JP5633422B2 - Accumulated fuel injection system - Google Patents

Description

  The present invention relates to a pressure accumulation type fuel injection device that controls the amount of oil fed from a high pressure fuel supply pump to a common rail in which high pressure fuel is accumulated by a pressure control valve.

  Conventionally, as disclosed in Patent Document 1, in an accumulator fuel injection device that supplies fuel from a common rail to a fuel injection valve, high pressure fuel is supplied from a high pressure fuel supply pump to the common rail, and a high pressure fuel supply pump is provided by a pressure control valve. The fuel pressure of the common rail is controlled by adjusting the amount of oil fed from the tank.

  At that time, pre-stroke control is performed in the middle of the compression stroke of the plunger type high pressure fuel supply pump to close the pressure control valve and supply high pressure fuel to the common rail to control the fuel pressure of the common rail. In addition, the common rail fuel pressure is detected by a sensor, and the energization timing to the pressure control valve is feedback controlled so that the difference between the fuel pressure and the target pressure becomes small based on the detected fuel pressure and the target pressure. Yes.

JP-A-5-163994

  In such a conventional system, the pressure control valve is closed by outputting a drive signal to the pressure control valve at the time of energization. When the pressure control valve is closed, the pressure of the high-pressure fuel is received in the valve closing direction to maintain the valve closed state.

  For example, as shown in FIG. 11A, a drive signal is output to the pressure control valve to supply high-pressure fuel from the high-pressure fuel supply pump to the common rail. The drive signal at this time is set to a predetermined fixed period in consideration of the responsiveness of the pressure control valve, and energy saving is achieved without unnecessarily lengthening the energization period.

  Then, as shown in FIG. 11B, when the response of the pressure control valve becomes slow due to secular change or the like, the energization timing of the drive signal is controlled to the advance side by feedback control, and the common rail pressure is controlled to the target pressure. ing.

  However, the inventors have clarified that the following problems occur as the response of the pressure control valve further deteriorates. That is, there is a problem that the valve cannot be closed when the response time of the pressure control valve becomes long enough to exceed the energization period of the solenoid. That is, as shown in FIG. 11 (c), the valve body of the pressure control valve is sufficiently lifted even when the energization timing of the drive signal is advanced or the energization period ends according to the deterioration of responsiveness. The full lift position (valve closing position) may not be reached. In this case, the pressure control valve cannot be closed completely, and high pressure fuel may not be supplied from the high pressure fuel supply pump. For this reason, there is a problem that the high-pressure fuel supply from the high-pressure fuel supply pump cannot be reliably maintained.

  An object of the present invention is to provide a pressure accumulation type fuel injection device capable of maintaining the supply of high pressure fuel even when the responsiveness of a pressure control valve is deteriorated.

In order to achieve this problem, the present invention has taken the following measures in order to solve the problem. That is,
A fuel injection valve for injecting fuel into a cylinder of the internal combustion engine;
A common rail that holds fuel accumulated at a high pressure and supplies the fuel to the fuel injection valve;
A high pressure fuel supply pump for supplying high pressure fuel to the common rail;
The high-pressure fuel is supplied from the high-pressure fuel supply pump to the common rail by closing the drive signal, and the pressure of the high-pressure fuel is received in the valve closing direction to maintain the valve closed. A pressure control valve to control the supply;
Fuel pressure detecting means for detecting the fuel pressure of the common rail,
Accumulated pressure for controlling the fuel pressure of the common rail by controlling the pressure control valve by the drive signal according to the energization timing based on the fuel pressure detected by the fuel pressure detecting means and the target pressure and a preset energization period. In the fuel injection device,
Compensating means is provided for calculating a responsiveness deterioration amount of the pressure control valve based on the energization timing and changing the energization period to the pressure control valve longer based on the responsiveness deterioration amount. This is an accumulator fuel injection device.

Said correcting means, said calculating the response deterioration amount based on the energization time change in the feedback control based on said target pressure and the fuel pressure, this time, of the energizing time of the feedback control correction amount of The responsiveness deterioration amount may be calculated based on the change of the integral term.

  Further, the correction means is based on the energization timing in the feedback control and the energization timing corresponding to the oil supply amount calculated based on the change in the fuel pressure of the common rail detected by the fuel pressure detection means. The responsiveness deterioration amount may be calculated. At this time, the correction means may calculate the responsiveness deterioration amount during open control.

The correction means may change the energization period longer based on the responsiveness deterioration amount so that a ratio between the response time of the pressure control valve and the energization period becomes constant. Alternatively, the correction unit may add the responsiveness deterioration amount to change the energization period longer.

  The pressure accumulation type fuel injection device of the present invention calculates the responsiveness deterioration amount of the pressure control valve, and changes the energization period of the pressure control valve based on the responsiveness deterioration amount, so that the energization period is unnecessarily extended. There is an effect that the supply of high-pressure fuel can be maintained even when the responsiveness of the pressure control valve is deteriorated while saving energy.

  By calculating the responsiveness deterioration amount based on the change in the energization timing for feedback control, the responsiveness deterioration amount can be easily calculated quantitatively. Further, by calculating the responsiveness deterioration amount based on the change of the integral term of the correction amount of the energization time, it is possible to catch the responsiveness deterioration due to the change with time.

  In addition, the responsiveness deterioration amount can be easily quantified by calculating the responsiveness deterioration amount based on the energization timing in feedback control and the energization timing corresponding to the oil supply amount calculated based on the change in the fuel pressure of the common rail. Can be calculated automatically. In that case, it can calculate correctly by calculating the amount of responsiveness deterioration at the time of open control.

  Furthermore, the energization period can be easily changed by adding the responsiveness deterioration amount and changing the energization period longer. Alternatively, energy saving can be further achieved by changing the energization period so that the ratio between the response time and the energization period is constant.

1 is an overall configuration diagram showing a pressure accumulation type fuel injection device as one embodiment of the present invention. It is explanatory drawing of the pressure control valve and drive signal of this embodiment. It is a block diagram which shows the control logic of the feedback control of this embodiment. It is a graph which shows the relationship between the integral term and responsiveness deterioration degree of this embodiment. It is a graph which shows the relationship between the oil supply amount of the pressure control valve of this embodiment, and energization timing. It is a flowchart which shows an example of the responsiveness deterioration correction process performed in the electronic control circuit of this embodiment. It is a timing chart of the drive signal of a pressure control valve of this embodiment, a valve lift, and a pump cam. It is a flowchart which shows an example of the responsiveness deterioration correction process performed in the electronic control circuit of another embodiment. It is a graph which shows the relationship between the oil supply amount of the pressure control valve of another embodiment, and energization timing. It is a timing chart of the drive signal of a pressure control valve of another embodiment, a valve lift, and a pump cam. It is a timing chart of the drive signal of a conventional pressure control valve, a valve lift, and a pump cam.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is an overall configuration diagram showing a pressure accumulation type fuel injection device as one embodiment of the present invention.
As shown in FIG. 1, the pressure accumulation type fuel injection device of the present embodiment is applied to, for example, an internal combustion engine 1 as a four-cylinder diesel engine, and a common rail 2 that stores high-pressure fuel and a feed pump from a fuel tank 3. A high-pressure fuel supply pump 4 that pressurizes the fuel pumped up by 10 and supplies it to the common rail 2 and a fuel that injects high-pressure fuel supplied from the common rail 2 through the high-pressure pipe 17 into the combustion chamber 21 in the cylinder of the internal combustion engine 1. An injection valve 5 and an electronic control unit 6 (hereinafter referred to as ECU 6) for electronically controlling the fuel injection valve 5 and the like are provided.

  The common rail 2 has a target pressure set by the ECU 6 based on the operating state and the like, and accumulates the high-pressure fuel supplied from the high-pressure fuel supply pump 4 to the target pressure. A fuel pressure sensor 7 is attached to the common rail 2 as fuel pressure detecting means for detecting the accumulated fuel pressure and outputting it to the ECU 6.

  As shown in FIG. 2, the high-pressure fuel supply pump 4 is driven by the internal combustion engine 1 and rotated by a cam 24 to reciprocate a piston 28 via a roller 26 to pressurize the fuel fed from the feed pump 10. The fuel is sucked into the chamber 30, and the fuel pressurized from the pressurizing chamber 30 is configured to push the discharge valve 32 and supply it to the common rail 2.

  The high-pressure fuel supply pump 4 is provided with a pressure control valve 34. The pressure control valve 34 slides the valve body 36 by exciting a solenoid (not shown) to be seated on the valve seat 38 and closes the valve. Further, the valve body 36 receives the fuel pressure in the pressurizing chamber 30 in the valve closing direction and maintains the valve closed state. The valve body 36 acts by the negative pressure of the pressurizing chamber 30 and the biasing force of a biasing member such as a spring (not shown). The valve body 36 is separated from the valve seat 38 and opened by, for example.

  A drive signal for a preset energization period Tss is input to the pressure control valve 34, and the solenoid is excited. The drive signal is input at a predetermined energization timing during the compression stroke of the high-pressure fuel supply pump 4 and is seated on the valve seat 38 by the valve lift of the valve body 36 by excitation of the solenoid to close the valve. When the pressure control valve 34 is closed, the high pressure fuel from the pressurizing chamber 30 is supplied to the common rail 2, and the amount of oil supplied from the high pressure fuel supply pump 4 to the common rail 2 can be varied by changing the energization timing. The fuel pressure of the common rail 2 can be controlled.

  Even if the energization period Tss to the pressure control valve 34 elapses during the compression stroke of the high-pressure fuel supply pump 4 and the excitation of the solenoid is stopped, the valve body 36 receives the fuel pressure in the pressurizing chamber 30 and receives the valve seat. When the high-pressure fuel supply pump 4 changes from the compression stroke to the suction process while the valve-closing state seated on the valve 38 is maintained, the valve body 36 opens away from the valve seat 38. Thereby, the fuel from the feed pump 10 is sucked into the pressurizing chamber 30.

  As described above, after the fuel is sucked into the pressurizing chamber 30, even if the piston 28 shifts to the compression stroke, the pressure control valve 34 is not immediately closed and the fuel in the pressurizing chamber 30 reaches a predetermined amount. Pre-stroke control is performed to hold the valve open, discharge excess fuel, and adjust the amount of oil delivered during supply. Since the closed state is maintained by the fuel pressure after the valve is closed, the energization period Tss is set in advance to a minimum period in consideration of the basic response time TFD of the pressure control valve 34 to save energy. .

  Each sensor is connected to an ECU 6, and the ECU 6 is configured as a logical operation circuit around a known CPU 62, ROM 64, RAM 66, etc., as shown in FIG. Here, the input / output circuits 68 are connected to each other via a common bus 70.

  The CPU 62 includes a fuel pressure sensor 7, a rotation sensor 18 using an electromagnetic pickup that detects a plurality of teeth formed on the pulsar 16, and an accelerator opening sensor 20 that detects an accelerator opening corresponding to the amount of depression of the accelerator pedal 19. Are input via the input / output circuit 68.

  Based on these signals, data in the ROM 64 and RAM 66 and a control program stored in advance, the CPU 62 is in an operating state such as the number of revolutions detected by the rotation sensor 18 and the accelerator opening detected by the accelerator opening sensor 20. Based on this, the injection amount and injection timing from the fuel injection valve 5 are calculated. Further, the target pressure of the common rail 2 is calculated based on the rotation speed and the injection amount, and the amount of oil supplied from the high-pressure fuel supply pump 4 to the common rail 2 is calculated based on the injection amount and the target pressure of the common rail 2. .

  When calculating the amount of oil to be fed, feedback control is performed as shown in the control logic of FIG. 3, and the pressure deviation ΔP between the fuel pressure of the common rail 2 detected by the fuel pressure sensor 7 and the target pressure is calculated. calculate. A proportional term used for the correction amount of the feedback control is calculated by multiplying the proportional gain Kp by the pressure deviation ΔP. Next, the integral term is calculated by multiplying the integral gain Ki by the integral value of the pressure deviation ΔP between the fuel pressure and the target pressure. Subsequently, the proportional term and the integral term are added to the command oil supply amount and output to the pressure control valve 34, and the pressure control valve 34 is feedback-controlled.

As shown in the following equation (1), feedback control by PID control in which a differential term obtained by multiplying the correction amount by the differential gain Kd and the differential value of the pressure deviation ΔP may be performed.
Correction amount = Kp × ΔP + Ki × ∫ΔP + Kd × d / dtΔP (1)
When the responsiveness of the pressure control valve 34 decreases due to a change over time or the like, the integral term of the correction amount increases. As shown in FIG. 4, in particular, the integral term during steady operation in which the load is in a constant operation state. And the degree of responsiveness deterioration of the pressure control valve 34 are proportional.

  Further, the relationship between the oil feed amount Q to the common rail 2 and the pressure change amount ΔP in the common rail 2 can be calculated by the following equation (2). Here, VCR is the volume of the common rail 2, and K is the bulk elastic modulus of the fuel in the common rail 2.

Q = ΔP × VCR / K (2)
On the other hand, as indicated by a solid line in FIG. 5, the relationship between the oil supply amount Q and the energization timing TF to the pressure control valve 34 is stored in advance, and based on this relationship, the oil supply amount Q is changed to the pressure control valve 34. The energization time TF is calculated.

Next, responsiveness deterioration processing as correction means executed by the ECU 6 will be described based on the flowchart shown in FIG.
First, based on the number of revolutions detected by the rotation sensor 18, the accelerator opening detected by the accelerator opening sensor 20, the fuel pressure of the common rail 2 detected by the fuel pressure sensor 7, etc., the current operating state is recognized. (Step 100, hereinafter referred to as S100, and so on). Next, based on the recognized driving state, it is determined whether or not it is in a steady state (S110). The steady state is a driving state where the vehicle travels on a flat road at a constant speed, the rotational speed is substantially constant, the accelerator opening is also substantially constant, the fuel pressure fluctuation of the common rail 2 is small, and the target pressure of the common rail 2 is small. And the amount of oil sent is almost constant. When in a steady state, there is no load fluctuation and the change in the fuel pressure of the common rail 2 is small.

  When it is determined that it is not in a steady state (S110: NO), this control process is temporarily terminated, and when it is determined that it is in a steady state (S110: YES), based on recognition of the integral term of the feedback control correction amount. The responsiveness deterioration amount ΔT is calculated (S120).

  As shown in FIG. 5, when the responsiveness of the pressure control valve 34 deteriorates, the oil feed amount ΔQ decreases at the same energization timing TF1. In order to maintain the same oil feed amount, the feedback control is advanced to the energization timing TF2 when the responsiveness deteriorates with respect to the normal energization timing TF1 when the pressure control valve 34 is new. The deterioration angle amount ΔTF obtained by advancing the energization timing TF2 when the responsiveness deteriorates with respect to the normal energization timing TF1 can be calculated by the following equation (3).

△ TF = TF1-TF2 (3)
The normal energization timing TF1 is stored during normal steady operation, and the deterioration angle amount ΔTF is calculated by the equation (3) during normal operation, so that the deterioration angle amount ΔTF corresponds to the correction amount of the integral term. The deterioration angle amount ΔTF corresponds to the deterioration of the responsiveness of the pressure control valve 34. Further, the deterioration angle amount ΔTF may be directly calculated from the integral term of the feedback control.

  Next, the responsiveness deterioration amount ΔT is calculated from the deterioration angle amount ΔTF by the following equation (4). Here, Np is the rotation speed (rpm) of the cam 24 of the high-pressure fuel supply pump 4 and converts the deterioration angle amount ΔTF whose angle is a unit into time.

ΔT = ΔTF / ((Np / 60) × 360)) (4)
Next, this responsiveness deterioration amount ΔT is added to the energization period Tss, and the corrected energization period Tssb is calculated by the following equation (5) (S130).

Tssb = Tss + ΔT (5)
By controlling the pressure control valve 34 with the corrected energization period Tssb in which the energization period Tss is increased by the responsiveness deterioration amount ΔT, as shown in FIG. 7, the energization period of the drive signal becomes longer and the responsiveness deteriorates. Even in the pressure control valve 34, the valve body 36 is securely seated on the valve seat 38 and is closed, and high-pressure fuel is supplied from the high-pressure fuel supply pump 4 to the common rail 2. Therefore, the supply of high-pressure fuel can be maintained even when the responsiveness of the pressure control valve 34 is deteriorated while saving energy without unnecessarily extending the energization period.

  The correction energization period Tssb is not limited to the case where the responsiveness deterioration amount ΔT is added to the energization period Tss, and is as follows so that the ratio between the basic response time TFD of the pressure control valve 34 and the energization period Tss becomes constant. ) May be used to calculate the correction energization period Tssb.

TFD / Tss = (ΔT + TFD) / Tssb = constant (6)
Next, responsiveness deterioration processing as a correction unit according to another embodiment different from the responsiveness deterioration processing described above will be described with reference to the flowchart of FIG.

  First, it is determined whether or not it is during open control (S200). At the time of start-up or inspection mode, a drive pulse of a preset energization time TFa is input to the pressure control valve 34 so as to obtain a preset designated oil feed amount, and open control is performed. During open control, a constant amount of oil is supplied to the common rail 2, there is no load fluctuation, and the change in the fuel pressure of the common rail 2 is small.

  When it is not at the time of open control (S200: NO), this control process is once ended, and at the time of open control (S200: YES), as shown in FIG. 9, the energization timing TFa at the designated oil feed amount is recognized (S210). . Next, the actual oil supply amount at the time of open control is calculated (S220).

  As shown in FIG. 10, the actual oil supply amount Q is detected by the fuel pressure sensor 7 by detecting the pressure change amount ΔP of the common rail 2 when the drive signal is output to the pressure control valve 34 during the open control and the valve is closed. The pressure change amount ΔP is calculated from the above-described equation (2).

  Then, the energization timing TFb corresponding to the calculated actual oil supply amount Q is calculated from the relationship between the normal oil supply amount and the energization timing shown by the solid line in FIG. 9 (S230). Subsequently, the deterioration angle amount ΔTF is calculated by subtracting the energization timing TFb at the actual oil supply amount from the energization timing TFa at the designated oil supply amount, as shown in the following equation (7). When the responsiveness of the pressure control valve 34 deteriorates, the actual oil supply amount Q decreases with respect to the designated oil supply amount, so the deterioration angle amount ΔTF corresponds to the deterioration of the responsiveness of the pressure control valve 34.

ΔTF = | TFa−TFb | (7)
Next, the responsiveness deterioration amount ΔT obtained by converting the deterioration angle amount ΔTF into time is calculated from the deterioration angle amount ΔTF by the above-described equation (4) (S240). The responsive deterioration amount ΔT is added to the energization period Tss, and the corrected energization period Tssb is calculated by the above-described equation (5) (S250). Alternatively, the corrected energization period Tssb may be calculated by equation (6) so that the ratio between the basic response time TFD of the pressure control valve 34 and the energization period Tss is constant.

  Similarly to the above-described embodiment, even in the pressure control valve 34 in which the energization period of the drive signal is long and the responsiveness is deteriorated, the valve body 36 is securely seated on the valve seat 38 and is closed, and the high pressure fuel supply pump 4 High pressure fuel is supplied to the common rail 2. Therefore, the supply of high-pressure fuel can be maintained even when the responsiveness of the pressure control valve 34 is deteriorated while saving energy without unnecessarily extending the energization period.

  The present invention is not limited to such embodiments as described above, and can be implemented in various modes without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Common rail 3 ... Fuel tank 4 ... High pressure fuel supply pump 5 ... Fuel injection valve 6 ... Electronic control unit 7 ... Fuel pressure sensor 10 ... Feed pump 17 ... High pressure piping 18 ... Rotation sensor 20 ... Accelerator opening sensor DESCRIPTION OF SYMBOLS 21 ... Combustion chamber 24 ... Cam 26 ... Roller 28 ... Piston 30 ... Pressurization chamber 32 ... Discharge valve 34 ... Pressure control valve 36 ... Valve body 38 ... Valve seat

Claims (7)

A fuel injection valve for injecting fuel into a cylinder of the internal combustion engine;
A common rail that holds fuel accumulated at a high pressure and supplies the fuel to the fuel injection valve;
A high pressure fuel supply pump for supplying high pressure fuel to the common rail;
The high-pressure fuel is supplied from the high-pressure fuel supply pump to the common rail by closing the drive signal, and the pressure of the high-pressure fuel is received in the valve closing direction to maintain the valve closed. A pressure control valve to control the supply;
Fuel pressure detecting means for detecting the fuel pressure of the common rail,
Accumulated pressure for controlling the fuel pressure of the common rail by controlling the pressure control valve by the drive signal according to the energization timing based on the fuel pressure detected by the fuel pressure detecting means and the target pressure and a preset energization period. In the fuel injection device,
A responsiveness deterioration amount of the pressure control valve is calculated based on a change of an integral term of a correction amount of the energization timing for feedback control based on the fuel pressure and the target pressure, and the responsiveness deterioration amount is calculated as the responsiveness deterioration amount. A pressure-accumulation fuel injection apparatus comprising: a correction unit that changes the energization period of the pressure control valve to be longer. A fuel injection valve for injecting fuel into a cylinder of the internal combustion engine;
A common rail that holds fuel accumulated at a high pressure and supplies the fuel to the fuel injection valve;
A high pressure fuel supply pump for supplying high pressure fuel to the common rail;
The high-pressure fuel is supplied from the high-pressure fuel supply pump to the common rail by closing the drive signal, and the pressure of the high-pressure fuel is received in the valve closing direction to maintain the valve closed. A pressure control valve to control the supply;
Fuel pressure detecting means for detecting the fuel pressure of the common rail,
Accumulated pressure for controlling the fuel pressure of the common rail by controlling the pressure control valve by the drive signal according to the energization timing based on the fuel pressure detected by the fuel pressure detecting means and the target pressure and a preset energization period. In the fuel injection device,
Based on the energization timing for feedback control based on the fuel pressure and the target pressure, and the energization timing corresponding to the oil supply amount calculated based on the change in the fuel pressure of the common rail detected by the fuel pressure detection means. A pressure accumulating fuel injection apparatus, comprising: a correction means for calculating a responsiveness deterioration amount of the pressure control valve and changing the energization period to the pressure control valve based on the responsiveness deterioration amount. . The pressure-accumulation fuel injection device according to claim 2 , wherein the correction means calculates the responsiveness deterioration amount during open control. The pressure-accumulation fuel injection device according to any one of claims 1 to 3 , wherein the correction means adds the responsiveness deterioration amount to change the energization period longer. The said correction | amendment means changes the said electricity supply period long based on the said responsiveness deterioration amount so that the ratio of the response time of the said pressure control valve and the said electricity supply period may become fixed. The pressure accumulation type fuel injection device according to claim 3 . A fuel injection valve for injecting fuel into a cylinder of the internal combustion engine;
A common rail that holds fuel accumulated at a high pressure and supplies the fuel to the fuel injection valve;
A high pressure fuel supply pump for supplying high pressure fuel to the common rail;
The high-pressure fuel is supplied from the high-pressure fuel supply pump to the common rail by closing the drive signal, and the pressure of the high-pressure fuel is received in the valve closing direction to maintain the valve closed. A pressure control valve to control the supply;
Fuel pressure detecting means for detecting the fuel pressure of the common rail,
Accumulated pressure for controlling the fuel pressure of the common rail by controlling the pressure control valve by the drive signal according to the energization timing based on the fuel pressure detected by the fuel pressure detecting means and the target pressure and a preset energization period. In the fuel injection device,
The pressure response valve responsiveness deterioration amount is calculated based on the energization timing, and the pressure response valve deterioration time amount based on the responsiveness deterioration amount so that a ratio between the pressure control valve response time and the energization period is constant. A pressure-accumulation fuel injection apparatus comprising a correction means for changing the energization period to the control valve longer. The accumulator fuel injection according to claim 6 , wherein the correction unit calculates the responsiveness deterioration amount based on a change in the energization timing for feedback control based on the fuel pressure and the target pressure. apparatus.

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