JP2018096351A - Engine supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve filling efficiency of intake air with a simple configuration.SOLUTION: An engine supercharger 10 includes an intake passage 26 connected with an engine 14, an electric compressor 32 provided in the intake passage 26 and driven by a motor 34 so as to compress intake air flowing through the intake passage 26, and a controller 40 for periodically varying rotational speed of the electric compressor 32 so that a peak of intake pulsation in an intake port occurs between the period from the maximum lift to the closing of an intake valve with using rotational speed and a crank angle of the engine 14 as input.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine supercharger.

  Conventionally, for example, the intake pipe is composed of a fixed intake pipe and a movable intake pipe in order to improve the volume efficiency of the engine by utilizing the pulsation effect and the inertia effect caused by the pressure wave generated in the intake pipe in the intake stroke of the internal combustion engine. Then, a variable length intake pipe is provided on the intake side of the carburetor so that the length of the intake pipe can be increased or decreased by bringing the movable intake pipe into and out of contact with the fixed intake pipe according to the rotational speed of the internal combustion engine. A known internal combustion engine is known (Patent Document 1).

  In addition, in an internal combustion engine such as an engine, an intake control valve provided in an intake passage downstream of a surge tank is known (see, for example, Patent Documents 2 to 4). According to such a control device, it is possible to obtain an inertia supercharging effect by opening the intake control valve after the intake valve downstream of the intake port is opened.

  In addition, there is known control that performs inertia supercharging by intermittently applying a drive current (Patent Document 5). This control is intermittent drive control that increases the drive current of the electric supercharger when the crank angle range corresponding to the valve opening period of the intake valve of the engine is present. In addition, a small current that does not stop the electric supercharger flows outside the crank angle range.

JP-A-61-49124 JP 2005-171941 A Japanese Patent Laid-Open No. 3-26825 JP 2006-283633 A JP 2005-188487 A

  Conventionally, a technique for improving the volume efficiency of an engine by using a pulsation effect and an inertia effect by a pressure wave is known.

  Further, in this pulsation effect and inertia effect, the optimum pressure wave differs depending on the engine speed and load, so the intake pipe length is changed or a control valve is provided. However, the provision of a new mechanism for changing the intake pipe length in a limited engine room or the provision of a control valve is a problem of increasing the size due to an increase in weight and an increase in overall volume. In addition, the complicated intake passage not only lowers the output of the internal combustion engine due to intake pressure loss, but also increases the cost.

  On the other hand, the pressure wave pulsation differs from the optimum pressure wave depending on the engine speed and load.Therefore, if not controlled properly, the pressure will be reduced during the intake stroke depending on the engine speed. There is a problem of reducing volumetric efficiency.

  Further, since the electric compressor can be controlled with high response regardless of the state of exhaust, control for operating the motor of the supercharger at an arbitrary rotational speed with respect to the rotational speed of the engine is known. On the other hand, since the electric compressor uses electric power from the battery, the output is limited, and it is a problem that only limited supercharging work can be performed. Therefore, it is an object to improve the volume efficiency of the engine as much as possible within the limit of the output.

  Further, when the supercharger is operated at a certain rotational speed with respect to the engine speed, pressure wave pulsation due to suction force of the intake stroke occurs. Therefore, there is a problem that the volumetric efficiency is reduced depending on the engine speed as described above.

  In the technique described in Patent Document 5, there has been an attempt to perform inertia supercharging by intermittently applying a drive current to the electric compressor. However, even if the current is applied intermittently, the compressor impeller, shaft, and motor mover are subject to rotational inertia, so the compressor speed hardly changes and the desired inertial supercharging is generated. It is difficult. In particular, under the operating conditions where the engine speed is high, since the time interval of the intermittent current is short, the phenomenon that the compressor speed does not change becomes significant. Further, since intermittent drive control cannot freely change the rotation speed of the electric motor, it is difficult to generate a targeted pulsation.

  In addition, since the phase of the intermittent drive is determined only in the crank angle range set in advance, there is a problem of reducing the volume efficiency of the engine without being able to control the optimum pressure pulsation when the engine speed changes. .

  In view of the above facts, an object of the present invention is to provide an engine supercharging device capable of improving intake charging efficiency with a simple configuration.

  An engine supercharging device according to the present invention includes an intake passage connected to an engine, an electric compressor provided in the intake passage and compressed by intake air flowing through the intake passage by being driven by a motor, and rotation of the engine A controller that periodically varies the rotational speed of the electric compressor so that an intake pulsation peak in the intake port is generated between the maximum lift of the intake valve and the valve closing, using the engine number and the crank angle of the engine as inputs And.

  In the engine supercharging device according to the present invention, the electric compressor is driven by a motor to compress the intake air flowing through the intake passage. At this time, the control unit receives the engine speed and the crank angle of the engine as inputs, and causes the intake pulsation peak in the intake port to occur between the maximum lift of the intake valve and the valve closing. The rotation speed is periodically changed.

  In this way, by changing the rotational speed of the electric compressor periodically so that the peak of the intake pulsation at the intake port occurs between the maximum lift of the intake valve and the closing of the intake valve, the intake air flow can be reduced with a simple configuration. Filling efficiency can be improved.

  The control unit according to the present invention can set the cycle of fluctuations in the rotational speed of the electric compressor to a period obtained by dividing the cycle of one cycle of the engine by the number of cylinders.

When the crank angle corresponding to the maximum lift of the intake valve is θ _A and the crank angle corresponding to the closing of the intake valve is θ _B , the control unit according to the present invention has θ _A + α (θ _B −θ _A ) to θ _A + β (θ _B −θ _A ) (where 0 <α <β <1), so that the intake pulsation peak occurs at the intake port. It is possible to control the phase of fluctuations in the number of rotations.

  The control unit according to the present invention, the phase of the fluctuation of the rotational speed of the electric compressor when the peak of the rotational speed of the electric compressor is generated between the maximum lift of the intake valve and the valve closing, Control can be made so that the pressure wave generated by the fluctuation in the rotational speed of the electric compressor is advanced by a delay until it reaches the intake port.

  The amount of delay until the pressure wave caused by the fluctuation in the rotational speed of the electric compressor reaches the intake port, the intake air pulsation in the intake port is measured at the intake port, and the fluctuation in the rotational speed of the electric compressor It can be obtained by calculating the phase shift.

  The delay until the pressure wave generated by the fluctuation of the rotational speed of the electric compressor reaches the intake port can be measured in advance according to the rotational speed and load of the engine.

  The control unit according to the present invention can periodically vary the rotational speed of the electric compressor by performing switching control between driving and regeneration of the motor.

  As described above, the engine supercharging device according to the present invention periodically varies the rotational speed of the electric compressor so that the peak of the intake pulsation at the intake port is generated between the maximum lift of the intake valve and the valve closing. By doing so, it has the outstanding effect that the charging efficiency of intake air can be improved with a simple configuration.

It is a figure showing a schematic structure of an engine system concerning a first embodiment of the present invention. (A) The graph which shows the change of the outlet pressure of an electric compressor, (B) The graph which shows the change of intake port pressure, and a valve lift. It is a graph which shows the relationship between the phase of the fluctuation | variation of the rotation speed of an electric compressor, and volumetric efficiency. (A) It is a graph for demonstrating the cycle of the fluctuation | variation of the rotation speed of an electric compressor, and (B) It is a graph for demonstrating a mode that the drive control and regeneration control are performed. (A) The figure which shows the operation map of the compressor in fixed rotation speed, (B) The figure which shows the operation map of the compressor in the case of controlling rotation speed. It is a graph which shows the relationship between an intake port pressure and a crank angle, and the relationship between a valve lift and a crank angle. (A) The graph which shows the relationship between intake port pressure and a crank angle, (B) The graph which shows the relationship between the pressure pulsation by the rotation speed fluctuation | variation of an electric compressor, and a crank angle. It is a graph which shows the relationship between a pressure pulsation and a crank angle, and the relationship between a valve lift and a crank angle. It is a graph which shows the relationship between the phase of the fluctuation | variation of the rotation speed of an electric compressor, and charging efficiency, and the charging efficiency in the case of fixed rotation speed. It is a graph which shows the relationship between the fluctuation | variation of the rotation speed of an electric compressor, and a crank angle, and the relationship between the pressure pulsation just after a compressor exit, and a crank angle. It is a graph which shows the relationship between the fluctuation | variation of the rotation speed of an electric compressor, and a crank angle, the relationship between the pressure pulsation immediately after a compressor exit, and a crank angle, and the relationship between the pressure pulsation in an intake port, and a crank angle. (A) The graph which shows the fluctuation | variation of the rotation speed of an electric compressor, and the pressure pulsation in an intake port, (B) The graph which shows the relationship between the fluctuation | variation of the rotation speed of an electric compressor, and a crank angle. It is a flowchart which shows the process routine by the controller of the engine supercharging apparatus which concerns on 1st embodiment of this invention. It is a flowchart which shows the process routine by the controller of the engine supercharging apparatus which concerns on 1st embodiment of this invention.

[First embodiment]
First, a first embodiment of the present invention will be described.

  FIG. 1 shows an overall configuration of an engine system S1 including an engine supercharging device 10 according to the first embodiment of the present invention.

  The engine system S1 shown in this figure is mounted on, for example, a vehicle such as a passenger car, and includes an engine supercharging device 10, an air cleaner 12, and an engine 14.

  The air cleaner 12 and the engine 14 have the same configuration as the conventional one. The engine 14 includes an intercooler 16, a throttle valve 17, an intake manifold 18, an engine body 20, and an exhaust manifold 22. An exhaust passage 24 is connected to the exhaust manifold 22.

  The exhaust passage 24 is connected to the aftertreatment device 50.

  The engine supercharging device 10 includes an intake passage 26, an electric compressor 32, a motor 34, an inverter 36, and a controller 40 as a control unit.

  The intake passage 26 is connected to the intercooler 16 of the engine 14.

  The electric compressor 32 includes a compressor unit that is driven by a motor 34, and the compressor unit includes an impeller 60.

  The impeller 60 is configured to compress intake air that is sucked from a suction port (not shown) and discharged from a discharge port (not shown) by being rotationally driven by the motor 34.

  The passage from the inlet to the outlet of the impeller 60 described above constitutes a part of the intake passage 26 shown in FIG.

  A sensor (not shown) provided in the engine body 20 detects the engine speed and the load along with the engine crank angle from the rotation of the crankshaft or camshaft of the engine, and responds to a signal corresponding to the engine speed and the engine load. A signal and a signal corresponding to the engine crank angle are output to the controller 40.

  Further, a flow meter (not shown) provided on the upstream side of the electric compressor 32 in the intake passage 26 is configured to output a signal corresponding to the intake flow rate to the controller 40.

  A pressure gauge 42 provided at the intake port of the engine 14 detects the intake pressure and outputs a signal corresponding to the intake pressure to the controller 40.

  The controller 40 is configured by an ECU, a logic circuit, and the like, and controls the motor 34 via the inverter 36 based on signals output from the sensors, flow meters, and pressure gauges 42 in the engine body 20. Has been.

  Next, the control principle by the controller 40 will be described.

  For turbochargers that use exhaust and superchargers that use engine power, the speed of the turbocharger is determined by the exhaust and engine speed, so the response speed is fast, especially within one cycle. Was difficult.

  However, since the electric compressor controls the rotation of the compressor impeller with a motor, the responsiveness is high and the rotational speed can be changed within one cycle.

  Unlike the conventional intake pulsation, the pressure wave at the intake port can be set to an arbitrary timing / waveform by controlling the electric compressor instead of the pressure wave depending on the intake pipe length and the engine speed (see FIG. 2).

  In FIG. 2, when the pressure wave at the intake port is controlled to (1) an optimal pressure pulsation waveform, (2) when controlled to a non-optimal pressure pulsation waveform, (3) the outlet pressure is controlled to be constant. The case is used as an example.

  (1) and (2) are controlled by shifting the timing of the pressure wave.

  By controlling at an optimal timing as in (1), inertial supercharging can be performed and volume efficiency is improved ((1) in FIG. (See (3)).

  On the other hand, when the timing is not optimized as in (2), the charging efficiency is reduced (see (2) in FIG. 3).

  Thus, the volumetric efficiency changes when the timing of the pressure wave at the outlet of the compressor impeller is changed. It turns out that volume efficiency improves by controlling to an optimal pressure wave.

  Therefore, in the present embodiment, the controller 40 controls the motor 34 that drives the electric compressor 32 by calculating an optimum pressure wave by calculating from time to time.

  At this time, control is performed to optimally change the rotational speed of the electric compressor 32 within one cycle in accordance with the rotational speed and load of the engine 14.

  In the present embodiment, the controller 40 receives information on the rotational speed, crank angle, and load of the engine 14 and determines the optimal rotational speed / timing of the electric compressor for the engine operating conditions.

  The rotational speed of the electric compressor is controlled to periodically change during one cycle of the engine 14. Specifically, during one cycle of the engine 14, there are as many cycles of fluctuations in the rotational speed of the electric compressor 32 as the number of cylinders. For example, in the case of a four-cylinder engine, there are only four cycles of fluctuations in the rotational speed of the electric compressor during one cycle of the engine (see FIG. 4A).

  In the example of FIG. 4A, the rotational speed is changed as a sine wave, but as shown in FIG. 4B, by controlling the inverter 36 and applying a drive / regenerative current to the motor 34, The waveform of the rotational speed of the electric compressor 32 can be accurately set to a target waveform.

  The amplitude of the rotational speed at this time is determined by the torque capacity (motor output limit) of the electric compressor and the operating line on the compressor map (see FIGS. 5A and 5B). That is, the motor amplitude is changed within a range where the motor output limit is not exceeded and the operating region of the compressor does not enter the surge region and the choke region.

  Further, by changing the rotational speed of the electric compressor, the operating range of the compressor changes at a constant rotational speed. Therefore, even if the average rotational speed or the output used by the motor is the same, the pressure wave output from the compressor is different. It is also possible to selectively use a range where the efficiency of the compressor is good by changing the rotation speed. However, it is necessary to control the amplitude of the rotation speed of the compressor so that the operating range of the compressor does not enter the surge region or the choke region.

  In addition, when the pressure wave of the intake port is compared with the case of a constant rotational speed, the pressure immediately before the valve lift closes increases when the rotational speed is optimally controlled, and the effect of inertia supercharging is obtained. It can be seen (see FIG. 6).

  Due to this effect, the volumetric efficiency of the engine is improved when the rotational speed is controlled.

  Since the above-described effect occurs even under conditions where the engine speed and load are different, the volume efficiency of the engine is improved by controlling the optimal speed.

  Next, the phase of the rotational speed of the electric compressor will be described.

  When a pressure wave having a high pressure immediately before the intake valve closes reaches the intake port, the charging efficiency is improved by inertia supercharging. That is, in order to improve the charging efficiency, it is necessary to control the phase of the pressure wave that reaches the intake port.

  The pressure fluctuation caused by the control for changing the rotation speed of the electric compressor is obtained by the difference between the pressure when the electric compressor is controlled at a constant rotation speed and the pressure at the time of control for changing the pressure (see FIG. 7). If this pressure wave reaches the phase determined next with respect to the closing timing of the valve, the charging efficiency is improved.

The crank angle at which the intake valve lift is maximum is θ _A , and the timing at which the intake valve closes is θ _B. The crank angle at which the pressure fluctuation obtained by the difference between the pressure at the intake port when the electric compressor is controlled at a constant rotational speed and the pressure at the intake port at the time of control for varying the rotational speed is θ _peak . . The rotational speed of the electric compressor is controlled so that this θ _peak falls between the crank angles θ _C and θ _D defined below (see FIG. 8).

θ _C = θ _A +0.2 (θ _B -θ _A )
θ _D = θ _A +0.85 (θ _B -θ _A )

If the rotation speed of the electric compressor can be controlled so that θ _peak is generated between the crank angles θ _C and θ _D , it is the same as when the rotation speed of the electric compressor is constant (see FIG. 9). The charging efficiency can be improved with the power consumption.

Further, as shown in FIG. 10, immediately after the compressor outlet, the phase of the rotational speed fluctuation of the electric compressor and the pressure wave generated by the rotational speed fluctuation control (at the time of control to change the pressure when the electric compressor is controlled at a constant rotational speed). The phase of the pressure difference is equal. That is, the peak of the pressure wave immediately after the compressor outlet is equal to the peak of the rotational speed of the electric compressor, and the peak crank angle is defined as θ _{peak_comp} .

Further, a phase delay occurs until the pressure wave generated by the change in the rotation speed of the electric compressor reaches the intake port (see FIG. 11). This phase _delay is defined as θ _delay . for that reason,
θ _C -θ _delay <θ _{peak_comp} <θ _D -θ _delay
Thus, the fluctuation of the rotation speed of the electric compressor is controlled.

In addition, the pressure gauge 42 provided at the intake port senses a pressure wave, the crank angle θ _{peak_comp at} which the rotational speed fluctuation of the electric compressor peaks, and the pressure when the electric compressor at the intake port is controlled at a constant rotational speed, The difference from the crank angle θ _{peak at} which the pressure fluctuation obtained by the pressure difference at the time of control to be varied becomes the maximum is the phase delay θ _delay . Considering the phase difference obtained by this,
θ _C -θ _delay <θ _{peak_comp} <θ _D -θ _delay
The rotational speed of the electric compressor is controlled so as to be (see FIG. 12).

  In accordance with the above principle, in the present embodiment, the controller 40 first measures and records in advance the pressure wave generated in the intake port when the rotational speed of the electric compressor 32 is made constant with the pressure gauge 42. .

  Further, the controller 40 calculates the average value and amplitude in the fluctuation of the rotational speed of the electric compressor 32 by using the rotational speed of the engine 14, the load, the crank angle of the engine 14, the intake flow rate, the required torque, and the specifications of the engine 14 as inputs. The cycle of the rotational speed of the electric compressor 32 is set to a period obtained by dividing the cycle of one cycle of the engine 14 by the number of cylinders, and the phase of the rotational speed fluctuation of the electric compressor 32 is set to an initial value. The rotational speed of 32 is periodically changed. At this time, the pressure wave generated in the intake port is measured by the pressure gauge 42, and compared with the pressure wave recorded in advance, the crank angle at which the pressure fluctuation obtained by the pressure wave difference is maximized is calculated. By calculating the difference between the crank angle at which the calculated pressure fluctuation becomes maximum and the crank angle at which the fluctuation of the rotation speed of the electric compressor 32 reaches a peak, the pressure wave caused by the fluctuation of the rotation speed of the electric compressor 32 is sucked. Calculate the delay until reaching the port.

Then, the controller 40 operates the electric compressor so that the fluctuation of the rotational speed of the electric compressor 32 peaks during the period from θ _A +0.2 (θ _B −θ _A ) to θ _A +0.85 (θ _B −θ _A ). After correcting the phase of fluctuation of the rotational speed of the compressor 32, the phase of fluctuation of the rotational speed of the electric compressor 32 is calculated until the pressure wave generated by the fluctuation of the rotational speed of the electric compressor 32 reaches the intake port. Further correction is made so as to advance by the delay amount, and the rotational speed of the electric compressor 32 is periodically changed so that the peak of the intake pulsation in the intake port is generated between the maximum lift of the intake valve and the valve closing.

  Next, the operation and effect will be described together with the operation of the engine supercharging device 10 according to the first embodiment of the present invention.

  First, in advance, the electric compressor 32 is operated at a constant rotational speed, and the pressure wave generated at the intake port when the rotational speed of the electric compressor 32 is made constant by the pressure gauge 42 is measured and recorded.

  FIG. 13 shows a flowchart representing the operation of the controller 40. The operation of the controller 40 shown in the flowchart of FIG. 13 is always performed during engine operation so as to follow the transient operation state of the engine.

  When the program process shown in the flowchart of FIG. 13 is started, the controller 40 first detects various sensors provided in the engine body 20 and the output signals of the flowmeters in step S100.

  Subsequently, in step S102, the controller 40 determines the rotation of the electric compressor 32 during a period obtained by dividing the cycle of one cycle of the engine 14 by the number of cylinders based on the number of rotations of the engine 14 and the engine specifications (number of cylinders). Calculated as the period of number fluctuation.

  In step S104, the controller 40 sets the phase of fluctuation in the rotational speed of the electric compressor 32 to an initial value based on the engine specifications (the crank angle corresponding to the open valve and the crank angle corresponding to the closed valve). To do.

  In step S106, the controller 40 receives the engine speed, the load, the crank angle of the engine 14, the intake flow rate, the required torque, and the engine specifications (displacement amount, intake pipe length) as inputs. In step S108, an average value of fluctuations in the rotational speed is calculated. Based on the specifications of the motor 34 of the electric compressor 32 (upper limit of rotational speed, upper limit of torque) and the compressor map (surge line, choke line, efficiency), The amplitude of fluctuation in the rotational speed of the electric compressor 32 corresponding to the usable range of the compressor 32 is calculated.

  In step S110, the controller 40 periodically sets the rotational speed of the electric compressor 32 using the cycle, phase, average value, and amplitude of the rotational speed fluctuation of the electric compressor 32 obtained in steps S102 to S108. Fluctuate.

  In step S112, the controller 40 measures the pressure wave generated in the intake port with the pressure gauge 42. In step S114, the controller 40 compares the pressure wave measured in step S112 with the pressure wave recorded in advance, and the crank whose pressure fluctuation obtained by the pressure wave difference is maximum is maximized. The angle is calculated, and the difference between the crank angle at which the calculated pressure fluctuation becomes maximum and the crank angle at which the fluctuation of the rotation speed of the electric compressor 32 reaches a peak is calculated, thereby causing the fluctuation of the rotation speed of the electric compressor 32. The delay until the pressure wave reaches the intake port is calculated.

In step S116, the controller 40 peaks the fluctuation of the rotational speed of the electric compressor 32 during the period from θ _A +0.2 (θ _B −θ _A ) to θ _A +0.85 (θ _B −θ _A ). Thus, after correcting the phase of fluctuation of the rotational speed of the electric compressor 32, the phase of fluctuation of the rotational speed of the electric compressor 32 is further corrected so as to be advanced by the delay calculated in step S114.

  In step S118, the controller 40 determines whether or not the pulsation control is more effective than the constant rotation control based on the limitation of the motor 34 or the like. When it is determined that the pulsation control is more effective, the process proceeds to step S120, and the cycle, phase, average value, and amplitude of fluctuations in the rotational speed of the electric compressor 32 obtained in steps S102 to S108 and S116 are performed. Is used to periodically vary the rotational speed of the electric compressor 32.

  On the other hand, when it is determined that the pulsation control is not effective, the controller 40 uses the average value of the rotation speed of the electric compressor 32 obtained in step S106 in step S122 to rotate the rotation speed of the electric compressor 32. Is controlled to be constant.

  As described above, according to the engine supercharging device 10 according to the first embodiment of the present invention, the electric intake pulsation peak in the intake port is electrically generated so as to occur between the maximum lift of the intake valve and the valve closing. By periodically changing the rotation speed of the compressor, the optimum intake pulsation occurs with respect to the intake valve timing, and the charging efficiency is improved by inertia supercharging. Therefore, the intake charging efficiency is improved with a simple configuration. Can do.

  Even in a conventional engine, pulsation occurs in the intake pressure due to the balance between the inertial force generated by the movement of fresh air, the suction input due to the lowering of the piston, and the length of the intake pipe. However, depending on the design specifications and operating conditions, the intake efficiency is lowered without the optimal pulsation timing. On the other hand, it is possible to artificially control pulsation by controlling a highly responsive electric compressor by the above-described method, and it is possible to generate intake pulsation that obtains optimum filling efficiency. Thus, the engine charging efficiency is improved, so that the output is improved. Moreover, since the electric power consumed by the electric compressor is reduced, the engine system has low fuel consumption.

  Even when the output of the electric compressor is large, the control is performed in consideration of the phase delay as described above.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In addition, about the part which becomes the same structure as 1st embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the engine system according to the second embodiment of the present invention, a case where a pressure gauge is not provided in the air supply port will be described as an example.

  That is, the engine system according to the second embodiment of the present invention is not provided with the pressure gauge 42 as compared with the engine system S1 according to the first embodiment of the present invention described above. The other configuration of the engine system is the same as that of the engine system S1 according to the first embodiment of the present invention described above.

  In the second embodiment, experimentally, a phase lag is measured in advance for each operating condition such as the engine speed and load, and a map storing the phase lag measured for each operating condition is prepared. deep.

  The controller 40 calculates a phase delay from a map prepared in advance based on operating conditions such as the rotation speed and load of the engine 14.

  Further, the controller 40 receives the engine speed, the load, the crank angle of the engine 14, the intake air flow rate, and the required torque, and calculates an average value and an amplitude in the fluctuation of the speed of the electric compressor 32. The period of fluctuation in the rotational speed is a period obtained by dividing the period of one cycle of the engine 14 by the number of cylinders.

Then, the controller 40 controls the electric compressor 32 so that the peak of pressure pulsation at the intake port comes during the period from θ _A +0.2 (θ _B −θ _A ) to θ _A +0.85 (θ _B −θ _A ). After calculating the phase of the fluctuation of the rotational speed of the electric compressor 32, the phase of the fluctuation of the rotational speed of the electric compressor 32 is corrected so as to be advanced by the calculated phase delay, and the rotational speed of the electric compressor 32 is periodically changed. .

Thus, the controller 40, depending on the operating conditions _{θ C - θ delay <θ peak_comp} <θ D - controlling the rotational speed of the electric compressor 32 such that theta _delay.

  FIG. 14 shows a flowchart representing the operation of the controller 40. The operation of the controller 40 shown in the flowchart of FIG. 14 is always performed during engine operation so as to follow the transient operation state of the engine. In addition, about the process similar to 1st embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  When the controller 40 starts the program processing shown in the flowchart of FIG. 14, first, in step S100, the controller 40 detects output signals from various sensors provided in the engine body 20 and the flow meter.

  Subsequently, in step S102, the controller 40 determines the rotation of the electric compressor 32 during a period obtained by dividing the cycle of one cycle of the engine 14 by the number of cylinders based on the number of rotations of the engine 14 and the engine specifications (number of cylinders). Calculated as the period of number fluctuation.

  In step S200, the controller 40 calculates a phase lag from a map prepared in advance based on the rotational speed and load of the engine 14 and the engine specifications.

In step S202, the controller 40 determines from θ _A +0.2 (θ _B −θ _A ) to θ _A +0.85 (θ _B ) based on the phase delay calculated in step S200 and the engine specifications (valve timing). -θ _A ) After calculating the phase of the fluctuation of the rotational speed of the electric compressor 32 so that the peak of the fluctuation of the rotational speed of the electric compressor 32 is reached, the phase of the fluctuation of the rotational speed of the electric compressor 32 is calculated. Is corrected so as to be advanced by the calculated phase delay, thereby calculating the phase of fluctuation of the rotational speed of the electric compressor 32.

  In step S106, the controller 40 receives the engine speed, the load, the crank angle of the engine 14, the intake flow rate, the required torque, and the engine specifications (displacement amount, intake pipe length) as inputs. In step S108, an average value of fluctuations in the rotational speed is calculated. Based on the specifications of the motor 34 of the electric compressor 32 (upper limit of rotational speed, upper limit of torque) and the compressor map (surge line, choke line, efficiency), The amplitude of fluctuation in the rotational speed of the electric compressor 32 corresponding to the usable range of the compressor 32 is calculated.

  In step S118, the controller 40 determines whether or not the pulsation control is more effective than the constant rotation control based on the limitation of the motor 34 or the like. When it is determined that the pulsation control is more effective, the process proceeds to step S120, and the cycle, phase, and average value of the fluctuations in the rotational speed of the electric compressor 32 obtained in steps S102, S202, S106, and S108. The rotation speed of the electric compressor 32 is periodically changed using the amplitude.

  On the other hand, when it is determined that the pulsation control is not effective, the controller 40 uses the average value of the rotation speed of the electric compressor 32 obtained in step S106 in step S122 to rotate the rotation speed of the electric compressor 32. Is controlled to be constant.

  Thus, even with the engine supercharging device according to the second embodiment of the present invention, the rotational speed of the electric compressor is such that the peak of the intake pulsation in the intake port is generated between the maximum lift of the intake valve and the valve closing. By periodically varying the intake pulsation, the optimum intake pulsation occurs with respect to the intake valve timing, and the charging efficiency is improved by inertia supercharging. Therefore, the intake charging efficiency can be improved with a simple configuration.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited above, Of course, it can change and implement variously within the range which does not deviate from the main point. .

DESCRIPTION OF SYMBOLS 10 Engine supercharger 12 Air cleaner 14 Engine 16 Intercooler 17 Throttle valve 18 Intake manifold 20 Engine main body 22 Exhaust manifold 24 Exhaust passage 26 Intake passage 32 Electric compressor 34 Motor 36 Inverter 40 Controller 42 Pressure gauge 50 Aftertreatment device 60 Impeller S1 Engine system

Claims (7)

An intake passage connected to the engine;
An electric compressor that is provided in the intake passage and that is driven by a motor to compress intake air flowing through the intake passage;
Using the engine speed and the crank angle of the engine as inputs, the rotational speed of the electric compressor is periodically changed so that a peak of intake pulsation at the intake port occurs between the maximum lift of the intake valve and the valve closing. A variable control unit;
Including engine supercharger.   2. The engine supercharging device according to claim 1, wherein the control unit sets a cycle of fluctuation in the rotation speed of the electric compressor as a period obtained by dividing a cycle of one cycle of the engine by the number of cylinders. When the crank angle corresponding to the maximum lift of the intake valve is θ _A and the crank angle corresponding to the closing of the intake valve is θ _B , the control unit calculates from θ _A + α (θ _B −θ _A ). The rotational speed of the electric compressor is such that the peak of intake pulsation at the intake port occurs during the period up to θ _A + β (θ _B −θ _A ) (where 0 <α <β <1). The engine supercharging device according to claim 1, wherein the phase of fluctuation of the engine is controlled.   The controller is configured to determine a phase of fluctuation in the rotational speed of the electric compressor when a peak of the rotational speed of the electric compressor is generated between a maximum lift and a valve closing of the intake valve. The engine supercharging device according to any one of claims 1 to 3, wherein control is performed so that a pressure wave generated by fluctuations in the rotational speed of the engine is advanced by a delay until the pressure wave reaches the intake port. The amount of delay until the pressure wave caused by fluctuations in the rotational speed of the electric compressor reaches the intake port,
The engine supercharging device according to claim 4, which is obtained by measuring an intake air pulsation at the intake port at the intake port and calculating a phase shift from a fluctuation in the rotational speed of the electric compressor.   The engine supercharging device according to claim 4, wherein a delay amount until a pressure wave caused by fluctuations in the rotational speed of the electric compressor reaches the intake port is measured in advance according to the rotational speed and load of the engine. .   The engine supercharging device according to any one of claims 1 to 6, wherein the control unit periodically changes the rotational speed of the electric compressor by performing switching control between driving and regeneration of the motor.