126 is a direction in which the valve lift amount decreases, and conversely, the direction in which the position of the nut 124 is away from the bevel gear 126 is a direction in which the valve lift amount increases. ing.
As shown in FIG. 10, a potentiometer type operation angle sensor 127 for detecting the operation angle of the control shaft 16 is provided at the tip of the control shaft 16, and the actual operation detected by the operation angle sensor 127 is performed. The ECU 114 performs feedback control of the DC servomotor 121 so that the angle matches the target operating angle.
[0027]
Next, the configuration of the VTC mechanism 113 will be described with reference to FIG.
However, the VTC mechanism 113 is not limited to the one shown in FIG. 11, but may be any as long as it has a configuration that continuously changes the rotation phase of the camshaft with respect to the crankshaft.
The VTC mechanism 113 in the present embodiment is a vane type variable valve timing mechanism. The VTC mechanism 113 is a cam sprocket 51 (timing sprocket) that is rotationally driven by a crankshaft 120 via a timing chain. A rotating member 53 fixed and rotatably housed in the cam sprocket 51, a hydraulic circuit 54 for rotating the rotating member 53 relative to the cam sprocket 51, and a relative position between the cam sprocket 51 and the rotating member 53; A lock mechanism 60 for selectively locking the rotational position at a predetermined position.
[0028]
The cam sprocket 51 includes a rotating portion (not shown) having a toothed portion on its outer periphery with which a timing chain (or a timing belt) meshes, and a housing disposed in front of the rotating portion and rotatably housing the rotating member 53. And a front cover and a rear cover (not shown) for closing front and rear openings of the housing 56.
[0029]
The housing 56 has a cylindrical shape with open front and rear ends, and has a trapezoidal cross section on the inner peripheral surface, and four partition portions 63 provided along the axial direction of the housing 56 at 90 ° intervals. It is protruding.
The rotating member 53 is fixed to the front end of the intake-side camshaft 14, and is provided with four vanes 78a, 78b, 78c, 78d at 90 ° intervals on the outer peripheral surface of the annular base 77.
[0030]
The first to fourth vanes 78a to 78d each have a substantially inverted trapezoidal cross section, are arranged in recesses between the partition portions 63, and separate the recesses back and forth in the rotation direction. An advance side hydraulic chamber 82 and a retard side hydraulic chamber 83 are formed between both sides and both side surfaces of each partition 63.
The lock mechanism 60 is configured such that the lock pin 84 engages with an engagement hole (not shown) at the rotation position (reference operation state) of the rotation member 53 on the maximum retard side.
[0031]
The hydraulic circuit 54 has two systems: a first hydraulic passage 91 that supplies and discharges hydraulic pressure to the advance hydraulic chamber 82 and a second hydraulic passage 92 that supplies and discharges hydraulic pressure to the retard hydraulic chamber 83. The supply passage 93 and the drain passages 94a and 94b are connected to the two hydraulic passages 91 and 92 via electromagnetic switching valves 95 for switching the passages.
[0032]
The supply passage 93 is provided with an engine-driven oil pump 97 for pumping oil in an oil pan 96, while the downstream ends of the drain passages 94 a and 94 b communicate with the oil pan 96.
The first hydraulic passage 91 is connected to four branch passages 91 d which are formed substantially radially in the base 77 of the rotating member 53 and communicate with the advance hydraulic chambers 82. It is connected to four oil holes 92d opening to the retard side hydraulic chamber 83.
[0033]
In the electromagnetic switching valve 95, an internal spool valve body controls relative switching between the hydraulic passages 91 and 92, the supply passage 93, and the drain passages 94a and 94b.
The ECU 114 controls the amount of energization to the electromagnetic actuator 99 that drives the electromagnetic switching valve 95 based on a duty control signal on which a dither signal is superimposed.
[0034]
For example, when a control signal (OFF signal) having a duty ratio of 0% is output to the electromagnetic actuator 99, the hydraulic oil pumped from the oil pump 47 is supplied to the retard hydraulic chamber 83 through the second hydraulic passage 92. At the same time, the hydraulic oil in the advance hydraulic chamber 82 is discharged from the first drain passage 94 a into the oil pan 96 through the first hydraulic passage 91.
[0035]
Accordingly, the internal pressure of the retard side hydraulic chamber 83 becomes high, and the internal pressure of the advance side hydraulic chamber 82 becomes low, and the rotating member 53 rotates to the maximum retard side via the vanes 78a to 78b. The opening period (opening timing and closing timing) of the intake valve 105 is delayed.
On the other hand, when a control signal (ON signal) having a duty ratio of 100% is output to the electromagnetic actuator 99, the hydraulic oil is supplied into the advance hydraulic chamber 82 through the first hydraulic passage 91, and the retard hydraulic pressure is also supplied. The hydraulic oil in the chamber 83 is discharged to the oil pan 96 through the second hydraulic passage 92 and the second drain passage 94b, and the pressure in the retard hydraulic chamber 83 becomes low.
[0036]
For this reason, the rotating member 53 rotates to the maximum advance side via the vanes 78a to 78d, whereby the opening period (opening timing and closing timing) of the intake valve 105 is shortened.
Incidentally, the variable valve timing mechanism is not limited to the vane type described above, and as disclosed in JP-A-2001-041013 and JP-A-2001-164951, friction braking of an electromagnetic clutch (electromagnetic brake) is performed. A variable valve timing mechanism configured to change the rotation phase of the camshaft with respect to the crankshaft, or a variable valve timing mechanism that operates a helical gear by hydraulic pressure disclosed in Japanese Patent Application Laid-Open No. 9-195840 may be used.
[0037]
Next, control of the electronic control throttle 104, the VEL mechanism 112, and the VTC mechanism 113 by the ECU 114 will be described with reference to block diagrams of FIGS.
The target volume flow ratio calculation unit 301 calculates the target volume flow ratio TQH0ST (target intake air amount) of the engine 101 as follows.
[0038]
First, while calculating the required air amount Q0 corresponding to the accelerator opening APO and the engine rotation speed Ne, the ISC required air amount QISC (idling required air amount) required by the idle rotation speed control (ISC) is calculated.
Then, the sum of the required air amount Q0 and the ISC required air amount QISC is obtained as a total required air amount Q (Q = Q0 + QISC), and this is divided by the engine speed Ne and the effective exhaust amount (total cylinder volume) VOL #. Then, the target volume flow ratio TQH0ST (TQH0ST = Q / (Ne · VOL #)) is calculated.
[0039]
The VEL target angle calculation unit 302 calculates a target operating angle TGVEL (target lift amount) of the control shaft 16 in the VEL mechanism 112 based on the target volume flow ratio TQH0ST and the engine rotation speed Ne.
The VEL mechanism 112 is controlled based on the target operation angle TGVEL.
Here, as the target volume flow ratio TQH0ST is larger and the engine rotation speed Ne is higher, the lift amount is set to a target operation angle where the lift amount is larger, and the target volume flow ratio TQH0ST is smaller and the engine rotation speed Ne is lower. In the region, the target operating angle TGVEL is set such that the closing timing of the intake valve 105 is before the bottom dead center.
[0040]
However, due to the minimum limit of the lift amount, a lift amount larger than the required value corresponding to the target volume flow rate ratio TQH0ST is set on the low load / low rotation side. This excess amount will be described later. Is corrected by the throttle control of the throttle valve 103b.
In the present embodiment, it is assumed that the lift amount of the intake valve 105 increases as the operating angle of the control shaft 16 increases.
[0041]
Further, the VTC target angle calculation unit 303 calculates a target phase angle TGVTC (target advance amount) in the VTC mechanism 113 based on the target volume flow ratio TQH0ST and the engine rotation speed Ne.
The VEL mechanism 113 is controlled based on the target phase angle TGVTC (target advance angle).
[0042]
Here, as the target volume flow ratio TQH0ST is larger and the engine speed Ne is higher, the target valve timing is retarded.
The target operating angle TGVEL is input to the valve total opening area calculation unit 304, where it is converted into the total opening area of the intake valve 105 when the VEL mechanism 112 is controlled based on the target operating angle TGVEL.
[0043]
The total opening area is an integral value of the valve opening area during the opening period of the intake valve 105.
The total opening area of the intake valve 105 is output to a multiplier 312. The multiplier 312 multiplies the total opening area by a correction coefficient calculated by a VEL opening area rotation correction calculation unit 313, and obtains an effective opening area TVELAA0. Is output as
[0044]
The VEL opening area rotation correction calculation unit 313 sets a larger correction coefficient (≧ 1.0) as the engine rotation speed Ne is higher.
In the VEL mechanism 112 according to the present embodiment, as the engine speed Ne increases, the valve lift tends to be larger than the target due to the inertial force. Accordingly, the valve lift is calculated based on the target operating angle TGVEL and the target phase angle TGVTC. An error occurs between the actual opening area and the actual opening area.
[0045]
Therefore, the VEL opening area rotation correction calculation unit 313 corrects the opening area of the intake valve 105 to increase the opening area in response to the tendency that the valve lift becomes larger than the target as the engine rotation speed Ne becomes higher. Set the coefficient.
The flow rate loss correction coefficient calculation unit 314 calculates a flow rate loss coefficient CD based on the target operating angle TGVEL (target valve lift amount).
[0046]
Then, the multiplier 315 multiplies the effective opening area TVELAA0 by a flow loss coefficient CD to perform correction corresponding to a difference in flow loss due to the valve lift amount.
The effective opening area TVELAA0 corrected by the flow rate loss coefficient CD is converted by the dividers 316 and 317 by the effective displacement (total cylinder volume) VOL # and the engine rotation speed Ne into a state quantity AANV. Then, the state quantity AANV is converted by the conversion unit 318 into a volume flow ratio TQH0VEL of the intake valve 105.
[0047]
The volume flow ratio TQH0VEL of the intake valve 105 is a value on the assumption that the throttle valve 103b is fully open.
The divider 319 calculates the volume flow ratio QH0 required for the throttle valve 103b to obtain the target volume flow ratio TQH0ST by dividing the target volume flow ratio TQH0ST by the volume flow ratio TQH0VEL.
[0048]
The volume flow ratio QH0 required for the throttle valve 103b is converted into a state quantity AANV by a converter 320, and further multiplied by multipliers 321 and 322 by an effective displacement (total cylinder volume) VOL # and an engine rotation speed Ne. Thus, the opening area AA required for the throttle valve 103b is converted.
Then, the opening area AA is converted into an angle (opening) of the throttle valve 103b by the conversion unit 323, and the angle is output as a target angle TGTVO, and the electronic control throttle 104 is controlled based on the target opening TGTVO. Is done.
[0049]
FIGS. 15 to 20 are diagrams showing spray patterns of the fuel injection valve 131 in the engine 101. FIG.
The fuel injection valve 131 is a two-way injection valve that injects toward the back of the head of each intake valve 105, 105, and is provided one for each cylinder.
The spray pattern of the fuel injection valve 131 is set to one of FIGS.
[0050]
In the example shown in FIG. 15, the spray pattern hitting the back of the umbrella of each intake valve 105, 105 has a substantially circular shape having a diameter of about half the umbrella diameter, and connects the center of the umbrella of each intake valve 105. The spray pattern is set so as to be inscribed on the outer periphery of the umbrella so that the spray pattern has a common tangent at the intersection of the lines.
That is, in the configuration shown in FIG. 15, the spray pattern that strikes the back of the umbrella portion of each intake valve 105 is set so as to be biased toward the side closer to the other adjacent intake valve 105.
[0051]
The example shown in FIG. 16 is different from the spray pattern shown in FIG. 15 in that the shape of the spray pattern corresponding to the back of the umbrella portion of the intake valves 105 and 105 is changed to an elliptical shape longer in the direction connecting the fuel injection valve 131 and the cylinder center. An example is shown below.
Also, in the example shown in FIG. 17, the spray pattern corresponding to the back of the umbrella portion of each intake valve 105 is biased toward the side closer to the other adjacent intake valve 105, similarly to the spray pattern shown in FIG. 15 or FIG. In the example shown in FIG. 17, the line that is orthogonal to the cylinder radial direction and passes through the center of the intake valves 105 and 105 intersects the outer periphery of the umbrella portion, and is long in the tangential direction of the umbrella portion. The elliptical spray pattern is configured to be inscribed in the outer periphery of the umbrella.
[0052]
On the other hand, the example shown in FIG. 18 is common in that the spray pattern hitting the back of the umbrella of each intake valve 105 is substantially circular having a diameter of about half of the umbrella, and closest to the center of the combustion chamber. The spray pattern is set to be inscribed in the outer periphery of the umbrella so as to have a tangent line.
That is, in the configuration shown in FIG. 18, the spray pattern hitting the back of the head of each intake valve 105, 105 is set so as to be biased toward the center of the combustion chamber.
[0053]
The example shown in FIG. 19 is different from the spray pattern shown in FIG. 18 in that the shape of the spray pattern corresponding to the back of the umbrella of the intake valves 105 and 105 is an elliptical shape that is long in the tangential direction of the umbrella. is there.
Further, in the example shown in FIG. 20, the spray pattern that strikes the back of the head of each intake valve 105, 105 is substantially circular having a diameter of about half the diameter of the head, and each of the intake patterns is extended in the direction in which the intake port extends. The spray pattern is set so as to be inscribed in the outer periphery of the umbrella portion so as to have a common tangent at a point closest to the exhaust valves 107, 107 facing the valves 105, 105.
[0054]
That is, in the configuration shown in FIG. 20, the spray pattern that strikes the back of the head of each intake valve 105, 105 is set so as to be biased toward the side closer to the exhaust valve that is opposed to it.
According to the above spray pattern, in any case, the fuel is sucked into the cylinder from the side of the intake valve 105 that is away from the cylinder wall surface, because it hits the back surface of the umbrella portion in a direction away from the cylinder wall surface.
[0055]
When the lift amount of the intake valve 105 is small, as shown in FIG. 21, the flow during the intake stroke becomes a strong flow toward the outer periphery of the valve. However, according to the spray pattern, the fuel enters the cylinder from the side far from the cylinder wall. Since the fuel is sucked, it is possible to prevent the fuel from adhering to the cylinder wall surface, improve the combustibility, and reduce the fuel consumption and the emission.
[0056]
Although any of the spray patterns shown in FIGS. 15 to 20 may be selected, the optimum spray pattern varies depending on the shape of the combustion chamber and the shape of the valve. Just choose.
The fuel injection timing by the fuel injection valve 131 is in a low load region where the lift amount of the intake valve 105 is equal to or less than a predetermined value (for example, a region where the closing timing of the intake valve 105 is set before BDC as shown in FIG. 22). Then, as shown in FIG. 23, the injection period is substantially synchronized with the opening period of the intake valve 105 (so that the injection start timing and the injection end timing are respectively synchronized with the valve opening timing and the valve closing timing of the intake valve). , The injection timing is set.
[0057]
By setting the injection timing as described above, the fuel injected from the fuel injection valve 131 is atomized by the strong intake flow in the low lift state, and the fuel is gradually sucked into the cylinder during the intake stroke. Accordingly, a uniform air-fuel mixture can be formed in the cylinder in a low load region.
If the fuel is injected before the opening timing of the intake valve 105, the fuel that has accumulated on the upstream side of the intake valve 105 will flow into the cylinder at once immediately after the opening of the intake valve 105. Although not uniform, by injecting fuel continuously while the intake valve 105 is open, a uniform mixture can be formed even in a low load region.
[0058]
On the other hand, in a region where the lift amount of the intake valve 105 exceeds a predetermined value (high load region), fuel is injected before the intake valve 105 is opened.
In the above-described embodiment, two intake valves 105 are provided for each cylinder. However, even in an engine in which only one intake valve 105 is provided for each cylinder, it is possible to use a spray that strikes the back of the head of each intake valve 105. The same effect can be obtained by setting the pattern so as to be biased toward the center of the combustion chamber, or by biasing the pattern toward the side closer to the exhaust valve opposed to the combustion chamber.
[0059]
Further, technical ideas other than the claims that can be grasped from the above embodiment will be described below together with their effects.
(A) The fuel supply device for an engine according to any one of claims 1 to 3, further comprising a variable valve lift mechanism for changing a lift amount of the intake valve, wherein the lift amount of the intake valve is equal to or less than a predetermined value. The injection timing of the fuel injection valve is set so that the injection period of the fuel injection valve is substantially synchronized with the opening period of the intake valve.
[0060]
According to the above configuration, in the configuration in which the fuel is prevented from adhering to the cylinder wall surface by setting the spray pattern, in a region where the lift amount of the intake valve is controlled to be equal to or less than a predetermined value, the injection start timing and the injection end timing are set to the intake valve timing. The injection timing is set so as to be synchronized with the valve opening timing and the valve closing timing, respectively.
[0061]
Therefore, the fuel atomized by the strong intake flow due to the low lift can be gradually sucked into the cylinder to form a uniform air-fuel mixture.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of an engine.
FIG. 2 is a sectional view showing a VEL mechanism (variable valve lift mechanism) (a sectional view taken along line AA in FIG. 3).
FIG. 3 is a side view of the VEL mechanism.
FIG. 4 is a plan view of the VEL mechanism.
FIG. 5 is a perspective view showing an eccentric cam used in the VEL mechanism.
FIG. 6 is a cross-sectional view (a cross-sectional view taken along the line BB in FIG. 3) illustrating the operation of the VEL mechanism during a low lift.
FIG. 7 is a cross-sectional view (a cross-sectional view taken along the line BB of FIG. 3) illustrating the operation of the VEL mechanism during a high lift.
FIG. 8 is a valve lift characteristic diagram corresponding to a base end surface and a cam surface of a swing cam in the VEL mechanism.
FIG. 9 is a characteristic diagram of valve timing and valve lift of the VEL mechanism.
FIG. 10 is a perspective view showing a rotation drive mechanism of a control shaft in the VEL mechanism.
FIG. 11 is a longitudinal sectional view showing a VTC mechanism.
FIG. 12 is a block diagram showing details of intake air amount control.
FIG. 13 is a block diagram showing details of intake air amount control.
FIG. 14 is a block diagram showing details of intake air amount control.
FIG. 15 is a state diagram showing a spray pattern of a fuel injection valve.
FIG. 16 is a state diagram showing a spray pattern of a fuel injection valve.
FIG. 17 is a state diagram showing a spray pattern of a fuel injection valve.
FIG. 18 is a state diagram showing a spray pattern of a fuel injection valve.
FIG. 19 is a state diagram showing a spray pattern of a fuel injection valve.
FIG. 20 is a state diagram showing a spray pattern of a fuel injection valve.
FIG. 21 is a state diagram showing a difference in a flow direction in a lift amount.
FIG. 22 is a diagram showing a low lift state of an intake valve.
FIG. 23 is a diagram showing a correlation between lift characteristics of an intake / exhaust valve and injection timing.
[Explanation of symbols]
101 engine, 104 electronic control throttle, 105 intake valve, 107 exhaust valve, 112 VEL mechanism, 113 VTC mechanism, 114 engine control unit (ECU), 115 air flow meter, 116 accelerator pedal sensor, 117: crank angle sensor, 118: throttle sensor, 119: water temperature sensor, 120: crankshaft, 130: intake port, 131: fuel injection valve

Claims (4)

In an engine fuel injection device having a fuel injection valve provided upstream of an intake valve,
A fuel injection device for an engine, wherein a spray pattern of the fuel injection valve, which hits the back surface of the head portion of the intake valve, is biased toward a side away from a cylinder wall surface. In an engine fuel injection device having a fuel injection valve provided upstream of an intake valve,
A fuel injection device for an engine, wherein a spray pattern of the fuel injection valve, which hits a back surface of the head portion of the intake valve, is biased toward a center of a combustion chamber. In an engine fuel injection device having a fuel injection valve provided upstream of an intake valve,
A fuel injection device for an engine, wherein a spray pattern of the fuel injection valve, which hits the back surface of the head portion of the intake valve, is biased toward a side closer to the exhaust valve facing the intake valve. In a fuel injection device for an engine in which two intake valves are provided for each cylinder and a fuel injection valve is provided upstream of the two intake valves,
A fuel injection device for an engine, wherein the spray patterns of the fuel injection valves, which respectively correspond to the heads of the two intake valves, are biased toward a side closer to the adjacent intake valves.

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