JP5202722B2 - Control device for accumulator fuel injector - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an accumulator fuel injection device, and more particularly, to control an accumulator fuel injection device including a high pressure pump that pressurizes and pumps low pressure fuel and an electric low pressure pump that supplies the high pressure pump with low pressure fuel. The present invention relates to a control device for an accumulator fuel injection device.

  Conventionally, as a device for supplying fuel to an internal combustion engine such as a diesel engine, a state in which a plurality of fuel injection valves are connected and a common rail for storing high-pressure fuel is provided, and high-pressure fuel is supplied to each fuel injection valve Thus, an accumulator fuel injection device that enables precise fuel injection control by performing energization control of the fuel injection valve is used.

  Such an accumulator fuel injection device is mainly composed of a low pressure pump, a high pressure pump, a common rail, and a fuel injection valve. In this accumulator fuel injection device, the fuel in the fuel tank is transferred to the low pressure pump. And is pressurized by the high-pressure pump and pumped to the common rail, and high-pressure fuel is supplied to each fuel injection valve. In this state, various fuel injection patterns to the internal combustion engine can be realized by controlling the valve opening time and valve opening timing of the fuel injection valve by energization control of the fuel injection valve.

  Here, there is a case where an electric low-pressure pump provided separately from the high-pressure pump is used as the low-pressure pump provided in the pressure accumulation fuel injection device. In this case, the output of the electric low-pressure pump is normally constant, and the excess fuel is overflowed from the overflow valve provided between the electric low-pressure pump and the high-pressure pump pressurization chamber, while flowing to the pressurization chamber of the high-pressure pump. Thus, low pressure fuel is supplied at a necessary flow rate (see, for example, Patent Document 1).

JP 2006-329033 A (FIG. 1)

  In such an accumulator fuel injection device, the electric low-pressure pump pumps low-pressure fuel at a constant cycle. Therefore, the electric low-pressure pump pumps the low-pressure fuel into the low-pressure fuel passage between the electric low-pressure pump and the high-pressure pump. Pressure pulsation occurs. On the other hand, even in the high pressure pump, the cam driving the high pressure pump rotates and the plunger and other parts move to cause pressure pulsation in the high pressure pump, and thus into the low pressure fuel passage that leads the low pressure fuel to the high pressure pump. It may cause pressure pulsation.

These, and n _1-order frequency of the pressure pulsation generated in the low pressure fuel passage due to the driving of the electric low-pressure pump, and the n _2-order frequency of the pressure pulsation generated in the low pressure fuel passage due to the driving of the high pressure pump If approximated, an increase in pressure amplitude or vibration of a low-pressure pipe or a fuel filter provided in the low-pressure fuel passage may cause damage to parts or abnormal noise.

  As a countermeasure against such pressure pulsation resonance, it is possible to provide a damper in the electric low-pressure pump or high-pressure pump, but it is necessary to provide a damper at the location that causes each pressure pulsation. It tends to lead to increase and cost increase.

Accordingly, the inventors of the present invention made extensive efforts, the output of the electric low-pressure pump is variable, the controller of the accumulator fuel injection device, resulting in a high-pressure pump n ₁ primary pumping frequency of the electric low-pressure pump is driven by the high pressure pump It can solve the problems described above by providing a low pressure pump output control unit for controlling the output of the electric low-pressure pump so as not to approximate n ₂ order frequency of the pressure pulsation, in which the present invention has been completed. That is, the present invention relates to a pressure accumulating fuel injection device in which the pressure pulsation generated in the low-pressure fuel passage by the electric low-pressure pump and the pressure pulsation in the low-pressure fuel passage generated by driving the high-pressure pump are resonated. An object is to provide a control device.

According to the present invention, the fuel in the fuel tank is pumped by the electric low-pressure pump, the fuel is pressurized by the high-pressure pump, and pumped to the common rail to which the plurality of fuel injection valves are connected, and the fuel is injected into the cylinder of the internal combustion engine. In a control device for an accumulator type fuel injection device that controls an accumulator type fuel injection device, the pressure pulsation of fuel generated by the driving of the high pressure pump by the n _1st order (n ₁ is an integer of 1 or more) of the electric low pressure pump n ₂ order (n ₂ is an integer of 1 or more) control device for accumulator fuel injection system, characterized in that it comprises a low pressure pump output control unit for controlling the output of the electric low-pressure pump so as not to approximate the frequency is provided, The problems described above can be solved.

  In constructing the pressure accumulation type fuel injection device of the present invention, the low pressure pump output control unit detects the rotational speed of the internal combustion engine or the rotational speed of the high pressure pump, and determines the rotational speed of the internal combustion engine or the rotational speed of the high pressure pump. Accordingly, it is preferable to control the output of the electric low-pressure pump.

  Further, when configuring the accumulator fuel injection device of the present invention, in a region where the output of the electric low-pressure pump is changed by a predetermined amount or more, the low-pressure pump output control unit determines the rotational speed of the internal combustion engine or the high-pressure pump. It is preferable to change the output of the electric low-pressure pump when the amount changes more than a fixed amount.

  In configuring the accumulator fuel injection device of the present invention, it is preferable that the low-pressure pump output control unit controls the output of the electric low-pressure pump in the idling state of the internal combustion engine.

In constituting the accumulator fuel injection device of the present invention, the low-pressure pump output control unit, and a rotation speed detector which detects the rotational speed of the rotational speed or a high-pressure pump of an internal combustion engine, n ₁ primary pumping of the electric low-pressure pump as the frequency is not approximated to n ₂ primary pumping frequency of the high-pressure pump preferably comprises a voltage control unit for controlling the supply voltage to the electric low-pressure pump in accordance with the rotational speed of the internal combustion engine or the high-pressure pump, a.

According to the control apparatus of the accumulator fuel injection device of the present invention, so that the low pressure pump output control unit, n ₁ primary pumping frequency of the electric pump is not approximate to the n _2-order frequency of the pressure pulsation of the fuel caused by the driving of the high-pressure pump In addition, since the output of the electric low-pressure pump is controlled, the risk of resonance between the pressure pulsation generated in the low-pressure fuel passage by the electric low-pressure pump and the pressure pulsation generated in the low-pressure fuel passage by driving the high-pressure pump is reduced. Therefore, the occurrence of problems such as damage to parts constituting the low-pressure fuel passage and abnormal noise is reduced.

In the control device for the accumulator fuel injection device of the present invention, the low-pressure pump output control unit detects the rotational speed of the internal combustion engine or the rotational speed of the high-pressure pump, and outputs the electric low-pressure pump according to any one of the rotational speeds. by controlling the can to pump low pressure fuel from the electric low-pressure pump such that n ₁ primary pumping frequency of n ₂ order frequency and the electric low-pressure pump of the pressure pulsation of the fuel caused by the driving of the high-pressure pump does not approximate.

  Further, in the control device for the accumulator type fuel injection device of the present invention, the low pressure pump output control unit increases the output of the electric low pressure pump by a predetermined amount or more when the rotational speed of the internal combustion engine or the rotational speed of the high pressure pump changes by a predetermined amount or more. By changing, it is possible to avoid repeated significant changes in the output of the electric low-pressure pump in an unstable state in which the rotational speed of the internal combustion engine or the rotational speed of the high-pressure pump is finely increased or decreased.

  Further, in the control device for the accumulator fuel injection device of the present invention, the low pressure pump output control unit performs the above control in the idling state of the internal combustion engine, so that the discharge amount from the high pressure pump is relatively small. Since the output control is performed, there is no possibility that the low-pressure fuel supplied to the high-pressure pump is insufficient. In addition, the low-pressure pump output control unit performs the above-described control in the idling state of the internal combustion engine, so that it is difficult to hear abnormal noise even when the sound generated in the internal combustion engine is relatively low.

Further, in the control device for an accumulator fuel injection device according to the present invention, the low pressure pump output control section includes a predetermined rotation speed detection section and a voltage control section, so that it can respond to the rotation speed of the internal combustion engine or the rotation speed of the high pressure pump. Te, and n ₁ primary pumping frequency of n ₂ primary pumping frequency and an electric low-pressure pump of the high-pressure pump is not to approximate the output of the electric low-pressure pump is controlled.

It is a figure showing an example of composition of an accumulator type fuel injection device provided with a control device of an accumulator type fuel injection device concerning an embodiment of the invention. It is a figure for demonstrating the structural example of the control apparatus of the pressure accumulation type fuel injection apparatus concerning 1st Embodiment. It is a figure for demonstrating the setting method of the supply voltage to the electric low voltage | pressure pump in the control apparatus of the pressure accumulation type fuel injection apparatus concerning 1st Embodiment. It is a figure for demonstrating the time which changes the supply voltage to an electric low pressure pump in steps. It is a flowchart which shows the output control method of the electric low pressure pump by the control apparatus of the pressure accumulation type fuel injection device concerning a 1st embodiment. It is a flowchart which shows the correction method of a supply voltage. It is a figure for demonstrating the setting method of the supply voltage to the electric low voltage | pressure pump in the control apparatus of the pressure accumulation type fuel injection apparatus concerning 2nd Embodiment. It is a figure for demonstrating the setting method of the supply voltage to the electric low pressure pump in the control apparatus of the pressure accumulation type fuel injection apparatus concerning 3rd Embodiment. It is a flowchart which shows the output control method of the electric low pressure pump by the control apparatus of the pressure accumulation type fuel injection apparatus concerning 3rd Embodiment.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments relating to a control device for an accumulator fuel injection device according to the present invention will be specifically described below with reference to the drawings. However, this embodiment shows one aspect of the present invention, and does not limit the present invention, and can be arbitrarily changed within the scope of the present invention. In addition, what attached | subjected the same code | symbol in each figure has shown the same member, and description is abbreviate | omitted suitably.

[First Embodiment]
1. Basic Configuration of Accumulation Type Fuel Injection Device (1) Overall Configuration FIG. 1 shows an accumulation type fuel injection device 50 to be controlled by the control device 40 of the pressure accumulation type fuel injection device according to the first embodiment of the present invention. A schematic configuration is shown.
An accumulator fuel injection device 50 shown in FIG. 1 is an accumulator fuel injector that injects fuel into a cylinder of a diesel engine of a vehicle, and includes a fuel tank 1, an electric low-pressure pump 2, a main filter 4, The high-pressure pump 5, the common rail 10, the fuel injection valve 13 and the like are configured as main elements.

  The electric low-pressure pump 2 and the main filter 4, and the main filter 4 and the high-pressure pump 5 are connected by low-pressure fuel passages 18a and 18b. The high-pressure pump 5 and the common rail 10, and the common rail 10 and the fuel injection valve 13 are high-pressure fuel passages 37a and 37b. Connected with. In addition, fuel leak passages 30 a to 30 c for returning discharged fuel to the fuel tank 1 are connected to the high-pressure pump 5, the common rail 10, the fuel injection valve 13, and the like. In FIG. 1, the high-pressure fuel passages 37a and 37b are indicated by thick lines, the low-pressure fuel passages 18a and 18b and the low-pressure fuel passage 18c in the high-pressure pump 5 are indicated by thin lines, and the fuel leak passages 30a to 30c are indicated by broken lines. Yes.

  A main filter 4 is provided between the low-pressure fuel passages 18a and 18b connecting the electric low-pressure pump 2 and the high-pressure pump 5, and foreign matter in the low-pressure fuel is collected by the main filter 4, and the high-pressure pump Foreign matter does not flow into 5.

(2) Electric Low Pressure Pump The electric low pressure pump 2 sucks up the low pressure fuel in the fuel tank 1 and supplies the low pressure fuel to the pressurizing chamber 5a of the high pressure pump 5 through the low pressure fuel passages 18a to 18c. An electric low-pressure pump 2 shown in FIG. 1 is an in-tank electric low-pressure pump provided in a fuel tank 1 in which low-pressure fuel is stored. The electric low-pressure pump 2 includes an alternator (not shown) and is supplied with a voltage from a battery. The low-pressure fuel having a predetermined flow rate is pumped at an output corresponding to the supply voltage. A pre-filter 3 is interposed in the fuel suction port of the electric low-pressure pump 2, and when the foreign matter is mixed in the fuel in the fuel tank 1, the foreign matter is sucked into the electric low-pressure pump 2. Collect the foreign matter so that it does not.

  However, the low-pressure pump is not limited as long as the rotational speed can be controlled independently of the rotational frequency of the diesel engine and the pumping frequency of the high-pressure pump, and the configuration itself is mechanically driven. Also, it may be configured to be electrically driven.

In the accumulator fuel injection device 50 of FIG. 1, a roller cell type pump is used as the electric low-pressure pump 2 for the in-tank. In the roller cell type pump, the low pressure fuel is pumped by the number of cells during one rotation of the drive shaft. Pressure pulsation is generated in the low pressure fuel passages 18 a to 18 c and also in the main filter 4 by the pumping of the low pressure fuel from the electric low pressure pump 2.
However, the electric low-pressure pump 2 is not limited to the roller cell type pump, and the electric low-pressure pump 2 may be provided outside the fuel tank 1.

(3) High-pressure pump The high-pressure pump 5 is pressure-fed by the electric low-pressure pump 2 and pressurizes the low-pressure fuel introduced into the pressurizing chamber 5a via the fuel intake valve 6 by the plunger 7, and the fuel discharge valve 9 and the high-pressure fuel passage The high pressure fuel is pumped to the common rail 10 via 37a. In the example of the pressure accumulation type fuel injection device 50 shown in FIG. 1, the low pressure fuel sent into the high pressure pump 5 through the low pressure fuel passages 18a and 18b once flows into the cam chamber 16 in which the cam 15 is accommodated. To the pressurizing chamber 5a through the low-pressure fuel passage 18c.

  A flow control valve 8 is provided in the middle of the low pressure fuel passage 18c connecting the cam chamber 16 and the pressurizing chamber 5a, and is supplied to the pressurizing chamber 5a according to the required common rail pressure and the required injection amount. The flow of low pressure fuel is adjusted. As the flow control valve 8, for example, an electromagnetic proportional flow control valve in which the stroke amount of the valve body is variable depending on the magnitude of the supplied pulse voltage is used, and in the low pressure fuel passage 18c as the valve body moves. May cause pulsation.

  Further, on the upstream side of the flow rate control valve 8, there is provided a pressure adjustment valve 14 that is branched and connected from the low pressure fuel flow path 18 c and is arranged in parallel with the flow rate control valve 8. Is further connected to a fuel leak passage 30a leading to the fuel tank 1. The pressure regulating valve 14 is an overflow valve that is opened when the difference between the front and rear pressures, that is, the difference between the pressure in the low-pressure fuel passage 18c and the pressure in the fuel leak passage 30a exceeds a predetermined value. ing. Therefore, in a state where the low-pressure fuel is being pumped by the electric low-pressure pump 2, the pressures in the low-pressure fuel flow paths 18a to 18c and the cam chamber 16 are larger than the pressure in the fuel leak path 30a by a predetermined differential pressure. To be maintained.

A cam 15 that drives the high-pressure pump 5 is fixed to a camshaft connected to a drive shaft of the internal combustion engine via a gear, and the rotational speed of the cam 15 is proportional to the rotational speed of the internal combustion engine.
Further, in the high pressure pump 5 of the pressure accumulating fuel injection device 50 shown in FIG. 1, the two plungers 7 are pushed up by the cams 15, and the low pressure fuel is pressurized in the two pressurizing chambers 5a. High pressure fuel is pumped from 5a to the common rail 10. Therefore, the high pressure fuel is pumped twice from the high pressure pump 5 toward the common rail 10 while the cam 15 rotates once.

  In the high pressure pump 5 configured as described above, the cam 15 rotates, and the plunger 7 moves up and down with the rotation of the cam 15, thereby pulsating the fuel pressure in the high pressure pump 5. That is, the frequency of the pressure pulsation of the fuel generated by driving the high-pressure pump 5 matches the pumping frequency of the fuel by the high-pressure pump 5. This pressure pulsation also affects the pressure of the low-pressure fuel supplied to the high-pressure pump 5 and eventually causes pulsation in the low-pressure fuel passages 18a and 18b.

(4) Common rail The common rail 10 accumulates high-pressure fuel pumped from the high-pressure pump 5 and supplies high-pressure fuel to the plurality of fuel injection valves 13 connected via the high-pressure fuel passage 37b. A rail pressure sensor 21 and a pressure control valve 12 are attached to the common rail 10. For example, an electromagnetic proportional control valve is used as the pressure control valve 12, the amount of fuel leaked from the common rail 10 to the fuel leak passage 30 b is adjusted, and the pressure in the common rail 10 is adjusted according to the amount of leak.

  Further, a rail pressure signal detected by a rail pressure sensor 21 provided in the common rail 10 is sent to the control device 40. The control device 40 controls the pressure control valve 12 provided in the common rail 10 and the flow control valve 8 provided in the high-pressure pump 5 so that the detected rail pressure becomes the target rail pressure.

(5) Fuel Injection Valve The fuel injection valve 13 connected to the common rail 10 includes a nozzle body provided with an injection hole and a nozzle needle that closes the injection hole, and a back pressure acting on the rear end side of the nozzle needle is provided. When the injection hole is opened by the escape, the high-pressure fuel supplied from the common rail 10 is injected into the cylinder of the internal combustion engine. As the fuel injection valve 13, for example, an electromagnetic control type fuel injection valve provided with a solenoid valve as a back pressure control unit, or an electrostrictive type fuel injection valve provided with a piezo element as a back pressure control unit is used.

2. FIG. 2 is a functional block diagram showing a part relating to output control of the electric low-pressure pump 2 in the configuration of the control device 40 of the present embodiment. Yes.
The control device 40 is configured around a microcomputer having a known configuration, and includes a rotation speed determination unit 71, a voltage control unit 73, a voltage correction unit 75, and a switching instruction unit 77. Specifically, each of these units is realized by executing a program by a microcomputer.
The control device 40 may be configured as a part of a control device that controls a flow rate control valve provided in a high-pressure pump, a pressure control valve provided in a common rail, a fuel injection valve of an internal combustion engine, and the like. Alternatively, it may be provided as a control device different from such a control device.

(2) Rotational speed determination unit The rotational speed determination unit 71 reads the rotational speed Ne of the internal combustion engine at a constant period, determines whether the rotational speed Ne is less than a predetermined value Ne0, and the rotational speed Ne is a predetermined value. When it is less than Ne0, the control execution signal S1 is output to the voltage control unit 73. The control device 40 of the present embodiment controls the supply voltage Vfp to the electric low-pressure pump 2 in the idling state of the internal combustion engine when the rotational speed Ne of the internal combustion engine is less than the predetermined value Ne0, while the rotational speed Ne of the internal combustion engine is predetermined. When the value is Ne0 or more, the constant voltage Vfp0 is supplied, and control is performed so that fuel with a constant flow rate is constantly pumped at a constant cycle.

  The control of the supply voltage Vfp of the electric low-pressure pump 2 is performed only when the rotational speed Ne of the internal combustion engine is less than the predetermined value Ne0. The vibration and generation of the internal combustion engine and the high-pressure pump 5 are performed when the internal combustion engine is not in an idle state. Because the operating noise is relatively large, the influence of resonance between the pressure pulsation in the low pressure fuel passages 18a and 18b generated by the electric low pressure pump 2 and the pressure pulsation in the low pressure fuel passages 18a and 18b generated by the high pressure pump 5 is small. is there. Therefore, in the control device 40 of the present embodiment, the load on the control device 40 and the electric low-pressure pump 2 is reduced.

  Note that the rotational speed Np of the high-pressure pump 5 may be used instead of the rotational speed Ne of the internal combustion engine as a determination target in the rotational speed determination unit 71. Since the camshaft that drives the high pressure pump 5 is connected to the drive shaft of the internal combustion engine at a predetermined gear ratio, the threshold Np0 of the rotational speed Np of the high pressure pump 5 corresponding to the threshold Ne0 of the rotational speed Ne of the internal combustion engine. And the rotation speed Np of the high-pressure pump 5 are compared to obtain a similar determination result.

(3) Voltage control unit The voltage control unit 73 adjusts the supply voltage Vfp to the electric low-pressure pump 2 in accordance with the rotational speed Ne of the internal combustion engine. As described above, the control device 40 of the present embodiment performs control to adjust the supply voltage Vfp to the electric low-pressure pump 2 when the rotational speed Ne of the internal combustion engine is less than the predetermined value Ne0, while the rotational speed Ne of the internal combustion engine. Is configured to supply the constant voltage Vfp0 to the electric low-pressure pump 2 when the value is equal to or greater than the predetermined value Ne0.

  The supply voltage Vfp that is controlled when the rotational speed Ne of the internal combustion engine is less than the threshold value Ne0 is set in advance according to the rotational speed Ne of the internal combustion engine. In order to prevent the pressure pulsation generated in the low-pressure fuel passages 18a and 18b by driving the high-pressure pump 5 and the pressure pulsation generated in the low-pressure fuel passages 18a and 18b due to the pumping of the low-pressure fuel from the electric low-pressure pump 2 from resonance. The supply voltage Vfp may be adjusted to be larger than the constant voltage Vfp0 or may be adjusted to be smaller. In the control device 40 of the present embodiment, the supply voltage Vfp to be adjusted is set in consideration of the increase in operating noise of the electric low-pressure pump 2 and the necessity of making the supply voltage Vfp larger than the constant voltage Vfp0. It is set to be smaller than the constant voltage Vfp0.

  In addition, a voltage control unit is used to reliably prevent pressure pulsation resonance by eliminating variations in the pumping frequency under the same supply voltage Vfp due to individual differences in the electric low-pressure pump 2 caused by manufacturing or deterioration over time. The value of the supply voltage Vfp set to 73 is corrected according to the individual difference of the electric low-pressure pump 2 using a correction coefficient K obtained by a voltage correction unit 75 described later.

FIG. 3 is a diagram for explaining an example of a method for setting the supply voltage Vfp to the electric low-pressure pump 2 set in accordance with the rotational speed Ne of the internal combustion engine. The supply voltage Vfp can be greatly changed at one time. An example of when this is not possible is shown. The supply voltage Vfp in FIG. 3 is a set value in the electric low-pressure pump 2 serving as a reference, and is a reference value when the correction coefficient K = 1. The horizontal axis in FIG. 3 represents the rotational speed Ne (rpm) of the internal combustion engine, and the vertical axis represents the frequency (Hz). Also, the broken line in FIG. 3 represents the n ₂ order (n ₂ = 6, 7, 8, 9 in FIG. 3) pumping frequency of the high pressure pump 5 corresponding to the rotational speed Ne of the internal combustion engine, and the dotted line represents the electric low pressure The pumping frequency of the electric low-pressure pump 2 is represented for each supply voltage Vfp to the pump 2. The high-pressure pump 5 of the accumulator fuel injection device 50 of the present embodiment is driven by the rotation of the camshaft connected to the drive shaft of the internal combustion engine at a predetermined gear ratio, so the rotational speed Np of the high-pressure pump 5 and the high-pressure pump 5 n ₂ primary pumping frequency is defined corresponding to the rotation speed Ne of the internal combustion engine.

  In this embodiment, when the supply voltage Vfp to the electric low-pressure pump 2 is not controlled, the supply voltage Vfp is fixed to a constant voltage Vfp0 of 13 V, and the pumping frequency of the low-pressure fuel by the electric low-pressure pump 2 at this time is about 200 Hz. Become. When the constant voltage Vfp0 is supplied to the electric low-pressure pump 2, when the rotational speed Ne of the internal combustion engine is about 750 rpm in the range of the rotational speed Ne shown in FIG. When the frequency and the 25th-order pumping frequency of the electric low-pressure pump 2 coincide (illustrated by a black dot P1) and the rotational speed Ne of the internal combustion engine is about 860 rpm, the seventh-order pumping frequency of the high-pressure pump 5 and the electric low-pressure pump 2 The 29th pumping frequency approximates (illustrated by a black dot P2).

In addition, in FIG. 3, the supply voltage Vfp is 10V to the electric low-pressure pump 2, 11V, 12V, in the case of 14 V, n ₂ primary pumping frequency and n ₁ primary pumping frequency of the electric low-pressure pump 2 in the high-pressure pump 5 The points that are approximated by are also indicated by black dots.
That is, in FIG. 3, the broken lines representing the n _2-order pumping frequency of the high-pressure pump 5, a point which intersects the dashed line representing the pumping frequency of the electric low-pressure pump 2 occurs at low pressure fuel passage 18a, 18b and the main filter within 4 Resonance point of pressure pulsation. At this time, the vibrations of the low-pressure fuel passages 18a and 18b and the main filter 4 are likely to increase or abnormal noise is likely to occur.

  Therefore, in the control device 40 of the present embodiment, the supply voltage Vfp to the electric low-pressure pump 2 is set according to the rotational speed Ne of the internal combustion engine so as not to overlap these resonance points. The solid line in FIG. 3 indicates the set value of the supply voltage Vfp to the electric low-pressure pump 2 so that it does not overlap with a plurality of resonance points and the number of points at which the supply voltage Vfp changes step by step is minimized. A supply voltage Vfp corresponding to the rotational speed Ne of the internal combustion engine is set.

Specifically, in the operating range where the rotational speed Ne of the internal combustion engine is less than 800 rpm, the rotation of the internal combustion engine changes so as to transit between the 7th pumping frequency line and the 8th pumping frequency line of the high-pressure pump 5. As the number Ne increases, the supply voltage Vfp to the electric low-pressure pump 2 changes proportionally between 12V and 13V. The supply voltage Vfp in this operation region is set based on the following formula (1).
Vfp = a · Ne + b (1)

Further, when the supply voltage Vfp to the electric low-pressure pump 2 becomes 13V, the supply voltage Vfp exceeds the constant voltage Vfp0 and the operation sound of the electric low-pressure pump 2 starts to increase, so the supply voltage Vfp to the electric low-pressure pump 2 is 13V. The supply voltage Vfp is lowered to 12V at the point where the rotational speed Ne of the internal combustion engine becomes 800 rpm. In the operating region where the rotational speed Ne of the internal combustion engine is 800 rpm or more, the rotational speed Ne of the internal combustion engine is changed between the sixth pumping frequency line and the seventh pumping frequency line of the high-pressure pump 5. As the voltage increases, the supply voltage Vfp to the electric low-pressure pump 2 changes proportionally between 12V and 13V. The supply voltage Vfp in this operation region is set based on the following formula (2).
Vfp = α (a · Ne + b) (2)

  That is, in the operating region where the rotational speed Ne of the internal combustion engine is 800 rpm or higher, the value obtained by the equation (1) of the supply voltage Vfp in the operating region where the rotational speed Ne is less than 800 rpm is multiplied by the coefficient α. The voltage Vfp is set.

  Then, when the rotational speed Ne of the internal combustion engine at which the supply voltage Vfp to the electric low-pressure pump 2 is 13 V is 920 rpm, the vibration of the internal combustion engine and the high-pressure pump 5 and the generated operating noise begin to become relatively large. In the operation region where the engine speed Ne is 920 rpm or more, the supply voltage Vfp to the electric low-pressure pump 2 is fixed to the constant voltage Vfp0. That is, in the example of FIG. 3, the threshold value Ne0 of the internal combustion engine speed Ne when the rotational speed determination unit 71 determines whether or not the control of the supply voltage Vfp of the electric low-pressure pump 2 is executed is the idle state of the internal combustion engine. It is set to 920 rpm which becomes a state close to.

  Note that the set value of the supply voltage Vfp shown by the solid line in FIG. 3 is merely an example, and various settings are possible as long as the supply voltage Vfp does not overlap the resonance point. Further, the threshold value Ne0 of the internal combustion engine speed Ne for identifying whether or not the control of the supply voltage Vfp of the electric low-pressure pump 2 is executed can also be set to a desired speed, or the threshold value Ne0 is not provided. In addition, the supply voltage Vfp of the electric low-pressure pump 2 may be controlled over the entire rotation speed Ne of the internal combustion engine.

(4) Voltage correction unit The electric low-pressure pump 2 may vary in pump rotation speed even if the same voltage is supplied due to individual differences. When the variation in the pump rotation speed occurs, the actual pumping frequency by the electric low-pressure pump 2 is assumed even when the supply voltage Vfp preset in the voltage control unit 73 is supplied to the electric low-pressure pump 2. It may deviate from the pumping frequency. As a result, in spite of the adjustment of the supply voltage Vfp to the electric low-pressure pump 2, and n ₁ primary pumping frequency of n ₂ order frequency and the electric low-pressure pump 2 rotation speed of the high-pressure pump 5 will approximate, There is a possibility that resonance in the low-pressure fuel passages 18a and 18b and the main filter 4 is not reduced.

Therefore, the control device 40 of the present embodiment is configured so that the number of rotations of the pump depends on the individual difference between the electric low-pressure pump that is used as a reference when setting the supply voltage Vfp in the voltage controller 73 and the electric low-pressure pump 2 that is actually used. taking into account the variation in, provided with a voltage correction unit 75 so that control not to approximate the n _1-order pumping frequency of n ₂ primary pumping frequency and the electric low-pressure pump 2 in the high-pressure pump 5 is ensured Yes.

  The voltage correction unit 75 of the control device 40 according to the present embodiment detects a current value Afp that is supplied to the electric low-pressure pump 2 in an operation region in which the supply voltage Vfp to the electric low-pressure pump 2 is set to the constant voltage Vfp0. Then, the rotational speed Nfp of the electric low-pressure pump 2 is obtained based on the current value Afp. Further, the voltage correction unit 75 obtains the pumping frequency Ffp from the electric low-pressure pump 2 based on the obtained rotation speed Nfp, and compares it with the pumping frequency Ffp0 at the constant voltage Vfp0 stored in the voltage control unit 73. Thus, the deviation ΔFfp from the set pumping frequency Ffp0 is obtained.

Then, a supply voltage Vfp ′ at which the pumping frequency Ffp is Ffp0 in the actually used electric low-pressure pump 2 is calculated from the determined pumping frequency deviation ΔFfp to obtain a correction coefficient K = Vfp ′ / Vfp. When the correction coefficient K is obtained, the voltage correction unit 75 outputs the correction coefficient K to the voltage control unit 73.
As a result, the voltage control unit 73 multiplies the supply voltage value set in advance according to the rotational speed Ne of the internal combustion engine by the correction coefficient K to update the set value of the supply voltage Vfp.

The time when the voltage correction unit 75 obtains the correction coefficient K may not be the time when the constant voltage Vfp0 is supplied to the electric low-pressure pump 2. However, when the constant voltage Vfp0 is being supplied to the electric low-pressure pump 2, the electric low-pressure pump 2 is in a state of pumping low-pressure fuel at a constant pumping cycle. Easy to find accurately.
In addition, the voltage correction unit 75 of the control device 40 of the present embodiment obtains the correction coefficient K based on the deviation ΔFfp of the pumping frequency. In addition to this, the electric low-pressure pump 2 to be used is driven at a predetermined rotational speed. The correction voltage K is calculated by comparing the supply voltage required for the above with the supply voltage preset in the voltage controller 73, calculating the deviation of the supply voltage required to obtain the same rotation speed. Also good.

(5) Switching instruction unit In the control device 40 of the present embodiment, when the voltage control unit 73 controls the supply voltage Vfp to the electric low-pressure pump 2, a region in which the preset supply voltage Vfp is changed by a predetermined amount or more. The switching instruction unit 77 that instructs the voltage control unit 73 to switch the calculation formula so that the supply voltage Vfp is changed only when the change amount ΔNe of the rotational speed Ne of the internal combustion engine changes by a predetermined amount or more. Is provided.

  In the example shown in FIG. 3 described above, the calculation formula of the supply voltage Vfp is switched between Formula (1) and Formula (2) when the rotational speed Ne of the internal combustion engine is about 800 rpm, and the supply voltage Vfp is 13V and 12V. The setting changes step by step. Therefore, for example, in the idling state of the internal combustion engine, when the rotational speed Ne of the internal combustion engine becomes unstable and finely increases or decreases around 800 rpm, the supply voltage Vfp to the electric low-pressure pump 2 is repeatedly switched between 13V and 12V. . As described above, when the output of the electric low-pressure pump 2 is finely switched, there is a possibility that a follow-up delay occurs in the control. Further, since the flow rate of the low-pressure fuel pumped to the high-pressure pump 5 changes repeatedly, the pressure control at the inlet of the flow control valve 8 depends on the responsiveness of the pressure adjustment valve 14 that adjusts the pressure of the low-pressure fuel in the low-pressure fuel passage. May become impossible, and the rail pressure may not be accurately controlled.

  For this reason, the control device 40 of the present embodiment allows the supply voltage Vfp to the electric low-pressure pump 2 to be from 13V to 12V, even in an unstable state where the rotational speed Ne of the internal combustion engine increases or decreases finely around 800 rpm. It is configured not to be switched from 12V to 13V. Specifically, the calculation formula is changed from Formula (1) to Formula (2) depending on whether the calculation formula that is the reference for the set value of the current supply voltage Vfp is based on Formula (1) or Formula (2). Alternatively, the threshold value of the rotational speed Ne for switching from the expression (2) to the expression (1) is varied.

  For example, when the voltage control unit 73 currently sets the supply voltage Vfp on the basis of the expression (1), the switching instruction unit 77 displays the first switching threshold value Ne1 when the internal combustion engine speed Ne is around 800 rpm. If it is less, the calculation formula instruction signal S2 is output to the voltage control unit 73 so that the supply voltage Vfp is set with reference to the formula (1) without switching the calculation formula. On the other hand, when the supply voltage Vfp is set with reference to the formula (1), the switching instruction unit 77 calculates the formula from the formula (1) when the rotational speed Ne of the internal combustion engine becomes equal to or higher than the first switching threshold value Ne1. The calculation formula instruction signal S2 is output to the voltage control unit 73 so as to set the supply voltage Vfp with reference to the formula (2).

  Further, when the supply voltage Vfp is currently set in the voltage control unit 73 with reference to the expression (2), the switching instruction unit 77 indicates that the rotational speed Ne of the internal combustion engine is smaller than the first switching threshold value Ne1. When the value exceeds the second switching threshold value Ne2, the calculation formula instruction signal S2 is output to the voltage control unit 73 so that the supply voltage Vfp is set with reference to the formula (2) without switching the calculation formula. On the other hand, when the supply voltage Vfp is set on the basis of the formula (2), the switching instruction unit 77 calculates the formula from the formula (2) when the rotational speed Ne of the internal combustion engine becomes equal to or less than the second switching threshold value Ne2. The calculation formula instruction signal S2 is output to the voltage controller 73 so as to set the supply voltage Vfp based on the formula (1).

  As a result of adjusting the switching timing of the calculation formula by the switching instruction unit 77, when the rotational speed Ne of the internal combustion engine changes from less than 800 rpm to approximately 800 rpm or more, as shown in FIG. When the rotation speed Ne is 805 rpm, which is the first switching threshold value Ne1, the supply voltage Vfp to the electric low-pressure pump 2 is step-changed from 13V to 12V. When the rotational speed Ne of the internal combustion engine changes from approximately 800 rpm to less than 800 rpm, as shown in FIG. 4 (b), the motor is operated when the rotational speed Ne of the internal combustion engine is 795 rpm, which is the second switching threshold value Ne2. The supply voltage Vfp to the low pressure pump 2 is step-changed from 12V to 13V.

  Therefore, when the rotational speed Ne of the internal combustion engine is around 800 rpm, the supply voltage Vfp to the electric low-pressure pump 2 does not change stepwise unless the rotational speed Ne of the internal combustion engine changes by at least 10 rpm. Therefore, the supply voltage Vfp is not repeatedly switched between 12V and 13V.

3. Output Control Method for Electric Low Pressure Pump Next, an output control method for the electric low pressure pump 2 performed by the control device 40 of the accumulator fuel injection device of the present embodiment shown in FIG. 2 is based on the flow of FIGS. 5 and 6. explain.
In the example of the output control flow, first, in step S1 of FIG. 5, the voltage correction unit 75 sets the value of the supply voltage Vfp preset in the voltage control unit 73 according to the rotational speed Ne of the internal combustion engine to the electric low voltage. Correction is made according to individual differences of the pump 2.

  FIG. 6 is a flowchart specifically showing step S <b> 1. First, in step S <b> 51, the voltage control unit 73 outputs an instruction to the alternator so as to supply the constant voltage Vfp <b> 0 to the electric low-pressure pump 2. Next, in step S52, the voltage correction unit 75 detects the current value Afp that is energized to the electric low-pressure pump 2, and then in step S53, the rotational speed Nfp and the pressure feed of the electric low-pressure pump 2 corresponding to the current value Afp. Calculate the frequency Ffp.

Next, in step S54, the voltage correction unit 75 obtains a deviation ΔFfp between the obtained pumping frequency Ffp and the pumping frequency Ffp0 when the constant voltage Vfp0 preset in the voltage control unit 73 is supplied, and then in step S55. The supply voltage Vfp ′ at which the pumping frequency Ffp becomes Ffp0 in the electric low-pressure pump 2 being used is calculated.
In step S56, the voltage correction unit 75 calculates the correction coefficient K = Vfp ′ / Vfp and outputs the correction coefficient K to the voltage control unit 73. In step S57, the voltage control unit 73 is set in advance. The correction of the supply voltage Vfp in step S1 is completed by multiplying the value of the supplied voltage Vfp by the correction coefficient K and updating the set value of the supply voltage Vfp.

  Returning to FIG. 5, next, in step S <b> 2, the rotational speed determination unit 71 detects the rotational speed Ne of the internal combustion engine. Next, in step S3, the rotation speed determination unit 71 determines whether or not the detected rotation speed Ne is less than a predetermined value Ne0. If the rotational speed Ne is equal to or greater than the predetermined value Ne0, vibrations of the low-pressure fuel passages 18a and 18b and the main filter 4, operating noise of the internal combustion engine, and the like are relatively loud, so the supply voltage Vfp to the electric low-pressure pump 2 needs to be adjusted. Since the performance is low, the process proceeds to step S12, the voltage control unit 73 sets the supply voltage Vfp to the constant voltage Vfp0, outputs a control signal to the alternator of the electric low-pressure pump 2, and then returns to step S1.

  On the other hand, if the rotational speed Ne of the internal combustion engine is less than the predetermined value Ne0, the process proceeds to step S4, and the calculation formula serving as a reference for the switching instruction unit 77 to set the current supply voltage Vfp to the electric low-pressure pump 2 is the above formula. It is determined whether or not (1). When the current supply voltage Vfp is set on the basis of the formula (1), that is, when the rotation speed Ne of the internal combustion engine up to the previous time is approximately less than 800 rpm, the process proceeds to step S5, where the switching instruction unit 77 It is determined whether or not the rotational speed Ne of the internal combustion engine is equal to or higher than 805 rpm, which is the first switching threshold value Ne1.

  When the rotational speed Ne of the internal combustion engine is less than the first switching threshold value Ne1, the process proceeds to step S6, and the switching instruction unit 77 directly supplies the voltage Vfp to the voltage control unit 73 based on the formula (1). An instruction is output to continue setting. On the other hand, when the rotational speed Ne of the internal combustion engine is equal to or greater than the first switching threshold value Ne1, the process proceeds to step S7, and the switching instruction unit 77 serves as a reference for setting the supply voltage Vfp to the voltage control unit 73. The calculation formula is switched from formula (1) to formula (2), and an instruction is output to set the supply voltage Vfp based on formula (2).

  In step S4, the calculation formula as a reference for setting the current supply voltage Vfp to the electric low-pressure pump 2 is not the above formula (1), that is, the rotation speed Ne of the internal combustion engine up to the previous time is approximately 800 rpm or more and is calculated. When it is determined that the expression (2) is used as an expression, the process proceeds to step S8, and the switching instruction unit 77 determines whether or not the rotational speed Ne of the internal combustion engine is equal to or less than 795 rpm, which is the second switching threshold value Ne2. Is determined.

  When the rotational speed Ne of the internal combustion engine exceeds the second switching threshold value Ne2, the process proceeds to step S9, and the switching instruction unit 77 supplies the voltage control unit 73 as it is based on the formula (2). An instruction is output to continue setting the voltage Vfp. On the other hand, when the rotational speed Ne of the internal combustion engine is equal to or less than the second switching threshold value Ne2, the process proceeds to step S10, and the switching instruction unit 77 serves as a reference for setting the supply voltage Vfp to the voltage control unit 73. The calculation formula is switched from formula (2) to formula (1), and an instruction is output to set the supply voltage Vfp based on formula (1).

  In step S6, S7, S9, or S10, after the voltage control unit 73 receives an instruction of a calculation formula serving as a reference for setting the supply voltage Vfp, in step S11, the voltage control unit 73 determines the rotational speed Ne of the internal combustion engine. The supply voltage Vfp to the electric low-pressure pump 2 defined according to is set, a control signal is output to the alternator of the electric low-pressure pump 2, and the process returns to step S1.

According to the output control method of the electric low-pressure pump 2 is performed as above, in the rotational speed Ne is relatively low idling state of the internal combustion engine, n ₁ primary pumping frequency of the electric low-pressure pump 2 is driven by the high pressure pump 5 it is avoided that approximates n ₂ order frequency of the pressure pulsation of the resulting fuel. Therefore, in the low pressure fuel passage and the main filter, the damage of these components and the generation of abnormal noise due to the resonance of the pressure pulsation caused by the electric low pressure pump 2 and the pressure pulsation caused by the high pressure pump 5 are reduced.

Further, in the output control method of the electric low-pressure pump 2 described in the present embodiment, variations in the pumping frequency Ffp under the same supply voltage Vfp due to individual differences of the electric low-pressure pump 2 caused by manufacturing or deterioration with time. There to be eliminated, is reliably avoided that n ₁ primary pumping frequency of the electric low-pressure pump 2 is approximated to n _2-order frequency of the pressure pulsation of the fuel caused by the driving of the high-pressure pump 5.

  Furthermore, in the output control method for the electric low-pressure pump 2 described in the present embodiment, the supply voltage Vfp is not repeatedly switched in a region where the supply voltage Vfp to the electric low-pressure pump 2 changes stepwise. It is also possible to prevent the following delay and the rail pressure control from being disabled.

[Second Embodiment]
Control device for accumulator fuel injection system according to a second embodiment of the present invention, the approximation n ₁ primary pumping frequency of the electric low-pressure pump 2 and n _2-order frequency of the pressure pulsation of the fuel caused by the driving of the high pressure pump 5 In addition to controlling the output of the electric low-pressure pump 2 so as not to cause a failure, the output of the electric low-pressure pump 2 is controlled so that the pumping frequency of the electric low-pressure pump 2 does not approximate the frequency of the reciprocating motion of the valve body of the flow control valve 8. Is configured to do.

  FIG. 7 is a diagram for explaining a setting example of the supply voltage Vfp to the electric low-pressure pump 2 set in the voltage control unit of the control device of the present embodiment. Broken lines and dotted lines represent the same contents as in FIG. In FIG. 7, the frequency (about 185 Hz) of the reciprocating motion of the valve body of the flow control valve 8 is further indicated by a one-dot chain line.

  In the control device of the present embodiment, basically, in the operation region where the rotational speed Ne of the internal combustion engine is less than a predetermined value Ne0 (= 920 rpm), the sixth pumping frequency line and the seventh pumping frequency line of the high-pressure pump 5 are basically. The supply voltage Vfp to the electric low-pressure pump 2 changes proportionally as Ne of the internal combustion engine increases so as to change between the lines.

  However, when the supply voltage Vfp to the electric low-pressure pump 2 is about 12.3 V, the pumping frequency of the electric low-pressure pump 2 and the frequency of the reciprocating motion of the valve body of the flow control valve 8 are approximated. The supply voltage Vfp to the low pressure pump 2 is not set between 12V and 12.6V. That is, in the operating region where the rotational speed Ne of the internal combustion engine is between 820 rpm and 890 rpm, the rotational speed Ne of the internal combustion engine increases when the set value of the supply voltage Vfp is below the sixth pumping frequency line of the high-pressure pump 5. As it is done, it is switched so as to change proportionally.

If the supply voltage Vfp to the electric low-pressure pump 2 is set as shown in FIG. 7, the pressure pulsation caused by the electric low-pressure pump 2 and the pressure pulsation caused by the flow control valve 8 are reduced to the low-pressure fuel passages 18a, 18b, Resonance in the main filter 4 is also avoided, and damage and abnormal noise of the low-pressure fuel passages 18a and 18b and the main filter 4 are further reduced.
Also in the control device of the present embodiment, the rotational speed Ne of the internal combustion engine is unstable in the operating region where the rotational speed Ne of the internal combustion engine changes around 820 rpm and 890 rpm where the supply voltage Vfp to the electric low-pressure pump 2 changes stepwise. Thus, the supply voltage Vfp can be prevented from being repeatedly switched.

[Third Embodiment]
The control device of the accumulator fuel injection device according to the first and second embodiments described above is configured when the supply voltage Vfp to the electric low-pressure pump 2 cannot be changed greatly at a time. On the other hand, the control device for an accumulator fuel injection apparatus according to the third embodiment of the present invention includes an electric low pressure in the case where the accumulator fuel injection apparatus is provided with a voltage variable to be supplied to the electric low pressure pump 2. This configuration is applicable when the supply voltage Vfp to the pump 2 can be greatly changed at once.

1. Control device for accumulator fuel injection device (1) Rotational speed determination unit and voltage correction unit The rotational speed determination unit and voltage correction unit provided in the control device of this embodiment are the same as those of the control device of the first embodiment. It is configured.

(2) Voltage Control Unit The voltage control unit provided in the control device of the present embodiment changes the supply voltage Vfp to the electric low-pressure pump 2 according to the rotational speed Ne of the internal combustion engine to a first constant voltage Vfp1 (first And the second constant voltage Vfp2 are controlled to be switched. Specifically, the control device sets the supply voltage Vfp to the electric low-pressure pump 2 to the second constant voltage Vfp2 when the rotational speed Ne of the internal combustion engine is less than a predetermined value Ne0, while the rotational speed Ne of the internal combustion engine. Is equal to or greater than a predetermined value Ne0, the supply voltage Vfp to the electric low-pressure pump 2 is set to the first constant voltage Vfp1.

The second constant voltage Vfp2 is a range in which the rotational speed Ne of the internal combustion engine is lower than a predetermined value Ne0 that is close to the idle state of the internal combustion engine and is greater than or equal to the rotational speed Ne that can be assumed in the idle state of the internal combustion engine. in inner, a value so that the resonance point of the n ₂ primary pumping frequency and n ₁ primary pumping frequency of the electric low-pressure pump 2 in the high-pressure pump 5 does not exist is set.
However, the second constant voltage Vfp2 is set so that the supply amount of the low-pressure fuel to the high-pressure pump 5 is not short.

FIG. 8 is a diagram for explaining a method of setting the supply voltage Vfp to the electric low-pressure pump 2 set in accordance with the rotational speed Ne of the internal combustion engine. The horizontal and vertical axes, the broken line and the dotted line in FIG. Represents the same contents as FIG.
In the setting example of the supply voltage Vfp of the present embodiment shown in FIG. 8, in the region where the rotational speed Ne of the internal combustion engine is 920 rpm or more, the supply voltage Vfp to the electric low-pressure pump 2 is 13V, which is the first constant voltage Vfp1. On the other hand, in the operating region where the rotational speed Ne of the internal combustion engine is less than 920 rpm, the supply voltage Vfp is fixed to 10 V, which is the second constant voltage Vfp2. Therefore, the rotation speed Ne of the internal combustion engine and n ₁ primary pumping frequency of n ₂ primary pumping frequency and the electric low-pressure pump 2 in the high-pressure pump 5 is in the operating area of less than 920rpm there is no fear of approximation.

Even when the supply voltage Vfp to the electric low-pressure pump 2 is reduced to 10 V when the rotational speed Ne of the internal combustion engine is less than 920 rpm, as in the example of the control device of the present embodiment, the internal combustion engine is in a state close to the idle state Therefore, since the pumping amount from the high-pressure pump 5 to the common rail 10 is relatively small, the supply amount of the low-pressure fuel to the pressurizing chamber 5a of the high-pressure pump 5 is not short and can be realized.
The set value of the second constant voltage Vfp2 is not limited to 10V, but should be set in consideration of the ability of the supply voltage variable, the amount of low-pressure fuel supplied to the pressurizing chamber 5a of the high-pressure pump 5, and the like. Is preferred.

  In the control device of this embodiment, the pressure pulsation resonance is reliably eliminated by eliminating variations in the pumping frequency under the same supply voltage Vfp due to individual differences in the electric low-pressure pump 2 caused by manufacturing or deterioration over time. Therefore, the value of the supply voltage Vfp set in the voltage control unit 73 is corrected according to the individual difference of the electric low-pressure pump 2 by using the correction coefficient K obtained by the voltage correction unit 75. It has become.

(3) Switching instruction unit The switching instruction unit provided in the control device of the present embodiment basically has the same function as the switching instruction unit provided in the control device of the first embodiment. Yes. However, the switching instruction unit of the control device according to the first embodiment is configured so that the rotation speed of the internal combustion engine is in the operating range where the supply voltage Vfp to the electric low-pressure pump 2 changes stepwise and the rotation speed Ne of the internal combustion engine is around 800 rpm. Although the supply voltage Vfp is not repeatedly switched due to Ne becoming unstable, the switching instruction unit of the control device of the present embodiment is configured such that the supply voltage Vfp is equal to the first constant voltage Vfp1 and the second constant voltage Vfp1. In the operating region where the rotational speed Ne of the internal combustion engine is switched to the constant voltage Vfp2, the rotational speed Ne of the internal combustion engine becomes unstable and the supply voltage Vfp is not repeatedly switched. .

2. Output Control Method for Electric Low Pressure Pump Next, an output control method for the electric low pressure pump 2 performed by the control device 40 of the accumulator fuel injection device of this embodiment will be described based on the flow of FIG.
In this example of the output control flow, first, in step S21, similarly to step S1 of the output control flow of the first embodiment, the supply voltage preset in the voltage control unit in accordance with the rotational speed Ne of the internal combustion engine. Correct the Vfp value.

  Next, after the rotational speed determination unit detects the rotational speed Ne of the internal combustion engine in step S22, in step S23, the switching instruction unit sets the current supply voltage Vfp to the electric low-pressure pump 2 to the first constant voltage Vfp1. It is determined whether or not. When the current supply voltage Vfp is set to the first constant voltage Vfp1, the process proceeds to step 24, where the switching instruction unit determines that the rotational speed Ne of the internal combustion engine detected at step S22 is the second switching threshold value Ne2. It is determined whether or not it is a certain 915 rpm or less.

  When the rotational speed Ne of the internal combustion engine exceeds the second switching threshold value Ne2, the process proceeds to step S25, where the switching instruction unit supplies the supply voltage Vfp to the first constant voltage Vfp1 to the voltage control unit. An instruction is output to keep it as it is. On the other hand, when the rotational speed Ne of the internal combustion engine is equal to or smaller than the second switching threshold value Ne2, the process proceeds to step S26, and the switching instruction unit sends the supply voltage Vfp to the second constant voltage Vfp2 to the voltage control unit. An instruction to switch to is output.

  In step S23, if the current setting of the supply voltage Vfp to the electric low-pressure pump 2 is not the first constant voltage Vfp1, that is, the second constant voltage Vfp2, the process proceeds to step S27, where the switching instruction unit It is determined whether or not the rotational speed Ne of the internal combustion engine detected in step S22 is not less than 925 rpm which is the first switching threshold value Ne1.

  When the rotational speed Ne of the internal combustion engine is less than the first switching threshold value Ne1, the process proceeds to step S28, and the switching instruction unit keeps the supply voltage Vfp as the second constant voltage Vfp2 with respect to the voltage control unit. Output instructions to maintain. On the other hand, when the rotational speed Ne of the internal combustion engine is equal to or greater than the first switching threshold value Ne1, the process proceeds to step S29, where the switching instruction unit sends the supply voltage Vfp to the first constant voltage Vfp1 to the voltage control unit. An instruction to switch to is output.

  In step S25, S26, S28 or S29, after the voltage control unit receives an instruction of the supply voltage Vfp, in step S30, the voltage control unit outputs a control signal to the alternator of the electric low-pressure pump 2, Return to step S21.

Also in the output control method of the electric low-pressure pump 2 of the present embodiment is performed as above, in the rotational speed Ne is relatively low idling state of the internal combustion engine, n ₁ primary pumping frequency high-pressure pump 5 of the electric low-pressure pump 2 Approximation to the n _second order frequency of the fuel pressure pulsation caused by the driving of is avoided. Therefore, in the low pressure fuel passage and the main filter, the damage of these components and the generation of abnormal noise due to the resonance of the pressure pulsation caused by the electric low pressure pump 2 and the pressure pulsation caused by the high pressure pump 5 are reduced.

Further, in the output control method of the electric low-pressure pump 2 described in the present embodiment, variations in the pumping frequency Ffp under the same supply voltage Vfp due to individual differences of the electric low-pressure pump 2 caused by manufacturing or deterioration with time. There to be eliminated, is reliably avoided that n ₁ primary pumping frequency of the electric low-pressure pump 2 is approximated to n _2-order frequency of the pressure pulsation of the fuel caused by the driving of the high-pressure pump 5.

  Further, in the output control method of the electric low-pressure pump 2 described in the present embodiment, the supply voltage Vfp is not repeatedly switched in a region where the supply voltage Vfp to the electric low-pressure pump 2 changes stepwise. It is also possible to prevent the following delay and the rail pressure control from being disabled.

Claims (5)

An accumulator fuel that pumps fuel in a fuel tank with an electric low-pressure pump, pressurizes the fuel with a high-pressure pump, pumps the fuel into a common rail connected to a plurality of fuel injection valves, and injects the fuel into a cylinder of an internal combustion engine In a control device for an accumulator fuel injection device that controls an injection device,
The n _1st order (n ₁ is an integer greater than or equal to ₁ ) pumping frequency of the electric low-pressure pump does not approximate the n _2nd order (n ₂ is an integer greater than or equal to 1) frequency of the fuel pressure pulsation caused by driving the high pressure pump. And a low-pressure pump output control unit for controlling the output of the electric low-pressure pump.   The low-pressure pump output control unit detects the rotational speed of the internal combustion engine or the rotational speed of the high-pressure pump, and controls the output of the electric low-pressure pump according to the rotational speed of the internal combustion engine or the rotational speed of the high-pressure pump. The control device for a pressure-accumulation fuel injection device according to claim 1.   In a region where the output of the electric low-pressure pump is changed by a predetermined amount or more, the low-pressure pump output control unit controls the electric low-pressure pump when the rotation speed of the internal combustion engine or the rotation speed of the high-pressure pump changes by a predetermined amount or more. The control device for an accumulator fuel injection device according to claim 2, wherein the output is changed.   The said low-pressure pump output control part controls the output of the said electric low-pressure pump in the idle state of the said internal combustion engine, The control apparatus of the pressure accumulation type fuel-injection apparatus as described in any one of Claims 1-3 characterized by the above-mentioned. . The low-pressure pump output control unit is
A rotational speed detector for detecting the rotational speed of the internal combustion engine or the rotational speed of the high-pressure pump;
As the n ₁ primary pumping frequency of the electric low-pressure pump is not approximated to n ₂ primary pumping frequency of the high-pressure pump, to control the voltage supplied to the electric low-pressure pump in accordance with the rotational speed of the internal combustion engine or the high-pressure pump A voltage controller;
The control apparatus for an accumulator fuel injection device according to claim 1, comprising:

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