The present disclosure relates to a fuel injection controller and a fuel injection system. In the fuel injection controller or the fuel injection system, an injection state of fuel such as an injection start time point or an injection amount is controlled by controlling an energization of a coil of a fuel injector.
JP-2012-177303A describes that a controller relates to a fuel injector injecting fuel by a lift-up (valve-opening operation) of a valve body according to an electromagnetic attractive force generated by an energization of a coil. An opening time point of the valve body and an opening time period are controlled by controlling an energization start time point of the coil and an energization time period of the coil, and then an injection start time point and an injection amount are controlled.
As shown in
Thus, at a time point t20 that the coil current reaches the first target value I1, a duty control corresponding to a current-stabilizing control controls a voltage to be applied to the coil to decrease the coil current so that the coil current becomes a second target value I2 that is less than the first target value I1.
The higher a temperature of the coil becomes, the greater a resistance of the coil becomes. In this case, as dotted lines shown in
In other words, when a coil temperature varies, an increasing slope of the current varies. Therefore, the increasing slope of the electromagnetic attractive force varies, and the Ti-q property line varies. When an injection state is controlled to achieve a request injection start time point and a request injection amount, a robustness of a control of the injection state is deteriorated relative to a variation in the coil temperature.
When a multi-injection in which fuel is divided to be injected for multiple times in a single combustion cycle is executed, it is required that a small amount of fuel is accurately injected. In this case, since an affect of a time lag of the injection start time point with respect to a differential amount of the injection amount is increased, an accuracy of the injection amount becomes remarkably worse due to the variation in the coil temperature.
The present disclosure is made in view of the above matters, and it is an object of the present disclosure to provide a fuel injection controller and a fuel injection system. In the fuel injection controller and the fuel injection system, a robustness of a control of an injection state is improved relative to a variation in the coil temperature.
According to an aspect of the present disclosure, a fuel injection controller is applied to a fuel injector injecting fuel used in a combustion of an internal combustion engine by a valve-opening operation of a valve body according to an electromagnetic attractive force generated by an energization of a coil. The fuel injection controller controls an injection state of the fuel injector by controlling a coil current flowing through the coil.
The fuel injection controller includes a boost circuit which boosts a battery voltage to a boost voltage, an increase control portion which controls the boost voltage to be applied to the coil so as to increase the coil current to be equal to or greater than a first target value, and a constant current control portion which controls a voltage to be applied to the coil so as to reduce the coil current that is increased by the increase control portion and to hold the coil current to be applied to the coil at a second target value.
A property line represents a relationship between an energization time period of the coil and an injection amount. The valve body has a seating surface. The fuel injector has an injection port. The property line has a seat throttle area in which a flow-throttling degree at the seating surface is greater than the flow-throttling degree at the injection port, an injection-port throttle area in which the flow-throttling degree at the injection port is greater than the flow-throttling degree at the seating surface, and a threshold corresponds to an energization time period that is necessary to reach a boundary point between the seat throttle area and the injection-port throttle area from an energization start time point. An initial-current applied time period corresponds to a time period from the energization start time point that the boost voltage starts to be applied to the coil to a time point that the coil current is decreased to the second target value. The increase control portion executes an increase control to control the coil current such that the initial-current applied time period is less than the threshold.
The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:
Embodiments of the present disclosure will be described hereafter referring to drawings. In the embodiments, a part that corresponds to a matter described in a preceding embodiment may be assigned with the same reference numeral, and redundant explanation for the part may be omitted. When only a part of a configuration is described in an embodiment, another preceding embodiment may be applied to the other parts of the configuration. The parts may be combined even if it is not explicitly described that the parts can be combined. The embodiments may be partially combined even if it is not explicitly described that the embodiments can be combined, provided there is no harm in the combination.
Hereafter, a fuel injection controller and a fuel injection system using the fuel injection controller according to an embodiment of the present disclosure will be described referring to drawings. The substantially same parts or components as those in the embodiments are indicated with the same reference numerals and the same descriptions may be omitted. Further, it is to be understood that the disclosure is not limited to the embodiments and constructions. The present disclosure is intended to cover various modification and equivalent arrangements. In addition, while the various combinations and configurations, which are preferred, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the present disclosure.
As shown in
As shown in
When the valve body 12 is closed to make a seating surface 12a arranged at the valve body 12 abut on the seated surface 17b, a fuel injection from the injection port 17a is stopped. When the valve body 12 is opened (lifted up) to make the seating surface 12a separate from the seated surface 17b, the fuel is injected from the injection port 17a. The first coil 13 is configured by winding a bobbin 13a made of resin. The first coil 13 is sealed by the bobbin 13a and a resin member 13b. Thus, a coil body which is cylinder-shaped is constructed by the first coil 13, the bobbin 13a and the resin member 13b.
The stator core 14 is cylinder-shaped using a magnetic metal material. The stator core 14 has a fuel passage 14a. The stator core 14 is disposed on an inner peripheral surface of the body 11, and the bobbin 13a is disposed on an outer peripheral surface of the body 11. The housing 16 covers an outer peripheral surface of the resin member 13b. The housing 16 is cylinder-shaped using a magnetic metal material. A cover member 18 made of a magnetic metal material is placed at an opening end portion of the housing 16. Thus, the coil body is surrounded by the body 11, the housing 16 and the cover member 18.
The movable core 15 is disc-shaped using a magnetic metal material, and is disposed on the inner peripheral surface of the body 11. The body 11, the valve body 12, the coil body, the stator core 14, the movable core 15, and the housing 16 are arranged so that each axis of them is placed concentrically. The movable core 15 is placed at a position between the injection port 17a and the stator core 14. When the first coil 13 is deenergized, a predetermined gap between the movable core 15 and the stator core 14 is generated.
When the first coil 13 is energized to generate an electromagnetic attractive force at the stator core 14, the movable core 15 is moved towards the stator core 14 by the electromagnetic attractive force. The electromagnetic attractive force corresponds to an electromagnetic force. Therefore, the valve body 12 connected with the movable core 15 cancels an elastic force of a main spring SP1 and a fuel-pressure valve-closing force and is lifted up (valve-opening operation). When the first coil 13 is deenergized, the valve body 12 is moved together with the movable core 15 by the elastic force of the main spring SP1 (valve-closing operation).
A portion of the housing 16 which accommodates the first coil 13 is referred to as a coil portion 16a. A portion of the housing 16 which generates the magnetic circuit is referred to as a magnetic circuit portion 16b. In other words, a position of a first end surface of the cover member 18 farther from the injection port 17a than a second end surface of the cover member 18 in an inserting direction is an edge of the magnetic circuit portion 16b. As show in
As shown in
3, a clearance CL is formed between the outer peripheral surface of the housing 16 and the first inner peripheral surface of the attachment hole 4. That is, the outer peripheral surface of the magnetic circuit portion 16b and the first inner peripheral surface 4a of the attachment hole 4 are opposite to each other with the clearance CL. As shown in
The main spring SP1 is arranged at the end part of the valve body 12 opposite to the injection port 17a. A sub spring SP2 is arranged at an end part of the movable core 15 close to the injection port 17a. The main spring SP1 and the sub spring SP2 are coil-shaped and are elastically deformable in the direction along the axis line C. The elastic force of the main spring SP1 corresponding to a main elastic force Fs1 is applied to the valve body 12 in a valve-closing direction as a reactive force of an adjusting pipe 101. An elastic force of the sub spring SP2 corresponding to a sub elastic force Fs2 is applied to the movable core 15 in a pressing direction as a reactive force of a concave portion 11b of the body 11. The pressing direction is a direction where the movable core 15 is pressed towards the locking portion 12d. The main spring SP1 and the sub spring SP2 are elastically deformable according to a movement of the valve body 12 to apply an elastic force to the valve body 12 in the valve-closing direction.
The valve body 12 is provided between the main spring SP1 and the seated surface 17b. The movable core 15 is provided between the sub spring SP2 and the locking portion 12d. The sub elastic force Fs2 of the sub spring SP2 is transmitted to the locking portion 12d via the movable core 15 and is applied to the valve body 12 in a valve-opening direction. Therefore, a computed elastic force Fs that is subtracting the sub elastic force Fs2 from the main elastic force Fs1 is applied to the valve body 12 in the valve-closing direction.
As shown in
The microcomputer 21 includes a central processing unit, a nonvolatile memory (ROM), and a volatile memory (RAM). The microcomputer 21 computes a target injection amount and a target injection-start time, based on a load of the internal combustion engine and a rotational speed of the internal combustion engine. Further, an injection property representing a relationship between an energization time period Ti and an injection amount q is predefined by test. Therefore, the microcomputer 21 controls the energization time period Ti according to the injection property to control the injection amount q. The energization time period Ti is a time period where the first coil is energized. As shown in
The IC 22 includes an injection driving circuit 22a and a charging circuit 22b. The injection driving circuit 22a controls the switching elements SW2, SW3, and SW4. The charging circuit 22b controls the boost circuit 23. The injection driving circuit 22a and the charging circuit 22b are operated according to an injection command signal outputted from the microcomputer 21. The injection command signal, which is a signal for controlling an energizing state of the first coil 13, is set by the microcomputer 21 based on the target injection amount, the target injection start time point, and a coil current value I. The injection command signal includes an injection signal, a boost signal, and a battery signal.
The boost circuit 23 includes a second coil 23a, a condenser 23b, a first diode 23c, and a first switching element SW1. When the charging circuit 22b repeatedly turns on or turns off the first switching element SW1, a battery voltage applied from a battery terminal Batt is boosted by the second coil 23a, and is accumulated in the condenser 23b. In this case, the battery voltage after being boosted and accumulated corresponds to a boost voltage.
When the injection driving circuit 22a turns on both a second switching element SW2 and a fourth switching element SW4, the boost voltage is applied to the first coil 13. When the injection driving circuit 22a turns on both a third switching element SW3 and the fourth switching element SW4, the battery voltage is applied to the first coil 13. When the injection driving circuit 22a turns off the switching elements SW2, SW3 and SW4, no voltage is applied to the first coil 13. When the second switching element SW2 is turned on, a second diode 24 shown in
A shunt resistor 25 is provided to detect a current flowing through the fourth switching element SW4, that is, the shunt resistor 25 is provided to detect a current (coil current) flowing through the first coil 13. The microcomputer 21 computes the coil current value I based on a voltage decreasing amount according to the shunt resistor 25.
Hereafter, an electromagnetic attractive force (valve-opening force) generated by the coil current will be described.
The electromagnetic attractive force increases in accordance with an increase in magnetomotive force (ampere turn AT) generated in the stator core 14. Specifically, in a condition where a number of turns of the first coil 13 is fixed, the electromagnetic attractive force increases in accordance with an increase in ampere turn AT. An increasing time period is necessary for the electromagnetic attractive force to be saturated and become the maximum value since the first coil 13 is energized. According to the embodiment, the maximum value of the electromagnetic attractive force is referred to as a static attractive force Fb.
In addition, the electromagnetic attractive force required for starting to open the valve body 12 is referred to as a required valve-opening force Fa. The required valve-opening force increases in accordance with an increase in pressure of the fuel supplied to the fuel injector 10. Further, the required valve-opening force may be increased according to various conditions such as an increase in viscosity of fuel. The maximum value of the required valve-opening force is referred to as the required valve-opening force Fa.
At the time point t10, the boost voltage is applied to the first coil 13 so that the first coil 13 starts to be energized. As shown in
Next, the first coil 13 is controlled by the battery voltage to hold the coil current at a second target value I2 that is less than the first target value I1. Specifically, a duty control is executed so that a difference between the coil current value I and the second target value I2 is in a predetermined range. In the duty control, an on-off energization of the battery voltage is repeated since a time point t30 to hold an average value of the coil current at the second target value I2. In this case, the microcomputer 21 controlling as above corresponds to a constant current control portion 21b. The second target value I2 is set to a value so that the static attractive force Fb is greater than or equal to the required valve-opening force Fa.
Next, the first coil 13 is controlled by the battery voltage to hold the coil current at a third target value I3 that is less than the second target value I2. Specifically, a duty control is executed so that a difference between the coil current value I and the third target value I3 is in a predetermined range. In the duty control, an on-off energization of the battery voltage is repeated since a time point t50 to hold an average value of the coil current at the third target value I3. In this case, the microcomputer 21 controlling as above corresponds to a hold control portion 21c.
As shown in
The electromagnetic attractive force is held to a predetermined force during a hold control time period from the time point t50 to the time point t60. The third target value I3 is set so that a valve-opening hold force Fc is less than the predetermined force. The valve-opening hold force Fc is necessary to hold the valve body 12 to be open. The valve-opening hold force Fc is less than the required valve-opening force Fa.
The injection signal of the injection command signal is a pulse signal dictating to the energization time period Ti. A pulse-on time point of the injection signal is set to the time point t10 by an injection delay time earlier than a target energization start time point. A pulse-off time point of the injection signal is set to the energization stop time point t60 after the energization time period Ti has elapsed since the time point t10. The fourth switching element SW4 is controlled by the injection signal.
The boost signal of the injection command signal is a pulse signal dictating to an energization state of the boost voltage. The boost signal has a pulse-on time point as the same as the pulse-on time point of the injection signal. Next, the boost signal is repeatedly turned on or off until the coil current value I reaches the first target value I1. The second switching member SW2 is controlled by the boost signal. The boost voltage is applied to the first coil 13 during the increase control time period.
The battery signal of the injection command signal is turned on at the time point t30. In this case, the time point t30 corresponds to a constant-current control start time point t30. Next, the battery signal is repeatedly turned on or off to execute a feedback control during a time period that a predetermined time has elapsed since the energization start time point t10. In this case, the feedback control holds the coil current value I at the second target value I2. Next, the battery signal is repeatedly turned on or off to execute a feedback control until the injection signal is turned off. In this case, the feedback control holds the coil current value I at the third target value I3. The third switching element SW3 is controlled by the battery signal.
As shown in
As shown in
As shown in
In the fuel injector 10 according to the present embodiment, a slope of the Ti-q property line in the seat throttle area B1 is greater than the slope of the Ti-q property line in the injection-port throttle area B2. In other words, in the seat throttle area B1, the slop of the Ti-q property line varies gradually.
A pressure (fuel pressure) Pc of the fuel supplied to the fuel injector 10 is detected by a pressure sensor 30 shown in
As shown in
As the above description, the fuel injection controller has the following features. Further, effects of the features will be described.
(a) The increase control portion 21a controls the coil current such that an initial-current applied time period Ta is less than or equal to a threshold Tth that is predetermined. The threshold Tth corresponds to the energization time period Ti that is necessary to reach a boundary point between the seat throttle area B1 and the injection-port throttle area B2 from the time point t10. According to the present embodiment, the boundary point corresponds to the time point t2. According to the present embodiment, the initial-current applied time period Ta is less than the threshold Tth. As shown in
When the valve body is sufficiently lifted up, a flow-throttling degree at the injection port is greater than the flow-throttling degree at the seating surface. The flow-throttling degree at the injection port corresponds to a fuel-pressure loss generated at the injection port, and the flow-throttling degree at the seating surface corresponds to the fuel-pressure loss generated at the seating surface. Further, the fuel-pressure loss generated at the injection port is referred to as an injection-port pressure loss, and the fuel-pressure loss generated at the seating surface is referred to as a seat pressure loss. The injection amount is determined by the injection-port pressure loss. When the lift amount is small right after the valve body starts to open, the flow-throttling degree at the seating surface is greater than the flow-throttling degree at the injection port. The injection amount is determined by the seat pressure loss. The seat throttle ratio is a ratio of the seat pressure loss relative to a sum of the seat pressure loss and the injection-port pressure loss.
Even when the boost voltage is different, the Ti-q property differential amount sharply decreases since the time point that the seat throttle ratio is 50%.
Ta is less than the threshold Tth and the first coil 13 is deenergized before the valve body 12 starts to open. Further, the lines L1c and L1d are test results that the coil temperature is the high temperature, and the lines L2c and L2d are test results that the coil temperature is the normal temperature. As shown in
Hereafter, test results shown in
According to the present embodiment, a material of the first coil 13 is selected such that a resistance of the first coil 13 is small to meet a condition that the initial-current applied time period Ta is short and is less than the threshold Tth.
(b) As shown in
However, when the initial-current applied time period Ta is shortened to be less than the threshold Tth, an increasing rate of the coil current according to the increase control is necessary to be increased. Therefore, a heat generation of the ECU 20 becomes larger, and parts of the ECU 20 may be damaged due to the heat generation.
According to the present embodiment, the coil current is prohibited from flowing in the opposite direction during the decreasing time period. Therefore, the heat generation of the ECU 20 can be restricted, and a damage to parts of the ECU 20 can be reduced.
(c) When the valve body 12 is lifted up to the maximum valve-opening position, the movable core 15 collides with the stator core 14. Therefore, a bounce of the movable core 15 may occur relative to the stator core 14. Specifically, the movable core 15 instantly moves in the valve-closing direction according to a reaction of a collision between the movable core 15 and the stator core 14, and the movable core 15 collides with the stator core 14 again. Then, a stroke variation amount is generated by the bounce of the movable core 15. As shown in
(d) As the above description, the body 11, the housing 16, the cover member 18, the stator core 14, and the movable core 15 generate the magnetic circuit. An adjacent member adjacent to the coil body includes the body 11, the housing 16, and the cover member 18. A non-adjacent member that is not adjacent to the coil body includes the stator core 14 and the movable core 15. An electrical resistivity of the adjacent member is greater than that of the non-adjacent member. The electrical resistivity corresponds to a specific electrical resistance p. For example, the adjacent member may be made of a sintered material, and the non-adjacent member may be made of an ingot material. The sintered material is formed by pressing metal powders, and the ingot material is formed by melting a metal.
Since the electrical resistivity of the adjacent member is increased, an eddy current generated in the magnetic circuit according to the energization of the first coil 13 can be canceled. Therefore, the increasing rate of the coil current can be increased while the coil current is increased by the increase control portion 21a, and the decreasing rate of the coil current can be increased from the first target value to the second target value. In other words, the condition that the initial-current applied time period Ta is shortened to be less than the threshold Tth can be readily achieved.
(e) According to the present embodiment, an outer peripheral surface of at least a part of the coil portion 16a is surrounded by the first inner peripheral surface 4a over the whole periphery. Since a temperature of the cylinder head 3 becomes a high temperature, the coil temperature readily becomes the high temperature in a case where the coil portion 16a is surrounded by the attachment hole 4. The variation in the coil temperature becomes large, and the temperature property variation may occur.
According to the present embodiment, since the coil portion 16a is surrounded by the cylinder head 3 having the high temperature, the robustness of the control of the injection state is improved relative to the variation in the coil temperature.
Further, a cylinder block may be used instead of the cylinder head 3 to surround the coil portion 16a.
(f) The increase control portion 21a controls the coil current to meet the condition that the initial-current applied time period Ta is less than the threshold Tth, in a case where a multi-injection in which fuel is divided to be injected for multiple times in a single combustion cycle is executed, or a case where the internal combustion engine is operating in an idle operation. The increasing slope of the injection amount q in the seat throttle area B1 is sharper than that in the injection-port throttle area B2. Therefore, the temperature property variation is readily generated. Since the injection amount is small when the multi-injection is executed or the internal combustion engine is operating in the idle operation, it is a high probability that the internal combustion engine operates in the seat throttle area B1. Therefore, the robustness of the control of the injection state is improved relative to the variation in the coil temperature.
Further, when the internal combustion engine is operating other than the multi-injection and the idle operation, the coil current is decreased from the first target value I1, and the coil current is held to the second target value I2 by the constant current control portion 21b. Therefore, an energy applied to the first coil 13 is reduced, and a circuit load of the ECU 20 can be reduced.
(g) When the initial-current applied time period Ta is shortened to be less than the threshold Tth, the increasing rate of the coil current according to the increase control is necessary to be increased. Therefore, a heat generation generated in the boost circuit 23 becomes large, or the coil temperature becomes high. According to the present embodiment, as shown in
As shown in
A time period that the boost voltage is applied to the first coil 13 to increase the coil current to the first target value I1 in the increase control can be shortened. Therefore, a heat-generation amount of the boost circuit 23 having the ECU 20 can be reduced, and a damage of the ECU 20 due to the heat generation can be reduced.
According to the present embodiment, the pre charge control is permitted in a condition that the pressure of the fuel supplied to the fuel injector 10 is greater than or equal to a predetermined pressure. In this case, the pressure of the fuel supplied to the fuel injector 10 is referred to as a supplied pressure. Specifically, when the fuel pressure
Pc is less than the predetermined pressure, the pre charge control is permitted. Since the fuel pump P is driven by the internal combustion engine, the supplied pressure varies in accordance with the rotational speed of the internal combustion engine. The pre charge control may be permitted in a condition that the rotational speed is greater than or equal to a predetermined speed.
The electromagnetic attractive force necessary to open the fuel injector 10 decreases in accordance with a decrease in supplied pressure. When the supplied pressure is low, the first target value I1 can be sufficiently decreased without executing the pre charge control, and a loss of the energy applied to the first coil 13 can be reduced. When the pre charge control is executed, since an energization time period of one time injection is increased during a time period from the time point t0 to the time point t10, a limit of an interval of the multi-injection cannot be shortened.
According to the present embodiment, since the pre charge control is permitted in the condition that the supplied pressure is greater than or equal to the predetermined pressure, the pre charge control is not executed in a case where the supplied pressure is low. Therefore, the limit of the interval of the multi-injection can be shortened.
The Ti-q property line becomes different according to the supplied pressure. Specifically, since a force necessary to open the valve body 12 decreases in accordance with the decrease in supplied pressure, the energization time period Ti that is necessary to reach the boundary point between the seat throttle area B1 and the injection-port throttle area B2 decreases in accordance with the decrease in supplied pressure. In other words, the threshold Tth decreases in accordance with the decrease in supplied pressure.
According to a third embodiment, since the threshold Tth decreases in accordance with the decrease in supplied pressure, the first target value I1 is set lower when the supplied pressure is lower. Therefore, the initial-current applied time period Ta is shortened. Further, a reliability for executing the increase control according to the supplied pressure to meet the condition that the initial-current applied time period Ta is less than the threshold Tth.
The initial-current applied time period Ta can be shortened by increasing an increasing slope of the coil current in the increase control, a circuit in which the increasing slope is changeable is necessary. A circuit configuration becomes complicated. According to the present embodiment, since the initial-current applied time period Ta can be shortened by only setting the first target value I1 to be lower, the circuit configuration can be simplified.
The electromagnetic attractive force necessary to open the fuel injector 10 decreases in accordance with the decrease in supplied pressure. Therefore, when the second target value I2 is not decreased, a valve-opening time point becomes faster, and the slope of the Ti-q property line is increased in the seat throttle area B1. Further, a variation of the Ti-q property line generated due to disturbance such as temperature becomes larger, and the accuracy of an injection-amount control is deteriorated in the seat throttle area B1.
According to the present embodiment, since the second target value I2 is set lower when the supplied pressure is lower, it is prevented from increasing the slope of the Ti-q property line in the seat throttle area B1. Therefore, the accuracy of an injection-amount control can be improved in the seat throttle area B1.
According to the present embodiment, the increase control is executed by the increase control portion 21a at a fuel pressure greater than the point TP. For example, the increase control is prohibited in a case where the fuel pressure Pc is less than a pressure of the point TP. As shown in
A limit of the supplied pressure that is able to open the valve body 12 is referred to as an injection limit pressure. The increase control can be executed in a case where the fuel pressure, for example, the pressure PB shown in
According to the present embodiment, since the increase control is executed at the pressure greater than or equal to the point TP, the bounce amount can be remarkably reduced. Further, the pulse generated relative to the Ti-q property line can be reduced, and the accuracy of the injection-amount control can be improved.
E2 with dots are integrated values of the coil currents applied to the first coil 13 to increase the coil current to the first target value I1. The integrated values E1, E2 are referred to as initial energy applied amounts E1, E2. The initial energy applied amount varies according to the coil temperature. The increase control portion 21a controls the coil current such that differential amounts of the initial energy applied amounts E1, E2 generated due to the variation in the coil temperature are less than a predetermined value. For example, the predetermined value is set to 10%.
Specifically, the increase control is executed such that a condition that the differential amount of the initial energy applied amount is less than 10% is met, even though the waveform of the coil current varies in a coil-temperature width. In this case, the coil-temperature width corresponds to an operating condition of the fuel injector 10, such as from −30 degrees centigrade to 160 degrees centigrade. In addition, when the internal combustion engine is started such that the first coil 13 is energized for the first time to inject fuel for the first time, the increase control is not limited to the above condition. Alternatively, when the internal combustion engine is started such that the fuel injection amount is increased, the increase control is not limited to the above condition.
According to the first embodiment, the boost voltage applied to the first coil 13 is terminated at the time point that the coil current reaches the first target value I1. Therefore, as shown in
According to the present embodiment, since the resistance of the first coil 13 increases in accordance with an increase in coil temperature, the coil current is controlled such that the peak value Ipeak decreases in accordance with an increase in resistance of the first coil 13. Specifically, the first switching element SW1 uses a field effective transistor (FET) having a discharge capacity greater than or equal to a predetermined capacity. For example, the first switching element SW1 may use a metal-oxide-semiconductor field-effect transistor (MOSFET).
An overshoot amount increases in accordance with an increase in increasing rate of the coil current. Therefore, the peak value Ipeak increases. When the resistance of the first coil 13 becomes greater according to the coil temperature, the peak value Ipeak becomes smaller. When the discharge capacity of the MOSFET is sufficiently large, a variation of the peak value Ipeak is excessively small and can be omitted. In this case, it can be determined that the peak value Ipeak is not changed. According to the present embodiment, since the MOSFET having a sufficiently large discharge capacity is used, the peak value Ipeak decreases in accordance with an increase in coil temperature.
When the increasing rate of the coil current is decreased due to the high temperature, a time period for the coil current to reach the first target value I1 becomes longer. Further, when the peak value Ipeak is high, the initial energy applied amount is increased. According to the present embodiment, since the MOSFET having a sufficiently large discharge capacity is used, the peak value Ipeak decreases in accordance with an increase in coil temperature. As the above description according to the present embodiment, the initial energy applied differential amount can be readily decreased. In other words, the MOSFET is used such that the initial energy applied differential amount is less than the predetermined value.
According to the first embodiment, the coil current is controlled such that the initial-current applied time period Ta is less than the threshold Tth, and the threshold Tth corresponds to the energization time period Ti that is necessary to reach the boundary point between the seat throttle area B1 and the injection-port throttle area B2 from the time point t10. In other words, the boost voltage applied to the first coil 13 is terminated at the time point that the seat throttle ratio reaches 50%. According to the present embodiment, in
When the seating surface 12a separates from the seated surface 17b right after the time point t1, since a flow-throttling degree of the seating surface 12a is large, a fuel-pressure valve-opening force corresponding to the fuel pressure applied to the seating surface 12a and other parts downstream of the valve body 12 is small. Therefore, a lift-up rate of the valve body 12 is slow, and the slope of the Ti-q property line is small. However, even in the partial area A1, since the flow-throttling degree decreases in accordance with an increase in lift amount, the fuel-pressure valve-opening force becomes greater. Therefore, the lift-up rate becomes faster, and the slope of the Ti-q property line becomes greater.
In a first period of the partial area A1, the slope of the Ti-q property line is small because a seat-throttling degree is large. In a second period of the partial area A1, the slope of the Ti-q property line becomes greater because the seat-throttling degree becomes smaller. Thus, the slope of the Ti-q property line increases in accordance with the increase in lift amount.
In addition, the slope of the Ti-q property line exponentially increases in accordance with the increase in lift amount. Further, the turning point P1 is a point that an increasing rate of the slope is the maximum. Specifically, at the turning point P1, a second derivative value of the Ti-q property line is the maximum, and the increasing rate of the slope is the maximum. Therefore, the injection amount q increases sharply from the turning point P1.
When the coil current is sharply increased to increase the electromagnetic attractive force while the gap between the stator core 14 and the movable core 15 is large, the variation of the electromagnetic attractive force due to the coil temperature becomes smaller. Therefore, the temperature property variation decreases in accordance with a decrease in initial-current applied time period Ta.
According to the present embodiment, the increase control portion 21a controls the coil current such that a boost energization stop time point t20 that the boost voltage applied to the first coil 13 is terminated is ahead of the time point td that the injection amount q reaches the turning point P1. In other words, the boost voltage is terminated before the injection amount q reaches the turning point P1. When the coil current is sharply increased to increase the electromagnetic attractive force while the gap between the stator core 14 and the movable core 15 is large, the variation of the electromagnetic attractive force due to the coil temperature may become smaller. Therefore, the temperature property variation can be decreased in accordance with a decrease in initial-current applied time period Ta.
According to the first embodiment, the energization time period Ti that is necessary to reach the boundary point between the seat throttle area B1 and the injection-port throttle area B2 from the time point t10 is set as the threshold Tth, and the coil current is controlled such that the initial-current applied time period Ta is less than the threshold
Tth. According to the present embodiment, as shown in
When the initial-current applied time period Ta is less than the threshold Tth, the temperature property variation can be restricted. Further, the threshold Ttha set according to the lift amount is substantially equal to the threshold Tth set according to the boundary point between the seat throttle area B1 and the injection-port throttle area B2. Thus, the present embodiment can achieve the same effects as the first embodiment. That is, when the coil current is sharply increased to increase the electromagnetic attractive force while the gap between the stator core 14 and the movable core 15 is large, the variation of the electromagnetic attractive force due to the coil temperature becomes smaller.
The present disclosure is not limited to the above embodiments, and may change as followings. Further, various combinations of the features of the above embodiments are also within the spirit and scope of the present disclosure.
(a) According to the present disclosure, it is not limited to the fuel injector having the Ti-q property line as shown in
(b) According to the first embodiment, in
(c) As shown in
(d) As shown in
(c) As shown in
(d) According to the first embodiment, when the coil current is increased to the first target value I1 by the increase control, the coil current is decreased to the second target value I2. However, the coil current may be held to the first target value I1 after the coil current is increased to the first target value I1 by the increase control, and then may be decreased to the third target value I3. In other words, the second target value I2 may be set to a value equal to the first target value I1 in the first embodiment.
(e) According to the above embodiments, the entire of the magnetic circuit portion 16b is surrounded over the whole periphery by the first inner peripheral surface 4a of the attachment hole 4. However, according to the present disclosure, a part of the magnetic circuit portion 16b may be surrounded over the whole periphery by the first inner peripheral surface 4a of the attachment hole 4. Alternatively, the entire of the coil portion 16a may be surrounded over the whole periphery by the first inner peripheral surface 4a of the attachment hole 4 in the inserting direction. Alternatively, a part of the coil portion 16a may be surrounded over the whole periphery by the first inner peripheral surface 4a of the attachment hole 4 in the inserting direction.
(f) As shown in
(g) According to the first embodiment, the adjacent member uses a sintered material made of a metal such that the electrical resistivity of the adjacent member is greater than that of the non-adjacent member. However, at least a part of the adjacent member or at least a part of the non-adjacent member may be mixed with the sintered material.
(h) According to the third embodiment, the first target value I1 and the second target value I2 are changed according to the supplied pressure. However, the first target value I1 or the second target value I2 may be previously determined without respect to the supplied pressure.
(i) According to the above embodiments, when the coil current reaches the first target value I1, the first coil 13 is deenergized, and the coil current is decreased. However, the coil current may be held to the first target value I1 for a predetermined time period after the coil current reaches the first target value I1, and then the coil current is decreased.
(j) According to the above embodiments, the constant current control is executed by using the battery voltage. However, the constant current control may be executed by using the boost voltage.
(k) According to the fifth embodiment, the increase control is executed such that the initial energy applied differential amounts E1, E2 are less than the predetermined value that is 10%. However, the predetermined value may be set to 5%, 2%, or 1%.
(l) According to the second embodiment, the third embodiment, the fourth embodiment, the fifth embodiment, and the sixth embodiment, the condition that the initial-current applied time period Ta is less than the threshold Tth is used. However, these embodiments may use a condition that the time point t20 is ahead of the time point td, or a condition that the initial-current applied time period Ta is less than the threshold Ttha.
While the present disclosure has been described with reference to the embodiments thereof, it is to be understood that the disclosure is not limited to the embodiments and constructions. The present disclosure is intended to cover various modification and equivalent arrangements. In addition, while the various combinations and configurations, which are preferred, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the present disclosure.
Number | Date | Country | Kind |
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2013-34932 | Feb 2013 | JP | national |
This is a continuation of U.S. application Ser. No. 15/270,013, filed Sep. 20, 2016 which is a continuation of U.S. application Ser. No. 14/189,351, filed Feb. 25, 2014 which claims priority to Japanese Patent Application No. 2013-034932 filed on Feb. 25, 2013, the disclosures of each of which are incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
Parent | 15270013 | Sep 2016 | US |
Child | 15966058 | US | |
Parent | 14189351 | Feb 2014 | US |
Child | 15270013 | US |