Patent Application
20230038318
The present invention relates to a control device for a high-pressure fuel pump.
An internal combustion engine of an automobile is required to have high efficiency, low exhaust, and high output. As means for solving these requirements in a well-balanced manner, direct injection internal combustion engines have been widely used for a long time. Automobile manufacturers and suppliers have constantly made efforts to improve product values, and one of important problems is to achieve low noise of a high-pressure fuel pump. In order to achieve the low noise of the high-pressure fuel pump, a drive current of the high-pressure fuel pump may be reduced, but when the drive current is excessively reduced, the high-pressure fuel pump cannot discharge fuel. An optimum current application amount for achieving low noise varies depending on the individual of the high-pressure fuel pump. In the low noise control of the pump of the related art, a technique disclosed in the following PTL 1 has been used in order to examine a minimum current application amount for each individual pump within a range in which the discharge of the fuel does not fail.
As an example of the low noise control of the pump of the related art, claim 1 of PTL 1 discloses an invention of “a control device for a high pressure pump comprising motion detection means for detecting a motion of a valve body with respect to a drive command of a control valve when an electromagnetic portion is energized by the drive command to displace the valve body to a target position, and energization control means for performing power reduction control of reducing, by a predetermined amount, a supply power to be supplied to the electromagnetic portion at the time of subsequent energization later than a time of previous energization, when the motion detection unit detects that the valve body is displaced to the target position at the time of the previous energization”.
Claim 2 of PTL 1 discloses an invention that “the control device for a high pressure pump according to claim 1, wherein the energization control means performs power increase control to increase, by a predetermined amount, the supply power to be supplied to the electromagnetic portion at the time of the subsequent energization from the supply power at the time of the previous energization when the motion detection unit does not detect that the valve body is displaced to the target position at the time of the previous energization”.
PTL 1: JP 2017-75609 A
Incidentally, a normally opened high-pressure fuel pump, an anchor collides with a fixing core before a suction valve constituting the high-pressure fuel pump is closed. When an excessive current is energized to the solenoid in order to successfully close the valve in all the high-pressure fuel pumps regardless of individual differences of the high-pressure fuel pumps, since a speed at which the anchor moves toward the fixing core increases, a large noise is generated when the anchor collides with the fixing core. On the other hand, in order to reduce this noise, when a method of the related art in which the control device repeatedly increases or decreases the current application amount near a minimum current application amount that can be closed to search for a minimum value of the current application amount is used, valve closing failure occurs at a constant frequency.
The present invention has been made in view of such a situation, and an object thereof is to perform low noise control of a high-pressure fuel pump without causing valve closing failure.
A control device for a high-pressure fuel pump according to the present invention controls a suction valve that opens and closes an inflow port through which fuel flows into a pressurizing chamber by performing energization to a solenoid in synchronization with a reciprocating motion of a plunger. A current energized to the solenoid includes a peak current for giving a force to start closing a valve to the suction valve in a stationary state and a holding current for performing switching in a range smaller a maximum value of the peak current in order to hold the suction valve in a valve closing state. When control device reduces a peak current application amount of the peak current from a value sufficient to close the high-pressure fuel pump, a valve closing speed of the suction valve becomes small up to a certain application amount, and when the peak current application amount becomes smaller than the application amount, there is a saturation range of a current application amount of the peak current in which the valve closing speed of the suction valve is saturated. The control device controls the current application amount of the peak current to fall in the saturation range.
According to the present invention, it is possible to control the current energized to the solenoid in the region where the noise can be most reduced without using the method of the related art for searching for the most appropriate current application amount for achieving low noise by repeating the valve closing success and the valve closing failure.
Other objects, configurations, and effects will be made apparent in the following descriptions.
Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings, but the present embodiments are not limited to the embodiments described in the drawings. In the present specification and drawings, components having substantially the same function or configuration are denoted by the same reference signs, and thus, the redundant description will be omitted.
A control device according to each embodiment to be described below is applied to control of a normally opened high-pressure fuel pump. In the normally opened high-pressure fuel pump, a valve body (suction valve) is opened when a current does not flow in a solenoid, and the valve body is closed when the current flows in the solenoid. In the normally opened high-pressure fuel pump, the valve body is closed to prevent fuel compressed by the rising of a plunger from returning to a low pressure pipe side, and the fuel is discharged to a high pressure pipe side. However, when the valve closing and the valve opening are replaced, a control device according to a first embodiment can also be applied to control of a normally closed high-pressure fuel pump.
Before describing a control device according to first to third embodiments to which the present invention is applied, examples of configurations and operations of a high-pressure fuel pump and a control device common to the embodiments will be described with reference to
In the direct injection internal combustion engine 10, fuel stored in a fuel tank 101 is pressurized to about 0.4 MPa by a feed pump 102, and flows into a high-pressure fuel pump 103 via a low pressure pipe 111. The fuel is further pressurized to several tens of MPa by the high-pressure fuel pump 103. The pressurized fuel is injected from a direct injection injector 105 to a cylinder 106 of the direct injection internal combustion engine 10 via a high pressure pipe 104.
The injected fuel is mixed with air sucked into the cylinder 106 by an operation of a piston 107. The air-fuel mixture is ignited by a spark generated by an ignition plug 108 and explodes. The air-fuel mixture in the cylinder 106 expands by heat generated by the explosion, and pushes down the piston 107. A force pushing down the piston 107 rotates a crankshaft 110 via a link mechanism 109. The rotation of the crankshaft 110 is transmitted to wheels through a transmission and becomes a force for moving a vehicle.
Generally, an internal combustion engine is mainly required to have low fuel consumption, high output, and exhaust gas purification, but noise and vibration are required to be reduced as further added values. In the high-pressure fuel pump 103, when a suction valve that sucks fuel is opened and closed, a valve body or an anchor collides with a stopper, and thus, noise is generated. Automobile manufacturers and suppliers make a lot of efforts to reduce noise. Hereinafter, a structure example of the high-pressure fuel pump 103 to be controlled by the control device according to the present embodiment will be described.
The high-pressure fuel pump 103 illustrated in
A plunger 202 included in the high-pressure fuel pump 103 moves up and down by rotation of a cam 201 attached to a camshaft of the direct injection internal combustion engine 10. An anchor 204 is attracted to a fixing portion 206 in synchronization with a vertical movement of the plunger 202, and thus, a suction valve 203 opens and closes an inflow port 225. A solenoid 205 that generates an electromagnetic force by energizing a current I controls an opening and closing operation of the suction valve 203. The anchor 204 is attracted to a fixing core (fixing portion 206) by the electromagnetic force generated by the solenoid 205, and controls the operation of the suction valve 203.
The high-pressure fuel pump 103 is surrounded by a casing 223, and a pressurizing chamber 211 is disposed therein. The pressurizing chamber 211 is a region in a range divided by a communication port 221 and an outflow port 222. From the low pressure pipe 111 side, the fuel flows into the pressurizing chamber 211 through the inflow port 225 and the communication port 221. The fuel flowing into the pressurizing chamber 211 is discharged to the high pressure pipe 104 side through the outflow port 222.
The outflow port 222 is opened and closed by a discharge valve 210. The discharge valve 210 is constantly biased by a spring portion 226 in a direction of closing the outflow port 222, and when a pressure of the pressurizing chamber 211 exceeds a spring force of the spring portion 226, the outflow port 222 is opened, and the fuel is injected.
In the high-pressure fuel pump 103, an operation of the anchor 204 in an axial direction (left-right direction in
When the energization of the solenoid 205 is turned on, a magnetic attraction force Fmag is generated between the fixing portion 206 (magnetic core) and the anchor 204. Due to the magnetic attraction force Fmag, the anchor 204 provided on a proximal end (root portion of the first spring 209) side of the suction valve 203 is attracted in a valve closing direction (left direction in
In a state where the anchor 204 is attracted to the fixing portion 206, the suction valve 203 is a check valve that is opened and closed based on a differential pressure between an upstream side and a downstream side and a biasing force of a second spring 215. Thus, as a pressure on the downstream side of the suction valve 203 increases, the suction valve 203 moves in the valve closing direction. When the suction valve 203 moves by a lift amount set in the valve closing direction, since a projection of the suction valve 203 is seated on a seat portion 207 and the suction valve 203 is closed, the fuel in the pressurizing chamber 211 cannot flow back to the low pressure pipe 111 side. Accordingly, the fuel compressed by the rising of the plunger 202 is discharged to the high pressure pipe through the outflow port 222.
Operations (mainly, the energization to the solenoid 205 and the movement of the anchor 204) of the high-pressure fuel pump 103 are controlled by an electromagnetic actuator control device 113. The electromagnetic actuator control device 113 is an example of the control device according to the present invention. The operations of the electromagnetic actuator control device 113 are controlled by a drive pulse output from an internal combustion engine control device (hereinafter, an engine control unit (ECU)) 114 that controls the entire operation of the direct injection internal combustion engine 10. Operation information from the electromagnetic actuator control device 113 and operation information of the high-pressure fuel pump 103 (rotation angle of the camshaft detected by a camshaft sensor, and the like) are input to the ECU 114.
The electromagnetic actuator control device 113 includes a current measurement circuit 301 that measures the current I energized to the solenoid 205 and converts the current I into a voltage, a differentiation circuit 302 that differentiates the voltage converted by the current measurement circuit 301, an absolute value circuit 303 that obtains an absolute value of the differentiated voltage, a smoothing circuit 304 that smooths an output of the absolute value circuit 303, a storage element 305 that stores a value (for example, a maximum value of a peak current Ia) used for controlling the high-pressure fuel pump 103, and a power supply control circuit 306 that controls an operation of the power supply 112 that controls the solenoid 205. A detailed operation of each unit of the electromagnetic actuator control device 113 will be described later with reference to
As illustrated in an uppermost stage of
The power supply control circuit 306 of the electromagnetic actuator control device 113 controls the power supply 112 such that the power supply 112 starts to apply a voltage V indicated by a voltage waveform of
The current I energized to the solenoid 205 is increased by the voltage V according to the following Equation (1).
In Equation (1), L indicates an inductance of the solenoid 205, and R indicates a resistance of a wiring. As the current I increases, the magnetic attraction force Fmag by which the fixing portion 206 attracts the anchor 204 also increases.
When the magnetic attraction force Fmag becomes larger than the spring force Fsp of the first spring 209, the anchor 204 pressed by the spring force Fsp starts to move toward the fixing portion 206 (timing t2). When the anchor 204 moves, the suction valve 203 is also moved toward the fixing portion 206 following the anchor 204 by being pressed by the fuel pressurized by the rising of the plunger 202.
As illustrated in the graph of the current I in
After timing t3, the holding current Ib is energized to the solenoid 205. The holding current Ib indicated by a horizontal line portion in the current waveform in the drawing indicates a current energized to the solenoid 205 by switching the voltage in order to attract the anchor 204 approaching the fixing portion 206 until colliding with the fixing portion 206 and maintain the contact state after the collision. By switching the voltage, this current oscillates in a certain range. Here, a maximum current value of the peak current Ia is “Im”, and a maximum current value of the holding current Ib is “Ik”.
Eventually, the protrusion provided at the distal end of the suction valve 203 collides with the seat portion 207, and the suction valve 203 is seated. A flow path of the fuel indicated by the dashed dotted line 212 in
When the pressure of the pressurizing chamber 211 becomes larger than a spring force Fsp_out (see
As illustrated in a fifth stage from the top in
The anchor 204 moves from the valve closing position to the valve opening position together with the suction valve 203 due to the decrease in the fuel pressure of the pressurizing chamber 211 (timings t7 to t8).
By such an operation, the high-pressure fuel pump 103 sends the fuel from the low pressure pipe 111 to the high pressure pipe 104. In this process, noise is generated when the anchor 204 collides with the fixing portion 206 after the valve closing is completed (timing t4) and when the suction valve 203 and the anchor 204 collide with the stopper 208 and the valve opening is completed (timing t8). In particular, noise generated when the anchor 204 collides with the fixing portion 206 is large. This noise may make drivers feel uncomfortable particularly when idling, and automobile manufacturers and suppliers of high-pressure fuel pumps are overcoming this noise reduction. Thus, the electromagnetic actuator control device 113 according to the present embodiment has been invented particularly for the purpose of reducing noise generated when the valve closing is completed.
Here, the current energized to the solenoid 205 in order for the electromagnetic actuator control device 113 to drive the high-pressure fuel pump 103 will be described.
As described above, the current for driving the high-pressure fuel pump 103 roughly includes the peak current Ia and the holding current Ib. When the peak current Ia is integrated in a period from timings t1 to t3 illustrated in
Since the peak current Ia is energized to the solenoid 205 in order to give the closing force to the suction valve 203 and the anchor 204, when the peak current integral value II is reduced, a force to close the valve is weakened, and noise can be reduced. However, when the peak current integral value II is excessively reduced, the valve closing fails. Thus, there has been a demand for reducing the peak current integral value II as much as possible within a range in which the suction valve 203 is closed.
Incidentally, there is a problem that the peak current integral value II at a limit at which the suction valve 203 is closed depends on individual characteristics of the high-pressure fuel pump 103. Here, a change in a minimum peak current integral value II depending on an individual difference (spring force Fsp) of the first spring 209 that is dominant among individual differences in order to close the valve will be described with reference to
In the present embodiment, the peak current integral value II used as a current application amount is calculated as an integral value integrated in a predetermined period from the start of energization of the peak current Ia. However, the current application amount may be defined by any one of an integral value of the square of the peak current Ia integrated in the predetermined period from the start of energization of the peak current Ia or an integral value of a product of the current I energized to the solenoid 205 and the voltage V applied to the solenoid 205.
It can be seen from
Thus, a method for controlling the valve closing of the suction valve 203 near a valve closing limit by repeating control for gradually reducing the peak current integral value II when the valve closing succeeds and increasing the peak current integral value II when the valve closing fails is considered. However, in this method, valve closing failure occurs at a certain frequency.
In order to avoid such valve closing failure, the present inventors have examined the characteristics of the high-pressure fuel pump 103, and have found that there is a dead zone 500 illustrated in
Thus, the current application amount and the force of closing the valve have a relationship in which the current application amount is reduced and the valve closing speed becomes slow when the current application amount is larger than a value sufficient to close the suction valve 203 and the valve closing speed is constant when the current application amount is equal to or less than a predetermined value.
As described above, when the peak current integral value II is larger than the current application amount limit value 501, the valve-closing-completion-immediately-preceding speed vel_Tb is also reduced along with the reduction of the peak current integral value II. However, in a region smaller than the current application amount limit value 501, the valve-closing-completion-immediately-preceding speed vel_Tb does not decrease and is maintained at a constant value even though the peak current integral value II is reduced. That is, there is the dead zone 500 in the peak current integral value II and the valve-closing-completion-immediately-preceding speed vel_Tb. The dead zone has a lower limit, and when the peak current integral value II is smaller than the lower limit, the valve closing fails due to the insufficient magnetic attraction force. Thus, a condition for minimizing the noise when the valve is closed is to control the peak current integral value II in this dead zone.
Next, the reason why there is the dead zone 500 in
From the relationship between the speed of the anchor 204 at the time of valve closing and the time illustrated in the middle stage of
On the other hand, when the peak current width is shortened to 1.15 ms, 1.11 ms, 1.1 ms, or 1.095 ms, the anchor 204 starts to be decelerated from a timing (near 0.03 s to 0.0301 s) at which the electromagnetic actuator control device 113 cuts off the peak current Ia by the maximum current value Im. The anchor 204 coasts toward the fixing portion 206 at a low speed. For the peak current widths of 1.15 ms, 1.11 ms, and 1.1 ms, sections up to near 0.0306 s, 0.031 s, and 0.0316 s represent the coasting sections, respectively. When the peak current width is 1.095 ms, since the magnetic attraction force is insufficient, valve closing failure is caused from coasting.
When the anchor 204 approaches the fixing portion 206, the anchor 204 is accelerated again by the magnetic attraction force generated by the holding current Ib switched from the peak current Ia (for example, near 0.0306 s to 0.03075 s in the case of a peak current width of 1.15 ms indicated by a broken line). When the anchor 204 is re-accelerated by the magnetic attraction force Fmag by the holding current Ib from a state of substantially speed 0, the anchor 204 collides with the fixing portion 206 at a speed determined by a distance between the anchor 204 and the fixing portion 206 regardless of the method of the movement so far, and the suction valve 203 is closed. This is the reason why there is the dead zone 500 of the valve-closing-completion-immediately-preceding speed vel_Tb of the anchor 204 with respect to the peak current integral value II.
Since it has been found that there is the dead zone 500 in the relationship between the peak current integral value II and the valve-closing-completion-immediately-preceding speed vel_Tb, the horizontal axis of
As illustrated in
As described above, the present inventors have found that there is the saturation region Tr of the current I energized to the solenoid 205 in which the valve-closing-completion-immediately-preceding speed vel_Tb of the movable element (anchor 204) does not become small even though the current I flowing to the solenoid 205 is reduced. The fact that the valve-closing-completion-immediately-preceding speed vel_Tb of the movable element (anchor 204) is saturated means that the impact and noise at the time of valve closing, which are dominant by the valve-closing-completion-immediately-preceding speed, are saturated.
Referring back to
Thus, in the control device according to the present embodiment, control is performed such that the valve-closing-completion timing Tb enters the saturation region Tr illustrated in
In the control device of the related art disclosed in PTL 1, since the increase and decrease of the current application amount are repeated near the minimum current application amount with which the valve can be closed, the valve closing failure occurs once in several strokes. The valve closing failure causes pulsation of the fuel pressure. The pulsation of the fuel pressure causes the variation in the amount of fuel injected from the injector. However, in the control device according to the present embodiment, the valve closing failure is suppressed by energizing the peak current Ia to the solenoid 205 so as to have an appropriate current amount. Thus, the fuel pulsation of the high pressure fuel pipe from the high-pressure fuel pump 103 to the injector 105 can be reduced. When the fuel pulsation is reduced, the variation in the amount of fuel injected from the injector 105 can be suppressed.
As described with reference to
The phenomenon found by the present inventors has been described above in the control of the high-pressure fuel pump 103 in which the electromagnetic actuator control device 113 applies the peak current Ia and the holding current Ib to the solenoid 205 and switches from the peak current Ia to the holding current Ib before the closing of the suction valve 203 is completed. In the phenomenon, as described above, when the peak current integral value II is decreased, the valve-closing-completion-immediately-preceding speed vel_Tb also becomes small, but even though the peak current integral value II is smaller than the current application amount limit value, the decrease of the valve-closing-completion-immediately-preceding speed vel_Tb stops and the valve-closing-completion-immediately-preceding speed vel_Tb is saturated. Hereinafter, the control device according to the first to third embodiments capable of achieving the low noise of the high-pressure fuel pump based on the phenomenon in which the valve-closing-completion-immediately-preceding speed vel_Tb is saturated will be described. The control device according to each embodiment corresponds to the electromagnetic actuator control device 113 illustrated in
A control device 800 (see
In other words, the control device 800 controls the force of closing the suction valve 203 by performing control such that the peak current integral value II falls within the range of the dead zone 500.
As described above, the control device 800 (see
The control device 800 includes a current application amount storage unit 801 that stores a range of the current application amount of the peak current Ia for saturating the valve closing speed, a current application amount calculation unit 802 that calculates the current application amount of the peak current Ia, and a current control unit 803 that controls the current energized to the solenoid 205 based on the range of the current application amount of the peak current Ia and the current application amount of the peak current Ia.
The current application amount storage unit 801 stores the range of the current application amount of the peak current Ia for saturating the valve closing speed. This range is a range (an example is shown in the dead zone 500 in
In order for the current control unit 803 to control the current I, the current application amount calculation unit 802 calculates the current application amount by integrating the current I energized to the solenoid 205.
When the current application amount (peak current integral value II) to the solenoid 205 reaches any value (current application amount limit value) set in the range of the current application amount stored in the current application amount storage unit 801, the current control unit 803 switches from the peak current Ia to the holding current Ib. The current control unit 803 corresponds to the function of the power supply control circuit 306 illustrated in
The current I flowing through the solenoid 205 is taken into the control device 800 after processing such as conversion into a voltage by the shunt resistor 804 is performed.
The current application amount calculation unit 802 calculates the current application amount (peak current integral value II) by integrating the current I taken into the control device 800 (S901). The current application amount storage unit 801 stores, as the current application amount limit value, a value at a right end 501 of the dead zone 500 indicated by the relationship between the peak current integral value II and the valve-closing-completion-immediately-preceding speed vel_Tb illustrated in
Subsequently, the current control unit 803 compares the current application amount (peak current integral value II) calculated by the current application amount calculation unit 802 with the current application amount limit value stored in the current application amount storage unit 801 (S902). When the current application amount (peak current integral value II) does not exceed the current application amount limit value (YES in S902), the current control unit 803 executes peak current control such that the peak current Ia is maintained (S903). On the other hand, when the current application amount (peak current integral value II) exceeds the current application amount limit value (NO in S902), the current control unit 803 shifts from the peak current Ia to the application of the holding current Ib and executes holding current control (S904).
The control device 800 repeats the control of the flow illustrated in
The current control unit (power supply control circuit 306) of the control device 800 according to the first embodiment described above reduces the peak current Ia of the current I energized to the solenoid 205 before a timing at which the anchor 204 is attracted to the fixing portion 206 and collides. For example, the power supply control circuit 306 energizes the peak current Ia to the solenoid 205 until the valve-closing-completion timing Tb, and switches the control of the power supply 112 so as to reduce the peak current Ia before the valve-closing-completion timing Tb. At that time, the current control unit 803 reduces the peak current integral value II within the range of the dead zone 500 in which the valve-closing-completion-immediately-preceding speed vel_tb immediately before the anchor 204 collides with the fixing portion 206 does not change. Thus, the valve-closing-completion-immediately-preceding speed vel_tb becomes a constant value controlled within the dead zone 500, and the generation of the noise and the vibration at the time of driving the high-pressure fuel pump 103 is suppressed. Thus, the low noise of the high-pressure fuel pump 103 can be achieved.
Next, a configuration example and an operation example of a control device of a high-pressure fuel pump according to a second embodiment of the present invention will be described. The high-pressure fuel pump to be controlled in the present embodiment is the same as the high-pressure fuel pump to be controlled in the first embodiment. The control device according to the second embodiment controls the valve opening and closing of the high-pressure fuel pump by the peak current Ia and the holding current Ib in the same manner as the control performed by the control device according to the first embodiment. However, the control device of the high-pressure fuel pump according to the first embodiment controls the peak current integral value II such that the current application amount becomes smaller than the current application amount limit value as illustrated in
When the application amount of the peak current Ia is reduced from the value sufficient to close the high-pressure fuel pump 103, there is a relationship in which the valve-closing-completion timing Tb of the suction valve 203 is a constant value Tb_min until the current application amount of the peak current Ia reaches a predetermined value as illustrated in
The control device 800A of the high-pressure fuel pump 103 includes a saturated-valve-closing timing storage unit 1001 that stores a saturated-valve-closing timing, a valve-closing-completion timing detection unit 1002 that detects the valve-closing-completion timing Tb, and a current control unit 803 that controls the current application amount based on a relationship between the saturated-valve-closing timing and the valve-closing-completion timing Tb.
As illustrated in
The valve-closing-completion timing detection unit 1002 detects the valve-closing-completion timing Tb. The valve-closing-completion timing detection unit 1002 corresponds to the functions of the current measurement circuit 301, the differentiation circuit 302, the absolute value circuit 303, and the smoothing circuit 304 illustrated in
The current control unit 803 increases the current application amount to advance the valve-closing-completion timing Tb when the valve-closing-completion timing Tb becomes slower than a target value set slower than a certain value of the saturated-valve-closing timing stored in the saturated-valve-closing timing storage unit 1001, and decreases the current application amount to delay the valve-closing-completion timing Tb when the valve-closing-completion timing Tb is earlier than the target value. For example, as illustrated in
The current I flowing through the solenoid 205 is taken into the control device 800A after processing such as conversion into a voltage by the shunt resistor 804 is performed.
When the closing of the high-pressure fuel pump 103 is completed, a switching frequency of the current I flowing through the solenoid 205 changes due to a change in an inductance L. The valve-closing-completion timing detection unit 1002 recognizes, as the valve-closing-completion timing Tb, a timing at which the switching frequency of the current I changes by the method illustrated in
The current control unit 803 determines whether or not the valve-closing-completion timing Tb is earlier than the saturated-valve-closing timing (S1102).
When the valve-closing-completion timing Tb is slower than the saturated-valve-closing timing (NO in S1102), the current control unit 803 executes the peak current control for maintaining the peak current Ia (S1103), and returns to step S1101.
When the valve-closing-completion timing is earlier than the saturated-valve-closing timing (YES in S1102), the current control unit 803 shifts to the holding current control for applying the holding current Ib from the peak current Ia (S1104), and returns to step S1101.
Here, the saturated-valve-closing timing storage unit 1001 stores the relationship between the valve-closing-completion timing Tb and the valve-closing-completion-immediately-preceding speed vel_Tb illustrated in
When the valve-closing-completion timing Tb is larger (slower) than the target value Tb_tar larger than the constant value Tb_min, the current control unit 803 increases the peak current integral value II to advance the valve-closing-completion timing Tb. Conversely, when the valve-closing-completion timing Tb is smaller (earlier) than the target value Tb_tar, the current control unit 803 reduces the peak current integral value II to delay the valve-closing-completion timing Tb.
The control device 800A repeats the control of the flow illustrated in
Next, a configuration example and an operation example of a control device of a high-pressure fuel pump according to a third embodiment of the present invention will be described. The high-pressure fuel pump to be controlled in the present embodiment is the same as the high-pressure fuel pump to be controlled in the first embodiment. The control device according to the third embodiment controls the valve opening and closing of the high-pressure fuel pump by the peak current Ia and the holding current Ib in the same manner as the control performed by the control device according to the first embodiment. In the first embodiment, it is necessary to store information regarding the dead zone of the valve-closing-completion-immediately-preceding speed vel_Tb. However, in the third embodiment, since the control is performed based on the change in the valve-closing-completion timing Tb detected when the peak current integral value II changes, the storage regarding the dead zone is unnecessary. Specifically, control is performed based on the fact that when the peak current integral value II is larger than the maximum value of the peak current integral value II in the dead zone, the valve-closing-completion timing Tb is constant even though the peak current integral value II changes, but when the peak current integral value II is smaller than the maximum value of the peak current integral value II in the dead zone, the valve-closing-completion timing Tb also changes due to the change in the peak current integral value II. When the peak current integral value II gradually decreases from the peak current integral value II sufficiently larger than the peak current integral value II necessary for closing the valve, a point at which the valve-closing-completion timing Tb starts to change is recognized as an end point of the dead zone.
The control device 800B (see
The control device 800B includes a current application amount calculation unit 802 that calculates the current application amount, a valve-closing-completion timing detection unit 1002 that detects the valve-closing-completion timing Tb of the suction valve 203, and a change rate target value storage unit 1201 that stores a target value of the change rate. The control device 800B includes a change rate calculation unit 1202 that calculates a change rate indicated by ΔTb/ΔII from the current application amount calculated by the current application amount calculation unit 802 and the valve-closing-completion timing Tb detected by the valve-closing-completion timing detection unit 1002, and a current control unit 803 that controls the current I energized to the solenoid 205 such that the change rate calculated by the change rate calculation unit 1202 matches the target value of the change rate read from the change rate target value storage unit 1201.
The current application amount calculation unit 802 calculates the current application amount from the current energized to the solenoid 205 and outputs the peak current integral value II to the change rate calculation unit 1202.
The valve-closing-completion timing detection unit 1002 detects the valve-closing-completion timing Tb of the suction valve 203. The valve-closing-completion timing detection unit 1002 outputs the valve-closing-completion timing Tb to the change rate calculation unit 1202.
The change rate calculation unit 1202 calculates the change rate based on the change amount of the current application amount and the change amount of the valve-closing-completion timing Tb. For example, the change rate calculation unit 1202 calculates an actual change rate indicated by a ratio ΔTb/ΔII between a change amount ΔII of the peak current integral value II calculated by the current application amount calculation unit 802 and a change amount ΔTb of the valve-closing-completion timing Tb, and outputs the change rate to the current control unit 803. The change rate calculation unit 1202 corresponds to the function of the power supply control circuit 306 illustrated in
The change rate target value storage unit 1201 stores the change rate target value. The target value (for example, a negative value near zero) of the change rate is indicated by the ratio ΔTb/ΔII between the change amount ΔII of the peak current integral value II and the change amount ΔTb of the valve-closing-completion timing Tb as illustrated in
The current control unit 803 controls the current I energized to the solenoid 205 such that the change rate does not become smaller than the target value (for example, a negative value near zero) of the change rate read from the change rate target value storage unit 1201.
The control device 800B achieves low noise by gradually decreasing the peak current integral value II from the large value sufficient to close the high-pressure fuel pump 103, detecting the peak current integral value II appropriate for noise reduction, and performing control such that the peak current integral value II becomes this value. However, since the control device 800B cannot directly control the peak current integral value II, for example, the peak current integral value II is indirectly controlled by changing a peak holding time Th indicating a time for holding the peak current Ia from a large value to a small value. Hereinafter, a specific operation of the control device 800B will be described.
First, the control device 800B sets the peak holding time Th to a value Th_0 sufficient to close the high-pressure fuel pump 103. At this time, the current I flowing through the solenoid 205 is taken into the control device 800B after processing such as conversion into a voltage by the shunt resistor 804 is performed.
Subsequently, the current application amount calculation unit 802 integrates the current I taken into the control device 800B to calculate the current application amount (peak current integral value II) (S1301).
When the closing of the high-pressure fuel pump 103 is completed, the switching frequency of the current I flowing through the solenoid 205 changes due to the change in the inductance L of the solenoid 205. The valve-closing-completion timing detection unit 1002 detects the valve-closing-completion timing Tb based on the change in the switching frequency of the current I by the method illustrated in
In step S1302, the processing returns to first step S1301 for the first time (for example, at startup of the direct injection internal combustion engine 10). This is because a previous value (peak current integral value II or valve-closing-completion timing Tb) is required for the change rate calculation unit 1202 to calculate the change rate ΔTb/ΔII in step S1303.
Here, a procedure in which the control device 800B sets an initial value of the peak current integral value II to II0, sets an initial value of the valve-closing-completion timing Tb to Tb0, and searches for the saturation region Tr will be described.
As illustrated in
The initial value II0 is set to the large value sufficient to close the high-pressure fuel pump. The initial value Tb0 is a valve closing timing when the current application amount is II0.
Referring back to
After first steps S1301 and S1302, the change rate calculation unit 1202 increases the peak holding time Th by a preset step width ΔTh, and re-executes steps S1301 and S1302 to calculate the peak current integral value II and the valve-closing-completion timing Tb.
The change rate calculation unit 1202 calculates the change amount ΔII (difference of the peak current integral value II) of the peak current integral value II by subtracting the initial value II0 from the peak current integral value II. The change rate calculation unit 1202 calculates the change amount ΔTb (difference of the valve-closing-completion timing Tb) of the valve-closing-completion timing Tb by subtracting the initial value Tb0 from the valve-closing-completion timing Tb. Thereafter, the change rate calculation unit 1202 calculates, as the change rate ΔTb/ΔII, a ratio of the change amount ΔTb to the calculated change amount ΔII (S1303).
The current control unit 803 determines whether or not the change rate ΔTb/ΔII calculated in step S1305 is smaller than the change rate target value stored in the change rate target value storage unit 1201 (S1304). When the change rate ΔTb/ΔII is smaller than the change rate target value (YES in S1304), since the valve closing is not completed, the current control unit 803 executes the peak current control such that the peak current Ia is maintained (S1305), and returns to step S1301.
On the other hand, when the change rate ΔTb/ΔII is equal to or more than the change rate target value (NO in S1304), since the valve closing is completed, the current control unit 803 shifts to the holding current control in which the holding current Ib is applied from the peak current Ia (S1306).
As described above, the current control unit 803 of the control device 800B executes the peak current control or the holding current control in a switched manner according to the relationship between the change rate ΔTb/ΔII and the change rate target value. That is, since the control device 800B can perform control such that the relationship between the peak current integral value II and the valve-closing-completion timing Tb falls within the saturation region Tr, the low noise of the high-pressure fuel pump 103 can be achieved. As described above, the valve closing failure causes the pulsation of the fuel pressure, and the pulsation of the fuel pressure causes the variation in the amount of fuel injected from the injector 105. However, in the method according to the present embodiment, since the peak current control and the holding current control can be realized without searching for the valve closing limit, the pressure pulsation of the fuel discharged to the high pressure pipe 104 due to the valve closing failure does not occur.
Hitherto, it has been described that the low noise of the high-pressure fuel pump 103 can be achieved by the control device according to the first to third embodiments executing the peak current control and the holding current control at an appropriate timing. However, in order for the control device according to each embodiment to realize control for maintaining the valve-closing-completion timing Tb within the range of the common saturation region Tr, it is necessary to accurately detect the valve-closing-completion timing Tb. Hereinafter, a method for detecting, by each circuit of the electromagnetic actuator control device 113 illustrated in
A timing at which an amplitude of the output signal of the vibration sensor rapidly increases (position of 33.6 ms) illustrated in the graph 1502 represents the valve-closing-completion timing Tb. It can be seen that a change occurs in a density (the number of lines per unit time) of a switching waveform of the current I shown in the graph 1501 so as to correspond to the valve-closing-completion timing Tb. When a portion where the density of the switching waveform changes is enlarged, a change in the switching frequency can be seen. There is a time difference between an amplitude sudden increase timing of the vibration sensor and a change timing of the switching frequency, and this time difference is a time required for the vibration due to the valve closing completion to be transmitted to the vibration sensor.
The reason why the switching frequency changes due to the valve closing completion will be considered below. The power supply control circuit 306 of the electromagnetic actuator control device 113 according to the present embodiment illustrated in
Switching voltages V+ and V- and the current I have the following relationships (2) and (3).
Equation (2) shows a relationship between the switching voltage V+ and the current I when the current I rises. Equation (3) shows a relationship between the switching voltage V- and the current I when the current I falls. Since the range of the current I at the time of switching control is limited, it is considered that right sides of Equations (2) and (3) are substantially constant. When the anchor 204 approaches the fixing portion 206 by the valve closing, since the inductance L becomes small, an absolute value of dI/dt = (V - RI)/L becomes large. As a result, the slope of the current I becomes steep, and the frequency becomes high. This is the reason why the switching frequency changes. In the normal control of the high-pressure fuel pump 103, V+ is 14 V as a battery voltage, and V-is 0 V as a ground voltage.
As described above, the switching frequency of the current I changes before and after the valve-closing-completion timing Tb. The electromagnetic actuator control device 113 according to the first to third embodiments performs control such that the timing at which the switching frequency corresponding to the valve-closing-completion timing Tb changes belongs to the common saturation region Tr (see
This set range is set to be the saturation region Tr (dead zone 500 illustrated in
There is a correlation between the speed of the anchor 204 when the high-pressure fuel pump 103 is closed (timing when the anchor 204 collides with the fixing portion 206) and the noise due to impact between the anchor 204 and the fixing portion 206 or collision between the anchor 204 and the fixing portion 206 when the valve is closed. Thus, the set range (common saturation region Tr) may be set to be the saturation region Tr (dead zone 500 in
The magnitude of the noise is proportional to the square of the speed when the anchor 204 collides with the fixing portion 206. Thus, the above set range may be set to be the saturation region (dead zone 500 in
Specifically, the current I flowing through the solenoid 205 indicates a current integral value from the start of supply (timing t1) of the peak current Ia to the start of reduction (timing t3) of
Thus, it is desirable that the power supply control circuit 306 controls the peak current Ia such that the peak current integral value II calculated from the current integral value from the start of supply (timing t1) to the start of reduction (timing t3) flowing to the solenoid 205, the maximum current value Im of the peak current Ia, or the period (peak current width Th) in which the maximum current value Im flows falls within the saturation region Tr (dead zone 500 in
As described above, it has been found that the low noise of the high-pressure fuel pump 103 can be achieved by the power supply control circuit 306 controlling the peak current integral value II based on the change in the switching frequency. The next problem is to detect this change in switching frequency. In order to capture the change in the switching frequency, processing is performed in a flow illustrated in
As illustrated in a graph
The differentiation circuit 302 differentiates the voltage signal converted by the current measurement circuit 301 (S1601). A result of differentiating the voltage signal by the differentiation circuit 302 is represented by a waveform as illustrated in a graph
Since the differentiation result differs between the rising and the falling, a value corresponding to the switching frequency is obtained by sampling near an end of the rising in synchronization with the switching of the current I. However, this sampling applies a load to a microcomputer (hereinafter, abbreviated as “microcomputer”) used as the power supply control circuit 306. Thus, the absolute value circuit 303 illustrated in
The absolute value circuit 303 is a circuit that outputs an absolute value of an input signal. The absolute value of the differentiation result output from the absolute value circuit 303 is represented by a waveform as illustrated in a graph
As illustrated in the graph (3), the absolute value also changes before and after the valve-closing-completion timing Tb. Thus, the smoothing circuit 304 smooths an output (absolute value) of the absolute value circuit 303 with a time constant longer than the switching cycle based on the switching frequency of the current I (S1603). A signal illustrated in a graph
As described above, the electromagnetic actuator control device 113 according to the first to third embodiments illustrated in
This method may be performed by an analog circuit until the signal is smoothed. Thereafter, when a function of performing AD conversion on the smoothed waveform illustrated in the graph
Thus, an embodiment in which the valve-closing-completion timing Tb can be detected when there is a margin in the processing capacity of the microcomputer (power supply control circuit 306) will be described with reference to
The filter 310 according to the present embodiment is a circuit used in place of the differentiation circuit 302, the absolute value circuit 303, and the smoothing circuit 304 included in the electromagnetic actuator control device 113 illustrated in
When the switching current signal before and after the collision as illustrated in a graph
As in the graph
The amplitude of the current I input to the filter 310 is substantially the same before and after the collision between the anchor 204 and the fixing portion 206, but there is a relationship shown in Equation (5) between an amplitude a_bef of the output signal before the collision and an amplitude a_aft after the collision.
As described above, since the gain of the filter 310 is different before and after collision, when signals having the same amplitude are input to the filter 310, a difference in gain becomes a difference in output, and thus, the relationship shown in Equation (5) appears. Thus, when the amplitude of the current I is extracted, a change in the output signal illustrated in the graph
When the electromagnetic actuator control device 113 obtains the absolute value of the output signal and smooths the absolute value with the filter 310 having a cutoff frequency lower than the switching frequency, a change appears in the frequency of the output signal as illustrated in the graph
In the embodiment described so far, the gain before and after the collision is expressed by the above-described Equation (4). However, the gain before and after the collision may be expressed by Equation (6).
It is also considered that the frequencies before and after the collision are distributed in a certain range illustrated in
Here, when the suction valve 203 of the high-pressure fuel pump 103 is closed, the inductance L in the magnetic circuit between the anchor 204 and the fixing portion 206 changes. As illustrated in
The amplitude of the current I is controlled to be constant before and after the suction valve 203 is closed. Thus, when a filter having a different gain is used with respect to the switching frequency before and after valve closing, the amplitude of the current I after filtering is different before and after valve closing. Thus, the control device (electromagnetic actuator control device 113) of the high-pressure fuel pump 103 according to the first to third embodiments can detect the valve-closing-completion timing Tb of an electromagnetic actuator 200 by extracting the amplitude of the current I and specifying the change point of the amplitude.
Here, a configuration example and an operation example of the valve-closing-completion timing detection unit that detects the valve-closing-completion timing Tb based on a change in the amplitude of the current I will be described with reference to
A control device 800C of the high-pressure fuel pump 103 according to the present embodiment includes the valve-closing-completion timing detection unit 1002A in addition to the current control unit 803 and the saturated-valve-closing timing storage unit 1001 described above.
The valve-closing-completion timing detection unit 1002A may be provided in the control device according to each embodiment instead of the valve-closing-completion timing detection unit 1002 according to the second and third embodiments described above. The valve-closing-completion timing detection unit 1002A includes a current measurement unit 2201, a filter 310, and an amplitude extraction unit 2202.
The current measurement unit 2201 measures the current I flowing through the solenoid 205. Thus, the current measurement unit 2201 has a function corresponding to an analog-to-digital (AD) converter.
The filter 310 has different gain characteristics from the switching frequency of the current measured before and after the suction valve 203 shifts to the valve closing state. For example, the filter 310 has different gain characteristics from the frequency of the current I before and after the timing at which the mover (anchor 204) collides with the fixing portion 206.
The amplitude extraction unit 2202 extracts the amplitude of the output obtained from the filter 310 to which the current I is input, and detects the change point of the amplitude as the valve-closing-completion timing Tb.
The current measurement unit 2201 measures the current I flowing through the solenoid 205 (S2301).
Subsequently, the current signal of the current I flowing through the solenoid 205 measured by the current measurement unit 2201 is filtered by the filter 310 having the gain different between the frequency after the valve closing and the frequency before the valve closing (S2302).
The amplitude extraction unit 2202 extracts a component of the switching current signal from the filtering result (S2303) .
The valve-closing-completion timing detection unit 1002A estimates a timing at which the movable element (anchor 204) collides with the fixing portion 206 based on the change in the amplitude output from the amplitude extraction unit 2202. That is, the valve-closing-completion timing detection unit 1002A can detect the valve-closing-completion timing Tb of the electromagnetic actuator 200 by estimating the collision timing.
As described with reference to
Thus, the power supply control circuit 306 (current control unit 803) of the electromagnetic actuator control device 113 reduces the current I given to the solenoid 205 of the high-pressure fuel pump 103. When the valve-closing-completion timing Tb is delayed, the electromagnetic actuator control device 113 controls the current I such that the valve-closing-completion timing Tb detected by the valve-closing-completion timing detection unit 1002A belongs to the common saturation region Tr that does not depend on the valve-closing-completion-immediately-preceding speed vel_Tb or the variation in the individual characteristics of the saturation region Tr when the noise is saturated. The current I is controlled by the electromagnetic actuator control device 113 in this manner, and thus, the low noise of the high-pressure fuel pump 103 can be achieved.
The present invention is not limited to the above-described embodiments, and various other application examples and modification examples can be acquired without departing from the gist of the present invention described in the claims.
For example, the above-described embodiments are to describe the configurations of the devices and the systems in detail in order to facilitate easy understanding of the present invention, and do not necessarily include all the described configurations. A part of the configurations of the embodiments described herein can be replaced with configurations of other embodiments, and the configurations of other embodiments can be added to the configuration of one embodiment. Additions, the components of another embodiment can be added, removed, and substituted to, from, and into some of the components of the aforementioned embodiments.
Furthermore, control lines and information lines illustrate lines which are considered to be necessary for the description, and not all the control lines and information lines in a product are necessarily illustrated. Almost all the configurations may be considered to be actually connected to each other.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-033341 | Feb 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/048695 | 12/25/2020 | WO |
