Patent Application
20180209365
The present invention relates to a control device for reducing variations among individual fuel injection devices for feeding fuel to an internal combustion engine.
As a method of driving a fuel injection device of a conventional direct-injection internal combustion engine, an amount of injection required by the internal combustion engine is injected on the basis of a preset drive current profile and a drive pulse Ti of the fuel injection valve. However, as requirements and regulations on exhaust gas are tightened, the flow rates vary with the individual properties of the fuel injection devices even when the same drive current profile and drive pulse Ti are given. Thus, a method of reducing such variations has been proposed.
For example, PTL 1 proposes a drive control device of an electromagnetic valve for controlling a flow rate of fluid, the drive control device of an electromagnetic valve being characterized by including a terminal voltage detection means for detecting a terminal voltage of a solenoid of the electromagnetic valve, a filtering means for extracting a particular frequency component from a detection signal of the terminal voltage obtained immediately after stoppage of current application to the solenoid, and an estimation means for estimating seating timing at which a valve element of the electromagnetic valve is seated on a valve seat on the basis of the particular frequency component.
PTL 1: JP 2014-234922 A
One of the causes of variations in flow rate property of fuel injection devices is a bouncing caused when an anchor collides with and bounces off a core. In order to reduce a difference among the individual flow rate properties of the fuel injection devices, it is desirable that the momentum of the rising anchor be adjusted according to a set spring force to reduce a bouncing and synchronize the operations of the anchors. For this purpose, a set spring force needs to be estimated. In recent years, as described in Background Art, there have been made many inventions in which the valve closure completion timing of a valve of a fuel injection device is detected to correct the driving of the fuel injection device. In general, when a set spring force is strong, valve closure completion timing becomes earlier, and when a set spring force is weak, valve closure completion timing becomes later. Therefore, the valve closure completion timing correlates with the set spring force. When the set spring force is estimated from the valve closure completion timing on the basis of the correlation, the stroke of the fuel injection device is a disturbance of the estimation. When the stroke is longer, the valve closure completion time becomes later even when the set spring force is the same.
It is an object of the present invention to reduce the influence of stroke during estimation of a set spring force.
In order to solve the aforementioned problem, a control device of a fuel injection device of the present invention is characterized by consisting of an inflexion point extraction filter for filtering a drive voltage of a solenoid to extract inflexion points and a means of correcting a drive current on the basis of timing of a later inflexion point of the extracted inflexion points.
When the fuel injection valve is closed, two inflexion points appear in a solenoid drive voltage: one is when the valve element reaches the valve seat and the other is when the anchor collides with the stopper. The time at which the faster inflexion point of the inflexion points appears, i.e., the time at which the valve element reaches the valve seat, is subjected to the set spring force and the influence of the stroke, so that the time becomes later when the stroke is longer. Regarding movement between the two inflexion points, the valve element is accelerated over a long time when the stroke is longer. Therefore, the initial velocity becomes faster, so that the required time is shortened. Thus, at the time of the second inflexion point, i.e., the time at which the anchor reaches the stopper, the influence of the stroke is offset, enabling high-precision estimation. of the set spring force. Thus, the momenta of the rising anchor and valve element during valve opening can be homogenized by being corrected according to the set spring force, thereby enabling a reduction in difference among the individual flow rate properties.
Air is filtered with an air cleaner 101, and the flow rate is adjusted by a throttle 103. The air passes through a collector 104 and an intake port 105, and flows into the cylinder 106. An airflow sensor 102 is present between the air cleaner 101 and. the throttle 103, and measures the amount of air introduced into the internal combustion engine. Fuel a fuel tank 111 is delivered to a low-pressure pipe 113 by a low-pressure pump 112. The fuel of the low-pressure pipe 113 is delivered to a high-pressure pipe 115 by a high-pressure pump 114. The fuel in the high-pressure pipe 115 is maintained at high pressure. The high-pressure pipe 115 is provided with fuel injection device 116. When current is applied to the solenoid in the fuel injection device 116, the fuel injection valve is opened and the fuel is injected while the valve is open.
The interior of the housing 201 is filled with the fuel. When current is applied to the solenoid 203, the anchor 205 is attracted to the solenoid 203 and a lower end of the valve element 204 is moved away from the valve seat 206, so that the fuel is injected through an injection hole 209, which is formed through the valve seat 206 and is previously blocked by the valve element 204. In addition, a stopper 211 is fixed to the valve element 204 or the housing 201. When the valve element is in a valve-closed state, the anchor 205 is pressed against the stopper 211 by a zero spring 210.
The fuel injection device configured in the above manner is controlled by a control device illustrated in
The operation of controlling the fuel injection valve with the control device is described in conjunction with
There is a gap between the initial position of the anchor 205, which is pressed against the stopper 211 by the force of the zero spring 210, and the protrusion of the valve element 204. After the anchor 205 is moved in the gap, the valve element 204 starts being lifted by the anchor 205. At this time, the fuel starts flowing through the injection hole 209 (time t3).
When the time Tp stored in the setting value memory 321 elapses after the current starts being applied to the solenoid at the time t1, the switch 303 and the switch 301 are turned OFF (time t4). Normally, this timing is reached before the anchor 205 collides with the core 202. This is to prevent the momentum of collision between the anchor 205 and the core 202 from being greater than necessary. When the switches 303 and 301 are turned OFF, the current, which previously flows into the GND through the switch 303, passes through the diode 308 and flows into the capacitor 309, so that the voltage of the LOW-side terminal of the solenoid 203 becomes greater. Specifically, as indicated between t4 and t5 of the graph of voltage of
When the time T2 stored in the. setting value memory 322 elapses after the switches 301 and 303 are canceled at the time t4, the switch 302 and the switch 303 are turned ON to apply a battery voltage Vbat to the solenoid 203 (time t5). Thus, a state where the valve element 204 and the anchor 205 are in contact with the core 202 is maintained. In addition, at this time, the current flowing into the solenoid 203 is measured from the voltage generated in the shunt resistor 304, and the switch 302 is turned ON and OFF so that the current value corresponds to the value Ih stored in the setting value memory 323.
In synchronization with falling of the Ti pulse, the switches 302 and 303 are turned OFF (time t6). Then, the current is rapidly attenuated and the magnetic attractive force is attenuated. The valve element 204 and the anchor 205 are pressed by the force of the set spring 207 and start moving in the direction of the valve seat 206. In addition, at this time, during the attenuation of the current, the current flows into the capacitor 309. Therefore, a reverse voltage is applied to the solenoid 203. When the current is converged to zero, the voltage gradually approaches zero. Eventually, the valve element 204 reaches the valve seat 206, and the fuel flowing through the injection hole is stopped (time t7).
The valve element 204 and the valve seat 206 are elastic. Therefore, even after the valve element 204 reaches the valve seat 206, the valve element 204 continues moving in the direction of the valve seat 206. However, upon movement to some extent, the elastic deformation of the valve element 204 and the valve seat 206 starts returning to the original state. At this time, the anchor 205 moves away from the valve element and continues moving in the direction of the valve seat 206 by inertia (time t8). Until the time t8, the force of the set spring 207 and the force of the fuel pressure are applied to the anchor 205 via the valve element 204. However, after the time t8, such forces are not applied as the anchor 205 moves away from the valve element 204. Therefore, the acceleration of the anchor 205 is sharply reduced. When the acceleration of the anchor 205 is changed, the back electromotive force generated in the solenoid 203 is changed by the movement of the anchor 205, so that an inflexion point is generated in the voltage of the solenoid 203.
The anchor 205, even after moving from the valve element 204, continues moving in the direction of the valve seat 206 by inertia, but eventually collides with the stopper 211. This collision rapidly changes the acceleration of the anchor 205. Therefore, the back electromotive force generated in the solenoid 203 is changed, and an inflexion point is generated in the voltage of the solenoid (time t9).
Heretofore, the operation of controlling the fuel injection device with the control device has been described in conjunction with
With such a mechanism, the fuel injection valve is controlled and injects the fuel in an amount corresponding to the width of the drive pulse Ti given. It is desirable that the amount of air introduced into the internal combustion engine and the amount of fuel are at a certain ratio for efficient action of an exhaust catalyst. Therefore, an amount of air Qa measured by the airflow sensor is divided by an engine rotation rate Nang to obtain an intake amount per rotation Qa/Neng, which is divided by a target air-fuel ratio λ to obtain a value Qa/Neng/λ, and a value proportional to the value Qa/Neng/λ is defined as a pulse width Ti.
However, there are variations among individual fuel injection devices. Even when the same drive pulse Ti is added, there are variations in amount of fuel injected from the fuel injection devices mounted on respective cylinders, so that some cylinders have a rich air-fuel ratio and some cylinders have a lean air-fuel ratio.
The flow rate properties of typical fuel injection valves vary in the manner illustrated in
Switching patterns, current, valve behaviors and flow rate properties in the case where the same drive current is applied to three fuel injection devices INJ C, INJ B, INJ A having weak, average, and strong spring forces, respectively, by means of the drive device illustrated in
Upon reaching the time Tp, the switch control means 312 turns all the switches OFF and applies a reverse voltage to the solenoid 203. Then, the current flowing into the solenoid 203 is rapidly converged to zero. The magnetic attractive force Fmag generated by the solenoid 203 is gradually reduced. When the Fmag is smaller than the sum of the force Fsp of the set spring 207 and the fuel pressure Fpf, the valve shifts from rising to falling. This timing depends on the level of Fsp+Fpf. Therefore, one having a large set spring force Fsp quickly shifts from rising to falling (Tpa) and one having a small Fsp shifts late (Tpc).
The valve shifting from rising to falling when the drive current is canceled continues falling until current is again applied at Th. When the time reaches the sum Th of the time Tp and T2 stored in the setting value memories 321 and 322, respectively, the switch 303 is turned ON and the switch 301 is turned OFF, and the switch 302 is turned ON and OFF so that the current falls within a certain range from Ih stored in the setting value memory 323. Thus, at a certain time, the magnetic attractive force again exceeds Fsp+Fpf. This time becomes later when Fsp is larger (Tha) and is earlier when it is smaller (Thc). At this timing, the valve again starts rising.
In addition, the velocity of the rising valve increases depending on the exceeding amount of the period attractive force of Ih over Fsp+Fpf. Therefore, when Ih is the same, the rising velocity is faster when the spring force is smaller, and the rising velocity is later when the spring force is larger. The valve, which has started rising, eventually reaches full lift and maintains full lift until the drive pulse is canceled.
Furthermore, when the drive pulse Ti is canceled, the valve element reaches the valve seat at time Tb1a, which is the earliest, in the INJA having the strongest spring force, and the valve element reaches the valve seat at time Tb1c, which is the latest, in the INJC having the weakest spring force. As de scribed above, the valve behavior varies with spring force. As a result, as illustrated in the lower drawing of
A procedure of studying the level of spring force is described in conjunction with
Incidentally, although
The reason why the relationship of the sequence of the level of the set spring force Fsp, which is not maintained at Tb1, is maintained at Tb2 is described in conjunction with
In addition, from a different point of view, when the stroke is large, the movement distance of the valve element to the valve seat from the valve closure start becomes longer, and Tb1 is increased. However, the distance from Tb1 to Tb2 does not affect the stroke. Furthermore, the valve element and the anchor have a fast velocity at Tb1 when the stroke is longer. Therefore, the movement time from Tb1 to Tb2 is short. As described above, when Tb2−Tb1 is added to Tb1, the influence of the stroke is offset, enabling a reduction in influence of the stroke during estimation of Fsp.
Thus, as illustrated in
In addition, instead of choosing the timing of the later inflexion point, a control device of a fuel injection device characterized by consisting of an incorporation means 1001 for reading a drive voltage of a solenoid, an inflexion point extraction filter 1002 for filtering the drive voltage to highlight inflexion points, a means 1005 of calculating a temporal difference between a later inflexion point and an earlier inflexion point of the extracted inflexion points, and a drive current correction means 1004 for correcting the parameters Tp, T2, Ih of the setting value memories 321, 322, 323 illustrated in
In addition, in other words, a control device of a fuel injection device for controlling current/voltage applied to a solenoid of the fuel injection device on the basis of drive current parameters to control opening and closing of the fuel injection valve so as to control fuel injection property, characterized in that the drive current parameters are corrected on the basis of a later inflexion point of the two inflexion points appeared in a drive voltage of a solenoid or a temporal difference between a later inflexion point and an earlier inflexion point may be used.
Thus, the following effect is obtained when a later inflexion point of the two inflexion points of a solenoid drive voltage or a temporal difference between a later one and an earlier one is used: The influence of variations in stroke during estimation of a set spring force can be reduced, which is used to correct the drive current parameters to synchronize the operations of the fuel injection valves and homogenize the fuel injection properties.
A specific action and effect of correcting the parameters of drive current are described in “Addition of Tp correction means”, “Addition of Th correction means”, and “Addition of Ih correction means” below. In addition, when the present invention is carried out, regarding the two inflexion points in a solenoid drive voltage,
The action and effect are described, for example, in the case where Tp is corrected.
<Addition of Tp Correction Means>
As illustrated in
<Addition of Th Correction Means>
As illustrated in the upper drawing of
In this way, the flow rate properties are as illustrated in the lower drawing
<Addition of Ih Correction Means>
Therefore, as illustrated in the upper drawing of
As described above, when the three parameters Tp, T2, Ih are corrected on the basis of the detected Tb2 according to the set spring force, the valve behaviors are synchronized, so that the flow rate properties are also homogenized. In this way, the fuel injection devices can be used in a range up to line Qmin of the flow rate property illustrated in the lower drawing of
<Method of Extracting a Later Peak from Filter Output>
In the present example, the time of a later peak specified from a filter output. Here, a means of specializing the time of a later inflexion point from a filter output is described. As illustrated in
Regarding a signal illustrated in
In this case, when
U(t−2)<u(t−1) and u(t−1)>u(t)
is established, u(t−1) is determined to be a peak. When it is determined to be a peak, the time t−1 at which the peak is made and the peak value u(t−1) are written into the peak memory as T(0) and U(0), respectively.
Next, when
U(t−2)<u(t−1) and u(t−1)>u(t)
is again established, this is also determined to be a peak. The time t1 at which the peak is made and the peak value u(t−1) are written into the peak memory as T(1) and U(1), respectively. This is repeated to the end of the detection section. Upon reaching the end of the detection section, the peak selection means outputs T(1) as a later peak time.
In addition, a peak time difference T(1)−T(0) may be chosen. A later peak time or a difference in peak time is used so that the drive current correction means 1004 of
Another conceivable configuration is described below. As illustrated in
A signal illustrated in
Thus, the rising peak extraction means 1502 searches a maximum value only when the output of the moderation filter 1501 rises, and the falling peak filter 1503 searches a maximum value only when the output of the moderation filter 1501 falls. In this way, the two peak extraction means are provided, enabling separate identification of the first peak and the second peak.
The time of the later peak and a difference in peak time, which are searched by the two extraction means, correlates with the set spring force. The drive current correction means 1004 of
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-151456 | Jul 2015 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/071202 | 7/20/2016 | WO | 00 |
